TY - JOUR A1 - Sentance, Sue A1 - Hodges, Steve T1 - .NET Gadgeteer Workshop JF - Commentarii informaticae didacticae : (CID) Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64654 SN - 1868-0844 SN - 2191-1940 IS - 6 SP - 159 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - CHAP A1 - Reyes-Iturbide, J. A1 - Velázquez, P. A1 - Rosado, M. T1 - 3D numerical model for an asymmetrical superbubble N2 - Massive stars usually form groups such as OB associations. Their fast stellar winds sweep up collectively the surrounding insterstellar medium (ISM) to generate superbubbles. Observations suggest that superbubble evolution on the surrounding ISM can be very irregular. Numerical simulations considering these conditions could help to understand the evolution of these superbubbles and to clarify the dynamics of these objects as well as the difference between observed X-ray luminosities and the predicted ones by the standard model (Weaver et al. 1977). Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17724 ER - TY - THES A1 - Swierczynski, Tina T1 - A 7000 yr runoff chronology from varved sediments of Lake Mondsee (Upper Austria) T1 - Eine 7000-jährige Abflusschronologie anhand von warvierten Sedimenten des Mondsees (Oberösterreich) N2 - The potential increase in frequency and magnitude of extreme floods is currently discussed in terms of global warming and the intensification of the hydrological cycle. The profound knowledge of past natural variability of floods is of utmost importance in order to assess flood risk for the future. Since instrumental flood series cover only the last ~150 years, other approaches to reconstruct historical and pre-historical flood events are needed. Annually laminated (varved) lake sediments are meaningful natural geoarchives because they provide continuous records of environmental changes > 10000 years down to a seasonal resolution. Since lake basins additionally act as natural sediment traps, the riverine sediment supply, which is preserved as detrital event layers in the lake sediments, can be used as a proxy for extreme discharge events. Within my thesis I examined a ~ 8.50 m long sedimentary record from the pre-Alpine Lake Mondsee (Northeast European Alps), which covered the last 7000 years. This sediment record consists of calcite varves and intercalated detrital layers, which range in thickness from 0.05 to 32 mm. Detrital layer deposition was analysed by a combined method of microfacies analysis via thin sections, Scanning Electron Microscopy (SEM), μX-ray fluorescence (μXRF) scanning and magnetic susceptibility. This approach allows characterizing individual detrital event layers and assigning a corresponding input mechanism and catchment. Based on varve counting and controlled by 14C age dates, the main goals of this thesis are (i) to identify seasonal runoff processes, which lead to significant sediment supply from the catchment into the lake basin and (ii) to investigate flood frequency under changing climate boundary conditions. This thesis follows a line of different time slices, presenting an integrative approach linking instrumental and historical flood data from Lake Mondsee in order to evaluate the flood record inferred from Lake Mondsee sediments. The investigation of eleven short cores covering the last 100 years reveals the abundance of 12 detrital layers. Therein, two types of detrital layers are distinguished by grain size, geochemical composition and distribution pattern within the lake basin. Detrital layers, which are enriched in siliciclastic and dolomitic material, reveal sediment supply from the Flysch sediments and Northern Calcareous Alps into the lake basin. These layers are thicker in the northern lake basin (0.1-3.9 mm) and thinner in the southern lake basin (0.05-1.6 mm). Detrital layers, which are enriched in dolomitic components forming graded detrital layers (turbidites), indicate the provenance from the Northern Calcareous Alps. These layers are generally thicker (0.65-32 mm) and are solely recorded within the southern lake basin. In comparison with instrumental data, thicker graded layers result from local debris flow events in summer, whereas thin layers are deposited during regional flood events in spring/summer. Extreme summer floods as reported from flood layer deposition are principally caused by cyclonic activity from the Mediterranean Sea, e.g. July 1954, July 1997 and August 2002. During the last two millennia, Lake Mondsee sediments reveal two significant flood intervals with decadal-scale flood episodes, during the Dark Ages Cold Period (DACP) and the transition from the Medieval Climate Anomaly (MCA) into the Little Ice Age (LIA) suggesting a linkage of transition to climate cooling and summer flood recurrences in the Northeastern Alps. In contrast, intermediate or decreased flood episodes appeared during the MWP and the LIA. This indicates a non-straightforward relationship between temperature and flood recurrence, suggesting higher cyclonic activity during climate transition in the Northeast Alps. The 7000-year flood chronology reveals 47 debris flows and 269 floods, with increased flood activity shifting around 3500 and 1500 varve yr BP (varve yr BP = varve years before present, before present = AD 1950). This significant increase in flood activity shows a coincidence with millennial-scale climate cooling that is reported from main Alpine glacier advances and lower tree lines in the European Alps since about 3300 cal. yr BP (calibrated years before present). Despite relatively low flood occurrence prior to 1500 varve yr BP, floods at Lake Mondsee could have also influenced human life in early Neolithic lake dwellings (5750-4750 cal. yr BP). While the first lake dwellings were constructed on wetlands, the later lake dwellings were built on piles in the water suggesting an early flood risk adaptation of humans and/or a general change of the Late Neolithic Culture of lake-dwellers because of socio-economic reasons. However, a direct relationship between the final abandonment of the lake dwellings and higher flood frequencies is not evidenced. N2 - Ein verstärktes Auftreten von Hochwassern, sowohl in ihrer Häufigkeit als auch in ihrer Frequenz, wird im Zuge der Klimaerwärmung und einer möglichen Intensivierung des hydrologischen Kreislaufs diskutiert. Die Kenntnis über die natürliche Variabilität von Hochwasserereignissen ist dabei eine grundlegende Voraussetzung, um die Hochwassergefahr für die Zukunft abschätzen zu können. Da instrumentelle Hochwasserzeitreihen meist nur die letzten 150 Jahre abbilden sind andere Methoden erforderlich, um das Auftreten von historischen und prä-historischen Hochwassern festzustellen. Jährlich laminierte (warvierte) Seesedimente sind bedeutende natürliche Archive, denn sie liefern kontinuierliche Zeitreihen > 10000 Jahre mit einer bis zur saisonalen Auflösung. Seebecken stellen natürliche Sedimentfallen dar, wobei eingetragenes Flusssediment in den Seesedimenten als eine distinkte detritische Lage aufgezeichnet wird, und daher zur Rekonstruktion von extremen Abflussereignissen genutzt werden. Im Rahmen meiner Doktorarbeit habe ich einen 8.50 m langen Sedimentkern aus dem Mondsee (Nordostalpen) untersucht, welcher die letzten 7000 Jahre abdeckt. Dieser Sedimentkern besteht aus Kalzitwarven und eingeschalteten detritischen Lagen mit einer Mächtigkeit von 0.05-32 mm. Detritische Lagen wurden mit Hilfe einer kombinierten Methode untersucht: Mikrofaziesanalyse, Rasterelektronenmikroskopie, Röntgenfluoreszenzanalyse (µXRF) und magnetische Suszeptibilität. Dieser Ansatz ermöglicht die Charakterisierung der einzelnen detritischen Lagen bezüglich der Eintragsprozesse und die Lokalisierung des Einzugsgebietes. Auf Grundlage der Warvenzählung und 14C Datierungen sind die wichtigsten Ziele dieser Arbeit: (i) die Identifizierung der Eintragsprozesse, welche zu einem Sedimenteintrag vom Einzugsgebiet bis in den See führen und (ii) die Rekonstruktion der Hochwasserfrequenz unter veränderten Klimabedingungen. Diese Arbeit zeigt eine Untersuchung auf verschiedenen Zeitscheiben, wobei instrumentelle und historische Daten genutzt werden, um die Aufzeichnung von pre-historischen Hochwasser in den Mondseesedimenten besser zu verstehen. Innerhalb der letzten 100 Jahre wurden zwölf Abflussereignisse aufgezeichnet. Zwei Typen von detritschen Lagen können anhand von Korngröße, geochemischer Zusammensetzung und des Verteilungsmusters unterschieden werden. Detritische Lagen, welche aus siliziklastischen und dolomitischen Material bestehen, zeigen eine Sedimentherkunft vom Teileinzugsgebiet des Flysch (nördliches Einzugsgebiet) und der Nördlichen Kalkalpen (südliches Teileinzugsgebiet) auf. Diese Lagen sind im Nördlichen Becken mächtiger (0.1-3.9 mm) als im südlichen Seebecken (0.05-1.6 mm). Detritische Lagen, welche nur aus dolomitischem Material bestehen und Turbititlagen aufzeigen (0.65-32 mm), weisen auf eine Herkunft aus den Nördlichen Kalkalpen hin. Im Vergleich mit instrumentellen Zeitreihen, stammen die mächtigeren Lagen von lokalen Murereignissen im Sommer und feinere Eintragslagen von regionalen Frühjahrs- und Sommerhochwassern. Extreme Sommerhochwasser am Mondsee werden hauptsächlich durch Zyklonen vom Mittelmeer ausgelöst, z.B. Juli 1954, Juli 1997 und August 2002. Die Untersuchung des langen Sedimentkerns vom Mondsee zeigt während der letzten 2000 Jahre signifikante Hochwasserintervalle mit dekadischen Hochwasserepisoden während der Völkerwanderungszeit und im Übergang vom Mittelalter in die Kleine Eiszeit. Dies weist auf eine Verknüpfung von Abkühlungsphasen und Sommerhochwassern im Nordostalpenraum hin. Während der Mittelalterlichen Wärmephase und in der Kleinen Eiszeit kam es jedoch zu einer geringeren Hochwasseraktivität. Dies zeigt einen komplexen Zusammenhang von Temperaturentwicklung und Hochwasseraktivität in den Nordostalpen, mit einer erhöhten Zyklonenaktivät in den Übergängen von wärmeren zu kälteren Phasen. Während der letzten 7000 Jahre wurden 47 Muren und 269 Hochwasser aufgezeichnet, wobei es eine signifikante Änderung mit erhöhter Häufigkeit um 3500 und 1500 Warvenjahre v. h. gab (v.h. = vor heute = AD 1950). Diese signifikante Änderung stimmt mit einem langfristigem Abkühlungstrend überein, welcher durch alpine Gletschervorstöße und das Absinken von Baumgrenzen seit etwa 3300 Warvenjahre v.h. berichtet wird. Trotz relativ geringer Hochwasseraktivität um 1500 Warvenjahre v.h., könnte das Auftreten von Hochwasser auch das Leben Menschen in Neolithischen Pfahlbausiedlungen (5750-4750 cal. yr BP) beeinflusst haben. Während die ersten Pfahlbauten noch als Feuchtbodensiedlungen am Land entstanden, wurden spätere Siedlungen eventuell als Anpassung an stark schwankenden Seewasserspiegeln auf Pfählen im Wasser gebaut und/oder zeigen eine allgemeine Veränderung der Siedlungsaktivitäten der Neolithischen Pfahlbaukultur an, aufgrund sozio-ökonomischer Veränderungen. Ein direkter Zusammenhang zwischen dem Verlassen der Pfahlbausiedlungen und einer erhöhten Hochwasseraktivität konnte jedoch nicht festgestellt werden. KW - Mondsee KW - Paläohochwasser KW - Seesedimente KW - Warven KW - Klimarekonstruktion KW - Mondsee KW - Paleofloods KW - Lake sediments KW - Warves KW - Climate reconstruction Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-66702 ER - TY - JOUR A1 - Dagiene, Valentina A1 - Jevsikova, Tatjana A1 - Schule, Carsten A1 - Sentance, Sue A1 - Thota, Neena T1 - A comparison of current trends within computer science teaching in school in Germany and the UK JF - Commentarii informaticae didacticae : (CID) N2 - In the last two years, CS as a school subject has gained a lot of attention worldwide, although different countries have differing approaches to and experiences of introducing CS in schools. This paper reports on a study comparing current trends in CS at school, with a major focus on two countries, Germany and UK. A survey was carried out of a number of teaching professionals and experts from the UK and Germany with regard to the content and delivery of CS in school. An analysis of the quantitative data reveals a difference in foci in the two countries; putting this into the context of curricular developments we are able to offer interpretations of these trends and suggest ways in which curricula in CS at school should be moving forward. KW - CS Ed Research KW - ICT KW - CS at school KW - CS curriculum KW - topics KW - international comparison KW - international study Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64504 SN - 1868-0844 SN - 2191-1940 IS - 6 SP - 63 EP - 75 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - RPRT A1 - Baganz, Melissa A1 - de Teresa, Aurelia Gómez A1 - Lingg, Rosana T. A1 - Montijo, Yuriditzi Pascacio T1 - A critical assessment on National Action Plans BT - Challenges and benefits for the promotion and protection of Human Rights T2 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere T2 - State, Law, and Politics - Research and Discussion Papers N2 - National Action Plans (NAPs) have been increas-ingly adopted world-wide after the Vienna Dec-laration in 1993, where it was urged to consider the improvement and promotion of Human Rights. In this paper, we discuss their usefulness and success by analysing the challenges present-ed during NAP processes as well as the benefits this set of actions entails: The challenges for their implementation outweigh its actual benefits. Nevertheless, NAPs have great potential. Based on new research, we elaborate a set of recom-mendations for improving the design and imple-mentation of national action planning. In order to effectively bring NAP into practice, we consider it crucial to plan and analyse every state local circumstances in detail. The latter is important, since the implementation of a concrete set of actions is intended to directly transform and improve the local living conditions of the people. In a long-term perspective, we defend the benefit of NAP’s implementation for complying obliga-tions set up by HR treaties. N2 - Nationale Aktionspläne (NAP) werden seit der Wiener Erklärung von 1993, in der die Verbesse-rung und Förderung der Menschenrechte gefor-dert wird, weltweit zunehmend angenommen. In diesem Papier diskutieren wir ihren Nutzen und Erfolg, indem wir die Herausforderungen, die sich während der NAP-Prozesse ergeben, sowie die Vorteile, die dieses Maßnahmenpaket mit sich bringt, analysieren: Die Herausforderungen bei ihrer Umsetzung überwiegen die tatsächlichen Vorteile. Dennoch haben NAPs ein großes Poten-zial. Beruhend auf neueren Forschungen erarbei-ten wir eine Reihe von Empfehlungen zur Ver-besserung der Gestaltung und Umsetzung der nationalen Aktionsplanung. Um einen NAP effek-tiv in die Praxis umzusetzen, halten wir es für entscheidend, die lokalen Gegebenheiten jedes Staates im Detail zu planen und zu analysieren. Letzteres ist wichtig, da die Umsetzung eines konkreten Maßnahmenpakets die Lebensbedin-gungen der Menschen vor Ort direkt verändern und verbessern soll. Langfristig gesehen vertei-digen wir den Nutzen der Umsetzung des NAP für die Einhaltung der in den Menschenrechts-verträgen festgelegten Verpflichtungen. T3 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere = State, Law, and Politics - Research and Discussion Papers - 13 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-576797 SN - 2509-6974 IS - 13 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - RPRT A1 - Hajos, Yael T1 - A Critical Overview of the Public Health Emergency of International Concern Mechanism BT - The Case of Covid-19 T2 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere T2 - State, Law, and Politics — Research and Discussion Papers N2 - The last years have been affected by Covid-19 and the international emergency mecha-nism to deal with health-related threats. The effects of this period manifested differ-ently worldwide, depending on matters such as international relations, national policies, power dynamics etc. Additionally, the impact of this time will likely have long-term effects which are yet to be known. This paper gives a critical overview of the Public Health Emergency of International Concern (PHEIC) mechanism in the context of Covid-19. It does so by explaining the legal framework for states of emergency, specifically in the context of a PHEIC, while considering its restrictions and limitations on human rights. It further outlines issues in the manifestation of global protections and limitations on human rights during Covid-19. Lastly, considering the likelihood of future PHEICs and the known systemic obstructions, this paper offers ways to im-prove this mechanism from a holistic, non-zero-sum perspective. N2 - Die letzten Jahre waren geprägt von Covid-19 und dem internationalen Notfallmecha-nismus zur Bewältigung gesundheitsbe-zogener Bedrohungen. Die Auswirkungen dieser Zeit zeigten sich weltweit unter-schiedlich, abhängig von den internatio-nalen Beziehungen, der nationalen Politik, der Machtdynamik usw. Außerdem werden die Auswirkungen dieser Zeit wahrschein-lich langfristige, heute noch unbekannte Folgen haben. Diese Studie gibt einen kriti-schen Überblick über den Mechanismus für internationale gesundheitliche Notfälle (Public Health Emergency of International Concern – PHEIC) im Kontext von Covid-19. Zu diesem Zweck wird der rechtliche Rahmen für Notfälle, insbesondere im Zusammenhang mit PHEIC, erläutert, und es werden die damit verbundenen Ein-schränkungen und Begrenzungen der Menschenrechte betrachtet. In Anbetracht der Wahrscheinlichkeit künftiger PHEICs und der bekannten systemischen Hin-dernisse bietet dieses Papier schließlich Möglichkeiten zur Verbesserung dieses Mechanismus aus einer ganzheitlichen Per-spektive. T3 - Staat, Recht und Politik – Forschungs- und Diskussionspapiere = State, Law, and Politics - Research and Discussion Papers - 15 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-585238 SN - 2509-6974 IS - 15 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - GEN A1 - Elsenbeer, Helmut A1 - Cassel, Keith A1 - Tinner, W. T1 - A daily rainfall erosivity model for Western Amazonia N2 - Rainfall erosivities as defined by the R factor from the universal soil loss equation were determined for all events during a two-year period at the station La Cuenca in western Amazonia. Three methods based on a power relationship between rainfall amount and erosivity were then applied to estimate event and daily rainfall erosivities from the respective rainfall amounts. A test of the resulting regression equations against an independent data set proved all three methods equally adequate in predicting rainfall erosivity from daily rainfall amount. We recommend the Richardson model for testing in the Amazon Basin, and its use with the coefficient from La Cuenca in western Amazonia. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 050 KW - MESOSCALE CONVECTIVE COMPLEXES KW - KINETIC-ENERGY KW - UNITED-STATES KW - EROSION Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16962 ER - TY - THES A1 - Tattarini, Giulia T1 - A job is good, but is a good job healthier? BT - Longitudinal analyses on the health consequences of unemployment and precarious employment in Europe N2 - What are the consequences of unemployment and precarious employment for individuals' health in Europe? What are the moderating factors that may offset (or increase) the health consequences of labor-market risks? How do the effects of these risks vary across different contexts, which differ in their institutional and cultural settings? Does gender, regarded as a social structure, play a role, and how? To answer these questions is the aim of my cumulative thesis. This study aims to advance our knowledge about the health consequences that unemployment and precariousness cause over the life course. In particular, I investigate how several moderating factors, such as gender, the family, and the broader cultural and institutional context, may offset or increase the impact of employment instability and insecurity on individual health. In my first paper, 'The buffering role of the family in the relationship between job loss and self-perceived health: Longitudinal results from Europe, 2004-2011', I and my co-authors measure the causal effect of job loss on health and the role of the family and welfare states (regimes) as moderating factors. Using EU-SILC longitudinal data (2004-2011), we estimate the probability of experiencing 'bad health' following a transition to unemployment by applying linear probability models and undertake separate analyses for men and women. Firstly, we measure whether changes in the independent variable 'job loss' lead to changes in the dependent variable 'self-rated health' for men and women separately. Then, by adding into the model different interaction terms, we measure the moderating effect of the family, both in terms of emotional and economic support, and how much it varies across different welfare regimes. As an identification strategy, we first implement static fixed-effect panel models, which control for time-varying observables and indirect health selection—i.e., constant unobserved heterogeneity. Secondly, to control for reverse causality and path dependency, we implement dynamic fixed-effect panel models, adding a lagged dependent variable to the model. We explore the role of the family by focusing on close ties within households: we consider the presence of a stable partner and his/her working status as a source of social and economic support. According to previous literature, having a partner should reduce the stress from adverse events, thanks to the symbolic and emotional dimensions that such a relationship entails, regardless of any economic benefits. Our results, however, suggest that benefits linked to the presence of a (female) partner also come from the financial stability that (s)he can provide in terms of a second income. Furthermore, we find partners' employment to be at least as important as the mere presence of the partner in reducing the negative effect of job loss on the individual's health by maintaining the household's standard of living and decreasing economic strain on the family. Our results are in line with previous research, which has highlighted that some people cope better than others with adverse life circumstances, and the support provided by the family is a crucial resource in that regard. We also reported an important interaction between the family and the welfare state in moderating the health consequences of unemployment, showing how the compensation effect of the family varies across welfare regimes. The family plays a decisive role in cushioning the adverse consequences of labor market risks in Southern and Eastern welfare states, characterized by less developed social protection systems and –especially the Southern – high level of familialism. The first paper also found important gender differences concerning job loss, family and welfare effects. Of particular interest is the evidence suggesting that health selection works differently for men and women, playing a more prominent role for women than for men in explaining the relationship between job loss and self-perceived health. The second paper, 'Gender roles and selection mechanisms across contexts: A comparative analysis of the relationship between unemployment, self-perceived health, and gender.' investigates more in-depth the gender differential in health driven by unemployment. Being a highly contested issue in literature, we aim to study whether men are more penalized than women or the other way around and the mechanisms that may explain the gender difference. To do that, we rely on two theoretical arguments: the availability of alternative roles and social selection. The first argument builds on the idea that men and women may compensate for the detrimental health consequences of unemployment through the commitment to 'alternative roles,' which can provide for the resources needed to fulfill people's socially constructed needs. Notably, the availability of alternative options depends on the different positions that men and women have in society. Further, we merge the availability of the 'alternative roles' argument with the health selection argument. We assume that health selection could be contingent on people's social position as defined by gender and, thus, explain the gender differential in the relationship between unemployment and health. Ill people might be less reluctant to fall or remain (i.e., self-select) in unemployment if they have alternative roles. In Western societies, women generally have more alternative roles than men and thus more discretion in their labor market attachment. Therefore, health selection should be stronger for them, explaining why unemployment is less menace for women than for their male counterparts. Finally, relying on the idea of different gender regimes, we extended these arguments to comparison across contexts. For example, in contexts where being a caregiver is assumed to be women's traditional and primary roles and the primary breadwinner role is reserved to men, unemployment is less stigmatized, and taking up alternative roles is more socially accepted for women than for men (Hp.1). Accordingly, social (self)selection should be stronger for women than for men in traditional contexts, where, in the case of ill-health, the separation from work is eased by the availability of alternative roles (Hp.2). By focusing on contexts that are representative of different gender regimes, we implement a multiple-step comparative approach. Firstly, by using EU-SILC longitudinal data (2004-2015), our analysis tests gender roles and selection mechanisms for Sweden and Italy, representing radically different gender regimes, thus providing institutional and cultural variation. Then, we limit institutional heterogeneity by focusing on Germany and comparing East- and West-Germany and older and younger cohorts—for West-Germany (SOEP data 1995-2017). Next, to assess the differential impact of unemployment for men and women, we compared (unemployed and employed) men with (unemployed and employed) women. To do so, we calculate predicted probabilities and average marginal effect from two distinct random-effects probit models. Our first step is estimating random-effects models that assess the association between unemployment and self-perceived health, controlling for observable characteristics. In the second step, our fully adjusted model controls for both direct and indirect selection. We do this using dynamic correlated random-effects (CRE) models. Further, based on the fully adjusted model, we test our hypotheses on alternative roles (Hp.1) by comparing several contexts – models are estimated separately for each context. For this hypothesis, we pool men and women and include an interaction term between unemployment and gender, which has the advantage to allow for directly testing whether gender differences in the effect of unemployment exist and are statistically significant. Finally, we test the role of selection mechanisms (Hp.2), using the KHB method to compare coefficients across nested nonlinear models. Specifically, we test the role of selection for the relationship between unemployment and health by comparing the partially-adjusted and fully-adjusted models. To allow selection mechanisms to operate differently between genders, we estimate separate models for men and women. We found support to our first hypotheses—the context where people are embedded structures the relationship between unemployment, health, and gender. We found no gendered effect of unemployment on health in the egalitarian context of Sweden. Conversely, in the traditional context of Italy, we observed substantive and statistically significant gender differences in the effect of unemployment on bad health, with women suffering less than men. We found the same pattern for comparing East and West Germany and younger and older cohorts in West Germany. On the contrary, our results did not support our theoretical argument on social selection. We found that in Sweden, women are more selected out of employment than men. In contrast, in Italy, health selection does not seem to be the primary mechanism behind the gender differential—Italian men and women seem to be selected out of employment to the same extent. Namely, we do not find any evidence that health selection is stronger for women in more traditional countries (Hp2), despite the fact that the institutional and the cultural context would offer them a more comprehensive range of 'alternative roles' relative to men. Moreover, our second hypothesis is also rejected in the second and third comparisons, where the cross-country heterogeneity is reduced to maximize cultural differences within the same institutional context. Further research that addresses selection into inactivity is needed to evaluate the interplay between selection and social roles across gender regimes. While the health consequences of unemployment have been on the research agenda for a pretty long time, the interest in precarious employment—defined as the linking of the vulnerable worker to work that is characterized by uncertainty and insecurity concerning pay, the stability of the work arrangement, limited access to social benefits, and statutory protections—has emerged only later. Since the 80s, scholars from different disciplines have raised concerns about the social consequences of de-standardization of employment relationships. However, while work has become undoubtedly more precarious, very little is known about its causal effect on individual health and the role of gender as a moderator. These questions are at the core of my third paper : 'Bad job, bad health? A longitudinal analysis of the interaction between precariousness, gender and self-perceived health in Germany'. Herein, I investigate the multidimensional nature of precarious employment and its causal effect on health, particularly focusing on gender differences. With this paper, I aim at overcoming three major shortcomings of earlier studies: The first one regards the cross-sectional nature of data that prevents the authors from ruling out unobserved heterogeneity as a mechanism for the association between precarious employment and health. Indeed, several unmeasured individual characteristics—such as cognitive abilities—may confound the relationship between precarious work and health, leading to biased results. Secondly, only a few studies have directly addressed the role of gender in shaping the relationship. Moreover, available results on the gender differential are mixed and inconsistent: some found precarious employment being more detrimental for women's health, while others found no gender differences or stronger negative association for men. Finally, previous attempts to an empirical translation of the employment precariousness (EP) concept have not always been coherent with their theoretical framework. EP is usually assumed to be a multidimensional and continuous phenomenon; it is characterized by different dimensions of insecurity that may overlap in the same job and lead to different "degrees of precariousness." However, researchers have predominantly focused on one-dimensional indicators—e.g., temporary employment, subjective job insecurity—to measure EP and study the association with health. Besides the fact that this approach partially grasps the phenomenon's complexity, the major problem is the inconsistency of evidence that it has produced. Indeed, this line of inquiry generally reveals an ambiguous picture, with some studies finding substantial adverse effects of temporary over permanent employment, while others report only minor differences. To measure the (causal) effect of precarious work on self-rated health and its variation by gender, I focus on Germany and use four waves from SOEP data (2003, 2007, 2011, and 2015). Germany is a suitable context for my study. Indeed, since the 1980s, the labor market and welfare system have been restructured in many ways to increase the German economy's competitiveness in the global market. As a result, the (standard) employment relationship has been de-standardized: non-standard and atypical employment arrangements—i.e., part-time work, fixed-term contracts, mini-jobs, and work agencies—have increased over time while wages have lowered, even among workers with standard work. In addition, the power of unions has also fallen over the last three decades, leaving a large share of workers without collective protection. Because of this process of de-standardization, the link between wage employment and strong social rights has eroded, making workers more powerless and more vulnerable to labor market risks than in the past. EP refers to this uneven distribution of power in the employment relationship, which can be detrimental to workers' health. Indeed, by affecting individuals' access to power and other resources, EP puts precarious workers at risk of experiencing health shocks and influences their ability to gain and accumulate health advantages (Hp.1). Further, the focus on Germany allows me to investigate my second research question on the gender differential. Germany is usually regarded as a traditionalist gender regime: a context characterized by a configuration of roles. Here, being a caregiver is assumed to be women's primary role, whereas the primary breadwinner role is reserved for men. Although many signs of progress have been made over the last decades towards a greater equalization of opportunities and more egalitarianism, the breadwinner model has barely changed towards a modified version. Thus, women usually take on the double role of workers (the so-called secondary earner) and caregivers, and men still devote most of their time to paid work activities. Moreover, the overall upward trend towards more egalitarian gender ideologies has leveled off over the last decades, moving notably towards more traditional gender ideologies. In this setting, two alternative hypotheses are possible. Firstly, I assume that the negative relationship between EP and health is stronger for women than for men. This is because women are systematically more disadvantaged than men in the public and private spheres of life, having less access to formal and informal sources of power. These gender-related power asymmetries may interact with EP-related power asymmetries resulting in a stronger effect of EP on women's health than on men's health (Hp.2). An alternative way of looking at the gender differential is to consider the interaction that precariousness might have with men's and women's gender identities. According to this view, the negative relationship between EP and health is weaker for women than for men (Hp.2a). In a society with a gendered division of labor and a strong link between masculine identities and stable and well-rewarded job—i.e., a job that confers the role of primary family provider—a male worker with precarious employment might violate the traditional male gender role. Men in precarious jobs may perceive themselves (and by others) as possessing a socially undesirable characteristic, which conflicts with the stereotypical idea of themselves as the male breadwinner. Engaging in behaviors that contradict stereotypical gender identity may decrease self-esteem and foster feelings of inferiority, helplessness, and jealousy, leading to poor health. I develop a new indicator of EP that empirically translates a definition of EP as a multidimensional and continuous phenomenon. I assume that EP is a latent construct composed of seven dimensions of insecurity chosen according to the theory and previous empirical research: Income insecurity, social insecurity, legal insecurity, employment insecurity, working-time insecurity, representation insecurity, worker's vulnerability. The seven dimensions are proxied by eight indicators available in the four waves of the SOEP dataset. The EP composite indicator is obtained by performing a multiple correspondence analysis (MCA) on the eight indicators. This approach aims to construct a summary scale in which all dimensions contribute jointly to the measured experience of precariousness and its health impact. Further, the relationship between EP and 'general self-perceived health' is estimated by applying ordered probit random-effects estimators and calculating average marginal effect (further AME). Then, to control for unobserved heterogeneity, I implement correlated random-effects models that add to the model the within-individual means of the time-varying independent variables. To test the significance of the gender differential, I add an interaction term between EP and gender in the fully adjusted model in the pooled sample. My correlated random-effects models showed EP's negative and substantial 'effect' on self-perceived health for both men and women. Although nonsignificant, the evidence seems in line with previous cross-sectional literature. It supports the hypothesis that employment precariousness could be detrimental to workers' health. Further, my results showed the crucial role of unobserved heterogeneity in shaping the health consequences of precarious employment. This is particularly important as evidence accumulates, yet it is still mostly descriptive. Moreover, my results revealed a substantial difference among men and women in the relationship between EP and health: when EP increases, the risk of experiencing poor health increases much more for men than for women. This evidence falsifies previous theory according to whom the gender differential is contingent on the structurally disadvantaged position of women in western societies. In contrast, they seem to confirm the idea that men in precarious work could experience role conflict to a larger extent than women, as their self-standard is supposed to be the stereotypical breadwinner worker with a good and well-rewarded job. Finally, results from the multiple correspondence analysis contribute to the methodological debate on precariousness, showing that a multidimensional and continuous indicator can express a latent variable of EP. All in all, complementarities are revealed in the results of unemployment and employment precariousness, which have two implications: Policy-makers need to be aware that the total costs of unemployment and precariousness go far beyond the economic and material realm penetrating other fundamental life domains such as individual health. Moreover, they need to balance the trade-off between protecting adequately unemployed people and fostering high-quality employment in reaction to the highlighted market pressures. In this sense, the further development of a (universalistic) welfare state certainly helps mitigate the adverse health effects of unemployment and, therefore, the future costs of both individuals' health and welfare spending. In addition, the presence of a working partner is crucial for reducing the health consequences of employment instability. Therefore, policies aiming to increase female labor market participation should be promoted, especially in those contexts where the welfare state is less developed. Moreover, my results support the significance of taking account of a gender perspective in health research. The findings of the three articles show that job loss, unemployment, and precarious employment, in general, have adverse effects on men's health but less or absent consequences for women's health. Indeed, this suggests the importance of labor and health policies that consider and further distinguish the specific needs of the male and female labor force in Europe. Nevertheless, a further implication emerges: the health consequences of employment instability and de-standardization need to be investigated in light of the gender arrangements and the transforming gender relationships in specific cultural and institutional contexts. My results indeed seem to suggest that women's health advantage may be a transitory phenomenon, contingent on the predominant gendered institutional and cultural context. As the structural difference between men's and women's position in society is eroded, egalitarianism becomes the dominant normative status, so will probably be the gender difference in the health consequences of job loss and precariousness. Therefore, while gender equality in opportunities and roles is a desirable aspect for contemporary societies and a political goal that cannot be postponed further, this thesis raises a further and maybe more crucial question: What kind of equality should be pursued to provide men and women with both good life quality and equal chances in the public and private spheres? In this sense, I believe that social and labor policies aiming to reduce gender inequality in society should focus on improving women's integration into the labor market, implementing policies targeting men, and facilitating their involvement in the private sphere of life. Equal redistribution of social roles could activate a crucial transformation of gender roles and the cultural models that sustain and still legitimate gender inequality in Western societies. KW - unemployment KW - employment precariousness KW - self-rated health KW - gender KW - family KW - welfare and gender regimes Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-536723 ER - TY - GEN A1 - Kliegl, Reinhold A1 - Masson, Michael E. J. A1 - Richter, Eike M. T1 - A linear mixed model analysis of masked repetition priming N2 - We examined individual differences in masked repetition priming by re-analyzing item-level response-time (RT) data from three experiments. Using a linear mixed model (LMM) with subjects and items specified as crossed random factors, the originally reported priming and word-frequency effects were recovered. In the same LMM, we estimated parameters describing the distributions of these effects across subjects. Subjects’ frequency and priming effects correlated positively with each other and negatively with mean RT. These correlation estimates, however, emerged only with a reciprocal transformation of RT (i.e., -1/RT), justified on the basis of distributional analyses. Different correlations, some with opposite sign, were obtained (1) for untransformed or logarithmic RTs or (2) when correlations were computed using within-subject analyses. We discuss the relevance of the new results for accounts of masked priming, implications of applying RT transformations, and the use of LMMs as a tool for the joint analysis of experimental effects and associated individual differences. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 247 Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-57073 ER - TY - JOUR A1 - Herold, Fabian A1 - Labott, Berit K. A1 - Grässler, Bernhard A1 - Halfpaap, Nicole A1 - Langhans, Corinna A1 - Müller, Patrick A1 - Ammar, Achraf A1 - Dordevic, Milos A1 - Hökelmann, Anita A1 - Müller, Notger Germar T1 - A Link between Handgrip Strength and Executive Functioning: A Cross-Sectional Study in Older Adults with Mild Cognitive Impairment and Healthy Controls JF - Healthcare : open access journal N2 - Older adults with amnestic mild cognitive impairment (aMCI) who in addition to their memory deficits also suffer from frontal-executive dysfunctions have a higher risk of developing dementia later in their lives than older adults with aMCI without executive deficits and older adults with non-amnestic MCI (naMCI). Handgrip strength (HGS) is also correlated with the risk of cognitive decline in the elderly. Hence, the current study aimed to investigate the associations between HGS and executive functioning in individuals with aMCI, naMCI and healthy controls. Older, right-handed adults with amnestic MCI (aMCI), non-amnestic MCI (naMCI), and healthy controls (HC) conducted a handgrip strength measurement via a handheld dynamometer. Executive functions were assessed with the Trail Making Test (TMT A&B). Normalized handgrip strength (nHGS, normalized to Body Mass Index (BMI)) was calculated and its associations with executive functions (operationalized through z-scores of TMT B/A ratio) were investigated through partial correlation analyses (i.e., accounting for age, sex, and severity of depressive symptoms). A positive and low-to-moderate correlation between right nHGS (rp (22) = 0.364; p = 0.063) and left nHGS (rp (22) = 0.420; p = 0.037) and executive functioning in older adults with aMCI but not in naMCI or HC was observed. Our results suggest that higher levels of nHGS are linked to better executive functioning in aMCI but not naMCI and HC. This relationship is perhaps driven by alterations in the integrity of the hippocampal-prefrontal network occurring in older adults with aMCI. Further research is needed to provide empirical evidence for this assumption. KW - MCI KW - hippocampal-prefrontal network KW - handgrip strength KW - exercise cognition KW - aging KW - brain health Y1 - 2022 U6 - https://doi.org/10.3390/healthcare10020230 SN - 2227-9032 VL - 10 SP - 1 EP - 14 PB - MDPI CY - Basel, Schweiz ET - 2 ER - TY - RPRT A1 - Šedová, Barbora A1 - Čizmaziová, Lucia A1 - Cook, Athene T1 - A meta-analysis of climate migration literature T2 - CEPA Discussion Papers N2 - The large literature that aims to find evidence of climate migration delivers mixed findings. This meta-regression analysis i) summarizes direct links between adverse climatic events and migration, ii) maps patterns of climate migration, and iii) explains the variation in outcomes. Using a set of limited dependent variable models, we meta-analyze thus-far the most comprehensive sample of 3,625 estimates from 116 original studies and produce novel insights on climate migration. We find that extremely high temperatures and drying conditions increase migration. We do not find a significant effect of sudden-onset events. Climate migration is most likely to emerge due to contemporaneous events, to originate in rural areas and to take place in middle-income countries, internally, to cities. The likelihood to become trapped in affected areas is higher for women and in low-income countries, particularly in Africa. We uniquely quantify how pitfalls typical for the broader empirical climate impact literature affect climate migration findings. We also find evidence of different publication biases. T3 - CEPA Discussion Papers - 29 KW - migration KW - climate change KW - meta-analysis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-499827 SN - 2628-653X IS - 29 ER - TY - JOUR A1 - Weise, Martin T1 - A model for teaching informatics to German secondary school students in English-language bilingual education JF - Commentarii informaticae didacticae : (CID) N2 - Informatics as a school subject has been virtually absent from bilingual education programs in German secondary schools. Most bilingual programs in German secondary education started out by focusing on subjects from the field of social sciences. Teachers and bilingual curriculum experts alike have been regarding those as the most suitable subjects for bilingual instruction – largely due to the intercultural perspective that a bilingual approach provides. And though one cannot deny the gain that ensues from an intercultural perspective on subjects such as history or geography, this benefit is certainly not limited to social science subjects. In consequence, bilingual curriculum designers have already begun to include other subjects such as physics or chemistry in bilingual school programs. It only seems a small step to extend this to informatics. This paper will start out by addressing potential benefits of adding informatics to the range of subjects taught as part of English-language bilingual programs in German secondary education. In a second step it will sketch out a methodological (= didactical) model for teaching informatics to German learners through English. It will then provide two items of hands-on and tested teaching material in accordance with this model. The discussion will conclude with a brief outlook on the chances and prerequisites of firmly establishing informatics as part of bilingual school curricula in Germany. Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64568 SN - 1868-0844 SN - 2191-1940 IS - 6 SP - 127 EP - 137 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Pornsawad, Pornsarp A1 - Sapsakul, Nantawan A1 - Böckmann, Christine T1 - A modified asymptotical regularization of nonlinear ill-posed problems JF - Mathematics N2 - In this paper, we investigate the continuous version of modified iterative Runge–Kutta-type methods for nonlinear inverse ill-posed problems proposed in a previous work. The convergence analysis is proved under the tangential cone condition, a modified discrepancy principle, i.e., the stopping time T is a solution of ∥𝐹(𝑥𝛿(𝑇))−𝑦𝛿∥=𝜏𝛿+ for some 𝛿+>𝛿, and an appropriate source condition. We yield the optimal rate of convergence. KW - nonlinear operator KW - regularization KW - discrepancy principle KW - asymptotic method KW - optimal rate Y1 - 2019 U6 - https://doi.org/10.3390/math7050419 SN - 2227-7390 VL - 7 PB - MDPI CY - Basel, Schweiz ET - 5 ER - TY - CHAP A1 - Vlugter, Peter A1 - Knott, Alistair T1 - A multi-speaker dialogue system for computer-aided language learning N2 - The main topic of this paper is how to configure a dialogue system to support computer-aided language learning. The paper also serves to introduce our new multi-speaker dialogue system, and highlight some of its novel features. Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10208 ER - TY - CHAP A1 - Herre, Heinrich A1 - Hummel, Axel T1 - A paraconsistent semantics for generalized logic programs N2 - We propose a paraconsistent declarative semantics of possibly inconsistent generalized logic programs which allows for arbitrary formulas in the body and in the head of a rule (i.e. does not depend on the presence of any specific connective, such as negation(-as-failure), nor on any specific syntax of rules). For consistent generalized logic programs this semantics coincides with the stable generated models introduced in [HW97], and for normal logic programs it yields the stable models in the sense of [GL88]. KW - paraconsistency KW - generalized logic programs KW - multi-valued logic Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41496 ER - TY - JOUR A1 - Spikes, Montrai A1 - Rodríguez-Silva, Rodet A1 - Bennett, Kerri-Ann A1 - Bräger, Stefan A1 - Josaphat, James A1 - Torres-Pineda, Patricia A1 - Ernst, Anja A1 - Havenstein, Katja A1 - Schlupp, Ingo A1 - Tiedemann, Ralph T1 - A phylogeny of the genus Limia (Teleostei: Poeciliidae) suggests a single-lake radiation nested in a Caribbean-wide allopatric speciation scenario JF - BMC Research Notes N2 - Objective The Caribbean is an important global biodiversity hotspot. Adaptive radiations there lead to many speciation events within a limited period and hence are particularly prominent biodiversity generators. A prime example are freshwater fish of the genus Limia, endemic to the Greater Antilles. Within Hispaniola, nine species have been described from a single isolated site, Lake Miragoâne, pointing towards extraordinary sympatric speciation. This study examines the evolutionary history of the Limia species in Lake Miragoâne, relative to their congeners throughout the Caribbean. Results For 12 Limia species, we obtained almost complete sequences of the mitochondrial cytochrome b gene, a well-established marker for lower-level taxonomic relationships. We included sequences of six further Limia species from GenBank (total N  = 18 species). Our phylogenies are in concordance with other published phylogenies of Limia. There is strong support that the species found in Lake Miragoâne in Haiti are monophyletic, confirming a recent local radiation. Within Lake Miragoâne, speciation is likely extremely recent, leading to incomplete lineage sorting in the mtDNA. Future studies using multiple unlinked genetic markers are needed to disentangle the relationships within the Lake Miragoâne clade. KW - Cytochrome b KW - Island biogeography KW - Fresh water fish KW - Phylogeny Y1 - 2021 U6 - https://doi.org/10.1186/s13104-021-05843-x SN - 1756-0500 VL - 14 SP - 1 EP - 8 PB - BMC Research Notes / Biomed Central CY - London ER - TY - JOUR A1 - Warschburger, Petra A1 - Petersen, Ann-Christin A1 - von Rezori, Roman Enzio A1 - Buchallik, Friederike A1 - Baumeister, Harald A1 - Holl, Reinhard A1 - Minden, Kirsten A1 - Müller-​Stierlin, Annabel Sandra A1 - Reinauer, Christina A1 - Staab, Doris A1 - COACH consortium, T1 - A prospective investigation of developmental trajectories of psychosocial adjustment in adolescents facing a chronic condition - study protocol of an observational, multi-center study JF - BMC Pediatrics N2 - Background Relatively little is known about protective factors and the emergence and maintenance of positive outcomes in the field of adolescents with chronic conditions. Therefore, the primary aim of the study is to acquire a deeper understanding of the dynamic process of resilience factors, coping strategies and psychosocial adjustment of adolescents living with chronic conditions. Methods/design We plan to consecutively recruit N = 450 adolescents (12–21 years) from three German patient registries for chronic conditions (type 1 diabetes, cystic fibrosis, or juvenile idiopathic arthritis). Based on screening for anxiety and depression, adolescents are assigned to two parallel groups – “inconspicuous” (PHQ-9 and GAD-7 < 7) vs. “conspicuous” (PHQ-9 or GAD-7 ≥ 7) – participating in a prospective online survey at baseline and 12-month follow-up. At two time points (T1, T2), we assess (1) intra- and interpersonal resiliency factors, (2) coping strategies, and (3) health-related quality of life, well-being, satisfaction with life, anxiety and depression. Using a cross-lagged panel design, we will examine the bidirectional longitudinal relations between resiliency factors and coping strategies, psychological adaptation, and psychosocial adjustment. To monitor Covid-19 pandemic effects, participants are also invited to take part in an intermediate online survey. Discussion The study will provide a deeper understanding of adaptive, potentially modifiable processes and will therefore help to develop novel, tailored interventions supporting a positive adaptation in youths with a chronic condition. These strategies should not only support those at risk but also promote the maintenance of a successful adaptation. Trial registration German Clinical Trials Register (DRKS), no. DRKS00025125. Registered on May 17, 2021. KW - Chronic conditions KW - Adolescents KW - Prospective KW - Quality of life KW - Resiliency KW - Coping KW - Protective factors KW - Type 1 diabetes KW - Juvenile idiopathic arthritis KW - Cystic fibrosis Y1 - 2021 U6 - https://doi.org/10.1186/s12887-021-02869-9 SN - 1471-2431 VL - 21 SP - 1 EP - 13 PB - BMC pediatrics CY - London ER - TY - JOUR A1 - Schmidt, Imanuel Clemens T1 - A Secular Tradition BT - Horace Kallen on American Democracy in the United States and Israel JF - PaRDeS : Journal of the Association for Jewish Studies in Germany JF - PaRDeS : Zeitschrift der Vereinigung für Jüdische Studien N2 - This article focuses on the social philosopher Horace Kallen and the revisions he made to the concept of cultural pluralism that he first developed in the early 20th century, applying it to postwar America and the young State of Israel. It shows how he opposed the assumption that the United States’ social order was based on a “Judeo-Christian tradition.” By constructing pluralism as a civil religion and carving out space for secular self-understandings in midcentury America, Kallen attempted to preserve the integrity of his earlier political visions, developed during World War I, of pluralist societies in the United States and Palestine within an internationalist global order. While his perspective on the State of Israel was largely shaped by his American experiences, he revised his approach to politically functionalizing religious traditions as he tested his American understanding of a secular, pluralist society against the political theology effective in the State of Israel. The trajectory of Kallen’s thought points to fundamental questions about the compatibility of American and Israeli understandings of religion’s function in society and its relation to political belonging, especially in light of their transnational connection through American Jewish support for the recently established state. KW - modern Jewish history KW - United States KW - Israel KW - 20th century KW - Horace Kallen KW - cultural pluralism KW - intellectual history KW - moderne jüdische Geschichte KW - USA KW - Israel KW - 20. Jahrhundert KW - Horace Kallen KW - kultureller Pluralismus KW - Geistesgeschichte Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-532868 SN - 978-3-86956-520-0 SN - 1614-6492 SN - 1862-7684 IS - 27 SP - 85 EP - 100 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - CHAP A1 - Goltz, Hans-Joachim A1 - Pieth, Norbert T1 - A tool for generating partition schedules of multiprocessor systems N2 - A deterministic cycle scheduling of partitions at the operating system level is supposed for a multiprocessor system. In this paper, we propose a tool for generating such schedules. We use constraint based programming and develop methods and concepts for a combined interactive and automatic partition scheduling system. This paper is also devoted to basic methods and techniques for modeling and solving this partition scheduling problem. Initial application of our partition scheduling tool has proved successful and demonstrated the suitability of the methods used. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41556 ER - TY - THES A1 - Stanke, Sandra T1 - AC electrokinetic immobilization of influenza viruses and antibodies on nanoelectrode arrays for on-chip immunoassays T1 - AC elektrokinetische Immobilisierung von Influenzaviren und Antikörpern auf Nanoelektrodenarrays für on-Chip Immunoassays N2 - In the present thesis, AC electrokinetic forces, like dielectrophoresis and AC electroosmosis, were demonstrated as a simple and fast method to functionalize the surface of nanoelectrodes with submicrometer sized biological objects. These nanoelectrodes have a cylindrical shape with a diameter of 500 nm arranged in an array of 6256 electrodes. Due to its medical relevance influenza virus as well as anti-influenza antibodies were chosen as a model organism. Common methods to bring antibodies or proteins to biosensor surfaces are complex and time-consuming. In the present work, it was demonstrated that by applying AC electric fields influenza viruses and antibodies can be immobilized onto the nanoelectrodes within seconds without any prior chemical modification of neither the surface nor the immobilized biological object. The distribution of these immobilized objects is not uniform over the entire array, it exhibits a decreasing gradient from the outer row to the inner ones. Different causes for this gradient have been discussed, such as the vortex-shaped fluid motion above the nanoelectrodes generated by, among others, electrothermal fluid flow. It was demonstrated that parts of the accumulated material are permanently immobilized to the electrodes. This is a unique characteristic of the presented system since in the literature the AC electrokinetic immobilization is almost entirely presented as a method just for temporary immobilization. The spatial distribution of the immobilized viral material or the anti-influenza antibodies at the electrodes was observed by either the combination of fluorescence microscopy and deconvolution or by super-resolution microscopy (STED). On-chip immunoassays were performed to examine the suitability of the functionalized electrodes as a potential affinity-based biosensor. Two approaches were pursued: A) the influenza virus as the bio-receptor or B) the influenza virus as the analyte. Different sources of error were eliminated by ELISA and passivation experiments. Hence, the activity of the immobilized object was inspected by incubation with the analyte. This resulted in the successful detection of anti-influenza antibodies by the immobilized viral material. On the other hand, a detection of influenza virus particles by the immobilized anti-influenza antibodies was not possible. The latter might be due to lost activity or wrong orientation of the antibodies. Thus, further examinations on the activity of by AC electric fields immobilized antibodies should follow. When combined with microfluidics and an electrical read-out system, the functionalized chips possess the potential to serve as a rapid, portable, and cost-effective point-of-care (POC) device. This device can be utilized as a basis for diverse applications in diagnosing and treating influenza, as well as various other pathogens. N2 - In der vorliegenden Arbeit wurden AC elektrokinetische Kräfte, wie die Dielektrophorese und die AC Elektroosmose, als einfache und schnelle Methode zur Funktionalisierung der Oberfläche von Nanoelektroden mit biologischen Objekten in Submikrometergröße demonstriert. Diese Nanoelektroden haben eine zylindrische Form mit einem Durchmesser von 500 nm und sind in einem Array aus 6256 Elektroden angeordnet. Aufgrund ihrer medizinischen Relevanz wurden Influenzaviren sowie anti-Influenza Antikörper als Modellorganismus ausgewählt. Gängige Methoden, um Antikörper oder Proteine auf Biosensoroberflächen zu bringen, sind komplex und zeitaufwändig. In der vorliegenden Arbeit wurde gezeigt, dass durch die Anwendung elektrischer Wechselfelder Influenzaviren und Antikörper innerhalb von Sekunden auf den Nanoelektroden immobilisiert werden können, ohne dass zuvor eine chemische Modifikation der Oberfläche noch des immobilisierten biologischen Objekts erforderlich ist. Die Verteilung dieser immobilisierten Objekte ist über das gesamte Array ungleichmäßig. Es kommt zur Ausbildung eines Gradienten, welcher von der äußeren zur den inneren Reihen hin abnimmt. Verschiedene Ursachen für diesen Gradienten wurden diskutiert, beispielsweise der Vortex-förmige Flüssigkeitsstrom über den Nanoelektroden, der unter anderem durch elektrothermische Flüssigkeitsbewegung erzeugt wird. Es wurde gezeigt, dass Teile des akkumulierten Materials dauerhaft an den Elektroden immobilisiert sind. Dies ist ein Alleinstellungsmerkmal des vorgestellten Systems, da in der Literatur die AC elektrokinetische Immobilisierung fast ausschließlich als Methode nur zur temporären Immobilisierung dargestellt wird. Die räumliche Verteilung des immobilisierten Virusmaterials bzw. der anti-Influenza Antikörper an den Elektroden wurde entweder durch die Kombination aus Fluoreszenzmikroskopie und Dekonvolution oder durch super-resolution Mikroskopie (STED) betrachtet. Es wurden On-Chip-Immunoassays durchgeführt, um die Eignung der funktionalisierten Elektroden für einen potenziellen affinitätsbasierten Biosensor zu untersuchen. Dabei wurden zwei Ansätze verfolgt: A) Influenzaviren als Biorezeptor oder B) Influenzavirus als Analyt. Verschiedene Fehlerquellen wurden mittels ELISA und Passivierungsexperimente eliminiert. Infolgedessen wurde die Aktivität der immobilisierten Objekte durch Inkubation mit dem Analyten überprüft. Dies führte zum erfolgreichen Nachweis von anti-Influenza Antikörpern mittels immobilisiertem Virusmaterial. Andererseits war ein Nachweis von Influenzaviruspartikeln durch die immobilisierten anti-Influenza Antikörper nicht möglich. Letzteres könnte auf einen Aktivitätsverlust oder eine falsche Ausrichtung der Antikörper zurückzuführen sein. Daher sollten weitere Untersuchungen zur Aktivität von durch elektrische Wechselfelder immobilisierte Antikörper folgen. In Kombination mit Mikrofluidik und einem elektrischen Auslesesystem besitzen die funktionalisierten Chips das Potenzial, als schnelle, tragbare und kostengünstige Point-of-Care-Einheit (POC) zu dienen. Dieses Einheit kann als Grundlage für vielfältige Anwendungen bei der Diagnose und Behandlung von Influenza und verschiedenen anderen Krankheitserregern genutzt werden. KW - AC electrokinetics KW - AC Elektrokinetik KW - AC electroosmosis KW - AC Elektroosmosis KW - dielectrophoresis KW - Dielektrophorese KW - virus KW - Virus KW - influenza KW - Influenza KW - antibody KW - Antikörper KW - nanoelectrodes KW - Nanoelektroden KW - lab-on-chip KW - lab-on-chip KW - LOC KW - LOC KW - point-of-care KW - point-of-care KW - POC KW - POC KW - immunoassay KW - Immunoassay Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-617165 ER - TY - RPRT A1 - Estrin, Saul A1 - Khavul, Susanna A1 - Kritikos, Alexander A1 - Löher, Jonas T1 - Access to digital finance BT - equity crowdfunding across countries and platforms T2 - CEPA Discussion Papers N2 - Financing entrepreneurship spurs innovation and economic growth. Digital financial platforms that crowdfund equity for entrepreneurs have emerged globally, yet they remain poorly understood. We model equity crowdfunding in terms of the relationship between the number of investors and the amount of money raised per pitch. We examine heterogeneity in the average amount raised per pitch that is associated with differences across three countries and seven platforms. Using a novel dataset of successful fundraising on the most prominent platforms in the UK, Germany, and the USA, we find the underlying relationship between the number of investors and the amount of money raised for entrepreneurs is loglinear, with a coefficient less than one and concave to the origin. We identify significant variation in the average amount invested in each pitch across countries and platforms. Our findings have implications for market actors as well as regulators who set competitive frameworks. T3 - CEPA Discussion Papers - 72 KW - equity crowdfunding KW - soft information KW - entrepreneurship KW - finance KW - financial access and inclusion Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-623261 SN - 2628-653X IS - 72 ER - TY - JOUR A1 - Göldel, Julia Marlen A1 - Kamrath, Clemens A1 - Minden, Kirsten A1 - Wiegand, Susanna A1 - Lanzinger, Stefanie A1 - Sengler, Claudia A1 - Weihrauch-Blüher, Susann A1 - Holl, Reinhard A1 - Tittel, Sascha René A1 - Warschburger, Petra T1 - Access to Healthcare for Children and Adolescents with a Chronic Health Condition during the COVID-19 Pandemic: First Results from the KICK-COVID Study in Germany JF - Children N2 - This study examines the access to healthcare for children and adolescents with three common chronic diseases (type-1 diabetes (T1D), obesity, or juvenile idiopathic arthritis (JIA)) within the 4th (Delta), 5th (Omicron), and beginning of the 6th (Omicron) wave (June 2021 until July 2022) of the COVID-19 pandemic in Germany in a cross-sectional study using three national patient registries. A paper-and-pencil questionnaire was given to parents of pediatric patients (<21 years) during the routine check-ups. The questionnaire contains self-constructed items assessing the frequency of healthcare appointments and cancellations, remote healthcare, and satisfaction with healthcare. In total, 905 parents participated in the T1D-sample, 175 in the obesity-sample, and 786 in the JIA-sample. In general, satisfaction with healthcare (scale: 0–10; 10 reflecting the highest satisfaction) was quite high (median values: T1D 10, JIA 10, obesity 8.5). The proportion of children and adolescents with canceled appointments was relatively small (T1D 14.1%, JIA 11.1%, obesity 20%), with a median of 1 missed appointment, respectively. Only a few parents (T1D 8.6%; obesity 13.1%; JIA 5%) reported obstacles regarding health services during the pandemic. To conclude, it seems that access to healthcare was largely preserved for children and adolescents with chronic health conditions during the COVID-19 pandemic in Germany. KW - chronic health condition KW - children and adolescents KW - health care KW - COVID-19 pandemic KW - diabetes KW - rheumatic diseases KW - obesity Y1 - 2022 U6 - https://doi.org/10.3390/children10010010 SN - 2227-9067 VL - 10 SP - 1 EP - 11 PB - MDPI CY - Basel, Schweiz ET - 1 ER - TY - THES A1 - Kellermann, Thorsten T1 - Accurate numerical relativity simulations of non-vacuumspace-times in two dimensions and applications to critical collapse T1 - Exakte numerisch relativistische Simulationen der Nicht-Vakuum-Raum-Zeit in zwei Dimensionen und deren Anwendung zu Problemen des kritischen Kollaps N2 - This Thesis puts its focus on the physics of neutron stars and its description with methods of numerical relativity. In the first step, a new numerical framework the Whisky2D code will be developed, which solves the relativistic equations of hydrodynamics in axisymmetry. Therefore we consider an improved formulation of the conserved form of these equations. The second part will use the new code to investigate the critical behaviour of two colliding neutron stars. Considering the analogy to phase transitions in statistical physics, we will investigate the evolution of the entropy of the neutron stars during the whole process. A better understanding of the evolution of thermodynamical quantities, like the entropy in critical process, should provide deeper understanding of thermodynamics in relativity. More specifically, we have written the Whisky2D code, which solves the general-relativistic hydrodynamics equations in a flux-conservative form and in cylindrical coordinates. This of course brings in 1/r singular terms, where r is the radial cylindrical coordinate, which must be dealt with appropriately. In the above-referenced works, the flux operator is expanded and the 1/r terms, not containing derivatives, are moved to the right-hand-side of the equation (the source term), so that the left hand side assumes a form identical to the one of the three-dimensional (3D) Cartesian formulation. We call this the standard formulation. Another possibility is not to split the flux operator and to redefine the conserved variables, via a multiplication by r. We call this the new formulation. The new equations are solved with the same methods as in the Cartesian case. From a mathematical point of view, one would not expect differences between the two ways of writing the differential operator, but, of course, a difference is present at the numerical level. Our tests show that the new formulation yields results with a global truncation error which is one or more orders of magnitude smaller than those of alternative and commonly used formulations. The second part of the Thesis uses the new code for investigations of critical phenomena in general relativity. In particular, we consider the head-on-collision of two neutron stars in a region of the parameter space where two final states a new stable neutron star or a black hole, lay close to each other. In 1993, Choptuik considered one-parameter families of solutions, S[P], of the Einstein-Klein-Gordon equations for a massless scalar field in spherical symmetry, such that for every P > P⋆, S[P] contains a black hole and for every P < P⋆, S[P] is a solution not containing singularities. He studied numerically the behavior of S[P] as P → P⋆ and found that the critical solution, S[P⋆], is universal, in the sense that it is approached by all nearly-critical solutions regardless of the particular family of initial data considered. All these phenomena have the common property that, as P approaches P⋆, S[P] approaches a universal solution S[P⋆] and that all the physical quantities of S[P] depend only on |P − P⋆|. The first study of critical phenomena concerning the head-on collision of NSs was carried out by Jin and Suen in 2007. In particular, they considered a series of families of equal-mass NSs, modeled with an ideal-gas EOS, boosted towards each other and varied the mass of the stars, their separation, velocity and the polytropic index in the EOS. In this way they could observe a critical phenomenon of type I near the threshold of black-hole formation, with the putative solution being a nonlinearly oscillating star. In a successive work, they performed similar simulations but considering the head-on collision of Gaussian distributions of matter. Also in this case they found the appearance of type-I critical behaviour, but also performed a perturbative analysis of the initial distributions of matter and of the merged object. Because of the considerable difference found in the eigenfrequencies in the two cases, they concluded that the critical solution does not represent a system near equilibrium and in particular not a perturbed Tolmann-Oppenheimer-Volkoff (TOV) solution. In this Thesis we study the dynamics of the head-on collision of two equal-mass NSs using a setup which is as similar as possible to the one considered above. While we confirm that the merged object exhibits a type-I critical behaviour, we also argue against the conclusion that the critical solution cannot be described in terms of equilibrium solution. Indeed, we show that, in analogy with what is found in, the critical solution is effectively a perturbed unstable solution of the TOV equations. Our analysis also considers fine-structure of the scaling relation of type-I critical phenomena and we show that it exhibits oscillations in a similar way to the one studied in the context of scalar-field critical collapse. N2 - Diese Arbeit legt seinen Schwerpunkt auf die Physik von Neutronensternen und deren Beschreibung mit Methoden der numerischen Relativitätstheorie. Im ersten Schritt wird eine neue numerische Umgebung, der Whisky2D Code entwickelt, dieser löst die relativistischen Gleichungen der Hydrodynamik in Axialymmetrie. Hierzu betrachten wir eine verbesserte Formulierung der sog. "flux conserved formulation" der Gleichungen. Im zweiten Teil wird der neue Code verwendet , um das kritische Verhalten zweier kollidierenden Neutronensternen zu untersuchen. In Anbetracht der Analogie, um Übergänge in der statistischen Physik Phase werden wir die Entwicklung der Entropie der Neutronensterne während des gesamten Prozesses betrachten. Ein besseres Verständnis der Evolution von thermodynamischen Größen, wie der Entropie in kritischer Prozess, sollte zu einem tieferen Verständnis der relativistischen Thermodynamik führen. Der Whisky2D Code, zur Lösung Gleichungen relativistischer Hydrodynamik wurde in einer „flux conserved form“ und in zylindrischen Koordinaten geschrieben. Hierdurch entstehen 1 / r singuläre Terme, wobei r der ist, die entsprechend behandelt werden müssen. In früheren Arbeiten, wird der Operator expandiert und die 1 / r spezifisch Therme auf die rechte Seite geschrieben, so dass die linke Seite eine Form annimmt, die identisch ist mit der kartesischen Formulierung. Wir nennen dies die Standard-Formulierung. Eine andere Möglichkeit ist, die Terme nicht zu expandieren, den und den 1/r Term in die Gleichung hinein zu ziehen. Wir nennen dies die Neue-Formulierung. Die neuen Gleichungen werden mit den gleichen Verfahren wie im kartesischen Fall gelöst. Aus mathematischer Sicht ist keine Unterschiede zwischen den beiden Formulierungen zu erwarten, erst die numerische Sicht zeigt die Unterschiede auf. Versuche zeigen, dass die Neue-Formulierung numerische Fehler um mehrere Größenordnungen reduziert. Der zweite Teil der Dissertation verwendet den neuen Code für die Untersuchung kritischer Phänomene in der allgemeinen Relativitätstheorie. Insbesondere betrachten wir die Kopf-auf-Kollision zweier Neutronensterne in einem Bereich des Parameter Raums, deren zwei mögliche Endzustände entweder einen neuen stabilen Neutronenstern oder ein Schwarzes Loch darstellen. Im Jahr 1993, betrachtete Choptuik Ein-Parameter-Familien von Lösungen, S [P], der Einstein-Klein-Gordon-Gleichung für ein masseloses Skalarfeld in sphärischer Symmetrie, so dass für jedes P> P ⋆, S[P] ein Schwarzes Loch enthalten ist und jedes P

2 arcsec); and 2) the relative variance of adjacent pixels in DEMs resampled to 30-m resolution (UTM projected). We translate results into their impact on hillslope and channel slope calculations, and we highlight the quality of the five DEMs. We find that the Copernicus DEM, which is based on a carefully edited commercial version of the TanDEM-X, provides the highest quality landscape representation, and should become the preferred DEM for topographic analysis in areas without sufficient coverage of higher-quality local DEMs. KW - DEM noise KW - Fourier analysis KW - TanDEM-X KW - ASTER GDEM KW - Copernicus DEM KW - WorldDEM KW - SRTM KW - ALOS World 3D Y1 - 2021 U6 - https://doi.org/10.3389/feart.2021.758606 SN - 2296-6463 SP - 1 EP - 24 PB - Frontiers Media CY - Lausanne, Schweiz ER - TY - THES A1 - Müller, Melanie J. I. T1 - Bidirectional transport by molecular motors T1 - Bidirektionaler Transport durch molekulare Motoren N2 - In biological cells, the long-range intracellular traffic is powered by molecular motors which transport various cargos along microtubule filaments. The microtubules possess an intrinsic direction, having a 'plus' and a 'minus' end. Some molecular motors such as cytoplasmic dynein walk to the minus end, while others such as conventional kinesin walk to the plus end. Cells typically have an isopolar microtubule network. This is most pronounced in neuronal axons or fungal hyphae. In these long and thin tubular protrusions, the microtubules are arranged parallel to the tube axis with the minus ends pointing to the cell body and the plus ends pointing to the tip. In such a tubular compartment, transport by only one motor type leads to 'motor traffic jams'. Kinesin-driven cargos accumulate at the tip, while dynein-driven cargos accumulate near the cell body. We identify the relevant length scales and characterize the jamming behaviour in these tube geometries by using both Monte Carlo simulations and analytical calculations. A possible solution to this jamming problem is to transport cargos with a team of plus and a team of minus motors simultaneously, so that they can travel bidirectionally, as observed in cells. The presumably simplest mechanism for such bidirectional transport is provided by a 'tug-of-war' between the two motor teams which is governed by mechanical motor interactions only. We develop a stochastic tug-of-war model and study it with numerical and analytical calculations. We find a surprisingly complex cooperative motility behaviour. We compare our results to the available experimental data, which we reproduce qualitatively and quantitatively. N2 - In biologischen Zellen transportieren molekulare Motoren verschiedenste Frachtteilchen entlang von Mikrotubuli-Filamenten. Die Mikrotubuli-Filamente besitzen eine intrinsische Richtung: sie haben ein "Plus-" und ein "Minus-"Ende. Einige molekulare Motoren wie Dynein laufen zum Minus-Ende, während andere wie Kinesin zum Plus-Ende laufen. Zellen haben typischerweise ein isopolares Mikrotubuli-Netzwerk. Dies ist besonders ausgeprägt in neuronalen Axonen oder Pilz-Hyphen. In diesen langen röhrenförmigen Ausstülpungen liegen die Mikrotubuli parallel zur Achse mit dem Minus-Ende zum Zellkörper und dem Plus-Ende zur Zellspitze gerichtet. In einer solchen Röhre führt Transport durch nur einen Motor-Typ zu "Motor-Staus". Kinesin-getriebene Frachten akkumulieren an der Spitze, während Dynein-getriebene Frachten am Zellkörper akkumulieren. Wir identifizieren die relevanten Längenskalen und charakterisieren das Stauverhalten in diesen Röhrengeometrien mit Hilfe von Monte-Carlo-Simulationen und analytischen Rechnungen. Eine mögliche Lösung für das Stauproblem ist der Transport mit einem Team von Plus- und einem Team von Minus-Motoren gleichzeitig, so dass die Fracht sich in beide Richtungen bewegen kann. Dies wird in Zellen tatsächlich beobachtet. Der einfachste Mechanismus für solchen bidirektionalen Transport ist ein "Tauziehen" zwischen den beiden Motor-Teams, das nur mit mechanischer Interaktion funktioniert. Wir entwickeln ein stochastisches Tauzieh-Modell, das wir mit numerischen und analytischen Rechnungen untersuchen. Es ergibt sich ein erstaunlich komplexes Motilitätsverhalten. Wir vergleichen unsere Resultate mit den vorhandenen experimentellen Daten, die wir qualitativ und quantitativ reproduzieren. KW - molekulare Motoren KW - bidirektionaler intrazellulärer Transport KW - Tauziehen KW - stochastische Prozesse KW - kooperative Phänomene KW - molecular motors KW - bidirectional intracellular transport KW - tug-of-war KW - stochastic processes KW - cooperative phenomena Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18715 ER - TY - INPR A1 - Schumacher, Jörg A1 - Seehafer, Norbert T1 - Bifurcation analysis of the plane sheet pinch N2 - A numerical bifurcation analysis of the electrically driven plane sheet pinch is presented. The electrical conductivity varies across the sheet such as to allow instability of the quiescent basic state at some critical Hartmann number. The most unstable perturbation is the two-dimensional tearing mode. Restricting the whole problem to two spatial dimensions, this mode is followed up to a time-asymptotic steady state, which proves to be sensitive to three-dimensional perturbations even close to the point where the primary instability sets in. A comprehensive three-dimensional stability analysis of the two-dimensional steady tearing-mode state is performed by varying parameters of the sheet pinch. The instability with respect to three-dimensional perturbations is suppressed by a sufficiently strong magnetic field in the invariant direction of the equilibrium. For a special choice of the system parameters, the unstably perturbed state is followed up in its nonlinear evolution and is found to approach a three-dimensional steady state. T3 - NLD Preprints - 56 Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14926 ER - TY - JOUR A1 - Yang, Jingdan A1 - Kim, Jae-Hyun A1 - Tuomainen, Outi A1 - Rattanasone, Nan Xu T1 - Bilingual Mandarin-English preschoolers’ spoken narrative skills and contributing factors BT - A remote online story-retell study JF - Frontiers in Psyhology N2 - This study examined the spoken narrative skills of a group of bilingual Mandarin–English speaking 3–6-year-olds (N = 25) in Australia, using a remote online story-retell task. Bilingual preschoolers are an understudied population, especially those who are speaking typologically distinct languages such as Mandarin and English which have fewer structural overlaps compared to language pairs that are typologically closer, reducing cross-linguistic positive transfer. We examined these preschoolers’ spoken narrative skills as measured by macrostructures (the global organization of a story) and microstructures (linguistic structures, e.g., total number of utterances, nouns, verbs, phrases, and modifiers) across and within each language, and how various factors such as age and language experiences contribute to individual variability. The results indicate that our bilingual preschoolers acquired spoken narrative skills similarly across their two languages, i.e., showing similar patterns of productivity for macrostructure and microstructure elements in both of their two languages. While chronological age was positively correlated with macrostructures in both languages (showing developmental effects), there were no significant correlations between measures of language experiences and the measures of spoken narrative skills (no effects for language input/output). The findings suggest that although these preschoolers acquire two typologically diverse languages in different learning environments, Mandarin at home with highly educated parents, and English at preschool, they displayed similar levels of oral narrative skills as far as these macro−/micro-structure measures are concerned. This study provides further evidence for the feasibility of remote online assessment of preschoolers’ narrative skills. KW - narrative skills KW - Mandarin-English bilinguals KW - preschoolers KW - macrostructure KW - microstructure Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.797602 SN - 1664-1078 VL - 13 PB - Frontiers Media SA CY - Lausanne, Schweiz ER - TY - GEN A1 - Kort, C. A. D. de A1 - Peter, Martin G. A1 - Koopmanschap, A. B. T1 - Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination N2 - The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10−7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 068 KW - Juvenile hormone KW - Leptinotarsa decemlineata KW - JH-III-specific carrier protein KW - enantioselectivity Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16777 ER - TY - THES A1 - Zhou, Shuo T1 - Biological evaluation and sulfation of polymer networks from glycerol glycidyl ether N2 - Cardiovascular diseases are the main cause of death worldwide, and their prevalence is expected to rise in the coming years. Polymer-based artificial replacements have been widely used for the treatment of cardiovascular diseases. Coagulation and thrombus formation on the interfaces between the materials and the human physiological environment are key issues leading to the failure of the medical device in clinical implantation. The surface properties of the materials have a strong influence on the protein adsorption and can direct the blood cell adhesion behavior on the interfaces. Furthermore, implant-associated infections will be induced by bacterial adhesion and subsequent biofilm formation at the implantation site. Thus, it is important to improve the hemocompatibility of an implant by altering the surface properties. One of the effective strategies is surface passivation to achieve protein/cell repelling ability to reduce the risk of thrombosis. This thesis consists of synthesis, functionalization, sterilization, and biological evaluation of bulk poly(glycerol glycidyl ether) (polyGGE), which is a highly crosslinked polyether-based polymer synthesized by cationic ring-opening polymerization. PolyGGE is hypothesized to be able to resist plasma protein adsorption and bacterial adhesion due to analogous chemical structure as polyethylene glycol and hyperbranched polyglycerol. Hydroxyl end groups of polyGGE provide possibilities to be functionalized with sulfates to mimic the anti-thrombogenic function of the endothelial glycocalyx. PolyGGE was synthesized by polymerization of the commercially available monomer glycerol glycidyl ether, which was characterized as a mixture of mono-, di- and tri-glycidyl ether. Cationic ring opening-polymerization of this monomer was carried out by ultraviolet (UV) initiation of the photo-initiator diphenyliodonium hexafluorophosphate. With the increased UV curing time, more epoxides in the side chains of the monomers participated in chemical crosslinking, resulting in an increase of Young’s modulus, while the value of elongation at break of polyGGE first increased due to the propagation of the polymer chains then decreased with the increase of crosslinking density. Eventually, the chain propagation can be effectively terminated by potassium hydroxide aqueous solution. PolyGGE exhibited different tensile properties in hydrated conditions at body temperature compared to the values in the dry state at room temperature. Both Young’s modulus and values of elongation at break were remarkably reduced when tested in water at 37 °C, which was above the glass transition temperature of polyGGE. At physiological conditions, entanglements of the ployGGE networks unfolded and the free volume of networks were replaced by water molecules as softener, which increased the mobility of the polymer chains, resulting in a lower Young’s modulus. Protein adsorption analysis was performed on polyGGE films with 30 min UV curing using an enzyme-linked immunosorbent assay. PolyGGE could effectively prevent the adsorption of human plasma fibrinogen, albumin, and fibronectin at the interface of human plasma and polyGGE films. The protein resistance of polyGGE was comparable to the negative controls: the hemocompatible polydimethylsiloxane (PDMS), showing its potential as a coating material for cardiovascular implants. Moreover, antimicrobial tests of bacterial activity using isothermal microcalorimetry and the microscopic image of direct bacteria culturing demonstrated that polyGGE could directly interfere biofilm formation and growth of both Gram-negative and antibiotic-resistant Gram-positive bacteria, indicating the potential application of polyGGE for combating the risk of hospital-acquired infections and preventing drug-resistant superbug spreading. To investigate its cell compatibility, polyGGE films were extracted by different solvents (ethanol, chloroform, acetone) and cell culture medium. Indirect cytotoxicity tests showed extracted polyGGE films still had toxic effects on L929 fibroblast cells. High-performance liquid chromatography/electrospray ionization mass spectrometry revealed the occurrence of organochlorine-containing compounds released during the polymer-cell culture medium interaction. A constant level of those organochlorine-containing compounds was confirmed from GGE monomer by a specific peak of C-Cl stretching in infrared spectra of GGE. This is assumed to be the main reason causing the increased cell membrane permeability and decreased metabolic activity, leading to cell death. Attempts as changing solvents were made to remove toxic substances, however, the release of these small molecules seems to be sluggish. The densely crosslinked polyGGE networks can possibly contribute to the trapping of organochlorine-containing compounds. These results provide valuable information for exploring the potentially toxic substances, leaching from polyGGE networks, and propose a feasible strategy for minimizing the cytotoxicity via reducing their crosslinking density. Sulfamic acid/ N-Methyl-2-pyrrolidone (NMP) were selected as the reagents for the sulfation of polyGGE surfaces. Fourier transform attenuated total reflection infrared spectroscopy (ATR-FT-IR) was used to monitor the functionalization kinetics and the results confirmed the successful sulfate grafting on the surface of polyGGE with the covalent bond -C-O-S-. X-ray photoelectron spectroscopy was used to determine the element composition on the surface and the cross-section of the functionalized polyGGE and sulfation within 15 min guarantees the sulfation only takes place on the surface while not occurring in the bulk of the polymer. The concentration of grafted sulfates increased with the increasing reaction time. The hydrophilicity of the surface of polyGGE was highly increased due to the increase of negatively charged end groups. Three sterilization techniques including autoclaving, gamma irradiation, and ethylene oxide (EtO) sterilization were used for polyGGE sulfates. Results from ATR-FT-IR and Toluidine Blue O quantitative assay demonstrated the total loss of the sulfates after autoclave sterilization, which was also confirmed by the increased water contact angle. Little influence on the concentration of sulfates was found for gamma-irradiated and autoclaving sterilized polyGGE sulfates. To investigate the thermal influence on polyGGE sulfates, one strategy was to use poly(hydroxyethyl acrylate) sulfates (PHEAS) for modeling. The thermogravimetric analysis profile of PHEAS demonstrated that sulfates are not thermally stable independent of the substrate materials and decomposition of sulfates occurs at around 100 °C. Although gamma irradiation also showed little negative effect on the sulfate content, the color change in the polyGGE sulfates indicates chemical or physical change might occur in the polymer. EtO sterilization was validated as the most suitable sterilization technique to maintain the chemical structure of polyGGE sulfates. In conclusion, the conducted work proved that bulk polyGGE can be used as an antifouling coating material and shows its antimicrobial potential. Sulfates functionalization can be effectively realized using sulfamic acid/NMP. EtO sterilization is the most suitable sterilization technique for grafted sulfates. Besides, this thesis also offers a good strategy for the analysis of toxic leachable substances using suitable physicochemical characterization techniques. Future work will focus on minimizing/eliminating the release of toxic substances via reducing the crosslinking density. Another interesting aspect is to study whether grafted sulfates can meet the need for anti-thrombogenicity. N2 - Herz-Kreislauf-Erkrankungen sind weltweit die Haupttodesursache, und es wird erwartet, dass ihre Prävalenz in den kommenden Jahren zunehmen wird. Künstlicher Ersatz auf Polymerbasis wird in großem Umfang für die Behandlung von Herz-Kreislauf-Erkrankungen eingesetzt. Gerinnung und Thrombenbildung an den Grenzflächen zwischen den Materialien und der menschlichen physiologischen Umgebung sind ein Hauptproblem, das zum Versagen des Medizinprodukts bei der klinischen Implantation führt. Die Oberflächeneigenschaften der Materialien haben einen starken Einfluss auf die Proteinadsorption und können das Adhäsionsverhalten von Blutzellen an den Grenzflächen steuern. Darüber hinaus werden Implantat-assoziierte Infektionen durch bakterielle Adhäsion und anschließende Biofilmbildung an der Implantationsstelle ausgelöst. Daher ist es wichtig, die Hämokompatibilität eines Implantats durch Veränderung der Oberflächeneigenschaften zu verbessern. Eine der wirksamen Strategien ist die Oberflächenpassivierung, um die Fähigkeit zur Protein-/Zellabweisung zu erreichen und so das Thromboserisiko zu verringern. Diese Arbeit befasst sich mit der Synthese, Funktionalisierung, Sterilisation und biologischen Bewertung von Poly(glycerin glycidyl ether) (polyGGE), einem stark vernetzten Polymer auf Polyetherbasis, das durch kationische Ringöffnungspolymerisation hergestellt wird. Es wird angenommen, dass PolyGGE aufgrund seiner ähnlichen chemischen Struktur wie Polyethylenglykol und hyperverzweigtes Polyglycerin der Adsorption von Plasmaproteinen und der Anhaftung von Bakterien widerstehen kann. Die Hydroxyl-Endgruppen von PolyGGE können mit Sulfaten funktionalisiert werden, um die antithrombogene Funktion der endothelialen Glykokalyx zu imitieren. PolyGGE wurde durch Polymerisation des kommerziell erhältlichen Monomers Glycerin Glycidyl ether synthetisiert, das als Mischung aus Mono-, Di- und Triglycidylether charakterisiert wurde. Die kationische Ringöffnungspolymerisation dieses Monomers wurde mit Hilfe des Photoinitiators Diphenyliodoniumhexafluorophosphat durch Ultraviolett (UV) ausgelöst. Mit zunehmender UV-Härtungszeit nahmen mehr Epoxide in den Seitenketten der Monomere an der chemischen Vernetzung teil, was zu einem Anstieg des Elastizitätsmoduls führte, während der Wert der Bruchdehnung von polyGGE zunächst aufgrund der Ausbreitung der Polymerketten anstieg und dann mit zunehmender Vernetzungsdichte abnahm. Schließlich kann die Kettenausbreitung durch wässrige Kaliumhydroxidlösung wirksam gestoppt werden. PolyGGE wies im hydratisierten Zustand bei Körpertemperatur andere Zugeigenschaften auf als im trockenen Zustand bei Raumtemperatur. Sowohl der Elastizitätsmodul als auch die Werte der Bruchdehnung waren deutlich reduziert, wenn sie in Wasser bei 37 °C getestet wurden, was oberhalb der Glasübergangstemperatur von PolyGGE lag. Unter physiologischen Bedingungen entfalteten sich die Verflechtungen der PolyGGE-Netzwerke und das freie Volumen der Netzwerke wurde durch Wassermoleküle als Weichmacher ersetzt, was die Mobilität der Polymerketten erhöhte und zu einem niedrigeren Elastizitätsmodul führte. Die Proteinadsorptionsanalyse wurde an PolyGGE-Filmen mit 30-minütiger UV-Härtung unter Verwendung eines Enzymimmunoassays durchgeführt. PolyGGE konnte die Adsorption von Fibrinogen, Albumin und Fibronektin aus menschlichem Plasma an der Grenzfläche zwischen menschlichem Plasma und PolyGGE-Filmen wirksam verhindern. Die Proteinresistenz von PolyGGE war vergleichbar mit den Negativkontrollen: dem hämokompatiblen Polydimethylsiloxan, was sein Potenzial als Beschichtungsmaterial für kardiovaskuläre Implantate zeigt. Darüber hinaus zeigten antimikrobielle Tests der bakteriellen Aktivität mittels isothermischer Mikrokalorimetrie und das mikroskopische Bild der direkten Bakterienkultur, dass PolyGGE die Biofilmbildung und das Wachstum sowohl von gramnegativen als auch von antibiotikaresistenten grampositiven Bakterien direkt stören kann, was auf die potenzielle Anwendung von PolyGGE zur Bekämpfung des Risikos von Krankenhausinfektionen und zur Verhinderung der Ausbreitung arzneimittelresistenter Superbugs hinweist. Um die Zellkompatibilität zu untersuchen, wurden polyGGE-Folien mit verschiedenen Lösungsmitteln (Ethanol, Chloroform, Aceton) und Zellkulturmedium extrahiert. Indirekte Zytotoxizitätstests zeigten, dass die extrahierten polyGGE-Filme immer noch eine toxische Wirkung auf L929-Fibroblastenzellen hatten. Die Hochleistungsflüssigkeitschromatographie/Elektrospray-Ionisations-Massenspektrometrie zeigte das Auftreten von chlororganischen Derivaten, die während der Interaktion zwischen Polymer und Zellkulturmedium freigesetzt wurden. Ein konstantes Niveau dieser chlororganischen Derivate wurde vom GGE-Monomer durch einen spezifischen C-Cl-Streckungspeak im Infrarotspektrum von GGE bestätigt. Es wird angenommen, dass dies der Hauptgrund für die erhöhte Permeabilität der Zellmembran und die verringerte Stoffwechselaktivität ist, was zum Zelltod führt. Es wurden Versuche unternommen, die Lösungsmittel zu wechseln, um die toxischen Substanzen zu entfernen, aber die Freisetzung dieser kleinen Moleküle scheint nur langsam zu erfolgen. Die dicht vernetzten polyGGE-Netzwerke können möglicherweise zum Einschluss chloridhaltiger Verbindungen beitragen. Diese Ergebnisse liefern wertvolle Informationen für die Erforschung potenzieller toxischer Substanzen, die aus PolyGGE-Netzwerken ausgewaschen werden, und schlagen eine praktikable Strategie zur Minimierung der Zytotoxizität durch Verringerung der Vernetzungsdichte vor. Als Reagenzien für die Sulfatierung von PolyGGE-Oberflächen wurden Sulfaminsäure und N-Methyl-2-Pyrrolidon (NMP) gewählt. Die Fourier-Transformations-Infrarotspektroskopie mit abgeschwächter Totalreflexion (ATR-FT-IR) wurde zur Überwachung der Funktionalisierungskinetik eingesetzt, und die Ergebnisse bestätigten die erfolgreiche Sulfatpfropfung auf der Oberfläche von PolyGGE mit der kovalenten Bindung -C-O-S-. Mit Hilfe der Röntgen-Photoelektronenspektroskopie wurde die Elementzusammensetzung auf der Oberfläche und der Querschnitt des funktionalisierten PolyGGE bestimmt, und die Sulfatierung innerhalb von 15 Minuten garantiert, dass die Sulfatierung nur auf der Oberfläche stattfindet, während sie in der Masse des Polymers nicht vorkommt. Die Konzentration der gepfropften Sulfate nahm mit zunehmender Reaktionszeit zu. Die Hydrophilie der Oberfläche von polyGGE wurde durch die Zunahme negativ geladener Endgruppen stark erhöht. Für die PolyGGE-Sulfate wurden drei Sterilisationstechniken verwendet: Autoklavieren, Gammastrahlenbestrahlung und Ethylenoxid (EtO)-Sterilisation. Die Ergebnisse der quantitativen ATR-FT-IR und Toluidinblau O-Untersuchung zeigten den vollständigen Verlust der Sulfate nach der Sterilisation im Autoklaven, was auch durch den erhöhten Wasserkontaktwinkel bestätigt wurde. Bei den mit Gammastrahlen und im Autoklaven sterilisierten PolyGGE-Sulfaten wurde nur ein geringer Einfluss auf die Sulfatkonzentration festgestellt. Um den thermischen Einfluss auf PolyGGE-Sulfate zu untersuchen, bestand eine Strategie darin, ein Poly(hydroxyethylacrylat)-Sulfat (PHEAS) für die Modellierung zu verwenden. Das Profil der thermogravimetrischen Analyse von PHEAS zeigte, dass Sulfate unabhängig von den Substratmaterialien thermisch nicht stabil sind und die Zersetzung der Sulfate bei etwa 100 °C stattfindet. Obwohl die Gammasterilisation ebenfalls kaum negative Auswirkungen auf den Sulfatgehalt hat, deutet die Farbveränderung der PolyGGE-Sulfate darauf hin, dass chemische oder physikalische Veränderungen im Polymer auftreten könnten. Die EtO-Sterilisation erwies sich als die am besten geeignete Sterilisationstechnik, um die chemische Struktur der PolyGGE-Sulfate zu erhalten. Zusammenfassend lässt sich sagen, dass die durchgeführte Arbeit bewiesen hat, dass PolyGGE als Antifouling-Beschichtungsmaterial verwendet werden kann und sein antimikrobielles Potenzial zeigt. Die Funktionalisierung der Sulfate kann mit Sulfaminsäure/NMP effektiv durchgeführt werden. Die EtO-Sterilisation ist die am besten geeignete Sterilisationstechnik für gepfropfte Sulfate. Darüber hinaus bietet diese Arbeit auch eine gute Strategie für die Analyse toxischer auslaugbarer Substanzen mit Hilfe geeigneter physikalisch-chemischer Charakterisierungstechniken. Zukünftige Arbeiten werden sich darauf konzentrieren, die Freisetzung toxischer Substanzen durch Verringerung der Vernetzungsdichte zu minimieren bzw. zu eliminieren. Ein weiterer interessanter Aspekt ist die Untersuchung, ob gepfropfte Sulfate den Anforderungen an die Anti-Thrombogenität gerecht werden können. KW - Sulfation KW - Antifouling KW - antimicrobial KW - Polyether Y1 - 2022 ER - TY - JOUR A1 - Quarmby, Andrew James A1 - Mönnig, Jamal A1 - Mugele, Hendrik A1 - Henschke, Jakob A1 - Kim, MyoungHwee A1 - Cassel, Michael A1 - Engel, Tilman T1 - Biomechanics and lower limb function are altered in athletes and runners with achilles tendinopathy compared with healthy controls: A systematic review JF - Frontiers in Sports and Active Living N2 - Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of “medial collapse”. Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn. KW - achilles tendinopathy KW - biomechanics KW - neuromuscular KW - kinetics KW - electromyography KW - athletes KW - runners KW - kinematics Y1 - 2023 U6 - https://doi.org/10.3389/fspor.2022.1012471 SN - 2624-9367 PB - Frontiers CY - Lausanne, Schweiz ER - TY - GEN A1 - Hocking, Brian T1 - Bridging boundaries: creating linkages : non-central governments and multilayered policy environments N2 - Observers of international politics have been conscious of the growing international involvement of non-central governments (NCGs), particularly in federal systems. These have been supplemented by the internationalisation of subnational actors in quasi-federal and even unitary states. One of the difficulties is that analysis has often been locked into the dominant paradigm debate in International Relations concerning who and who are not significant actors. Having briefly explored the nature of this changing environment, marked by a growing emphasis on access rather than control as a policy objective and the emergence of what is termed a 'catalytic diplomacy', the discussion focuses on the need for linkage between the levels of government in the pursuit of international as well as domestic policy goals. The nature of linkage mechanisms are discussed. Y1 - 1996 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11126 ER - TY - JOUR A1 - Benacka, Jan T1 - BubbleSort, SelectSort and InsertSort in Excel & Delphi BT - learning the Concepts in a Constructionist Way JF - Commentarii informaticae didacticae : (CID) N2 - A method is presented of acquiring the principles of three sorting algorithms through developing interactive applications in Excel. KW - spreadsheets KW - sorting KW - constructionism Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64636 SN - 1868-0844 SN - 2191-1940 IS - 6 SP - 153 EP - 154 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - BOOK A1 - Smirnov, Sergey A1 - Reijers, Hajo A. A1 - Nugteren, Thijs A1 - Weske, Mathias T1 - Business process model abstraction : theory and practice N2 - Business process management aims at capturing, understanding, and improving work in organizations. The central artifacts are process models, which serve different purposes. Detailed process models are used to analyze concrete working procedures, while high-level models show, for instance, handovers between departments. To provide different views on process models, business process model abstraction has emerged. While several approaches have been proposed, a number of abstraction use case that are both relevant for industry and scientifically challenging are yet to be addressed. In this paper we systematically develop, classify, and consolidate different use cases for business process model abstraction. The reported work is based on a study with BPM users in the health insurance sector and validated with a BPM consultancy company and a large BPM vendor. The identified fifteen abstraction use cases reflect the industry demand. The related work on business process model abstraction is evaluated against the use cases, which leads to a research agenda. T3 - Technische Berichte des Hasso-Plattner-Instituts für Digital Engineering an der Universität Potsdam - 35 Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41782 SN - 978-3-86956-054-0 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - THES A1 - Witt, Tanja Ivonne T1 - Camera Monitoring at volcanoes T1 - Kameramonitoring an Vulkanen BT - Identification and characterization of lava fountain activity and near-vent processes and their relevance for early warning systems BT - Identifikation und Charakterizierung der Aktivität von Lavafontänen und Near-Vent Prozesse und deren Relevanz für Frühwarnsysteme N2 - Basaltic fissure eruptions, such as on Hawai'i or on Iceland, are thought to be driven by the lateral propagation of feeder dikes and graben subsidence. Associated solid earth processes, such as deformation and structural development, are well studied by means of geophysical and geodetic technologies. The eruptions themselves, lava fountaining and venting dynamics, in turn, have been much less investigated due to hazardous access, local dimension, fast processes, and resulting poor data availability. This thesis provides a detailed quantitative understanding of the shape and dynamics of lava fountains and the morphological changes at their respective eruption sites. For this purpose, I apply image processing techniques, including drones and fixed installed cameras, to the sequence of frames of video records from two well-known fissure eruptions in Hawai'i and Iceland. This way I extract the dimensions of multiple lava fountains, visible in all frames. By putting these results together and considering the acquisition times of the frames I quantify the variations in height, width and eruption velocity of the lava fountains. Then I analyse these time-series in both time and frequency domains and investigate the similarities and correlations between adjacent lava fountains. Following this procedure, I am able to link the dynamics of the individual lava fountains to physical parameters of the magma transport in the feeder dyke of the fountains. The first case study in this thesis focuses on the March 2011 Pu'u'O'o eruption, Hawai'i, where a continuous pulsating behaviour at all eight lava fountains has been observed. The lava fountains, even those from different parts of the fissure that are closely connected, show a similar frequency content and eruption behaviour. The regular pattern in the heights of lava fountain suggests a controlling process within the magma feeder system like a hydraulic connection in the underlying dyke, affecting or even controlling the pulsating behaviour. The second case study addresses the 2014-2015 Holuhraun fissure eruption, Iceland. In this case, the feeder dyke is highlighted by the surface expressions of graben-like structures and fault systems. At the eruption site, the activity decreases from a continuous line of fire of ~60 vents to a limited number of lava fountains. This can be explained by preferred upwards magma movements through vertical structures of the pre-eruptive morphology. Seismic tremors during the eruption reveal vent opening at the surface and/or pressure changes in the feeder dyke. The evolving topography of the cinder cones during the eruption interacts with the lava fountain behaviour. Local variations in the lava fountain height and width are controlled by the conduit diameter, the depth of the lava pond and the shape of the crater. Modelling of the fountain heights shows that long-term eruption behaviour is controlled mainly by pressure changes in the feeder dyke. This research consists of six chapters with four papers, including two first author and two co-author papers. It establishes a new method to analyse lava fountain dynamics by video monitoring. The comparison with the seismicity, geomorphologic and structural expressions of fissure eruptions shows a complex relationship between focussed flow through dykes, the morphology of the cinder cones, and the lava fountain dynamics at the vents of a fissure eruption. N2 - Basaltische Spalteneruptionen, wie auf Hawaii oder Island, werden vermutlich durch die laterale Ausbreitung von Förderdikes und damit verbundener Grabenbildung verursacht. Prozesse der festen Erde sind mittels geophysikalischer und geodätischer Technologien gut erforscht. Die Ausbrüche selbst, d.h. die Lavafontä}nen und die Ventdynamik wiederum wurden aufgrund des gefährlichen Zugangs, der lokalen Dimension, der schnellen Prozesse und der daraus resultierenden schlechten Datenverfügbarkeit kaum untersucht. Diese Arbeit liefert ein detailliertes quantitatives Verständnis über Form und Dynamik von Lavafontänen und der morphologischen Veränderungen an ihren jeweiligen Eruptionsstellen. Mittels Bildverarbeitungstechniken, einschließlich Dronen und festen Kameras, wurden von mir die Videoframes von zwei bekannten Spaltausbrüchen auf Hawaii und Island ausgewertet. Auf diese Weise extrahiere ich die Dimensionen mehrerer Lavafontänen, die in allen Frames sichtbar sind. Durch die Zusammenstellung dieser Ergebnisse und unter Berücksichtigung der Erfassungszeiten quantifiziere ich die Schwankungen in Höhe, Breite und Eruptionsgeschwindigkeit. Dann analysiere ich diese Zeitreihen im Zeit- und Frequenzbereich und untersuche die Ähnlichkeiten und Zusammenhänge zwischen benachbarten Lavafontänen. Anschließend verknüpfte ich die Dynamik der einzelnen Lavafontänen mit den physikalischen Parametern des Magmatransports im Förderdike. Die erste Fallstudie dieser Arbeit konzentriert sich auf die Pu'u'O'o Ausbruch, Hawaii im März 2011, bei der ein kontinuierliches pulsierendes Verhalten an allen Lavafontänen beobachtet werden konnte. Lavafontänen verschiedener Teilsegmenten der Spalte sind eng miteinander verbunden, sie weisen Ähnlichkeiten im Frequenzgehalt und Ausbruchsverhalten auf. Das regelmäßige Muster in den Lavafontänenhöhen deutet auf eine hydraulische Verbindung im darunter liegenden Dike als steuernden Prozess innerhalb des Magma-Fördersystems hin. Die zweite Fallstudie befasst sich mit dem Holuhraun-Ausbruch 2014/2015. In diesem Fall wird der horizontale Förderdike durch grabenartige Strukturen und Bruchsysteme an der Oberfläche hervorgehoben. An der Ausbruchsstelle nimmt die Aktivität von einer kontinuierlichen Feuerlinie auf einzelne Lavafontänen ab. Dies lässt sich durch eine bevorzugte Aufwärtsbewegung des Magmas durch vertikale Strukturen der prä-eruptiven Morphologie erklären. Seismische Erschütterungen während des Ausbruchs zeigen Ventöffnungen an der Oberfläche und/oder Druckveränderungen im Förderdike. Die sich während des Ausbruchs entwickelnde Topographie der Schlackenkegel interagiert mit dem Verhalten der Lavafontänen. Lokale Schwankungen in Höhe und Breite der Lavafontäne werden jedoch durch den Schlotdurchmesser, die Tiefe des Lavaponds und die Form des Kraters gesteuert. Die Modellierung der Fontänenhöhe zeigt, dass das langfristige Ausbruchsverhalten vor allem durch Druckänderungen im Förderdike gesteuert wird. Diese Forschungsarbeit besteht aus sechs Kapiteln mit je zwei Papern als Erst- bzw. Co-Autor. Es etabliert eine neue Methode zur Analyse der Dynamik von Lavafontänen durch Videoüberwachung. Der Vergleich mit der Seismizität, den geomorphologischen und strukturellen Ausprägungen von Spalteneruptionen zeigt einen komplexen Zusammenhang zwischen der Dikeströmung, der Vulkanmorphologie und der Dynamik der Lavafontänen an einer Spalteneruption. KW - volcanology KW - Spalteneruption KW - fissure eruption KW - Vulkanologie KW - lava fountains KW - video analysis KW - basaltic volcanoes KW - Lavafontänen KW - Videoanalyse KW - Basalt-Vulkane Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-421073 ER - TY - GEN A1 - Howald, Markus A1 - Elsenbeer, Helmut A1 - Laczko, Endre A1 - Schlunegger, Urs Peter T1 - Capillary electrophoresis as a fast and universal tool in soil analysis N2 - Fast analysis of different species of molecules in soils is investigated by capillary electrophoresis (CE). Several CE techniques for the analysis of inorganic ions and carbohydrates have been tested. With regard to the intents of pedologists and the usually large number of soil analyses a bundle of CE systems is proposed, capable of effecting time-saving soil analyses. Adapted electrolyte systems recently published and new separation systems are described. Examples of the application of these methods to two different soil samples are presented. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 070 KW - capillary electrophoresis KW - soil analysis KW - UV-detection KW - inorganic ions KW - monosaccharides Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16913 ER - TY - THES A1 - Galushchinskiy, Alexey T1 - Carbon nitride: a flexible platform for net-oxidative and net-neutral photocatalysis BT - Kohlenstoffnitrid: Eine flexible Plattform für netzoxidative und netzneutrale Photokatalyse N2 - Solar photocatalysis is the one of leading concepts of research in the current paradigm of sustainable chemical industry. For actual practical implementation of sunlight-driven catalytic processes in organic synthesis, a cheap, efficient, versatile and robust heterogeneous catalyst is necessary. Carbon nitrides are a class of organic semiconductors who are known to fulfill these requirements. First, current state of solar photocatalysis in economy, industry and lab research is overviewed, outlining EU project funding, prospective synthetic and reforming bulk processes, small scale solar organic chemistry, and existing reactor designs and prototypes, concluding feasibility of the approach. Then, the photocatalytic aerobic cleavage of oximes to corresponding aldehydes and ketones by anionic poly(heptazine imide) carbon nitride is discussed. The reaction provides a feasible method of deprotection and formation of carbonyl compounds from nitrosation products and serves as a convenient model to study chromoselectivity and photophysics of energy transfer in heterogeneous photocatalysis. Afterwards, the ability of mesoporous graphitic carbon nitride to conduct proton-coupled electron transfer was utilized for the direct oxygenation of 1,3-oxazolidin-2-ones to corresponding 1,3-oxazlidine-2,4-diones. This reaction provides an easier access to a key scaffold of diverse types of drugs and agrochemicals. Finally, a series of novel carbon nitrides based on poly(triazine imide) and poly(heptazine imide) structure was synthesized from cyanamide and potassium rhodizonate. These catalysts demonstrated a good performance in a set of photocatalytic benchmark reactions, including aerobic oxidation, dual nickel photoredox catalysis, hydrogen peroxide evolution and chromoselective transformation of organosulfur precursors. Concluding, the scope of carbon nitride utilization for net-oxidative and net-neutral photocatalytic processes was expanded, and a new tunable platform for catalyst synthesis was discovered. N2 - Die solare Photokatalyse ist eines der führenden Forschungskonzepte im aktuellen Paradigma der nachhaltigen chemischen Industrie. Für die praktische Umsetzung von sonnenlichtgetriebenen katalytischen Prozessen in der organischen Synthese ist ein billiger, effizienter, vielseitiger und robuster heterogener Katalysator erforderlich. Kohlenstoffnitride sind eine Klasse von organischen Halbleitern, von denen bekannt ist, dass sie diese Anforderungen erfüllen. Zunächst wird ein Überblick über den aktuellen Stand der solaren Photokatalyse in Wirtschaft, Industrie und Laborforschung gegeben, wobei die Finanzierung von EU-Projekten, künftige Synthese- und Reformierungsprozesse in großen Mengen, organische Solarchemie in kleinem Maßstab sowie bestehende Reaktorkonstruktionen und -prototypen beschrieben und die Durchführbarkeit des Ansatzes erläutert werden. Anschließend wird die photokatalytische aerobe Spaltung von Oximen in die entsprechenden Aldehyde und Ketone durch anionisches Poly(heptazinimid)-Kohlenstoffnitrid diskutiert. Die Reaktion stellt eine praktikable Methode zur Entschützung und Bildung von Carbonylverbindungen aus Nitrosierungsprodukten dar und dient als geeignetes Modell zur Untersuchung der Chromoselektivität und der Photophysik der Energieübertragung in der heterogenen Photokatalyse. Anschließend wurde die Fähigkeit von mesoporösem graphitischem Kohlenstoffnitrid, protonengekoppelten Elektronentransfer zu leiten, für die direkte Oxygenierung von 1,3-Oxazolidin-2-onen zu den entsprechenden 1,3-Oxazlidin-2,4-Dionen genutzt. Diese Reaktion ermöglicht einen leichteren Zugang zu einem wichtigen Gerüst für verschiedene Arten von Medikamenten und Agrochemikalien. Schließlich wurde eine Reihe neuartiger Kohlenstoffnitride auf der Basis von Poly(triazinimid)- und Poly(heptazinimid)-Strukturen aus Cyanamid und Kaliumrhodizonat synthetisiert. Diese Katalysatoren zeigten eine gute Leistung in einer Reihe von photokatalytischen Benchmark-Reaktionen, einschließlich aerober Oxidation, dualer Nickel-Photoredox-Katalyse, Wasserstoffperoxid-Evolution und chromoselektiver Umwandlung von Organoschwefel-Vorläufern. Abschließend wurde der Anwendungsbereich von Kohlenstoffnitrid für netzoxidative und netzneutrale photokatalytische Prozesse erweitert und eine neue abstimmbare Plattform für die Katalysatorsynthese entdeckt. KW - carbon nitrides KW - Kohlenstoffnitriden KW - heterogeneous photocatalysis KW - heterogene Photokatalyse KW - organic synthesis KW - organische Synthese Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-610923 ER - TY - GEN A1 - Peter, Martin G. A1 - Andersen, Svend Olav A1 - Hartmann, Rudolf A1 - Miessner, Merle A1 - Roepstorff, Peter T1 - Catecholamine-protein conjugates : isolation of 4-phenylphenoxazin-2-ones from oxidative coupling of N-acetyldopamine with alipathic amino acids N2 - 4-Phenylphenoxazinones were isolated after biomimetic oxidation, using diphenoloxidases of insect cuticle, mushroom tyrosinase, or after autoxidation of N-acetyldopamine (Image ) in the presence of β-alanine, β-alanine methyl ester or N-acetyl-L-lysine. They are formed presumably by addition of 2-aminoalkyl-5-alkylphenols to the o-quinone of biphenyltetrol which, in turn, arises from oxidative coupling of. The structures of present the first examples for the assembly of reasonably stable intermediates in the rather complex process of chemical modifications of aliphatic amino acid residues by o-quinones. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 062 Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17571 ER - TY - THES A1 - Behrens, Ricarda T1 - Causes for slow weathering and erosion in the steep, warm, monsoon-subjected Highlands of Sri Lanka T1 - Ursache von langsamer Verwitterung und Erosion im steilen, warmen und Monsun-beeinflussten Hochland von Sri Lanka N2 - In the Highlands of Sri Lanka, erosion and chemical weathering rates are among the lowest for global mountain denudation. In this tropical humid setting, highly weathered deep saprolite profiles have developed from high-grade metamorphic charnockite during spheroidal weathering of the bedrock. The spheroidal weathering produces rounded corestones and spalled rindlets at the rock-saprolite interface. I used detailed textural, mineralogical, chemical, and electron-microscopic (SEM, FIB, TEM) analyses to identify the factors limiting the rate of weathering front advance in the profile, the sequence of weathering reactions, and the underlying mechanisms. The first mineral attacked by weathering was found to be pyroxene initiated by in situ Fe oxidation, followed by in situ biotite oxidation. Bulk dissolution of the primary minerals is best described with a dissolution – re-precipitation process, as no chemical gradients towards the mineral surface and sharp structural boundaries are observed at the nm scale. Only the local oxidation in pyroxene and biotite is better described with an ion by ion process. The first secondary phases are oxides and amorphous precipitates from which secondary minerals (mainly smectite and kaolinite) form. Only for biotite direct solid state transformation to kaolinite is likely. The initial oxidation of pyroxene and biotite takes place in locally restricted areas and is relatively fast: log J = -11 molmin/(m2 s). However, calculated corestone-scale mineral oxidation rates are comparable to corestone-scale mineral dissolution rates: log R = -13 molpx/(m2 s) and log R = -15 molbt/(m2 s). The oxidation reaction results in a volume increase. Volumetric calculations suggest that this observed oxidation leads to the generation of porosity due to the formation of micro-fractures in the minerals and the bedrock allowing for fluid transport and subsequent dissolution of plagioclase. At the scale of the corestone, this fracture reaction is responsible for the larger fractures that lead to spheroidal weathering and to the formation of rindlets. Since these fractures have their origin from the initial oxidational induced volume increase, oxidation is the rate limiting parameter for weathering to take place. The ensuing plagioclase weathering leads to formation of high secondary porosity in the corestone over a distance of only a few cm and eventually to the final disaggregation of bedrock to saprolite. As oxidation is the first weathering reaction, the supply of O2 is a rate-limiting factor for chemical weathering. Hence, the supply of O2 and its consumption at depth connects processes at the weathering front with erosion at the surface in a feedback mechanism. The strength of the feedback depends on the relative weight of advective versus diffusive transport of O2 through the weathering profile. The feedback will be stronger with dominating diffusive transport. The low weathering rate ultimately depends on the transport of O2 through the whole regolith, and on lithological factors such as low bedrock porosity and the amount of Fe-bearing primary minerals. In this regard the low-porosity charnockite with its low content of Fe(II) bearing minerals impedes fast weathering reactions. Fresh weatherable surfaces are a pre-requisite for chemical weathering. However, in the case of the charnockite found in the Sri Lankan Highlands, the only process that generates these surfaces is the fracturing induced by oxidation. Tectonic quiescence in this region and low pre-anthropogenic erosion rate (attributed to a dense vegetation cover) minimize the rejuvenation of the thick and cohesive regolith column, and lowers weathering through the feedback with erosion. N2 - Erosions- und chemische Verwitterungsraten im srilankischen Hochland gehören zu den langsamsten der globalen Gebirgsdenudationsraten. In diesem tropischen, humiden Gebiet entwickelten sich mächtige Verwitterungsprofile – sogenannte Saprolite – auf spheroidal verwittertem, hochgradig metamorphen Charnockit. Spheroidale Verwitterung führt zu abgerundeten „corestones“ mit abgesplitterten Rinden („rindlets“) an der Gesteins – Saprolit Grenze. Zur Identifizierung der ratenlimitierenden Faktoren des Fortschreiten der Verwitterungsfront, der Sequenz der Verwitterungsreaktionen und der dahinterliegenden Mechanismen nutzte ich detaillierte gesteinsstrukturelle, mineralogische, chemische und elektronenmikroskopische (SEM, FIB, TEM) Analysemethoden. Die initiale Verwitterung beginnt mit lokal begrenzter in situ Oxidation in Pyroxen, gefolgt von in situ Oxidation von Biotit. Die Auflösung der Minerale wird am besten durch einen Auflöse – Wiederausfällungs-prozess beschrieben, da zur Mineralgrenze hin keine chemischen Gradienten, dafür aber auf der nm-Skala scharfe strukturelle Grenzen zu beobachten sind. Die ersten ausfallenden Sekundärphasen sind Oxide und amorphe Phasen aus denen sich Sekundärmineral (hauptsächlich Smectit und Kaolinit) bilden. Für Biotit ist auch eine direkte Umwandlung im Festzustand zu Kaolinit möglich. Die initiale Pyroxen- und Biotitoxidation ist relativ schnell: log J = -11 molmin/(m2 s). Berechnete Oxidationsraten auf der corestone-Skala (cm) sind vergleichbar zu Auflöseraten auf derselben Skala: log R = -13 molpx/(m2 s) und log R = -15 molbt/(m2 s). Volumetrische Berechnungen führen zum Schluss, dass die Oxidation mit einhergehender Volumenzunahme zur Entwicklung von Mikrofrakturen in den Mineralen und dem Gesamtgestein führt. Diese begünstigen Fluidtransport und damit einhergehende Plagioklasverwitterung. Des Weiteren ist diese Oxidationsreaktion verantwortlich für die Entstehung der Frakturen bei spheroidaler Verwitterung des Gesteins, welche die „rindlets“ vom „corestone“ abgrenzen. Daraus kann geschlossen werden, dass in situ Oxidation der ratenlimitierende Prozess bei der Verwitterung ist. Plagioklasverwitterung führt zu einer hohen Porositätszunahme und der endgültigen Umwandlung von Gestein zu Saprolit. Da Oxidation die erste Verwitterungsreaktion ist, verbinden die Zuführung und der Verbrauch von O2 zur, beziehungsweise an die Verwitterungsfront Erosion an der Oberfläche mit Prozessen an der Verwitterungsfront über einen Feedbackmechanismus. Daher hängt die langsame Verwitterungsrate letztlich vom Sauerstofftransport durch das Verwitterungsprofil und von lithologischen Faktoren des Charnockit wie zum Beispiel geringe Gesteinsporosität und/oder wenige Fe(II)-haltige Primärminerale ab. Des Weiteren ist der einzige Prozess im Charnockit der frische verwitterbare Oberflächen (eine Voraussetzung für chemische Verwitterung) generiert die oxidations-induzierte Frakturierung. Darüber hinaus minimieren die Abwesenheit von tektonischer Aktivität und geringe prä-anthropogene Erosionsraten in dieser Region den Abtrag des mächtigen und kohäsiven Verwitterungsprofils und somit über den beschriebenen Feedback auch die chemische Verwitterungsrate. KW - Sri Lanka KW - chemical weathering KW - erosion KW - saprolite KW - weathering feedback KW - charnockite KW - critical zone KW - mineral weathering reactions KW - Sri Lanka KW - chemische Verwitterung KW - Erosion KW - Saprolit KW - Verwitterungsfeedback KW - Charnockit KW - kritische Zone KW - Mineralverwitterungsreaktionen Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408503 ER - TY - THES A1 - Breitenbach, Sebastian Franz Martin T1 - Changes in monsoonal precipitation and atmospheric circulation during the Holocene reconstructed from stalagmites from Northeastern India T1 - Veränderungen monsunalen Niederschlages und atmosphärischer Zirkulation während des Holozäns, rekonstruiert aus Stalagmiten aus Nordostindien N2 - Recent years witnessed a vast advent of stalagmites as palaeoclimate archives. The multitude of geochemical and physical proxies and a promise of a precise and accurate age model greatly appeal to palaeoclimatologists. Although substantial progress was made in speleothem-based palaeoclimate research and despite high-resolution records from low-latitudinal regions, proving that palaeo-environmental changes can be archived on sub-annual to millennial time scales our comprehension of climate dynamics is still fragmentary. This is in particular true for the summer monsoon system on the Indian subcontinent. The Indian summer monsoon (ISM) is an integral part of the intertropical convergence zone (ITCZ). As this rainfall belt migrates northward during boreal summer, it brings monsoonal rainfall. ISM strength depends however on a variety of factors, including snow cover in Central Asia and oceanic conditions in the Indic and Pacific. Presently, many of the factors influencing the ISM are known, though their exact forcing mechanism and mutual relations remain ambiguous. Attempts to make an accurate prediction of rainfall intensity and frequency and drought recurrence, which is extremely important for South Asian countries, resemble a puzzle game; all interaction need to fall into the right place to obtain a complete picture. My thesis aims to create a faithful picture of climate change in India, covering the last 11,000 ka. NE India represents a key region for the Bay of Bengal (BoB) branch of the ISM, as it is here where the monsoon splits into a northwestward and a northeastward directed arm. The Meghalaya Plateau is the first barrier for northward moving air masses and receives excessive summer rainfall, while the winter season is very dry. The proximity of Meghalaya to the Tibetan Plateau on the one hand and the BoB on the other hand make the study area a key location for investigating the interaction between different forcings that governs the ISM. A basis for the interpretation of palaeoclimate records, and a first important outcome of my thesis is a conceptual model which explains the observed pattern of seasonal changes in stable isotopes (d18O and d2H) in rainfall. I show that although in tropical and subtropical regions the amount effect is commonly called to explain strongly depleted isotope values during enhanced rainfall, alone it cannot account for observed rainwater isotope variability in Meghalaya. Monitoring of rainwater isotopes shows no expected negative correlation between precipitation amount and d18O of rainfall. In turn I find evidence that the runoff from high elevations carries an inherited isotopic signature into the BoB, where during the ISM season the freshwater builds a strongly depleted plume on top of the marine water. The vapor originating from this plume is likely to memorize' and transmit further very negative d18O values. The lack of data does not allow for quantication of this plume effect' on isotopes in rainfall over Meghalaya but I suggest that it varies on seasonal to millennial timescales, depending on the runoff amount and source characteristics. The focal point of my thesis is the extraction of climatic signals archived in stalagmites from NE India. High uranium concentration in the stalagmites ensured excellent age control required for successful high-resolution climate reconstructions. Stable isotope (d18O and d13C) and grey-scale data allow unprecedented insights into millennial to seasonal dynamics of the summer and winter monsoon in NE India. ISM strength (i. e. rainfall amount) is recorded in changes in d18Ostalagmites. The d13C signal, reflecting drip rate changes, renders a powerful proxy for dry season conditions, and shows similarities to temperature-related changes on the Tibetan Plateau. A sub-annual grey-scale profile supports a concept of lower drip rate and slower stalagmite growth during dry conditions. During the Holocene, ISM followed a millennial-scale decrease of insolation, with decadal to centennial failures resulting from atmospheric changes. The period of maximum rainfall and enhanced seasonality corresponds to the Holocene Thermal Optimum observed in Europe. After a phase of rather stable conditions, 4.5 kyr ago, the strengthening ENSO system dominated the ISM. Strong El Nino events weakened the ISM, especially when in concert with positive Indian Ocean dipole events. The strongest droughts of the last 11 kyr are recorded during the past 2 kyr. Using the advantage of a well-dated stalagmite record at hand I tested the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to detect sub-annual to sub-decadal changes in element concentrations in stalagmites. The development of a large ablation cell allows for ablating sample slabs of up to 22 cm total length. Each analyzed element is a potential proxy for different climatic parameters. Combining my previous results with the LAICP- MS-generated data shows that element concentration depends not only on rainfall amount and associated leaching from the soil. Additional factors, like biological activity and hydrogeochemical conditions in the soil and vadose zone can eventually affect the element content in drip water and in stalagmites. I present a theoretical conceptual model for my study site to explain how climatic signals can be transmitted and archived in stalagmite carbonate. Further, I establish a first 1500 year long element record, reconstructing rainfall variability. Additionally, I hypothesize that volcanic eruptions, producing large amounts of sulfuric acid, can influence soil acidity and hence element mobilization. N2 - Stalagmiten erfuhren in den letzten Jahren vermehrt Aufmerksamkeit als bedeutende Paläoklima- Archive. Paläoklimatologen sind beeindruckt von der grossen Zahl geochemischer und physikalischer Indikatoren (Proxies) und der Möglichkeit, präzise absolute Altersmodelle zu erstellen. Doch obwohl substantielle Fortschritte in der speleothem-basierten Klimaforschung gemacht wurden, und trotz hochaufgelöster Archive aus niederen Breiten, welche zeigen, das Umweltveränderungen auf Zeitskalen von Jahren bis Jahrtausenden archiviert und rekonstruiert werden können, bleibt unser Verständnis der Klimadynamik fragmentarisch. Ganz besonders gilt dies für den Indischen Sommermonsun (ISM) auf dem Indischen Subkontinent. Der ISM ist heute als ein integraler Bestandteil der intertropischen Konvergenzzone verstanden. Sobald dieser Regengürtel während des borealen Sommer nordwärts migriert kann der ISM seine feuchten Luftmassen auf dem Asiatischen Festland entladen. Dabei hängt die Stärke des ISM von einer Vielzahl von Faktoren ab. Zu diesen gehören die Schneedicke in Zentralasien im vorhergehenden Winter und ozeanische Bedingungen im Indischen und Pazifschen Ozean. Heute sind viele dieser Faktoren bekannt. Trotzdem bleiben deren Mechanismen und internen Verbindungen weiterhin mysteriös. Versuche, korrekte Vorhersagen zu Niederschlagsintensität und Häufigkeit oder zu Dürreereignissen zu erstellen ähneln einem Puzzle. All die verschiedenen Interaktionen müssen an die richtige Stelle gelegt werden, um ein sinnvolles Bild entstehen zu lassen. Meine Dissertation versucht, ein vertrauenswürdiges Bild des sich wandelnden Holozänen Klimas in Indien zu erstellen. NE Indien ist eine Schlüsselregion für den östlichen Arm des ISM, da sich hier der ISM in zwei Arme aufteilt, einen nordwestwärts und einen nordostwärts gerichteten. Das Meghalaya Plateau ist das erste Hindernis für die sich nordwärts bewegenden Luftmassen und erhält entsprechend exzessive Niederschläge während des Sommers. Die winterliche Jahreszeit dagegen ist sehr trocken. Die Nähe zum Tibetplateau einerseits und der Bucht von Bengalen andererseits determinieren die Schlüsselposition dieser Region für das Studium der Interaktionen der den ISM beeinflussenden Kräfte. Ein Fundament für die Interpretation der Paläoklimarecords und ein erstes wichtiges Ergebnis meiner Arbeit ist ein konzeptuelles Modell, welches die beobachteten saisonalen Veränderungen stabiler Isotope (d18O und d2H) im Niederschlag erklärt. Ich zeige, das obwohl in tropischen und subtropischen Regionen meist der amount effect zur Erklärung stark negativer Isotopenwerte während starker Niederschläge herangezogen wird, dieser allein nicht ausreicht, um die Isotopenvariabilität im Niederschlag Meghalaya's zu erklären. Die Langzeitbeobachtung der Regenwasserisotopie zeigt keine negative Korrelation zwischen Niederschlagsmenge und d18O. Es finden sich Hinweise, das der Abfluss aus den Hochgebirgsregionen Tibets und des Himalaya eine Isotopensignatur an das Oberflächenwasser der Bucht von Bengalen vererbt. Dort bildet sich aus isotopisch stark abgereicherten Wässern während des ISM eine Süsswasserlinse aus. Es ist wahrscheinlich, das Wasserdampf, der aus dieser Linse stammt, ein Isotopensignal aufgeprägt bekommt, welches abgereichertes d18O weitertransportiert. Der Mangel an Daten lässt es bisher leider nicht zu, quantitative Aussagen über den Einfluss dieses plume effect' auf Niederschläge in Meghalaya zu treffen. Es lässt sich allerdings vermuten, das dieser Einfluss auf saisonalen wie auch auf langen Zeitskalen variabel ist, abhängig vom Abfluss und der Quellencharacteristik. Der Fokus meiner Arbeit liegt in der Herauslösung klimatischer Signale aus nordostindischen Stalagmiten. Hohe Urankonzentrationen in diesen Stalagmiten erlaubt eine exzellente Alterskontrolle, die für hochauflösende Klimarekonstruktionen unerlässlich ist. Die stabilen Isotope (d18O und d13C), sowie Grauwertdaten, erlauben einmalige Einblicke in die Dynamik des Sommer und auch des Wintermonsun in NE Indien. Die ISM Stärke (d. h. Niederschlagsmenge) wird in Veränderungen in den d18Ostalagmites reflektiert. Das d13C Signal, welches Tropfratenänderungen speichert, dient als potenter Indikator für winterliche Trockenheitsbedingungen. Es zeigt Ähnlichkeit zu temperaturabhängigen Veränderungen auf dem Tibetplateau. Das sub-annuell aufgelöste Grauwertprofil stärkt das Konzept, das verminderte Tropfraten und langsameres Stalagmitenwachstum eine Folge von Trockenheit sind. Während des Holozäns folgte der ISM der jahrtausendelangen Verringerung der Insolation. Es finden sich aber ebenso rapide Anomalien, die aus atmosphärischen Veränderungen resultieren. Die Phase des höchsten Niederschlages und erhöhter Saisonalität korrespondiert mit dem Holozänen Thermalen Maximum. Nach einer Phase einigermassen stabilen Bedingungen begann vor ca. 4500 Jahren ENSO einen zunehmenden Einfluss auf den ISM auszuüben. Starke El Nino Ereignisse schwächen den ISM, besonders wenn diese zeitgleich mit positiven Indian Ocean Dipole Ereignissen auftreten. Die stärksten Dürren des gesamten Holozäns traten in den letzten 2000 Jahren auf. Um zusätzliche Informationen aus den hervorragenden Proben zu gewinnen nutzte ich die Vorteile der laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Diese erlaubt die Detektion sub-annueller bis sub-dekadischer Elementkonzentrationsveränderungen in Stalagmiten. Mittels einer neu entwickelten Ablationszelle konnten Proben von maximal 22 cm Länge untersucht werden. Jedes analysierte Element ist ein potentieller Träger einer Klimainformation. Die Kombination der früheren Ergebnisse mit denen der LA-IPC-MS zeigt, das die Elementkonzentrationen nicht nur von Niederschlagsveränderungen und assoziiertem Auswaschen aus dem Boden abhängen. Zusätzlich können auch die biologische Aktivität und hydrogeochemische Bedingungen in der vadosen Zone Einfluss auf die Elementzusammensetzung im Tropfwasser und in den Stalagmiten haben. Darum entwickelte ich ein theoretisches Modell für meinen Standort, um zu klären, wie Klimasignale von der Atmosphäre in die Höhle transportiert werden können. Ein anschliessend rekonstruierter 1500 Jahre langer Proxyrecord zeigt Niederschlagsvariabilität an. Zudem besteht die Möglichkeit, das Vulkaneruptionen, welche grosse Mengen an Schwefelsäure produzieren, eine Bodenversauerung verursachen und damit die Elementmobilisierung verstärken können. KW - Indischer Sommermonsun KW - Stabile Isotope KW - Stalagmiten KW - Holozän KW - Bucht von Bengalen KW - Indian Summer Monsoon KW - Bay of Bengal KW - stable isotopes KW - stalagmites KW - Laser ablation Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-37807 ER - TY - THES A1 - Kruse, Marlen T1 - Characterization of biomolecules and their interactions using electrically controllable DNA nanolevers N2 - In this work, binding interactions between biomolecules were analyzed by a technique that is based on electrically controllable DNA nanolevers. The technique was applied to virus-receptor interactions for the first time. As receptors, primarily peptides on DNA nanostructures and antibodies were utilized. The DNA nanostructures were integrated into the measurement technique and enabled the presentation of the peptides in a controllable geometrical order. The number of peptides could be varied to be compatible to the binding sites of the viral surface proteins. Influenza A virus served as a model system, on which the general measurability was demonstrated. Variations of the receptor peptide, the surface ligand density, the measurement temperature and the virus subtypes showed the sensitivity and applicability of the technology. Additionally, the immobilization of virus particles enabled the measurement of differences in oligovalent binding of DNA-peptide nanostructures to the viral proteins in their native environment. When the coronavirus pandemic broke out in 2020, work on binding interactions of a peptide from the hACE2 receptor and the spike protein of the SARS-CoV-2 virus revealed that oligovalent binding can be quantified in the switchSENSE technology. It could also be shown that small changes in the amino acid sequence of the spike protein resulted in complete loss of binding. Interactions of the peptide and inactivated virus material as well as pseudo virus particles could be measured. Additionally, the switchSENSE technology was utilized to rank six antibodies for their binding affinity towards the nucleocapsid protein of SARS-CoV-2 for the development of a rapid antigen test device. The technique was furthermore employed to show binding of a non-enveloped virus (adenovirus) and a virus-like particle (norovirus-like particle) to antibodies. Apart from binding interactions, the use of DNA origami levers with a length of around 50 nm enabled the switching of virus material. This proved that the technology is also able to size objects with a hydrodynamic diameter larger than 14 nm. A theoretical work on diffusion and reaction-limited binding interactions revealed that the technique and the chosen parameters enable the determination of binding rate constants in the reaction-limited regime. Overall, the applicability of the switchSENSE technique to virus-receptor binding interactions could be demonstrated on multiple examples. While there are challenges that remain, the setup enables the determination of affinities between viruses and receptors in their native environment. Especially the possibilities regarding the quantification of oligo- and multivalent binding interactions could be presented. N2 - In dieser Arbeit wurden Bindungsinteraktionen zwischen biologischen Molekülen mit Hilfe von elektrisch kontrollierbaren DNA-Nanohebeln untersucht. Die Technologie wurde zum ersten Mal auf Virus-Rezeptor Interaktionen angewendet. Als Rezeptoren wurden überwiegend Peptide und Antikörper untersucht. Die Peptide wurden auf vierarmigen DNA-Nanohebeln angeordnet. Ihre geometrische Anordnung entsprach der Anordnung der Rezeptorbindungsstellen der Proteine auf der Virusoberfläche. An Influenza A Viren wurde die Machbarkeit der Bindungsmessung zuerst demonstriert. Dabei konnte die Anwendbarkeit und Sensitivität der Technologie durch Variation der Peptide, der Ligandendichte auf der Sensoroberfläche, der Messtemperatur und der Virussubtypen gezeigt werden. Weiterhin wurde Virusmaterial auf der Sensoroberfläche immobilisiert und anschließend wurden quantitative Bindungsmessungen mit den oligovalenten DNA-Peptid-Strukturen durchgeführt. Dieser Versuchsaufbau ermöglichte die Messung der Bindungsstärke in Abhängigkeit der Anzahl der pro DNA-Struktur gekoppelten Peptide. Im Zuge des Ausbruchs der Coronavirus-Pandemie im Jahr 2020 wurden Bindungsinteraktionsmessungen zwischen einem Peptid aus dem hACE2-Rezeptor und SARS-CoV-2 Spike Proteinen durchgeführt. Auch hier konnten oligovalente Bindungseffekte quantifiziert werden. Außerdem wurde festgestellt, dass Veränderungen an der Aminosäuresequenz des SARS-CoV-2 Proteins starke Auswirkungen auf das Bindungsverhalten hatten. Auch Interaktionen zwischen dem Peptid und sowohl inaktiviertem Virusmaterial als auch Pseudoviruspartikeln wurden gemessen. Für die Entwicklung eines Antigenschnelltests wurden die Affinitäten von sechs Antikörpern an das Nucleocapsidprotein des SARS-CoV-2 bestimmt. Weiterhin konnte gezeigt werden, dass mit der Technologie auch die Bindung von unbehüllten Viren (am Beispiel von Adenoviren) und Virus-ähnlichen Partikeln (am Beispiel von Norovirus-ähnlichen Partikeln) an Antikörper vermessen werden kann. Neben Bindungsinteraktionen, wurden auch Größenbestimmungen mit Hilfe von DNA Origamis durchgeführt. Die Hebellänge von ca. 50 nm ermöglichte die elektrische Bewegung ("switching") von Virusmaterial. Es konnte so gezeigt werden, dass die Technologie es ermöglicht, Objekte mit einem hydrodynamischen Durchmesser von mehr als 14 nm zu bewegen. In einer theoretischen Betrachtung der Experimente konnte gezeigt werden, dass der Sensoraufbau und die verwendeten Parameter die Messung von Bindungsratenkonstanten in einem Reaktions-limitierten Bereich ermöglichen. Insgesamt konnte die Arbeit an vielen Beispielen zeigen, dass die switch-SENSE Technologie für die Messung von Virus-Rezeptor Interaktionen geeignet ist. Während es weiterhin Herausforderungen gibt, so ermöglicht der Aufbau doch die Bestimmung von Affinitäten zwischen Viren und Rezeptoren. Insbesondere die Möglichkeiten zur Quantifizierung von oligo- und multivalenten Bindungsinteraktionen konnten aufgezeigt werden. T2 - Charakterisierung von Biomolekülen und deren Interaktionen mittels elektrisch kontrollierbarer DNA Nanohebel KW - biomolecule KW - binding interactions KW - switchSENSE KW - virus KW - receptor KW - Biomoleküle KW - Bindungsinteraktion KW - switchSENSE Technologie KW - Virus KW - Rezeptor Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-577384 ER - TY - GEN A1 - Elsenbeer, Helmut A1 - Lack, Andreas A1 - Cassel, Keith T1 - Chemical fingerprints of hydrological compartments and flow paths at La Cuenca, western Amazonia N2 - A forested first-order catchment in western Amazonia was monitored for 2 years to determine the chemical fingerprints of precipitation, throughfall, overland flow, pipe flow, soil water, groundwater, and streamflow. We used five tracers (hydrogen, calcium, magnesium, potassium, and silica) to distinguish “fast” flow paths mainly influenced by the biological subsystem from “slow” flow paths in the geochemical subsystem. The former comprise throughfall, overland flow, and pipe flow and are characterized by a high potassium/silica ratio; the latter are represented by soil water and groundwater, which have a low potassium/silica ratio. Soil water and groundwater differ with respect to calcium and magnesium. The groundwater-controlled streamflow chemistry is strongly modified by contributions from fast flow paths during precipitation events. The high potassium/silica ratio of these flow paths suggests that the storm flow response at La Cuenca is dominated by event water. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 047 KW - Chemistry of fresh water KW - Runoff and streamflow KW - Weathering Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16937 ER - TY - THES A1 - Brauer, Dorothée T1 - Chemo-kinematic constraints on Milky Way models from the spectroscopic surveys SEGUE & RAVE T1 - Beschränkungen von Modellen der Milchstraße auf Basis der chemisch-kinematischen Analyse von Beobachtungsdaten der spektroskopischen Himmelsdurchmusterungen SEGUE und RAVE N2 - The Milky Way is only one out of billions of galaxies in the universe. However, it is a special galaxy because it allows to explore the main mechanisms involved in its evolution and formation history by unpicking the system star-by-star. Especially, the chemical fingerprints of its stars provide clues and evidence of past events in the Galaxy’s lifetime. These information help not only to decipher the current structure and building blocks of the Milky Way, but to learn more about the general formation process of galaxies. In the past decade a multitude of stellar spectroscopic Galactic surveys have scanned millions of stars far beyond the rim of the solar neighbourhood. The obtained spectroscopic information provide unprecedented insights to the chemo-dynamics of the Milky Way. In addition analytic models and numerical simulations of the Milky Way provide necessary descriptions and predictions suited for comparison with observations in order to decode the physical properties that underlie the complex system of the Galaxy. In the thesis various approaches are taken to connect modern theoretical modelling of galaxy formation and evolution with observations from Galactic stellar surveys. With its focus on the chemo-kinematics of the Galactic disk this work aims to determine new observational constraints on the formation of the Milky Way providing also proper comparisons with two different models. These are the population synthesis model TRILEGAL based on analytical distribution functions, which aims to simulate the number and distribution of stars in the Milky Way and its different components, and a hybrid model (MCM) that combines an N-body simulation of a Milky Way like galaxy in the cosmological framework with a semi-analytic chemical evolution model for the Milky Way. The major observational data sets in use come from two surveys, namely the “Radial Velocity Experiment” (RAVE) and the “Sloan Extension for Galactic Understanding and Exploration” (SEGUE). In the first approach the chemo-kinematic properties of the thin and thick disk of the Galaxy as traced by a selection of about 20000 SEGUE G-dwarf stars are directly compared to the predictions by the MCM model. As a necessary condition for this, SEGUE's selection function and its survey volume are evaluated in detail to correct the spectroscopic observations for their survey specific selection biases. Also, based on a Bayesian method spectro-photometric distances with uncertainties below 15% are computed for the selection of SEGUE G-dwarfs that are studied up to a distance of 3 kpc from the Sun. For the second approach two synthetic versions of the SEGUE survey are generated based on the above models. The obtained synthetic stellar catalogues are then used to create mock samples best resembling the compiled sample of observed SEGUE G-dwarfs. Generally, mock samples are not only ideal to compare predictions from various models. They also allow validation of the models' quality and improvement as with this work could be especially achieved for TRILEGAL. While TRILEGAL reproduces the statistical properties of the thin and thick disk as seen in the observations, the MCM model has shown to be more suitable in reproducing many chemo-kinematic correlations as revealed by the SEGUE stars. However, evidence has been found that the MCM model may be missing a stellar component with the properties of the thick disk that the observations clearly show. While the SEGUE stars do indicate a thin-thick dichotomy of the stellar Galactic disk in agreement with other spectroscopic stellar studies, no sign for a distinct metal-poor disk is seen in the MCM model. Usually stellar spectroscopic surveys are limited to a certain volume around the Sun covering different regions of the Galaxy’s disk. This often prevents to obtain a global view on the chemo-dynamics of the Galactic disk. Hence, a suitable combination of stellar samples from independent surveys is not only useful for the verification of results but it also helps to complete the picture of the Milky Way. Therefore, the thesis closes with a comparison of the SEGUE G-dwarfs and a sample of RAVE giants. The comparison reveals that the chemo-kinematic relations agree in disk regions where the samples of both surveys show a similar number of stars. For those parts of the survey volumes where one of the surveys lacks statistics they beautifully complement each other. This demonstrates that the comparison of theoretical models on the one side, and the combined observational data gathered by multiple surveys on the other side, are key ingredients to understand and disentangle the structure and formation history of the Milky Way. N2 - Die Milchstraße ist nur eine unter Milliarden von Galaxien im Universum, dennoch ist sie besonders. Sie bietet die einzigartige Möglichkeit anhand ihrer einzeln auflösbaren Sterne und deren im Detail beobachtbaren Eigenschaften die Mechanismen ihrer Evolutions- und Entstehungsgeschichte genau zu studieren und damit Rückschlüsse auf die Entwicklungsprozesse von Galaxien im Allgemeinen zu ziehen. Insbesondere der chemische Fingerabdruck ihrer Sterne liefert dabei Indizien und Beweise für Ereignisse im Leben der Galaxie. In den letzten 15 Jahren wurden daher in einer Vielzahl von Himmeldurchmusterungen Millionen von Sternen in der Milchstraße spektroskopisch beobachtet. Die so gewonnenen Informationen bieten detaillierte Einblicke in die Substrukturen unserer Galaxie und deren chemisch-kinematische Struktur. Ergänzend dazu liefern analytische Modelle und numerische Simulationen der Milchstraße wichtige Beschreibungen, die sich zum Vergleich mit Beobachtungen eignen, um die dem komplexen System der Galaxie zugrunde liegenden exakten physikalischen Eigenschaften entschlüsseln zu können. Die vorliegende Arbeit nutzt verschiedene Ansätze, um moderne theoretische Modelle der Galaxienentstehung und -evolution mit Daten aus stellaren Beobachtungskampagnen zu vergleichen. Die dazu analysierten Beobachtungsdatensätze stammen aus zwei großen Himmelsdurchmusterungen, dem „Radial Velocity Experiment“ (RAVE) und dem „Sloan Extension for Galactic Understanding and Exploration“ (SEGUE). Mit dem Fokus auf der chemisch-kinematischen Struktur der galaktischen Scheibe geht es im Wesentlichen darum, zwei Modelle der Milchstraße zu testen, nämlich ein Populationssynthesemodell (TRILEGAL) und ein Hybridmodell (MCM). Während TRILEGAL auf analytischen Verteilungsfunktionen basiert und zum Ziel hat, die Anzahl und Verteilung der Sterne innerhalb der Galaxie und ihrer unterschiedlichen Komponenten zu simulieren, verbindet das MCM Modell eine kosmologische N-Körper Simulation einer der Milchstraße ähnlichen Galaxie mit einem semi-analytischen Modell zur Beschreibung der chemischen Evolution der Milchstraße. Auf Grundlage einer Auswahl von etwa 20000 SEGUE G-Zwergsternen werden in einem ersten Ansatz die aus den Messdaten gewonnenen chemisch-kinematischen Eigenschaften der dünnen und dicken Scheibe der Milchstraße mit den direkten Vorhersagen des MCM Modells verglichen. Eine notwendige Bedingung dafür ist die Korrektur der Beobachtungsdaten für systematische Fehler bei der Objektauswahl der Beobachtungskampagne. Zudem werden mittels einer Bayesischen Methode spektro-photometrische Distanzen mit Fehlern kleiner als 15% für die Auswahl an SEGUE Sternen berechnet, die sich in einer Entfernung von bis zu 3 kpc von der Sonne befinden. Für den zweiten Ansatz werden basierend auf den oben genannten Modellen zwei synthetische Versionen der SEGUE Himmelsdurchmusterung generiert. Diese künstlichen stellaren Kataloge werden dann verwendet, um Vergleichspseudodatensätze für die verwendeten Zwergsterndaten anzufertigen. Solche synthetischen Testdatensätze eignen sich nicht nur, um die Vorhersagen verschiedener Modelle zu vergleichen, sie können auch zur Validierung der Qualität einzelner Modelle herangezogen werden. Während sich in der Analyse zeigt, dass TRILEGAL sich besonders gut eignet, statistische Eigenschaften der dünnen und dicken galaktischen Scheibe zu reproduzieren, spiegelt das MCM Modell viele der in der Milchstraße beobachtbaren chemisch-kinematischen Korrelationen gut wieder. Trotzdem finden sich Beweise dafür, dass dem MCM Modell eine stellare Komponente fehlt, deren Eigenschaften der in den Beobachtungen sichtbaren dicken Scheibe ähnlich sind. Meist sind spektroskopische Beobachtungskampagnen auf ein bestimmtes Volumen um die Sonne beschränkt. Oftmals verhindert dies die Möglichkeit einen globalen Blick auf die chemisch-kinematischen Eigenschaften der galaktischen Scheibe zu erlangen. Die Kombination von stellaren Daten unabhängiger Kampagnen ist daher nicht nur nützlich für die Verifikation von Ergebnissen, es hilft auch ein ganzheitlicheres Bild der Galaxie zu erlangen. Die vorliegende Arbeit schließt daher mit einem Vergleich der SEGUE G-Zwergsterne und einer Auswahl von RAVE Riesensternen. Es zeigt sich eine gute Übereinstimmung bzgl. der chemisch-kinematischen Struktur der galaktischen Scheibe besonders in denjenigen Regionen, die von einer Vielzahl von SEGUE und RAVE Objekten abgedeckt werden. Für Regionen des Beobachtungsvolumens, in dem die eine oder die andere der beiden Beobachtungskampagnen eine geringere Statistik von beobachteten Sternen aufweist, ergänzen sich RAVE und SEGUE gut. Dies zeigt, dass nicht nur der Vergleich von Beobachtungen und theoretischen Modellen, sondern auch die Kombination von Messdaten aus verschiedenen Himmelsdurchmusterungen wichtig ist, um die Struktur und die Entstehungsgeschichte der Milchstraße zu verstehen und zu entschlüsseln. KW - galaktische Astronomie KW - galactic astronomy KW - Entstehung der Milchstraße KW - Milky Way formation KW - Evolution der Milchstraße KW - Milky Way evolution KW - Milky Way chemo-kinematics KW - Chemokinematik der Milchstraße KW - SEGUE survey KW - SEGUE Beobachtungskampagne KW - RAVE survey KW - RAVE Beobachtungskampagne KW - mock data catalogues KW - Pseudodatensätze Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-403968 ER - TY - THES A1 - Bierbaum, Veronika T1 - Chemomechanical coupling and motor cycles of the molecular motor myosin V T1 - Chemomechanische Kopplung und Motorzyklen für den molekularen Motor Myosin V N2 - In the living cell, the organization of the complex internal structure relies to a large extent on molecular motors. Molecular motors are proteins that are able to convert chemical energy from the hydrolysis of adenosine triphosphate (ATP) into mechanical work. Being about 10 to 100 nanometers in size, the molecules act on a length scale, for which thermal collisions have a considerable impact onto their motion. In this way, they constitute paradigmatic examples of thermodynamic machines out of equilibrium. This study develops a theoretical description for the energy conversion by the molecular motor myosin V, using many different aspects of theoretical physics. Myosin V has been studied extensively in both bulk and single molecule experiments. Its stepping velocity has been characterized as a function of external control parameters such as nucleotide concentration and applied forces. In addition, numerous kinetic rates involved in the enzymatic reaction of the molecule have been determined. For forces that exceed the stall force of the motor, myosin V exhibits a 'ratcheting' behaviour: For loads in the direction of forward stepping, the velocity depends on the concentration of ATP, while for backward loads there is no such influence. Based on the chemical states of the motor, we construct a general network theory that incorporates experimental observations about the stepping behaviour of myosin V. The motor's motion is captured through the network description supplemented by a Markov process to describe the motor dynamics. This approach has the advantage of directly addressing the chemical kinetics of the molecule, and treating the mechanical and chemical processes on equal grounds. We utilize constraints arising from nonequilibrium thermodynamics to determine motor parameters and demonstrate that the motor behaviour is governed by several chemomechanical motor cycles. In addition, we investigate the functional dependence of stepping rates on force by deducing the motor's response to external loads via an appropriate Fokker-Planck equation. For substall forces, the dominant pathway of the motor network is profoundly different from the one for superstall forces, which leads to a stepping behaviour that is in agreement with the experimental observations. The extension of our analysis to Markov processes with absorbing boundaries allows for the calculation of the motor's dwell time distributions. These reveal aspects of the coordination of the motor's heads and contain direct information about the backsteps of the motor. Our theory provides a unified description for the myosin V motor as studied in single motor experiments. N2 - Die hier vorgelegte Arbeit entwickelt unter Verwendung vieler verschiedener Aspekte der statistischen Physik eine Theorie der chemomechanischen Kopplung für den Energieumsatz des molekularen Motors Myosin V. Das Myosin V ist sowohl in chemokinetischen wie in Einzelmolekülexperimenten grundlegend untersucht worden. Seine Schrittgeschwindigkeit ist in Abhängigkeit verschiedener externer Parameter, wie der Nukleotidkonzentration und einer äußeren Kraft, experimentell bestimmt. Darüber hinaus ist eine große Anzahl verschiedener chemokinetischer Raten, die an der enzymatischen Reaktion des Moleküls beteiligt sind, quantitativ erfasst. Unter der Wirkung externer Kräfte, die seine Anhaltekraft überschreiten, verhält sich der Motor wie eine Ratsche: Für Kräfte, die entlang der Schrittbewegung des Motors wirken, hängt seine Geschwindigkeit von der ATP-Konzentration ab, für rückwärts angreifende Kräfte jedoch ist die Bewegung des Motors unabhängig von ATP. Auf der Grundlage der chemischen Zustände des Motors wird eine Netzwerktheorie aufgebaut, die die experimentellen Beobachtungen des Schrittverhaltens für Myosin V einschließt. Diese Netzwerkbeschreibung dient als Grundlage für einen Markovprozess, der die Dynamik des Motors beschreibt. Die Verwendung diskreter Zustände bietet den Vorteil der direkten Erfassung der chemischen Kinetik des Moleküls. Darüber hinaus werden chemische und mechanische Eigenschaften des Motors in gleichem Maße im Modell berücksichtigt. Durch die Erfassung der Enzymkinetik mittels eines stochastischen Prozesses lässt sich die Motordynamik mit Hilfe des stationären Zustands der Netzwerkdarstellung beschreiben. Um diesen zu bestimmen, verwenden wir eine graphentheoretische Methode, die auf Kirchhoff zurückgreift. Wir zeigen in Einklang mit den Gesetzen der Thermodynamik für Nichtgleichgewichtssysteme, dass das Schrittverhalten des Motors von mehreren chemomechanischen Zyklen beeinflusst wird. Weiterhin untersuchen wir das funktionale Verhalten mechanischer Schrittraten in Abhängigkeit der äußeren Kraft unter Verwendung einer geeigneten Fokker-Planck-Gleichung. Hierfür wird auf die Theorie einer kontinuierlichen Beschreibung von molekularen Methoden zurückgegriffen. Wir berechnen Größen wie die mittlere Schrittgeschwindigkeit, das Verhältnis von Vorwärts- und Rückwärtsschritten, und die Lauflänge des Motors in Abhängigkeit einer äußeren angreifenden Kraft sowie der Nukleotidkonzentration, und vergleichen diese mit experimentellen Daten. Für Kräfte, die kleiner als die Anhaltekraft des Motors sind, unterscheidet sich der chemomechanische Zyklus grundlegend von demjenigen, der für große Kräfte dominiert. Diese Eigenschaft resultiert in einem Schrittverhalten, das mit den experimentellen Beobachtungen übereinstimmt. Es ermöglicht weiterhin die Zerlegung des Netzwerks in einzelne Zyklen, die die Bewegung des Motors für verschiedene Bereiche externer Kräfte erfassen. Durch die Erweiterung unseres Modells auf Markovprozesse mit absorbierenden Zuständen können so die Wartezeitenverteilungen für einzelne Zyklen des Motors analytisch berechnet werden. Sie erteilen Aufschluss über die Koordination des Motors und enthalten zudem direkte Informationen über seine Rückwärtsschritte, die experimentell nicht erfasst sind. Für das gesamte Netzwerk werden die Wartezeitenverteilungen mit Hilfe eines Gillespie-Algorithmus bestimmt. Unsere Theorie liefert eine einheitliche Beschreibung der Eigenschaften von Myosin V, die in Einzelmolekülexperimenten erfasst werden können. KW - statistische Physik KW - Markov-Prozesse KW - molekulare Motoren KW - statistical physics KW - markov processes KW - molecular motors Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-53614 ER - TY - JOUR A1 - Lindner, Nadja A1 - Moeller, Korbinian A1 - Hildebrandt, Frauke A1 - Hasselhorn, Marcus A1 - Lonnemann, Jan T1 - Children's use of egocentric reference frames in spatial language is related to their numerical magnitude understanding JF - Frontiers in Psychology N2 - Numerical magnitude information is assumed to be spatially represented in the form of a mental number line defined with respect to a body-centred, egocentric frame of reference. In this context, spatial language skills such as mastery of verbal descriptions of spatial position (e.g., in front of, behind, to the right/left) have been proposed to be relevant for grasping spatial relations between numerical magnitudes on the mental number line. We examined 4- to 5-year-old’s spatial language skills in tasks that allow responses in egocentric and allocentric frames of reference, as well as their relative understanding of numerical magnitude (assessed by a number word comparison task). In addition, we evaluated influences of children’s absolute understanding of numerical magnitude assessed by their number word comprehension (montring different numbers using their fingers) and of their knowledge on numerical sequences (determining predecessors and successors as well as identifying missing dice patterns of a series). Results indicated that when considering responses that corresponded to the egocentric perspective, children’s spatial language was associated significantly with their relative numerical magnitude understanding, even after controlling for covariates, such as children’s SES, mental rotation skills, and also absolute magnitude understanding or knowledge on numerical sequences. This suggests that the use of egocentric reference frames in spatial language may facilitate spatial representation of numbers along a mental number line and thus seem important for preschoolers’ relative understanding of numerical magnitude. KW - spatial language KW - frames of reference KW - numerical development KW - mental number line KW - preschool children Y1 - 2022 U6 - https://doi.org/10.3389/fpsyg.2022.943191 SN - 1664-1078 SP - 1 EP - 13 PB - Frontiers CY - Lausanne, Schweiz ER - TY - JOUR A1 - Marimon Tarter, Mireia A1 - Hofmann, Andrea A1 - Veríssimo, Joao Marques A1 - Männel, Claudia A1 - Friederici, Angela Dorkas A1 - Höhle, Barbara A1 - Wartenburger, Isabell T1 - Children’s Learning of Non-adjacent Dependencies Using a Web-Based Computer Game Setting JF - Frontiers in Psychology N2 - Infants show impressive speech decoding abilities and detect acoustic regularities that highlight the syntactic relations of a language, often coded via non-adjacent dependencies (NADs, e.g., is singing). It has been claimed that infants learn NADs implicitly and associatively through passive listening and that there is a shift from effortless associative learning to a more controlled learning of NADs after the age of 2 years, potentially driven by the maturation of the prefrontal cortex. To investigate if older children are able to learn NADs, Lammertink et al. (2019) recently developed a word-monitoring serial reaction time (SRT) task and could show that 6–11-year-old children learned the NADs, as their reaction times (RTs) increased then they were presented with violated NADs. In the current study we adapted their experimental paradigm and tested NAD learning in a younger group of 52 children between the age of 4–8 years in a remote, web-based, game-like setting (whack-a-mole). Children were exposed to Italian phrases containing NADs and had to monitor the occurrence of a target syllable, which was the second element of the NAD. After exposure, children did a “Stem Completion” task in which they were presented with the first element of the NAD and had to choose the second element of the NAD to complete the stimuli. Our findings show that, despite large variability in the data, children aged 4–8 years are sensitive to NADs; they show the expected differences in r RTs in the SRT task and could transfer the NAD-rule in the Stem Completion task. We discuss these results with respect to the development of NAD dependency learning in childhood and the practical impact and limitations of collecting these data in a web-based setting. KW - non-adjacent dependencies KW - rule learning KW - web-based KW - implicit learning KW - serial reaction time (SRT) task KW - SRT Y1 - 2021 U6 - https://doi.org/10.3389/fpsyg.2021.734877 SN - 1664-1078 VL - 12 SP - 1 EP - 15 PB - Frontiers CY - Lausanne, Schweiz ER - TY - THES A1 - Oey, Melanie T1 - Chloroplasts as bioreactors : high-yield production of active bacteriolytic protein antibiotics T1 - Chloroplasten als Bioreaktoren : hocheffiziente Produktion von aktiven, bakteriolytischen Proteinantibiotika N2 - Plants, more precisely their chloroplasts with their bacterial-like expression machinery inherited from their cyanobacterial ancestors, can potentially offer a cheap expression system for proteinaceous pharmaceuticals. This system would be easily scalable and provides appropriate safety due to chloroplasts maternal inheritance. In this work, it was shown that three phage lytic enzymes (Pal, Cpl-1 and PlyGBS) could be successfully expressed at very high levels and with high stability in tobacco chloroplasts. PlyGBS expression reached an amount of foreign protein accumulation (> 70% TSP) that has never been obtained before. Although the high expression levels of PlyGBS caused a pale green phenotype with retarded growth, presumably due to exhaustion of plastid protein synthesis capacity, development and seed production were not impaired under greenhouse conditions. Since Pal and Cpl-1 showed toxic effects when expressed in E. coli, a special plastid transformation vector (pTox) was constructed to allow DNA amplification in bacteria. The construction of the pTox transformation vector allowing a recombinase-mediated deletion of an E. coli transcription block in the chloroplast, leading to an increase of foreign protein accumulation to up to 40% of TSP for Pal and 20% of TSP for Cpl-1. High dose-dependent bactericidal efficiency was shown for all three plant-derived lytic enzymes using their pathogenic target bacteria S. pyogenes and S. pneumoniae. Confirmation of specificity was obtained for the endotoxic proteins Pal and Cpl-1 by application to E. coli cultures. These results establish tobacco chloroplasts as a new cost-efficient and convenient production platform for phage lytic enzymes and address the greatest obstacle for clinical application. The present study is the first report of lysin production in a non-bacterial system. The properties of chloroplast-produced lysins described in this work, their stability, high accumulation rate and biological activity make them highly attractive candidates for future antibiotics. N2 - Lytische Enzyme aus Bakteriophagen bieten Eigenschaften, die sie zu vielversprechenden Medikamenten im Einsatz gegen bakterielle Krankheiten machen. Obwohl sie speziell beim Einsatz gegen bakterielle Infektionen, welche durch Antibiotika resistente Erreger hervorgerufen werden, eine maßgebende Rolle spielen könnten, waren bisher die hohen Produktionskosten ein Hindernis für die medizinische Anwendung. Ein kostengünstiges und einfach zu handhabendes System, wie beispielsweise Chloroplasten in Pflanzen, würde diese lytischen Enzyme zu einer effizienten Alternative zu herkömmlichen Antibiotika machen. In dieser Arbeit wird erstmals die erfolgreiche Produktion von lytischen Enzymen in Tabak-Chloroplasten vorgestellt, welche mit einem Fremdproteingehalt von mehr als 70% des gesamtlöslichen Proteins der Pflanze eine Menge beschreibt, die bisher mit diesem Verfahren noch nicht erreicht wurde. Alle in Chloroplasten hergestellten lytischen Enzyme zeigten hohe spezifische bakteriolytische Aktivität gegen die gewählten Humanpathogene und waren innerhalb von Minuten in der Lage diese Bakterien abzutöten. Zur Herstellung von zwei lytischen Enzymen wurde in dieser Arbeit ein spezieller Shuttle-Vektor entworfen, der die Expression von toxischen Genen innerhalb von E. coli Zellen im Zuge der DNA Replikation vermeidet, jedoch die Herstellung einer ungehinderten Expression der toxischen Gene in den Chloroplasten nach Beseitigung des Selektionsmarkers erlaubte. Ein Vergleich zwischen einem herkömmlich verwendeten Transformationsvektor und dem Shuttle-Vektor mittels eines Reportergens zeigte, dass das neu entwickelte System bis zu 4 mal mehr Protein produzierte. Diese Ergebnisse zeigen das Potential von Chloroplasten als kostengünstige und leicht zu handhabende Produktionsplattform für lytische Enzyme, welche als neue Generation von Antibiotika attraktive Alternativen zu herkömmlichen Therapien bieten. KW - Phagenlysine KW - Chloroplastentransformation KW - Antibiotikaersatz KW - Antibiotikaresistenz KW - Phage lysins KW - Chloroplast transformation KW - Antibiotic alternatives KW - Antibiotic resistance Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-28950 ER - TY - CHAP A1 - Ignace, R. A1 - Gayley, K. G. T1 - Circumstellar Magnetic Field Diagnostics from Line Polarization Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18066 ER - TY - CHAP A1 - Mills, Gregory J. A1 - Healey, Patrick G. T. T1 - Clarifying spatial descriptions : local and global effects on semantic co-ordination N2 - A key problem for models of dialogue is to explain the mechanisms involved in generating and responding to clarification requests. We report a 'Maze task' experiment that investigates the effect of 'spoof' clarification requests on the development of semantic co-ordination. The results provide evidence of both local and global semantic co-ordination phenomena that are not captured by existing dialogue co-ordination models. Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10414 ER - TY - THES A1 - Holsten, Anne T1 - Climate change vulnerability assessments in the regional context T1 - Studien zur Vulnerabilität gegenüber Klimawandel im regionalen Kontext N2 - Adapting sectors to new conditions under climate change requires an understanding of regional vulnerabilities. Conceptually, vulnerability is defined as a function of sensitivity and exposure, which determine climate impacts, and adaptive capacity of a system. Vulnerability assessments for quantifying these components have become a key tool within the climate change field. However, there is a disagreement on how to make the concept operational in studies from a scientific perspective. This conflict leads to many still unsolved challenges, especially regarding the quantification and aggregation of the components and their suitable level of complexity. This thesis therefore aims at advancing the scientific foundation of such studies by translating the concept of vulnerability into a systematic assessment structure. This includes all components and implies that for each considered impact (e.g. flash floods) a clear sensitive entity is defined (e.g. settlements) and related to a direction of change for a specific climatic stimulus (e.g. increasing impact due to increasing days with heavy precipitation). Regarding the challenging aggregation procedure, two alternative methods allowing a cross-sectoral overview are introduced and their advantages and disadvantages discussed. This assessment structure is subsequently exemplified for municipalities of the German state North Rhine-Westphalia via an indicator-based deductive approach using information from literature. It can be transferred also to other regions. As for many relevant sectors, suitable indicators to express the vulnerability components are lacking, new quantification methods are developed and applied in this thesis, for example for the forestry and health sector. A lack of empirical data on relevant thresholds is evident, for example which climatic changes would cause significant impacts. Consequently, the multi-sectoral study could only provide relative measures for each municipality, in relation to the region. To fill this gap, an exemplary sectoral study was carried out on windthrow impacts in forests to provide an absolute quantification of the present and future impact. This is achieved by formulating an empirical relation between the forest characteristics and damage based on data from a past storm event. The resulting measure indicating the sensitivity is then combined with wind conditions. Multi-sectoral vulnerability assessments require considerable resources, which often hinders the implementation. Thus, in a next step, the potential for reducing the complexity is explored. To predict forest fire occurrence, numerous meteorological indices are available, spanning over a range of complexity. Comparing their performance, the single variable relative humidity outperforms complex indicators for most German states in explaining the monthly fire pattern. This is the case albeit it is itself an input factor in most indices. Thus, this meteorological factor alone is well suited to evaluate forest fire danger in many Germany regions and allows a resource-efficient assessment. Similarly, the complexity of methods is assessed regarding the application of the ecohydrological model SWIM to the German region of Brandenburg. The inter-annual soil moisture levels simulated by this model can only poorly be represented by simpler statistical approach using the same input data. However, on a decadal time horizon, the statistical approach shows a good performance and a strong dominance of the soil characteristic field capacity. This points to a possibility to reduce the input factors for predicting long-term averages, but the results are restricted by a lack of empirical data on soil water for validation. The presented assessments of vulnerability and its components have shown that they are still a challenging scientific undertaking. Following the applied terminology, many problems arise when implementing it for regional studies. Advances in addressing shortcomings of previous studies have been made by constructing a new systematic structure for characterizing and aggregating vulnerability components. For this, multiple approaches were presented, but they have specific advantages and disadvantages, which should also be carefully considered in future studies. There is a potential to simplify some methods, but more systematic assessments on this are needed. Overall, this thesis strengthened the use of vulnerability assessments as a tool to support adaptation by enhancing their scientific basis. N2 - Die Anpassung von Sektoren an veränderte klimatische Bedingungen erfordert ein Verständnis von regionalen Vulnerabilitäten. Vulnerabilität ist als Funktion von Sensitivität und Exposition, welche potentielle Auswirkungen des Klimawandels darstellen, und der Anpassungsfähigkeit von Systemen definiert. Vulnerabilitätsstudien, die diese Komponenten quantifizieren, sind zu einem wichtigen Werkzeug in der Klimawissenschaft geworden. Allerdings besteht von der wissenschaftlichen Perspektive aus gesehen Uneinigkeit darüber, wie diese Definition in Studien umgesetzt werden soll. Ausdiesem Konflikt ergeben sich viele Herausforderungen, vor allem bezüglich der Quantifizierung und Aggregierung der einzelnen Komponenten und deren angemessenen Komplexitätsniveaus. Die vorliegende Dissertation hat daher zum Ziel die Anwendbarkeit des Vulnerabilitätskonzepts voranzubringen, indem es in eine systematische Struktur übersetzt wird. Dies beinhaltet alle Komponenten und schlägt für jede Klimaauswirkung (z.B. Sturzfluten) eine Beschreibung des vulnerablen Systems vor (z.B. Siedlungen), welches direkt mit einer bestimmten Richtung eines relevanten klimatischen Stimulus in Verbindung gebracht wird (z.B. stärkere Auswirkungen bei Zunahme der Starkregentage). Bezüglich der herausfordernden Prozedur der Aggregierung werden zwei alternative Methoden, die einen sektorübergreifenden Überblick ermöglichen, vorgestellt und deren Vor- und Nachteile diskutiert. Anschließend wird die entwickelte Struktur einer Vulnerabilitätsstudie mittels eines indikatorbasierten und deduktiven Ansatzes beispielhaft für Gemeinden in Nordrhein-Westfalen in Deutschland angewandt. Eine Übertragbarkeit auf andere Regionen ist dennoch möglich. Die Quantifizierung für die Gemeinden stützt sich dabei auf Informationen aus der Literatur. Da für viele Sektoren keine geeigneten Indikatoren vorhanden waren, werden in dieser Arbeit neue Indikatoren entwickelt und angewandt, beispielsweise für den Forst- oder Gesundheitssektor. Allerdings stellen fehlende empirische Daten bezüglich relevanter Schwellenwerte eine Lücke dar, beispielsweise welche Stärke von Klimaänderungen eine signifikante Auswirkung hervorruft. Dies führt dazu, dass die Studie nur relative Aussagen zum Grad der Vulnerabilität jeder Gemeinde im Vergleich zum Rest des Bundeslandes machen kann. Um diese Lücke zu füllen, wird für den Forstsektor beispielhaft die heutige und zukünftige Sturmwurfgefahr von Wäldern berechnet. Zu diesem Zweck werden die Eigenschaften der Wälder mit empirischen Schadensdaten eines vergangenen Sturmereignisses in Verbindung gebracht. Der sich daraus ergebende Sensitivitätswert wird anschließend mit den Windverhältnissen verknüpft. Sektorübergreifende Vulnerabilitätsstudien erfordern beträchtliche Ressourcen, was oft deren Anwendbarkeit erschwert. In einem nächsten Schritt wird daher das Potential einer Vereinfachung der Komplexität anhand zweier sektoraler Beispiele untersucht. Um das Auftreten von Waldbränden vorherzusagen, stehen zahlreiche meteorologische Indices zur Verfügung, welche eine Spannbreite unterschiedlicher Komplexitäten aufweisen. Bezüglich der Anzahl monatlicher Waldbrände weist die relative Luftfeuchtigkeit für die meisten deutschen Bundesländer eine bessere Vorhersagekraft als komplexere Indices auf. Dies ist er Fall, obgleich sie selbst als Eingangsvariable für die komplexeren Indices verwendet wird. Mit Hilfe dieses einzelnen meteorologischen Faktors kann also die Waldbrandgefahr in deutschen Region ausreichend genau ausgedrückt werden, was die Ressourceneffizienz von Studien erhöht. Die Methodenkomplexität wird auf ähnliche Weise hinsichtlich der Anwendung des ökohydrologischen Modells SWIM für die Region Brandenburg untersucht. Die interannuellen Bodenwasserwerte, welche durch dieses Modell simuliert werden, können nur unzureichend durch ein einfacheres statistisches Modell, welches auf denselben Eingangsdaten aufbaut, abgebildet werden. Innerhalb eines Zeithorizonts von Jahrzehnten, kann der statistische Ansatz jedoch das Bodenwasser zufriedenstellend abbilden und zeigt eine Dominanz der Bodeneigenschaft Feldkapazität. Dies deutet darauf hin, dass die Komplexität im Hinblick auf die Anzahl der Eingangsvariablen für langfristige Berechnungen reduziert werden kann. Allerdings sind die Aussagen durch fehlende beobachtete Bodenwasserwerte zur Validierung beschränkt. Die vorliegenden Studien zur Vulnerabilität und ihren Komponenten haben gezeigt, dass eine Anwendung noch immer wissenschaftlich herausfordernd ist. Folgt man der hier verwendeten Vulnerabilitätsdefinition, treten zahlreiche Probleme bei der Implementierung in regionalen Studien auf. Mit dieser Dissertation wurden Fortschritte bezüglich der aufgezeigten Lücken bisheriger Studien erzielt, indem eine systematische Struktur für die Beschreibung und Aggregierung von Vulnerabilitätskomponenten erarbeitet wurde. Hierfür wurden mehrere Ansätze diskutiert, die jedoch Vor- und Nachteile besitzen. Diese sollten vor der Anwendung von zukünftigen Studien daher ebenfalls sorgfältig abgewogen werden. Darüber hinaus hat sich gezeigt, dass ein Potential besteht einige Ansätze zu vereinfachen, jedoch sind hierfür weitere Untersuchungen nötig. Insgesamt konnte die Dissertation die Anwendung von Vulnerabilitätsstudien als Werkzeug zur Unterstützung von Anpassungsmaßnahmen stärken. KW - Klimawandel KW - Impakt KW - Vulnerabilität KW - Forstwirtschaft KW - Boden KW - climate change KW - impact KW - vulnerability KW - forestry KW - soil Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-66836 ER - TY - THES A1 - Hoffmann, Toni T1 - Cloning and characterisation of the HMA3 gene and its promoter from Arabidopsis halleri (L.) O'Kane and Al'Shehbaz and Arabidopsis thaliana (L.) Heynhold T1 - Klonierung und Charakterisierung des HMA3 Genes und seines Promotors aus Arabidopsis halleri (L.) O'Kane und Al'Shehbaz und Arabidopsis thaliana (L.) Heynhold N2 - Being living systems unable to adjust their location to changing environmental conditions, plants display homeostatic networks that have evolved to maintain transition metal levels in a very narrow concentration range in order to avoid either deficiency or toxicity. Hence, plants possess a broad repertoire of mechanisms for the cellular uptake, compartmentation and efflux, as well as for the chelation of transition metal ions. A small number of plants are hypertolerant to one or a few specific transition metals. Some metal tolerant plants are also able to hyperaccumulate metal ions. The Brassicaceae family member Arabidopis halleri ssp. halleri (L.) O´KANE and AL´SHEHBAZ is a hyperaccumulator of zinc (Zn), and it is closely related to the non-hypertolerant and non-hyperaccumulating model plant Arabidopsis thaliana (L.) HEYNHOLD. The close relationship renders A. halleri a promising emerging model plant for the comparative investigation of the molecular mechanisms behind hypertolerance and hyperaccumulation. Among several potential candidate genes that are probably involved in mediating the zinc-hypertolerant and zinc-hyperaccumulating trait is AhHMA3. The AhHMA3 gene is highly similar to AtHMA3 (AGI number: At4g30120) in A. thaliana, and its encoded protein belongs to the P-type IB ATPase family of integral membrane transporter proteins that transport transition metals. In contrast to the low AtHMA3 transcript levels in A. thaliana, the gene was found to be constitutively highly expressed across different Zn treatments in A. halleri, especially in shoots. In this study, the cloning and characterisation of the HMA3 gene and its promoter from Arabidopsis halleri (L.) O´KANE and AL´SHEHBAZ and Arabidopsis thaliana (L.) HEYNHOLD is described. Heterologously expressed AhHMA3 mediated enhanced tolerance to Zn and to a much lesser degree to cadmium (Cd) but not to cobalt (Co) in metal-sensitive mutant strains of budding yeast. It is demonstrated that the genome of A. halleri contains at least four copies of AhHMA3, AhHMA3-1 to AhHMA3-4. A copy-specific real-time RT-PCR indicated that an AhHMA3-1 related gene copy is the source of the constitutively high transcript level in A. halleri and not a gene copy similar to AhHMA3-2 or AhHMA3-4. In accordance with the enhanced AtHMA3mRNA transcript level in A. thaliana roots, an AtHMA3 promoter-GUS gene construct mediated GUS activity predominantly in the vascular tissues of roots and not in shoots. However, the observed AhHMA3-1 and AhHMA3-2 promoter-mediated GUS activity in A. thaliana or A. halleri plants did not reflect the constitutively high expression of AhHMA3 in shoots of A. halleri. It is suggested that other factors e. g. characteristic sequence inserts within the first intron of AhHMA3-1 might enable a constitutively high expression. Moreover, the unknown promoter of the AhHMA3-3 gene copy could be the source of the constitutively high AhHMA3 transcript levels in A. halleri. In that case, the AhHMA3-3 sequence is predicted to be highly homologous to AhHMA3-1. The lack of solid localisation data for the AhHMA3 protein prevents a clear functional assignment. The provided data suggest several possible functions of the AhHMA3 protein: Like AtHMA2 and AtHMA4 it might be localised to the plasma membrane and could contribute to the efficient translocation of Zn from root to shoot and/or to the cell-to-cell distribution of Zn in the shoot. If localised to the vacuolar membrane, then a role in maintaining a low cytoplasmic zinc concentration by vacuolar zinc sequestration is possible. In addition, AhHMA3 might be involved in the delivery of zinc ions to trichomes and mesophyll leaf cells that are major zinc storage sites in A. halleri. N2 - Pflanzen sind lebende Systeme, die nicht in der Lage sind ihren Standort sich ändernden Umweltbedingungen anzupassen. Infolgedessen weisen Pflanzen homöostatischeNetzwerke auf, welche die Mengen an intrazellulären Übergangsmetallen in einem sehr engen Konzentrationsbereich kontrollieren um somit Vergiftungs- oder Mangelerscheinungen zu vermeiden. Eine kleine Anzahl von Pflanzen ist hypertolerant gegenüber einem oder mehreren Übergangsmetallen. Einige wenige dieser metalltoleranten Pflanzen sind fähig Übergangsmetalle in beträchtlichen Mengen zu speichern, sprich zu hyperakkumulieren, ohne Vergiftungserscheinungen zu zeigen. Die Haller’sche Schaumkresse (Arabidopis halleri ssp. halleri (L.) O´KANE und AL´SHEHBAZ) aus der Familie der Kreuzblütler (Brassicaceae) ist ein solcher Hyperakkumulator für Zink (Zn). Sie ist nah verwandt mit der Modellpflanze Ackerschmalwand (Arabidopsis thaliana (L.) HEYNHOLD), die jedoch nicht-hypertolerant und nicht-hyperakkumulierend für Übergangsmetalle ist. Diese nahe Verwandtschaft erlaubt vergleichende Studien der molekularen Mechanismen, die Hypertoleranz und Hyperakkumulation zu Grunde liegen. Zu der Gruppe von Kandidatengenen, die möglicherweise von Bedeutung für die Zink-hypertoleranten und -hyperakkumulierenden Eigenschaften von A. halleri sind, gehört AhHMA3, ein Gen mit großer Ähnlichkeit zu AtHMA3 (AGI Nummer: At4g30120) aus A. thaliana. Es kodiert ein Protein aus der Familie transmembraner Übergangsmetall-Transportproteine, den P-typ IB ATPasen. Im Gegensatz zu den niedrigen AtHMA3 Transkriptmengen in A. thaliana wird das AhHMA3 Gen in A. halleri in Gegenwart verschiedener Zn Konzentrationen konstitutiv hoch exprimiert, insbesondere im Spross der Pflanze. Diese Arbeit beschreibt die Klonierung und Charakterisierung des HMA3 Gens und seines Promoters aus A. halleri und A. thaliana. Es wurde gezeigt, dass heterolog exprimiertes AhHMA3 Protein in metallsensitiven Hefestämmen eine erhöhte Toleranz gegenüber Zink und zu einem geringen Grad gegenüber Kadmium (Cd) jedoch nicht gegenüber Kobalt (Co) vermittelt.Weiterhin wurden im Genom von A. halleri mindestens vier AhHMA3 Genkopien, AhHMA3-1 bis AhHMA3-4, nachgewiesen. Eine Genkopie-spezifische Echtzeit-RT-PCR (real-time RT-PCR) deutete darauf hin, dass eine zu AhHMA3-1 und nicht zu AhHMA3-2 oder AhHMA3-4 ähnliche Genkopie die Quelle der konstitutiv hohen Transkriptmengen in A. halleri ist. In Übereinstimmung mit erhöhten mRNS Transkriptmengen inWurzeln von A. thaliana, vermittelte ein AtHMA3 Promoter-GUS (ß-Glucuronidase) Genkonstrukt GUS-Aktivität hauptsächlich in den Leitgeweben der Wurzeln jedoch nicht des Sprosses. Die vermittelte GUS-Aktivität durch Promoterfragmente von AhHMA3-1 und AhHMA3-2 in A. thaliana oder A. halleri Pflanzen spiegelte jedoch nicht die konstitutiv hohe AhHMA3 Expression im Spross von A. halleri wieder. Es wird vermutet, dass andere Faktoren die konstitutiv hohe Expression ermöglichen wie zum Beispiel die gefundenen kopiespezifischen Sequenzinsertionen innerhalb des ersten AhHMA3-1 Introns. Weiterhin ist es denkbar, dass der unbekannte Promoter der AhHMA3-3 Genkopie die Quelle der konstitutiv hohen AhHMA3 Transkriptmengen ist. In diesem Fall wird eine sehr hohe Ähnlichkeit zwischen den Sequenzen von AhHMA3-3 und der AhHMA3-1 vorhergesagt. Es konnten keine deutlichen Ergebnisse zur intrazellulären Lokalisierung gemacht werden, die eine exakte Einordnung der Funktion des AhHMA3 Proteins erlauben würden. Die bisher ermittelten Ergebnisse schlagen jedoch mehrere mögliche Funktionen für AhHMA3 vor: Ähnlich den AhHMA3 homologen Proteinen, AtHMA2 und AtHMA4, könnte AhHMA3 in der Plasmamembran der Zelle sitzen und dort zur effizienten Translokation von Zink aus der Wurzel in den Spross und/oder zur Zell-zu-Zell Verteilung von Zn im Spross beitragen. Falls AhHMA3 in der Membran der Vakuole sitzt, könnte es eine Rolle bei der Aufrechterhaltung niedriger zytoplasmatischer Zinkkonzentrationen durch vakuoläre Zinksequestrierung spielen. Zusätzlich ist es denkbar, dass AhHMA3 an der Abgabe von Zinkionen an Trichome und Blattmesophyllzellen beteiligt ist, die die Haupteinlagerungsorte für Zink in A. halleri darstellen. KW - P-Typ ATPase KW - Übergangsmetalle KW - Hyperakkumulation KW - Zink KW - HMA KW - p-type ATPase KW - transition metals KW - hyperaccumulation KW - zinc KW - HMA Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15259 ER - TY - CHAP A1 - Reimer, A. T1 - Clumping effects on non-thermal particle spectra in massive star systems N2 - Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18246 ER - TY - CHAP A1 - Liermann, A. A1 - Hamann, Wolf-Rainer T1 - Clumping in Galactic WN stars : a comparison of mass loss rates from UV/optical & radio diagnostics N2 - The mass loss rates and other parameters for a large sample of Galactic WN stars have been revised by Hamann et al. (2006), using the most up-to date Potsdam Wolf-Rayet (PoWR) model atmospheres. For a sub-sample of these stars exist measurements of their radio free-free emission. After harmonizing the adopted distance and terminal wind velocities, we compare the mass loss rates obtained from the two diagnostics. The differences are discussed as a possible consequence of different clumping contrast in the line-forming and radio-emitting regions. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17816 ER - TY - CHAP ED - Hamann, Wolf-Rainer ED - Feldmeier, Achim ED - Oskinova, Lida T1 - Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007 N2 - Stellar winds play an important role for the evolution of massive stars and their cosmic environment. Multiple lines of evidence, coming from spectroscopy, polarimetry, variability, stellar ejecta, and hydrodynamic modeling, suggest that stellar winds are non-stationary and inhomogeneous. This is referred to as 'wind clumping'. The urgent need to understand this phenomenon is boosted by its far-reaching implications. Most importantly, all techniques to derive empirical mass-loss rates are more or less corrupted by wind clumping. Consequently, mass-loss rates are extremely uncertain. Within their range of uncertainty, completely different scenarios for the evolution of massive stars are obtained. Settling these questions for Galactic OB, LBV and Wolf-Rayet stars is prerequisite to understanding stellar clusters and galaxies, or predicting the properties of first-generation stars. In order to develop a consistent picture and understanding of clumped stellar winds, an international workshop on 'Clumping in Hot Star Winds' was held in Potsdam, Germany, from 18. - 22. June 2007. About 60 participants, comprising almost all leading experts in the field, gathered for one week of extensive exchange and discussion. The Scientific Organizing Committee (SOC) included John Brown (Glasgow), Joseph Cassinelli (Madison), Paul Crowther (Sheffield), Alex Fullerton (Baltimore), Wolf-Rainer Hamann (Potsdam, chair), Anthony Moffat (Montreal), Stan Owocki (Newark), and Joachim Puls (Munich). These proceedings contain the invited and contributed talks presented at the workshop, and document the extensive discussions. KW - Sternwinde KW - Massenverlust KW - Strahlungstransport KW - hydrodynamische Modellierung KW - massereiche Sterne KW - stellar winds KW - mass loss KW - radiative transfer KW - hydrodynamic modeling KW - massive stars Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13981 SN - 978-3-940793-33-1 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - CHAP A1 - Puls, Joachim A1 - Markova, N. A1 - Najarro, F. A1 - Hanson, M. M. T1 - Clumping in O-star winds N2 - We review various diagnostics of clumping in O-star winds, with special emphasis on its radial stratification. Implications and problems are discussed, and promising NIR methods are presented. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17683 ER - TY - CHAP A1 - Bouret, J.-C. A1 - Lanz, T. A1 - Hillier, D. J. A1 - Foellmi, C. T1 - Clumping in O-type Supergiants N2 - We have analyzed the spectra of seven Galactic O4 supergiants, with the NLTE wind code CMFGEN. For all stars, we have found that clumped wind models match well lines from different species spanning a wavelength range from FUV to optical, and remain consistent with Hα data. We have achieved an excellent match of the P V λλ1118, 1128 resonance doublet and N IV λ1718, as well as He II λ4686 suggesting that our physical description of clumping is adequate. We find very small volume filling factors and that clumping starts deep in the wind, near the sonic point. The most crucial consequence of our analysis is that the mass loss rates of O stars need to be revised downward significantly, by a factor of 3 and more compared to those obtained from smooth-wind models. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17662 ER - TY - CHAP A1 - Urbaneja, M. A. A1 - Kudritzki, R.-P. A1 - Puls, Joachim T1 - Clumping in the winds of O-type CSPNs N2 - Recent studies of massive O-type stars present clear evidences of inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary nebulae (CSPNs) are in some ways the low mass–low luminosity analogous of those massive stars. In this contribution, we present preliminary results of our on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic CSPNs. Particular emphasis will be given to the clumping factors derived by means of optical lines (Hα and Heii 4686) and “classic” FUV (and UV) lines. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17801 ER - TY - JOUR A1 - Kühne, Franziska A1 - Fauth, Henriette A1 - Destina Sevde, Ay-Bryson A1 - Visser, Leonie N.C. A1 - Weck, Florian T1 - Communicating the diagnosis of cancer or depression: Results of a randomized controlled online study using video vignettes JF - Cancer Medicine N2 - Background Communicating a diagnosis is highly important, yet complex, especially in the context of cancer and mental disorders. The aim was to explore the communication style of an oncologist vs. psychotherapist in an online study. Methods Patients (N = 136: 65 cancer, 71 depression) were randomly assigned to watch a standardized video vignette with one of two communication styles (empathic vs. unempathic). Outcome measures of affectivity, information recall, communication skills, empathy and trust were applied. Results Regardless of diagnosis, empathic communication was associated with the perception of a significantly more empathic (p < 0.001, η2partial = 0.08) and trustworthy practitioner (p = 0.014, η2partial = 0.04) with better communication skills (p = 0.013, η2partial = 0.05). Cancer patients reported a larger decrease in positive affect (p < 0.001, η2partial = 0.15) and a larger increase in negative affect (p < 0.001, η2partial = 0.14) from pre- to post-video than depressive patients. Highly relevant information was recalled better in both groups (p < 0.001, d = 0.61–1.06). Conclusions The results highlight the importance of empathy while communicating both a diagnosis of cancer and a mental disorder. Further research should focus on the communication of a mental disorder in association with cancer. KW - consultation KW - mental health KW - oncology KW - psycho-oncology KW - skills Y1 - 2021 U6 - https://doi.org/10.1002/cam4.4396 SN - 2045-7634 VL - 10 SP - 9012 EP - 9021 PB - Wiley CY - Hoboken, New Jersey, USA ET - 24 ER - TY - THES A1 - Hoffmann, Anne T1 - Comparative aerosol studies based on multi-wavelength Raman LIDAR at Ny-Ålesund, Spitsbergen T1 - Vergleichende Aerosolstudien mittels Mehrwellenlängen-Raman-LIDAR in Ny-Ålesund,Spitzbergen N2 - The Arctic is a particularly sensitive area with respect to climate change due to the high surface albedo of snow and ice and the extreme radiative conditions. Clouds and aerosols as parts of the Arctic atmosphere play an important role in the radiation budget, which is, as yet, poorly quantified and understood. The LIDAR (Light Detection And Ranging) measurements presented in this PhD thesis contribute with continuous altitude resolved aerosol profiles to the understanding of occurrence and characteristics of aerosol layers above Ny-Ålesund, Spitsbergen. The attention was turned to the analysis of periods with high aerosol load. As the Arctic spring troposphere exhibits maximum aerosol optical depths (AODs) each year, March and April of both the years 2007 and 2009 were analyzed. Furthermore, stratospheric aerosol layers of volcanic origin were analyzed for several months, subsequently to the eruptions of the Kasatochi and Sarychev volcanoes in summer 2008 and 2009, respectively. The Koldewey Aerosol Raman LIDAR (KARL) is an instrument for the active remote sensing of atmospheric parameters using pulsed laser radiation. It is operated at the AWIPEV research base and was fundamentally upgraded within the framework of this PhD project. It is now equipped with a new telescope mirror and new detection optics, which facilitate atmospheric profiling from 450m above sea level up to the mid-stratosphere. KARL provides highly resolved profiles of the scattering characteristics of aerosol and cloud particles (backscattering, extinction and depolarization) as well as water vapor profiles within the lower troposphere. Combination of KARL data with data from other instruments on site, namely radiosondes, sun photometer, Micro Pulse LIDAR, and tethersonde system, resulted in a comprehensive data set of scattering phenomena in the Arctic atmosphere. The two spring periods March and April 2007 and 2009 were at first analyzed based on meteorological parameters, like local temperature and relative humidity profiles as well as large scale pressure patterns and air mass origin regions. Here, it was not possible to find a clear correlation between enhanced AOD and air mass origin. However, in a comparison of two cloud free periods in March 2007 and April 2009, large AOD values in 2009 coincided with air mass transport through the central Arctic. This suggests the occurrence of aerosol transformation processes during the aerosol transport to Ny-Ålesund. Measurements on 4 April 2009 revealed maximum AOD values of up to 0.12 and aerosol size distributions changing with altitude. This and other performed case studies suggest the differentiation between three aerosol event types and their origin: Vertically limited aerosol layers in dry air, highly variable hygroscopic boundary layer aerosols and enhanced aerosol load across wide portions of the troposphere. For the spring period 2007, the available KARL data were statistically analyzed using a characterization scheme, which is based on optical characteristics of the scattering particles. The scheme was validated using several case studies. Volcanic eruptions in the northern hemisphere in August 2008 and June 2009 arose the opportunity to analyze volcanic aerosol layers within the stratosphere. The rate of stratospheric AOD change was similar within both years with maximum values above 0.1 about three to five weeks after the respective eruption. In both years, the stratospheric AOD persisted at higher rates than usual until the measurements were stopped in late September due to technical reasons. In 2008, up to three aerosol layers were detected, the layer structure in 2009 was characterized by up to six distinct and thin layers which smeared out to one broad layer after about two months. The lowermost aerosol layer was continuously detected at the tropopause altitude. Three case studies were performed, all revealed rather large indices of refraction of m = (1.53–1.55) - 0.02i, suggesting the presence of an absorbing carbonaceous component. The particle radius, derived with inversion calculations, was also similar in both years with values ranging from 0.16 to 0.19 μm. However, in 2009, a second mode in the size distribution was detected at about 0.5 μm. The long term measurements with the Koldewey Aerosol Raman LIDAR in Ny-Ålesund provide the opportunity to study Arctic aerosols in the troposphere and the stratosphere not only in case studies but on longer time scales. In this PhD thesis, both, tropospheric aerosols in the Arctic spring and stratospheric aerosols following volcanic eruptions have been described qualitatively and quantitatively. Case studies and comparative studies with data of other instruments on site allowed for the analysis of microphysical aerosol characteristics and their temporal evolution. N2 - Die Arktis ist ein bezüglich Klimaveränderungen besonders sensitives Gebiet, d.h. die globale Erwärmung wirkt sich aufgrund der saisonal hochvariablen Strahlungsbedingungen und der Bodenalbedo dort verstärkt aus.Wolken und Aerosole als Bestandteile der arktischen Atmosphäre spielen dabei eine besondere Rolle im Strahlungsgleichgewicht. Die vorliegende Promotionsarbeit leistet mit Hilfe von LIDAR-Messungen (Light Detection and Ranging) einen Beitrag zum Verständnis von Vorkommen und Eigenschaften von Aerosolschichten über Ny-Ålesund, Spitzbergen. Besonderes Augenmerk liegt dabei auf der Analyse von Zeiträumen mit erhöhter Aerosolbelastung. Es wurde zum einen die arktische Troposphäre zweier Frühjahre (März und April der Jahre 2007 und 2009) untersucht, da im Frühjahr die Aerosol-optische Dicke (AOD) in der Arktis Maximalwerte erreicht. Zum anderen wurden stratosphärische Aerosolschichten vulkanischen Ursprungs analysiert, die in den Sommern 2008 und 2009 nach Ausbrüchen der Kasatochi und Sarychev Vulkane jeweils für mehrere Monate in der unteren Stratosphäre messbar waren. Das an der AWIPEV Forschungsstation betriebene Koldewey Aerosol Raman LIDAR (KARL), ein Instrument zur optischen Fernerkundung atmosphärischer Parameter mittels gepulster Laserstrahlung, wurde im Rahmen der Promotion grundlegend überarbeitet und mit einem neuen Teleskop sowie neuen Detektoroptiken versehen. Dies ermöglicht die Profilerfassung ab 450m über dem Meeresspiegel bis in die mittlere Stratosphäre. KARL liefert hochaufgelöste Messungen der Streueigenschaften von Aerosol- undWolkenteilchen (Rückstreuung, Extinktion und Depolarisation) sowieWasserdampfprofile in der unteren Troposphäre. Durch die Kombination von KARL Messungen mit Daten anderer Messgeräte an der AWIPEV Forschungsstation wie Radiosonden, Sonnenphotometer, Micro Pulse LIDAR und Fesselsonden wurde ein umfassender Datenbestand von Streuphänomenen in der arktischen Atmosphäre geschaffen. Die beiden genannten Frühjahreszeiträume März und April 2007 und 2009 wurden zunächst anhand meteorologischer Parameter, wie lokaler Temperatur- und Feuchteprofile sowie großskaliger Druckmuster und Luftmassenquellgebiete analysiert. Dabei konnte kein eindeutiger Zusammenhang zwischen Quellgebieten und erhöhter AOD festgestellt werden. In einem Vergleich zweier wolkenfreier Perioden im März 2007 und April 2009 war jedoch die höhere Aerosolbelastung in 2009 mit dem Transport von Luftmassen durch die innere Arktis verbunden. Aufgrund der begrenzten Lebensdauer von Aerosolen lässt das entweder Aerosol-Entstehungsprozesse in der Zentralarktis oder Transformationsprozesse während des Transportes nach Ny-Ålesund vermuten. Für Messungen am 4. April 2009 mit Maximalwerten der AOD von bis zu 0.12 konnte die Größe der Aerosolteilchen in verschiedenen Höhen mit Hilfe von Inversionsrechnungen abgeschätzt werden. Diese und andere betrachtete Fallstudien legen eine Unterscheidung von Aerosolereignissen in drei Kategorien nahe, die sich in ihrer Entstehung deutlich unterscheiden: Vertikal begrenzte Aeosolschichten in trockener Luft, zeitlich hochvariable feuchte Aerosolschichten in der planetaren Grenzschicht sowie eine erhöhte Aerosolbelastung über große Teile der Troposphäre. Für das sehr klare Frühjahr 2007 wurden die vorhandenen KARL-Daten mit Hilfe eines Klassifikationsschemas, das auf den optischen Eigenschaften der streuenden Teilchen beruht, statistisch ausgewertet. Das verwendete Schema wurde mit Hilfe von verschiedenen Fallstudien validiert und ermöglicht bei Anwendung auf größere Datenbestände eine aussagekräftige Analyse von jährlichen Schwankungen der Aerosol- und Wolkenvorkommen über Ny-Ålesund. Die Ausbrüche zweier Vulkane in der nördlichen Hemisphäre im August 2008 und im Juni 2009 erlaubten die Analyse vulkanischer Aerosolschichten in der Stratosphäre. Die zeitliche Entwicklung der stratosphärischen AOD verlief in beiden Jahren ähnlich mit Maximalwerten von über 0.1 etwa drei bis fünfWochen nach dem jeweiligen Ausbruch. In beiden Jahren wurden bis zum technisch bedingten Abbruch der Messungen jeweils Ende September erhöhte stratosphärische AOD Werte gemessen. Die niedrigste Aerosolschicht konnte jeweils direkt an der Tropopause detektiert werden. Im Jahr 2008 wurden bis zu drei Schichten detektiert, die Struktur 2009 war durch bis zu sechs schmale Schichten gekennzeichnet, die nach etwa zwei Monaten zu einer breiten Schicht verschmierten. Drei Fallstudien zu mikrophysikalischen Aerosoleigenschaften wurden durchgeführt. Dabei wurden für beide Jahre sehr große Brechungsindices von m=(1.53–1.55) - 0.02i ermittelt, die auf eine absorbierende Kohlenstoffkomponente der Vulkanaerosole hinweisen. Der errechnete Teilchenradius war ebenfalls in beiden Jahren vergleichbar mit Werten zwischen 0.16 und 0.19 μm. 2009 wurde zusätzlich ein zweites Maximum der Größenverteilung bei ca. 0.5μm gefunden. Die Langzeitmessungen mit dem Koldewey Aerosol Raman LIDAR KARL in Ny-Ålesund schaffen die Möglichkeit, arktische Aerosole in Troposphäre und Stratosphäre nicht nur in Fallstudien, sondern auch über längere Zeiträume hinweg zu analysieren. Im Rahmen dieser Promotionsarbeit konnten sowohl Aerosolvorkommen in der arktischen Troposphäre im Frühjahr als auch eine vulkanisch bedingte erhöhte Aerosolbelastung in der Stratosphäre qualitativ und quantitativ beschrieben werden. Fallstudien und die Kombination mit Daten anderer Messgeräte ermöglichten Analysen mikrophysikalischer Aerosolparameter und deren Entwicklungsprozesse. KW - Arktis KW - Lidar KW - Aerosole KW - Fernerkundung KW - Arctic KW - Lidar KW - Aerosols KW - Remote Sensing Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-52426 ER - TY - THES A1 - Donges, Jonathan T1 - Complex networks in the climate system N2 - Complex network theory provides an elegant and powerful framework to statistically investigate the topology of local and long range dynamical interrelationships, i.e., teleconnections, in the climate system. Employing a refined methodology relying on linear and nonlinear measures of time series analysis, the intricate correlation structure within a multivariate climatological data set is cast into network form. Within this graph theoretical framework, vertices are identified with grid points taken from the data set representing a region on the the Earth's surface, and edges correspond to strong statistical interrelationships between the dynamics on pairs of grid points. The resulting climate networks are neither perfectly regular nor completely random, but display the intriguing and nontrivial characteristics of complexity commonly found in real world networks such as the internet, citation and acquaintance networks, food webs and cortical networks in the mammalian brain. Among other interesting properties, climate networks exhibit the "small-world" effect and possess a broad degree distribution with dominating super-nodes as well as a pronounced community structure. We have performed an extensive and detailed graph theoretical analysis of climate networks on the global topological scale focussing on the flow and centrality measure betweenness which is locally defined at each vertex, but includes global topological information by relying on the distribution of shortest paths between all pairs of vertices in the network. The betweenness centrality field reveals a rich internal structure in complex climate networks constructed from reanalysis and atmosphere-ocean coupled general circulation model (AOGCM) surface air temperature data. Our novel approach uncovers an elaborately woven meta-network of highly localized channels of strong dynamical information flow, that we relate to global surface ocean currents and dub the backbone of the climate network in analogy to the homonymous data highways of the internet. This finding points to a major role of the oceanic surface circulation in coupling and stabilizing the global temperature field in the long term mean (140 years for the model run and 60 years for reanalysis data). Carefully comparing the backbone structures detected in climate networks constructed using linear Pearson correlation and nonlinear mutual information, we argue that the high sensitivity of betweenness with respect to small changes in network structure may allow to detect the footprints of strongly nonlinear physical interactions in the climate system. The results presented in this thesis are thoroughly founded and substantiated using a hierarchy of statistical significance tests on the level of time series and networks, i.e., by tests based on time series surrogates as well as network surrogates. This is particularly relevant when working with real world data. Specifically, we developed new types of network surrogates to include the additional constraints imposed by the spatial embedding of vertices in a climate network. Our methodology is of potential interest for a broad audience within the physics community and various applied fields, because it is universal in the sense of being valid for any spatially extended dynamical system. It can help to understand the localized flow of dynamical information in any such system by combining multivariate time series analysis, a complex network approach and the information flow measure betweenness centrality. Possible fields of application include fluid dynamics (turbulence), plasma physics and biological physics (population models, neural networks, cell models). Furthermore, the climate network approach is equally relevant for experimental data as well as model simulations and hence introduces a novel perspective on model evaluation and data driven model building. Our work is timely in the context of the current debate on climate change within the scientific community, since it allows to assess from a new perspective the regional vulnerability and stability of the climate system while relying on global and not only on regional knowledge. The methodology developed in this thesis hence has the potential to substantially contribute to the understanding of the local effect of extreme events and tipping points in the earth system within a holistic global framework. N2 - Die Theorie komplexer Netzwerke bietet einen eleganten Rahmen zur statistischen Untersuchung der Topologie lokaler und langreichweitiger dynamischer Zusammenhänge (Telekonnektionen) im Klimasystem. Unter Verwendung einer verfeinerten, auf linearen und nichtlinearen Korrelationsmaßen der Zeitreihenanalyse beruhenden Netzwerkkonstruktionsmethode, bilden wir die komplexe Korrelationsstruktur eines multivariaten klimatologischen Datensatzes auf ein Netzwerk ab. Dabei identifizieren wir die Knoten des Netzwerkes mit den Gitterpunkten des zugrundeliegenden Datensatzes, während wir Paare von besonders stark korrelierten Knoten als Kanten auffassen. Die resultierenden Klimanetzwerke zeigen weder die perfekte Regularität eines Kristallgitters, noch eine vollkommen zufällige Topologie. Vielmehr weisen sie faszinierende und nichttriviale Eigenschaften auf, die charakteristisch für natürlich gewachsene Netzwerke wie z.B. das Internet, Zitations- und Bekanntschaftsnetzwerke, Nahrungsnetze und kortikale Netzwerke im Säugetiergehirn sind. Besonders erwähnenswert ist, dass in Klimanetzwerken das Kleine-Welt-Phänomen auftritt. Desweiteren besitzen sie eine breite Gradverteilung, werden von Superknoten mit sehr vielen Nachbarn dominiert, und bilden schließlich regional wohldefinierte Untergruppen von intern dicht vernetzten Knoten aus. Im Rahmen dieser Arbeit wurde eine detaillierte, graphentheoretische Analyse von Klimanetzwerken auf der globalen topologischen Skala durchgeführt, wobei wir uns auf das Netzwerkfluss- und Zentralitätsmaß Betweenness konzentrierten. Betweenness ist zwar lokal an jedem Knoten definiert, enthält aber trotzdem Informationen über die globale Netzwerktopologie. Dies beruht darauf, dass die Verteilung kürzester Pfade zwischen allen möglichen Paaren von Knoten in die Berechnung des Maßes eingeht. Das Betweennessfeld zeigt reichhaltige und zuvor verborgene Strukturen in aus Reanalyse- und Modelldaten der erdoberflächennahen Lufttemperatur gewonnenen Klimanetzen. Das durch unseren neuartigen Ansatz enthüllte Metanetzwerk, bestehend aus hochlokalisierten Kanälen stark gebündelten Informationsflusses, bringen wir mit der Oberflächenzirkulation des Weltozeans in Verbindung. In Analogie mit den gleichnamigen Datenautobahnen des Internets nennen wir dieses Metanetzwerk den Backbone des Klimanetzwerks. Unsere Ergebnisse deuten insgesamt darauf hin, dass Meeresoberflächenströmungen einen wichtigen Beitrag zur Kopplung und Stabilisierung des globalen Oberflächenlufttemperaturfeldes leisten. Wir zeigen weiterhin, dass die hohe Sensitivität des Betweennessmaßes hinsichtlich kleiner Änderungen der Netzwerktopologie die Detektion stark nichtlinearer physikalischer Wechselwirkungen im Klimasystem ermöglichen könnte. Die in dieser Arbeit vorgestellten Ergebnisse wurden mithilfe statistischer Signifikanztests auf der Zeitreihen- und Netzwerkebene gründlich auf ihre Robustheit geprüft. In Anbetracht fehlerbehafteter Daten und komplexer statistischer Zusammenhänge zwischen verschiedenen Netzwerkmaßen ist diese Vorgehensweise besonders wichtig. Weiterhin ist die Entwicklung neuer, allgemein anwendbarer Surrogate für räumlich eingebettete Netzwerke hervorzuheben, die die Berücksichtigung spezieller Klimanetzwerkeigenschaften wie z.B. der Wahrscheinlichkeitsverteilung der Kantenlängen erlauben. Unsere Methode ist universell, weil sie zum Verständnis des lokalisierten Informationsflusses in allen räumlich ausgedehnten, dynamischen Systemen beitragen kann. Deshalb ist sie innerhalb der Physik und anderer angewandter Wissenschaften von potentiell breitem Interesse. Mögliche Anwendungen könnten sich z.B. in der Fluiddynamik (Turbulenz), der Plasmaphysik und der Biophysik (Populationsmodelle, neuronale Netzwerke und Zellmodelle) finden. Darüber hinaus ist der Netzwerkansatz für experimentelle Daten sowie Modellsimulationen gültig, und eröffnet folglich neue Perspektiven für Modellevaluation und datengetriebene Modellierung. Im Rahmen der aktuellen Klimawandeldebatte stellen Klimanetzwerke einen neuartigen Satz von Analysemethoden zur Verfügung, der die Evaluation der lokalen Vulnerabilität und Stabilität des Klimasystems unter Berücksichtigung globaler Randbedingungen ermöglicht. Die in dieser Arbeit entwickelten und untersuchten Methoden könnten folglich in der Zukunft, innerhalb eines holistisch-globalen Ansatzes, zum Verständnis der lokalen Auswirkungen von Extremereignissen und Kipppunkten im Erdsystem beitragen. KW - Komplexe Netzwerke KW - Klimanetzwerke KW - Datenanalyse KW - Graphentheorie KW - Klimadaten KW - Complex networks KW - climate networks KW - data analysis KW - graph theory KW - climate data Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-49775 ER - TY - JOUR A1 - Weithoff, Guntram A1 - Bell, Elanor Margaret T1 - Complex Trophic Interactions in an Acidophilic Microbial Community JF - Microorganisms N2 - Extreme habitats often harbor specific communities that differ substantially from non-extreme habitats. In many cases, these communities are characterized by archaea, bacteria and protists, whereas the number of species of metazoa and higher plants is relatively low. In extremely acidic habitats, mostly prokaryotes and protists thrive, and only very few metazoa thrive, for example, rotifers. Since many studies have investigated the physiology and ecology of individual species, there is still a gap in research on direct, trophic interactions among extremophiles. To fill this gap, we experimentally studied the trophic interactions between a predatory protist (Actinophrys sol, Heliozoa) and its prey, the rotifers Elosa woralli and Cephalodella sp., the ciliate Urosomoida sp. and the mixotrophic protist Chlamydomonas acidophila (a green phytoflagellate, Chlorophyta). We found substantial predation pressure on all animal prey. High densities of Chlamydomonas acidophila reduced the predation impact on the rotifers by interfering with the feeding behaviour of A. sol. These trophic relations represent a natural case of intraguild predation, with Chlamydomonas acidophila being the common prey and the rotifers/ciliate and A. sol being the intraguild prey and predator, respectively. We further studied this intraguild predation along a resource gradient using Cephalodella sp. as the intraguild prey. The interactions among the three species led to an increase in relative rotifer abundance with increasing resource (Chlamydomonas) densities. By applying a series of laboratory experiments, we revealed the complexity of trophic interactions within a natural extremophilic community. KW - acid mine drainage KW - extremophiles KW - food web KW - heliozoa KW - intraguild predation KW - mining lakes KW - Rotifera Y1 - 2022 U6 - https://doi.org/10.3390/microorganisms10071340 SN - 2076-2607 VL - 10 SP - 1 EP - 10 PB - MDPI CY - Basel, Schweiz ET - 7 ER - TY - JOUR A1 - Perscheid, Cindy T1 - Comprior BT - Facilitating the implementation and automated benchmarking of prior knowledge-based feature selection approaches on gene expression data sets JF - BMC Bioinformatics N2 - Background Reproducible benchmarking is important for assessing the effectiveness of novel feature selection approaches applied on gene expression data, especially for prior knowledge approaches that incorporate biological information from online knowledge bases. However, no full-fledged benchmarking system exists that is extensible, provides built-in feature selection approaches, and a comprehensive result assessment encompassing classification performance, robustness, and biological relevance. Moreover, the particular needs of prior knowledge feature selection approaches, i.e. uniform access to knowledge bases, are not addressed. As a consequence, prior knowledge approaches are not evaluated amongst each other, leaving open questions regarding their effectiveness. Results We present the Comprior benchmark tool, which facilitates the rapid development and effortless benchmarking of feature selection approaches, with a special focus on prior knowledge approaches. Comprior is extensible by custom approaches, offers built-in standard feature selection approaches, enables uniform access to multiple knowledge bases, and provides a customizable evaluation infrastructure to compare multiple feature selection approaches regarding their classification performance, robustness, runtime, and biological relevance. Conclusion Comprior allows reproducible benchmarking especially of prior knowledge approaches, which facilitates their applicability and for the first time enables a comprehensive assessment of their effectiveness KW - Feature selection KW - Prior knowledge KW - Gene expression KW - Reproducible benchmarking Y1 - 2021 U6 - https://doi.org/10.1186/s12859-021-04308-z SN - 1471-2105 VL - 22 SP - 1 EP - 15 PB - Springer Nature CY - London ER - TY - JOUR A1 - Grgurina, Nataša T1 - Computational thinking in Dutch secondary education JF - Commentarii informaticae didacticae : (CID) N2 - We shall examine the Pedagogical Content Knowledge (PCK) of Computer Science (CS) teachers concerning students’ Computational Thinking (CT) problem solving skills within the context of a CS course in Dutch secondary education and thus obtain an operational definition of CT and ascertain appropriate teaching methodology. Next we shall develop an instrument to assess students’ CT and design a curriculum intervention geared toward teaching and improving students’ CT problem solving skills and competences. As a result, this research will yield an operational definition of CT, knowledge about CT PCK, a CT assessment instrument and teaching materials and accompanying teacher instructions. It shall contribute to CS teacher education, development of CT education and to education in other (STEM) subjects where CT plays a supporting role, both nationally and internationally. KW - computational thinking KW - situated learning KW - engaged computing KW - computer science Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-64556 SN - 1868-0844 SN - 2191-1940 IS - 6 SP - 119 EP - 123 PB - Universitätsverlag Potsdam CY - Potsdam ER -