@phdthesis{Nowak2020, author = {Nowak, Jacqueline}, title = {Devising computational tools to quantify the actin cytoskeleton and pavement cell shape using network-based approaches}, school = {Universit{\"a}t Potsdam}, pages = {123}, year = {2020}, abstract = {Recent advances in microscopy have led to an improved visualization of different cell processes. Yet, this also leads to a higher demand of tools which can process images in an automated and quantitative fashion. Here, we present two applications that were developed to quantify different processes in eukaryotic cells which rely on the organization and dynamics of the cytoskeleton.. In plant cells, microtubules and actin filaments form the backbone of the cytoskeleton. These structures support cytoplasmic streaming, cell wall organization and tracking of cellular material to and from the plasma membrane. To better understand the underlying mechanisms of cytoskeletal organization, dynamics and coordination, frameworks for the quantification are needed. While this is fairly well established for the microtubules, the actin cytoskeleton has remained difficult to study due to its highly dynamic behaviour. One aim of this thesis was therefore to provide an automated framework to quantify and describe actin organization and dynamics. We used the framework to represent actin structures as networks and examined the transport efficiency in Arabidopsis thaliana hypocotyl cells. Furthermore, we applied the framework to determine the growth mode of cotton fibers and compared the actin organization in wild-type and mutant cells of rice. Finally, we developed a graphical user interface for easy usage. Microtubules and the actin cytoskeleton also play a major role in the morphogenesis of epidermal leaf pavement cells. These cells have highly complex and interdigitated shapes which are hard to describe in a quantitative way. While the relationship between microtubules, the actin cytoskeleton and shape formation is the object of many studies, it is still not clear how and if the cytoskeletal components predefine indentations and protrusions in pavement cell shapes. To understand the underlying cell processes which coordinate cell morphogenesis, a quantitative shape descriptor is needed. Therefore, the second aim of this thesis was the development of a network-based shape descriptor which captures global and local shape features, facilitates shape comparison and can be used to evaluate shape complexity. We demonstrated that our framework can be used to describe and compare shapes from various domains. In addition, we showed that the framework accurately detects local shape features of pavement cells and outperform contending approaches. In the third part of the thesis, we extended the shape description framework to describe pavement cell shape features on tissue-level by proposing different network representations of the underlying imaging data.}, language = {en} } @phdthesis{Marquart2019, author = {Marquart, Arnim}, title = {Feedbacks between macropores and soil water infiltration in semi-arid savanna systems}, pages = {146}, year = {2019}, language = {en} } @phdthesis{Paraskevopoulou2019, author = {Paraskevopoulou, Sofia}, title = {Adaptive genetic variation and responses to thermal stress in brachionid rotifers}, pages = {IV, 177}, year = {2019}, abstract = {The importance of cryptic diversity in rotifers is well understood regarding its ecological consequences, but there remains an in depth comprehension of the underlying molecular mechanisms and forces driving speciation. Temperature has been found several times to affect species spatio-temporal distribution and organisms' performance, but we lack information on the mechanisms that provide thermal tolerance to rotifers. High cryptic diversity was found recently in the freshwater rotifer "Brachionus calyciflorus", showing that the complex comprises at least four species: B. calyciflorus sensu stricto (s.s.), B. fernandoi, B. dorcas, and B. elevatus. The temporal succession among species which have been observed in sympatry led to the idea that temperature might play a crucial role in species differentiation. The central aim of this study was to unravel differences in thermal tolerance between species of the former B. calyciflorus species complex by comparing phenotypic and gene expression responses. More specifically, I used the critical maximum temperature as a proxy for inter-species differences in heat-tolerance; this was modeled as a bi-dimensional phenotypic trait taking into consideration the intention and the duration of heat stress. Significant differences on heat-tolerance between species were detected, with B. calyciflorus s.s. being able to tolerate higher temperatures than B. fernandoi. Based on evidence of within species neutral genetic variation, I further examined adaptive genetic variability within two different mtDNA lineages of the heat tolerant B. calyciflorus s.s. to identify SNPs and genes under selection that might reflect their adaptive history. These analyses did not reveal adaptive genetic variation related to heat, however, they show putatively adaptive genetic variation which may reflect local adaptation. Functional enrichment of putatively positively selected genes revealed signals of adaptation in genes related to "lipid metabolism", "xenobiotics biodegradation and metabolism" and "sensory system", comprising candidate genes which can be utilized in studies on local adaptation. An absence of genetically-based differences in thermal adaptation between the two mtDNA lineages, together with our knowledge that B. calyciflorus s.s. can withstand a broad range of temperatures, led to the idea to further investigate shared transcriptomic responses to long-term exposure to high and low temperatures regimes. With this, I identified candidate genes that are involved in the response to temperature imposed stress. Lastly, I used comparative transcriptomics to examine responses to imposed heat-stress in heat-tolerant and heat-sensitive Brachionus species. I found considerably different patterns of gene expression in the two species. Most striking are patterns of expression regarding the heat shock proteins (hsps) between the two species. In the heat-tolerant, B. calyciflorus s.s., significant up-regulation of hsps at low temperatures was indicative of a stress response at the cooler end of the temperature regimes tested here. In contrast, in the heat-sensitive B. fernandoi, hsps generally exhibited up-regulation of these genes along with rising temperatures. Overall, identification of differences in expression of genes suggests suppression of protein biosynthesis to be a mechanism to increase thermal tolerance. Observed patterns in population growth are correlated with the hsp gene expression differences, indicating that this physiological stress response is indeed related to phenotypic life history performance.}, language = {en} } @phdthesis{Scianna2019, author = {Scianna, Bastian Matteo}, title = {The Italian war on the eastern front, 1941-1943}, series = {Italian and Italian American Studies}, journal = {Italian and Italian American Studies}, publisher = {Palgrave Macmillan}, address = {Cham}, isbn = {978-3-03026-523-6}, pages = {365}, year = {2019}, abstract = {The Italian Army's participation in Hitler's war against the Soviet Union has remained unrecognized and understudied. Bastian Matteo Scianna offers a wide-ranging, in-depth corrective. Mining Italian, German and Russian sources, he examines the history of the Italian campaign in the East between 1941 and 1943, as well as how the campaign was remembered and memorialized in the domestic and international arena during the Cold War. Linking operational military history with memory studies, this book revises our understanding of the Italian Army in the Second World War.}, language = {en} } @phdthesis{Lehmann2018, author = {Lehmann, Andreas}, title = {Variability in human life history traits}, school = {Universit{\"a}t Potsdam}, pages = {110}, year = {2018}, language = {de} } @phdthesis{Homeyer2018, author = {Homeyer, Marc S{\"o}ren}, title = {Photometrische Bestimmungen mittels eines modifizierten Sch{\"u}lerphotometers und naturwissenschaftliches Arbeiten im Seminarkurs}, address = {119, A 203}, year = {2018}, language = {de} } @phdthesis{Schuster2017, author = {Schuster, Isabell}, title = {Prevalence and Predictors of Sexual Aggression Victimization and Perpetration in Chile and Turkey}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-413897}, school = {Universit{\"a}t Potsdam}, pages = {285}, year = {2017}, abstract = {Background: Although sexual aggression is recognized as a serious issue worldwide, the current knowledge base is primarily built on evidence from Western countries, particularly the U.S. For the present doctoral research, Chile and Turkey were selected based on theoretical considerations to examine the prevalence as well as predictors of sexual aggression victimization and perpetration. The first aim of this research project was to systematically review the available evidence provided by past studies on this topic within each country. The second aim was to empirically study the prevalence of experiencing and engaging in sexual aggression since the age of consent among college students in Chile and Turkey. The third aim was to conduct cross-cultural analyses examining pathways to victimization and perpetration based on a two-wave longitudinal design. Methods: This research adopted a gender-inclusive approach by considering men and women in both victim and perpetrator roles. For the systematic reviews, multiple-stage literature searches were performed, and based on a predefined set of eligibility criteria, 28 studies in Chile and 56 studies in Turkey were identified for inclusion. A two-wave longitudinal study was conducted to examine the prevalence and predictors of sexual aggression among male and female college students in Chile and Turkey. Self-reports of victimization and perpetration were assessed with a Chilean Spanish or Turkish version of the Sexual Aggression and Victimization Scale. Two path models were conceptualized in which participants' risky sexual scripts for consensual sex, risky sexual behavior, sexual self-esteem, sexual assertiveness, and religiosity were assessed at T1 and used as predictors of sexual aggression victimization and perpetration at T2 in the following 12 months, mediated through past victimization or perpetration, respectively. The models differed in that sexual assertiveness was expected to serve different functions for victimization (refusal assertiveness negatively linked to victimization) and perpetration (initiation assertiveness positively linked to perpetration). Results: Both systematic reviews revealed that victimization was addressed by all included studies, but data on perpetration was severely limited. A great heterogeneity not only in victimization rates but also in predictors was found, which may be attributed to a lack of conceptual and methodological consistency across studies. The empirical analysis of the prevalence of sexual aggression in Chile revealed a victimization rate of 51.9\% for women and 48.0\% for men, and a perpetration rate of 26.8\% for men and 16.5\% for women. In the Turkish original data, victimization was reported by 77.6\% of women and 65.5\% of men, whereas, again, lower rates were found for perpetration, with 28.9\% of men and 14.2\% of women reporting at least one incident. The cross-cultural analyses showed, as expected, that risky sexual scripts informed risky sexual behavior, and thereby indirectly increased the likelihood of victimization and perpetration at T2 in both samples. More risky sexual scripts were also linked to lower levels of refusal assertiveness in both samples, indirectly increasing the vulnerability to victimization at T2. High sexual self-esteem decreased the probability of victimization at T2 through higher refusal assertiveness as well as through less risky sexual behavior also in both samples, whereas it increased the odds of perpetration at T2 via higher initiation assertiveness in the Turkish sample only. Furthermore, high religiosity decreased the odds of perpetration and victimization at T2 through less risky sexual scripts and less risky sexual behavior in both samples. It reduced the vulnerability to victimization through less risky sexual scripts and higher refusal assertiveness in the Chilean sample only. In the Turkish sample only, it increased the odds of perpetration and victimization through lower sexual self-esteem. Conclusions: The findings showed that sexual aggression is a widespread problem in both Chile and Turkey, contributing cross-cultural evidence to the international knowledge base and indicating the clear need for implementing policy measures and prevention strategies in each country. Based on the results of the prospective analyses, concrete implications for intervention efforts are discussed.}, language = {en} } @phdthesis{Behrens2018, author = {Behrens, Ricarda}, title = {Causes for slow weathering and erosion in the steep, warm, monsoon-subjected Highlands of Sri Lanka}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408503}, school = {Universit{\"a}t Potsdam}, pages = {ix, 107, XXIV}, year = {2018}, abstract = {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.}, language = {en} } @phdthesis{Berding2017, author = {Berding, Anja}, title = {Kurz-, mittel- und langfristige Effekte einer Schulung f{\"u}r Patienten mit chronisch entz{\"u}ndlichen Darmerkrankungen auf krankheitsbezogene {\"A}ngste und Gesundheitskompetenzen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-401063}, school = {Universit{\"a}t Potsdam}, pages = {V, 118}, year = {2017}, abstract = {Menschen mit chronisch entz{\"u}ndlichen Darmerkrankungen (CED) leiden unter vielf{\"a}ltigen k{\"o}rperlichen und psychosozialen Einschr{\"a}nkungen. Wie auch bei anderen chronischen Erkrankungen k{\"o}nnten Patientenschulungen ihr psychisches Befinden verbessern (z.B. De Ridder \& Schreurs, 2001; Faller, Reusch \& Meng, 2011a; K{\"u}ver, Becker \& Ludt, 2008; Sch{\"u}ssler, 1998; Warsi, Wang, LaValley, Avorn \& Solomon, 2004). F{\"u}r CED liegen jedoch nur wenige Schulungsevaluationen vor (z.B. Bregenzer et al., 2005; Mussell, B{\"o}cker, Nagel, Olbrich \& Singer, 2003; Oxelmark, Magnusson, L{\"o}fberg \& Hiller{\aa}s, 2007), deren Aussagekraft i.d.R. durch methodische M{\"a}ngel eingeschr{\"a}nkt ist. Daher ist die Bedeutung von Schulungsprogrammen f{\"u}r CED-Betroffene weiterhin offen. {\"U}berdies gibt es f{\"u}r den deutschen Sprachraum noch keine Schulung, die zu psychischen Verbesserungen f{\"u}hrt. Aus diesem Grunde wurde ein 1,5-t{\"a}giges Wochenend-Seminar mit medizinischen und psychologischen Inhalten konzeptionalisiert, manualisiert und in der vorliegenden Studie evaluiert. Zur summativen Evaluation nahmen 181 ambulante CED-Patienten an einer prospektiven, multizentrischen, randomisierten, kontrollierten Studie mit vier Messzeitpunkten teil: vor (T1), zwei Wochen (T2) und drei Monate (T3) nach dem Seminar. Zur 12-Monatskatamnese (T4EG) wurde die Stabilit{\"a}t der Effekte in der Experimentalgruppe (EG; n = 86) {\"u}berpr{\"u}ft. Die Wartekontrollgruppe (n = 95) erhielt zun{\"a}chst die Standardbehandlung, also keine Patientenschulung, und konnte an dieser nach der dritten Datenerhebung ebenfalls teilnehmen. Kovarianzanalysen (ANCOVAs) mit Kontrolle f{\"u}r die jeweilige Ausgangslage wurden durchgef{\"u}hrt. Weitere Analysen legten eine Adjustierung f{\"u}r die Krankheitsaktivit{\"a}t zu T1 nahe, weshalb diese als zus{\"a}tzliche Kovariate in die ANCOVAs aufgenommen wurde. Krankheitsbezogene {\"A}ngste und Sorgen (PS-CEDE Gesamtwert zu T3; Krebs, Kachel \& Faller, 1998) fungierten als prim{\"a}rer Zielparameter. Zu den sekund{\"a}ren Zielkriterien geh{\"o}rten Progredienzangst und Angstbew{\"a}ltigung (PA-F-KF und PA-F; Mehnert, Herschbach, Berg, Henrich \& Koch, 2006 bzw. Dankert et al., 2003; Herschbach et al., 2005) sowie die Gesundheitskompetenzen Positive Grundhaltung, Aktive Lebensgestaltung und Erwerb von Fertigkeiten und Handlungsstrategien (heiQ; Osborne, Elsworth \& Whitfield, 2007; Schuler et al., 2013). Weitere sekund{\"a}re Zielparameter waren gesundheitsbezogene Lebensqualit{\"a}t (SF-12; Bullinger \& Kirchberger, 1998), Symptome einer Angstst{\"o}rung oder Depression (PHQ-4; Kroenke, Spitzer, Williams \& L{\"o}we, 2009; L{\"o}we et al., 2010), Wissen, der Umgang mit der CED bzw. von ihr ausgel{\"o}sten negativen Gef{\"u}hlen sowie die Zufriedenheit der Teilnehmenden mit dem Seminar. Von Interesse war außerdem, ob Geschlecht, Alter, Art, Dauer oder Aktivit{\"a}t der Erkrankung vor der Schulung einen Einfluss auf die genannten Variablen hatten und ob f{\"u}r sie differentielle Wirksamkeitseffekte bestanden. Dar{\"u}ber hinaus wurden krankheitsbezogene {\"A}ngste und Sorgen von ungeschulten Studienteilnehmern untersucht. Zwei Wochen und drei Monate nach der Schulung ließen sich im Vergleich von Experimental- und Kontrollgruppe signifikante, mittlere bis große Effekte auf krankheitsbezogene {\"A}ngste und Sorgen, Progredienzangst und deren Bew{\"a}ltigung sowie eine Positive Grundhaltung der CED gegen{\"u}ber erzielen (stets p ≤ .001). Außerdem kam es zu beiden Messzeitpunkten zu signifikanten, großen Interventionseffekten auf den Erwerb von Fertigkeiten und Handlungsstrategien im Umgang mit der Erkrankung, das Wissen um sie und den Umgang mit ihr (stets p < .001) sowie zu moderaten Effekten auf den Umgang mit CED-bedingten negativen Gef{\"u}hlen (T2: p = .001; T3: p = .008). Alle beschriebenen Effekte waren auch nach zw{\"o}lf Monaten noch stabil. F{\"u}r Aktive Lebensgestaltung, gesundheitsbezogene Lebensqualit{\"a}t sowie Angst- und Depressionssymptomatik konnten keine Schulungseffekte nachgewiesen werden. Die zus{\"a}tzliche Kontrolle f{\"u}r die Krankheitsaktivit{\"a}t zu T1 f{\"u}hrte zu keinen wesentlichen {\"A}nderungen in den Ergebnissen. Auch bei den Subgruppenanalysen hatte die Krankheitsaktivit{\"a}t keinen relevanten Einfluss auf die Wirksamkeit der Schulung. Gleiches gilt f{\"u}r Geschlecht, Alter, Art und Dauer der CED. Mit Ausnahme der Krankheitsaktivit{\"a}t deuteten dies bereits die zur Baseline durchgef{\"u}hrten t-Tests an, bei denen insgesamt nur sehr wenige signifikante, h{\"o}chstens moderate Unterschiede zwischen den einzelnen Subgruppen auftraten. Sowohl bei der formativen als auch der summativen Evaluation zeigte sich {\"u}berdies die hohe Zufriedenheit der Teilnehmenden mit der Schulung. Neben der Akzeptanz konnte außerdem die Durchf{\"u}hrbarkeit best{\"a}tigt werden. Die Auswertung der {\"A}ngste und Sorgen der Studienteilnehmenden lieferte zudem Hinweise f{\"u}r die Entwicklung und Modifikation von Interventionen f{\"u}r CED-Betroffene. Es l{\"a}sst sich festhalten, dass f{\"u}r die hier evaluierte Schulung f{\"u}r CED-Patienten ein Wirksamkeitsnachweis erbracht werden konnte und sie sehr positiv von den Teilnehmenden bewertet wurde. Sie f{\"u}hrte sowohl kurz-, mittel- als auch langfristig zu substantiellen Verbesserungen in psychischer Belastung, Selbstmanagement-F{\"a}higkeiten, der Bew{\"a}ltigung der Erkrankung sowie im Wissen und war gleichermaßen wirksam bei Betroffenen, die sich in Geschlecht, Alter, Art, Dauer oder Aktivit{\"a}t ihrer CED unterschieden.}, language = {de} } @phdthesis{Bezzenberger1991, author = {Bezzenberger, Tilman}, title = {Vorzugsaktien ohne Stimmrecht}, series = {Abhandlungen zum deutschen und europ{\"a}ischen Handels- und Wirtschaftsrecht}, journal = {Abhandlungen zum deutschen und europ{\"a}ischen Handels- und Wirtschaftsrecht}, number = {74}, publisher = {Heymanns}, address = {K{\"o}ln [u.a.]}, school = {Universit{\"a}t Potsdam}, pages = {XVI, 215}, year = {1991}, language = {de} } @phdthesis{Kruegel2014, author = {Kr{\"u}gel, Andr{\´e}}, title = {Eye movement control during reading : factors and principles of computing the word center for saccade planning}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72599}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Reading is a complex cognitive task based on the analyses of visual stimuli. Due to the physiology of the eye, only a small number of letters around the fixation position can be extracted with high visual acuity, while the visibility of words and letters outside this so-called foveal region quickly drops with increasing eccentricity. As a consequence, saccadic eye movements are needed to repeatedly shift the fovea to new words for visual word identification during reading. Moreover, even within a foveated word fixation positions near the word center are superior to other fixation positions for efficient word recognition (O'Regan, 1981; Brysbaert, Vitu, and Schroyens, 1996). Thus, most reading theories assume that readers aim specifically at word centers during reading (for a review see Reichle, Rayner, \& Pollatsek, 2003). However, saccades' landing positions within words during reading are in fact systematically modulated by the distance of the launch site from the word center (McConkie, Kerr, Reddix, \& Zola, 1988). In general, it is largely unknown how readers identify the center of upcoming target words and there is no computational model of the sensorimotor translation of the decision for a target word into spatial word center coordinates. Here we present a series of three studies which aim at advancing the current knowledge about the computation of saccade target coordinates during saccade planning in reading. Based on a large corpus analyses, we firstly identified word skipping as a further factor beyond the launch-site distance with a likewise systematic and surprisingly large effect on within-word landing positions. Most importantly, we found that the end points of saccades after skipped word are shifted two and more letters to the left as compared to one-step saccades (i.e., from word N to word N+1) with equal launch-site distances. Then we present evidence from a single saccade experiment suggesting that the word-skipping effect results from highly automatic low-level perceptual processes, which are essentially based on the localization of blank spaces between words. Finally, in the third part, we present a Bayesian model of the computation of the word center from primary sensory measurements of inter-word spaces. We demonstrate that the model simultaneously accounts for launch-site and saccade-type contingent modulations of within-word landing positions in reading. Our results show that the spatial saccade target during reading is the result of complex estimations of the word center based on incomplete sensory information, which also leads to specific systematic deviations of saccades' landing positions from the word center. Our results have important implications for current reading models and experimental reading research.}, language = {en} } @phdthesis{Jung2013, author = {Jung, Heike}, title = {F{\"u}hrungsauffassungen von Unternehmen in l{\"a}ndlichen Kleinbetrieben der westlichen Mongolei : eine Analyse der F{\"u}hrungspraxis im Kontext neocharismatischer Theorieans{\"a}tze}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72459}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Der Transformationsprozess in der Mongolei stellt besonders f{\"u}r den wirtschaftlichen Bereich eine große Herausforderung dar. Bei der Umgestaltung von der Plan-zur Marktwirtschaft nehmen dabei F{\"u}hrungskr{\"a}fte eine Schl{\"u}sselfunktion ein, da sie wesentlichen Einfluss auf den Gestaltungsprozess der sich neu orientierenden Unternehmen haben. Die Arbeit untersucht das Verh{\"a}ltnis der F{\"u}hrungskr{\"a}fte zu ihren Mitarbeitern vor dem Hintergrund neocharismatischer Theorieans{\"a}tze und kommt zum dem Schluss, dass es Hinweise auf transformationale F{\"u}hrung gibt. Dabei nehmen Gruppenprozesse, die Person der F{\"u}hrungskraft sowie traditionelle und sozialistisch sozialisierte Elemente zentrale Rollen ein. Des Weiteren gibt es Verweise auf Konzepte der Authentizit{\"a}t und der Geteilten F{\"u}hrung.}, language = {de} } @phdthesis{Bamberg2014, author = {Bamberg, Marlene}, title = {Planetary mapping tools applied to floor-fractured craters on Mars}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72104}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Planetary research is often user-based and requires considerable skill, time, and effort. Unfortunately, self-defined boundary conditions, definitions, and rules are often not documented or not easy to comprehend due to the complexity of research. This makes a comparison to other studies, or an extension of the already existing research, complicated. Comparisons are often distorted, because results rely on different, not well defined, or even unknown boundary conditions. The purpose of this research is to develop a standardized analysis method for planetary surfaces, which is adaptable to several research topics. The method provides a consistent quality of results. This also includes achieving reliable and comparable results and reducing the time and effort of conducting such studies. A standardized analysis method is provided by automated analysis tools that focus on statistical parameters. Specific key parameters and boundary conditions are defined for the tool application. The analysis relies on a database in which all key parameters are stored. These databases can be easily updated and adapted to various research questions. This increases the flexibility, reproducibility, and comparability of the research. However, the quality of the database and reliability of definitions directly influence the results. To ensure a high quality of results, the rules and definitions need to be well defined and based on previously conducted case studies. The tools then produce parameters, which are obtained by defined geostatistical techniques (measurements, calculations, classifications). The idea of an automated statistical analysis is tested to proof benefits but also potential problems of this method. In this study, I adapt automated tools for floor-fractured craters (FFCs) on Mars. These impact craters show a variety of surface features, occurring in different Martian environments, and having different fracturing origins. They provide a complex morphological and geological field of application. 433 FFCs are classified by the analysis tools due to their fracturing process. Spatial data, environmental context, and crater interior data are analyzed to distinguish between the processes involved in floor fracturing. Related geologic processes, such as glacial and fluvial activity, are too similar to be separately classified by the automated tools. Glacial and fluvial fracturing processes are merged together for the classification. The automated tools provide probability values for each origin model. To guarantee the quality and reliability of the results, classification tools need to achieve an origin probability above 50 \%. This analysis method shows that 15 \% of the FFCs are fractured by intrusive volcanism, 20 \% by tectonic activity, and 43 \% by water \& ice related processes. In total, 75 \% of the FFCs are classified to an origin type. This can be explained by a combination of origin models, superposition or erosion of key parameters, or an unknown fracturing model. Those features have to be manually analyzed in detail. Another possibility would be the improvement of key parameters and rules for the classification. This research shows that it is possible to conduct an automated statistical analysis of morphologic and geologic features based on analysis tools. Analysis tools provide additional information to the user and are therefore considered assistance systems.}, language = {en} } @phdthesis{Doering2013, author = {D{\"o}ring, Ivonne}, title = {Subjektive Krankheitskonzepte adip{\"o}ser Kinder : ihre Erfassung und ihr Einfluss auf den kindlichen Regulationsprozess}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72322}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Adipositas gilt seit einigen Jahren als eine der h{\"a}ufigsten chronischen Erkrankungen des Kindes- und Jugendalters. Welche Faktoren zu einer erfolgreichen Behandlung der Adipositas im Kindes- und Jugendalter f{\"u}hren, sind jedoch noch immer nicht ausreichend gekl{\"a}rt. Ein wichtiger - bisher jedoch weitgehend unbeachteter - Faktor, welcher m{\"o}glicherweise wegweisend f{\"u}r den Therapieverlauf sein kann, ist das subjektive Krankheitskonzept der betroffenen Kinder. Das bedeutsamste theoretische Modell, welches den Einfluss der individuellen Krankheitsvorstellungen auf den Regulationsprozess eines Menschen im Umgang mit Erkrankungen beschreibt, ist das Common Sense Model of Illness Representation (CSM) von Howard Leventhal. Ziel der vorliegenden Arbeit war es die subjektiven Krankheitskonzepte adip{\"o}ser Kinder zu erfassen und ihren Einfluss auf den Regulationsprozess zu analysieren. In einer ersten Untersuchung wurde mittels Daten von 168 adip{\"o}sen Kindern im Alter von 8 bis 12 Jahren zun{\"a}chst ein Fragebogen zur Erfassung der subjektiven Krankheitskonzepte entwickelt. Die Ergebnisse weisen darauf hin, dass der Fragebogen als reliabel und valide eingesch{\"a}tzt werden kann. Mit Hilfe dieses Fragebogens konnte nachgewiesen werden, dass adip{\"o}se Kinder Konstrukte {\"u}ber ihre Erkrankung haben, welche in eigenst{\"a}ndigen Dimensionen gespeichert werden. Die gefundenen initialen Krankheitskonzepte adip{\"o}ser Kinder ergeben ein homogenes erwartungskonformes Bild. In einer zweiten Untersuchung wurden anschließend die subjektiven Krankheitskonzepte adip{\"o}ser Kinder, die Bew{\"a}ltigungsstrategien sowie gesundheits- und krankheitsrelevante Kriteriumsvariablen untersucht. Die Befragungen erfolgten vor Beginn einer station{\"a}ren Reha (T1), am Ende der Reha (T2) sowie sechs Monate nach Reha-Ende (T3). Von 107 Kindern liegen Daten zu allen drei Messzeitpunkten vor. Es konnte ein Zusammenhang zwischen Krankheitskonzepten, Bew{\"a}ltigungsstrategien und spezifischen Kriteriumsvariablen bei adip{\"o}sen Kindern nachgewiesen werden. Die Analyse der Wirkzusammenh{\"a}nge konnte zeigen, dass die kindlichen Krankheitskonzepte - neben den indirekten Einfl{\"u}ssen {\"u}ber die Bew{\"a}ltigungsstrategien - die Kriteriumsvariablen vor allem auch direkt beeinflussen k{\"o}nnen. Der Einfluss der initialen Krankheitskonzepte adip{\"o}ser Kinder konnte hierbei sowohl im querschnittlichen als auch im l{\"a}ngsschnittlichen Design best{\"a}tigt werden. Zudem konnten vielf{\"a}ltige Einfl{\"u}sse der Ver{\"a}nderung der subjektiven Krankheitskonzepte w{\"a}hrend der Therapie gefunden werden. Die Ver{\"a}nderungen der Krankheitskonzepte wirken sowohl mittelfristig auf die individuellen Bew{\"a}ltigungsstrategien am Ende der Reha als auch l{\"a}ngerfristig auf die adipositasspezifischen Kriteriumsvariablen Gewicht, Ern{\"a}hrung, Bewegung und Lebensqualit{\"a}t. Die Befunde st{\"a}rken die Relevanz und das Potential der zielgerichteten Modifikation adaptiver bzw. maladaptiver Krankheitskonzepte innerhalb der station{\"a}ren Therapie der kindlichen Adipositas. Zudem konnte best{\"a}tigt werden, dass subjektive Krankheitskonzepte und ihre Ver{\"a}nderung innerhalb der Therapie einen relevanten Beitrag zur Vorhersage des kindlichen Therapieerfolgs {\"u}ber einen l{\"a}ngerfristigen Zeitraum leisten k{\"o}nnen.}, language = {de} } @phdthesis{Hudjetz2013, author = {Hudjetz, Annekatrin}, title = {Modelllernen im Ern{\"a}hrungskontext : m{\"u}tterlicher und v{\"a}terlicher Einfluss auf die Ern{\"a}hrung adip{\"o}ser Kinder}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72336}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Adipositas ist eine chronische Erkrankung mit erheblichen Komorbidit{\"a}ten und Folgesch{\"a}den, die bereits im Kindes- und Jugendalter weit verbreitet ist. Unterschiedliche Faktoren sind an der {\"A}tiologie dieser St{\"o}rung beteiligt. Die Ern{\"a}hrung stellt dabei eine der Haupts{\"a}ulen dar, auf welche immer wieder Bezug genommen wird. Der Einfluss der Eltern auf die kindliche Ern{\"a}hrung spielt unbestritten eine zentrale Rolle - hinsichtlich genetischer Dispositionen, aber auch als Gestalter der Lebensumwelten und Vorbilder im Ern{\"a}hrungsbereich. Die vorliegende Arbeit hat zum Ziel, {\"U}bereinstimmungen elterlicher und kindlicher Ern{\"a}hrung zu untersuchen und dabei zu pr{\"u}fen, inwiefern Prozesse des Modelllernens f{\"u}r die Zusammenh{\"a}nge verantwortlich zeichnen. Grundlage ist die sozial-kognitive Theorie Albert Banduras mit dem Fokus auf seinen Ausf{\"u}hrungen zum Beobachtungs- oder Modelllernen. Die Zusammenh{\"a}nge elterlicher und kindlicher Ern{\"a}hrung wurden anhand einer Stichprobe 7 - 13-j{\"a}hriger adip{\"o}ser Kinder und ihrer Eltern in Beziehung gesetzt zu den Bedingungen des Modelllernens, die zuvor auch in anderen Studien gefunden worden waren. Eine hohe {\"A}hnlichkeit oder gute Beziehung zwischen Modell (Mutter bzw. Vater) und Lernendem (Kind) sollte demnach moderierend auf die St{\"a}rke des Zusammenhangs wirken. Aus Banduras Ausf{\"u}hrungen zu den Phasen des Modelllernens ergibt sich zudem ein dritter Aspekt, der in das Untersuchungsmodell einbezogen wurde. Die von Bandura postulierte Aneignungsphase setzt voraus, dass das zu lernende Verhalten auch beobachtet werden kann. Aus diesem Grund sollte die Analyse von Zusammenh{\"a}ngen im Verhalten nicht losgel{\"o}st von der Zeit betrachtet werden, die Modell und Beobachter miteinander verbringen bzw. verbracht haben. Zudem wurde die Wahrnehmung eines Elternteils als Vorbild beim Kind erfragt und als Moderator aufgenommen. In die Analysen eingeschlossen wurden vollst{\"a}ndige Mutter-Vater-Kind-Triaden. Im Querschnitt der Fragebogenerhebung waren die Daten von 171 M{\"a}dchen und 176 Jungen, in einem 7 Monate darauf folgenden L{\"a}ngsschnitt insgesamt 75 Triaden (davon 38 M{\"a}dchen) enthalten. Es zeigte sich ein positiver Zusammenhang zwischen der kindlichen und m{\"u}tterlichen Ern{\"a}hrung ebenso wie zwischen der kindlichen und v{\"a}terlichen Ern{\"a}hrung. Die {\"U}bereinstimmungen zwischen Mutter und Kind waren gr{\"o}ßer als zwischen Vater und Kind. {\"U}berwiegend best{\"a}tigt werden konnten der moderierende Einfluss der Beziehungsqualit{\"a}t und der Vorbildwahrnehmung auf die Zusammenh{\"a}nge elterlicher und kindlicher gesunder Ern{\"a}hrung und der Einfluss gemeinsam verbrachter Zeit vor allem in Bezug auf Vater-Kind-Zusammenh{\"a}nge problematischer Ern{\"a}hrung. Der v{\"a}terliche Einfluss, der sowohl in Studien als auch in pr{\"a}ventiven oder therapeutischen Angeboten oft noch vernachl{\"a}ssigt wird und in vorliegender Arbeit besondere bzw. gleichberechtigte Beachtung fand, zeigte sich durch den Einbezug moderierender Variablen verst{\"a}rkt. Eine Ansprache von M{\"u}ttern und V{\"a}tern gleichermaßen ist somit unbedingtes Ziel bei der Pr{\"a}vention und Therapie kindlicher Adipositas. Auch jenseits des Adipositaskontextes sollten Eltern f{\"u}r die Bedeutung elterlicher Vorbildwirkung sensibilisiert werden, um eine gesunde Ern{\"a}hrungsweise ihrer Kinder zu f{\"o}rdern.}, language = {de} } @phdthesis{Gumienny2013, author = {Gumienny, Raja Carola}, title = {Understanding the adoption of digital whiteboard systems for collaborative design work}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72417}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {User-centered design processes are the first choice when new interactive systems or services are developed to address real customer needs and provide a good user experience. Common tools for collecting user research data, conducting brainstormings, or sketching ideas are whiteboards and sticky notes. They are ubiquitously available, and no technical or domain knowledge is necessary to use them. However, traditional pen and paper tools fall short when saving the content and sharing it with others unable to be in the same location. They are also missing further digital advantages such as searching or sorting content. Although research on digital whiteboard and sticky note applications has been conducted for over 20 years, these tools are not widely adopted in company contexts. While many research prototypes exist, they have not been used for an extended period of time in a real-world context. The goal of this thesis is to investigate what the enablers and obstacles for the adoption of digital whiteboard systems are. As an instrument for different studies, we developed the Tele-Board software system for collaborative creative work. Based on interviews, observations, and findings from former research, we tried to transfer the analog way of working to the digital world. Being a software system, Tele-Board can be used with a variety of hardware and does not depend on special devices. This feature became one of the main factors for adoption on a larger scale. In this thesis, I will present three studies on the use of Tele-Board with different user groups and foci. I will use a combination of research methods (laboratory case studies and data from field research) with the overall goal of finding out when a digital whiteboard system is used and in which cases not. Not surprisingly, the system is used and accepted if a user sees a main benefit that neither analog tools nor other applications can offer. However, I found that these perceived benefits are very different for each user and usage context. If a tool provides possibilities to use in different ways and with different equipment, the chances of its adoption by a larger group increase. Tele-Board has now been in use for over 1.5 years in a global IT company in at least five countries with a constantly growing user base. Its use, advantages, and disadvantages will be described based on 42 interviews and usage statistics from server logs. Through these insights and findings from laboratory case studies, I will present a detailed analysis of digital whiteboard use in different contexts with design implications for future systems.}, language = {en} } @phdthesis{Lotkowska2014, author = {Lotkowska, Magda Ewa}, title = {Functional analysis of MYB112 transcription factor in the model plant Arabidopsis thaliana}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72131}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Transcription factors (TFs) are ubiquitous gene expression regulators and play essential roles in almost all biological processes. This Ph.D. project is primarily focused on the functional characterisation of MYB112 - a member of the R2R3-MYB TF family from the model plant Arabidopsis thaliana. This gene was selected due to its increased expression during senescence based on previous qRT-PCR expression profiling experiments of 1880 TFs in Arabidopsis leaves at three developmental stages (15 mm leaf, 30 mm leaf and 20\% yellowing leaf). MYB112 promoter GUS fusion lines were generated to further investigate the expression pattern of MYB112. Employing transgenic approaches in combination with metabolomics and transcriptomics we demonstrate that MYB112 exerts a major role in regulation of plant flavonoid metabolism. We report enhanced and impaired anthocyanin accumulation in MYB112 overexpressors and MYB112-deficient mutants, respectively. Expression profiling reveals that MYB112 acts as a positive regulator of the transcription factor PAP1 leading to increased anthocyanin biosynthesis, and as a negative regulator of MYB12 and MYB111, which both control flavonol biosynthesis. We also identify MYB112 early responsive genes using a combination of several approaches. These include gene expression profiling (Affymetrix ATH1 micro-arrays and qRT-PCR) and transactivation assays in leaf mesophyll cell protoplasts. We show that MYB112 binds to an 8-bp DNA fragment containing the core sequence (A/T/G)(A/C)CC(A/T)(A/G/T)(A/C)(T/C). By electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation coupled to qPCR (ChIP-qPCR) we demonstrate that MYB112 binds in vitro and in vivo to MYB7 and MYB32 promoters revealing them as direct downstream target genes. MYB TFs were previously reported to play an important role in controlling flavonoid biosynthesis in plants. Many factors acting upstream of the anthocyanin biosynthesis pathway show enhanced expression levels during nitrogen limitation, or elevated sucrose content. In addition to the mentioned conditions, other environmental parameters including salinity or high light stress may trigger anthocyanin accumulation. In contrast to several other MYB TFs affecting anthocyanin biosynthesis pathway genes, MYB112 expression is not controlled by nitrogen limitation, or carbon excess, but rather is stimulated by salinity and high light stress. Thus, MYB112 constitutes a previously uncharacterised regulatory factor that modifies anthocyanin accumulation under conditions of abiotic stress.}, language = {en} } @phdthesis{Sarrar2014, author = {Sarrar, Lea}, title = {Kognitive Funktionen bei adoleszenten Patienten mit Anorexia nervosa und unipolaren Affektiven St{\"o}rungen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72439}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Anorexia nervosa und unipolare Affektive St{\"o}rungen stellen h{\"a}ufige und schwerwiegende kinder- und jugendpsychiatrische St{\"o}rungsbilder dar, deren Pathogenese bislang nicht vollst{\"a}ndig entschl{\"u}sselt ist. Verschiedene Studien zeigen bei erwachsenen Patienten gravierende Auff{\"a}lligkeiten in den kognitiven Funktionen. Dahingegen scheinen bei adoleszenten Patienten lediglich leichtere Einschr{\"a}nkungen in den kognitiven Funktionen vorzuliegen. Die Pr{\"a}valenz der Anorexia nervosa und unipolaren Affektiven St{\"o}rung ist mit Beginn der Adoleszenz deutlich erh{\"o}ht. Es ist anzunehmen, dass kognitive Dysfunktionen, die sich bereits in diesem Alter abzeichnen, den weiteren Krankheitsverlauf bis in das Erwachsenenalter, die Behandlungsergebnisse und die Prognose maßgeblich beeintr{\"a}chtigen k{\"o}nnten. Zudem ist von einem h{\"o}heren Chronifizierungsrisiko auszugehen. In der vorliegenden Arbeit wurden daher kognitive Funktionen bei adoleszenten Patientinnen mit Anorexia nervosa sowie Patienten mit unipolaren Affektiven St{\"o}rungen untersucht. Die {\"U}berpr{\"u}fung der kognitiven Funktionen bei Patientinnen mit Anorexia nervosa erfolgte vor und nach Gewichtszunahme. Weiterhin wurden zugrundeliegende biologische Mechanismen {\"u}berpr{\"u}ft. Zudem wurde die Spezifit{\"a}t kognitiver Dysfunktionen f{\"u}r beide St{\"o}rungsbilder untersucht und bei Patienten mit unipolaren Affektiven St{\"o}rungen geschlechtsbezogene Unterschiede exploriert. Insgesamt gingen 47 Patientinnen mit Anorexia nervosa (mittleres Alter 16,3 + 1,6 Jahre), 39 Patienten mit unipolaren Affektiven St{\"o}rungen (mittleres Alter 15,5 + 1,3 Jahre) sowie 78 Kontrollprobanden (mittleres Alter 16,5 + 1,3 Jahre) in die Untersuchung ein. S{\"a}mtliche Studienteilnehmer durchliefen eine neuropsychologische Testbatterie, bestehend aus Verfahren zur {\"U}berpr{\"u}fung der kognitiven Flexibilit{\"a}t sowie visuellen und psychomotorischen Verarbeitungsgeschwindigkeit. Neben einem Intelligenzscreening wurden zudem das Ausmaß der depressiven Symptomatik sowie die allgemeine psychische Belastung erfasst. Die Ergebnisse legen nahe, dass bei adoleszenten Patientinnen mit Anorexia nervosa, sowohl im akut untergewichtigen Zustand als auch nach Gewichtszunahme, lediglich milde Beeintr{\"a}chtigungen in den kognitiven Funktionen vorliegen. Im akut untergewichtigen Zustand offenbarten sich deutliche Zusammenh{\"a}nge zwischen dem appetitregulierenden Peptid Agouti-related Protein und kognitiver Flexibilit{\"a}t, nicht jedoch zwischen Agouti-related Protein und visueller oder psychomotorischer Verarbeitungsgeschwindigkeit. Bei dem Vergleich von Anorexia nervosa und unipolaren Affektiven St{\"o}rungen pr{\"a}dizierte die Zugeh{\"o}rigkeit zu der Patientengruppe Anorexia nervosa ein Risiko f{\"u}r das Vorliegen kognitiver Dysfunktionen. Es zeigte sich zudem, dass adoleszente Patienten mit unipolaren Affektiven St{\"o}rungen lediglich in der psychomotorischen Verarbeitungsgeschwindigkeit tendenziell schw{\"a}chere Leistungen offenbarten als gesunde Kontrollprobanden. Es ergab sich jedoch ein genereller geschlechtsbezogener Vorteil f{\"u}r weibliche Probanden in der visuellen und psychomotorischen Verarbeitungsgeschwindigkeit. Die vorliegenden Befunde unterstreichen die Notwendigkeit der {\"U}berpr{\"u}fung kognitiver Funktionen bei adoleszenten Patienten mit Anorexia nervosa sowie unipolaren Affektiven St{\"o}rungen in der klinischen Routinediagnostik. Die Patienten k{\"o}nnten von spezifischen Therapieprogrammen profitieren, die Beeintr{\"a}chtigungen in den kognitiven Funktionen mildern bzw. pr{\"a}ventiv behandeln.}, language = {de} } @phdthesis{Trost2014, author = {Trost, Gerda}, title = {Poly(A) Polymerase 1 (PAPS1) influences organ size and pathogen response in Arabidopsis thaliana}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72345}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Polyadenylation of pre-mRNAs is critical for efficient nuclear export, stability, and translation of the mature mRNAs, and thus for gene expression. The bulk of pre-mRNAs are processed by canonical nuclear poly(A) polymerase (PAPS). Both vertebrate and higher-plant genomes encode more than one isoform of this enzyme, and these are coexpressed in different tissues. However, in neither case is it known whether the isoforms fulfill different functions or polyadenylate distinct subsets of pre-mRNAs. This thesis shows that the three canonical nuclear PAPS isoforms in Arabidopsis are functionally specialized owing to their evolutionarily divergent C-terminal domains. A moderate loss-of-function mutant in PAPS1 leads to increase in floral organ size, whereas leaf size is reduced. A strong loss-of-function mutation causes a male gametophytic defect, whereas a weak allele leads to reduced leaf growth. By contrast, plants lacking both PAPS2 and PAPS4 function are viable with wild-type leaf growth. Polyadenylation of SMALL AUXIN UP RNA (SAUR) mRNAs depends specifically on PAPS1 function. The resulting reduction in SAUR activity in paps1 mutants contributes to their reduced leaf growth, providing a causal link between polyadenylation of specific pre-mRNAs by a particular PAPS isoform and plant growth. Additionally, opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs. The overgrowth of paps1 mutant petals is due to increased recruitment of founder cells into early organ primordia whereas the reduced leaf size is due to an ectopic pathogen response. This constitutive immune response leads to increased resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis and reflects activation of the salicylic acid-independent signalling pathway downstream of ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). Immune responses are accompanied by intracellular redox changes. Consistent with this, the redox-status of the chloroplast is altered in paps1-1 mutants. The molecular effects of the paps1-1 mutation were analysed using an RNA sequencing approach that distinguishes between long- and short tailed mRNA. The results shown here suggest the existence of an additional layer of regulation in plants and possibly vertebrate gene expression, whereby the relative activities of canonical nuclear PAPS isoforms control de novo synthesized poly(A) tail length and hence expression of specific subsets of mRNAs.}, language = {en} } @phdthesis{Arnold2014, author = {Arnold, Anne}, title = {Modeling photosynthesis and related metabolic processes : from detailed examination to consideration of the metabolic context}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72277}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Mathematical modeling of biological systems is a powerful tool to systematically investigate the functions of biological processes and their relationship with the environment. To obtain accurate and biologically interpretable predictions, a modeling framework has to be devised whose assumptions best approximate the examined scenario and which copes with the trade-off of complexity of the underlying mathematical description: with attention to detail or high coverage. Correspondingly, the system can be examined in detail on a smaller scale or in a simplified manner on a larger scale. In this thesis, the role of photosynthesis and its related biochemical processes in the context of plant metabolism was dissected by employing modeling approaches ranging from kinetic to stoichiometric models. The Calvin-Benson cycle, as primary pathway of carbon fixation in C3 plants, is the initial step for producing starch and sucrose, necessary for plant growth. Based on an integrative analysis for model ranking applied on the largest compendium of (kinetic) models for the Calvin-Benson cycle, those suitable for development of metabolic engineering strategies were identified. Driven by the question why starch rather than sucrose is the predominant transitory carbon storage in higher plants, the metabolic costs for their synthesis were examined. The incorporation of the maintenance costs for the involved enzymes provided a model-based support for the preference of starch as transitory carbon storage, by only exploiting the stoichiometry of synthesis pathways. Many photosynthetic organisms have to cope with processes which compete with carbon fixation, such as photorespiration whose impact on plant metabolism is still controversial. A systematic model-oriented review provided a detailed assessment for the role of this pathway in inhibiting the rate of carbon fixation, bridging carbon and nitrogen metabolism, shaping the C1 metabolism, and influencing redox signal transduction. The demand of understanding photosynthesis in its metabolic context calls for the examination of the related processes of the primary carbon metabolism. To this end, the Arabidopsis core model was assembled via a bottom-up approach. This large-scale model can be used to simulate photoautotrophic biomass production, as an indicator for plant growth, under so-called optimal, carbon-limiting and nitrogen-limiting growth conditions. Finally, the introduced model was employed to investigate the effects of the environment, in particular, nitrogen, carbon and energy sources, on the metabolic behavior. This resulted in a purely stoichiometry-based explanation for the experimental evidence for preferred simultaneous acquisition of nitrogen in both forms, as nitrate and ammonium, for optimal growth in various plant species. The findings presented in this thesis provide new insights into plant system's behavior, further support existing opinions for which mounting experimental evidences arise, and posit novel hypotheses for further directed large-scale experiments.}, language = {en} } @phdthesis{Serrano2014, author = {Serrano, Paloma}, title = {Methanogens from Siberian permafrost as models for life on Mars : response to simulated martian conditions and biosignature characterization}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72299}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Mars is one of the best candidates among planetary bodies for supporting life. The presence of water in the form of ice and atmospheric vapour together with the availability of biogenic elements and energy are indicators of the possibility of hosting life as we know it. The occurrence of permanently frozen ground - permafrost, is a common phenomenon on Mars and it shows multiple morphological analogies with terrestrial permafrost. Despite the extreme inhospitable conditions, highly diverse microbial communities inhabit terrestrial permafrost in large numbers. Among these are methanogenic archaea, which are anaerobic chemotrophic microorganisms that meet many of the metabolic and physiological requirements for survival on the martian subsurface. Moreover, methanogens from Siberian permafrost are extremely resistant against different types of physiological stresses as well as simulated martian thermo-physical and subsurface conditions, making them promising model organisms for potential life on Mars. The main aims of this investigation are to assess the survival of methanogenic archaea under Mars conditions, focusing on methanogens from Siberian permafrost, and to characterize their biosignatures by means of Raman spectroscopy, a powerful technology for microbial identification that will be used in the ExoMars mission. For this purpose, methanogens from Siberian permafrost and non-permafrost habitats were subjected to simulated martian desiccation by exposure to an ultra-low subfreezing temperature (-80ºC) and to Mars regolith (S-MRS and P-MRS) and atmospheric analogues. They were also exposed to different concentrations of perchlorate, a strong oxidant found in martian soils. Moreover, the biosignatures of methanogens were characterized at the single-cell level using confocal Raman microspectroscopy (CRM). The results showed survival and methane production in all methanogenic strains under simulated martian desiccation. After exposure to subfreezing temperatures, Siberian permafrost strains had a faster metabolic recovery, whereas the membranes of non-permafrost methanogens remained intact to a greater extent. The strain Methanosarcina soligelidi SMA-21 from Siberian permafrost showed significantly higher methane production rates than all other strains after the exposure to martian soil and atmospheric analogues, and all strains survived the presence of perchlorate at the concentration on Mars. Furthermore, CRM analyses revealed remarkable differences in the overall chemical composition of permafrost and non-permafrost strains of methanogens, regardless of their phylogenetic relationship. The convergence of the chemical composition in non-sister permafrost strains may be the consequence of adaptations to the environment, and could explain their greater resistance compared to the non-permafrost strains. As part of this study, Raman spectroscopy was evaluated as an analytical technique for remote detection of methanogens embedded in a mineral matrix. This thesis contributes to the understanding of the survival limits of methanogenic archaea under simulated martian conditions to further assess the hypothetical existence of life similar to methanogens on the martian subsurface. In addition, the overall chemical composition of methanogens was characterized for the first time by means of confocal Raman microspectroscopy, with potential implications for astrobiological research.}, language = {en} } @phdthesis{Lorey2014, author = {Lorey, Johannes}, title = {What's in a query : analyzing, predicting, and managing linked data access}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72312}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The term Linked Data refers to connected information sources comprising structured data about a wide range of topics and for a multitude of applications. In recent years, the conceptional and technical foundations of Linked Data have been formalized and refined. To this end, well-known technologies have been established, such as the Resource Description Framework (RDF) as a Linked Data model or the SPARQL Protocol and RDF Query Language (SPARQL) for retrieving this information. Whereas most research has been conducted in the area of generating and publishing Linked Data, this thesis presents novel approaches for improved management. In particular, we illustrate new methods for analyzing and processing SPARQL queries. Here, we present two algorithms suitable for identifying structural relationships between these queries. Both algorithms are applied to a large number of real-world requests to evaluate the performance of the approaches and the quality of their results. Based on this, we introduce different strategies enabling optimized access of Linked Data sources. We demonstrate how the presented approach facilitates effective utilization of SPARQL endpoints by prefetching results relevant for multiple subsequent requests. Furthermore, we contribute a set of metrics for determining technical characteristics of such knowledge bases. To this end, we devise practical heuristics and validate them through thorough analysis of real-world data sources. We discuss the findings and evaluate their impact on utilizing the endpoints. Moreover, we detail the adoption of a scalable infrastructure for improving Linked Data discovery and consumption. As we outline in an exemplary use case, this platform is eligible both for processing and provisioning the corresponding information.}, language = {en} } @phdthesis{Tietz2014, author = {Tietz, Marcel}, title = {Europ{\"a}isches Verwaltungsmanagement : Vergleich von Hauptst{\"a}dten neuer und alter Mitgliedsstaaten der EU am Beispiel der B{\"u}rgerdienste}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72171}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Im Rahmen der Dissertation wird die Anwendung und Wirkung von Kernelementen des New Public Management (NPM) am Beispiel der B{\"u}rgerdienste der sechs europ{\"a}ischen Hauptst{\"a}dte Berlin, Br{\"u}ssel, Kopenhagen, Madrid, Prag und Warschau analysiert. Hierbei steht der Vergleich von Hauptst{\"a}dten der MOE-Staaten mit Hauptst{\"a}dten alter EU-Mitgliedsstaaten im Vordergrund. Es wird die folgende Forschungshypothese untersucht: Die Verwaltungen in den Hauptst{\"a}dten der {\"o}stlichen Mitgliedsstaaten der EU haben in Folge der grunds{\"a}tzlichen gesellschaftlichen und politischen Umbr{\"u}che in den 1990er Jahren bedeutend mehr Kernelemente des NPM beim Neuaufbau ihrer {\"o}ffentlichen Verwaltungen eingef{\"u}hrt. Durch den folgerichtigen Aufbau kundenorientierter und moderner Verwaltungen sowie der strikten Anwendung der Kernelemente des New Public Management arbeiten die B{\"u}rgerdienste in den Hauptst{\"a}dten {\"o}stlicher EU-Mitgliedsstaaten effizienter und wirkungsvoller als vergleichbare B{\"u}rgerdienste in den Hauptst{\"a}dten westlicher EU-Mitgliedsstaaten. Zur {\"U}berpr{\"u}fung der Forschungshypothese werden die Vergleichsst{\"a}dte zun{\"a}chst den entsprechenden Rechts- und Verwaltungstraditionen (kontinentaleurop{\"a}isch deutsch, napoleonisch und skandinavisch) zugeordnet und bez{\"u}glich ihrer Ausgangslage zum Aufbau einer modernen Verwaltung (Westeurop{\"a}ische Verwaltung, Wiedervereinigungsverwaltung und Transformations-verwaltung) kategorisiert. Im Anschluss werden die institutionellen Voraussetzungen hinterfragt, was die deskriptive Darstellung der Stadt- und Verwaltungsgeschichte sowie die Untersuchung von organisatorischen Strukturen der B{\"u}rgerdienste, die Anwendung der NPM-Instrumente als auch die Innen- und Außenperspektive des NPM umfasst. Es wird festgestellt, ob und in welcher Form die B{\"u}rgerdienste der Vergleichsst{\"a}dte die Kernelemente des NPM anwenden. Im Anschluss werden die Vergleichsst{\"a}dte bez{\"u}glich der Anwendung der Kernelemente miteinander verglichen, wobei der Fokus auf dem pers{\"o}nlichen Vertriebsweg und der Kundenorientierung liegt. Der folgende Teil der Dissertation befasst sich mit dem Output der B{\"u}rgerdienste, der auf operative Resultate untersucht und verglichen wird. Hierbei stellt sich insbesondere die Frage nach den Leistungsmengen und der Produktivit{\"a}t des Outputs. Es werden aber auch die Ergebnisse von Verwaltungsprozessen untersucht, insbesondere in Bezug auf die Kundenorientierung. Hierf{\"u}r wird ein Effizienzvergleich der B{\"u}rgerdienste in den Vergleichsst{\"a}dten anhand einer relativen Effizienzmessung und der Free Disposal Hull (FDH)-Methode nach Bouckaert durchgef{\"u}hrt. Es ist eine Konzentration auf popul{\"a}re Dienstleistungen aus dem Portfolio der B{\"u}rgerdienste notwendig. Daher werden die vergleichbaren Dienstleistungen Melde-, Personalausweis-, F{\"u}hrerschein- und Reisepass-angelegenheiten unter Einbeziehung des Vollzeit{\"a}quivalents zur Berechnung der Effizienz der B{\"u}rgerdienste herangezogen. Hierf{\"u}r werden Daten aus den Jahren 2009 bis 2011 genutzt, die teilweise aus verwaltungsinternen Datenbanken stammen. Anschließend wird der Versuch unternommen, den Outcome in die Effizienzanalyse der B{\"u}rgerdienste einfließen zu lassen. In diesem Zusammenhang wird die Anwendbarkeit von verschiedenen erweiterten Best-Practice-Verfahren und auch eine Erweiterung der relativen Effizienzmessung und der FDH-Methode gepr{\"u}ft. Als Gesamtfazit der Dissertation kann festgehalten werden, dass die B{\"u}rgerdienste in den untersuchten Hauptst{\"a}dten der MOE-Staaten nicht mehr Kernelemente des NPM anwenden, als die Hauptst{\"a}dte der westlichen Mitgliedsstaaten der EU. Im Gegenteil wendet Prag deutlich weniger NPM-Instrumente als andere Vergleichsst{\"a}dte an, wohingegen Warschau zwar viele NPM-Instrumente anwendet, jedoch immer von einer westeurop{\"a}ischen Vergleichsstadt {\"u}bertroffen wird. Auch die Hypothese, dass die B{\"u}rgerdienste in den Hauptst{\"a}dten der MOE-Staaten effizienter arbeiten als vergleichbare B{\"u}rgerdienste in den Hauptst{\"a}dten westlicher EU-Mitgliedsstaaten wurde durch die Dissertation entkr{\"a}ftet. Das Gegenteil ist der Fall, da Prag und Warschau im Rahmen des Effizienzvergleichs lediglich durchschnittliche oder schlechte Performances aufweisen. Die aufgestellte Hypothese ist durch die Forschungsergebnisse widerlegt, lediglich das gute Abschneiden der Vergleichsstadt Warschau bei der Anwendungsanalyse kann einen Teil der These im gewissen Umfang best{\"a}tigen.}, language = {de} } @phdthesis{Metzner2014, author = {Metzner, Christiane}, title = {Freiwilligenmanagement als Instrument zur F{\"o}rderung B{\"u}rgerschaftlichen Engagements in Nonprofit-Organisationen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72180}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Diese Arbeit untersucht, was passiert, wenn in Non-Profit-Organisation (NPO) der Anspruch des B{\"u}rgerschaftlichen Engagements auf Praktiken des Freiwilligenmanagements trifft. Ausgangspunkt dieser Fragestellung ist eine doppelte Diagnose: Zum einen setzen NPOs aufgrund mehrerer Faktoren - u.a. Ressourcenknappheit, Wettbewerb und Nachahmungseffekten - vermehrt auf Freiwilligenmanagement. Mit dieser von der BWL inspirierten, aber f{\"u}r NPO entwickelten Personalf{\"u}hrungsmethode wollen sie mehr und bessere Freiwillige gewinnen und deren Einsatz effizienter strukturieren. Zum anderen haben sich gleichzeitig viele NPO dem Ziel des b{\"u}rgerschaftlichen Engagements verschrieben. Damit reagieren sie auf den aus Politik und Wissenschaft zu vernehmenden Anspruch, die Zivilgesellschaft m{\"o}ge die knappen Kassen der {\"o}ffentlichen Hand kompensieren und das wachsende Partizipationsbed{\"u}rfnis weiter Teile der Bev{\"o}lkerung durch eine neue Kultur der Teilhabe der B{\"u}rgerinnen und B{\"u}rger befriedigen. Bei n{\"a}herer Betrachtung zeigt sich jedoch: W{\"a}hrend Freiwilligenmanagement einer {\"o}konomischen Handlungslogik folgt, ist b{\"u}rgerschaftliches Engagement Ausdruck einer Handlungslogik der Zivilgesellschaft. Beide sind unter gegenw{\"a}rtigen Bedingungen weder theoretisch noch praktisch miteinander vereinbar. Um beide Entwicklungen miteinander zu vers{\"o}hnen, muss Freiwilligenmanagement unter dem Banner des B{\"u}rgerschaftlichen neu gedacht werden. Dieses Argument unterf{\"u}ttert die Arbeit sowohl theoretisch und empirisch. Der Theorieteil gliedert sich in drei Teile. Zun{\"a}chst wird der Begriff der NPO n{\"a}her eingegrenzt. Dazu wird die bestehende Literatur zum Dritten Sektor und Non-Profit-Organisationen zu einem operationalisierbaren Begriff von NPO kondensiert. Daran anschließend werden aktuelle Trends im Feld der NPO identifiziert, die zeigen, dass NPO tats{\"a}chlich oft von widerstreitenden Handlungslogiken gekennzeichnet sind, darunter eine {\"o}konomische und eine b{\"u}rgerschaftliche. Die beiden folgenden Kapitel untersuchen dann jeweils eine der beiden Logiken. Zun{\"a}chst wird das Leitbild des b{\"u}rgerschaftlichen Engagements als Ausdruck einer zivilgesellschaftlichen Handlungslogik n{\"a}her definiert. Dabei zeigt sich, dass dieser Begriff oft sehr unscharf verwendet wird. Daher greift die Arbeit auf die politiktheoretische Diskussion um Zivil- und B{\"u}rgergesellschaft auf und schmiedet daraus eine qualifizierte Definition von b{\"u}rgerschaftlichem Engagement, die sich maßgeblich am Ideal von gesellschaftlich-politischer Partizipation und b{\"u}rgerschaftlicher Kompetenz orientiert. Dem wird im dritten und letzten Kapitel des Theorieteils die {\"o}konomische Handlungslogik in Form der Theorie des Freiwilligenmanagements gegen{\"u}bergestellt. Bei der Darstellung zeigt sich schnell, dass dessen Grundprinzipien - anders als oft vorgebracht - mit den qualifizierten Idealen von Partizipation und Konkurrenz im Konflikt stehen. In der empirischen Analyse wird dann in den 8 Interviews den Widerspr{\"u}chen zwischen b{\"u}rgerschaftlichem Engagement und Freiwilligenmanagement in der Praxis nachgegangen. Die Ergebnisse dieser Untersuchung lassen sich in 5 Punkten zusammenfassen: 1. Freiwilligenmanagement orientiert sich erstens im wesentlichen an einer Zahl: Dem Zugewinn oder Verlust von freiwilliger Arbeit. 2. Freiwilligenmanagement installiert ein umfassendes System der Selektion von „passenden" Freiwilligen. 3. Positiv hervorzuheben ist die institutionalisierte Ansprechbarkeit, die im Rahmen von Freiwilligenmanagement in NPO Einzug erh{\"a}lt. 4. Freiwilligenmanagement ist eng mit dem Anspruch verbunden, die Arbeit der Freiwilligen zu kontrollieren. Der Eigensinn des Engagements, die Notwendigkeit von Spielr{\"a}umen, die M{\"o}glichkeit des Ausprobierens oder der Anspruch der Freiwilligen, an Entscheidungen zu partizipieren bzw. gar selbstorganisiert und -verantwortlich zu handeln, r{\"u}ckt dabei in den Hintergrund. 5. In den Interviews wird eine starke {\"O}konomisierung des Engagements sichtbar. Freiwillige werden als Ressource betrachtet, ihr Engagement als „Zeitspende" statistisch erfasst, ihre (Dienst-)Leistung monet{\"a}r bewertet. Im Zuge dessen erh{\"a}lt auch der Managerialism verst{\"a}rkt Einfluss auf die Arbeit in NPO und begr{\"u}ndet ein stark hierarchisches Verh{\"a}ltnis: W{\"a}hrend die Freiwilligenmangerin aktiv handelt, wird die freiwillig Engagierte zum Objekt von Management-Techniken. Dass dies dem Anspruch der Partizipation entgegenl{\"a}uft, ergibt sich dabei von selbst. Angesichts dieser Diagnose, dass real-existierendes Freiwilligenmanagement nicht mit dem Ideal des b{\"u}rgerschaftlichen Engagement im engeren Sinne zusammenpasst, formuliert das Fazit Vorschl{\"a}ge f{\"u}r ein b{\"u}rgerschaftlich orientiertes, engagement-sensibles Freiwilligenmanagement.
}, language = {de} } @phdthesis{Muksin2014, author = {Muksin, Umar}, title = {A fault-controlled geothermal system in Tarutung (North Sumatra, Indonesia)investigated by seismological analysis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72065}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The seismic structure (Vp, Vp/Vs, and Qp anomalies) contributes to the physical properties and the lithology of rocks and possible fluid distribution in the region. The Vp model images the geometry of the Tarutung and the Sarulla basins. Both basins have a depth of around 2.0 km. High Vp/Vs and high attenuation (low Qp) anomalies are observed along the Sarulla graben associated with a weak zone caused by volcanic activities along the graben. Low Vp/Vs and low conductivity anomalies are found in the west of the Tarutung basin. This anomaly is interpreted as dry, compact, and rigid granitic rock in the region as also found by geological observations. Low Vp, high Vp/Vs and low Qp anomalies are found at the east of the Tarutung basin which appear to be associated with the three big geothermal manifestations in Sipoholon, Hutabarat, and Panabungan area. These anomalies are connected with high Vp/Vs and low Qp anomalies below the Tarutung basin at depth of around 3 - 10 km. This suggests that these geothermal manifestations are fed by the same source of the hot fluid below the Tarutung basin. The hot fluids from below the Tarutung basin propagate to the more dilatational and more permeable zone in the northeast. Granite found in the west of the Tarutung basin could also be abundant underneath the basin at a certain depth so that it prevents the hot fluid to be transported directly to the Tarutung basin. High seismic attenuation and low Vp/Vs anomalies are found in the southwest of the Tarutung basin below the Martimbang volcano. These anomalies are associated with hot rock below the volcano without or with less amount of partial melting. There is no indication that the volcano controls the geothermal system around the Tarutung basin. The geothermal resources around the Tarutung basin is a fault-controlled system as a result of deep circulation of fluids. Outside of the basin, the seismicity delineation and the focal mechanism correlate with the shape and the characteristics of the strike-slip Sumatran fault. Within the Tarutung basin, the seismicity is distributed more broadly which coincides with the margin of the basin. An extensional duplex system in the Tarutung basin is derived from the seismicity and focal mechanism analysis which is also consistent with the geological observations. The vertical distribution of the seismicity suggests the presence of a negative flower structure within the Tarutung basin.}, language = {de} } @phdthesis{Radeff2014, author = {Radeff, Giuditta}, title = {Geohistory of the Central Anatolian Plateau southern margin (southern Turkey)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71865}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The Adana Basin of southern Turkey, situated at the SE margin of the Central Anatolian Plateau is ideally located to record Neogene topographic and tectonic changes in the easternmost Mediterranean realm. Using industry seismic reflection data we correlate 34 seismic profiles with corresponding exposed units in the Adana Basin. The time-depth conversion of the interpreted seismic profiles allows us to reconstruct the subsidence curve of the Adana Basin and to outline the occurrence of a major increase in both subsidence and sedimentation rates at 5.45 - 5.33 Ma, leading to the deposition of almost 1500 km3 of conglomerates and marls. Our provenance analysis of the conglomerates reveals that most of the sediment is derived from and north of the SE margin of the Central Anatolian Plateau. A comparison of these results with the composition of recent conglomerates and the present drainage basins indicates major changes between late Messinian and present-day source areas. We suggest that these changes in source areas result of uplift and ensuing erosion of the SE margin of the plateau. This hypothesis is supported by the comparison of the Adana Basin subsidence curve with the subsidence curve of the Mut Basin, a mainly Neogene basin located on top of the Central Anatolian Plateau southern margin, showing that the Adana Basin subsidence event is coeval with an uplift episode of the plateau southern margin. The collection of several fault measurements in the Adana region show different deformation styles for the NW and SE margins of the Adana Basin. The weakly seismic NW portion of the basin is characterized by extensional and transtensional structures cutting Neogene deposits, likely accomodating the differential uplift occurring between the basin and the SE margin of the plateau. We interpret the tectonic evolution of the southern flank of the Central Anatolian Plateau and the coeval subsidence and sedimentation in the Adana Basin to be related to deep lithospheric processes, particularly lithospheric delamination and slab break-off.}, language = {en} } @phdthesis{Busching2014, author = {Busching, Robert}, title = {Affektive und kognitive Desensibilisierung als Konsequenz von Mediengewaltkonsum : eine experimentelle Untersuchung auf Basis lerntheoretischer {\"U}berlegungen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71360}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {NutzerInnen von gewalthaltigen Medien geben einerseits oftmals zu, dass sie fiktionale, gewalthaltige Medien konsumieren, behaupten jedoch gleichzeitig, dass dies nicht ihr Verhalten außerhalb des Medienkontexts beeinflusst. Sie argumentieren, dass sie leicht zwischen Dingen, die im fiktionalen Kontext und Dingen, die in der Realit{\"a}t gelernt wurden, unterscheiden k{\"o}nnen. Im Kontrast zu diesen Aussagen zeigen Metanalysen Effektst{\"a}rken im mittleren Bereich f{\"u}r den Zusammenhang zwischen Gewaltmedienkonsum und aggressivem Verhalten. Diese Ergebnisse k{\"o}nnen nur erkl{\"a}rt werden, wenn MediennutzerInnen gewalthaltige Lernerfahrungen auch außerhalb des Medienkontexts anwenden. Ein Prozess, der Lernerfahrungen innerhalb des Medienkontexts mit dem Verhalten in der realen Welt verkn{\"u}pft, ist Desensibilisierung, die oftmals eine Reduktion des negativen Affektes gegen{\"u}ber Gewalt definiert ist. Zur Untersuchung des Desensibilisierungsprozesses wurden vier Experimente durchgef{\"u}hrt. Die erste in dieser Arbeit untersuchte Hypothese war, dass je h{\"a}ufiger Personen Gewaltmedien konsumieren, desto weniger negativen Affekt zeigen sie gegen{\"u}ber Bildern mit realer Gewalt. Jedoch wurde angenommen, dass diese Bewertung auf Darstellungen von realer Gewalt beschr{\"a}nkt ist und nicht bei Bildern ohne Gewaltbezug, die einen negativen Affekt ausl{\"o}sen, zu finden ist. Die zweite Hypothese bezog sich auf den Affekt w{\"a}hrend des Konsums von Mediengewalt. Hier wurde angenommen, dass besonders Personen, die Freude an Gewalt in den Medien empfinden weniger negativen Affekt gegen{\"u}ber realen Gewaltdarstellungen zeigen. Die letzte Hypothese besch{\"a}ftigte sich mit kognitiver Desensibilisierung und sagte vorher, dass Gewaltmedienkonsum zu einem Transfer von Reaktionen, die normalerweise gegen{\"u}ber gewalthaltigen Reizen gezeigt werden, auf urspr{\"u}nglich neutrale Reize f{\"u}hrt. Das erste Experiment (N = 57) untersuchte, ob die habituelle Nutzung von gewalthaltigen Medien den selbstberichteten Affekt (Valenz und Aktivierung) gegen{\"u}ber Darstellungen von realer Gewalt und nichtgewalthaltigen Darstellungen, die negativen Affekt ausl{\"o}sen, vorhersagt. Die habituelle Nutzung von gewalthaltigen Medien sagte weniger negative Valenz und weniger allgemeine Aktivierung gegen{\"u}ber gewalthalten und nichtgewalthaltigen Bildern vorher. Das zweite Experiment (N = 103) untersuchte auch die Beziehung zwischen habituellem Gewaltmedienkonsum und den affektiven Reaktionen gegen{\"u}ber Bildern realer Gewalt und negativen affektausl{\"o}senden Bildern. Als weiterer Pr{\"a}diktor wurde der Affekt beim Betrachten von gewalthaltigen Medien hinzugef{\"u}gt. Der Affekt gegen{\"u}ber den Bildern wurde zus{\"a}tzlich durch psychophysiologische Maße (Valenz: C: Supercilii; Aktivierung: Hautleitreaktion) erhoben. Wie zuvor sagte habitueller Gewaltmedienkonsum weniger selbstberichte Erregung und weniger negative Valenz f{\"u}r die gewalthaltigen und die negativen, gewalthaltfreien Bilder vorher. Die physiologischen Maßen replizierten dieses Ergebnis. Jedoch zeigte sich ein anderes Muster f{\"u}r den Affekt beim Konsum von Gewalt in den Medien. Personen, die Gewalt in den Medien st{\"a}rker erfreut, zeigen eine Reduktion der Responsivit{\"a}t gegen{\"u}ber Gewalt auf allen vier Maßen. Weiterhin war bei drei dieser vier Maße (selbstberichte Valenz, Aktivit{\"a}t des C. Supercilii und Hautleitreaktion) dieser Zusammenhang auf die gewalthaltigen Bilder beschr{\"a}nkt, mit keinem oder nur einem kleinen Effekt auf die negativen, aber nichtgewalthaltigen Bilder. Das dritte Experiment (N = 73) untersuchte den Affekt w{\"a}hrend die Teilnehmer ein Computerspiel spielten. Das Spiel wurde eigens f{\"u}r dieses Experiment programmiert, sodass einzelne Handlungen im Spiel mit der Aktivit{\"a}t des C. Supercilii, dem Indikator f{\"u}r negativen Affekt, in Bezug gesetzt werden konnten. Die Analyse des C. Supercilii zeigte, dass wiederholtes Durchf{\"u}hren von aggressiven Spielz{\"u}gen zu einem R{\"u}ckgang von negativen Affekt f{\"u}hrte, der die aggressiven Spielhandlungen begleitete. Der negative Affekt w{\"a}hrend gewalthaltiger Spielz{\"u}ge wiederum sagte die affektive Reaktion gegen{\"u}ber Darstellungen von gewalthaltigen Bildern vorher, nicht jedoch gegen{\"u}ber den negativen Bildern. Das vierte Experiment (N = 77) untersuchte kognitive Desensibilisierung, die die Entwicklung von Verkn{\"u}pfungen zwischen neutralen und aggressiven Kognitionen beinhaltete. Die Teilnehmer spielten einen Ego-Shooter entweder auf einem Schiff- oder einem Stadtlevel. Die Beziehung zwischen den neutralen Konstrukten (Schiff/Stadt) und den aggressiven Kognitionen wurde mit einer lexikalischen Entscheidungsaufgabe gemessen. Das Spielen im Schiff-/Stadt-Level f{\"u}hrte zu einer k{\"u}rzen Reaktionszeit f{\"u}r aggressive W{\"o}rter, wenn sie einem Schiff- bzw. Stadtprime folgten. Dies zeigte, dass die im Spiel enthaltenen neutralen Konzepte mit aggressiven Knoten verkn{\"u}pft werden. Die Ergebnisse dieser vier Experimente wurden diskutiert im Rahmen eines lerntheoretischen Ansatzes um Desensibilisierung zu konzeptualisieren.}, language = {de} } @phdthesis{Patterson2013, author = {Patterson, Clare}, title = {The role of structural and discourse-level cues during pronoun resolution}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71280}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Pronoun resolution normally takes place without conscious effort or awareness, yet the processes behind it are far from straightforward. A large number of cues and constraints have previously been recognised as playing a role in the identification and integration of potential antecedents, yet there is considerable debate over how these operate within the resolution process. The aim of this thesis is to investigate how the parser handles multiple antecedents in order to understand more about how certain information sources play a role during pronoun resolution. I consider how both structural information and information provided by the prior discourse is used during online processing. This is investigated through several eye tracking during reading experiments that are complemented by a number of offline questionnaire experiments. I begin by considering how condition B of the Binding Theory (Chomsky 1981; 1986) has been captured in pronoun processing models; some researchers have claimed that processing is faithful to syntactic constraints from the beginning of the search (e.g. Nicol and Swinney 1989), while others have claimed that potential antecedents which are ruled out on structural grounds nonetheless affect processing, because the parser must also pay attention to a potential antecedent's features (e.g. Badecker and Straub 2002). My experimental findings demonstrate that the parser is sensitive to the subtle changes in syntactic configuration which either allow or disallow pronoun reference to a local antecedent, and indicate that the parser is normally faithful to condition B at all stages of processing. Secondly, I test the Primitives of Binding hypothesis proposed by Koornneef (2008) based on work by Reuland (2001), which is a modular approach to pronoun resolution in which variable binding (a semantic relationship between pronoun and antecedent) takes place before coreference. I demonstrate that a variable-binding (VB) antecedent is not systematically considered earlier than a coreference (CR) antecedent online. I then go on to explore whether these findings could be attributed to the linear order of the antecedents, and uncover a robust recency preference both online and offline. I consider what role the factor of recency plays in pronoun resolution and how it can be reconciled with the first-mention advantage (Gernsbacher and Hargreaves 1988; Arnold 2001; Arnold et al., 2007). Finally, I investigate how aspects of the prior discourse affect pronoun resolution. Prior discourse status clearly had an effect on pronoun resolution, but an antecedent's appearance in the previous context was not always facilitative; I propose that this is due to the number of topic switches that a reader must make, leading to a lack of discourse coherence which has a detrimental effect on pronoun resolution. The sensitivity of the parser to structural cues does not entail that cue types can be easily separated into distinct sequential stages, and I therefore propose that the parser is structurally sensitive but not modular. Aspects of pronoun resolution can be captured within a parallel constraints model of pronoun resolution, however, such a model should be sensitive to the activation of potential antecedents based on discourse factors, and structural cues should be strongly weighted.}, language = {en} } @phdthesis{Winkler2013, author = {Winkler, Henning}, title = {Synthese von thermoplastisch verarbeitbaren Fetts{\"a}ure-Acylderivaten der St{\"a}rke und Proteine}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71089}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In den vergangenen Jahren wurden stetig wachsende Produktionskapazit{\"a}ten von Biokunststoffen aus nachwachsenden Rohstoffe nverzeichnet. Trotz großer Produktionskapazit{\"a}ten und einem geeigneten Eigenschaftsprofil findet St{\"a}rke nur als hydrophile, mit Weichmachern verarbeitete thermoplastische St{\"a}rke (TPS) in Form von Blends mit z. B. Polyestern Anwendung. Gleiches gilt f{\"u}r Kunststoffe auf Proteinbasis. Die vorliegende Arbeit hat die Entwicklung von Biokunststoffen auf St{\"a}rkebasis zum Ziel, welche ohne externe Weichmacher thermoplastisch verarbeitbar und hydrophob sind sowie ein mechanisches Eigenschaftsprofil aufweisen, welches ein Potenzial zur Herstellung von Materialien f{\"u}r eine Anwendung als Verpackungsmittel bietet. Um die Rohstoffbasis f{\"u}r Biokunststoffe zu erweitern, soll das erarbeitete Konzept auf zwei industriell verf{\"u}gbare Proteintypen, Zein und Molkenproteinisolat (WPI), {\"u}bertragen werden. Als geeignete Materialklasse wurden Fetts{\"a}ureester der St{\"a}rke herausgearbeitet. Zun{\"a}chst fand ein Vergleich der S{\"a}urechlorid-Veresterung und der Umesterung von Fetts{\"a}urevinylestern statt, woraus letztere als geeignetere Methode hervorging. Durch Variation der Reaktionsparameter konnte diese optimiert und auf eine Serie der Fetts{\"a}urevinylester von Butanoat bis Stearat f{\"u}r DS-Werte bis zu 2,2-2,6 angewandt werden. M{\"o}glich war somit eine systematische Studie unter Variation der veresterten Fetts{\"a}ure sowie des Substitutionsgrades (DS). S{\"a}mtliche Produkte mit einem DS ab 1,5 wiesen eine ausgpr{\"a}gte L{\"o}slichkeit in organischen L{\"o}sungsmitteln auf wodurch sowohl die Aufnahme von NMR-Spektren als auch Molmassenbestimmung mittels Gr{\"o}ßenausschlusschromatographie mit gekoppelter Mehrwinkel-Laserlichtstreuung (GPC-MALLS) m{\"o}glich waren. Durch dynamische Lichtstreuung (DLS) wurde das L{\"o}slichkeitsverhalten veranschaulicht. S{\"a}mtliche Produkte konnten zu Filmen verarbeitet werden, wobei Materialien mit DS 1,5-1,7 hohe Zugfestigkeiten (bis zu 42 MPa) und Elastizit{\"a}tsmodule (bis 1390 MPa) aufwiesen. Insbesondere St{\"a}rkehexanoat mit DS <2 sowie St{\"a}rkebutanoat mit DS >2 hatten ein mechanisches Eigenschaftsprofil, welches insbesondere in Bezug auf die Festigkeit/Steifigkeit vergleichbar mit Verpackungsmaterialien wie Polyethylen war (Zugfestigkeit: 15-32 MPa, E-Modul: 300-1300 MPa). Zugfestigkeit und Elastizit{\"a}tsmodul nahmen mit steigender Kettenl{\"a}nge der veresterten Fetts{\"a}ure ab. Ester l{\"a}ngerkettiger Fetts{\"a}uren (C16-C18) waren spr{\"o}de. {\"U}ber Weitwinkel-R{\"o}ntgenstreuung (WAXS) und Infrarotspektroskopie (ATR-FTIR) konnte der Verlauf der Festigkeiten mit einer zunehmenden Distanz der St{\"a}rke im Material begr{\"u}ndet werden. Es konnten von DS und Kettenl{\"a}nge abh{\"a}ngige Glas{\"u}berg{\"a}nge detektiert werden, die kristallinen Strukturen der langkettigen Fetts{\"a}uren zeigten einen Schmelzpeak. Die Hydrophobie der Filme wurde anhand von Kontaktwinkeln >95° gegen Wasser dargestellt. Blends mit biobasierten Polyterpenen sowie den in der Arbeit hergestellten Zein-Acylderivaten erm{\"o}glichten eine weitere Verbesserung der Zugfestigkeit bzw. des Elastizit{\"a}tsmoduls hochsubstituierter Produkte. Eine thermoplastische Verarbeitung mittels Spritzgießen war sowohl f{\"u}r Produkte mit hohem als auch mittlerem DS-Wert ohne jeglichen Zusatz von Weichmachern m{\"o}glich. Es entstanden homogene, transparente Pr{\"u}fst{\"a}be. Untersuchungen der H{\"a}rte ergaben auch hier f{\"u}r St{\"a}rkehexanoat und -butanoat mit Polyethylen vergleichbare Werte. Ausgew{\"a}hlte Produkte wurden zu Fasern nach dem Schmelzspinnverfahren verarbeitet. Hierbei wurden insbesondere f{\"u}r hochsubstituierte Derivate homogenen Fasern erstellt, welche im Vergleich zur Gießfolie signifikant h{\"o}here Zugfestigkeiten aufwiesen. St{\"a}rkeester mit mittlerem DS ließen sich ebenfalls verarbeiten. Zun{\"a}chst wurden f{\"u}r eine {\"U}bertragung des Konzeptes auf die Proteine Zein und WPI verschiedene Synthesemethoden verglichen. Die Veresterung mit S{\"a}urechloriden ergab hierbei die h{\"o}chsten Werte. Im Hinblick auf eine gute L{\"o}slichkeit in organischen L{\"o}sungsmitteln wurde f{\"u}r WPI die Veresterung mit carbonyldiimidazol (CDI)-aktivierten Fetts{\"a}uren in DMSO und f{\"u}r Zein die Veresterung mit S{\"a}u-rechloriden in Pyridin bevorzugt. Es stellte sich heraus, dass acyliertes WPI zwar hydrophob, jedoch ohne Weichmacher nicht thermoplastisch verarbeitet werden konnte. Die Erstellung von Gießfolien f{\"u}hrte zu Spr{\"o}dbruchverhalten. Unter Zugabe der biobasierten {\"O}ls{\"a}ure wurde die Anwendung von acyliertem WPI als thermoplastischer Filler z. B. in Blends mit St{\"a}rkeestern dargestellt. Im Gegensatz hierzu zeigte acyliertes Zein Glas{\"u}berg{\"a}nge <100 °C bei ausreichender Stabilit{\"a}t (150-200 °C). Zeinoleat konnte ohne Weichmacher zu einer transparenten Gießfolie verarbeitet werden. S{\"a}mtliche Derivate erwiesen sich als ausgepr{\"a}gt hydrophob. Zeinoleat konnte {\"u}ber das Schmelzspinnverfahren zu thermoplastischen Fasern verarbeitet werden.}, language = {de} } @phdthesis{Knorz2013, author = {Knorz, Marc Emanuel}, title = {Qualit{\"a}tsmanagement im organisatorischen Wandel : die Rolle von Information und Kommunikation in Qualit{\"a}tsmanagement-Systemen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71190}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {1. Teil A - Theoretische Grundlegung der Arbeit Die wissenschaftliche Arbeit beginnt mit der Darstellung der Problemstellung und der Zielsetzung der wissenschaftlichen Arbeit. Es wird deutlich aufgezeigt werden, dass sich die Lehre des Qualit{\"a}tsmanagements (QM) nur sehr unzureichend mit den sozialen Aspekten der Information \& Kommunikation (I\&K) und dem organisatorischen Wandel besch{\"a}ftigt hat. Aus diesen beiden Unterkapiteln werden die Forschungsfragen abgeleitet und der weitere Aufbau der Arbeit konstruiert. (Kapitel 1). Aufgrund der Problemstellung startet das zweite Kapitel im Rahmen der theoretischen Grundlagen mit der sozialen Systemtheorie. Die Entscheidung f{\"u}r die soziale Systemtheorie wird begr{\"u}ndet. Im Zusammenhang mit den sozialen Aspekten der I\&K werden die relevanten Erkenntnisbeitr{\"a}ge der sozialen Systemtheorien als einzelne Komponenten vorgestellt. Diese Komponenten werden dann zu einem systemtheoretischen I\&K-Modell (SEM) zusammengef{\"u}gt. (Kapitel 2). Damit die beiden Disziplinen QM und soziale Systemtheorie miteinander verbunden werden k{\"o}nnen, bedarf es im dritten Kapitel der Dissertation einer Vorstellung der daf{\"u}r notwendigen und relevanten Inhalte des QM. Im Zuge der Vorstellung der Inhalte des QM werden diese bereits mit der sozialen Systemtheorie verkn{\"u}pft, um damit aufzuzeigen, wie QMS durch I\&K existieren und operieren (Kapitel 3). Das vierte Kapitel verbindet dann die beiden Disziplinen QM und soziale Systemtheorie miteinander, wodurch ein systemtheoretisches QM-Modell (SQM) entsteht. Dieses Modell erkl{\"a}rt den Zusammenhang von QM, I\&K und organisatorischem Wandel(Kapitel 4).   2. Teil B - Empirische Untersuchung F{\"u}r die empirische Untersuchung wird in Kapitel f{\"u}nf das allgemeine Forschungsdesign hergeleitet werden. Darauf folgt die Vorstellung des Aufbaus und der Abfolge von Interviews und eines Fragebogens (Kapitel 5). Das sechste Kapitel erkl{\"a}rt die Zielsetzung, Hintergrund und Methodik der Experteninterviews mit den Qualit{\"a}tsmanagementbeauftragten (QMB) und unter-sucht die g{\"a}ngige Praxis des QM bzgl. der sozialen Aspekte der I\&K. (Kapitel 6). Das Kapitel sieben erkl{\"a}rt die Zielsetzung, Hintergrund und Methodik der Interviews mit den Unternehmen der Best-Practise (BP). (Kapitel 7). Im Kapitel acht werden die Ursache und Wirkung der sozialen Aspekte der I\&K {\"u}ber die Unternehmenskultur im Rahmen eines QMS dargestellt. (Kapitel 8). Im Kapitel neun erfolgt ein Res{\"u}mee der empirischen Untersuchungen. Die Ergebnisse der empirischen Untersuchungen werden kritisch gew{\"u}rdigt. Des Weiteren wird aufgezeigt, welcher weitere empirische Forschungsbedarf aufgedeckt wurde.(Kapitel 9). 3. Teil C - Abschluss Der Schlussteil der Arbeit beginnt mit dem zehnten Kapitel durch die Herleitung und Begr{\"u}ndung von Verbesserungspotentialen und Handlungsempfehlungen f{\"u}r die Praxis im QM.(Kapitel 10). Im elften Kapitel erfolgt die Beantwortung der Forschungsfragen und der kritischen W{\"u}rdigung der generierten Erkenntnisse.(Kapitel 11). Im zw{\"o}lften Kapitel endet die Arbeit mit einem Ausblick auf weiteren Forschungsbedarf, welcher durch das Ergebnis dieser Arbeit entstanden ist (Kapitel 12).}, language = {de} } @phdthesis{Yadavalli2014, author = {Yadavalli, Nataraja Sekhar}, title = {Advances in experimental methods to probe surface relief grating formation mechanism in photosensitive materials}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71213}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {When azobenzene-modified photosensitive polymer films are irradiated with light interference patterns, topographic variations in the film develop that follow the electric field vector distribution resulting in the formation of surface relief grating (SRG). The exact correspondence of the electric field vector orientation in interference pattern in relation to the presence of local topographic minima or maxima of SRG is in general difficult to determine. In my thesis, we have established a systematic procedure to accomplish the correlation between different interference patterns and the topography of SRG. For this, we devise a new setup combining an atomic force microscope and a two-beam interferometer (IIAFM). With this set-up, it is possible to track the topography change in-situ, while at the same time changing polarization and phase of the impinging interference pattern. To validate our results, we have compared two photosensitive materials named in short as PAZO and trimer. This is the first time that an absolute correspondence between the local distribution of electric field vectors of interference pattern and the local topography of the relief grating could be established exhaustively. In addition, using our IIAFM we found that for a certain polarization combination of two orthogonally polarized interfering beams namely SP (↕, ↔) interference pattern, the topography forms SRG with only half the period of the interference patterns. Exploiting this phenomenon we are able to fabricate surface relief structures below diffraction limit with characteristic features measuring only 140 nm, by using far field optics with a wavelength of 491 nm. We have also probed for the stresses induced during the polymer mass transport by placing an ultra-thin gold film on top (5-30 nm). During irradiation, the metal film not only deforms along with the SRG formation, but ruptures in regular and complex manner. The morphology of the cracks differs strongly depending on the electric field distribution in the interference pattern even when the magnitude and the kinetic of the strain are kept constant. This implies a complex local distribution of the opto-mechanical stress along the topography grating. The neutron reflectivity measurements of the metal/polymer interface indicate the penetration of metal layer within the polymer resulting in the formation of bonding layer that confirms the transduction of light induced stresses in the polymer layer to a metal film.}, language = {en} } @phdthesis{Schmidl2014, author = {Schmidl, Ricarda}, title = {Empirical essays on job search behavior, active labor market policies, and propensity score balancing methods}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71145}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {In Chapter 1 of the dissertation, the role of social networks is analyzed as an important determinant in the search behavior of the unemployed. Based on the hypothesis that the unemployed generate information on vacancies through their social network, search theory predicts that individuals with large social networks should experience an increased productivity of informal search, and reduce their search in formal channels. Due to the higher productivity of search, unemployed with a larger network are also expected to have a higher reservation wage than unemployed with a small network. The model-theoretic predictions are tested and confirmed empirically. It is found that the search behavior of unemployed is significantly affected by the presence of social contacts, with larger networks implying a stronger substitution away from formal search channels towards informal channels. The substitution is particularly pronounced for passive formal search methods, i.e., search methods that generate rather non-specific types of job offer information at low relative cost. We also find small but significant positive effects of an increase of the network size on the reservation wage. These results have important implications on the analysis of the job search monitoring or counseling measures that are usually targeted at formal search only. Chapter 2 of the dissertation addresses the labor market effects of vacancy information during the early stages of unemployment. The outcomes considered are the speed of exit from unemployment, the effects on the quality of employment and the short-and medium-term effects on active labor market program (ALMP) participation. It is found that vacancy information significantly increases the speed of entry into employment; at the same time the probability to participate in ALMP is significantly reduced. Whereas the long-term reduction in the ALMP arises in consequence of the earlier exit from unemployment, we also observe a short-run decrease for some labor market groups which suggest that caseworker use high and low intensity activation measures interchangeably which is clearly questionable from an efficiency point of view. For unemployed who find a job through vacancy information we observe a small negative effect on the weekly number of hours worked. In Chapter 3, the long-term effects of participation in ALMP are assessed for unemployed youth under 25 years of age. Complementary to the analysis in Chapter 2, the effects of participation in time- and cost-intensive measures of active labor market policies are examined. In particular we study the effects of job creation schemes, wage subsidies, short-and long-term training measures and measures to promote the participation in vocational training. The outcome variables of interest are the probability to be in regular employment, and participation in further education during the 60 months following program entry. The analysis shows that all programs, except job creation schemes have positive and long-term effects on the employment probability of youth. In the short-run only short-term training measures generate positive effects, as long-term training programs and wage subsidies exhibit significant locking-in'' effects. Measures to promote vocational training are found to increase the probability of attending education and training significantly, whereas all other programs have either no or a negative effect on training participation. Effect heterogeneity with respect to the pre-treatment level education shows that young people with higher pre-treatment educational levels benefit more from participation most programs. However, for longer-term wage subsidies we also find strong positive effects for young people with low initial education levels. The relative benefit of training measures is higher in West than in East Germany. In the evaluation studies of Chapters 2 and 3 semi-parametric balancing methods of Propensity Score Matching (PSM) and Inverse Probability Weighting (IPW) are used to eliminate the effects of counfounding factors that influence both the treatment participation as well as the outcome variable of interest, and to establish a causal relation between program participation and outcome differences. While PSM and IPW are intuitive and methodologically attractive as they do not require parametric assumptions, the practical implementation may become quite challenging due to their sensitivity to various data features. Given the importance of these methods in the evaluation literature, and the vast number of recent methodological contributions in this field, Chapter 4 aims to reduce the knowledge gap between the methodological and applied literature by summarizing new findings of the empirical and statistical literature and practical guidelines for future applied research. In contrast to previous publications this study does not only focus on the estimation of causal effects, but stresses that the balancing challenge can and should be discussed independent of question of causal identification of treatment effects on most empirical applications. Following a brief outline of the practical implementation steps required for PSM and IPW, these steps are presented in detail chronologically, outlining practical advice for each step. Subsequently, the topics of effect estimation, inference, sensitivity analysis and the combination with parametric estimation methods are discussed. Finally, new extensions of the methodology and avenues for future research are presented.}, language = {en} } @phdthesis{Fricke2012, author = {Fricke, Caroline}, title = {Politisch bedingte Konflikte von Jugendlichen im Bezirk Schwerin 1971 - 1989}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71090}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {„Alle Kinder m{\"u}ssen zu wertvollen Menschen erzogen werden", forderte Margot Honecker, Erziehungsminister der DDR von 1963 bis 1989. W{\"a}hrend liberale Jugendsoziologen die Jugendphase als Moratorium begreifen und damit Heranwachsenden Freir{\"a}ume zubilligen, geltende soziale Normen infrage zu stellen und selbstbestimmte Lebensentw{\"u}rfe zu erproben, ohne ihr Handeln in gleicher Weise verantworten zu m{\"u}ssen wie Erwachsene, wurden Jugendliche in der DDR danach beurteilt, inwieweit sie dem Ideal der „allseitig gebildeten sozialistischen Pers{\"o}nlichkeit" entsprachen. Nach Honeckers Ansicht w{\"a}re die freie Entfaltung des Individuums erst im Kommunismus m{\"o}glich. Individuelle Entfaltung besaß f{\"u}r sie keinen eigenen Wert. Der politische Erziehungsanspruch erstreckte sich grunds{\"a}tzlich auf alle Lebenswelten von Jugendlichen. Freir{\"a}ume zur Selbstentfaltung waren in der DDR sowohl materiell als auch ideell eng umgrenzt, ein Umstand den der bundesdeutsche Bildungssoziologe J{\"u}rgen Zinnecker als „Jugendmoratorium in kasernierter Form" bezeichnete. Dem politischen Anpassungsdruck waren Kinder und Jugendliche in besonders starkem Maße ausgesetzt. Zwar richtete sich der Erziehungsanspruch der SED grunds{\"a}tzlich auf alle B{\"u}rger, doch anders als Erwachsene hatten Kinder und Jugendliche noch keine eigenst{\"a}ndige Stellung innerhalb des sozialen und gesellschaftlichen Gef{\"u}ges gefunden und deshalb weniger M{\"o}glichkeiten, sich der politischen Einwirkung zu entziehen. Mit dem Jugendgesetz von 1974 wurde die sozialistische Pers{\"o}nlichkeit als Erziehungsziel festgelegt, dem auch die Eltern zu folgen hatten. Bildungschancen wurden schon fr{\"u}hzeitig von der Anpassung an vorgegebene Normen abh{\"a}ngig gemacht, abweichendes Verhalten konnte rigide bestraft werden und gravierende Folgen f{\"u}r den weiteren Lebensweg haben. Auch wenn die meisten Jugendlichen die Forderungen des Staates zu erf{\"u}llen schienen und ihre Verbundenheit mit der Politik der SED wann immer gefordert bezeugten, standen sie dieser Politik tats{\"a}chlich mindestens gleichg{\"u}ltig gegen{\"u}ber. Der „Widerspruch zwischen Wort und Tat" war eines der gravierenden Probleme der Herrschenden im Umgang mit Heranwachsenden. Es gab aber auch Jugendliche, die bewusst Einschr{\"a}nkungen in Kauf nahmen, um ihre Vorstellungen eines selbstbestimmten Lebens verwirklichen zu k{\"o}nnen. Schon bei geringf{\"u}giger Abweichung von ausdr{\"u}cklichen oder unausgesprochenen Vorgaben mussten sie mit erheblichen staatlichen Eingriffen in ihr pers{\"o}nliches Dasein rechnen. Die {\"a}ußerste Form der Abweichung waren Ausreiseersuchen und Fluchtversuche. Jugendliche waren unter Antragstellern und „Republikfl{\"u}chtigen" {\"u}berproportional vertreten. Die Dissertation beleuchtet das Spannungsverh{\"a}ltnis zwischen staatlich vorgegebenen Lebenswegen und eigen-sinniger Gestaltung verschiedener Lebensbereiche von Kindern und Jugendlichen f{\"u}r die Jahre der Honecker-Herrschaft zwischen 1971 bis 1989 im Bezirk Schwerin.}, language = {de} } @phdthesis{Inal2013, author = {Inal, Sahika}, title = {Responsive polymers for optical sensing applications}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70806}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes. The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy.}, language = {en} } @phdthesis{Hebig2014, author = {Hebig, Regina}, title = {Evolution of model-driven engineering settings in practice}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70761}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Nowadays, software systems are getting more and more complex. To tackle this challenge most diverse techniques, such as design patterns, service oriented architectures (SOA), software development processes, and model-driven engineering (MDE), are used to improve productivity, while time to market and quality of the products stay stable. Multiple of these techniques are used in parallel to profit from their benefits. While the use of sophisticated software development processes is standard, today, MDE is just adopted in practice. However, research has shown that the application of MDE is not always successful. It is not fully understood when advantages of MDE can be used and to what degree MDE can also be disadvantageous for productivity. Further, when combining different techniques that aim to affect the same factor (e.g. productivity) the question arises whether these techniques really complement each other or, in contrast, compensate their effects. Due to that, there is the concrete question how MDE and other techniques, such as software development process, are interrelated. Both aspects (advantages and disadvantages for productivity as well as the interrelation to other techniques) need to be understood to identify risks relating to the productivity impact of MDE. Before studying MDE's impact on productivity, it is necessary to investigate the range of validity that can be reached for the results. This includes two questions. First, there is the question whether MDE's impact on productivity is similar for all approaches of adopting MDE in practice. Second, there is the question whether MDE's impact on productivity for an approach of using MDE in practice remains stable over time. The answers for both questions are crucial for handling risks of MDE, but also for the design of future studies on MDE success. This thesis addresses these questions with the goal to support adoption of MDE in future. To enable a differentiated discussion about MDE, the term MDE setting'' is introduced. MDE setting refers to the applied technical setting, i.e. the employed manual and automated activities, artifacts, languages, and tools. An MDE setting's possible impact on productivity is studied with a focus on changeability and the interrelation to software development processes. This is done by introducing a taxonomy of changeability concerns that might be affected by an MDE setting. Further, three MDE traits are identified and it is studied for which manifestations of these MDE traits software development processes are impacted. To enable the assessment and evaluation of an MDE setting's impacts, the Software Manufacture Model language is introduced. This is a process modeling language that allows to reason about how relations between (modeling) artifacts (e.g. models or code files) change during application of manual or automated development activities. On that basis, risk analysis techniques are provided. These techniques allow identifying changeability risks and assessing the manifestations of the MDE traits (and with it an MDE setting's impact on software development processes). To address the range of validity, MDE settings from practice and their evolution histories were capture in context of this thesis. First, this data is used to show that MDE settings cover the whole spectrum concerning their impact on changeability or interrelation to software development processes. Neither it is seldom that MDE settings are neutral for processes nor is it seldom that MDE settings have impact on processes. Similarly, the impact on changeability differs relevantly. Second, a taxonomy of evolution of MDE settings is introduced. In that context it is discussed to what extent different types of changes on an MDE setting can influence this MDE setting's impact on changeability and the interrelation to processes. The category of structural evolution, which can change these characteristics of an MDE setting, is identified. The captured MDE settings from practice are used to show that structural evolution exists and is common. In addition, some examples of structural evolution steps are collected that actually led to a change in the characteristics of the respective MDE settings. Two implications are: First, the assessed diversity of MDE settings evaluates the need for the analysis techniques that shall be presented in this thesis. Second, evolution is one explanation for the diversity of MDE settings in practice. To summarize, this thesis studies the nature and evolution of MDE settings in practice. As a result support for the adoption of MDE settings is provided in form of techniques for the identification of risks relating to productivity impacts.}, language = {en} } @phdthesis{Ritz2013, author = {Ritz, Julia}, title = {Discourse-givenness of noun phrases : theoretical and computational models}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70818}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {This thesis gives formal definitions of discourse-givenness, coreference and reference, and reports on experiments with computational models of discourse-givenness of noun phrases for English and German. Definitions are based on Bach's (1987) work on reference, Kibble and van Deemter's (2000) work on coreference, and Kamp and Reyle's Discourse Representation Theory (1993). For the experiments, the following corpora with coreference annotation were used: MUC-7, OntoNotes and ARRAU for Englisch, and TueBa-D/Z for German. As for classification algorithms, they cover J48 decision trees, the rule based learner Ripper, and linear support vector machines. New features are suggested, representing the noun phrase's specificity as well as its context, which lead to a significant improvement of classification quality.}, language = {en} } @phdthesis{Schad2012, author = {Schad, Daniel}, title = {Mindless reading and eye movements : theory, experiments and computational modeling}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70822}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {It sometimes happens that we finish reading a passage of text just to realize that we have no idea what we just read. During these episodes of mindless reading our mind is elsewhere yet the eyes still move across the text. The phenomenon of mindless reading is common and seems to be widely recognized in lay psychology. However, the scientific investigation of mindless reading has long been underdeveloped. Recent progress in research on mindless reading has been based on self-report measures and on treating it as an all-or-none phenomenon (dichotomy-hypothesis). Here, we introduce the levels-of-inattention hypothesis proposing that mindless reading is graded and occurs at different levels of cognitive processing. Moreover, we introduce two new behavioral paradigms to study mindless reading at different levels in the eye-tracking laboratory. First (Chapter 2), we introduce shuffled text reading as a paradigm to approximate states of weak mindless reading experimentally and compare it to reading of normal text. Results from statistical analyses of eye movements that subjects perform in this task qualitatively support the 'mindless' hypothesis that cognitive influences on eye movements are reduced and the 'foveal load' hypothesis that the response of the zoom lens of attention to local text difficulty is enhanced when reading shuffled text. We introduce and validate an advanced version of the SWIFT model (SWIFT 3) incorporating the zoom lens of attention (Chapter 3) and use it to explain eye movements during shuffled text reading. Simulations of the SWIFT 3 model provide fully quantitative support for the 'mindless' and the 'foveal load' hypothesis. They moreover demonstrate that the zoom lens is an important concept to explain eye movements across reading and mindless reading tasks. Second (Chapter 4), we introduce the sustained attention to stimulus task (SAST) to catch episodes when external attention spontaneously lapses (i.e., attentional decoupling or mind wandering) via the overlooking of errors in the text and via signal detection analyses of error detection. Analyses of eye movements in the SAST revealed reduced influences from cognitive text processing during mindless reading. Based on these findings, we demonstrate that it is possible to predict states of mindless reading from eye movement recordings online. That cognition is not always needed to move the eyes supports autonomous mechanisms for saccade initiation. Results from analyses of error detection and eye movements provide support to our levels-of-inattention hypothesis that errors at different levels of the text assess different levels of decoupling. Analyses of pupil size in the SAST (Chapter 5) provide further support to the levels of inattention hypothesis and to the decoupling hypothesis that off-line thought is a distinct mode of cognitive functioning that demands cognitive resources and is associated with deep levels of decoupling. The present work demonstrates that the elusive phenomenon of mindless reading can be vigorously investigated in the cognitive laboratory and further incorporated in the theoretical framework of cognitive science.}, language = {en} } @phdthesis{Hoerath2012, author = {H{\"o}rath, Anna}, title = {Auf den Spuren der griechischen Mythen bei Anton Čechov in den Werken der fr{\"u}hen Schaffensperiode}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70222}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {Die Poetik des Alltags des russischen Schriftstellers Anton Čechov fasziniert bereits {\"u}ber ein Jahrhundert die Leser weltweit. Dieser Faszination liegt nicht zuletzt der griechische Mythos zugrunde, ein Kulturerbe, das die Denkweise unserer Gesellschaft tief greifend beeinflusst hat. Die antiken Gottheiten und Helden wie Apollo, Dionysos, Pythia, Narziss werden in Čechovs wenig untersuchtem Fr{\"u}hwerk zu Menschen des Alltags. Diese Projektion ist eine parodie- und travestiehafte Modifikation der mythischen Elementarstrukturen. In dieser Verschmelzung des Mythischen mit dem Allt{\"a}glichen wird Čechov zum Nachfolger insbesondere des antiken Dramatikers Epicharm. Methodisch basiert meine Analyse auf dem Begriffspaar von „Wiedergebrauchs-Rede" und „Verbrauchs-Rede" des Rhetorikers Heinrich Lausberg: Čechov erz{\"a}hlt die prominenten Mythen so wieder, dass sie zwar ihre Erhabenheit verlieren, ihre untergr{\"u}ndige Kraft jedoch beibehalten und so das Selbstbild des modernen Menschen bereichern.}, language = {de} } @phdthesis{MatienzoLeon2013, author = {Matienzo Le{\´o}n, Ena Mercedes}, title = {Ficcionalizar el referente : violencia, saber, ficcion y utop{\´i}a en El Primer Nueva Cor{\´o}nica y Buen Gobierno de Felipe Guam{\´a}n Poma de Ayala}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70758}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {La tesis doctoral „Ficcionalizar el referente. Violencia, Saber, Ficcion y Utop{\´i}a en El Primer Nueva Cor{\´o}nica y Buen Gobierno de Felipe Guam{\´a}n Poma de Ayala" tiene como objetivo explicar la violencia, el saber, la ficci{\´o}n y la utop{\´i}a en El Primer Nueva Cor{\´o}nica y Buen Gobierno. Este estudio se inicia con la Historia de la Recepci{\´o}n de El Primer Nueva Cor{\´o}nica y Buen Gobierno en el siglo XX. El criterio principal en la elaboraci{\´o}n de este registro ha sido analizar estudios destacados sobre la cr{\´o}nica peruana y que han abierto nuevos significados desde diferentes disciplinas. De esta manera la Historia de la Recepci{\´o}n de El Primer Nueva Cor{\´o}nica y Buen Gobierno se inicia a partir de un "Ensayo de Interpretaci{\´o}n" desde la arqueolog{\´i}a hasta arribar a la ciencia filol{\´o}gica que amparada por el fortalecimiento de los estudios culturales y el cuestionamiento de los "metarrelatos" en las tres {\´u}ltimas d{\´e}cadas del siglo XX desarroll{\´o} un "acto de descolonizaci{\´o}n" desde la cr{\´i}tica hist{\´o}rica y literaria. Los conceptos de violencia, saber, ficci{\´o}n y utop{\´i}a han sido constantes a lo largo del proceso de lectura y reflexi{\´o}n de la cr{\´o}nica peruana. De esta manera este estudio responde a interrogantes sobre las dimensiones y los espacios de la violencia en la cr{\´o}nica peruana. Este estudio reconoce adem{\´a}s que los relatos del fin del mundo andino y su recomposici{\´o}n corresponden a la confluencia de saberes y a su ubicidad. En El Primer Nueva Coronica y Buen Gobierno se hallan escenas de "experiencia l{\´i}mite" que puede tener un desenlace tr{\´a}gico con la desaparici{\´o}n y la muerte del autor o el abandono y perdida de esperanza de sus ideales. Sin embargo la cr{\´o}nica de Felipe Guam{\´a}n Poma de Ayala concluye por una apuesta por la vida y por tanto participa de un "saber de vida" o un "saber vivir" debido a que se halla el registro sobre la vida y de un saber que tiene la vida como objetivo central en el relato hist{\´o}rico. De esta manera la cr{\´o}nica peruana contiene una l{\´o}gica narrativa que "socava la est{\´a}tica de un destino irrevocable" y elabora una denuncia del mundo desolador con el anhelo de transformarlo. Esta escena produce fricci{\´o}n entre lo que afirma el cronista y la representaci{\´o}n ficcional del dibujo, de esta manera se halla un espacio entre lo vivido e inventado que abarcaran todo un campo de experimentaci{\´o}n que oscilan entre una dicci{\´o}n plena y la f{\´o}rmula ficcional. La tesis doctoral „Ficcionalizar el referente. Violencia, Saber, Ficcion y Utop{\´i}a en El Primer Nueva Cor{\´o}nica y Buen Gobierno de Felipe Guam{\´a}n Poma de Ayala" identific{\´o} una eclosiva fuga de la referencialidad textual de la cr{\´o}nica peruana para crear sus propias referencialidades bajo un sentido ut{\´o}pico. El testimonio dram{\´a}tico, la denuncia en voz e imagen no estar{\´a}n distanciados del elemento fant{\´a}stico y legendario propio de los primeros escritos latinoamericanos. Los artificios narrativos de El Primer Nueva Cor{\´o}nica y Buen Gobierno crea territorialidades textuales aptas para la imaginaci{\´o}n y la leyenda, cercano a lo real maravilloso. La cr{\´o}nica ind{\´i}gena fue concebida cuando se organizaba el "Buen gobierno y justicia", en un ambiente confrontacional, pero tambi{\´e}n en un mundo que era nuevo, naciente en un momento que Am{\´e}rica aparec{\´i}a como idealizaci{\´o}n del ansiado proyecto plat{\´o}nico de naci{\´o}n feliz, de un buen gobierno, una mejor naci{\´o}n, una utop{\´i}a.}, language = {mul} } @phdthesis{Bortfeld2013, author = {Bortfeld, Silvia}, title = {Analysis of Medicago truncatula transcription factors involved in the arbuscular mycorrhizal symbiosis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70664}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {For the first time the transcriptional reprogramming of distinct root cortex cells during the arbuscular mycorrhizal (AM) symbiosis was investigated by combining Laser Capture Mirodissection and Affymetrix GeneChip® Medicago genome array hybridization. The establishment of cryosections facilitated the isolation of high quality RNA in sufficient amounts from three different cortical cell types. The transcript profiles of arbuscule-containing cells (arb cells), non-arbuscule-containing cells (nac cells) of Rhizophagus irregularis inoculated Medicago truncatula roots and cortex cells of non-inoculated roots (cor) were successfully explored. The data gave new insights in the symbiosis-related cellular reorganization processes and indicated that already nac cells seem to be prepared for the upcoming fungal colonization. The mycorrhizal- and phosphate-dependent transcription of a GRAS TF family member (MtGras8) was detected in arb cells and mycorrhizal roots. MtGRAS shares a high sequence similarity to a GRAS TF suggested to be involved in the fungal colonization processes (MtRAM1). The function of MtGras8 was unraveled upon RNA interference- (RNAi-) mediated gene silencing. An AM symbiosis-dependent expression of a RNAi construct (MtPt4pro::gras8-RNAi) revealed a successful gene silencing of MtGras8 leading to a reduced arbuscule abundance and a higher proportion of deformed arbuscules in root with reduced transcript levels. Accordingly, MtGras8 might control the arbuscule development and life-time. The targeting of MtGras8 by the phosphate-dependent regulated miRNA5204* was discovered previously (Devers et al., 2011). Since miRNA5204* is known to be affected by phosphate, the posttranscriptional regulation might represent a link between phosphate signaling and arbuscule development. In this work, the posttranscriptional regulation was confirmed by mis-expression of miRNA5204* in M. truncatula roots. The miRNA-mediated gene silencing affects the MtGras8 transcript abundance only in the first two weeks of the AM symbiosis and the mis-expression lines seem to mimic the phenotype of MtGras8-RNAi lines. Additionally, MtGRAS8 seems to form heterodimers with NSP2 and RAM1, which are known to be key regulators of the fungal colonization process (Hirsch et al., 2009; Gobbato et al., 2012). These data indicate that MtGras8 and miRNA5204* are linked to the sym pathway and regulate the arbuscule development in phosphate-dependent manner.}, language = {en} } @phdthesis{Tenenboim2014, author = {Tenenboim, Yehezkel}, title = {Characterization of a Chlamydomonas protein involved in cell division and autophagy}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70650}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The contractile vacuole (CV) is an osmoregulatory organelle found exclusively in algae and protists. In addition to expelling excessive water out of the cell, it also expels ions and other metabolites and thereby contributes to the cell's metabolic homeostasis. The interest in the CV reaches beyond its immediate cellular roles. The CV's function is tightly related to basic cellular processes such as membrane dynamics and vesicle budding and fusion; several physiological processes in animals, such as synaptic neurotransmission and blood filtration in the kidney, are related to the CV's function; and several pathogens, such as the causative agents of sleeping sickness, possess CVs, which may serve as pharmacological targets. The green alga Chlamydomonas reinhardtii has two CVs. They are the smallest known CVs in nature, and they remain relatively untouched in the CV-related literature. Many genes that have been shown to be related to the CV in other organisms have close homologues in C. reinhardtii. We attempted to silence some of these genes and observe the effect on the CV. One of our genes, VMP1, caused striking, severe phenotypes when silenced. Cells exhibited defective cytokinesis and aberrant morphologies. The CV, incidentally, remained unscathed. In addition, mutant cells showed some evidence of disrupted autophagy. Several important regulators of the cell cycle as well as autophagy were found to be underexpressed in the mutant. Lipidomic analysis revealed many meaningful changes between wild-type and mutant cells, reinforcing the compromised-autophagy observation. VMP1 is a singular protein, with homologues in numerous eukaryotic organisms (aside from fungi), but usually with no relatives in each particular genome. Since its first characterization in 2002 it has been associated with several cellular processes and functions, namely autophagy, programmed cell-death, secretion, cell adhesion, and organelle biogenesis. It has been implicated in several human diseases: pancreatitis, diabetes, and several types of cancer. Our results reiterate some of the observations in VMP1's six reported homologues, but, importantly, show for the first time an involvement of this protein in cell division. The mechanisms underlying this involvement in Chlamydomonas, as well as other key aspects, such as VMP1's subcellular localization and interaction partners, still await elucidation.}, language = {en} } @phdthesis{Steinmetz2013, author = {Steinmetz, Nadine}, title = {Context-aware semantic analysis of video metadata}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70551}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Im Vergleich zu einer stichwortbasierten Suche erm{\"o}glicht die semantische Suche ein pr{\"a}ziseres und anspruchsvolleres Durchsuchen von (Web)-Dokumenten, weil durch die explizite Semantik Mehrdeutigkeiten von nat{\"u}rlicher Sprache vermieden und semantische Beziehungen in das Suchergebnis einbezogen werden k{\"o}nnen. Eine semantische, Entit{\"a}ten-basierte Suche geht von einer Anfrage mit festgelegter Bedeutung aus und liefert nur Dokumente, die mit dieser Entit{\"a}t annotiert sind als Suchergebnis. Die wichtigste Voraussetzung f{\"u}r eine Entit{\"a}ten-zentrierte Suche stellt die Annotation der Dokumente im Archiv mit Entit{\"a}ten und Kategorien dar. Textuelle Informationen werden analysiert und mit den entsprechenden Entit{\"a}ten und Kategorien versehen, um den Inhalt semantisch erschließen zu k{\"o}nnen. Eine manuelle Annotation erfordert Dom{\"a}nenwissen und ist sehr zeitaufwendig. Die semantische Annotation von Videodokumenten erfordert besondere Aufmerksamkeit, da inhaltsbasierte Metadaten von Videos aus verschiedenen Quellen stammen, verschiedene Eigenschaften und Zuverl{\"a}ssigkeiten besitzen und daher nicht wie Fließtext behandelt werden k{\"o}nnen. Die vorliegende Arbeit stellt einen semantischen Analyseprozess f{\"u}r Video-Metadaten vor. Die Eigenschaften der verschiedenen Metadatentypen werden analysiert und ein Konfidenzwert ermittelt. Dieser Wert spiegelt die Korrektheit und die wahrscheinliche Mehrdeutigkeit eines Metadatums wieder. Beginnend mit dem Metadatum mit dem h{\"o}chsten Konfidenzwert wird der Analyseprozess innerhalb eines Kontexts in absteigender Reihenfolge des Konfidenzwerts durchgef{\"u}hrt. Die bereits analysierten Metadaten dienen als Referenzpunkt f{\"u}r die weiteren Analysen. So kann eine m{\"o}glichst korrekte Analyse der heterogen strukturierten Daten eines Kontexts sichergestellt werden. Am Ende der Analyse eines Metadatums wird die f{\"u}r den Kontext relevanteste Entit{\"a}t aus einer Liste von Kandidaten identifiziert - das Metadatum wird disambiguiert. Hierf{\"u}r wurden verschiedene Disambiguierungsalgorithmen entwickelt, die Beschreibungstexte und semantische Beziehungen der Entit{\"a}tenkandidaten zum gegebenen Kontext in Betracht ziehen. Der Kontext f{\"u}r die Disambiguierung wird f{\"u}r jedes Metadatum anhand der Eigenschaften und Konfidenzwerte zusammengestellt. Der vorgestellte Analyseprozess ist an zwei Hypothesen angelehnt: Um die Analyseergebnisse verbessern zu k{\"o}nnen, sollten die Metadaten eines Kontexts in absteigender Reihenfolge ihres Konfidenzwertes verarbeitet werden und die Kontextgrenzen von Videometadaten sollten durch Segmentgrenzen definiert werden, um m{\"o}glichst Kontexte mit koh{\"a}rentem Inhalt zu erhalten. Durch ausf{\"u}hrliche Evaluationen konnten die gestellten Hypothesen best{\"a}tigt werden. Der Analyseprozess wurden gegen mehrere State-of-the-Art Methoden verglichen und erzielt verbesserte Ergebnisse in Bezug auf Recall und Precision, besonders f{\"u}r Metadaten, die aus weniger zuverl{\"a}ssigen Quellen stammen. Der Analyseprozess ist Teil eines Videoanalyse-Frameworks und wurde bereits erfolgreich in verschiedenen Projekten eingesetzt.}, language = {en} } @phdthesis{Ahmad2014, author = {Ahmad, Nadeem}, title = {People centered HMI's for deaf and functionally illiterate users}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70391}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The objective and motivation behind this research is to provide applications with easy-to-use interfaces to communities of deaf and functionally illiterate users, which enables them to work without any human assistance. Although recent years have witnessed technological advancements, the availability of technology does not ensure accessibility to information and communication technologies (ICT). Extensive use of text from menus to document contents means that deaf or functionally illiterate can not access services implemented on most computer software. Consequently, most existing computer applications pose an accessibility barrier to those who are unable to read fluently. Online technologies intended for such groups should be developed in continuous partnership with primary users and include a thorough investigation into their limitations, requirements and usability barriers. In this research, I investigated existing tools in voice, web and other multimedia technologies to identify learning gaps and explored ways to enhance the information literacy for deaf and functionally illiterate users. I worked on the development of user-centered interfaces to increase the capabilities of deaf and low literacy users by enhancing lexical resources and by evaluating several multimedia interfaces for them. The interface of the platform-independent Italian Sign Language (LIS) Dictionary has been developed to enhance the lexical resources for deaf users. The Sign Language Dictionary accepts Italian lemmas as input and provides their representation in the Italian Sign Language as output. The Sign Language dictionary has 3082 signs as set of Avatar animations in which each sign is linked to a corresponding Italian lemma. I integrated the LIS lexical resources with MultiWordNet (MWN) database to form the first LIS MultiWordNet(LMWN). LMWN contains information about lexical relations between words, semantic relations between lexical concepts (synsets), correspondences between Italian and sign language lexical concepts and semantic fields (domains). The approach enhances the deaf users' understanding of written Italian language and shows that a relatively small set of lexicon can cover a significant portion of MWN. Integration of LIS signs with MWN made it useful tool for computational linguistics and natural language processing. The rule-based translation process from written Italian text to LIS has been transformed into service-oriented system. The translation process is composed of various modules including parser, semantic interpreter, generator, and spatial allocation planner. This translation procedure has been implemented in the Java Application Building Center (jABC), which is a framework for extreme model driven design (XMDD). The XMDD approach focuses on bringing software development closer to conceptual design, so that the functionality of a software solution could be understood by someone who is unfamiliar with programming concepts. The transformation addresses the heterogeneity challenge and enhances the re-usability of the system. For enhancing the e-participation of functionally illiterate users, two detailed studies were conducted in the Republic of Rwanda. In the first study, the traditional (textual) interface was compared with the virtual character-based interactive interface. The study helped to identify usability barriers and users evaluated these interfaces according to three fundamental areas of usability, i.e. effectiveness, efficiency and satisfaction. In another study, we developed four different interfaces to analyze the usability and effects of online assistance (consistent help) for functionally illiterate users and compared different help modes including textual, vocal and virtual character on the performance of semi-literate users. In our newly designed interfaces the instructions were automatically translated in Swahili language. All the interfaces were evaluated on the basis of task accomplishment, time consumption, System Usability Scale (SUS) rating and number of times the help was acquired. The results show that the performance of semi-literate users improved significantly when using the online assistance. The dissertation thus introduces a new development approach in which virtual characters are used as additional support for barely literate or naturally challenged users. Such components enhanced the application utility by offering a variety of services like translating contents in local language, providing additional vocal information, and performing automatic translation from text to sign language. Obviously, there is no such thing as one design solution that fits for all in the underlying domain. Context sensitivity, literacy and mental abilities are key factors on which I concentrated and the results emphasize that computer interfaces must be based on a thoughtful definition of target groups, purposes and objectives.}, language = {en} } @phdthesis{Guiducci2013, author = {Guiducci, Lorenzo}, title = {Passive biomimetic actuators : the role of material architecture}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70446}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Passive plant actuators have fascinated many researchers in the field of botany and structural biology since at least one century. Up to date, the most investigated tissue types in plant and artificial passive actuators are fibre-reinforced composites (and multilayered assemblies thereof) where stiff, almost inextensible cellulose microfibrils direct the otherwise isotropic swelling of a matrix. In addition, Nature provides examples of actuating systems based on lignified, low-swelling, cellular solids enclosing a high-swelling cellulosic phase. This is the case of the Delosperma nakurense seed capsule, in which a specialized tissue promotes the reversible opening of the capsule upon wetting. This tissue has a diamond-shaped honeycomb microstructure characterized by high geometrical anisotropy: when the cellulosic phase swells inside this constraining structure, the tissue deforms up to four times in one principal direction while maintaining its original dimension in the other. Inspired by the example of the Delosoperma nakurense, in this thesis we analyze the role of architecture of 2D cellular solids as models for natural hygromorphs. To start off, we consider a simple fluid pressure acting in the cells and try to assess the influence of several architectural parameters onto their mechanical actuation. Since internal pressurization is a configurational type of load (that is the load direction is not fixed but it "follows" the structure as it deforms) it will result in the cellular structure acquiring a "spontaneous" shape. This shape is independent of the load but just depends on the architectural characteristics of the cells making up the structure itself. Whereas regular convex tiled cellular solids (such as hexagonal, triangular or square lattices) deform isotropically upon pressurization, we show through finite element simulations that by introducing anisotropic and non-convex, reentrant tiling large expansions can be achieved in each individual cell. The influence of geometrical anisotropy onto the expansion behaviour of a diamond shaped honeycomb is assessed by FEM calculations and a Born lattice approximation. We found that anisotropic expansions (eigenstrains) comparable to those observed in the keels tissue of the Delosoperma nakurense are possible. In particular these depend on the relative contributions of bending and stretching of the beams building up the honeycomb. Moreover, by varying the walls' Young modulus E and internal pressure p we found that both the eigenstrains and 2D elastic moduli scale with the ratio p/E. Therefore the potential of these pressurized structures as soft actuators is outlined. This approach was extended by considering several 2D cellular solids based on two types of non-convex cells. Each honeycomb is build as a lattice made of only one non-convex cell. Compared to usual honeycombs, these lattices have kinked walls between neighbouring cells which offers a hidden length scale allowing large directed deformations. By comparing the area expansion in all lattices, we were able to show that less convex cells are prone to achieve larger area expansions, but the direction in which the material expands is variable and depends on the local cell's connectivity. This has repercussions both at the macroscopic (lattice level) and microscopic (cells level) scales. At the macroscopic scale, these non-convex lattices can experience large anisotropic (similarly to the diamond shaped honeycomb) or perfectly isotropic principal expansions, large shearing deformations or a mixed behaviour. Moreover, lattices that at the macroscopic scale expand similarly can show quite different microscopic deformation patterns that include zig-zag motions and radical changes of the initial cell shape. Depending on the lattice architecture, the microscopic deformations of the individual cells can be equal or not, so that they can build up or mutually compensate and hence give rise to the aforementioned variety of macroscopic behaviours. Interestingly, simple geometrical arguments involving the undeformed cell shape and its local connectivity enable to predict the results of the FE simulations. Motivated by the results of the simulations, we also created experimental 3D printed models of such actuating structures. When swollen, the models undergo substantial deformation with deformation patterns qualitatively following those predicted by the simulations. This work highlights how the internal architecture of a swellable cellular solid can lead to complex shape changes which may be useful in the fields of soft robotics or morphing structures.}, language = {en} } @phdthesis{Dethloff2013, author = {Dethloff, Frederik}, title = {In vivo 13C stable isotope tracing of single leaf development in the cold}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70486}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Measuring the metabolite profile of plants can be a strong phenotyping tool, but the changes of metabolite pool sizes are often difficult to interpret, not least because metabolite pool sizes may stay constant while carbon flows are altered and vice versa. Hence, measuring the carbon allocation of metabolites enables a better understanding of the metabolic phenotype. The main challenge of such measurements is the in vivo integration of a stable or radioactive label into a plant without perturbation of the system. To follow the carbon flow of a precursor metabolite, a method is developed in this work that is based on metabolite profiling of primary metabolites measured with a mass spectrometer preceded by a gas chromatograph (Wagner et al. 2003; Erban et al. 2007; Dethloff et al. submitted). This method generates stable isotope profiling data, besides conventional metabolite profiling data. In order to allow the feeding of a 13C sucrose solution into the plant, a petiole and a hypocotyl feeding assay are developed. To enable the processing of large numbers of single leaf samples, their preparation and extraction are simplified and optimised. The metabolite profiles of primary metabolites are measured, and a simple relative calculation is done to gain information on carbon allocation from 13C sucrose. This method is tested examining single leaves of one rosette in different developmental stages, both metabolically and regarding carbon allocation from 13C sucrose. It is revealed that some metabolite pool sizes and 13C pools are tightly associated to relative leaf growth, i.e. to the developmental stage of the leaf. Fumaric acid turns out to be the most interesting candidate for further studies because pool size and 13C pool diverge considerably. In addition, the analyses are also performed on plants grown in the cold, and the initial results show a different metabolite pool size pattern across single leaves of one Arabidopsis rosette, compared to the plants grown under normal temperatures. Lastly, in situ expression of REIL genes in the cold is examined using promotor-GUS plants. Initial results suggest that single leaf metabolite profiles of reil2 differ from those of the WT.}, language = {en} } @phdthesis{Herenz2014, author = {Herenz, Peter}, title = {A study of the absorption characteristics of gaseous galaxy halos in the local Universe}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70513}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Today, it is well known that galaxies like the Milky Way consist not only of stars but also of gas and dust. The galactic halo, a sphere of gas that surrounds the stellar disk of a galaxy, is especially interesting. It provides a wealth of information about in and outflowing gaseous material towards and away from galaxies and their hierarchical evolution. For the Milky Way, the so-called high-velocity clouds (HVCs), fast moving neutral gas complexes in the halo that can be traced by absorption-line measurements, are believed to play a crucial role in the overall matter cycle in our Galaxy. Over the last decades, the properties of these halo structures and their connection to the local circumgalactic and intergalactic medium (CGM and IGM, respectively) have been investigated in great detail by many different groups. So far it remains unclear, however, to what extent the results of these studies can be transferred to other galaxies in the local Universe. In this thesis, we study the absorption properties of Galactic HVCs and compare the HVC absorption characteristics with those of intervening QSO absorption-line systems at low redshift. The goal of this project is to improve our understanding of the spatial extent and physical conditions of gaseous galaxy halos in the local Universe. In the first part of the thesis we use HST /STIS ultraviolet spectra of more than 40 extragalactic background sources to statistically analyze the absorption properties of the HVCs in the Galactic halo. We determine fundamental absorption line parameters including covering fractions of different weakly/intermediately/highly ionized metals with a particular focus on SiII and MgII. Due to the similarity in the ionization properties of SiII and MgII, we are able to estimate the contribution of HVC-like halo structures to the cross section of intervening strong MgII absorbers at z = 0. Our study implies that only the most massive HVCs would be regarded as strong MgII absorbers, if the Milky Way halo would be seen as a QSO absorption line system from an exterior vantage point. Combining the observed absorption-cross section of Galactic HVCs with the well-known number density of intervening strong MgII absorbers at z = 0, we conclude that the contribution of infalling gas clouds (i.e., HVC analogs) in the halos of Milky Way-type galaxies to the cross section of strong MgII absorbers is 34\%. This result indicates that only about one third of the strong MgII absorption can be associated with HVC analogs around other galaxies, while the majority of the strong MgII systems possibly is related to galaxy outflows and winds. The second part of this thesis focuses on the properties of intervening metal absorbers at low redshift. The analysis of the frequency and physical conditions of intervening metal systems in QSO spectra and their relation to nearby galaxies offers new insights into the typical conditions of gaseous galaxy halos. One major aspect in our study was to regard intervening metal systems as possible HVC analogs. We perform a detailed analysis of absorption line properties and line statistics for 57 metal absorbers along 78 QSO sightlines using newly-obtained ultraviolet spectra obtained with HST /COS. We find clear evidence for bimodal distribution in the HI column density in the absorbers, a trend that we interpret as sign for two different classes of absorption systems (with HVC analogs at the high-column density end). With the help of the strong transitions of SiII λ1260, SiIII λ1206, and CIII λ977 we have set up Cloudy photoionization models to estimate the local ionization conditions, gas densities, and metallicities. We find that the intervening absorption systems studied by us have, on average, similar physical conditions as Galactic HVC absorbers, providing evidence that many of them represent HVC analogs in the vicinity of other galaxies. We therefore determine typical halo sizes for SiII, SiIII, and CIII for L = 0.01L∗ and L = 0.05L∗ galaxies. Based on the covering fractions of the different ions in the Galactic halo, we find that, for example, the typical halo size for SiIII is ∼ 160 kpc for L = 0.05L∗ galaxies. We test the plausibility of this result by searching for known galaxies close to the QSO sightlines and at similar redshifts as the absorbers. We find that more than 34\% of the measured SiIII absorbers have galaxies associated with them, with the majority of the absorbers indeed being at impact parameters ρ ≤160 kpc.}, language = {en} } @phdthesis{RoggeSolti2014, author = {Rogge-Solti, Andreas}, title = {Probabilistic Estimation of Unobserved Process Events}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70426}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Organizations try to gain competitive advantages, and to increase customer satisfaction. To ensure the quality and efficiency of their business processes, they perform business process management. An important part of process management that happens on the daily operational level is process controlling. A prerequisite of controlling is process monitoring, i.e., keeping track of the performed activities in running process instances. Only by process monitoring can business analysts detect delays and react to deviations from the expected or guaranteed performance of a process instance. To enable monitoring, process events need to be collected from the process environment. When a business process is orchestrated by a process execution engine, monitoring is available for all orchestrated process activities. Many business processes, however, do not lend themselves to automatic orchestration, e.g., because of required freedom of action. This situation is often encountered in hospitals, where most business processes are manually enacted. Hence, in practice it is often inefficient or infeasible to document and monitor every process activity. Additionally, manual process execution and documentation is prone to errors, e.g., documentation of activities can be forgotten. Thus, organizations face the challenge of process events that occur, but are not observed by the monitoring environment. These unobserved process events can serve as basis for operational process decisions, even without exact knowledge of when they happened or when they will happen. An exemplary decision is whether to invest more resources to manage timely completion of a case, anticipating that the process end event will occur too late. This thesis offers means to reason about unobserved process events in a probabilistic way. We address decisive questions of process managers (e.g., "when will the case be finished?", or "when did we perform the activity that we forgot to document?") in this thesis. As main contribution, we introduce an advanced probabilistic model to business process management that is based on a stochastic variant of Petri nets. We present a holistic approach to use the model effectively along the business process lifecycle. Therefore, we provide techniques to discover such models from historical observations, to predict the termination time of processes, and to ensure quality by missing data management. We propose mechanisms to optimize configuration for monitoring and prediction, i.e., to offer guidance in selecting important activities to monitor. An implementation is provided as a proof of concept. For evaluation, we compare the accuracy of the approach with that of state-of-the-art approaches using real process data of a hospital. Additionally, we show its more general applicability in other domains by applying the approach on process data from logistics and finance.}, language = {en} } @phdthesis{Suetterlin2013, author = {S{\"u}tterlin, Martin}, title = {New inverse hydogel opals as protein responsive sensors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70179}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In this work, the development of temperature- and protein-responsive sensor materials based on biocompatible, inverse hydrogel opals (IHOs) is presented. With these materials, large biomolecules can be specifically recognised and the binding event visualised. The preparation of the IHOs was performed with a template process, for which monodisperse silica particles were vertically deposited onto glass slides as the first step. The obtained colloidal crystals with a thickness of 5 μm displayed opalescent reflections because of the uniform alignment of the colloids. As a second step, the template was embedded in a matrix consisting of biocompatible, thermoresponsive hydrogels. The comonomers were selected from the family of oligo(ethylene glycol)methacrylates. The monomer solution was injected into a polymerisation mould, which contained the colloidal crystals as a template. The space in-between the template particles was filled with the monomer solution and the hydrogel was cured via UV-polymerisation. The particles were chemically etched, which resulted in a porous inner structure. The uniform alignment of the pores and therefore the opalescent reflection were maintained, so these system were denoted as inverse hydrogel opals. A pore diameter of several hundred nanometres as well as interconnections between the pores should facilitate a diffusion of bigger (bio)molecules, which was always a challenge in the presented systems until now. The copolymer composition was chosen to result in a hydrogel collapse over 35 °C. All hydrogels showed pronounced swelling in water below the critical temperature. The incorporation of a reactive monomer with hydroxyl groups ensured a potential coupling group for the introduction of recognition units for analytes, e.g. proteins. As a test system, biotin as a recognition unit for avidin was coupled to the IHO via polymer-analogous Steglich esterification. The amount of accessible biotin was quantified with a colorimetric binding assay. When avidin was added to the biotinylated IHO, the wavelength of the opalescent reflection was significantly shifted and therefore the binding event was visualised. This effect is based on the change in swelling behaviour of the hydrogel after binding of the hydrophilic avidin, which is amplified by the thermoresponsive nature of the hydrogel. A swelling or shrinking of the pores induces a change in distance of the crystal planes, which are responsible for the colour of the reflection. With these findings, the possibility of creating sensor materials or additional biomolecules in the size range of avidin is given.}, language = {en} } @phdthesis{Neymeyer2013, author = {Neymeyer, Hanna}, title = {Annexin A1 im chronischen Nierenversagen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69670}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Die Expansion des renalen Tubulointerstitiums aufgrund einer Akkumulation zellul{\"a}rer Bestandteile und extrazellul{\"a}rer Matrix ist eine charakteristische Eigenschaft der chronischen Nierenerkrankung (CKD) und f{\"u}hrt zu einer Progression der Erkrankung in Richtung eines terminalen Nierenversagens. Die Fibroblasten Proliferation und ihre Transformation hin zum sekretorischen Myofibroblasten-Ph{\"a}notyp stellen hierbei Schl{\"u}sselereignisse dar. Signalprozesse, die zur Induktion der Myofibroblasten f{\"u}hren, werden aktiv beforscht um anti-fibrotische Therapieans{\"a}tze zu identifizieren. Das anti-inflammatorische Protein Annexin A1 und sein Rezeptor Formyl-Peptid Rezeptor 2 (FPR2) wurden in verschiedenen Organsystemen mit der Regulation von Fibroblastenaktivit{\"a}t in Verbindung gebracht, jedoch wurden ihre Expression und Funktion bei renalen fibrotischen Erkrankungen bisher nicht untersucht. Ziel der aktuellen Studie war daher die Untersuchung der renalen Annexin A1- und FPR2-Expression in einem Tiermodell des chronischen Nierenversagens, sowie die Charakterisierung der funktionellen Rolle von Annexin A1 in der Regulation des Fibroblasten Ph{\"a}notyps und ihrer Syntheseleistung. Dazu wurden neugeborene Sprague-Dawley Ratten in den ersten zwei Wochen ihres Lebens entweder mit Vehikel oder mit einem Angiotensin II Typ I Rezeptor Antagonisten behandelt und ohne weitere Intervention bis zu einem Alter von 11 Monaten (CKD Ratten) gehalten. Die Regulation und Lokalisation von Annexin A1 und FPR2 wurden mit Hilfe von Real-Time PCR und Immunhistochemie erfasst. Annexin A1- und FPR2-exprimierende Zellen wurden weiter durch Doppelimmunfluoreszenzf{\"a}rbungen charakterisiert. Gef{\"a}rbt wurde mit Antik{\"o}rpern gegen endotheliale Zellen (rat endothelial cell antigen), Makrophagen (CD 68), Fibroblasten (CD73) und Myofibroblasten (alpha-smooth muscle actin (α-sma)). Zellkulturstudien wurden an immortalisierten renalen kortikalen Fibroblasten aus Wildtyp- und Annexin A1-defizienten M{\"a}usen, sowie an etablierten humanen und murinen renalen Fibrolasten durchgef{\"u}hrt. Eine {\"U}berexpression von Annexin A1 wurde durch eine stabile Transfektion erreicht. Die Expression von Annexin A1, α-sma und Kollagen 1α1 wurde durch Real-Time PCR, Western Blot und Immuhistochemie erfasst. Die Sekretion des Annexin A1 Proteins wurde nach TCA-F{\"a}llung des Zellkultur{\"u}berstandes im Western Blot untersucht. Wie zu erwarten zeigten die CKD Ratten eine geringere Anzahl an Nephronen mit deutlicher glomerul{\"a}ren Hypertrophie. Der tubulointerstitielle Raum war durch fibrill{\"a}res Kollagen, aktivierte Fibroblasten und inflammatorische Zellen expandiert. Parallel dazu war die mRNA Expression von Annexin A1 und Transforming growth factor beta (TGF-β) signifikant erh{\"o}ht. Die Annexin A1-Lokalisation mittels Doppelimmunfluorsezenz identifizierte eine große Anzahl von CD73-positiven kortikalen Fibroblasten und eine Subpopulation von Makrophagen als Annexin A1-positiv. Die Annexin A1-Menge in Myofibroblasten und renalen Endothelien war gering. FPR2 konnte in der Mehrzahl der renalen Fibroblasten, in Myofibroblasten, in einer Subpopulation von Makrophagen und in renalen Epithelzellen nachgewiesen werden. Eine Behandlung der murinen Fibroblasten mit dem pro-fibrotischen Zytokin TGF-β f{\"u}hrte zu einem parallelen Anstieg der α-sma-, Kollagen 1α1- und Annexin A1-Biosynthese und zu einer gesteigerten Sekretion von Annexin A1. Eine {\"U}berexpression von Annexin A1 in murinen Fibroblasten reduzierte das Ausmaß der TGF-β induzierten α-sma- und Kollagen 1α1-Biosynthese. Fibroblasten aus Annexin A1-defizienten M{\"a}usen zeigten einen starken Myofibroblasten-Ph{\"a}notyp mit einer gesteigerten Expression an α-sma und Kollagen 1α1. Der Einsatz eines Peptidantagonisten des FPR2 (WRW4) resultierte in einer Stimulation der α-sma-Biosynthese, was die Vermutung nahe legte, dass Annexin A1 FPR2-vermittelt anti-fibrotische Effekte hat. Zusammenfassend zeigen diese Ergebnisse, dass renale kortikale Fibroblasten eine Hauptquelle des Annexin A1 im renalen Interstitium und einen Ansatzpunkt f{\"u}r Annexin A1-Signalwege in der Niere darstellen. Das Annexin A1/FPR2-System k{\"o}nnte daher eine wichtige Rolle in der Kontrolle des Fibroblasten Ph{\"a}notyp und der Fibroblasten Aktivit{\"a}t spielen und daher einen neuen Ansatz f{\"u}r die anti-fibrotischen pharmakologischen Strategien in der Behandlung des CKD darstellen.}, language = {de} } @phdthesis{Mondal2013, author = {Mondal, Suvendu Sekhar}, title = {Design of isostructural metal-imidazolate frameworks : application for gas storage}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69692}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The sharply rising level of atmospheric carbon dioxide resulting from anthropogenic emissions is one of the greatest environmental concerns facing our civilization today. Metal-organic frameworks (MOFs) are a new class of materials that constructed by metal-containing nodes bonded to organic bridging ligands. MOFs could serve as an ideal platform for the development of next generation CO2 capture materials owing to their large capacity for the adsorption of gases and their structural and chemical tunability. The ability to rationally select the framework components is expected to allow the affinity of the internal pore surface toward CO2 to be precisely controlled, facilitating materials properties that are optimized for the specific type of CO2 capture to be performed (post-combustion capture, precombustion capture, or oxy-fuel combustion) and potentially even for the specific power plant in which the capture system is to be installed. For this reason, significant effort has been made in recent years in improving the gas separation performance of MOFs and some studies evaluating the prospects of deploying these materials in real-world CO2 capture systems have begun to emerge. We have developed six new MOFs, denoted as IFPs (IFP-5, -6, -7, -8, -9, -10, IFP = Imidazolate Framework Potsdam) and two hydrogen-bonded molecular building block (MBB, named as 1 and 2 for Zn and Co based, respectively) have been synthesized, characterized and applied for gas storage. The structure of IFP possesses 1D hexagonal channels. Metal centre and the substituent groups of C2 position of the linker protrude into the open channels and determine their accessible diameter. Interestingly, the channel diameters (range : 0.3 to 5.2 {\AA}) for IFP structures are tuned by the metal centre (Zn, Co and Cd) and substituent of C2 position of the imidazolate linker. Moreover hydrogen bonded MBB of 1 and 2 is formed an in situ functionalization of a ligand under solvothermal condition. Two different types of channels are observed for 1 and 2. Materials contain solvent accessible void space. Solvent could be easily removed by under high vacuum. The porous framework has maintained the crystalline integrity even without solvent molecules. N2, H2, CO2 and CH4 gas sorption isotherms were performed. Gas uptake capacities are comparable with other frameworks. Gas uptake capacity is reduced when the channel diameter is narrow. For example, the channel diameter of IFP-5 (channel diameter: 3.8 {\AA}) is slightly lower than that of IFP-1 (channel diameter: 4.2 {\AA}); hence, the gas uptake capacity and Brunauer-Emmett-Teller (BET) surface area are slightly lower than IFP-1. The selectivity does not depend only on the size of the gas components (kinetic diameter: CO2 3.3 {\AA}, N2 3.6 {\AA} and CH4 3.8 ) but also on the polarizability of the surface and of the gas components. IFP-5 and-6 have the potential applications for the separation of CO2 and CH4 from N2-containing gas mixtures and CO2 and CH4 containing gas mixtures. Gas sorption isotherms of IFP-7, -8, -9, -10 exhibited hysteretic behavior due to flexible alkoxy (e.g., methoxy and ethoxy) substituents. Such phenomenon is a kind of gate effects which is rarely observed in microporous MOFs. IFP-7 (Zn-centred) has a flexible methoxy substituent. This is the first example where a flexible methoxy substituent shows the gate opening behavior in a MOF. Presence of methoxy functional group at the hexagonal channels, IFP-7 acted as molecular gate for N2 gas. Due to polar methoxy group and channel walls, wide hysteretic isotherm was observed during gas uptake. The N2 The estimated BET surface area for 1 is 471 m2 g-1 and the Langmuir surface area is 570 m2 g-1. However, such surface area is slightly higher than azolate-based hydrogen-bonded supramolecular assemblies and also comparable and higher than some hydrogen-bonded porous organic molecules.}, language = {en} }