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We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
Verwaltungsmodernisierung
(2020)
Die Modernisierung der öffentlichen Verwaltung hat sich längst zu einer Daueraufgabe entwickelt. In den Modernisierungsprozessen stehen derzeit zwei Segmente besonders im Fokus: Digitalisierung und Partizipation. Digitalisierung geht heute weit über die ursprünglich mit diesem Stichwort angesprochene Umwandlung analoger Daten in elektronische Datenformate hinaus. Die Programmatik der Digitalisierung zielt auf den möglichst umfassenden Einsatz elektronischer Informations- und Kommunikationstechniken zur Unterstützung, Beschleunigung, Rationalisierung und in Teilen auch Ersetzung von herkömmlichen Verwaltungsabläufen mit der Perspektive auf eine Transformation und Durchdringung sowohl des gesamten Verwaltungshandelns als auch der gesamten Verwaltungsorganisation. Demgegenüber meint Partizipation nach gängigem Verständnis die Beteiligung von Bürgern und anderen gesellschaftlichen Akteuren an politischen Willensbildungs- und Entscheidungsprozessen. In spezifisch administrativem Zusammenhang geht es vor allem um die Einbindung von Bürgern in Entscheidungsprozesse der Verwaltung und um die Aktivierung der Zivilgesellschaft, die Erschließung bürgerschaftlichen Engagements sowie gesellschaftlicher Ressourcen für die Erfüllung von Verwaltungsaufgaben – und dies alles mit dem Ziel einer Verbesserung der Legitimität und Qualität öffentlicher Verwaltung. Die beiden Modernisierungsansätze stehen nicht unverbunden nebeneinander. Vielmehr gehen sie nicht selten ineinander über. Beispiele dafür sind die Bereitstellung von Optionen zu elektronischer Stellung und Bearbeitung von Anträgen sowie von elektronischen Plattformen für die Bürgerpartizipation.
An diesen Themenfeldern der Verwaltungsmodernisierung setzt der Tagungsband an. Er dokumentiert den Gedankenaustausch über Digitalisierungs- und Partizipationsprozesse zwischen polnischen und deutschen Verwaltungsrechtswissenschaftlern auf einer Tagung, die im Dezember 2019 an der Universität Potsdam stattgefunden hat.
Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.
This paper evaluates the construction of the rights of human rights defenders within international law and its shortcomings in protecting women. Human rights defenders have historically been defined on the basis of their actions as defenders. However, as Marxist-feminist scholar Silvia Federici contends, women are inherently politicised and, moreover, face obstacles to political action which are invisible to and untouchable by the law. Labour rights set an example of handling such a disadvantaged political position by placing vital importance on workers’ right to association and collective action. The paper closes with the suggestion that transposing this construction of rights to women would better protect women as human rights defenders while emphasising their capacity for self-determination in their political actions.
This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers.
Depending on the biochemical and biotechnical approach, the aim of this work was to understand the mechanism of protein-glucan interactions in regulation and control of starch degradation. Although starch degradation starts with the phosphorylation process, the mechanisms by which this process is controlling and adjusting starch degradation are not yet fully understood. Phosphorylation is a major process performed by the two dikinases enzymes α-glucan, water dikinase (GWD) and phosphoglucan water dikinase (PWD). GWD and PWD enzymes phosphorylate the starch granule surface; thereby stimulate starch degradation by hydrolytic enzymes. Despite these important roles for GWD and PWD, so far the biochemical processes by which these enzymes are able to regulate and adjust the rate of phosphate incorporation into starch during the degradation process haven‘t been understood. Recently, some proteins were found associated with the starch granule. Two of these proteins are named Early Starvation Protein 1 (ESV1) and its homologue Like-Early Starvation Protein 1 (LESV). It was supposed that both are involved in the control of starch degradation, but their function has not been clearly known until now. To understand how ESV1 and LESV-glucan interactions are regulated and affect the starch breakdown, it was analyzed the influence of ESV1 and LESV proteins on the phosphorylating enzyme GWD and PWD and hydrolysing enzymes ISA, BAM, and AMY. However, the analysis determined the location of LESV and ESV1 in the chloroplast stroma of Arabidopsis. Mass spectrometry data predicted ESV1and LESV proteins as a product of the At1g42430 and At3g55760 genes with a predicted mass of ~50 kDa and ~66 kDa, respectively. The ChloroP program predicted that ESV1 lacks the chloroplast transit peptide, but it predicted the first 56 amino acids N-terminal region as a chloroplast transit peptide for LESV. Usually, the transit peptide is processed during transport of the proteins into plastids. Given that this processing is critical, two forms of each ESV1 and LESV were generated and purified, a full-length form and a truncated form that lacks the transit peptide, namely, (ESV1and tESV1) and (LESV and tLESV), respectively. Both protein forms were included in the analysis assays, but only slight differences in glucan binding and protein action between ESV1 and tESV1 were observed, while no differences in the glucan binding and effect on the GWD and PWD action were observed between LESV and tLESV. The results revealed that the presence of the N-terminal is not massively altering the action of ESV1 or LESV. Therefore, it was only used the ESV1 and tLESV forms data to explain the function of both proteins.
However, the analysis of the results revealed that LESV and ESV1 proteins bind strongly at the starch granule surface. Furthermore, not all of both proteins were released after their incubation with starches after washing the granules with 2% [w/v] SDS indicates to their binding to the deeper layers of the granule surface. Supporting of this finding comes after the binding of both proteins to starches after removing the free glucans chains from the surface by the action of ISA and BAM. Although both proteins are capable of binding to the starch structure, only LESV showed binding to amylose, while in ESV1, binding was not observed. The alteration of glucan structures at the starch granule surface is essential for the incorporation of phosphate into starch granule while the phosphorylation of starch by GWD and PWD increased after removing the free glucan chains by ISA. Furthermore, PWD showed the possibility of starch phosphorylation without prephosphorylation by GWD.
Biochemical studies on protein-glucan interactions between LESV or ESV1 with different types of starch showed a potentially important mechanism of regulating and adjusting the phosphorylation process while the binding of LESV and ESV1 leads to altering the glucan structures of starches, hence, render the effect of the action of dikinases enzymes (GWD and PWD) more able to control the rate of starch degradation. Despite the presence of ESV1 which revealed an antagonistic effect on the PWD action as the PWD action was decreased without prephosphorylation by GWD and increased after prephosphorylation by GWD (Chapter 4), PWD showed a significant reduction in its action with or without prephosphorylation by GWD in the presence of ESV1 whether separately or together with LESV (Chapter 5). However, the presence of LESV and ESV1 together revealed the same effect compared to the effect of each one alone on the phosphorylation process, therefore it is difficult to distinguish the specific function between them. However, non-interactions were detected between LESV and ESV1 or between each of them with GWD and PWD or between GWD and PWD indicating the independent work for these proteins. It was also observed that the alteration of the starch structure by LESV and ESV1 plays a role in adjusting starch degradation rates not only by affecting the dikinases but also by affecting some of the hydrolysing enzymes since it was found that the presence of LESV and ESV1leads to the reduction of the action of BAM, but does not abolish it.
Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people.
Bacteria are one of the most widespread kinds of microorganisms that play essential roles in many biological and ecological processes. Bacteria live either as independent individuals or in organized communities. At the level of single cells, interactions between bacteria, their neighbors, and the surrounding physical and chemical environment are the foundations of microbial processes. Modern microscopy imaging techniques provide attractive and promising means to study the impact of these interactions on the dynamics of bacteria. The aim of this dissertation is to deepen our understanding four fundamental bacterial processes – single-cell motility, chemotaxis, bacterial interactions with environmental constraints, and their communication with neighbors – through a live cell imaging technique. By exploring these processes, we expanded our knowledge on so far unexplained mechanisms of bacterial interactions.
Firstly, we studied the motility of the soil bacterium Pseudomonas putida (P. putida), which swims through flagella propulsion, and has a complex, multi-mode swimming tactic. It was recently reported that P. putida exhibits several distinct swimming modes – the flagella can push and pull the cell body or wrap around it. Using a new combined phase-contrast and fluorescence imaging set-up, the swimming mode (push, pull, or wrapped) of each run phase was automatically recorded, which provided the full swimming statistics of the multi-mode swimmer. Furthermore, the investigation of cell interactions with a solid boundary illustrated an asymmetry for the different swimming modes; in contrast to the push and pull modes, the curvature of runs in wrapped mode was not affected by the solid boundary. This finding suggested that having a multi-mode swimming strategy may provide further versatility to react to environmental constraints.
Then we determined how P. putida navigates toward chemoattractants, i.e. its chemotaxis strategies. We found that individual run modes show distinct chemotactic responses in nutrition gradients. In particular, P. putida cells exhibited an asymmetry in their chemotactic responsiveness; the wrapped mode (slow swimming mode) was affected by the chemoattractant, whereas the push mode (fast swimming mode) was not. These results can be seen as a starting point to understand more complex chemotaxis strategies of multi-mode swimmers going beyond the well-known paradigm of Escherichia coli, that exhibits only one swimming mode.
Finally we considered the cell dynamics in a dense population. Besides physical interactions with their neighbors, cells communicate their activities and orchestrate their population behaviors via quorum-sensing. Molecules that are secreted to the surrounding by the bacterial cells, act as signals and regulate the cell population behaviour. We studied P. putida’s motility in a dense population by exposing the cells to environments with different concentrations of chemical signals. We found that higher amounts of chemical signals in the surrounding influenced the single-cell behaviourr, suggesting that cell-cell communications may also affect the flagellar dynamics.
In summary, this dissertation studies the dynamics of a bacterium with a multi-mode swimming tactic and how it is affected by the surrounding environment using microscopy imaging. The detailed description of the bacterial motility in fundamental bacterial processes can provide new insights into the ecology of microorganisms.
Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats.
In this thesis, I examine different A-bar movement dependencies in Igbo, a Benue-Congo language spoken in southern Nigeria. Movement dependencies are found in constructions where an element is moved to the left edge of the clause to express information-structural categories such as in questions, relativization and focus. I show that these constructions in Igbo are very uniform from a syntactic point of view. The constructions are built on two basic fronting operations: relativization and focus movement, and are biclausal. I further investigate several morphophonological effects that are found in these A-bar constructions. I propose that these effects are reflexes of movement that are triggered when an element is moved overtly in relativization or focus. This proposal helps to explain the tone patterns that have previously been assumed to be a property of relative clauses. The thesis adds to the growing body of tonal reflexes of A-bar movement reported for a few African languages. The thesis also provides an insight into the complementizer domain (C-domain) of Igbo.
Under an ecological speciation scenario, the radiation of African weakly electric fish (genus Campylomormyrus) is caused by an adaptation to different food sources, associated with diversification of the electric organ discharge (EOD). This study experimentally investigates a phenotype-environment correlation to further support this scenario. Our behavioural experiments showed that three sympatric Campylomormyrus species with significantly divergent snout morphology differentially react to variation in substrate structure. While the short snout species (C. tamandua) exhibits preference to sandy substrate, the long snout species (C. rhynchophorus) significantly prefers a stone substrate for feeding. A third species with intermediate snout size (C. compressirostris) does not exhibit any substrate preference. This preference is matched with the observation that long-snouted specimens probe deeper into the stone substrate, presumably enabling them to reach prey more distant to the substrate surface. These findings suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to specific microhabitats, i.e., substrate structures where these fish forage. Whether the parallel divergence in EOD is functionally related to this adaptation or solely serves as a prezygotic isolation mechanism remains to be elucidated.
Die vorliegende Arbeit untersucht Urlaubsfotografien bei Facebook und beschreibt, welche sozio-technischen Medienpraktiken sich innerhalb der Social-Media Plattform über die Fotografien vollziehen. Fotografische Praktiken sind durch aktive Handlungen und soziale Gebrauchsweisen bestimmt. Urlaubsfotografien tragen zum Beispiel zur Strukturierung von Reiserouten und Vorstellungen bei, indem genrespezifische Motive und Rahmungen mit Hilfe von Medien reproduziert und wiederholt werden. Praktiken des Zeigens, Teilens und Kommunizierens werden durch Social Plug-Ins (Like/Share Buttons) und Tagging-Funktionen auch in die Benutzeroberflächen von Facebook integriert. Dadurch werden Nutzer*innen Aktivitäten und technische Prozesse miteinander verbunden. Am Beispiel der automatischen Generierung von Urlaubsfotografien auf Geotagseiten wird gezeigt, dass Social-Tagging zur Entstehung und Aushandlung geographischer Räume und Ortsvorstellungen beiträgt. Mithilfe technischer Strukturierungen von Fotografien auf Taggingseiten werden genrespezifische Motive, fotografische Trends und Ästhetiken besonders sichtbar. Allerdings wird ihre Visualisierung auch durch algorithmische Priorisierung einzelner Inhalte mitbestimmt. Dadurch werden Urlaubsfotografien für ein fotografisches Profiling genutzt, da sie das algorithmische Erfassen und Auswerten von Nutzer*innen-Informationen ermöglichen. Die Arbeit zeigt, dass der Einsatz von Bilderkennungsverfahren und fotografischen Datenanalysen zu einer optimierten Informationsgewinnung und zu einer Standardisierung von Fotografien beiträgt.
Numerous studies investigate which sanctioning institutions prevent cartel formation but little is known as to how these sanctions work. We contribute to understanding the inner workings of cartels by studying experimentally the effect of sanctioning institutions on firms’ communication. Using machine learning to organize the chat communication into topics, we find that firms are significantly less likely to communicate explicitly about price fixing when sanctioning institutions are present. At the same time, average prices are lower when communication is less explicit. A mediation analysis suggests that sanctions are effective in hindering cartel formation not only because they introduce a risk of being fined but also by reducing the prevalence of explicit price communication.
Potato is the 4th most important food crop in the world. Especially in tropical and sub-tropical potato production, drought is a yield limiting factor. Potato is sensitive to water stress. Potato yield loss under water stress could be reduced by using tolerant varieties and adjusted agronomic practices. Direct selection for yield under water-stressed conditions requires long selection cycles. Thus, identification of markers for marker-assisted selection may speed up breeding. The objective of this thesis is to identify morphological markers for drought tolerance by continuously monitoring plant growth and canopy temperature with an automatic phenotyping system.
The phenotyping was performed in drought-stress experiments that were conducted in population A with 64 genotypes and population B with 21 genotypes in the screenhouse in 2015 and 2016 (population A) and in 2017 and 2018 (population B). Drought tolerance was quantified as deviation of the relative tuber starch yield from the experimental median (DRYM) and parent median (DRYMp). Relative tuber starch yield is starch yield under drought stress relative to the average starch yield of the respective cultivar under control conditions in the same experiment. The specific DRYM value was calculated based on the yield data of the same experiment or the global DRYM that was calculated from yield data derived from data combined over yeas of respective population or across multiple experiments including VALDIS and TROST experiments (2011-2016).
Analysis of variance found a significant effect of genotype on DRYM indicating that the tolerance variation required for marker identification was given in both populations.
Canopy growth was monitored continuously six times a day over five to ten weeks by a laser scanner system and yielded information on leaf area, plant height and leaf angle for population A and additionally on leaf inclination and light penetration depth for population B. Canopy temperature was measured 48 times a day over six to seven weeks by infrared thermometry in population B. From the continuous IRT surface temperature data set, the canopy temperature for each plant was selected by matching the time stamp of the IRT data with laser scanner data.
Mean, maximum, range and growth rate values were calculated from continuous laser scanner measurements of respective canopy parameters. Among the canopy parameters, the maximum and mean values in long-term stress conditions showed better correlation with DRYM values calculated in the same experiment than growth rate and diurnal range values. Therefore, drought tolerance index prediction was done from maximum and mean values of canopy parameters.
The tolerance index in specific experiment condition was linearly predicted by simple regression model from different single canopy parameters under long-term stress condition in population A (2016) and population B (2017 and 2018). Among the canopy parameters maximum light penetration depth (2017), mean leaf angle (2017, 2018, and 2016), mean leaf inclination or mean canopy temperature depression (2017 and 2018), maximum plant height (2017) were selected as tolerance predictors. However, no single parameters were sufficient to predict DRYM. Therefore, several independent parameters were integrated in a multiple regression model.
In multiple regression model, specific experiment DRYM values in population A was predicted from mean leaf angle (2016). In population B, specific tolerance could be predicted from maximum light penetration depth and mean leaf inclination (2017) and mean leaf inclination (2018) or mean canopy temperature depression and mean leaf angle (2018).
In data combined over season of population A, the multiple linear regression model selected maximum plant height and mean leaf angle as tolerance predictor. In Population B, mean leaf inclination was selected as tolerance predictor. However, in population A, the variation explained by the final model was too low.
Furthermore, the average tolerances respective to parent median (2011-2018) across FGH plants or all plants (FGH and field) were predicted from maximum plant height (population A) and maximum plant height and mean leaf inclination (population B). Altogether, canopy parameters could be used as markers for drought tolerance. Therefore, water stress breeding in potato could be speed up through using leaf inclination, light penetration depth, plant height and canopy temperature depression as markers for drought tolerance, especially in long-term stress conditions.
This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r²) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season.
During a dark night, it is possible to observe thousands of stars by eye. All these stars are located within the Milky Way, our home. Not all stars are the same, they can have different sizes, masses, temperatures and ages. Heavy stars do not live long (in astronomical terms), only a few million years, but stars less massive than the Sun can get more than ten billion years old. Such small stars that formed in the beginning of the Universe still shine today. These ancient stars are very helpful to learn more about the early Universe, the First Stars and the history of the Milky Way. But how do you recognise an ancient star? Using their chemical fingerprints! In the beginning of the Universe, there were only two chemical elements: hydrogen and helium (and a tiny bit of lithium). All the heavier elements like carbon, calcium and iron were only made later within stars and their explosions. The amount of chemical elements in the Universe increases with the number of stars that are born, evolve and explode. Stars that form later are born with more heavy elements, or a greater metallicity. In the field of astronomy that is called “Galactic Archaeology”, stars of various metallicities are used to study the history of the Milky Way. In this doctoral thesis, the focus is on metal-poor stars because these are expected to be the oldest and can therefore tell us a lot about the early history of our Galaxy.
Until today, we still have not discovered a metal-free star. The most metal-poor stars, however, give us important insights in the lives and deaths of the First Stars. Many of the oldest, most metal-poor stars have an unexpectedly large amount of carbon, compared to for example iron. These carbon-enhanced metal-poor (CEMP) stars tell us something about the very first stars in the Universe: they somehow produced a lot of carbon. If we look at the precise chemical fingerprints of the CEMP stars, we can learn a lot more. But our interpretation depends on the assumption that the chemical fingerprint of a star does not change during its life. In this thesis, new data is presented that shows that this assumption may be too simple: many extremely metal-poor CEMP stars are members of binary systems. Interactions between two stars in a binary system can pollute the surface of the stars. Likely not all of the CEMP stars in binary systems were actually polluted, but we should be very careful in our interpretations of the fingerprints of these stars.
The CEMP stars and other metal-poor stars are also important for our understanding of the early history of the Milky Way. Most researchers who study metal-poor stars look for these stars in the halo of the Milky Way: a huge diffuse Galactic component containing about 1% of the stars in our Galaxy. However, models predict that the oldest metal-poor stars are located in the center of the Milky Way, in the bulge. The metal-poor inner Galaxy is unfortunately difficult to study due to large amounts of dust between us and the center and an overwhelming majority of metal-rich stars. This thesis presents results from the successful Pristine Inner Galaxy Survey (PIGS), a new survey looking for (and finding) the oldest stars in the bulge of the Milky Way. PIGS is using images with a specific color that is sensitive to the metallicity of stars, and can therefore efficiently select the metal-poor stars among millions of other, more metal-rich stars. The interesting candidates are followed up with spectroscopy, which is then analysed using two independent methods. With this strategy, PIGS has discovered the largest sample of metal-poor stars in the inner Galaxy to date. A new result from the PIGS data is that the metal-poor stars rotate more slowly around the Galactic center compared to the more metal-rich stars, and they show larger randomness in their motions as well. Another important contribution from PIGS is the discovery of tens of CEMP stars in the inner Galaxy, where previously only two such stars were known.
The new results from this thesis help us to understand the First Stars and the early history of the Milky Way. Ongoing and future large surveys will provide us with a lot of additional data in the coming years. It is an exciting time for the field of Galactic Archaeology.
Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
In this dissertation we introduce a concept of light driven active and passive manipulation of colloids trapped at solid/liquid interface. The motion is induced due to generation of light driven diffusioosmotic flow (LDDO) upon irradiation with light of appropriate wavelength. The origin of the flow is due to osmotic pressure gradient resulting from a concentration gradient at the solid/liquid interface of the photosensitive surfactant present in colloidal dispersion. The photosensitive surfactant consists of a cationic head group and a hydrophobic tail in which azobenzene group is integrated in. The azobenzene is known to undergo reversible photo-isomerization from a stable trans to a meta stable cis state under irradiation with UV light. Exposure to light of larger wavelength results in back photo-isomerization from cis to trans state. The two isomers have different molecular properties, for instance, trans isomer has a rod like structure and low polarity (0 dipole moment), whereas cis one is bent and has a dipole moment of ~3 Debye. Being integrated in the hydrophobic tail of the surfactant molecule, the azobenzene state determines the hydrophobicity of the whole molecule: in the trans state the surfactant is more hydrophobic than in the cis-state. In this way many properties of the surfactant such as the CMC, solubility and the interaction potential with a solid surface can be altered by light. When the solution containing such a surfactant is irradiated with focused light, a concentration gradient of different isomers is formed near the boundary of the irradiated area near the solid surface resulting in osmotic pressure gradient. The generated diffusioosmotic (DO) flow carries the particles passively along.
The local-LDDO flow can be generated around and by each particle when mesoporous silica colloids are dispersed in the surfactant solution. This is because porous particles act as a sink/source which absorbs azobenzene molecule in trans state and expels it when it is in the cis state. The DO flows generated at each particle interact resulting in aggregation or separation depending upon the initial state of surfactant molecules. The kinetic of aggregation and separation can be controlled and manipulated by altering the parameters such as the wavelength and intensity of the applied light, as well as surfactant and particle concentration. Using two wavelengths simultaneously allows for dynamic gathering and separation creating fascinating patterns such as 2D disk of well separated particles or establishing collective complex behaviour of particle ensemble as described in this thesis.
The mechanism of l-LDDO is also used to generate self-propelled motion. This is possible when half of the porous particle is covered by metal layer, basically blocking the pores on one side. The LDDO flow generated on uncapped side pushes the particle forward resulting in a super diffusive motion. The system of porous particle and azobenzene containing surfactant molecule can be utilized for various application such as drug delivery, cargo transportation, self-assembling, micro motors/ machines or micro patterning.
The Earth's inner magnetosphere is a very dynamic system, mostly driven by the external solar wind forcing exerted upon the magnetic field of our planet. Disturbances in the solar wind, such as coronal mass ejections and co-rotating interaction regions, cause geomagnetic storms, which lead to prominent changes in charged particle populations of the inner magnetosphere - the plasmasphere, ring current, and radiation belts. Satellites operating in the regions of elevated energetic and relativistic electron fluxes can be damaged by deep dielectric or surface charging during severe space weather events. Predicting the dynamics of the charged particles and mitigating their effects on the infrastructure is of particular importance, due to our increasing reliance on space technologies.
The dynamics of particles in the plasmasphere, ring current, and radiation belts are strongly coupled by means of collisions and collisionless interactions with electromagnetic fields induced by the motion of charged particles. Multidimensional numerical models simplify the treatment of transport, acceleration, and loss processes of these particles, and allow us to predict how the near-Earth space environment responds to solar storms. The models inevitably rely on a number of simplifications and assumptions that affect model accuracy and complicate the interpretation of the results. In this dissertation, we quantify the processes that control electron dynamics in the inner magnetosphere, paying particular attention to the uncertainties of the employed numerical codes and tools.
We use a set of convenient analytical solutions for advection and diffusion equations to test the accuracy and stability of the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. We show that numerical schemes implemented in the code converge to the analytical solutions and that the VERB-4D code demonstrates stable behavior independent of the assumed time step. The order of the numerical scheme for the convection equation is demonstrated to affect results of ring current and radiation belt simulations, and it is crucially important to use high-order numerical schemes to decrease numerical errors in the model.
Using the thoroughly tested VERB-4D code, we model the dynamics of the ring current electrons during the 17 March 2013 storm. The discrepancies between the model and observations above 4.5 Earth's radii can be explained by uncertainties in the outer boundary conditions. Simulation results indicate that the electrons were transported from the geostationary orbit towards the Earth by the global-scale electric and magnetic fields.
We investigate how simulation results depend on the input models and parameters. The model is shown to be particularly sensitive to the global electric field and electron lifetimes below 4.5 Earth's radii. The effects of radial diffusion and subauroral polarization streams are also quantified.
We developed a data-assimilative code that blends together a convection model of energetic electron transport and loss and Van Allen Probes satellite data by means of the Kalman filter. We show that the Kalman filter can correct model uncertainties in the convection electric field, electron lifetimes, and boundary conditions. It is also demonstrated how the innovation vector - the difference between observations and model prediction - can be used to identify physical processes missing in the model of energetic electron dynamics.
We computed radial profiles of phase space density of ultrarelativistic electrons, using Van Allen Probes measurements. We analyze the shape of the profiles during geomagnetically quiet and disturbed times and show that the formation of new local minimums in the radial profiles coincides with the ground observations of electromagnetic ion-cyclotron (EMIC) waves. This correlation indicates that EMIC waves are responsible for the loss of ultrarelativistic electrons from the heart of the outer radiation belt into the Earth's atmosphere.
RainNet v1.0
(2020)
In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting. Its design was inspired by the U-Net and SegNet families of deep learning models, which were originally designed for binary segmentation tasks. RainNet was trained to predict continuous precipitation intensities at a lead time of 5min, using several years of quality-controlled weather radar composites provided by the German Weather Service (DWD). That data set covers Germany with a spatial domain of 900km × 900km and has a resolution of 1km in space and 5min in time. Independent verification experiments were carried out on 11 summer precipitation events from 2016 to 2017. In order to achieve a lead time of 1h, a recursive approach was implemented by using RainNet predictions at 5min lead times as model inputs for longer lead times. In the verification experiments, trivial Eulerian persistence and a conventional model based on optical flow served as benchmarks. The latter is available in the rainymotion library and had previously been shown to outperform DWD's operational nowcasting model for the same set of verification events.
RainNet significantly outperforms the benchmark models at all lead times up to 60min for the routine verification metrics mean absolute error (MAE) and the critical success index (CSI) at intensity thresholds of 0.125, 1, and 5mm h⁻¹. However, rainymotion turned out to be superior in predicting the exceedance of higher intensity thresholds (here 10 and 15mm h⁻¹). The limited ability of RainNet to predict heavy rainfall intensities is an undesirable property which we attribute to a high level of spatial smoothing introduced by the model. At a lead time of 5min, an analysis of power spectral density confirmed a significant loss of spectral power at length scales of 16km and below. Obviously, RainNet had learned an optimal level of smoothing to produce a nowcast at 5min lead time. In that sense, the loss of spectral power at small scales is informative, too, as it reflects the limits of predictability as a function of spatial scale. Beyond the lead time of 5min, however, the increasing level of smoothing is a mere artifact – an analogue to numerical diffusion – that is not a property of RainNet itself but of its recursive application. In the context of early warning, the smoothing is particularly unfavorable since pronounced features of intense precipitation tend to get lost over longer lead times. Hence, we propose several options to address this issue in prospective research, including an adjustment of the loss function for model training, model training for longer lead times, and the prediction of threshold exceedance in terms of a binary segmentation task. Furthermore, we suggest additional input data that could help to better identify situations with imminent precipitation dynamics. The model code, pretrained weights, and training data are provided in open repositories as an input for such future studies.
Fit für die Lehre. Und nun?
(2020)
Anlässlich des zehnjährigen Jubiläums der Zertifikatsprogramme Teaching Professionals wurden die Absolvent/ innen mittels eines Online-Fragebogens befragt. Dieser Werkstattbericht gibt erste Einblicke in die Ergebnisse zum Übergang des wissenschaftlichen Nachwuchses in berufliche Tätigkeitsfelder nach hochschuldidaktischer Weiterbildung, auch im Hinblick auf den Stellenwert von Lehrqualifikation in Bewerbungs- und Berufungsverfahren.
Real-world scene perception is typically studied in the laboratory using static picture viewing with restrained head position. Consequently, the transfer of results obtained in this paradigm to real-word scenarios has been questioned. The advancement of mobile eye-trackers and the progress in image processing, however, permit a more natural experimental setup that, at the same time, maintains the high experimental control from the standard laboratory setting. We investigated eye movements while participants were standing in front of a projector screen and explored images under four specific task instructions. Eye movements were recorded with a mobile eye-tracking device and raw gaze data were transformed from head-centered into image-centered coordinates. We observed differences between tasks in temporal and spatial eye-movement parameters and found that the bias to fixate images near the center differed between tasks. Our results demonstrate that current mobile eye-tracking technology and a highly controlled design support the study of fine-scaled task dependencies in an experimental setting that permits more natural viewing behavior than the static picture viewing paradigm.
Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3-D thermomechanical models we show that the deformation regime, which defines formation of single-slab or multi-slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large-scale lithospheric extension rate. Our model results indicate that on present-day Earth multi-slab plume-induced subduction is initiated only if the oceanic lithosphere is relatively young (<30-40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single-slab subduction is facilitated by older lithosphere and pre-imposed extensional stresses. In early Earth, plume-lithosphere interaction could have led to formation of either episodic short-lived circular subduction when the oceanic lithosphere was young or to multi-slab subduction when the lithosphere was old.
Glycosylphosphatidylinositols (GPIs) are highly complex glycolipids that serve as membrane anchors to a large variety of eukaryotic proteins. These are covalently attached to a group of peripheral proteins called GPI-anchored proteins (GPI-APs) through a post-translational modification in the endoplasmic reticulum. The GPI anchor is a unique structure composed of a glycan, with phospholipid tail at one end and a phosphoethanolamine linker at the other where the protein attaches. The glycan part of the GPI comprises a conserved pseudopentasaccharide core that could branch out to carry additional glycosyl or phosphoethanolamine units. GPI-APs are involved in a diverse range of cellular processes, few of which are signal transduction, protein trafficking, pathogenesis by protozoan parasites like the malaria- causing parasite Plasmodium falciparum. GPIs can also exist freely on the membrane surface without an attached protein such as those found in parasites like Toxoplasma gondii, the causative agent of Toxoplasmosis. These molecules are both structurally and functionally diverse, however, their structure-function relationship is still poorly understood. This is mainly because no clear picture exists regarding how the protein and the glycan arrange with respect to the lipid layer. Direct experimental evidence is rather scarce, due to which inconclusive pictures have emerged, especially regarding the orientation of GPIs and GPI-APs on membrane surfaces and the role of GPIs in membrane organization. It appears that computational modelling through molecular dynamics simulations would be a useful method to make progress. In this thesis, we attempt to explore characteristics of GPI anchors and GPI-APs embedded in lipid bilayers by constructing molecular models at two different resolutions – all-atom and coarse-grained.
First, we show how to construct a modular molecular model of GPIs and GPI-anchored proteins that can be readily extended to a broad variety of systems, addressing the micro-heterogeneity of GPIs. We do so by creating a hybrid link to which GPIs of diverse branching and lipid tails of varying saturation with their optimized force fields, GLYCAM06 and Lipid14 respectively, can be attached. Using microsecond simulations, we demonstrate that GPI prefers to “flop-down” on the membrane, thereby, strongly interacting with the lipid heads, over standing upright like a “lollipop”. Secondly, we extend the model of the GPI core to carry out a systematic study of the structural aspects of GPIs carrying different side chains (parasitic and human GPI variants) inserted in lipid bilayers. Our results demonstrate the importance of the side branch residues as these are the most accessible, and thereby, recognizable epitopes. This finding qualitatively agrees with experimental observations that highlight the role of the side branches in immunogenicity of GPIs and the specificity thereof. The overall flop-down orientation of the GPIs with respect to the bilayer surface presents the side chain residues to face the solvent. Upon attaching the green fluorescent protein (GFP) to the GPI, it is seen to lie in close proximity to the bilayer, interacting both with the lipid heads and glycan part of the GPI. However the orientation of GFP is sensitive to the type of GPI it is attached to. Finally, we construct a coarse-grained model of the GPI and GPI-anchored GFP using a modified version of the MARTINI force-field, using which the timescale is enhanced by at least an order of magnitude compared to the atomistic system.
This study provides a theoretical perspective on the conformational behavior of the GPI core and some of its branched variations in presence of lipid bilayers, as well as draws comparisons with experimental observations. Our modular atomistic model of GPI can be further employed to study GPIs of variable branching, and thereby, aid in designing future experiments especially in the area of vaccines and drug therapies. Our coarse-grained model can be used to study dynamic aspects of GPIs and GPI-APs w.r.t plasma membrane organization. Furthermore, the backmapping technique of converting coarse-grained trajectory back to the atomistic model would enable in-depth structural analysis with ample conformational sampling.
Coarse-grained molecular model for the Glycosylphosphatidylinositol anchor with and without protein
(2020)
Glycosylphosphatidylinositol (GPI) anchors are a unique class of complex glycolipids that anchor a great variety of proteins to the extracellular leaflet of plasma membranes of eukaryotic cells. These anchors can exist either with or without an attached protein called GPI-anchored protein (GPI-AP) both in vitro and in vivo. Although GPIs are known to participate in a broad range of cellular functions, it is to a large extent unknown how these are related to GPI structure and composition. Their conformational flexibility and microheterogeneity make it difficult to study them experimentally. Simplified atomistic models are amenable to all-atom computer simulations in small lipid bilayer patches but not suitable for studying their partitioning and trafficking in complex and heterogeneous membranes. Here, we present a coarse-grained model of the GPI anchor constructed with a modified version of the MARTINI force field that is suited for modeling carbohydrates, proteins, and lipids in an aqueous environment using MARTINI's polarizable water. The nonbonded interactions for sugars were reparametrized by calculating their partitioning free energies between polar and apolar phases. In addition, sugar-sugar interactions were optimized by adjusting the second virial coefficients of osmotic pressures for solutions of glucose, sucrose, and trehalose to match with experimental data. With respect to the conformational dynamics of GPI-anchored green fluorescent protein, the accessible time scales are now at least an order of magnitude larger than for the all-atom system. This is particularly important for fine-tuning the mutual interactions of lipids, carbohydrates, and amino acids when comparing to experimental results. We discuss the prospective use of the coarse-grained GPI model for studying protein-sorting and trafficking in membrane models.
Studies on the unsustainable use of groundwater resources are still considered incipient since it is frequently a poorly understood and managed, devalued and inadequately protected natural resource. Groundwater Recharge (GWR) is one of the most challenging elements to estimate since it can rarely be measured directly and cannot easily be derived from existing data. To overcome these limitations, many hydro(geo)logists have combined different approaches to estimate large-scale GWR, namely: remote sensing products, such as IMERG product; Water Budget Equation, also in combination with hydrological models, and; Geographic Information System (GIS), using estimation formulas. For intermediary-scale GWR estimation, there exist: Non-invasive Cosmic-Ray Neutron Sensing (CRNS); wireless networks from local soil probes; and soil hydrological models, such as HYDRUS. Accordingly, this PhD thesis aims, on the one hand, to demonstrate a GIS-based model coupling for estimating the GWR distribution on a large scale in tropical wet basins. On the other hand, it aims to use the time series from CRNS and invasive soil moisture probes to inversely calibrate the soil hydraulic properties, and based on this, estimating the intermediary-scale GWR using a soil hydrological model. For such purpose, two tropical wet basins located in a complex sedimentary aquifer in the coastal Northeast region of Brazil were selected. These are the João Pessoa Case Study Area and the Guaraíra Experimental Basin. Several satellite products in the first area were used as input to the GIS-based water budget equation model for estimating the water balance components and GWR in 2016 and 2017. In addition, the point-scale measurement and CRNS data were used in the second area to determine the soil hydraulic properties, and to estimate the GWR in the 2017-2018 and 2018-2019 hydrological years. The resulting values of GWR on large- and intermediary-scale were then compared and validated by the estimates obtained by groundwater table fluctuations. The GWR rates for IMERG- and rain-gauge-based scenarios showed similar coefficients between 68% and 89%, similar mean errors between 30% and 34%, and slightly-different bias between -13% and 11%. The results of GWR rates for soil probes and CRNS soil moisture scenarios ranged from -5.87 to -61.81 cm yr-1, which corresponds to 5% and 38% of the precipitation. The calculations of the mean GWR rates on large-scale, based on remote sensing data, and on intermediary-scale, based on CRNS data, held similar results for the Podzol soil type, namely 17.87% and 17% of the precipitation. It is then concluded that the proposed methodologies allowed for estimating realistically the GWR over the study areas, which can be a ground-breaking step towards improving the water management and decision-making in the Northeast of Brazil.
Background Recent shoulder injury prevention programs have utilized resistance exercises combined with different forms of instability, with the goal of eliciting functional adaptations and thereby reducing the risk of injury. However, it is still unknown how an unstable weight mass (UWM) affects the muscular activity of the shoulder stabilizers. Aim of the study was to assess neuromuscular activity of dynamic shoulder stabilizers under four conditions of stable and UWM during three shoulder exercises. It was hypothesized that a combined condition of weight with UWM would elicit greater activation due to the increased stabilization demand. Methods Sixteen participants (7 m/9 f) were included in this cross-sectional study and prepared with an EMG-setup for the: Mm. upper/lower trapezius (U.TA/L.TA), lateral deltoid (DE), latissimus dorsi (LD), serratus anterior (SA) and pectoralis major (PE). A maximal voluntary isometric contraction test (MVIC; 5 s.) was performed on an isokinetic dynamometer. Next, internal/external rotation (In/Ex), abduction/adduction (Ab/Ad) and diagonal flexion/extension (F/E) exercises (5 reps.) were performed with four custom-made-pipes representing different exercise conditions. First, the empty-pipe (P; 0.5 kg) and then, randomly ordered, water-filled-pipe (PW; 1 kg), weight-pipe (PG; 4.5 kg) and weight + water-filled-pipe (PWG; 4.5 kg), while EMG was recorded. Raw root-mean-square values (RMS) were normalized to MVIC (%MVIC). Differences between conditions for RMS%MVIC, scapular stabilizer (SR: U.TA/L.TA; U.TA/SA) and contraction (CR: concentric/eccentric) ratios were analyzed (paired t-test; p <= 0.05; Bonferroni adjusted alpha = 0.008). Results PWG showed significantly greater muscle activity for all exercises and all muscles except for PE compared to P and PW. Condition PG elicited muscular activity comparable to PWG (p > 0.008) with significantly lower activation of L.TA and SA in the In/Ex rotation. The SR ratio was significantly higher in PWG compared to P and PW. No significant differences were found for the CR ratio in all exercises and for all muscles. Conclusion Higher weight generated greater muscle activation whereas an UWM raised the neuromuscular activity, increasing the stabilization demands. Especially in the In/Ex rotation, an UWM increased the RMS%MVIC and SR ratio. This might improve training effects in shoulder prevention and rehabilitation programs.
Consensify
(2020)
A standard practise in palaeogenome analysis is the conversion of mapped short read data into pseudohaploid sequences, frequently by selecting a single high-quality nucleotide at random from the stack of mapped reads. This controls for biases due to differential sequencing coverage, but it does not control for differential rates and types of sequencing error, which are frequently large and variable in datasets obtained from ancient samples. These errors have the potential to distort phylogenetic and population clustering analyses, and to mislead tests of admixture using D statistics. We introduce Consensify, a method for generating pseudohaploid sequences, which controls for biases resulting from differential sequencing coverage while greatly reducing error rates. The error correction is derived directly from the data itself, without the requirement for additional genomic resources or simplifying assumptions such as contemporaneous sampling. For phylogenetic and population clustering analysis, we find that Consensify is less affected by artefacts than methods based on single read sampling. For D statistics, Consensify is more resistant to false positives and appears to be less affected by biases resulting from different laboratory protocols than other frequently used methods. Although Consensify is developed with palaeogenomic data in mind, it is applicable for any low to medium coverage short read datasets. We predict that Consensify will be a useful tool for future studies of palaeogenomes.
The Southern Central Andes (33°-36°S) are an excellent natural laboratory to study orogenic deformation processes, where boundary conditions, such as the geometry of the subducted plate, impose an important control on the evolution of the orogen. On the other hand, the South American plate presents a series of heterogeneities that additionally impart control on the mode of deformation. This thesis aims to test the control of this last factor over the construction of the Cenozoic Andean orogenic system.
From the integration of surface and subsurface information in the southern area (34-36°S), the evolution of Andean deformation over the steeply dipping subduction segment was studied. A structural model was developed evaluating the stress state from the Miocene to the present-day and its influence in the migration of magmatic fluids and hydrocarbons. Based on these data, together with the data generated by other researchers in the northern zone of the study area (33-34°S), geodynamic numerical modeling was performed to test the hypothesis of the decisive role of upper-plate heterogeneities in the Andean evolution. Geodynamic codes (LAPEX-2D and ASPECT) which simulate the behavior of materials with elasto-visco-plastic rheologies under deformation, were used. The model results suggest that upper-plate contractional deformation is significantly controlled by the strength of the lithosphere, which is defined by the composition of the upper and lower crust, and by the proportion of lithospheric mantle, which in turn is determined by previous tectonic events. In addition, the previous regional tectono-magmatic events also defined the composition of the crust and its geometry, which is another factor that controls the localization of deformation. Accordingly, with more felsic lower crustal composition, the deformation follows a pure-shear mode, while more mafic compositions induce a simple-shear deformation mode. On the other hand, it was observed that initial lithospheric thickness may fundamentally control the location of deformation, with zones characterized by thin lithosphere are prone to concentrate it. Finally, it was found that an asymmetric lithosphere-astenosphere boundary resulting from corner flow in the mantle wedge of the eastward-directed subduction zone tends to generate east-vergent detachments.
Editorial
(2020)
SandBlocks
(2020)
Visuelle Programmiersprachen werden heutzutage zugunsten textueller Programmiersprachen nahezu nicht verwendet, obwohl visuelle Programmiersprachen einige Vorteile bieten. Diese reichen von der Vermeidung von Syntaxfehlern, über die Nutzung konkreter domänenspezifischer Notation bis hin zu besserer Lesbarkeit und Wartbarkeit des Programms. Trotzdem greifen professionelle Softwareentwickler nahezu ausschließlich auf textuelle Programmiersprachen zurück.
Damit Entwickler diese Vorteile visueller Programmiersprachen nutzen können, aber trotzdem nicht auf die ihnen bekannten textuellen Programmiersprachen verzichten müssen, gibt es die Idee, textuelle und visuelle Programmelemente gemeinsam in einer Programmiersprache nutzbar zu machen. Damit ist dem Entwickler überlassen wann und wie er visuelle Elemente in seinem Programmcode verwendet.
Diese Arbeit stellt das SandBlocks-Framework vor, das diese gemeinsame Nutzung visueller und textueller Programmelemente ermöglicht. Neben einer Auswertung visueller Programmiersprachen, zeigt es die technische Integration visueller Programmelemente in das Squeak/Smalltalk-System auf, gibt Einblicke in die Umsetzung und Verwendung in Live-Programmiersystemen und diskutiert ihre Verwendung in unterschiedlichen Domänen.
Digitale Plattformen
(2020)
Obwohl digitale Plattformen vornehmlich von Großunternehmen betrieben werden, bieten sie klein- und mittelständischen Unternehmen (KMU) Potenziale zur Verbreitung innovativer Technologien und für den Ausbau ihres Geschäftsmodells. Für die Umsetzung digitaler Plattformen stehen Unternehmen mehrere Strategien zur Verfügung. Der Beitrag vergleicht und bewertet grundlegende Strategien am Beispiel eines Maschinenbauunternehmens. Die Ergebnisse dienen als Grundlage für die Entscheidungsfindung von KMU.
This article explores the structural diversity of intraministerial organization over time. Based on organization theory, it proposes a generic typology for intraministerial units applicable to any hierarchically structured government organization. We empirically investigate the critical case of the German federal bureaucracy. By classifying its subunits, we analyze the longitudinal development of structural differentiation and its correspondence to denominational variety. The data stem from a novel international dataset, covering all ministries between 1980 and 2015. We find that intraministerial structure differentiates over time, across and within ministries. A stable core of traditional Weberian structure is complemented by structurally innovative intraministerial units. We conclude that the German federal bureaucracy is more diverse than suggested in previous literature. Our findings indicate that less Weberian bureaucracies are at least as structurally diverse and that more reform-driven bureaucracies will have experienced at least as many changes in structural diversity.
During the last decade, intracellular actin waves have attracted much attention due to their essential role in various cellular functions, ranging from motility to cytokinesis. Experimental methods have advanced significantly and can capture the dynamics of actin waves over a large range of spatio-temporal scales. However, the corresponding coarse-grained theory mostly avoids the full complexity of this multi-scale phenomenon. In this perspective, we focus on a minimal continuum model of activator–inhibitor type and highlight the qualitative role of mass conservation, which is typically overlooked. Specifically, our interest is to connect between the mathematical mechanisms of pattern formation in the presence of a large-scale mode, due to mass conservation, and distinct behaviors of actin waves.
Ein wichtiges Anliegen aller Privatrechtsordnungen ist die Sicherheit und Verlässlichkeit des Gütertransfers. In einer entwickelten Wirtschaft, die auf Arbeitsteilung und Umsatz basiert, gibt es lange Lieferketten. Person A liefert ein Gut an B, dann liefert B an C und immer so weiter. Die einzelnen Glieder in der Kette müssen das Gut sicher und verlässlich erwerben können. Wenn nun aber das Geschäft zwischen A und B von Anfang an ungültig ist oder nachträglich hinfällig wird, stellt sich die Frage, wem das Gut gehört. Das deutsche Recht begegnet dieser Frage unter anderem mit dem Trennungs- und Abstraktionsprinzip: Kauf und Übereignung sind zwei gesonderte Verträge, und die Wirksamkeit der Übereignung ist unabhängig vom Bestand und von der Wirksamkeit des Kaufvertrag. Das wird von deutschen Juristen als Schlüssel wissenschaftlichen Rechtsdenkens hochgehalten, stößt aber außerhalb Deutschlands und speziell in Frankreich auf Unverständnis. Denn im französischen Recht sind Kauf und Übereignung Eins.
Im Folgenden geht es nicht so sehr um die geistige Qualität des deutschen Trennungs- und Abstraktionsprinzips, die unbestreitbar ist, sondern vor allem um die Frage, ob diese Prinzi-pien im Vergleich zur französischen Einheit von Kauf und Übereignung praktische Vorteile haben. Die Untersuchung konzentriert sich auf die Übertragung von beweglichen Sachen und von Rechten. Das Grundstücksrecht bleibt dagegen ausgeklammert, denn es ist wegen seiner Formalien schwerer zu vergleichen und trägt keine grundlegend neuen Erkenntnisse bei.
Carbonates play a key role in the chemistry and dynamics of our planet. They are directly connected to the CO2 budget of our atmosphere and have a great impact on the deep carbon cycle. Moreover, recent studies have shown that carbonates are stable along the geothermal gradient down to Earth's lower mantle conditions, changing their crystal structure and related properties. Subducted carbonates may also react with silicates to form new phases. These reactions will redistribute elements, such as calcium (Ca), magnesium (Mg), iron (Fe) and carbon in the form of carbon dioxide (CO2), but also trace elements, that are carried by the carbonates. The trace elements of most interest are strontium (Sr) and rare earth elements (REE) which have been found to be important constituents in the composition of the primitive lower mantle and in mineral inclusions found in super-deep diamonds. However, the stability of carbonates in presence of mantle silicates at relevant temperatures is far from being well understood. Related to this, very little is known about distribution processes of trace elements between carbonates and mantle silicates. To shed light on these processes, we studied reactions between Sr- and REE-containing CaCO3 and Mg/Fe-bearing silicates of the system (Mg,Fe)2SiO4 - (Mg,Fe)SiO3 at high pressure and high temperature using synchrotron radiation based μ-X-ray diffraction (μ-XRD) and μ-X-ray fluorescence (μ-XRF) with μm-resolution in a laser-heated diamond anvil cell. X-ray diffraction is used to derive the structural changes of the phase reactions whereas X-ray fluorescence gives information on the chemical changes in the sample. In-situ experiments at high pressure and high temperature were performed at beamline P02.2 at PETRA III (Hamburg, Germany) and at beamline ID27 at ESRF (Grenoble, France). In addition to μ-XRD and μ-XRF, ex-situ measurements were made on the recovered sample material using transmission electron microscopy (TEM) and provided further insights into the reaction kinetics of carbonate-silicate reactions.
Our investigations show that CaCO3 is unstable in presence of mantle silicates above 1700 K and a reaction takes place in which magnesite plus CaSiO3-perovskite are formed. In addition, we observed that a high content of iron in the carbonate-silicate system favours dolomite formation during the reaction. The subduction of natural carbonates with significant amounts of Sr leads to a comprehensive investigation of the stability not only of CaCO3 phases in contact with mantle silicates but also of SrCO3 (and of Sr-bearing CaCO3). We found that SrCO3 reacts with (Mg,Fe)SiO3-perovskite to form magnesite and gained evidence for the formation of SrSiO3-perovskite.
To complement our study on the stability of SrCO3 at conditions of the Earth's lower mantle, we performed powder X-ray diffraction and single crystal X-ray diffraction experiments at ambient temperature and up to 49 GPa. We observed a transformation from SrCO3-I into a new high-pressure phase SrCO3-II at around 26 GPa with Pmmn crystal structure and a bulk modulus of 103(10) GPa. This information is essential to fully understand the phase behaviour and stability of carbonates in the Earth's lower mantle and to elucidate the possibility of introducing Sr into mantle silicates by carbonate-silicate reactions.
Simultaneous recording of μ-XRD and μ-XRF in the μm-range over the heated areas provides spatial information not only about phase reactions but also on the elemental redistribution during the reactions. A comparison of the spatial intensity distribution of the XRF signal before and after heating indicates a change in the elemental distribution of Sr and an increase in Sr-concentration was found around the newly formed SrSiO3-perovskite. With the help of additional TEM analyses on the quenched sample material the elemental redistribution was studied at a sub-micrometer scale. Contrary to expectations from combined μ-XRD and μ-XRF measurements, we found that La and Eu were not incorporated into the silicate phases, instead they tend to form either isolated oxide phases (e.g. Eu2O3, La2O3) or hydroxyl-bastnäsite (La(CO3)(OH)). In addition, we observed the transformation from (Mg,Fe)SiO3-perovskite to low-pressure clinoenstatite during pressure release. The monoclinic structure (P21/c) of this phase allows the incorporation of Ca as shown by additional EDX analyses and, to a minor extent, Sr too.
Based on our experiments, we can conclude that a detection of the trace elements in-situ at high pressure and high temperature remains challenging. However, our first findings imply that silicates may incorporate the trace elements provided by the carbonates and indicate that carbonates may have a major effect on the trace element contents of mantle phases.
Submerged sequences of marine terraces potentially provide crucial information of past sea-level positions. However, the distribution and characteristics of drowned marine terrace sequences are poorly known at a global scale. Using bathymetric data and novel mapping and modeling techniques, we studied a submerged sequence of marine terraces in the Bay of Biscay with the objective to identify the distribution and morphologies of submerged marine terraces and the timing and conditions that allowed their formation and preservation. To accomplish the objectives a high-resolution bathymetry (5 m) was analyzed using Geographic Information Systems and TerraceM(R). The successive submerged terraces were identified using a Surface Classification Model, which linearly combines the slope and the roughness of the surface to extract fossil sea-cliffs and fossil rocky shore platforms. For that purpose, contour and hillshaded maps were also analyzed. Then, shoreline angles, a geomorphic marker located at the intersection between the fossil sea-cliff and platform, were mapped analyzing swath profiles perpendicular to the isobaths. Most of the submerged strandlines are irregularly preserved throughout the continental shelf. In summary, 12 submerged terraces with their shoreline angles between approximately: -13 m (T1), -30 and -32 m (T2), -34 and 41 m (T3), -44 and -47 m (T4), -49 and 53 m (T5), -55 and 58 m (T6), -59 and 62 m (T7), -65 and 67 m (T8), -68 and 70 m (T9), -74 and -77 m (T10), -83 and -86 m (T11) and -89 and 92 m (T12). Nevertheless, the ones showing the best lateral continuity and preservation in the central part of the shelf are T3, T4, T5, T7, T8, and T10. The age of the terraces has been estimated using a landscape evolution model. To simulate the formation and preservation of submerged terraces three different scenarios: (i) 20-0 ka; (ii) 128-0 ka; and (iii) 128-20 ka, were compared. The best scenario for terrace generation was between 128 and 20 Ka, where T3, T5, and T7 could have been formed.
The manual muscle test (MMT) is a flexible diagnostic tool, which is used in many disciplines, applied in several ways. The main problem is the subjectivity of the test. The MMT in the version of a “break test” depends on the tester’s force rise and the patient’s ability to resist the applied force. As a first step, the investigation of the reproducibility of the testers’ force profile is required for valid application. The study examined the force profiles of n = 29 testers (n = 9 experiences (Exp), n = 8 little experienced (LitExp), n = 12 beginners (Beg)). The testers performed 10 MMTs according to the test of hip flexors, but against a fixed leg to exclude the patient’s reaction. A handheld device recorded the temporal course of the applied force. The results show significant differences between Exp and Beg concerning the starting force (padj = 0.029), the ratio of starting to maximum force (padj = 0.005) and the normalized mean Euclidean distances between the 10 trials (padj = 0.015). The slope is significantly higher in Exp vs. LitExp (p = 0.006) and Beg (p = 0.005). The results also indicate that experienced testers show inter-tester differences and partly even a low intra-tester reproducibility. This highlights the necessity of an objective MMT-assessment. Furthermore, an agreement on a standardized force profile is required. A suggestion for this is given.
ABCB1/4 gallbladder cancer risk variants identified in India also show strong effects in Chileans
(2020)
Background: The first large-scale genome-wide association study of gallbladder cancer (GBC) recently identified and validated three susceptibility variants in the ABCB1 and ABCB4 genes for individuals of Indian descent. We investigated whether these variants were also associated with GBC risk in Chileans, who show the highest incidence of GBC worldwide, and in Europeans with a low GBC incidence.
Methods: This population-based study analysed genotype data from retrospective Chilean case-control (255 cases, 2042 controls) and prospective European cohort (108 cases, 181 controls) samples consistently with the original publication.
Results: Our results confirmed the reported associations for Chileans with similar risk effects. Particularly strong associations (per-allele odds ratios close to 2) were observed for Chileans with high Native American (=Mapuche) ancestry. No associations were noticed for Europeans, but the statistical power was low.
Conclusion: Taking full advantage of genetic and ethnic differences in GBC risk may improve the efficiency of current prevention programs.
Despite the increasing number of species invasions, the factors driving invasiveness are still under debate. This is particularly the case for “invisible” invasions by aquatic microbial species. Since in many cases only a few individuals or propagules enter a new habitat, their genetic variation is low and might limit their invasion success, known as the genetic bottleneck. Thus, a key question is, how genetic identity and diversity of invading species influences their invasion success and, subsequently, affect the resident community. We conducted invader-addition experiments using genetically different strains of the globally invasive, aquatic cyanobacterium Raphidiopsis raciborskii (formerly: Cylindrospermopsis raciborskii) to determine the role of invader identity and genetic diversity (strain richness) at four levels of herbivory. We tested the invasion success of solitary single strain invasions against the invader genetic diversity, which was experimentally increased up to ten strains (multi-strain populations). By using amplicon sequencing we determined the strain-specific invasion success in the multi-strain treatments and compared those with the success of these strains in the single-strain treatments. Furthermore, we tested for the invasion success under different herbivore pressures. We showed that high grazing pressure by a generalist herbivore prevented invasion, whereas a specialist herbivore enabled coexistence of consumer and invader. We found a weak effect of diversity on invasion success only under highly competitive conditions. When invasions were successful, the magnitude of this success was strain-specific and consistent among invasions performed with single-strain or multi-strain populations. A strain-specific effect was also observed on the resident phytoplankton community composition, highlighting the strong role of invader genetic identity. Our results point to a strong effect of the genetic identity on the invasion success under low predation pressure. The genetic diversity of the invader population, however, had little effect on invasion success in our study, in contrast to most previous findings. Instead, it is the interaction between the consumer abundance and type together with the strain identity of the invader that defined invasion success. This study underlines the importance of strain choice in invasion research and in ecological studies in general.
Recent studies have suggested that musical rhythm perception ability can affect the phonological system. The most prevalent causal account for developmental dyslexia is the phonological deficit hypothesis. As rhythm is a subpart of phonology, we hypothesized that reading deficits in dyslexia are associated with rhythm processing in speech and in music. In a rhythmic grouping task, adults with diagnosed dyslexia and age-matched controls listened to speech streams with syllables alternating in intensity, duration, or neither, and indicated whether they perceived a strong-weak or weak-strong rhythm pattern. Additionally, their reading and musical rhythm abilities were measured. Results showed that adults with dyslexia had lower musical rhythm abilities than adults without dyslexia. Moreover, lower musical rhythm ability was associated with lower reading ability in dyslexia. However, speech grouping by adults with dyslexia was not impaired when musical rhythm perception ability was controlled: like adults without dyslexia, they showed consistent preferences. However, rhythmic grouping was predicted by musical rhythm perception ability, irrespective of dyslexia. The results suggest associations among musical rhythm perception ability, speech rhythm perception, and reading ability. This highlights the importance of considering individual variability to better understand dyslexia and raises the possibility that musical rhythm perception ability is a key to phonological and reading acquisition.
Organizations incorporate the institutional demands from their environment in order to be deemed legitimate and survive. Yet, complexifying societies promulgate multiple and sometimes inconsistent institutional prescriptions. When these prescriptions collide, organizations are said to face “institutional complexity”. How does an organization then incorporate incompatible demands? What are the consequences of institutional complexity for an organization? The literature provides contradictory conceptual and empirical insights on the matter. A central assumption, however, remains that internal incompatibilities generate tensions that, under certain conditions, can escalate into intractable conflicts, resulting in dysfunctionality and loss of legitimacy. The present research is an inquiry into what happens inside an organization when it incorporates complex institutional demands.
To answer this question, I focus on how individuals inside an organization interpret a complex institutional prescription. I examine how members of the French Development Agency interpret ‘results-based management’, a central but complex concept of organizing in the field of development aid. I use an inductive mixed methods design to systematically explore how different interpretations of results-based management relate to one another and to the organizational context in which they are embedded.
The results reveal that results-based management is a contested concept in the French Development Agency. I find multiple interpretations of the concept, which are attached to partly incompatible rationales about “who we are” and “what we do as an organization”. These rationales nevertheless coexist as balanced forces, without escalating into open conflict. The analysis points to four reasons for this peaceful coexistence of diverging rationales inside one and the same organization: 1) individuals’ capacity to manipulate different interpretations of a complex institutional demand, 2) the nature of interpretations, which makes them more or less prone to conflict, 3) the balanced distribution of rationales across the organizational sub-contexts and 4) the shared rules of interpretation provided by the larger socio-cultural context.
This research shows that an organization that incorporates institutional complexity comes to represent different, partly incompatible things to its members without being at war with itself. In doing so, it contributes to our knowledge of institutional complexity and organizational hybridity. It also advances our understanding of internal organizational legitimacy and of the translation of managerial concepts in organizations.
Literacy acquisition is one of the primary goals of school education, and usually it takes place in the national language of the respective country. At the same time, schools accommodate pupils with different home languages who might or might not be fluent in the national language and who start from other linguistic backgrounds in their acquisition of literacy. While it is safe to say that schools with a monolingual policy are not prepared to deal with the factual multilingualism in their classrooms in a systematic way, bilingual pupils have to deal with it nonetheless.
The interdisciplinary and comparative research project “Literacy Acquisition in Schools in the Context of Migration and Multilingualism” (LAS) investigated the practical processes of literacy acquisition in two countries, Germany and Turkey, where the monolingual orientation of schools is as much a reality as are the multilingual backgrounds of many of their pupils. The basic assumption was that pupils cope with the ways they are engaged by the school – both socially and academically – based on their cultural and linguistic repertoires acquired biographically, providing them with more or less productive options regarding the acquisition of literary skills. By comparing the literary development of bilingual children with that of their monolingual classmates throughout one school year in the first and the seventh grade in Germany and Turkey, respectively, we found out that the restricting potential of multilingualism is located rather on the part of the schools than on the part of the pupils. While the individual bilingual pupil almost naturally uses his/her home language as a resource for literacy acquisition in the school language, schools still tend to regard the multilingual backgrounds of their pupils as irrelevant or even as an impediment to adequate schooling. We argue that by ignoring or even suppressing the specific linguistic potentials of bilingualism, bilingual pupils are put at a structural disadvantage.
This research report is the slightly revised but full version of the final study project report from 2011 that was until now not available as a quotable publication. While several years have passed since the primary research was finalized, the addressed issues have lost none of their relevance. The report is accompanied by numerous publications in the frame of the LAS project, as well as by a web page (https://www.uni-potsdam.de/de/daf/projekte/las), which also contains the presentations from the final LAS-Conference, including valuable discussions of the report from renowed experts in the field.
Orogenic peridotites represent portions of upper subcontinental mantle now incorporated in mountain belts. They often contain layers, lenses and irregular bodies of pyroxenite and eclogite. The origin of this heterogeneity and the nature of these layers is still debated but it is likely to involve processes such as transient melts coming from the crust or the mantle and segregating in magma conduits, crust-mantle interaction, upwelling of the asthenosphere and metasomatism. All these processes occur in the lithospheric mantle and are often related with the subduction of crustal rocks to mantle depths. In fact, during subduction, fluids and melts are released from the slab and can interact with the overlying mantle, making the study of deep melts in this environment crucial to understand mantle heterogeneity and crust-mantle interaction. The aim of this thesis is precisely to better constrain how such processes take place studying directly the melt trapped as primary inclusions in pyroxenites and eclogites. The Bohemian Massif, crystalline core of the Variscan belt, is targeted for these purposes because it contains orogenic peridotites with layers of pyroxenite and eclogite and other mafic rocks enclosed in felsic high pressure and ultra-high pressure crustal rocks. Within this Massif mafic rocks from two areas have been selected: the garnet clinopyroxenite in orogenic peridotite of the Granulitgebirge and the ultra-high pressure eclogite in the diamond-bearing gneisses of the Erzgebirge. In both areas primary melt inclusions were recognized in the garnet, ranging in size between 2-25 µm and with different degrees of crystallization, from glassy to polycrystalline. They have been investigated with Micro Raman spectroscopy and EDS mapping and the mineral assemblage is kumdykolite, phlogopite, quartz, kokchetavite, phase with a main Raman peak at 430 cm-1, phase with a main Raman peak at 412 cm-1, white mica and calcite with some variability in relative abundance depending on the case study. In the Granulitgebirge osumilite and pyroxene are also present, whereas calcite is one of the main phases in the Erzgebirge. The presence of glass and the mineral assemblage in the nanogranitoids suggest that they were former droplets of melt trapped in the garnet while it was growing. Glassy inclusions and re-homogenized nanogranitoids show a silicate melt that is granitic, hydrous, high in alkalis and weakly peraluminous. The melt is also enriched in both case studies in Cs, Pb, Rb, U, Th, Li and B suggesting the involvement of crustal component, i.e. white mica (main carrier of Cs, Pb, Rb, Li and B), and a fluid (Cs, Th and U) in the melt producing reaction. The whole rock in both cases mainly consists of garnet and clinopyroxene with, in Erzgebirge samples, the additional presence of quartz both in the matrix and as a polycrystalline inclusion in the garnet. The latter is interpreted as a quartz pseudomorph after coesite and occurs in the same microstructural position as the melt inclusions. Both rock types show a crustal and subduction zone signature with garnet and clinopyroxene in equilibrium. Melt was likely present during the metamorphic peak of the rock, as it occurs in garnet.
Our data suggest that the processes most likely responsible for the formation of the investigated rocks in both areas is a metasomatic reaction between a melt produced in the crust and mafic layers formerly located in the mantle wedge for the Granulitgebirge and in the subducted continental crust itself in the Erzgebirge. Thus metasomatism in the first case took place in the mantle overlying the slab, whereas in the second case metasomatism took place in the continental crust that already contained, before subduction, mafic layers. Moreover, the presence of former coesite in the same microstructural position of the melt inclusions in the Erzgebirge garnets suggest that metasomatism took place at ultra-high pressure conditions.
Summarizing, in this thesis we provide new insights into the geodynamic evolution of the Bohemian Massif based on the study of melt inclusions in garnet in two different mafic rock types, combining the direct microstructural and geochemical investigation of the inclusions with the whole-rock and mineral geochemistry. We report for the first time data, directly extracted from natural rocks, on the metasomatic melt responsible for the metasomatism of several areas of the Bohemian Massif. Besides the two locations here investigated, belonging to the Saxothuringian Zone, a signature similar to the investigated melt is clearly visible in pyroxenite and peridotite of the T-7 borehole (again Saxothuringian Zone) and the durbachite suite located in the Moldanubian Zone.
Social comparison processes and the social position within a school class already play a major role in performance evaluation as early as in elementary school. The influence of contrast and assimilation effects on self-evaluation of performance as well as task interest has been widely researched in observational studies under the labels big-fish-little-pond and basking-in-reflected-glory effect. This study examined the influence of similar contrast and assimilation effects in an experimental paradigm. Fifth and sixth grade students (n = 230) completed a computer-based learning task during which they received social comparative feedback based on 2 × 2 experimentally manipulated feedback conditions: social position (high vs. low) and peer performance (high vs. low). Results show a more positive development of task interest and self-evaluation of performance in both the high social position and the high peer performance condition. When applied to the school setting, results of this study suggest that students who already perform well in comparison to their peer group are also the ones who profit most from social comparative feedback, given that they are the ones who usually receive the corresponding positive performance feedback.
Aufgrund der aktuellen Bedrohung unserer liberalen demokratischen Gesellschaft durch extremistische Strömungen, Rechtspopulismus, Rassismus, Fake News und Hetze in sozialen Netzwerken steht das Thema Demokratiebildung zunehmend im Fokus bildungspolitischer Bemühungen. Die Publikation „Musikpädagogik als Beitrag zur Demokratiebildung“ greift diese aktuelle Thematik auf und stellt anhand von acht theoretischen und praxisbezogenen Fachbeiträgen aus der musikpädagogischen Forschung, der Bildungswissenschaft, dem schulischen Musikunterricht sowie außerschulischen musikalischen Lernkontexten die Potenziale verschiedener musikpädagogischer Unterrichtsformen, Inhalte und Methoden für die Demokratiebildung heraus. Auch Beiträge von Studierenden des Lehrstuhls für Musikpädagogik und Musikdidaktik der Universität Potsdam wurden in den Band aufgenommen. Es handelt sich dabei um ein überregional einsetzbares Studienmaterial, das erstmalig mehrperspektivisch musikalische Bildung im Kontext des Demokratielernens und -lebens in Theorie und Praxis diskutiert, bestehende Forschungsdesiderate aufzeigt und auch eine Verbindung zur Musiklehrkräftefortbildung sowie zu bildungspolitischen und ethischen Paradigmen zieht. Dabei werden bestehende Paradigmen und musikpädagogische Entwicklungen teils auch hinterfragt und Ideen für eine demokratiefördernde Musikpädagogik skizziert. Damit versteht sich die vorliegende Publikation als innovativer Beitrag zum musikpädagogischen und bildungspolitischen Diskurs, der Akzente für neue Entwicklungen setzt.
Enzyme degradable polymersomes from chitosan-g-[poly-l-lysine-block-epsilon-caprolactone] copolymer
(2020)
The scope of this study includes the synthesis of chitosan-g-[peptide-poly-epsilon-caprolactone] and its self-assembly into polymeric vesicles employing the solvent shift method. In this way, well-defined core-shell structures suitable for encapsulation of drugs are generated. The hydrophobic polycaprolactone side-chain and the hydrophilic chitosan backbone are linked via an enzyme-cleavable peptide. The synthetic route involves the functionalization of chitosan with maleimide groups and the preparation of polycaprolactone with alkyne end-groups. A peptide functionalized with a thiol group on one side and an azide group on the other side is prepared. Thiol-ene click-chemistry and azide-alkyne Huisgen cycloaddition are then used to link the chitosan and poly-epsilon-caprolactone chains, respectively, with this peptide. For a preliminary study, poly-l-lysin is a readily available and cleavable peptide that is introduced to investigate the feasibility of the system. The size and shape of the polymersomes are studied by dynamic light scattering and cryo-scanning electron microscopy. Furthermore, degradability is studied by incubating the polymersomes with two enzymes, trypsin and chitosanase. A dispersion of polymersomes is used to coat titanium plates and to further test the stability against enzymatic degradation.
Nach einer Einführung in die Geschichte der Strategiespiele und im Speziellen von 4X-Spielen wird das Phänomen der „Hands-off-Games“ erläutert. Im Anschluss wird ein Vorschlag unterbreitet, wie 4X-Geschichtsspiele im Unterricht eingesetzt werden können. Dabei soll ein 4X-Strategiespiel zu einem historischen Thema entworfen werden. Die Modellierung erfolgt in drei Arbeitsschritten: Themenfindung, Modellfindung, Parametrierung. In den Entwurf des Modells fließen viele Überlegungen ein, die zentrale Fragen der Gemeinschaftskunde betreffen.
From dawn till dusk
(2020)
Supernova remnants are believed to be the source of cosmic rays with energies up to 10^15 eV that are produced within our Galaxy. The acceleration mechanism associated with the collision-less shocks in supernova remnants - diffusive shock acceleration - predicts a spectral index of the accelerated non-thermal particles of s = 2. However, measurements of non-thermal emission in radio, X-rays and gamma-rays reveal significant deviations of the particles spectral index from the canonical value of s = 2.
The youngest Galactic supernova remnant G1.9+0.3 is an interesting target for next-generation gamma-ray observatories. So far, the remnant is only detected in the radio and the X-ray bands, but its young age of ≈100 yrs and inferred shock speed of ≈ 14, 000 km/s could make it an efficient particle accelerator.
I performed spherical symmetric 1D simulations with the RATPaC code, in which I simultaneously solved the transport equation for cosmic rays, the transport equation for magnetic turbulence, and the hydro-dynamical equations for the gas flow. Separately computed distributions of the particles accelerated at the forward and the reverse shock were then used to calculate the spectra of synchrotron, inverse Compton, and Pion-decay radiation from the source.
The emission from G1.9+0.3 can be self-consistently explained within the test-particle limit. I find that the X-ray flux is dominated by emission from the forward shock while most of the radio emission originates near the reverse shock, which makes G1.9+0.3 the first remnant with non-thermal radiation detected from the reverse shock. The flux of very-high-energy gamma-ray emission from G1.9+0.3 is expected to be close to the sensitivity threshold of the Cherenkov Telescope Array. The limited time available to grow large-scale turbulence limits the maximum energy of particles to values below 100 TeV, hence G1.9+0.3 is not a PeVatron.
Although there are many models for the acceleration of cosmic rays in Supernova remnants, the escape of cosmic rays from these sources is yet understudied.
I use our time-dependent acceleration code RATPaC to study the acceleration of cosmic rays and their escape in post-adiabatic Supernova remnants and calculate the subsequent gamma-ray emission from inverse-Compton scattering and Pion decay. My simulations span 100,000 years, thus covering the free-expansion, the Sedov-Taylor, and the beginning of the post-adiabatic phase of the remnant’s evolution.
At later stages of the evolution cosmic rays over a wide range of energy can reside outside of the remnant, creating spectra that are softer than predicted by standard diffusive shock acceleration and feature breaks in the 10 - 100 GeV-range. The total spectrum of cosmic rays released into the interstellar medium has a spectral index of s ≈ 2.4 above roughly 10 GeV which is close to that required by Galactic propagation models. I further find the gamma-ray luminosity to peak around an age of 4,000 years for inverse-Compton-dominated high-energy emission. Remnants expanding in low-density media emit generally more inverse-Compton radiation matching the fact that the brightest known supernova remnants - RCW86, Vela Jr, HESSJ1721-347 and RXJ1713.7-3946 - are all expanding in low density environments.
The importance of feedback from the cosmic-rays on the hydrodynamical evolution of the remnants is debated as a possibility to obtain soft cosmic-ray spectra at low energies.
I performed spherically symmetric 1-D simulations with a modified version of the RATPaC code, in which I simultaneously solve the transport equation for cosmic rays and the hydrodynamical equations, including the back-reaction of the cosmic-ray pressure on the flow profiles.
Besides the known modification of the flow profiles and the consequently curved cosmic-ray spectra, steady-state models for non-linear diffusive shock acceleration overpredict the total compression ratio that can be reached with cosmic-ray feedback, as there is limited time for building these modifications. Further, I find modifications to the downstream flow structure that change the evolutionary behavior of the remnant and trigger a cosmic-ray-induced instability close to the contact discontinuity, if and when the cosmic-ray pressure becomes dominant there.
Starch and Glycogen Analyses
(2020)
For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included
Envy is an unpleasant emotion. If individuals anticipate that comparing their payoff with the (potentially higher) payoff of others will make them envious, they may want to actively avoid information about other people’s payoffs. Given the opportunity to reduce another person’s payoff, an individual’s envy may trigger behavior that is detrimental to welfare. In this case, if individuals anticipate that they will react in a welfare-reducing way, they may also avoid information about other people’s payoffs from the outset. We investigated these two hypotheses using three experiments. We found that 13% of our potentially envious subjects avoided information when they did not have the opportunity to reduce another participant’s payoff. Psychological scales do not explain this behavior. We also found that voluntarily uninformed subjects did neither deduct less of the payoff nor less frequently than subjects who could not avoid the information.
Stochastic uncertainty can cause difficult coordination problems that may hinder mutually beneficial cooperation. We propose a mechanism of ex-post voluntary transfers designed to circumvent these coordination problems and ask whether it can do so. To test this, we implement a controlled laboratory experiment based on a repeatedly played Ultimatum Game with a stochastic endowment. Contrary to our hypothesis, we find that allowing voluntary transfers does not entail an efficiency increase. We suggest and analyze two main reasons for this finding: First, the stochastic uncertainty forces proposers to accept high strategic uncertainty if they intend to cooperate by claiming a low amount (which many proposers do not). Second, many responders behave only incompletely conditionally cooperative by transferring too little (which hinders cooperation in future periods).
Europa Universalis IV
(2020)
The WTO’s Crisis
(2020)
The perception of the WTO is currently one of an organisation in crisis. Yet, appraisal varies regarding its extent and seriousness: Is it merely a rough time or are we standing on the edge of destruction? The article will trace developments inside as well as outside the WTO in order to assess the magnitude of the crisis. It will be argued that while certain developments inside the organisation, when seen in accumulation would already warrant serious attention, only together with developments taking place outside of the WTO, the two strands of developments unfold their full potential for the crisis. The overall situation renders the WTO in a difficult position, as it is currently unable to adapt to these challenges, while keeping calm and carrying on might similarly further the crisis. While States might improve and further develop their trade relations in bi- and plurilateral agreements, it is only the WTO that reflects and stands for the multilateral post (cold) war order.
In nature, plants are often subjected to periods of recurrent environmental stress that can strongly affect their development and productivity. To cope with these conditions, plants can remember a previous stress, which allows them to respond more efficiently to a subsequent stress, a phenomenon known as priming. This ability can be maintained at the somatic level for a few days or weeks after the stress is perceived, suggesting that plants can store information of a past stress during this recovery phase. While the immediate responses to a single stress event have been extensively studied, knowledge on priming effects and how stress memory is stored is still scarce. At the molecular level, memory of a past condition often involves changes in chromatin structure and organization, which may be maintained independently from transcription. In this review, we will summarize the most recent developments in the field and discuss how different levels of chromatin regulation contribute to priming and plant abiotic stress memory.
Dans cette étude, on établira une relation sémantique entre les catégories TAM, c’est-à-dire, on verra comment la temporalité, l’aspectualité et la modalité interagissent ou se recoupent entre elles. D’abord, les catégories TAM seront étudiées sous une approche sémantique-fonctionnelle et puis – du point de vue pragmatique – quelques moyens linguistiques de ses expressions, comme l’imparfait et le futur qui n’expriment pas seulement des valeurs temporelles et aspectuelles, mais aussi des valeurs modales ou comme le verbe modal devoir qui en plus de sa valeur modale peut aussi exprimer la temporalité seront analysés quant à leurs interactions avec d’autres éléments présents dans l’énoncé, comme les adverbes (temporels et modaux) et les modes d’action.
Scholars have long recognised the importance of contexts of reception in shaping the integration of immigrants and refugees in a host society. Studies of refugees, in particular, have examined groups where the different dimensions of reception (government, labour market, and ethnic community) have been largely positive. How important is this merging of positive contexts across dimensions of reception? We address this through a comparative study of Vietnamese refugees to West Germany beginning in 1979 and contract workers to East Germany beginning in 1980. These two migration streams converged when Germany reunified in 1990. Drawing on mixed qualitative methods, this paper offers a strategic case for understanding factors that shape the resettlement experiences of Vietnamese refugees and immigrants in Germany. By comparing two migration streams from the same country of origin, but with different backgrounds and contexts of reception, we suggest that ethnic networks may, in time, offset the disadvantages of a negative government reception.
Humboldts Eskorte
(2020)
Auf seiner Russlandexpedition von 1829 wurde Alexander von Humboldt fast durchgängig von Sicherheitskräften der Regierung begleitet. Die Forschung wies dieser Eskorte bisher vor allem eine Kontrollfunktion zu. Im Folgenden wird gezeigt, dass Humboldts bewaffnete Begleiter wahrscheinlich weniger der Überwachung, als der Absicherung seiner Expedition dienten. Der Artikel wirft dafür einen Blick auf die Sicherheitslage im Umfeld der Russlandreise, die Eskorte an sich sowie ihre letztendlich eng begrenzten Möglichkeiten zur Kontrolle des Wissenschaftlers. An Material stehen dafür unter anderem Humboldts Reisekorrespondenz, der Reisebericht seines Gefährten Gustav Rose und die erst jüngst veröffentlichten Tagebücher Christian Gottfried Ehrenbergs zur Verfügung.
Im Rahmen der vom Bundesministerium für Bildung und -forschung geförderten Forschungsinitiative „BonaRes – Boden als nachhaltige Ressource der Bioökonomie“ soll sich das Teilprojekt „I4S – integrated system for site-specific soil fertility management“ der Entwicklung eines integrierten Systems zum ortsspezifischen Management der Bodenfruchtbarkeit widmen. Hierfür ist eine Messplattform zur Bestimmung relevanter Bodeneigenschaften und der quantitativen Analyse ausgewählter Makro- und Mikronährstoffe geplant. In der ersten Phase dieses Projekts liegt das Hauptaugenmerk auf der Kalibrierung und Validierung der verschiedenen Sensoren auf die Matrix Boden, der Probennahme auf dem Acker und der Planung sowie dem Aufbau der Messplattform. Auf dieser Plattform sollen in der zweiten Phase des Projektes die verschiedenen Bodensensoren installiert, sowie Modelle und Entscheidungsalgorithmen zur Steuerung der Düngung und dementsprechend Verbesserung der Bodenfunktionen erstellt werden.
Ziel der vorliegenden Arbeit ist die Grundlagenuntersuchung und Entwicklung einer robusten Online-Analyse mittels Energie-dispersiver Röntgenfluoreszenzspektroskopie (EDRFA) zur Quantifizierung ausgewählter Makro- und Mikronährstoffe in Böden für eine kostengünstige und flächendeckende Kartierung von Ackerflächen. Für die Entwicklung eines Online-Verfahrens wurde ein dem Stand der Technik entsprechender Röntgenfluoreszenzmesskopf in Betrieb genommen und die dazugehörigen Geräteparameter auf die Matrix Boden optimiert. Die Bestimmung der analytischen Qualitäts-merkmale wie Präzision und Nachweisgrenzen fand für eine Auswahl an Nährelementen von Aluminium bis Zink statt. Um eine möglichst Matrix-angepasste Kalibrierung zu erhalten, wurde sowohl mit zertifizierten Referenzmaterialien (CRM), als auch mit Ackerböden kalibriert. Da einer der größten Nachteile der Röntgenfluoreszenzanalyse die Beeinflussung durch Matrixeffekte ist, wurde neben der klassischen univariaten Datenauswertung auch die chemometrische multivariate Methode der Partial Least Squares Regression (PLSR) eingesetzt. Die PLSR bietet dabei den Vorteil, Matrixeffekte auszugleichen, wodurch robustere Kalibriermodelle erhalten werden können. Zusätzlich wurde eine Hauptkomponentenanalyse (PCA) durchgeführt, um Gemeinsamkeiten und Ausreißer innerhalb des Probensets zu identifizieren. Es zeigte sich, dass eine Klassifizierung der Böden anhand ihrer Textur Sand, Schluff, Lehm und Ton möglich ist.
Aufbauend auf den Ergebnissen idealer Bodenproben (zu Tabletten gepresste luftgetrocknete Proben mit Korngrößen < 0,5 mm) wurde im Verlauf dieser Arbeit die Probenvorbereitung immer weiter reduziert und der Einfluss verschiedener Kenngrößen untersucht. Diese Einflussfaktoren können die Dichte und die Homogenität der Probe, sowie Korngrößeneffekte und die Feuchtigkeit sein. Anhand des RMSE (Wurzel der mittleren Fehlerquadratsumme) und unter Berücksichtigung der Residuen werden die jeweils erstellten Kalibriermodelle miteinander verglichen. Um die Güte der Modelle zu bewerten, wurden diese mit einem Testset validiert. Hierfür standen 662 Bodenproben von 15 verschiedenen Standorten in Deutschland zur Verfügung. Da die Ergebnisse an gepressten Tabletten für die Elemente Al, Si, K, Ca, Ti, Mn, Fe und Zn den Anforderungen für eine spätere Online-Analyse entsprechen, wurden im weiteren Verlauf dieser Arbeit Kalibriermodelle mit losen Bodenproben erstellt. Auch hier konnten gute Ergebnisse durch ausreichende Nachweisgrenzen und eine niedrige gemittelte Messabweichung bei der Vorhersage unbekannter Testproben erzielt werden. Es zeigte sich, dass die Vorhersagefähigkeit mit der multivariaten PLSR besser ist als mit der univariaten Datenauswertung, insbesondere für die Elemente Mn und Zn.
Der untersuchte Einfluss der Feuchtigkeit und der Korngrößen auf die Quantifizierung der Elementgehalte war vor allem bei leichteren Elementen deutlich zu sehen. Es konnte schließlich eine multivariate Kalibrierung unter Berücksichtigung dieser Faktoren für die Elemente Al bis Zn erstellt werden, so dass ein Einsatz an Böden auf dem Acker möglich sein sollte. Eine höhere Messunsicherheit muss dabei einkalkuliert werden. Für eine spätere Probennahme auf dem Feld wurde zudem der Unterschied zwischen statischen und dynamischen Messungen betrachtet, wobei sich zeigte, dass beide Varianten genutzt werden können. Zum Abschluss wurde der hier eingesetzte Sensor mit einem kommerziell erhältlichen Hand-Gerät auf sein Quantifizierungspotential hin verglichen. Der Sensor weist anhand seiner Ergebnisse ein großes Potential als Online-Sensor für die Messplattform auf. Die Ergebnisse unter Laborbedingungen zeigen, dass eine robuste Analyse Ackerböden unter Berücksichtigung der Einflussfaktoren möglich ist.
According to established understanding, deep-water formation in the North Atlantic and Southern Ocean keeps the deep ocean cold, counter-acting the downward mixing of heat from the warmer surface waters in the bulk of the world ocean. Therefore, periods of strong Atlantic meridional overturning circulation (AMOC) are expected to coincide with cooling of the deep ocean and warming of the surface waters. It has recently been proposed that this relation may have reversed due to global warming, and that during the past decades a strong AMOC coincides with warming of the deep ocean and relative cooling of the surface, by transporting increasingly warmer waters downward. Here we present multiple lines of evidence, including a statistical evaluation of the observed global mean temperature, ocean heat content, and different AMOC proxies, that lead to the opposite conclusion: even during the current ongoing global temperature rise a strong AMOC warms the surface. The observed weakening of the AMOC has therefore delayed global surface warming rather than enhancing it.
Social Media Abstract:
The overturning circulation in the Atlantic Ocean has weakened in response to global warming, as predicted by climate models. Since it plays an important role in transporting heat, nutrients and carbon, a slowdown will affect global climate processes and the global mean temperature. Scientists have questioned whether this slowdown has worked to cool or warm global surface temperatures. This study analyses the overturning strength and global mean temperature evolution of the past decades and shows that a slowdown acts to reduce the global mean temperature. This is because a slower overturning means less water sinks into the deep ocean in the subpolar North Atlantic. As the surface waters are cold there, the sinking normally cools the deep ocean and thereby indirectly warms the surface, thus less sinking implies less surface warming and has a cooling effect. For the foreseeable future, this means that the slowing of the overturning will likely continue to slightly reduce the effect of the general warming due to increasing greenhouse gas concentrations.
We analyze workers’ risk preferences and training investments. Our conceptual framework differentiates between the investment risk and insurance mechanisms underpinning training decisions. Investment risk leads risk-averse workers to train less; they undertake more training if it insures them against future losses. We use the German Socio-Economic Panel (SOEP) to demonstrate that risk affinity is associated with more training, implying that, on average, investment risks dominate the insurance benefits of training. Crucially, this relationship is evident only for general training; there is no relationship between risk attitudes and specific training. Thus, as expected, risk preferences matter more when skills are transferable – and workers have a vested interest in training outcomes – than when they are not. Finally, we provide evidence that the insurance benefits of training are concentrated among workers with uncertain employment relationships or limited access to public insurance schemes.
Drinking is Different!
(2020)
Unhealthy behavior can be extremely costly from a micro- and macroeconomic perspective and exploring the determinants of such behavior is highly important from an economist’s point of view. We examine whether locus of control (LOC) can explain alcohol consumption as an important domain of health behavior. LOC measures how much an individual believes that she is in control of the consequences of her own actions for her life’s future outcomes. While earlier literature showed that an increasing internal LOC is associated with increased health-conscious behavior in domains such as smoking, exercise or diets, we find that drinking seems to be different. Using German panel data from the Socio-Economic Panel (SOEP) we find a significant positive effect of having an internal LOC on the probability of moderate and regular drinking. We suggest and discuss two likely mechanisms for this relationship and find interesting gender differences. While social investments play an important role for both men and women, risk perceptions are especially relevant for men.
Labor market policy tools such as training and sanctions are commonly used to help bring workers back to work. By analogy to medical treatments, the individual exposure to these tools may have side effects. We study effects on health using individual-level population registers on labor market events outcomes, drug prescriptions and sickness absence, comparing outcomes before and after exposure to training and sanctions. We find that training improves cardiovascular and mental health and lowers sickness absence. The results suggest that this is not due to improved employment prospects but rather to instantaneous features of participation such as, perhaps, the adoption of a more rigorous daily routine. Unemployment benefits sanctions cause a short-run deterioration of mental health, possibly due higher stress levels, but this tapers out quickly.
Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeastern Asia, 42-75 degrees N, 50-180 degrees E). Pollen data were taxonomically harmonized, i.e. the original 437 taxa were assigned to 106 combined pollen taxa. Age-depth models for all records were revised by applying a constant Bayesian age-depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples), with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 ka (calibrated thousands of years before 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area, with the exception of the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, PANGAEA) and 10 % were contributions by the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have >= 3 dates, allowing the establishment of reliable chronologies. The dataset can be used for various purposes, including pollen data mapping (example maps for Larix at selected time slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.org/10.1594/PANGAEA.898616 (Cao et al., 2019a), also including the site information, data source, original publication, dating data, and the plant functional type for each pollen taxa.
In the last decade the photovoltaic research has been preponderantly overturned by the arrival of metal halide perovskites. The introduction of this class of materials in the academic research for renewable energy literally shifted the focus of a large number of research groups and institutions. The attractiveness of halide perovskites lays particularly on their skyrocketing efficiencies and relatively simple and cheap fabrication methods. Specifically, the latter allowed for a quick development of this research in many universities and institutes around the world at the same time. The outcome has been a fast and beneficial increase in knowledge with a consequent terrific improvement of this new technology. On the other side, the enormous amount of research promoted an immense outgrowth of scientific literature, perpetually published. Halide perovskite solar cells are now effectively competing with other established photovoltaic technologies in terms of power conversion efficiencies and production costs. Despite the tremendous improvement, a thorough understanding of the energy losses in these systems is of imperative importance to unlock the full thermodynamic potential of this material. This thesis focuses on the understanding of the non-radiative recombination processes in the neat perovskite and in complete devices. Specifically, photoluminescence quantum yield (PLQY) measurements were applied to multilayer stacks and cells under different illumination conditions to accurately determine the quasi-Fermi levels splitting (QFLS) in the absorber, and compare it with the external open-circuit voltage of the device (V_OC). Combined with drift-diffusion simulations, this approach allowed us to pinpoint the sites of predominant recombination, but also to investigate the dynamics of the underlying processes. As such, the internal and external ideality factors, associated to the QFLS and V_OC respectively, are studied with the aim of understanding the type of recombination processes taking place in the multilayered architecture of the device. Our findings highlight the failure of the equality between QFLS and V_OC in the case of strong interface recombination, as well as the detrimental effect of all commonly used transport layers in terms of V_OC losses. In these regards, we show how, in most perovskite solar cells, different recombination processes can affect the internal QFLS and the external V_OC and that interface recombination dictates the V_OC losses. This line of arguments allowed to rationalize that, in our devices, the external ideality factor is completely dominated by interface recombination, and that this process can alone be responsible for values of the ideality factor between 1 and 2, typically observed in perovskite solar cells. Importantly, our studies demonstrated how strong interface recombination can lower the ideality factor towards values of 1, often misinterpreted as pure radiative second order recombination. As such, a comprehensive understanding of the recombination loss mechanisms currently limiting the device performance was achieved. In order to reach the full thermodynamic potential of the perovskite absorber, the interfaces of both the electron and hole transport layers (ETL/HTL) must be properly addressed and improved. From here, the second part of the research work is devoted on reducing the interfacial non-radiative energy losses by optimizing the structure and energetics of the relevant interface in our solar cell devices, with the aim of bringing their quasi-Fermi level splitting closer to its radiative limit. As such, the interfaces have been carefully addressed and optimized with different methodologies. First, a small amount of Sr is added into the perovskite precursor solution with the effect of effectively reducing surface and interface recombination. In this case, devices with V_OC up to 1.23 V were achieved and the energy losses were minimized to as low as 100 meV from the radiative limit of the material. Through a combination of different methods, we showed that these improvements are related to a strong n-type surface doping, which repels the holes in the perovskite from the surface and the interface with the ETL. Second, a more general device improvement was achieved by depositing a defect-passivating poly(ionic-liquid) layer on top of the perovskite absorber. The resulting devices featured a concomitant improvement of the V_OC and fill factor, up to 1.17 V and 83% respectively, reaching efficiency as high as 21.4%. Moreover, the protecting polymer layer helped to enhance the stability of the devices under prolonged maximum power point tracking measurements. Lastly, PLQY measurements are used to investigate the recombination mechanisms in halide-segregated large bandgap perovskite materials. Here, our findings showed how few iodide-rich low-energy domains act as highly efficient radiative recombination centers, capable of generating PLQY values up to 25%. Coupling these results with a detailed microscopic cathodoluminescence analysis and absorption profiles allowed to demonstrate how the emission from these low energy domains is due to the trapping of the carriers photogenerated in the Br-rich high-energy domains. Thereby, the strong implications of this phenomenon are discussed in relation to the failure of the optical reciprocity between absorption and emission and on the consequent applicability of the Shockley-Queisser theory for studying the energy losses such systems. In conclusion, the identification and quantification of the non-radiative QFLS and V_OC losses provided a base knowledge of the fundamental limitation of perovskite solar cells and served as guidance for future optimization and development of this technology. Furthermore, by providing practical examples of solar cell improvements, we corroborated the correctness of our fundamental understanding and proposed new methodologies to be further explored by new generations of scientists.
Conventional wisdom holds that large sums of money poured into election campaigns are the gateway to corruption. Allegations of the corrupting influence of money in politics and policy are widespread on the national level. Yet, little empirical evidence has advanced the understanding of such a link on the local level, coupled with blurred corruption measures. This master’s thesis tests the effect of campaign finance on public procurement corruption risks in Colombian municipalities, focusing on donations, small donations, and financial disclosure. To that end, I seized publicly disclosed contribution-level data from the 2015 municipal elections and a novel index of institutionalized public procurement corruption risks based upon contract-level data from the near population of local governments. The analysis shows that donations are negatively associated with overall corruption risk, yet they affect specific corruption risks differently. By contrast, small donations seem to correlate positively with direct awarding for a sub-sample of medium-sized municipalities, whereas in their large-sized counterparts the effect of the former on institutionalized corruption is adverse. Finally, financial misreporting is positively linked with market competition restrictions and direct awarding. In the conclusion, I discuss the implications of these findings for future research and outline a series of policy recommendations.
There is ample evidence that youth resistance training (RT) is safe, joyful, and effective for different markers of performance (e.g., muscle strength, power, linear sprint speed) and health (e.g., injury prevention). Accordingly, the first aim of this narrative review is to present and discuss the relevance of muscle strength for youth physical development. The second purpose is to report evidence on the effectiveness of RT on muscular fitness (muscle strength, power, muscle endurance), on movement skill performance and injury prevention in youth. There is evidence that RT is effective in enhancing measures of muscle fitness in children and adolescents, irrespective of sex. Additionally, numerous studies indicate that RT has positive effects on fundamental movement skills (e.g., jumping, running, throwing) in youth regardless of age, maturity, training status, and sex. Further, irrespective of age, sex, and training status, regular exposure to RT (e.g., plyometric training) decreases the risk of sustaining injuries in youth. This implies that RT should be a meaningful element of youths’ exercise programming. This has been acknowledged by global (e.g., World Health Organization) and national (e.g., National Strength and Conditioning Association) health- and performance-related organizations which is why they recommended to perform RT as an integral part of weekly exercise programs to promote muscular strength, fundamental movement skills, and to resist injuries in youth.
Most reading theories assume that readers aim at word centers for optimal information processing. During reading, saccade targeting turns out to be imprecise: Saccades’ initial landing positions often miss the word centers and have high variance, with an additional systematic error that is modulated by the distance from the launch site to the center of the target word. The performance of the oculomotor system, as reflected in the statistics of within-word landing positions, turns out to be very robust and mostly affected by the spatial information during reading. Hence, it is assumed that the saccade generation is highly automated.
The main goal of this thesis is to explore the performance of the oculomotor system under various reading conditions where orthographic information and the reading direction were manipulated. Additionally, the challenges in understanding the eye movement data to represent the oculomotor process during reading are addressed.
Two experimental studies and one simulation study were conducted for this thesis, which resulted in the following main findings:
(i) Reading texts with orthographic manipulations leads to specific changes in the eye movement patterns, both in temporal and spatial measures. The findings indicate that the oculomotor control of eye movements during reading is dependent on reading conditions (Chapter 2 & 3).
(ii) Saccades’ accuracy and precision can be simultaneously modulated under reversed reading condition, supporting the assumption that the random and systematic oculomotor errors are not independent. By assuming that readers increase the precision of sensory observation while maintaining the learned prior knowledge when reading direction was reversed, a process-oriented Bayesian model for saccade targeting can account for the simultaneous reduction of oculomotor errors (Chapter 2).
(iii) Plausible parameter values serving as proxies for the intended within-word landing positions can be estimated by using the maximum a posteriori estimator from Bayesian inference. Using the mean value of all observations as proxies is insufficient for studies focusing on the launch-site effect because the method exhibits the strongest bias when estimating the size of the effect. Mislocated fixations remain a challenge for the currently known estimation methods, especially when the systematic oculomotor error is large (Chapter 4).
The results reported in this thesis highlight the role of the oculomotor system, together with underlying cognitive processes, in eye movements during reading. The modulation of oculomotor control can be captured through a precise analysis of landing positions.
The interplay between cognitive and oculomotor processes during reading can be explored when the spatial layout of text deviates from the typical display. In this study, we investigate various eye-movement measures during reading of text with experimentally manipulated layout (word-wise and letter-wise mirrored-reversed text as well as inverted and scrambled text). While typical findings (e.g., longer mean fixation times, shorter mean saccades lengths) in reading manipulated texts compared to normal texts were reported in earlier work, little is known about changes of oculomotor targeting observed in within-word landing positions under the above text layouts. Here we carry out precise analyses of landing positions and find substantial changes in the so-called launch-site effect in addition to the expected overall slow-down of reading performance. Specifically, during reading of our manipulated text conditions with reversed letter order (against overall reading direction), we find a reduced launch-site effect, while in all other manipulated text conditions, we observe an increased launch-site effect. Our results clearly indicate that the oculomotor system is highly adaptive when confronted with unusual reading conditions.
In den letzten Jahrzehnten ist die Nachfrage nach kostengünstigen und flächendeckenden Kartierungsmöglichkeiten im Hinblick auf eine ertragssteigernde und umweltfreundlichere Bewirtschaftung von landwirtschaftlichen Nutzflächen stark gestiegen. Hierfür eignen sich spektroskopische Methoden wie die Röntgenfluoreszenzanalyse (RFA), Raman- und Gammaspektroskopie sowie die laserinduzierte Plasmaspektroskopie (LIBS). In Abhängigkeit von der Funktionsweise der jeweiligen Methoden werden Informationen zu verschiedensten Bodeneigenschaften wie Nährelementgehalt, Textur und pH-Wert erhalten.
Ziel dieser Arbeit ist die Entwicklung eines Online-LIBS-Verfahrens zur Nährelementbestimmmung und Kartierung von Ackerflächen. Die LIBS ist eine schnelle und simultane Multielementanalyse bei der durch das Fokussieren eines hochenergetischen Laserpulses Probenmaterial von der Probenoberfläche ablatiert wird und in ein Plasma überführt wird. Beim Abkühlen des Plasmas wird Strahlung emittiert, welche Rückschlüsse über die elementare Zusammensetzung der Probe gibt. Diese Arbeit ist im Teilprojekt I4S (Intelligenz für Böden) im Forschungsprogramm BonaRes (Boden als nachhaltige Ressource für die Bioökonomie) des Bundesministerium für Bildung und Forschung (BMBF) entstanden. Es wurden insgesamt 651 Bodenproben von verschiedenen Test-Agrarflächen unterschiedlichster Standorte Deutschlands gemessen, ausgewertet und zu Validierungszwecken mit entsprechender Referenzanalytik wie die Optische Emissionsspektroskopie mittels induktiv gekoppeltem Plasma (ICP-OES) und die wellenlängendispersive Röntgenfluoreszenzanalyse (WDRFA) charakterisiert.
Für die Quantifizierung wurden zunächst die Messparameter des LIBS-Systems auf die Bodenmatrix optimiert und für die Elemente geeignete Linien ausgewählt sowie deren Nachweisgrenzen bestimmt. Es hat sich gezeigt, dass eine absolute Quantifizierung basierend auf einem univariaten Ansatz aufgrund der starken Matrixeffekte und der schlechten Reproduzierbarkeit des Plasmas nur eingeschränkt möglich ist. Bei Verwendung eines multivariaten Ansatz wie der Partial Least Squares Regression (PLSR) für die Kalibrierung konnten für die Nährelemente im Vergleich zur univariaten Variante Analyseergebnisse mit höherer Güte und geringeren Messunsicherheiten ermittelt werden. Die Untersuchungen haben gezeigt, dass das multivariate Modell weiter verbessert werden kann, indem mit einer Vielzahl von gut analysierten Böden verschiedener Standorte, Bodenarten und einem breiten Gehaltsbereich kalibriert wird. Mithilfe der Hauptkomponentenanalyse (PCA) wurde eine Klassifizierung der Böden nach der Textur realisiert. Weiterhin wurde auch eine Kalibrierung mit losem Bodenmaterial erstellt. Trotz der Signalabnahme konnten für die verschiedenen Nährelemente Kalibriergeraden mit ausreichender, analytischer Güte erstellt werden.
Für den Einsatz auf dem Acker wurde außerdem der Einfluss von Korngröße und Feuchtigkeit auf das LIBS-Signal untersucht. Die unterschiedlichen Korngrößen haben nur einen geringen Einfluss auf das LIBS-Signal und das Kalibriermodell lässt sich durch entsprechende Proben leicht anpassen. Dagegen ist der Einfluss der Feuchtigkeit deutlich stärker und hängt stark von der Bodenart ab, sodass für jede Bodenart ein separates Kalibriermodell für verschiedene Feuchtigkeitsgehalte erstellt werden muss. Mithilfe der PCA kann der Feuchtigkeitsgehalt im Boden grob abgeschätzt werden und die entsprechende Kalibrierung ausgewählt werden.
Diese Arbeit liefert essentielle Informationen für eine Echtzeit-Analyse von Nährelementen auf dem Acker mittels LIBS und leistet einen wichtigen Beitrag zu einer fortschrittlichen und zukunftsfähigen Nutzung von Ackerflächen.
Pavlovian-to-instrumental transfer (PIT) tasks examine the influence of Pavlovian stimuli on ongoing instrumental behaviour. Previous studies reported associations between a strong PIT effect, high-risk drinking and alcohol use disorder. This study investigated whether susceptibility to interference between Pavlovian and instrumental control is linked to risky alcohol use in a community sample of 18-year-old male adults. Participants (N = 191) were instructed to 'collect good shells' and 'leave bad shells' during the presentation of appetitive (monetary reward), aversive (monetary loss) or neutral Pavlovian stimuli. We compared instrumental error rates (ER) and functional magnetic resonance imaging (fMRI) brain responses between the congruent and incongruent conditions, as well as among high-risk and low-risk drinking groups. On average, individuals showed a substantial PIT effect, that is, increased ER when Pavlovian cues and instrumental stimuli were in conflict compared with congruent trials. Neural PIT correlates were found in the ventral striatum and the dorsomedial and lateral prefrontal cortices (lPFC). Importantly, high-risk drinking was associated with a stronger behavioural PIT effect, a decreased lPFC response and an increased neural response in the ventral striatum on the trend level. Moreover, high-risk drinkers showed weaker connectivity from the ventral striatum to the lPFC during incongruent trials. Our study links interference during PIT to drinking behaviour in healthy, young adults. High-risk drinkers showed higher susceptibility to Pavlovian cues, especially when they conflicted with instrumental behaviour, indicating lower interference control abilities. Increased activity in the ventral striatum (bottom-up), decreased lPFC response (top-down), and their altered interplay may contribute to poor interference control in the high-risk drinkers.
The higher education structure in Malaysia has experienced significant changes since the implementation of the Private Higher Educational Institutions Act of 1996. The unprecedented expansion of the higher education sector and the increasing autonomy conferred to universities have created a huge demand for competent university leadership that supports the development of higher education in Malaysia. This article discusses the very first national multiplication training in Malaysia in 2014 and analyses such out-comes as the identification of good practices for future initiatives and applications in university leadership training.
We investigate the initiation and early evolution of 12 solar eruptions, including six active-region hot channel and six quiescent filament eruptions, which were well observed by the Solar Dynamics Observatory, as well as by the Solar Terrestrial Relations Observatory for the latter. The sample includes one failed eruption and 11 coronal mass ejections, with velocities ranging from 493 to 2140 km s(-1). A detailed analysis of the eruption kinematics yields the following main results. (1) The early evolution of all events consists of a slow-rise phase followed by a main-acceleration phase, the height-time profiles of which differ markedly and can be best fit, respectively, by a linear and an exponential function. This indicates that different physical processes dominate in these phases, which is at variance with models that involve a single process. (2) The kinematic evolution of the eruptions tends to be synchronized with the flare light curve in both phases. The synchronization is often but not always close. A delayed onset of the impulsive flare phase is found in the majority of the filament eruptions (five out of six). This delay and its trend to be larger for slower eruptions favor ideal MHD instability models. (3) The average decay index at the onset heights of the main acceleration is close to the threshold of the torus instability for both groups of events (although, it is based on a tentative coronal field model for the hot channels), suggesting that this instability initiates and possibly drives the main acceleration.
What Colin Reynolds could tell us about nutrient limitation, N:P ratios and eutrophication control
(2020)
Colin Reynolds exquisitely consolidated our understanding of driving forces shaping phytoplankton communities and those setting the upper limit to biomass yield, with limitation typically shifting from light in winter to phosphorus in spring. Nonetheless, co-limitation is frequently postulated from enhanced growth responses to enrichments with both N and P or from N:P ranging around the Redfield ratio, concluding a need to reduce both N and P in order to mitigate eutrophication. Here, we review the current understanding of limitation through N and P and of co-limitation. We conclude that Reynolds is still correct: (i) Liebig's law of the minimum holds and reducing P is sufficient, provided concentrations achieved are low enough; (ii) analyses of nutrient limitation need to exclude evidently non-limiting situations, i.e. where soluble P exceeds 3-10 mu g/l, dissolved N exceeds 100-130 mu g/l and total P and N support high biomass levels with self-shading causing light limitation; (iii) additionally decreasing N to limiting concentrations may be useful in specific situations (e.g. shallow waterbodies with high internal P and pronounced denitrification); (iv) management decisions require local, situation-specific assessments. The value of research on stoichiometry and co-limitation lies in promoting our understanding of phytoplankton ecophysiology and community ecology.
Giant unilamellar vesicles are an important tool in todays experimental efforts to understand the structure and behaviour of biological cells. Their simple structure allows the isolation of the physical elastic properties of the lipid membrane. A central physical
property is the bending energy of the membrane, since the many different shapes of giant vesicles can be obtained by finding the minimum of the bending energy. In the spontaneous curvature model the bending energy is a function of the bending rigidity as well as the mean curvature and an additional parameter called the spontaneous curvature, which describes an internal preference of the lipid-bilayer to bend towards one side or the other. The spontaneous and mean curvature are local properties of the membrane.
Additional constraints arise from the conservation of the membrane surface area and the enclosed volume, which are global properties.
In this thesis the spontaneous curvature model is used to explain the experimental observation of a periodic shape oscillation of a giant unilamellar vesicle that was filled with a protein complex that periodically binds to and unbinds from the membrane.
By assuming that the binding of the proteins to the membrane induces a change in the spontaneous curvature the experimentally observed shapes could successfully be explained. This involves the numerical solution of the differential equations as obtained from the minimization of the bending energy respecting the area and volume constraints, the so called shape equations. Vice versa this approach can be used to estimate the spontaneous curvature from experimentally measurable quantities.
The second topic of this thesis is the analysis of concentration gradients in rigid conic membrane compartments. Gradients of an ideal gas due to gravity and gradients generated by the directed stochastic movement of molecular motors along a microtubulus were considered. It was possible to calculate the free energy and the bending energy analytically for the ideal gas. In the case of the non-equilibrium system with molecular motors, the characteristic length of the density profile, the jam-length, and its dependency on the opening angle of the conic compartment have been calculated in the mean-field limit.
The mean field results agree qualitatively with stochastic particle simulations.
Abdominal and general adiposity are independently associated with mortality, but there is no consensus on how best to assess abdominal adiposity. We compared the ability of alternative waist indices to complement body mass index (BMI) when assessing all-cause mortality. We used data from 352,985 participants in the European Prospective Investigation into Cancer and Nutrition (EPIC) and Cox proportional hazards models adjusted for other risk factors. During a mean follow-up of 16.1 years, 38,178 participants died. Combining in one model BMI and a strongly correlated waist index altered the association patterns with mortality, to a predominantly negative association for BMI and a stronger positive association for the waist index, while combining BMI with the uncorrelated A Body Shape Index (ABSI) preserved the association patterns. Sex-specific cohort-wide quartiles of waist indices correlated with BMI could not separate high-risk from low-risk individuals within underweight (BMI<18.5 kg/m(2)) or obese (BMI30 kg/m(2)) categories, while the highest quartile of ABSI separated 18-39% of the individuals within each BMI category, which had 22-55% higher risk of death. In conclusion, only a waist index independent of BMI by design, such as ABSI, complements BMI and enables efficient risk stratification, which could facilitate personalisation of screening, treatment and monitoring.
Obesity is a risk factor for several major cancers. Associations of weight change in middle adulthood with cancer risk, however, are less clear. We examined the association of change in weight and body mass index (BMI) category during middle adulthood with 42 cancers, using multivariable Cox proportional hazards models in the European Prospective Investigation into Cancer and Nutrition cohort. Of 241 323 participants (31% men), 20% lost and 32% gained weight (>0.4 to 5.0 kg/year) during 6.9 years (average). During 8.0 years of follow-up after the second weight assessment, 20 960 incident cancers were ascertained. Independent of baseline BMI, weight gain (per one kg/year increment) was positively associated with cancer of the corpus uteri (hazard ratio [HR] = 1.14; 95% confidence interval: 1.05-1.23). Compared to stable weight (+/- 0.4 kg/year), weight gain (>0.4 to 5.0 kg/year) was positively associated with cancers of the gallbladder and bile ducts (HR = 1.41; 1.01-1.96), postmenopausal breast (HR = 1.08; 1.00-1.16) and thyroid (HR = 1.40; 1.04-1.90). Compared to maintaining normal weight, maintaining overweight or obese BMI (World Health Organisation categories) was positively associated with most obesity-related cancers. Compared to maintaining the baseline BMI category, weight gain to a higher BMI category was positively associated with cancers of the postmenopausal breast (HR = 1.19; 1.06-1.33), ovary (HR = 1.40; 1.04-1.91), corpus uteri (HR = 1.42; 1.06-1.91), kidney (HR = 1.80; 1.20-2.68) and pancreas in men (HR = 1.81; 1.11-2.95). Losing weight to a lower BMI category, however, was inversely associated with cancers of the corpus uteri (HR = 0.40; 0.23-0.69) and colon (HR = 0.69; 0.52-0.92). Our findings support avoiding weight gain and encouraging weight loss in middle adulthood.
Ein Topos soll überprüft werden: ‚Spielerisch lernt es sich am besten.‘ Ist das wirklich so? Wo genau liegen die produktiven Übereinstimmungen zwischen ‚Spielen‘ und ‚Lernen‘? Wie kann man die Games-Kultur, die primär eine Unterhaltungskultur ist, für Konzepte des Lernens und der Bildung unter Bedingungen der Digitalität technischer Umgebungen (zurück-) gewinnen? Die allgegenwärtige Struktur des Spiels und des Spielens könnte einiges über die Logik des Lernens verraten.
Mit zunehmender Schnelligkeit etablieren sich neue Medien, Kommunikationsmittel und Kunstformen innerhalb unserer Gesellschaften. Oft sind es Jugendliche, die sich als „digital natives“ unbefangen auf diese Entwicklungen einlassen können. Der Ruf nach einem kritischen Umgang mit Medien, einer systematischen Medienerziehung und Medienbildung wird seit geraumer Zeit formuliert. Allerdings existieren bisher wenige Bemühungen die angehenden Pädagoginnen und Pädagogen mit entsprechenden Methoden, Ideen und Materialien auszustatten.
Der vorliegende Band der DIGAREC Series enthält Beiträge der interdisziplinären Ringvorlesung „Videospiele als didaktische Herausforderung“, die im Sommersemester 2017 an der Philosophischen Fakultät der Universität Potsdam durchgeführt wurde. Die Beiträge machen Vorschläge zum Einsatz von Computer- und Videospielen im schulischen Unterricht und für Aktivitäten in außerschulischen Jugendeinrichtungen. Die Autorinnen und Autoren erörtern aus den jeweiligen Perspektiven ihrer Fachdisziplinen konkrete Methoden und Anwendungsmöglichkeiten anhand von ausgewählten Computerspielen. Schwerpunkt des Interesses bilden dabei Videospiele, die in erster Linie zur Unterhaltung eingesetzt werden, da der Einsatz von „Serious Games“/“Educational Games“ in jüngster Zeit schon breiter wahrgenommen wird.
In recent years, a substantial number of psycholinguistic studies and of studies on acquired language impairments have investigated the case of morphologically complex words. These have provided evidence for what is known as ‘morphological decomposition’, i.e. a mechanism that decomposes complex words into their constituent morphemes during online processing. This is believed to be a fundamental, possibly universal mechanism of morphological processing, operating irrespective of a word’s specific properties.
However, current accounts of morphological decomposition are mostly based on evidence from suffixed words and compound words, while prefixed words have been comparably neglected. At the same time, it has been consistently observed that, across languages, prefixed words are less widespread than suffixed words. This cross-linguistic preference for suffixing morphology has been claimed to be grounded in language processing and language learning mechanisms. This would predict differences in how prefixed words are processed and therefore also affected in language impairments, challenging the predictions of the major accounts of morphological decomposition.
Against this background, the present thesis aims at reducing the gap between the accounts of morphological decomposition and the accounts of the suffixing preference, by providing a thorough empirical investigation of prefixed words. Prefixed words are examined in three different domains: (i) visual word processing in native speakers; (ii) visual word processing in non-native speakers; (iii) acquired morphological impairments. The processing studies employ the masked priming paradigm, tapping into early stages of visual word recognition. Instead, the studies on morphological impairments investigate the errors produced in reading aloud tasks.
As for native processing, the present work first focuses on derivation (Publication I), specifically investigating whether German prefixed derived words, both lexically restricted (e.g. inaktiv ‘inactive’) and unrestricted (e.g. unsauber ‘unclean’) can be efficiently decomposed. I then present a second study (Publication II) on a Bantu language, Setswana, which offers the unique opportunity of testing inflectional prefixes, and directly comparing priming with prefixed inflected primes (e.g. dikgeleke ‘experts’) to priming with prefixed derived primes (e.g. bokgeleke ‘talent’). With regard to non-native processing (Publication I), the priming effects obtained from the lexically restricted and unrestricted prefixed derivations in native speakers are additionally compared to the priming effects obtained in a group of non-native speakers of German. Finally, in the two studies on acquired morphological impairments, the thesis investigates whether prefixed derived words yield different error patterns than suffixed derived words (Publication III and IV).
For native speakers, the results show evidence for morphological decomposition of both types of prefixed words, i.e. lexically unrestricted and restricted derivations, as well as of prefixed inflected words. Furthermore, non-native speakers are also found to efficiently decompose prefixed derived words, with parallel results to the group of native speakers. I therefore conclude that, for the early stages of visual word recognition, the relative position of stem and affix in prefixed versus suffixed words does not affect how efficiently complex words are decomposed, either in native or in non-native processing. In the studies on acquired language impairments, instead, prefixes are consistently found to be more impaired than suffixes. This is explained in terms of a learnability disadvantage for prefixed words, which may cause weaker representations of the information encoded in affixes when these precede the stem (prefixes) as compared to when they follow it (suffixes). Based on the impairment profiles of the individual participants and on the nature of the task, this dissociation is assumed to emerge from later processing stages than those that are tapped into by masked priming. I therefore conclude that the different characteristics of prefixed and suffixed words do come into play at later processing stages, during which the lexical-semantic information contained in the different constituent morphemes is processed.
The findings presented in the four manuscripts significantly contribute to our current understanding of the mechanisms involved in processing prefixed words. Crucially, the thesis constrains the processing disadvantage for prefixed words to later processing stages, thereby suggesting that theories trying to establish links between language universals and processing mechanisms should more carefully consider the different stages involved in language processing and what factors are relevant for each specific stage.
Although a relatively large number of studies on acquired language impairments have tested the case of derivational morphology, none of these have specifically investigated whether there are differences in how prefixed and suffixed derived words are impaired. Based on linguistic and psycholinguistic considerations on prefixed and suffixed derived words, differences in how these two types of derivations are processed, and consequently impaired, are predicted. In the present study, we investigated the errors produced in reading aloud simple, prefixed, and suffixed words by three German individuals with agrammatic aphasia (NN, LG, SA). We found that, while NN and LG produced similar numbers of errors with prefixed and suffixed words, SA showed a selective impairment for prefixed words. Furthermore, NN and SA produced more errors specifically involving the affix with prefixed words than with suffixed words. We discuss our findings in terms of relative position of stem and affix in prefixed and suffixed words, as well as in terms of specific properties of prefixes and suffixes.
Droughts in tropical South America have an imminent and severe impact on the Amazon rainforest and affect the livelihoods of millions of people. Extremely dry conditions in Amazonia have been previously linked to sea surface temperature (SST) anomalies in the adjacent tropical oceans. Although the sources and impacts of such droughts have been widely studied, establishing reliable multi-year lead statistical forecasts of their occurrence is still an ongoing challenge. Here, we further investigate the relationship between SST and rainfall anomalies using a complex network approach. We identify four ocean regions which exhibit the strongest overall SST correlations with central Amazon rainfall, including two particularly prominent regions in the northern and southern tropical Atlantic. Based on the time-dependent correlation between SST anomalies in these two regions alone, we establish a new early-warning method for droughts in the central Amazon basin and demonstrate its robustness in hindcasting past major drought events with lead-times up to 18 months.
This paper addresses semantic/pragmatic variability of tag questions in German and makes three main contributions. First, we document the prevalence and variety of question tags in German across three different types of conversational corpora. Second, by annotating question tags according to their syntactic and semantic context, discourse function, and pragmatic effect, we demonstrate the existing overlap and differences between the individual tag variants. Finally, we distinguish several groups of question tags by identifying the factors that influence the speakers’ choices of tags in the conversational context, such as clause type, function, speaker/hearer knowledge, as well as conversation type and medium. These factors provide the limits of variability by constraining certain question tags in German against occurring in specific contexts or with individual functions.
Temporal variation of natural light sources such as airglow limits the ability of night light sensors to detect changes in small sources of artificial light (such as villages). This study presents a method for correcting for this effect globally, using the satellite radiance detected from regions without artificial light emissions. We developed a routine to define an approximate grid of locations worldwide that do not have regular light emission. We apply this method with a 5 degree equally spaced global grid (total of 2016 individual locations), using data from the Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB). This code could easily be adapted for other future global sensors. The correction reduces the standard deviation of data in the Earth Observation Group monthly DNB composites by almost a factor of two. The code and datasets presented here are available under an open license by GFZ Data Services, and are implemented in the Radiance Light Trends web application.
Using individual-based modeling to understand grassland diversity and resilience in the Anthropocene
(2020)
The world’s grassland systems are increasingly threatened by anthropogenic change. Susceptible to a variety of different stressors, from land-use intensification to climate change, understanding the mechanisms driving the maintenance of these systems’ biodiversity and stability, and how these mechanisms may shift under human-mediated disturbance, is thus critical for successfully navigating the next century. Within this dissertation, I use an individual-based and spatially-explicit model of grassland community assembly (IBC-grass) to examine several processes, thought key to understanding their biodiversity and stability and how it changes under stress. In the first chapter of my thesis, I examine the conditions under which intraspecific trait variation influences the diversity of simulated grassland communities. In the second and third chapters of my thesis, I shift focus towards understanding how belowground herbivores influence the stability of these grassland systems to either a disturbance that results in increased, stochastic, plant mortality, or eutrophication.
Intraspecific trait variation (ITV), or variation in trait values between individuals of the same species, is fundamental to the structure of ecological communities. However, because it has historically been difficult to incorporate into theoretical and statistical models, it has remained largely overlooked in community-level analyses. This reality is quickly shifting, however, as a consensus of research suggests that it may compose a sizeable proportion of the total variation within an ecological community and that it may play a critical role in determining if species coexist. Despite this increasing awareness that ITV matters, there is little consensus of the magnitude and direction of its influence. Therefore, to better understand how ITV changes the assembly of grassland communities, in the first chapter of my thesis, I incorporate it into an established, individual-based grassland community model, simulating both pairwise invasion experiments as well as the assembly of communities with varying initial diversities. By varying the amount of ITV in these species’ functional traits, I examine the magnitude and direction of ITV’s influence on pairwise invasibility and community coexistence. During pairwise invasion, ITV enables the weakest species to more frequently invade the competitively superior species, however, this influence does not generally scale to the community level. Indeed, unless the community has low alpha- and beta- diversity, there will be little effect of ITV in bolstering diversity. In these situations, since the trait axis is sparsely filled, the competitively inferior may suffer less competition and therefore ITV may buffer the persistence and abundance of these species for some time.
In the second and third chapters of my thesis, I model how one of the most ubiquitous trophic interactions within grasslands, herbivory belowground, influences their diversity and stability. Until recently, the fundamental difficulty in studying a process within the soil has left belowground herbivory “out of sight, out of mind.” This dilemma presents an opportunity for simulation models to explore how this understudied process may alter community dynamics. In the second chapter of my thesis, I implement belowground herbivory – represented by the weekly removal of plant biomass – into IBC-grass. Then, by introducing a pulse disturbance, modelled as the stochastic mortality of some percentage of the plant community, I observe how the presence of belowground herbivores influences the resistance and recovery of Shannon diversity in these communities. I find that high resource, low diversity, communities are significantly more destabilized by the presence of belowground herbivores after disturbance. Depending on the timing of the disturbance and whether the grassland’s seed bank persists for more than one season, the impact of the disturbance – and subsequently the influence of the herbivores – can be greatly reduced. However, because human-mediated eutrophication increases the amount of resources in the soil, thus pressuring grassland systems, our results suggest that the influence of these herbivores may become more important over time.
In the third chapter of my thesis, I delve further into understanding the mechanistic underpinnings of belowground herbivores on the diversity of grasslands by replicating an empirical mesocosm experiment that crosses the presence of herbivores above- and below-ground with eutrophication. I show that while aboveground herbivory, as predicted by theory and frequently observed in experiments, mitigates the impact of eutrophication on species diversity, belowground herbivores counterintuitively reduce biodiversity. Indeed, this influence positively interacts with the eutrophication process, amplifying its negative impact on diversity. I discovered the mechanism underlying this surprising pattern to be that, as the herbivores consume roots, they increase the proportion of root resources to root biomass. Because root competition is often symmetric, herbivory fails to mitigate any asymmetries in the plants’ competitive dynamics. However, since the remaining roots have more abundant access to resources, the plants’ competition shifts aboveground, towards asymmetric competition for light. This leads the community towards a low-diversity state, composed of mostly high-performance, large plant species. We further argue that this pattern will emerge unless the plants’ root competition is asymmetric, in which case, like its counterpart aboveground, belowground herbivory may buffer diversity by reducing this asymmetry between the competitively superior and inferior plants.
I conclude my dissertation by discussing the implications of my research on the state of the art in intraspecific trait variation and belowground herbivory, with emphasis on the necessity of more diverse theory development in the study of these fundamental interactions. My results suggest that the influence of these processes on the biodiversity and stability of grassland systems is underappreciated and multidimensional, and must be thoroughly explored if researchers wish to predict how the world’s grasslands will respond to anthropogenic change. Further, should researchers myopically focus on understanding central ecological interactions through only mathematically tractable analyses, they may miss entire suites of potential coexistence mechanisms that can increase the coviability of species, potentially leading to coexistence over ecologically-significant timespans. Individual-based modelling, therefore, with its focus on individual interactions, will prove a critical tool in the coming decades for understanding how local interactions scale to larger contexts, and how these interactions shape ecological communities and further predicting how these systems will change under human-mediated stress.
Adverse environmental conditions are detrimental to plant growth and development. Acclimation to abiotic stress conditions involves activation of signaling pathways which often results in changes in gene expression via networks of transcription factors (TFs). Mediator is a highly conserved co-regulator complex and an essential component of the transcriptional machinery in eukaryotes. Some Mediator subunits have been implicated in stress-responsive signaling pathways; however, much remains unknown regarding the role of plant Mediator in abiotic stress responses. Here, we use RNA-seq to analyze the transcriptional response of Arabidopsis thaliana to heat, cold and salt stress conditions. We identify a set of common abiotic stress regulons and describe the sequential and combinatorial nature of TFs involved in their transcriptional regulation. Furthermore, we identify stress-specific roles for the Mediator subunits MED9, MED16, MED18 and CDK8, and putative TFs connecting them to different stress signaling pathways. Our data also indicate different modes of action for subunits or modules of Mediator at the same gene loci, including a co-repressor function for MED16 prior to stress. These results illuminate a poorly understood but important player in the transcriptional response of plants to abiotic stress and identify target genes and mechanisms as a prelude to further biochemical characterization.
Many institutions struggle to tap into the potential of their large archives of radar reflectivity: these data are often affected by miscalibration, yet the bias is typically unknown and temporally volatile. Still, relative calibration techniques can be used to correct the measurements a posteriori. For that purpose, the usage of spaceborne reflectivity observations from the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) platforms has become increasingly popular: the calibration bias of a ground radar (GR) is estimated from its average reflectivity difference to the spaceborne radar (SR). Recently, Crisologo et al. (2018) introduced a formal procedure to enhance the reliability of such estimates: each match between SR and GR observations is assigned a quality index, and the calibration bias is inferred as a quality-weighted average of the differences between SR and GR. The relevance of quality was exemplified for the Subic S-band radar in the Philippines, which is greatly affected by partial beam blockage.
The present study extends the concept of quality-weighted averaging by accounting for path-integrated attenuation (PIA) in addition to beam blockage. This extension becomes vital for radars that operate at the C or X band. Correspondingly, the study setup includes a C-band radar that substantially overlaps with the S-band radar. Based on the extended quality-weighting approach, we retrieve, for each of the two ground radars, a time series of calibration bias estimates from suitable SR overpasses. As a result of applying these estimates to correct the ground radar observations, the consistency between the ground radars in the region of overlap increased substantially. Furthermore, we investigated if the bias estimates can be interpolated in time, so that ground radar observations can be corrected even in the absence of prompt SR overpasses. We found that a moving average approach was most suitable for that purpose, although limited by the absence of explicit records of radar maintenance operations.
En su breve visita a Canarias a finales del siglo XVIII, Alexander von Humboldt realizó interesantes observaciones sobre la geología de estas Islas. En relación con los fósiles inorgánicos, es decir, rocas y minerales, sus apreciaciones se enmarcan en sus estudios realizados en la Bergakademie de Freiberg, bajo la dirección de A. G. Werner, dentro del Neptunismo, y en sus experiencias en América e Italia. Aplicó en Canarias la universalidad de las formaciones geológicas wernerianas, algunas de las cuales creyó, erróneamente, haber observado en Tenerife, como la presencia de granitos o gneises. Humboldt estaba convencido de que el basalto
era de origen volcánico, y no se había formado por precipitación acuosa. Sería así uno de los más influyentes desertores del Neptunismo, y suscitó la visita a Canarias de numerosos geólogos a lo largo del siglo XIX.
Der Beitrag beschäftigt sich mit dem Potential von Computerspielen für den Politikunterricht. Im Mittelpunkt steht die Frage, ob sich die Politiksimulation DEMOCRACY 3 für einen Einsatz in der gymnasialen Oberstufe eignet. Es wird herausgearbeitet, dass sich die Spieler von DEMOCRACY 3 mit den Auswirkungen politischer Entscheidungen auf die ökonomische, soziale und kulturelle Lage eines westlichen Landes auseinandersetzen, während die Komplexität politischer Aushandlungs- und Entscheidungsprozesse in demokratischen Regierungssystemen nicht erfahrbar wird. Die hier festgestellte Unvollständigkeit der politischen Simulation wird für die pädagogische Praxis aber nicht nur als Problem, sondern vor allem auch als didaktische Chance gesehen. Denn es sind gerade die Leer- und Schwachstellen der Simulation des Spieles, die besondere Anknüpfungsmöglichkeiten für den Unterricht bieten, da sie eine kritische Analyse der Simulation bzw. einen Vergleich mit der Realität politischer Prozesse und damit eine tiefe Auseinandersetzung mit Politik im Allgemeinen herausfordern. Schließlich werden drei konkrete Ideen für die schulische Praxis vorgestellt.