Refine
Has Fulltext
- no (1889) (remove)
Year of publication
- 2017 (1889) (remove)
Document Type
- Article (1398)
- Doctoral Thesis (168)
- Other (118)
- Part of a Book (93)
- Review (52)
- Monograph/Edited Volume (46)
- Conference Proceeding (6)
- Habilitation Thesis (4)
- Journal/Publication series (2)
- Contribution to a Periodical (1)
Is part of the Bibliography
- yes (1889)
Keywords
- stars: massive (11)
- Germany (10)
- Holocene (9)
- German (8)
- climate change (8)
- stars: early-type (8)
- adolescence (7)
- stars: winds, outflows (7)
- Arabidopsis (6)
- Arabidopsis thaliana (6)
Institute
- Institut für Biochemie und Biologie (330)
- Institut für Geowissenschaften (254)
- Institut für Physik und Astronomie (251)
- Institut für Chemie (132)
- Department Psychologie (117)
- Department Sport- und Gesundheitswissenschaften (86)
- Institut für Ernährungswissenschaft (69)
- Department Linguistik (53)
- Institut für Mathematik (52)
- Institut für Romanistik (49)
How AAA(+) chaperones conformationally remodel specific target proteins in an ATP-dependent manner is not well understood. Here, we investigated the mechanism of the AAA(+) protein Rubisco activase (Rca) in metabolic repair of the photosynthetic enzyme Rubisco, a complex of eight large (RbcL) and eight small (RbcS) subunits containing eight catalytic sites. Rubisco is prone to inhibition by tight-binding sugar phosphates, whose removal is catalyzed by Rca. We engineered a stable Rca hexamer ring and analyzed its functional interaction with Rubisco. Hydrogen/deuterium exchange and chemical crosslinking showed that Rca structurally destabilizes elements of the Rubisco active site with remarkable selectivity. Cryo-electron microscopy revealed that Rca docks onto Rubisco over one active site at a time, positioning the C-terminal strand of RbcL, which stabilizes the catalytic center, for access to the Rca hexamer pore. The pulling force of Rca is fine-tuned to avoid global destabilization and allow for precise enzyme repair.
This article introduces a new theory, the Affective-Reflective Theory (ART) of physical inactivity and exercise. ART aims to explain and predict behavior in situations in which people either remain in a state of physical inactivity or initiate action (exercise). It is a dual-process model and assumes that exercise-related stimuli trigger automatic associations and a resulting automatic affective valuation of exercise (type-1 process). The automatic affective valuation forms the basis for the reflective evaluation (type-2 process), which can follow if self-control resources are available. The automatic affective valuation is connected with an action impulse, whereas the reflective evaluation can result in action plans. The two processes, in constant interaction, direct the individual towards or away from changing behavior. The ART of physical inactivity and exercise predicts that, when there is an affective-reflective discrepancy and self-control resources are low, behavior is more likely to be governed by the affective type-1 process. This introductory article explains the underlying concepts and main theoretical roots from which the ART of physical inactivity and exercise was developed (field theory, affective responses to exercise, automatic evaluation, evaluation-behavior link, dual-process theorizing). We also summarize the empirical tests that have been conducted to refine the theory in its present form.
Density dependence is of fundamental importance for population and range dynamics. Density-dependent reproduction of plants arises from competitive and facilitative plant-plant interactions that can be pollination independent or pollination mediated. In small and sparse populations, conspecific density dependence often turns from negative to positive and causes Allee effects. Reproduction may also increase with heterospecific density (community-level Allee effect), but the underlying mechanisms are poorly understood and the consequences for community dynamics can be complex. Allee effects have crucial consequences for the conservation of declining species, but also the dynamics of range edge populations. In invasive species, Allee effects may slow or stop range expansion. Observational studies in natural plant communities cannot distinguish whether reproduction is limited by pollination-mediated interactions among plants or by other neighbourhood effects (e.g. competition for abiotic resources). Even experimental pollen supply cannot distinguish whether variation in reproduction is caused by direct density effects or by plant traits correlated with density. Finally, it is unknown over which spatial scales pollination-mediated interactions occur. To circumvent these problems, we introduce a comprehensive experimental and analytical framework which simultaneously (1) manipulates pollen availability and quality by hand pollination and pollinator exclusion, (2) manipulates neighbourhoods by transplanting target plants, and (3) analyses the effects of con- and heterospecific neighbourhoods on reproduction with spatially explicit trait-based neighbourhood models. Synthesis. By manipulating both pollen availability and target plant locations within neighbourhoods, we can comprehensively analyse spatially explicit density dependence of plant reproduction. This experimental approach enhances our ability to understand the dynamics of sparse populations and of species geographical ranges.
From monthly mean observatory data spanning 1957-2014, geomagnetic field secular variation values were calculated by annual differences. Estimates of the spherical harmonic Gauss coefficients of the core field secular variation were then derived by applying a correlation based modelling. Finally, a Fourier transform was applied to the time series of the Gauss coefficients. This process led to reliable temporal spectra of the Gauss coefficients up to spherical harmonic degree 5 or 6, and down to periods as short as 1 or 2 years depending on the coefficient. We observed that a k(-2) slope, where k is the frequency, is an acceptable approximation for these spectra, with possibly an exception for the dipole field. The monthly estimates of the core field secular variation at the observatory sites also show that large and rapid variations of the latter happen. This is an indication that geomagnetic jerks are frequent phenomena and that significant secular variation signals at short time scales - i.e. less than 2 years, could still be extracted from data to reveal an unexplored part of the core dynamics.
Inside the EU Commission
(2017)
This article studies the perception of the EU Commission's Secretariat General in policy-making. Recently, research on EU institutions devotes increasing attention to analyzing structures and procedures of decision-making in EU institutions, most notably the EU Commission. Conventionally, the EU Commission is portrayed as a fragmented organization, divided along the lines of staff nationality, sectoral responsibilities and cabinets and General Directorates (DGs). The Secretariat General has long been viewed a weak actor that is hardly able or motivated to steer internal decision-making. However, recent research indicates a changing role of the Secretariat General as a pro-active broker and last arbiter. This article studies how the Secretariat General is perceived by the DGs in policy coordination and argues that this perception depends on the pattern of political authority, bureaucratic roles and the relevance and the alternatives prevailing in the policy field. The article is based on data from a survey among Commission officials.
Dem Text liegt ein Vortrag zugrunde, der auf dem 31. Motivationspsychologischen Kolloquium (MPK) in Heidelberg 2015 gehalten wurde. Im ersten Teil bietet er einen Überblick über die Motivationsforschung am Bochumer Heckhausen-Lehrstuhl in den 70er-Jahren („Bochumer Schule“). Dabei werden neben Heinz Heckhausen einzelne Mitarbeiter und ihre Schwerpunkte vorgestellt sowie das stimulierende Arbeitsklima an diesem Lehrstuhl beschrieben. Entsprechend der Vortragseinladung wird im Anschluss die Entwicklung der eigenen Forschungsschwerpunkte skizziert. Noch unter Heckhausens Leitung waren dies zunächst die Forschung zur Bezugsnormorientierung und die Einzelfallanalysen zur Lernmotivation mit dem Erweiterten Kognitiven Motivationsmodell. Danach geht der Vortrag auf Forschungsthemen ein, die dann in Heidelberg und Potsdam dazukamen. Hier geht es um die Erforschung von Tätigkeitsanreizen und um das Flow-Erleben. Abschließend wird der Potsdamer Versuch skizziert, herauszufinden, auf welche Weise unterschiedliche Motivationsqualitäten den Lernprozess und seine Resultate beeinflussen.
The invasion success of the cyanobacterium Cylindrospermopsis raciborskii in experimental mesocosms
(2017)
The potentially toxic, invasive cyanobacterium Cylindrospermopsis raciborskii, originating from sub-tropical regions, has spread into temperate climate zones in almost all continents. Potential factors in its success are temperature, light and nutrient levels. Grazing losses through zooplankton have been measured in the laboratory but are typically not regarded as a factor in (failed) invasion success. In some potentially suitable lakes, C. raciborskii has never been found, although it is present in water bodies close by. Therefore, we tested the invasive potential of three different isolates introduced into natural plankton communities using laboratory mesocosm experiments under three grazing levels: ambient zooplankton densities, removal of large species using 100 mu m mesh and a ca. doubling of large species. Three C. raciborskii isolates originating from the same geographic region (North-East Germany) were added separately to the four replicates of each treatment and kept in semi-continuous cultures for 21 days. Two isolates disappeared from the mesocosms and were also not viable in filtered lake water indicating that the lake water itself or the switch from culture medium to lake water led to the decay of the inoculated C. raciborskii. Only one out of the three isolates persisted in the plankton communities at a rather low level and only in the treatment without larger zooplankton. This result demonstrates that under potentially suitable environmental conditions, top-down control from zooplankton might hamper the establishment of C. raciborskii. Non-metric multidimensional scaling showed distinct variation in resident phytoplankton communities between the different grazing levels, thus differential grazing impact shaped the resident community in different ways allowing C. raciborskii only to invade under competitive (= low grazing pressure) conditions. Furthermore, even after invasion failure, the temporary presence of C. raciborskii influenced the phytoplankton community.
Due to increasing pressure on estuarine marshes from sea level rise and river training, there is a growing need to understand how species-environment relationships influence the zonation and growth of tidal marsh vegetation. In the present study, we investigated the distribution and stand characteristics of the two key brackish marsh species Bolboschoenus maritimus and Phragmites australis in the Elbe estuary together with several abiotic habitat factors. We then tested the effect of these habitat factors on plant growth and zonation with generalised linear models (GLMs). Our study provides detailed information on the importance of single habitat factors and their interactions for controlling the distribution patterns and stand characteristics of two key marsh species. Our results suggest that flow velocity is the main factor influencing species distribution and stand characteristics and together with soil-water salinity even affects the inundation tolerance of the two specie investigated here. Additionally, inundation height and duration as well as interspecific competition helped explain the distribution patterns and stand characteristics. By identifying the drivers of marsh zonation and stand characteristics and quantifying their effects, this study provides useful information for evaluating a future contribution of tidal marsh vegetation to ecosystem-based shore protection.
Much of the literature in the field of international relations is currently concerned with the changing patterns of authority in world politics. This is particularly evident in the policy domain of climate change, where a number of authors have observed a relocation of authority in global climate governance. These scholars claim that multilateral treaty making has lost much of its spark, and they emphasize the emergence of transnational governance arrangements, such as city networks, private certification schemes, and business self-regulation. However, the different types of interactions between the various transnational climate initiatives and the intergovernmental level have not been studied in much detail and only recently attracted growing scholarly interest. Therefore, the present article addresses this issue and focuses on the interplay between three different transnational climate governance arrangements and the international climate regime. The analysis in this article underscores that substate and nonstate actors have attained several authoritative functions in global climate policy making. Nevertheless, the three case studies also demonstrate that this development does not imply that we are witnessing a general shift of authority away from the intergovernmental level toward transnational actors. Instead, what can be observed in global climate governance is an ongoing reconfiguration of authority, which apparently reaffirms the centrality of the international climate regime. Thus, this article points to the need for a more nuanced perspective on the changing patterns of authority in global climate governance. In a nutshell, this study shows that the international climate regime is not the only location where the problem of climate change is addressed, while it highlights the persistent authority of state-based forms of regulation.
Narratives of Belonging
(2017)
Die Darstellungen genealogischer Netzwerke waren in der Antike Ausdruck der Weltsicht ihrer Erzähler, mit deren Hilfe Nähe und Distanz zwischen verschiedenen Gruppen und Völkern ausgedrückt und hergestellt werden konnte. Auch Paulus bedient sich genealogischer Argumente, um die Beziehung nicht-jüdischer Christus-Gläubiger zu Israel und ihrem Gott zu verdeutlichen. Es handelt sich um eine ethnozentrische Argumentation, deren Fokus aber gleichzeitig eindeutig theozentrisch ist.
Using a standard repeated measures model with arbitrary true score distribution and normal error variables, we present some fundamental closed-form results which explicitly indicate the conditions under which regression effects towards (RTM) and away from the mean are expected. Specifically, we show that for skewed and bimodal distributions many or even most cases will show a regression effect that is in expectation away from the mean, or that is not just towards but actually beyond the mean. We illustrate our results in quantitative detail with typical examples from experimental and biometric applications, which exhibit a clear regression away from the mean (‘egression from the mean’) signature. We aim not to repeal cautionary advice against potential RTM effects, but to present a balanced view of regression effects, based on a clear identification of the conditions governing the form that regression effects take in repeated measures designs.
The past two decades have witnessed widespread scholarly interest in the role of cities in climate policy-making. This research has considerably improved our understanding of the local level in the global response to climate change. The present article synthesizes the literature on local climate policies with respect to the 1.5 degrees C target. While most studies have focused on pioneering cities and networks, we contend that the broader impacts of local climate actions and their relationship to regional, national, and international policy frameworks have not been studied in enough detail. Against this backdrop, we introduce the concept of upscaling and contend that local climate initiatives must go hand in hand with higher-level policies and be better integrated into the multi-level governance system.
To purchase or not?
(2017)
Although ecologically and socially responsible consumption helps to reduce the harmful effects of resource use for both nature and society, all types of consumption (whether green or fair) deplete valuable resources. At the same time, to maintain household financial sustainability, spending should not exceed a household's financial resources. Thus, economically sustainable consumption is related to the consumer's decision to not buy products and the disposition to forgo specific purchases. Based on a means-end chain approach, this study investigates consumer cognitive decision-making structures related to six distinct options for economically (non-)sustainable consumption. Whereas saving motives, waste concerns, and avoidance motivations support economically sustainable decisions, economically non-sustainable decision-making is directly linked to attaining overall life goals. By clustering respondents based on the elicited means-end chains, the study discloses four consumer groups with distinctive motivational structures. The study also reveals several obstacles to promoting economic sustainability, indicates methods to overcome such obstacles, and suggests avenues for future research.
Anhand von Daten der Mannheimer Risikokinderstudie, die sich mit der langfristigen Entwicklung von Kindern mit unterschiedlichen Risikobelastungen beschäftigt, wird gezeigt, wie Schutzfaktoren aufseiten des Kindes und seines familiären Umfelds im Verlauf der Entwicklung wirksam werden und zur Entstehung von Resilienz beitragen können. Eine besondere Rolle kommt dabei positiven frühen Eltern-Kind-Beziehungen zu (sowohl Mutter- als auch Vater-Kind-Interaktionen). Daneben spielen auch Interaktionserfahrungen im Alter von zwei Jahren des Kindes eine bedeutsame Rolle; diese schützen Risikokinder davor, eine ungünstige Entwicklung zu nehmen und tragen dazu bei, dass sich Kinder, die in psychosozialen Hochrisikofamilien aufwachsen, trotz ungünstiger „Startbedingungen“ positiv entwickeln. Neben Merkmalen der sozialen Umwelt nehmen auch sprachliche, sozial-emotionale und internale Kompetenzen des Kindes im Entwicklungsverlauf eine wichtige Rolle ein. Diese Kompetenzen ermöglichen es Risikokindern auch unter widrigen Lebensumständen (psychosoziale Hochrisikofamilien, Aufwachsen in Armutsverhältnissen) erfolgreich zu bestehen. Darüber hinaus zeigt die Arbeit, dass Resilienz ein Persönlichkeitsmerkmal ist, das ab dem frühen Erwachsenenalter eine hohe Stabilität besitzt. Mit diesen Befunden verweist die Arbeit auf die große Bedeutung der Resilienz bei der Vorhersage der langfristigen Entwicklung von Risikokindern.
For an arbitrary euclidean field F we introduce a central extension (G(F), Phi) of SL(2, F) admitting a left-ordering and study its algebraic properties. The elements of G(F) are order preserving bijections of the convex hull of Q in F. If F = R then G(F) is isomorphic to the classical universal covering group of the Lie group SL(2, R). Among other results we show that G(F) is a perfect group which possesses a rank 1 cone of exceptional type. We also prove that its centre is an infinite cyclic group and investigate its normal subgroups.
DPP4 inhibition prevents AKI
(2017)
To investigate and compare the occurrence of inflammatory processes in the sites of disc degeneration in the lumbar and cervical spine by a gene array and subsequent qPCR and to investigate the mechanistic involvement of transient receptor potential channels TRPC6 and TRPV4. The gene expression of inflammatory cytokines and TRP channels was measured in human disc samples obtained from patients undergoing discectomy at the cervical (n = 24) or lumbar (n = 27) spine for degenerative disc disease (DDD) and disc herniation (DH) and analyzed for differences with regard to spinal level, IVD degeneration grade, Modic grade, age, sex, disc region and surgical extent. Aside from genes with known implication in DDD and DH, four previously unreported genes from the interferon and TRP families (IFNA1, IFNA8, IFNB1, TRPC6) could be detected. A correlation between gene expression and age (IL-15) and IVD degeneration grade (IFNA1, IL-6, IL-15, TRPC6), but not Modic grade, was identified. Significant differences were detected between cervical and lumbar discs (IL-15), nucleus and annulus (IL-6, TNF-alpha, TRPC6), single-level and multi-level surgery (IL-6, IL-8) as well as DDD and DH (IL-8), while sex had no effect. Multiple gene-gene pair correlations, either between different cytokines or between cytokines and TRP channels, exist in the disc. This study supports the relevance of IL-6 and IL-8 in disc diseases, but furthermore points toward a possible pathological role of IL-15 and type I interferons, as well as a mechanistic role of TRPC6. With limited differences in the inflammatory profile of cervical and lumbar discs, novel anti-inflammatory or TRP-modulatory strategies for the treatment of disc pathologies may be applicable independent of the spinal region.
Galaxies are surrounded by sizeable gas reservoirs which host a significant amount of metals: the circum-galactic medium (CGM). The CGM acts as a mediator between the galaxy and the extragalactic medium. However, our understanding of how galaxy mergers, a major evolutionary transformation, impact the CGM remains deficient. We present a theoretical study of the effect of galaxy mergers on the CGM. We use hydrodynamical cosmological zoom-in simulations of a major merger selected from the Illustris project such that the z = 0 descendant has a halo mass and stellar mass comparable to the Milky Way. To study the CGM we then re-simulated this system at a 40 times better mass resolution, and included detailed post-processing ionization modelling. Our work demonstrates the effect the merger has on the characteristic size of the CGM, its metallicity, and the predicted covering fraction of various commonly observed gas-phase species, such as H I, C IV, and O VI. We show that merger-induced outflows can increase the CGM metallicity by 0.2-0.3 dex within 0.5 Gyr post-merger. These effects last up to 6 Gyr post-merger. While the merger increases the total metal covering fractions by factors of 2-3, the covering fractions of commonly observed UV ions decrease due to the hard ionizing radiation from the active galactic nucleus, which we model explicitly. Our study of the single simulated major merger presented in this work demonstrates the significant impact that a galaxy interaction can have on the size, metallicity, and observed column densities of the CGM.