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Questions Has plant species richness in semi-natural grasslands changed over recent decades? Do the temporal trends of habitat specialists differ from those of habitat generalists? Has there been a homogenization of the grassland vegetation? Location Different regions in Germany and the UK. Methods We conducted a formal meta-analysis of re-survey vegetation studies of semi-natural grasslands. In total, 23 data sets were compiled, spanning up to 75 years between the surveys, including 13 data sets from wet grasslands, six from dry grasslands and four from other grassland types. Edaphic conditions were assessed using mean Ellenberg indicator values for soil moisture, nitrogen and pH. Changes in species richness and environmental variables were evaluated using response ratios. Results In most wet grasslands, total species richness declined over time, while habitat specialists almost completely vanished. The number of species losses increased with increasing time between the surveys and were associated with a strong decrease in soil moisture and higher soil nutrient contents. Wet grasslands in nature reserves showed no such changes or even opposite trends. In dry grasslands and other grassland types, total species richness did not consistently change, but the number or proportions of habitat specialists declined. There were also considerable changes in species composition, especially in wet grasslands that often have been converted into intensively managed, highly productive meadows or pastures. We did not find a general homogenization of the vegetation in any of the grassland types. Conclusions The results document the widespread deterioration of semi-natural grasslands, especially of those types that can easily be transformed to high production grasslands. The main causes for the loss of grassland specialists are changed management in combination with increased fertilization and nitrogen deposition. Dry grasslands are most resistant to change, but also show a long-term trend towards an increase in more mesotrophic species.
J. Dewey and H. Plessner both and independently of one another treated the central question of what new task philosophy must set itself if the assumption is correct that the life-form of mind, i.e., the mental life-form of humans, arose in nature and must also sustain itself in the future within nature. If nature has to reconceived so as to make the irreducible qualities of life and mind truly possible, then it can no longer be restricted to the role of physical material. Conversely humans cannot no longer take on the role of God outside and independent of nature. Instead these philosophers distinguish between three plateaus (Dewey) or stages (Plessner), between physical (inorganic) nature, psycho-physical (living) nature and the nature that is mental life. This distinction is drawn such that a connection between the plateaus is truly possible. The third level, that of the mental form of life, answers mentally within conduct to the break with the first two levels. Hence it depends in the future as well on the continuously renewed difference (between the precarious and the stable for Dewey, between immediacy and mediation for Plessner) in our experience of nature. Within this difference nature as a whole remains an open unknown, which is why we can credit Dewey with a philosophy of diversified and negative holism, Plessner with a differential philosophy of the negativity of the absolute.
This study is concerned with repair practices that a teacher and students employ to restore intersubjectivity when faced with interactional problems in a Content and Language Integrated Learning (CLIL) classroom. Adopting a conversation analytic (CA) approach, it examines the interactional treatment of students’ verbal and embodied trouble displays in a video-recorded, teacher-fronted geography lesson held in English at a German high school. At the same time, it explores to what extent the repair practices employed are fitted to this specific interactional context. The analysis shows that students’ verbal trouble displays often result in extensive repair sequences, whereas students’ embodied trouble displays are usually met with teacher self-repair in the transition space. In this way, the latter are resolved much earlier and more quickly. The study further reveals practices like reformulation and translation to be especially useful for repairing interactional problems in classrooms in which a foreign language is used as the medium of instruction. The findings may be of interest for prospective as well as practicing teachers in that they provide relevant insights into how interactional trouble can be successfully managed in (CLIL) classroom interaction.
Persulfide groups participate in a wide array of biochemical pathways and are chemically very versatile. The TusA protein has been identified as a central element supplying and transferring sulfur as persulfide to a number of important biosynthetic pathways, like molybdenum cofactor biosynthesis or thiomodifications in nucleosides of tRNAs. In recent years, it has furthermore become obvious that this protein is indispensable for the oxidation of sulfur compounds in the cytoplasm. Phylogenetic analyses revealed that different TusA protein variants exists in certain organisms, that have evolved to pursue specific roles in cellular pathways. The specific TusA-like proteins thereby cannot replace each other in their specific roles and are rather specific to one sulfur transfer pathway or shared between two pathways. While certain bacteria like Escherichia coli contain several copies of TusA-like proteins, in other bacteria like Allochromatium vinosum a single copy of TusA is present with an essential role for this organism. Here, we give an overview on the multiple roles of the various TusA-like proteins in sulfur transfer pathways in different organisms to shed light on the remaining mysteries of this versatile protein.
It is assumed that additionally to the family background and child characteris-tics, the children’s learning environments are crucial for the acquisition of early competencies. This study aimed to compare the eff ects of home and institutional learning environment on young children’s vocabulary and to test necessary con-ditions for a potential compensatory eff ect of the institutional learning environ-ment. Using longitudinal data from N = 557 preschool children (German National Educational Panel Study), we analysed to what extent family background and children’s characteristics predicted home and institutional learning environments and to what extent these learning environments predicted vocabulary in pre-school and primary school. In order to test if both learning environments pre-dict vocabulary separately, we used almost identical indicators to operationalize them. The effects were estimated within a structural equation model. The study revealed that both, home and institutional learning environment, had small and separate eff ects on children’s vocabulary. The home learning environment was more closely related to the family background, while the institutional learning en-vironment was more closely related to the children’s characteristics. This evokes new possibilities to discuss compensatory effect.
Estimating parameters from multiple time series of population dynamics using bayesian inference
(2019)
Empirical time series of interacting entities, e.g., species abundances, are highly useful to study ecological mechanisms. Mathematical models are valuable tools to further elucidate those mechanisms and underlying processes. However, obtaining an agreement between model predictions and experimental observations remains a demanding task. As models always abstract from reality one parameter often summarizes several properties. Parameter measurements are performed in additional experiments independent of the ones delivering the time series. Transferring these parameter values to different settings may result in incorrect parametrizations. On top of that, the properties of organisms and thus the respective parameter values may vary considerably. These issues limit the use of a priori model parametrizations. In this study, we present a method suited for a direct estimation of model parameters and their variability from experimental time series data. We combine numerical simulations of a continuous-time dynamical population model with Bayesian inference, using a hierarchical framework that allows for variability of individual parameters. The method is applied to a comprehensive set of time series from a laboratory predator-prey system that features both steady states and cyclic population dynamics. Our model predictions are able to reproduce both steady states and cyclic dynamics of the data. Additionally to the direct estimates of the parameter values, the Bayesian approach also provides their uncertainties. We found that fitting cyclic population dynamics, which contain more information on the process rates than steady states, yields more precise parameter estimates. We detected significant variability among parameters of different time series and identified the variation in the maximum growth rate of the prey as a source for the transition from steady states to cyclic dynamics. By lending more flexibility to the model, our approach facilitates parametrizations and shows more easily which patterns in time series can be explained also by simple models. Applying Bayesian inference and dynamical population models in conjunction may help to quantify the profound variability in organismal properties in nature.
We study the requirement of the jet power in the conventional p-gamma models (photopion production and Bethe-Heitler pair production) for TeV BL Lac objects. We select a sample of TeV BL Lac objects whose spectral energy distributions are difficult to explain by the one-zone leptonic model. Based on the relation between the p-gamma interaction efficiency and the opacity of gamma gamma absorption, we find that the detection of TeV emission poses upper limits on the p-gamma interaction efficiencies in these sources and hence minimum jet powers can be derived accordingly. We find that the obtained minimum jet powers exceed the Eddington luminosity of the supermassive black holes (SMBHs). Implications for the accretion mode of the SMBHs in these BL Lac objects and the origin of their TeV emissions are discussed.
Trotz unzähliger Forschungsbeiträge zur Literaturnobelpreisträgerin Elfriede Jelinek und dem „Verweigerungskünstler“ Thomas Bernhard wurde den Verbindungslinien beider Autoren noch nie vergleichend nachgegangen. Der Band erschließt zum 30. Todestag Bernhards (u. 15 Jahre Nobelpreis für Jelinek) anschaulich ein breit gefächertes Spektrum an Themen, Perspektiven und Werken beider Schriftsteller im Vergleich. Mit einem Essay von Elfriede Jelinek.
Various studies have implied the existence of a gaseous halo around the Galaxy extending out to similar to 100 kpc. Galactic cosmic rays (CRs) that propagate to the halo, either by diffusion or by convection with the possibly existing large-scale Galactic wind, can interact with the gas therein and produce gamma-rays via proton-proton collision. We calculate the CR distribution in the halo and the gamma-ray flux, and explore the dependence of the result on model parameters such as diffusion coefficient, CR luminosity, and CR spectral index. We find that the current measurement of isotropic gamma-ray background (IGRB) at less than or similar to TeV with the Fermi Large Area Telescope already approaches a level that can provide interesting constraints on the properties of Galactic CR (e.g., with CR luminosity L-CR <= 1041 erg s(-1)). We also discuss the possibilities of the Fermi bubble and IceCube neutrinos originating from the proton-proton collision between CRs and gas in the halo, as well as the implication of our results for the baryon budget of the hot circumgalactic medium of our Galaxy. Given that the isotropic gamma-ray background is likely to be dominated by unresolved extragalactic sources, future telescopes may extract more individual sources from the IGRB, and hence put even more stringent restrictions on the relevant quantities (such as Galactic CR luminosity and baryon budget in the halo) in the presence of a turbulent halo that we consider.
Stuck in the past?
(2019)
After the Civil War the Spanish army functioned as a guardian of domestic order, but suffered from antiquated material and little financial means. These factors have been described as fundamental reasons for the army’s low potential wartime capability. This article draws on British and German sources to demonstrate how Spanish military culture prevented an augmented effectiveness and organisational change. Claiming that the army merely lacked funding and modern equipment, falls considerably short in grasping the complexities of military effectiveness and organisational cultures, and might prove fatal for current attempts to develop foreign armed forces in conflict or post-conflict zones.
Mixed methods approaches have become increasingly relevant in social sciences research over the last few decades. Nevertheless, we show that these approaches have rarely been explicitly applied in higher education research. This is somewhat surprising because mixed methods and empirical research into higher education seem to be a perfect match for several reasons: (1) the role of the researcher, which is associated with strong intersections between the research subject and the research object; (2) the research process, which relies on concepts and theories that are borrowed from other research fields; and (3) the research object, which exhibits unclear techniques in teaching and learning, making it difficult to grasp causalities between input and results. Mixed methods approaches provide a suitable methodology to research such topics. Beyond this, potential future developments underlining the particular relevance of mixed methods approaches in higher education are discussed.
The size structure of autotroph communities - the relative abundance of small vs. large individuals - shapes the functioning of ecosystems. Whether common mechanisms underpin the size structure of unicellular and multicellular autotrophs is, however, unknown. Using a global data compilation, we show that individual body masses in tree and phytoplankton communities follow power-law distributions and that the average exponents of these individual size distributions (ISD) differ. Phytoplankton communities are characterized by an average ISD exponent consistent with three-quarter-power scaling of metabolism with body mass and equivalence in energy use among mass classes. Tree communities deviate from this pattern in a manner consistent with equivalence in energy use among diameter size classes. Our findings suggest that whilst universal metabolic constraints ultimately underlie the emergent size structure of autotroph communities, divergent aspects of body size (volumetric vs. linear dimensions) shape the ecological outcome of metabolic scaling in forest vs. pelagic ecosystems.
Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine - typically rapidly - and valleys typically should widen gradually. To match the empirical square-root width-discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution.
A central claim by Hoerl & McCormack is that the temporal reasoning system is uniquely human. But why exactly? This commentary evaluates two possible options to justify the thesis that temporal reasoning is uniquely human, one based on considerations regarding agency and the other based on language. The commentary raises problems for both of these options.
Background: The polymorphism in FTO gene (rs9939609) is known to be associated with higher BMI and body fat mass content. However, environmental factors can modify this effect. The purpose of the present study was to investigate an association between sport specialization and the rs9939609 SNP in FTO gene in the cohort of professional and amateur young athletes. Methods: A total number of 250 young individuals 8-18 years old living in Moscow or Moscow district participated in the study. Individuals were divided into 3 groups in accordance with their physical activity level: control group (n = 49), amateurs (n = 67) and professionals (n = 137). Amateur and professional athletes were subdivided into groups according to their sport specialization. Quantile regression was used as a regression model, where the dependent (outcome) variable was BMI, along with percentage of body fat mass, and the independent variables (predictors) were the rs9939609 SNP in FTO gene, physical activity (active versus inactive), sport specialization (aerobic, intermittent sports and martial arts), nationality, level of sport experience (in years), gender and percentage of free fat mass content. Results: The regression analysis revealed that physical activity and sport specialization had greater impact compared to FTO allele in the group of physically active individuals. Physical activity, in particular aerobic, had negative associations with body fat mass and BMI. The rs9939609 SNP in FTO gene is associated with physical activity and aerobic activity. The magnitude of association becomes significantly larger at the upper quantiles of the body fat mass distribution. Conclusion: Physical activity and sport specialization explained more variance in body composition of physically active young individuals compared to the FTO polymorphism. Effect of interaction of physical activity, in particular aerobic, with the FTO polymorphism on body composition of young athletes was found.