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A series of symmetrical, thermo-responsive triblock copolymers was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization, and studied in aqueous solution with respect to their ability to form hydrogels. Triblock copolymers were composed of two identical, permanently hydrophobic outer blocks, made of low molar mass polystyrene, and of a hydrophilic inner block of variable length, consisting of poly(methoxy diethylene glycol acrylate) PMDEGA. The polymers exhibited a LCST-type phase transition in the range of 20-40 degrees C, which markedly depended on molar mass and concentration. Accordingly, the triblock copolymers behaved as amphiphiles at low temperatures, but became water-insoluble at high temperatures. The temperature dependent self-assembly of the amphiphilic block copolymers in aqueous solution was studied by turbidimetry and rheology at concentrations up to 30 wt %, to elucidate the impact of the inner thermoresponsive block on the gel properties. Additionally, small-angle X-ray scattering (SAXS) was performed to access the structural changes in the gel with temperature. For all polymers a gel phase was obtained at low temperatures, which underwent a gel-sol transition at intermediate temperatures, well below the cloud point where phase separation occurred. With increasing length of the PMDEGA inner block, the gel-sol transition shifts to markedly lower concentrations, as well as to higher transition temperatures. For the longest PMDEGA block studied (DPn about 450), gels had already formed at 3.5 wt % at low temperatures. The gel-sol transition of the hydrogels and the LCST-type phase transition of the hydrophilic inner block were found to be independent of each other.
Thermomechanical model reconciles contradictory geophysical observations at the Dead Sea Basin
(2012)
The Dead Sea Transform (DST) comprises a boundary between the African and Arabian plates. During the last 15-20 m.y. more than 100 km of left lateral transform displacement has been accumulated on the DST and about 10 km thick Dead Sea Basin (DSB) was formed in the central part of the DST. Widespread igneous activity since some 20 Ma ago and especially in the last 5 m.y., thin (60-80 km) lithosphere constrained by seismic data and absence of seismicity below the Moho, seem to be quite natural for this tectonically active plate boundary. However, surface heat flow values of less than 50-60 mW/m(2) and deep seismicity in the lower crust (deeper than 20 km) reported for this region are apparently inconsistent with the tectonic settings specific for an active continental plate boundary and with the crustal structure of the DSB. To address these inconsistencies which comprise what we call the "DST heat-flow paradox," we have developed a numerical model that assumes an erosion of initially thick and cold lithosphere just before or during the active faulting at the DST. The optimal initial conditions for the model are defined using transient thermal analysis. From the results of our numerical experiments we conclude that the entire set of observations for the DSB can be explained within the classical pull-apart model assuming that the lithosphere has been thermally eroded at about 20 Ma and the uppermost mantle in the region have relatively weak rheology consistent with experimental data for wet olivine or pyroxenite.
Current climate warming is affecting arctic regions at a faster rate than the rest of the world. This has profound effects on permafrost that underlies most of the arctic land area. Permafrost thawing can lead to the liberation of considerable amounts of greenhouse gases as well as to significant changes in the geomorphology, hydrology, and ecology of the corresponding landscapes, which may in turn act as a positive feedback to the climate system. Vast areas of the east Siberian lowlands, which are underlain by permafrost of the Yedoma-type Ice Complex, are particularly sensitive to climate warming because of the high ice content of these permafrost deposits. Thermokarst and thermal erosion are two major types of permafrost degradation in periglacial landscapes. The associated landforms are prominent indicators of climate-induced environmental variations on the regional scale. Thermokarst lakes and basins (alasses) as well as thermo-erosional valleys are widely distributed in the coastal lowlands adjacent to the Laptev Sea. This thesis investigates the spatial distribution and morphometric properties of these degradational features to reconstruct their evolutionary conditions during the Holocene and to deduce information on the potential impact of future permafrost degradation under the projected climate warming. The methodological approach is a combination of remote sensing, geoinformation, and field investigations, which integrates analyses on local to regional spatial scales. Thermokarst and thermal erosion have affected the study region to a great extent. In the Ice Complex area of the Lena River Delta, thermokarst basins cover a much larger area than do present thermokarst lakes on Yedoma uplands (20.0 and 2.2 %, respectively), which indicates that the conditions for large-area thermokarst development were more suitable in the past. This is supported by the reconstruction of the development of an individual alas in the Lena River Delta, which reveals a prolonged phase of high thermokarst activity since the Pleistocene/Holocene transition that created a large and deep basin. After the drainage of the primary thermokarst lake during the mid-Holocene, permafrost aggradation and degradation have occurred in parallel and in shorter alternating stages within the alas, resulting in a complex thermokarst landscape. Though more dynamic than during the first phase, late Holocene thermokarst activity in the alas was not capable of degrading large portions of Pleistocene Ice Complex deposits and substantially altering the Yedoma relief. Further thermokarst development in existing alasses is restricted to thin layers of Holocene ice-rich alas sediments, because the Ice Complex deposits underneath the large primary thermokarst lakes have thawed completely and the underlying deposits are ice-poor fluvial sands. Thermokarst processes on undisturbed Yedoma uplands have the highest impact on the alteration of Ice Complex deposits, but will be limited to smaller areal extents in the future because of the reduced availability of large undisturbed upland surfaces with poor drainage. On Kurungnakh Island in the central Lena River Delta, the area of Yedoma uplands available for future thermokarst development amounts to only 33.7 %. The increasing proximity of newly developing thermokarst lakes on Yedoma uplands to existing degradational features and other topographic lows decreases the possibility for thermokarst lakes to reach large sizes before drainage occurs. Drainage of thermokarst lakes due to thermal erosion is common in the study region, but thermo-erosional valleys also provide water to thermokarst lakes and alasses. Besides these direct hydrological interactions between thermokarst and thermal erosion on the local scale, an interdependence between both processes exists on the regional scale. A regional analysis of extensive networks of thermo-erosional valleys in three lowland regions of the Laptev Sea with a total study area of 5,800 km² found that these features are more common in areas with higher slopes and relief gradients, whereas thermokarst development is more pronounced in flat lowlands with lower relief gradients. The combined results of this thesis highlight the need for comprehensive analyses of both, thermokarst and thermal erosion, in order to assess past and future impacts and feedbacks of the degradation of ice-rich permafrost on hydrology and climate of a certain region.
Thermodynamics, kinetics and rheology of surfactant adsorption layers at water/oil interfaces
(2012)
The timing of Tibetan plateau development remains elusive, despite its importance for evaluating models of continental lithosphere deformation and associated changes in surface elevation and climate. We present new thermochronologic data [biotite and K-feldspar Ar-40/Ar-39, apatite fission track, and apatite (U-Th)/He] from the central Tibetan plateau (Lhasa and Qiangtang terranes). The data indicate that over large regions, rocks underwent rapid to moderate cooling and exhumation during Cretaceous to Eocene time. This was coeval with >50% upper crustal shortening, suggesting substantial crustal thickening and surface elevation gain. Thermal modeling of combined thermochronometers requires exhumation of most samples to depths of <3 km between 85 and 45 Ma, followed by a decrease in erosional exhumation rate to low values of <0.05 mm/yr. The thermochronological results, when interpreted in the context of the deformation and paleoaltimetric history, are best explained by a scenario of plateau growth that began locally in central Tibet during the Late Cretaceous and expanded to encompass most of central Tibet by 45 Ma.
In this work, we show how Gibbs or thermal states appear dynamically in closed quantum many-body systems, building on the program of dynamical typicality. We introduce a novel perturbation theorem for physically relevant weak system-bath couplings that is applicable even in the thermodynamic limit. We identify conditions under which thermalization happens and discuss the underlying physics. Based on these results, we also present a fully general quantum algorithm for preparing Gibbs states on a quantum computer with a certified runtime and error bound. This complements quantum Metropolis algorithms, which are expected to be efficient but have no known runtime estimates and only work for local Hamiltonians.
Theory of mRNA degradation
(2012)
One of the central themes of biology is to understand how individual cells achieve a high fidelity in gene expression. Each cell needs to ensure accurate protein levels for its proper functioning and its capability to proliferate. Therefore, complex regulatory mechanisms have evolved in order to render the expression of each gene dependent on the expression level of (all) other genes. Regulation can occur at different stages within the framework of the central dogma of molecular biology. One very effective and relatively direct mechanism concerns the regulation of the stability of mRNAs. All organisms have evolved diverse and powerful mechanisms to achieve this. In order to better comprehend the regulation in living cells, biochemists have studied specific degradation mechanisms in detail. In addition to that, modern high-throughput techniques allow to obtain quantitative data on a global scale by parallel analysis of the decay patterns of many different mRNAs from different genes. In previous studies, the interpretation of these mRNA decay experiments relied on a simple theoretical description based on an exponential decay. However, this does not account for the complexity of the responsible mechanisms and, as a consequence, the exponential decay is often not in agreement with the experimental decay patterns. We have developed an improved and more general theory of mRNA degradation which provides a general framework of mRNA expression and allows describing specific degradation mechanisms. We have made an attempt to provide detailed models for the regulation in different organisms. In the yeast S. cerevisiae, different degradation pathways are known to compete and furthermore most of them rely on the biochemical modification of mRNA molecules. In bacteria such as E. coli, degradation proceeds primarily endonucleolytically, i.e. it is governed by the initial cleavage within the coding region. In addition, it is often coupled to the level of maturity and the size of the polysome of an mRNA. Both for S. cerevisiae and E. coli, our descriptions lead to a considerable improvement of the interpretation of experimental data. The general outcome is that the degradation of mRNA must be described by an age-dependent degradation rate, which can be interpreted as a consequence of molecular aging of mRNAs. Within our theory, we find adequate ways to address this much debated topic from a theoretical perspective. The improvements of the understanding of mRNA degradation can be readily applied to further comprehend the mRNA expression under different internal or environmental conditions such as after the induction of transcription or stress application. Also, the role of mRNA decay can be assessed in the context of translation and protein synthesis. The ultimate goal in understanding gene regulation mediated by mRNA stability will be to identify the relevance and biological function of different mechanisms. Once more quantitative data will become available, our description allows to elaborate the role of each mechanism by devising a suitable model.
The zoom lens of attention simulating shuffled versus normal text reading using the SWIFT model
(2012)
Assumptions on the allocation of attention during reading are crucial for theoretical models of eye guidance. The zoom lens model of attention postulates that attentional deployment can vary from a sharp focus to a broad window. The model is closely related to the foveal load hypothesis, i.e., the assumption that the perceptual span is modulated by the difficulty of the fixated word. However, these important theoretical concepts for cognitive research have not been tested quantitatively in eye movement models. Here we show that the zoom lens model, implemented in the SWIFT model of saccade generation, captures many important patterns of eye movements. We compared the model's performance to experimental data from normal and shuffled text reading. Our results demonstrate that the zoom lens of attention might be an important concept for eye movement control in reading.
Over the last three decades, the German political economy can be characterized by both institutional continuity and change. Understanding the dynamics of institutional change therefore requires an examination of the interplay of changes in formal institutional rules and how organizations respond to these changes by strategic attempts to promote or hinder further change in institutions. The macro-level political story of institutional change shows a number of paradoxes resulting in unexpected and often incomplete forms of market liberalization shaped by continued support for some core features of Germany's social market economy. The resulting erosion of Germany's co-ordinated model of economic organization through networks and business associations has gone hand-in-hand with the attempts to preserve these institutions for core workers and sectors of the economy in the face of changing environments. The result is a more varied institutional landscape characterized by international diffusion of liberal policies and the politics of their variable re-embedding within a long-term path of institutional continuity.
Using the eye-movement monitoring technique in two reading comprehension experiments, this study investigated the timing of constraints on wh-dependencies (so-called island constraints) in first- and second-language (L1 and L2) sentence processing. The results show that both L1 and L2 speakers of English are sensitive to extraction islands during processing, suggesting that memory storage limitations affect L1 and L2 comprehenders in essentially the same way. Furthermore, these results show that the timing of island effects in L1 compared to L2 sentence comprehension is affected differently by the type of cue (semantic fit versus filled gaps) signaling whether dependency formation is possible at a potential gap site. Even though L1 English speakers showed immediate sensitivity to filled gaps but not to lack of semantic fit, proficient German-speaking learners of English as a L2 showed the opposite sensitivity pattern. This indicates that initial wh-dependency formation in L2 processing is based on semantic feature matching rather than being structurally mediated as in L1 comprehension.
Using the eye-movement monitoring technique in two reading comprehension experiments, this study investigated the timing of constraints on wh-dependencies (so-called island constraints) in first- and second-language (L1 and L2) sentence processing. The results show that both L1 and L2 speakers of English are sensitive to extraction islands during processing, suggesting that memory storage limitations affect L1 and L2 comprehenders in essentially the same way. Furthermore, these results show that the timing of island effects in L1 compared to L2 sentence comprehension is affected differently by the type of cue (semantic fit versus filled gaps) signaling whether dependency formation is possible at a potential gap site. Even though L1 English speakers showed immediate sensitivity to filled gaps but not to lack of semantic fit, proficient German-speaking learners of English as a L2 showed the opposite sensitivity pattern. This indicates that initial wh-dependency formation in L2 processing is based on semantic feature matching rather than being structurally mediated as in L1 comprehension.
This article examines Pierre Nora’s concept of memory using the examples of York and Winchester to demonstrate the individuality of local approaches to the memory of medieval Anglo-Jewries. Overall, this paper will highlight how memory can be rescued from a period of prolonged silence and reintegrated back into a wider historical narrative. Conversely it will also examine how in stark contrast to this new attitude of remembering the silence surrounding Jewish memory continues to exist elsewhere. Finally this paper will ask why this silence remains, and question whether Nora’s theory that memory is constantly evolving is applicable to the experiences of Jewish memory in York and Winchester.
SXP 1062 is an exceptional case of a young neutron star in a wind-fed high-mass X-ray binary associated with a supernova remnant. A unique combination of measured spin period, its derivative, luminosity and young age makes this source a key probe for the physics of accretion and neutron star evolution. Theoretical models proposed to explain the properties of SXP 1062 shall be tested with new data.
As a part of the DEad Sea Integrated REsearch (DESIRE) project a near-vertical incidence reflection (NVR) experiment with a profile length of 122 km was completed in spring 2006. The profile crossed the southern Dead Sea basin (DSB), a pull-apart basin due to the strike-slip motion along the Dead Sea Transform (DST). The DST with a total displacement of 107 km since about 18 Ma is part of a left-lateral fault system which connects the spreading centre in the Red Sea with the Taurus collision zone in Turkey over a distance of about 1100 km. The seismic experiment comprises 972 source locations and 1045 receiver locations. Each source was recorded by similar to 180 active receivers and a field data set with 175 000 traces was created. From this data set, 124 444 P-wave first-break traveltimes have been picked. With these traveltimes a tomographic inversion was carried out, resulting in a 2-D P-wave velocity model with a rms error of 20.9 ms. This model is dominated by a low-velocity region associated with the DSB. Within the DSB, the model shows clearly the position of the Lisan salt diapir, identified by a high-velocity zone. A further feature is an unexpected laterally low-velocity zone with P-velocities of 3 km s1 embedded in regions with 4 km s1 in the shallow part on the west side of the DSB. Another observation is an anticlinal structure west of the DSB interpretated to the related Syrian arc fold belt.
The paper presents the sediment budget of the Isabena basin, a highly dynamic 445-km(2) catchment located in the Central Pyrenees that is patched by highly erodible areas (i.e., badlands). The budget for the period 2007-2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads. Data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet. Mean annual sediment load was 235,000 t y(-1). Specific sediment yield reached 2000 t km(-2) y(-1), a value that indicates very high sedimentary activity, especially in the case of Villacarli and Lascuarre subcatchments, were most badlands are located. The specific sediment yield obtained for the entire Isabena is 527 t km(-2) y(-1), a high value for such a mesoscale basin. Results show that a small part of the area (i.e., 1%) controls most of the catchment's gross sediment contribution. Sediment delivery ratio (ratio between sediment input from primary sources and basin export) has been estimated at around 90%, while in-channel storage represents the 5% of the annual load on average. The high connectivity between sediment sources (i.e., badlands) and transfer paths (i.e., streamcourses) exacerbates the influence of the local sediment production on the catchment's sediment yield, a quite unusual fact for a basin of this scale.
The meaning of linguistic connectives has often been characterized in terms of their position in a bipartite (semantic, pragmatic) or a tripartite (content, epistemic, speech act) structure of domains, depending on what kinds of entities are being connected (largely: propositions or speech acts). This paper argues that a more fine-grained analysis can be achieved by directing some more attention to the characterization of the entities being related. We propose an inventory of categories of illocutionary status for labelling the spans that are being connected. On this basis, the distinction between the content and the epistemic domain, in particular, can be made more explicit. Focusing on the group of causal connectives in German, we conducted a corpus annotation study from which we derived distinct pragmatic 'usage profiles' of the most frequent causal connectives. Finally, we offer some suggestions on the role of illocutions in relation-based accounts of discourse structure.
The role of ergodicity in anomalous stochastic processes - analysis of single-particle trajectories
(2012)
Single-particle experiments produce time series x(t) of individual particle trajectories, frequently revealing anomalous diffusion behaviour. Typically, individual x(t) are evaluated in terms of time-averaged quantities instead of ensemble averages. Here we discuss the behaviour of the time-averaged mean squared displacement of different stochastic processes giving rise to anomalous diffusion. In particular, we pay attention to the ergodic properties of these processes, i.e. the (non)equivalence of time and ensemble averages.
The role of alcohol and victim sexual interest in spanish students' perceptions of sexual assault
(2012)
Two studies investigated the effects of information related to rape myths on Spanish college students' perceptions of sexual assault. In Study 1, 92 participants read a vignette about a nonconsensual sexual encounter and rated whether it was a sexual assault and how much the woman was to blame. In the scenario, the man either used physical force or offered alcohol to the woman to overcome her resistance. Rape myth acceptance (RMA) was measured as an individual difference variable. Participants were more convinced that the incident was a sexual assault and blamed the woman less when the man had used force rather than offering her alcohol. In Study 2, 164 college students read a scenario in which the woman rejected a man's sexual advances after having either accepted or turned down his offer of alcohol. In addition, the woman was either portrayed as being sexually attracted to him or there was no mention of her sexual interest. Participants' RMA was again included. High RMA participants blamed the victim more than low RMA participants and were less certain that the incident was a sexual assault, especially when the victim had accepted alcohol and was described as being sexually attracted to the man. The findings are discussed in terms of their implications for the prevention and legal prosecution of sexual assault.
We present a toy-model for an ensemble of adhering mesoscopic constituents in order to estimate the effect of the granular temperature on the sizes of embedded aggregates. The major goal is to illustrate the relation between the mean aggregate size and the granular temperature in dense planetary rings. For sake of simplicity we describe the collective behavior of the ensemble by means of equilibrium statistical mechanics, motivated by the stationary temperature established by the balance between a Kepler-shear driven viscous heating and inelastic cooling in these cosmic granular disks. The ensemble consists of N' equal constituents which can form cluster(s) or move like a gas-or both phases may coexist-depending on the (granular) temperature of the system. We assume the binding energy levels of a cluster E-c = -N-c gamma a to be determined by a certain contact number N-c, given by the configuration of N constituents of the aggregate (energy per contact: -gamma a). By applying canonical and grand-canonical ensembles, we show that the granular temperature T of a gas of constituents (their mean kinetic energy) controls the size distribution of the aggregates. They are the smaller the higher the granular temperature T is. A mere gas of single constituents is sustained for T >> gamma a. In the case of large clusters (low temperatures T << gamma a) the size distribution becomes a Poissonian.
The response of forest plant regeneration to temperature variation along a latitudinal gradient
(2012)
The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming.
Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments.
Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted.
Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.
This paper introduces and analyses a general statistical model, termed the RAndom RElaxations (RARE) model, of random relaxation processes in disordered systems. The model considers excitations that are randomly scattered around a reaction center in a general embedding space. The model's input quantities are the spatial scattering statistics of the excitations around the reaction center, and the chemical reaction rates between the excitations and the reaction center as a function of their mutual distance. The framework of the RARE model is versatile and a detailed stochastic analysis of the random relaxation processes is established. Analytic results regarding the duration and the range of the random relaxation processes, as well as the model's thermodynamic limit, are obtained in closed form. In particular, the case of power-law inputs, which turn out to yield stretched exponential relaxation patterns and asymptotically Paretian relaxation ranges, is addressed in detail.
The Quintuplet, one of three massive stellar clusters in the Galactic center (GC), is located about 30 pc in projection from Sagittarius A*. We aim at the construction of the Hertzsprung-Russell diagram (HRD) of the cluster to study its evolution and to constrain its star-formation history. For this purpose we use the most complete spectral catalog of the Quintuplet stars. Based on the K-band spectra we determine stellar temperatures and luminosities for all stars in the catalog under the assumption of a uniform reddening towards the cluster. We find two groups in the resulting HRD: early-type OB stars and late-type KM stars, well separated from each other. By comparison with Geneva stellar evolution models we derive initial masses exceeding 8 M-circle dot for the OB stars. In the HRD these stars are located along an isochrone corresponding to an age of about 4 Myr. This confirms previous considerations, where a similar age estimate was based on the presence of evolved Wolf-Rayet stars in the cluster. We derive number ratios for the various spectral subtype groups (e.g. N-WR/N-O, N-WC/N-WN) and compare them with predictions of population synthesis models. We find that an instantaneous burst of star formation at about 3.3 to 3.6 Myr ago is the most likely scenario to form the Quintuplet cluster. Furthermore, we apply a mass-luminosity relation to construct the initial mass function (IMF) of the cluster. We find indications for a slightly top-heavy IMF. The late-type stars in the LHO catalog are red giant branch (RGB) stars or red supergiants (RSGs) according to their spectral signatures. Under the assumption that they are located at about the distance of the Galactic center we can derive their luminosities. The comparison with stellar evolution models reveals that the initial masses of these stars are lower than 15 M-circle dot implying that they needed about 15 Myr (RSG) or even more than 30 Myr (RGB) to evolve into their present stage. It might be suspected that these late-type stars do not physically belong to the Quintuplet cluster. Indeed, most of them disqualify as cluster members because their radial velocities differ too much from the cluster average. Nevertheless, five of the brightest RGB/RSG stars from the LHO catalog share the mean radial velocity of the Quintuplet, and thus remain highly suspect for being gravitationally bound members. If so, this would challenge the cluster formation and evolution scenario.
The permeation pore of K+ channels is formed by four copies of the pore domain. AtKCO3 is the only putative voltage-independent K+ channel subunit of Arabidopsis thaliana with a single pore domain. KCO3-like proteins recently emerged in evolution and, to date, have been found only in the genus Arabidopsis (A. thaliana and A. lyrata). We show that the absence of KCO3 does not cause marked changes in growth under various conditions. Only under osmotic stress we observed reduced root growth of the kco3-1 null-allele line. This phenotype was complemented by expressing a KCO3 mutant with an inactive pore, indicating that the function of KCO3 under osmotic stress does not depend on its direct ability to transport ions. Constitutively overexpressed AtKCO3 or AtKCO3::G FP are efficiently sorted to the tonoplast indicating that the protein is approved by the endoplasmic reticulum quality control. However, vacuoles isolated from transgenic plants do not have significant alterations in current density. Consistently, both AtKCO3 and AtKCO3::GFP are detected as homodimers upon velocity gradient centrifugation, an assembly state that would not allow for activity. We conclude that if AtKCO3 ever functions as a K+ channel, active tetramers are held by particularly weak interactions, are formed only in unknown specific conditions and may require partner proteins.
Context. Young supernova remnants (SNRs) exhibit narrow filaments of non-thermal X-ray emission whose widths can be limited either by electron energy losses or damping of the magnetic field.
Aims. We want to investigate whether or not different models of these filaments can be observationally tested.
Methods. Using observational parameters of four historical remnants, we calculated the filament profiles and compared the spectra of the filaments with those of the total non-thermal emission. For that purpose, we solved a one-dimensional stationary transport equation for the isotropic differential number density of the electrons.
Results. We find that the difference between the spectra of filament and total non-thermal emission above 1 keV is more pronounced in the damping model than in the energy-loss model.
Conclusions. A considerable damping of the magnetic field can result in an observable difference between the spectra of filament and total non-thermal emission, thus potentially permitting an observational discrimination between the energy-loss model and the damping model of the X-ray filaments.
The plant genome encodes at least two distinct and evolutionary conserved plastidial starch-related dikinases that phosphorylate a low percentage of glucosyl residues at the starch granule surface. Esterification of starch favours the transition of highly ordered a-glucans to a less ordered state and thereby facilitates the cleavage of interglucose bonds by hydrolases. Metabolically most important is the phosphorylation at position C6, which is catalysed by the glucan, water dikinase (GWD). The reactions mediated by recombinant wild-type GWD from Arabidopsis thaliana (AtGWD) and from Solanum tuberosum (StGWD) were studied. Two mutated proteins lacking the conserved histidine residue that is indispensible for glucan phosphorylation were also included. The wild-type GWDs consume approximately 20% more ATP than is required for glucan phosphorylation. Similarly, although incapable of phosphorylating a-glucans, the two mutated dikinase proteins are capable of degrading ATP. Thus, consumption of ATP and phosphorylation of a-glucans are not strictly coupled processes but, to some extent, occur as independent phosphotransfer reactions. As revealed by incubation of the GWDs with [gamma-33P]ATP, the consumption of ATP includes the transfer of the gamma-phosphate group to the GWD protein but this autophosphorylation does not require the conserved histidine residue. Thus, the GWD proteins possess two vicinal phosphorylation sites, both of which are transiently phosphorylated. Following autophosphorylation at both sites, native dikinases flexibly use various terminal phosphate acceptors, such as water, alpha-glucans, AMP and ADP. A model is presented describing the complex phosphotransfer reactions of GWDs as affected by the availability of the various acceptors.
The uptake of potassium ions (K+) accompanied by an acidification of the apoplasm is a prerequisite for stomatal opening. The acidification (approximately 2-2.5 pH units) is perceived by voltage-gated inward potassium channels (K-in) that then can open their pores with lower energy cost. The sensory units for extracellular pH in stomatal K-in channels are proposed to be histidines exposed to the apoplasm. However, in the Arabidopsis thaliana stomatal K-in channel KAT1, mutations in the unique histidine exposed to the solvent (His(267)) do not affect the pH dependency. We demonstrate in the present study that His(267) of the KAT1 channel cannot sense pH changes since the neighbouring residue Phe(266) shifts its pK(a) to undetectable values through a cation-pi interaction. Instead, we show that Glu(240) placed in the extracellular loop between transmembrane segments S5 and S6 is involved in the extracellular acid activation mechanism. Based on structural models we propose that this region may serve as a molecular link between the pH- and the voltage-sensor. Like Glu(240), several other titratable residues could contribute to the pH-sensor of KAT1, interact with each other and even connect such residues far away from the voltage-sensor with the gating machinery of the channel.
The Paleocene-Eocene thermal maximum represents one of the most rapid and extreme warming events in the Cenozoic. Shallow-water stratigraphic sections from the Adriatic carbonate platform offer a rare opportunity to learn about the nature of Paleocene-Eocene thermal maximum and the effects on shallow-water ecosystems. We use carbon and oxygen isotope stratigraphy, in conjunction with detailed larger benthic foraminiferal biostratigraphy, to establish a high-resolution paleoclimatic record for the Paleocene-Eocene thermal maximum. A prominent negative excursion in delta C-13 curves of bulk-rock (similar to 1 parts per thousand-3 parts per thousand), matrix (similar to 4 parts per thousand), and foraminifera (similar to 6 parts per thousand) is interpreted as the carbon isotope excursion during the Paleocene-Eocene thermal maximum. The strongly C-13-depleted delta(1)d(3)C record of our shallow-marine carbonates compared to open-marine records could result from organic matter oxidation, suggesting intensified weathering, runoff, and organic matter flux.
The Ilerdian larger benthie foraminiferal turnover is documented in detail based on high-resolution correlation with the carbon isotopic excursion. The turnover is described as a two-step process, with the first step (early Ilerdian) marked by a rapid diversification of small alveolinids and nummulitids with weak adult dimorphism, possibly as adaptations to fluctuating Paleocene-Eocene thermal maximum nutrient levels, and a second step (middle Ilerdian) characterized by a further specific diversification, increase of shell size, and well-developed adult dimorphism. Within an evolutionary scheme controlled by long-term biological processes, we argue that high seawater temperatures could have stimulated the early Ilerdian rapid specific diversification. Together, these data help elucidate the effects of global warming and associated feedbacks in shallow-water ecosystems, and by inference, could serve as an assessment analog for future changes.
Nuclear proteins play a central role in regulating gene expression. Their identification is important for understanding how the nuclear repertoire changes over time under different conditions. Nuclear proteins are often underrepresented in proteomic studies due to the frequently low abundance of proteins involved in regulatory processes. So far, only few studies describing the nuclear proteome of plant species have been published. Recently, the genome sequence of the unicellular green alga Chlamydomonas reinhardtii has been obtained and annotated, allowing the development of further detailed studies for this organism. However, a detailed description of its nuclear proteome has not been reported so far. Here, we present an analysis of the nuclear proteome of the sequenced Chlamydomonas strain cc503. Using LC-MS/MS, we identified 672 proteins from nuclei isolates with a maximum 1% peptide spectrum false discovery rate. Besides well-known proteins (e.g. histones), transcription factors and other transcriptional regulators (e.g. tubby and HMG) were identified. The presence of protein motifs in nuclear proteins was investigated by computational tools, and specific over-represented protein motifs were identified. This study provides new insights into the complexity of the nuclear environment and reveals novel putative protein targets for further studies of nuclear mechanisms.
We develop the method of Fischer-Riesz equations for general boundary value problems elliptic in the sense of Douglis-Nirenberg. To this end we reduce them to a boundary problem for a (possibly overdetermined) first order system whose classical symbol has a left inverse. For such a problem there is a uniquely determined boundary value problem which is adjoint to the given one with respect to the Green formula. On using a well elaborated theory of approximation by solutions of the adjoint problem, we find the Cauchy data of solutions of our problem.
The study of the semigroups OPn, of all orientation-preserving transformations on an n-element chain, and ORn, of all orientation-preserving or orientation-reversing transformations on an n-element chain, has began in [17] and [5]. In order to bring more insight into the subsemigroup structure of OPn and ORn, we characterize their maximal subsemigroups.
Application of crab shell chitin or pentamer chitin oligosaccharide to Arabidopsis seedlings increased tolerance to salinity in wild-type but not in knockout mutants of the LysM Receptor-Like Kinase1 (CERK1/LysM RLK1) gene, known to play a critical role in signaling defense responses induced by exogenous chitin. Arabidopsis plants overexpressing the endochitinase chit36 and hexoaminidase excy1 genes from the fungus Trichoderma asperelleoides T203 showed increased tolerance to salinity, heavy-metal stresses, and Botrytis cinerea infection. Resistant lines, overexpressing fungal chitinases at different levels, were outcrossed to lysm rlk1 mutants. Independent homozygous hybrids lost resistance to biotic and abiotic stresses, despite enhanced chitinase activity. Expression analysis of 270 stress-related genes, including those induced by reactive oxygen species (ROS) and chitin, revealed constant up-regulation (at least twofold) of 10 genes in the chitinase-overexpressing line and an additional 76 salt-induced genes whose expression was not elevated in the lysm rlk1 knockout mutant or the hybrids harboring the mutation. These findings elucidate that chitin-induced signaling mediated by LysM RLK1 receptor is not limited to biotic stress response but also encompasses abiotic-stress signaling and can be conveyed by ectopic expression of chitinases in plants.
For a sequence of Hilbert spaces and continuous linear operators the curvature is defined to be the composition of any two consecutive operators. This is modeled on the de Rham resolution of a connection on a module over an algebra. Of particular interest are those sequences for which the curvature is "small" at each step, e.g., belongs to a fixed operator ideal. In this context we elaborate the theory of Fredholm sequences and show how to introduce the Lefschetz number.
Although intensification of toxic cyanobacterial blooms over the last decade is a matter of growing concern due to bloom impact on water quality, the biological role of most of the toxins produced is not known. In this critical review we focus primarily on the biological role of two toxins, microcystins and cylindrospermopsin, in inter- and intra-species communication and in nutrient acquisition. We examine the experimental evidence supporting some of the dogmas in the field and raise several open questions to be dealt with in future research. We do not discuss the health and environmental implications of toxin presence in the water body.
Program behavior that relies on contextual information, such as physical location or network accessibility, is common in today's applications, yet its representation is not sufficiently supported by programming languages. With context-oriented programming (COP), such context-dependent behavioral variations can be explicitly modularized and dynamically activated. In general, COP could be used to manage any context-specific behavior. However, its contemporary realizations limit the control of dynamic adaptation. This, in turn, limits the interaction of COP's adaptation mechanisms with widely used architectures, such as event-based, mobile, and distributed programming. The JCop programming language extends Java with language constructs for context-oriented programming and additionally provides a domain-specific aspect language for declarative control over runtime adaptations. As a result, these redesigned implementations are more concise and better modularized than their counterparts using plain COP. JCop's main features have been described in our previous publications. However, a complete language specification has not been presented so far. This report presents the entire JCop language including the syntax and semantics of its new language constructs.
The interplay of autonomy goals and spousal support a prospective study with couples facing cancer
(2012)
In this study, we analyzed the influence of soil mineral characteristics (e. g., clay concentration and mineralogical composition, iron and aluminum oxide concentration and crystallinity, specific surface area, and exchangeable cation concentration) on (i) organic carbon (OC) content (kg m(-2)) and (ii) the concentration (g kg(-1)), composition, and stability of the mineral-associated organic matter (OM) of arable and forest topsoils. We selected seven soil types with different mineral characteristics for this study. For each soil type, samples were taken from topsoils of a deciduous forest and an adjacent arable site. The arable and forest sites have been used continuously for more than 100 years. Na-pyrophosphate soluble OM fractions (OM(PY)), representing mineral-associated OM, were extracted, analyzed for OC and C-14 concentrations, and characterized by FTIR spectroscopy. For the forest and arable topsoils, a linear relationship was found between the OC content and exchangeable Ca. For the arable topsoils (pH 6.7-7.5), correlation analyses indicated that the OCPY concentration increased with an increase in oxalate soluble Fe and Al, exchangeable Ca, and Na-pyrophosphate soluble Mg and Fe concentrations. The stability of OM(PY) determined by the C-14 measurements of the near-neutral arable topsoils was shown to increase with the specific surface area and the concentration of exchangeable Ca. For the acidic forest topsoils (pH < 5), the stability of OM(PY) was found to increase as the pH, and the concentration of C=O groups and Na-pyrophosphate soluble Mg increase.
Aldehyde oxidase (AO) is a complex molybdo-flavoprotein that belongs to the xanthine oxidase family. AO is active as a homodimer, and each 150-kDa monomer binds two distinct [2Fe2S] clusters, FAD, and the molybdenum cofactor. AO has an important role in the metabolism of drugs based on its broad substrate specificity oxidizing aromatic aza-heterocycles, for example, N-1-methylnicotinamide and N-methylphthalazinium, or aldehydes, such as benzaldehyde, retinal, and vanillin. Sequencing the 35 coding exons of the human AOX1 gene in a sample of 180 Italian individuals led to the identification of relatively frequent, synonymous, missense and nonsense single-nucleotide polymorphisms (SNPs). Human aldehyde oxidase (hAOX1) was purified after heterologous expression in Escherichia coli. The recombinant protein was obtained with a purity of 95% and a yield of 50 mu g/l E. coli culture. Site-directed mutagenesis of the hAOX1 cDNA allowed the purification of protein variants bearing the amino acid changes R802C, R921H, N1135S, and H1297R, which correspond to some of the identified SNPs. The hAOX1 variants were purified and compared with the wild-type protein relative to activity, oligomerization state, and metal content. Our data show that the mutation of each amino acid residue has a variable impact on the ability of hAOX1 to metabolize selected substrates. Thus, the human population is characterized by the presence of functionally inactive hAOX1 allelic variants as well as variants encoding enzymes with different catalytic activities. Our results indicate that the presence of these allelic variants should be considered for the design of future drugs.
Effects of food quality and quantity on consumers are neither independent nor interchangeable. Although consumer growth and reproduction show strong variation in relation to both food quality and quantity, the effects of food quality or food quantity have usually been studied in isolation. In two experiments, we studied the growth and reproduction in three filter-feeding freshwater zooplankton species, i.e. Daphnia galeata x hyalina, D. pulicaria and D. magna, on their algal food (Scenedesmus obliquus), varying in carbon to phosphorus (C:P) ratios and quantities (concentrations). In the first experiment, we found a strong positive effect of the phosphorus content of food on growth of Daphnia, both in their early and late juvenile development. Variation in the relationship between the P-content of animals and their growth rate reflected interspecific differences in nutrient requirements. Although growth rates typically decreased as development neared maturation, this did not affect these species-specific couplings between growth rate and Daphnia P-content. In the second experiment, we examined the effects of food quality on Daphnia growth at different levels of food quantity. With the same decrease in P-content of food, species with higher estimated P-content at zero growth showed a larger increase in threshold food concentrations (i.e. food concentration sufficient to meet metabolic requirements but not growth). These results suggest that physiological processes such as maintenance and growth may in combination explain effects of food quality and quantity on consumers. Our study shows that differences in response to variation in food quality and quantity exist between species. As a consequence, species-specific effects of food quality on consumer growth will also determine how species deal with varying food levels, which has implications for resource-consumer interactions.
In this paper, we provide a comprehensive multivariate cointegration analysis of three parts of the steam coal value chain - export, transport and import prices. The analysis is based on a rich dataset of international coal prices: in particular, we combine data on steam coal prices with freight rates, covering the period December 2001 until August 2009 at weekly frequency. We then test whether the demand and supply side components of steam coal trade are consistently integrated with one another. In addition, export and import prices as well as freight rates for individual trading routes, across regions and globally are combined. We find evidence of significant yet incomplete integration. We also find heterogeneous short-term dynamics of individual markets. Furthermore, we examine whether logistics enter coal price dynamics through transportation costs, which are mainly determined by oil prices. Our results suggest that this is generally not the case.
The reaction of the German labor market to the Great Recession 2008/09 was relatively mild – especially compared to other countries. The reason lies not only in the specific type of the recession – which was favorable for the German economy structure – but also in a series of labor market reforms initiated between 2002 and 2005 altering, inter alia, labor supply incentives. However, irrespective of the mild response to the Great Recession, there are a number of substantial future challenges the German labor market will soon have to face. Female labor supply still lies well below that of other countries and a massive demographic change over the next 50 years will have substantial effects on labor supply as well as the pension system. In addition, due to a skill-biased technological change over the next decades, firms will face problems of finding employees with adequate skills. The aim of this paper is threefold. First, we outline why the German labor market reacted in such a mild fashion, describe current economic trends of the labor market in light of general trends in the European Union, and reveal some of the main associated challenges. Thereafter, the paper analyzes recent reforms of the main institutional settings of the labor market which influence labor supply. Finally, based on the status quo of these institutional settings, the paper gives a brief overview of strategies to combat adequately the challenges in terms of labor supply and to ensure economic growth in the future.
The Garzn Complex of the Garzn Massif in SW Colombia is composed of the Vergel Granulite Unit (VG) and the Las Margaritas Migmatite Unit (LMM). Previous studies reveal peak temperature conditions for the VG of about 740 A degrees C. The present study considers the remarkable exsolution phenomena in feldspars and pyroxenes and titanium-in-quartz thermometry. Recalculated ternary feldspar compositions indicate temperatures around 900-1,000 A degrees C just at or above the ultra-high temperature-metamorphism (UHTM) boundary of granulites. The calculated temperatures range of exsolved ortho- and clinopyroxenes also supports the existence of an UHTM event. In addition, titanium-in-quartz thermometry points towards ultra-high temperatures. It is the first known UHTM crustal segment in the northern part of South America. Although a mean geothermal gradient of ca 38 A degrees C km(-1) could imply additional heat supply in the lower crust controlling this extreme of peak metamorphism, an alternative model is suggested. The formation of the Vergel Granulite Unit is supposed to be formed in a continental back-arc environment with a thinned and weakened crust behind a magmatic arc (Guapotn-Mancagua Gneiss) followed by collision. In contrast, rocks of the adjacent Las Margaritas Migmatite Unit display "normal" granulite facies temperatures and are formed in a colder lower crust outside the arc, preserved by the Guapotn-Mancagu Gneiss. Back-arc formation was followed by inversion and thickening of the basin. The three units that form the modern-day Garzn Massif, were juxtaposed upon each other during collision (at ca. 1,000 Ma) and exhumation. The collision leading to the deformation of the studied area is part of the Grenville orogeny leading to the amalgamation of Rodinia.
The Galactic WC stars Stellar parameters from spectral analyses indicate a new evolutionary sequence
(2012)
Context. The life cycles of massive stars from the main sequence to their explosion as supernovae or gamma ray bursts are not yet fully clear, and the empirical results from spectral analyses are partly in conflict with current evolutionary models. The spectral analysis of Wolf-Rayet stars requires the detailed modeling of expanding stellar atmospheres in non-LTE. The Galactic WN stars have been comprehensively analyzed with such models of the latest stage of sophistication, while a similarly comprehensive study of the Galactic WC sample remains undone.
Aims. We aim to establish the stellar parameters and mass-loss rates of the Galactic WC stars. These data provide the empirical basis of studies of (i) the role of WC stars in the evolution of massive stars, (ii) the wind-driving mechanisms, and (iii) the feedback of WC stars as input to models of the chemical and dynamical evolution of galaxies.
Methods. We analyze the nearly complete sample of un-obscured Galactic WC stars, using optical spectra as well as ultraviolet spectra when available. The observations are fitted with theoretical spectra, using the Potsdam Wolf-Rayet (PoWR) model atmosphere code. A large grid of line-blanked models has been established for the range of WC subtypes WC4 - WC8, and smaller grids for the WC9 parameter domain. Both WO stars and WN/WC transit types are also analyzed using special models.
Results. Stellar and atmospheric parameters are derived for more than 50 Galactic WC and two WO stars, covering almost the whole Galactic WC population as far as the stars are single, and un-obscured in the visual. In the Hertzsprung-Russell diagram, the WC stars reside between the hydrogen and the helium zero-age main sequences, having luminosities L from 10(4.9) to 10(5.6) L-circle dot. The mass-loss rates scale very tightly with L-0.8. The two WO stars in our sample turn out to be outstandingly hot (approximate to 200 kK) and do not fit into the WC scheme.
Conclusions. By comparing the empirical WC positions in the Hertzsprung-Russell diagram with evolutionary models, and from recent supernova statistics, we conclude that WC stars have evolved from initial masses between 20 solar masses and 45 M-circle dot. In contrast to previous assumptions, it seems that WC stars in general do not descend from the most massive stars. Only the WO stars might stem from progenitors that have been initially more massive than 45 M-circle dot.
The number of patients seeking treatment in emergency departments is rising, although many governments are seeking to reduce expenditure on health. Emergency departments must achieve more with the same resources or perform the same functions with fewer resources. Patients demand higher emergency clinical care quality, with low waiting times viewed as a key quality criterion by many patients. The objective of this study was to create an improved working system in emergency departments that cuts patient waiting times for first specialty physician contact. Techniques from industrial flow management were applied to the working process of an emergency department and the concept was named 'First View.' A total of 3269 patient contacts using the First View Concept during a treatment month showed statistical significance. Before introduction, a total 3230 patients in a comparative treatment month had a median waiting time before the first doctor contact of 47.6 min, a first quartile waiting time of 36.1 min, and a third quartile waiting time of 62.7 min. After introduction, 3269 patients had a median waiting time before first specialty physician contact of 11.2 min, a first quartile waiting time of 9.1 min, and a third quartile waiting time of 15.2 min. Industrial flow concepts can achieve significant improvements in emergency department workflows in countries in which sufficient numbers of specialty physicians are available. More attention to the organization of emergency department working processes is needed, especially involving lean management.
Aldehyde oxidases (AOXs) are homodimeric proteins belonging to the xanthine oxidase family of molybdenum-containing enzymes. Each 150-kDa monomer contains a FAD redox cofactor, two spectroscopically distinct [2Fe-2S] clusters, and a molybdenum cofactor located within the protein active site. AOXs are characterized by broad range substrate specificity, oxidizing different aldehydes and aromatic N-heterocycles. Despite increasing recognition of its role in the metabolism of drugs and xenobiotics, the physiological function of the protein is still largely unknown. We have crystallized and solved the crystal structure of mouse liver aldehyde oxidase 3 to 2.9 angstrom. This is the first mammalian AOX whose structure has been solved. The structure provides important insights into the protein active center and further evidence on the catalytic differences characterizing AOX and xanthine oxidoreductase. The mouse liver aldehyde oxidase 3 three-dimensional structure combined with kinetic, mutagenesis data, molecular docking, and molecular dynamics studies make a decisive contribution to understand the molecular basis of its rather broad substrate specificity.
Today, diverse communities of zooxanthellate corals thrive, but do not build reef, under a wide range of environmental conditions. In these settings they inhabit natural bottom communities, sometimes forming patch-reefs, coral carpets and knobs. Episodes in the fossil record, characterized by limited coral-reef development but widespread occurrence of coral-bearing carbonates, may represent the fossil analogs of these non-reef building, zooxanthellate coral communities. If so, the study of these corals could have valuable implications for paleoenvironmental reconstructions. Here we focus on the evolution of early Paleogene corals as a fossil example of coral communities mainly composed by zooxanthellate corals (or likely zooxanthellate), commonly occurring within carbonate biofacies and with relatively high diversity but with a limited bioconstructional potential as testified by the reduced record of coral reefs. We correlate changes of bioconstructional potential and community compositions of these fossil corals with the main ecological/environmental conditions at that time. The early Paleogene greenhouse climate was characterized by relatively short pulses of warming with the most prominent occurring at the Paleocene-Eocene boundary (PETM event), associated with high weathering rates, nutrient fluxes, and pCO(2) levels. A synthesis of coral occurrences integrated with our data from the Adriatic Carbonate Platform (SW Slovenia) and the Minervois region (SW France), provides evidence for temporal changes in the reef-building capacity of corals associated with a shift in community composition toward forms adapted to tolerate deteriorating sea-water conditions. During the middle Paleocene coral-algal patch reefs and barrier reefs occurred from shallow-water settings, locally with reef-crest structures. A first shift can be traced from middle Paleocene to late Paleocene, with small coral-algal patch reefs and coral-bearing mounds development in shallow to intermediate water depths. In these mounds corals were highly subordinated as bioconstructors to other groups tolerant to higher levels of trophic resources (calcareous red algae, encrusting foraminifera, microbes, and sponges). A second shift occurred at the onset of the early Eocene with a further reduction of coral framework-building capacity. These coral communities mainly formed knobs in shallow-water, turbid settings associated with abundant foraminiferal deposits. We suggest that environmental conditions other than high temperature determined a combination of interrelated stressors that limited the coral-reef construction. A continuous enhancement of sediment load/nutrients combined with geochemical changes of ocean waters likely displaced corals as the main bioconstructors during the late Paleocene-early Eocene times. Nonetheless, these conditions did not affect the capacity of some corals to colonize the substrate, maintain biodiversity, and act as locally important carbonate-sediment producers, suggesting broad environmental tolerance limits of various species of corals. The implications of this study include clues as to how both ancient and modern zooxanthellate corals could respond to changing climate.
This thesis investigates the gradient flow of Dirac-harmonic maps. Dirac-harmonic maps are critical points of an energy functional that is motivated from supersymmetric field theories. The critical points of this energy functional couple the equation for harmonic maps with spinor fields. At present, many analytical properties of Dirac-harmonic maps are known, but a general existence result is still missing. In this thesis the existence question is studied using the evolution equations for a regularized version of Dirac-harmonic maps. Since the energy functional for Dirac-harmonic maps is unbounded from below the method of the gradient flow cannot be applied directly. Thus, we first of all consider a regularization prescription for Dirac-harmonic maps and then study the gradient flow. Chapter 1 gives some background material on harmonic maps/harmonic spinors and summarizes the current known results about Dirac-harmonic maps. Chapter 2 introduces the notion of Dirac-harmonic maps in detail and presents a regularization prescription for Dirac-harmonic maps. In Chapter 3 the evolution equations for regularized Dirac-harmonic maps are introduced. In addition, the evolution of certain energies is discussed. Moreover, the existence of a short-time solution to the evolution equations is established. Chapter 4 analyzes the evolution equations in the case that the domain manifold is a closed curve. Here, the existence of a smooth long-time solution is proven. Moreover, for the regularization being large enough, it is shown that the evolution equations converge to a regularized Dirac-harmonic map. Finally, it is discussed in which sense the regularization can be removed. In Chapter 5 the evolution equations are studied when the domain manifold is a closed Riemmannian spin surface. For the regularization being large enough, the existence of a global weak solution, which is smooth away from finitely many singularities is proven. It is shown that the evolution equations converge weakly to a regularized Dirac-harmonic map. In addition, it is discussed if the regularization can be removed in this case.
The EVE curriculum framework
(2012)
The Eu Timescape
(2012)
This article deals with Spanish modal adverbs and verbs of cognitive attitude (Capelli 2007) and their epistemic and/or evidential use. The article is based upon the hypothesis that the study of the use of these linguistic devices has to be highly context-sensitive, as it is not always (only) the sentence level that has to be looked at if one wants to find out whether a certain adverb or verb of cognitive attitude is used evidentially or epistemically. In this article, therefore, the context is used to determine which meaning aspects of an element are encoded and which are contributed by the context. The data were retrieved from the daily newspaper El Pais. Nevertheless, the present study is not a quantitative one, but rather a qualitative study. My corpus analysis indicates that it is not possible to differentiate between the linguistic categories of evidentiality and epistemic modality in every case, although it indeed is possible in the vast majority of cases. In verbs of cognitive attitude, evidentiality and epistemic modality seem to be two interwoven categories, while concerning modal adverbs it is usually possible to separate the categories and to distinguish between the different subtypes of evidentiality such as visual evidence, hearsay and inference.
This article deals with Spanish modal adverbs and verbs of cognitive attitude (Capelli 2007) and their epistemic and/or evidential use. The article is based upon the hypothesis that the study of the use of these linguistic devices has to be highly context-sensitive, as it is not always (only) the sentence level that has to be looked at if one wants to find out whether a certain adverb or verb of cognitive attitude is used evidentially or epistemically. In this article, therefore, the context is used to determine which meaning aspects of an element are encoded and which are contributed by the context. The data were retrieved from the daily newspaper El País. Nevertheless, the present study is not a quantitative one, but rather a qualitative study. My corpus analysis indicates that it is not possible to differentiate between the linguistic categories of evidentiality and epistemic modality in every case, although it indeed is possible in the vast majority of cases. In verbs of cognitive attitude, evidentiality and epistemic modality seem to be two interwoven categories, while concerning modal adverbs it is usually possible to separate the categories and to distinguish between the different subtypes of evidentiality such as visual evidence, hearsay and inference.
Two studies explored the role of pleasant music in buffering the adverse effects of provocation. In the first study, 111 participants listened to aversive, pleasant, or no music before receiving a provocation and completing a measure of aggressive behavior. Participants exposed to pleasant music reported more positive mood. Those in the aversive music condition reported more negative mood than did those in the no-music control condition. The more positive the music-induced mood, the less anger was experienced and aggressive behavior was shown after provocation. In Study 2 (N = 142), listening to pleasant music reduced anger following provocation, compared to aversive music and a no-music control condition. Pleasant music also increased response latencies in recognizing aggressive words after provocation.
Background/Purpose
Muscular reflex responses of the lower extremities to sudden gait disturbances are related to postural stability and injury risk. Chronic ankle instability (CAI) has shown to affect activities related to the distal leg muscles while walking. Its effects on proximal muscle activities of the leg, both for the injured- (IN) and uninjured-side (NON), remain unclear. Therefore, the aim was to compare the difference of the motor control strategy in ipsilateral and contralateral proximal joints while unperturbed walking and perturbed walking between individuals with CAI and matched controls.
Materials and methods
In a cross-sectional study, 13 participants with unilateral CAI and 13 controls (CON) walked on a split-belt treadmill with and without random left- and right-sided perturbations. EMG amplitudes of muscles at lower extremities were analyzed 200 ms after perturbations, 200 ms before, and 100 ms after (Post100) heel contact while walking. Onset latencies were analyzed at heel contacts and after perturbations. Statistical significance was set at alpha≤0.05 and 95% confidence intervals were applied to determine group differences. Cohen’s d effect sizes were calculated to evaluate the extent of differences.
Results
Participants with CAI showed increased EMG amplitudes for NON-rectus abdominus at Post100 and shorter latencies for IN-gluteus maximus after heel contact compared to CON (p<0.05). Overall, leg muscles (rectus femoris, biceps femoris, and gluteus medius) activated earlier and less bilaterally (d = 0.30–0.88) and trunk muscles (bilateral rectus abdominus and NON-erector spinae) activated earlier and more for the CAI group than CON group (d = 0.33–1.09).
Conclusion
Unilateral CAI alters the pattern of the motor control strategy around proximal joints bilaterally. Neuromuscular training for the muscles, which alters motor control strategy because of CAI, could be taken into consideration when planning rehabilitation for CAI.
The Dutch school system
(2012)
Prior research has shown that quantity of schooling affects the development of intelligence in childhood and adolescence. However, it is still debated whether other aspects of schooling-such as ability tracking or, more generally, school quality-can also influence intelligence. In this study, the authors analyzed intelligence gains in academic- and vocational-track schools in Germany, testing for differential effects of school quality (academic vs. vocational track) on psychometric intelligence. Longitudinal data were obtained from a sample of N = 1,038 Grade 7 and 10 students in 49 schools. A nonverbal reasoning test was used as an indicator of general psychometric intelligence, and relevant psychological and social background variables were included in the analyses. Propensity score matching was used to control for selection bias. Results showed a positive effect of attending the academic track.
Dealing with spam is very costly, and many organizations have tried to reduce spam-related costs by installing spam filters. Relying on modern econometric methods to reduce the selection bias of installing a spam filter, we use a unique data setting implemented at a German university to measure the costs associated with spam and the costs savings of spam filters. Our methodological framework accounts for effect heterogeneity and can be easily used to estimate the effect of other IS technologies implemented in organizations.
The majority of costs stem from the time that employees spend identifying and deleting spam, amounting to an average of approximately five minutes per employee per day. Our analysis, which accounts for selection bias, finds that the installation of a spam filter reduces these costs by roughly one third. Failing to account for the selection bias would lead to a result that suggests that installing a spam filter does not reduce working time losses.
However, cost savings only occur when the spam burden is high, indicating that spam filters do not necessarily reduce costs and are therefore no universal remedy. The analysis further shows that spam filters alone are a countermeasure against spam that exhibits only limited effectiveness because they only reduce costs by one third.
In Central and NW Europe, the transition from the Permian to the Triassic (i.e., the Zechstein-Buntsandstein boundary interval) is developed mainly in red bed facies. This continental sedimentary succession is marked by relatively high sedimentation rates providing a high temporal resolution favorable for magnetic polarity stratigraphy. Here, we present a Zechstein to Lower Buntsandstein magnetostratigraphy obtained from the c. 100 m thick Everdingen-1 core from the Netherlands. Seven magnetozones (EV1n to EV4n) and five submagnetozones (EV1n.1r to EV3r.1n) have been delineated. The Everdingen-1 magnetostratigraphy has been integrated into the well-established high-resolution Zechstein-Buntsandstein stratigraphic framework, and verifies the geomagnetic polarity record from Central Germany. This confirms the hypothesis of nearly synchronous base-level cycles within the interior of the Central European Basin. These cycles are related to solar-induced similar to 100 ka eccentricity cycles. The most distinctive feature of the Everdingen-1 magnetostratigraphy is a transition from a thin reverse to a thick dominantly normal magnetic polarity interval. This reversal predates both the terrestrial mass extinction, which is indicated by a palynofloral turnover and a major sediment provenance change at the base of the Buntsandstein, and the marine Permian-Triassic Boundary (PTB). The PTB is located within the lowermost Buntsandstein and is approximated by the last occurrence of the conchostracan Falsisca postera and a negative excursion in the carbon isotope record. According to the Buntsandstein cyclostratigraphy, the R/N reversal predates the marine end-Permian extinction event by about 0.1 Ma and the marine biostratigraphic PTB by about 0.2 Ma. The thick normal magnetozone is estimated to have lasted c. 700 ka, and roughly coincides with the main phase of Siberian Trap volcanism.
Completely positive, trace preserving (CPT) maps and Lindblad master equations are both widely used to describe the dynamics of open quantum systems. The connection between these two descriptions is a classic topic in mathematical physics. One direction was solved by the now famous result due to Lindblad, Kossakowski, Gorini and Sudarshan, who gave a complete characterisation of the master equations that generate completely positive semi-groups. However, the other direction has remained open: given a CPT map, is there a Lindblad master equation that generates it (and if so, can we find its form)? This is sometimes known as the Markovianity problem. Physically, it is asking how one can deduce underlying physical processes from experimental observations.
We give a complexity theoretic answer to this problem: it is NP-hard. We also give an explicit algorithm that reduces the problem to integer semi-definite programming, a well-known NP problem. Together, these results imply that resolving the question of which CPT maps can be generated by master equations is tantamount to solving P = NP: any efficiently computable criterion for Markovianity would imply P = NP; whereas a proof that P = NP would imply that our algorithm already gives an efficiently computable criterion. Thus, unless P does equal NP, there cannot exist any simple criterion for determining when a CPT map has a master equation description.
However, we also show that if the system dimension is fixed (relevant for current quantum process tomography experiments), then our algorithm scales efficiently in the required precision, allowing an underlying Lindblad master equation to be determined efficiently from even a single snapshot in this case.
Our work also leads to similar complexity-theoretic answers to a related long-standing open problem in probability theory.
The cognitive sociolinguistic approach to the lexicon of Cameroon English and other world englishes
(2012)
A growing literature has suggested that processing of visual information presented near the hands is facilitated. In this study, we investigated whether the near-hands superiority effect also occurs with the hands moving. In two experiments, participants performed a cyclical bimanual movement task requiring concurrent visual identification of briefly presented letters. For both the static and dynamic hand conditions, the results showed improved letter recognition performance with the hands closer to the stimuli. The finding that the encoding advantage for near-hand stimuli also occurred with the hands moving suggests that the effect is regulated in real time, in accordance with the concept of a bimodal neural system that dynamically updates hand position in external space.
The closer the better
(2012)
A growing literature has suggested that processing of visual information presented near the hands is facilitated. In this study, we investigated whether the near-hands superiority effect also occurs with the hands moving. In two experiments, participants performed a cyclical bimanual movement task requiring concurrent visual identification of briefly presented letters. For both the static and dynamic hand conditions, the results showed improved letter recognition performance with the hands closer to the stimuli. The finding that the encoding advantage for near-hand stimuli also occurred with the hands moving suggests that the effect is regulated in real time, in accordance with the concept of a bimodal neural system that dynamically updates hand position in external space.
The chemistry of water on alpha-alumina kinetics and nuclear quantum effects from first principles
(2012)
Water adsorption on an alumina (alpha-Al2O3) surface is studied here from first principles using periodic density functional theory in the generalized gradient approximation. Two different coverage regimes, low and high, are considered. For the low-coverage regime (with a coverage of 1/4 with respect to the number of coordinatively unsaturated Al sites), possible reactions at the surface such as dissociation, rotation, and diffusion of water and its fragments are investigated, using first principles thermodynamics and kinetics. A microkinetic model is set up with rates calculated from Eyring's transition state theory in order to cover a wide range of time scales. Special emphasis of this study is on the magnitude of quantum effects and on anharmonic corrections, particularly for reactions and dynamics. These have often been neglected in the past for water/alumina systems but can influence the system. This is particularly true for processes involving hydrogen atoms, where, for example, tunneling corrections to reaction rates are found to be important even at room temperature. For a higher-coverage regime (with a coverage of 2 ML), hydrogen dynamics becomes even more complex and is characterized, e.g., by concerted atom motion, strong anharmonicity, and delocalization. In this regime, classical molecular dynamics becomes questionable as well as quantum mechanical treatments based on the harmonic approximation.
Assuming that liquid iron alloy from the outer core interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. Iron-silicate mixing would lead to regions of partial melting with higher density which in turn reduces the velocity of seismic waves. On the basis of the calculation and interpretation of short-period synthetic seismograms, using the reflectivity and Gauss Beam method, a model space is evaluated for these ultra-low velocity zones (ULVZs). The aim of this thesis is to analyse the behaviour of PcP between 10° and 40° source distance for such models using different velocity and density configurations. Furthermore, the resolution limits of seismic data are discussed. The influence of the assumed layer thickness, dominant source frequency and ULVZ topography are analysed. The Gräfenberg and NORSAR arrays are then used to investigate PcP from deep earthquakes and nuclear explosions. The seismic resolution of an ULVZ is limited both for velocity and density contrasts and layer thicknesses. Even a very thin global core-mantle transition zone (CMTZ), rather than a discrete boundary and also with strong impedance contrasts, seems possible: If no precursor is observable but the PcP_model /PcP_smooth amplitude reduction amounts to more than 10%, a very thin ULVZ of 5 km with a first-order discontinuity may exist. Otherwise, if amplitude reductions of less than 10% are obtained, this could indicate either a moderate, thin ULVZ or a gradient mantle-side CMTZ. Synthetic computations reveal notable amplitude variations as function of the distance and the impedance contrasts. Thereby a primary density effect in the very steep-angle range and a pronounced velocity dependency in the wide-angle region can be predicted. In view of the modelled findings, there is evidence for a 10 to 13.5 km thick ULVZ 600 km south-eastern of Moscow with a NW-SE extension of about 450 km. Here a single specific assumption about the velocity and density anomaly is not possible. This is in agreement with the synthetic results in which several models create similar amplitude-waveform characteristics. For example, a ULVZ model with contrasts of -5% VP , -15% VS and +5% density explain the measured PcP amplitudes. Moreover, below SW Finland and NNW of the Caspian Sea a CMB topography can be assumed. The amplitude measurements indicate a wavelength of 200 km and a height of 1 km topography, previously also shown in the study by Kampfmann and Müller (1989). Better constraints might be provided by a joined analysis of seismological data, mineralogical experiments and geodynamic modelling.
The processing, representation, and perception of bodily signals (interoception) plays an important role for human behavior. Theories of embodied cognition hold that higher cognitive processes operate on perceptual symbols and that concept use involves reactivations of the sensory-motor states that occur during experience with the world. Similarly, activation of interoceptive representations and meta-representations of bodily signals supporting interoceptive awareness are profoundly associated with emotional experience and cognitive functions. This article gives an overview over present findings and models on interoception and mechanisms of embodiment and highlights its relevance for disorders that are suggested to represent a translation deficit of bodily states into subjective feelings and self-awareness.
The blowfly salivary gland - A model system for analyzing the regulation of plasma membrane V-ATPase
(2012)
Vacuolar H+-ATPases (V-ATPases) are heteromultimeric proteins that use the energy of ATP hydrolysis for the electrogenic transport of protons across membranes. They are common to all eukaryotic cells and are located in the plasma membrane or in membranes of acid organelles. In many insect epithelia, V-ATPase molecules reside in large numbers in the apical plasma membrane and create an electrochemical proton gradient that is used for the acidification or alkalinization of the extracellular space, the secretion or reabsorption of ions and fluids, the import of nutrients, and diverse other cellular activities. Here, we summarize our results on the functions and regulation of V-ATPase in the tubular salivary gland of the blowfly Calliphora vicina. In this gland, V-ATPase activity energizes the secretion of a KCl-rich saliva in response to the neurohormone serotonin (5-HT). Because of particular morphological and physiological features, the blowfly salivary glands are a superior and exemplary system for the analysis of the intracellular signaling pathways and mechanisms that modulate V-ATPase activity and solute transport in an insect epithelium.
The aromatic peroxygenase (APO; EC 1.11.2.1) from the agraric basidomycete Marasmius rotula (MroAPO) immobilized at the chitosan-capped gold-nanoparticle-modified glassy carbon electrode displayed a pair of redox peaks with a midpoint potential of -278.5 mV vs. AgCl/AgCl (1 M KCl) for the Fe(2+)/Fe(3+) redox couple of the heme-thiolate-containing protein. MroAPO oxidizes aromatic substrates such as aniline, p-aminophenol, hydroquinone, resorcinol, catechol, and paracetamol by means of hydrogen peroxide. The substrate spectrum overlaps with those of cytochrome P450s and plant peroxidases which are relevant in environmental analysis and drug monitoring. In M. rotula peroxygenase-based enzyme electrodes, the signal is generated by the reduction of electrode-active reaction products (e.g., p-benzoquinone and p-quinoneimine) with electro-enzymatic recycling of the analyte. In these enzyme electrodes, the signal reflects the conversion of all substrates thus representing an overall parameter in complex media. The performance of these sensors and their further development are discussed.
To investigate how preschoolers acquire a tool use strategy and how they adapt their tool use to a changed situation, 2- to 4-year-olds were asked to retrieve chips from a transparent box with a rod, either by stabbing and lifting through a top opening or by pushing through a front and a back opening. In both conditions, about 40% of the children acquired effective tool use by individual learning, and 90% of the other children learned this by observing only one demonstration. When confronted with a changed situation (i.e., previous opening covered, alternative opening uncovered), children perseverated with the recently learned, but now ineffective tool use strategy. Neither age nor acquisition type of the first strategy affected preschoolers' perseverations. Results indicate that prior tool use experiences have differential effects in situations that require either transferring known functions to novel objects or using a familiar tool for an alternative purpose.
The 2010 very high energy gamma-ray flare and 10 years ofmulti-wavelength oservations of M 87
(2012)
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of tau(rise)(d) = (1.69 +/- 0.30) days and tau(decay)(d) = (0.611 +/- 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (similar to day), peak fluxes (Phi(>0.35 TeV) similar or equal to (1-3) x 10(-11) photons cm(-2) s(-1)), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken similar to 3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core (flux increased by factor similar to 2; variability timescale <2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubble Space Telescope, Liverpool Telescope, Very Large Array, and European VLBI Network, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified. In the outer kiloparsec jet region, in particular in HST-1, no enhanced MWL activity was detected in 2008 and 2010, disfavoring it as the origin of the VHE flares during these years. Shortly after two of the three flares (2008 and 2010), the X-ray core was observed to be at a higher flux level than its characteristic range (determined from more than 60 monitoring observations: 2002-2009). In 2005, the strong flux dominance of HST-1 could have suppressed the detection of such a feature. Published models for VHE gamma-ray emission from M 87 are reviewed in the light of the new data.
This study is based on an editorial report, which was presented at the 2009 working conference »Alexander von Humboldt and the Hemisphere« at Vanderbilt University (Nashville, TN). It demonstrates the textual genesis of Humboldt’s writings on Cuba through examples, which were obtained from a detailed text comparison of the three existing »original« versions of Humboldt’s Essai politique sur l’île de Cuba. The collation was part of a larger strategy to regain philological ground for the »Humboldt in English« (HiE) project. Since 2007 and funded with grants from the National Endowment for the Humanities, the Alexander von Humboldt-Foundation, and the Gerda Henkel Foundation, the US-German research team behind HiE has been working on new and unabridged translations and critical editions of three of Humboldt’s most significant texts from his American oeuvre.1 The following observations will outline the most important results of this collation effort as a complementary contribution to the recent release of the HiE project’s first volume, The Political Essay on the Island of Cuba (Chicago University Press 2011), edited by Vera M. Kutzinski and Ottmar Ette.
Ionic liquids (ILs) on the basis of metal containing anions and/or cations are of interest for a variety of technical applications e.g., synthesis of particles, magnetic or thermochromic materials. We present the synthesis and the results of electron paramagnetic resonance (EPR) spectroscopic analyses of a series of some new potential ionic liquids based on tetrachloridocuprates(II), [CuCl4](2-), with different sterically demanding cations: hexadecyltrimethylammonium 1, tetradecyltrimethylammonium 2, tetrabutylammonium 3 and benzyltriethylammonium 4. The cations in the new compounds were used to achieve a reasonable separation of the paramagnetic Cu(II) ions for EPR spectroscopy. The EPR hyperfine structure was not resolved. This is due to the exchange broadening, resulting from still incomplete separation of the paramagnetic Cu(II) centers. Nevertheless, the principal values of the electron Zeemann tensor (g parallel to and g perpendicular to) of the complexes could be determined. Even though the solid substances show slightly different colors, the UV/Vis spectra are nearly identical, indicating structural changes of the tetrachloridocuprate moieties between solid state and solution. The complexes have a promising potential e.g., as high temperature ionic liquids, as precursors for the formation of copper chloride particles or as catalytic paramagnetic ionic liquids.
In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predator-prey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching efficiencies of insects. To overcome logistic constraints of field experiments, we used a successfully validated simulation model to investigate plant responses to removal of herbivores and their enemies. Consistent with our predictions, instability measured by herbivore-induced plant mortality increased with increasing land use intensity. Simultaneously, the balance between herbivores and natural enemies turned increasingly towards herbivore dominance and natural enemy failure. Under natural conditions, there were more frequently significant effects of belowground herbivores and their natural enemies on plant performance, whereas there were more aboveground effects in agroecosystems. This result was partly due to the "boom-bust'' behavior of the shoot herbivore population. Plant responses to herbivore or natural enemy removal were much more abrupt than the imposed smooth land use intensity gradient. This may be due to the presence of multiple trophic levels aboveground and belowground. Our model suggests that destabilization and extinction are more likely to occur in agroecosystems than in natural communities, but the shape of the relationship is nonlinear under the influence of multiple trophic interactions. Citation: Meyer KM, Vos M, Mooij WM, Hol WHG, Termorshuizen AJ, et al. (2012) Testing the Paradox of Enrichment along a Land Use Gradient in a Multitrophic Aboveground and Belowground Community.
Large research initiatives such as the Global Earthquake Model (GEM) or the Seismic HAzard haRmonization in Europe (SHARE) projects concentrate a great collaborative effort on defining a global standard for seismic hazard estimations. In this context, there is an increasing need for identifying ground-motion prediction equations (GMPEs) that can be applied at both global and regional scale. With increasing amounts of strong-motion records that are now available worldwide, observational data can provide a valuable resource to tackle this question. Using the global dataset of Allen and Wald (2009), we evaluate the ability of 11 GMPEs to predict ground-motion in different active shallow crustal regions worldwide. Adopting the approach of Scherbaum et al. (2009), we rank these GMPEs according to their likelihood of having generated the data. In particular, we estimate how strongly data support or reject the models with respect to the state of noninformativeness defined by a uniform weighting. Such rankings derived from this particular global dataset enable us to explore the potential of GMPEs to predict ground motions in their host region and also in other regions depending on the magnitude and distance considered. In the ranking process, we particularly focus on the influence of the distribution of the testing dataset compared with the GMPE's native dataset. One of the results of this study is that some nonindigenous models present a high degree of consistency with the data from a target region. Two models in particular demonstrated a strong power of geographically wide applicability in different geographic regions with respect to the testing dataset: the models of Akkar and Bommer (2010) and Chiou et al. (2010).
We introduce a theoretical framework for performing statistical hypothesis testing simultaneously over a fairly general, possibly uncountably infinite, set of null hypotheses. This extends the standard statistical setting for multiple hypotheses testing, which is restricted to a finite set. This work is motivated by numerous modern applications where the observed signal is modeled by a stochastic process over a continuum. As a measure of type I error, we extend the concept of false discovery rate (FDR) to this setting. The FDR is defined as the average ratio of the measure of two random sets, so that its study presents some challenge and is of some intrinsic mathematical interest. Our main result shows how to use the p-value process to control the FDR at a nominal level, either under arbitrary dependence of p-values, or under the assumption that the finite dimensional distributions of the p-value process have positive correlations of a specific type (weak PRDS). Both cases generalize existing results established in the finite setting, the latter one leading to a less conservative procedure. The interest of this approach is demonstrated in several non-parametric examples: testing the mean/signal in a Gaussian white noise model, testing the intensity of a Poisson process and testing the c.d.f. of i.i.d. random variables. Conceptually, an interesting feature of the setting advocated here is that it focuses directly on the intrinsic hypothesis space associated with a testing model on a random process, without referring to an arbitrary discretization.
We studied testate amoebae and possible correlated abiotic factors in soils of 31 mature forest ecosystems using an easily applicable and spatially explicit method. Simple counting on soil thin-sections with a light microscope resulted in amoeba densities comparable to previously reported values, i.e. 0.1 x 10(8) to 11.5 x 10(8) individuals m(-2) (upper 3 cm of soil). Soil moisture and soil acidity seem to be correlated with amoeba densities. At sites of moderate soil moisture regimes (SMR 2-7) we found higher densities of testate amoebae at pH < 4.5. At wetter sites (SMR >= 8) higher individual densities were recorded also at less acidic sites. The in situ description of amoebae, based on the analysis of a complete soil thin-section, showed a relatively uniform spatial micro-distribution throughout the organic and mineral soil horizons (no testate amoeba clusters). We discuss the pros and cons of the soil thin-section method and suggest it as an additional tool to improve knowledge of the spatial micro-distribution of testate amoebae.
Test-retest-reliability of metabolic and cardiovascular load during isokinetic strength testing
(2012)
Tensorial spacetime geometries carrying predictive, interpretable and quantizable matter dynamics
(2012)
Which tensor fields G on a smooth manifold M can serve as a spacetime structure? In the first part of this thesis, it is found that only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry predictive, interpretable and quantizable matter dynamics. The obvious dependence of this characterization of admissible tensorial spacetime geometries on specific matter is not a weakness, but rather presents an insight: it was Maxwell theory that justified Einstein to promote Lorentzian manifolds to the status of a spacetime geometry. Any matter that does not mimick the structure of Maxwell theory, will force us to choose another geometry on which the matter dynamics of interest are predictive, interpretable and quantizable. These three physical conditions on matter impose three corresponding algebraic conditions on the totally symmetric contravariant coefficient tensor field P that determines the principal symbol of the matter field equations in terms of the geometric tensor G: the tensor field P must be hyperbolic, time-orientable and energy-distinguishing. Remarkably, these physically necessary conditions on the geometry are mathematically already sufficient to realize all kinematical constructions familiar from Lorentzian geometry, for precisely the same structural reasons. This we were able to show employing a subtle interplay of convex analysis, the theory of partial differential equations and real algebraic geometry. In the second part of this thesis, we then explore general properties of any hyperbolic, time-orientable and energy-distinguishing tensorial geometry. Physically most important are the construction of freely falling non-rotating laboratories, the appearance of admissible modified dispersion relations to particular observers, and the identification of a mechanism that explains why massive particles that are faster than some massless particles can radiate off energy until they are slower than all massless particles in any hyperbolic, time-orientable and energy-distinguishing geometry. In the third part of the thesis, we explore how tensorial spacetime geometries fare when one wants to quantize particles and fields on them. This study is motivated, in part, in order to provide the tools to calculate the rate at which superluminal particles radiate off energy to become infraluminal, as explained above. Remarkably, it is again the three geometric conditions of hyperbolicity, time-orientability and energy-distinguishability that allow the quantization of general linear electrodynamics on an area metric spacetime and the quantization of massive point particles obeying any admissible dispersion relation. We explore the issue of field equations of all possible derivative order in rather systematic fashion, and prove a practically most useful theorem that determines Dirac algebras allowing the reduction of derivative orders. The final part of the thesis presents the sketch of a truly remarkable result that was obtained building on the work of the present thesis. Particularly based on the subtle duality maps between momenta and velocities in general tensorial spacetimes, it could be shown that gravitational dynamics for hyperbolic, time-orientable and energy distinguishable geometries need not be postulated, but the formidable physical problem of their construction can be reduced to a mere mathematical task: the solution of a system of homogeneous linear partial differential equations. This far-reaching physical result on modified gravity theories is a direct, but difficult to derive, outcome of the findings in the present thesis. Throughout the thesis, the abstract theory is illustrated through instructive examples.
Temporally changing drivers for late-Holocene vegetation changes on the northern Tibetan Plateau
(2012)
Fossil pollen records have been widely used as indicators of past changes in vegetation and variations in climate. The driving mechanisms behind these vegetation changes have, however, remained unclear. In order to evaluate vegetation changes that have occurred in the northern part of the Tibetan Plateau and the possible drivers behind these changes, we have applied a moving-window Redundancy Analysis (RDA) to high resolution (10-15 years) pollen and sedimentary data from Lake Kusai covering the last 3770 years. Our analyses reveal frequent fluctuations in the relative abundances of alpine steppe and alpine desert components. The sedimentary proxies (including total organic carbon content, total inorganic carbon content, and "end-member" indices from grain-size analyses) that explain statistically some of the changes in the pollen assemblage vary significantly with time, most probably reflecting multiple underlying driving processes. Climate appears to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, a gradual decrease in vegetation cover was identified after 1500 cal a BP, after which the vegetation appears to have been affected more by extreme events such as dust-storms or fluvial erosion than by general climatic trends. Furthermore, pollen spectra over the last 600 years are shown by Procrustes analysis to be statistically different from those recovered from older samples, which we attribute to increased human impact that resulted in unprecedented changes to the vegetation composition. Overall, changes in vegetation and climate on the northern part of the Tibetan Plateau appear to have roughly followed the evolution of the Asian Summer Monsoon. After taking into account the highly significant millennial (1512 years) periodicity revealed by time-series analysis, the regional vegetation and climate changes also show variations that appear to match variations in the mid-latitude westerlies.
Eye movements are a powerful tool to examine cognitive processes. However, in most paradigms little is known about the dynamics present in sequences of saccades and fixations. In particular, the control of fixation durations has been widely neglected in most tasks. As a notable exception, both spatial and temporal aspects of eye-movement control have been thoroughly investigated during reading. There, the scientific discourse was dominated by three controversies, (i), the role of oculomotor vs. cognitive processing on eye-movement control, (ii) the serial vs. parallel processing of words, and, (iii), the control of fixation durations. The main purpose of this thesis was to investigate eye movements in tasks that require sequences of fixations and saccades. While reading phenomena served as a starting point, we examined eye guidance in non-reading tasks with the aim to identify general principles of eye-movement control. In addition, the investigation of eye movements in non-reading tasks helped refine our knowledge about eye-movement control during reading. Our approach included the investigation of eye movements in non-reading experiments as well as the evaluation and development of computational models. I present three main results : First, oculomotor phenomena during reading can also be observed in non-reading tasks (Chapter 2 & 4). Oculomotor processes determine the fixation position within an object. The fixation position, in turn, modulates both the next saccade target and the current fixation duration. Second, predicitions of eye-movement models based on sequential attention shifts were falsified (Chapter 3). In fact, our results suggest that distributed processing of multiple objects forms the basis of eye-movement control. Third, fixation durations are under asymmetric control (Chapter 4). While increasing processing demands immediately prolong fixation durations, decreasing processing demands reduce fixation durations only with a temporal delay. We propose a computational model ICAT to account for asymmetric control. In this model, an autonomous timer initiates saccades after random time intervals independent of ongoing processing. However, processing demands that are higher than expected inhibit the execution of the next saccade and, thereby, prolong the current fixation. On the other hand, lower processing demands will not affect the duration before the next saccade is executed. Since the autonomous timer adjusts to expected processing demands from fixation to fixation, a decrease in processing demands may lead to a temporally delayed reduction of fixation durations. In an extended version of ICAT, we evaluated its performance while simulating both temporal and spatial aspects of eye-movement control. The eye-movement phenomena investigated in this thesis have now been observed in a number of different tasks, which suggests that they represent general principles of eye guidance. I propose that distributed processing of the visual input forms the basis of eye-movement control, while fixation durations are controlled by the principles outlined in ICAT. In addition, oculomotor control contributes considerably to the variability observed in eye movements. Interpretations for the relation between eye movements and cognition strongly benefit from a precise understanding of this interplay.
1. Poikilothermic animals incorporate more polyunsaturated fatty acids (PUFAs) into their cellular membranes as temperature declines, suggesting an increased sensitivity to PUFA limitation in cool conditions. To test this we raised Daphnia magna at different temperatures and investigated the effect of varying dietary PUFA on life history parameters (i.e. growth, reproduction) and the PUFA composition of body tissue and eggs.
2. Upon a PUFA-rich diet (Cryptomonas sp.) females showed higher concentrations of several omega 3 PUFAs in their body tissue at 15 degrees C than at 20 degrees C and 25 degrees C, indicating a greater structural requirement for omega 3 PUFAs at low temperature. Their eggs had an equal but higher concentration of omega 3 PUFAs than their body tissue.
3. In a life history experiment at 15 and 20 degrees C we supplemented a diet of a PUFA-free cyanobacterium with the omega 3 PUFA eicosapentaenoic acid (EPA). The growth of D. magna was more strongly EPA limited at low temperature. A greater requirement for structural EPA at 15 degrees C was indicated by a steeper increase in somatic EPA content with dietary EPA compared to 20 degrees C.
4. At 20 degrees C the development of eggs to successful hatching was high when EPA was supplied to the mothers. At 15 degrees C the hatching success was generally poor, despite of a higher maternal provision of EPA to eggs, compared to that at 20 degrees C, suggesting that EPA alone was insufficient for proper neonatal development at the low temperature. The growth of offspring from mothers raised at 20 degrees C without EPA supplementation was very low, indicating that the negative effects of EPA deficiency can be carried on to the next generation.
5. The fatty acid composition of Daphnia sp. in published field studies shows increasing proportions of saturated fatty acids with increasing environmental temperature, whereas omega 3 PUFAs and EPA show no clear pattern, suggesting that variations in dietary PUFA may mask temperature-dependent adjustments in omega 3 PUFA concentrations of cladocerans in nature.
To identify copper homeostasis genes in Rhodobacter capsulatus, we performed random transposon Tn5 mutagenesis. Screening of more than 10,000 Tn5 mutants identified tellurite resistance gene trgB as a so far unrecognized major copper tolerance determinant. The trgB gene is flanked by tellurite resistance gene trgA and cysteine synthase gene cysK2. While growth of trgA mutants was only moderately restricted by tellurite, trgB and cysK2 mutants were severely affected by tellurite, which implies that viability under tellurite stress requires increased cysteine levels. Mutational analyses revealed that trgB was the only gene in this chromosomal region conferring cross-tolerance towards copper. Expression of the monocistronic trgB gene required promoter elements overlapping the trgA coding region as shown by nested deletions. Neither copper nor tellurite affected trgB transcription as demonstrated by reverse transcriptase PCR and trgB-lacZ fusions. Addition of tellurite or copper gave rise to increased cellular tellurium and copper concentrations, respectively, as determined by inductively coupled plasma-optical emission spectroscopy. By contrast, cellular iron concentrations remained fairly constant irrespective of tellurite or copper addition. This is the first study demonstrating a direct link between copper and tellurite response in bacteria.
We have undertaken structural, geomorphological, and morphometric analyses to investigate the role of tectonism and climate in the landscape evolution in the upper Spiti valley, NW Himalayas. Geomorphometric analyses coupled with field investigations reveal active tectonic deformation in the Spiti region. The calculated geomorphic indices (steepness, concavity and Hack) demonstrate uplift/subsidence along the Kaurik-Chango fault, whereas transverse topographic index (T-index) reveals basin tilting associated with active faulting near Hansa and Lingti valley. Investigation of well-dated Mane palaeolake sediments also provides evidence of regional tectonic instability. Four episodes (ca. 7.8, 7.4, 6.5 and 6.1 cal ka) of neotectonic activity have been identified during the period of the lake's existence. We have also compiled data on the regional climate variability and compared it with the age of the Mane palaeo-landslide. Our results indicate that the landslide occurred towards the end of the early Holocene intensified monsoon phase and is located near an active fault. Our data on regional tectonic instability and the coincidences of modern and palaeo-landslides with zones of active deformation suggest that tectonism is an important factor governing landscape stability in the Spiti region.