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The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from −31 to 99% for dry weight and from −58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross.
The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from −31 to 99% for dry weight and from −58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross.
Prediction of hybrid biomass in Arabidopsis thaliana by selected parental SNP and metabolic markers
(2009)
A recombinant inbred line (RIL) population, derived from two Arabidopsis thaliana accessions, and the corresponding testcrosses with these two original accessions were used for the development and validation of machine learning models to predict the biomass of hybrids. Genetic and metabolic information of the RILs served as predictors. Feature selection reduced the number of variables (genetic and metabolic markers) in the models by more than 80% without impairing the predictive power. Thus, potential biomarkers have been revealed. Metabolites were shown to bear information on inherited macroscopic phenotypes. This proof of concept could be interesting for breeders. The example population exhibits substantial mid-parent biomass heterosis. The results of feature selection could therefore be used to shed light on the origin of heterosis. In this respect, mainly dominance effects were detected.
Prediction of hybrid biomass in Arabidopsis thaliana by selected parental SNP and metabolic markers
(2009)
A recombinant inbred line (RIL) population, derived from two Arabidopsis thaliana accessions, and the corresponding testcrosses with these two original accessions were used for the development and validation of machine learning models to predict the biomass of hybrids. Genetic and metabolic information of the RILs served as predictors. Feature selection reduced the number of variables (genetic and metabolic markers) in the models by more than 80% without impairing the predictive power. Thus, potential biomarkers have been revealed. Metabolites were shown to bear information on inherited macroscopic phenotypes. This proof of concept could be interesting for breeders. The example population exhibits substantial mid-parent biomass heterosis. The results of feature selection could therefore be used to shed light on the origin of heterosis. In this respect, mainly dominance effects were detected.
An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential. A catalytic oxidation current was detected in the presence of sulfite at the modified gold electrode, polarized at +0.1 V ( vs. Ag/AgCl 1 M KCl). The stability of the biosensor performance was characterized and optimized. A 17-bilayer electrode has a linear range between 1 and 60 mu M sulfite with a sensitivity of 2.19 mA M-1 sulfite and a response time of 2 min. The electrode retained a stable response for 3 days with a serial reproducibility of 3.8% and lost 20% of sensitivity after 5 days of operation. It is possible to store the sensor in a dry state for more than 2 months. The multilayer electrode was used for determination of sulfite in unspiked and spiked samples of red and white wine. The recovery and the specificity of the signals were evaluated for each sample.
We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852-1973) and Hoya Rincn de Parangueo (AD 1839-1943). These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutin (1943/1944) and (210)Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in (13)C and (18)O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Nio events, and positive SST anomalies. Based on our data, droughts (3-7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincn. The proxy data indicate a faster response to increased evaporation for Rincn, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.
The satellite era brings new challenges in the development and the implementation of potential field models. Major aspects are, therefore, the exploitation of existing space- and ground-based gravity and magnetic data for the long-term. Moreover, a continuous and near real-time global monitoring of the Earth system, allows for a consistent integration and assimilation of these data into complex models of the Earth’s gravity and magnetic fields, which have to consider the constantly increasing amount of available data. In this paper we propose how to speed up the computation of the normal equation in potential filed modeling by using local multi-polar approximations of the modeling functions. The basic idea is to take advantage of the rather smooth behavior of the internal fields at the satellite altitude and to replace the full available gravity or magnetic data by a collection of local moments. We also investigate what are the optimal values for the free parameters of our method. Results from numerical experiments with spherical harmonic models based on both scalar gravity potential and magnetic vector data are presented and discussed. The new developed method clearly shows that very large datasets can be used in potential field modeling in a fast and more economic manner.
Special p-forms are forms which have components fµ1…µp equal to +1, -1 or 0 in some orthonormal basis. A p-form ϕ ∈ pRd is called democratic if the set of nonzero components {ϕμ1...μp} is symmetric under the transitive action of a subgroup of O(d,Z) on the indices {1, . . . , d}. Knowledge of these symmetry groups allows us to define mappings of special democratic p-forms in d dimensions to special democratic P-forms in D dimensions for successively higher P = p and D = d. In particular, we display a remarkable nested structure of special forms including a U(3)-invariant 2-form in six dimensions, a G2-invariant 3-form in seven dimensions, a Spin(7)-invariant 4-form in eight dimensions and a special democratic 6-form O in ten dimensions. The latter has the remarkable property that its contraction with one of five distinct bivectors, yields, in the orthogonal eight dimensions, the Spin(7)-invariant 4-form. We discuss various properties of this ten dimensional form.
Communicative style
(2009)
The talk will focus on a few central problems in Game Studies: The question of where to locate game meaning, game defintions and how to avoid them, and the conundrum of games vs stories. In all these problems, the choice of ludic perspective (e.g. are games artifacts, systems or activities?) limits our ability to discuss games across disciplinary boundaries. What is needed is a metaperspective that will offer the field a chance to move on.
We used single-molecule FRET in combination with other biophysical methods and molecular simulations to investigate the effect of temperature on the dimensions of unfolded proteins. With singlemolecule FRET, this question can be addressed even under nearnative conditions, where most molecules are folded, allowing us to probe a wide range of denaturant concentrations and temperatures. We find a compaction of the unfolded state of a small cold shock protein with increasing temperature in both the presence and the absence of denaturant, with good agreement between the results from single-molecule FRET and dynamic light scattering. Although dissociation of denaturant from the polypeptide chain with increasing temperature accounts for part of the compaction, the results indicate an important role for additional temperaturedependent interactions within the unfolded chain. The observation of a collapse of a similar extent in the extremely hydrophilic, intrinsically disordered protein prothymosin suggests that the hydrophobic effect is not the sole source of the underlying interactions. Circular dichroism spectroscopy and replica exchange molecular dynamics simulations in explicit water show changes in secondary structure content with increasing temperature and suggest a contribution of intramolecular hydrogen bonding to unfolded state collapse.
Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Cell cycle-dependent localization of novel centrosomal and centromeric proteins in Dictyostelium
(2009)
The investigated HP/LT metasedimentary units of the Valaisan and adjacent European domains occupy a key position in the Alpine belt for understanding the transition from early subduction-related HP/LT metamorphism to collision-related Barrovian overprint and the evolution of mountain belts in general. The timing of high-pressure metamorphism, subsequent retrogression and following Barrow-type overprint was studied by Ar-40/Ar-39 dating of biotite and several white mica generations that are well characterized in terms of mineral chemistry, texture and associated mineral assemblages. Four distinct age populations of white mica record peak pressure conditions (42-40 Ma) and several stages of subsequent retrograde metamorphic evolution (36-25 Ma). Biotite isotopic analyses yield consistent apparent ages that cluster around 18-16 Ma for the Barrow-type thermal overprint. The recorded isotopic data reveal a significant time gap in the order of some 20 Ma between subduction-related HP/LT metamorphism and collision-related Barrovian overprint, supporting the notion of a polymetamorphic evolution associated with a bimodal P-T path.
With the advancement of computational systems and the development of model integration concepts, complexity of environmental model systems increased. In contrast to that, theory and knowledge about>environmental systems as well as the capability for environmental systems analyses remained, to a large extent, unchanged. As a consequence, model conceptualization, data gathering, and validation, have faced new challenges that hardly can be tackled by modellers alone. In this discourse-like review, we argue that modelling with reliable simulations of human-environmental interactions necessitate linking modelling and simulation research much stronger to science fields such as landscape ecology, community ecology, eco-hydrology, etc. It thus becomes more and more important to identify the adequate degree of complexity in environmental models (which is not only a technical or methodological question), to ensure data availability, and to test model performance. Even equally important, providing problem specific answers to environmental problems using simulation tools requires addressing end-user and stakeholder requirements during early stages of problem development. In doing so, we avoid modelling and simulation as an end of its own.
Carrier transport and recombination have been studied in single component layers and blends of the soluble PPV- derivative poly[2,5-dimethoxy-1,4-phenylenevinylene-2-methoxy-5-(2-ethyl-hexyloxy)- 1,4-phenylenevinylene] (M3EH-PPV) and the small molecule acceptor 4,7-bis(2-(1-hexyl-4,5-dicyanoimidazole-2-yl)vinyl) benzo[c][1,2,5]-thiadiazole (HV-BT). Measurements on single carrier devices show significantly smaller electron mobility in the blend compared to the pure HV- BT layer, which is suggestive of the formation of isolated clusters of the acceptor in a continuous polymer matrix. The significant change in fill factor (FF) with increasing illumination intensity is consistently explained by a model taking into account bimolecular recombination and space charge effects. The decay of the carrier density after photoexcitation has been studied by performing photo-CELIV measurements on pure and blend layers. It is found that the decay at long delay times follows a power-law dependence, which is, however, not consistent with a Langevin-type bimolecular recombination of free charges. A good description of the data is obtained by assuming trimolecular recombination to govern the charge carrier dynamics in these systems.
The EEG is one of the most commonly used tools in brain research. Though of high relevance in research, the data obtained is very noisy and nonstationary. In the present article we investigate the applicability of a nonlinear data analysis method, the recurrence quantification analysis (RQA), to Such data. The method solely rests on the natural property of recurrence which is a phenomenon inherent to complex systems, such as the brain. We show that this method is indeed suitable for the analysis of EEG data and that it might improve contemporary EEG analysis.
Accretionary orogens are considered major sites of formation of juvenile continental crust. In the central and southern Andes this is contradicted by two observations: siliciclastic fills of Paleozoic basins in the central Andean segment of the accretionary Terra Australis Orogen consist almost exclusively of shales and mature sandstones; and magmatic rocks connected to the Famatinian (Ordovician) and Late Paleozoic magmatic arcs are predominantly felsic and characterized by significant crustal contamination and strongly unradiogenic Nd isotope compositions. Evidence of juvenile crustal additions is scarce. We present laser ablation (LA)-ICPMS U-Pb ages and LA-MC-ICPMS Hf isotope data of detrital zircons from seven Devonian to Permian turbidite sandstones incorporated into a Late Paleozoic accretionary wedge at the western margin of Gondwana in northern Chile. The combination with Nd whole-rock isotope data permits us to trace the evolution of the South American continental crust through several Proterozoic and Paleozoic orogenic cycles. The analyzed detrital zircon spectra reflect all Proterozoic orogenic cycles representing the step-wise evolution of the accretionary SW Amazonia Orogenic System between 2.0 and 0.9 Ga, followed by the Terra Australis Orogen between 0.9 and 0.25 Ga. The zircon populations are characterized by two prominent maxima reflecting input from Sunsas (Grenville) age magmatic rocks (1.2-0.9 Ga) and from the Ordovician to Silurian Famatinian magmatic arc (0.52-0.42 Ga). Grains of Devonian age are scarce or absent from the analyzed zircon populations. The Hf isotopic compositions of selected dated zircons at the time of their crystallization (epsilon Hf-(T); T = 3.3-0.25 Ga) vary between -18 and +11. All sandstones have a significant juvenile component; between 20 and 50% of the zircons from each sedimentary rock have positive epsilon Hf-(T) and can be considered juvenile. The majority of the juvenile grains have Hf-depleted mantle model ages (Hf T-DM) between 1.55 and 0.8 Ga. the time of the Rondonia-San Ignacio and Sunsas orogenic events on the Amazonia craton. The corresponding whole-rock epsilon Nd-(T) values fot these same rocks are between -8 and -3 indicating a mixture of older evolved and juvenile sources. Nd-depleted mantle model ages (Nd T-DM*) are between 1.5 and 1.2 Ga and coincide broadly with the zircon Hf model ages. Our data indicate that the Paleo- and Mesoproterozoic SW Amazonia Orogenic System, and the subsequent Neoproterozoic and Paleozoic Terra Australis Orogen in the region of the central and southern Andes, developed following two markedly different patterns of accretionary orogenic crustal evolution. The SW Amazonia Orogenic System developed by southwestward growth over approximately 1.1 Ga through a combination of accretion of juvenile material and crustal recycling typical of the extensional or retreating mode of accretionary orogens. In contrast, the central Andean segment of the Terra Australis Orogen evolved from 0.9 to 0.25 Ga in the compressional or advancing mode in a relatively fixed position without the accretion of oceanic crustal units or large scale input of juvenile material to the orogenic crust. Here, recycling mainly of Mesoproterozoic continental crust has been the dominant process of crustal evolution. (C) 2009 Elsevier B.V. All rights reserved.
Aims. Sunspot distribution in the northern and southern solar hemispheres exibit striking synchronous behaviour on the scale of a Schwabe cycle. However, sometimes the bilateral symmetry of the Butterfly diagram relative to the solar equatorial plane breaks down. The investigation of this phenomenon is important to explaining the almost-periodic behaviour of solar cycles. Methods. We use cross-recurrence plots for the study of the time-varying phase asymmetry of the northern and southern hemisphere and compare our results with the latitudinal distribution of the sunspots. Results. We observe a long-term persistence of phase leading in one of the hemispheres, which lasts almost 4 solar cycles and probably corresponds to the Gleissberg cycle. Long-term variations in the hemispheric-leading do not demonstrate clear periodicity but are strongly anti-correlated with the long-term variations in the magnetic equator.
The seismicity of the Kenya rift is characterized by high-frequency low-magnitude events concentrated along the rift axis. Its seismic character is typical for magmatically active continental rifts, where igneous material at a shallow depth causes extensive grid faulting and geothermal activity. Thermal overprinting and dike intrusion prohibit the buildup of large elastic strains, therefore prohibiting the generation of large-magnitude earthquakes. On 6 January 1928, the M-S 6.9 Subukia earthquake occurred on the Laikipia-Marmanet fault, the eastern rift-bounding structure of the central Kenya rift. It is the largest instrumentally recorded seismic event in the Kenya rift, standing in contrast to the current model of the rift's seismic character in which large earthquakes are not anticipated. Furthermore, the proximity of the ruptured fault and the rift axis is intriguing: The rift-bounding structure that ruptured in 1928 remains seismically active, capable of generating large-magnitude earthquakes, even though thermally weakened crust and better oriented structures are present along the rift axis nearby, prohibiting any significant buildup of elastic strain. We excavated the surface rupture of the 1928 Subukia earthquake to find evidence for preceding ground-rupturing earthquakes. We also made a total station survey of the site topography and mapped the site geology. We show that the Laikipia-Marmanet fault was repeatedly activated during the late Quaternary. We found evidence for six ground-rupturing earthquakes, including the 1928 earthquake. The topographic survey around the trench site revealed a degraded fault scarp of approximate to 7.5 m in height, offsetting a small debris slide. Using scarp-diffusion modeling, we estimated an uplift rate of U = 0.09-0.15 mm/yr, constraining the scarp age to 50-85 ka. Assuming an average fault dip of 55 degrees-75 degrees, the preferred uplift rate (0.15 mm/yr) accommodates approximately 10%-20% of the recent rate of extension (0.5 mm/yr) across the Kenya rift.
Objective: Questionnaires are often applied in sports psychology to measure a person's trait or state. However, the extent to which the questionnaire captures differences because of trait or state influences is often unclear. The latent state-trait (LST) theory offers the opportunity to separate both variance sources. This separation allows estimating specific reliability coefficients. Design: The present paper gives a theoretical introduction to LST and its basic ideas. Using a real data set with N = 156 athletes we exemplify the steps necessary to derive the LST coefficients. All athletes filled out a comprehensive inventory assessing competitive anxiety on two occasions. Method: The data are analysed with structural equation models based on LST principles. Results: The results confirm the questionnaire's trait saturation. Conclusion: Finally, results are discussed in light of practical and theoretical implications.
We use a data set of 35 surface pollen samples from lake sediments, moss polsters and top soils on the north- eastern Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The surface pollen transect spanned four vegetation zones--alpine meadow, steppe, steppe desert and desert-- under different climatic/elevational conditions. Relative representation (R (rel)) values and Principal Components Analysis (PCA) were used to determine the relationships between modern pollen and vegetation and regional climate gradients. The results show that the main vegetation zones along the regional and elevational transects can be distinguished by their modern pollen spectra. Relative to Poaceae, a high representation of Artemisia, Nitraria and Chenopodiaceae was found, while Cyperaceae and Gentiana showed values in the middle range, and Ranunculaceae, Asteraceae, Ephedra and Fabaceae had low relative representation values. PCA results indicate a high correlation between the biogeoclimatic zones and annual precipitation and annual temperature and July temperature. The Artemisia/ Chenopodiaceae ratio and the Artemisia/Cyperaceae ratio are useful tools for qualitative and semi-quantitative palaeoenvironmental reconstruction on the north-eastern Tibetan Plateau. Surface lake sediments are found to have different palynomorph spectra from moss cushion and soil samples, reflecting the larger pollen source area in the contemporary vegetation for lakes.
Clustered codons that pair to low-abundance tRNA isoacceptors can form slow-translating regions in the mRNA and cause transient ribosomal arrest. We report that folding efficiency of the Escherichia coli multidomain protein Sufl can be severely perturbed by alterations in ribosome-mediated translational attenuation. Such alterations were achieved by global acceleration of the translation rate with tRNA excess in vitro or by synonymous substitutions to codons with highly abundant tRNAs both in vitro and in vivo. Conversely, the global slow-down of the translation rate modulated by low temperature suppresses the deleterious effect of the altered translational attenuation pattern. We propose that local discontinuous translation temporally separates the translation of segments of the peptide chain and actively coordinates their co-translational folding.
Laser-driven plasma sources of femtosecond hard X-ray pulses have found widespread application in ultrafast X- ray diffraction. The recent development of plasma sources working at kilohertz repetition rates has allowed for diffraction experiments with strongly improved sensitivity, now revealing subtle fully reversible changes of the geometry of crystal lattices. We provide a brief review of this development and present a novel plasma source with an optimized mechanical and optical design, providing a high flux of several 10(10) photons/s at the Cu-K alpha energy of 8.04 keV and a pulse duration of a parts per thousand currency sign300 fs. First experiments, including the generation of Debye-Scherrer diffraction patterns from Si powder, demonstrate the high performance of this source.
Sensory information entering the nervous system follows independent paths of processing such that specific features are individually detected. However, sensory perception, awareness, and cognition emerge from the combination of information. Here we have analyzed the corticocortical network of the cat, looking for the anatomical substrate which permits the simultaneous segregation and integration of information in the brain. We find that cortical communications are mainly governed by three topological factors of the underlying network: (i) a large density of connections, (ii) segregation of cortical areas into clusters, and (iii) the presence of highly connected hubs aiding the multisensory processing and integration. Statistical analysis of the shortest paths reveals that, while information is highly accessible to all cortical areas, the complexity of cortical information processing may arise from the rich and intricate alternative paths in which areas can influence each other.
Upper Thanetian microbialite-coral mounds from the Adriatic Carbonate Platform (SW Slovenia) are described herein for the first time, representing an important case study of extensively microbially-cemented boundstones in the Early Paleogene. The mounds are constructed primarily by microbialites associated to small-sized coral colonies, forming metric bioconstructions in a mid-ramp setting. Detailed macroscopic and microscopic studies show that microbes are the major framework builders, playing a prominent role in the stabilization and growth of the mounds, with corals being the second most important component. Microbial carbonates represent up to 70% of the mounds, forming centimetric-thick crusts alternating with coral colonies. The microbial nature of the crusts is demonstrated by their growth form and internal microfabrics, showing accretionary, binding, and encrusting growth fabrics, often with gravity-defying geometries. Thin sections and polished slabs reveal a broad range of mesofabrics, with dense, structureless micrite (leiolite), laminated crusts (stromatolites), and clotted micritic masses (thrombolites). A first layer of micro- encrusters, including leiolites and thrombolites, occurs in cryptic habitats, whereas discontinuous stromatolites encrust the upper surface of corals. A second encrustation, the major mound construction phase, follows and is dominated by thrombolites, encrusting corals and other micro-encrusters. This sequence represents the basic constructional unit horizontally and vertically interlocked, in an irregular pattern, to form the mounds. The processes, which favored the deposition of these microbial carbonates, were mainly related to in situ precipitation, with minor evidences for grain agglutination and trapping processes. Scleractinian corals comprise moderately diversified community of small (centimetric) colonial, massive, platy encrusting, and branching forms. Coral colonies are distributed uniformly throughout the mounds without developing any ecological zonation. These features indicate that coral development remained at the pioneer stage throughout the mound growth. The spatial relationships between corals and microbialites, as well as the characteristics of microbial crusts and coral colonies, indicate a strong ecological competition between corals and microbes. A model for the evolution of the trophic structures during the mound growth is proposed, with changes in the paleoecology of the main bioconstructors triggered by frequent environmental perturbations. Turbidity and nutrient pressure, interpreted here as related to frequent recurrences of wet phases during the warm, humid climate of the Uppermost Thanetian, might have promoted temporary dominance of microbes over corals, causing rapid environmentally- driven "phase shifts" in the dominant biota.
Closed and re-opened for business: C-2 branched carbohydrates 1 cyclize under conditions of decarboxylation to the hitherto unknown carbohydrate 1,2-lactones 2 in high yields. The gluco isomer can be opened at the anomeric position with various nuceophiles in the presence of Sc(OTf)3, which allows the stereoselective synthesis of 1-functionalized glucose derivatives 3. Thus, 1,2-bis-C-branched saccharides become available in only a few steps starting from glycals.
Entanglement combing
(2009)
We show that all multipartite pure states can, under local operations, be transformed into bipartite pairwise entangled states in a "lossless fashion": An arbitrary distinguished party will keep pairwise entanglement with all other parties after the asymptotic protocol-decorrelating all other parties from each other-in a way that the degree of entanglement of this party with respect to the rest will remain entirely unchanged. The set of possible entanglement distributions of bipartite pairs is also classified. Finally, we point out several applications of this protocol as a useful primitive in quantum information theory.
The response of scale-free networks with community structure to external stimuli is studied. By disturbing some nodes with different strategies, it is shown that the robustness of this kind of network can be enhanced due to the existence of communities in the networks. Some of the response patterns are found to coincide with topological communities. We show that such phenomena also occur in the cat brain network which is an example of a scale-free like network with community structure. Our results provide insights into the relationship between network topology and the functional organization in complex networks from another viewpoint.
Grouping patterns within the genus Tragelaphus suggest that species inhabiting open areas tend to live in larger groups, while species preferring dense habitats live solitarily or in small family groups. We asked if similar variation would be concealed in the within-species variation of bushbuck (Tragelaphus scriptus). Recent molecular phylogeographic analyses revealed several locally adapted forms of bushbuck in different ecoregions on the African continent. We compared group sizes of south-eastern bushbuck (Tragelaphus sylvaticus) among six different populations ("ecotypes"). To date, most data on the social organization of bushbuck have been collected from only one population in Queen Elizabeth National Park (QENP) in Uganda. This particular population, however, inhabits an unusual-comparatively open-habitat type, while bushbuck otherwise inhabit dense habitats, leaving doubt whether data collected in QENP are representative of the entire species. We, therefore, compared grouping patterns between ecotypes inhabiting rather open habitats (e.g., dianae and haywoodi) and ecotypes occupying rather dense habitats (e.g., massaicus and ornatus). In bachelor groups and in all-female (spinster) groups, single sightings were the most frequent "group type" in all populations examined. We detected no significant difference among ecotypes in relative frequencies of group size categories in the case of bachelor groups. Spinster group sizes were slightly (albeit significantly) smaller in QENP than in all other areas. Moreover, a comparison of two areas inside (low human pursuit) and outside Lake Mburo National Park (high hunting pressure) in Uganda revealed no significant difference in grouping patterns in response to human pursuit (as reported for impala [Aepyceros melampus] inhabiting the same area). Altogether, our results suggest that group sizes in bushbuck are not dependent on the habitat type they inhabit; neither does human nuisance have an impact on grouping patterns. Hence, an "almost solitary" lifestyle appears to be a characteristic of the entire taxon.
It has been suggested that all species of spiral-horned antelopes (Tragelaphini) lack territoriality. Furthermore, some authors suggested that bushbuck (Tragelpahus scriptus) males form dominance hierarchies. In this study, we investigated the dominance relationships in two groups of free-ranging bushbuck males in Queen Elizabeth National Park, Uganda. Adult males dominated young-adult bachelors and subadult males, but no distinct dominance relationships were found among adult males. Landau's index of linearity revealed no linear dominance hierarchy in the study populations. Our results support the idea that adult males are territorial, and overt aggression is directed almost exclusively towards bachelors that challenge territory holders.
The yellowhammer Emberiza citrinella is a common European bird that sings in dialects that for decades have been distinguished by the existence of one single element (called a "specific''). In this study we looked into other possibilities for dialect discrimination, measuring 24 different variables. For the first time, multivariate statistics were used to discriminate dialect in yellowhammer song. Two similar dialects (XlB and XsB) that are not clearly defined in the literature were studied. Statistics incorporated (1) all variables, ( 2) no variables of "specific'' elements, and (3) no variables under the influence of these "specific'' variables. Multivariate statistics support dialect discrimination by ear and confirmed that only one element in yellowhammer song characterises dialect. In addition, we looked for local differences within two dialects and found that one local observation area showed a higher separation than the other sites (Meck1). However, as yet there is insufficient evidence for the existence of a new subdialect.
Femtosecond x-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO3/PbZr0.2Ti0.8O3 (SRO/ PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1 ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO3 (STO) SL.
Resynthesis of handshake specifications obtained e. g. from BALSA or TANGRAM with speed-independent logic synthesis from STGs is a promising approach. To deal with state-space explosion, we suggested STG decomposition; a problem is that decomposition can lead to irreducible CSC conflicts. Here, we present a new approach to solve such conflicts by introducing internal communication between the components. We give some first, very encouraging results for very large STGs concerning synthesis time and circuit area.
Tuning the thickness of polymer brushes grafted from nonlinearly growing multilayer assemblies
(2009)
A new versatile method for tuning the thickness of surface-tethered polymer brushes is introduced. It is based on the combination of polyelectrolyte multilayer deposition and surface-initiated atom transfer radical polymerization. To control the thickness of the brushes, the nonlinear growth of certain polyelectrolyte multilayer systems is exploited. The method is demonstrated to work with different polyelectrolytes and different monomers. The relevance for applications is demonstrated by cell adhesion experiments oil grafted thermoresponsive polymer layers with varying thickness.
The Madre de Dios Metamorphic Complex (MDMC) in southern Chile is a fossil frontal accretionary prism, which is mainly composed of metapsammopelitic rocks, intercalations of oceanic rocks (greenstone and metachert) and platform carbonate. We concentrated on the metabasite to decipher the metamorphic evolution. This rock type contains assemblages of the pumpellyite-actinolite facies: pumpellyite +/- actinolite-chlorite +/- grandite +/- phengite +/- epidote-albite- quartz-titanite +/- K-feldspar +/- calcite. The metamorphic phases mainly grew by prograde hydration reactions during various episodes of restricted fluid influx. Fundamental phase relations of the pumpellyite-actinolite facies and adjacent facies were reproduced by pseudosections calculated for the system K2O-Na2O-CaO-FeO-O-2-MgO-Al2O3-TiO2-SiO2-H2O- CO2 at 200-400 degrees C and 1-9 kbar. The calculated stability fields of the metamorphic assemblages as realized in the MDMC metabasite indicate highest metamorphic conditions restricted to 290-310 degrees C, 4-6 kbar for the MDMC, presumably as a result of the main fluid influx at these conditions. Nevertheless, earlier local equilibria are still preserved as a result of strongly kinetically controlled mineral reactions and a lack of recrystallization and compositional homogenization at thin-section scale. Hence, thermodynamic calculations of local multivariant mineral equilibria using the entire compositional variation of minerals in the MDMC show that the prograde PT path evolved from 4 +/- 1 kbar, 200-220 degrees C to 5 +/- 1 kbar, 290-330 degrees C. The prograde PT path reflects nearly horizontal particle paths after reaching the maximum depth typical for frontal accretionary prisms. Long residence at maximum depth resulted in thermal re-equilibration. Ar-40/Ar-39 spot ages were measured by in situ UV laser ablation of local phengite concentrations in a deformed metapelite at 233 center dot 2 +/- 1 center dot 8 Ma and in an undeformed metabasite at 200 center dot 8 +/- 2 center dot 4 Ma. Whereas the first age represents an age of accretion, the latter age can be attributed to mineral growth either during a younger stage of accretion or during a retrograde stage. Ar-40/Ar-39 isotopic analyses of two further metabasite samples reflect a prominent resetting of ages at 152 center dot 0 +/- 2 center dot 2 Ma and white mica growth during external fluid access triggered by either a local intrusion or a late Jurassic extensional episode.
The phototrophic purple bacterium Rhodobacter capsulatus encodes two transcriptional regulators, MopA and MopB, with partially overlapping and specific functions in molybdate-dependent gene regulation. Both MopA and MopB consist of an N-terminal DNA-binding helix-turn-helix domain and a C-terminal molybdate-binding di-MOP domain. They formed homodimers as apo-proteins and in the molybdate-bound state as shown by yeast two-hybrid (Y2H) studies, glutaraldehyde cross-linking, gel filtration chromatography, and copurification experiments. Y2H studies suggested that both the DNA- binding and the molybdate-binding domains contribute to dimer formation. Analysis of molybdate binding to MopA and MopB revealed a binding stoichiometry of four molybdate oxyanions per homodimer. Specific interaction partners of MopA and MopB were the molybdate transporter ATPase ModC and the molbindin-like Mop protein, respectively. Like other molbindins, the R. capsulatus Mop protein formed hexamers, which were stabilized by binding of six molybdate oxyanions per hexamer. Heteromer formation of MopA and MopB was shown by Y2H studies and copurification experiments. Reporter gene activity of a strictly MopA-dependent mop-lacZ fusion in mutant strains defective for either mopA, mopB, or both suggested that MopB negatively modulates expression of the mop promoter. We propose that depletion of the active MopA homodimer pool by formation of MopA-MopB heteromers might represent a fine-tuning mechanism controlling mop gene expression.
BACKGROUND: Recent studies indicate that the bioavailability of anthocyanins is extremely low. One of the possible reasons could be their binding to proteins. Therefore, the binding affinity of cyanidin-3-glucoside (Cy3glc) to HSA and alpha-amylase was investigated by the quenching of protein tryptophan fluorescence. From data obtained, the binding constants and the free Gibbs energy were calculated. The changes in conformation of the proteins tested were studied with circular dichroism and the influence of binding on alpha-amylase activity determined. RESULTS: Cy3glc quenched the tryptophan fluorescence and upon ligand binding a change in protein structure was observed related to the corresponding decrease in the et-amylase activity. The association constants of 25 to 77 x 10(3) L mol(-1) were calculated for different proteins, indicating weak interactions of non-covalent nature. Competitive binding with HSA in the presence of 8-anilino-1-naphthalene sulfonic acid suggest involvement of hydrophobic interactions, in the case of HSA the possible site being subdomain IIA. CONCLUSION: The strongest affinity of Cy3glc for HSA being at pH 7 underlines its potential in transport and distribution of the phenolic compounds in organisms. An influence on salivary amylase activity is possible when drinking berry juices with high anthocyanins content.
Energy balance is maintained by controlling both energy intake and energy expenditure. Thyroid hormones play a crucial role in regulating energy expenditure. Their levels are adjusted by a tight feed back-control led regulation of thyroid hormone production/incretion and by their hepatic metabolism. Thyroid hormone degradation has previously been shown to be enhanced by treatment with phenobarbital or other antiepileptic drugs due to a CAR-dependent induction of phase 11 enzymes of xenobiotic metabolism. We have recently shown, that PPAR alpha agonists synergize with phenobarbital to induce another prototypical CAR target gene, CYP2B1. Therefore, it was tested whether a PPAR alpha agonist could enhance the phenobarbital-dependent acceleration of thyroid hormone elimination. In primary cultures of rat hepatocytes the apparent half-life of T3 was reduced after induction with a combination of phenobarbital and the PPARa agonist WY14643 to a larger extent than after induction with either Compound alone. The synergistic reduction of the half-life could be attributed to a synergistic induction of CAR and the CAR target genes that code for enzymes and transporters involved in the hepatic elimination of T3, such as OATP1A1, OATP1A3, UGT1A3 and UCT1A10. The PPAR alpha-dependent CAR induction and the subsequent induction of T3-eliminating enzymes might be of physiological significance for the fasting- incluced reduction in energy expenditure by fatty acids as natural PPARa ligands. The synergism of the PPAR alpha agonist WY14643 and phenobarbital in inducing thyroid hormone breakdown might serve as a paradigm for the synergistic disruption of endocrine control by other combinations of xenobiotics.
The incidence of cardiovascular diseases increases with the growth of the human population and an aging society, leading to very high expenses in the public health system. Therefore, it is challenging to develop sophisticated methods in order to improve medical diagnostics. The question whether the normal heart rate is chaotic or not is an attempt to elucidate the underlying mechanisms of cardiovascular dynamics and therefore a highly controversial topical challenge. In this contribution we demonstrate that linear and nonlinear parameters allow us to separate completely the data sets of the three groups provided for this controversial topic in nonlinear dynamics. The question whether these time series are chaotic or not cannot be answered satisfactorily without investigating the underlying mechanisms leading to them. We give an example of the dominant influence of respiration on heart beat dynamics, which shows that observed fluctuations can be mostly explained by respiratory modulations of heart rate and blood pressure (coefficient of determination: 96%). Therefore, we recommend reformulating the following initial question: "Is the normal heart rate chaotic?" We rather ask the following: " Is the normal heart rate 'chaotic' due to respiration?"
Activated carbon has become a widely used tool to investigate root-mediated allelopathy of plants, especially in plant invasion biology, because it adsorbs and thereby neutralizes root exudates. Allelopathy has been a controversially debated phenomenon for years, which revived in plant invasion biology as one possible reason for the success of invasive plants. Noxious plant exudates may harm other plants and provide an advantage to the allelopathic plant. However, root exudates are not always toxic, but may stimulate the microbial community and change nutrient availability in the rhizosphere. In a greenhouse experiment, we investigated the interacting effects of activated carbon, arbuscular mycorrhiza and plant competition between the invasive Senecio inaequidens and the native Artemisia vulgaris. Furthermore, we tested whether activated carbon showed any undesired effects by directly affecting mycorrhiza or soil chemistry. Contrary to the expectation, S. inaequidens was a weak competitor and we could not support the idea that allelopathy was involved in the competition. Activated carbon led to a considerable increase in the aboveground biomass production and reduced the infection with arbuscular mycorrhiza of both plant species. We expected that arbuscular mycorrhiza promotes plant growth by increasing nutrient availability, but we found the contrary when activated carbon was added. Chemical analyses of the substrate showed, that adding activated carbon resulted in a strong increase in plant available phosphate and in a decrease of the C-organic/N-total ration both of which suggest stimulated microbial activity. Thus, activated carbon not only reduced potential allelopathic effects, but substantially changed the chemistry of the substrate. These results show that activated carbon should be handled with great care in ecological experiments on allelopathy because of possible confounding effects on the soil community.
The effect of introducing positive charges (lysines) in human cytochrome c (cyt c) on the redox properties and reaction rates of cyt c with superoxide radicals was studied. The mutated forms of this electron-transfer protein are used as sensorial recognition elements for the amperometric detection of the reactive oxygen radical. The proteins were prepared by site-directed mutagenesis focusing on amino acids near the heme edge. The 11 mutants of human cyt c expressed in the course of this research have been characterized by UV-vis spectroscopy, circular dichroism, and NMR spectroscopy to verify overall structure integrity as well as axial coordination of the heme iron. The mutants are investigated voltammetrically using promoter-modified gold electrodes with respect to redox activity and formal redox potential. The rate constants for the reaction with superoxide have been determined spectrophotometrically. Four mutants show a higher reaction rate with the radical as compared to the wild type. These mutants are used for the construction of superoxide sensors based on thiol-modified gold electrodes and covalently fixed proteins. We found that the E66K mutant-based electrode has a clearly higher sensitivity in comparison with the wild-type-based sensor while retaining the high selectivity and showing a good storage stability.
Fault zones are the locations where motion of tectonic plates, often associated with earthquakes, is accommodated. Despite a rapid increase in the understanding of faults in the last decades, our knowledge of their geometry, petrophysical properties, and controlling processes remains incomplete. The central questions addressed here in our study of the Dead Sea Transform (DST) in the Middle East are as follows: (1) What are the structure and kinematics of a large fault zone? (2) What controls its structure and kinematics? (3) How does the DST compare to other plate boundary fault zones? The DST has accommodated a total of 105 km of left-lateral transform motion between the African and Arabian plates since early Miocene (similar to 20 Ma). The DST segment between the Dead Sea and the Red Sea, called the Arava/Araba Fault (AF), is studied here using a multidisciplinary and multiscale approach from the mu m to the plate tectonic scale. We observe that under the DST a narrow, subvertical zone cuts through crust and lithosphere. First, from west to east the crustal thickness increases smoothly from 26 to 39 km, and a subhorizontal lower crustal reflector is detected east of the AF. Second, several faults exist in the upper crust in a 40 km wide zone centered on the AF, but none have kilometer-size zones of decreased seismic velocities or zones of high electrical conductivities in the upper crust expected for large damage zones. Third, the AF is the main branch of the DST system, even though it has accommodated only a part (up to 60 km) of the overall 105 km of sinistral plate motion. Fourth, the AF acts as a barrier to fluids to a depth of 4 km, and the lithology changes abruptly across it. Fifth, in the top few hundred meters of the AF a locally transpressional regime is observed in a 100-300 m wide zone of deformed and displaced material, bordered by subparallel faults forming a positive flower structure. Other segments of the AF have a transtensional character with small pull-aparts along them. The damage zones of the individual faults are only 5-20 m wide at this depth range. Sixth, two areas on the AF show mesoscale to microscale faulting and veining in limestone sequences with faulting depths between 2 and 5 km. Seventh, fluids in the AF are carried downward into the fault zone. Only a minor fraction of fluids is derived from ascending hydrothermal fluids. However, we found that on the kilometer scale the AF does not act as an important fluid conduit. Most of these findings are corroborated using thermomechanical modeling where shear deformation in the upper crust is localized in one or two major faults; at larger depth, shear deformation occurs in a 20-40 km wide zone with a mechanically weak decoupling zone extending subvertically through the entire lithosphere.
Point-of-care testing (POCT) is a fast developing area in clinical diagnostics that is considered to be one of the main driving forces for the future in vitro diagnostic market. POCT means decentralized testing at the site of patient care. The most important POCT devices are handheld blood glucose sensors. In some of these sensors, after the application of less than 1 A mu l whole blood, the results are displayed in less than 10 s. For protein determination, the most commonly used devices are based on lateral flow technology. Although these devices are convenient to use, the results are often only qualitative or semiquantitative. The review will illuminate some of the current methods employed in POCT for proteins and will discuss the outlook for techniques (e.g., electrochemical immunosensors) that could have a great impact on future POCT of proteins.
OBJECTIVE: To examine factors associated with the maternal perception of the weight status in related and unrelated children and to examine whether associated health risks for children's physical and mental health are recognized. PATIENTS AND METHODS: Two hundred nineteen mothers with children between 3 and 6 years of age took part in this study. The participating mothers were recruited from inpatient clinics and kindergartens. Parents were presented with 9 silhouettes representing different age- and gender-specific BMI percentiles. Demographic and weight-related variables were assessed with regard to their influence on the accuracy of the maternal weight estimation in general and for their own child. RESULTS: Of the participating mothers, 64.5% identified the overweight silhouettes of preschool- aged children correctly. However, only 48.8% of the mothers identified the overweight silhouettes associated with an increased risk for physical health problems, and 38.7% identified the silhouettes associated with an increased mental health risk. Mothers with a lower educational background were more likely to misclassify the overweight silhouettes and underestimate the associated health problems. For their own child, only 40.3% of the mothers chose silhouettes that were in agreement with the objective weight status of their child. This underestimation was associated with a higher maternal and child weight status but not with a general inability to identify the weight status of children. CONCLUSIONS: Identifying unrelated overweight silhouettes is influenced by maternal education level, whereas estimating their own child's weight status is influenced by the weight status of the mother and the child. Hence, feedback on the child's risk to become overweight is necessary to increase maternal risk awareness and willingness to take part in prevention programs.
Two well known phenomena associated with erupting filaments are the transient coronal holes that form on each side of the filament channel and the bright post-event arcade with its expanding double row of footpoints. Here we focus on a frequently overlooked signature of filament eruptions: the spike- or fan-shaped brightenings that appear to mark the far endpoints of the filament. From a sample of non-active-region filament events observed with the Extreme- Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory, we find that these brightenings usually occur near the outer edges of the transient holes, in contrast to the post-event arcades, which define their inner edges. The endpoints are often multiple and are rooted in and around strong network flux well outside the filament channel, a result that is consistent with the axial field of the filament being much stronger than the photospheric field inside the channel. The extreme ultraviolet brightenings, which are most intense at the time of maximum outward acceleration of the filament, can be used to determine unambiguously the direction of the axial field component from longitudinal magnetograms. Their location near the outer boundary of the transient holes suggests that we are observing the footprints of the current sheet formed at the leading edge of the erupting filament, as distinct from the vertical current sheet behind the filament which is the source of the post-event arcade.
The transmembrane tight junction protein occludin is sensitive to oxidative stress. Occludin oligomerizes; however, its function in the tight junction is unknown. The cytosolic C-terminal tail contains a coiled coil-domain and forms dimers contributing to the oligomerization. The regulation of the oligomerization remains unclear. As the domain area contains sulfhydryl residues, we tested the hypothesis that the dimerization of the coiled coil-domain depends on these residues. We showed that the dimerization is modulated by the thiol concentration in the low-millimolar range, which is relevant both for physiological and pathophysiological conditions. Masking the sulfhydryl residues in the fragment by covalent binding of 4-vinyl pyridine prevented the dimerization but did not affect its helical structure and cylindric shape. The data demonstrate, for the first time, that disulfide bridge formation of murine cystein 408 is involved in the dimerization. This process is redox-sensitive but the secondary structure of the domain is not. It is concluded that the dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self- association. Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization; a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions.
Background: Speech development is frequently impaired in very low birth weight (VLBW) infants. Few and controversial data have been published on concepts regarding the influence of bilingual education. Aims: The objectives of the current study were to assess the influence of parental bilingualism on speech development and neurodevelopmental outcome in low risk VLBW infants. Study design: Monocentric prospective controlled cohort study with standardized follow- up. Subjects: We recruited 50 singleton VLBW infants each from monolingual and bilingual families as well as 90 term control infants. The infants were free of disease and congenital malformation. Outcome measures: Griffiths scales of infant development at the corrected ages of 6 and 12 months, Bayley Scales of Infant Development II (BSID II) with 22 months. Results: In general, both bilingual and monolingual VLBW infants achieved age-specific milestones at the corrected age of 6,12 and 22 months. However, bilingual VLBW infants achieved significantly lower scores than their monolingual peers in all cognitive subscales. The influence of maternal education on the neurodevelopmental outcome of the preterm infants was not significant; the subscales' correlation with socioeconomic or biological parameters was poor. However, a clear differentiation between social status and bilingual environment importance for speech development was not possible. Conclusions: In the setting of the present investigation, parental bilingualism is associated with slower neurodevelopment in VLBW infants during the first 2 years of life.
Carbon assimilation mode in mixotrophs and the fatty acid composition of their rotifer consumers
(2009)
P>1. We examined an important ecophysiological link between the mixotrophic flagellate Chlamydomonas acidophila and its consumers, the rotifers Elosa worallii, Cephalodella sp. and Brachionus sericus, by comparing their fatty acid profiles. 2. The mixotrophic flagellate was grown under either exclusively autotrophic conditions in the light, under exclusively heterotrophic conditions in the dark with an organic carbon source (glucose), or in the light plus the organic carbon sources (=mixotrophic). 3. Under heterotrophic growth conditions, C. acidophila strongly reduced its content of the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA, C18:3n-3) compared with auto- and mixotrophic growth conditions. Although PUFAs with more than 18 carbon atoms were not detected in C. acidophila, significant amounts of eicosatetraenoic (ETA, 20:4n-3) and eicosapentaenoic acid (EPA, 20:5n-3) were found in three rotifer consumers. 4. Species-specific differences in the fatty acid profiles with respect to ETA, EPA and the precursor ALA were found in the rotifers: Brachionus and Cephalodella fed on the heterotrophic diets synthesised less EPA. In Elosa, smaller amounts of ALA were detected but were converted efficiently to a constant content of EPA and to an exceptionally high content of ETA. 5. Since in nature the mode of carbon assimilation among mixotrophic organisms differs, and their fatty acid composition varies depending on their mode of carbon assimilation, the availability of ALA might be critical for their consumers. An insufficient dietary supply of this precursor for the synthesis of ETA and EPA can prevent consumers from regulating their content of ETA and EPA. Therefore, observed differences in values of the latter might underly species-specific differences in the competitive capability of consumers.
Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA.
Peripheral T-cell (TC) tolerance can be induced by tolerogenic antigen-presenting cell (APC). A prerequisite is the reduction or blockade of B7 of APC. Besides dendritic cell, B cells can be used as APC. Here, we show the generation B cells with reduced B7 expression by lentiviral transduction of endoplasmic reticulum (ER)-directed CTLA4. Vectors coding for the human CTL4-Ig were used for the human B-cell line Raji. Transduction efficiency was over 90% (MOI = 3). For the murine B-cell line A20 and for primary mouse B cells, murine CTLA4 was used. We show that B cells with reduced B7 expression reduce the antigen (Ag) specific TC proliferation in vitro. B cells expressing an ER-directed CTLA4 may reduce Ag-specific immune responses.
This paper reports on a project to compare predictions from a range of catchment models applied to a mesoscale river basin in central Germany and to assess various ensemble predictions of catchment streamflow. The models encompass a large range in inherent complexity and input requirements. In approximate order of decreasing complexity, they are DHSVM, MIKE-SHE, TOPLATS, WASIM-ETH, SWAT, PRMS, SLURP, HBV, LASCAM and IHACRES. The models are calibrated twice using different sets of input data. The two predictions from each model are then combined by simple averaging to produce a single-model ensemble. The 10 resulting single-model ensembles are combined in various ways to produce multi-model ensemble predictions. Both the single-model ensembles and the multi-model ensembles are shown to give predictions that are generally superior to those of their respective constituent models, both during a 7-year calibration period and a 9- year validation period. This occurs despite a considerable disparity in performance of the individual models. Even the weakest of models is shown to contribute useful information to the ensembles they are part of. The best model combination methods are a trimmed mean (constructed using the central four or six predictions each day) and a weighted mean ensemble (with weights calculated from calibration performance) that places relatively large weights on the better performing models. Conditional ensembles. in which separate model weights are used in different system states (e.g. summer and winter, high and low flows) generally yield little improvement over the weighted mean ensemble. However a conditional ensemble that discriminates between rising and receding flows shows moderate improvement. An analysis of ensemble predictions shows that the best ensembles are not necessarily those containing the best individual models. Conversely, it appears that some models that predict well individually do not necessarily combine well with other models in multi-model ensembles. The reasons behind these observations may relate to the effects of the weighting schemes, non- stationarity of the climate series and possible cross-correlations between models.
External climate forcings-such as long-term changes in solar insolation-generate different climate responses in tropical and high latitude regions(1). Documenting the spatial and temporal variability of past climates is therefore critical for understanding how such forcings are translated into regional climate variability. In contrast to the data- richmiddle and high latitudes, high-quality climate-proxy records from equatorial regions are relatively few(2-4), especially from regions experiencing the bimodal seasonal rainfall distribution associated with twice-annual passage of the Intertropical Convergence Zone. Here we present a continuous and well-resolved climate-proxy record of hydrological variability during the past 25,000 years from equatorial East Africa. Our results, based on complementary evidence from seismic-reflection stratigraphy and organic biomarker molecules in the sediment record of Lake Challa near Mount Kilimanjaro, reveal that monsoon rainfall in this region varied at half-precessional (similar to 11,500-year) intervals in phase with orbitally controlled insolation forcing. The southeasterly and northeasterly monsoons that advect moisture from the western Indian Ocean were strengthened in alternation when the inter-hemispheric insolation gradient was at a maximum; dry conditions prevailed when neither monsoon was intensified and modest local March or September insolation weakened the rain season that followed. On sub-millennial timescales, the temporal pattern of hydrological change on the East African Equator bears clear high-northern-latitude signatures, but on the orbital timescale it mainly responded to low-latitude insolation forcing. Predominance of low-latitude climate processes in this monsoon region can be attributed to the low-latitude position of its continental regions of surface air flow convergence, and its relative isolation from the Atlantic Ocean, where prominent meridional overturning circulation more tightly couples low-latitude climate regimes to high-latitude boundary conditions.
The femtosecond-laser-induced, substrate-mediated associative desorption of molecular hydrogen and deuterium from a Ru(0001) surface in the so-called DIMET limit is studied theoretically. Two widely used models, a "quantum nonadiabatic" approach and a "classical adiabatic" one are employed and compared to each other. The quantum model is realized by the Monte Carlo wave packet (MCWP) method in the framework of open-system density matrix theory: The classical approach is realized with the help of (frictional) Langevin dynamics with stochastic forces. For both models the same ground-state potential energy surface is used and the same two-temperature model adopted to describe the hot- electron-driven desorption dynamics. Apart from these common features both models are different. Still, both account well for the main experimental findings (Wagner et al. Phys. Rev. B 2005, 72, 205404). In particular, an isotope effect in desorption probabilities, the energy content of the desorbing molecules, and the scaling of these observables with laser fluence are reproduced and explained. The similarity of the results obtained with both models is traced back to the fact that, in the present case, the photodynamics takes place dominantly in the ground electronic state because the electronically excited state is rapidly quenched. The short lifetime of the excited state has also the effect that photoreaction cross sections are typically very small. An IR+vis hybrid scheme, by which the adsorbate is vibrationally excited by IR photons prior to the heating of metal electrons with the vis pulse, is shown to successfully promote the reaction even for strongly coupled adsorbate-surface systems.
Neogene magmatism and its possible causal relationship with hydrocarbon generation in SW Colombia
(2009)
The Cretaceous oil-bearing source and reservoir sedimentary succession in the Putumayo Basin, SW Colombia, was intruded by gabbroic dykes and sills. The petrological and geochemical character of the magmatic rocks shows calc- alkaline tendency, pointing to a subduction-related magmatic event. K/Ar dating of amphibole indicates a Late Miocene to Pliocene age (6.1 +/- A 0.7 Ma) for the igneous episode in the basin. Therefore, we assume the intrusions to be part of the Andean magmatism of the Northern Volcanic Zone (NVZ). The age of the intrusions has significant tectonic and economic implications because it coincides with two regional events: (1) the late Miocene/Pliocene Andean orogenic uplift of most of the sub-Andean regions in Peru, Ecuador and Colombia and (2) a pulse of hydrocarbon generation and expulsion that has reached the gas window. High La/Yb, K/Nb and La/Nb ratios, and the obtained Sr-Nd-Pb isotopic compositions suggest the involvement of subducted sediments and/or the assimilation of oceanic crust of the subducting slab. We discuss the possibility that magma chamber(s) west of the basin, below the Cordillera, did increase the heat flow in the basin causing generation and expulsion of hydrocarbons and CO2.
The Subandean fold and thrust belt of Bolivia constitutes the easternmost part of the Andean orogen that reflects thin-skinned shortening and eastward propagation of the Andean deformation front. The exact interplay of tectonics, climate, and erosion in the deposition of up to 7.5 km of late Cenozoic strata exposed in the Subandes remains unclear. To better constrain these relationships, we use four W-E industry seismic reflection profiles, eight new zircon U-Pb ages from Mio-Pliocene sedimentary strata, and cross-section balancing to evaluate the rates of thrust propagation, shortening, and deposition pinch-out migration. Eastward thrusting arrived in the Subandean belt at similar to 12.4 +/- 0.5 Ma and propagated rapidly toward the foreland unit approximately 6 Ma. This was followed by out-of- sequence deformation from ca. 4 to 2.1 Ma and by renewed eastward propagation thereafter. Our results show that the thrust-front propagation- and deposition pinch-out migration rates mimic the sediment accumulation rate. The rates of deposition pinchout migration and thrust propagation increased three- and two fold, respectively (8 mm/a; 3.3 mm/a) at 86 Ma. The three-fold increase in deposition pinch-out migration rate at this time is an indication of enhanced erosional efficiency in the hinterland, probably coupled with flexural rebound of the basin. Following the pulse of pinch-out migration, the Subandean belt witnessed rapid similar to 80 km eastward propagation of thrusting to the La Vertiente structure at 6 Ma. As there is no evidence for this event of thrust front migration being linked to an increase in shortening rate, the enhanced frontal accretion suggests a shift to supercritical wedge taper conditions. We propose that the supercritical state was due to a drop in basal strength, caused by sediment loading and pore fluid overpressure. This scenario implies that climate-controlled variation in erosional efficiency was the driver of late Miocene mass redistribution, which induced flexural rebound of the Subandean thrust belt, spreading of a large clastic wedge across the basin, and subsequent thrust-front propagation.
Recognition of an inferred Miocene marine incursion affecting areas from Colombia through Peru and Bolivia and into Argentina is essential to delineate the South American Seaway. In Bolivia, corresponding strata of inferred marine origin have been assigned to the late Miocene Yecua Formation. We carried out high-resolution delta C-13 and delta O-18 isotopic studies on 135 in situ carbonates from 3 outcrops, combined with detailed sedimentologic, paleontologic, and ichnologic analysis. Four less negative delta C-13 excursion levels were recorded that coincide well with beds containing marine body (barnacle) and trace (Ophiomorpha) fossils. These strata are interbedded with red-green beds containing mudcracks, plant roots, gypsum, and trace fossils of the continental Scoyenia ichnofacies. Our data are significant in that they show for the first time four possible short-lived marine incursions in the Bolivian central Andes during the late Miocene. The result is constrained by a new U-Pb date of 7.17 +/- 0.34 Ma at the top of Yecua strata.
Many of today's distributed computing systems in the field do not Support the migration of execution entities among computing nodes (luring runtime. The relatively static association between units of processing and computing nodes makes it difficult to implement fault-tolerant behavior or load-balancing schemes. The concept of code migration may provide a solution to the above-mentioned problems. it can be defined as the movement of processes, objects, or components from one computing node to another during system runtime in a distributed environment. With the advent of the virtual machine-based NET framework, many of the cross-language heterogeneity issues have been resolved. With the commercial implementation, the shared source "Rotor", and the open-source "Mono" implementation on hand, we have focused on cross-operating system heterogeneity issues and present interoperability and migration schemes for applications distributed over different operating systems (namely Linux and Windows 2000) as well as various NET implementations. Within this paper, we describe the integration of a migration facility with the hell) of Aspect- Oriented Programming (AOP) into the NET framework. AOP is interesting as it addresses non-functional system properties on the middleware level, without the need to manipulate lower system layers like the operating system itself. Most features required to implement object or process migration (such as reflection mechanisms or a machine-independent executable format) are already present in the NET frameworks, so the integration of such a concept is a natural extension of the system capabilities. We have implemented several proof-of-concept applications for different use case scenarios. The paper contains an experimental evaluation of the performance impact of object migration in context of those applications.
Tree size and herbivory determine below-canopy grass quality and species composition in savannahs
(2009)
Large single-standing trees are rapidly declining in savannahs, ecosystems supporting a high diversity of large herbivorous mammals. Savannah trees are important as they support both a unique flora and fauna. The herbaceous layer in particular responds to the structural and functional properties of a tree. As shrubland expands stem thickening occurs and large trees are replaced by smaller trees. Here we examine whether small trees are as effective in providing advantages for grasses growing beneath their crowns as large trees are. The role of herbivory in this positive tree- grass interaction is also investigated. We assessed soil and grass nutrient content, structural properties, and herbaceous species composition beneath trees of three size classes and under two grazing regimes in a South African savannah. We found that grass leaf content (N and P) beneath the crowns of particularly large (ca. 3.5 m) and very large trees (ca. 9 m) was as much as 40% greater than the same grass species not growing under a tree canopy, whereas nutrient contents of grasses did not differ beneath small trees (< 2.3 m). Moderate herbivory enhanced these effects slightly. Grass species composition differed beneath and beyond the tree canopy but not between tree size classes. As large trees significantly improve the grass nutrient quality for grazers in contrast to smaller trees, the decline of the former should be halted. The presence of trees further increases grass species diversity and patchiness by favouring shade- tolerant species. Both grazing wildlife and livestock will benefit from the presence of large trees because of their structural and functional importance for savannahs.
A theoretical model for the selective subsurface absorption of atomic hydrogen in a Pd(111) surface by infrared (IR) laser pulses is presented. The dynamics of the adsorbate is studied within the reduced density matrix approach. Energy and phase relaxation of the hydrogen atom are treated using the semigroup formalism. The vibrational excitation leading to subsurface absorption is performed using rationally designed pulses as well as IR laser pulses optimized on- the-fly. It is shown that dissipation can be used as a tool to transfer population to an otherwise inaccessible state via a mechanism known as "laser distillation." We demonstrate that when the reaction path is generalized from a reduced one-dimensional to full three-dimensional treatment of the system, the laser control strategy can prove very different.
Evolutionary processes play an important role in shaping the dynamics of range expansions, and selection on dispersal propensity has been demonstrated to accelerate rates of advance. Previous theory has considered only the evolution of unconditional dispersal rates, but dispersal is often more complex. For example, many species emigrate in response to crowding. Here, we use an individual-based model to investigate the evolution of density dependent dispersal into empty habitat, such as during an invasion. The landscape is represented as a lattice and dispersal between Populations follows a stepping-stone pattern. Individuals carry three 'genes' that determine their dispersal strategy when experiencing different population densities. For a stationary range we obtain results consistent with previous theoretical studies: few individuals emigrate from patches that are below equilibrium density. However, during the range expansion of a previously stationary population, we observe evolution towards dispersal strategies where considerable emigration occurs well below equilibrium density. This is true even for moderate costs to dispersal, and always results in accelerating rates of range expansion. Importantly, the evolution we observe at an expanding front depends upon fitness integrated over several generations and cannot be predicted by a consideration of lifetime reproductive success alone. We argue that a better understanding of the role of density dependent dispersal, and its evolution, in driving population dynamics is required especially within the context of range expansions.
Owen et al. [Owen. R.B.. Potts, R., Behrensmeyer, A.K., Ditchfield, P. 2008. Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation, southern Kenya Rift Valley. Palaeogeography, Palaeochmatology, Palaeoccology, 269. 17-37], Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation. southern Kenya Rift. Palaeogeography Palaeoclimatology Palaeciecology, 269, 17-37) argued that diatom assemblage variations in the Olorgesailie Formation indicate considerable environmental instability with both wetter and drier periods, contradicting the proposed period of lake stability and wet climatic conditions between ca 11 and 0.9 million years ago as proposed by Trauth et al [Trauth, M.H. Maslin, MA.. Demo. A.. Strecker, M R.. 2005. Late Cenozoic moisture history of East Africa. Science 309. 2051-2053., Trauth, M H. Mashn. M.A., Deino, A., Bergner. A G.N.. Diihnforth, M. Strecker. M.R, 2007 High- and low-latitude forcing of Plio-Pleistocene East African climate and hL.man evolution. journal of Human Evolution 53, 475-486] Contrary to the interpretation of our work by O Nen et al. [Owen. R.B, Potts, R. Behrensmeyer, A.K. Ditchfield. P. 2008], we never said that the proposed periods of large lakes were characterized by stable conditions.
The Kuramoto phase-diffusion equation is a nonlinear partial differential equation which describes the spatiotemporal evolution of a phase variable in an oscillatory reaction-diffusion system. Synchronization manifests itself in a stationary phase gradient where all phases throughout a system evolve with the same velocity, the synchronization frequency. The formation of concentric waves can be explained by local impurities of higher frequency which can entrain their surroundings. Concentric waves in synchronization also occur in heterogeneous systems, where the local frequencies are distributed randomly. We present a perturbation analysis of the synchronization frequency where the perturbation is given by the heterogeneity of natural frequencies in the system. The nonlinearity in the form of dispersion leads to an overall acceleration of the oscillation for which the expected value can be calculated from the second-order perturbation terms. We apply the theory to simple topologies, like a line or sphere, and deduce the dependence of the synchronization frequency on the size and the dimension of the oscillatory medium. We show that our theory can be extended to include rotating waves in a medium with periodic boundary conditions. By changing a system parameter, the synchronized state may become quasidegenerate. We demonstrate how perturbation theory fails at such a critical point.
The behavior of weakly coupled self-sustained oscillators can often be well described by phase equations. Here we use the paradigm of Kuramoto phase oscillators which are coupled in a network to calculate first- and second-order corrections to the frequency of the fully synchronized state for nonidentical oscillators. The topology of the underlying coupling network is reflected in the eigenvalues and eigenvectors of the network Laplacian which influence the synchronization frequency in a particular way. They characterize the importance of nodes in a network and the relations between them. Expected values for the synchronization frequency are obtained for oscillators with quenched random frequencies on a class of scale-free random networks and for a Erdoumls-Reacutenyi random network. We briefly discuss an application of the perturbation theory in the second order to network structural analysis.