978 research outputs found

    Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing

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    Acknowledgements The authors thank Gabriele Kirchhof, Silke Werner, Klaus Gerling and Karsten Knop from the Institute of Animal Welfare and Animal Husbandry of the Friedrich-Loeffler-Institut for technical help and Catherine Hambly from the Institute of Biological and Environmental Sciences of the University of Aberdeen for the isotope analysis. Financial support statement This research received no specific grant from any funding agency, commercial or not-for-profit sectionPeer reviewedPublisher PD

    Analyses of Genetic Change in Grass-Clover Based Systems Over Time

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    Since the use of nitrogen fertilisers is reduced, swards based on grass-clover mixtures regain importance in grassland production. Management of these swards is more complicated than the management of pure grass swards. The population structure will develop in response to abiotic and biotic stresses. In this study we will test the genetic change in the clover components of grass-clover mixtures

    VerÀnderungen der ZustandsnÀhrkraftstufe (SEA95) brandenburgischer Waldböden

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    Im nordostdeutschen Standortserkundungsverfahren nach „SEA95“ (Schulze 1996) wird der chemische Oberbodenzustand von Waldstandorten durch eine integrierende ZustandsnĂ€hrkraftstufe gekennzeichnet, welche sich anhand der aus dem C/N-VerhĂ€ltnis abgeleiteten Stickstoffstufe und der aus pH-Wert bzw. BasensĂ€ttigung ermittelten Basenstufe ergibt. Von Kopp & Schwanecke (1994) wurden „harmonische Relationen“ zwischen SĂ€ure-Basen- und Stickstoffstufen definiert, die sich in natĂŒrlichen Waldökosystemen unter Gleichgewichtsbedingungen von Standort und Vegetation einstellen wĂŒrden. Disharmonische OberbodenzustĂ€nde waren in der Vergangenheit vor allem durch hohe atmogene FremdstoffeintrĂ€ge, insbesondere basische StaubeintrĂ€ge aus der Braunkohleverbrennung in den 1970er und 1980er Jahren sowie Stickstoffdepositionen aus Landwirtschaft und Verkehr bedingt. Anhand der Daten der ersten und zweiten bundesweiten Bodenzustandserhebung im Wald (BZE-1: 1992, BZE-2: 2007) werden fĂŒr das Land Brandenburg ZustandsnĂ€hrkraftstufen vergleichend dargestellt und VerĂ€nderungen des Oberbodenzustandes erlĂ€utert. Die konstatierte Bodenversauerung bei gleichzeitig erweiterten C/N-VerhĂ€ltnissen kann formal dahingehend gedeutet werden, dass sich im Zeitraum zwischen den Inventuren tendenziell wieder naturnĂ€here ZustĂ€nde eingestellt haben. Zur Zeit der BZE-1 konnte fĂŒr 39 % der BZE-Stichprobe ein Gleichgewicht zwischen SĂ€ure- und Basenstufe konstatiert werden, bei der BZE-2 fĂŒr 61 %. Die FĂ€lle mit disharmonischen Relationen aufgrund von erhöhten Stickstoffwerten haben sich kaum verĂ€ndert (BZE-1: 15 % der Punkte, BZE-2: 16 %). Deutlich hat indes die Zahl disharmonischer VerhĂ€ltnisse aufgrund von erhöhten Basenstufen zwischen den Inventuren abgenommen (BZE-1: 46 %, BZE-2: 23 %)

    Debye mass and heavy quark potential in a PNJL quark plasma

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    We calculate the Debye mass for the screening of the heavy quark potential in a plasma of massless quarks coupled to the temporal gluon background governed by the Polyakov loop potential within the PNJL model in RPA approximation. We give a physical motivation for a recent phenomenological fit of lattice data by applying the calculated Debye mass with its suppression in the confined phase due to the Polyakov-loop to a description of the temperature dependence of the singlet free energy for QCD with a heavy quark pair at infinite separation. We compare the result to lattice data.Comment: 6 pages, 1 figure, contribution to Proceedings of the 6th International Conference on "Critical Point and Onset of Deconfinement", to appear in Phys. At. Nucl., vol. 7

    Triggering Mechanisms for Motor Actions: The Effects of Expectation on Reaction Times to Intense Acoustic Stimuli

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    Motor actions can be released much sooner than normal when the go-signal is of very high intensity (>100 dBa). Although statistical evidence from individual studies has been mixed, it has been assumed that sternocleidomastoid (SCM) muscle activity could be used to distinguish between two neural circuits involved in movement triggering. We summarized meta-analytically the available evidence for this hypothesis, comparing the difference in premotor reaction time (RT) of actions where SCM activity was elicited (SCM+ trials) by loud acoustic stimuli against trials in which it was absent (SCM- trials). We found ten studies, all reporting comparisons between SCM+ and SCM- trials. Our mini meta-analysis showed that premotor RTs are faster in SCM+ than in SCM- trials, but the effect can be confounded by the variability of the foreperiods employed. We present experimental data showing that foreperiod predictability can induce differences in RT that would be of similar size to those attributed to the activation of different neurophysiological pathways to trigger prepared actions. We discuss plausible physiological mechanisms that would explain differences in premotor RTs between SCM+ and SCM- trials

    A Receptor-based Switch that Regulates Anthrax Toxin Pore Formation

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    Cellular receptors can act as molecular switches, regulating the sensitivity of microbial proteins to conformational changes that promote cellular entry. The activities of these receptor-based switches are only partially understood. In this paper, we sought to understand the mechanism that underlies the activity of the ANTXR2 anthrax toxin receptor-based switch that binds to domains 2 and 4 of the protective antigen (PA) toxin subunit. Receptor-binding restricts structural changes within the heptameric PA prepore that are required for pore conversion to an acidic endosomal compartment. The transfer cross-saturation (TCS) NMR approach was used to monitor changes in the heptameric PA-receptor contacts at different steps during prepore-to-pore conversion. These studies demonstrated that receptor contact with PA domain 2 is weakened prior to pore conversion, defining a novel intermediate in this pathway. Importantly, ANTXR2 remained bound to PA domain 4 following pore conversion, suggesting that the bound receptor might influence the structure and/or function of the newly formed pore. These studies provide new insights into the function of a receptor-based molecular switch that controls anthrax toxin entry into cells

    Dynamics of Resonances in Strongly Interacting Systems

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    The effects of the propagation of particles which have a finite life-time and an according broad distribution in their mass spectrum are discussed in the context of a transport descriptions. In the first part some example cases of mesonic modes in nuclear matter at finite densities and temperatures are presented. These equilibrium calculations illustrate the dynamical range of spectral distributions to be adequately covered by non-equilibrium description of the dynamics of two nuclei colliding at high energies. The second part addresses the problem of transport descriptions which properly account for the damping width of the particles. A systematic and general gradient approximation is presented in the form of diagrammatic rules which permit to derive a self-consistent transport scheme from the Kadanoff--Baym equation. The scheme is conserving and thermodynamically consistent provided the self-energies are obtained within the Phi-derivable two-particle irreducible (2PI) method of Baym. The merits, the limitations and partial cures of the limitations of this transport scheme are discussed in detail.Comment: To appear in the proceedings of the International Conference "Progress in Nonequilibrium Green's Functions III", Kiel, 22.-26. August 200

    Evaluating chiral symmetry restoration through the use of sum rules

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    We pursue the idea of assessing chiral restoration via in-medium modifications of hadronic spectral functions of chiral partners. The usefulness of sum rules in this endeavor is illustrated, focusing on the vector and axial-vector channels. We first present an update on constructing quantitative results for pertinent vacuum spectral functions. These spectral functions serve as a basis upon which the in-medium spectral functions can be constructed. A striking feature of our analysis of the vacuum spectral functions is the need to include excited resonances, dictated by satisfying the Weinberg-type sum rules. This includes excited states in both the vector and axial-vector channels. Preliminary results for the finite temperature vector spectral function are presented. Based on a rho spectral function tested in dilepton data which develops a shoulder at low energies, we find that the rho' peak flattens off. The flattening may be a sign of chiral restoration, though a study of the finite temperature axial-vector spectral function remains to be carried out.Comment: 9 pages, conference proceedings from Resonance Workshop at UT Austin, March 5-7 201

    Detection of cerebral tauopathy in P301L mice using high-resolution large-field multifocal illumination fluorescence microscopy

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    Current intravital microscopy techniques visualize tauopathy with high-resolution, but have a small field-of-view and depth-of-focus. Herein, we report a transcranial detection of tauopathy over the entire cortex of P301L tauopathy mice using large-field multifocal illumination (LMI) fluorescence microscopy technique and luminescent conjugated oligothiophenes. In vitro assays revealed that fluorescent ligand h-FTAA is optimal for in vivo tau imaging, which was confirmed by observing elevated probe retention in the cortex of P301L mice compared to non-transgenic littermates. Immunohistochemical staining further verified the specificity of h-FTAA to detect tauopathy in P301L mice. The new imaging platform can be leveraged in pre-clinical mechanistic studies of tau spreading and clearance as well as longitudinal monitoring of tau targeting therapeutics
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