978 research outputs found
Daily energy expenditure and water turnover in two breeds of laying hens kept in floor housing
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
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
Im nordostdeutschen Standortserkundungsverfahren nach âSEA95â (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 âharmonische Relationenâ 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
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
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
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
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
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
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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