663 research outputs found
Gapless Hartree-Fock Resummation Scheme for the O(N) Model
A modified selfconsistent Hartree-Fock approximation to the lambda*phi^4
theory with spontaneously broken O(N) symmetry is proposed. It preserves all
the desirable features, like conservation laws and thermodynamic consistency,
of the selfconsistent Dyson scheme generated from a 2PI functional, also known
as the Phi-derivable scheme, while simultaneously respecting the
Nambu-Goldstone theorem in the chiral-symmetry broken phase. Various
approximate resummation schemes are discussed.Comment: 13 pages, 10 figures / Version accepted by Phys. Rev. D: the
introduction has been expanded by a few remarks in order to further clarify
the goal of the pape
Computation of emotions
When people talk to each other, they express their feelings through facial expressions, tone of voice, body postures and gestures. They even do this when they are interacting with machines. These hidden signals are an important part of human communication, but most computer systems ignore them. Emotions need to be considered as an important mode of communication between people and interactive systems. Affective computing has enjoyed considerable success over the past 20 years, but many challenges remain.This is the author's accepted manuscript. The final version is available from ACM in ACM International Conference on Multimodal Interaction published at http://dl.acm.org/citation.cfm?id=2669638
Quarkonia and Heavy-Quark Relaxation Times in the Quark-Gluon Plasma
A thermodynamic T-matrix approach for elastic 2-body interactions is employed
to calculate spectral functions of open and hidden heavy-quark systems in the
Quark-Gluon Plasma. This enables the evaluation of quarkonium bound-state
properties and heavy-quark diffusion on a common basis and thus to obtain
mutual constraints. The two-body interaction kernel is approximated within a
potential picture for spacelike momentum transfers. An effective
field-theoretical model combining color-Coulomb and confining terms is
implemented with relativistic corrections and for different color channels.
Four pertinent model parameters, characterizing the coupling strengths and
screening, are adjusted to reproduce the color-average heavy-quark free energy
as computed in thermal lattice QCD. The approach is tested against vacuum
spectroscopy in the open (D, B) and hidden (Psi and Upsilon) flavor sectors, as
well as in the high-energy limit of elastic perturbative QCD scattering.
Theoretical uncertainties in the static reduction scheme of the 4-dimensional
Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are
used to calculate Euclidean correlators which are discussed in light of lattice
QCD results, while heavy-quark relaxation rates and diffusion coefficients are
extracted utilizing a Fokker-Planck equation.Comment: 33 pages, 28 figure
Breeding of CMS-F1-Hybrids in \u3cem\u3eLolium Perenne\u3c/em\u3e With Improved Nitrogen Use Efficiency
The environmental pollution by nitrogen losses from dairy farms can be reduced by improving the nitrogen use efficiency (NUE) of grass varieties. The main goal is to develop varieties with a better nitrogen utilisation. These low input varieties can produce acceptable yields at a low level of N-fertilisation. High input varieties express their high yield potential only at high N-supply. These varieties are less preferable, because N- losses increase at higher levels of nitrogen application. The breeding of CMS-F1-Hybrids can be a successful strategy for developing varieties with a higher NUE. In F1-Hybrid varieties higher heterosis effects can be achieved than in populations or synthetic varieties
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
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
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
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