24,810 research outputs found
An analytic Approach to Turaev's Shadow Invariant
In the present paper we extend the "torus gauge fixing approach" by Blau and
Thompson (Nucl. Phys. B408(1):345--390, 1993) for Chern-Simons models with base
manifolds M of the form M= \Sigma x S^1 in a suitable way. We arrive at a
heuristic path integral formula for the Wilson loop observables associated to
general links in M. We then show that the right-hand side of this formula can
be evaluated explicitly in a non-perturbative way and that this evaluation
naturally leads to the face models in terms of which Turaev's shadow invariant
is defined.Comment: 44 pages, 2 figures. Changes have been made in Sec. 2.3, Sec 2.4,
Sec. 3.4, and Sec. 3.5. Appendix C is ne
A Bernstein-type operator approximating continuous functions on the semi-axis
AbstractThe authors present a Bernstein-type operator Ln which is given by a finite sum and defined on the space C(0,∞). It is shown that Ln defines a positive linear operator such that Lnf(x) tends pointwise on [0, ∞) to f(x) for n → ∞. Moreover, estimations for the rate of convergence of Lnf(x)−f(x) are established, measured in terms of the second modulus of continuity of f
STATISTICAL ISSUES IN STUDIES OF THERMOREGULATION IN FARM ANIMALS
Patterns of tympanic temperature response were identified in ad-lib-fed cattle exposed to constant or cyclic (±7 C) conditions at two levels of air temperature: 10 C and 28 C. Use of time series analysis following the DDS approach of Pandit and Wu indicate the thermoregulatory control dynamics for steers at 28±7 C were markedly different from those at the other conditions. Preliminary evaluations using the ideas of chaos and non-linear dynamics show promise of further characterization of stress responses in farm animals
Isoscaling Studies of Fission - a Sensitive Probe into the Dynamics of Scission
The fragment yield ratios were investigated in the fission of 238,233U
targets induced by 14 MeV neutrons. The isoscaling behavior was typically
observed for the isotopic chains of fragments ranging from the proton-rich to
the most neutron-rich ones. The observed high sensitivity of neutron-rich heavy
fragments to the target neutron content suggests fission as a source of
neutron-rich heavy nuclei for present and future rare ion beam facilities,
allowing studies of nuclear properties towards the neutron drip-line and
investigations of the conditions for nucleosynthesis of heavy nuclei. The
breakdowns of the isoscaling behavior around N=62 and N=80 manifest the effect
of two shell closures on the dynamics of scission. The shell closure around
N=64 can be explained by the deformed shell. The investigation of isoscaling in
the spontaneous fission of 248,244Cm further supports such conclusion. The
Z-dependence of the isoscaling parameter exhibits a structure which can be
possibly related to details of scission dynamics. The fission isoscaling
studies can be a suitable tool for the investigation of possible new pathways
to synthesize still heavier nuclei.Comment: 7 pages, 3 figures, RevTex, final version, to appear in Phys. Rev. C
as a regular articl
Livestock production system management responses to thermal challenges
The adaptive capabilities of animals and livestock production systems have been emphasized in this report. Biometeorology has a key role in rational management to meet the challenges of thermal environments. While the focus is primarily on cattle in warm or hot climates, the importance of dynamic animal responses to environmental challenges applies to all species and climates. Methods used to mitigate environmental challenges focus on heat loss/heat production balance. Under cold stress, reduction of heat loss is the key. Under heat stress, reduction of heat load or increasing heat loss are the primary management tools, although heat-tolerant animals are also available. In general, livestock with health problems and the most productive animals (e.g., highest growth rate or milk production) are at greatest risk of heat stress, thereby requiring the most attention. Risk management, by considering perceived thermal challenges, then assessing the potential consequences and acting accordingly, will reduce the impact of such challenges. Appropriate actions include: shade, sprinkling, air movement, or active cooling. Summarizing, the most important element of proactive environmental management to reduce risk is preparation: be informed, develop a strategic plan, observe and recognize animals in distress, and take appropriate tactical action
Hints of theta_13>0 from global neutrino data analysis
Nailing down the unknown neutrino mixing angle theta_13 is one of the most
important goals in current lepton physics. In this context, we perform a global
analysis of neutrino oscillation data, focusing on theta_13, and including
recent results [Neutrino 2008, Proceedings of the XXIII International
Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand,
2008 (unpublished)]. We discuss two converging hints of theta_13>0, each at the
level of ~1sigma: an older one coming from atmospheric neutrino data, and a
newer one coming from the combination of solar and long-baseline reactor
neutrino data. Their combination provides the global estimate sin^2(theta_13) =
0.016 +- 0.010 (1sigma), implying a preference for \theta_13>0 with
non-negligible statistical significance (~90% C.L.). We discuss possible
refinements of the experimental data analyses, which might sharpen such
intriguing indication.Comment: Minor changes in the text. Matches published version in PR
Project {\tt SANC} (former {\tt CalcPHEP}): Support of Analytic and Numeric calculations for experiments at Colliders
The project, aimed at the theoretical support of experiments at modern and
future accelerators -- TEVATRON, LHC, electron Linear Colliders (TESLA, NLC,
CLIC) and muon factories, is presented. Within this project a four-level
computer system is being created, which must automatically calculate, at the
one-loop precision level the pseudo- and realistic observables (decay rates and
event distributions) for more and more complicated processes of elementary
particle interaction, using the principle of knowledge storing.
It was already used for a recalculation of the EW radiative corrections for
Atomic Parity Violation [1] and complete one-loop corrections for the process
[2-4]; for the latter an, agreement up to 11 digits with
FeynArts and the other results is found. The version of {\tt SANC} that we
describe here is capable of automatically computing the decay rates and the
distributions for the decays in the one-loop
approximation.Comment: 3 Latex, Presented at ICHEP2002, Amsterdam, July 24-30, 2000;
Submitted to Proceeding
J_AW,WA functions in Passarino-Veltman reduction
In this paper we continue to study a special class of Passarino-Veltman
functions J arising at the reduction of infrared divergent box diagrams. We
describe a procedure of separation of two types of singularities, infrared and
mass singularities, which are absorbed in simple C0 functions. The infrared
divergences of C0's can be regularized then by any method: photon mass,
dimensionally or by the width of an unstable particle. Functions J, in turn,
are represented as certain linear combinations of the standard D0 and C0
Passarino-Veltman functions. The former are free of both types of singularities
and are expressed as explicit and compact linear combinations of logarithms and
dilogarithm functions. We present extensive comparisons of numerical results
with those obtained with the aid of the LoopTools package
SPLINE MODELS FOR ESTIMATING HEAT STRESS THRESHOLDS IN CATTLE
Studies of the relationship between animal body temperature and air temperature suggest body temperature is essentially unresponsive until a threshold is reached, then it responds dramatically to increasing air temperature. The goal is to estimate the threshold between the thermoneutral plateau and the beginning of the heat stress challenge. One approach is to fit a polynomial to estimate the knot position and use spline functions to perform linear least squares piecewise polynomial fitting. Another alternative is to use nonlinear regression to estimate the knot or an inflection point of a nonlinear function. In both approaches the cyclic nature of body temperature is ignored. This paper explores the use of nonlinear regression to estimate the knot position and handles the hysteresis effect resulting from the cyclic nature of body temperature. Models are fit to data collected from cattle in chambers subjected to semicontrolled sinusoidal air temperature at the University of Missouri-Columbia Animal Science department and a procedure for estimating the heat stress threshold is proposed
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