526 research outputs found
Color Fields on the Light-Shell
We study the classical color radiation from very high energy collisions that
produce colored particles. In the extreme high energy limit, the classical
color fields are confined to a light-shell expanding at and are associated
with a non-linear -model on the 2D light-shell with specific symmetry
breaking terms. We argue that the quantum version of this picture exhibits
asymptotic freedom and may be a useful starting point for an effective
light-shell theory of the structure between the jets at a very high energy
collider.Comment: 11 pages, no figure
Leg disorders in broiler chickens : prevalence, risk factors and prevention
Broiler (meat) chickens have been subjected to intense genetic selection. In the past 50 years, broiler growth rates have increased
by over 300% (from 25 g per day to 100 g per day). There is growing societal concern that many broiler chickens have impaired
locomotion or are even unable to walk. Here we present the results of a comprehensive survey of commercial flocks which
quantifies the risk factors for poor locomotion in broiler chickens.We assessed the walking ability of 51,000 birds, representing 4.8
million birds within 176 flocks.We also obtained information on approximately 150 different management factors associated with
each flock. At a mean age of 40 days, over 27.6% of birds in our study showed poor locomotion and 3.3% were almost unable to
walk. The high prevalence of poor locomotion occurred despite culling policies designed to remove severely lame birds from
flocks. We show that the primary risk factors associated with impaired locomotion and poor leg health are those specifically
associated with rate of growth. Factors significantly associated with high gait score included the age of the bird (older birds), visit
(second visit to same flock), bird genotype, not feeding whole wheat, a shorter dark period during the day, higher stocking density
at the time of assessment, no use of antibiotic, and the use of intact feed pellets. The welfare implications are profound. Worldwide
approximately 261010 broilers are reared within similar husbandry systems.We identify a range of management factors that could
be altered to reduce leg health problems, but implementation of these changes would be likely to reduce growth rate and
production. A debate on the sustainability of current practice in the production of this important food source is required
Universal restrictions to the conversion of heat into work derived from the analysis of the Nernst theorem as a uniform limit
We revisit the relationship between the Nernst theorem and the Kelvin-Planck
statement of the second law. We propose that the exchange of entropy uniformly
vanishes as the temperature goes to zero. The analysis of this assumption shows
that is equivalent to the fact that the compensation of a Carnot engine scales
with the absorbed heat so that the Nernst theorem should be embedded in the
statement of the second law.
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Se analiza la relaci{\'o}n entre el teorema de Nernst y el enunciado de
Kelvin-Planck del segundo principio de la termodin{\'a}mica. Se{\~n}alamos el
hecho de que el cambio de entrop{\'\i}a tiende uniformemente a cero cuando la
temperatura tiende a cero. El an{\'a}lisis de esta hip{\'o}tesis muestra que es
equivalente al hecho de que la compensaci{\'o}n de una m{\'a}quina de Carnot
escala con el calor absorbido del foco caliente, de forma que el teorema de
Nernst puede derivarse del enunciado del segundo principio.Comment: 8pp, 4 ff. Original in english. Also available translation into
spanish. Twocolumn format. RevTe
The viscosity of R32 and R125 at saturation
This paper reports new measurements of the viscosity of R32 and R125, in both the liquid and the vapor phase, over the temperature range 220 to 343 K near the saturation line. The measurements in both liquid and vapor phases have been carried out with a vibrating-wire viscometer calibrated with respect to standard reference values of viscosity. It is estimated that the uncertainty of the
present viscosity data is one of 0.5-1%, being limited partly by the accuracy of
the available density data. The experimental data have been represented by polynomial functions of temperature for the purposes of interpolation
Substantial Dose-response Relationship with Clinical Outcome for Lung Stereotactic Body Radiotherapy (SBRT) Delivered via Online Image Guidance
Purpose: To examine potential tumor dose-response relationships with various non-small cell lung cancer (NSCLC) SBRT fractionation regimens delivered with online CT-based image guidance.
American Society for Therapeutic Radiation Oncology (ASTRO) 52nd Annual Meeting October 31 - November 4, San Diego, C
Notes on the Third Law of Thermodynamics.I
We analyze some aspects of the third law of thermodynamics. We first review
both the entropic version (N) and the unattainability version (U) and the
relation occurring between them. Then, we heuristically interpret (N) as a
continuity boundary condition for thermodynamics at the boundary T=0 of the
thermodynamic domain. On a rigorous mathematical footing, we discuss the third
law both in Carath\'eodory's approach and in Gibbs' one. Carath\'eodory's
approach is fundamental in order to understand the nature of the surface T=0.
In fact, in this approach, under suitable mathematical conditions, T=0 appears
as a leaf of the foliation of the thermodynamic manifold associated with the
non-singular integrable Pfaffian form . Being a leaf, it cannot
intersect any other leaf const. of the foliation. We show that (N) is
equivalent to the requirement that T=0 is a leaf. In Gibbs' approach, the
peculiar nature of T=0 appears to be less evident because the existence of the
entropy is a postulate; nevertheless, it is still possible to conclude that the
lowest value of the entropy has to belong to the boundary of the convex set
where the function is defined.Comment: 29 pages, 2 figures; RevTex fil
Cardiac and Pulmonary Dosimetric Parameters in Lung Cancer Patients Undergoing Post-Operative Radiation Therapy in the Real-World Setting
Purpose/Objective(s): The recently published Lung ART trial reported increased rates of cardiac and pulmonary toxicity in the post-operative radiation therapy arm. It remains unknown whether the dosimetric parameters reported in Lung ART are representative of real-world practice. The purpose of this study is to examine heart and lung dose exposure in patients receiving post-operative radiation therapy for non-small cell lung cancer (NSCLC) across a statewide consortium.
Materials/Methods: From 2012 to 2020, 377 patients at 27 academic and community centers within the Michigan Radiation Oncology Quality Consortium (MROQC) underwent surgical resection followed by post-operative radiation therapy for non-metastatic NSCLC. Demographic and dosimetric data were prospectively collected for these patients. Rates of 3D-CRT and IMRT use were analyzed. Mean heart dose (MHD), heart V5, heart V35, mean lung dose (MLD), lung V20, target volume and minimum dose to 95% PTV were calculated for these patients and the reported dosimetric parameters were stratified by treatment modality.
Results: 51% of patients in this cohort had N2 disease at the time of surgery, 18% had a positive margin. 65.8% of patients were treated with IMRT compared to 32.1% treated with 3D-CRT. Average MHD for all patients was 10.3 Gy, mean Heart V5 was 40.3% and mean heart V35 was 12.6%. Average MLD was 11.2 Gy and mean lung V20 was 18.9%. These dosimetric parameters did not significantly differ based on treatment modality, with MHD and MLD 9.9 Gy and 10.1 Gy, respectively, for patients treated with 3D-CRT compared to 10.6 Gy and 11.8 Gy for patients treated with IMRT.
Conclusion: Cardiac and lung dosimetric parameters for patients receiving post-operative radiation therapy for NSCLC are similar to the dosimetric characteristics reported in Lung ART. The mean heart and mean lung doses observed are slightly lower (MHD 10.3 Gy, MLD 11.2 Gy) compared to Lung ART (MHD 13 Gy, MLD 13 Gy), possibly owing to increased use of IMRT. These data support application of Lung ART\u27s findings outside of the clinical trial setting
Shear Viscosity of a Hot Pion Gas
The shear viscosity of an interacting pion gas is studied using the Kubo
formalism as a microscopic description of thermal systems close to global
equilibrium. We implement the skeleton expansion in order to approximate the
retarded correlator of the viscous part of the energy-momentum tensor. After
exploring this in theory we show how the skeleton expansion can be
consistently applied to pions in chiral perturbation theory. The shear
viscosity is determined by the spectral width, or equivalently, the mean
free path of pions in the heat bath. We derive a new analytical result for the
mean free path which is well-conditioned for numerical evaluation and discuss
the temperature and pion-mass dependence of the mean free path and the shear
viscosity. The ratio of the interacting pion gas exceeds the lower
bound from AdS/CFT correspondence.Comment: 12 pages, 7 figures. Revision includes additional Appendix B. Matches
published versio
Higher heritabilities for gait components than for overall gait scores may improve mobility in ducks
International audienceAbstractBackgroundGenetic progress in selection for greater body mass and meat yield in poultry has been associated with an increase in gait problems which are detrimental to productivity and welfare. The incidence of suboptimal gait in breeding flocks is controlled through the use of a visual gait score, which is a subjective assessment of walking ability of each bird. The subjective nature of the visual gait score has led to concerns over its effectiveness in reducing the incidence of suboptimal gait in poultry through breeding. The aims of this study were to assess the reliability of the current visual gait scoring system in ducks and to develop a more objective method to select for better gait.ResultsExperienced gait scorers assessed short video clips of walking ducks to estimate the reliability of the current visual gait scoring system. Kendall’s coefficients of concordance between and within observers were estimated at 0.49 and 0.75, respectively. In order to develop a more objective scoring system, gait components were visually scored on more than 4000 pedigreed Pekin ducks and genetic parameters were estimated for these components. Gait components, which are a more objective measure, had heritabilities that were as good as, or better than, those of the overall visual gait score.ConclusionsMeasurement of gait components is simpler and therefore more objective than the standard visual gait score. The recording of gait components can potentially be automated, which may increase accuracy further and may improve heritability estimates. Genetic correlations were generally low, which suggests that it is possible to use gait components to select for an overall improvement in both economic traits and gait as part of a balanced breeding programme
Dynamics of fluctuations in a fluid below the onset of Rayleigh-B\'enard convection
We present experimental data and their theoretical interpretation for the
decay rates of temperature fluctuations in a thin layer of a fluid heated from
below and confined between parallel horizontal plates. The measurements were
made with the mean temperature of the layer corresponding to the critical
isochore of sulfur hexafluoride above but near the critical point where
fluctuations are exceptionally strong. They cover a wide range of temperature
gradients below the onset of Rayleigh-B\'enard convection, and span wave
numbers on both sides of the critical value for this onset. The decay rates
were determined from experimental shadowgraph images of the fluctuations at
several camera exposure times. We present a theoretical expression for an
exposure-time-dependent structure factor which is needed for the data analysis.
As the onset of convection is approached, the data reveal the critical
slowing-down associated with the bifurcation. Theoretical predictions for the
decay rates as a function of the wave number and temperature gradient are
presented and compared with the experimental data. Quantitative agreement is
obtained if allowance is made for some uncertainty in the small spacing between
the plates, and when an empirical estimate is employed for the influence of
symmetric deviations from the Oberbeck-Boussinesq approximation which are to be
expected in a fluid with its density at the mean temperature located on the
critical isochore.Comment: 13 pages, 10 figures, 52 reference
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