424 research outputs found
WHAT YOU SHOULD KNOW ABOUT HOG CHOLERA
I. WHAT IS HOG CHOLERA?
Hog cholera is a deadly, contagious disease that attacks swine only.
The disease is caused by hog cholera virus, an agent so small (1/250,000 of an inch) that it can even pass through a fine porcelain filter.
How do hogs act when they get the disease? They lie around hiding in their nest, have high fevers, are extremely weak and sick all over. They have little appetite, and often stand in a thinking attitude-motionless, tail relaxed, ears hanging limp, and the head slightly lowered as if in deep thought.
Very few hogs ever recover.
II. How IMPORTANT Is HOG CHOLERA?
Hog cholera is the most important disease of hogs in the United States today. Farmers lose millions of dollars worth of hogs from cholera each year. And the expense of annually vaccinating millions of hogs costs even more. Many foreign markets are closed to pork from the United States because of the fear of importing hog cholera.
The disease is important enough so that both state and federal governments have enacted regulatory measures and classed it as a reportable disease. In addition, the United States Congress has authorized the Secretary of Agriculture to enter into a marketing agreement with the hog cholera serum-virus industry. The original act was intended to provide that there should always be enough anti-hog cholera serum on hand to safeguard against sudden widespread outbreaks of the disease. Nevertheless, stocks of antiserum are being reduced every year
Environment-induced dynamical chaos
We examine the interplay of nonlinearity of a dynamical system and thermal
fluctuation of its environment in the ``physical limit'' of small damping and
slow diffusion in a semiclassical context and show that the trajectories of
c-number variables exhibit dynamical chaos due to the thermal fluctuations of
the bath.Comment: Revtex, 4 pages and 4 figure
Fluctuation-dissipation relationship in chaotic dynamics
We consider a general N-degree-of-freedom dissipative system which admits of
chaotic behaviour. Based on a Fokker-Planck description associated with the
dynamics we establish that the drift and the diffusion coefficients can be
related through a set of stochastic parameters which characterize the steady
state of the dynamical system in a way similar to fluctuation-dissipation
relation in non-equilibrium statistical mechanics. The proposed relationship is
verified by numerical experiments on a driven double well system.Comment: Revtex, 23 pages, 2 figure
A glassy contribution to the heat capacity of hcp He solids
We model the low-temperature specific heat of solid He in the hexagonal
closed packed structure by invoking two-level tunneling states in addition to
the usual phonon contribution of a Debye crystal for temperatures far below the
Debye temperature, . By introducing a cutoff energy in the
two-level tunneling density of states, we can describe the excess specific heat
observed in solid hcp He, as well as the low-temperature linear term in the
specific heat. Agreement is found with recent measurements of the temperature
behavior of both specific heat and pressure. These results suggest the presence
of a very small fraction, at the parts-per-million (ppm) level, of two-level
tunneling systems in solid He, irrespective of the existence of
supersolidity.Comment: 11 pages, 4 figure
Defects and glassy dynamics in solid He-4: Perspectives and current status
We review the anomalous behavior of solid He-4 at low temperatures with
particular attention to the role of structural defects present in solid. The
discussion centers around the possible role of two level systems and structural
glassy components for inducing the observed anomalies. We propose that the
origin of glassy behavior is due to the dynamics of defects like dislocations
formed in He-4. Within the developed framework of glassy components in a solid,
we give a summary of the results and predictions for the effects that cover the
mechanical, thermodynamic, viscoelastic, and electro-elastic contributions of
the glassy response of solid He-4. Our proposed glass model for solid He-4 has
several implications: (1) The anomalous properties of He-4 can be accounted for
by allowing defects to freeze out at lowest temperatures. The dynamics of solid
He-4 is governed by glasslike (glassy) relaxation processes and the
distribution of relaxation times varies significantly between different
torsional oscillator, shear modulus, and dielectric function experiments. (2)
Any defect freeze-out will be accompanied by thermodynamic signatures
consistent with entropy contributions from defects. It follows that such
entropy contribution is much smaller than the required superfluid fraction, yet
it is sufficient to account for excess entropy at lowest temperatures. (3) We
predict a Cole-Cole type relation between the real and imaginary part of the
response functions for rotational and planar shear that is occurring due to the
dynamics of defects. Similar results apply for other response functions. (4)
Using the framework of glassy dynamics, we predict low-frequency yet to be
measured electro-elastic features in defect rich He-4 crystals. These
predictions allow one to directly test the ideas and very presence of glassy
contributions in He-4.Comment: 33 pages, 13 figure
Sensitivity of HBT interferometry to the microscopic dynamics of freeze-out
We study the HBT interferometry of ultra-relativistic nuclear collisions
using a freezeout model in which free pions emerge in the course of the last
binary collisions in the hadron gas. We show that the HBT correlators of both
identical and non-identical pions change with respect to the case of
independent pion production. Practical consequences for the design of the event
generator with the built in Bose-Einstein correlations are discussed. We argue
that the scheme of inclusive measurement of the HBT correlation function does
not require the symmetrization of the multi-pion transition amplitudes
(wave-functions).Comment: 22 pages, 3 epsf figures, RevTe
Tunnelling defect nanoclusters in hcp 4He crystals: alternative to supersolidity
A simple model based on the concept of resonant tunnelling clusters of
lattice defects is used to explain the low temperature anomalies of hcp 4He
crystals (mass decoupling from a torsional oscillator, shear modulus anomaly,
dissipation peaks, heat capacity peak). Mass decoupling is a result of an
internal Josephson effect: mass supercurrent inside phase coherent tunnelling
clusters. Quantitative results are in reasonable agreement with experiments.Comment: 13 pages, 5 figure
Cardiovascular safety of celecoxib in acute myocardial infarction patients: a nested case-control study
The objective was to measure the impact of exposure to coxibs and non-steroidal antiinflammatory drugs (NSAID) on morbidity and mortality in older patients with acute myocardial infarction (AMI). A nested case-control study was carried out using an exhaustive population-based cohort of patients aged 66 years and older living in Quebec (Canada) who survived a hospitalization for AMI (ICD-9 410) between 1999 and 2002. The main variables were all-cause and cardiovascular (CV) death, subsequent hospital admission for AMI, and a composite end-point including recurrent AMI or CV death. Conditional logistic regressions were used to estimate the risk of mortality and morbidity. A total of 19,823 patients aged 66 years and older survived hospitalization for AMI in the province of Quebec between 1999 and 2002. After controlling for covariables, the risk of subsequent AMI and the risk of composite end-point were increased by the use of rofecoxib. The risk of subsequent AMI was particularly high for new rofecoxib users (HR 2.47, 95% CI 1.57–3.89). No increased risk was observed for celecoxib users. No increased risk of CV death was observed for patients exposed to coxibs or NSAIDs. Patients newly exposed to NSAIDs were at an increased risk of death (HR 2.22, 95% CI 1.30–3.77) and of composite end-point (HR 2.28, 95% CI 1.35–3.84). Users of rofecoxib and NSAIDs, but not celecoxib, were at an increased risk of recurrent AMI and of composite end-point. Surprisingly, no increased risk of CV death was observed. Further studies are needed to better understand these apparently contradictory results
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
We report a measurement of the longitudinal double-spin asymmetry A_LL and
the differential cross section for inclusive Pi0 production at midrapidity in
polarized proton collisions at sqrt(s) = 200 GeV. The cross section was
measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be
in good agreement with a next-to-leading order perturbative QCD calculation.
The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T <
11 GeV/c and excludes a maximal positive gluon polarization in the proton. The
mean transverse momentum fraction of Pi0's in their parent jets was found to be
around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC
- …