9,384 research outputs found

    Impacts from Government Regulations on the Canadian-U.S. Basis for Fed Cattle

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    Replaced with revised version of paper 09/01/09.Canada, Fed Cattle, Government Policy, International Trade, Prices, U.S., Livestock Production/Industries, Marketing, Q13, Q17, Q18,

    Trade-Related Policy and Canadian-U.S. Fed Cattle Transactions Basis

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    Price differences among fed cattle prices in Canada and the United States (referred to here as fed cattle basis) are important for Canadian cattle feeders, but changing government regulations in Canada and the United States have made basis more variable. This article uses transaction data from Canadian feedlots to quantify fed cattle price differentials in light of new policy initiatives. Using transaction prices, we find that differing slaughter regulations, labeling laws, and policies affecting access to U.S. markets for Canadian cattle affect fed cattle basis.basis, Canada, cattle prices, government policy, international trade, market access, transaction prices, International Relations/Trade, Livestock Production/Industries,

    COVID-19-Associated Cardiovascular Complications

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    Coronavirus disease 2019 (COVID-19) has been reported to cause cardiovascular complications such as myocardial injury, thromboembolic events, arrhythmia, and heart failure. Multiple mechanisms—some overlapping, notably the role of inflammation and IL-6—potentially underlie these complications. The reported cardiac injury may be a result of direct viral invasion of cardiomyocytes with consequent unopposed effects of angiotensin II, increased metabolic demand, immune activation, or microvascular dysfunction. Thromboembolic events have been widely reported in both the venous and arterial systems that have attracted intense interest in the underlying mechanisms. These could potentially be due to endothelial dysfunction secondary to direct viral invasion or inflammation. Additionally, thromboembolic events may also be a consequence of an attempt by the immune system to contain the infection through immunothrombosis and neutrophil extracellular traps. Cardiac arrhythmias have also been reported with a wide range of implicated contributory factors, ranging from direct viral myocardial injury, as well as other factors, including at-risk individuals with underlying inherited arrhythmia syndromes. Heart failure may also occur as a progression from cardiac injury, precipitation secondary to the initiation or withdrawal of certain drugs, or the accumulation of des-Arg9-bradykinin (DABK) with excessive induction of pro-inflammatory G protein coupled receptor B1 (BK1). The presenting cardiovascular symptoms include chest pain, dyspnoea, and palpitations. There is currently intense interest in vaccine-induced thrombosis and in the treatment of Long COVID since many patients who have survived COVID-19 describe persisting health problems. This review will summarise the proposed physiological mechanisms of COVID-19-associated cardiovascular complications

    Angle of Repose and Angle of Marginal Stability: Molecular Dyanmics of Granular Particles

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    We present an implementation of realistic static friction in molecular dynamics (MD) simulations of granular particles. In our model, to break contacts between two particles, one has to apply a finite amount of force, determined by the Coulomb criterion. Using a two dimensional model, we show that piles generated by avalanches have a {\it finite} angle of repose θR\theta_R (finite slopes). Furthermore, these piles are stable under tilting by an angle smaller than a non-zero tilting angle θT\theta_T, showing that θR\theta_R is different from the angle of marginal stability θMS\theta_{MS}, which is the maximum angle of stable piles. These measured angles are compared to a theoretical approximation. We also measure θMS\theta_{MS} by continuously adding particles on the top of a stable pile.Comment: 14 pages, Plain Te

    Gravitating σ\sigma Model Solitons

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    We study axially symmetric static solitons of O(3) nonlinear σ\sigma model coupled to (2+1)-dimensional anti-de Sitter gravity. The obtained solutions are not self-dual under static metric. The usual regular topological lump solution cannot form a black hole even though the scale of symmetry breaking is increased. There exist nontopological solitons of half integral winding in a given model, and the corresponding spacetimes involve charged Ban~\tilde nados-Teitelboim-Zanelli black holes without non-Abelian scalar hair.Comment: 35 pages, RevTe

    Analysis of Localization Phenomena in Weakly Interacting Disordered Lattice Gases

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    Disorder plays a crucial role in many systems particularly in solid state physics. However, the disorder in a particular system can usually not be chosen or controlled. We show that the unique control available for ultracold atomic gases may be used for the production and observation of disordered quantum degenerate gases. A detailed analysis of localization effects for two possible realizations of a disordered potential is presented. In a theoretical analysis clear localization effects are observed when a superlattice is used to provide a quasiperiodic disorder. The effects of localization are analyzed by investigating the superfluid fraction and the localization length within the system. The theoretical analysis in this paper paves a clear path for the future observation of Anderson-like localization in disordered quantum gases.Comment: 9 pages, 13 figure

    The social value of a QALY : raising the bar or barring the raise?

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    Background: Since the inception of the National Institute for Health and Clinical Excellence (NICE) in England, there have been questions about the empirical basis for the cost-per-QALY threshold used by NICE and whether QALYs gained by different beneficiaries of health care should be weighted equally. The Social Value of a QALY (SVQ) project, reported in this paper, was commissioned to address these two questions. The results of SVQ were released during a time of considerable debate about the NICE threshold, and authors with differing perspectives have drawn on the SVQ results to support their cases. As these discussions continue, and given the selective use of results by those involved, it is important, therefore, not only to present a summary overview of SVQ, but also for those who conducted the research to contribute to the debate as to its implications for NICE. Discussion: The issue of the threshold was addressed in two ways: first, by combining, via a set of models, the current UK Value of a Prevented Fatality (used in transport policy) with data on fatality age, life expectancy and age-related quality of life; and, second, via a survey designed to test the feasibility of combining respondents’ answers to willingness to pay and health state utility questions to arrive at values of a QALY. Modelling resulted in values of £10,000-£70,000 per QALY. Via survey research, most methods of aggregating the data resulted in values of a QALY of £18,000-£40,000, although others resulted in implausibly high values. An additional survey, addressing the issue of weighting QALYs, used two methods, one indicating that QALYs should not be weighted and the other that greater weight could be given to QALYs gained by some groups. Summary: Although we conducted only a feasibility study and a modelling exercise, neither present compelling evidence for moving the NICE threshold up or down. Some preliminary evidence would indicate it could be moved up for some types of QALY and down for others. While many members of the public appear to be open to the possibility of using somewhat different QALY weights for different groups of beneficiaries, we do not yet have any secure evidence base for introducing such a system

    Global Vortex and Black Cosmic String

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    We study global vortices coupled to (2+1) dimensional gravity with negative cosmological constant. We found nonsingular vortex solutions in ϕ4\phi^4-theory with a broken U(1) symmetry, of which the spacetimes do not involve physical curvature singularity. When the magnitude of negative cosmological constant is larger than a critical value at a given symmetry breaking scale, the spacetime structure is a regular hyperbola, however it becomes a charged black hole when the magnitude of cosmological constant is less than the critical value. We explain through duality transformation the reason why static global vortex which is electrically neutral forms black hole with electric charge. Under the present experimental bound of the cosmological constant, implications on cosmology as a straight black cosmic string is also discussed in comparison with global U(1) cosmic string in the spacetime of the zero cosmological constant.Comment: 35 pages, Late

    Variable Stars in the Cetus dSph Galaxy: Population Gradients and Connections with the Star Formation History

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    We investigate the variable star content of the isolated, Local Group, dwarf spheroidal galaxy (dSph) Cetus. Multi-epoch, wide-field images collected with the VLT/VIMOS camera allowed us to detect 638 variable stars (630 RR Lyrae stars and 8 Anomalous Cepheids), 475 of which are new detections. We present a full catalogue of periods, amplitudes, and mean magnitudes. Motivated by the recent discovery that the pulsational properties of the RR Lyrae stars in the Tucana dSph revealed the presence of a metallicity gradient within the oldest (>10 Gyr old) stellar populations, we investigated the possibility of an analogous effect in Cetus. We found that, despite the obvious radial gradient in the Horizontal Branch (HB) and Red Giant Branch (RGB) morphologies, both becoming bluer on average for increasing distance from the center of Cetus, the properties of the RR Lyrae stars are homogeneous within the investigated area (out to r~15'), with no significant evidence of a radial gradient. We discuss this in connection with the star formation history (SFH) previously derived for the two galaxies. The observed differences between these two systems show that even systems this small show a variety of early evolutionary histories. These differences could be due to different merger or accretion histories.Comment: Accepted for publication on MNRAS. The complete set of light curves and finding charts, together with the full table of the pulsational properties of all variable stars will be available in the on-line edition of the pape

    Light Curves and Period Changes of Type II Cepheids in the Globular Clusters M3 and M5

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    Light curves in the B, V, and I_c passbands have been obtained for the type II Cepheids V154 in M3 and V42 and V84 in M5. Alternating cycle behavior, similar to that seen among RV Tauri variables, is confirmed for V84. Old and new observations, spanning more than a century, show that V154 has increased in period while V42 has decreased in period. V84, on the other hand, has shown large, erratic changes in period that do not appear to reflect the long term evolution of V84 through the HR diagram.Comment: 28 pages, 12 figure
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