206 research outputs found

    Alternative AMTA and Loan Rate Options for Program Crops With Counter Cyclical Payments Triggered at the National and State Level

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    This analysis focuses on four policy options, based on national formulas where implications are examined for varying levels of loan rates and base AMTA payment rates.Agricultural and Food Policy,

    Evaluation of Alternative Base Periods for a National Counter Cyclical Payment Program for Rice, Upland Cotton, Corn, Wheat, Soybeans and Sorghum

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    A risk analysis of a national counter cyclical payment (CCP) program for six crops was completed for one year. National planted acre yield risk over the 1986-2000 period was used with FAPRI’s stochastic projection of crop prices for 2001 in the analysis. Four alternative base periods for triggering a CCP were evaluated. Three Added AMTA scenarios and a Base scenario of no additional market loss or CCP were also run for each of the crops.Agricultural and Food Policy,

    Analysis of Representative Rice Farms Under H.R. 2646 and the Continuation of the FAIR Act

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    In anticipation of the new farm bill, seventeen representative rice farms from six different rice-producing states have been analyzed to compare the continuation of the FAIR Act provisions with the House proposal, H.R. 2646. Each farm was simulated assuming each policy would be in place for the next five-year period, or 2002-2006. A full description of each of the farms can be found in the Appendix.Agribusiness, Agricultural and Food Policy, Crop Production/Industries,

    Adaptivity and a posteriori error control for bifurcation problems II: Incompressible fluid flow in open systems with Z_2 symmetry

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    In this article we consider the a posteriori error estimation and adaptive mesh refinement of discontinuous Galerkin finite element approximations of the bifurcation problem associated with the steady incompressible Navier-Stokes equations. Particular attention is given to the reliable error estimation of the critical Reynolds number at which a steady pitchfork or Hopf bifurcation occurs when the underlying physical system possesses reflectional or Z_2 symmetry. Here, computable a posteriori error bounds are derived based on employing the generalization of the standard Dual-Weighted-Residual approach, originally developed for the estimation of target functionals of the solution, to bifurcation problems. Numerical experiments highlighting the practical performance of the proposed a posteriori error indicator on adaptively refined computational meshes are presented

    Adaptivity and a posteriori error control for bifurcation problems II: Incompressible fluid flow in open systems with Z_2 symmetry

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    In this article we consider the a posteriori error estimation and adaptive mesh refinement of discontinuous Galerkin finite element approximations of the bifurcation problem associated with the steady incompressible Navier-Stokes equations. Particular attention is given to the reliable error estimation of the critical Reynolds number at which a steady pitchfork or Hopf bifurcation occurs when the underlying physical system possesses reflectional or Z_2 symmetry. Here, computable a posteriori error bounds are derived based on employing the generalization of the standard Dual-Weighted-Residual approach, originally developed for the estimation of target functionals of the solution, to bifurcation problems. Numerical experiments highlighting the practical performance of the proposed a posteriori error indicator on adaptively refined computational meshes are presented

    Receptor-Mediated Enhancement of Beta Adrenergic Drug Activity by Ascorbate In Vitro and In Vivo

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    RATIONALE: Previous in vitro research demonstrated that ascorbate enhances potency and duration of activity of agonists binding to alpha 1 adrenergic and histamine receptors. OBJECTIVES: Extending this work to beta 2 adrenergic systems in vitro and in vivo. METHODS: Ultraviolet spectroscopy was used to study ascorbate binding to adrenergic receptor preparations and peptides. Force transduction studies on acetylcholine-contracted trachealis preparations from pigs and guinea pigs measured the effect of ascorbate on relaxation due to submaximal doses of beta adrenergic agonists. The effect of inhaled albuterol with and without ascorbate was tested on horses with heaves and sheep with carbachol-induced bronchoconstriction. MEASUREMENTS: Binding constants for ascorbate binding to beta adrenergic receptor were derived from concentration-dependent spectral shifts. Dose- dependence curves were obtained for the relaxation of pre-contracted trachealis preparations due to beta agonists in the presence and absence of varied ascorbate. Tachyphylaxis and fade were also measured. Dose response curves were determined for the effect of albuterol plus-and-minus ascorbate on airway resistance in horses and sheep. MAIN RESULTS: Ascorbate binds to the beta 2 adrenergic receptor at physiological concentrations. The receptor recycles dehydroascorbate. Physiological and supra-physiological concentrations of ascorbate enhance submaximal epinephrine and isoproterenol relaxation of trachealis, producing a 3-10-fold increase in sensitivity, preventing tachyphylaxis, and reversing fade. In vivo, ascorbate improves albuterol's effect on heaves and produces a 10-fold enhancement of albuterol activity in "asthmatic" sheep. CONCLUSIONS: Ascorbate enhances beta-adrenergic activity via a novel receptor-mediated mechanism; increases potency and duration of beta adrenergic agonists effective in asthma and COPD; prevents tachyphylaxis; and reverses fade. These novel effects are probably caused by a novel mechanism involving phosphorylation of aminergic receptors and have clinical and drug-development applications
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