8,957 research outputs found

    10-04 "Buyer Power in U.S. Hog Markets: A Critical Review of the Literature"

    Get PDF
    The U.S. Departments of Justice and Agriculture have focused attention recently on rising levels of corporate concentration in agricultural markets and the challenges that may pose to U.S. anti-trust enforcement and agricultural policies. Both agencies have raised particular concerns about dominant firms’ exercise of buyer power over farmers, especially in livestock markets controlled by a shrinking number of large multinational meat packers. U.S. hog markets have undergone rapid concentration in the last 25 years, with the top four packers now controlling two-thirds of the market and Smithfield Foods, the industry leader, commanding 31 percent. Despite the rapid structural changes in the U.S. hog industry, the literature on buyer power in hog markets is quite limited. In this paper, we review the available literature, which has been generally presented as demonstrating that buyer power is not a significant problem. We find that interpretation to be poorly justified. Researchers have found well-documented evidence of market power on both the seller and the buyer sides of the market, though the studies have been less clear on the specific causes. Mirroring prevailing practices in Justice Department merger reviews, researchers have often discounted buyer power using methodologies more appropriate to seller power, then dismissed findings of seller power by pointing to offsetting “efficiency gains” from concentration. Yet such apparent efficiency gains in seller markets can include reductions in the prices concentrated firms pay for animals through their exercise of buyer power. We also raise the question of how buyer power in concentrated retail markets may compound the exercise of buyer power by packers. The paper concludes with a set of recommendations for further research, including the refinement of methodologies for the study of buyer power, and an assessment of proposed new USDA regulations on packer buying practices.

    Saturated hydrocarbon polymeric binder for advanced solid propellant and hybrid solid grains Quarterly report no. 2, 1 Feb. - 30 Apr. 1966

    Get PDF
    Synthesis and analysis of ethylene-neohexene copolymers with other non ketene-imine group free radicals for solid and hybrid grain propellant saturated hydrocarbon binder progra

    Criteria for the experimental observation of multi-dimensional optical solitons in saturable media

    Full text link
    Criteria for experimental observation of multi-dimensional optical solitons in media with saturable refractive nonlinearities are developed. The criteria are applied to actual material parameters (characterizing the cubic self-focusing and quintic self-defocusing nonlinearities, two-photon loss, and optical-damage threshold) for various glasses. This way, we identify operation windows for soliton formation in these glasses. It is found that two-photon absorption sets stringent limits on the windows. We conclude that, while a well-defined window of parameters exists for two-dimensional solitons (spatial or spatiotemporal), for their three-dimensional spatiotemporal counterparts such a window \emph{does not} exist, due to the nonlinear loss in glasses.Comment: 8 pages, to appear in Phys. Rev.

    The Detectability of AGN Cavities in Cooling-Flow Clusters

    Full text link
    Chandra X-ray Observatory has revealed X-ray cavities in many nearby cooling flow clusters. The cavities trace feedback from the central active galactic nulceus (AGN) on the intracluster medium (ICM), an important ingredient in stabilizing cooling flows and in the process of galaxy formation and evolution. But, the prevalence and duty cycle of such AGN outbursts is not well understood. To this end, we study how the cooling is balanced by the cavity heating for a complete sample of clusters (the Brightest 55 clusters of galaxies, hereafter B55). In the B55, we found 33 cooling flow clusters, 20 of which have detected X-ray bubbles in their ICM. Among the remaining 13, all except Ophiuchus could have significant cavity power yet remain undetected in existing images. This implies that the duty cycle of AGN outbursts with significant heating potential in cooling flow clusters is at least 60 % and could approach 100 %, but deeper data is required to constrain this further.Comment: 4 pages, 2 figures; to appear in the proceedings of "The Monsters' Fiery Breath", Madison, Wisconsin 1-5 June 2009, Eds. Sebastian Heinz & Eric Wilcots; added annotation to the figur

    Jet Interactions with the Hot Halos of Clusters and Galaxies

    Get PDF
    X-ray observations of cavities and shock fronts produced by jets streaming through hot halos have significantly advanced our understanding of the energetics and dynamics of extragalactic radio sources. Radio sources at the centers of clusters have dynamical ages between ten and several hundred million years. They liberate between 1E58-1E62 erg per outburst, which is enough energy to regulate cooling of hot halos from galaxies to the richest clusters. Jet power scales approximately with the radio synchrotron luminosity to the one half power. However, the synchrotron efficiency varies widely from nearly unity to one part in 10,000, such that relatively feeble radio source can have quasar-like mechanical power. The synchrotron ages of cluster radio sources are decoupled from their dynamical ages, which tend to be factors of several to orders of magnitude older. Magnetic fields and particles in the lobes tend to be out of equipartition. The lobes may be maintained by heavy particles (e.g., protons), low energy electrons, a hot, diffuse thermal gas, or possibly magnetic (Poynting) stresses. Sensitive X-ray images of shock fronts and cavities can be used to study the dynamics of extragalactic radio sources.Comment: 10 pages, 3 figures, invited review, "Extragalactic Jets: Theory and Observation from Radio to Gamma Ray, held in Girdwood, Alaska, U.S.A. 21-24 May, 2007, minor text changes; one added referenc

    AgRISTARS cropping practices and crop characteristics based on 1979 ESCS observations

    Get PDF
    There are no author-identified significant results in this report
    • …
    corecore