986 research outputs found

    Effects of Herbicide-Resistant Technology Fees on the Plant Population Decision for Cotton Production

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    This study evaluated effects on cotton net revenues of four herbicide-resistant technology policies used since 1996 by Monsanto. Results indicate that farmers may have an incentive to switch from narrow-row to wide-row cotton and to use a lower plant density when the technology fee is tied to the seeding rate.Farm Management,

    OPTIMAL PLANT POPULATION FOR ULTRA-NARROW-ROW COTTON PRODUCTION AS INFLUENCED BY LINT AND TRANSGENIC SEED PRICES

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    Farmers are concerned about the high costs of transgenic seed and technology fees associated with the large plant population densities recommended for ultra-narrow row cotton. This study evaluated the effects of alternative plant population density decision criteria on net revenues under different lint price and transgenic seed cost scenarios. Results indicate that farmers may be able to maximize profits by seeding for a target plant population density of approximately 15.5 plants m-2.Crop Production/Industries,

    Art Education at Bank Street College, Then and Now

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    Takes readers through the history of art education at Bank Street College to show the innovative and child-centered approaches that continue to challenge dominant educational thinking

    PROGRESS REPORT 1980-81 and WORK PLAN 1981-82

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    [Ca2+]i in human heart failure: a review and discussion of current areas of controversy.

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    Multiple abnormalities have been reported in the setting of human heart failure. It is unclear whether detected changes reflect adaptive alterations in myocardium subjected to increased and sustained hemodynamic overload or are pathogenic to the disease process. As a result of the observation that the primary defect in heart failure is decreased pump function, investigators have concentrated their efforts on determining systolic [Ca2+]i as a logical corollary and a causative mechanism for contractile dysfunction. A simple cause and effect relationship has therefore been proposed with regard to contractile dysfunction and [Ca2+]i. Yet some investigators have found no difference in peak systolic [Ca2+]i between failing and non-failing human myocardium, whereas others have found peak [Ca2+]i to be significantly reduced in failing hearts. Resting calcium concentrations have been reported either to be elevated in failing human myocardium or not different from non-failing human myocardium. Investigators should now appreciate that the force-calcium relationship is not a simple relationship. One must take into account the prolonged time course and slowed mobilization of [Ca2+]i as opposed to simply peak [Ca2+]i. When put in perspective of mechanisms and determinants of the Ca(2+)-force relationship, we begin to realize that failing human myocardium has the "potential" to generate normal levels of force. Only when stressed by [Ca2+]i overload and/or frequency perturbation does myocardium from patients with end-stage heart disease demonstrate contractile failure. Although [Ca2+]i availability and mobilization are likely to play a role in the systolic as well as diastolic dysfunction reported in human heart failure, it is likely that other mechanisms are involved as well (e.g., myocardial energetics). Myocardial energetics is directly related to [Ca2+]i and mobilization in failing human myocardium, because metabolites, e.g., ADP, inhibit pumps, such as sarcoplasmic reticulum Ca2+ ATPase activity. We therefore conclude that there is a role for intracellular calcium mobilization and myocardial energetics for systolic and diastolic dysfunction seen in human heart failure
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