1000 resultados para 299.992


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Phosphate (Pi) availability is a major factor limiting growth, development, and productivity of plants. In both ecological and agricultural contexts, plants often grow in soils with low soluble phosphate content. Plants respond to this situation by a series of developmental and metabolic adaptations that are aimed at increasing the acquisition of this vital nutrient from the soil, as well as to sustain plant growth and survival. The development of a comprehensive understanding of how plants sense phosphate deficiency and coordinate the responses via signaling pathways has become of major interest, and a number of signaling players and networks have begun to surface for the regulation of the phosphate-deficiency response. In practice, application of such knowledge to improve plant Pi nutrition is hindered by complex cross-talks, which are emerging in the face of new data, such as the coordination of the phosphate-deficiency signaling networks with those involved with hormones, photo-assimilates (sugar), as well as with the homeostasis of other ions, such as iron. In this review, we focus on these cross-talks and on recent progress in discovering new signaling players involved in the Pi-starvation responses, such as proteins having SPX domains.

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Kirje 31.3.1967

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Kirje 16.12.1958

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Kirje 15.6.1942

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Kirje 28.4.1967

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How do organizations cope with extreme uncertainty? The existing literatureis divided on this issue: some argue that organizations deal best withuncertainty in the environment by reproducing it in the organization, whereasothers contend that the orga nization should be protected from theenvironment. In this paper we study the case of a Wall Street investment bankthat lost its entire office and trading technology in the terrorist attack ofSeptember 11 th. The traders survived, but were forced to relocate to amakeshift trading room in New Jersey. During the six months the traders spentoutside New York City, they had to deal with fears and insecurities insidethe company as well as outside it: anxiety about additional attacks,questions of professional identity, doubts about the future of the firm, andambiguities about the future re-location of the trading room. The firmovercame these uncertainties by protecting the traders identities and theirability to engage in sensemaking. The organization held together through aleadership style that managed ambiguities and created the conditions for newsolutions to emerge.

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Twelve regularly scheduled lettings and seven emergency/special lettings were held by the Iowa Department of Transportation for construction and maintenance work during the period covered by this report. At these lettings, projects totaling $492,299,871 were approved.

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Puhe

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Estudio complementario de la primera evaluación sobre los posibles efectos del represamiento del río Puyango - Tumbes. Los datos obtenidos confirman algunas modificaciones de orden limnológico - pesquero en el río y canales de marea, determinando la zona de Cazaderos como la más adecuada para el establecimiento del embalse. Se hace la expresa recomendación acerca del mínimo caudal del río, el cual puede ser similar al flujo de la estación seca. Indica las implicancias en los recursos acuáticos cultivables especialmente langostinos Penaeus.

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Acute myocardial dysfunction is a typical manifestation of septic shock. Experimentally, the administration of endotoxin [lipopolysacharride (LPS)] to laboratory animals is frequently used to study such dysfunction. However, a majority of studies used load-dependent indexes of cardiac function [including ejection fraction (EF) and maximal systolic pressure increment (dP/dt(max))], which do not directly explore cardiac inotropism. Therefore, we evaluated the direct effects of LPS on myocardial contractility, using left ventricular (LV) pressure-volume catheters in mice. Male BALB/c mice received an intraperitoneal injection of E. coli LPS (1, 5, 10, or 20 mg/kg). After 2, 6, or 20 h, cardiac function was analyzed in anesthetized, mechanically ventilated mice. All doses of LPS induced a significant drop in LV stroke volume and a trend toward reduced cardiac output after 6 h. Concomitantly, there was a significant decrease of LV preload (LV end-diastolic volume), with no apparent change in LV afterload (evaluated by effective arterial elastance and systemic vascular resistance). Load-dependent indexes of LV function were markedly reduced at 6 h, including EF, stroke work, and dP/dt(max). In contrast, there was no reduction of load-independent indexes of LV contractility, including end-systolic elastance (ejection phase measure of contractility) and the ratio dP/dt(max)/end-diastolic volume (isovolumic phase measure of contractility), the latter showing instead a significant increase after 6 h. All changes were transient, returning to baseline values after 20 h. Therefore, the alterations of cardiac function induced by LPS are entirely due to altered loading conditions, but not to reduced contractility, which may instead be slightly increased.