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141.
Gendrin A Mangold N Bibring JP Langevin Y Gondet B Poulet F Bonello G Quantin C Mustard J Arvidson R LeMouélic S 《Science (New York, N.Y.)》2005,307(5715):1587-1591
The OMEGA/Mars Express hyperspectral imager identified hydrated sulfates on light-toned layered terrains on Mars. Outcrops in Valles Marineris, Margaritifer Sinus, and Terra Meridiani show evidence for kieserite, gypsum, and polyhydrated sulfates. This identification has its basis in vibrational absorptions between 1.3 and 2.5 micrometers. These minerals constitute direct records of the past aqueous activity on Mars. 相似文献
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143.
Brigitte A. Kaufmann 《Agricultural Systems》2011,104(9):655-665
The notion that pastoralists are irrational managers due to strong adherence to tradition and culture is still common in livestock production sciences. Researchers and development practitioners tend to fall back on this notion when target groups do not adopt their proposed innovations without any obvious reason. It is however difficult to identify innovations that fit into resource-poor systems, and often this lack of fit is the reason why innovations are not taken up. Understanding why pastoralists do what they do, and learning about the constraints they face when regulating production processes, is a prerequisite for identifying viable improvement possibilities.This study focuses on understanding the reasoning behind pastoralists’ actions. The knowledge underlying pastoralists’ regulation of production processes is analysed with a method based on second-order cybernetics that offers insight in the system view of the actors in the system. It uses feedback and control principles of cybernetics to understand human control in human activity systems. For analysis purposes, a control loop model is proposed to systematically assess, for each management practice, the livestock keepers’ observations and the rules upon which they base their actions.This cybernetic knowledge analysis is illustrated using the example of milk offtake management in a pastoral camel production system in northern Kenya. The example is chosen because lack of knowledge on the complex milk offtake management led to the widespread preconception of poor pastoral management as the cause for high calf mortality.The cybernetic knowledge analysis reveals what livestock keepers consider as information in their production process, as well as the rules that inform their actions. The analysis enables to distinguish between management practices that serve as: (i) routine control; (ii) problem-solving control; or (iii) selection. This information is useful in transdisciplinary studies that involve local actors and other stakeholders in finding solutions to real-world problems. Through the proposed knowledge analysis methodology, scientists can learn about livestock keepers’ reasoning and problem-solving abilities, but also about aspects of the production processes where control is weak and new control possibilities are sought after. The analysis also yields information on how livestock keepers try to achieve their production goals despite restrictions and disturbances given by the production environment. This understanding is of high importance in low-external-input systems that have little scope to control production conditions but that do adapt to them. 相似文献
144.
Petit R Aguinagalde I de Beaulieu JL Bittkau C Brewer S Cheddadi R Ennos R Fineschi S Grivet D Lascoux M Mohanty A Müller-Starck G Demesure-Musch B Palmé A Martín JP Rendell S Vendramin GG 《Science (New York, N.Y.)》2003,300(5625):1563-1565
Glacial refuge areas are expected to harbor a large fraction of the intraspecific biodiversity of the temperate biota. To test this hypothesis, we studied chloroplast DNA variation in 22 widespread European trees and shrubs sampled in the same forests. Most species had genetically divergent populations in Mediterranean regions, especially those with low seed dispersal abilities. However, the genetically most diverse populations were not located in the south but at intermediate latitudes, a likely consequence of the admixture of divergent lineages colonizing the continent from separate refugia. 相似文献
145.
Schönbächler M Rehkämper M Halliday AN Lee DC Bourot-Denise M Zanda B Hattendorf B Günther D 《Science (New York, N.Y.)》2002,295(5560):1705-1708
Niobium-92 (92Nb) decays to zirconium-92 (92Zr) with a half-life of 36 million years and can be used to place constraints on the site of p-process nucleosynthesis and the timing of early solar system processes. Recent results have suggested that the initial 92Nb/93Nb of the solar system was high (>10(-3)). We report Nb-Zr internal isochrons for the ordinary chondrite Estacado (H6) and a clast of the mesosiderite Vaca Muerta, both of which define an initial 92Nb/93Nb ratio of approximately 10(-5). Therefore, the solar system appears to have started with a ratio of <3 x 10(-5), which implies that Earth's initial differentiation need not have been as protracted as recently suggested. 相似文献
146.
Renaud Tissier DVM PhD Sebastien Perrot PharmD PhD Brigitte Enriquez DVM PhD Dipl ECVPT 《Journal of Veterinary Cardiology》2005,7(1):53-58
Amlodipine is a dihydropyridine compound and belongs to the pharmacological family of calcium channel blockers. It is one of the main treatments of systemic arterial hypertension in cats and its validity has been confirmed in several reports. Its beneficial effect on the peripheral and coronary vascular bed is due to immediate vasodilation and to a delayed anti-hypertrophic action. The aim of the present review is to highlight the clinically-relevant characteristics of amlodipine, especially regarding its mechanism of action, and to present the main clinical reports supporting its interest in veterinary cardiology. 相似文献
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149.
The antiproliferative activity of 52 volatile compounds released from bacteria was investigated in agar diffusion assays against medically important microorganisms and mouse fibroblasts. Furthermore, the activity of these compounds to interfere with the quorum-sensing-systems was tested with two different reporter strains. While some of the compounds specific to certain bacteria showed some activity in the antiproliferative assay, the compounds common to many bacteria were mostly inactive. In contrast, some of these compounds were active in the quorum-sensing-tests. γ-Lactones showed a broad reactivity, while pyrazines seem to have only low intrinsic activity. A general discussion on the ecological importance of these findings is given. 相似文献
150.
Abundance of some skeletal muscle mitochondrial proteins is associated with increased blood serum insulin in bovine fetuses 总被引:1,自引:0,他引:1
Beata Pajak Patrycja Pawlikowska Isabelle Cassar-Malek Brigitte Picard Jean-Franois Hocquette Arkadiusz Orzechowski 《Research in veterinary science》2010,89(3):445-450
The aim of this study was to investigate the evolution of the abundance of cytochrome oxidase c subunit IV (NCOIV) and beta subunit of ATP synthase (β-ATP) during the last third of gestation in bovine skeletal muscles. Semitendinosus, longissimus thoracis and rectus abdominis muscles were chosen for the immunoblotting of the respective protein levels. Muscle and blood samples from bovine fetuses of randomly selected breeds were collected at 180, 210, and 260 days post-conception (dpc). The muscle tissue expressions of NCOIV, β-ATP were compared to blood glucose and insulin. At 260 dpc, protein levels of NCOIV raised in skeletal muscles. Additionally, β-ATP in semitendinosus and longissimus thoracis were elevated and paralleled by higher concentrations of blood serum insulin. It corroborates our previous observations indicating that accelerated metabolic differentiation of bovine skeletal muscles is associated with elevated blood insulin and occurs during the last trimester of gestation. Our observations point to the connection between insulin-sensitivity and the molecular mechanisms of mitochondrial contribution to ontogenesis of skeletal muscles. 相似文献