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761.
Abstract The paper emphasizes the importance of communication for the success of technology sharing and information dissemination programs. The concept of the “gatekeeper”; is discussed and placed in the organizational perspective. Several characteristics by which this vital individual can be identified are delineated. The flow of information across and within organizations, communities and regions of interest is studied in the context of the gatekeeper, the liasion and the communication isolate—three groups of people identifiable within an organization. Information channels are next explored and a method of evaluating their effectiveness presented. The authors suggest that a technology sharing program needs to deal with certain distinct audiences termed politicians, managers, scientists, technologists and workers. Patterns of communication among these audiences together with a system of communicating with outside expertise needs to be analyzed at the outset of any extension or cooperative endeavor. This basic structure is then applied to a model indicating the role of a hypothetical International Sea Grant effort. The authors suggest that such an international program could best succeed when integrated with existing extension networks. Evaluation, feedback and follow‐up are mentioned as areas vital to the success of an extension or sharing program. The paper then proceeds to present some perspectives on communication and change agents and warns against the possible dangers which could plague an extension system. The authors conclude with some thoughts on an extension strategy. 相似文献
762.
Ruth Tallman 《Bioethics》2014,28(5):207-213
In this paper, I argue that the ‘modified youngest first’ principle provides a morally appropriate criterion for making decisions regarding the distribution of scarce medical resources, and that it is morally preferable to the simple ‘youngest first’ principle. Based on the complete lives system's goal of maximizing complete lives rather than individual life episodes, I argue that essential to the value we see in complete lives is the first person value attributed by the experiencer of that life. For a life to be ‘complete’ or ‘incomplete,’ the subject of that life must be able to understand the concept of a complete life, to have started goals and projects, and to know what it would be for that life to be complete. As the very young are not able to do this, it can reasonably be said that their characteristically human lives have not yet begun, giving those accepting a complete lives approach good reason to accept the modified youngest first principle over a simple ‘youngest first’ approach. 相似文献
763.
764.
One-carbon metabolism plays a critical role in both DNA methylation and DNA synthesis. Accumulating evidence has shown that interruptions of this pathway are associated with many disease outcomes including cardiovascular diseases and cancers. Mechanistic studies have been performed on genetic polymorphisms involved in one-carbon metabolism. However, expression profiles of these inter-related genes are not well-known. In this study, we examined the gene expression profiles of 11 one-carbon metabolizing genes by quantifying the mRNA level of the lymphocyte among 54 healthy individuals and explored the correlations of these genes. We found these genes were expressed in lymphocytes at moderate levels and showed significant inter-person variations, We also applied principle component analysis to explore potential patterns of expression. The components identified by the program agreed with existing knowledge about one-carbon metabolism. This study helps us better understand the biological functions of one-carbon metabolism. 相似文献
765.
Should attractive males have more sons? 总被引:5,自引:0,他引:5
It is often argued that females with attractive partners shouldproduce more sons because these sons will inherit their father'sattractiveness. Numerous field and laboratory studies have addressedthis hypothesis, with inconsistent results, but there is surprisinglylittle theoretical work on the topic. Here, we present an extensiveinvestigation of the link between male attractiveness and offspringsex ratios, using evolutionary, individual-based computer simulations.In situations where sexual selection leads to the stable exaggerationof a costly male trait and a costly female preference, we findthat females with attractive partners produce more sons thanfemales with unattractive partners. This same qualitative patternis seen for a wide range of different models, with discreteor continuous variation in the male trait, under Fisherian orgood-genes sexual selection and for abrupt or gradual sex ratioadjustment. However, in all simulations, it takes a huge numberof generations to evolve, suggesting that selection acting onsex ratio adjustment is weak. Our models ignore many potentialcosts and constraints associated with manipulation, which impliesthat selection may be weaker still in natural populations. Theseresults may explain why published evidence for sex ratio biasin relation to male attractiveness is mixed. 相似文献
766.
Apoptosis is one of the most basic biological processes. In apoptosis, tens of species are involved in many biochemical reactions with times scales of widely differing orders of magnitude. By the law of mass action, the process is mathematically described with a large and stiff system of ODEs (ordinary differential equations). The goal of this work is to simplify such systems of ODEs with the PEA (partial equilibrium approximation) method. In doing so, we propose a general framework of the PEA method together with some conditions, under which the PEA method can be justified rigorously. The main condition is the principle of detailed balance for fast reactions as a whole and the framework provides some meaningful physical insights of the full chemical kinetics. With the justified method as a tool, we simplify the Fas-signaling pathway model due to Hua et al. [6] under the empirical assumption that nine reactions therein can be well regarded as relatively fast. This paper reports our simplification, together with numerical results which confirm the reliability of both our simplified model and the empirical assumption. 相似文献
767.
768.
Fushan Shi Lifeng Yang Jihong Wang Mohammed Kouadir Yang Yang Yongyao Fu Xiangmei Zhou Xiaomin Yin Deming Zhao 《Acta biochimica et biophysica Sinica》2013,(11):973-978
The inflammatory responses in Alzheimer's disease and prion diseases are dominated by microglia activation. Three different phenotypes of microglial activation, namely classical activation, alternative activation, and acquired deactivation, have been described. In this study, we investigated the effect of amyloido- genic fragments of amyloid 13 and prion proteins (Aβ1_42 and PrP106-126) on various forms of microglial activation. We first examined the effect of Aβ1_42 and PrP106-126 stimulation on the mRNA expression levels of several markers of microglial activation, as well as the effect of cytochalasin D, a phagocytosis inhibitor, on microgllal activation in Aβ1_42- and PrP106-126- stimulated BV2 microglla. Results showed that Aβ1-42 and PrPlo6_126 induced the classical activation of BV2 microglia, decreased the expression level of alternative expression markers, and had no effect on the expression of acquired de- activation markers. Cytochalasin D treatment significantly reduced Aβ1_42- and PrP106-26-induced up-regulation of proinflammatory factors, but did not change the expression profile of the markers of alternative activation or acquired de- activation in BV2 cells which were exposed to Aβ1-42 and PrPlo6_126. Our results suggested that microglia interact with amyloidogenic peptides in the extraceilular milieu-stimulated microglial classical activation and reduce its alternative activa- tion, and that the uptake of amyloidogenic peptides from the extracellular milieu amplifies the classical microglial activation. 相似文献
769.
Bateman''s principle is not only used to explain sex differences in mating behaviour, but also to determine which sex has the greater opportunity for sexual selection. It predicts that the relationship between the number of mates and the number of offspring produced should be stronger for males than for females. Yet, it is unclear whether Bateman''s principle holds in cooperatively breeding systems where the strength of selection on traits used in intrasexual competition is high in both sexes. We tested Bateman''s principle in the cooperatively breeding superb starling (Lamprotornis superbus), finding that only females showed a significant, positive Bateman gradient. We also found that the opportunity for selection was on average higher in females, but that its strength and direction oscillated through time. These data are consistent with the hypothesis that sexual selection underlies the female trait elaboration observed in superb starlings and other cooperative breeders. Even though the Bateman gradient was steeper for females than for males, the year-to-year oscillation in the strength and direction of the opportunity for selection likely explains why cooperative breeders do not exhibit sexual role reversal. Thus, Bateman''s principle may not hold in cooperative breeders where both sexes appear to be under mutually strong sexual selection. 相似文献
770.
John S. Applegate 《人类与生态风险评估》2000,6(3):413-443
The precautionary principle, a familiar constituent of international and European environmental law, has only very recently entered the vocabulary of domestic environmental policy debates in the United States. The question naturally arises what role such a principle should play in American law. By breaking down statements of the precautionary principle into distinct ele ments, one can more readily find ways in which U.S. law reflects the precau tionary principle. This analysis reveals that American environmental law con tains precautionary elements and goals in many and varied settings, from the management of natural ecosystems, to pollution control standards, to risk assessment methodology. However, the precautionary approach appears in a highly diluted or compromised form. With rare exceptions, U.S. law balances precaution against other considerations, most importantly cost. Therefore, while precautionary elements are firmly entrenched in U.S. environmental law, it is more accurate to say that it reflects a precautionary preference rather than the precautionary principle. 相似文献