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221.
With the development of location technologies, advanced LBS-based ITS increasingly requires the capability of database technologies to manage the continuously arrived vehicles' location, traffic jam and other interrelated information of large amounts of traffic in the following years. And some burst arrival stream data will challenge the real-time performance and the allocation of limited resource. However, choosing a desirable database operator scheduling strategy can significantly improve the performance of the system. The path capability strategy was chosen and improved as ITS' operator scheduling strategy to meet the real-time response and the minimal memory requirement of the system.  相似文献   
222.
This essay considers the development of the nuclear science programme in Malaysia from a transnational perspective by examining the interactions between state agents and other external nuclear-knowledge/technology related actors and agents. Going beyond the model of knowledge diffusion that brings together concerns articulated in Harris’s (2011) geographies of long distance knowledge and Reinhardt's (2011) role of the expert in knowledge transfer, the proposed three-phase model of knowledge transfer theorises the pathways undertaken by a late-blooming participant of modern science and technology as the latter moves from epistemic dependency to increasing independence despite the hurdles encountered, and the underdevelopment of many areas of its technoscientific economy. The model considers tensions stemming from the pressures of expediency for meeting national developmental goals on the one side, and the call to support the objectives of basic science on the other. The three phases of the model are epistemic transition, epistemic transplantation and localisation, and epistemic generation (ETTLG). As additional support for the proposed model, three arguments are proffered as deeper explanations of the epistemic goal by using Malaysia as a case study: knowledge transfer for political legitimization, knowledge transfer for countering agnotology, and knowledge transfer for social engineering and science diplomacy.  相似文献   
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224.
Isocapnia mogila , a rare winter stonefly, is found in good numbers in Humboldt County, California. In the 50 years since this species was described, very few specimens were recorded from only 4 sites in California and Oregon. Emergence seems to be higher in the fall and early winter than in the late winter and spring.  相似文献   
225.
Genetic variation within populations reflects population-level social and demographic processes and influences how a population behaves as an evolutionary unit. We examined partitioning of genetic variation in striped skunks ( Mephitis mephitis ) from the Southern High Plains of Texas during 1994-1995. Sixty-nine male and 35 female skunks were sampled on four 12.8-km 2 study plots. Plot centers ranged from 17.6 to 61.6 km apart. We used multi-locus DNA fingerprinting with 2 probes, pV47 and CTTxAGG, to test 3 hypotheses: (1) females are more genetically similar to other females than males are to other males on the same plot (indicating greater female philopatry than male philopatry), (2) genetic similarity is greater within plots than among plots (indicating partitioning of genetic variation in space), and (3) genetic similarity of males decreases as the distance separating males increases (indicating geographic distance affects rates of gene flow). In general, males on a plot had lower average genetic similarity than females. Genetic similarity within plots was not different from genetic similarity among plots for males or for females. Genetic similarity of males did not decrease with increasing distance among plots. The lack of geographical genetic structure in striped skunks suggests at the scale of this study (< 60 km) that gene flow of biparentally inherited genes is not distance-mediated. However, the higher similarity values for females than for males on the same plot supports an effect of male-biased dispersal and female philopatry on partitioning of genetic variation between sexes.  相似文献   
226.
Five implications of a biogeographic model of pygmy rabbits ( Brachylagus idahoensis ) in eastern Washington proposed in 1991 are confirmed by 11 new late-Quaternary records. Pygmy rabbits from eastern Oregon colonized eastern Washington during the late Pleistocene and occupied their largest range during the middle and late Holocene. Disjunction of the eastern Washington population from that in eastern Oregon occurred during at least the late Holocene. Nineteenth-century cattle grazing and 20th-century agricultural practices reduced habitat preferred by pygmy rabbits. Conservation of the small remaining population of pygmy rabbits will necessitate altered land use practices.  相似文献   
227.
In order to elucidate the genetic diversity and taxonomic status of Siberian roe deer (Capreolus pygar- gus) from the Korean peninsula, partial sequences of the mitochondrial cytochrome b gene were analyzed. We col- lected 57 roe deer samples from Mainland and Jeju Island between July 2004 and June 2009. A total of 50 sequences (1,070 bp) were obtained, and seven haplotypes were defined. Five haplotypes were found from Mainland, and two were discovered from Jeju Island. The genetic diver- sity was lower in the Jeju Island population than in the Mainland population. In addition, both the consensus neighbor-joining tree and maximum parsimony tree showed an identical topology between the Mainland and Jeju Island clades. Based on the results, two subspecies of the Korean roe deer were confirmed. Siberian roe deer in Jeju Island showed a distinct difference in the cytochrome b gene compared with other Siberian roe deer, being aunique native species inhabiting only Jeju Island in Korea. Because Siberian roe deer in Jeju Island can be classified at subspecies level, the new subspecies in Jeju was named Capreolus pygargus jejuensis in this study. For this new subspecies, reasonable conservation and management effort is needed in the future.  相似文献   
228.
229.
Regulation of cell movement is mediated by stretch-activated calcium channels.   总被引:10,自引:0,他引:10  
J Lee  A Ishihara  G Oxford  B Johnson  K Jacobson 《Nature》1999,400(6742):382-386
Intracellular calcium regulates many of the molecular processes that are essential for cell movement. It is required for the production of actomyosin-based contractile forces, the regulation of the structure and dynamics of the actin cytoskeletons, and the formation and disassembly of cell-substratum adhesions. Calcium also serves as a second messenger in many biochemical signal-transduction pathways. However, despite the pivotal role of calcium in motile processes, it is not clear how calcium regulates overall cell movement. Here we show that transient increases in intracellular calcium, [Ca2+]i, during the locomotion of fish epithelial keratocytes, occur more frequently in cells that become temporarily 'stuck' to the substratum or when subjected to mechanical stretching. We find that calcium transients arise from the activation of stretch-activated calcium channels, which triggers an influx of extracellular calcium. In addition, the subsequent increase in [Ca2+]i is involved in detachment of the rear cell margin. Thus, we have defined a mechanism by which cells can detect and transduce mechanical forces into biochemical signals that can modulate locomotion.  相似文献   
230.
M Lee  G S Myers 《Experientia》1979,35(6):824-825
During protein-energy malnutrition appositional bone growth in the seventh caudal vertebra of the rat slows and finally ceases. During rehabilitation appositional growth begins agains and attains a rate in excess of that of the controls. This may account for alterations in skeletal proportions resulting from malnutrition.  相似文献   
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