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Formal models for service composition have been proposed with the variation of the requirements of service developers. Some famous models have provided checking and verification techniques and tools for the behavior of service composition. These models generally focus much on the message flow of web services and neglecting the data contained in the exchanged messages among services, which restrict the application range of these models and also the web service techniques. As new kind of services with different protocols and communication methods have appeared, it is needed to model service composition from a new view which is adapted to the new development in service area. In this paper we offer a function oriented model of service composition which treats the composite service as a software system and specify the function of services which can be directly used to the realization by service providers.  相似文献   
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The author articulates key stressors in the lives of families who are homeless. These stresses often combine with barriers such as lack of job opportunities and/or insensitive professionals. Strategies for helping homeless families overcome these barriers and related issues are presented.  相似文献   
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Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables.  相似文献   
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In five conditioned taste aversion experiments with rats, summation, retardation, and preference tests were used to assess the effects of extinguishing a conditioned saccharin aversion for three or nine trials. In Experiment 1, a summation test showed that saccharin aversion extinguished over nine trials reduced the aversion to a merely conditioned flavor (vinegar), whereas three saccharin extinction trials did not subsequently influence the vinegar aversion. Experiment 2 clarified that result, with unpaired controls equated on flavor exposure prior to testing; the results with those controls suggested that the flavor extinguished for nine trials produced generalization decrement during testing. In Experiment 3, the saccharin aversion reconditioned slowly after nine extinction trials, but not after three. Those results suggested the development of latent inhibition after more than three extinction trials. Preference tests comparing saccharin consumption with a concurrently available fluid (water in Experiment 4, saline in Experiment 5) showed that the preference for saccharin was greater after nine extinction trials than after three. However, saccharin preference after nine extinction trials was not greater, as compared with that for either latent inhibition controls (Experiments 4 and 5) or a control given equated exposures to saccharin and trained to drink saline at a high rate prior to testing (Experiment 5). Concerns about whether conditioned inhibition has been demonstrated in any flavor aversion procedure are discussed. Our findings help explain both successes and failures in demonstrating postextinction conditioned response recovery effects reported in the conditioned taste aversion literature, and they can be explained using a memory interference account.  相似文献   
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Much of the research on social interaction in mainstreamed settings has focused on “reverse mainstreamed” or special environments in contrast, the present study observed 600 social interactions in 19 regular preschools. Three findings emerged: a) retarded children are substantially integrated into the emotional and social life of the peer group, but not fully integrated into peer group verbal life; b) there is an inverse relationship between teachers’ initiation of social interaction with retarded children and the degree to which the latter are integrated into peer group life; and c) teachers provide retarded children with more verbal enrichment and emotional protection than these children receive from their peer group. On balance, these findings are fairly encouraging, suggesting that to a considerable extent mainstreaming is working in preschool classrooms.  相似文献   
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论文通过借鉴和辨析社会学理论中的冲突概念,对师生冲突概念作出界定。根据美国当代社会学家刘易斯·科塞的冲突分类理论,对学校师生冲突进行分类研究。在此基础上提出了三个观点:学校师生冲突的多数属于非现实性冲突;师生结构由紧密走向松散是师生冲突增多的重要原因;师生冲突具有一定的正面功能。  相似文献   
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Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion.  相似文献   
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