视觉人类学的理论视野

将视觉人类学"工具化"、"技术化"及研究对象的不同界定和对视觉研究理论的陌生,导致视觉人类学被"边缘化".视觉人类学的当代研究,不仅需要研究人类视觉文化遗物和通过镜像聚焦和折射的文化视像,还需要直接面对人类活态的视觉文化现象,面时不同群体的视觉表达、视觉传播和视觉行为,研究人类的群体性图像信息、视觉符号和视觉文化行为,关注视觉媒体和媒体革命对文化的影响,考察在现代视党媒体影响下的文化涵化、文化冲突和文化变迁.     

知识经济与甘肃人力资源的开发管理

本文在探讨知识经济时代人力资源开发与管理特点的基础上 ,从劳动力资源、人才资源等方面入手 ,分析了甘肃人力资源的现状 ,提出了我省应大力发展教育、注重素质培养 ,营造“尊重知识 ,尊重人才”的社会氛围 ,建立合理的人才资源流动、使用新机制等政策性建议     

浅议当前农村养老保障体系中的缺陷和问题

目前农村家庭养老矛盾重重 ,面临农村养老保障由家庭养老向社会养老逐渐过渡的问题。在统筹社会养老基金时 ,应考虑农村养老保障体制转换成本问题 ,应由集体经济和国家负担部分转换成本。家庭养老以精神激励为主 ,但也要实行有效的监督。社会养老基金统筹可采用浮动制的收费办法 ,以弥补保费收缴水平偏低的矛盾     

Effects of sterile insect releases on a population under predation or parasitism

Summary A continuous-time differential equation model was constructed which describes the population dynamics of a predator prey system in which sterile prey are released in a program designed to eradicate or reduce the prey population. It was found that the dynamics of the system behave quite differently when predators are present. Two conditions were found which have differing implications for the control program. If the predators still exist when the wild prey population declines to extinction, then the SIRM is assisted by the predators, sometimes to a considereble extent. If the predators decline to extinction before the wild prey population goes extinct, then the predators may or may not assist the SIRM depending on the parameters of the system. If the predators do assist the SIRM, then a potentially dangerous situation exists in which an explosion of the prey population could occur after the predators go extinct. Predator polyphagy would probably minimize this danger of an explosion since it would stabilize the predator population.     

Seasonal forcing on the dynamics ofClethrionomys rufocanus: Modeling geographic gradients in population dynamics

We interpret gradients in population dynamics of the gray-sided vole from the southwestern part of the island of Hokkaido to its northeastern part within the framework of a phenomenological model involving the relative length of summer and winter. In Hokkaido, as in other northern regions, both spring and fall is considered as short transition periods between the two main seasons — summer (the primary breeding season) and winter (the non-reproductive or secondary breeding season). We show that the geographic transition in dynamics may be understood as the combined consequence of different patterns of density-dependence during summer and winter, and geographically varying season lengths. Differences are shown to exist between summer and winter with respect to strength of density-dependence. Direct density-dependence, in particular, is stronger during winter than during summer. A model is presented to show how relative lengths of seasons can induce both stable and periodically fluctuating population dynamics. The results are compared and contrasted with what is otherwise known about the gradient in rodent dynamics in Fennoscandia.     

Hybridization and speciation in the carabid beetles of the subgenusOhomopterus (Coleoptera, Carabidae, genusCarabus)

Natural hybridization among wingless carabid beetles of the subgenusOhomopterus (Carabidae, genusCarabus) is reviewed, and its significance in the evolution of this subgenus discussed. Natural hybridization occurs between parapatric species of similar size. Two case studies of natural hybridization suggest that natural hybridization could have affected the evolution of this subgenus in different ways. When there is a large difference in genital morphology between hybridizing species, interspecific copulation often results in genital injuries that causes mortality of copulating individuals, and hence reduces the fitness of hybridizing individuals greatly. In such a case, hybridization may be effective in maintaining the parapatric distribution of the two species, and in the long term, may promote reinforcement selection for traits which are effective in prezygotic reproductive isolation. When the morphological difference in genitalia is not so large as to cause genital injury, a hybrid population may be established at the intermediate zone between two parental species, provided that the immigration rates of the two species into the intermediate zone are small. Thus, natural hybridization may have contributed to both divergence and reticulate evolution in this subgenus.     

Preference in flower visits and partitioning in pollen diets of stingless bees in an Asian tropical rain forest

Floral resource partitioning among stingless bees (Trigona, Meliponini, Apidae) in a lowland rain forest in Sarawak, Malaysia, was investigated using tree towers and walkways in a 4-year study that included a general flowering period. We obtained 100 collections of insect visitors to flowers of varying floral location and shape representing 81 plant species. The tendency of 11 species of stingless bees to visit specific flowers with a particular floral location and shape was analyzed by logistic regression analysis. This analysis showed that the proportion of flower visitor collections containing Trigona fuscobalteata and T. melanocephala differed according to floral location. The former was frequently collected at canopy and gap flowers, whereas the latter was most often collected at understory flowers. The analysis also suggested that T. erythrogastra was more rarely collected at shallow flowers than at deep flowers. Analysis of the pollen diets of T. collina, T. fuscobalteata, T. melanocephala, and T. melina revealed that similarity of pollen sources differed among the six permutated pairs of the four species. The lowest mean rank of similarity found was between T. fuscobalteata and T. melanocephala. This result supports the hypothesis that preference in visiting flowers in different locations leads to pollen resource partitioning. Received: May 14, 1997 / Accepted: April 23, 1999     

浅析免费报纸经营理念的变化

免费报纸是报业经营理念发展的产物,或许还不成熟,但至少有一点是不容置疑的,它顺应了当前竞争激烈的市场规律,顺应了新媒体、新技术不断出现和对纸媒体的冲击的现实,以读者为中心的靠扩大规模、尽可能地压低成本的经营理念,代表着办报的一种思路。