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51.
    
Expanded border enforcement has made unauthorised migration to the US more risky, costly, and prone to failure. Research on the material consequences of border enforcement for migrant‐sending households in Central America reveals that the economic hardships enforcement exacts on migrants at times diminishes enforcement's desired deterrent power. Heightened risks have driven up the cost of migration and pushed many to fund their trips through loans. Consequently, migrant detention, deportation, or death can result in poverty and privation for indebted households and the seizure of loan collateral, typically homes and land, in turn prompting crises in household reproduction. With a US wage the most viable means to ameliorate economic hardships, enforcement outcomes push some to return migration. Our findings suggest that US border enforcement efforts at times perpetuate the very unauthorised migration they seek to impede, while also helping to reproduce the border itself by deepening the marginalisation that drives migration decisions.  相似文献   
52.
The microstructures and chemical compositions of some 55 Egyptian blue and green frit samples from New Kingdom Egypt and 15th century BC Mesopotamia are determined using analytical scanning electron microscopy, the main focus being on frit cakes, powder residues, and frit vessel and bead fragments from one of the “factory areas” at Amarna in Middle Egypt. Replicate Egyptian blue frits produced in the laboratory are similarly investigated. Comparison of the microstructures of the ancient and replicate samples suggest that frit cakes are the primary product, and that these were ground to produce the powder, and then moulded to shape and refired to produce the vessels and beads. Egyptian blue and green frits are shown to be distinct pigments, the pigment produced depending on the relative proportions of copper oxide and lime in the mixtures. The bulk and glass phase compositions are used to try to infer the different sources of the quartz, lime, copper and alkali flux used in the production of frits from Egypt and Mesopotamia. An estimate is made of the scale of production of Egyptian blue frit in New Kingdom Egypt.  相似文献   
53.
尚义 《攀登》2008,27(5):25-26
30年改革开放是坚持群众路线的生动体现,即“一切为了群众,一切依靠群众”是改革开放的根本出发点和落脚点;“从群众中来,到群众中去”是改革开放的重要保证。由此可见,改革开放和坚持群众路线是有机的统一体。  相似文献   
54.
王晓德 《史学集刊》2008,1(1):77-83
在20世纪期间,源于美国的现代大众消费文化对其他国家的发展产生了巨大影响,法国便是其中比较有代表性的国家.第二次世界大战之后,美国大众文化在法国得到了更为广泛的传播,促使法国人消费理念的变化,成为法国大踏步地迈入现代大众消费社会的主要原因之一.然而法国传统的生活方式并没有因为进入现代大众消费社会而发生本质上的变化,只不过是多了些现代生活的气息而已.  相似文献   
55.
Various ethnographic sources have demonstrated the symbolic and ritualistic importance of psychoactive plants in Native American societies. The social milieu of these mind- altering plants appears to be ancient. Archaeological evidence during the Tiwanaku empire expansion along the Atacama Desert of Chile, circa 500–1000 A.D., shows the presence of highly decorated snuffing tablets and tubes as grave goods. The preservation of mummified human bodies in the Azapa Valley, northern Chile, provided an opportunity to test the exact nature of the psychoactive plants used in this region. Using gas chromatography/mass spectrometry (GC–MS), here we show that ancient Andean populations from northern Chile consumed Banisteriopsis, a vine that contains harmine. This is the first direct archaeological evidence of hallucinogenic and medicinal ethnographic practices. Interestingly enough, this rainforest plant does not grow along the Atacama coast, thus our findings suggest extensive plant trade networks in antiquity as far as the Amazon.  相似文献   
56.
Two American geographers comment on the preceding analysis of restructuring of Beijing's social space (Feng et al., 2007) by presenting observations on the city's Olympic Games, forthcoming in the summer of 2008. The authors focus on some of the more salient geographical impacts stemming from construction, relocation, and related measures undertaken by the authorities to accommodate the event. Included in the paper are sections on environmental concerns (particularly air pollution), infrastructure (water supply, automobile traffic, and mass transit), and relocation and displacement of residents (particularly of migrants and other disadvantaged segments of the population). Journal of Economic Literature, Classification Numbers: I31, O15, O18, P20. 2 figures, 2 tables, 44 references.  相似文献   
57.
Evidence for bitumen use in Middle Palaeolithic sites is an exception in Pleistocene archaeology. This paper presents the discovery of three tar-bearing Levallois artefacts found in the Mousterian sequence in Hummal (Central Syria). The organic residues were submitted to geochemical study. Gas chromatography–mass spectrometry analyses of saturated and aromatic hydrocarbons and isotopic data show the presence of bitumen. The most likely location of natural asphalt provisioning is the Shaaf outcrop in the Bichri desert. The bitumen-bearing stone tools add further important data to the growing knowledge about bitumen processing in the Middle Palaeolithic spring sites of El Kowm. Identification of the provisioning place for natural asphalt enables a more precise assumption about the site's catchment area. From a technological point of view, the tar-bearing specimens provide information on the range of tool forms selected for hafting. Ballistic features arguably indicate that the pointed Levallois blanks seem to be spear points that were fitted to a wooden handle. In at least one case, this technical procedure was seemingly executed during a brief episode of occupation and replacement of worn out implements. This small, bracketed window of detailed insight into Mousterian technology is linked with the more general relationship between Levallois technology and stone tool hafting.  相似文献   
58.
It has become commonplace to talk about humans hunting mammoths, and overhunting is thought to have been one of the causes of the mammoth extinction. However, definite evidence of mammoth kills by humans remains surprisingly scarce. Here we show convincing evidence of mammoth hunting in the Siberian Arctic between 29 000 and 27 000 14C years BP. Our data set, from the Yana Upper Palaeolithic site (Siberian Arctic), includes the following: fragments of lithic points and ivory shaft embedded in two mammoth scapulae; two identical holes made by projectiles in a mammoth scapula and a pelvic bone; mammoth tongue bones found in the cultural layer far away from the main mammoth bone accumulation, indicating the consumption of fresh mammoth meat; and a narrow mammoth bone size distribution, implying hunting selection based on animal size. The data suggest that Palaeolithic Yana humans hunted mammoths sporadically, presumably when ivory was needed for making tools. Such non-intensive hunting practiced by humans over millennia would not be fatal to a sustainable mammoth population.  相似文献   
59.
便携式X射线荧光光谱仪作为快捷的无损分析技术,广泛应用于壁画文物的现场分析中.本文利用便携式X射线荧光光谱仪分析了西藏拉萨大昭寺转经廊壁画,选取部分样品,利用实验室X射线荧光分析,发现所分析颜料的主要显色元素具有一致性,并利用拉曼光谱确定了壁画颜料的成分.通过比较研究,发现便携式X射线荧光光谱仪可确定大部分色彩较为纯正的颜料的成分,同时,由于西藏拉萨大昭寺壁画颜料的杂多性,对于含砷的橙色颜料、含砷或含铅与含铁的黄色颜料、含铜砷的绿色颜料、含钙硫的白色颜料、群青与孔雀石的混合颜料则需结合拉曼光谱确定之.本研究工作显示,利用便携式X射线荧光光谱仪开展现场检测,可极大地减少实验室分析样品的取样数量,有利于壁画颜料的无损分析与微损分析.  相似文献   
60.
和东红 《攀登》2006,25(3):89-91
本文通过阐述现阶段利益群体多元化矛盾现状、特点,分析了利益群体多元化矛盾的性质和化解利益群体多元化矛盾的意义,提出了化解利益群体多元化矛盾的基本思路。  相似文献   
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