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Economic and social development indicators suggest that the small West African state of Sierra Leone is among the poorest
countries in the world. Sierra Leone’s economy and quality of life deteriorated rapidly during a decade of political instability
and civil war in the 1990s, when many people fled their homes and abandoned their livelihoods due to the rebel insurgency.
This paper examines the post-war reconstruction scenario in Sierra Leone and presents recent evidence from two rural communities
in the Eastern Province that were badly affected by the conflict. The paper considers the links between the farming and diamond
mining sectors, which, despite severe dislocation during the conflict period, have proved to be remarkably resilient. It is
argued that seasonal labour mobility associated with this dual economy has not only continued to be a key ingredient in sustaining
livelihood portfolios, but is actually an essential pre-condition for the creation of an enabling environment for sustainable
post-conflict return.
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Tony BinnsEmail: |
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南亚高压是亚洲夏季风系统的重要组成部分,它的强度及位置变化对亚洲夏季风降水有非常重要的影响,对其变化特征和物理机制的研究可以加深对亚洲夏季风演化的认识。论文利用一个海-气耦合模式(KCM),在轨道参数的强迫下模拟了全新世以来(9.5~0 ka B.P.)的气候变化,分析了全新世南亚高压的南北移动特征,并探讨其与亚洲夏季风降水的关系。研究发现,全新世以来南亚高压持续向南移动,同时也反映了对流层上层西风逐渐向南扩张,响应逐渐减少的夏季太阳辐射。早全新世南亚高压偏北主要是由于夏季太阳辐射增加导致伊朗高原感热加热加强。南亚高压的南北移动与亚洲夏季风降水有显著的关系,它与东亚季风区北部和印度季风区降水呈正相关关系,而与东亚季风区南部和西南季风区降水呈负相关关系。偏北的南亚高压在东亚北部上空产生异常反气旋,有利于对流层低层空气辐合上升,降水增加,此外异常反气旋还可以加强西太副高,使得输送到东亚北部的水汽增加。南亚高压偏北时还会在中低纬地区产生异常东风带,减弱了来自孟加拉湾的水汽输入,从而使得东亚南部和西南季风区降水减少。偏北的南亚高压还在阿拉伯海上空产生异常气旋,有利于印度夏季风降水的增加。南亚高压的南北振荡可以部分解释相同轨道强迫下亚洲夏季风降水出现显著空间差异的原因。
相似文献5.
Gondwanaland origin, dispersion, and accretion of East and Southeast Asian continental terranes 总被引:3,自引:0,他引:3
East and Southeast Asia is a complex assembly of allochthonous continental terranes, island arcs, accretionary complexes and small ocean basins. The boundaries between continental terranes are marked by major fault zones or by sutures recognized by the presence of ophiolites, mélanges and accretionary complexes. Stratigraphical, sedimentological, paleobiogeographical and paleomagnetic data suggest that all of the East and Southeast Asian continental terranes were derived directly or indirectly from the Iran-Himalaya-Australia margin of Gondwanaland. The evolution of the terranes is one of rifting from Gondwanaland, northwards drift and amalgamation/accretion to form present day East Asia. Three continental silvers were rifted from the northeast margin of Gondwanaland in the Silurian-Early Devonian (North China, South China, Indochina/East Malaya, Qamdo-Simao and Tarim terranes), Early-Middle Permian (Sibumasu, Lhasa and Qiangtang terranes) and Late Jurassic (West Burma terrane, Woyla terranes). The northwards drift of these terranes was effected by the opening and closing of three successive Tethys oceans, the Paleo-Tethys, Meso-Tethys and Ceno-Tethys. Terrane assembly took place between the Late Paleozoic and Cenozoic, but the precise timings of amalgamation and accretion are still contentious. Amalgamation of South China and Indochina/East Malaya occurred during the Early Carboniferous along the Song Ma Suture to form “Cathaysialand”. Cathaysialand, together with North China, formed a large continental region within the Paleotethys during the Late Carboniferous and Permian. Paleomagnetic data indicate that this continental region was in equatorial to low northern paleolatitudes which is consistent with the tropical Cathaysian flora developed on these terranes. The Tarim terrane (together with the Kunlun, Qaidam and Ala Shan terranes) accreted to Kazakhstan/Siberia in the Permian. This was followed by the suturing of Sibumasu and Qiangtang to Cathaysialand in the Late Permian-Early Triassic, largely closing the Paleo-Tethys. North and South China were amalgamated in the Late Triassic-Early Jurassic and finally welded to Laurasia around the same time. The Lhasa terrane accreted to the Sibumasu-Qiangtang terrane in the Late Jurassic and the Kurosegawa terrane of Japan, interpreted to be derived from Australian Gondwanaland, accreted to Japanese Eurasia, also in the Late Jurassic. The West Burma and Woyla terranes drifted northwards during the Late Jurassic and Early Cretaceous as the Ceno-Tethys opened and the Meso-Tethys was destroyed by subduction beneath Eurasia and were accreted to proto-Southeast Asia in the Early to Late Cretaceous. The Southwest Borneo and Semitau terranes amalgamated to each other and accreted to Indochina/East Malaya in the Late Cretaceous and the Hainanese terranes probably accreted to South China sometime in the Cretaceous. 相似文献
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南海张裂过程及其对晚中生代以来东南亚构造的启示——IODP建议书735-Full介绍 总被引:1,自引:1,他引:1
李春峰 汪品先 Dieter Franke 李家彪 许树坤 Peter Michael 周祖翼 翦知湣 李前裕 刘志飞 耿建华 木村学 阎贫 丘学林 王嘹亮 解习农 吴时国 吴能友 《地球科学进展》2009,24(12):1339-1351
南海的形成揭示了大陆边缘张裂和盆地形成的复杂模式,尽管已经进行了广泛研究,但是关于基底岩石和深海盆沉积层的精确年代数据还很缺乏,这使得对南海张裂年代的估计存在很大的误差,对张裂机制和历史的各种假设没有得到验证.同时只有对南海的张裂过程有了精确地分析与刻画,才能更好地理解西太平洋边缘海盆地的形成以及它们在印支块体受印度-欧亚板块碰撞而向东南挤出、青藏高原隆升中可能起到的作用.2009年正式提交的国际综合大洋钻探计划(IODP)建议书735-Full建议在南海深海盆内的4个站位上实施钻探.这4个站位分布在南海盆地4个不同的次级构造单元上(南海东北部、西北次海盆、东部次海盆和西南次海盆),这样的站位设计会确保完成本建议书的整体研究目标,即揭示南海的张裂历史和它对晚中生代以来东南亚构造的启示.位于南海盆地最东北部的站位有助于确定该区域地壳的属性和验证古南海是否存在,位于西北次海盆的站住可能会提供南海的最早张裂年代,另外2个分别位于东部次海盆和西南次海盆的站位将重点确定2个次海盆的绝对年龄、基底矿物成分与磁化率以及2个次海盆的相对张裂次序.这些站位的水深大约在2 910~4 400 m,钻探深度预计到海底以下大约700~2 200 m,总的钻透深度为5 959 m,其中5 359 m穿透沉积层,另外600 m或400 m钻入基底.所有这些站位的位置是由已有的地球物理观测数据所确定,目前计划收集更多的地质与地球物理数据以满足IODP对井位调查数据的要求. 相似文献
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Acta Geochimica - Asian dust has been identified in subtropical soils of China. Neodymium (Nd) and lead (Pb) elemental and isotopic geochemistry of soils in Southeast China were used to assess the... 相似文献
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Materializing post-colonial geographies: examining the textural landscapes of migration in the South Asian home 总被引:2,自引:0,他引:2
This paper considers the role of visual cultures in understanding the value of landscape to post-colonial migrants living in Britain. The paper also considers these visual cultures as prismatic devices which refract lived landscapes of South Asia and East Africa into British domestic scene. The visual cultures are investigated using a materialist lens. They are positioned as materials that allow embodied connections to landscapes experienced pre-migration, including sensory connections with past homes, natures and family life. These then become artefacts symbolising relationships with past landscapes, made meaningful in their presence in Britain homes. Using this materialist lens, visual cultures in the British Asian home, such as photographs, pictures, and paintings, are given meaning and value beyond their textual content. This paper is an exercise in reading visual cultures in the everyday through a materialist lens which allows for an examination of their place in the process of ‘making home' for South Asian women in Britain. In particular, objects presence the migratory experience of the South Asian community, importing ‘other' landscapes (previously shaped by colonial governance) into Britain, and help to shape environmental values, landscape imaginaries and South Asian landscapes of belonging in the post-colonial period. 相似文献
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Recent work on return migration in China suggests return migrants bring with them new knowledge, skills, and potentially beneficial relationships accumulated during their sojourns, enabling them to introduce new forms of leadership and community action. Social remittances of this kind could be read as carrying the potential to enhance collective action in support of sustainable local natural resource-based livelihoods. This study of the links between return migration, leadership and collective action in water management sounds a more cautionary note, demonstrating that home communities may respond to return migrants in ways that repeatedly mark and reiterate gender and kinship norms, reiterating gender, generational and clan-based social hierarchies. The paper draws on and contributes to recent feminist political ecology approaches to show how migrant returnees’ ’social remittances’ translate into leadership in collective action in a rural Chinese village in ways that reinforce existing gender hierarchies and social positions within the community, thus questioning the extent to which any influx of new ideas, relationships and practices acquired from migrant experiences necessarily destabilizes power and authority in the village in any meaningful way. 相似文献
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Groundwater has played an important role in economic development in Southeast Asian countries, but some problems caused by
nature or human actions such as contamination, over pumping, and land subsidence bring the necessity of more systematic groundwater
monitoring wells. The analytical hierarchy process with pairwise comparison was used to allocate and organize the regional
groundwater monitoring wells in five regions, Thailand, Cambodia, East/West Malaysia, and South Korea. Five different multi
criteria decision models, which were composed of three primary criteria and eight secondary criteria, were developed based
on the answers of the questionnaire from 76 groundwater experts in Thailand, 100 in Cambodia, 101 in East Malaysia, 87 in
West Malaysia, and 93 in South Korea. It was revealed that the weights of model criteria for each country, which also represent
relative importance on groundwater monitoring, were different according to the diverse groundwater situation. The most important
factor to determine the number of monitoring well was ‘number of households using only groundwater as a water source’ for
Thailand and South Korea, ‘number of contamination sources’ for Cambodia, ‘amount of groundwater use for drinking-water supply’
for East Malaysia, and ‘number of wells with contaminated water’ for West Malaysia. 相似文献
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We review the current knowledge about Southeast Asian volcanoes and their eruption histories, and focus on identifying tephrochronologic markers representing major explosive eruptions in order to further future palaeoclimate and volcanological studies. Forty-one volcanic edifices in Southeast Asia have been classified as large calderas by Whelley et al. (2015) and thus have, or are likely to have, produced large explosive eruptions with a Volcanic Explosivity Index (VEI) of 6–8. Unfortunately, only 20 such eruptions have known ages, spanning from 1.2 Ma to 1991 ad , and fewer have geochemical data that can be used for tephrostratigraphic correlations. Volcanic products from different geodynamic regions and different sources can generally be distinguished on major element plots (e.g. K2O versus CaO) of matrix glass composition. However, the distinction of multiple eruptions from the same source often requires additional data such as trace element compositions of matrix glass and/or mineral compositions. Biotite, but also magnetite compositions (MgO and TiO2 content in particular) appear to be very discriminating. Up to nine tuffs in addition to the three to four Toba tuffs can be utilised as widespread tephrochronologic markers and span a range from 1.2 to 1.6 Ma to recent. As only a few Holocene major eruptions have been well characterised and dated, many large calderas are still unstudied, and many distal tephra layers are still lacking a source, more tephrochronologic markers can certainly be defined in the future. 相似文献
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The relationship between plate tectonics and the reworking of continental crust remains controversial. Multistage, hornblende-free, S-type granites across the Malay Peninsula Sn belt are ideal for investigating this research question. Here we present zircon U-Pb ages, in-situ apatite Nd and zircon Hf isotope data, and whole-rock major and trace element data for these S-type granites and spatially associated dykes. Four generations of Permian–Triassic (276–272, 262–260, 231–222, and 202 Ma) S-type granites were identified. The different S-type granites show distinct in-situ zircon Hf and apatite Nd isotopic compositions, implying generation from different sedimentary protoliths. Input of mantle-derived components for the formation of all these S-type granites, further indicating that both continental crustal reworking and growth occurred in the Malay Peninsula during the Permian–Triassic. A 250 Ma dolerite dyke in the Eastern Province was derived from an E-MORB-like mantle source. However, a 202 Ma monzonite dyke in the Western Province, was derived from mafic magmas produced by the melting of enriched mantle, followed by subsequent incorporation of crustal materials. All these S-type granitic magmas were reduced that inherited from sedimentary protoliths, which were favourable for Sn mineralization. Apatite F-Cl concentrations and F/Cl ratios in the S-type granites and related dykes changed systematically through time. We infer that the formation of these S-type granites and related dykes corresponds to the Palaeo-Tethyan evolution (i.e., early subduction of Palaeo-Tethyan oceanic lithosphere and subsequent collision between the Sibumasu and Indochina blocks). Our study also support that multistage S-type granites can be generated in distinct tectonic environments at different times in the same region. 相似文献
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Fragments of basaltic and gabbroic rocks were obtained in cuttings from 15 exploration wells in the Na Sanun area of the Wichian Buri Sub-basin of the Phetchabun Basin in central Thailand. The samples represent flows and sills in lacustrine and fluvial sedimentary rocks of the Lower to mid-Miocene Wichian Buri Group. Mafic igneous units were identified in the sections based on their typically high-amplitude seismic reflections, confirmed by the examination of several hundred well cuttings and magnetic susceptibility measurements. Cross-sections of the sub-basin were constructed on the basis of previously published subsurface interpretations, seismic and well data, and petrological observations. Basaltic flows A, B, E, and F have ages of ca. 2 Ma, 16 Ma, 24 Ma and 18 Ma, based on inferred stratigraphic position. Gabbroic sill C and dioritic sill G are inferred to be correlative at ca. 11.6 Ma, and differ petrologically from ca. 12.8 Ma gabbroic sill D. Major minerals in both basaltic and gabbroic samples are plagioclase (ca. An50), anorthoclase, and augite, with pervasive alteration to Na- and Ca- zeolite minerals and analcime. Leucodioritic sill G also contains amphibole and high Ti-phlogopite. Overall, the rocks show within-plate tholeiitic to alkalic characteristics, and show similarities to basaltic surface outcrops of similar ages in the Wichian Buri-Lop Buri area. No evidence was seen in the subsurface for the andesitic to rhyolitic rocks of similar ages that occur at surface, but their presence cannot be precluded based on our limited data. 相似文献
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Bandana Purkayastha 《Geoforum》2005,36(2):181-196
The research on skilled international migration focuses primarily on the experiences of male migrants. Little work has been done on female migrants, especially those who migrated as dependents of highly skilled males. This paper presents some data on Asian Indian women in the US, and argues that these women suffer from cumulative disadvantage. The paper emphasizes that it is necessary to adopt a complex model involving the interaction of gendered/racialised immigration laws, workplace and household experiences in order to understand the experiences of these women. 相似文献
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Continuity and change in commuter partnerships: avoiding or postponing family migration 总被引:1,自引:0,他引:1
Marjolijn van der Klis 《GeoJournal》2008,71(4):233-247
While most people in post-industrial societies, such as The Netherlands, continue to live as nuclear families, new household
arrangements have emerged in which couples no longer commit to living in one shared residence. One such household arrangement
is the commuter partnership, in which one partner lives near work part of the time. The objective in this article was to gain
a better understanding of the sustainability of commuter partnerships and to contribute to uncovering the function that this
household arrangement can have in the coordination of parallel careers of different household members over time. The study
draws on in-depth interviews with both individual partners in 30 commuter partnerships with at least one residence located
in The Netherlands, and a follow-up survey of the same commuter couples several years later. Our findings indicate that, for
most couples, the commuter partnership should not be regarded as a prelude to family migration, but rather as a household
arrangement by which family migration is avoided altogether, either for a limited period, or as a long-term alternative to
the nuclear family. The findings further indicate that, when couples look on their commuter partnership as the result of their
individual choice, they generally envision the future duration of their commuter partnership quite accurately. When their
choice is guided by the external circumstances of job contracts, couples appear to be less accurate in predicting the future
duration of their commuter partnerships.
相似文献
Marjolijn van der KlisEmail: |
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本文围绕泰国沙蒙矿床锡成矿相关的中粗粒黑云母花岗岩及远离矿体的细粒角闪石黑云母花岗岩开展了全岩地球化学、锆石U-Pb年代学及原位Hf同位素研究。锆石U-Pb年龄显示两类花岗岩分别形成于210.9±1.1 Ma和206.5±1.0 Ma。二者均具有富碱(全碱含量为5.81%~8.22%)、弱过铝—强过铝(A/CNK=1.01~1.14)、相对富集Rb、Th、Pb等元素、低的TFeO/MgO(0.75~3.54)和10000Ga/Al(2.21~2.66)比值等特征。中粗粒黑云母花岗岩具有原生白云母,高的K2O/Na2O(1.56~2.50)和Rb/Sr(2.26~2.60)比值,且其锆石具有较高的P含量,属于典型的S型花岗岩。而细粒角闪石黑云母花岗岩普遍发育角闪石,具有低的K2O/Na2O(0.45~1.11)和Rb/Sr(0.54~1.18)比值,且其锆石具有较低的P含量,应属于典型的I型花岗岩。两种花岗岩具有截然不同的Hf同位素组成,其中中粗粒黑云母花岗岩具有明显低的εHf(... 相似文献
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Tatek Abebe 《Geoforum》2012,43(3):540-550
Many programmes for AIDS-affected children pursue resource-intensive and external interventions of care, and often place such children at the receiving end of the care continuum. The aim of this article is to explore from a socio-spatial perspective the capacities of families and children experiencing orphanhood and the policy significance of empowering both to address the growing challenge of orphan care in rural and urban Ethiopia. Drawing on participatory research (involving in-depth interviews, focus group discussions, story writing, photo essays, ranking, observation and household visits), the complex social dynamics of care and spatial diversities in the manifestations of the vulnerabilities, capacities, strengths, and potentials of children and their families are discussed. It is argued that rather than the lack of biological parents it is the combination of the absence of a carer and the presence of acute poverty and economic marginality that explain various forms of vulnerability in orphans and non-orphans. The article further argues that effective and sustainable care needs to be informed by identification and empowerment of ‘family collectives’ as sites of interventions. In doing so, it draws analytical attention to the importance of examining the socio-temporal processes of orphanhood and care, children’s changing circumstances, and family collectives’ variances in the capacity to provide support for them. Strategies for sustainable care should recognise the specific needs of AIDS-affected children and the resourceful ways in which they contribute to enhance the care-giving capacities of family collectives in the light of broader socio-cultural and political–economic contexts. 相似文献
18.
Land, ethnic, and gender change: Transnational migration and its effects on Guatemalan lives and landscapes 总被引:1,自引:0,他引:1
Migration to the United States of America from Guatemala effects many aspects of Guatemalan life. We document, through extensive ethnographic fieldwork, how migrants and their remittances effect gender relations, ethnicity, land use, and land distribution. Our evidence is drawn from research in four communities. San Pedro Pinula and Gualán represent communities of eastern Guatemala. San Cristóbal Totonicapán is an Indigenous town in Guatemala’s western highlands, and San Lucas is a lowland frontier community in the Guatemalan department of Ixcán, which borders Chiapas, Mexico. Our results reveal that migrants and their remittances, both social and tangible, result in significant changes in land use and land distribution in Ixcán. Migrant money permits the conversion of rainforest into cattle pasture and also results in the accumulation of land in the hands of migrants. In terms of land use, we see in San Pedro Pinula that migrant money also allows the Pokoman Maya to make small entries into the Ladino (non-indigenous) dominated cattle business. In San Pedro Pinula, the migration and return of Maya residents also permits them to slowly challenge ethnic roles that have developed over the last five centuries. When we look at how migration effects gender roles in Gualán and San Cristóbal we also note that migration and social remittances permit a gradual challenge and erosion of traditional gender roles in Guatemala. We point out, however, that migration-related changes to traditional gender and ethnic roles is gradual because migrants, despite their increased earnings and awareness, run into a social structure that resists rapid change. This is not the case when we examine land transformations in Ixcán. Here, migrants encounter few barriers when they attempt to put their new money and ideas to work. Despite the advantages that migration brings to many families, especially in the face of a faltering national economy and state inactivity regarding national development, we conclude that migration and remittances do not result in community or nation-wide development. At this stage migrant remittances are used for personal advancement and very little money and effort is invested in works that benefit communities or neighborhoods. We call for continued studies of the effects of international migration on Guatemalan hometowns that build on our initial studies to better understand the longer-term ramifications of migration in a country where no community is without migrants. 相似文献
19.
Dr. Elizabeth M. Thomas-Hope 《GeoJournal》1992,26(1):75-79
Human migration has contributed to the redistribution of diseases from regions where they were endemic, thereby creating new areas where the task of control and management has become necessary. This is the case with respect to the major haemoglobinopathies — sickle cell anaemia and thalassaemia — in the United Kingdom since World War II. On the one hand, the great cultural diversity of the immigrant population presents an important challenge in delivering health care to the populations at risk of the diseases. On the other hand, the spatial concentration of these populations is one of the greatest advantages in the management of the disorders, since access to centrally located services can be optimized.The case of health care relating to the major haemoglobinopathies in the United Kingdom raises practical and theoretical questions about the most effective health care delivery models for ethnic minority needs. In turn, this issue has important implications for decisions concerning national and regional budgetary priorities in the health service and the position of minority medicine in the allocation of resources. 相似文献
20.
Caroline Nagel 《Geoforum》2005,36(2):197-210
Migration scholars increasingly have turned their attention to skilled migration, focusing, in particular, on the transfer of professionals within and between transnational corporations. Recent efforts have been made to bring a `cultural' analysis to this phenomenon, including greater scrutiny of the corporate cultures and social networks in which skilled migrants are embedded. This research has emphasised the importance of locality even among these most footloose and transnational of migrants. But despite these complex views of skilled migration, analyses have generated a somewhat limited conception of `skilled migrants' as managerial elites disengaged from local life. This paper examines skilled migration from a different perspective. First, using the case of Arab immigrants in London, this paper highlights the complicated nature of migration trajectories and reveals the diversity of patterns and experiences within the category of skilled migrant. Second, focusing on responses from female study participants, this paper examines the ways in which skilled migrants, rather than disengaging themselves from the host society context, may participate in the local politics of multiculturalism and integration. 相似文献