971 resultados para American Indian


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An ocean general circulation model (OGCM) is used to study the roles of equatorial waves and western boundary reflection in the seasonal circulation of the equatorial Indian Ocean. The western boundary reflection is defined as the total Kelvin waves leaving the western boundary, which include the reflection of the equatorial Rossby waves as well as the effects of alongshore winds, off-equatorial Rossby waves, and nonlinear processes near the western boundary. The evaluation of the reflection is based on a wave decomposition of the OGCM results and experiments with linear models. It is found that the alongshore winds along the east coast of Africa and the Rossby waves in the off-equatorial areas contribute significantly to the annual harmonics of the equatorial Kelvin waves at the western boundary. The semiannual harmonics of the Kelvin waves, on the other hand, originate primarily from a linear reflection of the equatorial Rossby waves. The dynamics of a dominant annual oscillation of sea level coexisting with the dominant semiannual oscillations of surface zonal currents in the central equatorial Indian Ocean are investigated. These sea level and zonal current patterns are found to be closely related to the linear reflections of the semiannual harmonics at the meridional boundaries. Because of the reflections, the second baroclinic mode resonates with the semiannual wind forcing; that is, the semiannual zonal currents carried by the reflected waves enhance the wind-forced currents at the central basin. Because of the different behavior of the zonal current and sea level during the reflections, the semiannual sea levels of the directly forced and reflected waves cancel each other significantly at the central basin. In the meantime, the annual harmonic of the sea level remains large, producing a dominant annual oscillation of sea level in the central equatorial Indian Ocean. The linear reflection causes the semiannual harmonics of the incoming and reflected sea levels to enhance each other at the meridional boundaries. In addition, the weak annual harmonics of sea level in the western basin, resulting from a combined effect of the western boundary reflection and the equatorial zonal wind forcing, facilitate the dominance by the semiannual harmonics near the western boundary despite the strong local wind forcing at the annual period. The Rossby waves are found to have a much larger contribution to the observed equatorial semiannual oscillations of surface zonal currents than the Kelvin waves. The westward progressive reversal of seasonal surface zonal currents along the equator in the observations is primarily due to the Rossby wave propagation.

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Previous research has defined the index of the Indian-Pacific thermodynamic anomaly joint mode (IPTAJM) and suggested that the winter IPTAJM has an important impact on summer rainfall over China. However, the possible causes for the interannual and decadal variability of the IPTAJM are still unclear. Therefore, this work investigates zonal displacements of both the western Pacific warm pool (WPWP) and the eastern Indian Ocean warm pool (EIOWP). The relationships between the WPWP and the EIOWP and the IPTAJM are each examined, and then the impacts of the zonal wind anomalies over the equatorial Pacific and Indian Oceans on the IPTAJM are studied. The WPWP eastern edge anomaly displays significant interannual and decadal variability and experienced a regime shift in about 1976 and 1998, whereas the EIOWP western edge exhibits only distinct interannual variability. The decadal variability of the IPTAJM may be mainly caused by both the zonal migration of the WPWP and the 850 hPa zonal wind anomaly over the central equatorial Pacific. On the other hand, the zonal migrations of both the WPWP and the EIOWP and the zonal wind anomalies over the central equatorial Pacific and the eastern equatorial Indian Ocean may be all responsible for the interannual variability of the IPTAJM.

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利用ERA40逐日再分析资料、NCEP/NCAR2逐日再分析资料、中国740个测站日降水资料、上海台风研究所提供的西太平洋热带气旋资料、Kaplan等重建的月平均SSTA资料、NOAA逐日长波辐射(OLR)等资料,应用离散功率谱分析、带通滤波、EOF分析等统计方法,研究了东亚夏季风(EASM)的移动特征、东亚地区季节内振荡(ISO)的基本特征、季节内振荡对东亚夏季风活动的影响、季节内振荡对东亚夏季风异常活动的影响机理。主要结论如下: (1)综合动力和热力因素定义了可动态描述东亚夏季风移动和强度的指数,并利用该指数研究了东亚夏季风的爆发和移动的季节内变化及其年际和年代际变化特征。研究发现,气候平均东亚夏季风前沿分别在28候、33候、36候、38候、40候、44候出现了明显的跳跃。东亚夏季风活动具有显著的年际变率,主要由于季风前沿在某些区域异常停滞和突然跨越北跳或南撤引起,造成中国东部旱涝灾害频繁发生。东亚夏季风的活动具有明显的年代际变化,在1965年、1980年、1994年发生了突变,造成中国东部降水由“南旱北涝”向“南涝北旱”的转变。 (2)东亚季风区季节内变化具有10~25d和30~60d两个波段的季节内振荡周期,以30-60d为主。存在三个主要低频模态,第一模态主要表征了EASM在长江中下游和华北地区活动期间的低频形势;第二模态印度洋-菲律宾由低频气旋式环流控制,主要表现了ISO在EASM爆发期间的低频形势;第三模态主要出现在EASM在华南和淮河活动期间的低频形势。第一模态和第三模态是代表东亚夏季风活动异常的主要低频形势。 (3)热带和副热带地区ISO总是沿垂直切变风的垂直方向传播。因此,在南海-菲律宾东北风垂直切变和副热带西太平洋北风垂直切变下,大气热源激发菲律宾附近交替出现的低频气旋和低频反气旋不断向西北传播,副热带西太平洋ISO以向西传播为主。中高纬度地区,乌拉尔山附近ISO以向东、向南移动或局地振荡为主;北太平洋中部ISO在某些情况下向南、向西传播。 (4)季风爆发期,伴随着热带东印度洋到菲律宾一系列低频气旋和低频反气旋, 冷空气向南输送,10~25天和30~60天季节内振荡低频气旋同时传入南海加快了南海夏季风的爆发。在气候态下,ISO活动表现的欧亚- 太平洋(EAP)以及太平洋-北美(PNA)低频波列分布特征(本文提出的EAP和PNA低频波列与传统意义上的二维定点相关得到的波列不同)。这种低频分布形式使得欧亚和太平洋中高纬度的槽、脊及太平洋副热带高压稳定、加强,东亚地区的低频波列则成为热带和中高纬度ISO相互作用影响东亚夏季风活动的纽带。不同的阶段表现不同的低频模态,30~60d低频模态的转变加快了EASM推进过程中跳跃性;30-60d低频模态的维持使得EASM前沿相对停滞。 (5)30-60d滤波场,菲律宾海域交替出现的低频气旋和低频反气旋不断向西北传播到南海-西太平洋一带。当南海-西太平洋地区低频气旋活跃时,季风槽加强、东伸,季风槽内热带气旋(TC)频数增加;当南海-西太平洋低频反气旋活跃时,季风槽减弱、西退,TC处于间歇期,生成位置不集中。 (6)在El Nino态下,大气季节内振荡偏弱,北传特征不明显,但ISO由中高纬度北太平洋中部向南和副热带西太平洋向西的传播特征显著,东亚地区ISO活动以第三模态为主,EASM集中停滞在华南和淮河流域,常伴随着持续性区域暴雨的出现,易造成华南和江淮流域洪涝灾害,长江和华北持续干旱。在La Nina态下,大气季节内振荡活跃,且具有明显的向北传播特征,PNA低频波列显著,东亚地区ISO活动以第一模态单峰为主;EASM主要停滞在长江中下游和华北地区,这些地区出现异常持续强降水,华南和淮河流域多干旱;在El Nino态向La Nina态转换期,ISO活动以第一模态双峰为主,长江中下游常常出现二度梅。

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This paper examines the effect of inbreeding level of population on the magnitude of inbreeding depression expressed by comparing them between two cultured populations (A and B) in the hermaphroditic animal of the bay scallop Argopecten irradians irradians. Population A is expected to have less genetic variations and higher inbreeding level due to longer cultured history (20 generations) and less "ancestral" individuals (26 individuals) than population B due to shorter cultured history (4 generations) and more "ancestral" individuals (406 individuals). Two groups within each population were produced, one using self-fertilization and one using mass-mating within the same population. Selfed offspring (AS and BS) from two populations both had lower fitness components than their mass-mated counterparts (AM and BM) and exhibited inbreeding depression for all examined traits, e.g. lower hatching, less viability and slower growth, indicating that inbreeding depression is a common feature in this animal. Fitness components in all traits of offspring from population A significantly differed those from population B and the magnitude of inbreeding depression for all traits in population A with higher inbreeding level was significantly smaller than that in population B with lower inbreeding level, indicating that both fitness components and magnitude of inbreeding depression were significantly affected by inbreeding level of populations and genetic load harbored in population A may be partially purged through inbreeding. Moreover, the magnitude of inbreeding depression in the two populations both varied among traits and life history stages. The present results support the partial-dominance hypothesis of inbreeding depression. (C) 2008 Elsevier B.V. All rights reserved.

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The presumed pair relationships of intercontinental vicariad species in the Podophyllum group (Sinopodophyllum hexandrum vs. Podophyllum pelatum and Diphylleia grayi vs. D. cymosa) were recently, considered to be paraphyletic. In the present paper, the trnL-F and ITS gene sequences of the representatives were used to examine the sister relationships of these two vicariad species. A heuristic parsimony analysis based on the trnLF data identified Diphylleia as the basal clade of the other three genera, but provided poor resolution of their inter-relationships. High sequence divergence was found in the ITS data. ITS1 region, more variable but parsimonyuninformative. has no phylogenetic value, Sequence divergence of the ITS2 region provided abundant, phylogenetically informative variable characters. Analysis of ITS2 sequences confirmeda sister relationship between the presumable vicariad species, in spite of a low bootstrap support for Sinopodophyllum hexandrum vs. Podophyllum pelatum. The combined ITS2 and trnL-F data enforced a sister relationship between Sinopodophyllum hexandrum and Podophyllum pelatum with an elevated bootstrap support of 100%. Based on molecular phylogeny, the morphological evolution of this group was discussed. The self-pollination might have evolved from cross-fertilization two times in this group. The different pollination and seed dispersal systems of Sinopodophyllum hexandrum and Podophlyllum pelatum resulted from their adaptations to different ecological habitats. The divergence time of Sinopodophyllum hexandrum-Podophyllum pelatum is estimated to be 6.52+/-1.89 myr based on the ITS divergence. The divergence of this species pair predated or co-occurred with the recent uplift of the Himalayas 4-3 myr during the late Miocene and the formation of the alpine habitats. Sinopodophyllum hexandrum developed a host of specialized characters in its subsequent adaptation to the arid alpine surroundings. The present study confirmed the different patterns of species relationship between Asian-North American disjuncts. The isolation of plant elements between North America and eastern Asia must have been a gradual process, resulting in the different phylogenetic patterns and divergence times of the disjuncts.

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This paper focuses on the analysis of the relationship between maritime trade and transport cost in Latin America. The analysis is based on disaggregated (SITC 5 digit level) trade data for intra Latin maritime trade routes over the period 1999-2004. The research contributes to the literature by disentangling the effects of transport costs on the range of traded goods (extensive margin) and the traded volumes of goods (intensive margin) of international trade in order to test some of the predictions of the trade theories that introduce firm heterogeneity in productivity, as well as fixed costs of exporting. Recent investigations show that spatial frictions (distance) reduce trade mainly by trimming the number of shipments and that most firms ship only to geographically proximate customers, instead of shipping to many destinations in quantities that decrease in distance. Our analyses confirm these findings and show that the opposite pattern is observed for ad-valorem freight rates that reduce aggregate trade values mainly by reducing the volume of imported goods (intensive margin).

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Vaughan, J. (2005). The Failure of American and British Propaganda in the Arab Middle East, 1945-1957: Unconquerable Minds. Basingstoke: Palgrave Macmillan. RAE2008

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Padget, Martin, 'Women in the West', In: 'The Making of the American West: People and Perspectives', (Santa Barbara, CA: ABC-Clio), pp.239-258, 2007 RAE2008

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Woods, Timothy, The Poetics of the Limit (New York: Palgrave Macmillan, 2003) RAE2008

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Padget, Martin, 'Travels in the American Southwest', Journal of the Southwest (2004) 44 (2) pp.413-440 RAE2008

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Forsyth, Alison, 'Re-defining the Dream on the American Stage', In: 'American Dreams: Dialogues in US Studies', Ricardo Miguez (ed), (Newcastle upon Tyne: Cambridge Scholars Press), pp.207-233, 2007 RAE2008

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O'Malley, T. (2007). Typically Anti-American?: The Labour movement, America and Broadcasting in Britain from Beveridge to Pilkington, 1949-62. In J. Wiener and M. Hampton (Eds.), Anglo- American Media Interactions,1850-2000 (pp.234-253). Basingstoke: Palgrave Macmillan. RAE2008

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The objective of this paper is to reassess the central factors which have shaped the Indian architecture. The author puts forward the concept of plurality introduced by Western art historians and argues that the diversity of the Indian architecture should not be explained in terms of religious differences, but in terms of the socio-economical situation in South Asia. He also elaborates on the Hindu caste system and its impact on the Indian architecture.

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The purpose of the project is to research the shape and influence of religion and spirituality in the lives of U.S. adolescents; to identify effective practices in the religious, moral, and social formation of the lives of youth; to describe the extent to which youth participate in and benefit from the programs and opportunities that religious communities are offering to their youth; and to foster an informed national discussion about the influence of religion in youth's lives, in order to encourage sustained reflection about and rethinking of our cultural and institutional practices with regard to youth and religion.