Structure of the Potential Vorticity of an Explosive Cyclone over the Eastern Asian Region in Late November 2013

An explosive extratropical cyclone(EC)over the Eastern Asian region that caused two shipwrecks is analyzed using ERA-Interim reanalysis data from the European Center for Medium-Range Weather Forecasts.Analyses of the evolution of the EC reveal that the positive potential vorticity(PV)at the upper-tropospheric level displays a hook-shaped structure during the mature period of the cyclone.The PV distribution forms a vertically coherent PV structure called a PV tower.The vertical distribution of the PV can induce and strengthen cyclonic circulation from the lower-to upper-levels of troposphere,which is an important deepening mechanism of explosive cyclone.The PV tower occurs approximately ten hours prior to the development of surface occlusion in the cyclone.The evolution of surface fronts closely follows the development of the horizontal upper-tropospheric PV.This tandem development is largely attributed to the ability of the positive upper-tropospheric PV and the PV tower to induce cyclonic circulation simultaneously.The kinematic wrap-up process of cyclonic circulation also accelerates the formation of warm occlusion.A conceptual model of the distributions of positive PV and potential temperature combining the perspectives of dynamic tropopause folding,PV tower,and atmospheric stability,including westward tilting and baroclinicity,is proposed.This model can illustrate the explosive deepening mechanism of ECs.The regions of convective instability and rainfall determined by this model are consistent with those identified from the actual observation.     

An observational constraint on the existence of proto-superclusters at z =3.3

Observations have been conducted using the Ooty Radio Telescope in order to place constraints on the evolutionary scenario leading to the formation of the present day superclusters. The experiment attempted to detect 21 cm emission from massive neutral hydrogen condensates at a redshift ofz = 3.3. In an Einstein de-Sitter universe with baryon density Ω = 0.05, about ten condensates were expected in the volume surveyed if superclusters, having H I masses ≃5 × 10₁₅ M _⊙, were the first objects to separate out of the Hubble expansion. The sensitivity of our experiment rules out the existence of these condensates atz = 3.3 unless their lifetimes are less than one-tenth the dispersion in their epoch of formation or the proto-superclusters subtend angles greater than 6 arcmin. The result indicates that superclusters form at z > 3.3 if indeed they were the first objects to condense out of the Hubble flow. An erratum to this article is available at .     

松潘地区岩金统计成矿予测中泛克立格法的应用

川西北地区是国内重要的岩金普查靶区。本文对松潘地区的地质特征,泛克立格法原理,及在本区的应用情况作了介绍,对主要计算步骤,给出基本结果,对计算获得的有意义异常区,进行地质解释,并将此方法与趋势面分析进行对比。     

柴达木盆地东部地区石炭系泥页岩生烃条件及选区

柴达木盆地石炭系露头、钻井资料均揭示,其为海相沉积烃源岩,且石炭系泥页岩气展现出良好的勘探前景。对柴达木盆地东部石炭系泥页岩沉积环境、有机质丰度、类型和演化程度进行综合评价,利用野外露头、探井、地震、非震等资料证实了石炭系的残留及分布。研究认为,柴东地区石炭系泥页岩主要集中在上石炭统滨岸潮坪沉积的克鲁克组,发育炭质泥页岩、暗色泥岩2种烃源岩,有机碳均值为3.08%,有机质类型为Ⅱ-Ⅲ型,处于成熟-高成熟演化阶段,73%的样品达到中等-好烃源岩。平面上主要分布于尕丘、欧南、霍布逊和德令哈凹陷,分隔性较强,具有多个厚度中心,其中以欧南凹陷石灰沟地区和霍布逊凹陷落实程度高、资源潜力大,是泥页岩气最有利的发育区。     

苏浙皖边界地区苏皖运动的有关问题

苏皖运动的存在于否,对研究苏浙皖边界地区的地质发展史和正确认识长兴阶地层有重要意义。笔者论证了长兴组的厚度变化、界线粘土层的性质与成因、底砾岩的确认和地层接触关系、古生物群的突变等问题,认为:1)区内苏皖运动是存在的;2)砺山-江阴海堤不可否定;将安徽广德牛头山经江苏宜兴至江阴条带内的龙潭组上部地层作为长兴组的相变产物是不妥的。     

基于生态足迹的区域生态适度人口研究——以新疆生产建设兵团为例

适度人口取决于生态、经济和土地等多要素的综合承载力。介绍了生态足迹模型的基本概念和计算方法,并运用该模型对兵团1995—2008年的生态足迹和生态承载力进行了计算,在此基础上对兵团的1995—2010年的生态适度人口进行了估算。结果表明,1995—1999年兵团的实际人口虽然在增加,但相对于生态适度人口并没有出现过剩;2000—2010年兵团生态适度人口在不断下降,实际人口和过剩人口却在不断增加。兵团目前已经出现了过度人口和生态赤字,人地矛盾相对紧张,生态适度人口规模是不合理的。     

Fermat猜想的两个等价命题

对每个奇素数p,我们提出了关于p的两个命题:(I)不存在正整数m和n,使代数曲线f(y)=y~3-(2m+1)y-2n的三个零点同时为p方有理整数;(I)不存在正整数m,使不定方程x~2+3y~2=4(2m+1)具有三组正整数解x_i,y_i(i=1,2,3),满足x_1=x_2+x_3,x_1~2+x_2~2+x_3~2=6(2m+1)。本文旨在证明(I)及(I)都与关于素数p的Fermat猜想等价。     

Fault structures and their geoelectric parameters in the epicentral zone of the 27 September 2003 Chuya earthquake (Gorny Altai) from resistivity data

This paper presents an integrated measurement technique based on DC methods (vertical electrical sounding, electrical resistivity tomography) which was used to identify faults and determine their geoelectric parameters in the western part of the Chuya basin. New information on the structure of the Chagan River valley located in the zone of the disastrous 27 September 2003 Chuya earthquake has been obtained from the results of these methods. Geoelectric cross-sections of the sedimentary sequence and the upper part of the basement were obtained from VES data, showing the block structure of the study area. Electrical resistivity tomography sections confirm the presence of a major fault between basement blocks of different heights and indicate the presence of faults bounding the valley on its right side and in the southwestern part.     

1951—2008年北京极端天气事件分析

采用湖南14个地市州所在地国家气象站1980—2013年逐分钟降雨资料, 分别利用模糊识别法、芝加哥法、Pilgrim & cordery法及同频率法对各地短历时60 min、90 min、120 min、150 min、180 min以5 min为单位时段的暴雨雨型进行了识别和推求, 结果表明:推求的各地暴雨雨型基本以峰值在前部的单峰型为主; 芝加哥、Pilgrim & cordery计算的峰值、强度相当, 推求的各历时暴雨雨型基本一致, 也更接近实际, 同频率法相对来说效果较差些。

     

Engaging Diasporas for Development: a case study of Pitcairn Island

Diaspora engagement is a growing trend and many governments, international organisations and policy makers are increasingly focusing on the role of diaspora in development strategies for the homelands. Such policies are predominantly critical to island-dense regions such as the Caribbean and Pacific that have suffered high rates of outmigration during the postcolonial period. One such Pacific island is Pitcairn, a British Overseas Territory, and is the focus of this article. But while most of the literature focuses on the positive benefits of diaspora engagement, this paper examines the dynamics of diaspora (dis)engagement and (dis)affection. Each diaspora has a unique set of needs and capabilities based on its historical experience and the present realities of its countries of origin and destination. While much has been written celebrating the role of diasporas in development, diaspora have also shown themselves to have dual natures, with sometimes conflicting identities and allegiances. Based on analysis of a recent Pitcairn Diaspora Survey and ethnographic data, discussion in this paper reveals that the best intentions of engaging diaspora for development can be impeded by several factors including: (1) the complex nature of identity, place and politics; (2) difficult negotiations between past, present and future intentions of movers; and (3) shifting ‘roots/routes’ and boundaries of identification. Consequently, the paper aims to highlight the realities of settlement and relationships of diaspora space and subjectivity with the homeland.