体内受精许氏平鲉(Sebastes schlegelii)和体外受精大菱鲆(Scophthalmus maximus)精子结构及生理特性比较

为了解硬骨鱼许氏平鲉精子体内受精以及精子在雌性体内保持长期存活的特性,本研究应用扫描电镜与透射电镜对体内受精卵胎生硬骨鱼许氏平鲉与体外受精卵生大菱鲆的精子进行超微结构观察,并使用计算机精子分析系统比较精子激活后运动参数差异。结果显示,这两种鱼的精子均由头部,中段和尾部构成,无顶体,尾部轴丝为“9+2”微管结构。许氏平鲉精子特点：头部呈短棒状,细胞核呈长锥状;中段不对称,约30—40个线粒体呈垛叠状紧密排列在中段;轴丝质膜延伸形成的侧鳍较为发达。大菱鲆精子特点：头部呈椭圆形,头部和鞭毛结构松散,含有大量囊泡状结构;精子中段较短,向外突出的线粒体包裹鞭毛形成“半袖套”结构且尾部鞭毛侧鳍不发达。许氏平鲉精子密度和体外激活寿命均显著高于大菱鲆精子,而激活后精子的平均曲线速度（VCL）、平均直线运动速度（VSL）、平均路径速度（VAP）显著低于大菱鲆精子。研究表明,上述精子结构差异主要表现在精子头部与中段：体内受精硬骨鱼精子大多具有细长的头部,发达的中段,线粒体数量较多;体外受精硬骨鱼具有圆形或椭圆形的头部,中部不明显,线粒体较少。     

Observations on fabric evolution to a common micromechanical state at the soil-structure interface

The fabric plays an important role in the mechanical behavior of granular material. The aim of this paper is to investigate the evolution of fabric in a soil-structure interface (SSI) to a large shearing in an effort to clarify whether and how this form of fabric evolution can lead to a common microstructure. Using the discrete element method (DEM), two-dimensional (2D) numerical interface shear tests were carried out, and certain macromechanical and micromechanical properties were exploited. All samples exhibited prominently localized strain in a zone covering the structure's surface (named the localized zone), and much lower density and higher soil fabric anisotropy levels were found inside this zone than outside it. Disregarding different initial void ratios, a common critical state microstructure was observed in large shear deformations of soil samples, with essentially the same fabric arrangement in terms of contact orientation and internal force transmission. Due to the systematic forming, buckling, and collapsing of force chains, an angular zone (called an α -zone), in which contact density was sluggish to varying degrees, appeared and extended around the main direction of the distribution of contact orientation inside the localized zone. The gradual deterioration of the force chains' stability, as a result of an increasing void ratio, seemed to drive the α -zone's extension and lead to the rare variation of microstructures in the critical state.     

新疆经济发展与资源、灾害和构筑西亚—西欧海陆大通道的思考

新疆维吾尔自治区地处中国西部边陲,地域广阔,少数民族众多且聚居,金属矿产资源、石油、天然气、煤等能源矿产十分丰富,在经济与文化上相对欠发达。其经济发展和建设在中国新疆可持续发展的进程中有着极大的潜力。目前,应当清晰地看到新疆的矿产资源勘探和开发尚处在一片混乱与无序之中,基础设施和研究、整体发展方针和科学布局尚十分不足。由于目前资源、能源勘探和开采进程仍属初期阶段,涉及的探查深度还很浅(即第一深度空间:0~500 m),而第二深度空间(500~2000 m)的金属矿产资源尚有待勘探与探查环境的改善。当今在先进技术引进、应用和高新科技人才凝集力度上还急待增强和迅速发展与改善。还应当指出,新疆、特别是天山地震带具有发生大地震的潜在危险性。这充分表明,新疆维吾尔自治区在经济和社会发展进程中已具备了必要条件,但尚不具备可实施的充分条件。当然经济要发展,社会要进步,则必须具备必要和充分条件及二者有机的耦合和不断完善。为此走跨越式的发展道路已为必然,且必将成为建设新疆的动力源泉。在这样的前提下,在党中央和国务院提出的国家战略需求和自主创新的方针指导下,新疆应当怎样发展,本文简要讨论了四个方面的问题:(1)中国西域安全、稳定的社会和经济发展轨迹与资源战略后备基地;(2)加强自治区与周边地带地震活动监测与抗震及预测;(3)打造喀什大商埠、构筑西亚—西欧海陆科技、商贸与文化交流大通道的思考;(4)强化自治区内一体化信息与传媒体系的一元化和和谐文化建设。     

许氏平鲉(Sebastes schlegelii)卵子发生及妊娠过程中雌激素、芳香化酶及其受体的变化规律

雌二醇是鱼类卵巢分泌的主要的性类固醇激素之一,在脊椎动物卵子发生、性别分化、卵黄形成、生理免疫以及中枢神经系统调节等生理过程中发挥重要的作用。许氏平鲉营胎生繁殖,且经过漫长的卵黄积累期和妊娠期,这一特殊的生殖方式使得它受到了国内外学者的广泛关注。通过分析与雌二醇合成及作用密切相关的cyp19a和Era在许氏平鲉卵巢上的定位、cyp19a和cyp19b mRNA在不同卵巢发育时期及不同组织中的表达以及不同发育期的卵巢中雌二醇含量变化,发现在卵巢发育的过程中,许氏平鲉体内雌二醇含量的峰值出现在IV期和体节期。并且cyp19a和cyp19b在卵巢中均有表达且在不同的卵巢发育期表达量不同。在卵黄积累的过程中, cyp19a和cyp19b在IV期的表达量最高,在妊娠时体节期表达量最高。不仅如此,在V期卵巢的滤泡层、基质和囊胚期的滤泡胎盘上检测到了强烈的Era的信号。这些结果说明雌二醇在胎生鱼类卵子发生及妊娠过程中均起到非常重要作用。这一研究为深入解析许氏平鲉胎生生殖特性积累了资料。     

薄层时频特征的正演模拟

基于正演模拟的薄层时频特征响应分析是薄层定性识别与厚度定量预测的基础与关键.本文基于波场延拓理论,利用深度域相移法对不同厚度薄层进行了正演模拟.采用广义S变换对零偏移距地震道的反射复合波进行瞬时频谱分析,发现当薄层顶底反射系数极性相反时,复合波的干涉作用具有升频降幅作用,而极性相同时具有升幅降频作用;理论推导和实验分析均证明主峰值频率与薄层双程旅行时间厚度存在定量解析关系,这为薄层厚度定量预测提供了重要的技术手段;由于峰值频率对反射系数大小与极性变化不敏感,因此,峰值频率方法与时域振幅方法相比更具稳定性.     

秦岭造山带与南北相邻地带远震接收函数与地壳结构

从2013年3月至2014年11月,我们布设了一条延川—涪陵的流动宽频带地震台阵,剖面由70个流动台站组成,全长约900km,穿越华北克拉通、秦岭—大巴造山带和扬子克拉通东北缘陆内三大构造单元.利用记录到的远震波形资料,提取得到5638个远震P波接收函数,使用H-κ叠加扫描和CCP偏移叠加方法刻划了秦岭造山带与南北相邻地带的地壳厚度、泊松比以及构造界带.研究结果显示,(1)关于地壳厚度:地壳最厚的区域出现在大巴山,地壳厚度集中在47~51km之间,秦岭的地壳厚度相对大巴山较薄,且呈向北减薄趋势,集中在37~46km之间,渭河盆地地壳厚度为本区域最薄地带,在34°N左右处达到最薄为35km,剖面北侧的南鄂尔多斯盆地的地壳厚度变化缓慢,多为44km左右,南侧的四川盆地东北缘的地壳厚度向南缓慢减薄,集中在42~48km之间;(2)关于泊松比:使用接收函数H-κ叠加扫描法得到了沿剖面各台站下方地壳的平均纵、横波速度比VP/VS(κ),进一步计算得到泊松比σ,泊松比具有明显的横向分块特征,秦岭造山带的泊松比明显低于南北两侧区域,其小于0.26的泊松比表征着该区域地壳物质组分主要为酸性岩石,亦即其酸性长英质组分上地壳相对于基性铁镁质组分下地壳较厚,该区域没有高泊松比分布则表明不存在广泛的部分熔融.(3)关于构造界带:秦岭—大巴造山带与扬子克拉通的边界并非在勉略构造带,应向南移至四川盆地的东北缘,华北克拉通和扬子克拉通分踞秦岭—大巴造山带南、北两侧,且分别以较陡倾角向南和相对较缓的倾角向北俯冲于秦岭—大巴造山带之下,使得秦岭—大巴造山带呈不对称状扇形向外扩展与向上抬升的空间几何模型.秦岭和大巴山之间33°N附近存在分界面,两区域地壳厚度与泊松比特征各异.     

A new Cosserat-like constitutive model for bedded salt rocks

Salt rocks are commonly used as geologic host rocks for storage of gas and crude oil, and are being considered for the disposal of radioactive waste. Different from the salt rock domes in many countries, the salt rock formations in China are usually laminar with many alternating layers, i.e. rock salt, anhydrite, and/or mudstone. Considering the unique stratigraphic characteristics of these salt rocks, a new Cosserat-like medium constitutive model is proposed in order to facilitate efficient modeling of the mechanical behavior of these formations. In this model, a new representative volume element, containing two different layers, is employed to simulate the compatibility of the meso-displacement between two different layers and also the bending effect. A new method for the deformation and failure analysis of bedded salt rocks is derived therefrom. Having the macro-average stresses, the conventional stresses in the different layers can be obtained in sequence. The conventional stresses can then be utilized in a routine way for the strength and failure analysis. For the initial numerical modeling, the new Cosserat-like medium is reduced to a transversely isotropic one. The simplified constitutive model for layered media is then implemented into FLAC3D codes. A test sample validates that the results by using the numerical model are in good agreement with that by using the built-in model, and the mesh size for the new model is reduced greatly. Finally, an application for the stability of oil storage caverns in deep thinly bedded salt rocks is carried out. The effects on convergence of storage caverns and on the failure of surrounding rock due to the presence of the mudstone interlayers (hard phase) are discussed in detail. Copyright © 2009 John Wiley & Sons, Ltd.     

二阶Born近似有限频率走时敏感核

有限频率层析成像考虑了非均匀介质中波的散射、衍射、波前愈合等物理性质,使得其对速度异常体的分辨能力远大于射线层析成像.推导和计算有限频率敏感核是进行有限频率层析成像的关键,当前推导有限频率敏感核多借助一阶Born近似,但这只适用于弱散射介质的情况.本文基于二阶Born近似并利用傅里叶变换推导了三维均匀介质情况下有限频率敏感核的解析表达式,并将其推广到非均匀介质中得到了三维非均匀介质中有限频率敏感核.研究表明:当介质中速度扰动小于2%时,基于二阶Born近似的有限频率敏感核与基于一阶Born近似的有限频率敏感核差别很小,可近似认为相同;当介质中速度扰动大于5%时,基于二阶Born近似的有限频率敏感核与基于一阶Born近似的有限频率敏感核有较大不同,表明此时已不能忽略二次散射.     

Seismogenic mechanism of the Lancang and Gengma earthquakes

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