VISUALIZATION OF THE CHROMOSOME SCAFFOLD IN A PRIMITIVE EUKARYOTE DINOFLAGELLATE CRYPTHECOAINIUM-COHNII

The chromosome scaffolds in higher eukaryotic nuclei have been described elsewhere. But it is unknown when they evolved. The dinoflagellates are the primitive organisms that may be the intermediate between prokaryotes and eukaryotes. Combining chromosome scaffold preparation methods with embedment-free section microscopy, we demonstrate that the dinoflagellate Crypthecodinium cohnii chromosome retains a protein scaffold after the depletion of DNA and soluble proteins. This scaffold preserves the morphology characteristic of the chromosome. Two-dimensional electrophoreses show that the chromosome scaffolds are mainly composed of acidic proteins. Our results suggest that a framework similar to the chromosome scaffold in the mammalian cell appeared in the primitive eukaryote. We propose that the chromosome scaffold possibly originated from the early stages of eukaryote evolution.

新疆有花背蟾蜍分布的再证实

2007年6～7月在新疆两栖类考察过程中，于乌鲁木齐北京五家渠市安宁渠镇附近(海拔1655 ft,N:44°01.705',E:87°30.763')采集到两种蟾蜍标本.

中能区~(40)Ar + ~(197)Au/~(159)Tb/~(nat)Ag反应中高激发热核性质研究

通过对中能区Ar+Au/Tb/Ag反应中高激发核的发射时标、发射次序、发射机制、核温度、集体运动等衰变特性的研究，提取了轻粒子和中等质量碎片（IMF）的发射时间，IMF发射时间随束流能的升高而变短，发射机制逐渐由相继衰变过渡至多重碎裂。研究了轻粒子和碎片间的发射次序，对高能粒子和碎片，轻粒子先于碎片发射，而低能时，则为碎片先于轻粒子发射。IMF发射成分与角度和碰撞参数有关，前角区来自于弹核碎裂，后角区来自于类靶热核的蒸发。在平面和出平面研究表明，中速粒子和碎片为在平面发射占主导，即存在类转动效应；对轻粒子，转动效应随粒子质量增加而增加；对中速产物均观测到该效应随碰撞参数饿增大而增大。采用几种不同的方法提取了热核的核温度，研究了不同方法之间的区别。

Low-temperature heat capacity and phase transition of n-hexatriacontane

The heat capacities of crystalline and liquid n-hexatriacontane were measured with an automatic adiabatic calorimeter over the temperature range of 80-370 K. Two solid-to-solid phase transitions at the temperatures of 345.397 and 346.836 K, and a fusion at the temperature of 348.959 K have been observed. The enthalpies and entropies of these phase transitions as well as the chemical purity of the substance were determined on the basis of the heat capacity measurements. Thermal decomposition temperatures of the compound were measured by thermogravimetric analysis. (C) 1999 Elsevier Science B.V. All rights reserved.

Stability and Liqueafaction Analysis of Seabed to Wave Loading

波浪作用下海床的稳定性与液化分析是海底管线、防波堤和海洋平台设计中必须仔细考虑的问题。推荐了一个循环荷载作用下土体的弹塑性实用本构模型,并给出了一种粉土的模型参数。该模型直接根据初始应力状态和循环应力的大小与作用时间计算土体的塑性应变增量,在有限元计算中不需要引入弹塑性矩阵。采用Biot理论和有限单元法,计算了粉土海床在波浪作用下的孔隙水压力和有效应力的变化过程,并对海床的稳定性和液化进行了分析。计算结果与波浪槽实验反映的规律是相符的。

Long-range automaton models of earthquakes: Power-law accelerations, correlation evolution, and mode-switching

We introduce a conceptual model for the in-plane physics of an earthquake fault. The model employs cellular automaton techniques to simulate tectonic loading, earthquake rupture, and strain redistribution. The impact of a hypothetical crustal elastodynamic Green's function is approximated by a long-range strain redistribution law with a r(-p) dependance. We investigate the influence of the effective elastodynamic interaction range upon the dynamical behaviour of the model by conducting experiments with different values of the exponent (p). The results indicate that this model has two distinct, stable modes of behaviour. The first mode produces a characteristic earthquake distribution with moderate to large events preceeded by an interval of time in which the rate of energy release accelerates. A correlation function analysis reveals that accelerating sequences are associated with a systematic, global evolution of strain energy correlations within the system. The second stable mode produces Gutenberg-Richter statistics, with near-linear energy release and no significant global correlation evolution. A model with effectively short-range interactions preferentially displays Gutenberg-Richter behaviour. However, models with long-range interactions appear to switch between the characteristic and GR modes. As the range of elastodynamic interactions is increased, characteristic behaviour begins to dominate GR behaviour. These models demonstrate that evolution of strain energy correlations may occur within systems with a fixed elastodynamic interaction range. Supposing that similar mode-switching dynamical behaviour occurs within earthquake faults then intermediate-term forecasting of large earthquakes may be feasible for some earthquakes but not for others, in alignment with certain empirical seismological observations. Further numerical investigation of dynamical models of this type may lead to advances in earthquake forecasting research and theoretical seismology.

过山气流对烟气干扰的水槽模拟实验研究

地处丘陵山区的湖南省某电厂,由于受到复杂的山区气流场和气象条件的控制,电厂烟囱排出的烟气,受过山气流大涡旋运动流场的影啊,严重的污染大片农田及危害人体健康。本文通过利用分层流盐水槽所进行该电厂地形条件的模拟实验。详细的介绍了实验方法以及在中性与稳定层结条件下的流场特性和由于不同流场条件所造成烟气的运动规律。对不同的排烟高度所得到的不同烟气下沉距离进行了比较。从而提出了减少排烟污染的合理烟囱高度和位置。经与现场实测的结果对比,取得了相当一致的结果。

论陀螺的迴转稳定准则及其应用

本文以卡尔丹角为方位参量,建立了轴对称刚体(陀螺)永久转动情形的非线性稳定方程组。应用直接方法证明了具有完全耗散情形的陀螺迴转稳定准则:陀螺绕对称轴自由迴旋稳定的充要条件是转子呈扁形。这一准则不仅为陀螺仪设计提供理论依据,而且为飞行器用自旋稳定实现姿态控制提供理论依据。美国发射的Fxplorer-1号绕长轴自旋失稳和第一颗通讯卫星Syncon号绕短轴自旋取得姿态控制成功的事实都能依据这一准则得到合理解释。

论侧向应力与疲劳裂纹扩展

本文通过对Ⅰ型平裂纹及复合型斜裂纹的疲劳试验说明:虽然平行于裂纹面的正应力(侧向应力)对应力强度因子不起作用,但是对裂纹顶端的塑性变形,从而对疲劳裂纹扩展速率却有明显的影响.相应于同样的应力强度因子幅值,当双轴载荷比λ=1时,侧向应力为零,裂纹扩展最慢;随着λ值减小,裂纹扩展速率增大.因此,在估算疲劳寿命时,如果只考虑应力强度因子幅值的作用,而忽略实验加载条件和实际加载条件下侧向应力差别的影响,必然会带来较大的误差,甚至是不安全的.

含稀疏分布杂质的复合材料中的均匀化稳恒热传导方程

本文应用双空间尺度法导出了含稀疏分布椭圆柱形杂质的复合材料柱中的均匀化稳恒热传导方程,求得了等效导热系数的具体形式,并指出,当杂质枉截面单向分布时,宏观热传导是各向异性的,而当杂质枉截面按方向均匀分布时,宏观热传导是各向同性的.

太阳耀斑可能的储能过程

一般看法是,太阳耀斑的能量源于对流层和光球层,然后逐步堆积到外层的色球和日冕活动区中。所以,分析太阳大气中能量是如何从低层转移到上层的过程,以及分析太阳活动区中无力场能量是怎样堆积起来的机制,显然是讨论耀斑储能过程的中心问题之一。本文从冻结型无力场的基本方程组出发,不仅仅考虑旋转的环形流场,更考虑子午流场之间的相互作用,并具体推算了非定常的时间演化过程。

变截面圆轴扭转问题用非正交曲线坐标的新解法

本文是在飞机发动机涡轮轴应力分析的基础上提高为变截面圆轴扭转问题的一个新解法.利用向量的散度和旋度对不同坐标系是不变量的特点,通过张量分析推导出在任意非正交曲线坐标系中变截面圆轴扭转问题的平衡和协调方程,包括用应力函数表达的协调方程和应力函数与应力分量的关系式.用任意非正交曲线坐标和差分法求解应力函数.本文计算得到了全轴的等应力函数线和剪应力分布,并得到沿小凹槽边任意点的应力,计算结果和光弹试验结果接近.本文还计算了有解析解的空心锥轴,误差小于百分之一.通过计算说明本文提出的新解法收敛性很好,并且所需计算机容量少(可在容量32k的TQ-16机上同时计算800多个节点),应用方便,便于编排通用程序,计算量较有限元法少;另一方面,由于采用了任意非正交曲线坐标,因此,适用于解决复杂曲线边界的问题,提高了通常用的差分法的适应性和灵活性;此外,本方法用应力函数作为未知量,从所得的等应力函数线和等位移函数线图可以看出全轴应力分布的概况,对于改进设计很有帮助.