高等真核生物基因组isochore边界确定中的对称性

高等真核生物基因组的isochore结构与许多重要的生物学特征相关,而对其边界的确定则是isochore结构分析的重点,同时也是难点.针对基于Z曲线的累积GC轮廓图法、基于Shannon熵的递归分段算法以及基于二次散度的分段算法三种典型的应用,分析出其分段依据本质上是对于基因组序列求取碱基对换对称性的对称中心.基于此结果,在寻找isochore结构分析度量时,只要度量函数满足一定对换对称性要求,即可达到殊途同归的目的.

Variations in Isochore Thickness of the Ecca Sediments in the Eastern Cape Province of South Africa,as Deduced from Gravity Models

Gravity modelling was carried out along five profiles that traverse the Eastern Cape Province of South Africa in order to determine the depositional surface and isochore thickness of the Ecca sediments.Gravity models of the subsurface rock density reveal that the Ecca Group has a maximum vertical thickness of about 3215 ± 160 m.The maximum depositional surface（elevation）above sea level for the Ecca sediments is about 500 m,whilst the depth below sea level reaches about10000 m.Correlation of the isochore thickness maps with the depositional surfaces shows that the sediments in the basement highs were subsided,deformed,eroded and deposited in the basement lows.The basement highs served as the source area（s） for the sediments in the basement lows,thus basement highs are characterized with thin sediment cover whilst the lows have thick sediment cover.

人类基因组isochore边界的保守性研究

人类基因组由一些较长的,G+C含量相对均匀的DNA片段组成,也就是我们所说的isochore结构。Isochore结构与许多重要的生物学特征相关,如:基因密度、CpG岛等,关于这些已有系统的研究。我们使用基于Z曲线理论的基因组序列分段算法,在单核苷酸精度的水平上定位了人类基因组56个isochore的边界,共得到79个独立的边界。我们发现在这79个边界中,45.6%的isochore边界在与17个脊椎动物基因组比对时,显示出明显的保守性,比如:某段高保守的序列在isochore边界处转换为一段弱保守或者完全不保守序列。另外isochore边界附近的序列组成高度保守。通过和已被实验证实的复制开关点附近的序列相比较。有理由推断这79个isochore边界都有可能是人类基因组中的复制开关位点,这一点有待实验验证。

Determination of inner pressure for fluid inclusions by Raman spectroscopy and its application

Using a Diamond Anvil Cell combined with micro Raman spectroscopy, the quantitative relations among Raman shifts, pressure and temperature were obtained for the vibration of O-H in H2O-NaCl, C-O in CO3^2-, S-O in SO4^2- and C-H in n-heptane-cyclohexane. Based on the quantitative relationships obtained, it is possible to determine the inner pressure for single fluid inclusions and to further determine the isochore of the systems. It is not only helpful to obtain the forming temperatures and pressures of the enclosing minerals, but also to be able to provide information concerning the chemical compositions of the fluid inclusions.

Absolute Internal Energy of the Real Gas

The internal energy U of the real, neutral-gas particles of total mass M in the volume V can have positive and negative values, whose regions are identified in the state chart of the gas. Depending on the relations among gas temperature T, pressure p and mass-specific volume v=V/M, the mass exists as a uniform gas of freely-moving particles having positive values U or as more or less structured matter with negative values U. In the regions U>0?above the critical point [Tc , pc , vc] it holds that p(T,v)>pc and v>vc, and below the critical point it holds that p(T,v)c and v>vv , where vv is the mass-specific volume of saturated vapor. In the adjacent regions with negative internal energy values Uc is the line of equal positive and negative energy contributions and thus represents a line of vanishing internal energy ?U=0. At this level along the critical isochor the ever present microscopic fluctuations in energy and density become macroscopic fluctuations as the pressure decreases on approaching the critical point;these are to be observed in experiments on the critical opalescence. Crossing the isochor vc from U>0 to UΔU>0 happens without any discontinuity. The saturation line vv also separates the regions between U>0 and U , but does not represent a line U=0. The internal-energy values of saturated vapor Uv and condensate Ui can be determined absolutely as functions of vapor pressure p and densities (M/V)v and (M/V)i , repectively, yielding the results Uiv, U=Ui+Uvc and U=Ui=Uv=0 at the critical point. Crossing the line Vv from U=Uv>0 to U=Uv+UiΔU=-Ui>0 to be removed from the particle system. The thermodynamic and quantum-mechanical formulations of the internal energy of a particle system only agree if both the macroscopic and microscopic energy scales have the same absolute energy reference value 0. Arguments for the energy reference value in the state of transition from bound to freely- moving particles in macroscopic classical and microscopic quantum particle systems are discussed.

Unusual high-density and saline aqueous inclusions in ultrahigh pressure metamor- phic rocks from Sulu terrane in eastern China

Primary high-density fluid inclusions were identified in garnet from ultrahigh pressure eclogite in the southern part of the Sulu terrane. They occur isolatedly or in cluster together with relatively low-density two-phase inclu-sions. The eutectic temperature of the inclusions is as low as ≤ -52℃. A bubble was nucleated in a liquid inclusion dur-ing the specific stage of cyclic cooling-heating runs, and the liquid-gas homogenization temperature was measured to be ≤-12.5℃. The composition of the inclusions modeled by the system CaCl2-NaCl-H2O, yields the fluid density of 1.27g/cm3 that corresponds to a pressure of ca. 2.4 GPa at thetemperature of peak eclogite-facies metamorphism, close tothe ultrahigh pressure metamorphic conditions. During theexhumation of the eclogite the inclusions reacted with thehost mineral, forming hydrous silicate minerals that resulted in lowering of the fluid density and its transformation to multi-phase inclusions.

Thermodynamic Modeling of Ternary CO_2-H_2O-NaCl Fluid Inclusions

Up to now,fluid inclusion is still a powerful tool to estimate the temperature and pressure of various geological processes.CO_2-bearing inclusions are commonly found in many environments.Among the CO_2-bearing inclusions,the most typical are the ternary CO_2-H_20-NaCl inclusions.These saltbearing CO_2 V-L inclusions at room temperatures are coexisting H_2O liquid +CO_2 liquid +CO_2 vapor or coexisting H_20 liquid +CO_2 liquid(or vapor).On heating they often finally homogenize to liquid phase by the bubble disappearance,and they may form CO_2 hydrate and ice during cooling.This paper reports the application of thermodynamic models,including equations of state,to ternary CO_2-H_20-NaCl fluid inclusions.Some simple equations for pressure-temperature-salinity relation on the CO_2 hydrate-liquid-vapor(liquid) surface are developed to calculate the NaCl contents(salinities) of inclusions.With these relations and the latest CO_2 solubility and PVTx models,a new iterative approach is presented to calculate the CO_2 contents of CO_2-H_20-NaCl inclusions on the assumption that the bulk molar volume of an inclusion keeps constant at the disappearances of CO_2 hydrate and vapor bubble.A prominent merit of this method is that the compositions,molar volumes and homogenization pressures of CO_2-H_20-NaCl inclusions can be simultaneously obtained without using experimental optical volume fractions of vapor bubbles at the dissociation temperatures of CO_2 hydrates.Meanwhile,the homogenization pressures and isochores of CO_2-H_2O-NaCl fluid inclusions from updated models are briefly discussed.Calculation program code for the ternary CO_2-H_2O-NaCl inclusions with microthermometric measurement and Raman analysis data as input variables can be obtained from the author.

Correlation of cooperatively localized rearrangement on the "fluidized domain" in glass substances (or polymers) to their fragility Ⅲ:Theory of dynamic fragility at isochoric state

A set of universal equations on the reduced stress relaxation modulus with K-W-W stretched exponential function has been derived from the dynamics of α and β structural relaxation processes. In the present work, the K-W-W decay function is used to define the three types of relaxations (single α, single β relaxation and α-β co-relaxation), then their average times of relaxation are theoretically calculated from the reduced shear stress relaxation modulus and the relaxation time spectrum function H(τ). When the average time of co-relaxation, the reference temperatures (ficitive Tf and glass transition Tg) and the isostructural parameter achieved from the conditions of isostructural glass state are introduced into the reduced shear stress relaxation modulus (GT) under the equilibrium state, a set of correlations between isochoric fragility index (mvα, mvβ and mvαβ) and the coupling strength (α and β) under the reference temperatures are derived from the exact definition of isochoric fragility. So the theory of dynamic fragility for glass substances at isochoric state is developed. The theory can predict the following main features of structural relaxations and behavior of isochoric fragility: the temperature dependence of peak relaxation frequency exhibits a bifurcation with a pair of single α and single β relaxations; the temperature dependence of Stickel equation on 1/T exhibits two crossovers with VFTH(1) and VFTH(2) at the temperatures of Tf and Tg regime; there are two linear correlations between isochoric fragility index (mvα and mvβ) and the coupling strength. Fine agreements between the theoretical calculation and experimental results are obtained.