EOS and Single Particle Properties of Asymmetric Nuclear Matter

We have investigated the equation of state (EOS) and single particle (s.p.) properties of asymmetric nuclear matter within the framework of the Brueckner-Bethe-Goldstone approach. We have discussed particularly the effect of microscopic three-body forces (TBF). It is shown that the TBF affects significantly the predicted properties of nuclear matter at high densities.

Nucleon Superfluidity in Asymmetric Nuclear Matter and Neutron Star Matter

We have investigate the nucleon superfluidity in asymmetric nuclear matter and neutron star matter by using the Brueckner-Hartree-Fock approach and the BCS theory. We have predicted the isospin-asymmetry dependence of the nucleon superfluidity in asymmetric nuclear matter and discussed particularly the effect of microscopic three-body forces. It has been shown that the three-body force leads to a strong suppression of the proton S-1(0) superfluidity in beta -stable neutron star matter. Whereas the microscopic three-body force is found to enhance remarkably the (PF2)-P-3 neutron superfluidity in neutron star matter and neutron stars.

MEASUREMENT OF TWO-PROTON CORRELATION FROM THE BREAK-UP OF Al-23

Experiments of Al-23 and Mg-22 radioactive beams bombarding a C-12 target at an energy of 60 similar to 70 A MeV have been performed at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility to study the two-proton emission from Al-23 and Mg-22 excited states, respectively. The trajectorie of the decay products, namely Na-21 + p + p from Al-23 and Ne-20 + p + p from Mg-22, are clean identified. The relative momentum and opening angle between two protons in the rest frame of three body decay channels are obtained by relativistic-kinematics reconstruction. The results demonstrate that there are some di-proton emission components from He-2 cluster for the excited Al-23 and Mg-22.

NUCLEON-NUCLEON CROSS SECTIONS IN ISOSPIN ASYMMETRIC NUCLEAR MATTER

The in medium nucleon-nucleon (N N) cross sections in isospin asymmetric nuclear matter at various densities are investigated in the frame work of Brueckner-Hartree-Fock theory with the Bonn B two-body nucleon-nucleon inter action supplemented with a new version microscopic three-body force (TBF). The TBF depresses the amplitude of cross sections at high density region. At low densities, the proton-proton and neutron-neutron cross sections decrease while the proton-neutron one increases as the asymmetry increases. But the sensitivity of the N N cross sections to the isospin a symmetry are reduced with the increasing density.

用RIMS研究低能He2+与Ar碰撞的多电子过程

用反冲离子动量谱仪研究了低能He2+与Ar碰撞的多电子交换过程。该技术的独特优势是对反冲离子末态动量的完全测量。实验上鉴别了单电子俘获SC，双电子俘获DC和转移电离TI各子过程，并得到了末态量子态布居信息，首次测量了该体系各反应道的角微分截面及直接与碰撞参数相关的信息。实验发现电子主要俘获到入射离子基态或单激发态，反冲离子处于单激发态或多激发态，并有较大几率形成空心离子。研究表明电荷交换过程中存在较强的电子-电子关联作用。角分布随反冲离子电荷态增加而变宽，并向大角度方向移动，表明碰撞参数减小，相互作用加剧。SC和DC与MCBM理论角微分截面符合很好，说明在大碰撞参数时经典近似有一定合理性。不同碰撞参数范围内反冲纵向动量分布表明，SC在碰撞参数7.2a.u.≥b≥3.6a.u.时发生机率最大，随碰撞参数减小，靶离子有不断向更高激发态过渡的趋势

三体核力对核物质中基态关联效应和中子星物质中1S0态质子超流性的影响

本论文介绍了极端条件下核物质性质研究的现状以及目前常用的几种微观核多体方法，系统描述了核物质中的基态关联效应、温度效应对单核子势的影响和同位旋非对称核物质 态中子、质子超流性，重点考虑了利用介子交换流方法建立的微观三体核力所产生的影响。利用BHF和BCS的理论方法,计算了同位旋非对称核物质中 态中子和质子的对关联能隙，着重讨论了三体核力的影响。结果表明，三体核力对同位旋非对称核物质中 态的中子超流性影响相对较小，但是对 态的质子超流性具有重要影响，其效应随总核子数密度的增大而迅速增强。随着同位旋非对称度 的增加，中子能隙向低密移动，能隙峰值逐渐增大，并且这种效果随着 的增加而逐渐减弱，而质子的情况刚好相反。另外还参与了 稳定中子星物质中超流性的研究。利用质量算子空穴线展开，通过计算不同温度和密度下的核物质中单核子势和核子有效质量，重点研究和讨论了基态关联效应和三体核力贡献对热核物质中单核子势的影响，研究表明：基态关联效应提供了一个排斥效应，温度和三体核力都削弱了基态关联效应

中子及中子星物质中的3PF2态超流性和微观三体核力效力效应

本论文介绍了当前中子及中子星物质中超流性研究的背景及现状、核多体理论Brueckner-Hartree-Fock及同位旋相关的Brueckner-Hartree-Fock方法，以及利用BHF和BCS理论计算中子及中子星物质中的对关联能隙方法。系统计算并描述了中子及中子星物质中子的3PF2态超流性，并重点考虑了利用介子交换流方法建立的微观三体核力所产生的影响。 我们的研究结果表明：三体核力对中子物质中3PF2态中子超流性有强烈的增强效应。 当在BCS能隙方程中采用自由粒子能谱近似时，三体核力使相应的对关联能隙峰值增加了77%(由0.64MeV增大到1.13MeV)；当采用自洽BHF单粒子能谱时，三体核力导致相应的对关联能隙峰值由0.22MeV增大到0.50MeV，增加了约127%。 三体核力使中子星物质中3PF2态中子超流能隙随着密度的增大而单调递增。当采用自洽BHF单粒子能谱时不考虑三体核力时，对关联能隙峰值在密度约1.9fm-3时有峰值0.19MeV。而在这个两体力导致的能隙的峰值密度，三体核力导致相应的对关联能隙由0.19MeV增大到0.36MeV

三体核力影响下的核物质状态方程及中子星物质中的中子质子超流性

本论文介绍了极端条件下核物质研究的现状以及目前常用的几种核多体方法，系统描述了冷、热非对称核物质的状态方程和刀稳定中子星物质中的15。态中子和质子超流性，特别是微观三体核力对此所产生的影响。通过引入微观三体核力，扩展了有限温度的BI．tleclcller-Hal'tree-Fock（FTBHF）理论。利用这一扩展的理沦，详细研究了同位旋非对称热核物质的状态方程、液气相变临界现象以及三体核力对此所产生的影响。在不同的中质比条件下，重点讨论了热核物质液气相变的临界温度和动力学不稳定区域的温度、同位旋相关性。由此表明，三体核力的引入在一定程度上降低了液气相变的临界温度值，在固定的温度和密度下，非对称核物质的压弧随同位旋非对称度的增加而单调的增力日，而且随着核物质温度的升高和非对称度的增加，动力学不稳定区域逐渐缩小。通过与其它理论模型（特别是Di1'ac-BHF方法）所预言的结果相比较，就目前扩展的包含三体核力修正的FTBHF理论与Dilac-BHF方法所计算的临界温度的差异问题，文中给出一种可能的解释。通过计算热核物质的单粒子结合能，给出了有限温度条件下对称能的计算方式，并且细致研究了不同温度、密度下的对称能以及三体核力在高密度区域对对称能的影响。结果表明，微观三体核力强烈影响着高密度区域的对称能，使其对温度的变化更加明显。此外，其它重要物理量（例如中子和质子的单粒子势能、有效质量等）的同位旋依赖性和温度、密度相关性在文中也被详细的讨论。利用质量算子的空穴线展井，表明了在基态关联所导致的对单核子势的重排修正项影响下的HLlgenholtz-VanHove(HVH)定理的恢复程度，并且进一步计算了中子和质子化学势。并且以包含兰体核力的FTBI-方法为基础，研究了热核物质中重排项的密度和温度依赖性并讨论了三体核力对重排项的影响。通过计算不同温度和密度下的核物质中单核子势和核子有效质量，特别是研究和讨论了基态关联效应和三体核力贡献对热核物质中单核子势的影响，表明了基态关联和三体核力对单核子势修正的重要性。利用BHF和BCS的理论方法，计算了β稳定中子星物质中处于150态的中子和质子的对关联能隙，着重研究和讨论了三体核力的影响。结果表明，三体核力对刀稳定物质中｛s0态中子超流性的影响相对较小，但是对，S0态质子超流性具有重要影响，其效应随核子数密度的增大而迅速增强。三体核力的主要作用是强烈地抑制了高密度区刀稳定中子星物质中的150态质子超流性，而且三体核力对中子星物质中，So态超流相的抑制效应主要是通过质子或中子的有效对相互作用而起作用的。

Compensatory growth response in three-spined stickleback in relation to feed-deprivation protocols

Different protocols of food deprivation were used to bring two groups of juvenile three-spined sticklebacks Gaslerosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum. One group experienced I week or deprivation then 2 weeks on maintenance rations. The second group experienced I week of ad lithium feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass ore. 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the three-spined sticklebacks had reached the reduced body mass. The compensatory response was Sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipid-free dry mass. Hyperphagia and increased growth efficiency were present in the re-feeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature three-spined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts. (C) 2003 The Fisheries Society of the British isles.

Three-dimensional crack problem analysis using boundary element method with finite-part integrals

A set of hypersingular integral equations of a three-dimensional finite elastic solid with an embedded planar crack subjected to arbitrary loads is derived. Then a new numerical method for these equations is proposed by using the boundary element method combined with the finite-part integral method. According to the analytical theory of the hypersingular integral equations of planar crack problems, the square root models of the displacement discontinuities in elements near the crack front are applied, and thus the stress intensity factors can be directly calculated from these. Finally, the stress intensity factor solutions to several typical planar crack problems in a finite body are evaluated.

Elastodynamic stress intensity factor history for a semi-infinite crack under three-dimensional transient loading

The dynamic stress intensity factor history for a semi-infinite crack in an otherwise unbounded elastic body is analyzed. The crack is subjected to a pair of suddenly-applied point loadings on its faces at a distance L away from the crack tip. The exact expression for the mode I stress intensity factor as a function of time is obtained. The method of solution is based on the direct application of integral transforms, the Wiener-Hopf technique and the Cagniard-de Hoop method. Due to the existence of the characteristic length in loading this problem was long believed a knotty problem. Some features of the solutions are discussed and graphical result for numerical computation is presented.

Numerical study of bluff body flow structures

Our recent progress in numerical studies of bluff body flow structures and a new method for the numerical analysis of near wake flow field for high Reynolds number flow are introduced. The paper consists of three parts. In part one, the evolution of wake vortex structure and variation of forces on a flat plate in harmonic oscillatory flows and in in-line steady-harmonic combined flows are presented by an improved discrete vortex method, as the Keulegan-Carpenter number (KC) varies from 2 to 40 and ratios of U-m to U-0 are of O(10(-1)), O(10) and O(10), respectively. In part 2, a domain decomposition hybrid method, combining the finite-difference and vortex methods for numerical simulation of unsteady viscous separated flow around a bluff body, is introduced. By the new method, some high resolution numerical visualization on near wake evolution behind a circular cylinder at Re = 10(2), 10(3) and 3 x 10(3) are shown. In part 3, the mechanism and the dynamic process for the three-dimensional evolution of the Karman vortex and vortex filaments in braid regions as well as the early features of turbulent structure in the wake behind a circular cylinder are presented numerically by the vortex dynamics method.

Variation in Reproductive Traits between Populations of Neosalanx taihuensis above and below the Three-Gorges Dam

Reproductive characteristics of the spring spawning stock of Neosalanx taihuensis varied significantly between the populations in the Three-Gorges Reservoir (TGR) and in the Tian-e-zhou Oxbow (TEO, below the dam). Larger body size, higher condition, higher fecundity, and larger oocyte diameter of the spawning stock in the TGR indicated faster individual growth and higher reproductive investment of the TGR population than the TEO population. With higher population abundance associated with higher reproductive investment of N. taihuensis in the TGR than in the TEO population, we suggest that reproductive investment is an important factor regulating resource fluctuation of N. taihuensis populations.

Effect of cycles of feed deprivation on growth and food consumption of immature three-spined sticklebacks and European minnows

Individual juvenile three-spined sticklebacks Gasterosteus aculeatus and European minnow Phoxinus phoxinus, from sympatric populations, were subjected to four cycles of I week of food deprivation and 2 weeks of ad libitum feeding. Mean specific growth rate during the weeks of deprivation was negative and did not differ between species. The three-spined stickleback showed sufficient growth compensation to recover to the growth trajectory shown by control fish daily fed ad libitum. The compensation was generated by hyperphagia during the re-feeding periods, and in the last two periods of re-feeding, the gross growth efficiencies of deprived three-spined sticklebacks were greater than in control fish. The expression of the compensatory changes in growth and food consumption became clearer over the successive periods of re-feeding. The European minnow developed only a weak compensatory growth response and the mass trajectory of the deprived fish deviated more and more from the control trajectory During re-feeding periods, there were no significant differences in food consumption or gross growth efficiency between control and deprived European minnows. The differences between the two species are discussed in terms of the possible costs of compensatory growth, the control of growth and differences in feeding biology (C) 2003 The Fisheries Society of the British Isles.

Compensatory growth in the gibel carp following feed deprivation: temporal patterns in growth, nutrient deposition, feed intake and body composition

To investigate the nature of compenstory growth in fish, an 8 week study at 28 degreesC was performed on juvenile gibel carp Carassius auratus gibelio weighing 6.6 g. Fish were starved for 0 (control), 1 (Sl)or 2 (S2) weeks and then re-fed to satiation For 5 weeks. Weekly changes in weight gain, feed intake and body composition were monitored during re-feeding. No significant difference was found in final body weight between the three groups, indicating complete compensation in the deprived fish, The deprived groups caught up in body weight with that of the control after 2 weeks of re-feeding. Body fat:lean body mass ratio was restored to the control level within 1 week of re-feeding. In the re-feeding period, weekly gains in body weight, protein. lipid, ash and energy in the S1 group were significantly higher than in the controls for 1 week. For the S2 group, weekly gains in body weight. lipid. ash and energy were higher than in the controls for 2 weeks, and gain in protein was higher than in the controls for 3 weeks, though gain in body energy became elevated again during the last 2 weeks of the experiment. Feed intake remained higher than the control level for 3 weeks in the S1 group and 3 weeks in the SZ group. Growth efficiency was not significantly different among the three groups in any of the weeks during re-feeding. Compensatory responses in growth and especially feed intake tended to last longer than the recovery of body composition. (C) 2001 The Fisheries Society of the British Isles.