Critical exponents,hyperscaling, and universal amplitude ratios for two- and three-dimensional self-avoiding walks

We make a high-precision Monte Carlo study of two- and three-dimensional self-avoiding walks (SAWs) of length up to 80,000 steps, using the pivot algorithm and the Karp-Luby algorithm. We study the critical exponentsv and 2 ₄ – as well as several universal amplitude ratios; in particular, we make an extremely sensitive test of the hyperscaling relationdv = 2 ₄ –. In two dimensions, we confirm the predicted exponentv=3/4 and the hyperscaling relation; we estimate the universal ratios <R _g ² >/<R _e ² >=0.14026±0.00007, <R _m ² >/<R _e ² >=0.43961±0.00034, and ^*=0.66296±0.00043 (68% confidence limits). In three dimensions, we estimatev=0.5877±0.0006 with a correctionto-scaling exponent ₁=0.56±0.03 (subjective 68% confidence limits). This value forv agrees excellently with the field-theoretic renormalization-group prediction, but there is some discrepancy for ₁. Earlier Monte Carlo estimates ofv, which were 0.592, are now seen to be biased by corrections to scaling. We estimate the universal ratios <R _g ² >/<R _e ² >=0.1599±0.0002 and ^*=0.2471±0.0003; since ^*>0, hyperscaling holds. The approach to ^* is from above, contrary to the prediction of the two-parameter renormalization-group theory. We critically reexamine this theory, and explain where the error lies. In an appendix, we prove rigorously (modulo some standard scaling assumptions) the hyperscaling relationdv = 2 ₄ – for two-dimensional SAWs.     

A Novel Anti-Inflammatory d-Peptide Inhibits Disease Phenotype Progression in an ALS Mouse Model

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterised by selective neuronal death in the brain stem and spinal cord. The cause is unknown, but an increasing amount of evidence has firmly certified that neuroinflammation plays a key role in ALS pathogenesis. Neuroinflammation is a pathological hallmark of several neurodegenerative disorders and has been implicated as driver of disease progression. Here, we describe a treatment study demonstrating the therapeutic potential of a tandem version of the well-known all-d-peptide RD2 (RD2RD2) in a transgenic mouse model of ALS (SOD1*G93A). Mice were treated intraperitoneally for four weeks with RD2RD2 vs. placebo. SOD1*G93A mice were tested longitudinally during treatment in various behavioural and motor coordination tests. Brain and spinal cord samples were investigated immunohistochemically for gliosis and neurodegeneration. RD2RD2 treatment in SOD1*G93A mice resulted not only in a reduction of activated astrocytes and microglia in both the brain stem and lumbar spinal cord, but also in a rescue of neurons in the motor cortex. RD2RD2 treatment was able to slow progression of the disease phenotype, especially the motor deficits, to an extent that during the four weeks treatment duration, no significant progression was observed in any of the motor experiments. Based on the presented results, we conclude that RD2RD2 is a potential therapeutic candidate against ALS.     

General analysis of the measurements of the lateral crystal lattice moduli of semicrystalline polymers by x-ray diffraction and the application to nylon 6

A mathematical representation based on a linear elastic theory is proposed by which one may investigate the dependences of molecular orientation and crystallinity on the crystal lattice moduli and linear thermal expansion coefficients in the direction perpendicular to the chain axis as commonly measured by x-ray diffraction. In the theoretical calculation, a previously introduced model was employed in which oriented crystalline phase is surrounded by oriented amorphous phase and the strains of the two phases at the boundary are identical. The mathematical analysis indicated that the lateral crystal lattice moduli and linear thermal coefficients as measured by x-ray diffraction may be different from the intrinsic crystal moduli and linear thermal coefficients of a crystal unit cell, depending on the structure of the polymer solid. The numerical calculation was applied to nylon 6. As a result, it may be confirmed that the lateral crystal lattice moduli measured by x-ray diffraction are sensitive to the morphology of the bulk speciments and close to the intrinsic crystal moduli if the morphology of the test specimen can be represented by a parallel model with respect to the original stretching longitudinal direction.     

布依族7项不对称行为特征的研究

对布依族的7项不对称行为特征(利手、扣手、叠臂、叠腿、利足、起步和利眼)进行了调查，结果显示：(1)7项指标在布依族中的出现率R型(右型)远高于L型(左型)；(2)布依族中7项指标出现率均无性别间差异；(3)与蒙古族、朝鲜族、汉族、鄂温克族、鄂伦春族、达斡尔族、汉族等民族作比较，发现布依族各项指标L型出现率偏低，且扣手、叠臂、起步L型出现率和这6个民族存在极显著性差异，叠腿L型出现率除与鄂伦春族无差异外，与另外5个民族均有极显著性差异，其他指标与这6个民族基本不存在差异；(4)布依族扣手基因频率(％)为：A=0．1653，a=0．8347；布依族利手基因频率为：B=0．6990，b=0．3010；(5)统计分析了7项指标间的相关性，发现多数指标间存在相关性，部分指标相关极显著，且R—R型组合(右型一右型)的出现频率远高于L—L型组合(左型一左型)的出现频率．     

用POSER5.0制作外踝韧带损伤三维模拟动画的应用研究

外踝韧带损伤是运动中最常见的损伤之一。由于受伤过程常常难以真实地记录下来，给运动损伤预防教学演示带来不便。本研究的目的是制作模拟的外踝韧带运动损伤三维图像，以便较好的解决这一难题。研究的方法是利用Poser5．0所提供的专用三维绘图软件和有机的建模系统，根据相关的专业知识，制作具有良好可视性的动画，以及对运动中受伤过程进行逐帧演示的模拟三维图像。研究结果表明，只要熟练掌握Poser5．0应用软件，就可以使身体的各个部位在运动中受伤的过程以不同的观察角度、多变形态（着装、卡通、骨骼等等）及变化无穷的背景生动地演示出来，从而有效地保证了教学质量。     

光波场在垂直光轴方向的参考面上的复振幅研究

从波动微分波动方程出发推导光波场在垂直光轴方向的参考面上的复振幅表示。     

阿尔金断裂的研究现状及其控油意义

阿尔金断裂是中国西北一条巨型的NEE断裂构造,也是青藏高原的西北边界,它在青藏高原的隆升及中国大陆动力学演化方面有着及其重要的地位,一直成为国内外地学界研究的热点.断裂活动的时间、方式、速度及规模等是阿尔金断裂问题争论的焦点.针对目前国内外研究现状,结合柴达木盆地一些实际资料,认为阿尔金断裂带的活动具有多期次性,而至少在中新世时期开始阿尔金总体呈左行走滑的趋势;阿尔金断裂带对柴达木盆地与塔里木盆地的沉积构造演化起着重要的作用,从而对西部大陆构造格架及两侧盆地油气运聚具有重要的控制意义.     

磁悬浮列车通过隧道时空气阻力的计算方法

首先从空气动力学基本原理出发 ,推导了按非恒定流计算磁悬浮列车在驶入、通过和驶出隧道 3种不同工况下空气阻力的表达式 .然后运用数值方法求出其数值解 ,并与实测和仿真模拟的结果进行比较 .最后分析了空气阻力与各影响因素之间的关系 ,给出了一些合理的解释和建议     

苦楝种核提取物对蛙神经干动作电位的影响

用电生理学方法观察了苦楝种核提取物对蛙离体神经干A，C类纤维动作电位幅度和传导速度的影响，结果显示：浓度为0．1g／ml的苦楝种核提取物对A，C两类纤维复合动作电位的幅度和传导速度均有明显的抑制效应，且C类纤维复合动作电位先于A类纤维被阻断。     

计算机辅助设计在电路教学中的应用

用计算机电路辅助设计的方法对电视机中放电路进行分析，讨论影响中放幅频特性曲线的因素及吸收回路的确定，阐述了将电路CAD引入电路课教学中的可行性和必要性．