Non-covalent Surface Interactions between Silicone and Biological Macromolecules Yield Bioreactive Substances

While most organometallics enter the en- vironment through their industrial release, silicones are organometallic compounds purposefully introduced in high volume directly into healthy humans. A chemically centered study of the behavior of silicones in the biological environment reveals numerous de- gradative reactions and surface interactions that can produce bioreactive substances. Data from a variety of disciplines suggest that the preponderance of evidence supports the argument that silicone is a toxic organometallic. © 1997 by John Wiley & Sons, Ltd.     

Bifurcation analysis on a discrete model of Nicholson's blowflies

In this paper, the discrete Nicholson's blowflies model with delay is considered. First, the stability of the equilibria of the system is investigated by analyzing the characteristic equation and then the existence of fold and Neimark–Sacker bifurcations are verified. Subsequent to that, the direction and stability of the bifurcation are determined by using the normal form theory and center manifold theorem. Finally, some numerical simulations are carried out in order to support the results of mathematical analysis.     

Extracellular Matrix Proteins Involved in Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases and characterized by cognitive and memory impairments. Emerging evidence suggests that the extracellular matrix (ECM) in the brain plays an important role in the etiology of AD. It has been detected that the levels of ECM proteins have changed in the brains of AD patients and animal models. Some ECM components, for example, elastin and heparan sulfate proteoglycans, are considered to promote the upregulation of extracellular amyloid-beta (Aβ) proteins. In addition, collagen VI and laminin are shown to have interactions with Aβ peptides, which might lead to the clearance of those peptides. Thus, ECM proteins are involved in both amyloidosis and neuroprotection in the AD process. However, the molecular mechanism of neuronal ECM proteins on the pathophysiology of AD remains elusive. More investigation of ECM proteins with AD pathogenesis is needed, and this may lead to novel therapeutic strategies and biomarkers for AD.     

Predicted Singers' Vocal Fold Lengths and Voice Classification—A Study of X-Ray Morphological Measures

Students admitted to the solo singing education at the University of Music Dresden, Germany have been submitted to a detailed physical examination of a variety of factors with relevance to voice function since 1959. In the years 1959–1991, this scheme of examinations included X-ray profiles of the singers' vocal tracts. This material of 132 X-rays of voice professionals was used to investigate different laryngeal morphological measures and their relation to vocal fold length. Further, the study aimed to investigate if there are consistent anatomical differences between singers of different voice classifications. The study design used was a retrospective analysis. Vocal fold length could be measured in 29 of these singer subjects directly. These data showed a strong correlation with the anterior-posterior diameter of the subglottis and the trachea as well as with the distance from the anterior contour of the thyroid cartilage to the anterior contour of the spine. These relations were used in an attempt to predict the 132 singers' vocal fold lengths. The results revealed a clear covariation between predicted vocal fold length and voice classification. Anterior-posterior subglottic-tracheal diameter yielded mean vocal fold lengths of 14.9, 16.0, 16.6, 18.4, 19.5, and 20.9 mm for sopranos, mezzo-sopranos, altos, tenors, baritones, and basses, respectively. The data support the assumption that there are consistent anatomical laryngeal differences between singers of different voice classifications, which are of relevance to pitch range and timbre of the voice.     

Alzheimer's Disease: From Pathology to Therapeutic Approaches

Mind how you go : The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme β‐ and γ‐secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid β peptides, from which the disease‐defining deposits of plaque in the brains of Alzheimer's patients originates.

     

Fold optics path: an improvement for an atomic fountain

A fold optical path is utilized to capture and launch atoms in the atomic fountain.This improved technique reduces the laser power needed by 60 percent,facilitates suppression of the laser power fluctuations,and leads to a more simple and stable system.     

基于大鼠背部视窗显微观测的微血管网的三维重建

微循环是循环系统中最基层的结构和功能单位,它在保持人体正常生理功能中占有突出地位,许多疾病的发生也是从微循环开始. 因此,利用脊背视窗技术,并通过体视显微镜观察视窗内的血管结构, 进一步对所获血管图像进行一系列图像处理,得到了血管边界和中心线等结构信息. 同时,根据血管分叉处相贯线的信息确定分叉血管的连接方式. 在网格划分时,采用了改进的超限插值算法,构建了三维血管网的有限元网格模型,实现了对任意分支血管网的三维重建. 为微循环的体外实验和数值分析奠定基础.      

逆冲断层地震主震的突变理论分析

逆冲断层系统作准静态形变时的功、能量增量关系可以分解为关于体积应变能的功能增量关系和关于偏应力能的功能增量关系．采用突变理论方法对逆冲断层系统的偏应力功能量增量关系进行的分析表明:折迭突变模型展示的性状可对逆冲断层地震主震的发震条件、演化过程和若干震后特性作恰当描述．围岩的围压大,最大主应力大,逆冲潜断层面倾角小,围岩切向刚度与断层抗剪强度曲线软化段拐点处斜率的比值小, 则震时围岩弹性能释放量大、 震级高, 断层破裂半错距大, 围岩端面位移振幅也大．断层岩体破裂扩容和震时围岩体积应变能释放, 增强了前述效应．