Structure and function in the cerebral ganglion

Evidence is reviewed to evaluate whether the term "brain is justified in referring to the snail's cerebral ganglion. The focus of the review is terrestrial species, with particular attention given to the genus Helix. In accordance with a standard definition of "brain, the cerebral ganglion is found to be differentiated both structurally and functionally. It receives convergent sensory inputs from a variety of anterior sensory organs plus the posterior body wall. Its outputs comprise motor commands directed towards anterior muscle systems, e.g., the tentacles and the penis, as well as premotor commands directed towards executory centers in other ganglia, e.g., the buccal, visceral, and pedal ganglia. Of the three major divisions in the ganglion, the procerebrum and the mesocerebrum are the most differentiated, whereas the metacerebrum is the least differentiated. The specializations of the procerebrum for olfactory functions, and the mesocerebrum for reproductive functions, reflect the importance of adaptations for feeding and mating in the evolution of the Gastropoda.     

Structure and function of endothelial caveolae

Caveolae are spherical invaginations of the plasma membrane and associated vesicles that are found at high surface densities in most cells, endothelia included. Their structural framework has been shown to consist of oligomerized caveolin molecules interacting with cholesterol and sphingolipids. Caveolae have been involved in many cellular functions such as endocytosis, signal transduction, mechano-transduction, potocytosis, and cholesterol trafficking. Some confusion still persists in the field with respect to the relationship between caveolae and the lipid rafts, which have been involved in many of the above functions. In addition to all these, endothelial caveolae have been involved in capillary permeability by their participation in the process of transcytosis. This short review will focus on their structure and components, methods used to determine these components, and the role of caveolae in the transendothelial exchanges between blood plasma and the interstitial fluid.     

Structure and function of the bat superior olivary complex

The superior olivary complex (SOC) is a mammalian auditory brainstem structure that contains several nuclei. Some of them are part of the ascending system projecting to higher auditory centers, others belong to the descending system projecting to the cochlear nuclei or the cochlea itself. The main nuclei of the ascending system, the lateral and medial superior olive (LSO, MSO), as well as the lateral and medial nuclei of the trapezoid body (LNTB, MNTB), have been traditionally associated with sound localization. Here we review the results of recent studies on the main SOC nuclei in echolocating bats. These studies suggest that some SOC structures and functions are highly conserved across mammals (e.g., the LSO, which is associated with interaural intensity difference processing), while others are phylogenetically highly variable in both form and function (e.g., the MSO, traditionally associated with interaural time difference processing). For the MSO, these variations indicate that we should broaden our view regarding what functions the MSO might participate in, since its function in echolocation seems to lie in the context of pattern recognition rather than sound localization. Furthermore, across bat species, variations in the form and physiology of the MSO can be linked to specific behavioral adaptations associated with different echolocation strategies. Finally, the comparative approach, including auditory specialists such as bats, helps us to reach a more comprehensive view of the functional anatomy of auditory structures that are still poorly understood, like the nucleus of the central acoustic tract (NCAT).     

Structure and function of the extracellular matrix of anuran eggs

The extracellular matrix (ECM) surrounding the anuran egg is composed of jelly coat layers, an envelope, and the perivitelline space, which separates the envelope from the egg plasma membrane. Both the jelly coat layers and egg envelopes are required for fertilization in anurans. This paper reviews the current understanding of the structure-function relations of the ECM, with emphasis on the egg envelope. The fibrous egg envelope exists in four related forms. The envelope forms differ in their ultrastructures, macromolecular compositions, and cellular functions. After the oocyte is released from the ovary, conversion of one envelope form to another is brought about by factors secreted by the oviduct prior to fertilization and by factors released from the egg in the sperm-triggered cortical reaction. An additional extracellular matrix structure, located in the perivitelline space, has recently been identified in Xenopus laevis, as well as a previously undescribed reorganization of envelope fibers occurring at fertilization. The molecular changes in the ECM glycoproteins (limited proteolysis, lectin-ligand binding, and conformational changes) and the oviductal and egg macromolecules responsible for the conversion of envelope forms are discussed. New experimental evidence that supports the lectin-ligand hypothesis for the formation of the fertilization layer is presented. It is proposed that the molecular changes in the ECM are responsible for the ultrastructural alterations of the ECM and for modifications of the fertilization and developmental functions of the anuran egg ECM.     

Peroxisome biogenesis and degradation in yeast: a structure/function analysis

In yeast, peroxisomes are the site of specific catabolic pathways that characteristically include hydrogen peroxide producing oxidases and catalase. During the last 10 years, much progress has been made in unravelling the molecular mechanisms involved in the biogenesis of this organelle. At present, 23 different genes (PEX genes) have been identified that are involved in different aspects of peroxisome biogenesis (e.g., proliferation, formation of the peroxisomal membrane, import of matrix proteins). The principles of peroxisome degradation are still much less understood. Recently, the first yeast mutants affected in this process have become available and used to clone corresponding genes by functional complementation. In this paper, an overview is presented of the research on yeast peroxisomes, focusing on recent achievements in the molecular aspects of peroxisome development, function, and turnover.     

Functions of ULK1 in autophagy and non-autophagy pathways and its implications in human physiology and disease

ULK1 (unc-51 like autophagy activating kinase 1), a mammalian serine/threonine kinase, is a key component ofautophagy initiation complex and helps to induce all types of autophagy. Canonical autophagy is a process in which,through the interactions of a series of autophagy-related proteins, damaged organelles or misfolded proteins areengulfed by autophagosomes and then merged with lysosomes to be degraded. Thus, canonical autophagy is animportant constituent part of the cellular “quality control.” Besides, accumulating evidence indicates that ULK1 exertsautophagy-independent effects in a cell-specific manner. For example, ULK1 facilitates neurite elongation through theregulation of endoplasmic reticulum (ER)–Golgi trafficking in neurons, stimulates phosphopentose pathway to helpNADPH (nicotinamide adenine dinucleotide phosphate hydrogen) production, and acts as a duplex regulator in typeI IFN (type I interferon) induced innate immune response. Considering the importance and diversity of ULK1 invarious biological processes, this review aims to present a comprehensive overview of autophagy and non-autophagyrelated functions of ULK1 in a variety of human physiological, pathological, and disease processes.     

Foliar micromorphology and its role in identification of the Apocynaceae taxa

In the present study, we evaluate the importance of foliar epidermal micromorphological characteristics of Apocyanaceae for accurate identification and classification. The species were collected from the University of Peshawar's main campus in the spring season to observe its qualitative and quantitative features. The length and width of guard cells, stomatal pore and subsidiary cells, trichomes, and crypts on both sides of the leaf were examined. Many species were observed to be hypostomatic. Plumeria rubra, Raulfia serpentine, Thevetia peruviana, Trachelospermum lucidum, Alstonia scholaris, and Catharanthus roseus demonstrated hypostomatic leaves. Nearly all the investigated species had anisocytic type of stomata only or in combination with other types of stomata on the upper and lower epidermis. Carissa carandas had anomocytic, anisocytic, and cyclocytic type of stomata on the upper epidermis, and the lower epidermis showed variations in stomatal type, such as anomocytic, stephanocytic, brachyparacytic, and hemiparacytic. Nerium oleander had no specific shape of stomata but showed stomatal crypts in which the stomata were enclosed inside many trichomes. The taxonomic key based on stomatal types, epidermal cells, stomatal index value, and statistical analysis, along with the variations in the epidermal cells, shows the link between the selected plants species, which will provide a baseline for future anatomical studies. This study highlights many undocumented micromorphological characteristics. The anatomical characteristics observed in this study will be helpful for taxonomic identification and species delimitation of the family Apocynaceae.     

屏蔽技术在结构设计中的应用

对舰载时统站的电磁兼容性结构设计进行了研究。通过对舰载时统站结构的屏蔽效能的计算，对屏蔽体材料的选择进行了优化。在结构设计中，采用国内外新技术、新工艺，提高了缝隙的屏蔽效能，解决了孔洞泄露与能风散热之间的矛盾。经中国船舶工业总公司电磁兼容性检测中心EMC考核试验，该舰载时统站的电磁兼容性达到了国家标准，在国内处于领先水平。     

Bacterial proteomics and its role in antibacterial drug discovery

Gene-expression profiling technologies in general, and proteomic technologies in particular have proven extremely useful to study the physiological response of bacterial cells to various environmental stress conditions. Complex protein toolkits coordinated by sophisticated regulatory networks have evolved to accommodate bacterial survival under ever-present stress conditions such as varying temperatures, nutrient availability, or antibiotics produced by other microorganisms that compete for habitat. In the last decades, application of man-made antibacterial agents resulted in additional bacterial exposure to antibiotic stress. Whereas the targeted use of antibiotics has remarkably reduced human suffering from infectious diseases, the ever-increasing emergence of bacteria that are resistant to antibiotics has led to an urgent need for novel antibiotic strategies. The intent of this review is to present an overview of the major achievements of proteomic approaches to study adaptation networks that are crucial for bacterial survival with a special emphasis on the stress induced by antibiotic treatment. A further focus will be the review of the, so far few, published efforts to exploit the knowledge derived from bacterial proteomic studies directly for the antibacterial drug-discovery process.     

机械可靠性及其在雷达结构设计中的应用

阐述了机械可靠性设计及其在雷达结构设计中的应用,首先介绍了机械可靠性设计特点,阐述了结构可靠度的概念及其函数表达。接着介绍了复杂结构的可靠性分析方法,重点探讨了基于ANSYS的结构可靠性计算基本思路和方法,应用ANSYS的概率分析模块对某雷达升降杆进行可靠性计算分析,得出了一些有利于提高其可靠性的结论,该方法和结论也适合于雷达上其它结构。     

多层前向神经网络的设计及在结构设计中的应用

本文介绍了工程中应用较多的多层前向神经网络(也称BP网络)的设计,简要介绍了多层前向神经网络的结构,介绍了为神经网络选择训练样本的“超立方体”法,并给出了实例,证明了“超立方体”法的有效性。     

糖尿病消化不良患者的自主神经功能及其对近端胃功能影响

目的 :探讨糖尿病消化不良患者的自主神经功能及其与近端胃功能的相关性。方法:选取2010年3月²012年7月间于我院消化科就诊并出现胃肠道症状的糖尿病患者40例以及健康成人30例,通过标准心血管反射试验、水负荷试验测定自主神经功能及近端胃功能,对比分析糖尿病消化不良患者的自主神经功能及其对近端胃功能的影响。结果 :经过标准心血管反射试验发现,糖尿病消化不良患者的副交感神经、交感神经、自主神经的功能评分与对照组相比,分值显著升高(P均<0.05),以副交感神经功能受损情况更为严重(P<0.01);糖尿病消化不良患者中,自主神经正常仅3例,自主神经早期累及17例,明确累及20例,异常的比例达92.5%,与对照组相比,自主神经功能异常人数显著增加;糖尿病消化不良患者的阈值饮水量、饱足饮水量与对照组相比显著减少;糖尿病消化不良患者饱足饮水后,其近端胃面积和周长均变小,与对照组相比差异具有统计学意义(P<0.05),而远端胃面积和周长变化增大,但与对照组相比无统计学意义(P>0.05);糖尿病消化不良患者的交感神经功能评分与患者阈值饮水量和饱足饮水量时近端胃的横截面周长的变化呈负相关性(r=-0.574,P<0.01)。结论 :糖尿病消化不良患者的自主神经功能受到损伤,与患者的近端胃功能存在一定相关性,但二者之间的相互影响有待进一步研究。     

Friction in textile fibers and its role in fiber processing

Textile fibers are characterized by many parameters, used by both researchers and industrial users. Many studies focus on the effect of fiber length, fineness, maturity (only for cotton), tensile properties, etc. on the properties of intermediate products and yarns. Contrary, few studies concerning the fiber surface properties, especially the inter-fiber friction, appear in the scientific literature. A new and simple device is designed and used in this. It enables the measurement of inter-fiber friction force during the dissociation of an ordinary sliver. Contrary to what has previously been mentioned in the scientific literature, the study of a set of different cottons shows that the inter-fiber friction seems to obey the Amontons’ law rather than a more complex power law model. The calculated inter-fiber friction coefficient helps to differentiate the different types of cotton and to bring to the fore the non-negligible effect of the friction on yarn irregularity and imperfections, affecting the yarn tenacity indirectly. Meanwhile, this work has revealed a curious grouping of different types of cotton, which is not observed before. This phenomenon is undoubtedly due to the surface properties of fibers.     

旋转给料阀的结构及特点

介绍了PTA、聚丙烯、聚乙烯等装置应用的定量输送粉料的旋转给料阀性能结构特点，技术改进的方案和实际应用。针对其结构特点在密封和转子与壳体的间隙等方面做了改进工作。     

动力学相似理论及在结构振动分析中的应用研究评述与展望

相似试验模型在大型结构振动与冲击试验研究中起到重要作用。综述动力学相似理论在结构动力学相似试验模型设计中的应用研究进展与发展趋势,并引述大量文献。总结动力学相似理论在多个领域的结构振动与冲击问题分析中的主要成果,包括动力学相似理论在海洋结构、土建结构及大型动力装备动力学相似试验模型设计中的应用,复合材料结构的动力学相似设计方法,以及转子系统的动力学相似试验模型设计方法。介绍动力学相似理论的重要研究进展情况,如畸变试验模型的设计及修正方法、动力学相似模型的试验验证。讨论动力学相似理论在结构振动与冲击研究中存在的主要问题并做出展望。     

自相关的除噪作用及其在工程中的应用

自相关除噪有其内在的数学原理.从理论上讲,自相关除噪是比较彻底的;在实践中,这种方法简便易行,尤其在提取信号的低频特征中,有着象功率谱这样的常用方法所不能比拟的优越性.本文通过提取某钢铁公司轧钢机信号的特征频率,展示了自相关处理的优势.同时对比自相关处理,阐述了功率谱在这方面所表现出的局限性及其根源.     

三角函数逼近算法及其在光学条纹图像分析中的应用

三角函数与反三角函数作为基本初等函数,在光学条纹图像分析中有着广泛的应用。在某些特定情况下,如硬件计算或要求快速计算时,可以通过逼近函数来计算其近似值。现讨论三角函数及反三角函数的最佳逼近方法。基于∞范数,选择特定区间推导函数的最佳逼近多项式,给出了多项式的系数与最大逼近误差;再利用三角恒等式将其推广至函数的整个定义区间,得到了各三角函数与反三角函数的分段逼近多项式。并且将其结果用于条纹图像的分析,以实验证明了所述方法的有效性。     

加工中心结构、形态分析及其仿真设计

本文详细介绍了加工中心的结构和形态,并且对加工中心的结构提出了改进措施。然后,以卧式加工中心为例,通过对比,阐述T形态结构的优势。最后,为了提高加工中心的设计水平,提出了运用UG三维CAD/CAM软件,进行加工中心的虚拟仿真设计,并探讨了具体的设计思路和方法。     

REAC衬管的流体仿真分析及其结构优化

针对国产REA衬管最为常见的冲蚀失效，对冲蚀现象最为严重的衬管尾部进行多相流仿真分析。通过仿真分析出衬管冲蚀减薄的位置及其因素，并提出具体的结构优化措施分析。     

硬质聚氨酯泡沫塑料芯材与夹层结构的研究

研究了发泡原料选择和发泡工艺参数对硬质聚氨酯泡沫塑料的性能及质量的影响,指出发泡填充系数和密度是决定泡沫芯材与夹层结构性能及应用领域的关键因素,说明了聚氨酯泡沫夹层结构具有较好的环境协调性。结果表明,泡沫芯材密度的增加可明显改善芯材的力学性能,采用聚醚组料、体积填充系数为3～4时,芯材综合性能较佳。