具有可变形剪切连接件的连续复合梁的结构行为

对原型双跨复合梁的结构行为给出了详细的有限元研究．由于基本上认为剪切连接件是非刚性的,在高等有限元模型中采用弹簧单元可以将它们的非线性荷载一滑移性质考虑在内．对各种原型双跨复合梁进行了参数研究,并提出了主要的研究结果．主要的结构参数包括剪切连接件在正弯矩和负弯矩区域内的变形韧性和变形程度．总共比较和讨论了9个具有不同类型和剪切件数目的复合梁的结构行为,对目前的设计缺陷进行了鉴定．由于提出的有限元模型对详细调查复合梁的结构行为非常有效,有效地利用所提出的模型将对更具有改善结构精度和效率的细化设计准则的发展有帮助．     

Effect of aminoglutethimide on murine fetal hepatic erythroid colony formation

Pretreatment of pregnant mice with aminoglutethimide phosphate, an inhibitor of glucocorticoid synthesis, increases the content of fetal liver erythroid colony-forming cells (CFU-E), as assessed by the formation of erythroid colonies in vitro by fetal liver cells in plasma clots containing exogenous erythropoietin. In addition, the inability of aminoglutethimide to influence erythroid colony formation in vitro suggests that endogenous glucocorticoids exert a suppressive effect on the number of functional CFU-E in the fetal liver.     

A STUDY OF SEAM STRENGTH AND EXTENSIBILITY FOR PRESSURE GARMENTS

Pressure garments are functional garments designed for medical purposes and arc normally used under prolonged stress. The stress across seams is related to the size of the wearer and the fit and the garment, the more close fitting a garment, the greater stress is put on the seam. Since pressure garments are subjected to appreciable stress during wear, seams with the required strength and extensiblity are particular important. The seam type, stitch type, stitch density and thread strength are the main factors determining the strength and extensibility of a seam. In this paper, investigation of seam strength and extensibility are made on four types of seams which have been used for making pressure garments. Five different types of stitch densities and two sizes of sewing thread are used on each type of scam to be tested. The seaming conditions of the selected fabric are also examined.     

A primary determinant for lipoxygenase positional specificity

The three mammalian lipoxygenases are named according to the carbon position (5, 12 or 15) at which they catalyse the oxygenation of arachidonic acid; they are implicated in inflammatory disorders, for example 15-lipoxygenase is induced in atherosclerosis and can oxidize low-density lipoprotein to its atherogenic form. To identify what determines this positional specificity, we have exchanged conserved differences in the isoforms of 12- and 15-lipoxygenases. Substitution of methionine with valine at position 418 of human 15-lipoxygenase results in an enzyme that performs 12- and 15-lipoxygenation equally. This effect can be mimicked by incubating wild-type 15-lipoxygenase with a synthetically altered substrate which has its doubly allylic methylene carbons shifted by one carbon relative to arachidonic acid. Other mutations at the neighbouring amino acids 416 and 417 give an enzyme which performs 12- and 15-lipoxygenation in a ratio of 15:1. These results indicate that this region might position the substrate in the active site.     

双酚A对微小小环藻的毒性效应

以微小小环藻(Cyclotella caspia)为测试藻种,研究了不同浓度的双酚A对微小小环藻的急性毒性效应。在双酚A(4,6,8,10,12 mg/L)作用下,藻细胞生长受到不同程度的抑制;藻细胞叶绿素a含量随着双酚A浓度的增加呈下降趋势;藻细胞SOD活性随着双酚A浓度和作用时间的变化基本呈现为从诱导到抑制的动态过程;4~6 mg/L双酚A对藻细胞形态影响不大,8~12 mg/L双酚A可导致藻细胞不易分裂,细胞体积增大,细胞内含物增多,细胞器受到不同程度的破坏。     

Antibodies against metal chelates

Because monoclonal antibodies can recognize and bind to specific groups of atoms such as tumour antigens, they have promise for use in vivo as carriers of radionuclides, drugs or other appended molecules for diagnosis and treatment of disease. Attachment of metal ions to antibodies by means of bifunctional chelating agents can add the diverse nuclear, physical and chemical properties of the metallic elements to these specific binding proteins (ref. 4 and refs therein). With the ultimate aim of engineering probe-binding properties into the antibodies themselves, we have now prepared monoclonal antibodies against the EDTA chelate of indium. These antibodies show a remarkable preference for indium chelates; changing to another metal such as scandium or gallium can decrease the antibody-binding constant by more than three orders of magnitude. These antibodies also introduce a new degree of control over the biological distributions of chelated radionuclides, markedly altering their uptake in tumours and normal organs.     

Entrepreneurship Measurement and Comparison: Holistic Acceptability Global Entrepreneurship Index

Journal of Systems Science and Complexity - The Global Entrepreneurship and Development Institute annually publishes the Global Entrepreneurship Index (GEI) to show entrepreneurship of each...     

A general approach to single-nucleotide polymorphism discovery

Single-nucleotide polymorphisms (SNPs) are the most abundant form of human genetic variation and a resource for mapping complex genetic traits. The large volume of data produced by high-throughput sequencing projects is a rich and largely untapped source of SNPs (refs 2, 3, 4, 5). We present here a unified approach to the discovery of variations in genetic sequence data of arbitrary DNA sources. We propose to use the rapidly emerging genomic sequence as a template on which to layer often unmapped, fragmentary sequence data and to use base quality values to discern true allelic variations from sequencing errors. By taking advantage of the genomic sequence we are able to use simpler yet more accurate methods for sequence organization: fragment clustering, paralogue identification and multiple alignment. We analyse these sequences with a novel, Bayesian inference engine, POLYBAYES, to calculate the probability that a given site is polymorphic. Rigorous treatment of base quality permits completely automated evaluation of the full length of all sequences, without limitations on alignment depth. We demonstrate this approach by accurate SNP predictions in human ESTs aligned to finished and working-draft quality genomic sequences, a data set representative of the typical challenges of sequence-based SNP discovery.