Nature of the motor element in electrokinetic shape changes of cochlear outer hair cells

It is the prevailing notion that cochlear outer hair cells function as mechanical effectors as well as sensory receptors. Electrically induced changes in the shape of mammalian outer hair cells, studied in vitro, are commonly assumed to represent an aspect of their effector process that may occur in vivo. The nature of the motile process is obscure, even though none of the established cellular motors can be involved. Although it is known that the motile response is under voltage control, it is uncertain whether the stimulus is a drop in the voltage along the long axis of the cell or variation in the transmembrane potential. We have now performed experiments with cells partitioned in differing degrees between two chambers. Applied voltage stimulates the cell membrane segments in opposite polarity to an amount dependent on the partitioning. The findings show, in accordance with previous suggestions, that the driving stimulus is a local transmembrane voltage drop and that the cellular motor consists of many independent elements, distributed along the cell membrane and its associated cortical structures. We further show that the primary action of the motor elements is along the longitudinal dimension of the cell without necessarily involving changes in intracellular hydrostatic pressure. This establishes the outer hair cell motor as unique among mechanisms that control cell shape.     

Evaluation of cement degradation induced by the metabolic products of two fungal strains

Summary During their metabolism, microorganisms can produce acids able to bring about the degradation of cement. Two acid-producing alkalophilic fungal strains have been isolated from soil, a strain ofAspergillus niger which produces gluconic and oxalic acid and ofMycelia sterila which produces gluconic and malic acid. After eleven months of contact the acids produced byAspergillus dissolved portlandite with a low leaching of calcium, increased the cement porosity by 11.4%, and reduced the bending strength by 78%. The second strain is responsible for a significant dissolution of portlandite with a leaching of calcium of 4.2% of the initial content, an increase of the porosity of 11%, and a loss of the bending strength of 62%. Direct contact of mycelia with the cement surface is not necessary for effective dissolution to take place. Low pH and a high temperature favor the the production of acids.     

Homology of a 150K cytoplasmic dynein-associated polypeptide with the Drosophila gene Glued

Cytoplasmic dynein is a microtubule-activated ATPase which produces force towards the minus ends of microtubules. It is thought to be responsible for retrograde axonal transport and other aspects of organelle motility and may have a role in the poleward movement of mitotic chromosomes. Cytoplasmic dynein is an oligomeric complex of two catalytic heavy chains and a number of accessory subunits. We now report the cloning and sequencing of a complementary DNA for one of these species, a cytoplasmic dynein-associated polypeptide of relative molecular mass 150,000 (Mr 150K). A full-length cDNA was found to contain an open reading frame of 4.0 kilobases, which is predicted to encode a polypeptide of Mr 145K. It has extensive homology with the product of the Drosophila gene Glued, which encodes a polypeptide of Mr 148K. The Glued mutation is dominant, with pleiotropic developmental defects in heterozygotes and an embryonic lethal phenotype in homozygotes. As dominant mutations may involve disruption of normal protein-protein interactions, the Glued mutation should provide insight into the mode of action of cytoplasmic dynein in vivo.     

An HTLV-III peptide produced by recombinant DNA is immunoreactive with sera from patients with AIDS

Human T-cell lymphotropic retrovirus type III (HTLV-III), also called lymphadenopathy-associated virus (LAV), has been identified as the aetiological agent of acquired immune deficiency syndrome (AIDS). The sera of most patients with AIDS or AIDS-related complexes, and of asymptomatic individuals infected with HTLV-III, contain antibodies against antigens of HTLV-III. The characterization of these antibodies and their corresponding viral antigens is important not only for understanding immunity against HTLV-III and the pathology of AIDS, but also for the development of diagnostic methods and preventive vaccine for AIDS. Following the successful establishment of a long-term T-cell line permissive for HTLV-III replication, large quantities of virus have been produced, facilitating the purification of viral proteins and the development of mouse monoclonal antibodies against several viral antigens. More recently, the structure of HTLV-III proviral DNA has been elucidated. We now report the production, by genetic engineering methods, of a peptide encoded by a gene segment of HTLV-III. A 1.1-kilobase (kb) EcoRI DNA segment from an isolate of HTLV-III was inserted into a lpp and lac promoter-coupled expression vector, pIN-III-ompA. Escherichia coli transformants of this plasmid produced a peptide of relative molecular mass (Mr) 15,000 (15K) which was strongly immunoreactive with anti-HTLV-III antibodies present in sera from AIDS patients. Lysates of the clones expressing this 15K peptide inhibited the reactivity of the p31 virion protein with AIDS sera, suggesting that it is a fragment of the viral p31 protein. The peptide reacted with sera from all 20 AIDS patients but none of the 8 normal controls tested. These results suggest that the peptide may be useful for detecting anti-HTLV-III antibodies in blood samples.     

顺序统计滤波能量驱动的鲁棒快速图像分割

为了提升图像分割的速度与初始轮廓和参数鲁棒性,提出了一种基于有序统计滤波能量驱动的鲁棒主动轮廓模型。首先用顺序统计滤波的边力函数来代替传统的数据拟合,进一步引入边力函数能量泛函快速自适应地吸引曲线向目标的边界演化。为了有效地调节水平集函数,利用优化后的长度项对曲线进行平滑和缩短,并通过标准梯度下降法将能量泛函最小化。最后实验结果表明提出的方法能够更加快速、准确地分割图像,并且对初始轮廓和参数具有较强的鲁棒性。     

火灾报警系统的研究

介绍了火灾报警系统的硬件设置与软件设计原理，讨论了该系统安装调试过程中的有关技术问题，阐述了对该系统进行的模拟联动试验，证明该系统的技术是先进的，工作是可靠的，每个工作环节都准确无误。     

图书馆的人力资源建设

分析了人才资源与图书馆生存和发展的关系，指出：应从发现人才、重用人才和培养人才3个方面建立人才培养机制；同时强调只有加强领导班子建设才能充分发挥人才的作用。