Two-Dimensional protein map of Saccharomyces cerevisiae: Construction of a gene–protein index

This publication marks the beginning of the construction of a gene–protein index that relates proteins which are resolved on the two-dimensional protein map of Saccharomyces cerevisiae with their corresponding genes. We report the identification of 36 novel polypeptide spots on the yeast protein map. They correspond to the products of 26 genes. Together with the polypeptide spots previously identified, this raises to 41 the number of genes whose products have been identified on the protein map. The proteins identified here are concerned with four major areas of yeast cellular physiology: carbon metabolism, heat shock, amino acid biosynthesis and purine biosynthesis. Given the molecular weight and isoelectric point of the identified proteins, and the codon-usage bias of the corresponding genes, it can be estimated that 25 to 35% of all the soluble yeast proteins are detectable under the labelling and running gel conditions used in this study.     

一步法成型保温管聚氨酯泡沫层力学性能研究

文章对采用"一步法"成型工艺生产的保温管取其聚氨酯泡沫保温层剖面不同位置的试样进行密度和力学性能研究,探讨了保温层试样性能的差异。采用扫描电子显微镜观察了初始泡孔结构,发现低密度聚氨酯泡沫的泡孔结构为多面体,泡孔之间以薄膜相隔离;高密度泡沫的泡孔结构呈球形,气泡之间相互孤立;中密度泡沫的泡孔以球形和多面体形状混合存在。     

法向压缩载荷对II型裂纹扩展的影响规律研究

压剪共同作用下裂纹是地下岩体中广泛存在的,为了研究法向压缩载荷对剪切型即II型裂纹扩展的影响规律,利用砂岩制作了单边裂纹试件,通过岩石剪切实验系统对不同法向压缩载荷作用下的裂纹进行了剪切实验研究,结果表明法向压缩载荷对裂纹的起裂及扩展起到抑制作用,随着裂纹法线压缩载荷的增大,裂纹起裂角逐渐减小;同时,得出法向压缩载荷与II型裂纹极限应力强度因子之间的关系,随着法向压缩载荷增大,岩石II型裂纹极限应力强度因子也随之增大。运用ABAQUS模拟软件,对不同压缩载荷作用下压剪裂纹的扩展进行模拟研究,得出了裂纹尖端II型应力强度因子随压缩载荷的变化规律。     

Grid-based Data Access to Nucleotide Sequence Database

The International Nucleotide Sequence Database Collaboration (INSDC) exchanges sequence data on a daily basis across its three member organizations in the USA, UK and Japan. This paper studies how this sequence database in MySQL can best take advantage of the increased transfer bandwidth of a Grid-optimized data communication protocol. Within the context of the UK Government Project Grid-oriented Storage (GOS) and the EC Project EuroAsiaGrid, GOS File System (GOS-FS) has been developed in our lab, which melds distributed file system technology with high performance data transfer techniques to meet the needs of WAN/Grid-based virtual organizations. A real-world test shows that the INSDC sequence database backing up operation, mysqldump, over the GOS-FS protocol beats those over the classic NFS protocol by 6 times over the link between Cambridge and Tokyo. Best of all, the multi-streamed GOS-FS protocol remains fully compatible with existing IP infrastructures.     

关于标准铂电阻温度计的检定规程的修订

本文介绍标准铂电阻温度计规程修订的原因、依据和修订的内容以及要达到的目标。     

基于F18高精密电桥的温度计自动测量检定系统

本文介绍了在F18高精密电桥基础上,利用V isual Basic6.0,Access2000、M icrosoftExcel及水晶报表为主要开发工具,以W indows为开发平台设计了一套完善的温度计自动测量检定系统。实验验证该系统提高了测量准确度及温度计检定的工作效率。     

Identification of proteins of the yeast protein map using genetically manipulated strains and peptide-mass fingerprinting

In this study we used genetically manipulated strains in order to identify polypeptide spots of the protein map of Saccharomyces cerevisiae. Thirty-two novel polypeptide spots were identified using this strategy. They corresponded to the product of 23 different genes. We also explored the possibilities of using peptide-mass fingerprinting for the identification of proteins separated on our gels. According to this strategy, proteins contained in spots are digested with trypsin and the masses of generated peptides are determined by matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). The peptide masses are then used to search a yeast protein database for proteins that match the experimental data. Application of this strategy to previously identified polypeptide spots gave evidence of the feasibility of this approach. We also report predictions on the identities of nine unknown spots using MALDI-MS.     

Analysis of flow transfer times in IEEE 802.11 wireless LANs

In this paper we present an integrated packet/flow level modelling approach for analysing flow throughputs and transfer times inieee 802.11wlans. It captures the statistical characteristics of the transmission of individual packets at themac layer and takes into account the system dynamics due to the initiation and completion of data flow transfers. In particular, at the flow level the system is modelled by a processor sharing type of queue, reflecting theieee 802.11mac design principle of distributing the transmission capacity fairly among the active flows. The integrated packet/flow level model is analytically tractable and yields a simple approximation for the throughput and flow transfer time. Extensive simulations show that the approximation is very accurate for a wide range of parameter settings. In addition, the simulation study confirms the attractive property following from our approximation that the expected flow transfer delay is insensitive to the flow size distribution (apart from its mean).     

Eight Times Acceleration of Geospatial Data Archiving and Distribution on the Grids

A grid-powered Web Geographical Information Science (GIS)/Web Processing Service (WPS) system has been developed for archiving and distributing large volumes of geospatial data. However, users, WPS servers, and data resources are always distributed across different locations, attempting to access and archive geospatial data from a GIS survey via conventional Hypertext Transport Protocol, Network File System Protocol, and File Transfer Protocol, which often encounters long waits and frustration in wide area network (WAN) environments. To provide a ldquolocal-likerdquo performance, a WAN/grid-optimized protocol known as ldquoGridJetrdquo developed at our lab was used as the underlying engine between WPS servers and clients, which utilizes a wide range of technologies including the one of paralleling the remote file access. No change in the way of using software is required since the multistreamed GridJet protocol remains fully compatible with the existing IP infrastructures. Our recent progress includes a real-world test that PyWPS and Google Earth over the GridJet protocol beat those over the classic ones by a factor of two to eight, where the distribution/archiving distance is over 10 000 km.     

Performance Analysis of Fair Channel Sharing Policies in an Integrated Cellular Voice/Data Network

We study channel sharing in an integrated cellular voice/data network with a finite queue for data call requests that cannot be served immediately upon arrival. Using analytical techniques, a comparison of different fair channel sharing policies is made. As a main result, a closed-form expression is derived for the expected sojourn time (waiting time plus transfer time) of a data call, conditional on its size, indicating that the sojourn time is proportional to the call size. This attractive proportionality result establishes an additional fairness property for the channel sharing policies proposed in the paper. Additionally, as a valuable intermediate result, the conditional expected sojourn time of an admitted data call is obtained, given the system state at arrival, which may serve as an appreciated feedback information service to the data source. An extensive numerical study is included to compare the proposed policies and to obtain insight in the performance effects of the various system and policy parameters.