Programming the Grid: Distributed Software Components, P2P and Grid Web Services for Scientific Applications

Computational Grids [17,25] have become an important asset in large-scale scientific and engineering research. By providing a set of services that allow a widely distributed collection of resources to be tied together into a relatively seamless computing framework, teams of researchers can collaborate to solve problems that they could not have attempted before. Unfortunately the task of building Grid applications remains extremely difficult because there are few tools available to support developers. To build reliable and re-usable Grid applications, programmers must be equipped with a programming framework that hides the details of most Grid services and allows the developer a consistent, non-complex model in which applications can be composed from well tested, reliable sub-units. This paper describes experiences with using a software component framework for building Grid applications. The framework, which is based on the DOE Common Component Architecture (CCA) [1,2,3,8], allows individual components to export function/service interfaces that can be remotely invoked by other components. The framework also provides a simple messaging/event system for asynchronous notification between application components. The paper also describes how the emerging Web-services [52] model fits with a component-oriented application design philosophy. To illustrate the connection between Web services and Grid application programming we describe a simple design pattern for application factory services which can be used to simplify the task of building reliable Grid programs. Finally we address several issues of Grid programming that better understood from the perspective of Peer-to-Peer (P2P) systems. In particular we describe how models for collaboration and resource sharing fit well with many Grid application scenarios.     

Sitosteryl-β-D-(6-O-fattyacyl)-glucopyranosides from the crude phosphatides of maize [1]

A new component of the crude phosphatides of Zea Mays Linn. has been identified as sitosteryl-β-D-(6-O-fattyacyl)-glucopyranoside (I). Its gross structure, as a monoester of sitosteryl-β-D-glucoside, was derived from a study of the products formed on methanolysis and on acid hydrolysis. The location of the fatty ester was established by comparison of the proton chemical shift for H₂C-6 in its tribenzoyl derivative with the chemical shifts for the corresponding protons in model benzoyl, acetyl and mixed benzoyl-acetyl derivatives of sitosteryl-β-D-glucopyranoside. The structure was confirmed by comparison, especially of optical rotation data, with a sample of sitosteryl-β-D-(6-O-stearoyl)-glucopyranoside prepared by synthesis. The [α]_D values for the natural (?45°) and the synthetic sample (?46.5°) are practically identical. Further there is good agreement between the molar rotation difference (ΔM_D) between (I) and its parent sitosterylglucoside and between the synthetic pair of glucoside and its ester.The approach to structure followed, in particular the use of ΔM_D comparisons, and the optical rotation data recorded in this paper, provide simple and convenient means for establishing the structure of other natural esterified sterol glycosides.     

Virulence ofEscherichia coli isolated from raw meat,food handlers and equipment of meat shops

Of 101Escherichia coli isolates from raw meat, food handlers and equipment 24.8% showed enterotoxigenicity, 22.7% surface hydrophobicity and there was a high incidence of resistance towards metal ions such as mercury, cadmium and silver. Only 6% of the strains were colicin producers. Significant statistical correlation was observed between enterotoxin production and cadmium and mercury ion resistance.

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Résumé Center une souches d'Escherichia coli ont été, isolées de viandes crues, de manutantionneurs de nourriture et d'equipement de boucherie. Elles exhibent une enterotoxigénécité à concurrence de 24.8%, une hydrophobicité de surface à concurrence de 22.7%. Il y a une grande fréquence de résistance vis-à-vis d'ions métalliques comme le mercure, le cadmium et l'argent. A peine 6% des souches sont productrices de colicine. Il y a une corrélation significative sur le plan statistique entre la production d'enterotoxines et la résistance aux ions cadmium et mercure.

     

Digalactosylceramide is the receptor for staphylococcal enterotoxin-B in human kidney proximal tubular cells

We have characterized a glycosphingolipid (GSL) receptor forStaphylococcus enterotoxin-B (SEB) in cultured human kidneyproximal tubular (PT) cells. Solid-phase binding of [¹²⁵I]SEBto the GSL receptor was concentration dependent and was notdisplaceable by two structurally related toxins, such as staphylococcalenterotoxin-A and toxic shock syndrome toxin-1. Rat kidney cellsdid not bind [¹²⁵I]SEB. However, when the rat kidney cells werepre-incubated with digalactosylceramide, there was a concentration-dependentbinding of [¹²⁵I]SEB. Trimethylsilyl derivatization of methylglycosides, followed by gas-liquid chromatography-mass spectrometry(GC-MS), revealed that galactose was the major sugar componentof this putative receptor GSL. The sphingosines present in thisGSL were d18:2, d22:2 and d23:0; the fatty acids present werepalmitate, oleate and stearate. Permethvlation of alditol acetatesand GC-MS revealed two predominant sugars, namely 2, 3, 4 and6 tetramethylgalactital and 2, 3 and 6 trimethylgalactital.The GSL receptor for SEB was sensitive to a-galactosidase, andresistant to (3-galactosidase and fi-glucosidase. Taken together,our studies reveal that the tentative structure of the receptorfor SEB in human kidney PT cells is CerGal