The distributed ASCI supercomputer project

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project

Estimating the permeability of reservoir sandstones using image analysis of pore structure

In this thesis, a method is developed for predicting the permeabilities of a core using only a small number of SEM images, without resorting to computationally intensive procedures. The pore structure is idealised as consisting of a cubic network of pore tubes having an arbitrary distribution of cross-sectional areas and shapes. The areas and perimeters of the individual pores are estimated from image analysis of scanning electron micrographs of thin sections, with appropriate stereological corrections introduced to infer the true cross sections of the pores. Effective medium theory is used to find the effective single-tube conductance, based on the measured distribution of individual conductances, thereby allowing a prediction of the permeability. The methodology has been applied to several reservoir sandstones from the North Sea, and also an outcrop sample from Cumbria, UK, yielding predictions that fall within a factor of two of the laboratory measurements in most cases. The procedure, although based on Kirkpatrick's intrinsically isotropic effectivemedium approximation, is not only capable of yielding reasonably accurate estimates of the permeabilities, but also gives a qualitatively correct indication of the anisotropy ratio. It also found that the use of an Bernasconi's anisotropic effective-medium approximation does not lead to a systematic improvement in the results, perhaps because the samples used in this study were insufficiently anisotropic for the approaches to yield different results. The validity of the effective medium approximation was also tested against exact pore network calculations. For the rocks examined in this study, with pore conductance distributions having log-variances less than 3, the effective medium approximation was found to be accurate to within a few percent.Open Acces

From diversity to convergence : British computer networks and the Internet, 1970-1995

The Internet's success in the 21st century has encouraged analysts to investigate the origin of this network. Much of this literature adopts a teleological approach. Works often begin by discussing the invention of packet switching, describe the design and development of the ARPANET, and then examine how this network evolved into the Internet. Although the ARPANET was a seminal computer network, these accounts usually only briefly consider the many other diverse networks that existed. In addition, apart from momentary asides to alternative internetworking solutions, such as the Open Systems Interconnection (OSI) seven-layer reference model, this literature concentrates exclusively on the ARPANET, the Internet, and the World Wide Web. While focusing on these subjects is important and therefore justified, it can leave the reader with the impression that the world of networking started with the ARPANET and ended with the Internet. This thesis is an attempt to help correct this misconception. This thesis analyses the evolution of British computer networks and the Internet between the years 1970 and 1995. After an introduction in Chapter 1, the thesis analyses several networks. In Chapters 2 and 3, the focus is on academic networks, especially JANET and SuperJANET. Attention moves to videotex networks in Chapter 4, specifically Prestel, and in Chapter 5, the dissertation examines electronic mail networks such as Telecom Gold and Cable & Wireless Easylink. Chapter 6 considers online services, including CompuServe, American Online, and the Microsoft Network, and the thesis ends with a conclusion in Chapter 7. All of the networks discussed used protocols that were incompatible with each other which limited the utility of the networks for their users. Although it was possible that OSI or another solution could have solved this problem, the Internet's protocols achieved this objective. This thesis shows how the networks converged around TCP/IP

Isolation and Analysis of Characteristic Compounds from Herbal and Plant Extracts

Herbal and plant extracts show diverse activities and have been used for centuries as natural medicines for many health problems and diseases. Through the isolation and analysis of the compounds in the extracts, it is possible to understand why the extracts exhibit those activities, as well as the chemical metabolism of compounds that occur in plants and herbs. Recently, there have been increasing attempts to develop herbal and plant extracts into functional foods and drugs, but the legal requirements are becoming stricter. We need sophisticatedly defined extracts through the isolation and analysis of compounds comprising them in order to meet the legal requirements and to pursue quality control strategies in the production of functional foods and drugs. This Special Issue Book compiled the 15 recent research and review articles that highlight the isolation, profiling, and analysis of compounds in herbal and plant extracts, as well as quality control and standardized processing strategies for extracts with characteristic compounds

Echinoderms Metabolites: Structure, Functions and Biomedical Perspectives

The materials published in the Special Issue reflect the real diversity of echinoderm metabolites and cover most of their specific classes and biomedical potential as antioxidant, antiviral, anticancer, and even anticoagulant preparations. The metabolites include sea urchin naphtoquinoid pigments and their semi-synthetic derivatives, sea cucumber triterpene glycosides, esters of polyhydroxysteroids from starfish, sea urchins free sterols, and sea cucumber fucosylated chondroitin sulfates. This Special Issue, “Echinoderm Metabolites: Structure, Functions, and Biomedical Perspectives”, is a collection of articles about different scientific aspects concerning low molecular weight and biopolymer metabolites from echinoderms, including their isolation and chemical structures, biological activities, biosynthesis and evolution, biological functions, and obtaining of semi-synthetic derivatives of biologically active natural products. This Special Issue includes materials about sea urchin naphtoquinoid pigments and their semi-synthetic derivatives, sea cucumber triterpene glycosides, esters of polyhydroxysteroids from starfish, sea urchin free sterols, and sea cucumber fucosylated chondroitin sulfates

Medicinal Plants from Ancient Tradition as a Source for Matrix Proteases Inhibitors. Study of Correlation between Biological Activity and Phytochemical Profile

Considering the crucial involvement of matrix metalloproteinases’ (MMPs) misregulated activity in the pathogenesis of several degenerative diseases, this class of enzymes has been considered a highly active set of targets for the design of new therapeutic agents. However, the scant success of synthetic MMP inhibitors, largely due to the disappointing results obtained in both clinical and preclinical studies, makes medicinal plants a valuable source of new active compounds able to modulate MMPs activity. In this work, a consistent number of plants, selected on the base of an ethnobotanical research, were tested as inhibitors of collagenase, the founding member of the MMPs family. 1H-NMR-based metabolomic analysis combined with multivariate data treatment (PLS and OPLS) was used to correlate the biological activity to the phytochemical profiles, suggesting tannins as an important class of collagenase inhibitors. Thus, a tannin-removal procedure was developed, which allowed to prove this hypothesis and to identify another class of active metabolites, the glucuronide-conjugated flavonoids (especially quercetin-3-O-β-glucoronide), whose the plant Alchemilla vulgaris was found to be a good source. In another stage of the project, different varieties of tea were investigated as collagenase inhibitors, finding black tea samples particularly potent. Then, an OPLS model was developed with the aim of correlating the biological activity to the UV-Vis spectra of teas, showing that a high activity was related to absorption values in the range 350-440 nm. A subsequent fractionation of the most active tea sample was carried out, and this approach allowed to corroborate the results obtained by the metabolomic analysis. Considering that the absorbance measurement of an extract represents a cheap and simple procedure, the proposed method can be suitable, for instance, to select the best tea variety to be developed as an anti-wrinkles cosmetic or food supplement

From diversity to convergence : British computer networks and the Internet, 1970-1995

The Internet's success in the 21st century has encouraged analysts to investigate the origin of this network. Much of this literature adopts a teleological approach. Works often begin by discussing the invention of packet switching, describe the design and development of the ARPANET, and then examine how this network evolved into the Internet. Although the ARPANET was a seminal computer network, these accounts usually only briefly consider the many other diverse networks that existed. In addition, apart from momentary asides to alternative internetworking solutions, such as the Open Systems Interconnection (OSI) seven-layer reference model, this literature concentrates exclusively on the ARPANET, the Internet, and the World Wide Web. While focusing on these subjects is important and therefore justified, it can leave the reader with the impression that the world of networking started with the ARPANET and ended with the Internet. This thesis is an attempt to help correct this misconception. This thesis analyses the evolution of British computer networks and the Internet between the years 1970 and 1995. After an introduction in Chapter 1, the thesis analyses several networks. In Chapters 2 and 3, the focus is on academic networks, especially JANET and SuperJANET. Attention moves to videotex networks in Chapter 4, specifically Prestel, and in Chapter 5, the dissertation examines electronic mail networks such as Telecom Gold and Cable & Wireless Easylink. Chapter 6 considers online services, including CompuServe, American Online, and the Microsoft Network, and the thesis ends with a conclusion in Chapter 7. All of the networks discussed used protocols that were incompatible with each other which limited the utility of the networks for their users. Although it was possible that OSI or another solution could have solved this problem, the Internet's protocols achieved this objective. This thesis shows how the networks converged around TCP/IP.EThOS - Electronic Theses Online ServiceGBUnited Kingdo