575 research outputs found
Distributed data management for large scale applications
No full textImprovements in data storage and network technologies, the emergence of new highresolution scientific instruments, the widespread use of the Internet and the World Wide Web and even globalisation have contributed to the emergence of new large scale dataintensive applications. These applications require new systems that allow users to store, share and process data across computing centres around the world. Worldwide distributed data management is particularly important when there is a lot of data, more than can fit in a single computer or even in a single data centre. Designing systems to cope with the demanding requirements of these applications is the focus of the present work.This thesis presents four contributions. First, it introduces a set of design principles that can be used to create distributed data management systems for data-intensive applications. Second, it describes an architecture and implementation that follows the proposed design principles, and which results in a scalable, fault tolerant and secure system. Third, it presents the system evaluation, which occurred under real operational conditions using close to one hundred computing sites and with more than 14 petabytes of data. Fourth, it proposes novel algorithms to model the behaviour of file transfers on a wide-area network.This work also presents a detailed description of the problem of managing distributed data, ranging from the collection of requirements to the identification of the uncertainty that underlies a large distributed environment. This includes a critique of existing work and the identification of practical limits to the development of transfer algorithms on a shared distributed environment. The motivation for this work has been the ATLAS Experiment for the Large Hadron Collider (LHC) at CERN, where the author was responsible for the development of the data management middleware
Integration planning - From today to start/Bachy, G. Summary of forward workshop/Orava, R. Computing - Introduction - Architecture/McCubbin, N ; Quarrie, D. Trigger and DataAcquisition - HLT and DAQ Technical Proposal /Chris Bee.
No full text
Measurement of D-star Production In Jets From Pbarp Collisions At Square-root-s = 1.8 Tev
No full textThe production rate of charged D* mesons in jets has been measured in 1.8-TeV p»p collisions at the Fermilab Tevatron with the Collider Detector at Fermilab. In a sample of approximately 32 300 jets with a mean transverse energy of 47 GeV obtained from an exposure of 21.1 nb-1, a signal corresponding to 25.0±7.5(stat)±2.0(syst) D*±K events is seen above background. This corresponds to a ratio N(D*++D*-)/ N(jet) =0.10±0.03±0.03 for D* mesons with fractional momentum z greater than 0.1. © 1990 The American Physical Society
Seedlings' growth in response to drought stress and 2,4-dichlorophenoxyacetic acid (2,4-D)
No full textThe aim of this work was to study the effect of the herbicide, 2,4-D on a mono- cot (Lolium temulentum Linn.) and a dicot (Raphanus sativus Linn.) in relation to drought stress, in order to elucidate if the combined treatments altered the survival of the plants. Herbicide effects were investigated on a number of plant developmental stages; germination, seedling growth, mature leaves and root function, and were combined with various water stress regimes.2,4-D did not alter the germination percentage in either species when applied singly or with polyethylene glycol (PEG) induce water stress. However, rate of seedling emergence and accumulation of chlorophyll, protein and proline were inhibited. Foliar application of 2,4-D at selective concentrations showed that in addition to induced growth distortion the herbicide reduced the survivial capacity of radish but enhanced that of rye grass to later drought stress. Analysis of the content of proline (a stress metabolite) in both species indicated that the accumulation of this compound was reduced in radish but enhanced in rye grass. In contrast, when 2,4-,VJ)&^Dlapplied via the roots, from water culture, the selectivity of effect was lost since proline accumulation was reduced in both species. Use of (^14)C-2,4-D showed that the herbicide remained in the roots when applied in water culture and that since a major response was seen in the roots this implied that some signalling was occuring between the two organs. From the results it would appear that the use of low doses of herbicides such as 2,4-D may be valuable in protecting certain plants from drought stress, whilst the susceptability of other plants could be increased hence making the herbicide more effective at low concentrations
- …
