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111.
Large-scale applications can be expressed as a set of tasks with data dependencies between them, also known as application
workflows. Due to the scale and data processing requirements of these applications, they require Grid computing and storage
resources. So far, the focus has been on developing easy to use interfaces for composing these workflows and finding an optimal
mapping of tasks in the workflow to the Grid resources in order to minimize the completion time of the application. After
this mapping is done, a workflow execution engine is required to run the workflow over the mapped resources. In this paper,
we show that the performance of the workflow execution engine in executing the workflow can also be a critical factor in determining
the workflow completion time. Using Condor as the workflow execution engine, we examine the various factors that affect the
completion time of a fine granularity astronomy workflow. We show that changing the system parameters that influence these
factors and restructuring the workflow can drastically reduce the completion time of this class of workflows. We also examine
the effect on the optimizations developed for the astronomy application on a coarser granularity biology application. We were
able to reduce the completion time of the Montage and the Tomography application workflows by 90% and 50%, respectively. 相似文献
112.
Healthcare organizations are often organized in a modular, loosely coupled fashion where separate and semi-autonomous work
units specialize in different areas of care delivery. This partitioning allows each unit to adapt to emerging practice standards
in its area of expertise and to adjust to its local work environment. However, organizational loose coupling can limit the
flow of information within organizations and can make it difficult to coordinate services when patients’ care is dependent
on professionals from more than one unit. Groupware systems have the potential to improve coordination and information access
in healthcare organizations. However, modularity and loose coupling make it difficult to introduce new systems when they span
more than one unit, since authority is not always centralized and since perceptions and frames of reference on new deployments
differ across units. In this paper, we define a groupware deployment framework for loosely coupled healthcare organizations
that has two parts: a set of deployment challenges and a set of deployment strategies. The deployment challenges include:
difficulties centralizing deployments, perceptions of inequity, role conflicts, and problems achieving critical mass. The
deployment strategies outline a preliminary set of approaches for addressing the difficulties of deploying CSCW systems in
loosely coupled healthcare organizations. We illustrate the framework by presenting a case study of a groupware deployment
in a home care setting. 相似文献
113.
Acyl-CoA cholesterol acyltransferase (ACAT) (EC 2,3,1.26) in the yolk sac membrane of chicken eggs plays an important role
in the transport of lipids, which serve as both structural components and as an energy source during embryogenesis. ACAT from
the yolk sac membrane of chicken eggs 16 d after fertilization has higher activity and better stability than its mammalian
liver counterpart. During our study of the avian enzyme, ACAI was found to be activated up to twofold during storage at 4°C.
The activation was investigated, and data suggest that redistribution of cholesterol within microsomal vesicles leads to the
increase. Methyl-β-cyclodextrin (MβCD) increases activation an additional twofold, possibly by facilitating the movement of
cholesterol within microsomal fragments and allowing redistribution of cholesterol in lipid bilayers to a greater extent.
Treatment of microsomes with MβCD removes cholesterol from the membranes. Controlled amounts of cholesterol can be restored
to the membranes by mixing them with cholesterol-phosphatidylcholine liposomes in the presence of MβCD. Under these conditions,
the plot of ACAT vs. cholesterol mole fraction in the liposomes is sigmoidal. The finding that MβCD can enhance cholesterol
transfer between liposomes and microsomes and reduce the limitation of slow movement et nonpolar molecules in aqueous media
should make cyclodextrins more useful in in vitro studies of apolar molecule transport between membrane vesicles. 相似文献
114.
This study tested whether 4-month-old infants respond primarily to objects' physical or retinal image sizes. In the study's main experiment, infants were habituated to either a 6-cm-diameter disk at a distance of 18 cm or a 10-cm disk at 50 cm. They were then given 2 test trials in which the 6- and 10-cm disks were presented side by side at a distance of 30 cm. For each infant, one test object had a novel physical size but a familiar retinal image size, and the other had a familiar physical size but a novel retinal image size. The infants exhibited a significant looking preference for the object that had a novel physical size. A preliminary experiment found that 4-month-olds' looking preferences are based on novelty, not familiarity, under the conditions of this study. Given this finding, the results suggest that 4-month-old infants attend and respond primarily to physical size, not to retinal image size. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
115.
116.
Cache memories reduce memory latency and traffic in computing systems. Most existing caches are implemented as board-based systems. Advancing VLSI technology will soon permit significant caches to be integrated on chip with the processors they support. In designing on-chip caches, the constraints of VLSI become significant. The primary constraints are economic limitations on circuit area and off-chip communications. The paper explores the design of on-chip instruction-only caches in terms of these constraints. The primary contribution of this work is the development of a unified economic model of on-chip instruction-only cache design which integrates the points of view of the cache designer and of the floorplan architect. With suitable data, this model permits the rational allocation of constrained resources to the achievement of a desired cache performance. Specific conclusions are that random line replacement is superior to LRU replacement, due to an increased flexibility in VLSI floorplan design; that variable set associativity can be an effective tool in regulating a chip's floorplan; and that sectoring permits area efficient caches while avoiding high transfer widths. Results are reported on economic functionality, from chip area and transfer width to miss ratio. These results, or the underlying analysis, can be used by microprocessor architects to make intelligent decisions regarding appropriate cache organizations and resource allocations. 相似文献
117.
Rule groups with preconditions,posteonditions,and termination conditions were added tothe ADVISE Meta-Expert System.Multiple,varying goals are also an attribute of the new rulegroups.By treating the data collection process as separating from the rule inference engine,techniques for enhanced data acquisition were developed using semantic networks to describerelations among variables and to restructure value sets for variables dynamically.Having thusextended the ADVISE tools,an automated key to alfalfa field pest identification was selected as atest application and found to be particularly well suited by the new features.A need fordisjunctive(“OR”)constructs in the right hand side of rules is discussed,and directions forfuture applications are given. 相似文献
118.
Confirmatory factor analysis was applied to the conflict and ambiguity scales developed by J. R. Rizzo et al (see record 1971-01407-001). Alternative models were contrasted to evaluate the possibilities that (a) the 14 items comprising the scales do measure the two purported constructs, (b) the 14 items measure only one construct, or (c) the 14 items load complexly on a second-order factor model. The second-order factor model was superior across three independent subject samples (total n?=?913), indicating that these measures do not establish role conflict and role ambiguity as two factorially independent constructs. The authors conclude that alternative scales are needed; suggestions for scale development are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
119.
120.