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Selected AbstractsA standards-based Grid resource brokering service supporting advance reservations, coallocation, and cross-Grid interoperabilityCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 18 2009Erik Elmroth Abstract The problem of Grid-middleware interoperability is addressed by the design and analysis of a feature-rich, standards-based framework for all-to-all cross-middleware job submission. The architecture is designed with focus on generality and flexibility and builds on extensive use, internally and externally, of (proposed) Web and Grid services standards such as WSRF, JSDL, GLUE, and WS-Agreement. The external use provides the foundation for easy integration into specific middlewares, which is performed by the design of a small set of plugins for each middleware. Currently, plugins are provided for integration into Globus Toolkit 4 and NorduGrid/ARC. The internal use of standard formats facilitates customization of the job submission service by replacement of custom components for performing specific well-defined tasks. Most importantly, this enables the easy replacement of resource selection algorithms by algorithms that address the specific needs of a particular Grid environment and job submission scenario. By default, the service implements a decentralized brokering policy, striving to optimize the performance for the individual user by minimizing the response time for each job submitted. The algorithms in our implementation perform resource selection based on performance predictions, and provide support for advance reservations as well as coallocation of multiple resources for coordinated use. The performance of the system is analyzed with focus on overall service throughput (up to over 250 jobs per min) and individual job submission response time (down to under 1,s). Copyright © 2009 John Wiley & Sons, Ltd. [source] Characteristics of Emergency Medicine Program DirectorsACADEMIC EMERGENCY MEDICINE, Issue 2 2006Michael S. Beeson MD Objectives: To characterize emergency medicine (EM) program directors (PDs) and compare the data, where possible, with those from other related published studies. Methods: An online survey was e-mailed in 2002 to all EM PDs of programs that were approved by the Accreditation Council of Graduate Medical Education. The survey included questions concerning demographics, work hours, support staff, potential problems and solutions, salary and expenses, and satisfaction. Results: One hundred nine of 124 (88%) PDs (69.7% university, 27.5% community, and 2.8% military) completed the survey; 85.3% were male. Mean age was 43.6 years (95% confidence interval [CI] = 42.6 to 44.7 yr). The mean time as a PD was 5.7 years (95% CI = 4.9 to 6.5 yr), with 56% serving five years or less. The mean time expected to remain as PD is an additional 6.0 years (95% CI = 5.2 to 6.8). A 1995 study noted that 50% of EM PDs had been in the position for less than three years, and 68% anticipated continuing in their position for less than five years. On a scale of 1 to 10 (with 10 as highest), the mean satisfaction with the position of PD was 8.0 (95% CI = 7.2 to 8.3). Those PDs who stated that the previous PD had mentored them planned to stay a mean of 2.0 years longer than did those who were not mentored (95% CI of difference of means = 0.53 to 3.53). Sixty-five percent of PDs had served previously as an associate PD. Most PDs (92%) have an associate or assistant PD, with 54% reporting one; 25%, two; and 9%, three associate or assistant PDs. A 1995 study noted that 62% had an associate PD. Ninety-two percent have a program coordinator, and 35% stated that they have both a residency secretary and a program coordinator. Program directors worked a median of 195 hours per month: clinical, 75 hours; scholarly activity, 20 hours; administrative, 80 hours; and teaching and residency conferences, 20 hours; compared with a median total hours of 220 previously reported. Lack of adequate time to do the job required, career needs interfering with family needs, and lack of adequate faculty help with residency matters were identified as the most important problems (means of 3.5 [95% CI = 3.2 to 3.7], 3.4 [95% CI = 3.2 to 3.6], and 3.1 [95% CI = 2.9 to 3.3], respectively, on a scale of 1 to 5, with 5 as maximum). This study identified multiple resources that were found to be useful by >50% of PDs, including national meetings, lectures, advice from others, and self-study. Conclusions: Emergency medicine PDs generally are very satisfied with the position of PD, perhaps because of increased support and resources. Although PD turnover remains an issue, PDs intend to remain in the position for a longer period of time than noted before this study. This may reflect the overall satisfaction with the position as well as the increased resources and support now available to the PD. PDs have greater satisfaction if they have been mentored for the position. [source] Using neutral landscapes to identify patterns of aggregation across resource pointsECOGRAPHY, Issue 3 2006Jill Lancaster Many organisms are aggregated within resource patches and aggregated spatially across landscapes with multiple resources. Such patchy distributions underpin models of population regulation and species coexistence, so ecologists require methods to analyse spatially-explicit data of resource distribution and use. I describe a method for analysing maps of resources and testing hypotheses about how resource distribution influences the distribution of organisms, where resource patches can be described as points in a landscape and the number of organisms on each resource point is known. Using a mark correlation function and the linearised form of Ripley's K-function, this version of marked point pattern analysis can characterise and test hypotheses about the spatial distribution of organisms (marks) on resource patches (points). The method extends a version of point pattern analysis that has wide ecological applicability, it can describe patterns over a range of scales, and can detect mixed patterns. Statistically, Monte Carlo permutations are used to estimate the difference between the observed and expected values of the mark correlation function. Hypothesis testing employs a flexible neutral landscape approach in which spatial characteristics of point patterns are preserved to some extent, and marks are randomised across points. I describe the steps required to identify the appropriate neutral landscape and apply the analysis. Simulated data sets illustrate how the choice of neutral landscape can influence ecological interpretations, and how this spatially-explicit method and traditional dispersion indices can yield different interpretations. Interpretations may be general or context-sensitive, depending on information available about the underlying point pattern and the neutral landscape. An empirical example of caterpillars exploiting food plants illustrates how this technique might be used to test hypotheses about adult oviposition and larval dispersal. This approach can increase the value of survey data, by making it possible to quantify the distribution of resource points in the landscape and the pattern of resource use by species. [source] From Good Student to Outcast: The Emergence of a Classroom IdentityETHOS, Issue 2 2004Stanton Wortham The process of social identification draws on heterogeneous resources from several levels of explanation. This article illustrates how, by describing the identity development of one student across an academic year in a ninth-grade classroom. Analyses of transcribed classroom conversations show teachers and students drawing on multiple resources as this student goes from being identified as one of many good students to being identified as a disruptive outcast. This case provides a counterexample to simple theories of identity development that do not recognize the multiple, heterogeneous resources involved in social identification. [source] Distribution and growth of benthic macroinvertebrates among different patch types of the littoral zones of two arctic lakesFRESHWATER BIOLOGY, Issue 12 2006STEVEN R. BEATY Summary 1. To evaluate the effect of habitat patch heterogeneity on abundance and growth of macroinvertebrates in arctic lakes, macroinvertebrate abundance, individual biomass, and potential food resources were studied in three patch types in two arctic lakes on the Alaskan North Slope near the Toolik Lake Field Station. An experiment was conducted to determine which sediment patch type supported higher growth rates for Chironomus sp., a commonly occurring macroinvertebrate. 2. Potential organic matter (OM) resources were significantly higher in both rock and macrophyte patches than in open-mud patches. Total macroinvertebrate densities in both lakes were highest in rock patches, intermediate in macrophytes and lowest in open-mud. The open-mud patches also had lower species richness compared with other patch types. Additionally, individual biomass for one clam species and two chironomid species was significantly greater in rock patches than in open-mud. 3. In a laboratory experiment, Chironomus showed two to three times greater mass increase in sediments from macrophyte and rock patches than from open-mud patches. Rock and macrophyte experimental sediments had at least 1.5 × the percentage OM as open-mud sediments. 4. Chlorophyll a appeared to be the best predictor for invertebrate abundances across all patch types measured, whereas OM content appeared to be the variable most closely associated with Chironomus growth. 5. Our results combined with previous studies show that the relationships between macroinvertebrate community structure, individual growth, and habitat heterogeneity are complex, reflecting the interaction of multiple resources, and biotic interactions, such as the presence or absence of a selective vertebrate predator (lake trout, Salvelinus namaycush). [source] Will agri-environment schemes deliver substantial biodiversity gain, and if not why not?JOURNAL OF APPLIED ECOLOGY, Issue 1 2007MARK J. WHITTINGHAM Summary 1One of the main aims of agri-environment schemes (AES) is to increase biodiversity on farmland. Common conservation practice is to identify areas containing valuable resources (e.g. habitats, ecosystems and species) and then to protect them: ,protected area' schemes. AES differ from typical protected area schemes because they are often applied to small patches of land, such as field boundaries, and are sometimes located in areas where the target species does not occur. 2AES require an enormous amount of funding and they have been applied across a large geographical area, i.e. the European Union. However, recent evidence suggests mixed results regarding the effects of AES on biodiversity. 3It is hard to predict the consequences of AES on biodiversity because a number of factors are seldom accounted for explicitly. For example: (i) the occurrence of target species will vary between patches; (ii) there will be variation in habitat preference by species in different geographical areas; (iii) both optimal foraging theory and metapopulation theory predict that the distance from breeding individuals is likely to determine patch use; (iv) if resources are widely spread then the home ranges of some species may need to increase to encompass the multiple resources needed for breeding. The potential for these factors to affect the outcome of AES on biodiversity is discussed. 4Synthesis and applications. AES are likely to increase biodiversity if a lower number of larger resource patches are provided, in contrast to current practice that promotes many small fragmented areas of environmental resource. One way of achieving this may be to run these schemes more like traditional protected area schemes, with farms or groups of farms managed using extensive farming methods. Such an approach negates some of the problems of current AES and may help to address a wider range of concerns held by different countryside stakeholders. [source] Retaining knowledge for document management: Category-tree integration by exploiting category relationships and hierarchical structuresJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2010Christopher C. Yang The category-tree document-classification structure is widely used by enterprises and information providers to organize, archive, and access documents for effective knowledge management. However, category trees from various sources use different hierarchical structures, which usually make mappings between categories in different category trees difficult. In this work, we propose a category-tree integration technique. We develop a method to learn the relationships between any two categories and develop operations such as mapping, splitting, and insertion for this integration. According to the parent-child relationship of the integrating categories, the developed decision rules use integration operations to integrate categories from the source category tree with those from the master category tree. A unified category tree can accumulate knowledge from multiple resources without forfeiting the knowledge in individual category trees. Experiments have been conducted to measure the performance of the integration operations and the accuracy of the integrated category trees. The proposed category-tree integration technique achieves greater than 80% integration accuracy, and the insert operation is the most frequently utilized, followed by map and split. The insert operation achieves 77% of F1 while the map and split operations achieves 86% and 29% of F1, respectively. [source] Seedling growth and morphology of three oak species along field resource gradients and seed mass variation: a seedling age-dependent responseJOURNAL OF VEGETATION SCIENCE, Issue 3 2010Ignacio M. Pérez-Ramos Abstract Question: What is the relative importance of seed mass and abiotic factors in species-specific seedling growth and morphology during the first and the second growing season? How do oak species respond along gradients of these factors? Location: Mediterranean oak forest in southern Spain. Methods: We analysed seedling growth components and morphology of three co-occurring Quercus species (two deciduous and one evergreen). Oak seeds with a wide variety of sizes were sown along broad gradients of abiotic conditions. Intra- and inter-specific differences were evaluated by calibrating maximum likelihood estimators of seedling growth during the first two years of life. Results: We found multiple resources and conditions affecting seedling morphology and biomass allocation. However, the integrative variables of seedling growth , total aboveground biomass and relative growth rate (RGR) , were affected by two main factors: seed mass and light conditions. The relative contribution of these two factors depended strongly on seedling age. Seed mass explained most of the growth and morphological variables during the first year, while light conditions were the best predictor in the second growing season. In contrast, soil factors did not play an important role in seedling growth. We found some evidence of regeneration niche partitioning between oak species along the light gradient, a reflection of their distribution patterns as adults at the study site. Conclusions: We conclude that inter-specific differences in seedling growth, arising from seed size variability and microsite heterogeneity, could be of paramount importance in oak species niche segregation, driving stand dynamics and composition along environmental gradients. [source] | |||||||||||||