Raphael de Aquino Gomes  Fbio M. Costa 《Concurrency and Computation》2011,23(17):2092-2106

Opportunistic grid computing middleware has as a main concern the need to preserve the performance of the local applications running on machines that donate resources to the grid. This concern, together with the fact that it happens in an extremely dynamic environment, causes the adoption of a treatment based on thetextitbest‐effort principle for grid applications. This means that efficient application management schemes are usually not employed, which results in less than optimal performance as grid applications often need to be restarted due to (often temporary) resource claims by local user applications. This paper presents a method to improve the performance of grid applications, taking into account resource usage profiles for local applications, trying to identify when such resource claims are temporary and avoiding costly actions such as the migration of grid tasks. The approach is proposed as an extension to the InteGrade middleware and its evaluation shows promising results for the efficient management of grid applications. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

    

Joaquim M. Oliveira  Noriko Kotobuki  Alexandra P. Marques  Rogério P. Pirraco  Johan Benesch  Motohiro Hirose  Silgia A. Costa  João F. Mano  Hajime Ohgushi  Rui L. Reis 《Advanced functional materials》2008,18(12):1840-1853

Novel highly branched biodegradable macromolecular systems have been developed by grafting carboxymethylchitosan (CMCht) onto low generation poly(amidoamine) (PAMAM) dendrimers. Such structures organize into sphere‐like nanoparticles that are proposed to be used as carriers to deliver bioactive molecules aimed at controlling the behavior of stem cells, namely their proliferation and differentiation. The nanoparticles did not exhibit significant cytotoxicity in the range of concentrations below 1 mg mL^?1, and fluorescent probe labeled nanoparticles were found to be internalized with highly efficiency by both human osteoblast‐like cells and rat bone marrow stromal cells, under fluorescence‐activated cell sorting and fluorescence microscopy analyses. Dexamethasone (Dex) has been incorporated into CMCht/PAMAM dendrimer nanoparticles and release rates were determined by high performance liquid chromatography. Moreover, the biochemical data demonstrates that the Dex‐loaded CMCht/PAMAM dendrimer nanoparticles promote the osteogenic differentiation of rat bone marrow stromal cells, in vitro. The nanoparticles exhibit interesting physicochemical and biological properties and have great potential to be used in fundamental cell biology studies as well as in a variety of biomedical applications, including tissue engineering and regenerative medicine.  相似文献   

  总被引：1，自引：0，他引：1  

Michael Xenos  & Patricia Moy 《The Journal of communication》2007,57(4):704-718

Given the significant rise in the number of Americans who turn to the Internet for political information, we examine the effects of these behaviors on political and civic engagement in an evolving media landscape. Specifically, we test hypotheses derived from competing models—the instrumental approach, which posits direct effects of Internet use and a psychological approach, which predicts contingent effects. Analyses of the 2004 American National Election Studies ( N = 1,212) reveal a pattern of direct effects of Internet use on basic information acquisition and use but contingent effects for concrete acts of civic or political engagement. These results provide an important window on the political impacts of contemporary Internet use and suggest that future reassessments of the Internet's role in public life should continue to probe for direct as well as differential effects.  相似文献   

    

Tom Dunkley  Veronica Costa  Arno Friedlein  Sebastian Lugert  Stefan Aigner  Martin Ebeling  Meghan T. Miller  Christoph Patsch  Paolo Piraino  Paul Cutler  Ravi Jagasia 《Proteomics. Clinical applications》2015,9(7-8):684-694

  相似文献   

    

Miltiadis D. Lytras  Patricia Ordóñez de Pablos 《人机工程学与制造业中的人性因素》2008,18(4):464-479

The combined study of the literature about human resource management and the resource‐based view of the firm and organizational learning provides an analysis framework useful for understanding how strategic human resource management systems contribute to the creation and development of a sustained competitive advantage for the firm. This article has two major aims. First, it provides a conceptual framework linking simultaneously three theoretical blocks: (a) human resource management, (b) organizational learning and knowledge management, and (c) sustained competitive advantage. Second, the article builds a causal model and tests it with a sample of Spanish firms from the manufacturing industry using structural equation modeling (SEM). After the performance of a cluster analysis, a group of 72 learning firms is identified and used to test the model. Finally, major conclusions and implications for management are drawn and further avenues for research are suggested. © 2008 Wiley Periodicals, Inc.  相似文献   

    

João Paulo Costa  Pedro Cortesão Godinho  João Carlos Clímaco 《International Transactions in Operational Research》2005,12(4):455-472

This paper presents a multiobjective financial planning model and a technique for characterizing its solutions through the visual exploration of the reference point space. The financial planning model includes two objectives: (1) to maximize the company's value and (2) to stabilize the company's capital structure. The model also considers other planning issues like the balance of funds, the stabilization of dividend payout over the years and some limitations on debt. A technique of visual exploration of the reference point space is proposed in order to characterize the non‐dominated (efficient) model solutions. The underlying idea is not simply to choose a plan or a strategy, but to learn, explore and classify different decision strategies, gaining insight into them according to the preferred model of the decision makers.  相似文献   

    

Michelle F. Bowman  Patricia A. Chambers  David W. Schindler 《河流研究与利用》2007,23(8):858-876

Nutrient availability has long been considered one of the most important factors regulating production of benthic algae in oligotrophic rivers; yet, empirical relationships do not have as wide an application as similar models derived for lentic systems. The aim of this research was to derive empirical relationships between nutrient concentrations and benthic algal abundance and to identify commonalities with other studies to improve our understanding of constraints on algae in oligotrophic rivers. Surveys of physical, chemical and biological attributes of oligotrophic mountain rivers in spring, summer and autumn for 2 years confirmed that small amounts of anthropogenic phosphorus (0.1–5.6 µg/L total phosphorus (TP)) resulted in 4‐ to 30‐fold increases in abundance of benthic algae and benthic macroinvertebrates (BMIs). Algal accrual along a gradient in nutrient availability was not masked by grazing pressure but was positively correlated with abundance of scrapers. Epilithic abundance was highest downstream of anthropogenic nutrient sources in autumn. We concluded that benthic algal abundance in these mountain rivers was weakly correlated with phosphorus availability if light was not limiting but ultimately controlled by temperature and river discharge. Therefore, we recommend more direct measures of nutrient limitation be used to predict changes in ecological integrity at the lower end of the resource gradient. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

    

J. Norberto Pires  J. M. G. S da Costa 《Robotics and Computer》2000,16(1):29-42

Flexible manufacturing systems (FMS) are essential for small/medium batch and job shop manufacturing. These types of production systems are used to manufacture a considerable variety of products with medium/small production volumes. Therefore, the manufacturing platforms supporting these types of production must be flexible and organized in flexible manufacturing cells (FMC). Programming FMCs remains a difficult task and is an actual area of research and development. This paper reports an object-oriented approach developed for FMC programming. The work presented was first thought for application in industrial robot manipulators, and later extended to other FMC equipments just by putting the underlying ideas in a general framework. Initially, the motivation for this work was to develop means to add force control to a standard industrial robot manipulator. This problem requires remote access to the robot controller, remote programming and monitoring, as also is required to program and monitor any other FMC equipment. The proposed approach is distributed based on a client/server model and runs on Win32 platforms, i.e., Microsoft Windows and Windows NT. Implementation for the special case of industrial robot manipulators is presented, along with some application examples used for educational, research and industrial purposes.  相似文献   

    

Karina Barbosa de Queiroz  Roney Santos Coimbra  Amanda Rios Ferreira  Cláudia Martins Carneiro  Nívia Carolina Nogueira Paiva  Daniela Caldeira Costa  Elísio Alberto Evangelista  Renata Guerra‐Sá 《Molecular nutrition & food research》2014,58(12):2331-2341

  相似文献   

    

Patricia García‐Herrera  María Cortes Sánchez‐Mata  Montaña Cámara  Javier Tardío  Begoña Olmedilla‐Alonso 《Journal of the science of food and agriculture》2013,93(7):1692-1698

  相似文献