José María Pérez

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Data replication is a practical and effective method to achieve efficient and fault-tolerant data access in grids. Traditionally, data replication schemes maintain an entire replica in each site where a file is replicated, providing a read-onlymodel. These solutions require huge storage resources to store thewhole set of replicas and do not allow efficient(More)
WaaL is a membrane enzyme implicated in ligating undecaprenyl-diphosphate (Und-PP)-linked O antigen to lipid A-core oligosaccharide. We determined the periplasmic location of a large (EL5) and small (EL4) adjacent loops in the Escherichia coli K-12 WaaL. Structural models of the EL5 from the K-12, R1 and R4 E. coli ligases were generated by molecular(More)
Functional requirements for information systems can be modeled through use cases. Furthermore, use case models have been successfully used in broader contexts than software engineering, as systems engineering. Even if small systems may be modeled as a set of use cases, when large systems requirements are modeled with a plain use case model several(More)
Parallelism in file systems is obtained by using several independent server nodes supporting one or more secondary storage devices. This approach increases the performance and scalability of the system, but a fault in one single node can stop the whole system. To avoid this problem, data must be stored using some kind of redundant technique, so any data(More)
One important piece of system software for clusters is the parallel file system. All current parallel file systems and parallel I/O libraries for clusters do not use standard servers, thus it is very difficult to use these systems in heterogeneous environments. However why use proprietary or special-purpose servers on the server end of a parallel file(More)
OBJECTIVES To compare temporal and pressure values between racewalking and normal walking (freely selected speed) and evaluate the impact of racewalking on normal walking. DESIGN AND PARTICIPANTS Temporal and plantar-pressure values were recorded (xPression system) during normal walking and racewalking in 8 high-level racewalkers. The Wilcoxon test was(More)
The current study aims at measuring mental health in a sample of Italian workers as to evaluate the usability of the 12-item General Health Questionnaire (GHQ-12), both at individual and organizational levels. Indeed, working in unhealthy organizations appears to be particularly risky for workers. A database was built from data collected through a survey of(More)