iCanCloud: A Flexible and Scalable Cloud Infrastructure Simulator

Simulation techniques have become a powerful tool for deciding the best starting conditions on pay-as-you-go scenarios. This is the case of public cloud infrastructures, where a given number and type of virtual machines (in short VMs) are instantiated during a specified time, being this reflected in the final budget. With this in mind, this paper introduces and validates iCanCloud, a novel simulator of cloud infrastructures with remarkable features such as flexibility, scalability, performance and usability. Furthermore, the iCanCloud simulator has been built on the following design principles: (1) it’s targeted to conduct large experiments, as opposed to others simulators from literature; (2) it provides a flexible and fully customizable global hypervisor for integrating any cloud brokering policy; (3) it reproduces the instance types provided by a given cloud infrastructure; and finally, (4) it contains a user-friendly GUI for configuring and launching simulations, that goes from a single VM to large cloud computing systems composed of thousands of machines.     

Virulence-resistance plasmids (pUO-StVR2-like) in meat isolates of Salmonella enterica serovar Typhimurium

During a screening of Salmonella enterica in foods of animal origin four isolates of serovar Typhimurium carrying hybrid virulence-resistance plasmids were detected. Three of them, one from pork and two from chicken meat, contained pUO-StVR2, a derivative of the pSLT virulence plasmid with the bla_OXA-1, catA1, aadA1, sulI and tet(B) genes, which confer resistance to ampicillin, chloramphenicol, streptomycin-spectinomycin, sulfonamides and tetracycline, respectively. The fourth isolate, from pork, harbored a pUO-StVR2 variant (termed ν8) with an additional dfrA10 gene responsible for resistance to trimethoprim. This gene is part of the orf513-dfrA10-qacEΔ1-sul1 element characteristically found in complex class 1 integrons. Pulsed-field gel electrophoresis identified two XbaI-BlnI combined profiles: X2-B2 generated from the three pUO-StVR2 isolates, and X12-B17 shown by the pUO-StVR2-ν8 isolate. The same profiles have also been found in clinical and ill pig isolates, supporting chicken and pork meat as vehicles for transmission of Typhimurium carrying pUO-StVR2-like plasmids.     

A parallel evolutionary algorithm for technical market indicators optimization

This paper deals with the optimization of parameters of technical indicators for stock market investment. Price prediction is a problem of great complexity and, usually, some technical indicators are used to predict market trends. The main difficulty in using technical indicators lies in deciding a set of parameter values. We proposed the use of Multi-Objective Evolutionary Algorithms (MOEAs) to obtain the best parameter values belonging to a collection of indicators that will help in the buying and selling of shares. The experimental results indicate that our MOEA offers a solution to the problem by obtaining results that improve those obtained through technical indicators with standard parameters. In order to reduce execution time is necessary to parallelize the executions. Parallelization results show that distributing the workload of indicators in multiple processors to improve performance is recommended. This parallelization has been performed taking advantage of the idle time in a corporate technology infrastructure. We have configured a small parallel grid using the students Labs of a Computer Science University College.     

Public Service Broadcasting's Participation in the Reconfiguration of Online News Content1

This article analyses public service broadcasting in Europe, looking at public broadcasters' role as promoters of participative processes. Computer‐mediated communication and studies rooted in mediated human interactivity are used to explore participative elements provided by digital technology, and how these can be incorporated into the news websites, through an empirical study of 5 case studies in the European market. The analysis is based on the methodology of content analysis with the goal of outlining the particularities of the participative elements implemented by each broadcaster and revealing the most common participative strategies. The findings suggest that although public service broadcasters offer a wide variety of possibilities, encouraging audiences to take on more active roles, their role is still peripheral and complementary.     

Assessment of resistance spot welding quality based on ultrasonic testing and tree-based techniques

Classification and regression tree (CART) and random forest techniques were proposed as pattern recognition tools for classification of ultrasonic oscillograms of resistance spot welding (RSW) joints. The results showed that CART models produced an acceptable error rate with high interpretability. These features may be used to understand and control the decision processes, instruct other human operators, compare margins of safety or modify them depending on the criticality of the industrial process. Compared with CART trees, random forests reduced the error rate at the cost of decreasing decision interpretability. The use of the agreement of the forest was proposed as a measure to reduce the workload of human operators, who would only have to focus on the analysis of ultrasonic oscillograms that are difficult to interpret.     

Modelling commuting time in the US: Bootstrapping techniques to avoid overfitting

The research on commuting has emerged in recent decades, but the issue of whether the empirical techniques used are appropriate has not been analysed. Thus, results from prior research could be based on non-accurate models, leading to misleading conclusions. We apply an algorithmic approach based on bootstrapping, variable selection, and mean absolute prediction errors, which is designed to avoid overfitting. Using the American Time Use Survey, we find that models with a reduced set of explanatory variables have similar accuracy to standard econometric models. Our results shed light on the importance of determining whether models can be overfitted.