Introducción a la simulación de modelos de colas

La teoría de colas es una rama de la teoría de la probabilidad en la que se estudian modelos matemáticos de colas reales con el objetivo de optimizar o mejorar ciertos aspectos de ellas. Las colas surgen cuando la demanda de un servicio supera la oferta disponible. Uno de los ejemplos más sencillos de colas es el de personas esperando en fila en la caja de un supermercado, pero la teoría de colas también se aplica en ámbitos tan dispares como el tráfico aeroportuario, la asignación de operaciones informáticas o la atención sanitaria. En el apartado teórico se explican los conceptos básicos referentes a procesos estocásticos y teoría de colas. Además, se desarrollan con más detalle los modelo de colas Markovianos M/M/1, M/M/c y M/M/c/k. Por otro lado, también se exponen las nociones esenciales relativas a simulaciones, generación de variables aleatorias y replicaciones. Por último, en el tercer capítulo realizamos una serie de simulaciones con el lenguaje R. Simulamos un mismo sistema M/M/2/3 con los paquetes simmer, queueing y queuecomputer y analizamos los resultados comparándolos con los esperados según el desarrollo teórico. Finalmente, concluimos el trabajo simulando un sistema más complejo con el paquete simmer y estudiando los resultados.Queueing theory is a branch of probability theory in which mathematical models of real queues are studied with the aim of optimising or improving certain aspects of them. Queues exist when the demand for a service exceeds the available supply. One of the simplest examples of queues is that of people waiting in line at a supermarket checkout, but queuing theory is also applied in areas as diverse as airport traffic, the allocation of computer operations or health care. The theoretical section explains the basic concepts of stochastic processes and queuing theory.In addition, the Markovian queuing models M/M/1, M/M/c and M/M/c/k are developed in more detail. On the other hand, the essential notions on simulations, generation of random variables and replications are also presented. Finally, in the third chapter we carry out a series of simulations with the R language. We simulate the same M/M/2/3 system with the simmer, queueing and queuecomputer packages and analyse the results in comparison with those expected according to the theoretical development. Finally, we conclude the work by simulating a more complex system with the simmer package and studying the results.Universidad de Sevilla. Doble Grado en Matemáticas y Estadístic

Machine-Learning based analysis and classification of Android malware signatures

Multi-scanner Antivirus (AV) systems are often used for detecting Android malware since the same piece of software can be checked against multiple different AV engines. However, in many cases the same software application is flagged as malware by few AV engines, and often the signatures provided contradict each other, showing a clear lack of consensus between different AV engines. This work analyzes more than 80 thousand Android applications flagged as malware by at least one AV engine, with a total of almost 260 thousand malware signatures. In the analysis, we identify 41 different malware families, we study their relationships and the relationships between the AV engines involved in such detections, showing that most malware cases belong to either Adware abuse or really dangerous Harmful applications, but some others are unspecified (or Unknown). With the help of Machine Learning and Graph Community Algorithms, we can further combine the different AV detections to classify such Unknown apps into either Adware or Harmful risks, reaching F1-score above 0.84.The authors would like to acknowledge the support of the national project TEXEO (TEC2016-80339-R), funded by the Ministerio de Economia y Competitividad of SPAIN through, and the EU-funded H2020 SMOOTH project, Spain (grant no. H2020-786741). Similarly, the authors would like to remark the support provided by the Tacyt system (https://www.elevenpaths.com/es/te cnologia/tacyt/index.html) for the collection and labeling of AV information. Finally, Ignacio Martin would like to acknowledge the support granted by the Spanish Ministry of education through the FPU scholarship he holds (FPU15/03518)

Llano Alto (Béjar-Salamanca) : aula activa de la naturaleza

Copia digital : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Stable genetic diversity despite parasite and pathogen spread in honey bee colonies

In the last decades, the rapid spread of diseases, such as varroosis and nosemosis, associated with massive honey bee colonies mortality around the world has significantly decreased the number and size of honey bee populations and possibly their genetic diversity. Here, we compare the genetic diversity of Iberian honey bee colonies in two samplings performed in 2006 and 2010 in relation to the presence of the pathogenic agents Nosema apis, Nosema ceranae, and Varroa destructor in order to determine whether parasite and pathogen spread in honey bee colonies reflects changes in genetic diversity. We found that the genetic diversity remained similar, while the incidence of N. ceranae increased and the incidence of N. apis and V. destructor decreased slightly. These results indicate that the genetic diversity was not affected by the presence of these pathogenic agents in the analyzed period. However, the two groups of colonies with and without Nosema/Varroa detected showed significant genetic differentiation (G test). A detailed analysis of the allelic segregation of microsatellite loci in Nosema/Varroa-negative colonies and parasitized ones revealed two outlier loci related to genes involved in immune response.We thank beekeepers for providing the samples analyzed. This study was supported by INIA-FEDER grant numbers RTA2013-00042-C10-05 and 06 and RTA2008-00020-C02. The corresponding author of this paper is presently a member and receive support from COST Action FA1307 (Sustainable pollination in Europe: joint research on bees and other pollinators (SUPER-B). Irene Muñoz is supported by Fundación Séneca (Murcia, Spain) through the post-doctoral fellowship 19149/PD/13-N. We very much appreciated the helpful comments to improve the manuscript of two anonymous reviewers and the Editor Sven Thatje.info:eu-repo/semantics/publishedVersio

The Effect of Lifestyle Intervention on Health-Related Quality of Life in Adults with Metabolic Syndrome: A Meta-Analysis

[EN] The aim of this meta-analysis was to assess the effects of a lifestyle intervention through health education on nutrition, physical activity, and healthy habits on physical and mental health-related quality of life (HRQoL), in adults with metabolic syndrome (MetS). The databases used were PubMed, WOS, and Scopus. The inclusion criteria were: observational, longitudinal and randomized clinical trial (RCT) study designs, adults (both sexes), with at least two criteria of MetS, lifestyle intervention and comparison with a control group, and a measurement of HRQoL with a validated questionnaire. We analyzed the Hedges’ g and SF-36 score. I2 statistics were calculated and possible publication and small study biases were assessed using Egger’s test and funnel plots. Seven RCTs were selected for meta-analysis, based on 637 study participants. Significant improvements were found in the physical dimensions of the HRQoL scores for subjects in the active intervention compared to the group that received general lifestyle information (Hedges’ g 0.61, 95% confidence interval (CI) = 0.31–0.91). Mental health-related quality of life was also significantly improved in the intervention group compared with the control group (Hedges’ g 0.84, 95% CI = 0.64–1.03). In conclusion, our results suggest that, according to the RCTs selected for this meta-analysis, a lifestyle intervention significantly improves HRQoL in all its domains.SIThis research was funded by Fondo de Investigación para la Salud (FIS), which is co-funded by the European Regional Development Fund grant PI17/00532

Aceptación empresarial de las tecnologías de la información y de la comunicación: un análisis del sector servicios

The aim of this paper is to analyse the level of development reached by some Information and Communication Technologies (ICT) such as web pages, e-mail, EDI, and business management software in the business world. To this end, we have concentrated on the business behaviour of the service sector. Nevertheless, the technological development demanded changes depending on the activity of the firm, so the mediator effect of the industry has been tested in the process of innovation acceptance. Our results show the technology acceptance process is influenced by the perception of both the usefulness and the ease of use of innovations. Moreover, the industry effect mediates the technological behaviour of a firm; meanwhile, if a firm performs a "traditional activity", there are fewer incentives to implement the innovation

Mechanical response of industrial concrete with SFRC and PFRC

Concrete is one of the most commonly used construction materials in the world due to its versatility. There are different types of concrete according to the required mechanical responses, and these will depend on the composition of the elements. Therefore, additional elements have been developed to improve the properties and conditions of concrete. One of these elements is reinforcing fibers made of steel, polypropylene, glass, and so on, which, according to the base material, geometry, and dosage, improve the mechanical and workability properties and decrease and/or prevent the generation of cracks, which are some of the most common problems in industrial slabs. This study performs an analysis of the changes in the mechanical properties of concrete (compressive strength, rupture modulus, modulus of elasticity, Poisson’s ratio, and residual stress) due to the addition of fiber-reinforced concrete (FRC) to determine the physical and mechanical conditions of the fibers that improve the concrete and its application in industrial concrete. Due to the large number of samples and variables, advanced statistical methods (analysis of variance and comparative index) were used in the numerical study, which allowed to analyze and compare several results at the same time. This research is divided into two stages. In the first stage, six steel fibers (with a dosage of 2.7, 6, and 11 and three of 28¿kg/m3) and five polypropylene fibers (with a dosage of 0.6, 2.15, and 2.7 and two of 3¿kg/m3) were used in the study, and compression and bending tests (ASTM C39 and C78, respectively) were performed on 35 cylinders and 45 beams. Improvements were identified in several fiber-reinforced concrete samples in terms of compressive strength: 67% of the steel fiber samples and 100% of the polypropylene fiber samples had values above the average value of the simple concrete; in terms of the modulus of rupture, 83% of the steel fiber samples and 80% of the polypropylene fiber samples had values above the average value of the simple concrete. In the second stage, one type of steel fiber and one type of polypropylene fiber were selected for a second mechanical analysis (64 cylinders, 72 beams, and 15 slabs) with dosages of 20, 30, and 40¿kg/m3 and 2.13, 4.25, and 6.38¿kg/m3, respectively. In the second stage, statistical analysis and modeling with nonlinear analysis were used to evaluate the results, where residual strength improved but Poisson’s ratio decreased when the dosage of fibers was increased.Peer ReviewedPostprint (published version