A free boundary model for oxygen diffusion in a spherical medium

The goal of this article is to find a correct approximated solution using a polynomial of sixth degree for the free boundary problem corresponding to the diffusion of oxygen in a spherical medium with simultaneous absorption at a constant rate, and to show some mistakes in previously published solutions.Comment: 10 pages, 6 figures and 2 tables. Paper accepted, in press in Journal of Biological Systems (2015

Reflexiones sobre la enseñanza de la física universitaria

In spite of the scientific and technological development and a worldwide increment in the number of university students, it is evident a decrease in the number of students of physics in this level. This work brings out some features of the university education, particularly the teaching of the firsts courses. At the same time it is stated that a poor didactic knowledge, a rutinary teaching, that is not participative from the part of the teachers can be linked to a growing loss of interest from the part of the students. Finally the authors give some trends to make a deep study of this problem

Book Review

Latina Teachers: Creating Careers and Guarding CultureGlenda M. FloresNew York University PressPages: 240Published: 2017Price: $29.00 (Paperback) Citation: Flores, G. M. (2017). Latina teachers: Creating careers and guarding culture. New York University Pres

An extremely high velocity molecular jet surrounded by an ionized cavity in the protostellar source Serpens SMM1

We report ALMA observations of a one-sided, high-velocity ($\sim$80 km s$^{-1}$) CO($J = 2 \rightarrow 1$) jet powered by the intermediate-mass protostellar source Serpens SMM1-a. The highly collimated molecular jet is flanked at the base by a wide-angle cavity; the walls of the cavity can be seen in both 4 cm free-free emission detected by the VLA and 1.3 mm thermal dust emission detected by ALMA. This is the first time that ionization of an outflow cavity has been directly detected via free-free emission in a very young, embedded Class 0 protostellar source that is still powering a molecular jet. The cavity walls are ionized either by UV photons escaping from the accreting protostellar source, or by the precessing molecular jet impacting the walls. These observations suggest that ionized outflow cavities may be common in Class 0 protostellar sources, shedding further light on the radiation, outflow, and jet environments in the youngest, most embedded forming stars.Comment: 6 pages, 4 figures, accepted for publication in the Astrophysical Journal Letter

Quality model for software development pymes located in the valle de Aburrá metropolitan area

Modelo de calidad para pymes desarrolladoras de software ubicadas en el área metropolitana del valle de AburráMediante este artículo se desea mostrar el proyecto de investigación (Modelo de Calidad para PYMES Desarrolladoras de Software ubicadas en el Área Metropolitana del Valle de Aburra) se presenta un Modelo de Calidad que busca servir de apoyo a las Pymes desarrolladoras de software del Área Metropolitana del Valle de Aburra. Para su creación se realizó un análisis de modelos importantes como: MoProSoft, TST/PSP, Mosca, CMI, CMMI, de los cuales se toman como base las mejores prácticas. De igual manera se analiza conceptos importantes como Modelos de Calidad, Gestión de Procesos, Metodologías de Desarrollo, Gestión de proyectos. Este modelo de calidad busca servir de base a las pequeñas empresas, creando apoyo a los equipos desarrolladores de software mejorando su rendimiento y efectividad en la elaboración de los proyectos.AbstractThe purpose of this article is to showcase a research project (Quality Model for Software Development Pymes Located in the Aburrá Valley Metropolitan Area), and to present the resulting Quality Model, intended to support PYMES that develop software and are located in the Aburrá Valley Metropolitan Area. Many important models were analyzed for its development, such as MoProSoft, TST/PSP, Mosca, CMI, CMMI, from which the best practices were extracted. Additionally, important concepts were taken into account, such as Quality Models, Process Management, Development Processes, and Project Management. This quality model aims serve as a basis for small companies by supporting their software development teams, improving their performance and effectiveness in project elaboration.Keywords: Software, Software Development Process, Quality Models, Software Qualit

Assessment of the microbiological quality of groundwater in three regions of the Valencian community (Spain)

Urban groundwater development was traditionally constrained by concerns about its quality. This study was conducted in the regions of La Ribera Alta and Ribera Baja and La Plana de Requena-Utiel of the Valencian Community (Valencia, Spain) where population density, demand for drinking water and agricultural activities are high. Groundwater bodies (GWBs) are regarded as management areas within each territory, and were used to establish protection policies. This study analyzed eleven GWBs. We used two databases with microbiological measurements from 154 wells over a 7-year period (2004-2011), risk factors and groundwater information. Wells were grouped according to frequency of microbiological contamination using E. coli measurements, category <1, or wells with low-frequency microbiological contamination and high-frequency wells or category 1-100, according to World Health Organization (WHO) quality criteria of drinking water. Of all wells, 18.12% showed high-frequency microbiological contamination with a majority distribution in the Ribera Alta region (26.98%, p < 0.001). No significant differences were found between the two risk categories for flow, static level, well depth and distance from population centres. This paper reveals that the vulnerability classes established by the Geological and Mining Institute of Spain (IGME) do not match the microbiological results, and that only eight wells with high-frequency contamination coincide with the high vulnerability areas