A vision of uses and gratifications applied to the study of Internet use by adolescents

Based on uses and gratifications theory, the aim of this paper is to identify the reasons for using Internet among teenagers and to check different variables in order to predict types of uses. After conducting a representative survey applied to 397 high school students in Community of Madrid (Spain), Internet users’ gratifications and their relationships with variables related to adolescent characteristics, family context and time of online exposure are analyzed. The article concludes that daily use of Internet predicts higher consumption of communication and social relationship

Enhancement of a High Speed De-Excitation System for Brushless Synchronous Machines by large blocking voltage semiconductors

One of the main disadvantage of the synchronous machines with brushless excitation is that the field winding is not accessible for the de-excitation. The de-excitation process is very slow as the field current flows through the rotating diodes which operate in freewheel mode. Therefore in case of an internal fault, despite the correct operation of the protection relays, the machine could have severe damages. A high-speed de-excitation system for these machines was developed. The de-excitation is achieved by inserting a resistance in the field circuit by a static switch semiconductor based, obtaining a dynamic response similar to that achieved in machines with static excitation. This paper presents the improvement in the de-excitation system in the second commercial 20 MVA hydro generator in operation. In this case, high blocking voltage semiconductor was used, making the dynamic response even better, than in the first hydro generator

New echinocandin susceptibility patterns for nosocomial Candida albicans in Bogotá, Colombia, in ten tertiary care centres: An observational study

Background: Candida albicans remains as the first cause of nosocomial fungal infections in hospitals worldwide and its susceptibility pattern should be better described in our tertiary care hospitals. Methods: This study aimed at identifying the caspofungin susceptibility pattern regarding nosocomial Candida albicans infection in ten tertiary care hospitals using the methodology proposed by CLSI M27-A3 and CLSI M27-S4, and its association with risk factors and clinical outcome. The approach involved descriptive research concerning the diagnosis of nosocomial infection during a 7-month period in 10 hospitals in Bogotá, Colombia. Associations were established using exact non-parametric statistical tests having a high statistical power (>95%), suitable for small samples. The exact Mann Whitney test or Kruskall-Wallis non-parametric ANOVA tests were used for distributions which were different to normal or ordinal variables when comparing three or more groups. Multivariate analysis involved using binomial, multinomial and ordinal exact logistical regression models (hierarchical) and discrimination power was evaluated using area under the ROC curve. Results: 101 nosocomial infections were found in 82,967 discharges, for a Candida spp. infection rate of 12.2 per 10,000 discharges, 30.7% caused by C. albicans, 22.8% by C. tropicalis, 20.8% by C. parapsilosis, 19.8% by other Candida, 3% by C. krusei and 3% by C. glabrata. Statistically significant associations between mortality rate and the absence of parenteral nutrition were found in multivariate analysis (OR = 39.746: 1.794-880.593 95% CI: p = 0.020). The model's predictive power was 83.9%, having an 85.9% significant prediction area (69.5%-100 95% CI; p = 0.001). Conclusions: Significant differences were found regarding susceptibility results when comparing CLSI M27-A3 to CLSI M27-S4 when shifting clinical break-point values. However, one nosocomial strain was consistent in having reduced susceptibility when using both guidelines without having been directly exposed to echinocandins beforehand and no mutations were found in the FKS1 gene for hot spot 1 and/or hot spot 2 regions, thereby highlighting selective pressure regarding widespread antifungal use in tertiary healthcare centres. Nutritional conditions and low family income were seen to have a negative effect on survival rates. © 2015 Rodríguez-Leguizamón et al.; licensee BioMed Central

Durabilidad del Concreto en Ambiente Urbanos y Urnbano/Marinos de México y España

Trabajo presentado en el III Congreso Nacional ALCONPAT (Asociación Latinoamericana de Control de Calidad, Patología y Recuperación de la Construcción), celebrado en Caracas (Venezuela), en noviembre de 200

Perfil microbiológico y sensibilidad a antibióticos de microorganismos aislados de infecciones conjuntivales en el Instituto de Oftalmología Fundación Conde de Valenciana. Reporte del año 2012

ResumenIntroducciónLa conjuntiva es el tejido ocular que se infecta con mayor frecuencia. Los agentes patógenos más frecuentes de la conjuntivitis suelen ser los virus y las bacterias. El uso indiscriminado de antibióticos de amplio espectro para tratar la conjuntivitis ha generado microorganismos resistentes.ObjetivoIdentificar los microorganismos más frecuentes aislados de muestras de origen conjuntival y conocer su susceptibilidad antibiótica.Material y métodosRevisión retrospectiva de cultivos provenientes de raspados conjuntivales obtenidos durante el 2012.ResultadosSe obtuvieron 44 muestras de origen conjuntival. Estas provinieron de 21 varones y 23 mujeres. La mediana (25%, 75%) de la edad fue 62 años (39-68). El cultivo fue positivo en 13 de las muestras obtenidas, identificándose 5 microorganismos diferentes. Staphylococcus epidermidis fue el microorganismo aislado con mayor frecuencia (9 cepas). Todas las cepas de S. epidermidis fueron sensibles a vancomicina, gentamicina, cefotaxima, moxifloxacino y ofloxacino. La mayoría de las cepas de S. epidermidis (6/9) mostraron resistencia a múltiples antibióticos.ConclusionesStaphylococcus epidermidis fue el microorganismo aislado con mayor frecuencia en muestras provenientes de infecciones conjuntivales. Todas las cepas de S. epidermidis fueron sensibles a vancomicina, gentamicina y moxifloxacino y la mayoría de ellas fueron multirresistentes a los antibióticos en evaluación.AbstractIntroductionThe conjunctiva is the tissue of the eye that gets infected with more frequency. The most common pathogens of conjunctivitis are viruses and bacteria. The indiscriminate use of broad-spectrum antibiotics to treat conjunctivitis generated resistant microorganisms.ObjectiveIdentify the most common microorganisms isolated from samples of conjunctival origin and know their antibiotic susceptibility.Material and methodsRetrospective review of culture from conjunctival swabs obtained during 2012.ResultsWe collected 44 samples of conjunctival origin. They came from 21 males and 23 women. The median (25%, 75%) of age was 62 years (39-68). The culture was positive in 13 samples, identifying five different microorganisms. Staphylococcus epidermidis was the most common isolated microorganism (9 strains). All strains of S. epidermidis were sensitive to vancomycin, gentamicin, cefotaxime, ofloxacin and moxifloxacin. The multiple antibiotic resistance was identified in the majority of strains of S. epidermidis (6/9).ConclusionsStaphylococcus epidermidis was the most common isolated microorganism from samples of conjuntival infections. All strains of S. epidermidis were sensitive to vancomycin and moxifloxacin and most of them showed multidrug resistance to antibiotics

Electrochemical Impedance Spectroscopy Behavior of Nanometric Al-Cr and Cr-Al Coatings by Magnetron Sputtering

Multilayer and bilayers structures have attracted much attention as a way of improving the mechanical and corrosion resistance properties of protective coatings. In this work the application of nanometric Al/Cr and Cr/Al bilayers deposited on AA2024-T3, AA60601-T6 aluminum alloys and AISI 9840 steel by magnetron sputtering and DC sputtering was studied. The materials were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) in order to consider their application as high corrosion resistance coatings. The corrosion behavior of the films was studied using a NaCl aqueous solution (3.5 wt %

Políticas públicas, autonomía y participación docente en contextos de transformación y cambio

Son muy escasos los organismos internacionales que se preocupan por la situación de los docentes: en América Latina la Red Estrado es uno de los contados colectivos que realiza estudios, investigaciones y propuestas por mejorar la condición humana y profesional de los educadores. En el Ecuador, en sus pocos años de funcionamiento, la Red Estrado ha tenido una presencia muy poco activa para denunciar los problemas y dificultades que afectan a los docentes, dar a conocer las fortalezas y cualidades de quienes educan a los ecuatorianos del presente y del futuro y proponer acciones concretas que aseguren el desarrollo de los integrantes del magisterio. Esta organización de la sociedad civil está integrada por un selecto grupo de académicos pertenecientes a varias universidades, quienes con una actitud totalmente desinteresada y altruista, con el apoyo de sus respectivos centros de educación superior, han organizado algunos eventos nacionales, han publicado varios libros sobre la situación docente y, de manera excepcional, han colocado este tema en el imaginario nacional, a fin de dar a conocer los aspectos relacionados con la formación inicial, el ejercicio de la carrera, las condiciones de salud y trabajo, la formación permanente, los problemas salariales, la evaluación y los demás asuntos que se relacionan con la trayectoria profesional de los educadores. El libro políticas públicas, autonomía y participación docente en contextos de transformación y cambio, que se pone a consideración de los lectores, contiene varios estudios e investigaciones llevados a cabo en estos años por algunos docentes de centros educativos ecuatorianos y otros países de América Latina

Cyclic potentiodynamic polarization on titanium alloys anodizing in alkaline solutions

Titanium alloys are used in different industries such as biomedical, aerospace, aeronautic, chemical, and naval. Those industries have high requirements with few damage tolerances. The aim of this work was to study the corrosion behavior of titanium alloys anodizing and non-anodizing in alkaline (KOH and NaOH) solutions, exposed in 3.5%wt. NaCl and 3.5% wt. H2SO4 solutions at room temperature using cyclic potentiodynamic polarization (CPP) according to standards in order to obtain electrochemical parameters as the passivation range (PR), corrosion type, passive layer persistence, corrosion potential (Ecorr), and corrosion rate. The alloy Ti Beta-C anodized presented better corrosion resistance than Ti-6Al-4V in both media. The smallest corrosion rate is presented in Beta-C samples (4.72 E-8 A/cm2) and the highest corrosion rate is CP2 (1.61 E-5 A/cm2