Uso del preservativo en estudiantes de secundaria de Mozambique. Diferencias en razón del género y del tipo de pareja = Condom use amongst high school students in Mozambique differences by gender and kind of partners

La mayor parte de las nuevas infecciones con el VIH en el mundo se producen por transmisión sexual entre adultos jóvenes y se aprecia una mayor vulnerabilidad en las mujeres (Gregson et al., 2002). Los principales objetivos de este trabajo son: estudiar la prevalencia del uso auto informado del preservativo durante la última relación sexual en los estudiantes de secundaria de Mozambique y la intención de emplearlo en las futuras relaciones, sea con la pareja actual o con una ocasional. Los resultados muestran que: 1) el 47% de los va rones y el 62% de las mujeres no utilizaron el preservativo, 2) tanto ellos como ellas están más seguros de que lo utilizarán con una pareja ocasional que con la actual y 3) los que emplearon el preservativo en su última relación sexual tienen más intención de volver a usarlo que aquellos que no lo emplearon

The importance of relative performance feedback information: Evidence from a natural experiment using high school students

We study the effect of providing relative performance feedback information onperformance, when individuals are rewarded according to their absolute performance. Anatural experiment that took place in a high school offers an unusual opportunity to testthis effect in a real-effort setting. For one year only, students received information thatallowed them to know whether they were performing above (below) the class average aswell as the distance from this average. We exploit a rich panel data set and find that theprovision of this information led to an increase of 5% in students grades. Moreover, theeffect was significant for the whole distribution. However, once the information wasremoved, the effect disappeared. To rule out the concern that the effect may beartificially driven by teachers within the school, we verify our results using nationallevel exams (externally graded) for the same students, and the effect remains.

Dual-Regge approach to high-energy, low-mass diffraction dissociation

A dual-Regge model with a nonlinear proton Regge trajectory in the missing mass (MX2) channel, describing the experimental data on low-mass single diffraction dissociation (SDD), is constructed. Predictions for the LHC energies are given.

The Problematic Internet Entertainment Use Scale for Adolescents: Prevalence of Problem Internet Use in Spanish High School Students

Many researchers and professionals have reported nonsubstance addiction to online entertainments in adolescents. However, very few scales have been designed to assess problem Internet use in this population, in spite of their high exposure and obvious vulnerability. The aim of this study was to review the currently available scales for assessing problematic Internet use and to validate a new scale of this kind for use, specifically in this age group, the Problematic Internet Entertainment Use Scale for Adolescents. The research was carried out in Spain in a gender-balanced sample of 1131 high school students aged between 12 and 18 years. Psychometric analyses showed the scale to be unidimensional, with excellent internal consistency (Cronbach"s alpha of 0.92), good construct validity, and positive associations with alternative measures of maladaptive Internet use. This selfadministered scale can rapidly measure the presence of symptoms of behavioral addiction to online videogames and social networking sites, as well as their degree of severity. The results estimate the prevalence of this problematic behavior in Spanish adolescents to be around 5 percent.

High-resolution mass spectrometry applied to the study of metabolome modifications in various chicken tissues after amoxicillin administration

The performance of high resolution accurate mass spectrometry (HRMS) operating in full scan MS mode was investigated for the quantitative determination of amoxicillin (AMX) as well as qualitative analysis of metabolomic profiles in tissues of medicated chickens. The metabolomic approach was exploited to compile analytical information on changes in the metabolome of muscle, kidney and liver from chickens subjected to a pharmacological program with AMX. Data consisting of m/z features taken throughout the entire chromatogram were extracted and filtered to be treated by Principal Component Analysis. As a result, it was found that medicated and non-treated animals were clearly clustered in distinct groups. Besides, the multivariate analysis revealed some relevant mass features contributing to this separation. In this context, recognizing those potential markers of each chicken class was a priority research for both metabolite identification and, obviously, evaluation of food quality and health effects associated to food consumption.