Presentación de una escala para evaluar actitudes y creencias sobre la sexualidad reproductiva en adolescentes varones de la región Caribe colombiana / Presentation of an Attitudes and Beliefs Scale to Assess Adolescent Sexuality and Reproductive Health of Young Males in the Caribbean Region

Este artículo presenta la construcción y comprobación de la confiabilidad de un instrumento para evaluar las actitudes y normas subjetivas en el comportamiento sexual y reproductivo en varones en dos estudios. La escala fue administrada a 965 estudiantes varones escolarizados, entre 11 a 19 años de edad, en la región Caribe colombiana. En el Estudio 1 (pilotaje) el cuestionario constituido por 150 ítems se redujo a 78 en la prueba final. En la escala de actitud protección (Media = 4.1 y DE = 1.07) se obtuvo un alfa de Cronbach de 0.93 y en la de actitud abstinencia/retardo (Media = 3.6 y DE = 1.26), un alfa de 0.88 y homogeneidad elevada con correlación ítem-total superiores a 0.6. Para la escala de creencias categorizada como normas subjetivas (Media = 3.79 y DE = 1.08) la estimación del alfa de Cronbach fue de 0.98 y homogeneidad adecuada con correlaciones superiores a 0.66. La evaluación de la validez de constructo mediante el análisis factorial exploratorio y análisis de componentes principales con rotación VARIMAX, denota adecuación satisfactoria de los datos a la matriz factorial en el Estudio 2 (escala definitiva). En conclusión el instrumento es confiable, de estructura estable para la medición de actitudes y normas subjetivas en sexualidad reproductiva y contribuirá a establecer acciones específicas en programas, acorde a las expectativas en salud sexual y reproductiva de los adolescentes varones.

This paper presents the construction and testing of the reliability of an instrument to assess attitudes and subjective norms sexual and reproductive behavior of young males. The scale was administered to 965 male students (From of 11 to 19 years) enrolled at school in the Colombian Caribbean region. This work includes two independent studies, in the Study 1 (pilot) the questionnaire consisted of 150 items and it was reduced to 78. In the protective attitude scale (Mean = 4.1 and SD = 1.07) was obtained Cronbach's alpha of 0.93 and for the abstinence / delay attitude (Mean = 3.6 and SD = 1.26) an alpha of 0.88 with high homogeneity. The total correlation item was greater than 0.6 for all the attitude scales. On the scale of beliefs represented by the subjective norms (Mean = 3.79 and SD = 1.08) the estimation of Cronbach's alpha was 0.98 with correlations above 0.66. In Study 2 (final stop), the construct validity assessment using factorial analysis and principal components analysis with VARIMAX rotation reported a satisfactory fit of the data to the array factor. In conclusion, the instrument has a reliable and stable structure for the measurement of attitudes and subjective norms for sexuality and reproductive health, and it is useful to help in the setting of programs.

Stretching single atom contacts at multiple subatomic step-length.

This work describes jump-to-contact STM-break junction experiments leading to novel statistical distribution of last-step length associated with conductance of a single atom contact. Last-step length histograms are observed with up to five for Fe and three for Cu peaks at integral multiples close to 0.075 nm, a subatomic distance. A model is proposed in terms of gliding from a fcc hollow-site to a hcp hollow-site of adjacent atomic planes at 1/3 regular layer spacing along with tip stretching to account for the multiple subatomic step-length behavior.

A Straightforward Approach for the Determination of the Maximum Time Step for the Simulation of Nanometric Metallic Systems.

In the present work, we report on a systematic analysis to determine the maximum time step allowed in molecular dynamics simulations applied to study metal systems of current interest in nanoscience. Using the velocity Verlet integration scheme, we have found that it is possible to use a 20 fs time step for the simulation of gold nanosystems. This is roughly an order of magnitude greater than the usually employed integration step (2 to 5 fs). We also propose a general criterion to select this maximum time step for other metallic nanosystems, even in the case of bimetallic nanosystems.