Thermodynamic analysis of unimer-micelle and sphere-to-rod micellar transitions of aqueous solutions of sodium dodecylbenzenesulfonate

Temperature dependence of specific conductivity of sodium dodecylbenzenesulfonate (NaDBS) aqueous solutions was analyzed. Two breaks on the plot appeared for all temperature, which suggest two micellar transitions. This has been corroborated by surface tension measurements. The first transition concentration occurs at the critical micelle concentration (CMC), whilst the second critical concentration (so-called transition micellar concentration, TMC) is due to a sphere-to-rod micelles transition. The dependence of CMC and TMC on the temperature allows the computation of the corresponding thermodynamic functions: Gibbs free energy, enthalpy and entropy changes. For the CMC, enthalpy and entropy increments were found that decrease with the temperature values. However, an anomalous behavior was obtained for the TMC, where both ΔS0 and ΔH0 values raised with the temperature increase. However, for both transitions, an (enthalpy + entropy) compensation is observed. These results will be compared with similar systems reported in the literature

Anthropometric measures as predictive indicators of metabolic risk in a population of “holy week costaleros”

Preventive measures are a priority in those groups that perform intense physical efforts without physical preparation and that can also be overweight or obese. One of the groups that reflect these characteristics is the costaleros of the Holy Week of Andalusia, Spain. This paper aims to describe the effect of obesity on blood pressure. A descriptive cross-sectional study was conducted on 101 costaleros. The anthropometric measures were determined through segmental impedance. Cardiac recovery and anaerobic power were measured through the Ruffier–Dickson test and the Abalakov test, respectively. Blood pressure was measured when the individuals were at rest. The Kruskal–Wallis test was applied for of continuous parameters and the X2 test for dichotomous measures. Binary logistic regression models were used for the subsequent analysis with R-square and Receiver Operating Characteristic (ROC) curves. The average population was 28 years of age, 173.7 cm tall, and 82.59 Kg weigh. The excess of body fat was 11.27 Kg and Body Mass Index was 27.33 Kg/m2. 72.3% showed abnormal blood pressure and 68.2% were overweight. 32.7% had a waist-hip ratio higher than 0.94. The probability of presenting abnormal blood pressure was higher among the subjects whose fat content was higher and muscle content was lower

Effect of being the organizer of a Handball Worl Championship in team perfomance

Cuando un equipo actúa como local parece tener cierta ventaja. Este hecho se denomina home advantage (HA) y ha sido muy estudiado en competiciones de liga, pero poco en competiciones de sede única. Se analizaron 4.340 partidos disputados en todos los Campeonatos del Mundo de balonmano disputados hasta 2011. Las variables registradas fueron: partidos ganados, empatados, perdidos, número goles marcados y recibidos y sexo de los competidores. La HA en los Campeonatos del Mundo de balonmano es de 67,9±0,23 para la categoría masculina y de 71,2±0,27 para la femenina. Existe una asociación entre la HA, los puntos obtenidos y la clasificación final del equipo.When a team plays at home seems to get some advantage. This effect is called home advantage (HA) and has been widely studied in league competitions, but little in competitions in a single venue. 4.340 games played in all Handballl World Championships since 1936 to 2011 were analyzed. The variables registered were games won, games drawn, games lost, the number of goals scored and goals against and the gender of the competitors. The HA (mean±sd) in the World Handball Championships is 67.9±0.23, for the male category and 71.2±0.27 for the female. A significant association exists between HA, the points obtained in a competition and the final classification of a team

Rational exploitation of a granite outcrop

[Abstract] This piece analizes the possibilities of mining exploitation in a little outcrop of rOSfl granite. The zone has been researched, recognizing the main structural discontinuities, and characterizing the rock mass by the geomechanic classificationofBARTON. Two core drilling have been made to study the evolution ofthe deeper bed. The volume ofthe bed has been calculated by geometric calculation in the researched area. The theories ofCASTAING and RABU have been developed to estimate the useful volume of the bed for a minimum block size of 1 m3. We have implerríented a computer program in base ofEXCEL 4.0. The result is a useful volume of 51.67 %. By the application of the reduction coefficients ofsterility and irregularity, the maximum estimated efficiency of the exploitation is 33 %

Exterior Differential System for Cosmological G2 Perfect Fluids and Geodesic Completeness

In this paper a new formalism based on exterior differential systems is derived for perfect-fluid spacetimes endowed with an abelian orthogonally transitive G2 group of motions acting on spacelike surfaces. This formulation allows simplifications of Einstein equations and it can be applied for different purposes. As an example a singularity-free metric is rederived in this framework. A sufficient condition for a diagonal metric to be geodesically complete is also provided.Comment: 27 pages, 0 figures, LaTeX2e, to be published in Classical and Quantum Gravit

Non-singular radiation cosmological models

In this paper we analyse the possibility of constructing singularity-free inhomogeneous cosmological models with a pure radiation field as matter content. It is shown that the conditions for regularity are very easy to implement and therefore there is a huge number of such spacetimes.Comment: 13 pages, LaTex, ws-mpla, to appear in Modern Physics Letters

Optimización del proceso kraft en maderas de Eucalyptus globulus

Se ha estudiado en maderas de E. globulus como afecta el factor H y la carga de álcali activo en cocción sobre la facilidad de la deslignificación, el contenido en carbohidratos y la eliminación de extractos de las pastas crudas obtenidas a un mismo nivel de lignina residual. Los resultados obtenidos mostraron que trabajar con bajas cargas de álcali activo y temperaturas en cocción más elevadas, aumenta el rendimiento de pasta en cocción y eliminan más sitosterol. Sin embargo, las blancuras más altas se obtienen trabajando con alta carga de álcali activo. Los xilanos son los compuestos más sensibles a la alta carga de álcali y se eliminan en gran extensión. Las pastas obtenidas con bajo álcali residual en cocción tienen mejor estallido y tracción pero peor drenabilidad, volumen, opacidad y porosidad.___________________________________This paper studies how H factor and active alkali loads in cooking affect E. globulus woods with regard to ease of delignification, carbohydrate content or removal of extractives. The results obtained demonstrated that working with low alkali loads and higher cooking temperatures increase pulp production and remove greater amounts of sitosterol. However, the greatest brightness is achieved by working with a high active alkali load. Xylans are the most sensitive compounds to high alkali loads and to a large extent are removed. Pulp produced with low residual alkali in the cooking stage has better burst index and tensile strength, but lower dewatering, bulk, opacity and air permeability

Current methods of soccer match analysis

Ha sido realizada una revisión de 86 artículos, con el objetivo de analizar a través de los estudios más recientes los beneficios y limitaciones de los nuevos sistemas para el análisis del futbolista durante el partido, debido a que las mayores exigencias en el rendimiento del fútbol moderno está obligando a replantearse cuáles son sus demandas físicas, así como los modelos de planificación y los métodos de entrenamiento tradicionales. Los resultados muestran que el vídeo análisis asistido por ordenador para la codificación de los patrones de movimiento y la tecnología GPS se presentan como herramientas de gran utilidad para conocer mejor la carga física del jugador, mientras que el diseño observacional facilita la evaluación del comportamiento técnico-táctico del futbolista y el equipo. Como conclusión podemos decir que hemos observado sin embargo una metodología diferente entre las opciones comerciales disponibles y una tecnología ubicada todavía en una etapa inicial de desarrolloA review of 86 references has been made, in order to analyze through the most recent studies the benefits and limitations of the new systems for the analysis of soccer player during the match, due to the fact that the greater performance requirements of modern soccer is forcing to review his physical demands, as well as planning models and traditional training methods. The results show that the computer-aided video analysis for coding movement patterns and the GPS technology are presented as very useful tools for a better understanding of the players physical load, whereas the observational design facilitates assessment of the technical-tactical behavior of the soccer player and the team. In conclusion we can say that we have however observed a different methodology among the available commercial options and a technology still placed at an initial stage of development

Estructura condicional en los preseleccionados gallegos de diferentes categorías de formación en balonmano

[Resumen] Los objetivos generales del presente estudio son describir la estructura condicional de lso jugadores preseleccionados gallegos en balonmano, desde la categoría infantil hasta la júnior, para situar a nuestra población con otras poblaciones de deportistas en las edades estudiadas. También, analizar las características condicionales de los seleccionados y no seleccionados de cada categoría, para determianr las variables que discriminan entre ambos grupos, para elaborar modelos de predicción del rendimiento deportivo basados en las variables correspondientes a los diferentes indicadores estudiados. Para la consecución de estos objetivos estudiamos a 125 varones jóvnes, que viven y desarrollan su actividad deportiva en Galicia, de edades comprendidas entre 13 y 21 años, por tanto pertenecientes a las categorías infantiles, cadetes, juveniles y júnior. La selección de los sujetos fue realizada por el conjunto de entrenadores de Galicia (juicio de expertos). Para caracterizar la población se realización cuatro valoraciones: de los antecedentes deportivos (VAD), cineantropométrica (VC), de la condición física (VCF) y multidimensional (VM). Los instrumentos de medida fueron, respectivamente, un cuestionario, los protocolos recomendados por el grupo español de cineantropometría, la batería Eurofil y pruebas de salto vertical y, finalmente, un análisis estadístico multivariante denominado análisis discriminante en la VM, y aplicado al conjunto de las tres valoraciones anteriores en función de la variable dependiente dicotómica seleccionado/no seleccionado (SEL/NO SEL). El estudio tiene un carácter descriptivo y transversal, y tomó como punto de partido el diseño elaborado por Solamellas y Rodríguez en 1995. Constatamos que muestra población se inició más tarde y dedican menos sesiones y horas de entrenamiento semanales que otros deportistas