Gravity lens critical test for gravity constants and dark sector

The recent study of the strong gravitational lens ESO 325-G004 [1] leads to a new possibility for testing General Relativity and its extensions. Such gravity lens observational studies can be instrumental for establishing a limitation on the precision of testing General Relativity in the weak-field regime and on the two gravity constants (the Newtonian and cosmological ones) as described in [2]. Namely, we predict a critical value for the involved weak-field parameter \gamma_{cr}=0.998 (for M= 1.5 10^{11} M_{\odot} lens mass and r=2 kpc light impact distance), which remarkably does not depend on any hypothetical variable but is determined only by well measured quantities. If the critical parameter \gamma_{cr} will be established at future observations, this will mark the first discrepancy with General Relativity of conventional weak-field Newtonian limit, directly linked to the nature of dark sector of the Universe.Comment: To appear in Eur Phys J C; 3 pages; minor revisio

Two fundamental constants of gravity unifying the dark matter and the dark energy

The common nature of the dark sector - dark energy and dark matter - as shown in [1] follows readily from the consideration of generalized Newtonian potential as a weak-field General Relativity. That generalized potential satisfying the Newton's theorem on the equivalence of sphere's gravity and that of a point-mass located in its center, contains an additional constant which along with the gravitational constant is able to explain quantitatively both the dark energy (cosmological constant) and dark matter. So, gravity is defined not by one but two fundamental constants. We show that, the second constant is dimensional-independent and matter-uncoupled and hence is even more universal than the gravitational constant, thus affecting the strategy of observational studies of dark energy and of the search of dark matter.Comment: To appear in Eur Phys J C; 5 page

The cosmological constant derived via galaxy groups and clusters

The common nature of dark matter and dark energy is argued in [1] based on the approach that the cosmological constant \Lambda enters the weak-field General Relativity following from Newton theorem on the "sphere-point mass" equivalency [2]. Here we probe the \Lambda-gravity description of dark matter in galaxy systems, from pairs up to galaxy clusters using the data of various sources, i.e. of Local Supercluster galaxy surveys, gravity lensing and Planck satellite. The prediction that the cosmological constant has to be the lower limit for the weak-field \Lambda obtained from galaxy systems of various degree of virialization is shown to be supported by those observations. The results therefore support the \Lambda-gravity nature of dark matter in the studied systems, implying that the positivity of the cosmological constant might be deduced decades ago from the dynamics of galaxies and galaxy clusters far before the cosmological SN surveys.Comment: To appear in Eur Phys J C, 7 page

Síntomas, niveles de estrés y estrategias de afrontamiento en una muestra de estudiantes masculinos y femeninos de una institución de educación superior militar: análisis comparativo

Trabajo de investigaciónEl objetivo de la investigación fue identificar y comparar los síntomas y niveles de estrés característicos de la población estudiantil femenina y masculina en una institución de educación superior militar de Bogotá D.C., y las estrategias de afrontamiento adoptadas por dicha población tanto en su formación militar como académica. El estudio que se llevó a cabo es de tipo cuantitativo, descriptivo, correlacional y comparativo. Los participantes fueron 261 estudiantes que estuvieron matriculados en dicha institución, 43 mujeres y 218 hombres con edades comprendidas entre los 18 y los 24 años, que fueron dados de alta para adelantar sus estudios superiores en esta institución, con condiciones adecuadas, tanto de salud física como psicológica, y que no presentaban ningún tipo de antecedente judicial o administrativo. Como instrumentos se utilizaron: el Cuestionario para la evaluación del estrés, tercera versión (Villalobos, 2010) y la Escala de estilos y estrategias de afrontamiento (Londoño, Pérez, & Murillo, 2009). El análisis comparativo se llevó a cabo utilizando la “t de Student”, y el análisis correlacional, por medio de la “r de Pearson”; adicionalmente se utilizó la “h de Tukey” para refinar el análisis. Los resultados de la aplicación demuestran que no hay diferencias estadísticamente significativas entre los dos sexos en las variables estudiadas y que tanto los niveles de estrés como las estrategias de afrontamiento a este son similares para ambos sexos en todas las carreras y semestres.RESUMEN ABSTRACT ANTECEDENTES TEÓRICOS Y EMPÍRICOS JUSTIFICACIÓN Y PLANTEAMIENTO DEL PROBLEMA. OBJETIVOS VARIABLES MÉTODO HIPÓTESIS CONSIDERACIONES ÉTICAS RESULTADOS DISCUSIÓN CONCLUSIONES Y RECOMENDACIONESMaestríaMagister en Psicologí

An example of the stochastic dynamics of a causal set

An example of a discrete pregeometry on a microscopic scale is introduced. The model is a directed dyadic acyclic graph. This is the particular case of a causal set. The particles in this model must be self-organized repetitive structures. The dynamics of this model is a stochastic sequential growth dynamics. New vertexes are added one by one. The probability of this addition depends on the structure of existed graph. The particular case of the dynamics is considered. The numerical simulation provides some symptoms of self-organization.Comment: 7 pages, 5 figures, work presented at the conference "Foundations of Probability and Physics-6" (FPP6) held on 12-15 June 2011 at the Linnaeus University, V\"axj\"o, Swede

Vitamin A Transport Mechanism of the Multitransmembrane Cell-Surface Receptor STRA6.

Vitamin A has biological functions as diverse as sensing light for vision, regulating stem cell differentiation, maintaining epithelial integrity, promoting immune competency, regulating learning and memory, and acting as a key developmental morphogen. Vitamin A derivatives have also been used in treating human diseases. If vitamin A is considered a drug that everyone needs to take to survive, evolution has come up with a natural drug delivery system that combines sustained release with precise and controlled delivery to the cells or tissues that depend on it. This "drug delivery system" is mediated by plasma retinol binding protein (RBP), the principle and specific vitamin A carrier protein in the blood, and STRA6, the cell-surface receptor for RBP that mediates cellular vitamin A uptake. The mechanism by which the RBP receptor absorbs vitamin A from the blood is distinct from other known cellular uptake mechanisms. This review summarizes recent progress in elucidating the fundamental molecular mechanism mediated by the RBP receptor and multiple newly discovered catalytic activities of this receptor, and compares this transport system with retinoid transport independent of RBP/STRA6. How to target this new type of transmembrane receptor using small molecules in treating diseases is also discussed