Effective action of a five-dimensional domain wall

We calculate the four-dimensional low-energy effective action for the perturbations of a two-scalar domain wall model in five dimensions. Comparison of the effective action to the Nambu-Goto action reveals the presence of an additional coupling between the light scalar field and the massless translation mode (branon excitation), which can be written in terms of the curvature scalar of the induced metric. We comment on the impact of this interaction to branon physics.Comment: 24 page

Geografía de la expansión de la Leishmaniasis en el conflicto armado en Colombia (Antioquia)

La prevalencia e incidencia de enfermedades tropicales transmitidas por vectores está determinada por la presencia de condiciones ambientales propicias para el vector y la vulnerabilidad social de poblaciones que habitan sus áreas endémicas. Fenómenos sociales como la guerra y el desplazamiento de poblaciones afectadas, deterioran aún más su vulnerabilidad social e incrementan espacialmente el número de casos de población afectada por enfermedades tropicales. En el departamento de Antioquia (Colombia) los casos de Leishmaniasis aumentaron notoriamente a partir de la década de los 90 debido a las olas de desplazamiento forzado que se presentaron como consecuencia del recrudecimiento del conflicto armado en el país

On the thin-string limit of the 6d stringlike defect model

We show that in 6d models localizing gravity on stringlike defects and satisfying the dominant energy condition, the metric exterior to the string inevitably depends on the string's thickness. As a consequence, in the limit of thin string either the gravity delocalizes, or the six-dimensional Planck scale must be much larger that the four-dimensional one.Comment: 3 pages; v2: an alternative interpretation of our results, overlooked in the first version, is adde

Quasilocalized gravity without asymptotic flatness

We present a toy model of a generic five-dimensional warped geometry in which the 4D graviton is not fully localized on the brane. Studying the tensor sector of metric perturbation around this background, we find that its contribution to the effective gravitational potential is of 4D type (1/r) at the intermediate scales and that at the large scales it becomes 1/r^{1+alpha}, 0<alpha=< 1 being a function of the parameters of the model (alpha=1 corresponds to the asymptotically flat geometry). Large-distance behavior of the potential is therefore not necessarily five-dimensional. Our analysis applies also to the case of quasilocalized massless particles other than graviton.Comment: 9 pages, 1 figure; to be published in Phys. Rev.

Aspectos morales de la biogenética

No es una sorpresa para nadie la afirmación de que estamos viviendo una "revolución biológica'. En varias ocasiones y por diversas fuentes se ha señalado que algunos de los descubrimientos científicos más significativos a corto y a largo plazo se darán en las áreas de las ciencias de la vida y biomédicas. Además, algunos de los problemas sociales más importantes de este siglo y del próximo serán biológicos o tendrán componentes biológicas importantes asociados con ellos. Las nuevas circunstancias de la vida actual que proceden de estos descubrimientos están teniendo y tendrán enormes implicaciones para la ética. De un modo muy real, la "nueva biología" ha hecho volver a éticos y teólogos a la oficina de proyectos para que reconsideren las viejas concepciones de la vida y de la muerte y de lo que significa ser hombre. Estos descubrimientos pronostican cambios dramáticos en nuestro pensamiento ético y tienen graves implicaciones para la política y las tareas legislativas

La sexualidad y el ser humano integral

Sexuality is for the service of our relationships as any other aspect of our human condition. It is not an instrument for their domination and far from being a mere biological , physical or accidental phenomenon proper to men and women it is an integral part of the expression of their own self with others. When the value of the whole human being is enhanced today it contributes to the dialogue between theology and other disciplines like anthropology, philosophy, ethics, social sciences and bioethics on behalf of the systemic promotion of the individuals.La sexualidad, al igual que todos los demás aspectos de la condición humana, está al servicio de las relaciones humanas y no puede ser invocada para dominarlas. La sexualidad no es solamente un fenómeno biológico o físico accidental a los seres humanos, sino parte integrante de su autoexpresión y de su tarea de autocomunicación a los demás. Valorar hoy al ser humano de manera integral contribuye al diálogo entre la teología y disciplinas particulares como la antropología, la filosofía, la ética, las ciencias sociales, la bioética, en orden a la promoción sistémica de las personas

La bio-ética y la reflexión teológica ante los desafíos de la ciber-ética

Está investigación aborda la función mediadora de la cultura en cuanto a su formación y al agotamiento cultural de la misma, para introducirnos en lamediación de la sociedad y desde allí enfocar la realidad de la ciudad digital como manifestación de un ambiente reencarnado; habiendo reencarnado a la ciudad digital se considera la religión como mediadora hacía la búsqueda de una auténtica receptividad y la presencia real de la ENCARNACIÓN para poder afirmar que "se trata de abrirse a los lugares donde la ciudad de Dios toma forma en medio de la nueva ciudad del ser humano que es internet"

Population Diversification in a Yeast Metabolic Program Promotes Anticipation of Environmental Shifts

Delineating the strategies by which cells contend with combinatorial changing environments is crucial for understanding cellular regulatory organization. When presented with two carbon sources, microorganisms first consume the carbon substrate that supports the highest growth rate (e.g., glucose) and then switch to the secondary carbon source (e.g., galactose), a paradigm known as the Monod model. Sequential sugar utilization has been attributed to transcriptional repression of the secondary metabolic pathway, followed by activation of this pathway upon depletion of the preferred carbon source. In this work, we demonstrate that although Saccharomyces cerevisiae cells consume glucose before galactose, the galactose regulatory pathway is activated in a fraction of the cell population hours before glucose is fully consumed. This early activation reduces the time required for the population to transition between the two metabolic programs and provides a fitness advantage that might be crucial in competitive environments

Detecting bacterial endophytes in tropical grasses of the Brachiaria genus and determining their role in improving plant growth

Plant-growth-promoting (PGP) bacteria include a diverse group of soil bacteria thought to stimulate plant growth by various mechanisms. Brachiaria forage grasses, of African origin, are perennials that often grow under low-input conditions and are likely to harbour unique populations of PGP bacteria. Three bacterial strains that tested positive for nitrogenase reductase gene sequences (nifH) were isolated from Brachiaria hybrid CIAT 36062 and introduced into Brachiaria hybrid cv. Mulato, which also had indigenous endophytic bacteria testing positive for nifH gene sequences. Under conditions of nutrient deficiency, inoculated Mulato plants had significantly higher biomass production, chlorophyll and total nitrogen contents in leaves than do control plants and were darker green. Strains ofendophytic bacteria were then artificially introduced into Brachiaria  brizantha CIAT 6294, which does not have indigenous endophytic bacteria. Results were consistent with those obtained with artificially inoculated Mulato plants, suggesting that these endophytic bacteria do benefit plant growth. DNA sequence analysis demonstrated that the nifH gene sequences were highly similar to those from Klebsiella pneumoniae and other N2-fixing organisms and that the nif genes had consensus  sequences identical to those of other N2-fixing bacteria.Key words: Bacterial endophytes, green fluorescent protein, nitrogenase reductase, plant growth-promoting bacteria, Brachiaria

Determination of fetal maturity from the measurement of the sedimentary fraction of the amniotic fluid (amniocrit)

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