Exact monopole instantons and cosmological solutions in string theory from abelian dimensional reduction

We compute the exact string vacuum backgrounds corresponding to the non-compact coset theory $SU(2,1)/SU(2)$. The conformal field theory defined by the level $k= 4$ results in a five dimensional singular solution that factorizes in an asymptotic region as the linear dilaton solution and a $S^3$ model. It presents two abelian compact isometries that allow to reinterpreting it from a four dimensional point of view as a stationary and magnetically charged space-time resembling in some aspects the Kerr-Newman solution of general relativity. The $k=\frac{13}{7}$ theory on the other hand describes a cosmological solution that interpolates between a singular phase at short times and a $S^1 \times S^2$ universe after some planckian times.Comment: 18 pages, section 5 replaced by 5 and 6, references added; to appear in Phys. Rev.

Administración y planeación general de la formación profesional

El texto presenta un esquema completo de toda la metodología que se utilizaba para programar la formación profesional en el SENA, con el propósito de dar los elementos, herramientas e ideas generales y específicas que permitieran lograr con éxito la labor del Instructor.The text presents a complete outline of all the methodology that was used to program vocational training at SENA, with the purpose of giving the general and specific elements, tools and ideas that would allow the Instructor's work to be successfully achieved.Introducción -- Objetivo general -- Administración de la Formación Profesional -- Planeación general de la Formación Profesional -- Etapa de planeación -- Etapa de programación -- Etapa de evaluaciónnaDocumento sin fecha, se aproxima fecha a la década39 página

Investigaciones y estudios sobre revoques simil piedra

En los últimos años se vienen realizando tareas de reparación, reciclaje y restauración en edificios y construcciones, muchos de los cuales son importantes monumentos, siendo algunos de ellos considerados los edificios mas valiosos del patrimonio arquitectónico del país. No obstante en muchos de los casos los proyectos están por debajo de los niveles técnicos, lógicos y serios que se deberían considerar al efectuar estas intervenciones. En este trabajo se pretende aportar al desarrollo de investigaciones y técnicas de laboratorio que permitirían encarar estos emprendimientos con base científica al suplantar revoques o revestimientos originales y alterados por patologías por materiales y técnicas actuales. Se consideran las determinaciones clásicas de análisis físico, químico y petrográfico de los materiales intervinientes y se presentan algunas técnicas sencillas para relacionar la porosidad y permeabilidad de los revestimientos y su velocidad de deterioro principalmente las vinculadas con las alteraciones visuales. Además, se comentan resultados preliminares del análisis de microfotografías de revestimientos simil piedra tomadas en edificios actualmente en proceso de restauración con las formulaciones propuestas para el reemplazo. Con los datos obtenidos podemos orientar fuertemente que tipo de mortero puede ser más adecuado para sustituir revestimientos alterados por el agua en edificios históricos

Gauge invariant perturbation theory and non-critical string models of Yang-Mills theories

We carry out a gauge invariant analysis of certain perturbations of $D-2$-branes solutions of low energy string theories. We get generically a system of second order coupled differential equations, and show that only in very particular cases it is possible to reduce it to just one differential equation. Later, we apply it to a multi-parameter, generically singular family of constant dilaton solutions of non-critical string theories in $D$ dimensions, a generalization of that recently found in arXiv:0709.0471[hep-th]. According to arguments coming from the holographic gauge theory-gravity correspondence, and at least in some region of the parameters space, we obtain glue-ball spectra of Yang-Mills theories in diverse dimensions, putting special emphasis in the scalar metric perturbations not considered previously in the literature in the non critical setup. We compare our numerical results to those studied previously and to lattice results, finding qualitative and in some cases, tuning properly the parameters, quantitative agreement. These results seem to show some kind of universality of the models, as well as an irrelevance of the singular character of the solutions. We also develop the analysis for the T-dual, non trivial dilaton family of solutions, showing perfect agreement between them.Comment: A new reference added

Monopoles and Holography

We present a holographic theory in AdS_4 whose zero temperature ground state develops a crystal structure, spontaneously breaking translational symmetry. The crystal is induced by a background magnetic field, but requires no chemical potential. This lattice arises from the existence of 't Hooft-Polyakov monopole solitons in the bulk which condense to form a classical object known as a monopole wall. In the infra-red, the magnetic field is screened and there is an emergent SU(2) global symmetry.Comment: 33 pages, 16 figures; v2: ref adde

Effect of zinc intake on growth in infants: A meta-analysis

A systematic review and meta-analysis of available randomized controlled trials (RCTs) was conducted to evaluate the effect of zinc (Zn) intake on growth in infants. Out of 5500 studies identified through electronic searches and reference lists, 19 RCTs were selected after applying the exclusion/inclusion criteria. The influence of Zn intake on growth was considered in the overall meta-analysis. Other variables were also taken into account as possible effect modifiers: doses of Zn intake, intervention duration, nutritional status, and risk of bias. From each select growth study, final measures of weight, length, mid upper arm circumference (MUAC), head circumference, weight for age z-score (WAZ), length for age z-score (LAZ), and weight for length z-score (WLZ) were assessed. Pooled β and 95% confidence interval (CI) were calculated. Additionally, we carried out a sensitivity analysis. Zn intake was not associated with weight, length, MUAC, head circumference, and LAZ in the pooled analyses. However, Zn intake had a positive and statistically effect on WAZ (β = 0.06; 95%CI 0.02 to 0.10) and WLZ (β = 0.05; 95%CI 0.01 to 0.08). The dose–response relationship between Zn intake and these parameters indicated that a doubling of Zn intake increased WAZ and WLZ by approximately 4%. Substantial heterogeneity was present only in length analyses (I2 = 45%; p = 0.03). Zn intake was positively associated with length values at short time (four to 20 weeks) (β = 0.01; CI 95% 0 to 0.02) and at medium doses of Zn (4.1 to 8 mg/day) (β = 0.003; CI 95% 0 to 0.01). Nevertheless, the effect magnitude was small. Our results indicate that Zn intake increases growth parameters of infants. Nonetheless, interpretation of these results should be carefully considered

La obturación de valles por procesos de ladera: el origen de La Vega de Metztitlan (México)

[Resumen] En las estribaciones de la Sierra Madre Oriental (México) se localiza el lago de Metztitlán y la vega del mismo nombre. Su origen se debe a la obturación del valle por un importante deslizamiento y posteriormente un desprendimiento. En este trabajo se exponen los primeros resultados del estudio geomorfológico, se aporta una cartografía de detalle y se propone una primera explicación de la evolución del área.[Abstract] The lake and valley of Metztilán is located in Sierra Madre Oriental range (Mexico). Its origin is due to the slope collapse after great rockslide. This paper exposes the firsts geomorphologic analysis of the feature, and includes and detailed geomorphologic map. A different evolution phases is determined

The loss and gain of functional amino acid residues is a common mechanism causing human inherited disease

Elucidating the precise molecular events altered by disease-causing genetic variants represents a major challenge in translational bioinformatics. To this end, many studies have investigated the structural and functional impact of amino acid substitutions. Most of these studies were however limited in scope to either individual molecular functions or were concerned with functional effects (e.g. deleterious vs. neutral) without specifically considering possible molecular alterations. The recent growth of structural, molecular and genetic data presents an opportunity for more comprehensive studies to consider the structural environment of a residue of interest, to hypothesize specific molecular effects of sequence variants and to statistically associate these effects with genetic disease. In this study, we analyzed data sets of disease-causing and putatively neutral human variants mapped to protein 3D structures as part of a systematic study of the loss and gain of various types of functional attribute potentially underlying pathogenic molecular alterations. We first propose a formal model to assess probabilistically function-impacting variants. We then develop an array of structure-based functional residue predictors, evaluate their performance, and use them to quantify the impact of disease-causing amino acid substitutions on catalytic activity, metal binding, macromolecular binding, ligand binding, allosteric regulation and post-translational modifications. We show that our methodology generates actionable biological hypotheses for up to 41% of disease-causing genetic variants mapped to protein structures suggesting that it can be reliably used to guide experimental validation. Our results suggest that a significant fraction of disease-causing human variants mapping to protein structures are function-altering both in the presence and absence of stability disruption