Long-distance radiative corrections to the di-pion tau lepton decay

We evaluate the model-dependent piece of O(alpha) long-distance radiative corrections to tau^- \to \pi^- \pi^0\nu_{\tau} decays by using a meson dominance model. We find that these corrections to the di-pion invariant mass spectrum are smaller than in previous calculations based on chiral perturbation theory. The corresponding correction to the photon inclusive rate is tiny (-0.15%) but it can be of relevance when new measurements reach better precision.Comment: 4 pages, 2 figures. An estimate of the shift produced in the evaluation of the h.v.p. contribution to the muon anomalous magnetic moment is added. Version to appear in Phys. Rev.

Avances en la calidad de las respuestas a preguntas de probabilidad después de una actividad de aprendizaje con tecnología

En la presente comunicación, se describen y comparan las respuestas de estudiantes de secundaria (13-14 años) a tres preguntas de un cuestionario de probabilidad antes y después de haber tenido actividades de aprendizaje con apoyo de tecnología. Las preguntas analizadas se relacionan con las nociones de variable aleatoria, espacio muestral, frecuencias y distribución en sus formas más elementales. Se asume la hipótesis de que los recursos que proporciona la tecnología permiten que los estudiantes perciban que las unidades de análisis de la probabilidad son clases de experiencias y no experiencias aisladas. Con esta hipótesis se pueden explicar algunos de los avances que los estudiantes alcanzaron en las respuestas al post-test en relación con las dadas en el pre-test. Las actividades realizadas pueden proporcionar a los estudiantes referentes para los conceptos abstractos de probabilidad que estudiarán más adelante

Proximal, Microbiological and Color Evaluation and Comparison of the Meat of Llamas (Lama glama) and Alpacas (Vicugna pacos)

In this study, the meat of llama (Lama glama) and alpaca (Vicugna pacos) were examined. Data were analyzed through the analysis of variance (ANOVA) using the Centurion Statgraphics software. The bromatological characteristics of the meat were evaluated through proximal analysis. A high percentage of protein content was identified, with a higher value in the llama meat (24.025%). Regarding the ethereal extract, minimum values ​​were obtained in the alpaca meat (2.707%), indicating lean meat. The humidity was variable depending on the conditions of the conservation, and the organic matter present in the meat defined the ash content, which was not higher than 5%. In terms of the microbiological analyses, the value ​​of viable aereobic mesophiles in llama meat was 1330 cfu/g, and in alpaca meat it was 1490 cfu/g; and the values for E. coli were 0.500 cfu/g and 1,250 cfu/g, respectively. Keywords: software, Lama glama, Vicugna pacos, proximal analysis, microbiological requirements. RESUMEN La carne de Llama (Lama glama) y Alpaca (Vicugna pacos) cumple con los requisitos para ser considerada como carne; Mediante el análisis de varianza (ANOVA) utilizando el Software Statgraphics Centurion se evalúa los requisitos bromatológicos por medio del análisis proximal de las carnes en estudio, donde se identifica un alto porcentaje en el contenido de proteína, lo que conlleva a un elevado valor biológico en ambas especies, siendo más destacada, en la carne de llama con 24,025%; En cuanto a extracto etéreo  se obtiene valores mínimos en especial en la carne de alpaca con 2,707%, favoreciendo a la obtención de carne magra; En lo referente a humedad va a ser variable dependiendo de las condiciones de conservación de la misma, mientras tanto la materia orgánica presente en la carne define el contenido de cenizas, el cual no podrá ser mayor al 5%. En relación a los análisis microbiológicos los valores de Mesófilos Aereobios Viables en la carne de llama fueron 1330 ufc/g, en la carne de alpaca 1490 ufc/g, para E. Coli  de 0,500 ufc/g, y 1,250 ufc/g respectivamente encontrándose dentro de lo establecido en la Norma, y valores no permisibles por la presencia de Coliformes Totales.    Palabras clave: software, Lama glama, Vicugna pacos, análisis proximal, requerimientos microbiológicos

La promoción de salud en la comunidad

En el presente trabajo se analiza el papel que desempeñan las universidades en la transformación y el desarrollo social, con énfasis en el rol de la extensión universitaria como núcleo clave y expresión de su pertinencia, también se estudia el impacto social en la comunidad. La extensión universitaria es una de las vías en donde la Universidad demuestra su carácter de centro cultural significativo para el desarrollo. En el trabajo se valora su importancia en la sociedad, definiciones del concepto de extensión universitaria, se analizan conceptos directamente relacionados con la temática de manera determinante

Prediction equations of skinfold in children of primary school

El objetivo de este trabajo es crear ecuaciones que estimen las medidas de los pliegues cutáneos para escolares de 6 a 13 años de edad. Como resultado se obtuvieron catorce ecuaciones que estiman algunos pliegues cutáneos. Las ecuaciones se validaron con muestras aleatorias de 479 niñas y 541 niños del estado de Puebla y otras 2 muestras aleatorias del estado de Veracruz con 155 niñas y 146 niños respectivamente; las mediciones directas se realizaron con la metodología y unidades ISAK (International Society for the Advancement of Kinanthropometry)The aim of this paper is to create equations that predict the skinfold measures for school children 6 to 13 years old. Fourteen resulting equations were derived to estimate some measures of skinfold. The equations were validated with random samples of 479 girls and 541 boys in the state of Puebla and 2 other random samples of the state of Veracruz with 155 girls and 146 boys respectively; direct measurements were performed with the methodology and units ISAK (International Society for the Advancement of Kinanthropometr

Thermoelectric power of bulk black-phosphorus

The potential of bulk black-phosphorus for thermoelectric applications has been experimentally studied. The Seebeck Coefficient (S) has been measured in the temperature range from 300 K to 385 K, finding a value of S = +335 +- 10 uV/K at room temperature (indicating a naturally occurring p-type conductivity). S increases with temperature, as expected for p-type semiconductors, which can be attributed to an increase of the charge carrier density. The electrical resistance drops up to a 40 % while heating in the studied temperature range. As a consequence, the power factor at 385 K is 2.7 times higher than that at room temperature. This work demonstrates the feasibility of black-phosphorus in thermoelectric applications, such as thermal energy scavenging, which typically require devices with high performance at temperatures above room temperature.Comment: 3 figure

Gauge invariance and radiative corrections in an extra dimensional theory

The gauge structure of the four dimensional effective theory originated in a pure five dimensional Yang-Mills theory compactified on the orbifold $S^1/Z_2$, is discussed on the basis of the BRST symmetry. If gauge parameters propagate in the bulk, the excited Kaluza-Klein (KK) modes are gauge fields and the four dimensional theory is gauge invariant only if the compactification is carried out by using curvatures as fundamental objects. The four dimensional theory is governed by two types of gauge transformations, one determined by the KK zero modes of the gauge parameters and the other by the excited ones. Within this context, a gauge-fixing procedure to quantize the KK modes that is covariant under the first type of gauge transformations is shown and the ghost sector induced by the gauge-fixing functions is presented. If the gauge parameters are confined to the usual four dimensional space-time, the known result in the literature is reproduced with some minor variants, although it is emphasized that the excited KK modes are not gauge fields, but matter fields transforming under the adjoint representation of $SU_4(N)$. A calculation of the one-loop contributions of the excited KK modes of the electroweak gauge group on the off-shell WWV, with V a photon or a Z boson, is exhibited. Such contributions are free of ultraviolet divergences and well-behaved at high energies.Comment: 7 pages, conference proceedings, a new reference was added, the title has been change

Delocalization of states in two component superlattices with correlated disorder

Electron and phonon states in two different models of intentionally disordered superlattices are studied analytically as well as numerically. The localization length is calculated exactly and we found that it diverges for particular energies or frequencies, suggesting the existence of delocalized states for both electrons and phonons. Numerical calculations for the transmission coefficient support the existence of these delocalized states.Comment: RevTeX, 12 pages, 2 PS figures adde

Comparative Field Trial Effect of <em>Brucella</em> spp. Vaccines on Seroconversion in Goats and Their Possible Implications to Control Programs

The aim of this study was to determine the seroprevalence of Brucella spp. in a goat flock and the seroconversion of three groups of animals vaccinated with Rev-1 (Brucella melitensis), RB51, and RB51-SOD (Brucella abortus) to estimate the level of protection conferred on susceptible females. Seventy-two animals were used by group. Goats were older than 3 months, seronegative to brucellosis, not vaccinated previously, and kept within positive flocks. Vaccinated animals received 2 mL of product subcutaneously in the neck region. The first block was injected with Rev-1; the second received RB51, and the third group was injected with RB51-SOD. Follow-up sampling was performed at 30, 60, 90, and 365 days postvaccination. The general prevalence of brucellosis for the three groups was 1.2% (95%CI:0.5–2.7). The seroconversion rate by day 30 after vaccination was 77.7% (95%CI:61.9–88.2) for goats vaccinated with Rev-1. At 365 days post vaccination, the percentage of seropositive goats declined to 13.8% (95%CI:6.0–28.6). At day 365 after vaccination, 2.7% (95%CI:0.4–14.1) and 5.5% (95%CI:1.5–18.1) of animals vaccinated with RB51 and RB51-SOD, respectively, became positive. Results show that the seroconversion induced by Brucella abortus RB51 and RB51-SOD vaccines is lower than that by Brucella melitensis Rev-1