406 research outputs found

    Obtención, evaluación y manipulación del semen de verraco en una unidad de producción mexicana

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    Córdova Izquierdo, A.; Pérez Gutiérrez, J.F.; Méndez Hernández, W.; Villa Mancera, A.E.; Huerta Crispín, R.: Obtención, evaluación y manipulación del semen de verraco en una unidad de producción mexicana. Rev. vet. 26: 1, 69-74, 201

    Effective Lagrangian description of the lepton flavor violating decays Z-->li lj

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    A comprehensive analysis of the lepton flavor violating (LFV) decays Z-->li lj is presented within the effective Lagrangian approach. Both the decoupling and nondecoupling scenarios are explored. The experimental constraints from li --> lj lk \bar{lk} and li -->lj gamma as well as some relationships arising from the gauge invariance of the effective Lagrangian are used to put constraints on Z-->li lj. It is found that while current experimental data impose very strong constraints on Z-->mu e, the channel Z --> tau mu (e)still may be at the reach of the planned TESLA collider.Comment: References added, final version to appear in Physical Review

    New FOCUS results on charm mixing and CP violation

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    We present a summary of recent results on CP violation and mixing in the charm quark sector based on a high statistics sample collected by photoproduction experiment FOCUS (E831 at Fermilab). We have measured the difference in lifetimes for the D0D^0 decays: D0Kπ+D^0 \to K^-\pi^+ and D0KK+D^0 \to K^-K^+. This translates into a measurement of the yCPy_{CP} mixing parameter in the \d0d0 system, under the assumptions that KK+K^-K^+ is an equal mixture of CP odd and CP even eigenstates, and CP violation is negligible in the neutral charm meson system. We verified the latter assumption by searching for a CP violating asymmetry in the Cabibbo suppressed decay modes D+KK+π+D^+ \to K^-K^+\pi^+, D0KK+D^0 \to K^-K^+ and D0ππ+D^0 \to \pi^-\pi^+. We show preliminary results on a measurement of the branching ratio Γ(D+π+(K+π))/Γ(D+π+(Kπ+))\Gamma(D^{*+}\to \pi^+ (K^+\pi^-))/\Gamma(D^{*+}\to \pi^+ (K^-\pi^+)).Comment: 9 pages, 6 figures, requires espcrc2.sty. Presented by S.Bianco at CPConf2000, September 2000, Ferrara (Italy). In this revision, fixed several stylistic flaws, add two significant references, fixed a typo in Tab.

    Supernova 2014J at M82 – II. Direct analysis of a middle-class Type Ia supernova

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    We analyze a time series of optical spectra of SN 2014J from almost two weeks prior to maximum to nearly four months after maximum. We perform our analysis using the SYNOW code, which is well suited to track the distribution of the ions with velocity in the ejecta. We show that almost all of the spectral features during the entire epoch can be identified with permitted transitions of the common ions found in normal SNe Ia in agreement with previous studies. We show that 2014J is a relatively normal SN Ia. At early times the spectral features are dominated by Si II, S II, Mg II, and Ca II. These ions persist to maximum light with the appearance of Na I and Mg I. At later times iron-group elements also appear, as expected in the stratified abundance model of the formation of normal type Ia SNe. We do not find significant spectroscopic evidence for oxygen, until 100 days after maximum light. The +100 day identification of oxygen is tentative, and would imply significant mixing of unburned or only slight processed elements down to a velocity of 6,000 km~s−1. Our results are in relatively good agreement with other analyses in the IR. We briefly compare SN 2011fe to SN 2014J and conclude that the differences could be due to different central densities at ignition or differences in the C/O ratio of the progenitors

    Hierarchical Star Formation: Stars and Stellar Clusters in the Gould Belt

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    We perform a study of the spatial and kinematical distribution of young open clusters in the solar neighborhood, discerning between bound clusters and transient stellar condensations within our sample. Then, we discriminate between Gould Belt (GB) and local Galactic disk (LGD) members, using a previous estimate of the structural parameters of both systems obtained from a sample of O-B6 Hipparcos stars. Using this classified sample we analyze the spatial structure and the kinematic behavior of the cluster system in the GB. The two star formation regions that dominate and give the GB its characteristic inclined shape show a striking difference in their content of star clusters: while Ori OB1 is richly populated by open clusters, not a single one can be found within the boundaries of Sco OB2. This is mirrored in the velocity space, translating again into an abundance of clusters in the region of the kinematic space populated by the members of Ori OB1, and a marginal number of them associated to Sco OB2. In the light of these results we study the nature of the GB with respect to the optical segment of the Orion Arm, and we propose that the different content of star clusters, the different heights over the Galactic plane and the different residual velocities of Ori OB1 and Sco OB2 can be explained in terms of their relative position to the density maximum of the Local Arm in the solar neighborhood. Although morphologically intriguing, the GB appears to be the result of our local and biased view of a larger star cluster complex in the Local Arm, that could be explained by the internal dynamics of the Galactic disk.Comment: 23 pages, including 12 figures. Accepted for publication in MNRA

    Clustering of Dietary Patterns and Lifestyles among Spanish Children in the EsNuPI Study

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    Dietary patterns (DPs) are known to be tied to lifestyle behaviors. Understanding DPs and their relationships with lifestyle factors can help to prevent children from engaging in unhealthy dietary practices. We aimed to describe DPs in Spanish children aged 1 to <10 years and to examine their associations with sociodemographic and lifestyle variables. The consumption of toddler and young children milk formulas, enriched and fortified milk within the Spanish pediatric population is increasing, and there is a lack of evidence whether the consumption of this type of milk is causing an impact on nutrient intakes and if they are helping to reach the nutrient recommendations. Within the Nutritional Study in the Spanish Pediatric Population (EsNuPI), we considered two study cohorts and three different age groups in three year-intervals in each of them. The study cohort included 740 children in a representative sample of the urban non-vegan Spanish population and 772 children in a convenience cohort of adapted milk consumers (AMS) (including follow-on formula, toddler’s milk, growing up milk, and fortified and enriched milks) who provided information about sociodemographics, lifestyle, and dietary habits; a food frequency questionnaire was used for the latter. Principal component analysis was performed to identify DPs from 18 food groups. Food groups and sociodemographic/lifestyle variables were combined through a hierarchical cluster algorithm. Three DPs predominated in every age group and study sample: a palatable energy-dense food dietary pattern, and two Mediterranean-like DPs. However, children from the AMS showed a predominant dietary pattern markedly related to the Mediterranean diet, with high consumption of cereals, fruits and vegetables, as well as milk and dairy products. The age of children and certain lifestyle factors, namely level of physical activity, parental education, and household income, correlated closely with the dietary clusters. Thus, the findings provide insight into designing lifestyle interventions that could reverse the appearance of unhealthy DPs in the Spanish child population

    Elaboración de aplicaciones interactivas para la docencia en el grado Grado de Telecomunicación

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    En este trabajo se muestran los avances realizados en el desarrollo de aplicaciones basadas en laboratorios virtuales para el estudio de la Acústica en el Grado de Telecomunicación. En particular se muestra la extensión de la aplicación VSLM accesible vía on-line y de carácter libre. Esta aplicación está implementada en lenguaje MATLAB y se basa en una interfaz gráfica sencilla que permite simular el funcionamiento de un sonómetro offline. El módulo incorporado a la aplicación permite calcular el tiempo de reverberación y una serie de parámetros relacionados con el mismo para poder caracterizar acústicamente salas y recintos. De forma paralela se muestran los avances realizados en la mejora de la aplicación implementada con anterioridad por los autores dedicada al estudio de las ondas mecánicas en barras con diferentes condiciones de contorno. La aplicación estaba implementada inicialmente en MATLAB para la parte gráfica y el interfaz, mientras que la parte de cálculo se realizó en C++. En este trabajo se muestran los resultados iniciales y la toma de contacto para la unificación de la interfaz y el código que implementa el método numérico en C++ mediante la librería Qt.En este trabajo se muestran los avances realizados en el desarrollo de aplicaciones basadas en laboratorios virtuales para el estudio de la Acústica en el Grado de Telecomunicación. En particular se muestra la extensión de la aplicación VSLM accesible vía on-line y de carácter libre. Esta aplicación está implementada en lenguaje MATLAB y se basa en una interfaz gráfica sencilla que permite simular el funcionamiento de un sonómetro offline. El módulo incorporado a la aplicación permite calcular el tiempo de reverberación y una serie de parámetros relacionados con el mismo para poder caracterizar acústicamente salas y recintos. De forma paralela se muestran los avances realizados en la mejora de la aplicación implementada con anterioridad por los autores dedicada al estudio de las ondas mecánicas en barras con diferentes condiciones de contorno. La aplicación estaba implementada inicialmente en MATLAB para la parte gráfica y el interfaz, mientras que la parte de cálculo se realizó en C++. En este trabajo se muestran los resultados iniciales y la toma de contacto para la unificación de la interfaz y el código que implementa el método numérico en C++ mediante la librería Qt.Peer ReviewedPostprint (published version

    Functional upgrading in China’s export processing sector

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    Functional upgrading occurs when a firm acquires more sophisticated functions within an existing value chain. In this paper, we analyze if there is evidence of this type of upgrading in China’s export processing regime by investigating dynamics in the relative prevalence of Import & Assembly (IA) versus Pure Assembly (PA) processing trade over the period 2000-2013. Firms in both regimes provide similar manufacturing services to foreign companies, but IA firms also conduct the sophisticated tasks of quality control, searching, financing and storing imported materials. Consistent with a trend of functional upgrading, we show that the share of IA trade in total processing trade has increased rapidly during the period 2000-2006, both overall and within product categories. Furthermore, we find that this trend has gone hand in hand with improvements in a sector’s labor productivity and unit values. Against expectations, we find that this process has slowed down notably during the period 2006-2013.status: publishe
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