4,342 research outputs found

    Science with the World Space Observatory - Ultraviolet

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    The World Space Observatory-Ultraviolet (WSO-UV) will provide access to the UV range during the next decade. The instrumentation on board will allow to carry out high resolution imaging, high sensitivity imaging, high resolution (R~55000) spectroscopy and low resolution (R~2500) long slit spectroscopy. In this contribution, we briefly outline some of the key science issues that WSO-UV will address during its lifetime. Among them, of special interest are: the study of galaxy formation and the intergalactic medium; the astronomical engines; the Milky Way formation and evol ution, and the formation of the Solar System and the atmospheres of extrasolar p lanets.Comment: Just one text file (aigomezdecastro.tex). To be published in the proceeding of the conference: "New Quest in Stellar Astrophysics II: UV properties of evolved stellar populations" held in Puerto Vallarta - Mexico, in april 200

    Infinite-time concentration in aggregation-diffusion equations with a given potential

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    Typically, aggregation-diffusion is modeled by parabolic equations that combine linear or nonlinear diffusion with a Fokker-Planck convection term. Under very general suitable assumptions, we prove that radial solutions of the evolution process converge asymptotically in time towards a stationary state representing the balance between the two effects. Our parabolic system is the gradient how of an energy functional, and in fact we show that the stationary states are minimizers of a relaxed energy. Here, we study radial solutions of an aggregation-diffusion model that combines nonlinear fast diffusion with a convection term driven by the gradient of a potential, both in balls and the whole space. We show that, depending on the exponent of fast diffusion and the potential, the steady state is given by the sum of an explicit integrable function, plus a Dirac delta at the origin containing the rest of the mass of the initial datum. Furthermore, it is a global minimizer of the relaxed energy. This splitting phenomenon is an uncommon example of blow-up in inffinite time.Depto. de Análisis Matemático y Matemática AplicadaFac. de Ciencias MatemáticasFALSEUnión Europea. Horizonte 2020Ministerio de Ciencia e Innovación (MICINN)pu

    Partial mass concentration for fast-diffusions with non-local aggregation terms

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    We study well-posedness and long-time behaviour of aggregation-diffusion equations of the form ρt=Δρm+(ρ(V+Wρ))\frac{\partial \rho}{\partial t} = \Delta \rho^m + \nabla \cdot( \rho (\nabla V + \nabla W \ast \rho)) in the fast-diffusion range, 0<m<10<m<1, and VV and WW regular enough. We develop a well-posedness theory, first in the ball and then in Rd\mathbb R^d, and characterise the long-time asymptotics in the space W1,1W^{-1,1} for radial initial data. In the radial setting and for the mass equation, viscosity solutions are used to prove partial mass concentration asymptotically as tt \to \infty, i.e. the limit as tt \to \infty is of the form αδ0+ρ^dx\alpha \delta_0 + \widehat \rho \, dx with α0\alpha \geq 0 and ρ^L1\widehat \rho \in L^1. Finally, we give instances of W0W \ne 0 showing that partial mass concentration does happen in infinite time, i.e. α>0\alpha > 0

    Reproductive traits of the Colorada Pampeana goat

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    Information on seven different flocks of the Colorada goat breed in La Pampa (Argentina) was recorded during three consecutive years (1995-1997) to estimate reproductive performance. On the average, reproductive indexes were: fecundity: 87.85 percent, fertility: 92.12 percent, actual prolificity: 1.897 and commercial prolificity: 1.752. There were no signifficant differences among years for any index. On the contrary, flocks differed for fecundity and fertility percentage. Buck percentage was on the average 1.71 percent, and duration of the mating period was about 5 months. Abortus percentage was on the average 4.45 percent, being significantly higher (12.31 percent) in the dryest year. In conclusion, reproductive performance of the Colorada Pampeana goat was high, and it may be showing the adaptation of this breed to the agronomic and environmental conditions of La Pampa province.Durante tres años consecutivos (1995 a 1997) se estudiaron 7 majadas de cabra Colorada en la provincia de La Pampa (Argentina), obteniendo como promedio los siguientes índices reproductivos: fecundidad: 87,85 p.100; fertilidad: 92,12 p.100; prolificidad real: 1,897 y prolificidad comercial: 1,752. No se detectaron diferencias significativas entre años; pero sí entre establecimientos, para los índices de fecundidad y fertilidad. El porcentaje de machos reproductores utilizados para el servicio fue del 1,71 p.100, y la duración del período reproductivo fue aproximadamente de 5 meses. El porcentaje de abortos ha sido en promedio para los 3 años del 4,45 p.100, pero fue sensiblemente superior (12,31 p.100) durante el año de mayor sequía. Los altos índices reproductivos registrados confirman la buena adaptación de la cabra Colorada al medio ambiente en el que se desempeña

    Morphologic and phaneroptic characterization of the pampean red goat

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    The morphoestructure and coat characteristics of Red Goats or Wool Goats has been deteminated and compared with the remainder goats of the zone. The Red Goats were characterized as middlesized animals with 64.2 ± 2.80 cm of height at withers in females and 73.2 ± 3.61cm in males, and a live weight of 44.4 ± 6.03 kg and 71.1 ± 8.94 kg in females and males respectively. They have a strong sexual dimorphism, with a predominantly straight, head profile medium to large ear size, and Aegagrus or arch-spiral horn type. Their mantle is uniform, with an open face of fine, silky, and curli hair. Predominant mantle colours are reddish and light brown. The remainder evaluated goats have greater variability, specially in those characters important for racial diagnosis, as the front-nasal profile, horn type, ear type, pigmentation and hair characteristics.Se determinaron las características fanerópticas y medidas e índices morfológicos de cabras regionales pampeanas, particularmente del tipo que se conoce en la zona como cabra Colorada o de Lana, y se compararon con las del resto de cabras de la zona. Las cabras Coloradas son animales mediolíneos y eumétricos, de 64,2± 2,80 de alzada a la cruz en hembras y 73,2 ± 3,61cm en machos y 44,4 ± 6,03 kg y 71,1 ± 8,94 kg de peso en hembras y machos respectivamente. Son animales de fuerte dimorfismo sexual, con perfil fronto nasal predominantemente recto, orejas medianas a grandes y cuernos de tipo Aegagrus o arcoespiral. El manto es de tipo uniforme, con un vellón de pelo largo, fino, suave, sedoso y rizado, predominando las capas de color rojizo y los tostados. El resto de cabras evaluadas presentan mayor variabilidad, especialmente en aquellos caracteres de importancia en la diagnosis racial como el perfil fronto-nasal, tipo de cuernos, tipo de orejas, pigmentación y características del pelo

    Sociology of caprine production systems in western Pampa

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    Goat ranches in the west area of La Pampa Province (Argentina) are analyzed by mean of surveys. These are long tradition family enterprises (2.5 man equivalent) with owners (average 53.3 years old) that believe in the continuity of their farms. The educational level is very low (about 80 percent are real or functional illiterates), although 46 percent of their inheritors had completed the primary school and 15 percent had completed the high school. Technical assistance is received mainly from governmental programs. Kids are the main sale product and about 18 percent of them are used for family feeding. Other source of income would be increased adding value by mean of handmade manufacture (cheese, hair, spinning, tan leather, etc.)Mediante encuesta se estudian las explotaciones caprinas del oeste pampeano (Argentina). Son empresas familiares (2,5 equivalentes hombre), de larga tradición cuyos responsables, de bastante edad (53,3 años), confían en la continuidad de las explotaciones. El nivel educativo es muy bajo (alrededor del 80 p.100 son analfabetos reales o funcionales), aunque entre los posibles herederos el 46 p.100 ha completado la escuela primaria y el 15 p.100 la secundaria. El apoyo técnico que reciben corresponde casi exclusivamente a programas estatales. El cabrito para venta es el principal producto registrándose un 18 p.100 de autoconsumo. Otras fuentes de ingreso podrían potenciarse agregándoles valor por medio de procesos artesanales de elaboración (quesos, hilado de pelo, curtidos de cueros, etc.)

    XMM-Newton monitoring of the close pre-main-sequence binary AK Sco. Evidence of tide-driven filling of the inner gap in the circumbinary disk

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    AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R-* at periastron passage. The presence of a dense (n(e) similar to 10(11) cm(-3)) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of similar to 3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T similar to 6.4 x 10(6) K and it is found that the N-H column density rises from 0.35 x 10(21) cm(-2) at periastron to 1.11 x 10(21) cm(-2) at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s(-1) in the Nv line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst

    A metapopulation approach to identify targets for Wolbachia-based dengue control

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    Over the last decade, the release of Wolbachia-infected Aedes aegypti into the natural habitat of this mosquito species has become the most sustainable and long-lasting technique to prevent and control vector-borne diseases, such as dengue, zika, or chikungunya. However, the limited resources to generate such mosquitoes and their effective distribution in large areas dominated by the Aedes aegypti vector represent a challenge for policymakers. Here, we introduce a mathematical framework for the spread of dengue in which competition between wild and Wolbachia-infected mosquitoes, the cross-contagion patterns between humans and vectors, the heterogeneous distribution of the human population in different areas, and the mobility flows between them are combined. Our framework allows us to identify the most effective areas for the release of Wolbachia-infected mosquitoes to achieve a large decrease in the global dengue prevalence. © 2022 Author(s)

    Diet digestibility and production performance in dairy goats consuming plant oils

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    The aim of this study was to investigate the effects of differently unsaturated vegetable oils added to dairy goat diets on apparent digestibility and performance traits. Twelve Malagueña goats were randomly assigned to one of four treatments: no oil (CONTROL), 48 g/d of high oleic sunflower oil (GAO), regular sunflower oil (RSFO) or linseed oil (LIN). The basal diet was made of alfalfa hay and a pelleted concentrate, which included the respective oil and chromium as indicator. The experimental period lasted 21 days. The digestibility of dietary components, except for fat, did not differ between treatments (P > 0.05). Oil inclusion in the diet significantly (P < 0.05) increased fat digestibility. There were no significant differences (P > 0.05) in dry matter intake, milk yield and milk composition between treatments. It was concluded that moderate amounts of unsaturated plant oils can be added to dairy goat diets without negative effects on diet digestibility or performance traits

    Límites nutricionales para dietas de cabras lecheras en crecimiento

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    El objetivo del presente trabajo fue revisar el consumo de materia seca y las necesidades nutritivas de cabras lecheras de reposición estabuladas para establecer límites nutricionales aplicables a la formulación de dietas por programación lineal a mínimo coste. El diseño de dietas nutricionalmente adecuadas y económicas requiere que el nutricionista estime correctamente el consumo de materia seca y forraje y los aportes y las necesidades de nutrientes. La bibliografía revisada sugiere que el consumo total de materia seca de las cabras oscila entre los límites físico y fisiológico impuestos por la capacidad del tracto digestivo y las necesidades energéticas diarias. El efecto de llenado digestivo puede relacionarse con los carbohidratos estructurales de la dieta, mientras la saciedad metabólica se relaciona con la concentración energética de la dieta. El consumo mínimo de forraje necesario para mantener la salud ruminal es bajo, mientras que el consumo máximo de forraje está determinado probablemente por el contenido de fibra neutrodetergente de la dieta. Los aportes y las necesidades de energía y proteína calculadas según los dos sistemas de valoración más modernos son similares, por lo que es indistinto usar cualquiera de ambos para optimizar dietas. Las propuestas recientes para el cálculo de los aportes y las necesidades de calcio y fósforo ofrecen una mayor precisión
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