535 research outputs found

    Models of cuspy triaxial stellar systems. II. Regular orbits

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    In the first paper of this series we used the N--body method to build a dozen cuspy (gamma ~ 1) triaxial models of stellar systems, and we showed that they were highly stable over time intervals of the order of a Hubble time, even though they had very large fractions of chaotic orbits (more than 85 per cent in some cases). The models were grouped in four sets, each one comprising models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. The three models within each set, although different, had the same global properties and were statistically equivalent. In the present paper we use frequency analysis to classify the regular orbits of those models. The bulk of those orbits are short axis tubes (SATs), with a significant fraction of long axis tubes (LATs) in the E2 models that decreases in the E3 and E4 models to become negligibly small in the E5 models. Most of the LATs in the E2 and E3 models are outer LATs, but the situation reverses in the E4 and E5 models where the few LATs are mainly inner LATs. As could be expected for cuspy models, most of the boxes are resonant orbits, i.e., boxlets. Nevertheless, only the (x, y) fishes of models E3 and E4 amount to about 10 per cent of the regular orbits, with most of the fractions of the other boxlets being of the order of 1 per cent or less.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Societ

    Educación ambiental, vida en la naturaleza y ciencia escolar : Estado de situación y posibles estrategias de integración

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    La construcción de relaciones entre Vida en la Naturaleza, Educación Ambiental y Ciencia Escolar da lugar a un campo de trabajo educativo sobre el cual es posible trazar diversas configuraciones didácticas. Desde esta perspectiva, en el presente estudio se analiza el estado de situación de este campo relacional a partir de los resultados obtenidos de encuestas realizadas a estudiantes de Institutos Superiores de Formación Docente en Educación Física, para luego proponer posibles estrategias de intersección didáctica, siempre desde el marco referencial que brinda la tríada conceptual: motricidad, ambiente próximo y planetariedad. Las propuestas están dirigidas a enriquecer la formación inicial de futuros educadores así como también a contribuir en la formación permanente de docentes de diversos profesorados, pudiendo ser extendidas a facilitadores del ámbito educativo no forma

    Positivismo crimininológico, racismo y holocausto

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    Fil: Navone, Karina A. Universidad de Buenos Aires. Facultad de Derecho. Buenos Aires, Argentin

    Characterization and evaluation of a marine protected area: 'Tavolara - Punta Coda Cavallo' (Sardinia, NW Mediterranean)

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    Habitat mapping plays a key role in the management and conservation of natural systems. In protected areas, where sustainable development is always subordinate to conservation efforts, maps are largely used to represent habitats, development pressures, tourist facilities or legal restrictions such as the zoning of a protected area. Some authors have recently developed a methodology that allows the production of a set of maps for the management of marine protected areas. In this paper, we present the application of this methodology to the case study of the marine protected area 'Tavolara Punta Coda Cavallo'. © 2013 Copyright A. Rovere

    An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and ASteCA\texttt{ASteCA}

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    Several studies have been presented in the last few years applying some kind of automatic processing of data to estimate the fundamental parameters of open clusters. These parameters are later on employed in larger scale analyses, for example the structure of the Galaxy's spiral arms. The distance is one of the more straightforward parameters to estimate, yet enormous differences can still be found among published data. This is particularly true for open clusters located more than a few kpc away. We cross-matched several published catalogues and selected the twenty-five most distant open clusters (>>9000 pc). We then performed a detailed analysis of their fundamental parameters, with emphasis on their distances, to determine the agreement between catalogues and our estimates.} Photometric and astrometric data from the Gaia EDR3 survey was employed. The data was processed with our own membership analysis code (pyUPMASK), and our package for automatic fundamental cluster's parameters estimation (ASteCA\texttt{ASteCA}). We find differences in the estimated distances of up to several kpc between our results and those catalogued, even for the catalogues that show the best matches with ASteCA\texttt{ASteCA} values. Large differences are also found for the age estimates. As a by-product of the analysis we find that vd Bergh-Hagen 176 could be the open cluster with the largest heliocentric distance catalogued to date. Caution is thus strongly recommended when using catalogued parameters of open clusters to infer large-scale properties of the Galaxy, particularly for those located more than a few kpc away.Comment: Accepted for publication in A&

    Niveles de infección de helmintos de Rattus rattus (Rodentia: Muridae) en la ciudad de Corrientes, Argentina

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    The aim of this study was to describe the infection levels of helminths of Rattus rattus in Corrientes city, Corrientes Province, Argentina. In order to determine the role of rodents as potential reservoirs for zoonotic parasites, different indices of helminth infection were assessed with respect to sex, age, season and urban landscapes. A total of 107 individuals of R. rattus were examined. Seven species of helminths were found. The values of total prevalence, mean intensity and mean abundance were 68%, 20 and 13, respectively. Nippostrongylus brasiliensis was the species more prevalent and abundant. The results showed that the age of the rodents and the season of capture had effects on the helminth infection.El objetivo del trabajo fue describir los niveles de infección de Rattus rattus en la ciudad de Corrientes, provincia de Corrientes, Argentina. Con el objetivo de determinar el rol de los roedores como reservorios potenciales de parásitos zoonóticos, se analizó la distribución de helmintos respecto al sexo, edad, estación del año y ambientes urbanos. Un total de 107 individuos de R. rattus fueron examinados. Se identificaron siete especies de helmintos. Los valores de prevalencia total, intensidad media y abundancia media fueron 68%, 20 y 13, respectivamente. Nippostrongylus brasiliensis fue la especie más prevalente y abundante. Los resultados demostraron que la edad de los roedores y la estación del año tuvieron efectos en la infección con helmintos.Facultad de Ciencias Naturales y Muse

    Niveles de infección de helmintos de Rattus rattus (Rodentia: Muridae) en la ciudad de Corrientes, Argentina

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    The aim of this study was to describe the infection levels of helminths of Rattus rattus in Corrientes city, Corrientes Province, Argentina. In order to determine the role of rodents as potential reservoirs for zoonotic parasites, different indices of helminth infection were assessed with respect to sex, age, season and urban landscapes. A total of 107 individuals of R. rattus were examined. Seven species of helminths were found. The values of total prevalence, mean intensity and mean abundance were 68%, 20 and 13, respectively. Nippostrongylus brasiliensis was the species more prevalent and abundant. The results showed that the age of the rodents and the season of capture had effects on the helminth infection.El objetivo del trabajo fue describir los niveles de infección de Rattus rattus en la ciudad de Corrientes, provincia de Corrientes, Argentina. Con el objetivo de determinar el rol de los roedores como reservorios potenciales de parásitos zoonóticos, se analizó la distribución de helmintos respecto al sexo, edad, estación del año y ambientes urbanos. Un total de 107 individuos de R. rattus fueron examinados. Se identificaron siete especies de helmintos. Los valores de prevalencia total, intensidad media y abundancia media fueron 68%, 20 y 13, respectivamente. Nippostrongylus brasiliensis fue la especie más prevalente y abundante. Los resultados demostraron que la edad de los roedores y la estación del año tuvieron efectos en la infección con helmintos.Facultad de Ciencias Naturales y Muse
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