1,383 research outputs found

    Inflated Beta Distributions

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    This paper considers the issue of modeling fractional data observed in the interval [0,1), (0,1] or [0,1]. Mixed continuous-discrete distributions are proposed. The beta distribution is used to describe the continuous component of the model since its density can have quite diferent shapes depending on the values of the two parameters that index the distribution. Properties of the proposed distributions are examined. Also, maximum likelihood and method of moments estimation is discussed. Finally, practical applications that employ real data are presented.Comment: 15 pages, 4 figures. Submitted to Statistical Paper

    Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters II. Berkeley 23, King 1, NGC 559, NGC 6603 and NGC 7245

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    Context: Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims: We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. Methods: We acquired medium-resolution spectra (R~8000) in the infrared region Ca II triplet lines (~8500 AA) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5~m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca II lines and metallicity were also used to derive the metallicity for each cluster. Results: We obtain = 48.6+/-3.4, -58.4+/-6.8, 26.0+/-4.3 and -65.3+/-3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603 and NGC 7245, respectively. We found [Fe/H] =-0.25+/-0.14 and -0.15+/-0.18 for NGC 559 and NGC 7245, respectively. Berkeley 23 has a low metallicity, [Fe/H] =-0.42+/-0.13, similar to other open clusters in the outskirts of the Galactic disc. In contrast, we derived a high metallicity ([Fe/H] =+0.43+/-0.15) for NGC 6603, which places this system among the most metal rich known open clusters. To our knowledge, this is the first determination of radial velocities and metallicities from spectroscopy for these clusters, except NGC 6603, for which radial velocities had been previously determined. We have also analysed ten stars in the line of sight to King 1. Because of the large dispersion obtained in both radial velocity and metallicity, we cannot be sure that we have sampled true cluster members.Comment: 10 pages, 5 figures, accepted for publication in A&A (minor modifications

    Pinworms of the red howler monkey (Alouatta seniculus) in Colombia. Gathering the pieces of the pinworm-primate puzzle

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    Pinworms of primates are believed to be highly host specific parasites, forming co-evolutionary associations with their hosts. In order to assess the strength and reach of such evolutionary links, we need to have a broad understanding of the pinworm diversity associated with primates. Here, we employed an integrative taxonomic approach to assess pinworm diversity in red howler monkeys in Colombia. Molecular and morphological evidence validate the presence of at least four different species of Trypanoxyuris occurring in red howler monkeys: T. minutus, a widely distributed species, and three new species, T. seunimiii n. sp., T. kemuimae n. sp. and T. kotudoi n. sp. The mitochondrial COI gene and the 28S ribosomal gene were used for phylogenetic assessments through Bayesian inference. The three new species were morphologically distinct and formed reciprocally monophyletic lineages. Further molecular lineage subdivision in T. minutus and T. kotudoi n. sp. without morphological correspondence, suggests the potential scenario for the existence of cryptic species. Phylogenetic relationships imply that the different species of Trypanoxyuris occurring in each howler monkey species were acquired through independent colonization events. On-going efforts to uncover pinworm diversity will allow us to test the degree of host specificity and the co-phylogenetic hypothesis, as well as to further unravel the primate-pinworm evolutionary history puzzle

    Estimating networks of sustainable development goals

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    An increasing number of researchers and practitioners advocate for a systemic understanding of the Sustainable Development Goals (SDGs) through interdependency networks. Ironically, the burgeoning network-estimation literature seems neglected by this community. We provide an introduction to the most suitable estimation methods for SDG networks. Building a dataset with 87 development indicators in four countries over 20 years, we perform a comparative study of these methods. We find important differences in the estimated network structures as well as in synergies and trade-offs between SDGs. Finally, we provide some guidelines on the potentials and limitations of estimating SDG networks for policy advice

    II Workshop on Modeling and Simulation for Science and Engineering

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    II Workshop on Modeling and Simulation for Science and Engineering (II WMSSE) was a conference conducted at Universidad Tecnológica de Bolívar, in the city of Cartagena de Indias, Colombia, on September 24, 25 and 26, 2019. There, works in several topics of science, technology and engineering were presented. Specially, the participants of conference wanted to bring some solutions to the actual industrial requirements such as improvement and optimization of the heat transfer equipment, electronic devices, system control by mean of computational modeling. Also, dynamic system control was widely used for the prediction of power flow market, diffusion of bacteria in coffee production, stress concentration in industrial machines, analysis of population dynamics, model of hydrological and pluviometric networks, encryption for intercommunication of substation control centers, and others

    Situación adidáctica en entornos informáticos sobre sistema de numeración decimal

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    Esta conferencia recoge alguno de los avances del trabajo de grado que se viene adelantando como prerrequisito para optar por el título de Licenciatura en Educación Básica con énfasis en Matemáticas de la Universidad de Valle, donde se propone un diseño, implementación, análisis y evaluación de una secuencia didáctica mediante una serie de actividades en Geogebra, que conducen a la apropiación, por parte del estudiante, del concepto de sistema de numeración decimal. De esta manera propiciar al estudiante una situación de aprendizaje didáctica y darle la oportunidad de construir sus propios conocimientos del concepto referente al sistema de numeración decimal, mediante el análisis, la exploración, y una gestión didáctica. Además, que el estudiante pueda mediante la experimentación con las matemáticas, visualizar conceptos abstractos mediante una constante conexión conceptual con el nuevo concepto asimilado y los conocimientos previos

    The use of cassava products in animal feeding

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