7,843 research outputs found

    SZ scaling relations in Galaxy Clusters: results from hydrodynamical N-body simulations

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    Observations with the SZ effect constitute a powerful new tool for investigating clusters and constraining cosmological parameters. Of particular interest is to investigate how the SZ signal correlates with other cluster properties, such as the mass, temperature and X-ray luminosities. In this presentation we quantify these relations for clusters found in hydrodynamical simulations of large scale structure and investigate their dependence on the effects of radiative cooling and pre-heating.Comment: 10 pages, 3 figures, LaTeX. To appear in proceedings of the JENAM 2002 conference. For a more detailed analysis see astro-ph/0308074, whose simulations supersede those presented at this conferenc

    A new genus of Prioninae (Coleoptera, Cerambycidae)

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    Neoma, a new genus of Cerambycidae (Coleoptera: Cerambycidae: Prioninae: Macrotomini) is described for Mallodonopsis corrosus Bates, 1879, compared to related genera (Aplagiognathus Thomson, 1861; Archodontes Lameere, 1903; and Mallodonopsis Thomson, 1861), and its tribal position discussed. A lectotype for Mallodonopsis corrosus is here designated with the species redescribed and figured

    The Behavior of HEGY Tests for Quarterly Time Series with Seasonal Mean Shifts

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    This paper studies the behavior of the HEGY statistics for quarterly data, for seasonal autoregressive unit roots, when the analyzed time series is deterministic seasonal stationary but exhibits a change in the seasonal pattern. As a by-product we analyze also the HEGY test for the nonseasonal unit root, the data generation process being trend stationary too. Our results show that when the break magnitudes are finite the HEGY test statistics are not asymptotically biased towards the non-rejection of the seasonal and nonseasonal unit root hypotheses. However, the finite sample power properties may be substancially affected, the behavior of the tests depending on the type of the break. Hence, our results are also useful to understand and to predict this behavior under several circumstances.seasonality; unit roots; strctural breaks; HEGY tests

    Emprendimiento y economía gig: un análisis bibliométrico

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    [EN] There is an increasing number of academic publications on studying the impact of the gig economy and digital platforms. Some of them involve entrepreneurship and business models. However, there is a lack of a global picture depicting the scientific structure of knowledge regarding the gig economy and entrepreneurship. This paper presents a conceptual, intellectual, and social bibliometric overview, using Bibliometrix and Biblioshiny (R-packages). To this end, total of 345 published articles were analyzed, covering 245 sources, 44 countries and 751 authors. There are several important findings: five main clusters emerged from the study (Self-employment and social economy; Sharing economy and sustainable development; Entrepreneurship and innovation; Gig economy and platform economy; and Digitalization); the main themes that emerge deal with sharing, gig, and platform economy, digitalization, teleworking, career participation and platforms; finally, gig workers are key for developing strategies, policies, and actions to achieve a social welfare through entrepreneurship in the platform ecosystem. It is also important to highlight the role of communities and social capital in the development of sustainable collaborative initiatives through digital entrepreneurship.[ES] Existe un número cada vez mayor de publicaciones académicas sobre el estudio del impacto de la economía gig y las plataformas digitales. Algunos de ellos incluyen el espíritu emprendedor y el modelo de negocio. Sin embargo, como falta una imagen global que describa la estructura científica del conocimiento con respecto a la economía gig y el emprendimiento, este artículo presenta una descripción bibliométrica conceptual, intelectual y social, utilizando Bibliometrix y Biblioshiny (paquetes R). Para ello, analizó un total de 345 artículos, que abarcan 245 fuentes, 44 países y 751 autores. Hay varios hallazgos importantes: cinco grupos principales surgieron del estudio (Autoempleo y economía social; Economía compartida y desarrollo sostenible; Emprendimiento e innovación; Economía Gig y economía de plataformas; y Digitalización); los principales temas que surgen tratan sobre el intercambio, la economía gig y las plataformas, la digitalización, el teletrabajo, la participación profesional y las plataformas; finalmente, los trabajadores gig son clave para desarrollar estrategias, políticas y acciones para lograr un bienestar social a través del emprendimiento en el ecosistema de las plataformas digitales. También es importante destacar el papel de las comunidades y el capital social en el desarrollo de iniciativas colaborativas sostenibles a través del emprendimiento digital

    Efficiency decomposition for multi-level multi-components production technologies

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    This paper addresses the efficiency measurement of firms composed by multiple components, and assessed at different decision levels. In particular it develops models for three levels of decision/production: the subunit (production division/process), the DMU (firm) and the industry (system). For each level, inefficiency is measured using a directional distance function and the developed measures are contrasted with existing radial models. The paper also investigates how the efficiency scores computed at different levels are related to each other by proposing a decomposition into exhaustive and mutually exclusive components. The proposed method is illustrated using data on Portuguese hospitals. Since most of the topics addressed in this paper are related to more general network structures, avenues for future research are proposed and discussed.info:eu-repo/semantics/publishedVersio

    Understanding Urea Encapsulation in Different Clay Minerals as a Possible System for Ruminant Nutrition

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    Considering the challenges of urea administration due to the high ureolytic activity of the rumen and the importance of its use, as well as taking into account the relevance of sustainably exploiting the technological potential of biodiversity, this research studies the encapsulation of urea in different clay minerals (palygorskite (Pal), sepiolite (Sep), and Veegum® (V)) as an alternative for use as nonprotein nitrogen (NNP) sources. A method of incorporation was developed in which the encapsulation of urea was proven by X-ray diffraction; fibrous materials, Pal and Sep had similar characteristics due to the decrease in the relative plane intensity (011), suggesting a decrease in the order of their stacking due to the presence of urea on the surface or inside channels. By contrast, V showed a 7.74º reflection shift, suggesting an increase in basal spacing from 11.45 Å in V to 14.88 Å in the sample after urea encapsulation. By thermogravimetry, it was observed that the presence of urea did not change the mass-loss profiles but only increased the percentage of loss in respective events, indicating urea incorporation in the clay minerals. These results provide a promising alternative for administering NNP sources in the ruminant diet

    The negative influences of the new brazilian forest code on the conservation of riparian forests

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    More than one million hectares of riparian forests were degraded or altered in Mato Grosso State (Brazil) up to 2009. The aim of the research is to set a comparative scenario to show differences in the quantification of environmental liabilities in riparian forest areas resulting from the change in native vegetation protection rules due to the transition between Laws 4771/65 and 12651/2012. Data collection took place in a marginal stretch of Vermelho River in Rondonópolis County, Mato Grosso State. The following data set was taken into consideration: aerial images derived from unmanned aerial vehicle, Rapid Eye satellite images and orbital images hosted at Google Earth. The spatial resolution of those images was compared. The aerial photos composed a mosaic that was photo-interpreted to generate land use and occupation classes. The riparian forest areas of a rural property were used as parameter, and their environmental situation was compared in 05 meter and 100 meter strips. Thus, by taking into consideration the current rules, 23,501 m2 of area ceased to be an environmental liability within the riparian forest and became a consolidated rural area. According to the previous Forest Code, in a different scenario, that is, in a set of rural properties, the public authority would receive USD 68,600.00 in fines. The new Brazilian Forestry Code of 2012, which replaces the previous one made in 1965, exempts those responsible for rural property from regenerating previously deforested native vegetation — an obligation established by older Forest Code. We have shown that the new Forest Code has diminished the legal responsibility of the rural owners in relation to the maintenance of forest fragments in their properties
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