5,181 research outputs found

    Compatible finite element spaces for geophysical fluid dynamics

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    Compatible finite elements provide a framework for preserving important structures in equations of geophysical uid dynamics, and are becoming important in their use for building atmosphere and ocean models. We survey the application of compatible finite element spaces to geophysical uid dynamics, including the application to the nonlinear rotating shallow water equations, and the three-dimensional compressible Euler equations. We summarise analytic results about dispersion relations and conservation properties, and present new results on approximation properties in three dimensions on the sphere, and on hydrostatic balance properties

    Modeling Changes in Measured Conductance of Thin Boron Carbide Semiconducting Films Under Irradiation

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    Semiconducting, p-type, amorphous partially dehydrogenated boron carbide films (a-B10C2+x:Hy) were deposited utilizing plasma enhanced chemical vapor deposition (PECVD) onto n-type silicon thus creating a heterojunction diode. A model was developed for the conductance of the device as a function of perturbation frequency (��) that incorporates changes of the electrical properties for both the a-B10C2+x:Hy film and the silicon substrate when irradiated. The virgin model has 3 independent variables (R1, C1, R3), and 1 dependent variable (��). Samples were then irradiated with 200 keV He+ ions, and the conductance model was matched to the measured data. It was found that initial irradiation (0.1 displacements per atom (dpa) equivalent) resulted in a decrease in the parallel junction resistance parameter from 6032 Ω to 2705 Ω. Further irradiation drastically increased the parallel junction resistance parameter to 39000 Ω (0.2 dpa equivalent), 77440 Ω (0.3 dpa equivalent), and 190000 Ω (0.5 dpa equivalent). It is believed that the initial irradiation causes type inversion of the silicon substrate changing the original junction from a p-n to a p-p+ with a much lower barrier height leading to a lower junction resistance component between the a-B10C2+x:Hy and irradiated silicon. Additionally, it was found that after irradiation, a second parallel resistor and capacitor component is required for the model, introducing 2 additional independent variables (R2, C2). This is interpreted as the junction between the irradiated and virgin silicon near ion end of range

    Assessment of the conservation status of natural and semi-natural patches associated with urban areas through habitat suitability indices

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    Urban environments rely on the surrounding natural ecosystems remnants as providers of ecosystem functions, therefore these areas not only support a unique biodiversity but also have a social value for maintaining public health and wellbeing. For this reason, urbanization is considered to be one the biggest threats to ecosystems, leading to native biodiversity simplification and, thus, to a detriment of the provided ecosystem services. Moreover, this change in land use results in high levels of landscape fragmentation and modification in areas surrounding the habitat remnants which, in consequence, become inadequate for many native species. In this context, it is important that urban planners have the information to assess the possible consequences of future changes in land use in order to increase the landscape chances of supporting both, native biodiversity and the needs of a growing human population. The objective of the present work is to evaluate the ecological integrity of natural and semi-natural vegetation patches immersed in an urban area in order to generate a conceptual framework for landscape assessment that allows urban planners to envision the best choice for city development at a given place. To do so, we developed a quantitative integral environmental evaluation index that includes ecological characterization, geological characterization, and environmental characterization (presence of anthropic disturbance) of the assessed area. We conclude that the index we have generated in this work is suitable to be used as a management tool to allow an unbiased valuation and to identify managing situations that require a short term response.Fil: Natale, Evangelina Sandra. Fundación Conservación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Villalba, G.. Fundación Conservación y Desarrollo; ArgentinaFil: Junquera, J. E.. Fundación Conservación y Desarrollo; ArgentinaFil: Zalba, Sergio Martín. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Scinax granulatus (NCN). Argentina: Buenos Aires

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    Partido de General Pueyrredon. Sierra de Los Padres (37° 56' 25"S 57 °47' 41" W). 24 July 2010. L. E.Vega & P. J.Bellagamba. Verified by J. Faivovich. Herpetological Collection of Laboratorio Vertebrados, Departamento de Biología, Universidad Nacional de Mar del Plata (UNMdP 1809, UNMdP 1810). Two adult individuals were captured under rocks in the ridge of mountains of Sierra de los Padres of the Tandilia Mountain Range System. Another five individuals were detected inactive in similar microhabitats (under rocks). Barrasso and Cajade (Barraso, D. and R. Cajade. 2007. Geographic distribution: Scinax granulatus. Herpetol. Rev. 38: 1) pointed out that Gallardo mentioned two specimens from Sierra de la Ventana, but such citation is not supported by voucher specimens, therefore this is the first documentation of this frog inhabiting mountain environments at 170 MASL...Fil: Vega, Laura Estela. Universidad Nacional de Mar del Plata. Instituto de Biología; ArgentinaFil: Bellagamba, Patricio J.. Universidad Nacional de Mar del Plata. Instituto de Biología; ArgentinaFil: Stellatelli, Oscar Aníbal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de Mar del Plata. Instituto de Biología; ArgentinaFil: Natale, Guillermo Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentin

    Relating a gluon mass scale to an infrared fixed point in pure gauge QCD

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    We show that in pure gauge QCD (or any pure non-Abelian gauge theory) the condition for the existence of a global minimum of energy with a gluon (gauge boson) mass scale also implies the existence of a fixed point of the β\beta function. We argue that the frozen value of the coupling constant found in some solutions of the Schwinger-Dyson equations of QCD can be related to this fixed point. We also discuss how the inclusion of fermions modifies this property.Comment: 4 pages, Revtex - Added some clarifying comments and new reference

    Facilitating Lexical Acquisition in Beginner Learners of Italian Through Task-Induced Involvement Load

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    This empirical study explores the facilitation of lexical acquisition and retention through an incidental experiment examining the effect of Involvement Load on Italian vocabulary growth among beginner learners. The experiment, with a pre-test/post-test design investigates the facilitative effects of elaborate processing on L2 lexical acquisition and retention. Participants in sections of the same first-year Italian course were divided into one of five groups consisting of a Control Group and four Treatment groups. Treatment groups were divided based on level of Involvement (Laufer & Hulstijn, 2001) such that some groups processed target words elaborately (Craik, 2002; Lockhart, 2002) through vocabulary exercises while others completed low involvement activities limited to comprehension of the lyrics. The fifth group constituted the Control. In terms of lexical gains, it was hypothesized that (i) if medium was held constant (Music or Poem), the High Involvement groups would outperform Low involvement groups. The Vocabulary Knowledge Scale (VKS) (Wesche & Paribakht, 1993) was administered at pre-test and at four and eight weeks following pre-test respectively. Mean scores at post-test and delayed post-test in addition to ANOVA indicated that participants in the High Involvement groups outperformed participants in Low Involvement groups (p=0.017). The facilitative role of involvement load is discussed in light of pedagogical implications for the language learning classroom
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