431 research outputs found

    New thought experiment to test the generalized second law of thermodynamics

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    We propose an extension of the original thought experiment proposed by Geroch, which sparked much of the actual debate and interest on black hole thermodynamics, and show that the generalized second law of thermodynamics is in compliance with it.Comment: 4 pages (revtex), 3 figure

    Patterns of wildlife hunting and trade by local communities in eastern Amazonian floodplains

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    Local people living in the Amazon rainforest rely heavily on wild meat as a source of protein and income. While the patterns and drivers of wildlife hunting and trade by local communities are well-known for upland forests, such aspects have been poorly explored in Amazonian floodplains. This study aims to describe wild meat hunting and trade patterns and assess the hunting dynamics of local communities in Amazonian floodplain areas. For this purpose, we interviewed 121 hunters in 36 communities living in white-water flooded forests in the lower Amazon River, Brazil. Thirty taxa were cited as hunted by interviewees, who used a repertoire of 13 hunting techniques. Aquatic and semi-aquatic taxa were the most prevalent, especially Hydrochoerus hydrochaeris, Cairina moschata, and Podocnemis unifilis. Eight taxa were cited as traded; wild meat was sold at 2.57 ± 2.22 USD/kg, while eggs of birds and turtles were sold at 0.37 ± 0.27 USD/unit. We found an inverted-U relationship between the body mass and the number of citations per taxa, with species weighing between 10-40 kg presenting the highest number of citations. The hunting patterns found here are different from those frequently found in the literature for upland environments. Understanding these hunting and trade patterns will help develop tailored wildlife conservation and management strategies for Amazonian floodplains

    Influência da variação da produtividade das usinas hidroelétricas no cálculo da energia firme

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    In the present work, the problem associated to the firm energy evaluation is treated as a non linear optimization model, which allows the representation of the productivity variation of the hydro plants. The proposed model takes into account the individualized representation of the plants and the historical series of flows since the month of January of 1931. The proposed optimization problem will be solved using the Primal-Dual Interior Point Method. A case study will be presented including the Brazilian Interconnected National System. The results obtained show that the proposed methodology is promising, since it presents an energy market value more realistic when compared with existing methodologies.No presente trabalho, o problema associado ao cálculo da energia firme é tratado como um modelo não linear de otimização, o que permite a representação da variação da produtividade das usinas. No modelo proposto é considerada a representação individualizada das usinas bem como a série histórica de vazões desde o mês de janeiro de 1931. O problema de otimização proposto é resolvido através do método primal-dual de pontos interiores. Adicionalmente, é apresentado um estudo de caso abrangendo o Sistema Interligado Nacional Brasileiro. Os resultados obtidos mostram que a metodologia proposta é promissora, tendo em vista que apresenta um valor de mercado de energia mais realista quando comparado com outras metodologias

    Shell sclerochronology and stable isotopes of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) from southern Brazil: : implications for environmental and archaeological studies

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    We conduct the first stable isotopic and sclerochronological calibration of the bivalve Anomalocardia flexuosa (Linnaeus, 1767) in relation to environmental variables in a subtropical coastal area of southern Brazil. We investigate incremental shell growth patterns and δ18O and δ13C values of modern specimens collected alive from the Laguna Lagoonal System (LLS). As shells of Anomalocardia flexuosa are also the main components of pre-Columbian archaeological shell mounds and middens distributed along the Brazilian coastline, late Holocene archaeological specimens from a local shell mound (Cabeçuda) were selected to compare their stable carbon and oxygen isotopes with those of modern specimens. Shell growth increments, δ18O and δ13C values respond to a complex of environmental conditions, involving, for example, the effects of temperature and salinity. The isotopic information extracted from archaeological specimens from Cabeçuda shell midden in the LLS indirectly indicates that environmental conditions during the late Holocene were different from present day. In particular, intra-shell δ18O and δ13C values of archaeological shells reveal a stronger marine influence at 3 ka cal BP, which is in contrast to the seasonal freshwater/seawater balance that currently prevails at the LLS

    Poluição do ar e doenças respiratórias alérgicas em escolares

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    Estudo sobre a prevalência de doenças respiratórias alérgicas em escolares de seis a sete anos de idade, relacionadas com indicadores de poluição atmosférica. Questionário baseado no International Study of Asthma and Allergies in Childhood foi aplicado aos pais de alunos de escolas públicas, situadas em regiões urbanas diferentes, quanto ao fluxo de veículos. Houve correlação positiva entre frequência mensal de rinite e concentração de poluentes e negativa com a umidade relativa do ar. Resultados indicam que, mesmo com níveis de poluentes menores que os permitidos pela legislação, a prevalência de asma, rinite e sintomas associados tendeu a ser maior em alunos da escola da região central, onde há intenso tráfego veicular

    The 2nd competition on counter measures to 2D face spoofing attacks

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    Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. I. Chingovska, J. Yang, Z. Lei, D. Yi, S. Z. Li, O. Kahm, C. Glaser, N. Damer, A. Kuijper, A. Nouak, J. Komulainen, T. Pereira, S. Gupta, S. Khandelwal, S. Bansal, A. Rai, T. Krishna, D. Goyal, M.-A. Waris, H. Zhang, I. Ahmad, S. Kiranyaz, M. Gabbouj, R. Tronci, M. Pili, N. Sirena, F. Roli, J. Galbally, J. Fiérrez, A. Pinto, H. Pedrini, W. S. Schwartz, A. Rocha, A. Anjos, S. Marcel, "The 2nd competition on counter measures to 2D face spoofing attacks" in International Conference on Biometrics (ICB), Madrid (Spain), 2013, 1-6As a crucial security problem, anti-spoofing in biometrics, and particularly for the face modality, has achieved great progress in the recent years. Still, new threats arrive inform of better, more realistic and more sophisticated spoofing attacks. The objective of the 2nd Competition on Counter Measures to 2D Face Spoofing Attacks is to challenge researchers to create counter measures effectively detecting a variety of attacks. The submitted propositions are evaluated on the Replay-Attack database and the achieved results are presented in this paper.The authors would like to thank the Swiss Innovation Agency (CTI Project Replay) and the FP7 European TABULA RASA Project4 (257289) for their financial support

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
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