19,149 research outputs found

    Detectability of the First Cosmic Explosions

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    We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using 8\lesssim 8 per cent of total allocation time of the James Webb Space Telescope mission can provide us up to 915\sim 9-15 detectable PISNe per year.Comment: 9 pages, 8 figures. Minor corrections added to match published versio

    Interação insetos-sementes: o mutualismo é possível.

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    Nesta publicação encontram-se reunidas informações sobre insetos e sementes de Parkia multijuga, Coffea canephora e Gossypium thurberi, para produzir um quadro comparativo da interação entre esses grupos de espécies. Argumentou-se que, no período reprodutivo das plantas, a cooperação entre estes organismos pode ir além da polinização. Foi proposto que os insetos podem ser elementos chave na estratégia reprodutiva das plantas, contribuindo decisivamente para o sucesso da germinação e estabelecimento de novas plântulas.bitstream/item/24657/1/doc98-insetos-sementes.pd

    Three path interference using nuclear magnetic resonance: a test of the consistency of Born's rule

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    The Born rule is at the foundation of quantum mechanics and transforms our classical way of understanding probabilities by predicting that interference occurs between pairs of independent paths of a single object. One consequence of the Born rule is that three way (or three paths) quantum interference does not exist. In order to test the consistency of the Born rule, we examine detection probabilities in three path intereference using an ensemble of spin-1/2 quantum registers in liquid state nuclear magnetic resonance (LSNMR). As a measure of the consistency, we evaluate the ratio of three way interference to two way interference. Our experiment bounded the ratio to the order of 103±10310^{-3} \pm 10^{-3}, and hence it is consistent with Born's rule.Comment: 11 pages, 4 figures; Improved presentation of figures 1 and 4, changes made in section 2 to better describe the experiment, minor changes throughout, and added several reference

    Mercado e comercialização na ovinocultura de corte no Brasil.

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    Resumo: O objetivo deste artigo é apresentar os dados relativos ao mercado e à comercialização da carne ovina no Brasil. Especificamente destacam-se os principais estados produtores, a questão da importação, os preços praticados, a estrutura agrária brasileira como um fator significativo para análise deste setor produtivo e o mercado internacional da ovinocultura. Para tanto são utilizados dados do Instituto Brasileiro de Geografia e Estatística, da Organização das Nações Unidas para Agricultura e Alimentação e outras fontes secundárias especializadas no setor. Os países com o maior rebanho ovino no mundo são China, Índia e Austrália, respectivamente, e a produção de carne ovina está concentrada majoritariamente no continente asiático (52%). Os dados demonstram que o Brasil possui o rebanho ovino concentrado em alguns estados da região Nordeste e no Rio Grande do Sul, os preços aos produtores têm se mantido estáveis no último ano com uma leve tendência de alta, que há uma tendência para o desenvolvimento da indústria de abate e de processamento e, como consequência, uma aproximação ao mercado consumidor. No entanto, conclui-se que persistem entraves organizacionais que impedem o desenvolvimento do setor e que precisam ser superados com urgência. Abstract: The aim of this paper is to present data on the market and the commercialization of sheep meat in Brazil. Specifically we highlight the major producing states, the issue of importation, the prices, the Brazilian agrarian structure as a significant factor for the analysis of this sector and the international market. To achieve this goal, the data were provided by the Brazilian Institute of Geography and Statistics and by the United Nations Food and Agriculture and other specialized secondary sources. Countries with the largest sheep flock in the world are China, India and Australia, respectively, and the meat production is mainly concentrated in Asia (52%). The data show that Brazilian sheep flock are concentrated in a few states in the Northeast and Rio Grande do Sul, the producer prices have remained stable over the last year with a slight upward trend, there is a tendency for the development of slaughter and processing industry and, as a consequence, an approximation to the consumer market. However, it is concluded that organizational obstacles remain and hinder the development of the sector and they must be overcome urgently

    Desenvolvimento de marca para produtos rurais: um estudo multicasos em São Paulo e Mato Grosso do Sul.

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    Resumo: Este artigo objetiva analisar a proposta de valor decorrente da identidade de marcas desenvolvidas por produtores rurais no Brasil. A análise da identidade de marcas foi baseada no modelo de planejamento da identidade de Aaker (1996). A metodologia adotada foi o estudo de casos múltiplos junto a seis produtores rurais de alimentos que criaram suas próprias marcas. Os casos contemplam dois produtores de leite, um criador de suínos, um produtor de frutas, um produtor de mel e um produtor de cachaça orgânica. Os resultados apontam para marcas conscientes de suas responsabilidades com relação aos clientes, consumidores, meio ambiente e sociedade. [Development of trademark for farm products: a study multi-case in Brazil]. Abstract: This paper aims to examine the proposal of value from the identity of the brands of foods developed by farmers in Brazil. The analysis of the identity of the brands was based on the Aaker (1996) model. The methodology was the multicase studies with six food rural producers - two producers of milk, a pig farmer, a producer of fruit, a producer of honey and a producer of organic “caipirinha”. The results indicate that brand awareness of their responsibilities with respect to customers, consumers, environment and society

    Estudo da diversidade de begomovirus em tomateiro cultivado na região da caatinga do Brasil.

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    O presente trabalho teve como objetivo analisar a diversidade de begomovirus infectando tomateiro no Nordeste brasileiro.Resumo 673-

    Problematic clinical features of powered wheelchair users with severely disabling multiple sclerosis

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    This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2014 Informa UK Ltd.Purpose: The aim of this study is to describe the clinical features of powered wheelchair users with severely disabling multiple sclerosis (MS) and explore the problematic clinical features influencing prescription. Method: Retrospective review of electronic and case note records of recipients of electric-powered indoor/outdoor powered wheelchairs (EPIOCs) attending a specialist wheelchair service between June 2007 and September 2008. Records were reviewed by a consultant in rehabilitation medicine, data systematically extracted and entered into a computer database. Further data were entered from clinical records. Data were extracted under three themes; demographic, diagnostic, clinical and wheelchair factors. Results: Records of 28 men mean age 57 (range 37–78, SD 12) years and 63 women mean age 57 (range 35–81, SD 11) years with MS were reviewed a mean of 64 (range 0–131) months after receiving their wheelchair. Twenty two comorbidities, 11 features of MS and 8 features of disability were thought to influence wheelchair prescription. Fifteen users were provided with specialised seating and 46 with tilt-in-space seats. Conclusions: Our findings suggest that people with severe MS requiring an EPIOC benefit from a holistic assessment to identify problematic clinical features that influence the prescription of the EPIOC and further medical and therapeutic interventions

    Development of virus resistant transgenic papayas expressing the coat protein gene from a Brazilian isolate of Papaya ringspot virus.

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    Translatable and nontranslatable versions of the coat protein (cp) gene of a Papaya ringspot virus (PRSV) isolate collected in the state of Bahia, Brazil, were engineered for expression in Sunrise and Sunset Solo varieties of papaya (Carica papaya). The biolistic system was used to transform secondary somatic embryo cultures derived from immature zygotic embryos. Fifty-four transgenic lines, 26 translatable and 28 nontranslatable gene versions, were regenerated, with a transformation efficiency of 2.7%. Inoculation of cloned RO plants with PRSV BR, PRSV HA or PRSV TH, Brazilian, Hawaiian and Thai isolates, respectively, revealed !ines with mono-, double-, and triple-resistance. After molecular analysis and a pre!iminary agronomic evaluation, 13 RI and R2 populations were incorporated into the papaya-breeding program at Embrapa Cassava and Tropical Fruits, in Cruz das Almas, Bahia, Brazil. Additional keywords: Carica papaya, potyvirus, resistance, breeding, virus. Desenvolvimento de mamoeiros transgênicos resistentes a vírus expressando o gene da capa protéica de um isolado brasileiro de Papaya ringspot vírus Versões traduzíveis e não traduzíveis do gene da capa protéica (cp) de um isolado de Papaya ringspot virus (PRSV) coletado no Estado da Bahia, Brasil, foram produzidas para expressão nas variedades Sunrise e Sunset Solo de mamoeiro (Carica papaya). O sistema de biobalística foi utilizado para transformar embriões somáticos secundários derivados de embriões zigóticos imaturos. Cinqüenta e quatro linhas transgênicas, sendo 26 contendo versões traduzíveis e 28 contendo versões não traduzíveis do gene cp foram regeneradas, o que resultou em 2,7% de eficiência de transformação, quando considerado o número de linhas transgênicas obtidas por embrião zigótico imaturo excisado. Desafios de plantas RO com PRSV BR, PRSV HA ou PRSV TH, respectivamente isolado brasileiro, havaiano e tailandês, revelaram linhas com resistência a um, dois e três isolados de PRSV. Após análises moleculares e avaliação agronômica preliminar, 13 populações RI e R2 de mamoeiros transgênicos foram incorporadas ao programa de melhoramento genético da Embrapa Mandioca e Fruticultura, em Cruz das Almas, Bahia, Brasil. Palavras-chave adicionais: Carica papaya, potyvirus, resistência, melhoramento, PRSV
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