3,793 research outputs found

    On Useful Conformal Tranformations In General Relativity

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    Local conformal transformations are known as a useful tool in various applications of the gravitational theory, especially in cosmology. We describe some new aspects of these transformations, in particular using them for derivation of Einstein equations for the cosmological and Schwarzschild metrics. Furthermore, the conformal transformation is applied for the dimensional reduction of the Gauss-Bonnet topological invariant in d=4d=4 to the spaces of lower dimensions.Comment: 17 pages, LaTeX. The paper is intended mainly for pedagogical purposes and represents a collection of exercises concerning local conformal transformations and dimensional reduction. To be published in "Gravitation and Cosmology

    Symmetries and Ambiguities in the linear sigma model with light quarks

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    We investigate the role of undetermined finite contributions generated by radiative corrections in a SU(2)×SU(2)SU(2)\times SU(2) linear sigma model with quarks. Although some of such terms can be absorbed in the renormalization procedure, one such contribution is left in the expression for the pion decay constant. This arbitrariness is eliminated by chiral symmetry.Comment: 9 pages. Added references through the text; an author was added due to an important contribution; corrected typos; the title also was changed. Submitted to Modern Physics Letter

    Comparative susceptibility of southern and western corn rootworm adults and larvae to vATPase-A and Snf7 dsRNAs.

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    Corn rootworms (CRW) are the most important corn pests in the U.S. Corn Belt. Damage is caused by larval feeding on the plant roots. RNAi has been studied in CRW and has proven to be effective for the management of this insect with effects on both larval and adult stages. The objective of this study was to determine comparative susceptibility of adult and larva of Southern Corn Rootworm (SCR) and Western Corn Rootworm (WCR) to two different lethal RNAi target genes (vacuolar (v)-ATPase-A and Snf7). Adults and larvae were exposed to dsRNAs overlaid on artificial diet five times every other day. WCR larval susceptibility to vATPase-A was approximately 4-fold more tolerant than SCR, but were similar for Snf7 (2.6 ng/cm2 for both species). For adults, LC50s were generally higher for vATPase-A dsRNA relative to larvae with a 20-fold higher LC50 for WCR (SCR=33.3 ng/cm2; WCR=657.3 ng/cm2) relative to Snf7 dsRNAs (SCR=13.2 ng/cm2; WCR=60.2 ng/cm2). Gene silencing was also evaluated in adults and larvae exposed to the LC50 dsRNAs, and gene knockdown ranged from 48% up to 83% in adults fed for eight days in dsRNA, and from 55% to 89% in larvae fed for 24, 48 and 72 h, compared to control treatments. This is the first study to report LC50 values for dsRNA in WCR and SCR adults. The results indicate that both larvae and adults of both species were affected by vATPase-A and Snf7 dsRNAs suggesting that RNAi for the management of CRW should be considered for both stages

    Desenvolvimento do agroturismo em Cachoeiras de Macacu, RJ: subsídios ao planejamento da atividade agroturística associada à produção agropecuária de base familiar.

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    O Município de Cachoeiras de Macacu está situado numa região que exibe grande riqueza de atributos naturais, apresentando vocação para a exploração de atividades turísticas de cunho rural e ecológico, e ainda, por desenvolver agropecuária expressiva, apresenta potencial para explorar o segmento do turismo associado às atividades produtivas do meio rural (agricultura, pecuária e silvicultura), o agroturismo. Entretanto, para que a atividade seja sustentável, requer planejamento, sendo necessário um estudo prévio de viabilidade, que considere aspectos físicos, sociais, culturais, econômicos e ambientais. Face a isso, este estudo teve por objetivo fazer um levantamento diagnóstico sobre as potencialidades e limitações do Município de Cachoeiras de Macacu em relação ao agroturismo; e com base nisso, elaborar um plano preliminar para subsidiar o desenvolvimento da atividade. Para tanto, foram compilados dados secundários e primários. Os dados secundários consultados referem-se a resultados de pesquisas e estudos realizados nos últimos 10 anos na região pela Embrapa Solos e outras instituições de pesquisa e/ou ensino, e de projetos que complementam e integram temas de interesse comum. Os dados primários foram coletados junto aos atores locais (produtores rurais familiares e seus representantes, funcionários de instituições públicas, empreendedores rurais, proprietários de meios de hospedagem, entre outros), por meio de campanhas de campo realizadas entre 2012 e 2014, nas comunidades rurais produtivas com base na agricultura familiar. O conjunto de dados inventariados e a síntese do diagnóstico obtido serviram de base para a elaboração do plano preliminar. A presente versão intitulada: "Plano Preliminar para o Desenvolvimento do Agroturismo em Cachoeiras de Macacu, RJ" representa um primeiro passo para orientar o planejamento do agroturismo integrado à produção agropecuária de base familiar no município. Sua efetivação envolve os poderes públicos estaduais e municipais e deve ser impulsionado pela comunidade, para garantir que a atividade se desenvolva em harmonia com suas expectativas e anseios.bitstream/item/142637/1/BPD-244-Desenv-Agroturismo-Cach-Macacu.pd

    Coeficiente de parentesco entre as principais cultivares de feijão do tipo carioca.

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    Foi obtida a genealogia das principais cultivares de feijão tipo carioca em uso no Brasil e estimado o grau de parentesco entre elas. Foi obtida a genealogia de 15 cultivares

    1H, 13C, 15N backbone and IVL methyl group resonance assignment of the fungal β-glucosidase from Trichoderma reesei

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    β-glucosidases have received considerable attention due to their essential role in bioethanol production from lignocellulosic biomass. β-glucosidase can hydrolyse cellobiose in cellulose degradation and its low activity has been considered as one of the main limiting steps in the process. Large-scale conversions of cellulose therefore require high enzyme concentration which increases the cost. β-glucosidases with improved activity and thermostability are therefore of great commercial interest. The fungus Trichoderma reseei expresses thermostable cellulolytic enzymes which have been widely studied as attractive targets for industrial applications. Genetically modified β-glucosidases from Trichoderma reseei have been recently commercialised. We have developed an approach in which screening of low molecular weight molecules (fragments) identifies compounds that increase enzyme activity and are currently characterizing fragment-based activators of TrBgl2. A structural analysis of the 55 kDa apo form of TrBgl2 revealed a classical (α/β)8-TIM barrel fold. In the present study we present a partial assignment of backbone chemical shifts, along with those of the Ile (I)-Val (V)-Leu (L) methyl groups of TrBgl2. These data will be used to characterize the interaction of TrBgl2 with the small molecule activators

    Tachyon Effective Dynamics and de Sitter Vacua

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    We show that the DBI action for the singlet sector of the tachyon in two-dimensional string theory has a SL(2,R) symmetry, a real-time counterpart of the ground ring. The action can be rewritten as that of point particles moving in a de Sitter space, whose coordinates are given by the value of the eigenvalue and time. The symmetry then manifests as the isometry group of de Sitter space in two dimensions. We use this fact to write the collective field theory for a large number of branes, which has a natural interpretation as a fermion field in this de Sitter space. After spending some time building geometrical insight on facts about the condensation process, the state corresponding to a sD-brane is identified and standard results in quantum field theory in curved space-time are used to compute the backreaction of the thermal background.Comment: 28 pages, 1 eps figure. Uses graphicx, setspace. v2:corrected typos, added references, clarified discussion on backreactio

    CALPOT, fosfato e silício co-aplicados ao solo para a cultura da soja.

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    Visando fornecer Ca, Mg, K e melhorar a disponibilidade de P para a soja, foi aplicado CALPOT e escória de siderurgia. As fontes também possuem poder de neutralização e diminuição da acidez do solo. Os tratamentos aplicados constituíram-se de: 1) Testemunha; 2) CALPOT + P + Si; 3) CALPOT + P; 4) CALPOT + Si; 5) Si + P; 6) Calcário; 7) CALPOT. Os cátions básicos Ca, Mg e K foram aplicados como CALPOT, (calcário dolomítico + cloreto de potássio) com dose calculada para se atingir um índice de saturação no solo equivalente a: 50% de Ca, 10% de Mg, e 3% de K. O P aplicado foi de 100 kg ha-1 e Si foi duas vezes a dose de P (200 kg ha-1). O tratamento CALPOT + P + Si atingiu o equilíbrio em bases como pré-estabelecido, aumentou disponibilidade de fósforo no solo, obteve maior peso de folhas e matéria seca total. A co-aplicação dos elementos não impossibilitou o fornecimento de fósforo e demais nutrientes à planta
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