1,767 research outputs found

    On the effective action of the vacuum photon splitting in Lorentz-violating QED

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    We consider one-loop radiative corrections from Lorentz- and CPT- violating extended QED to address the specific problem of finding explicitly an effective action describing amplitude of photon triple splitting. We show that it is not possible to find a nonzero photon triple splitting effective action, at least by using the derivative expansion method (at zero external momenta), up to leading order in the Lorentz- and CPT- violating parameter.Comment: 4 pages, version to appear in EP

    Biological control of Prays Oleae (BERN.) By chrysopids in tras-os-Montes region (Northeastern Portugal)

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    A study was carried out in an olive grove in the Tras-os-Montes region, in the period 1993 to 1996 to establish the rate of predation of chrysopids on Prays oleae (Bern.) eggs. Data on a trial conducted in 1996 to evaluate the effectiveness of field releases of Chrysoperla carnea (Steph.) in controlling eggs of the carpophagous generation of the pest are also reported. Six species of Chrysopidae have been collected. The most abundant were C. carnea and Mallada flavifrons (Brauer) which together represented about 74% of total captures. The main period of adult catches occurred between July and October. The rate of predation by chrysopids on P. oleae eggs varied among different generations of the pest and in different years, reaching 34% for the carpophagous generation in 1996. The potential damage that might be expected from the studied population of P. oleae was almost halved by releasing 360 larvae of C. carnea per tree.PAMAF lED no 611

    Time-Dependent Variational Analysis of Josephson Oscillations in a Two-component Bose-Einstein Condensate

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    The dynamics of Josephson-like oscillations between two coupled Bose-Einstein condensates is studied using the time-dependent variational method. We suppose that the quantum state of the condensates is a gaussian wave-packet which can translate and perform breathing shape oscillations. Under this hypotheses we study the influence of these degrees of freedom on the tunneling dynamics by comparing the full-model with one where these degrees of freedom are ``frozen'' at its equilibrium values. The result of our calculation shows that when the traps are not displaced the two models agree, whereas when they are, the models differ considerably, the former being now closer to its linear approximation.Comment: 10 pages, 2 figure

    Proximity-to-goal as a constraint on patterns of behaviour in attacker-defender dyads in team games

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    Abstract The aim of this study was to determine whether spatiotemporal interactions between footballers and the ball in 1 vs. 1 sub-phases are influenced by their proximity to the goal area. Twelve participants (age 15.3 +/- 0.5 years) performed as attackers and defenders in 1 vs. 1 dyads across three field positions: (a) attacking the goal, (b) in midfield, and (c) advancing away from the goal area. In each position, the dribbler was required to move beyond an immediate defender with the ball towards the opposition goal. Interactions of attacker-defender dyads were filmed with player and ball displacement trajectories digitized using manual tracking software. One-way repeated measures analysis of variance was used to examine differences in mean defender-to-ball distance after this value had stabilized. Maximum attacker-to-ball distance was also compared as a function of proximity-to-goal. Significant differences were observed for defender-to-ball distance between locations (a) and (c) at the moment when the defender-to-ball distance had stabilized (a: 1.69 +/- 0.64 m; c: 1.15 +/- 0.59 m; P < 0.05). Findings indicate that proximity-to-goal influenced the performance of players, particularly when attacking or advancing away from goal areas, providing implications for training design in football. In this study, the task constraints of football revealed subtly different player interactions than observed in previous studies of dyadic systems in basketball and rugby union

    Integrated leaching and separation of metals using mixtures of organic acids and ionic liquids

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    In this work, the aqueous phase diagram for the mixture of the hydrophilic tributyltetradecyl phosphonium ([P44414]Cl) ionic liquid with acetic acid (CH3COOH) is determined, and the temperature dependency of the biphasic region established. Molecular dynamic simulations of the [P44414]Cl + CH3COOH + H2O system indicate that the occurrence of a closed "type 0" biphasic regime is due to a "washing-out" phenomenon upon addition of water, resulting in solvophobic segregation of the [P44414]Cl. The solubility of various metal oxides in the anhydrous [P44414]Cl + CH3COOH system was determined, with the system presenting a good selectivity for CoO. Integration of the separation step was demonstrated through the addition of water, yielding a biphasic regime. Finally, the [P44414]Cl + CH3COOH system was applied to the treatment of real waste, NiMH battery black mass, being shown that it allows an efficient separation of Co(II) from Ni(II), Fe(III) and the lanthanides in a single leaching and separation step.publishe

    Relatório técnico da Embrapa Gado de Leite 1999-2000.

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    Núcleos temáticos:Resultados de pesquisa por Núcleo Temático da Embrapa Gado de Leite; Núcleo Temático Biogenética Animal Projetos: Marcadores genéticos associados às características de resistência a endo e ectoparasitos e ao estresse térmico em bovinos de leite; Organização do sistema de avaliação genética das raças de bovinos de leite no Brasil; Otimização do ganho genético em rebanhos zebus leiteiros; Otimização das técnicas de transferência de embrião e produção in vitro de embrião na raça Gir; SeJeção nas raças Holandesa e Girolando, Publicações geradas pelo Núcleo Temático; Núcleo Temático Biogenética de Forrageiras Projetos: Banco Ativo de Germoplasma de Capim-elefante e Alfafa; Identificação e ava\iação in vitro de clones de capim-elefante para tolerância ao estresse hídrico; Melhoramento genético do capim-elefante (P. purpureum Schum.) e da alfafa (M. sativa L.) para diferentes condições edafoclimáticas; Publicações geradas pelo Núcleo Temático; Núcleo Temático Sistemas de Alimentação -Projetos: Avaliação de milho e sorgo para silagem; Desenvolvimento de cultivares de sorgo; Publicações geradas pelo Nucleo Temático; Núcleo Temático Sustentabilidade da Atividade Leiteira -Projetos: Estratégias de manejo nutricional de vacas leiteiras em pastagens de capim-elefante; Inserção da fixação biológica de nitrogênio na recuperação de áreas degradadas e na sustentabilidade e produtividade de solos tropicais; Sistemas alternativos de produção de leite a pasto sob manejo intef)sivo; Zoneamento bioclimatológico utilizando o índice de temperatura e umidade, para bovinocultura de leite na Região Sudeste do Brasil; Publicações geradas pelo Núcleo Temático; Núcleo Temático Qualidade do Leite e Segurança Alimentar -Projetos: Diagnóstico e gestão da qualidade na produção de leite; Patogenia, imunologia e controle de Babesia bovis, Babesia bigemina, Anaplasma marginale e seus vetores; Publicações geradas pelo Núcleo Temático; Núcleo Temático Sócio-economia do Agronegócio do Leite Projetos: Análise da dinâmica do setor leiteiro; Estudo econômico da tecnologia de pastejo rotativo na produção de leite; Publicações geradas pelo Núcleo Temático; Subprojetos em fase inicial de execução; Transferência de tecnologia -Comunicação empresarial Negócios Tecnológicos Informaçãor Projeto: Ações para transferência de conhecimento e tecnologia na Embrapa Gado de Leite; Perfil da Embrapa Gado de Leite; Infra-estrutura; Recursos humanos; Acordos e convênios de cooperação técnica e financeira.bitstream/item/81938/1/Relatorio-tecnico-Embrapa-gado-de-leite.pd

    Proton-neutron self-consistent quasiparticle random phase approximation within the o(5) model

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    15 págs.; 7 figs.; 1 tab.; 1 app. ; PACS number(s): 21.60.Jz, 23.40.Hc, 23.90.1wThe self-consistent quasiparticle random phase approximation (SCQRPA) within the O(5) model in the coupled proton-neutron representation is analyzed. The exact vacuum wave function is used to compute all involved matrix elements. A stability analysis of the stationary points is performed. A phase transition from the uncoupled to the coupled stable proton-neutron regime beyond the QRPA breakdown value of the particle-particle strength is evidenced. The excitation energies are close to the lowest stable exact eigenvalues given by the diagonalization procedure for all cases. The conditions for which the Ikeda sum rule is fulfilled for all values of the particle-particle strength are pointed out. ©2000 American Physical SocietyOne of us (D.S.D.) is grateful for the financial support given by CNRS during his stay in Grenoble, where the work was performed.Peer Reviewe

    Modulation of infusion processes to obtain coffee-derived food ingredients with distinct composition

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    Coffee infusion experiments were conducted to infer how operational variables (time, temperature, mass to volume ratio, and grinding) might affect the efficiency and/or selectivity of compounds extraction. Although the different variables have extensively been reported independently, to the best of our knowledge, no experimental design was yet delineated to study the simultaneous effect of variables in coffee composition. This study fulfills this gap by constructing surface models that reflect the responses in a wide-ranging design space. The freeze-dried extracts were compared regarding the overall yield of extraction, carbohydrate content and composition, caffeine, chlorogenic acid (5-CQA) content, color, and viscosity. Temperature was the major factor for coffee extracts differentiation, regarding both overall and carbohydrates yield and composition. The extraction process efficiency is more related to galactomannans extraction than arabinogalactans. Varying operational conditions, coffee extracts with distinct chemical properties are obtained from the same roasted coffee, broadening their applications in food formulations.Thanks are due to the University of Aveiro and FCT/MCT for the financial support for the QOPNA research Unit (FCT UID/QUI/00062/2019) through national founds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement, and to the Portuguese NMR Network. Guido R. Lopes and Cláudia P. Passos were supported by individual doc (SFRH/BD/104855/2014) and post-doc (SFRH/BDP/107881/2015) grants by FCT, respectiveinfo:eu-repo/semantics/publishedVersio
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