1,358 research outputs found

    Thermal equilibrium states in perturbative Algebraic Quantum Field Theory in relation to Thermal Field Theory

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    In the first part, we analyse the properties of an interacting, massive scalar field in an equilibrium state over Minkowski spacetime. We compare the known real- and imaginary-time formalisms of Thermal Field Theory with the recent construction by Fredenhagen and Lindner of a KMS state for perturbative interacting theories in the context of perturbative Algebraic Quantum Field Theory, in the adiabatic limit. In particular, we show that the construction of Fredenhagen and Lindner reduces to the real-time formalism only if the cocycle which intertwines between the free and interacting dynamics can be neglected. Furthermore, the Fredenhagen and Lindner construction reduces to the ordinary imaginary-time formalism if one considers the expectation value of translation invariant observables. We thus conclude that a complete description of thermal equilibrium for interacting scalar fields is generally obtained only by means of the state constructed by Fredenhagen and Lindner, which combines both formalisms of Thermal Field Theory. We also discuss the properties of the expansion of the Fredenhagen and Lindner construction in terms of Feynman diagrams in the adiabatic limit. We finally provide examples showing that the real- and the imaginary-time formalisms fail to describe thermal equilibrium already at first or second order in perturbation theory. The results presented in this part are summarized in (BDP19). In the second part, we discuss the so-called secular effects, characterized by the appearance of polynomial divergences in the large time limit of truncated perturbative expansions of expectation values in Quantum Field Theory. We show that, although such effect is an artifact of perturbation theory, and thus may not be obtained via exactly solving the dynamical equation if possible, they do not represent the breakdown of perturbation theory itself. Instead, we show that the polynomial divergences follow from a bad choice of state, and we present examples of states which produce expectation values whose perturbative expansion does not present secular effects. In particular, we point that it is possible to obtain non time-divergent perturbative expressions from thermal equilibrium states for the interacting theory. This last part is based on a research project which, by the time this thesis was written, had not been concluded yet

    Absorption and fluorescence properties of chromophoric dissolved organic matter of the eastern Bering Sea in the summer with special reference to the influence of a cold pool

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    The absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) are reported for the inner shelf, slope waters and outer shelf regions of the eastern Bering Sea during the summer of 2008, when a warm, thermally stratified surface mixed layer lay over a cold pool (< 2 °C) that occupied the entire middle shelf. CDOM absorption at 355 nm (<i>a</i><sub>g</sub>355) and its spectral slope (<i>S</i>) in conjunction with excitation–emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC) revealed large variability in the characteristics of CDOM in different regions of the Bering Sea. PARAFAC analysis aided in the identification of three humic-like (components one, two and five) and two protein-like (a tyrosine-like component three, and a tryptophan-like component four) components. In the extensive shelf region, average absorption coefficients at 355 nm (<i>a</i><sub>g</sub>355, m<sup>−1</sup>) and DOC concentrations (μM) were highest in the inner shelf (0.342 ± 0.11 m<sup>−1</sup>, 92.67 ± 14.60 μM) and lower in the middle (0.226 ± 0.05 m<sup>−1</sup>, 78.38 ± 10.64 μM) and outer (0.185 ± 0.05 m<sup>−1</sup>, 79.24 ± 18.01 μM) shelves, respectively. DOC concentrations, however were not significantly different, suggesting CDOM sources and sinks to be uncoupled from DOC. Mean spectral slopes <i>S</i> were elevated in the middle shelf (24.38 ± 2.25 μm<sup>−1</sup>) especially in the surface waters (26.87 ± 2.39 μm<sup>−1</sup>) indicating high rates of photodegradation in the highly stratified surface mixed layer, which intensified northwards in the northern middle shelf likely contributing to greater light penetration and to phytoplankton blooms at deeper depths. The fluorescent humic-like components one, two, and five were most elevated in the inner shelf most likely from riverine inputs. Along the productive "green belt" in the outer shelf/slope region, absorption and fluorescence properties indicated the presence of fresh and degraded autochthonous DOM. Near the Unimak Pass region of the Aleutian Islands, low DOC and <i>a</i><sub>g</sub>355 (mean 66.99 ± 7.94 μM; 0.182 ± 0.05 m<sup>−1</sup>) and a high <i>S</i> (mean 25.95 ± 1.58 μm<sup>−1</sup>) suggested substantial photobleaching of the Alaska Coastal Water, but high intensities of humic-like and protein-like fluorescence suggested sources of fluorescent DOM from coastal runoff and glacier meltwaters during the summer. The spectral slope <i>S</i> vs. <i>a</i><sub>g</sub>355 relationship revealed terrestrial and oceanic end members along with intermediate water masses that were modeled using nonlinear regression equations that could allow water mass differentiation based on CDOM optical properties. Spectral slope <i>S</i> was negatively correlated (<i>r</i><sup>2</sup> = 0.79) with apparent oxygen utilization (AOU) for waters extending from the middle shelf into the deep Bering Sea indicating increasing microbial alteration of CDOM with depth. Although our data show that the CDOM photochemical environment of the Bering Sea is complex, our current information on its optical properties will aid in better understanding of the biogeochemical role of CDOM in carbon budgets in relation to the annual sea ice and phytoplankton dynamics, and to improved algorithms of ocean color remote sensing for this region

    Seleção de linhagens de feijão-caupi para o cerrado do Amapá.

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    O cerrado do Amapá possui amplas características para a produção de alimentos, sendo o feijão-caupi uma grande opção. Assim, selecionar cultivares para utilização no processo mecanizado deve ser uma meta a ser seguida, sendo este o objetivo do experimento

    Genótipos prostrados de feijão-caupi no Cerrado do Amapá.

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    O cerrado do Estado do Amapá apresenta totais condições para a produção de grãos, sendo o feijão-caupi uma das opções mais viáveis. Assim, selecionar cultivares para este ambiente deve ser uma das metas da pesquisa. No caso em estudo, o experimento objetivou avaliar linhagens de porte prostrado e semi-prostrado. Em Latossolo Amarelo, clima do tipo Ami, usou-se o delineamento experimental de blocos ao acaso e quatro repetições, adubação de 80 kg ha-1 (superfosfato triplo) e 50 kg ha-1 (cloreto de potássio). A semeadura manual ocorreu em fileiras espaçadas de 0,80 m, com área útil de 8 m2 e população de 100 mil plantas ha-1. A análise de variância mostrou diferença significativa pelo teste de Tukey (p< 0,05). O melhor desempenho produtivo de 1.216,7 kg ha-1 foi da linhagem MNC02-676F-1, que apresenta grão da subclasse mulato, seguida pela cultivar BRS-Pajeú com 1.119,0 kg ha-1, com grão da subclasse sempre verde. A linhagem BRS Juruá alcançou menor período de floração, enquanto o maior comprimento de vagem foi do genótipo MNC02-677F-2. Todas as linhagens mostraram tolerância à incidência de doenças.Disponível em: http://www.conac2012.org/resumos/pdf/133c.pdf. Acesso em: 22 jul. 2013

    Follow-up of bone lesions in an experimental multiple myeloma mouse model: description of an in vivo technique using radiography dedicated for mammography.

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    The evolution of bone lesions in transplantable C57BL/KaLwRjj 5T mouse myeloma (MM) has been followed in vivo. Mice were anaesthetised and a radiograph of the pelvis and hind legs was performed by a radiograph dedicated for mammography. This is the first description of an in vivo technique under experimental conditions whereby the development of bone lesions owing to the MM growth was demonstrated

    Mass production of Bacillus subtilis and Trichoderma viride for the control of Phyllosticta citricarpa (Teleomorph: Guignardia citricarpa).

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    The work was aimed at studying the production of cells and metabolites of Bacilius subtilis (ACB-69) and of Trichoderma viride conidia (ACB-14) on different substrates, since they can potentially control Phyllosticta citricarpa. Our results showed that the medium consisting of cotton meal added of hydrolized protein provided the highest yield of B. subtiiis cells (2.44 x IO9 cells/mL), after the culture had been incubated for three days. This liquid substrate also provided conditions for the bacterium to produce thermostable metabolites, in sufficient amounts to inhibit the plant pathogen's micelial growth. The production of B. subtilis under the solid fermentation system performed better on the brewers rice substrate; the number of bactéria; cells decreased as the substrate concentration increased. In general, the liquid medium yielded a higher amount of B. subtilis than the solid medium. With regard to the large scale production of T. viride, it was verified that the substrates tested had a low spore production; the best substrate among those tested (com cob + hydrolized protein) only yielded 2.17 x IO6 conidia/mL. O objetivo foi estudar a produção de células e de metabólitos de Bacillus subtilis (ACB-69) e de conídios de Trichoderma viride (ACB-14) em diferentes substratos, pois apresentam potencial para o controle de Phyllosticta citricarpa. O meio constituído de farelo de algodão acrescido de proteína hidrolisada foi o que proporcionou maior produção de células de B. subtilis (2,4 x 109 células/mL), após três dias de incubação da cultura. Esse substrato líquido também propiciou condições para que a bactéria produzisse metabólitos termoestáveis e, em quantidades suficientes para inibir o crescimento micelial do fitopatógeno. A produção de B. subtilis pelo sistema de fermentação sólida foi melhor no substrato quirera de arroz sendo que o número de células da bactéria diminuiu à medida que aumentou a concentração do substrato. De um modo geral, o meio líquido foi superior ao sólido para a produção de B. subtilis. Com relação à produção de T. viride, verificou-se que os substratos testados apresentaram baixa produção de esporos, sendo que o melhor substrato testado (sabugo de milho + proteína hidrolisada) produziu apenas 2,2 x 106 conídios/mL

    Museus e comunicação pública : um estudo sobre os Tribunais Superiores no Brasil

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    Dissertação (mestrado)—Universidade de Brasília, Instituto de Expressão e Comunicação, Departamento de Comunicação, 2019.A presente dissertação se refere aos museus localizados nos cinco Tribunais Superiores do Judiciário no Brasil. São eles: Supremo Tribunal Federal, Superior Tribunal de Justiça, Superior Tribunal Militar, Tribunal Superior Eleitoral e Tribunal Superior do Trabalho. O objetivo da pesquisa foi compreender se os museus mencionados constituem-se como iniciativas de Comunicação Pública e de promoção do direito à informação. A problemática gira em torno do distanciamento entre os museus e a população, que foi constatado em pesquisa do Instituto Brasileiro de Museus (2012) e pôde também ser confirmado pelo baixo quantitativo de público informado pelos gestores dos museus estudados. A escolha pelo estudo dessas instituições se justifica porque museus desta tipologia, considerados institucionais, constituem mais de 50% do cenário museológico da capital federal. Investigar a dinâmica de divulgação e acesso a esses espaços públicos é uma necessidade a ser atendida. Para tanto, foi utilizado o referencial metodológico denominado Hermenêutica de Profundidade, de John B. Thompson (1995), cruzando interpretação documental, bibliográfica, entrevistas semiestruturadas e reinterpretação de dados. Foi possível constatar que os museus analisados não foram majoritariamente criados como resultado de uma estratégia de comunicação com o público externo, mas sim para atender a demandas institucionais. Nesse sentido, pela ótica teórica e normativa da Museologia e da Comunicação, foi possível concluir que os museus estudados apresentam dificuldades no cumprimento da função social que seria típica à sua natureza.This dissertation refers to the museums located in the five Superior Courts of the Judiciary in Brazil. They are: Supremo Tribunal Federal, Superior Tribunal de Justiça, Superior Tribunal Militar, Tribunal Superior Eleitoral e Tribunal Superior do Trabalho. Research‘s objective was to understand if the mentioned museums constitute as initiatives of Public Communication and promotion of the right to information. The problematic revolves around the distance between those museums and population, which was verified in a research developed by the Brazilian Institute of Museums (2012) and could be also confirmed by the low amount of public informed by the managers of those studied museums. The choice for studying of these institutions is justified by the fact that museums of this type, considered institutional, constitute more than 50% of the museological scene of the federal capital. Investigating the dynamics of disclosure and access to these public spaces is a need to be faced. For that, the methodological reference called Depth Hermeneutics, by John B. Thompson (1995), was used, crossing documentary, bibliographic interpretation, semi-structured interviews and reinterpretation of data. Following this way it was possible to verify that the analysed museums were not for the most part created as a result of a strategy of communication to the external public, but to face institutional demands. In a accordance to these permises, from the theoretical and normative point of view of Museology and Communication, it was possible to conclude that the museums studied presented difficulties in fulfilling the social function that would be typical of their nature
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