24,249 research outputs found

    Quantum statistical correlations in thermal field theories: boundary effective theory

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    We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field ϕc\phi_c, and if we trade free propagators at zero temperature for their finite-temperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schr\"{o}dinger field-representation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle-point for fixed boundary fields, which is the classical field ϕc\phi_c, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally-reduced effective theory for the thermal system. We calculate the two-point correlation as an example.Comment: 13 pages, 1 figur

    Teratoma Sacrococcígeo:Caso Clínico

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    O teratoma sacrococcígeo, embora raro, é a neoplasia mais frequentemente diagnosticada no período neonatal. O diagnóstico é geralmente estabelecido após o nascimento, apesar do uso da ultrassonografia obstétrica permitir um número crescente de sinalizações pré -natais. O principal diagnóstico diferencial é o mielomeningocelo. A monitorização de marcadores tumorais sugestivos da presença de células malignas de um tumor do saco vitelino associado, tal como a alfa- -fetoproteína, e a ressecção precoce do tumor são recomendáveis. Apresenta -se o caso clínico de um recém -nascido do sexo feminino a quem foi detectado ao nascimento uma massa sacrococcígea. A ressonância magnética nuclear admitiu tratar -se de um teratoma sacrococcígeo e o valor de alfa -fetoproteína era normal para a idade da doente. Foi realizada ressecção total do tumor com remoção do cóccix e confi rmado o diagnóstico em estudo anátomo -patológico. A reavaliação posterior da criança revelou um valor decrescente da alfa -fetoproteína, ausência de défi ces motores e um bom aspecto cosmético. A apresentação deste caso clínico pretende realçar a importância do diagnóstico precoce, fundamental para a abordagem terapêutica adequada e melhor prognóstico

    Teste de tetrazólio em trigo: vigor e classes de sementes.

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    Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013

    Improving the Knowledge on Seismogenic Sources in the Lower Tagus Valley for Seismic Hazard Purposes

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    The Lower Tagus Valley, that includes the metropolitan area of Lisbon, has been struck by several earthquakes which produced significant material damage and loss of lives. Their exact location remains unknown. Our goal is to shed some light into the seismogenic sources in the area using seismic reflection and geological data. In areas with no seismic coverage, potential-field data interpretation was carried out. Seismicity was overlaid to the potential seismogenic structures and high-resolution data was acquired in order to confirm which structures have been active into the Quaternary. Three major fault-zones affecting the Neogene were identified: V. F. Xira, Samora-Alcochete and Pinhal Novo. For the first fault, strong evidences suggest it is active. The other two fault-zones and other structures previously unknown can be correlated with several epicentres. Empirical relationships between maximum moment magnitude and fault area indicate that MW > 6.5 earthquakes can be expected for the larger structures

    Adequação de metodologia para avaliação da viabilidade de sementes de trigo pelo teste de tetrazólio.

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    Edição Especial contendo os Anais do XVIII Congresso Brasileiro de Sementes, Florianópolis, set. 2013

    Insights about destination brand: Madeira case study

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    The concept of brand as known today is passed through various (re) definitions over the years. Initially, the brand was associated with house products, but with the evolution of society has come to represent industrial products, people, values, and services. Nowadays due to the great offer of tourist destinations, brands also represent countries, cities, and regions. This type of brands, result from maturation and of the coverage of the functionality of the same. Thus, the tourist brands or place brands, come from the necessity to value the places through its unique characteristics, boosting the visit of tourists and the sustainability of the destination. The island of Madeira is a typical tourist destination, which stands out from the competition through its heritage, in terms of culture and patrimony. With its economy based on tourism and to measure the importance of the Brand, an interview was conducted at one of the main actors in this area, specifically the Regional Tourism Director of the Autonomous Region of Madeira. In addition we have interview 118 tourists during July and August 2017 at Madeira airport.info:eu-repo/semantics/publishedVersio

    Constraint on the chemical potentials of hydrogen and proton in recombination

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    In this paper, we revisit the hydrogen recombination history from a novel perspective: the evolution of chemical potentials. We derive expressions for the chemical potentials, which depend on the thermal bath temperature and the ionization degree of the universe. Our main finding reveals a constraint between the chemical potentials of hydrogen and proton at z1200z\approx 1200 when the free electron fraction is Xe1/3X_e\approx 1/3. Furthermore, we present important data on the chemical potentials during recombination, highlighting the differences between the predictions of the Peebles' and CosmoRec code solutions. Finally, we discuss a particular case related to the chemical potential of hydrogen.Comment: 5 pages, 3 figure
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