5,482 research outputs found

    A note on the phase transition in a topologically massive Ginzburg-Landau theory

    Full text link
    We consider the phase transition in a model which consists of a Ginzburg-Landau free energy for superconductors including a Chern-Simons term. The mean field theory of Halperin, Lubensky and Ma [Phys. Rev. Lett. 32, 292 (1974)] is applied for this model. It is found that the topological mass, θ\theta, drives the system into different regimes of phase transition. For instance, there is a θc\theta_{c} such that for θ<θc\theta<\theta_{c} a fluctuation induced first order phase transition occurs. On the other hand, for θ>θc\theta>\theta_{c} only the second order phase transition exists. The 1-loop renormalization group analysis gives further insight to this picture. The fixed point structure exhibits tricritical and second order fixed points.Comment: Revised version; uses a more physical parametrization of the renormalization group equations; new references added; one figure added; EuroLatex, 6 page

    A non-perturbative approach to the Coleman- Weinberg mechanism in massless scalar QED

    Get PDF
    We rederive non-perturbatively the Coleman-Weinberg expression for the effective potential for massless scalar QED. Our result is not restricted to small values of the coupling constants. This shows that the Coleman- Weinberg result can be established beyond the range of validity of perturbation theory. Also, we derive it in a manifestly renormalization group invariant way. It is shown that with the derivation given no Landau ghost singularity arises. The finite temperature case is discussed. Pacs number: 11.10.Ef,11.10.Gh

    Towards a knowledge-based system to assist the Brazilian data-collecting system operation

    Get PDF
    A study is reported which was carried out to show how a knowledge-based approach would lead to a flexible tool to assist the operation task in a satellite-based environmental data collection system. Some characteristics of a hypothesized system comprised of a satellite and a network of Interrogable Data Collecting Platforms (IDCPs) are pointed out. The Knowledge-Based Planning Assistant System (KBPAS) and some aspects about how knowledge is organized in the IDCP's domain are briefly described

    Comportamento de híbridos de coqueiro nos Tabuleiros Costeiros do Piauí.

    Get PDF
    Com o objetivo de avaliar o comportamento de híbridos de coqueiro nas condições de clima e solo dos Tabuleiros Costeiros do Piauí, conduziu-se um experimento no Campo Experimental da Embrapa Meio-Norte em Parnaíba-PI, no período de 2002 a 2004. Utilizou-se o delineamento experimental de blocos ao acaso, com sete tratamentos e quatro repetições. Os tratamentos foram constituídos por cinco híbridos entre coqueiro-anão e coqueiro-gigante: AAG x GBrPF, AVG x GBrPF, AVeJ x GBrRN, AAG x GOA e AVG x GOA) e os dois parentais (GBrRN e AVeJ) como testemunha. As características vegetativas, avaliadas semestralmente, foram o número de folhas vivas (NFV) emitidas (NFE), e as reprodutivas, avaliadas mensalmente, foram o número de inflorescências emitidas (NIE), número de flores femininas por inflorescência (NFFI) e número de frutos colhidos/planta (NFC). Os híbridos AAG x GBrPF; AVG x GBrP e AVG x GOA apresentam maior potencial de adaptação às condições edafoclimáticas dos Tabuleiros Costeiros do Piauí.bitstream/item/35881/1/BP61.pd

    Comportamento de cultivares de coqueiro-anão nos Tabuleiros Costeiros do Piauí.

    Get PDF
    bitstream/CPAMN-2009-09/20331/1/BOLP60.pd

    Debulhador de feijão-verde: manual de uso.

    Get PDF
    Este documento destina-se a orientar, de forma adequada, a utilização do debulhador de feijão-verde desenvolvido pela Embrapa Meio-Norte. Esse debulhador elétrico proporcionará rapidez e eficiência nos trabalhos, com economia e total segurança.bitstream/item/184221/1/Manual.pd

    Microbiological quality of Portuguese yogurts

    Get PDF
    The microbiological quality of four brands of natural yogurts and two probiotic yogurts available in the Portuguese market, was evaluated during the shelf-life period. Although the specific flora decreased during storage it was always within the range of recommended values. No coliforms and an insignificant number of fungi were detected
    corecore