822 research outputs found
Two-flavor condensates in chiral dynamics: temperature and isospin density effects
Isospin density and thermal corrections for several condensates are
discussed, at the one-loop level, in the frame of chiral dynamics with pionic
degrees of freedom. The evolution of such objects give an additional insight
into the condensed-pion phase transition, that occurs basically when
|\mui|>m_\pi, being |\mui| the isospin chemical potential. Calculations are
done in both phases, showing a good agreement with lattice results for such
condensates.Comment: 9 pages, 10 figure
Weinberg power counting and the quark determinant at small chemical potential
We construct an effective action for QCD by expanding the quark determinant
in powers of the chemical potential at finite temperature in the case of
massless quarks. To cut the infinite series we adopt the Weinberg power
counting criteria. We compute the minimal effective action (~p^4), expanding in
the external momentum, which implies the use of the hard thermal loop
approximation. Our main result is a gauge invariant expression for the phase
theta of the functional determinant in QCD, and recovers dimensional reduction
in the high-temperature limit. We compute, analytically, in the range
of p << 2 pi T, including perturbative and nonperturbative contributions, the
latter treated within the mean field approximation. Implications for lattice
simulations are briefly discussed.Comment: 5 pages, 2 figures. v2: title changed, expanded discussion and added
example (calculation of at high temperature). Published in PR
Caracterización morfológica, fisiológica y patogénica de moniliophthora roreri aislados de cinco provincias de la costa ecuatoriana
The moniliasis of cacao, caused by the fungus Moniliophthora roreri, is the main problem, so is necessary to deepen the knowledge of the agent and the differences between populations of the fungus from various sources. To achieve the objectives of this research was carried out on samples collected in ten cocoa production farms located in five provinces of the Coast, was carried isolates that were evaluated and identified by morphological criteria (diameter, edge, color and texture of colonies; type and size of conidia, etc.), physiological (development at a given temperature, weight of mycelium) and pathogenic (time of onset and severity of symptoms), in order to initiate the characterization of populations of the fungus in the country and have a bank of isolates for further investigation at different levels. We used culture media and liquid to assess the morphological and physiological characteristics of 50 isolates. The pathogenicity was evaluated by inoculating healthy fruit with dry conidia method over a period of fourteen days. No morphological differences were found on the edge and texture of the colonies among isolates studied, but variations in color, with shades of white, cream, light brown to dark brown. Also the size and shape of conidia differences, distinguishing conidia globose, subglobose, elliptical. There were variations in the growth of the colonies and the weight of mycelium in different isolates, regardless of their origin, with the exception of 80% of those from areas of the province of Los Rios, who had a higher growth rate on solid medium
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