720 research outputs found
Finite-size effects on the chiral phase diagram of four-fermion models in four dimensions
We study the size dependence of the dynamical symmetry breaking in the
four-dimensional Nambu-Jona-Lasinio model. We show that the presence of
boundaries reduces the chiral breaking region, and this effect is strengthened
for a larger number of compactified dimensions. A critical value for the length
of the compactified dimensions exists, below which the dynamical symmetry
breaking is not possible. Considering finite temperature and chemical
potential, the chiral phase structure for the system with compactified
dimensions is obtained. A gradual decreasing of the chiral breaking region with
increasing of chemical potential is found. Also, at fixed chemical potential,
the decreasing of the size of the system changes the order of the chiral phase
transition.Comment: LATEX 14 pages 2 figure
Halperin-Lubensky-Ma effect in type-I superconducting films
In this note we employ concurrently techniques of generalized
-functions and compactification methods introduced in previous
publications, to study the Halperin-Lubensky-Ma theory of induced weak
first-order phase transitions applied to type-I superconducting films. We
obtain closed formulas to the critical temperature and to the size temperature
as functions of the film thickness.Comment: 4 pages, RevTex
Evaluation of alternative postharvest treatments (water heat treatment, ultrasounds, thermosonication and UV-C radiation) to improve safety and quality of whole tomato
Modelling the kinetics of peroxidase inactivation, colour and texture changes of pumpkin (Cucurbita maxima L.) during blanching
The effects of blanching treatment on peroxidase inactivation, colour and texture of pumpkin (Cucurbita maxima L.) were studied in the temperature range of 75–95 C.
Peroxidase inactivation followed a first-order Arrhenius model, where the activation energy and rate of the reaction at a reference temperature of 85 C were 86.20 ± 5.57 kJ mol 1 and 0.27 ± 0.01 min 1, respectively. During blanching, pumpkin became darker and softer with processing time. The degradation of colour (evaluated throughout CIE L*a*b* colour system, with chroma index and total colour difference) and texture parameters (firmness and energy) showed a fractional conversion model kinetics, being the temperature effect on kinetic parameters well described by the Arrhenius law. The results of this work are a good tool to further optimise pumpkin blanching conditions
New Records Of Bird Species From Ilha Grande, State Of Rio De Janeiro, Southeastern Brazil
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We add 32 new records of species to the existing checklist of birds of the coastal island of Ilha Grande, state of Rio de Janeiro, Brazil. Notably, seven of these species are endemic to the Atlantic Forest. Sporophila falcirostris is globally Vulnerable and Haematopus palliatus is Near Threatened in Brazil. We also report the second record of Agelaioides badius from Rio de Janeiro state. We also compare our species list with lists of birds of Ilhabela and Anchieta islands. While some of the newly recorded species are probably non-resident to Ilha Grande or represent range expansions, most species occur in Rio de Janeiro throughout the year. Thus, our records may be a consequence of the surveying new sites on the island but also recent colonization. Our study increases the number of bird species known to occur on Ilha Grande from 222 to 254, which is one-third of the species reported from Rio de Janeiro state. We recorded 13 species threatened by extinction at regional, national or global levels. © 2016 Check List and Authors.126CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico305798/2014-6, FAPERJ, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de JaneiroE-26/102.837868/2012, FAPERJ, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de JaneiroUERJ, Universidade do Estado do Rio de JaneiroConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Novel antimicrobial secondary metabolites from a Penicillium sp. isolated from Brazilian cerrado soil
The morphological features of a Penicillium , isolated from Brazilian
cerrado soil, were characterized and showed to be distinctly different
from all well-defined Penicillium species. Chemical and biological
investigation on the ethyl acetate extract of this Penicillium isolate
resulted in the isolation of three new naphthalenoids: a major
metabolite, methyl
6-acetyl-4-methoxy-5,7,8-trihydroxynaphthalene-2-carboxylate and two
minor ones, methyl
6-acetyl-4-methoxy-7,8-dihydroxynaphthalene-2-carboxylate and methyl
6-acetyl-4-methoxy-5,8-dihydroxynaphthalene-2-carboxylate. Their
structures were determined based on their mono and bidimensional
nuclear magnetic resonance data. Acetyl, allyl and methoxyl derivatives
of the major metabolite were prepared in order to establish
structure-activity relation. Antimicrobial activity of the major
natural product and its semi-synthetic derivatives was screened by
macro dilution methodology and the corresponding minimum inhibitory
concentrations were determined. Natural secondary metabolite methyl
6-acetyl-4-methoxy-5,7,8-trihydroxynaphthalene-2-carboxylate, isolated
in a very high yield (0.3175 mg.L-1) showed to be the most active
compound, possessing expressive activity against Candida albicans
(minimum inhibitory concentration (MIC) 32 \ub5g/mL), Listeria
monocitogenes and Bacillus cereus (MIC 64 \ub5g/mL for both)
Avaliação e otimização da termossonicação como tratamento alternativo de pós-colheita de tomate fresco (Lycopersicum esculentum, cv. Zinac)
info:eu-repo/semantics/publishedVersio
Charged particle production in the Pb+Pb system at 158 GeV/c per nucleon
Charged particle multiplicities from high multiplicity central interactions
of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured in the
central and far forward projectile spectator regions using emulsion chambers.
Multiplicities are significantly lower than predicted by Monte Carlo
simulations. We examine the shape of the pseudorapidity distribution and its
dependence on centrality in detail.Comment: 17 pages text plus 12 figures in postscript 12/23/99 -- Add TeX
version of sourc
Primordial Nucleosynthesis Constraints on Z' Properties
In models involving new TeV-scale Z' gauge bosons, the new U(1)' symmetry
often prevents the generation of Majorana masses needed for a conventional
neutrino seesaw, leading to three superweakly interacting ``right-handed''
neutrinos nu_R, the Dirac partners of the ordinary neutrinos. These can be
produced prior to big bang nucleosynthesis by the Z' interactions, leading to a
faster expansion rate and too much ^4He. We quantify the constraints on the Z'
properties from nucleosynthesis for Z' couplings motivated by a class of E_6
models parametrized by an angle theta_E6. The rate for the annihilation of
three approximately massless right-handed neutrinos into other particle pairs
through the Z' channel is calculated. The decoupling temperature, which is
higher than that of ordinary left-handed neutrinos due to the large Z' mass, is
evaluated, and the equivalent number of new doublet neutrinos Delta N_nu is
obtained numerically as a function of the Z' mass and couplings for a variety
of assumptions concerning the Z-Z' mixing angle and the quark-hadron transition
temperature T_c. Except near the values of theta_E6 for which the Z' decouples
from the right-handed neutrinos, the Z' mass and mixing constraints from
nucleosynthesis are much more stringent than the existing laboratory limits
from searches for direct production or from precision electroweak data, and are
comparable to the ranges that may ultimately be probed at proposed colliders.
For the case T_c = 150 MeV with the theoretically favored range of Z-Z'
mixings, Delta N_nu 4.3 TeV for any value of theta_E6. Larger
mixing or larger T_c often lead to unacceptably large Delta N_nu except near
the nu_R decoupling limit.Comment: 22 pages, 5 figures; two additional references adde
On the linear forms of the Schrodinger equation
Generalizing the linearisation procedure used by Dirac and later by
L\'evy-Leblond, we derive the first-order non-relativistic wave equations for
particles of spin 1 and spin 3/2 starting from the Schrodinger equation
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