660 research outputs found
OS ESLAVOS NUM CLÁSSICO PORTUGUÊS DO SÉCULO XVII
OS ESLAVOS NUM CLÁSSICO PORTUGUÊSDO SÉCULO XVII(Considerações sôbre o que deles dizFr. Manoel dos Anjos na sua "História Universal"
A CRONOLOGIA DOS EMPRÉSTIMOS
A CRONOLOGIA DOS EMPRÉSTIMO
NOVAS NOTAS AO «GLOSSÁRIO LUSO ASIÀTICO»
NOVAS NOTAS AO «GLOSSÁRIOLUSO ASIÀTICO
Critical behavior of hard-core lattice gases: Wang-Landau sampling with adaptive windows
Critical properties of lattice gases with nearest-neighbor exclusion are
investigated via the adaptive-window Wang-Landau algorithm on the square and
simple cubic lattices, for which the model is known to exhibit an Ising-like
phase transition. We study the particle density, order parameter,
compressibility, Binder cumulant and susceptibility. Our results show that it
is possible to estimate critical exponents using Wang-Landau sampling with
adaptive windows. Finite-size-scaling analysis leads to results in fair
agreement with exact values (in two dimensions) and numerical estimates (in
three dimensions).Comment: 20 pages, 11 figure
Cosmological models with linearly varying deceleration parameter
We propose a new law for the deceleration parameter that varies linearly with
time and covers Berman's law where it is constant. Our law not only allows one
to generalize many exact solutions that were obtained assuming constant
deceleration parameter, but also gives a better fit with data (from SNIa, BAO
and CMB), particularly concerning the late time behavior of the universe.
According to our law only the spatially closed and flat universes are allowed;
in both cases the cosmological fluid we obtain exhibits quintom like behavior
and the universe ends with a big-rip. This is a result consistent with recent
cosmological observations.Comment: 12 pages, 7 figures; some typo corrections; to appear in
International Journal of Theoretical Physic
Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water
The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 mu L L-1) and essential oil of Lippia alba (EOL) (10 or 20 mu L L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 mu L L-1) and EOL (10 or 20 mu L L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 mu L L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS/PRONEX) [10/0016-8]; Conselho Nacional de Pesquisa e Desenvolvimento Cientifico (CNPq) [470964/2009-0]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPqinfo:eu-repo/semantics/publishedVersio
Two-dimensional lattice polymers: adaptive windows simulations
We report a numerical study of self-avoiding polymers on the square lattice,
including an attractive potential between nonconsecutive monomers. Using
Wang-Landau sampling (WLS) with adaptive windows, we obtain the density of
states for chains of up to N=300 monomers and associated thermodynamic
quantities. The method enables one to simulate accurately the low-temperature
regime, which is virtually inaccessible using traditional methods. Instead of
defining fixed energy windows, as in usual WLS, this method uses windows with
boundaries that depend on the set of energy values on which the histogram is
flat at a given stage of the simulation. Shifting the windows each time the
modification factor is reduced, we eliminate border effects that arise in
simulations using fixed windows.Comment: 8 pages, 5 figure
Frictional drag between non-equilibrium charged gases
The frictional drag force between separated but coupled two-dimensional
electron gases of different temperatures is studied using the non-equilibrium
Green function method based on the separation of center-of-mass and relative
dynamics of electrons. As the mechanisms of producing the frictional force we
include the direct Coulomb interaction, the interaction mediated via virtual
and real TA and LA phonons, optic phonons, plasmons, and TA and LA
phonon-electron collective modes. We found that, when the distance between the
two electron gases is large, and at intermediate temperature where plasmons and
collective modes play the most important role in the frictional drag, the
possibility of having a temperature difference between two subsystems modifies
greatly the transresistivity.Comment: 8figure
Characterization and basic guidelines for the quality control of chitosan for drug delivery in pharmaceutical applications
Chitosan is increasingly used as an alternative to synthetic polymers due to its water solubility, biodegradability, and biological activity. In this work, chitosan samples from three suppliers were evaluated and characterized by physicochemical methods in an attempt to analyze pharmaceutical applications. The degree of deacetylation (DD) was determined by 1H NMR, IR spectra, potentiometric titration, and UV spectrophotometry. The analysis was supplemented by the techniques of DSC, TG, loss on drying, pH of the suspension, heavy metals, sulphated ash, and triple detector size exclusion chromatography (TriSEC). The use of UV, IR, and 1H NMR techniques to determine the degree of deacetylation, limit testing for heavy metals and sulphated ash to analyze inorganic waste, and TriSEC to analyze molecular weights and molecular distribution are recommended as basic requirements for pharmaceutical applications.Colegio de Farmacéuticos de la Provincia de Buenos Aire
- …