Quantum vortex reconnections

We study reconnections of quantum vortices by numerically solving the governing Gross-Pitaevskii equation. We find that the minimum distance between vortices scales differently with time before and after the vortex reconnection. We also compute vortex reconnections using the Biot-Savart law for vortex filaments of infinitesimal thickness, and find that, in this model, reconnection are time-symmetric. We argue that the likely cause of the difference between the Gross-Pitaevskii model and the Biot-Savart model is the intense rarefaction wave which is radiated away from a Gross-Pitaeveskii reconnection. Finally we compare our results to experimental observations in superfluid helium, and discuss the different length scales probed by the two models and by experiments.Comment: 23 Pages, 12 Figure

High-order time-splitting Hermite and Fourier spectral methods

In this paper, we are concerned with the numerical solution of the time-dependent Gross-Pitaevskii Equation (GPE) involving a quasi-harmonic potential. Primarily, we consider discretisations that are based on spectral methods in space and higher-order exponential operator splitting methods in time. The resulting methods are favourable in view of accuracy and efficiency; moreover, geometric properties of the equation such as particle number and energy conservation are well captured. Regarding the spatial discretisation of the GPE, we consider two approaches. In the unbounded domain, we employ a spectral decomposition of the solution into Hermite basis functions: on the other hand. restricting the equation to a sufficiently large bounded domain, Fourier techniques are applicable. For the time integration of the GPE, we study various exponential operator splitting methods of convergence orders two, four, and six. Our main objective is to provide accuracy and efficiency comparisons of exponential operator splitting Fourier and Hermite pseudospectral methods for the time evolution of the GPE. Furthermore, we illustrate the effectiveness of higher-order time-splitting methods compared to standard integrators in a long-term integration

Vortex reconnections in atomic condensates at finite temperature

The study of vortex reconnections is an essential ingredient of understanding superfluid turbulence, a phenomenon recently also reported in trapped atomic Bose-Einstein condensates. In this work we show that, despite the established dependence of vortex motion on temperature in such systems, vortex reconnections are actually temperature independent on the typical length/time scales of atomic condensates. Our work is based on a dissipative Gross-Pitaevskii equation for the condensate, coupled to a semiclassical Boltzmann equation for the thermal cloud (the Zaremba-Nikuni-Griffin formalism). Comparison to vortex reconnections in homogeneous condensates further show reconnections to be insensitive to the inhomogeneity in the background density.Comment: 6 pages, 4 figure

Qualidade de cocção de grãos de arroz translúcidos e gessados.

objetivou-se avaliar o comportamento de cocção dos grãos de arroz translúcidos e gessados e seus aspectos de qualidade

Características físicas dos grãos de arroz translúcidos e gessados.

Objetivou-se neste trabalho avaliar as características de transparência, brancura e grau de polimento dos grãos de arroz translúcidos e gessados

Efeito do tempo e condições de encharcamento sobre a estabilidade do farelo de arroz parboilizado.

O objetivo deste trabalho foi avaliar o efeito do tempo e da temperatura da água de encharcamento sobre a degradação hidrolítica e peroxidação do farelo de arroz na parboilização

Caracterização sensorial dos vinhos finos tranquilos e espumantes de regiões de altitudes de Santa Catarina.

Como convém a um dos melhores prazeres da vida, o vinho merece muita atenção. Nenhum processo de degustação de vinhos alcançou aceitação universal. Os julgadores de vinho mais experientes têm sua própria sequência de etapas a seguir. Embora todas sejam essenciais para uma degustação crítica, são muito detalhadas para um jantar. A diferença é equivalente ao abismo que separa a análise e o prazer da música

Use of pectin in the storage of mangaba fruits (Hancorniaspeciosa Gomes) associated with refrigeration

The objective of this study was to evaluate the storage potential of mangaba fruits coated with pectin biofilm stored in biochemical oxygen demand (BOD) (22 ± 1°C) under modified atmosphere. Scanning electron microscopy (SEM) was used to analyze the physical and chemical changes, vitamin C content, soluble solid, titratable acidity and turgor pressure, and colour and physical structure of the fruits during storage. The physico-chemical and colour analyses of the fruit were done with four treatment groups: control and pectin solutions of 4, 6 and 8% (w / v) at three day intervals for two weeks. The pectin solution and BOD were effective for the conservation of soluble solids of mangaba. However, the levels of acidity, vitamin C and turgor pressure showed that the fruits got ripe during the study and were kept until the sixth day of the test compared to control fruits. The best results were determined for the mangaba coated with 6 to 8% pectin.Key words: Conservation, film solution, post-harvest, firmness

Application of biofilms in the post-harvest conservation of pequi (Caryocar brasiliense Camb.)

Pequi (Caryocar brasiliense Camb.), fruit characteristic of the Brazilian cerrado, has sensory and nutritional characteristics, pleasant flavor and aroma and considerable presence of lipids and fiber, essential for human consumption. The aim of this study was to assess the post-harvest conservation of this fruit by using different sources of biofilms as a means to ensure the maintenance of fruit physical and chemical characteristics in order to increase its shelf life. Fruits were submitted to four treatments: control (no coating) (T1); 0.5% w/w carnauba wax (T2); 1% w/w cassava starch (T3) and 1.5% w/w xanthan gum (T4) stored during 15 days at BOD at 22 ± 0.1°C and submitted every three days to analyses of titratable acidity, soluble solid, pH, turgor pressure, vitamin C, weight loss and physical structure by scanning electron microscopy. The pH levels and turgor pressure showed expected values for control and coated pequi fruits. The vitamin C, titratable acidity, soluble solids contents and weight loss showed that coatings did not achieve satisfactory results. However, fruits coated with cassava starch showed the best conservation results during the experimental period.Key words: Coatings, shelf life, storage

Longe dos partidos e perto da federação: uma avaliação dos gastos municipais na saúde pública

The institutionalization of SUS made the municipalities important players in the public health policy. Thus, it was expected that the amount of resources allocated to public health would be determinate in some measure by the political party preferences. Given these political and institutional contexts, we analyzed the importance of the political party policies at the municipality level as a determinant of the expenditure on public health, as well was other conventional determinants of the expenditures on public health (region, per capita income, GDP, etc). Applying some econometric techniques (quantile regressions and econometric decomposition), we found that the parties’ political preferences have minor influence on the allocation of resources in public health. We conclude that the constitutional regulation (Constitutional Emend 29 or EC29) seems to be a more important determinant to explain the allocation of resources in the period 2002-2006 than the supposed political preferences announced by parties.SUS, health economics, Brazil