Some boundary effects in quantum field theory

We have constructed a quantum field theory in a finite box, with periodic boundary conditions, using the hypothesis that particles living in a finite box are created and/or annihilated by the creation and/or annihilation operators, respectively, of a quantum harmonic oscillator on a circle. An expression for the effective coupling constant is obtained showing explicitly its dependence on the dimension of the box.Comment: 12 pages, Late

Plantas medicinais utilizadas na medicina etnoveterinária praticada na ilha do Marajó.

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Effect of pre-treatment on açaí pulp microfiltration process.

Açaí (Euterpe oleracea Mart.) is a palm tree from north region of Brazil. Its small fruit is rich in bioactive compounds making it an attractive product. The aim of this work was to evaluate the effect of pre-treatments on microfiltration of açaí pulp. Raw material was acaí pulp from Belém, Brazil. Pre-treatments were centrifugation, conducted in a basket centrifuge; refining, in a depulper with a 0.5 ?m mesh; and enzymatic hydrolysis with DSM Rapidase and Picantase for 30 min at 35oC. Microfiltration was conducted in tubular membranes with 0.1?m pore size and 0.022m2 of surface. Processes were carried out at 35oC/3bar in batch mode. Permeate flux was determined during the process. Total and soluble solids, pH and acidity were determined on initial and treated pulp, permeate and retentate. Initial pulp contained 13.89 (w/w), 2.85oBrix, 0.19g/100g (malic acid) and 4.93 of pH. Total solids of treated pulp from centrifugation (5.71%) were lower than the others (13.83 and 13.84%) which consequently caused lower total solids in retentate and permeate fractions. Acidity and pH of treated pulp were different (p<0.05) for the different pre-treatments. Similar behaviors were also verified to retentate and permeate fractions. Values varied from 0.10 to 0.29 g/100g malic acid and pH from 4.17 to 4.98, with no correlation to total solids content. Soluble solids were different for each fraction although there was no significant difference in the same fraction in function of used pre-treatment. The values were 2.87, 1.63 and 4.77oBrix for treated pulp, permeate and retentate, respectively. Average flux was affected by pre-treatment being the lowest values, around 70 L/hm2, obtained after centrifugation and the highest, 110 L/hm2, with the enzymatic action. As physical-chemical parameters did not present a behavior that contributes for the pre-treatment selection, permeate flux results suggest the use of enzyme as the recommended option

Two-dimensional superconductivity at the (111)LaAlO3_3/SrTiO3_3 interface

We report on the discovery and transport study of the superconducting ground state present at the (111)LaAlO$_3$/SrTiO$_3$ interface. The superconducting transition is consistent with a Berezinskii-Kosterlitz-Thouless transition and its 2D nature is further corroborated by the anisotropy of the critical magnetic field, as calculated by Tinkham. The estimated superconducting layer thickness and coherence length are 10 nm and 60 nm, respectively. The results of this work provide a new platform to clarify the microscopic details of superconductivity at LaAlO$_3$/SrTiO$_3$ interfaces, in particular in what concerns the link with orbital symmetry.Comment: 4 pages, 4 figure

Biological and morphometric aspects and rearing of Syssphinx molina (Cramer) (Lepidoptera: Saturniidae), a defoliator of parica tree.

O objetivo desse trabalho foi descrever os aspectos biológicos e morfométricos da lagarta desfolhadora do paricá, Syssphinx molina (Cramer), e fazer recomendações para a criação do inseto. O ciclo de vida foi de 62,9 dias com períodos médios para as fases de ovo, lagarta, pré-pupa e pupa de 5,6; 31,1; 2,2 e 16,6 dias, respectivamente. A viabilidade das pupas foi de 60,5% para fêmeas e 48,6% nos machos. A razão sexual foi de 0,5 e a produção média de 182,3 ± 2,2 ovos por fêmea com viabilidade de ovos de 24,3%. A longevidade média foi de 7,9 ± 2 e 8,1 ± 3 dias para fêmeas e machos, respectivamente. Outros parâmetros foram igualmente observados e comparados com a descrição de outras espécies de Saturniidae