4,425 research outputs found

    The impact of COVID-19 on memory: Recognition for masked and unmasked faces

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    Considering the current state of the worldwide pandemic, it is still common to encounter people wearing face protection masks. Although a safety measure against COVID-19, face masks might be compromising our capacity for face recognition. We conducted an online study where 140 participants observed masked and unmasked faces in a within-subjects design and then performed a recognition memory task. The best performance was found when there were no masks either at study and test phase, i.e., at the congruent unmasked condition. The worst performance was found for faces encoded with a mask but tested without it (i.e., masked-unmasked incongruent condition), which can be explained by the disruption in holistic face processing and the violation of the encoding specificity principle. Interestingly, considering the unmasked-masked incongruent condition, performance was probably affected by the violation of the encoding specificity principle but protected by holistic processing that occurred during encoding.info:eu-repo/semantics/publishedVersio

    Validade de algumas equações de drenagem para espaçamento de drenos cobertos. I. Regime de escoamento permanente.

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    Teorias de drenagem em regime de escoamento permanente, para obtenção de valores de espaçamento entre drenos foram testadas a partir dos parâmetros de um modelo físico de laboratorio, utilizando-se dois tipos de solos de várzeas: solo mineral e solo orgânico. A condutividade hidráulica saturada de cada um dos dois tipos de material poroso foi obtida, com o proprio modelo físico, medindo-se a posição do lençol freatico. 0 valor real do espaçamento (149,0 cm) no modelo físico foi comparado com os valores estimados por meio das teorias de Donnan-Hooghoudt, de Hooghoudt c de Kirkham, válidas para regime de escoamento permanente. Quando considerados em conjunto os dois tipos de solo de várzeas, na situação ern que o tubo de dreno estava. a certa distância da camada impermeável), a teoria de Donnan-Hooghoudt foi de grande eficiencia, dando um valor médio do espaçamento estimado (154,5 cm) bem proximo do real (149,0 cm) e em coeficiente de variado baixo (9,5%). Na condição em que o tubo de dreno tocava. a camada impermeável, as teorias de Donnan-Hooghoudt e de Hooghoudt mostraram-se ineficazes para qualquer tipo de material poroso. A ordem de preferencia das teorias foi a seguinte: Donnan-Hooghoudt, Hooghoudt, e Kirkham

    Finite Size Effects in Thermal Field Theory

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    We consider a neutral self-interacting massive scalar field defined in a d-dimensional Euclidean space. Assuming thermal equilibrium, we discuss the one-loop perturbative renormalization of this theory in the presence of rigid boundary surfaces (two parallel hyperplanes), which break translational symmetry. In order to identify the singular parts of the one-loop two-point and four-point Schwinger functions, we use a combination of dimensional and zeta-function analytic regularization procedures. The infinities which occur in both the regularized one-loop two-point and four-point Schwinger functions fall into two distinct classes: local divergences that could be renormalized with the introduction of the usual bulk counterterms, and surface divergences that demand countertems concentrated on the boundaries. We present the detailed form of the surface divergences and discuss different strategies that one can assume to solve the problem of the surface divergences. We also briefly mention how to overcome the difficulties generated by infrared divergences in the case of Neumann-Neumann boundary conditions.Comment: 31 pages, latex, to appear in J. Math. Phy

    New results for the t-J model in ladders: Changes in the spin liquid state with applied magnetic field. Implications for the cuprates

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    Exact Diagonalization calculations are presented for the t-J model in the presence of a uniform magnetic field. Results for 2xL ladders (L=8,10,12) and 4x4 square clusters with 1 and 2 holes indicate that the diamagnetic response to a perpendicular magnetic field tends to induce a spin liquid state in the spin background. The zero-field spin liquid state of a two-leg ladder is reinforced by the magnetic field: a considerable increase of rung antiferromagnetic correlations is observed for J/t up to 0.6, for 1 and 2 holes. Pair-breaking is also clearly observed in the ladders and seems to be associated in part with changes promoted by the field in the spin correlations around the zero-field pair. In the 4x4 cluster, the numerical results seem to indicate that the field-induced spin liquid state competes with the zero-field antiferromagnetic short-range-order, the spin liquid state being favored by higher doping and smaller values of J/t. It is interesting to note that the field-effect can also be observed in a 2x2 plaquette with 1 and 2 holes. This opens up the possibility of gaining a qualitative understanding of the effect.Comment: 16 pages, 7 figures, latex New results adde

    Characterization of watermelon juice concentrated by reverse osmosis process.

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    Watermelon is a tropical fruit with excellent flavour, color, sweetness and succulence. Nowadays it is pointed out as an excellent source of lycopene, a carotenoid with antioxidant property. The objective of this work was to concentrate watermelon juice by reverse osmosis to obtain a concentrated product rich in lycopene. The juice was obtained by the depulping the fruits in a finisher with a 0.8 mm. Reverse osmosis was carried out in a pilot plant unit with composite membranes (conditioned in a plate and frame module. totalizing a permeate area of 0.72m2. The process was carried out at 30ºC, 60 bar and 650 L/h flow rate. Samples Lycopene content was determined by extraction with hexane measured in spectrophotometer at 503 nm. Antioxidant capacity s was evaluated by extraction with hexane followed by the quantification using ABTS as radical and Trolox as standard. The color loss was determined in spectrophotometer at 734nm after 15 min of reaction of the sample with the ABTS. The mean permeate flux was 22L1h1m

    Particle Creation by a Moving Boundary with Robin Boundary Condition

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    We consider a massless scalar field in 1+1 dimensions satisfying a Robin boundary condition (BC) at a non-relativistic moving boundary. We derive a Bogoliubov transformation between input and output bosonic field operators, which allows us to calculate the spectral distribution of created particles. The cases of Dirichlet and Neumann BC may be obtained from our result as limiting cases. These two limits yield the same spectrum, which turns out to be an upper bound for the spectra derived for Robin BC. We show that the particle emission effect can be considerably reduced (with respect to the Dirichlet/Neumann case) by selecting a particular value for the oscillation frequency of the boundary position
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