3,656 research outputs found

    Time-dependent Robin boundary conditions in the dynamical Casimir effect

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    Motivated by experiments in which moving boundaries are simulated by time-dependent properties of static systems, we discuss the model of a massless scalar field submitted to a time-dependent Robin boundary condition (BC) at a static mirror in 1+1 dimensions. Using a perturbative approach, we compute the spectral distribution of the created particles and the total particle creation rate, considering a thermal state as the initial field state.Comment: 10 pages, 3 figures. To appear in proceedings of Conference on Quantum Field Theory under the Influence of External Condition

    Drying kinetics and physico-chemical quality of mango slices

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    Mango (Mangifera indica L.) is an important tropical fruit consumed worldwide and grown in Italy only in Sicily, where the areas of the Tyrrhenian coast have proved to be suitable to produce valuable fruits. Mango fruit has a pleasant aroma and taste, which are important qualities for consumer’s sensorial acceptance. However, they are highly perishable, prone to progressive undesired changes if stored untreated, resulting in around 25% postharvest losses, which is further increased during storage and transportation. An alternative for reducing the above-mentioned undesired changes is the dehydration of the cut fruit, which reduce the fruit water activity, thereby avoiding the deteriorative process and extending the shelf-life. This study investigates the effect of dehydration at different temperatures (50, 60 and 70°C) on drying kinetics and volatile compounds of two cultivars (Keitt and Osteen) of mango fruits cultivated in Sicily. Significant losses of volatile constituents of fresh mango occurred at higher temperature, especially for the Osteen cultivar. A diffusion model including the effect of shrinkage is also proposed, which may be used to describe drying behaviour of fruits and to define the optimal drying conditions.. Experimental data of the moisture ratio during drying were well predicted by the model

    The wave energy flux of high frequency diffracting beams in complex geometrical optics

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    We consider the construction of asymptotic solutions of Maxwell's equations for a diffracting wave beam in the high frequency limit and address the description of the wave energy flux transported by the beam. With this aim, the complex eikonal method is applied. That is a generalization of the standard geometrical optics method in which the phase function is assumed to be complex valued, with the non-negative imaginary part accounting for the finite width of the beam cross section. In this framework, we propose an argument which simplifies significantly the analysis of the transport equation for the wave field amplitude and allows us to derive the wave energy flux. The theoretical analysis is illustrated numerically for the case of electron cyclotron beams in tokamak plasmas by using the GRAY code [D. Farina, Fusion Sci. Technol. 52, 154 (2007)], which is based upon the complex eikonal theory. The results are compared to those of the paraxial beam tracing code TORBEAM [E. Poli et al., Comput. Phys. Commun. 136, 90 (2001)], which provides an independent calculation of the energy flow

    Lepton-nucleus scattering in the impulse approximation regime

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    We discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out using realistic nuclear spectral functions and including the effect of final state interactions. Comparison between electron scattering data and the calculated inclusive cross sections off oxygen shows that the Fermi gas model fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed. The role of Pauli blocking in charged-current neutrino induced reactions at low Q2Q^2 is also analyzed.Comment: To be published in the Proceedings of NUFACT05 (Nucl. Phys. B, Proceedings Supplements

    The self on the page: Using student teachers\u27 written stories as a reflective tool during the student teaching internship

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    Current traditional reflective practices in teacher preparation may be failing to address the needs of teacher candidates in terms of their identity formation as teachers. This qualitative study, utilizing a participant group of six graduate students in their student teaching internships at a small public liberal arts university, explored whether writing stories could enable student teachers to make better sense of their internship experiences and develop understanding of who they are as teachers. After an initial training session on story, data were collected at three key points during the student teacher internship. This data consisted of participants\u27 written stories, focus group discussions, and individual exit interviews. The data were then systematically coded using grounded theory methodology. The six themes resulting from this study indicate support for written stories as an alternative or parallel reflective tool to traditional journaling in teacher preparation

    Analysis of aroma compounds of nine autochthonous and non-autochthonous loquat cultivars grown in Sicily

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    Loquat cultivation in Sicily is mainly based on nonnative cultivars and local ecotypes characterized by high nutraceutical value and appreciable physicochemical characteristics. Increased interest in commercial loquat production has increased the intention to provide premium quality loquat cultivars that include volatile substances capable of conditioning the sensorial properties and, therefore, the acceptability of fruits by consumers. This study determined the content of volatile compounds in nonnative and local loquat fruits grown in Sicily. Analyses were performed on five international cultivars and four local cultivars
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