44 research outputs found

    Group Approach to the Quantization of the P\"oschl-Teller dynamics

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    The quantum dynamics of a particle in the Modified P\"oschl-Teller potential is derived from the group SL(2,R)SL(2,R) by applying a Group Approach to Quantization (GAQ). The explicit form of the Hamiltonian as well as the ladder operators is found in the enveloping algebra of this basic symmetry group. The present algorithm provides a physical realization of the non-unitary, finite-dimensional, irreducible representations of the SL(2,R)SL(2,R) group. The non-unitarity manifests itself in that only half of the states are normalizable, in contrast with the representations of SU(2) where all the states are physical.Comment: 17 pages, LaTe

    Vanadium Inhalation in a Mouse Model for the Understanding of Air-Suspended Particle Systemic Repercussion

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    There is an increased concern about the health effects that air-suspended particles have on human health which have been dissected in animal models. Using CD-1 mouse, we explore the effects that vanadium inhalation produce in different tissues and organs. Our findings support the systemic effects of air pollution. In this paper, we describe our findings in different organs in our conditions and contrast our results with the literature

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

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    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

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    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

    Data for: Evolution of the external quantum efficiency of Si-based PV minimodules with encapsulated down-shifters and aged under UV radiation

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    Raw data of the manuscript (EQE spectra and UV degradation

    Data for: Evolution of the external quantum efficiency of Si-based PV minimodules with encapsulated down-shifters and aged under UV radiation

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    Raw data of the manuscript (EQE spectra and UV degradation)THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

    Optical anisotropy and EO properties of ferroelectrics TGS and LHP single crystals using a HAUP technique

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    Triglycine sulphate, (NH2CH2CO2H)3⋅H2SO4(\rm NH_2CH_2CO_2H)_3\cdot H_2SO_4 (TGS), is a ferroelectric crystal widely used in optical properties studies, phase transitions theory as well as test for experimental techniques. Lead monohydrogen phosphate, PbHPO4 (LHP), is a typical representative of the family of ferroelectric schultenites, suitable in testing microscopic theories of ferroelectricity. In this work the so-called high-accuracy universal polarimeter (HAUP) has been used to determine the natural anisotropy in the birefringent crystalline sections (010), obtaining the temperature dependence of optical anisotropy magnitudes of the crystal: gyrotropy, birefringence and optical indicatrix rotation. Our HAUP technique also permits to investigate the electro-optic (EO) coefficients associated to the phases above and below phase transition temperatures

    Depth-resolved microspectroscopy of porous silicon multilayers

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    3 pages, 3 figures.We have measured depth-resolved microphotoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. The PL emission band gets stronger, blueshifts, and narrows at the high porosity layers. On the contrary, the Raman band weakens and broadens. This band is fitted to the phonon confinement model. With the bulk silicon phonon frequency and its linewidth as free parameters, we obtain crystallite size, temperature, and stress as a function of depth. Sizes are larger than those estimated from PL. Laser power was reduced to eliminate heating effects. Compressive stresses in excess of 10 kbar are found in the deepest layer due to the lattice mismatch with the substrate.The authors acknowledge financial support from the Spanish CICyT (Project Nos. MAT96-0395-CP and MAT97- 0725).Peer reviewe
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