Search results for "COPI"
showing 10 items of 2618 documents
Exciton recombination dynamics inInAs∕InPself-assembled quantum wires
2005
In this work we investigate the exciton recombination dynamics in InAs/ InP semiconductor self-assembled quantum wires, by means of continuous wave and time resolved photoluminescence. The continuous wave photoluminescence results seem to indicate that the temperature quenching of the emission band seems to be more probably due to unipolar thermal escape of electrons towards the InP barrier. On the other hand, the analysis of time resolved photoluminescence reveals that the temperature dependence of the radiative and nonradiative recombination times is mainly determined by the dynamics of excitons localized by disorder shigh energy tail of the PL bandd and strongly localized slow energy tai…
Mesoscopic gels at low agarose concentration: perturbation effects of ethanol
1997
Aqueous agarose solutions at low concentrations (0.5 g/liter) were temperature quenched below the spinodal line to form mutually disconnected mesoscopic gels. In the presence of 6% ethanol, these solutions, obtained by quenching at the same temperature depth as in pure water, appear much more fluid, as determined by probe diffusion experiments. We show by static and dynamic light scattering that this can be explained by the solvent-mediated effects of ethanol, leading to a globular shape of mesoscopic agarose gels, rather than to an extended rodlike structure observed in pure water. Our findings show the significant effects of solvent perturbations on particle condensation and, therefore, m…
Mindfulness, rumination, and coping skills in young women with Eating Disorders: A comparative study with healthy controls
2019
Eating Disorders (ED) have been associated with dysfunctional coping strategies, such as rumination. Promoting alternative ways of experiencing mental events, based on a mindfulness approach, might be the clue for learning more effective coping and regulatory strategies among young women with ED. This study examined the comparison between patients with ED diagnosis and healthy subjects in mindfulness, rumination and effective coping. In addition, we analyzed the independent association of those with the presence of ED. The study sample was formed by two groups of young women ranged 13-21 years: Twenty-five with an ED diagnosis and 25 healthy subjects. They were assessed by using the Freibur…
When and how do hospital nurses cope with daily stressors? A multilevel study
2020
BackgroundDuring their workday, nurses face a variety of stressors that are dealt with using different coping strategies. One criticism of the contextual models of work stress is that they fail to focus on individual responses like coping with stress. Neverthless, little is know about the momentary determinants of coping in nurses.ObjectivesTo identify the momentary predictors of problem-focused approaching coping and emotion-focused approaching coping, as well as those for seeking social support and refusal coping strategies, during the working day in nurses.DesignThis study uses descriptive, correlational, two-level design with repeated measures.SettingsWards of two University hospitals.P…
Medidas a tomar de cara a la adaptación de registros RDA en el catálogo
2013
La adopción del nuevo estandar de catalogación RDA (Resource Description and Access) por un número creciente de bibliotecas de todo el mundo, está afectando ya a las tareas de catalogación en bibliotecas universitarias. En el contexto español, el uso de RDA no parece inmediato, sin embargo, la presencia de registros RDA en los catálogos que se utilizan habitualmente como fuentes para la catalogación por copia, hace necesario tomar medidas que garanticen su integración coherente con los datos ya presentes en el catálogo, creados con normativas catalográficas distintas. Esta presentación ofrece un resumen de los principales cambios que supone RDA en los registros MARC21, los pasos que hay que…
A Methodology to Deduce the Microstructural Spatial Deformation of Polycrystalline Structures: Application to the Alloy 600
2009
Studying the corrosion of the alloy 600, under water pressure, is of high importance to understand the ageing process of pressurized water reactors. Today, the impact of the oxide growth on the mechanical properties of nickel alloys is a challenge. The surface analysis and the quantification of the local deformation are key factors to deduce the surface damage of the substrate produced by corrosion. Here, we introduce a new methodology to determine the deformation distribution of the alloy 600 by using polycrystalline samples. The method is based on nanopads disposed on the surface samples, which allow a mapping, at the microscopic scale, of the spatial deformation. We applied to the sample…
Poisoning histories in the Italian renaissance: The case of Pico Della Mirandola and Angelo Poliziano.
2018
Giovanni Pico della Mirandola and Angelo Poliziano were two of the most important humanists of the Italian Renaissance. They died suddenly in 1494 and their deaths have been for centuries a subject of debate. The exhumation of their remains offered the opportunity to study the cause of their death through a multidisciplinary research project. Anthropological analyses, together with documentary evidences, radiocarbon dating and ancient DNA analysis supported the identification of the remains attributed to Pico. Macroscopic examination did not reveal paleopathological lesions or signs related to syphilis. Heavy metals analysis, carried out on bones and mummified tissues, showed that in Pico's…
Phonon Cooling of Nanomechanical Beams with Tunnel Junctions
2009
We demonstrate electronic cooling of 1D phonon modes in suspended nanowires for the first time, using normal-metal-insulator-superconductor (N-I-S) tunnel junctions. Simultaneous cooling of both electrons and phonons to a common temperature was achieved. In comparison with nonsuspended devices, better cooling performance is achieved in the whole operating range of bath temperatures between 0.1-0.7 K. The observed low-temperature thermal transport characteristics are consistent with scattering of ballistic phonons at the nanowire-bulk contact as being the mechanism limiting thermal transport. At the lowest bath temperature of the experiment approximately 100 mK, both phonons and electrons in…
Raman study of strain in GaN/AlN quantum dot multilayered structures
2005
Raman spectroscopy has been used to investigate self-assembled stacks of GaN/AlN quantum dots with increasing number of periods. The E2H phonon modes associated to GaN and AlN are clearly resolved with visible excitation, and their energies allow the simultaneous monitoring of the dot and barrier strain states. The compression of the quantum dots is evidenced by a shift of the E2H phonon mode of circa 29 cm–1 to higher energies with respect to its relaxed value. The strain of the AlN spacer is found to be correlated to that of the dot, with an increase in its tensile component for the samples with fewer periods and a partial relaxation for samples over 50 periods. Additionally, resonant eff…
Raman Spectroscopy and Low-Temperature Transport Measurements of Individual Single-Walled Carbon Nanotubes with Varying Thickness
2009
We have investigated two metallic and one semiconducting individual single-walled carbon nanotubes (SWNT) and one bundle of two semiconducting nanotubes with a diameter range 1.1−2.9 nm with Raman spectroscopy and low-temperature electric transport measurements. With these two methods, we obtain mutually independent measurements on the basic properties of a specific nanotube. In particular, we obtain data on metallic and semiconducting properties. Evidence of a small band gap for one metallic tube was obtained. For the semiconducting SWNTs with diameters of 2.7−2.9 nm, a special resonance condition was observed which causes an anomalous intensity ratio for the two components of the G-band. …