8,375 research outputs found

    Single-Particle Density of States of a Superconductor with a Spatially Varying Gap and Phase Fluctuations

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    Recent experiments have shown that the superconducting energy gap in some cuprates is spatially inhomogeneous. Motivated by these experiments, and using exact diagonalization of a model d-wave Hamiltonian, combined with Monte Carlo simulations of a Ginzburg-Landau free energy functional, we have calculated the single-particle density of states LDOS(ω,r)(\omega,r) of a model high-Tc_c superconductor as a function of temperature. Our calculations include both quenched disorder in the pairing potential and thermal fluctuations in both phase and amplitude of the superconducting gap. Most of our calculations assume two types of superconducting regions: α\alpha, with a small gap and large superfluid density, and β\beta, with the opposite. If the β\beta regions are randomly embedded in an α\alpha host, the LDOS on the α\alpha sites still has a sharp coherence peak at T=0T = 0, but the β\beta component does not, in agreement with experiment. An ordered arrangement of β\beta regions leads to oscillations in the LDOS as a function of energy. The model leads to a superconducting transition temperature TcT_c well below the pseudogap temperature Tc0T_{c0}, and has a spatially varying gap at very low TT, both consistent with experiments in underdoped Bi2212. Our calculated LDOS(ω,r)(\omega,r) shows coherence peaks for TTcT T_c, in agreement with previous work considering phase but not amplitude fluctuations in a homogeneous superconductor. Well above TcT_c, the gap in the LDOS disappears.Comment: 37 pages, 12 figures. Accepted by Phys. Rev. B. Scheduled Issue: 01 Nov 200

    Sputter-deposited fuel cell membranes and electrodes

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    A method for preparing a membrane for use in a fuel cell membrane electrode assembly includes the steps of providing an electrolyte membrane, and sputter-depositing a catalyst onto the electrolyte membrane. The sputter-deposited catalyst may be applied to multiple sides of the electrolyte membrane. A method for forming an electrode for use in a fuel cell membrane electrode assembly includes the steps of obtaining a catalyst, obtaining a backing, and sputter-depositing the catalyst onto the backing. The membranes and electrodes are useful for assembling fuel cells that include an anode electrode, a cathode electrode, a fuel supply, and an electrolyte membrane, wherein the electrolyte membrane includes a sputter-deposited catalyst, and the sputter-deposited catalyst is effective for sustaining a voltage across a membrane electrode assembly in the fuel cell

    The Effect of Innovative Leadership, Employees’ Innovative Knowledge and Skills on the Innovative Work Behavior of Employees: Management

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    The study aims to examine the effect of innovative leadership of administrators, innovative knowledge, and innovative skills of employees on the innovative work behaviour of employees. To deepen the concept of the study, the literature was reviewed. The study used a descriptive assessment and correlational research design. The population of the study was all the employees of the two colleges (DWCL & DWCV). To gather the data, validated research questionnaires were used. The results of the statistical analysis suggest that the innovative leadership of administrators, innovative knowledge, innovative skills and innovative work behaviour of the employees are considered high. The Pearson r correlation found that there is a significant correlation between innovative leadership, innovative knowledge, innovative skills and innovative work behaviour of the employees. The result of the study contributes to enriching the current discussion on the innovative work behaviour of employees

    Different Harvest Schedules to Prepare Deferred Forage from C4 Grasses in Córdoba, Argentina

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    From 1995 until 1999 a trial was done in the fields of the Universidad Nacional de Córdoba with four C4 forage grasses. These fields lie in the subtropical and semiarid region of Argentina. This research aimed to identify forage species that could be used as deferred forage for the drier and cooler winter season. Four species of C4 grasses were used: Rhodesgrass (Chloris gayana Kunth), Gatton (Panicum maximum), coloratum (Panicum coloratum) and digitgrass (Digitaria eriantha), respectively. Two growing periods were used: full season growth (FS) and half season regrowth (HS), in both cases the deferred forage was harvested three times: at the beginning, in the middle and at the end of the winter. This paper foccuses DM yields in kg/hectare (DM) and percentage of crude protein (CP). The HS yields less but shows better CP than the FS, therefore it may be a better forage in winter. Coloratum and digigrass seems to give better deferred forage than the other species

    Observations of Stellar Objects at a Shell Boundary in the Star-Forming Complex in the Galaxy IC1613

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    The single region of ongoing star formation in the galaxy IC 1613 has been observed in order to reveal the nature of compact emission-line objects at the edges of two shells in the complex, identified earlier in H-alpha line images. The continuum images show these compact objects to be stars. Detailed spectroscopic observations of these stars and the surrounding nebulae were carried out with an integral field spectrograph MPFS mounted on the 6m telescope of the Special Astrophysical Observatory. The resulting stellar spectra were used to determine the spectral types and luminosity classes of the objects. An Of star we identified is the only object of this spectral type in IC 1613. The results of optical observations of the multi-shell complex are compared to 21cm radio observations. The shells harboring the stars at their boundaries constitute the most active part of the star-forming region. There is evidence that shocks have played an important role in the formation of the shells.Comment: 10 pages, 5 PS and 1 color JPEG figur

    Validación de método de registración CT-MR aplicado a pacientes epilépticos

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    El objetivo de este trabajo es la validación de un método de registración que permite cuantificar su eficacia para determinar la transformación espacial que mejor ajusta la conversión de coordenadas desde el espacio de la Tomografía Computada (CT) al espacio de Resonancia Magnética (MR) para su aplicación en pacientes epilépticos. Los resultados obtenidos del Error de Registración (TRE del inglés Target Registration Error) y los resultados obtenidos del error en cada punto marcado presentan una marcada variación entre ellos. Esta variación también es observada entre los valores de los distintos sujetos. Los resultados obtenidos en la validación de este método son aceptables desde el punto de vista de la registración de imágenes. Para la determinación de la posición espacial del foco epileptógeno se encuentra en el límite superior de lo tolerable. Los valores de error de registración en los tres casos analizados son superiores, aunque en el mismo orden de magnitud del máximo error permisible.Sociedad Argentina de Informática e Investigación Operativ

    Human Urocortin 2, a Corticotropin-Releasing Factor (CRF) 2

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