3,330 research outputs found
Width and Magnetic Field Dependence of Transition Temperature in Ultranarrow Superconducting Wires
We calculate the transition temperature in ultranarrow superconducting wires
as a function of wire width, resistance and applied magnetic field. We compare
the results of first-order perturbation theory and the non-perturbative
resummation technique developed by Oreg and Finkel'stein. The latter technique
is found to be superior as it is valid even in the strong disorder limit. In
both cases the predicted additional suppression of the transition temperature
due to the reduced dimensionality is strongly dependent upon the boundary
conditions used. When we use the correct (zero-gradient) boundary conditions,
we find that theory and experiment are consistent, although more experimental
data is required to verify this systematically. We calculate the magnetic field
dependence of the transition temperature for different wire widths and
resistances in the hope that this will be measured in future experiments. The
predicted results have a rich structure - in particular we find a dimensional
crossover which can be tuned by varying either the width of the wire or its
resistance per square.Comment: 12 pages, 1 table, 7 figures. The changes made to the paper are ones
of emphasis. The comparison between theory and experiment has been altered,
and detailed comparisons of various approximations have been omitted,
although the results are summarised in the paper. Much more emphasis has been
placed on the new predictions of the effect of an applied magnetic field on
transition temperature in wires (Figs. 5-7
Generating Bounds for the Ground State Energy of the Infinite Quantum Lens Potential
Moment based methods have produced efficient multiscale quantization
algorithms for solving singular perturbation/strong coupling problems. One of
these, the Eigenvalue Moment Method (EMM), developed by Handy et al (Phys. Rev.
Lett.{\bf 55}, 931 (1985); ibid, {\bf 60}, 253 (1988b)), generates converging
lower and upper bounds to a specific discrete state energy, once the signature
property of the associated wavefunction is known. This method is particularly
effective for multidimensional, bosonic ground state problems, since the
corresponding wavefunction must be of uniform signature, and can be taken to be
positive. Despite this, the vast majority of problems studied have been on
unbounded domains. The important problem of an electron in an infinite quantum
lens potential defines a challenging extension of EMM to systems defined on a
compact domain. We investigate this here, and introduce novel modifications to
the conventional EMM formalism that facilitate its adaptability to the required
boundary conditions.Comment: Submitted to J. Phys.
On the importance of background subtraction in the analysis of coronal loops observed with TRACE
In the framework of TRACE coronal observations, we compare the analysis and
diagnostics of a loop after subtracting the background with two different and
independent methods. The dataset includes sequences of images in the 171 A, 195
A filter bands of TRACE. One background subtraction method consists in taking
as background values those obtained from interpolation between concentric
strips around the analyzed loop. The other method is a pixel-to-pixel
subtraction of the final image when the loop had completely faded out, already
used by Reale & Ciaravella 2006. We compare the emission distributions along
the loop obtained with the two methods and find that they are considerably
different. We find differences as well in the related derive filter ratio and
temperature profiles. In particular, the pixel-to-pixel subtraction leads to
coherent diagnostics of a cooling loop. With the other subtraction the
diagnostics are much less clear. The background subtraction is a delicate issue
in the analysis of a loop. The pixel-to-pixel subtraction appears to be more
reliable, but its application is not always possible. Subtraction from
interpolation between surrounding regions can produce higher systematic errors,
because of intersecting structures and of the large amount of subtracted
emission in TRACE observations.Comment: 9 pages, 9 figure
Development of a Computerized App Based on Fitness Norms of University Students
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Benchmark full configuration-interaction calculations on HF and NH2
Full configuration-interaction (FCI) calculations are performed at selected geometries for the 1-sigma(+) state of HF and the 2-B(1) and 2-A(1) states of NH2 using both DZ and DZP gaussian basis sets. Higher excitations become more important when the bonds are stretched and the self-consistent field (SCF) reference becomes a poorer zeroth-order description of the wave function. The complete active space SCF - multireference configuration-interaction (CASSCF-MRCI) procedure gives excellent agreement with the FCI potentials, especially when corrected with a multi-reference analog of the Davidson correction
Physiological modulation of iron metabolism in rainbow trout (Oncorhynchus mykiss) fed low and high iron diets
Iron (Fe) is an essential element, but Fe metabolism is poorly described in fish and the role of ferrireductase and transferrin in iron regulation by teleosts is unknown. The aim of the present study was to provide an overview of the strategy for Fe handling in rainbow trout, Oncorhynchus mykiss. Fish were fed Fe-deficient, normal and high-Fe diets (33, 175, 1975 mg Fe kg-1 food, respectively) for 8 weeks. Diets were chosen so that no changes in growth, food conversion ratio, haematology, or significant oxidative stress (TBARS) were observed. Elevation of dietary Fe caused Fe accumulation particularly in the stomach, intestine, liver and blood. The increase in total serum Fe from 10 to 49 μmol l-1 over 8 weeks was associated with elevated total Fe binding capacity and decreased unsaturated Fe binding capacity, so that in fish fed a high-Fe diet transferrin saturation increased from 15% at the start of the experiment to 37%. Fish on the high-Fe diet increased Fe accumulation in the liver, which was correlated with elevation of hepatic ferrireductase activity and serum transferrin saturation. Conversely, fish on the low-Fe diet did not show tissue Fe depletion compared with normal diet controls and did not change Fe binding to serum transferrin. Instead, these fish doubled intestinal ferrireductase activity which may have contributed to the maintenance of tissue Fe status. The absence of clear treatment-dependent changes in branchial Fe accumulation and ferrireductase activity indicated that the gills do not have a major role in Fe metabolism. Some transient changes in Cu, Zn and Mn status of tissues occurred.Facultad de Ciencias Naturales y Muse
Financial Inclusion: Lessons From Rural South India
Financial inclusion/exclusion has recently been emphasised as an important policy option aimed at alleviating poverty, minimising social exclusion and enhancing economic growth. In this article, we review the growing interest in financial exclusion and inclusion, define them and demonstrate their existence in developing and developed countries. Our empirical focus is on whether financial inclusion has been successfully implemented in four sites in rural South India where banks claimed that financial inclusion is complete. Although many rural people in South India are financially included, the concept of financial inclusion is more complex than usually portrayed. Our findings show that social and personal deprivation contributes to financial exclusion and should be viewed as key barriers to financial inclusion. We also suggest that financial inclusion is not a monolithic phenomenon and should be studied in a multi-layered fashion, ranging from having a bank account to making full use of modern financial instruments
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