20,685 research outputs found
Crossed conductance in FSF double junctions: role of out-of-equilibrium populations
We discuss a model of Ferromagnet / Superconductor / Ferromagnet (FSF) double
junction in which the quasiparticles are not in equilibrium with the condensate
in a region of the superconductor containing the two FS contacts. The role of
geometry is discussed, as well as the role of a small residual density of
states within the superconducting gap, that allows a sequential tunneling
crossed current. With elastic quasiparticle transport and the geometry with
lateral contacts, the crossed conductances in the sequential tunneling channel
are almost equal in the normal and superconducting phases, if the distance
between the FS interfaces is sufficiently small. The sequential tunneling and
spatially separated processes (the so-called crossed Andreev reflection and
elastic cotunneling processes) lead to different signs of the crossed current
in the antiparallel alignment for tunnel interfaces.Comment: 8 pages, 4 figure
Why some fields might be rectangular: an exploration of agricultural landscapes between pre-capitalist and capitalist modes of production
This article is a preliminary investigation of possible spatial form which starts by rejecting the idea that spatial theory can be built from assumptions of isomorphism. It examines spatial form in high potential ridge valley areas which are densely populated, and identifies the transition in land configuration for pre-capitalist to capitalist modes of production. In building the argument simple geometric patterns that differentiate from the model are postulated. The basic drivers of the differing spatial systems are essentially the superstructural legal conditions which are postulated as a moving from communal, customary law to individual statutory property rights
Drive mechanism for production of simulated human breath
Simulated breath drive mechanism was developed as subsystem to breathing metabolic simulator. Mechanism reproduces complete range of human breath rate, breath depth, and breath waveform, as well as independently controlled functional residual capacity. Mechanism was found capable of simulating various individual human breathing characteristics without any changes of parts
Current rectification in molecular junctions produced by local potential fields
The transport properties of a octane-dithiol (ODT) molecule coupled to
Au(001) leads are analyzed using density functional theory and non-equilibrium
Green functions. It is shown that a symmetric molecule can turn into a diode
under influence of a local electric field created by an external charged probe.
The origin of the asymmetry of the current--voltage () dependence is
traced back to the appearance of a probe induced quasi--local state in the
pseudogap of the ODT molecule. The induced state affects electron transport,
provided it is close to the Fermi level of the leads. An asymmetric placement
of the charged probe along the alkane chain makes the induced quasi--local
state in the energy gap very sensitive to the bias voltage and results in
rectification of the current. The results based on DFT are supported by
independent calculations using a simple one--particle model Hamiltonian.Comment: 7 pages, 6 figure
Investigation of tidal displacements of the Earth's surface by laser ranging to GEOS-3
An analysis of laser ranging data from three stations was carried out in an attempt to measure the geometric Earth tide. Two different approaches to the problem were investigated. The dynamic method computes pass to pass apparent movements in stations height relative to short arcs fitted to several passes of data from the same station by the program GEODYNE. The quasi-geometric method reduces the dependence on unmodelled satellite dynamics to a knowledge of only the radial position of the satellite by considering two station simultaneous ranging at the precise time that the satellite passes through the plane defined by two stations and the center of mass of the Earth
Selection Response for Increased Grain Yield in Two High Oil Maize Synthetics
Selection for increased oil level in maize showed the increase was associated with decrease in starch concentration, kernel weight, and grain yield. The study was conducted with the objectives: (1) to evaluate response to six cycles for increased grain yield in the high oil maize Alexho Elite (AE: 60-90 g kg-1 oil concentration) and Ultra High Oil (UHO: 100-140 g kg-1 oil concentration) using inbred tester B73; (2) to measure responses to selection for increased grain yield with changes in yield components; and (3) to determine a suitable tester. Previously the two synthetics had been selected for oil concentration. After six cycles, the six genotypes i.e. AE C0, AE C3, AE C6, UHO C0, UHO C3, and UHO C6 were testcrossed to B73, LH185, and LH202 inbreds (40 g kg-1 oil concentration) to a total of 18 testcrosses. Two field experiments were used to evaluate selection in AE and UHO testcrosses. The study showed selection using inbred tester B73 in AE and UHO was effective in increasing grain yield of AE testcrosses without changing (i.e. decreasing) oil and protein concentrations. AE testcrosses produced higher grain yield and greater selection response for grain yield than UHO testcrosses. LH185 was best for grain yield in AE and UHO testcrosses. Increase in grain yield in most of the testcrosses was associated with increases in starch concentration, kernel weight, kernel number, and grain weight
Suppression of Giant Magnetoresistance by a superconducting contact
We predict that current perpendicular to the plane (CPP) giant
magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed
when one of the contacts is superconducting. This is a consequence of a
superconductivity-induced magneto-resistive (SMR) effect, whereby the
conductance of the ferromagnetically aligned state is drastically reduced by
superconductivity. To demonstrate this effect, we compute the GMR ratio of
clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd
tight binding Hamiltonian. By analyzing a simpler model with two orbitals per
site, we also show that the suppression survives in the presence of elastic
scattering by impurities.Comment: 5 pages, 4 figures. Submitted to PR
Comparison of commercial diagnostic tests for Helicobacter pylori antibodies
A number of serological tests measuring the presence of Helicobacter pylori-specific serum immunoglobulin G (IgG) are now commercially available. The aim of this study was to evaluate the clinical accuracy of five commercial H. pylori antibody tests: GAP-IgG (Biomerica), HELpTEST (AMRAD, Kew, Victoria, Australia), HELICO-G (Porton Cambridge), Pyloriset (Orion Diagnostica), and ROCHE (Roche Diagnostics). A total of 162 subjects presenting for routine upper endoscopy were studied. H. pylori was diagnosed if culture, histology, or both were positive. Ten milliliters of venous blood was collected at the time of endoscopy for serological assessment. The sensitivity and specificity of each test (GAP-IgG, HELpTEST, HELICO-G, Pyloriset, and ROCHE) were as follows: 83 and 79%, 92 and 77%, 86 and 65%, 89 and 56%, and 98 and 69%, respectively. Positive and negative predictive values were 97 and 83%, 90 and 91%, 76 and 83%, 68 and 84%, and 86 and 97%, respectively. The specificity of most tests increased by approximately 10% when sera from subjects less than 45 years old were examined. The number of sera falling into the grey zone for each test (an indeterminate result with respect to H. pylori status) varied between 2.5 and 19%. This study highlights the need for all serological kits to be independently evaluated on the population to be studied by testing against a microbiologically defined panel of H. pylori-positive and -negative sera
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