1,347 research outputs found
Performance of RF MEMS switches at low temperatures
The actuation voltage of microelectromechanical system (MEMS) \ud
metal switches was investigated at temperatures ranging from 10 to 290 K. The investigation shows a 50% increase in the actuation voltage at low temperature. A comparison has been made using a published model and showed similar increment of actuation voltage at low temperature
Effects of exercise vs experimental osteoarthritis on imaging outcomes
SummaryObjectiveTo identify changes in imaging outcomes in a controlled model of osteoarthritis (OA) vs exercise.MethodSixteen 2-year-old horses were randomly assigned to an exercise control (n=8) or an exercise OA (n=8) group. All horses had middle carpal joints arthroscopically explored and an osteochondral fragment was induced in one middle carpal joint of the OA group. All horses were treadmill exercised for the duration of the study (91 days). Clinical, radiographic, nuclear scintigraphic, computed tomographic and magnetic resonance imaging (MRI) examinations were performed and outcomes of these were compared between groups. Imaging results were correlated to clinical, biomarker and gross pathologic results.ResultsThe OA group had significant increases in clinical outcomes and most imaging parameters. Specifically, the OA group showed significant increases in radiographic lysis and nuclear scintigraphic uptake. There was very little change in subchondral bone density, but a significant change in subchondral bone edema. Radiographic lysis, radial carpal bone edema and nuclear scintigraphy were strongly correlated with clinical changes and radial carpal bone edema was strongly correlated with changes in Type I and Type II collagen found in the synovial fluid.ConclusionsOA induced significant changes in imaging parameters beyond the adaptation seen with exercise. Bone edema detected with MRI was closely correlated with collagen biomarkers detected in the synovial fluid
Length-weight relationships of bivalves from coastal waters of Korea
Parameters a and b of the length (L)-weight (W) relationship W = a · Lb are presented for 17 commercial bivalve species collected from the southwest coastal waters of Korea. Estimates of b varied between 2.44 (Atrina pinnata japonica) and 3.31 (Scaphara broughtonii) with a mean of 2.891 (± 0.212). A total of 2 107 specimens were analyzed for this study. The length-weight relationship was isometric in most of the species
Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube
We have studied the afterpulse of a hemispherical photomultiplier tube for an
upcoming reactor neutrino experiment. The timing, the amplitude, and the rate
of the afterpulse for a 10 inch photomultiplier tube were measured with a 400
MHz FADC up to 16 \ms time window after the initial signal generated by an LED
light pulse. The time and amplitude correlation of the afterpulse shows several
distinctive groups. We describe the dependencies of the afterpulse on the
applied high voltage and the amplitude of the main light pulse. The present
data could shed light upon the general mechanism of the afterpulse.Comment: 11 figure
Smectic ordering in liquid crystal - aerosil dispersions I. X-ray scattering
Comprehensive x-ray scattering studies have characterized the smectic
ordering of octylcyanobiphenyl (8CB) confined in the hydrogen-bonded silica
gels formed by aerosil dispersions. For all densities of aerosil and all
measurement temperatures, the correlations remain short range, demonstrating
that the disorder imposed by the gels destroys the nematic (N) to smectic-A
(SmA) transition. The smectic correlation function contains two distinct
contributions. The first has a form identical to that describing the critical
thermal fluctuations in pure 8CB near the N-SmA transition, and this term
displays a temperature dependence at high temperatures similar to that of the
pure liquid crystal. The second term, which is negligible at high temperatures
but dominates at low temperatures, has a shape given by the thermal term
squared and describes the static fluctuations due to random fields induced by
confinement in the gel. The correlation lengths appearing in the thermal and
disorder terms are the same and show strong variation with gel density at low
temperatures. The temperature dependence of the amplitude of the static
fluctuations further suggests that nematic susceptibility become suppressed
with increasing quenched disorder. The results overall are well described by a
mapping of the liquid crystal-aerosil system into a three dimensional XY model
in a random field with disorder strength varying linearly with the aerosil
density.Comment: 14 pages, 13 figure
A Lanczos algorithm for linear response
An iterative algorithm is presented for solving the RPA equations of linear
response. The method optimally computes the energy-weighted moments of the
strength function, allowing one to match the computational effort to the
intrinsic accuracy of the basic mean-field approximation, avoiding the problem
of solving very large matrices. For local interactions, the computational
effort for the method scales with the number of particles N_p as O(N_p^3).Comment: 12 pages including 3 figures; Late
Analytical approach to viscous fingering in a cylindrical Hele-Shaw cell
We report analytical results for the development of the viscous fingering
instability in a cylindrical Hele-Shaw cell of radius a and thickness b. We
derive a generalized version of Darcy's law in such cylindrical background, and
find it recovers the usual Darcy's law for flow in flat, rectangular cells,
with corrections of higher order in b/a. We focus our interest on the influence
of cell's radius of curvature on the instability characteristics. Linear and
slightly nonlinear flow regimes are studied through a mode-coupling analysis.
Our analytical results reveal that linear growth rates and finger competition
are inhibited for increasingly larger radius of curvature. The absence of
tip-splitting events in cylindrical cells is also discussed.Comment: 14 pages, 3 ps figures, Revte
Relationship between transport anisotropy and nematicity in FeSe
We thank the Max Planck Society for financial support. C. W. H., A. P. M., and C. T. acknowledge support by the DFG (DE) through the Collaborative Research Centre SFB 1143 (Projects C09 and A04). C. T. acknowledges support by the DFG (DE) through the Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC 2147). Work in Japan was supported by Grants-in-Aid for Scientific Research (KAKENHI) (No. JP19H00649 and No. JP18H05227), and Grant-in-Aid for Scientific Research on innovative areas “Quantum Liquid Crystals” (No. JP19H05824 and No. JP20H05162) from Japan Society for the Promotion of Science (JSPS).The mechanism behind the nematicity of FeSe is not known. Through elastoresitivity measurements it has been shown to be an electronic instability. However, thus far measurements have extended only to small strains, where the response is linear. Here, we apply large elastic strains to FeSe and perform two types of measurement. (1) Using applied strain to control twinning, the nematic resistive anisotropy at temperatures below the nematic transition temperature Ts is determined. (2) Resistive anisotropy is measured as nematicity is induced through applied strain at fixed temperature above Ts. In both cases, as nematicity strengthens, the resistive anisotropy peaks at about 7%, then decreases. Below ≈40 K, the nematic resistive anisotropy changes sign. We discuss possible implications of this behavior for theories of nematicity. In addition, we report the following. (1) Under experimentally accessible conditions with bulk crystals, stress, rather than strain, is the conjugate field to the nematicity of FeSe. (2) At low temperatures the twin boundary resistance is ∼10% of the sample resistance, and must be properly subtracted to extract intrinsic resistivities. (3) Biaxial in-plane compression increases both in-plane resistivity and the superconducting critical temperature Tc, consistent with a strong role of the yz orbital in the electronic correlations.Publisher PDFPeer reviewe
Toroidal mode number estimation of the edge-localized modes using the KSTAR 3-D electron cyclotron emission imaging system
A new and more accurate technique is presented for determining the toroidal mode number n of edge-localized modes (ELMs) using two independent electron cyclotron emission imaging (ECEI) systems in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The technique involves the measurement of the poloidal spacing between adjacent ELM filaments, and of the pitch angle ?? O of filaments at the plasma outboard midplane. Equilibrium reconstruction verifies that ?? O is nearly constant and thus well-defined at the midplane edge. Estimates of n obtained using two ECEI systems agree well with n measured by the conventional technique employing an array of Mirnov coils.open3
Hydrogen-bonded Silica Gels Dispersed in a Smectic Liquid Crystal: A Random Field XY System
The effect on the nematic to smectic-A transition in octylcyanobiphenyl (8CB)
due to dispersions of hydrogen-bonded silica (aerosil) particles is
characterized with high-resolution x-ray scattering. The particles form weak
gels in 8CB creating a quenched disorder that replaces the transition with the
growth of short range smectic correlations. The correlations include thermal
critical fluctuations that dominate at high temperatures and a second
contribution that quantitatively matches the static fluctuations of a random
field system and becomes important at low temperatures.Comment: 10 pages, 4 postscript figures as separate file
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