404 research outputs found
Microalbuminuria in relation to the metabolic syndrome and its components in a Chinese population
Comfort-driven disparity adjustment for stereoscopic video
Pixel disparity—the offset of corresponding pixels between left and right views—is a crucial parameter in stereoscopic three-dimensional (S3D) video, as it determines the depth perceived by the human visual system (HVS). Unsuitable pixel disparity distribution throughout an S3D video may lead to visual discomfort. We present a unified and extensible stereoscopic video disparity adjustment framework which improves the viewing experience for an S3D video by keeping the perceived 3D appearance as unchanged as possible while minimizing discomfort. We first analyse disparity and motion attributes of S3D video in general, then derive a wide-ranging visual discomfort metric from existing perceptual comfort models. An objective function based on this metric is used as the basis of a hierarchical optimisation method to find a disparity mapping function for each input video frame. Warping-based disparity manipulation is then applied to the input video to generate the output video, using the desired disparity mappings as constraints. Our comfort metric takes into account disparity range, motion, and stereoscopic window violation; the framework could easily be extended to use further visual comfort models. We demonstrate the power of our approach using both animated cartoons and real S3D videos
A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. IV. Spectral Lag and its Relation to E p Evolution
The spectral evolution and spectral lag behavior of 92 bright pulses from 84 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor (GBM) telescope are studied. These pulses can be classified into hard-to-soft pulses (H2S; 64/92), H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We focus on the relationship between spectral evolution and spectral lags of H2S and H2S-dominated-tracking pulses. The main trend of spectral evolution (lag behavior) is estimated with ( ), where E p is the peak photon energy in the radiation spectrum, t + t 0 is the observer time relative to the beginning of pulse −t 0, and is the spectral lag of photons with energy E with respect to the energy band 8–25 keV. For H2S and H2S-dominated-tracking pulses, a weak correlation between and k E is found, where W is the pulse width. We also study the spectral lag behavior with peak time of pulses for 30 well-shaped pulses and estimate the main trend of the spectral lag behavior with . It is found that is correlated with k E . We perform simulations under a phenomenological model of spectral evolution, and find that these correlations are reproduced. We then conclude that spectral lags are closely related to spectral evolution within the pulse. The most natural explanation of these observations is that the emission is from the electrons in the same fluid unit at an emission site moving away from the central engine, as expected in the models invoking magnetic dissipation in a moderately high-σ outflow
A comprehensive analysis of Fermi Gamma-Ray Burst Data: IV. Spectral lag and Its Relation to Ep Evolution
The spectral evolution and spectral lag behavior of 92 bright pulses from 84
gamma-ray bursts (GRBs) observed by the Fermi GBM telescope are studied. These
pulses can be classified into hard-to-soft pulses (H2S, 64/92),
H2S-dominated-tracking pulses (21/92), and other tracking pulses (7/92). We
focus on the relationship between spectral evolution and spectral lags of H2S
and H2S-dominated-tracking pulses. %in hard-to-soft pulses (H2S, 64/92) and
H2S-dominating-tracking (21/92) pulses. The main trend of spectral evolution
(lag behavior) is estimated with
(), where is the peak photon
energy in the radiation spectrum, is the observer time relative to the
beginning of pulse , and is the spectral lag of photons
with energy with respect to the energy band - keV. For H2S and
H2S-dominated-tracking pulses, a weak correlation between
and is found, where is the pulse width. We also study the spectral
lag behavior with peak time of pulses for 30 well-shaped pulses
and estimate the main trend of the spectral lag behavior with . It is found that is correlated with
. We perform simulations under a phenomenological model of spectral
evolution, and find that these correlations are reproduced. We then conclude
that spectral lags are closely related to spectral evolution within the pulse.
The most natural explanation of these observations is that the emission is from
the electrons in the same fluid unit at an emission site moving away from the
central engine, as expected in the models invoking magnetic dissipation in a
moderately-high- outflow.Comment: 58 pages, 11 figures, 3 tables. ApJ in pres
Chiral Separation of D,L-Mandelic Acid Using An Enantioselective Membrane Formed by Polycondensation of β-Cyclodextrin with 1,6-Diisocyanatohexane on A Polysulfone Membrane
An enantioselective composite membrane was prepared by polycondensation between β-cyclodextrin (β-CD) on a polysulfone support (PS) and a heptane solution of 1,6-diisocyanatohexane (1,6-DCH). The flux and permselective properties of the composite membrane were studied using an aqueous solution of D,L-mandelic acid as the feed solution. The influences of a number of parameters, such as the air-drying time of the β-CD solution on PS, the time of polymerization, the operating pressure and the feed concentration of the racemate, were studied. Chemical characterization was carried out using Fourier transform infrared spectroscopy and the top surface/cross-section was analyzed by scanning electron microscopy. The results showed that when using the enantioselective composite membrane for the optical resolution of the D,L-mandelic acid racemic mixture, an enantiomeric excess of over 85% could be obtained. The paper thus details, for the first time, how a poly(β-CD crosslinked with 1,6-DCH)/PS composite membrane can be used as an optical resolution membrane material to isolate the optical isomers of D,L-mandelic acid
Experimental study of THGEM detector with mini-rim
The gas gain and energy resolution of single and double THGEM detectors
(5{\times}5cm2 effective area) with mini-rims (rim is less than 10{\mu}m) were
studied. The maximum gain can reach 5{\times}103 and 2{\times}105 for single
and double THGEM respectively, while the energy resolution of 5.9 keV X-ray
varied from 18% to 28% for both single and double THGEM detectors of different
hole sizes and thicknesses.All the experiments were investigated in mixture of
noble gases(argon,neon) and small content of other gases(iso-butane,methane) at
atmospheric pressure.Comment: 4pages,6figures, it has been submitted to Chinese Physics
Origin of the large differences in high-pressure stability and superconductivity between ThH9 and ThH18
Recently, the thorium hydride ThH9 possessing an H-rich clathrate structure
has been experimentally synthesized to exhibit a superconducting transition
temperature Tc of 146 K at 170-175 GPa, while the more H-rich clathrate thorium
hydride ThH18 was theoretically predicted to reach a Tc of 296 K at 400 GPa.
Using first-principles calculations, we find that ThH9 has a more ionic
character between Th atoms and H cages than ThH18 and that the latter has a
more substantial hybridization of the Th 6p semicore and H 1s states than the
former. These different bonding characteristics of ThH9 and ThH18 are
associated with their stability at very different pressures. Furthermore, we
reveal that (i) the H-derived density of states at the Fermi level Ef is about
two times larger in ThH18 than in ThH9. (ii) the average squared phonon
frequency of H atoms is about 29% higher in ThH18 than in ThH9, and (iii) the
Fermi surface average squared electron-phonon matrix element is similar between
the two hydrides. Consequently, the electron-phonon coupling constant of ThH18
becomes much greater than that of ThH9, leading to a significant Tc difference
between the two thorium hydrides. Our findings not only provide an explanation
for the very large differences in the stabilization pressure and
superconducting transition temperature between ThH9 and ThH18 but also have
important implications for the design of H-rich, high-Tc clathrate metal
hydrides
{5,10,15,20-Tetrakis[4-(octyloxy)phenyl]porphyrinato}copper(II)
In the title compound, [Cu(C76H92N4O4)], the central Cu(II) ion is situated on an inversion centre. The porphyrinate core exhibits a nearly planar conformation [maximum deviation = 0.027 (3) Å], with Cu—N distances of 1.997 (2) and 2.001 (2) Å. The benzene rings of the 4-octyloxyphenyl groups are rotated at angles of 84.02 (8) and 77.02 (6)° with respect to the mean plane of the porphyrin fragment. The two terminal C atoms in the octyl group are disordered over two positions of equal occupancy
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