5,396 research outputs found
Link between K-absorption edges and thermodynamic properties of warm-dense plasmas established by improved first-principles method
A precise calculation that translates shifts of X-ray K-absorption edges to
variations of thermodynamic properties allows quantitative characterization of
interior thermodynamic properties of warm dense plasmas by X-ray absorption
techniques, which provides essential information for inertial confinement
fusion and other astrophysical applications. We show that this interpretation
can be achieved through an improved first-principles method. Our calculation
shows that the shift of K-edges exhibits selective sensitivity to thermal
parameters and thus would be a suitable temperature index to warm dense
plasmas. We also show with a simple model that the shift of K-edges can be used
to detect inhomogeneity inside warm dense plasmas when combined with other
experimental tools
First-Principles Calculation of Principal Hugoniot and K-Shell X-ray Absorption Spectra for Warm Dense KCl
Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are
calculated using the first-principles molecular dynamics method. Evolution of
electronic structures as well as the influence of the approximate description
of ionization on pressure (caused by the underestimation of the energy gap
between conduction bands and valence bands) in the first-principles method are
illustrated by the calculation. Pressure ionization and thermal smearing are
shown as the major factors to prevent the deviation of pressure from global
accumulation along the Hugoniot. In addition, cancellation between electronic
kinetic pressure and virial pressure further reduces the deviation. The
calculation of X-ray absorption spectra shows that the band gap of KCl persists
after the pressure ionization of the electrons of Cl and K taking place at
lower energy, which provides a detailed understanding to the evolution of
electronic structures of warm dense matter
Postoperative vomiting/nausea in Chinese patients undergoing bariatric surgery
Purpose: To assess the incidence of post-operative vomiting/nausea (PVN), as well as usage and effectiveness of PVN prophylaxis in Chinese patients receiving bariatric surgery.
Methods: This prospective observational study included 82 patients subjected to bariatric surgery using total intravenous (IV) anesthesia. Patients were given PVN prophylactic treatment as per the local practice depending on Apfel et al criterion for simplified risk score useful for PVN prediction. Postsurgery, the patients were evaluated at 2, 4, 6, 24, 48 and 72 h using a questionnaire. Univariate analysis of risk factors associated with PVN was carried conducted with Pearson’s Chi-squared test for category variables and Mann–Whitney–Wilcoxon test for a continuous variable.
Results: About 69 % of the patients developed PVN within 24 h post-surgery, and the risk increased with increase in the number of PVN risk factors. Significant contrasts were seen with respect to PVN, with higher occurrence in females (81.36 %), when compared to males (39.13 %) within the first 24 h (p < 0.05). Two patients got sub-optimum PVN prophylactic therapy as per guidelines, 19 patients had optimum therapy, while 61 patients had supra-optimum therapy. Moreover, 63.94 % of patients who obtained supra-optimum PVN prophylactic therapy experienced PVN within 24 h post-surgery, while 84.21 % of patients with optimum PVN prophylactic therapy experienced PVN within the same period (p < 0.05). Overall, 35.37 % of patients experienced serious nausea 24 h post-surgery.
Conclusion: PVN incidence is high, notwithstanding the fact that almost all the patients received optimum or supra-optimum prophylactic therapy. These findings raise dubiety regarding the viability and significance of using risk-based PVN prophylactic therapy in patients under bariatric surgery. Thus, further research is needed in this regard
N′-(Butan-2-ylidene)furan-2-carbohydrazide
The title Schiff base compound, C9H12N2O2, was obtained from a condensation reaction of butan-2-one and furan-2-carbohydrazide. The furan ring and the hydrazide fragment are roughly planar, the largest deviation from the mean plane being 0.069 (2)Å, but the butanylidene group is twisted slightly with respect to this plane by a dihedral angle of 5.2 (3)°. In the crystal, intermolecular N—H⋯O hydrogen bonds link pairs of inversion-related molecules, forming dimers of R
2
2(8) graph-set motif
100-Gbps per-channel all-optical wavelength conversion without pre-amplifiers based on an integrated nanophotonic platform
All-optical wavelength conversion based on four-wave mixing attracts intense interest in many areas, especially in optical fiber communications, due to the advantages of femtosecond response, modulation-format transparency, and high flexibility in optical network management. In this paper, we present the first optical translation of 32-GBaud 16QAM signals with an integrated Si3N4 nonlinear nanophotonic waveguide. An on-chip continuous-wave conversion efficiency of up to -0.6dB from S band to C band is achieved in the dispersion-engineered low-loss Si3N4 nonlinear waveguide that is back-end compatible with complementary metal-oxide-semiconductor processes. The high conversion efficiency avoids the use of external optical amplifiers for signal demodulation. The converted idler is successfully received with a sensitivity penalty of less than 0.5dB. Moreover, pre-amplifier-free multichannel wavelength conversion of over-100-Gbps coherent signals in C band is also demonstrated using the same Si3N4 nanophotonic waveguide via changing the pump wavelength, which shows good flexibility in all-optical signal processing. Additionally, wavelength conversion with a bandwidth over 100nm can be expected by optimizing the current Si3N4 nanophotonic waveguide, which is promising for commercial coherent fiber communications and has bright prospects in various areas including optical signal processing, imaging, optical spectroscopy, and quantum optics
CP Test in J/Psi -> gamma phi phi Decay
We propose to test CP symmetry in the decay \jp\to \gamma \phi\phi, for
which large data sample exists at BESII, and a data sample of
's will be collected with BESIII and CLEO-C program. We suggest some CP
asymmetries in this decay mode for CP test. Assuming that CP violation is
introduced by the electric- and chromo-dipole moment of charm quark, these CP
asymmetries can be predicted by using valence quark models. Our work shows a
possible way to get information about the electric- and chromo-dipole moment of
charm quark, which is little known. Our results show that with the current data
sample of , electric- and chromo-dipole moment can be probed at order
of . In the near future with a data sample, these
moments can be probed at order of .Comment: Misprints corrected. To appear in Phys. Lett.
Multichannel surface EMG decomposition based on measurement correlation and LMMSE
A method based on measurement correlation (MC) and linear minimum mean square error (LMMSE) for multichannel surface electromyography (sEMG) signal decomposition was developed in this study. This MC-LMMSE method gradually and iteratively increases the correlation between an optimized vector and a reconstructed matrix that is correlated with the measurement matrix. The performance of the proposed MC-LMMSE method was evaluated with both simulated and experimental sEMG signals. Simulation results show that the MC-LMMSE method can successfully reconstruct up to 53 innervation pulse trains with a true positive rate greater than 95%. The performance of the MC-LMMSE method was also evaluated using experimental sEMG signals collected with a 64-channel electrode array from the first dorsal interosseous muscles of three subjects at different contraction levels. A maximum of 16 motor units were successfully extracted from these multichannel experimental sEMG signals. The performance of the MC-LMMSE method was further evaluated with multichannel experimental sEMG data by using the “two sources” method. The large population of common MUs extracted from the two independent subgroups of sEMG signals demonstrates the reliability of the MC-LMMSE method in multichannel sEMG decomposition
Genome-wide Identification, Characterization, and Expression Analysis of PHT1 Phosphate Transporters in Wheat
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