16,572 research outputs found
Convergence of Adaptive Finite Element Approximations for Nonlinear Eigenvalue Problems
In this paper, we study an adaptive finite element method for a class of a
nonlinear eigenvalue problems that may be of nonconvex energy functional and
consider its applications to quantum chemistry. We prove the convergence of
adaptive finite element approximations and present several numerical examples
of micro-structure of matter calculations that support our theory.Comment: 24 pages, 12 figure
Superconductivity and Phase Diagram in (LiFe)OHFeSeS
A series of (LiFe)OHFeSeS (0 x 1)
samples were successfully synthesized via hydrothermal reaction method and the
phase diagram is established. Magnetic susceptibility suggests that an
antiferromagnetism arising from (LiFe)OH layers coexists with
superconductivity, and the antiferromagnetic transition temperature nearly
remains constant for various S doping levels. In addition, the lattice
parameters of the both a and c axes decrease and the superconducting transition
temperature T is gradually suppressed with the substitution of S for Se,
and eventually superconductivity vanishes at = 0.90. The decrease of T
could be attributed to the effect of chemical pressure induced by the smaller
ionic size of S relative to that of Se, being consistent with the effect of
hydrostatic pressure on (LiFe)OHFeSe. But the detailed
investigation on the relationships between and the crystallographic
facts suggests a very different dependence of on anion height from
the Fe2 layer or -Fe2- angle from those in FeAs-based superconductors.Comment: 6 pages, 6 figure
CUACE/Dust ─ an integrated system of observation and modeling systems for operational dust forecasting in Asia
An integrated sand and dust storm (SDS) forecasting system – CUACE/Dust (Chinese Unified Atmospheric Chemistry Environment for Dust) has been developed, which consists of a comprehensive dust aerosol module with emission, dry/wet depositions and other atmospheric dynamic processes, and a data assimilation system (DAS) using observational data from the CMA (China Meteorological Administration) ground dust monitoring network and retrieved dust information from a Chinese geostationary satellite – FY-2C. This is the first time that a combination of surface network observations and satellite retrievals of the dust aerosol has been successfully used in the real time operational forecasts in East Asia through a DAS. During its application for the operational SDS forecasts in East Asia for spring 2006, this system captured the major 31 SDS episodes observed by both surface and satellite observations. Analysis shows that the seasonal mean threat score (TS) for 0–24 h forecast over the East Asia in spring 2006 increased from 0.22 to 0.31 by using the DAS, a 41% enhancement. The time series of the forecasted dust concentrations for a number of representative stations for the whole spring 2006 were also evaluated against the surface PM<sub>10</sub> monitoring data, showing a very good agreement in terms of the SDS timing and magnitudes near source regions where dust aerosols dominate. This is a summary paper for a special issue of ACP featuring the development and results of the forecasting system
Studies on bioactive peptide from Chinese soft-shelled turtle (Pelodiscus sinensis) with functionalities of ACE inhibition and antioxidation
This paper dealt with a novel anti-hypertensive collagen peptide from Chinese soft-shelled turtle (Pelodiscus sinensis), which was an efficient inhibitor of angiotensin converting enzyme (ACE, EC 3.4.15.1). ACE plays an important physiological role in the regulation of blood pressure by virtue of the rennin angiotensin system. In traditional Chinese medicine, Chinese soft-shelled turtle possesses many health-function properties. This study investigated the effects of Chinese soft-shelled turtle hydrolysate (CTH) on ACE inhibition. The CTH showed limited inhibition effect on ACE with an IC50 value at 280 ± 8 μg/ml, while its graded fraction of molecular weight less than 5000 Da (CTH5K) obtained through membrane ultra filtration exhibited better inhibitory activity (IC50 = 190 ± 5 μg/ml). The antioxidant activity of CTH was also determined by radical scavenging ability. The CTH5K showed higher antioxidant activity. These results indicate that CTH5K possesses potent antihypertensive and antioxidant activity, and provides a bioactive peptide material with potential applications as ingredients in functional foods.Key words: Chinese soft-shelled turtle, collagen peptide, angiotensin converting enzyme inhibitor, antihypertensive, antioxidant
Robust Quantum State Transfer in Random Unpolarized Spin Chains
We propose and analyze a new approach for quantum state transfer between
remote spin qubits. Specifically, we demonstrate that coherent quantum coupling
between remote qubits can be achieved via certain classes of random,
unpolarized (infinite temperature) spin chains. Our method is robust to
coupling strength disorder and does not require manipulation or control over
individual spins. In principle, it can be used to attain perfect state transfer
over arbitrarily long range via purely Hamiltonian evolution and may be
particularly applicable in a solid-state quantum information processor. As an
example, we demonstrate that it can be used to attain strong coherent coupling
between Nitrogen-Vacancy centers separated by micrometer distances at room
temperature. Realistic imperfections and decoherence effects are analyzed.Comment: 4 pages, 2 figures. V2: Modified discussion of disorder, added
references - final version as published in Phys. Rev. Let
Relation between spectral indices and binary fractions in GCs
Context. We study the relation between the known binary fraction and spectral
absorption feature index to judge whether (and potentially which) spectral
absorption feature indices are suitable for determining the binary fraction.
Aims. The determination of the binary fraction is important in studies of
binary star formation, evolutionary population synthesis models, and other
works. The number of binary stars is difficult to determine for nearly all
stellar systems because the individual stars are need to be resolved
photometrically or spectroscopically. By comparison, their integrated spectra
or spectral absorption feature indices are relatively easy to obtain. Results.
We find that the low-resolution (15\,\AA) spectrum is not suitable for this
study and the binary fraction type would affect the results: (>0.5) and
(tot) exhibit better correlations with the spectral absorption
feature index than (tot) and the difference in metallicity would
significantly affect the above relationship. % Finally, to eliminate the
effects of metallicity, age, and dynamical evolution, we only used those GCs
with multiple spectra observed among different regions. % We find that OIII-1,
OIII-2, H, H, H, H, H, Ca4455, C4668, and TiO indices have strong
correlations with binary fraction. % The two OIII indices are the most
sensitive to the binary fraction, followed by four Balmer indices -- the two
narrower central bandpass Balmer indices (20\AA, F-definition) are more
sensitive than the wider two (40\AA, A-definition) and, lastly, the
Ca4455, C4668, and TiO indices.Comment: 19 pages, 8 figure
A distributed anomaly detection system for in-vehicle network using HTM
With the development of 5G and Internet of Vehicles technology, the possibility of remote wireless attack on an in-vehicle network has been proven by security researchers. Anomaly detection technology can effectively alleviate the security threat, as the first line of security defense. Based on this, this paper proposes a distributed anomaly detection system using hierarchical temporal memory (HTM) to enhance the security of a vehicular controller area network bus. The HTM model can predict the flow data in real time, which depends on the state of the previous learning. In addition, we improved the abnormal score mechanism to evaluate the prediction. We manually synthesized field modification and replay attack in data field. Compared with recurrent neural networks and hidden Markov model detection models, the results show that the distributed anomaly detection system based on HTM networks achieves better performance in the area under receiver operating characteristic curve score, precision, and recall
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