5,862 research outputs found
On "the authentic damping mechanism" of the phonon damping model
Some general features of the phonon damping model are presented. It is
concluded that the fits performed within this model have no physical content
Density Regression Based on Proportional Hazards Family
This paper develops a class of density regression models based on proportional hazards family, namely, Gamma transformation proportional hazard (Gt-PH) model . Exact inference for the regression parameters and hazard ratio is derived. These estimators enjoy some good properties such as unbiased estimation, which may not be shared by other inference methods such as maximum likelihood estimate (MLE). Generalised confidence interval and hypothesis testing for regression parameters are also provided. The method itself is easy to implement in practice. The regression method is also extended to Lasso-based variable selection.National Natural Science Foundation of China (Grant No. 71490725, 71071087 and 11261048
Magnetic susceptibility of alkali-TCNQ salts and extended Hubbard models with bond order and charge density wave phases
The molar spin susceptibilities of Na-TCNQ, K-TCNQ and Rb-TCNQ(II)
are fit quantitatively to 450 K in terms of half-filled bands of three
one-dimensional Hubbard models with extended interactions using exact results
for finite systems. All three models have bond order wave (BOW) and charge
density wave (CDW) phases with boundary for nearest-neighbor
interaction and on-site repulsion . At high , all three salts have
regular stacks of anion radicals. The fits place Na and
K in the CDW phase and Rb(II) in the BOW phase with . The Na and
K salts have dimerized stacks at while Rb(II) has regular stacks at
100K. The analysis extends to dimerized stacks and to dimerization
fluctuations in Rb(II). The three models yield consistent values of ,
and transfer integrals for closely related stacks. Model
parameters based on are smaller than those from optical data that in
turn are considerably reduced by electronic polarization from quantum chemical
calculation of , and on adjacent ions. The
analysis shows that fully relaxed states have reduced model parameters compared
to optical or vibration spectra of dimerized or regular stacks.Comment: 9 pages and 5 figure
Analysis of two pheromone-responsive conjugative multiresistance plasmids carrying the novel mobile optrA locus from Enterococcus faecalis
Background: The acquired optrA gene, which encodes a ribosomal protection protein of the ABC-F family, can confer cross-resistance to linezolid and florfenicol, posing a serious therapeutic challenge to both human and veterinary medicine.
Purpose: The objective of this study was to investigate the two Enterococcus faecalis (E. faecalis) plasmids for their fine structure, their transferability and the presence of mobile antimicrobial resistance loci.
Methods: To elucidate their fine structure, the two plasmids were completely sequenced and the sequences analysed. Besides conjugation experiments, inverse PCR assays were conducted to see whether minicircles are produced from the mobile antimicrobial resistance loci.
Results: Two pheromone-responsive conjugative optrA-carrying plasmids from E. faecalis, pE211 and pE508 were identified, which can transfer with frequencies of 2.6 ×10−2 and 3.7 ×10−2 (transconjugant per donor), respectively. In both plasmids, optrA was located on the novel mobile optrA locus with different sizes (12,834 bp in pE211 and 7,561 bp in pE508, respectively), flanked by two copies of IS1216 genes in the same orientation. Inverse PCR revealed that circular forms can be generated, consisting of optrA and one copy of IS1216, indicating they are all active. The 77,562 bp plasmid pE211 also carried Tn558 and a mobile bcrABDR locus, and the 84,468 bp plasmid pE508 also harbored the genes fexA, tet(L), tet(O/W/32/O) and a mobile aac(A)-aph(D) locus.
Conclusion: The presence of mobile genetic elements in these plasmids renders them flexible and these elements will aid to the persistence and dissemination of these plasmids among enterococci and potentially also other gram-positive bacteria
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Dynamics of long-range order in an exciton-polariton condensate
We report on time resolved measurements of the first order spatial coherence
in an exciton polariton Bose-Einstein condensate. Long range spatial coherence
is found to set in right at the onset of stimulated scattering, on a picosecond
time scale. The coherence reaches its maximum value after the population and
decays slower, staying up to a few hundreds of picoseconds. This behavior can
be qualitatively reproduced, using a stochastic classical field model
describing interaction between the polariton condensate and the exciton
reservoir within a disordered potential.Comment: 7 pages, 4 figure
Dichlorido(2,9-dipropÂoxy-1,10-phenanthroline-κ2 N,N′)cadmium(II)
In the title complex, [CdCl2(C18H20N2O2)], the CdII ion is coordinated by two N atoms from a bis-chelating 2,9-dipropÂoxy-1,10-phenanthroline ligand and two Cl atoms in a distorted tetraÂhedral environment. The two Cd—Cl bond distances are significantly different from each other and the N—Cd—N bond angle is acute. In the crystal structure, there are π–π stacking interÂactions between symmetry-related phenanthroline ring systems, with a centroid–centroid distance of 3.585 (3) Å
CFD Simulation of Temperature Field Distribution of the Liquefied Hydrocarbon Spherical Tank Leaking
AbstractLiquefied hydrocarbon is normally stored under high pressure in overheating state in the spherical tank. Once leakage occurs, the liquefied hydrocarbon will quickly gasify and absorb a great deal of heat, making temperature of spherical tank decrease sharply. In order to investigate this process, physical model was established, and the Reynolds time averaged Navier-Stokes equation and k-ɛ turbulent model as the CFD simulation method were used in this study. The temperature distribution of the spherical tank and the environment after spherical tank pipeline leaking was analyzed. The influences of leakage location and leak area on the spherical tank temperature distribution were analyzed, and a meaningful conclusion was obtained. This study could provide theoretical basis and technical support for the safety control of liquefied hydrocarbon spherical tank leakage. © 2012 Published by Elsevier Ltd. Selection and/or peer-review (pre-review) under responsibility of the Capital University of Economics and Business, China Academy of Safety Science and Technology
Multi-view Multi-label Anomaly Network Traffic Classification based on MLP-Mixer Neural Network
Network traffic classification is the basis of many network security
applications and has attracted enough attention in the field of cyberspace
security. Existing network traffic classification based on convolutional neural
networks (CNNs) often emphasizes local patterns of traffic data while ignoring
global information associations. In this paper, we propose a MLP-Mixer based
multi-view multi-label neural network for network traffic classification.
Compared with the existing CNN-based methods, our method adopts the MLP-Mixer
structure, which is more in line with the structure of the packet than the
conventional convolution operation. In our method, the packet is divided into
the packet header and the packet body, together with the flow features of the
packet as input from different views. We utilize a multi-label setting to learn
different scenarios simultaneously to improve the classification performance by
exploiting the correlations between different scenarios. Taking advantage of
the above characteristics, we propose an end-to-end network traffic
classification method. We conduct experiments on three public datasets, and the
experimental results show that our method can achieve superior performance.Comment: 15 pages,6 figure
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