1,786 research outputs found
On the valence bond solid in the presence of Dzyaloshinskii-Moriya interaction
We examine the stability of the valence bond solid (VBS) phase against the
Dzyaloshinskii-Moriya (DM) interaction in the bipartite lattice. Despite the
VBS is vulnerable against the antiferromagnetic interaction, for example in the
Q-J model proposed by Sandvik, where the quantum phase transition occurs at
, we found that on the contrary the VBS is very stable against
the DM interaction. The quantum phase transition does not occur until D/Q goes
to infinity, where D is the strength of the DM interaction. The VBS in the ALKT
model and the Haldane gap system also exhibit the same property.Comment: 5 pages and 5 figure
Independent director interlocks: effects and boundary on the earnings persistence of the firm
This article first analyses the impact of independent director interlocks on firmsâ earnings persistence in China, an emerging market
from 2007 to 2017. Using the independent director network data
and the unique internal control index, this article investigates the
association between independent director interlocks and earnings
persistence, and the roles of firmsâ outside director interlocks and
firmsâ inside internal control playing in earnings persistence. Our
results reveal a significant and positive association between independent director interlocks and earnings persistence, and in the
context, there is a clear mediation effect of internal control in
relationship of independent director interlocks and earnings persistence. Further analyses on the scope and stability of independent director interlocks effects show that independent director
interlocks can both improve accrual earnings persistence and
cash flow persistence. Meanwhile, the effect of independent director interlocks differentiates under the influence of firmsâ strategy, only playing a significant role in defensive ones. Moreover,
we find that independent director interlocks can relieve the
âaccrual anomaliesâ in the securities market. Our results are robust
to the various measure of earnings persistence and alternative
methodological techniques
Detecting non-Markovian plasmonic band gaps in quantum dots using electron transport
Placing a quantum dot close to a metal nanowire leads to drastic changes in
its radiative decay behavior because of evanescent couplings to surface
plasmons. We show how two non-Markovian effects, band-edge and retardation,
could be observed in such a system. Combined with a quantum dot p-i-n junction,
these effects could be readout via current-noise measurements. We also discuss
how these effects can occur in similar systems with restricted geometries, like
phononic cavities and photonic crystal waveguides. This work links two
previously separate topics: surface-plasmons and current-noise measurements.Comment: 8 page
Spin structure factor and thermodynamics in the antiferromagnetic quantum Ising model in the pyrochlore lattice
We numerically compute the temperature dependence of spin structure factor
and thermodynamic quantities in the antiferromagnetic quantum Ising model in
the pyrochlore lattice. This model exhibits spin disorder ground state with
exponentially-decayed spin correlation. We reproduce the temperature dependence
of the pinch point structure in the neutron scattering experiment and correct
entropy obtained from the measurement of the specific heat.Comment: 6 pages, 7 figure
Dynamics similarity design and verification of rotor system
In order to study the dynamics similarity of original model similar to normal model, the similarity criteria and the similarity ratio of the normal and original models for the rotor system were derived by the dimension analysis method. ANSYS was used to numerically calculate the critical speeds, modal shapes and harmonic response of the original and normal models of rotor system. The analysis results show that, for the rotor system, the dynamic characteristics of the normal and original models satisfy the requirement of the similarity criteria perfectly. The dynamic characteristics of the original model can be predicted accurately by the corresponding normal model
Dynamic characteristics of aero-engineâs rotor under large maneuvering flight
In view of the large maneuvering overload of the rotor system in Unmanned Aerial Vehicle (UAV), the dynamic characteristics of rotor system under large maneuvering overload conditions were analyzed in this paper. The finite element model of rotor system under large maneuvering overload was first established by Timoshenko beam element theory and finite element method. The motion differential equations of the rotor system were derived by Lagrange equation, and the additional damping matrix, stiffness matrix and excitation force were obtained. Critical speeds and unbalance response were calculated by characteristic equation method and Newmark-β numerical integration method respectively. The calculation results showed that the additional damping and stiffness leaded the critical speeds of the rotor system to change under large maneuvering flight, and the additional excitation force resulted in a certain static displacement of the whirling orbits
Research on the dynamic characteristics of the squeeze film damper of a certain aero-engine
Numerical methods were conducted to simulate the characteristics of SFD under different clearance, eccentricity and precession angular velocity and verified by bidirectional excitation experiments, which is comparatively leading initiative in characteristic measurement of SFD. In addition, finite difference method was introduced to derive Reynolds equation and SOR method to obtain the distribution of oil film, the convergence was also mathematical proof. The results indicate the rotor system keep large vibration state for a long time due to the increasing of actual critical speed of system, which result from the oil film stiffness increases nonlinear excessively with the increase of eccentricity; clearance make a great influence on SFD, especially SFD with large radial size should be kept within 2Â â°
Single-nucleotide polymorphisms and haplotype of CYP2E1 gene associated with systemic lupus erythematosus in Chinese population
Introduction: Cytochrome P-450 2E1 (CYP2E1) is an important member of the CYP superfamily, which is involved in the metabolism and activation of many low molecular weight toxic compounds. We tried to investigate the possible association of CYP2E1 tag single nucleotide polymorphisms (SNPs) with susceptibility to systemic lupus erythematosus (SLE) in a Chinese Han population. Methods: The coding and flanking regions of the CYP2E1 gene were scanned for polymorphisms and tag SNPs were selected. A two-stage case-control study was performed to genotype a total of 876 SLE patients and 680 geographically matched healthy controls (265 cases and 288 controls in stage I and 611 cases and 392 controls in stage II). SLE associations of alleles, genotypes and haplotypes were tested by age and sex adjusted logistic regression. The gene transcription quantitation was carried out for peripheral blood mononuclear cell (PBMC) samples from 120 healthy controls. Results: Tag SNP rs2480256 was found significantly associated with SLE in both stages of the study. The "A" allele was associated with slightly higher risk (odds ratio (OR) = 1.165, 95% confidence interval (CI) 1.073 to 1.265, P = 2.75E-4) and "A/A" genotype carriers were with even higher SLE risk (OR = 1.464 95% CI 1.259 to 1.702, P = 7.48E-7). When combined with another tag SNP rs8192772, we identified haplotype "rs8192772-rs2480256/TA" over presented in SLE patients (OR 1.407, 95% CI 1.182 to 1.675, P = 0.0001) and haplotype "TG" over presented in the controls (OR 0.771, 95% CI 0.667 to 0.890, P = 0.0004). The gene transcription quantitation analysis further proved the dominant effect of rs2480256 as the "A/A" genotype showed highest transcription. Conclusions: Our results suggest the involvement of CYP2E1 as a susceptibility gene for SLE in the Chinese population
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