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Search Results: 1 - 10 of 28950 matches for " Jianmin Sun "
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Cooperativity Can Enhance Cellular Signal Detection
Jianmin Sun,Michael Grabe
Quantitative Biology , 2014,
Abstract: Most sensory cells use surface receptors to detect environmental stimuli and initiate downstream signaling. Cooperative interactions among sensory receptors is known to play a crucial role in enhancing the sensitivity of biochemical processes such as oxygen sensing by hemoglobin, but whether cooperativity enhances the fidelity with which a system with multiple receptors can accurately and quickly detect a signal is poorly understood. We model the kinetics of small clusters of receptors in the presence of ligand, where the receptors act independently or cooperatively. We show that the interaction strength and how it is coupled to the dynamics influences the macroscopic observables. Contrary to recent reports, our analysis shows that receptor cooperativity can increase the signal-to-noise ratio, but this increase depends on the underlying dynamics of the signaling receptor cluster.
Active Smoking and Risk of Metabolic Syndrome: A Meta-Analysis of Prospective Studies
Kan Sun, Jianmin Liu, Guang Ning
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047791
Abstract: Background Epidemiological evidence suggests that smoking has been associated with emergence of metabolic syndrome. However, data on this issue are inconsistent and controversial. We therefore conducted a meta-analysis to examine the association between smoking and metabolic syndrome. Methodology and Principal Findings We searched the Medline, Embase and the Cochrane Library database up to March 2012 to identify prospective cohort studies related to smoking and metabolic syndrome. Reference lists of retrieved articles were also reviewed. Summary effect estimates were derived using a random-effects model and stratified by gender, smoking dose, follow-up duration and geographical area. Primary analysis of 13 studies involving 56,691 participants and 8,688 cases detected a significant positive association between active smoking and risk of metabolic syndrome (pooled relative risk [RR] 1.26, 95% CI: 1.10–1.44). Estimates of effects were substantially consistent in the stratified analyses. In the dose-response analysis, risk of metabolic syndrome was stronger for active male smokers (pooled RR 1.34, 95% CI: 1.20–1.50) than it was for former male smokers (pooled RR 1.19, 95% CI: 1.00–1.42), and greater for heavy smokers (pooled RR 1.42, 95% CI: 1.27–1.59) compared with light smokers (pooled RR 1.10, 95% CI: 0.90–1.35). No evidence of statistical publication bias was found (Egger' s test P = 0.227, Begg' s test P = 0.113). Conclusions Active smoking is associated with development of metabolic syndrome. Smoking cessation appears to reduce the risk of metabolic syndrome.
The neighbor list algorithm for a parallelepiped box in molecular dynamics simulations
ZhiWei Cui,Yi Sun,JianMin Qu
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0197-0
Abstract: In classic molecular dynamics (MD) simulations, the conventional Verlet table, cell linked list and many other techniques have been adopted to increase the computational efficiency. However, these methods are only applicable in cubic systems. In this work, the above techniques along with the metric-tensor method are extended to handle NP ensembles, so that MD simulations can be carried out under the most general loading conditions. In order to do so, a particular spatial Cartesian reference frame is proposed to determine the scaling matrix. Also, a combination method, taking the advantages of the improved Verlet table and cell linked list, is established to identify the neighbor atoms very quickly in a parallelepiped box. An example using Lennard-Jones potential is presented to verify the validity of the proposed algorithm.
Influence of air masses on particle number concentration and size distribution at Mt. Waliguan, Qinghai Province, China

MingJin Zhan,JunYing Sun,JianMin Yin,

寒旱区科学 , 2011,
Abstract:
The neighbor list algorithm for a parallelepiped box in molecular dynamics simulations

ZhiWei Cui,Yi Sun,JianMin Qu,

科学通报(英文版) , 2009,
Abstract: In classic molecular dynamics (MD) simulations, the conventional Verlet table, cell linked list and many other techniques have been adopted to increase the computational efficiency. However, these methods are only applicable in cubic systems. In this work, the above techniques along with the metric-tensor method are extended to handle NP ensembles, so that MD simulations can be carried out under the most general loading conditions. In order to do so, a particular spatial Cartesian reference frame is proposed to determine the scaling matrix. Also, a combination method, taking the advantages of the improved Verlet table and cell linked list, is established to identify the neighbor atoms very quickly in a parallelepiped box. An example using Lennard-Jones potential is presented to verify the validity of the proposed algorithm. Supported by the National Natural Science Foundation of China (Grant No. 10472028) and Excellent Youth Foundation of Heilongjiang Province
Effective Magnetic Fields in Graphene Superlattices
Jianmin Sun,H. A. Fertig,L. Brey
Physics , 2010, DOI: 10.1103/PhysRevLett.105.156801
Abstract: We demonstrate that the electronic spectrum of graphene in a one-dimensional periodic potential will develop a Landau level spectrum when the potential magnitude varies slowly in space. The effect is related to extra Dirac points generated by the potential whose positions are sensitive to its magnitude. We develop an effective theory that exploits a chiral symmetry in the Dirac Hamiltonian description with a superlattice potential, to show that the low energy theory contains an effective magnetic field. Numerical diagonalization of the Dirac equation confirms the presence of Landau levels. Possible consequences for transport are discussed.
Spin-orbital effects in magnetized quantum wires and spin chains
Suhas Gangadharaiah,Jianmin Sun,Oleg A. Starykh
Physics , 2007, DOI: 10.1103/PhysRevB.78.054436
Abstract: We present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbital interaction. We show that an interesting interplay of Zeeman and spin-orbit terms, facilitated by the electron-electron interaction, results in the spin-density wave (SDW) state when the magnetic field and spin-orbit axes are orthogonal. We show that this instability is enhanced in a closely related problem of Heisenberg spin chain with asymmetric uniform Dzyaloshinskii-Moriya (DM) interaction. Magnetic field in the direction perpendicular to the DM anisotropy axis results in staggered long-range magnetic order along the orthogonal to the applied field direction. We explore consequences of the uniform DM interaction for the electron spin resonance (ESR) measurements, and point out that they provide way to probe right- and left-moving excitations of the spin chain separately.
Spin-orbit mediated anisotropic spin interaction in interacting electron systems
Suhas Gangadharaiah,Jianmin Sun,Oleg A. Starykh
Physics , 2007, DOI: 10.1103/PhysRevLett.100.156402
Abstract: We investigate interactions between spins of strongly correlated electrons subject to the spin-orbit interaction. Our main finding is that of a novel, spin-orbit mediated anisotropic spin-spin coupling of the van der Waals type. Unlike the standard exchange, this interaction does not require the wave functions to overlap. We argue that this ferromagnetic interaction is important in the Wigner crystal state where the exchange processes are severely suppressed. We also comment on the anisotropy of the exchange between spins mediated by the spin-orbital coupling.
Spin-orbit induced spin-density wave in a quantum wire
Jianmin Sun,Suhas Gangadharaiah,Oleg A. Starykh
Physics , 2006, DOI: 10.1103/PhysRevLett.98.126408
Abstract: We present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbit interaction. We show that an interesting interplay of Zeeman and spin-orbit terms, facilitated by the electron-electron interaction, results in the spin-density wave (SDW) state when the magnetic field and spin-orbit axes are orthogonal. This strongly affects charge transport through the wire: with SDW stabilized, single particle backscattering off an nonmagnetic impurity becomes irrelevant. Sensitivity of the effect to the direction of the magnetic field can be used for experimental verification of this proposal.
A Phenomenological Model for Prediction Auto-Ignition and Soot Formation of Turbulent Diffusion Combustion in a High Pressure Common Rail Diesel Engine
Yongfeng Liu,Jianwei Yang,Jianmin Sun,Aihua Zhu,Qinghui Zhou
Energies , 2011, DOI: 10.3390/en4060894
Abstract: A new phenomenological model, the TP (Temperature Phase) model, is presented to carry out optimization calculations for turbulent diffusion combustion in a high-pressure common rail diesel engine. Temperature is the most important parameter in the TP model, which includes two parts: an auto-ignition and a soot model. In the auto-ignition phase, different reaction mechanisms are built for different zones. For the soot model, different methods are used for different temperatures. The TP model is then implemented in KIVA code instead of original model to carry out optimization. The results of cylinder pressures, the corresponding heat release rates, and soot with variation of injection time, variation of rail pressure and variation of speed among TP model, KIVA standard model and experimental data are analyzed. The results indicate that the TP model can carry out optimization and CFD (computational fluid dynamics) and can be a useful tool to study turbulent diffusion combustion.
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