Anomalous Spin Dynamics of Hubbard Model on Honeycomb Lattices

In this paper, the honeycomb Hubbard model in optical lattices is investigated using O(3) non-linear sigma model. A possible quantum non-magnetic insulator in a narrow parameter region is found near the metal-insulator transition. We study the corresponding dynamics of magnetic properties, and find that the narrow region could be widened by hole doping.Comment: 9 pages, 12 figure

Quench dynamics of topological quantum phase transition in Wen-plaquette model

We study the quench dynamics of the topological quantum phase transition in the two-dimensional transverse Wen-plaquette model, which has a phase transition from a Z2 topologically ordered to a spin-polarized state. By mapping the Wen-plaquette model onto a one-dimensional quantum Ising model, we calculate the expectation value of the plaquette operator Fi during a slowly quenching process from a topologically ordered state. A logarithmic scaling law of quench dynamics near the quantum phase transition is found, which is analogous to the well-known static critical behavior of the specific heat in the one-dimensional quantum Ising model.Comment: 8 pages, 5 figures,add new conten

Oil and Gas Air Heaters

Most conventional air heaters adopt indirect heat transfer, which uses combustion gases to indirectly heat fresh air by heating surfaces to generate hot air used for material drying and dehumidification. We call them indirect air heaters. However, they have a higher manufacturing cost and lower thermal efficiency, especially when high temperature air is needed. For this reason, a direct air heater applicable for or feed and industrial raw products is put forward, which has advantages such as less production cost, smaller dimensions and higher thermal efficiency. Their design, working principles, characteristics, structure and applications are presented in this article, and brief comparisons are made between the indirect and direct air heater. Finally, the relation of hot-air temperature, oil or gas consumption and fresh airflow is determined based on energy equilibrium

Coexistence of Itinerant Electrons and Local Moments in Iron-Based Superconductors

In view of the recent experimental facts in the iron-pnictides, we make a proposal that the itinerant electrons and local moments are simultaneously present in such multiband materials. We study a minimal model composed of coupled itinerant electrons and local moments to illustrate how a consistent explanation of the experimental measurements can be obtained in the leading order approximation. In this mean-field approach, the spin-density-wave (SDW) order and superconducting pairing of the itinerant electrons are not directly driven by the Fermi surface nesting, but are mainly induced by their coupling to the local moments. The presence of the local moments as independent degrees of freedom naturally provides strong pairing strength for superconductivity and also explains the normal-state linear-temperature magnetic susceptibility above the SDW transition temperature. We show that this simple model is supported by various anomalous magnetic properties and isotope effect which are in quantitative agreement with experiments.Comment: 7 pages, 4 figures; an expanded versio

Study of color suppressed modes B0→Dˉ(∗)0η(′)B^0 \to \bar D^{(*)0} \eta^{(\prime)}

The color suppressed modes $B^0 \to \bar D^{(*)0} \eta^{(\prime)}$ are analyzed in perturbative QCD approach. We find that the dominant contribution is from the non-factorizable diagrams. The branching ratios calculated in our approach for $B^0 \to \bar D^{(*)0} \eta$ agree with current experiments. By neglecting the gluonic contribution, we predict the branching ratios of $B^0 \to \bar D^{(*)0} \eta'$ are at the comparable size of $B^0 \to \bar D^{(*)0} \pi^0$, but smaller than that of $B^0 \to \bar D^{(*)0} \eta$.Comment: revtex, 5 pages, axodraw.st

Direct CP Violation in Hadronic B Decays

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on $k_T$ factorization, by using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.Comment: 11 pages, 3 figures, revtex4, Talk given at the Workshop on the Frontiers of Theoretical Physics and Cross-Disciplinary, NSFC, Beijing, March 200

Exact results of the mixed-spin Ising model on a decorated square lattice with two different decorating spins of integer magnitudes

The mixed-spin Ising model on a decorated square lattice with two different decorating spins of the integer magnitudes S_B = 1 and S_C = 2 placed on horizontal and vertical bonds of the lattice, respectively, is examined within an exact analytical approach based on the generalized decoration-iteration mapping transformation. Besides the ground-state analysis, finite-temperature properties of the system are also investigated in detail. The most interesting numerical result to emerge from our study relates to a striking critical behaviour of the spontaneously ordered 'quasi-1D' spin system. It was found that this quite remarkable spontaneous order arises when one sub-lattice of the decorating spins (either S_B or S_C) tends towards their 'non-magnetic' spin state S = 0 and the system becomes disordered only upon further single-ion anisotropy strengthening. The effect of single-ion anisotropy upon the temperature dependence of the total and sub-lattice magnetization is also particularly investigated.Comment: 17 pages, 6 figure

927-37 Is Coronary Revascularization Complete Therapy for Secondary Prevention of Ischemic Cardiac Arrest?

Coronary revascularization has been suggested assole therapy for secondary prevention of sudden cardiac arrest associated with ischemia. Among 412 consecutive patients receiving an implantable defibrillator (ICD), 23 (6%) were identified as: sudden cardiac arrest survivors, noninducible with programmed stimulation, unstable angina or ischemia on a functional study, and underwent successful coronary revascularization. In follow-up, 10 (43%) of the 23 patients received ICD shocks (8±8 per patient, range: 1–22) shocks) and 9/10 had syncope/presyncope associated with at least one ICD discharge.Clinical Characteristics:ICD firings (n=10)*No ICD firings (n=13)*Follow-up (months)39±1331±21Age (years)63±763±12Male gender89Mean left ventricular ejection fraction (%)36±1040±14Previous history of a myocardial infarction1010Presence of a left ventricular aneurysm41Q-wave infarction pattern on electrocardiogram75Sudden cardiac arrest presenting with exertion, angina, or CPK elevation88Mean number of vessels with coronary disease2.2±0.823±0.9Mean severity of coronary stenosis (%)87±1888±16Coronary revascularization considered complete710β-blocker therapy55Antiarrhythmic therapy812*p value>0.05No clinical characteristic was statistically different between patients with and without ICD shocks. In conclusion, coronary revascularization alone may be inadequate therapy for survivors of sudden cardiac arrest associated with ischemia who are noninducible with programmed stimulation, and clinical variables cannot predict which patients are likely to experience recurrent malignant ventricular arrhythmias. Therefore, ICD therapy should be considered in these patients

Quantum Non-Magnetic state near Metal-Insulator Transition - a Possible Candidate of Spin Liquid State

In this paper, based on the formulation of an O(3) non-linear sigma model, we study the two-dimensional Pi-flux Hubbard model at half-filling. A quantum non-magnetic insulator is explored near the metal-insulator transition that may be a possible candidate of the spin liquid state. Such quantum non-magnetic insulator on square lattice is not induced by frustrations. Instead, it originates from quantum spin fluctuations with relatively small effective spin moments. In the strong-coupling limit, our results of the spin velocity and spin order parameter agree with results obtained from earlier calculations.Comment: 6 pages, 6 figures, Version of publication in EPL, removing the contents of honeycomb lattice and adding some contents of square lattic