14,141 research outputs found
Quantum transfer matrix method for one-dimensional disordered electronic systems
We develop a novel quantum transfer matrix method to study thermodynamic
properties of one-dimensional (1D) disordered electronic systems. It is shown
that the partition function can be expressed as a product of local
transfer matrices. We demonstrate this method by applying it to the 1D
disordered Anderson model. Thermodynamic quantities of this model are
calculated and discussed.Comment: 7 pages, 10 figure
Entanglement-enhanced measurement of a completely unknown phase
The high-precision interferometric measurement of an unknown phase is the
basis for metrology in many areas of science and technology. Quantum
entanglement provides an increase in sensitivity, but present techniques have
only surpassed the limits of classical interferometry for the measurement of
small variations about a known phase. Here we introduce a technique that
combines entangled states with an adaptive algorithm to precisely estimate a
completely unspecified phase, obtaining more information per photon that is
possible classically. We use the technique to make the first ab initio
entanglement-enhanced optical phase measurement. This approach will enable
rapid, precise determination of unknown phase shifts using interferometry.Comment: 6 pages, 4 figure
CFD Simulation and Analysis of the Combined Evaporative Cooling and Radiant Ceiling Air-conditioning System
Due to such disadvantages as large air duct and high energy consumption of the current all- outdoor air evaporative cooling systems used in the dry region of Northwest China, as well as the superiority of the ceiling cooling system in improving thermal comfort and saving energy, a combined system is presented in this paper. It combines an evaporative cooling system with ceiling cooling, in which the evaporative cooling system handles the entire latent load and one part of the sensible loads, and the ceiling cooling system deals with the other part of sensible loads in the air-conditioned zone, so that the condensation on radiant panels and the insufficiency of cooling capacity can be avoided. The cooling water at 18? used in the cooling coils of ceiling cooling system can be ground water, tap water or the cooled water from cooling towers in the summer.
This new air-conditioning system and existing all- outdoor air evaporative cooling system are applied to a project in the city of Lanzhou. Energy consumption analysis of the building is carried out using the energy consumption code. Velocity and temperature distribution in the air-conditioned zone is computed using CFD. According to the results, the energy consumption and indoor human thermal comfort of both systems are then compared. It is concluded that the new system occupies less building space, reduces energy consumption, improves indoor human thermal comfort and saves initial investment
Black hole thermodynamics and modified GUP consistent with doubly special relativity
We study the black hole thermodynamics and obtain the correction terms for
temperature, entropy, and heat capacity of the Schwarzschild black hole,
resulting from the commutation relations in the framework of {\it Modified
Generalized Uncertainty Principle} suggested by {\it Doubly Special
Relativity}.Comment: 13 pages, 6 figures, minor revision, references adde
Spin-Orbit Coupling and Ion Displacements in Multiferroic TbMnO3
The electronic and magnetic properties of TbMnO3 leading to its ferroelectric
(FE) polarization were investigated on the basis of relativistic density
functional theory (DFT) calculations. In agreement with experiment, we show
that the spin-spiral plane of TbMnO3 can be either the bc- or ab-plane, but not
the ac-plane. As for the mechanism of FE polarization, our work reveals that
the "pure electronic" model by Katsura, Nagaosa and Balatsky (KNB) is
inadequate in predicting the absolute direction of FE polarization. For the
ab-plane spin-spiral state of TbMnO3, the direction of FE polarization
predicted by the KNB model is opposite to that predicted by DFT calculations.
In determining the magnitude and the absolute direction of FE polarization in
spin-spiral states, it is found crucial to consider the displacements of the
ions from their ecntrosymmetric positions
Percutaneous pulmonary valve implantation in patients with right ventricular outflow tract dysfunction : A systematic review and meta-analysis
Background: Pulmonary valve replacement is required for patients with right ventricular outflow tract (RVOT) dysfunction. Surgical and percutaneous pulmonary valve replacement are the treatment options. Percutaneous pulmonary valve implantation (PPVI) provides a less-invasive therapy for patients. The aim of this study was to evaluate the effectiveness and safety of PPVI and the optimal time for implantation. Methods: We searched PubMed, EMBASE, Clinical Trial, and Google Scholar databases covering the period until May 2018. The primary effectiveness endpoint was the mean RVOT gradient; the secondary endpoints were the pulmonary regurgitation fraction, left and right ventricular end-diastolic and systolic volume indexes, and left ventricular ejection fraction. The safety endpoints were the complication rates. Results: A total of 20 studies with 1246 participants enrolled were conducted. The RVOT gradient decreased significantly [weighted mean difference (WMD) = -19.63 mmHg; 95% confidence interval (CI): -21.15, -18.11; p < 0.001]. The right ventricular end-diastolic volume index (RVEDVi) was improved (WMD = -17.59 ml/m(2); 95% CI: -20.93, -14.24; p < 0.001), but patients with a preoperative RVEDVi >140 ml/m(2) did not reach the normal size. Pulmonary regurgitation fraction (PRF) was notably decreased (WMD = -26.27%, 95% CI: -34.29, -18.25; p < 0.001). The procedure success rate was 99% (95% CI: 98-99), with a stent fracture rate of 5% (95% CI: 4-6), the pooled infective endocarditis rate was 2% (95% CI: 1-4), and the incidence of reintervention was 5% (95% CI: 4-6). Conclusions: In patients with RVOT dysfunction, PPVI can relieve right ventricular remodeling, improving hemodynamic and clinical outcomes
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