Topological Superfluid Transition Induced by Periodically Driven Optical Lattice

We propose a scenario to create topological superfluid in a periodically driven two-dimensional square optical lattice. We study the phase diagram of a spin-orbit coupled s-wave pairing superfluid in a periodically driven two-dimensional square optical lattice. We find that a phase transition from a trivial superfluid to a topological superfluid occurs when the potentials of the optical lattices are periodically changed. The topological phase is called Floquet topological superfluid and can host Majorana fermions.Comment: 6 pages, 1 figure

Quantum Hall Effects in a Non-Abelian Honeycomb Lattice

We study the tunable quantum Hall effects in a non-Abelian honeycomb optical lattice which is a many-Dirac-points system. We find that the quantum Hall effects present different features as change as relative strengths of several perturbations. Namely, a gauge-field-dressed next-nearest-neighbor hopping can induce the quantum spin Hall effect and a Zeeman field can induce a so-called quantum anomalous valley Hall effect which includes two copies of quantum Hall states with opposite Chern numbers and counter-propagating edge states. Our study extends the borders of the field of quantum Hall effects in honeycomb optical lattice when the internal valley degrees of freedom enlarge.Comment: 7 pages, 6 figure

Flood Routing Based on Diffusion Wave Equation Using Lattice Boltzmann Method

AbstractOne-dimensional diffusion wave equation is a simplified form of the full Saint Venant equations by neglecting the inertia terms. In this study, the Lattice Boltzmann method for the linear diffusion wave equation was developed. In order to verify the calculation accuracy of it, the analytical solution and Muskingum method were also introduced. Excellent agreement was obtained between observed data and numerical prediction. The results show that the Lattice Boltzmann method is a very competitive method for solving diffusion wave equation in terms of computational efficiency and accuracy

Lattice Boltzmann modeling of contact angle and its hysteresis in two-phase flow with large viscosity difference

Contact angle hysteresis is an important physical phenomenon omnipresent in nature and various industrial processes, but its effects are not considered in many existing multiphase flow simulations due to modeling complexity. In this work, a multiphase lattice Boltzmann method (LBM) is developed to simulate the contact-line dynamics with consideration of the contact angle hysteresis for a broad range of kinematic viscosity ratios. In this method, the immiscible two-phase flow is described by a color-fluid model, in which the multiple-relaxation-time collision operator is adopted to increase numerical stability and suppress unphysical spurious currents at the contact line. The contact angle hysteresis is introduced using the strategy proposed by Ding and Spelt [Ding and Spelt, J. Fluid Mech. 599, 341 (2008)], and the geometrical wetting boundary condition is enforced to obtain the desired contact angle. This method is first validated by simulations of static contact angle and dynamic capillary intrusion process on ideal (smooth) surfaces. It is then used to simulate the dynamic behavior of a droplet on a nonideal (inhomogeneous) surface subject to a simple shear flow. When the droplet remains pinned on the surface due to hysteresis, the steady interface shapes of the droplet quantitatively agree well with the previous numerical results. Four typical motion modes of contact points, as observed in a recent study, are qualitatively reproduced with varying advancing and receding contact angles. The viscosity ratio is found to have a notable impact on the droplet deformation, breakup, and hysteresis behavior. Finally, this method is extended to simulate the droplet breakup in a microfluidic T junction, with one half of the wall surface ideal and the other half nonideal. Due to the contact angle hysteresis, the droplet asymmetrically breaks up into two daughter droplets with the smaller one in the nonideal branch channel, and the behavior of daughter droplets is significantly different in both branch channels. Also, it is found that the contact angle hysteresis is strengthened with decreasing the viscosity ratio, leading to an earlier droplet breakup and a decrease in the maximum length that the droplet can reach before the breakup. These simulation results manifest that the present multiphase LBM can be a useful substitute to Ba et al. [Phys. Rev. E 88, 043306 (2013)] for modeling the contact angle hysteresis, and it can be easily implemented with higher computational efficiency

Efficacy of radiotherapy in patients with rectal cancer undergoing chemotherapy and surgery: a retrospective study based on the SEER database

Objective·To evaluate the survival effects of neoadjuvant radiation therapy and adjuvant radiotherapy on the patients with rectal cancer treated with chemotherapy and surgery by using the Surveillance, Epidemiology and End Results (SEER) database of the United States.Methods·The patients with pathologically confirmed rectal cancer and treated with chemotherapy and surgical resection from 2005 to 2015 in the SEER database were included; the patients with autopsy or death-only proof of rectal cancer, or without follow-up time and incomplete clinical data were excluded. All the patients were divided into neoadjuvant radiotherapy combined with surgery group (RT+S group), surgical treatment group (S group) and surgery combined with adjuvant radiotherapy group (S+RT group). The propensity score matching (PSM) was used to match the included subjects in each group at the 1∶1 ratio, and the restricted mean survival time (RMST) was used to estimate the mean survival of rectal cancer patients over 5 and 10 years. Cox proportional risk models were used to determine the effects of neoadjuvant and adjuvant radiotherapies on overall survival (OS) and tumor-specific survival (CSS) in the patients with rectal cancer, and the specific benefit groups of neoadjuvant and adjuvant radiotherapies were determined by stratified analysis of patients.Results·From 2005 to 2015, 8 975 patients with rectal cancer who received chemotherapy and surgery were included, including 1 079 in the S group, 5 991 in the RT+S group, and 1 905 in the S+RT group. After PSM, the clinical base characteristics of the groups were balanced and comparable. The patients in the RT+S group had a significantly improved prognosis in 5 and 10 years compared with the S group (all P=0.000) after PSM, while the patients in the S+RT group had a significantly improved prognosis in 5 years only (both P0.05). Multivariate Cox regression analysis showed that neoadjuvant radiotherapy was an independent protective factor for the patients′ OS and CSS (both P=0.000), while adjuvant radiotherapy was not (both P>0.05). Subgroup analysis showed that neoadjuvant radiotherapy had no significant protective effect on OS and CSS in the patients aged0.05); whereas adjuvant radiotherapy had significant protective effects on OS and CSS in the patients with poorly differentiated/undifferentiated tumors, tumor size>50 mm or TNM stage Ⅳ (all P50 mm, or TNM stage Ⅳ may benefit from adjuvant radiotherapy

Robust joint analysis allowing for model uncertainty in two-stage genetic association studies

<p>Abstract</p> <p>Background</p> <p>The cost efficient two-stage design is often used in genome-wide association studies (GWASs) in searching for genetic loci underlying the susceptibility for complex diseases. Replication-based analysis, which considers data from each stage separately, often suffers from loss of efficiency. Joint test that combines data from both stages has been proposed and widely used to improve efficiency. However, existing joint analyses are based on test statistics derived under an assumed genetic model, and thus might not have robust performance when the assumed genetic model is not appropriate.</p> <p>Results</p> <p>In this paper, we propose joint analyses based on two robust tests, MERT and MAX3, for GWASs under a two-stage design. We developed computationally efficient procedures and formulas for significant level evaluation and power calculation. The performances of the proposed approaches are investigated through the extensive simulation studies and a real example. Numerical results show that the joint analysis based on the MAX3 test statistic has the best overall performance.</p> <p>Conclusions</p> <p>MAX3 joint analysis is the most robust procedure among the considered joint analyses, and we recommend using it in a two-stage genome-wide association study.</p