Checkerboard charge density wave and pseudogap in high-TcT_{c} cuprates

We consider the scenario where a 4-lattice constant, rotationally symmetric charge density wave (CDW) is present in the underdoped cuprates. We prove a theorem that puts strong constraint on the possible form factor of such a CDW. We demonstrate, within mean-field theory, that a particular form factor within the allowed class describes the angle-resolved photoemission and scan tunneling spectroscopy well. We conjecture that the ``large pseudogap'' in cuprates is the consequence of this type of charge density wave.Comment: We add a new section II on the symmetry property of the checkerboard CD

Soliton solutions of the improved quark mass density-dependent model at finite temperature

The improved quark mass density-dependent model (IQMDD) based on soliton bag model is studied at finite temperature. Appling the finite temperature field theory, the effective potential of the IQMDD model and the bag constant $B(T)$ have been calculated at different temperatures. It is shown that there is a critical temperature $T_{C}\simeq 110 \mathrm{MeV}$. We also calculate the soliton solutions of the IQMDD model at finite tmperature. It turns out that when $T<T_{C}$, there is a bag constant $B(T)$ and the soliton solutions are stable. However, when $T>T_{C}$ the bag constant $B(T)=0$ and there is no soliton solution, therefore, the confinement of quarks are removed quickly.Comment: 10 pages, 9 figures; Version to appear in Physical Review

The Hamiltonian structure and Euler-Poincar\'{e} formulation of the Vlasov-Maxwell and gyrokinetic systems

We present a new variational principle for the gyrokinetic system, similar to the Maxwell-Vlasov action presented in Ref. 1. The variational principle is in the Eulerian frame and based on constrained variations of the phase space fluid velocity and particle distribution function. Using a Legendre transform, we explicitly derive the field theoretic Hamiltonian structure of the system. This is carried out with a modified Dirac theory of constraints, which is used to construct meaningful brackets from those obtained directly from Euler-Poincar\'{e} theory. Possible applications of these formulations include continuum geometric integration techniques, large-eddy simulation models and Casimir type stability methods. [1] H. Cendra et. al., Journal of Mathematical Physics 39, 3138 (1998)Comment: 36 pages, 1 figur

Dependence of the flux creep activation energy on current density and magnetic field for MgB2 superconductor

Systematic ac susceptibility measurements have been performed on a MgB$_2$ bulk sample. We demonstrate that the flux creep activation energy is a nonlinear function of the current density $U(j)\propto j^{-0.2}$, indicating a nonlogarithmic relaxation of the current density in this material. The dependence of the activation energy on the magnetic field is determined to be a power law $U(B)\propto B^{-1.33}$, showing a steep decline in the activation energy with the magnetic field, which accounts for the steep drop in the critical current density with magnetic field that is observed in MgB$_2$. The irreversibility field is also found to be rather low, therefore, the pinning properties of this new material will need to be enhanced for practical applications.Comment: 11 pages, 6 figures, Revtex forma

Group properties and invariant solutions of a sixth-order thin film equation in viscous fluid

Using group theoretical methods, we analyze the generalization of a one-dimensional sixth-order thin film equation which arises in considering the motion of a thin film of viscous fluid driven by an overlying elastic plate. The most general Lie group classification of point symmetries, its Lie algebra, and the equivalence group are obtained. Similar reductions are performed and invariant solutions are constructed. It is found that some similarity solutions are of great physical interest such as sink and source solutions, travelling-wave solutions, waiting-time solutions, and blow-up solutions.Comment: 8 page

K-Connected Cores Computation in Large Dual Networks

© 2018, The Author(s). Computing k- cores is a fundamental and important graph problem, which can be applied in many areas, such as community detection, network visualization, and network topology analysis. Due to the complex relationship between different entities, dual graph widely exists in the applications. A dual graph contains a physical graph and a conceptual graph, both of which have the same vertex set. Given that there exist no previous studies on the k- core in dual graphs, we formulate a k-connected core (k- CCO) model in dual graphs. A k- CCO is a k- core in the conceptual graph, and also connected in the physical graph. Given a dual graph and an integer k, we propose a polynomial time algorithm for computing all k- CCOs. We also propose three algorithms for computing all maximum-connected cores (MCCO), which are the existing k- CCOs such that a (k+ 1) -CCO does not exist. We further study a subgraph search problem, which is computing a k- CCO that contains a set of query vertices. We propose an index-based approach to efficiently answer the query for any given parameter k. We conduct extensive experiments on six real-world datasets and four synthetic datasets. The experimental results demonstrate the effectiveness and efficiency of our proposed algorithms

Continuous distribution of frequencies and deformed dispersion relations

The possibilities that, in the realm of the detection of the so--called deformed dispersion relation, a light source with a continuous distribution of frequencies offers is discussed. It will be proved that the presence of finite coherence length entails the emergence of a new term in the interference pattern. This is a novel trait, which renders a new possibility in the quest for bounds associated with these deformed dispersion relations.Comment: Accepted in Classical and Quantum Gravit

Active fault-tolerant control for an internet-based networked three-tank system

This brief is concerned with the active fault-tolerant control (FTC) problem for an Internet-based networked three-tank system (INTTS) serving as a benchmark system for evaluating networked FTC algorithms. The INTTS has two parts located at Tsinghua University in China and at the University of South Wales in the U.K., respectively, which are connected via the Internet. With the INTTS as an experimental platform, the active FTC problem is investigated for a class of nonlinear networked systems subject to partial actuator failures. Once a specific actuator failure is detected and confirmed by a fault diagnosis unit, the control law is then reconfigured based on the information of the detected fault. Both the stability and the acceptable H∞ disturbance attenuation level are guaranteed for the closed-loop system using the remaining reliable actuators. Extensive experiments are carried out on the active FTC problem of the INTTS with partial actuator failures, and the effectiveness of the proposed scheme is illustrated.The work of X. He was supported in part by the Natural Science Foundation of China (NSFC) under Grant 61473163 and Grant 61522309 and in part by the Tsinghua University Initiative Scientific Research Program. The work of Z. Wang was supported by NSFC under Grant 61273156. The work of D. H. Zhou was supported in part by NSFC under Grant 61290324 and Grant 61490701 and in part by the Research Fund for the Taishan Scholar Project of Shandong Province of China. Recommended by Associate Editor L. Xie