Estimating Social Influence Using Latent Space Adjusted Approach in R

Social influence, sometimes referred to as spillover or contagion, have been extensively studied in various empirical social network research. However, there are various estimation challenges in identifying social influence effects, as they are often entangled with other factors, such as homophily in the selection process, the individual's preference for the same social settings, etc. Methods currently available either do not solve these problems or require strong assumptions. Recent works by Xu 2018 and others show that a latent-space adjusted approach based on the latent space model has potential to disentangle the influence from other processes, and the simulation evidence shows the approach performs better than other state-of-the-art approaches in terms of recovering the true social influence effect when there is an unobserved trait co-determining influence and selection. In this paper we illustrate how latent space adjusted approach accounts for bias in the estimation of the social influence effect, and demonstrate how this approach can be implemented to estimate various social influence models with an empirical example in R.Comment: 15 pages, 2 figure

Asymptotics of the entropy production rate for dd-dimensional Ornstein-Uhlenbeck processes

In the context of non-equilibrium statistical physics, the entropy production rate is an important concept to describe how far a specific state of a system is from its equilibrium state. In this paper, we establish a central limit theorem and a moderate deviation principle for the entropy production rate of $d$-dimensional Ornstein-Uhlenbeck processes, by the techniques of functional inequalities such as Poincar\'e inequality and log-Sobolev inequality. As an application, we obtain a law of iterated logarithm for the entropy production rate

Entropy and weak solutions in the LBGK model

In this paper, we derive entropy functions whose local equilibria are suitable to recover the Euler-like equations in the framework of the Lattice Boltzmann method. Numerical examples are also given, which are consistent with the above theoretical arguments.Comment: 13pages,2 figure

Divergent bulk photovoltaic effect in Weyl semimetals

Weyl semimetals (WSM) have been discovered in time-reversal symmetric materials, featuring monopoles of Berry's curvature in momentum space. WSM have been distinguished between Type-I and II where the velocity tilting of the cone in the later ensures a finite area Fermi surface. To date it has not been clear whether the two types results in any qualitatively new phenomena. Here we focus on the shift-current response ($\sigma_{shift}(\omega)$), a second order optical effect generating photocurrents. Surprisingly we find that up to an order unity constant, $\sigma_{shift}(\omega)\sim \frac{e^3}{h^2}\frac{1}{\omega}$ in Type-II WSM, diverging in the low frequency $\omega\rightarrow 0$ limit. This is in stark contrast to the vanishing behavior ($\sigma_{shift}(\omega)\propto \omega$) in Type-I WSM. In addition, in both Type-I and Type-II WSM, a nonzero chemical potential $\mu$ relative to nodes leads to a large peak of shift-current response with a width $\sim |\mu|/\hbar$ and a height $\sim \frac{e^3}{h}\frac{1}{|\mu|}$, the latter diverging in the low doping limit. We show that the origin of these divergences is the singular Berry's connections and the Pauli-blocking mechanism. Similar results hold for the real part of the second harmonic generation, a closely related nonlinear optical response.Comment: 10 pages, 4 figures, a new appendix is added, which expands the discussion of second-harmonic generatio

Kinetic Energy-Based Temperature Computation in Non-Equilibrium Molecular Dynamics Simulation

The average kinetic energy is widely used to characterize temperature in molecular dynamics (MD) simulation. In this letter, the applicability of three types of average kinetic energy as measures of temperature is investigated, i.e., the total kinetic energy, kinetic energy without the centroid translation part, and thermal disturbance kinetic energy. Our MD simulations indicate that definitions of temperature based on the kinetic energy including rigid translational or rotational motion may yield unrealistic results. In contrast, the thermal disturbance kinetic energy has wider applicability to temperature computation in non-equilibrium molecular dynamics simulation. If small samples need to be used for local temperature, then a calibration approach is proposed to eliminate the sample-size dependence of the average disturbance kinetic energy.Comment: 4 figure

Large deviation principle of occupation measures for Non-linear monotone SPDEs

Using the hyper-exponential recurrence criterion, a large deviation principle for the occupation measure is derived for a class of non-linear monotone stochastic partial differential equations. The main results are applied to many concrete SPDEs such as stochastic $p$-Laplace equation, stochastic porous medium equation, stochastic fast-diffusion equation, and even stochastic real Ginzburg-Landau equation driven by $\alpha$-stable noises.Comment: This paper generalizes the idea in our NOT published paper arXiv:1510.03522. There is a substantial overlap with arXiv:1510.0352

Irreducibility of stochastic real Ginzburg-Landau equation driven by α\alpha-stable noises and applications

We establish the irreducibility of stochastic real Ginzburg-Landau equation with $\alpha$-stable noises by a maximal inequality and solving a control problem. As applications, we prove that the system converges to its equilibrium measure with exponential rate under a topology stronger than total variation and obeys the moderate deviation principle by constructing some Lyapunov test functions.Comment: Bernoulli (accepted). arXiv admin note: text overlap with arXiv:1410.724

Large deviation principle of occupation measure for stochastic real Ginzburg-Landau equation driven by α\alpha-stable noises

We establish a large deviation principle for the occupation measure of the stochastic real Ginzburg-Landau equation driven by $\alpha$-stable noises. The proof is based on a hyper-exponential recurrence criterion. Our result indicates a phenomenon that strong dissipation beats heavy tailed noises to produce a large deviation, it seems to us that this phenomenon has not been reported in the known literatures.Comment: This paper fills the gap in the paper arXiv:1410.7247 which has been withdrawn. We complete the proof in arXiv:1410.7247. arXiv admin note: text overlap with arXiv:1510.0190

The phase structure of black D1/D5 (F/NS5) system in canonical ensemble

In this paper, we explore means which can be used to change qualitatively the phase structure of charged black systems. For this, we consider a system of black D1/D5 (or its S-dual F/NS5). We find that the delocalized charged black D-strings (F-strings) alone share the same phase structure as the charged black D5 branes (NS5-branes), having no van der Waals-Maxwell liquid-gas type. However, when the two are combined to form D1/D5 (F/NS5), the resulting phase diagram has been changed dramatically to a richer one, containing now the above liquid-gas type. The effect of adding the charged D-strings (F-strings) on the phase structure can also be effectively described as a slight increase of the transverse dimensions to the original D5 (NS5). This may be viewed as a connection between a brane charge and a fraction of spatial dimension at least in a thermodynamical sense.Comment: 31 pages, 3 Figures, 2 Tables, minor corrections, version published in JHE

Dyonic Lieb-Shultz-Mattis Theorem and Symmetry Protected Topological Phases in Decorated Dimer Models

We consider 2+1D lattice models of interacting bosons or spins, with both magnetic flux and fractional spin in the unit cell. We propose and prove a modified Lieb-Shultz Mattis (LSM) theorem in this setting, which applies even when the spin in the enlarged magnetic unit cell is integral. There are two nontrivial outcomes for gapped ground states that preserve all symmetries. In the first case, one necessarily obtains a symmetry protected topological (SPT) phase with protected edge states. This allows us to readily construct models of SPT states by decorating dimer models of Mott insulators to yield SPT phases, which should be useful in their physical realization. In the second case, exotic bulk excitations, i.e. topological order, is necessarily present. While both scenarios require fractional spin in the lattice unit cell, the second requires that the symmetries protecting the fractional spin is related to that involved in the magnetic translations. Our discussion encompasses the general notion of fractional spin (projective symmetry representations) and magnetic flux (magnetic translations tied to a symmetry generator). The resulting SPTs display a dyonic character in that they associate charge with symmetry flux, allowing the flux in the unit cell to screen the projective representation on the sites. We provide an explicit formula that encapsulates this physics, which identifies a specific set of allowed SPT phases.Comment: 25 pages, 16 figure