11 documents found, page 1 of 2
A new field solver for modeling of relativistic particle-laser interactions usi...
Li, F.; Miller, K. G.; Xu, X.; Tsung, F. S.; Decyk, V. K.; An, W.; Fonseca, R. A.; Mori, W. B.A customized finite-difference field solver for the particle-in-cell (PIC) algorithm that provides higher fidelity for wave-particle interactions in intense electromagnetic waves is presented. In many problems of interest, particles with relativistic energies interact with intense electromagnetic fields that have phase velocities near the speed of light. Numerical errors can arise due to (1) dispersion errors i...
Crowdsourcing hypothesis tests: making transparent how design choices shape res...
Landy, J. F.; Jia; M.; Ding, I. L.; Viganola, D.; Tierney, W; Dreber, A.; Johannesson, M.; Pfeiffer, T.; Ebersole, C.; Gronau, Q. F.; Ly, A.To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer five original research questions related to moral judgments, negotiations, and implicit cognition. Participants from 2 separate large samples (total N > 15,000) were then randomly assigned to complete 1 version of each study. Effect s...
Controlling the numerical Cerenkov instability in PIC simulations using a custo...
Li, F.; Yu, P. C.; Xu, X.; Fiuza, F.; Decyk, V. K.; Dalichaouch, T.; Davidson, A.; Tableman, A.; An, W.; Tsung, F. S.; Fonseca, R. A.; Lu, W.In this paper we present a customized finite-difference-time-domain (FDTD) Maxwell solver for the particle-in-cell (PIC) algorithm. The solver is customized to effectively eliminate the numerical Cerenkov instability (NCI) which arises when a plasma (neutral or non-neutral) relativistically drifts on a grid when using the PIC algorithm. We control the EM dispersion curve in the direction of the plasma drift of ...
Doctor-patient relationships (DPR) in China: managers and clinicians’ twofold p...
Ma, S.; Xu, X.; Trigo, V.; Ramalho, N. J. C.Purpose: The first objective of this research is to develop and test theory on how commitment human resource (HR) practices affect hospital professionals’ job satisfaction that motivates them to generate desirable patient care and subsequently improve doctor-patient relationships (DPR). The second objective is to examine how commitment HR practices influence in different ways hospital managers and clinicians. M...
Enabling Lorentz boosted frame particle-in-cell simulations of laser wakefield ...
Yu, P.; Xu, X.; Davidson, A.; Tableman, A.; Dalichaouch, T.; Li, F.; Meyers, M. D.; An, W.; Tsung, F. S.; Decyk, V. K.; Fiuza, F.; Vieira, J.When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at beta(b)c towards the laser, which can lead to a computational speedup of similar to gamma(2)(b)=(1-beta(2)(b))-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited n...
Mitigation of numerical Cerenkov radiation and instability using a hybrid finit...
Yu, P.; Xu, X.; Tableman, A.; Decyk, V. K.; Tsung, F. S.; Fiuza, F.; Vieira, J.; Davidson, A.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.A hybrid Maxwell solver for fully relativistic and electromagnetic (EM) particle-in-cell (PIC) codes is described. In this solver, the EM fields are solved in k space by performing an FFT in one direction, while using finite difference operators in the other direction(s). This solver eliminates the numerical Cerenkov radiation for particles moving in the preferred direction. Moreover, the numerical Cerenkov ins...
Elimination of the numerical Cerenkov instability for spectral EM-PIC codes
Yu, P.; Xu, X.; Decyk, V. K.; Fiuza, F.; Vieira, J.; Tsung, F. S.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.When using an electromagnetic particle-in-cell (EM-PIC) code to simulate a relativistically drifting plasma, a violent numerical instability known as the numerical Cerenkov instability (NCI) occurs. The NCI is due to the unphysical coupling of electromagnetic waves on a grid to wave-particle resonances, including aliased resonances, i.e., omega + 2 pi mu/Delta t = (k(1) + 2 pi v(1)/Delta x(1))nu(0), where mu an...
Convergence of genes and cellular pathways dysregulated in autism spectrum diso...
Pinto, D.; Delaby, E.; Merico, D.; Barbosa, M.; Merikangas, A.; Klei, L; Thiruvahindrapuram, B.; Xu, X.; Ziman, R.; Wang, Z.; Vorstman, J.A.Rare copy-number variation (CNV) is an important source of risk for autism spectrum disorders (ASDs). We analyzed 2,446 ASD-affected families and confirmed an excess of genic deletions and duplications in affected versus control groups (1.41-fold, p = 1.0 × 10(-5)) and an increase in affected subjects carrying exonic pathogenic CNVs overlapping known loci associated with dominant or X-linked ASD and intellectua...
Modeling of laser wakefield acceleration in Lorentz boosted frame using EM-PIC ...
Yu, P.; Xu, X.; Decyk, V. K.; An, W.; Vieira, J.; Tsung, F. S.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.Simulating laser wakefield acceleration (LWFA) in a Lorentz boosted frame in which the plasma drifts towards the laser with nu(b) can speed up the simulation by factors of gamma(2)(b) = (1 nu(2)(b)/c(2))(-1). In these simulations the relativistic drifting plasma inevitably induces a high frequency numerical instability that contaminates the interesting physics. Various approaches have been proposed to mitigate ...
Modeling of laser wakefield acceleration in Lorentz boosted frame using a Quasi...
Yu, P.; Davidson, A.; Xu, X.; Tableman, A.; Decyk, V. K.; Tsung, F. S.; Vieira, J.; Fonseca, R. A.; Lu, W.; Silva, L. O.; Mori, W. B.Recently it was proposed in [A. F. Lifschitz, et. al., J. Comp. Phys. 228, 1803 (2009)] that laser wakefield acceleration could be modeled efficiently using a particle-in-cell code in cylindrical coordinates if the fields and currents were expanded into Fourier modes in the azimuthal angle, ?. We have implemented this algorithm into OSIRIS, including a new rigorous charge conserving deposition routine applicabl...