Search results for " Dynamic"

Explicit proton transfer in classical molecular dynamics simulations.

2014

We present Hydrogen Dynamics (HYDYN), a method that allows explicit proton transfer in classical force field molecular dynamics simulations at thermodynamic equilibrium. HYDYN reproduces the characteristic properties of the excess proton in water, from the special pair dance, to the continuous fluctuation between the limiting Eigen and Zundel complexes, and the water reorientation beyond the first solvation layer. Advantages of HYDYN with respect to existing methods are computational efficiency, microscopic reversibility, and easy parameterization for any force field peerReviewed

Exploring fast proton transfer events associated with lateral proton diffusion on the surface of membranes

2019

Proton diffusion (PD) across biological membranes is a fundamental process in many biological systems, and much experimental and theoretical effort has been employed for deciphering it. Here, we report on a spectroscopic probe, which can be tightly tethered to the membrane, for following fast (nanosecond) proton transfer events on the surface of membranes. Our probe is composed of a photoacid that serves as our light-induced proton source for the initiation of the PD process. We use our probe to follow PD, and its pH dependence, on the surface of lipid vesicles composed of a zwitterionic headgroup, a negative headgroup, a headgroup that is composed only from the negative phosphate group, or…

About numerical integration methods for pseudo-dynamic tests: state of the art

2007

Psychometric Evaluation of the Norwegian Versions of the Modified Group Environment Questionnaire and the Youth Sport Environment Questionnaire

2021

This study aimed to translate the modified Group Environment Questionnaire (GEQ) and the Youth Sport Environment Questionnaire (YSEQ) into Norwegian, examine the factor structure and reliability of the scales through independent clusters model confirmatory factor analysis (ICM-CFA) and exploratory structural equation modeling (ESEM), and examine differential item functioning (DIF) as a function of sex. Three-hundred-and-thirty-three athletes (M(SD)age  = 18.7(2.60) years; 33% females) completed the GEQ. Three-hundred-and-three athletes (M(SD)age  = 15.0(1.48) years; 26% females) completed the YSEQ. Results indicated acceptable fit indices for a four-factor, a second-order two-factor (task a…

Microsoft Dynamics Ax 2012 ātrdarbības uzlabošana

2015

Microsoft Dynamics Ax 2012 ir jaunākais produkts no Microsoft Dynamics Ax produktu saimes. Lai jaunie un esoši klienti būtu apmierināti sistēmas, ir jānodrošina ātra un stabila tās darbība. Bakalaura darba mērķis ir Microsoft Dynamics Ax 2012 ātrdarbības analīze un uzlabošana. Darba teorētiskajā daļā tiek apskatīta Microsoft Dynamics Ax 2012 sistēmas uzbūve un ātrdarbības testēšanas rīki. Darba praktiskajā daļā tiek veikti sistēmas ātrdarbības testi, un veiktas izmaiņas sistēmas konfigurācijā un programmas kodā. Darba rezultātā tika panākts sistēmas ātrdarbības uzlabojums.

Rayleigh-instability-driven dewetting of thin Au and Ag films on indium-tin-oxide surface under nanosecond laser irradiations

2013

Investigations have been carried out on laser-beam-induced nanoparticle (NP) formation in thin (5 nm) Au and Ag films on indium-tin-oxide substrate. After the irradiation the films were observed to break-up into NPs through a dewetting mechanism. This mechanism was investigated as a Rayleigh-instability- driven process. In fact, for each used laser fluence, the resulting Au and Ag NPs' mean size and surface-to-surface mean distance were quantified and correlated between them in the framework of the Rayleigh-instability theory showing an excellent agreement. © The Institution of Engineering and Technology 2013.

Quantum Correlation Dynamics in Controlled Two-Coupled-Qubit Systems

2020

We study and compare the time evolutions of concurrence and quantum discord in a driven system of two interacting qubits prepared in a generic Werner state. The corresponding quantum dynamics is exactly treated and manifests the appearance and disappearance of entanglement. Our analytical treatment transparently unveils the physical reasons for the occurrence of such a phenomenon, relating it to the dynamical invariance of the X structure of the initial state. The quantum correlations which asymptotically emerge in the system are investigated in detail in terms of the time evolution of the fidelity of the initial Werner state.

Enhancing Metastability by Dissipation and Driving in an Asymmetric Bistable Quantum System.

2018

The stabilizing effect of quantum fluctuations on the escape process and the relaxation dynamics from a quantum metastable state are investigated. Specifically, the quantum dynamics of a multilevel bistable system coupled to a bosonic Ohmic thermal bath in strong dissipation regime is analyzed. The study is performed by a non-perturbative method based on the real-time path integral approach of the Feynman-Vernon influence functional. We consider a strongly asymmetric double well potential with and without a monochromatic external driving, and with an out-of-equilibrium initial condition. In the absence of driving we observe a nonmonotonic behavior of the escape time from the metastable regi…

Vortex dynamics in rotating counterflow and plane Couette and Poiseuille turbulence in superfluid Helium

2008

An equation previously proposed to describe the evolution of vortex line density in rotating counterflow turbulent tangles in superfluid helium is generalized to incorporate nonvanishing barycentric velocity and velocity gradients. Our generalization is compared with an analogous approach proposed by Lipniacki, and with experimental results by Swanson et al. in rotating counterflow, and it is used to evaluate the vortex density in plane Couette and Poiseuille flows of superfluid helium.

Highly occupied gauge theories in 2 + 1 dimensions : a self-similar attractor

2019

Motivated by the boost-invariant Glasma state in the initial stages in heavy-ion collisions, we perform classical-statistical simulations of SU(2) gauge theory in 2+1 dimensional space-time both with and without a scalar field in the adjoint representation. We show that irrespective of the details of the initial condition, the far-from-equilibrium evolution of these highly occupied systems approaches a unique universal attractor at high momenta that is the same for the gauge and scalar sectors. We extract the scaling exponents and the form of the distribution function close to this non-thermal fixed point. We find that the dynamics are governed by an energy cascade to higher momenta with sc…