نتایج جستجو برای: directed diffusion

تعداد نتایج: 318196  

2000
W. Wykes S. C. Chapman G. Rowlands

During periods of increased magnetospheric activity , whistler wave emissions have been observed with increased wave amplitudes. We consider a pitch angle diffusion mechanism that is shown to scale with whistler wave amplitude and hence is 'switched on' during these periods of intense activity. We consider the interaction between relativistic electrons and two oppositely directed, parallel prop...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2009
L Mollazadeh-Beidokhti J Deseigne D Lacoste F Mohammad-Rafiee H Schiessel

Heat-induced diffusion of nucleosomes along DNA is an experimentally well-studied phenomenon, presumably induced by twist defects that propagate through the wrapped DNA portion. The diffusion constant depends dramatically on the local mechanical properties of the DNA and the presence of DNA-binding ligands. This has been quantitatively understood by a stochastic three-state model. Future experi...

Journal: :Physical review letters 2005
Manuel Arrayás Marco A Fontelos José L Trueba

When a strong electric field is applied to nonconducting matter, narrow channels of plasma called streamers may form. Branchlike patterns of streamers have been observed in anode directed discharges. We explain a mechanism for branching as the result of a balance between the destabilizing effect of impact ionization and the stabilizing effect of electron diffusion on ionization fronts. The disp...

Introduction: Self-directed learning is one of the most practical competencies that makes a person independent in learning and paves lifelong learning. Due to the rapid growth of knowledge and technology in nursing, self-directed learning is more important. This study aimed to investigate the level of self-directed learning readiness in nursing students of Shahid Beheshti University of Medical ...

Journal: :Physical review letters 2008
Benjamin Lindner Ernesto M Nicola

We study the effect of an asymmetry on the transport properties of an active Brownian particle. We demonstrate the existence of a critical force or, more generally, of a critical asymmetry that separates parameter regimes of giant diffusion from those with reliable directed transport. We derive a condition for the critical asymmetry by means of an exact expression for the diffusion coefficient ...

2003
M. Schiavoni L. Sanchez-Palencia F. Renzoni G. Grynberg

094101-1 We demonstrate the phenomenon of directed diffusion in a symmetric periodic potential. This has been realized with cold atoms in a one-dimensional dissipative optical lattice. The stochastic process of optical pumping leads to a diffusive dynamics of the atoms through the periodic structure, while a zeromean force which breaks the temporal symmetry of the system is applied by phase mod...

2014
Reza Banirazi Edmond Jonckheere Bhaskar Krishnamachari

Concepts of temperature, heat, and entropy are extended to packet routing on multiclass wireless networks with particular challenges including network directionality, channel interference, channel capacity, time-varying topology, and stochastic arrivals. Applying thermodynamic principles in the framework of combinatorial geometry, a novel physics-oriented multiclass diffusion process is develop...

2008
W J Wykes S C Chapman

Using numerical solutions of single particle dynamics, we consider a chaotic electron-whistler interaction mechanism for enhanced diffusion in phase space. This process, when applied to parameters consistent with the Jovian magnetosphere, is a candidate mechanism for pitch angle scattering in the Io torus, thus providing a source of auroral precipitating electrons. We initially consider the int...

Journal: :Physical review 2023

We numerically investigate the quantum transport in a coupled kicked rotors with $\mathcal{PT}$-symmetric potential. find that spontaneous $\mathcal{PT}$-symmetry breaking of wavefunctions emerges when amplitude imaginary part complex potential is beyond threshold value, which can be modulated by coupling strength effectively. In regime breaking, particles driven periodical kicks move unidirect...

2014
Robert Ietswaart Florian Szardenings Kenn Gerdes Martin Howard

Low copy number plasmids in bacteria require segregation for stable inheritance through cell division. This is often achieved by a parABC locus, comprising an ATPase ParA, DNA-binding protein ParB and a parC region, encoding ParB-binding sites. These minimal components space plasmids equally over the nucleoid, yet the underlying mechanism is not understood. Here we investigate a model where Par...

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