Emergence of directed motion in a 2D system of Yukawa particles on 1D Ratchet

2022 ◽  
pp. 126913
Author(s):  
Anshika Chugh ◽  
Rajaraman Ganesh
Keyword(s):  
Directed Motion ◽  
2D System

The Fluctuating Lattice Boltzmann

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Brownian Motion ◽  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Thermal Fluctuations ◽  
Directed Motion ◽  
Statistical Fluctuations ◽  
Lattice Boltzmann Models ◽  
Motion Versus ◽  
The Way

Fluid flow at nanoscopic scales is characterized by the dominance of thermal fluctuations (Brownian motion) versus directed motion. Thus, at variance with Lattice Boltzmann models for macroscopic flows, where statistical fluctuations had to be eliminated as a major cause of inefficiency, at the nanoscale they have to be summoned back. This Chapter illustrates the “nemesis of the fluctuations” and describe the way they have been inserted back within the LB formalism. The result is one of the most active sectors of current Lattice Boltzmann research.

scholarly journals Angle-resolved spectroscopy of electron-electron scattering in a 2D system

2001 ◽  
Vol 56 (5) ◽  
pp. 709-715 ◽  
Author(s):  
A. V Yanovsky ◽  
H Predel ◽  
H Buhmann ◽  
R. N Gurzhi ◽  
A. N Kalinenko ◽  
...  
Keyword(s):  
Electron Scattering ◽  
2D System

DIRECTED MOTION OF BROWNIAN MOTORS: A RATCHET MODEL OF TWO-COUPLED MOLECULAR MOTORS

2007 ◽  
Vol 21 (28) ◽  
pp. 1915-1921 ◽  
Author(s):  
SHUTANG WEN ◽  
HONGWEI ZHANG ◽  
LEIAN LIU ◽  
XIAOFENG SUN ◽  
YUXIAO LI
Keyword(s):  
Molecular Motors ◽  
Particle System ◽  
Langevin Equations ◽  
Transition Rates ◽  
Neck Length ◽  
Directed Motion ◽  
Mean Velocity ◽  
Positive Direction ◽  
Brownian Motors ◽  
The Individual

We investigated the motion of two-head Brownian motors by introducing a model in which the two heads coupled through an elastic spring is subjected to a stochastic flashing potential. The ratchet potential felt by the individual head is anti-correlated. The mean velocity was calculated based on Langevin equations. It turns out that we can obtain a unidirectional current. The current is sensitive to the transition rates and neck length and other parameters. The coupling of transition rate and neck length leads to variations both in the values and directions of currency. With a larger neck length, the bi-particle system has a larger velocity in one direction, while with a smaller neck length, it has a smaller velocity in the other direction. This is very likely the case of myosins with a larger neck length and larger velocity in the positive direction of filaments and kinesins with a smaller neck length and smaller velocity in the negative direction of microtubules. We also further investigated how current reversal depended on the neck length and the transition rates.

RENORMALIZATION OF FERMI VELOCITY IN A COMPOSITE TWO DIMENSIONAL ELECTRON GAS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 87-94 ◽  
Author(s):  
M. WEGER ◽  
L. BURLACHKOV
Keyword(s):  
Electron Gas ◽  
Fermi Velocity ◽  
Bohr Radius ◽  
Dimensional Electron ◽  
Temperature Dependent ◽  
Two Dimensional Electron Gas ◽  
Self Energy ◽  
2D System ◽  
Dimensional Electron Gas ◽  
The One

We calculate the self-energy Σ(k, ω) of an electron gas with a Coulomb interaction in a composite 2D system, consisting of metallic layers of thickness d ≳ a 0, where a 0 = ħ2∊1/ me 2 is the Bohr radius, separated by layers with a dielectric constant ∊2 and a lattice constant c perpendicular to the planes. The behavior of the electron gas is determined by the dimensionless parameters k F a 0 and k F c ∊2/∊1. We find that when ∊2/∊1 is large (≈5 or more), the velocity v(k) becomes strongly k-dependent near k F , and v ( k F ) is enhanced by a factor of 5-10. This behavior is similar to the one found by Lindhard in 1954 for an unscreened electron gas; however here we take screening into account. The peak in v(k) is very sharp (δ k/k F is a few percent) and becomes sharper as ∊2/∊1 increases. This velocity renormalization has dramatic effects on the transport properties; the conductivity at low T increases like the square of the velocity renormalization and the resistivity due to elastic scattering becomes temperature dependent, increasing approximately linearly with T. For scattering by phonons, ρ ∝ T 2. Preliminary measurements suggest an increase in v k in YBCO very close to k F .

Activation of the Human Superior Temporal Gyrus during Observation of Goal Attribution by Intentional Objects

2004 ◽  
Vol 16 (10) ◽  
pp. 1695-1705 ◽  
Author(s):  
Johannes Schultz ◽  
Hiroshi Imamizu ◽  
Mitsuo Kawato ◽  
Chris D. Frith
Keyword(s):  
Functional Imaging ◽  
Superior Temporal Gyrus ◽  
Target Object ◽  
Directed Motion ◽  
Intentional Objects ◽  
Geometrical Shapes ◽  
Goal Attribution ◽  
Complex Goal

Previous functional imaging experiments in humans showed activation increases in the posterior superior temporal gyrus and sulcus during observation of geometrical shapes whose movements appear intentional or goal-directed. We modeled a chase scenario between two objects, in which the chasing object used different strategies to reach the target object: The chaser either followed the target's path or appeared to predict its end position. Activation in the superior temporal gyrus of human observers was greater when the chaser adopted a predict rather than a follow strategy. Attending to the chaser's strategy induced slightly greater activation in the left superior temporal gyrus than attending to the outcome of the chase. These data implicate the superior temporal gyrus in the identification of objects displaying complex goal-directed motion.

scholarly journals Topological Quantum Computing and 3-Manifolds

2021 ◽  
Vol 3 (1) ◽  
pp. 153-165
Author(s):  
Torsten Asselmeyer-Maluga
Keyword(s):  
Quantum Computing ◽  
Berry Phase ◽  
Basic Structure ◽  
Quantum States ◽  
Point Of View ◽  
Surface Topology ◽  
Usual Sense ◽  
Closed Curves ◽  
Topological Quantum ◽  
2D System

In this paper, we will present some ideas to use 3D topology for quantum computing. Topological quantum computing in the usual sense works with an encoding of information as knotted quantum states of topological phases of matter, thus being locked into topology to prevent decay. Today, the basic structure is a 2D system to realize anyons with braiding operations. From the topological point of view, we have to deal with surface topology. However, usual materials are 3D objects. Possible topologies for these objects can be more complex than surfaces. From the topological point of view, Thurston’s geometrization theorem gives the main description of 3-dimensional manifolds. Here, complements of knots do play a prominent role and are in principle the main parts to understand 3-manifold topology. For that purpose, we will construct a quantum system on the complements of a knot in the 3-sphere. The whole system depends strongly on the topology of this complement, which is determined by non-contractible, closed curves. Every curve gives a contribution to the quantum states by a phase (Berry phase). Therefore, the quantum states can be manipulated by using the knot group (fundamental group of the knot complement). The universality of these operations was already showed by M. Planat et al.

Phoretic self-propulsion of helical active particles

2021 ◽  
Vol 927 ◽  
Author(s):  
Ruben Poehnl ◽  
William Uspal
Keyword(s):  
Particle Surface ◽  
Design Parameters ◽  
Strong Impact ◽  
Directed Motion ◽  
Concentration Gradients ◽  
Slender Body Theory ◽  
Active Particles ◽  
Straight Line ◽  
Judicious Choice ◽  
Body Theory

Chemically active colloids self-propel by catalysing the decomposition of molecular ‘fuel’ available in the surrounding solution. If the various molecular species involved in the reaction have distinct interactions with the colloid surface, and if the colloid has some intrinsic asymmetry in its surface chemistry or geometry, there will be phoretic flows in an interfacial layer surrounding the particle, leading to directed motion. Most studies of chemically active colloids have focused on spherical, axisymmetric ‘Janus’ particles, which (in the bulk, and in absence of fluctuations) simply move in a straight line. For particles with a complex (non-spherical and non-axisymmetric) geometry, the dynamics can be much richer. Here, we consider chemically active helices. Via numerical calculations and slender body theory, we study how the translational and rotational velocities of the particle depend on geometry and the distribution of catalytic activity over the particle surface. We confirm the recent finding of Katsamba et al. (J. Fluid Mech., vol. 898, 2020, p. A24) that both tangential and circumferential concentration gradients contribute to the particle velocity. The relative importance of these contributions has a strong impact on the motion of the particle. We show that, by a judicious choice of the particle design parameters, one can suppress components of angular velocity that are perpendicular to the screw axis, or even select for purely ‘sideways’ translation of the helix.

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