keyword
MENU ▼
Read by QxMD icon Read
search

Planck space

keyword
https://www.readbyqxmd.com/read/28429787/heat-temperature-and-clausius-inequality-in-a-model-for-active-brownian-particles
#1
Umberto Marini Bettolo Marconi, Andrea Puglisi, Claudio Maggi
Methods of stochastic thermodynamics and hydrodynamics are applied to a recently introduced model of active particles. The model consists of an overdamped particle subject to Gaussian coloured noise. Inspired by stochastic thermodynamics, we derive from the system's Fokker-Planck equation the average exchanges of heat and work with the active bath and the associated entropy production. We show that a Clausius inequality holds, with the local (non-uniform) temperature of the active bath replacing the uniform temperature usually encountered in equilibrium systems...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28320903/phase-space-methods-for-the-spin-dynamics-in-condensed-matter-systems
#2
Jérôme Hurst, Paul-Antoine Hervieux, Giovanni Manfredi
Using the phase-space formulation of quantum mechanics, we derive a four-component Wigner equation for a system composed of spin-[Formula: see text] fermions (typically, electrons) including the Zeeman effect and the spin-orbit coupling. This Wigner equation is coupled to the appropriate Maxwell equations to form a self-consistent mean-field model. A set of semiclassical Vlasov equations with spin effects is obtained by expanding the full quantum model to first order in the Planck constant. The corresponding hydrodynamic equations are derived by taking velocity moments of the phase-space distribution function...
April 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28306551/master-equations-and-the-theory-of-stochastic-path-integrals
#3
Markus F Weber, Erwin Frey
This review provides a pedagogic and self-contained introduction to master equations and to their representation by path integrals. Since the 1930s, master equations have served as a fundamental tool to understand the role of fluctuations in complex biological, chemical, and physical systems. Despite their simple appearance, analyses of master equations most often rely on low-noise approximations such as the Kramers-Moyal or the system size expansion, or require ad-hoc closure schemes for the derivation of low-order moment equations...
April 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/28297839/probabilistic-approach-to-nonlinear-wave-particle-resonant-interaction
#4
A V Artemyev, A I Neishtadt, A A Vasiliev, D Mourenas
In this paper we provide a theoretical model describing the evolution of the charged-particle distribution function in a system with nonlinear wave-particle interactions. Considering a system with strong electrostatic waves propagating in an inhomogeneous magnetic field, we demonstrate that individual particle motion can be characterized by the probability of trapping into the resonance with the wave and by the efficiency of scattering at resonance. These characteristics, being derived for a particular plasma system, can be used to construct a kinetic equation (or generalized Fokker-Planck equation) modeling the long-term evolution of the particle distribution...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28243720/extracting-cellular-automaton-rules-from-physical-langevin-equation-models-for-single-and-collective-cell-migration
#5
J M Nava-Sedeño, H Hatzikirou, F Peruani, A Deutsch
Cellular automata (CA) are discrete time, space, and state models which are extensively used for modeling biological phenomena. CA are "on-lattice" models with low computational demands. In particular, lattice-gas cellular automata (LGCA) have been introduced as models of single and collective cell migration. The interaction rule dictates the behavior of a cellular automaton model and is critical to the model's biological relevance. The LGCA model's interaction rule has been typically chosen phenomenologically...
February 27, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28208407/stochastically-gated-local-and-occupation-times-of-a-brownian-particle
#6
Paul C Bressloff
We generalize the Feynman-Kac formula to analyze the local and occupation times of a Brownian particle moving in a stochastically gated one-dimensional domain. (i) The gated local time is defined as the amount of time spent by the particle in the neighborhood of a point in space where there is some target that only receives resources from (or detects) the particle when the gate is open; the target does not interfere with the motion of the Brownian particle. (ii) The gated occupation time is defined as the amount of time spent by the particle in the positive half of the real line, given that it can only cross the origin when a gate placed at the origin is open; in the closed state the particle is reflected...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28157360/redefining-the-axion-window
#7
Luca Di Luzio, Federico Mescia, Enrico Nardi
A major goal of axion searches is to reach inside the parameter space region of realistic axion models. Currently, the boundaries of this region depend on somewhat arbitrary criteria, and it would be desirable to specify them in terms of precise phenomenological requirements. We consider hadronic axion models and classify the representations R_{Q} of the new heavy quarks Q. By requiring that (i) the Q's are sufficiently short lived to avoid issues with long-lived strongly interacting relics, (ii) no Landau poles are induced below the Planck scale; 15 cases are selected which define a phenomenologically preferred axion window bounded by a maximum (minimum) value of the axion-photon coupling about 2 times (4 times) larger than is commonly assumed...
January 20, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/27820827/effect-of-ionic-diffusion-on-extracellular-potentials-in-neural-tissue
#8
Geir Halnes, Tuomo Mäki-Marttunen, Daniel Keller, Klas H Pettersen, Ole A Andreassen, Gaute T Einevoll
Recorded potentials in the extracellular space (ECS) of the brain is a standard measure of population activity in neural tissue. Computational models that simulate the relationship between the ECS potential and its underlying neurophysiological processes are commonly used in the interpretation of such measurements. Standard methods, such as volume-conductor theory and current-source density theory, assume that diffusion has a negligible effect on the ECS potential, at least in the range of frequencies picked up by most recording systems...
November 2016: PLoS Computational Biology
https://www.readbyqxmd.com/read/27470597/fokker-planck-formalism-in-magnetic-resonance-simulations
#9
Ilya Kuprov
This paper presents an overview of the Fokker-Planck formalism for non-biological magnetic resonance simulations, describes its existing applications and proposes some novel ones. The most attractive feature of Fokker-Planck theory compared to the commonly used Liouville - von Neumann equation is that, for all relevant types of spatial dynamics (spinning, diffusion, stationary flow, etc.), the corresponding Fokker-Planck Hamiltonian is time-independent. Many difficult NMR, EPR and MRI simulation problems (multiple rotation NMR, ultrafast NMR, gradient-based zero-quantum filters, diffusion and flow NMR, off-resonance soft microwave pulses in EPR, spin-spin coupling effects in MRI, etc...
September 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27374418/space-charge-limited-release-of-charged-inverse-micelles-in-non-polar-liquids
#10
Manoj Prasad, Filip Strubbe, Filip Beunis, Kristiaan Neyts
Charged inverse micelles (CIMs) generated during a continuous polarizing voltage between electrodes in the model system of polyisobutylene succinimide in dodecane do not populate a diffuse double layer like CIMs present in equilibrium (regular CIMs), but instead end up in interface layers. When the applied voltage is reversed abruptly after a continuous polarizing voltage step, two peaks are observed in the transient current. The first peak is due to the release of regular CIMs from the diffuse double layers formed during the polarizing voltage step, which is understood on the basis of the Poisson-Nernst-Planck equations...
July 28, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27314711/litmus-test-for-cosmic-hemispherical-asymmetry-in-the-cosmic-microwave-background-b-mode-polarization
#11
Suvodip Mukherjee, Tarun Souradeep
Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements...
June 3, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27300952/introduction-of-effective-dielectric-constant-to-the-poisson-nernst-planck-model
#12
Atsushi Sawada
The Poisson-Nernst-Planck (PNP) model has been widely used for analyzing impedance or dielectric spectra observed for dilute electrolytic cells. In the analysis, the behavior of mobile ions in the cell under an external electric field has been explained by a conductive nature regardless of ionic concentrations. However, if the cell has parallel-plate blocking electrodes, the mobile ions may also play a role as a dielectric medium in the cell by the effect of space-charge polarization when the ionic concentration is sufficiently low...
May 2016: Physical Review. E
https://www.readbyqxmd.com/read/27276940/generalized-quantum-fokker-planck-equation-for-photoinduced-nonequilibrium-processes-with-positive-definiteness-condition
#13
Seogjoo Jang
This work provides a detailed derivation of a generalized quantum Fokker-Planck equation (GQFPE) appropriate for photo-induced quantum dynamical processes. The path integral method pioneered by Caldeira and Leggett (CL) [Physica A 121, 587 (1983)] is extended by utilizing a nonequilibrium influence functional applicable to different baths for the ground and the excited electronic states. Both nonequilibrium and non-Markovian effects are accounted for consistently by expanding the paths in the exponents of the influence functional up to the second order with respect to time...
June 7, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27104690/thermodynamic-entropy-as-a-noether-invariant
#14
Shin-Ichi Sasa, Yuki Yokokura
We study a classical many-particle system with an external control represented by a time-dependent extensive parameter in a Lagrangian. We show that thermodynamic entropy of the system is uniquely characterized as the Noether invariant associated with a symmetry for an infinitesimal nonuniform time translation t→t+ηℏβ, where η is a small parameter, ℏ is the Planck constant, β is the inverse temperature that depends on the energy and control parameter, and trajectories in the phase space are restricted to those consistent with quasistatic processes in thermodynamics...
April 8, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27063927/adaptation-of-pancreatic-islet-cyto-architecture-during-development
#15
Deborah A Striegel, Manami Hara, Vipul Periwal
Plasma glucose in mammals is regulated by hormones secreted by the islets of Langerhans embedded in the exocrine pancreas. Islets consist of endocrine cells, primarily α, β, and δ cells, which secrete glucagon, insulin, and somatostatin, respectively. β cells form irregular locally connected clusters within islets that act in concert to secrete insulin upon glucose stimulation. Varying demands and available nutrients during development produce changes in the local connectivity of β cells in an islet. We showed in earlier work that graph theory provides a framework for the quantification of the seemingly stochastic cyto-architecture of β cells in an islet...
April 11, 2016: Physical Biology
https://www.readbyqxmd.com/read/27040917/multi-terminal-josephson-junctions-as-topological-matter
#16
Roman-Pascal Riwar, Manuel Houzet, Julia S Meyer, Yuli V Nazarov
Topological materials and their unusual transport properties are now at the focus of modern experimental and theoretical research. Their topological properties arise from the bandstructure determined by the atomic composition of a material and as such are difficult to tune and naturally restricted to ≤3 dimensions. Here we demonstrate that n-terminal Josephson junctions with conventional superconductors may provide novel realizations of topology in n-1 dimensions, which have similarities, but also marked differences with existing 2D or 3D topological materials...
2016: Nature Communications
https://www.readbyqxmd.com/read/26929366/dynamics-inside-the-cancer-cell-attractor-reveal-cell-heterogeneity-limits-of-stability-and-escape
#17
Qin Li, Anders Wennborg, Erik Aurell, Erez Dekel, Jie-Zhi Zou, Yuting Xu, Sui Huang, Ingemar Ernberg
The observed intercellular heterogeneity within a clonal cell population can be mapped as dynamical states clustered around an attractor point in gene expression space, owing to a balance between homeostatic forces and stochastic fluctuations. These dynamics have led to the cancer cell attractor conceptual model, with implications for both carcinogenesis and new therapeutic concepts. Immortalized and malignant EBV-carrying B-cell lines were used to explore this model and characterize the detailed structure of cell attractors...
March 8, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/26902659/the-way-from-microscopic-many-particle-theory-to-macroscopic-hydrodynamics
#18
Rudolf Haussmann
Starting from the microscopic description of a normal fluid in terms of any kind of local interacting many-particle theory we present a well defined step by step procedure to derive the hydrodynamic equations for the macroscopic phenomena. We specify the densities of the conserved quantities as the relevant hydrodynamic variables and apply the methods of non-equilibrium statistical mechanics with projection operator techniques. As a result we obtain time-evolution equations for the hydrodynamic variables with three kinds of terms on the right-hand sides: reversible, dissipative and fluctuating terms...
March 23, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/26764789/neighborhoods-of-periodic-orbits-and-the-stationary-distribution-of-a-noisy-chaotic-system
#19
Jeffrey M Heninger, Domenico Lippolis, Predrag Cvitanović
The finest state-space resolution that can be achieved in a physical dynamical system is limited by the presence of noise. In the weak-noise approximation, the stochastic neighborhoods of deterministic periodic orbits can be computed from distributions stationary under the action of a local Fokker-Planck operator and its adjoint. We derive explicit formulas for widths of these distributions in the case of chaotic dynamics, when the periodic orbits are hyperbolic. The resulting neighborhoods form a basis for functions on the attractor...
December 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
https://www.readbyqxmd.com/read/26720924/complete-firing-rate-response-of-neurons-with-complex-intrinsic-dynamics
#20
Maximilian Puelma Touzel, Fred Wolf
The response of a neuronal population over a space of inputs depends on the intrinsic properties of its constituent neurons. Two main modes of single neuron dynamics-integration and resonance-have been distinguished. While resonator cell types exist in a variety of brain areas, few models incorporate this feature and fewer have investigated its effects. To understand better how a resonator's frequency preference emerges from its intrinsic dynamics and contributes to its local area's population firing rate dynamics, we analyze the dynamic gain of an analytically solvable two-degree of freedom neuron model...
December 2015: PLoS Computational Biology
keyword
keyword
12064
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"