Quantum and Thermal Fluctuations in Field Theory
Liao, Sen-Ben; Polonyi, Janos; Xu, Dapeng
1994-01-01
Blocking transformation is performed in quantum field theory at finite temperature. It is found that the manner temperature deforms the renormalized trajectories can be used to understand better the role played by the quantum fluctuations. In particular, it is conjectured that domain formation and mass parameter generation can be observed in theories without spontaneous symmetry breaking.
Quantitative theory of thermal fluctuations and disorder in the vortex ...
Indian Academy of Sciences (India)
thermal fluctuations will effectively reduce the effects of disorder and melt the vor- tex lattice. As a result the H–T phase diagram .... of the vortex lattice by disorder was solved with the vortex matter being in the replica symmetry broken (RSB) phase and it ..... E Zeldov, private communication. [19] U Divakar, A J Drew, S L Lee, ...
Quantitative theory of thermal fluctuations and disorder in the vortex ...
Indian Academy of Sciences (India)
Based on this picture, a quantitative theory of vortex melting and glass transition in Type II superconductors in the framework of Ginzburg-Landau approach is presented. The melting line location is determined and magnetization and specific heat jumps are calculated. The point-like disorder shifts the line downwards and ...
Thermal fluctuations in pinned elastic systems: field theory of rare events and droplets
Balents, Leon; Le Doussal, Pierre
2005-01-01
Using the functional renormalization group (FRG) we study the thermal fluctuations of elastic objects (displacement field u, internal dimension d) pinned by a random potential at low temperature T, as prototypes for glasses. A challenge is how the field theory can describe both typical (minimum energy T = 0) configurations, as well as thermal averages which, at any non-zero T as in the phenomenological droplet picture, are dominated by rare degeneracies between low lying minima. We show that this occurs through an essentially non-perturbative thermal boundary layer (TBL) in the (running) effective action Γ [ u] at T > 0 for which we find a consistent scaling ansatz to all orders. The TBL describes how temperature smoothes the singularities of the T = 0 theory and contains the physics of rare thermal excitations (droplets). The formal structure of this TBL, which involves all cumulants of the coarse grained disorder, is first explored around d = 4 using a one-loop Wilson RG. Next, a more systematic exact RG (ERG) method is employed, and first tested on d = 0 models where it can be pushed quite far. There we obtain precise relations between TBL quantities and droplet probabilities (those are constrained by exact identities which are then checked against recent exact results). Our analysis is then extended to higher d, where we illustrate how the TBL scaling remains consistent to all orders in the ERG and how droplet picture results can be retrieved. Since correlations are determined deep in the TBL (by derivatives of Γ [ u] at u = 0), it remains to be understood (in any d) how they can be retrieved (as u = 0 + limits in the non-analytic T = 0 effective action), i.e., how to recover a T = 0 critical theory. This formidable "matching problem" is solved in detail for d = 0, N = 1 by studying the (partial) TBL structure of higher cumulants when points are brought together. We thereby obtain the β-function at T = 0, all ambiguities removed, displayed here up to four
Yamanishi, Masamichi
2012-12-17
Intrinsic linewidth formula modified by taking account of fluctuation-dissipation balance for thermal photons in a THz quantum-cascade laser (QCL) is exhibited. The linewidth formula based on the model that counts explicitly the influence of noisy stimulated emissions due to thermal photons existing inside the laser cavity interprets experimental results on intrinsic linewidth, ~91.1 Hz reported recently with a 2.5 THz bound-to-continuum QCL. The line-broadening induced by thermal photons is estimated to be ~22.4 Hz, i.e., 34% broadening. The modified linewidth formula is utilized as a bench mark in engineering of THz thermal photons inside laser cavities.
Effect of thermal fluctuations on a charged dilatonic black Saturn
Directory of Open Access Journals (Sweden)
Behnam Pourhassan
2016-04-01
Full Text Available In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.
Effect of thermal fluctuations on a charged dilatonic black Saturn
Energy Technology Data Exchange (ETDEWEB)
Pourhassan, Behnam, E-mail: b.pourhassan@du.ac.ir [School of Physics, Damghan University, Damghan (Iran, Islamic Republic of); Faizal, Mir, E-mail: f2mir@uwaterloo.ca [Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)
2016-04-10
In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.
Effect of Thermal Fluctuations on a Charged Dilatonic Black Saturn
Pourhassan, Behnam
2016-01-01
In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.
A theory of fluctuations in plasmas
Felderhof, B.U.
A theory of thermal fluctuations in plasmas is developed based on a probability ensemble for one-particle distribution functions ƒ(r, ν). The probability for a specific ƒ(r, ν) is obtained from the canonical ensemble with the aid of the continuum approximation. Subsequently the probability
Quantum fluctuations from thermal fluctuations in Jacobson formalism
Energy Technology Data Exchange (ETDEWEB)
Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Ashour, Amani; Alcheikh, Mohammad [Damascus University, Mathematics Department, Faculty of Science, Damascus (Syrian Arab Republic); Alasfar, Lina [Universite Clermont Auvergne, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France); Alsaleh, Salwa; Mahroussah, Ahmed [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia)
2017-09-15
In the Jacobson formalism general relativity is obtained from thermodynamics. This is done by using the Bekenstein-Hawking entropy-area relation. However, as a black hole gets smaller, its temperature will increase. This will cause the thermal fluctuations to also increase, and these will in turn correct the Bekenstein-Hawking entropy-area relation. Furthermore, with the reduction in the size of the black hole, quantum effects will also start to dominate. Just as the general relativity can be obtained from thermodynamics in the Jacobson formalism, we propose that the quantum fluctuations to the geometry can be obtained from thermal fluctuations. (orig.)
Fluctuation theory of luminance and chromaticity discrimination
Bouman, M.A.; Vos, J.J.; Walraven, P.L.
1963-01-01
An attempt has been made to describe brightness and color discrimination in the framework of a fluctuation theory. The fluctuation theory states that a difference between two stimuli will be just noticeable if it exceeds, by some factor, the average of the fluctuations in the stimuli. If the
Thermal Fluctuations in Electroweak Phase Transition
Shiromizu, T.; Morikawa, M.; Yokoyama, J.
1995-11-01
We estimate the amplitude of thermal fluctuations by calculating the typical size of subcritical bubbles in cosmological electroweak phase transition and show that this thermal fluctuation effect drastically changes dynamics of the phase transition from the ordinary first order type with supercooling. From this fact, we conclude that the standard electroweak baryogenesis scenario associated with such a first order transition does not work in the minimal standard model in certain conditions.
Boley, Bruno A
1997-01-01
Highly regarded text presents detailed discussion of fundamental aspects of theory, background, problems with detailed solutions. Basics of thermoelasticity, heat transfer theory, thermal stress analysis, more. 1985 edition.
Noisy zigzag transition, fluctuations, and thermal bifurcation threshold
Delfau, Jean-Baptiste; Coste, Christophe; Saint Jean, Michel
2013-06-01
We study the zigzag transition in a system of particles with screened electrostatic interaction, submitted to a thermal noise. At finite temperature, this configurational phase transition is an example of noisy supercritical pitchfork bifurcation. The measurements of transverse fluctuations allow a complete description of the bifurcation region, which takes place between the deterministic threshold and a thermal threshold beyond which thermal fluctuations do not allow the system to flip between the symmetric zigzag configurations. We show that a divergence of the saturation time for the transverse fluctuations allows a precise and unambiguous definition of this thermal threshold. Its evolution with the temperature is shown to be in good agreement with theoretical predictions from noisy bifurcation theory.
Molecular thermodynamics using fluctuation solution theory
DEFF Research Database (Denmark)
Ellegaard, Martin Dela
to relevant experimental data is limited. This thesis addresses the issue of generating and using simple thermodynamic models within a rigorous statistical mechanical framework, the so-called fluctuation solution theory, from which relations connecting properties and phase equilibria can be obtained....... The framework relates thermodynamic variables to molecular pair correlation functions of liquid mixtures. In this thesis, application of the framework is illustrated using two approaches: 1. Solubilities of solid solutes in mixed solvent systems are determined from fluctuation solution theory application...
Spin-fluctuation theory beyond Gaussian approximation
Energy Technology Data Exchange (ETDEWEB)
Melnikov, N B [Moscow State University, 119992 Moscow (Russian Federation); Reser, B I; Grebennikov, V I, E-mail: melnikov@cs.msu.s, E-mail: reser@imp.uran.r, E-mail: greben@imp.uran.r [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation)
2010-05-14
A characteristic feature of the Gaussian approximation in the functional-integral approach to the spin-fluctuation theory is the jump phase transition to the paramagnetic state. We eliminate the jump and obtain a continuous second-order phase transition by taking into account high-order terms in the expansion of the free energy in powers of the fluctuating exchange field. The third-order term of the free energy renormalizes the mean field, and the fourth-order term, responsible for the interaction of the fluctuations, renormalizes the spin susceptibility. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar.
Single molecule detection, thermal fluctuation and life
YANAGIDA, Toshio; ISHII, Yoshiharu
2017-01-01
Single molecule detection has contributed to our understanding of the unique mechanisms of life. Unlike artificial man-made machines, biological molecular machines integrate thermal noises rather than avoid them. For example, single molecule detection has demonstrated that myosin motors undergo biased Brownian motion for stepwise movement and that single protein molecules spontaneously change their conformation, for switching to interactions with other proteins, in response to thermal fluctuation. Thus, molecular machines have flexibility and efficiency not seen in artificial machines. PMID:28190869
Transformational fluctuation electrodynamics: application to thermal radiation illusion.
Alwakil, Ahmed; Zerrad, Myriam; Bellieud, Michel; Veynante, Denis; Enguehard, Franck; Rolland, Nathalie; Volz, Sebastian; Amra, Claude
2017-07-24
Thermal radiation is a universal property for all objects with temperatures above 0K. Every object with a specific shape and emissivity has its own thermal radiation signature; such signature allows the object to be detected and recognized which can be an undesirable situation. In this paper, we apply transformation optics theory to a thermal radiation problem to develop an electromagnetic illusion by controlling the thermal radiation signature of a given object. Starting from the fluctuation dissipation theorem where thermally fluctuating sources are related to the radiative losses, we demonstrate that it is possible for objects residing in two spaces, virtual and physical, to have the same thermal radiation signature if the complex permittivities and permeabilities satisfy the standard space transformations. We emphasize the invariance of the fluctuation electrodynamics physics under transformation, and show how this result allows the mimicking in thermal radiation. We illustrate the concept using the illusion paradigm in the two-dimensional space and a numerical calculation validates all predictions. Finally, we discuss limitations and extensions of the proposed technique.
Extended dynamic spin-fluctuation theory of metallic magnetism.
Melnikov, N B; Reser, B I; Grebennikov, V I
2011-07-13
A dynamic spin-fluctuation theory that directly takes into account nonlocality of thermal spin fluctuations and their mode-mode interactions is developed. The Gaussian approximation in the theory is improved by a self-consistent renormalization of the mean field and spin susceptibility due to the third-and fourth-order terms of the free energy, respectively. This eliminates the fictitious first-order phase transition, which is typical for the Gaussian approximation, and yields a proper second-order phase transition. The effect of nonlocal spin correlations is enhanced by taking into account uniform fluctuations in the single-site mean Green function. Explicit computational formulae for basic magnetic characteristics are obtained. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar. Almost full agreement with experiment is achieved for the magnetization, Curie temperature, and local and effective magnetic moments.
Extended dynamic spin-fluctuation theory of metallic magnetism
Energy Technology Data Exchange (ETDEWEB)
Melnikov, N B [Moscow State University, Moscow 119991 (Russian Federation); Reser, B I; Grebennikov, V I, E-mail: melnikov@cs.msu.su, E-mail: reser@imp.uran.ru, E-mail: greben@imp.uran.ru [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation)
2011-07-13
A dynamic spin-fluctuation theory that directly takes into account nonlocality of thermal spin fluctuations and their mode-mode interactions is developed. The Gaussian approximation in the theory is improved by a self-consistent renormalization of the mean field and spin susceptibility due to the third- and fourth-order terms of the free energy, respectively. This eliminates the fictitious first-order phase transition, which is typical for the Gaussian approximation, and yields a proper second-order phase transition. The effect of nonlocal spin correlations is enhanced by taking into account uniform fluctuations in the single-site mean Green function. Explicit computational formulae for basic magnetic characteristics are obtained. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar. Almost full agreement with experiment is achieved for the magnetization, Curie temperature, and local and effective magnetic moments.
Fluctuating Asymmetry: Methods, Theory, and Applications
Directory of Open Access Journals (Sweden)
John H. Graham
2010-03-01
Full Text Available Fluctuating asymmetry consists of random deviations from perfect symmetry in populations of organisms. It is a measure of developmental noise, which reflects a population’s average state of adaptation and coadaptation. Moreover, it increases under both environmental and genetic stress, though responses are often inconsistent. Researchers base studies of fluctuating asymmetry upon deviations from bilateral, radial, rotational, dihedral, translational, helical, and fractal symmetries. Here, we review old and new methods of measuring fluctuating asymmetry, including measures of dispersion, landmark methods for shape asymmetry, and continuous symmetry measures. We also review the theory, developmental origins, and applications of fluctuating asymmetry, and attempt to explain conflicting results. In the process, we present examples from the literature, and from our own research at “Evolution Canyon” and elsewhere.
Whistler-cyclotron spontaneous fluctuations. A proxy to identify thermal and non-thermal electrons?
Moya, P. S.; López, R. A.; Navarro, R.; Vinas, A. F.; Munoz, V.; Araneda, J. A.; Valdivia, J. A.
2016-12-01
Observed electron velocity distributions in the space plasmas exhibit a variety of non-thermal features which deviate from thermal equilibrium, in the form of temperature anisotropies, suprathermal tails, and field aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations. For example, the whistler cyclotron waves at electron scales. Here we present a comparative analysis of these fluctuations based upon anisotropic plasma modeled with thermal and non-thermal particle distributions. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic magnetized electron-proton plasma modeled with bi-Maxwellian and kappa-like distributions. Dispersion analysis and stability thresholds are derived for these non-thermal distributions and compared with similar results obtained from PIC simulations using plasma and field parameters relevant to space nearly collisionless environments. Our results indicate that there is a strong dependence between the shape of the velocity distribution function and the spontaneous magnetic fluctuations wave spectrum. This feature may be used proxy to identify the nature of electron populations in space plasmas when high resolution particle instruments are not available.
Simulation of electromagnetic fluctuations in thermal magnetized plasma
López, Rodrigo A.; Yoon, Peter H.
2017-11-01
The present paper carries out a particle-in-cell (PIC) simulation in order to validate the recently formulated theory of electromagnetic fluctuations emitted spontaneously in thermal magnetized plasmas (Yoon and López 2017 Phys. Plasmas 24 022117). Numerical plots of theoretically constructed fluctuation spectra and computer simulated fluctuation spectra are compared. While the two results produce an overall favorable agreement for subluminous regime in angular frequency versus wave number space, namely, the domain characterized by phase speed less than the speed of light in vacuo, the present PIC simulation also shows that fluctuation spectra are highly enhanced in the close vicinity of linear eigenmodes, which includes superluminal range that does not satisfy the linear cyclotron wave-particle resonance condition. Since the theory of electromagnetic spontaneous emission, which is based upon linear plasma response and linear wave-particle resonant interactions, strictly forbids emissions in such a regime, the PIC code simulation can only be understood in terms of nonlinear wave-particle interaction. This calls for nonlinear generalization of the spontaneous emission theory.
Nonlinear dynamical effects on reaction rates in thermally fluctuating environments.
Kawai, Shinnosuke; Komatsuzaki, Tamiki
2010-07-21
A framework to calculate the rate constants of condensed phase chemical reactions of manybody systems is presented without relying on the concept of transition state. The theory is based on a framework we developed recently adopting a multidimensional underdamped Langevin equation in the region of a rank-one saddle. The theory provides a reaction coordinate expressed as an analytical nonlinear functional of the position coordinates and velocities of the system (solute), the friction constants, and the random force of the environment (solvent). Up to moderately high temperature, the sign of the reaction coordinate can determine the final destination of the reaction in a thermally fluctuating media, irrespective of what values the other (nonreactive) coordinates may take. In this paper, it is shown that the reaction probability is analytically derived as the probability of the reaction coordinate being positive, and that the integration with the Boltzmann distribution of the initial conditions leads to the exact reaction rate constant when the local equilibrium holds and the quantum effect is negligible. Because of analytical nature of the theory taking into account all nonlinear effects and their combination with fluctuation and dissipation, the theory naturally provides us with the firm mathematical foundation of the origin of the reactivity of the reaction in a fluctuating media.
Thermal fluctuations in a hyperscaling-violation background
Energy Technology Data Exchange (ETDEWEB)
Pourhassan, Behnam [Damghan University, School of Physics, Damghan (Iran, Islamic Republic of); Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Upadhyay, Sudhaker [Indian Institute of Technology Kharagpur, Centre for Theoretical Studies, Kharagpur (India); Al Asfar, Lina [Universite Blaise Pascal, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France)
2017-08-15
In this paper, we study the effect of thermal fluctuations on the thermodynamics of a black geometry with hyperscaling violation. These thermal fluctuations in the thermodynamics of this system are produced from quantum corrections of geometry describing this system. We discuss the stability of this system using specific heat and the entire Hessian matrix of the free energy. We will analyze the effects of thermal fluctuations on the stability of this system. We also analyze the effects of thermal fluctuations on the criticality of the hyperscaling-violation background. (orig.)
Fluctuation Solution Theory Properties from Molecular Simulation
DEFF Research Database (Denmark)
Abildskov, Jens; Wedberg, R.; O’Connell, John P.
2013-01-01
The thermodynamic properties obtained in the Fluctuation Solution Theory are based on spatial integrals of molecular TCFs between component pairs in the mixture. Molecular simulation, via either MD or MC calculations, can yield these correlation functions for model inter- and intramolecular...... potential functions. However, system-size limitations and statistical noise cause uncertainties in the functions at long range, and thus uncertainties or errors in the integrals. A number of methods such as truncation, distance shifting, long-range modeling, transforms, DCF matching, finite-size scaling...
Queues and Lévy fluctuation theory
Dębicki, Krzysztof
2015-01-01
The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.
Energy Technology Data Exchange (ETDEWEB)
Lei, Huan; Baker, Nathan A.; Wu, Lei; Schenter, Gregory K.; Mundy, Christopher J.; Tartakovsky, Alexandre M.
2016-08-05
Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a novel multiphase smoothed dissipative particle dynamics model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension, we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semi-analytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models the dynamic processes, such as bubble coalescence and capillary spectra across the interface.
Entropic Fluctuations in Thermally Driven Harmonic Networks
Jakšić, V.; Pillet, C.-A.; Shirikyan, A.
2017-02-01
We consider a general network of harmonic oscillators driven out of thermal equilibrium by coupling to several heat reservoirs at different temperatures. The action of the reservoirs is implemented by Langevin forces. Assuming the existence and uniqueness of the steady state of the resulting process, we construct a canonical entropy production functional S^t which satisfies the Gallavotti-Cohen fluctuation theorem. More precisely, we prove that there exists κ _c>1/2 such that the cumulant generating function of S^t has a large-time limit e(α ) which is finite on a closed interval [1/2-κ _c,1/2+κ _c], infinite on its complement and satisfies the Gallavotti-Cohen symmetry e(1-α )=e(α ) for all α in R. Moreover, we show that e(α ) is essentially smooth, i.e., that e'(α )→ ∓ ∞ as α → 1/2 ∓ κ _c. It follows from the Gärtner-Ellis theorem that S^t satisfies a global large deviation principle with a rate function I( s) obeying the Gallavotti-Cohen fluctuation relation I(-s)-I(s)=s for all sin R. We also consider perturbations of S^t by quadratic boundary terms and prove that they satisfy extended fluctuation relations, i.e., a global large deviation principle with a rate function that typically differs from I( s) outside a finite interval. This applies to various physically relevant functionals and, in particular, to the heat dissipation rate of the network. Our approach relies on the properties of the maximal solution of a one-parameter family of algebraic matrix Riccati equations. It turns out that the limiting cumulant generating functions of S^t and its perturbations can be computed in terms of spectral data of a Hamiltonian matrix depending on the harmonic potential of the network and the parameters of the Langevin reservoirs. This approach is well adapted to both analytical and numerical investigations.
Magnetic Alfvén-Cyclotron Fluctuations of Anisotropic Non-Thermal Plasmas
Navarro, R.; Munoz, V.; Araneda, J. A.; Vinas, A. F.; Moya, P. S.; Valdivia, J. A.
2014-12-01
Remote and in situ observations in the solar wind show that ion and electron velocity distributions persistently present deviations from thermal equilibrium. Ion anisotropies seem to be constrained by instability thresholds which are in agreement with linear kinetic theory. For plasma states below these instability thresholds, the quasi-stable solar wind plasma sustains a small but detectable level of magnetic fluctuation power. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we study electromagnetic fluctuations propagating along a background magnetic field in a plasma composed of thermal and suprathermal protons and electrons via the fluctuation-dissipation theorem. The total fluctuating magnetic power is estimated in a proton temperature anisotropy-beta diagram for three different families of proton distribution functions, which can be compared to a number of recent measurements in the solar wind.
Quantum fluctuations and thermal dissipation in higher derivative gravity
Directory of Open Access Journals (Sweden)
Dibakar Roychowdhury
2015-08-01
Full Text Available In this paper, based on the AdS2/CFT1 prescription, we explore the low frequency behavior of quantum two point functions for a special class of strongly coupled CFTs in one dimension whose dual gravitational counterpart consists of extremal black hole solutions in higher derivative theories of gravity defined over an asymptotically AdS spacetime. The quantum critical points thus described are supposed to correspond to a very large value of the dynamic exponent (z→∞. In our analysis, we find that quantum fluctuations are enhanced due to the higher derivative corrections in the bulk which in turn increases the possibility of quantum phase transition near the critical point. On the field theory side, such higher derivative effects would stand for the corrections appearing due to the finite coupling in the gauge theory. Finally, we compute the coefficient of thermal diffusion at finite coupling corresponding to Gauss Bonnet corrected charged Lifshitz black holes in the bulk. We observe an important crossover corresponding to z=5 fixed point.
Energy Technology Data Exchange (ETDEWEB)
Gibert, M
2007-10-15
In this study we investigate the phenomenon of thermal turbulent convection in new and unprecedented ways. The first system we studied experimentally is an infinite vertical channel, where a constant vertical mean gradient of temperature exists. Inside this channel the average mass flux is null. The results obtained from our measurements reveal that the flow is mainly inertial; indeed the dissipative coefficients (here the viscosity) play a role only to define a coherence length L. This length is the distance over which the thermal plumes can be considered as 'free falling' objects. The horizontal transport, of heat and momentum, is entirely due to fluctuations. The associated 'mixing length' is small compared to the channel width. In the other hand, the vertical heat transport is due to coherent structures: the heat plumes. Those objects were also investigated in a Lagrangian study of the flow in the bulk of a Rayleigh-Benard cell. The probe, which has the same density as the fluid used in this experiment, is a sphere of 2 cm in diameter with embarked thermometers and radio-emitter. The heat plumes transport it, which allows a statistical study of such objects. (author)
Moya, P. S.; Vinas, A. F.; Navarro, R.; Araneda, J. A.
2014-12-01
Observed electron velocity distributions in the solar wind exhibit a variety of non-thermal features which deviate from thermal equilibrium, in the form of temperature anisotropies, suprathermal tails, and field aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations as for example the whistler cyclotron waves at electron scales. Here we present a comparative analysis of these fluctuations based upon anisotropic plasma modeled with thermal and non-thermal particle distributions. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic thermal bi-Maxwellian and non-thermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these non-thermal distributions and compared with similar results obtained from PIC simulations using plasma and field parameters relevant to the solar wind environments. Our results indicate that there is a strong dependence between the shape of the velocity distribution function and the topological regions in the frequency-wave number plane in which the spontaneous fluctuations emerge. In the case of non-thermal plasmas there is an enhancement of the fluctuations level due to the effective higher-temperature effects and the excess of suprathermal particles. This feature may be used proxy to identify the nature of electron populations in space plasmas when high resolution particle instruments are not available.
Planck's Radiation Law: Thermal Excitations of Vacuum Induced Fluctuations
Directory of Open Access Journals (Sweden)
Ogiba F.
2015-04-01
Full Text Available The second Planck’s radiation law is derived considering that “resonators” induced by the vacuum absorb thermal excitations as additional fluctuations. The maximum energy transfer, as required by the maximum entropy equilibrium, occurs when the frequencies of these two kind of vibrations are equal. The motion resembles that of the coherent states of the quantum oscillator, as originally pointed by Schrödinger [1]. The resulting variance, due to random phases, coincides with that used by Einstein to reproduce the first Planck’s radiation law from his thermal fluctuation equation [2].
Classical fluctuations in quantum field theory
Morikawa, M.
The question as to whether quantum fluctuations can induce the spontaneous breaking of translational invariance (SBTI) in the extreme cosmic expansion that occurs during any type of inflation is considered. Attention is given to the unstable field, thermofield dynamic, and cosmic anisotropic relaxation quantum systems, defining the appropriate order parameters for each and discussing their properties. A mechanism for SBTI is presented which possesses both generality and applicability to various problems; a complex effective potential can, for example, be obtained for a nonconvex potential, so that a random force arises and stochastically agitates order parameters.
Transformational fluctuation electrodynamics: application to thermal radiation illusion
Alwakil, Ahmed; Zerrad, Myriam; Bellieud, Michel; Veynante, Denis; Enguehard, Franck; Rolland, Nathalie; Volz, Sebastian; Amra, Claude
2017-01-01
International audience; Thermal radiation is a universal property for all objects with temperatures above 0K. Every object with a specific shape and emissivity has its own thermal radiation signature; such signature allows the object to be detected and recognized which can be an undesirable situation. In this paper, we apply transformation optics theory to a thermal radiation problem to develop an electromagnetic illusion by controlling the thermal radiation signature of a given object. Start...
Critical thermal limits affected differently by developmental and adult thermal fluctuations.
Salachan, Paul Vinu; Sørensen, Jesper Givskov
2017-12-01
Means and variances of the environmental thermal regime play an important role in determining the fitness of terrestrial ectotherms. Adaptive phenotypic responses induced by heterogeneous temperatures have been shown to be mediated by molecular pathways independent of the classic heat shock responses; however, an in-depth understanding of plasticity induced by fluctuating temperatures is still lacking. We investigated high and low temperature acclimation induced by fluctuating thermal regimes at two different mean temperatures, at two different amplitudes of fluctuation and across the developmental and adult life stages of Drosophila melanogaster For developmental acclimation, we found mildly detrimental effects of high-amplitude fluctuations for critical thermal minima, while the critical thermal maxima showed a beneficial response to higher amplitude fluctuations. For adult acclimation involving shifts between fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly, we also found that the effect of fluctuations at any life stage was gradually lost with prolonged adult maintenance, suggesting a more prominent effect of fluctuations during developmental compared with adult acclimation in D.melanogaster. © 2017. Published by The Company of Biologists Ltd.
Curvature of fluctuation geometry and its implications on Riemannian fluctuation theory
Velazquez, L.
2013-08-01
Fluctuation geometry was recently proposed as a counterpart approach of the Riemannian geometry of inference theory (widely known as information geometry). This theory describes the geometric features of the statistical manifold {M} of random events that are described by a family of continuous distributions dp(x|θ). A main goal of this work is to clarify the statistical relevance of the Levi-Civita curvature tensor Rijkl(x|θ) of the statistical manifold {M}. For this purpose, the notion of irreducible statistical correlations is introduced. Specifically, a distribution dp(x|θ) exhibits irreducible statistical correlations if every distribution dp(\\check{x}|\\theta ) obtained from dp(x|θ) by considering a coordinate change \\check{x}=\\phi (x) cannot be factorized into independent distributions as dp(\\check{x}|\\theta )=\\prod _{i}dp^{(i)}(\\check{x}^{i}|\\theta ). It is shown that the curvature tensor Rijkl(x|θ) arises as a direct indicator about the existence of irreducible statistical correlations. Moreover, the curvature scalar R(x|θ) allows us to introduce a criterium for the applicability of the Gaussian approximation of a given distribution function. This type of asymptotic result is obtained in the framework of the second-order geometric expansion of the distribution family dp(x|θ), which appears as a counterpart development of the high-order asymptotic theory of statistical estimation. In physics, fluctuation geometry represents the mathematical apparatus of a Riemannian extension for Einstein’s fluctuation theory of statistical mechanics. Some exact results of fluctuation geometry are now employed to derive the invariant fluctuation theorems. Moreover, the curvature scalar allows us to express some asymptotic formulae that account for the system fluctuating behavior beyond the Gaussian approximation, e.g.: it appears as a second-order correction of the Legendre transformation between thermodynamic potentials, P(\\theta )=\\theta _{i
Thermodynamic Models from Fluctuation Solution Theory Analysis of Molecular Simulations
DEFF Research Database (Denmark)
Christensen, Steen; Peters, Günther H.j.; Hansen, Flemming Yssing
2007-01-01
Fluctuation solution theory (FST) is employed to analyze results of molecular dynamics (MD) simulations of liquid mixtures. The objective is to generate parameters for macroscopic GE-models, here the modified Margules model. We present a strategy for choosing the number of parameters included...
Critical thermal limits affected differently by developmental and adult thermal fluctuations
DEFF Research Database (Denmark)
Salachan, Paul Vinu; Sørensen, Jesper Givskov
2017-01-01
Means and variances of the environmental thermal regime play an important role in determining the fitness of terrestrial ectotherms. Adaptive phenotypic responses induced by heterogeneous temperatures have been shown to be mediated by molecular pathways independent of the classic heat shock...... responses, however, an in-depth understanding of plasticity induced by fluctuating temperatures is still lacking. We investigated high and low temperature acclimation induced by fluctuating thermal regimes at two different mean temperatures, at two different amplitudes of fluctuation and across...... fluctuating and constant regimes, cold tolerance was shown to be dictated by developmental temperature conditions irrespective of the adult treatments, while the acquired heat tolerance was readily lost when flies developed at fluctuating temperature were shifted to a constant regime as adults. Interestingly...
Theory of temporal fluctuations in isolated quantum systems
Venuti, Lorenzo Campos; Zanardi, Paolo
2015-05-01
When an isolated quantum system is driven out of equilibrium, expectation values of general observables start oscillating in time. This paper reviews the general theory of such temporal fluctuations. We first survey some results on the strength of such temporal fluctuations. For example temporal fluctuations are exponentially small in the system's volume for generic systems whereas they fall-off algebraically in integrable systems. We then concentrate on the so-called quench scenario where the system is driven out-of-equilibrium under the application of a sudden perturbation. For sufficiently small perturbations, temporal fluctuations of physical observables can be characterized in full generality and can be used as an effective tool to probe quantum criticality of the underlying model. In the off-critical region the distribution becomes Gaussian. Close to criticality the distribution becomes a universal function uniquely characterized by a single critical exponent, that we compute explicitly. This contrasts standard equilibrium quantum fluctuations for which the critical distribution depends on a numerable set of critical coefficients and is known only for limited examples. The possibility of using temporal fluctuations to determine pseudo-critical boundaries in optical lattice experiments is further reviewed.
Rectifying thermal fluctuations: Minimal pumping and Maxwell's demon
Mandal, Dibyendu
Molecular complexes with movable components form the basis of nanoscale machines. Their inherent stochastic nature makes it a challenge to generate any controllable movement. Rather than fighting these fluctuations, one can utilize them by the periodic modulation of system parameters, or stochastic pumping. For the no-pumping theorem (NPT), which establishes minimal conditions for directed pumping, we present a simplified proof using an elementary graph theoretical construction. Motivated by recent experiments, we propose a new class of "hybrid" models combining elements of both the purely discrete and purely continuous descriptions prevalent in the field. We formulate the NPT in this hybrid framework to give a detailed justification of the original experiment observation. We also present an extension of the NPT to open stochastic systems. Next we consider the paradox of "Maxwell's demon," an imaginary intelligent being that rectifies thermal fluctuations in a manner that seems to violate the second law of thermodynamics. We present two exactly solvable, autonomous models that can reproduce the actions of the demon. Of necessity, both of these models write information on a memory device as part of their operation. By exposing their explicit, transparent mechanisms, our models offer simple paradigms to investigate the autonomous rectification of thermal fluctuations and the thermodynamics of information processing.
Quantum and thermal fluctuations in a Raman spin-orbit-coupled Bose gas
Chen, Xiao-Long; Liu, Xia-Ji; Hu, Hui
2017-07-01
We theoretically study a three-dimensional weakly interacting Bose gas with Raman-induced spin-orbit coupling at finite temperature. By employing a generalized Hartree-Fock-Bogoliubov theory with Popov approximation, we determine a complete finite-temperature phase diagram of three exotic condensation phases (i.e., the stripe, plane-wave, and zero-momentum phases), against both quantum and thermal fluctuations. We find that the plane-wave phase is significantly broadened by thermal fluctuations. The phonon mode and sound velocity at the transition from the plane-wave phase to the zero-momentum phase are thoughtfully analyzed. At zero temperature, we find that quantum fluctuations open an unexpected gap in sound velocity at the phase transition, in stark contrast to the previous theoretical prediction of a vanishing sound velocity. At finite temperature, thermal fluctuations continue to significantly enlarge the gap, and simultaneously shift the critical minimum. For a Bose gas of 87Rb atoms at the typical experimental temperature, T =0.3 T0 , where T0 is the critical temperature of an ideal Bose gas without spin-orbit coupling, our results of gap opening and critical minimum shifting in the sound velocity are qualitatively consistent with the recent experimental observation [Ji et al., Phys. Rev. Lett. 114, 105301 (2015), 10.1103/PhysRevLett.114.105301].
General framework for fluctuating dynamic density functional theory
Durán-Olivencia, Miguel A.; Yatsyshin, Peter; Goddard, Benjamin D.; Kalliadasis, Serafim
2017-12-01
We introduce a versatile bottom-up derivation of a formal theoretical framework to describe (passive) soft-matter systems out of equilibrium subject to fluctuations. We provide a unique connection between the constituent-particle dynamics of real systems and the time evolution equation of their measurable (coarse-grained) quantities, such as local density and velocity. The starting point is the full Hamiltonian description of a system of colloidal particles immersed in a fluid of identical bath particles. Then, we average out the bath via Zwanzig’s projection-operator techniques and obtain the stochastic Langevin equations governing the colloidal-particle dynamics. Introducing the appropriate definition of the local number and momentum density fields yields a generalisation of the Dean–Kawasaki (DK) model, which resembles the stochastic Navier–Stokes description of a fluid. Nevertheless, the DK equation still contains all the microscopic information and, for that reason, does not represent the dynamical law of observable quantities. We address this controversial feature of the DK description by carrying out a nonequilibrium ensemble average. Adopting a natural decomposition into local-equilibrium and nonequilibrium contribution, where the former is related to a generalised version of the canonical distribution, we finally obtain the fluctuating-hydrodynamic equation governing the time-evolution of the mesoscopic density and momentum fields. Along the way, we outline the connection between the ad hoc energy functional introduced in previous DK derivations and the free-energy functional from classical density-functional theory. The resultant equation has the structure of a dynamical density-functional theory (DDFT) with an additional fluctuating force coming from the random interactions with the bath. We show that our fluctuating DDFT formalism corresponds to a particular version of the fluctuating Navier–Stokes equations, originally derived by Landau and
Abkenar, Masoud; Gray, Thomas H.; Zaccone, Alessio
2017-04-01
Theories that are used to extract energy-landscape information from single-molecule pulling experiments in biophysics are all invariably based on Kramers' theory of the thermally activated escape rate from a potential well. As is well known, this theory recovers the Arrhenius dependence of the rate on the barrier energy and crucially relies on the assumption that the barrier energy is much larger than kBT (limit of comparatively low thermal fluctuations). As was shown already in Dudko et al. [Phys. Rev. Lett. 96, 108101 (2006), 10.1103/PhysRevLett.96.108101], this approach leads to the unphysical prediction of dissociation time increasing with decreasing binding energy when the latter is lowered to values comparable to kBT (limit of large thermal fluctuations). We propose a theoretical framework (fully supported by numerical simulations) which amends Kramers' theory in this limit and use it to extract the dissociation rate from single-molecule experiments where now predictions are physically meaningful and in agreement with simulations over the whole range of applied forces (binding energies). These results are expected to be relevant for a large number of experimental settings in single-molecule biophysics.
Effects of thermal fluctuations on non-minimal regular magnetic black hole
Jawad, Abdul; Shahzad, M. Umair
2017-05-01
We analyze the effects of thermal fluctuations on a regular black hole (RBH) of the non-minimal Einstein-Yang-Mill theory with gauge field of magnetic Wu-Yang type and a cosmological constant. We consider the logarithmic corrected entropy in order to analyze the thermal fluctuations corresponding to non-minimal RBH thermodynamics. In this scenario, we develop various important thermodynamical quantities, such as entropy, pressure, specific heats, Gibb's free energy and Helmholtz free energy. We investigate the first law of thermodynamics in the presence of logarithmic corrected entropy and non-minimal RBH. We also discuss the stability of this RBH using various frameworks such as the γ factor (the ratio of heat capacities), phase transition, grand canonical ensemble and canonical ensemble. It is observed that the non-minimal RBH becomes globally and locally more stable if we increase the value of the cosmological constant.
Effects of thermal fluctuations on non-minimal regular magnetic black hole
Energy Technology Data Exchange (ETDEWEB)
Jawad, Abdul [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Shahzad, M.U. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); University of Central Punjab, CAMS, UCP Business School, Lahore (Pakistan)
2017-05-15
We analyze the effects of thermal fluctuations on a regular black hole (RBH) of the non-minimal Einstein-Yang-Mill theory with gauge field of magnetic Wu-Yang type and a cosmological constant. We consider the logarithmic corrected entropy in order to analyze the thermal fluctuations corresponding to non-minimal RBH thermodynamics. In this scenario, we develop various important thermodynamical quantities, such as entropy, pressure, specific heats, Gibb's free energy and Helmholtz free energy. We investigate the first law of thermodynamics in the presence of logarithmic corrected entropy and non-minimal RBH. We also discuss the stability of this RBH using various frameworks such as the γ factor (the ratio of heat capacities), phase transition, grand canonical ensemble and canonical ensemble. It is observed that the non-minimal RBH becomes globally and locally more stable if we increase the value of the cosmological constant. (orig.)
Heat Flux and Entropy Produced by Thermal Fluctuations
DEFF Research Database (Denmark)
Ciliberto, S.; Imparato, Alberto; Naert, A.
2013-01-01
We report an experimental and theoretical analysis of the energy exchanged between two conductors kept at different temperature and coupled by the electric thermal noise. Experimentally we determine, as functions of the temperature difference, the heat flux, the out-of-equilibrium variance......, and a conservation law for the fluctuating entropy, which we justify theoretically. The system is ruled by the same equations as two Brownian particles kept at different temperatures and coupled by an elastic force. Our results set strong constraints on the energy exchanged between coupled nanosystems held...
Molecular Thermodynamic Modeling of Fluctuation Solution Theory Properties
DEFF Research Database (Denmark)
O’Connell, John P.; Abildskov, Jens
2013-01-01
Fluctuation Solution Theory provides relationships between integrals of the molecular pair total and direct correlation functions and the pressure derivative of solution density, partial molar volumes, and composition derivatives of activity coefficients. For dense fluids, the integrals follow...... a relatively simple corresponding-states behavior even for complex systems, show welldefined relationships for infinite dilution properties in complex and near-critical systems, allow estimation of mixed-solvent solubilities of gases and pharmaceuticals, and can be expressed by simple perturbation models...
Ramifications of topology and thermal fluctuations in quasi-2D condensates
Roy, Arko; Angom, D.
2017-11-01
We explore the topological transformation of quasi-2D Bose–Einstein condensates of dilute atomic gases, and changes in the collective modes as the confining potential is modified from rotationally symmetric multiply connected to multiply connected with broken rotational symmetry and ultimately to a simply connected geometry. In particular, we show that the condensate density, and the non-condensate density arising from the quantum fluctuations, follow the transition in the geometry of the confining potential. The non-condensate density arising from the thermal fluctuations, in contrast, remain multiply connected when the thermal energy exceeds the maximum value in the basin of the confining potential. Otherwise, both the condensate and non-condensate densities become simply connected. The topology of the non-condensate densities is determined by the thermal energy, the repulsive interaction energy between atoms, and the trapping potential energy. In particular, the origin of the difference lies in the structure of the low-energy collective modes, which we examine using the Hartree–Fock–Bogoliubov formalism. We then use the Hartree–Fock–Bogoliubov theory with the Popov approximation to investigate the density and the momentum distribution associated with the thermal fluctuations.
Vinas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto; Araneda, Jamie A.
2014-01-01
Two fundamental challenging problems of laboratory and astrophysical plasmas are the understanding of the relaxation of a collisionless plasmas with nearly isotropic velocity distribution functions and the resultant state of nearly equipartition energy density with electromagnetic plasma turbulence. Here, we present the results of a study which shows the role that higher-order-modes play in limiting the electromagnetic whistler-like fluctuations in a thermal and non-thermal plasma. Our main results show that for a thermal plasma the magnetic fluctuations are confined by regions that are bounded by the least-damped higher order modes. We further show that the zone where the whistler-cyclotron normal modes merges the electromagnetic fluctuations shifts to longer wavelengths as the beta(sub e) increases. This merging zone has been interpreted as the beginning of the region where the whistler-cyclotron waves losses their identity and become heavily damped while merging with the fluctuations. Our results further indicate that in the case of nonthermal plasmas, the higher-order modes do not confine the fluctuations due to the effective higher-temperature effects and the excess of suprathermal plasma particles. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic bi-Maxwellian and Tsallis-kappa-like magnetized electron-proton plasma. Our results indicate that the spontaneously emitted electromagnetic fluctuations are in fact enhanced over these quasi modes suggesting that such modes play an important role in the emission and absorption of electromagnetic fluctuations in thermal or quasi-thermal plasmas.
The fluctuating ribosome: thermal molecular dynamics characterized by neutron scattering
Zaccai, Giuseppe; Natali, Francesca; Peters, Judith; Řihová, Martina; Zimmerman, Ella; Ollivier, J.; Combet, J.; Maurel, Marie-Christine; Bashan, Anat; Yonath, Ada
2016-11-01
Conformational changes associated with ribosome function have been identified by X-ray crystallography and cryo-electron microscopy. These methods, however, inform poorly on timescales. Neutron scattering is well adapted for direct measurements of thermal molecular dynamics, the ‘lubricant’ for the conformational fluctuations required for biological activity. The method was applied to compare water dynamics and conformational fluctuations in the 30 S and 50 S ribosomal subunits from Haloarcula marismortui, under high salt, stable conditions. Similar free and hydration water diffusion parameters are found for both subunits. With respect to the 50 S subunit, the 30 S is characterized by a softer force constant and larger mean square displacements (MSD), which would facilitate conformational adjustments required for messenger and transfer RNA binding. It has been shown previously that systems from mesophiles and extremophiles are adapted to have similar MSD under their respective physiological conditions. This suggests that the results presented are not specific to halophiles in high salt but a general property of ribosome dynamics under corresponding, active conditions. The current study opens new perspectives for neutron scattering characterization of component functional molecular dynamics within the ribosome.
Thermal performance curves under daily thermal fluctuation: A study in helmeted water toad tadpoles.
Bartheld, José L; Artacho, Paulina; Bacigalupe, Leonardo
2017-12-01
Most research in physiological ecology has focused on the effects of mean changes in temperature under the classic "hot vs cold" acclimation treatment; however, current evidence suggests that an increment in both the mean and variance of temperature could act synergistically to amplify the negative effects of global temperature increase and how it would affect fitness and performance-related traits in ectothermic organisms. We assessed the effects of acclimation to daily variance of temperature on thermal performance curves of swimming speed in helmeted water toad tadpoles (Calyptocephalella gayi). Acclimation treatments were 20°C ± 0.1 SD (constant) and 20°C ± 1.5 SD (fluctuating). We draw two key findings: first, tadpoles exposed to daily temperature fluctuation had reduced maximal performance (Zmax), and flattened thermal performance curves, thus supporting the "vertical shift or faster-slower" hypothesis, and suggesting that overall swimming performance would be lower through an examination of temperatures under more realistic and ecologically-relevant fluctuating regimens; second, there was significant interindividual variation in performance traits by means of significant repeatability estimates. Our present results suggest that the widespread use of constant acclimation temperatures in laboratory experiments to estimate thermal performance curves (TPCs) may lead to an overestimation of actual organismal performance. We encourage the use of temperature fluctuation acclimation treatments to better understand the variability of physiological traits, which predict ecological and evolutionary responses to global change. Copyright © 2017 Elsevier Ltd. All rights reserved.
Thermal physics kinetic theory and thermodynamics
Singh, Devraj; Yadav, Raja Ram
2016-01-01
THERMAL PHYSICS: Kinetic Theory and Thermodynamics is designed for undergraduate course in Thermal Physics and Thermodynamics. The book provides thorough understanding of the fundamental principles of the concepts in Thermal Physics. The book begins with kinetic theory, then moves on liquefaction, transport phenomena, the zeroth, first, second and third laws, thermodynamics relations and thermal conduction. The book concluded with radiation phenomenon. KEY FEATURES: * Include exercises * Short Answer Type Questions * Long Answer Type Questions * Numerical Problems * Multiple Choice Questions
Alternative theories of atmospheric telecommunications and low-frequency fluctuations
Frederiksen, Jorgen S.; Webster, Peter J.
1988-08-01
Observational studies have revealed a rich low-frequency structure in the atmosphere. A review of the theories, observations, and model studies of this low-frequency atmospheric variability is presented. On time scales of weeks or longer the atmosphere appears to possess distinct oscillatory behavior in well-defined and persistent "centers of action." This behavior is also an endemic feature of surrogate atmospheric data sets emerging from experiments with complicated climate models. Many theories have attempted to determine the dominant physical processes responsible for the low-frequency variance but have usually failed when compared carefully with observations. For example, simple linear steady state and Rossby wave dispersion theories have been used in an attempt to explain the observed global response to low-latitude perturbation. However, the observed structures of mature anomalies are often quite distinct from the vertical structures of disturbances predicted in these theories. Also, in general circulation and model studies, the sign of the nonlinear response is not simply related to the sign of the forcing as predicted by linear steady state theories. It is argued that the theories fail because either the full three-dimensional complexity of the basic state is not considered or its inherent instability structure is not recognized or is, in fact, ignored. It is shown that three-dimensional instability theory provides a natural generalization and marriage of the zonally averaged instability theory of Charney and Eady and the Rossby wave dispersion theory of Rossby and Yeh. As such, it provides a formalism which may be used to understand a wide variety of atmospheric fluctuations including the locations of eddy flux covariance maxima and storm tracks in both the tropics and extratropics and the generation of blocking, teleconnection patterns, and other quasi-stationary anomaly features. Attention is focused on two particular mechanisms within this formalism
Two problems in thermal field theory
Indian Academy of Sciences (India)
In this talk, I review recent progress made in two areas of thermal field theory. In par- ticular, I discuss various approaches for the calculation of the quark gluon plasma thermodynamical properties, and the problem of its photon production rate. Keywords. Thermal field theory; quark-gluon plasma. PACS Nos 11.10.Wx; 12.38.
Stochastic cooling of bunched beams from fluctuation and kinetic theory
Energy Technology Data Exchange (ETDEWEB)
Chattopadhyay, S.
1982-09-01
A theoretical formalism for stochastic phase-space cooling of bunched beams in storage rings is developed on the dual basis of classical fluctuation theory and kinetic theory of many-body systems in phase-space. The physics is that of a collection of three-dimensional oscillators coupled via retarded nonconservative interactions determined by an electronic feedback loop. At the heart of the formulation is the existence of several disparate time-scales characterizing the cooling process. Both theoretical approaches describe the cooling process in the form of a Fokker-Planck transport equation in phase-space valid up to second order in the strength and first order in the auto-correlation of the cooling signal. With neglect of the collective correlations induced by the feedback loop, identical expressions are obtained in both cases for the coherent damping and Schottky noise diffusion coefficients. These are expressed in terms of Fourier coefficients in a harmonic decomposition in angle of the generalized nonconservative cooling force written in canonical action-angle variables of the particles in six-dimensional phase-space. Comparison of analytic results to a numerical simulation study with 90 pseudo-particles in a model cooling system is presented.
Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature.
Sørensen, Jesper Givskov; Schou, Mads Fristrup; Kristensen, Torsten Nygaard; Loeschcke, Volker
2016-08-04
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes. Both mean and fluctuation of temperature contributed to thermal acclimation and affected the transcriptome. The transcriptomic response to mean temperatures comprised modification of a major part of the transcriptome, while the response to fluctuations affected a much smaller set of genes, which was highly independent of both the response to a change in mean temperature and to the classic heat shock response. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to contribute to our understanding of thermal adaptation. We provide evidence that environmental sensing, particularly phototransduction, is a central mechanism underlying the regulation of thermal acclimation to fluctuating temperatures. Thus, genes and pathways involved in phototransduction are likely of importance in fluctuating climates.
Squeezing of thermal and quantum fluctuations: Universal features
DEFF Research Database (Denmark)
Svensmark, Henrik; Flensberg, Karsten
1993-01-01
We study the classical and quantum fluctuations of a general damped forced oscillator close to a bifurcation instability. Near the instability point, the fluctuations are strongly phase correlated and are squeezed. In the limit of low damping, it is shown that the system has universal features when...
Proof of the extended Bloch-Messiah theorem in the thermal Hartree-Fock-Bogoliubov theory
Tanabe, K.; Sugawara-Tanabe, K.
1990-09-01
It is shown that an application of the thermo field dynamics (TFD) to the thermal Hartree-Fock-Bogoliubov (THFB) theory leads to the extended form of the Bloch-Messiah theorem for the finite temperature formalism. The generalized density matrix defined on the enlarged operator space including tilded into account the thermal fluctuation of fermion number for the system under consideration.
General Linearized Theory of Quantum Fluctuations around Arbitrary Limit Cycles.
Navarrete-Benlloch, Carlos; Weiss, Talitha; Walter, Stefan; de Valcárcel, Germán J
2017-09-29
The theory of Gaussian quantum fluctuations around classical steady states in nonlinear quantum-optical systems (also known as standard linearization) is a cornerstone for the analysis of such systems. Its simplicity, together with its accuracy far from critical points or situations where the nonlinearity reaches the strong coupling regime, has turned it into a widespread technique, being the first method of choice in most works on the subject. However, such a technique finds strong practical and conceptual complications when one tries to apply it to situations in which the classical long-time solution is time dependent, a most prominent example being spontaneous limit-cycle formation. Here, we introduce a linearization scheme adapted to such situations, using the driven Van der Pol oscillator as a test bed for the method, which allows us to compare it with full numerical simulations. On a conceptual level, the scheme relies on the connection between the emergence of limit cycles and the spontaneous breaking of the symmetry under temporal translations. On the practical side, the method keeps the simplicity and linear scaling with the size of the problem (number of modes) characteristic of standard linearization, making it applicable to large (many-body) systems.
General Linearized Theory of Quantum Fluctuations around Arbitrary Limit Cycles
Navarrete-Benlloch, Carlos; Weiss, Talitha; Walter, Stefan; de Valcárcel, Germán J.
2017-09-01
The theory of Gaussian quantum fluctuations around classical steady states in nonlinear quantum-optical systems (also known as standard linearization) is a cornerstone for the analysis of such systems. Its simplicity, together with its accuracy far from critical points or situations where the nonlinearity reaches the strong coupling regime, has turned it into a widespread technique, being the first method of choice in most works on the subject. However, such a technique finds strong practical and conceptual complications when one tries to apply it to situations in which the classical long-time solution is time dependent, a most prominent example being spontaneous limit-cycle formation. Here, we introduce a linearization scheme adapted to such situations, using the driven Van der Pol oscillator as a test bed for the method, which allows us to compare it with full numerical simulations. On a conceptual level, the scheme relies on the connection between the emergence of limit cycles and the spontaneous breaking of the symmetry under temporal translations. On the practical side, the method keeps the simplicity and linear scaling with the size of the problem (number of modes) characteristic of standard linearization, making it applicable to large (many-body) systems.
Thermal ignition revisited with molecular dynamics: role of fluctuations in activated collisions
Sirmas, Nick
2016-01-01
The problem of thermal ignition in a homogeneous gas is revisited from a molecular dynamics perspective. The simple model assumes reactive particles of type A and B in a fixed domain that react to form type C products if an activation threshold for impact is surpassed. Such a reaction liberates kinetic energy to the product particles, representative of the heat release. The results are compared with those obtained from the continuum description with the reaction rate evaluated from kinetic theory assuming local thermodynamic equilibrium and Maxwell-Boltzmann statistics, in order to assess the role played by molecular fluctuations. Results show that at low activation energies, the ignition time obtained from the molecular dynamics is independent of domain size, with values exceeding what is expected from the continuum model for all values of heat release. The ignition time was found dependent on domain size for larger activation energies. Small domains of $N=100$ particles yielded longer ignition delays than p...
Observation of thermal fluctuations in a superfluid optomechanical system
Kashkanova, A. D.; Shkarin, A. B.; Brown, C. D.; Flowers-Jacobs, N. E.; Childress, L.; Hoch, S. W.; Hohmann, L.; Ott, K.; Garcia, S.; Reichel, J.; Harris, J. G. E.
2017-02-01
In cavity optomechanics the state of a mechanical element can be manipulated by interfacing it with light via radiation pressure, electrostriction, or related phenomena. The majority of mechanical elements employed in optomechanical systems to date are solid objects (membranes, nanowires, mirrors, etc); however fluids can also be used as a mechanical element. Compared to solids, fluids have an advantage: they readily achieve precise alignment with the optical cavity, as the fluid can conformally fill or coat the optical cavity. However, almost all optomechanical systems need to be cooled to sub-Kelvin temperatures in order for quantum effects to be observed. Liquid helium is the only fluid that doesn't solidify under its own pressure at these temperatures. Additionally, helium has almost no optical absorption, high thermal conductivity and very low acoustic loss at cryogenic temperatures. We have developed an optomechanical system in which the mechanical mode is a standing density wave in superfluid helium inside a 70 μm long Fabry-Perot cavity. The optical mode is also a mode of the same cavity. Thus, the system is completely self-aligned. In this system, we used electrostriction to drive the mechanical mode with light by modulating the optical intensity. We also observed the mode's undriven Brownian motion and from that extracted it mean phonon number. We measured phonon number as low as nac=11. The optomechanical effects of optical spring and optical damping were observed, and agreed well with the predictions of conventional optomechanical theory.
Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature
Jesper Givskov Sørensen; Mads Fristrup Schou; Torsten Nygaard Kristensen; Volker Loeschcke
2016-01-01
Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by ...
Fluctuation of a Piston in Vacuum Induced by Thermal Radiation Pressure
Inui, Norio
2017-10-01
We consider the displacement of a piston dividing a vacuum cavity at a finite temperature T induced by fluctuations in the thermal radiation pressure. The correlation function of the thermal radiation pressure is calculated using the theoretical framework developed by Barton, which was first applied to the fluctuation of the Casimir force at absolute zero. We show that the variance of the radiation pressure at a fixed point is proportional to T8 and evaluate the mean square displacement for a piston with a small cross section in a characteristic correlation timescale ħ/(kBT). At room temperature, the contribution of the thermal radiation to the fluctuation is larger than that of the vacuum fluctuation.
Time-Dependent Thermal Transport Theory.
Biele, Robert; D'Agosta, Roberto; Rubio, Angel
2015-07-31
Understanding thermal transport in nanoscale systems presents important challenges to both theory and experiment. In particular, the concept of local temperature at the nanoscale appears difficult to justify. Here, we propose a theoretical approach where we replace the temperature gradient with controllable external blackbody radiations. The theory recovers known physical results, for example, the linear relation between the thermal current and the temperature difference of two blackbodies. Furthermore, our theory is not limited to the linear regime and goes beyond accounting for nonlinear effects and transient phenomena. Since the present theory is general and can be adapted to describe both electron and phonon dynamics, it provides a first step toward a unified formalism for investigating thermal and electronic transport.
Retrieval of Green's functions of elastic waves from thermal fluctuations of fluid-solid systems.
Godin, Oleg A
2009-04-01
Fluctuation-dissipation and flow reversal theorems are used to study long-range correlation of thermal phonons in a stationary heterogeneous mechanical system comprised of arbitrary inhomogeneous fluid flow and anisotropic solid. At thermal equilibrium, with an appropriate choice of physical observables to characterize thermal fluctuations within the fluid and within the solid, the general integral expression for the two-point correlation function of the fluctuations reduces to a linear combination of deterministic Green's functions, which describe wave propagation in opposite directions between the two points. It is demonstrated that the cross-correlation of thermal noise contains as much information about the environment as can be obtained in active reciprocal transmission experiments with transceivers placed at the two points. These findings suggest a possible application of ambient noise cross-correlation to passive acoustic characterization of inhomogeneous flows in fluid-solid systems in laboratory and geophysical settings.
Fluctuation theory of solutions applications in chemistry, chemical engineering, and biophysics
Smith, Paul E
2013-01-01
There are essentially two theories of solutions that can be considered exact: the McMillan-Mayer theory and Fluctuation Solution Theory (FST). The first is mostly limited to solutes at low concentrations, while FST has no such issue. It is an exact theory that can be applied to any stable solution regardless of the number of components and their concentrations, and the types of molecules and their sizes. Fluctuation Theory of Solutions: Applications in Chemistry, Chemical Engineering, and Biophysics outlines the general concepts and theoretical basis of FST and provides a range of applications
Extra phase noise from thermal fluctuations in nonlinear optical crystals
DEFF Research Database (Denmark)
César, J. E. S.; Coelho, A.S.; Cassemiro, K.N.
2009-01-01
We show theoretically and experimentally that scattered light by thermal phonons inside a second-order nonlinear crystal is the source of additional phase noise observed in optical parametric oscillators. This additional phase noise reduces the quantum correlations and has hitherto hindered the d...
Liu, L. P.; Sharma, P.
2013-03-01
Thermal fluctuations renormalize the bending elasticity of lipid bilayers. This well-studied effect is a cornerstone in the study of several membrane biophysical phenomena. Analogously, nearly all membranes are endowed with an electromechanical coupling called flexoelectricity that admits membrane polarization due to curvature changes. Flexoelectricity is found to be important in a number of biological functions, including hearing, ion transport, and in some situations where mechanotransduction is necessary. Very little is known about the interplay between thermal fluctuations and flexoelectricity. In this work, we explore how the apparent flexoelectricity is altered due to thermal fluctuations and, further, how the elastic and dielectric properties are renormalized due to flexoelectricity. We find that the apparent bending rigidity is softened by flexoelectricity and discuss the ramifications for interpreting existing experimental work.
Thermodynamics of higher dimensional black holes with higher order thermal fluctuations
Pourhassan, B.; Kokabi, K.; Rangyan, S.
2017-12-01
In this paper, we consider higher order corrections of the entropy, which coming from thermal fluctuations, and find their effect on the thermodynamics of higher dimensional charged black holes. Leading order thermal fluctuation is logarithmic term in the entropy while higher order correction is proportional to the inverse of original entropy. We calculate some thermodynamics quantities and obtain the effect of logarithmic and higher order corrections of entropy on them. Validity of the first law of thermodynamics investigated and Van der Waals equation of state of dual picture studied. We find that five-dimensional black hole behaves as Van der Waals, but higher dimensional case have not such behavior. We find that thermal fluctuations are important in stability of black hole hence affect unstable/stable black hole phase transition.
Dai, Xiaojiao; Jiang, Yanyi; Hang, Chao; Bi, Zhiyi; Ma, Longsheng
2015-02-23
The temperature stability of optical reference cavities is significant in state-of-the-art ultra-stable narrow-linewidth laser systems. In this paper, the thermal time constant and thermal sensitivity of reference cavities are analyzed when reference cavities respond to environmental perturbations via heat transfer of thermal conduction and thermal radiation separately. The analysis as well as simulation results indicate that a reference cavity enclosed in multiple layers of thermal shields with larger mass, higher thermal capacity and lower emissivity is found to have a larger thermal time constant and thus a smaller sensitivity to environmental temperature perturbations. The design of thermal shields for reference cavities may vary according to experimentally achievable temperature stability and the coefficient of thermal expansion of reference cavities. A temperature fluctuation-induced length instability of reference cavities as low as 6 × 10(-16) on a day timescale can be achieved if a two-layer thermal shield is inserted between a cavity with the coefficient of thermal expansion of 1 × 10(-10) /K and an outer vacuum chamber with temperature fluctuation amplitude of 1 mK and period of 24 hours.
Beyond Gaussian approximation in the spin-fluctuation theory of metallic ferromagnetism
Energy Technology Data Exchange (ETDEWEB)
Reser, B I; Grebennikov, V I [Institute of Metal Physics, Russian Academy of Sciences, Ekaterinburg (Russian Federation); Melnikov, N B, E-mail: reser@imp.uran.r [Lomonosov Moscow State University, Moscow (Russian Federation)
2010-01-15
A characteristic feature of the Gaussian spin-fluctuation theory is the jump transition into the paramagnetic state. We eliminate the jump and obtain a continuous second-order phase transition by taking into account the high-order terms of the free energy of electrons in the fluctuating exchange field. The third-order term of the free energy yields a renormalization of the mean field, and fourth-order term, responsible for the interaction of the fluctuations, gives a renormalization of the spin susceptibility. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar.
Theory of overdispersion in counting statistics caused by fluctuating probabilities
Energy Technology Data Exchange (ETDEWEB)
Semkow, Thomas M. E-mail: semkow@wadsworth.org
1999-11-01
It is shown that the random Lexis fluctuations of probabilities such as probability of decay or detection cause the counting statistics to be overdispersed with respect to the classical binomial, Poisson, or Gaussian distributions. The generating and the distribution functions for the overdispersed counting statistics are derived. Applications to radioactive decay with detection and more complex experiments are given, as well as distinguishing between the source and background, in the presence of overdispersion. Monte-Carlo verifications are provided.
Theory of overdispersion in counting statistics caused by fluctuating probabilities
Semkow, T M
1999-01-01
It is shown that the random Lexis fluctuations of probabilities such as probability of decay or detection cause the counting statistics to be overdispersed with respect to the classical binomial, Poisson, or Gaussian distributions. The generating and the distribution functions for the overdispersed counting statistics are derived. Applications to radioactive decay with detection and more complex experiments are given, as well as distinguishing between the source and background, in the presence of overdispersion. Monte-Carlo verifications are provided.
Two problems in thermal field theory
Indian Academy of Sciences (India)
Abstract. In this talk, I review recent progress made in two areas of thermal ﬁeld theory. In particular, I discuss various approaches for the calculation of the quark gluon plasma thermodynamical properties, and the problem of its photon production rate.
Acoustic Fluctuations Due to Shallow Water Thermal Microstructure
1974-09-01
of horizontal sheets which could cause multiple reflection layers. Very sharp, multiple thermal layers have been reported In the Arctic [Denner 1971...University of Michigan 1970. 7. Denner, W.W., "The Layered Microstructure and Acoustic Propagation in the Arctic Ocean," U.S. Navy Journal of...Inhomogeneities," (in Russian), Radloflz., v. 10, p. 1, 1967. 36. Tatarski, V.l., Wave Propagation in a Turbulent Medium, Translated by R.A. Silverman , McGraw
State-space Geometry, Statistical Fluctuations and Black Holes in String Theory
Bellucci, Stefano
2011-01-01
We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a new perspective of black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic state-space geometric meaning of the statistical fluctuations, local and global stability conditions and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, \\textit{viz.}, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory. Keywords: Intrinsic Geometry; ...
State-Space Geometry, Statistical Fluctuations, and Black Holes in String Theory
Directory of Open Access Journals (Sweden)
Stefano Bellucci
2014-01-01
Full Text Available We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a state-space perspective to the black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic geometric meaning of the statistical fluctuations, local and global stability conditions, and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, namely, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions, and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory.
Kulasiri, Don
2011-01-01
We discuss the quantification of molecular fluctuations in the biochemical reaction systems within the context of intracellular processes associated with gene expression. We take the molecular reactions pertaining to circadian rhythms to develop models of molecular fluctuations in this chapter. There are a significant number of studies on stochastic fluctuations in intracellular genetic regulatory networks based on single cell-level experiments. In order to understand the fluctuations associated with the gene expression in circadian rhythm networks, it is important to model the interactions of transcriptional factors with the E-boxes in the promoter regions of some of the genes. The pertinent aspects of a near-equilibrium theory that would integrate the thermodynamical and particle dynamic characteristics of intracellular molecular fluctuations would be discussed, and the theory is extended by using the theory of stochastic differential equations. We then model the fluctuations associated with the promoter regions using general mathematical settings. We implemented ubiquitous Gillespie's algorithms, which are used to simulate stochasticity in biochemical networks, for each of the motifs. Both the theory and the Gillespie's algorithms gave the same results in terms of the time evolution of means and variances of molecular numbers. As biochemical reactions occur far away from equilibrium-hence the use of the Gillespie algorithm-these results suggest that the near-equilibrium theory should be a good approximation for some of the biochemical reactions. © 2011 Elsevier Inc. All rights reserved.
Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory
Energy Technology Data Exchange (ETDEWEB)
Schlickeiser, R., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yoon, P. H., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)
2015-07-15
Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.
Fluctuational electrodynamics for nonlinear materials in and out of thermal equilibrium
Soo, Heino; Krüger, Matthias
2018-01-01
We develop fluctuational electrodynamics for media with nonlinear optical response in and out of thermal equilibrium. Starting from the stochastic nonlinear Helmholtz equation and using the fluctuation dissipation theorem, we obtain perturbatively a deterministic nonlinear Helmholtz equation for the average field, the physical linear response, as well as the fluctuations and Rytov currents. We show that the effects of nonlinear optics, in or out of thermal equilibrium, can be taken into account with an effective dielectric function. We discuss the heat radiation of a planar, nonlinear surface, showing that Kirchhoff's law must be applied carefully. We find that the spectral emissivity of a nonlinear nanosphere can in principle be negative, implying the possibility of heat-flow reversal for specific frequencies.
London penetration depth and thermal fluctuations in the sulphur hydride 203 K superconductor
Energy Technology Data Exchange (ETDEWEB)
Talantsev, E.F.; Crump, W.P. [Robinson Research Institute, Victoria University of Wellington, Lower Hutt (New Zealand); Storey, J.G.; Tallon, J.L. [Robinson Research Institute, Victoria University of Wellington, Lower Hutt (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology, Lower Hutt (New Zealand)
2017-03-15
Recently, compressed H{sub 2}S has been shown to become superconducting at 203 K under a pressure of 155 GPa. One might expect fluctuations to dominate at such temperatures. Using the magnetisation critical current, we determine the ground-state London penetration depth, λ{sub 0} = 189 nm, and the superconducting energy gap, Δ{sub 0} = 27.8 meV, and find these parameters are similar to those of cuprate superconductors. We also determine the fluctuation temperature scale, T{sub fluc} = 1470 K, which shows that, unlike the cuprates, T{sub c} of the hydride is not limited by fluctuations. This is due to its three dimensionality and suggests the search for better superconductors should refocus on three-dimensional systems where the inevitable thermal fluctuations are less likely to reduce the observed T{sub c}. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Energy Technology Data Exchange (ETDEWEB)
Benhassine, B. [Nantes Univ., 44 (France)
1994-01-14
At intermediate energies the heavy ion collisions can be studied within the framework of a semi-classical approach based on the Vlasov-Uehling-Uhlenbeck (VUU) equation. Such an approach reduces the N-body problem to its description in terms of the one-body distribution function and constitutes the basis of several successful simulation models. Our aim in this work is to extend these average approaches to treat fluctuations. Within the framework of a linear approximation, we derived a Fokker-Planck transport equation in the one-body phase space. When it is reduced to its first moments, one recovers the VUU equation for the average dynamics together with the time evolution equation for the correlations. The collective transport coefficients are then obtained by projection on the one-body collective space. Independently, using a projection method introduced by Van Kampen, based on the constants of motion, we deduce the stationary expressions for the covariance matrix in phase space. We extract then, the equilibrium dispersions of one-body observables in a homogeneous case and in a spherical symmetric one. These results are compared with two types of simulation models in a relaxation time approximation. In the first one which is of Lagrangian type, the collective transport coefficients are directly extracted from the simulation and consequently the numerical fluctuations are washed out. The second model, due to its Eulerian character, allows us to make a microscopical comparison. (author) 58 refs.
Thermal equilibrium of a Brownian particle in a fluctuating fluid: a numerical study
Liu, Yi; Nie, Deming
2017-07-01
In this work the fluctuating lattice Boltzmann method was adopted to simulate the motion of a Brownian particle in a fluid in two dimensions. The temperatures characterizing the translation motion and rotational motion of the particle were calculated to evaluate the thermal equilibrium between the particle and the fluid. Furthermore, the effects of the fluid temperature and viscosity on the fluid pressure fluctuation were investigated. The linear relationships were observed in a log-log coordinate. Besides, the slopes of the linear relation were obtained, which keeps constant for all cases studied.
Urbach's rule derived from thermal fluctuations in the band-gap energy
DEFF Research Database (Denmark)
Skettrup, Torben
1978-01-01
and holes interacting with the phonons. Since the phonon number is fluctuating in thermal equilibrium, the band-gap energy is also fluctuating resulting in an exponential absorption tail below the average band-gap energy. These simple considerations are applied to derive Urbach's rule at high temperatures......, while a simplified model with independent, noninteracting atoms is proposed to explain the behavior of Urbach's rule in the whole temperature range. The three parameters entering Urbach's rule are expressed in terms of parameters derived from the temperature shift of the band gap and from the exciton...
Modelling thermal fluctuations in non-ideal fluids with the lattice Boltzmann method.
Gross, M; Adhikari, R; Cates, M E; Varnik, F
2011-06-13
Recently, we proposed a theoretical framework to include thermal fluctuations into the Lattice Boltzmann (LB) method for non-ideal fluids. Here, we apply a variant thereof to a certain class of force-based non-ideal fluid LB models. We find that ideal-gas-like noise is an exact result of the fluctuation-dissipation theorem in the hydrodynamic regime. It is shown that satisfactory equilibration of the density and fluid momentum can be obtained in a simulation over a wide range of length scales.
Thermalization in a holographic confining gauge theory
Energy Technology Data Exchange (ETDEWEB)
Ishii, Takaaki [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); Kiritsis, Elias [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece); APC, University Paris Diderot, Sorbonne Paris Cité, UMR 7164 CNRS,10, rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Rosen, Christopher [Crete Center for Theoretical Physics, Department of Physics, University of Crete,71003 Heraklion (Greece)
2015-08-03
Time dependent perturbations of states in the holographic dual of a 3+1 dimensional confining theory are considered. The perturbations are induced by varying the coupling to the theory’s most relevant operator. The dual gravitational theory belongs to a class of Einstein-dilaton theories which exhibit a mass gap at zero temperature and a first order deconfining phase transition at finite temperature. The perturbation is realized in various thermal bulk solutions by specifying time dependent boundary conditions on the scalar, and we solve the fully backreacted Einstein-dilaton equations of motion subject to these boundary conditions. We compute the characteristic time scale of many thermalization processes, noting that in every case we examine, this time scale is determined by the imaginary part of the lowest lying quasi-normal mode of the final state black brane. We quantify the dependence of this final state on parameters of the quench, and construct a dynamical phase diagram. Further support for a universal scaling regime in the abrupt quench limit is provided.
Random-matrix-theory approach to mesoscopic fluctuations of heat current
Schmidt, Martin; Kottos, Tsampikos; Shapiro, Boris
2013-08-01
We consider an ensemble of fully connected networks of N oscillators coupled harmonically with random springs and show, using random-matrix-theory considerations, that both the average phonon heat current and its variance are scale invariant and take universal values in the large N limit. These anomalous mesoscopic fluctuations is the hallmark of strong correlations between normal modes.
Evaluation of diffusion coefficients in multicomponent mixtures by means of the fluctuation theory
DEFF Research Database (Denmark)
Shapiro, Alexander
2003-01-01
We derive general expressions for diffusion coefficients in multicomponent non-ideal gas or liquid mixtures. The derivation is based on the general statistical theory of fluctuations around an equilibrium state. The matrix of diffusion coefficients is expressed in terms of the equilibrium thermod...
Influence of thermal fluctuations on dynamics of charged particles in electromagnetic fields
Sametov, E. A.; Timirkhanov, R. A.; Vaulina, O. S.
2017-12-01
The numerical study of dynamics of the charged particles in the confined cloud located in a constant electromagnetic field is presented. Calculations are performed for ions with various masses in a wide range of system parameters. For the first time, an influence of thermal fluctuations of particles on their motion in an electromagnetic field is considered. Analytical estimations for the analysis of this effect are proposed.
Theory of enhancing thermal imaging through fire
Cha, Jae H.; Abbott, A. Lynn; Krapels, Keith A.; Szu, Harold H.
2014-05-01
Fire can overwhelm the field of view of a thermal imaging sensor with intensive radiation, and when presented to observers can cause important cues in the scene to go unnoticed due to the limited dynamic range of displays and of the human visual system. Here we propose a computational method, called software-defined camera (SDC), to improve the image quality for an un-cooled thermal imager seeing through fire that obscures lower-temperature objects in the background. To that end, we developed a novel theory for the arbitrary manipulation of optical radiation sources, which is based on rigorous application of Boltzmann's molecular thermodynamics. On this framework it is possible to formulate the problem of identification and selective removal/suppression of the optical radiation sources, and thus to design a blind source separation algorithm. Application of the developed theory should make it possible to design a low-cost specialty SDC that is able to see through high temperature fire for locating a relatively low temperature objects such as a human body.
Energy Technology Data Exchange (ETDEWEB)
John A. Krommes
2007-10-09
The present state of the theory of fluctuations in gyrokinetic GK plasmas and especially its application to sampling noise in GK particle-in-cell PIC simulations is reviewed. Topics addressed include the Δf method, the fluctuation-dissipation theorem for both classical and GK many-body plasmas, the Klimontovich formalism, sampling noise in PIC simulations, statistical closure for partial differential equations, the theoretical foundations of spectral balance in the presence of arbitrary noise sources, and the derivation of Kadomtsev-type equations from the general formalism.
Ahmadpoor, Fatemeh; Wang, Peng; Huang, Rui; Sharma, Pradeep
2017-10-01
The study of statistical mechanics of thermal fluctuations of graphene-the prototypical two-dimensional material-is rendered rather complicated due to the necessity of accounting for geometric deformation nonlinearity. Unlike fluid membranes such as lipid bilayers, coupling of stretching and flexural modes in solid membranes like graphene leads to a highly anharmonic elastic Hamiltonian. Existing treatments draw heavily on analogies in the high-energy physics literature and are hard to extend or modify in the typical contexts that permeate materials, mechanics and some of the condensed matter physics literature. In this study, using a variational perturbation method, we present a ;mechanics-oriented; treatment of the thermal fluctuations of elastic sheets such as graphene and evaluate their effect on the effective bending stiffness at finite temperatures. In particular, we explore the size, pre-strain and temperature dependency of the out-of-plane fluctuations, and demonstrate how an elastic sheet becomes effectively stiffer at larger sizes. Our derivations provide a transparent approach that can be extended to include multi-field couplings and anisotropy for other 2D materials. To reconcile our analytical results with atomistic considerations, we also perform molecular dynamics simulations on graphene and contrast the obtained results and physical insights with those in the literature.
Primitive interactions between inclusions on a fluid membrane: the role of thermal fluctuations.
Benhamou, M
2011-08-01
Consider a fluid membrane decorated by moving hard or soft inclusions. The aim of this work is a quantitative study of the influence of thermal fluctuations on the three-dimensional primitive forces between these inclusions. Integrating over all membrane fluctuations, we obtain a general form giving the modified primitive interactions upon the transverse distance. The established formalism enables us to obtain the modified expression of some standard interaction potentials. In particular, for power-like potentials, we found a modified expression featuring the Whittaker function. The present formalism may be extended to other primitive interaction potentials. Finally, the main conclusion is that, decorated fluid membranes may be regarded as effective two-dimensional colloidal solutions where inclusions interact via the computed effective interactions.
DEFF Research Database (Denmark)
Ciliberto, S.; Imparato, A.; Naert, A.
2013-01-01
We study both experimentally and theoretically the statistical properties of the energy exchanged between two electrical conductors, kept at different temperatures by two different heat reservoirs, and coupled by the electrical thermal noise. Such a system is ruled by the same equations as two...... Brownian particles kept at different temperatures and coupled by an elastic force. We measure the heat flowing between the two reservoirs and the thermodynamic work done by one part of the system on the other. We show that these quantities exhibit a long-time fluctuation theorem. Furthermore, we evaluate...... the fluctuating entropy, which satisfies a conservation law. These experimental results are fully justified by the theoretical analysis. Our results give more insight into the energy transfer in the famous Feynman ratchet, widely studied theoretically but never in an experiment....
Second-order fluctuation theory and time autocorrelation function for currents.
Belousov, Roman; Cohen, E G D
2016-12-01
By using recent developments for the Langevin dynamics of spatially asymmetric systems, we routinely generalize the Onsager-Machlup fluctuation theory of the second order in time. In this form, it becomes applicable to fluctuating variables, including hydrodynamic currents, in equilibrium as well as nonequilibrium steady states. From the solution of the obtained stochastic equations we derive an analytical expression for the time autocorrelation function of a general fluctuating quantity. This theoretical result is then tested in a study of a shear flow by molecular dynamics simulations. The proposed form of the time autocorrelation function yields an excellent fit to our computational data for both equilibrium and nonequilibrium steady states. Unlike the analogous result of the first-order Onsager-Machlup theory, our expression correctly describes the short-time correlations. Its utility is demonstrated in an application of the Green-Kubo formula for the transport coefficient. Curiously, the normalized time autocorrelation function for the shear flow, which only depends on the deterministic part of the fluctuation dynamics, appears independent of the external shear force in the linear nonequilibrium regime.
Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.
2015-12-01
Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events.
Oka, Hisaki
2016-05-13
Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature.
Jin, Y.-Q.; Kong, J. A.
1985-01-01
The strong fluctuation theory is applied to the study of the atmospheric snowfall which is modeled as a layer of random discrete-scatterers medium. As functions of size distribution, fractional volume, and radius of scatterers, the relationship is illustrated between the reflectivity factor and precipitation rate, the attenuation of the centimeter and millimeter waves, and the line-of-sight transmission of coherent and incoherent wave components. The theoretical results are shown to match favorably with experimental data.
Energy Technology Data Exchange (ETDEWEB)
Nakamura, Y., E-mail: yusuke.n@asagi.waseda.jp [Department of Electronic and Physical Systems, Waseda University, Tokyo 169-8555 (Japan); Nagano Prefectural Kiso Seiho High School, Nagano 397-8571 (Japan); Kawaguchi, T., E-mail: pionelish30@toki.waseda.jp [Department of Electronic and Physical Systems, Waseda University, Tokyo 169-8555 (Japan); Torii, Y., E-mail: torii0139@asagi.waseda.jp [Department of Electronic and Physical Systems, Waseda University, Tokyo 169-8555 (Japan); Yamanaka, Y., E-mail: yamanaka@waseda.jp [Department of Electronic and Physical Systems, Waseda University, Tokyo 169-8555 (Japan)
2017-01-15
The formulation for zero mode of a Bose–Einstein condensate beyond the Bogoliubov approximation at zero temperature [Y. Nakamura et al., Phys. Rev. A 89 (2014) 013613] is extended to finite temperature. Both thermal and quantum fluctuations are considered in a manner consistent with a concept of spontaneous symmetry breakdown for a finite-size system. Therefore, we need a proper treatment of the zero mode operators, which invoke non-trivial enhancements in depletion condensate and thermodynamical quantities such as the specific heat. The enhancements are visible in the weak interaction case. Our approach reproduces the results of a homogeneous system in the Bogoliubov approximation in a large particle number limit.
Analysis of the fluctuations of a laser beam due to thermal turbulence
Ndlovu, Sphumelele; Chetty, Naven
2014-07-01
A laser beam propagating in air and passing through a point diffraction interferometer (PDI) produces stable interferograms that can be used to extract wavefront data such as major atmospheric characteristics: turbulence strength, inner scale and outer scale of the refractive index. These parameters need to be taken into consideration when developing defense laser weapons since they can be affected by thermal fluctuations that are due to the changes in temperature in close proximity to the propagating beam and results in phase shifts that can be used to calculate the temperature which causes wavefront perturbations on a propagating beam.
Large-scale magnetic fields, curvature fluctuations and the thermal history of the Universe
Giovannini, Massimo
2007-01-01
It is shown that gravitating magnetic fields affect the evolution of curvature perturbations in a way that is reminiscent of a pristine non-adiabatic pressure fluctuation. The gauge-invariant evolution of curvature perturbations is used to constrain the magnetic power spectrum. Depending on the essential features of the thermodynamic history of the Universe, the explicit derivation of the bound is modified. The theoretical uncertainty in the constraints on the magnetic energy spectrum is assessed by comparing the results obtained in the case of the conventional thermal history with the estimates stemming from less conventional (but phenomenologically allowed) post-inflationary evolutions.
Instability, rupture and fluctuations in thin liquid films: Theory and computations
Gvalani, Rishabh; Duran-Olivencia, Miguel; Kalliadasis, Serafim; Pavliotis, Grigorios
2017-11-01
Thin liquid films are ubiquitous in natural phenomena and technological applications. They are commonly studied via deterministic hydrodynamic equations, but thermal fluctuations often play a crucial role that still needs to be understood. An example of this is dewetting, which involves the rupture of a thin liquid film and the formation of droplets. Such a process is thermally activated and requires fluctuations to be taken into account self-consistently. Here we present an analytical and numerical study of a stochastic thin-film equation derived from first principles. We scrutinise the behaviour of the stochastic thin film equation in the limit of perfectly correlated noise along the wall-normal direction. We also perform Monte Carlo simulations of the stochastic equation by adopting a numerical scheme based on a spectral collocation method. The numerical scheme allows us to explore the fluctuating dynamics of the thin film and the behaviour of the system's free energy close to rupture. Finally, we also study the effect of the noise intensity on the rupture time, which is in good agreement with previous works. Imperial College London (ICL) President's PhD Scholarship; European Research Council Advanced Grant No. 247031; EPSRC Grants EP/L025159, EP/L020564, EP/P031587, EP/L024926, and EP/L016230/1.
Energy Technology Data Exchange (ETDEWEB)
Utanohara, Yoichi, E-mail: utanohara@inss.co.jp [Institute of Nuclear Safety System, Inc., 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Nakamura, Akira, E-mail: a-naka@inss.co.jp [Institute of Nuclear Safety System, Inc., 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Miyoshi, Koji, E-mail: miyoshi.koji@inss.co.jp [Institute of Nuclear Safety System, Inc., 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205 (Japan); Kasahara, Naoto, E-mail: kasahara@n.t.u-tokyo.ac.jp [University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2016-08-15
Highlights: • A large eddy simulation of a mixing tee was carried out. • Fluid temperature fluctuation could be predicted qualitatively. • Grid convergence was almost attained and the simulation continued until 100 s. • A longer-period temperature fluctuation than the well-known St = 0.2 appeared. • Prediction of long-period temperature fluctuations improves the thermal fatigue assessment. - Abstract: Thermal fatigue cracks may be initiated at mixing tees where high and low temperature fluids flow in and mix. According to a previous study, damage by thermal fatigue depends on the frequency of the fluid temperature fluctuation near the wall surface. Structures have the time constant of structural response that depends on physical properties of the structure and the gain of the frequency response tends to become maximum at the frequency lower than the typical frequency of fluid temperature fluctuation. Hence the effect of the lower frequency, that is, long-period temperature fluctuation is important for the thermal fatigue assessment. The typical frequency of fluid temperature fluctuation is about St = 0.2 (nearly 6 Hz), where St is Strouhal number and means non-dimensional frequency. In the experimental study by Miyoshi et al. (2014), a longer-period fluctuation than St = 0.2 was also observed. Results of a fluid–structure coupled analysis by Kamaya et al. (2011) showed this long-period temperature fluctuation causes severer damage to piping. In the present study, a large eddy simulation was carried out to investigate the predictive performance of the long-period fluid temperature fluctuation more quantitatively. Numerical simulation was conducted for the WATLON experiment which was the water experiment of a mixing tee performed at the Japan Atomic Energy Agency. Four computational grids were used to confirm grid convergence. In the short time (9 s) simulations, tendencies of time-averaged and fluctuated velocities could be followed. Time
Metabolic rate and oxidative stress in insects exposed to low temperature thermal fluctuations.
Lalouette, L; Williams, C M; Hervant, F; Sinclair, B J; Renault, D
2011-02-01
Fluctuating temperatures are a predominant feature of the natural environment but their effects on ectotherm physiology are not well-understood. The warm periods of fluctuating thermal regimes (FTRs) provide opportunities for repair leading to increased survival, but there are also indications of negative effects of warm exposure. In this study, we examined respiration and oxidative stress in adult Alphitobius diaperinus exposed to FTRs and to constant low temperatures. We hypothesized that cold exposure will cause oxidative stress and that FTRs would reduce the amount of chill injuries, via activation of the antioxidant system. We measured V˙CO2, activities of super oxide dismutase (SOD), amounts of total (GSHt) and oxidized glutathione (GSSG) during cold and warm periods of FTRs. Increased severity of cold exposure caused a decrease in the glutathione pool. SOD levels increased during the recovery period in the more severe FTR. The antioxidant response was sufficient to counter the reactive oxygen species production, as the GSH:GSSG ratio increased. We conclude that cold stress causes oxidative damage in these beetles, and that a warm recovery period activates the antioxidant system allowing repair of cold-induced damage, leading to the increased survival previously noted in beetles exposed to fluctuating versus constant temperatures. Copyright © 2010 Elsevier Inc. All rights reserved.
Stomatal control and leaf thermal and hydraulic capacitances under rapid environmental fluctuations.
Directory of Open Access Journals (Sweden)
Stanislaus J Schymanski
Full Text Available Leaves within a canopy may experience rapid and extreme fluctuations in ambient conditions. A shaded leaf, for example, may become exposed to an order of magnitude increase in solar radiation within a few seconds, due to sunflecks or canopy motions. Considering typical time scales for stomatal adjustments, (2 to 60 minutes, the gap between these two time scales raised the question whether leaves rely on their hydraulic and thermal capacitances for passive protection from hydraulic failure or over-heating until stomata have adjusted. We employed a physically based model to systematically study effects of short-term fluctuations in irradiance on leaf temperatures and transpiration rates. Considering typical amplitudes and time scales of such fluctuations, the importance of leaf heat and water capacities for avoiding damaging leaf temperatures and hydraulic failure were investigated. The results suggest that common leaf heat capacities are not sufficient to protect a non-transpiring leaf from over-heating during sunflecks of several minutes duration whereas transpirative cooling provides effective protection. A comparison of the simulated time scales for heat damage in the absence of evaporative cooling with observed stomatal response times suggested that stomata must be already open before arrival of a sunfleck to avoid over-heating to critical leaf temperatures. This is consistent with measured stomatal conductances in shaded leaves and has implications for water use efficiency of deep canopy leaves and vulnerability to heat damage during drought. Our results also suggest that typical leaf water contents could sustain several minutes of evaporative cooling during a sunfleck without increasing the xylem water supply and thus risking embolism. We thus submit that shaded leaves rely on hydraulic capacitance and evaporative cooling to avoid over-heating and hydraulic failure during exposure to typical sunflecks, whereas thermal capacitance provides
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sabyasachi, E-mail: sabyaphy@gmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Sao Paulo, SP (Brazil). Instituto de Fisica Teorica
2015-12-15
Owing to the Kubo relation, the shear viscosities of pionic and nucleonic components have been evaluated from their corresponding retarded correlators of viscous stress tensor in the static limit, which become non-divergent only for the non-zero thermal widths of the constituent particles. In the real-time thermal field theory, the pion and nucleon thermal widths have respectively been obtained from the pion self-energy for different meson, baryon loops, and the nucleon self-energy for different pion-baryon loops. We have found non-monotonic momentum distributions of pion and nucleon thermal widths, which have been integrated out by their respective Bose-enhanced and Pauli-blocked phase space factors during evaluation of their shear viscosities. The viscosity to entropy density ratio for this mixed gas of pion-nucleon system decreases and approaches its lower bound as the temperature and baryon chemical potential increase within the relevant domain of hadronic matter. (author)
Altruistic behavior pays, or the importance of fluctuations in evolutionary game theory
Sánchez, Angel; Cuesta, José A.; Roca, Carlos P.
2005-07-01
Human behavior is one of the main problems for evolution, as it is often the case that human actions are disadvantageous for the self and advantageous for other people. Behind this puzzle are our beliefs about rational behavior, based on game theory. Here we show that by going beyond the standard game-theoretical conventions, apparently altruistic behavior can be understood as self-interested. We discuss in detail an example related to the so called Ultimatum game and illustrate the appearance of altruistic behavior induced by fluctuations. In addition, we claim that in general settings, fluctuations play a very relevant role, and we support this claim by considering a completely different example, namely the Stag-Hunt game.
A phenomenological theory of Eulerian and Lagrangian velocity fluctuations in turbulent flows
Chevillard, Laurent; Arneodo, Alain; Leveque, Emmanuel; Pinton, Jean-Francois; Roux, Stephane
2011-01-01
A phenomenological theory of the fluctuations of velocity occurring in a fully developed homogeneous and isotropic turbulent flow is presented. The focus is made on the fluctuations of the spatial (Eulerian) and temporal (Lagrangian) velocity increments. The universal nature of the intermittency phenomenon as observed in experimental measurements and numerical simulations is shown to be fully taken into account by the multiscale picture proposed by the multifractal formalism, and its extensions to the dissipative scales and to the Lagrangian framework. The article is devoted to the presentation of these arguments and to their comparisons against empirical data. In particular, explicit predictions of the statistics, such as probability density functions and high order moments, of the velocity gradients and acceleration are derived. In the Eulerian framework, at a given Reynolds number, they are shown to depend on a single parameter function called the singularity spectrum and to a universal constant governing ...
Bartelmann, Matthias; Fabis, Felix; Kozlikin, Elena; Lilow, Robert; Dombrowski, Johannes; Mildenberger, Julius
2017-08-01
In earlier work, we have developed a kinetic field theory (KFT) for cosmological structure formation and showed that the nonlinear density-fluctuation power spectrum known from numerical simulations can be reproduced quite well even if particle interactions are taken into account to first order only. Besides approximating gravitational interactions, we had to truncate the initial correlation hierarchy of particle momenta at the second order. Here, we substantially simplify KFT. We show that its central object, the free generating functional, can be factorised, taking the full hierarchy of momentum correlations into account. The factors appearing in the generating functional, which we identify as nonlinearly evolved density-fluctuation power spectra, have a universal form and can thus be tabulated for fast access in perturbation schemes. In this paper, we focus on a complete evaluation of the free generating functional of KFT, not including particle interactions yet. This implies that the nonlinearly evolved power spectra contain a damping term which reflects that structures are being wiped out at late times by free streaming. Once particle interactions will be taken into account, they will compensate this damping. If we suppress this damping in a way suggested by the fluctuation-dissipation relations of KFT, our results show that the complete hierarchy of initial momentum correlations is responsible for a large part of the characteristic nonlinear deformation and the mode transport in the density-fluctuation power spectrum. Without any adjustable parameters, KFT accurately reproduces the scale at which nonlinear evolution sets in. Finally, we further develop perturbation theory based on the factorisation of the generating functional and propose a diagrammatic scheme for the perturbation terms.
Fluctuating shells under pressure
Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.
2012-01-01
Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558
DEFF Research Database (Denmark)
Galliero, Guillaume; Medvedev, Oleg; Shapiro, Alexander
2005-01-01
A 322 (2004) 151). In the current study, a fast molecular dynamics scheme has been developed to determine the values of the penetration lengths in Lennard-Jones binary systems. Results deduced from computations provide a new insight into the concept of penetration lengths. It is shown for four different...... binary liquid mixtures of non-polar components that computed penetration lengths, for various temperatures and compositions, are consistent with those deduced from experiments in the framework of the formalism of the fluctuation theory. Moreover, the mutual diffusion coefficients obtained from a coupled...
Niestemski, Liang R.; Chen, Man; Prevost, Robert; McRae, Michael; Cholleti, Sharath; Najarro, Gabriel; Buchman, Timothy G.; Deem, Michael W.
2013-03-01
Contrary to the traditional view of the healthy physiological state as being a single static state, variation in physiologic variables has more recently been suggested to be a key component of the healthy state. Indeed, aging and disease are characterized by a loss of such variability. We apply the conceptual framework of fluctuation-dissipation theory (FDT) to predict the response to a common clinical intervention from historical fluctuations in physiologic time series data. The non-equilibrium FDT relates the response of a system to a perturbation to natural fluctuations in the stationary state of the system. We seek to understand with the FDT a common clinical perturbation, the spontaneous breathing trial (SBT), in which mechanical ventilation is briefly suspended while the patient breathes freely for a period of time. As a stress upon the heart of the patient, the SBT can be characterized as a perturbation of heart rate dynamics. A non-equilibrium, but steady-state FDT allows us to predict the heart rate recovery after the SBT stress. We show that the responses of groups of similar patients to the spontaneous breathing trial can be predicted by this approach. This mathematical framework may serve as part of the basis for personalized critical care.
Thermal fluctuations in Y-Ba-Cu-O thin films near the transition temperature
Energy Technology Data Exchange (ETDEWEB)
Jiang, S.; Hallemeier, P.; Surya, C. (Northeastern Univ., Boston, MA (United States). Dept. of Electrical and Computer Engineering); Phillips, J.M. (AT and T Bell Labs., Murray Hill, NJ (United States))
1994-11-01
Detailed studies on the properties of low frequency noise in Y-Ba-Cu-O thin films in the transition region were conducted. The experimental results showed that the low frequency excess noise exhibited a lower cutoff frequency of about 5 Hz, below which the noise power spectra were independent of frequency. At T close to [Tc] and at small current biases the voltage noise power spectra were proportional to I[sup 2], ([partial derivative]R/[partial derivative]T)[sup 2] and inversely proportional to the volume of the device, [Omega]. In addition, low frequency noise measured from two segments separated by a distance of 300 [mu]m was found to be correlated. The lower cutoff frequencies computed for both the noise power spectra and the frequency dependent correlation function, according to the thermal fluctuation model, were found to be in good agreement with the experimental values. The experimental results provide strong evidence that the low frequency excess noise in the device originates from equilibrium temperature fluctuations for small I and T [approx equal] [Tc].
DEFF Research Database (Denmark)
Antonov, A. A.; Pankratov, A. L.; Yulin, A. V.
2000-01-01
The nonlinear dynamics of fluxons in Josephson systems with dispersion and thermal fluctuations is analyzed using the "quasiparticle" approach to investigate the influence of noise on the Cherenkov radiation effect. Analytical expressions for the stationary amplitude of the emitted radiation...... and its spectral distribution have been obtained in an annular geometry. It is demonstrated that noise reduces the amplitude of the radiated wave and broadens its spectrum. The effect of the radiated wave on the fluxon dynamics leads to a considerably smaller linewidth than observed in the usual flux flow...... oscillator. A resonant behavior of both the mean amplitude and the linewidth as functions of bias current is found. The obtained results enable an optimization of the main parameters (power, tunability, and linewidth) of practical mm- and sub-mm wave Cherenkov flux flow oscillators....
Probing non-thermal density fluctuations in the one-dimensional Bose gas
Directory of Open Access Journals (Sweden)
Jacopo De Nardis, Miłosz Panfil, Andrea Gambassi, Leticia F. Cugliandolo, Robert Konik, Laura Foini
2017-09-01
Full Text Available Quantum integrable models display a rich variety of non-thermal excited states with unusual properties. The most common way to probe them is by performing a quantum quench, i.e., by letting a many-body initial state unitarily evolve with an integrable Hamiltonian. At late times, these systems are locally described by a generalized Gibbs ensemble with as many effective temperatures as their local conserved quantities. The experimental measurement of this macroscopic number of temperatures remains elusive. Here we show that they can be obtained by probing the dynamical structure factor of the system after the quench and by employing a generalized fluctuation-dissipation theorem that we provide. Our procedure allows us to completely reconstruct the stationary state of a quantum integrable system from state-of-the-art experimental observations.
The effect of thermal fluctuations on Holstein polaron dynamics in electric field
Voulgarakis, Nikolaos K.
2017-08-01
In this work, we have studied the effects of thermal fluctuations on the stability of polaron motion under the influence of an external electric field. Zero temperature calculations have been reported previously showing the existence of critical electric field, Ecr, where the system transitions from a stable polaron motion to a Bloch-like oscillation. In this study, we further report that for intermediate polaron sizes the lifetime of such Bloch-like oscillations decay with time due to excessive phonon emission. Our numerical simulations show that the value of Ecr is finite for small temperatures. However, Ecr rapidly decreases with increasing T and becomes practically zero for T > Tcr. In this small but finite temperature window, we report how temperature affects (a) the electric current density, and (b) the Bloch-like frequencies.
Temporal dynamics in an immunological synapse: Role of thermal fluctuations in signaling
Bush, Daniel R.; Chattopadhyay, Amit K.
2015-07-01
The article analyzes the contribution of stochastic thermal fluctuations in the attachment times of the immature T-cell receptor TCR: peptide-major-histocompatibility-complex pMHC immunological synapse bond. The key question addressed here is the following: how does a synapse bond remain stabilized in the presence of high-frequency thermal noise that potentially equates to a strong detaching force? Focusing on the average time persistence of an immature synapse, we show that the high-frequency nodes accompanying large fluctuations are counterbalanced by low-frequency nodes that evolve over longer time periods, eventually leading to signaling of the immunological synapse bond primarily decided by nodes of the latter type. Our analysis shows that such a counterintuitive behavior could be easily explained from the fact that the survival probability distribution is governed by two distinct phases, corresponding to two separate time exponents, for the two different time regimes. The relatively shorter timescales correspond to the cohesion:adhesion induced immature bond formation whereas the larger time reciprocates the association:dissociation regime leading to TCR:pMHC signaling. From an estimate of the bond survival probability, we show that, at shorter timescales, this probability PΔ(τ ) scales with time τ as a universal function of a rescaled noise amplitude D/Δ2, such that PΔ(τ ) ˜τ-(Δ/√{D }+1/2 ) ,Δ being the distance from the mean intermembrane (T cell:Antigen Presenting Cell) separation distance. The crossover from this shorter to a longer time regime leads to a universality in the dynamics, at which point the survival probability shows a different power-law scaling compared to the one at shorter timescales. In biological terms, such a crossover indicates that the TCR:pMHC bond has a survival probability with a slower decay rate than the longer LFA-1:ICAM-1 bond justifying its stability.
Pressure dependence of critical temperature of bulk FeSe from spin fluctuation theory
Hirschfeld, Peter; Kreisel, Andreas; Wang, Yan; Tomic, Milan; Jeschke, Harald; Jacko, Anthony; Valenti, Roser; Maier, Thomas; Scalapino, Douglas
2013-03-01
The critical temperature of the 8K superconductor FeSe is extremely sensitive to pressure, rising to a maximum of 40K at about 10GPa. We test the ability of the current generation of fluctuation exchange pairing theories to account for this effect, by downfolding the density functional theory electronic structure for each pressure to a tight binding model. The Fermi surface found in such a procedure is then used with fixed Hubbard parameters to determine the pairing strength using the random phase approximation for the spin singlet pairing vertex. We find that the evolution of the Fermi surface captured by such an approach is alone not sufficient to explain the observed pressure dependence, and discuss alternative approaches. PJH, YW, AK were supported by DOE DE-FG02-05ER46236, the financial support of MT, HJ, and RV from the DFG Schwerpunktprogramm 1458 is kindly acknowledged.
Structures of alkyl benzoate binary mixtures. A Kirkwood-Buff fluctuation theory study using UNIFAC.
Alcalde, Rafael; Aparicio, Santiago; García, Begoña; Leal, José M
2005-10-27
The structure of the alkyl benzoate + n-alkane, and + alkan-1-ol binary mixtures were analyzed according to the Kirkwood-Buff fluctuation theory on the basis of both the mixture properties measured over a wide temperature range and the activity coefficients calculated with the modified UNIFAC (Dortmund) model as well. Application of this model reveals that both the microheterogeneous structure and the clustering effects are strongly dependent on the chain length of the n-alkane and alkan-1-ol cosolvents. Knowledge of the local composition around each type of molecule is drawn from the Kirkwood-Buff integrals and the excess (or deficit) molecules aggregated around a central one. The rather high values of the integrals evaluated for some of these systems provide first-hand evidence for phase splitting. The conclusions drawn support previous analyses and confirm the adequacy of the methodology put forward for studying liquid mixtures at microscopic level; easily measurable experimental properties can advantageously be used with the fluctuation theory.
Walewski, Łukasz; Forbert, Harald; Marx, Dominik
2013-03-18
The combined effect of thermal fluctuations and quantum mechanical motion on the HCl(H2O)4 cluster is studied at different temperatures. Two conformations of this cluster are investigated: the ringlike structure that involves an undissociated HCl molecule (UD) and the contact ion pair (CIP), which involves the dissociated acid, Cl(-), and H3O(+). The UD structure is affected by thermal and quantum fluctuations in a similar way. The hydrogen-bond network is destabilized, and this results in ring expansion and proton orientational rearrangements, though the thermal excitation prevails over the quantum effects at high temperature, while the zero-point motion dominates in the low-temperature regime, as expected. In contrast, the thermal and quantum fluctuations exert competing effects on the CIP structure. At high temperature one of the hydrogen bonds accepted by Cl(-) breaks, and this results in undercoordination of the Cl site, which leads to proton transfer along the fluxional Cl(-)···H3O(+) hydrogen bond and formation of molecular HCl. Thus, thermal fluctuations counteract acid dissociation and thus ion-pair formation. At low temperature however, the decreasing thermal excitations facilitate recovery of the full hydrogen-bond network, which pushes the proton away from the Cl site and thus leads to acid dissociation, which characterizes the equilibrium structure. On the other hand, quantum mechanical fluctuations, which destabilize the hydrogen bonds supporting the Cl(-) ion and pull the proton back towards the undissociated limit, become of overriding importance in the low-temperature limit. As a result, the subtle balance between the two trends enables temperature-dependent "low-barrier hydrogen bonding" and establishes a centered hydrogen bond, H2O···H(+)···Cl(-), at intermediate temperatures. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Galitski, Victor; Takei, So; Condensed Matter Theory Center; Joint Quantum Institute Team
2013-03-01
Motivated by the recent experiment of Wang et al. [Nat. Phys. 6, 389 (2010)], who observed a highly unusual transport behavior of ferromagnetic cobalt nanowires proximity-coupled to superconducting electrodes, we study the proximity effect and temperature-dependent transport in such a mesoscopic hybrid structure. It is assumed that the asymmetry in the tunneling barrier gives rise to the Rashba spin-orbit coupling in the barrier that enables induced p-wave superconductivity in the ferromagnet to exist. We first develop a microscopic theory of Andreev scattering at the spin-orbit-coupled interface, derive a set of self-consistent boundary conditions, and find an expression for the p-wave minigap in terms of the microscopic parameters of the contact. Second, we study the temperature dependence of the resistance near the superconducting transition, and we find that it should generally feature a fluctuation-induced peak. The upturn in resistance is related to the suppression of the single-particle density of states due to the formation of fluctuating pairs, whose tunneling is suppressed. In conclusion, we discuss this and related setups involving ferromagnetic nanowires in the context of one-dimensional topological superconductors. Funding support: DOE-BES (DESC0001911).
A phenomenological theory of Eulerian and Lagrangian velocity fluctuations in turbulent flows
Chevillard, Laurent; Castaing, Bernard; Arneodo, Alain; Lévêque, Emmanuel; Pinton, Jean-François; Roux, Stéphane G.
2012-11-01
A phenomenological theory of the fluctuations of velocity occurring in a fully developed homogeneous and isotropic turbulent flow is presented. The focus is made on the fluctuations of the spatial (Eulerian) and temporal (Lagrangian) velocity increments. The universal nature of the intermittency phenomenon as observed in experimental measurements and numerical simulations is shown to be fully taken into account by the multiscale picture proposed by the multifractal formalism, and its extensions to the dissipative scales and to the Lagrangian framework. The article is devoted to the presentation of these arguments and to their comparisons against empirical data. In particular, explicit predictions of the statistics, such as probability density functions and high order moments, of the velocity gradients and acceleration are derived. In the Eulerian framework, at a given Reynolds number, they are shown to depend on a single parameter function called the singularity spectrum and to a universal constant governing the transition between the inertial and dissipative ranges. The Lagrangian singularity spectrum compares well with its Eulerian counterpart by a transformation based on incompressibility, homogeneity and isotropy and the remaining constant is shown to be difficult to estimate on empirical data. It is finally underlined the limitations of the increment to quantify accurately the singular nature of Lagrangian velocity. This is confirmed using higher order increments unbiased by the presence of linear trends, as they are observed on velocity along a trajectory.
Thermal-field emission flicker (1/f) noise and diffusive equilibrium density fluctuations
Gesley, Mark; Swanson, Lyn
1988-06-01
A model of diffusive equilibrium density fluctuations in a grand-canonical ensemble is constructed for systems of finite size. The particle number autocorrelation is developed from a Langevin-type bounded-diffusion equation. Both probe and sample geometries affect its spectrum, which factors into two terms representing the particle creation rate and diffusion according to a multidimensional Carson's theorem. The spatial decay of the kernel in the spectrum's integral equation is measured by a frequency-dependent correlation length that depends on particle lifetime, diffusivity, and probe resolution. The kernel and its transform, the mutual coherence function, collapse to the Ornstein-Zernike spatial distribution but with the new result that the classical correlation length is given by a ratio of diffusive and thermodynamic variables. For the limiting case of an unbounded system with infinite particle lifetime, Voss and Clarke's spatially correlated spectrum is rederived. However, for this ensemble a finite particle lifetime is a necessary equilibrium condition. Little's theorem is generalized when particle interactions are included. Noise-power integrals converge in all cases. Frequency exponents characterize the spectra and, when a small region is probed in a quasi-two-dimensional system, broadband 1/f noise occurs. A Lorentzian spectrum results in the limit of no diffusion. A lower length limit introduced to avoid the breakdown of the diffusion approximation at small time and space intervals can in some cases be identified with probe resolution and is measurable when a certain crossover in frequency exponents is identified. The analysis is then applied to fluctuations in the electron current, thermal field emitted from a single-crystal tungsten cathode. These are coupled to self-diffusion of surface defect adatoms on the cathode by the Fowler-Nordheim equation. Other frequency crossovers yield surface diffusivities and their activation energies, which for
Energy Technology Data Exchange (ETDEWEB)
Braun-Munzinger, P., E-mail: p.braun-munzinger@gsi.de [Extreme Matter Institute EMMI, GSI, Darmstadt (Germany); Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany); Rustamov, A., E-mail: a.rustamov@cern.ch [Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany); National Nuclear Research Center, Baku (Azerbaijan); Stachel, J., E-mail: stachel@physi.uni-heidelberg.de [Physikalisches Institut, Universität Heidelberg, Heidelberg (Germany)
2017-04-15
We develop methods to deal with non-dynamical contributions to event-by-event fluctuation measurements of net-particle numbers in relativistic nuclear collisions. These contributions arise from impact parameter fluctuations and from the requirement of overall net-baryon number or net-charge conservation and may mask the dynamical fluctuations of interest, such as those due to critical endpoints in the QCD phase diagram. Within a model of independent particle sources we derive formulae for net-particle fluctuations and develop a rigorous approach to take into account contributions from participant fluctuations in realistic experimental environments and at any cumulant order. Interestingly, contributions from participant fluctuations to the second and third cumulants of net-baryon distributions are found to vanish at mid-rapidity for LHC energies while higher cumulants of even order are non-zero even when the net-baryon number at mid-rapidity is zero. At lower beam energies the effect of participant fluctuations increases and induces spurious higher moments. The necessary corrections become large and need to be carefully taken into account before comparison to theory. We also provide a procedure for selecting the optimal phase–space coverage of particles for fluctuation analyses and discuss quantitatively the necessary correction due to global charge conservation.
Thermal Field Theory in Small Systems
Horowitz, W. A.
2017-09-01
We compute the finite size corrections to the partition function in a Cartesian space of finite extent in M directions and of infinite extent in D - M directions for a massless, non-interacting scalar field theory. We then use this partition function to compute numerically the energy density, pressure, entropy density, and speed of sound for this theory for M = 1, 2, and 3 for D = 3 total spatial dimensions. The finite size corrections for the speed of sound are ˜ 600%, which indicates the need to consider these corrections in hydrodynamic simulations of small collision systems in high energy nuclear physics.
Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani
2017-12-01
The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.
An Extension to the Theory of Fluctuations in an Equilibrium Convective Ensemble
Penland, M. C.; Bao, J.
2012-12-01
The theory of fluctuations in an equilibrium convective ensemble emerging in the literature is revisited and extended in this study. The probability of requiring n mutually independently convective plumes and a total cloud-base mass flux M for subgrid convection to occur in a given grid box is derived based on the concept of the grand canonical ensemble, which is well known in classic statistical mechanics. The probability distribution functions of the cloud-base mass flux and the number of subgrid convective plumes are dependent on the average of each of the two quantities. This problem has been considered in previous work (e.g., Craig and Cohen 2006), where n was distributed as a Poisson process. It turns out that deriving the distribution describing n simultaneously with that describing the cloud-base mass flux yields a geometric distribution rather than a Poisson distribution. In fact, though the two distributions are quite different, they are logically consistent since the geometric distribution can result if the rate parameter of a Poisson distribution is itself random and distributed exponentially. Other, physically based distributions for the rate parameter are possible, and we introduce one based on a stochastic model of vertical velocity. The work here is thus an extension rather than an alternative to the Craig-Cohen theory.
Introduction to the theory of thermal neutron scattering
Squires, G L
2012-01-01
Since the advent of the nuclear reactor, thermal neutron scattering has proved a valuable tool for studying many properties of solids and liquids, and research workers are active in the field at reactor centres and universities throughout the world. This classic text provides the basic quantum theory of thermal neutron scattering and applies the concepts to scattering by crystals, liquids and magnetic systems. Other topics discussed are the relation of the scattering to correlation functions in the scattering system, the dynamical theory of scattering and polarisation analysis. No previous knowledge of the theory of thermal neutron scattering is assumed, but basic knowledge of quantum mechanics and solid state physics is required. The book is intended for experimenters rather than theoreticians, and the discussion is kept as informal as possible. A number of examples, with worked solutions, are included as an aid to the understanding of the text.
A gauge-invariant reorganization of thermal gauge theory
Energy Technology Data Exchange (ETDEWEB)
Su, Nan
2010-07-01
This dissertation is devoted to the study of thermodynamics for quantum gauge theories. The poor convergence of quantum field theory at finite temperature has been the main obstacle in the practical applications of thermal QCD for decades. In this dissertation I apply hard-thermal-loop perturbation theory, which is a gauge-invariant reorganization of the conventional perturbative expansion for quantum gauge theories to the thermodynamics of QED and Yang-Mills theory to three-loop order. For the Abelian case, I present a calculation of the free energy of a hot gas of electrons and photons by expanding in a power series in m{sub D}/T, m{sub f}/T and e{sup 2}, where m{sub D} and m{sub f} are the photon and electron thermal masses, respectively, and e is the coupling constant. I demonstrate that the hard-thermal-loop perturbation reorganization improves the convergence of the successive approximations to the QED free energy at large coupling, e {proportional_to} 2. For the non-Abelian case, I present a calculation of the free energy of a hot gas of gluons by expanding in a power series in m{sub D}/T and g{sup 2}, where m{sub D} is the gluon thermal mass and g is the coupling constant. I show that at three-loop order hard-thermal-loop perturbation theory is compatible with lattice results for the pressure, energy density, and entropy down to temperatures T {proportional_to} 2 - 3 T{sub c}. The results suggest that HTLpt provides a systematic framework that can be used to calculate static and dynamic quantities for temperatures relevant at LHC. (orig.)
Theory of elasticity and thermal stresses explanations, problems and solutions
Eslami, M Reza; Ignaczak, Józef; Noda, Naotake; Sumi, Naobumi; Tanigawa, Yoshinobu
2013-01-01
This book contains the elements of the theory and the problems of Elasticity and Thermal Stresses with full solutions. The emphasis is placed on problems and solutions and the book consists of four parts: one part is on The Mathematical Theory of Elasticity, two parts are on Thermal Stresses and one part is on Numerical Methods. The book is addressed to higher level undergraduate students, graduate students and engineers and it is an indispensable companion to all who study any of the books published earlier by the authors. This book links the three previously published books by the authors into one comprehensive entity.
Directory of Open Access Journals (Sweden)
Bahador Marzban
2017-04-01
Full Text Available Mechanics of the bilayer membrane play an important role in many biological and bioengineering problems such as cell–substrate and cell–nanomaterial interactions. In this work, we study the effect of thermal fluctuation and the substrate elasticity on the cell membrane–substrate adhesion. We model the adhesion of a fluctuating membrane on an elastic substrate as a two-step reaction comprised of the out-of-plane membrane fluctuation and the receptor–ligand binding. The equilibrium closed bond ratio as a function of substrate rigidity was computed by developing a coupled Fourier space Brownian dynamics and Monte Carlo method. The simulation results show that there exists a crossover value of the substrate rigidity at which the closed bond ratio is maximal.
Swicord, Mays Littleton
This work describes the development and implementation of an optical detection method for determining the microwave absorption properties of liquids and liquid suspensions. The method employs a Mach-Zehnder interferometer illuminated with a single-frequency laser to detect fluctuations in the index of refraction of a transparent or semi-transparent substance placed in one arm of the interferometer. The fluctuations are induced by pulses of microwave energy which are introduced into the sample by a specially designed waveguide sample holder. The laser beams from the sample and reference arms of the interferometer recombine on a photodetector resulting in a heterodyne signal. This general method is called Phase Fluctuation Optical Heterodyne (PFLOH) spectroscopy. The method is theoretically capable of detecting refractive index changes of two parts in 10('12) in liquids with greater sensitivity for gases; however, experimental performance is somewhat more limited. Although there is an abundance of microwave spectroscopy literature, virtually all of it is devoted to the absorption properties of gases. There are two reasons for the lack of information on nongaseous substances. First, methods most commonly used on gases, such as absorption ratio methods, are not practical for liquids in this frequency range due to the difficulties of making accurate microwave measurements. PFLOH spectroscopy avoids this difficulty. Second, fine structure (or anomalous dispersion) in the microwave absorption spectra of liquids has been considered nonexistant or at best uninteresting. This level of interest is changing, however, due to possible biological effects of microwave radiation. A number of different types of biological responses have recently been observed and reported in animals exposed to microwave radiation. Some of these effects are clearly responses of the organism to increased local or whole body temperature levels. In some cases the response is not so clearly thermal in
Workshop on Thermal Field Theory to Neural Networks
Veneziano, Gabriele; Aurenche, Patrick
1996-01-01
Tanguy Altherr was a Fellow in the Theory Division at CERN, on leave from LAPP (CNRS) Annecy. At the time of his accidental death in July 1994, he was only 31.A meeting was organized at CERN, covering the various aspects of his scientific interests: thermal field theory and its applications to hot or dense media, neural networks and its applications to high energy data analysis. Speakers were among his closest collaborators and friends.
Nesic, Svetozar; Cuerno Rejado, Rodolfo; Moro Egido, Esteban
2013-11-01
It has been shown that, in the regime controlled by surface tension, the spreading dynamics of a thin viscous fluid droplet changes significantly when it is subjected to thermal fluctuations. Technically, this has been accomplished through the incorporation of appropriate stochastic terms into the standard lubrication equation. In practice, it leads to a modification of the classic Tanner's law for spreading, with implications for Micro and Nanofluidic systems. We have recently found a new law of spreading for the same kind of systems, but in the gravity-dominated regime. Moreover, in the deteministic case a finite contact angle is formed when a van der Waals attractive force is introduced to the system and we show that there is a slight change in contact angle when thermal fluctuations are taken into account. Ph.D student and a member of GISC (http://matematicas.uc3m.es/index.php/gisc).
Czech Academy of Sciences Publication Activity Database
Fořt, J.; Beran, Pavel; Konvalinka, P.; Pavlík, Z.; Černý, R.
2017-01-01
Roč. 57, č. 3 (2017), s. 159-166 ISSN 1210-2709 R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : in-situ monitoring * temperature * relative humidity * thermal insulation * energy sustainability * seasonal fluctuations Subject RIV: JN - Civil Engineering OBOR OECD: Construction engineering, Municipal and structural engineering https://ojs.cvut.cz/ojs/index.php/ap/article/view/4087/4171
Shimozawa, Masaaki; Suzuki, Yoshitaka; Sugii, Kaori; Ueda, Akira; Yamada, Shogo; Imai, Yusuke; Torizuka, Kiyoshi; Uwatoko, Yoshiya; Mori, Hatsumi; Yamashita, Minoru
We report the thermal transport properties of a quantum spin liquid candidate κ-H3(Cat-EDT-TTF)2 (H-CAT) with a two-dimensional nearly isotropic triangular lattice. Above 1.0 K, thermal conductivity of H-CAT is substantially smaller than that of a deuterated non-magnetic sample (D-CAT) despite no spin thermal conductivity in D-CAT. In the zero-temperature limit, a finite T-linear term of the thermal conductivity of H-CAT is clearly observed when the heat current is parallel to c-axis, while it is almost zero when the heat current is parallel to b-axis. These features would be attributed to anisotropic proton fluctuations present in H-CAT.
Wiebler, James M; Kumar, Manisha; Muir, Timothy J
2017-12-01
Although seasonal increases in cold hardiness are well documented for temperate and polar ectotherms, relatively little is known about supplemental increases in cold hardiness during winter. Because many animals are exposed to considerable thermal variation in winter, they may benefit from a quick enhancement of cold tolerance prior to extreme low temperature. Hatchling painted turtles (Chrysemys picta) overwintering in their natal nests experience substantial thermal variation in winter, and recently, it was found that brief subzero chilling of winter-acclimated hatchlings decreases subsequent chilling-induced mortality, increases blood concentrations of glucose and lactate, and protects the brain from cryoinjury. Here, we further characterize that phenomenon, termed 'cold conditioning', by exposing winter-acclimated hatchling turtles to -3.5, -7.0, or -10.5 °C gradually or repeatedly via daily thermal fluctuations over the course of 5 days and assessing their survival of a subsequent cold shock to a discriminating temperature of -12.7 °C. To better understand the physiological response to cold conditioning, we measured changes in glucose and lactate concentrations in the liver, blood, and brain. Cold conditioning significantly increased cold-shock survival, from 9% in reference turtles up to 74% in cold-conditioned turtles, and ecologically relevant daily thermal fluctuations were at least as effective at conferring cryoprotection as was gradual cold conditioning. Cold conditioning increased glucose concentrations, up to 25 μmol g -1 , and lactate concentrations, up to 30 μmol g -1 , in the liver, blood, and brain. Turtles that were cold conditioned with daily thermal fluctuations accumulated more glucose in the liver, blood, and brain, and had lower brain lactate, than those gradually cold conditioned. Given the thermal variation to which hatchling painted turtles are exposed in winter, we suggest that the supplemental protection conferred by cold
Cantorian Fractal Space-Time Fluctuations in Turbulent Fluid Flows and the Kinetic Theory of Gases
Selvam, A. M.
1999-01-01
Fluid flows such as gases or liquids exhibit space-time fluctuations on all scales extending down to molecular scales. Such broadband continuum fluctuations characterise all dynamical systems in nature and are identified as selfsimilar fractals in the newly emerging multidisciplinary science of nonlinear dynamics and chaos. A cell dynamical system model has been developed by the author to quantify the fractal space-time fluctuations of atmospheric flows. The earth's atmosphere consists of a m...
Thermal rectification based on phonon hydrodynamics and thermomass theory
Directory of Open Access Journals (Sweden)
Dong Yuan
2016-06-01
Full Text Available The thermal diode is the fundamental device for phononics. There are various mechanisms for thermal rectification, e.g. different temperature dependent thermal conductivity of two ends, asymmetric interfacial resistance, and nonlocal behavior of phonon transport in asymmetric structures. The phonon hydrodynamics and thermomass theory treat the heat conduction in a fluidic viewpoint. The phonon gas flowing through the media is characterized by the balance equation of momentum, like the Navier-Stokes equation for fluid mechanics. Generalized heat conduction law thereby contains the spatial acceleration (convection term and the viscous (Laplacian term. The viscous term predicts the size dependent thermal conductivity. Rectification appears due to the MFP supersession of phonons. The convection term also predicts rectification because of the inertia effect, like a gas passing through a nozzle or diffuser.
Alam, Mohosin; Mandal, Swapan; Wahiddin, Mohamed Ridza
2017-09-01
The essence of the rotating wave approximation (RWA) is to eliminate the non-conserving energy terms from the interaction Hamiltonian. The cost of using RWA is heavy if the frequency of the input radiation field is low (e.g. below optical region). The well known Bloch-Siegert effect is the out come of the inclusion of the terms which are normally neglected under RWA. We investigate the fluctuations of the quantum phase of the coherent light and the thermal light coupled to a nondegenerate parametric oscillator (NDPO). The Hamiltonian and hence the equations of motion involving the signal and idler modes are framed by using the strong (classical) pump condition. These differential equations are nonlinear in nature and are found coupled to each other. Without using the RWA, we obtain the analytical solutions for the signal and idler fields. These solutions are obtained up to the second orders in dimensionless coupling constants. The analytical expressions for the quantum phase fluctuation parameters due to Carruther's and Nieto are obtained in terms of the coupling constants and the initial photon numbers of the input radiation field. Moreover, we keep ourselves confined to the Pegg-Barnett formalism for measured phase operators. With and without using the RWA, we compare the quantum phase fluctuations for coherent and thermal light coupled to the NDPO. In spite of the significant departures (quantitative), the qualitative features of the phase fluctuation parameters for the input thermal light are identical for NDPO with and without RWA. On the other hand, we report some interesting results of input coherent light coupled to the NDPO which are substantially different from their RWA counterpart. In spite of the various quantum optical phenomena in a NDPO, we claim that it is the first effort where the complete analytical approach towards the solutions and hence the quantum phase fluctuations of input radiation fields coupled to it are obtained beyond rotating wave
Brandt, E. H.
1990-01-01
The levitation of high-T(sub c) superconductors is quite conspicuous: Above magnets of low symmetry a disk of these ceramics floats motionless, without vibration or rotation; it has a continuous range of stable positions and orientations as if it were stuck in sand. Some specimens may even be suspended above or below the same magnet. This fascinating stability, inherent to no other type of levitation, is caused by the pinning of magnetic flux lines by inhomogeneities inside these extreme type-2 superconductors. The talk deals with pinning of magnetic flux in these materials, with flux flow, flux creep, thermally activated depinning, and the thermal fluctuation of the vortex positions in the flux line lattice (often called flux lattice melting). Also discussed are the fluctuations of the (nearly periodic) magnetic field inside these superconductors which are caused by random pinning sites and by the finite temperature. These fluctuations broaden the van-Hove singularities observed in the density of the magnetic field by nuclear magnetic resonance and by muon spin rotation.
Marcucci, Lorenzo; Washio, Takumi; Yanagida, Toshio
2016-09-01
Muscle contractions are generated by cyclical interactions of myosin heads with actin filaments to form the actomyosin complex. To simulate actomyosin complex stable states, mathematical models usually define an energy landscape with a corresponding number of wells. The jumps between these wells are defined through rate constants. Almost all previous models assign these wells an infinite sharpness by imposing a relatively simple expression for the detailed balance, i.e., the ratio of the rate constants depends exponentially on the sole myosin elastic energy. Physically, this assumption corresponds to neglecting thermal fluctuations in the actomyosin complex stable states. By comparing three mathematical models, we examine the extent to which this hypothesis affects muscle model predictions at the single cross-bridge, single fiber, and organ levels in a ceteris paribus analysis. We show that including fluctuations in stable states allows the lever arm of the myosin to easily and dynamically explore all possible minima in the energy landscape, generating several backward and forward jumps between states during the lifetime of the actomyosin complex, whereas the infinitely sharp minima case is characterized by fewer jumps between states. Moreover, the analysis predicts that thermal fluctuations enable a more efficient contraction mechanism, in which a higher force is sustained by fewer attached cross-bridges.
Composition fluctuations in homopolymer blends and diblock copolymers
DEFF Research Database (Denmark)
Frielinghaus, H.; Mortensen, K.; Almdal, K.
2000-01-01
The thermal composition fluctuations of a deuterogenous polystyrene/polyethyleneoxide (dPS/PEO) homopolymer blend and corresponding diblock copolymer have been investigated by small angle neutron scattering (SANS). The measured susceptibilities could be described by theories, which take strong...
Torson, Alex S; Yocum, George D; Rinehart, Joseph P; Kemp, William P; Bowsher, Julia H
2015-04-01
The transcriptional responses of insects to long-term, ecologically relevant temperature stress are poorly understood. Long-term exposure to low temperatures, commonly referred to as chilling, can lead to physiological effects collectively known as chill injury. Periodically increasing temperatures during long-term chilling has been shown to increase survival in many insects. However, the transcripts responsible for this increase in survival have never been characterized. Here, we present the first transcriptome-level analysis of increased longevity under fluctuating temperatures during chilling. Overwintering post-diapause quiescent alfalfa leafcutting bees (Megachile rotundata) were exposed to a constant temperature of 6°C, or 6°C with a daily fluctuation to 20°C. RNA was collected at two different time points, before and after mortality rates began to diverge between temperature treatments. Expression analysis identified differentially regulated transcripts between pairwise comparisons of both treatments and time points. Transcripts functioning in ion homeostasis, metabolic pathways and oxidative stress response were up-regulated in individuals exposed to periodic temperature fluctuations during chilling. The differential expression of these transcripts provides support for the hypotheses that fluctuating temperatures protect against chill injury by reducing oxidative stress and returning ion concentrations and metabolic function to more favorable levels. Additionally, exposure to fluctuating temperatures leads to increased expression of transcripts functioning in the immune response and neurogenesis, providing evidence for additional mechanisms associated with increased survival during chilling in M. rotundata. © 2015. Published by The Company of Biologists Ltd.
Some applications of thermal field theory to quark-gluon plasma
Indian Academy of Sciences (India)
- ism, the hard thermal loop perturbation theory and some of its applications to the physics of the quark-gluon plasma, possibly created in relativistic heavy-ion collisions. Keywords. Thermal field theory; perturbative quantum chromodynamics; ...
Thermally Activated Post-glitch Response of the Neutron Star Inner Crust and Core. I. Theory
Link, Bennett
2014-07-01
Pinning of superfluid vortices is predicted to prevail throughout much of a neutron star. Based on the idea of Alpar et al., I develop a description of the coupling between the solid and liquid components of a neutron star through thermally activated vortex slippage, and calculate the response to a spin glitch. The treatment begins with a derivation of the vortex velocity from the vorticity equations of motion. The activation energy for vortex slippage is obtained from a detailed study of the mechanics and energetics of vortex motion. I show that the "linear creep" regime introduced by Alpar et al. and invoked in fits to post-glitch response is not realized for physically reasonable parameters, a conclusion that strongly constrains the physics of a post-glitch response through thermal activation. Moreover, a regime of "superweak pinning," crucial to the theory of Alpar et al. and its extensions, is probably precluded by thermal fluctuations. The theory given here has a robust conclusion that can be tested by observations: for a glitch in the spin rate of magnitude Δν, pinning introduces a delay in the post-glitch response time. The delay time is td = 7(t sd/104 yr)((Δν/ν)/10-6) d, where t sd is the spin-down age; td is typically weeks for the Vela pulsar and months in older pulsars, and is independent of the details of vortex pinning. Post-glitch response through thermal activation cannot occur more quickly than this timescale. Quicker components of post-glitch response, as have been observed in some pulsars, notably, the Vela pulsar, cannot be due to thermally activated vortex motion but must represent a different process, such as drag on vortices in regions where there is no pinning. I also derive the mutual friction force for a pinned superfluid at finite temperature for use in other studies of neutron star hydrodynamics.
Simple Theory of Thermal Fatigue Caused by RF Pulse Heating
Kuzikov, S
2004-01-01
The projects of electron-positron linear colliders imply that accelerating structures and other RF components will undergo action of extremely high RF fields. Except for breakdown threat there is an effect of the damage due to multi-pulse mechanical stress caused by Ohmic heating of the skin layer. A new theory of the thermal fatigue is considered. The theory is based on consideration of the quasi-elastic interaction between neighbor grains of metal due to the expansion of the thermal skin-layer. The developed theory predicts a total number of the RF pulses needed for surface degradation in dependence on temperature rise, pulse duration, and average temperature. The unknown coefficients in the final formula were found, using experimental data obtained at 11.4 GHz for the copper. In order to study the thermal fatigue at higher frequencies and to compare experimental and theoretical results, the experimental investigation of degradation of the copper cavity exposed to 30 GHz radiation is carried out now, basing...
Computer simulation of laser photon fluctuations - Theory of single-cavity laser
Marcuse, D.
1984-10-01
The reliability of data transmission in optical fiber systems using pulse code modulation is limited by photon fluctuations and mode hopping of injection lasers. It has been found that the fluctuations of laser light depend critically on the type of laser which is being used. For this reason, the development of mathematical models for predicting the fluctuations of the light output of different types of lasers is important for laser design applications. The approach to laser fluctuation studies considered in the present investigation is concerned with a description in terms of multimode, stochastic, and noise driven rate equations. A direct calculation of photon probability distributions is not possible with this approach. However, statistical information can be collected. This paper is concerned with the mathematical tools needed for the numerical solution of the problem. The rate equations are listed, and a description is provided regarding their numerical integration on a computer.
Theory and application of Detrended Fluctuation Analysis for "gappy" time series
Løvsletten, Ola
2016-04-01
A new theorem is presented which shows that the fluctuation function in detrended fluctuation analysis (DFA) can be written as a weighted sum of variograms (or second order structure functions). From this theorem we derive a new estimator for the fluctuation function, which can properly handle missing values in regularly sampled time series. Under mild conditions on the distribution of gaps, the new estimator is equal in expectation to the corresponding fluctuation function in the gap-free case. In the gap-free case these two estimators coincide. In addition to a description of the algorithm for this new DFA estimator and its theoretical foundation, application to geophysical time series with missing data will be presented.
Energy Technology Data Exchange (ETDEWEB)
Miyazaki, Kunimasa; Reichman, David R [Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027 (United States)
2005-05-20
In this letter, we develop a mode-coupling theory for a class of nonlinear Langevin equations with multiplicative noise using a field-theoretic formalism. These equations are simplified models of realistic colloidal suspensions. We prove that the derived equations are consistent with the fluctuation-dissipation theorem. We also discuss the generalization of the result given here to real fluids, and the possible description of supercooled fluids in the ageing regime. We demonstrate that the standard idealized mode-coupling theory is not consistent with the FDT in a strict field-theoretic sense. (letter to the editor)
Alvarez-Paggi, Damian; Zitare, Ulises; Murgida, Daniel H
2014-07-01
In this overview we present recent combined electrochemical, spectroelectrochemical, spectroscopic and computational studies from our group on the electron transfer reactions of cytochrome c and of the primary electron acceptor of cytochrome c oxidase, the CuA site, in biomimetic complexes. Based on these results, we discuss how protein dynamics and thermal fluctuations may impact on protein ET reactions, comment on the possible physiological relevance of these results, and finally propose a regulatory mechanism that may operate in the Cyt/CcO electron transfer reaction in vivo. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Copyright © 2014 Elsevier B.V. All rights reserved.
Thermalization and confinement in strongly coupled gauge theories
Directory of Open Access Journals (Sweden)
Ishii Takaaki
2016-01-01
Full Text Available Quantum field theories of strongly interacting matter sometimes have a useful holographic description in terms of the variables of a gravitational theory in higher dimensions. This duality maps time dependent physics in the gauge theory to time dependent solutions of the Einstein equations in the gravity theory. In order to better understand the process by which “real world” theories such as QCD behave out of thermodynamic equilibrium, we study time dependent perturbations to states in a model of a confining, strongly coupled gauge theory via holography. Operationally, this involves solving a set of non-linear Einstein equations supplemented with specific time dependent boundary conditions. The resulting solutions allow one to comment on the timescale by which the perturbed states thermalize, as well as to quantify the properties of the final state as a function of the perturbation parameters. We comment on the influence of the dual gauge theory’s confinement scale on these results, as well as the appearance of a previously anticipated universal scaling regime in the “abrupt quench” limit.
Resource theory of quantum states out of thermal equilibrium.
Brandão, Fernando G S L; Horodecki, Michał; Oppenheim, Jonathan; Renes, Joseph M; Spekkens, Robert W
2013-12-20
The ideas of thermodynamics have proved fruitful in the setting of quantum information theory, in particular the notion that when the allowed transformations of a system are restricted, certain states of the system become useful resources with which one can prepare previously inaccessible states. The theory of entanglement is perhaps the best-known and most well-understood resource theory in this sense. Here, we return to the basic questions of thermodynamics using the formalism of resource theories developed in quantum information theory and show that the free energy of thermodynamics emerges naturally from the resource theory of energy-preserving transformations. Specifically, the free energy quantifies the amount of useful work which can be extracted from asymptotically many copies of a quantum system when using only reversible energy-preserving transformations and a thermal bath at fixed temperature. The free energy also quantifies the rate at which resource states can be reversibly interconverted asymptotically, provided that a sublinear amount of coherent superposition over energy levels is available, a situation analogous to the sublinear amount of classical communication required for entanglement dilution.
Energy Technology Data Exchange (ETDEWEB)
Shaing, K.C. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (USA))
1990-04-01
The effects of the radial electric field {ital E}{sub {ital r}} on fluctuation-induced transport fluxes and the fluctuation spectrum in toroidal plasmas are further studied to clarify the ideas originally developed in an earlier paper (Phys. Fluids {bold 31}, 2249 (1988)). A specific tokamak example is employed in the discussion. It is found that even in the presence of fluctuations, the parallel flow in tokamaks is damped by the neoclassical viscosity on a time scale of the order of {nu}{sub {ital ii}}{sup {minus}1}, with {nu}{sub {ital ii}} the collision frequency. The toroidal flow is damped by the anomalous ion viscosity on a time scale of the order of the confinement time. The radial electric field always has an effect on the fluctuation spectrum and fluctuation-induced transport fluxes in tokamaks except when {ital d}({ital E}{sub {ital r}}q/{ital r})/{ital dr}=0 (where {ital q} is the safety factor and {ital r} is the minor radius) if the radial dependence of the toroidal magnetic field is neglected by considering the invariant property of the drift kinetic equation when there is a change in {ital E}{sub {ital r}}. The condition implies the rigid-body toroidal rotation associated with {bold E}{times}{bold B} drift, with {bold E} ({bold B}) the electric (magnetic) field. The fact that the fluctuation-induced transport fluxes can depend on {ital E}{sub {ital r}} through the fluctuation spectrum and the thermodynamic force does not contradict their intrinsic ambipolarity property. The results are shown to be invariant under Galilean transformation.
Effect of Thermal Fluctuations on the Radiative Rate in Core/Shell Quantum Dots.
Balan, Arunima D; Eshet, Hagai; Olshansky, Jacob H; Lee, Youjin V; Rabani, Eran; Alivisatos, A Paul
2017-03-08
The effect of lattice fluctuations and electronic excitations on the radiative rate is demonstrated in CdSe/CdS core/shell spherical quantum dots (QDs). Using a combination of time-resolved photoluminescence spectroscopy and atomistic simulations, we show that lattice fluctuations can change the radiative rate over the temperature range from 78 to 300 K. We posit that the presence of the core/shell interface plays a significant role in dictating this behavior. We show that the other major factor that underpins the change in radiative rate with temperature is the presence of higher energy states corresponding to electron excitation into the shell. These effects should be present in other core/shell samples and should also affect other excited state rates, such as the rate of Auger recombination or the rate of charge transfer.
Shaifer, J.
2016-02-01
The mummichog (Fundulus hetereoclitus) is an intertidal spawning fish that ranges from the Gulf of St. Lawrence to northeastern Florida. A notoriously hardy species, adults can tolerate a wide range of temperature typical of inshore, estuarine waters. This experiment assessed how a wide range of constant and fluctuating temperatures affect the survival, development, and condition of embryos and young larvae. Captive adults were provided nightly with spawning substrates that were inspected each morning for fertilized eggs. Young ( 8 hr post-fertilization) embryos (N = 25 per population) were assigned to either one of a wide range of constant temperatures (8 to 34 °C) generated by a thermal gradient block (TGB), or to one of 10 daily oscillating temperature regimes that spanned the TGB's mid temperature (21 °C). Water was changed and populations inspected for mortalities and hatching at 12-hr intervals. Hatch dates and mortalities were recorded, and larvae were either anesthetized and measured for size by analyzing digital images, or evaluated for persistence in a food-free environment. Mummichog embryos withstood all but the coldest constant regimes and the entire range of fluctuating ones although age at hatching varied substantially within and among experimental populations. Embryos incubated at warmer temperatures hatched out earlier and at somewhat smaller sizes than those experiencing cooler temperatures. Temperatures experienced by embryos had an inverse effect on persistence of larvae relying on yolk nutrition alone. Mummichog exhibited an especially plastic response to thermal challenges which reflects the highly variable nursery habitat used by this species.
Theory of low-temperature thermal expansion of glasses
Galperin, Yu. M.; Gurevich, V. L.; Parshin, D. A.
1985-11-01
We have developed a theory of low-temperature thermal expansion of glasses explaining a number of existing experimental data. We assume that thermal expansion, like many other low-temperature properties of glasses, is determined by associated two-level systems (TLS's) this concept has been introduced to explain these properties by Anderson, Halperin, and Varma and by Phillips. Our theory is based on the Karpov-Klinger-Ignat'ev model of two-level systems in glasses. The deformation potential of the TLS's is calculated. We have shown that it consists of two parts: The larger part (of the order of 0.3 eV) is responsible for the observed transport properties of glasses; however, it does not contribute to the thermal expansion of glasses. The latter is caused by a relatively small second part of the deformation potential which is, within logarithmic accuracy, proportional to the TLS's interlevel spacing E. This is why at low temperatures the coefficient of thermal expansion of glasses is approximately a linear function of the temperature. Its sign is determined by a microscopic structure of the TLS. We have calculated the Grüneisen parameter Γ. It appears to be of the order of (scrEa/ħωD)2/3~=100, where scrEa is an energy of the order of 30 eV and ωD is the Debye frequency. Such large values of Γ are connected with the softness of local anharmonic potentials that produce the TLS's in glasses. Our principal result is the dependence of the coefficient of thermal expansion α on the time of experiment, τexpt. It is shown that if α<0, then after heating glass it is at first contracted and afterwards, after the time about 10-8 sec (at T=0.3 K), a slow expansion begins. At τexpt~=1 sec the parameter Γ can have the absolute value of about (1/3) of that at τexpt~=10-8 sec. Such behavior of the thermal expansion coefficient is due to the fact that the contribution of the TLS's with large relative tunnel splitting (Δ0/E~=1) is negative while that of the TLS's with
Directory of Open Access Journals (Sweden)
Jan Fořt
2017-06-01
Full Text Available The current outdated state of many institutional and administrative buildings in the EU region poses a significant burden from the energy sustainability point of view. According to the contemporary EU requirements on the energy efficiency of buildings maintenance, an evaluation of performed improvements is essential for the assessment of expended investments. This paper describes the effect of building envelope reconstruction works consisting in the installation of a thermal insulation system. Here, a long-term continuous monitoring is used for the extensive assessment of the seasonal and daily temperature and relative humidity fluctuations. The obtained results include temperature and relative humidity profiles in the wall cross-section as a response to the changing exterior climatic conditions. The analysis of measured data reveals substantial improvements in thermal stability of the analyzed wall during temperature peaks. While the indoor temperatures exceeding 28 °C are recorded during summer before application of the thermal insulation layer, the thermal stability of the indoor environment is distinctly upgraded after performed improvements. Based on the complex long-term monitoring, a relevant experience is gained for the future work on energy sustainability and fulfilment of the EU directives.
Venner, Samuel; Pélisson, Pierre-François; Bel-Venner, Marie-Claude; Débias, François; Rajon, Etienne; Menu, Frédéric
2011-01-01
Background One major challenge in understanding how biodiversity is organized is finding out whether communities of competing species are shaped exclusively by species-level differences in ecological traits (niche theory), exclusively by random processes (neutral theory of biodiversity), or by both processes simultaneously. Communities of species competing for a pulsed resource are a suitable system for testing these theories: due to marked fluctuations in resource availability, the theories yield very different predictions about the timing of resource use and the synchronization of the population dynamics between the competing species. Accordingly, we explored mechanisms that might promote the local coexistence of phytophagous insects (four sister species of the genus Curculio) competing for oak acorns, a pulsed resource. Methodology/Principal Findings We analyzed the time partitioning of the exploitation of oak acorns by the four weevil species in two independent communities, and we assessed the level of synchronization in their population dynamics. In accordance with the niche theory, overall these species exhibited marked time partitioning of resource use, both within a given year and between different years owing to different dormancy strategies between species, as well as distinct demographic patterns. Two of the four weevil species, however, consistently exploited the resource during the same period of the year, exhibited a similar dormancy pattern, and did not show any significant difference in their population dynamics. Conclusions/Significance The marked time partitioning of the resource use appears as a keystone of the coexistence of these competing insect species, except for two of them which are demographically nearly equivalent. Communities of consumers of pulsed resources thus seem to offer a promising avenue for developing a unifying theory of biodiversity in fluctuating environments which might predict the co-occurrence, within the same community
Directory of Open Access Journals (Sweden)
Samuel Venner
Full Text Available BACKGROUND: One major challenge in understanding how biodiversity is organized is finding out whether communities of competing species are shaped exclusively by species-level differences in ecological traits (niche theory, exclusively by random processes (neutral theory of biodiversity, or by both processes simultaneously. Communities of species competing for a pulsed resource are a suitable system for testing these theories: due to marked fluctuations in resource availability, the theories yield very different predictions about the timing of resource use and the synchronization of the population dynamics between the competing species. Accordingly, we explored mechanisms that might promote the local coexistence of phytophagous insects (four sister species of the genus Curculio competing for oak acorns, a pulsed resource. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the time partitioning of the exploitation of oak acorns by the four weevil species in two independent communities, and we assessed the level of synchronization in their population dynamics. In accordance with the niche theory, overall these species exhibited marked time partitioning of resource use, both within a given year and between different years owing to different dormancy strategies between species, as well as distinct demographic patterns. Two of the four weevil species, however, consistently exploited the resource during the same period of the year, exhibited a similar dormancy pattern, and did not show any significant difference in their population dynamics. CONCLUSIONS/SIGNIFICANCE: The marked time partitioning of the resource use appears as a keystone of the coexistence of these competing insect species, except for two of them which are demographically nearly equivalent. Communities of consumers of pulsed resources thus seem to offer a promising avenue for developing a unifying theory of biodiversity in fluctuating environments which might predict the co-occurrence, within
Basics of thermal field theory a tutorial on perturbative computations
Laine, Mikko
2016-01-01
This book presents thermal field theory techniques, which can be applied in both cosmology and the theoretical description of the QCD plasma generated in heavy-ion collision experiments. It focuses on gauge interactions (whether weak or strong), which are essential in both contexts. As well as the many differences in the physics questions posed and in the microscopic forces playing a central role, the authors also explain the similarities and the techniques, such as the resummations, that are needed for developing a formally consistent perturbative expansion. The formalism is developed step by step, starting from quantum mechanics; introducing scalar, fermionic and gauge fields; describing the issues of infrared divergences; resummations and effective field theories; and incorporating systems with finite chemical potentials. With this machinery in place, the important class of real-time (dynamic) observables is treated in some detail. This is followed by an overview of a number of applications, ranging from t...
Stadler, A. M.; Garvey, C. J.; Bocahut, A.; Sacquin-Mora, S.; Digel, I.; Schneider, G. J.; Natali, F.; Artmann, G. M.; Zaccai, G.
2012-01-01
Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits. PMID:22696485
Spontaneous emission of Alfvénic fluctuations
Yoon, P. H.; López, R. A.; Vafin, S.; Kim, S.; Schlickeiser, R.
2017-09-01
Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvénic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvénic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Melnikov, N.B., E-mail: melnikov@cs.msu.su [Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Reser, B.I., E-mail: reser@imp.uran.ru [Miheev Institute of Metal Physics, Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Paradezhenko, G.V., E-mail: gparadezhenko@cs.msu.su [Lomonosov Moscow State University, Moscow 119991 (Russian Federation)
2016-08-01
To study the spin-density correlations in the ferromagnetic metals above the Curie temperature, we relate the spin correlator and neutron scattering cross-section. In the dynamic spin-fluctuation theory, we obtain explicit expressions for the effective and local magnetic moments and spatial spin-density correlator. Our theoretical results are demonstrated by the example of bcc Fe. The effective and local moments are found in good agreement with results of polarized neutron scattering experiment over a wide temperature range. The calculated short-range order is small (up to 4 Å) and slowly decreases with temperature.
DEFF Research Database (Denmark)
Christensen, Steen; Peters, Günther H.J.; Hansen, Flemming Yssing
2007-01-01
The ‘State Conditions Transferability’ category of IFPSC 2006 tests prediction of binary vapor–liquid isotherms for mixtures of ethanol and the refrigerant HFF-227ea (1,1,1,2,3,3,3-heptafluoropropane). We predict these isotherms using fluctuation solution theory (FST). The method is based......–457] comprise the nearly ideal benzene/methyl acetate system, and the less ideal benzene/ethanol system at ambient temperatures. Both are at low pressures and remote from the pure component critical points. For the IFPSC system, we have used the same method even though predictions are for conditions remote from...
Zeitler, Ralf; Fromherz, Peter
2013-05-21
The extracellular electrical interfacing of nerve cells with metals or semiconductors is governed by the resistance of the cell-solid junction. With snail neurons on a CMOS chip, we have probed the thermal voltage fluctuations in the junction at a spatial resolution of 7.4 μm in a spectral range from 10 Hz to 1 MHz using an array of sensor transistors. The power spectral density (PSD) could be interpreted in terms of a Johnson-Nyquist noise if the distributed nature of the cell-solid junction and the size of the sensors were taken into account. The PSD over the whole spectral range as well as its spatial profile were matched by the thermal noise of a circular core-coat conductor with a homogeneous sheet resistance in the range of 100 MΩ. The quantitative interpretation of the thermal noise in a cell-solid junction provides a basis for applications of this noninvasive method in the characterization of biosensoric and neuroprosthetic devices.
Energy Technology Data Exchange (ETDEWEB)
Zimmerman, E.G.; Richmond, M.C.
1981-05-01
Populations of a common forage fish, red shiner Notropis lutrensis, were sampled from four localities on the Brazos River, Texas, affected by cold-water discharge from a hydroelectric dam and from unaltered sites in the same region. Polymorphism at the Mdh-B locus, encoding supernatant malate dehydrogenase, indicates that populations within 57 km of the dam are distinctive from other regional populations and possess a unique Mdh-B allele, have significantly higher levels of heterozygosity at the Mdh-B locus, represent a homogeneous set that have significantly different Mdh-B zygotic frequencies from other regional populations, and have significantly different Mdh-B zygotic proportions than would be expected under a Hardy-Weinberg equilibrium. Increased levels of heterozygosity in fish within 57 km of the dam were correlated with discharge-associated fluctuations in water temperature at sampling stations.
Fluid-particle dynamics for passive tracers advected by a thermally fluctuating viscoelastic medium
Hohenegger, Christel; McKinley, Scott A.
2017-07-01
Many biological fluids, like mucus and cytoplasm, have prominent viscoelastic properties. As a consequence, immersed particles exhibit subdiffusive behavior, which is to say, the variance of the particle displacement grows sublinearly with time. In this work, we propose a viscoelastic generalization of the Landau-Lifschitz Navier-Stokes fluid model and investigate the properties of particles that are passively advected by such a medium. We exploit certain exact formulations that arise from the Gaussian nature of the fluid model and introduce analysis of memory in the fluid statistics, marking an important step toward capturing fluctuating hydrodynamics among subdiffusive particles. The proposed method is spectral, meshless and is based on the numerical evaluation of the covariance matrix associated with individual fluid modes. With this method, we probe a central hypothesis of passive microrheology, a field premised on the idea that the statistics of particle trajectories can reveal fundamental information about their surrounding fluid environment.
Thibodeau, Lise; Lachaud, James
2016-01-01
Three theories have been proposed to explain the relationship between suicide and economic fluctuations, including the Durkheim (nonlinear), Ginsberg (procyclical), and Henry and Short (countercyclical) theories. This study tested the effect of economic fluctuations, measured by unemployment rate, on suicide rates in Canada from 1926 to 2008. Autoregressive integrated moving average time-series models were used. The results showed a significant relationship between suicide and economic fluctuation; this association was positive during the contraction period (1926-1950) and negative in the period of economic expansion (1951-1973). Males and females showed differential effects in the period of moderate unemployment (1974-2008). In addition, the suicide rate of mid-adults (45-64) was most impacted by economic fluctuations. Our study tends to support Durkheim's theory and suggests the need for public health responses in times of economic contraction and expansion.
Gidoin, Cindy; Roques, Lionel; Boivin, Thomas
2015-03-01
Theories of species coexistence and invasion ecology are fundamentally connected and provide a common theoretical framework for studying the mechanisms underlying successful invasions and their ecological impacts. Temporal fluctuations in resource availability and differences in life-history traits between invasive and resident species are considered as likely drivers of the dynamics of invaded communities. Current critical issues in invasion ecology thus relate to the extent to which such mechanisms influence coexistence between invasive and resident species and to the ability of resident species to persist in an invasive-dominated ecosystem. We tested how a fluctuating resource, and species trait differences may explain and help predict long-term impacts of biological invasions in forest specialist insect communities. We used a simple invasion system comprising closely related invasive and resident seed-specialized wasps (Hymenoptera: Torymidae) competing for a well-known fluctuating resource and displaying divergent diapause, reproductive and phenological traits. Based on extensive long-term field observations (1977-2010), we developed a combination of mechanistic and statistical models aiming to (i) obtain a realistic description of the population dynamics of these interacting species over time, and (ii) clarify the respective contributions of fluctuation-dependent and fluctuation-independent mechanisms to long-term impact of invasion on the population dynamics of the resident wasp species. We showed that a fluctuation-dependent mechanism was unable to promote coexistence of the resident and invasive species. Earlier phenology of the invasive species was the main driver of invasion success, enabling the invader to exploit an empty niche. Phenology also had the greatest power to explain the long-term negative impact of the invasive on the resident species, through resource pre-emption. This study provides strong support for the critical role of species
Domain walls in thermal gauge field theories - myth or reality?
Energy Technology Data Exchange (ETDEWEB)
Smilga, A.V. [Bern Univ. (Switzerland). Inst. fuer Theoretische Physik]|[Gosudarstvennyj Komitet po Ispol`zovaniyu Atomnoj Ehnergii SSSR, Moscow (Russian Federation). Inst. Teoreticheskoj i Ehksperimental`noj Fiziki
1994-01-01
We argue different Z{sub N} thermal vacua of hot pure Yang-Mills theory distinguished in the standard approach by different values of Polyakov loop average
{sub T} corresponds actually to one and the same physical state. A critical discussion of the argument which are usually put forward in favor of the opposite conclusion (that, in pure continuum Yang-Mills theory, distinct Z{sub N}-phases may coexist in the physical space being separated by the domain walls finite surface energy) is given. In particular, we note that the same arguments can be applied with an equal ease to Abelian theories and would lead to the existence of the walls in the high-T 4-dim QED and to appearance of the queer high-T solitons with the mass {approx} T{sup 2}/e in the Schwinger model. We emphasize that these configurations may be relevant for the Euclidean path integral but whether they correspond to Minkowski space objects is unclear. (author). 16 refs, 2 figs.
The Schrödinger–Langevin equation with and without thermal fluctuations
Energy Technology Data Exchange (ETDEWEB)
Katz, R., E-mail: roland.katz@subatech.in2p3.fr; Gossiaux, P.B., E-mail: Pol-Bernard.Gossiaux@subatech.in2p3.fr
2016-05-15
The Schrödinger–Langevin equation (SLE) is considered as an effective open quantum system formalism suitable for phenomenological applications involving a quantum subsystem interacting with a thermal bath. We focus on two open issues relative to its solutions: the stationarity of the excited states of the non-interacting subsystem when one considers the dissipation only and the thermal relaxation toward asymptotic distributions with the additional stochastic term. We first show that a proper application of the Madelung/polar transformation of the wave function leads to a non zero damping of the excited states of the quantum subsystem. We then study analytically and numerically the SLE ability to bring a quantum subsystem to the thermal equilibrium of statistical mechanics. To do so, concepts about statistical mixed states and quantum noises are discussed and a detailed analysis is carried with two kinds of noise and potential. We show that within our assumptions the use of the SLE as an effective open quantum system formalism is possible and discuss some of its limitations.
Gunawardana, K. G. S. H.
The rapid development of nanotechnology has enabled the fabrication of structures much smaller than the mean free path of electrons and phonons. In modern electronics, miniaturization is desired to increase the transistor density and the clock speed. Electronic transport on the nanoscale has been studied for over three decades and fascinating quantum effects have been observed. Phonon transport on this scale is of significant interest because of the increased power dissipation in nanoelectronics, which undermines the correct functionality of devices and limits their lifetime. Apart from the effort to minimize heat generation, an efficient heat management scheme is necessary. Historically, thermal transport in bulk materials was described by the Fourier's law, in which the thermal conductivity is an intrinsic property of the material. Later a more descriptive model, the Boltzmann approach for thermal transport, was developed and could explain the thermal conductivity down to a 100 nm length scale at high temperatures. At low temperatures and in structures smaller than roughly 100 nm, thermal transport is described by the fully quantum mechanical Landauer- Butticker formalism. In this context, accurate calculation of phonon transmission probabilities is very important. In this dissertation, I develop a continuum model to calculate phonon transmission probabilities between media, which have high contrast in the elastic properties. In this work, we include an interface transition layer between the two media and look for interface properties that improve thermal transport. Secondly, I develop a new theoretical tool based on the R-Matrix theory to calculate phonon transmission probabilities on the atomic scale. R-matrix theory is a well developed theoretical approach commonly used in nuclear and atomic physics to solve scattering problems. Recently, this approach has been successfully developed to calculate electronic scattering in mesoscopic quantum devices. The key
Hamilton-Jacobi-Bellman theory of dissipative thermal availability
Sieniutycz, Stanislaw
1997-11-01
We analyze a steady-state problem of maximum work delivered from a finite resource fluid and a bath, as the dissipative, finite-time generalization of the evolutionary Carnot problem in which the temperature driving force between two interacting subsystems varies with the contact time. The thermal capacity of the bath is very large, so its intensive parameters do not change. At the classical, reversible limit, the instantaneous rates do vanish due to the reversibility requirement, whereas in the generalized problem some inherent, rate-related irreversibilities are inevitable, in particular those occurring in boundary layers at interfaces. Methods of the optimal control and variational calculus are suitable to optimize nonlinear dynamics of the process. An analytical formalism, strongly analogous to those in analytical mechanics and optimal control theory, is effective in thermodynamic optimization. A variational theory treats an infinite sequence of infinitesimal Curzon-Ahlborn-Novikov processes as the theoretical model pertinent to develop the theory of a finite-resource fluid interacting with a bath in a finite time, when the active exchange of the energy occurs through the working fluid of participating engines, refrigerators, or heat pumps. The main application is the extension of the classical availability (exergy) beyond the class of reversible processes. The generalized exergy is next discussed in terms of the finite intensity and finite duration of the process. Optimality of a definite irreversible process is an essential feature for a finite duration. A link is shown between the process duration and the optimal intensity measured in terms of a dissipative Hamiltonian. An interesting approach, based on the Hamilton-Jacobi-Bellman equation for the irreversible availability and underlying work functionals (HJB theory), is developed. The HJB formulation is suitable for generation of numerical data of the work potentials, by the standard recurrence equation of
Microbial community dynamics in Inferno Crater Lake, a thermally fluctuating geothermal spring.
Ward, Laura; Taylor, Michael W; Power, Jean F; Scott, Bradley J; McDonald, Ian R; Stott, Matthew B
2017-05-01
Understanding how microbial communities respond and adjust to ecosystem perturbation is often difficult to interpret due to multiple and often simultaneous variations in observed conditions. In this research, we investigated the microbial community dynamics of Inferno Crater Lake, an acidic geothermal spring in New Zealand with a unique thermal cycle that varies between 30 and 80 °C over a period of 40-60 days. Using a combination of next-generation sequencing, geochemical analysis and quantitative PCR we found that the microbial community composition was predominantly chemolithotrophic and strongly associated with the thermal cycle. At temperatures >65 °C, the microbial community was dominated almost exclusively by sulphur-oxidising archaea (Sulfolobus-like spp.). By contrast, at mesophilic temperatures the community structure was more mixed, comprising both archaea and bacteria but dominated primarily by chemolithotrophic sulphur and hydrogen oxidisers. Multivariate analysis of physicochemical data confirmed that temperature was the only significant variable associated with community turnover. This research contributes to our understanding of microbial community dynamics in variable environments, using a naturally alternating system as a model and extends our limited knowledge of acidophile ecology in geothermal habitats.
Theory of spin-fluctuation induced superconductivity in iron-based superconductors
Energy Technology Data Exchange (ETDEWEB)
Zhang, Junhua [Iowa State Univ., Ames, IA (United States)
2011-01-01
In this dissertation we focus on the investigation of the pairing mechanism in the recently discovered high-temperature superconductor, iron pnictides. Due to the proximity to magnetic instability of the system, we considered short-range spin fluctuations as the major mediating source to induce superconductivity. Our calculation supports the magnetic fluctuations as a strong candidate that drives Cooper-pair formation in this material. We find the corresponding order parameter to be of the so-called ss-wave type and show its evolution with temperature as well as the capability of supporting high transition temperature up to several tens of Kelvin. On the other hand, our itinerant model calculation shows pronounced spin correlation at the observed antiferromagnetic ordering wave vector, indicating the underlying electronic structure in favor of antiferromagnetic state. Therefore, the electronic degrees of freedom could participate both in the magnetic and in the superconducting properties. Our work shows that the interplay between magnetism and superconductivity plays an important role to the understanding of the rich physics in this material. The magnetic-excitation spectrum carries important information on the nature of magnetism and the characteristics of superconductivity. We analyze the spin excitation spectrum in the normal and superconducting states of iron pnictides in the magnetic scenario. As a consequence of the sign-reversed gap structure obtained in the above, a spin resonance mode appears below the superconducting transition temperature. The calculated resonance energy, scaled with the gap magnitude and the magnetic correlation length, agrees well with the inelastic neutron scattering (INS) measurements. More interestingly, we find a common feature of those short-range spin fluctuations that are capable of inducing a fully gapped ss state is the momentum anisotropy with elongated span along the direction transverse to the antiferromagnetic momentum
Thermal stresses and deflections of cross-ply laminated plates using refined plate theories
Khdeir, A. A.; Reddy, J. N.
1991-01-01
Exact analytical solutions of refined plate theories are developed to study the thermal stresses and deflections of cross-ply rectangular plates. The state-space approach in conjunction with the Levy method is used to solve exactly the governing equations of the theories under various boundary conditions. Numerical results of the higher-order theory of Reddy for thermal stresses and deflections are compared with those obtained using the classical and first-order plate theories.
Directory of Open Access Journals (Sweden)
Malykin G. B.
2009-01-01
Full Text Available Israel L. Bershtein (1908-2000 was one of the famous radio physicists in the world. He had constructed the theory of amplitude and frequency fluctuations for the electromagnetic wave generators working in the radio and optical scales. He also had developed numerous methods for precise measurement of the fluctuations, which also can be applied to ultimate small mechanical displacements. Besides these he was the first person among the scientists, who had registered the Sagnac effect at radiowaves.
DEFF Research Database (Denmark)
Shapiro, Alexander
2004-01-01
The theory of transport properties in multicomponent gas and liquid mixtures, which was previously developed for diffusion coefficients, is extended onto thermodiffusion coefficients and heat conductivities. The derivation of the expressions for transport properties is based on the general...... of the heat conductivity coefficient for ideal gas. (C) 2003 Elsevier B.V. All rights reserved....
Cosmological Inflation with Multiple Fields and the Theory of Density Fluctuations
Tent, B.J.W. van
2002-01-01
Inflation is a stage of extremely rapid expansion in the very early universe. It was proposed to solve a number of problems in the standard Big Bang theory. In particular it others an explanation for the origin of structures like (clusters of) galaxies on the one hand (by generating small density
Thermal fluctuations and stability of a particle levitated by a repulsive Casimir force in a liquid.
Inui, Norio; Goto, Kosuke
2013-11-01
We study the vertical Brownian motion of a gold particle levitated by a repulsive Casimir force to a silica plate immersed in bromobenzene. The time evolution of the particle distribution starting from an equilibrium position, where the Casimir force and gravitational force are balanced, is considered by solving the Langevin equation using the Monte Carlo method. When the gold particle is very close to the silica plate, the Casimir force changes from repulsive to attractive, and the particle eventually sticks to the surface. The escape rate from a metastable position is calculated by solving the Fokker-Plank equation; it agrees with the value obtained by Kramers' escape theory. The duration of levitation increases as the particle radius increases up to around 2.3 μm. As an example, we show that a 1-μm-diameter gold particle can be levitated for a significantly long time by the repulsive Casimir force at room temperature.
Dai, Gaole; Shang, Jin; Huang, Jiping
2018-02-01
Heat can transfer via thermal conduction, thermal radiation, and thermal convection. All the existing theories of transformation thermotics and optics can treat thermal conduction and thermal radiation, respectively. Unfortunately, thermal convection has seldom been touched in transformation theories due to the lack of a suitable theory, thus limiting applications associated with heat transfer through fluids (liquid or gas). Here, we develop a theory of transformation thermal convection by considering the convection-diffusion equation, the equation of continuity, and the Darcy law. By introducing porous media, we get a set of equations keeping their forms under coordinate transformation. As model applications, the theory helps to show the effects of cloaking, concentrating, and camouflage. Our finite-element simulations confirm the theoretical findings. This work offers a transformation theory for thermal convection, thus revealing novel behaviors associated with potential applications; it not only provides different hints on how to control heat transfer by combining thermal conduction, thermal convection, and thermal radiation, but also benefits mass diffusion and other related fields that contain a set of equations and need to transform velocities at the same time.
Cabrera-Trujillo, José Manuel; Martín Montejano-Carrizales, Juan; Aguilera-Granja, Faustino; Posada-Amarillas, Álvaro
2015-07-01
A reactive potential model and the classical molecular dynamics method (RMD) have been used to study the structure and energetics of sub-nanometre size gold clusters through well-known structural models reported in the literature for AuN, with N = 19, 20 and 21 atoms. After several simulated-annealing simulations for temperatures up to 1500 K, the AuN clusters clearly evolve to well-defined structures at room temperature. For the studied gold clusters, the low-lying structures are single- and double-icosahedra with mobile atoms on the surface, in agreement with experimental results on sub-nanometre size gold clusters exhibiting shape oscillations at room temperature and also with those involved in the design of molecules based on gold superatoms [J.-I. Nishigaki, K. Koyasu, T. Tsukuda, Chem. Rec. 14, 897 (2014)]. The evolution of the structural stability of the AuN clusters under exceptional thermal conditions is analysed by comparing the size and temperature variations of the centrosymmetry parameter and the potential energy. A key understanding of the various possible structural changes undergone by these tiny particles is thus developed. The usefulness of the RMD to study nanometre or sub-nanometre size gold clusters is shown.
Effective field theory of an anomalous Hall metal from interband quantum fluctuations
Chua, Victor; Assawasunthonnet, Wathid; Fradkin, Eduardo
2017-07-01
We construct an effective field theory, a two-dimensional two-component metallic system described by a model with two Fermi surfaces ("pockets"). This model describes a translationally invariant metallic system with two types of fermions, each with its own Fermi surface, with forward scattering interactions. This model, in addition to the O (2 ) rotational invariance, has a U (1 )×U (1 ) symmetry of separate charge conservation for each Fermi surface. For sufficiently attractive interactions in the d -wave (quadrupolar) channel, this model has an interesting phase diagram that includes a spontaneously generated anomalous Hall metal phase. We derive the Landau-Ginzburg effective action of quadrupolar order parameter fields which enjoys an O (2 )×U (1 ) global symmetry associated to spatial isotropy and the internal U (1 ) relative phase symmetries, respectively. We show that the order parameter theory is dynamically local with a dynamical scaling of z =2 and perform a one-loop renormalization group analysis of the Landau-Ginzburg theory. The electronic liquid crystal phases that result from spontaneous symmetry breaking are studied and we show the presence of Landau damped Nambu-Goldstone modes at low momenta that is a signature of non-Fermi-liquid behavior. Electromagnetic linear response is also analyzed in both the normal and symmetry broken phases from the point of view of the order parameter theory. The nature of the coupling of electromagnetism to the order parameter fields in the normal phase is non-minimal and decidedly contains a precursor to the anomalous Hall response in the form of a order-parameter-dependent Chern-Simons term in the effective action.
The Halo Mass Function from Excursion Set Theory. III. Non-Gaussian Fluctuations
Maggiore, Michele
2010-01-01
We compute the effect of primordial non-Gaussianity on the halo mass function, using excursion set theory. In the presence of non-Gaussianity the stochastic evolution of the smoothed density field, as a function of the smoothing scale, is non-markovian and beside "local" terms that generalize Press-Schechter (PS) theory, there are also "memory" terms, whose effect on the mass function can be computed using the formalism developed in the first paper of this series. We find that, when computing the effect of the three-point correlator on the mass function, a PS-like approach which consists in neglecting the cloud-in-cloud problem and in multiplying the final result by a fudge factor close to 2, is in principle not justified. When computed correctly in the framework of excursion set theory, in fact, the "local" contribution vanishes (for all odd-point correlators the contribution of the image gaussian cancels the Press-Schechter contribution rather than adding up), and the result comes entirely from non-trivial ...
Fluctuation theorems for quantum processes.
Albash, Tameem; Lidar, Daniel A; Marvian, Milad; Zanardi, Paolo
2013-09-01
We present fluctuation theorems and moment generating function equalities for generalized thermodynamic observables and quantum dynamics described by completely positive trace preserving maps, with and without feedback control. Our results include the quantum Jarzynski equality and Crooks fluctuation theorem, and clarify the special role played by the thermodynamic work and thermal equilibrium states in previous studies. We show that for a specific class of generalized measurements, which include projective measurements, unitality replaces microreversibility as the condition for the physicality of the reverse process in our fluctuation theorems. We present an experimental application of our theory to the problem of extracting the system-bath coupling magnitude, which we do for a system of pairs of coupled superconducting flux qubits undergoing quantum annealing.
Fluctuation theorems for quantum processes
Albash, Tameem; Lidar, Daniel A.; Marvian, Milad; Zanardi, Paolo
2013-09-01
We present fluctuation theorems and moment generating function equalities for generalized thermodynamic observables and quantum dynamics described by completely positive trace preserving maps, with and without feedback control. Our results include the quantum Jarzynski equality and Crooks fluctuation theorem, and clarify the special role played by the thermodynamic work and thermal equilibrium states in previous studies. We show that for a specific class of generalized measurements, which include projective measurements, unitality replaces microreversibility as the condition for the physicality of the reverse process in our fluctuation theorems. We present an experimental application of our theory to the problem of extracting the system-bath coupling magnitude, which we do for a system of pairs of coupled superconducting flux qubits undergoing quantum annealing.
Maximum-Likelihood Approach to Topological Charge Fluctuations in Lattice Gauge Theory
Brower, R C; Fleming, G T; Lin, M F; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Voronov, G; Vranas, P; Weinberg, E; Witzel, O
2014-01-01
We present a novel technique for the determination of the topological susceptibility (related to the variance of the distribution of global topological charge) from lattice gauge theory simulations, based on maximum-likelihood analysis of the Markov-chain Monte Carlo time series. This technique is expected to be particularly useful in situations where relatively few tunneling events are observed. Restriction to a lattice subvolume on which topological charge is not quantized is explored, and may lead to further improvement when the global topology is poorly sampled. We test our proposed method on a set of lattice data, and compare it to traditional methods.
DEFF Research Database (Denmark)
Jørgensen, E.; Koshelets, V. P.; Monaco, Roberto
1982-01-01
The radiation emission from long and narrow Josephson tunnel junctions dc-current biased on zero-field steps has been ascribed to resonant motion of fluxons on the transmission line. Within this dynamic model a theoretical expression for the radiation linewidth is derived from a full statistical...
Sensitivity theory applied to a transient thermal-hydraulics problem
Energy Technology Data Exchange (ETDEWEB)
Weber, C.F.; Oblow, E.M.
1979-10-01
A new method for sensitivity analysis of transient nonlinear problems is developed and applied to a reactor thermal-hydraulics problem. The method resembles the differential sensitivity methods currently used in the linear problems of reactor physics, but it is applicable to nonlinear systems as well. The equations governing heat transfer and fluid flow in a fuel pin and surrounding coolant are given and used to derive a second set of equations (commonly known as the adjoint equations) used in the sensitivity analysis. Both systems contain one second-order parabolic and one first-order hyperbolic partial differential equation. Difference equations are derived to approximate both systems and the convergence properties of these discrete systems are evaluated, yielding a useful analysis of the numerical solution. The solution functions are used to derive sensitivity coefficients for any desired integral response. These sensitivity coefficients are used in a first-order perturbation theory to predict changes in a response resulting from changes in parameter values. The results of a test problem are shown, verifying that this procedure is indeed useful for a wide variety of sensitivity calculations.
Primordial fluctuations from inflation in dRGT bimetric theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Sakakihara, Yuki [Department of Physics, Kyoto University,Kyoto 606-8502 (Japan); Research Center for the Early Universe (RESCEU), Graduate School of Science,The University of Tokyo, Tokyo 113-0033 (Japan); Tanaka, Takahiro [Department of Physics, Kyoto University,Kyoto 606-8502 (Japan); Yukawa Institute for Theoretical Physics, Kyoto University,Kyoto 606-8502 (Japan)
2016-09-19
We investigate primordial gravitational waves and curvature perturbations in de Rham-Gabadadze-Tolley (dRGT) bimetric gravity. We evaluate the power-spectra in the leading order in slow roll. Taking into account the decay of massive graviton, we find that the action up to the second order reduces to the Einstein theory with a non-minimally coupled scalar field, which is simplified to a minimally coupled model by conformal transformation. We also find that the tensor to scalar ratio for large field inflation with power law potential is larger than the general relativity counterpart for any choice of parameters in dRGT bimetric gravity. In addition, we confirm that the usual consistency relation holds and we have a steeper spectrum for gravitational waves.
Tsang, L.; Newton, R. W.; Kong, J. A.
1982-01-01
The strong fluctuation random medium theory is applied to calculate scattering from a half-space of dielectric mixture. The first and second moments of the fields are calculated, respectively, by using the bilocal and the distorted Born approximations, and the low frequency limit is taken. The singularity of the dyadic Green's function is taken into account. Expressions for the effective permittivity for the full space case are derived. It is shown that the derived result of the effect permittivity is identical to that of the Polder and van Santern mixing formula. The correlation function of the random medium is obtained by using simple physical arguments and is expressed in terms of the fractional volumes and particle sizes of the constituents of the mixture. Backscattering coefficients of a half-space dielectric mixture are also calculated. Numerical results of the effective permittivity and backscattering coefficients are illustrated using typical parameters encountered in microwave remote sensing of dry and wet snow. It is also shown that experimental data can be matched with the theory by using physical parameters of the medium as obtained from ground truth measurements.
Surface Tension of Acid Solutions: Fluctuations beyond the Nonlinear Poisson-Boltzmann Theory.
Markovich, Tomer; Andelman, David; Podgornik, Rudi
2017-01-10
We extend our previous study of surface tension of ionic solutions and apply it to acids (and salts) with strong ion-surface interactions, as described by a single adhesivity parameter for the ionic species interacting with the interface. We derive the appropriate nonlinear boundary condition with an effective surface charge due to the adsorption of ions from the bulk onto the interface. The calculation is done using the loop-expansion technique, where the zero loop (mean field) corresponds of the full nonlinear Poisson-Boltzmann equation. The surface tension is obtained analytically to one-loop order, where the mean-field contribution is a modification of the Poisson-Boltzmann surface tension and the one-loop contribution gives a generalization of the Onsager-Samaras result. Adhesivity significantly affects both contributions to the surface tension, as can be seen from the dependence of surface tension on salt concentration for strongly absorbing ions. Comparison with available experimental data on a wide range of different acids and salts allows the fitting of the adhesivity parameter. In addition, it identifies the regime(s) where the hypotheses on which the theory is based are outside their range of validity.
New Insight into Short-Wavelength Solar Wind Fluctuations from Vlasov Theory
Sahraoui, Fouad; Belmont, G.; Goldstein, M. L.
2012-01-01
The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfven waves (KAWs) at sub-ion scales with omega omega (sub ci)) is more relevant. Here, we study key properties of the short-wavelength plasma modes under limited, but realistic, SW conditions, Typically Beta(sub i) approx. > Beta (sub e) 1 and for high oblique angles of propagation 80 deg theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfven mode (known in the magnetohydrodynamic limit) extends at scales kappa rho (sub i) approx. > 1 to frequencies either larger or smaller than omega (sub ci), depending on the anisotropy kappa (parallel )/ kappa(perpendicular). This extension into small scales is more readily called whistler (omega > omega (sub ci)) or KAW (omega < omega (sub ci)) although the mode is essentially the same. This contrasts with the well-accepted idea that the whistler branch always develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter the more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small-scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.
Thermal flexural analysis of cross-ply laminated plates using trigonometric shear deformation theory
Directory of Open Access Journals (Sweden)
Yuwaraj Marotrao Ghugal
Full Text Available Thermal stresses and displacements for orthotropic, two-layer antisymmetric, and three-layer symmetric square cross-ply laminated plates subjected to nonlinear thermal load through the thickness of laminated plates are presented by using trigonometric shear deformation theory. The in-plane displacement field uses sinusoidal function in terms of thickness co-ordinate to include the shear deformation effect. The theory satisfies the shear stress free boundary conditions on the top and bottom surfaces of the plate. The present theory obviates the need of shear correction factor. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The validity of present theory is verified by comparing the results with those of classical plate theory and first order shear deformation theory and higher order shear deformation theory.
Manning, Robert M.
2011-01-01
An expression for the mutual coherence function (MCF) of an electromagnetic beam wave propagating through atmospheric turbulence is derived within the confines of the Rytov approximation. It is shown that both the first and second Rytov approximations are required. The Rytov MCF is then compared to that which issues from the parabolic equation method of strong fluctuation theory. The agreement is found to be quite good in the weak fluctuation case. However, an instability is observed for the special case of beam wave intensities. The source of the instabilities is identified to be the characteristic way beam wave amplitudes are treated within the Rytov method.
Fedorov, Dmitri G; Kitaura, Kazuo
2018-02-15
Pair interaction energy decomposition analysis in the fragment molecular orbital (FMO) method is extended to treat density functional theory (DFT) and density-functional tight-binding (DFTB). Fluctuations of energy contributions are obtained from molecular dynamics simulations. Interactions at the DFT and DFTB levels are compared to the values obtained with Hartree-Fock, second-order Møller-Plesset (MP2), and coupled cluster methods. Hydrogen bonding in water clusters is analyzed. 200 ps NVT molecular dynamics simulations are performed with FMO for two ligands bound to the Trp-cage miniprotein (PDB 1L2Y ); the fluctuations of fragment energies and interactions are analyzed.
Theory of the dynamical thermal conductivity of metals
Bhalla, Pankaj; Kumar, Pradeep; Das, Nabyendu; Singh, Navinder
2016-09-01
The Mori's projection method, known as the memory function method, is an important theoretical formalism to study various transport coefficients. In the present work, we calculate the dynamical thermal conductivity in the case of metals using the memory function formalism. We introduce thermal memory functions for the first time and discuss the behavior of thermal conductivity in both the zero frequency limit and in the case of nonzero frequencies. We compare our results for the zero frequency case with the results obtained by the Bloch-Boltzmann kinetic approach and find that both approaches agree with each other. Motivated by some recent experimental advancements, we obtain several new results for the ac or the dynamical thermal conductivity.
Thermal Renormalization Group-Equations and the Phase-Transition of Scalar O(N)-Theories
Bergerhoff, Bastian; Reingruber, Juergen
1998-01-01
We discuss the formulation of "thermal renormalization group-equations" and their application to the finite temperature phase-transition of scalar O(N)-theories. Thermal renormalization group-equations allow for a computation of both the universal and the non-universal aspects of the critical behavior directly in terms of the zero-temperature physical couplings. They provide a nonperturbative method for a computation of quantities like real-time correlation functions in a thermal environment,...
Vinas, A. F.; Adrian, M. L.; Moya, P. S.; Wendel, D. E.
2015-12-01
The solar wind electron velocity distribution function (eVDF) displays a great variety of non-thermal features (e.g., core, halo and strahl electron populations; with superposition of different temperatures, thermal anisotropies, suprathermal tails, beam-like features, etc.) that deviate from thermal equilibrium. These electron nonthermal deviations provide a local source for whistler-cyclotron and firehose instabilities electromagnetic fluctuations that are commonly observed. We present clear observational evidence that the temperature anisotropy whistler instability threshold, of a nonthermal kappa distribution plasma, marginally bounds solar wind magnetic fluctuations — when the full electron distribution is considered, without regard of separation of the various electron components during slow solar wind periods. Analysis seems to suggest that during slow solar wind periods, collisional effects are dominant. During fast solar wind periods, magnetic fluctuations and solar wind anisotropies are enhanced above the parallel whistler anisotropic threshold boundary and collisional effects are drastically reduced. Preliminary calculations further show that the oblique electron whistler mirror anisotropic instability bounds both the slow and fast solar wind. Regardless of solar wind speed, the solar wind electron thermal anisotropy appears globally bounded by the parallel electron firehose instability for anisotropies Te⊥ / Te|| < 1 indicative of a firehose-stable electron plasma. Preliminary analysis suggests that skew-kappa nonthermal distributions also shows marginally stable threshold boundaries when considering electron heat flux instability thresholds. The results of our analysis suggests that the slow solar wind electron plasma, when considered globally as a single eVDF, is only marginally stable with respect to nonthermal skew kappa distributions and parallel propagating instabilities.
Analytical Thermal Field Theory Applicable to Oil Hydraulic Fluid Film Lubrication
DEFF Research Database (Denmark)
Johansen, Per; Roemer, Daniel Beck; Pedersen, Henrik C.
2014-01-01
An analytical thermal field theory is derived by a perturbation series expansion solution to the energy conservation equation. The theory is valid for small values of the Brinkman number and the modified Peclet number. This condition is sufficiently satisfied for hydraulic oils, whereby...
Modeling multiphase flow using fluctuating hydrodynamics.
Chaudhri, Anuj; Bell, John B; Garcia, Alejandro L; Donev, Aleksandar
2014-09-01
Fluctuating hydrodynamics provides a model for fluids at mesoscopic scales where thermal fluctuations can have a significant impact on the behavior of the system. Here we investigate a model for fluctuating hydrodynamics of a single-component, multiphase flow in the neighborhood of the critical point. The system is modeled using a compressible flow formulation with a van der Waals equation of state, incorporating a Korteweg stress term to treat interfacial tension. We present a numerical algorithm for modeling this system based on an extension of algorithms developed for fluctuating hydrodynamics for ideal fluids. The scheme is validated by comparison of measured structure factors and capillary wave spectra with equilibrium theory. We also present several nonequilibrium examples to illustrate the capability of the algorithm to model multiphase fluid phenomena in a neighborhood of the critical point. These examples include a study of the impact of fluctuations on the spinodal decomposition following a rapid quench, as well as the piston effect in a cavity with supercooled walls. The conclusion in both cases is that thermal fluctuations affect the size and growth of the domains in off-critical quenches.
The Role of Thermal Conduction in Tearing Mode Theory
Connor, J W; Hastie, R J; Liu, Y Q
2014-01-01
The role of anisotropic thermal diffusivity on tearing mode stability is analysed in general toroidal geometry. A dispersion relation linking the growth rate to the tearing mode stability parameter, Delta, is derived. By using a resistive MHD code, modified to include such thermal transport, to calculate tearing mode growth rates, the dispersion relation is employed to determine Delta in situations with finite plasma pressure that are stabilised by favourable average curvature in a simple resistive MHD model. We also demonstrate that the same code can also be used to calculate the basis-functions [C J Ham, et al, Plasma Phys. Control. Fusion 54 (2012) 105014] needed to construct Delta.
Sadok, Walid; Naudin, Philippe; Boussuge, Benoit; Muller, Bertrand; Welcker, Claude; Tardieu, Francois
2007-02-01
We have analysed daily patterns of leaf elongation rate (LER) in large data sets with 318 genotypes placed in naturally fluctuating temperature and evaporative demand, and examined the effect of targeted alleles on these patterns. The method consisted, firstly, in expressing elongation rate per unit thermal time, so it became temperature independent; secondly, in a joint analysis of diurnal fluctuations of elongation rate and of micrometeorological conditions in several experiments, and finally, in a comparison of daily patterns between groups of genotypes possessing targeted alleles. (1) Conditions for using thermal time at a time step of 15 min were first tested successfully in 318 recombinant inbred lines (RILs) of three mapping populations. (2) An analysis of 1989 time courses revealed a robust daily pattern of LER per unit thermal time (LERth) over several experiments. LERth was constant during the night and was reproducible (for a given RIL) over up to 10 consecutive nights in different experiments. It declined rapidly during the early morning, closely following the daily pattern of transpiration rate. (3) Groups of RILs carrying alleles conferring a high response to temperature had markedly higher night-time plateau of LER than those with low responses. Groups of RILs with high response to evaporative demand had rapid decreases in elongation rate at the transition between night and day, while this decrease was slower in groups of RILs with low response. These results open the way for using kinetics of responses to environmental stimuli as a phenotyping tool in genetic analyses.
Fluctuation-enhanced electric conductivity in electrolyte solutions.
Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L
2017-10-10
We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.
Fin shape thermal optimization using Bejan's constuctal theory
Lorenzini, Giulio
2011-01-01
The book contains research results obtained by applying Bejan's Constructal Theory to the study and therefore the optimization of fins, focusing on T-shaped and Y-shaped ones. Heat transfer from finned surfaces is an example of combined heat transfer natural or forced convection on the external parts of the fin, and conducting along the fin. Fin's heat exchange is rather complex, because of variation of both temperature along the fin and convective heat transfer coefficient. Furthermore possible presence of more fins invested by the same fluid flow has to be considered.Classical fin theory tri
Mizugaki, Yoshinao; Urai, Yoshiaki; Shimada, Hiroshi
2017-07-01
A double-flux-quantum amplifier (DFQA) is a voltage multiplier of quantum accuracy, which we have employed at the final stage of a single-flux-quantum (SFQ) digital-to-analog converter (DAC). We recently found that experimental input-output (IO) characteristics of DFQAs were always slightly different from numerical results assuming ideally-periodic SFQ pulse trains. That is, experimental IO characteristics obtained using an over-biasing method were gradually deteriorated near their maximum operation voltages. Numerical simulation including the over-biasing method at a finite temperature suggested that the difference was likely to be attributed to thermally-fluctuated intervals of input SFQ pulses.
Determination of Thermal Conductivity of Silicate Matrix for Applications in Effective Media Theory
Fiala, Lukáš; Jerman, Miloš; Reiterman, Pavel; Černý, Robert
2018-02-01
Silicate materials have an irreplaceable role in the construction industry. They are mainly represented by cement-based- or lime-based materials, such as concrete, cement mortar, or lime plaster, and consist of three phases: the solid matrix and air and water present in the pores. Therefore, their effective thermal conductivity depends on thermal conductivities of the involved phases. Due to the time-consuming experimental determination of the effective thermal conductivity, its calculation by means of homogenization techniques presents a reasonable alternative. In the homogenization theory, both volumetric content and particular property of each phase need to be identified. For porous materials the most problematic part is to accurately identify thermal conductivity of the solid matrix. Due to the complex composition of silicate materials, the thermal conductivity of the matrix can be determined only approximately, based on the knowledge of thermal conductivities of its major compounds. In this paper, the thermal conductivity of silicate matrix is determined using the measurement of a sufficiently large set of experimental data. Cement pastes with different open porosities are prepared, dried, and their effective thermal conductivity is determined using a transient heat-pulse method. The thermal conductivity of the matrix is calculated by means of extrapolation of the effective thermal conductivity versus porosity functions to zero porosity. Its practical applicability is demonstrated by calculating the effective thermal conductivity of a three-phase silicate material and comparing it with experimental data.
Particle Production and Effective Thermalization in Inhomogeneous Mean Field Theory
Aarts, G.; Smit, J.
2000-01-01
As a toy model for dynamics in nonequilibrium quantum field theory we consider the abelian Higgs model in 1+1 dimensions with fermions. In the approximate dynamical equations, inhomogeneous classical (mean) Bose fields are coupled to quantized fermion fields, which are treated with a mode function
Fluctuating hydrodynamics for ionic liquids
Energy Technology Data Exchange (ETDEWEB)
Lazaridis, Konstantinos [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States); Wickham, Logan [Department of Computer Science, Washington State University, Richland, 99354 (United States); Voulgarakis, Nikolaos, E-mail: n.voulgarakis@wsu.edu [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States)
2017-04-25
We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau–Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids. - Highlights: • A new fluctuating hydrodynamics method for ionic liquids. • Description of ionic liquid morphology in bulk and near electrified surfaces. • Direct comparison with experimental measurements.
Massive basketball diagram for a thermal scalar field theory
Andersen, Jens O.; Braaten, Eric; Strickland, Michael
2000-08-01
The ``basketball diagram'' is a three-loop vacuum diagram for a scalar field theory that cannot be expressed in terms of one-loop diagrams. We calculate this diagram for a massive scalar field at nonzero temperature, reducing it to expressions involving three-dimensional integrals that can be easily evaluated numerically. We use this result to calculate the free energy for a massive scalar field with a φ4 interaction to three-loop order.
Thermal transport and quasi-normal modes in Gauss–Bonnet-axions theory
Directory of Open Access Journals (Sweden)
Xiao-Mei Kuang
2017-07-01
Full Text Available We obtain the black brane solution in arbitrary dimensional Gauss–Bonnet-axions (GBA gravity theory. And then the thermal conductivity of the boundary theory dual to this neutral black brane is explored. We find that the momentum dissipation suppresses the DC thermal conductivity while it is enhanced by larger GB parameter. The analytical and numerical results of DC thermal conductivity match very well. Also we study the effect of the momentum dissipation and the GB coupling on the AC thermal conductivity and fit the results by Drude-like behavior for low frequency. Finally, we analytical compute the quasi-normal modes (QNM frequency of the perturbative master field in large dimensions limit. Our analytical QNM frequencies agree well with the numerical results in large enough finite dimensions.
Witzel, K P
1980-04-01
In summer, the river Saar in the southwest of Germany exhibits distinct temperature fluctuations from 8 degrees C at the source to nearly 30 degrees C in the middle region. Temperature optima for bacterial plate counts and the uptake velocity of [U-C]glucose by the natural microbial communities of different regions ranged from 20 to 30 degrees C, which is significantly above the mean annual water temperature. A correlation between temperature optima and different seasons or habitats was not observed. Despite the relatively high temperature optima, the turnover time for glucose was shortest at temperatures around the mean annual water temperature, due to changes in the substrate affinity. At limiting substrate concentrations, the higher substrate affinity at lower temperatures may lead to a higher real activity at in situ temperatures, and a compensatory stabilization of uptake rates at fluctuating temperatures is possible.
Lipparini, Filippo; Barone, Vincenzo
2011-11-08
We present a combined fluctuating charges-polarizable continuum model approach to describe molecules in solution. Both static and dynamic approaches are discussed: analytical first and second derivatives are shown as well as an extended lagrangian for molecular dynamics simluations. In particular, we use the polarizable continuum model to provide nonperiodic boundary conditions for molecular dynamics simulations of aqueous solutions. The extended lagrangian method is extensively discussed, with specific reference to the fluctuating charge model, from a numerical point of view by means of several examples, and a rationalization of the behavior found is presented. Several prototypical applications are shown, especially regarding solvation of ions and polar molecules in water.
Thermal and viscous effects on sound waves: revised classical theory.
Davis, Anthony M J; Brenner, Howard
2012-11-01
In this paper the recently developed, bi-velocity model of fluid mechanics based on the principles of linear irreversible thermodynamics (LIT) is applied to sound propagation in gases taking account of first-order thermal and viscous dissipation effects. The results are compared and contrasted with the classical Navier-Stokes-Fourier results of Pierce for this same situation cited in his textbook. Comparisons are also made with the recent analyses of Dadzie and Reese, whose molecularly based sound propagation calculations furnish results virtually identical with the purely macroscopic LIT-based bi-velocity results below, as well as being well-supported by experimental data. Illustrative dissipative sound propagation examples involving application of the bi-velocity model to several elementary situations are also provided, showing the disjoint entropy mode and the additional, evanescent viscous mode.
Neutron moderation theory with thermal motion of the moderator nuclei
Rusov, V. D.; Tarasov, V. A.; Chernezhenko, S. A.; Kakaev, A. A.; Smolyar, V. P.
2017-09-01
In this paper we present the analytical expression for the neutron scattering law for an isotropic source of neutrons, obtained within the framework of the gas model with the temperature of the moderating medium as a parameter. The obtained scattering law is based on the solution of the general kinematic problem of elastic scattering of neutrons on nuclei in the L-system. Both the neutron and the nucleus possess arbitrary velocities in the L-system. For the new scattering law we obtain the flux densities and neutron moderation spectra as functions of temperature for the reactor fissile medium. The expressions for the moderating neutrons spectra allow reinterpreting the physical nature of the underlying processes in the thermal region.
Thermal and Field Enhanced Photoemission Comparison of Theory to Experiment
Lynn-Jensen, Kevin
2004-01-01
Photocathodes are a critical component of high-gain FELs and the analysis of their emission is complex. Relating their performance under laboratory conditions to conditions of an rf photoinjector is difficult. Useful models must account for cathode surface conditions and material properties, as well as drive laser parameters. We have developed a time-dependent model accounting for the effects of laser heating and thermal propagation on photoemission. It accounts for surface conditions (coating, field enhancement, reflectivity), laser parameters (duration, intensity, wavelength), and material characteristics (reflectivity, laser penetration depth, scattering rates) to predict current distribution and quantum efficiency. The applicatIon will focus on photoemission from metals and, in particular, dispenser photocathodes: the later introduces complications such as coverage non-uniformity and field enhancement. The performance of experimentally characterized photocathodes will be extrapolated to 0.1 - 1 nC bunch...
Neutron moderation theory with thermal motion of the moderator nuclei
Energy Technology Data Exchange (ETDEWEB)
Rusov, V.D.; Tarasov, V.A.; Chernezhenko, S.A.; Kakaev, A.A.; Smolyar, V.P. [Odessa National Polytechnic University, Department of Theoretical and Experimental Nuclear Physics, Odessa (Ukraine)
2017-09-15
In this paper we present the analytical expression for the neutron scattering law for an isotropic source of neutrons, obtained within the framework of the gas model with the temperature of the moderating medium as a parameter. The obtained scattering law is based on the solution of the general kinematic problem of elastic scattering of neutrons on nuclei in the L-system. Both the neutron and the nucleus possess arbitrary velocities in the L-system. For the new scattering law we obtain the flux densities and neutron moderation spectra as functions of temperature for the reactor fissile medium. The expressions for the moderating neutrons spectra allow reinterpreting the physical nature of the underlying processes in the thermal region. (orig.)
Dynamic nuclear polarisation by thermal mixing: quantum theory and macroscopic simulations.
Karabanov, Alexander; Kwiatkowski, Grzegorz; Perotto, Carlo U; Wiśniewski, Daniel; McMaster, Jonathan; Lesanovsky, Igor; Köckenberger, Walter
2016-11-02
A theory of dynamic nuclear polarisation (DNP) by thermal mixing is suggested based on purely quantum considerations. A minimal 6-level microscopic model is developed to test the theory and link it to the well-known thermodynamic model. Optimal conditions for the nuclear polarization enhancement and effects of inhomogeneous broadening of the electron resonance are discussed. Macroscopic simulations of nuclear polarization spectra displaying good agreement with experiments, involving BDPA and trityl free radicals, are presented.
Break-up dynamics of fluctuating liquid threads.
Petit, Julien; Rivière, David; Kellay, Hamid; Delville, Jean-Pierre
2012-11-06
The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from a faucet or a capillary, follows different rules and dynamic scaling laws depending on the importance of inertia, viscous stresses, or capillary forces. If now the thinning neck reaches dimensions comparable to the thermally excited interfacial fluctuations, as for nanojet break-up or the fragmentation of thermally annealed nanowires, these fluctuations should play a dominant role according to recent theory and observations. Using near-critical interfaces, we here fully characterize the universal dynamics of this thermal fluctuation-dominated regime and demonstrate that the cross-over from the classical two-fluid pinch-off scenario of a liquid thread to the fluctuation-dominated regime occurs at a well-defined neck radius proportional to the thermal length scale. Investigating satellite drop formation, we also show that at the level of the cross-over between these two regimes it is more probable to produce monodisperse droplets because fluctuation-dominated pinch-off may allow the unique situation where satellite drop formation can be inhibited. Nonetheless, the interplay between the evolution of the neck profiles from the classical to the fluctuation-dominated regime and the satellites' production remains to be clarified.
Uma, B; Eckmann, D M; Ayyaswamy, P S; Radhakrishnan, R
2012-01-01
A novel hybrid scheme based on Markovian fluctuating hydrodynamics of the fluid and a non-Markovian Langevin dynamics with the Ornstein-Uhlenbeck noise perturbing the translational and rotational equations of motion of the nanoparticle is employed to study the thermal motion of a nanoparticle in an incompressible Newtonian fluid medium. A direct numerical simulation adopting an arbitrary Lagrangian-Eulerian (ALE) based finite element method (FEM) is employed in simulating the thermal motion of a particle suspended in the fluid confined in a cylindrical vessel. The results for thermal equilibrium between the particle and the fluid are validated by comparing the numerically predicted temperature of the nanoparticle with that obtained from the equipartition theorem. The nature of the hydrodynamic interactions is verified by comparing the velocity autocorrelation function (VACF) and mean squared displacement (MSD) with well-known analytical results. For nanoparticle motion in an incompressible fluid, the fluctuating hydrodynamics approach resolves the hydrodynamics correctly but does not impose the correct equipartition of energy based on the nanoparticle mass because of the added mass of the displaced fluid. In contrast, the Langevin approach with an appropriate memory is able to show the correct equipartition of energy, but not the correct short- and long-time hydrodynamic correlations. Using our hybrid approach presented here, we show for the first time, that we can simultaneously satisfy the equipartition theorem and the (short- and long-time) hydrodynamic correlations. In effect, this results in a thermostat that also simultaneously preserves the true hydrodynamic correlations. The significance of this result is that our new algorithm provides a robust computational approach to explore nanoparticle motion in arbitrary geometries and flow fields, while simultaneously enabling us to study carrier adhesion mediated by biological reactions (receptor
Witzel, Karl-Paul
1980-01-01
In summer, the river Saar in the southwest of Germany exhibits distinct temperature fluctuations from 8°C at the source to nearly 30°C in the middle region. Temperature optima for bacterial plate counts and the uptake velocity of [U-14C]glucose by the natural microbial communities of different regions ranged from 20 to 30°C, which is significantly above the mean annual water temperature. A correlation between temperature optima and different seasons or habitats was not observed. Despite the r...
Thermodynamic fluctuations of electromagnetic field in slightly absorbing media
Directory of Open Access Journals (Sweden)
B.A.Veklenko
2004-01-01
Full Text Available A theory of thermodynamic fluctuations of electromagnetic field in slightly absorbing media is developed using the quantum electrodynamics - method of $Gamma$-operators - without phenomenology. The hypothesis offered by Yury L. Klimontovich is under consideration. The necessity of correct consideration of photon-photon correlation functions is shown. The results are compared with the ones obtained with the help of standard theory based upon fluctuation-dissipation theorem (FDT. The latter results are shown to have no field of application at least for the case of thermally excited media of the atoms described with two-level model.
Jin, Y. Q.; Kong, J. A.
1984-01-01
The strong fluctuation theory is applied to the study of electromagnetic wave scattering from a layer of random discrete scatterers. The singularity of the dyadic Green's function is taken into account in the calculation of the effective permittivity functions. The correlation functions for the random medium with different scatterer constituents and size distributions are derived. Applying the dyadic Green's function for a two-layer medium and using the bilocal and distorted Born approximations, the first and the second moments of the fields are then calculated. Both the backscattering and bistatic scattering coefficients are obtained, and the former is shown to match favorably with experimental data obtained from snow fields.
Einstein's coefficients and the wave-particle duality in the theory of thermal radiation
Prigara, Fedor V.
2005-01-01
It is shown that the concept of elementary resonator in the theory of thermal radiation implies the indivisible connection between particles (photons) and electromagnetic waves. This wave-particle duality covers both the Wien and Rayleigh-Jeans regions of spectrum.
Allen, Philip B.
2015-08-01
The quasiharmonic (QH) approximation uses harmonic vibrational frequencies ωQ ,H(V ) computed at volumes V near V0 where the Born-Oppenheimer (BO) energy Eel(V ) is minimum. When this is used in the harmonic free energy, QH approximation gives a good zeroth order theory of thermal expansion and first-order theory of bulk modulus, where nth-order means smaller than the leading term by ɛn, where ɛ =ℏ ωvib/Eel or kBT /Eel , and Eel is an electronic energy scale, typically 2 to 10 eV. Experiment often shows evidence for next-order corrections. When such corrections are needed, anharmonic interactions must be included. The most accessible measure of anharmonicity is the quasiparticle (QP) energy ωQ(V ,T ) seen experimentally by vibrational spectroscopy. However, this cannot just be inserted into the harmonic free energy FH. In this paper, a free energy is found that corrects the double-counting of anharmonic interactions that is made when F is approximated by FH( ωQ(V ,T ) ) . The term "QP thermodynamics" is used for this way of treating anharmonicity. It enables (n +1 ) -order corrections if QH theory is accurate to order n . This procedure is used to give corrections to the specific heat and volume thermal expansion. The QH formulas for isothermal (BT) and adiabatic (BS) bulk moduli are clarified, and the route to higher-order corrections is indicated.
Thermal isomerization of azobenzenes: on the performance of Eyring transition state theory
Rietze, Clemens; Titov, Evgenii; Lindner, Steven; Saalfrank, Peter
2017-08-01
The thermal Z\\to E (back-)isomerization of azobenzenes is a prototypical reaction occurring in molecular switches. It has been studied for decades, yet its kinetics is not fully understood. In this paper, quantum chemical calculations are performed to model the kinetics of an experimental benchmark system, where a modified azobenzene (AzoBiPyB) is embedded in a metal-organic framework (MOF). The molecule can be switched thermally from cis to trans, under solvent-free conditions. We critically test the validity of Eyring transition state theory for this reaction. As previously found for other azobenzenes (albeit in solution), good agreement between theory and experiment emerges for activation energies and activation free energies, already at a comparatively simple level of theory, B3LYP/6-31G* including dispersion corrections. However, theoretical Arrhenius prefactors and activation entropies are in qualitiative disagreement with experiment. Several factors are discussed that may have an influence on activation entropies, among them dynamical and geometric constraints (imposed by the MOF). For a simpler model—Z\\to E isomerization in azobenzene—a systematic test of quantum chemical methods from both density functional theory and wavefunction theory is carried out in the context of Eyring theory. Also, the effect of anharmonicities on activation entropies is discussed for this model system. Our work highlights capabilities and shortcomings of Eyring transition state theory and quantum chemical methods, when applied for the Z\\to E (back-)isomerization of azobenzenes under solvent-free conditions.
George, Janine; Deringer, Volker L; Wang, Ai; Müller, Paul; Englert, Ulli; Dronskowski, Richard
2016-12-21
Thermal properties of solid-state materials are a fundamental topic of study with important practical implications. For example, anisotropic displacement parameters (ADPs) are routinely used in physics, chemistry, and crystallography to quantify the thermal motion of atoms in crystals. ADPs are commonly derived from diffraction experiments, but recent developments have also enabled their first-principles prediction using periodic density-functional theory (DFT). Here, we combine experiments and dispersion-corrected DFT to quantify lattice thermal expansion and ADPs in crystalline α-sulfur (S8), a prototypical elemental solid that is controlled by the interplay of covalent and van der Waals interactions. We begin by reporting on single-crystal and powder X-ray diffraction measurements that provide new and improved reference data from 10 K up to room temperature. We then use several popular dispersion-corrected DFT methods to predict vibrational and thermal properties of α-sulfur, including the anisotropic lattice thermal expansion. Hereafter, ADPs are derived in the commonly used harmonic approximation (in the computed zero-Kelvin structure) and also in the quasi-harmonic approximation (QHA) which takes the predicted lattice thermal expansion into account. At the PPBE+D3(BJ) level, the QHA leads to excellent agreement with experiments. Finally, more general implications of this study for theory and experiment are discussed.
On the Use of GOES Thermal Data to Study Effects of Land Use on Diurnal Temperature Fluctuation.
Shih, S. F.; Chen, E.
1984-03-01
Geostationary Operational Environmental Satellite (GOES) infrared data were used to study the effect of land use on the diurnal surface temperature fluctuation. Five major land use types in southern Florida: the sandy soil agricultural area; the Everglades Agricultural Area (EAA); the conservation areas; the Natural Everglades Area (NEA); and Lake Okeechobee; were observed. The average daytime and nocturnal surface temperatures of sandy soil in agricultural areas was lower than that of organic soil in agricultural areas. The average temperature of organic soil in agricultural areas was lower than that of organic soil in conservation areas. The surface temperature in the wet marsh area was much lower than that in a large water-storage lake. A land use change in the EAA, and an increase in the water storage in Lake Okeechobee and the conservation areas could influence the microclimate.
Local Thermal Equilibrium in Quantum Field Theory on Flat and Curved Spacetimes
Solveen, Christoph
2010-01-01
The existence of local thermal equilibrium (LTE) states for quantum field theory in the sense of Buchholz, Ojima and Roos is discussed in a model-independent setting. It is shown that for spaces of finitely many independent thermal observables there always exist states which are in LTE in any compact region of Minkowski spacetime. Furthermore, LTE states in curved spacetime are discussed and it is observed that the original definition of LTE on curved backgrounds given by Buchholz and Schlemmer needs to be modified. Under an assumption related to certain unboundedness properties of the pointlike thermal observables, existence of states which are in LTE at a given point in curved spacetime is established. The assumption is discussed for the sets of thermal observables for the free scalar field considered by Schlemmer and Verch.
Local thermal equilibrium in quantum field theory on flat and curved spacetimes
Energy Technology Data Exchange (ETDEWEB)
Solveen, Christoph, E-mail: Christoph.Solveen@theorie.physik.uni-goettingen.d [Institut fuer Theoretische Physik, Universitaet Goettingen, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)
2010-12-07
The existence of local thermal equilibrium (LTE) states for quantum field theory in the sense of Buchholz, Ojima and Roos is discussed in a model-independent setting. It is shown that for spaces of finitely many independent thermal observables there always exist states which are in LTE in any compact region of Minkowski spacetime. Furthermore, LTE states in curved spacetime are discussed and it is observed that the original definition of LTE on curved backgrounds given by Buchholz and Schlemmer needs to be modified. Under an assumption related to certain unboundedness properties of the pointlike thermal observables, existence of states which are in LTE at a given point in curved spacetime is established. The assumption is discussed for the sets of thermal observables for the free scalar field considered by Schlemmer and Verch.
Dedkov, G. V.; Kyasov, A. A.
2009-01-01
It is shown that the limiting transition from the geometrical configuration "plate -plate" to configuration "small particle -plate" being frequently used in the theory of Lifshitz -Pitaevskii, is not continually true. On the other hand, the known solution to the problem in the last configuration can be used to verify the generalizations of the theory being worked out in the former configuration.
Thermal expansion of LaFeAsO1-xFx: evidence for high temperature fluctuations
Wang, L.; Köhler, U.; Leps, N.; Kondrat, A.; Nale, M.; Gasparini, A.; de Visser, A.; Behr, G.; Hess, C.; Klingeler, R.; Büchner, B.
2009-01-01
We present measurements of the thermal expansion coefficient α of polycrystalline LaFeAsO1−xFx (x≤0.1). The magnetic and structural transitions of the samples with x≤0.04 give rise to large anomalies in α(T) while the onset of superconductivity in the crystals with x≥0.05 is not resolved. Above the
Directory of Open Access Journals (Sweden)
Iñigo Antepara
2015-09-01
Full Text Available Thermal properties of mineral wool based materials appear to be of particular importance for their practical applications because the majority of them is used in the form of thermal insulation boards. Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly. Exposure to outside climate or any other environment containing moisture can negatively affect the thermal insulation properties of mineral wool. Nevertheless, the mineral wool materials due to their climatic loading and their environmental exposure contain moisture that can negatively affect their thermal insulation properties. Because the presence of water in mineral wool material is undesirable for the majority of applications, many products are provided with hydrophobic substances. Hydrophilic additives are seldom used in mineral wool products. However, this kind of materials has a good potential for application for instance in interior thermal insulation systems, masonry desalination, green roofs, etc. For these materials, certain moisture content must be estimated and thus their thermal properties will be different than for the dry state. On this account, moisture dependent thermal properties of hydrophilic mineral wool (HMW are studied in a wide range of moisture content using a pulse technique. The experimentally determined thermal conductivity data is analysed using several homogenization formulas based on the effective media theory. In terms of homogenization, a porous material is considered as a mixture of two or three phases. In case of dry state, material consists from solid and gaseous phase. When moistened, liquid phase is also present. Mineral wool consists of the solid phase represented by basalt fibers, the liquid phase by water and the gaseous phase by air. At first, the homogenization techniques are applied for the
An ab-initio coupled mode theory for near field radiative thermal transfer.
Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L
2014-12-01
We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer.
Whistler Cyclotron Electromagnetic Fluctuations in a Maxwellian and Tsallis-kappa-like Plasma
Vinas, A. F.; Moya, P. S.; Navarro, R.; Araneda, J. A.
2014-12-01
Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of non-thermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of whistler-cyclotron fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and non-thermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and non-thermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of non-thermal distributions due to the effective higher-temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and non-thermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in-situ particle measurements.
Thermal corrections to Rényi entropies for conformal field theories
Energy Technology Data Exchange (ETDEWEB)
Herzog, Christopher P.; Nian, Jun [C. N. Yang Institute for Theoretical Physics, Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)
2015-06-03
We compute thermal corrections to Rényi entropies of d dimensional conformal field theories on spheres. Consider the nth Rényi entropy for a cap of opening angle 2θ on S{sup d−1}. From a Boltzmann sum decomposition and the operator-state correspondence, the leading correction is related to a certain two-point correlation function of the operator (not equal to the identity) with smallest scaling dimension. More specifically, via a conformal map, the correction can be expressed in terms of the two-point function on a certain conical space with opening angle 2πn. In the case of free conformal field theories, this two-point function can be computed explicitly using the method of images. We perform the computation for the conformally coupled scalar. From the n→1 limit of our results, we extract the leading thermal correction to the entanglement entropy, reproducing results of arXiv:1407.1358.
Energy Technology Data Exchange (ETDEWEB)
Taheri, Said, E-mail: Said.taheri@edf.fr [EDF-LAB, IMSIA, 7 Boulevard Gaspard Monge, 91120 Palaiseau Cedex (France); Julan, Emricka [EDF-LAB, AMA, 7 Boulevard Gaspard Monge, 91120 Palaiseau Cedex (France); Tran, Xuan-Van [EDF Energy R& D UK Centre/School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL (United Kingdom); Robert, Nicolas [EDF-DPN, UNIE, Strategic Center, Saint Denis (France)
2017-01-15
Highlights: • For crack growth analysis, weld residual stress field must be considered through its SIF in presence of a crack. • Presence of cracks of same depth proves their arrest, where equal depth is because mean stress acts only on crack opening. • Not considering amplitudes under a fatigue crack growth threshold (FCGT) does not compensate the lack of FGCT in Paris law. • Propagation rates are close for axisymmetric and circumferential semi-elliptical cracks. - Abstract: High cycle thermal crazing has been observed in some residual heat removal (RHR) systems made of 304 stainless steel in PWR nuclear plants. This paper deals with two types of analyses including logical argumentation and simulation. Crack arrest in networks is demonstrated due to the presence of two cracks of the same depth in the network. This identical depth may be proved assuming that mean stress acts only on crack opening and that cracks are fully open during the load cycle before arrest. Weld residual stresses (WRS) are obtained by an axisymmetric simulation of welding on a tube with a chamfer. Axisymmetric and 3D parametric studies of crack growth on: representative sequences for variable amplitude thermal loading, fatigue crack growth threshold (FCGT), permanent mean stress, cyclic counting methods and WRS, are performed with Code-Aster software using XFEM methodology. The following results are obtained on crack depth versus time: the effect of WRS on crack growth cannot be determined by the initial WRS field in absence of crack, but by the associated stress intensity factor. Moreover the relation between crack arrest depth and WRS is analyzed. In the absence of FCGT Paris’s law may give a significant over-estimation of crack depth even if amplitudes of loading smaller than FCGT have not been considered. Appropriate depth versus time may be obtained using different values of FCGT, but axisymmetric simulations do not really show a possibility of arrest for shallow cracks in
A mixture theory model for a particulate suspension flow in a thermal non-equilibrium context
Energy Technology Data Exchange (ETDEWEB)
Martins-Costa, M.L. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Lab. de Mecanica Teorica e Aplicada; Gama, R.M. Saldanha da [Laboratorio Nacional de Computacao Cientifica (LNCC), Rio de Janeiro, RJ (Brazil)
1998-07-01
The present work proposes a local model for a particulate suspension flow employing the continuum theory of mixture - specially developed to deal with multiphase phenomena. The flow of a Newtonian fluid with small solid particles in suspension - in which thermal non-equilibrium is allowed - is described as a mixture of solid and fluid constituents coexisting superposed. Thermo-dynamically consistent constitutive hypotheses are derived in order an adequate model for suspensions. (author)
A Model of Thermal Conductivity for Planetary Soils: 1. Theory for Unconsolidated Soils
Piqueux, S.; Christensen, P. R.
2009-01-01
We present a model of heat conduction for mono-sized spherical particulate media under stagnant gases based on the kinetic theory of gases, numerical modeling of Fourier s law of heat conduction, theoretical constraints on the gas thermal conductivity at various Knudsen regimes, and laboratory measurements. Incorporating the effect of the temperature allows for the derivation of the pore-filling gas conductivity and bulk thermal conductivity of samples using additional parameters (pressure, gas composition, grain size, and porosity). The radiative and solid-to-solid conductivities are also accounted for. Our thermal model reproduces the well-established bulk thermal conductivity dependency of a sample with the grain size and pressure and also confirms laboratory measurements finding that higher porosities generally lead to lower conductivities. It predicts the existence of the plateau conductivity at high pressure, where the bulk conductivity does not depend on the grain size. The good agreement between the model predictions and published laboratory measurements under a variety of pressures, temperatures, gas compositions, and grain sizes provides additional confidence in our results. On Venus, Earth, and Titan, the pressure and temperature combinations are too high to observe a soil thermal conductivity dependency on the grain size, but each planet has a unique thermal inertia due to their different surface temperatures. On Mars, the temperature and pressure combination is ideal to observe the soil thermal conductivity dependency on the average grain size. Thermal conductivity models that do not take the temperature and the pore-filling gas composition into account may yield significant errors.
Low-frequency fluctuations in plasma magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Cable, S.; Tajima, T.
1992-02-01
It is shown that even a non-magnetized plasma with temperature T sustains zero-frequency magnetic fluctuations in thermal equilibrium. Fluctuations in electric and magnetic fields, as well as in densities, are computed. Four cases are studied: a cold, gaseous, isotropic, non-magnetized plasma; a cold, gaseous plasma in a uniform magnetic field; a warm, gaseous plasma described by kinetic theory; and a degenerate electron plasma. For the simple gaseous plasma, the fluctuation strength of the magnetic field as a function of frequency and wavenumber is calculated with the aid of the fluctuation-dissipation theorem. This calculation is done for both collisional and collisionless plasmas. The magnetic field fluctuation spectrum of each plasma has a large zero-frequency peak. The peak is a Dirac {delta}-function in the collisionless plasma; it is broadened into a Lorentzian curve in the collisional plasma. The plasma causes a low frequency cutoff in the typical black-body radiation spectrum, and the energy under the discovered peak approximates the energy lost in this cutoff. When the imposed magnetic field is weak, the magnetic field were vector fluctuation spectra of the two lowest modes are independent of the strength of the imposed field. Further, these modes contain finite energy even when the imposed field is zero. It is the energy of these modes which forms the non-magnetized zero-frequency peak of the isotropic plasma. In deriving these results, a simple relationship between the dispersion relation and the fluctuation power spectrum of electromagnetic waves if found. The warm plasma is shown, by kinetic theory, to exhibit a zero-frequency peak in its magnetic field fluctuation spectrum as well. For the degenerate plasma, we find that electric field fluctuations and number density fluctuations vanish at zero frequency; however, the magnetic field power spectrum diverges at zero frequency.
Fluctuation Theorem for Many-Body Pure Quantum States
Iyoda, Eiki; Kaneko, Kazuya; Sagawa, Takahiro
2017-09-01
We prove the second law of thermodynamics and the nonequilibrium fluctuation theorem for pure quantum states. The entire system obeys reversible unitary dynamics, where the initial state of the heat bath is not the canonical distribution but is a single energy eigenstate that satisfies the eigenstate-thermalization hypothesis. Our result is mathematically rigorous and based on the Lieb-Robinson bound, which gives the upper bound of the velocity of information propagation in many-body quantum systems. The entanglement entropy of a subsystem is shown connected to thermodynamic heat, highlighting the foundation of the information-thermodynamics link. We confirmed our theory by numerical simulation of hard-core bosons, and observed dynamical crossover from thermal fluctuations to bare quantum fluctuations. Our result reveals a universal scenario that the second law emerges from quantum mechanics, and can be experimentally tested by artificial isolated quantum systems such as ultracold atoms.
Fluctuation Theorem for Many-Body Pure Quantum States.
Iyoda, Eiki; Kaneko, Kazuya; Sagawa, Takahiro
2017-09-08
We prove the second law of thermodynamics and the nonequilibrium fluctuation theorem for pure quantum states. The entire system obeys reversible unitary dynamics, where the initial state of the heat bath is not the canonical distribution but is a single energy eigenstate that satisfies the eigenstate-thermalization hypothesis. Our result is mathematically rigorous and based on the Lieb-Robinson bound, which gives the upper bound of the velocity of information propagation in many-body quantum systems. The entanglement entropy of a subsystem is shown connected to thermodynamic heat, highlighting the foundation of the information-thermodynamics link. We confirmed our theory by numerical simulation of hard-core bosons, and observed dynamical crossover from thermal fluctuations to bare quantum fluctuations. Our result reveals a universal scenario that the second law emerges from quantum mechanics, and can be experimentally tested by artificial isolated quantum systems such as ultracold atoms.
Charge-Induced Fluctuation Forces in Graphitic Nanostructures
Directory of Open Access Journals (Sweden)
D. Drosdoff
2016-01-01
Full Text Available Charge fluctuations in nanocircuits with capacitor components are shown to give rise to a novel type of long-ranged interaction, which coexist with the regular Casimir–van der Waals force. The developed theory distinguishes between thermal and quantum mechanical effects, and it is applied to capacitors involving graphene nanostructures. The charge fluctuations mechanism is captured via the capacitance of the system with geometrical and quantum mechanical components. The dependence on the distance separation, temperature, size, and response properties of the system shows that this type of force can have a comparable and even dominant effect to the Casimir interaction. Our results strongly indicate that fluctuation-induced interactions due to various thermodynamic quantities can have important thermal and quantum mechanical contributions at the microscale and the nanoscale.
Cheaito, Ramez; Gaskins, John T.; Caplan, Matthew E.; Donovan, Brian F.; Foley, Brian M.; Giri, Ashutosh; Duda, John C.; Szwejkowski, Chester J.; Constantin, Costel; Brown-Shaklee, Harlan J.; Ihlefeld, Jon F.; Hopkins, Patrick E.
2015-01-01
The advances in phonon spectroscopy in homogeneous solids have unveiled extremely useful physics regarding the contribution of phonon energies and mean-free paths to the thermal transport in solids. However, as material systems decrease to length scales less than the phonon mean-free paths, thermal transport can become much more impacted by scattering and transmission across interfaces between two materials than the intrinsic relaxation in the homogeneous solid. To elucidate the fundamental interactions driving this thermally limiting interfacial phonon scattering process, we analytically derive and experimentally measure a thermal boundary conductance accumulation function. We develop a semiclassical theory to calculate the thermal boundary conductance accumulation function across interfaces using the diffuse mismatch model, and validate this derivation by measuring the interface conductance between eight different metals on native oxide/silicon substrates and four different metals on sapphire substrates. Measurements were performed at room temperature using time-domain thermoreflectance and represent the first-reported values for interface conductance across several metal/native oxide/silicon and metal/sapphire interfaces. The various metal films provide a variable bandwidth of phonons incident on the metal/substrate interface. This method of varying phonons' cutoff frequency in the film while keeping the same substrate allows us to mimic the accumulation of thermal boundary conductance and thus provides a direct method to experimentally validate our theory. We show that the accumulation function can be written as the product of a weighted average of the interfacial phonon transmission function and the accumulation of the temperature derivative of the phonon flux incident on the interface; this provides the framework to extract an average, spectrally dependent phonon transmissivity from a series of thermal boundary conductance measurements. Our approach provides
Zhao, Yu-Chen; Liu, Jiang-Fan; Song, Zhong-Guo; Xi, Xiao-Li
2014-12-01
Multi-needle zinc oxide whisker (M-ZnOw) includes tetrapod-needle ZnOw (T-ZnOw), flower-shaped ZnOw, and other similar ZnOw architectures. The unique three-dimensional (3D) and multi-needle-shaped structures give the special performance of M-ZnOw, but make it difficult to calculate the effective electromagnetic parameters of M-ZnOw composites. In this paper, based on the equivalent spherical particle and the strong fluctuation theory, three different closed-form expressions are presented to calculate the effective electromagnetic parameters of M-ZnOw composites. To start with, because of the macroscopic isotropic nature of M-ZnOw composites and lossy properties of M-ZnOw itself, an equivalent spherical particle is introduced in the scheme to simplify the unique microscopic structures of M-ZnOw, and the possible limitations of the presented equivalent spherical particle are discussed qualitatively. In addition, different closed-form expressions to calculate the effective electromagnetic parameter are obtained by means of representing the physical situations of conductive network as different correlation functions in the strong fluctuation theory. Finally, the effective permeability of a T-ZnOw/Fe - paraffin composite is calculated by these three expressions in 2-18 GHz frequency range. Very good agreement between the calculated and experimental results on one hand verifies the rationality of presented expressions, and on the other hand indicates that the correlation function plays an important role in improving the performance of the presented expression.
Effective Thermal Conductivity of Open Cell Polyurethane Foam Based on the Fractal Theory
Directory of Open Access Journals (Sweden)
Kan Ankang
2013-01-01
Full Text Available Based on the fractal theory, the geometric structure inside an open cell polyurethane foam, which is widely used as adiabatic material, is illustrated. A simplified cell fractal model is created. In the model, the method of calculating the equivalent thermal conductivity of the porous foam is described and the fractal dimension is calculated. The mathematical formulas for the fractal equivalent thermal conductivity combined with gas and solid phase, for heat radiation equivalent thermal conductivity and for the total thermal conductivity, are deduced. However, the total effective heat flux is the summation of the heat conduction by the solid phase and the gas in pores, the radiation, and the convection between gas and solid phase. Fractal mathematical equation of effective thermal conductivity is derived with fractal dimension and vacancy porosity in the cell body. The calculated results have good agreement with the experimental data, and the difference is less than 5%. The main influencing factors are summarized. The research work is useful for the enhancement of adiabatic performance of foam materials and development of new materials.
Studies of Fluctuation Processes in Nuclear Collisions
Energy Technology Data Exchange (ETDEWEB)
Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics
2016-04-14
The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and
Biomass ignition in mills and storages – is it explained by conventional thermal ignition theory?
DEFF Research Database (Denmark)
Schwarzer, Lars; Jensen, Peter Arendt; Glarborg, Peter
Self-ignition temperatures determined in the framework of conventional thermal ignition theory does not explain why biomass is much more susceptible to spontaneous ignition in power plant mills or storages. Examining the onset of reactions at low temperatures may provide a better understanding...... of the process, which can then be incorporated into refined models of self-ignition for biomass and other organic solids. In the present study, the slow, transient heating of several lignocellulosic biomasses and a bituminous coal from ambient temperature to around 300° C were investigated in a lab scale tube......, suggesting that a heterogeneous oxidation is the dominating mechanism in self-ignition. It could also be shown that both mechanisms compete for reactive material. While oxidation was exothermic, pyrolysis was largely thermally neutral in these experiments. Reaction behavior was seen to depend highly...
Fluctuation conductivity in cuprate superconductors
Indian Academy of Sciences (India)
superconducting layers in each unit cell is also not adequate. We suggest the fluctuation conductivity to be reduced due to the reduction in the density of states (DOS) of the quasiparticles which results due to the formation of Cooper pairs at the onset of the fluctuations. The data agrees with the theory proposed by Dorin et al ...
Effective field theories for heavy Majorana neutrinos in a thermal bath
Energy Technology Data Exchange (ETDEWEB)
Biondini, Simone
2016-05-06
In the leptogenesis framework Majorana neutrinos are at the origin of the baryon asymmetry in the universe. We develop an effective field theory for non-relativistic Majorana fermions and we apply it to the case of a heavy Majorana neutrino decaying in a hot plasma of Standard Model particles, whose temperature is much smaller than the mass of the Majorana neutrino but still much larger than the electroweak scale. Moreover we compute systematically thermal corrections to the CP asymmetries in the Majorana neutrino decays.
Data collection method for mobile sensor networks based on the theory of thermal fields.
Macuha, Martin; Tariq, Muhammad; Sato, Takuro
2011-01-01
Many sensor applications are aimed for mobile objects, where conventional routing approaches of data delivery might fail. Such applications are habitat monitoring, human probes or vehicular sensing systems. This paper targets such applications and proposes lightweight proactive distributed data collection scheme for Mobile Sensor Networks (MSN) based on the theory of thermal fields. By proper mapping, we create distribution function which allows considering characteristics of a sensor node. We show the functionality of our proposed forwarding method when adapted to the energy of sensor node. We also propose enhancement in order to maximize lifetime of the sensor nodes. We thoroughly evaluate proposed solution and discuss the tradeoffs.
Mirigian, Stephen; Schweizer, Kenneth S
2014-05-21
Building on the elastically collective nonlinear Langevin equation theory developed for hard spheres in Paper I, we propose and implement a quasi-universal theory for the alpha relaxation of thermal liquids based on mapping them to an effective hard sphere fluid via the dimensionless compressibility. The result is a zero adjustable parameter theory that can quantitatively address in a unified manner the alpha relaxation time over 14 or more decades. The theory has no singularities above zero Kelvin, and relaxation in the equilibrium low temperature limit is predicted to be of a roughly Arrhenius form. The two-barrier (local cage and long range collective elastic) description results in a rich dynamic behavior including apparent Arrhenius, narrow crossover, and deeply supercooled regimes, and multiple characteristic or crossover times and temperatures of clear physical meaning. Application of the theory to nonpolar molecules, alcohols, rare gases, and liquids metals is carried out. Overall, the agreement with experiment is quite good for the temperature dependence of the alpha time, plateau shear modulus, and Boson-like peak frequency for van der Waals liquids, though less so for hydrogen-bonding molecules. The theory predicts multiple growing length scales upon cooling, which reflect distinct aspects of the coupled local hopping and cooperative elastic physics. Calculations of the growth with cooling of an activation volume, which is strongly correlated with a measure of dynamic cooperativity, agree quantitatively with experiment. Comparisons with elastic, entropy crisis, dynamic facilitation, and other approaches are performed, and a fundamental basis for empirically extracted crossover temperatures is established. The present work sets the stage for addressing distinctive glassy phenomena in polymer melts, and diverse liquids under strong confinement.
Fluctuations in solidification
Energy Technology Data Exchange (ETDEWEB)
Karma, A. (Physics Department, Northeastern University, Boston, Massachusetts 02115 (United States))
1993-11-01
We present an analytical treatment of (i) the incorporation of thermal noise in the basic continuum models of solidification, (ii) fluctuations about nonequilibrium steady states, and (iii) the amplification of noise near the onset of morphological instability. In (i), we find that the proper Langevin formalism, consistent with both bulk and interfacial equilibrium fluctuations, consists of the usual bulk forces and an extra stochastic force on the interface associated with its local kinetics. At sufficiently large solidification rate, this force affects interfacial fluctuations on scales where they are macroscopically amplified and, thus, becomes relevant. An estimate of this rate is given. In (ii), we extend the Langevin formalism outside of equilibrium to characterize the fluctuations of a stationary and a directionally solidified planar interface in a temperature gradient. Finally, in (iii), we derive an analytic expression for the linear growth of the mean-square amplitude of fluctuations slightly above the onset of morphological instability. The amplitude of the noise is found to be determined by the small parameter [ital k][sub [ital B]T[ital E]d0][sup [ital c]l][sub [ital T
Nonlinear effects of the thermal stabilization theory of applied superconducting materials
Romanovskii, V. R.
2017-11-01
The stability of dissipative states of a Bi2Sr2CaCu2O8 applied superconducting composite cooled by liquid helium or hydrogen with continuously increasing current-voltage characteristics described by a power equation has been studied. It has been shown that, under intensive cooling conditions, special conditions of thermal stabilization can exist for applied superconducting materials (technical superconductors) if the nonlinear temperature dependences of critical current density and specific resistance of the stabilizing matrix are taken into account. First, the minimum currents of existence and propagation of a normal zone can be absent. Second, the intensive cooling of a technical superconductor substantially increases the range of stable currents in the diapason of supercritical currents. Third, during the irreversible propagation of the thermal instability, the temperature of a technical superconductor can increase under conditions close to adiabatic, despite cooling by liquid coolant. These effects should be taken into account upon determining the conditions for overheating a technical superconductor. The numerical experiments have been compared with the results that follow from the thermal stabilization theory of combined superconductors, which assumes a linear temperature dependence of critical current density of a superconductor and a step-wise transition from the superconducting to normal state.
Dewar, R
2003-01-01
Jaynes' information theory formalism of statistical mechanics is applied to the stationary states of open, non-equilibrium systems. First, it is shown that the probability distribution p subGAMMA of the underlying microscopic phase space trajectories GAMMA over a time interval of length tau satisfies p subGAMMA propor to exp(tau sigma subGAMMA/2k sub B) where sigma subGAMMA is the time-averaged rate of entropy production of GAMMA. Three consequences of this result are then derived: (1) the fluctuation theorem, which describes the exponentially declining probability of deviations from the second law of thermodynamics as tau -> infinity; (2) the selection principle of maximum entropy production for non-equilibrium stationary states, empirical support for which has been found in studies of phenomena as diverse as the Earth's climate and crystal growth morphology; and (3) the emergence of self-organized criticality for flux-driven systems in the slowly-driven limit. The explanation of these results on general inf...
Micha, Raphael; Micha, Raphael; Tkachev, Igor I.
2004-01-01
We study, analytically and with lattice simulations, the decay of coherent field oscillations and the subsequent thermalization of the resulting stochastic classical wave-field. The problem of reheating of the Universe after inflation constitutes our prime motivation and application of the results. We identify three different stages of these processes. During the initial stage of ``parametric resonance'', only a small fraction of the initial inflaton energy is transferred to fluctuations in the physically relevant case of sufficiently large couplings. A major fraction is transfered in the prompt regime of driven turbulence. The subsequent long stage of thermalization classifies as free turbulence. During the turbulent stages, the evolution of particle distribution functions is self-similar. We show that wave kinetic theory successfully describes the late stages of our lattice calculation. Our analytical results are general and give estimates of reheating time and temperature in terms of coupling constants and...
Actin filaments growing against a barrier with fluctuating shape.
Sadhu, Raj Kumar; Chatterjee, Sakuntala
2016-06-01
We study force generation by a set of parallel actin filaments growing against a nonrigid obstacle, in the presence of an external load. The filaments polymerize by either moving the whole obstacle, with a large energy cost, or by causing local distortion in its shape which costs much less energy. The nonrigid obstacle also has local thermal fluctuations due to which its shape can change with time and we describe this using fluctuations in the height profile of a one-dimensional interface with Kardar-Parisi-Zhang dynamics. We find the shape fluctuations of the barrier strongly affect the force generation mechanism. The qualitative nature of the force-velocity curve is crucially determined by the relative time scale of filament and barrier dynamics. The height profile of the barrier also shows interesting variation with the external load. Our analytical calculations within mean-field theory show reasonable agreement with our simulation results.
Transition between two regimes describing internal fluctuation of DNA in a nanochannel.
Directory of Open Access Journals (Sweden)
Tianxiang Su
Full Text Available We measure the thermal fluctuation of the internal segments of a piece of DNA confined in a nanochannel about 50-100 nm wide. This local thermodynamic property is key to accurate measurement of distances in genomic analysis. For DNA in ~100 nm channels, we observe a critical length scale ~10 m for the mean extension of internal segments, below which the de Gennes' theory describes the fluctuations with no fitting parameters, and above which the fluctuation data falls into Odijk's deflection theory regime. By analyzing the probability distributions of the extensions of the internal segments, we infer that folded structures of length 150-250 nm, separated by ~10 m exist in the confined DNA during the transition between the two regimes. For ~50 nm channels we find that the fluctuation is significantly reduced since the Odijk regime appears earlier. This is critical for genomic analysis. We further propose a more detailed theory based on small fluctuations and incorporating the effects of confinement to explicitly calculate the statistical properties of the internal fluctuations. Our theory is applicable to polymers with heterogeneous mechanical properties confined in non-uniform channels. We show that existing theories for the end-to-end extension/fluctuation of polymers can be used to study the internal fluctuations only when the contour length of the polymer is many times larger than its persistence length. Finally, our results suggest that introducing nicks in the DNA will not change its fluctuation behavior when the nick density is below 1 nick per kbp DNA.
Simple theory of low-temperature thermal conductivity in single- and double-walled carbon nanotubes
Chalin, D. V.; Avramenko, M. V.; Rochal, S. B.
2017-10-01
Low-temperature phonon thermal conductance (PTC) of any 1D system increases proportionally to the temperature. However, here we show that in single- and double-walled carbon nanotubes (CNTs), starting from 3-6 K, the PTC increases faster than the linear function, since the low-frequency modes of dispersion curves, which do not tend to zero together with the wave vector, are excited. To develop the PTC theory, we combine the Landauer's ballistic approach with the simple continuous model proposed for the calculation of the low-frequency phonon spectra of both free nanotubes and those interacting with an environment. The approach obtained is valid not only for commensurate double-walled CNTs, but also for incommensurate ones. The temperature-dependent relation between the PTC of double-walled CNT and those of its constituent SWNTs is obtained and discussed. The low-temperature heat transfer in bulk materials originated from CNTs is also considered and the upper limit of thermal conductivity of such materials is determined. We argue that the ideal material consisting of CNTs can challenge diamond only when the mean length of its defect-free nanotubes reaches at least one hundred of micrometers.
Sokolowsky, Kathleen P; Bailey, Heather E; Hoffman, David J; Andersen, Hans C; Fayer, Michael D
2016-07-21
Two-dimensional infrared (2D IR) data are presented for a vibrational probe in three nematogens: 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-octylbiphenyl, and 4-(trans-4-amylcyclohexyl)-benzonitrile. The spectral diffusion time constants in all three liquids in the isotropic phase are proportional to [T*/(T - T*)](1/2), where T* is 0.5-1 K below the isotropic-nematic phase transition temperature (TNI). Rescaling to a reduced temperature shows that the decays of the frequency-frequency correlation function (FFCF) for all three nematogens fall on the same curve, suggesting a universal dynamic behavior of nematogens above TNI. Spectral diffusion is complete before significant orientational relaxation in the liquid, as measured by optically heterodyne detected-optical Kerr effect (OHD-OKE) spectroscopy, and before any significant orientational randomization of the probe measured by polarization selective IR pump-probe experiments. To interpret the OHD-OKE and FFCF data, we constructed a mode coupling theory (MCT) schematic model for the relationships among three correlation functions: ϕ1, a correlator for large wave vector density fluctuations; ϕ2, the orientational correlation function whose time derivative is the observable in the OHD-OKE experiment; and ϕ3, the FFCF for the 2D IR experiment. The equations for ϕ1 and ϕ2 match those in the previous MCT schematic model for nematogens, and ϕ3 is coupled to the first two correlators in a straightforward manner. Resulting models fit the data very well. Across liquid crystals, the temperature dependences of the coupling constants show consistent, nonmonotonic behavior. A remarkable change in coupling occurs at ∼5 K above TNI, precisely where the rate of spectral diffusion in 5CB was observed to deviate from that of a similar nonmesogenic liquid.
Fluctuations in Ultra-Relativistic Heavy Ion Collisions
Mazeliauskas, Aleksas
leading order effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations. For the short evolution we can use a linear response theory to construct the pre-equilibrium Green functions. Then the energy-momentum tensor at a time when hydrodynamics becomes applicable can be expressed as a linear convolution of response functions with the initial perturbations. We propose combining effective kinetic theory with weak coupling initial state models, such as IP-Glasma, to model the complete pre-thermal evolution from saturated nuclei to hydrodynamics in a weak coupling framework. Last, in Chapter 5 we consider out-of-equilibrium hydrodynamic fluctuations in the expanding QGP. We develop a set of kinetic equations for a correlator of thermal fluctuations which are equivalent to nonlinear hydrodynamics with noise. We first show that the kinetic response precisely reproduces the one-loop renormalization of the shear viscosity for a static fluid. We then use the hydro-kinetic equations to analyze thermal fluctuations for a Bjorken expansion. The steady state solution to the kinetic equations determine the coefficient of the first fractional power of the gradient expansion (infinity 1/(tau T)3/2), which was computed here for the first time. The formalism of hydro-kinetic equations can be applied to more general background flows and coupled to existing viscous hydrodynamic codes to incorporate the physics of hydrodynamic fluctuations.
Deringer, Volker L; George, Janine; Dronskowski, Richard; Englert, Ulli
2017-05-16
Molecular compounds, organic and inorganic, crystallize in diverse and complex structures. They continue to inspire synthetic efforts and "crystal engineering", with implications ranging from fundamental questions to pharmaceutical research. The structural complexity of molecular solids is linked with diverse intermolecular interactions: hydrogen bonding with all its facets, halogen bonding, and other secondary bonding mechanisms of recent interest (and debate). Today, high-resolution diffraction experiments allow unprecedented insight into the structures of molecular crystals. Despite their usefulness, however, these experiments also face problems: hydrogen atoms are challenging to locate, and thermal effects may complicate matters. Moreover, even if the structure of a crystal is precisely known, this does not yet reveal the nature and strength of the intermolecular forces that hold it together. In this Account, we show that periodic plane-wave-based density functional theory (DFT) can be a useful, and sometimes unexpected, complement to molecular crystallography. Initially developed in the solid-state physics communities to treat inorganic solids, periodic DFT can be applied to molecular crystals just as well: theoretical structural optimizations "help out" by accurately localizing the elusive hydrogen atoms, reaching neutron-diffraction quality with much less expensive measurement equipment. In addition, phonon computations, again developed by physicists, can quantify the thermal motion of atoms and thus predict anisotropic displacement parameters and ORTEP ellipsoids "from scratch". But the synergy between experiment and theory goes much further than that. Once a structure has been accurately determined, computations give new and detailed insights into the aforementioned intermolecular interactions. For example, it has been debated whether short hydrogen bonds in solids have covalent character, and we have added a new twist to this discussion using an orbital
Wang En Ke
2002-01-01
The nonperturbative result of the shear viscosity in thermal phi sup 4 theory is given by solving the Bethe-Salpeter (B-S) integral equation in the closed time formalism in real time. By introducing a two-legs-truncated Green function it is shown that the B-S equation is decoupled in the basis of the Keldysh field
George, Janine; Deringer, Volker L.; Wang, Ai; Müller, Paul; Englert, Ulli; Dronskowski, Richard
2016-12-01
Thermal properties of solid-state materials are a fundamental topic of study with important practical implications. For example, anisotropic displacement parameters (ADPs) are routinely used in physics, chemistry, and crystallography to quantify the thermal motion of atoms in crystals. ADPs are commonly derived from diffraction experiments, but recent developments have also enabled their first-principles prediction using periodic density-functional theory (DFT). Here, we combine experiments and dispersion-corrected DFT to quantify lattice thermal expansion and ADPs in crystalline α-sulfur (S8), a prototypical elemental solid that is controlled by the interplay of covalent and van der Waals interactions. We begin by reporting on single-crystal and powder X-ray diffraction measurements that provide new and improved reference data from 10 K up to room temperature. We then use several popular dispersion-corrected DFT methods to predict vibrational and thermal properties of α-sulfur, including the anisotropic lattice thermal expansion. Hereafter, ADPs are derived in the commonly used harmonic approximation (in the computed zero-Kelvin structure) and also in the quasi-harmonic approximation (QHA) which takes the predicted lattice thermal expansion into account. At the PPBE+D3(BJ) level, the QHA leads to excellent agreement with experiments. Finally, more general implications of this study for theory and experiment are discussed.
Gambling with Superconducting Fluctuations
Foltyn, Marek; Zgirski, Maciej
2015-08-01
Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.
Fluctuating Selection in the Moran.
Dean, Antony M; Lehman, Clarence; Yi, Xiao
2017-03-01
Contrary to classical population genetics theory, experiments demonstrate that fluctuating selection can protect a haploid polymorphism in the absence of frequency dependent effects on fitness. Using forward simulations with the Moran model, we confirm our analytical results showing that a fluctuating selection regime, with a mean selection coefficient of zero, promotes polymorphism. We find that increases in heterozygosity over neutral expectations are especially pronounced when fluctuations are rapid, mutation is weak, the population size is large, and the variance in selection is big. Lowering the frequency of fluctuations makes selection more directional, and so heterozygosity declines. We also show that fluctuating selection raises dn /ds ratios for polymorphism, not only by sweeping selected alleles into the population, but also by purging the neutral variants of selected alleles as they undergo repeated bottlenecks. Our analysis shows that randomly fluctuating selection increases the rate of evolution by increasing the probability of fixation. The impact is especially noticeable when the selection is strong and mutation is weak. Simulations show the increase in the rate of evolution declines as the rate of new mutations entering the population increases, an effect attributable to clonal interference. Intriguingly, fluctuating selection increases the dn /ds ratios for divergence more than for polymorphism, a pattern commonly seen in comparative genomics. Our model, which extends the classical neutral model of molecular evolution by incorporating random fluctuations in selection, accommodates a wide variety of observations, both neutral and selected, with economy. Copyright © 2017 by the Genetics Society of America.
Soudzilovskaia, N.A.; Cornelissen, J.H.C.; van Bodegom, P.M.
2013-01-01
Bryophytes cover large territories in cold biomes, where they control soil temperature regime, and therefore permafrost, carbon and nutrient dynamics. The mechanisms of this control remain unclear. We quantified the dependence of soil temperature fluctuations under bryophyte mats on the interplay of
Kinetic theory of gases, magneto-fluid dynamics and their application. Interim 1 Dec 81-30 Nov 82
Energy Technology Data Exchange (ETDEWEB)
Grad, H.
1983-01-01
This paper describes research results and cites progress resulting from work performed during this period of the grant. The areas covered in this report are (1) mathematical theory of turbulent fluctuations of a plasma near thermal equilibrium, (2) the theory of non-linear thermal and diffusive waves in finite mass and reacting media, (3) the development of algorithms for the Helmholtz equation, (4) progress in the development of theory for Queer Differential Equations, and (5) spectral theory of non-elliptic operators.
Thermodynamic constraints on fluctuation phenomena
Maroney, O. J. E.
2009-12-01
The relationships among reversible Carnot cycles, the absence of perpetual motion machines, and the existence of a nondecreasing globally unique entropy function form the starting point of many textbook presentations of the foundations of thermodynamics. However, the thermal fluctuation phenomena associated with statistical mechanics has been argued to restrict the domain of validity of this basis of the second law of thermodynamics. Here we demonstrate that fluctuation phenomena can be incorporated into the traditional presentation, extending rather than restricting the domain of validity of the phenomenologically motivated second law. Consistency conditions lead to constraints upon the possible spectrum of thermal fluctuations. In a special case this uniquely selects the Gibbs canonical distribution and more generally incorporates the Tsallis distributions. No particular model of microscopic dynamics need be assumed.
Quantum entanglement and temperature fluctuations.
Ourabah, Kamel; Tribeche, Mouloud
2017-04-01
In this paper, we consider entanglement in a system out of equilibrium, adopting the viewpoint given by the formalism of superstatistics. Such an approach yields a good effective description for a system in a slowly fluctuating environment within a weak interaction between the system and the environment. For this purpose, we introduce an alternative version of the formalism within a quantum mechanical picture and use it to study entanglement in the Heisenberg XY model, subject to temperature fluctuations. We consider both isotropic and anisotropic cases and explore the effect of different temperature fluctuations (χ^{2}, log-normal, and F distributions). Our results suggest that particular fluctuations may enhance entanglement and prevent it from vanishing at higher temperatures than those predicted for the same system at thermal equilibrium.
Graphene surface plasmons mediated thermal radiation
Li, Jiayu; Liu, Baoan; Shen, Sheng
2018-02-01
A graphene nanostructure can simultaneously serve as a plasmonic optical resonator and a thermal emitter when thermally heated up. The unique electronic and optical properties of graphene have rendered tremendous potential in the active manipulation of light and the microscopic energy transport in nanostructures. Here we show that the thermally pumped surface plasmonic modes along graphene nanoribbons could dramatically modulate their thermal emission spectra in both near- and far-fields. Based on the fluctuating surface current method implemented by the resistive boundary method, we directly calculate the thermal emission spectrum from single graphene ribbons and vertically paired graphene ribbons. Furthermore, we demonstrate that both the near- and far-field thermal emission from graphene nanostructures can be optimized by tuning the chemical potential of doped graphene. The general guideline to maximize the thermal emission is illustrated by the our recently developed theory on resonant thermal emitters modulated by quasi-normal modes.
Thermal performance of Danish solar combi systems in practice and in theory
DEFF Research Database (Denmark)
Andersen, Elsa; Shah, Louise Jivan; Furbo, Simon
2004-01-01
An overview of measured thermal performances of Danish solar combi systems in practice is given. The thermal performance varies greatly from system to system. Measured and calculated thermal performances of different solar combi systems are compared and the main reasons for the different thermal...... performances are given. Further, a parametric study on two solar combi system types is performed. Based on the investigation it can be concluded that the thermal performance first of all is influenced by the space heating consumption during the summer period and that the systems in practice perform...
Computer simulations of phospholipid - membrane thermodynamic fluctuations
DEFF Research Database (Denmark)
Pedersen, U.R.; Peters, Günther H.j.; Schröder, T.B.
2008-01-01
This paper reports all-atom computer simulations of five phospholipid membranes, DMPC, DPPC, DMPG, DMPS, and DMPSH, with a focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and order parameter. For the slow fluctuations at constant temperature and pressure (defined...
Poshiwa, X.; Groeneveld, R.A.; Heitkonig, I.M.A.; Prins, H.H.T.; Ierland, van E.C.
2013-01-01
Annual rural incomes in Southern Africa show large rainfall-induced fluctuations. Variable rainfall has serious implications for agro-pastoral activities (crop cultivation and livestock keeping), whereas wildlife and tourism are less affected. The aim of this paper is to investigate the role of
Molecular evolution under fitness fluctuations.
Mustonen, Ville; Lässig, Michael
2008-03-14
Molecular evolution is a stochastic process governed by fitness, mutations, and reproductive fluctuations in a population. Here, we study evolution where fitness itself is stochastic, with random switches in the direction of selection at individual genomic loci. As the correlation time of these fluctuations becomes larger than the diffusion time of mutations within the population, fitness changes from an annealed to a quenched random variable. We show that the rate of evolution has its maximum in the crossover regime, where both time scales are comparable. Adaptive evolution emerges in the quenched fitness regime (evidence for such fitness fluctuations has recently been found in genomic data). The joint statistical theory of reproductive and fitness fluctuations establishes a conceptual connection between evolutionary genetics and statistical physics of disordered systems.
Kamata, Shunichi
2018-01-01
Solid-state thermal convection plays a major role in the thermal evolution of solid planetary bodies. Solving the equation system for thermal evolution considering convection requires 2-D or 3-D modeling, resulting in large calculation costs. A 1-D calculation scheme based on mixing length theory (MLT) requires a much lower calculation cost and is suitable for parameter studies. A major concern for the MLT scheme is its accuracy due to a lack of detailed comparisons with higher dimensional schemes. In this study, I quantify its accuracy via comparisons of thermal profiles obtained by 1-D MLT and 3-D numerical schemes. To improve the accuracy, I propose a new definition of the mixing length (l), which is a parameter controlling the efficiency of heat transportation due to convection, for a bottom-heated convective layer. Adopting this new definition of l, I investigate the thermal evolution of Saturnian icy satellites, Dione and Enceladus, under a wide variety of parameter conditions. Calculation results indicate that each satellite requires several tens of GW of heat to possess a thick global subsurface ocean suggested from geophysical analyses. Dynamical tides may be able to account for such an amount of heat, though the reference viscosity of Dione's ice and the ammonia content of Dione's ocean need to be very high. Otherwise, a thick global ocean in Dione cannot be maintained, implying that its shell is not in a minimum stress state.
Dual Phase Change Thermal Diodes for Enhanced Rectification Ratios: Theory and Experiment
Cottrill, Anton L.
2018-01-15
Thermal diodes are materials that allow for the preferential directional transport of heat and are highly promising devices for energy conservation, energy harvesting, and information processing applications. One form of a thermal diode consists of the junction between a phase change and phase invariant material, with rectification ratios that scale with the square root of the ratio of thermal conductivities of the two phases. In this work, the authors introduce and analyse the concept of a Dual Phase Change Thermal Diode (DPCTD) as the junction of two phase change materials with similar phase boundary temperatures but opposite temperature coefficients of thermal conductivity. Such systems possess a significantly enhanced optimal scaling of the rectification ratio as the square root of the product of the thermal conductivity ratios. Furthermore, the authors experimentally design and fabricate an ambient DPCTD enabled by the junction of an octadecane-impregnated polystyrene foam, polymerized using a high internal phase emulsion template (PFH-O) and a poly(N-isopropylacrylamide) (PNIPAM) aqueous solution. The DPCTD shows a significantly enhanced thermal rectification ratio both experimentally (2.6) and theoretically (2.6) as compared with ideal thermal diodes composed only of the constituent materials.
Fluctuation theorems for stochastic dynamics
Harris, R. J.; Schütz, G. M.
2007-07-01
Fluctuation theorems make use of time reversal to make predictions about entropy production in many-body systems far from thermal equilibrium. Here we review the wide variety of distinct, but interconnected, relations that have been derived and investigated theoretically and experimentally. Significantly, we demonstrate, in the context of Markovian stochastic dynamics, how these different fluctuation theorems arise from a simple fundamental time-reversal symmetry of a certain class of observables. Appealing to the notion of Gibbs entropy allows for a microscopic definition of entropy production in terms of these observables. We work with the master equation approach, which leads to a mathematically straightforward proof and provides direct insight into the probabilistic meaning of the quantities involved. Finally, we point to some experiments that elucidate the practical significance of fluctuation relations.
National Research Council Canada - National Science Library
Iñigo Antepara
2015-01-01
.... Every catalogue list of any material producer of mineral wool contains thermal conductivity, sometimes also specific heat capacity, but they give only single characteristic values for dry state of material mostly...
Electrostatic fluctuations in soap films.
Dean, D S; Horgan, R R
2002-06-01
A field theory to describe electrostatic interactions in soap films, described by electric multilayers with a generalized thermodynamic surface-charging mechanism, is studied. In the limit where the electrostatic interactions are weak, this theory is exactly soluble. The theory incorporates in a consistent way, the surface-charging mechanism and the fluctuations in the electrostatic field that correspond to the zero-frequency component of the van der Waals force. It is shown that these terms lead to a Casimir-like attraction that can be sufficiently large to explain the transition between the common black film to a Newton black film.
Molnár, Péter K; Sckrabulis, Jason P; Altman, Karie A; Raffel, Thomas R
2017-10-01
Climate change will affect host-parasite dynamics in complex ways. The development of forecast models is necessary for proactive disease management, but past studies have frequently reported thermal performance data in idiosyncratic ways that have limited use for parameterizing thermal host-parasite models. Development of improved forecast models will require strong collaborations between experimental parasitologists and disease modelers. The purpose of this article is to facilitate such collaborations by reviewing practical considerations for describing thermal performance curves of parasite and host performance traits, and using them to predict climate change impacts on host-parasite systems. In the first section, we provide an overview of how thermal performance curves can be embedded in life-cycle-based dynamical models of parasitism, and we outline how such models can capture the net effect of multiple nonlinear temperature dependencies affecting the host-parasite dynamics. We also discuss how macroecological generalities based on the metabolic theory of ecology (MTE) can be used to determine a priori parameter estimates for thermal performance curves to derive null models for data-deficient species, but we note that most of the generalities suggested by MTE remain to be tested for parasites. In the second section, we discuss empirical knowledge gaps for the temperature dependence of parasite and host performance traits, and we outline the types of data that need to be collected to inform MTE-based models for data-deficient species. We specifically emphasize the importance of (1) capturing the entire thermal response of performance traits, including lower and upper temperature thresholds, and (2) experimentally or statistically separating out the thermal responses of different performance traits (e.g., development and mortality) rather than only reporting composite measures (e.g., apparent development). Not adhering to these principles can lead to biased
Finite-temperature effective boundary theory of the quantized thermal Hall effect
Nakai, Ryota; Ryu, Shinsei; Nomura, Kentaro
2015-01-01
A finite-temperature effective free energy of the boundary of a quantized thermal Hall system is derived microscopically from the bulk two-dimensional Dirac fermion coupled with a gravitational field. In two spatial dimensions, the thermal Hall conductivity of fully gapped insulators and superconductors is quantized and given by the bulk Chern number, in analogy to the quantized electric Hall conductivity in quantum Hall systems. From the perspective of effective action functionals, two disti...
Matubayasi, Nobuyuki; Takahashi, Hideaki
2012-01-28
The relationship is investigated for QM/MM (quantum-mechanical/molecular-mechanical) systems between the fluctuations of the electronic state of the QM subsystem and of the solvation effect due to the QM-MM interaction. The free-energy change due to the electron-density fluctuation around its average is highlighted, and is evaluated through an approximate functional formulated in terms of distribution functions of the many-body coupling (pairwise non-additive) part of the QM-MM interaction energy. A set of QM/MM simulations are conducted in MM water solvent for QM water solute in ambient and supercritical conditions and for QM glycine solute in the neutral and zwitterionic forms. The variation of the electronic distortion energy of the QM solute in the course of QM/MM simulation is then shown to be compensated by the corresponding variation of the free energy of solvation. The solvation free energy conditioned by the electronic distortion energy is further analyzed with its components. It is found that the many-body contribution is essentially equal between the free energy and the average sum of solute-solvent interaction energy. © 2012 American Institute of Physics
1984-05-28
liquid or gas, ibid. 133(5) , 257-262 (1901). 1903 J. Boussinesq, Theorie Analytique de la Chaleur (Gauthier- Villars, Paris, 1903), Vol. 2, p...to the mechanical resistance, Philosophical Magazine (6)4_1, 899-908 (June 1921). E. Pohlhausen, The heat exchange between solid bodies and liquids
Quantum-gravity fluctuations and the black-hole temperature
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Institute, Jerusalem (Israel)
2015-05-15
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the discrete quantum spectrum suggested by Bekenstein with the continuous semi-classical spectrum suggested by Hawking? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quantized black-hole radiation spectrum. Remarkably, it is shown that this characteristic temperature of the discrete (quantized) black-hole radiation agrees with the well-known Hawking temperature of the continuous (semi-classical) black-hole spectrum. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Kelly, F. A.; Stacey, W. M.; Rapp, J.; Brix, M.
2001-07-01
The density limits for a series of shots in TEXTOR [Tokamak Experiment for Technology Oriented Research, E. Hintz, P. Bogen, H. A. Claa{ss}en , in Contributions to High-Temperature Plasma Physics, edited by K. H. Spatschek and J. Uhlenbusch (Akademie Verlag, Berlin, 1994, p. 373)], over a range of heating powers, that ended in multifaceted asymmetric radiation from the edge (MARFE) have been analyzed within the context of thermal instability theory. The prediction of MARFE onset agrees with observation to within the experimental uncertainty.
Effect of thermal loading due to laser pulse on thermoelastic porous medium under G-N theory
Directory of Open Access Journals (Sweden)
Mohamed I.A. Othman
Full Text Available The aim of this paper is to study the wave propagation of generalized thermoelastic medium with voids under the effect of thermal loading due to laser pulse with energy dissipation. The material is a homogeneous isotropic elastic half-space and heated by a non-Gaussian laser beam with the pulse duration of 0.2â¯ps. A normal mode method is proposed to analyse the problem and obtain numerical solutions for the displacement components, stresses, temperature distribution and the change in the volume fraction field. The results of the physical quantities have been illustrated graphically by comparison between both types II and III of Green-Naghdi theory for two values of time, as well as with and without void parameters. Keywords: Laser pulse, Voids, Energy dissipation, Green-Naghdi theory, Wave propagation, Thermoelasticity
Energy Technology Data Exchange (ETDEWEB)
Hassel, E.; Meinke, S.; Nocke, J.; Huebel, M. [Rostock Univ. (Germany). Inst. of Technical Thermodynamics; Ziems, C.; Weber, H. [Rostock Univ. (Germany). Inst. of Electrical Power Engineering
2012-07-01
In this paper, a way to investigate the influence of increasing wind and solar energy on thermal power plants is presented, reaching from a top level model for the electrical grid down to models for specific power plants including a detailed analysis of particular components of these plants. The global model structure and the simulation procedure consist of several steps. First, history data for wind, solar and conventional electricity production in Germany for the year 2010 is collected. With the predicted buildup of wind and solar energy we project a number of future scenarios. Using this data we estimate the operation schedule for different types of plants in Germany and we prescribe these schedules for our example power plants Rostock and Mainz-Wiesbaden, taking into account the merit order caused by the cost structure of the different plants. This operation schedule is the input into the detailed transient thermodynamic models. These plant models are able to capture the temporal behavior of all important parts of these fossil plants. Therefore physical equations and material properties as well as geometrical information for thousands of components are implemented in each model. Based on the thermodynamic properties calculated for every part, thermal and mechanical stress in critical components is computed and quantitative lifetime assessment is done, using different structural mechanical approaches. Then control loop modifications, repowering strategies and requirements for new power plants are developed. Also optimization strategies can be examined regarding parameters like efficiency, CO{sub 2} emissions, lifetime and operation costs. (orig.)
The fluctuation Hall conductivity and the Hall angle in type-II superconductor under magnetic field
Energy Technology Data Exchange (ETDEWEB)
Tinh, Bui Duc, E-mail: tinhbd@hnue.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam); Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Hoc, Nguyen Quang; Thu, Le Minh [Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
2016-02-15
Highlights: • The time-dependent Ginzburg–Landau was used to calculate fluctuation Hall conductivity and Hall angle in type-II superconductor in 2D and 3D. • We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. • The results were compared to the experimental data on YBCO. - Abstract: The fluctuation Hall conductivity and the Hall angle, describing the Hall effect, are calculated for arbitrary value of the imaginary part of the relaxation time in the frame of the time-dependent Ginzburg–Landau theory in type II-superconductor with thermal noise describing strong thermal fluctuations. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in dynamics. We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. The results are compared with experimental data on high-T{sub c} superconductor.
Unified optical-thermal four-stream radiative transfer theory for homogeneous vegetation canopies
Verhoef, W.; Xiao, Q.; Jia, L.; Su, Z.
2007-01-01
Foliage and soil temperatures are key variables for assessing the exchanges of turbulent heat fluxes between vegetated land and the atmosphere. Using multiple-view-angle thermal-infrared (TIR) observations, the temperatures of soil and vegetation may be retrieved. However, particularly for sparsely
Pal, Dulal; Talukdar, Babulal
2012-04-01
The influence of thermal radiation and first-order chemical reaction on unsteady MHD convective flow, heat and mass transfer of a viscous incompressible electrically conducting fluid past a semi-infinite vertical flat plate in the presence of transverse magnetic field under oscillatory suction and heat source in slip-flow regime is studied. The dimensionless governing equations for this investigation are formulated and solved analytically using two-term harmonic and non-harmonic functions. Comparisons with previously published work on special cases of the problem are performed and results are found to be in excellent agreement. A parametric study illustrating the effects of various physical parameters on the fluid velocity, temperature and concentration fields as well as skin-friction coefficient, the Nusselt and Sherwood numbers in terms of amplitude and phase is conducted. The numerical results of this parametric study are presented graphically and in tabular form to highlight the physical aspects of the problem.
A Model of Thermal Conductivity for Planetary Soils. 2; Theory for Cemented Soils
Piqueux, S.; Christensen, P. R.
2009-01-01
A numerical model of heat conduction through particulate media made of spherical grains cemented by various bonding agents is presented. The pore-filling gas conductivity, volume fraction, and thermal conductivity of the cementing phase are tunable parameters. Cement fractions conductivity. A significant conductivity increase (factor 3-8) is observed for bond fractions of 0.01 to 1% in volume. In the 1 to 15% bond fraction domain, the conductivity increases continuously but less intensely (25-100% conductivity increase compared to a 1% bond system). Beyond 15% of cements, the conductivity increases vigorously and the bulk conductivity rapidly approaches that of bedrock. The composition of the cements (i.e. conductivity) has little influence on the bulk thermal inertia of the soil, especially if the volume of bond <10%. These results indicate that temperature measurements are sufficient to detect cemented soils and quantify the amount of cementing phase, but the mineralogical nature of the bonds and the typical grain size are unlikely to be determined from orbit. On Mars, a widespread surface unit characterized by a medium albedo (0.19-0.26) and medium/high thermal inertia (200-600 J s(0.5)/sq m/K) has long been hypothesized to be associated with a duricrust. The fraction of cement required to fit the thermal data is less than approx.1-5% by volume. This small amount of material is consistent with orbital observations, confirming that soil cementation is an important factor controlling the thermal inertia of the Martian surface
Directory of Open Access Journals (Sweden)
Lorenzo Marcucci
Full Text Available Muscular force generation in response to external stimuli is the result of thermally fluctuating, cyclical interactions between myosin and actin, which together form the actomyosin complex. Normally, these fluctuations are modelled using transition rate functions that are based on muscle fiber behaviour, in a phenomenological fashion. However, such a basis reduces the predictive power of these models. As an alternative, we propose a model which uses direct single molecule observations of actomyosin fluctuations reported in the literature. We precisely estimate the actomyosin potential bias and use diffusion theory to obtain a brownian ratchet model that reproduces the complete cross-bridge cycle. The model is validated by simulating several macroscopic experimental conditions, while its interpretation is compatible with two different force-generating scenarios.
Energy Technology Data Exchange (ETDEWEB)
Kaellblad, K.
1998-05-01
The need to estimate indoor temperatures, heating or cooling load and energy requirements for buildings arises in many stages of a buildings life cycle, e.g. at the early layout stage, during the design of a building and for energy retrofitting planning. Other purposes are to meet the authorities requirements given in building codes. All these situations require good calculation methods. The main purpose of this report is to present the authors work with problems related to thermal models and calculation methods for determination of temperatures and heating or cooling loads in buildings. Thus the major part of the report deals with treatment of solar radiation in glazing systems, shading of solar and sky radiation and the computer program JULOTTA used to simulate the thermal behavior of rooms and buildings. Other parts of thermal models of buildings are more briefly discussed and included in order to give an overview of existing problems and available solutions. A brief presentation of how thermal models can be built up is also given and it is a hope that the report can be useful as an introduction to this part of building physics as well as during development of calculation methods and computer programs. The report may also serve as a help for the users of energy related programs. Independent of which method or program a user choose to work with it is his or her own responsibility to understand the limits of the tool, else wrong conclusions may be drawn from the results 52 refs, 22 figs, 4 tabs
Energy beyond food: foraging theory informs time spent in thermals by a large soaring bird.
Directory of Open Access Journals (Sweden)
Emily L C Shepard
Full Text Available Current understanding of how animals search for and exploit food resources is based on microeconomic models. Although widely used to examine feeding, such constructs should inform other energy-harvesting situations where theoretical assumptions are met. In fact, some animals extract non-food forms of energy from the environment, such as birds that soar in updraughts. This study examined whether the gains in potential energy (altitude followed efficiency-maximising predictions in the world's heaviest soaring bird, the Andean condor (Vultur gryphus. Animal-attached technology was used to record condor flight paths in three-dimensions. Tracks showed that time spent in patchy thermals was broadly consistent with a strategy to maximise the rate of potential energy gain. However, the rate of climb just prior to leaving a thermal increased with thermal strength and exit altitude. This suggests higher rates of energetic gain may not be advantageous where the resulting gain in altitude would lead to a reduction in the ability to search the ground for food. Consequently, soaring behaviour appeared to be modulated by the need to reconcile differing potential energy and food energy distributions. We suggest that foraging constructs may provide insight into the exploitation of non-food energy forms, and that non-food energy distributions may be more important in informing patterns of movement and residency over a range of scales than previously considered.
Vertical natural convection: application of the unifying theory of thermal convection
Ng, C.S.; Ooi, A.; Lohse, Detlef; Chung, D.
2015-01-01
Results from direct numerical simulations of vertical natural convection at Rayleigh numbers 1.0×10 5 –1.0×10 9 and Prandtl number 0.709 support a generalised applicability of the Grossmann–Lohse (GL) theory, which was originally developed for horizontal natural (Rayleigh–Bénard) convection. In
Facchi, Paolo; Garnero, Giancarlo; Ligabò, Marilena
2017-01-01
We present here a set of lecture notes on exact fluctuation relations. We prove the Jarzynski equality and the Crooks fluctuation theorem, two paradigmatic examples of classical fluctuation relations. Finally we consider their quantum versions, and analyze analogies and differences with the classical case.
Biomass ignition in mills and storages – is it explained by conventional thermal ignition theory?
DEFF Research Database (Denmark)
Schwarzer, Lars; Jensen, Peter Arendt; Glarborg, Peter
of the process, which can then be incorporated into refined models of self-ignition for biomass and other organic solids. In the present study, the slow, transient heating of several lignocellulosic biomasses and a bituminous coal from ambient temperature to around 300° C were investigated in a lab scale tube......, suggesting that a heterogeneous oxidation is the dominating mechanism in self-ignition. It could also be shown that both mechanisms compete for reactive material. While oxidation was exothermic, pyrolysis was largely thermally neutral in these experiments. Reaction behavior was seen to depend highly...
Bar-Cohen, Avram; Sheehan, Jessica R.; Rahim, Emil
2012-01-01
A comprehensive literature review and analysis of recent microchannel/microgap heat transfer data for two-phase flow of refrigerants and dielectric liquids is presented. The flow regime progression in such a microgap channel is shown to be predicted by the traditional flow regime maps. Moreover, Annular flow is shown to be the dominant regime for this thermal transport configuration and to grow in importance as the channel diameter decreases. The results of heat transfer studies of single miniature channels, as well as the analysis and inverse calculation of IR images of a heated microgap channel wall, are used to identify the existence of a characteristic M-shaped heat transfer coefficient variation with quality (or superficial velocity), with inflection points corresponding to transitions in the two-phase cooling modalities. For the high-quality, Annular flow conditions, the venerable Chen correlation is shown to yield predictive agreement for microgap channels that is comparable to that attained for macrochannels and to provide a mechanistic context for the thermal transport rates attained in microgap channels. Results obtained from infrared imaging, revealing previously undetected, large surface temperature variations in Annular flow, are also reviewed and related to the termination of the favorable thin-film evaporation mode in such channels.
Two beam surface fluctuation specular reflection spectroscopy.
Raudsepp, Allan; Fretigny, Christian; Lequeux, François; Talini, Laurence
2012-01-01
In surface fluctuation specular reflection spectroscopy (SFSRS) deflections of a specularly reflected laser beam are used to characterize thermally excited surface waves. Here we report on a new two beam version of SFSRS in which the deflections of two reflected laser beams from separate locations on a surface are correlated. We demonstrate that this new two beam SFSRS technique can be used to determine directly the power spectrum of height fluctuation of thermally excited surface waves over a large range of both frequencies and wavevectors. In addition, we show that the technique is well suited for materials ranging from simple liquids to complex liquids and soft solids, including turbid materials.
Miller, Steven David
1999-10-01
: these describe the collapse as a conserved flow of probability. A solution was found in the dilute limit of weak fluctuations where the EFP equation is linearized. There is zero probability that the star collapses to a singular state in the presence of background vacuum fluctuations, but the singularity returns with unit probability when the fluctuations are reduced to zero. Finally, an EFP equation was considered with respect to standard exterior coordinates. Using the thermal Brownian motion paradigm, an exact stationary or equilibrium solution was found in the infinite standard time relaxation limit. The solution gives the conditions required for the final collapsed object (a black hole) to be in thermal equilibrium with the background vacuum fluctuations. From this solution, one recovers the Hawking temperature without using field theory. The stationary solution then seems to correspond to a black hole in thermal equilibrium with a fluctuating conformal scalar field; or the Hawking-Hartle state.
Emergent "Quantum" Theory in Complex Adaptive Systems.
Minic, Djordje; Pajevic, Sinisa
2016-04-30
Motivated by the question of stability, in this letter we argue that an effective quantum-like theory can emerge in complex adaptive systems. In the concrete example of stochastic Lotka-Volterra dynamics, the relevant effective "Planck constant" associated with such emergent "quantum" theory has the dimensions of the square of the unit of time. Such an emergent quantum-like theory has inherently non-classical stability as well as coherent properties that are not, in principle, endangered by thermal fluctuations and therefore might be of crucial importance in complex adaptive systems.
A Generalization of Electromagnetic Fluctuation-Induced Casimir Energy
Directory of Open Access Journals (Sweden)
Yi Zheng
2015-01-01
Full Text Available Intermolecular forces responsible for adhesion and cohesion can be classified according to their origins; interactions between charges, ions, random dipole—random dipole (Keesom, random dipole—induced dipole (Debye are due to electrostatic effects; covalent bonding, London dispersion forces between fluctuating dipoles, and Lewis acid-base interactions are due to quantum mechanical effects; pressure and osmotic forces are of entropic origin. Of all these interactions, the London dispersion interaction is universal and exists between all types of atoms as well as macroscopic objects. The dispersion force between macroscopic objects is called Casimir/van der Waals force. It results from alteration of the quantum and thermal fluctuations of the electrodynamic field due to the presence of interfaces and plays a significant role in the interaction between macroscopic objects at micrometer and nanometer length scales. This paper discusses how fluctuational electrodynamics can be used to determine the Casimir energy/pressure between planar multilayer objects. Though it is confirmation of the famous work of Dzyaloshinskii, Lifshitz, and Pitaevskii (DLP, we have solved the problem without having to use methods from quantum field theory that DLP resorted to. Because of this new approach, we have been able to clarify the contributions of propagating and evanescent waves to Casimir energy/pressure in dissipative media.
Energy Technology Data Exchange (ETDEWEB)
Grekas, Denis N.; Frangopoulos, Christos A. [National Technical University of Athens, Zografou (Greece). Department of Naval Architecture and Marine Engineering
2007-11-15
During the synthesis optimisation of an energy system, the configuration changes and there is need to adapt properly the mathematical model of the system. A method is presented here for the automatic synthesis of the model itself of the energy system, which is based on the graph theory. The topology of the graph is stored in the computer memory and the computer model of the respective system is constructed automatically by Object Oriented Programming. The modelling diagram of the system is introduced by an Application Programming Interface. A combined-cycle system serves as an application example. The method has been proved efficient and convenient. (author)
Nematollahi, Mohammad Sadegh; Mohammadi, Hossein; Nematollahi, Mohammad Ali
2017-11-01
In this paper, a new formulation for analyzing free vibration of thin rectangular nanoplates under different thermal conditions is obtained based on the higher-order nonlocal strain gradient theory. Governing equations and non-classical boundary conditions of the nanoplate are derived by using the variational approach. The exact solution is obtained as a function of higher-order and lower-order nonlocal parameters, strain gradient length scale and temperature difference using Navier solution procedure. The influences of small-scale parameters on the vibrational behavior of the nanoplate are investigated for various thermal conditions. High and low temperature conditions are considered to study the effects of changes in temperature and small-scale parameters. It has been shown that increasing the nonlocal parameters decrease the natural frequency of the nanoplate, while increasing the strain gradient length scale will increase it. Also, the natural frequency of the nanoplate will increase by increasing the temperature difference in low temperature conditions, but it will decrease by increasing the temperature difference in high temperature conditions. Non-uniform behaviors are reported for some cases and softening effect and hardening effect are studied. To validate the solutions, the results are compared with previous researches.
Kink fluctuation asymptotics and zero modes
Energy Technology Data Exchange (ETDEWEB)
Izquierdo, A.A. [Universidad de Salamanca, Departamento de Matematica Aplicada and IUFFyM, Salamanca (Spain); Guilarte, J.M. [Universidad de Salamanca, Departamento de Fisica Fundamental and IUFFyM, Salamanca (Spain)
2012-10-15
In this paper we propose a refinement of the heat-kernel/zeta function treatment of kink quantum fluctuations in scalar field theory, further analyzing the existence and implications of a zero-energy fluctuation mode. Improved understanding of the interplay between zero modes and the kink heat-kernel expansion delivers asymptotic estimations of one-loop kink mass shifts with remarkably higher precision than previously obtained by means of the standard Gilkey-DeWitt heat-kernel expansion. (orig.)
Inverse scattering problem in turbulent magnetic fluctuations
Directory of Open Access Journals (Sweden)
R. A. Treumann
2016-08-01
Full Text Available We apply a particular form of the inverse scattering theory to turbulent magnetic fluctuations in a plasma. In the present note we develop the theory, formulate the magnetic fluctuation problem in terms of its electrodynamic turbulent response function, and reduce it to the solution of a special form of the famous Gelfand–Levitan–Marchenko equation of quantum mechanical scattering theory. The last of these applies to transmission and reflection in an active medium. The theory of turbulent magnetic fluctuations does not refer to such quantities. It requires a somewhat different formulation. We reduce the theory to the measurement of the low-frequency electromagnetic fluctuation spectrum, which is not the turbulent spectral energy density. The inverse theory in this form enables obtaining information about the turbulent response function of the medium. The dynamic causes of the electromagnetic fluctuations are implicit to it. Thus, it is of vital interest in low-frequency magnetic turbulence. The theory is developed until presentation of the equations in applicable form to observations of turbulent electromagnetic fluctuations as input from measurements. Solution of the final integral equation should be done by standard numerical methods based on iteration. We point to the possibility of treating power law fluctuation spectra as an example. Formulation of the problem to include observations of spectral power densities in turbulence is not attempted. This leads to severe mathematical problems and requires a reformulation of inverse scattering theory. One particular aspect of the present inverse theory of turbulent fluctuations is that its structure naturally leads to spatial information which is obtained from the temporal information that is inherent to the observation of time series. The Taylor assumption is not needed here. This is a consequence of Maxwell's equations, which couple space and time evolution. The inversion procedure takes
Population Genetics with Fluctuating Population Sizes
Chotibut, Thiparat; Nelson, David R.
2017-05-01
Standard neutral population genetics theory with a strictly fixed population size has important limitations. An alternative model that allows independently fluctuating population sizes and reproduces the standard neutral evolution is reviewed. We then study a situation such that the competing species are neutral at the equilibrium population size but population size fluctuations nevertheless favor fixation of one species over the other. In this case, a separation of timescales emerges naturally and allows adiabatic elimination of a fast population size variable to deduce the fluctuation-induced selection dynamics near the equilibrium population size. The results highlight the incompleteness of the standard population genetics with a strictly fixed population size.
Macroscopic realism of quantum work fluctuations
Blattmann, Ralf; Mølmer, Klaus
2017-07-01
We study the fluctuations of the work performed on a driven quantum system, defined as the difference between subsequent measurements of energy eigenvalues. These work fluctuations are governed by statistical theorems with similar expressions in classical and quantum physics. We show that we can distinguish quantum and classical work fluctuations, as the latter can be described by a macrorealistic theory and hence obey Leggett-Garg inequalities. We show that these inequalities are violated by quantum processes in a driven two-level system and in a harmonic oscillator subject to a squeezing transformation.
Goldman, Benjamin D.; Dowell, Earl H.; Scott, Robert C.
2014-01-01
Conical shell theory and piston theory aerodynamics are used to study the aeroelastic stability of the thermal protection system (TPS) on the NASA Hypersonic Inflatable Aerodynamic Decelerator (HIAD). Structural models of the TPS consist of single or multiple orthotropic conical shell systems resting on several circumferential linear elastic supports. The shells in each model may have pinned (simply-supported) or elastically-supported edges. The Lagrangian is formulated in terms of the generalized coordinates for all displacements and the Rayleigh-Ritz method is used to derive the equations of motion. The natural modes of vibration and aeroelastic stability boundaries are found by calculating the eigenvalues and eigenvectors of a large coefficient matrix. When the in-flight configuration of the TPS is approximated as a single shell without elastic supports, asymmetric flutter in many circumferential waves is observed. When the elastic supports are included, the shell flutters symmetrically in zero circumferential waves. Structural damping is found to be important in this case. Aeroelastic models that consider the individual TPS layers as separate shells tend to flutter asymmetrically at high dynamic pressures relative to the single shell models. Several parameter studies also examine the effects of tension, orthotropicity, and elastic support stiffness.
Thermalization and revivals after a quantum quench in conformal field theory.
Cardy, John
2014-06-06
We consider a quantum quench in a finite system of length L described by a 1+1-dimensional conformal field theory (CFT), of central charge c, from a state with finite energy density corresponding to an inverse temperature β≪L. For times t such that ℓ/2modular transformations. At early times t≪(Lβ)^{1/2} there is a universal decay F∼exp(-(πc/3)Lt^{2}/β(β^{2}+4t^{2})). The effect of an irrelevant nonintegrable perturbation of the CFT is to progressively broaden each revival at t=nL/2 by an amount O(n^{1/2}).
Magnetic Alfvén‐cyclotron fluctuations of anisotropic nonthermal plasmas
National Research Council Canada - National Science Library
Navarro, Roberto E; Muñoz, Víctor; Araneda, Jaime; Viñas, Adolfo F.‐; Moya, Pablo S; Valdivia, Juan A
2015-01-01
.... Here we study magnetic Alfvén‐cyclotron fluctuations propagating along a background magnetic field in a plasma composed of thermal and suprathermal protons and electrons via the fluctuation...
Mandelis, Andreas; Feng, Chris
2002-02-01
A three-dimensional theory of the frequency-domain thermal-wave field generated inside a turbid medium with optical and thermal properties of human tissue is presented. The optical source is treated as a three-dimensional harmonically modulated diffuse-photon-density wave (DPDW) field in the diffusion approximation of the radiative transfer theory. Unlike earlier Green-function-based theoretical models, exact boundary conditions are used based on the requirement that there should be no diffuse photon intensity entering the turbid medium from the outside. Explicit analytical expressions for the DPDW field and for the dependent thermal-wave field are obtained in the spatial Hankel-transform domain. The formalism is further extended to the calculation of the infrared photothermal radiometric signal arising from the nonradiatively generated thermal-wave distribution in turbid media with instantaneous nonradiative deexcitation as well as in media with nonzero fluorescence relaxation lifetimes. Numerical inversions have been performed and presented as examples of selected special cases of the theory. It is found that the present theory with exact DPDW-field boundary conditions is valid throughout the entire domain of the turbid medium, with the exception of the very near-surface ballistic photon "skin layer" (7-50 microm). Photothermal radiometric signals were found to be more reliably predicted than DPDW signals within this layer, due to the depth-integration nature of this detection methodology.
Chiral edge fluctuations of colloidal membranes
Jia, Leroy; Zakhary, Mark; Dogic, Zvonimir; Pelcovits, Robert; Powers, Thomas
Using experiments and theory we study chiral fluctuations of the edge of a nearly flat colloidal membrane, consisting of rod-like viruses held together by the depletion interaction. Our measurements show an anomalous peak in the power spectrum around 1 inverse micron. Using an effective theory to describe the liquid crystal degrees of freedom by geometric properties of the edge, such as length, geodesic torsion, and curvature, we calculate the spectrum of out-of-plane edge fluctuations. The peak arises for sufficiently strong chirality, and corresponds to the instability of a flat membrane to a shape with helical, rippled edges.
Fluctuations in a Spin Chain and the Entanglement Hamiltonian
Turner, Ari; Demler, Eugene
2014-03-01
How are quantum fluctuations and thermal fluctuations different in many-body systems? I will compare the variance of the fluctuations of spin in a segment of a spin chain in the ground state and at a finite temperature, showing that fluctuations in the ground state are much more correlated than in the thermal state. The full distribution function of spin can also be determined, and is non-Gaussian. These effects could possibly be measured in a chain of sodium atoms in an optical lattice. The method involves mapping the system to an imaginary thermal system called the ``entanglement Hamiltonian.'' Measuring the ground state fluctuations of the spin chain gives an indirect way of measuring the entanglement Hamiltonian.
Small Thermal Fluctuations on a Large Domain
Shiromizu, T.; Morikawa, M.
1996-07-01
Weak first-order phase transitions proceed with percolation of a new phase. The kinematics of this process is clarified from the point of view of subcritical bubbles. We exdamine the effect of small subcritical bubbles around a large domain of an asymmetric phase by introducing an effective geometry. The percolation process can be understood as a perpetual growth of the large domain aided by the small subcritical bubbles.
Energy Technology Data Exchange (ETDEWEB)
Aggarwal, M.M.; Ahammed, Z.; Angelis, A.L.S.; Antonenko, V.; Arefiev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bucher, D.; Buesching, H.; Carlen, L.; Chattopadhyay, S.; Das, A.C.; Decowski, M.P.; Donni, P.; Dubey, A.K.; Dutta Majumdar, M.R.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishcuk, O.; Geurts, F.J.M.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Loehner, H.; Mahapatra, D.P.; Manko, V.; Martin, M.; Miake, Y.; Mishra, G.C.; Mohanty, B.; Morrison, D.; Mukhopadhayay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nishimura, S.; Nomokov, P.; Petracek, V.; Plasil, F.; Purschke, M.L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.-R.; Schutz, Y.; Shabratova, G.; Sibiriak, I.; Siemiarczuk, T.; Sinha, B.C.; Slavine, N.; Soederstroem, K.; Sood, G.; Soerensen, S.P.; Stankus, P.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Trivedi, M.D.; Tsvetkov, A.; Tykarski, L.; Urbahn, J.; Eijinhoven, N. van; Niewenhuizen, G.J. van; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.; Voeroes, S.; Wyslouch, B.; Young, G.R
2003-03-10
Event-by-event fluctuations in the multiplicities of charged particles and photons at SPS energies are discussed. Fluctuations are studied by controlling the centrality of the reaction and rapidity acceptance of the detectors. Results are also presented on the event-by-event study of correlations between the multiplicity of charged particles and photons to search for DCC-like signals.
Mohanty, Bedangadas; Ahammed, Z.; Angelis, A.L.S.; Antonenko, V.; Arefev, V.; Astakhov, V.; Avdeitchikov, V.; Awes, T.C.; Baba, P.V.K.S.; Badyal, S.K.; Bathe, S.; Batiounia, B.; Bernier, T.; Bhalla, K.B.; Bhatia, V.S.; Blume, C.; Bucher, D.; Busching, H.; Carlen, L.; Chattopadhyay, S.; Das, A.C.; Decowski, M.P.; Donni, P.; Dubey, A.K.; Dutta Majumdar, M.R.; Enosawa, K.; Fokin, S.; Frolov, V.; Ganti, M.S.; Garpman, S.; Gavrishchuk, O.; Geurts, F.J.M.; Glasow, R.; Guskov, B.; Gustafsson, H.A.; Gutbrod, H.H.; Hrivnacova, I.; Ippolitov, M.; Kalechofsky, H.; Kamermans, R.; Karadjev, K.; Karpio, K.; Kolb, B.W.; Kosarev, I.; Koutcheryaev, I.; Kugler, A.; Kulinich, P.; Kurata, M.; Lebedev, A.; Lohne, H.; Mahapatra, D.P.; Manko, V.; Martin, M.; Miake, Y.; Mishra, G.C.; Morrison, D.; Mukhopadhyay, D.S.; Naef, H.; Nandi, B.K.; Nayak, S.K.; Nayak, T.K.; Nianine, A.; Nikitine, V.; Nikolaev, S.; Nishimura, S.; Nomokov, P.; Nystrand, J.; Oskarsson, A.; Otterlund, I.; Phatak, S.C.; Pavliouk, S.; Peitzmann, T.; Petracek, V.; Plasil, F.; Purschke, M.L.; Rak, J.; Raniwala, R.; Raniwala, S.; Rao, N.K.; Retiere, F.; Reygers, K.; Roland, G.; Rosselet, L.; Roufanov, I.; Rubio, J.M.; Sambyal, S.S.; Santo, R.; Sato, S.; Schlagheck, H.; Schmidt, H.R.; Schutz, Y.; Shabratova, G.; Sibiriak, I.; Siemiarczuk, T.; Sinha, B.C.; Slavine, N.; Soderstrom, K.; Sood, G.; Sorensen, S.P.; Stankus, P.; Stefanek, G.; Steinberg, P.; Stenlund, E.; Sumbera, M.; Svensson, T.; Trivedi, M.D.; Tsvetkov, A.; Tykarski, L.; Urbahn, J.; van Eijndhoven, N.; van Nieuwenhuizen, G.J.; Vinogradov, A.; Viyogi, Y.P.; Vodopianov, A.S.; Voros, S.; Wyslouch, B.; Young, G.R.; Mohanty, Bedangadas
2003-01-01
Event-by-event fluctuations in the multiplicities of charged particles and photons at SPS energies are discussed. Fluctuations are studied by controlling the centrality of the reaction and rapidity acceptance of the detectors. Results are also presented on the event-by-event study of correlations between the multiplicity of charged particles and photons to search for DCC-like signals.
Open system trajectories specify fluctuating work but not heat.
Talkner, Peter; Hänggi, Peter
2016-08-01
Based on the explicit knowledge of a Hamiltonian of mean force, the classical statistical mechanics and equilibrium thermodynamics of open systems in contact with a thermal environment at arbitrary interaction strength can be formulated. Yet, even though the Hamiltonian of mean force uniquely determines the equilibrium phase space probability density of a strongly coupled open system, the knowledge of this probability density alone is insufficient to determine the Hamiltonian of mean force, needed in constructing the underlying statistical mechanics and thermodynamics. We demonstrate that under the assumption that the Hamiltonian of mean force is known, an extension of thermodynamic structures from the level of averaged quantities to fluctuating objects (i.e., a stochastic thermodynamics) is possible. However, such a construction undesirably also involves a vast ambiguity. This situation is rooted in the eminent lack of a physical guiding principle allowing us to distinguish a physically meaningful theory out of a multitude of other equally conceivable ones.
Spontaneous emission of magnetic field fluctuations in Solar wind-like suprathermal plasmas
Navarro, R.; Munoz, V.; Araneda, J. A.; Vinas, A. F.; Valdivia, J. A.
2013-12-01
Heavy ions in solar wind have been observed to flow faster than protons, with temperatures exceeding the mass proportionality respect to protons. The identification and explanation of the physical processes responsible for ion heating may provide the key to explain why the temperature of the outer solar atmosphere and expanding corona forming the solar wind is several orders of magnitude higher than that of the photosphere. Possible explanations of the preferential acceleration and heating of ions often involve linear kinetic theory, which allows for a wide number of heavily damped waves (or higher-order modes), which could play a secondary role in the energization of solar wind plasmas. Also, linear theory predicts instability thresholds in the temperature distribution of protons which are consistent with data from the Solar Wind Experiment (SWE). However, it has also been observed that proton velocity distributions appear to be strongly anisotropic, displaying a pronounced non-Maxwellian profile of particles exceeding thermal energies. These velocity distributions are often modeled with a family of specific functional describing both the low-energy Maxwellian core and the high-energy power-law tails, popularly known in the literature as kappa-distributions. Furthermore, short wavelength magnetic fluctuations with small amplitude are present even in the absence of plasma instabilities. These spontaneous fluctuations are intimately linked to the linear response of perturbations via the fluctuation-dissipation theorem. The various collective modes of fluctuations are constrained by the structure of the higher-order modes determined by the electromagnetic kinetic dispersion relation. In this work, we examine the propagation and excitation of parallel Alfvén-cyclotron waves in a suprathermal proton solar wind-like plasma, as described by a kappa-like distribution function, by taking care of the often ignored higher-order modes which modify the structure of the
Fluctuations of Intensive Quantities in Statistical Thermodynamics
Directory of Open Access Journals (Sweden)
Artur E. Ruuge
2013-11-01
Full Text Available In phenomenological thermodynamics, the canonical coordinates of a physical system split in pairs, with each pair consisting of an extensive quantity and an intensive one. In the present paper, the quasithermodynamic fluctuation theory of a model system of a large number of oscillators is extended to statistical thermodynamics based on the idea of perceiving the fluctuations of intensive variables as the fluctuations of specific extensive ones in a “thermodynamically dual” system. The extension is motivated by the symmetry of the problem in the context of an analogy with quantum mechanics, which is stated in terms of a generalized Pauli problem for the thermodynamic fluctuations. The doubled Boltzmann constant divided by the number of particles plays a similar role as the Planck constant.
Shahani, Amir Reza; Sharifi Torki, Hamid
2018-01-01
The thermoelasticity problem in a thick-walled orthotropic hollow cylinder is solved analytically using finite Hankel transform and Laplace transform. Time-dependent thermal and mechanical boundary conditions are applied on the inner and the outer surfaces of the cylinder. For solving the energy equation, the temperature itself is considered as boundary condition to be applied on both the inner and the outer surfaces of the orthotropic cylinder. Two different cases are assumed for solving the equation of motion: traction-traction problem (tractions are prescribed on both the inner and the outer surfaces) and traction-displacement (traction is prescribed on the inner surface and displacement is prescribed on the outer surface of the hollow orthotropic cylinder). Due to considering uncoupled theory, after obtaining temperature distribution, the dynamical structural problem is solved and closed-form relations are derived for radial displacement, radial and hoop stress. As a case study, exponentially decaying temperature with respect to time is prescribed on the inner surface of the cylinder and the temperature of the outer surface is considered to be zero. Owing to solving dynamical problem, the stress wave propagation and its reflections were observed after plotting the results in both cases.
Continuous information flow fluctuations
Rosinberg, Martin Luc; Horowitz, Jordan M.
2016-10-01
Information plays a pivotal role in the thermodynamics of nonequilibrium processes with feedback. However, much remains to be learned about the nature of information fluctuations in small-scale devices and their relation with fluctuations in other thermodynamics quantities, like heat and work. Here we derive a series of fluctuation theorems for information flow and partial entropy production in a Brownian particle model of feedback cooling and extend them to arbitrary driven diffusion processes. We then analyze the long-time behavior of the feedback-cooling model in detail. Our results provide insights into the structure and origin of large deviations of information and thermodynamic quantities in autonomous Maxwell's demons.
Computational techniques in queueing and fluctuation theory
Mohammad Asghari, N.
2014-01-01
The main objective of this thesis is to develop numerical techniques to calculate the probability distribution of the running maximum of Lévy processes, and consider a number of specific financial applications. The other objective is to propose a numerical method to optimize the energy consumption
Fluctuations of local electric field and dipole moments in water between metal walls
Takae, Kyohei; Onuki, Akira
2015-01-01
We examine the thermal fluctuations of the local electric field $E_k^{\\rm loc}$ and the dipole moment $\\mu_k$ in liquid water at $T=298$ K between metal walls in electric field applied in the perpendicular direction. We use analytic theory and molecular dynamics simulation. In this situation, there is a global electrostatic coupling between the surface charges on the walls and the polarization in the bulk. Then, the correlation function of the polarization density $p_z(r)$ along the applied f...
Scaling metabolic rate fluctuations
Labra, Fabio A.; Marquet, Pablo A.; Bozinovic, Francisco
2007-01-01
Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emerge...
Hwang, Gwangseok; Chung, Jaehun; Kwon, Ohmyoung
2014-11-01
The application of conventional scanning thermal microscopy (SThM) is severely limited by three major problems: (i) distortion of the measured signal due to heat transfer through the air, (ii) the unknown and variable value of the tip-sample thermal contact resistance, and (iii) perturbation of the sample temperature due to the heat flux through the tip-sample thermal contact. Recently, we proposed null-point scanning thermal microscopy (NP SThM) as a way of overcoming these problems in principle by tracking the thermal equilibrium between the end of the SThM tip and the sample surface. However, in order to obtain high spatial resolution, which is the primary motivation for SThM, NP SThM requires an extremely sensitive SThM probe that can trace the vanishingly small heat flux through the tip-sample nano-thermal contact. Herein, we derive a relation between the spatial resolution and the design parameters of a SThM probe, optimize the thermal and electrical design, and develop a batch-fabrication process. We also quantitatively demonstrate significantly improved sensitivity, lower measurement noise, and higher spatial resolution of the fabricated SThM probes. By utilizing the exceptional performance of these fabricated probes, we show that NP SThM can be used to obtain a quantitative temperature profile with nanoscale resolution independent of the changing tip-sample thermal contact resistance and without perturbation of the sample temperature or distortion due to the heat transfer through the air.
Thermal hair of a quantum black hole
Itoh, Y.; Hotta, M.; Futamase, T.; Morikawa, M.
1998-09-01
We reexamine the possibility which has been argued since just after the discovery of Hawking radiation: the statistical explanation of Bekenstein-Hawking entropy by counting quasibounded modes of thermal fluctuation in two-dimensional black hole spacetime. While string theory has made much progress recently, it may be still interesting to study black hole entropy with field theories. The black hole concerned is quantum in the sense that it is in thermal equilibrium with its Hawking radiation. It is shown that the fluctuation around such a black hole obeys a wave equation with a potential whose peaks are located near the black hole and which is caused by quantum effects. We can construct models in which the potential in the above sense has several positive peaks and there are quasibounded modes confined between these peaks. This suggests that these modes contribute to black hole entropy. However, it is shown that the entropy associated with these modes does not obey the ordinary area law. We can call these modes additional thermal hair of the quantum black hole. Therefore the situation for the possibility is more difficult and we might find other ways to explain the entropy. From recent progress counting the number of states in string theory, it becomes more convincing that we expect Bekenstein-Hawking entropy for the Schwarzschild black hole will be explained exactly from the string theoretical point of view.
Hydrodynamic fluctuations in thermostatted multiparticle collision dynamics.
Híjar, Humberto; Sutmann, Godehard
2011-04-01
In this work we study the behavior of mesoscopic fluctuations of a fluid simulated by Multiparticle Collision Dynamics when this is applied together with a local thermostatting procedure that constrains the strength of temperature fluctuations. We consider procedures in which the thermostat interacts with the fluid at every simulation step as well as cases in which the thermostat is applied only at regular time intervals. Due to the application of the thermostat temperature fluctuations are forced to relax to equilibrium faster than they do in the nonthermostatted, constant-energy case. Depending on the interval of application of the thermostat, it is demonstrated that the thermodynamic state changes gradually from isothermal to adiabatic conditions. In order to exhibit this effect we compute from simulations diverse correlation functions of the hydrodynamic fluctuating fields. These correlation functions are compared with those predicted by a linearized hydrodynamic theory of a simple fluid in which a thermostat is applied locally. We find a good agreement between the model and the numerical results, which confirms that hydrodynamic fluctuations in Multiparticle Collision Dynamics in the presence of the thermostat have the properties expected for spontaneous fluctuations in fluids in contact with a heat reservoir.
Crisanti, A; Sarracino, A; Zannetti, M
2017-05-01
We study analytically the probability distribution of the heat released by an ensemble of harmonic oscillators to the thermal bath, in the nonequilibrium relaxation process following a temperature quench. We focus on the asymmetry properties of the heat distribution in the nonstationary dynamics, in order to study the forms taken by the fluctuation theorem as the number of degrees of freedom is varied. After analyzing in great detail the cases of one and two oscillators, we consider the limit of a large number of oscillators, where the behavior of fluctuations is enriched by a condensation transition with a nontrivial phase diagram, characterized by reentrant behavior. Numerical simulations confirm our analytical findings. We also discuss and highlight how concepts borrowed from the study of fluctuations in equilibrium under symmetry-breaking conditions [Gaspard, J. Stat. Mech. (2012) P0802110.1088/1742-5468/2012/08/P08021] turn out to be quite useful in understanding the deviations from the standard fluctuation theorem.
Exchange fluctuation theorem for correlated quantum systems.
Jevtic, Sania; Rudolph, Terry; Jennings, David; Hirono, Yuji; Nakayama, Shojun; Murao, Mio
2015-10-01
We extend the exchange fluctuation theorem for energy exchange between thermal quantum systems beyond the assumption of molecular chaos, and describe the nonequilibrium exchange dynamics of correlated quantum states. The relation quantifies how the tendency for systems to equilibrate is modified in high-correlation environments. In addition, a more abstract approach leads us to a "correlation fluctuation theorem". Our results elucidate the role of measurement disturbance for such scenarios. We show a simple application by finding a semiclassical maximum work theorem in the presence of correlations. We also present a toy example of qubit-qudit heat exchange, and find that non-classical behaviour such as deterministic energy transfer and anomalous heat flow are reflected in our exchange fluctuation theorem.
Low Mach Number Fluctuating Hydrodynamics for Electrolytes
Péraud, Jean-Philippe; Chaudhri, Anuj; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L
2016-01-01
We formulate and study computationally the low Mach number fluctuating hydrodynamic equations for electrolyte solutions. We are interested in studying transport in mixtures of charged species at the mesoscale, down to scales below the Debye length, where thermal fluctuations have a significant impact on the dynamics. Continuing our previous work on fluctuating hydrodynamics of multicomponent mixtures of incompressible isothermal miscible liquids (A. Donev, et al., Physics of Fluids, 27, 3, 2015), we now include the effect of charged species using a quasielectrostatic approximation. Localized charges create an electric field, which in turn provides additional forcing in the mass and momentum equations. Our low Mach number formulation eliminates sound waves from the fully compressible formulation and leads to a more computationally efficient quasi-incompressible formulation. We demonstrate our ability to model saltwater (NaCl) solutions in both equilibrium and nonequilibrium settings. We show that our algorithm...
Classical and quantum temperature fluctuations via holography
Energy Technology Data Exchange (ETDEWEB)
Balatsky, Alexander V. [KTH Royal Inst. of Technology, Stockholm (Sweden); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gudnason, Sven Bjarke [KTH Royal Inst. of Technology, Stockholm (Sweden); Thorlacius, Larus [KTH Royal Inst. of Technology, Stockholm (Sweden); University of Iceland, Reykjavik (Iceland); Zarembo, Konstantin [KTH Royal Inst. of Technology, Stockholm (Sweden); Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Uppsala Univ. (Sweden); Krikun, Alexander [KTH Royal Inst. of Technology, Stockholm (Sweden); Inst. of Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation); Kedem, Yaron [KTH Royal Inst. of Technology, Stockholm (Sweden)
2014-05-27
We study local temperature fluctuations in a 2+1 dimensional CFT on the sphere, dual to a black hole in asymptotically AdS space-time. The fluctuation spectrum is governed by the lowest-lying hydrodynamic sound modes of the system whose frequency and damping rate determine whether temperature fluctuations are thermal or quantum. We calculate numerically the corresponding quasinormal frequencies and match the result with the hydrodynamics of the dual CFT at large temperature. As a by-product of our analysis we determine the appropriate boundary conditions for calculating low-lying quasinormal modes for a four-dimensional Reissner-Nordstrom black hole in global AdS.
Fluctuation theorems for continuously monitored quantum fluxes.
Campisi, Michele; Talkner, Peter; Hänggi, Peter
2010-10-01
It is shown that quantum fluctuation theorems remain unaffected if measurements of any kind and number of observables are performed during the action of a force protocol. That is, although the backward and forward probabilities entering the fluctuation theorems are both altered by these measurements, their ratio remains unchanged. This observation allows us to describe the measurement of fluxes through interfaces and, in this way, to bridge the gap between the current theory, based on only two measurements performed at the beginning and end of the protocol, and experiments that are based on continuous monitoring.
National Research Council Canada - National Science Library
Péter K Molnár; Jason P Sckrabulis; Karie A Altman; Thomas R Raffel
2017-01-01
.... The purpose of this article is to facilitate such collaborations by reviewing practical considerations for describing thermal performance curves of parasite and host performance traits, and using...
Modulations and Fluctuations in Lyotropic Smectic Liquid Crystals.
Wack, Daniel Christopher
This dissertation is concerned with modulation and fluctuation phenomena in lyotropic smectic liquid crystals. The first Chapter provides a critical summary of the results and suggestions for further experimental investigation. In Chapter 2, the results of a high resolution, synchrotron x-ray powder diffraction study of lattice constants in the P_{beta^' } ("rippled") phase of lecithin-water multilamellar mixtures are given. The variation with water volume fraction phi_{omega} and hydrocarbon chain length N_{c} of the modulation wavevector suggests that membrane curvature and hydration interactions between membranes play a significant role in the modulation. The results are consistent with a Lifshitz phenomenological model for lamellar phases of interacting membranes proposed by Goldstein and Leibler. The phase behavior predicted by the model includes a multicritical point called the Lifshitz Point where the wavelength of the modulation diverges. The experimental results indicate that this multicritical point lies in the vicinity of N_{c} = 9 and phi_{omega} = 0.18. In Chapter 3, a high-resolution synchrotron x-ray study of oriented, supported, hydrated dilaurylphosphatidylcholine in the L_{alpha} (Smectic A or "fluid") phase shows that thermal fluctuations give rise to algebraic decay of positional order in stacking of the bimolecular lamellae, the so-called "Landau-Peierls" state. For planar monocrystalline samples of thickness 10-20 mum, the exponents derived from intensity profiles are in accord with harmonic theory, and indicate a bulk compressional elastic constant B = (1.9 +/- 1.0) x 10 ^8erg/cm^3. Samples of thickness ~ 1-2 mu m show anomalous behavior in the wings of the longitudinal intensity profiles, but are not in accord with harmonic theory, suggesting that surface effects partially quench the thermal fluctuations. In Chapter 4, investigation of the dipalmitoylphosphatidylcholine-cholesterol phase diagram by low and high resolution synchrotron x
Suppression of Temperature Fluctuations and Energy Barrier Generation by Velocity Shear
Boedo, J. A.; Terry, P. W.; Gray, D.; Ivanov, R. S.; Conn, R. W.; Jachmich, S.; van Oost, G.; Textor Team
2000-03-01
First measurements of temperature fluctuations in a region of high velocity shear show that absolute and normalized fluctuation levels are reduced across the shear layer, a result that is consistent with weak parallel electron thermal conduction in the electron temperature dynamics. The concomitant reduction of temperature, density, and electric field fluctuations reduces the anomalous conducted and convected heat fluxes.
Directory of Open Access Journals (Sweden)
V.M. Loktev
2008-09-01
Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.
Equilibrium & Nonequilibrium Fluctuation Effects in Biopolymer Networks
Kachan, Devin Michael
Fluctuation-induced interactions are an important organizing principle in a variety of soft matter systems. In this dissertation, I explore the role of both thermal and active fluctuations within cross-linked polymer networks. The systems I study are in large part inspired by the amazing physics found within the cytoskeleton of eukaryotic cells. I first predict and verify the existence of a thermal Casimir force between cross-linkers bound to a semi-flexible polymer. The calculation is complicated by the appearance of second order derivatives in the bending Hamiltonian for such polymers, which requires a careful evaluation of the the path integral formulation of the partition function in order to arrive at the physically correct continuum limit and properly address ultraviolet divergences. I find that cross linkers interact along a filament with an attractive logarithmic potential proportional to thermal energy. The proportionality constant depends on whether and how the cross linkers constrain the relative angle between the two filaments to which they are bound. The interaction has important implications for the synthesis of biopolymer bundles within cells. I model the cross-linkers as existing in two phases: bound to the bundle and free in solution. When the cross-linkers are bound, they behave as a one-dimensional gas of particles interacting with the Casimir force, while the free phase is a simple ideal gas. Demanding equilibrium between the two phases, I find a discontinuous transition between a sparsely and a densely bound bundle. This discontinuous condensation transition induced by the long-ranged nature of the Casimir interaction allows for a similarly abrupt structural transition in semiflexible filament networks between a low cross linker density isotropic phase and a higher cross link density bundle network. This work is supported by the results of finite element Brownian dynamics simulations of semiflexible filaments and transient cross-linkers. I
Controllable effects of quantum fluctuations on spin free-induction decay at room temperature
Liu, Gang-Qin; Pan, Xin-Yu; Jiang, Zhan-Feng; Zhao, Nan; Liu, Ren-Bao
2012-01-01
Fluctuations of local fields cause decoherence of quantum objects. Usually at high temperatures, thermal noises are much stronger than quantum fluctuations unless the thermal effects are suppressed by certain techniques such as spin echo. Here we report the discovery of strong quantum-fluctuation effects of nuclear spin baths on free-induction decay of single electron spins in solids at room temperature. We find that the competition between the quantum and thermal fluctuations is controllable by an external magnetic field. These findings are based on Ramsey interference measurement of single nitrogen-vacancy center spins in diamond and numerical simulation of the decoherence, which are in excellent agreement. PMID:22666535
Thomas, Siby; Ajith, K. M.; Valsakumar, M. C.
2017-11-01
This work intents to put forth the results of a classical molecular dynamics study to investigate the temperature dependent elastic constants of monolayer hexagonal boron nitride (h-BN) between 100 and 1000 K for the first time using strain fluctuation method. The temperature dependence of out-of-plane fluctuations (ripples) is quantified and is explained using continuum theory of membranes. At low temperatures, negative in-plane thermal expansion is observed and at high temperatures, a transition to positive thermal expansion has been observed due to the presence of thermally excited ripples. The decrease of Young's modulus, bulk modulus, shear modulus and Poisson's ratio with increase in temperature has been analyzed. The thermal rippling in h-BN leads to strong anharmonic behaviour that causes large deviation from the isotropic elasticity. A detailed study shows that the strong thermal rippling in large systems is also responsible for the softening of elastic constants in h-BN. From the determined values of elastic constants and elastic moduli, it has been elucidated that 2D h-BN sheets meet the Born's mechanical stability criterion in the investigated temperature range. The variation of longitudinal and shear velocities with temperature is also calculated from the computed values of elastic constants and elastic moduli.
Force fluctuations and polymerization dynamics of intracellular microtubules
Brangwynne, Clifford
2008-03-01
Microtubules are dynamic biopolymers within the cytoskeleton of living cells. They play a central role in many biological processes including cell division, migration, and cargo transport. Microtubules are significantly more rigid than other cytoskeletal biopolymers, such as actin filaments, and are insensitive to thermal fluctuations on cellular length scales. However, we show that intracellular microtubules exhibit bending amplitudes with a surprisingly thermal-like wavevector dependence, but with an apparent persistence length about 100 times smaller than that measured in vitro. By studying the time-dependent bending fluctuations of individual filaments, we find that the thermal-like bends are fluctuating significantly only on short length scales, while they are frozen-in on longer length scales [1], reminiscent of non-ergodic behavior seen in systems far from equilibrium. Long wavelength bends are suppressed by the surrounding elastic cytoskeleton, which confines bending to short length scales on the order of a few microns [2]. These short wavelength bending fluctuations naturally cause fluctuations in the orientation of the microtubule tip. Tip fluctuations result in a persistent random walk trajectory of microtubule growth, but with a small non-equilibrium persistence length, explaining the origin of quenched thermal-like bends. These results suggest that intracellular motor activity has a highly fluctuating character that dominates over thermal fluctuations, with important consequences for fundamental biological processes. [1] CP Brangwynne, FC MacKintosh, DA Weitz, PNAS, 104:16128 (2007). [2] CP Brangwynne, FC MacKintosh, S Kumar, NA Geisse, J Talbot, L. Mahadevan, KK Parker, DE Ingber, DA Weitz, JCB, 173:733 (2006).
Directory of Open Access Journals (Sweden)
P. P. Paskov
2017-09-01
Full Text Available The effect of Si doping on the thermal conductivity of bulk GaN was studied both theoretically and experimentally. The thermal conductivity of samples grown by Hydride Phase Vapor Epitaxy (HVPE with Si concentration ranging from 1.6×1016 to 7×1018 cm-3 was measured at room temperature and above using the 3ω method. The room temperature thermal conductivity was found to decrease with increasing Si concentration. The highest value of 245±5 W/m.K measured for the undoped sample was consistent with the previously reported data for free-standing HVPE grown GaN. In all samples, the thermal conductivity decreased with increasing temperature. In our previous study, we found that the slope of the temperature dependence of the thermal conductivity gradually decreased with increasing Si doping. Additionally, at temperatures above 350 K the thermal conductivity in the highest doped sample (7×1018 cm-3 was higher than that of lower doped samples. In this work, a modified Callaway model adopted for n-type GaN at high temperatures was developed in order to explain such unusual behavior. The experimental data was analyzed with examination of the contributions of all relevant phonon scattering processes. A reasonable match between the measured and theoretically predicted thermal conductivity was obtained. It was found that in n-type GaN with low dislocation densities the phonon-free-electron scattering becomes an important resistive process at higher temperatures. At the highest free electron concentrations, the electronic thermal conductivity was suggested to play a role in addition to the lattice thermal conductivity and compete with the effect of the phonon-point-defect and phonon-free-electron scattering.
Paskov, P. P.; Slomski, M.; Leach, J. H.; Muth, J. F.; Paskova, T.
2017-09-01
The effect of Si doping on the thermal conductivity of bulk GaN was studied both theoretically and experimentally. The thermal conductivity of samples grown by Hydride Phase Vapor Epitaxy (HVPE) with Si concentration ranging from 1.6×1016 to 7×1018 cm-3 was measured at room temperature and above using the 3ω method. The room temperature thermal conductivity was found to decrease with increasing Si concentration. The highest value of 245±5 W/m.K measured for the undoped sample was consistent with the previously reported data for free-standing HVPE grown GaN. In all samples, the thermal conductivity decreased with increasing temperature. In our previous study, we found that the slope of the temperature dependence of the thermal conductivity gradually decreased with increasing Si doping. Additionally, at temperatures above 350 K the thermal conductivity in the highest doped sample (7×1018 cm-3) was higher than that of lower doped samples. In this work, a modified Callaway model adopted for n-type GaN at high temperatures was developed in order to explain such unusual behavior. The experimental data was analyzed with examination of the contributions of all relevant phonon scattering processes. A reasonable match between the measured and theoretically predicted thermal conductivity was obtained. It was found that in n-type GaN with low dislocation densities the phonon-free-electron scattering becomes an important resistive process at higher temperatures. At the highest free electron concentrations, the electronic thermal conductivity was suggested to play a role in addition to the lattice thermal conductivity and compete with the effect of the phonon-point-defect and phonon-free-electron scattering.
Microcanonical quantum fluctuation theorems.
Talkner, Peter; Hänggi, Peter; Morillo, Manuel
2008-05-01
Previously derived expressions for the characteristic function of work performed on a quantum system by a classical external force are generalized to arbitrary initial states of the considered system and to Hamiltonians with degenerate spectra. In the particular case of microcanonical initial states, explicit expressions for the characteristic function and the corresponding probability density of work are formulated. Their classical limit as well as their relations to the corresponding canonical expressions are discussed. A fluctuation theorem is derived that expresses the ratio of probabilities of work for a process and its time reversal to the ratio of densities of states of the microcanonical equilibrium systems with corresponding initial and final Hamiltonians. From this Crooks-type fluctuation theorem a relation between entropies of different systems can be derived which does not involve the time-reversed process. This entropy-from-work theorem provides an experimentally accessible way to measure entropies.
Energy Technology Data Exchange (ETDEWEB)
Alvarez Rivas, J. L.
1963-07-01
The distribution of thermal neutron flux has been measured inside and outside copper rods of several diameters, immersed in water. It has been found that these distributions can be calculated by means of elemental diffusion theory if the value of the coefficient of diffusion is changed. this parameter is truly a diffusion coefficient, which now also depends on the diameter of the rod. Through a model an expression of this coefficient is introduced which takes account of the measurements of the author and of those reported in PUGC P/928 (1995), ANL-5872 (1959), DEGR 319 (D) (1961). This model could be extended also to plane geometry. (Author) 19 refs.
Nonequilibrium potential and fluctuation theorems for quantum maps.
Manzano, Gonzalo; Horowitz, Jordan M; Parrondo, Juan M R
2015-09-01
We derive a general fluctuation theorem for quantum maps. The theorem applies to a broad class of quantum dynamics, such as unitary evolution, decoherence, thermalization, and other types of evolution for quantum open systems. The theorem reproduces well-known fluctuation theorems in a single and simplified framework and extends the Hatano-Sasa theorem to quantum nonequilibrium processes. Moreover, it helps to elucidate the physical nature of the environment that induces a given dynamics in an open quantum system.
Goldman, Benjamin D.; Dowell, Earl H.; Scott, Robert C.
2015-01-01
Conical shell theory and a supersonic potential flow aerodynamic theory are used to study the nonlinear pressure buckling and aeroelastic limit cycle behavior of the thermal protection system for NASA's Hypersonic Inflatable Aerodynamic Decelerator. The structural model of the thermal protection system consists of an orthotropic conical shell of the Donnell type, resting on several circumferential elastic supports. Classical Piston Theory is used initially for the aerodynamic pressure, but was found to be insufficient at low supersonic Mach numbers. Transform methods are applied to the convected wave equation for potential flow, and a time-dependent aerodynamic pressure correction factor is obtained. The Lagrangian of the shell system is formulated in terms of the generalized coordinates for all displacements and the Rayleigh-Ritz method is used to derive the governing differential-algebraic equations of motion. Aeroelastic limit cycle oscillations and buckling deformations are calculated in the time domain using a Runge-Kutta method in MATLAB. Three conical shell geometries were considered in the present analysis: a 3-meter diameter 70 deg. cone, a 3.7-meter 70 deg. cone, and a 6-meter diameter 70 deg. cone. The 6-meter configuration was loaded statically and the results were compared with an experimental load test of a 6-meter HIAD. Though agreement between theoretical and experimental strains was poor, the circumferential wrinkling phenomena observed during the experiments was captured by the theory and axial deformations were qualitatively similar in shape. With Piston Theory aerodynamics, the nonlinear flutter dynamic pressures of the 3-meter configuration were in agreement with the values calculated using linear theory, and the limit cycle amplitudes were generally on the order of the shell thickness. The effect of axial tension was studied for this configuration, and increasing tension was found to decrease the limit cycle amplitudes when the circumferential
Critical geometry of a thermal big bang
Afshordi, Niayesh; Magueijo, João
2016-11-01
We explore the space of scalar-tensor theories containing two nonconformal metrics, and find a discontinuity pointing to a "critical" cosmological solution. Due to the different maximal speeds of propagation for matter and gravity, the cosmological fluctuations start off inside the horizon even without inflation, and will more naturally have a thermal origin (since there is never vacuum domination). The critical model makes an unambiguous, nontuned prediction for the spectral index of the scalar fluctuations: nS=0.96478 (64 ) . Considering also that no gravitational waves are produced, we have unveiled the most predictive model on offer. The model has a simple geometrical interpretation as a probe 3-brane embedded in an E AdS2×E3 geometry.
Universal fluctuations the phenomenology of hadronic matter
Botet, Robert
2002-01-01
The main purpose of this book is to present, in a comprehensive and progressive way, the appearance of universal limit probability laws in physics, and their connection with the recently developed scaling theory of fluctuations. Arising from the probability theory and renormalization group methods, this novel approach has been proved recently to provide efficient investigative tools for the collective features that occur in any finite system. The mathematical background is self-contained and is formulated in terms which are easy to apply to the physical context. After illustrating the problem
Low Mach number fluctuating hydrodynamics for electrolytes
Péraud, Jean-Philippe; Nonaka, Andy; Chaudhri, Anuj; Bell, John B.; Donev, Aleksandar; Garcia, Alejandro L.
2016-11-01
We formulate and study computationally the low Mach number fluctuating hydrodynamic equations for electrolyte solutions. We are interested in studying transport in mixtures of charged species at the mesoscale, down to scales below the Debye length, where thermal fluctuations have a significant impact on the dynamics. Continuing our previous work on fluctuating hydrodynamics of multicomponent mixtures of incompressible isothermal miscible liquids [A. Donev et al., Phys. Fluids 27, 037103 (2015), 10.1063/1.4913571], we now include the effect of charged species using a quasielectrostatic approximation. Localized charges create an electric field, which in turn provides additional forcing in the mass and momentum equations. Our low Mach number formulation eliminates sound waves from the fully compressible formulation and leads to a more computationally efficient quasi-incompressible formulation. We demonstrate our ability to model saltwater (NaCl) solutions in both equilibrium and nonequilibrium settings. We show that our algorithm is second order in the deterministic setting and for length scales much greater than the Debye length gives results consistent with an electroneutral approximation. In the stochastic setting, our model captures the predicted dynamics of equilibrium and nonequilibrium fluctuations. We also identify and model an instability that appears when diffusive mixing occurs in the presence of an applied electric field.
Trapped Electron Precession Shear Induced Fluctuation Decorrelation
Energy Technology Data Exchange (ETDEWEB)
T.S. Hahm; P.H. Diamond; E.-J. Kim
2002-07-29
We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.
Vinogradov, A. P.; Burokur, N.; Zouhdi, S.
2009-01-01
Abstract It is shown that the space fluctuations of concentration of conducting inclusions might be responsible for the well-known disagreement between theory and experiment at determining microwave losses in metal-dielectric mixture: the theories (percolation theory, effective medium theory, etc.) predict much lower losses than those measured in experiment. It is demonstrated that if the effective skin depth in the regions occupied by the fluctuation is com...
Fluctuation relations for anisotropic systems
Villavicencio-Sanchez, R.; Harris, R. J.; Touchette, H.
2014-02-01
Currents of particles or energy in driven non-equilibrium steady states are known to satisfy certain symmetries, referred to as fluctuation relations, determining the ratio of the probabilities of positive fluctuations to negative ones. A generalization of these fluctuation relations has been proposed recently for extended non-equilibrium systems of dimension greater than one, assuming, crucially, that they are isotropic (Hurtado P. I., Pérez-Espigares C., del Pozo J. J. and Garrido P. L., Proc. Natl. Acad. Sci. U.S.A., 108 (2011) 7704). Here we relax this assumption and derive a fluctuation relation for d-dimensional systems having anisotropic bulk driving rates. We test the validity of this anisotropic fluctuation relation by calculating the particle current fluctuations in the 2d anisotropic zero-range process, using both exact and fluctuating hydrodynamic approaches.
Motion of Euglena gracilis: Active fluctuations and velocity distribution
Romanczuk, P.; Romensky, M.; Scholz, D.; Lobaskin, V.; Schimansky-Geier, L.
2015-07-01
We study the velocity distribution of unicellular swimming algae Euglena gracilis using optical microscopy and active Brownian particle theory. To characterize a peculiar feature of the experimentally observed distribution at small velocities we use the concept of active fluctuations, which was recently proposed for the description of stochastically self-propelled particles [Romanczuk, P. and Schimansky-Geier, L., Phys. Rev. Lett. 106, 230601 (2011)]. In this concept, the fluctuating forces arise due to internal random performance of the propulsive motor. The fluctuating forces are directed in parallel to the heading direction, in which the propulsion acts. In the theory, we introduce the active motion via the depot model [Schweitzer, et al., Phys. Rev. Lett. 80(23), 5044 (1998)]. We demonstrate that the theoretical predictions based on the depot model with active fluctuations are consistent with the experimentally observed velocity distributions. In addition to the model with additive active noise, we obtain theoretical results for a constant propulsion with multiplicative noise.
Energy Technology Data Exchange (ETDEWEB)
Hanson, R.G.; Johnson, E.C. [eds.; Carlson, K.E.; Riemke, R.A.; Wagner, R.J.
1992-07-01
This report documents the theory and input requirements for the multidimensional component in RELAP5/MOD2.5, Version 3w. The equations in Cartesian and cylindrical coordinates are presented as well as the shallow water terms. The implementation of these equations is then discussed. Finally, the constitutive models and input requirements are then described.
Pal, Pinaki
2016-07-27
Auto-ignition characteristics of compositionally homogeneous reactant mixtures in the presence of thermal non-uniformities and turbulent velocity fluctuations were computationally investigated. The main objectives were to quantify the observed ignition characteristics and numerically validate the theory of the turbulent ignition regime diagram recently proposed by Im et al. 2015 [29] that provides a framework to predict ignition behavior . a priori based on the thermo-chemical properties of the reactant mixture and initial flow and scalar field conditions. Ignition regimes were classified into three categories: . weak (where deflagration is the dominant mode of fuel consumption), . reaction-dominant strong, and . mixing-dominant strong (where volumetric ignition is the dominant mode of fuel consumption). Two-dimensional (2D) direct numerical simulations (DNS) of auto-ignition in a lean syngas/air mixture with uniform mixture composition at high-pressure, low-temperature conditions were performed in a fixed volume. The initial conditions considered two-dimensional isotropic velocity spectrums, temperature fluctuations and localized thermal hot spots. A number of parametric test cases, by varying the characteristic turbulent Damköhler and Reynolds numbers, were investigated. The evolution of the auto-ignition phenomena, pressure rise, and heat release rate were analyzed. In addition, combustion mode analysis based on front propagation speed and computational singular perturbation (CSP) was applied to characterize the auto-ignition phenomena. All results supported that the observed ignition behaviors were consistent with the expected ignition regimes predicted by the theory of the regime diagram. This work provides new high-fidelity data on syngas ignition characteristics over a broad range of conditions and demonstrates that the regime diagram serves as a predictive guidance in the understanding of various physical and chemical mechanisms controlling auto
Fundamental Bounds on First Passage Time Fluctuations for Currents
Gingrich, Todd R.; Horowitz, Jordan M.
2017-10-01
Current is a characteristic feature of nonequilibrium systems. In stochastic systems, these currents exhibit fluctuations constrained by the rate of dissipation in accordance with the recently discovered thermodynamic uncertainty relation. Here, we derive a conjugate uncertainty relationship for the first passage time to accumulate a fixed net current. More generally, we use the tools of large-deviation theory to simply connect current fluctuations and first passage time fluctuations in the limit of long times and large currents. With this connection, previously discovered symmetries and bounds on the large-deviation function for currents are readily transferred to first passage times.
Effective field theory of dissipative fluids
Crossley, Michael; Glorioso, Paolo; Liu, Hong
2017-09-01
We develop an effective field theory for dissipative fluids which governs the dynamics of long-lived gapless modes associated with conserved quantities. The resulting theory gives a path integral formulation of fluctuating hydrodynamics which systematically incorporates nonlinear interactions of noises. The dynamical variables are mappings between a "fluid spacetime" and the physical spacetime and an essential aspect of our formulation is to identify the appropriate symmetries in the fluid spacetime. The theory applies to nonlinear disturbances around a general density matrix. For a thermal density matrix, we require an additional Z 2 symmetry, to which we refer as the local KMS condition. This leads to the standard constraints of hydrodynamics, as well as a nonlinear generalization of the Onsager relations. It also leads to an emergent supersymmetry in the classical statistical regime, and a higher derivative deformation of supersymmetry in the full quantum regime.
Fluctuation of the electric field in a plasma
Lee, Hee J.
2015-04-01
The theory of electric field fluctuations in a plasma is reviewed. The fluctuations of an electric field can be assumed to be due to the Cerenkov radiation, which is emitted by single particles that satisfy the Landau wave-particle resonance conditions. This view naturally agrees with the picture that a plasma can be considered to be an aggregate of non-interacting dressed particles. A simple classical derivation of the fluctuation-dissipation theorem is presented to show that the fluctuations of the Cerenkov electric field agree with the fluctuation-dissipation theorem. A quasilinear-like solution of the Liouville equation is shown to derive an electric field fluctuation with the same form as that obtained by using the dressed particle approach. We suggest that the fluctuation can be traced to the causality that gives rise to collisionless dissipation (imaginary part of the dielectric function). Therefore, the fluctuation in a plasma has a philosophical implication in that its existence is fundamentally due to the causal principle that the effect cannot be precedent to the cause, thus defining the direction of time.
Market Mechanism Design for Renewable Energy based on Risk Theory
Yang, Wu; Bo, Wang; Jichun, Liu; Wenjiao, Zai; Pingliang, Zeng; Haobo, Shi
2018-02-01
Generation trading between renewable energy and thermal power is an efficient market means for transforming supply structure of electric power into sustainable development pattern. But the trading is hampered by the output fluctuations of renewable energy and the cost differences between renewable energy and thermal power at present. In this paper, the external environmental cost (EEC) is defined and the EEC is introduced into the generation cost. At same time, the incentive functions of renewable energy and low-emission thermal power are designed, which are decreasing functions of EEC. On these bases, for the market risks caused by the random variability of EEC, the decision-making model of generation trading between renewable energy and thermal power is constructed according to the risk theory. The feasibility and effectiveness of the proposed model are verified by simulation results.
Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited
DEFF Research Database (Denmark)
Miao, L.; Lomholt, Michael Andersen; Kleis, J.
2002-01-01
of the phenomenological constants in a canonical continuum description of fluid lipid-bilayer membranes and shown the consequences of this new interpretation in terms of the characteristics of the dynamics of vesicle shape fluctuations. Moreover, we have used the systematic formulation of our theory as a framework...... against which we have discussed the previously existing theories and their discrepancies. Finally, we have made a systematic prediction about the system-dependent characteristics of the relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a view of experimental studies......In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations...
Krüger, Dennis M; Rathi, Prakash Chandra; Pfleger, Christopher; Gohlke, Holger
2013-07-01
The Constraint Network Analysis (CNA) web server provides a user-friendly interface to the CNA approach developed in our laboratory for linking results from rigidity analyses to biologically relevant characteristics of a biomolecular structure. The CNA web server provides a refined modeling of thermal unfolding simulations that considers the temperature dependence of hydrophobic tethers and computes a set of global and local indices for quantifying biomacromolecular stability. From the global indices, phase transition points are identified where the structure switches from a rigid to a floppy state; these phase transition points can be related to a protein's (thermo-)stability. Structural weak spots (unfolding nuclei) are automatically identified, too; this knowledge can be exploited in data-driven protein engineering. The local indices are useful in linking flexibility and function and to understand the impact of ligand binding on protein flexibility. The CNA web server robustly handles small-molecule ligands in general. To overcome issues of sensitivity with respect to the input structure, the CNA web server allows performing two ensemble-based variants of thermal unfolding simulations. The web server output is provided as raw data, plots and/or Jmol representations. The CNA web server, accessible at http://cpclab.uni-duesseldorf.de/cna or http://www.cnanalysis.de, is free and open to all users with no login requirement.
Hydrodynamic fluctuations, long-time tails, and supersymmetry
Kovtun, Pavel; Yaffe, Laurence G.
2003-07-01
Hydrodynamic fluctuations at a nonzero temperature can cause slow relaxation toward equilibrium even in observables which are not locally conserved. A classic example is the stress-stress correlator in a normal fluid, which, at zero wave number, behaves at large times as t-3/2. A novel feature of the effective theory of hydrodynamic fluctuations in supersymmetric theories is the presence of Grassmann-valued classical fields describing macroscopic supercharge density fluctuations. We show that hydrodynamic fluctuations in supersymmetric theories generate essentially the same long-time power-law tails in real-time correlation functions that are known in simple fluids. In particular, a t-3/2 long-time tail must exist in the stress-stress correlator of N=4 supersymmetric Yang-Mills theory at non-zero temperature, regardless of the value of the coupling. Consequently, this feature of finite-temperature dynamics can provide an interesting test of the AdS/CFT correspondence. However, the coefficient of this long-time tail is suppressed by a factor of 1/N2c. On the gravitational side, this implies that these long-time tails are not present in the classical supergravity limit; they must instead be produced by one-loop gravitational fluctuations.
Effect of quantum fluctuation in error-correcting codes.
Otsubo, Yosuke; Inoue, Jun-ichi; Nagata, Kenji; Okada, Masato
2012-11-01
We discuss the decoding performance of error-correcting codes based on a model in which quantum fluctuations are introduced by means of a transverse field. The essential issue in this paper is whether quantum fluctuations improve the decoding quality compared with the conventional estimation based on thermal fluctuations, which is called finite-temperature decoding. We found that an estimation incorporating quantum fluctuations approaches the optimal performance of finite-temperature decoding. The results are illustrated by numerically solving saddle-point equations and performing a Monte Carlo simulation. We also evaluated the upper bound of the overlap between the original sequence and the decoded sequence derived from the equations of state for the order parameters, which is a measure of the decoding performance.
Fluctuation theorems and orbital magnetism in nonequilibrium state
Indian Academy of Sciences (India)
rare and are related to transient second law violating contributions. These theo- rems are useful to probe nonequilibrium states in nanophysics and biology. In these systems energies involved are typically small and hence thermal fluctuations play a significant role. In fact, variance in some of the physical quantities dominate.
Growth and decay of large fluctuations far from equilibrium
Indian Academy of Sciences (India)
Home; Journals; Journal of Chemical Sciences; Volume 121; Issue 5 ... interesting `detailed balance' like condition in the steady state which is manifested in the time reversal symmetry between growth and decay of fluctuation far from equilibrium, similar to what is observed in thermally equilibrated systems, is demonstrated.
Statistical fluctuations and correlations in hadronic equilibrium systems
Energy Technology Data Exchange (ETDEWEB)
Hauer, Michael
2010-06-17
This thesis is dedicated to the study of fluctuation and correlation observables of hadronic equilibrium systems. The statistical hadronization model of high energy physics, in its ideal, i.e. non-interacting, gas approximation is investigated in different ensemble formulations. The hypothesis of thermal and chemical equilibrium in high energy interaction is tested against qualitative and quantitative predictions. (orig.)
Growth and decay of large fluctuations far from equilibrium
Indian Academy of Sciences (India)
Administrator
phase transition, glycolytic oscillations, etc. The principle of detailed balance takes care of, on an average, a balance of input of energy into the system through thermal fluctuation and output of energy from the system due to dissipation in a thermody- namically closed system. Can such a detailed bal- ance like condition be ...
Fundamentals of Thermal Expansion and Thermal Contraction
Liu, Zi-Kui; Shang, Shun-Li; Wang, Yi
2017-01-01
Thermal expansion is an important property of substances. Its theoretical prediction has been challenging, particularly in cases the volume decreases with temperature, i.e., thermal contraction or negative thermal expansion at high temperatures. In this paper, a new theory recently developed by the authors has been reviewed and further examined in the framework of fundamental thermodynamics and statistical mechanics. Its applications to cerium with colossal thermal expansion and Fe3Pt with th...
Balasubramanian, V.; Bernamonti, A.; de Boer, J.; Copland, N.; Craps, B.; Keski-Vakkuri, E.; Müller, B.; Schäfer, A.; Shigemori, M.; Staessens, W.
2011-01-01
Using the AdS/CFT correspondence, we probe the scale-dependence of thermalization in strongly coupled field theories following a quench, via calculations of two-point functions, Wilson loops and entanglement entropy in d=2,3,4. In the saddlepoint approximation these probes are computed in AdS space
Zhen, Yaxin; Zhou, Lin
2017-03-01
Based on nonlocal strain gradient theory, wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes (SWCNTs) is studied in this paper. With consideration of thermal effect and surface effect, wave equation is derived for fluid-conveying viscoelastic SWCNTs under longitudinal magnetic field utilizing Euler-Bernoulli beam theory. The closed-form expressions are derived for the frequency and phase velocity of the wave motion. The influences of fluid flow velocity, structural damping coefficient, temperature change, magnetic flux and surface effect are discussed in detail. SWCNTs’ viscoelasticity reduces the wave frequency of the system and the influence gets remarkable with the increase of wave number. The fluid in SWCNTs decreases the frequency of wave propagation to a certain extent. The frequency (phase velocity) gets larger due to the existence of surface effect, especially when the diameters of SWCNTs and the wave number decrease. The wave frequency increases with the increase of the longitudinal magnetic field, while decreases with the increase of the temperature change. The results may be helpful for better understanding the potential applications of SWCNTs in nanotechnology.
Biomolecules: Fluctuations and relaxations
Parak, F.; Ostermann, A.; Gassmann, A.; Scherk, C.; Chong, S.-H.; Kidera, A.; Go, N.
1999-10-01
The normal-mode refinement of X-ray crystallographic data opened a new possibility to analyze the mean-square displacements in a protein molecule. A comparison of the X-ray structure of myoglobin at several temperatures with Mössbauer data is performed. In the low-temperature regime below 180 K the iron mean-square displacements obtained by Mössbauer spectroscopy are in good agreement with a normal-mode analysis. The X-ray mean-square displacements at the position of the iron, after the motion originated from the external degrees of freedom are subtracted, have practically the same temperature dependence as those from Mössbauer spectroscopy. The difference between the X-ray mean-square displacements and those predicted by normal-mode analysis measures the distribution of molecules into conformational substates. Above 180 K the Mössbauer effect indicates fluctuations between conformational substates. The relaxation from a Fe(III) conformation to a Fe(II) conformation is shown for superoxide dismutase of Propionibacterium shermanii.
Fluctuating attention in Parkinson's disease
DEFF Research Database (Denmark)
Starrfelt, Randi; Aarsland, Dag; Janvin, Carmen
2001-01-01
Lewy body dementia (DLB), which share many clinical and pathological features with Parkinson’s disease (PD), is charac- terised by marked fluctuations in cognition and consciousness. Fluctuating cognition has not been formally studied in PD, although some studies indicate that PD patients show...
Quantum Correction of Fluctuation Theorem
Monnai, T.; Tasaki, S.
2003-01-01
Quantum analogues of the transient fluctuation theorem(TFT) and steady-state fluctuation theorem(SSFT) are investigated for a harmonic oscillator linearly coupled with a harmonic reservoir. The probability distribution for the work done externally is derived and quantum correction for TFT and SSFT are calculated.
Pressure Fluctuations in Nonideal Plasma
Lankin, A.; Norman, G.; Saitov, I.
Fluctuations of pressure of singly ionized nonideal plasma are studied using the fluctuation approach which provides the self-consistent joint description of free and weakly bound electron states. The classical molecular dynamics method is used. The electron-ion interaction is described by the
Chaotic Maps Dynamics, Fractals, and Rapid Fluctuations
Chen, Goong
2011-01-01
This book consists of lecture notes for a semester-long introductory graduate course on dynamical systems and chaos taught by the authors at Texas A&M University and Zhongshan University, China. There are ten chapters in the main body of the book, covering an elementary theory of chaotic maps in finite-dimensional spaces. The topics include one-dimensional dynamical systems (interval maps), bifurcations, general topological, symbolic dynamical systems, fractals and a class of infinite-dimensional dynamical systems which are induced by interval maps, plus rapid fluctuations of chaotic maps as a
Nonmotor Fluctuations in Parkinson's Disease.
Franke, Christiana; Storch, Alexander
2017-01-01
The advanced stage of Parkinson's disease (PD) is characterized by motor complications such as motor fluctuations and dyskinesias induced by long-term levodopa treatment. Recent clinical research provides growing evidence that various nonmotor symptoms such as neuropsychiatric, autonomic, and sensory symptoms (particularly pain) also show fluctuations in patients with motor fluctuations (called nonmotor fluctuations or NMF). However, NMF have not yet been adequately considered in routine care of advanced PD patients and only few therapeutic studies are available. Since the pathophysiology of NMF remains largely unknown, innovative therapeutic concepts are largely missing. The close connection of NMF and motor fluctuations, however, strongly suggests that the strategies used to treat motor complications-namely continuous dopaminergic stimulation-also apply for the therapy of NMF. Future controlled clinical trials specifically addressing NMF are urgently warranted. © 2017 Elsevier Inc. All rights reserved.
Staggered Schemes for Fluctuating Hydrodynamics
Balboa, F; Delgado-Buscalioni, R; Donev, A; Fai, T; Griffith, B; Peskin, C S
2011-01-01
We develop numerical schemes for solving the isothermal compressible and incompressible equations of fluctuating hydrodynamics on a grid with staggered momenta. We develop a second-order accurate spatial discretization of the diffusive, advective and stochastic fluxes that satisfies a discrete fluctuation-dissipation balance, and construct temporal discretizations that are at least second-order accurate in time deterministically and in a weak sense. Specifically, the methods reproduce the correct equilibrium covariances of the fluctuating fields to third (compressible) and second (incompressible) order in the time step, as we verify numerically. We apply our techniques to model recent experimental measurements of giant fluctuations in diffusively mixing fluids in a micro-gravity environment [A. Vailati et. al., Nature Communications 2:290, 2011]. Numerical results for the static spectrum of non-equilibrium concentration fluctuations are in excellent agreement between the compressible and incompressible simula...
Fluctuations in catalytic surface reactions
Imbihl, R
2003-01-01
The internal reaction-induced fluctuations which occur in catalytic CO oxidation on a Pt field emitter tip have been studied using field electron microscopy (FEM) as a spatially resolving method. The structurally heterogeneous Pt tip consists of facets of different orientations with nanoscale dimensions. The FEM resolution of roughly 2 nm corresponds to a few hundred reacting adsorbed particles whose variations in the density are imaged as brightness fluctuations. In the bistable range of the reaction one finds fluctuation-induced transitions between the two stable branches of the reaction kinetics. The fluctuations exhibit a behaviour similar to that of an equilibrium phase transition, i.e. the amplitude diverges upon approaching the bifurcation point terminating the bistable range of the reaction. Simulations with a hybrid Monte Carlo/mean-field model reproduce the experimental observations. Fluctuations on different facets are typically uncorrelated but within a single facet a high degree of spatial cohere...
Intrinsic autocorrelation time of picoseconds for thermal noise in water.
Zhu, Zhi; Sheng, Nan; Wan, Rongzheng; Fang, Haiping
2014-10-02
Whether thermal noise is colored or white is of fundamental importance. In conventional theory, thermal noise is usually treated as white noise so that there are no directional transportations in the asymmetrical systems without external inputs, since only the colored fluctuations with appropriate autocorrelation time length can lead to directional transportations in the asymmetrical systems. Here, on the basis of molecular dynamics simulations, we show that the autocorrelation time length of thermal noise in water is ~10 ps at room temperature, which indicates that thermal noise is not white in the molecular scale while thermal noise can be reasonably assumed as white in macro- and meso-scale systems. The autocorrelation time length of thermal noise is intrinsic, since the value is almost unchanged for different temperature coupling methods. Interestingly, the autocorrelation time of thermal noise is correlated with the lifetime of hydrogen bonds, suggesting that the finite autocorrelation time length of thermal noise mainly comes from the finite lifetime of the interactions between neighboring water molecules.
Determination of freeze-out conditions from fluctuation observables measured at RHIC
Energy Technology Data Exchange (ETDEWEB)
Bluhm, M. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Alba, P.; Alberico, W. [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Bellwied, R. [Department of Physics, University of Houston, Houston, TX 77204 (United States); Mantovani Sarti, V. [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Nahrgang, M. [Department of Physics, Duke University, Durham, NC 27708 (United States); Ratti, C. [Department of Physics, Torino University and INFN, Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy)
2014-11-15
We extract chemical freeze-out conditions via a thermal model approach from fluctuation observables measured at RHIC and compare with results from lattice QCD and statistical hadronization model fits. The possible influence of additional critical and non-critical fluctuation sources not accounted for in our analysis is discussed.
Stepanov, A. V.
2015-11-01
Activation process for unimolecular reaction has been considered by means of radiation theory. The formulae of information entropy of activation have been derived for the Boltzmann-Arrhenius model and the activation process model (APM). The physical meaning of this entropy has been determined. It is a measure of conversion of thermal radiation energy to mechanical energy that moves atoms in a molecule during elementary activation act. It is also a measure of uncertainty of this energy conversion. The uncertainty is due to unevenness of distribution function representing the activation process. It has been shown that Arrhenius dependence is caused by the entropy change. Efficiency comparison of the two models under consideration for low-temperature fluctuations of a myoglobin molecule structure shows that the APM should be favored over the Boltzmann-Arrhenius one.
Cross-correlation of output fluctuation and system-balancing cost in photovoltaic integration
Directory of Open Access Journals (Sweden)
Yuichi Ikeda
2014-10-01
Full Text Available The authors analysed the cross-correlation of photovoltaic (PV output fluctuation for the actual PV output time series data in both the Tokyo area and the whole of Japan using the principal component analysis with the random matrix theory. Based on the obtained cross-correlation coefficients, the forecast error for PV output was estimated with/without considering the cross-correlations. Then the operation schedule of thermal plants is calculated to integrate PV output using the proposed unit commitment model with the estimated forecast error. The system-balancing cost of PV system was also estimated with or without demand response. Finally, validity of the concept of ‘local production for local consumption of renewable energy’ and alternative policy implications were discussed.
The role played by thermal feedback in heated Farley-Buneman waves at high latitudes
Directory of Open Access Journals (Sweden)
J.-P. St.-Maurice
Full Text Available It is becoming increasingly clear that electron thermal effects have to be taken into account when dealing with the theory of ionospheric instabilities in the high-latitude ionosphere. Unfortunately, the mathematical complexity often hides the physical processes at work. We follow the limiting cases of a complex but systematic generalized fluid approach to get to the heart of the thermal processes that affect the stability of E region waves during electron heating events. We try to show as simply as possible under what conditions thermal effects contribute to the destabilization of strongly field-aligned (zero aspect angle Farley-Buneman modes. We show that destabilization can arise from a combination of (1 a reduction in pressure gradients associated with temperature fluctuations that are out of phase with density fluctuations, and (2 thermal diffusion, which takes the electrons from regions of enhanced temperatures to regions of negative temperature fluctuations, and therefore enhanced densities. However, we also show that, contrary to what has been suggested in the past, for modes excited along the E_{0}×B direction thermal feedback decreases the growth rate and raises the threshold speed of the Farley-Buneman instability. The increase in threshold speed appears to be important enough to explain the generation of `Type IV' waves in the high-latitude ionosphere.
Key words: Ionosphere (auroral ionosphere; iono- spheric irregularities; plasma waves and instabilities
The role played by thermal feedback in heated Farley-Buneman waves at high latitudes
Directory of Open Access Journals (Sweden)
J.-P. St.-Maurice
2000-05-01
Full Text Available It is becoming increasingly clear that electron thermal effects have to be taken into account when dealing with the theory of ionospheric instabilities in the high-latitude ionosphere. Unfortunately, the mathematical complexity often hides the physical processes at work. We follow the limiting cases of a complex but systematic generalized fluid approach to get to the heart of the thermal processes that affect the stability of E region waves during electron heating events. We try to show as simply as possible under what conditions thermal effects contribute to the destabilization of strongly field-aligned (zero aspect angle Farley-Buneman modes. We show that destabilization can arise from a combination of (1 a reduction in pressure gradients associated with temperature fluctuations that are out of phase with density fluctuations, and (2 thermal diffusion, which takes the electrons from regions of enhanced temperatures to regions of negative temperature fluctuations, and therefore enhanced densities. However, we also show that, contrary to what has been suggested in the past, for modes excited along the E0×B direction thermal feedback decreases the growth rate and raises the threshold speed of the Farley-Buneman instability. The increase in threshold speed appears to be important enough to explain the generation of `Type IV' waves in the high-latitude ionosphere.Key words: Ionosphere (auroral ionosphere; iono- spheric irregularities; plasma waves and instabilities
Dooremalen, van C.; Suring, W.; Ellers, J.
2011-01-01
Ectotherms commonly adjust their lipid composition to ambient temperature to counteract detrimental thermal effects on lipid fluidity. However, the extent of lipid remodeling and the associated fitness consequences under continuous temperature fluctuations are not well-described. The objective of
Stress fluctuations in sheared Stokesian suspensions.
Dasan, J; Ramamohan, T R; Singh, Anugrah; Nott, Prabhu R
2002-08-01
We report an analysis, using the tools of nonlinear dynamics and chaos theory, of the fluctuations in the stress determined from simulations of shear flow of Stokesian suspensions. The simulations are for shear between plane parallel walls of a suspension of rigid identical spheres in a Newtonian fluid, over a range of particle concentration. By analyzing the time series of the stress, we find that the dynamics underlying these fluctuations is deterministic, low-dimensional, and chaotic. We use the dynamic and metric invariants of the underlying dynamics as a means of characterizing suspension behavior. The dimension of the chaotic attractor increases with particle concentration, indicating the increasing influence of multiple-body interactions on the rheology of the suspension with rise in particle concentration. We use our analysis to make accurate predictions of the short-term evolution of a stress component from its preceding time series, and predict the evolution of one component of the stress using the time series of another. We comment on the physical origin of the chaotic stress fluctuations, and on the implications of our results on the relation between the microstructure and the stress.
Fluctuation-dissipation relation in a resonantly driven quantum medium.
Erukhimova, Maria; Tokman, Mikhail
2015-06-15
Noise associated with the spontaneous emission in a coherently driven medium is calculated. The significant field-induced modification of relation between the noise power and damping constant in a thermal reservoir is obtained. The nonlinear noise exchange between different atomic frequencies leads to violation of standard relations dictated by the fluctuation-dissipation theorem. The developed general method is applied to the EIT system, attractive for realization of different quantum-information processing devices. It is shown that there is a significant factor defining the thermal noise at operating frequency in the EIT system. It is the averaged number of thermal photons at low frequency of ground state splitting.
Fluctuation sensitivity of a transcriptional signaling cascade
Pilkiewicz, Kevin R.; Mayo, Michael L.
2016-09-01
The internal biochemical state of a cell is regulated by a vast transcriptional network that kinetically correlates the concentrations of numerous proteins. Fluctuations in protein concentration that encode crucial information about this changing state must compete with fluctuations caused by the noisy cellular environment in order to successfully transmit information across the network. Oftentimes, one protein must regulate another through a sequence of intermediaries, and conventional wisdom, derived from the data processing inequality of information theory, leads us to expect that longer sequences should lose more information to noise. Using the metric of mutual information to characterize the fluctuation sensitivity of transcriptional signaling cascades, we find, counter to this expectation, that longer chains of regulatory interactions can instead lead to enhanced informational efficiency. We derive an analytic expression for the mutual information from a generalized chemical kinetics model that we reduce to simple, mass-action kinetics by linearizing for small fluctuations about the basal biological steady state, and we find that at long times this expression depends only on a simple ratio of protein production to destruction rates and the length of the cascade. We place bounds on the values of these parameters by requiring that the mutual information be at least one bit—otherwise, any received signal would be indistinguishable from noise—and we find not only that nature has devised a way to circumvent the data processing inequality, but that it must be circumvented to attain this one-bit threshold. We demonstrate how this result places informational and biochemical efficiency at odds with one another by correlating high transcription factor binding affinities with low informational output, and we conclude with an analysis of the validity of our assumptions and propose how they might be tested experimentally.
Probing thermodynamic fluctuations in high temperature superconductors
Vidal, Felix; Veira, J. A.; Maza, J.; Miguélez, F.; Morán, E.; Alario, M. A.
1988-04-01
We probe thermodynamic fluctuations in HTSC by measuring the excess electrical conductivity, Δσ, abovr T c in single-phase (within 4%) Ba 2LnCu 3O 7-δ compounds, with LnY, Ho and Sm. As expected, the measured relative effect, Δσ / σ (300 K), is much more important in HTSC than for low-temperature superconductors (at least one order of magnitude). In the reduced temperature region -5=-0.47 ± 0.06. This result confirms an universal critical behaviour of Δσ in HTSC, and the value of agrees with that predicted by the Aslamazov-Larkin (AL) theory for three-dimensional BCS superconductivity. However, A shows a normal conductivity dependence which is not accounted for by the AL theory.
Fluctuations and Linear Response in Supercooled Liquids
DEFF Research Database (Denmark)
Nielsen, Johannes K.
of the external thermodynamic system parameters. In thermodynamic response theory equivalence between ensembles is broken, but time correlation functions sampled in different ensembles are connected through the Maxwell relations of thermodynamics generalized to the frequency domain. Different applications......Fluctuation dissipation theorems are derived for thermodynamic properties like frequency dependent specific heat and compressibility. First the case where a systems dynamics are restricted by constant volume and energy is considered. The dynamic linear response to a heat pulse and a volume change...... of the theory in the field of supercooled liquids are showed. First the full frequency dependent thermodynamic response matrix is extracted from simulations of a binary Lennard Jones liquid. Secondly some simple stochastic models of supercooled liquids are analysed in the framework of linear thermodynamic...
Magnetic disorder in superconductors: Enhancement by mesoscopic fluctuations
Burmistrov, I. S.; Skvortsov, M. A.
2018-01-01
We study the density of states (DOS) and the transition temperature Tc in a dirty superconducting film with rare classical magnetic impurities of an arbitrary strength described by the Poissonian statistics. We take into account that the potential disorder is a source of mesoscopic fluctuations of the local DOS, and, consequently, of the effective strength of magnetic impurities. We find that these mesoscopic fluctuations result in a nonzero DOS for all energies in the region of the phase diagram where without this effect the DOS is zero within the standard mean-field theory. This mechanism can be more efficient in filling the mean-field superconducting gap than rare fluctuations of the potential disorder (instantons). Depending on the magnetic impurity strength, the suppression of Tc by spin-flip scattering can be faster or slower than in the standard mean-field theory.
Skewness of elliptic flow fluctuations
Giacalone, Giuliano; Yan, Li; Noronha-Hostler, Jacquelyn; Ollitrault, Jean-Yves
2017-01-01
Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow (v2) in the reaction plane have a negative skew. We compare the skewness of v2 fluctuations to that of initial eccentricity fluctuations. We show that skewness is the main effect lifting the degeneracy between higher-order cumulants, with negative skew corresponding to the hierarchy v2{4 } >v2{6 } observed in Pb+Pb collisions at the CERN Large Hadron Collider. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.
Fluctuation theorem: A critical review
Malek Mansour, M.; Baras, F.
2017-10-01
Fluctuation theorem for entropy production is revisited in the framework of stochastic processes. The applicability of the fluctuation theorem to physico-chemical systems and the resulting stochastic thermodynamics were analyzed. Some unexpected limitations are highlighted in the context of jump Markov processes. We have shown that these limitations handicap the ability of the resulting stochastic thermodynamics to correctly describe the state of non-equilibrium systems in terms of the thermodynamic properties of individual processes therein. Finally, we considered the case of diffusion processes and proved that the fluctuation theorem for entropy production becomes irrelevant at the stationary state in the case of one variable systems.
Density fluctuations in traffic flow
Yukawa, S
1996-01-01
Density fluctuations in traffic current are studied by computer simulations using the deterministic coupled map lattice model on a closed single-lane circuit. By calculating a power spectral density of temporal density fluctuations at a local section, we find a power-law behavior, \\sim 1/f^{1.8}, on the frequency f, in non-congested flow phase. The distribution of the headway distance h also shows the power law like \\sim 1/h^{3.0} at the same time. The power law fluctuations are destroyed by the occurence of the traffic jam.
Renormalization group theory for temperature-driven first-order phase transitions in scalar models
Liang, Ning; Zhong, Fan
2017-12-01
We study the scaling and universal behavior of temperature-driven first-order phase transitions in scalar models. These transitions are found to exhibit rich phenomena, though they are controlled by a single complex-conjugate pair of imaginary fixed points of ϕ 3 theory. Scaling theories and renormalization group theories are developed to account for the phenomena, and three universality classes with their own hysteresis exponents are found: a field-like thermal class, a partly thermal class, and a purely thermal class, designated, respectively, as Thermal Classes I, II, and III. The first two classes arise from the opposite limits of the scaling forms proposed and may cross over to each other depending on the temperature sweep rate. They are both described by a massless model and a purely massive model, both of which are equivalent and are derived from ϕ 3 theory via symmetry. Thermal Class III characterizes the cooling transitions in the absence of applied external fields and is described by purely thermal models, which include cases in which the order parameters possess different symmetries and thus exhibit different universality classes. For the purely thermal models whose free energies contain odd-symmetry terms, Thermal Class III emerges only at the mean-field level and is identical to Thermal Class II. Fluctuations change the model into the other two models. Using the extant three- and two-loop results for the static and dynamic exponents for the Yang-Lee edge singularity, respectively, which falls into the same universality class as ϕ 3 theory, we estimate the thermal hysteresis exponents of the various classes to the same precision. Comparisons with numerical results and experiments are briefly discussed.
Fluctuation and dissipation at a quantum critical point.
Tong, David; Wong, Kenny
2013-02-08
In nonrelativistic field theories, quantum fluctuations give rise to dissipative behavior even at zero temperature. Here we use holographic methods to explore the dissipative dynamics of massive particles coupled to quantum critical theories. We present analytic expressions for correlation functions and response functions. The behavior changes qualitatively as the dynamical exponent passes through z=2. In particular, for z>2, the long-time dynamics of the particle is independent of its inertial mass.
Vara, Madeline; Roling, Luke T; Wang, Xue; Elnabawy, Ahmed O; Hood, Zachary D; Chi, Miaofang; Mavrikakis, Manos; Xia, Younan
2017-05-23
Core-shell nanocrystals offer many advantages for heterogeneous catalysis, including precise control over both the surface structure and composition, as well as reduction in loading for rare and costly metals. Although many catalytic processes are operated at elevated temperatures, the adverse impacts of heating on the shape and structure of core-shell nanocrystals are yet to be understood. In this work, we used ex situ heating experiments to demonstrate that Pd@Pt4L core-shell nanoscale cubes and octahedra are promising for catalytic applications at temperatures up to 400 °C. We also used in situ transmission electron microscopy to monitor the thermal stability of the core-shell nanocrystals in real time. Our results demonstrate a facet dependence for the thermal stability in terms of shape and composition. Specifically, the cubes enclosed by {100} facets readily deform shape at a temperature 300 °C lower than that of the octahedral counterparts enclosed by {111} facets. A reversed trend is observed for composition, as alloying between the Pd core and the Pt shell of an octahedron occurs at a temperature 200 °C lower than that for the cubic counterpart. Density functional theory calculations provide atomic-level explanations for the experimentally observed behaviors, demonstrating that the barriers for edge reconstruction determine the relative ease of shape deformation for cubes compared to octahedra. The opposite trend for alloying of the core-shell structure can be attributed to a higher propensity for subsurface Pt vacancy formation in octahedra than in cubes.
Non-Gaussian limit fluctuations in active swimmer suspensions
Kurihara, Takashi; Aridome, Msato; Ayade, Heev; Zaid, Irwin; Mizuno, Daisuke
2017-03-01
We investigate the hydrodynamic fluctuations in suspensions of swimming microorganisms (Chlamydomonas) by observing the probe particles dispersed in the media. Short-term fluctuations of probe particles were superdiffusive and displayed heavily tailed non-Gaussian distributions. The analytical theory that explains the observed distribution was derived by summing the power-law-decaying hydrodynamic interactions from spatially distributed field sources (here, swimming microorganisms). The summing procedure, which we refer to as the physical limit operation, is applicable to a variety of physical fluctuations to which the classical central limiting theory does not apply. Extending the analytical formula to compare to experiments in active swimmer suspensions, we show that the non-Gaussian shape of the observed distribution obeys the analytic theory concomitantly with independently determined parameters such as the strength of force generations and the concentration of Chlamydomonas. Time evolution of the distributions collapsed to a single master curve, except for their extreme tails, for which our theory presents a qualitative explanation. Investigations thereof and the complete agreement with theoretical predictions revealed broad applicability of the formula to dispersions of active sources of fluctuations.
Hierarchical Variational Principles of Irreversible Processes in Thermal Disturbance
Nakano, H.
1997-09-01
Quantum variational principles of irreversible processes in the linear response theory which have been developed by the present author and his coworker taking the electric conduction as an example are generalized to the transport phenomena in thermal disturbance, where the fluctuation-dissipation law is manifested. By contracting the information, the principle presented at the dynamical stage which concerns no irreversibility is converted into those at the more coarse grained stages, which concerns irreversibility. The conversion takes place from the dynamical to kinetic stage and next from the kinetic to hydrothermodynamical stage.
Effective permittivity of saline ice under thermal variation
Nghiem, S. V.; Kwok, R.; Kong, J. A.; Shin, R. T.; Gow, A. J.; Arcone, S. A.
1992-01-01
A model for calculating the effective permittivity of saline ice under thermal variation is presented. The model includes multiphase inhomogeneities with multiple species characterized by orientation, size and shape distributions. The model is used to derive the effective permittivity as a function of temperature under the strong fluctuation theory which is extended to account for the complexity. The results calculated from the model are compared with experimental data at 4.8 GHz for saline ice grown at the US Army Cold Regions Research and Engineering Laboratory (CRREL). The comparison between measured and calculated complex permittivities is good for the imaginary part, and the difference is within 10 percent for the real part.
Fluctuations and Instability in Sedimentation
Guazzelli, Élisabeth
2011-01-21
This review concentrates on the fluctuations of the velocities of sedimenting spheres, and on the structural instability of a suspension of settling fibers. For many years, theoretical estimates and numerical simulations predicted the fluctuations of the velocities of spheres to increase with the size of the container, whereas experiments found no such variation. Two ideas have increased our understanding. First, the correlation length of the velocity fluctuations was found experimentally to be 20 interparticle separations. Second, in dilute suspensions, a vertical variation in the concentration due to the spreading of the front with the clear fluid can inhibit the velocity fluctuations. In a very dilute regime, a homogeneous suspension of fibers suffers a spontaneous instability in which fast descending fiber-rich columns are separated by rising fiber-sparse columns. In a semidilute regime, the settling is hindered, more so than for spheres. © 2011 by Annual Reviews. All rights reserved.
Gaussian fluctuations in chaotic eigenstates
Srednicki, M A; Srednicki, Mark; Stiernelof, Frank
1996-01-01
We study the fluctuations that are predicted in the autocorrelation function of an energy eigenstate of a chaotic, two-dimensional billiard by the conjecture (due to Berry) that the eigenfunction is a gaussian random variable. We find an explicit formula for the root-mean-square amplitude of the expected fluctuations in the autocorrelation function. These fluctuations turn out to be O(\\hbar^{1/2}) in the small \\hbar (high energy) limit. For comparison, any corrections due to scars from isolated periodic orbits would also be O(\\hbar^{1/2}). The fluctuations take on a particularly simple form if the autocorrelation function is averaged over the direction of the separation vector. We compare our various predictions with recent numerical computations of Li and Robnik for the Robnik billiard, and find good agreement. We indicate how our results generalize to higher dimensions.
Spin-transfer torque magnetization reversal in uniaxial nanomagnets with thermal noise
Pinna, D.; Kent, A. D.; Stein, D. L.
2013-07-01
We consider the general Landau-Lifshitz-Gilbert (LLG) dynamical theory underlying the magnetization switching rates of a thin film uniaxial magnet subject to spin-torque effects and thermal fluctuations. After discussing the various dynamical regimes governing the switching phenomena, we present analytical results for the mean switching time behavior. Our approach, based on explicitly solving the first passage time problem, allows for a straightforward analysis of the thermally assisted, low spin-torque, switching asymptotics of thin film magnets. To verify our theory, we have developed an efficient Graphics Processing Unit (GPU)-based micromagnetic code to simulate the stochastic LLG dynamics out to millisecond timescales. We explore the effects of geometrical tilts between the spin-current and uniaxial anisotropy axes on the thermally assisted dynamics. We find that even in the absence of axial symmetry, the switching times can be functionally described in a form virtually identical to the collinear case.
Fluctuations and associated transport in L mode in tore supra
Energy Technology Data Exchange (ETDEWEB)
Devynck, P.; Clairet, F.; Zou, X.L.; Garbet, X.; Colas, L.; Moreau, P.; Laviron, C.; Hoang, G.T. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee]|[Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises
1997-03-01
A parametric experimental study of fluctuations has been performed in L mode plasmas during steady-state phases in Tore Supra. Simultaneous measurements of density and magnetic fluctuations in the gradient region of the discharge show that both components are strong functions of the local electron temperature decreasing lengths. The wave number spectrum of density fluctuations is obtained with the CO2 scattering diagnostic both in the bulk and at the edge of the discharge. In the bulk, in L mode compared to ohmic plasmas, the k spectrum increases below k = 7 cm{sup -1} and is globally shifted towards low k values. At the edge (r/a>0.9) an increase on all k values is observed. At r/a=0.5, the level of both types of fluctuations is found to be linearly correlated with the local heat diffusivity {chi}{sub e}. The heat flux ratio advected by electrostatic eddies in the bulk of the discharge, is estimated by using fluctuation measurements and generic predictions for the parametric dependency of the thermal flux. The calculated level of density fluctuation necessary to account for the heat transport at mid radius is found to be compatible with values measured in other tokamaks. It is also found that the heat flux ratio behaviour conducted by electrostatic fluctuations is compatible with most of the experimental heat flux ratio behaviour in the plasma core (0.4
Energy Technology Data Exchange (ETDEWEB)
Borel, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires
1970-07-01
A brief review of the basic theory of fluctuations in semiconductors is given: shot, thermal low frequency noise. A measuring set has been built to draw noise spectrums (current or voltage). Noise parameters of bipolar transistors are given, mainly noise voltage. Noise current, noise factor and correlation between noise sources are also calculated. Measurements of noise parameters fit well with theory for various devices made in different technologies: alloyed, mesa, planar. Then we give results of the calculation of noise parameters in a FET starting from a simplified model of the device. Low frequency noise is taken into account. Measurements of the parameters and of the spectrum agree fairly well with the theory. Studies of low frequency noise versus temperature give the density and energy of traps located in the space charge layers and an idea of the impurity encountered in these space charge layers. [French] On rappelle les notions de base de la theorie des fluctuations dans les semiconducteurs: bruit de grenaille, bruit thermique, bruit basse frequence. Un appareillage mis au point pour tracer un spectre de bruit est decrit. On presente ensuite le calcul des parametres de bruit d'un transistor bipolaire en insistant plus particulierement sur la tension de bruit ramenee a l'entree de l'element. Le courant de bruit, le facteur de bruit et la correlation entre les sources de bruit sont calcules. La mesure des parametres de bruit est faite sur divers elements realises dans diverses technologies: alliee, mesa et plane. Les mesures confirment tres bien la theorie. On presente ensuite le calcul des parametres de bruit d'un transistor a effet de champ en definissant un schema equivalent simple de l'element. Le calcul theorique des fluctuations basse frequence est aussi fait. La mesure du spectre de bruit confirme tres bien les calculs theoriques. L'etude du bruit basse frequence en fonction de la temperature permet de remonter a la
de Oliveira-Filho, Antonio G S; Ornellas, Fernando R; Peterson, Kirk A; Mielke, Steven L
2013-12-05
The O((3)P) + HBr → OH + Br and O((3)P) + DBr → OD + Br reactions are studied on a recent high-quality ab initio-based potential energy surface. Thermal rate constants over the 200-1000 K temperature range, calculated using variational transition-state theory (VTST) with the small-curvature tunneling (SCT) correction and quantum mechanical methods with the J-shifting approximation (QM/JS) for zero total angular momentum (J = 0), are reported. These results are compared to the available experimental data, which lie in the ranges of 221-554 and 295-419 K for O + HBr and O + DBr, respectively. The rate constants, in cm(3) molecule(-1) s(-1) and at 298 K, for the O + HBr reaction are 3.66 × 10(-14) for VTST, 3.80 × 10(-14) for QM/JS, and 3.66 × 10(-14) for the average of eight experimental measurements.
From Brownian motion to power of fluctuations
Directory of Open Access Journals (Sweden)
B. Berche
2012-12-01
Full Text Available The year 2012 marks the 140th birth anniversary of Marian Smoluchowski (28.05.1872-5.09.1917, a man who "made ground-breaking contribution to the theory of Brownian motion, the theory of sedimentation, the statistical nature of the Second Law, the theory and practice of density fluctuations (critical opalescence. During his final years of scientific creativity his pioneering theory of coagulation and diffusion-limited reaction rate appeared. These outstanding achievements present true gems which dominate the description of soft matter physics and chemical physics as well as the related areas up till now!" This quotation was taken from the lecture by Peter Hanggi given at international conference Statistical Physics: Modern Trends and Applications that took place in Lviv, Ukraine on July 3-6, 2012 (see conference web-page for more details and was dedicated to the commemoration of Smoluchowski's work. This and forthcoming issues of the Condensed Matter Physics contain papers presented at this conference.
Cosmic Infrared Background Fluctuations and Zodiacal Light
Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.
2017-01-01
We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.
Fluctuations in Hertz chains at equilibrium.
Przedborski, Michelle; Sen, Surajit; Harroun, Thad A
2017-03-01
We examine the long-term behavior of nonintegrable, energy-conserved, one-dimensional systems of macroscopic grains interacting via a contact-only generalized Hertz potential and held between stationary walls. Such systems can be set up to have no phononic background excitation and represent examples of a sonic vacuum. Existing dynamical studies showed the absence of energy equipartitioning in such systems, hence their long-term dynamics was described as quasiequilibrium. Here we show that these systems do in fact reach thermal equilibrium at sufficiently long times, as indicated by the calculated heat capacity. As a by-product, we show how fluctuations of system quantities, and thus the distribution functions, are influenced by the Hertz potential. In particular, the variance of the system's kinetic energy probability density function is reduced by a factor related to the contact potential.
Quantum spectrum as a time series: fluctuation measures.
Santhanam, M S; Bandyopadhyay, Jayendra N; Angom, Dilip
2006-01-01
The fluctuations in the quantum spectrum could be treated like a time series. In this framework, we explore the statistical self-similarity in the quantum spectrum using the detrended fluctuation analysis (DFA) and random matrix theory (RMT). We calculate the Hausdorff measure for the spectra of atoms and Gaussian ensembles and study their self-affine properties. We show that DFA is equivalent to the Delta3 statistics of RMT, unifying two different approaches. We exploit this connection to obtain theoretical estimates for the Hausdorff measure.
Suzuoka, Daiki; Takahashi, Hideaki; Morita, Akihiro
2014-04-07
We developed a perturbation approach to compute solvation free energy Δμ within the framework of QM (quantum mechanical)/MM (molecular mechanical) method combined with a theory of energy representation (QM/MM-ER). The energy shift η of the whole system due to the electronic polarization of the solute is evaluated using the second-order perturbation theory (PT2), where the electric field formed by surrounding solvent molecules is treated as the perturbation to the electronic Hamiltonian of the isolated solute. The point of our approach is that the energy shift η, thus obtained, is to be adopted for a novel energy coordinate of the distribution functions which serve as fundamental variables in the free energy functional developed in our previous work. The most time-consuming part in the QM/MM-ER simulation can be, thus, avoided without serious loss of accuracy. For our benchmark set of molecules, it is demonstrated that the PT2 approach coupled with QM/MM-ER gives hydration free energies in excellent agreements with those given by the conventional method utilizing the Kohn-Sham SCF procedure except for a few molecules in the benchmark set. A variant of the approach is also proposed to deal with such difficulties associated with the problematic systems. The present approach is also advantageous to parallel implementations. We examined the parallel efficiency of our PT2 code on multi-core processors and found that the speedup increases almost linearly with respect to the number of cores. Thus, it was demonstrated that QM/MM-ER coupled with PT2 deserves practical applications to systems of interest.
Modeling fluctuations in scattered waves
Jakeman, E
2006-01-01
Fluctuations in scattered waves limit the performance of imaging and remote sensing systems that operate on all wavelengths of the electromagnetic spectrum. To better understand these fluctuations, Modeling Fluctuations in Scattered Waves provides a practical guide to the phenomenology, mathematics, and simulation of non-Gaussian noise models and discusses how they can be used to characterize the statistics of scattered waves.Through their discussion of mathematical models, the authors demonstrate the development of new sensing techniques as well as offer intelligent choices that can be made for system analysis. Using experimental results and numerical simulation, the book illustrates the properties and applications of these models. The first two chapters introduce statistical tools and the properties of Gaussian noise, including results on phase statistics. The following chapters describe Gaussian processes and the random walk model, address multiple scattering effects and propagation through an extended med...
Nonequilibrium Fluctuational Quantum Electrodynamics: Heat Radiation, Heat Transfer, and Force
Bimonte, Giuseppe; Emig, Thorsten; Kardar, Mehran; Krüger, Matthias
2017-03-01
Quantum-thermal fluctuations of electromagnetic waves are the cornerstone of quantum statistics and inherent to phenomena such as thermal radiation and van der Waals forces. Although the principles are found in elementary texts, recent experimental and technological advances make it necessary to come to terms with counterintuitive consequences at short scales—the so-called near-field regime. We focus on three manifestations: (a) The Stefan-Boltzmann law describes radiation from macroscopic bodies but fails for small objects. (b) The heat transfer between two bodies at close proximity is dominated by evanescent waves and can be orders of magnitude larger than the classical (propagating) contribution. (c) Casimir forces, dominant at submicron separation, are not sufficiently explored for objects at different temperatures (at least experimentally). We explore these phenomena using fluctuational quantum electrodynamics (QED), introduced by Rytov in the 1950s, combined with scattering formalisms. This enables investigation of different material properties, shapes, separations, and arrangements.
Turbulent Spot Pressure Fluctuation Wave Packet Model
Energy Technology Data Exchange (ETDEWEB)
Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-05-01
Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.
Fluctuations When Driving Between Nonequilibrium Steady States
Riechers, Paul M.; Crutchfield, James P.
2017-08-01
Maintained by environmental fluxes, biological systems are thermodynamic processes that operate far from equilibrium without detailed-balanced dynamics. Yet, they often exhibit well defined nonequilibrium steady states (NESSs). More importantly, critical thermodynamic functionality arises directly from transitions among their NESSs, driven by environmental switching. Here, we identify the constraints on excess heat and dissipated work necessary to control a system that is kept far from equilibrium by background, uncontrolled "housekeeping" forces. We do this by extending the Crooks fluctuation theorem to transitions among NESSs, without invoking an unphysical dual dynamics. This and corresponding integral fluctuation theorems determine how much work must be expended when controlling systems maintained far from equilibrium. This generalizes thermodynamic feedback control theory, showing that Maxwellian Demons can leverage mesoscopic-state information to take advantage of the excess energetics in NESS transitions. We also generalize an approach recently used to determine the work dissipated when driving between functionally relevant configurations of an active energy-consuming complex system. Altogether, these results highlight universal thermodynamic laws that apply to the accessible degrees of freedom within the effective dynamic at any emergent level of hierarchical organization. By way of illustration, we analyze a voltage-gated sodium ion channel whose molecular conformational dynamics play a critical functional role in propagating action potentials in mammalian neuronal membranes.
Energy Technology Data Exchange (ETDEWEB)
Garcia B, F. B.; Arreola V, G.; Vazquez R, R.; Espinosa P, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)], e-mail: rvr@xanum.uam.mx
2009-10-15
In this work the thermal neutrons diffusion is studied with interfacial effects in a fuel-moderator arrangement that consist of an infinite series of plane fuel plates and of moderator willing so that each plate of multiplicative material has in each end a moderator plate. The developed pattern is an unidimensional model for the thermal group obtained of equation of volumetric diffusion average. One analysis of parametric sensibility was realized to find the correction constants for the diffusion coefficient, the absorption term and the new transfer or current term in the fuel-moderator interface. The obtained results are compared against the classic theory, being obtained a good agreement among both theories. (Author)
Chromodynamic Fluctuations in Quark-Gluon Plasma
Mrowczynski, Stanislaw
2008-01-01
Fluctuations of chromodynamic fields in the collisionless quark-gluon plasma are found as a solution of the initial value linearized problem. The plasma initial state is on average colorless, stationary and homogeneous. When the state is stable, the initial fluctuations decay exponentially and in the long-time limit a stationary spectrum of fluctuations is established. For the equilibrium plasma it reproduces the spectrum which is provided by the fluctuation-dissipation relation. Fluctuations...
Dynamical fluctuations in biochemical reactions and cycles
Pressé, S.; Ghosh, K.; Phillips, R.; Dill, K. A.
2010-09-01
We develop theory for the dynamics and fluctuations in some cyclic and linear biochemical reactions. We use the approach of maximum caliber, which computes the ensemble of paths taken by the system, given a few experimental observables. This approach may be useful for interpreting single-molecule or few-particle experiments on molecular motors, enzyme reactions, ion-channels, and phosphorylation-driven biological clocks. We consider cycles where all biochemical states are observable. Our method shows how: (1) the noise in cycles increases with cycle size and decreases with the driving force that spins the cycle and (2) provides a recipe for estimating small-number features, such as probability of backward spin in small cycles, from experimental data. The back-spin probability diminishes exponentially with the deviation from equilibrium. We believe this method may also be useful for other few-particle nonequilibrium biochemical reaction systems.
Gluon Green functions free of quantum fluctuations
Directory of Open Access Journals (Sweden)
A. Athenodorou
2016-09-01
Full Text Available This letter reports on how the Wilson flow technique can efficaciously kill the short-distance quantum fluctuations of 2- and 3-gluon Green functions, remove the ΛQCD scale and destroy the transition from the confining non-perturbative to the asymptotically-free perturbative sector. After the Wilson flow, the behavior of the Green functions with momenta can be described in terms of the quasi-classical instanton background. The same behavior also occurs, before the Wilson flow, at low-momenta. This last result permits applications as, for instance, the detection of instanton phenomenological properties or a determination of the lattice spacing only from the gauge sector of the theory.
Order and Symmetry Breaking in the Fluctuations of Driven Systems
Tizón-Escamilla, N.; Pérez-Espigares, C.; Garrido, P. L.; Hurtado, P. I.
2017-09-01
Dynamical phase transitions (DPTs) in the space of trajectories are one of the most intriguing phenomena of nonequilibrium physics, but their nature in realistic high-dimensional systems remains puzzling. Here we observe for the first time a DPT in the current vector statistics of an archetypal two-dimensional (2D) driven diffusive system and characterize its properties using the macroscopic fluctuation theory. The complex interplay among the external field, anisotropy, and vector currents in 2D leads to a rich phase diagram, with different symmetry-broken fluctuation phases separated by lines of first- and second-order DPTs. Remarkably, different types of 1D order in the form of jammed density waves emerge to hinder transport for low-current fluctuations, revealing a connection between rare events and self-organized structures which enhance their probability.
Energy Technology Data Exchange (ETDEWEB)
Ploetz, Elizabeth A.; Smith, Paul E. [Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan, Kansas 66506 (United States)
2015-03-07
Kirkwood-Buff or Fluctuation Solution Theory can be used to provide experimental pair fluctuations, and/or integrals over the pair distribution functions, from experimental thermodynamic data on liquid mixtures. Here, this type of approach is used to provide triplet and quadruplet fluctuations, and the corresponding integrals over the triplet and quadruplet distribution functions, in a purely thermodynamic manner that avoids the use of structure factors. The approach is then applied to binary mixtures of water + methanol and benzene + methanol over the full composition range under ambient conditions. The observed correlations between the different species vary significantly with composition. The magnitude of the fluctuations and integrals appears to increase as the number of the most polar molecule involved in the fluctuation or integral also increases. A simple physical picture of the fluctuations is provided to help rationalize some of these variations.
Non-critical Fluctuations of Liquids: Cinderella of Ultrasonic Spectroscopy?
Kaatze, U.
2014-11-01
Broadband ultrasonic spectra (100 kHz to 4.6 GHz) of aqueous solutions of organic solutes are discussed in the light of non-critical fluctuations of local concentrations. A unifying model, combining aspects of previous theories by Romanov and Solov'ev, Montrose and Litovitz, and Endo, is delineated and results from a description of spectra in terms of that model are discussed briefly. Special attention is given to aqueous solutions of some series of solutes with varying lengths and differing steric arrangements of hydrophobic groups. It is shown that, within the series of solutes with unbranched alkyl groups, the length of alkyl groups controls the correlation length of fluctuations, whereas the nature of the hydrophilic group is of minor importance in this context. Solutes with distributed hydrophobic groups reveal smaller correlation lengths. Also presented is a recent thermodynamic theory of fluctuations in surfactant solutions below the critical micelle concentration (cmc). Application of that theory shows that the predicted ultrasonic spectral function can be fitted as well to experimental spectra as that of the unifying model. Some features of the thermodynamic theory are outlined, among them the finding that the correlation length is predicted to display its maximum at a concentration below the cmc. The concentration difference, , is related to parameters of the free energy of the system.
Linear modeling of glacier fluctuations
Oerlemans, J.|info:eu-repo/dai/nl/06833656X
2012-01-01
In this contribution a linear first-order differential equation is used to model glacier length fluctuations. This equation has two parameters describing the physical characteristics of a glacier: the climate sensitivity, expressing how the equilibrium glacier length depends on the climatic state,
Reaction rates when barriers fluctuate
Reimann, Peter
1999-01-01
Reaction rates when barriers fluctuate : a path integral approach / P. Hänggi and P. Reimann. - In: International Conference on Path Integrals from peV to TeV : Proceedings of the ... / eds.: R. Casalbuoni ... - Singapore u.a. : World Scientific, 1999. - S. 407-409
Fluctuating hydrodynamics of multi-species reactive mixtures
Energy Technology Data Exchange (ETDEWEB)
Bhattacharjee, Amit Kumar; Donev, Aleksandar [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Balakrishnan, Kaushik [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192 (United States); Bell, John B. [Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)
2015-06-14
We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations.
Phase-field model of dendritic sidebranching with thermal noise
Energy Technology Data Exchange (ETDEWEB)
Karma, A. [Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115 (United States); Rappel, W. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)
1999-10-01
We investigate dendritic sidebranching during crystal growth in an undercooled melt by simulation of a phase-field model which incorporates thermal noise of microscopic origin. As a nontrivial quantitative test of this model, we first show that the simulated fluctuation spectrum of a one-dimensional interface in thermal equilibrium agrees with the exact sharp-interface spectrum up to an irrelevant short-wavelength cutoff comparable to the interface thickness. Simulations of dendritic growth are then carried out in two dimensions to compute sidebranching characteristics (root-mean-square amplitude and sidebranch spacing) as a function of distance behind the tip. These quantities are compared quantitatively to the predictions of the existing linear WKB theory of noise amplification. The extension of this study to three dimensions remains needed to determine the origin of noise in experiments. {copyright} {ital 1999} {ital The American Physical Society}
Isomorphism Between Estes’ Stimulus Fluctuation Model and a Physical- Chemical System
Directory of Open Access Journals (Sweden)
Makoto Yamaguchi
2013-10-01
Full Text Available Although Estes’ Stimulus Sampling Theory has almost completely lost its influence, its theoretical framework has not been disproved. Particularly, one theory in that framework, Stimulus Fluctuation Model, is still important because it explains spontaneous recovery. In this short note, the process of the theory is shown to be isomorphic to the diffusion of solution between compartments. Envisioning the theory as diffusion will make it appear less artificial and suggest natural extensions.
Braun-Munzinger, Peter; Redlich, Krzysztof; Stachel, Johanna
2015-01-01
We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge and strangeness from experimental data of the ALICE Collaboration at the CERN LHC. The data were taken in Pb-Pb collisions at $\\sqrt{s_{NN}}$=2.76 TeV. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature $T_c\\simeq 155$ MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at $T_c$ is found to exceed 4000 fm$^3$. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory.
Thermal Order-by-Disorder at Criticality in XY Pyrochlore Magnets
Gingras, Michel; Javanparast, Behnam; Day, Alexandre; Hao, Zhihao
2014-03-01
We investigate analytically and numerically the problem of long-range order selection via thermal fluctuations close to the critical region of the paramagnetic phase to long-range order transition in a system of interacting XY spins on the pyrochlore lattice and for which we consider the most general bilinear anisotropic nearest-neighbor spin Hamiltonian. At the standard mean-field theory (s-MFT) level, in a certain region of the parameter space of this Hamiltonian, the ordered state displays an accidental U(1) degeneracy. This degeneracy is lifted by fluctuations beyond s-MFT and a certain form of order-by-disorder near criticality is thus fund to be at play. We analytically explore this selection at the microscopic level by using an extension of the method originally developed by Thouless, Anderson and Palmer (TAP) to study the effect of fluctuations in spin glasses. These TAP calculations provide an insight into the long-range order fluctuation-induced selection mechanism in terms of the spin-spin coupling constants of the microscopic Hamiltonian. We also employ a cluster mean field theory (c-MFT) to further explore numerically this problem.
Multiscale Investigation of Thermal Fluctuations on Solar-Energy Conversion
Energy Technology Data Exchange (ETDEWEB)
Cheung, Margaret Shun [Univ. of Houston, TX (United States)
2014-09-01
Photoinduced charge transfer (CT) plays a central role in biologically significant systems and in applications that harvest solar energy. We investigate the relationship of CT kinetics and conformation in a molecular triad. The triad, consisting of carotenoid, porphyrin, and fullerene is structurally flexible and able to acquire significantly varied conformations under ambient conditions. With an integrated approach of quantum calculations and molecular dynamics simulations, we compute the rate of CT at two distinctive conformations. The linearly extended conformation, in which the donor (carotenoid) and the acceptor (fullerene) are separated by nearly 50 Å, enables charge separation through a sequential CT process. A representative bent conformation that is entropically dominant, however, attenuates the CT, although the donor and the acceptor are spatially closer. Our computed rate of CT at the linear conformation is in good agreement with measured values. Our work provides unique fundamental understanding of the photoinduced CT process in the molecular triad.
Output-input coupling in thermally fluctuating biomolecular machines
Kurzynski, Michal; Chelminiak, Przemyslaw
2011-01-01
Biological molecular machines are proteins that operate under isothermal conditions hence are referred to as free energy transducers. They can be formally considered as enzymes that simultaneously catalyze two chemical reactions: the free energy-donating reaction and the free energy-accepting one. Most if not all biologically active proteins display a slow stochastic dynamics of transitions between a variety of conformational substates composing their native state. In the steady state, this dynamics is characterized by mean first-passage times between transition substates of the catalyzed reactions. On taking advantage of the assumption that each reaction proceeds through a single pair (the gate) of conformational transition substates of the enzyme-substrates complex, analytical formulas were derived for the flux-force dependence of the both reactions, the respective stalling forces and the degree of coupling between the free energy-accepting (output) reaction flux and the free energy-donating (input) one. Th...
Bud dormancy in apple trees after thermal fluctuations
Directory of Open Access Journals (Sweden)
Rafael Anzanello
2014-06-01
Full Text Available The objective of this work was to evaluate the effect of heat waves on the evolution of bud dormancy, in apple trees with contrasting chilling requirements. Twigs of 'Castel Gala' and 'Royal Gala' were collected in orchards in Papanduva, state of Santa Catarina, Brazil, and were exposed to constant (3°C or alternating (3 and 15°C for 12/12 hours temperature, combined with zero, one or two days a week at 25°C. Two additional treatments were evaluated: constant temperature (3°C, with a heat wave of seven days at 25°C, in the beginning or in the middle of the experimental period. Periodically, part of the twigs was transferred to 25°C for daily budburst evaluation of apical and lateral buds. Endodormancy (dormancy induced by cold was overcome with less than 330 chilling hours (CH of constant cold in 'Castel Gala' and less than 618 CH in 'Royal Gala'. A daily 15°C-temperature cycle did not affect the endodormancy process. Heat waves during endodormancy resulted in an increased CH to achieve bud requirements. The negative effect of high temperature depended on the lasting of this condition. Chilling was partly cancelled during dormancy when the heat wave lasted 36 continuous hours or more. Therefore, budburst prediction models need adjustments, mainly for regions with mild and irregular winters, such as those of Southern Brazil.
Paradoxes of Thermal Radiation
Besson, U.
2009-01-01
This paper presents an analysis of the thermal behaviour of objects exposed to a solar-type flux of thermal radiation. It aims to clarify certain apparent inconsistencies between theory and observation, and to give a detailed exposition of some critical points that physics textbooks usually treat in an insufficient or incorrect way. In particular,…
Directory of Open Access Journals (Sweden)
Robitaille P.-M.
2015-04-01
Full Text Available Affirming Kirchhoff’s Law of thermal emission, Max Planck conferred upon his own equation and its constants, h and k , universal significance. All arbitrary cavities were said to behave as blackbodies. They were thought to contain b lack, or normal radiation, which depended only upon temperature and frequency of observation, irrespective of the nature of the cavity walls. Today, laboratory blackbodies a re specialized, heated devices whose interior walls are lined with highly absorptive surfaces, such as graphite, soot, or other sophisticated materials. Such evidence repeatedly calls into question Kirchhoff’s Law, as nothing in the laboratory is independent of the nature of the walls. By focusing on Max Planck’s classic text, “ The Theory of Heat Radiation ’, it can be demonstrated that the German physicist was unable to properly justify Kirchhoff’s Law. At every turn, he was confronted with the fact that materials possess frequency dependent reflectivity and absorptivity, but he often chose to sidestep these realities. He used polarized light to derive Kirchhoff’s Law, when it is well known that blackbody radiation is never polar- ized. Through the use of an element, d σ , at the bounding surface between two media, he reached the untenable position that arbitrary materials have the same reflective prop- erties. His Eq.40 ( ρ = ρ ′ , constituted a dismissal of experimental reality. It is evident that if one neglects reflection, then all cavities must be black. Unable to ensure that perfectly reflecting cavities can be filled with black radiation, Planck inserted a minute carbon particle, which he qualified as a “catalyst”. In fact, it was acting as a perfect absorber, fully able to provide, on its own, the radiation sought. In 1858, Balfour Stew- art had outlined that the proper treatment of cavity radiation must include reflection. Yet, Max Planck did not cite the Scottish scientist. He also d id not correctly address
Parity fluctuations in stellar dynamos
Moss, D. L.; Sokoloff, D. D.
2017-10-01
Observations of the solar butterfly diagram from sunspot records suggest persistent fluctuations in parity, away from the overall, approximately dipolar pattern. A simple mean-field dynamo model is used with a solar-like rotation law and perturbed α effect. The parity of the magnetic field relative to the rotational equator can demonstrate can be described as resonance behavior, while the magnetic energy behaves in a more or less expected way. Possible applications of this effect are discussed in the context of various deviations of the solar magnetic field from dipolar symmetry, as reported from analyses of archival sunspot data. The model produces fluctuations in field parity, and hence in the butterfly diagram, that are consistent with observed fluctuaions in solar behavior.
Critical Casimir force in the superfluid phase: effect of fluctuations
Biswas, Shyamal; Bhattacharjee, J K; Samanta, Himadri S.; Bhattacharyya, Saugata; Hu, Bambi
2008-01-01
We have considered the critical Casimir force on a $^4$He film below and above the bulk $\\lambda$ point. We have explored the role of fluctuations around the mean field theory in a perturbative manner, and have substantially improved the mean field result of Zandi et al [Phys. Rev. E {\\bf 76}, 030601(R) (2007)]. The Casimir scaling function obtained by us approaches a universal constant ($-\\frac{\\zeta(3)}{8\\pi}$) for $T\\lesssim 2.13~\\text{K}$.
Observational limitations of Bose-Einstein photon statistics and radiation noise in thermal emission
Lee, Y.-J.; Talghader, J. J.
2018-01-01
For many decades, theory has predicted that Bose-Einstein statistics are a fundamental feature of thermal emission into one or a few optical modes; however, the resulting Bose-Einstein-like photon noise has never been experimentally observed. There are at least two reasons for this: (1) Relationships to describe the thermal radiation noise for an arbitrary mode structure have yet to be set forth, and (2) the mode and detector constraints necessary for the detection of such light is extremely hard to fulfill. Herein, photon statistics and radiation noise relationships are developed for systems with any number of modes and couplings to an observing space. The results are shown to reproduce existing special cases of thermal emission and are then applied to resonator systems to discuss physically realizable conditions under which Bose-Einstein-like thermal statistics might be observed. Examples include a single isolated cavity and an emitter cavity coupled to a small detector space. Low-mode-number noise theory shows major deviations from solely Bose-Einstein or Poisson treatments and has particular significance because of recent advances in perfect absorption and subwavelength structures both in the long-wave infrared and terahertz regimes. These microresonator devices tend to utilize a small volume with few modes, a regime where the current theory of thermal emission fluctuations and background noise, which was developed decades ago for free-space or single-mode cavities, has no derived solutions.
Pulsed Neutron Scattering Studies of Strongly Fluctuating solids, Final Report
Energy Technology Data Exchange (ETDEWEB)
Collin Broholm
2006-06-22
The conventional description of a solid is based on a static atomic structure with small amplitude so-called harmonic fluctuations about it. This is a final technical report for a project that has explored materials where fluctuations are sufficiently strong to severely challenge this approach and lead to unexpected and potentially useful materials properties. Fluctuations are enhanced when a large number of configurations share the same energy. We used pulsed spallation source neutron scattering to obtain detailed microscopic information about structure and fluctuations in such materials. The results enhance our understanding of strongly fluctuating solids and their potential for technical applications. Because new materials require new experimental techniques, the project has also developed new techniques for probing strongly fluctuating solids. Examples of material that were studied are ZrW2O8 with large amplitude molecular motion that leads to negative thermal expansion, NiGa2S4 where competing interactions lead to an anomalous short range ordered magnet, Pr1- xBixRu2O7 where a partially filled electron shell (Pr) in a weakly disordered environment produces anomalous metallic properties, and TbMnO3 where competing interactions lead to a magneto-electric phase. The experiments on TbMnO3 exemplify the relationship between research funded by this project and future applications. Magneto-electric materials may produce a magnetic field when an electric field is applied or vise versa. Our experiments have clarified the reason why electric and magnetic polarization is coupled in TbMnO3. While this knowledge does not render TbMnO3 useful for applications it will focus the search for a practical room temperature magneto-electric for applications.
Stochastic modeling of thermal fatigue crack growth
Radu, Vasile
2015-01-01
The book describes a systematic stochastic modeling approach for assessing thermal-fatigue crack-growth in mixing tees, based on the power spectral density of temperature fluctuation at the inner pipe surface. It shows the development of a frequency-temperature response function in the framework of single-input, single-output (SISO) methodology from random noise/signal theory under sinusoidal input. The frequency response of stress intensity factor (SIF) is obtained by a polynomial fitting procedure of thermal stress profiles at various instants of time. The method, which takes into account the variability of material properties, and has been implemented in a real-world application, estimates the probabilities of failure by considering a limit state function and Monte Carlo analysis, which are based on the proposed stochastic model. Written in a comprehensive and accessible style, this book presents a new and effective method for assessing thermal fatigue crack, and it is intended as a concise and practice-or...
Fuel Temperature Fluctuations During Storage
Levitin, R. E.; Zemenkov, Yu D.
2016-10-01
When oil and petroleum products are stored, their temperature significantly impacts how their properties change. The paper covers the problem of determining temperature fluctuations of hydrocarbons during storage. It provides results of the authors’ investigations of the stored product temperature variations relative to the ambient temperature. Closeness and correlation coefficients between these values are given. Temperature variations equations for oil and petroleum products stored in tanks are deduced.
The Importance of Boundary Conditions for Fluctuation Induced Forces between Colloids at Interfaces
Lehle, H.; Oettel, M.
2006-01-01
We calculate the effective fluctuation induced force between spherical or disk-like colloids trapped at a flat, fluid interface mediated by thermally excited capillary waves. This Casimir type force is determined by the partition function of the system which in turn is calculated in a functional integral approach, where the restrictions on the capillary waves imposed by the colloids are incorporated by auxiliary fields. In the long-range regime the fluctuation induced force is shown to depend...
Energy Technology Data Exchange (ETDEWEB)
Mueller, Clemens [ARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, Brisbane (Australia); Lisenfeld, Juergen [Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe (Germany); Shnirman, Alexander [Institut fuer Theory der Kondensierten Materie, Karlsruhe Institute of Technology, Karlsruhe (Germany); LD Landau Institute for Theoretical Physics, Moscow (Russian Federation); Poletto, Stefano [IBM TJ Watson Research Centre, Yorktown Heights (United States)
2016-07-01
Since the very first experiments, superconducting circuits have suffered from strong coupling to environmental noise, destroying quantum coherence and degrading performance. In state-of-the-art experiments, it is found that the relaxation time of superconducting qubits fluctuates as a function of time. We present measurements of such fluctuations in a 3D-transmon circuit and develop a qualitative model based on interactions within a bath of background two-level systems (TLS) which emerge from defects in the device material. In our model, the time-dependent noise density acting on the qubit emerges from its near-resonant coupling to high-frequency TLS which experience energy fluctuations due to their interaction with thermally fluctuating TLS at low frequencies. We support the model by providing experimental evidence of such energy fluctuations observed in a single TLS in a phase qubit circuit.
Relationship among phenotypic plasticity, phenotypic fluctuations ...
Indian Academy of Sciences (India)
Prakash
These results provide quantitative formulation on canalization and genetic assimilation, in terms of fluctuations of gene expression levels. [Kaneko K 2009 Relationship among phenotypic plasticity, phenotypic fluctuations, robustness, and evolvability; Waddington's legacy revisited under the spirit of Einstein; J. Biosci.
Some comments to the quantum fluctuation theorems
Kuzovlev, Yu. E.
2011-01-01
It is demonstrated that today's quantum fluctuation theorems are component part of old quantum fluctuation-dissipation relations [Sov.Phys.-JETP 45, 125 (1977)], and typical misunderstandings in this area are pointed out.
Correlated interaction fluctuations in photosynthetic complexes
Vlaming, Sebastiaan M
2011-01-01
The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies of and interactions between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the interactions should in general not be neglected, as these have a considerable impact on population transfer rates, decoherence rates and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between interaction fluctuations and transition energy fluctuations, and of correlations between the various interaction fluctuations. It is shown t...
Hill, R. J.; Clifford, S. F.; Lawrence, R. S.
1980-10-01
The dependence of fluctuations in atmospheric absorption and refraction upon fluctuations in temperature, humidity, and pressure is found for infrared frequencies. This dependence has contributions from line and continuum absorption and from anomalous refraction by water vapor. The functions that relate these fluctuations are necessary for evaluating degradation of electromagnetic radiation by turbulence. They are computed for a given choice of mean atmospheric conditions and graphed as functions of frequency in the wavelength range 5.7 microns to radio waves. It is found that turbulent fluctuations in total pressure give a negligible contribution to absorption and refraction fluctuations. Humidity fluctuations dominate absorption fluctuations, but contributions by temperature and humidity affect refraction fluctuations. Sufficiently strong humidity fluctuations can dominate the refraction fluctuations for some infrared frequencies but not for visible frequencies. The variance of log amplitude is examined for scintillation of infrared light to determine whether absorption or refraction fluctuations dominate under several conditions.
Theory of heterogeneous viscoelasticity
Schirmacher, Walter; Ruocco, Giancarlo; Mazzone, Valerio
2016-03-01
We review a new theory of viscoelasticity of a glass-forming viscous liquid near and below the glass transition. In our model, we assume that each point in the material has a specific viscosity, which varies randomly in space according to a fluctuating activation free energy. We include a Maxwellian elastic term, and assume that the corresponding shear modulus fluctuates as well with the same distribution as that of the activation barriers. The model is solved in coherent potential approximation, for which a derivation is given. The theory predicts an Arrhenius-type temperature dependence of the viscosity in the vanishing frequency limit, independent of the distribution of the activation barriers. The theory implies that this activation energy is generally different from that of a diffusing particle with the same barrier height distribution. If the distribution of activation barriers is assumed to have the Gaussian form, the finite-frequency version of the theory describes well the typical low-temperature alpha relaxation peak of glasses. Beta relaxation can be included by adding another Gaussian with centre at much lower energies than that is responsible for the alpha relaxation. At high frequencies, our theory reduces to the description of an elastic medium with spatially fluctuating elastic moduli (heterogeneous elasticity theory), which explains the occurrence of the boson peak-related vibrational anomalies of glasses.
No Thermalization without Correlations
Zhdanov, Dmitry V.; Bondar, Denys I.; Seideman, Tamar
2017-10-01
The proof of the long-standing conjecture is presented that Markovian quantum master equations are at odds with quantum thermodynamics under conventional assumptions of fluctuation-dissipation theorems (implying a translation invariant dissipation). Specifically, except for identified systems, persistent system-bath correlations of at least one kind, spatial or temporal, are obligatory for thermalization. A systematic procedure is proposed to construct translation invariant bath models producing steady states that well approximate thermal states. A quantum optical scheme for the laboratory assessment of the developed procedure is outlined.
Improved thermoelectric properties of TiNiSn through enhancing strain field fluctuation
Lkhagvasuren, Enkhtaivan; Fu, Chenguang; Fecher, Gerhard H.; Auffermann, Gudrun; Kreiner, Guido; Schnelle, Walter; Felser, Claudia
2017-10-01
MNiSn (M = Hf, Zr, Ti) -based half Heusler compounds have attracted extensive attention as promising materials in thermoelectric power generation. In this work, the thermoelectric properties of the cheapest composition TiNiSn from this system are investigated. Isoelectronic substitutions of Si and Ge on Sn site are employed to reduce the lattice thermal conductivity. It is found that Si substitution leads to simultaneously enhanced mass and strain field fluctuations in TiNiSn, while the strain field fluctuation dominates the decrease of thermal conductivity in Ge substituted TiNiSn. A maximum ZT of 0.48 at 740 K is obtained in TiNiSn0.975 Ge0.025 , which is a 23% increase compared to TiNiSn. This result highlights the role of strain field fluctuation in suppressing lattice thermal conductivity and improving the thermoelectric performance of half-Heusler compounds.
Superconducting fluctuations and pseudogap in high-Tc cuprates
Directory of Open Access Journals (Sweden)
Alloul H.
2012-03-01
Full Text Available Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF to the ab-plane conductivity above Tc in a series of YBa2Cu3O6+x. These experiments allow us to determine the field Hc’(T and the temperature Tc’ above which the SCFs are fully suppressed. A careful investigation near optimal doping shows that Tc’ is higher than the pseudogap temperature T*, which is an unambiguous evidence that the pseudogap cannot be assigned to preformed pairs. Accurate determinations of the SCF contribution to the conductivity versus temperature and magnetic field have been achieved. They can be accounted for by thermal fluctuations following the Ginzburg-Landau scheme for nearly optimally doped samples. A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation. Quantitative analysis of the fluctuating magnetoconductance allows us to determine the critical field Hc2(0 which is found to be be quite similar to Hc’ (0 and to increase with hole doping. Studies of the incidence of disorder on both Tc’ and T* allow us to to propose a three dimensional phase diagram including a disorder axis, which allows to explain most observations done in other cuprate families.
Real gas effects on receptivity to kinetic fluctuations
Tumin, Anatoli; Edwards, Luke
2016-11-01
Receptivity of high-speed boundary layers is considered within the framework of fluctuating hydrodynamics where stochastic forcing is introduced through fluctuating shear stress and heat flux stemming from kinetic fluctuations (thermal noise). The forcing generates unstable modes whose amplification downstream and may lead to transition. An example of high-enthalpy (16 . 53 MJ / kg) boundary layer at relatively low wall temperatures (Tw = 1000 K - 3000 K), free stream temperature (Te = 834 K), and low pressure (0 . 0433 atm) is considered. Dissociation at the chosen flow parameters is still insignificant. The stability and receptivity analyses are carried out using a solver for calorically perfect gas with effective Prandtl number and specific heats ratio. The receptivity phenomenon is unchanged by the inclusion of real gas effects in the mean flow profiles. This is attributed to the fact that the mechanism for receptivity to kinetic fluctuations is localized near the upper edge of the boundary layer. Amplitudes of the generated wave packets are larger downstream in the case including real gas effects. It was found that spectra in both cases include supersonic second Mack unstable modes despite the temperature ratio Tw /Te > 1 . Supported by AFOSR.
Nonequilibrium fermion production in quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Pruschke, Jens
2010-06-16
The creation of matter in the early universe or in relativistic heavy-ion collisions is inevitable connected to nonequilibrium physics. One of the key challenges is the explanation of the corresponding thermalization process following nonequilibrium instabilities. The role of fermionic quantum fields in such scenarios is discussed in the literature by using approximations of field theories which neglect important quantum corrections. This thesis goes beyond such approximations. A quantum field theory where scalar bosons interact with Dirac fermions via a Yukawa coupling is analyzed in the 2PI effective action formalism. The chosen approximation allows for a correct description of the dynamics including nonequilibrium instabilities. In particular, fermion-boson loop corrections allow to study the interaction of fermions with large boson fluctuations. The applied initial conditions generate nonequilibrium instabilities like parametric resonance or spinodal instabilities. The equations of motion for correlation functions are solved numerically and major characteristics of the fermion dynamics are described by analytical solutions. New mechanisms for the production of fermions are found. Simulations in the case of spinodal instability show that unstable boson fluctuations induce exponentially growing fermion modes with approximately the same growth rate. If the unstable regime lasts long enough a thermalization of the infrared part of the fermion occupation number occurs on time scales much shorter than the time scale on which bosonic quantum fields thermalize. Fermions acquire an excess of occupation in the ultraviolet regime compared to a Fermi-Dirac statistic characterized by a power-law with exponent two. The fermion production mechanism via parametric resonance is found to be most efficient after the instability ends. Quantum corrections then provide a very efficient particle creation mechanism which is interpreted as an amplification of decay processes. The ratio
Low Mach number fluctuating hydrodynamics of multispecies liquid mixtures
Energy Technology Data Exchange (ETDEWEB)
Donev, Aleksandar, E-mail: donev@courant.nyu.edu; Bhattacharjee, Amit Kumar [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States); Nonaka, Andy; Bell, John B. [Center for Computational Science and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, San Jose, California 95192 (United States)
2015-03-15
We develop a low Mach number formulation of the hydrodynamic equations describing transport of mass and momentum in a multispecies mixture of incompressible miscible liquids at specified temperature and pressure, which generalizes our prior work on ideal mixtures of ideal gases [Balakrishnan et al., “Fluctuating hydrodynamics of multispecies nonreactive mixtures,” Phys. Rev. E 89 013017 (2014)] and binary liquid mixtures [Donev et al., “Low mach number fluctuating hydrodynamics of diffusively mixing fluids,” Commun. Appl. Math. Comput. Sci. 9(1), 47-105 (2014)]. In this formulation, we combine and extend a number of existing descriptions of multispecies transport available in the literature. The formulation applies to non-ideal mixtures of arbitrary number of species, without the need to single out a “solvent” species, and includes contributions to the diffusive mass flux due to gradients of composition, temperature, and pressure. Momentum transport and advective mass transport are handled using a low Mach number approach that eliminates fast sound waves (pressure fluctuations) from the full compressible system of equations and leads to a quasi-incompressible formulation. Thermal fluctuations are included in our fluctuating hydrodynamics description following the principles of nonequilibrium thermodynamics. We extend the semi-implicit staggered-grid finite-volume numerical method developed in our prior work on binary liquid mixtures [Nonaka et al., “Low mach number fluctuating hydrodynamics of binary liquid mixtures,” http://arxiv.org/abs/1410.2300 (2015)] and use it to study the development of giant nonequilibrium concentration fluctuations in a ternary mixture subjected to a steady concentration gradient. We also numerically study the development of diffusion-driven gravitational instabilities in a ternary mixture and compare our numerical results to recent experimental measurements [Carballido-Landeira et al., “Mixed-mode instability of a
Thermal Response Of Composite Insulation
Stewart, David A.; Leiser, Daniel B.; Smith, Marnell; Kolodziej, Paul
1988-01-01
Engineering model gives useful predictions. Pair of reports presents theoretical and experimental analyses of thermal responses of multiple-component, lightweight, porous, ceramic insulators. Particular materials examined destined for use in Space Shuttle thermal protection system, test methods and heat-transfer theory useful to chemical, metallurgical, and ceramic engineers needing to calculate transient thermal responses of refractory composites.
Khandy, Shakeel Ahmad; Islam, Ishtihadah; Ganai, Zahid Saleem; Gupta, Dinesh C.; Parrey, Khursheed Ahmad
2018-01-01
First principles calculations on the thermodynamic properties of PbTaO3 and SnAlO3 in a temperature range from 0 K to 800 K and pressure range from 0 GPa to 30 GPa have been carried out within the framework of density functional theory (DFT). The band structures of these oxides at different pressures display an increase in metallic character with a concomitant decrease in lattice constants, while the bulk modulus increases with increasing pressure. The thermal concert of these materials has been analyzed in terms of the temperature and pressure variation in Debye temperature, thermal expansion, entropy, and the Grüneisen parameter. Debye temperatures have been calculated from the elastic parameters as well as the quasi-harmonic Debye model, which are 339.07 GPa for PbTaO3 and 714.36 GPa for SnAlO3.
Landau, Lev Davidovich; Kosevich, A M; Pitaevskii, Lev Petrovich
1986-01-01
A comprehensive textbook covering not only the ordinary theory of the deformation of solids, but also some topics not usually found in textbooks on the subject, such as thermal conduction and viscosity in solids.
Chaotic fluctuations in mathematical economics
Energy Technology Data Exchange (ETDEWEB)
Yoshida, Hiroyuki, E-mail: yoshida.hiroyuki@nihon-u.ac.jp [College of Economics, Nihon University, Chiyoda-ku, Tokyo 101-8360 (Japan)
2011-03-01
In this paper we examine a Cournot duopoly model, which expresses the strategic interaction between two firms. We formulate the dynamic adjustment process and investigate the dynamic properties of the stationary point. By introducing a memory mechanism characterized by distributed lag functions, we presuppose that each firm makes production decisions in a cautious manner. This implies that we have to deal with the system of integro-differential equations. By means of numerical simulations we show the occurrence of chaotic fluctuations in the case of fixed delays.
Noise and fluctuations an introduction
MacDonald, D K C
2006-01-01
An understanding of fluctuations and their role is both useful and fundamental to the study of physics. This concise study of random processes offers graduate students and research physicists a survey that encompasses both the relationship of Brownian Movement with statistical mechanics and the problem of irreversible processes. It outlines the basics of the physics involved, without the strictures of mathematical rigor.The three-part treatment starts with a general survey of Brownian Movement, including electrical Brownian Movement and ""shot-noise,"" Part two explores correlation, frequency
All Shook Up: Fluctuations, Maxwell’s Demon and the Thermodynamics of Computation
Directory of Open Access Journals (Sweden)
John D. Norton
2013-10-01
Full Text Available The most successful exorcism of Maxwell’s demon is Smoluchowski’s 1912 observation that thermal fluctuations would likely disrupt the operation of any molecular-scale demonic machine. A later tradition sought to exorcise Maxwell’s demon by assessing the entropic cost of the demon’s processing of information. This later tradition fails since these same thermal fluctuations invalidate the molecular-scale manipulations upon which the thermodynamics of computation is based. A new argument concerning conservation of phase space volume shows that all Maxwell’s demons must fail.
Work Fluctuation-Dissipation Trade-Off in Heat Engines.
Funo, Ken; Ueda, Masahito
2015-12-31
Reducing work fluctuation and dissipation in heat engines or, more generally, information heat engines that perform feedback control, is vital to maximize their efficiency. The same problem arises when we attempt to maximize the efficiency of a given thermodynamic task that undergoes nonequilibrium processes for arbitrary initial and final states. We find that the most general trade-off relation between work fluctuation and dissipation applicable to arbitrary nonequilibrium processes is bounded from below by the information distance characterizing how far the system is from thermal equilibrium. The minimum amount of dissipation is found to be given in terms of the relative entropy and the Renyi divergence, both of which quantify the information distance between the state of the system and the canonical distribution. We give an explicit protocol that achieves the fundamental lower bound of the trade-off relation.
An objective fluctuation score for Parkinson's disease.
Directory of Open Access Journals (Sweden)
Malcolm K Horne
Full Text Available Establishing the presence and severity of fluctuations is important in managing Parkinson's Disease yet there is no reliable, objective means of doing this. In this study we have evaluated a Fluctuation Score derived from variations in dyskinesia and bradykinesia scores produced by an accelerometry based system.The Fluctuation Score was produced by summing the interquartile range of bradykinesia scores and dyskinesia scores produced every 2 minutes between 0900-1800 for at least 6 days by the accelerometry based system and expressing it as an algorithm.This Score could distinguish between fluctuating and non-fluctuating patients with high sensitivity and selectivity and was significant lower following activation of deep brain stimulators. The scores following deep brain stimulation lay in a band just above the score separating fluctuators from non-fluctuators, suggesting a range representing adequate motor control. When compared with control subjects the score of newly diagnosed patients show a loss of fluctuation with onset of PD. The score was calculated in subjects whose duration of disease was known and this showed that newly diagnosed patients soon develop higher scores which either fall under or within the range representing adequate motor control or instead go on to develop more severe fluctuations.The Fluctuation Score described here promises to be a useful tool for identifying patients whose fluctuations are progressing and may require therapeutic changes. It also shows promise as a useful research tool. Further studies are required to more accurately identify therapeutic targets and ranges.
Carollo, Federico; Garrahan, Juan P.; Lesanovsky, Igor; Pérez-Espigares, Carlos
2017-11-01
We consider a class of either fermionic or bosonic noninteracting open quantum chains driven by dissipative interactions at the boundaries and study the interplay of coherent transport and dissipative processes, such as bulk dephasing and diffusion. Starting from the microscopic formulation, we show that the dynamics on large scales can be described in terms of fluctuating hydrodynamics. This is an important simplification as it allows us to apply the methods of macroscopic fluctuation theory to compute the large deviation (LD) statistics of time-integrated currents. In particular, this permits us to show that fermionic open chains display a third-order dynamical phase transition in LD functions. We show that this transition is manifested in a singular change in the structure of trajectories: while typical trajectories are diffusive, rare trajectories associated with atypical currents are ballistic and hyperuniform in their spatial structure. We confirm these results by numerically simulating ensembles of rare trajectories via the cloning method, and by exact numerical diagonalization of the microscopic quantum generator.
Statistical Analysis of Thomson Scattering Measurements for High-Frequency Temperature Fluctuations
Morton, Lucas; den Hartog, Daniel; Parke, Eli; Duff, James; Lin, Liang
2014-10-01
The MST Thomson Scattering (TS) Diagnostic is used to study electron temperature (Te) fluctuations at frequencies (lasers can fire 4-5 pulses at repetition rate of 12.5 kHz. Adjusting the time delay between the lasers (as low as 1 μs) allows probing of high-frequency (up to 1 MHz) fluctuations by autocorrelating the resulting Te measurements. This technique's effectiveness is demonstrated by comparing its results to those of tearing-mode-correlation studies. In 400 kA standard MST discharges, the dominant tearing modes have associated Te fluctuations of up to 25 +/- 5eV in the core. The TS autocorrelation measures total fluctuations of 42 +/- 5eV, indicating that tearing comprises much of the core Te fluctuations. With improved laser alignment, we investigate 400 kA improved confinement (PPCD) plasmas where global tearing activity is reduced and electrostatic turbulence may dominate electron thermal transport and fluctuation power. We also find no significant Te fluctuation (<5eV) correlated with edge-localized density fluctuations seen by the FIR interferometer in 200kA PPCD plasmas. This work supported by the US DOE and NSF.
Berritta, Marco; Manrique, David Zs; Lambert, Colin J
2015-01-21
We theoretically explored the combined role of conformational fluctuations and quantum interference in determining the electrical conductance of single-molecule break junctions. In particular we computed the conductance of a family of methylsulfide-functionalized trans-α,ω-diphenyloligoene molecules, with terminal phenyl rings containing meta or para linkages, for which (at least in the absence of fluctuations) destructive interference in the former is expected to decrease their electrical conductance compared with the latter. We compared the predictions of density functional theory (DFT), in which fluctuational effects are absent, with results for the conformationally-averaged conductance obtained from an ensemble of conformations obtained from classical molecular dynamics. We found that junctions formed from these molecules exhibit distinct transport regimes during junction evolution and the signatures of quantum interference in these molecules survive the effect of conformational fluctuations. Furthermore, the agreement between theory and experiment is significantly improved by including conformational averaging.
DEFF Research Database (Denmark)
Chen, Qi; Zuo, Min; Yang, Ruiquan
2017-01-01
and the linearized Cahn–Hilliard theory could describe the amplitude evolution of concentration fluctuation at the early stage of phase separation. Hydrophilic nanosilica A200 dispersed in PVME-rich phase behaved an obvious inhibition effect on the concentration fluctuation of blend matrix, while hydrophobic...
Arrese-Igor, S.; Alegría, A.; Colmenero, J.
2014-08-01
The slowest (p=1) mode relaxation of several polyisoprenes has been experimentally isolated by thermally stimulated depolarization current techniques. Close to the glass transition the p=1 mode deviates from the exponential behavior assumed by Rouse and tube-reptation theories. This effect is found to be a consequence of the closeness of τp =1 and α-relaxation time scales. The scenario resembles that of broadened fast component dynamics in polymer blends with high dynamic asymmetry and suggests a possible general interpretation in terms of the effect of local density fluctuations (α relaxation) on chain dynamics.
Thermal sine-Gordon system in the presence of different types of dissipation
DEFF Research Database (Denmark)
Salerno, M.; Samuelsen, Mogens Rugholm; Svensmark, Henrik
1988-01-01
The effects of thermal fluctuations on solitons and phonons of the sine-Gordon system are investigated in the presence of a αφt-βφxxt dissipation. The analysis requires the assumption of a more general autocorrelation function for the noise than the one used in previous works. We verify...... that this leads to the correct results for the average kinetic energies of solitons and phonons in the system. We also evaluate the linewidth for a Josephson oscillator in the presence of both α and β dissipation, and lastly we briefly discuss the extension of the theory to more general dissipative terms....
VIEWS OF ROMANIAN ECONOMISTS ON THE CYCLICAL FLUCTUATIONS IN ECONOMY
Directory of Open Access Journals (Sweden)
Pitorac Ruxandra
2013-07-01
Full Text Available As part of a larger work, the objective of this article is to identify the Romanian economists concerned with the study of economic crisis and cyclical fluctuations and to critically and theoretically review the Romanian literature on this subject. The research is a qualitative one and it is based upon the studying of the specialized intern literature, the tools for this research were analysis and synthesis. The study of the Romanian economic thought, concerned with explaining the causes of cyclical fluctuations, has a special importance in understanding the economic system, in general, and in taking the right measures in mitigating the fluctuations and in economic recovery after a crisis period, in particular. The starting point of the theories regarding the cyclical fluctuations in Romania is 1929, when the economic crisis broke out, with serious effects on the development of Romania. An extensive literature has been written on the economic crisis of 1929-1933, in which Romanian economists exposed their views on the causes that generated it and the solutions to get out of that state. The same thing happened during the crisis in 2008-2010. When its effects were felt in Romania, the national economists tried to explain the causes of economic crisis, as well as finding ways of recovery for the Romanian economy. The research reveals the fact that all the analyzed theories, regardless of the historical period, considered the causes of cyclical fluctuation, in general, and the causes of economic crises, in particular, as being endogenous. (technical progress, investment, consumption, production variation, overcapitalization The presentation of the economists who were concerned by this research is not exhaustive but selective and the most representative were elected to the matter under discussion, based upon the impact of their research on the economic fluctuation theories. It is necessary to take into account the nature of the economic and social
Fluctuations in work motivation: tasks do not matter!
Navarro, Jose; Curioso, Fernando; Gomes, Duarte; Arrieta, Carlos; Cortes, Mauricio
2013-01-01
Previous studies have shown that work motivation fluctuates considerably and in a nonlinear way over time. In the present research, we are interested in studying if the task at hand does or does not influence the presence of these fluctuations. We gathered daily registers from 69 workers during 21 consecutive working days (7036 registers) of task developed and levels of motivation, self-efficacy beliefs and instrumentalities perception. These registers were then categorized into a list of labor activities in main tasks and subtasks by means of three judges with a high level of agreement (97.47% for tasks, and 98.64% for subtasks). Taking the MSSD statistic (mean squared successive difference) of the average of motivation, self-efficacy and instrumentality, and using hierarchical regression analysis we have found that tasks (beta = .03; p = .188) and subtasks (beta = .10; p = .268) do not affect the presence of fluctuations in motivation. These results reveal instability in work motivation independently from the tasks and subtasks that the workers do. We proceed to find that fluctuations in work motivation show a fractal structure across the different tasks we do in a working day. Implications of these results to motivational theory will be discussed as well as possible explanations (e.g. the influence of affect in work motivation) and directions for future research are provided.
On spherical dust fluctuations: the exact vs. the perturbative approach
Sussman, Roberto A; Dunsby, Peter K S; German, Gabriel
2014-01-01
We examine the relation between the dynamics of Lema\\^{\\i}tre-Tolman-Bondi (LTB) dust models (with and without $\\Lambda$) and the dynamics of dust perturbations in two of the more familiar formalisms used in cosmology: the metric based Cosmological Perturbation Theory (CPT) and the Covariant Gauge Invariant (GIC) perturbations. For this purpose we recast the evolution of LTB models in terms of a covariant and gauge invariant formalism of local and non-local "exact fluctuations " on a Friedmann-Lema\\^{\\i}tre-Robertson-Walker (FLRW) background defined by suitable averages of covariant scalars. We examine the properties of these fluctuations, which can be defined for a confined comoving domain or for an asymptotic domain extending to whole time slices. In particular, the non-local density fluctuation provides a covariant and precise definition for the notion of the "density contrast ". We show that in their linear regime these LTB exact fluctuations (local and non-local) are fully equivalent to the conventional ...
Propagation of radio frequency waves through density fluctuations
Valvis, S. I.; Papagiannis, P.; Papadopoulos, A.; Hizanidis, K.; Glytsis, E.; Bairaktaris, F.; Zisis, A.; Tigelis, I.; Ram, A. K.
2017-10-01
On their way to the core of a tokamak plasma, radio frequency (RF) waves, excited in the vacuum region, have to propagate through a variety of density fluctuations in the edge region. These fluctuations include coherent structures, like blobs that can be field aligned or not, as well as turbulent and filamentary structures. We have been studying the effect of fluctuations on RF propagation using both theoretical (analytical) and computational models. The theoretical results are being compared with those obtained by two different numerical codes ``a Finite Difference Frequency Domain code and the commercial COMSOL package. For plasmas with arbitrary distribution of coherent and turbulent fluctuations, we have formulated an effective dielectric permittivity of the edge plasma. This permittivity tensor is then used in numerical simulations to study the effect of multi-scale turbulence on RF waves. We not only consider plane waves but also Gaussian beams in the electron cyclotron and lower hybrid range of frequencies. The analytical theory and results from simulations on the propagation of RF waves will be presented. Supported in part by the Hellenic National Programme on Controlled Thermonuclear Fusion associated with the EUROfusion Consortium and by DoE Grant DE-FG02-91ER-54109.
Fluctuations of absorption of interacting diffusing particles by multiple absorbers
Agranov, Tal; Meerson, Baruch
2017-06-01
We study fluctuations of particle absorption by a three-dimensional domain with multiple absorbing patches. The domain is in contact with a gas of interacting diffusing particles. This problem is motivated by living cell sensing via multiple receptors distributed over the cell surface. Employing the macroscopic fluctuation theory, we calculate the covariance matrix of the particle absorption by different patches, extending previous works which addressed fluctuations of a single current. We find a condition when the sign of correlations between different patches is fully determined by the transport coefficients of the gas and is independent of the problem's geometry. We show that the fluctuating particle flux field typically develops vorticity. We establish a simple connection between the statistics of particle absorption by all the patches combined and the statistics of current in a nonequilibrium steady state in one dimension. We also discuss connections between the absorption statistics and (i) statistics of electric currents in multiterminal diffusive conductors and (ii) statistics of wave transmission through disordered media with multiple absorbers.
Energy Technology Data Exchange (ETDEWEB)
Calleja, Mark [Cambridge eScience Centre, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Goodwin, Andrew L; Dove, Martin T [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom)], E-mail: mtd10@cam.ac.uk
2008-06-25
DFT calculations have been used to provide insights into the origin of the colossal positive and negative thermal expansion in Ag{sub 3}[Co(CN){sub 6}]. The results confirm that the positive expansion within the trigonal basal plane and the negative expansion in the orthogonal direction are coupled due to the existence of a network defined by nearly rigid bonds within the chains of Co-C-N-Ag-N-C-Co linkages. The origin of the colossal values of the coefficients of thermal expansion arise from an extremely shallow energy surface that allows a flexing of the structure with small energy cost. The thermal expansion can be achieved with a modest value of the overall Grueneisen parameter. The energy surface is so shallow that we need to incorporate a small empirical dispersive interaction to give ground-state lattice parameters that match experimental values at low temperature. We compare the results with DFT calculations on two isostructural systems: H{sub 3}[Co(CN){sub 6}], which is known to have much smaller values of the coefficients of thermal expansion, and Au{sub 3}[Co(CN){sub 6}], which has not yet been synthesized but which is predicted by our calculations to be another candidate material for showing colossal positive and negative thermal expansion.
Multifractal conductance fluctuations in graphene
Bid, Aveek; Rafsanjani Amin, Kazi; Pal, Nairita; Sankar Ray, Samriddhi; Pandit, Rahul
A multifractal (MF) system is characterized by scaling laws involving an infinite number of exponents. In condensed-matter systems, signatures of multifractality have typically been found in the structure of the critical wave functions at localization delocalization (LD) transitions. We report here the first experimental observation of MF statistics in the transport coefficients of a quantum-condensed matter system. We unearth this through a careful investigation of the magneto-conductance fluctuations in ultra-high mobility single layer graphene at ultra-low temperatures. We obtain the MF spectra over a wide range of temperature and doping levels and show that the multifractality decreases as the temperature increases or as the doping moves the system away from the Dirac point. We show that the fractal exponents are a universal function of the phase coherence length of the carriers. We propose that a probable origin of the MF magneto-conductance fluctuations observed by us is an incipient Anderson LD transition in graphene near the charge neutrality point - a phenomenon predicted but never observed in single layer graphene. We also explore alternate possibilities of the origin of the multifractality namely relativistic quantum scars. AB acknowledges funding from Nanomission, DST, Govt. of India and SERB, DST, Govt. of India.
Protrusion Fluctuations Direct Cell Motion
Caballero, David; Voituriez, Raphaël; Riveline, Daniel
2014-01-01
Many physiological phenomena involve directional cell migration. It is usually attributed to chemical gradients in vivo. Recently, other cues have been shown to guide cells in vitro, including stiffness/adhesion gradients or micropatterned adhesive motifs. However, the cellular mechanism leading to these biased migrations remains unknown, and, often, even the direction of motion is unpredictable. In this study, we show the key role of fluctuating protrusions on ratchet-like structures in driving NIH3T3 cell migration. We identified the concept of efficient protrusion and an associated direction index. Our analysis of the protrusion statistics facilitated the quantitative prediction of cell trajectories in all investigated conditions. We varied the external cues by changing the adhesive patterns. We also modified the internal cues using drug treatments, which modified the protrusion activity. Stochasticity affects the short- and long-term steps. We developed a theoretical model showing that an asymmetry in the protrusion fluctuations is sufficient for predicting all measures associated with the long-term motion, which can be described as a biased persistent random walk. PMID:24988339
Entropic fluctuations in DNA sequences
Thanos, Dimitrios; Li, Wentian; Provata, Astero
2018-03-01
The Local Shannon Entropy (LSE) in blocks is used as a complexity measure to study the information fluctuations along DNA sequences. The LSE of a DNA block maps the local base arrangement information to a single numerical value. It is shown that despite this reduction of information, LSE allows to extract meaningful information related to the detection of repetitive sequences in whole chromosomes and is useful in finding evolutionary differences between organisms. More specifically, large regions of tandem repeats, such as centromeres, can be detected based on their low LSE fluctuations along the chromosome. Furthermore, an empirical investigation of the appropriate block sizes is provided and the relationship of LSE properties with the structure of the underlying repetitive units is revealed by using both computational and mathematical methods. Sequence similarity between the genomic DNA of closely related species also leads to similar LSE values at the orthologous regions. As an application, the LSE covariance function is used to measure the evolutionary distance between several primate genomes.
Consistency of detrended fluctuation analysis
Løvsletten, O.
2017-07-01
The scaling function F (s ) in detrended fluctuation analysis (DFA) scales as F (s ) ˜sH for stochastic processes with Hurst exponent H . This scaling law is proven for stationary stochastic processes with 0 DFA is equal in expectation to (i) a weighted sum of the ACF and (ii) a weighted sum of the second-order structure function. These results enable us to compute the exact finite-size bias for signals that are scaling and to employ DFA in a meaningful sense for signals that do not exhibit power-law statistics. The usefulness is illustrated by examples where it is demonstrated that a previous suggested modified DFA will increase the bias for signals with Hurst exponents 1 application of these developments, an estimator F ̂(s ) is proposed. This estimator can handle missing data in regularly sampled time series without the need of interpolation schemes. Under mild regularity conditions, F ̂(s ) is equal in expectation to the fluctuation function F (s ) in the gap-free case.
Determination of the Thermal Noise Limit of Graphene Biotransistors.
Crosser, Michael S; Brown, Morgan A; McEuen, Paul L; Minot, Ethan D
2015-08-12
To determine the thermal noise limit of graphene biotransistors, we have measured the complex impedance between the basal plane of single-layer graphene and an aqueous electrolyte. The impedance is dominated by an imaginary component but has a finite real component. Invoking the fluctuation-dissipation theorem, we determine the power spectral density of thermally driven voltage fluctuations at the graphene/electrolyte interface. The fluctuations have 1/f(p) dependence, with p = 0.75-0.85, and the magnitude of fluctuations scales inversely with area. Our results explain noise spectra previously measured in liquid-gated suspended graphene devices and provide realistic targets for future device performance.
Import Response to Exchange Rate Fluctuations: A Micro-level Investigation
Yao Amber Li; Jenny Xu; Carol Zhao Chen
2015-01-01
This paper presents theory and evidence on firms' import responses to exchange rate fluctuations using disaggregated Chinese imports data. The paper develops a heterogeneous-firm trade model that predicts import responses at both extensive and intensive margins as well as the more profound adjustment under ordinary trade than processing trade. Next, the paper empirically investigates import responses to exchange rate fluctuations at extensive and intensive margins in both the short run and th...
AM05-12-001 Large-scale Fluctuation of Turbulence Energy Dissipation
毛利, 英明; 高岡, 正憲; 堀, 晃浩; 川島, 儀英; H, MOURI; M., Takaoka; A., Hori; Y., Kawashima; 同志社大学工学部; 気象研究所; Doshisha University; Meteorological Research Institute
2005-01-01
Kolmogorov's theory for turbulence in 1941 is based on a hypothesis that small-scale statistics are uniquely determined by the kinematic viscosity and the mean rate of energy dissipation. Landau remarked that the local rate of energy dissipation should fluctuate in space over scales of large eddies and hence should affect small-scale statistics. Experimentally, we confirm the significance of this fluctuation, which is comparable to the mean rate of energy dissipation at the typical scale of l...
On Landau's prediction for large-scale fluctuation of turbulence energy dissipation
Mouri, H.; Takaoka, M.; Hori, A.; Kawashima, Y.
2005-01-01
Kolmogorov's theory for turbulence in 1941 is based on a hypothesis that small-scale statistics are uniquely determined by the kinematic viscosity and the mean rate of energy dissipation. Landau remarked that the local rate of energy dissipation should fluctuate in space over large scales and hence should affect small-scale statistics. Experimentally, we confirm the significance of this large-scale fluctuation, which is comparable to the mean rate of energy dissipation at the typical scale fo...
Fluctuations of local electric field and dipole moments in water between metal walls.
Takae, Kyohei; Onuki, Akira
2015-10-21
We examine the thermal fluctuations of the local electric field Ek (loc) and the dipole moment μk in liquid water at T = 298 K between metal walls in electric field applied in the perpendicular direction. We use analytic theory and molecular dynamics simulation. In this situation, there is a global electrostatic coupling between the surface charges on the walls and the polarization in the bulk. Then, the correlation function of the polarization density pz(r) along the applied field contains a homogeneous part inversely proportional to the cell volume V. Accounting for the long-range dipolar interaction, we derive the Kirkwood-Fröhlich formula for the polarization fluctuations when the specimen volume v is much smaller than V. However, for not small v/V, the homogeneous part comes into play in dielectric relations. We also calculate the distribution of Ek (loc) in applied field. As a unique feature of water, its magnitude |Ek (loc)| obeys a Gaussian distribution with a large mean value E0 ≅ 17 V/nm, which arises mainly from the surrounding hydrogen-bonded molecules. Since |μk|E0 ∼ 30kBT, μk becomes mostly parallel to Ek (loc). As a result, the orientation distributions of these two vectors nearly coincide, assuming the classical exponential form. In dynamics, the component of μk(t) parallel to Ek (loc)(t) changes on the time scale of the hydrogen bonds ∼5 ps, while its smaller perpendicular component undergoes librational motions on time scales of 0.01 ps.
Snicker, A.; Poli, E.; Maj, O.; Guidi, L.; Köhn, A.; Weber, H.; Conway, G. D.; Henderson, M.; Saibene, G.
2018-01-01
We present a numerical investigation of electron cyclotron beams interacting with electron density fluctuations in the ITER 15 MA H-mode scenario. In particular, here we study how the beam from the equatorial launcher, which shall be utilized to influence the sawtooth instability, is affected by the fluctuations. Moreover, we present the theory and first estimates of the power that is scattered from the injected O-mode to a secondary X-mode in the presence of the fluctuations. It is shown that for ITER parameters the scattered power stays within acceptable limits and broadening of the equatorial beams is less than those from the upper launcher.
National Research Council Canada - National Science Library
Hualin Xie; Bohao Wang
2017-01-01
.... Based on agricultural production data from 1970 to 2015, this paper explores the influence of agricultural product price fluctuation on grain production by using the cobweb theory and vector error correction (VEC) model...
A Facile Approach to Evaluate Thermal Insulation Performance of Paper Cups
Directory of Open Access Journals (Sweden)
Yudi Kuang
2015-01-01
Full Text Available Paper cups are ubiquitous in daily life for serving water, soup, coffee, tea, and milk due to their convenience, biodegradability, recyclability, and sustainability. The thermal insulation performance of paper cups is of significance because they are used to supply hot food or drinks. Using an effective thermal conductivity to accurately evaluate the thermal insulation performance of paper cups is complex due to the inclusion of complicated components and a multilayer structure. Moreover, an effective thermal conductivity is unsuitable for evaluating thermal insulation performance of paper cups in the case of fluctuating temperature. In this work, we propose a facile approach to precisely analyze the thermal insulation performance of paper cups in a particular range of temperature by using an evaluation model based on the MISO (Multiple-Input Single-Output technical theory, which includes a characterization parameter (temperature factor and a measurement apparatus. A series of experiments was conducted according to this evaluation model, and the results show that this evaluation model enables accurate characterization of the thermal insulation performance of paper cups and provides an efficient theoretical basis for selecting paper materials for paper cups.
Mojahedi, Mahdi; Shekoohinejad, Hamidreza
2018-02-01
In this paper, temperature distribution in the continuous and pulsed end-pumped Nd:YAG rod crystal is determined using nonclassical and classical heat conduction theories. In order to find the temperature distribution in crystal, heat transfer differential equations of crystal with consideration of boundary conditions are derived based on non-Fourier's model and temperature distribution of the crystal is achieved by an analytical method. Then, by transferring non-Fourier differential equations to matrix equations, using finite element method, temperature and stress of every point of crystal are calculated in the time domain. According to the results, a comparison between classical and nonclassical theories is represented to investigate rupture power values. In continuous end pumping with equal input powers, non-Fourier theory predicts greater temperature and stress compared to Fourier theory. It also shows that with an increase in relaxation time, crystal rupture power decreases. Despite of these results, in single rectangular pulsed end-pumping condition, with an equal input power, Fourier theory indicates higher temperature and stress rather than non-Fourier theory. It is also observed that, when the relaxation time increases, maximum amounts of temperature and stress decrease.
Mojahedi, Mahdi; Shekoohinejad, Hamidreza
2017-11-01
In this paper, temperature distribution in the continuous and pulsed end-pumped Nd:YAG rod crystal is determined using nonclassical and classical heat conduction theories. In order to find the temperature distribution in crystal, heat transfer differential equations of crystal with consideration of boundary conditions are derived based on non-Fourier's model and temperature distribution of the crystal is achieved by an analytical method. Then, by transferring non-Fourier differential equations to matrix equations, using finite element method, temperature and stress of every point of crystal are calculated in the time domain. According to the results, a comparison between classical and nonclassical theories is represented to investigate rupture power values. In continuous end pumping with equal input powers, non-Fourier theory predicts greater temperature and stress compared to Fourier theory. It also shows that with an increase in relaxation time, crystal rupture power decreases. Despite of these results, in single rectangular pulsed end-pumping condition, with an equal input power, Fourier theory indicates higher temperature and stress rather than non-Fourier theory. It is also observed that, when the relaxation time increases, maximum amounts of temperature and stress decrease.
Theory of economic cycle: analysis of аustrian school
Nesterenko, O.
2008-01-01
Essence of Austrian theory of economic cycle has been revealed. Differences of Austrian school approaches from theories of economic fluctuations in other streams of economic sciences have been analyzed
Fluctuation-dissipation theorem in isolated quantum systems out of equilibrium
Khatami, Ehsan; Pupillo, Guido; Srednicki, Mark; Rigol, Marcos
2014-05-01
We study the validity of the fluctuation-dissipation theorem for an isolated quantum system of harmonically trapped dipolar molecules taken out of equilibrium by means of a quench, a sudden change in the Hamiltonian parameters. We find that the integrability of the system plays a crucial role in the validity of the fluctuation-dissipation theorem. Namely, the system thermalizes according to the eigenstate thermalization hypothesis and the theorem holds if the system is nonintegrable after the quench. However, it fails if the system is integrable, unless the initial state is an eigenstate of a nonintegrable Hamiltonian, in which case the system still thermalizes despite the eigenstate thermalization hypothesis failing to describe it.
Hellmann, Robert; Bich, Eckard; Vesovic, Velisa
2016-04-07
The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Z(rot), for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter.
Vacuum Fluctuations, Cosmogenesis and Prime Number Gaps
Berezin, Alexander A.
2002-10-01
Starting from E.Tryon (1973), idea of cosmogenesis through quantum tunnelling "from nothing" became popular. Both complimentary streams of it, inflationary models (Guth, Linde) and quantum parallelism (Everett, Deutsch), require some starting point as, e.g., concretisation of Leibnitz Principle (Omnibus ex nihil decendis sufficit unum). This leads to propositional conjecture (axiom?) that (meta)physical "Platonic Pressure" of infinitude of numbers and Cantor "alephs" becomes an engine for self-generation of physical universe directly out of mathematics: inexhaustibility of Number Theory (NT) drives cosmogenesis. While physics in other quantum branches of inflating universe (Megaverse) can be (arbitrary) different from ours, NT is not (it is unique, absolute, immutable and infinitely resourceful). Energy-time uncertainty principle (UP) allows indefinite lifetime provided we start from total zero energy. Analogue of UP in NT is theorem by H.Maier (1981) stating the existence of arbitrary long trails of isolated primes such that each next gap is arbitrary greater than average gap (logN). On physical level these arbitrary large deviations from Prime Number Theorem translate into permissiveness of (arbitrary) large quantum fluctuations.
Spontaneous emission of electromagnetic fluctuations in Kappa magnetized plasmas
Kim, Sunjung; Schlickeiser, R.; Yoon, P. H.; López, R. A.; Lazar, M.
2017-12-01
The present paper formulates the theory of spontaneously emitted electromagnetic (EM) fluctuations in magnetized plasmas containing particles with an anisotropic suprathermal (bi-Kappa) velocity distribution function. The formalism is general applying for an arbitrary wave vector orientation and wave polarization, and for any wave-frequency range. As a specific application, the high-frequency EM fluctuations emitted in the upper-hybrid and multiple harmonic electron cyclotron frequency range are evaluated. The model predictions are confirmed by a comparison with the particle-in-cell simulations. Theoretical analysis and numerical simulations are carried out for an isotropic Kappa but the formalism can be applied for any anisotropic distributions, as well as for lower frequencies ranges which involve the ion response.
Effects of quantum fluctuations of metric on the universe
Yang, Rongjia
2016-09-01
We consider a model of modified gravity from the nonperturbative quantization of a metric. We obtain the modified gravitational field equations and the modified conservational equations. We apply it to the FLRW spacetime and find that due to the quantum fluctuations a bounce universe can be obtained and a decelerated expansion can also possibly be obtained in a dark energy dominated epoch. We also discuss the effects of quantum fluctuations on inflation parameters (such as slow-roll parameters, spectral index, and the spectrum of the primordial curvature perturbation) and find values of parameters in the comparing the predictions of inflation can also work to drive the current epoch of acceleration. We obtain the constraints on the parameter of the theory from the observation of the big bang nucleosynthesis.
Comparison of edge fluctuations in toroidal confinement devices
Energy Technology Data Exchange (ETDEWEB)
Tsui, H.Y.W.; Lin, H.; Meier, M.; Ritz, C.; Wooton, A.J. (Texas Univ., Austin, TX (United States). Fusion Research Center)
1991-01-01
Tokamak, Stellarator and RFP confinement systems have similar topology but differ markedly in their equilibrium configurations. Experiments to date show that the particles and energy losses in these systems are higher than those predicted from (neo)classical theories. The anomalously high particle and energy fluxes are often attributed to turbulence-induced transport. Although experimental results indicated that fluctuation-induced fluxes are significant in the edge plasma of these systems, it is not known whether the driving mechanisms or the origins of the turbulence are the same. Here, we compare the edge fluctuations and their associated transport by applying similar Langmuir probe diagnostics and analysis techniques to discharges in TEXT Tokamak, ATF Stellarator and ZT40M RFP. (author) 5 refs., 2 figs., 2 tabs.