Fractional Diffusion Equations and Anomalous Diffusion
Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin
2018-01-01
Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.
Diffusion coefficient for anomalous transport
International Nuclear Information System (INIS)
1986-01-01
A report on the progress towards the goal of estimating the diffusion coefficient for anomalous transport is given. The gyrokinetic theory is used to identify different time and length scale inherent to the characteristics of plasmas which exhibit anomalous transport
Anomalous diffusion in chaotic scattering
International Nuclear Information System (INIS)
Srokowski, T.; Ploszajczak, M.
1994-01-01
The anomalous diffusion is found for peripheral collision of atomic nuclei described in the framework of the molecular dynamics. Similarly as for chaotic billiards, the long free paths are the source of the long-time correlations and the anomalous diffusion. Consequences of this finding for the energy dissipation in deep-inelastic collisions and the dynamics of fission in hot nuclei are discussed (authors). 30 refs., 2 figs
Fractional diffusion equations and anomalous diffusion
Evangelista, Luiz Roberto
2018-01-01
Anomalous diffusion has been detected in a wide variety of scenarios, from fractal media, systems with memory, transport processes in porous media, to fluctuations of financial markets, tumour growth, and complex fluids. Providing a contemporary treatment of this process, this book examines the recent literature on anomalous diffusion and covers a rich class of problems in which surface effects are important, offering detailed mathematical tools of usual and fractional calculus for a wide audience of scientists and graduate students in physics, mathematics, chemistry and engineering. Including the basic mathematical tools needed to understand the rules for operating with the fractional derivatives and fractional differential equations, this self-contained text presents the possibility of using fractional diffusion equations with anomalous diffusion phenomena to propose powerful mathematical models for a large variety of fundamental and practical problems in a fast-growing field of research.
Multienergy anomalous diffuse scattering
Czech Academy of Sciences Publication Activity Database
Kopecký, Miloš; Fábry, Jan; Kub, Jiří; Lausi, A.; Busetto, E.
2008-01-01
Roč. 100, č. 19 (2008), 195504/1-195504/4 ISSN 0031-9007 R&D Projects: GA AV ČR IAA100100529 Institutional research plan: CEZ:AV0Z10100523 Keywords : diffuse scattering * x-rays * structure determination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.180, year: 2008
Anomalous diffusion of fermions in superlattices
International Nuclear Information System (INIS)
Drozdz, S.; Okolowicz, J.; Srokowski, T.; Ploszajczak, M.
1996-03-01
Diffusion of fermions in the periodic two-dimensional lattice of fermions is studied. It is shown that effects connected with antisymmetrization of the wave function increase chaoticness of motion. Various types of anomalous diffusion, characterized by a power spectral analysis are found. The nonlocality of the Pauli potential destroys cantori in the phase space. Consequently, the diffusion process is dominated by long free paths and the power spectrum is logarithmic at small frequency limit. (author)
Anomalous diffusion in a dynamical optical lattice
Zheng, Wei; Cooper, Nigel R.
2018-02-01
Motivated by experimental progress in strongly coupled atom-photon systems in optical cavities, we study theoretically the quantum dynamics of atoms coupled to a one-dimensional dynamical optical lattice. The dynamical lattice is chosen to have a period that is incommensurate with that of an underlying static lattice, leading to a dynamical version of the Aubry-André model which can cause localization of single-particle wave functions. We show that atomic wave packets in this dynamical lattice generically spread via anomalous diffusion, which can be tuned between superdiffusive and subdiffusive regimes. This anomalous diffusion arises from an interplay between Anderson localization and quantum fluctuations of the cavity field.
Anomalous diffusion spreads its wings
Energy Technology Data Exchange (ETDEWEB)
Klafter, J. [School of Chemistry, Tel Aviv University, Tel-Aviv (Israel)]. E-mail: klafter@post.tau.ac.il; Sokolov, I.M. [Institute of Physics, Humboldt University, Berlin (Germany)]. E-mail: igor.sokolov@physik.hu-berlin.de
2005-08-01
An increasing number of natural phenomena do not fit into the relatively simple description of diffusion developed by Einstein a century ago. As all of us are no doubt aware, this year has been declared 'world year of physics' to celebrate the three remarkable breakthroughs made by Albert Einstein in 1905. However, it is not so well known that Einstein's work on Brownian motion - the random motion of tiny particles first observed and investigated by the botanist Robert Brown in 1827 - has been cited more times in the scientific literature than his more famous papers on special relativity and the quantum nature of light. In a series of publications that included his doctoral thesis, Einstein derived an equation for Brownian motion from microscopic principles - a feat that ultimately enabled Jean Perrin and others to prove the existence of atoms (see 'Einstein's random walk' Physics World January pp19-22). Einstein was not the only person thinking about this type of problem. The 27 July 1905 issue of Nature contained a letter with the title 'The problem of the random walk' by the British statistician Karl Pearson, who was interested in the way that mosquitoes spread malaria, which he showed was described by the well-known diffusion equation. As such, the displacement of a mosquito from its initial position is proportional to the square root of time, and the distribution of the positions of many such 'random walkers' starting from the same origin is Gaussian in form. The random walk has since turned out to be intimately linked to Einstein's work on Brownian motion, and has become a major tool for understanding diffusive processes in nature. (U.K.)
Anomalous diffusion in geophysical and laboratory turbulence
Directory of Open Access Journals (Sweden)
A. Tsinober
1994-01-01
Full Text Available We present an overview and some new results on anomalous diffusion of passive scalar in turbulent flows (including those used by Richardson in his famous paper in 1926. The obtained results are based on the analysis of the properties of invariant quantities (energy, enstrophy, dissipation, enstrophy generation, helicity density, etc. - i.e. independent of the choice of the system of reference as the most appropriate to describe physical processes - in three different turbulent laboratory flows (grid-flow, jet and boundary layer, see Tsinober et al. (1992 and Kit et al. (1993. The emphasis is made on the relations between the asymptotic properties of the intermittency exponents of higher order moments of different turbulent fields (energy, dissipation, helicity, spontaneous breaking of isotropy and reflexional symmetry and the variability of turbulent diffusion in the atmospheric boundary layer, in the troposphere and in the stratosphere. It is argued that local spontaneous breaking of isotropy of turbulent flow results in anomalous scaling laws for turbulent diffusion (as compared to the scaling law of Richardson which are observed, as a rule, in different atmospheric layers from the atmospheric boundary layer (ABL to the stratosphere. Breaking of rotational symmetry is important in the ABL, whereas reflexional symmetry breaking is dominating in the troposphere locally and in the stratosphere globally. The results are of speculative nature and further analysis is necessary to validate or disprove the claims made, since the correspondence with the experimental results may occur for the wrong reasons as happens from time to time in the field of turbulence.
Anomalous water diffusion in salt solutions
Ding, Yun; Hassanali, Ali A.; Parrinello, Michele
2014-01-01
The dynamics of water exhibits anomalous behavior in the presence of different electrolytes. Recent experiments [Kim JS, Wu Z, Morrow AR, Yethiraj A, Yethiraj A (2012) J Phys Chem B 116(39):12007–12013] have found that the self-diffusion of water can either be enhanced or suppressed around CsI and NaCl, respectively, relative to that of neat water. Here we show that unlike classical empirical potentials, ab initio molecular dynamics simulations successfully reproduce the qualitative trends observed experimentally. These types of phenomena have often been rationalized in terms of the “structure-making” or “structure-breaking” effects of different ions on the solvent, although the microscopic origins of these features have remained elusive. Rather than disrupting the network in a significant manner, the electrolytes studied here cause rather subtle changes in both structural and dynamical properties of water. In particular, we show that water in the ab initio molecular dynamics simulations is characterized by dynamic heterogeneity, which turns out to be critical in reproducing the experimental trends. PMID:24522111
A variable-order fractal derivative model for anomalous diffusion
Directory of Open Access Journals (Sweden)
Liu Xiaoting
2017-01-01
Full Text Available This paper pays attention to develop a variable-order fractal derivative model for anomalous diffusion. Previous investigations have indicated that the medium structure, fractal dimension or porosity may change with time or space during solute transport processes, results in time or spatial dependent anomalous diffusion phenomena. Hereby, this study makes an attempt to introduce a variable-order fractal derivative diffusion model, in which the index of fractal derivative depends on temporal moment or spatial position, to characterize the above mentioned anomalous diffusion (or transport processes. Compared with other models, the main advantages in description and the physical explanation of new model are explored by numerical simulation. Further discussions on the dissimilitude such as computational efficiency, diffusion behavior and heavy tail phenomena of the new model and variable-order fractional derivative model are also offered.
Absolute negative mobility in the anomalous diffusion
Chen, Ruyin; Chen, Chongyang; Nie, Linru
2017-12-01
Transport of an inertial Brownian particle driven by the multiplicative Lévy noise was investigated here. Numerical results indicate that: (i) The Lévy noise is able to induce absolute negative mobility (ANM) in the system, while disappearing in the deterministic case; (ii) the ANM can occur in the region of superdiffusion while disappearing in the region of normal diffusion, and the appropriate stable index of the Lévy noise makes the particle move along the opposite direction of the bias force to the maximum degree; (iii) symmetry breaking of the Lévy noise also causes the ANM effect. In addition, the intrinsic physical mechanism and conditions for the ANM to occur are discussed in detail. Our results have the implication that the Lévy noise plays an important role in the occurrence of the ANM phenomenon.
Mechanisms underlying anomalous diffusion in the plasma membrane.
Krapf, Diego
2015-01-01
The plasma membrane is a complex fluid where lipids and proteins undergo diffusive motion critical to biochemical reactions. Through quantitative imaging analyses such as single-particle tracking, it is observed that diffusion in the cell membrane is usually anomalous in the sense that the mean squared displacement is not linear with time. This chapter describes the different models that are employed to describe anomalous diffusion, paying special attention to the experimental evidence that supports these models in the plasma membrane. We review models based on anticorrelated displacements, such as fractional Brownian motion and obstructed diffusion, and nonstationary models such as continuous time random walks. We also emphasize evidence for the formation of distinct compartments that transiently form on the cell surface. Finally, we overview heterogeneous diffusion processes in the plasma membrane, which have recently attracted considerable interest. Copyright © 2015. Published by Elsevier Inc.
Fractal diffusion equations: Microscopic models with anomalous diffusion and its generalizations
International Nuclear Information System (INIS)
Arkhincheev, V.E.
2001-04-01
To describe the ''anomalous'' diffusion the generalized diffusion equations of fractal order are deduced from microscopic models with anomalous diffusion as Comb model and Levy flights. It is shown that two types of equations are possible: with fractional temporal and fractional spatial derivatives. The solutions of these equations are obtained and the physical sense of these fractional equations is discussed. The relation between diffusion and conductivity is studied and the well-known Einstein relation is generalized for the anomalous diffusion case. It is shown that for Levy flight diffusion the Ohm's law is not applied and the current depends on electric field in a nonlinear way due to the anomalous character of Levy flights. The results of numerical simulations, which confirmed this conclusion, are also presented. (author)
The anomalous self-diffusion in α-Zr
International Nuclear Information System (INIS)
Hood, G.M.
1985-01-01
In a very recent publication, Horvath, Dyment and Mehrer, henceforth HDM, presented measurements of the self-diffusion coefficient Dsub(m) 0 for α-Zr as a function of temperature. The results of that study, done on a single crystal sample, were anomalous in the sense that a plot of log Dsub(m) 0 vs. 1/T(K -1 ) was not only non-linear, but exhibited two regions of downward curvature with increasing 1/T. HDM indicated that they were unable to see any explanation of their anomalous self-diffusion results. It is the purpose of this letter to indicate a means whereby these anomalous results may be ''explained'' and to suggest some experiments which might be undertaken to test the proposal. (orig./RK)
Anomalous fast diffusion in Cu-NiFe nanolaminates.
Energy Technology Data Exchange (ETDEWEB)
Jankowski, Alan F. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States). Energy Nanomaterials Dept.
2017-09-01
For this work, the decomposition of the one-dimensional composition wave in Cu-NiFe nanolaminate structures is examined using x-ray diffraction to assess the kinetics of phase decomposition. The anomalously high diffusivity value found for long-term aging at room temperature is attributed to the inherent nanostructure that features paths for short-circuit diffusion in nanolaminates as attributed to interlayer grain boundaries.
Anomalous diffusion in a symbolic model
International Nuclear Information System (INIS)
Ribeiro, H V; Lenzi, E K; Mendes, R S; Santoro, P A
2011-01-01
In this work, we investigate some statistical properties of symbolic sequences generated by a numerical procedure in which the symbols are repeated following the power-law probability density. In this analysis, we consider that the sum of n symbols represents the position of a particle in erratic movement. This approach reveals a rich diffusive scenario characterized by non-Gaussian distribution and, depending on the power-law exponent or the procedure used to build the walker, we may have superdiffusion, subdiffusion or usual diffusion. Additionally, we use the continuous-time random walk framework to compare the analytic results with the numerical data, thereby finding good agreement. Because of its simplicity and flexibility, this model can be a candidate for describing real systems governed by power-law probability densities.
Path Integral Formulation of Anomalous Diffusion Processes
Friedrich, Rudolf; Eule, Stephan
2011-01-01
We present the path integral formulation of a broad class of generalized diffusion processes. Employing the path integral we derive exact expressions for the path probability densities and joint probability distributions for the class of processes under consideration. We show that Continuous Time Random Walks (CTRWs) are included in our framework. A closed expression for the path probability distribution of CTRWs is found in terms of their waiting time distribution as the solution of a Dyson ...
Anomalous Transport of Cosmic Rays in a Nonlinear Diffusion Model
Energy Technology Data Exchange (ETDEWEB)
Litvinenko, Yuri E. [Department of Mathematics, University of Waikato, P. B. 3105, Hamilton 3240 (New Zealand); Fichtner, Horst; Walter, Dominik [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum (Germany)
2017-05-20
We investigate analytically and numerically the transport of cosmic rays following their escape from a shock or another localized acceleration site. Observed cosmic-ray distributions in the vicinity of heliospheric and astrophysical shocks imply that anomalous, superdiffusive transport plays a role in the evolution of the energetic particles. Several authors have quantitatively described the anomalous diffusion scalings, implied by the data, by solutions of a formal transport equation with fractional derivatives. Yet the physical basis of the fractional diffusion model remains uncertain. We explore an alternative model of the cosmic-ray transport: a nonlinear diffusion equation that follows from a self-consistent treatment of the resonantly interacting cosmic-ray particles and their self-generated turbulence. The nonlinear model naturally leads to superdiffusive scalings. In the presence of convection, the model yields a power-law dependence of the particle density on the distance upstream of the shock. Although the results do not refute the use of a fractional advection–diffusion equation, they indicate a viable alternative to explain the anomalous diffusion scalings of cosmic-ray particles.
Anomalous diffusion on 2d randomly oriented diode networks
International Nuclear Information System (INIS)
Aydiner, E.; Kiymach, K.
2002-01-01
In this work, we have studied the diffusion properties of a randomly oriented two- dimensional diode network, using Monte Carlo Simulation method. The characteristic exponent α of the diffusion is obtained against the reverse transition probability W γ . We have found two critical values of W γ ; 0.003 and 0.4. α has been found to be 0.376 for W γ ≤ 0.003, and ≅ 1 for W γ ≥ 0.4 . For W γ >0.4 normal diffusion, and for 0.003≤W γ ≤0.4 anomalous sub-diffusion are observed. But for W γ ≤0.003 there seems to be no diffusion at all
Anomalous diffusion in niobium. Study of solute diffusion mechanism of iron in niobium
International Nuclear Information System (INIS)
Ablitzer, D.
1977-01-01
In order to explain anomalously high diffusion velocities observed for iron diffusion in niobium, the following parameters were measured: isotope effect, b factor (which expresses the effect of iron on niobium self-diffusion), self-diffusion coefficient of niobium, solute diffusion coefficient of iron in niobium. The results obtained show that neither pure vacancy models, nor diffusion in the lattice defects (dislocations, sub-boundaries, grain boundaries), nor pure interstitialy mechanisms, nor simple or cyclic exchange mechanisms agree with experiments. A mechanism is proposed which considers an equilibrium between substitution iron atoms and interstitial iron atoms. The diffusion of iron then occurs through interstitial vancancy pairs [fr
Anomalous transport regimes in a stochastic advection-diffusion model
International Nuclear Information System (INIS)
Dranikov, I.L.; Kondratenko, P.S.; Matveev, L.V.
2004-01-01
A general solution to the stochastic advection-diffusion problem is obtained for a fractal medium with long-range correlated spatial fluctuations. A particular transport regime is determined by two basic parameters: the exponent 2h of power-law decay of the two-point velocity correlation function and the mean advection velocity u. The values of these parameters corresponding to anomalous diffusion are determined, and anomalous behavior of the tracer distribution is analyzed for various combinations of u and h. The tracer concentration is shown to decrease exponentially at large distances, whereas power-law decay is predicted by fractional differential equations. Equations that describe the essential characteristics of the solution are written in terms of coupled space-time fractional differential operators. The analysis relies on a diagrammatic technique and makes use of scale-invariant properties of the medium
A fractional Fokker-Planck model for anomalous diffusion
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Anderson, Johan, E-mail: anderson.johan@gmail.com [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Kim, Eun-jin [Department of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Moradi, Sara [Ecole Polytechnique, CNRS UMR7648, LPP, F-91128 Palaiseau (France)
2014-12-15
In this paper, we present a study of anomalous diffusion using a Fokker-Planck description with fractional velocity derivatives. The distribution functions are found using numerical means for varying degree of fractionality of the stable Lévy distribution. The statistical properties of the distribution functions are assessed by a generalized normalized expectation measure and entropy in terms of Tsallis statistical mechanics. We find that the ratio of the generalized entropy and expectation is increasing with decreasing fractionality towards the well known so-called sub-diffusive domain, indicating a self-organising behavior.
Self-similar anomalous diffusion and Levy-stable laws
International Nuclear Information System (INIS)
Uchaikin, Vladimir V
2003-01-01
Stochastic principles for constructing the process of anomalous diffusion are considered, and corresponding models of random processes are reviewed. The self-similarity and the independent-increments principles are used to extend the notion of diffusion process to the class of Levy-stable processes. Replacing the independent-increments principle with the renewal principle allows us to take the next step in generalizing the notion of diffusion, which results in fractional-order partial space-time differential equations of diffusion. Fundamental solutions to these equations are represented in terms of stable laws, and their relationship to the fractality and memory of the medium is discussed. A new class of distributions, called fractional stable distributions, is introduced. (reviews of topical problems)
Asymptotic neutron scattering laws for anomalously diffusing quantum particles
Energy Technology Data Exchange (ETDEWEB)
Kneller, Gerald R. [Centre de Biophysique Moléculaire, CNRS, Rue Charles Sadron, 45071 Orléans (France); Université d’Orléans, Chateau de la Source-Ave. du Parc Floral, 45067 Orléans (France); Synchrotron-SOLEIL, L’Orme de Merisiers, 91192 Gif-sur-Yvette (France)
2016-07-28
The paper deals with a model-free approach to the analysis of quasielastic neutron scattering intensities from anomalously diffusing quantum particles. All quantities are inferred from the asymptotic form of their time-dependent mean square displacements which grow ∝t{sup α}, with 0 ≤ α < 2. Confined diffusion (α = 0) is here explicitly included. We discuss in particular the intermediate scattering function for long times and the Fourier spectrum of the velocity autocorrelation function for small frequencies. Quantum effects enter in both cases through the general symmetry properties of quantum time correlation functions. It is shown that the fractional diffusion constant can be expressed by a Green-Kubo type relation involving the real part of the velocity autocorrelation function. The theory is exact in the diffusive regime and at moderate momentum transfers.
Lin, Guoxing
2018-05-01
Anomalous diffusion exists widely in polymer and biological systems. Pulsed-field gradient (PFG) anomalous diffusion is complicated, especially in the anisotropic case where limited research has been reported. A general PFG signal attenuation expression, including the finite gradient pulse (FGPW) effect for free general anisotropic fractional diffusion { 0 integral modified-Bloch equation, were extended to obtain general PFG signal attenuation expressions for anisotropic anomalous diffusion. Various cases of PFG anisotropic anomalous diffusion were investigated, including coupled and uncoupled anisotropic anomalous diffusion. The continuous-time random walk (CTRW) simulation was also carried out to support the theoretical results. The theory and the CTRW simulation agree with each other. The obtained signal attenuation expressions and the three-dimensional fractional modified-Bloch equations are important for analyzing PFG anisotropic anomalous diffusion in NMR and MRI.
Simulations of anomalous ion diffusion in experimentally measured turbulent potential
Czech Academy of Sciences Publication Activity Database
Seidl, Jakub; Krlín, Ladislav; Pánek, Radomír; Pavlo, Pavol; Stöckel, Jan; Svoboda, V.
2009-01-01
Roč. 54, č. 2 (2009), s. 399-407 ISSN 1434-6060. [Symposium on Plasma Physics and Technology/23rd./. Prague, 16.06.2008-19.06.2008] R&D Projects: GA ČR GA202/07/0044; GA AV ČR IAA100430502 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma turbulence * Lévy-walk * anomalous diffusion * plasma impurities Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.420, year: 2009 http://www.springerlink.com/content/hn8041u48795847m/
Reversible island nucleation and growth with anomalous diffusion
Sabbar, Ehsan H.; Amar, Jacques G.
2017-10-01
Motivated by recent experiments on submonolayer organic film growth with anomalous diffusion, a general rate-equation (RE) theory of submonolayer island nucleation and growth was developed (Amar and Semaan, 2016) [23], which takes into account the critical island-size i, island fractal dimension df, substrate dimension d, and diffusion exponent μ, and good agreement with simulations was found for the case of irreversible growth corresponding to a critical island-size i = 1 with d = 2 . However, since many experiments correspond to a critical island-size larger than 1, it is of interest to determine if the RE predictions also hold in the case of reversible island nucleation with anomalous diffusion. Here we present the results of simulations of submonolayer growth with i = 2 (d = 2) which were carried out for both the case of superdiffusion (μ > 1) and subdiffusion (μ deposited monomers, excellent agreement is obtained with the predictions of the generalized RE theory for the exponents χ(μ) and χ1(μ) which describe the dependence of the island and monomer densities at fixed coverage on deposition rate F. In addition, the exponents do not depend on whether or not monomers remain superdiffusive or are thermalized (e.g. undergo regular diffusion) after detaching from a dimer. However, we also find that, as was previously found in the case of irreversible growth, the exponent χ only approaches its asymptotic value logarithmically with increasing 1/F. This result has important implications for the interpretation of experiments. Good agreement with the RE theory is also found in the case of subdiffusion for point-islands. However, in the case of ramified islands with subdiffusion and i = 2 , the exponents are significantly higher than predicted due to the fact that monomer capture dominates in the nucleation regime. A modified RE theory which takes this into account is presented, and excellent agreement is found with our simulations.
Superstatistical generalised Langevin equation: non-Gaussian viscoelastic anomalous diffusion
Ślęzak, Jakub; Metzler, Ralf; Magdziarz, Marcin
2018-02-01
Recent advances in single particle tracking and supercomputing techniques demonstrate the emergence of normal or anomalous, viscoelastic diffusion in conjunction with non-Gaussian distributions in soft, biological, and active matter systems. We here formulate a stochastic model based on a generalised Langevin equation in which non-Gaussian shapes of the probability density function and normal or anomalous diffusion have a common origin, namely a random parametrisation of the stochastic force. We perform a detailed analysis demonstrating how various types of parameter distributions for the memory kernel result in exponential, power law, or power-log law tails of the memory functions. The studied system is also shown to exhibit a further unusual property: the velocity has a Gaussian one point probability density but non-Gaussian joint distributions. This behaviour is reflected in the relaxation from a Gaussian to a non-Gaussian distribution observed for the position variable. We show that our theoretical results are in excellent agreement with stochastic simulations.
A tutorial on inverse problems for anomalous diffusion processes
International Nuclear Information System (INIS)
Jin, Bangti; Rundell, William
2015-01-01
Over the last two decades, anomalous diffusion processes in which the mean squares variance grows slower or faster than that in a Gaussian process have found many applications. At a macroscopic level, these processes are adequately described by fractional differential equations, which involves fractional derivatives in time or/and space. The fractional derivatives describe either history mechanism or long range interactions of particle motions at a microscopic level. The new physics can change dramatically the behavior of the forward problems. For example, the solution operator of the time fractional diffusion diffusion equation has only limited smoothing property, whereas the solution for the space fractional diffusion equation may contain weak singularity. Naturally one expects that the new physics will impact related inverse problems in terms of uniqueness, stability, and degree of ill-posedness. The last aspect is especially important from a practical point of view, i.e., stably reconstructing the quantities of interest. In this paper, we employ a formal analytic and numerical way, especially the two-parameter Mittag-Leffler function and singular value decomposition, to examine the degree of ill-posedness of several ‘classical’ inverse problems for fractional differential equations involving a Djrbashian–Caputo fractional derivative in either time or space, which represent the fractional analogues of that for classical integral order differential equations. We discuss four inverse problems, i.e., backward fractional diffusion, sideways problem, inverse source problem and inverse potential problem for time fractional diffusion, and inverse Sturm–Liouville problem, Cauchy problem, backward fractional diffusion and sideways problem for space fractional diffusion. It is found that contrary to the wide belief, the influence of anomalous diffusion on the degree of ill-posedness is not definitive: it can either significantly improve or worsen the conditioning
Polymer translocation through a nanopore: a showcase of anomalous diffusion.
Milchev, A; Dubbeldam, Johan L A; Rostiashvili, Vakhtang G; Vilgis, Thomas A
2009-04-01
We investigate the translocation dynamics of a polymer chain threaded through a membrane nanopore by a chemical potential gradient that acts on the chain segments inside the pore. By means of diverse methods (scaling theory, fractional calculus, and Monte Carlo and molecular dynamics simulations), we demonstrate that the relevant dynamic variable, the transported number of polymer segments, s(t), displays an anomalous diffusive behavior, both with and without an external driving force being present. We show that in the absence of drag force the time tau, needed for a macromolecule of length N to thread from the cis into the trans side of a cell membrane, scales as tauN(2/alpha) with the chain length. The anomalous dynamics of the translocation process is governed by a universal exponent alpha= 2/(2nu + 2 - gamma(1)), which contains the basic universal exponents of polymer physics, nu (the Flory exponent) and gamma(1) (the surface entropic exponent). A closed analytic expression for the probability to find s translocated segments at time t in terms of chain length N and applied drag force f is derived from the fractional Fokker-Planck equation, and shown to provide analytic results for the time variation of the statistical moments and . It turns out that the average translocation time scales as tau proportional, f(-1)N(2/alpha-1). These results are tested and found to be in perfect agreement with extensive Monte Carlo and molecular dynamics computer simulations.
Modeling of 1D Anomalous Diffusion in Fractured Nanoporous Media
Directory of Open Access Journals (Sweden)
Albinali Ali
2016-07-01
Full Text Available Fractured nanoporous reservoirs include multi-scale and discontinuous fractures coupled with a complex nanoporous matrix. Such systems cannot be described by the conventional dual-porosity (or multi-porosity idealizations due to the presence of different flow mechanisms at multiple scales. More detailed modeling approaches, such as Discrete Fracture Network (DFN models, similarly suffer from the extensive data requirements dictated by the intricacy of the flow scales, which eventually deter the utility of these models. This paper discusses the utility and construction of 1D analytical and numerical anomalous diffusion models for heterogeneous, nanoporous media, which is commonly encountered in oil and gas production from tight, unconventional reservoirs with fractured horizontal wells. A fractional form of Darcy’s law, which incorporates the non-local and hereditary nature of flow, is coupled with the classical mass conservation equation to derive a fractional diffusion equation in space and time. Results show excellent agreement with established solutions under asymptotic conditions and are consistent with the physical intuitions.
Trapped ion depletion by anomalous diffusion due to the dissipative trapped ion instability
International Nuclear Information System (INIS)
Wimmel, H.K.
1975-07-01
At high temperatures the KADOMTSEV-POGUTSE diffusion in tokamaks can become so large as to cause depletion of trapped ions if these are replaced with free ions by means of collisions rather than being directly recycled or injected. Modified KADOMTSEV-POGUTSE diffusion formulas are employed in order to estimate this effect in the cases of classical and anomalous collisions. The maximum trapped-ion depletion is estimated from the PENROSE stability condition. For anomalous collisions a BOHM-type diffusion is derived. Numerical examples are given for JET-like parameters (JET = Joint European Torus). Depletion is found to reduce diffusion by factors of up to 10 and more. (orig.) [de
A new model of anomalous phosphorus diffusion in silicon
International Nuclear Information System (INIS)
Budil, M.; Poetzl, H.; Stingeder, G.; Grasserbauer, M.
1989-01-01
A model is presented to describe the 'kink and tail' diffusion of phosphorus. The diffusion behaviour of phosphorus is expplained by the motion of phosphorus-interstitial and phosphorus-vacancy pairs in different charge states. The model yields the enhancement of diffusion in the tail region depending on surface concentration. Furthermore it yields the same selfdiffusion coefficient for interstitials as the gold diffusion experiments. A transformation of the diffusion equation was found to reduce the number of simulation equations. (author) 7 refs., 5 figs
On mean square displacement behaviors of anomalous diffusions with variable and random orders
International Nuclear Information System (INIS)
Sun Hongguang; Chen Wen; Sheng Hu; Chen Yangquan
2010-01-01
Mean square displacement (MSD) is used to characterize anomalous diffusion. Recently, models of anomalous diffusion with variable-order and random-order were proposed, but no MSD analysis has been given so far. The purpose of this Letter is to offer a concise derivation of MSD functions for the variable-order model and the random-order model. Numerical results are presented to illustrate the analytical results. In addition, we show how to establish a variable-random-order model for a given MSD function which has clear application potentials.
International Nuclear Information System (INIS)
Maleki Moghaddam, Nader; Afarideh, Hossein; Espinosa-Paredes, Gilberto
2015-01-01
Highlights: • The new version of neutron diffusion equation for simulating anomalous diffusion is presented. • Application of fractional calculus in the nuclear reactor is revealed. • A 3D-Multigroup program is developed based on the fractional operators. • The super-diffusion and sub-diffusion phenomena are modeled in the nuclear reactors core. - Abstract: The diffusion process is categorized in three parts, normal diffusion, super-diffusion and sub-diffusion. The classical neutron diffusion equation is used to model normal diffusion. A new scheme of derivatives is required to model anomalous diffusion phenomena. The fractional space derivatives are employed to model anomalous diffusion processes where a plume of particles spreads at an inconsistent rate with the classical Brownian motion model. In the fractional diffusion equation, the fractional Laplacians are used; therefore the statistical jump length of neutrons is unrestricted. It is clear that the fractional Laplacians are capable to model the anomalous phenomena in nuclear reactors. We have developed a NFDE-3D (neutron fractional diffusion equation) as a core calculation code to model normal and anomalous diffusion phenomena. The NFDE-3D is validated against the LMW-LWR reactor. The results demonstrate that reactors exhibit complex behavior versus order of the fractional derivatives which depends on the competition between neutron absorption and super-diffusion phenomenon
Anomalous behavior of the diffusion coefficient in thin active films
International Nuclear Information System (INIS)
Basu, Abhik; Joanny, Jean-Francois; Prost, Jacques; Jülicher, Frank
2012-01-01
Inspired by recent experiments in cell biology, we elucidate the visco-elastic properties of an active gel by studying the dynamics of a small tracer particle inside it. In a stochastic hydrodynamic approach for an active gel of finite thickness L, we calculate the mean square displacement of a particle. These particle displacements are governed by fluctuations in the velocity field. We characterize the short-time behavior when the gel is a solid as well as the limit of long times when the gel becomes a fluid and the particle shows simple diffusion. Active stresses together with local polar order give rise to velocity fluctuations that lead to characteristic behaviors of the diffusion coefficient that differ fundamentally from those found in a passive system: the diffusion coefficient can depend on system size and diverges as L approaches an instability threshold. Furthermore, the diffusion coefficient becomes independent of the particle size in this case. (paper)
Ohm's law in turbulent plasmas and beta limitations by anomalous diffusion
International Nuclear Information System (INIS)
Borrass, K.
1978-01-01
For axisymmetric diffusive equilibria a condition is derived by means of a generalized Ohm's law. It relates some effective outward particle flux to the toroidal current density. An approximate version of it requires that the corresponding effective diffusion velocity Vsub(D)sup(*) must not exceed the poloidal magnetic diffusion velocity Vsub(m). The simple version of Ohm's law as used in transport calculations only applies if Vsub(D)sup(*)<< Vsub(m). A preliminary discussion is performed for the case of anomalous diffusion due to trapped particle instabilities. (author)
Magdziarz, M.; Mista, P.; Weron, A.
2007-05-01
We introduce an approximation of the risk processes by anomalous diffusion. In the paper we consider the case, where the waiting times between successive occurrences of the claims belong to the domain of attraction of alpha -stable distribution. The relationship between the obtained approximation and the celebrated fractional diffusion equation is emphasised. We also establish upper bounds for the ruin probability in the considered model and give some numerical examples.
López-Sánchez, Erick J.; Romero, Juan M.; Yépez-Martínez, Huitzilin
2017-09-01
Different experimental studies have reported anomalous diffusion in brain tissues and notably this anomalous diffusion is expressed through fractional derivatives. Axons are important to understand neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, and Parkinson's disease. Indeed, abnormal accumulation of proteins and organelles in axons is a hallmark of these diseases. The diffusion in the axons can become anomalous as a result of this abnormality. In this case the voltage propagation in axons is affected. Another hallmark of different neurodegenerative diseases is given by discrete swellings along the axon. In order to model the voltage propagation in axons with anomalous diffusion and swellings, in this paper we propose a fractional cable equation for a general geometry. This generalized equation depends on fractional parameters and geometric quantities such as the curvature and torsion of the cable. For a cable with a constant radius we show that the voltage decreases when the fractional effect increases. In cables with swellings we find that when the fractional effect or the swelling radius increases, the voltage decreases. Similar behavior is obtained when the number of swellings and the fractional effect increase. Moreover, we find that when the radius swelling (or the number of swellings) and the fractional effect increase at the same time, the voltage dramatically decreases.
TRANSIENT ANOMALOUS SUB-DIFFUSION ON BOUNDED DOMAINS
MEERSCHAERT, MARK M.; NANE, ERKAN; VELLAISAMY, P.
2012-01-01
This paper develops strong solutions and stochastic solutions for the tempered fractional diffusion equation on bounded domains. First the eigenvalue problem for tempered fractional derivatives is solved. Then a separation of variables, and eigenfunction expansions in time and space, are used to write strong solutions. Finally, stochastic solutions are written in terms of an inverse subordinator.
International Nuclear Information System (INIS)
Helander, P.; Hazeltine, R.D.; Catto, P.J.
1996-01-01
The orderings in the kinetic equations commonly used to study the plasma core of a tokamak do not allow a balance between parallel ion streaming and radial diffusion, and are, therefore, inappropriate in the plasma edge. Different orderings are required in the edge region where radial transport across the steep gradients associated with the scrape-off layer is large enough to balance the rapid parallel flow caused by conditions close to collecting surfaces (such as the Bohm sheath condition). In the present work, we derive and solve novel kinetic equations, allowing for such a balance, and construct distinctive transport laws for impure, collisional, edge plasmas in which the perpendicular transport is (i) due to Coulomb collisions of ions with heavy impurities, or (ii) governed by anomalous diffusion driven by electrostatic turbulence. In both the collisional and anomalous radial transport cases, we find that one single diffusion coefficient determines the radial transport of particles, momentum and heat. The parallel transport laws and parallel thermal force in the scrape-off layer assume an unconventional form, in which the relative ion-impurity flow is driven by a combination of the conventional parallel gradients, and new (i) collisional or (ii) anomalous terms involving products of radial derivatives of the temperature and density with the radial shear of the parallel velocity. Thus, in the presence of anomalous radial diffusion, the parallel ion transport cannot be entirely classical, as usually assumed in numerical edge computations. The underlying physical reason is the appearance of a novel type of parallel thermal force resulting from the combined action of anomalous diffusion and radial temperature and velocity gradients. In highly sheared flows the new terms can modify impurity penetration into the core plasma
Magin, Richard L.; Akpa, Belinda S.; Neuberger, Thomas; Webb, Andrew G.
2011-12-01
We report the appearance of anomalous water diffusion in hydrophilic Sephadex gels observed using pulse field gradient (PFG) nuclear magnetic resonance (NMR). The NMR diffusion data was collected using a Varian 14.1 Tesla imaging system with a home-built RF saddle coil. A fractional order analysis of the data was used to characterize heterogeneity in the gels for the dynamics of water diffusion in this restricted environment. Several recent studies of anomalous diffusion have used the stretched exponential function to model the decay of the NMR signal, i.e., exp[-( bD) α], where D is the apparent diffusion constant, b is determined the experimental conditions (gradient pulse separation, durations and strength), and α is a measure of structural complexity. In this work, we consider a different case where the spatial Laplacian in the Bloch-Torrey equation is generalized to a fractional order model of diffusivity via a complexity parameter, β, a space constant, μ, and a diffusion coefficient, D. This treatment reverts to the classical result for the integer order case. The fractional order decay model was fit to the diffusion-weighted signal attenuation for a range of b-values (0 < b < 4000 s mm -2). Throughout this range of b values, the parameters β, μ and D, were found to correlate with the porosity and tortuosity of the gel structure.
Decoherence and quantum walks: Anomalous diffusion and ballistic tails
International Nuclear Information System (INIS)
Prokof'ev, N. V.; Stamp, P. C. E.
2006-01-01
The common perception is that strong coupling to the environment will always render the evolution of the system density matrix quasiclassical (in fact, diffusive) in the long time limit. We present here a counterexample, in which a particle makes quantum transitions between the sites of a d-dimensional hypercubic lattice while strongly coupled to a bath of two-level systems that 'record' the transitions. The long-time evolution of an initial wave packet is found to be most unusual: the mean square displacement of the particle density matrix shows long-range ballistic behavior, with 2 >∼t 2 , but simultaneously a kind of weakly localized behavior near the origin. This result may have important implications for the design of quantum computing algorithms, since it describes a class of quantum walks
Anomalous diffusion in neutral evolution of model proteins
Nelson, Erik D.; Grishin, Nick V.
2015-06-01
Protein evolution is frequently explored using minimalist polymer models, however, little attention has been given to the problem of structural drift, or diffusion. Here, we study neutral evolution of small protein motifs using an off-lattice heteropolymer model in which individual monomers interact as low-resolution amino acids. In contrast to most earlier models, both the length and folded structure of the polymers are permitted to change. To describe structural change, we compute the mean-square distance (MSD) between monomers in homologous folds separated by n neutral mutations. We find that structural change is episodic, and, averaged over lineages (for example, those extending from a single sequence), exhibits a power-law dependence on n . We show that this exponent depends on the alignment method used, and we analyze the distribution of waiting times between neutral mutations. The latter are more disperse than for models required to maintain a specific fold, but exhibit a similar power-law tail.
The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion
Energy Technology Data Exchange (ETDEWEB)
Guo, Ran; Du, Jiulin, E-mail: jiulindu@aliyun.com
2015-08-15
We study the time behavior of the Fokker–Planck equation in Zwanzig’s rule (the backward-Ito’s rule) based on the Langevin equation of Brownian motion with an anomalous diffusion in a complex medium. The diffusion coefficient is a function in momentum space and follows a generalized fluctuation–dissipation relation. We obtain the precise time-dependent analytical solution of the Fokker–Planck equation and at long time the solution approaches to a stationary power-law distribution in nonextensive statistics. As a test, numerically we have demonstrated the accuracy and validity of the time-dependent solution. - Highlights: • The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion is found. • The anomalous diffusion satisfies a generalized fluctuation–dissipation relation. • At long time the time-dependent solution approaches to a power-law distribution in nonextensive statistics. • Numerically we have demonstrated the accuracy and validity of the time-dependent solution.
The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion
International Nuclear Information System (INIS)
Guo, Ran; Du, Jiulin
2015-01-01
We study the time behavior of the Fokker–Planck equation in Zwanzig’s rule (the backward-Ito’s rule) based on the Langevin equation of Brownian motion with an anomalous diffusion in a complex medium. The diffusion coefficient is a function in momentum space and follows a generalized fluctuation–dissipation relation. We obtain the precise time-dependent analytical solution of the Fokker–Planck equation and at long time the solution approaches to a stationary power-law distribution in nonextensive statistics. As a test, numerically we have demonstrated the accuracy and validity of the time-dependent solution. - Highlights: • The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion is found. • The anomalous diffusion satisfies a generalized fluctuation–dissipation relation. • At long time the time-dependent solution approaches to a power-law distribution in nonextensive statistics. • Numerically we have demonstrated the accuracy and validity of the time-dependent solution
Liang, Yingjie; Ye, Allen Q.; Chen, Wen; Gatto, Rodolfo G.; Colon-Perez, Luis; Mareci, Thomas H.; Magin, Richard L.
2016-10-01
Non-Gaussian (anomalous) diffusion is wide spread in biological tissues where its effects modulate chemical reactions and membrane transport. When viewed using magnetic resonance imaging (MRI), anomalous diffusion is characterized by a persistent or 'long tail' behavior in the decay of the diffusion signal. Recent MRI studies have used the fractional derivative to describe diffusion dynamics in normal and post-mortem tissue by connecting the order of the derivative with changes in tissue composition, structure and complexity. In this study we consider an alternative approach by introducing fractal time and space derivatives into Fick's second law of diffusion. This provides a more natural way to link sub-voxel tissue composition with the observed MRI diffusion signal decay following the application of a diffusion-sensitive pulse sequence. Unlike previous studies using fractional order derivatives, here the fractal derivative order is directly connected to the Hausdorff fractal dimension of the diffusion trajectory. The result is a simpler, computationally faster, and more direct way to incorporate tissue complexity and microstructure into the diffusional dynamics. Furthermore, the results are readily expressed in terms of spectral entropy, which provides a quantitative measure of the overall complexity of the heterogeneous and multi-scale structure of biological tissues. As an example, we apply this new model for the characterization of diffusion in fixed samples of the mouse brain. These results are compared with those obtained using the mono-exponential, the stretched exponential, the fractional derivative, and the diffusion kurtosis models. Overall, we find that the order of the fractal time derivative, the diffusion coefficient, and the spectral entropy are potential biomarkers to differentiate between the microstructure of white and gray matter. In addition, we note that the fractal derivative model has practical advantages over the existing models from the
Martelloni, Gianluca; Bagnoli, Franco
2016-04-01
In the past three decades, fractional and fractal calculus (that is, calculus of derivatives and integral of any arbitrary real or complex order) appeared to be an important tool for its applications in many fields of science and engineering. This theory allows to face, analytically and/or numerically, fractional differential equations and fractional partial differential equations. In particular, one of the several applications deals with anomalous diffusion processes. The latter phenomena can be clearly described from the statistical viewpoint. Indeed, in various complex systems, the diffusion processes usually no longer follow Gaussian statistics, and thus Fick's second law fails to describe the related transport behavior. In particular, one observes deviations from the linear time dependence of the mean squared displacement ⟨x2(t)⟩ ∝ t, (1) which is characteristic of Brownian motion, i.e., a direct consequence of the central limit theorem and the Markovian nature of the underlying stochastic process [1-17]. Instead, anomalous diffusion is found in a wide diversity of systems and its feature is the non-linear growth of the mean squared displacement over time. Especially the power-law pattern, with exponent γ different from 1 ⟨ ⟩ x2(t) ∝ tγ, (2) characterizes many systems [18, 19], but a variety of other rules, such as a logarithmic time dependence, exist [20]. The anomalous diffusion, as expressed in Eq. (2) is connected with the breakdown of the central limit theorem, caused by either broad distributions or long-range correlations, e.g., the extreme statistics and the power law distributions, typical of the self-organized criticality [42, 43]. Instead, anomalous diffusion rests on the validity of the Levy-Gnedenko generalized central limit theorem [21-23]. Particularly, broad spatial jumps or waiting time distributions lead to non-Gaussian distribution and non-Markovian time evolution of the system. Anomalous diffusion has been known since
International Nuclear Information System (INIS)
Khorrami, Mohammad; Shariati, Ahmad; Aghamohammadi, Amir; Fatollahi, Amir H.
2012-01-01
It is shown that as far as the linear diffusion equation meets both time- and space-translational invariance, the time dependence of a moment of degree α is a polynomial of degree at most equal to α, while all connected moments are at most linear functions of time. As a special case, the variance is an at most linear function of time. -- Highlights: ► The sufficient conditions for having the non-anomalous diffusion are given. ► Conditions are linearity, space-time translation invariance, solution uniqueness. ► Some versions of the fractional derivatives lack the translational invariance. ► It is shown the encoded inhomogeneity in derivatives causes anomalous behavior.
Energy Technology Data Exchange (ETDEWEB)
Khorrami, Mohammad, E-mail: mamwad@mailaps.org [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of); Shariati, Ahmad, E-mail: shariati@mailaps.org [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of); Aghamohammadi, Amir, E-mail: mohamadi@alzahra.ac.ir [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of); Fatollahi, Amir H., E-mail: ahfatol@gmail.com [Department of Physics, Alzahra University, Tehran 19938-93973 (Iran, Islamic Republic of)
2012-01-16
It is shown that as far as the linear diffusion equation meets both time- and space-translational invariance, the time dependence of a moment of degree α is a polynomial of degree at most equal to α, while all connected moments are at most linear functions of time. As a special case, the variance is an at most linear function of time. -- Highlights: ► The sufficient conditions for having the non-anomalous diffusion are given. ► Conditions are linearity, space-time translation invariance, solution uniqueness. ► Some versions of the fractional derivatives lack the translational invariance. ► It is shown the encoded inhomogeneity in derivatives causes anomalous behavior.
Anomalous dimension in a two-species reaction-diffusion system
Vollmayr-Lee, Benjamin; Hanson, Jack; McIsaac, R. Scott; Hellerick, Joshua D.
2018-01-01
We study a two-species reaction-diffusion system with the reactions A+A\\to (0, A) and A+B\\to A , with general diffusion constants D A and D B . Previous studies showed that for dimensions d≤slant 2 the B particle density decays with a nontrivial, universal exponent that includes an anomalous dimension resulting from field renormalization. We demonstrate via renormalization group methods that the scaled B particle correlation function has a distinct anomalous dimension resulting in the asymptotic scaling \\tilde CBB(r, t) ˜ tφf(r/\\sqrt{t}) , where the exponent ϕ results from the renormalization of the square of the field associated with the B particles. We compute this exponent to first order in \
In vivo Anomalous Diffusion and Weak Ergodicity Breaking of Lipid Granules
DEFF Research Database (Denmark)
Jeon, J.-H.; Tejedor, V.; Burov, S.
2011-01-01
Combining extensive single particle tracking microscopy data of endogenous lipid granules in living fission yeast cells with analytical results we show evidence for anomalous diffusion and weak ergodicity breaking. Namely we demonstrate that at short times the granules perform subdiffusion...... according to the laws of continuous time random walk theory. The associated violation of ergodicity leads to a characteristic turnover between two scaling regimes of the time averaged mean squared displacement. At longer times the granule motion is consistent with fractional Brownian motion....
A new fractional operator of variable order: Application in the description of anomalous diffusion
Yang, Xiao-Jun; Machado, J. A. Tenreiro
2017-09-01
In this paper, a new fractional operator of variable order with the use of the monotonic increasing function is proposed in sense of Caputo type. The properties in term of the Laplace and Fourier transforms are analyzed and the results for the anomalous diffusion equations of variable order are discussed. The new formulation is efficient in modeling a class of concentrations in the complex transport process.
Berry, Hugues; Chaté, Hugues
2014-02-01
In vivo measurements of the passive movements of biomolecules or vesicles in cells consistently report "anomalous diffusion," where mean-squared displacements scale as a power law of time with exponent αmovement hindrance by obstacles is often invoked. However, our understanding of how hindered diffusion leads to subdiffusion is based on diffusion amidst randomly located immobile obstacles. Here, we have used Monte Carlo simulations to investigate transient subdiffusion due to mobile obstacles with various modes of mobility. Our simulations confirm that the anomalous regimes rapidly disappear when the obstacles move by Brownian motion. By contrast, mobile obstacles with more confined displacements, e.g., Orstein-Ulhenbeck motion, are shown to preserve subdiffusive regimes. The mean-squared displacement of tracked protein displays convincing power laws with anomalous exponent α that varies with the density of Orstein-Ulhenbeck (OU) obstacles or the relaxation time scale of the OU process. In particular, some of the values we observed are significantly below the universal value predicted for immobile obstacles in two dimensions. Therefore, our results show that subdiffusion due to mobile obstacles with OU type of motion may account for the large variation range exhibited by experimental measurements in living cells and may explain that some experimental estimates are below the universal value predicted for immobile obstacles.
Marin, D.; Ribeiro, M. A.; Ribeiro, H. V.; Lenzi, E. K.
2018-07-01
We investigate the solutions for a set of coupled nonlinear Fokker-Planck equations coupled by the diffusion coefficient in presence of external forces. The coupling by the diffusion coefficient implies that the diffusion of each species is influenced by the other and vice versa due to this term, which represents an interaction among them. The solutions for the stationary case are given in terms of the Tsallis distributions, when arbitrary external forces are considered. We also use the Tsallis distributions to obtain a time dependent solution for a linear external force. The results obtained from this analysis show a rich class of behavior related to anomalous diffusion, which can be characterized by compact or long-tailed distributions.
A gedankenexperiment for anomalous diffusion in a charge-fluctuating dusty plasma
International Nuclear Information System (INIS)
Kopp, Andreas; Shchekinov, Yuri A.
2014-01-01
Brownian motion with Gaussian-distributed step-sizes is the prototype of diffusive processes with the typical scaling of the mean-square displacement linear with time. There are, however, processes scaling slower or faster in time due to differently (e.g., power-law) distributed step-sizes, commonly referred to as sub- and superdiffusion, respectively. We address the question whether there is actually a physical reason for a discrimination between normal and anomalous diffusion or whether such processes can be regarded as a special case of normal diffusion with a complicated space- and time-dependent diffusion coefficient. In order to get to the bottom of this question, we construct a numerical gedankenexperiment, which is designed to be as simple as possible and consists of dust particles embedded as test particles into a homogeneous magnetic field that randomly changes their charge. The only parameter governing the system is the ratio of the time-scales for gyration and for recharging. By performing full-orbit simulations of such particles, we are for the first time able to (i) describe a system exhibiting sub-, normal, or superdiffusion as an asymptotic behavior, i.e., not merely as an intermediate state during the evolution of the system. We (ii) observe superdiffusion for low values of the controlling parameter, normal diffusion over a wide plateau of intermediate values, and subdiffusion for high values, i.e., we found (iii) a simple system with one single and illustrative parameter controlling whether the system exhibits super-, normal, or subdiffusion. The crucial point is (iv) a competition between ballistic (particles uncharged, extreme superdiffusion) and confined (charged, extreme subdiffusion) motions. Our system is homogeneous in space and time, so that its (v) behavior cannot be described by normal diffusion with a special diffusion coefficient, and the competition is (vi) fundamentally different from a Gaussian random walk and may be regarded as one
Gao, Qing; Srinivasan, Girish; Magin, Richard L; Zhou, Xiaohong Joe
2011-05-01
To theoretically develop and experimentally validate a formulism based on a fractional order calculus (FC) diffusion model to characterize anomalous diffusion in brain tissues measured with a twice-refocused spin-echo (TRSE) pulse sequence. The FC diffusion model is the fractional order generalization of the Bloch-Torrey equation. Using this model, an analytical expression was derived to describe the diffusion-induced signal attenuation in a TRSE pulse sequence. To experimentally validate this expression, a set of diffusion-weighted (DW) images was acquired at 3 Tesla from healthy human brains using a TRSE sequence with twelve b-values ranging from 0 to 2600 s/mm(2). For comparison, DW images were also acquired using a Stejskal-Tanner diffusion gradient in a single-shot spin-echo echo planar sequence. For both datasets, a Levenberg-Marquardt fitting algorithm was used to extract three parameters: diffusion coefficient D, fractional order derivative in space β, and a spatial parameter μ (in units of μm). Using adjusted R-squared values and standard deviations, D, β, and μ values and the goodness-of-fit in three specific regions of interest (ROIs) in white matter, gray matter, and cerebrospinal fluid, respectively, were evaluated for each of the two datasets. In addition, spatially resolved parametric maps were assessed qualitatively. The analytical expression for the TRSE sequence, derived from the FC diffusion model, accurately characterized the diffusion-induced signal loss in brain tissues at high b-values. In the selected ROIs, the goodness-of-fit and standard deviations for the TRSE dataset were comparable with the results obtained from the Stejskal-Tanner dataset, demonstrating the robustness of the FC model across multiple data acquisition strategies. Qualitatively, the D, β, and μ maps from the TRSE dataset exhibited fewer artifacts, reflecting the improved immunity to eddy currents. The diffusion-induced signal attenuation in a TRSE pulse sequence
Electric current induced forward and anomalous backward mass transport
International Nuclear Information System (INIS)
Somaiah, Nalla; Sharma, Deepak; Kumar, Praveen
2016-01-01
Multilayered test samples were fabricated in form of standard Blech structure, where W was used as the interlayer between SiO 2 substrate and Cu film. Electromigration test was performed at 250 °C by passing an electric current with a nominal density of 3.9 × 10 10 A m −2 . In addition to the regular electromigration induced mass transport ensuing from the cathode towards the anode, we also observed anomalous mass transport from the anode to the cathode, depleting Cu from the anode as well. We propose an electromigration-thermomigration coupling based reasoning to explain the observed mass transport. (letter)
Directory of Open Access Journals (Sweden)
Eldad Kepten
Full Text Available Single particle tracking is an essential tool in the study of complex systems and biophysics and it is commonly analyzed by the time-averaged mean square displacement (MSD of the diffusive trajectories. However, past work has shown that MSDs are susceptible to significant errors and biases, preventing the comparison and assessment of experimental studies. Here, we attempt to extract practical guidelines for the estimation of anomalous time averaged MSDs through the simulation of multiple scenarios with fractional Brownian motion as a representative of a large class of fractional ergodic processes. We extract the precision and accuracy of the fitted MSD for various anomalous exponents and measurement errors with respect to measurement length and maximum time lags. Based on the calculated precision maps, we present guidelines to improve accuracy in single particle studies. Importantly, we find that in some experimental conditions, the time averaged MSD should not be used as an estimator.
Modeling anomalous diffusion by a subordinated fractional Lévy-stable process
International Nuclear Information System (INIS)
Teuerle, Marek; Wyłomańska, Agnieszka; Sikora, Grzegorz
2013-01-01
Two phenomena that can be discovered in systems with anomalous diffusion are long-range dependence and trapping events. The first effect concerns events that are arbitrarily distant but still influence each other exceptionally strongly, which is characteristic for anomalous regimes. The second corresponds to the presence of constant values of the underlying process. Motivated by the relatively poor class of models that can cover these two phenomena, we introduce subordinated fractional Lévy-stable motion with tempered stable waiting times. We present in detail its main properties, propose a simulation scheme and give an estimation procedure for its parameters. The last part of the paper is a presentation, via the Monte Carlo approach, of the effectiveness of the estimation of the parameters. (paper)
Probing the type of anomalous diffusion with single-particle tracking.
Ernst, Dominique; Köhler, Jürgen; Weiss, Matthias
2014-05-07
Many reactions in complex fluids, e.g. signaling cascades in the cytoplasm of living cells, are governed by a diffusion-driven encounter of reactants. Yet, diffusion in complex fluids often exhibits an anomalous characteristic ('subdiffusion'). Since different types of subdiffusion have distinct effects on timing and equilibria of chemical reactions, a thorough determination of the reactants' type of random walk is key to a quantitative understanding of reactions in complex fluids. Here we introduce a straightforward and simple approach for determining the type of subdiffusion from single-particle tracking data. Unlike previous approaches, our method also is sensitive to transient subdiffusion phenomena, e.g. obstructed diffusion below the percolation threshold. We validate our strategy with data from experiment and simulation.
Anomalous Transport in Natural Fracture Networks Induced by Tectonic Stress
Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.
2017-12-01
Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the high uncertainty and large heterogeneity associated with fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transportthrough fractured rock remains poorly understood. The link between anomalous (non-Fickian) transport and confining stress has been shown, only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of geologic (tectonic) stress on flow and tracer transport through natural fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM) [2], which can capture the deformation of matrix blocks, reactivation of pre-existing fractures, and propagation of new cracks, upon changes in the stress field. We apply the model to a fracture network extracted from the geological map of an actual rock outcrop to obtain the aperture field at different stress conditions. We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture network, and show that the stress state is a powerful determinant of transport behavior: (1) An anisotropic stress state induces preferential flow paths through shear dilation; (2) An increase in geologic stress increases aperture heterogeneity that induces late-time tailing of particle breakthrough curves. Finally, we develop an effective transport model that captures the anomalous transport through the stressed fracture
Rashid, Rafi; Chee, Stella Min Ling; Raghunath, Michael; Wohland, Thorsten
2015-04-30
Macromolecular crowding (MMC) has been used in various in vitro experimental systems to mimic in vivo physiology. This is because the crowded cytoplasm of cells contains many different types of solutes dissolved in an aqueous medium. MMC in the extracellular microenvironment is involved in maintaining stem cells in their undifferentiated state (niche) as well as in aiding their differentiation after they have travelled to new locations outside the niche. MMC at physiologically relevant fractional volume occupancies (FVOs) significantly enhances the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells during chemically induced adipogenesis. The mechanism by which MMC produces this enhancement is not entirely known. In the context of extracellular collagen deposition, we have recently reported the importance of optimizing the FVO while minimizing the bulk viscosity. Two opposing properties will determine the net rate of a biochemical reaction: the negative effect of bulk viscosity and the positive effect of the excluded volume, the latter being expressed by the FVO. In this study we have looked more closely at the effect of viscosity on reaction rates. We have used fluorimetry to measure the rate of actin polymerization and fluorescence correlation spectroscopy (FCS) to measure diffusion of various probes in solutions containing the crowder Ficoll at physiological concentrations. Similar to its effect on collagen, Ficoll enhanced the actin polymerization rate despite increasing the bulk viscosity. Our FCS measurements reveal a relatively minor component of anomalous diffusion. In addition, our measurements do suggest that microviscosity becomes relevant in a crowded environment. We ruled out bulk viscosity as a cause of the rate enhancement by performing the actin polymerization assay in glycerol. These opposite effects of Ficoll and glycerol led us to conclude that microviscosity becomes relevant at the length scale of the reacting
Rashid, Rafi; Chee, Stella Min Ling; Raghunath, Michael; Wohland, Thorsten
2015-05-01
Macromolecular crowding (MMC) has been used in various in vitro experimental systems to mimic in vivo physiology. This is because the crowded cytoplasm of cells contains many different types of solutes dissolved in an aqueous medium. MMC in the extracellular microenvironment is involved in maintaining stem cells in their undifferentiated state (niche) as well as in aiding their differentiation after they have travelled to new locations outside the niche. MMC at physiologically relevant fractional volume occupancies (FVOs) significantly enhances the adipogenic differentiation of human bone marrow-derived mesenchymal stem cells during chemically induced adipogenesis. The mechanism by which MMC produces this enhancement is not entirely known. In the context of extracellular collagen deposition, we have recently reported the importance of optimizing the FVO while minimizing the bulk viscosity. Two opposing properties will determine the net rate of a biochemical reaction: the negative effect of bulk viscosity and the positive effect of the excluded volume, the latter being expressed by the FVO. In this study we have looked more closely at the effect of viscosity on reaction rates. We have used fluorimetry to measure the rate of actin polymerization and fluorescence correlation spectroscopy (FCS) to measure diffusion of various probes in solutions containing the crowder Ficoll at physiological concentrations. Similar to its effect on collagen, Ficoll enhanced the actin polymerization rate despite increasing the bulk viscosity. Our FCS measurements reveal a relatively minor component of anomalous diffusion. In addition, our measurements do suggest that microviscosity becomes relevant in a crowded environment. We ruled out bulk viscosity as a cause of the rate enhancement by performing the actin polymerization assay in glycerol. These opposite effects of Ficoll and glycerol led us to conclude that microviscosity becomes relevant at the length scale of the reacting
Zhao, Yi; Cao, Xiangyu; Gao, Jun; Liu, Xiao; Li, Sijia
2016-05-16
We demonstrate a simple reconfigurable metasurface with multiple functions. Anisotropic tiles are investigated and manufactured as fundamental elements. Then, the tiles are combined in a certain sequence to construct a metasurface. Each of the tiles can be adjusted independently which is like a jigsaw puzzle and the whole metasurface can achieve diverse functions by different layouts. For demonstration purposes, we realize polarization conversion, anomalous reflection and diffusion by a jigsaw puzzle metasurface with 6 × 6 pieces of anisotropic tile. Simulated and measured results prove that our method offers a simple and effective strategy for metasurface design.
Fractional single-phase-lagging heat conduction model for describing anomalous diffusion
Directory of Open Access Journals (Sweden)
T.N. Mishra
2016-03-01
Full Text Available The fractional single-phase-lagging (FSPL heat conduction model is obtained by combining scalar time fractional conservation equation to the single-phase-lagging (SPL heat conduction model. Based on the FSPL heat conduction model, anomalous diffusion within a finite thin film is investigated. The effect of different parameters on solution has been observed and studied the asymptotic behavior of the FSPL model. The analytical solution is obtained using Laplace transform method. The whole analysis is presented in dimensionless form. Numerical examples of particular interest have been studied and discussed in details.
Czech Academy of Sciences Publication Activity Database
Jeon, J. H.; Javanainen, M.; Martinez-Seara, Hector; Metzler, R.; Vattulainen, I.
2016-01-01
Roč. 6, č. 2 (2016), č. článku 021006. ISSN 2160-3308 Institutional support: RVO:61388963 Keywords : protein crowding * membranes * simulations * diffusion * non-Gaussian anomalous diffusion Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 12.789, year: 2016 http://journals.aps.org/prx/abstract/10.1103/PhysRevX.6.021006
Méndez, Vicenç; Bartumeus, Frederic
2014-01-01
This book presents the fundamental theory for non-standard diffusion problems in movement ecology. Lévy processes and anomalous diffusion have shown to be both powerful and useful tools for qualitatively and quantitatively describing a wide variety of spatial population ecological phenomena and dynamics, such as invasion fronts and search strategies. Adopting a self-contained, textbook-style approach, the authors provide the elements of statistical physics and stochastic processes on which the modeling of movement ecology is based and systematically introduce the physical characterization of ecological processes at the microscopic, mesoscopic and macroscopic levels. The explicit definition of these levels and their interrelations is particularly suitable to coping with the broad spectrum of space and time scales involved in bio-ecological problems. Including numerous exercises (with solutions), this text is aimed at graduate students and newcomers in this field at the interface of theoretical ecology, mat...
Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M.; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H.
2014-01-01
Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp2 carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations. PMID:25331874
Normal and anomalous diffusion in fluctuations of dust concentration nearby emission source
Szczurek, Andrzej; Maciejewska, Monika; Wyłomańska, Agnieszka; Sikora, Grzegorz; Balcerek, Michał; Teuerle, Marek
2018-02-01
Particulate matter (PM) is an important component of air. Nowadays, major attention is payed to fine dust. It has considerable environmental impact, including adverse effect on human health. One of important issues regarding PM is the temporal variation of its concentration. The variation contains information about factors influencing this quantity in time. The work focuses on the character of PM concentration dynamics indoors, in the vicinity of emission source. The objective was to recognize between the homogeneous or heterogeneous dynamics. The goal was achieved by detecting normal and anomalous diffusion in fluctuations of PM concentration. For this purpose we used anomalous diffusion exponent, β which was derived from Mean Square Displacement (MSD) analysis. The information about PM concentration dynamics may be used to design sampling strategy, which serves to attain representative information about PM behavior in time. The data analyzed in this work was collected from single-point PM concentration monitoring in the vicinity of seven emission sources in industrial environment. In majority of cases we observed heterogeneous character of PM concentration dynamics. It confirms the complexity of interactions between the emission sources and indoor environment. This result also votes against simplistic approach to PM concentration measurement indoors, namely their occasional character, short measurement periods and long term averaging.
Trapped-ion anomalous diffusion coefficient on the basis of single mode saturation
International Nuclear Information System (INIS)
Koshi, Yuji; Hatayama, Akiyoshi; Ogasawara, Masatada.
1982-03-01
Expressions of the anomalous diffusion coefficient due to the dissipative trapped ion instability (DTII) are derived for the case with and without the effect of magnetic shear. Derivation is made by taking into account of the single mode saturation of the DTII previously obtained numerically. In the absence of the shear effect, the diffusion coefficient is proportional to #betta#sub(i)a 2 (#betta#sub(i) is the effective collision frequency of the trapped ions and a is the minor radius of a torus) and is much larger than the neoclassical ion heat conductivity. In the presence of the shear effect, the diffusion coefficient is much smaller than the Kadomtsev and Pogutse's value and is the same order of magnitude as the neoclassical ion heat conductivity. Dependences of the diffusion coefficient on the temperature and on the total particle number density are rather complicated due to the additional spectral cut-off, which is introduced to regularize the short wavelength modes in the numerical analysis. (author)
Continuous-time random-walk model for anomalous diffusion in expanding media
Le Vot, F.; Abad, E.; Yuste, S. B.
2017-09-01
Expanding media are typical in many different fields, e.g., in biology and cosmology. In general, a medium expansion (contraction) brings about dramatic changes in the behavior of diffusive transport properties such as the set of positional moments and the Green's function. Here, we focus on the characterization of such effects when the diffusion process is described by the continuous-time random-walk (CTRW) model. As is well known, when the medium is static this model yields anomalous diffusion for a proper choice of the probability density function (pdf) for the jump length and the waiting time, but the behavior may change drastically if a medium expansion is superimposed on the intrinsic random motion of the diffusing particle. For the case where the jump length and the waiting time pdfs are long-tailed, we derive a general bifractional diffusion equation which reduces to a normal diffusion equation in the appropriate limit. We then study some particular cases of interest, including Lévy flights and subdiffusive CTRWs. In the former case, we find an analytical exact solution for the Green's function (propagator). When the expansion is sufficiently fast, the contribution of the diffusive transport becomes irrelevant at long times and the propagator tends to a stationary profile in the comoving reference frame. In contrast, for a contracting medium a competition between the spreading effect of diffusion and the concentrating effect of contraction arises. In the specific case of a subdiffusive CTRW in an exponentially contracting medium, the latter effect prevails for sufficiently long times, and all the particles are eventually localized at a single point in physical space. This "big crunch" effect, totally absent in the case of normal diffusion, stems from inefficient particle spreading due to subdiffusion. We also derive a hierarchy of differential equations for the moments of the transport process described by the subdiffusive CTRW model in an expanding medium
Continuous-time random-walk model for anomalous diffusion in expanding media.
Le Vot, F; Abad, E; Yuste, S B
2017-09-01
Expanding media are typical in many different fields, e.g., in biology and cosmology. In general, a medium expansion (contraction) brings about dramatic changes in the behavior of diffusive transport properties such as the set of positional moments and the Green's function. Here, we focus on the characterization of such effects when the diffusion process is described by the continuous-time random-walk (CTRW) model. As is well known, when the medium is static this model yields anomalous diffusion for a proper choice of the probability density function (pdf) for the jump length and the waiting time, but the behavior may change drastically if a medium expansion is superimposed on the intrinsic random motion of the diffusing particle. For the case where the jump length and the waiting time pdfs are long-tailed, we derive a general bifractional diffusion equation which reduces to a normal diffusion equation in the appropriate limit. We then study some particular cases of interest, including Lévy flights and subdiffusive CTRWs. In the former case, we find an analytical exact solution for the Green's function (propagator). When the expansion is sufficiently fast, the contribution of the diffusive transport becomes irrelevant at long times and the propagator tends to a stationary profile in the comoving reference frame. In contrast, for a contracting medium a competition between the spreading effect of diffusion and the concentrating effect of contraction arises. In the specific case of a subdiffusive CTRW in an exponentially contracting medium, the latter effect prevails for sufficiently long times, and all the particles are eventually localized at a single point in physical space. This "big crunch" effect, totally absent in the case of normal diffusion, stems from inefficient particle spreading due to subdiffusion. We also derive a hierarchy of differential equations for the moments of the transport process described by the subdiffusive CTRW model in an expanding medium
Anomalous electromagnetically induced transparency in photonic-band-gap materials
International Nuclear Information System (INIS)
Singh, Mahi R.
2004-01-01
The phenomenon of electromagnetically induced transparency has been studied when a four-level atom is located in a photonic band gap material. Quantum interference is introduced by driving the two upper levels of the atom with a strong pump laser field. The top level and one of the ground levels are coupled by a weak probe laser field and absorption takes place between these two states. The susceptibility due to the absorption for this transition has been calculated by using the master equation method in linear response theory. Numerical simulations are performed for the real and imaginary parts of the susceptibility for a photonic band gap material whose gap-midgap ratio is 21%. It is found that when resonance frequencies lie within the band, the medium becomes transparent under the action of the strong pump laser field. More interesting results are found when one of the resonance frequencies lies at the band edge and within the band gap. When the resonance frequency lies at the band edge, the medium becomes nontransparent even under a strong pump laser field. On the other hand, when the resonance frequency lies within the band gap, the medium becomes transparent even under a weak pump laser field. In summary, we found that the medium can be transformed from the transparent state to the nontransparent state just by changing the location of the resonance frequency. We call these two effects anomalous electromagnetically induced transparency
Anomalous diffusion of water molecules at grain boundaries in ice Ih.
Moreira, Pedro Augusto Franco Pinheiro; Veiga, Roberto Gomes de Aguiar; Ribeiro, Ingrid de Almeida; Freitas, Rodrigo; Helfferich, Julian; de Koning, Maurice
2018-05-23
Using ab initio and classical molecular dynamics simulations, we study pre-melting phenomena in pristine coincident-site-lattice grain boundaries (GBs) in proton-disordered hexagonal ice Ih at temperatures just below the melting point Tm. Concerning pre-melt-layer thicknesses, the results are consistent with the available experimental estimates for low-disorder impurity-free GBs. With regard to molecular mobility, the simulations provide a key new insight: the translational motion of the water molecules is found to be subdiffusive for time scales from ∼10 ns up to at least 0.1 μs. Moreover, the fact that the anomalous diffusion occurs even at temperatures just below Tm where the bulk supercooled liquid still diffuses normally suggests that it is related to the confinement of the GB pre-melt layers by the surrounding crystalline environment. Furthermore, we show that this behavior can be characterized by continuous-time random walk models in which the waiting-time distributions decay according to power-laws that are very similar to those describing dynamics in glass-forming systems.
Anomalous diffusion and Levy random walk of magnetic field lines in three dimensional turbulence
International Nuclear Information System (INIS)
Zimbardo, G.; Veltri, P.; Basile, G.; Principato, S.
1995-01-01
The transport of magnetic field lines is studied numerically where three dimensional (3-D) magnetic fluctuations, with a power law spectrum, and periodic over the simulation box are superimposed on an average uniform magnetic field. The weak and the strong turbulence regime, δB∼B 0 , are investigated. In the weak turbulence case, magnetic flux tubes are separated from each other by percolating layers in which field lines undergo a chaotic motion. In this regime the field lines may exhibit Levy, rather than Gaussian, random walk, changing from Levy flights to trapped motion. The anomalous diffusion laws left-angle Δx 2 i right-angle ∝s α with α>1 and α<1, are obtained for a number of cases, and the non-Gaussian character of the field line random walk is pointed out by computing the kurtosis. Increasing the fluctuation level, and, therefore stochasticity, normal diffusion (α congruent 1) is recovered and the kurtoses reach their Gaussian value. However, the numerical results show that neither the quasi-linear theory nor the two dimensional percolation theory can be safely extrapolated to the considered 3-D strong turbulence regime. copyright 1995 American Institute of Physics
Zhang, Yong; Green, Christopher T.; Tick, Geoffrey R.
2015-01-01
This study evaluates the role of the Peclet number as affected by molecular diffusion in transient anomalous transport, which is one of the major knowledge gaps in anomalous transport, by combining Monte Carlo simulations and stochastic model analysis. Two alluvial settings containing either short- or long-connected hydrofacies are generated and used as media for flow and transport modeling. Numerical experiments show that 1) the Peclet number affects both the duration of the power-law segment of tracer breakthrough curves (BTCs) and the transition rate from anomalous to Fickian transport by determining the solute residence time for a given low-permeability layer, 2) mechanical dispersion has a limited contribution to the anomalous characteristics of late-time transport as compared to molecular diffusion due to an almost negligible velocity in floodplain deposits, and 3) the initial source dimensions only enhance the power-law tail of the BTCs at short travel distances. A tempered stable stochastic (TSS) model is then applied to analyze the modeled transport. Applications show that the time-nonlocal parameters in the TSS model relate to the Peclet number, Pe. In particular, the truncation parameter in the TSS model increases nonlinearly with a decrease in Pe due to the decrease of the mean residence time, and the capacity coefficient increases with an increase in molecular diffusion which is probably due to the increase in the number of immobile particles. The above numerical experiments and stochastic analysis therefore reveal that the Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer–aquitard complexes.
Anomalous diffusion and q-Weibull velocity distributions in epithelial cell migration.
Directory of Open Access Journals (Sweden)
Tatiane Souza Vilela Podestá
Full Text Available In multicellular organisms, cell motility is central in all morphogenetic processes, tissue maintenance, wound healing and immune surveillance. Hence, the control of cell motion is a major demand in the creation of artificial tissues and organs. Here, cell migration assays on plastic 2D surfaces involving normal (MDCK and tumoral (B16F10 epithelial cell lines were performed varying the initial density of plated cells. Through time-lapse microscopy quantities such as speed distributions, velocity autocorrelations and spatial correlations, as well as the scaling of mean-squared displacements were determined. We find that these cells exhibit anomalous diffusion with q-Weibull speed distributions that evolves non-monotonically to a Maxwellian distribution as the initial density of plated cells increases. Although short-ranged spatial velocity correlations mark the formation of small cell clusters, the emergence of collective motion was not observed. Finally, simulational results from a correlated random walk and the Vicsek model of collective dynamics evidence that fluctuations in cell velocity orientations are sufficient to produce q-Weibull speed distributions seen in our migration assays.
Seki, Kazuhiko; Bagchi, Kaushik; Bagchi, Biman
2016-05-01
Diffusion in one dimensional rugged energy landscape (REL) is predicted to be pathologically different (from any higher dimension) with a much larger chance of encountering broken ergodicity [D. L. Stein and C. M. Newman, AIP Conf. Proc. 1479, 620 (2012)]. However, no quantitative study of this difference has been reported, despite the prevalence of multidimensional physical models in the literature (like a high dimensional funnel guiding protein folding/unfolding). Paradoxically, some theoretical studies of these phenomena still employ a one dimensional diffusion description for analytical tractability. We explore the dimensionality dependent diffusion on REL by carrying out an effective medium approximation based analytical calculations and compare them with the available computer simulation results. We find that at an intermediate level of ruggedness (assumed to have a Gaussian distribution), where diffusion is well-defined, the value of the effective diffusion coefficient depends on dimensionality and changes (increases) by several factors (˜5-10) in going from 1d to 2d. In contrast, the changes in subsequent transitions (like 2d to 3d and 3d to 4d and so on) are far more modest, of the order of 10-20% only. When ruggedness is given by random traps with an exponential distribution of barrier heights, the mean square displacement (MSD) is sub-diffusive (a well-known result), but the growth of MSD is described by different exponents in one and higher dimensions. The reason for such strong ruggedness induced retardation in the case of one dimensional REL is discussed. We also discuss the special limiting case of infinite dimension (d = ∞) where the effective medium approximation becomes exact and where theoretical results become simple. We discuss, for the first time, the role of spatial correlation in the landscape on diffusion of a random walker.
García-Hernández, Rubén; Melián, Gladys; D'Auria, Luca; Asensio-Ramos, María; Alonso, Mar; Padilla, Germán D.; Rodríguez, Fátima; Padrón, Eleazar; Barrancos, José; García-Merino, Marta; Amonte, Cecilia; Pérez, Aarón; Calvo, David; Hernández, Pedro A.; Pérez, Nemesio M.
2017-04-01
probably due to the increase of fluid pressure in the hydrothermal-magmatic system of Tenerife. With the aim of investigate the relationship of the observed temporal variation on diffuse CO2 emission and the seismic event occurred beneath Teide volcano in January 6, 2016, the anomalous peak of diffuse CO2 emission was tested following the Material Failure Forecast Method (FFM). To do so, a Geochemical Window Precursory Signal (GWPS) was selected between October 11 and December 13, 2016. Plotting the inverse of diffuse CO2 emission rate versus time, the interception of the linear fit of the data with the time axis indicates the theoretical moment when seismicity is most likely to occur. Surprisingly, interception of the linear fit occurred for a time window between January 6 and 9, 2017, showing an excellent correlation with the occurrence of the M 2.5 earthquake registered at Teide in January 6, 2017.
Yuste, S Bravo; Borrego, R; Abad, E
2010-02-01
We consider various anomalous d -dimensional diffusion problems in the presence of an absorbing boundary with radial symmetry. The motion of particles is described by a fractional diffusion equation. Their mean-square displacement is given by r(2) proportional, variant t(gamma)(0divergent series appear when the concentration or survival probabilities are evaluated via the method of separation of variables. While the solution for normal diffusion problems is, at most, divergent as t-->0 , the emergence of such series in the long-time domain is a specific feature of subdiffusion problems. We present a method to regularize such series, and, in some cases, validate the procedure by using alternative techniques (Laplace transform method and numerical simulations). In the normal diffusion case, we find that the signature of the initial condition on the approach to the steady state rapidly fades away and the solution approaches a single (the main) decay mode in the long-time regime. In remarkable contrast, long-time memory of the initial condition is present in the subdiffusive case as the spatial part Psi1(r) describing the long-time decay of the solution to the steady state is determined by a weighted superposition of all spatial modes characteristic of the normal diffusion problem, the weight being dependent on the initial condition. Interestingly, Psi1(r) turns out to be independent of the anomalous diffusion exponent gamma .
Directory of Open Access Journals (Sweden)
Lund Frederik W
2012-10-01
Full Text Available Abstract Background Cholesterol is an important membrane component, but our knowledge about its transport in cells is sparse. Previous imaging studies using dehydroergosterol (DHE, an intrinsically fluorescent sterol from yeast, have established that vesicular and non-vesicular transport modes contribute to sterol trafficking from the plasma membrane. Significant photobleaching, however, limits the possibilities for in-depth analysis of sterol dynamics using DHE. Co-trafficking studies with DHE and the recently introduced fluorescent cholesterol analog BODIPY-cholesterol (BChol suggested that the latter probe has utility for prolonged live-cell imaging of sterol transport. Results We found that BChol is very photostable under two-photon (2P-excitation allowing the acquisition of several hundred frames without significant photobleaching. Therefore, long-term tracking and diffusion measurements are possible. Two-photon temporal image correlation spectroscopy (2P-TICS provided evidence for spatially heterogeneous diffusion constants of BChol varying over two orders of magnitude from the cell interior towards the plasma membrane, where D ~ 1.3 μm2/s. Number and brightness (N&B analysis together with stochastic simulations suggest that transient partitioning of BChol into convoluted membranes slows local sterol diffusion. We observed sterol endocytosis as well as fusion and fission of sterol-containing endocytic vesicles. The mobility of endocytic vesicles, as studied by particle tracking, is well described by a model for anomalous subdiffusion on short time scales with an anomalous exponent α ~ 0.63 and an anomalous diffusion constant of Dα = 1.95 x 10-3 μm2/sα. On a longer time scale (t > ~5 s, a transition to superdiffusion consistent with slow directed transport with an average velocity of v ~ 6 x 10-3 μm/s was observed. We present an analytical model that bridges the two regimes and fit this model to vesicle
International Nuclear Information System (INIS)
Ribeiro, Haroldo V; Alves, Luiz G A; Zola, Rafael S; Lenzi, Ervin K; Tateishi, Angel A
2014-01-01
The comb model is a simplified description for anomalous diffusion under geometric constraints. It represents particles spreading out in a two-dimensional space where the motions in the x-direction are allowed only when the y coordinate of the particle is zero. Here, we propose an extension for the comb model via Langevin-like equations driven by fractional Gaussian noises (long-range correlated). By carrying out computer simulations, we show that the correlations in the y-direction affect the diffusive behavior in the x-direction in a non-trivial fashion, resulting in a quite rich diffusive scenario characterized by usual, superdiffusive or subdiffusive scaling of second moment in the x-direction. We further show that the long-range correlations affect the probability distribution of the particle positions in the x-direction, making their tails longer when noise in the y-direction is persistent and shorter for anti-persistent noise. Our model thus combines and allows the study/analysis of the interplay between different mechanisms of anomalous diffusion (geometric constraints and long-range correlations) and may find direct applications for describing diffusion in complex systems such as living cells. (paper)
Antibiotic-Induced Anomalous Statistics of Collective Bacterial Swarming
Benisty, Sivan; Ben-Jacob, Eshel; Ariel, Gil; Be'er, Avraham
2015-01-01
Under sublethal antibiotics concentrations, the statistics of collectively swarming Bacillus subtilis transitions from normal to anomalous, with a heavy-tailed speed distribution and a two-step temporal correlation of velocities. The transition is due to changes in the properties of the bacterial motion and the formation of a motility-defective subpopulation that self-segregates into regions. As a result, both the colonial expansion and the growth rate are not affected by antibiotics. This phenomenon suggests a new strategy bacteria employ to fight antibiotic stress.
Strain induced anomalous red shift in mesoscopic iron oxide ...
Indian Academy of Sciences (India)
Wintec
pared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the ..... Shape control can also induce anisotropy and thus modify the coercivity of these ... ppines: Addison-Wesley Publishing Company).
Diffusion induced by cyclotron resonance heating
International Nuclear Information System (INIS)
Riyopoulos, S.; Tajima, T.; Hatori, T.; Pfirsch, D.
1985-09-01
The wave induced particle transport during the ion cyclotron resonance heating is studied in collisionless toroidal plasmas. It is shown that the previously neglected non-conservation of the toroidal angular momentum IP/sub phi/ caused by the toroidal wave component E/sub phi/ is necessary to allow particle diffusion and yields the leading diffusive contribution. While the induced ion transport for the rf power in contemporary experiments is of the order of the neoclassical value, that of fast alpha particles is quite large if resonance is present
Strain induced anomalous red shift in mesoscopic iron oxide
Indian Academy of Sciences (India)
Nano magnetic oxides; red shift; magnetic storage. ... size and strain induced modifications of various physical properties viz. optical, magnetic and structural. ... ∼2, are synthesized by employing starch and ethylene glycol and starch and ...
Model for Anomalous Moisture Diffusion through a Polymer-Clay Nanocomposite
DEFF Research Database (Denmark)
Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.
2003-01-01
Experimental data are reported on moisture diffusion and the elastoplastic response of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests showed that water transport in the neat resin is Fickian, whereas...... platelets. Constitutive equations are developed for moisture diffusion through and the elastoplastic behavior of a nanocomposite. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical...
A model for anomalous moisture diffusion through a polymer-clay nanocomposite
DEFF Research Database (Denmark)
Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.
2002-01-01
Experimental data are reported on moisture diffusion and the elastoplastic response in uniaxial tensile tests of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests show that the moisture transport...... diffusion through a nanocomposite and for its elastoplastic behavior. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical simulation....
Anomalous diffusion in a lattice-gas wind-tree model
International Nuclear Information System (INIS)
Kong, X.P.; Cohen, E.G.D.
1989-01-01
Two new strictly deterministic lattice-gas automata derived from Ehrenfest's wind-tree model are studied. While in one model normal diffusion occurs, the other model exhibits abnormal diffusion in that the distribution function of the displacements of the wind particle is non-Gaussian, but its second moment, the mean-square displacement, is proportional to the time, so that a diffusion coefficient can be defined. A connection with the percolation problem and a self-avoiding random walk for the case in which the lattice is completely covered with trees is discussed
Liu, Lin; Zheng, Liancun; Liu, Fawang; Zhang, Xinxin
2016-09-01
An improved Cattaneo-Christov flux model is proposed which can be used to capture the effects of the time and spatial relaxations, the time and spatial inhomogeneous diffusion and the spatial transition probability of cell transport in a highly non-homogeneous medium. Solutions are obtained by numerical discretization method where the time and spatial fractional derivative are discretized by the L1-approximation and shifted Grünwald definition, respectively. The solvability, stability and convergence of the numerical method for the special case of the Cattaneo-Christov equation are proved. Results indicate that the fractional convection diffusion-wave equation is an evolution equation which displays the coexisting characteristics of parabolicity and hyperbolicity. In other words, for α in (0, 1), the cells transport occupies the characteristics of coupling convection diffusion and wave spreading. Moreover, the effects of pertinent time parameter, time and spatial fractional derivative parameters, relaxation parameter, weight coefficient and the convection velocity on the anomalous transport of cells are shown graphically and analyzed in detail.
Mean-squared displacements for normal and anomalous diffusion of grains
International Nuclear Information System (INIS)
Trigger, S A; Heijst, G J F van; Schram, P P J M
2005-01-01
The problem of normal and anomalous space difiusion is formulated on the basis of the integral equations with various type of the probability transition functions for difiusion (PTD functions). For the cases of stationary and time-independent PTD functions the method of fractional differentiation is avoided to construct the correct probability distributions for arbitrary distances, what is important for applications to different stochastic problems. A new general integral equation for the particle distribution, which contains the time-dependent PTD function with one or, for more complicated physical situations, with two times, is formulated and discussed. On this basis fractional differentiation in time is also avoided and a wide class of time dependent PTD functions can be investigated. Calculations of the mean-squared displacements for the various cases are performed on the basis of formulated approach. The particular problems for the PTD functions, dependable from one and for two times, are solved
Anomalous diffusion in body-centred and face-centred cubic metals
International Nuclear Information System (INIS)
Zanghi, J.-P.
1975-10-01
The initial rates of contraction due to self-irradiation damage at 4.2K in three PuSc alloys (5, 12, 18 at % Sc) stabilized in f.c.c. delta-phase were measured. The high negative value of the formation volume of a Frenkel pair which is deduced by extrapolating for pure Pu, can only be explained by assuming that the interstitial Pu may partly recover its distortion energy by creating bonds with its neighbours, by a localized enhancement of the d.f. hybridization and especially by provoking the formation of bonds between its very neighbours. It is shown that about twenty atoms around the interstitial Pu are affected by these bonds. The self-irradiation at 4.2K of a b.c.c. UPuMo alloy was also studied. The activation volume for self-diffusion of Pu in b.c.c. PuZr alloys (10 and 40 at % Zr) was determined. So the validity of Nachtrieb's melting-diffusion correlation could be checked. Indeed, in the Pu 40 at % Zr alloy, which has a pressure temperature diagram the liquidus of which has a positive slope, a positive activation volume was found, whereas in pure epsilon Pu which as a negative slope, the activation volume is negative. A self-diffusion mechanism in PuZr alloys is proposed. A study of the diffusion of Am in these alloys showed that Am and Pu likely diffuse by the same mechanism [fr
Czech Academy of Sciences Publication Activity Database
Kopecký, Miloš; Fábry, Jan; Kub, Jiří
2016-01-01
Roč. 49, Jun (2016), 1016-1020 ISSN 1600-5767 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : X-ray diffuse scattering * atomic displacements * anomalous X-ray scattering * SrTiO 3 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.495, year: 2016
Normal and anomalous diffusion of non-interacting particles in linear nanopores
Zschiegner, S.; Russ, S.; Valiullin, R.; Coppens, M.O.; Dammers, A.J.; Bunde, A.; Kärger, J.
2008-01-01
The diffusion of gas molecules in pores is determined by the collisions between the molecules as well as by the collisions of the molecules with the pore walls. In many applications the so-called Knudsen regime is of particular interest. In this regime the collisions of the molecules with the pore
International Nuclear Information System (INIS)
Zimbardo, G.
2005-01-01
Plasma transport in the presence of turbulence depends on a variety of parameters like the fluctuation level ? B/B0, the ratio between the particle Larmor radius and the turbulence correlation lengths, and the turbulence anisotropy. In this presentation, we review the results of numerical simulations of plasma and magnetic field line transport in the case of anisotropic magnetic turbulence, for parameter values close to those of the solar wind. We assume a uniform background magnetic field B0 = B0ez and a Fourier representation for magnetic fluctuations, with wavectors forming any angle with respect to B0. The energy density spectrum is a power law, and in k space the constant amplitude surfaces are ellipsoids, described by the correlation lengths lx, ly, lz, which quantify the anisotropy of turbulence. For magnetic field lines, we find that transport perpendicular to the background field depends on the Kubo number R = ? B B0 lz lx . For small Kubo numbers, R ? 1, we find anomalous, non Gaussian transport regimes (both sub and superdiffusive) which can be described as a Levy random walk. Increasing the Kubo number, i.e., the fluctuation level ? B/B0 and/or the ratio lz/lx, we find first a quasilinear and then a percolative regime, both corresponding to Gaussian diffusion. For particles, we find that transport parallel and perpendicular to the background magnetic field heavily depends on the turbulence anisotropy and on the particle Larmor radius. For turbulence levels typical of the solar wind, ? B/B0 ? 0.5 ?1, when the ratio between the particle Larmor radius and the turbulence correlation lengths is small, anomalous regimes are found in the case lz/lx ? 1, with Levy random walk (superdiffusion) along the magnetic field and subdiffusion in the perpendicular directions. Conversely, for lz/lx > 1 normal, Gaussian diffusion is found. Increasing the ratio between the particle Larmor radius and the turbulence correlation lengths, the parallel superdiffusion is
Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So
2016-05-01
Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of
Energy Technology Data Exchange (ETDEWEB)
Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So, E-mail: sohirata@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)
2016-05-28
Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D{sub 2}O ice greater than that of H{sub 2}O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born–Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid
International Nuclear Information System (INIS)
Zimbardo, Gaetano
2005-01-01
Plasma transport in the presence of turbulence depends on a variety of parameters such as the fluctuation level, δB/B 0 , the ratio between the particle Larmor radius and the turbulence correlation length, and the turbulence anisotropy. In this paper, we present the results of numerical simulations of plasma and magnetic field line transport in the case of anisotropic magnetic turbulence, for parameter values close to those of the solar wind. We assume a uniform background magnetic field B 0 = B 0 e z and a Fourier representation for magnetic fluctuations, which includes wavectors oblique with respect to B 0 . The energy density spectrum is a power law, and in k space it is described by the correlation lengths l x , l y , l z , which quantify the anisotropy of turbulence. For magnetic field lines, transport perpendicular to the background field depends on the Kubo number R (δB/B 0 ) (l z /l x ). For small Kubo numbers, R 0 , or the ratio l z /l x , we find first a quasilinear regime and then a percolative regime, both corresponding to Gaussian diffusion. For particles, we find that transport parallel and perpendicular to the background magnetic field depends heavily on the turbulence anisotropy and on the particle Larmor radius. For turbulence levels typical of the solar wind, δB/B 0 ≅ 0.5-1, when the ratio between the particle Larmor radius and the turbulence correlation lengths is small, anomalous regimes are found in the case l z /l x ≤ 1, with a Levy random walk (superdiffusion) along the magnetic field and subdiffusion in the perpendicular directions. Conversely, for l z /l x > 1 normal Gaussian diffusion is found. A possible expression for generalized double diffusion is discussed
Electrodeposition of CoNiMo thin films using glycine as additive: anomalous and induced codeposition
International Nuclear Information System (INIS)
Esteves, Marcos C.; Sumodjo, Paulo T.A.; Podlaha, Elizabeth J.
2011-01-01
Highlights: → Mixed/induced codeposition of CoNiMo from a glycine containing bath. → Deposition in a rotating cylinder Hull cell. → The mechanism is explained in term of the complex species that can be formed. - Abstract: The present study focuses on the behavior of the CoNiMo mixed anomalous/induced codeposition process, using glycine as a probe to influence the coverage of adsorbed intermediates. In order to facilitate the investigation of a wide variation of parameters the electrodeposition of the alloy films was performed using a rotating cylinder Hull cell. Alloy composition, current efficiency and partial currents of each metal were analyzed. The partial current densities and hence alloy composition was affected by the amount of glycine in the electrolyte: increasing glycine enhanced both cobalt and molybdenum deposition rates and hindered nickel deposition. It is suggested that the glycine facilitates the adsorption of M(I) adsorbed intermediates that control the anomalous and induced codeposition behavior. The current efficiency ranged from 30 up to 75% and was only slightly affected by glycine at high applied current densities. Films with a tridimensional porous structure were obtained applying current densities higher than 200 mA cm -2 , formed as a consequence of the large hydrogen evolution side reaction, presenting conditions for a novel Mo-alloy electrode structure.
Dynamic correlation of photo-excited electrons: Anomalous levels induced by light–matter coupling
Energy Technology Data Exchange (ETDEWEB)
Jiang, Xiankai [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Huai, Ping, E-mail: huaiping@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Song, Bo, E-mail: bosong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)
2014-04-01
Nonlinear light–matter coupling plays an important role in many aspects of modern physics, such as spectroscopy, photo-induced phase transition, light-based devices, light-harvesting systems, light-directed reactions and bio-detection. However, excited states of electrons are still unclear for nano-structures and molecules in a light field. Our studies unexpectedly present that light can induce anomalous levels in the electronic structure of a donor–acceptor nanostructure with the help of the photo-excited electrons transferring dynamically between the donor and the acceptor. Furthermore, the physics underlying is revealed to be the photo-induced dynamical spin–flip correlation among electrons. These anomalous levels can significantly enhance the electron current through the nanostructure. These findings are expected to contribute greatly to the understanding of the photo-excited electrons with dynamic correlations, which provides a push to the development and application of techniques based on photosensitive molecules and nanostructures, such as light-triggered molecular devices, spectroscopic analysis, bio-molecule detection, and systems for solar energy conversion.
Universal Earthquake-Occurrence Jumps, Correlations with Time, and Anomalous Diffusion
International Nuclear Information System (INIS)
Corral, Alvaro
2006-01-01
Spatiotemporal properties of seismicity are investigated for a worldwide (WW) catalog and for southern California in the stationary case (SC), showing a nearly universal scaling behavior. Distributions of distances between consecutive earthquakes (jumps) are magnitude independent and show two power-law regimes, separated by jump values about 200 (WW) and 15 km (SC). Distributions of waiting times conditioned to the value of jumps show that both variables are correlated, in general, but turn out to be independent when only short or long jumps are considered. Finally, diffusion profiles are found to be independent on the magnitude, contrary to what the waiting-time distributions suggest
Anomalous diffusion, clustering, and pinch of impurities in plasma edge turbulence
DEFF Research Database (Denmark)
Priego, M.; Garcia, O.E.; Naulin, V.
2005-01-01
The turbulent transport of impurity particles in plasma edge turbulence is investigated. The impurities are modeled as a passive fluid advected by the electric and polarization drifts, while the ambient plasma turbulence is modeled using the two-dimensional Hasegawa-Wakatani paradigm for resistive...... drift-wave turbulence. The features of the turbulent transport of impurities are investigated by numerical simulations using a novel code that applies semi-Lagrangian pseudospectral schemes. The diffusive character of the turbulent transport of ideal impurities is demonstrated by relative...... orientation determined by the charge of the impurity particles. Second, a radial pinch scaling linearly with the mass-charge ratio of the impurities is discovered. Theoretical explanation for these observations is obtained by analysis of the model equations. (C) 2005 American Institute of Physics....
Trapping, percolation, and anomalous diffusion of particles in a two-dimensional random field
International Nuclear Information System (INIS)
Avellaneda, M.; Apelian, C.; Elliott, F. Jr.
1993-01-01
The authors analyze the advection of particles in a velocity field with Hamiltonian H(x,y) = bar V 1 y-bar V 2 x + W 1 (y) - W 2 (x), where W i , i=1,2, are random functions with stationary, independent increments. In the absence of molecular diffusion, the particle dynamics are sensitive to the streamline topology, which depends on the mean-to-fluctuations ratio p=max(|bar V 1 |/bar U;|bar V 2 |/bar U), with bar U = [|W' 1 | 2 ] 1/2 = rms fluctuations. The model is exactly solvable for p≥1 and well suited for Monte Carlo simulations for all p. Statistics are considered of streamlines for p=0, deriving power laws for the escape probability and the length of escaping trajectories for a box of size L much-gt 1. Also obtained is a characterization of the statistical topography of the Hamiltonian. The large-scale transport is studied of advected particles with p > 0. For 0 -v/2 [x(t) - (x(t))] and t -v/2 [y(t) - (y(t))]. The large-scale motions are Fickian (v=1) or superdiffusive (v=3/2) with a non-Gaussian coarse-grained probability, according to the direction of the mean velocity relative to the underlying lattice. These results are obtained analytically for p≥1 and extended to the regime 0 1 , bar V 2 ) for which stagnation regions in the flow exist. The results are compared with existing predictions on the topology of streamlines based on percolation theory and with mean-field calculations of effective diffusivities. 29 refs., 15 figs., 7 tabs
Michas, Georgios; Vallianatos, Filippos; Karakostas, Vassilios; Papadimitriou, Eleftheria; Sammonds, Peter
2014-05-01
result that is in accordance to earthquake triggering in global scale (Huc and Main, 2003) and aftershocks diffusion in California (Helmstetter et al., 2003). While other mechanisms may be plausible, the results indicate that anomalous stress transfer due to the occurrence of the two major events control the migration of the aftershock activity, activating different fault segments and having strong implications for the seismic hazard of the area. Acknowledgments. G. Michas wishes to acknowledge the partial financial support from the Greek State Scholarships Foundation (IKY). This work has been accomplished in the framework of the postgraduate program and co-funded through the action "Program for scholarships provision I.K.Y. through the procedure of personal evaluation for the 2011-2012 academic year" from resources of the educational program "Education and Life Learning" of the European Social Register and NSRF 2007- 2013. References Ganas, A., Chousianitis, K., Batsi, E., Kolligri, M., Agalos, A., Chouliaras, G., Makropoulos, K. (2013). The January 2010 Efpalion earthquakes (Gulf of Corinth, central Greece): Earthquake interactions and blind normal faulting. J. of Seism., 17(2), 465-484. Helmstetter, A., Ouillon, G., Sornette, D. (2003). Are aftershocks of large California earthquakes diffusing? J. of Geophys. Res. B, 108(10), 2483. Huc, M., Main, I. G. (2003). Anomalous stress diffusion in earthquake triggering: Correlation length, time dependence, and directionality. J. of Geophys. Res. B, 108(7), 2324. Karakostas, V., Karagianni, E., Paradisopoulou, P. (2012). Space-time analysis, faulting and triggering of the 2010 earthquake doublet in western Corinth gulf. Nat.Haz., 63(2), 1181-1202. Metzler, R., Klafter, J. (2000). The random walk's guide to anomalous diffusion: a fractional dynamics approach. Physics Reports, 339, 1-77. Michas, G., Vallianatos, F., Sammonds, P. (2013). Non-extensivity and long-range correlations in the earthquake activity at the West Corinth
From localization to anomalous diffusion in the dynamics of coupled kicked rotors
Notarnicola, Simone; Iemini, Fernando; Rossini, Davide; Fazio, Rosario; Silva, Alessandro; Russomanno, Angelo
2018-02-01
We study the effect of many-body quantum interference on the dynamics of coupled periodically kicked systems whose classical dynamics is chaotic and shows an unbounded energy increase. We specifically focus on an N -coupled kicked rotors model: We find that the interplay of quantumness and interactions dramatically modifies the system dynamics, inducing a transition between energy saturation and unbounded energy increase. We discuss this phenomenon both numerically and analytically through a mapping onto an N -dimensional Anderson model. The thermodynamic limit N →∞ , in particular, always shows unbounded energy growth. This dynamical delocalization is genuinely quantum and very different from the classical one: Using a mean-field approximation, we see that the system self-organizes so that the energy per site increases in time as a power law with exponent smaller than 1. This wealth of phenomena is a genuine effect of quantum interference: The classical system for N ≥2 always behaves ergodically with an energy per site linearly increasing in time. Our results show that quantum mechanics can deeply alter the regularity or ergodicity properties of a many-body-driven system.
From localization to anomalous diffusion in the dynamics of coupled kicked rotors.
Notarnicola, Simone; Iemini, Fernando; Rossini, Davide; Fazio, Rosario; Silva, Alessandro; Russomanno, Angelo
2018-02-01
We study the effect of many-body quantum interference on the dynamics of coupled periodically kicked systems whose classical dynamics is chaotic and shows an unbounded energy increase. We specifically focus on an N-coupled kicked rotors model: We find that the interplay of quantumness and interactions dramatically modifies the system dynamics, inducing a transition between energy saturation and unbounded energy increase. We discuss this phenomenon both numerically and analytically through a mapping onto an N-dimensional Anderson model. The thermodynamic limit N→∞, in particular, always shows unbounded energy growth. This dynamical delocalization is genuinely quantum and very different from the classical one: Using a mean-field approximation, we see that the system self-organizes so that the energy per site increases in time as a power law with exponent smaller than 1. This wealth of phenomena is a genuine effect of quantum interference: The classical system for N≥2 always behaves ergodically with an energy per site linearly increasing in time. Our results show that quantum mechanics can deeply alter the regularity or ergodicity properties of a many-body-driven system.
Kuentz, M
2003-01-01
A two-dimensional lattice gas automaton (LGA) is used for simulating concentration-dependent diffusion in a microscopically random heterogeneous structure. The heterogeneous medium is initialized at a low density rho sub 0 and then submitted to a steep concentration gradient by continuous injection of particles at a concentration rho sub 1 >rho sub 0 from a one-dimensional source to model spreading of a density front. Whereas the nonlinear diffusion equation generally used to describe concentration-dependent diffusion processes predicts a scaling law of the type phi = xt sup - sup 1 sup / sup 2 in one dimension, the spreading process is shown to deviate from the expected t sup 1 sup / sup 2 scaling. The time exponent is found to be larger than 1/2, i.e. diffusion of the density front is enhanced with respect to standard Fickian diffusion. It is also established that the anomalous time exponent decreases as time elapses: anomalous spreading is thus not a timescaling process. We demonstrate that occurrence of a...
Radiation induced diffusion as a method to protect surface
International Nuclear Information System (INIS)
Baumvol, I.J.R.
1980-01-01
Radiation induced diffusion forms a coating adeherent and without interface on the surface of metalic substrates. This coating improves the behaviour of metal to corrosion and abrasion. The effect of radiation induced diffusion of tin and calcium on pure iron surface is described and analyzed in this work. (author) [pt
Pillai, Rajesh S.; Brakenhoff, G. J.; Müller, M.
2006-09-01
The third harmonic generation (THG) axial response in the vicinity of an interface formed by two isotropic materials of normal dispersion is typically single peaked, with the maximum intensity at the interface position. Here it is shown experimentally that this THG z response may show anomalous behavior—being double peaked with a dip coinciding with the interface position—when the THG contributions from both materials are of similar magnitude. The observed anomalous behavior is explained, using paraxial Gaussian theory, by considering dispersion induced shape changes in the THG z response.
Surface modifications by field induced diffusion.
Directory of Open Access Journals (Sweden)
Martin Olsen
Full Text Available By applying a voltage pulse to a scanning tunneling microscope tip the surface under the tip will be modified. We have in this paper taken a closer look at the model of electric field induced surface diffusion of adatoms including the van der Waals force as a contribution in formations of a mound on a surface. The dipole moment of an adatom is the sum of the surface induced dipole moment (which is constant and the dipole moment due to electric field polarisation which depends on the strength and polarity of the electric field. The electric field is analytically modelled by a point charge over an infinite conducting flat surface. From this we calculate the force that cause adatoms to migrate. The calculated force is small for voltage used, typical 1 pN, but due to thermal vibration adatoms are hopping on the surface and even a small net force can be significant in the drift of adatoms. In this way we obtain a novel formula for a polarity dependent threshold voltage for mound formation on the surface for positive tip. Knowing the voltage of the pulse we then can calculate the radius of the formed mound. A threshold electric field for mound formation of about 2 V/nm is calculated. In addition, we found that van der Waals force is of importance for shorter distances and its contribution to the radial force on the adatoms has to be considered for distances smaller than 1.5 nm for commonly used voltages.
Anomalous plasma heating induced by modulation of the current-density profile
International Nuclear Information System (INIS)
Lopes Cardozo, N.J.
1985-05-01
The usual plasma heating in a tokamak needs additional heating to reach ignition temperature (approx. 10 8 K). The method used in the TORTUR III experiment is to induce anomalous plasma resistivity by applying a short (10 microseconds) high-voltage pulse. A sharp rise of the plasma temperature is found almost simultaneously, but this effect, though considerable, is too short-lived to be of interest for a thermonuclear chain reaction. A second pulse gives a second rise of temperature, but this time a slow one, extending over several milliseconds. The mechanism of this delayed heating and the reservoir within the plasma supplying the energy are subjects of investigation in the TORTUR III experiments. Some conclusions concerning the plasma heating mechanism are presented. The conclusion is reached that the application of the high-voltage pulse results in a modulation of the current-density profile: the (normally already peaked) profile sharpens, the current concentrates in the centre of the plasma column. This is a non-equilibrium situation. It relaxes to the noraml current distribution within approximately 2 milliseconds. As long as this relaxation process is not finished, the dissipation is on an enhanced level and anomalous plasma heating is observed. Many plasma parameters are surveyed and evaluated: temperature (both of the ions and the electrons), density, emission spectrum (from microwaves to hard X-rays) and the fluctuation spectrum. Main subject of this report is the measurement and interpretation of the X-rays of the emission spectrum. Experimental results are presented and discussed
Energy Technology Data Exchange (ETDEWEB)
Burrowes, Delilah; Deng, Jie [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States); Northwestern University, Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Fangusaro, Jason R. [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Hematology/Oncology, Chicago, IL (United States); Northwestern University, Feinberg School of Medicine, Department of Pediatrics-Hematology, Oncology, and Stem Cell Transplantation, Chicago, IL (United States); Nelson, Paige C.; Rozenfeld, Michael J. [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Medical Imaging, Chicago, IL (United States); Zhang, Bin [Cincinnati Children' s Hospital Medical Center, Department of Biostatistics and Epidemiology, Cincinnati, OH (United States); Wadhwani, Nitin R. [Ann and Robert H. Lurie Children' s Hospital of Chicago, Department of Pathology and Laboratory Medicine, Chicago, IL (United States); Northwestern University, Feinberg School of Medicine, Department of Pathology, Chicago, IL (United States)
2017-08-15
The purpose of this study was to examine advanced diffusion-weighted magnetic resonance imaging (DW-MRI) models for differentiation of low- and high-grade tumors in the diagnosis of pediatric brain neoplasms. Sixty-two pediatric patients with various types and grades of brain tumors were evaluated in a retrospective study. Tumor type and grade were classified using the World Health Organization classification (WHO I-IV) and confirmed by pathological analysis. Patients underwent DW-MRI before treatment. Diffusion-weighted images with 16 b-values (0-3500 s/mm{sup 2}) were acquired. Averaged signal intensity decay within solid tumor regions was fitted using two-compartment and anomalous diffusion models. Intracellular and extracellular diffusion coefficients (D{sub slow} and D{sub fast}), fractional volumes (V{sub slow} and V{sub fast}), generalized diffusion coefficient (D), spatial constant (μ), heterogeneity index (β), and a diffusion index (index{sub d}iff = μ x V{sub slow}/β) were calculated. Multivariate logistic regression models with stepwise model selection algorithm and receiver operating characteristic (ROC) analyses were performed to evaluate the ability of each diffusion parameter to distinguish tumor grade. Among all parameter combinations, D and index{sub d}iff jointly provided the best predictor for tumor grades, where lower D (p = 0.03) and higher index{sub d}iff (p = 0.009) were significantly associated with higher tumor grades. In ROC analyses of differentiating low-grade (I-II) and high-grade (III-IV) tumors, index{sub d}iff provided the highest specificity of 0.97 and D provided the highest sensitivity of 0.96. Multi-parametric diffusion measurements using two-compartment and anomalous diffusion models were found to be significant discriminants of tumor grading in pediatric brain neoplasms. (orig.)
International Nuclear Information System (INIS)
Liu, Siyang; Zhang, Chunwei; Sun, Weifeng; Su, Wei; Wang, Shaorong; Ma, Shulang; Huang, Yu
2014-01-01
Anomalous output characteristic shift of the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer is investigated. It shows that the linear drain current has obvious decrease when the output characteristic of fresh device is measured for two consecutive times. The charge pumping experiments demonstrate that the decrease is not from hot-carrier degradation. The reduction of cross section area for the current flowing, which results from the squeezing of the depletion region surrounding the P-top layer, is responsible for the shift. Consequently, the current capability of this special device should be evaluated by the second measured output characteristic
Energy Technology Data Exchange (ETDEWEB)
Liu, Siyang; Zhang, Chunwei; Sun, Weifeng, E-mail: swffrog@seu.edu.cn [National ASIC System Engineering Research Center, Southeast University, Nanjing 210096 (China); Su, Wei; Wang, Shaorong; Ma, Shulang; Huang, Yu [CSMC Technologies Corporation, Wuxi 214061 (China)
2014-04-14
Anomalous output characteristic shift of the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer is investigated. It shows that the linear drain current has obvious decrease when the output characteristic of fresh device is measured for two consecutive times. The charge pumping experiments demonstrate that the decrease is not from hot-carrier degradation. The reduction of cross section area for the current flowing, which results from the squeezing of the depletion region surrounding the P-top layer, is responsible for the shift. Consequently, the current capability of this special device should be evaluated by the second measured output characteristic.
da Silva, Roberto; Vainstein, Mendeli H.; Gonçalves, Sebastián; Paula, Felipe S. F.
2013-08-01
Statistics of soccer tournament scores based on the double round robin system of several countries are studied. Exploring the dynamics of team scoring during tournament seasons from recent years we find evidences of superdiffusion. A mean-field analysis results in a drift velocity equal to that of real data but in a different diffusion coefficient. Along with the analysis of real data we present the results of simulations of soccer tournaments obtained by an agent-based model which successfully describes the final scoring distribution [da Silva , Comput. Phys. Commun.CPHCBZ0010-465510.1016/j.cpc.2012.10.030 184, 661 (2013)]. Such model yields random walks of scores over time with the same anomalous diffusion as observed in real data.
Diffuse Transcranial Electrical Stimulation (DTES)-induced ...
African Journals Online (AJOL)
Higher voltages were needed to induce convulsion in pretreated animals than in normal animals. It is therefore suggestive that DTES-induced hypermotility can be used as an animal model for testing drugs that can be of advantage in the management of non convulsive (petit mal) status epilepticus (SE), and DTES induced ...
Shin, Hyun Kyung; Choi, Bongsik; Talkner, Peter; Lee, Eok Kyun
2014-12-01
Based on the generalized Langevin equation for the momentum of a Brownian particle a generalized asymptotic Einstein relation is derived. It agrees with the well-known Einstein relation in the case of normal diffusion but continues to hold for sub- and super-diffusive spreading of the Brownian particle's mean square displacement. The generalized asymptotic Einstein relation is used to analyze data obtained from molecular dynamics simulations of a two-dimensional soft disk fluid. We mainly concentrated on medium densities for which we found super-diffusive behavior of a tagged fluid particle. At higher densities a range of normal diffusion can be identified. The motion presumably changes to sub-diffusion for even higher densities.
Diffusion MR findings in cyclosporin-A induced encephalopathy
International Nuclear Information System (INIS)
Aydin, Kubilay; Minareci, Ozenc; Donmez, Fuldem; Tuzun, Umit; Atamer, Tanju
2004-01-01
Cyclosporin encephalopathy is a well-known entity, which is clinically characterized by altered mental status, vision problems, focal neurological deficits and seizures. The exact pathophysiology of the cyclosporin encephalopathy has not yet been defined. We report the diffusion-weighted MR imaging and proton MR spectroscopy findings in a case of cyclosporin encephalopathy. The white-matter lesions with reversible restricted diffusion supported the hypothesis of reversible vasospasm induced by the cyclosporin. (orig.)
Computation of shear-induced collective-diffusivity in emulsions
Malipeddi, Abhilash Reddy; Sarkar, Kausik
2017-11-01
The shear-induced collective-diffusivity of drops in an emulsion is calculated through simulation. A front-tracking finite difference method is used to integrate the Navier-Stokes equations. When a cloud of drops is subjected to shear flow, after a certain time, the width of the cloud increases with the 1/3 power of time. This scaling of drop-cloud-width with time is characteristic of (sub-)diffusion that arises from irreversible two-drop interactions. The collective diffusivity is calculated from this relationship. A feature of the procedure adopted here is the modest computational requirement, wherein, a few drops ( 70) in shear for short time ( 70 strain) is found to be sufficient to get a good estimate. As far as we know, collective-diffusivity has not been calculated for drops through simulation till now. The computed values match with experimental measurements reported in the literature. The diffusivity in emulsions is calculated for a range of Capillary (Ca) and Reynolds (Re) numbers. It is found to be a unimodal function of Ca , similar to self-diffusivity. A sub-linear increase of the diffusivity with Re is seen for Re < 5 . This work has been limited to a viscosity matched case.
Membrane formation : diffusion induced demixing processes in ternary polymeric systems
Reuvers, Albertus Johannes
1987-01-01
In this thesis the mechanism of membrane formation by means of immersion precipitation is studied. Immersion of a concentrated polymer solution film into a nonsolvent bath induces an exchange of solvent and nonsolvent in the film by means of diffusion. This process results in an asymmetric polymer
MO-G-BRF-07: Anomalously Fast Diffusion of Carbon Nanotubes Carriers in 3D Tissue Model
Energy Technology Data Exchange (ETDEWEB)
Wang, Y; Bahng, J; Kotov, N [University of Michigan, Ann Arbor, MI (United States)
2014-06-15
Purpose: We aim to investigate and understand diffusion process of carbon nanotubes (CNTs) and other nanoscale particles in tissue and organs. Methods: In this research, we utilized a 3D model tissue of hepatocellular carcinoma (HCC)cultured in inverted colloidal crystal (ICC) scaffolds to compare the diffusivity of CNTs with small molecules such as Rhodamine and FITC in vitro, and further investigated the transportation of CNTs with and without targeting ligand, TGFβ1. The real-time permeation profiles of CNTs in HCC tissue model with high temporal and spatial resolution was demonstrated by using standard confocal microscopy. Quantitative analysis of the diffusion process in 3D was carried out using luminescence intensity in a series of Z-stack images obtained for different time points of the diffusion process after initial addition of CNTs or small molecules to the cell culture and the image data was analyzed by software ImageJ and Mathematica. Results: CNTs display diffusion rate in model tissues substantially faster than small molecules of the similar charge such as FITC, and the diffusion rate of CNTs are significantly enhanced with targeting ligand, TGFβ1. Conclusion: In terms of the advantages of in-vitro model, we were able to have access to measuring the rate of CNT penetration at designed conditions with variable parameters. And the findings by using this model, changed our understanding about advantages of CNTs as nanoscale drug carriers and provides design principles for making new drug carriers for both treatment and diagnostics. Additionally the fast diffusion opens the discussion of the best possible drug carriers to reach deep parts of cancerous tissues, which is often a prerequisite for successful cancer treatment. This work was supported by the Center for Photonic and Multiscale Nanomaterials funded by National Science Foundation Materials Research Science and Engineering Center program DMR 1120923. The work was also partially supported by NSF
MO-G-BRF-07: Anomalously Fast Diffusion of Carbon Nanotubes Carriers in 3D Tissue Model
International Nuclear Information System (INIS)
Wang, Y; Bahng, J; Kotov, N
2014-01-01
Purpose: We aim to investigate and understand diffusion process of carbon nanotubes (CNTs) and other nanoscale particles in tissue and organs. Methods: In this research, we utilized a 3D model tissue of hepatocellular carcinoma (HCC)cultured in inverted colloidal crystal (ICC) scaffolds to compare the diffusivity of CNTs with small molecules such as Rhodamine and FITC in vitro, and further investigated the transportation of CNTs with and without targeting ligand, TGFβ1. The real-time permeation profiles of CNTs in HCC tissue model with high temporal and spatial resolution was demonstrated by using standard confocal microscopy. Quantitative analysis of the diffusion process in 3D was carried out using luminescence intensity in a series of Z-stack images obtained for different time points of the diffusion process after initial addition of CNTs or small molecules to the cell culture and the image data was analyzed by software ImageJ and Mathematica. Results: CNTs display diffusion rate in model tissues substantially faster than small molecules of the similar charge such as FITC, and the diffusion rate of CNTs are significantly enhanced with targeting ligand, TGFβ1. Conclusion: In terms of the advantages of in-vitro model, we were able to have access to measuring the rate of CNT penetration at designed conditions with variable parameters. And the findings by using this model, changed our understanding about advantages of CNTs as nanoscale drug carriers and provides design principles for making new drug carriers for both treatment and diagnostics. Additionally the fast diffusion opens the discussion of the best possible drug carriers to reach deep parts of cancerous tissues, which is often a prerequisite for successful cancer treatment. This work was supported by the Center for Photonic and Multiscale Nanomaterials funded by National Science Foundation Materials Research Science and Engineering Center program DMR 1120923. The work was also partially supported by NSF
International Nuclear Information System (INIS)
Pigarov, Alexander
2012-01-01
This is the final report for the Research Grant DE-FG02-08ER54989 'Edge Plasma Simulations in NSTX and CTF: Synergy of Lithium Coating, Non-Diffusive Anomalous Transport and Drifts'. The UCSD group including: A.Yu. Pigarov (PI), S.I. Krasheninnikov and R.D. Smirnov, was working on modeling of the impact of lithium coatings on edge plasma parameters in NSTX with the multi-species multi-fluid code UEDGE. The work was conducted in the following main areas: (i) improvements of UEDGE model for plasma-lithium interactions, (ii) understanding the physics of low-recycling divertor regime in NSTX caused by lithium pumping, (iii) study of synergistic effects with lithium coatings and non-diffusive ballooning-like cross-field transport, (iv) simulation of experimental multi-diagnostic data on edge plasma with lithium pumping in NSTX via self-consistent modeling of D-Li-C plasma with UEDGE, and (v) working-gas balance analysis. The accomplishments in these areas are given in the corresponding subsections in Section 2. Publications and presentations made under the Grant are listed in Section 3.
Instability induced by cross-diffusion in reaction-diffusion systems
DEFF Research Database (Denmark)
Tian, Canrong; Lin, Zhigui; Pedersen, Michael
2010-01-01
In this paper the instability of the uniform equilibrium of a general strongly coupled reaction–diffusion is discussed. In unbounded domain and bounded domain the sufficient conditions for the instability are obtained respectively. The conclusion is applied to the ecosystem, it is shown that cros...... can induce the instability of an equilibrium which is stable for the kinetic system and for the self-diffusion–reaction system.......In this paper the instability of the uniform equilibrium of a general strongly coupled reaction–diffusion is discussed. In unbounded domain and bounded domain the sufficient conditions for the instability are obtained respectively. The conclusion is applied to the ecosystem, it is shown that cross-diffusion...
Salazar, J.; Hernandez, P.; Perez, N.; Barahona, F.; Olmos, R.; Cartagena, R.; Soriano, T.; Notsu, K.; Lopez, D.
2001-12-01
San Vicente or Chichontepeque (2,180 m a.s.l.) is a composite andesitic volcano located 50 Km east of San Salvador. Its paired edifice rises from the so-called Central Graben, an extensional structure parallel to the Pacific coast, and has been inactive for the last 3000 yrs. Fumaroles (98.2°C ) and hot spring waters are present along radial faults at two localities on the northern slope of the volcano (Aguas Agrias and El Infiernillo). CO2 is the most abundant component in the dry gas (>90%) and its mean isotopic composition (δ 13C(CO2)=-2.11 ‰ and 3He/4He of 6.9 Ra) suggests a magmatic origin for the CO2. These manifestations are supposed to be linked to a 1,200 m depth 250°C reservoir with a CO2 partial pressure of 14 bar extended beneath the volcano (Aiuppa et al., 1997). In February 13, 2001, a 6.6 magnitude earthquake with epicenter about 20 Km W of San Vicente damaged and destroyed many towns and villages in the north area of the volcano causing some deceases. In addition, two seismic swarms were recorded beneath the northeastern flank of the volcano in April and May 2001. Searching for any link between the actual seismic activity and changes in the diffuse CO2 degassing at San Vicente, an NDIR instrument for continuos monitoring of the diffuse CO2 degassing was set up at Aguas Agrias in March 2001. Soil CO2 efflux and several meteorological and soil physical variables were measured in an hourly basis. Very significative pre-seismic and post-seismic relationships have been found in the observed diffuse CO2 efflux temporal variations related to the May 2001 seismic swarms. A sustained 50% increase on the average diffuse CO2 efflux was observed 8 days before the May 8, 5.1 magnitude earthquake. This pre-seismic behaviour may be considered a precursor of the May 2001 seismic swarm at San Vicente volcano. However, about a three-fold increase in the diffuse CO2 efflux was also observed after the intense seismicity recorded on May 8-9. These preliminary
'Complexity' and anomalous transport in space plasmas
International Nuclear Information System (INIS)
Chang, Tom; Wu Chengchin
2002-01-01
'Complexity' has become a hot topic in nearly every field of modern physics. Space plasma is of no exception. In this paper, it is demonstrated that the sporadic and localized interactions of magnetic coherent structures are the origin of 'complexity' in space plasmas. The intermittent localized interactions, which generate the anomalous diffusion, transport, and evolution of the macroscopic state variables of the overall dynamical system, may be modeled by a triggered (fast) localized chaotic growth equation of a set of relevant order parameters. Such processes would generally pave the way for the global system to evolve into a 'complex' state of long-ranged interactions of fluctuations, displaying the phenomenon of forced and/or self-organized criticality. An example of such type of anomalous transport and evolution in a sheared magnetic field is provided via two-dimensional magnetohydrodynamic simulations. The coarse-grained dissipation due to the intermittent triggered interactions among the magnetic coherent structures induces a 'fluctuation-induced nonlinear instability' that reconfigures the sheared magnetic field into an X-point magnetic geometry (in the mean field sense), leading to the anomalous acceleration of the magnetic coherent structures. A phenomenon akin to such type of anomalous transport and acceleration, the so-called bursty bulk flows, has been commonly observed in the plasma sheet of the Earth's magnetotail
Tunable anomalous hall effect induced by interfacial catalyst in perpendicular multilayers
Zhang, J. Y.; Peng, W. L.; Sun, Q. Y.; Liu, Y. W.; Dong, B. W.; Zheng, X. Q.; Yu, G. H.; Wang, C.; Zhao, Y. C.; Wang, S. G.
2018-04-01
The interfacial structures, playing a critical role on the transport properties and the perpendicular magnetic anisotropy in thin films and multilayers, can be modified by inserting an ultrathin functional layer at the various interfaces. The anomalous Hall effect (AHE) in the multilayers with core structure of Ta/CoFeB/X/MgO/Ta (X: Hf or Pt) is tuned by interfacial catalytic engineering. The saturation anomalous Hall resistance (RAH) is increased by 16.5% with 0.1 nm Hf insertion compared with the reference sample without insertion. However, the RAH value is decreased by 9.0% with 0.1 nm Pt insertion. The interfacial states were characterized by the X-ray photoelectron spectroscopy (XPS). The XPS results indicate that a strong bonding between Hf and O for Hf insertion, but no bonding between Pt and O for Pt insertion. The bonding between metal and oxygen leads to various oxygen migration behavior at the interfaces. Therefore, the opposite behavior about the RAH originates from the different oxygen behavior due to various interfacial insertion. This work provides a new approach to manipulate spin transport property for the potential applications.
Doping of silicon by laser-induced diffusion
International Nuclear Information System (INIS)
Pretorius, R.; Allie, M.S.
1986-01-01
This report gives information on the doping of silicon by laser-induced diffusion, modelling and heat-flow calculation, doping from evaporated layers and silicon self-diffusion during pulsed laser irradiation. In order to tailor dopant profiles accurately a knowledge of the heat flow and the melt depths attained as a function of laser energy and material type is crucial. The heat flow calculations described can be used in conjuntion with most diffusion equations in order to predict the redistribution of the deposited dopant which occurs as a result of liquid phase diffusion during the melting period. Doping of Si was carried out by evaporating this films of Sb, In and Bi 10 to 300 A thick, onto the substrates. During pulsed laser irradiation the dopant film and underlying silicon substrate is melted and the dopant incorporated into the crystal lattice during recrystallization. Radioactive 31 Si(T1/2=2,62h) was used as a tracer to measure the self-diffusion of silicon in silicon during pulsed laser (pulsewidth = 30ns, wavelength = 694nm) irradiation
Pump, sodium, inducer, intermediate size (ISIP) (impeller/inducer/diffuser retrofit)
International Nuclear Information System (INIS)
Paradise, D.R.
1978-01-01
This specification defines the requirements for the Intermediate-Size Inducer Pump (ISIP), which is to be made by replacing the impeller of the FFTF Prototype Pump with a new inducer, impeller, diffuser, seal, and necessary adapter hardware. Subsequent testing requirements of the complete pump assembly are included
Diffusion processes in bombardment-induced surface topography
International Nuclear Information System (INIS)
Robinson, R.S.
1984-01-01
The bombardment of surfaces with moderate energy ions can lead to the development of various micron-sized surface structures. These structures include ridges, ledges, flat planes, pits and cones. The causal phenomena in the production of these features are sputtering, ion reflection, redeposition of sputtered material, and surface diffusion of both impurity and target-atom species. The authors concentrate on the formation of ion bombardment-induced surface topography wherein surface diffusion is a dominant process. The most thoroughly understood aspect of this topography development is the generation of cone-like structures during sputtering. The formation of cones during sputtering has been attributed to three effects. These are: (1) the presence of asperities, defects, or micro-inclusions in the surface layers, (2) the presence of impurities on the surfaces, and (3) particular crystal orientations. (Auth.)
Anomalous Ion Heating, Intrinsic and Induced Rotation in the Pegasus Toroidal Experiment
Burke, M. G.; Barr, J. L.; Bongard, M. W.; Fonck, R. J.; Hinson, E. T.; Perry, J. M.; Redd, A. J.; Thome, K. E.
2014-10-01
Pegasus plasmas are initiated through either standard, MHD stable, inductive current drive or non-solenoidal local helicity injection (LHI) current drive with strong reconnection activity, providing a rich environment to study ion dynamics. During LHI discharges, a large amount of anomalous impurity ion heating has been observed, with Ti ~ 800 eV but Te < 100 eV. The ion heating is hypothesized to be a result of large-scale magnetic reconnection activity, as the amount of heating scales with increasing fluctuation amplitude of the dominant, edge localized, n = 1 MHD mode. Chordal Ti spatial profiles indicate centrally peaked temperatures, suggesting a region of good confinement near the plasma core surrounded by a stochastic region. LHI plasmas are observed to rotate, perhaps due to an inward radial current generated by the stochastization of the plasma edge by the injected current streams. H-mode plasmas are initiated using a combination of high-field side fueling and Ohmic current drive. This regime shows a significant increase in rotation shear compared to L-mode plasmas. In addition, these plasmas have been observed to rotate in the counter-Ip direction without any external momentum sources. The intrinsic rotation direction is consistent with predictions from the saturated Ohmic confinement regime. Work supported by US DOE Grant DE-FG02-96ER54375.
Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers
Guo, Zaibing
2012-09-27
In this paper, we report the results of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers with perpendicular magnetic anisotropy. The surface scattering effect has been extracted from the total anomalous Hall effect. By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced by rapid thermal annealing modifies not only the magnetization and longitudinal resistivity but also the anomalous Hall effect; a large exponent γ ∼ 5.7 has been attributed to interface scattering-dominated anomalous Hall effect.
Irradiation spectrum and ionization-induced diffusion effects in ceramics
Energy Technology Data Exchange (ETDEWEB)
Zinkle, S.J. [Oak Ridge National Lab., TN (United States)
1997-08-01
There are two main components to the irradiation spectrum which need to be considered in radiation effects studies on nonmetals, namely the primary knock-on atom energy spectrum and ionizing radiation. The published low-temperature studies on Al{sub 2}O{sub 3} and MgO suggest that the defect production is nearly independent of the average primary knock-on atom energy, in sharp contrast to the situation for metals. On the other hand, ionizing radiation has been shown to exert a pronounced influence on the microstructural evolution of both semiconductors and insulators under certain conditions. Recent work on the microstructure of ion-irradiated ceramics is summarized, which provides evidence for significant ionization-induced diffusion. Polycrystalline samples of MgO, Al{sub 2}O{sub 3}, and MgAl{sub 2}O{sub 4} were irradiated with various ions ranging from 1 MeV H{sup +} to 4 MeV Zr{sup +} ions at temperatures between 25 and 650{degrees}C. Cross-section transmission electron microscopy was used to investigate the depth-dependent microstructural of the irradiated specimens. Dislocation loop nucleation was effectively suppressed in specimens irradiated with light ions, whereas the growth rate of dislocation loops was enhanced. The sensitivity to irradiation spectrum is attributed to ionization-induced diffusion. The interstitial migration energies in MgAl{sub 2}O{sub 4} and Al{sub 2}O{sub 3} are estimated to be {le}0.4 eV and {le}0.8 eV, respectively for irradiation conditions where ionization-induced diffusion effects are expected to be negligible.
Renewal-anomalous-heterogeneous files
International Nuclear Information System (INIS)
Flomenbom, Ophir
2010-01-01
Renewal-anomalous-heterogeneous files are solved. A simple file is made of Brownian hard spheres that diffuse stochastically in an effective 1D channel. Generally, Brownian files are heterogeneous: the spheres' diffusion coefficients are distributed and the initial spheres' density is non-uniform. In renewal-anomalous files, the distribution of waiting times for individual jumps is not exponential as in Brownian files, yet obeys: ψ α (t)∼t -1-α , 0 2 >, obeys, 2 >∼ 2 > nrml α , where 2 > nrml is the MSD in the corresponding Brownian file. This scaling is an outcome of an exact relation (derived here) connecting probability density functions of Brownian files and renewal-anomalous files. It is also shown that non-renewal-anomalous files are slower than the corresponding renewal ones.
Goretzki, Nora; Inbar, Nimrod; Kühn, Michael; Möller, Peter; Rosenthal, Eliyahu; Schneider, Michael; Siebert, Christian; Magri, Fabien
2016-04-01
The Lower Yarmouk Gorge, at the border between Israel and Jordan, is characterized by an anomalous temperature gradient of 46 °C/km. Numerical simulations of thermally-driven flow show that ascending thermal waters are the result of mixed convection, i.e. the interaction between the regional flow from the surrounding heights and buoyant flow within permeable faults [1]. Those models were calibrated against available temperature logs by running several forward problems (FP), with a classic "trial and error" method. In the present study, inverse problems (IP) are applied to find alternative parameter distributions that also lead to the observed thermal anomalies. The investigated physical parameters are hydraulic conductivity and thermal conductivity. To solve the IP, the PEST® code [2] is applied via the graphical interface FEPEST® in FEFLOW® [3]. The results show that both hydraulic and thermal conductivity are consistent with the values determined with the trial and error calibrations, which precede this study. However, the IP indicates that the hydraulic conductivity of the Senonian Paleocene aquitard can be 8.54*10-3 m/d, which is three times lower than the originally estimated value in [1]. Moreover, the IP suggests that the hydraulic conductivity in the faults can increase locally up to 0.17 m/d. These highly permeable areas can be interpreted as local damage zones at the faults/units intersections. They can act as lateral pathways in the deep aquifers that allow deep outflow of thermal water. This presentation provides an example about the application of FP and IP to infer a wide range of parameter values that reproduce observed environmental issues. [1] Magri F, Inbar N, Siebert C, Rosenthal E, Guttman J, Möller P (2015) Transient simulations of large-scale hydrogeological processes causing temperature and salinity anomalies in the Tiberias Basin. Journal of Hydrology, 520, 342-355 [2] Doherty J (2010) PEST: Model-Independent Parameter Estimation. user
International Nuclear Information System (INIS)
Kubaschewski, O.
1983-01-01
The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes
International Nuclear Information System (INIS)
Schroy, C.B.; Todd, P.
1979-01-01
Cultured Chinese hamster cell line V79-79 exhibited an increase in survival with increasing UV fluence after a sharp decrease when exposed to 2.5 mM caffeine for 44 h after far-UV irradiation resulting in an anomalous maximum in the survival curve. No survival maximum was evident when either 0 or 1 mM caffeine is administered under the same conditions. The UV survival curve for 2.5 mM caffeine crossed the corresponding 1 mM curve and apparently became asymptotic to the 0 mM curve as UV fluence was increased. Chinese hamster cell lines V79-753B (related to V79-79 by derivation from the same parental line) and M3-1F3 (unrelated) exhibited only potentiation of post-UV lethality by the same concentration of caffeine and had no caffeine-induced anomalies in their survival curves. Xanthine, used alone or in combination with caffeine, only potentiated a slight amount of lethality and appeared not to be a major causative factor of the anomaly. (author)
Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers
Guo, Zaibing; Mi, W. B.; Aboljadayel, Razan; Zhang, Bei; Zhang, Q.; Gonzalez Barba, Priscila; Manchon, Aurelien; Zhang, Xixiang
2012-01-01
. By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced
A current induced diffusion model of gas sputtering
International Nuclear Information System (INIS)
Hotston, E.S.
1980-01-01
A model is proposed to explain the experimental results on deuteron trapping in stainless steel targets at low temperatures carried out at Garching and Culham. The model proposes that the ions are trapped in two kinds of sites: Deep sites with high activation energy and shallow sites of low activation energy. Trapped deuterons reach the surface of the target by being expelled from shallow sites by the action of the ion beam and migrate to nearby sites in a random way, thus moving by a bombardment induced diffusion. Ions diffusing to the target surface and being released are said to be sputtered from the target. It has been necessary to assume numerical values for sizes of some of the processes which occur. With a suitable choice of values the model successfully predicts the numbers of deuterons trapped per unit area of the target, the obserbed density profile of the trapped ions and the threshold at which sputtering starts. The model also successfully describes the replacement of the trapped deuterons by protons, when the deuteron beam is replaced by a proton beam. The collision cross-section for beam ions and ions trapped in shallow sites is too large, 4 x 10 -13 cm 2 , for a binary collision and it is tentatively suggested that the ions in the shallow sites may be in small voids in the target which may be connected with blister formation. Comparison of the present model with one being developed to describe the trapping of deuterons in carbon suggests that it may be possible to describe all gas sputtering experiments in terms of diffusion processes. (orig.)
Diffusion induced flow on a wedge-shaped obstacle
International Nuclear Information System (INIS)
Zagumennyi, Ia V; Dimitrieva, N F
2016-01-01
In this paper the problem of evolution of diffusion induced flow on a wedge-shaped obstacle is analyzed numerically. The governing set of fundamental equations is solved using original solvers from the open source OpenFOAM package on supercomputer facilities. Due to breaking of naturally existing diffusion flux of a stratifying agent by the impermeable surface of the wedge a complex multi-level vortex system of compensatory fluid motions is formed around the obstacle. Sharp edges of the obstacle generate extended high-gradient horizontal interfaces which are clearly observed in laboratory experiments by high-resolution Schlieren visualization. Formation of an intensive pressure depression zone in front of the leading vertex of the wedge is responsible for generation of propulsive force resulting in a self-displacement of the obstacle along the neutral buoyancy horizon in a stably stratified environment. The size of the pressure deficiency area near the sharp vertex of a concave wedge is about twice that for a convex one. This demonstrates a more intensive propulsion mechanism in case of the concave wedge and, accordingly, a higher velocity of its self-movement in a continuously stratified medium. (paper)
Phonon-induced anomalous Raman spectra in undoped high-Tc cuprates
International Nuclear Information System (INIS)
Lee, J.D.; Min, B.I.
1997-01-01
In order to describe a shoulder peak structure near 4J in the magnon Raman spectra of undoped high-T c cuprates, we have explored the phonon contribution to the Raman spectra. Incorporating the magnon-phonon Hamiltonian in the spin-wave theory, we have evaluated the two-magnon Raman spectral function originating from the lowest-order magnon-phonon-magnon scattering. It is found that phonons induce a shoulder peak near 4J besides the dominant two-magnon peak near 3J, in agreement with experiments. (orig.)
Light-Induced Type-II Band Inversion and Quantum Anomalous Hall State in Monolayer FeSe
Wang, Z. F.; Liu, Zhao; Yang, Jinlong; Liu, Feng
2018-04-01
Coupling a quantum anomalous Hall (QAH) state with a superconducting state offers an attractive approach to detect the signature alluding to a topological superconducting state [Q. L. He et al., Science 357, 294 (2017), 10.1126/science.aag2792], but its explanation could be clouded by disorder effects in magnetic doped QAH materials. On the other hand, an antiferromagnetic (AFM) quantum spin Hall (QSH) state is identified in the well-known high-temperature 2D superconductor of monolayer FeSe [Z. F. Wang et al., Nat. Mater. 15, 968 (2016), 10.1038/nmat4686]. Here, we report a light-induced type-II band inversion (BI) and a QSH-to-QAH phase transition in the monolayer FeSe. Depending on the handedness of light, a spin-tunable QAH state with a high Chern number of ±2 is realized. In contrast to the conventional type-I BI resulting from intrinsic spin-orbital coupling (SOC), which inverts the band an odd number of times and respects time reversal symmetry, the type-II BI results from a light-induced handedness-dependent effective SOC, which inverts the band an even number of times and does not respect time reversal symmetry. The interplay between these two SOC terms makes the spin-up and -down bands of an AFM QSH state respond oppositely to a circularly polarized light, leading to the type-II BI and an exotic topological phase transition. Our finding affords an exciting opportunity to detect Majorana fermions in one single material without magnetic doping.
Application of aluminum diffusion coatings to mitigate the KCl-induced high-temperature corrosion
DEFF Research Database (Denmark)
Kiamehr, Saeed; Lomholt, T. N.; Dahl, Kristian Vinter
2017-01-01
Pack cementation was used to produce Fe1−xAl and Fe2Al5 diffusion coatings on ferritic-martensitic steel P91 and a Ni2Al3 diffusion coating on pure nickel. The performance of diffusion coatings against high-temperature corrosion induced by potassium chloride (KCl) was evaluated by exposing...
Directory of Open Access Journals (Sweden)
Philip R Corlett
2009-11-01
Full Text Available The salience hypothesis of psychosis rests on a simple but profound observation that subtle alterations in the way that we perceive and experience stimuli have important consequences for how important these stimuli become for us, how much they draw our attention, how they embed themselves in our memory and, ultimately, how they shape our beliefs. We put forward the idea that a classical memory illusion – the Deese-Roediger-McDermott (DRM effect – offers a useful way of exploring processes related to such aberrant belief formation. The illusion occurs when, as a consequence of its relationship to previous stimuli, a stimulus is asserted to be remembered even when has not been previously presented. Such illusory familiarity is thought to be generated by the surprising fluency with which the stimulus is processed. In this respect, the illusion relates directly to the salience hypothesis and may share common cognitive underpinnings with aberrations of perception and attribution that are found in psychosis. In this paper, we explore the theoretical importance of this experimentally-induced illusion in relation to the salience model of psychosis. We present data showing that, in healthy volunteers, the illusion relates directly to self reported anomalies of experience and magical thinking. We discuss this finding in terms of the salience hypothesis and of a broader Bayesian framework of perception and cognition which emphasizes the salience both of predictable and unpredictable experiences..
AC electric field induced vortex in laminar coflow diffusion flames
Xiong, Yuan; Cha, Min; Chung, Suk-Ho
2014-01-01
Experiments were performed by applying sub-critical high-voltage alternating current (AC) to the nozzle of laminar propane coflow diffusion flames. Light scattering, laser-induced incandescence and laser-induced fluorescence techniques were used to identify the soot zone, and the structures of OH and polycyclic aromatic hydrocarbons (PAHs). Particle image velocimetry was adopted to quantify the velocity field. Under certain AC conditions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex. The onset conditions for the vortex formation supported the role of an electromagnetic force acting on charged particles in the flame zone. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
AC electric field induced vortex in laminar coflow diffusion flames
Xiong, Yuan
2014-09-22
Experiments were performed by applying sub-critical high-voltage alternating current (AC) to the nozzle of laminar propane coflow diffusion flames. Light scattering, laser-induced incandescence and laser-induced fluorescence techniques were used to identify the soot zone, and the structures of OH and polycyclic aromatic hydrocarbons (PAHs). Particle image velocimetry was adopted to quantify the velocity field. Under certain AC conditions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered, leading to the formation of toroidal vortices. Increased residence time and heat recirculation inside the vortex resulted in appreciable formation of PAHs and soot near the nozzle exit. Decreased residence time along the jet axis through flow acceleration by the vortex led to a reduction in the soot volume fraction in the downstream sooting zone. Electromagnetic force generated by AC was proposed as a viable mechanism for the formation of the toroidal vortex. The onset conditions for the vortex formation supported the role of an electromagnetic force acting on charged particles in the flame zone. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
A critical discussion of the vacancy diffusion model of ion beam induced epitaxial crystallization
International Nuclear Information System (INIS)
Heera, V.
1989-01-01
A simple vacancy diffusion model of ion beam induced epitaxial crystallization of silicon including divacancy formation is developed. The model reproduces some of the experimental findings, as e.g. the dose rate dependence of the crystallization rate. However, the measured activation energy of the ion beam induced epitaxial crystallization cannot be accounted for by vacancy diffusion alone. (author)
Gas-induced friction and diffusion of rigid rotors
Martinetz, Lukas; Hornberger, Klaus; Stickler, Benjamin A.
2018-05-01
We derive the Boltzmann equation for the rotranslational dynamics of an arbitrary convex rigid body in a rarefied gas. It yields as a limiting case the Fokker-Planck equation accounting for friction, diffusion, and nonconservative drift forces and torques. We provide the rotranslational friction and diffusion tensors for specular and diffuse reflection off particles with spherical, cylindrical, and cuboidal shape, and show that the theory describes thermalization, photophoresis, and the inverse Magnus effect in the free molecular regime.
New macroscopic theory of anamalous diffusion induced by the dissipative trapped-ion instability
International Nuclear Information System (INIS)
Wimmel, H.K.
1975-03-01
For an axisymmetric toroidal plasma of the TOKAMAK type a new set of dissipative trapped-fluid equations is established. In addition to E vector x B vector drifts and collisions of the trapped particles, these equations take full account of the effect of Esub(//) (of the trapped ion modes) on free and trapped particles, and of the effect of grad delta 0 (delta 0 = equilibrium fraction of trapped particles). From the new equations the linear-mode properties of the dissipative trapped-ion instability and the anomalous diffusion flux of the trapped particles are derived. (orig.) [de
Diffusion processes in bombardment-induced surface topography
International Nuclear Information System (INIS)
Robinson, R.S.
1984-01-01
A treatment is given of the problem of surface diffusion processes occurring during surface topography development, whenever a surface is simultaneously seeded with impurities and ion bombarded. The development of controllable topography and the importance of surface diffusion parameters, which can be obtained during these studies, are also analyzed. 101 refs.; 7 figs.; 2 tabs
Experimental Investigation of Radio-Turbulence Induced Diffusion -- Final Report
Energy Technology Data Exchange (ETDEWEB)
Spitz, H. B.; Usman, S.
2005-07-07
The outcome of this research project suggests that the transport of radon in water is significantly greater than that predicted solely by molecular diffusion. The original study was related to the long term storage of {sup 226}Ra-bearing sand at the DOE Fernald site and determining whether a barrier of water covering the sand would be effective in reducing the emanation of {sup 222}Rn from the sand. Initial observations before this study found the transport of radon in water to be greater than that predicted solely by molecular diffusion. Fick's law on diffusion was used to model the transport of radon in water including the impact associated with radioactive decay. Initial measurements suggested that the deposition of energy in water associated with the radioactive decay process influences diffusion and enhances transport of radon. A multi-region, one-dimensional, steady-state transport model was used to analyze the movement of radon through a sequential column of air, water and air. An effective diffusion coefficient was determined by varying the thickness of the water column and measuring the time for transport of {sup 222}Rn through of the water barrier. A one-region, one-dimensional transient diffusion equation was developed to investigate the build up of radon at the end of the water column to the time when a steady-state, equilibrium condition was achieved. This build up with time is characteristic of the transport rate of radon in water and established the basis for estimating the effective diffusion coefficient for {sup 222}Rn in water. Several experiments were conducted using different types and physical arrangements of water barriers to examine how radon transport is influenced by the water barrier. Results of our measurements confirm our theoretical analyses which suggest that convective forces other than pure molecular diffusion impact the transport of {sup 222}Rn through the water barrier. An effective diffusion coefficient is defined that
Influence of residual stress on diffusion-induced bending in bilayered microcantilever sensors
International Nuclear Information System (INIS)
Xuan Fuzhen; Shao Shanshan; Wang Zhengdong; Tu Shantung
2010-01-01
The influence of residual stress on diffusion-induced bending in bilayered microcantilever sensors has been analyzed under the framework of thermodynamic theory and Fick's second law. A self-consistent diffusion equation involving the coupling effects of residual stress and diffusion-induced stress is developed. Effects of thickness ratio, modulus ratio, diffusivity ratio and residual stress gradient of film and substrate on the curvature of bilayered cantilever are then discussed with the help of finite difference method. Results reveal that the curvature of bilayered cantilever increases with decreasing the diffusivity ratio and modulus ratio of substrate to film at a given time. Case study of the polysilicon/palladium hydrogen sensor has been finally carried out using the above developed bending theory.
Temple, Blake; Smoller, Joel
2009-08-25
We derive a system of three coupled equations that implicitly defines a continuous one-parameter family of expanding wave solutions of the Einstein equations, such that the Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology is embedded as a single point in this family. By approximating solutions near the center to leading order in the Hubble length, the family reduces to an explicit one-parameter family of expanding spacetimes, given in closed form, that represents a perturbation of the Standard Model. By introducing a comoving coordinate system, we calculate the correction to the Hubble constant as well as the exact leading order quadratic correction to the redshift vs. luminosity relation for an observer at the center. The correction to redshift vs. luminosity entails an adjustable free parameter that introduces an anomalous acceleration. We conclude (by continuity) that corrections to the redshift vs. luminosity relation observed after the radiation phase of the Big Bang can be accounted for, at the leading order quadratic level, by adjustment of this free parameter. The next order correction is then a prediction. Since nonlinearities alone could actuate dissipation and decay in the conservation laws associated with the highly nonlinear radiation phase and since noninteracting expanding waves represent possible time-asymptotic wave patterns that could result, we propose to further investigate the possibility that these corrections to the Standard Model might be the source of the anomalous acceleration of the galaxies, an explanation not requiring the cosmological constant or dark energy.
A magnetic gradient induced force in NMR restricted diffusion experiments
International Nuclear Information System (INIS)
Ghadirian, Bahman; Stait-Gardner, Tim; Castillo, Reynaldo; Price, William S.
2014-01-01
We predict that the phase cancellation of a precessing magnetisation field carried by a diffusing species in a bounded geometry under certain nuclear magnetic resonance pulsed magnetic field gradient sequences results in a small force over typically micrometre length scales. Our calculations reveal that the total magnetisation energy in a pore under the influence of a pulsed gradient will be distance-dependent thus resulting in a force acting on the boundary. It is shown that this effect of the magnetisation of diffusing particles will appear as either an attractive or repulsive force depending on the geometry of the pore and magnetic properties of the material. A detailed analysis is performed for the case of a pulsed gradient spin-echo experiment on parallel planes. It is shown that the force decays exponentially in terms of the spin-spin relaxation. The proof is based on classical electrodynamics. An application of this effect to soft matter is suggested
International Nuclear Information System (INIS)
Zhang, Tao; Guo, Zhansheng
2014-01-01
The effects of electrode properties and fabricated pressure on Li ion diffusion and diffusion-induced stress in a cylindrical Li-ion battery are studied. It is found that hydrostatic pressure or elastic modulus variation in the active layer have little effect on the distribution of Li ions for a higher diffusivity coefficient, but both can facilitate Li ion diffusion for a lower diffusivity coefficient. The elastic modulus variation has a significant effect on the distribution of stress and hydrostatic pressure can reduce the surface stress for the lower diffusivity coefficient. A higher charging rate causes a more transient response in the stress history, but a linear charging history is observed for slow charging rates. A higher charging rate would not inflict extra damage on the electrode for the higher diffusivity coefficient and the stress history becomes highly transient and charging rate dependent for the lower diffusivity coefficient. The effect of fabricated pressure can be neglected. (paper)
Directory of Open Access Journals (Sweden)
H. F. Li
2014-12-01
Full Text Available Using density functional theory (DFT method combined with non-equilibrium Green’s function approach, we systematically investigated the structural, ferroelectric and electronic transport properties of Pt/BaTiO3/Pt ferroelectric tunnel junctions (FTJ with the interface atomic layers doped by charge neutral NbTi substitution. It is found that interfacial NbTi substitution will produce several anomalous effects such as the vanishing of ferroelectric critical thickness and the decrease of junction resistance against tunneling current. Consequently, the thickness of the ferroelectric thin film (FTF in the FTJ can be reduced, and both the electroresistance effect and sensitivity to external bias of the FTJ are enhanced. Our calculations indicate that the enhancements of conductivity and ferroelectric distortion can coexist in FTJs, which should be important for applications of functional electronic devices based on FTJs.
Circulation induced by diffused aeration in a shallow lake
African Journals Online (AJOL)
2017-01-01
Jan 1, 2017 ... Lastly, a simple returning flow model was proposed to describe the circulation flow patterns ... method to describe the circulation patterns induced by the bub- ... 160 holes of 1 mm, which was designed to promote high mix-.
Radial diffusion of toroidally trapped particles induced by lower hybrid and fast waves
International Nuclear Information System (INIS)
Krlin, L.
1992-10-01
The interaction of RF field with toroidally trapped particles (bananas) can cause their intrinsic stochastically diffusion both in the configuration and velocity space. In RF heating and/or current drive regimes, RF field can interact with plasma particles and with thermonuclear alpha particles. The aim of this contribution is to give some analytical estimates of induced radial diffusion of alphas and of ions. (author)
Energy Technology Data Exchange (ETDEWEB)
Fowler, T. K.; Guest, G. E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)
1966-04-15
We discuss radial plasma transport in magnetic wells (magnetic gradient dB/dr > 0) with particular attention to low frequency instabilities not stabilized by the positive gradient ({omega} ' {omega}{sub ci}, k{rho} ' 1). We take {beta} small. The unperturbed plasma departs from thermal equilibrium only in the azimuthal current-and radial pressure profile inherent in confinement. If dB/dr > 0 and {Delta}B = R(dB/dr) > B(T{sub e}/T{sub i}), the ExB ''diffusion'' coefficient is (1) D{sub Up-Tack} {<=} (cT{sub /}eB )({rho}{sub i}/R) (T{sub e}/T{sub i} + m{sub e}/m{sub i}) Vulgar-Fraction-One-Half where {rho}{sub i} is the ion gyroradius and R is the plasma radius. If dB/dr is only positive on the average, there is an additional requirement that L/R < (T{sub i}/T{sub e}) Vulgar-Fraction-One-Half , where L is the length along B over which dB/dr is negative. Applications to various thermonuclear magnetic confinement geometries are discussed. Results in some cases are encouraging and complement our previous conclusion that stochastic diffusion is also tolerable for fusion. Open questions are the {beta} limit and the non-linear behavior of certain velocity-space instabilities at {omega} {>=} {omega}{sub ci}. the ion gyrofrequency. In deriving eq. 1, we take D{sub Up-Tack} = {lambda}(cE{sub Up-Tack }/B), where {lambda} is a radial ''mixing length''. We estimate E{sub Up-Tack} from the available free energy composed of two terms, {delta}W = {delta}W{sub 0} + {delta}W{sub 1}, the first term, {delta}W{sub 0}, is the usual stabilizing term in a magnetic well, or an ''average'' well, if the magnetic moment {mu} and the longitudinal invariant J are conserved. The term {delta}W, accounts for violations of adiabatic invariance. We estimate it from nonlinear thermodynamics. There can be a large positive contribution to {delta}W from the relaese of thermal energy in a manner analogous to expansion cooling of a gas, which accounts for anomalous diffusion in several experiments where d
Laser-induced diffusion decomposition in Fe–V thin-film alloys
Energy Technology Data Exchange (ETDEWEB)
Polushkin, N.I., E-mail: nipolushkin@fc.ul.pt [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Duarte, A.C.; Conde, O. [Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Alves, E. [Associação Euratom/IST e Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS (Portugal); García-García, A.; Kakazei, G.N.; Ventura, J.O.; Araujo, J.P. [Departamento de Física, Universidade do Porto e IFIMUP, 4169-007 Porto (Portugal); Oliveira, V. [Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa, 1959-007 Lisboa (Portugal); Vilar, R. [Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Instituto de Ciência e Engenharia de Materiais e Superfícies, 1049-001 Lisboa (Portugal)
2015-05-01
Highlights: • Irradiation of an Fe–V alloy by femtosecond laser triggers diffusion decomposition. • The decomposition occurs with strongly enhanced (∼4 orders) atomic diffusivity. • This anomaly is associated with the metallic glassy state achievable under laser quenching. • The ultrafast diffusion decomposition is responsible for laser-induced ferromagnetism. - Abstract: We investigate the origin of ferromagnetism induced in thin-film (∼20 nm) Fe–V alloys by their irradiation with subpicosecond laser pulses. We find with Rutherford backscattering that the magnetic modifications follow a thermally stimulated process of diffusion decomposition, with formation of a-few-nm-thick Fe enriched layer inside the film. Surprisingly, similar transformations in the samples were also found after their long-time (∼10{sup 3} s) thermal annealing. However, the laser action provides much higher diffusion coefficients (∼4 orders of magnitude) than those obtained under standard heat treatments. We get a hint that this ultrafast diffusion decomposition occurs in the metallic glassy state achievable in laser-quenched samples. This vitrification is thought to be a prerequisite for the laser-induced onset of ferromagnetism that we observe.
Ogieglo, Wojciech; Wormeester, Herbert; Wessling, Matthias; Benes, Nieck Edwin
2013-01-01
In situ time-resolved spectroscopic ellipsometry is used to study the dynamics of n-hexane diffusion into, and the corresponding induced swelling of, ultra-thin polystyrene films. The experimental conditions are carefully selected to facilitate the observation of anomalous Case II diffusion in the
Directory of Open Access Journals (Sweden)
Pranab Biswas
2014-05-01
Full Text Available The diffusion behavior of arsenic (As and gallium (Ga atoms from semi-insulating GaAs (SI-GaAs into ZnO films upon post-growth annealing vis-à-vis the resulting charge compensation was investigated with the help of x-ray photoelectron spectroscopy (XPS and secondary ion mass spectroscopy. The films, annealed at 600 ºC and 700 ºC showed p-type conductivity with a hole concentration of 1.1 × 1018 cm−3 and 2.8 × 1019 cm−3 respectively, whereas those annealed at 800 ºC showed n-type conductivity with a carrier concentration of 6.5 × 1016 cm−3. It is observed that at lower temperatures, large fraction of As atoms diffused from the SI-GaAs substrates into ZnO and formed acceptor related complex, (AsZn–2VZn, by substituting Zn atoms (AsZn and thereby creating two zinc vacancies (VZn. Thus as-grown ZnO which was supposed to be n-type due to nonstoichiometric nature showed p-type behavior. On further increasing the annealing temperature to 800 ºC, Ga atoms diffused more than As atoms and substitute Zn atoms thereby forming shallow donor complex, GaZn. Electrons from donor levels then compensate the p-type carriers and the material reverts back to n-type. Thus the conversion of carrier type took place due to charge compensation between the donors and acceptors in ZnO and this compensation is the possible origin of anomalous conduction in wide band gap materials.
Diffusive Imaging of Hydraulically Induced and Natural Fracture Systems
Eftekhari, B.; Marder, M. P.; Patzek, T. W.
2017-12-01
Hydraulic fracturing of tight shales continues to provide the US with a major source of energy. Efficiency of gas recovery in shales depends upon the geometry of the resulting network of fractures, the details of which are not yet fully understood. The present research explores how much of the underlying geometry can be deduced from the time dependence of the flow of gas out of the reservoir. We consider both ideal and real gas. In the case of real gas, we calculate production rate for parallel planar hydrofractures embedded in an infinite reservoir. Transport is governed by a nonlinear diffusion equation, which we solve exactly with a scaling curve. The scaling curve production rate declines initially as 1 over square root time, then as an exponential, and finally as 1 over square root of time again at late time. We show that for a given hydraulically fractured well, the onsets of transition between different decline regimes provides a direct estimate of a characteristic spacing of the underlying fracture network. We show that the scaling solution accurately fits the production history of more than 15,000 wells in the Barnett Shale. Almost all of the wells either have not yet transitioned into the late time decline or have been refractured while in exponential decline. However, there are 36 wells which show the late time transition. These allow us to calculate the characteristic spacing, which turns out to have a mode at about 10 m, a minimum at 1.6 m and a maximum at 13.3 m. We estimate that over 30 years these wells will produce on average about 45% more gas because of diffusion from the infinite external reservoir than they would if this contribution is neglected. Finally, we compute the rate at which ideal gas diffuses within an infinite region of rock into a specific absorbing fractal fracture network, which we model using geological constraints and percolation theory. Our solution employs a Brownian walk and the first passage kinetic Monte Carlo algorithm
Anomalous magnetic moment with heavy virtual leptons
Energy Technology Data Exchange (ETDEWEB)
Kurz, Alexander [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Liu, Tao; Steinhauser, Matthias [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Marquard, Peter [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2013-11-15
We compute the contributions to the electron and muon anomalous magnetic moment induced by heavy leptons up to four-loop order. Asymptotic expansion is applied to obtain three analytic expansion terms which show rapid convergence.
Yan, Peng; Huang, Jin; Lu, Run-Chao; Jin, Chen; Xiao, Jin-Xin; Chen, Yong-Ming
2005-03-24
This paper reported the phase behavior and aggregate structure of tetrabutylammonium perfluorooctanoate (TBPFO), determined by differential scanning calorimeter, electrical conductivity, static/dynamic light scattering, and rheology methods. We found that above a certain concentration the TBPFO solution showed anomalous temperature-dependent phase behavior and structure transitions. Such an ionic surfactant solution exhibits two cloud points. When the temperature was increased, the solution turned from a homogeneous-phase to a liquid-liquid two-phase system, then to another homogeneous-phase, and finally to another liquid-liquid two-phase system. In the first homogeneous-phase region, the aggregates of TBPFO were rodlike micelles and the solution was Newtonian fluid. While in the second homogeneous-phase region, the aggregates of TBPFO were large wormlike micelles, and the solution behaved as pseudoplastic fluid that also exhibited viscoelastic behavior. We thought that the first cloud point might be caused by the "bridge" effect of the tetrabutylammonium counterion between the micelles and the second one by the formation of the micellar network.
Heterogeneity induces spatiotemporal oscillations in reaction-diffusion systems
Krause, Andrew L.; Klika, Václav; Woolley, Thomas E.; Gaffney, Eamonn A.
2018-05-01
We report on an instability arising in activator-inhibitor reaction-diffusion (RD) systems with a simple spatial heterogeneity. This instability gives rise to periodic creation, translation, and destruction of spike solutions that are commonly formed due to Turing instabilities. While this behavior is oscillatory in nature, it occurs purely within the Turing space such that no region of the domain would give rise to a Hopf bifurcation for the homogeneous equilibrium. We use the shadow limit of the Gierer-Meinhardt system to show that the speed of spike movement can be predicted from well-known asymptotic theory, but that this theory is unable to explain the emergence of these spatiotemporal oscillations. Instead, we numerically explore this system and show that the oscillatory behavior is caused by the destabilization of a steady spike pattern due to the creation of a new spike arising from endogeneous activator production. We demonstrate that on the edge of this instability, the period of the oscillations goes to infinity, although it does not fit the profile of any well-known bifurcation of a limit cycle. We show that nearby stationary states are either Turing unstable or undergo saddle-node bifurcations near the onset of the oscillatory instability, suggesting that the periodic motion does not emerge from a local equilibrium. We demonstrate the robustness of this spatiotemporal oscillation by exploring small localized heterogeneity and showing that this behavior also occurs in the Schnakenberg RD model. Our results suggest that this phenomenon is ubiquitous in spatially heterogeneous RD systems, but that current tools, such as stability of spike solutions and shadow-limit asymptotics, do not elucidate understanding. This opens several avenues for further mathematical analysis and highlights difficulties in explaining how robust patterning emerges from Turing's mechanism in the presence of even small spatial heterogeneity.
Delay-induced wave instabilities in single-species reaction-diffusion systems
Otto, Andereas; Wang, Jian; Radons, Günter
2017-11-01
The Turing (wave) instability is only possible in reaction-diffusion systems with more than one (two) components. Motivated by the fact that a time delay increases the dimension of a system, we investigate the presence of diffusion-driven instabilities in single-species reaction-diffusion systems with delay. The stability of arbitrary one-component systems with a single discrete delay, with distributed delay, or with a variable delay is systematically analyzed. We show that a wave instability can appear from an equilibrium of single-species reaction-diffusion systems with fluctuating or distributed delay, which is not possible in similar systems with constant discrete delay or without delay. More precisely, we show by basic analytic arguments and by numerical simulations that fast asymmetric delay fluctuations or asymmetrically distributed delays can lead to wave instabilities in these systems. Examples, for the resulting traveling waves are shown for a Fisher-KPP equation with distributed delay in the reaction term. In addition, we have studied diffusion-induced instabilities from homogeneous periodic orbits in the same systems with variable delay, where the homogeneous periodic orbits are attracting resonant periodic solutions of the system without diffusion, i.e., periodic orbits of the Hutchinson equation with time-varying delay. If diffusion is introduced, standing waves can emerge whose temporal period is equal to the period of the variable delay.
Russo, Giovanni; Shorten, Robert
2018-04-01
This paper is concerned with the study of common noise-induced synchronization phenomena in complex networks of diffusively coupled nonlinear systems. We consider the case where common noise propagation depends on the network state and, as a result, the noise diffusion process at the nodes depends on the state of the network. For such networks, we present an algebraic sufficient condition for the onset of synchronization, which depends on the network topology, the dynamics at the nodes, the coupling strength and the noise diffusion. Our result explicitly shows that certain noise diffusion processes can drive an unsynchronized network towards synchronization. In order to illustrate the effectiveness of our result, we consider two applications: collective decision processes and synchronization of chaotic systems. We explicitly show that, in the former application, a sufficiently large noise can drive a population towards a common decision, while, in the latter, we show how common noise can synchronize a network of Lorentz chaotic systems.
Laser-induced desorption determinations of surface diffusion on Rh(111)
International Nuclear Information System (INIS)
Seebauer, E.G.; Schmidt, L.D.
1987-01-01
Surface diffusion of hydrogen, deuterium and CO on Rh(111) has been investigated by laser-induced thermal desorption (LITD) and compared with previous results for these species on Pt(111) and on other metals. For deuterium in the coverage range 0.02 0 - 8 x 10 -2 cm 2 /s, with a diffusion activation energy 3.7 0 rises from 10 -3 to 10 -2 cm 2 /s between θ = 0.01 and 0.40. Values of E/sub diff/ on different surfaces appear to correlate with differences in heats of adsorption in different binding states which form saddle point configurations in surface diffusion. In addition, oxidation reactions on Rh and on several other transition metal surfaces may be limited to CO or H surface diffusion. 30 refs., 3 figs., 1 tab
The Induced Dimension Reduction method applied to convection-diffusion-reaction problems
Astudillo, R.; Van Gijzen, M.B.
2016-01-01
Discretization of (linearized) convection-diffusion-reaction problems yields a large and sparse non symmetric linear system of equations, Ax = b. (1) In this work, we compare the computational behavior of the Induced Dimension Reduction method (IDR(s)) [10], with other short-recurrences Krylov
Persistent wind-induced enhancement of diffusive CO2 transport in a mountain forest snowpack
D. R. Bowling; W. J. Massman
2011-01-01
Diffusion dominates the transport of trace gases between soil and the atmosphere. Pressure gradients induced by atmospheric flow and wind interacting with topographical features cause a small but persistent bulk flow of air within soil or snow. This forcing, called pressure pumping or wind pumping, leads to a poorly quantified enhancement of gas transport beyond the...
Anomalous transport from holography. Part I
Energy Technology Data Exchange (ETDEWEB)
Bu, Yanyan [Department of Physics, Ben-Gurion University of the Negev,Beer-Sheva 84105 (Israel); Lublinsky, Michael [Department of Physics, Ben-Gurion University of the Negev,Beer-Sheva 84105 (Israel); Physics Department, University of Connecticut,2152 Hillside Road, Storrs, CT 06269-3046 (United States); Sharon, Amir [Department of Physics, Ben-Gurion University of the Negev,Beer-Sheva 84105 (Israel)
2016-11-17
We revisit the transport properties induced by the chiral anomaly in a charged plasma holographically dual to anomalous U(1){sub V}×U(1){sub A} Maxwell theory in Schwarzschild-AdS{sub 5}. Off-shell constitutive relations for vector and axial currents are derived using various approximations generalising most of known in the literature anomaly-induced phenomena and revealing some new ones. In a weak external field approximation, the constitutive relations have all-order derivatives resummed into six momenta-dependent transport coefficient functions: the diffusion, the electric/magnetic conductivity, and three anomaly induced functions. The latter generalise the chiral magnetic and chiral separation effects. Nonlinear transport is studied assuming presence of constant background external fields. The chiral magnetic effect, including all order nonlinearity in magnetic field, is proven to be exact when the magnetic field is the only external field that is turned on. Non-linear corrections to the constitutive relations due to electric and axial external fields are computed.
Anomalous transport from holography. Pt. II
International Nuclear Information System (INIS)
Bu, Yanyan; Sharon, Amir; Lublinsky, Michael
2017-01-01
This is a second study of chiral anomaly-induced transport within a holographic model consisting of anomalous U(1)_V x U(1)_A Maxwell theory in Schwarzschild-AdS_5 spacetime. In the first part, chiral magnetic/separation effects (CME/CSE) are considered in the presence of a static spatially inhomogeneous external magnetic field. Gradient corrections to CME/CSE are analytically evaluated up to third order in the derivative expansion. Some of the third order gradient corrections lead to an anomaly-induced negative B"2-correction to the diffusion constant. We also find modifications to the chiral magnetic wave nonlinear in B. In the second part, we focus on the experimentally interesting case of the axial chemical potential being induced dynamically by a constant magnetic and time-dependent electric fields. Constitutive relations for the vector/axial currents are computed employing two different approximations: (a) derivative expansion (up to third order) but fully nonlinear in the external fields, and (b) weak electric field limit but resuming all orders in the derivative expansion. A non-vanishing nonlinear axial current (CSE) is found in the first case. The dependence on magnetic field and frequency of linear transport coefficient functions is explored in the second. (orig.)
Anomalous transport from holography. Pt. II
Energy Technology Data Exchange (ETDEWEB)
Bu, Yanyan; Sharon, Amir [Ben-Gurion University of the Negev, Department of Physics, Beersheba (Israel); Lublinsky, Michael [Ben-Gurion University of the Negev, Department of Physics, Beersheba (Israel); University of Connecticut, Physics Department, Storrs, CT (United States)
2017-03-15
This is a second study of chiral anomaly-induced transport within a holographic model consisting of anomalous U(1){sub V} x U(1){sub A} Maxwell theory in Schwarzschild-AdS{sub 5} spacetime. In the first part, chiral magnetic/separation effects (CME/CSE) are considered in the presence of a static spatially inhomogeneous external magnetic field. Gradient corrections to CME/CSE are analytically evaluated up to third order in the derivative expansion. Some of the third order gradient corrections lead to an anomaly-induced negative B{sup 2}-correction to the diffusion constant. We also find modifications to the chiral magnetic wave nonlinear in B. In the second part, we focus on the experimentally interesting case of the axial chemical potential being induced dynamically by a constant magnetic and time-dependent electric fields. Constitutive relations for the vector/axial currents are computed employing two different approximations: (a) derivative expansion (up to third order) but fully nonlinear in the external fields, and (b) weak electric field limit but resuming all orders in the derivative expansion. A non-vanishing nonlinear axial current (CSE) is found in the first case. The dependence on magnetic field and frequency of linear transport coefficient functions is explored in the second. (orig.)
Anomalous transport from holography. Part I
International Nuclear Information System (INIS)
Bu, Yanyan; Lublinsky, Michael; Sharon, Amir
2016-01-01
We revisit the transport properties induced by the chiral anomaly in a charged plasma holographically dual to anomalous U(1)_V×U(1)_A Maxwell theory in Schwarzschild-AdS_5. Off-shell constitutive relations for vector and axial currents are derived using various approximations generalising most of known in the literature anomaly-induced phenomena and revealing some new ones. In a weak external field approximation, the constitutive relations have all-order derivatives resummed into six momenta-dependent transport coefficient functions: the diffusion, the electric/magnetic conductivity, and three anomaly induced functions. The latter generalise the chiral magnetic and chiral separation effects. Nonlinear transport is studied assuming presence of constant background external fields. The chiral magnetic effect, including all order nonlinearity in magnetic field, is proven to be exact when the magnetic field is the only external field that is turned on. Non-linear corrections to the constitutive relations due to electric and axial external fields are computed.
Zhang, Chuang; Sun, Dali; Yu, Zhi-Gang; Sheng, Chuan-Xiang; McGill, Stephen; Semenov, Dmitry; Vardeny, Zeev Valy
2018-04-01
The organic-inorganic hybrid perovskites show excellent optical and electrical properties for photovoltaic and a myriad of other optoelectronics applications. Using high-field magneto-optical measurements up to 17.5 T at cryogenic temperatures, we have studied the spin-dependent optical transitions in the prototype C H3N H3Pb I3 , which are manifested in the field-induced circularly polarized photoluminescence emission. The energy splitting between left and right circularly polarized emission bands is measured to be ˜1.5 meV at 17.5 T, from which we obtained an exciton effective g factor of ˜1.32. Also from the photoluminescence diamagnetic shift we estimate the exciton binding energy to be ˜17 meV at low temperature. Surprisingly, the corresponding field-induced circular polarization is "anomalous" in that the photoluminescence emission of the higher split energy band is stronger than that of the lower split band. This "reversed" intensity ratio originates from the combination of long electron spin relaxation time and hole negative g factor in C H3N H3Pb I3 , which are in agreement with a model based on the k.p effective-mass approximation.
Anomalous magnetohydrodynamics in the extreme relativistic domain
Giovannini, Massimo
2016-01-01
The evolution equations of anomalous magnetohydrodynamics are derived in the extreme relativistic regime and contrasted with the treatment of hydromagnetic nonlinearities pioneered by Lichnerowicz in the absence of anomalous currents. In particular we explore the situation where the conventional vector currents are complemented by the axial-vector currents arising either from the pseudo Nambu-Goldstone bosons of a spontaneously broken symmetry or because of finite fermionic density effects. After expanding the generally covariant equations in inverse powers of the conductivity, the relativistic analog of the magnetic diffusivity equation is derived in the presence of vortical and magnetic currents. While the anomalous contributions are generally suppressed by the diffusivity, they are shown to disappear in the perfectly conducting limit. When the flow is irrotational, boost-invariant and with vanishing four-acceleration the corresponding evolution equations are explicitly integrated so that the various physic...
Productivity effects of technology diffusion induced by an energy tax
International Nuclear Information System (INIS)
Walz, R.
1999-01-01
In the political discussion, the economy-wide effects of an energy tax have gained considerable attention. So far, macroeconomic analyses have focused on either (positive or negative) costs triggered by an energy tax, or on the efficiency gains resulting from new energy taxes combined with lower distortionary taxes. By contrast, the innovative effects of climate protection measures have not yet been thoroughly analysed. This paper explores the productivity effects of a 50 per cent energy tax in the German industry sector employing a technology-based, three-step bottom-up approach. In the first step, the extensive IKARUS database is used to identify the technological adjustments arising from an energy tax. In the second step, the technologies are classified into different clusters. In the third step, the productivity effects generated by the technological adjustments are examined. The results imply that an energy tax induces mainly sector-specific and process-integrated technologies rather than add-on and cross-cutting technologies. Further, it is shown that the energy-saving technologies tend to increase productivity. This is particularly the case for process-integrated, sector specific technologies. (author)
The effect of diffusion induced lattice stress on the open-circuit voltage in silicon solar cells
Weizer, V. G.; Godlewski, M. P.
1984-01-01
It is demonstrated that diffusion induced stresses in low resistivity silicon solar cells can significantly reduce both the open-circuit voltage and collection efficiency. The degradation mechanism involves stress induced changes in both the minority carrier mobility and the diffusion length. Thermal recovery characteristics indicate that the stresses are relieved at higher temperatures by divacancy flow (silicon self diffusion). The level of residual stress in as-fabricated cells was found to be negligible in the cells tested.
The Water-Induced Linear Reduction Gas Diffusivity Model Extended to Three Pore Regions
DEFF Research Database (Denmark)
Chamindu, T. K. K. Deepagoda; de Jonge, Lis Wollesen; Kawamoto, Ken
2015-01-01
. Characterization of soil functional pore structure is an essential prerequisite to understand key gas transport processes in variably saturated soils in relation to soil ecosystems, climate, and environmental services. In this study, the water-induced linear reduction (WLR) soil gas diffusivity model originally...... gas diffusivity from moist to dry conditions across differently structured porous media, including narrow soil size fractions, perforated plastic blocks, fractured limestone, peaty soils, aggregated volcanic ash soils, and particulate substrates for Earth- or space-based applications. The new Cip...
Induced-Charge Enhancement of the Diffusion Potential in Membranes with Polarizable Nanopores.
Ryzhkov, I I; Lebedev, D V; Solodovnichenko, V S; Shiverskiy, A V; Simunin, M M
2017-12-01
When a charged membrane separates two salt solutions of different concentrations, a potential difference appears due to interfacial Donnan equilibrium and the diffusion junction. Here, we report a new mechanism for the generation of a membrane potential in polarizable conductive membranes via an induced surface charge. It results from an electric field generated by the diffusion of ions with different mobilities. For uncharged membranes, this effect strongly enhances the diffusion potential and makes it highly sensitive to the ion mobilities ratio, electrolyte concentration, and pore size. Theoretical predictions on the basis of the space-charge model extended to polarizable nanopores fully agree with experimental measurements in KCl and NaCl aqueous solutions.
Lei, Youming; Zheng, Fan
2016-12-01
Stochastic chaos induced by diffusion processes, with identical spectral density but different probability density functions (PDFs), is investigated in selected lightly damped Hamiltonian systems. The threshold amplitude of diffusion processes for the onset of chaos is derived by using the stochastic Melnikov method together with a mean-square criterion. Two quasi-Hamiltonian systems, namely, a damped single pendulum and damped Duffing oscillator perturbed by stochastic excitations, are used as illustrative examples. Four different cases of stochastic processes are taking as the driving excitations. It is shown that in such two systems the spectral density of diffusion processes completely determines the threshold amplitude for chaos, regardless of the shape of their PDFs, Gaussian or otherwise. Furthermore, the mean top Lyapunov exponent is employed to verify analytical results. The results obtained by numerical simulations are in accordance with the analytical results. This demonstrates that the stochastic Melnikov method is effective in predicting the onset of chaos in the quasi-Hamiltonian systems.
Pressure-induced anomalous phase transitions and colossal enhancement of piezoelectricity in PbTiO3.
Wu, Zhigang; Cohen, Ronald E
2005-07-15
We find an unexpected tetragonal-to-monoclinic-to-rhombohedral-to-cubic phase transition sequence induced by pressure, and a morphotropic phase boundary in a pure compound using first-principles calculations. Huge dielectric and piezoelectric coupling constants occur in the transition regions, comparable to those observed in the new complex single-crystal solid-solution piezoelectrics such as Pb(Mg(1/3)Nb(2/3))O3-PbTiO3, which are expected to revolutionize electromechanical applications. Our results show that morphotropic phase boundaries and giant piezoelectric effects do not require intrinsic disorder, and open the possibility of studying this effect in simple systems.
Li, Zirun; Mi, Wenbo; Wang, Xiaocha; Zhang, Xixiang
2015-01-01
Anisotropic magnetoresistance (AMR) of the facing-target reactively sputtered epitaxial γ′-Fe4N/CoN bilayers is investigated. The phase shift and rectangular-like AMR appears at low temperatures, which can be ascribed to the interfacial exchange coupling. The phase shift comes from the exchange bias (EB) that makes the magnetization lag behind a small field. When the γ′-Fe4N thickness increases, the rectangular-like AMR appears. The rectangular-like AMR should be from the combined contributions including the EB-induced unidirectional anisotropy, intrinsic AMR of γ′-Fe4N layer and interfacial spin scattering.
Li, Zirun
2015-02-02
Anisotropic magnetoresistance (AMR) of the facing-target reactively sputtered epitaxial γ′-Fe4N/CoN bilayers is investigated. The phase shift and rectangular-like AMR appears at low temperatures, which can be ascribed to the interfacial exchange coupling. The phase shift comes from the exchange bias (EB) that makes the magnetization lag behind a small field. When the γ′-Fe4N thickness increases, the rectangular-like AMR appears. The rectangular-like AMR should be from the combined contributions including the EB-induced unidirectional anisotropy, intrinsic AMR of γ′-Fe4N layer and interfacial spin scattering.
Creep and stress relaxation induced by interface diffusion in metal matrix composites
Li, Yinfeng; Li, Zhonghua
2013-03-01
An analytical solution is developed to predict the creep rate induced by interface diffusion in unidirectional fiber-reinforced and particle reinforced composites. The driving force for the interface diffusion is the normal stress acting on the interface, which is obtained from rigorous Eshelby inclusion theory. The closed-form solution is an explicit function of the applied stress, volume fraction and radius of the fiber, as well as the modulus ratio between the fiber and the matrix. It is interesting that the solution is formally similar to that of Coble creep in polycrystalline materials. For the application of the present solution in the realistic composites, the scale effect is taken into account by finite element analysis based on a unit cell. Based on the solution, a closed-form solution is also given as a description of stress relaxation induced by interfacial diffusion under constant strain. In addition, the analytical solution for the interface stress presented in this study gives some insight into the relationship between the interface diffusion and interface slip. This work was supported by the financial support from the Nature Science Foundation of China (No. 10932007), the National Basic Research Program of China (No. 2010CB631003/5), and the Doctoral Program of Higher Education of China (No. 20100073110006).
Energy Technology Data Exchange (ETDEWEB)
Kim, Tae Gyu; Shin, Eun A [Sanggye Paik Hospital, Inje University College of Medicine, Seoul (Korea, Republic of); Kim, Joung Sook [Mokdong Hospital, Ewha Womans University College of Medicine, Seoul (Korea, Republic of)
2010-12-15
The purpose of this study was to evaluate the high-resolution CT (HRCT) and pathologic findings of mixed herbal medicine-induced diffuse interstitial lung disease. Eight patients (6 women and 2 men, age range: 31 to 81 years, mean age: 51.4 years) who presented with cough or dyspnea after taking mixed herbal medicine were included in this study. All the patients underwent plain chest radiography and HRCT. We obtained pathologic specimens from 7 patients via fluoroscopy guided large bore cutting needle biopsy and transbronchial lung biopsy. All the patients were treated with steroid therapy. The most common HRCT finding was bilateral diffuse ground glass opacity (n=7), followed by peribronchial consolidation (n=5) and inter- or intralobular septal thickening (n=2). For the disease distribution, the lower lung zone was dominantly involved. The pathologic results of 7 patients were nonspecific interstitial pneumonia (n=3), bronchiolitis obliterans organizing pneumonia (n=2), hypersensitivity pneumonitis (n=1) and eosinophilic pneumonia (n=1). Irrespective of the pathologic results, all 8 patients improved clinically and radiologically after steroid treatment. The HRCT findings of mixed herbal medicine-induced diffuse infiltrative lung disease were mainly bilateral diffuse ground glass opacity, peribronchial consolidation and dominant involvement of the lower lung zone. Those pathologic findings were nonspecific and the differential diagnosis could include interstitial pneumonia, bronchiolitis obliterans organizing pneumonia, hypersensitivity pneumonitis and eosinophilic pneumonia
Morphological bubble evolution induced by air diffusion on submerged hydrophobic structures
Lv, Pengyu; Xiang, Yaolei; Xue, Yahui; Lin, Hao; Duan, Huiling
2017-03-01
Bubbles trapped in the cavities always play important roles in the underwater applications of structured hydrophobic surfaces. Air exchange between bubbles and surrounding water has a significant influence on the morphological bubble evolution, which in turn frequently affects the functionalities of the surfaces, such as superhydrophobicity and drag reduction. In this paper, air diffusion induced bubble evolution on submerged hydrophobic micropores under reduced pressures is investigated experimentally and theoretically. The morphological behaviors of collective and single bubbles are observed using confocal microscopy. Four representative evolution phases of bubbles are captured in situ. After depressurization, bubbles will not only grow and coalesce but also shrink and split although the applied pressure remains negative. A diffusion-based model is used to analyze the evolution behavior and the results are consistent with the experimental data. A criterion for bubble growth and shrinkage is also derived along with a phase diagram, revealing that the competition of effective gas partial pressures across the two sides of the diffusion layer dominates the bubble evolution process. Strategies for controlling the bubble evolution behavior are also proposed based on the phase diagram. The current work provides a further understanding of the general behavior of bubble evolution induced by air diffusion and can be employed to better designs of functional microstructured hydrophobic surfaces.
International Nuclear Information System (INIS)
Kim, Tae Gyu; Shin, Eun A; Kim, Joung Sook
2010-01-01
The purpose of this study was to evaluate the high-resolution CT (HRCT) and pathologic findings of mixed herbal medicine-induced diffuse interstitial lung disease. Eight patients (6 women and 2 men, age range: 31 to 81 years, mean age: 51.4 years) who presented with cough or dyspnea after taking mixed herbal medicine were included in this study. All the patients underwent plain chest radiography and HRCT. We obtained pathologic specimens from 7 patients via fluoroscopy guided large bore cutting needle biopsy and transbronchial lung biopsy. All the patients were treated with steroid therapy. The most common HRCT finding was bilateral diffuse ground glass opacity (n=7), followed by peribronchial consolidation (n=5) and inter- or intralobular septal thickening (n=2). For the disease distribution, the lower lung zone was dominantly involved. The pathologic results of 7 patients were nonspecific interstitial pneumonia (n=3), bronchiolitis obliterans organizing pneumonia (n=2), hypersensitivity pneumonitis (n=1) and eosinophilic pneumonia (n=1). Irrespective of the pathologic results, all 8 patients improved clinically and radiologically after steroid treatment. The HRCT findings of mixed herbal medicine-induced diffuse infiltrative lung disease were mainly bilateral diffuse ground glass opacity, peribronchial consolidation and dominant involvement of the lower lung zone. Those pathologic findings were nonspecific and the differential diagnosis could include interstitial pneumonia, bronchiolitis obliterans organizing pneumonia, hypersensitivity pneumonitis and eosinophilic pneumonia
Energy Technology Data Exchange (ETDEWEB)
Khatri, Om P.; Hatanaka, Takeshi; Murase, Kuniaki [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Sugimura, Hiroyuki, E-mail: hiroyuki.sugimura@materials.mbox.media.kyoto-u.ac.jp [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)
2009-09-30
Vacuum ultraviolet (VUV, {lambda} = 172 nm) patterning of alkyl monolayer on silicon surface has been demonstrated with emphasis on the diffusion of VUV induced oxygen-derived active species, which are accountable for the pattern broadening. The VUV photons photo-dissociates the atmospheric oxygen and water molecules into the oxygen-derived active species (oxidants). These oxidants photo-oxidize the hexadecyl (HD) monolayer in VUV irradiated regions (Khatri et al., Langmuir. 24 (2008) 12077), as well as the little concentration of oxidants diffuses towards the masked areas. In this study, we performed VUV patterning at a vacuum pressure of 10 Pa to track the diffusion pathways for the oxidants with help of gold nanoparticles (AuNPs; {phi} = 10 nm) immobilization. At VUV irradiated sites AuNPs are found as uniformly distributed, but adjacent to the pattern boundary we observed quasi-linear arrays of AuNPs, which are determined by diffusion pathways of the oxidants. The diffusion of oxidants plays vital role in pattern broadening. The site selective anchoring of AuNPs demonstrates the utility of VUV photons for the construction of functional materials with microstructural architecture.
Anomalous top magnetic couplings
Indian Academy of Sciences (India)
2012-11-09
Nov 9, 2012 ... Corresponding author. E-mail: remartinezm@unal.edu.co. Abstract. The real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbW vertex in the Standard Model (SM) are computed. Keywords. Top; anomalous. PACS Nos 14.65.Ha; 12.15 ...
The potential role of diffusion-induced grain-boundary migration in extended life prediction
International Nuclear Information System (INIS)
Handwerker, C.A.; Blendell, J.E.; Interrante, C.G.; Ahn, T.M.
1993-01-01
The selection of materials that are suitable for various high-level waste-packaging designs must reflect the need to meet requirements for long-term performance in repository environments that change with time. With this in mind, we examine how grain boundaries in materials are induced to migrate as a result of solute diffusion even at low temperatures, how the composition of the matrix material is changed significantly by this diffusion-induced grain boundary migration (DIGM), and how the changing microstructures and compositions during DIGM lead to major changes in materials performance, such as corrosion or embrittlement. Methods are discussed for prediction of the long-term behavior of materials affected by DIGM
Tunneling Anomalous and Spin Hall Effects.
Matos-Abiague, A; Fabian, J
2015-07-31
We predict, theoretically, the existence of the anomalous Hall effect when a tunneling current flows through a tunnel junction in which only one of the electrodes is magnetic. The interfacial spin-orbit coupling present in the barrier region induces a spin-dependent momentum filtering in the directions perpendicular to the tunneling current, resulting in a skew tunneling even in the absence of impurities. This produces an anomalous Hall conductance and spin Hall currents in the nonmagnetic electrode when a bias voltage is applied across the tunneling heterojunction. If the barrier is composed of a noncentrosymmetric material, the anomalous Hall conductance and spin Hall currents become anisotropic with respect to both the magnetization and crystallographic directions, allowing us to separate this interfacial phenomenon from the bulk anomalous and spin Hall contributions. The proposed effect should be useful for proving and quantifying the interfacial spin-orbit fields in metallic and metal-semiconductor systems.
Energy Technology Data Exchange (ETDEWEB)
Xue, Xu [Electronic Materials; amp,; Dong, Guohua [Electronic Materials; amp,; Zhou, Ziyao [Electronic Materials; amp,; Xian, Dan [Collaborative Innovation Center of High-End Manufacturing; Hu, Zhongqiang [Electronic Materials; amp,; Ren, Wei [Electronic Materials; amp,; Collaborative Innovation Center of High-End Manufacturing; Ye, Zuo-Guang [Electronic Materials; amp,; Department; Chen, Wei [Materials; Jiang, Zhuang-De [Collaborative Innovation Center of High-End Manufacturing; Liu, Ming [Electronic Materials; amp,; Collaborative Innovation Center of High-End Manufacturing
2017-12-01
Controlling spin dynamics through modulation of spin interactions in a fast, compact, and energy-efficient way is compelling for its abundant physical phenomena and great application potential in next-generation voltage controllable spintronic devices. In this work, we report electric field manipulation of spin dynamics-the two-magnon scattering (TMS) effect in Ni0.5Zn0.5Fe2O4 (NZFO)/Pb(Mg2/3Nb1/3)-PbTiO3 (PMN-PT) multiferroic heterostructures, which breaks the bottleneck of magnetostatic interaction-based magnetoelectric (ME) coupling in multiferroics. An alternative approach allowing spin-wave damping to be controlled by external electric field accompanied by a significant enhancement of the ME effect has been demonstrated. A two-way modulation of the TMS effect with a large magnetic anisotropy change up to 688 Oe has been obtained, referring to a 24 times ME effect enhancement at the TMS critical angle at room temperature. Furthermore, the anisotropic spin-freezing behaviors of NZFO were first determined via identifying the spatial magnetic anisotropy fluctuations. A large spin-freezing temperature change of 160 K induced by the external electric field was precisely determined by electron spin resonance.
Xue, Xu; Dong, Guohua; Zhou, Ziyao; Xian, Dan; Hu, Zhongqiang; Ren, Wei; Ye, Zuo-Guang; Chen, Wei; Jiang, Zhuang-De; Liu, Ming
2017-12-13
Controlling spin dynamics through modulation of spin interactions in a fast, compact, and energy-efficient way is compelling for its abundant physical phenomena and great application potential in next-generation voltage controllable spintronic devices. In this work, we report electric field manipulation of spin dynamics-the two-magnon scattering (TMS) effect in Ni 0.5 Zn 0.5 Fe 2 O 4 (NZFO)/Pb(Mg 2/3 Nb 1/3 )-PbTiO 3 (PMN-PT) multiferroic heterostructures, which breaks the bottleneck of magnetostatic interaction-based magnetoelectric (ME) coupling in multiferroics. An alternative approach allowing spin-wave damping to be controlled by external electric field accompanied by a significant enhancement of the ME effect has been demonstrated. A two-way modulation of the TMS effect with a large magnetic anisotropy change up to 688 Oe has been obtained, referring to a 24 times ME effect enhancement at the TMS critical angle at room temperature. Furthermore, the anisotropic spin-freezing behaviors of NZFO were first determined via identifying the spatial magnetic anisotropy fluctuations. A large spin-freezing temperature change of 160 K induced by the external electric field was precisely determined by electron spin resonance.
Kimura, Yuji; Haraguchi, Kazutoshi
2017-05-16
Clay-alcohol-water ternary dispersions were compared with alcohol-water binary mixtures in terms of viscosity and optical absorbance. Aqueous clay dispersions to which lower alcohols (ethanol, 1-propanol, 2-propanol, and tert-butanol) were added exhibited significant viscosity anomalies (maxima) when the alcohol content was 30-55 wt %, as well as optical absorbance anomalies (maxima). The maximum viscosity (η max ) depended strongly on the clay content and varied between 300 and 8000 mPa·s, making it remarkably high compared with the viscosity anomalies (2 mPa·s) observed in alcohol-water binary mixtures. The alcohol content at η max decreased as the hydrophobicity of the alcohol increased. The ternary dispersions with viscosity anomalies exhibited thixotropic behaviors. The effects of other hydrophilic solvents (glycols) and other kinds of clays were also clarified. Based on these findings and the average particle size changes, the viscosity anomalies in the ternary dispersions were explained by alcohol-clustering-induced network formation of the clay nanosheets. It was estimated that 0.9, 1.7, and 2.5 H 2 O molecules per alcohol molecule were required to stabilize the ethanol, 2-propanol, and tert-butanol, respectively, in the clay-alcohol-water dispersions.
Energy Technology Data Exchange (ETDEWEB)
Wee, D.; Parish, G.; Nener, B. [Microelectronics Research Group, The University of Western Australia, 35 Stirling Highway, 6009 Crawley (Perth) (Australia)
2010-10-15
This paper reports on the investigations via 2-D simulation into the accuracy of diffusion length extraction from scanning electron-beam induced current measurements when the diffusion length, L is very short. L is extracted by using the direct method proposed by Chan et al.[1] and later refined by Kurniawan and Ong[2] to take finite junction depth into account. The 2-D simulations were undertaken using Synopsys {sup registered} Sentaurus TCAD and a realistic electron-hole pair generation volume was created using CASINO v2.42[3], a Monte Carlo Scanning Electron Microscope interaction simulation software, and imported into Sentaurus. The voltage and diameter of the electron beam and diffusion length and surface recombination velocity of the semiconductor materials were varied in the simulations to determine the errors in the diffusion length extracted from the EBIC signals as a function of these parameters. The results of the simulation show that the accuracy of the method proposed in[1] is reasonably accurate and that the beam voltage and spot size do not have significant effects on the accuracy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
International Nuclear Information System (INIS)
Wee, D.; Parish, G.; Nener, B.
2010-01-01
This paper reports on the investigations via 2-D simulation into the accuracy of diffusion length extraction from scanning electron-beam induced current measurements when the diffusion length, L is very short. L is extracted by using the direct method proposed by Chan et al.[1] and later refined by Kurniawan and Ong[2] to take finite junction depth into account. The 2-D simulations were undertaken using Synopsys registered Sentaurus TCAD and a realistic electron-hole pair generation volume was created using CASINO v2.42[3], a Monte Carlo Scanning Electron Microscope interaction simulation software, and imported into Sentaurus. The voltage and diameter of the electron beam and diffusion length and surface recombination velocity of the semiconductor materials were varied in the simulations to determine the errors in the diffusion length extracted from the EBIC signals as a function of these parameters. The results of the simulation show that the accuracy of the method proposed in[1] is reasonably accurate and that the beam voltage and spot size do not have significant effects on the accuracy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Atomic diffusion induced degradation in bimetallic layer coated cemented tungsten carbide
International Nuclear Information System (INIS)
Peng, Zirong; Rohwerder, Michael; Choi, Pyuck-Pa; Gault, Baptiste; Meiners, Thorsten; Friedrichs, Marcel; Kreilkamp, Holger; Klocke, Fritz; Raabe, Dierk
2017-01-01
Highlights: • We study the temporal degradation of PtIr/Cr/WC and PtIr/Ni/WC systems. • Short cut diffusion, segregation, oxidation and interdiffusion reactions occurred. • Outward diffusion of Cr (Ni) via PtIr grain boundaries triggered the degradation. • The microstructure of the PtIr layer controlled the systems stability. • We propose an atomic diffusion induced degradation mechanism. - Abstract: We investigated the temporal degradation of glass moulding dies, made of cemented tungsten carbide coated with PtIr on an adhesive Cr or Ni interlayer, by electron microscopy and atom probe tomography. During the exposure treatments at 630 °C under an oxygen partial pressure of 1.12 × 10"−"2"3 bar, Cr (Ni) was found to diffuse outwards via grain boundaries in the PtIr, altering the surface morphology. Upon dissolution of the interlayer, the WC substrate also started degrading. Extensive interdiffusion processes involving PtIr, Cr (Ni) and WC took place, leading to the formation of intermetallic phases and voids, deteriorating the adhesion of the coating.
Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements
International Nuclear Information System (INIS)
Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton
2017-01-01
We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.
International Nuclear Information System (INIS)
Liu Song; Yan Yu-Zhen; Hu Liang-Bin
2012-01-01
The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin—orbit coupling were investigated theoretically. Based on a unified semiclassical theoretical approach, it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin—orbit interactions, namely an intrinsic contribution determined by the Berry curvature in the momentum space, an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin—orbit-dependent impurity scattering. The characteristics of these competing contributions are discussed in detail in the paper. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Energy Technology Data Exchange (ETDEWEB)
Cho, Young Jun; Kim, Joung Sook; Kim, Ji Young; Choi, Soo Jeon [Sanggye Paik Hospital, Inje University College of Medicine, Seoul (Korea, Republic of)
2007-05-15
Propylthiouracil (PTU) is a drug that's used to manage hyperthyroidism and it can, on rare occasions, induce antineutrophil cytoplasmic antibody-associated vasculitis that involved multiple organ systems and it can also cause extremely rare isolated or diffuse pulmonary hemorrhage. We report here on a case of a patient who develop diffuse pulmonary hemorrhage after she had been taking PTU for five years. The patient is a 33-year-old woman who presented with hemoptysis. Simple chest radiographs and the chest CT showed bilateral ground-glass opacity, consolidation and pulmonary arterial hypertension. The bronchoalveolar lavage fluid revealed alveolar hemorrhage. The laboratory values showed increased perinuclear-antineutrophil cytoplasmic antibody ({rho} - ANCA) and anti-peroxidase antibody titers.
Solutions for a non-Markovian diffusion equation
International Nuclear Information System (INIS)
Lenzi, E.K.; Evangelista, L.R.; Lenzi, M.K.; Ribeiro, H.V.; Oliveira, E.C. de
2010-01-01
Solutions for a non-Markovian diffusion equation are investigated. For this equation, we consider a spatial and time dependent diffusion coefficient and the presence of an absorbent term. The solutions exhibit an anomalous behavior which may be related to the solutions of fractional diffusion equations and anomalous diffusion.
A reaction-diffusion model of ROS-induced ROS release in a mitochondrial network.
Directory of Open Access Journals (Sweden)
Lufang Zhou
2010-01-01
Full Text Available Loss of mitochondrial function is a fundamental determinant of cell injury and death. In heart cells under metabolic stress, we have previously described how the abrupt collapse or oscillation of the mitochondrial energy state is synchronized across the mitochondrial network by local interactions dependent upon reactive oxygen species (ROS. Here, we develop a mathematical model of ROS-induced ROS release (RIRR based on reaction-diffusion (RD-RIRR in one- and two-dimensional mitochondrial networks. The nodes of the RD-RIRR network are comprised of models of individual mitochondria that include a mechanism of ROS-dependent oscillation based on the interplay between ROS production, transport, and scavenging; and incorporating the tricarboxylic acid (TCA cycle, oxidative phosphorylation, and Ca(2+ handling. Local mitochondrial interaction is mediated by superoxide (O2.- diffusion and the O2.(--dependent activation of an inner membrane anion channel (IMAC. In a 2D network composed of 500 mitochondria, model simulations reveal DeltaPsi(m depolarization waves similar to those observed when isolated guinea pig cardiomyocytes are subjected to a localized laser-flash or antioxidant depletion. The sensitivity of the propagation rate of the depolarization wave to O(2.- diffusion, production, and scavenging in the reaction-diffusion model is similar to that observed experimentally. In addition, we present novel experimental evidence, obtained in permeabilized cardiomyocytes, confirming that DeltaPsi(m depolarization is mediated specifically by O2.-. The present work demonstrates that the observed emergent macroscopic properties of the mitochondrial network can be reproduced in a reaction-diffusion model of RIRR. Moreover, the findings have uncovered a novel aspect of the synchronization mechanism, which is that clusters of mitochondria that are oscillating can entrain mitochondria that would otherwise display stable dynamics. The work identifies the
Anomalous gauge theories revisited
International Nuclear Information System (INIS)
Matsui, Kosuke; Suzuki, Hiroshi
2005-01-01
A possible formulation of chiral gauge theories with an anomalous fermion content is re-examined in light of the lattice framework based on the Ginsparg-Wilson relation. It is shown that the fermion sector of a wide class of anomalous non-abelian theories cannot consistently be formulated within this lattice framework. In particular, in 4 dimension, all anomalous non-abelian theories are included in this class. Anomalous abelian chiral gauge theories cannot be formulated with compact U(1) link variables, while a non-compact formulation is possible at least for the vacuum sector in the space of lattice gauge fields. Our conclusion is not applied to effective low-energy theories with an anomalous fermion content which are obtained from an underlying anomaly-free theory by sending the mass of some of fermions to infinity. For theories with an anomalous fermion content in which the anomaly is cancelled by the Green-Schwarz mechanism, a possibility of a consistent lattice formulation is not clear. (author)
Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A.; Lee, Jonghwan; Boas, David A.
2018-02-01
Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile, and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of 0.1 to 0.5 × 10-6 mm2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion.
Ito, Yuta; Noda, Kentaro; Aiba, Keisuke; Yano, Shingo; Fujii, Tsunehiro
A 59-year-old female with diffuse large B-cell lymphoma was treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) regimen. In addition, we administered pegfilgrastim for treating chemotherapy-induced febrile neutropenia. She complained of fever and neck and chest pain a few days after pegfilgrastim administration during the third and fourth courses of R-CHOP. Radiological imaging revealed an inflammation of large vessels, which led to the diagnosis of drug-associated vasculitis. We confirmed that vasculitis observed in this case was caused by pegfilgrastim administration because similar symptoms appeared with both injections of pegfilgrastim.
Hopf Bifurcation and Delay-Induced Turing Instability in a Diffusive lac Operon Model
Cao, Xin; Song, Yongli; Zhang, Tonghua
In this paper, we investigate the dynamics of a lac operon model with delayed feedback and diffusion effect. If the system is without delay or the delay is small, the positive equilibrium is stable so that there are no spatial patterns formed; while the time delay is large enough the equilibrium becomes unstable so that rich spatiotemporal dynamics may occur. We have found that time delay can not only incur temporal oscillations but also induce imbalance in space. With different initial values, the system may have different spatial patterns, for instance, spirals with one head, four heads, nine heads, and even microspirals.
Fluctuation relations for anomalous dynamics
International Nuclear Information System (INIS)
Chechkin, A V; Klages, R
2009-01-01
We consider work fluctuation relations (FRs) for generic types of dynamics generating anomalous diffusion: Lévy flights, long-correlated Gaussian processes and time-fractional kinetics. By combining Langevin and kinetic approaches we calculate the probability distributions of mechanical and thermodynamical work in two paradigmatic nonequilibrium situations, respectively: a particle subject to a constant force and a particle in a harmonic potential dragged by a constant force. We check the transient FR for two models exhibiting superdiffusion, where a fluctuation-dissipation relation does not exist, and for two other models displaying subdiffusion, where there is a fluctuation-dissipation relation. In the two former cases the conventional transient FR is not recovered, whereas in the latter two it holds either exactly or in the long-time limit. (letter)
Role Played by Shear-Induced Hydrodynamic Diffusion on the Continuous Separation of Blood Cells
Hoyos, Mauricio; Kurowski, Pascal; Moore, Lee; Williams, Stephen; Zborowski, Maciej
2001-11-01
The continuous sorting of hematopoietic stem cells, lymphocytes or other blood cells can be performed using a membraneless hydrodynamic technique called split-flow thin channel fractionation, SPLITT. Two streams are introduced to the separator: carrier at one inlet and a suspension containing a mixture of immunomagnetically-labeled cells and unlabeled cells at the other inlet. The SPLITT channel, comprising a thin annulus between two concentric cylinders, is fitted into a permanent quadrupole magnet. The sample is transported along the axis of the separation column, and the labeled cells migrate perpendicular to the bulk flow under the influence of the magnetic field. The aim is to recover - at high purity - all of the magnetized cells in the enriched outlet. However, other cells contaminate the enriched fraction. This may be due to a transversal transport of non-immunomagnetically-labeled cells - termed crossover - by shear-induced hydrodynamic diffusion, SIHD, occurring along the separator. The unwanted cell crossover strongly influences the target cell purity in the enriched fraction. We investigate the possible presence of SIHD on the separation of progenitor cells and particles by studying the cross-stream concentration as a function of different parameters: namely, shear rate, inlet concentration and particle size. With our SIHD model we can solve the convection-diffusion equation by assuming an effective diffusion coefficient, which predicts the observed crossover.
Role of spin diffusion in current-induced domain wall motion for disordered ferromagnets
Akosa, Collins Ashu; Kim, Won-Seok; Bisig, André
2015-01-01
Current-induced spin transfer torque and magnetization dynamics in the presence of spin diffusion in disordered magnetic textures is studied theoretically. We demonstrate using tight-binding calculations that weak, spin-conserving impurity scattering dramatically enhances the nonadiabaticity. To further explore this mechanism, a phenomenological drift-diffusion model for incoherent spin transport is investigated. We show that incoherent spin diffusion indeed produces an additional spatially dependent torque of the form ∼∇2[m×(u⋅∇)m]+ξ∇2[(u⋅∇)m], where m is the local magnetization direction, u is the direction of injected current, and ξ is a parameter characterizing the spin dynamics (precession, dephasing, and spin-flip). This torque, which scales as the inverse square of the domain wall width, only weakly enhances the longitudinal velocity of a transverse domain wall but significantly enhances the transverse velocity of vortex walls. The spatial-dependent spin transfer torque uncovered in this study is expected to have significant impact on the current-driven motion of abrupt two-dimensional textures such as vortices, skyrmions, and merons.
Role of spin diffusion in current-induced domain wall motion for disordered ferromagnets
Akosa, Collins Ashu
2015-03-12
Current-induced spin transfer torque and magnetization dynamics in the presence of spin diffusion in disordered magnetic textures is studied theoretically. We demonstrate using tight-binding calculations that weak, spin-conserving impurity scattering dramatically enhances the nonadiabaticity. To further explore this mechanism, a phenomenological drift-diffusion model for incoherent spin transport is investigated. We show that incoherent spin diffusion indeed produces an additional spatially dependent torque of the form ∼∇2[m×(u⋅∇)m]+ξ∇2[(u⋅∇)m], where m is the local magnetization direction, u is the direction of injected current, and ξ is a parameter characterizing the spin dynamics (precession, dephasing, and spin-flip). This torque, which scales as the inverse square of the domain wall width, only weakly enhances the longitudinal velocity of a transverse domain wall but significantly enhances the transverse velocity of vortex walls. The spatial-dependent spin transfer torque uncovered in this study is expected to have significant impact on the current-driven motion of abrupt two-dimensional textures such as vortices, skyrmions, and merons.
Du, Yong; Qiu, Wen-Ze; Lv, Yan; Wu, Jian; Xu, Zhi-Kang
2016-11-02
Nanofiltration membranes (NFMs) are widely used in saline water desalination, wastewater treatment, and chemical product purification. However, conventional NFMs suffer from broad pore size distribution, which limits their applications for fine separation, especially in complete separation of molecules with slight differences in molecular size. Herein, defect-free composite NFMs with narrow pore size distribution are fabricated using a contra-diffusion method, with dopamine/polyethylenimine solution on the skin side and ammonium persulfate solution on the other side of the ultrafiltration substrate. Persulfate ions can diffuse through the ultrafiltration substrate into the other side and in situ trigger dopamine to form a codeposited coating with polyethylenimine. The codeposition is hindered on those sites completely covered by the polydopamine/polyethylenimine coating, although it is promoted at the defects or highly permeable regions because it is induced by the diffused persulfate ions. Such a "self-completion" process results in NFMs with highly uniform structures and narrow pore size distribution, as determined by their rejection of neutral solutes. These near electrically neutral NFMs show a high rejection of divalent ions with a low rejection of monovalent ions (MgCl 2 rejection = 96%, NaCl rejection = 23%), majorly based on a steric hindrance effect. The as-prepared NFMs can be applied in molecular separation such as isolating cellulose hydrogenation products.
Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A; Lee, Jonghwan; Boas, David A
2018-02-01
Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering-optical coherence tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained three-dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of ~0.1 to 0.5 × 10 -6 mm 2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Neoclassical and anomalous transport in axisymmetric toroidal plasmas with electrostatic turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1995-05-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electrostatic fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear term. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. The neoclassical banana-plateau particle and heat fluxes and the bootstrap current are also affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The quasilinear term, the anomalous forces, and the anomalous particle and heat fluxes are evaluated from the fluctuating part of the drift kinetic equation. The averaged drift kinetic equation with the quasilinear term is solved for the plateau regime to derive the parallel viscosities modified by the fluctuations. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. (author)
Energy Technology Data Exchange (ETDEWEB)
Barnard, L., E-mail: lmbarnard@wisc.edu; Morgan, D., E-mail: ddmorgan@wisc.edu
2014-06-01
In this study, ab initio molecular dynamics, implemented via density functional theory, is used to simulate self-interstitial diffusion in pure Ni and in the Ni-18 at.% Cr model alloy. Interstitial tracer diffusivities are measured from simulation results for pure Ni and for both Ni and Cr in the Ni–18Cr alloy. An Arrhenius function fit to these tracer diffusivities is then used in a rate theory model for radiation induced segregation, along with the experimentally measured vacancy diffusivities. It is predicted that interstitial diffusion has a tendency to cause Cr enrichment near grain boundaries, partially counterbalancing the tendency for vacancy diffusion to cause Cr depletion. This results in more mild Cr depletion than would result if only the vacancy diffusion were accounted for, in better agreement with experiment. This physical description of RIS in Ni–Cr alloys, which invokes the effects of both vacancy and interstitial diffusion, is distinct from the conventional description which accounts only for the effect of vacancy diffusion.
International Nuclear Information System (INIS)
Barnard, L.; Morgan, D.
2014-01-01
In this study, ab initio molecular dynamics, implemented via density functional theory, is used to simulate self-interstitial diffusion in pure Ni and in the Ni-18 at.% Cr model alloy. Interstitial tracer diffusivities are measured from simulation results for pure Ni and for both Ni and Cr in the Ni–18Cr alloy. An Arrhenius function fit to these tracer diffusivities is then used in a rate theory model for radiation induced segregation, along with the experimentally measured vacancy diffusivities. It is predicted that interstitial diffusion has a tendency to cause Cr enrichment near grain boundaries, partially counterbalancing the tendency for vacancy diffusion to cause Cr depletion. This results in more mild Cr depletion than would result if only the vacancy diffusion were accounted for, in better agreement with experiment. This physical description of RIS in Ni–Cr alloys, which invokes the effects of both vacancy and interstitial diffusion, is distinct from the conventional description which accounts only for the effect of vacancy diffusion
Using the thermal diffusion cloud chamber to study the ion-induced nucleation by radon decay
International Nuclear Information System (INIS)
Wu, Yefei.
1991-01-01
Thermal diffusion cloud chamber is steady-state device and has been extensively used for nucleation research. In order to study the ion-induced nucleation by radon decay, a new chamber was designed with improved both upper and bottom plates, the system of circulating fluid, the gasketting, the temperature measurement and the insulation. An alternative method of using oxygen as carrier gas was examined. Therefore, the heavy carrier gas including nitrogen, oxygen, neon, argon and air can be used to study radon radiolysis-induced nucleation for the water or organic compounds in the TDCC. The effects of the pressure and temperature ranges on the density, supersaturation, temperature and partial pressure profile for the water-oxygen-helium in the TDCC have been examined. Based on the classical theory, the rate profile of ion-induced nucleation by radon decays was calculated and compared with the homogeneous nucleation. From measured indoor concentrations of Volatile Organic Compounds (VOC), thermodynamic theory models were used to assess the possibility that these compounds will form ultrafine particles in indoor air by ion-induced nucleation. The energy, number of molecules and equilibrium radius of clusters have been calculated based on Such and Thomson theories. These two sets of values have been compared. Ion cluster radii corresponding to 1--3 VOC molecules are in range of 3--5 x 10 -8 cm. 43 refs., 18 figs., 5 tabs
Anomalous water absorption in porous materials
Lockington, D A
2003-01-01
The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuentz and Lavallee (2001) discuss the anomalous b...
International Nuclear Information System (INIS)
Gasparian, A.P.
1984-01-01
Results are presented from a bubble chamber experiment to search for anomalous mean free path (MFP) phenomena for secondary multicharged fragments (Zsub(f)=5 and 6) of the beam carbon nucleus at 4.2 GeV/c per nucleon. A total of 50000 primary interactions of carbon with propane (C 3 H 8 ) were created. Approximately 6000 beam tragments with charges Zsub(f)=5 and 6 were analyzed in detail to find out an anomalous decrease of MFP. The anomaly is observed only for secondary 12 C nuclei
International Nuclear Information System (INIS)
Li, Jia; Fang, Qihong; Wu, Hong; Liu, Youwen; Wen, Pihua
2015-01-01
Highlights: • Diffusion induced stress is established. • Yield stress is dependent upon concentration. • Plastic deformation induced stress lowers tensile stress. • Plastic deformation suppresses crack nucleation. • Plastic deformation occurs not only at lithiated phase but also at electrode interior. - Abstract: This paper is theoretically suggested to describe diffusion induced stress in the elastoplastic hollow spherical silicon electrode for plastic deformation using both analytical model and molecular simulation. Based on the plastic deformation and the yield criterion, we develop this model accounting for the lithium-ion diffusion effect in hollow electrode, focusing on the concentration and stress distributions undergoing lithium-ion insertion. The results show that the two ways, applied compressive stress to inner surface or limited inner surface with higher concentration using biological membranes maintaining concentration difference, lead to the compressive stress induced by the lithium-ion diffusion effect. Hollow spherical electrode reduces effectively diffusion induced stress through controlling and tuning electrode parameters to obtain the reasonably low yield strength. According to MD simulations, plastic deformation phenomenon not only occurs at interface layer of lithiated phase, but also penetrates at electrode interior owning to confinement imposed by lithiated phase. These criteria that radial and hoop stresses reduce dramatically when plastic deformation occurs near the end faces of hollow electrode, may help guide development of new materials for lithium-ion batteries with enhanced mechanical durability, by means of reasonable designing yield strength to maintain mechanical stress below fracture strength, thereby increasing battery life.
International Nuclear Information System (INIS)
Lim, Cheolwoong; Yan Bo; Yin Leilei; Zhu Likun
2012-01-01
Highlights: ► The microstructure of LIB electrodes was obtained by X-ray micro/nano-CT. ► We studied diffusion-induced stresses based on realistic 3D microstructures. ► Stresses depend on geometric characteristics of electrode particle. ► Stresses in a real particle are much higher than those in a spherical particle. - Abstract: Lithium ion batteries experience diffusion-induced stresses during charge and discharge processes which can cause electrode failure in the form of fracture. Previous diffusion-induced stress models and simulations are mainly based on simple active material particle structures, such as spheres and ellipsoids. However, the simple structure model cannot reveal the stress development in a real complex lithium ion battery electrode. In this paper, we studied the diffusion-induced stresses numerically based on a realistic morphology of reconstructed particles during the lithium ion intercalation process. The morphology of negative and positive active materials of a lithium ion battery was determined using X-ray micro/nano computed tomography technology. Diffusion-induced stresses were simulated at different C rates under galvonostatic conditions and compared with spherical particles. The simulation results show that the intercalation stresses of particles depend on their geometric characteristics. The highest von Mises stress and Tresca stress in a real particle are several times higher than the stresses in a spherical particle with the same volume.
Liu, Biao; Wu, Ranchao; Chen, Liping
2018-04-01
Turing instability and pattern formation in a super cross-diffusion predator-prey system with Michaelis-Menten type predator harvesting are investigated. Stability of equilibrium points is first explored with or without super cross-diffusion. It is found that cross-diffusion could induce instability of equilibria. To further derive the conditions of Turing instability, the linear stability analysis is carried out. From theoretical analysis, note that cross-diffusion is the key mechanism for the formation of spatial patterns. By taking cross-diffusion rate as bifurcation parameter, we derive amplitude equations near the Turing bifurcation point for the excited modes by means of weakly nonlinear theory. Dynamical analysis of the amplitude equations interprets the structural transitions and stability of various forms of Turing patterns. Furthermore, the theoretical results are illustrated via numerical simulations. Copyright © 2018. Published by Elsevier Inc.
Pham, Ngot T.; Lee, Seul Lee; Lee, Yong Wook; Kang, Hyun Wook
2017-02-01
Temperature variations are often monitored by using sensors operating at the site of treatment during Laser-induced Interstitial Thermotherapy (LITT). Currently, temperature measurements during LITT have been performed with thermocouples (TCs). However, TCs could directly absorb laser light and lead to self-heating (resulting in an over-estimation). Fiber Bragg grating (FBG) sensors can instead overcome this limitation of the TCs due to its insensitivity to electromagnetic interference. The aim of the current study was to quantitatively evaluate the FBG temperature sensor with a K-type thermocouple to real-time monitor temperature increase in ex vivo tissue during diffuser-assisted LITT. A 4-W 980-nm laser was employed to deliver optical energy in continuous mode through a 600-µm core-diameter diffusing applicator. A goniometric measurement validated the uniform light distribution in polar and longitudinal directions. The FBG sensor showed a linear relationship (R2 = 0.995) between wavelength shift and temperature change in air and tissue along with a sensitivity of 0.0114 nm/˚C. Regardless of sensor type, the measured temperature increased with irradiation time and applied power but decreased with increasing distance from the diffuser surface. The temperature elevation augmented the degree of thermal coagulation in the tissue during LITT (4.0±0.3-mm at 99˚C after 120-s). The temperature elevation augmented the degree of thermal coagulation in the tissue during LITT s irradiation). The FBG-integrated diffuser was able to monitor the interstitial temperature in tubular tissue (porcine urethra) real-time during laser treatment. However, the thermal coagulation thickness of the porcine urethra was measured to be 1.5 mm that was slightly thicker ( 20%) than that of the bovine liver after 4-W 980-nm laser for 48 s. The FBG temperature sensor can be a feasible tool to real-time monitor the temporal development of the temperature during the diffuser-assisted LITT to
Diffusion tensor imaging detects ventilation-induced brain injury in preterm lambs.
Directory of Open Access Journals (Sweden)
Dhafer M Alahmari
Full Text Available Injurious mechanical ventilation causes white matter (WM injury in preterm infants through inflammatory and haemodynamic pathways. The relative contribution of each of these pathways is not known. We hypothesised that in vivo magnetic resonance imaging (MRI can detect WM brain injury resulting from mechanical ventilation 24 h after preterm delivery. Further we hypothesised that the combination of inflammatory and haemodynamic pathways, induced by umbilical cord occlusion (UCO increases brain injury at 24 h.Fetuses at 124±2 days gestation were exposed, instrumented and either ventilated for 15 min using a high tidal-volume (VT injurious strategy with the umbilical cord intact (INJ; inflammatory pathway only, or occluded (INJ+UCO; inflammatory and haemodynamic pathway. The ventilation groups were compared to lambs that underwent surgery but were not ventilated (Sham, and lambs that did not undergo surgery (unoperated control; Cont. Fetuses were placed back in utero after the 15 min intervention and ewes recovered. Twenty-four hours later, lambs were delivered, placed on a protective ventilation strategy, and underwent MRI of the brain using structural, diffusion tensor imaging (DTI and magnetic resonance spectroscopy (MRS techniques.Absolute MRS concentrations of creatine and choline were significantly decreased in INJ+UCO compared to Cont lambs (P = 0.03, P = 0.009, respectively; no significant differences were detected between the INJ or Sham groups and the Cont group. Axial diffusivities in the internal capsule and frontal WM were lower in INJ and INJ+UCO compared to Cont lambs (P = 0.05, P = 0.04, respectively. Lambs in the INJ and INJ+UCO groups had lower mean diffusivities in the frontal WM compared to Cont group (P = 0.04. DTI colour mapping revealed lower diffusivity in specific WM regions in the Sham, INJ, and INJ+UCO groups compared to the Cont group, but the differences did not reach significance. INJ+UCO lambs more likely to exhibit
DEFF Research Database (Denmark)
Liu, S.J.; Tao, H.Z.; Zhang, Y.F.
2015-01-01
We investigate the sodium inward diffusion (i.e., sodium diffusion from surface toward interior) in iron containing alkaline earth silicate glasses under reducing conditions around Tg and the induced surface crystallization. The surface crystallization is caused by formation of a silicate-gel lay......+ ions have stronger bonds to oxygen and lower coordination number (4~5) than Ca2+, Sr2+ and Ba2+ ions. In contrast, a cristobalite layer forms in Ca-, Sr- and Ba-containing glasses....
Czech Academy of Sciences Publication Activity Database
Nagaosa, N.; Sinova, Jairo; Onoda, S.; MacDonald, A. H.; Ong, N. P.
2010-01-01
Roč. 82, č. 2 (2010), s. 1539-1592 ISSN 0034-6861 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 51.695, year: 2010
Anomalous vacuum expectation values
International Nuclear Information System (INIS)
Suzuki, H.
1986-01-01
The anomalous vacuum expectation value is defined as the expectation value of a quantity that vanishes by means of the field equations. Although this value is expected to vanish in quantum systems, regularization in general produces a finite value of this quantity. Calculation of this anomalous vacuum expectation value can be carried out in the general framework of field theory. The result is derived by subtraction of divergences and by zeta-function regularization. Various anomalies are included in these anomalous vacuum expectation values. This method is useful for deriving not only the conformal, chiral, and gravitational anomalies but also the supercurrent anomaly. The supercurrent anomaly is obtained in the case of N = 1 supersymmetric Yang-Mills theory in four, six, and ten dimensions. The original form of the energy-momentum tensor and the supercurrent have anomalies in their conservation laws. But the modification of these quantities to be equivalent to the original one on-shell causes no anomaly in their conservation laws and gives rise to anomalous traces
Temperature dependent anomalous statistics
International Nuclear Information System (INIS)
Das, A.; Panda, S.
1991-07-01
We show that the anomalous statistics which arises in 2 + 1 dimensional Chern-Simons gauge theories can become temperature dependent in the most natural way. We analyze and show that a statistic's changing phase transition can happen in these theories only as T → ∞. (author). 14 refs
Anomalous superconductivity in black phosphorus under high pressures
International Nuclear Information System (INIS)
Kawamura, H.; Tachikawa, K.
1984-01-01
Pressure induced superconductivity in single crystals of black phosphorus has been studied. Maximum onset Tsub(c) was near 13 K. The anomalous superconductivity may be explained in terms of excitonic mechanism. (author)
Energy Technology Data Exchange (ETDEWEB)
Offiah, C. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom); Hall, E. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom)], E-mail: curtis.offiah@bartsandthelondon.nhs.uk
2008-02-15
Aim: To describe the magnetic resonance imaging (MRI) characteristics of heroin-induced leukoencephalopathy or 'chasing the dragon syndrome' and, in particular, the diffusion-weighted imaging (DWI) and MR spectroscopy (MRS) features. Material and methods: Six patients with a clinical or histopathological diagnosis of heroin-induced leukoencephalopathy were identified and MRI examinations, including DWI and single-voxel MRS, reviewed. Results: Cerebellar white matter was involved in all six cases demonstrating similar symmetrical distribution with sparing of the dentate nuclei. Brain stem signal change was evident in five of the six patients imaged. Supratentorial brain parenchymal involvement, as well as brain stem involvement, correlated anatomically with corticospinal tract distribution. None of the areas of signal abnormality were restricted on DWI. Of those patients subjected to MRS, the areas of parenchymal damage demonstrated reduced N-acetylaspartate, reduced choline, and elevated lactate. Conclusion: Heroin-induced leukoencephalopathy results in characteristic and highly specific signal abnormalities on MRI, which can greatly aid diagnosis. DWI and MRS findings can be explained by known reported neuropathological descriptions in this condition and can be used to support a proposed mechanism for the benefit of current recommended drug treatment regimes.
Diffusion-induced grain boundary migration during ion beam mixing of Au/Cu bilayers
International Nuclear Information System (INIS)
Alexander, D.E.; Baldo, P.M.; Rehn, L.E.
1992-09-01
Experiments were performed to evaluate the effect of 1.5 MeV Kr irradiation on diffusion-induced grain boundary migration (DIGM) in Au/Cu bilayers in the temperature range of 300≤T≤050K. The experimental results were consistent with DIGM occurring in bilayers both during irradiation and during annealing treatments. Rutherford backscattering spectrometry showed a nearly uniform distribution of Cu present through the entire thickness of appropriately prepared polycrystalline Au films irradiated or annealed at temperatures ≥400K. No parallel effect was seen in similarly treated single-crystal films. In each polycrystalline sample studied, irradiation resulted in greater amounts of Cu present uniformly in the Au compared to annealing-only. The magnitudes of measured Cu compositions were substantially greater than that expected solely from grain boundary diffusion. A simple analysis of the process indicated that ion irradiation affects DIGM by increasing the composition of Cu present in alloyed zones and/or by increasing the grain boundary velocity in the Au
Siozos, Panagiotis; Philippidis, Aggelos; Anglos, Demetrios
2017-11-01
A novel, portable spectrometer, combining two analytical techniques, laser-induced breakdown spectroscopy (LIBS) and diffuse reflectance spectroscopy, was developed with the aim to provide an enhanced instrumental and methodological approach with regard to the analysis of pigments in objects of cultural heritage. Technical details about the hybrid spectrometer and its operation are presented and examples are given relevant to the analysis of paint materials. Both LIBS and diffuse reflectance spectra in the visible and part of the near infrared, corresponding to several neat mineral pigment samples, were recorded and the complementary information was used to effectively distinguish different types of pigments even if they had similar colour or elemental composition. The spectrometer was also employed in the analysis of different paints on the surface of an ancient pottery sherd demonstrating the capabilities of the proposed hybrid diagnostic approach. Despite its instrumental simplicity and compact size, the spectrometer is capable of supporting analytical campaigns relevant to archaeological, historical or art historical investigations, particularly when quick data acquisition is required in the context of surveys of large numbers of objects and samples.
Energy Technology Data Exchange (ETDEWEB)
Rolly, Gaboriaud, E-mail: Rolly.gaboriaud@univ-poitiers.fr [Institut Pprime, CNRS-University of Poitiers, SP2MI-BP 30179, 86962 Chasseneuil-Futuroscope (France); Fabien, Paumier [Institut Pprime, CNRS-University of Poitiers, SP2MI-BP 30179, 86962 Chasseneuil-Futuroscope (France); Bertrand, Lacroix [CSIC – University of Sevilla, Avenida Américo Vespucio, 49, 41092 Sevilla (Spain)
2014-05-01
Ion-irradiation induced diffusion and the phase transformation of a bixbyite-fluorite related rare earth oxide thin films are studied. This work is focused on yttrium sesquioxide, Y{sub 2}O{sub 3}, thin films deposited on Si (1 0 0) substrates using the ion beam sputtering technique (IBS). As-deposited samples were annealed ant then irradiated at cryogenic temperature (80 K) with 260 keV Xe{sup 2+} at different fluences. The irradiated thin oxide films are characterized by X-ray diffraction. A cubic to monoclinic phase transformation was observed. Analysis of this phenomenon is done in terms of residual stresses. Stress measurements as a function of irradiation fluences were realised using the XRD-sin{sup 2}ψ method. Stress evolution and kinetic of the phase transformation are compared and leads to the role-played by the nucleation of point and extended defects.
INFLUENCE OF THERMOHALINE CONVECTION ON DIFFUSION-INDUCED IRON ACCUMULATION IN A STARS
International Nuclear Information System (INIS)
Theado, S.; Vauclair, S.; Alecian, G.; LeBlanc, F.
2009-01-01
Atomic diffusion may lead to heavy-element accumulation inside stars in certain specific layers. Iron accumulation in the Z-bump opacity region has been invoked by several authors to quantitatively account for abundance anomalies observed in some stars, or to account for stellar oscillations through the induced κ-mechanism. These authors, however, never took into account the fact that such an accumulation creates an inverse μ-gradient, unstable for thermohaline convection. Here, we present results for A-F stars, where abundance variations are computed with and without this process. We show that iron accumulation is still present when thermohaline convection is taken into account, but much reduced compared to when this physical process is neglected. The consequences of thermohaline convection for A-type stars as well as for other types of stars are presented.
DEFF Research Database (Denmark)
Mahmood, Faisal; Hansen, Rasmus H; Agerholm-Larsen, Birgit
2015-01-01
BACKGROUND: Tissue permeabilization by electroporation (EP) is a promising technique to treat certain cancers. Non-invasive methods for verification of induced permeabilization are important, especially in deep-seated cancers. In this study we evaluated diffusion-weighted magnetic resonance imaging...... (NP), transient membrane permeabilization (TMP), and permanent membrane permeabilization (PMP), respectively. DW-MRI was acquired 5 minutes, 2 hours, 24 hours and 48 hours after EP. Histology was performed for validation of the permeabilization states. Tissue content of water, Na+, K+, Ca2...... minutes after EP, compared to NP. Kurtosis was also significantly higher at 24 hours (pstates, supporting the DW-MRI findings. We conclude that DW-MRI is capable of detecting EP...
Anomalous transport in tokamaks
International Nuclear Information System (INIS)
Wootton, A.J.
1989-01-01
A review is presented of what is known about anomalous transport in tokamaks. It is generally thought that this anomalous transport is the result of fluctuations in various plasma parameters. In the plasma edge detailed measurements of the quantities required to directly determine the fluctuation driven fluxes are available. The total flux of particles is well explained by the measured electrostatic fluctuation driven flux. However, a satisfactory model to explain the origin of the fluctuations has not been identified. The processes responsible for determining the edge energy flux are less clear, but electrostatic convection plays an important part. In the confinement region experimental observations are presently restricted to measurements of density and potential fluctuations and their correlations. The characteristics of the measured fluctuations are discussed and compared with the predictions of various models. Comparisons between measured particle, electron heat and ion heat fluxes, and those fluxes predicted to result from the measured fluctuations, are made. Magnetic fluctuations is discussed
International Nuclear Information System (INIS)
Karmanov, V.A.
1983-01-01
Experimental data are given, the status of anomalon problem is discussed, theoretical approaches to this problem are outlined. Anomalons are exotic objects formed following fragmentation of nuclei-targets under the effect of nuclei - a beam at the energy of several GeV/nucleon. These nuclear fragments have an anomalously large cross section of interaction and respectively, small free path, considerably shorter than primary nuclei have. The experimental daa are obtained in accelerators following irradiation of nuclear emulsions by 16 O, 56 Fe, 40 Ar beams, as well as propane by 12 C beams. The experimental data testify to dependence of fragment free path on the distance L from the point of the fragment formation. A decrease in the fragment free path is established more reliably than its dependence on L. The problem of the anomalon existence cannot be yet considered resolved. Theoretical models suggested for explanation of anomalously large cross sections of nuclear fragment interaction are variable and rather speculative
International Nuclear Information System (INIS)
Nagesh, Vijaya; Tsien, Christina I.; Chenevert, Thomas L.; Ross, Brian D.; Lawrence, Theodore S.; Junick, Larry; Cao Yue
2008-01-01
Purpose: To quantify the radiation-induced changes in normal-appearing white matter before, during, and after radiotherapy (RT) in cerebral tumor patients. Methods and Materials: Twenty-five patients with low-grade glioma, high-grade glioma, or benign tumor treated with RT were studied using diffusion tensor magnetic resonance imaging. The biologically corrected doses ranged from 50 to 81 Gy. The temporal changes were assessed before, during, and to 45 weeks after the start of RT. The mean diffusivity of water ( ), fractional anisotropy of diffusion, diffusivity perpendicular (λ perpendicular ) and parallel (λ parallel ) to white matter fibers were calculated in normal-appearing genu and splenium of the corpus callosum. Results: In the genu and splenium, fractional anisotropy decreased and , λ parallel , λ -perpendicular increased linearly and significantly with time (p -perpendicular had increased ∼30% in the genu and splenium, and λ parallel had increased 5% in the genu and 9% in the splenium, suggesting that demyelination is predominant. The increases in λ perpendicular and λ parallel were dose dependent, starting at 3 weeks and continuing to 32 weeks from the start of RT. The dose-dependent increase in λ perpendicular and λ parallel was not sustained after 32 weeks, indicating the transition from focal to diffuse effects. Conclusion: The acute and subacute changes in normal-appearing white matter fibers indicate radiation-induced demyelination and mild structural degradation of axonal fibers. The structural changes after RT are progressive, with early dose-dependent demyelination and subsequent diffuse dose-independent demyelination and mild axonal degradation. Diffusion tensor magnetic resonance imaging is potentially a biomarker for the assessment of radiation-induced white matter injury
Wang, Silun; Wu, Ed X; Qiu, Deqiang; Leung, Lucullus H T; Lau, Ho-Fai; Khong, Pek-Lan
2009-02-01
Radiation-induced white matter (WM) damage is a major side effect of whole brain irradiation among childhood cancer survivors. We evaluate longitudinally the diffusion characteristics of the late radiation-induced WM damage in a rat model after 25 and 30 Gy irradiation to the hemibrain at 8 time points from 2 to 48 weeks postradiation. We hypothesize that diffusion tensor magnetic resonance imaging (DTI) indices including fractional anisotropy (FA), trace, axial diffusivity (lambda(//)), and radial diffusivity (lambda( perpendicular)) can accurately detect and monitor the histopathologic changes of radiation-induced WM damage, measured at the EC, and that these changes are dose and time dependent. Results showed a progressive reduction of FA, which was driven by reduction in lambda(//) from 4 to 40 weeks postradiation, and an increase in lambda( perpendicular) with return to baseline in lambda(//) at 48 weeks postradiation. Histologic evaluation of irradiated WM showed reactive astrogliosis from 4 weeks postradiation with reversal at 36 weeks, and demyelination, axonal degeneration, and necrosis at 48 weeks postradiation. Moreover, changes in lambda(//) correlated with reactive astrogliosis (P histopathologic changes of WM damage and our results support the use of DTI as a biomarker to noninvasively monitor radiation-induced WM damage.
Yang, Bin; Ming, Wenmei; Du, Mao-Hua; Keum, Jong K; Puretzky, Alexander A; Rouleau, Christopher M; Huang, Jinsong; Geohegan, David B; Wang, Xiaoping; Xiao, Kai
2018-05-01
A fundamental understanding of the interplay between the microscopic structure and macroscopic optoelectronic properties of organic-inorganic hybrid perovskite materials is essential to design new materials and improve device performance. However, how exactly the organic cations affect the structural phase transition and optoelectronic properties of the materials is not well understood. Here, real-time, in situ temperature-dependent neutron/X-ray diffraction and photoluminescence (PL) measurements reveal a transformation of the organic cation CH 3 NH 3 + from order to disorder with increasing temperature in CH 3 NH 3 PbBr 3 perovskites. The molecular-level order-to-disorder transformation of CH 3 NH 3 + not only leads to an anomalous increase in PL intensity, but also results in a multidomain to single-domain structural transition. This discovery establishes the important role that organic cation ordering has in dictating structural order and anomalous optoelectronic phenomenon in hybrid perovskites. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Theory of spin-lattice relaxation of diffusing light nuclei in glasses
International Nuclear Information System (INIS)
Schirmer, A.; Schirmacher, W.
1988-01-01
NMR data of diffusion-induced spin-lattice relaxation in glasses cannot generally be interpreted in the framework of the classical theory of Bloembergen, Purcell and Pound (BPP). Since it is based on exponential density relaxation, generally bnot found in glasses, the BPP formula must be generalized. Here a combination of standard relaxation theory with a hopping model for diffusion in glasses is present. It is shown that the observed anomaties in the NMR data can be explained as a result of anomalous diffusion. 25 refs.; 1 figure
Anomalous momentum transport from drift waves
International Nuclear Information System (INIS)
Dominguez, R.R.; Staebler, G.M.
1993-01-01
A sheared slab magnetic field model B = B 0 [z + (x/L s )y], with inhomogeneous flows in the y and z directions, is used to perform a fully-kinetic stability analysis of the ion temperature gradient (ITG) and dissipative trapped electron (DTE) modes. The concomitant quasilinear stress components that couple to the local perpendicular (y-component) and parallel (z-component) momentum transport are also calculated and the anomalous perpendicular and parallel viscous stresses obtained. A breakdown of the ITG-induced perpendicular viscous stress is generally observed at moderate values of the sheared perpendicular flow. The ITG-induced parallel viscous stress is generally larger and strongly dependent on the sheared flows. The DTE-induced perpendicular viscous stress may sometimes be negative, tending to cancel the ITG contributions while the DTE-induced parallel viscous stress is generally small. The effect of the perpendicular stress component in the momentum balance equations is generally small while the parallel stress component can dominate the usual neoclassical viscous stress terms. The dominant contribution to parallel viscous stress by the ITG mode suggests that bulk plasma toroidal momentum confinement, like energy confinement, is governed by an anomalous ion loss mechanism. Furthermore, the large anomalous effect suggests that the neoclassical explanation of poloidal flows in tokamaks may be incorrect. The present results are in general agreement with existing experimental observations on momentum transport in tokamaks
Diffusion in reactor materials
International Nuclear Information System (INIS)
Fedorov, G.B.; Smirnov, E.A.
1984-01-01
The monograph contains a brief description of the principles underlying the theory of diffusion, as well as modern methods of studying diffusion. Data on self-diffusion and diffusion of impurities in a nuclear fuel and fissionable materials (uranium, plutonium, thorium, zirconium, titanium, hafnium, niobium, molybdenum, tungsten, beryllium, etc.) is presented. Anomalous diffusion, diffusion of components, and interdiffusion in binary and ternary alloys were examined. The monograph presents the most recent reference material on diffusion. It is intended for a wide range of researchers working in the field of diffusion in metals and alloys and attempting to discover new materials for application in nuclear engineering. It will also be useful for teachers, research scholars and students of physical metallurgy
Theory of anomalous transport in toroidal helical plasmas
International Nuclear Information System (INIS)
Itoh, K.; Itoh, S.; Fukuyama, A.
1992-03-01
Theoretical model of the anomalous transport in Torsatron/Heliotron plasmas is developed, based on the current-diffusive interchange instability which is destabilized due to the averaged magnetic hill near edge. Analytic formula of transport coefficient is derived. This model explains the high edge transport, the power degradation and energy confinement scaling law and the enhanced heat-pulse thermal conduction. (author)
International Nuclear Information System (INIS)
Steinbach, E.
1987-01-01
The cellular model of a dislocation is used for an investigation of the time-dependent diffusion process of irradiation-induced point defects interacting with the stress field of a moving dislocation. An analytic solution is given taking into account the elastic interaction due to the first-order size effect and the stress-induced interaction, the kinematic interaction due to the dislocation motion as well as the presence of secondary neutral sinks. The results for the space and time-dependent point defect concentration, represented in terms of Mathieu-Bessel and Mathieu-Hankel functions, emphasize the influence of the parameters which have been taken into consideration. Proceeding from these solutions, formulae for the diffusion flux reaching unit length of the dislocation, which plays an important role with regard to void swelling and irradiation-induced creep, are derived
International Nuclear Information System (INIS)
Lu Yi; Qian Haixin
2003-01-01
To observe whether ionizing radiation could induce up - regulation of Fas receptor expression and apoptosis in diffuse type stomach carcinoma. To investigate the relationship among ionizing radiation, apoptosis and the expression of Fas in stomach carcinoma. Methods: Firstly, the experimental model of SGC - 7901 cell lines was set up and diffuse type stomach carcinoma orthotopically implanted in nude mice. Then 21 model mice were randomized into three groups equally i.e., the control group ( group A ) and two irradiation groups ( group B and group C, executed at 24 hours and 48 hours after irradiation respectively ). The mice in group B and group C were irradiated with 6 MV X-rays at a dose of 20 Gy. By using the methods of TUNEL and immunohistochemical staining, the changes of apoptosis index and Fas expression in tumor tissues were examined. Results: (1) The spontaneous apoptosis index (AI) of tumor tissues was significantly lower than that of mucosa tissues (P 0.05). (3) The Fas LI of tumor tissues increased after irradiation compared with the control group (P<0.05). (4) The changes of AI and Fas LI in all groups with similar tendency showed positive correlation (P<0.01). Conclusion: The apoptosis of diffuse type stomach carcinoma is seriously restrained. Ionizing radiation can induce apoptosis and up - regulate the expression of Fas in diffuse type stomach carcinoma. The apoptosis induced by irradiation maybe depend on the up - regulating of Fas after irradiation
International Nuclear Information System (INIS)
Sykora, D.W.; Yule, D.E.
1996-04-01
This report documents a reassessment of liquefaction potential and estimation of earthquake-induced settlements for the U.S. Department of Energy (DOE), Paducah Gaseous Diffusion Plant (PGDP), located southwest of Paducah, KY. The U.S. Army Engineer Waterways Experiment Station (WES) was authorized to conduct this study from FY91 to FY94 by the DOE, Oak Ridge Operations (ORO), Oak Ridge, TN, through Inter- Agency Agreement (IAG) No. DE-AI05-91OR21971. The study was conducted under the Gaseous Diffusion Plant Safety Analysis Report (GDP SAR) Program
Directory of Open Access Journals (Sweden)
Juerg Schliessbach
2012-01-01
Full Text Available Diffuse noxious inhibitory control (DNIC is described as one possible mechanism of acupuncture analgesia. This study investigated the analgesic effect of acupuncture without stimulation compared to nonpenetrating sham acupuncture (NPSA and cold-pressor-induced DNIC. Forty-five subjects received each of the three interventions in a randomized order. The analgesic effect was measured using pressure algometry at the second toe before and after each of the interventions. Pressure pain detection threshold (PPDT rose from 299 kPa (SD 112 kPa to 364 kPa (SD 144, 353 kPa (SD 135, and 467 kPa (SD 168 after acupuncture, NPSA, and DNIC test, respectively. There was no statistically significant difference between acupuncture and NPSA at any time, but a significantly higher increase of PPDT in the DNIC test compared to acupuncture and NPSA. PPDT decreased after the DNIC test, whereas it remained stable after acupuncture and NPSA. Acupuncture needling at low pain stimulus intensity showed a small analgesic effect which did not significantly differ from placebo response and was significantly less than a DNIC-like effect of a painful noninvasive stimulus.
A reaction-diffusion model for radiation-induced bystander effects.
Olobatuyi, Oluwole; de Vries, Gerda; Hillen, Thomas
2017-08-01
We develop and analyze a reaction-diffusion model to investigate the dynamics of the lifespan of a bystander signal emitted when cells are exposed to radiation. Experimental studies by Mothersill and Seymour 1997, using malignant epithelial cell lines, found that an emitted bystander signal can still cause bystander effects in cells even 60 h after its emission. Several other experiments have also shown that the signal can persist for months and even years. Also, bystander effects have been hypothesized as one of the factors responsible for the phenomenon of low-dose hyper-radiosensitivity and increased radioresistance (HRS/IRR). Here, we confirm this hypothesis with a mathematical model, which we fit to Joiner's data on HRS/IRR in a T98G glioma cell line. Furthermore, we use phase plane analysis to understand the full dynamics of the signal's lifespan. We find that both single and multiple radiation exposure can lead to bystander signals that either persist temporarily or permanently. We also found that, in an heterogeneous environment, the size of the domain exposed to radiation and the number of radiation exposures can determine whether a signal will persist temporarily or permanently. Finally, we use sensitivity analysis to identify those cell parameters that affect the signal's lifespan and the signal-induced cell death the most.
Diffusion induced nuclear reactions in metals: a possible source of heat in the core
International Nuclear Information System (INIS)
Hamza, V.M.; Iyer, S.S.S.
1989-01-01
It has recently been proposed that diffusion of light nuclei in metals can give rise to unusual electrical charge distributions in their lattice structures, inducing thereby certain nuclear reactions that are otherwise uncommon. In the light of these results we advance the hypothesis that such nuclear reactions take place in the metal rich core of the earth, based on following observations: 1 - The solubility of hydrogen in metals is relatively high compared to that in silicates. 2 - Studies of rare gas samples in intraplate volcanos and diamonds show that 3 He/ He ratio increases with depth in the mantle. 3 - There are indications that He is positively correlated with enrichment of metals in lavas. We propose that hydrogen incorporated into metallic phases at the time of planetary accretion was carried to the core by downward migration of metal rich melts during the early states of proto-earth. Preliminary estimates suggest that cold fusion reactions can give rise to an average rate of heat generation of 8.2x10 12 W and may thus serve as a supplementary source of energy for the geomagnetic dynamo. (author)
Energy Technology Data Exchange (ETDEWEB)
Lawrenz, M.
2007-10-30
In the present work the dynamics of CO-molecules on a stepped Pt(111)-surface induced by fs-laser pulses at low temperatures was studied by using laser spectroscopy. In the first part of the work, the laser-induced diffusion for the CO/Pt(111)-system could be demonstrated and modelled successfully for step diffusion. At first, the diffusion of CO-molecules from the step sites to the terrace sites on the surface was traced. The experimentally discovered energy transfer time of 500 fs for this process confirms the assumption of an electronically induced process. In the following it was explained how the experimental results were modelled. A friction coefficient which depends on the electron temperature yields a consistent model, whereas for the understanding of the fluence dependence and time-resolved measurements parallel the same set of parameters was used. Furthermore, the analysis was extended to the CO-terrace diffusion. Small coverages of CO were adsorbed to the terraces and the diffusion was detected as the temporal evolution of the occupation of the step sites acting as traps for the diffusing molecules. The additional performed two-pulse correlation measurements also indicate an electronically induced process. At the substrate temperature of 40 K the cross-correlation - where an energy transfer time of 1.8 ps was extracted - suggests also an electronically induced energy transfer mechanism. Diffusion experiments were performed for different substrate temperatures. (orig.)
Pattern formation induced by cross-diffusion in a predator–prey system
International Nuclear Information System (INIS)
Sun Guiquan; Jin Zhen; Liu Quanxing; Li Li
2008-01-01
This paper considers the Holling–Tanner model for predator–prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients. However, combined with cross-diffusion, it shows that the system will exhibit spotted pattern by both mathematical analysis and numerical simulations. Furthermore, asynchrony of the predator and the prey in the space. The obtained results show that cross-diffusion plays an important role on the pattern formation of the predator–prey system. (general)
Fickian dispersion is anomalous
Cushman, John H.; O'Malley, Dan
2015-12-01
The thesis put forward here is that the occurrence of Fickian dispersion in geophysical settings is a rare event and consequently should be labeled as anomalous. What people classically call anomalous is really the norm. In a Lagrangian setting, a process with mean square displacement which is proportional to time is generally labeled as Fickian dispersion. With a number of counter examples we show why this definition is fraught with difficulty. In a related discussion, we show an infinite second moment does not necessarily imply the process is super dispersive. By employing a rigorous mathematical definition of Fickian dispersion we illustrate why it is so hard to find a Fickian process. We go on to employ a number of renormalization group approaches to classify non-Fickian dispersive behavior. Scaling laws for the probability density function for a dispersive process, the distribution for the first passage times, the mean first passage time, and the finite-size Lyapunov exponent are presented for fixed points of both deterministic and stochastic renormalization group operators. The fixed points of the renormalization group operators are p-self-similar processes. A generalized renormalization group operator is introduced whose fixed points form a set of generalized self-similar processes. Power-law clocks are introduced to examine multi-scaling behavior. Several examples of these ideas are presented and discussed.
Anomalous photoconductivity of ferrocene
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, A K [Indian Association for the Cultivation of Science, Calcutta (India). Dept. of Spectroscopy; Mallik, B [Indian Association for the Cultivation of Science, Calcutta (India). Dept. of Spectroscopy
1995-08-15
Photoconductivity behaviour of ferrocene, a very useful metallo-organic sandwich compound, has been investigated at different constant temperatures using powdery material in a sandwich type of cell configuration and with the exposure of a polychromatic light source (mercury lamp of 125 W). Measurements with a constant d.c. bias voltage (27 V) across the sample cell and a fixed intensity of the exciting light source have shown a drastic change in the photocurrent versus time profile with the increase in temperature. Anomalous changes have been observed in the plot of the photocurrent versus reciprocal of temperature. Such changes are completely absent in the corresponding dark current behaviour. The photoinduced changes have been observed to be almost reversible in the entire temperature range. In a particular temperature range the reversibility of photocurrent is accompanied by fluctuations in equilibrium current obtained after switching off the light source. The observed anomalous changes in photocurrent have been explained by photoinduced phase transition in ferrocene. The possible origin and implications of this photoinduced phase transition are discussed. (orig.)
Anomalous Dimensions of Conformal Baryons
DEFF Research Database (Denmark)
Pica, Claudio; Sannino, Francesco
2016-01-01
We determine the anomalous dimensions of baryon operators for the three color theory as function of the number of massless flavours within the conformal window to the maximum known order in perturbation theory. We show that the anomalous dimension of the baryon is controllably small, within...
Charge-induced secondary atomization in diffusion flames of electrostatic sprays
Gomez, Alessandro; Chen, Gung
1994-01-01
The combustion of electrostatic sprays of heptane in laminar counterflow diffusion flames was experimentally studied by measuring droplet size and velocity distributions, as well as the gas-phase temperature. A detailed examination of the evolution of droplet size distribution as droplets approach the flame shows that, if substantial evaporation occurs before droplets interact with the flame, an initially monodisperse size distribution becomes bimodal. A secondary sharp peak in the size histogram develops in correspondence of diameters about one order of magnitude smaller than the mean. No evaporation mechanism can account for the development of such bimodality, that can be explained only in terms of a disintegration of droplets into finer fragments of size much smaller than that of the parent. Other evidence in support of this interpretation is offered by the measurements of droplet size-velocity correlation and velocity component distributions, showing that, as a consequence of the ejection process, the droplets responsible for the secondary peak have velocities uncorrelated with the mean flow. The fission is induced by the electric charge. When a droplet evaporates, in fact, the electric charge density on the droplet surface increases while the droplet shrinks, until the so-called Rayleigh limit is reached at which point the repulsion of electric charges overcomes the surface tension cohesive force, ultimately leading to a disintegraton into finer fragments. We report on the first observation of such fissions in combustion environments. If, on the other hand, insufficient evaporation has occurred before droplets enter the high temperature region, there appears to be no significant evidence of bimodality in their size distribution. In this case, in fact, the concentration of flame chemi-ions or, in the case of positively charged droplets, electrons may be sufficient for them to neutralize the charge on the droplets and to prevent disruption.
Anomalous growth of Ba on Ag(111)
International Nuclear Information System (INIS)
Teodoro, O.M.N.D.; Los, J.; Moutinho, A.M.C.
2002-01-01
Electropositive elements are often adsorbed on metals to produce a well-known decrease in the surface work function. During deposition, the work function drops steeply and reaches a minimum at coverage lower than one monolayer. Then, it increases slightly and the work function converges to the value of the deposited element. In this work, we report anomalous behavior found during the deposition of barium on a Ag(111) surface. After a minimum of about 2.4 eV the work function did not increase up to 2.7 eV, the bulk barium work function, no matter what amount of barium was deposited. Auger electron spectroscopy corroborated these results in which we measured a permanent and constant intensity of the Ag MNN peak for high barium coverage. To explain this anomalous growth of barium on Ag(111) we propose an explanation based on the diffusion of silver atoms into the barium film. Further experiments showed that coadsorption of oxygen before a second deposition of barium blocked the diffusion thus allowing the work function to reach 2.7 eV
A classical picture of anomalous effects in a tokamak
International Nuclear Information System (INIS)
Hirano, K.
1984-01-01
It is demonstrated that the atomic collisions between plasma ions and a very small amount of neutral particles remaining in a hot plasma plays a very important role for plasma transports and may be an origin of anomalous effects observed in a tokamak such as the diffusion coefficient independent of the field strength, a rapid plasma density increase during gas puffing and current penetration with anomalously high speed in the start-up phase. The Ohm's law derived by Cowling is used for the analysis. (author)
Anomalous feedback and negative domain wall resistance
International Nuclear Information System (INIS)
Cheng, Ran; Xiao, Di; Zhu, Jian-Gang
2016-01-01
Magnetic induction can be regarded as a negative feedback effect, where the motive-force opposes the change of magnetic flux that generates the motive-force. In artificial electromagnetics emerging from spintronics, however, this is not necessarily the case. By studying the current-induced domain wall dynamics in a cylindrical nanowire, we show that the spin motive-force exerting on electrons can either oppose or support the applied current that drives the domain wall. The switching into the anomalous feedback regime occurs when the strength of the dissipative torque β is about twice the value of the Gilbert damping constant α . The anomalous feedback manifests as a negative domain wall resistance, which has an analogy with the water turbine. (paper)
Shtukenberg, Alexander; Kahr, Bart
2007-01-01
Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...
Ferragut, Erik M.; Laska, Jason A.; Bridges, Robert A.
2016-06-07
A system is described for receiving a stream of events and scoring the events based on anomalousness and maliciousness (or other classification). The system can include a plurality of anomaly detectors that together implement an algorithm to identify low-probability events and detect atypical traffic patterns. The anomaly detector provides for comparability of disparate sources of data (e.g., network flow data and firewall logs.) Additionally, the anomaly detector allows for regulatability, meaning that the algorithm can be user configurable to adjust a number of false alerts. The anomaly detector can be used for a variety of probability density functions, including normal Gaussian distributions, irregular distributions, as well as functions associated with continuous or discrete variables.
Nagaoka, Katsumi; Yaginuma, Shin; Nakayama, Tomonobu
2018-02-01
We have discovered the condensation/diffusion phenomena of copper phthalocyanine (CuPc) molecules controlled with a pulsed electric field induced by the scanning tunneling microscope tip. This behavior is not explained by the conventional induced dipole model. In order to understand the mechanism, we have measured the electronic structure of the molecule by tunneling spectroscopy and also performed theoretical calculations on molecular orbitals. These data clearly indicate that the molecule is positively charged owing to charge transfer to the substrate, and that hydrogen bonding exists between CuPc molecules, which makes the molecular island stable.
Anomalous magnon Nernst effect of topological magnonic materials
Wang, X. S.; Wang, X. R.
2018-05-01
The magnon transport driven by a thermal gradient in a perpendicularly magnetized honeycomb lattice is studied. The system with the nearest-neighbor pseudodipolar interaction and the next-nearest-neighbor Dzyaloshinskii–Moriya interaction has various topologically nontrivial phases. When an in-plane thermal gradient is applied, a transverse in-plane magnon current is generated. This phenomenon is termed as the anomalous magnon Nernst effect that closely resembles the anomalous Nernst effect for an electronic system. The anomalous magnon Nernst coefficient and its sign are determined by the magnon Berry curvature distributions in the momentum space and magnon populations in the magnon bands. We predict a temperature-induced sign reversal in anomalous magnon Nernst effect under certain conditions.
Diffusion-induced bending of thin sheet couples : theory and experiments in Ti-Zr system
Daruka, I.; Szabo, I.A.; Beke, D.L.; Cserhati, C.; Kodentsov, A.; Loo, van, F.J.J.
1996-01-01
Numerical and analytical calculations of concentration and stress distributions of thin-sheet diffusion couples have been carried out as well as the time dependence of the Kirkendall shift, xk, and the curvature has also been determined. It is shown that the concentration distribution is not sensitive to the boundary conditions (bent and planar, constrained, samples) and is influenced mainly by the feeding back effects of stresses (described by the stress term in the genealized diffusion pote...
Kinowaki, Yuko; Kurata, Morito; Ishibashi, Sachiko; Ikeda, Masumi; Tatsuzawa, Anna; Yamamoto, Masahide; Miura, Osamu; Kitagawa, Masanobu; Yamamoto, Kouhei
2018-02-20
Regulation of oxidative stress and redox systems has important roles in carcinogenesis and cancer progression, and for this reason has attracted much attention as a new area of cancer therapeutic targets. Glutathione peroxidase 4 (GPX4), an antioxidant enzyme, has biological important functions such as signaling cell death by suppressing peroxidation of membrane phospholipids. However, few studies exist on the expression and clinical relevance of GPX4 in malignant lymphomas such as diffuse large B-cell lymphoma. In this study, we assessed the expression of GPX4 immunohistochemically. GPX4 was expressed in 35.5% (33/93) cases of diffuse large B-cell lymphoma. The GPX4-positive group had poor overall survival (P = 0.0032) and progression-free survival (P = 0.0004) compared with those of the GPX4-negative group. In a combined analysis of GPX4 and 8-hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, there was a negative correlation between GPX4 and 8-hydroxydeoxyguanosine (P = 0.0009). The GPX4-positive and 8-hydroxydeoxyguanosine-negative groups had a significantly worse prognosis than the other groups in both overall survival (P = 0.0170) and progression-free survival (P = 0.0005). These results suggest that the overexpression of GPX4 is an independent prognostic predictor in diffuse large B-cell lymphoma. Furthermore, in vitro analysis demonstrated that GPX4-overexpressing cells were resistant to reactive oxygen species-induced cell death (P = 0.0360). Conversely, GPX4-knockdown cells were sensitive to reactive oxygen species-induced cell death (P = 0.0111). From these data, we conclude that GPX4 regulates reactive oxygen species-induced cell death. Our results suggest a novel therapeutic strategy using the mechanism of ferroptosis, as well as a novel prognostic predictor of diffuse large B-cell lymphoma.
Disorder-induced transition from grain boundary to bulk dominated ionic diffusion in pyrochlores
International Nuclear Information System (INIS)
Perriot, Romain; Dholabhai, Pratik P.; Uberuaga, Blas P.
2017-01-01
In this paper, we use molecular dynamics simulations to investigate the role of grain boundaries (GBs) on ionic diffusion in pyrochlores, as a function of the GB type, chemistry of the compound, and level of cation disorder. We observe that the presence of GBs promotes oxygen transport in ordered and low-disordered systems, as the GBs are found to have a higher concentration of mobile carriers with higher mobilities than in the bulk. Thus, in ordered samples, the ionic diffusion is 2D, localized along the grain boundary. When cation disorder is introduced, bulk carriers begin to contribute to the overall diffusion, while the GB contribution is only slightly enhanced. In highly disordered samples, the diffusive behavior at the GBs is bulk-like, and the two contributions (bulk vs. GB) can no longer be distinguished. There is thus a transition from 2D/GB dominated oxygen diffusivity to 3D/bulk dominated diffusivity versus disorder in pyrochlores. Finally, these results provide new insights into the possibility of using internal interfaces to enhance ionic conductivity in nanostructured complex oxides.
Truong, Trong-Kha; Song, Allen W; Chen, Nan-Kuei
2015-01-01
In most diffusion tensor imaging (DTI) studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI) sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR). However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types of artifacts in partial-Fourier DTI. Here, we present an improved DTI acquisition and reconstruction scheme, capable of generating high-quality and high-SNR DTI data without eddy current-induced artifacts. This new scheme consists of three components, respectively, addressing the three distinct types of artifacts. First, a k-space energy-anchored DTI sequence is designed to recover eddy current-induced signal loss (i.e., Type 1 artifact). Second, a multischeme partial-Fourier reconstruction is used to eliminate artificial signal elevation (i.e., Type 2 artifact) associated with the conventional partial-Fourier reconstruction. Third, a signal intensity correction is applied to remove artificial signal modulations due to eddy current-induced erroneous T2(∗) -weighting (i.e., Type 3 artifact). These systematic improvements will greatly increase the consistency and accuracy of DTI measurements, expanding the utility of DTI in translational applications where quantitative robustness is much needed.
Nagaosa, Naoto; Sinova, Jairo; Onoda, Shigeki; MacDonald, A. H.; Ong, N. P.
2010-04-01
The anomalous Hall effect (AHE) occurs in solids with broken time-reversal symmetry, typically in a ferromagnetic phase, as a consequence of spin-orbit coupling. Experimental and theoretical studies of the AHE are reviewed, focusing on recent developments that have provided a more complete framework for understanding this subtle phenomenon and have, in many instances, replaced controversy by clarity. Synergy between experimental and theoretical works, both playing a crucial role, has been at the heart of these advances. On the theoretical front, the adoption of the Berry-phase concepts has established a link between the AHE and the topological nature of the Hall currents. On the experimental front, new experimental studies of the AHE in transition metals, transition-metal oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors have established systematic trends. These two developments, in concert with first-principles electronic structure calculations, strongly favor the dominance of an intrinsic Berry-phase-related AHE mechanism in metallic ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in terms of the Berry-phase curvatures and it is therefore an intrinsic quantum-mechanical property of a perfect crystal. An extrinsic mechanism, skew scattering from disorder, tends to dominate the AHE in highly conductive ferromagnets. The full modern semiclassical treatment of the AHE is reviewed which incorporates an anomalous contribution to wave-packet group velocity due to momentum-space Berry curvatures and correctly combines the roles of intrinsic and extrinsic (skew-scattering and side-jump) scattering-related mechanisms. In addition, more rigorous quantum-mechanical treatments based on the Kubo and Keldysh formalisms are reviewed, taking into account multiband effects, and demonstrate the equivalence of all three linear response theories in the metallic regime. Building on results from recent experiment and theory, a
Wang, Bo; Anthony, Stephen M; Bae, Sung Chul; Granick, Steve
2009-09-08
We describe experiments using single-particle tracking in which mean-square displacement is simply proportional to time (Fickian), yet the distribution of displacement probability is not Gaussian as should be expected of a classical random walk but, instead, is decidedly exponential for large displacements, the decay length of the exponential being proportional to the square root of time. The first example is when colloidal beads diffuse along linear phospholipid bilayer tubes whose radius is the same as that of the beads. The second is when beads diffuse through entangled F-actin networks, bead radius being less than one-fifth of the actin network mesh size. We explore the relevance to dynamic heterogeneity in trajectory space, which has been extensively discussed regarding glassy systems. Data for the second system might suggest activated diffusion between pores in the entangled F-actin networks, in the same spirit as activated diffusion and exponential tails observed in glassy systems. But the first system shows exceptionally rapid diffusion, nearly as rapid as for identical colloids in free suspension, yet still displaying an exponential probability distribution as in the second system. Thus, although the exponential tail is reminiscent of glassy systems, in fact, these dynamics are exceptionally rapid. We also compare with particle trajectories that are at first subdiffusive but Fickian at the longest measurement times, finding that displacement probability distributions fall onto the same master curve in both regimes. The need is emphasized for experiments, theory, and computer simulation to allow definitive interpretation of this simple and clean exponential probability distribution.
Anomalous and resonance small-angle scattering
International Nuclear Information System (INIS)
Epperson, J.E.; Thiyagarajan, P.
1988-01-01
Significant changes in the small-angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous-dispersion terms for the scattering factor (X-rays) or scattering length (neutrons). The physics inherent in these anomalous-dispersion terms is first discussed before consideration of how they enter the relevant scattering theory. Two major areas of anomalous-scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with X-rays. However, it is pointed out that the formalism is the same for the analog experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scattering are discussed. (orig.)
Lung injury induced by secondhand smoke exposure detected with hyperpolarized helium-3 diffusion MR.
Wang, Chengbo; Mugler, John P; de Lange, Eduard E; Patrie, James T; Mata, Jaime F; Altes, Talissa A
2014-01-01
To determine whether helium-3 diffusion MR can detect the changes in the lungs of healthy nonsmoking individuals who were regularly exposed to secondhand smoke. Three groups were studied (age: 59 ± 9 years): 23 smokers, 37 exposure-to-secondhand-smoke subjects, and 29 control subjects. We measured helium-3 diffusion values at diffusion times from 0.23 to 1.97 s. One-way analysis of variance revealed that the mean area under the helium-3 diffusion curves (ADC AUC) of the smokers was significantly elevated compared with the controls and to the exposure-to-secondhand-smoke subjects (P exposure-to-secondhand-smoke subjects and that of the controls was found (P = 0.115). However, application of a receiver operator characteristic-derived rule to classify subjects as either a "control" or a "smoker," based on ADC AUC, revealed that 30% (11/37) of the exposure-to-secondhand subjects were classified as "smokers" indicating an elevation of the ADC AUC. Using helium-3 diffusion MR, elevated ADC values were detected in 30% of nonsmoking healthy subjects who had been regularly exposed to secondhand smoke, supporting the concept that, in susceptible individuals, secondhand smoke causes mild lung damage. Copyright © 2013 Wiley Periodicals, Inc.
DEFF Research Database (Denmark)
Møldrup, Per; Chamindu, T. K. K. Deepagoda; Hamamoto, S.
2013-01-01
The soil-gas diffusion is a primary driver of transport, reactions, emissions, and uptake of vadose zone gases, including oxygen, greenhouse gases, fumigants, and spilled volatile organics. The soil-gas diffusion coefficient, Dp, depends not only on soil moisture content, texture, and compaction...... but also on the local-scale variability of these. Different predictive models have been developed to estimate Dp in intact and repacked soil, but clear guidelines for model choice at a given soil state are lacking. In this study, the water-induced linear reduction (WLR) model for repacked soil is made...... air) in repacked soils containing between 0 and 54% clay. With Cm = 2.1, the SWLR model on average gave excellent predictions for 290 intact soils, performing well across soil depths, textures, and compactions (dry bulk densities). The SWLR model generally outperformed similar, simple Dp/Do models...
Anomalous spreading behaviour of polyethyleneglycoldistearate ...
Indian Academy of Sciences (India)
Unknown
Anomalous behaviour; polythyleneglycoldistearate; air/water interface; ... distinguished these monolayer states in terms of molecular ordering, including the .... It has been found that the compressibilities of the materials in the condensed phase.
Modeling of Ni Diffusion Induced Austenite Formation in Ferritic Stainless Steel Interconnects
DEFF Research Database (Denmark)
Chen, Ming; Alimadadi, Hossein; Molin, Sebastian
2017-01-01
Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell and electrolysis cell stacks. During stack production and operation, nickel from the Ni/yttria stabilized zirconia fuel electrode or from the Ni contact component layer diffuses into the interconnect plate......, causing transformation of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume, and in mechanical and corrosion properties of the interconnect plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic...
Isospin diffusion in 58Ni-induced reactions at intermediate energies. I. Experimental results
International Nuclear Information System (INIS)
Galichet, E.; Rivet, M. F.; Borderie, B.; Colonna, M.; Bougault, R.; Durand, D.; Lopez, O.; Manduci, L.; Tamain, B.; Vient, E.; Chbihi, A.; Frankland, J. D.; Wieleczko, J. P.; Dayras, R.; Volant, C.; Guinet, D. C. R.; Lautesse, P.; Neindre, N. Le; Parlog, M.; Rosato, E.
2009-01-01
Isospin diffusion in semiperipheral collisions is probed as a function of the dissipated energy by studying two systems 58 Ni+ 58 Ni and 58 Ni+ 197 Au, over the incident energy range 52A-74A MeV. A close examination of the multiplicities of light products in the forward part of the phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time.
Modeling of Ni Diffusion Induced Austenite Formation in Ferritic Stainless Steel Interconnects
DEFF Research Database (Denmark)
Chen, Ming; Molin, Sebastian; Zhang, L.
2015-01-01
Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell (SOFC) or electrolysis cell (SOEC) stacks. During stack production and operation, nickel from the Ni/YSZ fuel electrode or from the Ni contact component diffuses into the IC plate, causing transformation...... of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume and in mechanical and corrosion properties of the IC plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic stainless steel was conducted, using the CALPHAD...
Anomalous magnetoresistance in amorphous metals
International Nuclear Information System (INIS)
Kuz'menko, V.M.; Vladychkin, A.N.; Mel'nikov, V.I.; Sudovtsev, A.I.
1984-01-01
The magnetoresistance of amorphous Bi, Ca, V and Yb films is investigated in fields up to 4 T at low temperatures. For all metals the magnetoresistance is positive, sharply decreases with growth of temperature and depends anomalously on the magnetic field strength. For amorphous superconductors the results agree satisfactorily with the theory of anomalous magnetoresistance in which allowance is made for scattering of electrons by the superconducting fluctuations
Navigation by anomalous random walks on complex networks.
Weng, Tongfeng; Zhang, Jie; Khajehnejad, Moein; Small, Michael; Zheng, Rui; Hui, Pan
2016-11-23
Anomalous random walks having long-range jumps are a critical branch of dynamical processes on networks, which can model a number of search and transport processes. However, traditional measurements based on mean first passage time are not useful as they fail to characterize the cost associated with each jump. Here we introduce a new concept of mean first traverse distance (MFTD) to characterize anomalous random walks that represents the expected traverse distance taken by walkers searching from source node to target node, and we provide a procedure for calculating the MFTD between two nodes. We use Lévy walks on networks as an example, and demonstrate that the proposed approach can unravel the interplay between diffusion dynamics of Lévy walks and the underlying network structure. Moreover, applying our framework to the famous PageRank search, we show how to inform the optimality of the PageRank search. The framework for analyzing anomalous random walks on complex networks offers a useful new paradigm to understand the dynamics of anomalous diffusion processes, and provides a unified scheme to characterize search and transport processes on networks.
Navigation by anomalous random walks on complex networks
Weng, Tongfeng; Zhang, Jie; Khajehnejad, Moein; Small, Michael; Zheng, Rui; Hui, Pan
2016-11-01
Anomalous random walks having long-range jumps are a critical branch of dynamical processes on networks, which can model a number of search and transport processes. However, traditional measurements based on mean first passage time are not useful as they fail to characterize the cost associated with each jump. Here we introduce a new concept of mean first traverse distance (MFTD) to characterize anomalous random walks that represents the expected traverse distance taken by walkers searching from source node to target node, and we provide a procedure for calculating the MFTD between two nodes. We use Lévy walks on networks as an example, and demonstrate that the proposed approach can unravel the interplay between diffusion dynamics of Lévy walks and the underlying network structure. Moreover, applying our framework to the famous PageRank search, we show how to inform the optimality of the PageRank search. The framework for analyzing anomalous random walks on complex networks offers a useful new paradigm to understand the dynamics of anomalous diffusion processes, and provides a unified scheme to characterize search and transport processes on networks.
Daniels, Marcus G.; Farmer, J. Doyne; Gillemot, László; Iori, Giulia; Smith, Eric
2003-03-01
We model trading and price formation in a market under the assumption that order arrival and cancellations are Poisson random processes. This model makes testable predictions for the most basic properties of markets, such as the diffusion rate of prices (which is the standard measure of financial risk) and the spread and price impact functions (which are the main determinants of transaction cost). Guided by dimensional analysis, simulation, and mean-field theory, we find scaling relations in terms of order flow rates. We show that even under completely random order flow the need to store supply and demand to facilitate trading induces anomalous diffusion and temporal structure in prices.
Observations of anomalous fading in maiolica
International Nuclear Information System (INIS)
Bowman, S.G.E.
1988-01-01
In the course of an authenticity study on Italian maiolica (tin-glazed earthenware of the Renaissance period), storage at elevated temperature was used to accelerate anomalous fading. Substantial levels of fading were observed in about half of the samples, and in these cases the variation of fading with glow curve temperature accounted for the lack of an equivalent dose plateau. Some evidence was found for a difference in the fading between alpha and beta induced thermoluminescence (TL). More importantly, some samples with unstable natural TL were found: the implications of this for dating and the circumvention of fading are discussed. (author)
DEFF Research Database (Denmark)
Svenson, Mouritz Nolsøe; Thirion, Lynn M.; Youngman, Randall E.
chamber to compress bulk glass samples isostatically up to 1 GPa at elevated temperature before or after the ion exchange treatment of an industrial sodium-magnesium aluminosilicate glass. Compression of the samples prior to ion exchange leads to a decreased Na+-K+ inter-diffusivity, increased compressive...
Circulation induced by diffused aeration in a shallow lake | Toné ...
African Journals Online (AJOL)
Field surveys were carried out to investigate the surface jet flows and the resulting circulation patterns generated by diffused aeration in a shallow lake. In conrast to previous studies, the experimental conditions included point-source bubble plumes with very high air flow rates (100–400 L/min) relative to the shallow water ...
Diffusion coefficients for periodically induced multi-step persistent walks on regular lattices
International Nuclear Information System (INIS)
Gilbert, Thomas; Sanders, David P
2012-01-01
We present a generalization of our formalism for the computation of diffusion coefficients of multi-step persistent random walks on regular lattices to walks which include zero-displacement states. This situation is especially relevant to systems where tracer particles move across potential barriers as a result of the action of a periodic forcing whose period sets the timescale between transitions. (paper)
Diffusion-induced bending of thin sheet couples : theory and experiments in Ti-Zr system
Daruka, I.; Szabo, I.A.; Beke, D.L.; Cserhati, C.; Kodentsov, A.; Loo, van F.J.J.
1996-01-01
Numerical and analytical calculations of concentration and stress distributions of thin-sheet diffusion couples have been carried out as well as the time dependence of the Kirkendall shift, xk, and the curvature has also been determined. It is shown that the concentration distribution is not
Cyclic steady states in diffusion-induced plasticity with applications to lithium-ion batteries
Peigney, Michaël
2018-02-01
Electrode materials in lithium-ion batteries offer an example of medium in which stress and plastic flow are generated by the diffusion of guest atoms. In such a medium, deformation and diffusion are strongly coupled processes. For designing electrodes with improved lifetime and electro-mechanical efficiency, it is crucial to understand how plasticity and diffusion evolve over consecutive charging-recharging cycles. With such questions in mind, this paper provides general results for the large-time behavior of media coupling plasticity with diffusion when submitted to cyclic chemo-mechanical loadings. Under suitable assumptions, we show that the stress, the plastic strain rate, the chemical potential and the flux of guest atoms converge to a cyclic steady state which is largely independent of the initial state. A special emphasis is laid on the special case of elastic shakedown, which corresponds to the situation where the plastic strain stops evolving after a sufficiently large number of cycles. Elastic shakedown is expected to be beneficial for the fatigue behavior and - in the case of lithium-ion batteries - for the electro-chemical efficiency. We provide a characterization of the chemo-mechanical loadings for which elastic shakedown occurs. Building on that characterization, we suggest a general method for designing structures in such fashion that they operate in the elastic shakedown regime, whatever the initial state is. An attractive feature of the proposed method is that incremental analysis of the fully coupled plasticity-diffusion problem is avoided. The results obtained are applied to the model problem of a battery electrode cylinder particle under cyclic charging. Closed-form expressions are obtained for the set of charging rates and charging amplitudes for which elastic shakedown occurs, as well as for the corresponding cyclic steady states of stress, lithium concentration and chemical potential. Some results for a spherical particle are also presented.
International Nuclear Information System (INIS)
Malinenko, I.A.; Perelygina, E.A.; Chudinova, S.A.; Shivrin, O.N.
1979-01-01
The method of X-ray diffusion scattering was used to study the defective structure of germanium monocrystals exposed to 750 keV proton irradiation with 3.8x10 16 -4.6x10 17 cm -2 doses and subjected to the subsequent annealing at temperatures up to 450 deg C. Detected in the crystals were the complex radiation induced structure characterized with oriented vacancy complexes and results from the both effects: irradiation and annealing. Radiation defect sizes in the section (hhO) have been determined. With increasing the annealing temperature the structure reconstruction resulting in the complex dissociation is observed
New Insights into the Origins of Sb-Induced Effects on Self-Catalyzed GaAsSb Nanowire Arrays
DEFF Research Database (Denmark)
Ren, Dingding; Dheeraj, Dasa L.; Jin, Chengjun
2016-01-01
and thermodynamically by the introduction of Sb. An anomalous decrease of the axial growth rate with increased Sb2 flux is found to be due to both the indirect kinetic influence via the Ga adatom diffusion induced catalyst geometry evolution and the direct composition modulation. From the fundamental growth analyses...
Anomalous Price Impact and the Critical Nature of Liquidity in Financial Markets
Tóth, B.; Lempérière, Y.; Deremble, C.; de Lataillade, J.; Kockelkoren, J.; Bouchaud, J.-P.
2011-10-01
We propose a dynamical theory of market liquidity that predicts that the average supply/demand profile is V shaped and vanishes around the current price. This result is generic, and only relies on mild assumptions about the order flow and on the fact that prices are, to a first approximation, diffusive. This naturally accounts for two striking stylized facts: First, large metaorders have to be fragmented in order to be digested by the liquidity funnel, which leads to a long memory in the sign of the order flow. Second, the anomalously small local liquidity induces a breakdown of the linear response and a diverging impact of small orders, explaining the “square-root” impact law, for which we provide additional empirical support. Finally, we test our arguments quantitatively using a numerical model of order flow based on the same minimal ingredients.
Anomalous Price Impact and the Critical Nature of Liquidity in Financial Markets
Directory of Open Access Journals (Sweden)
B. Tóth
2011-10-01
Full Text Available We propose a dynamical theory of market liquidity that predicts that the average supply/demand profile is V shaped and vanishes around the current price. This result is generic, and only relies on mild assumptions about the order flow and on the fact that prices are, to a first approximation, diffusive. This naturally accounts for two striking stylized facts: First, large metaorders have to be fragmented in order to be digested by the liquidity funnel, which leads to a long memory in the sign of the order flow. Second, the anomalously small local liquidity induces a breakdown of the linear response and a diverging impact of small orders, explaining the “square-root” impact law, for which we provide additional empirical support. Finally, we test our arguments quantitatively using a numerical model of order flow based on the same minimal ingredients.
Anomalous frequency-dependent ionic conductivity of lesion-laden human-brain tissue
Emin, David; Akhtari, Massoud; Fallah, Aria; Vinters, Harry V.; Mathern, Gary W.
2017-10-01
We study the effect of lesions on our four-electrode measurements of the ionic conductivity of (˜1 cm3) samples of human brain excised from patients undergoing pediatric epilepsy surgery. For most (˜94%) samples, the low-frequency ionic conductivity rises upon increasing the applied frequency. We attributed this behavior to the long-range (˜0.4 mm) diffusion of solvated sodium cations before encountering intrinsic impenetrable blockages such as cell membranes, blood vessels, and cell walls. By contrast, the low-frequency ionic conductivity of some (˜6%) brain-tissue samples falls with increasing applied frequency. We attribute this unusual frequency-dependence to the electric-field induced liberation of sodium cations from traps introduced by the unusually severe pathology observed in samples from these patients. Thus, the anomalous frequency-dependence of the ionic conductivity indicates trap-producing brain lesions.
Nonlinear saturation of dissipative trapped ion instability and anomalous transport
International Nuclear Information System (INIS)
Sugihara, Masayoshi; Ogasawara, Masatada.
1977-04-01
An expression for the turbulent collision frequency is derived by summing up the most dominant terms from each order in the perturbation expansion in order to obtain the nonlinear saturation level of the dissipative trapped ion instability. Numerical calculation shows that the anomalous diffusion coefficient at the saturated state is in good agreement with the result of Kadomtsev and Pogutse when the effect of the magnetic shear is taken into account. (auth.)
International Nuclear Information System (INIS)
Butenhoff, T.J.
1994-01-01
Hydrothermal processing is being developed as a method for organic destruction for the Hanford Site in Washington. Hydrothermal processing refers to the redox reactions of chemical compounds in supercritical or near-supercritical aqueous solutions. In order to design reactors for the hydrothermal treatment of complicated mixtures found in the Hanford wastes, engineers need to know the thermophysical properties of the solutions under hydrothermal conditions. The author used the laser-induced grating technique to measure the thermal diffusivity and speed of sound of hydrothermal solutions. In this non-invasive optical technique, a transient grating is produced in the hydrothermal solution by optical absorption from two crossed time-coincident nanosecond laser pulses. The grating is probed by measuring the diffraction efficiency of a third laser beam. The grating relaxes via thermal diffusion, and the thermal diffusivity can be determined by measuring the decay of the grating diffraction efficiency as a function of the pump-probe delay time. In addition, intense pump pulses produce counterpropagating acoustic waves that appear as large undulations in the transient grating decay spectrum. The speed of sound in the sample is simply the grating fringe spacing divided by the undulation period. The cell is made from a commercial high pressure fitting and is equipped with two diamond windows for optical access. Results are presented for dilute dye/water solutions with T = 400 C and pressures between 20 and 70 MPa
International Nuclear Information System (INIS)
Lee, K.R.
1992-01-01
This paper reports that when a 90Mo-10Ni alloy (by wt) liquid phase sintered at 1400 degrees C is heat-treated at 1400 degrees C after replacing the matrix with a melt of 44Ni-34Mo-22W (by wt), the liquid films between the grains migrate, leaving behind an Mo alloy enriched with W. The ratio of the lattice diffusivity of W in Mo, D, to the initial migration velocity, v. (D/v) is estimated to be between 0.03 and 0.18 angstrom. Hence it appears that there is no lattice diffusion of W ahead of the migrating liquid film, and is such a case the driving force has been suggested to be the chemical free energy. But the observed v is approximately same as that to be expected if the driving force is assumed to be diffusional coherency strain energy. Likewise, a previous study of den Broeder and Nakahara shows that the rate of chemically-induced grain boundary migration in Cu-Ni shows a smooth variation with temperature as D/v decreases from values much larger than the interatomic spacing to values much smaller with decreasing temperature. The coherency strain energy thus appears to be a general driving force for the migration even when the apparent diffusion length indicated by D/v is smaller than the interatomic spacing
Zhou, Nan; Guo, Tingting; Zheng, Huanhuan; Pan, Xia; Chu, Chen; Dou, Xin; Li, Ming; Liu, Song; Zhu, Lijing; Liu, Baorui; Chen, Weibo; He, Jian; Yan, Jing; Zhou, Zhengyang; Yang, Xiaofeng
2017-09-19
We investigated apparent diffusion coefficient (ADC) histogram analysis to evaluate radiation-induced parotid damage and predict xerostomia degrees in nasopharyngeal carcinoma (NPC) patients receiving radiotherapy. The imaging of bilateral parotid glands in NPC patients was conducted 2 weeks before radiotherapy (time point 1), one month after radiotherapy (time point 2), and four months after radiotherapy (time point 3). From time point 1 to 2, parotid volume, skewness, and kurtosis decreased ( P histogram parameters increased (all P histogram parameters. Early mean change rates for bilateral parotid SD and ADC max could predict late xerostomia degrees at seven months after radiotherapy (three months after time point 3) with AUC of 0.781 and 0.818 ( P = 0.014, 0.005, respectively). ADC histogram parameters were reproducible (intraclass correlation coefficient, 0.830 - 0.999). ADC histogram analysis could be used to evaluate radiation-induced parotid damage noninvasively, and predict late xerostomia degrees of NPC patients treated with radiotherapy.
Dichotomous-noise-induced pattern formation in a reaction-diffusion system
Das, Debojyoti; Ray, Deb Shankar
2013-06-01
We consider a generic reaction-diffusion system in which one of the parameters is subjected to dichotomous noise by controlling the flow of one of the reacting species in a continuous-flow-stirred-tank reactor (CSTR) -membrane reactor. The linear stability analysis in an extended phase space is carried out by invoking Furutzu-Novikov procedure for exponentially correlated multiplicative noise to derive the instability condition in the plane of the noise parameters (correlation time and strength of the noise). We demonstrate that depending on the correlation time an optimal strength of noise governs the self-organization. Our theoretical analysis is corroborated by numerical simulations on pattern formation in a chlorine-dioxide-iodine-malonic acid reaction-diffusion system.
Migration of liquid film and grain boundary in Mo-Ni induced by W diffusion
International Nuclear Information System (INIS)
Kang, H.K.; Hackney, S.; Yoon, D.N.
1988-01-01
The liquid films and grain boundaries in liquid phase sintered Mo-Ni alloy are observed to migrate during heat-treatment after adding W to the liquid matrix. Behind the migrating boundaries forms Mo-Ni-W solid solution with the W concentration decreasing with the migration distance because of W depletion in the liquid matrix. The migration rate during the heat-treatment at 1540 0 C after adding W decreases with the decreasing pretreatment sintering temperature. When the sintering temperature is 1420 0 C, the migration rate is almost reduced to O. Under this condition, the coherency strain due to the simultaneous diffusion of W and Ni into the grain surfaces is estimated to be almost O. The results thus show that the coherency strain due to lattice diffusion is the driving force for the liquid film and grain boundary migration
Effect of lattice mismatch-induced strains on coupled diffusive and displacive phase transformations
Bouville, Mathieu; Ahluwalia, Rajeev
2006-01-01
Materials which can undergo slow diffusive transformations as well as fast displacive transformations are studied using the phase-field method. The model captures the essential features of the time-temperature-transformation (TTT) diagrams, continuous cooling transformation (CCT) diagrams, and microstructure formation of these alloys. In some materials systems there can exist an intrinsic volume change associated with these transformations. We show that these coherency strains can stabilize m...
Czech Academy of Sciences Publication Activity Database
Šlais, Karel; Voříšek, Ivan; Zoremba, N.; Homola, Aleš; Dmytrenko, Lesia; Syková, Eva
2008-01-01
Roč. 209, č. 1 (2008), s. 145-154 ISSN 0014-4886 R&D Projects: GA MŠk 1M0538; GA MŠk(CZ) LC554 Grant - others:EU(DE) 512146 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z50390703 Source of funding: R - rámcový projekt EK Keywords : Diffusion * Microdialysis * Pilocarpine Subject RIV: FH - Neurology Impact factor: 3.974, year: 2008
Energy Technology Data Exchange (ETDEWEB)
Gharooni, M.; Hosseini, M.; Mohajerzadeh, S., E-mail: mohajer@ut.ac.ir; Taghinejad, M.; Taghinejad, H. [Thin Film and Nanoelectronics Lab, Nanoelectronics Center of Excellence, School of Electrical and Computer Engineering, University of Tehran, Tehran 143957131 (Iran, Islamic Republic of); Abdi, Y. [Nano-Physics Research Lab, Department of Physics, University of Tehran, Tehran 1439955961 (Iran, Islamic Republic of)
2014-07-28
Morphologically controlled nanostructures have been increasingly important because of their strongly shape dependent physical and chemical properties. Formation of nanoscale silicon based structures that employ high levels of strain, intentional, and unintentional twins or grain boundaries can be dramatically different from the commonly conceived bulk processes. We report, realization of highly crystallographic 3D nanosheets with unique morphology and ultra-thin thickness by a stress-induced oriented-diffusion method, based on plasma processing of metal layer deposited on Si substrate and its post deep reactive ion etching. Annealing in plasma ambient creates rod-like metal alloy precursors which induce stress at its interface with Si substrate due to the mismatch of lattice constants. This stress opens facilitated gateways for orientated-diffusion of metal atoms in 〈110〉 directions and leads to formation of NSs (nanosheets) with [111] crystalline essence. Nanosheets are mainly triangular, hexagonal, or pseudo hexagonal in shape and their thicknesses are well controlled from several to tens of nanometers. The structural and morphological evolution of features were investigated in detail using transmission electron microscope, atomic force microscope, scanning electron microscope and possible mechanism is proposed to explain the formation of the thermodynamically unfavorable morphology of nanosheets. Significant photoemission capability of NSs was also demonstrated by photoluminescence spectroscopy.
Directory of Open Access Journals (Sweden)
Swarupa Kancherla
Full Text Available Visual function has been shown to deteriorate prior to the onset of retinopathy in some diabetic patients and experimental animal models. This suggests the involvement of the brain's visual system in the early stages of diabetes. In this study, we tested this hypothesis by examining the integrity of the visual pathway in a diabetic rat model using in vivo multi-modal magnetic resonance imaging (MRI. Ten-week-old Sprague-Dawley rats were divided into an experimental diabetic group by intraperitoneal injection of 65 mg/kg streptozotocin in 0.01 M citric acid, and a sham control group by intraperitoneal injection of citric acid only. One month later, diffusion tensor MRI (DTI was performed to examine the white matter integrity in the brain, followed by chromium-enhanced MRI of retinal integrity and manganese-enhanced MRI of anterograde manganese transport along the visual pathway. Prior to MRI experiments, the streptozotocin-induced diabetic rats showed significantly smaller weight gain and higher blood glucose level than the control rats. DTI revealed significantly lower fractional anisotropy and higher radial diffusivity in the prechiasmatic optic nerve of the diabetic rats compared to the control rats. No apparent difference was observed in the axial diffusivity of the optic nerve, the chromium enhancement in the retina, or the manganese enhancement in the lateral geniculate nucleus and superior colliculus between groups. Our results suggest that streptozotocin-induced diabetes leads to early injury in the optic nerve when no substantial change in retinal integrity or anterograde transport along the visual pathways was observed in MRI using contrast agent enhancement. DTI may be a useful tool for detecting and monitoring early pathophysiological changes in the visual system of experimental diabetes non-invasively.
International Nuclear Information System (INIS)
Aydemir, A.Y.
1990-01-01
We derive the dispersion relations for both small and large-Δ' modes (m ≥ 2, and m = 1 modes, respectively) driven by anomalous electron viscosity. Under the assumption that the anomalous kinematic electron viscosity is comparable to the anomalous electron thermal diffusivity, we find that the viscous mode typically has a higher growth rate than the corresponding resistive mode. We compare computational results in cylindrical and toroidal geometries with theory and present some nonlinear results for viscous m = 1 modes in both circular and D-shaped boundaries and discuss their possible rile in fast sawtooth crashes. 30 ref., 5 figs., 1 tab
International Nuclear Information System (INIS)
Wolf, R.; Pretschner, P.; Engel, H.J.; Hundeshagen, H.; Lichtlen, P.R.; Medizinische Hochschule Hannover
1979-01-01
The effect of isosorbide dinitrate (ISDN) (10 mg sublingually) on myocardial perfusion under ischemic conditions was analyzed in 14 patients with angiographically severe coronary artery disease and typical angina pectoris, using 201-thallium-myocardial scintiscanning. All patients underwent two identical scintiscans with the same work load during bicycle ergometry; a control scintiscan leading to angina and ST-depressions of > 0.1 mV was followed 4-6 weeks later by a scintiscan after ISDN; all drugs - except sublingual nitroglycerin - were withheld for an entire week. - Results: 25 of 39 new or enlarged, exercise-induced defects (64%) were normalized after ISDN; 14 new or enlarged defects remained unchanged (p [de
International Nuclear Information System (INIS)
Wendin, G.
1979-01-01
The availability of tunable synchrotron radiation has made it possible systematically to perform x-ray diffraction studies in regions of anomalous scattering near absorption edges, e.g. in order to derive phase information for crystal structure determination. An overview is given of recent experimental and theoretical work and discuss the properties of the anomalous atomic scattering factor, with emphasis on threshold resonances and damping effects. The results are applied to a discussion of the very strong anomalous dispersion recently observed near the L 3 edge in a cesium complex. Also given is an overview of elements and levels where similar behavior can be expected. Finally, the influence of solid state and chemical effects on the absorption edge structure is discussed. 64 references
Diffusion-induced periodic transition between oscillatory modes in amplitude-modulated patterns
Energy Technology Data Exchange (ETDEWEB)
Tang, Xiaodong; He, Yuxiu; Wang, Shaorong; Gao, Qingyu, E-mail: gaoqy@cumt.edu.cn [College of Chemical Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Epstein, Irving R., E-mail: epstein@brandeis.edu [Department of Chemistry and Volen Center for Complex Systems, MS 015, Brandeis University, Waltham, Massachusetts 02454-9110 (United States); Wang, Qun [School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116 (China)
2014-06-15
We study amplitude-modulated waves, e.g., wave packets in one dimension, overtarget spirals and superspirals in two dimensions, under mixed-mode oscillatory conditions in a three-variable reaction-diffusion model. New transition zones, not seen in the homogeneous system, are found, in which periodic transitions occur between local 1{sup N−1} and 1{sup N} oscillations. Amplitude-modulated complex patterns result from periodic transition between (N − 1)-armed and N-armed waves. Spatial recurrence rates provide a useful guide to the stability of these modulated patterns.
Strobel, D. F.; Apruzese, J. P.; Schoeberl, M. R.
1985-01-01
The constraints on turbulence improved by the mesospheric heat budget are reexamined, and the sufficiency of the theoretical evidence to support the hypothesis that the eddy Prandtl number is greater than one in the mesosphere is considered. The mesopause thermal structure is calculated with turbulent diffusion coefficients commonly used in chemical models and deduced from mean zonal wind deceleration. It is shown that extreme mesopause temperatures of less than 100 K are produced by the large net cooling. The results demonstrate the importance of the Prandtl number for mesospheric turbulence.
Reactions and Diffusion During Annealing-Induced H(+) Generation in SOI Buried Oxides
International Nuclear Information System (INIS)
Devine, R.A.B.; Fleetwood, D.M.; Vanheusden, K; Warren, W.L.
1999-01-01
We report experimental results suggesting that mobile protons are generated at strained Si-O-Si bonds near the Si/SiO 2 interface during annealing in forming gas. Our data further suggest that the presence of the top Si layer plays a crucial role in the mobile H + generation process. Finally, we show that the diffusion of the reactive species (presumably H 2 or H 0 ) towards the H + generation sites occurs laterally along the buried oxide layer, and can be impeded significantly due to the presence of trapping sites in the buried oxide
Enhancement in anomalous Hall resistivity of Co/Pd multilayer and CoPd alloy by Ga+ ion irradiation
Guo, Zaibing
2014-02-01
In this paper, we report the effect of Ga+ ion irradiation on anomalous Hall effect (AHE) and longitudinal resistivity (ρxx) in [Co(3 Å)/Pd(5 Å)]80 multilayer and Co 42Pd58 alloy. 4- and 2-fold increases in anomalous Hall resistivity (ρAH) in the Co/Pd multilayer and CoPd alloy have been observed after irradiations at doses of 2.4 × 1015 and 3.3×10 15 ions/cm2, respectively. Skew scattering and side jump contributions to AHE have been analyzed based on the scaling relationship ρAH = aρxx + bρ2xx. For the Co/Pd multilayer, AHE is mainly affected by ion irradiation-induced interface diffusion and defects. For the CoPd alloy, the increase in doses above 1.5 × 1015 ions/cm2 induces a sign change in skew scattering, followed by the skew scattering contribution to AHE overwhelming the side jump contribution, this phenomenon should be attributed to irradiation-induced defects and modifications in chemical ordering. © Copyright EPLA, 2014.
Anomalous tensoelectric effects in gallium arsenide tunnel diodes
Energy Technology Data Exchange (ETDEWEB)
Alekseeva, Z.M.; Vyatkin, A.P.; Krivorotov, N.P.; Shchegol' , A.A.
1988-02-01
Anomalous tensoelectric phenomena induced in a tunnel p-n junction by a concentrated load and by hydrostatic compression were studied. The anomalous tensoelectric effects are caused by the action of concentrators of mechanical stresses in the vicinity of the p-n junction, giving rise to local microplastic strain. Under the conditions of hydrostatic compression prolate inclusions approx.100-200 A long play the role of concentrators. Analysis of irreversible changes in the current-voltage characteristics of tunnel p-n junctions made it possible to separate the energy levels of the defects produced with plastic strain of gallium arsenide.
International Nuclear Information System (INIS)
Fayolle, D.
2002-01-01
In its second phase, LEP has allowed to study four fermion processes never observed before. Results are presented on the charged triple gauge boson couplings (TGC) from the W-pair, Single W and Single γ production. The anomalous quartic gauge couplings (QGC) are constrained using production of WWγ, νν-barγγ and Z γγ final states. Finally, limits on the neutral anomalous gauge couplings (NGC) using the Z γ and ZZ production processes are also reported. All results are consistent with the Standard Model expectations. (authors)
Computer simulations of anomalous transport
International Nuclear Information System (INIS)
Lee, W.W.; Okuda, H.
1980-07-01
Numerical plasma simulations have been carried out to study: (1) the turbulent spectrum and anomalous plasma transport associated with a steady state electrostatic drift turbulence; and (2) the anomalous energy transport of electrons due to shear-Alfven waves in a finite-β plasma. For the simulation of the steady state drift turbulence, it is observed that, in the absence of magnetic shear, the turbulence is quenched to a low level when the rotational transform is a rational number, while the turbulent level remains high for an irrational rotational transform
Diffraction anomalous fine structure using X-ray anomalous dispersion
International Nuclear Information System (INIS)
Soejima, Yuji; Kuwajima, Shuichiro
1998-01-01
A use of X-ray anomalous dispersion effects for structure investigation has recently been developed by using synchrotron radiation. One of the interesting method is the observation of anomalous fine structure which arise on diffraction intensity in energy region of incident X-ray at and higher than absorption edge. The phenomenon is so called Diffraction Anomalous Fine Structure (DAFS). DAFS originates in the same physical process an that of EXAFS: namely photoelectric effect at the corresponding atom and the interaction of photoelectron waves between the atom and neighboring atoms. In contrast with EXAFS, the method is available for only the crystalline materials, but shows effective advantages of the structure investigations by a use of diffraction: one is the site selectivity and the other is space selectivity. In the present study, demonstrations of a use of X-ray anomalous dispersion effect for the superstructure determination will be given for the case of PbZrO 3 , then recent trial investigations of DAFS in particular on the superlattice reflections will be introduced. In addition, we discuss about Forbidden Reflection near Edge Diffraction (FRED) which is more recently investigated as a new method of the structure analysis. (author)
High temperature diffusion induced liquid phase joining of a heat resistant alloy
International Nuclear Information System (INIS)
Wikstrom, N.P.; Egbewande, A.T.; Ojo, O.A.
2008-01-01
Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, t f, required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 deg. C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures
Observations of Anomalous Refraction with Co-housed Telescopes
Taylor, Malinda S.; McGraw, J. T.; Zimmer, P. C.
2013-01-01
Anomalous refraction is described as a low frequency, large angular scale motion of the entire image plane with respect to the celestial coordinate system as observed and defined by previous astrometric catalogs. These motions of typically several tenths of an arcsecond with timescales on the order of ten minutes are ubiquitous to drift-scan ground-based astrometric measurements regardless of location or telescopes used and have been attributed to meter scale slowly evolving coherent dynamical structures in the boundary-layer below 60 meters. The localized nature of the effect and general inconsistency of the motions seen by even closely spaced telescopes in individual domes has led to the hypothesis that the dome or other type of telescope housing may be responsible. This hypothesis is tested by observing anomalous refraction using two telescopes housed in a single roll-off roof observatory building with the expected outcome that the two telescopes will see correlated anomalous refraction induced motions.
Neoclassical and anomalous transport in axisymmetric toroidal plasmas with electrostatic turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1995-01-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electrostatic fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear term. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. The neoclassical banana-plateau particle and heat fluxes and the bootstrap current are also affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The quasilinear term, the anomalous forces, and the anomalous particle and heat fluxes are evaluated from the fluctuating part of the drift kinetic equation. The averaged drift kinetic equation with the quasilinear term is solved for the plateau regime to derive the parallel viscosities modified by the fluctuations. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. copyright 1995 American Institute of Physics
Wang, H-Z; Qiu, S-J; Lv, X-F; Wang, Y-Y; Liang, Y; Xiong, W-F; Ouyang, Z-B
2012-04-01
To investigate the metabolic characteristics of the temporal lobes following radiation therapy for nasopharyngeal carcinoma using diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy ((1)H-MRS). DTI and (1)H-MRS were performed in 48 patients after radiotherapy for nasopharyngeal carcinoma and in 24 healthy, age-matched controls. All patients and controls had normal findings on conventional MRI. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), three eigenvalues λ1, λ2, λ3, N-acetylaspartic acid (NAA)/choline (Cho), NAA/creatinine (Cr), and Cho/Cr were measured in both temporal lobes. Patients were divided into three groups according to time after completion of radiotherapy: group 1, less than 6 months; group 2, 6-12 months; group 3, more than 12 months. Mean values for each parameter were compared using one-way analysis of variance (ANOVA). Mean FA in group 1 was significantly lower compared to group 3 and the control group (p < 0.05). Group-wise comparisons of apparent diffusion coefficient (ADC) values among all the groups were not significantly different. Eigenvalue λ1 was significantly lower in groups 1 and 3 compared to the control group (p < 0.05). NAA/Cho and NAA/Cr were significantly lower in each group compared to the control group (p < 0.01 for both). The decrease in NAA/Cho was greatest in group 1. There were no significant between-group differences regarding Cho/Cr. A combination of DTI and (1)H-MRS can be used to detect radiation-induced brain injury, in patients treated for nasopharyngeal carcinoma. Copyright Â© 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Seismically-induced soil amplification at the DOE Paducah Gaseous Diffusion Plant site
International Nuclear Information System (INIS)
Sykora, D.W.; Haynes, M.E.
1991-01-01
A site-specific earthquake site response (soil amplification) study is being conducted for the Department of Energy (DOE), Paducah Gaseous Diffusion Plant (PGDP). This study is pursuant to an upgraded Final Safety Analysis Report in accordance with requirements specified by DOE. The seismic hazard at PGDP is dominated by the New Madrid Seismic Zone. Site-specific synthetic earthquake records developed by others were applied independently to four soil columns with heights above baserock of about 325 ft. The results for the 1000-year earthquake event indicate that the site period is between 1.0 and 1.5 sec. Incident shear waves are amplified at periods of motion greater than 0.15 sec. The peak free-field horizontal acceleration, occurring at very low periods, is 0.28 g. 13 refs., 13 figs
Seismically-induced soil amplification at the DOE Paducah Gaseous Diffusion Plant Site
International Nuclear Information System (INIS)
Sykora, D.W.; Hynes, M.E.; Brock, W.R.; Hunt, R.J.; Shaffer, K.E.
1991-01-01
A site-specific earthquake site response (soil amplification) study is being conducted for the Department of Energy (DOE), Paducah Gaseous Diffusion Plant (PGDP). This study is pursuant to an upgraded Final Safety Analysis Report in accordance with requirements specified by DOE. The seismic hazard at PGDP is dominated by the New Madrid Seismic Zone. Site-specific synthetic earthquake records developed by others were applied independently to four soil columns with heights above baserock of about 325 ft. The results for the 1000-year earthquake event indicate that the site period is between 1.0 and 1.5 sec. Incident shear waves are strongly amplified at periods of motion greater than 0.3 sec. The peak free-field horizontal acceleration, occurring at very low periods, is 0.28 g
Fractional charge and anomalous commutators
International Nuclear Information System (INIS)
Frishman, Y.; Gepner, D.
1983-06-01
Non-integer charges on topological objects in the presence of fermions are further investigated. The connection with anomalous commutators is discussed. The reason for the identical results in two-dimensional solutions and four-dimensional monopoles is pointed out. (author)
Functional brain imaging to investigate the higher brain dysfunction induced by diffuse brain injury
International Nuclear Information System (INIS)
Nariai, Tadashi; Inaji, Motoki; Ohno, Kikuo; Hiura, Mikio; Ishii, Kenji; Hosoda, Chihiro
2011-01-01
Higher brain dysfunction is the major problem of patients who recover from neurotrauma the prevents them from returning to their previous social life. Many such patients do not have focal brain damage detected with morphological imaging. We focused on studying the focal brain dysfunction that can be detected only with functional imaging with positron emission tomography (PET) in relation to the score of various cognition batteries. Patients who complain of higher brain dysfunction without apparent morphological cortical damage were recruited for this study. Thirteen patients with diffuse axonal injury (DAI) or cerebral concussion was included. They underwent a PET study to image glucose metabolism by 18 F-fluorodeoxyglucose (FDG), and central benodiazepine receptor (cBZD-R) (marker of neuronal body) by 11 C-flumazenil, together with cognition measurement by WAIS-R, WMS-R, and WCST etc. PET data were compared with age matched normal controls using statistical parametric mapping (SPM)2. DAI patients had a significant decrease in glucose matabolism and cBZD-R distribution in the cingulated cortex than normal controls. Patients diagnosed with concussion because of shorter consciousness disturbance also had abnormal FDG uptake and cBZD-R distribution. Cognition test scores were variable among patients. Degree of decreased glucose metabolism and cBZD-R distribution in the dominant hemishphere corresponded well to the severity of cognitive disturbance. PET molecular imaging was useful to depict focal cortical dysfunction of neurotrauma patients even when morphological change was not apparent. This method may be promising to clarify the pathophysiology of higher brain dysfunction of patients with diffuse axonal injury or chronic traumatic encephalopathy. (author)
Drift wave vortices and anomalous transport
International Nuclear Information System (INIS)
Horton, W.
1990-01-01
Many plasma equations for drift waves and other modes possess vortex solutions, so it is important to consider the transport associated with vortex structures and their mutual interactions. Vortex structures occur when the amplitude of the fluctuation is sufficient to trap and circulate plasma around the vortex in one wave period. The vortex contribution of the diffusion of the passively convected scalar field was calculated. It was found that the field can be represented by the superposition of vortices and wave fluctuation components. For transport the computer solutions for the vortex-vortex collisions with various impact parameters while carrying along the passively convected scalar thermodynamic field were used. As the result, the inelastic collisions with b≅r 0 ≅1/k x cross-section σ(b)≅b exp(-b/r 0 )≅r 0 give the strongest transport. An example is shown in figure. As the final result, the anomalous diffusion D was derived in dimensional form. (M.T.)
Directory of Open Access Journals (Sweden)
Jaime F. Olavarria
2012-01-01
Full Text Available Callosal connections form elaborate patterns that bear close association with striate and extrastriate visual areas. Although it is known that retinal input is required for normal callosal development, there is little information regarding the period during which the retina is critically needed and whether this period correlates with the same developmental stage across species. Here we review the timing of this critical period, identified in rodents and ferrets by the effects that timed enucleations have on mature callosal connections, and compare it to other developmental milestones in these species. Subsequently, we compare these events to diffusion tensor imaging (DTI measurements of water diffusion anisotropy within developing cerebral cortex. We observed that the relationship between the timing of the critical period and the DTI-characterized developmental trajectory is strikingly similar in rodents and ferrets, which opens the possibility of using cortical DTI trajectories for predicting the critical period in species, such as humans, in which this period likely occurs prenatally. Last, we discuss the potential of utilizing DTI to distinguish normal from abnormal cerebral cortical development, both within the context of aberrant connectivity induced by early retinal deafferentation, and more generally as a potential tool for detecting abnormalities associated with neurodevelopmental disorders.
Maldonado, Sergio; Borthwick, Alistair G L
2018-02-01
We derive a two-layer depth-averaged model of sediment transport and morphological evolution for application to bedload-dominated problems. The near-bed transport region is represented by the lower (bedload) layer which has an arbitrarily constant, vanishing thickness (of approx. 10 times the sediment particle diameter), and whose average sediment concentration is free to vary. Sediment is allowed to enter the upper layer, and hence the total load may also be simulated, provided that concentrations of suspended sediment remain low. The model conforms with established theories of bedload, and is validated satisfactorily against empirical expressions for sediment transport rates and the morphodynamic experiment of a migrating mining pit by Lee et al. (1993 J. Hydraul. Eng. 119 , 64-80 (doi:10.1061/(ASCE)0733-9429(1993)119:1(64))). Investigation into the effect of a local bed gradient on bedload leads to derivation of an analytical, physically meaningful expression for morphological diffusion induced by a non-zero local bed slope. Incorporation of the proposed morphological diffusion into a conventional morphodynamic model (defined as a coupling between the shallow water equations, Exner equation and an empirical formula for bedload) improves model predictions when applied to the evolution of a mining pit, without the need either to resort to special numerical treatment of the equations or to use additional tuning parameters.
Maldonado, Sergio; Borthwick, Alistair G. L.
2018-02-01
We derive a two-layer depth-averaged model of sediment transport and morphological evolution for application to bedload-dominated problems. The near-bed transport region is represented by the lower (bedload) layer which has an arbitrarily constant, vanishing thickness (of approx. 10 times the sediment particle diameter), and whose average sediment concentration is free to vary. Sediment is allowed to enter the upper layer, and hence the total load may also be simulated, provided that concentrations of suspended sediment remain low. The model conforms with established theories of bedload, and is validated satisfactorily against empirical expressions for sediment transport rates and the morphodynamic experiment of a migrating mining pit by Lee et al. (1993 J. Hydraul. Eng. 119, 64-80 (doi:10.1061/(ASCE)0733-9429(1993)119:1(64))). Investigation into the effect of a local bed gradient on bedload leads to derivation of an analytical, physically meaningful expression for morphological diffusion induced by a non-zero local bed slope. Incorporation of the proposed morphological diffusion into a conventional morphodynamic model (defined as a coupling between the shallow water equations, Exner equation and an empirical formula for bedload) improves model predictions when applied to the evolution of a mining pit, without the need either to resort to special numerical treatment of the equations or to use additional tuning parameters.
The induced dimension reduction method applied to convection-diffusion-reaction problems
Astudillo Rengifo, R.A.; van Gijzen, M.B.
2016-01-01
Discretization of (linearized) convection-diusion-reaction problems yields
a large and sparse non symmetric linear system of equations,
Ax = b: (1)
In this work, we compare the computational behavior of the Induced Dimension
Reduction method (IDR(s)) [10], with other
Prediction of a quantum anomalous Hall state in Co-decorated silicene
Kaloni, Thaneshwor P.
2014-01-09
Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.
Prediction of a quantum anomalous Hall state in Co-decorated silicene
Kaloni, Thaneshwor P.; Schwingenschlö gl, Udo; Singh, Nirpendra
2014-01-01
Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.
Directory of Open Access Journals (Sweden)
Rupinder Singh
2017-01-01
Full Text Available Metronidazole-induced neuro-toxicity, though rare, is known. A characteristic spatial distribution of lesions in cerebellar dentate nuclei and dorsal pons is known. However, temporal progression of lesions on magnetic resonance imaging (MRI has not been described previously. We describe two such cases which presented initially with splenial hyperintesity and showed progression to characterstic lesions. Both cases improved with stoppage of metronidazole.
Lazaridou, Asimina; Astrakas, Loukas; Mintzopoulos, Dionyssios; Khanicheh, Azadeh; Singhal, Aneesh B; Moskowitz, Michael A; Rosen, Bruce; Tzika, Aria A
2013-11-01
Stroke is the third leading cause of mortality and a frequent cause of long-term adult impairment. Improved strategies to enhance motor function in individuals with chronic disability from stroke are thus required. Post‑stroke therapy may improve rehabilitation and reduce long-term disability; however, objective methods for evaluating the specific impact of rehabilitation are rare. Brain imaging studies on patients with chronic stroke have shown evidence for reorganization of areas showing functional plasticity after a stroke. In this study, we hypothesized that brain mapping using a novel magnetic resonance (MR)-compatible hand device in conjunction with state‑of‑the‑art magnetic resonance imaging (MRI) can serve as a novel biomarker for brain plasticity induced by rehabilitative motor training in patients with chronic stroke. This hypothesis is based on the premises that robotic devices, by stimulating brain plasticity, can assist in restoring movement compromised by stroke-induced pathological changes in the brain and that these changes can then be monitored by advanced MRI. We serially examined 15 healthy controls and 4 patients with chronic stroke. We employed a combination of diffusion tensor imaging (DTI) and volumetric MRI using a 3-tesla (3T) MRI system using a 12-channel Siemens Tim coil and a novel MR-compatible hand‑induced robotic device. DTI data revealed that the number of fibers and the average tract length significantly increased after 8 weeks of hand training by 110% and 64%, respectively (probotics in the molecular medicine era.
Nuclear relaxation induced by diffusion in confined media; the case of inverted micelles
International Nuclear Information System (INIS)
Llor, Antoine
1983-01-01
This work emphasizes the specificities of molecular motions in restricted media observed by NMR. The observation of proton nuclear relaxation of small water pools in AOT reversed micelles has led to separation of dipolar contributions using substitution by deuterium. The water-water contributions to relaxation are easily explained by well-known models and show that water rotational movements are, at most, five times slower than in pure water. The other contributions display a strong frequency dependence with spectrometer frequency and, in order to explain them, a specific dipolar relaxation model was developed between two particles whose movements are restricted to the surface of a sphere and in a concentric sphere respectively. This model was generalized to all cases of diffusion movements of particles in a spherical symmetry environment. In the case of AOT micelles, this model can not explain the experimental results. An elementary discussion taking into account the polar heads specificities and their interactions with water lead to a qualitative interpretation of the experimental data. (author) [fr
Segregation and diffusion of deffects induced by radiation in binary copper alloys
International Nuclear Information System (INIS)
Monteiro, W.A.
1984-01-01
Actually considerable theoretical and experimental progress has been made in establishing and in understanding the general feactures of the Radiation Induced Solute Difusion or Segregation such as its temperature, time and displacement rate dependence and the effects of some important materials factors such as the initial solute misfit. During irradiation, the local alloy compositions will change by defect flux driven, non-equilibrium segregation near sinks such as voids, external surfaces and grain boundaries and the compositional change are likely to influence a number of properties and phenomena important to Thermonuclear Reactors, as for example, Ductility, Corrosion, Stress, Corrosion Craking, Sputtering and Blistering. Our work is correlated with the 1 MeV electrons irradiations effects in Copper alloys where the alloying elements are Be, Pt, Sn. These three elements are undersized, similar and oversized relating the Copper atom radius, respectively. How starts and develops the Segregation Induced by Irradiation 'In Situ' with help of the High Voltage Electron Microscopy as technique. (Author) [pt
Magnetic effects in anomalous dispersion
International Nuclear Information System (INIS)
Blume, M.
1992-01-01
Spectacular enhancements of magnetic x-ray scattering have been predicted and observed experimentally. These effects are the result of resonant phenomena closely related to anomalous dispersion, and they are strongest at near-edge resonances. The theory of these resonances will be developed with particular attention to the symmetry properties of the scatterer. While the phenomena to be discussed concern magnetic properties the transitions are electric dipole or electric quadrupole in character and represent a subset of the usual anomalous dispersion phenomena. The polarization dependence of the scattering is also considered, and the polarization dependence for magnetic effects is related to that for charge scattering and to Templeton type anisotropic polarization phenomena. It has been found that the strongest effects occur in rare-earths and in actinides for M shell edges. In addition to the scattering properties the theory is applicable to ''forward scattering'' properties such as the Faraday effect and circular dichroism
Faraday anomalous dispersion optical tuners
Wanninger, P.; Valdez, E. C.; Shay, T. M.
1992-01-01
Common methods for frequency stabilizing diode lasers systems employ gratings, etalons, optical electric double feedback, atomic resonance, and a Faraday cell with low magnetic field. Our method, the Faraday Anomalous Dispersion Optical Transmitter (FADOT) laser locking, is much simpler than other schemes. The FADOT uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. This method is vibration insensitive, thermal expansion effects are minimal, and the system has a frequency pull in range of 443.2 GHz (9A). Our technique is based on the Faraday anomalous dispersion optical filter. This method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters. We present the first theoretical model for the FADOT and compare the calculations to our experimental results.
Random-walk diffusion and drying of porous materials
Mehrafarin, M.; Faghihi, M.
2001-12-01
Based on random-walk diffusion, a microscopic model for drying is proposed to explain the characteristic features of the drying-rate curve of porous materials. The constant drying-rate period is considered as a normal diffusion process. The transition to the falling-rate regime is attributed to the fractal nature of porous materials which results in crossover to anomalous diffusion.
Anomalous photon-assisted tunneling in graphene
International Nuclear Information System (INIS)
Iurov, Andrii; Gumbs, Godfrey; Roslyak, Oleksiy; Huang, Danhong
2012-01-01
We investigated the transmission of Dirac electrons through a potential barrier in the presence of circularly polarized light. An anomalous photon-assisted enhanced transmission is predicted and explained. It is demonstrated that the perfect transmission for nearly head-on collision in infinite graphene is suppressed in gapped dressed states of electrons, which is further accompanied by a shift of peaks as a function of the incident angle away from head-on collision. In addition, the perfect transmission is partially suppressed by a photon-induced gap in illuminated graphene. After the effect of rough edges of the potential barrier or impurity scattering is included, the perfect transmission with no potential barrier becomes completely suppressed and the energy range for the photon-assisted transmission is reduced at the same time. (paper)
Anomalous normal mode oscillations in semiconductor microcavities
Energy Technology Data Exchange (ETDEWEB)
Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)
1997-04-01
Semiconductor microcavities as a composite exciton-cavity system can be characterized by two normal modes. Under an impulsive excitation by a short laser pulse, optical polarizations associated with the two normal modes have a {pi} phase difference. The total induced optical polarization is then expected to exhibit a sin{sup 2}({Omega}t)-like oscillation where 2{Omega} is the normal mode splitting, reflecting a coherent energy exchange between the exciton and cavity. In this paper the authors present experimental studies of normal mode oscillations using three-pulse transient four wave mixing (FWM). The result reveals surprisingly that when the cavity is tuned far below the exciton resonance, normal mode oscillation in the polarization is cos{sup 2}({Omega}t)-like, in contrast to what is expected form the simple normal mode model. This anomalous normal mode oscillation reflects the important role of virtual excitation of electronic states in semiconductor microcavities.
Schwinger Model Mass Anomalous Dimension
Keegan, Liam
2016-06-20
The mass anomalous dimension for several gauge theories with an infrared fixed point has recently been determined using the mode number of the Dirac operator. In order to better understand the sources of systematic error in this method, we apply it to a simpler model, the massive Schwinger model with two flavours of fermions, where analytical results are available for comparison with the lattice data.
Faraday anomalous dispersion optical filters
Shay, T. M.; Yin, B.; Alvarez, L. S.
1993-01-01
The effect of Faraday anomalous dispersion optical filters on infrared and blue transitions of some alkali atoms is calculated. A composite system is designed to further increase the background noise rejection. The measured results of the solar background rejection and image quality through the filter are presented. The results show that the filter may provide high transmission and high background noise rejection with excellent image quality.
International Nuclear Information System (INIS)
Hua Chiaho; Merchant, Thomas E.; Gajjar, Amar; Broniscer, Alberto; Zhang, Yong; Li Yimei; Glenn, George R.; Kun, Larry E.; Ogg, Robert J.
2012-01-01
Purpose: To characterize therapy-induced changes in normal-appearing brainstems of childhood brain tumor patients by serial diffusion tensor imaging (DTI). Methods and Materials: We analyzed 109 DTI studies from 20 brain tumor patients, aged 4 to 23 years, with normal-appearing brainstems included in the treatment fields. Those with medulloblastomas, supratentorial primitive neuroectodermal tumors, and atypical teratoid rhabdoid tumors (n = 10) received postoperative craniospinal irradiation (23.4–39.6 Gy) and a cumulative dose of 55.8 Gy to the primary site, followed by four cycles of high-dose chemotherapy. Patients with high-grade gliomas (n = 10) received erlotinib during and after irradiation (54–59.4 Gy). Parametric maps of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were computed and spatially registered to three-dimensional radiation dose data. Volumes of interest included corticospinal tracts, medial lemnisci, and the pons. Serving as an age-related benchmark for comparison, 37 DTI studies from 20 healthy volunteers, aged 6 to 25 years, were included in the analysis. Results: The median DTI follow-up time was 3.5 years (range, 1.6–5.0 years). The median mean dose to the pons was 56 Gy (range, 7–59 Gy). Three patterns were seen in longitudinal FA and apparent diffusion coefficient changes: (1) a stable or normal developing time trend, (2) initial deviation from normal with subsequent recovery, and (3) progressive deviation without evidence of complete recovery. The maximal decline in FA often occurred 1.5 to 3.5 years after the start of radiation therapy. A full recovery time trend could be observed within 4 years. Patients with incomplete recovery often had a larger decline in FA within the first year. Radiation dose alone did not predict long-term recovery patterns. Conclusions: Variations existed among individual patients after therapy in longitudinal evolution of brainstem white matter injury and recovery. Early response
Oscillatory variation of anomalous diffusion in pendulum systems
Indian Academy of Sciences (India)
driven and parametrically-driven pendulum systems are presented. When the frequency of the periodic driving force is varied, the exponent μ, which is the rate of divergence of the mean square displacement with time, is found to vary in an ...
Universality of anomalous diffusion in extremely disordered systems
DEFF Research Database (Denmark)
Dyre, Jeppe; Jacobsen, Jacob M.
1996-01-01
The universal time-dependence of the mean-square displacement for motion in a random energy landscape with equal minima is evaluated analytically and numerically in the percolation path approximation (PPA), which was recently shown by extensive computer simulations in two and three dimensions [Dy...
Lin, Neil Y. C.
2013-12-01
Using high-speed confocal microscopy, we measure the particle positions in a colloidal suspension under large-amplitude oscillatory shear. Using the particle positions, we quantify the in situ anisotropy of the pair-correlation function, a measure of the Brownian stress. From these data we find two distinct types of responses as the system crosses over from equilibrium to far-from-equilibrium states. The first is a nonlinear amplitude saturation that arises from shear-induced advection, while the second is a linear frequency saturation due to competition between suspension relaxation and shear rate. In spite of their different underlying mechanisms, we show that all the data can be scaled onto a master curve that spans the equilibrium and far-from-equilibrium regimes, linking small-amplitude oscillatory to continuous shear. This observation illustrates a colloidal analog of the Cox-Merz rule and its microscopic underpinning. Brownian dynamics simulations show that interparticle interactions are sufficient for generating both experimentally observed saturations. © 2013 American Physical Society.
Lin, Neil Y. C.; Goyal, Sushmit; Cheng, Xiang; Zia, Roseanna N.; Escobedo, Fernando A.; Cohen, Itai
2013-01-01
Using high-speed confocal microscopy, we measure the particle positions in a colloidal suspension under large-amplitude oscillatory shear. Using the particle positions, we quantify the in situ anisotropy of the pair-correlation function, a measure of the Brownian stress. From these data we find two distinct types of responses as the system crosses over from equilibrium to far-from-equilibrium states. The first is a nonlinear amplitude saturation that arises from shear-induced advection, while the second is a linear frequency saturation due to competition between suspension relaxation and shear rate. In spite of their different underlying mechanisms, we show that all the data can be scaled onto a master curve that spans the equilibrium and far-from-equilibrium regimes, linking small-amplitude oscillatory to continuous shear. This observation illustrates a colloidal analog of the Cox-Merz rule and its microscopic underpinning. Brownian dynamics simulations show that interparticle interactions are sufficient for generating both experimentally observed saturations. © 2013 American Physical Society.
Langlands, T A M; Henry, B I; Wearne, S L
2009-12-01
We introduce fractional Nernst-Planck equations and derive fractional cable equations as macroscopic models for electrodiffusion of ions in nerve cells when molecular diffusion is anomalous subdiffusion due to binding, crowding or trapping. The anomalous subdiffusion is modelled by replacing diffusion constants with time dependent operators parameterized by fractional order exponents. Solutions are obtained as functions of the scaling parameters for infinite cables and semi-infinite cables with instantaneous current injections. Voltage attenuation along dendrites in response to alpha function synaptic inputs is computed. Action potential firing rates are also derived based on simple integrate and fire versions of the models. Our results show that electrotonic properties and firing rates of nerve cells are altered by anomalous subdiffusion in these models. We have suggested electrophysiological experiments to calibrate and validate the models.
International Nuclear Information System (INIS)
Pedersen, Torje V.; Olsen, Dag R.; Skretting, Arne
1997-01-01
A method has been developed to determine the diffusion coefficients of ferric ions in ferrous sulphate doped gels. A radiation induced edge was created in the gel, and two spin-echo sequences were used to acquire a pair of images of the gel at different points of time. For each of these image pairs, a longitudinal relaxation rate image was derived. From profiles through these images, the standard deviations of the Gaussian functions that characterize diffusion were determined. These data provided the basis for the determination of the ferric diffusion coefficients by two different methods. Simulations indicate that the use of single spin-echo images in this procedure may in some cases lead to a significant underestimation of the diffusion coefficient. The technique was applied to different agarose and gelatine gels that were prepared, irradiated and imaged simultaneously. The results indicate that the diffusion coefficient is lower in a gelatine gel than in an agarose gel. Addition of xylenol orange to a gelatine gel lowers the diffusion coefficient from 1.45 to 0.81 mm 2 h -1 , at the cost of significantly lower R 1 sensitivity. The addition of benzoic acid to the latter gel did not increase the R 1 sensitivity. (author) OK
Anomalous low-temperature desorption from preirradiated rare gas solids
International Nuclear Information System (INIS)
Savchenko, E.V.; Gumenchuk, G.B.; Yurtaeva, E.M.; Belov, A.G.; Khyzhniy, I.V.; Frankowski, M.; Beyer, M.K.; Smith-Gicklhorn, A.M.; Ponomaryov, A.N.; Bondybey, V.E.
2005-01-01
The role for the exciton-induced defects in the stimulation of anomalous low-temperature desorption of the own lattice atoms from solid Ar and Ne preirradiated by an electron beam is studied. The free electrons from shallow traps-structural defects-was monitored by the measurements of a yield of the thermally induced exoelectron emission (TSEE). The reaction of recombination of self-trapped holes with electrons is considered as a source of energy needed for the desorption of atoms from the surface of preirradiated solids. A key part of the exciton-induced defects in the phenomenon observed is demonstrated
International Nuclear Information System (INIS)
Uematsu, Masashi; Yanagawa, Fumihiko
1988-01-01
The Si diffusion in Si-implanted GaAs/Al 0.5 Ga 0.5 As superlattices intermixed in the disrodering process induced by rapid thermal annealing (RTA), is investigated by means of secondary ion mass spectroscopy (SIMS). The SIMS profiles indicate that no fast Si diffusion occurs during the disordering, and the disordering occurs when the Si concentration exceeds 1 x 10 19 cm -3 , which is about three times larger than the threshold value for the disordering by furnace annealing (FA). The number of Si atoms which are allowed to pass through the heterointerface is considered to be essential for disordering. (author)
Wang, Xuezhen; Lai, Jiancheng; Song, Yang; Li, Zhenhua
2018-05-01
It is generally recognized that circularly polarized light is preferentially maintained over linearly polarized light in turbid medium with Mie scatterers. However, in this work, the anomalous depolarization anisotropy is reported in the backscattering area near the point of illumination. Both experimental and Monte Carlo simulations show preferential retention of linear polarization states compared to circular polarization states in a specific backscattering area. Further analysis indicates that the anomalous depolarization behavior in the specific area is induced by lateral scattering events, which own low circular polarization memory. In addition, it is also found that the size of the anomalous depolarization area is related to the transport mean free path of the turbid medium.
Anomalous Nernst Effects of [CoSiB/Pt] Multilayer Films
Kelekci, O.; Lee, H. N.; Kim, T. W.; Noh, H.
2013-01-01
We report a measurement for the anomalous Nernst effects induced by a temperature gradient in [CoSiB/Pt] multilayer films with perpendicular magnetic anisotropy. The Nernst voltage shows a characteristic hysteresis which reflects the magnetization of the film as in the case of the anomalous Hall effects. With a local heating geometry, we also measure the dependence of the anomalous Nernst voltage on the distance d from the heating element. It is roughly proportional to 1/d^1.3, which can be c...
Anomalous magnetic torque in the heavy-fermion superconductor UBe13
International Nuclear Information System (INIS)
Schmiedeshoff, G.M.; Fisk, Z.; Smith, J.L.
1994-01-01
Measurements of the magnetic torque acting upon a single crystal of the heavy-fermion superconductor UBe 13 have been made at temperatures from 0.5 K to 30.0 K and in magnetic fields to 23 T using a capacitive magnetometer. We find that a large, anomalous contribution to the magnetic torque appears in at low temperatures and in high fields. The anomalous torque coexists with the superconducting state at low temperature. We propose that the anomalous torque reflects the existence of a field-induced magnetic phase transition. (orig.)
Anomalous U(1) as a mediator of Supersymmetry Breaking
Dvali, Gia; Dvali, Gia; Pomarol, Alex
1996-01-01
We point out that an anomalous gauge U(1) symmetry is a natural candida= te for being the mediator and messenger of supersymmetry breaking. It facilitate= s dynamical supersymmetry breaking even in the flat limit. Soft masses are induced by both gravity and the U(1) gauge interactions giving an unusual= mass hierarchy in the sparticle spectrum which suppresses flavor violations. T= his scenario does not suffer from the Polonyi problem.
Anomalous transport due to shear-Alfven waves
International Nuclear Information System (INIS)
Lee, W.W.; Chance, M.S.; Okuda, H.
1980-10-01
The behavior of shear-Alfven eigenmodes and the accompanied anomalous transport have been investigated. In the particle simulation, equilibrium thermal fluctuations associated with the eigenmodes have been observed to nullify the zeroth-order shear near the rational surface through the induced second-order eddy current, and, in turn, give rise to the formation of magnetic islands which cause rapid electron energy transport in the region. The theoretical verification of the observed behavior is discussed
International Nuclear Information System (INIS)
Yamaguchi, M.; Takamoto, T.; Taylor, S.J.; Walters, R.J.; Summers, G.P.; Flood, D.J.; Ohmori, M.
1997-01-01
The damage to diffused-junction n + -p InP solar cells induced by electron and proton irradiations over a wide range of energy from 0.5 to 3 MeV and 0.015 to 20 MeV, respectively, has been examined. The experimental electron and proton damage coefficients have been analyzed in terms of displacement damage dose, which is the product of the particle fluence and the calculated nonionizing energy loss [G. P. Summers, E. A. Burke, R. Shapiro, S. R. Messenger, and R. J. Walters, IEEE Trans. Nucl. Sci. 40, 1300 (1993).] Degradation of InP cells due to irradiation with electrons and protons with energies of more than 0.5 MeV show a single curve as a function of displacement damage dose. Based on the deep-level transient spectroscopy analysis, damage equivalence between electron and proton irradiation is discussed. InP solar cells are confirmed to be substantially more radiation resistant than Si and GaAs-on-Ge cells. copyright 1997 American Institute of Physics
International Nuclear Information System (INIS)
Dungey, J.W.
1984-01-01
The authors want to talk about future work, but first he will reply to Stan Cowley's comment on his naivety in believing in the whole story to 99% confidence in '65, when he knew about Fairfield's results. Does it matter whether you make the right judgment about theories? Yes, it does, particularly for experimentalists perhaps, but also for theorists. The work you do later depends on the judgment you've made on previous work. People have wasted a lot of time developing on insecure or even wrong foundations. Now for future work. One mild surprise the authors have had is that they haven't heard more about diffusion, in two contexts. Gordon Rostoker is yet to come and he may talk about particles getting into the magnetosphere by diffusion. Lots of noise is observed and so diffusion must happen. If time had not been short, the authors were planning to discuss in a handwaving way what sort of diffusion mechanisms one might consider. The other aspect of diffusion he was going to talk about is at the other end of things and is velocity diffusion, which is involved in anomalous resistivity
International Nuclear Information System (INIS)
Michaud, Georges; Montmerle, Thierry
1977-01-01
This paper is dealing with the origin of the elements in the universe. The scheme of nucleosynthesis is kept to explain the stellar generation of helium, carbon, etc... from the initial hydrogen; but a nonlinear theory is then elaborated to account for the anomalous abundances which were observed. The chemical elements would diffuse throughout the outer layers of a star under the action of the opposite forces of gravitation and radiation. This theory, with completing the nucleosynthesis, would contribute to give a consistent scheme of the elemental origin and abundances [fr
Oxygen-induced high diffusion rate of magnesium dopants in GaN/AlGaN based UV LED heterostructures.
Michałowski, Paweł Piotr; Złotnik, Sebastian; Sitek, Jakub; Rosiński, Krzysztof; Rudziński, Mariusz
2018-05-23
Further development of GaN/AlGaN based optoelectronic devices requires optimization of the p-type material growth process. In particular, uncontrolled diffusion of Mg dopants may decrease the performance of a device. Thus it is meaningful to study the behavior of Mg and the origins of its diffusion in detail. In this work we have employed secondary ion mass spectrometry to study the diffusion of magnesium in GaN/AlGaN structures. We show that magnesium has a strong tendency to form Mg-H complexes which immobilize Mg atoms and restrain their diffusion. However, these complexes are not present in samples post-growth annealed in an oxygen atmosphere or Al-rich AlGaN structures which naturally have a high oxygen concentration. In these samples, more Mg atoms are free to diffuse and thus the average diffusion length is considerably larger than for a sample annealed in an inert atmosphere.
Anomalous Hall effect in polycrystalline Ni films
Guo, Zaibing
2012-02-01
We systematically studied the anomalous Hall effect in a series of polycrystalline Ni films with thickness ranging from 4 to 200 nm. It is found that both the longitudinal and anomalous Hall resistivity increased greatly as film thickness decreased. This enhancement should be related to the surface scattering. In the ultrathin films (46 nm thick), weak localization corrections to anomalous Hall conductivity were studied. The granular model, taking into account the dominated intergranular tunneling, has been employed to explain this phenomenon, which can explain the weak dependence of anomalous Hall resistivity on longitudinal resistivity as well. © 2011 Elsevier Ltd. All rights reserved.
Anomalous properties of technetium clusters
International Nuclear Information System (INIS)
Kryuchkov, S.V.
1985-01-01
On the basis of critical evaluation of literature data in the field of chemistry of technetium cluster compounds with ligands of a weak field a conclusion is made on specific, ''anomalous'' properties of technetium cluster complexes which consist in an increased ability of the given element to the formation of a series of binuclear and multinuclear clusters, similar in composition and structure and easily transforming in each other. The majority of technetium clusters unlike similar compounds of other elements are paramagnetic with one unpaired electron on ''metallic'' MO of loosening type. All theoretical conceptions known today on the electronic structure of technetium clusters are considered. It is pointed out, that the best results in the explanation of ''anomalous'' properties of technetium clusters can be obtained in the framework of nonempirical methods of self-consistent field taking into account configuration interactions. It is also shown, that certain properties of technetium clusters can be explained on the basis of qualitative model of Coulomb repulsion of metal atoms in clusters. The conclusion is made, that technetium position in the Periodic table, as well as recently detected technetium property to the decrease of effective charge on its atoms during M-M bond formation promote a high ability of the element to cluster formation both with weak field ligands and with strong field one
Kinetic studies of anomalous transport
International Nuclear Information System (INIS)
Tang, W.M.
1990-11-01
Progress in achieving a physics-based understanding of anomalous transport in toroidal systems has come in large part from investigations based on the proposition that low frequency electrostatic microinstabilities are dominant in the bulk (''confinement'') region of these plasmas. Although the presence here of drift-type modes dependent on trapped particle and ion temperature gradient driven effects appears to be consistent with a number of important observed confinement trends, conventional estimates for these instabilities cannot account for the strong current (I p ) and /or q-scaling frequently found in empirically deduced global energy confinement times for auxiliary-heated discharges. The present paper deals with both linear and nonlinear physics features, ignored in simpler estimates, which could introduce an appreciable local dependence on current. It is also pointed out that while the thermal flux characteristics of drift modes have justifiably been the focus of experimental studies assessing their relevance, other transport properties associated with these microinstabilities should additionally be examined. Accordingly, the present paper provides estimates and discusses the significance of anomalous energy exchange between ions and electrons when fluctuations are present. 19 refs., 3 figs
Anomalous transport in toroidal plasmas
International Nuclear Information System (INIS)
Punjabi, A.
1989-12-01
When the magnetic moment of particle is conserved, there are three mechanisms which cause anomalous transport. These are: variation of magnetic field strength in flux surface, variation of electrostatic potential in flux surface, and destruction of flux surface. The anomalous transport of different groups of particles resulting from each of these mechanisms is different. This fact can be exploited to determine the cause of transport operative in an experimental situation. This approach can give far more information on the transport than the standard confinement time measurements. To implement this approach, we have developed Monte Carlo codes for toroidal geometries. The equations of motion are developed in a set of non-canonical, practical Boozer co-ordinates by means of Jacobian transformations of the particle drift Hamiltonian equations of motion. Effects of collisions are included by appropriate stochastic changes in the constants of motion. Effects of the loop voltage on particle motions are also included. We plan to apply our method to study two problems: the problem of the hot electron tail observed in edge region of ZT-40, and the energy confinement time in TOKAPOLE II. For the ZT-40 problem three situations will be considered: a single mode in the core, a stochastic region that covers half the minor radius, a stochastic region that covers the entire plasma. A turbulent spectrum of perturbations based on the experimental data of TOKAPOLE II will be developed. This will be used to simulate electron transport resulting from ideal instabilities and resistive instabilities in TOKAPOLE II
Anomalous transport in toroidal plasmas
International Nuclear Information System (INIS)
Punjabi, A.
1991-01-01
We have developed a Monte Carlo method to estimate the transport of different groups of particles for plasmas in toroidal geometries. This method can determine the important transport mechanisms driving the anomalous transport by comparing the numerical results with the experimental data. The important groups of particles whose transport can be estimated by this method include runaway electrons, thermal electrons, both passing and trapped diagnostic beam ions etc. The three basic mechanisms driving the anomalous transport are: spatial variation of magnetic field strength, spatial variation of electrostatic potential within the flux surfaces, and the loss of flux surfaces. The equation of motion are obtained from the drift hamiltonian. The equations of motion are developed in the canonical and in the non-canonical, practical co-ordinates as well. The effects of collisions are represented by appropriate stochastic changes in the constants of motion at each time-step. Here we present the results of application of this method to three cases: superathermal alphas in the rippled field of tokamaks, motion in the magnetic turbulence of takapole II, and transport in the stochastic fields of ZT40. This work is supported by DOE OFE and ORAU HBCU program
Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong
2004-04-01
Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.
Low Temperature Diffusion Transformations in Fe-Ni-Ti Alloys During Deformation and Irradiation
Sagaradze, Victor; Shabashov, Valery; Kataeva, Natalya; Kozlov, Kirill; Arbuzov, Vadim; Danilov, Sergey; Ustyugov, Yury
2018-03-01
The deformation-induced dissolution of Ni3Ti intermetallics in the matrix of austenitic alloys of Fe-36Ni-3Ti type was revealed in the course of their cascade-forming neutron irradiation and cold deformation at low temperatures via employment of Mössbauer method. The anomalous deformation-related dissolution of the intermetallics has been explained by the migration of deformation-induced interstitial atoms from the particles into a matrix in the stress field of moving dislocations. When rising the deformation temperature, this process is substituted for by the intermetallics precipitation accelerated by point defects. A calculation of diffusion processes has shown the possibility of the realization of the low-temperature diffusion of interstitial atoms in configurations of the crowdions and dumbbell pairs at 77-173 K. The existence of interstitial atoms in the Fe-36Ni alloy irradiated by electrons or deformed at 77 K was substantiated in the experiments of the electrical resistivity measurements.
Neoclassical and anomalous transport in toroidal plasmas with drift-ordered turbulence
International Nuclear Information System (INIS)
Sugama, H.; Horton, W.
1996-01-01
Neoclassical and anomalous transport fluxes are determined for axisymmetric toroidal plasmas with weak electromagnetic drift wave fluctuations. The neoclassical and anomalous fluxes are defined based on the ensemble-averaged kinetic equation with the statistically averaged nonlinear wave-particle interactions. The anomalous forces derived from that quasilinear term induce the anomalous particle and heat fluxes. For the microscale fluctuations k perpendicular ρ i ∼ 1 the parallel neoclassical fluxes remain invariant. For mesoscale fluctuations the mixing length fluctuation level with broken symmetry from (weak) shear flows the neoclassical banana-plateau fluxes are affected by the fluctuations through the parallel anomalous forces and the modified parallel viscosities. The entropy production rate due to the anomalous transport processes is formulated and used to identify conjugate pairs of the anomalous fluxes and forces, which are connected by the matrix with the Onsager symmetry. The proof of the Onsager symmetry is carried out by splitting the response function up into the even and odd parts under the (t, B) → (-t,-B) transformation and using the self-adjointness of the linearized Landau collision operator and the quasilinear formalism. An explicit calculation of the symmetric transport coefficients is possible when the Krook collision model replaces the Landau collision operator. The importance of low aspect ratio tokamaks and helical systems for experimental investigations of the Onsager symmetries is emphasized
Anomalous behaviors during infiltration into heterogeneous porous media
Aarão Reis, F. D. A.; Bolster, D.; Voller, V. R.
2018-03-01
Flow and transport in heterogeneous porous media often exhibit anomalous behavior. A physical analog example is the uni-directional infiltration of a viscous liquid into a horizontal oriented Hele-Shaw cell containing through thickness flow obstacles; a system designed to mimic a gravel/sand medium with impervious inclusions. When there are no obstacles present or the obstacles form a multi-repeating pattern, the change of the length of infiltration F with time t tends to follow a Fickian like scaling, F ∼t1/2 . In the presence of obstacle fields laid out as Sierpinski carpet fractals, infiltration is anomalous, i.e., F ∼ tn, n ≠ 1/2. Here, we study infiltration into such Hele-Shaw cells. First we investigate infiltration into a square cell containing one fractal carpet and make the observation that it is possible to generate both sub (n 1/2) diffusive behaviors within identical heterogeneity configurations. We show that this can be explained in terms of a scaling analysis developed from results of random-walk simulations in fractal obstacles; a result indicating that the nature of the domain boundary controls the exponent n of the resulting anomalous transport. Further, we investigate infiltration into a rectangular cell containing several repeats of a given Sierpinski carpet. At very early times, before the liquid encounters any obstacles, the infiltration is Fickian. When the liquid encounters the first (smallest scale) obstacle the infiltration sharply transitions to sub-diffusive. Subsequently, around the time where the liquid has sampled all of the heterogeneity length scales in the system, there is a rapid transition back to Fickian behavior. An explanation for this second transition is obtained by developing a simplified infiltration model based on the definition of a representative averaged hydraulic conductivity.
Anomalous osmosis resulting from preferential absorption
Staverman, A.J.; Kruissink, C.A.; Pals, D.T.F.
1965-01-01
An explanation of the anomalous osmosis described in the preceding paper is given in terms of friction coefficients in the glass membrane. It is shown that anomalous osmosis may be expected when the friction coefficients are constant and positive provided that the membrane absorbs solute strongly
Transport phenomena in sharply contrasting media with a diffusion barrier
International Nuclear Information System (INIS)
Dvoretskaya, O A; Kondratenko, P S
2011-01-01
Using the advection–diffusion equation, we analytically study contaminant transport in a sharply contrasting medium with a diffusion barrier due to localization of a contaminant source in a low-permeability medium. Anomalous diffusion behavior and a crossover between different transport regimes are observed. The diffusion barrier results in exponential attenuation of the source power, retardation of the contaminant plume growth and modification of the concentration distribution at large distances. (paper)
GRAVITATIONAL ENCOUNTERS AND THE EVOLUTION OF GALACTIC NUCLEI. III. ANOMALOUS RELAXATION
Energy Technology Data Exchange (ETDEWEB)
Merritt, David [Department of Physics and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States)
2015-09-01
This paper is the third in a series presenting the results of direct numerical integrations of the Fokker–Planck equation for stars orbiting a supermassive black hole (SBH) at the center of a galaxy. The algorithm of Paper II included diffusion coefficients that described the effects of random (“classical”) and correlated (“resonant”) relaxation. In this paper, the diffusion coefficients of Paper II have been generalized to account for the effects of “anomalous relaxation,” the qualitatively different way in which eccentric orbits evolve in the regime of rapid relativistic precession. Two functional forms for the anomalous diffusion coefficients are investigated, based on power-law or exponential modifications of the resonant diffusion coefficients. The parameters defining the modified coefficients are first constrained by comparing the results of Fokker–Planck integrations with previously published N-body integrations. Steady-state solutions are then obtained via the Fokker–Planck equation for models with properties similar to those of the Milky Way nucleus. Inclusion of anomalous relaxation leads to the formation of less prominent cores than in the case of resonant relaxation alone, due to the lengthening of diffusion timescales for eccentric orbits. Steady-state capture rates of stars by the SBH are found to always be less than capture rates in the presence of resonant relaxation alone.
GRAVITATIONAL ENCOUNTERS AND THE EVOLUTION OF GALACTIC NUCLEI. III. ANOMALOUS RELAXATION
International Nuclear Information System (INIS)
Merritt, David
2015-01-01
This paper is the third in a series presenting the results of direct numerical integrations of the Fokker–Planck equation for stars orbiting a supermassive black hole (SBH) at the center of a galaxy. The algorithm of Paper II included diffusion coefficients that described the effects of random (“classical”) and correlated (“resonant”) relaxation. In this paper, the diffusion coefficients of Paper II have been generalized to account for the effects of “anomalous relaxation,” the qualitatively different way in which eccentric orbits evolve in the regime of rapid relativistic precession. Two functional forms for the anomalous diffusion coefficients are investigated, based on power-law or exponential modifications of the resonant diffusion coefficients. The parameters defining the modified coefficients are first constrained by comparing the results of Fokker–Planck integrations with previously published N-body integrations. Steady-state solutions are then obtained via the Fokker–Planck equation for models with properties similar to those of the Milky Way nucleus. Inclusion of anomalous relaxation leads to the formation of less prominent cores than in the case of resonant relaxation alone, due to the lengthening of diffusion timescales for eccentric orbits. Steady-state capture rates of stars by the SBH are found to always be less than capture rates in the presence of resonant relaxation alone
Muon spin rotation studies of defect states in solids: the story of anomalous muonium
International Nuclear Information System (INIS)
Estle, T.L.
1983-01-01
Muon spin rotation (μSR) is a powerful technique to study magnetic phenomena, light interstitial diffusion, and hydrogenic chemistry. However it has been applied in several other areas of science where its applicability was not immediately apparent. One of these is the study of an unusual muonic defect, anomalous muonium, produced when μ + stops in semiconducting crystals. The study of anomalous muonium and the process of inferring its structure are described. For this defect, μSR has learned far more than have efforts to study the analogous hydrogenic center
International Nuclear Information System (INIS)
Maslov, V.I.; Barchuk, S.V.; Lapshin, V.I.; Volkov, E.D.; Melentsov, Yu.V.
2006-01-01
It is shown, that at development of instability due to a radial gradient of density in the crossed electric and magnetic fields in nuclear fusion installations ordering convective cells can be excited. It provides anomalous particle transport. The spatial structures of these convective cells have been constructed. The radial dimensions of these convective cells depend on their amplitudes and on a radial gradient of density. The convective-diffusion equation for radial dynamics of the electrons has been derived. At the certain value of the universal controlling parameter, the convective cell excitation and the anomalous radial transport are suppressed. (author)
Anomalous transport in mirror systems
International Nuclear Information System (INIS)
Post, R.F.
1979-01-01
As now being explored for fusion applications confinement systems based on the mirror principle embody two kinds of plasma regimes. These two regimes are: (a) high-beta plasmas, stabilized against MHD and other low frequency plasma instabilities by magnetic-well fields, but characterized by non-Maxwellian ion distributions; (b) near-Maxwellian plasmas, confined electrostatically (as in the tandem mirror) or in a field-reversed region within the mirror cell. Common to both situations are the questions of anomalous transport owing to high frequency instabilities in the non-maxwellian portions of the plasmas. This report will summarize the status of theory and of experimental data bearing on these questions, with particular reference to the high temperature regimes of interest for fusion power
Dinotor model for anomalous nuclei
International Nuclear Information System (INIS)
Castillejo, L.; Goldhaber, A.S.; Jackson, A.D.; Johnson, M.B.
1986-01-01
The simplest version of the MIT bag model implies the existence of metastable toroidal bags, with large radius proportional to the enclosed baryon number, and small radius comparable to that of an ordinary nucleon (we refer to those toroidal bags as dinotors). Considerations of various possible instabilities, and of the effects of quark interactions through intermediate gluons, suggest that the metastability is still valid when the model is treated more realistically. These results might provide an explanation for reports of anomalously large interaction cross sections of secondary fragments (''anomalons'') observed in visual track detectors. However, it appears that the most likely characteristics of toroidal bags would not be compatible with those of anomalons, and would not be as easy to detect in emulsions. copyright 1986 Academic Press, Inc
Anomalous Lorentz and CPT violation
Klinkhamer, F. R.
2018-01-01
If there exists Lorentz and CPT violation in nature, then it is crucial to discover and understand the underlying mechanism. In this contribution, we discuss one such mechanism which relies on four-dimensional chiral gauge theories defined over a spacetime manifold with topology ℛ3 × S 1 and periodic spin structure for the compact dimension. It can be shown that the effective gauge-field action contains a local Chern-Simons-like term which violates Lorentz and CPT invariance. For arbitrary Abelian U(1) gauge fields with trivial holonomies in the compact direction, this anomalous Lorentz and CPT violation has recently been established perturbatively with a Pauli-Villars-type regularization and nonperturbatively with a lattice regularization based on Ginsparg-Wilson fermions.
Yin, Deshun; Qu, Pengfei
2018-02-01
Protein lateral diffusion is considered anomalous in the plasma membrane. And this diffusion is related to membrane microstructure. In order to better describe the property of protein lateral diffusion and find out the inner relationship between protein lateral diffusion and membrane microstructure, this article applies variable-order fractional mean square displacement (f-MSD) function for characterizing the anomalous diffusion. It is found that the variable order can reflect the evolution of diffusion ability. The results of numerical simulation demonstrate variable-order f-MSD function can predict the tendency of anomalous diffusion during the process of confined diffusion. It is also noted that protein lateral diffusion ability during the processes of confined and hop diffusion can be split into three parts. In addition, the comparative analyses reveal that the variable order is related to the confinement-domain size and microstructure of compartment boundary too.
International Nuclear Information System (INIS)
Chapman, Christopher H.; Nagesh, Vijaya; Sundgren, Pia C.; Buchtel, Henry; Chenevert, Thomas L.; Junck, Larry; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue
2012-01-01
Purpose: To determine whether early assessment of cerebral white matter degradation can predict late delayed cognitive decline after radiotherapy (RT). Methods and Materials: Ten patients undergoing conformal fractionated brain RT participated in a prospective diffusion tensor magnetic resonance imaging study. Magnetic resonance imaging studies were acquired before RT, at 3 and 6 weeks during RT, and 10, 30, and 78 weeks after starting RT. The diffusivity variables in the parahippocampal cingulum bundle and temporal lobe white matter were computed. A quality-of-life survey and neurocognitive function tests were administered before and after RT at the magnetic resonance imaging follow-up visits. Results: In both structures, longitudinal diffusivity (λ ‖ ) decreased and perpendicular diffusivity (λ ⊥ ) increased after RT, with early changes correlating to later changes (p ⊥ at 3 weeks, and patients with >50% of cingula volume receiving >12 Gy had a greater increase in λ ⊥ at 3 and 6 weeks (p ‖ (30 weeks, p ‖ changes predicted for post-RT changes in verbal recall scores (3 and 6 weeks, p < .05). The neurocognitive test scores correlated significantly with the quality-of-life survey results. Conclusions: The correlation between early diffusivity changes in the parahippocampal cingulum and the late decline in verbal recall suggests that diffusion tensor imaging might be useful as a biomarker for predicting late delayed cognitive decline.
Energy Technology Data Exchange (ETDEWEB)
Masuda, Jun; Fukase, Yasushi [Toshiba Machine Co., Ltd, Ooka 2068-3, Numazu-Shi, Shizuoka-Ken, 410-8510 (Japan); Yan Jiwang; Zhou Tianfeng; Kuriyagawa, Tsunemoto, E-mail: yanjw@pm.mech.tohoku.ac.jp [Department of Mechanical Systems and Design, Graduate School of Engineering, Tohoku University, Aoba 6-6-01, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)
2011-06-01
In a glass moulding press (GMP) for refractive/diffractive hybrid lenses, to improve the service life of nickel-phosphorus (Ni-P) plated moulds, it is necessary to control the diffusion of constituent elements from the mould into the release agent coating. In this study, diffusion phenomena of constituents of Ni-P plating are investigated for two types of release agent coatings, iridium-platinum (Ir-Pt) and iridium-rhenium (Ir-Re), by cross-sectional observation, compositional analysis and stress measurements. The results show that Ni atoms in the plating layer flow from regions of compressive stress to regions of tensile stress. In the case of the Ir-Pt coated mould, the diffusion of Ni is promoted from the grain boundaries between the Ni and Ni{sub 3}P phases in the plating towards the surface of the Ir-Pt coating. However, in the Ir-Re coated mould, the diffusion of Ni is suppressed because the diffusion coefficient of Ni in the Ir-Re alloy is smaller than that in the Ir-Pt alloy, although the stress state is similar in both cases. By controlling the diffusion of Ni atoms, the use of Ir-Re alloy as a release agent coating for Ni-P plated moulds is expected to lead to a high degree of durability.
Symmetry properties of fractional diffusion equations
Energy Technology Data Exchange (ETDEWEB)
Gazizov, R K; Kasatkin, A A; Lukashchuk, S Yu [Ufa State Aviation Technical University, Karl Marx strausse 12, Ufa (Russian Federation)], E-mail: gazizov@mail.rb.ru, E-mail: alexei_kasatkin@mail.ru, E-mail: lsu@mail.rb.ru
2009-10-15
In this paper, nonlinear anomalous diffusion equations with time fractional derivatives (Riemann-Liouville and Caputo) of the order of 0-2 are considered. Lie point symmetries of these equations are investigated and compared. Examples of using the obtained symmetries for constructing exact solutions of the equations under consideration are presented.
Bradley, D. Nathan
2017-12-01
A consensus has formed that the step length distribution of fluvial bed load is thin tailed and that the observed anomalous superdiffusion of bed load tracer particles must arise from heavy-tailed resting times. However, heavy-tailed resting times have never been directly observed in the field over multiple floods. Using 9 years of data from a large bed load tracer experiment, I show that the spatial variance of the tracer plume scales faster than linearly with integrated excess stream power, indicating anomalous superdiffusion. The superdiffusion is caused by a heavy-tailed distribution of observed storage times that is fit with a truncated Pareto distribution with a tail parameter that is predicted by anomalous diffusion theory. The heavy-tailed distribution of storage times causes the tracer virtual velocity to slow over time, indicated by a sublinear increase in the mean displacement that is predicted by the storage time distribution tail parameter.
Park, Sinwook; Yossifon, Gilad
2014-11-01
The passage of an electric current through an ionic permselective medium under an applied electric field is characterized by the formation of ionic concentration gradients, which result in regions of depleted and enriched ionic concentration at opposite ends of the medium. Induced-current electro-osmosis (ICEO) and alternating-current-electro-osmosis (ACEO) are shown to control the growth of the diffusion layer (DL) which, in turn, controls the diffusion limited ion transport through the microchannel-membrane system. We fabricated and tested devices made of a Nafion membrane connecting two opposite PDMS microchannels. An interdigitated electrode array was embedded within the microchannel with various distances from the microchannel-membrane interface. The induced ICEO (floating electrodes) / ACEO (active electrodes) vortices formed at the electrode array stir the fluid and thereby suppress the growth of the DL. The intensity of the ACEO vortices is controlled by either varying the voltage amplitude or the frequency, each having its own unique effect. Enhancement of the limiting current by on-demand control of the diffusion length is of importance in on-chip electro-dialysis, desalination and preconcentration of analytes.
Extra metal adatom surface diffusion simulation on 1/3 ML Si(111) √3×√3 metal-induced surfaces
International Nuclear Information System (INIS)
Luniakov, Yu V
2013-01-01
A first-principle simulation of the surface diffusion of an extra metal (Me) adatom has been performed on the corresponding 1/3 monolayer (ML) Si(111) √3×√3 Me-induced surfaces. Using the nudged elastic band (NEB) optimization method, the minimum energy paths and the activation energy barrier profiles for all known Me-inducing √3×√3 reconstruction on an Si(111) surface at the 1/3 ML coverage have been obtained and compared with the available experimental data. The activation barrier is shown to depend on the atomic size of the diffusing adatom: the barrier has the highest value for the largest Me adatom, Pb (0.44 eV); lower values for the smaller Me adatoms, Sn (0.36 eV), In (0.22 eV) and Ga (0.13 eV); and the lowest value for the smallest Me adatom, Al (0.08 eV). The Arrhenius pre-exponential factors that were obtained in the harmonic approximation are as large as ∼10 11−13 Hz for all of the investigated surfaces, which supports the single-adatom diffusion model considered here. (paper)
Anomalous dispersion enhanced Cerenkov phase-matching
Energy Technology Data Exchange (ETDEWEB)
Kowalczyk, T.C.; Singer, K.D. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics; Cahill, P.A. [Sandia National Labs., Albuquerque, NM (United States)
1993-11-01
The authors report on a scheme for phase-matching second harmonic generation in polymer waveguides based on the use of anomalous dispersion to optimize Cerenkov phase matching. They have used the theoretical results of Hashizume et al. and Onda and Ito to design an optimum structure for phase-matched conversion. They have found that the use of anomalous dispersion in the design results in a 100-fold enhancement in the calculated conversion efficiency. This technique also overcomes the limitation of anomalous dispersion phase-matching which results from absorption at the second harmonic. Experiments are in progress to demonstrate these results.
Solutions for a diffusion equation with a backbone term
International Nuclear Information System (INIS)
Tateishi, A A; Lenzi, E K; Ribeiro, H V; Evangelista, L R; Mendes, R S; Da Silva, L R
2011-01-01
We investigate the diffusion equation ∂ t ρ=D y ∂ y 2 ρ+D x ∂ x 2 ρ+ D-bar x δ(y)∂ x μ ρ subjected to the boundary conditions ρ(±∞,y;t)=0 and ρ(x,±∞;t)=0, and the initial condition ρ(x,y;0)= ρ-hat (x,y). We obtain exact solutions in terms of the Green function approach and analyze the mean square displacement in the x and y directions. This analysis shows an anomalous spreading of the system which is characterized by different diffusive regimes connected to anomalous diffusion
Anomalous Nernst effect in type-II Weyl semimetals
Saha, Subhodip; Tewari, Sumanta
2018-01-01
Topological Weyl semimetals (WSM), a new state of quantum matter with gapless nodal bulk spectrum and open Fermi arc surface states, have recently sparked enormous interest in condensed matter physics. Based on the symmetry and fermiology, it has been proposed that WSMs can be broadly classified into two types, type-I and type-II Weyl semimetals. While the undoped, conventional, type-I WSMs have point like Fermi surface and vanishing density of states (DOS) at the Fermi energy, the type-II Weyl semimetals break Lorentz symmetry explicitly and have tilted conical spectra with electron and hole pockets producing finite DOS at the Fermi level. The tilted conical spectrum and finite DOS at Fermi level in type-II WSMs have recently been shown to produce interesting effects such as a chiral anomaly induced longitudinal magnetoresistance that is strongly anisotropic in direction and a novel anomalous Hall effect. In this work, we consider the anomalous Nernst effect in type-II WSMs in the absence of an external magnetic field using the framework of semi-classical Boltzmann theory. Based on both a linearized model of time-reversal breaking WSM with a higher energy cut-off and a more realistic lattice model, we show that the anomalous Nernst response in these systems is strongly anisotropic in space, and can serve as a reliable signature of type-II Weyl semimetals in a host of magnetic systems with spontaneously broken time reversal symmetry.
Manning, Kathryn Y; Fehlings, Darcy; Mesterman, Ronit; Gorter, Jan Willem; Switzer, Lauren; Campbell, Craig; Menon, Ravi S
2015-10-01
The aim was to identify neuroimaging predictors of clinical improvements following constraint-induced movement therapy. Resting state functional magnetic resonance and diffusion tensor imaging data was acquired in 7 children with hemiplegic cerebral palsy. Clinical and magnetic resonance imaging (MRI) data were acquired at baseline and 1 month later following a 3-week constraint therapy regimen. A more negative baseline laterality index characterizing an atypical unilateral sensorimotor resting state network significantly correlated with an improvement in the Canadian Occupational Performance Measure score (r = -0.81, P = .03). A more unilateral network with decreased activity in the affected hemisphere was associated with greater improvements in clinical scores. Higher mean diffusivity in the posterior limb of the internal capsule of the affect tract correlated significantly with improvements in the Jebsen-Taylor score (r = -0.83, P = .02). Children with more compromised networks and tracts improved the most following constraint therapy. © The Author(s) 2015.
Spin Hall and spin swapping torques in diffusive ferromagnets
Pauyac, C. O.
2017-12-08
A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.
Spin Hall and spin swapping torques in diffusive ferromagnets
Pauyac, C. O.; Chshiev, M.; Manchon, Aurelien; Nikolaev, S. A.
2017-01-01
A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.
Anomalous neutron scattering and feroelectric modes
International Nuclear Information System (INIS)
Viswanathan, K.S.
1977-01-01
It is suggested that anomalous neutron scattering could prove a powerful experimental tool in studying ferroelectric phase transition, the sublattice displacements of the soft modes as well as their symmetry characteristics. (author)
Origins of the anomalous stress behavior in charged colloidal suspensions under shear.
Kumar, Amit; Higdon, Jonathan J L
2010-11-01
Numerical simulations are conducted to determine microstructure and rheology of sheared suspensions of charged colloidal particles at a volume fraction of ϕ=0.33. Over broad ranges of repulsive force strength F0 and Péclet number Pe, dynamic simulations show coexistence of ordered and disordered stable states with the state dependent on the initial condition. In contrast to the common view, at low shear rates, the disordered phase exhibits a lower viscosity (μ(r)) than the ordered phase, while this behavior is reversed at higher shear rates. Analysis shows the stress reversal is associated with different shear induced microstructural distortions in the ordered and disordered systems. Viscosity vs shear rate data over a wide range of F0 and Pe collapses well upon rescaling with the long-time self-diffusivity. Shear thinning viscosity in the ordered phase scaled as μ(r)∼Pe(-0.81) at low shear rates. The microstructural dynamics revealed in these studies explains the anomalous behavior and hysteresis loops in stress data reported in the literature.
Directory of Open Access Journals (Sweden)
Azhar R Hussain
Full Text Available BACKGROUND: We have recently shown that deregulation PI3-kinase/AKT survival pathway plays an important role in pathogenesis of diffuse large B cell lymphoma (DLBCL. In an attempt to identify newer therapeutic agents, we investigated the role of Resveratrol (trans-3,4', 5-trihydroxystilbene, a naturally occurring polyphenolic compound on a panel of diffuse large B-cell lymphoma (DLBCL cells in causing inhibition of cell viability and inducing apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the action of Resveratrol on DLBCL cells and found that Resveratrol inhibited cell viability and induced apoptosis by inhibition of constitutively activated AKT and its downstream targets via generation of reactive oxygen species (ROS. Simultaneously, Resveratrol treatment of DLBCL cell lines also caused ROS dependent upregulation of DR5; and interestingly, co-treatment of DLBCL with sub-toxic doses of TRAIL and Resveratrol synergistically induced apoptosis via utilizing DR5, on the other hand, gene silencing of DR5 abolished this effect. CONCLUSION/SIGNIFICANCE: Altogether, these data suggest that Resveratrol acts as a suppressor of AKT/PKB pathway leading to apoptosis via generation of ROS and at the same time primes DLBCL cells via up-regulation of DR5 to TRAIL-mediated apoptosis. These data raise the possibility that Resveratrol may have a future therapeutic role in DLBCL and possibly other malignancies with constitutive activation of the AKT/PKB pathway.
International Nuclear Information System (INIS)
Seierstad, Therese; Roe, Kathrine; Olsen, Dag Rune
2007-01-01
Background and purpose: To examine whether in vivo proton magnetic resonance spectroscopy ( 1 H MRS) and diffusion-weighted magnetic resonance imaging (DW-MRI) can monitor radiation-induced changes in HT29 xenografts in mice. Materials and methods: HT29 xenografts in mice received a dose of 15 Gy. In vivo 1 H MRS and DW-MRI were acquired pretreatment and 1, 3, 6 and 10 days post-irradiation. After imaging, tumors were excised for histological analysis. The amounts of necrosis, fibrosis and viable cells in the cross sections were scored and compared to changes in apparent diffusion coefficient (ADC) and choline/water ratio. Results: Radiation-induced necrosis in the xenografts was observed as increased tumor ADC. In-growth of fibrosis three days post-irradiation restricting water mobility was accompanied by decreased tumor ADC. Choline/water ratio correlated with metabolic activity and tumor growth. Conclusions: ADC and choline/water ratio assessed by in vivo DW-MRI and 1 H MRS depicts radiation-induced changes in HT29 xenografts following irradiation
Ross, Robert M; Hartig, Bjoern; McKay, Ryan
2017-09-01
It has been proposed that delusional beliefs are attempts to explain anomalous experiences. Why, then, do anomalous experiences induce delusions in some people but not in others? One possibility is that people with delusions have reasoning biases that result in them failing to reject implausible candidate explanations for anomalous experiences. We examine this hypothesis by studying paranormal interpretations of anomalous experiences. We examined whether analytic cognitive style (i.e. the willingness or disposition to critically evaluate outputs from intuitive processing and engage in effortful analytic processing) predicted anomalous experiences and paranormal explanations for these experiences after controlling for demographic variables and cognitive ability. Analytic cognitive style predicted paranormal explanations for anomalous experiences, but not the anomalous experiences themselves. We did not study clinical delusions. Our attempts to control for cognitive ability may have been inadequate. Our sample was predominantly students. Limited analytic cognitive style might contribute to the interpretation of anomalous experiences in terms of delusional beliefs. Copyright © 2016 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Tokoro, K.; Wikstrom, N.P.; Ojo, O.A.; Chaturvedi, M.C.
2008-01-01
A microstructural study was performed on transient liquid phase (TLP) bonded Waspaloy superalloy with a Ni-Cr-B filler. The applicability of a diffusion model based on Fick's second law of diffusion to determine the time required for complete isothermal solidification (t f ) was investigated. Over the temperature range of 1065-1110 deg. C, experimental observations of t f were in reasonable agreement with t f values predicted by the diffusion model. However, a notable deviation was observed in joints prepared between 1175 and 1225 deg. C in that the rate of isothermal solidification was reduced at these temperatures resulting in the formation of a centerline eutectic-type microconstituent, which in contrast, was prevented from forming after holding the brazing assembly for an equivalent bonding time at a lower temperature of 1145 deg. C. Boride particles were observed as part of the eutectic product, which suggested that diffusion of boron out of the liquated insert was also reduced at these higher temperatures. A decrease in solubility of the melting point depressing solute, boron, with increase in temperature is suggested to be an important factor contributing to the reduction in isothermal solidification rate observed at the higher bonding temperatures
International Nuclear Information System (INIS)
Ghorai, Santu; Poria, Swarup
2016-01-01
In this paper, we have investigated the phenomena of Turing pattern formation in a predator-prey model with habitat complexity in presence of cross diffusion. Using the linear stability analysis, the conditions for the existence of stationary pattern and the existence of Hopf bifurcation are obtained. It is shown analytically that the presence of cross diffusion in the system supports the formation of Turing pattern. Two parameter bifurcation analysis are done analytically and corresponding bifurcation diagrams are presented numerically. A series of simulation results are plotted for different biologically meaningful parameter values. Effects of variation of habitat complexity and the predator mortality rate and birth rate of prey on pattern formation are also reported. It is shown that cross-diffusion can lead to a wide variety of spatial and spatiotemporal pattern formation. It is found that the model exhibits spot and stripe pattern, and coexistence of both spot and strip patterns under the zero flux boundary condition. It is observed that cross-diffusion, habitat complexity, birth rate of prey and predator’s mortality rate play a significant role in the pattern formation of a distributed population system of predator-prey type.
van Heerden, Philippus D R; Kiddle, Guy; Pellny, Till K; Mokwala, Phatlane W; Jordaan, Anine; Strauss, Abram J; de Beer, Misha; Schlüter, Urte; Kunert, Karl J; Foyer, Christine H
2008-09-01
Symbiotic nitrogen fixation is sensitive to dark chilling (7 degrees C-15 degrees C)-induced inhibition in soybean (Glycine max). To characterize the mechanisms that cause the stress-induced loss of nodule function, we examined nodule structure, carbon-nitrogen interactions, and respiration in two soybean genotypes that differ in chilling sensitivity: PAN809 (PAN), which is chilling sensitive, and Highveld Top (HT), which is more chilling resistant. Nodule numbers were unaffected by dark chilling, as was the abundance of the nitrogenase and leghemoglobin proteins. However, dark chilling decreased nodule respiration rates, nitrogenase activities, and NifH and NifK mRNAs and increased nodule starch, sucrose, and glucose in both genotypes. Ureide and fructose contents decreased only in PAN nodules. While the chilling-induced decreases in nodule respiration persisted in PAN even after return to optimal temperatures, respiration started to recover in HT by the end of the chilling period. The area of the intercellular spaces in the nodule cortex and infected zone was greatly decreased in HT after three nights of chilling, an acclimatory response that was absent from PAN. These data show that HT nodules are able to regulate both respiration and the area of the intercellular spaces during chilling and in this way control the oxygen diffusion barrier, which is a key component of the nodule stress response. We conclude that chilling-induced loss of symbiotic nitrogen fixation in PAN is caused by the inhibition of respiration coupled to the failure to regulate the oxygen diffusion barrier effectively. The resultant limitations on nitrogen availability contribute to the greater chilling-induced inhibition of photosynthesis in PAN than in HT.
Anomalous interactions in confined charge-stabilized colloid
International Nuclear Information System (INIS)
Grier, D G; Han, Y
2004-01-01
Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are supposed to repel each other. Consequently, experimental evidence for anomalous long-ranged like-charged attractions induced by geometric confinement inspired a burst of activity. This has largely subsided because of nagging doubts regarding the experiments' reliability and interpretation. We describe a new class of thermodynamically self-consistent colloidal interaction measurements that confirm the appearance of pairwise attractions among colloidal spheres confined by one or two bounding walls. In addition to supporting previous claims for this as-yet unexplained effect, these measurements also cast new light on its mechanism
Anomalous sea surface structures as an object of statistical topography
Klyatskin, V. I.; Koshel, K. V.
2015-06-01
By exploiting ideas of statistical topography, we analyze the stochastic boundary problem of emergence of anomalous high structures on the sea surface. The kinematic boundary condition on the sea surface is assumed to be a closed stochastic quasilinear equation. Applying the stochastic Liouville equation, and presuming the stochastic nature of a given hydrodynamic velocity field within the diffusion approximation, we derive an equation for a spatially single-point, simultaneous joint probability density of the surface elevation field and its gradient. An important feature of the model is that it accounts for stochastic bottom irregularities as one, but not a single, perturbation. Hence, we address the assumption of the infinitely deep ocean to obtain statistic features of the surface elevation field and the squared elevation gradient field. According to the calculations, we show that clustering in the absolute surface elevation gradient field happens with the unit probability. It results in the emergence of rare events such as anomalous high structures and deep gaps on the sea surface almost in every realization of a stochastic velocity field.
Chiral anomaly and anomalous finite-size conductivity in graphene
Shen, Shun-Qing; Li, Chang-An; Niu, Qian
2017-09-01
Graphene is a monolayer of carbon atoms packed into a hexagon lattice to host two spin degenerate pairs of massless two-dimensional Dirac fermions with different chirality. It is known that the existence of non-zero electric polarization in reduced momentum space which is associated with a hidden chiral symmetry will lead to the zero-energy flat band of a zigzag nanoribbon and some anomalous transport properties. Here it is proposed that the Adler-Bell-Jackiw chiral anomaly or non-conservation of chiral charges of Dirac fermions at different valleys can be realized in a confined ribbon of finite width, even in the absence of a magnetic field. In the laterally diffusive regime, the finite-size correction to conductivity is always positive and is inversely proportional to the square of the lateral dimension W, which is different from the finite-size correction inversely proportional to W from the boundary modes. This anomalous finite-size conductivity reveals the signature of the chiral anomaly in graphene, and it is measurable experimentally. This finding provides an alternative platform to explore the purely quantum mechanical effect in graphene.
Anomalous energy transport in hot plasmas: solar corona and Tokamak
International Nuclear Information System (INIS)
Beaufume, P.
1992-04-01
Anomalous energy transport is studied in two hot plasmas and appears to be associated with a heating of the solar corona and with a plasma deconfining process in tokamaks. The magnetic structure is shown to play a fundamental role in this phenomenon through small scale instabilities which are modelized by means of a nonlinear dynamical system: the Beasts' Model. Four behavior classes are found for this system, which are automatically classified in the parameter space thanks to a neural network. We use a compilation of experimental results relative to the solar corona to discuss current-based heating processes. We find that a simple Joule effect cannot provide the required heating rates, and therefore propose a dimensional model involving a resistive reconnective instability which leads to an efficient and discontinuous heating mechanism. Results are in good agreement with the observations. We give an analytical expression for a diffusion coefficient in tokamaks when magnetic turbulence is perturbing the topology, which we validate thanks to the standard mapping. A realistic version of the Beasts' Model allows to test a candidate to anomalous transport: the thermal filamentation instability
Energy Technology Data Exchange (ETDEWEB)
Ren, Cui-Lan, E-mail: rencuilan@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800 (China); Han, Han [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Gong, Wen-Bin [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Shanghai 215123 (China); Wang, Cheng-Bin; Zhang, Wei [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800 (China); Cheng, Cheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Huai, Ping, E-mail: huaiping@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Zhu, Zhi-Yuan [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800 (China)
2016-09-15
Adsorption and diffusion behaviors of fluorine on Cr-doped Ni(111) surface are investigated by using first-principles simulation. It shows that the Cr in the Cr-doped Ni(111) surface serve a trap site for fluorine with adsorption energy 3.52 eV, which is 1.04 eV higher than that on Ni(111) surface. Moreover, the Cr atom is pulled out the surface for 0.41 Å after the fluorine adsorption, much higher than that on Ni(111) surface. Further diffusion behaviors analysis confirms the conclusion because the fluorine diffusion from neighbored sites onto the Cr top site is an energy barrierless process. Detailed electronic structure analysis shows that a deeper hybrid state of F 2 p-Cr 3 d indicates a strong F−Cr interaction. The Ni−Cr bond is elongated and weakened due to the new formed F−Cr bonding. Our results help to understanding the basic fluorine-induced initial corrosion mechanism for Ni-based alloy in molten salt environment.
Wan, Qi; Wang, Shiyang; Zhou, Jiaxuan; Zou, Qiao; Deng, Yingshi; Wang, Shouyang; Zheng, Xiaoying; Li, Xinchun
2016-06-01
To investigate the potential of diffusion tensor imaging (DTI) and T2 measurements in the evaluation of radiation-induced peripheral nerve injury (RIPNI). RIPNI was produced in a randomly selected side of sciatic nerve in each of 21 rabbits while the contralateral side served as the control. The limb function and MR parameters were evaluated over a 4-month period. Fractional anisotropy (FA), axial diffusivity (λ∥ ), radial diffusivity (λ⊥ ) and T2 values were obtained using 3T MR for quantitative analysis. Two animals were randomly killed for histological evaluation at each timepoint. The T2 value of irradiated nerve increased at 1 day (63.95 ± 15.60, P = 0.012) and was restored at 1 month (52.34 ± 5.38, P = 0.105). It increased progressively at 2 to 4 months (60.39 ± 10.60, 66.96 ± 6.08, 75.51 ± 7.39, all P evaluate RIPNI compared with T2 measurements. FA and λ⊥ are promising quantitative indices in monitoring RIPNI. J. Magn. Reson. Imaging 2016;43:1492-1499. © 2015 Wiley Periodicals, Inc.
Guo, Zaibing
2015-05-01
The effect of interfacial intermixing on magnetization and anomalous Hall effect (AHE) in Co/Pd multilayers is studied by using rapid thermal annealing to enhance the interfacial diffusion. The dependence of saturation magnetization and coercivity on the temperature of rapid thermal annealing at 5 K is discussed. It is found that AHE is closely related to the relative thickness of the Co and Pd layers. Localized paramagnetism has been observed which destroys AHE, while AHE can be enhanced by annealing.
Anomalous radon emission as precursor of medium to strong earthquakes
Energy Technology Data Exchange (ETDEWEB)
Zoran, Maria [National Institute of R& D for Optoelectronics, MG5 Bucharest -Magurele, 077125 Romania (Romania)
2016-03-25
Anomalous radon (Rn{sup 222}) emissions enhanced by forthcoming earthquakes is considered to be a precursory phenomenon related to an increased geotectonic activity in seismic areas. Rock microfracturing in the Earth’s crust preceding a seismic rupture may cause local surface deformation fields, rock dislocations, charged particle generation and motion, electrical conductivity changes, radon and other gases emission, fluid diffusion, electrokinetic, piezomagnetic and piezoelectric effects as well as climate fluctuations. Space-time anomalies of radon gas emitted in underground water, soil and near the ground air weeks to days in the epicentral areas can be associated with the strain stress changes that occurred before the occurrence of medium and strong earthquakes. This paper aims to investigate temporal variations of radon concentration levels in air near or in the ground by the use of solid state nuclear track detectors (SSNTD) CR-39 and LR-115 in relation with some important seismic events recorded in Vrancea region, Romania.
Temporal correlation functions of concentration fluctuations: an anomalous case.
Lubelski, Ariel; Klafter, Joseph
2008-10-09
We calculate, within the framework of the continuous time random walk (CTRW) model, multiparticle temporal correlation functions of concentration fluctuations (CCF) in systems that display anomalous subdiffusion. The subdiffusion stems from the nonstationary nature of the CTRW waiting times, which also lead to aging and ergodicity breaking. Due to aging, a system of diffusing particles tends to slow down as time progresses, and therefore, the temporal correlation functions strongly depend on the initial time of measurement. As a consequence, time averages of the CCF differ from ensemble averages, displaying therefore ergodicity breaking. We provide a simple example that demonstrates the difference between these two averages, a difference that might be amenable to experimental tests. We focus on the case of ensemble averaging and assume that the preparation time of the system coincides with the starting time of the measurement. Our analytical calculations are supported by computer simulations based on the CTRW model.
Delay-induced Turing-like waves for one-species reaction-diffusion model on a network
Petit, Julien; Carletti, Timoteo; Asllani, Malbor; Fanelli, Duccio
2015-09-01
A one-species time-delay reaction-diffusion system defined on a complex network is studied. Traveling waves are predicted to occur following a symmetry-breaking instability of a homogeneous stationary stable solution, subject to an external nonhomogeneous perturbation. These are generalized Turing-like waves that materialize in a single-species populations dynamics model, as the unexpected byproduct of the imposed delay in the diffusion part. Sufficient conditions for the onset of the instability are mathematically provided by performing a linear stability analysis adapted to time-delayed differential equations. The method here developed exploits the properties of the Lambert W-function. The prediction of the theory are confirmed by direct numerical simulation carried out for a modified version of the classical Fisher model, defined on a Watts-Strogatz network and with the inclusion of the delay.
Streamlined Modeling for Characterizing Spacecraft Anomalous Behavior
Klem, B.; Swann, D.
2011-09-01
Anomalous behavior of on-orbit spacecraft can often be detected using passive, remote sensors which measure electro-optical signatures that vary in time and spectral content. Analysts responsible for assessing spacecraft operational status and detecting detrimental anomalies using non-resolved imaging sensors are often presented with various sensing and identification issues. Modeling and measuring spacecraft self emission and reflected radiant intensity when the radiation patterns exhibit a time varying reflective glint superimposed on an underlying diffuse signal contribute to assessment of spacecraft behavior in two ways: (1) providing information on body component orientation and attitude; and, (2) detecting changes in surface material properties due to the space environment. Simple convex and cube-shaped spacecraft, designed to operate without protruding solar panel appendages, may require an enhanced level of preflight characterization to support interpretation of the various physical effects observed during on-orbit monitoring. This paper describes selected portions of the signature database generated using streamlined signature modeling and simulations of basic geometry shapes apparent to non-imaging sensors. With this database, summarization of key observable features for such shapes as spheres, cylinders, flat plates, cones, and cubes in specific spectral bands that include the visible, mid wave, and long wave infrared provide the analyst with input to the decision process algorithms contained in the overall sensing and identification architectures. The models typically utilize baseline materials such as Kapton, paints, aluminum surface end plates, and radiators, along with solar cell representations covering the cylindrical and side portions of the spacecraft. Multiple space and ground-based sensors are assumed to be located at key locations to describe the comprehensive multi-viewing aspect scenarios that can result in significant specular reflection
Spin diffusion in disordered organic semiconductors
Li, Ling; Gao, Nan; Lu, Nianduan; Liu, Ming; Bässler, Heinz
2015-12-01
An analytical theory for spin diffusion in disordered organic semiconductors is derived. It is based on percolation theory and variable range hopping in a disordered energy landscape with a Gaussian density of states. It describes universally the dependence of the spin diffusion on temperature, carrier density, material disorder, magnetic field, and electric field at the arbitrary magnitude of the Hubbard energy of charge pairs. It is found that, compared to the spin transport carried by carriers hopping, the spin exchange will hinder the spin diffusion process at low carrier density, even under the condition of a weak electric field. Importantly, under the influence of a bias voltage, anomalous spreading of the spin packet will lead to an abnormal temperature dependence of the spin diffusion coefficient and diffusion length. This explains the recent experimental data for spin diffusion length observed in Alq3.
An Efficient Implicit FEM Scheme for Fractional-in-Space Reaction-Diffusion Equations
Burrage, Kevin; Hale, Nicholas; Kay, David
2012-01-01
Fractional differential equations are becoming increasingly used as a modelling tool for processes associated with anomalous diffusion or spatial heterogeneity. However, the presence of a fractional differential operator causes memory (time
Live-monitoring of Te inclusions laser-induced thermo-diffusion and annealing in CdZnTe crystals
International Nuclear Information System (INIS)
Zappettini, A.; Zambelli, N.; Benassi, G.; Calestani, D.; Pavesi, M.
2014-01-01
The presence of Te inclusions is one of the main factors limiting performances of CdZnTe crystals as X-ray detectors. We show that by means of infrared laser radiation it is possible to move and anneal tellurium inclusions exploiting a thermo-diffusion mechanism. The process is studied live during irradiation by means of an optical microscope equipment. Experimental conditions, and, in particular, energy laser fluence, for annealing inclusions of different dimensions are determined.
Live-monitoring of Te inclusions laser-induced thermo-diffusion and annealing in CdZnTe crystals
Energy Technology Data Exchange (ETDEWEB)
Zappettini, A.; Zambelli, N.; Benassi, G.; Calestani, D. [Istituto Materiali Elettronica e Magnetismo – Consiglio Nazionale delle Ricerche, Parma (Italy); Pavesi, M. [Istituto Materiali Elettronica e Magnetismo – Consiglio Nazionale delle Ricerche, Parma (Italy); Istituto di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma (Italy)
2014-06-23
The presence of Te inclusions is one of the main factors limiting performances of CdZnTe crystals as X-ray detectors. We show that by means of infrared laser radiation it is possible to move and anneal tellurium inclusions exploiting a thermo-diffusion mechanism. The process is studied live during irradiation by means of an optical microscope equipment. Experimental conditions, and, in particular, energy laser fluence, for annealing inclusions of different dimensions are determined.
Czech Academy of Sciences Publication Activity Database
Sotiriadis, Konstantinos; Rakanta, E.; Mitzithra, M. E.; Batis, G.; Tsivilis, S.
2017-01-01
Roč. 29, č. 8 (2017), č. článku 04017060. ISSN 0899-1561 R&D Projects: GA MŠk(CZ) LO1219 Keywords : limestone cement * chloride diffusion * reinforcement corrosion * sulfate attack * low temperature Subject RIV: JN - Civil Engineering OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 1.644, year: 2016 http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29MT.1943-5533.0001895
Li, Fu-Min; Kang, Yong-Qiang; Liu, Hui-Min; Zhai, Ya-Nan; Hu, Man-Cheng; Chen, Yu
2018-03-15
Bimetallic noble metal nanocrystals have been widely applied in many fields, which generally are synthesized by the wet-chemistry reduction method. This work presents a purposely designed atoms diffusion induced phase engineering of PtAu alloy nanocrystals on platy Au substrate (PtAu-on-Au nanostructures) through simple hydrothermal treatment. Benefitting from the synergistic effects of component and structure, PtAu-on-Au nanostructures remarkably enhance the dehydrogenation pathway of the formic acid oxidation reaction (FAOR), and thus exhibit much higher FAOR activity and durability compared with Pt nanocrystals on platy Au substrate (Pt-on-Au nanostructures) and commercial Pd black due to an excellent stability of platy Au substrate and a high oxidation resistance of PtAu alloy nanocrystals. The atoms diffusion-induced phase engineering demonstrated in this work builds a bridge between the traditional metallurgy and modern nanotechnologies, which also provides some useful insights in developing noble metals based alloyed nanostructures for the energy and environmental applications. Copyright © 2017 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Yamagishi, Tomejiro; Sanuki, Heiji.
1996-01-01
Anomalous cross field plasma fluxes induced by the electric field fluctuations has been evaluated in a rotating plasma with shear flow in a helical system. The anomalous ion flux is evaluated by the contribution from ion curvature drift resonance continuum in the test particle model. The radial electric field induces the Doppler frequency shift which disappears in the frequency integrated anomalous flux. The inhomogeneity of the electric field (shear flow effect), however, induces a new force term in the flux. The curvature drift resonance also induces a new force term '/ which, however, did not make large influence in the ion flux in the CHS configuration. The shear flow term in the flux combined with the electric field in neoclassical flux reduces to a first order differential equation which governs the radial profile of the electric field. Numerical results indicate that the shear flow effect is important for the anomalous cross field flux and for determination of the radial electric field particularly in the peripheral region. (author)
1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport
International Nuclear Information System (INIS)
Li, Yunyun; Li, Nianbei; Hänggi, Peter; Li, Baowen; Liu, Sha
2015-01-01
Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an
1D momentum-conserving systems: the conundrum of anomalous versus normal heat transport
Li, Yunyun; Liu, Sha; Li, Nianbei; Hänggi, Peter; Li, Baowen
2015-04-01
Transport and the spread of heat in Hamiltonian one dimensional momentum conserving nonlinear systems is commonly thought to proceed anomalously. Notable exceptions, however, do exist of which the coupled rotator model is a prominent case. Therefore, the quest arises to identify the origin of manifest anomalous energy and momentum transport in those low dimensional systems. We develop the theory for both, the statistical densities for momentum- and energy-spread and particularly its momentum-/heat-diffusion behavior, as well as its corresponding momentum/heat transport features. We demonstrate that the second temporal derivative of the mean squared deviation of the momentum spread is proportional to the equilibrium correlation of the total momentum flux. Subtracting the part which corresponds to a ballistic momentum spread relates (via this integrated, subleading momentum flux correlation) to an effective viscosity, or equivalently, to the underlying momentum diffusivity. We next put forward the intriguing hypothesis: normal spread of this so adjusted excess momentum density causes normal energy spread and alike normal heat transport (Fourier Law). Its corollary being that an anomalous, superdiffusive broadening of this adjusted excess momentum density in turn implies an anomalous energy spread and correspondingly anomalous, superdiffusive heat transport. This hypothesis is successfully corroborated within extensive molecular dynamics simulations over large extended time scales. Our numerical validation of the hypothesis involves four distinct archetype classes of nonlinear pair-interaction potentials: (i) a globally bounded pair interaction (the noted coupled rotator model), (ii) unbounded interactions acting at large distances (the coupled rotator model amended with harmonic pair interactions), (iii) the case of a hard point gas with unbounded square-well interactions and (iv) a pair interaction potential being unbounded at short distances while displaying an
Directory of Open Access Journals (Sweden)
I.L. Animasaun
2016-06-01
Full Text Available This article presents the effects of nonlinear thermal radiation and induced magnetic field on viscoelastic fluid flow toward a stagnation point. It is assumed that there exists a kind of chemical reaction between chemical species A and B. The diffusion coefficients of the two chemical species in the viscoelastic fluid flow are unequal. Since chemical species B is a catalyst at the horizontal surface, hence homogeneous and heterogeneous schemes are of the isothermal cubic autocatalytic reaction and first order reaction respectively. The transformed governing equations are solved numerically using Runge–Kutta integration scheme along with Newton’s method. Good agreement is obtained between present and published numerical results for a limiting case. The influence of some pertinent parameters on skin friction coefficient, local heat transfer rate, together with velocity, induced magnetic field, temperature, and concentration profiles is illustrated graphically and discussed. Based on all of these assumptions, results indicate that the effects of induced magnetic and viscoelastic parameters on velocity, transverse velocity and velocity of induced magnetic field are almost the same but opposite in nature. The strength of heterogeneous reaction parameter is very helpful to reduce the concentration of bulk fluid and increase the concentration of catalyst at the surface.
The vector meson with anomalous magnetic moment
International Nuclear Information System (INIS)
Boyarkin, O.M.
1976-01-01
The possibility of introducing an anomalous magnetic moment into the Stuckelberg version of the charged vector meson theory is considered. It is shown that the interference of states with spins equal to one and zero is absent in the presence of an anomalous magnetic moment of a particle. The differential cross section of scattering on the Coulomb field of a nucleus is calculated, and so are the differential and integral cross sections of meson pair production on annihilation of two gamma quanta. The two-photon mechanism of production of a meson pair in colliding electron-positron beams is considered. It is shown that with any value of the anomalous magnetic moment the cross section of the esup(+)esup(-) → esup(+)esup(-)γsup(*)γsup(*) → esup(+)esup(-)Wsup(+)Wsup(-) reaction exceeds that of the esup(+)esup(-) → γsup(*) → Wsup(+)Wsup(-) at sufficiently high energies
The anomalous magnetic moment of the muon
Jegerlehner, Friedrich
2017-01-01
This research monograph covers extensively the theory of the muon anomalous magnetic moment and provides estimates of the theoretical uncertainties. The muon anomalous magnetic moment is one of the most precisely measured quantities in elementary particle physics and provides one of the most stringent tests of relativistic quantum field theory as a fundamental theoretical framework. It allows for an extremely precise check of the standard model of elementary particles and of its limitations. This book reviews the present state of knowledge of the anomalous magnetic moment a=(g-2)/2 of the muon. Recent experiments at the Brookhaven National Laboratory now reach the unbelievable precision of 0.5 parts per million, improving the accuracy of previous g-2 experiments at CERN by a factor of 14. In addition, quantum electrodynamics and electroweak and hadronic effects are reviewed. Since non-perturbative hadronic effects play a key role for the precision test, their evaluation is described in detail. Perspectives fo...
Total least squares for anomalous change detection
Theiler, James; Matsekh, Anna M.
2010-04-01
A family of subtraction-based anomalous change detection algorithms is derived from a total least squares (TLSQ) framework. This provides an alternative to the well-known chronochrome algorithm, which is derived from ordinary least squares. In both cases, the most anomalous changes are identified with the pixels that exhibit the largest residuals with respect to the regression of the two images against each other. The family of TLSQbased anomalous change detectors is shown to be equivalent to the subspace RX formulation for straight anomaly detection, but applied to the stacked space. However, this family is not invariant to linear coordinate transforms. On the other hand, whitened TLSQ is coordinate invariant, and special cases of it are equivalent to canonical correlation analysis and optimized covariance equalization. What whitened TLSQ offers is a generalization of these algorithms with the potential for better performance.
Charge-dependent correlations from event-by-event anomalous hydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Hirono, Yuji [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Hirano, Tetsufumi [Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Kharzeev, Dmitri E. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Department of Physics and RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)
2016-12-15
We report on our recent attempt of quantitative modeling of the Chiral Magnetic Effect (CME) in heavy-ion collisions. We perform 3+1 dimensional anomalous hydrodynamic simulations on an event-by-event basis, with constitutive equations that contain the anomaly-induced effects. We also develop a model of the initial condition for the axial charge density that captures the statistical nature of random chirality imbalances created by the color flux tubes. Basing on the event-by-event hydrodynamic simulations for hundreds of thousands of collisions, we calculate the correlation functions that are measured in experiments, and discuss how the anomalous transport affects these observables.
Characteristics of off-waist incident anomalous vortex beams in highly nonlocal media
Directory of Open Access Journals (Sweden)
Zhen-Feng Yang
Full Text Available In this paper, we focus on the effect of the off-waist incident condition on the propagation characteristics of anomalous vortex beams (AVBs in nonlocal media. An expression is derived mathematically in order to describe the propagation dynamics of AVBs in nonlocal media under the off-waist incident condition. Typical propagation characteristics induced by the off-waist incident condition are illustrated numerically. It is found that the propagation characteristics under the off-waist incident condition are much different from those under the on-waist incident condition. Keywords: Off-waist incidence, Anomalous vortex beam, Nonlocal media
Anomalous fracture toughness of irradiated Cr-MoV - Reactor pressure vessel steel
Energy Technology Data Exchange (ETDEWEB)
Ahistrand, R [Imatran Voima Oy (IVO), Helsinki (Finland)
1994-12-31
The base metal Crack Opening Displacement (COD) specimens of the irradiation-induced embrittlement surveillance programme in Loviisa 1 revealed an anomalous behaviour of K{sub JC} compared to the Charpy-V results and to expected results according to standards: about 20% of the COD specimens showed an exceptionally low fracture toughness. Abnormal test specimens were analyzed through fractography, metallography and repeated tests using reconstitution technique: the anomalous behaviour appears to be caused by incorrect pre-fatigue cracking of base metal COD specimens. 7 refs., 9 figs.
Development of anomalous detection using movie prediction
International Nuclear Information System (INIS)
Sakakibara, Yoji; Demachi, Kazuyuki; Kawai, Masaki; Chhatluli, Ritu; Kamiaka, Kazuma
2012-01-01
In this research, the new method to predict the near-future of the movie images captured by video camera based on the combination of the Principle Component Analysis (PCA) and the Singular Spectral Analysis (SSA). In the normal condition of machines, the real-time captured movie is supposed to correspond to the predicted one. If the error between the both becomes significantly large, it may suggest some anomalous motion of the machines. So the movie prediction method has a possibility of the sensitive anomalous detection system. (author)
Directory of Open Access Journals (Sweden)
Xi Shao
2016-03-01
Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.
Directory of Open Access Journals (Sweden)
Rasoul Nikbakhti
2016-03-01
Full Text Available This paper deals with a numerical investigation of double-diffusive natural convective heat and mass transfer in a cavity filled with Newtonian fluid. The active parts of two vertical walls of the cavity are maintained at fixed but different temperatures and concentrations, while the other two walls, as well as inactive areas of the sidewalls, are considered to be adiabatic and impermeable to mass transfer. The length of the thermally active part equals half of the height. The non-dimensional forms of governing transport equations that describe double-diffusive natural convection for two-dimensional incompressible flow are functions of temperature or energy, concentration, vorticity, and stream-function. The coupled differential equations are discretized via FDM (Finite Difference Method. The Successive-Over-Relaxation (SOR method is used in the solution of the stream function equation. The analysis has been done for an enclosure with different aspect ratios ranging from 0.5 to 11 for three different combinations of partially active sections. The results are presented graphically in terms of streamlines, isotherms and isoconcentrations. In addition, the heat and mass transfer rate in the cavity is measured in terms of the average Nusselt and Sherwood numbers for various parameters including thermal Grashof number, Lewis number, buoyancy ratio and aspect ratio. It is revealed that the placement order of partially thermally active walls and the buoyancy ratio influence significantly the flow pattern and the corresponding heat and mass transfer performance in the cavity.
Anomalous transport phenomena in Fermi liquids with strong magnetic fluctuations
International Nuclear Information System (INIS)
Kontani, Hiroshi
2008-01-01
In this paper, we present recent developments in the theory of transport phenomena based on the Fermi liquid theory. In conventional metals, various transport coefficients are scaled according to the quasiparticles relaxation time, τ, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems. The most famous example would be high-T c superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. This issue has been one of the most significant unresolved problems in HTSCs for a long time. Similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). The main goal of this study is to demonstrate whether the anomalous transport phenomena in HTSC is evidence of a non-Fermi liquid ground state, or just RTA violation in strongly correlated Fermi liquids. Another goal is to establish a unified theory of anomalous transport phenomena in metals with strong magnetic fluctuations. For these purposes, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. In a Fermi liquid, an excited quasiparticle induces other excited quasiparticles by collision, and current due to these excitations is called a current vertex correction (CVC). Landau noticed the existence of CVC first, which is indispensable for calculating transport coefficients in accord with the conservation laws. Here, we develop a transport theory involving resistivity and the Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the CVC. In nearly AF Fermi liquids, we find that the strong backward scattering due to AF fluctuations induces the CVC with prominent momentum dependence. This feature of the CVC can account for the significant enhancement in the Hall coefficient, magnetoresistance
Energy Technology Data Exchange (ETDEWEB)
Carella, Alfredo Raul
2012-09-15
Quantifying species transport rates is a main concern in chemical and petrochemical industries. In particular, the design and operation of many large-scale industrial chemical processes is as much dependent on diffusion as it is on reaction rates. However, the existing diffusion models sometimes fail to predict experimentally observed behaviors and their accuracy is usually insufficient for process optimization purposes. Fractional diffusion models offer multiple possibilities for generalizing Flick's law in a consistent manner in order to account for history dependence and nonlocal effects. These models have not been extensively applied to the study of real systems, mainly due to their computational cost and mathematical complexity. A least squares spectral formulation was developed for solving fractional differential equations. The proposed method was proven particularly well-suited for dealing with the numerical difficulties inherent to fractional differential operators. The practical implementation was explained in detail in order to enhance reproducibility, and directions were specified for extending it to multiple dimensions and arbitrarily shaped domains. A numerical framework based on the least-squares spectral element method was developed for studying and comparing anomalous diffusion models in pellets. This simulation tool is capable of solving arbitrary integro-differential equations and can be effortlessly adapted to various problems in any number of dimensions. Simulations of the flow around a cylindrical particle were achieved by extending the functionality of the developed framework. A test case was analyzed by coupling the boundary condition yielded by the fluid model with two families of anomalous diffusion models: hyperbolic diffusion and fractional diffusion. Qualitative guidelines for determining the suitability of diffusion models can be formulated by complementing experimental data with the results obtained from this approach.(Author)
Anomalous Hall effect scaling in ferromagnetic thin films
Grigoryan, Vahram L.
2017-10-23
We propose a scaling law for anomalous Hall effect in ferromagnetic thin films. Our approach distinguishes multiple scattering sources, namely, bulk impurity, phonon for Hall resistivity, and most importantly the rough surface contribution to longitudinal resistivity. In stark contrast to earlier laws that rely on temperature- and thickness-dependent fitting coefficients, this scaling law fits the recent experimental data excellently with constant parameters that are independent of temperature and film thickness, strongly indicating that this law captures the underlying physical processes. Based on a few data points, this scaling law can even fit all experimental data in full temperature and thickness range. We apply this law to interpret the experimental data for Fe, Co, and Ni and conclude that (i) the phonon-induced skew scattering is unimportant as expected; (ii) contribution from the impurity-induced skew scattering is negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and both the extrinsic and intrinsic contributions are important in Ni.
Anomalous Hall effect scaling in ferromagnetic thin films
Grigoryan, Vahram L.; Xiao, Jiang; Wang, Xuhui; Xia, Ke
2017-01-01
We propose a scaling law for anomalous Hall effect in ferromagnetic thin films. Our approach distinguishes multiple scattering sources, namely, bulk impurity, phonon for Hall resistivity, and most importantly the rough surface contribution to longitudinal resistivity. In stark contrast to earlier laws that rely on temperature- and thickness-dependent fitting coefficients, this scaling law fits the recent experimental data excellently with constant parameters that are independent of temperature and film thickness, strongly indicating that this law captures the underlying physical processes. Based on a few data points, this scaling law can even fit all experimental data in full temperature and thickness range. We apply this law to interpret the experimental data for Fe, Co, and Ni and conclude that (i) the phonon-induced skew scattering is unimportant as expected; (ii) contribution from the impurity-induced skew scattering is negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and both the extrinsic and intrinsic contributions are important in Ni.
Anomalous transport at weak coupling
International Nuclear Information System (INIS)
Chowdhury, Subham Dutta; David, Justin R.
2015-01-01
We evaluate the contribution of chiral fermions in d=2,4,6, chiral bosons, a chiral gravitino like theory in d=2 and chiral gravitinos in d=6 to all the leading parity odd transport coefficients at one loop. This is done by using finite temperature field theory to evaluate the relevant Kubo formulae. For chiral fermions and chiral bosons the relation between the parity odd transport coefficient and the microscopic anomalies including gravitational anomalies agree with that found by using the general methods of hydrodynamics and the argument involving the consistency of the Euclidean vacuum. For the gravitino like theory in d=2 and chiral gravitinos in d=6, we show that relation between the pure gravitational anomaly and parity odd transport breaks down. From the perturbative calculation we clearly identify the terms that contribute to the anomaly polynomial, but not to the transport coefficient for gravitinos. We also develop a simple method for evaluating the angular integrals in the one loop diagrams involved in the Kubo formulae. Finally we show that charge diffusion mode of an ideal 2 dimensional Weyl gas in the presence of a finite chemical potential acquires a speed, which is equal to half the speed of light.
Anomalous thermoelectric phenomena in lattice models of multi-Weyl semimetals
Gorbar, E. V.; Miransky, V. A.; Shovkovy, I. A.; Sukhachov, P. O.
2017-10-01
The thermoelectric transport coefficients are calculated in a generic lattice model of multi-Weyl semimetals with a broken time-reversal symmetry by using the Kubo's linear response theory. The contributions connected with the Berry curvature-induced electromagnetic orbital and heat magnetizations are systematically taken into account. It is shown that the thermoelectric transport is profoundly affected by the nontrivial topology of multi-Weyl semimetals. In particular, the calculation reveals a number of thermal coefficients of the topological origin which describe the anomalous Nernst and thermal Hall effects in the absence of background magnetic fields. Similarly to the anomalous Hall effect, all anomalous thermoelectric coefficients are proportional to the integer topological charge of the Weyl nodes. The dependence of the thermoelectric coefficients on the chemical potential and temperature is also studied.
Stefferson, Michael W.; Norris, Samantha L.; Vernerey, Franck J.; Betterton, Meredith D.; E Hough, Loren
2017-08-01
Crowded environments modify the diffusion of macromolecules, generally slowing their movement and inducing transient anomalous subdiffusion. The presence of obstacles also modifies the kinetics and equilibrium behavior of tracers. While previous theoretical studies of particle diffusion have typically assumed either impenetrable obstacles or binding interactions that immobilize the particle, in many cellular contexts bound particles remain mobile. Examples include membrane proteins or lipids with some entry and diffusion within lipid domains and proteins that can enter into membraneless organelles or compartments such as the nucleolus. Using a lattice model, we studied the diffusive movement of tracer particles which bind to soft obstacles, allowing tracers and obstacles to occupy the same lattice site. For sticky obstacles, bound tracer particles are immobile, while for slippery obstacles, bound tracers can hop without penalty to adjacent obstacles. In both models, binding significantly alters tracer motion. The type and degree of motion while bound is a key determinant of the tracer mobility: slippery obstacles can allow nearly unhindered diffusion, even at high obstacle filling fraction. To mimic compartmentalization in a cell, we examined how obstacle size and a range of bound diffusion coefficients affect tracer dynamics. The behavior of the model is similar in two and three spatial dimensions. Our work has implications for protein movement and interactions within cells.
Energy Technology Data Exchange (ETDEWEB)
Adams, Hugo J.A.; Nievelstein, Rutger A.J.; Kwee, Thomas C. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); Klerk, John M.H. de [Meander Medical Center, Department of Nuclear Medicine, Amersfoort (Netherlands); Fijnheer, Rob [Meander Medical Center, Department of Hematology, Amersfoort (Netherlands); Heggelman, Ben G.F. [Meander Medical Center, Department of Radiology, Amersfoort (Netherlands); Dubois, Stefan V. [Meander Medical Center, Department of Pathology, Amersfoort (Netherlands)
2015-05-01
To determine the prognostic value of tumor-induced cortical bone destruction at computed tomography (CT) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). This retrospective study included 105 patients with newly diagnosed DLBCL who had undergone CT and bone marrow biopsy (BMB) before R-CHOP (rituximab, cyclophosphamide, hydroxydaunorubicin, Oncovin, and prednisolone) chemo-immunotherapy. Cox regression analyses were used to determine the associations of cortical bone status at CT (absence vs. presence of tumor-induced cortical bone destruction), BMB findings (negative vs. positive for lymphomatous involvement), and dichotomized National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) strata (low risk vs. high risk) with progression-free survival (PFS) and overall survival (OS). Univariate Cox regression analysis indicated that cortical bone status at CT was no significant predictor of either PFS or OS (p = 0.358 and p = 0.560, respectively), whereas BMB findings (p = 0.002 and p = 0.013, respectively) and dichotomized NCCN-IPI risk strata (p = 0.002 and p = 0.003, respectively) were significant predictors of both PFS and OS. In the multivariate Cox proportional hazards model, only the dichotomized NCCN-IPI score was an independent predictive factor of PFS and OS (p = 0.004 and p = 0.003, respectively). The presence of tumor-induced cortical bone destruction at CT was not found to have any prognostic implications in newly diagnosed DLBCL. (orig.)
Anomalous Hall effect in semiconductor quantum wells in proximity to chiral p -wave superconductors
Yang, F.; Yu, T.; Wu, M. W.
2018-05-01
By using the gauge-invariant optical Bloch equation, we perform a microscopic kinetic investigation on the anomalous Hall effect in chiral p -wave superconducting states. Specifically, the intrinsic anomalous Hall conductivity in the absence of the magnetic field is zero as a consequence of Galilean invariance in our description. As for the extrinsic channel, a finite anomalous Hall current is obtained from the impurity scattering with the optically excited normal quasiparticle current even at zero temperature. From our kinetic description, it can be clearly seen that the excited normal quasiparticle current is due to an induced center-of-mass momentum of Cooper pairs through the acceleration driven by ac electric field. For the induced anomalous Hall current, we show that the conventional skew-scattering channel in the linear response makes the dominant contribution in the strong impurity interaction. In this case, our kinetic description as a supplementary viewpoint mostly confirms the results of Kubo formalism in the literature. Nevertheless, in the weak impurity interaction, this skew-scattering channel becomes marginal and we reveal that an induction channel from the Born contribution dominates the anomalous Hall current. This channel, which has long been overlooked in the literature, is due to the particle-hole asymmetry by nonlinear optical excitation. Finally, we study the case in the chiral p -wave superconducting state with a transverse conical magnetization, which breaks the Galilean invariance. In this situation, the intrinsic anomalous Hall conductivity is no longer zero. Comparison of this intrinsic channel with the extrinsic one from impurity scattering is addressed.
Anomalous Seebeck coefficient in boron carbides
International Nuclear Information System (INIS)
Aselage, T.L.; Emin, D.; Wood, C.; Mackinnon, I.D.R.; Howard, I.A.
1987-01-01
Boron carbides exhibit an anomalously large Seebeck coefficient with a temperature coefficient that is characteristic of polaronic hopping between inequivalent sites. The inequivalence in the sites is associated with disorder in the solid. The temperature dependence of the Seebeck coefficient for materials prepared by different techniques provides insight into the nature of the disorder
Examination of anomalous self-experience
DEFF Research Database (Denmark)
Raballo, Andrea; Parnas, Josef
2012-01-01
. Here, we present the initial normative data and psychometric properties of a newly developed instrument (Examination of Anomalous Self-experience [EASE]), specifically designed to support the psychopathological exploration of SDs in both research and "real world" clinical settings. Our results support...
Anomalous N=2 superconformal Ward identities
International Nuclear Information System (INIS)
Ketov, Sergei V.
2000-01-01
The N=2 superconformal Ward identities and their anomalies are discussed in N=2 superspace (including N=2 harmonic superspace), at the level of the low-energy effective action (LEEA) in four-dimensional N=2 supersymmetric field theories. The (first) chiral N=2 supergravity compensator is related to the known N=2 anomalous Ward identity in the N=2 (abelian) vector mulitplet sector. As regards the hypermultiplet LEEA given by the N=2 non-linear sigma-model (NLSM), a new anomalous N=2 superconformal Ward identity is found, whose existence is related to the (second) analytic compensator in N=2 supergravity. The celebrated solution of Seiberg and Witten is known to obey the (first) anomalous Ward identity in the Coulomb branch. We find a few solutions to the new anomalous Ward identity, after making certain assumptions about unbroken internal symmetries. Amongst the N=2 NLSM target space metrics governing the hypermultiplet LEEA are the SU(2)-Yang-Mills-Higgs monopole moduli-space metrics that can be encoded in terms of the spectral curves (Riemann surfaces), similarly to the Seiberg-Witten-type solutions. After a dimensional reduction to three spacetime dimensions (3d), our results support the mirror symmetry between the Coulomb and Higgs branches in 3d, N=4 gauge theories
Anomalous human behavior detection: An Adaptive approach
Leeuwen, C. van; Halma, A.; Schutte, K.
2013-01-01
Detection of anomalies (outliers or abnormal instances) is an important element in a range of applications such as fault, fraud, suspicious behavior detection and knowledge discovery. In this article we propose a new method for anomaly detection and performed tested its ability to detect anomalous
Anomalous VVH interactions at a linear collider
Indian Academy of Sciences (India)
Abstract. We examine, in a model independent way, the sensitivity of a linear collider to the couplings of a light Higgs boson to a pair of gauge bosons, including the possibility of. CP violation. We construct several observables that probe the various possible anomalous couplings. For an intermediate mass Higgs, a collider ...
Anomalous periodic disruptions in tokamak plasma
International Nuclear Information System (INIS)
Montvai, A.; Tegze, M.; Valyi, I.
1982-09-01
Anomalously strong, periodic instabilities were observed in the MT-1 tokamak. Characteristics of these instabilities were partly similar to those of internal disruptions, but there were features making them different from the normal relaxational oscillations. Basic characteristics of the phenomenon were studied with the aid of generally used diagnostics. (author)
Anomalous Hall effect in disordered multiband metals
Czech Academy of Sciences Publication Activity Database
Kovalev, A.A.; Sinova, Jairo; Tserkovnyak, Y.
2010-01-01
Roč. 105, č. 3 (2010), 036601/1-036601/4 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.621, year: 2010
Anomalous VVH interactions at a linear collider
Indian Academy of Sciences (India)
We examine, in a model independent way, the sensitivity of a linear collider to the couplings of a light Higgs boson to a pair of gauge bosons, including the possibility of CP violation. We construct several observables that probe the various possible anomalous couplings. For an intermediate mass Higgs, a collider operating ...
Anomalous Hall conductivity: Local orbitals approach
Czech Academy of Sciences Publication Activity Database
Středa, Pavel
2010-01-01
Roč. 82, č. 4 (2010), 045115/1-045115/9 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * Berry phase correction * orbital polarization momentum Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010
Bunburra Rockhole: A New Anomalous Achondrite
Czech Academy of Sciences Publication Activity Database
Bland, P.A.; Spurný, Pavel; Greenwood, R.C.; Towner, M.C.; Bevan, A.W.R.; Bottke jr., W.F.; Shrbený, Lukáš; McClafferty, T.; Vaughan, D.; Benedix, G.K.; Franchi, I.A.; Hough, R.M.
2009-01-01
Roč. 72, Supplement (2009), A34-A34 ISSN 1086-9379. [Annual Meeting of the Meteoritical Society /72./. Nancy, 13.06.2009-18.06.2009] Institutional research plan: CEZ:AV0Z10030501 Keywords : Bunburra Rockhole * anomalous achondrite Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.253, year: 2009
Anomalous Levinson theorem and supersymmetric quantum mechanics
International Nuclear Information System (INIS)
Boya, L.J.; Casahorran, J.; Esteve, J.G.
1993-01-01
We analyse the symmetry breaking associated to anomalous realization of supersymmetry in the context of SUSY QM. In this case one of the SUSY partners is singular; that leads to peculiar forms of the Levinson theorem relating phase shifts and bound states. Some examples are exhibited; peculiarities include negative energies, incomplete pairing of states and extra phases in scattering. (Author) 8 refs
Anomalous transport in turbulent plasmas and continuous time random walks
International Nuclear Information System (INIS)
Balescu, R.
1995-01-01
The possibility of a model of anomalous transport problems in a turbulent plasma by a purely stochastic process is investigated. The theory of continuous time random walks (CTRW's) is briefly reviewed. It is shown that a particular class, called the standard long tail CTRW's is of special interest for the description of subdiffusive transport. Its evolution is described by a non-Markovian diffusion equation that is constructed in such a way as to yield exact values for all the moments of the density profile. The concept of a CTRW model is compared to an exact solution of a simple test problem: transport of charged particles in a fluctuating magnetic field in the limit of infinite perpendicular correlation length. Although the well-known behavior of the mean square displacement proportional to t 1/2 is easily recovered, the exact density profile cannot be modeled by a CTRW. However, the quasilinear approximation of the kinetic equation has the form of a non-Markovian diffusion equation and can thus be generated by a CTRW
Physics basis of Multi-Mode anomalous transport module
Energy Technology Data Exchange (ETDEWEB)
Rafiq, T.; Kritz, A. H.; Luo, L. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Weiland, J. [Departments of Applied Physics, Chalmers University of Technology and Euratom-VR Assoc., S41296 Gothenburg (Sweden); Pankin, A. Y. [Tech-X Corporation, Boulder, Colorado (United States)
2013-03-15
The derivation of Multi-Mode anomalous transport module version 8.1 (MMM8.1) is presented. The MMM8.1 module is advanced, relative to MMM7.1, by the inclusion of peeling modes, dependence of turbulence correlation length on flow shear, electromagnetic effects in the toroidal momentum diffusivity, and the option to compute poloidal momentum diffusivity. The MMM8.1 model includes a model for ion temperature gradient, trapped electron, kinetic ballooning, peeling, collisionless and collision dominated magnetohydrodynamics modes as well as model for electron temperature gradient modes, and a model for drift resistive inertial ballooning modes. In the derivation of the MMM8.1 module, effects of collisions, fast ion and impurity dilution, non-circular flux surfaces, finite beta, and Shafranov shift are included. The MMM8.1 is used to compute thermal, particle, toroidal, and poloidal angular momentum transports. The fluid approach which underlies the derivation of MMM8.1 is expected to reliably predict, on an energy transport time scale, the evolution of temperature, density, and momentum profiles in plasma discharges for a wide range of plasma conditions.
Anomalous high-frequency wave activity flux preceding anomalous changes in the Northern polar jet
Nakamura, Mototaka; Kadota, Minoru; Yamane, Shozo
2010-05-01
Anomalous forcing by quasi-geostrophic (QG) waves has been reported as an important forcing factor in the Northern Annular Mode (NAM) in recent literatures. In order to shed a light on the dynamics of the NAM from a different angle, we have examined anomalous behavior of the winter jets in the upper troposphere and stratosphere by focusing our diagnosis on not the anomalous geopotential height (Z) itself, but on the anomalous change in the Z (dZ) between two successive months and preceding transient QG wave activity flux during the cold season. We calculated EOFs of dZ between two successive months at 150hPa for a 46-year period, from 1958 to 2003, using the monthly mean NCEP reanalysis data. We then formed anomaly composites of changes in Z and the zonal velocity (U), as well as the preceding and following wave activity flux, Z, U, and temperature at various heights, for both positive and negative phases of the first EOF. For the wave forcing fields, we adopted the diagnostic system for the three-dimensional QG transient wave activity flux in the zonally-varying three-dimensional mean flow developed by Plumb (1986) with a slight modification in its application to the data. Our choice of the Plumb86 is based on the fact that the winter mean flow in the Northern Hemisphere is characterized by noticeable zonal asymmetry, and has a symbiotic relationship with waves in the extra-tropics. The Plumb86 flux was calculated for high-frequency (period of 2 to 7 days) and low-frequency (period of 10 to 20 days) waves with the ultra-low-frequency (period of 30 days or longer) flow as the reference state for each time frame of the 6 hourly NCEP reanalysis data from 1958 to 2003. By replacing the mean flow with the ultra-low-frequency flow in the application of the Plumb86 formula, the flux fields were calculated as time series at 6 hour intervals. The time series of the wave activity flux was then averaged for each month. The patterns of composited anomalous dZ and dU clearly
Huberman, Lori B; Murray, Andrew W
2014-01-01
Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells.
Huberman, Lori B.; Murray, Andrew W.
2014-01-01
Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells. PMID:25329559
International Nuclear Information System (INIS)
Testylier, Guy; Lahrech, Hana; Montigon, Olivier; Foquin, Annie; Delacour, Claire; Bernabe, Denis; Segebarth, Christoph; Dorandeu, Frederic; Carpentier, Pierre
2007-01-01
Purpose: In the present study, diffusion-weighted magnetic resonance imaging (DW-MRI) and histology were used to assess cerebral edema and lesions in mice intoxicated by a convulsive dose of soman, an organophosphate compound acting as an irreversible cholinesterase inhibitor. Methods: Three hours and 24 h after the intoxication with soman (172 μg/kg), the mice were anesthetized with an isoflurane/N 2 O mixture and their brain examined with DW-MRI. After the imaging sessions, the mice were sacrificed for histological analysis of their brain. Results: A decrease in the apparent diffusion coefficient (ADC) was detected as soon as 3 h after the intoxication and was found strongly enhanced at 24 h. A correlation was obtained between the ADC change and the severity of the overall brain damage (edema and cellular degeneration): the more severe the damage, the stronger the ADC drop. Anesthesia was shown to interrupt soman-induced seizures and to attenuate edema and cell change in certain sensitive brain areas. Finally, brain water content was assessed using the traditional dry/wet weight method. A significant increase of brain water was observed following the intoxication. Conclusions: The ADC decrease observed in the present study suggests that brain edema in soman poisoning is mainly intracellular and cytotoxic. Since entry of water into Brain was also evidenced, this type of edema is certainly mixed with others (vasogenic, hydrostatic, osmotic). The present study confirms the potential of DW-MRI as a non-invasive tool for monitoring the acute neuropathological consequences (edema and neurodegeneration) of soman-induced seizures
Improved formulas for trapped-ion anomalous transport in tokamaks without and with shear
International Nuclear Information System (INIS)
Sardei, F.; Wimmel, H.K.
1980-12-01
More refined numerical calculations of trapped-ion anomalous transport in a 2-D slab, trapped-fluid model suggest an anomalous diffusion coefficient D approx. 3.5 x 10 -2 delta 0 a 2 νsub(i)sup(e)sup(f)sup(f) for a tokamak plasma without shear. This supersedes earlier results. The new formula is independently confirmed by two different analytical calculations. One of them uses a similarity analysis of unabridged Kadomtsev-Pogutse-type trapped-fluid equations and the multiperiodic spatial structure of the saturated trapped-ion wave found in both the earlier and the recent numerical calculations. The other calculation yields a class of exact nonlinear solutions of the trapped-fluid equations. The new shearless result is used to derive the anomalous diffusion with shear effect by a method described in an earlier paper. The new transport formulas have been numerically evaluated for several tokamaks in an IPP report, where the results are shown in graph form. (orig.)
Anomalous quantum numbers and topological properties of field theories
International Nuclear Information System (INIS)
Polychronakos, A.P.
1987-01-01
We examine the connection between anomalous quantum numbers, symmetry breaking patterns and topological properties of some field theories. The main results are the following: In three dimensions the vacuum in the presence of abelian magnetic field configurations behaves like a superconductor. Its quantum numbers are exactly calculable and are connected with the Atiyah-Patodi-Singer index theorem. Boundary conditions, however, play a nontrivial role in this case. Local conditions were found to be physically preferable than the usual global ones. Due to topological reasons, only theories for which the gauge invariant photon mass in three dimensions obeys a quantization condition can support states of nonzero magnetic flux. For similar reasons, this mass induces anomalous angular momentum quantum numbers to the states of the theory. Parity invariance and global flavor symmetry were shown to be incompatible in such theories. In the presence of mass less flavored fermions, parity will always break for an odd number of fermion flavors, while for even fermion flavors it may not break but only at the expense of maximally breaking the flavor symmetry. Finally, a connection between these theories and the quantum Hall effect was indicated
Directory of Open Access Journals (Sweden)
Béatrice Skiöld
Full Text Available BACKGROUND AND AIM: High tidal volume (VT ventilation during resuscitation of preterm lambs results in brain injury evident histologically within hours after birth. We aimed to investigate whether magnetic resonance spectroscopy (MRS and/or diffusion tensor imaging (DTI can be used for early in vivo detection of ventilation-induced brain injury in preterm lambs. METHODS: Newborn lambs (0.85 gestation were stabilized with a "protective ventilation" strategy (PROT, n = 7: prophylactic Curosurf, sustained inflation, VT 7 mL/kg, positive end expiratory pressure (PEEP 5 cmH2O or an initial 15 minutes of "injurious ventilation" (INJ, n = 10: VT 12 mL/kg, no PEEP, late Curosurf followed by PROT ventilation for the remainder of the experiment. At 1 hour, lambs underwent structural magnetic resonance imaging (Siemens, 3 Tesla. For measures of mean/axial/radial diffusivity (MD, AD, RD and fractional anisotropy (FA, 30 direction DTI was performed. Regions of interests encompassed the thalamus, internal capsule, periventricular white matter and the cerebellar vermis. MRS was performed using a localized single-voxel (15×15×20 mm3, echo time 270 ms encompassing suptratentorial deep nuclear grey matter and central white matter. Peak-area ratios for lactate (Lac relative to N-acetylaspartate (NAA, choline (Cho and creatine (Cr were calculated. Groups were compared using 2-way RM-ANOVA, Mann-Whitney U-test and Spearman's correlations. RESULTS: No cerebral injury was seen on structural MR images. Lambs in the INJ group had higher mean FA and lower mean RD in the thalamus compared to PROT lambs, but not in the other regions of interest. Peak-area lactate ratios >1.0 was only seen in INJ lambs. A trend of higher mean peak-area ratios for Lac/Cr and Lac/Cho was seen, which correlated with lower pH in both groups. CONCLUSION: Acute changes in brain diffusion measures and metabolite peak-area ratios were observed after injurious ventilation. Early MRS/DTI is
Directory of Open Access Journals (Sweden)
Natalie Zeytuni
Full Text Available Cation diffusion facilitators (CDF are part of a highly conserved protein family that maintains cellular divalent cation homeostasis in all domains of life. CDF's were shown to be involved in several human diseases, such as Type-II diabetes and neurodegenerative diseases. In this work, we employed a multi-disciplinary approach to study the activation mechanism of the CDF protein family. For this we used MamM, one of the main ion transporters of magnetosomes--bacterial organelles that enable magnetotactic bacteria to orientate along geomagnetic fields. Our results reveal that the cytosolic domain of MamM forms a stable dimer that undergoes distinct conformational changes upon divalent cation binding. MamM conformational change is associated with three metal binding sites that were identified and characterized. Altogether, our results provide a novel auto-regulation mode of action model in which the cytosolic domain's conformational changes upon ligand binding allows the priming of the CDF into its transport mode.
Dadgar, Sina; Rodríguez Troncoso, Joel; Rajaram, Narasimhan
2018-02-01
Currently, anatomical assessment of tumor volume performed several weeks after completion of treatment is the clinical standard to determine whether a cancer patient has responded to a treatment. However, functional changes within the tumor could potentially provide information regarding treatment resistance or response much earlier than anatomical changes. We have used diffuse reflectance spectroscopy to assess the short and long-term re-oxygenation kinetics of a human head and neck squamous cell carcinoma xenografts in response to radiation therapy. First, we injected UM-SCC-22B cell line into the flank of 50 mice to grow xenografts. Once the tumor volume reached 200 mm3 (designated as Day 1), the mice were distributed into radiation and control groups. Members of radiation group underwent a clinical dose of radiation of 2 Gy/day on Days 1, 4, 7, and 10 for a cumulative dose of 8 Gy. DRS spectra of these tumors were collected for 14 days during and after therapy, and the collected spectra of each tumor were converted to its optical properties using a lookup table-base inverse model. We found statistically significant differences in tumor growth rate between two groups which is in indication of the sensitivity of this cell line to radiation. We further acquired significantly different contents of hemoglobin and scattering magnitude and size in two groups. The scattering has previously been associated with necrosis. We furthermore found significantly different time-dependent changes in vascular oxygenation and tumor hemoglobin concentration in post-radiation days.
Directory of Open Access Journals (Sweden)
Ryan C Thompson
Full Text Available BACKGROUND: Diffuse large B-cell lymphoma (DLBCL is a genetically heterogeneous disease and this variation can often be used to explain the response of individual patients to chemotherapy. One cancer therapeutic approach currently in clinical trials uses histone deacetylase inhibitors (HDACi's as monotherapy or in combination with other agents. METHODOLOGY/PRINCIPAL FINDINGS: We have used a variety of cell-based and molecular/biochemical assays to show that two pan-HDAC inhibitors, trichostatin A and vorinostat, induce apoptosis in seven of eight human DLBCL cell lines. Consistent with previous reports implicating the BCL-2 family in regulating HDACi-induced apoptosis, ectopic over-expression of anti-apoptotic proteins BCL-2 and BCL-XL or pro-apoptotic protein BIM in these cell lines conferred further resistance or sensitivity, respectively, to HDACi treatment. Additionally, BCL-2 family antgonist ABT-737 increased the sensitivity of several DLBCL cell lines to vorinostat-induced apoptosis, including one cell line (SUDHL6 that is resistant to vorinostat alone. Moreover, two variants of the HDACi-sensitive SUDHL4 cell line that have decreased sensitivity to vorinostat showed up-regulation of BCL-2 family anti-apoptotic proteins such as BCL-XL and MCL-1, as well as decreased sensitivity to ABT-737. These results suggest that the regulation and overall balance of anti- to pro-apoptotic BCL-2 family protein expression is important in defining the sensitivity of DLBCL to HDACi-induced apoptosis. However, the sensitivity of DLBCL cell lines to HDACi treatment does not correlate with expression of any individual BCL-2 family member. CONCLUSIONS/SIGNIFICANCE: These studies indicate that the sensitivity of DLBCL to treatment with HDACi's is dependent on the complex regulation of BCL-2 family members and that BCL-2 antagonists may enhance the response of a subset of DLBCL patients to HDACi treatment.
Enhancing Rotational Diffusion Using Oscillatory Shear
Leahy, Brian D.; Cheng, Xiang; Ong, Desmond C.; Liddell-Watson, Chekesha; Cohen, Itai
2013-01-01
Taylor dispersion - shear-induced enhancement of translational diffusion - is an important phenomenon with applications ranging from pharmacology to geology. Through experiments and simulations, we show that rotational diffusion is also enhanced
Inference of protein diffusion probed via fluorescence correlation spectroscopy
Tsekouras, Konstantinos
2015-03-01
Fluctuations are an inherent part of single molecule or few particle biophysical data sets. Traditionally, ``noise'' fluctuations have been viewed as a nuisance, to be eliminated or minimized. Here we look on how statistical inference methods - that take explicit advantage of fluctuations - have allowed us to draw an unexpected picture of single molecule diffusional dynamics. Our focus is on the diffusion of proteins probed using fluorescence correlation spectroscopy (FCS). First, we discuss how - in collaboration with the Bustamante and Marqusee labs at UC Berkeley - we determined using FCS data that individual enzymes are perturbed by self-generated catalytic heat (Riedel et al, Nature, 2014). Using the tools of inference, we found how distributions of enzyme diffusion coefficients shift in the presence of substrate revealing that enzymes performing highly exothermic reactions dissipate heat by transiently accelerating their center of mass following a catalytic reaction. Next, when molecules diffuse in the cell nucleus they often appear to diffuse anomalously. We analyze FCS data - in collaboration with Rich Day at the IU Med School - to propose a simple model for transcription factor binding-unbinding in the nucleus to show that it may give rise to apparent anomalous diffusion. Here inference methods extract entire binding affinity distributions for the diffusing transcription factors, allowing us to precisely characterize their interactions with different components of the nuclear environment. From this analysis, we draw key mechanistic insight that goes beyond what is possible by simply fitting data to ``anomalous diffusion'' models.
International Nuclear Information System (INIS)
Sen, A.K.
1998-01-01
This final report is comprised of the following six progress reports: Ion Temperature Gradient Instability and Anomalous Transport, July 1989; Ion Temperature Gradient Instability and Anomalous Transport, August 1991; Ion Temperature Gradient Instability and Anomalous Transport, July 1993; Ion Anomalous Transport and Feedback Control, May 1994; Ion Anomalous Transport and Feedback Control, April 1995; and Ion Anomalous Transport and Feedback Control, December 1997
International Nuclear Information System (INIS)
Carlen, E.A.
1984-01-01
In Nelson's stochastic mechanics, quantum phenomena are described in terms of diffusions instead of wave functions. These diffusions are formally given by stochastic differential equations with extremely singular coefficients. Using PDE methods, we prove the existence of solutions. This reult provides a rigorous basis for stochastic mechanics. (orig.)
Feynman-Kac equations for reaction and diffusion processes
Hou, Ru; Deng, Weihua
2018-04-01
This paper provides a theoretical framework for deriving the forward and backward Feynman-Kac equations for the distribution of functionals of the path of a particle undergoing both diffusion and reaction processes. Once given the diffusion type and reaction rate, a specific forward or backward Feynman-Kac equation can be obtained. The results in this paper include those for normal/anomalous diffusions and reactions with linear/nonlinear rates. Using the derived equations, we apply our findings to compute some physical (experimentally measurable) statistics, including the occupation time in half-space, the first passage time, and the occupation time in half-interval with an absorbing or reflecting boundary, for the physical system with anomalous diffusion and spontaneous evanescence.
Resurgence of the cusp anomalous dimension
Energy Technology Data Exchange (ETDEWEB)
Dorigoni, Daniele; Hatsuda, Yasuyuki [DESY Theory Group, DESY Hamburg,Notkestrasse 85, D-22603 Hamburg (Germany)
2015-09-21
We revisit the strong coupling limit of the cusp anomalous dimension in planar N=4 super Yang-Mills theory. It is known that the strong coupling expansion is asymptotic and non-Borel summable. As a consequence, the cusp anomalous dimension receives non-perturbative corrections, and the complete strong coupling expansion should be a resurgent transseries. We reveal that the perturbative and non-perturbative parts in the transseries are closely interrelated. Solving the Beisert-Eden-Staudacher equation systematically, we analyze in detail the large order behavior in the strong coupling perturbative expansion and show that the non-perturbative information is indeed encoded there. An ambiguity of (lateral) Borel resummations of the perturbative expansion is precisely canceled by the contributions from the non-perturbative sectors, and the final result is real and unambiguous.
Resurgence of the Cusp Anomalous Dimension
Energy Technology Data Exchange (ETDEWEB)
Dorigoni, Daniele; Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group
2015-06-15
We revisit the strong coupling limit of the cusp anomalous dimension in planar N=4 super Yang-Mills theory. It is known that the strong coupling expansion is asymptotic and non-Borel summable. As a consequence, the cusp anomalous dimension receives non-perturbative corrections, and the complete strong coupling expansion should be a resurgent transseries. We reveal that the perturbative and non-perturbative parts in the transseries are closely interrelated. Solving the Beisert-Eden-Staudacher equation systematically, we analyze in detail the large order behavior in the strong coupling perturbative expansion and show that the non-perturbative information is indeed encoded there. An ambiguity of (lateral) Borel resummations of the perturbative expansion is precisely canceled by the contributions from the non-perturbative sectors, and the final result is real and unambiguous.
Resurgence of the Cusp Anomalous Dimension
International Nuclear Information System (INIS)
Dorigoni, Daniele; Hatsuda, Yasuyuki
2015-06-01
We revisit the strong coupling limit of the cusp anomalous dimension in planar N=4 super Yang-Mills theory. It is known that the strong coupling expansion is asymptotic and non-Borel summable. As a consequence, the cusp anomalous dimension receives non-perturbative corrections, and the complete strong coupling expansion should be a resurgent transseries. We reveal that the perturbative and non-perturbative parts in the transseries are closely interrelated. Solving the Beisert-Eden-Staudacher equation systematically, we analyze in detail the large order behavior in the strong coupling perturbative expansion and show that the non-perturbative information is indeed encoded there. An ambiguity of (lateral) Borel resummations of the perturbative expansion is precisely canceled by the contributions from the non-perturbative sectors, and the final result is real and unambiguous.
Anomalous properties of hot dense nonequilibrium plasmas
International Nuclear Information System (INIS)
Ferrante, G; Zarcone, M; Uryupin, S A
2005-01-01
A concise overview of a number of anomalous properties of hot dense nonequilibrium plasmas is given. The possibility of quasistationary megagauss magnetic field generation due to Weibel instability is discussed for plasmas created in atom tunnel ionization. The collisionless absorption and reflection of a test electromagnetic wave normally impinging on the plasma with two-temperature bi-maxwellian electron velocity distribution function are studied. Due to the wave magnetic field influence on the electron kinetics in the skin layer the wave absorption and reflection significantly depend on the degree of the electron temperature anisotropy. The linearly polarized impinging wave during reflection transforms into an elliptically polarized one. The problem of transmission of an ultrashort laser pulse through a layer of dense plasma, formed as a result of ionization of a thin foil, is considered. It is shown that the strong photoelectron distribution anisotropy yields an anomalous penetration of the wave field through the foil
Anomalous enthalpy relaxation in vitreous silica
DEFF Research Database (Denmark)
Yue, Yuanzheng
2015-01-01
scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....
I.C. van den Bos (Indra); S.M. Hussain (Shahid); G.P. Krestin (Gabriel); P.A. Wielopolski (Piotr)
2008-01-01
textabstractInstitutional Review Board approval and signed informed consent were obtained by all participants for an ongoing sequence optimization project at 3.0 T. The purpose of this study was to evaluate breath-hold diffusion-induced blackblood echo-planar imaging (BBEPI) as a potential
Unfair and Anomalous Evolutionary Dynamics from Fluctuating Payoffs
Stollmeier, Frank; Nagler, Jan
2018-02-01
Evolution occurs in populations of reproducing individuals. Reproduction depends on the payoff a strategy receives. The payoff depends on the environment that may change over time, on intrinsic uncertainties, and on other sources of randomness. These temporal variations in the payoffs can affect which traits evolve. Understanding evolutionary game dynamics that are affected by varying payoffs remains difficult. Here we study the impact of arbitrary amplitudes and covariances of temporally varying payoffs on the dynamics. The evolutionary dynamics may be "unfair," meaning that, on average, two coexisting strategies may persistently receive different payoffs. This mechanism can induce an anomalous coexistence of cooperators and defectors in the prisoner's dilemma, and an unexpected selection reversal in the hawk-dove game.
Anomalous friction of graphene nanoribbons on waved graphenes
Directory of Open Access Journals (Sweden)
Jun Fang
2015-11-01
Full Text Available Friction plays a critical role in the function and maintenance of small-scale structures, where the conventional Coulomb friction law often fails. To probe the friction at small scales, here we present a molecular dynamics study on the process of dragging graphene nanoribbons on waved graphene substrates. The simulation shows that the induced friction on graphene with zero waviness is ultra-low and closely related to the surface energy barrier. On waved graphenes, the friction generally increases with the amplitude of the wave at a fixed period, but anomalously increases and then decreases with the period at a fixed amplitude. These findings provide insights into the ultra-low friction at small scales, as well as some guidelines into the fabrication of graphene-based nano-composites with high performance.
Analysis of the anomalous hydrogen solubilities in deformed palladiums
Energy Technology Data Exchange (ETDEWEB)
Park, Choong Nyeon; Lee, Ho Jong
1987-02-01
The anomalous hydrogen solubilities in the deformed palladiums were analyzed by empolying modified Kirchheim's model with considering the partially coherent strain energy which would induced during hydride precipitation around edge dislocations. The dislocation densities, obtained by this model, of the various cold worked and/or reversible US transformed palladium samples were the order of 10/sup 11/cm/sup -2/. The partially coherent strain energies were about 3 kJ/molH and nearly same in the various samples. This value could be compared with the incoherent strain energy, 0.4kJ/molH, which was obtained from the hysteresis on P-C isotherm, and the coherent strain energy calulated, 9.6kJ/molH.
What's wrong with anomalous chiral gauge theory?
International Nuclear Information System (INIS)
Kieu, T.D.
1994-05-01
It is argued on general ground and demonstrated in the particular example of the Chiral Schwinger Model that there is nothing wrong with apparently anomalous chiral gauge theory. If quantised correctly, there should be no gauge anomaly and chiral gauge theory should be renormalisable and unitary, even in higher dimensions and with non-Abelian gauge groups. Furthermore, it is claimed that mass terms for gauge bosons and chiral fermions can be generated without spoiling the gauge invariance. 19 refs
Anomalous Symmetry Fractionalization and Surface Topological Order
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Xie Chen
2015-10-01
Full Text Available In addition to possessing fractional statistics, anyon excitations of a 2D topologically ordered state can realize symmetry in distinct ways, leading to a variety of symmetry-enriched topological (SET phases. While the symmetry fractionalization must be consistent with the fusion and braiding rules of the anyons, not all ostensibly consistent symmetry fractionalizations can be realized in 2D systems. Instead, certain “anomalous” SETs can only occur on the surface of a 3D symmetry-protected topological (SPT phase. In this paper, we describe a procedure for determining whether a SET of a discrete, on-site, unitary symmetry group G is anomalous or not. The basic idea is to gauge the symmetry and expose the anomaly as an obstruction to a consistent topological theory combining both the original anyons and the gauge fluxes. Utilizing a result of Etingof, Nikshych, and Ostrik, we point out that a class of obstructions is captured by the fourth cohomology group H^{4}(G,U(1, which also precisely labels the set of 3D SPT phases, with symmetry group G. An explicit procedure for calculating the cohomology data from a SET is given, with the corresponding physical intuition explained. We thus establish a general bulk-boundary correspondence between the anomalous SET and the 3D bulk SPT whose surface termination realizes it. We illustrate this idea using the chiral spin liquid [U(1_{2}] topological order with a reduced symmetry Z_{2}×Z_{2}⊂SO(3, which can act on the semion quasiparticle in an anomalous way. We construct exactly solved 3D SPT models realizing the anomalous surface terminations and demonstrate that they are nontrivial by computing three-loop braiding statistics. Possible extensions to antiunitary symmetries are also discussed.
Micro-instabilities and anomalous transport
International Nuclear Information System (INIS)
Connor, J.W.
1992-01-01
In order to optimise the design of a tokamak fusion reactor it is necessary to understand how the energy confinement time depends on the plasma and machine parameters. In principle the neo-classical theory provides this information but empirical evidence yields confinement times up to two orders of magnitude less than the predictions of this model. Experimental evidence of microscopic fluctuations in plasma density and other quantities suggests turbulent electro-magnetic fluctuations may be responsible for this anomalous transport. (Author)
Anomalous cross-modulation between microwave beams
Ranfagni, Anedio; Mugnai, Daniela; Petrucci, Andrea; Mignani, Roberto; Cacciari, Ilaria
2018-06-01
An anomalous effect in the near field of crossing microwave beams, which consists of an unexpected transfer of modulation from one beam to the other, has found a plausible interpretation within the framework of a locally broken Lorentz invariance. A theoretical approach of this kind deserves to be reconsidered also in the light of further experimental work, including a counter-check of the phenomenon.
Anomalous hall effect in ferromagnetic semiconductors
Czech Academy of Sciences Publication Activity Database
Jungwirth, Tomáš; Niu, Q.; MacDonald, A. H.
2002-01-01
Roč. 88, č. 20 (2002), s. 207208-1-207208-4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0912; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * anomalous Hall effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.323, year: 2002
Probing anomalous gauge boson couplings at LEP
International Nuclear Information System (INIS)
Dawson, S.; Valencia, G.
1994-01-01
We bound anomalous gauge boson couplings using LEP data for the Z → bar ∫∫ partial widths. We use an effective field theory formalism to compute the one-loop corrections resulting from non-standard model three and four gauge boson vertices. We find that measurements at LEP constrain the three gauge boson couplings at a level comparable to that obtainable at LEPII
Islam, Shariful; Qi, Wenqing; Morales, Carla; Cooke, Laurence; Spier, Catherine; Weterings, Eric; Mahadevan, Daruka
2017-10-01
Double hit (DH) or double expressor (DE) diffuse large B-cell lymphomas (DLBCL) are aggressive non-Hodgkin's lymphomas (NHL) with translocations and/or overexpressions of MYC and BCL-2 , which are difficult to treat. Aurora kinase (AK) inhibition with alisertib in DH/DE-DLBCL induces cell death in ∼30%, while ∼70% are aneuploid and senescent cells (AASC), a mitotic escape mechanism contributing to drug resistance. These AASCs elaborated a high metabolic rate by increased AKT/mTOR and ERK/MAPK activity via BTK signaling through the chronic active B-cell receptor (BCR) pathway. Combinations of alisertib + ibrutinib or alisertib + ibrutinib + rituximab significantly reduced AASCs with enhanced intrinsic cell death. Inhibition of AK + BTK reduced phosphorylation of AKT/mTOR and ERK-1/2, upregulated phospho-H2A-X and Chk-2 (DNA damage), reduced Bcl-6, and decreased Bcl-2 and Bcl-xL and induced apoptosis by PARP cleavage. In a DE-DLBCL SCID mouse xenograft model, ibrutinib alone was inactive, while alisertib + ibrutinib was additive with a tumor growth inhibition (TGI) rate of ∼25%. However, TGI for ibrutinib + rituximab was ∼50% to 60%. In contrast, triple therapy showed a TGI rate of >90%. Kaplan-Meier survival analysis showed that 67% of mice were alive at day 89 with triple therapy versus 20% with ibrutinib + rituximab. All treatments were well tolerated with no changes in body weights. A novel triple therapy consisting of alisertib + ibrutinib + rituximab inhibits AASCs induced by AK inhibition in DH/DE-DLBCL leading to a significant antiproliferative signal, enhanced intrinsic apoptosis and may be of therapeutic potential in these lymphomas. Mol Cancer Ther; 16(10); 2083-93. ©2017 AACR . ©2017 American Association for Cancer Research.
Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T
2014-03-01
Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe. Copyright © 2013 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Edwards, Tanya
2017-01-18
A fundamental issue in ground-based gamma-ray astronomy is the identification of γ-ray events among the overwhelming background of air showers induced by charged cosmic rays. Reconstruction techniques exist to distinguish most of the background of hadrons but an irreducible background of electrons and gamma-like protons still remain. I present here a new technique making use of high-altitude Cherenkov light emitted by the charged primary particle and air shower development properties. This method provides a way to distinguish between electrons and gamma rays on a statistical basis. In addition to this, the remaining proton background can also be identified. The technique was developed, tested and applied to studies using the High Energy Stereoscopic System (H.E.S.S.) located in Namibia. The analysis method is especially important in the detection of diffuse signals and eliminates the necessity of a background region in the field of view. The technique was applied to three scientific studies. The latitude profile of the Galactic diffuse γ-ray emission was analysed. A width of σ=0.25±0.05 (0.20±0.06 ) for energies of 380 to 900 GeV(1 to 6 TeV) was determined. The cosmic electron spectrum was measured between 0.38 and 14 TeV and a broken power law was fit to the data. The spectrum steepens from Γ=3.08±0.06 to Γ=3.72±0.12 at a break in energy of 1.11±0.04 TeV. In addition, upper limits on the maximum γ-ray contamination from the Isotropic γ-Ray Background was placed at 4 x 10{sup -3}(5 x 10{sup -3}) MeVcm{sup -2}s{sup -1}sr{sup -1} for energies of 1 to 6 TeV(380 to 900 GeV).
Multislice CT imaging of anomalous coronary arteries
International Nuclear Information System (INIS)
Shi Heshui; Aschoff, Andrik J.; Brambs, Hans-Juergen; Hoffmann, Martin H.K.
2004-01-01
The purpose of the present study was to evaluate the role of 16 multislice computed tomography (MSCT) to identify the origin of anomalous coronary arteries and to confirm their anatomic course in relation to the great vessels. Accuracy of coronary artery disease (CAD) detection was a secondary aim and was tested with conventional angiograms (CA) serving as standard of reference. Two hundred and forty-two consecutive patients referred for noninvasive coronary CT imaging were reviewed for the study. Sixteen patients (6.6%) with anomalous coronary arteries were detected and included as the study group. MSCT and CA images were analyzed in a blinded fashion for accuracy of anomalous artery origin and path detection. Results were compared in a secondary consensus evaluation. Accuracy ratios to detect CAD with MSCT in all vessels were calculated. Coronary anomalies for all 16 patients were correctly displayed on MSCT. CA alone achieved correct identification of the abnormality in only 53% (P=0.016). Sensitivity and specificity of MSCT to detect significantly stenosed vessels was 90 and 92%. 16-MSCT is accurate to delineate abnormally branching coronary arteries and allows sufficiently accurate detection of obstructive coronary artery disease in distal branches. It should therefore be considered as a prime non-invasive imaging tool for suspected coronary anomalies. (orig.)
The Anomalous Magnetic Moment of the Muon
Jegerlehner, Friedrich
2008-01-01
This book reviews the present state of knowledge of the anomalous magnetic moment a=(g-2)/2 of the muon. The muon anomalous magnetic moment amy is one of the most precisely measured quantities in elementary particle physics and provides one of the most stringent tests of relativistic quantum field theory as a fundamental theoretical framework. It allows for an extremely precise check of the standard model of elementary particles and of its limitations. Recent experiments at the Brookhaven National Laboratory now reach the unbelievable precision of 0.5 parts per million, improving the accuracy of previous g-2 experiments at CERN by a factor of 14. A major part of the book is devoted to the theory of the anomalous magnetic moment and to estimates of the theoretical uncertainties. Quantum electrodynamics and electroweak and hadronic effects are reviewed. Since non-perturbative hadronic effects play a key role for the precision test, their evaluation is described in detail. After the overview of theory, the exper...
Anomalous dissolution of metals and chemical corrosion
Directory of Open Access Journals (Sweden)
DRAGUTIN M. DRAZIC
2005-03-01
Full Text Available An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recognizable by the fact that during anodic dissolutionmore material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas bubble blocking, hydrogen embrittlement, passive layer cracking and other possible reasons for such behavior have been discussed. It was shown, as suggested by Kolotyrkin and coworkers, that the reason can be, also, the chemical reaction in which H2O molecules with the metal form metal ions and gaseous H2 in a potential independent process. It occurs simultaneously with the electrochemical corrosion process, but the electrochemical process controls the corrosion potential. On the example of Cr in acid solution itwas shown that the reason for the anomalous behavior is dominantly chemical dissolution, which is considerably faster than the electrochemical corrosion, and that the increasing temperature favors chemical reaction, while the other possible reasons for the anomalous behavior are of negligible effect. This effect is much smaller in the case of Fe, but exists. The possible role of the chemical dissolution reacton and hydrogen evolution during pitting of steels and Al and stress corrosion cracking or corrosion fatigue are discussed.
Fractional diffusion equation for heterogeneous medium
International Nuclear Information System (INIS)
Polo L, M. A.; Espinosa M, E. G.; Espinosa P, G.; Del Valle G, E.
2011-11-01
The asymptotic diffusion approximation for the Boltzmann (transport) equation was developed in 1950 decade in order to describe the diffusion of a particle in an isotropic medium, considers that the particles have a diffusion infinite velocity. In this work is developed a new approximation where is considered that the particles have a finite velocity, with this model is possible to describe the behavior in an anomalous medium. According with these ideas the model was obtained from the Fick law, where is considered that the temporal term of the current vector is not negligible. As a result the diffusion equation of fractional order which describes the dispersion of particles in a highly heterogeneous or disturbed medium is obtained, i.e., in a general medium. (Author)
Ekmark-Lewén, Sara; Flygt, Johanna; Fridgeirsdottir, Gudrun A; Kiwanuka, Olivia; Hånell, Anders; Meyerson, Bengt J; Mir, Anis K; Gram, Hermann; Lewén, Anders; Clausen, Fredrik; Hillered, Lars; Marklund, Niklas
2016-04-01
Widespread traumatic axonal injury (TAI) results in brain network dysfunction, which commonly leads to persisting cognitive and behavioural impairments following traumatic brain injury (TBI). TBI induces a complex neuroinflammatory response, frequently located at sites of axonal pathology. The role of the pro-inflammatory cytokine interleukin (IL)-1β has not been established in TAI. An IL-1β-neutralizing or a control antibody was administered intraperitoneally at 30 min following central fluid percussion injury (cFPI), a mouse model of widespread TAI. Mice subjected to moderate cFPI (n = 41) were compared with sham-injured controls (n = 20) and untreated, naive mice (n = 9). The anti-IL-1β antibody reached the target brain regions in adequate therapeutic concentrations (up to ~30 μg/brain tissue) at 24 h post-injury in both cFPI (n = 5) and sham-injured (n = 3) mice, with lower concentrations at 72 h post-injury (up to ~18 μg/g brain tissue in three cFPI mice). Functional outcome was analysed with the multivariate concentric square field (MCSF) test at 2 and 9 days post-injury, and the Morris water maze (MWM) at 14-21 days post-injury. Following TAI, the IL-1β-neutralizing antibody resulted in an improved behavioural outcome, including normalized behavioural profiles in the MCSF test. The performance in the MWM probe (memory) trial was improved, although not in the learning trials. The IL-1β-neutralizing treatment did not influence cerebral ventricle size or the number of microglia/macrophages. These findings support the hypothesis that IL-1β is an important contributor to the processes causing complex cognitive and behavioural disturbances following TAI. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
International Nuclear Information System (INIS)
Frontier, J.P.
1987-08-01
A contribution of the study of the capacities of Particle Induced X-ray Emission (P.I.X.E.) for depth profiling, in the range of 1 to 10 micrometers and over, is presented here. It is shown that, in a non destructuve way, the concentration profile of a given element can be obtained, in principle, by deconvoluting the X-ray yields of this element, measured in a set of experiments in which the energy of the impinging protons, hence their range, is systematically varied. Direct deconvolution procedure, which leads to the inversion of an ill-conditionned matrix is unsuitable. So we generalized the iterative procedure previously used by Vegh to solve a similar problem. Alternatively we also used a fitting procedure of several parameters which gave us somewhat better than those of the iterative procedure. Both algorithms where applied to a set of X-ray yields induced by protons of energy between 0.45 to 2 MeV, corresponding to the first 6 micrometers of various depletion profiles of zinc in an initially homogeneous Ag-3 at % Zn annealed under vacuum. For investigation of deeper layers, a sectionning technique which consists in analysing thin film hydroxide targets by specific chemistry of tiny turning, was developped with success. Cross-reference of all the obtained profiles was made with electron microprobe determination on transverse section, and with the predictions of the theory of atomic diffusion. In addition, the possibilities of increasing the depth resolution by developping techniques either of controled sanding of the surface, or analysis of the sample is discussed [fr
Enhancement of perpendicular magnetic anisotropy and anomalous hall effect in Co/Ni multilayers
Energy Technology Data Exchange (ETDEWEB)
Liu, Yiwei; Zhang, Jingyan, E-mail: jyzhang@ustb.edu.cn; Jiang, Shaolong; Liu, Qianqian; Li, Xujing; Yu, Guanghua, E-mail: ghyu@mater.ustb.edu.cn
2016-12-15
The perpendicular magnetic anisotropy (PMA) and the anomalous Hall effect (AHE) in Co/Ni multilayer were optimized by manipulating its interface structure (inducing HfO{sub 2} capping layer and Pt insertion) and post-annealing treatment. A strong PMA can be obtained in Co/Ni multilayers with HfO{sub 2} capping layer even after annealing at 400 °C. The heavy metal Hf may improve the interfacial spin-orbit coupling, which responsible for the enhanced PMA and high annealing stability. Moreover, the multilayer containing HfO{sub 2} capping layer also exhibited high saturation anomalous Hall resistivity through post-annealing, which is 0.85 μΩ cm after annealing at 375 °C, 211% larger than in the sample at deposited state which is only 0.27 μΩ cm. The enhancement of AHE is mainly attributed to the interface scattering through post-annealing treatment. - Highlights: • The perpendicular magnetic anisotropy and anomalous Hall effect of Co/Ni multilayer films were studied. • The PMA thermal stability of the Co/Ni ML can be enhanced by HfO{sub 2} capping layer and Pt insertion. • The anomalous Hall resistivity of Co/Ni ML covered by HfO{sub 2} was enhanced by post-annealing treatment.
Proctor, Ashley R.; Ramirez, Gabriel A.; Han, Songfeng; Liu, Ziping; Bubel, Tracy M.; Choe, Regine
2018-03-01
Nicotinamide has been shown to affect blood flow in both tumor and normal tissues, including skeletal muscle. Intraperitoneal injection of nicotinamide was used as a simple intervention to test the sensitivity of noninvasive diffuse correlation spectroscopy (DCS) to changes in blood flow in the murine left quadriceps femoris skeletal muscle. DCS was then compared with the gold-standard fluorescent microsphere (FM) technique for validation. The nicotinamide dose-response experiment showed that relative blood flow measured by DCS increased following treatment with 500- and 1000-mg / kg nicotinamide. The DCS and FM technique comparison showed that blood flow index measured by DCS was correlated with FM counts quantified by image analysis. The results of this study show that DCS is sensitive to nicotinamide-induced blood flow elevation in the murine left quadriceps femoris. Additionally, the results of the comparison were consistent with similar studies in higher-order animal models, suggesting that mouse models can be effectively employed to investigate the utility of DCS for various blood flow measurement applications.
Water diffusion in phosphate-containing hydrogels
International Nuclear Information System (INIS)
George, K.A.; Wentrup-Byrne, E.; Hill, D.J.T.; Whittaker, A.K.
2003-01-01
An understanding of the kinetics and diffusion of liquids through polymeric hydrogels is critical for the successful design and application of these materials in biomedical field, particularly as controlled drug delivery systems. In this study, the mechanisms of water transport and parameters that describe the diffusion process in crosslinked poly(2-hydroxyethylmethacrylate-co-methyloxyethylene phosphate), poly(HEMA-co-MOEP) polymers were investigated. The copolymerisation of HEMA with MOEP was initiated by γ radiolysis with full conversion of monomer to polymer. The sorption of water into the polymers with 0 - 30 mol% MOEP was monitored gravimetrically over a period of 2 - 3 weeks. This study provided an insight into the diffusion mechanism and showed that the PHEMA hydrogel displayed concentration-independent Fickian diffusion. As the concentration of MOEP in the network increased, the diffusion rate and the rigidity of the network also increased in a linear fashion. NMR imaging was used in conjunction with the gravimetric study to elucidate the transport mechanisms, diffusion coefficients and proportionality constants governing the water diffusion in the phosphate-containing polymers. The hydrogels with 3 - 20 mol% MOEP exhibited exponential concentration-dependent Fickian diffusion and the transport mechanism in the system with 30 mol% MOEP was shown to be anomalous. The systems with greater concentrations of MOEP displayed a high degree of fracturing during water sorption and resulted in the ultimate destruction of the cylindrical geometry
Giant anisotropic magnetoresistance in a quantum anomalous Hall insulator
Kandala, Abhinav; Richardella, Anthony; Kempinger, Susan; Liu, Chao-Xing; Samarth, Nitin
2015-01-01
When a three-dimensional ferromagnetic topological insulator thin film is magnetized out-of-plane, conduction ideally occurs through dissipationless, one-dimensional (1D) chiral states that are characterized by a quantized, zero-field Hall conductance. The recent realization of this phenomenon, the quantum anomalous Hall effect, provides a conceptually new platform for studies of 1D transport, distinct from the traditionally studied quantum Hall effects that arise from Landau level formation. An important question arises in this context: how do these 1D edge states evolve as the magnetization is changed from out-of-plane to in-plane? We examine this question by studying the field-tilt-driven crossover from predominantly edge-state transport to diffusive transport in Crx(Bi,Sb)2−xTe3 thin films. This crossover manifests itself in a giant, electrically tunable anisotropic magnetoresistance that we explain by employing a Landauer–Büttiker formalism. Our methodology provides a powerful means of quantifying dissipative effects in temperature and chemical potential regimes far from perfect quantization. PMID:26151318
Anomalous Shape Changes of Silicon Nanopillars by Electrochemical Lithiation
Lee, Seok Woo
2011-07-13
Silicon is one of the most attractive anode materials for use in Li-ion batteries due to its ∼10 times higher specific capacity than existing graphite anodes. However, up to 400% volume expansion during reaction with Li causes particle pulverization and fracture, which results in rapid capacity fading. Although Si nanomaterials have shown improvements in electrochemical performance, there is limited understanding of how volume expansion takes place. Here, we study the shape and volume changes of crystalline Si nanopillars with different orientations upon first lithiation and discover anomalous behavior. Upon lithiation, the initially circular cross sections of nanopillars with 〈100〉, 〈110〉, and 〈111〉 axial orientations expand into cross, ellipse, and hexagonal shapes, respectively. We explain this by identifying a high-speed lithium ion diffusion channel along the 〈110〉 direction, which causes preferential volume expansion along this direction. Surprisingly, the 〈111〉 and 〈100〉 nanopillars shrink in height after partial lithiation, while 〈110〉 nanopillars increase in height. The length contraction is suggested to be due to a collapse of the {111} planes early in the lithiation process. These results give new insight into the Si volume change process and could help in designing better battery anodes. © 2011 American Chemical Society.
Realization of quantum anomalous Hall effect from a magnetic Weyl semimetal
Muechler, Lukas; Liu, Enke; Xu, Qiunan; Felser, Claudia; Sun, Yan
2017-01-01
The quantum anomalous Hall effect (QAHE) and magnetic Weyl semimetals (WSMs) are topological states induced by intrinsic magnetic moments and spin-orbital coupling. Their similarity suggests the possibility of achieving the QAHE by dimensional confinement of a magnetic WSM along one direction. In this study, we investigate the emergence of the QAHE in the two dimensional (2D) limit of magnetic WSMs due to finite size effects. We demonstrate the feasibility of this approach with effective mode...
Contemporary Use of Anomalous Diffraction in Biomolecular Structure Analysis
Energy Technology Data Exchange (ETDEWEB)
Liu Q.; Hendrickson, W.
2017-01-01
The normal elastic X-ray scattering that depends only on electron density can be modulated by an ?anomalous? component due to resonance between X-rays and electronic orbitals. Anomalous scattering thereby precisely identifies atomic species, since orbitals distinguish atomic elements, which enables the multi- and single-wavelength anomalous diffraction (MAD and SAD) methods. SAD now predominates in de novo structure determination of biological macromolecules, and we focus here on the prevailing SAD method. We describe the anomalous phasing theory and the periodic table of phasing elements that are available for SAD experiments, differentiating between those readily accessible for at-resonance experiments and those that can be effective away from an edge. We describe procedures for present-day SAD phasing experiments and we discuss optimization of anomalous signals for challenging applications. We also describe methods for using anomalous signals as molecular markers for tracing and element identification. Emerging developments and perspectives are discussed in brief.
Non-Brownian diffusion in lipid membranes: Experiments and simulations.
Metzler, R; Jeon, J-H; Cherstvy, A G
2016-10-01
The dynamics of constituents and the surface response of cellular membranes-also in connection to the binding of various particles and macromolecules to the membrane-are still a matter of controversy in the membrane biophysics community, particularly with respect to crowded membranes of living biological cells. We here put into perspective recent single particle tracking experiments in the plasma membranes of living cells and supercomputing studies of lipid bilayer model membranes with and without protein crowding. Special emphasis is put on the observation of anomalous, non-Brownian diffusion of both lipid molecules and proteins embedded in the lipid bilayer. While single component, pure lipid bilayers in simulations exhibit only transient anomalous diffusion of lipid molecules on nanosecond time scales, the persistence of anomalous diffusion becomes significantly longer ranged on the addition of disorder-through the addition of cholesterol or proteins-and on passing of the membrane lipids to the gel phase. Concurrently, experiments demonstrate the anomalous diffusion of membrane embedded proteins up to macroscopic time scales in the minute time range. Particular emphasis will be put on the physical character of the anomalous diffusion, in particular, the occurrence of ageing observed in the experiments-the effective diffusivity of the measured particles is a decreasing function of time. Moreover, we present results for the time dependent local scaling exponent of the mean squared displacement of the monitored particles. Recent results finding deviations from the commonly assumed Gaussian diffusion patterns in protein crowded membranes are reported. The properties of the displacement autocorrelation function of the lipid molecules are discussed in the light of their appropriate physical anomalous diffusion models, both for non-crowded and crowded membranes. In the last part of this review we address the upcoming field of membrane distortion by elongated membrane
International Nuclear Information System (INIS)
Stel'makh, V.F.; Suprun-Belevich, Yu.R.; Chelyadinskij, A.R.
1987-01-01
For determination of radiation defects effect on diffusion of the implanted boron in silicon at the pulse annealing, silicon crystals, implanted with boron, preliminary irradiated by silicon ions of different flows for checked defects implantation, were investigated. Silicon crystals additionally implanted by Ge + ions were investigated to research the effect of the incompatibility elastic stresses, emerging in implanted structures due to lattice periods noncoincidence in matrix and alloyed layers, on implanted boron diffusion. It is shown, that abnormally high values of boron diffusion coefficients in silicon at the pulse annealing are explained by silicon interstitial atom participation in redistribution of diffusing boron atoms by two diffusion channels - interstitial and vacation - and by incompatibility elastic stresses effect on diffusion
Rationality of the anomalous dimensions in N=4 SYM theory
International Nuclear Information System (INIS)
Genovese, Luigi; Stanev, Yassen S.
2005-01-01
We reconsider the general constraints on the perturbative anomalous dimensions in conformal invariant QFT and in particular in N=4 SYM with gauge group SU(N). We show that all the perturbative corrections to the anomalous dimension of a renormalized gauge invariant local operator can be written as polynomials in its one loop anomalous dimension. In the N=4 SYM theory the coefficients of these polynomials are rational functions of the number of colours N
Presentation: 3D magnetic inversion by planting anomalous densities
Uieda, Leonardo; Barbosa, Valeria C. F.
2013-01-01
Slides for the presentation "3D magnetic inversion by planting anomalous densities" given at the 2013 AGU Meeting of the Americas in Cancun, Mexico. Note: There was an error in the title of the talk. The correct title should be "3D magnetic inversion by planting anomalous magnetization" Abstract: We present a new 3D magnetic inversion algorithm based on the computationally efficient method of planting anomalous densities. The algorithm consists of an iterative growth of the an...