Energy Technology Data Exchange (ETDEWEB)
Aydin, A; Stiffell, P B, E-mail: a.aydin@sussex.ac.uk [Centre for Physical Electronics and Quantum Technology, School of Engineering and Design, University of Sussex, Brighton, BN1 9QT (United Kingdom)
2011-06-23
We present results of finite element analysis for simple test structures which demonstrate clearly that the measurement situation is complex. The test structure consists of an open geometry parallel plate capacitor within a screened enclosure. Indeed, the presence of earthed objects, even at considerable distances, is shown to have a significant effect on the field geometry close to the source. These simulations are compared with field measurements made using an ultra-high input impedance sensor, the Electric Potential Sensor. A single experimentally determined calibration factor is all that is required to achieve excellent agreement between experimental measurements and the results of the simulations. Given this, the sensor is capable of mapping accurately, and in a non-perturbative manner, the spatial potential both within and outside of the test structure.
Non perturbative methods in two dimensional quantum field theory
Abdalla, Elcio; Rothe, Klaus D
1991-01-01
This book is a survey of methods used in the study of two-dimensional models in quantum field theory as well as applications of these theories in physics. It covers the subject since the first model, studied in the fifties, up to modern developments in string theories, and includes exact solutions, non-perturbative methods of study, and nonlinear sigma models.
Alien calculus and non perturbative effects in Quantum Field Theory
Bellon, Marc P.
2016-12-01
In many domains of physics, methods for dealing with non-perturbative aspects are required. Here, I want to argue that a good approach for this is to work on the Borel transforms of the quantities of interest, the singularities of which give non-perturbative contributions. These singularities in many cases can be largely determined by using the alien calculus developed by Jean Écalle. My main example will be the two point function of a massless theory given as a solution of a renormalization group equation.
Kovtun, Pavel; Ünsal, Mithat; Yaffe, Laurence G.
2003-12-01
We prove an equivalence, in the large N limit, between certain U(N) gauge theories containing adjoint representation matter fields and their orbifold projections. Lattice regularization is used to provide a non-perturbative definition of these theories; our proof applies in the strong coupling, large mass phase of the theories. Equivalence is demonstrated by constructing and comparing the loop equations for a parent theory and its orbifold projections. Loop equations for both expectation values of single-trace observables, and for connected correlators of such observables, are considered; hence the demonstrated non-perturbative equivalence applies to the large N limits of both string tensions and particle spectra.
Non-perturbative heterogeneous mean-field approach to epidemic spreading in complex networks
Gomez, Sergio; Moreno, Yamir; Arenas, Alex
2011-01-01
Since roughly a decade ago, network science has focused among others on the problem of how the spreading of diseases depends on structural patterns. Here, we contribute to further advance our understanding of epidemic spreading processes by proposing a non-perturbative formulation of the heterogeneous mean field approach that has been commonly used in the physics literature to deal with this kind of spreading phenomena. The non-perturbative equations we propose have no assumption about the proximity of the system to the epidemic threshold, nor any linear approximation of the dynamics. In particular, we first develop a probabilistic description at the node level of the epidemic propagation for the so-called susceptible-infected-susceptible family of models, and after we derive the corresponding heterogeneous mean-field approach. We propose to use the full extension of the approach instead of pruning the expansion to first order, which leads to a non-perturbative formulation that can be solved by fixed point it...
From charge motion in general magnetic fields to the non perturbative gyrokinetic equation
Energy Technology Data Exchange (ETDEWEB)
Di Troia, C., E-mail: claudio.ditroia@enea.it [ENEA Unità tecnica Fusione, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Rome (Italy)
2015-04-15
The exact analytical description of non relativistic charge motion in general magnetic fields is, apparently, a simple problem, even if it has not been solved until now, apart for rare cases. The key feature of the present derivation is to adopt a non perturbative magnetic field description to find new solutions of motion. Among all solutions, two are particularly important: guiding particle and gyro-particle solutions. The guiding particle has been characterized to be minimally coupled to the magnetic field; the gyro-particle has been defined to be maximally coupled to the magnetic field and, also, to move on a closed orbit. The generic charged particle motion is shown to be expressed as the sum of such particular solutions. This non perturbative approach corresponds to the description of the particle motion in the gyro-center and/or guiding center reference frame obtained at all the orders of the modern gyro-center transformation. The Boltzmann equation is analyzed with the described exact guiding center coordinates. The obtained gyrokinetic equation is solved for the Boltzmann equation at marginal stability conditions.
Non-Perturbative Self-Consistent Model in SU(N Gauge Field Theory
Directory of Open Access Journals (Sweden)
Koshelkin A.V.
2012-06-01
Full Text Available Non-perturbative quasi-classical model in a gauge theory with the Yang-Mills (YM field is developed. The self-consistent solutions of the Dirac equation in the SU(N gauge field, which is in the eikonal approximation, and the Yang-Mills (YM equations containing the external fermion current are solved. It shown that the developed model has the self-consistent solutions of the Dirac and Yang-Mills equations at N ≥ 3. In this way, the solutions take place provided that the fermion and gauge fields exist simultaneously, so that the fermion current completely compensates the current generated by the gauge field due to self-interaction of it.
3rd UK-QFT Meeting: Non-Perturbative Quantum Field Theory and Quantum Gravity
2014-01-01
The meeting aims to bringing together Students, Postdoctoral Researchers and Senior Scientists to discuss recent trends in advanced Quantum Field Theory and Quantum Gravity. The format of the meeting is a series of informal talks to allow for discussion and the exchange of ideas amongst participants. We plan for up to 8 slots for short presentations depending on demand and one final longer seminar given by Frank Saueressig (Mainz). This is the third meeting of its kind and details on the previous two can be found on the following: 1st UK-QFT Meeting: Non-perturbative aspects in field theory (KCL) 2nd UK-QFT Meeting: Advances in quantum field theory and gravity (Sussex)
Musso, Daniele
2012-01-01
The non-perturbative dynamics of quantum field theories is studied using theoretical tools inspired by string formalism. Two main lines are developed: the analysis of stringy instantons in a class of four-dimensional N=2 gauge theories and the holographic study of the minimal model for a strongly coupled unbalanced superconductor. The field theory instanton calculus admits a natural and efficient description in terms of D-brane models. In addition, the string viewpoint offers the possibility of generalizing the ordinary instanton configurations. Even though such generalized, or stringy, instantons would be absent in a purely field-theoretical, low-energy treatment, we demonstrate that they do alter the IR effective description of the brane dynamics by introducing contributions related to the string scale. In the first part of this thesis we compute explicitly the stringy instanton corrections to the effective prepotential in a class of quiver gauge theories. In the second part of the thesis, we present a deta...
Anisotropic non-perturbative zero modes for passively advected magnetic fields
Lanotte, A
1999-01-01
A first analytical assessment of the role of anisotropic corrections to the isotropic anomalous scaling exponents is given for the $d$-dimensional kinematic dynamo problem in the presence of a mean magnetic field. The velocity advecting the magnetic field changes very rapidly in time and scales with a positive exponent $\\xi$. Inertial-range anisotropic contributions to the scaling exponents of magnetic correlations are associated to zero modes and have been calculated non-perturbatively. For $d=3$, the limits $\\xi\\mapsto 0$ yelds $\\zeta_n=n+ \\xi [(n+2) (2 n^2-7 n-3)]/[2 (3+2 n) (1+2 n)]$ where $n$ is the order in the Legendre polynomial decomposition. Conjectures on the fact that anisotropic components cannot change the isotropic threshold to the dynamo effect are also made.
Chishtie, F A
2002-01-01
Pade approximants (PA) have been widely applied in practically all areas of physics. This thesis focuses on developing PA as tools for both perturbative and non- perturbative quantum field theory (QFT). In perturbative QFT, we systematically estimate higher (unknown) loop terms via the asymptotic formula devised by Samuel et al. This algorithm, generally denoted as the asymptotic Pade approximation procedure (APAP), has greatly enhanced scope when it is applied to renormalization-group-(RG-) invariant quantities. A presently-unknown higher-loop quantity can then be matched with the approximant over the entire momentum region of phenomenological interest. Furthermore, the predicted value of the RG coefficients can be compared with the RG-accessible coefficients (at the higher-loop order), allowing a clearer indication of the accuracy of the predicted RG-inaccessible term. This methodology is applied to hadronic Higgs decay rates (H → bb¯ and H → gg, both within the Standard Model and...
Tellgren, Erik I; Fliegl, Heike
2013-10-28
In the present study a non-perturbative approach to ab initio calculations of molecules in strong, linearly varying, magnetic fields is developed. The use of London atomic orbitals (LAOs) for non-uniform magnetic fields is discussed and the standard rationale of gauge-origin invariance is generalized to invariance under arbitrary constant shifts of the magnetic vector potential. Our approach is applied to study magnetically induced anapole moments (or toroidal moments) and the related anapole susceptibilities for a test set of chiral and nonchiral molecules. For the first time numerical anapole moments are accessible on an ab initio level of theory. Our results show that the use of London atomic orbitals dramatically improves the basis set convergence also for magnetic properties related to non-uniform magnetic fields, at the cost that the Hellmann-Feynman theorem does not apply for a finite LAO basis set. It is shown that the mixed anapole susceptibility can be related to chirality, since its trace vanishes for an achiral molecule.
Quantum fields in the non-perturbative regime. Yang-Mills theory and gravity
Energy Technology Data Exchange (ETDEWEB)
Eichhorn, Astrid
2011-09-06
In this thesis we study candidates for fundamental quantum field theories, namely non-Abelian gauge theories and asymptotically safe quantum gravity. Whereas the first ones have a stronglyinteracting low-energy limit, the second one enters a non-perturbative regime at high energies. Thus, we apply a tool suited to the study of quantum field theories beyond the perturbative regime, namely the Functional Renormalisation Group. In a first part, we concentrate on the physical properties of non-Abelian gauge theories at low energies. Focussing on the vacuum properties of the theory, we present an evaluation of the full effective potential for the field strength invariant F{sub {mu}}{sub {nu}}F{sup {mu}}{sup {nu}} from non-perturbative gauge correlation functions and find a non-trivial minimum corresponding to the existence of a dimension four gluon condensate in the vacuum. We also relate the infrared asymptotic form of the {beta} function of the running background-gauge coupling to the asymptotic behavior of Landau-gauge gluon and ghost propagators and derive an upper bound on their scaling exponents. We then consider the theory at finite temperature and study the nature of the confinement phase transition in d = 3+1 dimensions in various non-Abelian gauge theories. For SU(N) with N= 3,..,12 and Sp(2) we find a first-order phase transition in agreement with general expectations. Moreover our study suggests that the phase transition in E(7) Yang-Mills theory also is of first order. Our studies shed light on the question which property of a gauge group determines the order of the phase transition. In a second part we consider asymptotically safe quantum gravity. Here, we focus on the Faddeev-Popov ghost sector of the theory, to study its properties in the context of an interacting UV regime. We investigate several truncations, which all lend support to the conjecture that gravity may be asymptotically safe. In a first truncation, we study the ghost anomalous dimension
Kar, Supriya
2016-01-01
We show that the massless form fields, in $(4+1)$-dimensional non-perturbation theory of emergent gravity, become massive in a perturbative phase without Higgs mechanism. In particular an axionic scalar sourced by a non-perturbative dynamical correction is absorbed by the form fields to describe a massive NS field theory on an emergent gravitational pair of $(3{\\bar 3})$-brane. Arguably the novel idea of Higgs mechanism is naturally invoked in an emergent gravity underlying a ${\\rm CFT}_6$. Analysis reveals "gravito-weak" and "electro-weak" phases respectively on a vacuum pair in $(4+1)$ and $(3+1)$-dimensions. It is argued that the massive NS field quanta may govern an emergent graviton on a gravitational $3$-brane.
Non-Perturbative Renormalization
Mastropietro, Vieri
2008-01-01
The notion of renormalization is at the core of several spectacular achievements of contemporary physics, and in the last years powerful techniques have been developed allowing to put renormalization on a firm mathematical basis. This book provides a self-consistent and accessible introduction to the sophisticated tools used in the modern theory of non-perturbative renormalization, allowing an unified and rigorous treatment of Quantum Field Theory, Statistical Physics and Condensed Matter models. In particular the first part of this book is devoted to Constructive Quantum Field Theory, providi
Instantons and large N an introduction to non-perturbative methods in quantum field theory
Marino, Marcos
2015-01-01
This highly pedagogical textbook for graduate students in particle, theoretical and mathematical physics, explores advanced topics of quantum field theory. Clearly divided into two parts; the first focuses on instantons with a detailed exposition of instantons in quantum mechanics, supersymmetric quantum mechanics, the large order behavior of perturbation theory, and Yang-Mills theories, before moving on to examine the large N expansion in quantum field theory. The organised presentation style, in addition to detailed mathematical derivations, worked examples and applications throughout, enables students to gain practical experience with the tools necessary to start research. The author includes recent developments on the large order behaviour of perturbation theory and on large N instantons, and updates existing treatments of classic topics, to ensure that this is a practical and contemporary guide for students developing their understanding of the intricacies of quantum field theory.
Kalinichenko, Igor; Kazinski, Peter
2014-08-01
The explicit expressions for the one-loop non-perturbative corrections to the gravitational effective action induced by a scalar field on a stationary gravitational background are obtained both at zero and finite temperatures. The perturbative and non-perturbative contributions to the one-loop effective action are explicitly separated. It is proved that, after a suitable renormalization, the perturbative part of the effective action at zero temperature can be expressed in a covariant form solely in terms of the metric and its derivatives. This part coincides with the known large mass expansion of the one-loop effective action. The non-perturbative part of the renormalized one-loop effective action at zero temperature is proved to depend explicitly on the Killing vector defining the vacuum state of quantum fields. This part cannot be expressed in a covariant way through the metric and its derivatives alone. The implications of this result for the structure and symmetries of the effective action for gravity are discussed.
Kalinichenko, I S
2014-01-01
The explicit expressions for the one-loop non-perturbative corrections to the gravitational effective action induced by a scalar field on a stationary gravitational background are obtained both at zero and finite temperatures. The perturbative and non-perturbative contributions to the one-loop effective action are explicitly separated. It is proved that, after a suitable renormalization, the perturbative part of the effective action at zero temperature can be expressed in a covariant form solely in terms of the metric and its derivatives. This part coincides with the known large mass expansion of the one-loop effective action. The non-perturbative part of the renormalized one-loop effective action at zero temperature is proved to depend explicitly on the Killing vector defining the vacuum state of quantum fields. This part cannot be expressed in a covariant way through the metric and its derivatives alone. The implications of this result for the structure and symmetries of the effective action for gravity are...
Electric fields and quantum wormholes
Engelhardt, Dalit; Iqbal, Nabil
2015-01-01
Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "quantum wormhole". We demonstrate within low-energy effective field theory that there is a precise sense in which electric fields can also thread such quantum wormholes. We define a non-perturbative "wormhole susceptibility" that measures the ease of passing an electric field through any sort of wormhole. The susceptibility of a quantum wormhole is suppressed by powers of the U(1) gauge coupling relative to that for a classical wormhole but can be made numerically equal with a sufficiently large amount of entangled matter.
Makhoute, A.; Agueny, H.; Dubois, A.; Ajana, I.; Taoutioui, A.
2016-04-01
We report a detailed analysis of electron-helium scattering in the presence of a laser field; focusing on the elastic process of helium atoms from the ground state 11 S. The process under investigation is dealt with a nonperturbative approach using the Volkov wave function to describe the incident and scattered electrons, while the laser-target interaction is treated by using the Floquet method. The interaction of the incident electron with the atomic target is treated within the first Born approximation. Our results are perfectly consistent with the experimental data of DeHarak et al and with the Kroll-Watson approximation results for both one and two photon emission. We have investigated the effect of nonresonant and near resonant laser field on the electron-helium elastic collision process. It was found that the differential cross section is sensitive to the intensity and the frequency of the laser field. In the case of a non resonant laser field, dressing effects are important at small scattering angles. For a near-resonant laser photon energy, those effects are strongly reduced in the forward direction.
Balram, Ajit C.; Dhar, Deepak
2012-03-01
We consider the spherical model on a spider-web graph. This graph is effectively infinite dimensional, similar to the Bethe lattice, but has loops. We show that these lead to non-trivial corrections to the simple mean-field behavior. We first determine all normal modes of the coupled springs problem on this graph, using its large symmetry group. In the thermodynamic limit, the spectrum is a set of δ-functions, and all the modes are localized. The fractional number of modes with frequency less than ω varies as exp ( - C/ω) for ω tending to zero, where C is a constant. For an unbiased random walk on the vertices of this graph, this implies that the probability of return to the origin at time t varies as exp ( - C‧t1/3), for large t, where C‧ is a constant. For the spherical model, we show that while the critical exponents take the values expected from the mean-field theory, the free energy per site at temperature T, near and above the critical temperature Tc, also has an essential singularity of the type exp [ - K(T - Tc)-1/2].
New Methods in Non-Perturbative QCD
Energy Technology Data Exchange (ETDEWEB)
Unsal, Mithat [North Carolina State Univ., Raleigh, NC (United States)
2017-01-31
In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), and there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactifications which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.
Non-perturbative Euler-Heisenberg Lagrangian and paraelectricity in magnetized massless QED
Energy Technology Data Exchange (ETDEWEB)
Ferrer, Efrain J. [Department of Physics, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968 (United States); Incera, Vivian de la, E-mail: vincera@utep.edu [Department of Physics, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968 (United States); Sanchez, Angel [Department of Physics, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968 (United States)
2012-11-21
In this paper we calculate the non-perturbative Euler-Heisenberg Lagrangian for massless QED in a strong magnetic field H, where the breaking of the chiral symmetry is dynamically catalyzed by the external magnetic field via the formation of an electro-positron condensate. This chiral condensate leads to the generation of dynamical parameters that have to be found as solutions of non-perturbative Schwinger-Dyson equations. Since the electron-positron pairing mechanism leading to the breaking of the chiral symmetry is mainly dominated by the contributions from the infrared region of momenta much smaller than {radical}(eH), the magnetic field introduces a dynamical ultraviolet cutoff in the theory that also enters in the non-perturbative Euler-Heisenberg action. Using this action, we show that the system exhibits a significant paraelectricity in the direction parallel to the magnetic field. The non-perturbative nature of this effect is reflected in the non-analytic dependence of the obtained electric susceptibility on the fine-structure constant. The strong paraelectricity in the field direction is linked to the orientation of the electric dipole moments of the pairs that form the chiral condensate. The large electric susceptibility can be used to detect the realization of the magnetic catalysis of chiral symmetry breaking in physical systems.
Effects of a static electric field on two-color photoassociation of heteronuclear atom-pairs
Chakraborty, Debashree
2013-01-01
We study non-perturbative effects of a static electric field on two-color photoassociation of heteronuclear atom-pairs. A static electric field induces anisotropy in scattering between two heteronuclear atoms and hybridizes field-free rotational states of heteronuclear dimers or polar molecules. In a previous paper [D. Chakraborty $\\it {et.}$ $\\it {al.}$, J. Phys. B 44, 095201 (2011)], the effects of a static electric field on one-color photoassociation between heteronuclear atoms has been described through field-modified ground-state scattering states, neglecting electric field effects on heteronuclear diatomic bound states. To study the effects of a static electric field on heteronuclear bound states, and the resulting influence on Raman-type two-color photoassociation between heteronuclear atoms in the presence of a static electric field, we develop a non-perturbative numerical method to calculate static electric field-dressed heteronuclear bound states. We show that the static electric field induced scatt...
Perturbative renormalization of the electric field correlator
Christensen, C
2016-01-01
The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ~12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Perturbative renormalization of the electric field correlator
Directory of Open Access Journals (Sweden)
C. Christensen
2016-04-01
Full Text Available The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3 gauge theory, finding a ∼12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Perturbative renormalization of the electric field correlator
Christensen, C.; Laine, M.
2016-04-01
The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ∼ 12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.
Electric fields and electrical insulation
DEFF Research Database (Denmark)
McAllister, Iain Wilson
2002-01-01
The adoption of a field-theoretical approach to problems arising in the framework of electrical insulation is discussed with reference to six main topics, which have been addressed over the last 30 years. These include uniform field electrodes, Green's differential equation, electrode surface......, it is amply demonstrated that such an approach can lead to significant progress in many areas of electrical insulation....
Non-perturbative description of quantum systems
Feranchuk, Ilya; Le, Van-Hoang; Ulyanenkov, Alexander
2015-01-01
This book introduces systematically the operator method for the solution of the Schrödinger equation. This method permits to describe the states of quantum systems in the entire range of parameters of Hamiltonian with a predefined accuracy. The operator method is unique compared with other non-perturbative methods due to its ability to deliver in zeroth approximation the uniformly suitable estimate for both ground and excited states of quantum system. The method has been generalized for the application to quantum statistics and quantum field theory. In this book, the numerous applications of operator method for various physical systems are demonstrated. Simple models are used to illustrate the basic principles of the method which are further used for the solution of complex problems of quantum theory for many-particle systems. The results obtained are supplemented by numerical calculations, presented as tables and figures.
Electric Field Imaging Project
Wilcutt, Terrence; Hughitt, Brian; Burke, Eric; Generazio, Edward
2016-01-01
NDE historically has focused technology development in propagating wave phenomena with little attention to the field of electrostatics and emanating electric fields. This work is intended to bring electrostatic imaging to the forefront of new inspection technologies, and new technologies in general. The specific goals are to specify the electric potential and electric field including the electric field spatial components emanating from, to, and throughout volumes containing objects or in free space.
Non-perturbative Nekrasov partition function from string theory
Energy Technology Data Exchange (ETDEWEB)
Antoniadis, I., E-mail: ignatios.antoniadis@cern.ch [Department of Physics, CERN – Theory Division, CH-1211 Geneva 23 (Switzerland); Florakis, I., E-mail: florakis@mppmu.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Hohenegger, S., E-mail: stefan.hohenegger@cern.ch [Department of Physics, CERN – Theory Division, CH-1211 Geneva 23 (Switzerland); Narain, K.S., E-mail: narain@ictp.trieste.it [High Energy Section, The Abdus Salam International Center for Theoretical Physics, Strada Costiera, 11-34014 Trieste (Italy); Zein Assi, A., E-mail: zeinassi@cern.ch [Department of Physics, CERN – Theory Division, CH-1211 Geneva 23 (Switzerland); Centre de Physique Théorique (UMR CNRS 7644), Ecole Polytechnique, 91128 Palaiseau (France)
2014-03-15
We calculate gauge instanton corrections to a class of higher derivative string effective couplings introduced in [1]. We work in Type I string theory compactified on K3×T{sup 2} and realise gauge instantons in terms of D5-branes wrapping the internal space. In the field theory limit we reproduce the deformed ADHM action on a general Ω-background from which one can compute the non-perturbative gauge theory partition function using localisation. This is a non-perturbative extension of [1] and provides further evidence for our proposal of a string theory realisation of the Ω-background.
Non-perturbative Euler-Heisenberg Lagrangian and Paraelectricity in Magnetized Massless QED
Ferrer, Efrain J; Sanchez, Angel
2012-01-01
Using the non-perturbative Euler-Heisenberg Lagrangian for massless QED in a strong magnetic field, we show that the chiral-symmetry-broken phase of massless QED in the presence of a magnetic field exhibits significant paraelectricity. A large anisotropic electric susceptibility develops in the strong-field region, where most of the fermions are confined to their lowest Landau level, and dynamical mass and anomalous magnetic moment are generated via the magnetic catalysis mechanism. The nonperturbative nature of this effect is reflected in the non-analytic dependence of the electric susceptibility on the fine-structure constant. The strong paraelectricity is linked to the electric dipole moments of the particle/anti-particle pairs that form the chiral condensate. The large electric susceptibility can be used to detect the realization of the magnetic catalysis of chiral symmetry breaking in physical systems.
Chakravorti, Sivaji
2015-01-01
This book prepares newcomers to dive into the realm of electric field analysis. The book details why one should perform electric field analysis and what are its practical implications. It emphasizes both the fundamentals and modern computational methods of electric machines. The book covers practical applications of the numerical methods in high voltage equipment, including transmission lines, power transformers, cables, and gas insulated systems.
Non-perturbative quantum geometry III
Krefl, Daniel
2016-08-01
The Nekrasov-Shatashvili limit of the refined topological string on toric Calabi-Yau manifolds and the resulting quantum geometry is studied from a non-perturbative perspective. The quantum differential and thus the quantum periods exhibit Stokes phenomena over the combined string coupling and quantized Kähler moduli space. We outline that the underlying formalism of exact quantization is generally applicable to points in moduli space featuring massless hypermultiplets, leading to non-perturbative band splitting. Our prime example is local ℙ1 + ℙ1 near a conifold point in moduli space. In particular, we will present numerical evidence that in a Stokes chamber of interest the string based quantum geometry reproduces the non-perturbative corrections for the Nekrasov-Shatashvili limit of 4d supersymmetric SU(2) gauge theory at strong coupling found in the previous part of this series. A preliminary discussion of local ℙ2 near the conifold point in moduli space is also provided.
Non-Perturbative Quantum Geometry III
Krefl, Daniel
2016-01-01
The Nekrasov-Shatashvili limit of the refined topological string on toric Calabi-Yau manifolds and the resulting quantum geometry is studied from a non-perturbative perspective. The quantum differential and thus the quantum periods exhibit Stockes phenomena over the combined string coupling and quantized Kaehler moduli space. We outline that the underlying formalism of exact quantization is generally applicable to points in moduli space featuring massless hypermultiplets, leading to non-perturbative band splitting. Our prime example is local P1xP1 near a conifold point in moduli space. In particular, we will present numerical evidence that in a Stockes chamber of interest the string based quantum geometry reproduces the non-perturbative corrections for the Nekrasov-Shatashvili limit of 4d supersymmetric SU(2) gauge theory at strong coupling found in the previous part of this series. A preliminary discussion of local P2 near the conifold point in moduli space is also provided.
The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...
Non-perturbative QCD and hadron physics
Cobos-Martínez, J. J.
2016-10-01
A brief exposition of contemporary non-perturbative methods based on the Schwinger-Dyson (SDE) and Bethe-Salpeter equations (BSE) of Quantum Chromodynamics (QCD) and their application to hadron physics is given. These equations provide a non-perturbative continuum formulation of QCD and are a powerful and promising tool for the study of hadron physics. Results on some properties of hadrons based on this approach, with particular attention to the pion distribution amplitude, elastic, and transition electromagnetic form factors, and their comparison to experimental data are presented.
Dielectrics in electric fields
Raju, Gorur G
2003-01-01
Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.
Non-perturbative Heavy Quark Effective Theory
DEFF Research Database (Denmark)
Della Morte, Michele; Heitger, Jochen; Simma, Hubert;
2015-01-01
We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays...
Non-perturbative Heavy Quark Effective Theory
DEFF Research Database (Denmark)
Della Morte, Michele; Heitger, Jochen; Simma, Hubert
2015-01-01
We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays...
Non-Perturbative Flat Direction Decay
Basboll, A; Riva, F; West, S M; Basboll, Anders; Maybury, David; Riva, Francesco; West, Stephen M.
2007-01-01
We argue that supersymmetric flat direction vevs can decay non-perturbatively via preheating. Considering the case of a single flat direction, we explicitly calculate the scalar potential in the unitary gauge for a U(1) theory and show that the mass matrix for excitations around the flat direction has non-diagonal entries which vary with the phase of the flat direction vev. Furthermore, this mass matrix has 2 zero eigenvalues (associated with the excitations along the flat direction) whose eigenstates change with time. We show that these 2 light degrees of freedom are produced copiously in the non-perturbative decay of the flat direction vev. We also comment on the application of these results to the MSSM flat direction H_uL.
Non-perturbative renormalization in kaon decays
Donini, Andrea; Martinelli, G; Rossi, G C; Talevi, M; Testa, M; Vladikas, A
1996-01-01
We discuss the application of the MPSTV non-perturbative method \\cite{NPM} to the operators relevant to kaon decays. This enables us to reappraise the long-standing question of the $\\Delta I=1/2$ rule, which involves power-divergent subtractions that cannot be evaluated in perturbation theory. We also study the mixing with dimension-six operators and discuss its implications to the chiral behaviour of the $B_K$ parameter.
Non-perturbative quark mass renormalization
Capitani, S.; Luescher, M.; Sint, S.; Sommer, R.; Weisz, P.; Wittig, H.
1998-01-01
We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\\Lambda$--parameter in this theory with completely controlled errors.
Non-Perturbative Theory of Dispersion Interactions
Boström, M; Persson, C; Parsons, D F; Buhmann, S Y; Brevik, I; Sernelius, Bo E
2015-01-01
Some open questions exist with fluctuation-induced forces between extended dipoles. Conventional intuition derives from large-separation perturbative approximations to dispersion force theory. Here we present a full non-perturbative theory. In addition we discuss how one can take into account finite dipole size corrections. It is of fundamental value to investigate the limits of validity of the perturbative dispersion force theory.
Dzhunushaliev, Vladimir
2016-01-01
The contribution of gluon fields to the proton spin is calculated. The calculations are performed following non-perturbative Heisenberg's quantization technique. In our approach a proton is considered as consisting of three quarks connected by three flux tubes. The flux tubes contain colour longitudinal electric and transversal electric and magnetic fields. The longitudinal electric field causes the interaction forces between quarks. The quantum superposition of the transversal fields causes the appearance of the angular momentum density. From our calculations, we obtain that the contribution of the gluon field from the flux tubes to the proton spin is of the order of $15\\%$. The dimensionless relation between the angular momentum and the mass of the gluon fields is obtained. The experimental verification of this relation is discussed. Simple numerical relation between the proton mass, the speed of light and the proton radius, which is of the same order as the Planck constant, is discussed.
Non-perturbative study of QCD correlators
Lokhov, A Y
2006-01-01
This PhD dissertation is devoted to a non-perturbative study of QCD correlators. The main tool that we use is lattice QCD. We concentrated our efforts on the study of the main correlators of the pure Yang - Mills theory in the Landau gauge, namely the ghost and the gluon propagators. We are particularly interested in determining the $\\Lqcd$ parameter. It is extracted by means of perturbative predictions available up to NNNLO. The related topic is the influence of non-perturbative effects that show up as appearance of power-corrections to the low-momentum behaviour of the Green functions. A new method of removing these power corrections allows a better estimate of $\\Lqcd$. Our result is $\\Lambda^{n_f=0}_{\\ms} = 269(5)^{+12}_{-9}$ MeV. Another question that we address is the infrared behaviour of Green functions, at momenta of order and below $\\Lqcd$. At low energy the momentum dependence of the propagators changes considerably, and this is probably related to confinement. The lattice approach allows to check t...
Non-Perturbative Quantum Dynamics of a New Inflation Model
Boyanovsky, D; De Vega, H J; Holman, R; Kumar, S P
1998-01-01
We consider an O(N) model coupled self-consistently to gravity in the semiclassical approximation, where the field is subject to `new inflation' type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. We find that spinodal instabilities drive the growth of non-perturbatively large quantum fluctuations which shut off the inflationary growth of the scale factor. We find that a very specific combination of these large fluctuations plus the inflaton zero mode assemble into a new effective field. This new field behaves classically and it is the object which actually rolls down. We show how this reinterpretation saves the standard picture of how metric perturbations are generated during inflation and that the spinodal growth of fluctuations dominates the time dependence of the Bardeen variable for superhorizon modes during inflation. We compute the amplitude and index for the spectrum of scalar density and tensor perturb...
A non-perturbative approach to relativistic quantum communication channels
Landulfo, Andre G S
2016-01-01
We investigate the transmission of both classical and quantum information between two arbitrary observers in globally hyperbolic spacetimes using a quantum field as a communication channel. The field is supposed to be in some arbitrary quasifree state and no choice of representation of its canonical commutation relations is made. Both sender and receiver posses some localized two-level quantum system with which they can interact with the quantum field to prepare the input and receive the output of the channel, respectively. The interaction between the two-level systems and the quantum field is such that one can trace out the field degrees of freedom exactly and thus obtain the quantum channel in a non-perturbative way. We end the paper determining the unassisted as well as the entanglement-assisted classical and quantum channel capacities.
Non-perturbative match of ultraviolet renormalon
Zakharov, V I
2003-01-01
The paper is motivated by observation of a kind of branes in the vacuum state of the lattice SU(2) gluodynamics. The branes represent two-dimensional vortices whose total area scales in physical units while the non-Abelian action diverges in the ultraviolet. We consider the question whether effects of the branes can be accommodated into the continuum theory. We demonstrate that at least in case of the gluon condensate (plaquette action) and of the heavy quark potential the contribution of the branes corresponds to the ultraviolet renormalon. Thus, the vortices might represent a non-perturbative match of the ultraviolet renormalon. Such an identification constrains, in turn, properties of the branes.
Non-perturbative quantization of the electroweak model's electrodynamic sector
Fry, M P
2015-01-01
Consider the Euclidean functional integral representation of any physical process in the electroweak model. Integrating out the fermion degrees of freedom introduces twenty-four fermion determinants. These multiply the Gaussian functional measures of the Maxwell, $Z$, $W$ and Higgs fields to give an effective functional measure. Suppose the functional integral over the Maxwell field is attempted first. This paper is concerned with the large amplitude behavior of the Maxwell effective measure. It is assumed that the large amplitude variation of this measure is insensitive to the presence of the $Z$, $W$ and $H$ fields; they are assumed to be a subdominant perturbation of the large amplitude Maxwell sector. Accordingly, we need only examine the large amplitude variation of a single QED fermion determinant. To facilitate this the Schwinger proper time representation of this determinant is decomposed into a sum of three terms. The advantage of this is that the separate terms can be non-perturbatively estimated fo...
Introduction to non-perturbative heavy quark effective theory
Energy Technology Data Exchange (ETDEWEB)
Sommer, R. [DESY, Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2010-08-15
My lectures on the effective field theory for heavy quarks, an expansion around the static limit, concentrate on the motivation and formulation of HQET, its renormalization and discretization. This provides the basis for understanding that and how this effective theory can be formulated fully non-perturbatively in the QCD coupling, while by the very nature of an effective field theory, it is perturbative in the expansion parameter 1/m. After the couplings in the effective theory have been determined, the result at a certain order in 1/m is unique up to higher order terms in 1/m. In particular the continuum limit of the lattice regularized theory exists and leaves no trace of how it was regularized. In other words, the theory yields an asymptotic expansion of the QCD observables in 1/m - as usual in a quantum field theory modified by powers of logarithms. None of these properties has been shown rigorously (e.g. to all orders in perturbation theory) but perturbative computations and recently also non-perturbative lattice results give strong support to this ''standard wisdom''. A subtle issue is that a theoretically consistent formulation of the theory is only possible through a non-perturbative matching of its parameters with QCD at finite values of 1/m. As a consequence one finds immediately that the splitting of a result for a certain observable into, for example, lowest order and first order is ambiguous. Depending on how the matching between effective theory and QCD is done, a first order contribution may vanish and appear instead in the lowest order. For example, the often cited phenomenological HQET parameters anti {lambda} and {lambda}{sub 1} lack a unique non-perturbative definition. But this does not affect the precision of the asymptotic expansion in 1/m. The final result for an observable is correct up to order (1/m){sup n+1} if the theory was treated including (1/m){sup n} terms. Clearly, the weakest point of HQET is that it
Electron-Positron Pair Production in Structured Pulses of Electric Fields
Kohlfürst, Christian
2012-01-01
The non-perturbative electron-positron pair production in time-dependent electric fields is investigated. The quantum kinetic formalism is employed in order to calculate the electron density for various field configurations. The corresponding set of first order, ordinary differential equations is analyzed and numerically solved. The focus of this study lies on the dynamically assisted Schwinger effect in pulsed electric fields with at least two different time scales. Furthermore, interference effects arising in setups with multiple pulses are examined and first results for an optimization of the particle number yield by pulse-shaping are given.
Non-Perturbative Topological Strings And Conformal Blocks
Cheng, Miranda C N; Vafa, Cumrun
2010-01-01
We give a non-perturbative completion of a class of closed topological string theories in terms of building blocks of dual open strings. In the specific case where the open string is given by a matrix model these blocks correspond to a choice of integration contour. We then apply this definition to the AGT setup where the dual matrix model has logarithmic potential and is conjecturally equivalent to Liouville conformal field theory. By studying the natural contours of these matrix integrals and their monodromy properties, we propose a precise map between topological string blocks and Liouville conformal blocks. Remarkably, this description makes use of the light-cone diagrams of closed string field theory, where the critical points of the matrix potential correspond to string interaction points.
Non-perturbative topological strings and conformal blocks
Cheng, Miranda C. N.; Dijkgraaf, Robbert; Vafa, Cumrun
2011-09-01
We give a non-perturbative completion of a class of closed topological string theories in terms of building blocks of dual open strings. In the specific case where the open string is given by a matrix model these blocks correspond to a choice of integration contour. We then apply this definition to the AGT setup where the dual matrix model has logarithmic potential and is conjecturally equivalent to Liouville conformal field theory. By studying the natural contours of these matrix integrals and their monodromy properties, we propose a precise map between topological string blocks and Liouville conformal blocks. Remarkably, this description makes use of the light-cone diagrams of closed string field theory, where the critical points of the matrix potential correspond to string interaction points.
World-Line Formalism: Non-Perturbative Applications
Directory of Open Access Journals (Sweden)
Dmitry Antonov
2016-11-01
Full Text Available This review addresses the impact on various physical observables which is produced by confinement of virtual quarks and gluons at the level of the one-loop QCD diagrams. These observables include the quark condensate for various heavy flavors, the Yang-Mills running coupling with an infra-red stable fixed point, and the correlation lengths of the stochastic Yang-Mills fields. Other non-perturbative applications of the world-line formalism presented in the review are devoted to the determination of the electroweak phase-transition critical temperature, to the derivation of a semi-classical analogue of the relation between the chiral and the gluon QCD condensates, and to the calculation of the free energy of the gluon plasma in the high-temperature limit. As a complementary result, we demonstrate Casimir scaling of k-string tensions in the Gaussian ensemble of the stochastic Yang-Mills fields.
What Are Electric and Magnetic Fields? (EMF)
... take for granted. What are electric and magnetic fields? Electric and magnetic fields (EMF) are invisible lines of ... humans. AC electric power produces electric and magnetic fields that create weak electric currents in humans. Being exposed to some kinds ...
Finite pulse effects on $e^{+}e^{-}$ pair creation from strong electric fields
Taya, Hidetoshi; Itakura, Kazunori
2014-01-01
We investigate electron-positron pair creation from the vacuum in a pulsed electric background field. Employing the Sauter-type pulsed field $E(t) = E_0 {\\rm sech}^2(t/\\tau)$ with height $E_0$ and width $\\tau$, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in the background field. In the constant field limit (the long pulse limit), Schwinger's non-perturbative formula is reproduced, while in the short pulse limit the leading-order perturbative treatment is justified. We show that two dimensionless parameters $eE_0 \\tau^2$ and $eE_0 \\tau /m_e$ characterize the importance of multiple interactions with the fields and the transition from the perturbative to the non-perturbative regime. We also reveal that pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak $|eE_0|/m_e^2 \\lesssim 1$ and the pulse duration is relatively short $m\\tau \\lesssim 1$ and that the enhancement is predominantly described by ...
Probing black holes in non-perturbative gauge theory
Iizuka, N; Lifschytz, G; Lowe, D A; Iizuka, Norihiro; Kabat, Daniel; Lifschytz, Gilad; Lowe, David A.
2002-01-01
We use a 0-brane to probe a ten-dimensional near-extremal black hole with N units of 0-brane charge. We work directly in the dual strongly-coupled quantum mechanics, using mean-field methods to describe the black hole background non-perturbatively. We obtain the distribution of W boson masses, and find a clear separation between light and heavy degrees of freedom. To localize the probe we introduce a resolving time and integrate out the heavy modes. After a non-trivial change of coordinates, the effective potential for the probe agrees with supergravity expectations. We compute the entropy of the probe, and find that the stretched horizon of the black hole arises dynamically in the quantum mechanics, as thermal restoration of unbroken U(N+1) gauge symmetry. Our analysis of the quantum mechanics predicts a correct relation between the horizon radius and entropy of a black hole.
Cryosurgery with pulsed electric fields.
Daniels, Charlotte S; Rubinsky, Boris
2011-01-01
This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to
Cryosurgery with pulsed electric fields.
Directory of Open Access Journals (Sweden)
Charlotte S Daniels
Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused
Cryosurgery with Pulsed Electric Fields
Daniels, Charlotte S.; Rubinsky, Boris
2011-01-01
This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to
Non-perturbative monodromies in N=2 heterotic string vacua
Lópes-Cardoso, G; Mohaupt, T; Cardoso, Gabriel Lopes; Lust, Dieter; Mohaupt, Thomas
1995-01-01
We address non-perturbative effects and duality symmetries in N=2 heterotic string theories in four dimensions. Specifically, we consider how each of the four lines of enhanced gauge symmetries in the perturbative moduli space of N=2 T_2 compactifications is split into 2 lines where monopoles and dyons become massless. This amounts to considering non-perturbative effects originating from enhanced gauge symmetries at the microscopic string level. We show that the perturbative and non-perturbative monodromies consistently lead to the results of Seiberg-Witten upon identication of a consistent truncation procedure from local to rigid N=2 supersymmetry.
LH and ICRH RF electric field measurements using Doppler-free Saturation Spectroscopy
Martin, E. H.; Zafar, A.; Caughman, J. B. O.; Isler, R. C.; Bell, G. L.
2016-10-01
The physics mechanisms of wave heating and current drive processes in the bulk hot plasma are generally well identified, however, details of the wave-plasma interaction in the cold plasma edge are still not fully understood. To investigate the alluding physics non-perturbative diagnostics are required due to the large energy flux traversing the space associated with the corresponding RF antenna/launcher. A spectroscopic diagnostic, based on Doppler-free saturation spectroscopy, is currently under development at ORNL that will be capable of measuring RF electric fields with high precision (20 V/cm). The RF electric field is determined by systematically fitting a Balmer series spectral line profile obtained via DFSS using a previous validated non-perturbative quantum mechanically model. The spectral line profile is measured using Doppler-free saturation spectroscopy (DFSS). DFSS is a laser-based technique involving two counter-propagating beams, referred to as the pump and probe, which are made to overlap at a single point in space. The frequency of the laser is swept over that associated with the electronic transition of interest and the probe beam absorption intensity is measured. In this presentation an active spectroscopic technique allowing for measurements of the RF electric field driving wave-plasma interactions for lower hybrid (LH) and ion cyclotron resonance heating (ICRH) systems, based on DFSS, will be discussed. Initial measurements of the electric field in the magnetized capacitively coupled RF sheath obtained on a laboratory test stand will be presented.
Electric Field Uniformity of TEPC
Institute of Scientific and Technical Information of China (English)
ZHANG; Wei-hua; WANG; Zhi-qiang; LIU; Yi-na; LI; Chun-juan; LUO; Hai-long
2012-01-01
<正>As a proportional counter, the problem with tissue-equivalent proportional counter (TEPC) is that near the end of the anode wire the wall of detector is much closer to the anode, the electric field is stronger, and the gas gain is higher than at the center of the anode, namely end effects. In order to optimize the design of TEPC, a gas-flow TEPC (Fig. 1) is designed and constructed to take the research of electric field distribution characteristics.
Revisiting the Corotation Electric Field
Rothwell, P. L.
2001-05-01
The rotation of the Earth's dipole magnetic field produces a corotation electric field in the nonrotating frame of reference. A quick calculation implies that this field might arise from the relative motion of an observer in the nonrotating frame and the motion of rotating magnetic field lines. However, upon applying Faraday's Law one finds that total time rate of change of the magnetic field as seen in the nonrotating frame is zero due to the azimuthal symmetry of the dipole. Therefore, classical EM theory(1) predicts a zero corotation electric field in the nonrotating frame for a vacuum. This conundrum has been traditionally treated in the following manner(2,3). 1) Start with a vacuum state with no conductors and plasma present. The transformation between E (the electric field in the nonrotating frame) and E' (the electric field in the rotating frame)implies that in the rotating frame E' is nonzero while E = 0. 2) In the presence of a thin conducting spherical shell (the ionosphere) polarization charges form in the shell due to the magnetic force on the electrons. A polarization electric field Ep is created such that in the idealized case the shell has a uniform electric potential. This Ep has a component along the magnetic field lines outside the shell. 3) Plasma will polarize along B, thus canceling the parallel component of Ep which allows the potential on the shell to be mapped along the magnetic field lines setting E' = 0. From the transformation equation E is now nonzero. This is the electric field required in the nonrotating frame for the plasma to corotate with the dipole. The presence of the corotation electric field is not a local result, but a nonlocal effect that requires the presence of an ionosphere and a conducting plasma. (1) W.K.H. Panofsky and M. Phillips, Classical Electricity and Magnetism, Addison-Wesley, 1956. (2) H. Alfven and C.-G. Falthammar, Cosmical Electrodynamics, 2nd ed., Oxford Press, 1963. (3) E.W.Hones and J.E.Bergeson, J. Geophys
Finite pulse effects on fermion pair creation from strong electric fields
Taya, Hidetoshi; Fujii, Hirotsugu; Itakura, Kazunori
2014-09-01
In the early stage of heavy ion collisions, there appear extraordinarily strong (color) EM fields. In the presence of such strong fields, we encounter essentially new phenomena that are not observed in the vacuum: Among those is fermion pair creation from the vacuum. In this talk, we consider fermion pair creation from the vacuum in a strong electric field with finite duration. Employing the Sauter-type pulsed electric field with height E0 and width τ, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in a strong field with finite duration. We identify that two dimensionless parameters ν = | g E0 | τ2 and γ = | g E0 | τ / m characterize the importance of multiple interactions with the field and the transition from the perturbative to the non-perturbative regime. We also show that the pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak | g E0 | / m2 < 1 and the pulse duration is relatively short mτ < 1 , and reveal that the enhancement is predominantly described by the lowest order perturbation with a single photon. We also discuss some recent developments and applications.
A Perturbative Window into Non-Perturbative Physics
Dijkgraaf, R; Dijkgraaf, Robbert; Vafa, Cumrun
2002-01-01
We argue that for a large class of N=1 supersymmetric gauge theories the effective superpotential as a function of the glueball chiral superfield is exactly given by a summation of planar diagrams of the same gauge theory. This perturbative computation reduces to a matrix model whose action is the tree-level superpotential. For all models that can be embedded in string theory we give a proof of this result, and we sketch an argument how to derive this more generally directly in field theory. These results are obtained without assuming any conjectured dualities and can be used as a systematic method to compute instanton effects: the perturbative corrections up to n-th loop can be used to compute up to n-instanton corrections. These techniques allow us to see many non-perturbative effects, such as the Seiberg-Witten solutions of N=2 theories, the consequences of Montonen-Olive S-duality in N=1* and Seiberg-like dualities for N=1 theories from a completely perturbative planar point of view in the same gauge theo...
Non-Perturbative Two-Dimensional Dilaton Gravity
Mikovic, A
1993-01-01
We present a review of the canonical quantization approach to the problem of non-perturbative 2d dilaton gravity. In the case of chiral matter we describe a method for solving the constraints by constructing a Kac-Moody current algebra. For the models of interest, the relevant Kac-Moody algebras are based on SL(2,R) X U(1) group and on an extended 2d Poincare group. As a consequence, the constraints become free-field Virasoro generators with background charges. We argue that the same happens in the non-chiral case. The problem of the corresponding BRST cohomology is discussed as well as the unitarity of the theory. One can show that the theory is unitary by chosing a physical gauge, and hence the problem of transitions from pure into mixed sates is absent. Implications for the physics of black holes are discussed. (Based on the talks presented at Trieste conference on Gauge Theories, Applied Supersymmetry and Quantum Gravity, May 1993 and at Danube '93 Workshop, Belgrade, Yugoslavia, June 1993)
THOR Electric Field Instrument - EFI
Khotyaintsev, Yuri; Bale, Stuart D.; Rothkaehl, Hanna; Bonnell, John; Åhlen, Lennart; Vaivads, Andris; Lindqvist, Per-Arne; Ivchenko, Nickolay; Soucek, Jan
2017-04-01
Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The Electric Field Instrument (EFI) is to measure the electric field vector in the frequency range 0-200 kHz. EFI consists of two sets of sensors: Spin-plane Double Probes (EFI-SDP) providing high sensitivity DC electric field in the spacecraft spin plane (2D), and the High-Frequency Antenna (EFI-HFA) providing 3D electric field at frequencies above 1 kHz. EFI-SDP consists of 4 biased spherical probes extended on 50 m long wire booms, 90 degrees apart in the spin plane, giving a 100 m baseline for each of the two spin-plane electric field components. EFI-HFA consists of 6 x 1.25 m long monopoles, forming 3 dipolar antennas crossed at 90 degrees to each other. In addition to the sensors, EFI contains HFA and SDP pre-amplifiers, as well as bias electronics boards (BEBs) hosted in the man electronics box of the Field and Wave processor (FWP). As THOR spacecraft has a sun-pointing spin axis, EFI-SDP measures the electric field in the plane approximately orthogonal to the sun using long wire booms. The sun-pointing attitude greatly reduces errors due to wake effects and asymmetric photoelectron clouds, enabling the highly accurate in comparison to earlier missions ±0.1 mV/m near-DC electric field measurements. Interferometry using the electric field probes can be used to infer wavelengths and scale sizes at the smallest scales in the plasma. EFI also measures the floating potential of the satellite, which can be used to estimate the plasma density at very high time resolution (up to a few hundred Hz). The sun-pointing attitude greatly reduces changes in the illuminated area, and hence the associated spin-dependent errors. In combination with densities derived from the observed plasma frequency emission line, EFI monitors the plasma density from DC to a few hundred Hz. EFI measurements characterize electric field and density variations associated with kinetic
Electric fields and quantum wormholes
Engelhardt, Dalit; Freivogel, Ben; Iqbal, Nabil
2015-09-01
Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "quantum wormhole." We demonstrate within low-energy effective field theory that there is a precise sense in which electric fields can also thread such quantum wormholes. We define a nonperturbative "wormhole susceptibility" that measures the ease of passing an electric field through any sort of wormhole. The susceptibility of a quantum wormhole is suppressed by powers of the U (1 ) gauge coupling relative to that for a classical wormhole but can be made numerically equal with a sufficiently large amount of entangled matter.
Synaptic Effects of Electric Fields
Rahman, Asif
Learning and sensory processing in the brain relies on the effective transmission of information across synapses. The strength and efficacy of synaptic transmission is modifiable through training and can be modulated with noninvasive electrical brain stimulation. Transcranial electrical stimulation (TES), specifically, induces weak intensity and spatially diffuse electric fields in the brain. Despite being weak, electric fields modulate spiking probability and the efficacy of synaptic transmission. These effects critically depend on the direction of the electric field relative to the orientation of the neuron and on the level of endogenous synaptic activity. TES has been used to modulate a wide range of neuropsychiatric indications, for various rehabilitation applications, and cognitive performance in diverse tasks. How can a weak and diffuse electric field, which simultaneously polarizes neurons across the brain, have precise changes in brain function? Designing therapies to maximize desired outcomes and minimize undesired effects presents a challenging problem. A series of experiments and computational models are used to define the anatomical and functional factors leading to specificity of TES. Anatomical specificity derives from guiding current to targeted brain structures and taking advantage of the direction-sensitivity of neurons with respect to the electric field. Functional specificity originates from preferential modulation of neuronal networks that are already active. Diffuse electric fields may recruit connected brain networks involved in a training task and promote plasticity along active synaptic pathways. In vitro, electric fields boost endogenous synaptic plasticity and raise the ceiling for synaptic learning with repeated stimulation sessions. Synapses undergoing strong plasticity are preferentially modulated over weak synapses. Therefore, active circuits that are involved in a task could be more susceptible to stimulation than inactive circuits
Non-perturbative effects and the refined topological string
Hatsuda, Yasuyuki; Moriyama, Sanefumi; Okuyama, Kazumi
2013-01-01
The partition function of ABJM theory on the three-sphere has non-perturbative corrections due to membrane instantons in the M-theory dual. We show that the full series of membrane instanton corrections is completely determined by the refined topological string on the Calabi-Yau manifold known as local P1xP1, in the Nekrasov-Shatashvili limit. Our result can be interpreted as a first-principles derivation of the full series of non-perturbative effects for the closed topological string on this Calabi-Yau background. Based on this, we make a proposal for the non-perturbative free energy of topological strings on general, local Calabi-Yau manifolds.
Non-perturbative effects and the refined topological string
Energy Technology Data Exchange (ETDEWEB)
Hatsuda, Yasuyuki [DESY Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Marino, Marcos [Geneve Univ. (Switzerland). Dept. de Physique Theorique et Section de Mathematiques; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst.; Nagoya Univ. (Japan). Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics
2013-06-15
The partition function of ABJM theory on the three-sphere has non-perturbative corrections due to membrane instantons in the M-theory dual. We show that the full series of membrane instanton corrections is completely determined by the refined topological string on the Calabi-Yau manifold known as local P{sup 1} x P{sup 1}, in the Nekrasov-Shatashvili limit. Our result can be interpreted as a first-principles derivation of the full series of non-perturbative effects for the closed topological string on this Calabi-Yau background. Based on this, we make a proposal for the non-perturbative free energy of topological strings on general, local Calabi-Yau manifolds.
Quark and Gluon Production from a Boost-invariantly Expanding Color Electric Field
Taya, Hidetoshi
2016-01-01
Particle production from an expanding classical color electromagnetic field is extensively studied, motivated by the early stage dynamics of ultra-relativistic heavy ion collisions. We develop a formalism at one-loop order to compute the particle spectra by canonically quantizing quark, gluon and ghost fluctuations under the presence of such an expanding classical color background field; the canonical quantization is done in the $\\tau$-$\\eta$ coordinates in order to take into account manifestly the expanding geometry. As a demonstration, we model the expanding classical color background field by a boost-invariantly expanding homogeneous color electric field with lifetime $T$, for which we obtain analytically the quark and gluon production spectra by solving the equations of motion of QCD non-perturbatively with respect to the color electric field. In this paper we study (i) finite lifetime effect which is found to modify significantly the particle spectra from those expected from the Schwinger formula; (ii) t...
Geometric transition in Non-perturbative Topological string
Sugimoto, Yuji
2016-01-01
We study a geometric transition in non-perturbative topological string. We consider two cases. One is the geometric transition from the closed topological string on the local $\\mathcal{B}_{3}$ to the closed topological string on the resolved conifold. The other is the geometric transition from the closed topological string on the local $\\mathcal{B}_{3}$ to the open topological string on the resolved conifold with a toric A-brane. We find that, in both cases, the geometric transition can be applied for the non-perturbative topological string. We also find the corrections of the value of K\\"ahler parameters at which the geometric transition occurs.
Microstickies agglomeration by electric field.
Du, Xiaotang Tony; Hsieh, Jeffery S
2016-01-01
Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.
Apparatuses and methods for generating electric fields
Scott, Jill R; McJunkin, Timothy R; Tremblay, Paul L
2013-08-06
Apparatuses and methods relating to generating an electric field are disclosed. An electric field generator may include a semiconductive material configured in a physical shape substantially different from a shape of an electric field to be generated thereby. The electric field is generated when a voltage drop exists across the semiconductive material. A method for generating an electric field may include applying a voltage to a shaped semiconductive material to generate a complex, substantially nonlinear electric field. The shape of the complex, substantially nonlinear electric field may be configured for directing charged particles to a desired location. Other apparatuses and methods are disclosed.
Special Effect of Parallel Inductive Electric Field
Institute of Scientific and Technical Information of China (English)
陈涛; 刘振兴; W.Heikkila
2002-01-01
Acceleration of electrons by a field-aligned electric field during a magnetospheric substorm in the deep geomagnetic tail is studied by means of a one-dimensional electromagnetic particle code. It was found that the free acceleration of the electrons by the parallel electric field is obvious; kinetic energy variation is greater than electromagnetic energy variation in the presence of parallel electric field. Magnetic energy is greater than kinetic energy variation and electric energy variation in the absence of the parallel electric field. More wave modes in the presence of the parallel electric field are generated than those in the absence of the parallel electric field.
Electrophoresis in strong electric fields.
Barany, Sandor
2009-01-01
Two kinds of non-linear electrophoresis (ef) that can be detected in strong electric fields (several hundred V/cm) are considered. The first ("classical" non-linear ef) is due to the interaction of the outer field with field-induced ionic charges in the electric double layer (EDL) under conditions, when field-induced variations of electrolyte concentration remain to be small comparatively to its equilibrium value. According to the Shilov theory, the non-linear component of the electrophoretic velocity for dielectric particles is proportional to the cubic power of the applied field strength (cubic electrophoresis) and to the second power of the particles radius; it is independent of the zeta-potential but is determined by the surface conductivity of particles. The second one, the so-called "superfast electrophoresis" is connected with the interaction of a strong outer field with a secondary diffuse layer of counterions (space charge) that is induced outside the primary (classical) diffuse EDL by the external field itself because of concentration polarization. The Dukhin-Mishchuk theory of "superfast electrophoresis" predicts quadratic dependence of the electrophoretic velocity of unipolar (ionically or electronically) conducting particles on the external field gradient and linear dependence on the particle's size in strong electric fields. These are in sharp contrast to the laws of classical electrophoresis (no dependence of V(ef) on the particle's size and linear dependence on the electric field gradient). A new method to measure the ef velocity of particles in strong electric fields is developed that is based on separation of the effects of sedimentation and electrophoresis using videoimaging and a new flowcell and use of short electric pulses. To test the "classical" non-linear electrophoresis, we have measured the ef velocity of non-conducting polystyrene, aluminium-oxide and (semiconductor) graphite particles as well as Saccharomice cerevisiae yeast cells as a
Linear electric field mass spectrometry
Energy Technology Data Exchange (ETDEWEB)
McComas, D.J.; Nordholt, J.E.
1991-03-29
A mass spectrometer is described having a low weight and low power requirement, for use in space. It can be used to analyze the ionized particles in the region of the spacecraft on which it is mounted. High mass resolution measurements are made by timing ions moving through a gridless cylindrically sysmetric linear electric field.
Electric fields and quantum wormholes
Engelhardt, D.; Freivogel, B.; Iqbal, N.
2015-01-01
Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a
Electric fields and quantum wormholes
Engelhardt, D.; Freivogel, B.; Iqbal, N.
2015-01-01
Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "
A non-perturbative study of massive gauge theories
DEFF Research Database (Denmark)
Della Morte, Michele; Hernandez, Pilar
2013-01-01
We consider a non-perturbative formulation of an SU(2) massive gauge theory on a space-time lattice, which is also a discretised gauged non-linear chiral model. The lattice model is shown to have an exactly conserved global SU(2) symmetry. If a scaling region for the lattice model exists and the ...
Insights on non-perturbative aspects of TMDs from models
Energy Technology Data Exchange (ETDEWEB)
H. Avakian, A. Efremov, P. Schweitzer, O. Teryaev, F. Yuan, P. Zavada
2009-12-01
Transverse momentum dependent parton distribution functions are a key ingredient in the description of spin and azimuthal asymmetries in deep-inelastic scattering processes. Recent results from non-perturbative calculations in effective approaches are reviewed, with focus on relations among different parton distribution functions in QCD and models.
Non-perturbative lorentzian quantum gravity, causality and topology change
Ambjørn, J.; Loll, R.
1998-01-01
We formulate a non-perturbative lattice model of two-dimensional Lorentzian quantum gravity by performing the path integral over geometries with a causal structure. The model can be solved exactly at the discretized level. Its continuum limit coincides with the theory obtained by quantizing 2d conti
Bardóczi, L.; Rhodes, T. L.; Carter, T. A.; Crocker, N. A.; Peebles, W. A.; Grierson, B. A.
2016-05-01
Neoclassical tearing modes (NTMs) often lead to the decrease of plasma performance and can lead to disruptions, which makes them a major impediment in the development of operating scenarios in present toroidal fusion devices. Recent gyrokinetic simulations predict a decrease of plasma turbulence and cross-field transport at the O-point of the islands, which in turn affects the NTM dynamics. In this paper, a heat transport model of magnetic islands employing spatially non-uniform cross-field thermal diffusivity (χ⊥) is presented. This model is used to derive χ⊥ at the O-point from electron temperature data measured across 2/1 NTM islands in DIII-D. It was found that χ⊥ at the O-point is 1 to 2 orders of magnitude smaller than the background plasma transport, in qualitative agreement with gyrokinetic predictions. As the anomalously large values of χ⊥ are often attributed to turbulence driven transport, the reduction of the O-point χ⊥ is consistent with turbulence reduction found in recent experiments. Finally, the implication of reduced χ⊥ at the O-point on NTM dynamics was investigated using the modified Rutherford equation that predicts a significant effect of reduced χ⊥ at the O-point on NTM saturation.
GROUNDWATER AND SOIL REMEDIATION USING ELECTRICAL FIELD
Enhancements of contaminants removal and degradation in low permeability soils by electrical fields are achieved by the processes of electrical heating, electrokinetics, and electrochemical reactions. Electrical heating increases soil temperature resulting in the increase of cont...
Elliptic CY3folds and non-perturbative modular transformation
Energy Technology Data Exchange (ETDEWEB)
Iqbal, Amer [Government College University, Abdus Salam School of Mathematical Sciences, Lahore (Pakistan); Shabbir, Khurram [Government College University, Department of Mathematics, Lahore (Pakistan)
2016-03-15
We study the refined topological string partition function of a class of toric elliptically fibered Calabi-Yau threefolds. These Calabi-Yau threefolds give rise to five dimensional quiver gauge theories and are dual to configurations of M5-M2-branes. We determine the Gopakumar-Vafa invariants for these threefolds and show that the genus g free energy is given by the weight 2 g Eisenstein series. We also show that although the free energy at all genera are modular invariant, the full partition function satisfies the non-perturbative modular transformation property discussed by Lockhart and Vafa in arXiv:1210.5909 and therefore the modularity of free energy is up to non-perturbative corrections. (orig.)
Non-perturbative String Theory from Water Waves
Energy Technology Data Exchange (ETDEWEB)
Iyer, Ramakrishnan; Johnson, Clifford V.; /Southern California U.; Pennington, Jeffrey S.; /SLAC
2012-06-14
We use a combination of a 't Hooft limit and numerical methods to find non-perturbative solutions of exactly solvable string theories, showing that perturbative solutions in different asymptotic regimes are connected by smooth interpolating functions. Our earlier perturbative work showed that a large class of minimal string theories arise as special limits of a Painleve IV hierarchy of string equations that can be derived by a similarity reduction of the dispersive water wave hierarchy of differential equations. The hierarchy of string equations contains new perturbative solutions, some of which were conjectured to be the type IIA and IIB string theories coupled to (4, 4k ? 2) superconformal minimal models of type (A, D). Our present paper shows that these new theories have smooth non-perturbative extensions. We also find evidence for putative new string theories that were not apparent in the perturbative analysis.
Importance of Non-Perturbative QCD Parameters for Bottom Mesons
Upadhyay, A
2015-01-01
The importance of non-perturbative Quantum Chromodynamics [QCD] parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two non perturbative QCD parameters used in heavy quark effective theory formula and using the best fitted parameter, masses of the excited bottom meson states in JP=(1/2)+ doublet in strange as well as non-strange sector are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass and hyperfine splitting has also been analyzed for both strange and non-strange heavy mesons with respect to spin and flavor symmetries.
Jet Extinction from Non-Perturbative Quantum Gravity Effects
Kilic, Can; Lath, Amitabh; Rose, Keith; Thomas, Scott
2012-01-01
The infrared-ultraviolet properties of quantum gravity suggest on very general grounds that hard short distance scattering processes are highly suppressed for center of mass scattering energies beyond the fundamental Planck scale. If this scale is not too far above the electroweak scale, these non-perturbative quantum gravity effects could be manifest as an extinction of high transverse momentum jets at the LHC. To model these effects we implement an Extinction Monte Carlo modification of the...
Non-perturbative inputs for gluon distributions in the hadrons
Ermolaev, B. I.; Troyan, S. I.
2017-03-01
Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K_T-and collinear factorizations.
Electric field distribution of electron emitter surfaces
Tagawa, M.; Takenobu, S.; Ohmae, N.; Umeno, M.
1987-03-01
The electric field distribution of a tungsten field emitter surface and a LaB6 thermionic emitter surface has been studied. The computer simulation of electric field distribution on the emitter surface was carried out with a charge simulation method. The electric field distribution of the LaB6 thermionic emitter was experimentally evaluated by the Schottky plot. Two independent equations are necessary for obtaining local electric field and work function; the Fowler-Nordheim equation and the equation of total energy distribution of emitted electron being used to evaluate the electric field distribution of the tungsten field emitter. The experimental results agreed with the computer simulation.
Pulsed electric field increases reproduction.
Panagopoulos, Dimitris J
2016-01-01
Purpose To study the effect of pulsed electric field - applied in corona discharge photography - on Drosophila melanogaster reproduction, possible induction of DNA fragmentation, and morphological alterations in the gonads. Materials and methods Animals were exposed to different field intensities (100, 200, 300, and 400 kV/m) during the first 2-5 days of their adult lives, and the effect on reproductive capacity was assessed. DNA fragmentation during early- and mid-oogenesis was investigated by application of the TUNEL (Terminal deoxynucleotide transferase dUTP Nick End Labeling) assay. Sections of follicles after fixation and embedding in resins were observed for possible morphological/developmental abnormalities. Results The field increased reproduction by up to 30% by increasing reproductive capacity in both sexes. The effect increased with increasing field intensities. The rate of increase diminished at the strongest intensities. Slight induction of DNA fragmentation was observed exclusively in the nurse (predominantly) and follicle cells, and exclusively at the two most sensitive developmental stages, i.e., germarium and predominantly stage 7-8. Sections of follicles from exposed females at stages of early and mid-oogennesis other than germarium and stages 7-8 did not reveal abnormalities. Conclusions (1) The specific type of electric field may represent a mild stress factor, inducing DNA fragmentation and cell death in a small percentage of gametes, triggering the reaction of the animal's reproductive system to increase the rate of gametogenesis in order to compensate the loss of a small number of gametes. (2) The nurse cells are the most sensitive from all three types of egg chamber cells. (3) The mid-oogenesis checkpoint (stage 7-8) is more sensitive to this field than the early oogenesis one (germarium) in contrast to microwave exposure. (4) Possible therapeutic applications, or applications in increasing fertility, should be investigated.
New electric field in asymmetric magnetic reconnection.
Malakit, K; Shay, M A; Cassak, P A; Ruffolo, D
2013-09-27
We present a theory and numerical evidence for the existence of a previously unexplored in-plane electric field in collisionless asymmetric magnetic reconnection. This electric field, dubbed the "Larmor electric field," is associated with finite Larmor radius effects and is distinct from the known Hall electric field. Potentially, it could be an important indicator for the upcoming Magnetospheric Multiscale mission to locate reconnection sites as we expect it to appear on the magnetospheric side, pointing earthward, at the dayside magnetopause reconnection site.
Cell separation using electric fields
Mangano, Joseph (Inventor); Eppich, Henry (Inventor)
2009-01-01
The present invention involves methods and devices which enable discrete objects having a conducting inner core, surrounded by a dielectric membrane to be selectively inactivated by electric fields via irreversible breakdown of their dielectric membrane. One important application of the invention is in the selection, purification, and/or purging of desired or undesired biological cells from cell suspensions. According to the invention, electric fields can be utilized to selectively inactivate and render non-viable particular subpopulations of cells in a suspension, while not adversely affecting other desired subpopulations. According to the inventive methods, the cells can be selected on the basis of intrinsic or induced differences in a characteristic electroporation threshold, which can depend, for example, on a difference in cell size and/or critical dielectric membrane breakdown voltage. The invention enables effective cell separation without the need to employ undesirable exogenous agents, such as toxins or antibodies. The inventive method also enables relatively rapid cell separation involving a relatively low degree of trauma or modification to the selected, desired cells. The inventive method has a variety of potential applications in clinical medicine, research, etc., with two of the more important foreseeable applications being stem cell enrichment/isolation, and cancer cell purging.
Non-perturbative QCD Modeling and Meson Physics
Nguyen, T; Tandy, P C
2009-01-01
Using a ladder-rainbow kernel previously established for light quark hadron physics, we explore the extension to masses and electroweak decay constants of ground state pseudoscalar and vector quarkonia and heavy-light mesons in the c- and b-quark regions. We make a systematic study of the effectiveness of a constituent mass concept as a replacement for a heavy quark dressed propagator for such states. The difference between vector and axial vector current correlators is explored within the same model to provide an estimate of the four quark chiral condensate and the leading distance scale for the onset of non-perturbative phenomena in QCD.
Non-perturbative QCD amplitudes in quenched and eikonal approximations
Fried, H. M.; Grandou, T.; Sheu, Y.-M.
2014-05-01
Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD.
Testing QCD in the non-perturbative regime
Energy Technology Data Exchange (ETDEWEB)
A.W. Thomas
2007-01-01
This is an exciting time for strong interaction physics. We have a candidate for a fundamental theory, namely QCD, which has passed all the tests thrown at it in the perturbative regime. In the non-perturbative regime it has also produced some promising results and recently a few triumphs but the next decade will see enormous progress in our ability to unambiguously calculate the consequences of non-perturbative QCD and to test those predictions experimentally. Amongst the new experimental facilities being constructed, the hadronic machines at JPARC and GSI-FAIR and the 12 GeV Upgrade at Jefferson Lab, the major new electromagnetic facility worldwide, present a beautifully complementary network aimed at producing precise new measurements which will advance our knowledge of nuclear systems and push our ability to calculate the consequences of QCD to the limit. We will first outline the plans at Jefferson Lab for doubling the energy of CEBAF. The new facility presents some wonderful opportunities for discovery in strong interaction physics, as well as beyond the standard model. Then we turn to the theoretical developments aimed at extracting precise results for physical hadron properties from lattice QCD simulations. This discussion will begin with classical examples, such as the mass of the nucleon and ?, before dealing with a very recent and spectacular success involving information extracted from modern parity violating electron scattering.
Non-perturbative closure calculation for fluids and plasmas
Tang, Xianzhu; McDevitt, Chris; Guo, Zehua
2015-11-01
Closure calculation of the Chapman-Enskog type is based on a perturbative expansion in the small parameter of Knudsen number, which is defined as the ratio of the thermal particle mean-free-path and the system gradient length scale. The error in the analysis can be locally measured in phase space using the local Knudsen number, which for the energy squared dependence of the mean-free-path, is much larger for high energy particles. Such breakdown, if occurs at sufficiently high energy, has small impact on closure results, but in cases of strong spatial gradients, can have large effect and invalidate the perturbative calculation. Here we show a non-perturbative closure formulation and its application in calculating standard closure quantitities such as heat flux. This approach applies as long as the thermal bulk is close to a Maxwellian, where a perturbative analysis can be matched onto a non-perturbative treatment of the tail population. Work supported by DOE via LANL-LDRD.
Tuning Photoluminescence Response by Electric Field in Electrically Soft Ferroelectrics
Khatua, Dipak Kumar; Kalaskar, Abhijeet; Ranjan, Rajeev
2016-03-01
We show that an electrically soft ferroelectric host can be used to tune the photoluminescence (PL) response of rare-earth emitter ions by external electric field. The proof of this concept is demonstrated by changing the PL response of the Eu3 + ion by electric field on a model system Eu-doped 0.94 (Na1 /2Bi1 /2TiO3)-0.06 (BaTiO3) . We also show that new channels of radiative transitions, forbidden otherwise, open up due to positional disorder in the system, which can as well be tuned by electric field.
Electric double layer of anisotropic dielectric colloids under electric fields
Han, M.; Wu, H.; Luijten, E.
2016-07-01
Anisotropic colloidal particles constitute an important class of building blocks for self-assembly directed by electrical fields. The aggregation of these building blocks is driven by induced dipole moments, which arise from an interplay between dielectric effects and the electric double layer. For particles that are anisotropic in shape, charge distribution, and dielectric properties, calculation of the electric double layer requires coupling of the ionic dynamics to a Poisson solver. We apply recently proposed methods to solve this problem for experimentally employed colloids in static and time-dependent electric fields. This allows us to predict the effects of field strength and frequency on the colloidal properties.
Decay constants of B-mesons from non-perturbative HQET with two light dynamical quarks
DEFF Research Database (Denmark)
Bernardoni, F.; Blossier, B.; Bulava, J.;
2014-01-01
We present a computation of B-meson decay constants from lattice QCD simulations within the framework of Heavy Quark Effective Theory for the b-quark. The next-to-leading order corrections in the HQET expansion are included non-perturbatively. Based on Nf=2 gauge field ensembles, covering three...... limits. Our final results read fB=186(13)MeV, fBs=224(14)MeV and fBs/fB=1.203(65). A comparison with other results in the literature does not reveal a dependence on the number of dynamical quarks, and effects from truncating HQET appear to be negligible....
Electric-field guiding of magnetic skyrmions
Energy Technology Data Exchange (ETDEWEB)
Upadhyaya, Pramey; Yu, Guoqiang; Amiri, Pedram Khalili; Wang, Kang L.
2015-10-01
We theoretically study equilibrium and dynamic properties of nanosized magnetic skyrmions in thin magnetic films with broken inversion symmetry, where an electric field couples to magnetization via spin-orbit coupling. Based on a symmetry-based phenomenology and micromagnetic simulations we show that this electric-field coupling, via renormalizing the micromagnetic energy, modifies the equilibrium properties of the skyrmion. This change, in turn, results in a significant alteration of the current-induced skyrmion motion. Particularly, the speed and direction of the skyrmion can be manipulated by designing a desired energy landscape electrically, which we describe within Thiele's analytical model and demonstrate in micromagnetic simulations including electric-field-controlled magnetic anisotropy. We additionally use this electric-field control to construct gates for controlling skyrmion motion exhibiting a transistorlike and multiplexerlike function. The proposed electric-field effect can thus provide a low-energy electrical knob to extend the reach of information processing with skyrmions.
Compact Electric- And Magnetic-Field Sensor
Winterhalter, Daniel; Smith, Edward
1994-01-01
Compact sensor measures both electric and magnetic fields. Includes both short electric-field dipole and search-coil magnetometer. Three mounted orthogonally providing triaxial measurements of electromagnetic field at frequencies ranging from near 0 to about 10 kHz.
Imaging electric field dynamics with graphene optoelectronics
Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; Tsai, Hsin-Zon; Forrester, Patrick R.; Crommie, Michael F.; Cui, Bianxiao; Wang, Feng
2016-12-01
The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.
Entanglement Generation by Electric Field Background
Ebadi, Zahra; Mirza, Behrouz
2014-01-01
The quantum vacuum is unstable under the influence of an external electric field and decays into pairs of charged particles, a process which is known as the Schwinger pair production. We propose and demonstrate that this electric field can generate entanglement. Using the Schwinger pair production for constant and pulsed electric fields, we study entanglement for scalar particles with zero spins and Dirac fermions. One can observe the variation of the entanglement produced for bosonic and fer...
Entanglement Generation by Electric Field Background
Ebadi, Zahra
2014-01-01
The quantum vacuum is unstable under the influence of an external electric field and decays into pairs of charged particles, a process which is known as the Schwinger pair production. We propose and demonstrate that this electric field can generate entanglement. Using the Schwinger pair production for constant and pulsed electric fields, we study entanglement for scalar particles with zero spins and Dirac fermions. One can observe the variation of the entanglement produced for bosonic and fermionic modes with respect to different parameters.
Plasma heating by electric field compression.
Avinash, K; Kaw, P K
2014-05-09
Plasma heating by compression of electric fields is proposed. It is shown that periodic cycles of external compression followed by the free expansion of electric fields in the plasma cause irreversible, collisionless plasma heating and corresponding entropy generation. As a demonstration of general ideas and scalings, the heating is shown in the case of a dusty plasma, where electric fields are created due to the presence of charged dust. The method is expected to work in the cases of compression of low frequency or dc electric fields created by other methods. Applications to high power laser heating of plasmas using this scheme are discussed.
Electric field domain interface in helical systems
Energy Technology Data Exchange (ETDEWEB)
Itoh, Kimitaka; Sanuki, Heiji; Toda, Shinichiro; Yokoyama, Masayuki [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I.; Yagi, Masatoshi [Kyushu Univ., Research Institute for Applied Mechanics, Kasuga, Fukuoka (Japan); Fukuyama, Atsushi [Kyoto Univ., Department of Nuclear Engineering, Kyoto (Japan)
2001-07-01
The electric field bifurcation in helical plasmas under the condition of continuous fluxes is investigated. The stationary solution of the transport equation, together with charge neutrality condition, is investigated. It is shown that the anomalous flux plays an important role in determining multiple electric field solutions. The transition to the branch with a strong positive electric field occurs when the heat flux exceeds a critical value. Condition for the presence of transition is obtained. The radial structure of the electric field domain interface is obtained. The condition that the suppression of turbulence is expected to occur is discussed. Comparison with experimental observation is briefly mentioned. (author)
Non-Perturbative Effects in 2-D String Theory or Beyond the Liouville Wall
Brustein, Ram
1997-01-01
We discuss continuous and discrete sectors in the collective field theory of $d=1$ matrix models. A canonical Lorentz invariant field theory extension of collective field theory is presented and its classical solutions in Euclidean and Minkowski space are found. We show that the discrete, low density, sector of collective field theory includes single eigenvalue Euclidean instantons which tunnel between different vacua of the extended theory. We further show that these ``stringy" instantons induce non-perturbative effective operators of strength $e^{-{1\\over g}}$ in the extended theory. The relationship of the world sheet description of string theory and Liouville theory to the effective space-time theory is explained. We also comment on the role of the discrete, low density, sector of collective field theory in that framework.
Non-perturbative QCD effects in jets at hadron colliders
Dasgupta, Mrinal; Salam, Gavin P
2008-01-01
We discuss non-perturbative QCD contributions to jet observables, computing their dependence on the jet radius R, and on the colour and transverse momentum of the parton initiating the jet. We show, using analytic QCD models of power corrections as well as Monte Carlo simulations, that hadronisation corrections grow at small values of R, behaving as 1/R, while underlying event contributions grow with the jet area as R^2. We highlight the connection between hadronisation corrections to jets and those for event shapes in e^+e^- and DIS; we note the limited dependence of our results on the choice of jet algorithm; finally, we propose several measurements in the context of which to test or implement our predictions. The results presented here reinforce the motivation for the use of a range of R values, as well as a plurality of infrared-safe jet algorithms, in precision jet studies at hadron colliders.
Non-perturbative renormalization of three-quark operators
Energy Technology Data Exchange (ETDEWEB)
Goeckeler, Meinulf [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, Roger [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Kaltenbrunner, Thomas [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)
2008-10-15
High luminosity accelerators have greatly increased the interest in semi-exclusive and exclusive reactions involving nucleons. The relevant theoretical information is contained in the nucleon wavefunction and can be parametrized by moments of the nucleon distribution amplitudes, which in turn are linked to matrix elements of local three-quark operators. These can be calculated from first principles in lattice QCD. Defining an RI-MOM renormalization scheme, we renormalize three-quark operators corresponding to low moments non-perturbatively and take special care of the operator mixing. After performing a scheme matching and a conversion of the renormalization scale we quote our final results in the MS scheme at {mu}=2 GeV. (orig.)
Casimir operator dependences of non-perturbative fermionic QCD amplitudes
Fried, H M; Hofmann, R
2015-01-01
In eikonal and quenched approximation, it is argued that the strong coupling fermionic QCD Green's functions and related amplitudes, when based on the newly discovered effective locality property, depart from a sole dependence on the SUc(3) quadratic Casimir operator, evaluated over the fundamental gauge group representation.Though noticed in non-relativistic Quark Models, an additional dependence on the cubic Casimir operator is in contradistinction with perturbation theory, and also with a number of non-perturbative approaches such as the MIT Bag, the Stochastic Vacuum Models and lattice simulations. It accounts for the full algebraic content of the rank-2 Lie algebra of SUc(3). We briefly discuss the orders of magnitude of quadratic and cubic Casimir operator contributions.
Non-perturbative QCD amplitudes in quenched and eikonal approximations
Energy Technology Data Exchange (ETDEWEB)
Fried, H.M. [Physics Department, Brown University, Providence, RI 02912 (United States); Grandou, T., E-mail: Thierry.Grandou@inln.cnrs.fr [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France); Sheu, Y.-M., E-mail: ymsheu@alumni.brown.edu [Université de Nice-Sophia Antipolis, Institut Non Linéaire de Nice, UMR 6618 CNRS 7335, 1361 routes des Lucioles, 06560 Valbonne (France)
2014-05-15
Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. - Highlights: • We discuss the physical insight of effective locality to QCD fermionic amplitudes. • We show that an unavoidable delta function goes along with the effective locality property. • The generic structure of QCD fermion amplitudes is obtained through Random Matrix calculus.
Non-perturbative Thermodynamics in Matrix String Theory
Peñalba, J P
1999-01-01
A study of the thermodynamics in IIA Matrix String Theory is presented. The free string limit is calculated and seen to exactly reproduce the usual result. When energies are enough to excite non-perturbative objects like D-particles and specially membranes, the situation changes because they add a large number of degrees of freedom that do not appear at low energies. There seems to be a negative specific heat (even in the Microcanonical Ensemble) that moves the asymptotic temperature to zero. Besides, the mechanism of interaction and attachment of open strings to D-particles and D-membranes is analyzed. A first approach to type IIB Matrix String is carried out: its spectrum is found in the (2+1)-SYM and used to calculate an SL(2,Z) invariant partition function.
PREFACE: Loops 11: Non-Perturbative / Background Independent Quantum Gravity
Mena Marugán, Guillermo A.; Barbero G, J. Fernando; Garay, Luis J.; Villaseñor, Eduardo J. S.; Olmedo, Javier
2012-05-01
Loops 11 The international conference LOOPS'11 took place in Madrid from the 23-28 May 2011. It was hosted by the Instituto de Estructura de la Materia (IEM), which belongs to the Consejo Superior de Investigaciones Cientĺficas (CSIC). Like previous editions of the LOOPS meetings, it dealt with a wealth of state-of-the-art topics on Quantum Gravity, with special emphasis on non-perturbative background-independent approaches to spacetime quantization. The main topics addressed at the conference ranged from the foundations of Quantum Gravity to its phenomenological aspects. They encompassed different approaches to Loop Quantum Gravity and Cosmology, Polymer Quantization, Quantum Field Theory, Black Holes, and discrete approaches such as Dynamical Triangulations, amongst others. In addition, this edition celebrated the 25th anniversary of the introduction of the now well-known Ashtekar variables and the Wednesday morning session was devoted to this silver jubilee. The structure of the conference was designed to reflect the current state and future prospects of research on the different topics mentioned above. Plenary lectures that provided general background and the 'big picture' took place during the mornings, and the more specialised talks were distributed in parallel sessions during the evenings. To be more specific, Monday evening was devoted to Shape Dynamics and Phenomenology Derived from Quantum Gravity in Parallel Session A, and to Covariant Loop Quantum Gravity and Spin foams in Parallel Session B. Tuesday's three Parallel Sessions dealt with Black Hole Physics and Dynamical Triangulations (Session A), the continuation of Monday's session on Covariant Loop Quantum Gravity and Spin foams (Session B) and Foundations of Quantum Gravity (Session C). Finally, Thursday and Friday evenings were devoted to Loop Quantum Cosmology (Session A) and to Hamiltonian Loop Quantum Gravity (Session B). The result of the conference was very satisfactory and enlightening. Not
Electric field soundings through thunderstorms
Marshall, Thomas C.; Rust, W. D.
1991-01-01
Twelve balloon soundings of the electric field in thunderstorms are reported. The maximum magnitude of E in the storms averaged 96 +/-28 kV/m, with the largest being 146 kV/m. The maximum was usually observed between vertically adjacent regions of opposite charge. Using a 1D approximation to Gauss' law, four to ten charge regions in the storms are inferred. The magnitude of the density in the charge regions varied between 0.2 and 13 nC/cu m. The vertical extent of the charge regions ranged from 130 to 2100 m. None of the present 12 storms had charge distributions that fit the long-accepted model of Simpson et al. (1937, 1941) of a lower positive charge, a main negative charge, and an upper positive charge. In addition to regions similar to the Simpson model, the present storms had screening layers at the upper and lower cloud boundaries and extra charge regions, usually in the lower part of the cloud.
Non-perturbative effects of vacuum energy on the recent expansion of the universe
Parker, L; Parker, Leonard; Raval, Alpan
1999-01-01
We show that the vacuum energy of a free quantized field of very low mass can significantly alter the recent expansion of the universe. The effective action of the theory is obtained from a non-perturbative sum of scalar curvature terms in the propagator. We numerically investigate the semiclassical Einstein equations derived from it. As a result of non-perturbative quantum effects, the scalar curvature of the matter-dominated universe stops decreasing and approaches a constant value. The universe in our model evolves from an open matter-dominated epoch to a mildly inflating de Sitter expansion. The Hubble constant during the present de Sitter epoch, as well as the time at which the transition occurs from matter-dominated to de Sitter expansion, are determined by the mass of the field and by the present matter density. The model provides a theoretical explanation of the observed recent acceleration of the universe, and gives a good fit to data from high-redshift Type Ia supernovae, with a mass of about 10^{-3...
Directed cell movement in pulsed electric fields.
Franke, K; Gruler, H
1994-01-01
Human granulocytes exposed to pulsed electric guiding fields were investigated. The trajectories were determined from digitized pictures (phase contrast). The basic results are: (i) No directed response was induced by pulsed electric guiding fields having a zero averaged field. (ii) A directed response was induced by pulsed electric guiding fields having a non-zero averaged field. (iii) The directed response was enhanced for pulse sequences having a repetition time of 8 s. (iv) The lag-time between signal recognition and cellular response was 8-10 s. The results are discussed in the framework of a self-ignition model.
Non-perturbative four-wave mixing in InSb with intense off-resonant multi-THz pulses
Directory of Open Access Journals (Sweden)
Huber R.
2013-03-01
Full Text Available High-field multi-THz pulses are employed to analyze the coherent nonlinear response of the narrow-gap semiconductor InSb which is driven off-resonantly. Field-resolved four-wave mixing signals manifest the onset of a non-perturbative regime of Rabi flopping at external amplitudes above 5 MV/cm per pulse. Simulations based on a two-level quantum system confirm these experimental results.
Electric Potential and Electric Field Imaging with Applications
Generazio, Ed
2016-01-01
The technology and techniques for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field may be used for (illuminating) volumes to be inspected with EFI. The baseline sensor technology, electric field sensor (e-sensor), and its construction, optional electric field generation (quasistatic generator), and current e-sensor enhancements (ephemeral e-sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution, creating a new field of study that embraces areas of interest including electrostatic discharge mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, inspection of containers, inspection for hidden objects, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.
Pulsed electric field inactivation in a microreactor
Fox, M.B.
2006-01-01
Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar
Classical theory of electric and magnetic fields
Good, Roland H
1971-01-01
Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma
Rotating artificial gauge magnetic and electric fields
Lembessis, V E; Alshamari, S; Siddig, A; Aldossary, O M
2016-01-01
We consider the creation of artificial gauge magnetic and electric fields created when a two-level atom interacts with an optical Ferris wheel light field.These fields have the spatial structure of the optical Ferris wheel field intensity profile. If this optical field pattern is made to rotate in space then we have the creation of artificial electromagnetic fields which propagate in closed paths. The properties of such fields are presented and discussed
Nanorod dynamics in ac electric fields
Energy Technology Data Exchange (ETDEWEB)
Ruda, H E; Shik, A [Centre for Advanced Nanotechnology, University of Toronto, Toronto, M5S 3E3 (Canada)
2010-06-11
Metal and semiconductor nanorods polarized by an external electric field tend to align parallel to this field. We derived the equation of motion for this alignment, taking into account electrostatic forces, thermal fluctuations and viscous resistance of the liquid the nanorods are suspended in. It was solved for a strong ac electric field, as well as for the combination of strong dc and weak ac fields. The results were used for calculations of the capacity of the nanorod solution, its frequency dispersion and dependence on the field strength. Modification of the nanorod absorption spectra under the influence of an electric field was also considered. It was shown that metal nanorods in laser radiation, with the frequency belonging to the interval between longitudinal and transverse plasmon modes, tend to align perpendicular, rather than parallel, to the optical electric field.
Sensing electric fields using single diamond spins
Dolde, Florian; Doherty, Marcus W; Nöbauer, Tobias; Rempp, Florian; Balasubramanian, Gopalakrishnan; Wolf, Thomas; Reinhard, Friedemann; Hollenberg, Lloyd C L; Jelezko, Fedor; Wrachtrup, Jörg
2011-01-01
The ability to sensitively detect charges under ambient conditions would be a fascinating new tool benefitting a wide range of researchers across disciplines. However, most current techniques are limited to low-temperature methods like single-electron transistors (SET), single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we open up a new quantum metrology technique demonstrating precision electric field measurement using a single nitrogen-vacancy defect centre(NV) spin in diamond. An AC electric field sensitivity reaching ~ 140V/cm/\\surd Hz has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~ 150 nm from our spin sensor with averaging for one second. By careful analysis of the electronic structure of the defect centre, we show how an applied magnetic field influences the electric field sensing properties. By this we demonstrate that diamond defect centre spins can be switched between electric and magneti...
Electric Field Generation in Martian Dust Devils
Barth, Erika L.; Farrell, William M.; Rafkin, Scot C. R.
2015-01-01
Terrestrial dust devils are known to generate electric fields from the vertical separation of charged dust particles. The particles present within the dust devils on Mars may also be subject to similar charging processes and so likely contribute to electric field generation there as well. However, to date, no Marsin situ instrumentation has been deployed to measure electric field strength. In order to explore the electric environment of dust devils on Mars, the triboelectric dust charging physics from the MacroscopicTriboelectric Simulation (MTS) code has been coupled to the Mars Regional Atmospheric ModelingSystem (MRAMS). Using this model, we examine how macroscopic electric fields are generated within martian dust disturbances and attempt to quantify the time evolution of the electrodynamical system.Electric fields peak for several minutes within the dust devil simulations. The magnitude of the electric field is a strong function of the size of the particles present, the average charge on the particles and the number of particles lifted. Varying these parameters results in peak electric fields between tens of millivolts per meter and tens of kilovolts per meter.
Non-Perturbative Asymptotic Improvement of Perturbation Theory and Mellin-Barnes Representation
Directory of Open Access Journals (Sweden)
Samuel Friot
2010-10-01
Full Text Available Using a method mixing Mellin-Barnes representation and Borel resummation we show how to obtain hyperasymptotic expansions from the (divergent formal power series which follow from the perturbative evaluation of arbitrary ''N-point'' functions for the simple case of zero-dimensional φ4 field theory. This hyperasymptotic improvement appears from an iterative procedure, based on inverse factorial expansions, and gives birth to interwoven non-perturbative partial sums whose coefficients are related to the perturbative ones by an interesting resurgence phenomenon. It is a non-perturbative improvement in the sense that, for some optimal truncations of the partial sums, the remainder at a given hyperasymptotic level is exponentially suppressed compared to the remainder at the preceding hyperasymptotic level. The Mellin-Barnes representation allows our results to be automatically valid for a wide range of the phase of the complex coupling constant, including Stokes lines. A numerical analysis is performed to emphasize the improved accuracy that this method allows to reach compared to the usual perturbative approach, and the importance of hyperasymptotic optimal truncation schemes.
Threshold electric field in unconventional density waves
Dóra, Balázs; Virosztek, Attila; Maki, Kazumi
2001-07-01
As it is well known most charge-density waves (CDW's) and spin-density waves exhibit nonlinear transport with well-defined threshold electric field ET. Here we study theoretically the threshold electric field of unconventional density waves. We find that the threshold field increases monotonically with temperature without divergent behavior at Tc, unlike the one in conventional CDW. The present result in the three-dimensional weak pinning limit appears to describe rather well the threshold electric field observed recently in the low-temperature phase of α-(BEDT-TTF)2KHg(SCN)4.
Topological string theory, modularity and non-perturbative physics
Energy Technology Data Exchange (ETDEWEB)
Rauch, Marco
2011-09-15
In this thesis the holomorphic anomaly of correlators in topological string theory, matrix models and supersymmetric gauge theories is investigated. In the first part it is shown how the techniques of direct integration known from topological string theory can be used to solve the closed amplitudes of Hermitian multi-cut matrix models with polynomial potentials. In the case of the cubic matrix model, explicit expressions for the ring of non-holomorphic modular forms that are needed to express all closed matrix model amplitudes are given. This allows to integrate the holomorphic anomaly equation up to holomorphic modular terms that are fixed by the gap condition up to genus four. There is an one-dimensional submanifold of the moduli space in which the spectral curve becomes the Seiberg-Witten curve and the ring reduces to the non-holomorphic modular ring of the group {gamma}(2). On that submanifold, the gap conditions completely fix the holomorphic ambiguity and the model can be solved explicitly to very high genus. Using these results it is possible to make precision tests of the connection between the large order behavior of the 1/N expansion and non-perturbative effects due to instantons. Finally, it is argued that a full understanding of the large genus asymptotics in the multi-cut case requires a new class of non-perturbative sectors in the matrix model. In the second part a holomorphic anomaly equation for the modified elliptic genus of two M5-branes wrapping a rigid divisor inside a Calabi-Yau manifold is derived using wall-crossing formulae and the theory of mock modular forms. The anomaly originates from restoring modularity of an indefinite theta-function capturing the wall-crossing of BPS invariants associated to D4- D2-D0 brane systems. The compatibility of this equation with anomaly equations previously observed in the context of N=4 topological Yang-Mills theory on P{sup 2} and E-strings obtained from wrapping M5-branes on a del Pezzo surface which in
ELECTRIC AND MAGNETIC FIELDS ELECTRIC AND GASOLINE-POWERED VEHICLES.
Tell, Richard A; Kavet, Robert
2016-12-01
Measurements were conducted to investigate electric and magnetic fields (EMFs) from 120 Hz to 10 kHz and 1.2 to 100 kHz in 9 electric or hybrid vehicles and 4 gasoline vehicles, all while being driven. The range of fields in the electric vehicles enclosed the range observed in the gasoline vehicles. Mean magnetic fields ranged from nominally 0.6 to 3.5 µT for electric/hybrids depending on the measurement band compared with nominally 0.4 to 0.6 µT for gasoline vehicles. Mean values of electric fields ranged from nominally 2 to 3 V m(-1) for electric/hybrid vehicles depending on the band, compared with 0.9 to 3 V m(-1) for gasoline vehicles. In all cases, the fields were well within published exposure limits for the general population. The measurements were performed with Narda model EHP-50C/EHP-50D EMF analysers that revealed the presence of spurious signals in the EHP-50C unit, which were resolved with the EHP-50D model.
The Electric Field of a Weakly Electric Fish
Rasnow, Brian K.
Freshwater fish of the genus Apteronotus (family Gymnotidae) generate a weak, high frequency electric field (electroreception. Temporal jitter of the periodic field is less than 1 musec. However, electrocyte activity is not globally synchronous along the fish's electric organ. The propagation of electrocyte activation down the fish's body produces a rotation of the electric field vector in the caudal part of the fish. This may assist the fish in identifying nonsymmetrical objects, and could also confuse electrosensory predators that try to locate Apteronotus by following its fieldlines. The propagation also results in a complex spatiotemporal pattern of the EOD potential near the fish. Visualizing the potential on the same and different fish over timescales of several months suggests that it is stable and could serve as a unique signature for individual fish. Measurements of the electric field were used to calculate the effects of simple objects on the fish's electric field. The shape of the perturbation or "electric image" on the fish's skin is relatively independent of a simple object's size, conductivity, and rostrocaudal location, and therefore could unambiguously determine object distance. The range of electrolocation may depend on both the size of objects and their rostrocaudal location. Only objects with very large dielectric constants cause appreciable phase shifts, and these are strongly dependent on the water conductivity.
Interaction Between Flames and Electric Fields Studied
Yuan, Zeng-Guang; Hegde, Uday
2003-01-01
The interaction between flames and electric fields has long been an interesting research subject that has theoretical importance as well as practical significance. Many of the reactions in a flame follow an ionic pathway: that is, positive and negative ions are formed during the intermediate steps of the reaction. When an external electric field is applied, the ions move according to the electric force (the Coulomb force) exerted on them. The motion of the ions modifies the chemistry because the reacting species are altered, it changes the velocity field of the flame, and it alters the electric field distribution. As a result, the flame will change its shape and location to meet all thermal, chemical, and electrical constraints. In normal gravity, the strong buoyant effect often makes the flame multidimensional and, thus, hinders the detailed study of the problem.
Local electric field measurements by optical tweezers
Directory of Open Access Journals (Sweden)
G. Pesce
2011-09-01
Full Text Available We report a new technique to measure direction and amplitude of electric fields generated by microelectrodes embedded in polar liquid environment, as often used in microfluidic devices. The method is based on optical tweezers which act as sensitive force transducer while a trapped charged microsphere behaves as a probe. When an electric field is applied the particles moves from its equilibrium position and finishes in a new equilibrium position where electric and optical forces are balanced. A trapped bead is moved to explore the electric field in a wide region around the microelectrodes. In such way maps of electric fields with high spatial resolution can be reconstructed even for complex electrode geometries where numerical simulation approaches can fail. Experimental results are compared with calculations based on finite element analysis simulation.
Field distribution of epidural electrical stimulation.
Xie, Xiaobo; Cui, Hong yan; Xu, Shengpu; Hu, Yong
2013-11-01
Epidural electrical stimulation has been applied in clinics for many years. However, there is still a concern about possible injury to spinal nerves. This study investigated electrical field and current density distribution during direct epidural electrical stimulation. Field distribution models were theoretically deduced, while the distribution of potentials and current were analyzed. The current density presented an increase of 70-80%, with one peak value ranging from -85° to 85° between the two stimulated poles. The effect of direct epidural electrical stimulation is mainly on local tissue surrounding the electrodes, concentrated around the two stimulated positions. © 2013 Elsevier Ltd. All rights reserved.
Nucleon resonance electrocouplings in the non-perturbative regime
Energy Technology Data Exchange (ETDEWEB)
Philip L. Cole, Viktor Mokeev, Ralf Gothe
2012-09-01
There is an extensive search for baryon resonances using the CLAS detector in Hall B of JLab. Extracting the transition helicity amplitudes (or the {gamma}{sub v}NN* photo- and electrocouplings) sheds light on nature of the non-perturbative strong interaction. We have extended the data on differential cross sections to Q{sup 2} = 6.0 GeV{sup 2} for the {pi}N electroproduction channel. Electroproduction data were also collected on the two-charged-pion channel off protons, which provides nine independent differential {pi}{sup +}{pi}{sup -}p cross sections at Q{sup 2} up to 1.5 GeV{sup 2}. The two-pion results, moreover, are consistent with those from independent {pi}N electroproduction analyses, where the background contributions in the two-pion channel are completely different from that of the single-pion one. A phenomenological approach developed at Jefferson Lab - Moscow State University is employed for separating the resonant and non-resonant contributions to the final state. The Q{sup 2}-dependent electrocouplings were then obtained for the P{sub 11}(1440) and D{sub 13}(1520) excited baryon states. The new data will be discussed in light of these new developments in systematically exploring the affects of meson-baryon dressing on the transition helicity amplitudes as a function of Q{sup 2}.
Magnetotail electric fields observed from lunar orbit
Mccoy, J. E.; Lin, R. P.; Mcguire, R. E.; Chase, L. M.; Anderson, K. A.
1975-01-01
Direct observations of convection electric fields in the earth's magnetotail are reported. The electric fields have been measured from lunar orbit by detection of the E x B/B-squared drift displacement of low-energy electrons at the limb of the moon. It is found that electric fields range in magnitude from a value less than or equal to 0.02 mV/m, the limit of sensitivity of the method, to 2 mV/M. The typical value is 0.15 mV/M, and the corresponding convection velocity is 15 km/s. The sense of the electric field is almost always dawn to dusk. The electric field is often variable on a time scale of hours and sometimes minutes. The observations indicate that the electric field is not uniform across the magnetotail. If it is assumed that the typical measured electric-field value represents an average over the inhomogeneities, the potential drop across the entire tail is of the order of 40 kV.
Molecular dynamics in high electric fields
Apostol, M.; Cune, L. C.
2016-06-01
Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called "dipolons"); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.
Towards a non-perturbative construction of the operator product expansion
Energy Technology Data Exchange (ETDEWEB)
Holland, Jan [Universitaet Leipzig (Germany)
2016-07-01
Our current understanding of Quantum Field Theory (QFT) is based to a large extent on perturbative - i.e. approximate - methods. Exact constructions in QFT are not only of fundamental conceptual interest, but they offer insights into physical phenomena that are intractable by perturbative means. In this talk, I present progress on a novel approach towards the non-perturbative construction of the Operator Product Expansion (OPE). The OPE is a structure encoding the complete algebraic skeleton as well as the short distance properties of a Quantum Field Theory. Our construction method is based on a recently found recursion formula for the OPE, which is discussed along with recent results on mathematical properties of the OPE in perturbation theory.
Integrability and non-perturbative effects in the AdS/CFT correspondence
Gómez, C; Gómez, César; Hernández, Rafael
2007-01-01
We present a non-perturbative resummation of the asymptotic strong-coupling expansion for the dressing phase factor of the AdS_5xS^5 string S-matrix. The non-perturbative resummation provides a general form for the coefficients in the weak-coupling expansion, in agreement with crossing symmetry and transcendentality. The ambiguities of the non-perturbative prescription are discussed together with the similarities with the non-perturbative definition of the c=1 matrix model.
Numerical Study of Electric Field Enhanced Combustion
Han, Jie
2016-12-26
Electric fields can be used to change and control flame properties, for example changing flame speed, enhancing flame stability, or reducing pollutant emission. The ions generated in flames are believed to play the primary role. Although experiments have been carried out to study electric field enhanced combustion, they are not sufficient to explain how the ions in a flame are affected by an electric field. It is therefore necessary to investigate the problem through numerical simulations. In the present work, the electric structure of stabilized CH4/air premixed flames at atmospheric pressure within a direct current field is studied using numerical simulations. This study consists of three parts. First, the transport equations are derived from the Boltzmann kinetic equation for each individual species. Second, a general method for computing the diffusivity and mobility of ions in a gas mixture is introduced. Third, the mechanisms for neutral and charged species are improved to give better predictions of the concentrations of charged species, based on experimental data. Following from this, comprehensive numerical results are presented, including the concentrations and fluxes of charged species, the distributions of the electric field and electric potential, and the electric current-voltage relation. Two new concepts introduced with the numerical results are the plasma sheath and dead zone in the premixed flame. A reactive plasma sheath and a Boltzmann relation sheath are discovered in the region near the electrodes. The plasma sheath penetrates into the flame gas when a voltage is applied, and penetrating further if the voltage is higher. The zone outside the region of sheath penetration is defined as the dead zone. With the two concepts, analytical solutions for the electric field, electric potential and current-voltage curve are derived. The solutions directly describe the electric structure of a premixed flame subject to a DC field. These analytical solutions
Gavrilov, S P; 10.1140/epjc/s10052-009-1135-7
2009-01-01
Recently the paper "Schwinger Mechanism for Gluon Pair Production in the Presence of Arbitrary Time Dependent Chromo-Electric Field" by G. C. Nayak was published [Eur. Phys. J. C 59, 715 (2009); arXiv:0708.2430]. Its aim is to obtain an exact expression for the probability of non-perturbative gluon pair production per unit time per unit volume and per unit transverse momentum in an arbitrary time-dependent chromo-electric background field. We believe that the obtained expression is open to question. We demonstrate its inconsistency on some well-known examples. We think that this is a consequence of using the so-called "shift theorem" [arXiv:hep-th/0609192] in deriving the expression for the probability. We make some critical comments on the theorem and its applicability to the problem in question.
Introduction to power-frequency electric and magnetic fields.
1993-01-01
This paper introduces the reader to electric and magnetic fields, particularly those fields produced by electric power systems and other sources using frequencies in the power-frequency range. Electric fields are produced by electric charges; a magnetic field also is produced if these charges are in motion. Electric fields exert forces on other charges; if in motion, these charges will experience magnetic forces. Power-frequency electric and magnetic fields induce electric currents in conduct...
Electric field imaging of single atoms
Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi
2017-01-01
In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629
Electric field imaging of single atoms.
Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi
2017-05-30
In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures.
Holomorphic couplings in non-perturbative string compactifications
Energy Technology Data Exchange (ETDEWEB)
Klevers, Denis Marco
2011-06-15
In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z{sub 3}, that is canonically constructed from the original five-brane and Calabi-Yau threefold Z{sub 3} via a blow-up. We exploit the use of the blow-up threefold Z{sub 3} as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z{sub 3} as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z{sub 3}, that is generated dynamically by the five-brane backreaction. (orig.)
Electric field control of the magnetocaloric effect.
Gong, Yuan-Yuan; Wang, Dun-Hui; Cao, Qing-Qi; Liu, En-Ke; Liu, Jian; Du, You-Wei
2015-02-04
Through strain-mediated magnetoelectric coupling, it is demonstrated that the magnetocaloric effect of a ferromagnetic shape-memory alloy can be controlled by an electric field. Large hysteresis and the limited operating temperature region are effectively overcome by applying an electric field on a laminate comprising a piezoelectric and the alloy. Accordingly, a model for an active magnetic refrigerator with high efficiency is proposed in principle.
Swarm equatorial electric field chain: First results
Alken, P; Maus, S.; A. Chulliat; Vigneron, P.; Sirol, O.; Hulot, G.
2015-01-01
International audience; The eastward equatorial electric field (EEF) in the E region ionosphere drives many important phenomena at low latitudes. We developed a method of estimating the EEF from magnetometer measurements of near-polar orbiting satellites as they cross the magnetic equator, by recovering a clean signal of the equatorial electrojet current and modeling the observed current to determine the electric field present during the satellite pass. This algorithm is now implemented as an...
A Non-Perturbative Gauge-Invariant QCD: Ideal vs. Realistic QCD
Fried, H M; Sheu, Y -M
2011-01-01
A basic distinction, long overlooked, between the conventional, "idealistic" formulation of QCD, and a more "realistic" formulation is brought into focus by a rigorous, non-perturbative, gauge-invariant evaluation of the Schwinger solution for the QCD generating functional in terms of exact Fradkin representations for the Green's functional $\\mathbf{G}_{c}(x,y|A)$ and the vacuum functional $\\mathbf{L}[A]$. The quanta of all (Abelian) quantized fields may be expected to obey standard quantum-mechanical measurement properties, perfect position dependence at the cost of unknown momenta, and vice-versa, but this is impossible for quarks since they always appear asymptotically in bound states, and their transverse position or momenta can never, in principle, be exactly measured. Violation of this principle produces an absurdity in the exact evaluation of each and every QCD amplitude. We here suggest a phenomenological change in the basic QCD Lagrangian, such that a limitation of transverse precision is automatical...
Enea Romano, Antonio; Sanes Negrete, Sergio; Sasaki, Misao; Starobinsky, Alexei A.
2014-06-01
We study effects on the luminosity distance of a local inhomogeneity seeded by primordial curvature perturbations of the type predicted by the inflationary scenario and constrained by the cosmic microwave background radiation. We find that a local underdensity originated from a one, two or three standard deviations peaks of the primordial curvature perturbations field can induce corrections to the value of a cosmological constant of the order of 0.6{%},1{%},1.5{%} , respectively. These effects cannot be neglected in the precision cosmology era in which we are entering. Our results can be considered an upper bound for the effect of the monopole component of the local non-linear structure which can arise from primordial curvature perturbations and requires a fully non-perturbative relativistic treatment.
Constraining a fourth generation of quarks. Non-perturbative Higgs boson mass bounds
Energy Technology Data Exchange (ETDEWEB)
Bulava, J. [European Lab. for Particle Physics (CERN), Geneva (Switzerland); Jansen, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Nagy, A. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik
2013-01-15
We present a non-perturbative determination of the upper and lower Higgs boson mass bounds with a heavy fourth generation of quarks from numerical lattice computations in a chirally symmetric Higgs-Yukawa model. We find that the upper bound only moderately rises with the quark mass while the lower bound increases significantly, providing additional constraints on the existence of a straight-forward fourth quark generation. We examine the stability of the lower bound under the addition of a higher dimensional operator to the scalar field potential using perturbation theory, demonstrating that it is not significantly altered for small values of the coupling of this operator. For a Higgs boson mass of {proportional_to}125 GeV we find that the maximum value of the fourth generation quark mass is {proportional_to}300 GeV, which is already in conflict with bounds from direct searches.
Inspecting non-perturbative contributions to the Entanglement Entropy via wavefunctions
Bhattacharyya, Arpan; Lau, P H C; Liu, Si-Nong
2016-01-01
In this paper, we would like to systematically explore the implications of non-perturbative effects on entanglement in a many body system. Instead of pursuing the usual path-integral method in a singular space, we attempt to study the wavefunctions in detail. We begin with a toy model of multiple particles whose interaction potential admits multiple minima. We study the entanglement of the true ground state after taking the tunnelling effects into account and find some simple patterns. Notably, in the case of multiple particle interactions, entanglement entropy generically decreases with increasing number of minima. The knowledge of the subsystem actually increases as the number of minima increases. The reduced density matrix can also be seen to have close connections with graph spectra. In a more careful study of the two-well tunnelling system, we also extract the exponentially suppressed tail contribution, the analogues of instantons. To understand the effects of multiple minima in a field theory, it inspir...
Truthing the stretch: Non-perturbative cosmological realizations with multiscale spherical collapse
Neyrinck, Mark C
2015-01-01
Here we present a simple, parameter-free, non-perturbative algorithm that gives low-redshift cosmological particle realizations accurate to few-Megaparsec scales, called muscle (MUltiscale Spherical ColLapse Evolution). It has virtually the same cost as producing N-body-simulation initial conditions, since it works with the 'stretch' parameter {\\psi}, the Lagrangian divergence of the displacement field. It promises to be useful in quickly producing mock catalogs, and to simplify computationally intensive reconstructions of galaxy surveys. muscle applies a spherical-collapse prescription on multiple Gaussian-smoothed scales. It achieves higher accuracy than perturbative schemes (Zel'dovich and 2LPT), and, by including the void-in-cloud process (voids in large-scale collapsing regions), solves problems with a single-scale spherical-collapse scheme. Additionally, we show the behavior of {\\psi} for different morphologies (voids, walls, filaments, and haloes). A Python code to produce these realizations is availab...
Time-dependent backgrounds of 2D string theory: Non-perturbative effects
Alexandrov, S Yu; Alexandrov, Sergei Yu.; Kostov, Ivan K.
2005-01-01
We study the non-perturbative corrections (NPC) to the partition function of a compactified 2D string theory in a time-dependent background generated by a tachyon source. The sine-Liouville deformation of the theory is a particular case of such a background. We calculate the leading as well as the subleading NPC using the dual description of the string theory as matrix quantum mechanics. As in the minimal string theories, the NPC are classified by the double points of a complex curve. We calculate them by two different methods: by solving Toda equation and by evaluating the quasiclassical fermion wave functions. We show that the result can be expressed in terms of correlation functions of the bosonic field associated with the tachyon source and identify the leading and the subleading corrections as the contributions from the one-point (disk) and two-point (annulus) correlation functions.
Non-perturbative studies of N = 2 conformal quiver gauge theories
Energy Technology Data Exchange (ETDEWEB)
Ashok, S.K.; Dell' Aquila, E.; John, R.R. [Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai (India); Billo, M.; Frau, M.; Lerda, A. [Universita di Torino, Dipartimento di Fisica (Italy); I.N.F.N., Sezione di Torino (Italy)
2015-05-01
We study N = 2 super-conformal field theories in four dimensions that correspond to mass-deformed linear quivers with n gauge groups and (bi-)fundamental matter. We describe them using Seiberg-Witten curves obtained from an M-theory construction and via the AGT correspondence. We take particular care in obtaining the detailed relation between the parameters appearing in these descriptions and the physical quantities of the quiver gauge theories. This precise map allows us to efficiently reconstruct the non-perturbative prepotential that encodes the effective IR properties of these theories. We give explicit expressions in the cases n = 1, 2, also in the presence of an Ω-background in the Nekrasov-Shatashvili limit. All our results are successfully checked against those of the direct microscopic evaluation of the prepotential a la Nekrasov using localization methods. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
GEM Detector Electric Field Simulation
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
GEM (Gas Electron Multiplier) detectors have been widely employed in the experimental field of high energy physics and nuclear physics. As a successor to drift chambers, GEMs are much easier to fabricate and have a much higher spatial resolution
Midday reversal of equatorial ionospheric electric field
Directory of Open Access Journals (Sweden)
R. G. Rastogi
Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.
Stability of Spherical Vesicles in Electric Fields
2010-01-01
The stability of spherical vesicles in alternating (ac) electric fields is studied theoretically for asymmetric conductivity conditions across their membranes. The vesicle deformation is obtained from a balance between the curvature elastic energies and the work done by the Maxwell stresses. The present theory describes and clarifies the mechanisms for the four types of morphological transitions observed experimentally on vesicles exposed to ac fields in the frequency range from 500 to 2 × 107 Hz. The displacement currents across the membranes redirect the electric fields toward the membrane normal to accumulate electric charges by the Maxwell−Wagner mechanism. These accumulated electric charges provide the underlying molecular mechanism for the morphological transitions of vesicles as observed on the micrometer scale. PMID:20575588
Rotationally Vibrating Electric-Field Mill
Kirkham, Harold
2008-01-01
A proposed instrument for measuring a static electric field would be based partly on a conventional rotating-split-cylinder or rotating-split-sphere electric-field mill. However, the design of the proposed instrument would overcome the difficulty, encountered in conventional rotational field mills, of transferring measurement signals and power via either electrical or fiber-optic rotary couplings that must be aligned and installed in conjunction with rotary bearings. Instead of being made to rotate in one direction at a steady speed as in a conventional rotational field mill, a split-cylinder or split-sphere electrode assembly in the proposed instrument would be set into rotational vibration like that of a metronome. The rotational vibration, synchronized with appropriate rapid electronic switching of electrical connections between electric-current-measuring circuitry and the split-cylinder or split-sphere electrodes, would result in an electrical measurement effect equivalent to that of a conventional rotational field mill. A version of the proposed instrument is described.
Electric field measurements from Halley, Antarctica
Nicoll, Keri; Harrison, R. Giles
2016-04-01
Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.
Stratospheric electric field measurements with transmediterranean balloons
de La Morena, B. A.; Alberca, L. F.; Curto, J. J.; Holzworth, R. H.
1993-01-01
The horizontal component of the stratospheric electric field was measured using a balloon in the ODISEA Campaign of Transmediterranean Balloon Program. The balloon flew between Trapani (Sicily) and El Arenosillo (Huelva, Spain) along the 39 deg N parallel at a height between 34 and 24 km. The high values found for the field on fair-weather and its quasi-turbulent variation, both in amplitude and direction, are difficult to explain with the classical electric field source. A new source, first described by Holzworth (1989), is considered as possibly causing them.
Schwinger effect in inhomogeneous electric fields
Hebenstreit, Florian
2011-01-01
The vacuum of quantum electrodynamics is unstable against the formation of many-body states in the presence of an external electric field, manifesting itself as the creation of electron-positron pairs (Schwinger effect). This effect has been a long-standing but still unobserved prediction as the generation of the required field strengths has not been feasible so far. However, due to the advent of a new generation of high-intensity laser systems such as the European XFEL or the Extreme Light Infrastructure (ELI), this effect might eventually become observable within the next decades. Based on the equal-time Wigner formalism, various aspects of the Schwinger effect in electric fields showing both temporal and spatial variations are investigated. Regarding the Schwinger effect in time-dependent electric fields, analytic expressions for the equal-time Wigner function in the presence of a static as well as a pulsed electric field are derived. Moreover, the pair creation process in the presence of a pulsed electric...
Sintering of Ceramic Materials Under Electric Field
Naik , Kiran Suresh
2014-01-01
The remarkable discovery of flash sintering came across during the early work of Cologna et al. and emerged as an attractive technique in the field of ceramic processing. In this technique the applied electric field initiates the “flash” event, while the densification is controlled by the current density set. Sintering occurs in less than 5 s at a threshold temperature for a given applied field. The objective of this thesis is to analyse the phenomena of flash sintering with different cer...
Possible mechanism of electrical field origin around celestial bodies
Bisnovatyi-Kogan, G. S.
2002-01-01
Slow magnetic field variations in stars and planets create a quasistationary electrical field which may be observed. It is supposed that the electrical field near the Earth surface may be partially connected with variation of the Earth magnetic field. Two examples of the electrical field distribution around the infinite cylinder, and the circular loop with a lineary growing with time electrical currents are given.
Microwave electric field sensing with Rydberg atoms
Stack, Daniel T.; Kunz, Paul D.; Meyer, David H.; Solmeyer, Neal
2016-05-01
Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.
Schwinger Pair Production in Pulsed Electric Fields
Kim, Sang Pyo; Ruffini, Remo
2012-01-01
We numerically investigate the temporal behavior and the structure of longitudinal momentum spectrum and the field polarity effect on pair production in pulsed electric fields in scalar quantum electrodynamics (QED). Using the evolution operator expressed in terms of the particle and antiparticle operators, we find the exact quantum states under the influence of electric pulses and measure the number of pairs of the Minkowski particle and antiparticle. The number of pairs, depending on the configuration of electric pulses, exhibits rich structures in the longitudinal momentum spectrum and undergoes diverse dynamical behaviors at the onset of the interaction but always either converges to a momentum-dependent constant or oscillates around a momentum-dependent time average after the completion of fields.
Electric field induced deformation of sessile drops
Corson, Lindsey; Tsakonas, Costas; Duffy, Brian; Mottram, Nigel; Brown, Carl; Wilson, Stephen
2014-11-01
The ability to control the shape of a drop with the application of an electric field has been exploited for many technological applications including measuring surface tension, producing an optical display device, and optimising the optical properties of microlenses. In this work we consider, both theoretically and experimentally, the deformation of pinned sessile drops with contact angles close to either 0° or 90° resting on the lower substrate inside a parallel plate capacitor due to an A.C. electric field. Using both asymptotic and numerical approaches we obtain predictive equations for the static and dynamic drop shape deformations as functions of the key experimental parameters (drop size, capacitor plate separation, electric field magnitude and contact angle). The asymptotic results agree well with the experimental results for a range of liquids. We gratefully acknowledge the financial support of EPSRC via research Grants EP/J009865 and EP/J009873.
Electric field controlled emulsion phase contactor
Scott, Timothy C.
1995-01-01
A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.
Quasi-Static Electric Field Generator
Generazio, Edward R. (Inventor)
2017-01-01
A generator for producing an electric field for with an inspection technology system is provided. The generator provides the required variable magnitude quasi-static electric fields for the "illumination" of objects, areas and volumes to be inspected by the system, and produces human-safe electric fields that are only visible to the system. The generator includes a casing, a driven, non-conducting and triboelectrically neutral rotation shaft mounted therein, an ungrounded electrostatic dipole element which works in the quasi-static range, and a non-conducting support for mounting the dipole element to the shaft. The dipole element has a wireless motor system and a charging system which are wholly contained within the dipole element and the support that uses an electrostatic approach to charge the dipole element.
Electric-field-stimulated protein mechanics.
Hekstra, Doeke R; White, K Ian; Socolich, Michael A; Henning, Robert W; Šrajer, Vukica; Ranganathan, Rama
2016-12-15
The internal mechanics of proteins-the coordinated motions of amino acids and the pattern of forces constraining these motions-connects protein structure to function. Here we describe a new method combining the application of strong electric field pulses to protein crystals with time-resolved X-ray crystallography to observe conformational changes in spatial and temporal detail. Using a human PDZ domain (LNX2(PDZ2)) as a model system, we show that protein crystals tolerate electric field pulses strong enough to drive concerted motions on the sub-microsecond timescale. The induced motions are subtle, involve diverse physical mechanisms, and occur throughout the protein structure. The global pattern of electric-field-induced motions is consistent with both local and allosteric conformational changes naturally induced by ligand binding, including at conserved functional sites in the PDZ domain family. This work lays the foundation for comprehensive experimental study of the mechanical basis of protein function.
Microfluidic Screening of Electric Fields for Electroporation
Garcia, Paulo A.; Ge, Zhifei; Moran, Jeffrey L.; Buie, Cullen R.
2016-02-01
Electroporation is commonly used to deliver molecules such as drugs, proteins, and/or DNA into cells, but the mechanism remains poorly understood. In this work a rapid microfluidic assay was developed to determine the critical electric field threshold required for inducing bacterial electroporation. The microfluidic device was designed to have a bilaterally converging channel to amplify the electric field to magnitudes sufficient to induce electroporation. The bacterial cells are introduced into the channel in the presence of SYTOX®, which fluorescently labels cells with compromised membranes. Upon delivery of an electric pulse, the cells fluoresce due to transmembrane influx of SYTOX® after disruption of the cell membranes. We calculate the critical electric field by capturing the location within the channel of the increase in fluorescence intensity after electroporation. Bacterial strains with industrial and therapeutic relevance such as Escherichia coli BL21 (3.65 ± 0.09 kV/cm), Corynebacterium glutamicum (5.20 ± 0.20 kV/cm), and Mycobacterium smegmatis (5.56 ± 0.08 kV/cm) have been successfully characterized. Determining the critical electric field for electroporation facilitates the development of electroporation protocols that minimize Joule heating and maximize cell viability. This assay will ultimately enable the genetic transformation of bacteria and archaea considered intractable and difficult-to-transfect, while facilitating fundamental genetic studies on numerous diverse microbes.
Tellgren, E I; Teale, A M; Furness, J W; Lange, K K; Ekström, U; Helgaker, T
2014-01-21
We present a novel implementation of Kohn-Sham density-functional theory utilizing London atomic orbitals as basis functions. External magnetic fields are treated non-perturbatively, which enable the study of both magnetic response properties and the effects of strong fields, using either standard density functionals or current-density functionals-the implementation is the first fully self-consistent implementation of the latter for molecules. Pilot applications are presented for the finite-field calculation of molecular magnetizabilities, hypermagnetizabilities, and nuclear magnetic resonance shielding constants, focusing on the impact of current-density functionals on the accuracy of the results. Existing current-density functionals based on the gauge-invariant vorticity are tested and found to be sensitive to numerical details of their implementation. Furthermore, when appropriately regularized, the resulting magnetic properties show no improvement over standard density-functional results. An advantage of the present implementation is the ability to apply density-functional theory to molecules in very strong magnetic fields, where the perturbative approach breaks down. Comparison with high accuracy full-configuration-interaction results show that the inadequacies of current-density approximations are exacerbated with increasing magnetic field strength. Standard density-functionals remain well behaved but fail to deliver high accuracy. The need for improved current-dependent density-functionals, and how they may be tested using the presented implementation, is discussed in light of our findings.
Energy Technology Data Exchange (ETDEWEB)
Tellgren, E. I., E-mail: erik.tellgren@kjemi.uio.no; Lange, K. K.; Ekström, U.; Helgaker, T. [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); Teale, A. M., E-mail: andrew.teale@nottingham.ac.uk [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Furness, J. W. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)
2014-01-21
We present a novel implementation of Kohn–Sham density-functional theory utilizing London atomic orbitals as basis functions. External magnetic fields are treated non-perturbatively, which enable the study of both magnetic response properties and the effects of strong fields, using either standard density functionals or current-density functionals—the implementation is the first fully self-consistent implementation of the latter for molecules. Pilot applications are presented for the finite-field calculation of molecular magnetizabilities, hypermagnetizabilities, and nuclear magnetic resonance shielding constants, focusing on the impact of current-density functionals on the accuracy of the results. Existing current-density functionals based on the gauge-invariant vorticity are tested and found to be sensitive to numerical details of their implementation. Furthermore, when appropriately regularized, the resulting magnetic properties show no improvement over standard density-functional results. An advantage of the present implementation is the ability to apply density-functional theory to molecules in very strong magnetic fields, where the perturbative approach breaks down. Comparison with high accuracy full-configuration-interaction results show that the inadequacies of current-density approximations are exacerbated with increasing magnetic field strength. Standard density-functionals remain well behaved but fail to deliver high accuracy. The need for improved current-dependent density-functionals, and how they may be tested using the presented implementation, is discussed in light of our findings.
The convection electric field in auroral substorms
DEFF Research Database (Denmark)
Gjerløv, Jesper Wittendorff; Hoffman, R.A.
2001-01-01
Dynamics Explorer 2 (DE 2) electric field and ion drift data are used in a statistical study of the ionospheric convection electric field in bulge-type auroral substorms. Thirty-one individual DE 2 substorm crossings were carefully selected and organized by the use of global auroral images obtained...... by DE 1. The selected passes, which occurred during substorm expansion phase, maximum, or early recovery phase, cover the entire nighttime substorm. The organization of the data used the method developed by Fujii et al. [1994], which divided the data into six local time sectors covering the nighttime...
Electric Field Quantitative Measurement System and Method
Generazio, Edward R. (Inventor)
2016-01-01
A method and system are provided for making a quantitative measurement of an electric field. A plurality of antennas separated from one another by known distances are arrayed in a region that extends in at least one dimension. A voltage difference between at least one selected pair of antennas is measured. Each voltage difference is divided by the known distance associated with the selected pair of antennas corresponding thereto to generate a resulting quantity. The plurality of resulting quantities defined over the region quantitatively describe an electric field therein.
Building a non-perturbative quark-gluon vertex from a perturbative one
Bermudez, Rocio
2016-10-01
The quark-gluon vertex describes the electromagnetic and the strong interaction among these particles. The description of this interaction at high precision in both regimes, perturbative and non-perturbative, continues being a matter of interest in the context of QCD and Hadron Physics. There exist very helpful models in the literature that explain perturbative aspects of the theory but they fail describing non-perturbative phenomena, as confinement and dynamic chiral symmetry breaking. In this work we study the structure of the quark-gluon vertex in a non-perturbative regime examining QCD, checking results with QED, and working in the Schwinger-Dyson formalism.
Electric Field Effects in RUS Measurements
Energy Technology Data Exchange (ETDEWEB)
Darling, Timothy W [Los Alamos National Laboratory; Ten Cate, James A [Los Alamos National Laboratory; Allured, Bradley [UNIV NEVADA, RENO; Carpenter, Michael A [CAMBRIDGE UNIV. UK
2009-09-21
Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.
Electric field stimulated growth of Zn whiskers
Energy Technology Data Exchange (ETDEWEB)
Niraula, D.; McCulloch, J.; Irving, R.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Warrell, G. R.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)
2016-07-15
We have investigated the impact of strong (∼10{sup 4} V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.
Electric field stimulated growth of Zn whiskers
Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana
2016-07-01
We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.
Electric fields and double layers in plasmas
Singh, Nagendra; Thiemann, H.; Schunk, R. W.
1987-05-01
Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamical features of the double layers are discussed. These features, as seen in simulations, laboratory experiments, and theory, indicate that double layers and the currents through them undergo slow oscillations which are determined by the ion transit time across an effective length of the system in which double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations were considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields and double layers in an expanding plasma is discussed.
Non-perturbative gravity at different length scales
Energy Technology Data Exchange (ETDEWEB)
Folkerts, Sarah
2013-12-18
problem. Since the axion is the (pseudo-) Goldstone boson of a broken U(1) global symmetry, quantum gravitational global symmetry violations could reinstate the CP problem even in the presence of the axion. We show that in the presence of massless neutrinos possible conflicts with the axion solution can be resolved. Demanding a viable axion solution of the strong CP problem, we derive new bounds on neutrino masses. In addition, we investigate the QCD vacuum energy screening mechanism for light quarks. It is well-known that the θ-dependence of the QCD vacuum vanishes linearly with the lightest quark mass. By an analogy with Schwinger pair creation in a strong electric field, we consider vacuum screening by η' bubble nucleation. We find that using the standard instanton approximation for the η' potential, the linear dependence is not recovered. We take this as an indication for the non-analyticity of the QCD vacuum energy proposed by Witten. In the last part of this thesis, we are concerned with gravitational effects on cosmological scales. The recent Planck data indicate that one of the best motivated dark matter candidates, the axion, is in conflict with bounds on isocurvature perturbations. We show that the isocurvature fluctuations can be efficiently suppressed when introducing a non-minimal kinetic coupling for the axion field during inflation. Thus, the axion can be a viable dark matter candidate for a large range of parameters. We show that the same coupling allows for the Standard Model Higgs to drive inflation and the dark matter density to be produced by the axion. Gravitational effects on large scales would also be sensitive to a possible mass for the graviton. However, such a modification has been known to be plagued by inconsistencies. In light of the recent proposal of a ghost-free theory of massive gravity by de Rham, Gabadadze and Tolley, we investigate the cubic order interactions of this theory in terms of helicities of a massive spin-2
Critical electric field strengths of onion tissues treated by pulsed electric fields.
Asavasanti, Suvaluk; Ersus, Seda; Ristenpart, William; Stroeve, Pieter; Barrett, Diane M
2010-09-01
The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (E(c)) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-μs pulses indicate that breakdown of the plasma membrane occurs above E(c)= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either E(c)= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n≥10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses.
Multilayer graphene under vertical electric field
Kumar, S. Bala; GUO, Jing
2011-01-01
We study the effect of vertical electric field (E-field) on the electronic properties of multilayer graphene. We show that the effective mass, electron velocity and density-of-state of a bilayer graphene are modified under the E-field. We also study the transformation of the band structure of multilayer graphenes. E-field induces finite (zero) bandgap in the even (odd)-layer ABA-stacking graphene. On the other hand, finite bandgap is induced in all ABC-stacking graphene. We also identify the ...
Particle creation by peak electric field
Adorno, T C; Gitman, D M
2016-01-01
The particle creation by the so-called peak electric field is considered. The latter field is a combination of two exponential parts, one exponentially-increasing and another exponentially-decreasing. We find exact solutions of the Dirac equation with the field under consideration with appropriate asymptotic conditions and calculate all the characteristics of particle creation effect, in particular, differential mean numbers of created particle, total number of created particles, and the probability for a vacuum to remain a vacuum. Characteristic asymptotic regimes are discussed in detail and a comparison with the pure asymptotically decaying field is considered.
Particle creation by peak electric field
Energy Technology Data Exchange (ETDEWEB)
Adorno, T.C. [Tomsk State University, Department of Physics, Tomsk (Russian Federation); Gavrilov, S.P. [Tomsk State University, Department of Physics, Tomsk (Russian Federation); Herzen State Pedagogical University of Russia, Department of General and Experimental Physics, St. Petersburg (Russian Federation); Gitman, D.M. [Tomsk State University, Department of Physics, Tomsk (Russian Federation); P. N. Lebedev Physical Institute, Moscow (Russian Federation); University of Sao Paulo, Institute of Physics, CP 66318, Sao Paulo, SP (Brazil)
2016-08-15
The particle creation by the so-called peak electric field is considered. The latter field is a combination of two exponential parts, one exponentially increasing and another exponentially decreasing. We find exact solutions of the Dirac equation with the field under consideration with appropriate asymptotic conditions and calculate all the characteristics of particle creation effect, in particular, differential mean numbers of created particle, total number of created particles, and the probability for a vacuum to remain a vacuum. Characteristic asymptotic regimes are discussed in detail and a comparison with the pure asymptotically decaying field is considered. (orig.)
Health of workers exposed to electric fields
Energy Technology Data Exchange (ETDEWEB)
Broadbent, D.E.; Broadbent, M.H.; Male, J.C.; Jones, M.R.
1985-02-01
The results of health questionnaire interviews with 390 electrical power transmission and distribution workers, together with long term estimates of their exposure to 50 Hz electric fields, and short term measurements of the actual exposure for 287 of them are reported. Twenty eight workers received measurable exposures, averaging about 30 kVm-1h over the two week measurement period. Estimated exposure rates were considerably greater, but showed fair correlation with the measurements. Although the general level of health was higher than we have found in manual workers in other industries, there were significant differences in the health measures between different categories of job, different parts of the country, and in association with factors such as overtime, working alone, or frequently changing shift. After allowing for the effects of job and location, however, we found no significant correlations of health with either measured or estimated exposure to electric fields.
Leidenfrost droplets in an electric field
Wildeman, Sander; Sun, Chao; Lohse, Detlef
2014-11-01
In a recent video broadcast dubbed the ``Knitting Needle Experiment,'' astronaut Don Petit aboard the ISS demonstrated how weightless water droplets can be made to orbit a statically charged Teflon rod. We study the earthly analogue of mobile droplets in an electric field, whereby the mobility is ensured by a thin vapor film sustained between the droplet and a hot plate (the Leidenfrost effect). We find that in a strong vertical electric field the droplet starts to bounce progressively higher, defying gravitational attraction. From its trajectory we can deduce the temporal evolution of the charge on the droplet. The measurements show that the charge starts high and then decreases in a step-like manner as the droplet evaporates. The discharge trend is predicted well by treating the droplet as a dielectric sphere in electrical contact with the hot plate, but the mechanism by which definite lumps of charge are transferred through the vapor film is still an open question.
Pulsed Electric Field treatment of packaged food
Roodenburg, B.
2011-01-01
Food manufacturers are looking for new preservation techniques that don’t influence the fresh-like characteristics of products. Non-thermal pasteurisation of food with Pulsed Electric Fields (often referred to as PEF) is an emerging technology, where the change of the food is less than with thermal
Workshop on Biophysics of Transmembrane Electric Fields
1990-11-15
research on the ionic mechanisms of electric-field detection. To obtain detailed information on the electroreceptive membrane and its ionic channels...not to all cells, tissues, and organs of the human body. The electroreceptive membranes also provide a unique opportunity for com- paring the ionic
Modelling electricity forward markets by ambit fields
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole; Fred Espen Benth, Fred Espen; Veraart, Almut
This paper proposes a new modelling framework for electricity forward markets, which is based on ambit fields. The new model can capture many of the stylised facts observed in energy markets. One of the main differences to the traditional models lies in the fact that we do not model the dynamics...
Motional Spin Relaxation in Large Electric Fields
Schmid, Riccardo; Filippone, B W
2008-01-01
We discuss the precession of spin-polarized Ultra Cold Neutrons (UCN) and $^{3}\\mathrm{He}$ atoms in uniform and static magnetic and electric fields and calculate the spin relaxation effects from motional $v\\times E$ magnetic fields. Particle motion in an electric field creates a motional $v\\times E$ magnetic field, which when combined with collisions, produces variations of the total magnetic field and results in spin relaxation of neutron and $^{3}\\mathrm{He}$ samples. The spin relaxation times $T_{1}$ (longitudinal) and $T_{2}$ (transverse) of spin-polarized UCN and $^{3}\\mathrm{He}$ atoms are important considerations in a new search for the neutron Electric Dipole Moment at the SNS \\emph{nEDM} experiment. We use a Monte Carlo approach to simulate the relaxation of spins due to the motional $v\\times E$ field for UCN and for $^{3}\\mathrm{He}$ atoms at temperatures below $600 \\mathrm{mK}$. We find the relaxation times for the neutron due to the $v\\times E$ effect to be long compared to the neutron lifetime, ...
Hashimoto, Koji
2013-01-01
We analyze vacuum instability of strongly coupled gauge theories in a constant electric field using AdS/CFT correspondence. The model is the N=2 1-flavor supersymmetric large N_c QCD in the strong 't Hooft coupling limit. We calculate the Euler-Heisenberg effective Lagrangian L(E), which encodes the nonlinear response and the quantum decay rate of the vacuum in a background electric field E, from the complex D-brane action in AdS/CFT. We find that the decay rate given by Im L(E) becomes nonzero above a critical electric field set by the confining force between quarks. A large-E expansion of Im L(E) is found to coincide with that of the Schwinger effects in QED, replacing its electron mass by the confining force. Then, the time-dependent response of the system in a strong electric field is solved non-perturbatively, and we observe a universal thermalization at a shortest timescale "Planckian thermalization time" t ~ 1/T ~ E^{-1/2}. Here, T is an effective temperature which quarks feel in the nonequilibrium sta...
Renormalization Constants of Quark Operators for the Non-Perturbatively Improved Wilson Action
Becirevic, D; Lubicz, V; Martinelli, G; Papinutto, Mauro; Reyes, J
2004-01-01
We present the results of an extensive lattice calculation of the renormalization constants of bilinear and four-quark operators for the non-perturbatively O(a)-improved Wilson action. The results are obtained in the quenched approximation at four values of the lattice coupling by using the non-perturbative RI/MOM renormalization method. Several sources of systematic uncertainties, including discretization errors and final volume effects, are examined. The contribution of the Goldstone pole, which in some cases may affect the extrapolation of the renormalization constants to the chiral limit, is non-perturbatively subtracted. The scale independent renormalization constants of bilinear quark operators have been also computed by using the lattice chiral Ward identities approach and compared with those obtained with the RI-MOM method. For those renormalization constants the non-perturbative estimates of which have been already presented in the literature we find an agreement which is typically at the level of 1%...
Propagation of Gluons From a Non-Perturbative Evolution Equation in Axial Gauges
Kinder-Geiger, Klaus
1999-01-01
We derive a non-perturbative evolution equation for the gluon propagator in axial gauges based on the framework of Wetterich's formulation of the exact renormalization group. We obtain asymptotic solutions to this equation in the ultraviolet and infrared limits.
Preliminary Studies on Pulsed Electric Field Breakdown of Lead Azide
1976-10-01
1/2 OS CO ton NO. S3L TECHNICAL REPORT 4991 PRELIMINARY SUJDfES ON PULSED ELECTRIC FIELD BREAKDOWN OF LEAD AZIDE L AVRAMI M. BUMS D. DOWNS...Introduction Background A. Contact Effects B. Pulsed Electric Field Measurements Experimental A. Contact Effects B. Pulsed Electric Fields Discussion...B. Pulsed Electric Field Measurements The application of pulsed electric fields to lead azide does not exactly simulate the conditions experienced
Complex curves and non-perturbative effects in c=1 string theory
Alexandrov, S
2004-01-01
We investigate a complex curve in the $c=1$ string theory which provides a geometric interpretation for different kinds of D-branes. The curve is constructed for a theory perturbed by a tachyon potential using its matrix model formulation. The perturbation removes the degeneracy of the non-perturbed curve and allows to identify its singularities with ZZ branes. Also, using the constructed curve, we find non-perturbative corrections to the free energy and elucidate their CFT origin.
Tikekar superdense stars in electric fields
Komathiraj, K.; Maharaj, S. D.
2007-04-01
We present exact solutions to the Einstein-Maxwell system of equations with a specified form of the electric field intensity by assuming that the hypersurface {t=constant} are spheroidal. The solution of the Einstein-Maxwell system is reduced to a recurrence relation with variable rational coefficients which can be solved in general using mathematical induction. New classes of solutions of linearly independent functions are obtained by restricting the spheroidal parameter K and the electric field intensity parameter α. Consequently, it is possible to find exact solutions in terms of elementary functions, namely, polynomials and algebraic functions. Our result contains models found previously including the superdense Tikekar neutron star model [J. Math. Phys. 31, 2454 (1990)] when K=-7 and α=0. Our class of charged spheroidal models generalize the uncharged isotropic Maharaj and Leach solutions [J. Math. Phys. 37, 430 (1996)]. In particular, we find an explicit relationship directly relating the spheroidal parameter K to the electromagnetic field.
Check of a new non-perturbative mechanism for elementary fermion mass generation
Capitani, Stefano; Dimopoulos, Petros; Frezzotti, Roberto; Garofalo, M; Knippschild, Bastian; Kostrzewa, Bartosz; Ottnad, Konstantin; Rossi, Giancarlo; Schrröck, Mario; Urbach, Carsten
2016-01-01
We consider a field theoretical model where a SU(2) fermion doublet, subjected to non-Abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an irrelevant Wilson-like term. Despite the presence of these two chiral breaking operators in the Lagrangian, an exact symmetry acting on fermions and scalars prevents perturbative mass corrections. In the phase where fermions are massless (Wigner phase) the Yukawa coupling can be tuned to a critical value at which chiral transformations acting on fermions only become a symmetry of the theory (up to cutoff effects). In the Nambu-Goldstone phase of the critical theory a fermion mass term of dynamical origin is expected to arise in the Ward identities of the purely fermionic chiral transformations. Such a non-perturbative mechanism of dynamical mass generation can provide a "natural" (\\`a la 't Hooft) alternative to the Higgs mechanism adopted in the Standard Model. Here we lay down the theoretical framework necessary to demonstrate...
Enhancement of Higgs to diphoton decay width in non-perturbative Higgs model
Energy Technology Data Exchange (ETDEWEB)
Haba, Naoyuki [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kaneta, Kunio [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Mimura, Yukihiro [Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC (China); Takahashi, Ryo, E-mail: ryo.takahasi88@gmail.com [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)
2013-01-29
We investigate a possibility if a loop diagram via Higgsino can enhance the Higgs to diphoton decay width in supersymmetric models with an extension of Higgs sector. A model with an additional non-renormalizable term of Higgs fields is firstly analyzed where the higher order term can introduce the Higgs coupling to Higgsinos as well as charged Higgs bosons. We point out that a choice of the Higgs coupling to obtain a significant size of enhancement of diphoton decay width reduces the Higgs mass and/or a size of non-renormalizable term needs to be large and a cutoff scale is around the weak scale. Another model in which the Higgsino mass term is generated by a non-perturbative instanton effect via a strong dynamics in a context of SUSY QCD is also suggested. It is shown that the sign of the Higgs coupling to fermions is opposite from perturbative models due to an operator including bosonic fields in the denominator and a constructive contribution to the diphoton decay amplitude can be easily obtained in this kind of model.
Conically shaped drops in electric fields
Stone, Howard A.; Brenner, Michael P.; Lister, John R.
1996-11-01
When an electric field is applied to a dielectric liquid containing a suspended immiscible fluid drop, the drop deforms into a prolate ellipsoidal shape. Above a critical field strength the drop develops conical ends, as first observed by Zeleny [Phys. Rev. 10, 1 (1917)] and Wilson & Taylor [Proc. Camb. Phil. Soc. 22, 728 (1925)] for, respectively, the case of conducting drops and soap films in air. The case of two dielectric liquids was studied recently using a slender drop approximation by Li, Halsey & Lobkovsky [Europhys. Lett 27, 575 (1994)]. In this presentation we further develop the slender body approximation to obtain coupled ordinary differential equations for the electric field and the drop shape. Analytical formulae are derived which approximately give the cone angle as a function of the dielectric constant ratio between the two fluids, and the minimum applied electric field at which conical tips first form as a function of the dielectric constant ratio. Finally, drops shapes are calculated numerically and compared with the common prolate shape assumption.
Electric Field and Humidity Trigger Contact Electrification
Directory of Open Access Journals (Sweden)
Yanzhen Zhang
2015-01-01
Full Text Available Here, we study the old problem of why identical insulators can charge one another on contact. We perform several experiments showing that, if driven by a preexisting electric field, charge is transferred between contacting insulators. This transfer happens because the insulator surfaces adsorb small amounts of water from a humid atmosphere. We believe the electric field then separates positively from negatively charged ions prevailing within the water, which we believe to be hydronium and hydroxide ions, such that at the point of contact, positive ions of one insulator neutralize negative ions of the other one, charging both of them. This mechanism can explain for the first time the observation made four decades ago that wind-blown sand discharges in sparks if and only if a thunderstorm is nearby.
Broadband Electric-Field Sensor Array Technology
2012-08-05
the RF DUT. The RF receiver measures the power output from the photodiode, Prf. Fringing RF electric fields from a microstrip resonator circuit ...are measured by placing the ring resonators on top of the circuit . A photograph of the microstrip resonator circuit is shown in Fig. 6(b). The... circuit is a one port device and consists of a 50 Ω input line gap-coupled to a second 50 Ω microstrip line resonator. From vector network analyzer (VNA
Electrohydrodynamic deformation of capsules in electric field
Das, Sudip; Thaokar, Rochish
2016-11-01
Micron size capsules are abundant in natural, technological and biological processes but they still require extensive investigation for better understanding of their mechanical behavior. A spherical capusle containing a Newtonian fluid bounded by a viscoelastic membrane and immersed in another Newtonian fluid, and subject to electric field is considered. Discontinuity of electrical properties such as conductivity and permittivity leads to a net Maxwell stress at the capsule interface. In response the capsule undergoes elastic deformation, leading to strain fields and elastic stresses that can balance the applied forces. We investigate this problem with fully resolved hydrodynamics in the Stokes flow limit and electrostatics using the capacitance model. Effect of AC, DC and pulsed DC fields is investigated. Our results show that membrane electrical properties have a huge impact on the equilibrium deformation as well as on the break up of capsules. Our results match with the literature results in the limit of high conductance of the membrane. Analytical theory is employed using spherical harmonics and numerical investigations are conducted using the Boundary integral method.
Flame spread over inclined electrical wires with AC electric fields
Lim, Seung J.
2017-07-21
Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field applied, the flame spread rate and the flame width of downwardly spreading flames (DSFs) decreased from the horizontal case for −20° ≤ θ < 0° and maintained near constant values for −90° ≤ θ < −20°, while the flame spread rate increased appreciably as the inclination angle of upwardly spreading flames (USFs) increased. When an AC electric field was applied, the behavior of flame spread rate in DSFs (USFs) could be classified into two (three) sub-regimes characterized by various functional dependences on VAC, fAC, and θ. In nearly all cases of DSFs, a globular molten polyethylene formed ahead of the spreading flame edge, occasionally dripping onto the ground. In these cases, an effective flame spread rate was defined to represent the burning rate by measuring the mass loss due to dripping. This effective spread rate was independent of AC frequency, while it decreased linearly with voltage and was independent of the inclination angle. In DSFs, when excessively high voltage and frequency were applied, the dripping led to flame extinction during propagation and the extinction frequency correlated well with applied voltage. In USFs, when high voltage and frequency were applied, multiple globular molten PEs formed at several locations, leading to ejections of multiple small flame segments from the main flame, thereby reducing the flame spread rate, which could be attributed to the electrospray phenomenon.
Non-perturbative measurement of low-intensity charged particle beams
Fernandes, M.; Geithner, R.; Golm, J.; Neubert, R.; Schwickert, M.; Stöhlker, T.; Tan, J.; Welsch, C. P.
2017-01-01
Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of 30 {nA}.
Non-perturbative over-production of axion-like-particles (ALPs) via derivative interaction
Mazumdar, Anupam
2015-01-01
Axion like particles (ALPs) are quite generic in many scenarios for physics beyond the Standard Model, they are pseudoscalar Nambu-Goldstone bosons, and appear once any global $U(1)$ symmetry is broken spontaneously. The ALPs can gain mass from various non-perturbative quantum effects, such as anomalies or instantons. ALPs can couple to the matter sector incluidng a scalar condensate such as inflaton or moduli field via derivative interactions, which are suppressed by the axion {\\it decay constant}, $f_\\chi$ . Although weakly interacting, the ALPs can be produced abundantly from the coherent oscillations of a homogeneous condensate. In this paper we will study such a scenario where the ALPs can be produced abundantly, and in some cases can even overclose the Universe via odd and even dimensional operators, as long as $f_\\chi/\\Phi_{\\rm I} \\ll 1$, where $\\Phi_{\\rm I}$ denotes the initial amplitude of the coherent oscillations of the scalar condensate, $\\phi$. We will briefly mention how such dangerous overprodu...
Conformal bootstrap: non-perturbative QFT's under siege
CERN. Geneva
2016-01-01
[Exceptionally in Council Chamber] Originally formulated in the 70's, the conformal bootstrap is the ambitious idea that one can use internal consistency conditions to carve out, and eventually solve, the space of conformal field theories. In this talk I will review recent developments in the field which have boosted this program to a new level. I will present a method to extract quantitative informations in strongly-interacting theories, such as 3D Ising, O(N) vector model and even systems without a Lagrangian formulation. I will explain how these techniques have led to the world record determination of several critical exponents. Finally, I will review exact analytical results obtained using bootstrap techniques.
Electrical Grounding - a Field for Geophysicists and Electrical Engineers Partnership
Freire, P. F.; Pane, E.; Guaraldo, N.
2012-12-01
, layered stratified or showing lateral variations, ranging down to several tens of kilometers deep, reaching the crust-mantle interface (typically with the order of 30-40 km). This work aims to analyze the constraints of the current soil models being used for grounding electrodes design, and suggests the need of a soil modeling methodology compatible with large grounding systems. Concerning the aspects related to soil modeling, electrical engineers need to get aware of geophysics resources, such as: - geophysical techniques for soil electrical resistivity prospection (down to about 15 kilometers deep); and - techniques for converting field measured data, from many different geophysical techniques, into adequate soil models for grounding grid simulation. It is also important to equalize the basic knowledge for the professionals that are working together for the specific purpose of soil modeling for electrical grounding studies. The authors have experienced the situation of electrical engineers working with geophysicists, but it was not clear for the latter the effective need of the electrical engineers, and for the engineers it was unknown the available geophysical resources, and also, what to do convert the large amount of soil resistivity data into a reliable soil model.
Black hole entropy from non-perturbative gauge theory
Kabat, D; Lowe, D A; Kabat, Daniel; Lifschytz, Gilad; Lowe, David A.
2001-01-01
We present the details of a mean-field approximation scheme for the quantum mechanics of N D0-branes at finite temperature. The approximation can be applied at strong 't Hooft coupling. We find that the resulting entropy is in good agreement with the Bekenstein-Hawking entropy of a ten-dimensional non-extremal black hole with 0-brane charge. This result is in accord with the duality conjectured by Itzhaki, Maldacena, Sonnenschein and Yankielowicz. We discuss ways of resolving the black hole horizon, and also study the spectrum of single-string excitations within the quantum mechanics.
Energy Technology Data Exchange (ETDEWEB)
Timoshkin, I V [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); MacGregor, S J [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Fouracre, R A [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Crichton, B H [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Anderson, J G [Robertson Trust Laboratory for Electronic Sterilization Technologies (ROLEST), Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom)
2006-02-07
The pulsed electric field (PEF) treatment of liquid and pumpable products contaminated with microorganisms has attracted significant interest from the pulsed power and bioscience research communities particularly because the inactivation mechanism is non-thermal, thereby allowing retention of the original nutritional and flavour characteristics of the product. Although the biological effects of PEF have been studied for several decades, the physical mechanisms of the interaction of the fields with microorganisms is still not fully understood. The present work is a study of the dynamics of the electrical field both in a PEF treatment chamber with dielectric barriers and in the plasma (cell) membrane of a microbial cell. It is shown that the transient process can be divided into three physical phases, and models for these phases are proposed and briefly discussed. The complete dynamics of the time development of the electric field in a spherical dielectric shell representing the cellular membrane is then obtained using an analytical solution of the Ohmic conduction problem. It was found that the field in the membrane reaches a maximum value that could be two orders of magnitude higher than the original Laplacian electrical field in the chamber, and this value was attained in a time comparable to the field relaxation time in the chamber. Thus, the optimal duration of the field during PEF treatment should be equal to such a time.
Electric Field Induced Surface Modification of Au
Energy Technology Data Exchange (ETDEWEB)
Erchak, A.A.; Franklin, G.F.; Houston, J.E.; Mayer, T.M.; Michalske, T.A.
1999-02-15
We discuss the role of localized high electric fields in the modification of Au surfaces with a W probe using the Interfacial Force Microscope. Upon bringing a probe close to a Au surface, we measure both the interfacial force and the field emission current as a function of separation with a constant potential of 100 V between tip and sample. The current initially increases exponentially as the separation decreases. However, at a distance of less than {approximately} 500{angstrom} the current rises sharply as the surface begins to distort and rapidly close the gap. Retraction of the tip before contact is made reveals the formation of a mound on the surface. We propose a simple model, in which the localized high electric field under the tip assists the production of mobile Au adatoms by detachment from surface steps, and a radial field gradient causes a net flux of atoms toward the tip by surface diffusion. These processes give rise to an unstable surface deformation which, if left unchecked, results in a destructive mechanical contact. We discuss our findings with respect to earlier work using voltage pulses in the STM as a means of nanofabrication.
Biofouling prevention with pulsed electric fields
Energy Technology Data Exchange (ETDEWEB)
Abou-Ghazala, A.; Schoenbach, K.H.
2000-02-01
Temporary immobilization of aquatic nuisance species through application of short electric pulses has been explored as a method to prevent biofouling in cooling water systems where untreated lake, river, or sea water is used. In laboratory experiments, electrical pulses with amplitudes on the order of kilovolts/centimeter and submicrosecond duration were found to be most effective in stunning time in a temporal range from minutes to hours. The temporary immobilization is assumed to be caused by reversible membrane breakdown. This assumption is supported by results of measurements of the energy required for stunning. Based on the data obtained in laboratory experiments, field experiments in a tidal water environment have been performed. The flow velocity was such that the residence time of the aquatic nuisance species in the system was approximately half a minute. The results showed that the pulsed electric field method provides full protection against biofouling when pulses of 0.77 {micro}s width and 6 kV/cm amplitude are applied to the water at the inlet of such a cooling water system. Even at amplitudes of 1 kV/cm, the protection is still in the 90% range, at an energy expenditure of 1 kWh for the treatment of 60,000 gallons of water.
Spontaneous electric fields in solid films: spontelectrics
DEFF Research Database (Denmark)
Field, David; Plekan, Oksana; Cassidy, Andrew
2013-01-01
When dipolar gases are condensed at sufficiently low temperature onto a solid surface, they form films that may spontaneously exhibit electric fields in excess of 108V/m. This effect, called the ‘spontelectric effect’, was recently revealed using an instrument designed to measure scattering...... that the spontelectric field generally decreases monotonically with increased deposition temperature, with the exception of methyl formate that shows an increase beyond a critical range of deposition temperature. Films of spontelectric material show a Curie temperature above which the spontelectric effect disappears....... Heterolayers may also be laid down creating potential wells on the nanoscale. A model is put forward based upon competition between dipole alignment and thermal disorder, which is successful in reproducing the variation of the degree of dipole alignment and the spontelectric field with deposition temperature...
Can Neural Activity Propagate by Endogenous Electrical Field?
National Research Council Canada - National Science Library
Qiu, Chen; Shivacharan, Rajat S; Zhang, Mingming; Durand, Dominique M
2015-01-01
.... The only explanation left is an electrical field effect. We tested the hypothesis that endogenous electric fields are sufficient to explain the propagation with in silico and in vitro experiments...
Electropumping of water with rotating electric fields
DEFF Research Database (Denmark)
Hansen, Jesper Schmidt; De Luca, Sergio; Todd, Billy
2013-01-01
of the fluid. By selectively tuning the degree of hydrophobicity of the solid walls one can generate a net unidirectional flow. Our results for the linear streaming and angular velocities of the confined water are in general agreement with the extended hydrodynamical theory for this process, though also...... require some sort of direct intrusion into the nanofluidic system, and involve mechanical or electronic components. In this paper, we present the first nonequilibrium molecular dynamics results to demonstrate that non-intrusive electropumping of liquid water on the nanoscale can be performed by subtly...... exploiting the coupling of spin angular momentum to linear streaming momentum. A spatially uniform rotating electric field is applied to water molecules, which couples to their permanent electric dipole moments. The resulting molecular rotational momentum is converted into linear streaming momentum...
Characterization of composite particles responsive to electric and magnetic fields
Institute of Scientific and Technical Information of China (English)
ZHAO Xiaopeng; GUO Hongxia
2004-01-01
The multilayer particles with responses to electric and magnetic fields are a prerequisite for particles assembled under external fields. Three routes to produce particles responsive to electric and magnetic fields are presented in this article. The size and morphology, properties as well as the electric-magnetic responses of three kinds of particles are comparatively discussed. This will provide a useful basis for the control of the behavior of the particles in suspensions by external electric and magnetic fields.
Non-perturbative renormalization of static-light four-fermion operators in quenched lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Palombi, F. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Papinutto, M.; Pena, C. [CERN, Geneva (Switzerland). Physics Dept., Theory Div.; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik
2007-06-15
We perform a non-perturbative study of the scale-dependent renormalization factors of a multiplicatively renormalizable basis of {delta}B=2 parity-odd four-fermion operators in quenched lattice QCD. Heavy quarks are treated in the static approximation with various lattice discretizations of the static action. Light quarks are described by nonperturbatively O(a) improved Wilson-type fermions. The renormalization group running is computed for a family of Schroedinger functional (SF) schemes through finite volume techniques in the continuum limit. We compute non-perturbatively the relation between the renormalization group invariant operators and their counterparts renormalized in the SF at a low energy scale. Furthermore, we provide non-perturbative estimates for the matching between the lattice regularized theory and all the SF schemes considered. (orig.)
A New Approach to Analytic, Non-Perturbative and Gauge-Invariant QCD
Fried, H M; Sheu, Y -M
2012-01-01
Following a previous calculation of quark scattering in eikonal approximation, this paper presents a new, analytic and rigorous approach to the calculation of QCD phenomena. In this formulation a basic distinction between the conventional "idealistic" description of QCD and a more "realistic" description is brought into focus by a non-perturbative, gauge-invariant evaluation of the Schwinger solution for the QCD generating functional in terms of the exact Fradkin representations of the Green's functional and the vacuum functional. Because quarks exist asymptotically only in bound states, their transverse coordinates can never be measured with arbitrary precision; the non-perturbative neglect of this statement leads to obstructions that are easily corrected by invoking in the basic Lagrangian a probability amplitude which describes such transverse imprecision. The second result of this non-perturbative analysis is the appearance of a new and simplifying output called "Effective Locality", in which the interact...
More on the non-perturbative Gribov-Zwanziger quantization of linear covariant gauges
Capri, M A L; Fiorentini, D; Guimaraes, M S; Justo, I F; Mintz, B W; Palhares, L F; Pereira, A D; Sobreiro, R F; Sorella, S P
2015-01-01
In this paper, we discuss the gluon propagator in the linear covariant gauges in $D=2,3,4$ Euclidean dimensions. Non-perturbative effects are taken into account via the so-called Refined Gribov-Zwanziger framework. We point out that, as in the Landau and maximal Abelian gauges, for $D=3,4$, the gluon propagator displays a massive (decoupling) behaviour, while for $D=2$, a scaling one emerges. All results are discussed in a setup that respects the Becchi-Rouet-Stora-Tyutin (BRST) symmetry, through a recently introduced non-perturbative BRST transformation. We also propose a minimizing functional that could be used to construct a lattice version of our non-perturbative definition of the linear covariant gauge.
Pire, B
2009-01-01
QCD is the theory of strong interactions and non-perturbative methods have been developed to address the confinement property of QCD. Many experimental measurements probe the confining dynamics, and it is well-known that hard scattering processes allow the extraction of non perturbative hadronic matrix elements. To study exclusive hard processes, such as electromagnetic form factors and reactions like gamma* N -> gamma N', gamma* N -> pi N', gamma* gamma -> pi pi, antiproton proton ->gamma* pi in particular kinematics (named as generalized Bjorken regime), one introduces specific non-perturbative objects, namely generalized parton distributions (GPDs), distribution amplitudes (DA) and transition distribution amplitudes (TDA), which are Fourier transformed non-diagonal matrix elements of non-local operators on the light-cone. We review here a selected sample of exclusive amplitudes in which the quark and gluon content of hadrons is probed, and emphasize that much remains to be done to successfully compute thei...
Non-perturbative gluon-hadron inputs for all available forms of QCD factorization
Ermolaev, B I
2016-01-01
Description of hadronic reactions at high energies is conventionally done on basis of QCD factoriza- tion so that factorization convolutions involve non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct the inputs for the gluon- hadron scattering amplitudes in the forward kinematics and, using the Optical theorem, convert them into inputs for gluon distributions in the both polarized and unpolarized hadrons. Firstly, we derive general mathematical criteria which any model for the inputs should obey and then suggest a Resonance Model satisfying those criteria. This model is inspired by a simple observation: after emitting an active parton off the hadron, the remaining ensemble of spectators becomes unstable and therefore it can be described through factors of the resonance type. Exploiting Resonance Model, we obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available forms of QCD factorization...
Collider searches for non-perturbative low-scale gravity states
Gingrich, Douglas M
2015-01-01
The possibility of producing non-perturbative low-scale gravity states in collider experiments was first discussed in about 1998. The ATLAS and CMS experiments have searched for non-perturbative low-scale gravity states using the Large Hadron Collider (LHC) with a proton--proton centre of mass energy of 8 TeV. These experiments have now seriously confronted the possibility of producing non-perturbative low-scale gravity states which were proposed over 17 years ago. I will summarise the results of the searches, give a personal view of what they mean, and make some predictions for 13 TeV centre of mass energy. I will also discuss early ATLAS 13 TeV centre of mass energy results.
Hydrogel Actuation by Electric Field Driven Effects
Morales, Daniel Humphrey
Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of
Electric field control of Skyrmions in magnetic nanodisks
Nakatani, Y.; Hayashi, M.; Kanai, S.; Fukami, S.; Ohno, H.
2016-04-01
The control of magnetic Skyrmions confined in a nanometer scale disk using electric field pulses is studied by micromagnetic simulation. A stable Skyrmion can be created and annihilated by an electric field pulse depending on the polarity of the electric field. Moreover, the core direction of the Skyrmion can be switched using the same electric field pulses. Such creation and annihilation of Skyrmions, and its core switching do not require any magnetic field and precise control of the pulse length. This unconventional manipulation of magnetic texture using electric field pulses allows a robust way of controlling magnetic Skyrmions in nanodiscs, a path toward building ultralow power memory devices.
Radial-Electric-Field Piezoelectric Diaphragm Pumps
Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma
2009-01-01
In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.
Electrostatic air filters generated by electric fields
Energy Technology Data Exchange (ETDEWEB)
Bergman, W.; Biermann, A.H.; Hebard, H.D.; Lum, B.Y.; Kuhl, W.D.
1981-01-27
This paper presents theoretical and experimental findings on fibrous filters converted to electrostatic operation by a nonionizing electric field. Compared to a conventional fibrous filter, the electrostatic filter has a higher efficiency and a longer, useful life. The increased efficiency is attributed to a time independent attraction between polarized fibers and charged, polarized particles and a time dependent attraction between charged fibers and charged, polarized particles. The charge on the fibers results from a dynamic process of charge accumulation due to the particle deposits and a charge dissipation due to the fiber conductivity.
Plasma instabilities in high electric fields
DEFF Research Database (Denmark)
Morawetz, K.; Jauho, Antti-Pekka
1994-01-01
We analyze nonequilibrium screening with nonequilibrium Green function techniques. By employing the generalized Kadanoff-Baym ansatz to relate the correlation function to the nonequilibrium distribution function, the latter of which is assumed to be a shifted Maxwellian, an analytically tractable...... expression is derived for the nonequilibrium dielectric function epsilon(K, omega). For certain values of momenta K and frequency omega, Imepsilon(K, omega) becomes negative, implying a plasma instability. This new instability exists only for strong electric fields, underlining its nonequilibrium origin....
Resonance model for non-perturbative inputs to gluon distributions in the hadrons
Ermolaev, B I; Troyan, S I
2015-01-01
We construct non-perturbative inputs for the elastic gluon-hadron scattering amplitudes in the forward kinematic region for both polarized and non-polarized hadrons. We use the optical theorem to relate invariant scattering amplitudes to the gluon distributions in the hadrons. By analyzing the structure of the UV and IR divergences, we can determine theoretical conditions on the non-perturbative inputs, and use these to construct the results in a generalized Basic Factorization framework using a simple Resonance Model. These results can then be related to the K_T and Collinear Factorization expressions, and the corresponding constrains can be extracted.
Controlling quark mass determinations non-perturbatively in three-flavour QCD
Directory of Open Access Journals (Sweden)
Campos Isabel
2017-01-01
Full Text Available The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS¯$\\overline {{\\rm{MS}}} $ scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf = 3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.
Scalar coupling evolution in a non-perturbative QCD resummation scheme
Energy Technology Data Exchange (ETDEWEB)
Gomez, J.D., E-mail: jgomez@ufabc.edu.br [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-170, Santo André, SP (Brazil); Natale, A.A., E-mail: natale@ift.unesp.br [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-170, Santo André, SP (Brazil); Instituto de Física Teórica, UNESP, Rua Dr. Bento T. Ferraz, 271, Bloco II, 01140-070, São Paulo, SP (Brazil)
2015-07-30
We compute the Standard Model scalar coupling (λ) evolution in a particular QCD resummation scheme, where the QCD coupling becomes infrared finite due to the presence of a dynamically generated gluon mass, leading to the existence of a non-perturbative infrared fixed point. We discuss how this scheme can be fixed taking recourse to phenomenological considerations in the infrared region. The QCD β function associated to this non-perturbative coupling when introduced into the SM renormalization group equations increases the λ values at high energies.
Controlling quark mass determinations non-perturbatively in three-flavour QCD
Campos, Isabel; Pena, Carlos; Preti, David; Ramos, Alberto; Vladikas, Anastassios
2016-01-01
The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.
Rizzo, Antonio; Ruud, Kenneth; Helgaker, Trygve; Jaszuński, Michał
1998-08-01
The electric field gradient (EFG) at the nuclei, the generalized Sternheimer shielding constants and the EFG electric dipole polarizabilities are computed for eight small molecules employing multiconfigurational self-consistent field wave functions and the corresponding linear and quadratic response functions. The molecules studied are H2, N2, CO, HF, C2H2, HCl, HCN, and HNC, all of which are linear. For the hydrogen molecule, full configuration-interaction results for the properties are also reported. The dependence of the computed quantities on the basis set and the electron-correlation treatment is analyzed.
Dielectric Fluid in Inhomogeneous Pulsed Electric Field
Shneider, M N
2013-01-01
We consider the dynamics of a compressible fluid under the influence of electrostrictive ponderomotive forces in strong inhomogeneous nonstationary electric fields. It is shown that if the fronts of the voltage rise at a sharp, needle-like electrode are rather steep (less than or about nanoseconds), and the region of negative pressure arises, which can reach values at which the fluid loses its continuity with the formation of cavitation ruptures. If the voltage on the electrode is not large enough or the front is flatter, the cavitation in the liquid does not occur. However, a sudden shutdown of the field results in a reverse flow of liquid from the electrode, which leads to appearance of negative pressure, and, possibly, cavitation.
ELECTRIC FIELD SENSORS BASED ON MEMS TECHNOLOGY
Institute of Scientific and Technical Information of China (English)
Gong Chao; Xia Shanhong; Deng Kai; Bai Qiang; Chen Shaofeng
2005-01-01
The design and optimization of two types of novel miniature vibrating Electric Field Sensors (EFSs) based on Micro Electro Mechanical Systems (MEMS) technology are presented.They have different structures and vibrating modes. The volume is much smaller than other types of charge-induced EFSs such as field-mills. As miniaturizing, the induced signal is reduced enormously and a high sensitive circuit is needed to detect it. Elaborately designed electrodes can increase the amplitude of the output current, making the detecting circuit simplified and improving the signal-to-noise ratio. Computer simulations for different structural parameters of the EFSs and vibrating methods have been carried out by Finite Element Method (FEM). It is proved that the new structures are realizable and the output signals are detectable.
Nonlinear relaxation field in charged systems under high electric fields
Energy Technology Data Exchange (ETDEWEB)
Morawetz, K
2000-07-01
The influence of an external electric field on the current in charged systems is investigated. The results from the classical hierarchy of density matrices are compared with the results from the quantum kinetic theory. The kinetic theory yields a systematic treatment of the nonlinear current beyond linear response. To this end the dynamically screened and field-dependent Lenard-Balescu equation is integrated analytically and the nonlinear relaxation field is calculated. The classical linear response result known as Debye - On-Sager relaxation effect is only obtained if asymmetric screening is assumed. Considering the kinetic equation of one specie the other species have to be screened dynamically while the screening with the same specie itself has to be performed statically. Different other approximations are discussed and compared. (author)
Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors
Institute of Scientific and Technical Information of China (English)
SUN Bao; CHEN Fu-Shen
2009-01-01
We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive im-pulse electric field measurement. The integrated optical sensor is based on a Mach-Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The max-imal detectable electric field range (-75 kV/m to 245 kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation.
Inhibition of brain tumor cell proliferation by alternating electric fields
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [School of Biosystem and Biomedical Science, Korea University, Seoul 136-703 (Korea, Republic of); Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul 136-703 (Korea, Republic of); Koh, Eui Kwan [Seoul Center, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of)
2014-11-17
This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields.
Saturation of the Electric Field Transmitted to the Magnetosphere
Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.
2010-01-01
We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.
Dynamics of an electric dipole moment in a stochastic electric field.
Band, Y B
2013-08-01
The mean-field dynamics of an electric dipole moment in a deterministic and a fluctuating electric field is solved to obtain the average over fluctuations of the dipole moment and the angular momentum as a function of time for a Gaussian white-noise stochastic electric field. The components of the average electric dipole moment and the average angular momentum along the deterministic electric-field direction do not decay to zero, despite fluctuations in all three components of the electric field. This is in contrast to the decay of the average over fluctuations of a magnetic moment in a stochastic magnetic field with Gaussian white noise in all three components. The components of the average electric dipole moment and the average angular momentum perpendicular to the deterministic electric-field direction oscillate with time but decay to zero, and their variance grows with time.
Manipulating colloids with charges and electric fields
Leunissen, M. E.
2007-02-01
This thesis presents the results of experimental investigations on a variety of colloidal suspensions. Colloidal particles are at least a hundred times larger than atoms or molecules, but suspended in a liquid they display the same phase behavior, including fluid and crystalline phases. Due to their relatively large size, colloids are much easier to investigate and manipulate, though. This makes them excellent condensed matter model systems. With this in mind, we studied micrometer-sized perspex (‘PMMA’) spheres, labeled with a fluorescent dye for high-resolution confocal microscopy imaging, and suspended in a low-polar mixture of the organic solvents cyclohexyl bromide and cis-decalin. This system offered us the flexibility to change the interactions between the particles from ‘hard-sphere-like’ to long-ranged repulsive (between like-charged particles), long-ranged attractive (between oppositely charged particles) and dipolar (in an electric field). We investigated the phase behavior of our suspensions as a function of the particle concentration, the ionic strength of the solvent and the particles’ charges. In this way, we obtained new insight in the freezing and melting behavior of like-charged and oppositely charged colloids. Interestingly, we found that the latter can readily form large crystals, thus defying the common belief that plus-minus interactions inevitably lead to aggregation. Moreover, we demonstrated that these systems can serve as a reliable model system for classical ionic matter (‘salts’), and that opposite-charge interactions can greatly facilitate the self-assembly of new structures with special properties for applications. On a slightly different note, we also studied electrostatic effects in mixtures of the cyclohexyl bromide solvent and water, both with and without colloidal particles present. This provided new insight in the stabilization mechanisms of oil-water emulsions and gave us control over the self-assembly of various
Electrical integrity of oxides in a radiation field
Energy Technology Data Exchange (ETDEWEB)
Zinkle, S.J. [Oak Ridge National Laboratory, TN (United States); Kinoshita, C.
1996-04-01
In the absence of an applied electric field, irradiation generally produces a decrease in the permanent (beam-off) electrical conductivity of ceramic insulators. However, in the past 6 years several research groups have reported a phenomenon known as radiation induced electrical degradation (RIED), which produces significant permanent increases in the electrical conductivity of ceramic insulators irradiated with an applied electric field. RIED has been reported to occur at temperatures between 420 and 800 K with applied electric fields as low as 20 V/mm.
Physical consequences of black holes in non-perturbative quantum gravity and inflationary cosmology
Reska, P.M.
2011-01-01
In this thesis the consequences of the presence of a Schwarzschild black hole in de Sitter space are studied in the setting of non-perturbative quantum gravity and in inflationary cosmology. We first review the formalism of Causal Dynamical Triangulations (CDT) which implements a lattice regularizat
Spectral zeta function and non-perturbative effects in ABJM Fermi-gas
Hatsuda, Yasuyuki
2015-11-01
The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of "non-perturbative" poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example associated with a spectral problem in topological string theory. A conjectured non-perturbative free energy on the resolved conifold is successfully reproduced in this framework.
Constraining the Higgs boson mass: A non-perturbative lattice study
Jansen, Karl; Nagy, Attila
2012-01-01
We present non-perturbatively obtained results for upper and lower Higgs boson mass bounds using a chiral invariant lattice formulation of the Higgs-Yukawa sector of the standard model. We determine the mass bounds both, for a standard model top quark mass and for a possible fourth quark generation with masses up to 700GeV.
Non-perturbative Heavy Quark Effective Theory: An application to semi-leptonic B-decays
Della Morte, Michele; Simma, Hubert; Sommer, Rainer
2015-01-01
We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays at the leading order in 1/m_h.
Puhr, M
2016-01-01
We use exactly chiral overlap lattice fermions to investigate the Chiral Separation Effect in quenched QCD at finite density. We employ a recently developed numerical method which allows, for the first time, to address the transport properties of exactly chiral lattice fermions with non-zero chemical potential. Studying the axial current along the external magnetic field, we find a linear dependence consistent with the free fermion result for topologically trivial gauge field configurations. However, for configurations with nontrivial topology in the confinement regime the axial current is strongly suppressed due to contributions of topological modes of the Dirac operator, which suggests that non-perturbative corrections to the Chiral Separation Effect have topological origin.
Electric field enhancement of depolarization of excited states
Energy Technology Data Exchange (ETDEWEB)
Nayfeh, M.H.; Hillard, G.B.; Glab, W.L.
1985-12-01
Our calculations show that an external dc electric field can enhance by many orders of magnitude the depolarization cross section of highly excited atoms by charged particles. The enhancement is due to the fact that the electric field extends and shifts the electronic charge distribution along its direction, thus effectively creating a giant electric dipole in the atom.
Liquid methanol under a static electric field
Energy Technology Data Exchange (ETDEWEB)
Cassone, Giuseppe, E-mail: giuseppe.cassone@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France); Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Giaquinta, Paolo V., E-mail: paolo.giaquinta@unime.it [Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); Saija, Franz, E-mail: saija@ipcf.cnr.it [CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Saitta, A. Marco, E-mail: marco.saitta@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France)
2015-02-07
We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.
Patchy particle packing under electric fields.
Song, Pengcheng; Wang, Yufeng; Wang, Yu; Hollingsworth, Andrew D; Weck, Marcus; Pine, David J; Ward, Michael D
2015-03-01
Colloidal particles equipped with two, three, or four negatively charged patches, which endow the particles with 2-fold, 3-fold, or tetrahedral symmetries, form 1D chains, 2D layers, and 3D packings when polarized by an AC electric field. Two-patch particles, with two patches on opposite sides of the particle (2-fold symmetry) pack into the cmm plane group and 3D packings with I4mm space group symmetry, in contrast to uncharged spherical or ellipsoidal colloids that typically crystallize into a face-centered ABC layer packing. Three-patch particles (3-fold symmetry) form chains having a 21 screw axis symmetry, but these chains pair in a manner such that each individual chain has one-fold symmetry but the pair has 21 screw axis symmetry, in an arrangement that aligns the patches that would favor Coulombic interactions along the chain. Surprisingly, some chain pairs form unanticipated double-helix regions that result from mutual twisting of the chains about each other, illustrating a kind of polymorphism that may be associated with nucleation from short chain pairs. Larger 2D domains of the three-patch particles crystallize in the p6m plane group with alignment (with respect to the field) and packing densities that suggest random disorder in the domains, whereas four-patch particles form 2D domains in which close-packed rows are aligned with the field.
Review Of Fiber-Optic Electric-Field Sensors
De Paula, Ramon P.; Jarzynski, Jacek
1989-01-01
Tutorial paper reviews state of art in fiber-optic sensors of alternating electric fields. Because such sensors are made entirely of dielectric materials, they are relatively transparent to incident electric fields; they do not distort fields significantly. Paper presents equations that express relationships among stress, strain, and electric field in piezoactive plastic and equations for phase shift in terms of photoelastic coefficients and strains in optical fiber.
The influence of electric field and confinement on cell motility.
Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C
2013-01-01
The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.
Biological effects of electric fields: an overview
Energy Technology Data Exchange (ETDEWEB)
Anderson, L.E.; Phillips, R.D.
1983-11-01
An overview of the literature suggests tha electric-field exposure is an environmental agent/influence of relatively low potential toxicity to biological systems. Generally, many of the biological effects which have been reported are quite subtle and differences between exposed and unexposed subjects may be masked by normal biological variations. However, several recent reports indicate possibly more serious consequences from chronic exposure, emphasizing the need for more research in epidemiology and laboratory experiments. This paper presents a cursory overview of investigations on the biological consequences of exposure to ELF electromagnetic fields. Three important topics are discussed, including: 1) the general methodology of exposure experiments, including those elements which are critical for definitive studies in biological systems; 2) a brief discussion of epidemiological and clinical studies conducted to date; and 3) a somewhat more extensive examination of animal experiments representing major areas of investigation (behavior, biological rhythms, nervous and endocrine systems, bone growth and repair, cardiovascular system and blood chemistry, immunology, reproduction, growth and development mortality and pathology, cellular and membrane studies, and mutagenesis). A discussion of current concepts, possible mechanisms and future directions of research is presented. 110 references.
Iversen, I. B.; Madsen, M. M.; Dangelo, N.
1985-01-01
Measurements of the atmospheric (vertical) electric field with balloons in the stratosphere are reported. The atmospheric electrical conductivity is also measured and the current density inferred. The average vertical current shows the expected variation with universal time and is also seen to be influenced by external (magnetospheric) electric fields.
Non-perturbative renormalisation of Delta F=2 four-fermion operators in two-flavour QCD
Dimopoulos, P; Palombi, Filippo; Papinutto, Mauro; Peña, C; Vladikas, A; Wittig, H
2008-01-01
Using Schroedinger Functional methods, we compute the non-perturbative renormalisation and renormalisation group running of several four-fermion operators, in the framework of lattice simulations with two dynamical Wilson quarks. Two classes of operators have been targeted: (i) those with left-left current structure and four propagating quark fields/ (ii) all operators containing two static quarks. In both cases, only the parity-odd contributions have been considered, being the ones that renormalise multiplicatively. Our results, once combined with future simulations of the corresponding lattice hadronic matrix elements, may be used for the computation of phenomenological quantities of interest, such as B_K and B_B (the latter also in the static limit).
Non-perturbative renormalisation of {delta}F=2 four-fermion operators in two-flavour QCD
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, P.; Vladikas, A. [INFN, Sezione di Roma II (Italy)]|[Rome-3 Univ. (Italy). Dipt. di Fisica; Herdoiza, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Palombi, F.; Papinutto, M. [CERN, Geneva (Switzerland). Physics Dept., TH Division; Pena, C. [Universidad Autonoma de Madrid (Spain). Dept. de Fisica Teorica C-XI]|[Univ. Autonoma de Madrid (Spain). Inst. de Fisica Teorica UAM/CSIC C-XVI; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik
2007-12-15
Using Schroedinger Functional methods, we compute the non-perturbative renormalisation and renormalisation group running of several four-fermion operators, in the framework of lattice simulations with two dynamical Wilson quarks. Two classes of operators have been targeted: (i) those with left-left current structure and four propagating quark fields; (ii) all operators containing two static quarks. In both cases, only the parity-odd contributions have been considered, being the ones that renormalise multiplicatively. Our results, once combined with future simulations of the corresponding lattice hadronic matrix elements, may be used for the computation of phenomenological quantities of interest, such as B{sub K} and B{sub B} (the latter also in the static limit). (orig.)
Buchert, Thomas
2012-01-01
In this first paper we present a Lagrangian framework for the description of structure formation in general relativity, restricting attention to irrotational dust matter. As an application we present a self-contained derivation of a general-relativistic analogue of Zel'dovich's approximation for the description of structure formation in cosmology, and compare it with previous suggestions in the literature. This approximation is then investigated: paraphrasing the derivation in the Newtonian framework we provide general-relativistic analogues of the basic system of equations for a single dynamical field variable and recall the first-order perturbation solution of these equations. We then define a general-relativistic analogue of Zel'dovich's approximation and investigate consequences by functionally evaluating relevant variables. We so obtain a possibly powerful model that, although constructed through extrapolation of a perturbative solution, can be used to address non-perturbatively, e.g. problems of structu...
Field-Induced Superconductivity in Electric Double Layer Transistors
Ueno, Kazunori; Shimotani, Hidekazu; Yuan, Hongtao; Ye, Jianting; Kawasaki, Masashi; Iwasa, Yoshihiro
2014-01-01
Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, electric-field-induced superconductivity was believed to be possi
PHASE GRADIENT METHOD OF MAGNETIC FIELD MEASUREMENTS IN ELECTRIC VEHICLES
Directory of Open Access Journals (Sweden)
N. G. Ptitsyna
2013-01-01
Full Text Available Operation of electric and hybrid vehicles demands real time magnetic field control, for instance, for fire and electromagnetic safety. The article deals with a method of magnetic field measurements onboard electric cars taking into account peculiar features of these fields. The method is based on differential methods of measurements, and minimizes the quantity of magnetic sensors.
Flow-driven cell migration under external electric fields
Li, Yizeng; Mori, Yoichiro; Sun, Sean X.
2016-01-01
Electric fields influence many aspects of cell physiology, including various forms of cell migration. Many cells are sensitive to electric fields, and can migrate toward a cathode or an anode, depending on the cell type. In this paper, we examine an actomyosin-independent mode of cell migration under electrical fields. Our theory considers a one-dimensional cell with water and ionic fluxes at the cell boundary. Water fluxes through the membrane are governed by the osmotic pressure difference across the cell membrane. Fluxes of cations and anions across the cell membrane are determined by the properties of the ion channels as well as the external electric field. Results show that without actin polymerization and myosin contraction, electric fields can also drive cell migration, even when the cell is not polarized. The direction of migration with respect to the electric field direction is influenced by the properties of ion channels, and are cell-type dependent. PMID:26765031
Generation of Electric Field and Net Charge in Hall Reconnection
Institute of Scientific and Technical Information of China (English)
MA Zhi-Wei; FENG Shu-Ling
2008-01-01
@@ Generation of Hall electric field and net charge associated with magnetic reconnection is studied under different initial conditions of plasma density and magnetic field. With inclusion of the Hall effects, decoupling of the electron and ion motions leads to the formation of a narrow layer with strong electric field and large net charge density along the separatrix. The asymmetry of the plasma density or magnetic field or both across the current sheet will largely increase the magnitude of the electric field and net charge. The results indicate that the asymmetry of the magnetic field is more effective in producing larger electric field and charge density. The electric field and net charge are always much larger in the low density or/and high magnetic field side than those in the high density or/and low magnetic field side. Both the electric field and net charge density are linearly dependent on the ratios of the plasma density or the square of the magnetic field across the current sheet. For the case with both initial asymmetries of the magnetic field and density, rather large Hall electric field and charge density are generated.
Electrically small, complementary electric-field-coupled resonator antennas
Odabasi, H.; Teixeira, F. L.; Guney, D. O.
2013-02-01
We study the radiation properties of electrically small resonant antennas (ka CELC) resonators and a monopole antenna. We use such parasitic ELC and CELC "metaresonators" to design various electrically small antennas. In particular, monopole-excited and bent-monopole-excited CELC resonator antennas are proposed that provide very low profiles on the order of λ0/20. We compare the performance of the proposed ELC and CELC antennas against more conventional designs based upon split-ring resonators.
Effective Action of Scalar QED in Electric Field Backgrounds
Kim, Sang Pyo; Yoon, Yongsung
2008-01-01
We use the evolution operator method to find the one-loop effective action of scalar QED in electric field backgrounds in terms of the Bogoliubov coefficient between the ingoing and the outgoing vacuum. The effective action shows the general relation between the vacuum persistence and the mean number of created pairs for any electric field. We obtain the exact effective action for a constant electric field and a pulsed electric field, E_0 sech^2 (t/tau), and show that the imaginary part correctly yields the vacuum persistence.
Linear electric field time-of-flight ion mass spectrometer
Funsten, Herbert O.; Feldman, William C.
2008-06-10
A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.
Electric field effects on electronic characteristics of arsenene nanoribbons
Luo, Yanwei; Li, Yuxiao; Wang, Fei; Guo, Peng; Jia, Yu
2017-10-01
By using the first-principles calculations, we investigate the effects of electric field on electronic structures of armchair and zigzag arsenene nanoribbons (AsNRs) with different widths. The results show that for each case, quantum size effects induce a smaller band gap in larger AsNRs. Moreover, electric field can reduce effectively the band gap of AsNRs. In addition, the electric field can induce only the transition of band structures in the A-AsNRs or Z-AsNRs with narrow size. The band gap decrease more rapidly and the threshold electric field induced metal becomes smaller in the wider AsNRs.
Effects of aging in electric field on 2024 alloy
Institute of Scientific and Technical Information of China (English)
王秀芳; 孙东立; 武高辉; 王美玲
2002-01-01
The effect of heat treatment in an electric field on micro-plastic deformation characteristics of 2024 Al alloy was investigated.The mechanism of aging in an electric field affecting the micro-plastic deformation behavior was preliminarily discussed.The results show that the resistance to micro-plastic deformation of the alloy can be greatly increased by aging in an electric field.Aging temperature,aging time and electric field strength are selected by adopting the orthogonal design method and the optimum technological parameters are obtained.
Effect of applied DC electric fields in flame spread over polyethylene-coated electrical wire
Jin, Young Kyu
2011-03-01
We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ±7 kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet. © 2011 The Korean Society of Mechanical Engineers.
Non-perturbative BRST quantization of Euclidean Yang-Mills theories in Curci-Ferrari gauges
Energy Technology Data Exchange (ETDEWEB)
Pereira, A.D. [UFF, Universidade Federal Fluminense, Instituto de Fisica, Campus da Praia Vermelha, Niteroi, RJ (Brazil); Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Potsdam (Germany); UERJ, Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro (Brazil); Sobreiro, R.F. [UFF, Universidade Federal Fluminense, Instituto de Fisica, Campus da Praia Vermelha, Niteroi, RJ (Brazil); Sorella, S.P. [UERJ, Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro (Brazil)
2016-10-15
In this paper we address the issue of the non-perturbative quantization of Euclidean Yang-Mills theories in the Curci-Ferrari gauge. In particular, we construct a refined Gribov-Zwanziger action for this gauge, which takes into account the presence of gauge copies as well as the dynamical formation of dimension-two condensates. This action enjoys a non-perturbative BRST symmetry recently proposed in Capri et al. (Phys. Rev. D 92(4), 045039. doi:10.1103/PhysRevD.92.045039. arXiv:1506.06995 [hepth], 2015). Finally, we pay attention to the gluon propagator in different space-time dimensions. (orig.)
Factorization and infrared properties of non-perturbative contributions to DIS structure functions
Ermolaev, B I; Troyan, S I
2010-01-01
Analytical expressions for the non-perturbative components of the hadronic scattering amplitudes and the DIS structure functions are not usually obtained from theoretical considerations, but are introduced phenomenologically by fitting the data. We derive some restrictions for such contributions from the general concepts of factorization and integrability. These restrictions are obtained in the context of both k_T and collinear factorizations. We also show that the use of the collinear factorization basically makes the DIS structure functions be dependent on the factorization scale. Our analysis shows that singular factors of the type x^{-a} in the initial parton densities can be used for the singlet component of the structure function F_1, provided a <1, but excludes the use of them for the other structure functions. The restrictions for the non-perturbative contributions we obtain can also be applied to other QCD reactions at high energies.
Non-perturbative Contributions from Complexified Solutions in $\\mathbb{C}P^{N-1}$ Models
Fujimori, Toshiaki; Misumi, Tatsuhiro; Nitta, Muneto; Sakai, Norisuke
2016-01-01
We discuss the non-perturbative contributions from real and complex saddle point solutions in the $\\mathbb{C}P^1$ quantum mechanics with fermionic degrees of freedom, using the Lefschetz thimble formalism beyond the gaussian approximation. We find bion solutions, which correspond to (complexified) instanton-antiinstanton configurations stabilized in the presence of the fermionic degrees of freedom. By computing the one-loop determinants in the bion backgrounds, we obtain the leading order contributions from both the real and complex bion solutions. To incorporate quasi zero modes which become nearly massless in a weak coupling limit, we regard the bion solutions as well-separated instanton-antiinstanton configurations and calculate a complexified quasi moduli integral based on the Lefschetz thimble formalism. The non-perturbative contributions from the real and complex bions are shown to cancel out in the supersymmetric case and give an (expected) ambiguity in the non-supersymmetric case, which plays a vital ...
Ab Initio Approach to the Non-Perturbative Scalar Yukawa Model
Li, Yang; Maris, P; Vary, J P
2015-01-01
We report on the first non-perturbative calculation of the quenched scalar Yukawa model in the four-body Fock sector truncation. The light-front Hamiltonian approach with a Fock sector dependent renormalization is applied. We study the Fock sector contribution and the electromagnetic form factor in the non-perturbative region. We find that the one- and two-body contributions dominate the Fock space up to coupling $\\alpha\\approx 1.7$. By comparing with lower Fock sector truncations, we show that the form factor converges with respect to the Fock sector expansion. As we approach the coupling $\\alpha \\approx 2.2$, we discover that the four-body contribution rises rapidly and overtakes the two- and three-body contributions.
Ab initio approach to the non-perturbative scalar Yukawa model
Directory of Open Access Journals (Sweden)
Yang Li
2015-09-01
Full Text Available We report on the first non-perturbative calculation of the scalar Yukawa model in the single-nucleon sector up to four-body Fock sector truncation (one “scalar nucleon” and three “scalar pions”. The light-front Hamiltonian approach with a systematic non-perturbative renormalization is applied. We study the n-body norms and the electromagnetic form factor. We find that the one- and two-body contributions dominate up to coupling α≈1.7. As we approach the coupling α≈2.2, we discover that the four-body contribution rises rapidly and overtakes the two- and three-body contributions. By comparing with lower sector truncations, we show that the form factor converges with respect to the Fock sector expansion.
Kostouki, Anna
2009-01-01
Applying a novel non-perturbative functional method framework to a two-dimensional bosonic sigma model with tachyon, dilaton and graviton backgrounds we construct exact (non perturbative in the Regge slope) inflationary solutions, consistent with world-sheet Weyl Invariance. The mechanism for inflation entails a (partial) "alignment" between tachyon and dilaton backgrounds in the solution space. Some cosmological solutions which contain inflationary eras for a short period and interpolate between flat universes in the far past and far future are also discussed. These solutions are characterized by the absence of cosmological horizons, and therefore have well-defined scattering amplitudes. This makes them compatible with a perturbative string framework, and therefore it is these solutions that we consider as self-consistent in our approach. Within the context of the interpolating solutions, string production at the end of inflation (preheating) may also be studied. The advantage of our method is that the solut...
HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation
Energy Technology Data Exchange (ETDEWEB)
Blossier, Benoit [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Edinburgh Univ. (United Kingdom). School of Physics and Astronomy - SUPA; Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2010-01-15
We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m{sub b}. Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m{sub b} in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)
Non-perturbative improvement of quark mass renormalization in two-flavour lattice QCD
Fritzsch, Patrick; Tantalo, Nazario
2010-01-01
We non-perturbatively determine the renormalization constant and the improvement coefficients relating the renormalized current and subtracted quark mass in O(a) improved two-flavour lattice QCD. We employ the Schr\\"odinger functional scheme and fix the physical extent of the box by working at a constant value of the renormalized coupling. Our calculation yields results which cover two regions of bare parameter space. One is the weak-coupling region suitable for volumes of about half a fermi. By making simulations in this region, quarks as heavy as the bottom can be propagated with the full relativistic QCD action and renormalization problems in HQET can be solved non-perturbatively by a matching to QCD in finite volume. The other region refers to the common parameter range in large-volume simulations of two-flavour lattice QCD, where our results have particular relevance for charm physics applications.
Non-perturbative renormalization of the quark condensate in Ginsparg-Wilson regularizations
Hernández, Pilar; Lellouch, L P; Wittig, H; Hernandez, Pilar; Jansen, Karl; Lellouch, Laurent; Wittig, Hartmut
2001-01-01
We present a method to compute non-perturbatively the renormalization constant of the scalar density for Ginsparg-Wilson fermions. It relies on chiral symmetry and is based on a matching of renormalization group invariant masses at fixed pseudoscalar meson mass, making use of results previously obtained by the ALPHA Collaboration for O(a)-improved Wilson fermions. Our approach is quite general and enables the renormalization of scalar and pseudoscalar densities in lattice regularizations that preserve chiral symmetry and of fermion masses in any regularization. As an application we compute the non-perturbative factor which relates the renormalization group invariant quark condensate to its bare counterpart, obtained with overlap fermions at beta=5.85 in the quenched approximation.
Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai
2011-01-01
The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...
Scattering polarization in the presence of magnetic and electric fields
Energy Technology Data Exchange (ETDEWEB)
Yee Oo, Yee [Department of Physics, Mandalay University, Mandalay (Myanmar); Sampoorna, M. [Indian Institute of Astrophysics, Bangalore 560 034 (India); Joint Astronomy Program, Department of Physics, IISc, Bangalore 560 012 (India); Nagendra, K.N. [Indian Institute of Astrophysics, Bangalore 560 034 (India); Ananthamurthy, Sharath [Department of Physics, Bangalore University, Bangalore 560 056 (India); Ramachandran, G. [Indian Institute of Astrophysics, Bangalore 560 034 (India)], E-mail: gr@iiap.res.in
2007-11-15
The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Limiting cases of scattering under Zeeman effect, and Hanle effect in weak magnetic fields are discussed. The theory is general enough to handle scattering in intermediate magnetic fields (Hanle-Zeeman effect) and for arbitrary orientation of magnetic field. The quadrupolar electric field produces asymmetric line shifts, and causes interesting level-crossing phenomena either in the absence of an ambient magnetic field, or in its presence. It is shown that the quadrupolar electric field produces an additional depolarization in the Q/I profiles and rotation of the plane of polarization in the U/I profile over and above that arising from magnetic field itself. This characteristic may have a diagnostic potential to detect steady-state and time-varying electric fields that surround radiating atoms in solar atmospheric layers.
Pulsed electric field assisted assembly of polyaniline
Kumar, Arun; Kazmer, David O.; Barry, Carol M. F.; Mead, Joey L.
2012-08-01
Assembling conducting polyaniline (PANi) on pre-patterned nano-structures by a high rate, commercially viable route offers an opportunity for manufacturing devices with nanoscale features. In this work we report for the first time the use of pulsed electric field to assist electrophoresis for the assembly of conducting polyaniline on gold nanowire interdigitated templates. This technique offers dynamic control over heat build-up, which has been a main drawback in the DC electrophoresis and AC dielectrophoresis as well as the main cause of nanowire template damage. The use of this technique allowed higher voltages to be applied, resulting in shorter assembly times (e.g., 17.4 s, assembly resolution of 100 nm). Moreover, the area coverage increases with the increase in number of pulses. A similar trend was observed with the deposition height and the increase in deposition height followed a linear trend with a correlation coefficient of 0.95. When the experimental mass deposited was compared with Hamaker’s theoretical model, the two were found to be very close. The pre-patterned templates with PANi deposition were subsequently used to transfer the nanoscale assembled PANi from the rigid templates to thermoplastic polyurethane using the thermoforming process.
Surface electric fields for North America during historical geomagnetic storms
Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.
2013-01-01
To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.
Further generalization of the Borel transform for the non-perturbative regime
Energy Technology Data Exchange (ETDEWEB)
Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Marucho, M. E-mail: afa@venus.fisica.unlp.edu.ar
2000-09-04
A new generalization of the Borel transform improving the Duncan-Pernice proposal, and designed for obtaining any non perturbative contributions is presented. This new transform leads to a non-ambiguous reconstruction of the original theory. This generalized transform is applied to the analysis of a one-dimensional spin chain and the two-dimensional non-linear sigma model on the lattice. In both models the singularity structure related to renormalons is obtained.
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, P.; Vladikas, A. [INFN, Sezione di Roma ' ' Tor Vegata' ' (Italy)]|[Universita die Roma ' ' Tor Vegata' ' (Italy). Dipt. die Fisica; Giusti, L.; Pena, C. [European Lab. for Particle Physics (CERN), Geneva (Switzerland); Hernandez, P. [Valencia Univ., Burjassot (Spain). Dpto. de Fisica Teorica and IFIC; Palombi, F.; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik; Wennekers, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2006-07-15
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the {delta}S=1 and {delta}S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays. (Orig.)
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Dimopoulos, P; Hernández, P; Palombi, Filippo; Peña, C; Vladikas, A; Wennekers, J; Wittig, H
2006-01-01
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the Delta S=1 and Delta S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, P. [INFN, Sezione di Rome ' Tor Vergata' , c/o Dipartimento di Fisica, Universita di Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Giusti, L. [CERN, Physics Department, TH Division, CH-1211 Geneva 23 (Switzerland); Hernandez, P. [Departamento de Fisica Teorica and IFIC, Universitat de Valencia, E-46100 Burjassot (Spain); Palombi, F. [Institut fuer Kernphysik, University of Mainz, D-55099 Mainz (Germany); Pena, C. [CERN, Physics Department, TH Division, CH-1211 Geneva 23 (Switzerland)]. E-mail: carlos.pena.ruano@cern.ch; Vladikas, A. [INFN, Sezione di Rome ' Tor Vergata' , c/o Dipartimento di Fisica, Universita di Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, I-00133 Rome (Italy); Wennekers, J. [DESY, Theory Group, Notkestrasse 85, D-22603 Hamburg (Germany); Wittig, H. [Institut fuer Kernphysik, University of Mainz, D-55099 Mainz (Germany)
2006-09-28
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the {delta}S=1 and {delta}S=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Comments on Exact Quantization Conditions and Non-Perturbative Topological Strings
Hatsuda, Yasuyuki
2015-01-01
We give some remarks on exact quantization conditions associated with quantized mirror curves of local Calabi-Yau threefolds, conjectured in arXiv:1410.3382. It is shown that they characterize a non-perturbative completion of the refined topological strings in the Nekrasov-Shatashvili limit. We find that the quantization conditions enjoy an exact S-dual invariance. We also discuss Borel summability of the semi-classical spectrum.
Non-perturbative renormalisation of left left four-fermion operators with Neuberger fermions
Dimopoulos, P.; Giusti, L.; Hernández, P.; Palombi, F.; Pena, C.; Vladikas, A.; Wennekers, J.; Wittig, H.
2006-09-01
We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the ΔS = 1 and ΔS = 2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays.
Factorization and infrared properties of non-perturbative contributions to DIS structure functions
Energy Technology Data Exchange (ETDEWEB)
Ermolaev, B.I. [Ioffe Physico-Technical Institute, St. Petersburg (Russian Federation); Greco, M. [University Roma Tre, Department of Physics (Italy); INFN, Rome (Italy); Troyan, S.I. [St. Petersburg Institute of Nuclear Physics, Gatchina (Russian Federation)
2011-09-15
In this paper we present a new derivation of QCD factorization. We deduce the k{sub T} and collinear factorizations for the DIS structure functions by consecutive reductions of a more general theoretical construction. We begin by studying the amplitude of forward Compton scattering off a hadron target, representing this amplitude as a set of convolutions of two blobs connected by the simplest, two-parton intermediate states. Each blob in the convolutions can contain both the perturbative and non-perturbative contributions. We formulate conditions for separating the perturbative and non-perturbative contributions and attributing them to the different blobs. After that the convolutions correspond to QCD factorization. Then we reduce this totally unintegrated (basic) factorization first to k{sub T} -factorization and finally to collinear factorization. In order to yield a finite expression for the Compton amplitude, the integration over the loop momentum in the basic factorization must be free of both ultraviolet and infrared singularities. This obvious mathematical requirement leads to theoretical restrictions on the non-perturbative contributions (parton distributions) to the Compton amplitude and the DIS structure functions related to the Compton amplitude through the Optical Theorem. In particular, our analysis excludes the use of the singular factors x{sup -a} (with a >0) in the fits for the quark and gluon distributions because such factors contradict the integrability of the basic convolutions for the Compton amplitude. This restriction is valid for all DIS structure functions in the framework of both k{sub T} -factorization and collinear factorization if we attribute the perturbative contributions only to the upper blob. The restrictions on the non-perturbative contributions obtained in the present paper can easily be extended to other QCD processes where the factorization is exploited. (orig.)
Non-integer Quantum Transition, a True Non-perturbation Effect in Laser-Atom Interaction
Institute of Scientific and Technical Information of China (English)
ZHANG Qi-Ren
2007-01-01
We show that in the quantum transition of an atom interacting with an intense laser of circular frequencyω, the energy difference between the initial and the final states of the atom is not necessarily an integer multiple of the quantum energy (h)ω. This kind of non-integer transition is a true non-perturbation effect in laser-atom interaction.
Non-perturbative effects for the Quark-Gluon Plasma equation of state
Energy Technology Data Exchange (ETDEWEB)
Begun, V. V., E-mail: viktor.begun@gmail.com; Gorenstein, M. I., E-mail: goren@bitp.kiev.ua; Mogilevsky, O. A. [Bogolyubov Institute for Theoretical Physics (Ukraine)
2012-07-15
The non-perturbative effects for the Quark-Gluon Plasma (QGP) equation of state (EoS) are considered. The modifications of the bag model EoS are constructed to satisfy the main qualitative features observed for the QGP EoS in the lattice QCD calculations. A quantitative comparison with the lattice results is done for the SU(3) gluon plasma and for the QGP with dynamical quarks. Our analysis advocates a negative value of the bag constant B.
Non-perturbative effects for the Quark-Gluon Plasma equation of state
Begun, V. V.; Gorenstein, M. I.; Mogilevsky, O. A.
2012-07-01
The non-perturbative effects for the Quark-Gluon Plasma (QGP) equation of state (EoS) are considered. The modifications of the bag model EoS are constructed to satisfy the main qualitative features observed for the QGP EoS in the lattice QCD calculations. A quantitative comparison with the lattice results is done for the SU(3) gluon plasma and for the QGP with dynamical quarks. Our analysis advocates a negative value of the bag constant B.
Non-perturbative QCD Effects and the Top Mass at the Tevatron
Wicke, Daniel
2008-01-01
The modelling of non-perturbative effects is an important part of modern collider physics simulations. In hadron collisions there is some indication that the modelling of the interactions of the beam remnants, the underlying event, may require non-trivial colour reconnection effects to be present. We recently introduced a universally applicable toy model of such reconnections, based on hadronising strings. This model, which has one free parameter, has been implemented in the Pythia event generator. We then considered several parameter sets (`tunes'), constrained by fits to Tevatron minimum-bias data, and determined the sensitivity of a simplified top mass analysis to these effects, in exclusive semi-leptonic top events at the Tevatron. A first attempt at isolating the genuine non-perturbative effects gave an estimate of order +-0.5GeV from non-perturbative uncertainties. The results presented here are an update to the original study and include recent bug fixes of Pythia that influenced the tunings investigat...
Spectral zeta function and non-perturbative effects in ABJM Fermi-gas
Hatsuda, Yasuyuki
2015-01-01
The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of "non-perturbative" poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example as...
Measurement of electric fields and estimation of dielectric susceptibility
Nogi, Yasuyuki; Suzuki, Kiyomitsu; Ohkuma, Yasunori
2013-05-01
We describe a method of measuring the spatial structures of electric fields produced by charge distributions such as those on strip electrodes, small disk electrodes, and long double-plate electrodes. An electric-field sensor with high sensitivity to ac fields is fabricated for the measurement using a thin copper sheet. The reliability of the sensor is confirmed using a parallel-plate capacitor. The electric fields are oscillated at a frequency of 300 kHz to operate the electric-field sensor successfully. The structures of the measured fields coincide well with those of theoretical fields derived from Coulomb's law. When a dielectric is inserted in an electric field, polarization charges appear on the surface of the dielectric and modify the electric field in empty space. We measure the modified field and confirm the well-known linear relation between the polarization of a dielectric and the electric field. Dielectric susceptibilities are estimated from the linear relation for four types of dielectric.
Simultaneous electric-field measurements on nearby balloons.
Mozer, F. S.
1972-01-01
Electric-field payloads were flown simultaneously on two balloons from Great Whale River, Canada, on September 21, 1971, to provide data at two points in the upper atmosphere that differed in altitude by more than one atmospheric density scale height and in horizontal position by 30-140 km. The altitude dependences in the two sets of data prove conclusively that the vertical electric field at balloon altitudes stems from fair-weather atmospheric electricity sources and that the horizontal fields are mapped down ionospheric fields, since the weather-associated horizontal fields were smaller than 2 mV/m.
Electric fields inside and outside an anisotropic dielectric sphere
Institute of Scientific and Technical Information of China (English)
Li Ying-Le; Wang Ming-Jun
2009-01-01
Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electromagnetic theory.The theoretical expressions are consistent with those in the literature. The inside electric field, the outside electric field and the angle between their directions are derived in detail. Numerical simulations show that the direction of the outside field influences the magnitude of the inside field, while the dielectric constant tensor greatly affects its direction.
Decoherence and coherence in gravitational, electric and strong nuclear fields
Silva, P R
2010-01-01
Inspired in the work of Erich Joos which appreciated the role played by matter in making the decoherence of the gravitational field, we developed an alternative way of treating the former problem. Besides this, we used the alternative approach to examine the decoherence of the electric field performed by the conduction electrons in metals. As a counterpoint, we studied the coherence of the electric color field inside nucleons, which renders the strong field a totally quantum character.
Electrical Field Effects in Phthalocyanine Film Growth by Vapor Deposition
Banks, Curtis E.; Zhu, Shen; Frazier, Donald O.; Penn, Benjamin; Abdeldayem, Hossin; Hicks, Roslin; Sarkisov, Sergey
1999-01-01
Phthalocyanine, an organic material, is a very good candidate for non-linear optical application, such as high-speed switching and optical storage devices. Phthalocyanine films have been synthesized by vapor deposition on quartz substrates. Some substrates were coated with a very thin gold film for introducing electrical field. These films have been characterized by surface morphology, material structure, chemical and thermal stability, non-linear optical parameters, and electrical behaviors. The films have excellent chemical and optical stability. However, the surface of these films grown without electrical field shows flower-like morphology. When films are deposited under an electrical field ( an aligned structure is revealed on the surface. A comparison of the optical and electrical properties and the growth mechanism for these films grown with and without an electrical field will be discussed.
Orientation of the agarose gel matrix in pulsed electric fields.
Stellwagen, J; Stellwagen, N C
1989-01-01
The technique of transient electric birefringence was used to investigate the effect of pulsed electric fields on the orientation of the agarose gel matrix. Orientation of the gel was observed at all electric field strengths. Very slow, time-dependent effects were observed when pulses of 10-100 V/cm were applied to 1% gels for 0.5-2 seconds, indicating that domains of the matrix were being oriented by the electric field. The sign of the birefringence reversed when the direction of the applied...
Fetal exposure to low frequency electric and magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Cech, R; Leitgeb, N; Pediaditis, M [Institute of Clinical Engineering, Graz University of Technology, Inffeldgasse 18, 8010 Graz (Austria)
2007-02-21
To investigate the interaction of low frequency electric and magnetic fields with pregnant women and in particular with the fetus, an anatomical voxel model of an 89 kg woman at week 30 of pregnancy was developed. Intracorporal electric current density distributions due to exposure to homogeneous 50 Hz electric and magnetic fields were calculated and results were compared with basic restrictions recommended by ICNIRP guidelines. It could be shown that the basic restriction is met within the central nervous system (CNS) of the mother at exposure to reference level of either electric or magnetic fields. However, within the fetus the basic restriction is considerably exceeded. Revision of reference levels might be necessary.
Fetal exposure to low frequency electric and magnetic fields
Cech, R.; Leitgeb, N.; Pediaditis, M.
2007-02-01
To investigate the interaction of low frequency electric and magnetic fields with pregnant women and in particular with the fetus, an anatomical voxel model of an 89 kg woman at week 30 of pregnancy was developed. Intracorporal electric current density distributions due to exposure to homogeneous 50 Hz electric and magnetic fields were calculated and results were compared with basic restrictions recommended by ICNIRP guidelines. It could be shown that the basic restriction is met within the central nervous system (CNS) of the mother at exposure to reference level of either electric or magnetic fields. However, within the fetus the basic restriction is considerably exceeded. Revision of reference levels might be necessary.
Gastric applications of electrical field stimulation.
LENUS (Irish Health Repository)
Hogan, Aisling M
2012-02-01
Advances in clinical applications of electricity have been vast since the launch of Hayman\\'s first cardiac pacemaker more than 70 years ago. Gastric electrical stimulation devices have been recently licensed for treatment of gastroparesis and preliminary studies examining their potential for use in refractory obesity yield promising results.
Electric and Magnetic Fields | RadTown USA | US EPA
2017-08-07
Electromagnetic fields (EMF) are a combination of electric and magnetic fields of energy that surround any electrical device when it is plugged in and turned on. Scientific experiments have not clearly shown whether or not exposure to EMF increases cancer risk. Scientists continue to study the issue.
The effect of pulsed electric fields on carotenoids bioaccessibility
Bot, Francesca; Verkerk, Ruud; Mastwijk, Hennie; Anese, Monica; Fogliano, Vincenzo; Capuano, Edoardo
2018-01-01
Tomato fractions were subjected to pulsed electric fields treatment combined or not with heating. Results showed that pulsed electric fields and heating applied in combination or individually induced permeabilization of cell membranes in the tomato fractions. However, no changes in β-carotene and
High School Students' Representations and Understandings of Electric Fields
Cao, Ying; Brizuela, Bárbara M.
2016-01-01
This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields post-instruction as indicated by students'…
Defect agglomeration in ferroelectric ceramics under cyclic electric field
Institute of Scientific and Technical Information of China (English)
GENG LiMing; YANG Wei
2008-01-01
The agglomeration of point defects in ferroelectric ceramics could be driven by repeated domain switching under cyclic electric field. The evolution equation of pore concentration under cyclic electric field is derived, with the help of a relation between the pore concentration and the extent of pore agglomeration. The results of the simulation agree quantitatively with the experimental data. An integrated framework about the mechanisms of electrically induced fatigue is proposed, which links the mechanisms at different scales.
Lamb-shift and electric field measurements in plasmas
Doveil, F.; Chérigier-Kovacic, L.; Ström, P.
2017-01-01
The electric field is a quantity of particular relevance in plasma physics. Indeed, its fluctuations are responsible for different macroscopic phenomena such as anomalous transport in fusion plasmas. Answering a long-standing challenge, we offer a new method to locally and non-intrusively measure weak electric fields and their fluctuations in plasmas, by means of a beam of hydrogen ions or atoms. We present measurements of the electric field in vacuum and in a plasma where Debye shielding is measured. For the first time, we have used the Lamb-shift resonance to measure oscillating electric fields around 1 GHz and observed the strong enhancement of the Lyman-α signal. The measurement is both direct and non-intrusive. This method provides sensitivity (mV cm-1) and temporal resolution (ns) that are three orders higher compared to current diagnostics. It thus allows measuring fluctuations of the electric field at scales not previously reached experimentally.
Characteristics of DC electric fields at dipolarization fronts
Laakso, Harri; Escoubet, Philippe; Masson, Arnaud
2016-04-01
We investigate the characteristics of DC electric field at dipolarization fronts and BBF's using multi-point Cluster observations. There are plenty of important issues that are considered, such as what kind of DC electric fields exist in such events and what are their spatial scales. One can also recognize if electrons and ions perform ExB drift motions in these events. To investigate this, we take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer. The calibrated observations of the three spectrometers are used to determine the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. This investigation also helps understand how well different measurements are calibrated.
Effects of geomagnetic activity on the mesospheric electric fields
Directory of Open Access Journals (Sweden)
A. M. Zadorozhny
Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes K_{p} and ∑K_{p}. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (K_{p}=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.
Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity
Effects of an electric field on white sharks: in situ testing of an electric deterrent.
Directory of Open Access Journals (Sweden)
Charlie Huveneers
Full Text Available Elasmobranchs can detect minute electromagnetic fields, <1 nV cm(-1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1 the behaviour of 18 white sharks (Carcharodon carcharias near a static bait, and (2 the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.
Novel electric field effects on Landau levels in graphene.
Lukose, Vinu; Shankar, R; Baskaran, G
2007-03-16
A new effect in graphene in the presence of crossed uniform electric and magnetic fields is predicted. Landau levels are shown to be modified in an unexpected fashion by the electric field, leading to a collapse of the spectrum, when the value of electric to magnetic field ratio exceeds a certain critical value. Our theoretical results, strikingly different from the standard 2D electron gas, are explained using a "Lorentz boost," and as an "instability of a relativistic quantum field vacuum." It is a remarkable case of emergent relativistic type phenomena in nonrelativistic graphene. We also discuss few possible experimental consequence.
Laser ablation of titanium in liquid in external electric field
Energy Technology Data Exchange (ETDEWEB)
Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)
2015-09-01
Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.
Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields.
Sutton, Gregory P; Clarke, Dominic; Morley, Erica L; Robert, Daniel
2016-06-28
Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee.
Determinants of the electric field during transcranial direct current stimulation
DEFF Research Database (Denmark)
Opitz, Alexander; Paulus, Walter; Will, Susanne
2015-01-01
Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field...... over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect...... fluid and the skull, the gyral depth and the distance to the anode and cathode. These factors account for up to 50% of the spatial variation of the electric field strength. Further, we demonstrate that individual anatomical factors can lead to stimulation "hotspots" which are partly resistant...
Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields
Sutton, Gregory P.; Clarke, Dominic; Morley, Erica L.; Robert, Daniel
2016-01-01
Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee. PMID:27247399
Noninvasive Deep Brain Stimulation via Temporally Interfering Electric Fields.
Grossman, Nir; Bono, David; Dedic, Nina; Kodandaramaiah, Suhasa B; Rudenko, Andrii; Suk, Ho-Jun; Cassara, Antonino M; Neufeld, Esra; Kuster, Niels; Tsai, Li-Huei; Pascual-Leone, Alvaro; Boyden, Edward S
2017-06-01
We report a noninvasive strategy for electrically stimulating neurons at depth. By delivering to the brain multiple electric fields at frequencies too high to recruit neural firing, but which differ by a frequency within the dynamic range of neural firing, we can electrically stimulate neurons throughout a region where interference between the multiple fields results in a prominent electric field envelope modulated at the difference frequency. We validated this temporal interference (TI) concept via modeling and physics experiments, and verified that neurons in the living mouse brain could follow the electric field envelope. We demonstrate the utility of TI stimulation by stimulating neurons in the hippocampus of living mice without recruiting neurons of the overlying cortex. Finally, we show that by altering the currents delivered to a set of immobile electrodes, we can steerably evoke different motor patterns in living mice. Copyright © 2017 Elsevier Inc. All rights reserved.
Transition of radial electric field in helical systems
Energy Technology Data Exchange (ETDEWEB)
Itoh, Kimitaka; Sanuki, Heiji; Toda, Shinichiro; Yokoyama, Masayuki [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I.; Yagi, Masatoshi [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Fukuyama, Atsushi [Kyoto Univ. (Japan). Dept. of Nuclear Engineering
2001-06-01
Transition of radial electric field is investigated in helical plasmas for the given plasma fluxes. The density and temperature gradients are simultaneously determined together with radial electric field. The electric field shows a nature of bifurcation, if an anomalous particle transport exist in addition to the neoclassical particle flux. Based on the Maxwell's construction with respect to the work-done, the critical condition for the bifurcation is obtained. The existence of bifurcation is not affected by the anomalous energy flux. The gradients are found to be subject to bifurcation at high plasma fluxes regime. The transition to a better confinement is predicted. The presence of hard transition of the gradient and electric field indicates the existence of the electric domain interface, across which the discontinuous change of gradient takes place. (author)
On the correlation analysis of electric field inside jet engine
A Krishna; Khattab, T.; Abdelaziz, A.F.; Guizani, M.
2014-01-01
A Simple channel modeling method based on correlation analysis of the electric field inside jet engine is presented. The analysis of the statistical propagation characteristics of electromagnetic field inside harsh jet engine environment is presented by using `Ansys® HFSS'. In this paper, we propose a method to locate the best position for receiving probes inside jet engine with minimum correlation between the receiver points which have strong average electric field. Moreover, a MIMO system c...
Fermionic Particle Production by Varying Electric and Magnetic Fields
Sogut, Kenan; Yanar, Hilmi; Havare, Ali
2016-11-01
Creation of fermionic particles by a time-dependent electric field and a space-dependent magnetic field is studied with the Bogoulibov transformation method. Exact analytic solutions of the Dirac equation are obtained in terms of the Whittaker functions and the particle creation number density depending on the electric and magnetic fields is determined. Supported by the Research Fund of Mersin University in TURKEY with project number: 2016-1-AP4-1425
Numerical Simulation of Modified Radial Electric Field by LHCD
Institute of Scientific and Technical Information of China (English)
Wei Wei; Ding Bojiang; Kuang Guangli
2005-01-01
Based on the electron's radial force equilibrium, the profiles of radial electric field in OH and LHCD phase are calculated by using a simulation code. The dependences of radial electron field on electron density and its profile and different current ratio, Irf/Ip, are given. The connections between the improvement of plasma confinement and the modified radial electric field by LHCD are discussed by comparing the calculated results with the experimental results.
Nonpremixed flame in a counterflow under electric fields
Park, Daegeun
2016-05-08
Electrically assisted combustion has been studied in order to control or improve flame characteristics, and emphasizing efficiency and emission regulation. Many phenomenological observations have been reported on the positive impact of electric fields on flame, however there is a lack of detailed physical mechanisms for interpreting these. To clarify the effects of electric fields on flame, I have investigated flame structure, soot formation, and flow field with ionic wind electrical current responses in nonpremixed counterflow flames. The effects of direct current (DC) electric field on flame movement and flow field was also demonstrated in premixed Bunsen flames. When a DC electric field was applied to a lower nozzle, the flames moved toward the cathode side due to Lorentz force action on the positive ions, soot particles simultaneously disappeared completely and laser diagnostics was used to identify the results from the soot particles. To understand the effects of an electric field on flames, flow visualization was performed by Mie scattering to check the ionic wind effect, which is considered to play an important role in electric field assisted combustion. Results showed a bidirectional ionic wind, with a double-stagnant flow configuration, which blew from the flame (ionic source) toward both the cathode and the anode. This implies that the electric field affects strain rate and the axial location of stoichiometry, important factors in maintaining nonpremixed counterflow flames; thus, soot formation of the counterflow flame can also be affected by the electric field. In a test of premixed Bunsen flames having parallel electrodes, flame movement toward the cathode and bidirectional ionic wind were observed. Using PIV measurement it was found that a created radial velocity caused by positive ions (i.e. toward a cathode), was much faster than the velocity toward the anode. Even in a study of alternating current (AC) electric fields, bidirectional ionic wind could
Enhancement of antibacterial properties of Ag nanorods by electric field
Directory of Open Access Journals (Sweden)
Omid Akhavan and Elham Ghaderi
2009-01-01
Full Text Available The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20–60 nm and a length of 260–550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100 thin film during its heat treatment at 700 °C in an Ar+H2 environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {100} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm−1 resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9×10−2 to 10.5×10−2 min−1. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.
Enhancement of antibacterial properties of Ag nanorods by electric field
Energy Technology Data Exchange (ETDEWEB)
Akhavan, Omid [Department of Physics, Sharif University of Technology, PO Box 11155-9161, Tehran (Iran, Islamic Republic of); Ghaderi, Elham [Tehran University of Medical Sciences, PO Box 14155-6447, Tehran (Iran, Islamic Republic of)], E-mail: oakhavan@sharif.edu
2009-01-15
The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20-60 nm and a length of 260-550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 deg. C in an Ar+H{sub 2} environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {l_brace}100{r_brace} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm{sup -1} resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9x10{sup -2} to 10.5x10{sup -2} min{sup -1}. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.
Effects of an electric field on interaction of aromatic systems.
Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S
2016-04-30
The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc.
Electric-field-assisted crystallisation in phase-change materials
Energy Technology Data Exchange (ETDEWEB)
Kohary, Krisztian; Diosdado, Jorge A.V.; Ashwin, Peter; Wright, C. David [College of Engineering, Mathematics, and Physical Sciences, University of Exeter (United Kingdom)
2012-10-15
Phase-change materials are of intense research interest due mainly to their use in phase-change memory (PCM) devices that are emerging as a promising technology for future non-volatile, solid-state, electrical storage. Electrically driven transitions from the amorphous to the crystalline phase in such devices exhibit characteristic threshold switching. Several alternative electronic explanations for the origins of this characteristic behaviour have been put forward, for example Poole-Frenkel effects, delocalisation of tail states, field emission processes and space charge limited currents [for a full discussion, see Radielli et al., J. Appl. Phys. 103, 111101 (2008) and Simon et al., MRS Proc. 1251, H01-H011 (2010)]. However, an alternative to these conventional electronic models of threshold switching is based on electric field induced lowering of the system free energy, leading to the field induced nucleation of conducting crystal filaments. In this paper we investigate this alternative view. We present a detailed kinetics study of crystallisation in the presence of an electric field for the phase-change material Ge{sub 2}Sb{sub 2}Te{sub 5}. We derive quantitative crystallisation maps to show the effects of both temperature and electric field on crystallisation and we identify field ranges and parameter values where the electric field might play a significant role. Then we carry out physically realistic simulations of the threshold switching process in typical phase-change device structures, both with and without electric field dependent energy contributions to the system free energy. Our results show that threshold switching can be obtained by a mechanism driven purely by electric field induced nucleation, but the fields so required are large, of the order of 300 MV m{sup -1}, and significantly larger than the experimentally measured threshold fields. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Non-perturbative renormalisation of four-fermion operators in $N_f=2$ QCD
Dimopoulos, P; Palombi, Filippo; Papinutto, Mauro; Peña, C; Vladikas, A; Wittig, H
2007-01-01
We present results for the non-perturbative renormalisation of four-fermion operators with two flavours of dynamical quarks. We consider both fully relativistic left current-left current operators, and a full basis for $\\Delta B=2$ operators with static heavy quarks. The renormalisation group running of the operators to high energy scales is computed in the continuum limit for a family of Schroedinger Functional renormalisation schemes, via standard finite size scaling techniques. The total renormalisation factors relating renormalisation group invariant to bare operators are computed for a choice of lattice regularisations.
Do fragmentation functions in factorization theorems correctly treat non-perturbative effects?
Collins, John
2016-01-01
Current all-orders proofs of factorization of hard processes are made by extracting the leading power behavior of Feynman graphs, i.e., by extracting asymptotics strictly order-by-order in perturbation theory. The resulting parton densities and fragmentation functions include non-perturbative effects. I show how there are missing elements in the proofs; these are related to and exemplified by string and cluster models of hadronization. The proofs rely on large rapidity differences between different parts of graphs for the process; but in reality large rapidity gaps are filled in
Non-perturbative Calculation of the Positronium Mass Spectrum in Basis Light-Front Quantization
Wiecki, Paul; Zhao, Xingbo; Maris, Pieter; Vary, James P
2015-01-01
We report on recent improvements to our non-perturbative calculation of the positronium spectrum. Our Hamiltonian is a two-body effective interaction which incorporates one-photon exchange terms, but neglects fermion self-energy effects. This effective Hamiltonian is diagonalized numerically in a harmonic oscillator basis at strong coupling ($\\alpha=0.3$) to obtain the mass eigenvalues. We find that the mass spectrum compares favorably to the Bohr spectrum of non-relativistic quantum mechanics evaluated at this unphysical coupling.
A Non-Perturbative Approach to the Random-Bond Ising Model
Cabra, D C; Mussardo, G; Pujol, P
1997-01-01
We study the N -> 0 limit of the O(N) Gross-Neveu model in the framework of the massless form-factor approach. This model is related to the continuum limit of the Ising model with random bonds via the replica method. We discuss how this method may be useful in calculating correlation functions of physical operators. The identification of non-perturbative fixed points of the O(N) Gross-Neveu model is pursued by its mapping to a WZW model.
B-physics from non-perturbatively renormalized HQET in two-flavour lattice QCD
Bernardoni, Fabio; Bulava, John; Della Morte, Michele; Fritzsch, Patrick; Garron, Nicolas; Gerardin, Antoine; Heitger, Jochen; von Hippel, Georg M; Simma, Hubert
2013-01-01
We report on the ALPHA Collaboration's lattice B-physics programme based on N_f=2 O(a) improved Wilson fermions and HQET, including all NLO effects in the inverse heavy quark mass, as well as non-perturbative renormalization and matching, to fix the parameters of the effective theory. Our simulations in large physical volume cover 3 lattice spacings a ~ (0.08-0.05) fm and pion masses down to 190 MeV to control continuum and chiral extrapolations. We present the status of results for the b-quark mass and the B_(s)-meson decay constants, f_B and f_{B_s}.
Non-perturbative fixed points and renormalization group improved effective potential
Directory of Open Access Journals (Sweden)
A.G. Dias
2014-12-01
Full Text Available The stability conditions of a renormalization group improved effective potential have been discussed in the case of scalar QED and QCD with a colorless scalar. We calculate the same potential in these models assuming the existence of non-perturbative fixed points associated with a conformal phase. In the case of scalar QED the barrier of instability found previously is barely displaced as we approach the fixed point, and in the case of QCD with a colorless scalar not only the barrier is changed but the local minimum of the potential is also changed.
Non-perturbative gluons in diffractive photo-production of J/Psi
Ducati, M B G; Sauter, Werner K.
2001-01-01
The modifications induced in the calculation of the cross section of the diffractive process gamma gamma -> J/Psi J/Psi when the gluon propagator is changed are analyzed. Instead of the usual perturbative gluon propagator, alternative forms obtained using non-perturbative methods like Dyson-Schwinger equations are used to consider in a more consistent way the contributions of the infrared region. The result shows a reduction in the differential cross-section for low momentum transfer once compared with the perturbative result, to be confirmed with future experimental results from TESLA.
Non-perturbative renormalization of quark bilinear operators and B_K using domain wall fermions
Aoki, Y; Christ, N H; Dawson, C; Donnellan, M A; Izubuchi, T; Juttner, A; Li, S; Mawhinney, R D; Noaki, J; Sachrajda, Christopher T C; Soni, A; Tweedie, R J; Yamaguchi, A
2007-01-01
We present a calculation of the renormalization coefficients of the quark bilinear operators and the K-Kbar mixing parameter B_K. The coefficients relating the bare lattice operators to those in the RI/MOM scheme are computed non-perturbatively and then matched perturbatively to the MSbar scheme. The coefficients are calculated on the RBC/UKQCD 2+1 flavor dynamical lattice configurations. Specifically we use a 16^3 x 32 lattice volume, the Iwasaki gauge action at beta=2.13 and domain wall fermions with L_s=16.
Stable Non--Perturbative Minimal Models Coupled to 2D Quantum Gravity
Johnson, C; Spence, B; Johnson, Clifford; Morris, Tim; Spence, Bill
1992-01-01
A generalisation of the non--perturbatively stable solutions of string equations which respect the KdV flows, obtained recently for the $(2m-1,2)$ conformal minimal models coupled to two--dimensional quantum gravity, is presented for the $(p,q)$ models. These string equations are the most general string equations compatible with the $q$--th generalised KdV flows. They exhibit a close relationship with the bi-hamiltonian structure in these hierarchies. The Ising model is studied as a particular example, for which a real non-singular numerical solution to the string susceptibility is presented.
Electric field gradients in Hg compounds
DEFF Research Database (Denmark)
Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.
2012-01-01
We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by compar......We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved...
Scattering and pair creation by L-constant electric field
Gavrilov, S P
2015-01-01
Using QFT approach developed by us in Ref. arXiv:1506.01156, we consider particle scattering and vacuum instability in the so-called L-constant electric field, which is a constant electric field confined between two capacitor plates separated by a finite distance L. We obtain and analyze special sets of stationary solutions of the Dirac and Klein-Gordon equations with the L-constant electric field. Then, we represent probabilities of particle scattering and characteristics of the vacuum instability (related to the pair creation) in terms of the introduced solutions. From exact formulas, we derive asymptotic expressions for the differential mean numbers, for the total mean number of created particles, and for the vacuum-to-vacuum transition probability. Using the equivalence principle, we demonstrate that the distributions of created particles by L-constant electric field and gravitational field of a black hole have similar thermal structure.
Relationship between large horizontal electric fields and auroral arc elements
Energy Technology Data Exchange (ETDEWEB)
Lanchester, B.S. [Univ. of Southampton (United Kingdom); Kaila, K. [Univ. of Oulu (Finland); McCrea, I.W. [Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom)
1996-03-01
The authors report on data which correlates high time resolution optical measurements of auroral features with EISCAT radar measurements of electron density, with 0.2 sec time resolution and horizontal electric field, with time resolution near 9 sec. The associations between such electric fields and auroral arc features have been a subject of interest for years. They report on one event where following an auroral breakup, an arc moved southward. During 30 seconds of this event a section of the arc was close to the radar beam, and better resolution was available for the electric field measurements. The results indicate that the electric field pointed towards the point of brightest emission in the arc, indicating that the fields might be associated with the charged-particle precipitation causing the bright features in the arc.
[Mechanism of ablation with nanosecond pulsed electric field].
Cen, Chao; Chen, Xin-hua; Zheng, Shu-sen
2015-11-01
Nanosecond pulsed electric field ablation has been widely applied in clinical cancer treatment, while its molecular mechanism is still unclear. Researchers have revealed that nanosecond pulsed electric field generates nanopores in plasma membrane, leading to a rapid influx of Ca²⁺; it has specific effect on intracellular organelle membranes, resulting in endoplasmic reticulum injuries and mitochondrial membrane potential changes. In addition, it may also change cellular morphology through damage of cytoskeleton. This article reviews the recent research advances on the molecular mechanism of cell membrane and organelle changes induced by nanosecond pulsed electric field ablation.
Solar Wind Electric Fields in the Ion Cyclotron Frequency Range
Kellogg, P J; Mozer, F S; Horbury, T S; Reme, H
2006-01-01
Measurements of fluctuations of electric fields in the frequency range from a fraction of one Hz to 12.5 Hz are presented, and corrected for the Lorentz transformation of magnetic fluctuations to give the electric fields in the plasma frame. The electric fields are large enough to provide the dominant force on the ions of the solar wind in the region near the ion cyclotron frequency of protons, larger than the force due to magnetic fluctuations. They provide sufficient velocity space diffusion or heating to counteract conservation of magnetic moment in the expanding solar wind to maintain nearly isotropic velocity distributions.
Effects of Orthogonal Rotating Electric Fields on Electrospinning Process
Cipolletta, Federico; Pontrelli, Giuseppe; Pisignano, Dario; Succi, Sauro
2016-01-01
Electrospinning is an nanotechnology process whereby an external electric field is used to accelerate and stretch a charged polymer jet, so as to produce fibers at nanoscale diameters. In quest of a further reduction in the cross section of electrified jets hence of the resulting electrospun fibers, we explore the effects of an external rotating electric field orthogonal to the jet direction. Through extensive particle simulations, it is shown that by a proper tuning of the electric field amplitude and frequency, a reduction of up to a 30% in the aforementioned radius can be obtained, thereby opening new perspectives in the design of future ultra-thin electrospun fibres.
High Dynamic Range Electric Field Sensor for Electromagnetic Pulse Detection
Lin, Che-Yun; Lee, Beom Suk; Zhang, Xingyu; Chen, Ray T
2014-01-01
We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.
Giant and tunable electric field enhancement in the terahertz regime.
Lu, Xiaoyuan; Wan, Rengang; Wang, Guoxi; Zhang, Tongyi; Zhang, Wenfu
2014-11-01
A novel array of slits design combining the nano-slit grating and dielectric-metal is proposed to obtain giant and tunable electric field enhancement in the terahertz regime. The maximum amplitude of electric field is more than 6000 times larger than that of the incident electric field. It is found that the enhancement depends primarily on the stripe and nano-slits width of grating, as well as the thickness of spacer layer. This property is particularly beneficial for the realization of ultra-sensitive nanoparticles detection and nonlinear optics in the terahertz range, such as the second harmonic generation (SHG).
Salengke, dkk
2012-01-01
Innovations and technology developments in the field of food pasteurization and sterilization are continuously evolving. These include innovations in thermal processing technologies such as aseptic processing, ohmic technology, and microwave technology, as well as non-thermal processing technologies which include pulsed electric field technology and high pressure processing technology. This paper discussed the results of a study on mathematical modeling of electric field and temperature distr...
Synthesis of zirconium oxynitride in air under DC electric fields
Morisaki, Nobuhiro; Yoshida, Hidehiro; Matsui, Koji; Tokunaga, Tomoharu; Sasaki, Katsuhiro; Yamamoto, Takahisa
2016-08-01
We synthesized zirconium oxynitride from yttria-stabilized zirconia (YSZ) in air by applying DC electric fields that produced a controlled electric current in the specimen. When YSZ was heated under an applied DC electric field, the electric current of the specimen steeply increased at a critical temperature, called a flash event, during flash sintering. By keeping the electric current of the specimen constant during the flash event and then holding the specimen at the critical temperature, YSZ was transformed into zirconium oxynitride under the optimal conditions of 50 V/cm, 500 mA, and 1000 °C. We confirmed that zirconium oxynitride formed using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and energy-dispersive spectrometry. To convert oxides to nitrides, reducing conditions are necessary to form excess oxygen vacancies. Our technique produced the strong reducing conditions necessary to form nitrides from the oxides by delivering a controlled electric current to the specimen.
High-frequency electric field amplification in a magnetized plasma
Energy Technology Data Exchange (ETDEWEB)
Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)
2006-11-30
In the investigation of cyclotron ion heating in systems designed for plasma isotope separation, the high-frequency (HF) electric field amplification effect was found to occur in equilibrium plasma. In the present article this effect is treated as a result of the interaction of the plasma placed in a constant external magnetic field with the HF modes of the vacuum chamber. Consistent elaboration of this approach allowed obtaining a clear interpretation of the HF electric field amplification effect and constructing a simple model of HF field excitation in a plasma column embedded in the external magnetic field. (methodological notes)
Effects of an electric field on white sharks: in situ testing of an electric deterrent.
Huveneers, Charlie; Rogers, Paul J; Semmens, Jayson M; Beckmann, Crystal; Kock, Alison A; Page, Brad; Goldsworthy, Simon D
2013-01-01
Elasmobranchs can detect minute electromagnetic fields, shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.
Formation of Organized Protein Thin Films with External Electric Field.
Ferreira, Cecília Fabiana da G; Camargo, Paulo C; Benelli, Elaine M
2015-10-01
The effect of an external electric field on the formation of protein GlnB-Hs films and on its buffer solution on siliconized glass slides has been analyzed by current versus electric field curves and atomic force microscopy (AFM). The Herbaspirillum seropedicae GlnB protein (GlnB-Hs) is a globular, soluble homotrimer (36 kDa) with its 3-D structure previously determined. Concentrations of 10 nM native denatured GlnB-Hs protein were deposited on siliconized glass slides under ambient conditions. Immediately after solution deposition a maximum electric field of 30 kV/m was applied with rates of 3 V/s. The measured currents were surface currents and were analyzed as transport current. Electric current started to flow only after a minimum electric field (critical value) for the systems analyzed. The AFM images showed films with a high degree of directional organization only when the proteins were present in the solution. These results showed that the applied electric field favored directional organization of the protein GlnB-Hs films and may contribute to understand the formation of protein films under applied electric fields.
The bee, the flower and the electric field
Directory of Open Access Journals (Sweden)
Robert Daniel
2016-01-01
Full Text Available Insects use several different senses to forage on flowers, and detect floral cues such as color, shape, pattern, humidity and chemical volatiles. This presentation will present our discovery of a previously unappreciated sensory capacity in bumblebees (Bombus terrestris: the detection of floral electric fields. We show that these floral fields act as informational cues, and that they can be affected by the visit of naturally electrically charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator’s memory of floral rewards. Floral electric fields arise from complex interactions with the surrounding atmosphere, an interaction between plants and their environment that not well understood. Because floral electric fields can change within seconds, this new sensory modality - electrostatic field detection- may facilitate rapid and dynamic communication between flowers and their pollinators.
EFFECT OF ELECTRIC FIELD ON CONTINUOUS LIQUID STREAM
The effect of an electrical field on a continous water jet is considered. The higher electrification of water jets, the more intense are jet sprays...It seems possible to contract an electrized water jet by letting it pass the cylinder charged with the same sign. An attempt to electrify kerosene and spindel oil jets (good insulators) was unsucessful.
Magnetic domain wall motion triggered by electric field
Energy Technology Data Exchange (ETDEWEB)
Pyatakov, A P; Sergeev, A S; Sechin, D A; Meshkov, G A; Nikolaeva, E P; Nikolaev, A V; Logginov, A S [Physics Department, M.V. Lomonosov Moscow State University, Leninskie gory, Moscow, 119296 (Russian Federation); Zvezdin, A K, E-mail: pyatakov@phys.msu.r [A.M. Prokhorov General Physics Institute, 38, Vavilova st., Moscow, 119991 (Russian Federation)
2010-01-01
We propose the new approach to the problem of electrically controlled magnetic state: the electric field driven domain wall motion. The effect is demonstrated in iron garnet films in ambient conditions. The theoretical model based on inhomogenous magnetoelectric interaction provides with the necessary criteria of the effect and the way to maximize it.
Electric and magnetic field measurements. Annual report 80
Energy Technology Data Exchange (ETDEWEB)
McKnight, R.H.; Kotter, F.R.; Misakian, M.; Ortiz, P.
1981-02-01
The NBS program is concerned with developing methods for evaluating and calibrating instrumentation for use in measuring the electric field and various ion-related electrical quantities in the vicinity of high-voltage direct current (HVDC) transmission lines and in apparatus designed to simulate the transmission line environment.
Generation of Focused Electric Field Patterns at Dielectric Surfaces
Olofsson, Jessica; Levin, Mikael; Strömberg, Anette; Weber, Stephen G.; Ryttsén, Frida; Orwar, Owe
2006-01-01
We here report on a concept for creating well-defined electric field gradients between the boundaries of capillary electrode (a capillary of a nonconducting material equipped with an interior metal electrode) outlets, and dielectric surfaces. By keeping a capillary electrode opening close to a boundary between a conducting solution and a nonconducting medium, a high electric field can be created close to the interface by field focusing effects. By varying the inner and outer diameters of the capillary, the span of electric field strengths and the field gradient obtained can be controlled, and by varying the slit height between the capillary rim and the surface, or the applied current, the average field strength and gradient can be varied. Field focusing effects and generation of electric field patterns were analyzed using finite element method simulations. We experimentally verified the method by electroporation of a fluorescent dye (fluorescein diphosphate) into adherent, monolayered cells (PC-12 and WSS-1) and obtained a pattern of fluorescent cells corresponding to the focused electric field. PMID:16013887
Canfora, Fabrizio; Pais, Pablo; Rosa, Luigi; Zerwekh, Alfonso
2016-01-01
In this paper it is analyzed the compatibility of the non-perturbative equations of state of quarks and gluons arising from the lattice with some natural requirements for self gravitating objects at equilibrium: the existence of an equation of state (namely, the possibility to define the pressure as a function of the energy density), the absence of superluminal propagation and Le Chatelier's principle. It is discussed under which conditions it is possible to extract an equation of state (in the above sense) from the non-perturbative propagators arising from the fits of the last lattice data. In particular, in the quarks case, there is a small but non vanishing range of temperatures in which it is not possible to define a single-valued functional relation between density and pressure. Interestingly enough, a small change of the parameters appearing in the fit of the lattice quark propagator (of around 10\\%) can guarantee the fulfillment of all the three conditions (keeping alive, at the same time, the violatio...
ER= EPR and Non-Perturbative Action Integrals for Quantum Gravity
Alasfar, L A
2016-01-01
In this paper, we summarise a conjuncture for constructing and calculating path integrals (in non perturbative fashion ) by summing over homotopy classes of paths in a multiply-connected spacetime. The topology of the spacetime is defined by Einstein-Rosen bridges (ERB) forming from the entanglement of Wheeler's quantum foam described by S.W Hawking paper 'Virtual Blackholes' (Phys.Rev. D53 (1996) 3099-3107). Because these 'bubbles' are entangled, they are connected by Plankian ERB's by the ER=EPR conjecture of L. Susskind Hence the spacetime will possess a large first Betti number $ B_1$. For any compact 2-surface in the spacetime, the topology ( in particular the homotopy ) of that surface is not trivial, due to the large number of Plankian ERB's that define homotopy though this surface. The quantisation of spacetime with this topology - along with the proper choice of the 2-surfaces- is conjectured to allow a non perturbative path integrals of quantum gravity theory over the spacetime manifold. The task is...
Non-perturbative renormalization of tensor bilinears in Schr\\"odinger Functional schemes
Fritzsch, Patrick; Preti, David
2015-01-01
We present preliminary result for the study of the renormalization group evolution of tensor bilinears in Schr\\"odinger Functional (SF) schemes for $N_f=0$ and $N_f=2$ QCD with non-perturbatively $\\mathcal{O}(a)$-improved Wilson fermions. First $N_f=2+1$ results (proceeding in parallel with the ongoing computation of the running quark masses [1] are also discussed. A one-loop perturbative calculation of the discretisation effects for the relevant step scaling functions has been carried out for both Wilson and $\\mathcal{O}(a)$-improved actions and for a large number of lattice resolutions. We also calculate the two-loop anomalous dimension in SF schemes for tensor currents through a scheme matching procedure with RI and $\\overline{\\rm MS}$. Thanks to the SF iterative procedure the non-perturbative running over two orders of magnitude in energy scales, as well as the corresponding Renormalization Group Invariant operators, have been determined.
Non-perturbative renormalization of the static axial current in two-flavour QCD
Della Morte, M; Heitger, J; Fritzsch, Patrick; Heitger, Jochen; Morte, Michele Della
2007-01-01
We perform the non-perturbative renormalization of matrix elements of the static-light axial current by a computation of its scale dependence in lattice QCD with two flavours of massless O(a) improved Wilson quarks. The regularization independent factor that relates any running renormalized matrix element of the axial current in the static effective theory to the renormalization group invariant one is evaluated in the Schroedinger functional scheme, where in this case we find a significant deviation of the non-perturbative running from the perturbative prediction. An important technical ingredient to improve the precision of the results consists in the use of modified discretizations of the static quark action introduced earlier by our collaboration. As an illustration how to apply the renormalization of the static axial current presented here, we connect the bare matrix element of the current to the B_s-meson decay constant in the static approximation for one value of the lattice spacing, a ~ 0.08 fm, employ...
Interferometric methods for mapping static electric and magnetic fields
DEFF Research Database (Denmark)
Pozzi, Giulio; Beleggia, Marco; Kasama, Takeshi;
2014-01-01
The mapping of static electric and magnetic fields using electron probes with a resolution and sensitivity that are sufficient to reveal nanoscale features in materials requires the use of phase-sensitive methods such as the shadow technique, coherent Foucault imaging and the Transport of Intensi......) the model-independent determination of the locations and magnitudes of field sources (electric charges and magnetic dipoles) directly from electron holographic data.......The mapping of static electric and magnetic fields using electron probes with a resolution and sensitivity that are sufficient to reveal nanoscale features in materials requires the use of phase-sensitive methods such as the shadow technique, coherent Foucault imaging and the Transport of Intensity...... on theoretical models that form the basis of the quantitative interpretation of electron holographic data. We review the application of electron holography to a variety of samples (including electric fields associated with p–n junctions in semiconductors, quantized magnetic flux in superconductors...
Communication: Control of chemical reactions using electric field gradients.
Deshmukh, Shivaraj D; Tsori, Yoav
2016-05-21
We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.
Probing surface electric field noise with a single ion
Daniilidis, N; Bolloten, G; Ramm, M; Ransford, A; Ulin-Avila, E; Talukdar, I; Häffner, H
2013-01-01
We report room-temperature electric field noise measurements combined with in-situ surface characterization and cleaning of a microfabricated ion trap. We used a single-ion electric field noise sensor in combination with surface cleaning and analysis tools, to investigate the relationship between electric field noise from metal surfaces in vacuum and the composition of the surface. These experiments were performed in a novel setup that integrates ion trapping capabilities with surface analysis tools. We find that surface cleaning of an aluminum-copper surface significantly reduces the level of electric field noise, but the surface does not need to be atomically clean to show noise levels comparable to those of the best cryogenic traps. The post-cleaning noise levels are low enough to allow fault-tolerant trapped-ion quantum information processing on a microfabricated surface trap.
Direct sampling of electric-field vacuum fluctuations
National Research Council Canada - National Science Library
Riek, C; Seletskiy, D V; Moskalenko, A S; Schmidt, J F; Krauspe, P; Eckart, S; Eggert, S; Burkard, G; Leitenstorfer, A
2015-01-01
.... The ground-state electric-field variance is inversely proportional to the four-dimensional space-time volume, which we sampled electro-optically with tightly focused laser pulses lasting a few femtoseconds...
Communication: Control of chemical reactions using electric field gradients
Deshmukh, Shivaraj D.; Tsori, Yoav
2016-05-01
We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.
Bishop, David M.; Cybulski, sławomir M.
1994-05-01
Electric field gradients, generalized Sternheimer shielding constants, and electric-field-gradient polarizabilities are calculated for H2, N2, F2, HF, HCl, CO, HCN, HNC, H2O, and NH3. The calculations are performed at both the Hartree-Fock and second order Møller-Plesset levels of approximation using large basis sets. For most of these molecules this is the first time that the shielding constants and electric field gradient polarizabilities have been determined. Electron correlation is generally found to be a significant factor.
Effective critical electric field for runaway electron generation
Stahl, Adam; Decker, Joan; Embréus, Ola; Fülöp, Tünde
2014-01-01
In this letter we investigate factors that influence the effective critical electric field for runaway electron generation in plasmas. We present numerical solutions of the kinetic equation, and discuss the implications for the threshold electric field. We show that the effective electric field necessary for significant runaway formation often is higher than previously calculated due to both (1) extremely strong dependence of primary generation on temperature, and (2) synchrotron radiation losses. We also address the effective critical field in the context of a transition from runaway growth to decay. We find agreement with recent experiments, but show that the observation of an elevated effective critical field can mainly be attributed to changes in the momentum-space distribution of runaways, and only to a lesser extent to a de facto change in the critical field.
Drop oscillation and mass transfer in alternating electric fields
Energy Technology Data Exchange (ETDEWEB)
Carleson, T.E.
1992-06-24
In certain cases droplet direct contact heat transfer rates can be significantly enhanced by the application of an alternating electric field. This field can produce shape oscillations in a droplet which will enhance mixing. The theoretical evaluation of the effect of the interaction of the field with drop charge on the hydrodynamics has been completed for small amplitude oscillations. Previous work with a zero order perturbation method was followed up with a first order perturbation method to evaluate the effect of drop distortion on drop charge and field distribution. The first order perturbation results show secondary drop oscillations of four modes and two frequencies in each mode. The most significant secondary oscillation has the same mode and frequency as the second mode oscillation predicted from the first order perturbation work. The resonant frequency of all oscillations decrease with increasing electric field strength and drop charge. Work is currently underway to evaluate the heat transfer enhancement from an applied alternating electric field.
Electric field effects in hyperexcitable neural tissue: A review
Energy Technology Data Exchange (ETDEWEB)
Durand, D.M
2003-07-01
Uniform electric fields applied to neural tissue can modulate neuronal excitability with a threshold value of about 1mV mm{sup -1} in normal physiological conditions. However, electric fields could have a lower threshold in conditions where field sensitivity is enhanced, such as those simulating epilepsy. Uniform electrical fields were applied to hippocampal brain slices exposed to picrotoxin, high potassium or low calcium solutions. The results in the low calcium medium show that neuronal activity can be completely blocked in 10% of the 30 slices tested with a field amplitude of 1mV mm{sup -1}. These results suggest that the threshold for this effect is clearly smaller than 1mV mm{sup -1}. The hypothesis that the extracellular resistance could affect the sensitivity to the electrical fields was tested by measuring the effect of the osmolarity of the extracellular solution on the efficacy of the field. A 10% decrease on osmolarity resulted in a 56% decrease (n=4) in the minimum field required for full suppression. A 14% in osmolarity produced an 81% increase in the minimum field required for full suppression. These results show that the extracellular volume can modulate the efficacy of the field and could lower the threshold field amplitudes to values lower than {approx}1mmV mm{sup -.} (author)
Anomalous plasma transport and induced electric field in a stochastic magnetic field structure
Energy Technology Data Exchange (ETDEWEB)
Kubota, Tetsuyuki; Itoh, Sanae-I.; Toda, Shinichiro; Yamaguchi, Hiroki [Kyushu Univ., Fukuoka (Japan); Fukuyama, Atsushi [Okayama Univ. (Japan)
1995-04-01
The plasma transport matrix is formulated using the kinetic equation for the particles in the stochastic magnetic field. The radial electric field generation is analyzed using this transport matrix. This thermoelectric field is dictated by the difference between the electron heat flux and the ion heat flux. We calculate the spatial structures of the radial electric field and the temperature in the stochastic field region. 7 refs., 3 figs.
Evolution of Spiral Waves under Modulated Electric Fields
Institute of Scientific and Technical Information of China (English)
MA Jun; YING He-Ping; PAN Guo-Wei; PU Zhong-Sheng
2005-01-01
@@ Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.
Electric field dependence of crystallinity in poly(vinylidene fluoride)
Energy Technology Data Exchange (ETDEWEB)
Kepler, R.G.; Anderson, R.A.; Lagasse, R.R.
1982-05-03
It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).
Electric Field Dependence of Crystallinity in Poly(Vinylidene Fluoride)
Kepler, R. G.; Anderson, R. A.; Lagasse, R. R.
1982-05-01
It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).
Ionizing gas breakdown waves in strong electric fields.
Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.
1972-01-01
A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.
Spiral Wave Generation in a Vortex Electric Field
Institute of Scientific and Technical Information of China (English)
YUAN Xiao-Ping; CHEN Jiang-Xing; ZHAO Ye-Hua; LOU Qin; WANG Lu-Lu; SIIEN Qian
2011-01-01
The effect of a vortical electric field on nonlinear patterns in excitable media is studied. When an appropriate vortex electric field is applied, the system exhibits pattern transition from chemical turbulence to spiral waves, which possess the same chtality as the vortex electric field. The underlying mechanism of this is discussed. We also show the meandering behavior of a spiral under the taming of a vortex electric field. The results obtained here may contribute to control strategies of patterns on surface reaction.%The effect of a vortical electric field on nonlinear patterns in excitable media is studied.When an appropriate vortex electric field is applied,the system exhibits pattern transition from chemical turbulence to spiral waves,which possess the same chirality as the vortex electric field.The underlying mechanism of this is discussed.We also show the meandering behavior of a spiral under the taming of a vortex electric field.The results obtained here may contribute to control strategies of patterns on surface reaction.Spiral waves are one of the most common and widely studied patterns in nature.They appear in hydrodynamic systems,chemical reactions and a large variety of biological,chemical and physical systems.[1-5] Much attention has been paid to their rich nonlinear dynamics,as well as potential applications in various biological or physiological systems,since the emergence and instability of spirals usually lead to abnormal states,for example in cardiac arrythmia[6,7] and epilepsy[8].Much research has been carried out in studying pattern formations in catalytic CO oxidation on Pt(110),[9-11] because they provide practical utilization in industry.A rich variety of spatiotemporal patterns,including travelling pulses,standing waves,target patterns,spiral waves and chemical turbulence have been observed in this system.[12-16
Directory of Open Access Journals (Sweden)
Tofy Mussivand
2013-06-01
Full Text Available Analysis of electric fields generated inside the microchannels of a microfluidic device for electrical lysis of biological cells along with experimental verification are presented. Electrical lysis is the complete disintegration of cell membranes, due to a critical level of electric fields applied for a critical duration on a biological cell. Generating an electric field inside a microchannel of a microfluidic device has many advantages, including the efficient utilization of energy and low-current requirement. An ideal microchannel model was compared with a practical microchannel model using a finite element analysis tool that suggests that the overestimation error can be over 10%, from 2.5 mm or smaller, in the length of a microchannel. Two analytical forms are proposed to reduce this overestimation error. Experimental results showed that the high electric field is confined only inside the microchannel that is in agreement with the simulation results. Single cell electrical lysis was conducted with a fabricated microfluidic device. An average of 800 V for seven seconds across an 8 mm-long microchannel with the dimension of 100 μm × 20 μm was required for lysis, with electric fields exceeding 100 kV/m and consuming 300 mW.
Electric Field-Induced Fluid Velocity Field Distribution in DNA Solution
Institute of Scientific and Technical Information of China (English)
ZHANG Ling-Yun; WANG Peng-Ye
2008-01-01
We present an analytical solution for fluid velocity field distribution of polyelectrolyte DNA. Both the electric field force and the viscous force in the DNA solution are considered under a suitable boundary condition. The solution of electric potential is analytically obtained by using the linearized Poisson-Boltzmann equation. The fluid velocity along the electric field is dependent on the cylindrical radius and concentration. It is shown that the electric field-induced fluid velocity will be increased with the increasing cylindrical radius, whose distribution also varies with the concentration
Effects of high external electric fields on protein conformation
Pompa, Pier Paolo; Bramanti, Alessandro; Maruccio, Giuseppe; del Mercato, Loretta Laureana; Chiuri, Rocco; Cingolani, Roberto; Rinaldi, Ross
2005-06-01
Resistance of biomolecules to high electric fields is a main concern for nanobioelectronics/nanobiosensing applications, and it is also a relevant issue from a fundamental perspective, to understand the dielectric properties and structural dynamics of proteins. In nanoscale devices, biomolecules may experience electric fields as high as 107 V/m in order to elicit charge transport/transfer. Understanding the effects of such fields on their structural integrity is thus crucial to assess the reliability of biomolecular devices. In this study, we show experimental evidence for the retention of native-like fold pattern by proteins embedded in high electric fields. We have tested the metalloprotein azurin, deposited onto SiO2 substrates in air with proper electrode configuration, by applying high static electric fields (up to 106-107 V/m). The effects on the conformational properties of protein molecules have been determined by means of intrinsic fluorescence measurements. Experimental results indicate that no significant field-induced conformational alteration occurs. This behavior is also discussed and supported by theoretical predictions of the intrinsic intra-protein electric fields. As the general features of such inner fields are not peculiar of azurin, the conclusions presented here should have general validity.
Particle acceleration by fluctuating electric fields at a magnetic field null point
Petkaki, P
2007-01-01
Particle acceleration consequences from fluctuating electric fields superposed on an X-type magnetic field in collisionless solar plasma are studied. Such a system is chosen to mimic generic features of dynamic reconnection, or the reconnective dissipation of a linear disturbance. We explore numerically the consequences for charged particle distributions of fluctuating electric fields superposed on an X-type magnetic field. Particle distributions are obtained by numerically integrating individual charged particle orbits when a time varying electric field is superimposed on a static X-type neutral point. This configuration represents the effects of the passage of a generic MHD disturbance through such a system. Different frequencies of the electric field are used, representing different possible types of wave. The electric field reduces with increasing distance from the X-type neutral point as in linear dynamic magnetic reconnection. The resulting particle distributions have properties that depend on the ampli...
Migration of amoeba cells in an electric field
Guido, Isabella; Bodenschatz, Eberhard
2015-03-01
Exogenous and endogenous electric fields play a role in cell physiology as a guiding mechanism for the orientation and migration of cells. Electrotaxis of living cells has been observed for several cell types, e.g. neurons, fibroblasts, leukocytes, neural crest cells, cancer cells. Dictyostelium discoideum (Dd), an intensively investigated chemotactic model organism, also exhibits a strong electrotactic behavior moving toward the cathode under the influence of electric fields. Here we report experiments on the effects of DC electric fields on the directional migration of Dd cells. We apply the electric field to cells seeded into microfluidic devices equipped with agar bridges to avoid any harmful effects of the electric field on the cells (ions formation, pH changes, etc.) and a constant flow to prevent the build-up of chemical gradient that elicits chemotaxis. Our results show that the cells linearly increase their speed over time when a constant electric field is applied for a prolonged duration (2 hours). This novel phenomenon cannot be attributed to mechanotaxis as the drag force of the electroosmotic flow is too small to produce shear forces that can reorient cells. It is independent of the cellular developmental stage and to our knowledge, it was not observed in chemotaxis. This work is supported by MaxSynBio project of the Max Planck Society.
Effect of superheat and electric field on saturated film boiling
Pandey, Vinod; Biswas, Gautam; Dalal, Amaresh
2016-05-01
The objective of this investigation is to study the influence of superheat temperature and applied uniform electric field across the liquid-vapor interface during film boiling using a coupled level set and volume of fluid algorithm. The hydrodynamics of bubble growth, detachment, and its morphological variation with electrohydrodynamic forces are studied considering the medium to be incompressible, viscous, and perfectly dielectric at near critical pressure. The transition in interfacial instability behavior occurs with increase in superheat, the bubble release being periodic both in space and time. Discrete bubble growth occurs at a smaller superheat whereas vapor columns form at the higher superheat values. Destabilization of interfacial motion due to applied electric field results in decrease in bubble separation distance and increase in bubble release rate culminating in enhanced heat transfer rate. A comparison of maximum bubble height owing to application of different intensities of electric field is performed at a smaller superheat. The change in dynamics of bubble growth due to increasing superheat at a high intensity of electric field is studied. The effect of increasing intensity of electric field on the heat transfer rate at different superheats is determined. The boiling characteristic is found to be influenced significantly only above a minimum critical intensity of the electric field.
Spiking patterns of a hippocampus model in electric fields
Institute of Scientific and Technical Information of China (English)
Men Cong; Wang Jiang; Qin Ying-Mei; Wei Xi-Le; Che Yan-Qiu; Deng Bin
2011-01-01
We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective.Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study.The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity.It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field.Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude.These findings are qualitatively in accordance with the results of relevant experimental and numerical studies.It is implied that the external or endogenous electric field can modulate the neural code in the brain.Furthermore,it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy.
[Study on dewatering of activated sludge under applied electric field].
Ji, Xue-Yuan; Wang, Yi-Li; Feng, Jing
2012-12-01
For an electro-dewatering process of activated sludge (AS), the effect of pH and conductivity of AS, flocculation conditioning and operation factors of horizontal electric field (voltage magnitude, method of applying electric field and distance between plates) were investigated, and the corresponding optimum electro-dewatering conditions were also obtained. The results showed that the best electro-dewatering effect was achieved for AS without change of its pH value (6.93) and conductivity (1.46 mS x cm(-1)). CPAM conditioning could lead to the increase of 30%-40% in the dewatering rate and accelerate the dewatering process, whereas a slight increase in the electro-dewatering rate. The electro-dewatering rate for conditioned AS reached 83.12% during an electric field applied period of 60 minutes, while this rate for original AS could be 75.31% even the electric field applied period extended to 120 minutes. The delay of applying the electric field had an inhibition effect on the AS electro-dewatering rate. Moreover, the optimum conditions for AS electro-dewatering were followed: CPAM dose of 9 g x kg(-1), electric field strength of 600 V x m(-1), distance between the two plates of 40 mm, dehydration time of 60 minutes. Under above optimum conditions the AS electro-dewatering rate could approach to 85.33% and the moisture content in AS decreased from 99.30% to 95.15% accordingly.
Vacuum radiation induced by time dependent electric field
Directory of Open Access Journals (Sweden)
Bo Zhang
2017-04-01
Full Text Available Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.
Propagation of Magnetic Fields from Electrical Domestic Appliances
Orlova, K. N.; Gaidamak, M. A.; Borovikov, I. F.
2016-08-01
The article presents a research into propagation of magnetic fields from electrical domestic devices. A safe distance at which magnetic induction does not exceed the background level is determined for each type of devices. It is proved that there are two stages of increasing magnetic induction as the distance from the source increases. At the first stage magnetic induction rises and electromagnetic field is formed. At the second stage exponential decrease of magnetic field induction takes place. Mathematical regularities of propagation of magnetic field from electrical domestic devices are experimentally educed.
The chromatographic separation of particles using optical electric fields
DEFF Research Database (Denmark)
Javier Alvarez, Nicolas; Jeppesen, Claus; Yvind, Kresten
2013-01-01
We introduce a new field-flow fractionation (FFF) technique, whereby molecules are separated based on their differential interaction (dielectrophoresis (DEP)) with optical electric fields, i.e. electric fields with frequencies in the visible and near-infrared range. The results show that a parallel...... array of axially non-uniform optical fields yielding an attractive potential (positive-DEP-FFF) is advantageous for the separation of polymers, biomolecules, and nanoparticles over very short distances. Furthermore, positive-DEP-FFF yields superior selectivity and resolution compared to conventional...
Vacuum radiation induced by time dependent electric field
Zhang, Bo; Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian; Gu, Yu-qiu
2017-04-01
Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.
Ponderomotive Force in the Presence of Electric Fields
Khazanov, G. V.; Krivorutsky, E. N.
2013-01-01
This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces.
Low magnetic Johnson noise electric field plates for precision measurement
Rabey, I M; Hinds, E A; Sauer, B E
2016-01-01
We describe a parallel pair of high voltage electric field plates designed and constructed to minimise magnetic Johnson noise. They are formed by laminating glass substrates with commercially available polyimide (Kapton) tape, covered with a thin gold film. Tested in vacuum, the outgassing rate is less than $5\\times10^{-5}$ mbar.l/s. The plates have been operated at electric fields up to 8.3 kV/cm, when the leakage current is at most a few hundred pA. The design is discussed in the context of a molecular spin precession experiment to measure the permanent electric dipole moment of the electron.
Electric field and temperature effects in irradiated MOSFETs
Silveira, M. A. G.; Santos, R. B. B.; Leite, F. G.; Araújo, N. E.; Cirne, K. H.; Melo, M. A. A.; Rallo, A.; Aguiar, Vitor. A. P.; Aguirre, F.; Macchione, E. L. A.; Added, N.; Medina, N. H.
2016-07-01
Electronic devices exposed to ionizing radiation exhibit degradation on their electrical characteristics, which may compromise the functionality of the device. Understanding the physical phenomena responsible for radiation damage, which may be specific to a particular technology, it is of extreme importance to develop methods for testing and recovering the devices. The aim of this work is to check the influence of thermal annealing processes and electric field applied during irradiation of Metal Oxide Semiconductor Field Effect Transistors (MOSFET) in total ionizing dose experiments analyzing the changes in the electrical parameters in these devices
Electric Field-Responsive Mesoporous Suspensions: A Review
Directory of Open Access Journals (Sweden)
Seung Hyuk Kwon
2015-12-01
Full Text Available This paper briefly reviews the fabrication and electrorheological (ER characteristics of mesoporous materials and their nanocomposites with conducting polymers under an applied electric field when dispersed in an insulating liquid. Smart fluids of electrically-polarizable particles exhibit a reversible and tunable phase transition from a liquid-like to solid-like state in response to an external electric field of various strengths, and have potential applications in a variety of active control systems. The ER properties of these mesoporous suspensions are explained further according to their dielectric spectra in terms of the flow curve, dynamic moduli, and yield stress.
Static electric field enhancement in nanoscale structures
Lepetit, Bruno; Lemoine, Didier; Márquez-Mijares, Maykel
2016-08-01
We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.
Static electric field enhancement in nanoscale structures
Energy Technology Data Exchange (ETDEWEB)
Lepetit, Bruno, E-mail: bruno.lepetit@irsamc.ups-tlse.fr; Lemoine, Didier, E-mail: didier.lemoine@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Márquez-Mijares, Maykel, E-mail: mmarquez@instec.cu [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); Instituto Superior de Tecnologías y Ciencias Aplicadas, Avenida Salvador Allende 1110, Quinta de los Molinos, La Habana (Cuba)
2016-08-28
We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.
Report on Non-Contact DC Electric Field Sensors
Energy Technology Data Exchange (ETDEWEB)
Miles, R; Bond, T; Meyer, G
2009-06-16
This document reports on methods used to measure DC electrostatic fields in the range of 100 to 4000 V/m using a non-contact method. The project for which this report is written requires this capability. Non-contact measurements of DC fields is complicated by the effect of the accumulation of random space-charges near the sensors which interfere with the measurement of the field-of-interest and consequently, many forms of field measurements are either limited to AC measurements or use oscillating devices to create pseudo-AC fields. The intent of this document is to report on methods discussed in the literature for non-contact measurement of DC fields. Electric field meters report either the electric field expressed in volts per distance or the voltage measured with respect to a ground reference. Common commercial applications for measuring static (DC) electric fields include measurement of surface charge on materials near electronic equipment to prevent arcing which can destroy sensitive electronic components, measurement of the potential for lightning to strike buildings or other exposed assets, measurement of the electric fields under power lines to investigate potential health risks from exposure to EM fields and measurement of fields emanating from the brain for brain diagnostic purposes. Companies that make electric field sensors include Trek (Medina, NY), MKS Instruments, Boltek, Campbell Systems, Mission Instruments, Monroe Electronics, AlphaLab, Inc. and others. In addition to commercial vendors, there are research activities continuing in the MEMS and optical arenas to make compact devices using the principles applied to the larger commercial sensors.
Reversible electric-field control of magnetization at oxide interfaces
Cuellar, F. A.; Liu, Y. H.; Salafranca, J.; Nemes, N.; Iborra, E.; Sanchez-Santolino, G.; Varela, M.; Hernandez, M. Garcia; Freeland, J. W.; Zhernenkov, M.; Fitzsimmons, M. R.; Okamoto, S.; Pennycook, S. J.; Bibes, M.; Barthélémy, A.; Te Velthuis, S. G. E.; Sefrioui, Z.; Leon, C.; Santamaria, J.
2014-06-01
Electric-field control of magnetism has remained a major challenge which would greatly impact data storage technology. Although progress in this direction has been recently achieved, reversible magnetization switching by an electric field requires the assistance of a bias magnetic field. Here we take advantage of the novel electronic phenomena emerging at interfaces between correlated oxides and demonstrate reversible, voltage-driven magnetization switching without magnetic field. Sandwiching a non-superconducting cuprate between two manganese oxide layers, we find a novel form of magnetoelectric coupling arising from the orbital reconstruction at the interface between interfacial Mn spins and localized states in the CuO2 planes. This results in a ferromagnetic coupling between the manganite layers that can be controlled by a voltage. Consequently, magnetic tunnel junctions can be electrically toggled between two magnetization states, and the corresponding spin-dependent resistance states, in the absence of a magnetic field.
Electric field-induced softening of alkali silicate glasses
Energy Technology Data Exchange (ETDEWEB)
McLaren, C.; Heffner, W.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Tessarollo, R.; Raj, R. [Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)
2015-11-02
Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.
Electric field-induced softening of alkali silicate glasses
McLaren, C.; Heffner, W.; Tessarollo, R.; Raj, R.; Jain, H.
2015-11-01
Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.
Rovibrational spectra of diatomic molecules in strong electric fields
Energy Technology Data Exchange (ETDEWEB)
Gonzalez-Ferez, R; Schmelcher, P [Departamento de Fisica Moderna and Instituto ' Carlos I' de Fisica Teorica y Computacional, Facultad de Ciencias, Universidad de Granada, E-18071 Granada (Spain); Theoretische Chemie, Physikalisch-Chemisches Institut, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany); Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, D-69120 Heidelberg (Germany)
2005-01-01
We investigate the effects of a strong static electric field on the rovibrational spectra of diatomic heteronuclear molecules in a {sup 1}{sigma}{sup +} electronic ground state. Using a hybrid computational technique combining discretization and basis set methods the full rovibrational equation of motion is solved. As a prototype for our computations we take the carbon monoxide molecule. For experimentally accessible field strengths we observe that while low-lying states are not significantly affected by the field, for highly excited states strong orientation and hybridization are achieved. We propose an effective rotor Hamiltonian, including the main properties of each vibrational state, to describe the influence of the electric field on the rovibrational spectra of a molecular system with a small coupling between its rotational and vibrational motions. This effective rotor approach goes significantly beyond the rigid rotor approach and is able to describe the effect of the electric field for highly excited states.
Rydberg-Stark states in oscillating electric fields
Zhelyazkova, V
2015-01-01
Experimental and theoretical studies of the effects of weak radio-frequency electric fields on Rydberg-Stark states with electric dipole moments as large as 10000 D are reported. High-resolution laser spectroscopic studies of Rydberg states with principal quantum number $n=52$ and $53$ were performed in pulsed supersonic beams of metastable helium with the excited atoms detected by pulsed electric field ionisation. Experiments were carried out in the presence of sinusoidally oscillating electric fields with frequencies of 20~MHz, amplitudes of up to 120~mV/cm, and dc offsets of up to 4.4~V/cm. In weak fields the experimentally recorded spectra are in excellent agreement with the results of calculations carried out using Floquet methods to account for electric dipole couplings in the oscillating fields. This highlights the validity of these techniques for the accurate calculation of the Stark energy level structure in such fields, and the limitations of the calculations in stronger fields where $n-$mixing and ...
Rydberg-Stark states in oscillating electric fields
Zhelyazkova, V.; Hogan, S. D.
2015-12-01
Experimental and theoretical studies of the effects of weak radio-frequency electric fields on Rydberg-Stark states with electric dipole moments as large as 10,000 D are reported. High-resolution laser spectroscopic studies of Rydberg states with principal quantum number n = 52 and 53 were performed in pulsed supersonic beams of metastable helium with the excited atoms detected by pulsed electric field ionisation. Experiments were carried out in the presence of sinusoidally oscillating electric fields with frequencies of 20 MHz, amplitudes of up to 120 mV/cm, and dc offsets of up to 4.4 V/cm. In weak fields, the experimentally recorded spectra are in excellent agreement with the results of calculations carried out using Floquet methods to account for electric dipole couplings in the oscillating fields. This highlights the validity of these techniques for the accurate calculation of the Stark energy level structure in such fields, and the limitations of the calculations in stronger fields where n-mixing and higher order contributions become important.
New Method for Solving Inductive Electric Fields in the Ionosphere
Vanhamäki, H.
2005-12-01
We present a new method for calculating inductive electric fields in the ionosphere. It is well established that on large scales the ionospheric electric field is a potential field. This is understandable, since the temporal variations of large scale current systems are generally quite slow, in the timescales of several minutes, so inductive effects should be small. However, studies of Alfven wave reflection have indicated that in some situations inductive phenomena could well play a significant role in the reflection process, and thus modify the nature of ionosphere-magnetosphere coupling. The input to our calculation method are the time series of the potential part of the ionospheric electric field together with the Hall and Pedersen conductances. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfven wave reflection from uniformly conducting ionosphere.
Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro
We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization
DEFF Research Database (Denmark)
Opitz, Alexander; Falchier, Arnaud; Yan, Chao-Gan
2016-01-01
Transcranial electric stimulation (TES) is an emerging technique, developed to non-invasively modulate brain function. However, the spatiotemporal distribution of the intracranial electric fields induced by TES remains poorly understood. In particular, it is unclear how much current actually reac...
Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro
2011-01-01
We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme
Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro
2011-01-01
We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme
Limiting electric fields of HVDC overhead power lines.
Leitgeb, N
2014-05-01
As a consequence of the increased use of renewable energy and the now long distances between energy generation and consumption, in Europe, electric power transfer by high-voltage (HV) direct current (DC) overhead power lines gains increasing importance. Thousands of kilometers of them are going to be built within the next years. However, existing guidelines and regulations do not yet contain recommendations to limit static electric fields, which are one of the most important criteria for HVDC overhead power lines in terms of tower design, span width and ground clearance. Based on theoretical and experimental data, in this article, static electric fields associated with adverse health effects are analysed and various criteria are derived for limiting static electric field strengths.
Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields
Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)
2001-01-01
Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.
High school students' representations and understandings of electric fields
Cao, Ying; Brizuela, Bárbara M.
2016-12-01
This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields postinstruction as indicated by students' performance on textbook-style questions. It has, however, inadequately captured student ideas expressed in other situations yet informative to educational research. In this study, we explore students' ideas of electric fields preinstruction as shown by students' representations produced in open-ended activities. 92 participant students completed a worksheet that involved drawing comic strips about electric charges as characters of a cartoon series. Three students who had spontaneously produced arrow diagrams were interviewed individually after class. We identified nine ideas related to electric fields that these three students spontaneously leveraged in the comic strip activity. In this paper, we describe in detail each idea and its situated context. As most research in the literature has understood students as having relatively fixed conceptions and mostly identified divergences in those conceptions from canonical targets, this study shows students' reasoning to be more variable in particular moments, and that variability includes common sense resources that can be productive for learning about electric fields.
Consistency restrictions on maximal electric-field strength in quantum field theory.
Gavrilov, S P; Gitman, D M
2008-09-26
Quantum field theory with an external background can be considered as a consistent model only if backreaction is relatively small with respect to the background. To find the corresponding consistency restrictions on an external electric field and its duration in QED and QCD, we analyze the mean-energy density of quantized fields for an arbitrary constant electric field E, acting during a large but finite time T. Using the corresponding asymptotics with respect to the dimensionless parameter eET2, one can see that the leading contributions to the energy are due to the creation of particles by the electric field. Assuming that these contributions are small in comparison with the energy density of the electric background, we establish the above-mentioned restrictions, which determine, in fact, the time scales from above of depletion of an electric field due to the backreaction.
Choi, Bup Kyung; Oh, Tong In; Sajib, Saurav Zk; Kim, Jin Woong; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je
2017-04-01
To realistically map the electric fields of biological tissues using a diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) method to estimate tissue response during electrical stimulation. Imaging experiments were performed using chunks of bovine muscle. Two silver wire electrodes were positioned inside the muscle tissue for electrical stimulation. Electric pulses were applied with a 100-V amplitude and 100-μs width using a voltage stimulator. During electrical stimulation, we collected DT-MREIT data from a 3T magnetic resonance imaging scanner. We adopted the projected current density method to calculate the electric field. Based on the relation between the water diffusion tensor and the conductivity tensor, we computed the position-dependent scale factor using the measured magnetic flux density data. Then, a final conductivity tensor map was reconstructed using the multiplication of the water diffusion tensor and the scale factor. The current density images from DT-MREIT data represent the internal current flows that exist not only in the electrodes but also in surrounding regions. The reconstructed electric filed map from our anisotropic conductivity tensor with the projected current density shows coverage that is more than 2 times as wide, and higher signals in both the electrodes and surrounding tissues, than the previous isotropic method owing to the consideration of tissue anisotropy. An electric field map obtained by an anisotropic reconstruction method showed different patterns from the results of the previous isotropic reconstruction method. Since accurate electric field mapping is important to correctly estimate the coverage of the electrical treatment, future studies should include more rigorous validations of the new method through in vivo and in situ experiments.
2017-01-01
Purpose To realistically map the electric fields of biological tissues using a diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) method to estimate tissue response during electrical stimulation. Methods Imaging experiments were performed using chunks of bovine muscle. Two silver wire electrodes were positioned inside the muscle tissue for electrical stimulation. Electric pulses were applied with a 100-V amplitude and 100-μs width using a voltage stimulator. During electrical stimulation, we collected DT-MREIT data from a 3T magnetic resonance imaging scanner. We adopted the projected current density method to calculate the electric field. Based on the relation between the water diffusion tensor and the conductivity tensor, we computed the position-dependent scale factor using the measured magnetic flux density data. Then, a final conductivity tensor map was reconstructed using the multiplication of the water diffusion tensor and the scale factor. Results The current density images from DT-MREIT data represent the internal current flows that exist not only in the electrodes but also in surrounding regions. The reconstructed electric filed map from our anisotropic conductivity tensor with the projected current density shows coverage that is more than 2 times as wide, and higher signals in both the electrodes and surrounding tissues, than the previous isotropic method owing to the consideration of tissue anisotropy. Conclusions An electric field map obtained by an anisotropic reconstruction method showed different patterns from the results of the previous isotropic reconstruction method. Since accurate electric field mapping is important to correctly estimate the coverage of the electrical treatment, future studies should include more rigorous validations of the new method through in vivo and in situ experiments. PMID:28446015
Effect of Electric Field on Outwardly Propagating Spherical Flame
Mannaa, Ossama
2012-06-01
The thesis comprises effects of electric fields on a fundamental study of spherical premixed flame propagation.Outwardly-propagating spherical laminar premixed flames have been investigated in a constant volume combustion vessel by applying au uni-directional electric potential.Direct photography and schlieren techniques have been adopted and captured images were analyzed through image processing. Unstretched laminar burning velocities under the influence of electric fields and their associated Markstein length scales have been determined from outwardly propagating spherical flame at a constant pressure. Methane and propane fuels have been tested to assess the effect of electric fields on the differential diffusion of the two fuels.The effects of varying equivalence ratios and applied voltages have been investigated, while the frequency of AC was fixed at 1 KHz. Directional propagating characteristics were analyzed to identify the electric filed effect. The flame morphology varied appreciably under the influence of electric fields which in turn affected the burning rate of mixtures.The flame front was found to propagate much faster toward to the electrode at which the electric fields were supplied while the flame speeds in the other direction were minimally influenced. When the voltage was above 7 KV the combustion is markedly enhanced in the downward direction since intense turbulence is generated and as a result the mixing process or rather the heat and mass transfer within the flame front will be enhanced.The combustion pressure for the cases with electric fields increased rapidly during the initial stage of combustion and was relatively higher since the flame front was lengthened in the downward direction.
Electric field mapping inside metallized film capacitors
DEFF Research Database (Denmark)
Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld
2015-01-01
and durability and serves as verification that failure- and degradation mechanisms remain the same at different stress levels during accelerated testing. In this work we have used Kelvin probe force microscopy (KPFM) to analyze metallized film capacitors with the purpose of determining the degradation mechanism......(s) they suffered from accelerated testing. We have prepared film capacitors for analysis by micro-sectioning and verified the quality of the preparation procedure using optical and atomic force microscopy. The potential distribution in the layer structure (alternating 7 µm thick dielectric and 50-100 nm thick...... of the metallization stripes had lost contact to the end-spray. Thus, it is shown that the surface electric potential distributions on micro-sectioned film capacitors can be obtained through KPFM analysis. We have, from KPFM measurements, shown that the degraded capacitors under investigation had suffered from...
High electric field phenomena in insulation
Laghari, J. R.; Sarjeant, W. J.
1989-01-01
The present study extends previous work to include electron radiation-induced changes in monoisopropyl biphenyl (MIPB)-impregnated polypropylene film as well as the effects of neutron/gamma radiation on dry polypropylene films. Effects that were quite similar were induced by both electron and neutron radiation on the properties of interest of the polypropylene films. Impregnation of the film with MIPB had a mitigatory effect on the degradation of the properties. This report also contains the results of a simultaneous electrical and thermal aging study of a capacitor-grade polypropylene film. The data obtained in this study was fitted to models that will enable realistic prediction of lifetimes under operating conditions.
Elastic constant of Dendrobium protoplasts in AC electric fields
Directory of Open Access Journals (Sweden)
Pikul Wanichapichart
2002-11-01
Full Text Available This work reports elongation of Dendrobium protoplasts in an ac electric field between two cylindrical electrodes. A protoplast firstly was translated towards an electrode by dielectrophoretic force in 17 kV.m-1 field strength at 1 MHz, and secondly it was elongated due to an interaction between an induced electric dipole (μ and the electric field (E. Protoplast elongation was observed by varying both the field strength at 30, 45, 60, and 85 kV.m-1 and field frequency at 0.5, 1, 5, and 10 MHz. For a given field frequency and field strength, a parameter a/b (major/minor axis was measured as the protoplast elongation.Two-step elongation and restoration phases were observed. The former was completed within 2 minutes of field exposure, and the latter was completed within 15 seconds regardless of the field exposure time between 3 and 20 minutes. The evidence of a complete restoration indicated that the elasticity of the protoplast membrane obeyed Hooke’s law. This study also found that elastic constant k of the membrane varied non-linearly with the field strength. It was found to be from 0.04 to 0.08 mN.m-1, dependent on the field frequency.
Wetting of sessile water drop under an external electrical field
Vancauwenberghe, Valerie; di Marco, Paolo; Brutin, David; Amu Collaboration; Unipi Collaboration
2013-11-01
The enhancement of heat and mass transfer using a static electric field is an interesting process for industrial applications, due to its low energy consumption and potentially high level of evaporation rate enhancement. However, to date, this phenomenon is still not understood in the context of the evaporation of sessile drops. We previously synthesized the state of the art concerning the effect of an electric field on sessile drops with a focus on the change of contact angle and shape and the influence of the evaporation rate [1]. We present here the preliminary results of an new experiment set-up. The novelty of the set-up is the drop injection from the bottom that allows to generate safety the droplet under the electrostatic field. The evaporation at room temperature of water drops having three different volumes has been investigated under an electric field up to 10.5 kV/cm. The time evolutions of the contact angles, volumes and diameters have been analysed. As reported in the literature, the drop elongate along the direction of the electric field. Despite the hysteresis effect of the contact angle, the receding contact angle increases with the strength of the electric field. This is clearly observable for the small drops for which the gravity effect can be neglected.
Premixed combustion under electric field in a constant volume chamber
Cha, Min Suk
2012-12-01
The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.
Effects of non-perturbatively improved dynamical fermions in QCD at fixed lattice spacing
Allton, C R; Bowler, K C; Garden, J; Hart, A; Hepburn, D; Irving, A C; Joó, B; Kenway, R D; Maynard, C M; McNeile, C; Michael, C; Pickles, S M; Sexton, J C; Sharkey, K J; Sroczynski, Z; Talevi, M; Teper, M; Wittig, H
2002-01-01
We present results for the static inter-quark potential, lightest glueballs, light hadron spectrum and topological susceptibility using a non-perturbatively improved action on a $16^3\\times 32$ lattice at a set of values of the bare gauge coupling and bare dynamical quark mass chosen to keep the lattice size fixed in physical units ($\\sim 1.7$ fm). By comparing these measurements with a matched quenched ensemble, we study the effects due to two degenerate flavours of dynamical quarks. With the greater control over residual lattice spacing effects which these methods afford, we find some evidence of charge screening and some minor effects on the light hadron spectrum over the range of quark masses studied ($M_{PS}/M_{V}\\ge0.58$). More substantial differences between quenched and unquenched simulations are observed in measurements of topological quantities.
Non-perturbative running of quark masses in three-flavour QCD
Campos, Isabel; Pena, Carlos; Preti, David; Ramos, Alberto; Vladikas, Anastassios
2016-01-01
We present our preliminary results for the computation of the non-perturbative running of renormalized quark masses in $N_f = 3$ QCD, between the electroweak and hadronic scales, using standard finite-size scaling techniques. The computation is carried out to very high precision, using massless $\\mathcal{O}(a)$-improved Wilson quarks. Following the strategy adopted by the ALPHA Collaboration for the running coupling, different schemes are used above and below a scale $\\mu_0 \\sim m_b$, which differ by using either the Schr\\"odinger Functional or Gradient Flow renormalized coupling. We discuss our results for the running in both regions, and the procedure to match the two schemes.
The B-meson mass splitting from non-perturbative quenched lattice QCD
Grozin, A G; Marquard, P; Meyer, H B; Piclum, J H; Sommer, R; Steinhauser, M
2007-01-01
We perform the non-perturbative (quenched) renormalization of the chromo-magnetic operator in Heavy Quark Effective Theory and its three-loop matching to QCD. At order 1/m of the expansion, the operator is responsible for the mass splitting between the pseudoscalar and vector B-mesons. These new computed factors are affected by an uncertainty negligible in comparison to the known bare matrix element of the operator between B-states. Furthermore, they push the quenched determination of the spin splitting for the Bs-meson much closer to its experimental value than the previous perturbatively renormalized computations. The renormalization factor for three commonly used heavy quark actions and the Wilson gauge action and useful parametrizations of the matching coefficient are provided.
Cichy, Krzysztof; Korcyl, Piotr
2016-01-01
Working in a quenched setup with Wilson twisted mass valence fermions, we explore the possibility to compute non-perturbatively the step scaling function using the coordinate (X-space) renormalization scheme. This scheme has the advantage of being on-shell and gauge invariant. The step scaling method allows us to calculate the running of the renormalization constants of quark bilinear operators. We describe here the details of this calculation. The aim of this exploratory study is to identify the feasibility of the X-space scheme when used in small volume simulations required by the step scaling technique. Eventually, we translate our final results to the continuum MSbar scheme and compare against four-loop analytic formulae finding satisfactory agreement.
Non-perturbative QCD: renormalization, O(a)-improvement and matching to Heavy Quark Effective Theory
Sommer, R
2006-01-01
We give an introduction to three topics in lattice gauge theory: I. The Schroedinger Functional and O(a) improvement. O(a) improvement has been reviewed several times. Here we focus on explaining the basic ideas in detail and then proceed directly to an overview of the literature and our personal assessment of what has been achieved and what is missing. II. The computation of the running coupling, running quark masses and the extraction of the renormalization group invariants. We focus on the basic strategy and on the large effort that has been invested in understanding the continuum limit. We point out what remains to be done. III. Non-perturbative Heavy Quark Effective Theory. Since the literature on this subject is still rather sparse, we go beyond the basic ideas and discuss in some detail how the theory works in principle and in practice.
Disentangling the timescales behind the non-perturbative heavy quark potential
Burnier, Yannis
2012-01-01
The static part of the heavy quark potential has been shown to be closely related to the spectrum of the rectangular Wilson loop. In particular the lowest lying positive frequency peak encodes the late time evolution of the two-body system, characterized by a complex potential. While initial studies assumed a perfect separation of early and late time physics, where a simple Lorentian (Breit-Wigner) shape suffices to describe the spectral peak, we argue that scale decoupling in general is not complete. Thus early time, i.e. non-potential effects, significantly modify the shape of the lowest peak. We derive on general grounds an improved peak distribution that reflects this fact. Application of the improved fit to non-perturbative lattice QCD spectra now yields a potential that is compatible with a transition to a deconfined screening plasma.
Non-Perturbative, Unitary Quantum-Particle Scattering Amplitudes from Three-Particle Equations
Energy Technology Data Exchange (ETDEWEB)
Lindesay, James V
2002-03-19
We here use our non-perturbative, cluster decomposable relativistic scattering formalism to calculate photon-spinor scattering, including the related particle-antiparticle annihilation amplitude. We start from a three-body system in which the unitary pair interactions contain the kinematic possibility of single quantum exchange and the symmetry properties needed to identify and substitute antiparticles for particles. We extract from it unitary two-particle amplitude for quantum-particle scattering. We verify that we have done this correctly by showing that our calculated photon-spinor amplitude reduces in the weak coupling limit to the usual lowest order, manifestly covariant (QED) result with the correct normalization. That we are able to successfully do this directly demonstrates that renormalizability need not be a fundamental requirement for all physically viable models.
A Non-Perturbative, Finite Particle Number Approach to Relativistic Scattering Theory
Energy Technology Data Exchange (ETDEWEB)
Lindesay, James V
2001-05-11
We present integral equations for the scattering amplitudes of three scalar particles, using the Faddeev channel decomposition, which can be readily extended to any finite number of particles of any helicity. The solution of these equations, which have been demonstrated to be calculable, provide a non-perturbative way of obtaining relativistic scattering amplitudes for any finite number of particles that are Lorentz invariant, unitary, cluster decomposable and reduce unambiguously in the non-relativistic limit to the non-relativistic Faddeev equations. The aim of this program is to develop equations which explicitly depend upon physically observable input variables, and do not require ''renormalization'' or ''dressing'' of these parameters to connect them to the boundary states.
Non-perturbative QCD. Renormalization, O(a)-improvement and matching to heavy quark effective theory
Energy Technology Data Exchange (ETDEWEB)
Sommer, R.
2006-11-15
We give an introduction to three topics in lattice gauge theory: I. The Schroedinger Functional and O(a) improvement. O(a) improvement has been reviewed several times. Here we focus on explaining the basic ideas in detail and then proceed directly to an overview of the literature and our personal assessment of what has been achieved and what is missing. II. The computation of the running coupling, running quark masses and the extraction of the renormalization group invariants. We focus on the basic strategy and on the large effort that has been invested in understanding the continuum limit. We point out what remains to be done. III. Non-perturbative Heavy Quark Effective Theory. Since the literature on this subject is still rather sparse, we go beyond the basic ideas and discuss in some detail how the theory works in principle and in practice. (orig.)
Cichy, Krzysztof; Jansen, Karl; Korcyl, Piotr
2016-12-01
Working in a quenched setup with Wilson twisted mass valence fermions, we explore the possibility to compute non-perturbatively the step scaling function using the coordinate (X-space) renormalization scheme. This scheme has the advantage of being on-shell and gauge invariant. The step scaling method allows us to calculate the running of the renormalization constants of quark bilinear operators. We describe here the details of this calculation. The aim of this exploratory study is to identify the feasibility of the X-space scheme when used in small volume simulations required by the step scaling technique. Eventually, we translate our final results to the continuum MS ‾ scheme and compare against four-loop analytic formulae finding satisfactory agreement.
Anagnostopoulos, Konstantinos N; Nishimura, Jun
2012-01-01
The IKKT or IIB matrix model has been postulated to be a non perturbative definition of superstring theory. It has the attractive feature that spacetime is dynamically generated, which makes possible the scenario of dynamical compactification of extra dimensions, which in the Euclidean model manifests by spontaneously breaking the SO(10) rotational invariance (SSB). In this work we study using Monte Carlo simulations the 6 dimensional version of the Euclidean IIB matrix model. Simulations are found to be plagued by a strong complex action problem and the factorization method is used for effective sampling and computing expectation values of the extent of spacetime in various dimensions. Our results are consistent with calculations using the Gaussian Expansion method which predict SSB to SO(3) symmetric vacua, a finite universal extent of the compactified dimensions and finite spacetime volume.
Production of pulsed electric fields using capacitively coupled electrodes
Kendall, B. R. F.; Schwab, F. A. S.
1980-01-01
It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 100-1000 V/cm extending over several centimeters. Scaling to larger physical dimensions is straightforward.
Using Gravitational Analogies to Introduce Elementary Electrical Field Theory Concepts
Saeli, Susan; MacIsaac, Dan
2007-01-01
Since electrical field concepts are usually unfamiliar, abstract, and difficult to visualize, conceptual analogies from familiar gravitational phenomena are valuable for teaching. Such analogies emphasize the underlying continuity of field concepts in physics and support the spiral development of student understanding. We find the following four…
Noncommuting Electric Fields and Algebraic Consistency in Noncommutative Gauge theories
Banerjee, R
2003-01-01
We show that noncommuting electric fields occur naturally in noncommutative gauge theories. Using this noncommutativity, which is field dependent, and a hamiltonian generalisation of the Seiberg-Witten Map, the algebraic consistency in the lagrangian and hamiltonian formulations of these theories, is established. The stability of the Poisson algebra, under this generalised map, is studied.
Electric-field effect in partially deoxygenated YBCO thin films
Energy Technology Data Exchange (ETDEWEB)
Kula, W. (Dept. of Electrical Engineering and Lab. for Laser Energetics, Univ. of Rochester, NY (United States) Inst. of Physics, Polish Academy of Sciences, Warszawa (Poland)); Sobolewski, R. (Dept. of Electrical Engineering and Lab. for Laser Energetics, Univ. of Rochester, NY (United States) Inst. of Physics, Polish Academy of Sciences, Warszawa (Poland))
1994-02-01
We report our studies on the electric-field effect in partially oxygen-depleted YBa[sub 2]Cu[sub 3]O[sub y] (YBCO) thin-film test structures fabricated by a laser-writing patterning technique. Our preliminary results indicate substantial, field-induced changes of the sample critical current. (orig.)
Asymmetry of Neoclassical Transport by Dipole Electric Field
Institute of Scientific and Technical Information of China (English)
王中天; 王龙
2004-01-01
Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport. For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity.
Effects of pulsed electric field on ULQ and RFP plasmas
Energy Technology Data Exchange (ETDEWEB)
Watanabe, M. [Iwate Univ., Morioka (Japan). Faculty of Engineering; Saito, K.; Suzuki, T. [and others
1997-12-31
Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)
Time Evolution of Electric Fields in CDMS Detectors
Leman, S W; Brink, P L; Cabrera, B; Chagani, H; Cherry, M; Cushman, P; Silva, E Do Couto E; Doughty, T; Figueroa-Feliciano, E; Mandic, V; McCarthy, K A; Mirabolfathi, N; Pyle, M; Reisetter, A; Resch, R; Sadoulet, B; Serfass, B; Sundqvist, K M; Tomada, A; Young, B A; Zhang, J
2011-01-01
The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3" diameter x 1" thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors, the later providing a $\\sim$1 V cm$^{-1}$ electric field in the detector bulk. Cumulative radiation exposure which creates $\\sim 200\\times 10^6$ electron-hole pairs is sufficient to produce a comparable reverse field in the detector thereby degrading the ionization channel performance. To study this, the existing CDMS detector Monte Carlo has been modified to allow for an event by event evolution of the bulk electric field, in three spatial dimensions. Our most resent results and interpretation are discussed.
Electro-optic probe measurements of electric fields in plasmas
Nishiura, M.; Yoshida, Z.; Mushiake, T.; Kawazura, Y.; Osawa, R.; Fujinami, K.; Yano, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.
2017-02-01
The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.
Directory of Open Access Journals (Sweden)
R. R. Ilma
2012-01-01
Full Text Available A correlation of the ionospheric electric field and the time derivative of the magnetic field was noticed over thirty years ago and has yet to be explained. Here we report on another set of examples during the superstorm of November 2004. The electric field in the equatorial ionosphere, measured with the Jicamarca incoherent scatter radar, exhibited a 3 mV/m electric field pulse that was not seen in the interplanetary medium. It was, however, accompanied by a correlation with the time derivative of the magnetic field measured at two points in Peru. Our inclination was to assume that the field was inductive. However, the time scale of the pulse was too short for the magnetic field to penetrate the crust of the Earth. This means that the area threaded by ∂B/∂t was too small to create the observed electric field by induction. We suggest that the effect was caused by a modulation of the ring current location relative to the Earth due to the electric field. This electric field is required, as the magnetic field lines are considered frozen into the plasma in the magnetosphere. The closer location of the ring current to the Earth in turn increased the magnetic field at the surface.
Skin Rejuvenation with Non-Invasive Pulsed Electric Fields
Golberg, Alexander; Khan, Saiqa; Belov, Vasily; Quinn, Kyle P.; Albadawi, Hassan; Felix Broelsch, G.; Watkins, Michael T.; Georgakoudi, Irene; Papisov, Mikhail; Mihm, Martin C., Jr.; Austen, William G., Jr.; Yarmush, Martin L.
2015-05-01
Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases.
Vapor-liquid equilibrium in electric field gradients.
Samin, Sela; Tsori, Yoav
2011-01-13
We investigate the vapor-liquid coexistence of polar and nonpolar fluids in the presence of a nonuniform electric field. We find that a large enough electric field can nucleate a gas bubble from the liquid phase or a liquid droplet from the vapor phase. The surface tension of the vapor-liquid interface is determined within squared-gradient theory. When the surface potential (charge) is controlled, the surface tension increases (decreases) compared to the zero-field interface. The effect of the electric field on the fluid phase diagram depends strongly on the constitutive relation for the dielectric constant. Finally, we show that gas bubbles can be nucleated far from the bounding surfaces.
Pulsed electric field reduces the permeability of potato cell wall.
Galindo, Federico Gómez; Vernier, P Thomas; Dejmek, Petr; Vicente, António; Gundersen, Martin A
2008-05-01
The effect of the application of pulsed electric fields to potato tissue on the diffusion of the fluorescent dye FM1-43 through the cell wall was studied. Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with one 1 ms rectangular pulse, before application of FM1-43 and microscopic examination. Our results show a slower diffusion of FM1-43 in the electropulsed tissue when compared with that in the non-pulsed tissue, suggesting that the electric field decreased the cell wall permeability. This is a fast response that is already detected within 30 s after the delivery of the electric field. This response was mimicked by exogenous H2O2 and blocked by sodium azide, an inhibitor of the production of H2O2 by peroxidases. (c) 2007 Wiley-Liss, Inc.
Effect of Electric Field on Conductivity and Vickers Hardness of an Al-Li Alloy
Liu, Bing; Chen, Da-Rong; Chen, Zheng; Wang, Yong-Xin; Li, Xiao-Ling
2003-11-01
Static electric fields were applied on an aluminium-lithium alloy during solution treatment. The conductivity and Vickers hardness of the quenched Al-Li alloy is changed with the effect of electric field. The Vickers hardness increases with the applied electric field for a certain solutionizing time but decreases with the time under an electric field. In the absence of the electric field, the Vickers hardness and the conductivity increase synchronously, while reversed after electric field treatment. Positive and negative electric fields had the similar effect. The change of the local electron density in alloy caused by electric field is presented to explain the effect.
Effect of Electric Field on Conductivity and Vickers Hardness of an A1-Li Alloy
Institute of Scientific and Technical Information of China (English)
刘兵; 陈大融; 陈铮; 王永欣; 李晓玲
2003-01-01
Static electric fields were applied on an aluminium-lithium alloy during solution treatment.The conductivity and Vickers hardness of the quenched Al-Li alloy is changed with the effect of electric field.The Vickers hardness increases with the applied electric field for a certain solutionizing time but decreases with the time under an electric field.In the absence of the electric field,the Vickers hardness and the conductivity increase synchronously,while reversed after electric field treatment.Positive and negative electric fields had the similar effect.The change of the local electron density in alloy caused by electric field is presented to explain the effect.
Coherent anti-Stokes Raman scattering under electric field stimulation
Capitaine, Erwan; Ould Moussa, Nawel; Louot, Christophe; Lefort, Claire; Pagnoux, Dominique; Duclère, Jean-René; Kaneyasu, Junya F.; Kano, Hideaki; Duponchel, Ludovic; Couderc, Vincent; Leproux, Philippe
2016-12-01
We introduce an experiment using electro-CARS, an electro-optical method based on the combination of ultrabroadband multiplex coherent anti-Stokes Raman scattering (M-CARS) spectroscopy and electric field stimulation. We demonstrate that this method can effectively discriminate the resonant CARS signal from the nonresonant background owing to a phenomenon of molecular orientation in the sample medium. Such molecular orientation is intrinsically related to the induction of an electric dipole moment by the applied static electric field. Evidence of the electro-CARS effect is obtained with a solution of n -alkanes (CnH2 n +2 , 15 ≤n ≤40 ), for which an enhancement of the CARS signal-to-noise ratio is achieved in the case of CH2 and CH3 symmetric/asymmetric stretching vibrations. Additionally, an electric-field-induced second-harmonic generation experiment is performed in order to corroborate the orientational organization of molecules due to the electric field excitation. Finally, we use a simple mathematical approach to compare the vibrational information extracted from electro-CARS measurements with spontaneous Raman data and to highlight the impact of electric stimulation on the vibrational signal.
Relationship between ionospheric electric fields and magnetic activity indices
Shirapov, D. Sh.
2012-02-01
The relations between electric fields in the daytime and nighttime sectors of the polar ionosphere and magnetic activity indices of auroral region (AL) and northern polar cap (PCN) are studied. It is found that the above relations do exist and are described by: a) equations U {pc/(1)} (kV) = 27.62 + 21.43PCN with a correlation coefficient R = 0.87 and U {pc/(1)} (kV) = 4.06 + 49.21PCN - 6.24 PCN2 between the difference in the electric potentials across the polar cap in the daytime sector U {pc/(1)} and PCN and b) regression equation U {pc/(2)} (kV) = 23.33 + 0.08|AL| with R = 0.86 between the difference in the electric potentials across the polar cap in the nighttime sector U {pc/(2)} and |AL|. It is shown that: a) it is possible to use the AL and PCN indices for real-time diagnostics of instantaneous values of the electric fields in the daytime and nighttime sectors of the polar ionosphere in the process of a substorm development; b) at the expansion phase of a substorm, due to calibration of PCN values by the values of the solar wind electric field E sw, the PCN index does not feel the contribution of the western electrojet and, accordingly, the contribution of the nighttime ionospheric electric field U {pc/(2)}, governed by the reconnection in the magnetospheric tail.
Manipulation of red blood cells with electric field
Saboonchi, Hossain; Esmaeeli, Asghar
2009-11-01
Manipulation of bioparticles and macromolecules is the central task in many biological and biotechnological processes. The current methods for physical manipulation takes advantage of different forces such as acoustic, centrifugal, magnetic, electromagnetic, and electric forces, as well as using optical tweezers or filtration. Among all these methods, however, the electrical forces are particularly attractive because of their favorable scale up with the system size which makes them well-suited for miniaturization. Currently the electric field is used for transportation, poration, fusion, rotation, and separation of biological cells. The aim of the current research is to gain fundamental understanding of the effect of electric field on the human red blood cells (RBCs) using direct numerical simulation. A front tracking/finite difference technique is used to solve the fluid flow and electric field equations, where the fluid in the cell and the blood (plasma) is modeled as Newtonian and incompressible, and the interface separating the two is treated as an elastic membrane. The behavior of RBCs is investigated as a function of the controlling parameters of the problem such as the strength of the electric field.
Modeling of electric field distribution in tissues during electroporation.
Corovic, Selma; Lackovic, Igor; Sustaric, Primoz; Sustar, Tomaz; Rodic, Tomaz; Miklavcic, Damijan
2013-02-21
Electroporation based therapies and treatments (e.g. electrochemotherapy, gene electrotransfer for gene therapy and DNA vaccination, tissue ablation with irreversible electroporation and transdermal drug delivery) require a precise prediction of the therapy or treatment outcome by a personalized treatment planning procedure. Numerical modeling of local electric field distribution within electroporated tissues has become an important tool in treatment planning procedure in both clinical and experimental settings. Recent studies have reported that the uncertainties in electrical properties (i.e. electric conductivity of the treated tissues and the rate of increase in electric conductivity due to electroporation) predefined in numerical models have large effect on electroporation based therapy and treatment effectiveness. The aim of our study was to investigate whether the increase in electric conductivity of tissues needs to be taken into account when modeling tissue response to the electroporation pulses and how it affects the local electric distribution within electroporated tissues. We built 3D numerical models for single tissue (one type of tissue, e.g. liver) and composite tissue (several types of tissues, e.g. subcutaneous tumor). Our computer simulations were performed by using three different modeling approaches that are based on finite element method: inverse analysis, nonlinear parametric and sequential analysis. We compared linear (i.e. tissue conductivity is constant) model and non-linear (i.e. tissue conductivity is electric field dependent) model. By calculating goodness of fit measure we compared the results of our numerical simulations to the results of in vivo measurements. The results of our study show that the nonlinear models (i.e. tissue conductivity is electric field dependent: σ(E)) fit experimental data better than linear models (i.e. tissue conductivity is constant). This was found for both single tissue and composite tissue. Our results of
Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C
2017-01-01
Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.4 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.89) and depth (r = 0.84) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials. DOI: http://dx.doi.org/10.7554/eLife.18834.001 PMID:28169833
Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C
2017-02-07
Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.4 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.89) and depth (r = 0.84) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.
Numerical simulation of electromagnetic and flow fields of TiAI melt under electric field
Institute of Scientific and Technical Information of China (English)
Zhang Yong; Ding Hongsheng; Jiang Sanyong; Chen Ruirun; Guo Jingjie
2010-01-01
This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAI melt under two electric fields. FEM (Finite Element Method) and APDL (ANSYS Parametric Design Language) were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth) under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAI melt to flow stronger than what the sinusoidal electric field does.
Water-methanol separation with carbon nanotubes and electric fields
Winarto, Affa; Takaiwa, Daisuke; Yamamoto, Eiji; Yasuoka, Kenji
2015-07-01
Methanol is used in various applications, such as fuel for transportation vehicles, fuel cells, and in chemical industrial processes. Conventionally, separation of methanol from aqueous solution is by distillation. However, this method consumes a large amount of energy; hence development of a new method is needed. In this work, molecular dynamics simulations are performed to investigate the effect of an electric field on water-methanol separation by carbon nanotubes (CNTs) with diameters of 0.81 to 4.07 nm. Without an electric field, methanol molecules fill the CNTs in preference to water molecules. The preference of methanol to occupy the CNTs over water results in a separation effect. This separation effect is strong for small CNT diameters and significantly decreases with increasing diameter. In contrast, under an electric field, water molecules strongly prefer to occupy the CNTs over methanol molecules, resulting in a separation effect for water. More interestingly, the separation effect for water does not decrease with increasing CNT diameter. Formation of water structures in CNTs induced by an electric field has an important role in the separation of water from methanol.Methanol is used in various applications, such as fuel for transportation vehicles, fuel cells, and in chemical industrial processes. Conventionally, separation of methanol from aqueous solution is by distillation. However, this method consumes a large amount of energy; hence development of a new method is needed. In this work, molecular dynamics simulations are performed to investigate the effect of an electric field on water-methanol separation by carbon nanotubes (CNTs) with diameters of 0.81 to 4.07 nm. Without an electric field, methanol molecules fill the CNTs in preference to water molecules. The preference of methanol to occupy the CNTs over water results in a separation effect. This separation effect is strong for small CNT diameters and significantly decreases with increasing
Integrated optical waveguide sensor for lighting impulse electric field measurement
Zhang, Jiahong; Chen, Fushen; Sun, Bao; Chen, Kaixin
2014-09-01
A Lithium niobate (LiNbO3) based integrated optical E-field sensor with an optical waveguide Mach-Zehnder interferometer (MZI) and a tapered antenna has been designed and fabricated for the measurement of the pulsed electric field. The minimum detectable E-field of the sensor was 10 kV/m. The sensor showed a good linear characteristic while the input E-fields varied from 10 kV/m to 370 kV/m. Furthermore, the maximum detectable E-field of the sensor, which could be calculated from the sensor input/output characteristic, was approximately equal to 1000 kV/m. All these results suggest that such sensor can be used for the measurement of the lighting impulse electric field.
ELF electric and magnetic fields: Pacific Northwest Laboratory studies
Energy Technology Data Exchange (ETDEWEB)
Anderson, L.E.
1992-06-01
Studies have been conducted at Battelle, Pacific Northwest Laboratory, to examine extremely-low-frequency (ELF) electromagnetic fields for possible biological effects in animals. Three areas of investigation are reported here: (1) studies on the nervous system, including behavior and neuroendocrine function, (2) experiments on cancer development in animals, and (3) measurements of currents and electric fields induced in animal models by exposure to external magnetic fields. In behavioral experiments, rats have been shown to be responsive to ELF electric field exposure. Furthermore, experimental data indicate that short-term memory may be affected in albino rats exposed to combined ELF and static magnetic fields. Neuroendocrine studies have been conducted to demonstrate an apparent stress-related response in rats exposed to 60-Hz electric fields. Nighttime pineal melatonin levels have been shown to be significantly depressed in animals exposed to either electric or magnetic fields. A number of animal tumor models are currently under investigation to examine possible relationships between ELF exposure and carcinogenesis. Finally, theoretical and experimental measurements have been performed which form the basis for animals and human exposure comparisons.
Formation of electric dipoles in pea stem tissue due to an electric field
Ahmadi, Fatemeh; Farahani, Elham
2016-07-01
For examining the effect of an electrical field (DC) on pea seed, we exposed the pea seeds to electric fields with intensities 1, 4 and 7 kV/cm for 30, 230, 430 and 630 seconds. The tests were repeated three times, and each iteration had 5 seeds. Then, the seeds were moved to packaged plates. Finally, microscopic observation of the pea stem tissue showed that the application of a DC electrical field caused a deformation in the pea stem tissue. The results led us to examine the deformation of the tissue theoretically and to address that deformation as an electrostatic problem. In this regard, we modeled the pea stem based on the formation of electric dipoles. Then, theoretically, we calculated the force acting on each xylem section by coding, and the results were consistent with the experimental data.
Electric Field Detection in Sawfish and Shovelnose Rays
Wueringer, Barbara E.; Jnr, Lyle Squire; Kajiura, Stephen M.; Tibbetts, Ian R.; Hart, Nathan S.; Collin, Shaun P.
2012-01-01
In the aquatic environment, living organisms emit weak dipole electric fields, which spread in the surrounding water. Elasmobranchs detect these dipole electric fields with their highly sensitive electroreceptors, the ampullae of Lorenzini. Freshwater sawfish, Pristis microdon, and two species of shovelnose rays, Glaucostegus typus and Aptychotrema rostrata were tested for their reactions towards weak artificial electric dipole fields. The comparison of sawfishes and shovelnose rays sheds light on the evolution and function of the elongated rostrum (‘saw’) of sawfish, as both groups evolved from a shovelnose ray-like ancestor. Electric stimuli were presented both on the substrate (to mimic benthic prey) and suspended in the water column (to mimic free-swimming prey). Analysis of around 480 behavioural sequences shows that all three species are highly sensitive towards weak electric dipole fields, and initiate behavioural responses at median field strengths between 5.15 and 79.6 nVcm−1. The response behaviours used by sawfish and shovelnose rays depended on the location of the dipoles. The elongation of the sawfish’s rostrum clearly expanded their electroreceptive search area into the water column and enables them to target free-swimming prey. PMID:22848543
Carrier heating in disordered conjugated polymers in electric field
Energy Technology Data Exchange (ETDEWEB)
Vukmirovic, Nenad; Wang, Lin-Wang
2010-01-26
The electric field dependence of charge carrier transport and the effect of carrier heating in disordered conjugated polymers were investigated. A parameter-free multiscale methodology consisting of classical molecular dynamics simulation for the generation of the atomic structure, large system electronic structure and electron-phonon coupling constants calculations and the procedure for extracting the bulk polymer mobility, was used. The results suggested that the mobility of a fully disordered poly(3-hexylthiophene) (P3HT) polymer increases with electric field which is consistent with the experimental results on samples of regiorandom P3HT and different from the results on more ordered regioregular P3HT polymers, where the opposite trend is often observed at low electric fields. We calculated the electric field dependence of the effective carrier temperature and showed however that the effective temperature cannot be used to replace the joint effect of temperature and electric field, in contrast to previous theoretical results from phenomenological models. Such a difference was traced to originate from the use of simplified Miller-Abrahams hopping rates in phenomenological models in contrast to our considerations that explicitly take into account the electronic state wave functions and the interaction with all phonon modes.
MEFISTO An electric field instrument for BepiColombo/MMO
Blomberg, L. G.; Matsumoto, H.; Bougeret, J.-L.; Kojima, H.; Yagitani, S.; Cumnock, J. A.; Eriksson, A. I.; Marklund, G. T.; Wahlund, J.-E.; Bylander, L.; Åhlén, L.; Holtet, J. A.; Ishisaka, K.; Kallio, E.; Kasaba, Y.; Matsuoka, A.; Moncuquet, M.; Mursula, K.; Omura, Y.; Trotignon, J. G.
2006-01-01
MEFISTO, together with the companion instrument WPT, are planning the first-ever in situ measurements of the electric field in the magnetosphere of planet Mercury. The instruments have been selected by JAXA for inclusion in the BepiColombo/MMO payload, as part of the Plasma Wave Investigation coordinated by Kyoto University. The magnetosphere of Mercury was discovered by Mariner 10 in 1974 and will be studied further by Messenger starting in 2011. However, neither spacecraft did or will measure the electric field. Electric fields are crucial in the dynamics of a magnetosphere and for the energy and plasma transport between different regions within the magnetosphere as well as between the magnetosphere and the surrounding regions. The MEFISTO instrument will be capable of measuring electric fields from DC to 3 MHz, and will thus also allow diagnostics of waves at all frequencies of relevance to the Hermean magnetosphere. MEFISTO is a double-probe electric field instrument. The double-probe technique has strong heritage and is well proven on missions such as Viking, Polar, and Cluster. For BepiColombo, a newly developed deployment mechanism is planned which reduces the mass by a factor of about 5 compared to conventional mechanisms for 15 m long booms. We describe the basic characteristics of the instrument and briefly discuss the new developments made to tailor the instrument to flight in Mercury orbit.
MEFISTO - an electric field instrument for BepiColombo/MMO
Blomberg, L. G.; Mefisto Team
MEFISTO, together with the companion instrument PANT, are planning the first-ever in-situ measurements of the electric field in the magnetosphere of planet Mercury. The instruments are proposed to JAXA for inclusion in the BepiColombo/MMO payload, as part of the Plasma Wave Investigation co-ordinated by Kyoto University. The magnetosphere of Mercury was discovered by Mariner 10 in 1974, and will be studied further by Messenger starting in 2009. However, neither spacecraft measures the electric field. Electric fields are crucial in the dynamics of a magnetosphere and for the energy and plasma transport between different regions within the magnetosphere as well as between the magnetosphere and the surrounding regions. The instrument will be capable of measuring electric fields from DC to 3 MHz, and will thus also allow diagnostics of waves at all frequencies of relevance to the Hermean magnetosphere. MEFISTO is a double-probe electric field instrument. The double-probe technique has strong heritage and is well proven on missions such as Viking, Freja, and Cluster. For BepiColombo, a newly developed deployment mechanism is planned which reduces the mass by a factor of about 5 compared to conventional mechanisms. We describe the basic characteristics of the instrument and briefly discuss the new developments made to tailor the instrument to flight in Mercury orbit.
Additional electric field in real trench MOS barrier Schottky diode
Mamedov, R. K.; Aslanova, A. R.
2016-04-01
In real trench MOS barrier Schottky diode (TMBS diode) additional electric field (AEF) the whole is formed in the near contact region of the semiconductor and its propagation space is limited with the barrier metal and the metallic electrodes of MOS structures. Effective potential barrier height TMBS diode is formed via resulting electric field of superposition AEF and electric field of space charge region (SCR) semiconductor. The dependence of the resulting electric field intensity of the distance towards the inside the semiconductor is nonlinear and characterized by a peak at a certain distance from the interface. The thickness of the SCR in TMBS diode becomes equal to the trench depth. Force and energy parameters of the AEF, and thus resulting electric field in the SCR region, become dependent on the geometric design parameters TMBS diode. The forward I-V characteristic TMBS diode is described by the thermionic emission theory as in conventional flat Scottky diode, and in the reverse bias, current is virtually absent at initial voltage, appears abruptly at a certain critical voltage.
Ramezani, Zeinab; Orouji, Ali A.
2017-04-01
To achieve reliable transistors, we propose a new silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET) with an amended electric field in the channel for improved electrical and thermal performance, with an emphasis on current leakage improvement. The amended electric field leads to lower electric field crowding and thereby we assume enhanced reliability, leakage current, gate-induced drain leakage (GIDL), and electron temperature. To modify the electric field distribution, an additional rectangular metal region (RMR) is utilized in the buried oxide of the SOI MOSFET. The location and dimensions of the RMR have been carefully optimized to achieve the best results. The electrical, thermal, and radiofrequency characteristics of the proposed structure were analyzed using two-dimensional (2-D) numerical simulations and compared with the characteristics of the conventional, fully depleted SOI MOSFET (C-SOI). Also, critical short-channel effects (SCEs) such as threshold voltage, drain-induced barrier lowering (DIBL), subthreshold slope degradation, hot-carrier effect, GIDL, and leakage power consumption are improved. According to the results obtained, the proposed nano SOI MOSFET is a reliable device, especially for use in low-power and high-temperature applications.
Electric field confinement effect on charge transport in organic field-effect transistors
Li, X.; Kadashchuk, A.; Fishchuk, I.I.; Smaal, W.T.T.; Gelinck, G.H.; Broer, D.J.; Genoe, J.; Heremans, P.; Bässler, H.
2012-01-01
While it is known that the charge-carrier mobility in organic semiconductors is only weakly dependent on the electric field at low fields, the experimental mobility in organic field-effect transistors using silylethynyl-substituted pentacene is found to be surprisingly field dependent at low source-
Electric field enhanced hydrogen storage on polarizable materials substrates.
Zhou, J; Wang, Q; Sun, Q; Jena, P; Chen, X S
2010-02-16
Using density functional theory, we show that an applied electric field can substantially improve the hydrogen storage properties of polarizable substrates. This new concept is demonstrated by adsorbing a layer of hydrogen molecules on a number of nanomaterials. When one layer of H(2) molecules is adsorbed on a BN sheet, the binding energy per H(2) molecule increases from 0.03 eV/H(2) in the field-free case to 0.14 eV/H(2) in the presence of an electric field of 0.045 a.u. The corresponding gravimetric density of 7.5 wt% is consistent with the 6 wt% system target set by Department of Energy for 2010. The strength of the electric field can be reduced if the substrate is more polarizable. For example, a hydrogen adsorption energy of 0.14 eV/H(2) can be achieved by applying an electric field of 0.03 a.u. on an AlN substrate, 0.006 a.u. on a silsesquioxane molecule, and 0.007 a.u. on a silsesquioxane sheet. Thus, application of an electric field to a polarizable substrate provides a novel way to store hydrogen; once the applied electric field is removed, the stored H(2) molecules can be easily released, thus making storage reversible with fast kinetics. In addition, we show that materials with rich low-coordinated nonmetal anions are highly polarizable and can serve as a guide in the design of new hydrogen storage materials.
Biological proton pumping in an oscillating electric field
Kim, Young C.; Furchtgott, Leon A.; Hummer, Gerhard
2009-01-01
Time-dependent external perturbations provide powerful probes of the function of molecular machines. Here we study biological proton pumping in an oscillating electric field. The protein cytochrome c oxidase is the main energy transducer in aerobic life, converting chemical energy into an electric potential by pumping protons across a membrane. With the help of master-equation descriptions that recover the key thermodynamic and kinetic properties of this biological “fuel cell,” we show that t...
Electric Field Structures in Thin Films: Formation and Properties
DEFF Research Database (Denmark)
Cassidy, Andrew; Plekan, Oksana; Balog, Richard
2014-01-01
by combining layers of diﬀerent spontelectric materials. This is demonstrated using the spontelectric materials nitrous oxide, toluene, isoprene, isopentane, and CF2Cl2. These yield a variety of tailored electric ﬁeld structures, with individual layers harboring ﬁelds between 107 and 108 V/m. Fields may......A newly discovered class of molecular materials, so-called “spontelectrics”, display spontaneous electric ﬁelds. Here we show that the novel properties of spontelectrics can be used to create composite spontelectrics, illustrating how electric ﬁelds in solid ﬁlms may be structured on the nanoscale...
Resistance switching induced by electric fields in manganite thin films
Energy Technology Data Exchange (ETDEWEB)
Villafuerte, M [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina); Juarez, G [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina); Duhalde, S [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Golmar, F [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Degreef, C L [Dpto de Fisica, Facultad de IngenierIa, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Heluani, S P [Facultad de Ciencias Exactas y TecnologIa, Universidad Nacional de Tucuman, S. M. de Tucuman (Argentina)
2007-04-15
In this work, we investigate the polarity-dependent Electric Pulses Induced Resistive (EPIR) switching phenomenon in thin films driven by electric pulses. Thin films of {sub 0.5}Ca{sub 0.5}MnO{sub 3} (manganite) were deposited by PLD on Si substrate. The transport properties at the interface between the film and metallic electrode are characterized in order to study the resistance switching. Sample thermal treatment and electrical field history are important to be considered for get reproducible EPIR effect. Carriers trapping at the interfaces are considered as a possible explanation of our results.
Improved theory of cyclical electrical field flow fractionation.
Kantak, Ameya; Merugu, Srinivas; Gale, Bruce K
2006-07-01
Previously reported theories for cyclical electrical field flow fractionation (CyElFFF) are severely limited in that they do not account for diffusion, steric, or electric double layer effects. Experiments have shown that these theories overpredict the retention of particles in CyElFFF. In this work, we present a model for prediction of steric, diffusion, and electrical effects. The electrical double layer effects are treated using a lumped electrical circuit model that accounts for the field shielding by the electrical double layer formed at the electrode-carrier interface. The electrical effects are shown to dominate retention times and outweigh the contributions of diffusion and particle size. Detailed results from the simulations are presented in this work, and a comparison between the theoretical and experimental results obtained from the retentions of polystyrene particle standards is presented in this paper. The models are shown to correctly predict the retention of the polystyrene standards in CyElFFF with a reasonable error, while existing models are shown to have significant failings.
Effect of AC electric fields on flame spread over electrical wire
Kim, Minkuk
2011-01-01
The effect of electric fields on the characteristics of flame spread over insulated electrical wire has been investigated experimentally by varying AC voltage and frequency applied to the wire in the normal gravity condition. The polyethylene (PE) insulated electrical wire was placed horizontally on electrically non-conducting posts and one end of the wire was connected to the high voltage terminal. Thus, the electrical system is the single electrode configuration. The wire was ignited at one end and the flame spread rate along the wire has been measured from the images using a video camera. Two distinct regimes existed depending on the applied AC frequency. In the low frequency regime, the flame spread rate decreased with the frequency and voltage. While in the high frequency regime, it decreased initially with voltage and then increased. At high frequency, the spread rate was even over that without applying electric fields. This result implies that fire safety codes developed without considering the effect of electric fields may require modifications. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.
On the ionospheric coupling of auroral electric fields
Directory of Open Access Journals (Sweden)
G. T. Marklund
2009-04-01
Full Text Available The quasi-static coupling of high-altitude potential structures and electric fields to the ionosphere is discussed with particular focus on the downward field-aligned current (FAC region. Results are presented from a preliminary analysis of a selection of electric field events observed by Cluster above the acceleration region. The degree of coupling is here estimated as the ratio between the magnetic field-aligned potential drop, ΔΦ_{II}, as inferred from the characteristic energy of upward ion (electron beams for the upward (downward current region and the high-altitude perpendicular (to B potential, ΔΦ_{bot}, as calculated by integrating the perpendicular electric field across the structure. For upward currents, the coupling can be expressed analytically, using the linear current-voltage relation, as outlined by Weimer et al. (1985. This gives a scale size dependent coupling where structures are coupled (decoupled above (below a critical scale size. For downward currents, the current-voltage relation is highly non-linear which complicates the understanding of how the coupling works. Results from this experimental study indicate that small-scale structures are decoupled, similar to small-scale structures in the upward current region. There are, however, exceptions to this rule as illustrated by Cluster results of small-scale intense electric fields, correlated with downward currents, indicating a perfect coupling between the ionosphere and Cluster altitude.
Calculation and measurement of electric field under HVDC transmission lines
Kasdi, A.; Zebboudj, Y.; Yala, H.
2007-03-01
A stable corona discharge in a two conductors-to-plane configuration is analysed in this paper. A linear biased probe, without end-effect, has been adapted to a linear geometry and is used for the first time to measure the ground-plane current density and electric field during the bipolar corona. The values of the electric field and the current density are maximum under the two coronating conductors and decrease when moving away from them. Furthermore, a hybrid technique is developed to obtain a general solution of the governing equations of the coupled space-charge and electric field problem. The technique is to use the finite-element method (FEM) to solve Poisson's equation, and the method of characteristic (MOC) to find the charge density from a current-continuity relation. The model avoids resorting to the Deutsch assumption. The computed values are in good agreement with experimental data.
High School Students' Understandings and Representations of the Electric Field
Cao, Ying
2014-01-01
This study investigates the understandings and representations of the electric field expressed by Chinese high school students ages 15 to 16 who have not yet received high school-level physics instruction. The literature has reported students' ideas of the electric field post-instruction as indicated by their performance on textbook-style questionnaires. However, by relying on measures such as questionnaires, previous research has inadequately captured the thinking process that led students to answer questions in the ways that they did. The present study portrays the beginning of this process by closely examining students' understandings pre-instruction. The participants in this study were asked to engage in a lesson that included informal group tasks that involved playing a Web-based hockey game that replicated an electric field and drawing comic strips that used charges as characters. The lesson was videotaped, students' work was collected, and three students were interviewed afterward to ascertain more det...
Incompressible Einstein–Maxwell fluids with specified electric fields
Indian Academy of Sciences (India)
S Hansraj; S D Maharaj; T Mthethwa
2013-10-01
The Einstein–Maxwell equations describing static charged spheres with uniform density and variable electric field intensity are studied. The special case of constant electric field is also studied. The evolution of the model is governed by a hypergeometric differential equation which has a general solution in terms of special functions. Several classes of exact solutions are identified which may be considered as charged generalizations of the incompressible Schwarzschild interior model. An analysis of the physical features is undertaken for the uniform case. It is demonstrated that uniform density spheres with constant electric field intensity are not realizable with isotropic pressures. This highlights the necessity of studying the criteria for physical admissability of gravitating spheres in general relativity which are solutions to the Einstein–Maxwell equations.
Method of using an electric field controlled emulsion phase contactor
Scott, Timothy C.
1993-01-01
A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.
Liesegang patterns: Complex formation of precipitate in an electric field
Indian Academy of Sciences (India)
István Lagzi
2005-02-01
Formation of 1D Liesegang patterns was studied numerically in precipitation and reversible complex formation of precipitate scenarios in an electric field. The Ostwald’s supersaturation model reported by Büki, Kárpáti-Smidróczki and Zrínyi (BKZ model) was extended further. In the presence of an electric field the position of the first and the last bands () measured from the junction point of the outer and the inner electrolytes can be described by the function = 1 $_{}^{1/2}$ + 2 + 3 , where is the time elapsed until the nth band formation, 1, 2 and 3 are constants. The variation of the total number of bands with different electric field strengths () has a maximum. For higher one can observe a moving precipitation zone that becomes wider due to precipitation and reversible complex formation.
Microspacecraft and Earth observation: Electrical Field (ELF) measurement project
1990-01-01
There is a need for an inexpensive, extensive, long-lasting global electric field measurement system (ELF). The primary performance driver of this mission is the need to measure the attitude of each spacecraft in the Earth's electric field very accurately. In addition, it is necessary to know the electric charge generated by the satellite as it crosses the magnetic field lines (E equals V times B). In order to achieve the desired global coverage, a constellation of about 50 satellites in at least 18 different orbits will be used. To reduce the cost of each satellite, off-the-shelf, proven technology will be used whenever possible. Researchers have set a limit of $500,000 per satellite. Researchers expect the program cost, including the deployment of the entire constellation, to be less than $100 million. The minimum projected mission life is five years.
Built-in electric field thickness design for betavoltaic batteries
Institute of Scientific and Technical Information of China (English)
Chen Haiyang; Li Darang; Yin Jianhua; Cai Shengguo
2011-01-01
Isotope source energy deposition along the thickness direction of a semiconductor is calculated,based upon which an ideal short current is evaluated for betavoltaic batteries.Electron-hole pair recombination and drifting length in a PN junction built-in electric field are extracted by comparing the measured short currents with the ideal short currents.A built-in electric field thickness design principle is proposed for betavoltaic batteries:after measuring the energy deposition depth and the carrier drift length,the shorter one should then be chosen as the built-in electric field thickness.If the energy deposition depth is much larger than the carrier drift length,a multijunction is preferred in betavoltaic batteries and the number of the junctions should be the value of the deposition depth divided by the drift length.
Built-in electric field thickness design for betavoltaic batteries
Energy Technology Data Exchange (ETDEWEB)
Chen Haiyang; Li Darang; Yin Jianhua; Cai Shengguo, E-mail: haiyangchen@bit.edu.cn [School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China)
2011-09-15
Isotope source energy deposition along the thickness direction of a semiconductor is calculated, based upon which an ideal short current is evaluated for betavoltaic batteries. Electron-hole pair recombination and drifting length in a PN junction built-in electric field are extracted by comparing the measured short currents with the ideal short currents. A built-in electric field thickness design principle is proposed for betavoltaic batteries: after measuring the energy deposition depth and the carrier drift length, the shorter one should then be chosen as the built-in electric field thickness. If the energy deposition depth is much larger than the carrier drift length, a multi-junction is preferred in betavoltaic batteries and the number of the junctions should be the value of the deposition depth divided by the drift length. (semiconductor devices)
The effect of electric fields on lipid membranes
Vasilkoski, Z
2006-01-01
Contrary to existing theoretical models, experimental evidence points out that electroporation (membrane defect formation under external electric fields) starts to occur within the range of transmembrane voltages that cells may routinely experience, curiously, just above the range of transmembrane voltages involved in neural signal transmission. Understanding the underlying principles of electric fields-lipid membrane interactions seems to carry a great biological importance. An argument is presented toward understanding the theoretical aspects of electroporation by using the DLVO theory, which has not been recognized previously in the context of electroporation. Further, the dispersion interactions (with its quantum nature), of the double layer counterions and membrane lipid molecules over the Stern layer are emphasized. The sign of these forces is such that they compress the membrane. A parallel is drawn to the theory of thin films. The argument is that the external electric field breaks the symmetry of the...
Magnetic field dependence of the threshold electric field in unconventional charge density waves
Dóra, Balázs; Virosztek, Attila; Maki, Kazumi
2002-04-01
Many experiments suggest that the unidentified low-temperature phase of α-(BEDT-TTF)2KHg(SCN)4 is most likely unconventional charge density wave (UCDW). To further extend this identification we present our theoretical study of the threshold electric field of UCDW in a magnetic field. The magnetic field-temperature phase diagram is very similar to those in a d-wave superconductor. The optical conductivity shows clear features characteristic to both UDW and magnetic field. We find a rather strong field dependence of the threshold electric field, which shows qualitatively good agreement with the experimental data.
Measurements of middle-atmosphere electric fields and associated electrical conductivities
Hale, L. C.; Croskey, C. L.; Mitchell, J. D.
1981-01-01
A simple antenna for measuring the vertical electric field in the 'middle atmosphere' has been flown on a number of rocket-launched parachute-borne payloads. The data from the first nine such flights, launched under a variety of geophysical conditions, are presented, along with electrical conductivities measured simultaneously. The data include indications of layered peaks of several volts per meter in the mesospheric field at high and low latitudes in situations of relatively low conductivity. During an auroral 'REP' event the electric field reversed direction in the lower stratosphere, accompanied by a substantial enhancement in conductivity. The data generally do not confirm speculations based only on the extension of the thunderstorm circuit from below or the mapping of ionospheric and magnetospheric fields from above, but seem to require, in addition, internal generation processes in the middle atmosphere.
Uniform electric field induced lateral migration of a sedimenting drop
Bandopadhyay, Aditya; Chakraborty, Suman
2015-01-01
We investigate the motion of a sedimenting spherical drop in the presence of an applied uniform electric field in an otherwise arbitrary direction in the limit of low surface charge convection. We analytically solve the electric potential in and around the leaky dielectric drop, and solve for the Stokesian velocity and pressure fields. We obtain the drop velocity through perturbations in powers of the electric Reynolds number which signifies the importance of the charge relaxation time scale as compared to the convective time scale. We show that in the presence of electric field either in the sedimenting direction or orthogonal to it, there is a change in the drop velocity only in the direction of sedimentation due to an asymmetric charge distribution in the same direction. However, in the presence of an electric field applied in both the directions, and depending on the permittivities and conductivities of the two fluids, we obtain a non-intuitive lateral migration of drop in addition to the buoyancy driven ...
Nanoelectrospray emitter arrays providing interemitter electric field uniformity.
Kelly, Ryan T; Page, Jason S; Marginean, Ioan; Tang, Keqi; Smith, Richard D
2008-07-15
Arrays of electrospray ionization (ESI) emitters have been reported previously as a means of enhancing ionization efficiency or signal intensity. A key challenge when working with multiple, closely spaced ESI emitters is overcoming the deleterious effects caused by electrical interference among neighboring emitters. Individual emitters can experience different electric fields depending on their relative position in the array, such that it becomes difficult to operate all of the emitters optimally for a given applied potential. In this work, we have developed multi-nanoESI emitters arranged with a circular pattern, which enable the constituent emitters to experience a uniform electric field. The performance of the circular emitter array was compared to a single emitter and to a previously developed linear emitter array, which verified that improved electric field uniformity was achieved with the circular arrangement. The circular arrays were also interfaced with a mass spectrometer via a matching multicapillary inlet, and the results were compared with those obtained using a single emitter. By minimizing interemitter electric field inhomogeneities, much larger arrays having closer emitter spacing should be feasible.
Yakovenko, Olena; Matzui, Ludmila; Danylova, Ganna; Zadorozhnii, Victor; Vovchenko, Ludmila; Perets, Yulia; Lazarenko, Oleksandra
2017-07-01
The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field. Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler.
Yakovenko, Olena; Matzui, Ludmila; Danylova, Ganna; Zadorozhnii, Victor; Vovchenko, Ludmila; Perets, Yulia; Lazarenko, Oleksandra
2017-12-01
The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field.Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler.
Improving NASICON Sinterability through Crystallization under High Frequency Electrical Fields
Directory of Open Access Journals (Sweden)
Ilya eLisenker
2016-03-01
Full Text Available The effect of high frequency (HF electric fields on the crystallization and sintering rates of a lithium aluminum germanium phosphate (LAGP ion conducting ceramic was investigated. LAGP with the nominal composition Li1.5Al0.5Ge1.5(PO43 was crystallized and sintered, both conventionally and under effect of electrical field. Electrical field application, of 300V/cm at 1MHz, produced up to a 40% improvement in sintering rate of LAGP that was crystallized and sintered under the HF field. Heat sink effect of the electrodes appears to arrest thermal runaway and subsequent flash behavior. Sintered pellets were characterized using XRD, SEM, TEM and EIS to compare conventionally and field sintered processes. The as-sintered structure appears largely unaffected by the field as the sintering curves tend to converge beyond initial stages of sintering. Differences in densities and microstructure after 1 hour of sintering were minor with measured sintering strains of 31% vs. 26% with and without field, respectively . Ionic conductivity of the sintered pellets was evaluated and no deterioration due to the use of HF field was noted, though capacitance of grain boundaries due to secondary phases was significantly increased.
Electric-field manipulation of magnetization vector direction
Ohno, Hideo
2009-03-01
Ferromagnetism and magnetization in Mn-doped III-V semiconductors can be manipulated by various means; by changing its carrier concentration by electric fields [1] or by spin- current flowing along with the electric current [2]. This material system is thus an excellent system to study the physics involved in manipulation of magnetism as well as exploring new ways to control magnetization. Here, we show that electrical control of magnetization direction can be done through manipulating electronically the magnetic anisotropy energies [3]. The basic idea behind the effort is to control the population of carriers on spin-split anisotropic valence bands that governs the magnetic anisotropy energies, which should result in change of the direction of magnetization. In order to measure the magnetic anisotropies under a gate that applies the electric-field to the ferromagnetic semiconductor channel, we used the planar Hall effect. Analyses showed that there are biaxial as well as uniaxial anisotropies. As the sheet carrier concentration is reduced by applying electric- field to the channel, the uniaxial anisotropy field reduced its magnitude and eventually changed its sign, whereas no significant change was apparent in the biaxial anisotropy field. From the electric-field dependent anisotropy fields, one can show that the angle of the magnetization direction in the absence of magnetic fields is modulated by electric-fields by 10 degrees. This opens up a new and unique opportunity for manipulating magnetization direction solely by electronic means, not resorting to magnetic-field, spin-current, mechanical stress, nor multiferroics. The conditions for switching the magnetization direction will also be discussed. The work was done together with D. Chiba, F. Matsukura, M. Sawicki, Y. Nishitani, and Y. Nakatani. [4pt] [1] H. Ohno, et al. Nature 408, 944 (2000). D. Chiba, et al. Science, 301, 943 (2003). D. Chiba, et al. Appl. Phys. Lett. 89, 162505 (2006). [0pt] [2] M
Dependence of electric field on STM tip preparation
DEFF Research Database (Denmark)
Huang, D.H.; Grey, Francois; Aono, M.
1998-01-01
Voltage pulses applied between an STM tip and a surface can modify the surface on the nanometer scale due to electric-field-induced evaporation. However, at present, different groups have achieved surface modification with quite different bias conditions, and it is still difficult to obtain high...... reproducibility in such experiments. In this paper, we measure the tip displacement during a pulse at constant tunnelling current, and deduce that the electric field produced by the pulse depends in a systematic way on tip preparation, The results show how differences in tip preparation can be a major source...
Dynamic electrophoresis of charged colloids in an oscillating electric field.
Shih, Chunyu; Yamamoto, Ryoichi
2014-06-01
The dynamics of charged colloids in an electrolyte solution is studied using direct numerical simulations via the smoothed profile method. We calculated the complex electrophoretic mobility μ(ω) of the charged colloids under an oscillating electric field of frequency ω. We show the existence of three dynamically distinct regimes, determined by the momentum diffusion and ionic diffusion time scales. The present results agree well with approximate theories based on the cell model in dilute suspensions; however, systematic deviations between the simulation results and theoretical predictions are observed as the volume fraction of colloids is increased, similar to the case of constant electric fields.
Mechanism of Carbon Nanotubes Aligning along Applied Electric Field
Institute of Scientific and Technical Information of China (English)
MA Shao-Jie; GUO Wan-Lin
2008-01-01
The mechanism of single-walled carbon nanotubes (SWCNTS)aligning in the direction of external electric field is studied by quantum mechanics calculations.The rotational torque on the carbon nanotubes is proportional to the difference between the longitudinal and transverse polarizabilities and varies with the angle of SWCNTs to the external electric field.The longitudinal polarizability increases with second power of length,while the transverse polarizability increases linearly with length.A zigzag SWCNT has larger longitudinal and transverse polarizabilities than an armchair SWCNT with the same diameter and the discrepancy becomes larger for longer tubes.
Characterization of complementary electric field coupled resonant surfaces
Hand, Thomas H.; Gollub, Jonah; Sajuyigbe, Soji; Smith, David R.; Cummer, Steven A.
2008-11-01
We present angle-resolved free-space transmission and reflection measurements of a surface composed of complementary electric inductive-capacitive (CELC) resonators. By measuring the reflection and transmission coefficients of a CELC surface with different polarizations and particle orientations, we show that the CELC only responds to in-plane magnetic fields. This confirms the Babinet particle duality between the CELC and its complement, the electric field coupled LC resonator. Characterization of the CELC structure serves to expand the current library of resonant elements metamaterial designers can draw upon to make unique materials and surfaces.
Nonlinear Optical Response of Conjugated Polymer to Electric Field
Institute of Scientific and Technical Information of China (English)
ZHOU Yu-fang; ZHUANG De-xin; CUI Bin
2005-01-01
The organic π-conjugated polymers are of major interest materials for the use in electro-optical and nonlinear optical devices. In this work, for a selected polyacetylene chain, the optical absorption spectra in UV/Vis regime as well as the linear polarizabilitiy and nonlinear hyperpolarizability are calculated by using quantum chemical ab initio and semiempirical methods. The relationship of its optical property to electric field is obtained. Some physical mechanism of electric field effect on molecular optical property is discussed by means of electron distribution and intramolecular charge transfer.
Brane Intersections in the Presence of a Worldvolume Electric Field
Bhattacharya, R; Bhattacharyya, Rajsekhar; Douari, Jamila
2005-01-01
The study of brane intersections has provided important insights into a possible non-commutative structure of spacetime geometry. In this paper we focus on the D1$\\bot$D3 system. We compare the D1 and D3 descriptions of the interesection and search for non-static solutions of the D3$\\bot$D1 funnel equations in the presence of a worldvolume electric field. We find that the D1 and D3 descriptions do not agree. We find time dependent solutions that are a natural generalization of those found without the electric field.
Generation of Radial Electric Field with Electrode Biasing
Institute of Scientific and Technical Information of China (English)
WANG Cheng; PAN Ge-Sheng; WEN Yi-Zhi; YU Chang-Xuan; WAN Shu-De; LIU Wan-Dong; WANG Zhi-Jiang; SUN Xuan
2001-01-01
Time and space resolved measurements of the radial electric field (Er) have been conducted during the electrode biasing experiments on the KT-5C tokamak. The suppression of the turbulent transport with the change of Er induced by the biased electrode is observed. It is found that the poloidal flow contributes to the main part of the Er, and the change of the poloidal flow has a lead of about 20μs to the formation of Er. These observations suggest that a radialcurrent, responding to an induced voltage on the electrode, drives a poloidal flow which in turn drives the radial electric field.
Reduced dielectric response in spatially varying electric fields
DEFF Research Database (Denmark)
Hansen, Jesper Schmidt
2015-01-01
In this paper, the dynamical equation for polarization is derived. From this the dielectric response to a spatially varying electric field is analyzed showing a reduced response due to flux of polarization in the material. This flux is modeled as a diffusive process through linear constitutive...... relations between the flux and the gradient of the polarization. Comparison between the theory and molecular dynamics simulations confirms this effect. The effect is significant for small length scale electric field variations and the inclusion of the flux is thus important in nanoscale modeling...
Electric field effects in scanning tunneling microscope imaging
DEFF Research Database (Denmark)
Stokbro, Kurt; Quaade, Ulrich; Grey, Francois
1998-01-01
We present a high-voltage extension of the Tersoff-Hamann theory of scanning tunneling microscope (STM) images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first-principles electronic structure calculations and has no adjustable...... parameters. We use the method to calculate theoretical STM images of the monohydrate Si(100)-H(2x1) surface with missing hydrogen defects at -2V and find an enhanced corrugation due to the electric field, in good agreement with experimental images....
Integrated optical electric field sensor with telescopic dipole
Institute of Scientific and Technical Information of China (English)
Bao Sun; Fushen Chen; Yongjun Yang
2008-01-01
An integrated optical electric field sensor based on a Mach-Zehnder interferometer with the telescopic dipole is designed and fabricated, and its electrodes are segmented and connected with a telescopic dipole.The measured results show that when the frequency response is from 10kHz to 6GHz with the antenna length of 55mm, the minimum detectable electric field of 20mV/m can be obtained, and the linear dynamics range can reach 90dB at 250MHz.
PRESERVATION OF AVOCADO OIL WITH ELECTRIC FIELD TREATMENT
J.A. Ariza-Ortega; E. Ramírez-Moreno; M.E. Ramos-Cassellis; J. Díaz-Reyes
2014-01-01
The aim of this study was to analyze the effect of different conditions of electric field (voltage 3 kV cm-1, 60 Hz, 10 and 180 s; 720 Hz, 10 and 180 s) as method on preservation up to 365 days on oil extracted of the avocado pulp. Unsaturated fatty acid oxidation in crude avocado oil was analyzed by Fourier transform infrared spectroscopy technique in the mid infrared region and by quality parameters (acidity, peroxide and iodine). The electric field caused minimal changes on unsaturated fat...
Linear oscillations of a drop in uniform alternating electric fields
Energy Technology Data Exchange (ETDEWEB)
Yang, Wenrui; Carleson, T.E.
1990-10-01
Oscillations of a conducting drop immersed in a dielectric fluid in an alternating electric field has been modelled in order to understand the enhancement of the transport processes by the electric field. Numerical solutions for oscillation amplitude, velocity distribution, resonant frequency and streamlines were obtained. The effects of viscosity and density on the resonant frequency and the velocity distribution were investigated. It was found that the resonant frequency of viscous fluids was always smaller than the free oscillation frequency of the same droplet. The predicted scanning frequency response curve and the streamlines agree well with the experimental observations.
Hyperpolarisation effects on the electric field gradient at a nucleus
Fowler, P. W.
1989-04-01
The electric field gradient at the nucleus of an atom or ion depends quadratically on the external electric field through the ɛ hyperpolarisability. Ab initio Hartree-Fock calculations on the He, Ne and Ar isoelectronic series show that ɛ is positive for s 2 and negative for p 6 electronic configurations, always having the opposite sign to the Sternheimer antishielding factor. The ab initio values for free atoms and ions conflict in sign with the effective hyperpolarisation term in one ionic model of nuclear quadrupole constants of gaseous alkali halides but the sign of the empirical parameter could change if overlap damping of the Sternheimer response were included in the model.
Institute of Scientific and Technical Information of China (English)
REN ZhiPeng; WAN WeiXing; WEI Yong; LIU LiBo; YU Tao
2008-01-01
The geomagnetic fields, which play important roles in the ionospheric dynamo, can greatly affect the global distribution of ionospheric electric fields, currents and other ionospheric electrodynamics phenomena. In the study of ionospheric electrodynamics phenomena, such as the longitudinal variations of ionospheric electric fields, the non-dipolar component of the geomagnetic fields must be taken into account. In this paper, we deduce a theoretical electric field model for ionospheric dynamo at midand low-latitude which adopt a modified magnetic apex coordinates system. In the new electric field model, the geomagnetic fields can be calculated from either the IGRF model or the dipole field model,and the neutral winds and conductivities are calculated based on empirical models. Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method, and the ionospheric electric fields and currents are derived from the calculated potential. Our model can reproduce the main features of the ionospheric electrodynamics processes, so it will be a useful tool for the investigation of the upper atmosphere and ionosphere.
Electric field tuning of phase separation in manganite thin films
Lourembam, James
2014-01-29
In this paper, we investigate the electric field effect on epitaxial Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films in electric double-layer transistors. Different from the conventional transistors with semiconducting channels, the sub(micrometer)-scale phase separation in the manganite channels is expected to result in inhomogeneous distribution of mobile carriers and local enhancement of electric field. The field effect is much larger in the low-temperature phase separation region compared to that in the high-temperature polaron transport region. Further enhancement of electroresistance is achieved by applying a magnetic field, and a 250% modulation of resistance is observed at 80 K, equivalent to an increase of the ferromagnetic metallic phase fraction by 0.51%, as estimated by the general effective medium model. Our results illustrate the complementary nature of electric and magnetic field effects in phase-separated manganites, providing insights on such novel electronic devices based on complex oxides.
Bazelyan, E. M.; Raizer, Yu. P.; Aleksandrov, N. L.
2014-03-01
The properties of a non-stationary glow corona maintained near the tips of a multi-point ground system in a time-varying thundercloud electric field have been studied numerically and analytically. Computer and analytical models were developed to simulate the corona discharge initiated from a system of identical vertical conductive electrodes distributed uniformly over a grounded plane surface. The simulation was based on a solution of the electrostatic equation for electric field and continuity equations for light and aerosol ions. The development of individual corona space charge layers from different points and the formation of a united plane layer were considered. The effect of system dimensions and that of the distance between electrodes on the external electric field corresponding to corona onset near the rod tips was investigated. The evolution in time of the corona current was calculated for systems with various numbers of coronating rods in time-varying atmospheric electric field. In the limit of infinite number of coronating rods, reasonable agreement was obtained between numerical calculations and analytical theory considering the effect of surrounding rods on the corona discharge from a given rod in a simplified integral way. Conditions were determined under which the corona properties of a multi-point system are similar to the properties of a plane surface emitting ions into the atmosphere. In this case, the corona current density is governed by the time derivative of the thundercloud electric field and is independent of the ion mobility and of the coronating system dimensions. The total corona space charge injected into the atmosphere per unit area by a given instant is controlled by the thundercloud electric field at this instant and depends on the geometrical parameters of the system only indirectly, through the corona onset atmospheric electric field. This simple model could be used to simulate a corona discharge during thunderstorms at the earth
Institute of Scientific and Technical Information of China (English)
Baowei Wang; Genhui Xu; Hongwei Sun
2006-01-01
Direct conversion of methane into C2 hydrocarbons through alternating current electric field enhanced plasma was studied under room temperature, atmospheric pressure and low power conditions.The distribution of electrical field intensity and distribution of energy were calculated with software that was developed by us according to the charge simulation method. The results indicated that the energy of tip of electrode was 0.36 J/mm3 and it was higher than the methane dissociation energy (0.0553 J/mm3).The methane located at this area can be activated easily. The higher-energy particles produced by dissociation collided with molecules around them and initiated consecutive reactions between free radicals and molecules. The method was proved to be valided and could be taken as a basis for the electrical field study concerned.
Synthesis of zirconium oxynitride in air under DC electric fields
Energy Technology Data Exchange (ETDEWEB)
Morisaki, Nobuhiro; Tokunaga, Tomoharu; Sasaki, Katsuhiro; Yamamoto, Takahisa, E-mail: yamataka@numse.nagoya-u.ac.jp [Department of Quantum Engineering, Nagoya University, Furocho, Chikusa-ku, Nagoya 464–8603 (Japan); Yoshida, Hidehiro [National Institute for Materials Science, 1–2–1 Sengen, Tsukuba, Ibaraki 305–0047 (Japan); Matsui, Koji [Inorganic Materials Research Laboratory, Tosoh Corporation, 4560 Kaisei-cho, Shunan, Yamaguchi 746-8501 (Japan)
2016-08-22
We synthesized zirconium oxynitride from yttria-stabilized zirconia (YSZ) in air by applying DC electric fields that produced a controlled electric current in the specimen. When YSZ was heated under an applied DC electric field, the electric current of the specimen steeply increased at a critical temperature, called a flash event, during flash sintering. By keeping the electric current of the specimen constant during the flash event and then holding the specimen at the critical temperature, YSZ was transformed into zirconium oxynitride under the optimal conditions of 50 V/cm, 500 mA, and 1000 °C. We confirmed that zirconium oxynitride formed using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and energy-dispersive spectrometry. To convert oxides to nitrides, reducing conditions are necessary to form excess oxygen vacancies. Our technique produced the strong reducing conditions necessary to form nitrides from the oxides by delivering a controlled electric current to the specimen.
Resonances in low frequency ionization by periodic electric fields
Energy Technology Data Exchange (ETDEWEB)
Dando, P.A.; Richards, D. (Open Univ., Milton Keynes (United Kingdom). Mathematics Faculty)
1993-09-28
The behaviour of a one-dimensional system perturbed by a low frequency, periodic electric field is examined in the limit as the field frequency, [Omega], tends to zero, that is the static field limit. In particular we obtain estimates of the widths of each member of the infinite set of resonances between any finite value of [Omega] and 0. In order to obtain this estimate we derive a new analytic approximation of the two-state equations of motion. Our analysis shows why recent experiments on the ionization of excited hydrogen atoms by low frequency fields failed to observe any resonances. (author).
The acceleration of a neutron in a static electric field
Cappelletti, R. L.
2012-06-01
We show that when a non-relativistic neutron travels in a static electric field, the acceleration vector operator is perpendicular to the velocity operator. Kinetic energy is conserved. A spin-dependent field term in the canonical momentum gives rise to a non-dispersive contribution to the quantum mechanical (Aharonov-Casher) phase. This motion differs from that in a static magnetic field which has no field term in the canonical momentum and no conservation of kinetic energy. For the geometry of the Aharonov-Casher effect, there is no acceleration, while in Mott-Schwinger scattering, the acceleration causes a spin-dependent change in neutron direction.
Cohen, Eliahu; Grossman, Doron; Horwitz, Lawrence; Elitzur, Avshalom C
2013-01-01
An experiment is proposed which can distinguish between two approaches to the reality of the electric field, and whether its lines have physical properties such as rigidity and stress. A charged pendulum swings within the field of another charge. If the curvature of the field-lines is a genuine physical phenomenon, the charge's center of mass must be proportionately shifted, in contrast with the conventional interpretation of the curvature as a mere superposition of different field-lines. Granting reality to the electric field may shed new light on several unresolved issues in electromagnetism, classical as well as quantum and relativistic.