WorldWideScience

Sample records for superconductivity-induced self-energy effects

  1. Self-energy dispersion effects on neutron matter superfluidity

    International Nuclear Information System (INIS)

    Zuo Wei

    2001-01-01

    The effects of the dispersion and ground state correlation of the single particle self-energy on neutron matter superfluidity have been investigated in the framework of the Extended Brueckner-Hartree-Fock and the generalized BCS approaches. A sizable reduction of the energy gap is found due to the energy dependence of the self-energy. And the inclusion of the ground state correlations in the self-energy suppresses further the neutron matter superfluidity

  2. Effective interactions for self-energy. I. Theory

    International Nuclear Information System (INIS)

    Ng, T.K.; Singwi, K.S.

    1986-01-01

    A systematic way of deriving effective interactions for self-energy calculations in Fermi-liquid systems is presented. The self-energy expression contains effects of density and spin fluctuations and also multiple scattering between particles. Results for arbitrarily polarized one-component Fermi-liquid systems and unpolarized two-component systems are explicitly given

  3. The self-energy of a heavy quark in the gluonic vacuum and the effective mass

    International Nuclear Information System (INIS)

    Ishizuka, W.; Kikuchi, Y.

    1983-01-01

    We calculate, be use of the multipole expansion, the self-energy of the heavy quark in the gluonic vacuum from which the momentum dependent effective mass is derived. A phenomenological consequence is discussed also. (orig.)

  4. Experimental study of superconductivity induced by proximity effects; Etude experimentale de la supraconductivite induite par effets de proximite

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-15

    We present a study of the proximity effects between a superconductor (InBi or PbBi alloys) and a 'normal' metal (Zn or Sn respectively, above their critical temperature) using essentially the tunneling techniques. On the N side, some specific properties of such an induced superconductivity are described: linear variation of the pair potential near the critical temperature of the binary layer, T{sub CNS}; reduced energy scale at T{sub CNS}; evidence of a thermodynamic critical field (called breakdown field) presented by N above its critical temperature. On the S side, we study crossing from a gapless to a quasi gapless regime. This gives a proof of a finite coherence length at T{sub CNS}. Experimental details (in particular about the preparation and measurement of tunneling junctions) are given in annexe. Possible applications are suggested. (author) [French] Nous presentons une etude experimentale des effets de proximite entre un supraconducteur (alliages d'InBi ou de PbBi) et un metal 'normal' (Zn ou Sn respectivement, pris au-dessus de leur temperature critique), en utilisant principalement des mesures d'effet tunnel. Du cote N, on met en evidence des proprietes specifiques de cette supraconductivite induite: comportement lineaire du potentiel de paires pres de la temperature critique du bilame, T{sub CNS}; echelle d'energie reduite a T{sub CNS}; apparition d'un champ critique thermodynamique (appele champ de basculement) dans N au-dessus de sa temperature critique. Du cote S, nous etudions le passage continu d'une situation 'sans bande interdite' a basse temperature et en champ fort, a une situation 'pratiquement sans bande interdite' pres de T{sub CNS} en champ nul. Ceci fournit une preuve de la non divergence de la longueur de coherence a T{sub CNS}. Les techniques experimentales (et en particulier la preparation et la mesure de jonctions tunnel) sont decrites en detail dans une annexe. On envisage des applications pratiques possibles. (auteur)

  5. Quasiparticle band gap of organic-inorganic hybrid perovskites: Crystal structure, spin-orbit coupling, and self-energy effects

    Science.gov (United States)

    Gao, Weiwei; Gao, Xiang; Abtew, Tesfaye A.; Sun, Yi-Yang; Zhang, Shengbai; Zhang, Peihong

    2016-02-01

    The quasiparticle band gap is one of the most important materials properties for photovoltaic applications. Often the band gap of a photovoltaic material is determined (and can be controlled) by various factors, complicating predictive materials optimization. An in-depth understanding of how these factors affect the size of the gap will provide valuable guidance for new materials discovery. Here we report a comprehensive investigation on the band gap formation mechanism in organic-inorganic hybrid perovskites by decoupling various contributing factors which ultimately determine their electronic structure and quasiparticle band gap. Major factors, namely, quasiparticle self-energy, spin-orbit coupling, and structural distortions due to the presence of organic molecules, and their influences on the quasiparticle band structure of organic-inorganic hybrid perovskites are illustrated. We find that although methylammonium cations do not contribute directly to the electronic states near band edges, they play an important role in defining the band gap by introducing structural distortions and controlling the overall lattice constants. The spin-orbit coupling effects drastically reduce the electron and hole effective masses in these systems, which is beneficial for high carrier mobilities and small exciton binding energies.

  6. Semiclassical delta self-energy

    International Nuclear Information System (INIS)

    Voutier, E.

    1992-01-01

    We present a semiclassical approach in the Δ self-energy. We show that the in-medium corrections of the Δ width issued from the Pauli blocking and the coupling to the 2N-1h continuum are in good agreement with the previous approaches and particularly with the quantum Δ-h model even for light nuclei. We separate out the different sources of the imaginary part of the self-energy. The predominant corrections come from two antagonistic origins: The Pauli blocking and the contribution to the two-nucleon emission channel, the latter being model dependent. We further show that the non-diagonal spin matrix elements of the self-energy, generated by its tensor component, are mostly due to the Pauli blocking. (orig.)

  7. A new approach to the electron self energy calculation

    International Nuclear Information System (INIS)

    Persson, H.; Lindgren, I.; Salomonson, S.

    1993-01-01

    We present a new practical way to calculate the first order self energy in any model potential (local or non-local). The main idea is to introduce a new straightforward way of renormalization to avoid the usual potential expansion implying a large number of diagrams in higher order QED effects. The renormalization procedure is based on defining the divergent mass term in coordinate space and decomposing it into a divergent sum over finite partial wave contributions. The unrenormalized bound self energy is equally decomposed into a partial wave (l) sum. For each partial wave the difference is taken and the sum becomes convergent. The comparably rapid asymptotic behaviour of the method is l -3 . The method is applied to lithium-like uranium, and the self energy in a Coulomb field, the finite nucleus effect and the screened self energy is calculated to an accuracy of at least one tenth of an eV. (orig.)

  8. Self-energies and the interactions of particles with surfaces

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.; Echenique, P.M.; Gras-Marti, A.

    1987-01-01

    We have in this paper reviewed the method of treating many-body problems by means of an effective interaction self-energy. We have developed an alternatvie approach to the self-energy which is simpler and more straight-forward than standard methods, and we have illustrated its use with two examples of a charge interacting with a metal surface. In each case the self-energy produces the classical image potential together with corrections due to quantum mechanical effects. This method has also been successfully applied to the problem of an atom interacting with a surface. Corrections to the Van der Waals dispersion force are obtained, and via the non-conservative imaginary parts to /summation//sub i/(z) we discuss transition rates and energy exchange. 14 refs., 1 fig

  9. The dielectric environment dependent exchange self-energy of the energy structure in graphene

    International Nuclear Information System (INIS)

    Yang, C.H.; Xu, W.

    2010-01-01

    We theoretically calculate the energy dispersion in the presence of the screened exchange self-energy in extrinsic monolayer graphene. It is found that the exchange self-energy enhances the renormalized Fermi velocity. With decreasing the dielectric constant, the screening effect and the electron correlation effect increase which induces the Fermi velocity increasing. The screened exchange energy has an energy shift at the Dirac points. The self-energy from the valance band carriers gives the main contribution to the effective energy. We also discuss the electron density dependence of the self-energy.

  10. The dielectric environment dependent exchange self-energy of the energy structure in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.H., E-mail: chyang@nuist.edu.c [Faculty of Maths and Physics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Xu, W. [Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2010-10-01

    We theoretically calculate the energy dispersion in the presence of the screened exchange self-energy in extrinsic monolayer graphene. It is found that the exchange self-energy enhances the renormalized Fermi velocity. With decreasing the dielectric constant, the screening effect and the electron correlation effect increase which induces the Fermi velocity increasing. The screened exchange energy has an energy shift at the Dirac points. The self-energy from the valance band carriers gives the main contribution to the effective energy. We also discuss the electron density dependence of the self-energy.

  11. Cd{sub 2}Re{sub 2}O{sub 7}. Temperature dependence of the superconducting order parameter and the effect of quasiparticle self-energy

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, F.S.; Rohanizadegan, Y.; Hajialamdari, M.; Reedyk, M.; Mitrovic, B. [Department of Physics, Brock University, St. Catharines, ON L2S 3A1 (Canada); Kremer, R.K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

    2016-07-01

    The temperature dependence and the magnitude of the superconducting order parameter of single crystals of Cd{sub 2}Re{sub 2}O{sub 7} (T{sub c} = 1.02 K) were measured using soft point-contact spectroscopy. The order parameter, Δ(T), increases steeply below the superconducting transition temperature and levels off below ∝ 0.8 K at a value of 0.22(1) meV, about 40 % larger than the BCS value. Our findings indicate the presence of a strong electron-phonon interaction and an enhanced quasiparticle damping and may be related to a possible phase transition within the superconducting region at ∝ 0.8 K. In order to fit the conductance spectra and to extract the order parameter at different temperatures we generalized the Blonder-Tinkham-Klapwijk theory by including the self-energy of the quasiparticles into the Bogoliubov equations. This modification enabled excellent fits of the conductance spectra.

  12. Giant superconductivity-induced modulation of the ferromagnetic magnetization in a cuprate-manganite superlattice.

    Science.gov (United States)

    Hoppler, J; Stahn, J; Niedermayer, Ch; Malik, V K; Bouyanfif, H; Drew, A J; Rössle, M; Buzdin, A; Cristiani, G; Habermeier, H-U; Keimer, B; Bernhard, C

    2009-04-01

    Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.

  13. Recoil saturation of the self-energy in atomic systems

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.

    1988-01-01

    Within the framework of the general self-energy problem for the interaction of a projectile with a many-body system, we consider the dispersion force between two atoms or between a charge and an atom. Since the Born-Oppenheimer approximation is not made, this is a useful approach for exhibiting non-adiabatic effects. We find compact expressions in terms of matrix elements of operators in the atomic displacement which are not limited by multipole expansions. 7 refs

  14. Self-energy behavior away from the Fermi surface in doped Mott insulators.

    Science.gov (United States)

    Merino, J; Gunnarsson, O; Kotliar, G

    2016-02-03

    We analyze self-energies of electrons away from the Fermi surface in doped Mott insulators using the dynamical cluster approximation to the Hubbard model. For large onsite repulsion, U, and hole doping, the magnitude of the self-energy for imaginary frequencies at the top of the band ([Formula: see text]) is enhanced with respect to the self-energy magnitude at the bottom of the band ([Formula: see text]). The self-energy behavior at these two [Formula: see text]-points is switched for electron doping. Although the hybridization is much larger for (0, 0) than for [Formula: see text], we demonstrate that this is not the origin of this difference. Isolated clusters under a downward shift of the chemical potential, [Formula: see text], at half-filling reproduce the overall self-energy behavior at (0, 0) and [Formula: see text] found in low hole doped embedded clusters. This happens although there is no change in the electronic structure of the isolated clusters. Our analysis shows that a downward shift of the chemical potential which weakly hole dopes the Mott insulator can lead to a large enhancement of the [Formula: see text] self-energy for imaginary frequencies which is not associated with electronic correlation effects, even in embedded clusters. Interpretations of the strength of electronic correlations based on self-energies for imaginary frequencies are, in general, misleading for states away from the Fermi surface.

  15. Quark condensate contributions to the gluon self-energy and the ρ meson sum rule

    International Nuclear Information System (INIS)

    Steele, T.G.

    1989-01-01

    The operator-product expansion will be employed to obtain the lowest-order, quark condensate component of both the gluon self-energy and the ρ meson correlation function to all orders in the quark mass parameter. Field-theoretic aspects of the self-energy and correlation function will be considered, and physical effects to the quark condensate upon gluon mass generation will be examined. (orig.)

  16. Quark self-energy in an ellipsoidally anisotropic quark-gluon plasma

    Science.gov (United States)

    Kasmaei, Babak S.; Nopoush, Mohammad; Strickland, Michael

    2016-12-01

    We calculate the quark self-energy in a quark-gluon plasma that possesses an ellipsoidal momentum-space anisotropy in the local rest frame. By introducing additional transverse-momentum anisotropy parameters into the parton distribution functions, we generalize previous results which were obtained for the case of a spheroidal anisotropy. Our results demonstrate that the presence of anisotropies in the transverse directions affects the real and imaginary parts of quark self-energy and, consequently, the self-energy depends on both the polar and azimuthal angles in the local rest frame of the matter. Our results for the quark self-energy set the stage for the calculation of the effects of ellipsoidal momentum-space anisotropy on quark-gluon plasma photon spectra and collective flow.

  17. Dispersion self-energy of the electron

    International Nuclear Information System (INIS)

    Hawton, M.

    1991-01-01

    Electron mass renormalization and the Lamb shift have been investigated using the dispersion self-energy formalism. If shifts of both the electromagnetic field and quantum-mechanical transitions frequencies are considered, absorption from the electromagnetic field is canceled by emission due to atomic fluctuations. The frequencies of all modes are obtained from the self-consistency condition that the field seen by the electron is the same as the field produced by the expectation value of current. The radiation present can thus be viewed as arising from emission and subsequent reabsorption by matter. As developed here, the numerical predictions of dispersion theory are identical to those of quantum electrodynamics. The physical picture implied by dispersion theory is discussed in the context of semiclassical theories and quantum electrodynamics

  18. Total energy calculations from self-energy models

    International Nuclear Information System (INIS)

    Sanchez-Friera, P.

    2001-06-01

    Density-functional theory is a powerful method to calculate total energies of large systems of interacting electrons. The usefulness of this method, however, is limited by the fact that an approximation is required for the exchange-correlation energy. Currently used approximations (LDA and GGA) are not sufficiently accurate in many physical problems, as for instance the study of chemical reactions. It has been shown that exchange-correlation effects can be accurately described via the self-energy operator in the context of many-body perturbation theory. This is, however, a computationally very demanding approach. In this thesis a new scheme for calculating total energies is proposed, which combines elements from many-body perturbation theory and density-functional theory. The exchange-correlation energy functional is built from a simplified model of the self-energy, that nevertheless retains the main features of the exact operator. The model is built in such way that the computational effort is not significantly increased with respect to that required in a typical density-functional theory calculation. (author)

  19. Scattering amplitude and shift in self-energy in medium

    International Nuclear Information System (INIS)

    Mallik, S.

    2002-01-01

    Two simple proofs are presented for the first order virial expansion of the self-energy of a particle moving through a medium, characterised by temperature and/or chemical potential(s). One is based on the virial expansion of the self-energy operator itself, while the other is based on the analysis of its Feynman diagrams in configuration space. (orig.)

  20. Nucleon self-energy in the relativistic Brueckner theory

    Energy Technology Data Exchange (ETDEWEB)

    Waindzoch, T; Fuchs, C; Faessler, A [Inst. fuer Theoretische Physik, Univ. Tuebingen (Germany)

    1998-06-01

    The self-energy of the nucleon in nuclear matter is calculated in the relativistic Brueckner theory. We solve the Thompson equation for the two nucleon scattering in the medium using different Bonn potentials. The self-energy has a rather strong momentum dependence while the equation of state compares well with previous calculations. (orig.)

  1. Nucleon self-energy in the relativistic Brueckner theory

    International Nuclear Information System (INIS)

    Waindzoch, T.; Fuchs, C.; Faessler, A.

    1998-01-01

    The self-energy of the nucleon in nuclear matter is calculated in the relativistic Brueckner theory. We solve the Thompson equation for the two nucleon scattering in the medium using different Bonn potentials. The self-energy has a rather strong momentum dependence while the equation of state compares well with previous calculations. (orig.)

  2. Cosmic censorship, area theorem, and self-energy of particles

    International Nuclear Information System (INIS)

    Hod, Shahar

    2002-01-01

    The (zeroth-order) energy of a particle in the background of a black hole is given by Carter's integrals. However, exact calculations of a particle's self-energy (first-order corrections) are still beyond our present reach in many situations. In this paper we use Hawking's area theorem in order to derive bounds on the self-energy of a particle in the vicinity of a black hole. Furthermore, we show that self-energy corrections must be taken into account in order to guarantee the validity of Penrose's cosmic censorship conjecture

  3. Exact solutions of linearized Schwinger endash Dyson equation of fermion self-energy

    International Nuclear Information System (INIS)

    Zhou, B.

    1997-01-01

    The Schwinger endash Dyson equation of fermion self-energy in the linearization approximation is solved exactly in a theory with gauge and effective four-fermion interactions. Different expressions for the independent solutions, which, respectively, submit to irregular and regular ultraviolet boundary condition are derived and expounded. copyright 1997 American Institute of Physics

  4. Self-Energy of Decuplet Baryons in Nuclear Matter

    OpenAIRE

    Ouellette, Stephen M.; Seki, Ryoichi

    1997-01-01

    We calculate, in chiral perturbation theory, the change in the self-energy of decuplet baryons in nuclear matter. These self-energy shifts are relevant in studies of meson-nucleus scattering and of neutron stars. Our results are leading order in an expansion in powers of the ratio of characteristic momenta to the chiral symmetry-breaking scale (or the nucleon mass). Included are contact diagrams generated by 4-baryon operators, which were neglected in earlier studies for the $\\Delta$ isomulti...

  5. Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors.

    Science.gov (United States)

    Hong, Seung Hwan; Choi, Han-Yong

    2013-09-11

    We investigated the characteristics of spin fluctuation mediated superconductivity employing the Eliashberg formalism. The effective interaction between electrons was modeled in terms of the spin susceptibility measured by inelastic neutron scattering experiments on single crystal La(2-x)Sr(x)CuO4 superconductors. The diagonal self-energy and off-diagonal self-energy were calculated by solving the coupled Eliashberg equation self-consistently for the chosen spin susceptibility and tight-binding dispersion of electrons. The full momentum and frequency dependence of the self-energy is presented for optimally doped, overdoped, and underdoped LSCO cuprates in a superconductive state. These results may be compared with the experimentally deduced self-energy from ARPES experiments.

  6. Scalar Contribution to the Graviton Self-Energy During Inflation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sohyun [Univ. of Florida, Gainesville, FL (United States)

    2012-01-01

    We use dimensional regularization to evaluate the one loop contribution to the graviton self-energy from a massless, minimally coupled scalar on a locally de Sitter background. For noncoincident points our result agrees with the stress tensor correlators obtained recently by Perez-Nadal, Roura and Verdaguer. We absorb the ultraviolet divergences using the R2 and C2 counterterms first derived by ’t Hooft and Veltman, and we take the D = 4 limit of the finite remainder. The renormalized result is expressed as the sum of two transverse, 4th order differential operators acting on nonlocal, de Sitter invariant structure functions. In this form it can be used to quantum-correct the linearized Einstein equations so that one can study how the inflationary production of infrared scalars affects the propagation of dynamical gravitons and the force of gravity. We have seen that they have no effect on the propagation of dynamical gravitons. Our computation motivates a conjecture for the first correction to the vacuum state wave functional of gravitons. We comment as well on performing the same analysis for the more interesting contribution from inflationary gravitons, and on inferring one loop corrections to the force of gravity.

  7. Parton self-energies for general momentum-space anisotropy

    Science.gov (United States)

    Kasmaei, Babak S.; Strickland, Michael

    2018-03-01

    We introduce an efficient general method for calculating the self-energies, collective modes, and dispersion relations of quarks and gluons in a momentum-anisotropic high-temperature quark-gluon plasma. The method introduced is applicable to the most general classes of deformed anisotropic momentum distributions and the resulting self-energies are expressed in terms of a series of hypergeometric basis functions which are valid in the entire complex phase-velocity plane. Comparing to direct numerical integration of the self-energies, the proposed method is orders of magnitude faster and provides results with similar or better accuracy. To extend previous studies and demonstrate the application of the proposed method, we present numerical results for the parton self-energies and dispersion relations of partonic collective excitations for the case of an ellipsoidal momentum-space anisotropy. Finally, we also present, for the first time, the gluon unstable mode growth rate for the case of an ellipsoidal momentum-space anisotropy.

  8. Image charge models for accurate construction of the electrostatic self-energy of 3D layered nanostructure devices

    Science.gov (United States)

    Barker, John R.; Martinez, Antonio

    2018-04-01

    Efficient analytical image charge models are derived for the full spatial variation of the electrostatic self-energy of electrons in semiconductor nanostructures that arises from dielectric mismatch using semi-classical analysis. The methodology provides a fast, compact and physically transparent computation for advanced device modeling. The underlying semi-classical model for the self-energy has been established and validated during recent years and depends on a slight modification of the macroscopic static dielectric constants for individual homogeneous dielectric regions. The model has been validated for point charges as close as one interatomic spacing to a sharp interface. A brief introduction to image charge methodology is followed by a discussion and demonstration of the traditional failure of the methodology to derive the electrostatic potential at arbitrary distances from a source charge. However, the self-energy involves the local limit of the difference between the electrostatic Green functions for the full dielectric heterostructure and the homogeneous equivalent. It is shown that high convergence may be achieved for the image charge method for this local limit. A simple re-normalisation technique is introduced to reduce the number of image terms to a minimum. A number of progressively complex 3D models are evaluated analytically and compared with high precision numerical computations. Accuracies of 1% are demonstrated. Introducing a simple technique for modeling the transition of the self-energy between disparate dielectric structures we generate an analytical model that describes the self-energy as a function of position within the source, drain and gated channel of a silicon wrap round gate field effect transistor on a scale of a few nanometers cross-section. At such scales the self-energies become large (typically up to ~100 meV) close to the interfaces as well as along the channel. The screening of a gated structure is shown to reduce the self-energy

  9. Self energies of the electron and photon in the unified space field theory

    International Nuclear Information System (INIS)

    Duong Van Phi, Nguyen Mong Giao.

    1981-01-01

    Self energies of the electron and photon are calculated in the second approximation of perturbation theory. The formalism of the field theory of interaction in the unified 8-dimensional space is used. The calculations are free of divergence the unitary condition is fulfilled. It is shown that the ''naked'' and physical masses of a free electron are identical. A similar result is obtained for a free photon. Some other effects are discussed [ru

  10. Rho meson self-energy and dielectron emissivity in an isospin-asymmetric pion medium

    International Nuclear Information System (INIS)

    Gulamov, T.I.; Titov, A.I.; Forschungszentrum Rossendorf e.V.; Kaempfer, B.; Technische Univ., Dresden

    1995-06-01

    The ρ meson self-energy in an isospin asymmetric pion gas at finite temperature and charged-pion chemical potential is evaluated. We utilize a conventional effective π-ρ Lagrangian and the functional integral representation of the partition function in the second order in the ρππ coupling constant. We analyze the gauge invariant rho meson polarization operator and its dependence on the invariant mass M and spatial momentum vertical stroke pvertical stroke of the ρ meson. The pole positions and the values of the imaginary parts of the self-energy for different polarization states have different functional dependences on M and vertical stroke pvertical stroke . The corresponding dielectron rate (calculated from the imaginary part of the polarization operators) shows a distinctive asymmetry when the momentum t=p + -p - is perpendicular or parallel to p, where p ± are the momenta of the electron pair. (orig.)

  11. ρ-meson self-energy and dielectron emissivity in an isospin-asymmetric pion medium

    International Nuclear Information System (INIS)

    Titov, A.I.; Gulamov, T.I.; Kaempfer, B.

    1996-01-01

    The ρ-meson self-energy in an isospin-asymmetric pion gas at finite temperature and charged-pion chemical potential is evaluated. We utilize a conventional effective π-ρ Lagrangian and the functional integral representation of the partition function in the second order in the ρππ coupling constant. We analyze the ρ-meson polarization operator and its dependence on the invariant mass M and spatial momentum parallel p parallel of the ρ meson. The pole positions and the values of the imaginary parts of the self-energy for different polarization states have different functional dependences on M and parallel p parallel. The corresponding dielectron rate (calculated from the imaginary part of the in-medium ρ-meson propagator) shows a distinctive asymmetry when the momentum t=p + -p - is perpendicular or parallel to p, where p ± are the e ± momenta of the electron pair. copyright 1996 The American Physical Society

  12. Analytic properties of finite-temperature self-energies

    International Nuclear Information System (INIS)

    Weldon, H. Arthur

    2002-01-01

    The analytic properties in the energy variable k 0 of finite-temperature self-energies are investigated. A typical branch cut results from n particles being emitted into the heat bath and n ' being absorbed from the heat bath. There are three main results: First, in addition to the branch points at which the cuts terminate, there are also branch points attached to the cuts along their length. Second, branch points at k 0 =±k are ubiquitous and for massive particles they are essential singularities. Third, in a perturbative expansion using free particle propagators or in a resummed expansion in which the propagator pole occurs at a real energy, the self-energy will have a branch point at the pole location

  13. Projection operator approach to the self-energy

    International Nuclear Information System (INIS)

    Capuzzi, F.; Mahaux, C.

    1996-01-01

    Feshbach close-quote s projection operator formalism is extended to the description of the self-energy. This necessitates the introduction of open-quote open-quote extended close-quote close-quote projection operators. They act within an open-quote open-quote extended close-quote close-quote Hilbert space in which the number of nucleons is not fixed. The compact formula derived for the self-energy is formally similar to Feshbach close-quote s original expression of the open-quote open-quote generalized close-quote close-quote optical-model potential. The theory is formulated in the nuclear case, but it also applies to atomic systems. It covers both the open-quote open-quote retarded close-quote close-quote and the open-quote open-quote time-ordered close-quote close-quote Green close-quote s functions, and the open-quote open-quote proper close-quote close-quote and open-quote open-quote improper close-quote close-quote self-energies. It is first worked out in a stationary formalism, in order to better exhibit its analogy with Feshbach close-quote s original theory of the generalized optical-model potential. The main results are then also derived in a time-dependent framework. It is shown that, in finite systems, Dyson close-quote s equation does not uniquely determine the self-energy, in contrast to common assumption. However, the difference between the various possibilities has little practical consequence. We exhibit the relationship between the present approach and a recent open-quote open-quote configuration interaction formulation of the Dyson equation.close-quote close-quote Contact is also established with the open-quote open-quote linked-cluster close-quote close-quote perturbation expansion of the self-energy in powers of the strength of the nucleon endash nucleon interaction. Copyright copyright 1996 Academic Press, Inc

  14. Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)

    2008-12-15

    Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.

  15. Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

    International Nuclear Information System (INIS)

    Cheng Ming; Su Wupei

    2008-01-01

    Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling

  16. Superconductivity induced by doping Rh in CaFe2-xRhxAs2

    International Nuclear Information System (INIS)

    Qi Yanpeng; Wang Lei; Gao Zhaoshun; Wang Dongliang; Zhang Xianping; Wang Chunlei; Yao Chao; Ma Yanwei

    2011-01-01

    In this paper, we report the synthesis of iron-based superconductors CaFe 2-x Rh x As 2 using a one-step solid state reaction method that crystallizes in the ThCr 2 Si 2 -type structure with a space group I4/mmm. The systematic evolution of the lattice constants demonstrates that the Fe ions are successfully replaced by the Rh. By increasing the doping content of Rh, the spin-density-wave (SDW) transition in the parent compound is suppressed and superconductivity emerges. The maximum superconducting transition temperature is found at 18.5 K with a doping level of x=0.15. The temperature dependence of dc magnetization confirms superconducting transitions at around 15 K. The general phase diagram was obtained and found to be similar to the case of the Rh-doping Sr122 system. Our results explicitly demonstrate the feasibility of inducing superconductivity in Ca122 compounds by higher d-orbital electron doping; however, different Rh-doping effects between FeAs122 compounds and FeAs1111 systems still remains an open question.

  17. Closed expressions for specific massive multiloop self-energy integrals

    International Nuclear Information System (INIS)

    Berends, F.A.; Boehm, M.; Buza, M.; Scharf, R.

    1994-01-01

    In this paper the class of N loop massive scalar self-energy diagrams with N + 1 propagators is studied in an arbitrary number of dimensions. As it is known these integrals cannot be expressed in terms of polylogarithms. Here it is shown, however, that they can be described by generalized hypergeometric functions of several variables, namely Laricella functions. These results represent previous small and large momentum expansions in closed form. Numerical comparisons for the finite part in four dimensions with a two-dimensional integral representation show good agreement. (orig.)

  18. Quark self-energy beyond the mean field at finite temperature

    International Nuclear Information System (INIS)

    Zhuang, P.

    1995-01-01

    The Nambu--Jona-Lasinio model, an effective low-energy model of QCD, is extended to the next to the leading order in the 1/N c expansion at finite temperature and density. The contributions to the quark self-energy and the constituent quark mass from the meson dressing are considered in a perturbative approach about the mean field. In particular, the temperature dependence of the quark mass is shown numerically at zero chemical potential. The correction to the quark mass from the meson dressing amounts to 20% compared to the result of the leading order at low temperature, and rapidly approaches zero at high temperature

  19. Induced self-energy on a static scalar charged particle in the spacetime of a global monopole with finite core

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Denis; Freitas, Umbelino; Mello, Eugenio Bezerra de [Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba (IFPB), Joao Pessoa, PB (Brazil); Universidade Federal da Paraiba (IFPB), PB (Brazil)

    2011-07-01

    Full text: Global monopoles are heavy spherically symmetric topological objects which may have been formed by the vacuum phase transition in the early universe after Planck time. Although the global monopole was first introduced by Sokolov and Starobinsky, its gravitational effects have been analyzed by Barriola and Vilenkin. We analyze the induced self-energy and self-force on a scalar point-like charged test particle placed at rest in the spacetime of a global monopole admitting a general spherically symmetric inner structure to it. In order to develop this analysis we calculate the three-dimensional Green function associated with this physical system. We explicitly show that for points outside the monopoles core the scalar self-energy presents two distinct contributions. The first one is induced by the non-trivial topology of the global monopole considered as a point-like defect and the second is a correction induced by the non-vanishing inner structure attributed to it. For points inside the monopole, the self-energy also present a similar structure, where now the first contribution depends on the geometry of the spacetime inside. As illustrations of the general procedure adopted, two specific models, namely flower-pot and the ball-point pen, are considered for the region inside. For these two different situations, we were able to obtain exact expressions for the self-energies and self-forces in the regions outside and inside the global monopole. (author)

  20. Induced self-energy on a static scalar charged particle in the spacetime of a global monopole with finite core

    International Nuclear Information System (INIS)

    Barbosa, Denis; Freitas, Umbelino; Mello, Eugenio Bezerra de

    2011-01-01

    Full text: Global monopoles are heavy spherically symmetric topological objects which may have been formed by the vacuum phase transition in the early universe after Planck time. Although the global monopole was first introduced by Sokolov and Starobinsky, its gravitational effects have been analyzed by Barriola and Vilenkin. We analyze the induced self-energy and self-force on a scalar point-like charged test particle placed at rest in the spacetime of a global monopole admitting a general spherically symmetric inner structure to it. In order to develop this analysis we calculate the three-dimensional Green function associated with this physical system. We explicitly show that for points outside the monopoles core the scalar self-energy presents two distinct contributions. The first one is induced by the non-trivial topology of the global monopole considered as a point-like defect and the second is a correction induced by the non-vanishing inner structure attributed to it. For points inside the monopole, the self-energy also present a similar structure, where now the first contribution depends on the geometry of the spacetime inside. As illustrations of the general procedure adopted, two specific models, namely flower-pot and the ball-point pen, are considered for the region inside. For these two different situations, we were able to obtain exact expressions for the self-energies and self-forces in the regions outside and inside the global monopole. (author)

  1. Scalar self-energy for a charged particle in global monopole spacetime with a spherical boundary

    International Nuclear Information System (INIS)

    De Mello, E R Bezerra; Saharian, A A

    2012-01-01

    We analyze combined effects of the geometry produced by a global monopole and a concentric spherical boundary on the self-energy of a point-like scalar charged test particle at rest. We assume that the boundary is outside the monopole's core with a general spherically symmetric inner structure. An important quantity to this analysis is the three-dimensional Green function associated with this system. For both Dirichlet and Neumann boundary conditions obeyed by the scalar field on the sphere, the Green function presents a structure that contains contributions due to the background geometry of the spacetime and the boundary. Consequently, the corresponding induced scalar self-energy also presents a similar structure. For points near the sphere, the boundary-induced part dominates and the self-force is repulsive/attractive with respect to the boundary for Dirichlet/Neumann boundary condition. In the region outside the sphere at large distances from it, the boundary-free part in the self-energy dominates and the corresponding self-force can be either attractive or repulsive with dependence of the curvature coupling parameter for scalar field. In particular, for the minimal coupling we show the presence of a stable equilibrium point for the Dirichlet boundary condition. In the region inside the sphere, the nature of the self-force depends on the specific model for the monopole's core. As illustrations of the general procedure adopted, we shall consider two distinct models, namely the flower-pot and the ballpoint-pen ones. (paper)

  2. Self-energy-modified Poisson-Nernst-Planck equations: WKB approximation and finite-difference approaches.

    Science.gov (United States)

    Xu, Zhenli; Ma, Manman; Liu, Pei

    2014-07-01

    We propose a modified Poisson-Nernst-Planck (PNP) model to investigate charge transport in electrolytes of inhomogeneous dielectric environment. The model includes the ionic polarization due to the dielectric inhomogeneity and the ion-ion correlation. This is achieved by the self energy of test ions through solving a generalized Debye-Hückel (DH) equation. We develop numerical methods for the system composed of the PNP and DH equations. Particularly, toward the numerical challenge of solving the high-dimensional DH equation, we developed an analytical WKB approximation and a numerical approach based on the selective inversion of sparse matrices. The model and numerical methods are validated by simulating the charge diffusion in electrolytes between two electrodes, for which effects of dielectrics and correlation are investigated by comparing the results with the prediction by the classical PNP theory. We find that, at the length scale of the interface separation comparable to the Bjerrum length, the results of the modified equations are significantly different from the classical PNP predictions mostly due to the dielectric effect. It is also shown that when the ion self energy is in weak or mediate strength, the WKB approximation presents a high accuracy, compared to precise finite-difference results.

  3. Local self-energies for V and Pd emergent from a nonlocal LDA+FLEX implementation

    Science.gov (United States)

    Savrasov, Sergey Y.; Resta, Giacomo; Wan, Xiangang

    2018-04-01

    In the spirit of recently developed LDA+U and LDA+DMFT methods, we implement a combination of density functional theory in its local density approximation (LDA) with a k - and ω -dependent self-energy found from diagrammatic fluctuational exchange (FLEX) approximation. The active Hilbert space here is described by the correlated subset of electrons which allows one to tremendously reduce the sizes of the matrices needed to represent charge and spin susceptibilities. The method is perturbative in nature but accounts for both bubble and ladder diagrams and accumulates the physics of momentum-resolved spin fluctuations missing in such popular approach as GW. As an application, we study correlation effects on band structures in V and Pd. The d -electron self-energies emergent from this calculation are found to be remarkably k independent. However, when we compare our calculated electronic mass enhancements against LDA+DMFT, we find that for the longstanding problem of spin fluctuations in Pd, LDA+FLEX delivers a better agreement with experiment, although this conclusion depends on a particular value of the Hubbard U used in the simulation. We also discuss outcomes of a recently proposed combination of k -dependent FLEX with dynamical mean-field theory (DMFT).

  4. Perturbative expansions from Monte Carlo simulations at weak coupling: Wilson loops and the static-quark self-energy

    Science.gov (United States)

    Trottier, H. D.; Shakespeare, N. H.; Lepage, G. P.; MacKenzie, P. B.

    2002-05-01

    Perturbative coefficients for Wilson loops and the static-quark self-energy are extracted from Monte Carlo simulations at weak coupling. The lattice volumes and couplings are chosen to ensure that the lattice momenta are all perturbative. Twisted boundary conditions are used to eliminate the effects of lattice zero modes and to suppress nonperturbative finite-volume effects due to Z(3) phases. Simulations of the Wilson gluon action are done with both periodic and twisted boundary conditions, and over a wide range of lattice volumes (from 34 to 164) and couplings (from β~9 to β~60). A high precision comparison is made between the simulation data and results from finite-volume lattice perturbation theory. The Monte Carlo results are shown to be in excellent agreement with perturbation theory through second order. New results for third-order coefficients for a number of Wilson loops and the static-quark self-energy are reported.

  5. Replacing leads by self-energies using non-equilibrium Green's functions

    International Nuclear Information System (INIS)

    Michael, Fredrick; Johnson, M.D.

    2003-01-01

    Open quantum systems consist of semi-infinite leads which transport electrons to and from the device of interest. We show here that within the non-equilibrium Green's function technique for continuum systems, the leads can be replaced by simple c-number self-energies. Our starting point is an approach for continuum systems developed by Feuchtwang. The reformulation developed here is simpler to understand and carry out than the somewhat unwieldly manipulations typical in the Feuchtwang method. The self-energies turn out to have a limited variability: the retarded self-energy Σ r depends on the arbitrary choice of internal boundary conditions, but the non-equilibrium self-energy or scattering function Σ which determines transport is invariant for a broad class of boundary conditions. Expressed in terms of these self-energies, continuum non-equilibrium transport calculations take a particularly simple form similar to that developed for discrete systems

  6. Imaginary part of the next-to-leading-order static gluon self-energy in an anisotropic plasma

    International Nuclear Information System (INIS)

    Carrington, M. E.; Rebhan, A.

    2009-01-01

    Using hard-loop (HL) effective theory for an anisotropic non-Abelian plasma, which even in the static limit involves nonvanishing HL vertices, we calculate the imaginary part of the static next-to-leading-order gluon self-energy in the limit of a small anisotropy and with external momentum parallel to the anisotropy direction. At leading order, the static propagator has spacelike poles corresponding to plasma instabilities. On the basis of a calculation using bare vertices, it has been conjectured that, at next-to-leading order, the static gluon self-energy acquires an imaginary part which regulates these spacelike poles. We find that the one-loop resummed expression taken over naively from the imaginary-time formalism does yield a nonvanishing imaginary part even after including all HL vertices. However, this result is not correct. Starting from the real-time formalism, which is required in a nonequilibrium situation, we construct a resummed retarded HL propagator with correct causality properties and show that the static limit of the retarded one-loop-resummed gluon self-energy is real. This result is also required for the time-ordered propagator to exist at next-to-leading order.

  7. Perturbation approach to the self-energy of non-S hydrogenic states

    International Nuclear Information System (INIS)

    Le Bigot, Eric-Olivier; Jentschura, Ulrich D.; Mohr, Peter J.; Indelicato, Paul; Soff, Gerhard

    2003-01-01

    We present results on the self-energy correction to the energy levels of hydrogen and hydrogenlike ions. The self-energy represents the largest QED correction to the relativistic (Dirac-Coulomb) energy of a bound electron. We focus on the perturbation expansion of the self-energy of non-S states, and provide estimates of the so-called A 60 perturbation coefficient, which can be viewed as a relativistic Bethe logarithm. Precise values of A 60 are given for many P, D, F, and G states, while estimates are given for other states. These results can be used in high-precision spectroscopy experiments in hydrogen and hydrogenlike ions. They yield the best available estimate of the self-energy correction of many atomic states

  8. General Retarded Contact Self-energies in and beyond the Non-equilibrium Green's Functions Method

    Science.gov (United States)

    Kubis, Tillmann; He, Yu; Andrawis, Robert; Klimeck, Gerhard

    2016-03-01

    Retarded contact self-energies in the framework of nonequilibrium Green's functions allow to model the impact of lead structures on the device without explicitly including the leads in the actual device calculation. Most of the contact self-energy algorithms are limited to homogeneous or periodic, semi-infinite lead structures. In this work, the complex absorbing potential method is extended to solve retarded contact self-energies for arbitrary lead structures, including irregular and randomly disordered leads. This method is verified for regular leads against common approaches and on physically equivalent, but numerically different irregular leads. Transmission results on randomly alloyed In0.5Ga0.5As structures show the importance of disorder in the leads. The concept of retarded contact self-energies is expanded to model passivation of atomically resolved surfaces without explicitly increasing the device's Hamiltonian.

  9. Multiple scattering expansion of the self-energy at finite temperature

    International Nuclear Information System (INIS)

    Jeon, S.; Ellis, P.J.

    1998-01-01

    An often used rule that the thermal correction to the self-energy is the thermal phase-space times the forward scattering amplitude from target particles is shown to be the leading term in an exact multiple scattering expansion. Starting from imaginary-time finite-temperature field theory, a rigorous expansion for the retarded self-energy is derived. The relationship to the thermodynamic potential is briefly discussed. copyright 1998 The American Physical Society

  10. Multiple Scattering Expansion of the Self-Energy at Finite Temperature

    OpenAIRE

    Jeon, Sangyong; Ellis, Paul J.

    1998-01-01

    An often used rule that the thermal correction to the self-energy is the thermal phase-space times the forward scattering amplitude from target particles is shown to be the leading term in an exact multiple scattering expansion. Starting from imaginary-time finite-temperature field theory, a rigorous expansion for the retarded self-energy is derived. The relationship to the thermodynamic potential is briefly discussed.

  11. Dispersion relations for the self-energy in noncommutative field theories

    International Nuclear Information System (INIS)

    Brandt, F.T.; Das, Ashok; Frenkel, J.

    2002-01-01

    We study the IR-UV connection in noncommutative φ 3 theory as well as in noncommutative QED from the point of view of the dispersion relation for self-energy. We show that, although the imaginary part of the self-energy is well behaved as the parameter of noncommutativity vanishes, the real part becomes divergent as a consequence of the high energy behavior of the dispersion integral. Some other interesting features that arise from this analysis are also briefly discussed

  12. Perturbative expansions from Monte Carlo simulations at weak coupling: Wilson loops and the static-quark self-energy

    International Nuclear Information System (INIS)

    Trottier, H.D.; Shakespeare, N.H.; Lepage, G.P.; Mackenzie, P.B.

    2002-01-01

    Perturbative coefficients for Wilson loops and the static-quark self-energy are extracted from Monte Carlo simulations at weak coupling. The lattice volumes and couplings are chosen to ensure that the lattice momenta are all perturbative. Twisted boundary conditions are used to eliminate the effects of lattice zero modes and to suppress nonperturbative finite-volume effects due to Z(3) phases. Simulations of the Wilson gluon action are done with both periodic and twisted boundary conditions, and over a wide range of lattice volumes (from 3 4 to 16 4 ) and couplings (from β≅9 to β≅60). A high precision comparison is made between the simulation data and results from finite-volume lattice perturbation theory. The Monte Carlo results are shown to be in excellent agreement with perturbation theory through second order. New results for third-order coefficients for a number of Wilson loops and the static-quark self-energy are reported

  13. Calculation of β-decay rates in a relativistic model with momentum-dependent self-energies

    International Nuclear Information System (INIS)

    Marketin, T.; Vretenar, D.; Ring, P.

    2007-01-01

    The relativistic proton-neutron quasiparticle random phase approximation (PN-RQRPA) is applied in the calculation of β-decay half-lives of neutron-rich nuclei in the Z≅28 and Z≅50 regions. The study is based on the relativistic Hartree-Bogoliubov calculation of nuclear ground states, using effective Lagrangians with density-dependent meson-nucleon couplings, and also extended by the inclusion of couplings between the isoscalar meson fields and the derivatives of the nucleon fields. This leads to a linear momentum dependence of the scalar and vector nucleon self-energies. The residual QRPA interaction in the particle-hole channel includes the π+ρ exchange plus a Landau-Migdal term. The finite-range Gogny interaction is employed in the T=1 pairing channel, and the model also includes a proton-neutron particle-particle interaction. The results are compared with available data, and it is shown that an extension of the standard relativistic mean-field framework to include momentum-dependent nucleon self-energies naturally leads to an enhancement of the effective (Landau) nucleon mass, and thus to an improved PN-QRPA description of β - -decay rates

  14. Two-Loop Self-Energy Correction in a Strong Coulomb Nuclear Field

    International Nuclear Information System (INIS)

    Yerokhin, V.A.; Indelicato, P.; Shabaev, V.M.

    2005-01-01

    The two-loop self-energy correction to the ground-state energy levels of hydrogen-like ions with nuclear charges Z ≥ 10 is calculated without the Zα expansion, where α is the fine-structure constant. The data obtained are compared with the results of analytical calculations within the Zα expansion; significant disagreement with the analytical results of order α 2 (Zα) 6 has been found. Extrapolation is used to obtain the most accurate value for the two-loop self-energy correction for the 1s state in hydrogen

  15. Phonon self-energy corrections to non-zero wavevector phonon modes in single-layer graphene

    Science.gov (United States)

    Araujo, Paulo; Mafra, Daniela; Sato, Kentaro; Saito, Richiiro; Kong, Jing; Dresselhaus, Mildred

    2012-02-01

    Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q = 0) wave-vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene (1LG) in the frequency range from 2350 to 2750 cm-1, which shows the G* and the G'-band features originating from a double-resonant Raman process with q 0. The observed phonon renormalization effects are different from what is observed for the zone-center q = 0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with non-zero wave-vectors (q 0) in 1LG in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q = 0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G* Raman feature at 2450 cm-1 to include the iTO+LA combination modes with q 0 and the 2iTO overtone modes with q = 0, showing both to be associated with wave-vectors near the high symmetry point K in the Brillouin zone.

  16. Phonon Self-Energy Corrections to Nonzero Wave-Vector Phonon Modes in Single-Layer Graphene

    Science.gov (United States)

    Araujo, P. T.; Mafra, D. L.; Sato, K.; Saito, R.; Kong, J.; Dresselhaus, M. S.

    2012-07-01

    Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q=0) wave vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene originating from a double-resonant Raman process with q≠0. The observed phonon renormalization effects are different from what is observed for the zone-center q=0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with nonzero wave vectors (q≠0) in single-layer graphene in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q=0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G⋆ Raman feature at 2450cm-1 to include the iTO+LA combination modes with q≠0 and also the 2iTO overtone modes with q=0, showing both to be associated with wave vectors near the high symmetry point K in the Brillouin zone.

  17. Numerical integration for ab initio many-electron self energy calculations within the GW approximation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fang, E-mail: fliu@lsec.cc.ac.cn [School of Statistics and Mathematics, Central University of Finance and Economics, Beijing 100081 (China); Lin, Lin, E-mail: linlin@math.berkeley.edu [Department of Mathematics, University of California, Berkeley, CA 94720 (United States); Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Vigil-Fowler, Derek, E-mail: vigil@berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lischner, Johannes, E-mail: jlischner597@gmail.com [Department of Physics, University of California, Berkeley, CA 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kemper, Alexander F., E-mail: afkemper@lbl.gov [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sharifzadeh, Sahar, E-mail: ssharifz@bu.edu [Department of Electrical and Computer Engineering and Division of Materials Science and Engineering, Boston University, Boston, MA 02215 (United States); Jornada, Felipe H. da, E-mail: jornada@berkeley.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Deslippe, Jack, E-mail: jdeslippe@lbl.gov [NERSC, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Yang, Chao, E-mail: cyang@lbl.gov [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); and others

    2015-04-01

    We present a numerical integration scheme for evaluating the convolution of a Green's function with a screened Coulomb potential on the real axis in the GW approximation of the self energy. Our scheme takes the zero broadening limit in Green's function first, replaces the numerator of the integrand with a piecewise polynomial approximation, and performs principal value integration on subintervals analytically. We give the error bound of our numerical integration scheme and show by numerical examples that it is more reliable and accurate than the standard quadrature rules such as the composite trapezoidal rule. We also discuss the benefit of using different self energy expressions to perform the numerical convolution at different frequencies.

  18. Krylov subspace method for evaluating the self-energy matrices in electron transport calculations

    DEFF Research Database (Denmark)

    Sørensen, Hans Henrik Brandenborg; Hansen, Per Christian; Petersen, D. E.

    2008-01-01

    We present a Krylov subspace method for evaluating the self-energy matrices used in the Green's function formulation of electron transport in nanoscale devices. A procedure based on the Arnoldi method is employed to obtain solutions of the quadratic eigenvalue problem associated with the infinite...... calculations. Numerical tests within a density functional theory framework are provided to validate the accuracy and robustness of the proposed method, which in most cases is an order of magnitude faster than conventional methods.......We present a Krylov subspace method for evaluating the self-energy matrices used in the Green's function formulation of electron transport in nanoscale devices. A procedure based on the Arnoldi method is employed to obtain solutions of the quadratic eigenvalue problem associated with the infinite...

  19. Two-loop finiteness of self-energies in higher-derivative SQED3

    Directory of Open Access Journals (Sweden)

    E.A. Gallegos

    2015-09-01

    Full Text Available In the N=1 superfield formalism, two higher-derivative kinetic operators (Lee–Wick operators are implemented into the standard three dimensional supersymmetric quantum electrodynamics (SQED3 for improving its ultraviolet behavior. It is shown in particular that the ghosts associated with these Lee–Wick operators allow to remove all ultraviolet divergences in the scalar and gauge self-energies at two-loop level.

  20. All orders Boltzmann collision term from the multiple scattering expansion of the self-energy

    International Nuclear Information System (INIS)

    Fillion-Gourdeau, F.; Gagnon, J.-S.; Jeon, S.

    2007-01-01

    We summarize our main findings in deriving the Boltzmann collision term from the Kadanoff-Baym relativistic transport equation and the multiple scattering expansion of the self-energy within a quasi-particle approximation. Our collision term is valid to all orders in perturbation theory and contains processes with any number of participating particles. This work completes a program initiated by Carrington and Mrowczynski and developed further by present authors and Weinstock in recent literature

  1. Divergence of the quark self-energy in the second quantized chiral bag model

    International Nuclear Information System (INIS)

    Oset, E.

    1983-01-01

    When summing over the intermediate quark states of a spherical cavity, the quark self-energy of the chiral bag model, in lowest order of the pion coupling, is shown to generate a series of terms, each one growing linearly with the angular variable kappa. However, there is a cancellation between terms for different kappa, which finally leads to an overall linearly divergent series. (orig.)

  2. Exact self-energy of the many-body problem from conserving approximations

    International Nuclear Information System (INIS)

    Takada, Y.

    1995-01-01

    A procedure is proposed to obtain the exact self-energy in the many-body problem. This algorithm is based on the formal analysis to reach the exact theory by repeated applications of an operator F to an arbitrarily chosen input self-energy represented as a functional of the dressed Green's function. The operator F is so defined that the microscopic conservation law for particle number is satisfied. The rigorous self-energy is obtained by the solution of an eigenfunction of F. Particular attention is paid to the relation between the present procedure and the Baym-Kadanoff framework of conserving approximations. By simplifying the procedure in F with use of the generalized Ward identity, we suggest a practical method to implement this algorithm rather easily in actual systems. In order to suggest future directions to improve on this practical method, the recently developed mean-field theory for the Hubbard model in the limit of high spatial dimensions is also discussed in the context of our theory

  3. Internal gravity, self-energy, and disruption of comets and asteroids

    Science.gov (United States)

    Dobrovolskis, Anthony R.; Korycansky, D. G.

    2018-03-01

    The internal gravity and self-gravitational energy of a comet, asteroid, or small moon have applications to their geophysics, including their formation, evolution, cratering, and disruption, the stresses and strains inside such objects, sample return, eventual asteroid mining, and planetary defense strategies for potentially hazardous objects. This paper describes the relation of an object's self-energy to its collisional disruption energy, and shows how to determine an object's self-energy from its internal gravitational potential. Any solid object can be approximated to any desired accuracy by a polyhedron of sufficient complexity. An analytic formula is known for the gravitational potential of any homogeneous polyhedron, but it is widely believed that this formula applies only on the surface or outside of the object. Here we show instead that this formula applies equally well inside the object. We have used these formulae to develop a numerical code which evaluates the self-energy of any homogeneous polyhedron, along with the gravitational potential and attraction both inside and outside of the object, as well as the slope of its surface. Then we use our code to find the internal, external, and surface gravitational fields of the Platonic solids, asteroid (216) Kleopatra, and comet 67P/Churyumov-Gerasimenko, as well as their surface slopes and their self-gravitational energies. We also present simple spherical, ellipsoidal, cuboidal, and duplex models of Kleopatra and comet 67P, and show how to generalize our methods to inhomogeneous objects and magnetic fields. At present, only the self-energies of spheres, ellipsoids, and cuboids (boxes) are known analytically (or semi-analytically). The Supplementary Material contours the central potential and self-energy of homogeneous ellipsoids and cuboids of all aspect ratios, and also analytically the self-gravitational energy of a "duplex" consisting of two coupled spheres. The duplex is a good model for "contact binary

  4. General Retarded Contact Self-energies in and beyond the Non-equilibrium Green's Functions Method

    International Nuclear Information System (INIS)

    Kubis, Tillmann; He, Yu; Andrawis, Robert; Klimeck, Gerhard

    2016-01-01

    Retarded contact self-energies in the framework of nonequilibrium Green's functions allow to model the impact of lead structures on the device without explicitly including the leads in the actual device calculation. Most of the contact self-energy algorithms are limited to homogeneous or periodic, semi-infinite lead structures. In this work, the complex absorbing potential method is extended to solve retarded contact self-energies for arbitrary lead structures, including irregular and randomly disordered leads. This method is verified for regular leads against common approaches and on physically equivalent, but numerically different irregular leads. Transmission results on randomly alloyed In 0.5 Ga 0.5 As structures show the importance of disorder in the leads. The concept of retarded contact self-energies is expanded to model passivation of atomically resolved surfaces without explicitly increasing the device's Hamiltonian. (paper)

  5. Skeleton series and multivaluedness of the self-energy functional in zero space-time dimensions

    Science.gov (United States)

    Rossi, Riccardo; Werner, Félix

    2015-12-01

    Recently, Kozik, Ferrero and Georges discovered numerically that for a family of fundamental models of interacting fermions, the self-energy {{Σ }}[G] is a multi-valued functional of the fully dressed single-particle propagator G, and that the skeleton diagrammatic series {{{Σ }}}{{bold}}[G] converges to the wrong branch above a critical interaction strength. We consider the zero space-time dimensional case, where the same mathematical phenomena appear from elementary algebra. We also find a similar phenomenology for the fully bold formalism built on the fully dressed single-particle propagator and pair propagator.

  6. Field theory reformulated without self-energy parts: the dressing operator

    International Nuclear Information System (INIS)

    Haan, M. de

    2004-01-01

    The reformulation of field theory for avoiding self-energy parts in the dynamical evolution has been applied successfully in the framework of the Lee model [Ann. Phys. 311 (2004) 314], enabling a kinetic extension of the description. The basic ingredient is the recognition of these self-energy parts [Trends Stat. Phys. 3 (2000) 115]. The original reversible description is embedded in the new one and appears now as a restricted class of initial conditions [Progr. Theor. Phys. 109 (2003) 881]. This program is realized here in the reduced formalism for a scalar field, interacting with a two-level atom, beyond the usual rotating wave approximation. The kinetic evolution operator, previously surmised [Physica A 171 (1991) 159], is here derived from first principles, justifying the usual practice in optics where the common use of the so-called pole approximation [Atoms in Electromagnetic Fields, 1994, 119] should no longer be viewed as an approximation but as an alternative description in the appropriate formalism. That model illustrates how some dressing of the atomic levels (and vertices), through an appropriate operator, finds its place naturally into the new formalism since the bare and dressed ground states do no longer coincide. Moreover, finite velocity for field propagation is now possible in all cases, without the presence of precursors for multiple detections

  7. Self-energies, renormalization factor, Luttinger sum rule and quasiparticle structure of the Hubbard systems

    International Nuclear Information System (INIS)

    Lopez-Aguilar, F.; Costa-Quintana, J.

    1992-01-01

    In this paper, the authors give a method for obtaining the renormalized electronic structure of the Hubbard systems. The first step is the determination of the self-energy beyond the Hartree-Fock approximation. This self-energy is constructed from several dielectric response functions. The second step is the determination of the quasiparticle band structure calculation which is performed from an appropriate modification of the augmented plane wave method. The third step consists in the determination of the renormalized density of states deduced from the spectral functions. The analysis of the renormalized density of states of the strongly correlated systems leads to the conclusion that there exist three types of resonances in their electronic structures, the lower energy resonances (LER), the middle energy resonances (MER) and the upper energy resonances (UER). In addition, the authors analyze the conditions for which the Luttinger theorem is satisfied. All of these questions are determined in a characteristic example which allows to test the theoretical method

  8. The two-photon self-energy and other QED radiative corrections

    International Nuclear Information System (INIS)

    Zschocke, S.

    2001-07-01

    One of the main issues in current nuclear physics is the precise measurement of the Lamb shift of strongly bound electrons in quantum electrodynamic (QED) tests in strong fields in highly charged ions. The currently performed high-precision measurements require extreme accuracy in the theoretical calculation of Lamb shift. This requires consideration of all α and α 2 order QED corrections as well as of precisely all orders in Zα. In the past years most of these QED corrections have been calculated both in 1st order and in 2nd order interference theory. As yet however, it has not been possible to assess the contribution of the two-photon self-energy, which has therefore been the greatest uncertainty factor in predicting Lamb shift in hydrogen-like systems. This study examines the contribution of these processes to Lamb shift. It also provides the first ever derivation of renormalized terms of two-photon vacuum polarisation and self-energy vacuum polarisation. Until now it has only been possible to evaluate these contributions by way of an Uehling approximation [de

  9. Unraveling the interlayer-related phonon self-energy renormalization in bilayer graphene.

    Science.gov (United States)

    Araujo, Paulo T; Mafra, Daniela L; Sato, Kentaro; Saito, Riichiro; Kong, Jing; Dresselhaus, Mildred S

    2012-01-01

    In this letter, we present a step towards understanding the bilayer graphene (2LG) interlayer (IL)-related phonon combination modes and overtones as well as their phonon self-energy renormalizations by using both gate-modulated and laser-energy dependent inelastic scattering spectroscopy. We show that although the IL interactions are weak, their respective phonon renormalization response is significant. Particularly special, the IL interactions are mediated by Van der Waals forces and are fundamental for understanding low-energy phenomena such as transport and infrared optics. Our approach opens up a new route to understanding fundamental properties of IL interactions which can be extended to any graphene-like material, such as MoS₂, WSe₂, oxides and hydroxides. Furthermore, we report a previously elusive crossing between IL-related phonon combination modes in 2LG, which might have important technological applications.

  10. The problem of infinite self-energy in electrodynamics and gravitation

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, K P; Sivaram, C [Indian Inst. of Science, Bangalore. Div. of Physics and Mathematical Sciences

    1975-02-01

    The appearance of infinities in the self-energies of point particles in both classical and quantum electrodynamics has been a persistent problem for the last several decades. This problem is discussed at length in relation to the Newtonian theory of gravitation and the modern (relativity) theory on gravitation. Gravitational contraction and the mass and radius of the electron are treated in detail. The spacetime properties around the Schwarzchild radius of the electron are modified to explain the divergences. The quantum gravitational mass and the quantum gravitational length are mentioned. It is pointed out that the out-off at the Schwarzchild radius applies not only to photon but also to the virtual quanta of all fields with which the particle interacts. Arguments are extended to explain the gravitational interactions of the proton. The interactions of the hadrons through f-gravity are explained. Recent work on renormalisibility (i.e. removal of divergences) of quantum gravitation are mentioned.

  11. Self-energy operator for an electron in an external Coulomb potential. II

    International Nuclear Information System (INIS)

    Hostler, L.

    1988-01-01

    Relativistic Coulomb Sturmian matrix elements of the operator Oequivalentln(1-rho)/rho, rho = -[πx(1+iσ)xπ]/m 2 , in terms of which the self-energy operator for an electron in an external Coulomb potential has been expressed, are studied. The operator O is dealt with on a term by term basis in a Sturmian expansion. Each term of the Sturmian expansion is separated into a part whose matrix elements are analytic functions of Zα, plus a remainder evaluated in closed form by use of the Cauchy residue theorem. All ignorance about the matrix element of the general term in the Sturmian expansion of O is thereby placed entirely in the analytic part, for which an explicit integral representation is derived

  12. On-shell gauge-parameter independence of contributions to electroweak quark self-energies

    International Nuclear Information System (INIS)

    Ahmady, M.R.; Elias, V.; Mendel, R.R.; Scadron, M.D.; Steele, T.

    1989-01-01

    We allow an external condensate to enter standard SU(2) x U(1) electroweak theory via the vacuum expectation value , as in QCD sum-rule applications. For a given flavor, we then find that any gauge-parameter dependence of quark self-energies on the ''mass shell'' is eliminated provided that the mass shell is made to coincide with both the expansion-parameter mass occurring in the operator-product expansion of and the standard electroweak mass acquired via the Yukawa coupling to the usual scalar vacuum expectation value of spontaneous symmetry breaking. This result indicates that if the QCD-generated order parameter and associated dynamical mass(es) m/sub q//sup dyn/ are utilized as external input parameters in electroweak calculations involving hadrons, then new corrections must be introduced into the q-barqW and q-barqZ vertices in order to preserve SU(2) x U(1) Ward identities

  13. Automatic calculation of massive two-loop self-energies with XLOOPS

    International Nuclear Information System (INIS)

    Franzkowski, J.

    1997-01-01

    Within the program package XLOOPS it is possible to calculate self-energies up to the two-loop level for arbitrary massive particles. The program package -written in MAPLE (Char et al., Maple V Language Reference Manual (Springer, 1991); Char et al., Maple V Library Reference Manual (Springer, 1991)) - is designed to deal with the full tensor structure of the occurring integrals. This means that applications are not restricted to those cases where the reduction to scalars via equivalence theorem is allowed. The algorithms handle two-loop integrals analytically if this is possible. For those topologies where no analytic result for the general mass case is available, the diagrams are reduced to integral representations which encounter at most at two-fold integration. These integral representations are numerically stable and can be performed easily using VEGAS (Lepage, J. Comp. Phys. 27 (1978) 192; Lepage, Cornell Univ. Preprint CLNS-80/447 (1980)). (orig.)

  14. Self-energy correction to the hyperfine splitting for excited states

    International Nuclear Information System (INIS)

    Wundt, B. J.; Jentschura, U. D.

    2011-01-01

    The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Zα, where Z is the nuclear-charge number and α is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13≤n≤16, and orbital angular momenta l=n-2 and l=n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with l≥2 and arbitrary n, l, and total angular momentum j. The low-energy contributions are written in the form of generalized Bethe logarithms and evaluated for selected states.

  15. Filling- and interaction-driven Mott transition. Quantum cluster calculations within self-energy-functional theory

    International Nuclear Information System (INIS)

    Balzer, Matthias

    2008-01-01

    The central goal of this thesis is the examination of strongly correlated electron systems on the basis of the two-dimensional Hubbard model. We analyze how the properties of the Mott insulator change upon doping and with interaction strength. The numerical evaluation is done using quantum cluster approximations, which allow for a thermodynamically consistent description of the ground state properties. The framework of self-energy-functional theory offers great flexibility for the construction of cluster approximations. A detailed analysis sheds light on the quality and the convergence properties of different cluster approximations within the self-energy-functional theory. We use the one-dimensional Hubbard model for these examinations and compare our results with the exact solution. In two dimensions the ground state of the particle-hole symmetric model at half-filling is an antiferromagnetic insulator, independent of the interaction strength. The inclusion of short-range spatial correlations by our cluster approach leads to a considerable improvement of the antiferromagnetic order parameter as compared to dynamical mean-field theory. In the paramagnetic phase we furthermore observe a metal-insulator transition as a function of the interaction strength, which qualitatively differs from the pure mean-field scenario. Starting from the antiferromagnetic Mott insulator a filling-controlled metal-insulator transition in a paramagnetic metallic phase can be observed. Depending on the cluster approximation used an antiferromagnetic metallic phase may occur at first. In addition to long-range antiferromagnetic order, we also considered superconductivity in our calculations. The superconducting order parameter as a function of doping is in good agreement with other numerical methods, as well as with experimental results. (orig.)

  16. All orders transport theory from the multiple scattering expansion of the self-energy. The central cuts

    International Nuclear Information System (INIS)

    Gagnon, J.S.; Fillion-Gourdeau, F.; Sangyong Jeong; RIKEN Research Center, Upton, NY

    2006-01-01

    We use the full multiple scattering expansion of the retarded self-energy to obtain the gain and loss rates present in the Kadanoff-Baym relativistic transport equation. The rates we obtain include processes with any number of particles. As a first approximation, we only consider central cuts in the self-energies, but otherwise our results are general. We specialize to the case of scalar field theory to compare with lowest order results. The main application of this work is relativistic transport theory of very dense systems, such as the quark-gluon plasma or the early universe, where multi-particle interactions are important. (author)

  17. Accurate Quasiparticle Spectra from the T-Matrix Self-Energy and the Particle-Particle Random Phase Approximation.

    Science.gov (United States)

    Zhang, Du; Su, Neil Qiang; Yang, Weitao

    2017-07-20

    The GW self-energy, especially G 0 W 0 based on the particle-hole random phase approximation (phRPA), is widely used to study quasiparticle (QP) energies. Motivated by the desirable features of the particle-particle (pp) RPA compared to the conventional phRPA, we explore the pp counterpart of GW, that is, the T-matrix self-energy, formulated with the eigenvectors and eigenvalues of the ppRPA matrix. We demonstrate the accuracy of the T-matrix method for molecular QP energies, highlighting the importance of the pp channel for calculating QP spectra.

  18. Lowest-order corrections to the RPA polarizability and GW self-energy of a semiconducting wire

    NARCIS (Netherlands)

    Groot, de H.J.; Ummels, R.T.M.; Bobbert, P.A.; van Haeringen, W.

    1996-01-01

    We present the results of the addition of lowest-order vertex and self-consistency corrections to the RPA polarizability and the GW self-energy for a semiconducting wire. It is found that, when starting from a local density approximation zeroth-order Green function and systematically including these

  19. Induced self-energy on a static scalar charged particle in the spacetime of a global monopole with finite core

    International Nuclear Information System (INIS)

    Barbosa, D; De Freitas, U; De Mello, E R Bezerra

    2011-01-01

    We analyze the induced self-energy and self-force on a scalar point-like charged test particle placed at rest in the spacetime of a global monopole admitting a general spherically symmetric inner structure to it. In order to develop this analysis we calculate the three-dimensional Green's function associated with this physical system. We explicitly show that for points outside the monopole's core the scalar self-energy presents two distinct contributions. The first one is induced by the non-trivial topology of the global monopole considered as a point-like defect and the second is a correction induced by the non-vanishing inner structure attributed to it. For points inside the monopole, the self-energy also present a similar structure, where now the first contribution depends on the geometry of the spacetime inside. As illustrations of the general procedure adopted, two specific models, namely flower-pot and the ballpoint-pen, are considered for the region inside. For these two different situations, we were able to obtain exact expressions for the self-energies and self-forces in the regions outside and inside the global monopole.

  20. Induced self-energy on a static scalar charged particle in the spacetime of a global monopole with finite core

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, D; De Freitas, U; De Mello, E R Bezerra, E-mail: denis.barros@ifpb.edu.br, E-mail: umbelino@fisica.ufpb.br, E-mail: emello@fisica.ufpb.br [Instituto Federal de Educacao, Ciencia e Tecnologia da ParaIba, 58.800-970, Sousa, PB (Brazil)

    2011-03-21

    We analyze the induced self-energy and self-force on a scalar point-like charged test particle placed at rest in the spacetime of a global monopole admitting a general spherically symmetric inner structure to it. In order to develop this analysis we calculate the three-dimensional Green's function associated with this physical system. We explicitly show that for points outside the monopole's core the scalar self-energy presents two distinct contributions. The first one is induced by the non-trivial topology of the global monopole considered as a point-like defect and the second is a correction induced by the non-vanishing inner structure attributed to it. For points inside the monopole, the self-energy also present a similar structure, where now the first contribution depends on the geometry of the spacetime inside. As illustrations of the general procedure adopted, two specific models, namely flower-pot and the ballpoint-pen, are considered for the region inside. For these two different situations, we were able to obtain exact expressions for the self-energies and self-forces in the regions outside and inside the global monopole.

  1. Bifurcation of the Quark Self-Energy: Infra-Red and Ultra-Violet Cut-Offs

    NARCIS (Netherlands)

    Atkinson, D.; Johnson, P. W.

    1987-01-01

    The quark self-energy in massless QCD is studied in the approximation that both the quark-gluon vertex and the gluon propagator remain bare. It is shown that chiral invariance is not spontaneously broken at a critical coupling λc>0, unless both infrared and ultraviolet cutoffs are introduced.

  2. On the s → d self-energy transition ∝ αsGF and the relevance for the ΔI = 1/2 and ε'/ε puzzles

    International Nuclear Information System (INIS)

    Eeg, J.O.

    1987-01-01

    I have considered the s → d self-energy transition diagrams ∝ α s G F - or ''self-penguins'' - recently proposed by Shabalin as the explanation of the ΔI=1/2 rule for K → ππ decays. The effect of such a self-energy transition on physical amplitudes is considered in terms of a chiral quark loop model for K → π. A self-penguin contribution proportional to the dot product of the pion and kaon four-momenta is found. However, this contribution can at most account for 5% of the observed ΔI = 1/2 amplitude. The self-penguin contribution to the CP-violating quantity ε'/ε calculated within the same framework could be as large as half of the standard penguin contribution. (orig.)

  3. On the s→d self energy transition ∼αs GF and the relevance for the ΔI=1/2 and ε'/ε puzzles

    International Nuclear Information System (INIS)

    Eeg, J.O.

    1987-05-01

    The s→d self energy transitions diagrams ∼α s G F or s elf-penguins , recently proposed by Shabalin as the explanation of the ΔI=1/2 rule for K→ππ decays, have been considered. The effect of such self-energy transition on physical amplitudes is considered in terms of a chiral quark loop model for K→π. A self-penguin contribution proportional to the dot product of the pion and kaon four momenta is found. However, this contribution can at most account for 5% of the observed ΔI=1/2 amplitude. The self-penguin contribution to the CP-violating quantity ε'/ε calculated within the same framework could be as big as half of the standard penguin contribution

  4. CdSe/CdTe interface band gaps and band offsets calculated using spin-orbit and self-energy corrections

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M. [Centro de Pesquisas Avancadas Wernher von Braun, Av. Alice de Castro P.N. Mattosinho 301, CEP 13098-392 Campinas, SP (Brazil); Ferreira, L.G. [Departamento de Fisica dos Materiais e Mecanica, Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil); Fonseca, L.R.C. [Center for Semiconductor Components, State University of Campinas, R. Pandia Calogeras 90, 13083-870 Campinas, SP (Brazil); Ramprasad, R. [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 North Eagleville Road, Storrs, CT 06269 (United States)

    2012-09-20

    We performed ab initio calculations of the electronic structures of bulk CdSe and CdTe, and their interface band alignments on the CdSe in-plane lattice parameters. For this, we employed the LDA-1/2 self-energy correction scheme to obtain corrected band gaps and band offsets. Our calculations include the spin-orbit effects for the bulk cases, which have shown to be of importance for the equilibrium systems and are possibly degraded in these strained semiconductors. Therefore, the SO showed reduced importance for the band alignment of this particular system. Moreover, the electronic structure calculated along the transition region across the CdSe/CdTe interface shows an interesting non-monotonic variation of the band gap in the range 0.8-1.8 eV, which may enhance the absorption of light for corresponding frequencies at the interface between these two materials in photovoltaic applications.

  5. Superconductivity induced by flexural modes in non-σh-symmetric Dirac-like two-dimensional materials: A theoretical study for silicene and germanene

    Science.gov (United States)

    Fischetti, Massimo V.; Polley, Arup

    2018-04-01

    In two-dimensional crystals that lack symmetry under reflections on the horizontal plane of the lattice (non-σh-symmetric), electrons can couple to flexural modes (ZA phonons) at first order. We show that in materials of this type that also exhibit a Dirac-like electron dispersion, the strong coupling can result in electron pairing mediated by these phonons, as long as the flexural modes are not damped or suppressed by additional interactions with a supporting substrate or gate insulator. We consider several models: The weak-coupling limit, which is applicable only in the case of gapped and parabolic materials, like stanene and HfSe2, thanks to the weak coupling; the full gap-equation, solved using the constant-gap approximation and considering statically screened interactions; its extensions to energy-dependent gap and to dynamic screening. We argue that in the case of silicene and germanene superconductivity mediated by this process can exhibit a critical temperature of a few degrees K, or even a few tens of degrees K when accounting for the effect of a high-dielectric-constant environment. We conclude that the electron/flexural-modes coupling should be included in studies of possible superconductivity in non-σh-symmetric two-dimensional crystals, even if alternative forms of coupling are considered.

  6. Superconductivity induced by interfacial coupling to magnons

    Science.gov (United States)

    Rohling, Niklas; Fjærbu, Eirik Løhaugen; Brataas, Arne

    2018-03-01

    We consider a thin normal metal sandwiched between two ferromagnetic insulators. At the interfaces, the exchange coupling causes electrons within the metal to interact with magnons in the insulators. This electron-magnon interaction induces electron-electron interactions, which in turn can result in p -wave superconductivity. We solve the gap equation numerically and estimate the critical temperature. In yttrium iron garnet (YIG)-Au-YIG trilayers, superconductivity sets in at temperatures somewhere in the interval between 1 and 10 K. EuO-Au-EuO trilayers require a lower temperature, in the range from 0.01 to 1 K.

  7. Strong Plasmon-Phonon Splitting and Hybridization in 2D Materials Revealed through a Self-Energy Approach

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Saavedra, J. R. M.; Thygesen, Kristian Sommer

    2017-01-01

    splitting due to this coupling, resulting in a characteristic avoided crossing scheme. We base our results on a computationally efficient approach consisting in including many-body interactions through the electron self-energy. We specify this formalism for a description of plasmons based upon a tight...... nanotriangles with varied size, where we predict remarkable peak splittings and other radical modifications in the spectra due to plasmon interactions with intrinsic optical phonons. Our method is equally applicable to other 2D materials and provides a simple approach for investigating coupling of plasmons...

  8. Nonequilibrium self-energy functional theory. Accessing the real-time dynamics of strongly correlated fermionic lattice systems

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Felix

    2016-07-05

    The self-energy functional theory (SFT) is extended to the nonequilibrium case and applied to the real-time dynamics of strongly correlated lattice-fermions. Exploiting the basic structure of the well established equilibrium theory the entire formalism is reformulated in the language of Keldysh-Matsubara Green's functions. To this end, a functional of general nonequilibrium self-energies is constructed which is stationary at the physical point where it moreover yields the physical grand potential of the initial thermal state. Nonperturbative approximations to the full self-energy can be constructed by reducing the original lattice problem to smaller reference systems and varying the functional on the space of the respective trial self-energies, which are parametrized by the reference system's one-particle parameters. Approximations constructed in this way can be shown to respect the macroscopic conservation laws related to the underlying symmetries of the original lattice model. Assuming thermal equilibrium, the original SFT is recovered from the extended formalism. However, in the general case, the nonequilibrium variational principle comprises functional derivatives off the physical parameter space. These can be carried out analytically to derive inherently causal conditional equations for the optimal physical parameters of the reference system and a computationally realizable propagation scheme is set up. As a benchmark for the numerical implementation the variational cluster approach is applied to the dynamics of a dimerized Hubbard model after fast ramps of its hopping parameters. Finally, the time-evolution of a homogeneous Hubbard model after sudden quenches and ramps of the interaction parameter is studied by means of a dynamical impurity approximation with a single bath site. Sharply separated by a critical interaction at which fast relaxation to a thermal final state is observed, two differing response regimes can be distinguished, where the

  9. Two-loop self-energy in the Lamb shift of the ground and excited states of hydrogenlike ions

    Science.gov (United States)

    Yerokhin, V. A.

    2018-05-01

    The two-loop self-energy correction to the Lamb shift of hydrogenlike ions is calculated for the 1 s , 2 s , and 2 p1 /2 states and nuclear charge numbers Z =30 -100 . The calculation is performed to all orders in the nuclear binding strength parameter Z α . As compared to previous calculations of this correction, numerical accuracy is improved by an order of magnitude and the region of the nuclear charges is extended. An analysis of the Z dependence of the obtained results demonstrates their consistency with the known Z α -expansion coefficients.

  10. Singularity-free electrodynamics for point charges and dipoles: a classical model for electron self-energy and spin

    International Nuclear Information System (INIS)

    Blinder, S M

    2003-01-01

    It is shown how point charges and point dipoles with finite self-energies can be accommodated in classical electrodynamics. The key idea is the introduction of constitutive relations for the electromagnetic vacuum, which actually mirrors the physical reality of vacuum polarization. Our results reduce to conventional electrodynamics for scales large compared to the classical electron radius r 0 ∼ 2.8 x 10 -15 m. A classical simulation for a structureless electron is proposed, with the appropriate values of mass, spin and magnetic moment

  11. Analytic two-loop results for self-energy- and vertex-type diagrams with one non-zero mass

    International Nuclear Information System (INIS)

    Fleischer, J.; Kotikov, A.V.; Veretin, O.L.

    1999-01-01

    For a large class of two-loop self-energy- and vertex-type diagrams with only one non-zero mass (m) and the vertices also with only one non-zero external momentum squared (q 2 ) the first few expansion coefficients are calculated by the large mass expansion. This allows us to 'guess' the general structure of these coefficients and to verify them in terms of certain classes of 'basis elements', which are essentially harmonic sums. Since for this case with only one non-zero mass the large mass expansion and the Taylor series in terms of q 2 are identical, this approach yields analytic expressions of the Taylor coefficients, from which the diagram can be easily evaluated numerically in a large domain of the complex q 2 -plane by well known methods. It is also possible to sum the Taylor series and present the results in terms of polylogarithms

  12. Reparameterization invariance of NRQED self-energy corrections and improved theory for excited D states in hydrogenlike systems

    International Nuclear Information System (INIS)

    Wundt, Benedikt J.; Jentschura, Ulrich D.

    2008-01-01

    Canonically, the quantum electrodynamic radiative corrections in bound systems have been evaluated in photon energy regularization, i.e., using a noncovariant overlapping parameter that separates the high-energy relativistic scales of the virtual quanta from the nonrelativistic domain. Here, we calculate the higher-order corrections to the one-photon self-energy calculation with three different overlapping parameters (photon energy, photon mass and dimensional regularization) and demonstrate the reparameterization invariance of nonrelativistic quantum electrodynamics (NRQED) using this particular example. We also present new techniques for the calculation of the low-energy part of this correction, which lead to results for the Lamb shift of highly excited states that are important for high-precision spectroscopy

  13. Reparameterization invariance of NRQED self-energy corrections and improved theory for excited D states in hydrogenlike systems

    Energy Technology Data Exchange (ETDEWEB)

    Wundt, Benedikt J. [Max-Planck-Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany); Jentschura, Ulrich D. [Max-Planck-Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg (Germany); Institut fuer Theoretische Physik, Philosophenweg 16, 69120 Heidelberg (Germany)], E-mail: ulrich.jentschura@mpi-hd.mpg.de

    2008-01-24

    Canonically, the quantum electrodynamic radiative corrections in bound systems have been evaluated in photon energy regularization, i.e., using a noncovariant overlapping parameter that separates the high-energy relativistic scales of the virtual quanta from the nonrelativistic domain. Here, we calculate the higher-order corrections to the one-photon self-energy calculation with three different overlapping parameters (photon energy, photon mass and dimensional regularization) and demonstrate the reparameterization invariance of nonrelativistic quantum electrodynamics (NRQED) using this particular example. We also present new techniques for the calculation of the low-energy part of this correction, which lead to results for the Lamb shift of highly excited states that are important for high-precision spectroscopy.

  14. Similarity of the leading contributions to the self-energy and the thermodynamics in two- and three-dimensional Fermi Liquids

    International Nuclear Information System (INIS)

    Coffey, D.; Bedell, K.S.

    1993-01-01

    We compare the self-energy and entropy of a two- and three-dimensional Fermi Liquids (FLs) using a model with a contact interaction between fermions. For a two-dimensional (2D) FL we find that there are T 2 contributions to the entropy from interactions separate from those due to the collective modes. These T 2 contributions arise from nonanalytic corrections to the real part of the self-energy and areanalogous to T 3 lnT contributions present in the entropy of a three-dimensional (3D) FL. The difference between the 2D and 3D results arises solely from the different phase space factors

  15. Analysis of the 48Ca neutron skin using a nonlocal dispersive-optical-model self-energy

    Science.gov (United States)

    Atkinson, Mack; Mahzoon, Hossein; Dickhoff, Willem; Charity, Robert

    2017-09-01

    A nonlocal dispersive-optical-model (DOM) analysis of the 40Ca and 48Ca nuclei has been implemented. The real and imaginary potentials are constrained by fitting to elastic-scattering data, total and reaction cross sections, energy level information, particle number, and the charge densities of 40Ca and 48Ca, respectively. The nonlocality of these potentials permits a proper dispersive self-energy which accurately describes both positive and negative energy observables. 48Ca is of particular interest because it is doubly magic and has a neutron skin due to the excess of neutrons. The DOM neutron skin radius is found to be rskin = 0.245 , which is larger than most previous calculations. The neutron skin is closely related to the symmetry energy which is a crucial part of the nuclear equation of state. The combined analysis of 40Ca and 48Ca energy densities provides a description of the density dependence of the symmetry energy which is compared with the 48Ca neutron skin. Results for 208Pb will also become available in the near future. NSF.

  16. Theoretical study of charge trapping levels in silicon nitride using the LDA-1/2 self-energy correction scheme for excited states

    International Nuclear Information System (INIS)

    Patrocinio, Weslley S.; Ribeiro, Mauro; Fonseca, Leonardo R.C.

    2012-01-01

    Silicon nitride, with a permittivity mid-way between SiO 2 and common high-k materials such as HfO 2 , is widely used in microelectronics as an insulating layer on top of oxides where it serves as an impurity barrier with the positive side effect of increasing the dielectric constant of the insulator when it is SiO 2 . It is also employed as charge storage in nonvolatile memory devices thanks to its high concentration of charge traps. However, in the case of memories, it is still unclear which defects are responsible for charge trapping and what is the impact of defect concentration on the structural and electronic properties of SiN x . Indeed, for the amorphous phase the band gap was measured in the range 5.1–5.5 eV, with long tails in the density of states penetrating the gap region. It is still not clear which defects are responsible for the tails. On the other hand, the K-center defects have been associated with charge trapping, though its origin is assigned to one Si back bond. To investigate the contribution of defect states to the band edge tails and band gap states, we adopted the β phase of stoichiometric silicon nitride (β-Si 3 N 4 ) as our model material and calculated its electronic properties employing ab initio DFT/LDA simulations with self-energy correction to improve the location of defect states in the SiN x band gap through the correction of the band gap underestimation typical of DFT/LDA. We considered some important defects in SiN x , as the Si anti-site and the N vacancy with H saturation, in two defect concentrations. The location of our calculated defect levels in the band gap correlates well with the available experimental data, offering a structural explanation to the measured band edge tails and charge trapping characteristics.

  17. H+H- interaction up to higher orders of perturbation theory in the model with two Higgs doublets (self-energy and vertex diagrams)

    International Nuclear Information System (INIS)

    Dvoeglazov, V.V.; Skachkov, N.B.

    1991-01-01

    Self-energy and vertex blocks that enter into the amplitude of Higgs-Higgs-interaction are calculated up to the fourth order of perturbation theory in the framework of the model of electroweak interaction with two Higgs doublets and an arbitrary number of fermions. The renormalization is performed on the mass shell of the physical fields after a spontaneous symmetry breaking. The values of the coupling constants are, as a rule, not concretized in the paper. In the cases where it is needed to use them, their values obtained in the model with the minimal supersymmetric extension of the standard model (MSSM) are taken. 29 refs.; 1 tab

  18. Self-energy of the Δ-isobar in nuclear matter for the Paris and the Green-Niskanen-Sainio potentials

    International Nuclear Information System (INIS)

    Dey, J.; Abdul Matin, M.; Samanta, B.C.

    1985-11-01

    A coupled channel calculation, with the compensated Paris potential and the isobar transition potential due to Green, Niskanen and Sainio, yields the nucleon and isobar self-energies in nuclear matter. Unlike the Reid soft core, the Paris potential is found to bind the isobar at small momentum by a potential of the order of 10 MeV. The change in the binding energy and the wound integral in nuclear matter, due to the explicit treatment of isobar degrees of freedom, is small. (author)

  19. QED based on self-energy: The relativistic 2S1/2 → 1S1/2+1γ decay rates of hydrogenlike atoms

    International Nuclear Information System (INIS)

    Barut, A.O.; Salamin, Y.I.

    1989-07-01

    Within the framework of the recently advanced formulation of QED based on self-energy, we calculate the relativistic rates of the 2S 1/2 → 1S 1/2 +1γ transition in the hydrogen isoelectronic sequence for values of Z ranging between 1 and 92. We compare our results with those of Johnson (Phys. Rev. Lett. 29, 1123 (1972)) and Parpia and Johnson (Phys. Rev. A 26, 1142 (1982)) and find them to be in good agreement with both. (author). 12 refs, 1 tab

  20. QED based on self-energy: The relativistic 2S1/2→1S1/2+1γ decay rates of hydrogenlike atoms

    International Nuclear Information System (INIS)

    Barut, A.O.; Salamin, Y.I.

    1991-01-01

    Within the framework of the recently advanced formulation of QED based on self-energy, we calculate the relativistic rates of the 2S 1/2 →1S 1/2 +1γ transition in the hydrogen isoelectronic sequence for values of Z ranging between 1 and 92. We compare our results with those of Johnson [Phys. Rev. Lett. 29, 1123 (1972)] and Parpia and Johnson [Phys. Rev. A 26, 1142 (1982)], analytically and numerically. Although the two approaches are quite different, the formulas for decay rates are shown to be equivalent

  1. Quantum electrodynamics based on self-energy, without second quantization: The Lamb shift and long-range Casimir-Polder van der Waals forces near boundaries

    International Nuclear Information System (INIS)

    Barut, A.O.; Dowling, J.P.

    1986-12-01

    Using a previously formulated theory of quantum electrodynamics based on self-energy, we give a general method for computing the Lamb shift and related Casimir-Polder energies for a quantum system in the vicinity of perfectly conducting boundaries. Our results are exact and easily extendable to a full covariant relativistic form. As a particular example we apply the method to an atom near an infinite conducting plane, and we recover the standard QED results (which are known only in the dipole approximation) in a simple and straightforward manner. This is accomplished in the context of the new theory which is not second quantized and contains no vacuum fluctuations. (author)

  2. Self-energies of octet and decuplet baryons due to the coupling to the baryon-meson continuum

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Tecocoatzi, H. [INFN, Sezione di Genova, Genova (Italy); Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, Mexico (Mexico); Bijker, R. [Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, Mexico (Mexico); Ferretti, J. [Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China); Dipartimento di Fisica, Universita di Roma Sapienza, Roma (Italy); INFN, Roma (Italy); Santopinto, E. [INFN, Sezione di Genova, Genova (Italy)

    2017-06-15

    We present an unquenched quark model calculation of the mass shifts of ground-state octet and decuplet baryons due to the coupling to the meson-baryon continuum. All ground-state baryons and pseudoscalar mesons are included in our calculation as intermediate states. The q anti q pair creation effects are taken explicitly into account through a microscopic, QCD-inspired, quark-antiquark pair creation mechanism. (orig.)

  3. A quantum theory of the self-energy of non-relativistic fermions and of the Coulomb-Yukawa force acting between them

    International Nuclear Information System (INIS)

    Ernst, V.

    1978-01-01

    The idea of the systematic Weisskopf-Wigner approximation as used sporadically in atomic physics and quantum optics, is extended here to the interaction of a field of non-relativistic fermions with a field of relativistic bosons. It is shown that the usual (non-existing) interaction Hamiltonian of this system can be written as a sum of a countable number of self-adjoint and bounded partial Hamiltonians. The system of these Hamiltonians defines the order hierarchy of the present approximation scheme. To demonstrate its physical utility it is shown that in a certain order it provides satisfactory quantum theory of the 'self-energy' of the fermions under discussion. This is defined as the binding energy of bosons bound to the fermions and building up the latter's 'individual Coulomb or Yukawa fields' in the sense of expectation values of the corresponding field operator. In states of more than one fermion the bound photons act as a mediating agent between the fermions; this mechanism closely resembles the Coulomb or Yukawa 'forces' used in conventional non-relativistic quantum mechanics. (author)

  4. Semi-analytic approach to higher-order corrections in simple muonic bound systems: vacuum polarization, self-energy and radiative-recoil

    Energy Technology Data Exchange (ETDEWEB)

    Jentschura, U.D. [Department of Physics, Missouri University of Science and Technology, Rolla MO65409 (United States); Institut fur Theoretische Physik, Universitat Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Wundt, B.J. [Department of Physics, Missouri University of Science and Technology, Rolla MO65409 (United States)

    2011-12-15

    The current discrepancy of theory and experiment observed recently in muonic hydrogen necessitates a reinvestigation of all corrections to contribute to the Lamb shift in muonic hydrogen ({mu}H), muonic deuterium ({mu}D), the muonic {sup 3}He ion (denoted here as {mu}{sup 3}He{sup +}), as well as in the muonic {sup 4}He ion ({mu}{sup 4}He{sup +}). Here, we choose a semi-analytic approach and evaluate a number of higher-order corrections to vacuum polarization (VP) semi-analytically, while remaining integrals over the spectral density of VP are performed numerically. We obtain semi-analytic results for the second-order correction, and for the relativistic correction to VP. The self-energy correction to VP is calculated, including the perturbations of the Bethe logarithms by vacuum polarization. Sub-leading logarithmic terms in the radiative-recoil correction to the 2S-2P Lamb shift of order {alpha}(Z{alpha}){sup 5{mu}3}ln(Z{alpha})/(m{sub {mu}mN}) where {alpha} is the fine structure constant, are also obtained. All calculations are nonperturbative in the mass ratio of orbiting particle and nucleus. (authors)

  5. Semi-analytic approach to higher-order corrections in simple muonic bound systems: vacuum polarization, self-energy and radiative-recoil

    International Nuclear Information System (INIS)

    Jentschura, U.D.; Wundt, B.J.

    2011-01-01

    The current discrepancy of theory and experiment observed recently in muonic hydrogen necessitates a reinvestigation of all corrections to contribute to the Lamb shift in muonic hydrogen (μH), muonic deuterium (μD), the muonic 3 He ion (denoted here as μ 3 He + ), as well as in the muonic 4 He ion (μ 4 He + ). Here, we choose a semi-analytic approach and evaluate a number of higher-order corrections to vacuum polarization (VP) semi-analytically, while remaining integrals over the spectral density of VP are performed numerically. We obtain semi-analytic results for the second-order correction, and for the relativistic correction to VP. The self-energy correction to VP is calculated, including the perturbations of the Bethe logarithms by vacuum polarization. Sub-leading logarithmic terms in the radiative-recoil correction to the 2S-2P Lamb shift of order α(Zα) 5 μ 3 ln(Zα)/(m μ m N ) where α is the fine structure constant, are also obtained. All calculations are nonperturbative in the mass ratio of orbiting particle and nucleus. (authors)

  6. Two-Loop Quark Self-Energy in a New Formalism; 2, Renormalization of the Quark Propagator in the Light-Cone Gauge

    CERN Document Server

    Leibbrandt, George; Leibbrandt, George; Williams, Jimmy D.

    2000-01-01

    The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the noncovariant light-cone gauge (lcg). (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n^*-prescription for the spurious poles of 1/qn, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma_2 contains both covariant and noncovariant components, and is a local function of the external momentum p, even off the mass-shell, as all nonlocal divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma_2 implies a quark mass counterterm of the form $\\delta m (lcg) = m\\tilde\\alpha_s C_F(3+\\tilde\\alpha_sW) + {\\rm O} (\\tilde\\alpha_s^3)$, the dimensional regulator epsilon, and on th...

  7. Two-loop quark self-energy in a new formalism; 2, Renormalization of the quark propagator in the light-cone gauge

    CERN Document Server

    Leibbrandt, G

    2000-01-01

    For pt.I see ibid., vol.440, p.537-602, 1995. The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the non-covariant light-cone gauge (LCG), n.A/sup a/(x)=0, n/sup 2/=0. (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n*/sub mu /-prescription for the spurious poles of (q.n)/sup -1/, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma /sub 2/ contains both covariant and non-covariant components, and is a local function of the external momentum p, even off the mass-shell, as all non-local divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma /sub 2/ implies a quark mass counterterm of the form delta m(LCG)=m alpha /sub...

  8. Inhomogeneous spectral moment sum rules for the retarded Green function and self-energy of strongly correlated electrons or ultracold fermionic atoms in optical lattices

    International Nuclear Information System (INIS)

    Freericks, J. K.; Turkowski, V.

    2009-01-01

    Spectral moment sum rules are presented for the inhomogeneous many-body problem described by the fermionic Falicov-Kimball or Hubbard models. These local sum rules allow for arbitrary hoppings, site energies, and interactions. They can be employed to quantify the accuracy of numerical solutions to the inhomogeneous many-body problem such as strongly correlated multilayered devices, ultracold atoms in an optical lattice with a trap potential, strongly correlated systems that are disordered, or systems with nontrivial spatial ordering such as a charge-density wave or a spin-density wave. We also show how the spectral moment sum rules determine the asymptotic behavior of the Green function, self-energy, and dynamical mean field when applied to the dynamical mean-field theory solution of the many-body problem. In particular, we illustrate in detail how one can dramatically reduce the number of Matsubara frequencies needed to solve the Falicov-Kimball model while still retaining high precision, and we sketch how one can incorporate these results into Hirsch-Fye quantum Monte Carlo solvers for the Hubbard (or more complicated) models. Since the solution of inhomogeneous problems is significantly more time consuming than periodic systems, efficient use of these sum rules can provide a dramatic speed up in the computational time required to solve the many-body problem. We also discuss how these sum rules behave in nonequilibrium situations as well, where the Hamiltonian has explicit time dependence due to a driving field or due to the time-dependent change in a parameter such as the interaction strength or the origin of the trap potential.

  9. Filling- and interaction-driven Mott transition. Quantum cluster calculations within self-energy-functional theory; Fuellungs- und wechselwirkungsabhaengiger Mott-Uebergang. Quanten-Cluster-Rechnungen im Rahmen der Selbstenergiefunktional-Theorie

    Energy Technology Data Exchange (ETDEWEB)

    Balzer, Matthias

    2008-07-01

    The central goal of this thesis is the examination of strongly correlated electron systems on the basis of the two-dimensional Hubbard model. We analyze how the properties of the Mott insulator change upon doping and with interaction strength. The numerical evaluation is done using quantum cluster approximations, which allow for a thermodynamically consistent description of the ground state properties. The framework of self-energy-functional theory offers great flexibility for the construction of cluster approximations. A detailed analysis sheds light on the quality and the convergence properties of different cluster approximations within the self-energy-functional theory. We use the one-dimensional Hubbard model for these examinations and compare our results with the exact solution. In two dimensions the ground state of the particle-hole symmetric model at half-filling is an antiferromagnetic insulator, independent of the interaction strength. The inclusion of short-range spatial correlations by our cluster approach leads to a considerable improvement of the antiferromagnetic order parameter as compared to dynamical mean-field theory. In the paramagnetic phase we furthermore observe a metal-insulator transition as a function of the interaction strength, which qualitatively differs from the pure mean-field scenario. Starting from the antiferromagnetic Mott insulator a filling-controlled metal-insulator transition in a paramagnetic metallic phase can be observed. Depending on the cluster approximation used an antiferromagnetic metallic phase may occur at first. In addition to long-range antiferromagnetic order, we also considered superconductivity in our calculations. The superconducting order parameter as a function of doping is in good agreement with other numerical methods, as well as with experimental results. (orig.)

  10. Electric- and magnetic-dipole contributions to a theory of radiation reaction field and atom self-energy: An operator reaction field

    International Nuclear Information System (INIS)

    Obada, A.S.F.; Mahran, M.H.

    1982-08-01

    The consequences of including magnetic-dipole contributions, besides the electric-dipole, are considered in the operators for the radiation field. The Bloch equations which describe the two-level atom operators are modified. These equations together with the field operators are discussed, and the contributions are manifested. The spectrum for spontaneous emission and a generalized dynamical Stark effect are obtained. Rabi frequency is modified. (author)

  11. Disorder effects in the t-J model

    International Nuclear Information System (INIS)

    Caprara, S.; De Palo, S.; Castellani, C.; Di Castro, C.; Grilli, M.

    1995-01-01

    We investigate the effects of disorder in the single-band t-J model, mainly devoting our analysis to the superconducting phases with d-wave or s-wave symmetry. We present evidence that, in the presence of strong correlation with reduced bandwidth and Van Hove singularity in the density of states, a self-consistent approach for the self-energy associated to the impurities is required. Numerical estimates of the reduction of the critical temperature with disorder are given. When a constant imaginary part of the self-energy is taken, avoiding self-consistency, the reduction of the critical temperature is overestimated

  12. Self-energy production applied to buildings

    Energy Technology Data Exchange (ETDEWEB)

    Carlo, Fabricio Ramos del; Balestieri, Jose Antonio Perrella [Sao Paulo State University Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil)], E-mail: perrella@feg.unesp.br; Holanda, Marcelo Rodrigues de [Sao Paulo Univ. (EEL/USP), Lorena, SP (Brazil). Engineering School], E-mail: marcelo@debas.eel.usp.br

    2010-07-01

    The decentralization of energy production in order to obtain better environmental conditions, reducing greenhouse gas emissions and the cost reduction of electricity and thermal energy consumed in residential buildings has been proposed in the literature. This paper proposes to demonstrate what are the chances of having a microcogeneration system toward the residential application. In this study, we contemplate the technologies involved and their possible inputs that are arranged in a superstructure to be studied. As a first step we obtain the cost of the products generated by the configuration that consists basically of two sources of power generation, and through optimization calculations intended to obtain the best configuration, taking into consideration the selection between four fuels, two equipment generators (Fuel Cell and Internal Combustion Engine)and three levels of energy production for each one. An economic analysis is also presented to evaluate the opportunity of selling the energy generated considering the fluctuations of the residential building consumption needs. (author)

  13. Self energy QED: Multipole spontaneous emission

    International Nuclear Information System (INIS)

    Salamin, Y.I.

    1990-08-01

    Within the context of Barut's self-field approach, we write the exact expression of the spontaneous atomic decay rate (Phys. Rev. A37, 2284 (1988)), in the long wavelength approximation, in terms of electric- and magnetic-like multipole contributions which are related to the matrix elements of the transition charge and current distributions of the relativistic electron. A number of features of these expressions are discussed and their generalization to interacting composite systems is also pointed out. (author). 8 refs

  14. Self-energy quantum electrodynamics: Multipole radiation

    International Nuclear Information System (INIS)

    Salamin, Y.I.

    1993-01-01

    Within the context of Barut's self-field approach to quantum electrodynamics, it is shown that the exact relativistic expression for the Einstein A-coefficient of atomic spontaneous emission reduces, in the long wavelength approximation, to a form containing electric- and magnetic-like multipole contributions related to the transition charge and current distributions of the relativistic electron. A number of interesting features of the expressions involved are discussed, and their generalization to interacting composite systems is also pointed out. 10 refs

  15. Selfenergy effect on the magnetic ordering transition in the mono- and bilayer honeycomb Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Honerkamp, Carsten [Institute for Theoretical Solid State Physics, RWTH Aachen University (Germany); JARA - Fundamentals of Future Information Technology, Aachen (Germany)

    2017-11-15

    We investigate the impact of electron self-energy corrections on potential antiferromagnetic ordering instabilities in mono- and bilayer graphene, modeled by a Hubbard-type lattice model with onsite interactions among the electrons, using a self-consistent random phase approximation (RPA). In qualitative agreement with earlier studies we find that the electronic interactions cause non-Fermi liquid behavior at low energies. In self-consistent RPA, the transition scales for antiferromagnetic ordering are renormalized significantly by these self-energy effects, both for interaction-driven and temperature-driven cases. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Superconductivity induced by oxygen doping in Y{sub 2}O{sub 2}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xiyue; Deng, Shuiquan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Gordon, Elijah E. [Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Whangbo, Myung-Hwan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Department of Chemistry, North Carolina State University, Raleigh, NC (United States)

    2017-08-14

    When doped with oxygen, the layered Y{sub 2}O{sub 2}Bi phase becomes a superconductor. This finding raises questions about the sites for doped oxygen, the mechanism of superconductivity, and practical guidelines for discovering new superconductors. We probed these questions in terms of first-principles calculations for undoped and O-doped Y{sub 2}O{sub 2}Bi. The preferred sites for doped O atoms are the centers of Bi{sub 4} squares in the Bi square net. Several Bi 6p x/y bands of Y{sub 2}O{sub 2}Bi are raised in energy by oxygen doping because the 2p x/y orbitals of the doped oxygen make antibonding possible with the 6p x/y orbitals of surrounding Bi atoms. Consequently, the condition necessary for the ''flat/steep'' band model for superconductivity is satisfied in O-doped Y{sub 2}O{sub 2}Bi. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. The effective matter potential for highly relativistic neutrinos

    International Nuclear Information System (INIS)

    Konstandin, Thomas; Ohlsson, Tommy

    2006-01-01

    We investigate matter effects on highly relativistic neutrinos. The self-energy of neutrinos is determined in an electron or neutrino background taking into account resonance and finite width effects of the gauge bosons. We find minor changes compared to the formerly used formula for the propagator function and large deviations of the effective width from the decay width of the gauge bosons considering higher moments of the electron or neutrino distribution function

  18. Probing ionization potential, electron affinity and self-energy effect on the spectral shape and exciton binding energy of quantum liquid water with self-consistent many-body perturbation theory and the Bethe–Salpeter equation

    Science.gov (United States)

    Ziaei, Vafa; Bredow, Thomas

    2018-05-01

    An accurate theoretical prediction of ionization potential (IP) and electron affinity (EA) is key in understanding complex photochemical processes in aqueous environments. There have been numerous efforts in literature to accurately predict IP and EA of liquid water, however with often conflicting results depending on the level of theory and the underlying water structures. In a recent study based on hybrid-non-self-consistent many-body perturbation theory (MBPT) Gaiduk et al (2018 Nat. Commun. 9 247) predicted an IP of 10.2 eV and EA of 0.2 eV, resulting in an electronic band gap (i.e. electronic gap (IP-EA) as measured by photoelectron spectroscopy) of about 10 eV, redefining the widely cited experimental gap of 8.7 eV in literature. In the present work, we show that GW self-consistency and an implicit vertex correction in MBPT considerably affect recently reported EA values by Gaiduk et al (2018 Nat. Commun. 9 247) by about 1 eV. Furthermore, the choice of pseudo-potential is critical for an accurate determination of the absolute band positions. Consequently, the self-consistent GW approach with an implicit vertex correction based on projector augmented wave (PAW) method on top of quantum water structures predicts an IP of 10.2, an EA of 1.1, a fundamental gap of 9.1 eV and an exciton binding (Eb) energy of 0.9 eV for the first absorption band of liquid water via the Bethe–Salpeter equation (BSE). Only within such a self-consistent approach a simultanously accurate prediction of IP, EA, Eg, Eb is possible.

  19. Single-particle spectra and magnetic field effects within precursor superconductivity

    International Nuclear Information System (INIS)

    Pieri, P.; Pisani, L.; Strinati, G.C.; Perali, A.

    2004-01-01

    We study the single-particle spectra below the superconducting critical temperature from weak to strong coupling within a precursor superconductivity scenario. The spectral-weight function is obtained from a self-energy that includes pairing-fluctuations within a continuum model representing the hot spots of the Brillouin zone. The effects of strong magnetic fields on the pseudogap temperature are also discussed within the same scenario

  20. Superconductivity induced by extremely high pressures in organic Mott-insulator β'-(BEDT-TTF)2IBrCl

    International Nuclear Information System (INIS)

    Kano, M; Uchiyama, K; Taniguchi, H; Hedo, M; Matsubayashi, K; Uwatoko, Y

    2009-01-01

    Previous research revealed that, at a pressure of 8.2 GPa, β'-(BEDT-TTF)2ICl2 possesses the highest transition temperature (T C ) among the organic conductors[1]. In the present work, transport studies under extremely high pressure of up to 10.0 GPa, using a cubic anvil press are reported for a related material, β'-(BEDT-TTF)2IBrCl which is an organic Mott-insulator in ambient pressure. Superconductivity with the highest T c (8.5 K, onset) was observed at P = 8.6 GPa.

  1. The gauge-independent QCD effective charge

    International Nuclear Information System (INIS)

    Watson, N.J.

    1997-01-01

    It is shown how the QED concept of a gauge-, scale- and scheme-independent one-loop effective charge can be extended directly at the diagrammatic level to QCD, thus justifying explicitly the ''naive non-abelianization'' prescription used in renormalon calculus. It is first argued that, for on-shell external fields and at the strictly one-loop level, the required gluon self-energy-like function is precisely that obtained from S-matrix elements via the pinch technique. The generalization of the pinch technique to explicitly off-shell processes is then introduced. It is shown how, as a result of a fundamental cancellation among conventional perturbation theory diagrams, encoded in the QCD Ward identities, the pinch technique one-loop gluon self-energy iΠ μν ab (q) remains gauge-independent and universal regardless of the fact that the ''external'' fields in the given process are off-shell. This demonstration involves a simple technique enabling the isolation, in an arbitrary gauge, of iΠ μν ab (q) from subclasses of up to several hundred diagrams at once. Furthermore, it is shown how this one-loop cancellation mechanism iterates for the subclasses of n-loop diagrams containing implicitly the Dyson chains of n one-loop self-energies iΠ μν ab (q). The gauge cancellation required for the Dyson summation of iΠ μν ab (q) is thus demonstrated explicitly in a general class of ghost-free gauges for all orders n. (orig.)

  2. The gauge-independent QCD effective charge

    International Nuclear Information System (INIS)

    Watson, N.J.

    1999-01-01

    It is shown how the QCD concept of a gauge-, scale-and scheme-independent one-loop effective charge can be extended directly at the diagrammatic level to QCD, thus justifying explicitly the 'naive non-abelialization' prescription used in renormalon calculus. It is first argued that, for one-shell external fields and at the strictly one-loop level, the required gluon self-energy-like function is precisely that obtained from S-matrix elements via the pinch technique. The generalization of the pinch technique to explicitly off-shell processes is then introduced. It is shown how, as a result of a fundamental cancellation among conventional perturbation theory diagrams encoded in the QCD Ward identities, the pinch technique one-loop gluon self-energy iΠ μν ab (q) remains gauge-independent and universal regardless of the fact that the 'external' fields in the given process are off-shell. This demonstration involves a simple technique enabling the isolation in a arbitrary gauge, of iΠ μν ab (q) from subclasses of up to several hundreds diagrams at once. Furthermore, it is shown how this one-loop cancellation mechanism iterates for the subclasses of n-loop diagrams containing implicitly the Dyson chains of n-loop self energies iΠ μν ab (q). The gauge cancellation required for the Dyson summation of iΠ μν ab (q) is thus demonstrated explicitly in the class of ghost-free gauges for all orders n. (authors)

  3. Relativistic theory of the Lamb shift based on self energy

    International Nuclear Information System (INIS)

    Barut, A.O.; Salamin, Y.I.

    1987-07-01

    A study is made to evaluate the Lamb shift to all orders in (Zα) using relativistic Dirac Coulomb wavefunctions and without resorting to the dipole approximation. Use is made of the angular integrals and spins sums performed elsewhere exactly. A regularization procedure is given that makes the sum over the positive and negative energy states finite. Finally, the energy shift ΔE n LS is given in terms of an integral that may be done numerically. (author). 19 refs

  4. The effect of six-point one-particle reducible local interactions in the dual fermion approach

    International Nuclear Information System (INIS)

    Katanin, A A

    2013-01-01

    We formulate the dual fermion approach for strongly correlated electronic systems in terms of the lattice and dual effective interactions, obtained by using the covariation splitting formula. This allows us to consider the effect of six-point one-particle reducible interactions, which are usually neglected by the dual fermion approach. We show that the consideration of one-particle reducible six-point (as well as higher order) vertices is crucially important for the diagrammatic consistency of this approach. In particular, the relation between the dual and lattice self-energy, derived in the dual fermion approach, implicitly accounts for the effect of the diagrams, containing six-point and higher order local one-particle reducible vertices, and should be applied with caution, if these vertices are neglected. Apart from that, the treatment of the self-energy feedback is also modified by six-point and higher order vertices; these vertices are also important to account for some non-local corrections to the lattice self-energy, which have the same order in the local four-point vertices as the diagrams usually considered in the approach. These observations highlight an importance of six-point and higher order vertices in the dual fermion approach, and call for the development of new schemes of treatment of non-local fluctuations, which are based on one-particle irreducible quantities. (paper)

  5. Effect of Holstein phonons on the electronic properties of graphene

    International Nuclear Information System (INIS)

    Stauber, T; Peres, N M R

    2008-01-01

    We obtain the self-energy of the electronic propagator due to the presence of Holstein polarons within the first Born approximation. This leads to a renormalization of the Fermi velocity of 1%. We further compute the optical conductivity of the system at the Dirac point and at finite doping within the Kubo formula. We argue that the effects due to Holstein phonons are negligible and that the Boltzmann approach, which does not include inter-band transitions and can thus not treat optical phonons due to their high energy of ℎω 0 ∼ 0.1-0.2 eV, remains valid

  6. Effect of Holstein phonons on the electronic properties of graphene

    OpenAIRE

    Stauber, T.; Peres, N. M. R.

    2007-01-01

    We obtain the self-energy of the electronic propagator due to the presence of Holstein polarons within the first Born approximation. This leads to a renormalization of the Fermi velocity of one percent. We further compute the optical conductivity of the system at the Dirac point and at finite doping within the Kubo-formula. We argue that the effects due to Holstein phonons are negligible and that the Boltzmann approach which does not include inter-band transition and can thus not treat optica...

  7. Status of effective potential calculations

    CERN Document Server

    Quiros, M.

    1995-01-01

    We review various effective potential methods which have been useful to compute the Higgs mass spectrum and couplings of the minimal supersymmetric standard model. We compare results where all-loop next-to-leading-log corrections are resummed by the renormalization group, with those where just the leading-log corrections are kept. Pole masses are obtained from running masses by addition of convenient self-energy diagrams. Approximate analytical expressions are worked out, providing an excellent approximation to the numerical results which include all next-to-leading-log terms. An appropriate treatment of squark decoupling allows to consider large values of the stop and/or sbottom mixing parameters and thus fix a reliable upper bound on the mass of the lightest CP-even Higgs boson mass.

  8. Multi-gap superconductivity in MgB2: Magneto-Raman spectroscopy

    International Nuclear Information System (INIS)

    Blumberg, G.; Mialitsin, A.; Dennis, B.S.; Zhigadlo, N.D.; Karpinski, J.

    2007-01-01

    Electronic Raman scattering studies on MgB 2 single crystals as a function of excitation and polarization have revealed three distinct superconducting features: a clean gap below 37 cm -1 and two coherence peaks at 109 and 78 cm -1 which we identify as the superconducting gaps in π- and σ-bands and as the Leggett's collective mode arising from the fluctuation in the relative phase between two superconducting condensates residing on corresponding bands. The temperature and field dependencies of the superconducting features have been established. A phononic Raman scattering study of the E 2g boron stretching mode anharmonicity and of superconductivity induced self-energy effects is presented. We show that anharmonic two phonon decay is mainly responsible for the unusually large linewidth of the E 2g mode. We observe ∼2.5% hardening of the E 2g phonon frequency upon cooling into the superconducting state and estimate the electron-phonon coupling strength associated with this renormalization

  9. Possible unifying effect of the dynamic theory

    International Nuclear Information System (INIS)

    Williams, P.E.

    1983-05-01

    This report presents the tentative results of recent research during which a neocoulombic electrostatic force of the form (k/r 2 )(1-lambda/r) exp(-lambda/r) was derived. This neocoulombic force offers a possible alternative explanation of nuclear phenomena without the necessity for postulating the existence of nuclear forces, and it allows the prediction of nuclear masses. The result is a view of physics in a five-dimensional manifold of space, time, and mass density in which the gauge field includes gravitational and electromagnetic components coupled by a single system of eight differential equations, quantum effects occur as the result of a restrictive assumption, and nuclear phenomena result from the new form for the electrostatic force. Also, the geometrical effect on the unit of action in quantum mechanics is presented, the self-energy of charged particles is calculated, and experimental tests of the theory are suggested

  10. Accounting for many-body correlation effects in the calculation of the valence band photoelectron emission spectra of ferromagnets

    International Nuclear Information System (INIS)

    Minar, J.; Chadov, S.; Ebert, H.; Chioncel, L.; Lichtenstein, A.; De Nadai, C.; Brookes, N.B.

    2005-01-01

    The influence of dynamical correlation effects on the valence band photoelectron emission of ferromagnetic Fe, Co and Ni has been investigated. Angle-resolved as well as angle-integrated valence band photoelectron emission spectra were calculated on the basis of the one-particle Green's function, which was obtained by using the fully relativistic Korringa-Kohn-Rostoker method. The correlation effects have been included in terms of the electronic self-energy which was calculated self-consistently within Dynamical Mean-Field Theory (DMFT). In addition a theoretical approach to calculate high-energy angle-resolved valence band photoelectron emission spectra is presented

  11. Pairing fluctuation effects on the single-particle spectra for the superconducting state

    International Nuclear Information System (INIS)

    Pieri, P.; Pisani, L.; Strinati, G.C.

    2004-01-01

    Single-particle spectra are calculated in the superconducting state for a fermionic system with an attractive interaction, as functions of temperature and coupling strength from weak to strong. The fermionic system is described by a single-particle self-energy that includes pairing-fluctuation effects in the superconducting state. The theory reduces to the ordinary BCS approximation in weak coupling and to the Bogoliubov approximation for the composite bosons in strong coupling. Several features of the single-particle spectral function are shown to compare favorably with experimental data for cuprate superconductors

  12. Many-body effects in the gain spectra of highly excited quantum-dot lasers

    International Nuclear Information System (INIS)

    Schneider, H. C.; Chow, W. W.; Koch, S. W.

    2001-01-01

    Optical gain spectra are computed for quantum dots under high excitation conditions, where there is a non-negligible two-dimensional carrier density surrounding the dots. Using a screened Hartree-Fock theory to describe the influence of the Coulomb interaction, we find different self-energy shifts for the dot and quantum-well transitions. Furthermore, in contrast to the result for quantum-well and bulk systems, the peak gain at the quantum-dot transition computed including Coulomb effects is reduced from its free carrier value

  13. Electromagnetic effects of neutrinos in an electron gas

    International Nuclear Information System (INIS)

    Nieves, Jose F.; Sahu, Sarira

    2005-01-01

    We study the electromagnetic properties of a system that consists of an electron background and a neutrino gas that may be moving or at rest, as a whole, relative to the background. The photon self-energy for this system is characterized by the usual transverse and longitudinal polarization functions, and two additional ones which are the focus of our calculations, that give rise to birefringence and anisotropic effects in the photon dispersion relations. Expressions for them are obtained, which depend on the neutrino number densities and involve momentum integrals over the electron distribution functions, and are valid for any value of the photon momentum and general conditions of the electron gas. Those expressions are evaluated explicitly for several special cases and approximations which are generally useful in astrophysical and cosmological settings. Besides studying the photon dispersion relations, we consider the macroscopic electrodynamic equations for this system, which involve the standard dielectric and permeability constants plus two additional ones related to the photon self-energy functions. As an illustration, the equations are used to discuss the evolution of a magnetic field perturbation in such a medium. This particular phenomena has also been considered in a recent work by Semikoz and Sokoloff as a mechanism for the generation of large-scale magnetic fields in the early Universe as a consequence of the neutrino-plasma interactions, and allows us to establish contact with a specific application in a well defined context, with a broader scope and from a very different point of view

  14. Many body effects in nuclear matter QCD sum rules

    Science.gov (United States)

    Drukarev, E. G.; Ryskin, M. G.; Sadovnikova, V. A.

    2017-12-01

    We calculate the single-particle nucleon characteristics in symmetric nuclear matter with inclusion of the 3N and 4N interactions. We calculated the contribution of the 3N interactions earlier, now we add that of the 4N ones. The contribution of the 4N forces to nucleon self energies is expressed in terms of the nonlocal scalar condensate (d = 3) and of the configurations of the vector-scalar and the scalar-scalar quark condensates (d = 6) in which two diquark operators act on two different nucleons of the matter.These four-quark condensates are obtained in the model-independent way. The density dependence of the nucleon effective mass, of the vector self energy and of the single-particle potential energy are obtained. We traced the dependence of the nucleon characteristics on the actual value of the pion-nucleon sigma term. We obtained also the nucleon characteristics in terms of the quasifree nucleons, with the noninteracting nucleons surrounded by their pion clouds as the starting point. This approach leads to strict hierarchy of the many body forces.

  15. Effective pion--nucleon interaction in nuclear matter

    International Nuclear Information System (INIS)

    Celenza, L.S.; Liu, L.C.; Nutt, W.; Shakin, C.M.

    1976-01-01

    We discuss the modification of the interaction between a pion and a nucleon in the presence of an infinite medium of nucleons (nuclear matter). The theory presented here is covariant and is relevant to the calculation of the pion--nucleus optical potential. The specific effects considered are the modifications of the nucleon propagator due to the Pauli principle and the modification of the pion and nucleon propagators due to collisions with nucleons of the medium. We also discuss in detail the pion self-energy in the medium, paying close attention to off-shell effects. These latter effects are particularly important because of the rapid variation with energy of the fundamental pion--nucleon interaction. Numerical results are presented, the main feature being the appearance of a significant damping width for the (3, 3) resonance

  16. The effect of particle-hole interaction on the XPS core-hole spectrum

    International Nuclear Information System (INIS)

    Ohno, Masahide; Sjoegren, Lennart

    2004-01-01

    How the effective particle-hole interaction energy, U, or the polarization effect on a secondary electron in a final two-hole one-particle (2h1p) state created by the Coster-Kronig (CK) transition can solely affect the density of the CK particle states and consequently the core-hole spectral function, is discussed. The X-ray photoelectron spectroscopy (XPS) core-hole spectrum is predominantly governed by the unperturbed initial core-hole energy relative to the zero-point energy. At the latter energy, the real part of the initial core-hole self-energy becomes zero (no relaxation energy shift) and the imaginary part (the lifetime broadening) approximately maximizes. The zero-point energy relative to the double-ionization threshold energy is governed by the ratio of U relative to the bandwidth of the CK continuum. As an example, we study the 5p XPS spectra of atomic Ra (Z=88), Th (Z=90) and U (Z=92). The spectra are interpreted in terms of the change in the unperturbed initial core-hole energy relative to the zero-point energy. We explain why in general an ab initio atomic many-body calculation can provide an overall good description of solid-state spectra predominantly governed by the atomic-like localized core-hole dynamics. We explain this in terms of the change from free atom to metal in both U and the zero-point energy (self-energy)

  17. Metal-insulator transition and superconductivity induced by Rh doping in the binary pnictides RuPn (Pn=P, As, Sb)

    Science.gov (United States)

    Hirai, Daigorou; Takayama, Tomohiro; Hashizume, Daisuke; Takagi, Hidenori

    2012-04-01

    Binary ruthenium pnictides, RuP and RuAs, with an orthorhombic MnP structure, were found to show a metal to a nonmagnetic insulator transition at TMI = 270 and 200 K, respectively. In the metallic region above TMI, a structural phase transition, accompanied with a weak anomaly in the resistivity and the magnetic susceptibility, indicative of a pseudogap formation, was identified at Ts = 330 and 280 K, respectively. These two transitions were suppressed by substituting Ru with Rh. We found superconductivity with a maximum Tc = 3.7 and 1.8 K in a narrow composition range around the critical point for the pseudogap phase, Rh content xc = 0.45 and 0.25 for Ru1-xRhxP and Ru1-xRhxAs, respectively, which may provide us with a nonmagnetic route to superconductivity at a quantum critical point.

  18. Orbital effect of the magnetic field in dynamical mean-field theory

    Science.gov (United States)

    Acheche, S.; Arsenault, L.-F.; Tremblay, A.-M. S.

    2017-12-01

    The availability of large magnetic fields at international facilities and of simulated magnetic fields that can reach the flux-quantum-per-unit-area level in cold atoms calls for systematic studies of orbital effects of the magnetic field on the self-energy of interacting systems. Here we demonstrate theoretically that orbital effects of magnetic fields can be treated within single-site dynamical mean-field theory with a translationally invariant quantum impurity problem. As an example, we study the one-band Hubbard model on the square lattice using iterated perturbation theory as an impurity solver. We recover the expected quantum oscillations in the scattering rate, and we show that the magnetic fields allow the interaction-induced effective mass to be measured through the single-particle density of states accessible in tunneling experiments. The orbital effect of magnetic fields on scattering becomes particularly important in the Hofstadter butterfly regime.

  19. Transport through a vibrating quantum dot: Polaronic effects

    International Nuclear Information System (INIS)

    Koch, T; Alvermann, A; Fehske, H; Loos, J; Bishop, A R

    2010-01-01

    We present a Green's function based treatment of the effects of electron-phonon coupling on transport through a molecular quantum dot in the quantum limit. Thereby we combine an incomplete variational Lang-Firsov approach with a perturbative calculation of the electron-phonon self energy in the framework of generalised Matsubara Green functions and a Landauer-type transport description. Calculating the ground-state energy, the dot single-particle spectral function and the linear conductance at finite carrier density, we study the low-temperature transport properties of the vibrating quantum dot sandwiched between metallic leads in the whole electron-phonon coupling strength regime. We discuss corrections to the concept of an anti-adiabatic dot polaron and show how a deformable quantum dot can act as a molecular switch.

  20. Effect of electron-photon interaction on the knight shift

    International Nuclear Information System (INIS)

    Tripathi, G.S.; Misra, C.M.; Tripathi, P.; Misra, P.K.

    1990-01-01

    The effect of electron-phonon interaction is considered on the spin (K s ), orbital (K o ) and spin-orbit (K so ) contributions to the Knight shift. In case of K s , it is found that the modifications caused due to the magnetic field dependence of electron self-energy in the presence of electron-phonon interaction is cancelled by the electron-phonon mass enhancement. However, in the presence of both electron-electron and electron-phonon interactions, the exchange enhancement parameter α is modified to α(1+γ) -1 where γ is the electron-phonon mass enhancement parameter. The orbital and spin-orbital contributions are mainly modified through the changes in the one-electron energies and wave functions. (orig.)

  1. Quark Loop Effects on Dressed Gluon Propagator in Framework of Global Color Symmetry Model

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; SUN Wei-Min

    2006-01-01

    Based on the global color symmetry model (GCM), a method for obtaining the quark loop effects on the dressed gluon propagator in GCM is developed. In the chiral limit, it is found that the dressed gluon propagator containing the quark loop effects in the Nambu-Goldstone and Wigner phases are quite different. In solving the quark self-energy functions in the two different phases and subsequent study of bag constant one should use the above dressed gluon propagator as input. The above approach for obtaining the current quark mass effects on the dressed gluon propagator is quite general and can also be used to calculate the chemical potential dependence of the dressed gluon propagator.

  2. Effects of a strict cutoff on Quantum Field Theory

    International Nuclear Information System (INIS)

    Sturnfield, J.F.

    1987-01-01

    Standard Quantum Field Theory has a number of integrals which are infinite. Although these are eliminated for some cases by renormalization, this aspect of the theory is not fully satisfactory. A number of theories with fundamental lengths have been introduced as alternatives and it would be useful to be able to distinguish between them. In particular, the effects that a strict cutoff would have on Quantum Field Theory is studied. It is noted that care must be taken in the method used to apply a strict cutoff. This lead to considering a theory where the cutoffs are defined by restricting each internal line. This theory is only piece-wise analytic. The resulting scattering matrix is frame dependent, yet the theory still satisfies the special relativity view that all frames are subjectively identical. The renormalization of this theory is finite. The change in mass from the electron self-energy will be a spinor operator. The main distinctions of this theory from standard theory will occur at super high energies. New poles and resonances which arise from new endpoint singularities will be found. The locations of these singularities will be frame dependent. Some of these singularities will correspond to creations or interactions of the normal particles with tachyons. It will be shown that for the one loop diagram, the form of the cutoff singularities are closely related to the standard singularities. When there is more than one loop, there can appear some new type of behavior. In particular, a cube root type of behavior in the two loop self-energy diagram will be found. Also the asymptotic behavior of the ladder diagram is studied

  3. Optical absorption spectra of semiconductors and insulators: ab initio calculation of many-body effects

    International Nuclear Information System (INIS)

    Albrecht, Stefan

    1999-01-01

    A method for the inclusion of self-energy and excitonic effects in first-principle calculations of absorption spectra, within the state-of-the-art plane wave pseudopotential approach, is presented. Starting from a ground state calculation, using density functional theory (DFT) in the local density approximation (LDA), we correct the exchange-correlation potential of DFT-LDA with the self-energy applying Hedin's GW approximation to obtain the physical quasiparticles states. The electron-hole interaction is treated solving an effective two-particle equation, which we derive from Hedin's coupled integral equations, leading to the fundamental Bethe-Salpeter equation in an intermediate step. The interaction kernel contains the screened electron-hole Coulomb interaction and the electron-hole exchange effects, which reflect the microscopic structure of the system and are thus also called local-field effects. We obtain the excitonic eigenstates through diagonalization. This allows us a detailed analysis of the optical properties. The application of symmetry properties enables us to reduce the size of the two-particle Hamiltonian matrix, thus minimizing the computational effort. We apply our method to silicon, diamond, lithium oxide and the sodium tetramer. Good agreement with experiment is obtained for the absorption spectra of Si and diamond, the static dielectric constant of diamond, and for the onset of optical absorption of Li 2 O due to discrete bound excitons. We discuss various approximations of our method and show the strong mixing of independent particle transitions to a bound excitonic state in the Na 4 cluster. The influence of ground state calculations on optical spectra is investigated under particular consideration of the pseudopotential generation and we discuss the use of different Brillouin zone point sampling schemes for spectral calculations. (author) [fr

  4. Many-body theory of effective mass in degenerate semiconductors

    Science.gov (United States)

    Tripathi, G. S.; Shadangi, S. K.

    2018-03-01

    We derive the many-body theory of the effective mass in the effective mass representation (EMR). In the EMR, we need to solve the equation of motion of an electron in the presence of electron-electron interactions, where the wavefunction is expanded over a complete set of Luttinger-Kohn wavefunctions. We use the Luttinger-Ward thermodynamic potential and the Green’s function perturbation to derive an expression for the band effective mass by taking into account the electron-electron interactions. Both quasi-particle and the correlation contributions are considered. We show that had we considered only the quasi-particle contribution, we would have missed important cancellations. Thus the correlated motion of electrons has important effects in the renormalization of the effective mass. Considering the exchange self-energy in the band model, we derive a tractable expression for the band effective mass. We apply the theory to n-type degenerate semiconductors, PbTe and SnTe, and analyze the impact of the theory on the anisotropic effective mass of the conduction bands in these systems.

  5. Consistent method of truncating the electron self-energy in nonperturbative QED

    International Nuclear Information System (INIS)

    Rembiesa, P.

    1986-01-01

    A nonperturbative method of solving the Dyson-Schwinger equations for the fermion propagator is considered. The solution satisfies the Ward-Takahashi identity, allows multiplicative regularization, and exhibits a physical-mass pole

  6. Large momentum expansion of two-loop self-energy diagrams with arbitrary masses

    International Nuclear Information System (INIS)

    Davydychev, A.I.; Smirnov, V.A.; Tausk, J.B.

    1993-01-01

    For two-loop two-point diagrams with arbitrary masses, an algorithm to derive the asymptotic expansion at large external momentum squared is constructed. By using a general theorem on asymptotic expansions of Feynman diagrams, the coefficients of the expansion are calculated analytically. For some two-loop diagrams occurring in the Standard Model, comparison with results of numerical integration shows that our expansion works well in the region above the highest physical threshold. (orig.)

  7. Small-threshold behaviour of two-loop self-energy diagrams: two-particle thresholds

    International Nuclear Information System (INIS)

    Berends, F.A.; Davydychev, A.I.; Moskovskij Gosudarstvennyj Univ., Moscow; Smirnov, V.A.; Moskovskij Gosudarstvennyj Univ., Moscow

    1996-01-01

    The behaviour of two-loop two-point diagrams at non-zero thresholds corresponding to two-particle cuts is analyzed. The masses involved in a cut and the external momentum are assumed to be small as compared to some of the other masses of the diagram. By employing general formulae of asymptotic expansions of Feynman diagrams in momenta and masses, we construct an algorithm to derive analytic approximations to the diagrams. In such a way, we calculate several first coefficients of the expansion. Since no conditions on relative values of the small masses and the external momentum are imposed, the threshold irregularities are described analytically. Numerical examples, using diagrams occurring in the standard model, illustrate the convergence of the expansion below the first large threshold. (orig.)

  8. Chiral symmetry breaking in QED3: bifurcation of the fermionic self-energy

    International Nuclear Information System (INIS)

    Almeida, L.D.; Natale, A.A.

    1989-01-01

    The existence of a bifurcation point in the Scwinger-Dyson equation of 2+1 dimensional quantum electrodynamics with N fermions, is studied. It is found an evidence for the existence of a critical behavior, such that chiral symmetry breaking may occur only for a small number of flavors. (author) [pt

  9. Short range correlations in the pion s-wave self-energy of pionic atoms

    OpenAIRE

    Salcedo, L. L.; Holinde, K.; Oset, E.; Schütz, C.

    1995-01-01

    We evaluate the contribution of second order terms to the pion-nucleus s-wave optical potential of pionic atoms generated by short range nuclear correlation. The corrections are sizeable because they involve the isoscalar s-wave $\\pi N$ amplitude for half off-shell situations where the amplitude is considerably larger than the on-shell one. In addition, the s-wave optical potential is reanalyzed by looking at all the different conventional contributions together lowest order, Pauli corrected ...

  10. Correlation effects on the nonmesonic weak decay of the Λ hyperon in nuclear matter

    Science.gov (United States)

    Robertson, N. J.; Dickhoff, W. H.

    2005-08-01

    The nonmesonic weak decay of a Λ hyperon is studied in nuclear matter. Special emphasis is placed on a consistent treatment of correlations introduced by the strong interaction on its weak counterpart. The latter is described by the exchange of mesons between the initial ΛN state and the final NN one. The weak decay is studied in terms of the weak self-energy, which allows a systematic evaluation of short-range and tensor correlation effects that are determined by a realistic hyperon-nucleon interaction. The admixture of ΣN components through the strong interaction is also included in the calculation of the Λ decay properties. Calculations for the ratio of the neutron-induced partial width to the corresponding proton-induced one, Γn/Γp, are discussed in connection with recent experimental results.

  11. Cobalt adatoms on graphene: Effects of anisotropies on the correlated electronic structure

    Science.gov (United States)

    Mozara, R.; Valentyuk, M.; Krivenko, I.; Şaşıoǧlu, E.; Kolorenč, J.; Lichtenstein, A. I.

    2018-02-01

    Impurities on surfaces experience a geometric symmetry breaking induced not only by the on-site crystal-field splitting and the orbital-dependent hybridization, but also by different screening of the Coulomb interaction in different directions. We present a many-body study of the Anderson impurity model representing a Co adatom on graphene, taking into account all anisotropies of the effective Coulomb interaction, which we obtained by the constrained random-phase approximation. The most pronounced differences are naturally displayed by the many-body self-energy projected onto the single-particle states. For the solution of the Anderson impurity model and analytical continuation of the Matsubara data, we employed new implementations of the continuous-time hybridization expansion quantum Monte Carlo and the stochastic optimization method, and we verified the results in parallel with the exact diagonalization method.

  12. Complete two-loop effective potential approximation to the lightest Higgs scalar boson mass in supersymmetry

    International Nuclear Information System (INIS)

    Martin, Stephen P.

    2003-01-01

    I present a method for accurately calculating the pole mass of the lightest Higgs scalar boson in supersymmetric extensions of the standard model, using a mass-independent renormalization scheme. The Higgs scalar self-energies are approximated by supplementing the exact one-loop results with the second derivatives of the complete two-loop effective potential in Landau gauge. I discuss the dependence of this approximation on the choice of renormalization scale, and note the existence of particularly poor choices, which fortunately can be easily identified and avoided. For typical input parameters, the variation in the calculated Higgs boson mass over a wide range of renormalization scales is found to be of the order of a few hundred MeV or less, and is significantly improved over previous approximations

  13. Casimir effect: The classical limit

    International Nuclear Information System (INIS)

    Feinberg, J.; Mann, A.; Revzen, M.

    2001-01-01

    We analyze the high temperature (or classical) limit of the Casimir effect. A useful quantity which arises naturally in our discussion is the 'relative Casimir energy', which we define for a configuration of disjoint conducting boundaries of arbitrary shapes, as the difference of Casimir energies between the given configuration and a configuration with the same boundaries infinitely far apart. Using path integration techniques, we show that the relative Casimir energy vanishes exponentially fast in temperature. This is consistent with a simple physical argument based on Kirchhoff's law. As a result the 'relative Casimir entropy', which we define in an obviously analogous manner, tends, in the classical limit, to a finite asymptotic value which depends only on the geometry of the boundaries. Thus the Casimir force between disjoint pieces of the boundary, in the classical limit, is entropy driven and is governed by a dimensionless number characterizing the geometry of the cavity. Contributions to the Casimir thermodynamical quantities due to each individual connected component of the boundary exhibit logarithmic deviations in temperature from the behavior just described. These logarithmic deviations seem to arise due to our difficulty to separate the Casimir energy (and the other thermodynamical quantities) from the 'electromagnetic' self-energy of each of the connected components of the boundary in a well defined manner. Our approach to the Casimir effect is not to impose sharp boundary conditions on the fluctuating field, but rather take into consideration its interaction with the plasma of 'charge carriers' in the boundary, with the plasma frequency playing the role of a physical UV cutoff. This also allows us to analyze deviations from a perfect conductor behavior

  14. Medium effects in strange quark matter and strange stars

    International Nuclear Information System (INIS)

    Schertler, K.; Greiner, C.; Thoma, M.H.

    1997-01-01

    We investigate the properties of strange quark matter at zero temperature including medium effects. The quarks are considered as quasiparticles which acquire an effective mass generated by the interaction with the other quarks of the dense system. The effective quark masses are derived from the zero momentum limit of the dispersion relations following from an effective quark propagator obtained from resumming one-loop self-energy diagrams in the hard dense loop approximation. This leads to a thermodynamic self-consistent description of strange quark matter as an ideal Fermi gas of quasiparticles. Within this approach we find that medium effects reduce the overall binding energy with respect to 56 Fe of strange quark matter. For typical values of the strong coupling constant (α s >or∼1) strange quark matter is not absolutely stable. The application to pure strange quark matter stars shows that medium effects have, nevertheless, no impact on the mass-radius relation of the stars. However, a phase transition to hadronic matter at the surface of the stars becomes more likely. (orig.)

  15. Quantum inelastic electron-vibration scattering in molecular wires: Landauer-like versus Green's function approaches and temperature effects

    International Nuclear Information System (INIS)

    Ness, H

    2006-01-01

    In this paper, we consider the problem of inelastic electron transport in molecular systems in which both electronic and vibrational degrees of freedom are considered on the quantum level. The electronic transport properties of the corresponding molecular nanojunctions are obtained by means of a non-perturbative Landauer-like multi-channel inelastic scattering technique. The connections between this approach and other Green's function techniques that are useful in particular cases are studied in detail. The validity of the wide-band approximation, the effects of the lead self-energy and the dynamical polaron shift are also studied for a wide range of parameters. As a practical application of the method, we consider the effects of the temperature on the conductance properties of molecular breakjunctions in relation to recent experiments

  16. Complete set of essential parameters of an effective theory

    Science.gov (United States)

    Ioffe, M. V.; Vereshagin, V. V.

    2018-04-01

    The present paper continues the series [V. V. Vereshagin, True self-energy function and reducibility in effective scalar theories, Phys. Rev. D 89, 125022 (2014); , 10.1103/PhysRevD.89.125022A. Vereshagin and V. Vereshagin, Resultant parameters of effective theory, Phys. Rev. D 69, 025002 (2004); , 10.1103/PhysRevD.69.025002K. Semenov-Tian-Shansky, A. Vereshagin, and V. Vereshagin, S-matrix renormalization in effective theories, Phys. Rev. D 73, 025020 (2006), 10.1103/PhysRevD.73.025020] devoted to the systematic study of effective scattering theories. We consider matrix elements of the effective Lagrangian monomials (in the interaction picture) of arbitrary high dimension D and show that the full set of corresponding coupling constants contains parameters of both kinds: essential and redundant. Since it would be pointless to formulate renormalization prescriptions for redundant parameters, it is necessary to select the full set of the essential ones. This is done in the present paper for the case of the single scalar field.

  17. Interaction Induced Quantum Valley Hall Effect in Graphene

    Directory of Open Access Journals (Sweden)

    E. C. Marino

    2015-03-01

    Full Text Available We use pseudo-quantum electrodynamics in order to describe the full electromagnetic interaction of the p electrons in graphene in a consistent 2D formulation. We first consider the effect of this interaction in the vacuum polarization tensor or, equivalently, in the current correlator. This allows us to obtain the T→0 conductivity after a smooth zero-frequency limit is taken in Kubo’s formula. Thereby, we obtain the usual expression for the minimal conductivity plus corrections due to the interaction that bring it closer to the experimental value. We then predict the onset of an interaction-driven spontaneous quantum valley Hall effect below an activation temperature of the order of 2 K. The transverse (Hall valley conductivity is evaluated exactly and shown to coincide with the one in the usual quantum Hall effect. Finally, by considering the effects of pseudo-quantum electrodynamics, we show that the electron self-energy is such that a set of P- and T-symmetric gapped electron energy eigenstates are dynamically generated, in association with the quantum valley Hall effect.

  18. QED effects on individual atomic orbital energies

    Science.gov (United States)

    Kozioł, Karol; Aucar, Gustavo A.

    2018-04-01

    Several issues, concerning QED corrections, that are important in precise atomic calculations are presented. The leading QED corrections, self-energy and vacuum polarization, to the orbital energy for selected atoms with 30 ≤ Z ≤ 118 have been calculated. The sum of QED and Breit contributions to the orbital energy is analyzed. It has been found that for ns subshells the Breit and QED contributions are of comparative size, but for np and nd subshells the Breit contribution takes a major part of the QED+Breit sum. It has also, been found that the Breit to leading QED contributions ratio for ns subshells is almost independent of Z. The Z-dependence of QED and Breit+QED contributions per subshell is shown. The fitting coefficients may be used to estimate QED effects on inner molecular orbitals. We present results of our calculations for QED contributions to orbital energy of valence ns-subshell for group 1 and 11 atoms and discuss about the reliability of these numbers by comparing them with experimental first ionization potential data.

  19. Leptogenesis from loop effects in curved spacetime

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Jamie I.; Shore, Graham M. [Department of Physics, Swansea University,Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2016-04-05

    We describe a new mechanism — radiatively-induced gravitational leptogenesis — for generating the matter-antimatter asymmetry of the Universe. We show how quantum loop effects in C and CP violating theories cause matter and antimatter to propagate differently in the presence of gravity, and prove this is forbidden in flat space by CPT and translation symmetry. This generates a curvature-dependent chemical potential for leptons, allowing a matter-antimatter asymmetry to be generated in thermal equilibrium in the early Universe. The time-dependent dynamics necessary for leptogenesis is provided by the interaction of the virtual self-energy cloud of the leptons with the expanding curved spacetime background, which violates the strong equivalence principle and allows a distinction between matter and antimatter. We show here how this mechanism is realised in a particular BSM theory, the see-saw model, where the quantum loops involve the heavy sterile neutrinos responsible for light neutrino masses. We demonstrate by explicit computation of the relevant two-loop Feynman diagrams how the size of the radiative corrections relevant for leptogenesis becomes enhanced by increasing the mass hierarchy of the sterile neutrinos, and show how the induced lepton asymmetry may be sufficiently large to play an important rôle in determining the baryon-to-photon ratio of the Universe.

  20. Three-particle one-hole multiple scattering contribution to the nuclear effective interaction in mass-18 nuclei

    International Nuclear Information System (INIS)

    Bando, H.; Krenciglowa, E.M.; Ando, K.

    1979-01-01

    Within the systematic framework of the double partition approach, the three-particle one-hole multiple scattering and Q-box formalisms are combined to give the valence-linked and connected energy-independent effective interaction. All low-lying [2p+3p1h] contributions to the mass-18 effective interaction are evaluated using an essentially exact energy-dependent reaction matrix based on the Reid SC potential. The low-lying one-body field of the core nucleus is treated consistently with the underlying reaction matrix G through particle- and hole-line self-energy insertions. Center-of-mass motion, folded diagrams and starting energy dependence are properly taken into account throughout. The low-lying [2p+3p1h] correlations are strongly damped by self-energy insertions. By incorporating only the folded diagram contributions with origins in the low-lying space, the net effect of all low-lying [2p+3p1h] correlations is to give back the bare-G plus second-order core-polarization spectra which are found to be in respectable agreement with the experimental spectra. However, including the full folded diagram contribution, which has additional contributions from the high-lying space through the energy dependence of G, leads to final spectra which deviate sizably from experiment. The present results are conclusive in the sense that the treatment is essentially exact for low-lying [2p+3p1h] correlations which originate from the high-lying two-particle correlations through the reaction matrix G. (Auth.)

  1. The influence of band Jahn-Teller effect and magnetic order on the magneto-resistance in manganite systems

    Energy Technology Data Exchange (ETDEWEB)

    Rout, G.C., E-mail: gcr@iopb.res.i [Condensed Matter Physics Group, Department of Applied Physics and Ballistics, F.M. University, Balasore, Orissa 756019 (India); Parhi, Nilima [Department of Physics, M.P.C. (Autonomous) College, Baripada, Orissa 757001 (India); Behera, S.N. [Institute of Material Science, Bhubaneswar 751004 (India)

    2009-08-01

    A model calculation is presented in order to study the magneto-resistivity through the interplay between magnetic and structural transitions for the manganite systems. The model consists of an orbitally doubly degenerate conduction band and a periodic array of local moments of the t{sub 2g} electrons. The band electrons interact with the local t{sub 2g} electrons via the s-f hybridization. The phonons interact with the band electrons through static and dynamic band Jahn-Teller (J-T) interaction. The model Hamiltonian including the above terms is solved for the single particle Green's functions and the imaginary part of the self-energy gives the electron relaxation time. Thus the magneto-resistivity (MR) is calculated from the Drude formula. The MR effect is explained near the magnetic and structural transition temperatures.

  2. Aharonov-Casher effect and quantum transport in graphene based nano rings: A self-consistent Born approximation

    Science.gov (United States)

    Ghaderzadeh, A.; Rahbari, S. H. Ebrahimnazhad; Phirouznia, A.

    2018-03-01

    In this study, Rashba coupling induced Aharonov-Casher effect in a graphene based nano ring is investigated theoretically. The graphene based nano ring is considered as a central device connected to semi-infinite graphene nano ribbons. In the presence of the Rashba spin-orbit interaction, two armchair shaped edge nano ribbons are considered as semi-infinite leads. The non-equilibrium Green's function approach is utilized to obtain the quantum transport characteristics of the system. The relaxation and dephasing mechanisms within the self-consistent Born approximation is scrutinized. The Lopez-Sancho method is also applied to obtain the self-energy of the leads. We unveil that the non-equilibrium current of the system possesses measurable Aharonov-Casher oscillations with respect to the Rashba coupling strength. In addition, we have observed the same oscillations in dilute impurity regimes in which amplitude of the oscillations is shown to be suppressed as a result of the relaxations.

  3. Effect of tin doping on the optical properties of indium oxide films by a spray pyrolysis method

    International Nuclear Information System (INIS)

    Ibrahim Abu Talib; Muhammad Mat Salleh; Muhammad Yahya; Mod Noor Bader Sher

    1993-01-01

    Thin films of stannum doped indium oxide were deposited on glass by a X-ray pyrolysis method. The substrate temperature and the rate of flow of the carrier gas were fixed at 450 0 C and 2.5 litre/minute respectively during deposition. The dependence of the optical properties of the films on the doping concentration was studied. It is found that the transmission of the visible wavelengths (300 to 800 nm) through the films increases around 5% from 74.9% as the film was doped with 10% stannum. It is also found that the optical energy bandgap increases 0.2 eV from 3.16 to 3.36 eV by doping the film with 10% stannum. The increase is attributed to the Bernstein-Moss (1) and self-energy (2) effects

  4. Transport coefficients of Dirac ferromagnet: Effects of vertex corrections

    Science.gov (United States)

    Fujimoto, Junji

    2018-03-01

    As a strongly spin-orbit-coupled metallic model with ferromagnetism, we have considered an extended Stoner model to the relativistic regime, named Dirac ferromagnet in three dimensions. In a previous paper [J. Fujimoto and H. Kohno, Phys. Rev. B 90, 214418 (2014), 10.1103/PhysRevB.90.214418], we studied the transport properties giving rise to the anisotropic magnetoresistance (AMR) and the anomalous Hall effect (AHE) with the impurity potential being taken into account only as the self-energy. The effects of the vertex corrections (VCs) to AMR and AHE are reported in this paper. AMR is found not to change quantitatively when the VCs are considered, although the transport lifetime is different from the one-electron lifetime and the charge current includes additional contributions from the correlation with spin currents. The side-jump and the skew-scattering contributions to AHE are also calculated. The skew-scattering contribution is dominant in the clean case as can be seen in the spin Hall effect in the nonmagnetic Dirac electron system.

  5. Strong correlation effects in theoretical STM studies of magnetic adatoms

    Science.gov (United States)

    Dang, Hung T.; dos Santos Dias, Manuel; Liebsch, Ansgar; Lounis, Samir

    2016-03-01

    We present a theoretical study for the scanning tunneling microscopy (STM) spectra of surface-supported magnetic nanostructures, incorporating strong correlation effects. As concrete examples, we study Co and Mn adatoms on the Cu(111) surface, which are expected to represent the opposite limits of Kondo physics and local moment behavior, using a combination of density functional theory and both quantum Monte Carlo and exact diagonalization impurity solvers. We examine in detail the effects of temperature T , correlation strength U , and impurity d electron occupancy Nd on the local density of states. We also study the effective coherence energy scale, i.e., the Kondo temperature TK, which can be extracted from the STM spectra. Theoretical STM spectra are computed as a function of STM tip position relative to each adatom. Because of the multiorbital nature of the adatoms, the STM spectra are shown to consist of a complicated superposition of orbital contributions, with different orbital symmetries, self-energies, and Kondo temperatures. For a Mn adatom, which is close to half-filling, the STM spectra are featureless near the Fermi level. On the other hand, the quasiparticle peak for a Co adatom gives rise to strongly position-dependent Fano line shapes.

  6. One-particle reducibility in effective scattering theory

    International Nuclear Information System (INIS)

    Vereshagin, V.

    2016-01-01

    To construct the reasonable renormalization scheme suitable for the effective theories one needs to resolve the “problem of couplings” because the number of free parameters in a theory should be finite. Otherwise the theory would loose its predictive power. In the case of effective theory already the first step on this way shows the necessity to solve the above-mentioned problem for the 1-loop 2-leg function traditionally called self energy. In contrast to the customary renormalizable models the corresponding Feynman graph demonstrates divergencies that require introducing of an infinite number of prescriptions. In the recent paper [1] it has been shown that the way out of this difficulty requires the revision of the notion of one-particle reducibility. The point is that in effective scattering theory one can introduce two different notions: the graphic reducibility and the analytic one. Below we explain the main ideas of the paper [1] and recall some notions and definitions introduced earlier in [2] and [3

  7. Memory effects in the relaxation of nonideal plasmas

    International Nuclear Information System (INIS)

    Bonitz, M.; Kremp, D.; Scott, D.C.; Binder, R.

    1995-01-01

    Traditionally, nonequilibrium properties of many-particle systems have been quite successfully described on the basis of Markovian kinetic equations, such as the Landau, Boltzmann or Lenard-Balescu equation. However, these equations have to well-known principal defects: (1) they are applicable only to time-scales bigger than the correlation time τ cor and (2) they conserve only the kinetic energy but not the total energy of the system. The latter problem is important for strongly coupled systems, where the potential energy becomes comparable to the kinetic energy. Then, e.g. the equilibrium properties will be essentially determined by interaction effects. All thermodynamic quantities and transport coefficients will contain additional correlation contributions. These requirements make it necessary to consider generalized kinetic equations which conserve total energy like have been derived by Prigogine et al., Zubarev, Klimontovich and others. In this contribution we consider the proper non-Markovian generalization of the Boltzmann equation (binary collision approximation) and of the Landau equation (Born approximation). Many-particle effects, such as Pauli blocking, initial correlations, retardation (memory), energy broadening and self energy are included. The resulting generalized kinetic equations are discussed in detail. Important limiting cases, such as following from retardation or gradient expansions, are investigated

  8. Effect of thermal phonons on the superconducting transition temperature

    International Nuclear Information System (INIS)

    Leavens, C.R.; Talbot, E.

    1983-01-01

    There is no consensus in the literature on whether or not thermal phonons depress the superconducting transition temperature T/sub c/. In this paper it is shown by accurate numerical solution of the real-frequency Eliashberg equations for the pairing self-energy phi and renormalization function Z that thermal phonons in the kernel for phi raise T/sub c/ but those in Z lower it by a larger amount so that the net effect is to depress T/sub c/. (A previous calculation which ignored the effect of thermal phonons in phi overestimated the suppression of T/sub c/ by at least a factor of 3.) It is shown how to switch off the thermal phonons in the imaginary-frequency Eliashberg equations, exactly for Z and approximately for phi. The real-frequency and approximate imaginary-frequency results for the depression of T/sub c/ by thermal phonons are in very satisfactory agreement. Thermal phonons are found to depress the transition temperature of Nb 3 Sn by only 2%. It is estimated that the suppression of T/sub c/ by thermal phonons saturates at about 50% in the limit of very strong electron-phonon coupling

  9. Effective nucleon-nucleon interaction in the RPA

    International Nuclear Information System (INIS)

    Batista, E.F.; Carlson, B.V.; Conti, C. de; Frederico, T.

    2001-01-01

    The purpose of the present work is to study the properties of the effective nucleon-nucleon interaction, in a infinite system of mesons and baryons , using the relativistic Hartree-Fock-Bogoliubov approximation. To derive the RHFB equations in a systematic fashion, we use Dyson's equation to sum to all orders the self-consistent tadpole and exchange contributions to the extended baryon Green's function (the Gorkov propagator). The meson propagator is computed as a sum over ring diagrams which consist in repeated insertions of the lowest-order proper polarization graph. The sum is the diagrammatic equivalent of the relativistic random phase approximation (RPA) that describes the well-known collective modes. In the nuclear medium, the σ and ω propagators are linked because of scalar-vector mixing, a density-dependent effect that generates a coupling between the Dyson's equation for the meson propagators. We use the dressed meson propagator to obtain the effective interaction and investigate its effect on the 1 S 0 pairing in nuclear matter. The effective interaction has title effect on the self-energy mean field, since the latter is dominated by the Hartree contribution, which is determined by the free meson propagators. The pairing field, however, is obtained from an exchange term, in which the effective interaction can play an important role. As the polarization corrections to the meson propagators tend to increase the σ-meson mass and decrease the ω-meson mass, they result in an effective interaction which is more repulsive than the bare one. We would expect this to result in a decrease in the 1 S 0 pairing, similar to that seen in nonrelativistic calculations. (author)

  10. Coupled Dyson-Schwinger equations and effects of self-consistency

    International Nuclear Information System (INIS)

    Wu, S.S.; Zhang, H.X.; Yao, Y.J.

    2001-01-01

    Using the σ-ω model as an effective tool, the effects of self-consistency are studied in some detail. A coupled set of Dyson-Schwinger equations for the renormalized baryon and meson propagators in the σ-ω model is solved self-consistently according to the dressed Hartree-Fock scheme, where the hadron propagators in both the baryon and meson self-energies are required to also satisfy this coupled set of equations. It is found that the self-consistency affects the baryon spectral function noticeably, if only the interaction with σ mesons is considered. However, there is a cancellation between the effects due to the σ and ω mesons and the additional contribution of ω mesons makes the above effect insignificant. In both the σ and σ-ω cases the effects of self-consistency on meson spectral function are perceptible, but they can nevertheless be taken account of without a self-consistent calculation. Our study indicates that to include the meson propagators in the self-consistency requirement is unnecessary and one can stop at an early step of an iteration procedure to obtain a good approximation to the fully self-consistent results of all the hadron propagators in the model, if an appropriate initial input is chosen. Vertex corrections and their effects on ghost poles are also studied

  11. Effective interaction for relativistic mean-field theories of nuclear structure

    International Nuclear Information System (INIS)

    Ai, H.B.; Celenza, L.S.; Harindranath, A.; Shakin, C.M.

    1987-01-01

    We construct an effective interaction, which when treated in a relativistic Hartree-Fock approximation, reproduces rather accurately the nucleon self-energy in nuclear matter and the Migdal parameters obtained via relativistic Brueckner-Hartree-Fock calculations. This effective interaction is constructed by adding Born terms, describing the exchange of pseudoparticles, to the Born terms of the Dirac-Hartree-Fock analysis. The pseudoparticles have relatively large masses and either real or imaginary coupling constants. (For example, exchange of a pseudo-sigma with an imaginary coupling constant has the effect of reducing the scalar attraction arising from sigma exchange while exchange of a pseudo-omega with an imaginary coupling constant has the effect of reducing the repulsion arising from omega exchange. The terms beyond the Born term in the case of pion exchange are well simulated by pseudo-sigma exchange with a real coupling constant.) The effective interaction constructed here may be used for calculations of the properties of finite nuclei in a relativistic Hartree-Fock approximation

  12. Density functional approach to many-body effects in the optical response of atoms

    International Nuclear Information System (INIS)

    Zangwill, A.

    1981-01-01

    The purpose of this work is to present a new method for calculating the optical response of finite electronic system which is accurate, computationally simple, and lends itself to a ready physical interpretation of the results. This work is concerned with the so-called many-body effects which render an independent particle calculation inappropriate for comparison with experimental photoabsorption and photoemission cross sections. Polarization effects are included which describe the response of the system to an external probe and self-energy effects, which describe the dynamics and decay of a single particle state. This work, which essentially reintroduces the residual Coulomb interactions among the electrons, is confined to atoms. The method is a time-dependent local density approximation (TDLDA) and represents a natural generalization of the usual local density approximation to the ground state properties of a many electron system. Using standard first-order time-dependent perturbation theory, a self-consistent mean field theory is derived for an effective field which replaces the external field in the dipole matrix elements of the Golden Rule for photoabsorption. This effective field includes a contribution from an induced classical Coulomb field as well as an induced exchange-correlation field. This work successfully demonstrates the applicability of time-dependent generalization of the local density approximation to the practical calculation of the photo-response of atoms. For the rare gases, barium, cerium and copper are obtained cross sections in quantitative agreement with recent experiments

  13. Investigation of renormalization effects in high temperature cuprate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zabolotnyy, Volodymyr B.

    2008-04-16

    It has been found that the self-energy of high-T{sub C} cuprates indeed exhibits a well pronounced structure, which is currently attributed to coupling of the electrons either to lattice vibrations or to collective magnetic excitations in the system. To clarify this issue, the renormalization effects and the electronic structure of two cuprate families Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} and YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were chosen as the main subject for this thesis. With a simple example of an electronic system coupled to a collective mode unusual renormalization features observed in the photoemission spectra are introduced. It is shown that impurity substitution in general leads to suppression of the unusual renormalization. Finally an alternative possibility to obtain a purely superconducting surface of Y-123 via partial substitution of Y atoms with Ca is introduced. It is shown that renormalization in the superconducting Y-123 has similar strong momentum dependence as in the Bi-2212 family. It is also shown that in analogy to Bi-2212 the renormalization appears to have strong dependence on the doping level (no kinks for the overdoped component) and practically vanishes above T{sub C} suggesting that coupling to magnetic excitations fits much better than competing scenarios, according to which the unusual renormalization in ARPES spectra is caused by the coupling to single or multiple phononic modes. (orig.)

  14. Investigation of renormalization effects in high temperature cuprate superconductors

    International Nuclear Information System (INIS)

    Zabolotnyy, Volodymyr B.

    2008-01-01

    It has been found that the self-energy of high-T C cuprates indeed exhibits a well pronounced structure, which is currently attributed to coupling of the electrons either to lattice vibrations or to collective magnetic excitations in the system. To clarify this issue, the renormalization effects and the electronic structure of two cuprate families Bi 2 Sr 2 CaCu 2 O 8+δ and YBa 2 Cu 3 O 7-δ were chosen as the main subject for this thesis. With a simple example of an electronic system coupled to a collective mode unusual renormalization features observed in the photoemission spectra are introduced. It is shown that impurity substitution in general leads to suppression of the unusual renormalization. Finally an alternative possibility to obtain a purely superconducting surface of Y-123 via partial substitution of Y atoms with Ca is introduced. It is shown that renormalization in the superconducting Y-123 has similar strong momentum dependence as in the Bi-2212 family. It is also shown that in analogy to Bi-2212 the renormalization appears to have strong dependence on the doping level (no kinks for the overdoped component) and practically vanishes above T C suggesting that coupling to magnetic excitations fits much better than competing scenarios, according to which the unusual renormalization in ARPES spectra is caused by the coupling to single or multiple phononic modes. (orig.)

  15. Are Effective Properties Effective?

    International Nuclear Information System (INIS)

    Han, Ru; Ingber, Marc S.; Hsiao, S.-C.

    2008-01-01

    The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of dispersed-phase-reinforced composite materials are determined at the mesoscopic level using three-dimensional parallel boundary element simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach have been examined

  16. Dynamical screening of AMM and QED effects for large- Z hydrogen-like atoms

    Science.gov (United States)

    Roenko, A. A.; Sveshnikov, K. A.

    2018-01-01

    The effective interaction Δ U AMM of the anomalous magnetic moment (AMM) of an electron with the Coulomb field of an extended nucleus is analyzed. As soon as the q 2 dependence of the electron formfactor F 2( q 2)is taken into account from the beginning, the AMM is found to be dynamically screened at small distances of r ≪ 1/ m. The Δ U AMM effects on the low-lying electronic levels of a superheavy extended nucleus with Zα > 1are analyzed using the nonperturbative approach. The growth rate of the Δ U AMM contribution with increasing Z is shown to be essentially nonmonotonic. At the same time, the energy shifts of electronic levels in the vicinity of the threshold of the lower continuum monotonically decrease in the region Z ≫ Z cr,1 s . The latter result is generalized to the whole self-energy contribution to energy shifts of electronic levels, thus also referring to the possible behavior of QED radiative effects with virtual-photon exchange, considered beyond the framework of the perturbative expansion in Zα.

  17. Effects of welding on toughness of Mod. 9Cr-1Mo steel

    International Nuclear Information System (INIS)

    Ryu, W. S.; Kim, S. H.; Yoon, J. H.

    2008-01-01

    Nuclear energy is being seriously considered to meet the increasing demand for a world-wide energy supply without environmental effects. Generation IV reactors are being developed to produce a reliable energy safely and with an economic benefit. Since these new reactors require an elevated temperature, ferritic/martensitic steels are attracting attention as candidate materials for the reactor vessel of a very high temperature reactor (VHTR) and the cladding of a sodium fast reactor (SFR,) due to their high strength and thermal conductivity, low thermal expansion, and good resistance to corrosion. in recent years, new ferritic/martensitic steels have been developed for ultra supercritical fossil power plants. Advanced technologies for a steel fabrication have improved the elevated temperature properties of ferritic/martensitic steels to make them comparable with austenitic stainless steels. The microstructural stability of the pressure vessel, cladding and core structural materials of the VHTR and SCWR is very important. Welding process affects the microstructure and residual stress, so the toughness of ferritic/martensitic steels decreases in general. In this paper; Mod. 9Cr-1Mo steel is welded by SMAW with V-groove, and the effects of welding on tensile and impact properties are evaluated. The upper self energy of the weldment was only 57% of that of the base metal, and the DBTT T 41J and T 68J index temperatures of the weldment were higher than those of the base metal by 17 deg. C, 38 deg. C and 37 deg. C, respectively. (authors)

  18. Supernova equations of state including full nuclear ensemble with in-medium effects

    Science.gov (United States)

    Furusawa, Shun; Sumiyoshi, Kohsuke; Yamada, Shoichi; Suzuki, Hideyuki

    2017-01-01

    We construct new equations of state for baryons at sub-nuclear densities for the use in core-collapse supernova simulations. The abundance of various nuclei is obtained together with thermodynamic quantities. The formulation is an extension of the previous model, in which we adopted the relativistic mean field theory with the TM1 parameter set for nucleons, the quantum approach for d, t, h and α as well as the liquid drop model for the other nuclei under the nuclear statistical equilibrium. We reformulate the model of the light nuclei other than d, t, h and α based on the quasi-particle description. Furthermore, we modify the model so that the temperature dependences of surface and shell energies of heavy nuclei could be taken into account. The pasta phases for heavy nuclei and the Pauli- and self-energy shifts for d, t, h and α are taken into account in the same way as in the previous model. We find that nuclear composition is considerably affected by the modifications in this work, whereas thermodynamical quantities are not changed much. In particular, the washout of shell effect has a great impact on the mass distribution above T ∼ 1 MeV. This improvement may have an important effect on the rates of electron captures and coherent neutrino scatterings on nuclei in supernova cores.

  19. Self-energy renormalization for inhomogeneous nonequilibrium systems and field expansion via complete set of time-dependent wavefunctions

    Science.gov (United States)

    Kuwahara, Y.; Nakamura, Y.; Yamanaka, Y.

    2018-04-01

    The way to determine the renormalized energy of inhomogeneous systems of a quantum field under an external potential is established for both equilibrium and nonequilibrium scenarios based on thermo field dynamics. The key step is to find an extension of the on-shell concept valid in homogeneous case. In the nonequilibrium case, we expand the field operator by time-dependent wavefunctions that are solutions of the appropriately chosen differential equation, synchronizing with temporal change of thermal situation, and the quantum transport equation is derived from the renormalization procedure. Through numerical calculations of a triple-well model with a reservoir, we show that the number distribution and the time-dependent wavefunctions are relaxed consistently to the correct equilibrium forms at the long-term limit.

  20. The optimal entropy bound and the self-energy of test objects in the vicinity of a black hole

    OpenAIRE

    Mayo, Avraham E.

    1999-01-01

    Recently Bekenstein and Mayo conjectured an entropy bound for charged rotating objects. On the basis of the No-Hair principle for black holes, they speculate that this bound cannot be improved generically based on knowledge of other ``quantum numbers'', e.g. baryon number, which may be borne by the object. Here we take a first step in the proof of this conjecture. The proof make use of a gedanken experiment in which a massive object endowed with a scalar charge is lowered adiabatically toward...

  1. Mass-related inversion symmetry breaking and phonon self-energy renormalization in isotopically labeled AB-stacked bilayer graphene

    Czech Academy of Sciences Publication Activity Database

    Araujo, P. T.; Frank, Otakar; Mafra, D. L.; Fang, W.; Kong, J.; Dresselhaus, M. S.; Kalbáč, Martin

    2013-01-01

    Roč. 3, JUN 2013 (2013), s. 2061 ISSN 2045-2322 R&D Projects: GA MŠk LH13022; GA ČR(CZ) GAP208/12/1062 Institutional support: RVO:61388955 Keywords : WALLED CARBON NANOTUBES * RAMAN-SPECTROSCOPY * CHARGE-TRANSFER Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.078, year: 2013

  2. Fermi Surface of Sr_{2}RuO_{4}: Spin-Orbit and Anisotropic Coulomb Interaction Effects.

    Science.gov (United States)

    Zhang, Guoren; Gorelov, Evgeny; Sarvestani, Esmaeel; Pavarini, Eva

    2016-03-11

    The topology of the Fermi surface of Sr_{2}RuO_{4} is well described by local-density approximation calculations with spin-orbit interaction, but the relative size of its different sheets is not. By accounting for many-body effects via dynamical mean-field theory, we show that the standard isotropic Coulomb interaction alone worsens or does not correct this discrepancy. In order to reproduce experiments, it is essential to account for the Coulomb anisotropy. The latter is small but has strong effects; it competes with the Coulomb-enhanced spin-orbit coupling and the isotropic Coulomb term in determining the Fermi surface shape. Its effects are likely sizable in other correlated multiorbital systems. In addition, we find that the low-energy self-energy matrix-responsible for the reshaping of the Fermi surface-sizably differs from the static Hartree-Fock limit. Finally, we find a strong spin-orbital entanglement; this supports the view that the conventional description of Cooper pairs via factorized spin and orbital part might not apply to Sr_{2}RuO_{4}.

  3. Orbital order and effective mass enhancement in t2 g two-dimensional electron gases

    Science.gov (United States)

    Tolsma, John; Principi, Alessandro; Polini, Marco; MacDonald, Allan

    2015-03-01

    It is now possible to prepare d-electron two-dimensional electron gas systems that are confined near oxide heterojunctions and contain t2 g electrons with a density much smaller than one electron per metal atom. I will discuss a generic model that captures all qualitative features of electron-electron interaction physics in t2 g two-dimensional electron gas systems, and the use of a GW approximation to explore t2 g quasiparticle properties in this new context. t2 g electron gases contain a high density isotropic light mass xy component and low-density xz and yz anisotropic components with light and heavy masses in orthogonal directions. The high density light mass band screens interactions within the heavy bands. As a result the wave vector dependence of the self-energy is reduced and the effective mass is increased. When the density in the heavy bands is low, the difference in anisotropy between the two heavy bands favors orbital order. When orbital order does not occur, interactions still reshape the heavy-band Fermi surfaces. I will discuss these results in the context of recently reported magnetotransport experiments.

  4. Extended two-particle Green close-quote s functions and optical potentials for two particle scattering by by many-body targets

    International Nuclear Information System (INIS)

    Brand, J.; Cederbaum, L.S.

    1996-01-01

    An extension of the fermionic particle-particle propagator is presented that possesses similar algebraic properties to the single-particle Green close-quote s function. In particular, this extended two-particle Green close-quote s function satisfies Dyson close-quote s equation and its self energy has the same analytic structure as the self energy of the single-particle Green close-quote s function. For the case of a system interacting with one-particle potentials only, the two-particle self energy takes on a particularly simple form, just like the common self energy does. The new two-particle self energy also serves as a well behaved optical potential for the elastic scattering of a two-particle projectile by a many-body target. Due to its analytic structure, the two-particle self energy avoids divergences that appear with effective potentials derived by other means. Copyright copyright 1996 Academic Press, Inc

  5. Dynamical correlation effects in a weakly correlated material: Inelastic x-ray scattering and photoemission spectra of beryllium

    Science.gov (United States)

    Seidu, Azimatu; Marini, Andrea; Gatti, Matteo

    2018-03-01

    Beryllium is a weakly correlated simple metal. Still we find that dynamical correlation effects, beyond the independent-particle picture, are necessary to successfully interpret the electronic spectra measured by inelastic x-ray scattering (IXS) and photoemission spectroscopies (PES). By combining ab initio time-dependent density-functional theory (TDDFT) and many-body Green's function theory in the G W approximation (G W A ), we calculate the dynamic structure factor, the quasiparticle (QP) properties and PES spectra of bulk Be. We show that band-structure effects (i.e., due to interaction with the crystal potential) and QP lifetimes (LT) are both needed in order to explain the origin of the measured double-peak features in the IXS spectra. A quantitative agreement with experiment is obtained only when LT are supplemented to the adiabatic local-density approximation (ALDA) of TDDFT. Besides the valence band, PES spectra display a satellite, a signature of dynamical correlation due to the coupling of QPs and plasmons, which we are able to reproduce thanks to the combination of the G W A for the self-energy with the cumulant expansion of the Green's function.

  6. Resolution of an apparent inconsistency in the electromagnetic Casimir effect

    International Nuclear Information System (INIS)

    Alnes, H; Olaussen, K; Ravndal, F; Wehus, I K

    2007-01-01

    The vacuum expectation value of the electromagnetic energy-momentum tensor between two parallel plates in spacetime dimensions D > 4 is calculated in the axial gauge. While the pressure between the plates agrees with the global Casimir force, the energy density is divergent at the plates and not compatible with the total energy which follows from the force. However, subtracting the divergent self-energies of the plates, the resulting energy is finite and consistent with the force. In analogy with the corresponding scalar case for spacetime dimensions D > 2, the divergent self-energy of a single plate can be related to the lack of conformal invariance of the electromagnetic Lagrangian for dimensions D > 4. (fast track communication)

  7. Isotopic effects on phonon anharmonicity in layered van der Waals crystals: Isotopically pure hexagonal boron nitride

    Science.gov (United States)

    Cuscó, Ramon; Artús, Luis; Edgar, James H.; Liu, Song; Cassabois, Guillaume; Gil, Bernard

    2018-04-01

    Hexagonal boron nitride (h -BN) is a layered crystal that is attracting a great deal of attention as a promising material for nanophotonic applications. The strong optical anisotropy of this crystal is key to exploit polaritonic modes for manipulating light-matter interactions in 2D materials. h -BN has also great potential for solid-state neutron detection and neutron imaging devices, given the exceptionally high thermal neutron capture cross section of the boron-10 isotope. A good knowledge of phonons in layered crystals is essential for harnessing long-lived phonon-polariton modes for nanophotonic applications and may prove valuable for developing solid-state 10BN neutron detectors with improved device architectures and higher detection efficiencies. Although phonons in graphene and isoelectronic materials with a similar hexagonal layer structure have been studied, the effect of isotopic substitution on the phonons of such lamellar compounds has not been addressed yet. Here we present a Raman scattering study of the in-plane high-energy Raman active mode on isotopically enriched single-crystal h -BN. Phonon frequency and lifetime are measured in the 80-600-K temperature range for 10B-enriched, 11B-enriched, and natural composition high quality crystals. Their temperature dependence is explained in the light of perturbation theory calculations of the phonon self-energy. The effects of crystal anisotropy, isotopic disorder, and anharmonic phonon-decay channels are investigated in detail. The isotopic-induced changes in the phonon density of states are shown to enhance three-phonon anharmonic decay channels in 10B-enriched crystals, opening the possibility of isotope tuning of the anharmonic phonon decay processes.

  8. The effects of heavy doping on the electronic states in semiconductors

    International Nuclear Information System (INIS)

    Sernelius, B.E.

    1987-01-01

    The physics of semiconductors is reviewed. Topics included in the discussion are energy of the dopant system (kinetic energy in a many-valley semiconductor, exchange energy in an ellipsoidal Fermi volume, energy in a polar semiconductor), self energy shifts, band-gap narrowing, and piezo experiments. 31 refs., 27 figs

  9. Casimir-type effects for scalar fields interacting with material slabs

    International Nuclear Information System (INIS)

    Fialkovsky, I V; Pis'mak, Yu M; Markov, V N

    2010-01-01

    We study the field theoretical model of a scalar field in the presence of spacial inhomogeneities in the form of one and two finite-width mirrors (material slabs). The interaction of the scalar field with the defect is described with a position-dependent mass term. For a single-layer system we develop a rigorous calculation method and derive explicitly the propagator of the theory, the S-matrix elements and the Casimir self-energy of the slab. Detailed investigation of particular limits of self-energy is presented, and the connection to known cases is discussed. The calculation method is also found applicable to the two-mirror case. With its help we derive the corresponding Casimir energy and analyze it. For particular values of parameters of the model an obtained result recovers the Lifshitz formula. We also propose a procedure to unambiguously obtain the finite Casimir self-energy of a single slab without reference to any renormalization conditions. We hope that our approach can be applied to the calculation of Casimir self-energies in other demanded cases (such as a dielectric ball, etc).

  10. Non-Local Effects in Kaonic Atoms

    International Nuclear Information System (INIS)

    Lutz, M.; Florkowski, W.

    2000-01-01

    Optical potentials with non-local (gradient) terms are used to describe the spectra of kaonic atoms. The strength of the non-local terms is determined from a many-body calculation of the kaon self energy in nuclear matter. We find that the non-local terms are quantitatively important and the results depend strongly on the way the gradient terms are arranged. Phenomenologically successful description is obtained for p-wave like optical potentials. It is suggested that the microscopic form of the non-local interaction terms is obtained systematically by means of a semi-classical expansion of the nucleus structure. (author)

  11. Functional renormalization group study of fluctuation effects in fermionic superfluids

    Energy Technology Data Exchange (ETDEWEB)

    Eberlein, Andreas

    2013-03-22

    This thesis is concerned with ground state properties of two-dimensional fermionic superfluids. In such systems, fluctuation effects are particularly strong and lead for example to a renormalization of the order parameter and to infrared singularities. In the first part of this thesis, the fermionic two-particle vertex is analysed and the fermionic renormalization group is used to derive flow equations for a decomposition of the vertex in charge, magnetic and pairing channels. In the second part, the channel-decomposition scheme is applied to various model systems. In the superfluid state, the fermionic two-particle vertex develops rich and singular dependences on momentum and frequency. After simplifying its structure by exploiting symmetries, a parametrization of the vertex in terms of boson-exchange interactions in the particle-hole and particle-particle channels is formulated, which provides an efficient description of the singular momentum and frequency dependences. Based on this decomposition of the vertex, flow equations for the effective interactions are derived on one- and two-loop level, extending existing channel-decomposition schemes to (i) the description of symmetry breaking in the Cooper channel and (ii) the inclusion of those two-loop renormalization contributions to the vertex that are neglected in the Katanin scheme. In the second part, the superfluid ground state of various model systems is studied using the channel-decomposition scheme for the vertex and the flow equations. A reduced model with interactions in the pairing and forward scattering channels is solved exactly, yielding insights into the singularity structure of the vertex. For the attractive Hubbard model at weak coupling, the momentum and frequency dependence of the two-particle vertex and the frequency dependence of the self-energy are determined on one- and two-loop level. Results for the suppression of the superfluid gap by fluctuations are in good agreement with the literature

  12. High-Energy Anomaly in the Angle-Resolved Photoemission Spectra of Nd2-xCexCuO4: Evidence for a Matrix Element Effect

    Science.gov (United States)

    Rienks, E. D. L.; ńrrälä, M.; Lindroos, M.; Roth, F.; Tabis, W.; Yu, G.; Greven, M.; Fink, J.

    2014-09-01

    We use polarization-dependent angle-resolved photoemission spectroscopy (ARPES) to study the high-energy anomaly (HEA) in the dispersion of Nd2-xCexCuO4, x =0.123. We find that at particular photon energies the anomalous, waterfall-like dispersion gives way to a broad, continuous band. This suggests that the HEA is a matrix element effect: it arises due to a suppression of the intensity of the broadened quasiparticle band in a narrow momentum range. We confirm this interpretation experimentally, by showing that the HEA appears when the matrix element is suppressed deliberately by changing the light polarization. Calculations of the matrix element using atomic wave functions and simulation of the ARPES intensity with one-step model calculations provide further evidence for this scenario. The possibility to detect the full quasiparticle dispersion further allows us to extract the high-energy self-energy function near the center and at the edge of the Brillouin zone.

  13. High-energy anomaly in the angle-resolved photoemission spectra of Nd(2-x)Ce(x)CuO₄: evidence for a matrix element effect.

    Science.gov (United States)

    Rienks, E D L; Ärrälä, M; Lindroos, M; Roth, F; Tabis, W; Yu, G; Greven, M; Fink, J

    2014-09-26

    We use polarization-dependent angle-resolved photoemission spectroscopy (ARPES) to study the high-energy anomaly (HEA) in the dispersion of Nd(2-x)Ce(x)CuO₄, x=0.123. We find that at particular photon energies the anomalous, waterfall-like dispersion gives way to a broad, continuous band. This suggests that the HEA is a matrix element effect: it arises due to a suppression of the intensity of the broadened quasiparticle band in a narrow momentum range. We confirm this interpretation experimentally, by showing that the HEA appears when the matrix element is suppressed deliberately by changing the light polarization. Calculations of the matrix element using atomic wave functions and simulation of the ARPES intensity with one-step model calculations provide further evidence for this scenario. The possibility to detect the full quasiparticle dispersion further allows us to extract the high-energy self-energy function near the center and at the edge of the Brillouin zone.

  14. Correlation effects and spin-orbit interaction in Sr{sub 3}Ru{sub 2}O{sub 7}: LDA+DMFT study

    Energy Technology Data Exchange (ETDEWEB)

    Gorelov, Evgeny; Zhang, Guoren; Pavarini, Eva [IAS-3, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2013-07-01

    The layered ruthenates of the Ruddlesden-Popper family Sr{sub n+1}Ru{sub n}O{sub 3n+1} are interesting examples of strongly correlated transition metal compounds. Due to competing kinetic and Coulomb energies, that are of the same order for Ru 4d electrons, these compounds have very rich phase diagram, including Mott-insulator, ferro- and meta-magnetic phases. Among layered ruthenates the bilayered compound Sr{sub 3}Ru{sub 2}O{sub 7} is particularly interesting. It is known to be a paramagnetic metal close to ferro-magnetism and exhibits a metamagnetic behavior in external magnetic field. By using the LDA+DMFT (local-density approximation + dynamical mean-field theory) approach, we study magnetic properties and electron mass renormalization due to correlation effects. In our LDA+DMFT scheme we use maximally-localized Wannier orbitals obtained from Linearized Augmented Plane Wave (LAPW) calculations to build a low-energy Hubbard model for the Ru d bands; we use the weak-coupling CT-quantum Monte Carlo method to solve the quantum impurity problem. We take into account the full rotationally-invariant Coulomb interaction, as well as full on-site self-energy matrix in orbital space with spin-orbit coupling.

  15. Superconductivity in alkaline earth-substituted La2CuO/sub 4-y/

    International Nuclear Information System (INIS)

    Bednorz, J.G.; Mueller, K.A.; Takashige, M.

    1987-01-01

    La 2 CuO/sub 4-y/ ceramics containing a few percent of Ca 2+ , Sr 2+ , and Ba 2+ ions have been prepared. Resistivity and susceptibility measurements exhibit superconductive onsets (as in earlier Ba 2+ -containing samples). The onset temperature La 2 CuO/sub 4-y/ with Sr 2+ is higher and its superconductivity-induced diamagnetism larger than that found with Ba 2+ and Ca 2+ . This is proof that the electronic change resulting from alkaline earth-doping, rather than the size effect, is responsible for superconductivity. The ionic radius of Sr 2+ is close to that of La 3+ for which it presumably substitutes

  16. Side Effects

    Science.gov (United States)

    Side effects are problems that occur when cancer treatment affects healthy tissues or organs. Learn about side effects caused by cancer treatment. Know what signs and symptoms to call your doctor about. Learn about treatments for side effects.

  17. QED effects in the pseudoscalar meson sector

    Energy Technology Data Exchange (ETDEWEB)

    Horsley, R. [School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD (United Kingdom); Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo, 650-0047 (Japan); Perlt, H. [Institut für Theoretische Physik, Universität Leipzig, Brüderstrasse 16, Leipzig, 04109 (Germany); Pleiter, D. [Jülich Supercomputer Centre, Forschungszentrum Jülich, Jülich, 52425 (Germany); Institut für Theoretische Physik, Universität Regensburg, Regensburg, 93040 (Germany); Rakow, P.E.L. [Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, Peach Street , Liverpool, L69 3BX (United Kingdom); Schierholz, G. [Deutsches Elektronen-Synchrotron DESY, Hamburg, 22603 (Germany); Schiller, A. [Institut für Theoretische Physik, Universität Leipzig, Brüderstrasse 16, Leipzig, 04109 (Germany); Stokes, R. [CSSM, Department of Physics, University of Adelaide, Adelaide, SA, 5005 (Australia); Stüben, H. [Regionales Rechenzentrum, Universität Hamburg, Hamburg, 20146 (Germany); Young, R.D.; Zanotti, J.M. [CSSM, Department of Physics, University of Adelaide, Adelaide, SA, 5005 (Australia); Collaboration: the QCDSF and UKQCD collaboration

    2016-04-15

    In this paper we present results on the pseudoscalar meson masses from a fully dynamical simulation of QCD+QED, concentrating particularly on violations of isospin symmetry. We calculate the π{sup +}–π{sup 0} splitting and also look at other isospin violating mass differences. We have presented results for these isospin splittings in http://arxiv.org/abs/1508.06401. In this paper we give more details of the techniques employed, discussing in particular the question of how much of the symmetry violation is due to QCD, arising from the different masses of the u and d quarks, and how much is due to QED, arising from the different charges of the quarks. This decomposition is not unique, it depends on the renormalisation scheme and scale. We suggest a renormalisation scheme in which Dashen’s theorem for neutral mesons holds, so that the electromagnetic self-energies of the neutral mesons are zero, and discuss how the self-energies change when we transform to a scheme such as (MS)-bar , in which Dashen’s theorem for neutral mesons is violated.

  18. Exchange and polarization effects in the elementary excitation spectrum of a hydrogen atom immersed in a hot plasma

    International Nuclear Information System (INIS)

    Dharma-wardana, M.W.C.; Grimaldi, F.; Lecourt, A.; Pellissier, J.

    1980-01-01

    The one-particle hydrogenic Green's function has been calculated for a partially ionized plasma consisting of hydrogen atoms, electrons, and protons at high temperatures. The theoretical method extends a previous publication and involves an evaluation of the mass operator in the Dyson equation to include proper self-energy parts to ''all orders'' in the screened interaction. This mass operator characterizes the effective micropotential felt by the atom in the plasma and determines all of the one-particle properties and some two-particle properties associated with the atomic subsystem. The first-order mass operator is nonzero only for exchange scattering, which leads to a frequency-independent exchange shift. This temperature- and density-dependent theory of the exchange shift replaces the usual semiphenomenological schemes based on the Slater-Kohn-Sham type of theory. The exchange-shifted Green's functions are used in evaluating the higher-order contributions. Computer calculations and the resolution of the poles of the Green's function lead to level shifts, widths, and spectral functions. These are calculated within both the second-order and the all-order theory. The second-order theory, which may be valid at sufficiently high densities and in turbulent plasmas, overemphasises the atom-plasmon coupling and shows new structures. The inclusion of contributions beyond second order removes these structures and produces a more ''conventional'' spectral-intensity function. The effects of center-of-mass motion on the level shifts and level profiles are investigated and the onset of plasma instabilities touched upon. These calculations make contact with the work on ''plasma-polarization shifts'' and provide an approach to q,ω-dependent plasma microfields

  19. Many-body effect in the partial singles N2,3 photoelectron spectroscopy spectrum of atomic Cd

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2008-01-01

    We can extract out the photoelectron kinetic energy (KE) dependent imaginary part of the core-hole self-energy by employing Auger-photoelectron coincidence spectroscopy (APECS). The variation with photoelectron KE in the Auger electron spectroscopy (AES) spectral peak intensity of a selected decay channel measured in coincidence with photoelectrons of a selected KE is the partial singles (non-coincidence) photoelectron spectroscopy (PES) spectrum, i.e., the product of the singles PES one and the branching ratio of the partial Auger decay width of a selected decay channel to the imaginary part of the core-hole self-energy. When a decay channel the partial Auger decay width of which is photoelectron KE independent is selected, we can extract out spectroscopically the imaginary part of the core-hole self-energy because the variation with photoelectron KE in the relative spectral intensity of the partial singles PES spectrum to the singles one is that in the branching ratio of the partial Auger decay width of a selected decay channel. As an example we discussed the N 2,3 -hole self-energy of atomic Cd

  20. Placebo Effect

    Science.gov (United States)

    ... C. Spencer, MD Steven Karceski, MD The placebo effect Joseph H. Friedman, MD Richard Dubinsky, MD WHAT ... placebo: a “dummy” medication that should have no effect on the condition. Placebos are not only drugs. ...

  1. A note on “Electron self-energy in logarithmic electrodynamics” by P. Gaete and J. Helayël-Neto

    International Nuclear Information System (INIS)

    Gitman, Dmitry M.; Shabad, Anatoly E.

    2014-01-01

    We propose an identification of the free parameter in the model of nonlinear electrodynamics proposed in Gaete and Helayël-Neto (Eur Phys J C 74:2816, 2014) by equating the second term in the power expansion of its Lagrangian with that in the expansion of the Heiseberg–Euler Lagrangian. The resulting value of the field-energy of a point-like charge makes 0.988 of the electron mass, if the charge is that of the electron

  2. A note on “Electron self-energy in logarithmic electrodynamics” by P. Gaete and J. Helayël-Neto

    Energy Technology Data Exchange (ETDEWEB)

    Gitman, Dmitry M., E-mail: gitman@dfn.if.usp.br [Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, CEP 05508-090, São Paulo, SP (Brazil); P. N. Lebedev Physics Institute, Leninsky Prospekt 53, 117924, Moscow (Russian Federation); P. Tomsk State University, Lenin Prospekt 36, 634050, Tomsk (Russian Federation); Shabad, Anatoly E., E-mail: anshabad@yahoo.com [P. N. Lebedev Physics Institute, Leninsky Prospekt 53, 117924, Moscow (Russian Federation); P. Tomsk State University, Lenin Prospekt 36, 634050, Tomsk (Russian Federation)

    2014-11-28

    We propose an identification of the free parameter in the model of nonlinear electrodynamics proposed in Gaete and Helayël-Neto (Eur Phys J C 74:2816, 2014) by equating the second term in the power expansion of its Lagrangian with that in the expansion of the Heiseberg–Euler Lagrangian. The resulting value of the field-energy of a point-like charge makes 0.988 of the electron mass, if the charge is that of the electron.

  3. Dynamical electron-phonon coupling, G W self-consistency, and vertex effect on the electronic band gap of ice and liquid water

    Science.gov (United States)

    Ziaei, Vafa; Bredow, Thomas

    2017-06-01

    We study the impact of dynamical electron-phonon (el-ph) effects on the electronic band gap of ice and liquid water by accounting for frequency-dependent Fan contributions in the el-ph mediated self-energy within the many-body perturbation theory (MBPT). We find that the dynamical el-ph coupling effects greatly reduce the static el-ph band-gap correction of the hydrogen-rich molecular ice crystal from-2.46 to -0.23 eV in great contrast to the result of Monserrat et al. [Phys. Rev. B 92, 140302 (2015), 10.1103/PhysRevB.92.140302]. This is of particular importance as otherwise the static el-ph gap correction would considerably reduce the electronic band gap, leading to considerable underestimation of the intense peaks of optical absorption spectra of ice which would be in great disagreement to experimental references. By contrast, the static el-ph gap correction of liquid water is very moderate (-0.32 eV), and inclusion of dynamical effects slightly reduces the gap correction to -0.19 eV. Further, we determine the diverse sensitivity of ice and liquid water to the G W self-consistency and show that the energy-only self-consistent approach (GnWn ) exhibits large implicit vertex character in comparison to the quasiparticle self-consistent approach, for which an explicit calculation of vertex corrections is necessary for good agreement with experiment.

  4. Systems effectiveness

    CERN Document Server

    Habayeb, A R

    1987-01-01

    Highlights three principal applications of system effectiveness: hardware system evaluation, organizational development and evaluation, and conflict analysis. The text emphasizes the commonality of the system effectiveness discipline. The first part of the work presents a framework for system effectiveness, partitioning and hierarchy of hardware systems. The second part covers the structure, hierarchy, states, functions and activities of organizations. Contains an extended Appendix on mathematical concepts and also several project suggestions.

  5. "Further Effects"

    Science.gov (United States)

    Kinigstein, Steven Michael

    In writing Further Effects, I intended to illustrate the benefits that are to be had from the use of effects - processing, when applied at the compositional level, rather than as a post-compositional afterthought. When effects are used creatively in the compositional stage, they will influence the very nature of a piece. They are capable of expressing rhythmic and metric ideas. They can alter the natural timbre of an instrument. This can be done on levels of abstraction ranging from discreet subtlety to disguise beyond recognition. There is one effect (known as "pitch shift.") that allows an instrument to play pitches that are well outside of its range. In Further Effects, I direct the performers to use a volume pedal (which I view as a tool, rather than an effect) for the broadened creative use of dynamics that it so efficiently grants. The use of an effects processor and volume pedal creates a need for ancillary equipment. An amplifier, cables, and an electric hook-up (a microphone or a pickup) will be required for each instrument. While an amplifier serves to project the processed sound, there must also be a device or method to suppress unprocessed sound. A great deal of thought and work goes into the use of effects; yet I feel it is wasteful to use this musical resource merely as post-compositional decoration.

  6. Conserving GW scheme for nonequilibrium quantum transport in molecular contacts

    DEFF Research Database (Denmark)

    Thygesen, Kristian Sommer; Rubio, Angel

    2008-01-01

    We give a detailed presentation of our recent scheme to include correlation effects in molecular transport calculations using the nonequilibrium Keldysh formalism. The scheme is general and can be used with any quasiparticle self-energy, but for practical reasons, we mainly specialize to the so......-called GW self-energy, widely used to describe the quasiparticle band structures and spectroscopic properties of extended and low-dimensional systems. We restrict the GW self-energy to a finite, central region containing the molecule, and we describe the leads by density functional theory (DFT). A minimal...

  7. Greenhouse effect

    International Nuclear Information System (INIS)

    1992-01-01

    This special issue is devoted to the greenhouse effect and reviews the possible climate change by mankind, paleoclimates, climate models, measurement of terrestrial temperature, CO 2 concentration and energy policy

  8. Biological effects

    International Nuclear Information System (INIS)

    Trott, K.R.

    1973-01-01

    Following an introduction into the field of cellular radiation effect considering the most important experimental results, the biological significance of the colony formation ability is brought out. The inactivation concept of stem cells does not only prove to be good, according to the present results, in the interpretation of the pathogenesis of acute radiation effects on moult tissue, it also enables chronicle radiation injuries to be interpreted through changes in the fibrous part of the organs. Radiation therapy of tumours can also be explained to a large extent by the radiation effect on the unlimited reproductiveness of tumour cells. The more or less similar dose effect curves for healthy and tumour tissue in practice lead to intermittent irradiation. The dependence of the intermittent doses and intervals on factors such as Elkind recovery, synchronisation, redistribution, reoxygenation, repopulation and regeneration are reviewed. (ORU/LH) [de

  9. Effective Programming

    DEFF Research Database (Denmark)

    Frost, Jacob

    To investigate the use of VTLoE as a basis for formal derivation of functional programs with effects. As a part of the process, a number of issues central to effective formal programming are considered. In particular it is considered how to develop a proof system suitable for pratical reasoning......, how to implement this system in the generic proof assistant Isabelle and finally how to apply the logic and the implementation to programming....

  10. Facebook Effect

    OpenAIRE

    STOICA, Anamaria

    2011-01-01

    This research paper is intended to understand the effects that Facebook, the social networking site has upon us, whether it influences our lives in a good or in a bad way. In order to understand the Facebook Effect we are trying to see how it impacts our lives at economic level,social level, political level, terminology level , psychological level and cultural level . Starting from the question : What does Facebook want? we found several answers consisting in pros and cons of this phenomenon ...

  11. Effective leadership

    OpenAIRE

    Vávrová, Zuzana

    2010-01-01

    In my bachelor thesis I describe problems of effective leadership in organization in relation with organization's objectives filling. I focus here on main principles of leadership process. I characterize process of leadership and personality of leader, who is active executor of this process in organization. The effective leadership is here evaluated mainly from organization theory point of view and in relation with requirements to management, especially its relation with leadership and its de...

  12. Effects of disorder on the electron pairing

    International Nuclear Information System (INIS)

    Oviedo-Roa, R.; Wang, C.; Navarro, O.

    1996-01-01

    The electron pairing in randomly disordered lattices is studied by using an attractive Hubbard model, and by mapping the many-body problem onto a tight-binding one in a higher dimensional space, where a diagonal disorder is considered within the coherent-potential approximation. The results show an enhancement of the pair-binding energy as the self-energy difference increases in a binary alloy A x B 1-x . This fact suggests that the pairing process is highly sensitive to the one-particle localization condition. A ground-state phase diagram for on-site interaction disorder shows regions where pairing is avoided for ordered diatomic systems but not for disordered case

  13. Non-local effects in kaonic atoms

    International Nuclear Information System (INIS)

    Lutz, M.; Florkowski, W.

    2000-04-01

    Optical potentials with non-local (gradient) terms are used to describe the spectra of kaonic atoms. The strength of the non-local terms is determined from a many-body calculation of the kaon self-energy in nuclear matter. The optical potentials show strong non-linearities in the nucleon density and sizeable non-local terms. We find that the non-local terms are quantitatively important and the results depend strongly on the way the gradient terms are arranged. Phenomenologically successful fits are obtained for p-wave like optical potentials. It is suggested that the microscopic form of the non-local interaction terms is obtained systematically by means of a semi-classical expansion of the nucleus structure. We conclude that a microscopic description of kaonic atom data requires further detailed studies of the microscopic K - nuclear dynamics. (orig.)

  14. [Effective delegation].

    Science.gov (United States)

    Fang, Li; Hung, Chich-Hsiu

    2008-12-01

    Ninety-seven percent of middle level managers feel they face work overload. The source of this problem may lie in a failure to delegate tasks effectively. If a manager does not effectively delegate, he/she is more likely to report fatigue, stress and depression. Conversely, effectively delegating tasks will improve overall job quality, professional growth in subordinates and cooperation within the team. While it is necessary for managers to delegate tasks effectively, few can be considered to be good natural 'delegators'. Learning and training is necessary for managers to develop the necessary confidence and maturity. This article describes the definitions, purpose and benefits of delegation; factors related to effective delegation; strategies related to successful delegation and skills related to performing cross-cultural delegations. Such issues have seldom been addressed in previous articles. Moreover, nursing implications and suggested applications in nursing practice, education, management and research are mentioned. This article is intended to provide directions to nursing managers and subordinates to promote delegation knowledge and skills.

  15. Treatment Effects

    DEFF Research Database (Denmark)

    Heckman, James J.; Lopes, Hedibert F.; Piatek, Rémi

    2014-01-01

    This paper contributes to the emerging Bayesian literature on treatment effects. It derives treatment parameters in the framework of a potential outcomes model with a treatment choice equation, where the correlation between the unobservable components of the model is driven by a low-dimensional v......This paper contributes to the emerging Bayesian literature on treatment effects. It derives treatment parameters in the framework of a potential outcomes model with a treatment choice equation, where the correlation between the unobservable components of the model is driven by a low...... to observe the same person in both the treated and untreated states, but it also turns out to be straightforward to implement. Formulae are provided to compute mean treatment effects as well as their distributional versions. A Monte Carlo simulation study is carried out to illustrate how the methodology can...

  16. Genetic effects

    International Nuclear Information System (INIS)

    Kato, Hiroo

    1975-01-01

    In 1948-1953 a large scale field survey was conducted to investigate the possible genetic effects of A-bomb radiation on over 70,000 pregnancy terminations in the cities of Hiroshima and Nagasaki. The indices of possible genetic effect including sex ratio, birth weight, frequency of malformation, stillbirth, neonatal death, deaths within 9 months and anthropometric measurements at 9 months of age for these children were investigated in relation to their parent's exposure status to the A-bomb. There were no detectable genetic effects in this sample, except for a slight change in sex ratio which was in the direction to be expected if exposure had induced sex-linked lethal mutations. However, continued study of the sex ratio, based upon birth certificates in Hiroshima and Nagasaki for 1954-1962, did not confirm the earlier trend. Mortality in these children of A-bomb survivors is being followed using a cohort of 54,000 subjects. No clearly significant effect of parental exposure on survival of the children has been demonstrated up to 1972 (age 17 on the average). On the basis of the regression data, the minimal genetic doubling dose of this type of radiation for mutations resulting in death is estimated at 46 rem for the father and 125 rem for the mother. (auth.)

  17. Ventilation Effectiveness

    DEFF Research Database (Denmark)

    Mundt, M.; Mathisen, H. M.; Moser, M.

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-un...

  18. Listening Effectively.

    Science.gov (United States)

    Freshour, Frank W.

    1987-01-01

    Research indicates that people spend roughly 45 to 65 percent of their waking moments listening to other persons. To help administrators improve their listening effectiveness, a format to develop a profile of personal listening styles is provided. The strengths and weaknesses of six different listening styles are explored along with ways to…

  19. Effective Consumerism.

    Science.gov (United States)

    Daugherty, Mabel

    This module, consisting of materials for use in conducting a consumer education mini-course, deals with effective consumerism. Covered in the individual lessons are the following topics: being prepared with information (sources of consumer information and subscription forms); evaluating warranties and service contracts; evaluating advertising and…

  20. Health effects

    Energy Technology Data Exchange (ETDEWEB)

    Mahieu, L

    1998-07-01

    The main objectives of research in the field of health effects at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study; (4) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phases of its development; (5) to assess the genetic risks of material exposure to ionizing radiation; (6) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (7) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas for 1997 are reported.

  1. Health effects

    International Nuclear Information System (INIS)

    Mahieu, L.

    1998-01-01

    The main objectives of research in the field of health effects at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study; (4) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phases of its development; (5) to assess the genetic risks of material exposure to ionizing radiation; (6) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (7) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas for 1997 are reported

  2. Effective interactions

    International Nuclear Information System (INIS)

    Elliott, J.P.

    1981-01-01

    This chapter attempts to describe and compare some of the more important nucleon-nucleon interactions that have been used in nuclear structure calculations, and to relate them where possible to the real nucleon-nucleon interaction. Explains that different interactions have been used depending on whether one is fitting to total binding energies and densities with a Hartree Fock (HF) calculation or fitting to spectra and spectroscopic data in a shell model calculation. Examines both types of calculation after two preliminary sections concerned with notation and with the philosophy underlying the use of model spaces and effective interactions. Discusses Skyrme interactions, finite range interactions, small model space, large model space, and the Sussex potential matrix elements. Focuses on the more empirical approaches in which a simple form is chosen for the effective interaction in a given model space and the parameters are deduced from fitting many-body data

  3. Ventilation effectiveness

    CERN Document Server

    Mathisen, Hans Martin; Nielsen, Peter V; Moser, Alfred

    2004-01-01

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-understand descriptions of the indices used to mesure the performance of a ventilation system and which indices to use in different cases.

  4. Greenhouse effect

    International Nuclear Information System (INIS)

    Lepetit, J.P.

    1992-01-01

    This book speaks about the growth of greenhouse gases content in the atmosphere and try to forecast the different scenarios which may happen. But, in spite of international cooperation and coordinated research programs, nobody owns the answer. So possible future climatic changes depend on the behavior of the concerned actors. A review of energy policy driven by USA, Japan, Sweden, United Kingdom and Federal Republic of Germany is given. Political management of this file and public opinion in front of greenhouse effect are also described. 7 refs., 3 figs., 6 tabs

  5. Effective Teachers

    Directory of Open Access Journals (Sweden)

    Beverly A. King Miller

    2015-09-01

    Full Text Available This article focuses on the educational strategies that can be used to support female students of African descent in their persistence in science, technology, engineering, and mathematics (STEM education and careers. STEM careers have historically been White male and White female dominated, which has yielded an underrepresentation of those of African descent. Drawing from a grounded qualitative case study, the data used for this article share the responses of Afro-Caribbean females in STEM who have immigrated to the United States from the country of Panama. As Latinas, they are representative of the changing face in the American educational system—bilingual, multicultural, and of African descent. The strategies offered reflect their own teaching practices, their former teachers, or experiences with their children’s teachers. What emerged were descriptions of four strategies and behaviors of effective teachers that align with Ladson-Billings’s culturally relevant pedagogy and Gay’s culturally responsive teaching. Included in the findings are the high standards and expectations embodied by effective teachers that serve to positively inspire their students. Culturally responsive teachers create an atmosphere of learning that supports academic success, conveying their belief in their students’ ability based upon their own reflectivity. As the U.S. educational system continues to become multilingual and multicultural, there is need for strategies for the successful inclusion and progression of students in STEM educational pathways and careers. This will occur as teachers challenge themselves to be the agents of change in the lives of their students.

  6. Radiation effects

    International Nuclear Information System (INIS)

    Collings, E.W.

    1986-01-01

    An important cause of deterioration in superconducting magnets intended for high-energy physics and fusion-reactor applications is radiation damage. The present chapter deals chiefly with the effects of electron, proton, gamma and neutron irradiation on the properties of stabilized Ti-Nb-base composite superconductors. The authors examine the particle-accelerator environment, electron irradiation of Ti-Nb superconductor, proton irradiation of Ti-Nb superconductor and its stabilizer, and deuteron irradiation of Ti-Nb superconductor. A section discussing the fusion reactor environment in general is presented, and the two principal classes of fusion reactor based on the magnetic-confinement concept, namely the tokamak and the mirrormachine are examined. Also discussed is neutron irradiation of Cu/TiNb composite superconductors and critical current density of neutronirradiated Ti-Nb. Finally, radiation damage to stabilizer and insulating materials is described

  7. Health effects

    International Nuclear Information System (INIS)

    Mahieu, L.

    1998-01-01

    The objectives of the research in the field of epidemiology , performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study. For radiobiology, the main objectives are: (1) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phase of its development, (2) to assess the genetic risks of maternal exposure to ionizing radiation, (3) to elucidate the mechanisms by which damage to the brain and mental retardation are caused in man after prenatal irradiation. The main achievements in these domains for 1997 are presented

  8. Condom effectiveness.

    Science.gov (United States)

    Porche, D J

    1998-01-01

    People who choose not to abstain from sexual intercourse can use barrier contraceptive methods, such as condoms, to reduce their risk of contracting HIV and other sexually transmitted diseases (STDs). Health care providers who provide safer sex education and counseling should provide information on condoms as a way of reducing the risk of HIV/STD transmission. Since latex condoms are regulated by the US Food and Drug Administration (FDA) as medical devices, FDA regulations govern latex condom manufacturing and testing in accordance with stringent national standards. The FDA randomly tests imported condoms according to the same stringent quality control standards as US-produced condoms. Condom effectiveness, however, depends upon their correct and consistent use during every sexual act. Relevant data and guidelines are presented on the correct use of male latex and female polyurethane condoms. Both male latex and female polyurethane condoms can prevent the transmission of HIV and other STDs.

  9. Doping effect on the physical properties of Ca10Pt3As8(Fe2As2)5 single crystals

    Science.gov (United States)

    Pan, Jiayun; Karki, Amar; Plummer, E. W.; Jin, Rongying

    2017-12-01

    Ca10Pt3As8(Fe2As2)5 is a unique parent compound for superconductivity, which consists of both semiconducting Pt3As8 and metallic FeAs layers. We report the observation of superconductivity induced via chemical doping in either Ca site using rare-earth (RE) elements (RE  =  La, Gd) or Fe site using Pt. The interlayer distance and the normal-state physical properties of the doped system change correspondingly. The coupled changes include (1) superconducting transition temperature T c increases with increasing both doping concentration and interlayer distance, (2) our T c value is higher than previously reported maximum value for Pt doping in the Fe site, (3) both the normal-state in-plane resistivity and out-of-plane resistivity change from non-metallic to metallic behavior with increasing doping concentration and T c, and (4) the transverse in-plane magnetoresistance (MRab) changes from linear-field dependence to quadratic behavior upon increasing T c. For La-doped compound with the highest T c (~35 K), upper critical fields (Hc2ab , Hc2c ), coherence lengths (ξ ab, ξ c), and in-plane penetration depth (λ ab) are estimated. We discuss the relationship between chemical doping, interlayer distance, and physical properties in this system.

  10. Radiological effects

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Environmental monitoring in the vicinity of the Calvert Cliffs Nuclear Power Plant has been shown the radiation dose to the public from plant operation to be quite small. Calculations from the reported release rates yield 0.2 mrem whole body dose and 0.6 mrem skin dose for the calendar quarter of maximum release. Radioactivity discharges to the Chesapeake Bay have resulted in detectable concentrations of /sup 110m/Ag, 58 Co, and 60 Co in sediments and shellfish. The area yielding samples with detectable concentrations of plant effluents extends for roughly six miles up and down the western shore, with maximum values found at the plant discharge area. The radiation dose to an individual eating 29 doz oysters and 15 doz crabs (5 kg of each) taken from the plant discharge area would be about 4/1000 mrem whole body dose and 0.2 mrem gastrointestinal tract dose (about 0.007% and 0.5% of the applicable guidelines, respectively.) Comparison of these power plant-induced doses with the fluctuations in natural radiation dose already experienced by the public indicates that the power plant effects are insignificant. The natural variations are tens of times greater than the maximum doses resulting from Calvert Cliffs Power Plant. Although operations to date provide an insufficient basis to predict radiological impact of the Calvert Cliffs Plant over its operational lifetime, available data indicate that the plant should continue to operate with insignificant radiological impact, well within all applicable guidelines

  11. Thyroid effects

    International Nuclear Information System (INIS)

    Maxon, H.; Thomas, S.; Buncher, C.; Book, S.; Hertzberg, V.

    1985-01-01

    Risk coefficients for thyroid disorders have been developed for both 131 I and external x or gamma low-LET radiation. A linear, no-threshold model has been used for thyroid neoplasms. A linear, threshold model has been used for other thyroid disorders. Improvements since the Reactor Safety Study were made possible by relevant new animal and human data. Major changes are as follows. Animal data are used to supplement the human experience where necessary. A specific risk estimate model is used for thyroid neoplasms, which accounts for observed effects of gender and age at exposure on risk. For thyroid cancer, the basis of the risk coefficients is the experience of North Americans following x-irradiation for benign disease in childhood. This recognizes possible differences in susceptibility in people of different heritage. A minimum induction period for thyroid neoplasms following irradiation is used to define periods at risk. An upper bound risk coefficient for cancer induction following exposure to 131 I is based on human experience at relatively low dose exposures. While the overall lifetime risks of death due to thyroid cancer are consistent with projections by the ICRP, BEIR III, and UNSCEAR Reports, the current model permits greater flexibility in determining risk for population subgroups. 88 references, 8 tables

  12. A pseudogap model beyond BCS for the cuprates: The effect of order parameter symmetry, Debye frequency and band structure

    International Nuclear Information System (INIS)

    Rodriguez-Nunez, J.J.; Schmidt, A.A.; Beck, H.; Valera, M.

    2005-08-01

    One of the most intriguing aspects of high temperature superconductors (HTSC) is the presence of the pseudogap in the normal and the superconducting phases of the cuprate compounds. Several pseudogap models have been proposed to explain the $abnormal$ properties of the cuprates. One of the recent models relies on the assumption that the self-energy is given by Σ PG (iω n )=- E g 2 (k)G 0 (k,-iω n ) where G 0 (k,iω n is the one- particle free Green function. Going beyond this mean field model for the pseudogap we now take into account fluctuations of the pseudogap as Σ PG (iω n )=- E g 2 (k)G PG (k,-iω n ) where G PG (k,iω n is the one-particle full Green function. We study the combined effect of the band structure and the Debye frequency, ω D , on the superconducting critical temperature, T c , as a function of the number of carriers per site, n. Our conclusions are: 1) increasing the value of V/t increases the value of T c /t; 2) increasing the value of E G /t decreases the value of T c /t. By the way, one needs some critical value of V/t to have finite values of T c /t. This is the reason we have taken high values of V/ to find superconductivity; 3) decreasing the value of ω D /t decreases the value of T c /t. This is reasonable since we have less available states around the Fermi; 4) the inclusion of α', which we call the effect of the band structure, is important because it moves the center of curve of T c /t x n. The center of this curve, with respect to half-filling (n=1), is displaced to the left if α'>0.0; 5) the chemical potential is defined in the region where T c /t ≠ 0. However, in this region, it is almost identical for different values of V/t. This is due to the fact that μ is a global property; 6) our model always produces d-wave superconductivity around the Fermi level, independent whether E G (K-bar)/t is s- or d-wave symmetry. (author)

  13. Effects of Anesthesia

    Science.gov (United States)

    ... About Policymakers Media ASA Member Toolkit Anesthesia 101 Effects of Anesthesia Explore this page: Effects of Anesthesia ... the types of anesthesia and their side effects? Effects of Anesthesia If you’re having surgery, you ...

  14. Effect of soft mode on shear viscosity of quark matter

    International Nuclear Information System (INIS)

    Fukutome, Takahiko; Iwasaki, Masaharu

    2008-01-01

    We calculate the shear viscosity of quark matter at finite temperature and density. If we assume that the quark interacts with the soft mode, which is a collective mode of a quark-antiquark pair, the self-energy of the quark is calculated by quasi-particle random phase approximation. It is shown that its imaginary part is large and its mean free path is short. With the use of the Kubo formula, the shear viscosity of quark matter decreases. The Reynolds number of quark matter is estimated to be about 10. As temperature increases, shear viscosity increases gradually for T>200 MeV. Moreover it is shown that the shear viscosity also increases with the chemical potential for μ>200 MeV. (author)

  15. Colossal magnetodielectric effect caused by magnetoelectric effect ...

    Indian Academy of Sciences (India)

    The colossal magnetodielectric effect is reported in Pb(Zr,Ti)O3/Terfenol-D laminate composite under low magnetic field. When the composite is placed in an external a.c. magnetic field, magnetoelectric effect is produced, as a result, the dielectric properties of the Pb(Zr,Ti)O3 is changed, i.e. magnetodielectric effect. Both the ...

  16. Military Effectiveness: A Reappraisal

    National Research Council Canada - National Science Library

    Bernasconi, Jeffrey J

    2007-01-01

    .... Two divergent theories cover the ground of military effectiveness. One looks at the interaction of social structures, whereas the other looks at the effect organization has on military effectiveness...

  17. Network-Based Effectiveness

    National Research Council Canada - National Science Library

    Friman, Henrik

    2006-01-01

    ...) to increase competitive advantage, innovation, and mission effectiveness. Network-based effectiveness occurs due to the influence of various factors such as people, procedures, technology, and organizations...

  18. Colossal magnetodielectric effect caused by magnetoelectric effect ...

    Indian Academy of Sciences (India)

    -D laminate composite under low magnetic field. When the composite is placed in an external a.c. magnetic field, magnetoelectric effect is produced, as a result, the dielectric properties of the Pb(Zr,Ti)O3 is changed, i.e. magnetodielectric effect ...

  19. Biological effects of radiation

    International Nuclear Information System (INIS)

    2013-01-01

    This fourth chapter presents: cell structure and metabolism; radiation interaction with biological tissues; steps of the production of biological effect of radiation; radiosensitivity of tissues; classification of biological effects; reversibility, transmissivity and influence factors; pre-natal biological effects; biological effects in therapy and syndrome of acute irradiation

  20. Casualties and threshold effects

    International Nuclear Information System (INIS)

    Mays, C.W.; National Cancer Inst., Bethesda

    1988-01-01

    Radiation effects like cancer are denoted as casualties. Other radiation effects occur almost in everyone when the radiation dose is sufficiently high. One then speaks of radiation effects with a threshold dose. In this article the author puts his doubt about this classification of radiation effects. He argues that some effects of exposure to radiation do not fit in this classification. (H.W.). 19 refs.; 2 figs.; 1 tab

  1. Hydrogen-induced delayed cracking: 1. Strain energy effects on hydrogen solubility

    International Nuclear Information System (INIS)

    Puls, M.P.

    1978-08-01

    Based on Li, Oriani and Darken's derivation of the chemical potential of a solute in a stressed solid and Eshelby's method for obtaining the strain energy of solids containing coherent inhomogeneous inclusions, we have carried out a detailed theoretical analysis of the factors governing hydrogen solubility in stressed and unstressed zirconium and its alloys. Specifically, the analysis demonstrates the strong influence hydride self-stresses may have on the terminal solid solubility of hydrogen in zirconium. The self-energy arises due to the misfit strains between matrix and precipitate. We have calculated the total molal self-strain energy of some commonly observed δ and γ-hydride shapes and orientations. The magnitude of this energy is substantial. Thus for γ-hydride plates lying on basal planes, it is 4912 J/mol, while for γ-hydride needles with the needle axis parallel to the directions of the α-zirconium matrix, it is 2662 J/mol. This self-strain energy causes a shift in the terminal solid solubility. For example, at 77 o C, assuming fully constrained basal plane δ-hydride plates, the terminal solid solubility is increased 5.4 times over the stress-free case. We have also calculated the effect of external stress on the terminal solid solubility. This is governed by the interaction energy arising from the interaction of the applied stresses with the precipitate's misfit strain components. The interaction energy has been calculated for δ and γ-hydride plates and needles, taking full account of the anisotropy of the misfit. The interaction energy is negative for tensile applied stresses and, as a result of the anisotropic misfit, is texture-dependent. Its magnitude is small for most applied stresses but can achieve values of the order of the self-strain energy in the plastic zone of a plane-strain crack. We have also carried out a careful analysis of the solubility data of Kearns and Erickson and Hardie. This analysis is based partly on the theoretical

  2. DAFX Digital Audio Effects

    CERN Document Server

    2011-01-01

    The rapid development in various fields of Digital Audio Effects, or DAFX, has led to new algorithms and this second edition of the popular book, DAFX: Digital Audio Effects has been updated throughout to reflect progress in the field. It maintains a unique approach to DAFX with a lecture-style introduction into the basics of effect processing. Each effect description begins with the presentation of the physical and acoustical phenomena, an explanation of the signal processing techniques to achieve the effect, followed by a discussion of musical applications and the control of effect parameter

  3. Experiences with effects specifications

    DEFF Research Database (Denmark)

    Simonsen, Jesper; Hertzum, Morten; Barlach, Anders

    2011-01-01

    We describe the effects-specification process from a project that was conducted during the fall 2010 and spring of 2011 in this chapter. The project configured and implemented an electronic patient record system at a maternity ward at a hospital located in a European region. The process comprised...... workshops with effects specification with management and end-users and an agile development process including prototypes configured from the effects specifications. We describe the project and the effects-specification process through which effects were related to the system design and instruments...... for measuring effects were designed. The project is analyzed and lessons learned are discussed....

  4. Biological effects of hyperthermia

    International Nuclear Information System (INIS)

    Okumura, Hiroshi

    1980-01-01

    Biological effects of hyperthermia and application of hyperthermia to cancer therapy were outlined. As to independent effects of hyperthermia, heat sensitivity of cancer cells, targets of hyperthermia, thermal tolerance of cancer cells, effects of pH on hyperthermic cell survival, effects of hyperthermia on normal tissues, and possibility of clinical application of hyperthermia were described. Combined effect of hyperthermia and x-irradiation to enhance radiosensitivity of cancer cells, its mechanism, effects of oxygen on cancer cells treated with hyperthermia and irradiation, and therapeutic ratio of combined hyperthermia and irradiation were also described. Finally, sensitizers were mentioned. (Tsunoda, M.)

  5. Side Effects (Management)

    Science.gov (United States)

    ... cancer care is relieving side effects, called symptom management, palliative care, or supportive care. It is important ... treat them. To learn about the symptoms and management of the long-term side effects of cancer ...

  6. Acoustic Casimir Effect

    National Research Council Canada - National Science Library

    Homes, Christopher

    1997-01-01

    ...). When the indirect manifestations of the ZPF are interpreted as due to radiation pressure, acoustic noise can provide an excellent analog to investigate the Casimir effect as well as other effects due to the ZPF...

  7. Multipollutant health effect simulations

    Data.gov (United States)

    U.S. Environmental Protection Agency — Resulting betas (health effects) from a variety of copollutant epidemiologic models used to analyze the impact of exposure measurement error on health effect...

  8. Characteristics of Effective Argumentation.

    Science.gov (United States)

    Frana, Adrian W.

    1989-01-01

    Examines how the 1988 Presidential Debates provide a resource for effective instruction in public argument. Provides several examples of effective (and ineffective) argumentative speaking taken from the debates. (MM)

  9. Climate Effects on Health

    Science.gov (United States)

    ... Guidance and Trainings Webinars Data and Tools Publications Climate Effects on Health Recommend on Facebook Tweet Share ... effects has been excerpted from the Third National Climate Assessment’s Health Chapter . Additional information regarding the health ...

  10. Skills for Effective Consultation.

    Science.gov (United States)

    Dustin, Dick; Ehly, Stewart

    1984-01-01

    Discusses counselor skills that promote effective consultation. Reviews research on effective school consultation and presents a five-stage model which involves phasing in, problem identification, implementation, evaluation, and termination. Provides recommendations for the process and products of consultation. (JAC)

  11. Leadership Effectiveness and Gender

    National Research Council Canada - National Science Library

    Gedney, Christine

    1999-01-01

    This research paper on the subject of Leadership Effectiveness and Gender attempts to conduct a focused amount of research to answer the question about the correlation between gender and leadership effectiveness...

  12. Hormonal effects in newborns

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001911.htm Hormonal effects in newborns To use the sharing features on this page, please enable JavaScript. Hormonal effects in newborns occur because in the womb, babies ...

  13. Medications and Side Effects

    Science.gov (United States)

    ... to fully work. You might feel some side effects of your medication before your feel the benefits – ... as sleepiness, anxiety or headache) is a side effect or a symptom of your illness. Many side ...

  14. Somatic and genetic effects

    International Nuclear Information System (INIS)

    Broerse, J.J.; Barendsen, G.W.; Kal, H.B.; Kogel, A.J. van der

    1983-01-01

    This book contains the extended abstracts of the contributions of the poster workshop sessions on somatic and genetic effects of the 7th international congress of radiation research. They cover the following main topics: haematopoietic and immune systems, mechanisms of late effects in various tissues, endogenous and exogenous factors in radiation carcinogenesis, teratogenic effects, genetic effects, in vitro transformation, tumour induction in different tissues, carcinogenesis in incorporated tissues, cancer epidemology and risk assessment. refs.; figs.; tabs

  15. Habituation of reinforcer effectiveness

    OpenAIRE

    David R Lloyd; David R Lloyd; Douglas J Medina; Larry W Hawk; Whitney D Fosco; Jerry B Richards

    2014-01-01

    In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE) is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We ar...

  16. Effects of teacher training

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne; Larsen, Lea Lund

    2010-01-01

    The article gives a short overview over existing knowledge concerning the effect of teacher training in relation to adult learning. It presents a research design for measuring the effect of teacher traning.......The article gives a short overview over existing knowledge concerning the effect of teacher training in relation to adult learning. It presents a research design for measuring the effect of teacher traning....

  17. Biological radiation effects

    International Nuclear Information System (INIS)

    Kiefer, J.

    1989-01-01

    The book covers all aspects of biological radiation effects. The physical basis is dealt with in some detail, and the effects at the subcellular and the cellular level are discussed, taking into account modern developments and techniques. The effects on the human organism are reviewed, both from the point of view of applications in medicine as well as with regard to radiation hazards (teratogenic, gonadal and carcinogenic effects)

  18. Magnetic effects in electrochemistry

    Directory of Open Access Journals (Sweden)

    NEBOJSA D. NIKOLIC

    2005-05-01

    Full Text Available The effect of imposed magnetic fields onto the electrodeposition of magnetic (nickel and non – magnetic (copper metals was analysed. Also, magnetic properties of electrochemically obtained nanocontacts were examined. An effort to establish a possible correlation between the morphologies of the nanocontacts and the effect of the very large ballistic magnetoresistance (BMR effect was made.

  19. Radiation Therapy Side Effects

    Science.gov (United States)

    Radiation therapy has side effects because it not only kills or slows the growth of cancer cells, it can also affect nearby healthy cells. Many people who get radiation therapy experience fatigue. Other side effects depend on the part of the body that is being treated. Learn more about possible side effects.

  20. Almost sharp quantum effects

    International Nuclear Information System (INIS)

    Arias, Alvaro; Gudder, Stan

    2004-01-01

    Quantum effects are represented by operators on a Hilbert space satisfying 0≤A≤I, and sharp quantum effects are represented by projection operators. We say that an effect A is almost sharp if A=PQP for projections P and Q. We give simple characterizations of almost sharp effects. We also characterize effects that can be written as longer products of projections. For generality we first work in the formalism of von Neumann algebras. We then specialize to the full operator algebra B(H) and to finite dimensional Hilbert spaces

  1. Three-generation neutrino oscillations in curved spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yu-Hao, E-mail: yhzhang1994@gmail.com; Li, Xue-Qian, E-mail: lixq@nankai.edu.cn

    2016-10-15

    Three-generation MSW effect in curved spacetime is studied and a brief discussion on the gravitational correction to the neutrino self-energy is given. The modified mixing parameters and corresponding conversion probabilities of neutrinos after traveling through celestial objects of constant densities are obtained. The method to distinguish between the normal hierarchy and inverted hierarchy is discussed in this framework. Due to the gravitational redshift of energy, in some extreme situations, the resonance energy of neutrinos might be shifted noticeably and the gravitational effect on the self-energy of neutrino becomes significant at the vicinities of spacetime singularities.

  2. Derivation of the cut-off length from the quantum quadratic enhancement of a mass in vacuum energy constant Lambda

    Science.gov (United States)

    Fukushima, Kimichika; Sato, Hikaru

    2018-04-01

    Ultraviolet self-interaction energies in field theory sometimes contain meaningful physical quantities. The self-energies in such as classical electrodynamics are usually subtracted from the rest mass. For the consistent treatment of energies as sources of curvature in the Einstein field equations, this study includes these subtracted self-energies into vacuum energy expressed by the constant Lambda (used in such as Lambda-CDM). In this study, the self-energies in electrodynamics and macroscopic classical Einstein field equations are examined, using the formalisms with the ultraviolet cut-off scheme. One of the cut-off formalisms is the field theory in terms of the step-function-type basis functions, developed by the present authors. The other is a continuum theory of a fundamental particle with the same cut-off length. Based on the effectiveness of the continuum theory with the cut-off length shown in the examination, the dominant self-energy is the quadratic term of the Higgs field at a quantum level (classical self-energies are reduced to logarithmic forms by quantum corrections). The cut-off length is then determined to reproduce today's tiny value of Lambda for vacuum energy. Additionally, a field with nonperiodic vanishing boundary conditions is treated, showing that the field has no zero-point energy.

  3. Network effects in railways

    DEFF Research Database (Denmark)

    Landex, Alex

    2012-01-01

    Railway operation is often affected by network effects as a change in one part of the network can influence other parts of the network. Network effects occur because the train runs may be quite long and since the railway system has a high degree of interdependencies as trains cannot cross....../overtake each other everywhere in the network. First this paper describes network effects in general (section 1). In section 2 the network effects for trains and how they can be measured by scheduled waiting time is described. When the trains are affected by network effects the passengers are also affected....... Therefore, sections 3 and 4 describe the network effects for passengers and how they can be measured using passenger delay models. Before the concluding remarks in section 6, section 5 discusses how the operation can be improved by examining network effects in the planning process. © 2012 WIT Press....

  4. Spread effects - methodology

    International Nuclear Information System (INIS)

    2004-01-01

    Diffusion of technology, environmental effects and rebound effects are the principal effects from the funding of renewable energy and energy economising. It is difficult to estimate the impact of the spread effects both prior to the measures are implemented and after the measures are carried out. Statistical methods can be used to estimate the spread effects, but they are insecure and always need to be complemented with qualitative and subjective evaluations. It is more adequate to evaluate potential spread effects from market and market data surveillance for a selection of technologies and parties. Based on this information qualitative indicators for spread effects can be constructed and used both ex ante and ex post (ml)

  5. Biological radiation effects

    International Nuclear Information System (INIS)

    Gomes, R.A.

    1976-01-01

    The stages of processes leading to radiation damage are studied, as well as, the direct and indirect mechanics of its production. The radiation effects on nucleic acid and protein macro moleculas are treated. The physical and chemical factors that modify radiosensibility are analysed, in particular the oxygen effects, the sensibilization by analogues of nitrogen bases, post-effects, chemical protection and inherent cell factors. Consideration is given to restoration processes by excision of injured fragments, the bloching of the excision restoration processes, the restoration of lesions caused by ionizing radiations and to the restoration by genetic recombination. Referring to somatic effects of radiation, the early ones and the acute syndrome of radiation are discussed. The difference of radiosensibility observed in mammalian cells and main observable alterations in tissues and organs are commented. Referring to delayed radiation effects, carcinogeneses, alterations of life span, effects on growth and development, as well as localized effects, are also discussed [pt

  6. Knudsen effects in a Scott effect experiment.

    Science.gov (United States)

    Wells, C. W.; Wood, L. T.; Hildebrandt, A. F.

    1973-01-01

    A thermal torque sometimes observed in Scott effect measurements has been studied experimentally and an explanation for the thermal torque proposed. The magnitude of the thermal torque can be comparable to the Scott torque depending on geometrical and thermal anisotropies. The thermal torque is predicted to decrease with application of an axial magnetic field.

  7. The effective action

    International Nuclear Information System (INIS)

    DeWitt, B.

    1987-01-01

    The concept of the effective action in quantum field theory was introduced into physics by Julian Schwinger in 1954. The effective action summarizes, in a single functional, all the quantum properties of the fields under consideration. The functional derivative of the effective action yields the effective field equations, which replace the classical field equations as descriptors of the dynamical behavior of quantized fields. Solutions of these equations are 'in-out' matrix elements of the field operators and, when substituted back into the effective action itself, yield logarithms of the corresponding 'in-out' amplitudes. The classical field equations are gauge covariant, a fact that derives from the gauge invariance of the classical action. One has learned how to construct effective actions that are similarly gauge invariant (in each order of perturbation theory) and that yield effective field equations having the covariance properties of their classical analogs. Despite this advance, problems remain, stemming from the fact that there is not one but an infinite number of gauge invariant effective actions, one for every background-covariant choice of supplementary conditions and ghost fields. Vilkovisky (1984) has argued persuasively that by requiring additionally that the effective action be invariant under local invertible changes in the choice of basic field variables, one can construct a natural unique gauge invariant effective action. This lecture will examine Vilkovisky's ideas. 3 refs

  8. Aristotle and Double Effect

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2014-01-01

    There are some interesting similarities between Aristotle’s ‘mixed actions’ in Book III of the Nicomachean Ethics and the actions often thought to be justifiable with the Doctrine of Double Effect. Here I analyse these similarities by comparing Aristotle’s examples of mixed actions with standard...... cases from the literature on double effect such as, amongst others, strategic bombing, the trolley problem, and craniotomy. I find that, despite some common features such as the dilemmatic structure and the inevitability of a bad effect, Aristotle’s mixed actions do not count as cases justifiable...... through application of the Doctrine of Double Effect because they fail to meet the crucial necessary condition of the Doctrine according to which the bad effect can only be a merely foreseen side- effect and not an intended means....

  9. Effective communication with seniors

    OpenAIRE

    PONCAROVÁ, Ester

    2008-01-01

    My bachelor thesis is called "The Effective Communication With Seniors". The aim of this thesis is to describe communication, its various kinds and the basic principles of the effective communication. I will also describe the communication with seniors suffering from dementia. Another aim of this thesis is to find out whether workers in the senior houses know and use the principles of the effective communication.

  10. Multiphoton polarization Bremsstrahlung effect

    International Nuclear Information System (INIS)

    Golovinskij, P.A.

    2001-01-01

    A general approach to induced polarization effects was formulated on the basis of theory of many particles in a strong periodic field. Correlation with the perturbation theory is shown and the types of effective polarization potentials both for isolated atoms and ions, and for ions in plasma, are provided. State of art in the theory of forced polarization Bremsstrahlung effect is analyzed and some outlooks for further experimental and theoretical studies are outlined [ru

  11. Modeling quantization effects in field effect transistors

    International Nuclear Information System (INIS)

    Troger, C.

    2001-06-01

    Numerical simulation in the field of semiconductor device development advanced to a valuable, cost-effective and flexible facility. The most widely used simulators are based on classical models, as they need to satisfy time and memory constraints. To improve the performance of field effect transistors such as MOSFETs and HEMTs these devices are continuously scaled down in their dimensions. Consequently the characteristics of such devices are getting more and more determined by quantum mechanical effects arising from strong transversal fields in the channel. In this work an approach based on a two-dimensional electron gas is used to describe the confinement of the carriers. Quantization is considered in one direction only. For the derivation of a one-dimensional Schroedinger equation in the effective mass framework a non-parabolic correction for the energy dispersion due to Kane is included. For each subband a non-parabolic dispersion relation characterized by subband masses and subband non-parabolicity coefficients is introduced and the parameters are calculated via perturbation theory. The method described in this work has been implemented in a software tool that performs a self-consistent solution of Schroedinger- and Poisson-equation for a one-dimensional cut through a MOS structure or heterostructure. The calculation of the carrier densities is performed assuming Fermi-Dirac statistics. In the case of a MOS structure a metal or a polysilicon gate is considered and an arbitrary gate bulk voltage can be applied. This allows investigating quantum mechanical effects in capacity calculations, to compare the simulated data with measured CV curves and to evaluate the results obtained with a quantum mechanical correction for the classical electron density. The behavior of the defined subband parameters is compared to the value of the mass and the non-parabolicity coefficient from the model due to Kane. Finally the presented characterization of the subbands is applied

  12. The greenhouse effect

    International Nuclear Information System (INIS)

    Berger, A.

    1991-01-01

    The greenhouse effect on earth can be defined as the long wave energy trapped in the atmosphere. Climate forcing and climate system response within which climate feedback mechanisms are contained are determined. Quantitative examples illustrate what could happen if the greenhouse effect is perturbed by human activities, in particular if CO2 atmospheric concentration would double in the future. Recent satellite measurements of the greenhouse effect are given. The net cooling effect of clouds and whether or not there will be less cooling by clouds as the planet warms are also discussed

  13. Rectenna related atmospheric effects

    Science.gov (United States)

    Lee, J.

    1980-01-01

    Possible meteorological effects arising from the existence and operations of a solar power satellite (SPS) system rectenna are examined. Analysis and model simulations in some chosen site situations and meteorological conditions indicate that the meteorological effects of the construction and operation of a rectenna are small, particularly outside the boundary of the structure. From weather and climate points of view, installation of an SPS rectenna seems likely to have effects comparable with those due to other nonindustrial land use changes covering the same area. The absorption and scattering of microwave radiation in the troposphere would have negligible atmospheric effects.

  14. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  15. Leadership Effectiveness and Gender

    National Research Council Canada - National Science Library

    Gedney, Christine

    1999-01-01

    .... It specifically looks at the current definitions of leadership and looks at some historical background information relating to the more common theories that relate to leadership and effectiveness...

  16. Effective Lagrangian of QED

    International Nuclear Information System (INIS)

    Kaminski, J.Z.

    1981-01-01

    A renormalization group equation for the effective Lagrangian of QED is obtained. Starting from this equation, perturbation theory for the renormalization group equation (PTRGE) is developed. The results are in full agreement with the standard perturbation theory. Conjecturing that the asymptotic effective coupling constant is finite, the effective Lagrangian for a strong magnetic field is obtained, which is proportional to the Maxwellian Lagrangian. For the asymptotically free theories the situation is diametrically opposed to QED. In these cases the effective Lagrangian of the Yang-Mills system tends to infinity for very strong external Yang-Mills fields. (Auth.)

  17. Impurity effect in the quantum Nernst effect

    International Nuclear Information System (INIS)

    Shirasaki, Ryoen; Nakamura, Hiroaki; Hatano, Naomichi

    2005-11-01

    We theoretically study the Nernst effect and the Seebeck effect in a two-dimensional electron ga in a strong magnetic field and a temperature gradient under adiabatic condition. We recently predicted for a pure system in the quantum Hall regime that the Nernst coefficients strongly suppressed and the thermal conductance is quantized due to quantum ballistic transport. Taking account of impurities, we here compute the Nernst coefficient and the Seebeck coefficient when the chemical potential coincides with a Landau level. We adopt the self-consistent Born approximation and consider the linear transport equations of the thermal electric transport induced by the temperature gradient. The thermal conductance and the Nernst coefficient are slightly modified from the pure case and the Seebeck coefficient newly appears because of the impurity scattering of electrons in the bulk states. (author)

  18. Masses of the light hadrons in the chiral and cloudy bag models

    International Nuclear Information System (INIS)

    Saito, Koichi.

    1983-10-01

    The masses of the light hadrons except for the pion are calculated in the stable chiral and cloudy bag models with the massless or massive u, d quark and pion. Two difficulties in these models, i.e. the lack of stability and the divergence of the quark self-energy, are removed by taking account of a simple non-local quark-pion interaction. The effects of the finite size of the qq-bar pion and the behavior of the quark self-energy are discussed in detail. In our calculation the bag self-energy due to the pion has an important role in the origin of the N-Δ and the Σ-Λ mass differences. The baryon octet and decuplet masses are well reproduced by the present model. (author)

  19. Binary effectivity rules

    DEFF Research Database (Denmark)

    Keiding, Hans; Peleg, Bezalel

    2006-01-01

    is binary if it is rationalized by an acyclic binary relation. The foregoing result motivates our definition of a binary effectivity rule as the effectivity rule of some binary SCR. A binary SCR is regular if it satisfies unanimity, monotonicity, and independence of infeasible alternatives. A binary...

  20. Summary of geonuclear effects

    International Nuclear Information System (INIS)

    Rawson, Donald E.

    1970-01-01

    Geonuclear effects are considered here to include all of the interactions between underground nuclear explosions and the surrounding earth material. They constitute a large spectrum of effects that starts with the complex chemistry of the explosion 'fireball' and continues in space until the teleseismic signals in the earth have attenuated and in time until the radioactive products have decayed. This paper does not treat the total spectrum but is restricted to those effects which are of direct use to possible non excavation engineering projects and the major side effects that could detract from the use of nuclear explosions for such projects. Emphasis is given to possible methods of enhancing the desired geonuclear effects and minimizing the deleterious ones. Those who have directly participated in developing nuclear explosive technology cannot help but be impressed by the terrific potential for useful work associated with this energy source. Those who have viewed this developing technology from the periphery (the potential industrial market, the concerned public, and specialists in many allied fields) are certainly interested in the potential benefits but cannot help but be impressed by the attendant risks. Some of the useful geonuclear effects balanced against the associated side effects are shown schematically. More experience and increased knowledge of these effects will affect both project costs and public opinion. These factors will determine how the balance will tilt in relation to specific nuclear explosion engineering projects

  1. The polarized EMC effect

    Energy Technology Data Exchange (ETDEWEB)

    W. Bentz; I. C. Cloet; A. W. Thomas

    2007-02-01

    We calculate both the spin independent and spin dependent nuclear structure functions in an effective quark theory. The nucleon is described as a composite quark-diquark state, and the nucleus is treated in the mean field approximation. We predict a sizable polarized EMC effect, which could be confirmed in future experiments.

  2. Effective dose equivalent

    International Nuclear Information System (INIS)

    Huyskens, C.J.; Passchier, W.F.

    1988-01-01

    The effective dose equivalent is a quantity which is used in the daily practice of radiation protection as well as in the radiation hygienic rules as measure for the health risks. In this contribution it is worked out upon which assumptions this quantity is based and in which cases the effective dose equivalent can be used more or less well. (H.W.)

  3. Summary of geonuclear effects

    Energy Technology Data Exchange (ETDEWEB)

    Rawson, Donald E [Explosives Engineering Services, Gulf General Atomic Incorporated, San Diego, CA (United States)

    1970-05-01

    Geonuclear effects are considered here to include all of the interactions between underground nuclear explosions and the surrounding earth material. They constitute a large spectrum of effects that starts with the complex chemistry of the explosion 'fireball' and continues in space until the teleseismic signals in the earth have attenuated and in time until the radioactive products have decayed. This paper does not treat the total spectrum but is restricted to those effects which are of direct use to possible non excavation engineering projects and the major side effects that could detract from the use of nuclear explosions for such projects. Emphasis is given to possible methods of enhancing the desired geonuclear effects and minimizing the deleterious ones. Those who have directly participated in developing nuclear explosive technology cannot help but be impressed by the terrific potential for useful work associated with this energy source. Those who have viewed this developing technology from the periphery (the potential industrial market, the concerned public, and specialists in many allied fields) are certainly interested in the potential benefits but cannot help but be impressed by the attendant risks. Some of the useful geonuclear effects balanced against the associated side effects are shown schematically. More experience and increased knowledge of these effects will affect both project costs and public opinion. These factors will determine how the balance will tilt in relation to specific nuclear explosion engineering projects.

  4. Radiation effects on polyaniline

    International Nuclear Information System (INIS)

    Oki, Yuichi; Kondo, Kenjiro; Suzuki, Takenori; Numajiri, Masaharu; Miura, Taichi; Doi, Shuji; Ohnishi, Toshihiro.

    1992-01-01

    Effects of γ-irradiation on electrical conductivity of polyaniline were investigated. A drastic increase of the conductivity due to radiation-induced doping was observed in combined systems of polyaniline films and halogen-containing polymers. This effect can be applied to measure an integrated radiation dose. (author)

  5. Isotopic effect giant resonances

    International Nuclear Information System (INIS)

    Buenerd, M.; Lebrun, D.; Martin, P.; Perrin, G.; Saintignon, P. de; Chauvin, J.; Duhamel, G.

    1981-10-01

    The systematics of the excitation energy of the giant dipole, monopole, and quadrupole resonances are shown to exhibit an isotopic effect. For a given element, the excitation energy of the transition decreases faster with the increasing neutron number than the empirical laws fitting the overall data. This effect is discussed in terms of the available models

  6. Relative Effects at Work

    NARCIS (Netherlands)

    Braeken, Johan; Mulder, Joris; Wood, Stephen

    2015-01-01

    Assessing the relative importance of predictors has been of historical importance in a variety of disciplines including management, medicine, economics, and psychology. When approaching hypotheses on the relative ordering of the magnitude of predicted effects (e.g., the effects of discrimination

  7. Presenting Food Science Effectively

    Science.gov (United States)

    Winter, Carl K.

    2016-01-01

    While the need to present food science information effectively is viewed as a critical competency for food scientists by the Institute of Food Technologists, most food scientists may not receive adequate training in this area. Effective presentations combine both scientific content and delivery mechanisms that demonstrate presenter enthusiasm for…

  8. The greenhouse effect gases

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the greenhouse effect gases. It presents the greenhouses effect as a key component of the climate system, the impacts of the human activity, the foreseeable consequences of global warming, the Kyoto protocol and Total commitment in the domain. (A.L.B.)

  9. PLEYOTROPIC EFFECTS OF METFORMIN

    Directory of Open Access Journals (Sweden)

    L. Ju. Morgunov

    2014-01-01

    Full Text Available Metformin, traditionally used for the therapy of diabetes mellitus, possesses a number of diverse pleyotropic effects. The drug, in addition to the glucose-lowering actions, has a beneficial effect on components of the metabolic syndrome, significantly reduces body weight.

  10. Genetic effect of neutrons

    International Nuclear Information System (INIS)

    Luchnik, N.V.; Sevan'kaev, A.V.; Fesenko, Eh.V.

    1984-01-01

    Gene mutations resulting from neutron effect are considered, but attention is focused on chromosome mutations. Dose curves for different energy of neutrons obtained at different objects are obtained which makes it possible to consider RBE of neutrons depending on their energy and radiation dose and to get some information on the neutron effect on heredity

  11. Adverse Effects of Bisphosphonates

    DEFF Research Database (Denmark)

    Abrahamsen, Bo

    2010-01-01

    and are tolerated by the majority of patients, but serious adverse events have been recorded in some cases. Only the most common of adverse effects are robustly observable in clinical trials. In general, studies were not powered to detect effects that were lower in incidence than fractures. This review of adverse...

  12. Adverse effects of bisphosphonates

    DEFF Research Database (Denmark)

    Abrahamsen, Bo

    2010-01-01

    and are tolerated by the majority of patients, but serious adverse events have been recorded in some cases. Only the most common of adverse effects are robustly observable in clinical trials. In general, studies were not powered to detect effects that were lower in incidence than fractures. This review of adverse...

  13. RBE for deterministic effects

    International Nuclear Information System (INIS)

    1990-01-01

    In the present report, data on RBE values for effects in tissues of experimental animals and man are analysed to assess whether for specific tissues the present dose limits or annual limits of intake based on Q values, are adequate to prevent deterministic effects. (author)

  14. Radiation effects in space

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1987-07-01

    As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs

  15. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. The overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  16. The greenhouse effect

    International Nuclear Information System (INIS)

    2004-01-01

    In the framework of the sustainable development, this paper presents the greenhouse effect and its impact on the climatic change, the world interest from Rio to Buenos Aires, the human activities producing the carbon dioxide and responsible of the greenhouse effect, the carbon dioxide emission decrease possibilities and shows the necessity of the electric power producers contribution. (A.L.B.)

  17. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Boozer, D.D.; Hulme, B.L.; Daniel, S.L.; Varnado, G.B.; Bennett, H.A.; Chapman, L.D.; Engi, D.

    1976-09-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. In this paper, the overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  18. The Aid Effectiveness Literature

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL consists of empirical macro studies of the effects of development aid. At the end of 2004 it had reached 97 studies of three families, which we have summarized in one study each using meta-analysis. Studies of the effect on investments show that they rise by 1/3 of the aid – the rest is c...

  19. A 'Copenhagen Effect'?

    DEFF Research Database (Denmark)

    Werlauff, Erik

    2009-01-01

    On the basis of the Danish company law reform of 2009/2010, this article examines the question of whether the processes of liberalisation and internationalisation of the Danish rules on public and private companies which the reform represents are significant enough to warrant the term...... the ‘Copenhagen effect' in competition with the already established ‘London effect'....

  20. En "Copenhagen effect"?

    DEFF Research Database (Denmark)

    Werlauff, Erik

    2009-01-01

    Artiklen efterprøver på grundlag af den danske selskabsreform 2009/10, om den liberalisering og internationalisering, der herved har fundet sted af den danske lovgivning om aktie- og anpartsselskaber, er så betydningsfuld, at det fremtidigt giver mening at tale om en "Copenhagen effect" i...... konkurrence med den allerede kendte "London effect". Udgivelsesdato: Juni 2009...

  1. Safeguards system effectiveness modeling

    International Nuclear Information System (INIS)

    Bennett, H.A.; Boozer, D.D.; Chapman, L.D.; Daniel, S.L.; Engi, D.; Hulme, B.L.; Varnado, G.B.

    1976-01-01

    A general methodology for the comparative evaluation of physical protection system effectiveness at nuclear facilities is presently under development. The approach is applicable to problems of sabotage or theft at fuel cycle facilities. In this paper, the overall methodology and the primary analytic techniques used to assess system effectiveness are briefly outlined

  2. Microscopic dynamical Casimir effect

    Science.gov (United States)

    Souza, Reinaldo de Melo e.; Impens, François; Neto, Paulo A. Maia

    2018-03-01

    We consider an atom in its ground state undergoing a nonrelativistic oscillation in free space. The interaction with the electromagnetic quantum vacuum leads to two effects to leading order in perturbation theory. When the mechanical frequency is larger than the atomic transition frequency, the dominant effect is the motion-induced transition to an excited state with the emission of a photon carrying the excess energy. We compute the angular distribution of emitted photons and the excitation rate. On the other hand, when the mechanical frequency is smaller than the transition frequency, the leading-order effect is the parametric emission of photon pairs, which constitutes the microscopic counterpart of the dynamical Casimir effect. We discuss the properties of the microscopic dynamical Casimir effect and build a connection with the photon production by an oscillating macroscopic metallic mirror.

  3. Nocebo effect in dermatology

    Directory of Open Access Journals (Sweden)

    Sidharth Sonthalia

    2015-01-01

    Full Text Available Nocebo effect, originally denoting the negative counterpart of the placebo phenomenon, is now better defined as the occurrence of adverse effects to a therapeutic intervention because the patient expects them to develop. More commonly encountered in patients with a past negative experience, this effect stems from highly active processes in the central nervous system, mediated by specific neurotransmitters and modulated by psychological mechanisms such as expectation and conditioning. The magnitude of nocebo effect in clinical medicine is being increasingly appreciated and its relevance encompasses clinical trials as well as clinical practice. Although there is hardly any reference to the term nocebo in dermatology articles, the phenomenon is encountered routinely by dermatologists. Dermatology patients are more susceptible to nocebo responses owing to the psychological concern from visibility of skin lesions and the chronicity, unpredictable course, lack of ′permanent cure′ and frequent relapses of skin disorders. While finasteride remains the prototypical drug that displays a prominent nocebo effect in dermatologic therapeutics, other drugs such as isotretinoin are also likely inducers. This peculiar phenomenon has recently been appreciated in the modulation of itch perception and in controlled drug provocation tests in patients with a history of adverse drug reactions. Considering the conflict between patients′ right to information about treatment related adverse effects and the likelihood of nocebo effect stemming from information disclosure, the prospect of ethically minimizing nocebo effect remains daunting. In this article, we review the concept of nocebo effect, its postulated mechanism, relevance in clinical dermatology and techniques to prevent it from becoming a barrier to effective patient management.

  4. [Psychoanalysis and Side Effect].

    Science.gov (United States)

    Shirahase, Joichiro

    2015-01-01

    A study of psychoanalysis from the perspective of side effects reveals that its history was a succession of measures to deal with its own side effects. This, however, does not merely suggest that, as a treatment method, psychoanalysis is incomplete and weak: rather, its history is a record of the growth and development of psychoanalysis that discovered therapeutic significance from phenomena that were initially regarded as side effects, made use of these discoveries, and elaborated them as a treatment method. The approach of research seen during the course of these developments is linked to the basic therapeutic approach of psychoanalysis. A therapist therefore does not draw conclusions about a patient's words and behaviors from a single aspect, but continues to make efforts to actively discover a variety of meanings and values from them, and to make the patient's life richer and more productive. This therapeutic approach is undoubtedly one of the unique aspects of psychoanalysis. I discuss the issue of psychoanalysis and side effects with the aim of clarifying this unique characteristic of psychoanalysis. The phenomenon called resistance inevitably emerges during the process of psychoanalytic treatment. Resistance can not only obstruct the progress of therapy; it also carries the risk of causing a variety of disadvantages to the patient. It can therefore be seen as an adverse effect. However, if we re-examine this phenomenon from the perspective of transference, we find that resistance is in fact a crucial tool in psychoanalysis, and included in its main effect, rather than a side effect. From the perspective of minimizing the character of resistance as a side effect and maximizing its character as a main effect, I have reviewed logical organization, dynamic evaluation, the structuring of treatment, the therapist's attitudes, and the training of therapists. I conclude by stating that psychoanalysis has aspects that do not match the perspective known as a side

  5. Coexistence of Velocity Renormalization and Ferrimagnetic Fluctuation in the Organic Dirac Electron System α-(BEDT-TTF)2I3

    Science.gov (United States)

    Matsuno, Genki; Kobayashi, Akito

    2018-05-01

    We evaluate the uniform spin susceptibility in an extended Hubbard model describing α-(BEDT-TTF)2I3. Employing the Fock-type self-energy with the long-range Coulomb interaction and the random phase approximation with the on-site Coulomb interaction, it is clarified that the characteristic energy scales at which ferrimagnetic fluctuation and velocity renormalization emerge are different. This is why these phenomena coexist while the ferrimagnetic fluctuation is disturbed by the velocity renormalization. In addition, it is found that screening effect to the self-energy is irrelevant in the presence of a strong on-site Coulomb interaction U.

  6. Electroplastic effect in metals

    International Nuclear Information System (INIS)

    Sprecher, A.F. Jr.

    1984-01-01

    This report presents the effects of single d-c current pulses (1000-6000 A/mm 2 approx.60 μs) on plastically deforming metals. Polycrystalline wire specimens (D 0 approx. 1/2 mm, L 0 approx. 50 mm) representing the three more common crystal structures were employed: Ti from the HCP structures; Fe, Nb, and W from the bcc structure; and Al, Cu, and Ni from the fcc structure. The tests were carried out under uniaxial tension with an applied strain rate of 1.7 x 10 -4 sec -1 at room temperature. Forced air cooling was employed in order to reduce the principal side effect, heating. As a result of applying a current pulse, there were significant drops in the flow stress (1-35%). These drops not only included an electron dislocation interaction but all side effects as well. The main side effect due to the temperature rise was thermal expansion and could account for 60-90% of the drops. In addition to thermal expansion, some thermally induced plastic flow occurred as indicated by computer simulations. The total side effects (thermal expansion and plastic flow) approximately accounted for the stress drops in Ti, W, and Nb. However, a strong electron dislocation (ed) interaction was observed in Cu and Al since plastic flow from thermal effects was negligible. In Ni and Fe the portion of the stress drops due to (ed) was unclear due to some dynamic aging effects present

  7. Noncovalent Hydrogen Isotope Effects

    Science.gov (United States)

    Buchachenko, A. L.; Breslavskaya, N. N.

    2018-02-01

    Zero-point energies (ZPE) and isotope effects, induced by intermolecular, noncovalent vibrations, are computed and tested by experimental data. The ZPE differences of H- and D-complexes of water with hydrogen, methane, and water molecules are about 100-300 cal/mol; they result to isotope effects IE of 1.20-1.70. Semi-ionic bonds between metal ions and water ligands in M(H2O) 6 2+ complexes are much stronger; their ZPEs are about 12-14 kcal/mol per molecule and result to IE of 1.9-2.1 at 300 K. Protonated (deuterated) water and biwater exhibit the largest ZPE differences and isotope effects; the latter are 25-28 and 12-13 for water and biwater, respectively. Noncovalent IEs contribute markedly into the experimentally measured effects and explain many anomalous and even magic properties of the effects, such as the dependence of IE on the solvents and on the presence of the third substances, enormously large isotope effects at the mild conditions, the difference between IEs measured in the reactions of individual protiated and deuterated compounds and those measured in their mixture. Noncovalent IEs are not negligible and should be taken into account to make correct and substantiated conclusions on the reaction mechanisms. The kinetic equations are derived for the total isotope effects, which include noncovalent IEs as additive factors.

  8. Bystander effects and radiotherapy.

    Science.gov (United States)

    Marín, Alicia; Martín, Margarita; Liñán, Olga; Alvarenga, Felipe; López, Mario; Fernández, Laura; Büchser, David; Cerezo, Laura

    2015-01-01

    Radiation-induced bystander effects are defined as biological effects expressed after irradiation by cells whose nuclei have not been directly irradiated. These effects include DNA damage, chromosomal instability, mutation, and apoptosis. There is considerable evidence that ionizing radiation affects cells located near the site of irradiation, which respond individually and collectively as part of a large interconnected web. These bystander signals can alter the dynamic equilibrium between proliferation, apoptosis, quiescence or differentiation. The aim of this review is to examine the most important biological effects of this phenomenon with regard to areas of major interest in radiotherapy. Such aspects include radiation-induced bystander effects during the cell cycle under hypoxic conditions when administering fractionated modalities or combined radio-chemotherapy. Other relevant aspects include individual variation and genetics in toxicity of bystander factors and normal tissue collateral damage. In advanced radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), the high degree of dose conformity to the target volume reduces the dose and, therefore, the risk of complications, to normal tissues. However, significant doses can accumulate out-of-field due to photon scattering and this may impact cellular response in these regions. Protons may offer a solution to reduce out-of-field doses. The bystander effect has numerous associated phenomena, including adaptive response, genomic instability, and abscopal effects. Also, the bystander effect can influence radiation protection and oxidative stress. It is essential that we understand the mechanisms underlying the bystander effect in order to more accurately assess radiation risk and to evaluate protocols for cancer radiotherapy.

  9. Effective field theories

    International Nuclear Information System (INIS)

    Mack, G.; Kalkreuter, T.; Palma, G.; Speh, M.

    1992-05-01

    Effective field theories encode the predictions of a quantum field theory at low energy. The effective theory has a fairly low utraviolet cutoff. As a result, loop corrections are small, at least if the effective action contains a term which is quadratic in the fields, and physical predictions can be read straight from the effective Lagrangean. Methods will be discussed how to compute an effective low energy action from a given fundamental action, either analytically or numerically, or by a combination of both methods. Basically, the idea is to integrate out the high frequency components of fields. This requires the choice of a 'blockspin', i.e. the specification af a low frequency field as a function of the fundamental fields. These blockspins will be fields of the effective field theory. The blockspin need not be a field of the same type as one of the fundamental fields, and it may be composite. Special features of blockspin in nonabelian gauge theories will be discussed in some detail. In analytical work and in multigrid updating schemes one needs interpolation kernels A from coarse to fine grid in addition to the averaging kernels C which determines the blockspin. A neural net strategy for finding optimal kernels is presented. Numerical methods are applicable to obtain actions of effective theories on lattices of finite volume. The special case of a 'lattice' with a single site (the constraint effective potential) is of particular interest. In a higgs model, the effective action reduces in this case to the free energy, considered as a function of a gauge covariant magnetization. Its shape determines the phase structure of the theory. Its loop expansion with and without gauge fields can be used to determine finite size corrections to numerical data. (orig.)

  10. Cohomology of Effect Algebras

    Directory of Open Access Journals (Sweden)

    Frank Roumen

    2017-01-01

    Full Text Available We will define two ways to assign cohomology groups to effect algebras, which occur in the algebraic study of quantum logic. The first way is based on Connes' cyclic cohomology. The resulting cohomology groups are related to the state space of the effect algebra, and can be computed using variations on the Kunneth and Mayer-Vietoris sequences. The second way involves a chain complex of ordered abelian groups, and gives rise to a cohomological characterization of state extensions on effect algebras. This has applications to no-go theorems in quantum foundations, such as Bell's theorem.

  11. Creating more effective graphs

    CERN Document Server

    Robbins, Naomi B

    2012-01-01

    A succinct and highly readable guide to creating effective graphs The right graph can be a powerful tool for communicating information, improving a presentation, or conveying your point in print. If your professional endeavors call for you to present data graphically, here's a book that can help you do it more effectively. Creating More Effective Graphs gives you the basic knowledge and techniques required to choose and create appropriate graphs for a broad range of applications. Using real-world examples everyone can relate to, the author draws on her years of experience in gr

  12. Ballistic missile defense effectiveness

    Science.gov (United States)

    Lewis, George N.

    2017-11-01

    The potential effectiveness of ballistic missile defenses today remains a subject of debate. After a brief discussion of terminal and boost phase defenses, this chapter will focus on long-range midcourse defenses. The problems posed by potential countermeasures to such midcourse defenses are discussed as are the sensor capabilities a defense might have available to attempt to discriminate the actual missile warhead in a countermeasures environment. The role of flight testing in assessing ballistic missile defense effectiveness is discussed. Arguments made about effectiveness by missile defense supporters and critics are summarized.

  13. Effective career ladders.

    Science.gov (United States)

    Bryant, B; Rabbitts, D; Shover, J; Torres, M; VanDerHeyden, B; Violand-Jones, S

    1992-01-01

    Motivation, quality improvement, productivity enhancement. These are just some of the benefits of an effective career ladder program. The key term here is effective. It is easy for laboratory personnel to stagnate professionally if they do not have a career ladder program, but it is even easier for them to become frustrated--even cynical--over a program that fails to live up to its expectations to encourage, support, and reward professional advancement. If you have been looking form some ideas to get your own career ladder program off the ground, the following responses from your colleagues may help as CLMR asks: What makes your career ladder program effective?

  14. Developing Effective Performance Measures

    Science.gov (United States)

    2014-10-14

    University When Performance Measurement Goes Bad Laziness Vanity Narcissism Too Many Pettiness Inanity 52 Developing Effective...Kasunic, October 14, 2014 © 2014 Carnegie Mellon University Narcissism Measuring performance from the organization’s point of view, rather than from

  15. Space radiation effects

    International Nuclear Information System (INIS)

    Li Shiqing; Yan Heping

    1995-01-01

    The authors briefly discusses the radiation environment in near-earth space and it's influences on material, and electronic devices using in space airship, also, the research developments in space radiation effects are introduced

  16. Vascular Effects of Histamine

    African Journals Online (AJOL)

    olayemitoyin

    effects of histamine are mediated via H1 and H2 receptors and the actions are modulated by H3 receptor subtype located on presynaptic ... neurotransmittion in the central nervous system and .... Autoinhibition of brain histamine release.

  17. Side Effects: Sleep Problems

    Science.gov (United States)

    Sleep problems are a common side effect during cancer treatment. Learn how a polysomnogram can assess sleep problems. Learn about the benefits of managing sleep disorders in men and women with cancer.

  18. Authoring Effective Demonstrations

    National Research Council Canada - National Science Library

    Fu, Dan; Jensen, Randy; Salas, Eduardo; Rosen, Michael A; Ramachandran, Sowmya; Upshaw, Christin L; Hinkelman, Elizabeth; Lampton, Don

    2007-01-01

    ... or human role-players for each training event. We report our ongoing efforts to (1) research the nature and purpose of demonstration, articulating guidelines for effective demonstration within a training context, and (2...

  19. Flexo-photovoltaic effect.

    Science.gov (United States)

    Yang, Ming-Min; Kim, Dong Jik; Alexe, Marin

    2018-04-19

    It is highly desirable to discover photovoltaic mechanisms that enable a higher efficiency of solar cells. Here, we report that the bulk photovoltaic effect, which is free from the thermodynamic Shockley-Queisser limit but usually manifested only in noncentrosymmetric (piezoelectric or ferroelectric) materials, can be realized in any semiconductor, including silicon, by mediation of flexoelectric effect. We introduce strain gradients using either an atomic force microscope or a micron-scale indentation system, creating giant photovoltaic currents from centrosymmetric single crystals of SrTiO 3 , TiO 2 , and Si. This strain-gradient-induced bulk photovoltaic effect, which we call the flexo-photovoltaic effect, functions in the absence of a p - n junction. This finding may extend present solar cell technologies by boosting the solar energy conversion efficiency from a wide pool of established semiconductors. Copyright © 2018, American Association for the Advancement of Science.

  20. Pictorial Superiority Effect

    Science.gov (United States)

    Nelson, Douglas L.; And Others

    1976-01-01

    Pictures generally show superior recognition relative to their verbal labels. This experiment was designed to link this pictorial superiority effect to sensory or meaning codes associated with the two types of symbols. (Editor)

  1. Network-Based Effectiveness

    National Research Council Canada - National Science Library

    Friman, Henrik

    2006-01-01

    ... (extended from Leavitt, 1965). This text identifies aspects of network-based effectiveness that can benefit from a better understanding of leadership and management development of people, procedures, technology, and organizations...

  2. Antihypertensive Effects of Probiotics.

    Science.gov (United States)

    Robles-Vera, Iñaki; Toral, Marta; Romero, Miguel; Jiménez, Rosario; Sánchez, Manuel; Pérez-Vizcaíno, Francisco; Duarte, Juan

    2017-04-01

    The present review focuses in the hypertension-associated changes in the microbiota and the current insights regarding the impact of probiotics on blood pressure in animal models and in human hypertensive patients. Gut dysbiosis in hypertension is characterized by (i) the gut microbioma that is less diverse and less rich with an increased Firmicutes/Bacteroidetes ratio and (ii) a decrease in acetate- and butyrate-producing bacteria and an increase in lactate-producing bacterial populations. The meta-analysis of the human studies supports that supplementation with probiotics reduces blood pressure. The mechanism of this antihypertensive effect of probiotics and its protective effect on endothelial function has not been fully elucidated. Further investigations are needed to clarify if the effects of probiotic bacteria result from the changes in the gut microbiota and its metabolic by-products; the restoration of the gut barrier function; and the effects on endotoxemia, inflammation, and renal sympathetic nerve activity.

  3. Frost Effects Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Full-scale study in controlled conditionsThe Frost Effects Research Facility (FERF) is the largest refrigerated warehouse in the United States that can be used for a...

  4. Radiation effects in space

    International Nuclear Information System (INIS)

    Fry, R.J.M.

    1986-01-01

    The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented

  5. The effective nuclear potential

    International Nuclear Information System (INIS)

    Skyrme, T.H.R.

    1994-01-01

    An empirical analyses is made of the mean effective internucleon potential required in the shell-model description of nuclei, allowing for the presence of many-body effects as suggested by current theory. A consistent description is found in which the effective two-body interaction acts almost entirely in even states, and the many-body effects are simulated by a repulsive three-body contact interaction. The strength of the two-body interaction is consistent with that expressed by the free scattering matrix of the two-nucleon system, and that of the three-body interaction with the 'rearrangement energy' calculated in the many-body theory. (author). 21 refs, 2 figs, 7 tabs

  6. Greenhouse effect and climate

    International Nuclear Information System (INIS)

    Flohn, H.

    1987-01-01

    Model calculations with different marginal conditions and different physical processes do, on the basis of realistic assumptions, result in a temperature rise of 3 ± 1.5degC at doubling carbon dioxide concentrations. Temperatures are increasing even more due to the presence of trace gases contributing to the greenhouse effect. They are assumed to be having a share of 100% in the carbon dioxide effect (additive) in 30-40 years from now. According to the model calculations the CO 2 increase from about 280 ppm around 1850 to 345 ppm (1985) is equal to a globally averaged temperature rise of 0.5-0.7degC. As the data obtained before 1900 were incomplete and little representative climatic analyses cannot be considered to have been effective but after that time. However, considering the additional influence of other climatic effects such as vulcanism the temperature rise satisfactorily corresponds to the values obtained since 1900. (orig./HP) [de

  7. The Effects: Economy

    Science.gov (United States)

    Nutrient pollution has diverse and far-reaching effects on the U.S. economy, impacting tourism, property values, commercial fishing, recreational businesses and many other sectors that depend on clean water.

  8. Conditions for Effectiveness.

    Science.gov (United States)

    Wright, Jeannette T.

    1988-01-01

    The most effective college presidents are those whose leadership styles are dominant, decisive, and when appropriate, autocratic. The president has to believe profoundly in the intrinsic value of the college. (Author/MSE)

  9. Density dependent effective interactions

    International Nuclear Information System (INIS)

    Dortmans, P.J.; Amos, K.

    1994-01-01

    An effective nucleon-nucleon interaction is defined by an optimal fit to select on-and half-off-of-the-energy shell t-and g-matrices determined by solutions of the Lippmann-Schwinger and Brueckner-Bethe-Goldstone equations with the Paris nucleon-nucleon interaction as input. As such, it is seen to better reproduce the interaction on which it is based than other commonly used density dependent effective interactions. The new (medium modified) effective interaction when folded with appropriate density matrices, has been used to define proton- 12 C and proton- 16 O optical potentials. With them elastic scattering data are well fit and the medium effects identifiable. 23 refs., 8 figs

  10. Side Effects: Fatigue

    Science.gov (United States)

    Fatigue is a common side effect of many cancer treatments such as chemotherapy, radiation therapy, immunotherapy, and surgery. Anemia and pain can also cause fatigue. Learn about symptoms and way to manage fatigue.

  11. Side Effects: Diarrhea

    Science.gov (United States)

    Diarrhea, a side effect of cancer treatment, may cause symptoms such as loose, watery stools. Diarrhea can lead to dehydration and malnutrition in cancer patients. Learn about ways to treat and manage diarrhea during cancer treatment.

  12. Side Effects: Appetite Loss

    Science.gov (United States)

    Cancer treatments may lower your appetite. Side effects such as nausea, fatigue, or mouth sores can also making eating difficult. Learn how to eat well to avoid losing weight or becoming dehydrated, so you stay strong during treatment.

  13. Side Effects: Pain

    Science.gov (United States)

    Controlling pain is an important part of your cancer treatment plan. Learn how to track levels of pain. Find out how pain, a side effect of cancer treatment, is treated using acupuncture, biofeedback, and physical therapy.

  14. the effects of Garlic

    African Journals Online (AJOL)

    This study evaluated the effects of Garlic (Allium sativum) on taste responses and relative organ weights in albino rats. Graded dietary ... Allium sativum commonly known as garlic is a specie in the onion ..... nitrate induced toxicity in male mice.

  15. Deforestation Hydrological Effects

    International Nuclear Information System (INIS)

    Poveda J, G.; Mesa S, O.J.

    1995-01-01

    Deforestation causes strong disturbances in ecosystems and in hydrological cycle, increasing or reducing wealths. Particularly in this work, effects of feed back between interface processes land - atmosphere are discussed and is demonstrated that losses of water by evaporation-transpiration are thoroughly indispensable to maintain the balance of hydrological regime. It's concluded that as a rule the effect of deforestation is to reduce wealth middle and to increase extreme wealth with consequent stronger and more frequent droughts or flood effects. Other deforestation effects as increase in superficial temperature, increase in atmospherical pressure, decrease in soil moisture, decrease in evaporation-transpiration, decrease of soil ruggedness, decrease of thickness of atmospherical cap limit, decrease of clouds, decrease of rain in both medium and long term and the consequent decrease of rivers wealth middle are explained. Of other side, the basins with greater deforestation affectation in Colombia are indicated. Finally, it's demonstrated the need of implementing reforestation programs

  16. Side Effects: Anemia

    Science.gov (United States)

    Anemia is a side effect of cancer treatments, including chemotherapy and radiation therapy. It can make women and men feel fatigued, dizzy, and short of breath. Learn how to manage fatigue caused by anemia during cancer treatment.

  17. Theory of Effectiveness Measurement

    National Research Council Canada - National Science Library

    Bullock, Richard K

    2006-01-01

    Effectiveness measures provide decision makers feedback on the impact of deliberate actions and affect critical issues such as allocation of scarce resources, as well as whether to maintain or change existing strategy...

  18. EFFECTS OF GLOBAL WARMING

    OpenAIRE

    Dr. Basanti Jain

    2017-01-01

    The abnormal increase in the concentration of the greenhouse gases is resulting in higher temperatures. We call this effect is global warming. The average temperature around the world has increased about 1'c over 140 years, 75% of this has risen just over the past 30 years. The solar radiation, as it reaches the earth, produces "greenhouse effect" in the atmosphere. The thick atmospheric layers over the earth behaves as a glass surface, as it permits short wave radiations from coming in, but ...

  19. Modulational effects in accelerators

    International Nuclear Information System (INIS)

    Satogata, T.

    1997-01-01

    We discuss effects of field modulations in accelerators, specifically those that can be used for operational beam diagnostics and beam halo control. In transverse beam dynamics, combined effects of nonlinear resonances and tune modulations influence diffusion rates with applied tune modulation has been demonstrated. In the longitudinal domain, applied RF phase and voltage modulations provide mechanisms for parasitic halo transport, useful in slow crystal extraction. Experimental experiences with transverse tune and RF modulations are also discussed

  20. The quantum hall effect

    International Nuclear Information System (INIS)

    El-Arabi, N. M.

    1993-01-01

    Transport phenomena in two dimensional semiconductors have revealed unusual properties. In this thesis these systems are considered and discussed. The theories explain the Integral Quantum Hall Effect (IQHE) and the Fractional Quantum Hall Effect (FQHE). The thesis is composed of five chapters. The first and the second chapters lay down the theory of the IQHE, the third and fourth consider the theory of the FQHE. Chapter five deals with the statistics of particles in two dimension. (author). Refs

  1. Advertising Effectiveness In Events

    OpenAIRE

    Jain, Sushilkumar

    2012-01-01

    Confronted with decreasing effectiveness of the classic marketing communications, events have become an increasingly popular alternative for marketers. Events constitute one of the most exciting and fastest growing forms of leisure and business. With time, the decreasing effectiveness of classical marketing communications boosted the use of events for marketing and making brand awareness. Event marketing is seen as the unique opportunity to integrate the firm’s communication activities like p...

  2. Nuclear medium effects on the K{sup Macron Low-Asterisk} meson

    Energy Technology Data Exchange (ETDEWEB)

    Tolos, Laura, E-mail: tolos@ice.csic.es [Instituto de Ciencias del Espacio (IEEC/CSIC) Campus Universitat Autonoma de Barcelona, Facultat de Ciencies, Torre C5, E-08193 Bellaterra (Barcelona) (Spain); Molina, Raquel; Oset, Eulogio [Instituto de Fisica Corpuscular (centro mixto CSIC-UV), Institutos de Investigacion de Paterna, Aptdo. 22085, 46071 Valencia (Spain); Ramos, Angels [Departament d' Estructura i Constituents de la Materia, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)

    2012-05-01

    The K{sup Macron Low-Asterisk} meson in dense matter is analyzed by means of a unitary approach in coupled channels based on the local hidden gauge formalism. The K{sup Macron Low-Asterisk} self-energy and the corresponding K{sup Macron Low-Asterisk} spectral function in the nuclear medium are obtained. We observe that the K{sup Macron Low-Asterisk} develops a width in matter up to five times bigger than in free space. We also estimate the transparency ratio of the {gamma}A{yields}K{sup +}K{sup Low-Asterisk -}A{sup Prime} reaction. This ratio is an excellent tool to detect experimentally modifications of the K{sup Macron Low-Asterisk} meson in dense matter.

  3. Superconductivity versus quantum criticality: Effects of thermal fluctuations

    Science.gov (United States)

    Wang, Huajia; Wang, Yuxuan; Torroba, Gonzalo

    2018-02-01

    We study the interplay between superconductivity and non-Fermi liquid behavior of a Fermi surface coupled to a massless SU(N ) matrix boson near the quantum critical point. The presence of thermal infrared singularities in both the fermionic self-energy and the gap equation invalidates the Eliashberg approximation, and makes the quantum-critical pairing problem qualitatively different from that at zero temperature. Taking the large N limit, we solve the gap equation beyond the Eliashberg approximation, and obtain the superconducting temperature Tc as a function of N . Our results show an anomalous scaling between the zero-temperature gap and Tc. For N greater than a critical value, we find that Tc vanishes with a Berezinskii-Kosterlitz-Thouless scaling behavior, and the system retains non-Fermi liquid behavior down to zero temperature. This confirms and extends previous renormalization-group analyses done at T =0 , and provides a controlled example of a naked quantum critical point. We discuss the crucial role of thermal fluctuations in relating our results with earlier work where superconductivity always develops due to the special role of the first Matsubara frequency.

  4. High Burnup Effects Program

    International Nuclear Information System (INIS)

    Barner, J.O.; Cunningham, M.E.; Freshley, M.D.; Lanning, D.D.

    1990-04-01

    This is the final report of the High Burnup Effects Program (HBEP). It has been prepared to present a summary, with conclusions, of the HBEP. The HBEP was an international, group-sponsored research program managed by Battelle, Pacific Northwest Laboratories (BNW). The principal objective of the HBEP was to obtain well-characterized data related to fission gas release (FGR) for light water reactor (LWR) fuel irradiated to high burnup levels. The HBEP was organized into three tasks as follows: Task 1 -- high burnup effects evaluations; Task 2 -- fission gas sampling; and Task 3 -- parameter effects study. During the course of the HBEP, a program that extended over 10 years, 82 fuel rods from a variety of sources were characterized, irradiated, and then examined in detail after irradiation. The study of fission gas release at high burnup levels was the principal objective of the program and it may be concluded that no significant enhancement of fission gas release at high burnup levels was observed for the examined rods. The rim effect, an as yet unquantified contributor to athermal fission gas release, was concluded to be the one truly high-burnup effect. Though burnup enhancement of fission gas release was observed to be low, a full understanding of the rim region and rim effect has not yet emerged and this may be a potential area of further research. 25 refs., 23 figs., 4 tabs

  5. Synchronization on effective networks

    International Nuclear Information System (INIS)

    Zhou Tao; Zhao Ming; Zhou Changsong

    2010-01-01

    The study of network synchronization has attracted increasing attentionrecently. In this paper, we strictly define a class of networks, namely effective networks, which are synchronizable and orientable networks. We can prove that all the effective networks with the same size have the same spectra, and are of the best synchronizability according to the master stability analysis. However, it is found that the synchronization time for different effective networks can be quite different. Further analysis shows that the key ingredient affecting the synchronization time is the maximal depth of an effective network: the larger depth results in a longer synchronization time. The secondary factor is the number of links. The increasing number of links connecting nodes in the same layer (horizontal links) will lead to longer synchronization time, whereas the increasing number of links connecting nodes in neighboring layers (vertical links) will accelerate the synchronization. Our analysis of the relationship between the structure and synchronization properties of the original and effective networks shows that the purely directed effective network can provide an approximation of the original weighted network with normalized input strength. Our findings provide insights into the roles of depth, horizontal and vertical links in the synchronizing process, and suggest that the spectral analysis is helpful yet insufficient for the comprehensive understanding of network synchronization.

  6. Synchronization on effective networks

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Tao [Web Sciences Center, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhao Ming [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Zhou Changsong, E-mail: cszhou@hkbu.edu.h [Department of Physics, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2010-04-15

    The study of network synchronization has attracted increasing attentionrecently. In this paper, we strictly define a class of networks, namely effective networks, which are synchronizable and orientable networks. We can prove that all the effective networks with the same size have the same spectra, and are of the best synchronizability according to the master stability analysis. However, it is found that the synchronization time for different effective networks can be quite different. Further analysis shows that the key ingredient affecting the synchronization time is the maximal depth of an effective network: the larger depth results in a longer synchronization time. The secondary factor is the number of links. The increasing number of links connecting nodes in the same layer (horizontal links) will lead to longer synchronization time, whereas the increasing number of links connecting nodes in neighboring layers (vertical links) will accelerate the synchronization. Our analysis of the relationship between the structure and synchronization properties of the original and effective networks shows that the purely directed effective network can provide an approximation of the original weighted network with normalized input strength. Our findings provide insights into the roles of depth, horizontal and vertical links in the synchronizing process, and suggest that the spectral analysis is helpful yet insufficient for the comprehensive understanding of network synchronization.

  7. The Lisse effect revisited.

    Science.gov (United States)

    Weeks, Edwin P

    2002-01-01

    The Lisse effect is a rarely noted phenomenon occurring when infiltration caused by intense rain seals the surface soil layer to airflow, trapping air in the unsaturated zone. Compression of air by the advancing front results in a pressure increase that produces a water-level rise in an observation well screened below the water table that is several times as large as the distance penetrated by the wetting front. The effect is triggered by intense rains and results in a very rapid water-level rise, followed by a recession lasting a few days. The Lisse effect was first noted and explained by Thal Larsen in 1932 from water-level observations obtained in a shallow well in the village of Lisse, Holland. The original explanation does not account for the increased air pressure pushing up on the bottom of the wetting front. Analysis of the effect of this upward pressure indicates that a negative pressure head at the base of the wetting front, psi(f), analogous to that postulated by Green and Ampt (1911) to explain initially rapid infiltration rates into unsaturated soils, is involved in producing the Lisse effect. Analysis of recorded observations of the Lisse effect by Larsen and others indicates that the water-level rise, which typically ranges from 0.10 to 0.55 m, should be only slightly larger than psi(f) and that the depth of penetration of the wetting front is no more than several millimeters.

  8. Habituation of reinforcer effectiveness

    Directory of Open Access Journals (Sweden)

    David R Lloyd

    2014-01-01

    Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

  9. Edge effects in composites

    International Nuclear Information System (INIS)

    Guz, A.N.; Kokhanenko, Yu.V.

    1995-01-01

    In the present article we survey papers on edge effects investigated by the rigorous approach. We interpret edge effects as stressed states created in a composite as a result of zones in which the stresses exhibit a rapidly changing behavior in comparison with the slow variation of the stresses outside such zones. Here the range of the edge effect is defined as the distance from the point of its inception to the boundary of the edge zone in a given direction. The transition of the stresses to the slowly varying state is determined within prescribed error limits. The size and configuration of the edge zone depends on the tolerated error. Clearly, the main difficulty associated with the rigorous approach is finding solutions of the elasticity problems. The finite-difference approach is suggested for the approximate solution of these problems. In light of the comparative time consumption of the finite-difference approach, it is best directed at certain classes of problems rather than at particular individual problems. Not too many papers on the investigation of edge effects by the rigorous approach have been published to date. Below, following in their footsteps, we formulate edge effect problems in composites, determine classes of problems, and investigate edge effects in composite materials and structural elements using them in Cartesian (planar and three-dimensional problems) and cylindrical (axisymmetric problems) coordinate frames. We note that the division of approaches to the study of edge effects into qualitative (nonrigorous) and quantitative (rigorous) reflects the authors own point of view. Of course, other schemes of classification of the approaches to the investigation of the regions of rapidly varying states in composites are possible

  10. Radiation effects and radioprotectors

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, R.K., E-mail: dr_rajendra_purohit@yahoo.co.in [Radiation Biology Laboratory, Department of Zoology, Govt. Dungar College, Bikaner (India); Bugalia, Saroj [Department of Zoology, S.K. Kalyan College, Sikar (India); Dakshene, Monika [Department of Chemistry, Govt. College, Kota (India)

    2012-07-01

    Radiation exposure causes damage to biological systems and these damages are mediated by the generation of free radicals and reactive oxygen species targeting vital cellular components such as DNA and membranes. DNA repair systems and the endogenous cellular biochemical defense mechanisms against reactive oxygen species and antioxidants enzymes like reduced Glutathione (GSH), Superoxide dismutase, Glutathione peroxidase catalase etc. fail upon exposures to higher as well as chronic radiation doses leading to alterations in cell functions, cell death or mutations. Radioprotectors prevent these alterations and protect cells and tissues from the deleterious effects of radiations. Radioprotectors are of great importance due to their possible and potential application during planned radiation exposures such as radiotherapy, diagnostic scanning, clean up operations in nuclear accidents, space expeditions etc. and Unplanned radiations exposures such as accidents in nuclear industry, nuclear terrorism, natural background radiation etc. Many of the available synthetic radioprotectors are toxic to mammalian system at doses required to be effective as radioprotector. Increasing uses of ionizing radiation have drawn the attention of many radiobiologists towards their undesired side effects produced in various tissues and for modifying them to facilitate the beneficial uses of radiation. Modification of radiation response is obtained by means of chemical substances that can significantly decrease the magnitude of response when present in a biological system during irradiation. Radioprotectors are chemicals that modify a cell's response to radiation. Radioprotectors are drugs that protect normal (non cancerous) cells from the damage caused by radiation therapy. These agents promote the repair of normal cells that are exposed to radiation. Various chemicals, like Cysteamine, MPG , WR-2721 have been tested for the protection against harmful effects of radiation. These radio

  11. Radiation effects and radioprotectors

    International Nuclear Information System (INIS)

    Purohit, R.K.; Bugalia, Saroj; Dakshene, Monika

    2012-01-01

    Radiation exposure causes damage to biological systems and these damages are mediated by the generation of free radicals and reactive oxygen species targeting vital cellular components such as DNA and membranes. DNA repair systems and the endogenous cellular biochemical defense mechanisms against reactive oxygen species and antioxidants enzymes like reduced Glutathione (GSH), Superoxide dismutase, Glutathione peroxidase catalase etc. fail upon exposures to higher as well as chronic radiation doses leading to alterations in cell functions, cell death or mutations. Radioprotectors prevent these alterations and protect cells and tissues from the deleterious effects of radiations. Radioprotectors are of great importance due to their possible and potential application during planned radiation exposures such as radiotherapy, diagnostic scanning, clean up operations in nuclear accidents, space expeditions etc. and Unplanned radiations exposures such as accidents in nuclear industry, nuclear terrorism, natural background radiation etc. Many of the available synthetic radioprotectors are toxic to mammalian system at doses required to be effective as radioprotector. Increasing uses of ionizing radiation have drawn the attention of many radiobiologists towards their undesired side effects produced in various tissues and for modifying them to facilitate the beneficial uses of radiation. Modification of radiation response is obtained by means of chemical substances that can significantly decrease the magnitude of response when present in a biological system during irradiation. Radioprotectors are chemicals that modify a cell's response to radiation. Radioprotectors are drugs that protect normal (non cancerous) cells from the damage caused by radiation therapy. These agents promote the repair of normal cells that are exposed to radiation. Various chemicals, like Cysteamine, MPG , WR-2721 have been tested for the protection against harmful effects of radiation. These radio

  12. Spin Hall effects

    Science.gov (United States)

    Sinova, Jairo; Valenzuela, Sergio O.; Wunderlich, J.; Back, C. H.; Jungwirth, T.

    2015-10-01

    Spin Hall effects are a collection of relativistic spin-orbit coupling phenomena in which electrical currents can generate transverse spin currents and vice versa. Despite being observed only a decade ago, these effects are already ubiquitous within spintronics, as standard spin-current generators and detectors. Here the theoretical and experimental results that have established this subfield of spintronics are reviewed. The focus is on the results that have converged to give us the current understanding of the phenomena, which has evolved from a qualitative to a more quantitative measurement of spin currents and their associated spin accumulation. Within the experimental framework, optical-, transport-, and magnetization-dynamics-based measurements are reviewed and linked to both phenomenological and microscopic theories of the effect. Within the theoretical framework, the basic mechanisms in both the extrinsic and intrinsic regimes are reviewed, which are linked to the mechanisms present in their closely related phenomenon in ferromagnets, the anomalous Hall effect. Also reviewed is the connection to the phenomenological treatment based on spin-diffusion equations applicable to certain regimes, as well as the spin-pumping theory of spin generation used in many measurements of the spin Hall angle. A further connection to the spin-current-generating spin Hall effect to the inverse spin galvanic effect is given, in which an electrical current induces a nonequilibrium spin polarization. This effect often accompanies the spin Hall effect since they share common microscopic origins. Both can exhibit the same symmetries when present in structures comprising ferromagnetic and nonmagnetic layers through their induced current-driven spin torques or induced voltages. Although a short chronological overview of the evolution of the spin Hall effect field and the resolution of some early controversies is given, the main body of this review is structured from a pedagogical

  13. Magnetoelectric effects in manganites

    Science.gov (United States)

    Jeen, Hyoung Jeen

    Research on manganites has been conducted for more than half century. Recent discoveries of colossal responses to external fields such as colossal magnetoresistance effects and correlation among spin, orbital, and lattice in phase separated manganites and multiferroic manganites have motivated me to understand these materials. The main purpose of this dissertation is to understand magnetoelectric effects in phase separated (La1-yPr y)1-xCaxMnO3 (LPCMO) thin films and multiferroic BiMnO3 (BMO) thin films. First, high quality phase separated manganite thin films have been successfully grown. To grow the high quality manganite thin films, extensive effort was devoted to fine tuning of oxygen pressure, temperature, and laser fluence during film growth. As-grown films were characterized with various ex-situ techniques: magnetization measurements, transport measurements, x-ray diffraction, atomic force microscopy, and/or transmission electron microscopy to remove the effects of impurities and unwanted strains except substrate induced strain. Second, three major results were obtained in high quality phase separated LPCMO thin films. These results are based on the dynamic nature of phases in LPCMO. 1) LPCMO thin films showed single domain to multi-domain transition during cooling. This transition can be tuned by substrate stress induced in-plane magnetic anisotropy. 2) Evidence for the origin of colossal electroresistance (CER) effect has been observed. The CER is triggered by dielectrophoresis, or movements of ferromagnetic metallic (FMM) phase, which is manifested in anisotropic transport properties in microfabricated LPCMO cross structures. This fluidic nature of the FMM phase in LPCMO under high electric fields lead to exotic magnetoelectric effects. 3) Electric field effects on magnetotransport properties have been observed. This phenomena can also be tuned by the combined effect of substrate strain and current flow. This combined effect of electric and magnetic

  14. Pharmacological effects of biotin.

    Science.gov (United States)

    Fernandez-Mejia, Cristina

    2005-07-01

    In the last few decades, more vitamin-mediated effects have been discovered at the level of gene expression. Increasing knowledge on the molecular mechanisms of these vitamins has opened new perspectives that form a connection between nutritional signals and the development of new therapeutic agents. Besides its role as a carboxylase prosthetic group, biotin regulates gene expression and has a wide repertoire of effects on systemic processes. The vitamin regulates genes that are critical in the regulation of intermediary metabolism: Biotin has stimulatory effects on genes whose action favors hypoglycemia (insulin, insulin receptor, pancreatic and hepatic glucokinase); on the contrary, biotin decreases the expression of hepatic phosphoenolpyruvate carboxykinase, a key gluconeogenic enzyme that stimulates glucose production by the liver. The findings that biotin regulates the expression of genes that are critical in the regulation of intermediary metabolism are in agreement with several observations that indicate that biotin supply is involved in glucose and lipid homeostasis. Biotin deficiency has been linked to impaired glucose tolerance and decreased utilization of glucose. On the other hand, the diabetic state appears to be ameliorated by pharmacological doses of biotin. Likewise, pharmacological doses of biotin appear to decrease plasma lipid concentrations and modify lipid metabolism. The effects of biotin on carbohydrate metabolism and the lack of toxic effects of the vitamin at pharmacological doses suggest that biotin could be used in the development of new therapeutics in the treatment of hyperglycemia and hyperlipidemia, an area that we are actively investigating.

  15. NEUROTROPHIC EFFECTS OF ETIFOXINE

    Directory of Open Access Journals (Sweden)

    I. Yu. Torshin

    2016-01-01

    Full Text Available Higher anxiety results in the decreased levels of various neurotrophic factors and enkephalins and in impaired production of proinflammatory cytokines. The anxiolytic etifoxine is used to treat anxiety states and adjustment disorders. Etifoxine modulates the GABAergic transmission and metabolism of neurosteroids. The latter determines the unique neurotrophic and neuroprotective properties of the drug, such as increased expression of neurotrophic factors, regeneration of nerve fibers, and preservation and regeneration of myelin sheaths. Other important pharmacological effects of an etifoxine molecule have been also discovered; these are to relieve allodynia related to 3α-steroids and GABA receptors and to effectively treat cerebral edema, experimental autoimmune encephalitis, and excessive nervous excitability in the presence of alcohol withdrawal. In addition, the chemoreactome simulation of the molecule of etifoxine has established that its attenuated side effects are due to its lower interaction with serotonin, acetylcholine, adrenergic and other neurotransmitter receptors than is shown by benzodiazepines. Etifoxine has been also found to have anti-inflammatory (due to antihistamine and antileukotriene effects and antitumor activities and an ability to affect hemodynamics and vessel walls.The paper presents a systematic analysis of the results of trials of the neurotrophic properties of etifoxine. It considers how the drug stimulates the expression of neurotrophic factors, accelerates the maturation and regeneration of nerve fibers, and regenerates myelin sheaths.The neurotrophic effects of etifoxine along with its anxiolytic activity will accelerate the recovery of patients with different neurological diseases and enhance the quality of their neurorehabilitation.

  16. Pleiotropic effects of statins

    Directory of Open Access Journals (Sweden)

    Narasaraju Kavalipati

    2015-01-01

    Full Text Available Statins or 3-hydroxy-methylglutaryl coenzyme A (HMG CoA reductase inhibitors not only prevents the synthesis of cholesterol biosynthesis but also inhibits the synthesis of essential isoprenoid intermediates such as farnesyl pyrophosphate, geranylgeranyl pyrophosphate, isopentanyl adenosine, dolichols and polyisoprenoid side chains of ubiquinone, heme A, and nuclear lamins. These isoprenoid intermediates are required for activation of various intracellular/signaling proteins- small guanosine triphosphate bound protein Ras and Ras-like proteins like Rho, Rab, Rac, Ral, or Rap which plays an indispensible role in multiple cellular processes. Reduction of circulating isoprenoids intermediates as a result of HMG CoA reductase inhibition by statins prevents activation of these signalling proteins. Hence, the multiple effects of statins such as antiinflammatory effects, antioxidant effects, antiproliferative and immunomodulatory effects, plaque stability, normalization of sympathetic outflow, and prevention of platelet aggregation are due to reduction of circulating isoprenoids and hence inactivation of signalling proteins. These multiple lipid-independent effects of statins termed as statin pleiotropy would potentially open floodgates for research in multiple treatment domains catching attentions of researchers and clinician across the globe.

  17. Heavy particle effects

    International Nuclear Information System (INIS)

    Yao, Y.P.

    1981-01-01

    There are two problems discussed, both of which have to do with dissimilar magnitudes in mass. Theoretically, we can devise the large difference in mass as observed by decreeing some vev, v/sub i/ to be much bigger than the other; or, we can assume that some couplings g/sub i/ are much stronger. These two different assumptions give rise to entirely different patterns of interaction in the resulting theory. The first way to generate a mass hierarchy can be called the soft way, because in the zeroth order, the large mass scale leaves its foot print merely in a few effective parameters of the residual theory. The effective theory is renormalizable, sans anomaly. In this limit, the heavy particles decouple. The second assumption (g/sub j/ much greater than g/sub j'/) to create mass hierarchy does a lot of violence to a theory. Effects of the large mass scale will be felt by the system left behind in many ways. An infinite number of parameters are needed to summarize the effects in this limit. This is called the hard limit. It follows that the resulting effective Lagrangian, if in fact it makes sense to construct one at all, will be non-polynomial and apparently non-renormalizable

  18. Relative age effect: implications for effective practice.

    Science.gov (United States)

    Andronikos, Georgios; Elumaro, Adeboye Israel; Westbury, Tony; Martindale, Russell J J

    2016-01-01

    Physical and psychological differences related to birthdate amongst athletes of the same selection year have been characterised as the "relative age effects" (RAEs). RAEs have been identified in a variety of sports, both at youth and adult level, and are linked with dropout of athletes and a reduction of the talent pool. This study examined the existence, mechanisms and possible solutions to RAEs using qualitative methodology. Seven experts in the field of talent identification and development were interviewed. Inductive analysis of the data showed that, while there was mixed evidence for the existence of RAEs across sports, the eradication of RAEs was attributed to controllable features of the development environment. The factors reported included the structure of "categories" used to group athletes within the sport (e.g. age, weight, size, skills), recognition and prioritisation of long-term development over "short term win focus." Education of relevant parties (e.g. coaches, scouts, clubs) about RAEs and the nature of "talent" within a long-term context was suggested, along with careful consideration of the structure of the development environment (e.g. delayed selection, provision for late developers, focus on skills not results, use of challenge). Implications for research and practice are discussed.

  19. Biophysical radiation effects

    International Nuclear Information System (INIS)

    Fidorra, J.

    1982-07-01

    The biological effectiveness of ionizing radiation is based upon the absorption of energy in molecular structures of a cell. Because of the quantum nature of radiation large fluctuations of energy concentration in subcellulare regions has to be considered. In addition both the spatial distribution of a sensitive molecular target and cellulare repair processes has to be taken into consideration for an assessment of radiation action. In radiation protection the difference between the quality factor and the Relative Biological Effectiveness has a fundamental meaning and will be discussed in more detail. The present report includes a short review on some relevant models on radiation action and a short discussion on effects of low dose irradiation. (orig.) [de

  20. Improving nuclear regulatory effectiveness

    International Nuclear Information System (INIS)

    2001-01-01

    Ensuring that nuclear installations are operated and maintained in such a way that their impact on public health and safety is as low as reasonably practicable has been and will continue to be the cornerstone of nuclear regulation. In the past, nuclear incidents provided the main impetus for regulatory change. Today, economic factors, deregulation, technological advancements, government oversight and the general requirements for openness and accountability are leading regulatory bodies to review their effectiveness. In addition, seeking to enhance the present level of nuclear safety by continuously improving the effectiveness of regulatory bodies is seen as one of the ways to strengthen public confidence in the regulatory systems. This report covers the basic concepts underlying nuclear regulatory effectiveness, advances being made and future requirements. The intended audience is primarily nuclear safety regulators, but government authorities, nuclear power plant operators and the general public may also be interested. (author)

  1. Security effectiveness review (SER)

    International Nuclear Information System (INIS)

    Kouprianova, I.; Ek, D.; Showalter, R.; Bergman, M.

    1998-01-01

    As part of the on-going DOE/Russian MPC and A activities at the Institute of Physics and Power Engineering (IPPE) and in order to provide a basis for planning MPC and A enhancements, an expedient method to review the effectiveness of the MPC and A system has been adopted. These reviews involve the identification of appropriate and cost-effective enhancements of facilities at IPPE. This effort requires a process that is thorough but far less intensive than a traditional vulnerability assessment. The SER results in a quick assessment of current and needed enhancements. The process requires preparation and coordination between US and Russian analysts before, during, and after information gathering at the facilities in order that the analysis is accurate, effective, and mutually agreeable. The goal of this paper is to discuss the SER process, including the objectives, time scale, and lessons learned at IPPE

  2. Effective Nutritional Supplement Combinations

    Science.gov (United States)

    Cooke, Matt; Cribb, Paul J.

    Few supplement combinations that are marketed to athletes are supported by scientific evidence of their effectiveness. Quite often, under the rigor of scientific investigation, the patented combination fails to provide any greater benefit than a group given the active (generic) ingredient. The focus of this chapter is supplement combinations and dosing strategies that are effective at promoting an acute physiological response that may improve/enhance exercise performance or influence chronic adaptations desired from training. In recent years, there has been a particular focus on two nutritional ergogenic aids—creatine monohydrate and protein/amino acids—in combination with specific nutrients in an effort to augment or add to their already established independent ergogenic effects. These combinations and others are discussed in this chapter.

  3. Radiomimetic effects of meclofenoxate

    International Nuclear Information System (INIS)

    Meier, K.; Mehlhorn, D.

    1990-01-01

    Meclofenoxate, a nootropic, by virtue of its chemical nature is an ester of p-chlorophenoxyacetic acid and dimethylaminoethanol. On top of its typical indications, particular attention was given to its radiomimetic effect to which evidence had been produced on tissue cultures by Sladek, 1977. Animal experiments were conducted to investigate the effect in the context of a transplantation tumour. One single locally delimited X-ray irradiation with concomitant administration of meclofenoxate was applied to the animals. 14 days after tumour transplantation. The radiomimetic effect of meclofenoxate was confirmed under the conditions chosen for the animal experiments. However, no confirmation was obtained for the assumption of p-chlorophenoxyacetic acid being the only active substance. (author)

  4. Quantum Zeno effect

    International Nuclear Information System (INIS)

    Petrosky, T.; Tasaki, S.; Prigogine, I.

    1991-01-01

    In 1977, Misra and Sudarshan showed, based on the quantum measurement theory, that an unstable particle will never be found to decay when it is continuously observed. They called it the quantum Zeno effect (or paradox). More generally the quantum Zeno effect is associated to the inhibition of transitions by frequent measurements. This possibility has attracted much interest over the last years. Recently, Itano, Heinzen, Bollinger and Wineland have reported that they succeeded in observing the quantum Zeno effect. This would indeed be an important step towards the understanding of the role of the observer in quantum mechanics. However, in the present paper, we will show that their results can be recovered through conventional quantum mechanics and do not involve a repeated reduction (or collapse) of the wave function. (orig.)

  5. Heavy rain effects

    Science.gov (United States)

    Dunham, R. Earl, Jr.

    1994-01-01

    This paper summarizes the current state of knowledge of the effect of heavy rain on airplane performance. Although the effects of heavy rain on airplane systems and engines are generally known, only recently has the potential aerodynamic effect of heavy rain been recognized. In 1977 the United States Federal Aviation Administration (FAA) conducted a study of 25 aircraft accidents and incidents which occurred between 1964 and 1976 in which low-altitude wind shear could have been a contributing factor. Of the 25 cases (23 approach or landing and 2 take-off) in the study, ten cases had occurred in a rain environment, and in five cases these were classified as intense or heavy rain encounters. These results led to the reconsideration of high-intensity, short-duration rainfall as a potential weather-related aircraft safety hazard, particularly in the take-off and/or approach phases of flight.

  6. Biological effects of neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ogiu, Toshiaki; Ohmachi, Yasushi; Ishida, Yuka [National Inst. of Radiological Sciences, Chiba (JP)] [and others

    2003-03-01

    Although the occasion to be exposed to neutrons is rare in our life, except for nuclear accidents like in the critical accident at Tokai-mura in 1999, countermeasures against accident should be always prepared. In the Tokai-mura accident, residents received less than 21 mSv of neutrons and gamma rays. The cancer risks and fetal effects of low doses of neutrons were matters of concern among residents. The purpose of this program is to investigate the relative biological effectiveness (RBE) for leukemias, and thereby to assess risks of neutrons. Animal experiments are planed to obtain the following RBEs: (1) RBE for the induction of leukemias in mice and (2) RBE for effects on fetuses. Cyclotron fast neutrons (10 MeV) and electrostatic accelerator-derived neutrons (2 MeV) are used for exposure in this program. Furthermore, cytological and cytogenetic analyses will be performed. (author)

  7. Stereoelectronic Substituent Effects

    DEFF Research Database (Denmark)

    Bols, Mikael; Jensen, Henrik Helligsø

    2006-01-01

    An investigation was carried Out on the influence of the stereo-chemistry of substituents, particularly hydroxyl groups, on their electronic effects in piperidines, carbohydrates (pyranosides), and related compounds. Polar groups, such as OH, OR, and F, were found in the 3 and 4 position to be much...... more electron-withdrawing when positioned equatorially rather than axially. In contrast, little difference in electronic effects was observed from apolar groups as a result of epimerization. These observations were believed to be caused by differences in charge-dipole interactions and were used...... to explain why stereoisomeric glycosides hydrolyze with different rates. The conformational changes of hydroxylated piperidines and related compounds as a function of pH were likewise explained from the different substituent effects of axial and equatorial OH groups....

  8. Bystander effects of radiation

    International Nuclear Information System (INIS)

    Umar, Neethu Fathima; Daniel, Nittu

    2013-01-01

    The Radiation-Induced Bystander Effect is the phenomenon in which unirradiated cells show irradiated effects due to the signals received from nearby irradiated cells. Evidence suggests that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells. Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population. When cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation. The demonstration of a bystander effect in human tissues and, more recently, in whole organisms have clear implication of the potential relevance of the non-targeted response to human health. This effect may also contribute to the final biological consequences of exposure to low doses of radiation. The radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation, in that extranuclear and extracellular events may also contribute to the final biological consequences of exposure to low doses of radiation. Multiple pathways are involved in the bystander phenomenon, and different cell types respond differently to bystander signalling. Using cDNA microarrays, a number of cellular signalling genes, including cyclooxygenase-2 (CQX-2), have been shown to be casually linked to the bystander phenomenon. The observation that inhibition of the phosphorylation of extracellular signal-related kinase (ERK) suppressed the bystander response further confirmed the important role of the mitogen-activated protein kinase (MAPK) signalling cascade in the bystander process. The cells deficient in mitochondrial DNA showed a significantly reduced response to bystander signalling, suggesting a functional role of mitochondria in the signalling process. (author)

  9. Habituation of reinforcer effectiveness.

    Science.gov (United States)

    Lloyd, David R; Medina, Douglas J; Hawk, Larry W; Fosco, Whitney D; Richards, Jerry B

    2014-01-09

    In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect "accelerated-HRE." Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

  10. Greenhouse effects on Venus

    Science.gov (United States)

    Bell, Peter M.

    Calculations that used Pioneer-Venus measurements of atmosphere composition, temperature profiles, and radiative heating predicted Venus' surface temperature ‘very precisely,’ says the Ames Research Center. The calculations predict not only Venus' surface temperature but agree with temperatures measured at various altitudes above the surface by the four Pioneer Venus atmosphere probe craft.Using Pioneer-Venus spacecraft data, a research team has virtually proved that the searing 482° C surface temperature of Venus is due to an atmospheric greenhouse effect. Until now the Venus greenhouse effect has been largely a theory.

  11. Low doses effects

    International Nuclear Information System (INIS)

    Tubiana, M.

    1997-01-01

    In this article is asked the question about a possible carcinogens effect of low dose irradiation. With epidemiological data, knowledge about the carcinogenesis, the professor Tubiana explains that in spite of experiments made on thousand or hundred of thousands animals it has not been possible to bring to the fore a carcinogens effect for low doses and then it is not reasonable to believe and let the population believe that low dose irradiation could lead to an increase of neoplasms and from this point of view any hardening of radiation protection standards could in fact, increase anguish about ionizing radiations. (N.C.)

  12. Effective quantum field theories

    International Nuclear Information System (INIS)

    Georgi, H.M.

    1993-01-01

    The most appropriate description of particle interactions in the language of quantum field theory depends on the energy at which the interactions are studied; the description is in terms of an ''effective field theory'' that contains explicit reference only to those particles that are actually important at the energy being studied. The various themes of the article are: local quantum field theory, quantum electrodynamics, new physics, dimensional parameters and renormalizability, socio-dynamics of particle theory, spontaneously broken gauge theories, scale dependence, grand unified and effective field theories. 2 figs

  13. Harnessing greenhouse effect

    International Nuclear Information System (INIS)

    Meunier, F.; Rivet, P.; Terrier, M.F.

    2005-01-01

    This book considers the energy and greenhouse effect questions in a global way. It presents the different methods of fight against the increase of the greenhouse effect (energy saving, carbon sinks, cogeneration,..), describes the main alternative energy sources to fossil fuels (biomass, wind power, solar, nuclear,..), and shows that, even worrying, the future is not so dark as it seems to be and that technical solutions exist which will allow to answer the worldwide growing up energy needs and to slow down the climatic drift. (J.S.)

  14. Nonequilibrium effects in Isoscaling

    International Nuclear Information System (INIS)

    Dorso, C. O.; Lopez, J. A.

    2007-01-01

    In this work we study within a simple model different properties of the system that allow us to understand the properties of the isoscaling observable. We first show that isoscaling is a general property of fragmenting systems. We show this by using a simple generalized percolation model. We show that the usual isoscaling property can be obtained in the case of bond percolation in bichromatic lattices with any regular topology. In this case the probabilities of each color (isospin) are independent. We then explore the effect of introducing 'non-equilibrium' effects

  15. The Lazarus effect

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    Members of the RD39 collaboration stage a demonstration of the Lazarus effect in the CERN cryolab. At the LHC experiments, the front-line inner detectors - trackers - will be traversed by a mammoth thousand million million passing particles per square centimetre over the lifetimes of the experiments. After long exposure to passing particles, defects appear in the silicon and the signal is destroyed. A group of physicists at Bern University have found that at temperatures below 100 K, dead detectors apparently come back to life. They're calling their discovery the Lazarus effect after the Biblical character raised from the dead by Jesus after he had been entombed for four days.

  16. Climate, greenhouse effect, energy

    International Nuclear Information System (INIS)

    Henriksen, Thormod; Kanestroem, Ingolf

    2001-01-01

    The book has sections on the sun as energy source, the earth climate and it's changes and factors influencing this, the greenhouse effect on earth and other planets, greenhouse gases and aerosols and their properties and importance, historic climate and paleoclimate, climatic models and their uses and limitations, future climate, consequences of climatic changes, uncertainties regarding the climate and measures for reducing the greenhouse effect. Finally there are sections on energy and energy resources, the use, sources such as fossil fuels, nuclear power, renewable resources, heat pumps, energy storage and environmental aspects and the earth magnetic field is briefly surveyed

  17. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Koshimizu, S.

    1992-01-01

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  18. The Vampire Effect

    DEFF Research Database (Denmark)

    Erfgen, Carsten; Zenker, Sebastian; Sattler, Henrik

    2015-01-01

    Although many brand managers favor the use of celebrities in advertisements, others worry that celebrities overshadow the brand and thus impair brand recall. Practitioners refer to this overshadowing as the vampire effect, defined as a decrease in brand recall for an advertising stimulus...... that features a celebrity endorser versus the same stimulus with an unknown but equally attractive endorser. Because there is no agreement about whether this overshadowing really exists, this research analyzes the existence of the vampire effect and its moderators in a series of experiments with a total of 4...

  19. Level width broadening effect

    International Nuclear Information System (INIS)

    Zhang Jingshang

    2003-01-01

    In file-6 for double-differential cross sections, the level width broadening effect should be taken into account properly due to Heisenberg' uncertainty. Besides level width broadening effect, the energy resolution in the measurements is also needed in fitting measurement procedure. In general, the traditional normal Gaussian expansion is employed. However, to do so in this way the energy balance could not be held. For this reason, the deformed Gaussian expansion functions with exponential form for both the single energy point and continuous spectrum are introduced, with which the normalization and energy balance conditions could be held exactly in the analytical form. (author)

  20. Proactively evaluating training effectiveness

    International Nuclear Information System (INIS)

    Fetterman, Harry E.

    2003-01-01

    A common model of the five phase Systematic Approach to Training (SAT) displays the fifth phase, evaluation, feeding back into the previous four phases: analysis, design, development, and implementation. Evaluating training effectiveness in PP and L's Nuclear Department is not simply the fifth phase of the SAT. PP and L has demonstrated a more effective methodology is realized when evaluation is built into each of the other four phases. At PP and L, evaluation is conducted formatively throughout the first four phases of the SAT process and summatively after implementation. (author)

  1. The quantized Hall effect

    International Nuclear Information System (INIS)

    Klitzing von, K.

    1989-01-01

    The quantized Hall effect is theoretically explained in detail as are its basic properties. The explanation is completed with the pertinent mathematical relations and illustrative figures. Experimental data are critically assessed obtained by quantum transport measurement in a magnetic field on two-dimensional systems. The results are reported for a MOSFET silicon transistor and for GaAs-Al x Ga 1-x As heterostructures. The application is discussed of the quantized Hall effect in determining the fine structure constant or in implementing the resistance standard. (M.D.). 27 figs., 57 refs

  2. Analgesic effects of melatonin

    DEFF Research Database (Denmark)

    Wilhelmsen, Michael; Amirian, Ilda; Reiter, Russel J

    2011-01-01

    studies, melatonin shows potent analgesic effects in a dose-dependent manner. In clinical studies, melatonin has been shown to have analgesic benefits in patients with chronic pain (fibromyalgia, irritable bowel syndrome, migraine). The physiologic mechanism underlying the analgesic actions of melatonin...... has not been clarified. The effects may be linked to G(i) -coupled melatonin receptors, to G(i) -coupled opioid µ-receptors or GABA-B receptors with unknown downstream changes with a consequential reduction in anxiety and pain. Also, the repeated administration of melatonin improves sleep and thereby...

  3. Analgesic effects of melatonin

    DEFF Research Database (Denmark)

    Wilhelmsen, Michael; Amirian, Ilda; Reiter, Russel J

    2011-01-01

    studies, melatonin shows potent analgesic effects in a dose-dependent manner. In clinical studies, melatonin has been shown to have analgesic benefits in patients with chronic pain (fibromyalgia, irritable bowel syndrome, migraine). The physiologic mechanism underlying the analgesic actions of melatonin...... has not been clarified. The effects may be linked to G(i) -coupled melatonin receptors, to G(i) -coupled opioid μ-receptors or GABA-B receptors with unknown downstream changes with a consequential reduction in anxiety and pain. Also, the repeated administration of melatonin improves sleep and thereby...

  4. Solvent effects in chemistry

    CERN Document Server

    Buncel, Erwin

    2015-01-01

    This book introduces the concepts, theory and experimental knowledge concerning solvent effects on the rate and equilibrium of chemical reactions of all kinds.  It begins with basic thermodynamics and kinetics, building on this foundation to demonstrate how a more detailed understanding of these effects may be used to aid in determination of reaction mechanisms, and to aid in planning syntheses. Consideration is given to theoretical calculations (quantum chemistry, molecular dynamics, etc.), to statistical methods (chemometrics), and to modern day concerns such as ""green"" chemistry, where ut

  5. Training effectiveness evaluation model

    International Nuclear Information System (INIS)

    Penrose, J.B.

    1993-01-01

    NAESCO's Training Effectiveness Evaluation Model (TEEM) integrates existing evaluation procedures with new procedures. The new procedures are designed to measure training impact on organizational productivity. TEEM seeks to enhance organizational productivity through proactive training focused on operation results. These results can be identified and measured by establishing and tracking performance indicators. Relating training to organizational productivity is not easy. TEEM is a team process. It offers strategies to assess more effectively organizational costs and benefits of training. TEEM is one organization's attempt to refine, manage and extend its training evaluation program

  6. Massive states in chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

    1995-08-01

    It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)

  7. Quantum Scalar Corrections to the Gravitational Potentials on de Sitter Background

    NARCIS (Netherlands)

    Park, Sohyun; Prokopec, Tomislav; Woodard, R. P.

    We employ the graviton self-energy induced by a massless, minimally coupled (MMC) scalar on de Sitter background to compute the quantum corrections to the gravitational potentials of a static point particle with a mass $M$. The Schwinger-Keldysh formalism is used to derive real and causal effective

  8. On the exponentiation of leading infrared divergences in massless Yang-Mills theories

    International Nuclear Information System (INIS)

    Frenkel, J.; Garcia, R.L.

    1977-01-01

    We derive, in the axial gauge, the effective U-matrix which governs the behaviour of leading infrared singularities in the self-energy functions of Yang-Mills particles. We then show in a very simple manner, that these divergences, which determine the leading singularities in massless Yang-Mills theories, exponentiate [pt

  9. Charmed hadrons in nuclear medium

    NARCIS (Netherlands)

    Tolos, L.; Gamermann, D.; Garcia-Recio, C.; Molina, R.; Nieves, J.; Oset, E.; Ramos, A.

    We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a self-consistent manner We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the

  10. Quasi-particle properties in a quasi-two-dimensional electron liquid

    Indian Academy of Sciences (India)

    effects are incorporated into the local-field factors that describe the charge and spin correla- ... dient of which is the quasi-particle concept and its interactions. .... factors. Note that we have approximated the local-field factors by their static, frequency-independent limits. Quite generally, once the QP self-energy is known, the ...

  11. Dynamic phonon exchange requires consistent dressing

    International Nuclear Information System (INIS)

    Hahne, F.J.W.; Engelbrecht, C.A.; Heiss, W.D.

    1976-01-01

    It is shown that states with undersirable properties (such as ghosts, states with complex eigenenergies and states with unrestricted normalization) emerge from two-body calculations using dynamic effective interactions if one is not careful in introducing single-particle self-energy insertions in a consistent manner

  12. Ward identities at finite temperature

    International Nuclear Information System (INIS)

    DOlivo, J.C.; Torres, M.; Tututi, E.

    1996-01-01

    The Ward identities for QED at finite temperature are derived using the functional real-time formalism. They are verified by an explicit one-loop calculation. An effective causal vertex is constructed which satisfy the Ward identity with the associated retarded self-energy. copyright 1996 American Institute of Physics

  13. The EMC effect

    International Nuclear Information System (INIS)

    Norton, P R

    2003-01-01

    The status of the EMC effect, the anomalous scattering of leptons on nuclei, is reviewed, together with models which have been formulated to explain it. The implications for other processes are discussed, in particular the relevance to problems in conventional nuclear physics

  14. The service bullwhip effect

    NARCIS (Netherlands)

    Akkermans, H.A.; Voss, C.

    2013-01-01

    Purpose This paper sets out to explore whether and how the bullwhip effect, as found in product supply chains, might also manifest itself in services, as well as what policies can be successful for mitigating it. Design/methodology/approach A combination of analytic methods was used—inductive case

  15. Thermosensory reversal effect quantified

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kappers, A.M.L.

    2008-01-01

    At room temperature, some materials feel colder than others due to differences in thermal conductivity, heat capacity and geometry. When the ambient temperature is well above skin temperature, the roles of 'cold' and 'warm' materials are reversed. In this paper, this effect is quantified by

  16. Thermosensory reversal effect quantified

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kappers, A.M.L.

    2008-01-01

    At room temperature, some materials feel colder than others due to differences in thermal conductivity, heat capacity and geometry. When the ambient temperature is well above skin temperature, the roles of ‘cold’ and ‘warm’ materials are reversed. In this paper, this effect is quantified by

  17. Squeezing the Efimov effect

    DEFF Research Database (Denmark)

    Sandoval, J. H.; Bellotti, F. F.; Yamashita, M. T.

    2018-01-01

    The quantum mechanical three-body problem is a source of continuing interest due to its complexity and not least due to the presence of fascinating solvable cases. The prime example is the Efimov effect where infinitely many bound states of identical bosons can arise at the threshold where the tw...

  18. Biological Effects of Radiation

    International Nuclear Information System (INIS)

    Jatau, B.D.; Garba, N.N.; Yusuf, A.M.; Yamusa, Y. A.; Musa, Y.

    2013-01-01

    In earlier studies, researchers aimed a single particle at the nucleus of the cell where DNA is located. Eighty percent of the cells shot through the nucleus survived. This contradicts the belief that if radiation slams through the nucleus, the cell will die. But the bad news is that the surviving cells contained mutations. Cells have a great capacity to repair DNA, but they cannot do it perfectly. The damage left behind in these studies from a single particle of alpha radiation doubled the damage that is already there. This proved, beyond a shadow of doubt, those there biological effects occur as a result of exposure to radiation, Radiation is harmful to living tissue because of its ionizing power in matter. This ionization can damage living cells directly, by breaking the chemical bonds of important biological molecules (particularly DNA), or indirectly, by creating chemical radicals from water molecules in the cells, which can then attack the biological molecules chemically. At some extent these molecules are repaired by natural biological processes, however, the effectiveness of this repair depends on the extent of the damage. The interaction of ionizing with the human body, arising either from external sources outside the body or from internal contamination of the body by radioactive materials, leads to the biological effects which may later show up as a clinical symptoms. Basically, this formed the baseline of this research to serve as a yardstick for creating awareness about radiation and its resulting effects.

  19. Beam-Beam Effects

    International Nuclear Information System (INIS)

    Herr, W; Pieloni, T

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities

  20. Radiation effects on superconductivity

    International Nuclear Information System (INIS)

    Brown, B.S.

    1975-01-01

    The effect of radiation on the superconducting transition temperature (T/sub c/), upper critical field (H/sub c2/), and volume-pinning-force density (F/sub p/) were discussed for the three kinds of superconducting material (elements, alloys, and compounds). 11 figures, 3 tables, 86 references

  1. Radiation effects at ISABELLE

    International Nuclear Information System (INIS)

    Sanger, P.A.; Danby, G.T.

    1975-01-01

    Shielding, radiation damage, and radiation heating at the planned ISABELLE storage rings were considered. Radiation shielding studies were reviewed and were found to be adequate for present day dosage limits. Radiation damage could be encountered in some extreme cases, but is not expected to limit the performance of the superconducting magnets. Experiments to study the effect of radiation heating on actual magnets are recommended

  2. Pleiotropic effects of incretins

    Directory of Open Access Journals (Sweden)

    Vishal Gupta

    2012-01-01

    Full Text Available Drugs that augment the incretin system [glucagon like peptide (GLP agonists and dipeptidyl peptidase-4 (DPP-4 inhibitors] represent a novel class of anti-hyperglycemic agents that have shown to improve the health and survival of beta-cells (improvement in postprandial hyperglycemia and suppress glucagon (improvement in fasting hyperglycemia. The incretins represent a large family of molecules referred to as the "glucagon superfamily of peptide hormones" of which more than 90% of the physiological effects of incretins are accomplished by GLP-1 7-37 and GLP1 7-36 amide and gastric insulinotropic peptide (GIP. GLP-1 mediates its effects via the GLP-1 receptor, which has a wide tissue distribution [pancreas, lung, heart, vascular smooth muscle cells, endothelial cells, macrophages and monocytes, kidney, gastrointestinal tract (stomach and intestine, central nervous system (neoortex, cerebellum, hypothalamus, hippocampus, brainstem nucleus tractus solitarius and peripheral nervous system]. This would imply that the incretin system has effects outside the pancreas. Over time data has accumulated to suggest that therapies that augment the incretin system has beneficial pleiotrophic effects. The incretins have shown to possess a cardiac-friendly profile, preserve neuronal cells and safeguard from neuronal degeneration, improve hepatic inflammation and hepatosteatosis, improve insulin resistance, promote weight loss and induce satiety. There is growing evidence that they may also be renoprotective promoting wound healing and bone health.

  3. Radiation effects on lymphocytes

    International Nuclear Information System (INIS)

    Roser, B.

    1976-01-01

    This review of the ontogeny of lymphocyte populations concentrates on sites of production, rates of production, and the factors governing the differentiation and longevity of the various lymphocyte pools. The physiology of the lymphocyte pools is described with particular emphasis on recirculation from blood to lymph through lymphoid tissues. The separate routes of recirculation of both thymus-derived and nonthymus-derived lymphocytes and the possible anatomical sites and mechanisms of lymphocyte cooperation are discussed. Radiation effects on lymphocyte populations are divided into two sections. First, the effects of whole-body irradiation on the total lymphocyte pools are discussed including the differential effects of irradiation on T lymphocytes, B lymphocytes, lymphoblasts, and plasma cells. The differential sensitivity of various types of immune response is correlated, where possible, with the differential sensitivity of the lymphocyte types involved. Second, experimental attempts to selectively deplete discrete subpopulations of the total lymphocyte pools, e.g., recirculating cells, are briefly discussed with particular emphasis on studies on the effects of the localization of radionuclides in lymphoid tissue

  4. Poetry Pages. Sound Effects.

    Science.gov (United States)

    Fina, Allan de

    1992-01-01

    Explains how elementary teachers can help students understand onomatopoeia, suggesting that they define onomatopoeia, share examples of it, read poems and have students discuss onomatopoeic words, act out common household sounds, write about sound effects, and create choral readings of onomatopoeic poems. Two appropriate poems are included. (SM)

  5. Radioprotective effect of interferon

    Energy Technology Data Exchange (ETDEWEB)

    Zasukhina, G.

    1984-12-18

    A cycle of experiments performed jointly with associations of the Moscow Engineering Physics Institute reportedly demonstrated that interferons protect human cells cultivated in a test tube against the action of fast neutrons and gamma radiation. Cells treated in advance with interferon not only survived irradiation but were almost totally protected against harmful effects of fast neutrons on the structure of chromosomes, according to the author. She mentions that the laboratory has also been studying effects produced on cells by compounds of heavy metals and other chemical compounds, including ones which cause breaks in the DNA molecule. Interferon's ability to protect cells against effects of chemical compounds has been studied in this connection. Another direction of the laboratory's work is research on interferon's effects on blood cells of persons suffering from certain hereditary diseases in which restorative processes of cells are impaired. The purpose of this is to develop courses of treatment which will not cause irreversible damages to chromosomes, the author explains. Interferon has been found to stimulate the reparation systems of cells in cases of Marfan's syndrome, for example.

  6. The Hawking effect

    International Nuclear Information System (INIS)

    Saffary, T.

    2001-02-01

    The subject of this diploma thesis is the Hawking effect. We study Fredenhagen and Haag's proof of the Hawking radiation in the framework of a semiclassical theory, the quantum field theory in curved spacetime. In particular we give an exact derivation for the short distance behaviour of the two-point function on the Schwarzschild radius

  7. Ensuring effective project management

    International Nuclear Information System (INIS)

    Ward, J.N.

    1980-01-01

    A brief description is given of the organisation methods employed by the Bechtel Power Corporation, in their contract with Mississippi Power and Light Company for the design, construction and procurement activities for the Grand Gulf Nuclear Station. The aim is to ensure effective management, and good communications at all stages of construction, between the project team and the client. (U.K.)

  8. Radiation effects in gases

    International Nuclear Information System (INIS)

    Leonhardt, J.W.

    1985-01-01

    Problems in the studies of radiation effects in gases are discussed. By means of ionization- excitation- and electron-capture yields various applications are characterized: ionization detectors, X-ray detectors, radionuclide battery, and radiation-induced chemical gas-phase reactions. Some new results of basic research in respect to the SO 2 oxidation are discussed. (author)

  9. Effects of pollutant metals

    International Nuclear Information System (INIS)

    Ragan, H.A.

    1983-01-01

    The in vitro cloning efficiency of granulocytic stem cells from mouse bone marrow was completely inhibited or markedly reduced by lead and by materials from shale oil and coal liquefaction processes. Effects of whole body irradiation to syngeneic mice then given DMSO-treated or SRC-injected bone marrow are now being studied

  10. The Kaye effect

    International Nuclear Information System (INIS)

    Binder, J M; Landig, A J

    2009-01-01

    The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for secondary school students. This is our solution to problem number 10, The Kaye effect, as presented in the final round of the 21st IYPT in Trogir, Croatia. The Kaye effect occurs when a thin stream of shampoo or a different adequate non-Newtonian liquid is poured onto a surface. Suddenly, a jet leaves the heap that is formed by the shampoo and begins to 'dance' around the primary jet like a lasso. The phenomenon ends when the 'dancing' jet hits the primary jet and subsequently collapses. We started our investigations based on available literature (Kaye 1963 Nature 197 1001, Versluis et al 2006 J. Stat. Mech., Collyer and Fischer 1976 Nature 261 682). We made experiments with a similar experimental set-up in which we could determine the velocities of both shampoo streams as well as the angle of the 'dancing' stream. From there on, we developed a theoretical model for the energy loss of the jet in the heap. We discovered that the air layer between the jet and the heap is a necessity for the Kaye effect to occur. At this point, our observations differ from the aforementioned literature. This also accounts for the shampoo beam acting as a light guide. Further experiments concerning the viscoelasticity of the shampoo revealed that the elastic property of the shampoo is necessary for the effect to occur.

  11. The Kaye effect

    Energy Technology Data Exchange (ETDEWEB)

    Binder, J M; Landig, A J [Student Research Center Suedwuerttemberg, Gutenbergstrasse 18, 88348 Bad Saulgau (Germany)], E-mail: jan.binder@sfz-bw.de, E-mail: andreas.landig@sfz-bw.de

    2009-11-15

    The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for secondary school students. This is our solution to problem number 10, The Kaye effect, as presented in the final round of the 21st IYPT in Trogir, Croatia. The Kaye effect occurs when a thin stream of shampoo or a different adequate non-Newtonian liquid is poured onto a surface. Suddenly, a jet leaves the heap that is formed by the shampoo and begins to 'dance' around the primary jet like a lasso. The phenomenon ends when the 'dancing' jet hits the primary jet and subsequently collapses. We started our investigations based on available literature (Kaye 1963 Nature 197 1001, Versluis et al 2006 J. Stat. Mech., Collyer and Fischer 1976 Nature 261 682). We made experiments with a similar experimental set-up in which we could determine the velocities of both shampoo streams as well as the angle of the 'dancing' stream. From there on, we developed a theoretical model for the energy loss of the jet in the heap. We discovered that the air layer between the jet and the heap is a necessity for the Kaye effect to occur. At this point, our observations differ from the aforementioned literature. This also accounts for the shampoo beam acting as a light guide. Further experiments concerning the viscoelasticity of the shampoo revealed that the elastic property of the shampoo is necessary for the effect to occur.

  12. Camp's "Disneyland" Effect.

    Science.gov (United States)

    Renville, Gary

    1999-01-01

    Describes the positive mental, physical, and social growth impacts that the camping experience had on the author, and urges camp program evaluation to plan and implement such changes. Sidebar lists steps of effective evaluation: program goals and objectives, goals of evaluation, implementation of evaluation, data analysis, and findings and…

  13. Multimodal news framing effects

    NARCIS (Netherlands)

    Powell, T.E.

    2017-01-01

    Visuals in news media play a vital role in framing citizens’ political preferences. Yet, compared to the written word, visual images are undervalued in political communication research. Using framing theory, this thesis redresses the balance by studying the combined, or multimodal, effects of visual

  14. Marijuana: respiratory tract effects.

    Science.gov (United States)

    Owen, Kelly P; Sutter, Mark E; Albertson, Timothy E

    2014-02-01

    Marijuana is the most commonly used drug of abuse in the USA. It is commonly abused through inhalation and therefore has effects on the lung that are similar to tobacco smoke, including increased cough, sputum production, hyperinflation, and upper lobe emphysematous changes. However, at this time, it does not appear that marijuana smoke contributes to the development of chronic obstructive pulmonary disease. Marijuana can have multiple physiologic effects such as tachycardia, peripheral vasodilatation, behavioral and emotional changes, and possible prolonged cognitive impairment. The carcinogenic effects of marijuana are unclear at this time. Studies are mixed on the ability of marijuana smoke to increase the risk for head and neck squamous cell carcinoma, lung cancer, prostate cancer, and cervical cancer. Some studies show that marijuana is protective for development of malignancy. Marijuana smoke has been shown to have an inhibitory effect on the immune system. Components of cannabis are under investigation as treatment for autoimmune diseases and malignancy. As marijuana becomes legalized in many states for medical and recreational use, other forms of tetrahydrocannabinol (THC) have been developed, such as food products and beverages. As most research on marijuana at this time has been on whole marijuana smoke, rather than THC, it is difficult to determine if the currently available data is applicable to these newer products.

  15. Effects of ionizing radiations

    International Nuclear Information System (INIS)

    Gaussens, G.

    1984-08-01

    After recalling radiation-matter interaction, influence on radiation effects of chemical composition, structure, irradiation atmosphere, dose rate, temperature of organic materials and evolution of electrical, mechanical and physical properties are reviewed. Then behaviour under irradiation of main organic materials: elastomers, thermoplastics, thermosetting plastics, oils and paints are examined. 68 refs [fr

  16. Effects of elevated CO

    NARCIS (Netherlands)

    Xue, Sha; Yang, Xiaomei; Liu, Guobin; Gai, Lingtong; Zhang, Changsheng; Ritsema, Coen J.; Geissen, Violette

    2017-01-01

    Elevated CO2 and drought are key consequences of climate change and affect soil processes and plant growth. This study investigated the effects of elevated CO2 and drought on the microbial biomass and enzymatic activities in the rhizospheres of Bothriochloa ischaemum and

  17. Effectivity and Power

    NARCIS (Netherlands)

    Karos, Dominik; Peters, Hans

    2016-01-01

    We axiomatically develop a class of power indices for effectivity functions, both for the case where the set of alternatives is finite and where it is infinite. Such power indices make it possible to take the issues under consideration into account, in contrast to power indices defined just for

  18. Anomalous Hall effect

    Czech Academy of Sciences Publication Activity Database

    Nagaosa, N.; Sinova, Jairo; Onoda, S.; MacDonald, A. H.; Ong, N. P.

    2010-01-01

    Roč. 82, č. 2 (2010), s. 1539-1592 ISSN 0034-6861 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 51.695, year: 2010

  19. Space Environmental Effects Knowledgebase

    Science.gov (United States)

    Wood, B. E.

    2007-01-01

    This report describes the results of an NRA funded program entitled Space Environmental Effects Knowledgebase that received funding through a NASA NRA (NRA8-31) and was monitored by personnel in the NASA Space Environmental Effects (SEE) Program. The NASA Project number was 02029. The Satellite Contamination and Materials Outgassing Knowledgebase (SCMOK) was created as a part of the earlier NRA8-20. One of the previous tasks and part of the previously developed Knowledgebase was to accumulate data from facilities using QCMs to measure the outgassing data for satellite materials. The main object of this current program was to increase the number of material outgassing datasets from 250 up to approximately 500. As a part of this effort, a round-robin series of materials outgassing measurements program was also executed that allowed comparison of the results for the same materials tested in 10 different test facilities. Other programs tasks included obtaining datasets or information packages for 1) optical effects of contaminants on optical surfaces, thermal radiators, and sensor systems and 2) space environmental effects data and incorporating these data into the already existing NASA/SEE Knowledgebase.

  20. Effects of acid rain

    Energy Technology Data Exchange (ETDEWEB)

    1976-03-01

    The ecological problems that are caused by sulfur pollution in Scandinavia are addressed. Subsequent chemical and physical transformations that the pollutants undergo in the atmosphere are included. The effects of pollutants on soil nutrients, with consequences mainly for forest production, are discussed. Other effects include acidification of lakes and rivers, resulting in decreased fish production. The size of the drop in pH is quite substantial in some of the lakes. The decreased pH has an immediate effect on the change in species composition of fish populations, such as trout and salmon. Efforts to reduce sulfur pollution are discussed. A long term program for the reduction of sulfur in fuel oil has been introduced. At present, there is a ban on the use of oil containing more then 2.5% S (by weight). A further ban on oil containing more than 1% sulfur is in effect in the three major urban areas of Sweden as well as a number of counties. It has been urged by environmental health authorities that in urban pollution control sulfur should be regarded as an indicator of pollutions and not be dealt with as an isolated problem.

  1. Unconscious advertising effects

    NARCIS (Netherlands)

    Moorman, M.; Belch, M.A.; Belch, G.E.

    2011-01-01

    Most traditional advertising effect models are based on the premise that advertising is attended to and processed consciously. However, recent neuroscientific research shows that most information is unconsciously attended to, processed, and stored in memory. The concept of unconscious processing is

  2. Exploring energy rebound effects

    NARCIS (Netherlands)

    Heijs, W.J.M.; Adrians, R.

    2011-01-01

    In the debate on sustainable energy use, one important aspect tends to be systematically overlooked. Sustainability may be increased by developing technological innovations and measures to promote energy conservation, but so-called rebound effects constitute a potential and largely underestimated

  3. Effective magnetic Hamiltonians

    Czech Academy of Sciences Publication Activity Database

    Drchal, Václav; Kudrnovský, Josef; Turek, I.

    2013-01-01

    Roč. 26, č. 5 (2013), s. 1997-2000 ISSN 1557-1939 R&D Projects: GA ČR GA202/09/0775 Institutional support: RVO:68378271 Keywords : effective magnetic Hamiltonian * ab initio * magnetic structure Subject RIV: BE - Theoretical Physics Impact factor: 0.930, year: 2013

  4. Theorising EIA effectiveness

    NARCIS (Netherlands)

    Lyhne, Ivar; Laerhoven, van Frank; Cashmore, Matthew; Runhaar, Hens

    2017-01-01

    Considerable attention has been given to the effectiveness of environmental impact assessment (EIA) since the 1970s. Relatively few research studies, however, have approached EIA as an instrument of environmental governance, and have explored the mechanisms through which EIA influences the

  5. Effective Classroom Management

    Science.gov (United States)

    Mansor, Azlin Norhaini; Eng, Wong Kim; Rasul, Mohamad Sattar; Hamzah, Mohd Izham Mohd; Hamid, Aida Hanim A.

    2012-01-01

    This paper attempts to explore and identify the characteristics of an effective teacher who teaches English as a second language to 10 year old students from different ethnics, various social economic background and multi-level language ability, at a private primary school in Malaysia. The study focused on classroom management using a case study…

  6. Antihypertensive effects of astaxanthin

    Directory of Open Access Journals (Sweden)

    Hiroshi Yoshida

    2008-10-01

    Full Text Available Hidekatsu Yanai1,2, Kumie Ito1,2, Hiroshi Yoshida2,3, Norio Tada1,21Department of Internal Medicine; 2Institute of Clinical Medicine and Research; 3Department of Laboratory Medicine, The Jikei University School of Medicine, Chiba, JapanAbstract: Astaxanthin is a biological antioxidant naturally found in a wide variety of aquatic living organisms, and has shown various pharmacological activities, such as anti-inflammatory and antidiabetic activities. A recent study reported that the administration of astaxanthin induced a significant reduction in blood pressure and delayed the incidence of stroke in stroke-prone spontaneously hypertensive rats, suggesting that astaxanthin also has antihypertensive effect. In a study using aortic rings of spontaneously hypertensive rats, astaxanthin induced a significant reduction of the contractile responses of the aorta to α-adrenergic receptor agonist and angiotensin II, which may contribute to the antihypertensive effect of astaxanthin. In a histopathological study, astaxanthin decreased coronary artery wall thickness compared with the control, indicating the possibility that astaxanthin ameliorates hypertension-induced vascular remodeling. Astaxanthin has anti-inflammatory, antidiabetic, antihypertensive, and antioxidative activities; therefore, we should perform further studies to elucidate an antiatherogenic effect of astaxanthin.Keywords: astaxanthin, antioxidant, antihypertensive effect, atherosclerosis

  7. EFFECTIVE ELECTRONIC TUTORIAL

    Directory of Open Access Journals (Sweden)

    Andrei A. Fedoseev

    2014-01-01

    Full Text Available The article analyzes effective electronic tutorials creation and application based on the theory of pedagogy. Herewith the issues of necessary electronic tutorial functional, ways of the educational process organization with the use of information and communication technologies and the logistics of electronic educational resources are touched upon. 

  8. The weapons effect

    NARCIS (Netherlands)

    Benjamin, Arlin James; Bushman, Brad J.

    In some societies, weapons are plentiful and highly visible. This review examines recent trends in research on the weapons effect, which is the finding that the mere presence of weapons can prime people to behave aggressively. The General Aggression Model provides a theoretical framework to explain

  9. Antioxidant effects of carotenoids

    NARCIS (Netherlands)

    Bast, A.; Haenen, G.R.M.M.; Berg, R. van den; Berg, H. van den

    1998-01-01

    Surprisingly, neither the precise pharmacological effect nor the toxicological profile is usually established for food components. Carotenoids are no exception in this regard. Only limited insight into the pharmacology and toxicology of carotenoids exists. It is known that the antioxidant action of

  10. Occlusion effects, Part I

    DEFF Research Database (Denmark)

    Hansen, Mie Østergaard

    annoyances and the objective measurements were analysed. Persons suffering from tinnitus behaved differently than person without tinnitus. The latter group showed significant relations between the measured occlusion effect, hearing loss and the personal of occlusion. The actual sensation level is also...

  11. Using Media Effectively.

    Science.gov (United States)

    Danzer, Gerald A.; Newman, Mark

    1992-01-01

    Recommends that media presentations can be used effectively in the history classroom as images of reality. Suggests films and television programs and documentaries that can be utilized to show how movies play a role in shaping opinion and changing perceptions. (DK)

  12. The Multiplier Effect.

    Science.gov (United States)

    Flowers, William L., Jr.; Harris, John B.

    1981-01-01

    The multiplier effect is discussed as it applies to the field of continuing education. The authors' main point is that one grant or contract can, and should, be used as the basis for building organizational competencies and capabilities that will secure other funds. (Author/CT)

  13. Cataloging Efficiency and Effectiveness.

    Science.gov (United States)

    McCain, Cheryl; Shorten, Jay

    2002-01-01

    Reports on a survey of academic libraries that was conducted to supplement findings of cost studies by providing measures of efficiency and effectiveness for cataloging departments based on reported productivity, number of staff, task distribution, and quality measures including backlogs, authority control, and database maintenance. Identifies…

  14. Damping Effect of Humans

    DEFF Research Database (Denmark)

    Pedersen, Lars

    2012-01-01

    system and change its dynamic behavior and its dynamic characteristics. When predicting structural vibrations it is not common to account for the passive crowd, but the paper will illustrate effects of the presence of a passive croud on structural behavior. Numerical and experimental results...

  15. Late somatic effects

    International Nuclear Information System (INIS)

    Gilbert, E.S.

    1989-01-01

    Late effects are by definition effects that occur at least one year, and in most cases decades, after the time of exposure. The late effects considered in this chapter are limited to latent cancer incidence and mortality, and benign thyroid disease. A model is provided for estimating risks of late effects resulting from the radiation exposure likely to be received in the event of a nuclear power plant accident. It is assumed that exposure to high-LET radiation would be negligible in such an accident, and thus only risks from low-LET exposure are evaluated. Separate estimates are provided for risks of leukemia, bone cancer, lung cancer, gastrointestinal cancers, thyroid cancer, skin cancer, and the residual group of all other cancers; estimates of leukemia and other cancers due to in utero exposure are also provided. Risks are expressed in absolute terms as the number of cancer deaths (or cases) per million persons exposed to a particular dose. Because the time of death is also important in assessing the impact of an accident, and because the quality of life after the occurrence of cancer will often be reduced, the number of years of life lost and the number of years of life lived after the occurrence of cancer are also estimated

  16. Problems in photoradiation effects

    International Nuclear Information System (INIS)

    Milinchuk, V.K.

    1986-01-01

    This paper discusses the most interesting photoradiation effects observed in recent years and directs attention to problems whose solution has a bearing on progress in photoradiation chemistry, and which also are significant for divisions of modern physical chemistry such as the kinetics and mechanisms of elementary processes in solid organic materials, the radiation resistance of organic materials, and aging in polymers

  17. The Faraday effect revisited

    DEFF Research Database (Denmark)

    Cornean, Horia; Nenciu, Gheorghe

    2009-01-01

    This paper is the second in a series revisiting the (effect of) Faraday rotation. We formulate and prove the thermodynamic limit for the transverse electric conductivity of Bloch electrons, as well as for the Verdet constant. The main mathematical tool is a regularized magnetic and geometric...

  18. Cognitive Effects and Sedation.

    Science.gov (United States)

    Dhingra, Lara; Ahmed, Ebtesam; Shin, Jae; Scharaga, Elyssa; Magun, Maximilian

    2015-10-01

    Cognitive effects and sedation (CES) are prevalent in chronic nonmalignant pain populations receiving long-term opioid therapy and are among the most common reasons patients discontinue opioid use. In this narrative review, we describe the phenomenology, epidemiology, mechanisms, assessment, and management of opioid-related CES. We reviewed the empirical and theoretical literature on CES in opioid-treated populations with chronic pain. Data on long-term opioid therapy (≥ 3 months in duration) in chronic nonmalignant pain patients were sought. The phenomenology of CES includes: inattention, concentration difficulties, memory deficits, psychomotor dysfunction, perceptual distortions, and executive dysfunction and somnolence, sleep disorders, and lethargy. Deficits may be caused by unrelieved pain or opioid therapy alone, or from a combination of these and other factors. Mechanisms include central nervous system effects, for example, direct toxic effects on neurons resulting in decreased consciousness; direct effects on processing and reaction resulting in cognitive or psychomotor impairment, and inhibitory effects on cholinergic activity. Pharmacological management approaches may include opioid dose reduction and rotation or psychostimulant use. Nonpharmacological approaches may include cognitive-behavioral therapy, mindfulness-based stress reduction, acupuncture, exercise, and yoga. The most prevalent CES include: memory deficits (73-81%), sleep disturbance (35-57%), and fatigue (10%). At its most severe, extreme cognitive dysfunction can result in frank delirium and decreased alertness can result in coma. Emotional distress, sleep disorders, and other comorbidities and treatments can worsen CES, particularly among the elderly. Conclusions about the neuropsychological domains affected by opioids are limited due to the heterogeneity of studies and methodological issues. Wiley Periodicals, Inc.

  19. Health Effects of Air Pollution

    Science.gov (United States)

    ... Health effects of air pollution Health effects of air pollution Breathing air that is not clean can hurt ... important to know about the health effects that air pollution can have on you and others. Once you ...

  20. Effects of Medications on Voice

    Science.gov (United States)

    ... ENTCareers Marketplace Find an ENT Doctor Near You Effects of Medications on Voice Effects of Medications on Voice Patient Health Information News ... replacement therapy post-menopause may have a variable effect. An inadequate level of thyroid replacement medication in ...

  1. Regional Healthcare Effectiveness

    Directory of Open Access Journals (Sweden)

    Olga Vladimirovna Kudelina

    2016-03-01

    Full Text Available An evaluation of healthcare systems effectiveness of the regions of the Russian Federation (federal districts was conducted using the Minmax method based on the data available at the United Interdepartmental Statistical Information System. Four groups of components (i.e. availability of resources; use of resources; access to resources and medical effectiveness decomposed into 17 items were analyzed. The resource availability was measured by four indicators, including the provision of doctors, nurses, hospital beds; agencies providing health care to the population. Use of resources was measured by seven indicators: the average hospital stay, days; the average bed occupancy, days; the number of operations per 1 physician surgical; the cost per unit volume of medical care: in outpatient clinics, day hospitals, inpatient and emergency care. Access to the resources was measured by three indicators: the satisfaction of the population by medical care; the capacity of outpatient clinics; the average number of visits to health facility. The medical effectiveness was also measured by three indicators: incidence with the "first-ever diagnosis of malignancy"; life expectancy at birth, years; the number of days of temporary disability. The study of the dynamics of the components and indexes for 2008–2012 allows to indicate a multidirectional influence on the regional healthcare system. In some federal districts (e.g. North Caucasian, the effectiveness decreases due to resource availability, in others (South, North Caucasian — due to the use of resources, in others (Far Eastern, Ural — due to access to resources. It is found that the effectiveness of the healthcare systems of the federal districts differs significantly. In addition, the built matrix proves the variability the of effectiveness (comparison of expenditures and results of healthcare systems of the federal districts of the Russian Federation: the high results can be obtained at high costs

  2. Biological effects of ionizing radiation

    International Nuclear Information System (INIS)

    Heribanova, A.

    1995-01-01

    The basic principles and pathways of effects of ionizing radiation on living organisms and cells are outlined. The following topics are covered: effects of radiation on living matter (direct effects, radical or indirect effects, dual radiation action, and molecular biological theories); effects of radiation on cells and tissues (cell depletion, changes in the cytogenetic information, reparation mechanisms), dose-response relationship (deterministic effects, stochastic effects), and the effects of radiation on man (acute radiation sickness, acute local changes, fetus injuries, non-tumorous late injuries, malignant tumors, genetic changes). (P.A.). 3 tabs., 2 figs., 5 refs

  3. Effects of radiation on man

    International Nuclear Information System (INIS)

    Saunders, P.A.H.

    1981-01-01

    The available evidence on the effects of radiation on man and the predictions that have been made of possible low level effects are reviewed. Data from United Nations Scientific Committee of the Effects of Atomic Radiation (UNSCEAR) and the committee on the Biological Effects of Ionising Radiation (BEIR) is used to illustrate the acute, delayed and hereditary effects of high dose levels. The effects of low dose levels are discussed on the assumption that both somatic and hereditary effects can be predicted on the basis of linear extrapolation from high dose effects. (U.K.)

  4. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media.

    Science.gov (United States)

    Ma, Manman; Xu, Zhenli

    2014-12-28

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  5. Self-consistent field model for strong electrostatic correlations and inhomogeneous dielectric media

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Manman, E-mail: mmm@sjtu.edu.cn; Xu, Zhenli, E-mail: xuzl@sjtu.edu.cn [Department of Mathematics, Institute of Natural Sciences, and MoE Key Laboratory of Scientific and Engineering Computing, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2014-12-28

    Electrostatic correlations and variable permittivity of electrolytes are essential for exploring many chemical and physical properties of interfaces in aqueous solutions. We propose a continuum electrostatic model for the treatment of these effects in the framework of the self-consistent field theory. The model incorporates a space- or field-dependent dielectric permittivity and an excluded ion-size effect for the correlation energy. This results in a self-energy modified Poisson-Nernst-Planck or Poisson-Boltzmann equation together with state equations for the self energy and the dielectric function. We show that the ionic size is of significant importance in predicting a finite self energy for an ion in an inhomogeneous medium. Asymptotic approximation is proposed for the solution of a generalized Debye-Hückel equation, which has been shown to capture the ionic correlation and dielectric self energy. Through simulating ionic distribution surrounding a macroion, the modified self-consistent field model is shown to agree with particle-based Monte Carlo simulations. Numerical results for symmetric and asymmetric electrolytes demonstrate that the model is able to predict the charge inversion at high correlation regime in the presence of multivalent interfacial ions which is beyond the mean-field theory and also show strong effect to double layer structure due to the space- or field-dependent dielectric permittivity.

  6. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.

    1981-01-01

    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  7. Renormalization and effective lagrangians

    International Nuclear Information System (INIS)

    Polchinski, J.

    1984-01-01

    There is a strong intuitive understanding of renormalization, due to Wilson, in terms of the scaling of effective lagrangians. We show that this can be made the basis for a proof of perturbative renormalization. We first study renormalizability in the language of renormalization group flows for a toy renormalization group equation. We then derive an exact renormalization group equation for a four-dimensional lambda PHI 4 theory with a momentum cutoff. We organize the cutoff dependence of the effective lagrangian into relevant and irrelevant parts, and derive a linear equation for the irrelevant part. A lengthy but straightforward argument establishes that the piece identified as irrelevant actually is so in perturbation theory. This implies renormalizability. The method extends immediately to any system in which a momentum-space cutoff can be used, but the principle is more general and should apply for any physical cutoff. Neither Weinberg's theorem nor arguments based on the topology of graphs are needed. (orig.)

  8. Developing Effective Clinical Trainers

    Directory of Open Access Journals (Sweden)

    Kevin Khamarko

    2012-05-01

    Full Text Available Continuing education and training provides a means to improve performance among health care professionals (HCP. Research shows, however, that continuing professional education activities have inconsistent effects on HCP competence, performance, and patient health outcomes. Furthermore, the trainer’s role as a facilitator of knowledge translation (KT has been understudied. To understand how clinical trainers support their trainees in translating what they learned into practice, we conducted 16 in-depth interviews with expert trainers. These interviews yielded a variety of KT-enhancing strategies, including tailoring training activities to their trainees’ needs. In addition, participants recommended trainers familiarize themselves with their trainees’ work environments, be able to identify their knowledge deficits, and devote time to provide trainees with post-training support. Creating an effective training, one that leads to transfer, requires active planning, communication, and command of the training topic by skilled trainers.

  9. Transverse spin effects

    International Nuclear Information System (INIS)

    Ratcliffe, P.G.

    1993-01-01

    A discussion is presented of the role that transverse spin physics can play in providing information on the bound state dynamics in hadronic physics. Care is taken to distinguish between single- and double-spin measurements, each being discussed separately. In the case of single-spin effects it is stressed that as yet no satisfactory explanation has been provided within the framework if perturbative QCD which in fact generally predicts negligible effects. In order to clarify the situation experimental data at yet higher p T are necessary and semi-leptonic data could shed some light on the underlying scattering mechanisms. As regards double-spin correlations, the theoretical picture (although clouded by some ill-informed, often erroneous statements and even recent papers) is rather well understood and what is dearly missing is the experimental study of, for example, g 2 in deep-inelastic scattering. (author). 31 refs

  10. Radiation Effects Research Foundation

    International Nuclear Information System (INIS)

    1979-01-01

    The last day of March 1978 marked the completion of the first 3 years of operation of the Radiation Effects Research Foundation in Hiroshima and Nagasaki. RERF was established on 1 April 1975 as successor to the Atomic Bomb Casualty Commission which had been in continuous operation since 1947. This record of the first 3 years of operation consists of selected reports and other documents prepared in the course of conducting the business of RERF and includes a brief history, a late radiation effects that might be conducted at RERF. The wisdom and thought given to the research program and its operation by the Scientific Council and the Board of Directors is reflected in the minutes of their meetings which are included in the Appendix. (Mori, K.)

  11. [Adverse effects of oxcarbazepine].

    Science.gov (United States)

    Fang, Shu; Gong, Zhi-Cheng

    2015-04-01

    Oxcarbazepine is a new antiepileptic drug. The results of clinical trials suggest that oxcarbazepine is well tolerated and has less drug interactions. It is being used more and more widely in clinical practice, but its adverse effects should not be ignored. The most common adverse effects of oxcarbazepine are usually related to the central nervous system and digestive system, including fatigue, drowsiness, diplopia, dizziness, nausea and vomit. The common skin adverse reaction is rash. Long-term use of oxcarbazepine may also cause hyponatremia. This article reviews the literature from China and overseas about the adverse effets of oxcarbazepine over the last 10 years in order to find information about rational clinical use of oxcarbazepine.

  12. The Creativity Passdown Effect

    DEFF Research Database (Denmark)

    Pries-Heje, Jan

    2015-01-01

    Purpose – The purpose of this paper is to suggest that translating a design theory (DT) into practice (e.g. creating an instance design artifact (IDA)) is hardly straight-forward and requires substantial creativity. Specifically the authors suggest that adopting a DT embodies a creativity passdown...... effect in which the creative thinking of a team of design theorist(s) inherent in DT invokes a creative mind of a team of artifact instance designer(s) in creating an IDA. In this study, the authors empirically investigate the creativity passdown effect through an action case in which a DT (DT nexus...... designer team introducing a previously published DT as a basis for creating an IDA. Findings – The experience in the action case suggests that using a DT in creating an IDA may encourage design thinking, and in certain way increase its power and practical relevance by fostering the creative mind...

  13. Ozone health effects

    International Nuclear Information System (INIS)

    Easterly, C.

    1994-01-01

    Ozone is a principal component of photochemical air pollution endogenous to numerous metropolitan areas. It is primarily formed by the oxidation of NOx in the presence of sunlight and reactive organic compounds. Ozone is a highly active oxidizing agent capable of causing injury to the lung. Lung injury may take the form of irritant effects on the respiratory tract that impair pulmonary function and result in subjective symptoms of respiratory discomfort. These symptoms include, but are not limited to, cough and shortness of breath, and they can limit exercise performance. The effects of ozone observed in humans have been primarily limited to alterations in respiratory function, and a range of respiratory physiological parameters have been measured as a function of ozone exposure in adults and children. These affects have been observed under widely varying (clinical experimental and environmental settings) conditions

  14. Lightning Physics and Effects

    Science.gov (United States)

    Orville, Richard E.

    2004-03-01

    Lightning Physics and Effects is not a lightning book; it is a lightning encyclopedia. Rarely in the history of science has one contribution covered a subject with such depth and thoroughness as to set the enduring standard for years, perhaps even decades, to come. This contribution covers all aspects of lightning, including lightning physics, lightning protection, and the interaction of lightning with a variety of objects and systems as well as the environment. The style of writing is well within the ability of the technical non-expert and anyone interested in lightning and its effects. Potential readers will include physicists; engineers working in the power industry, communications, computer, and aviation industries; atmospheric scientists; geophysicists; meteorologists; atmospheric chemists; foresters; ecologists; physicians working in the area of electrical trauma; and, lastly, architects. This comprehensive reference volume contains over 300 illustrations, 70 tables with quantitative information, and over 6000 reference and bibliography entries.

  15. The QCD Effective String

    International Nuclear Information System (INIS)

    Espriu, D.

    2003-01-01

    QCD can be described in a certain kinematical regime by an effective string theory. This string must couple to background chiral fields in a chirally invariant manner, thus taking into account the true chirally non-invariant QCD vacuum. By requiring conformal symmetry of the string and the unitarity constraint on chiral fields we reconstruct the equations of motion for the latter ones. These provide a consistent background for the propagation of the string. By further requiring locality of the effective action we recover the Lagrangian of non-linear sigma model of pion interactions. The prediction is unambiguous and parameter-free. The estimated chiral structural constants of Gasser and Leutwyler fit very well the phenomenological values. (author)

  16. Electricity Distribution Effectiveness

    Directory of Open Access Journals (Sweden)

    Waldemar Szpyra

    2015-12-01

    Full Text Available This paper discusses the basic concepts of cost accounting in the power industry and selected ways of assessing the effectiveness of electricity distribution. The results of effectiveness analysis of MV/LV distribution transformer replacement are presented, and unit costs of energy transmission through various medium-voltage line types are compared. The calculation results confirm the viability of replacing transformers manufactured before 1975. Replacing transformers manufactured after 1975 – only to reduce energy losses – is not economically justified. Increasing use of a PAS type line for energy transmission in local distribution networks is reasonable. Cabling these networks under the current calculation rules of discounts for excessive power outages is not viable, even in areas particularly exposed to catastrophic wire icing.

  17. Aid Effectiveness on Growth

    DEFF Research Database (Denmark)

    Doucouliagos, Hristos; Paldam, Martin

    The AEL (aid effectiveness literature) is econo¬metric studies of the macroeconomic effects of development aid. It contains about 100 papers of which 68 are reduced form estimates of theeffect of aid on growth in the recipient country. The raw data show that growth is unconnected to aid......, but the AEL has put so much structure on the data that all results possible have emerged. The present meta study considers both the best-set of the 68 papers and the all-set of 543 regressions published. Both sets have a positive average aid-growth elasticity, but it is small and insignificant: The AEL has...... betweenstudies is real. In particular, the aid-growth association is stronger for Asian countries, and the aid-growth association is shown to have been weaker in the 1970s....

  18. Context effects in games

    Directory of Open Access Journals (Sweden)

    Ivo Vlaev

    2007-12-01

    Full Text Available We report an experiment exploring sequential context effects on strategy choices in one-shot Prisoner's Dilemma (PD game. Rapoport and Chammah (1965 have shown that some PDs are cooperative and lead to high cooperation rate, whereas others are uncooperative. Participants played very cooperative and very uncooperative games, against anonymous partners. The order in which these games were played affected their cooperation rate by producing perceptual contrast, which appeared only between the trials, but not between two separate sequences of games. These findings suggest that people may not have stable perceptions of absolute cooperativeness. Instead, they judge the cooperativeness of each fresh game only in relation to the previous game. The observed effects suggest that the principles underlying judgments about highly abstract magnitudes such as cooperativeness may be similar to principles governing the perception of sensory magnitudes.

  19. The effects of Chernobyl

    International Nuclear Information System (INIS)

    Lambert, B.E.

    1987-01-01

    It was concluded that the Chernobyl accident will result in an (undetectable) increase of cancer in the U.K. over the next 40-50 years-probably 400-500 cases occurring, less than half of which would be fatal. Preventive measures which could have been instigated would have had doubtful effects in terms of total health detriment in the population. The overall governmental response was marked by confusion. The need for independent monitoring and assessment, and effective public communication was highlighted by the number of unofficial bodies and 'instant experts' approached for advice and information. There is an obvious need for some consensus about intervention or action levels among European countries. (U.K.)

  20. The weapons effect.

    Science.gov (United States)

    Benjamin, Arlin James; Bushman, Brad J

    2018-02-01

    In some societies, weapons are plentiful and highly visible. This review examines recent trends in research on the weapons effect, which is the finding that the mere presence of weapons can prime people to behave aggressively. The General Aggression Model provides a theoretical framework to explain why the weapons effect occurs. This model postulates that exposure to weapons increases aggressive thoughts and hostile appraisals, thus explaining why weapons facilitate aggressive behavior. Data from meta-analytic reviews are consistent with the General Aggression Model. These findings have important practical as well as theoretical implications. They suggest that the link between weapons and aggression is very strong in semantic memory, and that merely seeing a weapon can make people more aggressive. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effectiveness of medical interventions.

    Science.gov (United States)

    Stegenga, Jacob

    2015-12-01

    To be effective, a medical intervention must improve one's health by targeting a disease. The concept of disease, though, is controversial. Among the leading accounts of disease-naturalism, normativism, hybridism, and eliminativism-I defend a version of hybridism. A hybrid account of disease holds that for a state to be a disease that state must both (i) have a constitutive causal basis and (ii) cause harm. The dual requirement of hybridism entails that a medical intervention, to be deemed effective, must target either the constitutive causal basis of a disease or the harms caused by the disease (or ideally both). This provides a theoretical underpinning to the two principle aims of medical treatment: care and cure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Susceptibility to anchoring effects

    Directory of Open Access Journals (Sweden)

    Todd McElroy

    2007-02-01

    Full Text Available Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously presented anchors on participants' judgments. Our findings indicate that participants high in openness-to-experience were significantly more influenced by anchoring cues relative to participants low in this trait. These findings were consistent across two different types of anchoring tasks providing convergent evidence for our hypothesis.

  3. Measuring marketing effectiveness.

    Science.gov (United States)

    Gluckman, J; Michaelis, T

    1987-09-01

    The most frequent question about the marketing function in hospitals today is, What are we getting for our money? To answer this, marketing directors must convince the board first of the need for marketing, then of marketing's effectiveness. To measure marketing effectiveness, some basic needs are a staff, equipment, cooperation between departments, utilization data, and a research budget. Some steps to be followed include developing a marketing data base--consisting of demographic projections, demand projections, and market share--testing a marketing strategy through experimentation, documenting the expected results and measurement techniques, and calculating the expected return on investments. In dealing with those "impossible-to-measure" cases, such as a physician who is not advertising but finds that a competitor is, a decision tree can help determine whether to advertise and how much to spend by indicating what the return on investment might be.

  4. Radiation effects in semiconductors

    CERN Document Server

    2011-01-01

    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  5. Effective quantum field theories

    International Nuclear Information System (INIS)

    Georgi, H.M.

    1989-01-01

    Certain dimensional parameters play a crucial role in the understanding of weak and strong interactions based on SU(2) x U(1) and SU(3) symmetry group theories and of grand unified theories (GUT's) based on SU(5). These parameters are the confinement scale of quantum chromodynamics and the breaking scales of SU(2) x U(1) and SU(5). The concepts of effective quantum field theories and renormalisability are discussed with reference to the economics and ethics of research. (U.K.)

  6. Effects of low doses

    International Nuclear Information System (INIS)

    Le Guen, B.

    2001-01-01

    Actually, even though it is comfortable for the risk management, the hypothesis of the dose-effect relationship linearity is not confirmed for any model. In particular, in the area of low dose rate delivered by low let emitters. this hypothesis is debated at the light of recent observations, notably these ones relative to the mechanisms leading to genetic instability and induction eventuality of DNA repair. The problem of strong let emitters is still to solve. (N.C.)

  7. Effective Majorana neutrino decay

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Lucia [Instituto de Fisica, Facultad de Ingenieria,Universidad de la Republica, Montevideo (Uruguay); Romero, Ismael; Peressutti, Javier; Sampayo, Oscar A. [Universidad Nacional de Mar del Plata, Departamento de Fisica, Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR) CONICET, UNMDP, Mar del Plata (Argentina)

    2016-08-15

    We study the decay of heavy sterile Majorana neutrinos according to the interactions obtained from an effective general theory. We describe the two- and three-body decays for a wide range of neutrino masses. The results obtained and presented in this work could be useful for the study of the production and detection of these particles in a variety of high energy physics experiments and astrophysical observations. We show in different figures the dominant branching ratios and the total decay width. (orig.)

  8. Radiation Bystander Effects Mechanism

    Directory of Open Access Journals (Sweden)

    Shokohzaman Soleymanifard

    2009-06-01

    Full Text Available Introduction: Radiation Induced Bystander Effect (RIBE which cause radiation effects in non-irradiated cells, has challenged the principle according to which radiation traversal through the nucleus of a cell is necessary for producing biological responses. What is the mechanism of this phenomenon? To have a better understanding of this rather ambiguous concept substantial number of original and reviewed article were carefully examined. Results: Irradiated cells release molecules which can propagate in cell environment and/or transmit through gap junction intercellular communication. These molecules can reach to non-irradiated cells and transmit bystander signals. In many investigations, it has been confirmed that these molecules are growth factors, cytokines, nitric oxide and free radicals like reactive oxygen species (ROS. Transmission of by stander signal to neighboring cells persuades them to produce secondary growth factors which in their turn cause further cell injuries. Some investigators suggest, organelles other than nucleus (mitochondria and cell membrane are the origin of these signals.  There is another opinion which suggests double strand breaks (DSB are not directly generated in bystander cells, rather they are due to smaller damage like single strand breaks which accumulate and end up to DSB. Although bystander mechanisms have not been exactly known, it can be confirmed that multiple mechanisms and various pathways are responsible for this effect. Cell type, radiation type, experimental conditions and end points identify the dominant mechanism. Conclusion: Molecules and pathways which are responsible for RIBE, also cause systemic responses to other non-irradiation stresses. So RIBE is a kind of systemic stress or innate immune responses, which are performed by cell microenvironment. Irradiated cells and their signals are components of microenvironment for creating bystander effects.

  9. Effect of Nanotechnology

    OpenAIRE

    D.Baswaraj; Vasanthi,; Sareddy Deepthi; Mohammad Zainuddin

    2012-01-01

    In this paper, we will put forward the vast effect on nanotechnology in various fields. A basic definition of Nanotechnology is the study manipulation and manufacture of extremely minute machines or devices. The future of technology at times becomes easier to predict. Computers will compute faster, materials will become stronger and medicine will cure more diseases .the technology that works at the nanometer scale of molecules and atoms will be a large part of this future, enabling great impr...

  10. Developmental effects of corruption

    OpenAIRE

    Frøystad, Mona

    2007-01-01

    Traditionally, typical measures of corruption have been broad, composite indices which are often meant to measure overall corruption level in a country. In this thesis I study how different types of corruption can have different effects on development, measured by GDP growth, GDP per capita growth and GDP per capita. Thereby, I wanted to see if some types of corruption could be concluded as more damaging than others. I have discussed and empirically tested the consequences of corruption in pu...

  11. Man and radiation effects

    International Nuclear Information System (INIS)

    Rausch, L.

    1982-01-01

    The book describes the effects of ionizing radiation on man in a simple, popular, detailed and generally valid manner and gives a comprehensive picture of the concepts, elements, principles of function, and perspectives of medical radiobiology. Radiobiology in general is explained, and its application in research on the causes of radiolesions and radiation diseases as well as a radiotherapy and radiation protection is discussed in popular form. (orig./MG) [de

  12. The Leverage Ratchet Effect

    OpenAIRE

    Anat R. Admati; Peter M. DeMarzo; Martin F. Hellwig; Paul Pfleiderer

    2013-01-01

    Shareholder-creditor conflicts can create leverage ratchet effects, resulting in inefficient capital structures. Once debt is in place, shareholders may inefficiently increase leverage but avoid reducing it no matter how beneficial leverage reduction might be to total firm value. We present conditions for an irrelevance result under which shareholders view asset sales, pure recapitalization and asset expansion with new equity as equally undesirable. We then analyze how seniority, asset hetero...

  13. Dark Matter Effective Theory

    DEFF Research Database (Denmark)

    Del Nobile, Eugenio; Sannino, Francesco

    2012-01-01

    We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff...... scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties....

  14. [Neuroprotective effects of curcumin].

    Science.gov (United States)

    Li, Yong; Wang, Pengwen

    2009-12-01

    Traditionally, turmeric has been put to use as a food additive and herbal medicine in Asia. Curcumin is an active principle of the perennial herb curcuma longa (commonly known as turmeric). Recent evidence suggests that curcumin has activities with potential for neuroprotective efficacy, including anti-inflammatory, antioxidant, and antiprotein-aggregate activities. In the current review, we provide the newly evidence for the potential role of curcumin in the neuroprotective effects of neurodegenerative diseases like Alzheimer's disease (AD).

  15. Delegating effectively across cultures

    OpenAIRE

    Sylvie Chevrier; Michaël Viegas-Pires

    2013-01-01

    International audience; This article builds on the contingency approach of global leadership to examine empowerment in a cross-cultural context. Drawing upon an ethnographic research in a French NGO settled in Madagascar, it demonstrates that effective empowerment is not so much a matter of degree -more or less delegation- than a matter of manner. Understanding the cultural representations of role and structure formalization, skill development, collective work and decision-making appeared to ...

  16. Coanda effect in valves

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2017-01-01

    Full Text Available Coanda effect takes place in flow within valves diffuser for certain conditions. The valve plug in half-closed position forms wall-jet, which could be stable or instable, depending on geometry and other conditions. This phenomenon was subject of experimental study using time-resolved PIV technique. For the acquired data analysis the special spatio-temporal methods have been used.

  17. Filter Effectiveness Evaluation

    Science.gov (United States)

    2013-08-01

    synthetic paraffinic kerosene (SPK), as well as Ultra Low Sulfur Diesel (ULSD) treated with mono-olein to simulate the effects of biodiesel . Results...fuel. Sufficient analysis and qualification of filter products is becoming increasingly crucial in ground transportation vehicles to promote the...well as a simulated biodiesel composed of ultra low sulfur diesel (ULSD) and mono-olein. As written in the scope of work, the alternative aviation

  18. Radiation effects in metals

    International Nuclear Information System (INIS)

    Leteurtre Jean.

    1978-01-01

    The current understanding of radiation damage in metals is reviewed, simplifying the actual complexity of the effects by considering some aspects separately. The production of point defects in metals, the primary damage state are first studied. The second part of the lecture is devoted to the evolution of this primary damage state as a function of temperature and dose: the steady state concentration of point defects, the nucleation of secondary defects and their growth are successively considered

  19. Effects and side effects of inspections and accountability in education

    NARCIS (Netherlands)

    de Wolff, I.; Janssens, F.

    2005-01-01

    This paper presents an overview of studies into effects and side effects of control mechanisms in education. We focus on effects and side effects of inspection visits and public performance indicators. A first conclusion is that the studies do not provide us with a clear answer to the question of

  20. Separating Gender Composition Effects from Peer Effects in Education

    Science.gov (United States)

    Jahanshahi, Babak

    2017-01-01

    This paper aims to demonstrate the importance of controlling for endogenous peer effects in estimating the influence of gender peer effects on educational outcomes. Using Manski's linear-in-means model, this paper illustrates that the estimation of gender peer effects is potentially biased in the presence of endogenous peer effect in education.…

  1. Stringy effects in scrambling

    Energy Technology Data Exchange (ETDEWEB)

    Shenker, Stephen H. [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University Stanford, CA (United States); Stanford, Douglas [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University Stanford, CA (United States); School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States)

    2015-05-26

    In (http://dx.doi.org/10.1007/JHEP03(2014)067) we gave a precise holographic calculation of chaos at the scrambling time scale. We studied the influence of a small perturbation, long in the past, on a two-sided correlation function in the thermofield double state. A similar analysis applies to squared commutators and other out-of-time-order one-sided correlators (http://dx.doi.org/10.1007/JHEP12(2014)046, http://dx.doi.org/10.1007/JHEP03(2015)051A). The essential bulk physics is a high energy scattering problem near the horizon of an AdS black hole. The above papers used Einstein gravity to study this problem; in the present paper we consider stringy and Planckian corrections. Elastic stringy corrections play an important role, effectively weakening and smearing out the development of chaos. We discuss their signature in the boundary field theory, commenting on the extension to weak coupling. Inelastic effects, although important for the evolution of the state, leave a parametrically small imprint on the correlators that we study. We briefly discuss ways to diagnose these small corrections, and we propose another correlator where inelastic effects are order one.

  2. Understaning the "funding effect"

    Science.gov (United States)

    Oreskes, N.

    2016-12-01

    There is a long history of industry funding of scientific and engineering research in the USA. Much of this work has been of high quality. Research demonstrates, however, that corporate funding can represent a threat to scientific independence and integrity. Studies show that sponsors' interests can affect research results, particularly when sponsors have a strong interest in a particular research outcome. The effects may occur through the impact of subconscious bias on sampling, study design, data interpretation, and/or reporting of results. Corporate funding can also skew research toward investigating certain questions at the expense of others, downplaying the significance of adverse findings, and/or failing to report adverse results. Gifts can affect behavior, even when they are unrelated to research activities. These impacts that are so substantial that they have a name: "the funding effect."[i] Evidence shows that scientists who strive to be objective and fair-minded may nonetheless fall prey to the funding effect. In many cases, the challenges of corporate gifts and funding can be addressed through education and improved self-awareness, agreements that protect researchers' freedom to publish without sponsor approval, sensible disclosure policies, and reasonable sanctions for failures of disclosure. However, in some cases, it may be appropriate for researchers and scientific societies to decline funding.

  3. Squeezing the Efimov effect

    Science.gov (United States)

    Sandoval, J. H.; Bellotti, F. F.; Yamashita, M. T.; Frederico, T.; Fedorov, D. V.; Jensen, A. S.; Zinner, N. T.

    2018-03-01

    The quantum mechanical three-body problem is a source of continuing interest due to its complexity and not least due to the presence of fascinating solvable cases. The prime example is the Efimov effect where infinitely many bound states of identical bosons can arise at the threshold where the two-body problem has zero binding energy. An important aspect of the Efimov effect is the effect of spatial dimensionality; it has been observed in three dimensional systems, yet it is believed to be impossible in two dimensions. Using modern experimental techniques, it is possible to engineer trap geometry and thus address the intricate nature of quantum few-body physics as function of dimensionality. Here we present a framework for studying the three-body problem as one (continuously) changes the dimensionality of the system all the way from three, through two, and down to a single dimension. This is done by considering the Efimov favorable case of a mass-imbalanced system and with an external confinement provided by a typical experimental case with a (deformed) harmonic trap.

  4. Stringy effects in scrambling

    International Nuclear Information System (INIS)

    Shenker, Stephen H.; Stanford, Douglas

    2015-01-01

    In (http://dx.doi.org/10.1007/JHEP03(2014)067) we gave a precise holographic calculation of chaos at the scrambling time scale. We studied the influence of a small perturbation, long in the past, on a two-sided correlation function in the thermofield double state. A similar analysis applies to squared commutators and other out-of-time-order one-sided correlators (http://dx.doi.org/10.1007/JHEP12(2014)046, http://dx.doi.org/10.1007/JHEP03(2015)051A). The essential bulk physics is a high energy scattering problem near the horizon of an AdS black hole. The above papers used Einstein gravity to study this problem; in the present paper we consider stringy and Planckian corrections. Elastic stringy corrections play an important role, effectively weakening and smearing out the development of chaos. We discuss their signature in the boundary field theory, commenting on the extension to weak coupling. Inelastic effects, although important for the evolution of the state, leave a parametrically small imprint on the correlators that we study. We briefly discuss ways to diagnose these small corrections, and we propose another correlator where inelastic effects are order one.

  5. Inverse Faraday Effect Revisited

    Science.gov (United States)

    Mendonça, J. T.; Ali, S.; Davies, J. R.

    2010-11-01

    The inverse Faraday effect is usually associated with circularly polarized laser beams. However, it was recently shown that it can also occur for linearly polarized radiation [1]. The quasi-static axial magnetic field by a laser beam propagating in plasma can be calculated by considering both the spin and the orbital angular momenta of the laser pulse. A net spin is present when the radiation is circularly polarized and a net orbital angular momentum is present if there is any deviation from perfect rotational symmetry. This orbital angular momentum has recently been discussed in the plasma context [2], and can give an additional contribution to the axial magnetic field, thus enhancing or reducing the inverse Faraday effect. As a result, this effect that is usually attributed to circular polarization can also be excited by linearly polarized radiation, if the incident laser propagates in a Laguerre-Gauss mode carrying a finite amount of orbital angular momentum.[4pt] [1] S. ALi, J.R. Davies and J.T. Mendonca, Phys. Rev. Lett., 105, 035001 (2010).[0pt] [2] J. T. Mendonca, B. Thidé, and H. Then, Phys. Rev. Lett. 102, 185005 (2009).

  6. Nonnutritive effects of glutamine.

    Science.gov (United States)

    Roth, Erich

    2008-10-01

    Glutamine is the most abundant free amino acid of the human body. Besides its role as a constituent of proteins and its importance in amino acid transamination, glutamine has regulatory capacity in immune and cell modulation. Glutamine deprivation reduces proliferation of lymphocytes, influences expression of surface activation markers on lymphocytes and monocytes, affects the production of cytokines, and stimulates apoptosis. Moreover, glutamine administration seems to have a positive effect on glucose metabolism in the state of insulin resistance. Glutamine influences a variety of different molecular pathways. Glutamine stimulates the formation of heat shock protein 70 in monocytes by enhancing the stability of mRNA, influences the redox potential of the cell by enhancing the formation of glutathione, induces cellular anabolic effects by increasing the cell volume, activates mitogen-activated protein kinases, and interacts with particular aminoacyl-transfer RNA synthetases in specific glutamine-sensing metabolism. Glutamine is applied under clinical conditions as an oral, parenteral, or enteral supplement either as the single amino acid or in the form of glutamine-containing dipeptides for preventing mucositis/stomatitis and for preventing glutamine-deficiency in critically ill patients. Because of the high turnover rate of glutamine, even high amounts of glutamine up to a daily administration of 30 g can be given without any important side effects.

  7. The intention interference effect.

    Science.gov (United States)

    Cohen, Anna-Lisa; Kantner, Justin; Dixon, Roger A; Lindsay, D Stephen

    2011-01-01

    Intentions have been shown to be more accessible (e.g., more quickly and accurately recalled) compared to other sorts of to-be-remembered information; a result termed an intention superiority effect (Goschke & Kuhl, 1993). In the current study, we demonstrate an intention interference effect (IIE) in which color-naming performance in a Stroop task was slower for words belonging to an intention that participants had to remember to carry out (Do-the-Task condition) versus an intention that did not have to be executed (Ignore-the-Task condition). In previous work (e.g., Cohen et al., 2005), having a prospective intention in mind was confounded with carrying a memory load. In Experiment 1, we added a digit-retention task to control for effects of cognitive load. In Experiment 2, we eliminated the memory confound in a new way, by comparing intention-related and control words within each trial. Results from both Experiments 1 and 2 revealed an IIE suggesting that interference is very specific to the intention, not just to a memory load.

  8. The real butterfly effect

    International Nuclear Information System (INIS)

    Palmer, T N; Döring, A; Seregin, G

    2014-01-01

    Historical evidence is reviewed to show that what Ed Lorenz meant by the iconic phrase ‘the butterfly effect’ is not at all captured by the notion of sensitive dependence on initial conditions in low-order chaos. Rather, as presented in his 1969 Tellus paper, Lorenz intended the phrase to describe the existence of an absolute finite-time predicability barrier in certain multi-scale fluid systems, implying a breakdown of continuous dependence on initial conditions for large enough forecast lead times. To distinguish from ‘mere’ sensitive dependence, the effect discussed in Lorenz's Tellus paper is referred to as ‘the real butterfly effect’. Theoretical evidence for such a predictability barrier in a fluid described by the three-dimensional Navier–Stokes equations is discussed. Whilst it is still an open question whether the Navier–Stokes equation has this property, evidence from both idealized atmospheric simulators and analysis of operational weather forecasts suggests that the real butterfly effect exists in an asymptotic sense, i.e. for initial-time atmospheric perturbations that are small in scale and amplitude compared with (weather) scales of interest, but still large in scale and amplitude compared with variability in the viscous subrange. Despite this, the real butterfly effect is an intermittent phenomenon in the atmosphere, and its presence can be signalled a priori, and hence mitigated, by ensemble forecast methods. (invited article)

  9. Effects of radiation

    International Nuclear Information System (INIS)

    Masse, R.

    2006-01-01

    The medical consequences of a whole-body irradiation come from the destruction of cells and inflammatory reactions it provokes. The most sensitive organs are the tissues that actively split. The embryo is particularly sensitive, from 200 mSv for the effects on the brain development. The reproduction functions are reached for man from 2000 mSv, the ovary sensitivity is less, the oocytes do not split after the fetus life. For adult the bone marrow outrage leads to the disappearing of blood cells (4000 mSv). The doses from 6000 to 10000 mSv lead the failure of the digestive system and lung. for the upper doses every tissue is reached, particularly by the effects on cells of blood vessels. Important brain dysfunctions appear beyond 10000 mSv. As regards the delayed effects of overexposures the epidemiology brings to light sanitary consequences of the exposure of the population to the ionizing radiations and requires that all the possible factors associated for that purpose are considered. About hereditary effects, it appears that moderate acute radiation exposures of even a relatively large human population must have little impact, in spite of the rate of spontaneous congenital deformations is of the order of 6 %. For the induction of cancers, it is not observed excess for doses lower than 200 mSv for adults and 100 mSv for children (the populations studied are survival people of hiroshima and Nagasaki, patients treated by irradiation, uranium miners, children exposed to radioactive iodine after Chernobylsk accident). To simplify an expression of the risk has been fixed to 5% of induced cancer by Sv for population and 4% by Sv for workers, the different being explained by the demography and the sensitivity of the youngest age groups. As regards the low doses of radiations, a bundle of convergent epidemiological observations notices the absence of effects of the low doses rates. Biological mechanisms, notably of repair are approached, then certain accidents (Goiania

  10. Estimation of morbidity effects

    International Nuclear Information System (INIS)

    Ostro, B.

    1994-01-01

    Many researchers have related exposure to ambient air pollution to respiratory morbidity. To be included in this review and analysis, however, several criteria had to be met. First, a careful study design and a methodology that generated quantitative dose-response estimates were required. Therefore, there was a focus on time-series regression analyses relating daily incidence of morbidity to air pollution in a single city or metropolitan area. Studies that used weekly or monthly average concentrations or that involved particulate measurements in poorly characterized metropolitan areas (e.g., one monitor representing a large region) were not included in this review. Second, studies that minimized confounding ad omitted variables were included. For example, research that compared two cities or regions and characterized them as 'high' and 'low' pollution area were not included because of potential confounding by other factors in the respective areas. Third, concern for the effects of seasonality and weather had to be demonstrated. This could be accomplished by either stratifying and analyzing the data by season, by examining the independent effects of temperature and humidity, and/or by correcting the model for possible autocorrelation. A fourth criterion for study inclusion was that the study had to include a reasonably complete analysis of the data. Such analysis would include an careful exploration of the primary hypothesis as well as possible examination of te robustness and sensitivity of the results to alternative functional forms, specifications, and influential data points. When studies reported the results of these alternative analyses, the quantitative estimates that were judged as most representative of the overall findings were those that were summarized in this paper. Finally, for inclusion in the review of particulate matter, the study had to provide a measure of particle concentration that could be converted into PM10, particulate matter below 10

  11. Effects of increased biofuel utilization

    International Nuclear Information System (INIS)

    Bahr, J.; Blad, B.; Hillring, B.

    1996-01-01

    This report is a compilation of present knowledge regarding the effects of an increased use of biomass fuels. Main areas treated are: Availability of raw materials; Effects on forestry and agriculture; Transportation; Areas of use; Cost and price formation; Emission to the atmosphere, and effect on the climate; and Effect on employment and regional aspects. 29 tabs

  12. Isotope effects on nuclear shielding

    International Nuclear Information System (INIS)

    Hansen, P.E.

    1983-01-01

    This review concentrates upon empirical trends and practical uses of mostly secondary isotope effects, both of the intrinsic and equilibrium types. The text and the tables are arranged in the following fashion. The most 'popular' isotope effect is treated first, deuterium isotope effects on 13 C nuclear shielding, followed by deuterium on 1 H nuclear shieldings, etc. Focus is thus on the isotopes producing the effect rather than on the nuclei suffering the effect. After a brief treatment of each type of isotope effect, general trends are dealt with. Basic trends of intrinsic isotope effects such as additivity, solvent effects, temperature effects, steric effects, substituent effects and hyperconjugation are discussed. Uses of isotope effects for assignment purposes, in stereochemical studies, in hydrogen bonding and in isotopic tracer studies are dealt with. Kinetic studies, especially of phosphates, are frequently performed by utilizing isotope effects. In addition, equilibrium isotope effects are treated in great detail as these are felt to be new and very important and may lead to new uses of isotope effects. Techniques used to obtain isotope effects are briefly surveyed at the end of the chapter. (author)

  13. Cumulative radiation effect

    International Nuclear Information System (INIS)

    Kirk, J.; Cain, O.; Gray, W.M.

    1977-01-01

    Cumulative Radiation Effect (CRE) represents a scale of accumulative sub-tolerance radiation damage, with a unique value of the CRE describing a specific level of radiation effect. Computer calculations have been used to simplify the evaluation of problems associated with the applications of the CRE-system in radiotherapy. In a general appraisal of the applications of computers to the CRE-system, the various problems encountered in clinical radiotherapy have been categorised into those involving the evaluation of a CRE at a point in tissue and those involving the calculation of CRE distributions. As a general guide, the computer techniques adopted at the Glasgow Institute of Radiotherapeutics for the solution of CRE problems are presented, and consist basically of a package of three interactive programs for point CRE calculations and a Fortran program which calculates CRE distributions for iso-effect treatment planning. Many examples are given to demonstrate the applications of these programs, and special emphasis has been laid on the problem of treating a point in tissue with different doses per fraction on alternate treatment days. The wide range of possible clinical applications of the CRE-system has been outlined and described under the categories of routine clinical applications, retrospective and prospective surveys of patient treatment, and experimental and theoretical research. Some of these applications such as the results of surveys and studies of time optimisation of treatment schedules could have far-reaching consequences and lead to significant improvements in treatment and cure rates with the minimum damage to normal tissue. (author)

  14. Telepsychiatry: effectiveness and feasibility

    Directory of Open Access Journals (Sweden)

    Gajaria A

    2015-04-01

    Full Text Available Amy Gajaria,1 David K Conn,1,2 Robert Madan1,2 1Department of Psychiatry, University of Toronto, Toronto, ON, Canada; 2Department of Psychiatry, Baycrest Health Sciences, Toronto, ON, Canada Abstract: Providing psychiatric services by real-time videoconferencing has been increasingly adopted as a method of reaching hard-to-serve populations since the early 1990s. As the field has expanded, a growing body of research has developed investigating both how telepsychiatry compares to in-person psychiatric care and how effectively telepsychiatry can be implemented in routine clinical care. A narrative review was performed to consider the evidence that telepsychiatry is feasible and effective across a variety of patient populations and clinical settings. There is a growing body of evidence investigating the efficacy of telepsychiatry when used for psychiatric assessment and treatment in the adult, child, and geriatric populations. Though studies vary in quality, they generally demonstrate that telepsychiatry is effective across multiple age groups and clinical settings. Telepsychiatry is generally well accepted by patients and clinicians and is feasible to implement, with the suggestion that some patients may actually prefer telepsychiatry to in-person treatment. Issues to consider in the implementation of telepsychiatry services include funding and reimbursement, medico-legal issues when provision crosses legislative boundaries, incorporation into existing health systems, and crosscultural considerations. Future directions for research and practice include a need for higher-quality efficacy studies, consideration of data security, increased attention to low- and middle-income countries, and the introduction of novel technological approaches. Keywords: efficacy, service delivery, telemental health, videoconferencing 

  15. Effectiveness of peritonaeal dialysis

    Directory of Open Access Journals (Sweden)

    Jovanović Nataša

    2005-01-01

    Full Text Available Introduction. In the last few years, an increasing number of patients suffering from terminal renal disease of various leading causes was treated with renal replacement therapy. Peritonaeal dialysis involves an exchange of water and solutes between blood in the peritonaeal capillaries and dialysate in the peritonaeal cavum throughout the peritonaeum. Effective dialysis treatment should provide good quality of life, decrease the number of physical complaints, and bring the incidence of morbidity and mortality closer to the incidence of morbidity and mortality in the healthy population. Aim. The aim of this study was the evaluation of peritonaeal transport characteristics and dialysis effectiveness in 58 patients affected by terminal renal disease who underwent peritonaeal dialysis treatment during August 2003 at the Clinic of Nephrology of the Clinical Centre of Serbia. Method. We examined 30 male and 28 female patients, with an average age of 52 years (range 26 to 78 years. The average duration of peritoneal dialysis treatment was 20 months (ranging from 2 to 66 months, and the end-stage renal failure was caused by different leading disease in our patients. We applied different dialysis modalities: continuous ambulatory peritonaeal dialysis (CAPD with three to five 2- or 3-litre exchanges daily, cyclic peritonaeal dialysis (CCPD, intermittent peritonaeal dialysis (IPD, or automatic peritonaeal dialysis (APD, according to the transport characteristics of the peritonaeal membrane, the residual renal function (RRF, and the clinical status of the patients, in order to perform adequate depuration as suggested by the new international criteria. A peritonaeal equilibrium test (PET was performed according to the new international advice; urea and creatinine clearances (Kt/V and Ccr as well as RRF were calculated using the internationally suggested formulas. Results. Most of our patients received effective dialysis treatment, thanks to the modulation of

  16. Effecting dietary change.

    Science.gov (United States)

    Adamson, Ashley J; Mathers, John C

    2004-11-01

    A world epidemic of diet-related chronic disease is currently being faced. In the UK incidence of obesity alone has tripled in the last 20 years and this trend is predicted to continue. Consensus exists for the urgent need for a change in diet and other lifestyle factors and for the direction and targets for this change. The evidence for how this change can be achieved is less certain. It has been established that disease processes begin in childhood. Recent evidence indicates that dietary habits too are established in childhood but that these habits are amenable to change. While establishing a healthy lifestyle in childhood is paramount, interventions have the potential to promote positive change throughout the life course. Success in reversing current trends in diet-related disease will depend on commitment from legislators, health professionals, industry and individuals, and this collaboration must seek to address not only the food choices of the individual but also the environment that influences such choices. Recent public health policy development in England, if fully supported and implemented, is a positive move towards this goal. Evidence for effective strategies to promote dietary change at the individual level is emerging and three reviews of this evidence are discussed. In addition, three recent dietary intervention studies, in three different settings and with different methods and aims, are presented to illustrate methods of effecting dietary change. Further work is required on what factors influence the eating behaviour and physical activity of individuals. There is a need for further theory-based research on which to develop more effective strategies to enable individuals to adopt healthier lifestyles.

  17. Effects of background radiation

    International Nuclear Information System (INIS)

    Knox, E.G.; Stewart, A.M.; Gilman, E.A.; Kneale, G.W.

    1987-01-01

    The primary objective of this investigation is to measure the relationship between exposure to different levels of background gamma radiation in different parts of the country, and different Relative Risks for leukaemias and cancers in children. The investigation is linked to an earlier analysis of the effects of prenatal medical x-rays upon leukaemia and cancer risk; the prior hypothesis on which the background-study was based, is derived from the earlier results. In a third analysis, the authors attempted to measure varying potency of medical x-rays delivered at different stages of gestation and the results supply a link between the other two estimates. (author)

  18. Environmental Effects of BPA

    Directory of Open Access Journals (Sweden)

    Laura Canesi

    2015-07-01

    Full Text Available Research on bisphenol A (BPA as an environmental contaminant has now major regulatory implications toward the ecosystem health, and hence it is incumbent on scientists to do their research to the highest standards possible, in order that the most appropriate decisions are made to mitigate the impacts to aquatic wildlife. However, the contribution given so far appears rather fragmented. The present overview aims to collect available information on the effects of BPA on aquatic vertebrates and invertebrates to provide a general scenario and to suggest future developments toward more comprehensive approaches useful for aquatic species protection.

  19. Space Charge Effects

    CERN Document Server

    Ferrario, M.; Palumbo, L.

    2014-12-19

    The space charge forces are those generated directly by the charge distribution, with the inclusion of the image charges and currents due to the interaction of the beam with a perfectly conducting smooth pipe. Space charge forces are responsible for several unwanted phenomena related to beam dynamics, such as energy loss, shift of the synchronous phase and frequency , shift of the betatron frequencies, and instabilities. We will discuss in this lecture the main feature of space charge effects in high-energy storage rings as well as in low-energy linacs and transport lines.

  20. The greenhouse effect

    International Nuclear Information System (INIS)

    Choudhury, A.M.

    1990-10-01

    In this paper, the effect of the increase of the temperature of the earth's atmosphere as a consequence of the increase in the CO 2 and other trace gas content has been reviewed. The results of various model studies have been included. There is the frightening prediction that global mean temperature will rise by several degrees with the consequent rise of mean sea level. Model computations also show that in the tropics rainfall will increase whereas in the subtropics and southern mid latitude, rainfall will decrease. If this happens, mankind will be faced with a major disaster in history. Agreement between theory and observations has been discussed. (author). 16 refs, 8 tabs