WorldWideScience

Sample records for spontaneously breaks time-reversal

  1. Spontaneous breaking of time-reversal symmetry in topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Karnaukhov, Igor N., E-mail: karnaui@yahoo.com

    2017-06-21

    Highlights: • Proposed a new approach for description of phase transitions in topological insulators. • Considered the mechanism of spontaneous breaking of time-reversal symmetry in topological insulators. • The Haldane model can be implemented in real compounds of the condensed matter physics. - Abstract: The system of spinless fermions on a hexagonal lattice is studied. We have considered tight-binding model with the hopping integrals between the nearest-neighbor and next-nearest-neighbor lattice sites, that depend on the direction of the link. The links are divided on three types depending on the direction, the hopping integrals are defined by different phases along the links. The energy of the system depends on the phase differences, the solutions for the phases, that correspond to the minimums of the energy, lead to a topological insulator state with the nontrivial Chern numbers. We have analyzed distinct topological states and phase transitions, the behavior of the chiral gapless edge modes, have defined the Chern numbers. The band structure of topological insulator (TI) is calculated, the ground-state phase diagram in the parameter space is obtained. We propose a novel mechanism of realization of TI, when the TI state is result of spontaneous breaking of time-reversal symmetry due to nontrivial stable solutions for the phases that determine the hopping integrals along the links and show that the Haldane model can be implemented in real compounds of the condensed matter physics.

  2. Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

    Science.gov (United States)

    Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

    2014-06-13

    We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

  3. Lateral Casimir-Polder forces by breaking time-reversal symmetry

    Science.gov (United States)

    Oude Weernink, Ricardo R. Q. P. T.; Barcellona, Pablo; Buhmann, Stefan Yoshi

    2018-03-01

    We examine the lateral Casimir-Polder force acting on a circular rotating emitter near a dielectric plane surface. As the circular motion breaks time-reversal symmetry, the spontaneous emission in a direction parallel to the surface is in general anisotropic. We show that a lateral force arises which can be interpreted as a recoil force because of this asymmetric emission. The force is an oscillating function of the distance between the emitter and the surface, and the lossy character of the dielectric strongly influences the results in the near-field regime. The force exhibits also a population-induced dynamics, decaying exponentially with respect to time on time scales of the inverse of the spontaneous decay rate. We propose that this effect could be detected measuring the velocity acquired by the emitter, following different cycles of excitation and spontaneous decay. Our results are expressed in terms of the Green's tensor and can therefore easily be applied to more complex geometries.

  4. Time-reversal symmetry breaking in quantum billiards

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Florian

    2009-01-26

    The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally

  5. Time-reversal symmetry breaking in quantum billiards

    International Nuclear Information System (INIS)

    Schaefer, Florian

    2009-01-01

    The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally

  6. Spontaneous symmetry breaking in curved space-time

    International Nuclear Information System (INIS)

    Toms, D.J.

    1982-01-01

    An approach dealing with some of the complications which arise when studying spontaneous symmetry breaking beyond the tree-graph level in situations where the effective potential may not be used is discussed. These situations include quantum field theory on general curved backgrounds or in flat space-times with non-trivial topologies. Examples discussed are a twisted scalar field in S 1 xR 3 and instabilities in an expanding universe. From these it is seen that the topology and curvature of a space-time may affect the stability of the vacuum state. There can be critical length scales or times beyond which symmetries may be broken or restored in certain cases. These features are not present in Minkowski space-time and so would not show up in the usual types of early universe calculations. (U.K.)

  7. Time in Science: Reversibility vs. Irreversibility

    Science.gov (United States)

    Pomeau, Yves

    To discuss properly the question of irreversibility one needs to make a careful distinction between reversibility of the equations of motion and the choice of the initial conditions. This is also relevant for the rather confuse philosophy of the wave packet reduction in quantum mechanics. The explanation of this reduction requires also to make precise assumptions on what initial data are accessible in our world. Finally I discuss how a given (and long) time record can be shown in an objective way to record an irreversible or reversible process. Or: can a direction of time be derived from its analysis? This leads quite naturally to examine if there is a possible spontaneous breaking of the time reversal symmetry in many body systems, a symmetry breaking that would be put in evidence objectively by looking at certain specific time correlations.

  8. Time-reversal symmetry breaking by ac field: Effect of ...

    Indian Academy of Sciences (India)

    deviate from 2 thus signalling on the time-reversal breaking by the ac field. ... is also the parity effect: the enchancement is only present if either P or Q is even. ... analysis (see figure 1) is possible and the ergodic zero-dimensional approx-.

  9. Crossover driven by time-reversal symmetry breaking in quantum chaos

    International Nuclear Information System (INIS)

    Taniguchi, N.; Hashimoto, A.; Simons, B.D.; Altshuler, B.L.

    1994-01-01

    Parametric correlations of the energy spectra of quantum chaotic systems are presented in the presence of time-reversal symmetry-breaking perturbations. The spectra disperse as a function of two external perturbations, one of which preserves time-reversal symmetry, while the other violates it. Exact analytical expressions for the parametric two-point autocorrelation function of the density of states are derived in the crossover region by means of the supermatrix method. For the orthogonal-unitary crossover, the velocity distribution is determined and shown to deviate from Gaussian. (orig.)

  10. Spontaneous symmetry breaking and its cosmological consequences

    International Nuclear Information System (INIS)

    Kobzarev, I.Yu.

    1975-01-01

    The concept of symmetry and of the spontaneous symmetry breaking are presented in popular form as applied to quantum physics. Though the presence of the spontaneous symmetry breaking is not proved directly for interactions of elementary particles, on considering the hypothesis of its presence as applied to the hot Universe theory a possibility of obtaining rather uncommon cosmological consequences is discussed. In particular, spontaneous symmetry breaking of vacuum and the rather hot Universe lead necessarily to the presence of the domain structure of the Universe with the surfase energy at the domain interface in the form of a real physical object

  11. Group theory of spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Ghaboussi, F.

    1987-01-01

    The connection between the minimality of the Higgs field potential and the maximal little groups of its representation obtained by spontaneous symmetry breaking is analyzed. It is shown that for several representations the lowest minimum of the potential is related to the maximal little group of those representations. Furthermore, a practical necessity criterion is given for the representation of the Higgs field needed for spontaneous symmetry breaking

  12. Spontaneous symmetry breaking in N=3 supergravity

    International Nuclear Information System (INIS)

    Zinov'ev, Yu.M.

    1986-01-01

    The possibility of the spontaneous symmetry breaking without a cosmological term in N=3 supergravity is investigated. A new, dual version of N=3 supergravity - U(3)-supergravity is constructed. Such a theory is shown to admit a spontaneous supersymmetry breaking without a cosmological term and with three arbitrary scales, including partial super-Higgs effect N=3 → N=2 and N=3 → N=1

  13. Spontaneous symmetry breaking, self-trapping, and Josephson oscillations

    CERN Document Server

    2013-01-01

    This volume collects a a number of contributions on spontaneous symmetry breaking. Current studies in this general field are going ahead at a full speed. The book present review chapters which give an overview on the major break throughs of recent years. It covers a number of different physical settings which are introduced when a nonlinearity is added to the underlying symmetric problems and its strength exceeds a certain critical value. The corresponding loss of symmetry, called spontaneous symmetry breaking, alias self-trapping into asymmetric states is extensively discussed in this book.

  14. Dynamical Compactification as a Mechanism of Spontaneous Supersymmetry Breaking

    CERN Document Server

    Dvali, Gia

    1997-01-01

    Supersymmetry breaking and compactification of extra space-time dimensions may have a common dynamical origin if our universe is spontaneously generated in the form of a four-dimensional topological or non-topological defect in higher dimensional space-time. Within such an approach the conventional particles are zero modes trapped in the core of the defect. In many cases solutions of this type spontaneously break all supersymmetries of the original theory, so that the low-energy observer from ``our'' universe inside the core would not detect supersymmetry. Since the extra dimensions are not compact but, rather, inaccessible to low-energy observers, the usual infinite tower of the Kaluza-Klein excitations does not exist. Production of superpartners at the energy scale of SUSY restoration will be accompanied by four-momentum non-conservation. (Depending on the nature of the solution at hand, the non-conservation may either happen above some threshold energy or be continuous). In either case, the door to extra d...

  15. Spontaneous breaking of the BRST symmetry in the ABJM theory

    International Nuclear Information System (INIS)

    Faizal, Mir; Upadhyay, Sudhaker

    2014-01-01

    In this paper, we will analyze the ghost condensation in the ABJM theory. We will perform our analysis in N=1 superspace. We show that in the Delbourgo–Jarvis–Baulieu–Thierry–Mieg gauge the spontaneous breaking of BRST symmetry can occur in the ABJM theory. This spontaneous breaking of BRST symmetry is caused by ghost–anti-ghost condensation. We will also show that in the ABJM theory, the ghost–anti-ghost condensates remain present in the modified abelian gauge. Thus, the spontaneous breaking of BRST symmetry in ABJM theory can even occur in the modified abelian gauge

  16. Strong evidence for spontaneous chiral symmetry breaking in (quenched) QCD

    International Nuclear Information System (INIS)

    Barbour, I.M.; Gibbs, P.; Schierholz, G.; Teper, M.; Gilchrist, J.P.; Schneider, H.

    1983-09-01

    We calculate the chiral condensate for all quark masses using Kogut-Susskind fermions in lattice-regularized quenched QCD. The large volume behaviour of at small quark masses demonstrates that the explicit U(1) chiral symmetry is spontaneously broken. We perform the calculation for β = 5.1 to 5.9 and find very good continuum renormalization group behaviour. We infer that the spontaneous breaking we observe belongs to continuum QCD. This constitutes the first unambiguous demonstration of spontaneous chiral symmetry breaking in continuum quenched QCD. (orig.)

  17. On spontaneous parity breaking in three-dimensional gauge-Higgs systems

    International Nuclear Information System (INIS)

    Ambjoern, J.; Farakos, K.; Shaposhnikov, M.E.

    1991-04-01

    We address the question of spontaneous breaking of parity in three-dimensional euclidian SU(2) gauge-Higgs theory by Monte Carlo simulations. We observe no sign of spontaneous parity breaking in the behaviour of local gauge invariant operators. However, the presence of parity odd terms in the action can induce a phase transition to a parity odd ground state. (orig.)

  18. Spontaneous symmetry breaking in 4-dimensional heterotic string

    International Nuclear Information System (INIS)

    Maharana, J.

    1989-07-01

    The evolution of a 4-dimensional heterotic string is considered in the background of its massless excitations such as graviton, antisymmetric tensor, gauge fields and scalar bosons. The compactified bosonic coordinates are fermionized. The world-sheet supersymmetry requirement enforces Thirring-like four fermion coupling to the background scalar fields. The non-abelian gauge symmetry is exhibited through the Ward identities of the S-matrix elements. The spontaneous symmetry breaking mechanism is exhibited through the broken Ward identities. An effective 4-dimensional action is constructed and the consequence of spontaneous symmetry breaking is envisaged for the effective action. 19 refs

  19. Spontaneous breaking of supersymmetry and gauge invariance in supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Sohnius, M. (European Organization for Nuclear Research, Geneva (Switzerland)); West, P. (King' s Coll., London (UK). Dept. of Mathematics)

    1982-08-09

    Using the new minimal auxillary fields of N = 1 supergravity it is found possible to construct a model of local supersymmetry which spontaneously breaks both supersymmetry and gauge invariance. The status of the cosmological constant resulting from this breaking is discussed.

  20. Minimally doubled fermions and spontaneous chiral symmetry breaking

    Directory of Open Access Journals (Sweden)

    Osmanaj (Zeqirllari Rudina

    2018-01-01

    Full Text Available Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks – Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss – Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.

  1. Minimally doubled fermions and spontaneous chiral symmetry breaking

    Science.gov (United States)

    Osmanaj (Zeqirllari), Rudina; Hyka (Xhako), Dafina

    2018-03-01

    Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks - Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss - Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.

  2. Spontaneous SUSY breaking without R symmetry in supergravity

    Science.gov (United States)

    Maekawa, Nobuhiro; Omura, Yuji; Shigekami, Yoshihiro; Yoshida, Manabu

    2018-03-01

    We discuss spontaneous supersymmetry (SUSY) breaking in a model with an anomalous U (1 )A symmetry. In this model, the size of the each term in the superpotential is controlled by the U (1 )A charge assignment and SUSY is spontaneously broken via the Fayet-Iliopoulos of U (1 )A at the metastable vacuum. In the global SUSY analysis, the gaugino masses become much smaller than the sfermion masses, because an approximate R symmetry appears at the SUSY breaking vacuum. In this paper, we show that gaugino masses can be as large as gravitino mass, taking the supergravity effect into consideration. This is because the R symmetry is not imposed so that the constant term in the superpotential, which is irrelevant to the global SUSY analysis, largely contributes to the soft SUSY breaking terms in the supergravity. As the mediation mechanism, we introduce the contributions of the field not charged under U (1 )A and the moduli field to cancel the anomaly of U (1 )A. We comment on the application of our SUSY breaking scenario to the grand unified theory.

  3. Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schemm, E.R., E-mail: eschemm@alumni.stanford.edu [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Levenson-Falk, E.M. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kapitulnik, A. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Department of Applied Physics, Stanford University, Stanford, CA 94305 (United States); Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2017-04-15

    Highlights: • Polar Kerr effect (PKE) probes broken time-reversal symmetry (TRS) in superconductors. • Absence of PKE below Tc in CeCoIn{sub 5} is consistent with dx2-y2 order parameter symmetry. • PKE in the B phase of the multiphase superconductor UPt3 agrees with an E2u model. • Data on URu2Si2 show broken TRS and additional structure in the superconducting state. - Abstract: The connection between chiral superconductivity and topological order has emerged as an active direction in research as more instances of both have been identified in condensed matter systems. With the notable exception of {sup 3}He-B, all of the known or suspected chiral – that is to say time-reversal symmetry-breaking (TRSB) – superfluids arise in heavy fermion superconductors, although the vast majority of heavy fermion superconductors preserve time-reversal symmetry. Here we review recent experimental efforts to identify TRSB states in heavy fermion systems via measurement of polar Kerr effect, which is a direct consequence of TRSB.

  4. Spontaneous breaking of supersymmetry and gauge invariance in supergravity

    International Nuclear Information System (INIS)

    Sohnius, M.; West, P.

    1982-01-01

    Using the new minimal auxillary fields of N = 1 supergravity it is found possible to construct a model of local supersymmetry which spontaneously breaks both supersymmetry and gauge invariance. The status of the cosmological constant resulting from this breaking is discussed. (orig.)

  5. Spontaneous Symmetry-Breaking in a Network Model for Quadruped Locomotion

    Science.gov (United States)

    Stewart, Ian

    2017-12-01

    Spontaneous symmetry-breaking proves a mechanism for pattern generation in legged locomotion of animals. The basic timing patterns of animal gaits are produced by a network of spinal neurons known as a Central Pattern Generator (CPG). Animal gaits are primarily characterized by phase differences between leg movements in a periodic gait cycle. Many different gaits occur, often having spatial or spatiotemporal symmetries. A natural way to explain gait patterns is to assume that the CPG is symmetric, and to classify the possible symmetry-breaking periodic motions. Pinto and Golubitsky have discussed a four-node model CPG network for biped gaits with ℤ2 × ℤ2 symmetry, classifying the possible periodic states that can arise. A more specific rate model with this structure has been analyzed in detail by Stewart. Here we extend these methods to quadruped gaits, using an eight-node network with ℤ4 × ℤ2 symmetry proposed by Golubitsky and coworkers. We formulate a rate model and calculate how the first steady or Hopf bifurcation depends on its parameters, which represent four connection strengths. The calculations involve a distinction between “real” gaits with one or two phase shifts (pronk, bound, pace, trot) and “complex” gaits with four phase shifts (forward and reverse walk, forward and reverse buck). The former correspond to real eigenvalues of the connection matrix, the latter to complex conjugate pairs. The partition of parameter space according to the first bifurcation, ignoring complex gaits, is described explicitly. The complex gaits introduce further complications, not yet fully understood. All eight gaits can occur as the first bifurcation from a fully synchronous equilibrium, for suitable parameters, and numerical simulations indicate that they can be asymptotically stable.

  6. Unified gauge theories with spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    MacDowell, S.W.

    1975-01-01

    Unified gauge theories with spontaneous symmetry breaking are studied with a view to renormalize quantum field theory. Georgi-Glashow and Weinberg-Salam models to unify weak and electromagnetic interactions are discussed in detail. Gauge theories of strong interactions are also considered [pt

  7. Temperature renormalization group approach to spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Manesis, E.; Sakakibara, S.

    1985-01-01

    We apply renormalization group equations that describe the finite-temperature behavior of Green's functions to investigate thermal properties of spontaneous symmetry breaking. Specifically, in the O(N).O(N) symmetric model we study the change of symmetry breaking patterns with temperature, and show that there always exists the unbroken symmetry phase at high temperature, modifying the naive result of leading order in finite-temperature perturbation theory. (orig.)

  8. Gauged Supergravities and Spontaneous Supersymmetry Breaking from the Double Copy Construction

    Science.gov (United States)

    Chiodaroli, M.; Günaydin, M.; Johansson, H.; Roiban, R.

    2018-04-01

    Supergravities with gauged R symmetry and Minkowski vacua allow for spontaneous supersymmetry breaking and, as such, provide a framework for building supergravity models of phenomenological relevance. In this Letter, we initiate the study of double copy constructions for these supergravities. We argue that, on general grounds, we expect their scattering amplitudes to be described by a double copy of the type (spontaneously broken gauge theory)⊗ (gauge theory with broken supersymmetry). We present a simple realization in which the resulting supergravity has U (1 )R gauge symmetry, spontaneously broken N =2 supersymmetry, and massive gravitini. This is the first instance of a double copy construction of a gauged supergravity and of a theory with spontaneously broken supersymmetry. The construction extends in a straightforward manner to a large family of gauged Yang-Mills-Einstein supergravity theories with or without spontaneous gauge-symmetry breaking.

  9. Spontaneous Lorentz breaking at high energies

    International Nuclear Information System (INIS)

    Cheng, H.-C.; Luty, Markus A.; Mukohyama, Shinji; Thaler, Jesse

    2006-01-01

    Theories that spontaneously break Lorentz invariance also violate diffeomorphism symmetries, implying the existence of extra degrees of freedom and modifications of gravity. In the minimal model ('ghost condensation') with only a single extra degree of freedom at low energies, the scale of Lorentz violation cannot be larger than about M ∼ 100GeV due to an infrared instability in the gravity sector. We show that Lorentz symmetry can be broken at much higher scales in a non-minimal theory with additional degrees of freedom, in particular if Lorentz symmetry is broken by the vacuum expectation value of a vector field. This theory can be constructed by gauging ghost condensation, giving a systematic effective field theory description that allows us to estimate the size of all physical effects. We show that nonlinear effects become important for gravitational fields with strength Φ 1/2 ∼> g, where g is the gauge coupling, and we argue that the nonlinear dynamics is free from singularities. We then analyze the phenomenology of the model, including nonlinear dynamics and velocity-dependent effects. The strongest bounds on the gravitational sector come from either black hole accretion or direction-dependent gravitational forces, and imply that the scale of spontaneous Lorentz breaking is M ∼ 12 GeV, g 2 10 15 GeV). If the Lorentz breaking sector couples directly to matter, there is a spin-dependent inverse-square law force, which has a different angular dependence from the force mediated by the ghost condensate, providing a distinctive signature for this class of models

  10. Spontaneous symmetry breaking in spinor Bose-Einstein condensates

    DEFF Research Database (Denmark)

    Scherer, Manuel; Lücke, Bernd; Peise, Jan

    2013-01-01

    We present an analytical model for the theoretical analysis of spin dynamics and spontaneous symmetry breaking in a spinor Bose-Einstein condensate (BEC). This allows for an excellent intuitive understanding of the processes and provides good quantitative agreement with the experimental results...

  11. Spontaneous symmetry breaking in N = 2 supergravity

    International Nuclear Information System (INIS)

    Zinov'ev, Y.M.

    1987-01-01

    A model describing the interaction of N = 2 supergravity with a vector and a linear multiplet is constructed. The model admits the introduction of spontaneous supersymmetry breaking with two arbitrary scales, one of which can be equal to zero, corresponding to the partial super-Higgs effect (N = 2→N = 1). The cosmological term is automatically equal to zero

  12. Stock market speculation: Spontaneous symmetry breaking of economic valuation

    Science.gov (United States)

    Sornette, Didier

    2000-09-01

    Firm foundation theory estimates a security's firm fundamental value based on four determinants: expected growth rate, expected dividend payout, the market interest rate and the degree of risk. In contrast, other views of decision-making in the stock market, using alternatives such as human psychology and behavior, bounded rationality, agent-based modeling and evolutionary game theory, expound that speculative and crowd behavior of investors may play a major role in shaping market prices. Here, we propose that the two views refer to two classes of companies connected through a "phase transition". Our theory is based on (1) the identification of the fundamental parity symmetry of prices (p→-p), which results from the relative direction of payment flux compared to commodity flux and (2) the observation that a company's risk-adjusted growth rate discounted by the market interest rate behaves as a control parameter for the observable price. We find a critical value of this control parameter at which a spontaneous symmetry-breaking of prices occurs, leading to a spontaneous valuation in absence of earnings, similarly to the emergence of a spontaneous magnetization in Ising models in absence of a magnetic field. The low growth rate phase is described by the firm foundation theory while the large growth rate phase is the regime of speculation and crowd behavior. In practice, while large "finite-time horizon" effects round off the predicted singularities, our symmetry-breaking speculation theory accounts for the apparent over-pricing and the high volatility of fast growing companies on the stock markets.

  13. Effective potential and spontaneous symmetry breaking in the noncommutative φ6 model

    International Nuclear Information System (INIS)

    Barbosa, G.D.

    2004-01-01

    We study the conditions for spontaneous symmetry breaking of the (2+1)-dimensional noncommutative φ 6 model in the small-θ limit. In this regime, considering the model as a cutoff theory, it is reasonable to assume translational invariance as a property of the vacuum state and study the conditions for spontaneous symmetry breaking by an effective potential analysis. An investigation of up to the two-loop level reveals that noncommutative effects can modify drastically the shape of the effective potential. Under reasonable conditions, the nonplanar sector of the theory can become dominant and induce symmetry breaking for values of the mass and coupling constants not reached by the commutative counterpart

  14. Spontaneous symmetry breaking and fermion chirality in higher-dimensional gauge theory

    International Nuclear Information System (INIS)

    Wetterich, C.

    1985-01-01

    The number of chiral fermions may change in the course of spontaneous symmetry breaking. We discuss solutions of a six-dimensional Einstein-Yang-Mills theory based on SO(12). In the resulting effective four-dimensional theory they can be interpreted as spontaneous breaking of a gauge group SO(10) to H=SU(3)sub(C)xSU(2)sub(L)xU(1)sub(R)xU(1)sub(B-L). For all solutions, the fermions which are chiral with respect to H form standard generations. However, the number of generations for the solutions with broken SO(10) may be different compared to the symmetric solutions. All solutions considered here exhibit a local generation group SU(2)sub(G)xU(1)sub(G). For the solutions with broken SO(10) symmetry, the leptons and quarks within one generation transform differently with respect to SU(2)sub(G)xU(1)sub(G). Spontaneous symmetry breaking also modifies the SO(10) relations among Yukawa couplings. All this has important consequences for possible fermion mass relations obtained from higher-dimensional theories. (orig.)

  15. Ward identities of local supersymmetry and spontaneous breaking of extended supergravity

    International Nuclear Information System (INIS)

    Cecotti, S.; Girardello, L.; Porrati, M.

    1985-01-01

    It is a general agreement that any extended supergravity theory, in order to lead to a viable model with acceptable phenomenological implications, should admit spontaneous breaking to N = 1 local supersymmetry in a Minkowski background. It is then important to understand the possible patterns of partial breaking of extended local supersymmetry. These patterns strongly depend on the theory being formulated directly in 4-D or in higher-D. In general, the higher-D theories lead to partial breaking in 4-D anti-de Sitter spaces. Examples are known with partial breaking in flat space. They result respectively from a generalized dimensional reduction of the N = 1 theory in 11-D or from the spontaneous compactification of the 10-D low-energy theory from the superstring theory and of a 6-D Maxwell-Einstein supergravity model. We will comment later on this example. In this paper we will discuss some considerations which apply to theories formulated in 4-D

  16. Is spontaneous breaking of R-parity feasible in minimal low-energy supergravity

    International Nuclear Information System (INIS)

    Gato, B.; Leon, J.; Perez-Mercader, J.; Quiros, M.

    1985-01-01

    Spontaneous violation of lepton number without breaking Lorentz invariance can, in principle, be incorporated in models with softly broken supersymmetry. We study the situation for minimal low-energy supergravity models coming from a GUT (hence not having hierarchy destabilizing light singlets) and where the SU(2)xU(1) breaking is radiative. It is found that for this type of model, R-parity breaking requires either too heavy a top quark for a realistic superpartner spectrum or too light a superpartner spectrum for a realistic top quark, making the spontaneous violation of lepton number in the third generation incompatible with present experimental data. We do not discard the possibility of having it in a fourth, heavier, generation. (orig.)

  17. Spontaneous Symmetry Breaking and Nambu–Goldstone Bosons in Quantum Many-Body Systems

    Directory of Open Access Journals (Sweden)

    Tomáš Brauner

    2010-04-01

    Full Text Available Spontaneous symmetry breaking is a general principle that constitutes the underlying concept of a vast number of physical phenomena ranging from ferromagnetism and superconductivity in condensed matter physics to the Higgs mechanism in the standard model of elementary particles. I focus on manifestations of spontaneously broken symmetries in systems that are not Lorentz invariant, which include both nonrelativistic systems as well as relativistic systems at nonzero density, providing a self-contained review of the properties of spontaneously broken symmetries specific to such theories. Topics covered include: (i Introduction to the mathematics of spontaneous symmetry breaking and the Goldstone theorem. (ii Minimization of Higgs-type potentials for higher-dimensional representations. (iii Counting rules for Nambu–Goldstone bosons and their dispersion relations. (iv Construction of effective Lagrangians. Specific examples in both relativistic and nonrelativistic physics are worked out in detail.

  18. Nonextensive Entropy, Prior PDFs and Spontaneous Symmetry Breaking

    OpenAIRE

    Shafee, Fariel

    2008-01-01

    We show that using nonextensive entropy can lead to spontaneous symmetry breaking when a parameter changes its value from that applicable for a symmetric domain, as in field theory. We give the physical reasons and also show that even for symmetric Dirichlet priors, such a defnition of the entropy and the parameter value can lead to asymmetry when entropy is maximized.

  19. The spontaneous ℤ_2 breaking Twin Higgs

    International Nuclear Information System (INIS)

    Beauchesne, Hugues; Earl, Kevin; Grégoire, Thomas

    2016-01-01

    The Twin Higgs model seeks to address the little hierarchy problem by making the Higgs a pseudo-Goldstone of a global SU(4) symmetry that is spontaneously broken to SU(3). Gauge and Yukawa couplings, which explicitly break SU(4), enjoy a discrete ℤ_2 symmetry that accidentally maintains SU(4) at the quadratic level and therefore keeps the Higgs light. Contrary to most beyond the Standard Model theories, the quadratically divergent corrections to the Higgs mass are cancelled by a mirror sector, which is uncharged under the Standard Model groups. However, the Twin Higgs with an exact ℤ_2 symmetry leads to equal vevs in the Standard Model and mirror sectors, which is phenomenologically unviable. An explicit ℤ_2 breaking potential must then be introduced and tuned against the SU(4) breaking terms to produce a hierarchy of vevs between the two sectors. This leads to a moderate but non-negligible tuning. We propose a model to alleviate this tuning, without the need for an explicit ℤ_2 breaking sector. The model consists of two SU(4) fundamental Higgses, one whose vacuum preserves ℤ_2 and one whose vacuum breaks it. As the interactions between the two Higgses are turned on, the ℤ_2 breaking is transmitted from the broken to the unbroken sector and a small hierarchy of vevs is naturally produced. The presence of an effective tadpole and feedback between the two Higgses lead to a sizable improvement of the tuning. The resulting Higgs boson is naturally very Standard Model like.

  20. Inertial Spontaneous Symmetry Breaking and Quantum Scale Invariance

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Pedro G. [Oxford U.; Hill, Christopher T. [Fermilab; Ross, Graham G. [Oxford U., Theor. Phys.

    2018-01-23

    Weyl invariant theories of scalars and gravity can generate all mass scales spontaneously, initiated by a dynamical process of "inertial spontaneous symmetry breaking" that does not involve a potential. This is dictated by the structure of the Weyl current, $K_\\mu$, and a cosmological phase during which the universe expands and the Einstein-Hilbert effective action is formed. Maintaining exact Weyl invariance in the renormalised quantum theory is straightforward when renormalisation conditions are referred back to the VEV's of fields in the action of the theory, which implies a conserved Weyl current. We do not require scale invariant regulators. We illustrate the computation of a Weyl invariant Coleman-Weinberg potential.

  1. Restoration of supersymmetric Slavnov-Taylor and Ward identities in presence of soft and spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Fischer, I.; Hollik, W.; Roth, M.; Stoeckinger, D.

    2003-12-01

    Supersymmetric Slavnov-Taylor and Ward identities are investigated in presence of soft and spontaneous symmetry breaking. We consider an abelian model where soft supersymmetry breaking yields a mass splitting between electron and selectron and triggers spontaneous symmetry breaking, and we derive corresponding identities that relate the electron and selectron masses with the Yukawa coupling. We demonstrate that the identities are valid in dimensional reduction and invalid in dimensional regularization and compute the necessary symmetry-restoring counterterms. (orig.)

  2. Case report: an electrocardiogram of spontaneous pneumothorax mimicking arm lead reversal.

    Science.gov (United States)

    Wieters, J Scott; Carlin, Joseph P; Morris, Andrew

    2014-05-01

    There are several previously documented findings for electrocardiograms (ECGs) of spontaneous pneumothorax. These findings include axis deviation, T-wave inversion, and right bundle branch block. When an ECG has the arm leads incorrectly placed, the ECG will display right axis deviation and inversion of the P waves in lead I. There have been no previously published ECGs of spontaneous pneumothorax that have shown the same findings as reversal of the limb leads of an ECG. A possible finding of spontaneous pneumothorax is an identical finding to that of an ECG that has been flagged for limb lead reversal. A patient presented in the emergency setting with acute chest pain and shortness of breath caused by a tension pneumothorax. An ECG was administered; findings indicated reversal of the arm leads (right axis deviation and inverted P waves in lead I), but there was no actual limb lead reversal present. ECG findings resolved upon resolution of the pneumothorax. If a patient presents with chest pain and shortness of breath, and the patient's ECG is flagged for limb lead reversal despite being set up correctly, the physician should raise clinical suspicion for a possible spontaneous pneumothorax. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. More on cosmological constraints on spontaneous R-symmetry breaking models

    International Nuclear Information System (INIS)

    Hamada, Yuta; Kobayashi, Tatsuo; Kamada, Kohei; Ecole Polytechnique Federale de Lausanne; Ookouchi, Yutaka

    2013-10-01

    We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the U(1) R breaking scale f a is constrained as f a 12-14 GeV regardless of the value of R-axion mass.

  4. Spontaneous chiral symmetry breaking and effective quark masses in quantum chromodynamics

    International Nuclear Information System (INIS)

    Miransky, V.A.

    1982-01-01

    The ultraviolet asymptotics of the dynamical effective quark mass is determined directly from the equation for the fermion mass function. The indications about the character of the dynamics of the spontaneous chiral symmetry breaking in QCD are obtained

  5. Restoration of supersymmetric Slavnov-Taylor and Ward identities in the presence of soft and spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Fischer, I.; Hollik, W.; Roth, M.; Stoeckinger, D.

    2004-01-01

    Supersymmetric Slavnov-Taylor and Ward identities are investigated in the presence of soft and spontaneous symmetry breaking. We consider an Abelian model where soft supersymmetry breaking yields a mass splitting between electron and selectron and triggers spontaneous symmetry breaking, and we derive the corresponding identities that relate the electron and selectron masses to the Yukawa coupling. We demonstrate that the identities are valid in dimensional reduction and invalid in dimensional regularization and compute the necessary symmetry-restoring counterterms

  6. More on cosmological constraints on spontaneous R-symmetry breaking models

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques; Ookouchi, Yutaka [Kyushu Univ., Fukuoka (Japan). Faculty of Arts and Science

    2013-10-15

    We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the U(1){sub R} breaking scale f{sub a} is constrained as f{sub a}<10{sup 12-14} GeV regardless of the value of R-axion mass.

  7. Dynamics of the universe and spontaneous symmetry breaking

    Science.gov (United States)

    Kazanas, D.

    1980-01-01

    It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.

  8. Noncritical quadrature squeezing through spontaneous polarization symmetry breaking

    OpenAIRE

    Garcia-Ferrer, Ferran V.; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J.; Roldán, Eugenio

    2010-01-01

    We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We consider first type-II frequency-degenerate optical parametric oscillators, but discard them for a number of reasons. Then we propose a four-wave mixing cavity in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity complete noise suppression in a quadrature of the output field occurs, irrespective of ...

  9. Noncritical quadrature squeezing through spontaneous polarization symmetry breaking.

    Science.gov (United States)

    Garcia-Ferrer, Ferran V; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J; Roldán, Eugenio

    2010-07-01

    We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We first consider Type II frequency-degenerate optical parametric oscillators but discard them for a number of reasons. Then we propose a four-wave-mixing cavity, in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity, complete noise suppression in a quadrature of the output field occurs, irrespective of the parameter values.

  10. Spontaneous Symmetry Breaking and Nambu-Goldstone Bosons in Quantum Many-Body Systems

    Czech Academy of Sciences Publication Activity Database

    Brauner, Tomáš

    2010-01-01

    Roč. 2, č. 2 (2010), s. 609-657 ISSN 2073-8994 Institutional support: RVO:61389005 Keywords : spontaneous symmetry breaking * Nambu-Goldstone bosons * effective field theory Subject RIV: BE - Theoretical Physics

  11. Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

    Science.gov (United States)

    Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

    2011-03-01

    In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

  12. Colour break in reverse bicolour daffodils is associated with the presence of Narcissus mosaic virus

    Directory of Open Access Journals (Sweden)

    Davies Kevin M

    2011-08-01

    Full Text Available Abstract Background Daffodils (Narcissus pseudonarcissus are one of the world's most popular ornamentals. They also provide a scientific model for studying the carotenoid pigments responsible for their yellow and orange flower colours. In reverse bicolour daffodils, the yellow flower trumpet fades to white with age. The flowers of this type of daffodil are particularly prone to colour break whereby, upon opening, the yellow colour of the perianth is observed to be 'broken' into patches of white. This colour break symptom is characteristic of potyviral infections in other ornamentals such as tulips whose colour break is due to alterations in the presence of anthocyanins. However, reverse bicolour flowers displaying colour break show no other virus-like symptoms such as leaf mottling or plant stunting, leading some to argue that the carotenoid-based colour breaking in reverse bicolour flowers may not be caused by virus infection. Results Although potyviruses have been reported to cause colour break in other flower species, enzyme-linked-immunoassays with an antibody specific to the potyviral family showed that potyviruses were not responsible for the occurrence of colour break in reverse bicolour daffodils. Colour break in this type of daffodil was clearly associated with the presence of large quantities of rod-shaped viral particles of lengths 502-580 nm in tepals. Sap from flowers displaying colour break caused red necrotic lesions on Gomphrena globosa, suggesting the presence of potexvirus. Red necrotic lesions were not observed in this indicator plant when sap from reverse bicolour flowers not showing colour break was used. The reverse transcriptase polymerase reactions using degenerate primers to carla-, potex- and poty-viruses linked viral RNA with colour break and sequencing of the amplified products indicated that the potexvirus Narcissisus mosaic virus was the predominant virus associated with the occurrence of the colour break

  13. Spontaneous symmetry breaking of (1+1)-dimensional φ4 theory in light-front field theory

    International Nuclear Information System (INIS)

    Bender, C.M.; Pinsky, S.; van de Sande, B.

    1993-01-01

    We study spontaneous symmetry breaking in (1+1)-dimensional φ 4 theory using the light-front formulation of field theory. Since the physical vacuum is always the same as the perturbative vacuum in light-front field theory the fields must develop a vacuum expectation value through the zero-mode components of the field. We solve the nonlinear operator equation for the zero mode in the one-mode approximation. We find that spontaneous symmetry breaking occurs at λ critical =4π(3+ √3 )μ 2 , which is consistent with the value λ critical =54.27μ 2 obtained in the equal-time theory. We calculate the vacuum expectation value as a function of the coupling constant in the broken phase both numerically and analytically using the δ expansion. We find two equivalent broken phases. Finally we show that the energy levels of the system have the expected behavior for the broken phase

  14. Spontaneous symmetry breaking and self-consistent equations for the free-energy

    International Nuclear Information System (INIS)

    Lovesey, S.W.

    1980-03-01

    A variational procedure for the free-energy is used to derive self-consistent equations that allow for spontaneous symmetry breaking. For an N-component phi 4 -model the equations are identical to those obtained by summing all loops to order 1/N. (author)

  15. Noncritical generation of nonclassical frequency combs via spontaneous rotational symmetry breaking

    Science.gov (United States)

    Navarrete-Benlloch, Carlos; Patera, Giuseppe; de Valcárcel, Germán J.

    2017-10-01

    Synchronously pumped optical parametric oscillators (SPOPOs) are optical cavities driven by mode-locked lasers, and containing a nonlinear crystal capable of down-converting a frequency comb to lower frequencies. SPOPOs have received a lot of attention lately because their intrinsic multimode nature makes them compact sources of quantum correlated light with promising applications in modern quantum information technologies. In this work we show that SPOPOs are also capable of accessing the challenging and interesting regime where spontaneous symmetry breaking confers strong nonclassical properties to the emitted light, which has eluded experimental observation so far. Apart from opening the possibility of studying experimentally this elusive regime of dissipative phase transitions, our predictions will have a practical impact, since we show that spontaneous symmetry breaking provides a specific spatiotemporal mode with large quadrature squeezing for any value of the system parameters, turning SPOPOs into robust sources of highly nonclassical light above threshold.

  16. Infrared aspects of spontaneous symmetry breaking of gauge theories in two and three dimensions

    International Nuclear Information System (INIS)

    Cho, H.T.

    1987-01-01

    The spontaneous chiral symmetry breaking in SU(N) quantum chromodynamics (QCD) in two dimensions is investigated by calculating the order parameter , where psi is the fermion in the theory, in the authors approximation. In the chiral limit, where the mass of the fermion m → O, is found to be non-zero both in the finite N and N → infinity cases. This implies that chiral symmetry is spontaneously broken by infrared effects in all these cases. The Wilson loop expectation value is calculated for again SU(N) QCD in two dimensions, without fermions. In two dimensions, the Coulomb potential is linear, and thus confining. Under the authors approximation, the area law of the Wilson loop is indeed obtained as expected, for all values of N; in addition, the N-dependent polynomial multiplying the Wilson exponential is also obtained. In quantum electrodynamics (QED) in three dimensions there is a possibility of spontaneous breaking of parity. The authors consider this possibility by studying and the photon propagator. It is found that in the limit m → O, is zero and the photon has a zero mass pole. Therefore, there is no sign of spontaneous parity violation in (QED) in three dimensions induced by infrared effects, in contrast to the positive result of chiral symmetry breaking in two dimensions

  17. Cosmological constraints on spontaneous R-symmetry breaking models

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research and Dept. of Physics

    2012-11-15

    We study general constraints on spontaneous R-symmetry breaking models coming from the cosmological effects of the pseudo Nambu-Goldstone bosons, R-axions. They are substantially produced in the early Universe and may cause several cosmological problems. We focus on relatively long-lived R-axions and find that in a wide range of parameter space, models are severely constrained. In particular, R-axions with mass less than 1 MeV are generally ruled out for relatively high reheating temperature, T{sub R}>10 GeV.

  18. Spontaneous chiral symmetry breaking in early molecular networks

    Directory of Open Access Journals (Sweden)

    Markovitch Omer

    2010-05-01

    Full Text Available Abstract Background An important facet of early biological evolution is the selection of chiral enantiomers for molecules such as amino acids and sugars. The origin of this symmetry breaking is a long-standing question in molecular evolution. Previous models addressing this question include particular kinetic properties such as autocatalysis or negative cross catalysis. Results We propose here a more general kinetic formalism for early enantioselection, based on our previously described Graded Autocatalysis Replication Domain (GARD model for prebiotic evolution in molecular assemblies. This model is adapted here to the case of chiral molecules by applying symmetry constraints to mutual molecular recognition within the assembly. The ensuing dynamics shows spontaneous chiral symmetry breaking, with transitions towards stationary compositional states (composomes enriched with one of the two enantiomers for some of the constituent molecule types. Furthermore, one or the other of the two antipodal compositional states of the assembly also shows time-dependent selection. Conclusion It follows that chiral selection may be an emergent consequence of early catalytic molecular networks rather than a prerequisite for the initiation of primeval life processes. Elaborations of this model could help explain the prevalent chiral homogeneity in present-day living cells. Reviewers This article was reviewed by Boris Rubinstein (nominated by Arcady Mushegian, Arcady Mushegian, Meir Lahav (nominated by Yitzhak Pilpel and Sergei Maslov.

  19. Reformulation od spontaneous symmetry breaking and the Weinberg-Salam model

    International Nuclear Information System (INIS)

    Rawat, A.S.; Rawat, S.; Negi, O.P.S.

    1999-01-01

    Spontaneous symmetry breaking and the Weinberg-Salam model have been reformulated in terms of quaternion-valued field variables. The quaternion-valued scalar Lagrangian reduces to four different field equations associated with the scalar quartet of a quaternion field φ φ 0 +e 1φ1 +e 2φ2 +e 3φ3 . It has been shown that the quaternion gauge group SO(4) is spontaneously broken to two gauge groups of SU(2) non Abelian gauge fields. The Weinberg-Salam model of electroweak interaction has been extensively studied to enlarge the gauge group structure SU(2) L xSU(2) R xU(1)

  20. Spontaneous symmetry breaking in local gauge quantum field theory; the Higgs mechanism

    International Nuclear Information System (INIS)

    Strocchi, F.

    1977-01-01

    Spontaneous symmetry breakings in indefinite metric quantum field theories are analyzed and a generalization of the Goldstone theorem is proved. The case of local gauge quantum field theories is discussed in detail and a characterization is given of the occurrence of the Higgs mechanism versus the Goldstone mechanism. The Higgs phenomenon is explained on general grounds without the introduction of the so-called Higgs fields. The basic property is the relation between the local internal symmetry group and the local group of gauge transformations of the second kind. Spontaneous symmetry breaking of c-number gauge transformations of the second kind is shown to always occur if there are charged local fields. The implications about the absence of mass gap in the Wightman functions and the occurrence of massless particles associated with the unbroken generators in the Higgs phenomenon are discussed. (orig.) [de

  1. Incoherent transport for phases that spontaneously break translations

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P.; Griffin, Tom; Ziogas, Vaios

    2018-04-01

    We consider phases of matter at finite charge density which spontaneously break spatial translations. Without taking a hydrodynamic limit we identify a boost invariant incoherent current operator. We also derive expressions for the small frequency behaviour of the thermoelectric conductivities generalising those that have been derived in a translationally invariant context. Within holographic constructions we show that the DC conductivity for the incoherent current can be obtained from a solution to a Stokes flow for an auxiliary fluid on the black hole horizon combined with specific thermodynamic quantities associated with the equilibrium black hole solutions.

  2. Vacuum solutions of a gravity model with vector-induced spontaneous Lorentz symmetry breaking

    International Nuclear Information System (INIS)

    Bertolami, O.; Paramos, J.

    2005-01-01

    We study the vacuum solutions of a gravity model where Lorentz symmetry is spontaneously broken once a vector field acquires a vacuum expectation value. Results are presented for the purely radial Lorentz symmetry breaking (LSB), radial/temporal LSB and axial/temporal LSB. The purely radial LSB result corresponds to new black hole solutions. When possible, parametrized post-Newtonian parameters are computed and observational boundaries used to constrain the Lorentz symmetry breaking scale

  3. Spontaneous symmetry breaking due to the trade-off between attractive and repulsive couplings.

    Science.gov (United States)

    Sathiyadevi, K; Karthiga, S; Chandrasekar, V K; Senthilkumar, D V; Lakshmanan, M

    2017-04-01

    Spontaneous symmetry breaking is an important phenomenon observed in various fields including physics and biology. In this connection, we here show that the trade-off between attractive and repulsive couplings can induce spontaneous symmetry breaking in a homogeneous system of coupled oscillators. With a simple model of a system of two coupled Stuart-Landau oscillators, we demonstrate how the tendency of attractive coupling in inducing in-phase synchronized (IPS) oscillations and the tendency of repulsive coupling in inducing out-of-phase synchronized oscillations compete with each other and give rise to symmetry breaking oscillatory states and interesting multistabilities. Further, we provide explicit expressions for synchronized and antisynchronized oscillatory states as well as the so called oscillation death (OD) state and study their stability. If the Hopf bifurcation parameter (λ) is greater than the natural frequency (ω) of the system, the attractive coupling favors the emergence of an antisymmetric OD state via a Hopf bifurcation whereas the repulsive coupling favors the emergence of a similar state through a saddle-node bifurcation. We show that an increase in the repulsive coupling not only destabilizes the IPS state but also facilitates the reentrance of the IPS state.

  4. The flight of the bumblebee: solutions from a vector-induced spontaneous Lorentz symmetry breaking model

    International Nuclear Information System (INIS)

    Bertolami, Orfeu; Paramos, Jorge

    2006-01-01

    The vacuum solutions arising from a spontaneous breaking of Lorentz symmetry due to the acquisition of a vacuum expectation value by a vector field are derived. These include the purely radial Lorentz symmetry breaking (LSB), radial/temporal LSB and axial/temporal LSB scenarios. It is found that the purely radial LSB case gives rise to new black hole solutions. Whenever possible. Parametrized Post-Newtonian (PPN) parameters are computed and compared to observational bounds, in order to constrain the Lorentz symmetry breaking scale

  5. Macroscopic influence on the spontaneous symmetry breaking in quantum field

    International Nuclear Information System (INIS)

    Kirzhnitz, D.A.

    1977-01-01

    Major results of investigations concerning macroscopic influence (heating, compression, external field and current) on elementary particle systems with spontaneous symmetry breaking are briefly reviewed. The study of this problem has been stimulated by recent progress in the unified renormalizable theory of elementary particles. Typically it appears that at some values of external parameters a phase transition with symmetry restoration takes place. There exists a profound and far going analogy with phase transition in many-body physics especially with superconductivity phenomenon. Some applications to cosmology are also considered

  6. Spontaneous symmetry breaking, quantization of the electric charge and the anomalies

    International Nuclear Information System (INIS)

    Abbas, Afsar

    1990-01-01

    Cancellation of anomalies and on ensuring that fermions are massive, one obtains quantization of the electric charge, which is shown to be independent of the hypercharge quantum number of the Higgs doublet in the Standard Model. Ignorance of this fact can lead to pitfalls. It is shown that contrary to the popular belief, charge quantization is not a consequence of the anomalies but that in addition spontaneous symmetry breaking is essential. (author)

  7. Bogoliubov condensation of gluons and spontaneous gauge symmetry breaking in QCD

    International Nuclear Information System (INIS)

    Pervushin, V.N.; Roepke, G.; Volkov, M.K.; Blaschke, D.; Pavel, H.P.; Litvin, A.

    1995-08-01

    The ''squeezed'' representation of commutation relations for gluon fields in QCD is formulated as the mathematical tool for the description of the gluon condensate. We first consider λφ 4 theory and show that the ''squeezed'' Bogoliubov condensate can lead to the spontaneous appearance of a mass. Using the ''squeezed'' representation, we show that in the non-Abelian theory spontaneous gauge symmetry breaking (SGSB) and the appearance of a constituent mass of gluons can be described. We construct a projector onto the oscillator - like variables, for which the ''squeezed'' representation is valid, by using the formal solution of the Gauss equation instead of fixing a gauge. We discuss the effects of the SGSB and present as an application of the approach the calculation of the gluon mass from the difference of the η' and the η - meson masses. (author). 27 refs

  8. Relativistic Hydrodynamics of Color-Flavor Locking Phase with Spontaneous Symmetry Breaking

    Institute of Scientific and Technical Information of China (English)

    ZHANG Sun; WANG Fan

    2004-01-01

    We study the hydrodynamics of color-flavor locking phase of three flavors of light quarks in high density QCD with spontaneous symmetry breaking. The basic hydrodynamic equations are presented based on the Poisson bracket method and the Goldstone phonon and the thermo phonon are compared. The dissipative equations are constructed in the frame of the first-order theory and all the transport coefficients are also defined, which could be looked on as the general case including the Landau's theory and the Eckart's theory

  9. A time-reversal invariant topological phase at the surface of a 3D topological insulator

    International Nuclear Information System (INIS)

    Bonderson, Parsa; Nayak, Chetan; Qi, Xiao-Liang

    2013-01-01

    A 3D fermionic topological insulator has a gapless Dirac surface state protected by time-reversal symmetry and charge conservation symmetry. The surface state can be gapped by introducing ferromagnetism to break time-reversal symmetry, introducing superconductivity to break charge conservation, or entering a topological phase. In this paper, we construct a minimal gapped topological phase that preserves both time-reversal and charge conservation symmetries and supports Ising-type non-Abelian anyons. This phase can be understood heuristically as emerging from a surface s-wave superconducting state via the condensation of eight-vortex composites. The topological phase inherits vortices supporting Majorana zero modes from the surface superconducting state. However, since it is time-reversal invariant, the surface topological phase is a distinct phase from the Ising topological phase, which can be viewed as a quantum-disordered spin-polarized p x + ip y superconductor. We discuss the anyon model of this topological phase and the manner in which time-reversal symmetry is realized in it. We also study the interfaces between the topological state and other surface gapped phases. (paper)

  10. The role of DNA double-strand breaks in spontaneous homologous recombination in S. cerevisiae

    DEFF Research Database (Denmark)

    Lettier, Gaëlle; Feng, Q.; Mayolo, A.A. de

    2006-01-01

    of meiosis and result from the induction of a large number of DNA double-strand breaks (DSBs). By analogy, it is generally believed that the rare spontaneous mitotic HR events are due to repair of DNA DSBs that accidentally occur during mitotic growth. Here we provide the first direct evidence that most...

  11. Quark Yukawa pattern from spontaneous breaking of flavour SU(3) 3

    Science.gov (United States)

    Nardi, Enrico

    2015-10-01

    A SU(3)Q × SU(3)u × SU(3)d invariant scalar potential breaking spontaneously the quark flavour symmetry can explain the Standard Model flavour puzzle. The approximate alignment in flavour space of the vacuum expectation values of the up and down 'Yukawa fields' results as a dynamical effect. The observed quark mixing angles, the weak CP violating phase, and hierarchical quark masses can be all reproduced at the cost of introducing additional (auxiliary) scalar multiplets, but without the need of introducing hierarchical parameters.

  12. Penrose limit, spontaneous symmetry breaking, and holography in a pp-wave background

    International Nuclear Information System (INIS)

    Das, Sumit R.; Gomez, Cesar; Rey, Soo-Jong

    2002-01-01

    We argue that the gauge theory dual to the type IIB string theory in a ten-dimensional pp-wave background resides on a Euclidean subspace spanning four of the eight transverse coordinates. We then show that the evolution of the string along one of the light cone directions in the bulk is identifiable as the RG flow of the gauge theory, a relation facilitating the 'holography' of the pp-wave background. The 'holography' reorganizes the dual gauge theory into theories defined over Hilbert subspaces of fixed R charge. The reorganization breaks the SO(4,2)xSO(6) symmetry to a maximal subgroup SO(4)xSO(4) spontaneously. We argue that the low-energy string modes may be regarded as Goldstone modes resulting from such a symmetry breaking pattern

  13. Fermion Systems in Discrete Space-Time Exemplifying the Spontaneous Generation of a Causal Structure

    Science.gov (United States)

    Diethert, A.; Finster, F.; Schiefeneder, D.

    As toy models for space-time at the Planck scale, we consider examples of fermion systems in discrete space-time which are composed of one or two particles defined on two up to nine space-time points. We study the self-organization of the particles as described by a variational principle both analytically and numerically. We find an effect of spontaneous symmetry breaking which leads to the emergence of a discrete causal structure.

  14. The complex Langevin analysis of spontaneous symmetry breaking induced by complex fermion determinant

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Yuta [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nishimura, Jun [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Graduate University for Advanced Studies (SOKENDAI),1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2016-12-05

    In many interesting physical systems, the determinant which appears from integrating out fermions becomes complex, and its phase plays a crucial role in the determination of the vacuum. An example of this is QCD at low temperature and high density, where various exotic fermion condensates are conjectured to form. Another example is the Euclidean version of the type IIB matrix model for 10d superstring theory, where spontaneous breaking of the SO(10) rotational symmetry down to SO(4) is expected to occur. When one applies the complex Langevin method to these systems, one encounters the singular-drift problem associated with the appearance of nearly zero eigenvalues of the Dirac operator. Here we propose to avoid this problem by deforming the action with a fermion bilinear term. The results for the original system are obtained by extrapolations with respect to the deformation parameter. We demonstrate the power of this approach by applying it to a simple matrix model, in which spontaneous symmetry breaking from SO(4) to SO(2) is expected to occur due to the phase of the complex fermion determinant. Unlike previous work based on a reweighting-type method, we are able to determine the true vacuum by calculating the order parameters, which agree with the prediction by the Gaussian expansion method.

  15. Zurek–Kibble Symmetry Breaking Process in Superconducting Rings; Spontaneous Fluxon Formation in Annular Josephson Tunnel Junctions

    DEFF Research Database (Denmark)

    Aarøe, Morten; Monaco, Roberto; Dmitriev, P

    2007-01-01

    We report on new investigations of spontaneous symmetry breaking in non-adiabatic phase transitions. This Zurek-Kibble (ZK) process is mimicked in solid state systems by trapping of magnetic flux quanta, fluxons, in a long annular Josephson tunnel junction quenched through the normal-superconducting...

  16. Spontaneous breaking of N=2 to N=1 in rigid and local supersymmetric theories

    CERN Document Server

    Ferrara, Sergio; Porrati, Massimo

    1996-01-01

    We analyze the relation between rigid and local supersymmetric N=2 field theories, when half of the supersymmetries are spontaneously broken. In particular, we show that the recently found partial supersymmety breaking induced by electric and magnetic Fayet-Iliopoulos terms in rigid theories can be obtained by a suitable flat limit of previously constructed N=2 supergravity models with partial super-Higgs in the observable sector.

  17. Spontaneous symmetry breaking of (1+1)-dimensional φ4 theory in light-front field theory. II

    International Nuclear Information System (INIS)

    Pinsky, S.S.; van de Sande, B.

    1994-01-01

    We discuss spontaneous symmetry breaking of (1+1)-dimensional φ 4 theory in light-front field theory using a Tamm-Dancoff truncation. We show that, even though light-front field theory has a simple vacuum state which is an eigenstate of the full Hamiltonian, the field can develop a nonzero vacuum expectation value. This occurs because the zero mode of the field must satisfy an operator-valued constraint equation. In the context of (1+1)-dimensional φ 4 theory we present solutions to the constraint equation using a Tamm-Dancoff truncation to a finite number of particles and modes. We study the behavior of the zero mode as a function of coupling and Fock space truncation. The zero mode introduces new interactions into the Hamiltonian which breaks the Z 2 symmetry of the theory when the coupling is stronger than the critical coupling. We investigate the energy spectrum in the symmetric and broken phases, show that the theory does not break down in the vicinity of the critical coupling, and discuss the connection to perturbation theory. Finally, we study the spectrum of the field φ and show that, in the broken phase, the field is localized away from φ=0 as one would expect from equal-time calculations. We explicitly show that tunneling occurs

  18. Study of spontaneously broken conformal symmetry in curved space-times

    International Nuclear Information System (INIS)

    Janson, M.M.

    1977-05-01

    Spontaneous breakdown of Weyl invariance (local scale invariance) in a conformally-invariant extension of a gauge model for weak and electromagnetic interactions is considered. The existence of an asymmetric vacuum for the Higgs field, phi, is seen to depend on the space-time structure via the Gursey-Penrose term, approximately phi + phi R, in the action. (R denotes the scalar curvature.) The effects of a prescribed space-time structure on spontaneously broken Weyl invariance is investigated. In a cosmological space-time, it is found that initially, in the primordial fireball, the symmetry must hold exactly. Spontaneous symmetry breaking (SSB) develops as the universe expands and cools. Consequences of this model include a dependence of G/sub F/, the effective weak interaction coupling strength, on ''cosmic time.'' It is seen to decrease monotonically; in the present epoch (G/sub F//G/sub F/)/sub TODAY/ approximately less than 10 -10 (year) -1 . The effects of the Schwarzschild geometry on SSB are explored. In the interior of a neutron star the Higgs vacuum expectation value, and consequently G/sub F/, is found to have a radial dependence. The magnitude of this variation does not warrant revision of present models of neutron star structures. Another perspective on the problem considered a theory of gravitation (conformal relativity) to be incorporated in the conformally invariant gauge model of weak and electromagnetic interactions. If SSB develops, the vacuum gravitational field equations are the Einstein field equations with a cosmological constant. The stability of the asymmetric vacuum solution is investigated to ascertain whether SSB can occur

  19. Spontaneous symmetry breaking of the BRST symmetry in presence of the Gribov horizon: Renormalizability

    International Nuclear Information System (INIS)

    Capri, Marcio; Justo, Igor; Guimaraes, Marcelo; Sorella, Silvio; Dudal, David; Palhares, Leticia

    2013-01-01

    Full text: In recent years much attention has been devoted to the study of the issue of the Gribov copies and of its relevance for confinement in Yang-Mills theories. The existence of the Gribov copies is a general feature of the gauge-fixing quantization procedure, being related to the impossibility of finding a local gauge condition which picks up only one gauge configuration for each gauge orbit. As it has been shown by Gribov and Zwanziger, a partial solution of the Gribov problem in the Landau gauge can be achieved by restricting the domain of integration in the functional Euclidean integral to the first Gribov horizon. Among the various open aspects of the Gribov-Zwanziger framework, the issue of the BRST symmetry is a source of continuous investigations. In a recent work, we have been able to obtain an equivalent formulation of the Gribov-Zwanziger action which displays an exact BRST symmetry which turns out to be spontaneously broken by the restriction of the domain of integration to the Gribov horizon. In particular, the BRST operator retains the important property of being nilpotent. Moreover, it has also been shown that the Goldstone mode associated to the spontaneous breaking of the BRST symmetry is completely decoupled. The aim of the present work is that of fills up a gap not addressed in the previous work, namely, the renormalizability to all orders of the spontaneous symmetry breaking formulation of the Gribov-Zwanziger theory. As we shall see, the action obtained enjoys a large set of Ward identities which enables to prove that it is, in fact, multiplicatively renormalizable to all orders. (author)

  20. Chains of benzenes with lithium-atom adsorption: Vibrations and spontaneous symmetry breaking

    Science.gov (United States)

    Ortiz, Yenni P.; Stegmann, Thomas; Klein, Douglas J.; Seligman, Thomas H.

    2017-09-01

    We study effects of different configurations of adsorbates on the vibrational modes as well as symmetries of polyacenes and poly-p-phenylenes focusing on lithium atom adsorption. We found that the spectra of the vibrational modes distinguish the different configurations. For more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essentially followed by the adsorbate. On poly-p-phenylenes we found that lithium adsorption reduces and often eliminates the torsion between rings thus increasing symmetry. There is spontaneous symmetry breaking in poly-p-phenylenes due to double adsorption of lithium atoms on alternating rings.

  1. Constraints on a parity-even/time-reversal-odd interaction

    International Nuclear Information System (INIS)

    Oers, Willem T.H. van

    2000-01-01

    Time-Reversal-Invariance non-conservation has for the first time been unequivocally demonstrated in a direct measurement, one of the results of the CPLEAR experiment. What is the situation then with regard to time-reversal-invariance non-conservation in systems other than the neutral kaon system? Two classes of tests of time-reversal-invariance need to be distinguished: the first one deals with parity violating (P-odd)/time-reversal-invariance non-conserving (T-odd) interactions, while the second one deals with P-even/T-odd interactions (assuming CPT conservation this implies C-conjugation non-conservation). Limits on a P-odd/T-odd interaction follow from measurements of the electric dipole moment of the neutron. This in turn provides a limit on a P-odd/T-odd pion-nucleon coupling constant which is 10 -4 times the weak interaction strength. Limits on a P-even/T-odd interaction are much less stringent. The better constraint stems also from the measurement of the electric dipole moment of the neutron. Of all the other tests, measurements of charge-symmetry breaking in neutron-proton elastic scattering provide the next better constraint. The latter experiments were performed at TRIUMF (at 477 and 347 MeV) and at IUCF (at 183 MeV). Weak decay experiments (the transverse polarization of the muon in K + →π 0 μ + ν μ and the transverse polarization of the positrons in polarized muon decay) have the potential to provide comparable or possibly better constraints

  2. Charged tensor matter fields and Lorentz symmetry violation via spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Colatto, L.P.; Penna, A.L.A.; Santos, W.C.

    2003-10-01

    We consider a model with a charged vector field along with a Cremmer-Scherk-Kalb-Ramond (CSKR) matter field coupled to a U(1) gauge potential. We obtain a natural Lorentz symmetry violation due to the local U(1) spontaneous symmetry breaking mechanism triggered by the imaginary part of the vector matter. The choice of the unitary gauge leads to the decoupling of the gauge-Kr sector from the Higgs-Kr sector. The excitation spectrum is carefully analyzed and the physical modes are identified. We propose an identification of the neutral massive spin-1 Higgs-like field with the massive Z' boson of the so-called mirror matter models. (author)

  3. Time-reversal breaking and spin transport induced by magnetic impurities in a 2D topological insulator

    International Nuclear Information System (INIS)

    Derakhshan, V; Ketabi, S A; Moghaddam, A G

    2016-01-01

    We employed the formalism of bond currents, expressed in terms of non-equilibrium Green’s function to obtain the local currents and transport features of zigzag silicene ribbon in the presence of magnetic impurity. When only intrinsic and Rashba spin–orbit interactions are present, silicene behaves as a two-dimensional topological insulator with gapless edge states. But in the presence of finite intrinsic spin–orbit interaction, the edge states start to penetrate into the bulk of the sample by increasing Rashba interaction strength. The exchange interaction induced by local impurities breaks the time-reversal symmetry of the gapless edge states and influences the topological properties strongly. Subsequently, the singularity of partial Berry curvature disappears and the silicene nanoribbon becomes a trivial insulator. On the other hand, when the concentration of the magnetic impurities is low, the edge currents are not affected significantly. In this case, when the exchange field lies in the x – y plane, the spin mixing around magnetic impurity is more profound rather than the case in which the exchange field is directed along the z -axis. Nevertheless, when the exchange field of magnetic impurities is placed in the x – y plane, a spin-polarized conductance is observed. The resulting conductance polarization can be tuned by the concentration of the impurities and even completely polarized spin transport is achievable. (paper)

  4. Light-front quantized field theory (an introduction): spontaneous symmetry breaking. Phase transition in φ4 theory

    International Nuclear Information System (INIS)

    Srivastava, Prem P.

    1994-01-01

    The Dirac procedure is used to construct the Hamiltonian formulation of the scalar field theory on the light-front. The theory is quantized and the mechanism of the spontaneous symmetry breaking in the front form and the instant form dynamics are compared. The phase transition in (φ 4 )2 theory is also discussed and found to be of the second order. (author). 36 refs

  5. Time reversed Lamb wave for damage detection in a stiffened aluminum plate

    International Nuclear Information System (INIS)

    Bijudas, C R; Mitra, M; Mujumdar, P M

    2013-01-01

    According to the concept of time reversibility of the Lamb wave, in the absence of damage, a Lamb wave signal can be reconstructed at the transmitter location if a time reversed signal is sent back from the receiver location. This property is used for baseline-free damage detection, where the presence of damage breaks down the time reversibility and the mismatch between the reconstructed and the input signal is inferred as the presence of damage. This paper presents an experimental and a simulation study of baseline-free damage detection in a stiffened aluminum plate by time reversed Lamb wave (TRLW). In this study, single Lamb wave mode (A 0 ) is generated and sensed using piezoelectric (PZT) transducers through specific transducer placement and amplitude tuning. Different stiffening configurations such as plane and T-stiffeners are considered. Damage cases of disbonding of stiffeners from the base plate, and vertical and embedded cracks in the stiffened plate, are studied. The results show that TRLW based schemes can efficiently identify the presence of damage in a stiffened plate. (paper)

  6. Spontaneous mirror left-right symmetry breaking for leptogenesis parametrized by Majorana neutrino mass matrix

    Science.gov (United States)

    Gu, Pei-Hong

    2017-10-01

    We introduce a mirror copy of the ordinary fermions and Higgs scalars for embedding the SU(2) L × U(1) Y electroweak gauge symmetry into an SU(2) L × SU(2) R × U(1) B-L left-right gauge symmetry. We then show the spontaneous left-right symmetry breaking can automatically break the parity symmetry motivated by solving the strong CP problem. Through the SU(2) R gauge interactions, a mirror Majorana neutrino can decay into a mirror charged lepton and two mirror quarks. Consequently we can obtain a lepton asymmetry stored in the mirror charged leptons. The Yukawa couplings of the mirror and ordinary charged fermions to a dark matter scalar then can transfer the mirror lepton asymmetry to an ordinary lepton asymmetry which provides a solution to the cosmic baryon asymmetry in association with the SU(2) L sphaleron processes. In this scenario, the baryon asymmetry can be well described by the neutrino mass matrix up to an overall factor.

  7. Truncation effects in the functional renormalization group study of spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Defenu, N.; Mati, P.; Márián, I.G.; Nándori, I.; Trombettoni, A.

    2015-01-01

    We study the occurrence of spontaneous symmetry breaking (SSB) for O(N) models using functional renormalization group techniques. We show that even the local potential approximation (LPA) when treated exactly is sufficient to give qualitatively correct results for systems with continuous symmetry, in agreement with the Mermin-Wagner theorem and its extension to systems with fractional dimensions. For general N (including the Ising model N=1) we study the solutions of the LPA equations for various truncations around the zero field using a finite number of terms (and different regulators), showing that SSB always occurs even where it should not. The SSB is signalled by Wilson-Fisher fixed points which for any truncation are shown to stay on the line defined by vanishing mass beta functions.

  8. Spontaneously broken abelian gauge invariant supersymmetric model

    International Nuclear Information System (INIS)

    Mainland, G.B.; Tanaka, K.

    A model is presented that is invariant under an Abelian gauge transformation and a modified supersymmetry transformation. This model is broken spontaneously, and the interplay between symmetry breaking, Goldstone particles, and mass breaking is studied. In the present model, spontaneously breaking the Abelian symmetry of the vacuum restores the invariance of the vacuum under a modified supersymmetry transformation. (U.S.)

  9. Entanglement entropy of a three-spin-interacting spin chain with a time-reversal-breaking impurity at one boundary

    Science.gov (United States)

    Nag, Tanay; Rajak, Atanu

    2018-04-01

    We investigate the effect of a time-reversal-breaking impurity term (of strength λd) on both the equilibrium and nonequilibrium critical properties of entanglement entropy (EE) in a three-spin-interacting transverse Ising model, which can be mapped to a p -wave superconducting chain with next-nearest-neighbor hopping and interaction. Importantly, we find that the logarithmic scaling of the EE with block size remains unaffected by the application of the impurity term, although, the coefficient (i.e., central charge) varies logarithmically with the impurity strength for a lower range of λd and eventually saturates with an exponential damping factor [˜exp(-λd) ] for the phase boundaries shared with the phase containing two Majorana edge modes. On the other hand, it receives a linear correction in term of λd for an another phase boundary. Finally, we focus to study the effect of the impurity in the time evolution of the EE for the critical quenching case where the impurity term is applied only to the final Hamiltonian. Interestingly, it has been shown that for all the phase boundaries, contrary to the equilibrium case, the saturation value of the EE increases logarithmically with the strength of impurity in a certain regime of λd and finally, for higher values of λd, it increases very slowly dictated by an exponential damping factor. The impurity-induced behavior of EE might bear some deep underlying connection to thermalization.

  10. Quantum break-time of de Sitter

    Energy Technology Data Exchange (ETDEWEB)

    Dvali, Gia; Gómez, César; Zell, Sebastian, E-mail: georgi.dvali@physik.uni-muenchen.de, E-mail: cesar.gomez@uam.es, E-mail: sebastian.zell@campus.lmu.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 München (Germany)

    2017-06-01

    The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S -matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/ N -effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N . We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10{sup 100} years old in its entire classical history.

  11. Quantum break-time of de Sitter

    Science.gov (United States)

    Dvali, Gia; Gómez, César; Zell, Sebastian

    2017-06-01

    The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S-matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/N-effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N. We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10100 years old in its entire classical history.

  12. Trex2 enables spontaneous sister chromatid exchanges without facilitating DNA double-strand break repair.

    Science.gov (United States)

    Dumitrache, Lavinia C; Hu, Lingchuan; Son, Mi Young; Li, Han; Wesevich, Austin; Scully, Ralph; Stark, Jeremy; Hasty, Paul

    2011-08-01

    Trex2 is a 3' → 5' exonuclease that removes 3'-mismatched sequences in a biochemical assay; however, its biological function remains unclear. To address biology we previously generated trex2(null) mouse embryonic stem (ES) cells and expressed in these cells wild-type human TREX2 cDNA (Trex2(hTX2)) or cDNA with a single-amino-acid change in the catalytic domain (Trex2(H188A)) or in the DNA-binding domain (Trex2(R167A)). We found the trex2(null) and Trex2(H188A) cells exhibited spontaneous broken chromosomes and trex2(null) cells exhibited spontaneous chromosomal rearrangements. We also found ectopically expressed human TREX2 was active at the 3' ends of I-SceI-induced chromosomal double-strand breaks (DSBs). Therefore, we hypothesized Trex2 participates in DNA DSB repair by modifying 3' ends. This may be especially important for ends with damaged nucleotides. Here we present data that are unexpected and prompt a new model. We found Trex2-altered cells (null, H188A, and R167A) were not hypersensitive to camptothecin, a type-1 topoisomerase inhibitor that induces DSBs at replication forks. In addition, Trex2-altered cells were not hypersensitive to γ-radiation, an agent that causes DSBs throughout the cell cycle. This observation held true even in cells compromised for one of the two major DSB repair pathways: homology-directed repair (HDR) or nonhomologous end joining (NHEJ). Trex2 deletion also enhanced repair of an I-SceI-induced DSB by both HDR and NHEJ without affecting pathway choice. Interestingly, however, trex2(null) cells exhibited reduced spontaneous sister chromatid exchanges (SCEs) but this was not due to a defect in HDR-mediated crossing over. Therefore, reduced spontaneous SCE could be a manifestation of the same defect that caused spontaneous broken chromosomes and spontaneous chromosomal rearrangements. These unexpected data suggest Trex2 does not enable DSB repair and prompt a new model that posits Trex2 suppresses the formation of broken

  13. BOOK REVIEW: Symmetry Breaking

    Science.gov (United States)

    Ryder, L. H.

    2005-11-01

    One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would

  14. Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Devastato, Agostino, E-mail: agostino.devastato@na.infn.it; Martinetti, Pierre, E-mail: martinetti@dima.unige.it [Università di Napoli Federico II, Dipartimento di Fisica (Italy)

    2017-03-15

    Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.

  15. Light-front quantized field theory: (an introduction). Spontaneous symmetry breaking. Phase transition in φ4 theory

    International Nuclear Information System (INIS)

    Srivastava, P.P.

    1993-01-01

    The field theory quantized on the light-front is compared with the conventional equal-time quantized theory. The arguments based on the micro causality principle would imply that the light-front field theory may become nonlocal with respect to the longitudinal coordinate even though the corresponding equal-time formulation is local. This is found to be the case for the scalar theory. The conventional instant form theory is sometimes required to be constrained by invoking external physical considerations; the analogous conditions seem to be already built in the theory on the light-front. In spite of the different mechanisms of the spontaneous symmetry breaking in the two forms of dynamics they result in the same physical content. The phase transition in (φ 4 ) 2 theory is also discussed. The symmetric vacuum state for vanishingly small couplings is found to turn into an unstable symmetric one when the coupling is increased and may result in a phase transition of the second order in contrast to the first order transition concluded from the usual variational methods. (author)

  16. Spontaneous quasi single helicity regimes in EXTRAP T2R reversed-field pinch

    Science.gov (United States)

    Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Menmuir, S.; Cecconello, M.

    2007-11-01

    In recent years, good progress toward a better understanding and control of the plasma performance in reversed-field pinch devices has been made. These improvements consist both of the discovery of spontaneous plasma regimes, termed the quasi single helicity (QSH) regime, in which part of the plasma core is no longer stochastic, and of the development of techniques for active control of plasma instabilities. In this paper, a systematic study of spontaneous QSH in the EXTRAP T2R device [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] is presented. In this device, QSH states can occur spontaneously and it is associated with magnetic and thermal structures. A statistical analysis to determine the most favorable experimental conditions to have a transition to the QSH regime will be presented. The results described here are useful to understand the underlying properties of QSH regimes in view of future applications of the QSH active control in EXTRAP T2R; they are also important to have a comparison with the QSH studied in other devices.

  17. Constraints of a parity-conserving/time-reversal-non-conserving interaction

    International Nuclear Information System (INIS)

    Oers, Willem T.H. van

    2002-01-01

    Time-Reversal-Invariance non-conservation has for the first time been unequivocally demonstrated in a direct measurement at CPLEAR. One then can ask the question: What about tests of time-reversal-invariance in systems other than the kaon system? Tests of time-reversal-invariance can be distinguished as belonging to two classes: the first one deals with time-reversal-invariance-non-conserving (T-odd)/parity violating (P-odd) interactions, while the second one deals with T-odd/P-even interactions (assuming CPT conservation this implies C-conjugation non-conservation). Limits on a T-odd/P-odd interaction follow from measurements of the electric dipole moment of the neutron ( -26 e.cm [95% C.L.]). It provides a limit on a T-odd/P-odd pion-nucleon coupling constant which is less than 10 -4 times the weak interaction strength. Experimental limits on a T-odd/P-even interaction are much less stringent. Following the standard approach of describing the nucleon-nucleon interaction in terms of meson exchanges, it can be shown that only charged ρ-meson exchange and A 1 -meson exchange can lead to a T-odd/P-even interaction. The better constraints stem from measurements of the electric dipole moment of the neutron and from measurements of charge-symmetry breaking in neutron-proton elastic scattering. The latter experiments were executed at TRIUMF (497 and 347 MeV) and at IUCF (183 MeV). All other experiments, like detailed balance experiments, polarization - analyzing power difference determinations, and five-fold correlation experiments with polarized incident nucleons and aligned nuclear targets, have been shown to be at least an order to magnitude less sensitive. Is there room for further experimentation?

  18. Spontaneous symmetry breaking, and strings defects in hypercomplex gauge field theories

    Energy Technology Data Exchange (ETDEWEB)

    Cartas-Fuentevilla, R. [Universidad Autonoma de Puebla, Instituto de Fisica, Puebla, Pue. (Mexico); Meza-Aldama, O. [Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, Pue. (Mexico)

    2016-02-15

    Inspired by the appearance of split-complex structures in the dimensional reduction of string theory, and in the theories emerging as byproducts, we study the hypercomplex formulation of Abelian gauge field theories by incorporating a new complex unit to the usual complex one. The hypercomplex version of the traditional Mexican hat potential associated with the U(1) gauge field theory, corresponds to a hybrid potential with two real components, and with U(1) x SO(1,1) as symmetry group. Each component corresponds to a deformation of the hat potential, with the appearance of a new degenerate vacuum. Hypercomplex electrodynamics will show novel properties, such as spontaneous symmetry breaking scenarios with running masses for the vectorial and scalar Higgs fields, and such as Aharonov-Bohm type strings defects as exact solutions; these topological defects may be detected only by quantum interference of charged particles through gauge invariant loop integrals. In a particular limit, the hyperbolic electrodynamics does not admit topological defects associated with continuous symmetries. (orig.)

  19. Chiral polarization scale of QCD vacuum and spontaneous chiral symmetry breaking

    International Nuclear Information System (INIS)

    Alexandru, Andrei; Horv, Ivan

    2013-01-01

    It has recently been found that dynamics of pure glue QCD supports the low energy band of Dirac modes with local chiral properties qualitatively different from that of a bulk: while bulk modes suppress chirality relative to statistical independence between left and right, the band modes enhance it. The width of such chirally polarized zone – chiral polarization scale bigwedge ch – has been shown to be finite in the continuum limit at fixed physical volume. Here we present evidence that bigwedge ch remains non-zero also in the infinite volume, and is therefore a dynamical scale in the theory. Our experiments in N f = 2+1 QCD support the proposition that the same holds in the massless limit, connecting bigwedge ch to spontaneous chiral symmetry breaking. In addition, our results suggest that thermal agitation in quenched QCD destroys both chiral polarization and condensation of Dirac modes at the same temperature T ch > T c .

  20. Reversible Holmes' tremor due to spontaneous intracranial hypotension.

    Science.gov (United States)

    Iyer, Rajesh Shankar; Wattamwar, Pandurang; Thomas, Bejoy

    2017-07-27

    Holmes' tremor is a low-frequency hand tremor and has varying amplitude at different phases of motion. It is usually unilateral and does not respond satisfactorily to drugs and thus considered irreversible. Structural lesions in the thalamus and brainstem or cerebellum are usually responsible for Holmes' tremor. We present a 23-year-old woman who presented with unilateral Holmes' tremor. She also had hypersomnolence and headache in the sitting posture. Her brain imaging showed brain sagging and deep brain swelling due to spontaneous intracranial hypotension (SIH). She was managed conservatively and had a total clinical and radiological recovery. The brain sagging with the consequent distortion of the midbrain and diencephalon was responsible for this clinical presentation. SIH may be considered as one of the reversible causes of Holmes' tremor. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  1. Dipole mechanism of spontaneous breaking of N = 2 supersymmetry. II. Reformulation and generalization in harmonic superspace

    International Nuclear Information System (INIS)

    Ohta, N.

    1985-01-01

    After elucidating the component structure of N = 2 supersymmetric gauge theories in the harmonic superspace formalism with central charges, we reformulate our previous dipole mechanism of spontaneous breaking of N = 2 supersymmetry free from the Nambu-Goldstone-fermion difficulties in this formalism. This allows a generalization of our previous model of generating finiteness-preserving mass terms for scalar hypermultiplets; we can also obtain the gauge-fermion and scalar mass terms together with specific cubic interactions for scalar fields. The mechanism is equivalent to the so-called spurion method

  2. Spontaneous CP breaking in QCD and the axion potential: an effective Lagrangian approach

    Science.gov (United States)

    Di Vecchia, Paolo; Rossi, Giancarlo; Veneziano, Gabriele; Yankielowicz, Shimon

    2017-12-01

    Using the well-known low-energy effective Lagrangian of QCD — valid for small (non-vanishing) quark masses and a large number of colors — we study in detail the regions of parameter space where CP is spontaneously broken/unbroken for a vacuum angle θ = π. In the CP broken region there are first order phase transitions as one crosses θ = π, while on the (hyper)surface separating the two regions, there are second order phase transitions signalled by the vanishing of the mass of a pseudo Nambu-Goldstone boson and by a divergent QCD topological susceptibility. The second order point sits at the end of a first order line associated with the CP spontaneous breaking, in the appropriate complex parameter plane. When the effective Lagrangian is extended by the inclusion of an axion these features of QCD imply that standard calculations of the axion potential have to be revised if the QCD parameters fall in the above mentioned CP broken region, in spite of the fact that the axion solves the strong- CP problem. These last results could be of interest for axionic dark matter calculations if the topological susceptibility of pure Yang-Mills theory falls off sufficiently fast when temperature is increased towards the QCD deconfining transition.

  3. Spontaneous symmetry breaking and response functions

    International Nuclear Information System (INIS)

    Beraudo, A.; De Pace, A.; Martini, M.; Molinari, A.

    2005-01-01

    We study the quantum phase transition occurring in an infinite homogeneous system of spin 1/2 fermions in a non-relativistic context. As an example we consider neutrons interacting through a simple spin-spin Heisenberg force. The two critical values of the coupling strength-signaling the onset into the system of a finite magnetization and of the total magnetization, respectively-are found and their dependence upon the range of the interaction is explored. The spin response function of the system in the region where the spin-rotational symmetry is spontaneously broken is also studied. For a ferromagnetic interaction the spin response along the direction of the spontaneous magnetization occurs in the particle-hole continuum and displays, for not too large momentum transfers, two distinct peaks. The response along the direction orthogonal to the spontaneous magnetization displays instead, beyond a softened and depleted particle-hole continuum, a collective mode to be identified with a Goldstone boson of type II. Notably, the random phase approximation on a Hartree-Fock basis accounts for it, in particular for its quadratic-close to the origin-dispersion relation. It is shown that the Goldstone boson contributes to the saturation of the energy-weighted sum rule for ∼25% when the system becomes fully magnetized (that is in correspondence of the upper critical value of the interaction strength) and continues to grow as the interaction strength increases

  4. Interplay of Coulomb interactions and disorder in three-dimensional quadratic band crossings without time-reversal symmetry and with unequal masses for conduction and valence bands

    Science.gov (United States)

    Mandal, Ipsita; Nandkishore, Rahul M.

    2018-03-01

    Coulomb interactions famously drive three-dimensional quadratic band crossing semimetals into a non-Fermi liquid phase of matter. In a previous work [Nandkishore and Parameswaran, Phys. Rev. B 95, 205106 (2017), 10.1103/PhysRevB.95.205106], the effect of disorder on this non-Fermi liquid phase was investigated, assuming that the band structure was isotropic, assuming that the conduction and valence bands had the same band mass, and assuming that the disorder preserved exact time-reversal symmetry and statistical isotropy. It was shown that the non-Fermi liquid fixed point is unstable to disorder and that a runaway flow to strong disorder occurs. In this paper, we extend that analysis by relaxing the assumption of time-reversal symmetry and allowing the electron and hole masses to differ (but continuing to assume isotropy of the low energy band structure). We first incorporate time-reversal symmetry breaking disorder and demonstrate that there do not appear any new fixed points. Moreover, while the system continues to flow to strong disorder, time-reversal-symmetry-breaking disorder grows asymptotically more slowly than time-reversal-symmetry-preserving disorder, which we therefore expect should dominate the strong-coupling phase. We then allow for unequal electron and hole masses. We show that whereas asymmetry in the two masses is irrelevant in the clean system, it is relevant in the presence of disorder, such that the `effective masses' of the conduction and valence bands should become sharply distinct in the low-energy limit. We calculate the RG flow equations for the disordered interacting system with unequal band masses and demonstrate that the problem exhibits a runaway flow to strong disorder. Along the runaway flow, time-reversal-symmetry-preserving disorder grows asymptotically more rapidly than both time-reversal-symmetry-breaking disorder and the Coulomb interaction.

  5. Esoteric elementary particle phenomena in undergraduate physics: spontaneous symmetry breaking and scale invariance

    International Nuclear Information System (INIS)

    Greenberger, D.M.

    1978-01-01

    We take two rather abstract concepts from elementary particle physics, and show that there actually exist analogs to both of them in undergraduate physics. In the case of spontaneous symmetry breaking, we provide an example where the most symmetrical state of a simple system suddenly becomes unstable, while a less symmetrical state develops lower energy and becomes stable. In the case of scale invariance, we consider an example with no natural scale determined, and show that a straightforward dimensional analysis of the problem leads to incorrect results, because of the occurrence of infinities, even though they would appear to be irrelevant infinities that might not be expected to affect the dimensions of the answer. We then show how a simple use of the scale invariance of the problem leads to the correct answer

  6. Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials

    International Nuclear Information System (INIS)

    Adhikari, S. K.; Malomed, B. A.; Salasnich, L.; Toigo, F.

    2010-01-01

    We study the spontaneous symmetry breaking (SSB) of a superfluid Bose-Fermi (BF) mixture in a double-well potential (DWP). The mixture is described by the Gross-Pitaevskii equation (GPE) for the bosons, coupled to an equation for the order parameter of the Fermi superfluid, which is derived from the respective density functional in the unitarity limit (a similar model applies to the BCS regime, too). Straightforward SSB in the degenerate Fermi gas loaded into a DWP is impossible, as it requires an attractive self-interaction, and the intrinsic nonlinearity in the Fermi gas is repulsive. Nonetheless, we demonstrate that the symmetry breaking is possible in the mixture with attraction between fermions and bosons, like 40 K and 87 Rb. Numerical results are represented by dependencies of asymmetry parameters for both components on particle numbers of the mixture, N F and N B , and by phase diagrams in the (N F ,N B ) plane, which displays regions of symmetric and asymmetric ground states. The dynamical picture of the SSB, induced by a gradual transformation of the single-well potential into the DWP, is reported too. An analytical approximation is proposed for the case when the GPE for the boson wave function may be treated by means of the Thomas-Fermi (TF) approximation. Under a special linear relationship between N F and N B , the TF approximation allows us to reduce the model to a single equation for the fermionic function, which includes competing repulsive and attractive nonlinear terms. The latter one directly displays the mechanism of the generation of the effective attraction in the Fermi superfluid, mediated by the bosonic component of the mixture.

  7. Spontaneous breaking of chiral symmetry, and eventually of parity, in a σ-model with two Mexican hats

    International Nuclear Information System (INIS)

    Giacosa, Francesco

    2010-01-01

    A σ-model with two linked Mexican hats is discussed. This scenario could be realized in low-energy QCD when the ground state and the first excited (pseudo)scalar mesons are included, and where not only in the subspace of the ground states, but also in that of the first excited states, a Mexican hat potential is present. This possibility can change some basic features of a low-energy hadronic theory of QCD. It is also shown that spontaneous breaking of parity can occur in the vacuum for some parameter choice of the model. (orig.)

  8. Time crystals: a review

    Science.gov (United States)

    Sacha, Krzysztof; Zakrzewski, Jakub

    2018-01-01

    Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications of discrete (or Floquet) time crystals—the structures that appear in the time domain due to spontaneous breaking of discrete time translation symmetry. The struggle to observe discrete time crystals is reviewed here together with propositions that generalize this concept introducing condensed matter like physics in the time domain. We shall also revisit the original Wilczek’s idea and review strategies aimed at spontaneous breaking of continuous time translation symmetry.

  9. Spontaneously broken global symmetries and cosmology

    International Nuclear Information System (INIS)

    Shafi, Q.; Vilenkin, A.

    1984-01-01

    Phase transitions associated with spontaneously broken global symmetries, in case these occur in nature, can have important cosmological implications. This is illustrated through two examples. The first one shows how the spontaneous breaking of a global U(1) symmetry, present, for instance, in the minimal SU(5) model, can lead to an inflationary phase. The second example illustrates how topologically stable strings associated with the breaking of U(1) symmetry make an appearance at (or near) the end of the inflationary era

  10. Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales.

    Science.gov (United States)

    Curran, P J; Desoky, W M; Milosević, M V; Chaves, A; Laloë, J-B; Moodera, J S; Bending, S J

    2015-10-23

    Scanning Hall probe microscopy (SHPM) has been used to study vortex structures in thin epitaxial films of the superconductor MgB2. Unusual vortex patterns observed in MgB2 single crystals have previously been attributed to a competition between short-range repulsive and long-range attractive vortex-vortex interactions in this two band superconductor; the type 1.5 superconductivity scenario. Our films have much higher levels of disorder than bulk single crystals and therefore both superconducting condensates are expected to be pushed deep into the type 2 regime with purely repulsive vortex interactions. We observe broken symmetry vortex patterns at low fields in all samples after field-cooling from above Tc. These are consistent with those seen in systems with competing repulsions on disparate length scales, and remarkably similar structures are reproduced in dirty two band Ginzburg-Landau calculations, where the simulation parameters have been defined by experimental observations. This suggests that in our dirty MgB2 films, the symmetry of the vortex structures is broken by the presence of vortex repulsions with two different lengthscales, originating from the two distinct superconducting condensates. This represents an entirely new mechanism for spontaneous symmetry breaking in systems of superconducting vortices, with important implications for pinning phenomena and high current density applications.

  11. Spontaneous charge breaking in the NMSSM: dangerous or not?

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, Manuel E.; Opferkuch, Toby [Bethe Center for Theoretical Physics and Physikalisches Institut der Universitaet Bonn, Bonn (Germany); Staub, Florian [Karlsruhe Institute of Technology, Institute for Theoretical Physics (ITP), Karlsruhe (Germany); Karlsruhe Institute of Technology, Institute for Nuclear Physics (IKP), Eggenstein-Leopoldshafen (Germany)

    2017-05-15

    We investigate the impact of charge-breaking minima on the vacuum stability of the NMSSM. We concentrate on the case of vanishing A-terms in the sfermion sector, i.e. the only potentially dangerous sources of charge breaking are vacuum expectation values of the charged Higgs fields. We find that, in contrast to Two-Higgs-Doublet Models like the MSSM, at both tree and loop level there exist global charge-breaking minima. Consequently, many regions of parameter space are rendered metastable, which otherwise would have been considered stable if these charge-breaking minima were neglected. However, the inclusion of these new scalar field directions has little impact on otherwise metastable vacuum configurations. (orig.)

  12. Speckle-scale focusing in the diffusive regime with time reversal of variance-encoded light (TROVE)

    Science.gov (United States)

    Judkewitz, Benjamin; Wang, Ying Min; Horstmeyer, Roarke; Mathy, Alexandre; Yang, Changhuei

    2013-04-01

    Focusing of light in the diffusive regime inside scattering media has long been considered impossible. Recently, this limitation has been overcome with time reversal of ultrasound-encoded light (TRUE), but the resolution of this approach is fundamentally limited by the large number of optical modes within the ultrasound focus. Here, we introduce a new approach, time reversal of variance-encoded light (TROVE), which demixes these spatial modes by variance encoding to break the resolution barrier imposed by the ultrasound. By encoding individual spatial modes inside the scattering sample with unique variances, we effectively uncouple the system resolution from the size of the ultrasound focus. This enables us to demonstrate optical focusing and imaging with diffuse light at an unprecedented, speckle-scale lateral resolution of ~5 µm.

  13. Speckle-scale focusing in the diffusive regime with time-reversal of variance-encoded light (TROVE).

    Science.gov (United States)

    Judkewitz, Benjamin; Wang, Ying Min; Horstmeyer, Roarke; Mathy, Alexandre; Yang, Changhuei

    2013-04-01

    Focusing of light in the diffusive regime inside scattering media has long been considered impossible. Recently, this limitation has been overcome with time reversal of ultrasound-encoded light (TRUE), but the resolution of this approach is fundamentally limited by the large number of optical modes within the ultrasound focus. Here, we introduce a new approach, time reversal of variance-encoded light (TROVE), which demixes these spatial modes by variance-encoding to break the resolution barrier imposed by the ultrasound. By encoding individual spatial modes inside the scattering sample with unique variances, we effectively uncouple the system resolution from the size of the ultrasound focus. This enables us to demonstrate optical focusing and imaging with diffuse light at unprecedented, speckle-scale lateral resolution of ~ 5 μm.

  14. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  15. Physics in the intrinsic coordinate frames with the universal mean field potential: spontaneous parity breaking and exotic shapes in high-spin states

    International Nuclear Information System (INIS)

    Dudek, J.

    1989-01-01

    The concept of a ''universal'' average field as a basis of intrinsic-frame nuclear physics is stressed. The symmetries of such an average field are discussed. As an important application, an overwiew is given of the recent progress in understanding the octupole-type (intrinsic-parity breaking) degrees of freedom in nuclei. Their importance and the new consequences resulting from the related symmetries and spontaneous symmetry breaking phenomena are emphasized: the presence of static and/or dynamic isovector deformations and their implications, the possible low-energy E1 cooling in moderately hot nuclei at high spins, possible new forms of rotational dumping effects in rotating nuclei etc

  16. Introduction to time reversal theory

    International Nuclear Information System (INIS)

    Henley, E.M.

    1987-01-01

    Theory and reaction mechanisms relevant to time reversal invariance are reviewed. Consequences of time reversal invariance are presented under the headings of CP tests, electromagnetic moments, weak emissions or absorptions, and scattering reactions. 8 refs., 4 figs

  17. Introduction to symmetry-breaking phenomena in physics

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2001-01-01

    The notion of broken symmetries started slowly to emerge in the 19th century. The early studies of Pasteur on the parity asymmetry of life, the studies of Curie on piezoelectricity and on the symmetries of effects versus the symmetry of causes ( which clearly excluded spontaneous symmetry breaking), are important historical landmarks. However the possibility of spontaneous symmetry breaking within the usual principles of statistical mechanics, waited for the work of Peierls and Onsager. The whole theory of phase transitions and critical phenomena, as well as the construction of field theoretic models as long distance limit of yet unknown physics, relies nowadays on the concept of criticality associated to spontaneous symmetry breaking. The phenomena of Goldstone bosons, of Meissner-Higgs effects, are central to the theory of condensed matter as well as to particle physics. In cosmology as well, the various inflationary scenarios begin similarly with this same concept. The three lectures will provide a simple ...

  18. Status of time reversal invariance

    International Nuclear Information System (INIS)

    Henley, E.M.

    1989-01-01

    Time Reversal Invariance is introduced, and theories for its violation are reviewed. The present experimental and theoretical status of Time Reversal Invariance and tests thereof will be presented. Possible future tests will be discussed. 30 refs., 2 figs., 1 tab

  19. [Effects of reversing the feeding cycle and the light period on the spontaneous activity of the rat (author's transl)].

    Science.gov (United States)

    Ticca, M

    1976-01-01

    The amount and the circadian distribution of spontaneous activity in the rat are influenced by a number of factors, whose importance and interrelationships are still deeply discussed. In order to check the reliability of previous studies about the effects of meal-eating on the spontaneous activity (wheel running) of rats of our Sprague-Dawley strain, the adjustment to the modifications of the normal day-night cycle and of the normal nocturnal feeding rhythm have been controlled. Reversing the normal light and dark periods caused the rats, after a 24 hours period, to lower and to irregularly distribute their spontaneous activity. Rats shifted their pattern of maximal activity by 12 hours in the new period of darkness in about five days, and showed to have completely fixed the new reversed running habit. Also feeding habits changed in a similar way, but more slowly. The levels of mean daily activity did not change. In a second experiment, rats, received food during light hours, and were deprived during dark hours. Their activity increased considerably and irregularly during dark hours, while a very slight rise of wheel running was shown during light hours. Body weight gain and food consumption were similar to those of the control group. These results slightly differ from those obtained using other rat strains, and are an interesting example of reinforcement of a spontaneous behavior resulting more from the light-dark cycle than from cues provided by food deprivation.

  20. Topological Field Theory of Time-Reversal Invariant Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiao-Liang; Hughes, Taylor; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-19

    We show that the fundamental time reversal invariant (TRI) insulator exists in 4 + 1 dimensions, where the effective field theory is described by the 4 + 1 dimensional Chern-Simons theory and the topological properties of the electronic structure is classified by the second Chern number. These topological properties are the natural generalizations of the time reversal breaking (TRB) quantum Hall insulator in 2 + 1 dimensions. The TRI quantum spin Hall insulator in 2 + 1 dimensions and the topological insulator in 3 + 1 dimension can be obtained as descendants from the fundamental TRI insulator in 4 + 1 dimensions through a dimensional reduction procedure. The effective topological field theory, and the Z{sub 2} topological classification for the TRI insulators in 2+1 and 3+1 dimensions are naturally obtained from this procedure. All physically measurable topological response functions of the TRI insulators are completely described by the effective topological field theory. Our effective topological field theory predicts a number of novel and measurable phenomena, the most striking of which is the topological magneto-electric effect, where an electric field generates a magnetic field in the same direction, with an universal constant of proportionality quantized in odd multiples of the fine structure constant {alpha} = e{sup 2}/hc. Finally, we present a general classification of all topological insulators in various dimensions, and describe them in terms of a unified topological Chern-Simons field theory in phase space.

  1. Long-term hormonal contraceptive use is associated with a reversible suppression of antral follicle count and a break from hormonal contraception may improve oocyte yield.

    Science.gov (United States)

    Letourneau, Joseph M; Cakmak, Hakan; Quinn, Molly; Sinha, Nikita; I Cedars, Marcelle; Rosen, Mitchell P

    2017-09-01

    Unlike infertility, patients presenting for fertility preservation (FP) are often using combined hormonal contraceptives (CHC). We studied whether long-term (≥6 months) CHC use is associated with reversible suppression of antral follicle count (AFC). This is a longitudinal study of FP cycles from 2012 to 2016. We studied three groups: those without CHC exposure (NO CHC), those with CHC usage with a CHC break (BREAK), and without a break (NO BREAK) prior to ovarian stimulation. We assessed ovarian reserve by AFC at initial consultation and discussed the possibility of CHC suppression of AFC. Patients chose between ovarian stimulation with no CHC break versus ovarian stimulation after a CHC break. AFC was measured serially in the BREAK group. We assessed whether AFC suppression was reversed in the BREAK group. Total oocyte yield was compared among the NO CHC, BREAK, and NO BREAK groups. T tests, ANOVA, and linear/logistic regressions were used. Seven hundred forty-three women underwent FP. Twenty-one percent (n = 154) were taking long-term CHC (≥6 months). AFC suppression was more likely with CHC use (OR 1.6, 95% CI 1.1-2.4, P = 0.011). The BREAK group (n = 79) stopped CHC for an average of 4 months. AFC improvement started at 1 month and plateaued at approximately 6- to 7-month break. The BREAK group had approximately twice as many oocytes per initial AFC as NO BREAK (2.8 ± 3.8 vs. 1.4 ± 0.9, P women present for FP on CHC, AFC may be suppressed. A CHC break of several months is associated with an increase in AFC and a potential improvement in overall egg yield.

  2. Dynamical symmetry breaking with hypercolour and high colour representations

    International Nuclear Information System (INIS)

    Zoupanos, G.

    1985-01-01

    A model is presented in which the electroweak gauge group is spontaneously broken according to a dynamical scenario based on the existence of high colour representations. An unattractive feature of this scenario was the necessity to introduce elementary Higgs fields in order to obtain the spontaneous symmetry breaking of part of the theory. In the present model, this breaking can also be understood dynamically with the introduction of hypercolour interactions. (author)

  3. Spontaneous direct and reverse osmosis

    International Nuclear Information System (INIS)

    Valitov, N.Kh.

    1996-01-01

    It has been ascertained experimentally that in the course of separation of CsCl, KCl, NaCl aqueous solutions by semi-permeable membrane from distilled water the direct and then reverse osmosis are observed. The same sequence is observed in case of separation of CsCl aqueous solutions from NaCl of different concentrations. The reason for the direct and reverse osmosis has been explained. 5 refs.; 3 figs. 1 tab

  4. Defining time crystals via representation theory

    Science.gov (United States)

    Khemani, Vedika; von Keyserlingk, C. W.; Sondhi, S. L.

    2017-09-01

    Time crystals are proposed states of matter which spontaneously break time translation symmetry. There is no settled definition of such states. We offer a new definition which follows the traditional recipe for Wigner symmetries and order parameters. Supplementing our definition with a few plausible assumptions we find that a) systems with time-independent Hamiltonians should not exhibit time translation symmetry breaking while b) the recently studied π spin glass/Floquet time crystal can be viewed as breaking a global internal symmetry and as breaking time translation symmetry, as befits its two names.

  5. Gauge principle, vector-meson dominance, and spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Nambu, Yoichiro

    1989-01-01

    The author concentrates on certain theoretical developments of the late 1950s which are concerned with the meaning and role of symmetries and symmetry breaking, and especially work done in Chicago, and notes his own involvement in this debate. He worked on symmetry-breaking in superconductivity, using a four-fermion interaction model. (UK)

  6. Dynamic spontaneous breaking of gauge invariance in asymptotically free theories. [Mechanism mass, group renormalization

    Energy Technology Data Exchange (ETDEWEB)

    Ansel' m, A A; D' yakonov, D I [AN SSSR, Leningrad. Inst. Yadernoj Fiziki

    1975-01-01

    The mechanism of dynamic spontaneous breaking of the Coleman-Weinberg gauge invariance is discussed in which scalar fields assume nonzero mean values owing to quantum effects in higher orders of the perturbation theory. Group renormalization methods are used to study scalar electrodynamics and gauge theories similar to that of Yang and Mills; for these gauge theories it is established that by choosing proper constants it is possible to combine the acquisition of a mass by particles, owing to a dynamic violation of symmetry, with the asymptotic freedom of the theory. The symmetry violation is found to be closely related to infrared poles observed in effective charge for asymptotically free theories. The emerging masses of particles automatically cover these poles. It is proved that physical results due to symmetry violation do not depend, at least in the first non-trivial order of the perturbation theory, on the initial gauging of vector fields.

  7. Secondary School Students with Disabilities at Break Time

    Directory of Open Access Journals (Sweden)

    Josué ARTILES RODRÍGUEZ

    2017-01-01

    Full Text Available Break time fulfills an important role in the social development of students, providing free time for interaction where they are able to practice their abilities of making contact with others. Students with disabilities do not see themselves in the same light because they consider this activity an unstructured one to get on with. Break planning and mediation carried out by other pupils eases relationships between both groups and offers a natural learning environment among students, according to inclusive education principles. This research has been carried out by investigating multiple cases in three special education classrooms which belong to secondary schools, with a total of 19 students with disabilities. Over the course of three months of observation, 3,420 interaction instances were obtained which were linked with the students’ interviews. The results show a lower number of relationships between students belonging to classrooms with no planned breaks in their schedule and those classrooms which did plan their breaks and peer mediation. The practical implications are discussed.

  8. The scale of supersymmetry breaking as a free parameter

    International Nuclear Information System (INIS)

    Polonsky, N.

    2001-01-01

    While supersymmetric extensions of the Standard Model can be fully described in terms of explicitly broken global supersymmetry, this description is only effective. Once related to spontaneous breaking in a more fundamental theory, the effective parameters translate to functions of two distinct scales, the scale of spontaneous supersymmetry breaking and the scale of its mediation to the standard-model fields. The scale dependence will be written explicitly and the full spectrum of supersymmetry breaking operators which emerges will be explored. It will be shown that, contrary to common lore, scale-dependent operators can play an important role in determining the phenomenology. For example, theories with low-energy supersymmetry breaking, such as gauge mediation, may correspond to a scalar potential which is quite different than in theories with high-energy supersymmetry breaking, such as gravity mediation. As a concrete example, the Higgs mass prediction will be discussed in some detail and its upper bound will be shown to be sensitive to the supersymmetry breaking scale

  9. Spontaneous and stimulated emission induced by an electron, electron bunch, and electron beam in a plasma

    International Nuclear Information System (INIS)

    Kuzelev, M V; Rukhadze, A A

    2008-01-01

    Two fundamental mechanisms - the Cherenkov effect and anomalous Doppler effect - underlying the emission by an electron during its superluminal motion in medium are considered. Cherenkov emission induced by a single electron and a small electron bunch is spontaneous. In the course of spontaneous Cherenkov emission, the translational motion of an electron is slowed down and the radiation energy grows linearly with time. As the number of radiating electrons increases, Cherenkov emission becomes stimulated. Stimulated Cherenkov emission represents a resonance beam instability. This emission process is accompanied by longitudinal electron bunching in the beam or by the breaking of an electron bunch into smaller bunches, in which case the radiation energy grows exponentially with time. In terms of the longitudinal size L e of the electron bunch there is a transition region λ e 0 -1 between the spontaneous and stimulated Cherenkov effects, where λ is the average radiation wavelength, and δ 0 is the dimensionless (in units of the radiation frequency) growth rate of the Cherenkov beam instability. The range to the left of this region is dominated by spontaneous emission, whereas the range to the right of this region is dominated by stimulated emission. In contrast to the Vavilov-Cherenkov effect, the anomalous Doppler effect should always (even for a single electron) be considered as stimulated, because it can only be explained by accounting for the reverse action of the radiation field on the moving electron. During stimulated emission in conditions where anomalous Doppler effect shows itself, an electron is slowed down and spins up; in this case, the radiation energy grows exponentially with time. (reviews of topical problems)

  10. Evolutionary Algorithms for the Detection of Structural Breaks in Time Series

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Fischer, Paul; Hilbert, Astrid

    2013-01-01

    Detecting structural breaks is an essential task for the statistical analysis of time series, for example, for fitting parametric models to it. In short, structural breaks are points in time at which the behavior of the time series changes. Typically, no solid background knowledge of the time...

  11. Rotational Symmetry Breaking in Baby Skyrme Models

    Science.gov (United States)

    Karliner, Marek; Hen, Itay

    We discuss one of the most interesting phenomena exhibited by baby skyrmions - breaking of rotational symmetry. The topics we will deal with here include the appearance of rotational symmetry breaking in the static solutions of baby Skyrme models, both in flat as well as in curved spaces, the zero-temperature crystalline structure of baby skyrmions, and finally, the appearance of spontaneous breaking of rotational symmetry in rotating baby skyrmions.

  12. Reversible perspective and splitting in time.

    Science.gov (United States)

    Hart, Helen Schoenhals

    2012-01-01

    The element of time--the experience of it and the defensive use of it--is explored in conjunction with the use of reversible perspective as a psychotic defense. Clinical material from a long analysis illustrates how a psychotic patient used the reversible perspective, with its static splitting, to abolish the experience of time. When he improved and the reversible perspective became less effective for him, he replaced it with a more dynamic splitting mechanism using time gaps. With further improvement, the patient began to experience the passage of time, and along with it the excruciating pain of separation, envy, and loss.

  13. N=1 superstrings with spontaneously broken symmetries

    International Nuclear Information System (INIS)

    Ferrara, S.

    1988-01-01

    We construct N=1 chiral superstrings with spontaneously broken gauge symmetry in four space-time dimensions. These new string solutions are obtained by a generalized coordinate-dependent Z 2 orbifold compactification of some non-chiral five-dimensional N=1 and N=2 superstrings. The scale of symmetry breaking is arbitrary (at least classically) and it can be chosen hierarchically smaller than the string scale (α') -1/2 . (orig.)

  14. Time reversibility in the quantum frame

    Energy Technology Data Exchange (ETDEWEB)

    Masot-Conde, Fátima [Escuela Superior Ingenieros, Dpt. Física Aplicada III, Universidad de Sevilla Isla Mágica, 41092- Sevilla (Spain)

    2014-12-04

    Classic Mechanics and Electromagnetism, conventionally taken as time-reversible, share the same concept of motion (either of mass or charge) as the basis of the time reversibility in their own fields. This paper focuses on the relationship between mobile geometry and motion reversibility. The goal is to extrapolate the conclusions to the quantum frame, where matter and radiation behave just as elementary mobiles. The possibility that the asymmetry of Time (Time’s arrow) is an effect of a fundamental quantum asymmetry of elementary particles, turns out to be a consequence of the discussion.

  15. Boost breaking in the EFT of inflation

    Energy Technology Data Exchange (ETDEWEB)

    Delacrétaz, Luca V.; Senatore, Leonardo [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States); Noumi, Toshifumi, E-mail: lvd@stanford.edu, E-mail: tnoumi@phys.sci.kobe-u.ac.jp, E-mail: senatore@stanford.edu [Jockey Club Institute for Advanced Study, Hong Kong University of Science and Technology (Hong Kong)

    2017-02-01

    If time-translations are spontaneously broken, so are boosts. This symmetry breaking pattern can be non-linearly realized by either just the Goldstone boson of time translations, or by four Goldstone bosons associated with time translations and boosts. In this paper we extend the Effective Field Theory of Multifield Inflation to consider the case in which the additional Goldstone bosons associated with boosts are light and coupled to the Goldstone boson of time translations. The symmetry breaking pattern forces a coupling to curvature so that the mass of the additional Goldstone bosons is predicted to be equal to √2 H in the vast majority of the parameter space where they are light. This pattern therefore offers a natural way of generating self-interacting particles with Hubble mass during inflation. After constructing the general effective Lagrangian, we study how these particles mix and interact with the curvature fluctuations, generating potentially detectable non-Gaussian signals.

  16. Fuel bundle movement due to reverse flow

    Energy Technology Data Exchange (ETDEWEB)

    Wahba, N N; Akalin, O [Ontario Hydro, Toronto, ON (Canada)

    1996-12-31

    When a break occurs in the inlet feeder or inlet header, the rapid depressurization will cause the channel flow to reverse forcing the string of bundles to accelerate and impact with upstream shield plug. A model has been developed to predict the bundle motion due to the channel flow reversal. The model accounts for various forces acting on the bundle. A series of five reverse flow, bundle acceleration experiments have been conducted simulating a break in the inlet feeder of a CANDU fuel channel. The model has been validated against the experiments. The predicted impact velocities are in good agreement with the measured values. It is demonstrated that the model may be successfully used in predicting bundle relocation timing following a large LOCA (loss of coolant). (author). 7 refs., 3 tabs., 11 figs.

  17. Neural network classifications and correlation analysis of EEG and MEG activity accompanying spontaneous reversals of the Necker cube.

    Science.gov (United States)

    Gaetz, M; Weinberg, H; Rzempoluck, E; Jantzen, K J

    1998-04-01

    It has recently been suggested that reentrant connections are essential in systems that process complex information [A. Damasio, H. Damasio, Cortical systems for the retrieval of concrete knowledge: the convergence zone framework, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 61-74; G. Edelman, The Remembered Present, Basic Books, New York, 1989; M.I. Posner, M. Rothbart, Constructing neuronal theories of mind, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 183-199; C. von der Malsburg, W. Schneider, A neuronal cocktail party processor, Biol. Cybem., 54 (1986) 29-40]. Reentry is not feedback, but parallel signalling in the time domain between spatially distributed maps, similar to a process of correlation between distributed systems. Accordingly, it was expected that during spontaneous reversals of the Necker cube, complex patterns of correlations between distributed systems would be present in the cortex. The present study included EEG (n=4) and MEG recordings (n=5). Two experimental questions were posed: (1) Can distributed cortical patterns present during perceptual reversals be classified differently using a generalised regression neural network (GRNN) compared to processing of a two-dimensional figure? (2) Does correlated cortical activity increase significantly during perception of a Necker cube reversal? One-second duration single trials of EEG and MEG data were analysed using the GRNN. Electrode/sensor pairings based on cortico-cortical connections were selected to assess correlated activity in each condition. The GRNN significantly classified single trials recorded during Necker cube reversals as different from single trials recorded during perception of a two-dimensional figure for both EEG and MEG. In addition, correlated cortical activity increased significantly in the Necker cube reversal condition for EEG and MEG compared

  18. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of a health claim related to coffee C21 and reduction of spontaneous DNA strand breaks pursuant to Article 13(5) of Regulation (EC) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    of coffee compared to water on spontaneous DNA strand breaks. The evidence provided in animal and in vitro studies is not sufficient to predict the occurrence of an effect of coffee C21 consumption on the reduction of spontaneous DNA strand breaks in humans. The Panel concludes that a cause and effect......Following an application from Tchibo GmbH, submitted pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of Germany, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver an opinion on the scientific substantiation of a health claim related...... to coffee C21 and reduction of spontaneous DNA strand breaks. The scope of the application was proposed to fall under a health claim based on newly developed scientific evidence. The food constituent that is the subject of the health claim is coffee C21, which is sufficiently characterised. The claimed...

  19. Simultaneous and spontaneous reversal of positional nystagmus; an unusual peripheral sign of benign paroxysmal positional vertigo

    Directory of Open Access Journals (Sweden)

    Sertac Yetiser, MD

    2017-06-01

    Full Text Available Direction-changing positional nystagmus is generally thought to be of central origin. Reversal of initial positional nystagmus during maintaining the head position in patients with benign paroxysmal positional vertigo (BPPV is quite unusual and could be a sign of peripheral pathology. Vestibular reflex adaptation, simultaneous co-existence of canalolithiasis and cupulolithiasis in the same or both ears and changing in direction of debris movement have been proposed for the mechanism of this phenomenon. This can be a sign of simultaneous ampullopedal and ampulofugal flows during single head movement. This double-phase pattern of flow causing reversal of positional nystagmus could be related with the amount, location and dispersal of otolithic debris inside the membranous labyrinth. Four patients (3 lateral canal canalolithiasis and 1 posterior canal with reversing spontaneous nystagmus among 530 patients with BPPV have been identified in our clinic. They have been cured with standard re-positioning maneuvers. Endolymphatic reflux theory has been proposed as the underlying mechanism for unusual behavior of otolithic debris.

  20. On the character of scale symmetry breaking in gauge theories

    International Nuclear Information System (INIS)

    Gusijnin, V.P.; Kushnir, V.A.; Miransky, V.A.

    1988-01-01

    The problem of scale symmetry breaking in gauge theories is discussed. It is shown that the phenomenon of spontaneous breaking of scale symmetry in gauge theories is incompatible with the PCAAC dynamics. 12 refs

  1. Detecting structural breaks in time series via genetic algorithms

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Fischer, Paul; Hilbert, Astrid

    2016-01-01

    of the time series under consideration is available. Therefore, a black-box optimization approach is our method of choice for detecting structural breaks. We describe a genetic algorithm framework which easily adapts to a large number of statistical settings. To evaluate the usefulness of different crossover...... and mutation operations for this problem, we conduct extensive experiments to determine good choices for the parameters and operators of the genetic algorithm. One surprising observation is that use of uniform and one-point crossover together gave significantly better results than using either crossover...... operator alone. Moreover, we present a specific fitness function which exploits the sparse structure of the break points and which can be evaluated particularly efficiently. The experiments on artificial and real-world time series show that the resulting algorithm detects break points with high precision...

  2. Spectroscopic Visualization of Inversion and Time-Reversal Symmetry Breaking Weyl Semi-metals

    Science.gov (United States)

    Beidenkopf, Haim

    A defining property of a topological material is the existence of surface bands that cannot be realized but as the termination of a topological bulk. In a Weyl semi-metal these surface states are in the form of Fermi-arcs. Their open-contour Fermi-surface curves between pairs of surface projections of bulk Weyl cones. Such Dirac-like bulk bands, as opposed to the gapped bulk of topological insulators, land a unique opportunity to examine the deep notion of bulk to surface correspondence. We study the intricate properties both of inversion symmetry broken and of time-reversal symmetry broken Weyl semimetals using scanning tunneling spectroscopy. We visualize the Fermi arc states on the surface of the non-centrosymmetric Weyl semi-metal TaAs. Using the distinct structure and spatial distribution of the wavefunctions associated with the different topological and trivial bands we detect the scattering processes that involve Fermi arcs. Each of these imaged scattering processes entails information on the unique nature of Fermi arcs and their correspondence to the topological bulk. We further visualize the magnetic response of the candidate magnetic Weyl semimetal GdPtBi in which the magnetic order parameter is coupled to the topological classification. European Research Council (ERC-StG no. 678702, TOPO-NW\\x9D), the Israel Science Foundation (ISF), and the United States-Israel Binational Science Foundation (BSF).

  3. Engineering and Scaling the Spontaneous Magnetization Reversal of Faraday Induced Magnetic Relaxation in Nano-Sized Amorphous Ni Coated on Crystalline Au.

    Science.gov (United States)

    Li, Wen-Hsien; Lee, Chi-Hung; Kuo, Chen-Chen

    2016-05-28

    We report on the generation of large inverse remanent magnetizations in nano-sized core/shell structure of Au/Ni by turning off the applied magnetic field. The remanent magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before the switching off of the magnetic field. Spontaneous reversal in direction and increase in magnitude of the remanent magnetization in subsequent relaxations over time were found. All of the various types of temporal relaxation curves of the remanent magnetizations are successfully scaled by a stretched exponential decay profile, characterized by two pairs of relaxation times and dynamic exponents. The relaxation time is used to describe the reduction rate, while the dynamic exponent describes the dynamical slowing down of the relaxation through time evolution. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction.

  4. Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems.

    Science.gov (United States)

    Sharif-Kashani, Pooria; Fanney, Douglas; Injev, Val

    2014-07-30

    Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery.

  5. The pseudo-conformal universe: scale invariance from spontaneous breaking of conformal symmetry

    International Nuclear Information System (INIS)

    Hinterbichler, Kurt; Khoury, Justin

    2012-01-01

    We present a novel theory of the very early universe which addresses the traditional horizon and flatness problems of big bang cosmology and predicts a scale invariant spectrum of perturbations. Unlike inflation, this scenario requires no exponential accelerated expansion of space-time. Instead, the early universe is described by a conformal field theory minimally coupled to gravity. The conformal fields develop a time-dependent expectation value which breaks the flat space so(4,2) conformal symmetry down to so(4,1), the symmetries of de Sitter, giving perturbations a scale invariant spectrum. The solution is an attractor, at least in the case of a single time-dependent field. Meanwhile, the metric background remains approximately flat but slowly contracts, which makes the universe increasingly flat, homogeneous and isotropic, akin to the smoothing mechanism of ekpyrotic cosmology. Our scenario is very general, requiring only a conformal field theory capable of developing the appropriate time-dependent expectation values, and encompasses existing incarnations of this idea, specifically the U(1) model of Rubakov and the Galileon Genesis scenario. Its essential features depend only on the symmetry breaking pattern and not on the details of the underlying lagrangian. It makes generic observational predictions that make it potentially distinguishable from standard inflation, in particular significant non-gaussianities and the absence of primordial gravitational waves

  6. Spontaneous Rotational Inversion in Phycomyces

    KAUST Repository

    Goriely, Alain

    2011-03-01

    The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stagea IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stagea IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stagea IVb). This phase lasts for 24-48Ah and is sometimes followed by yet another reversal (stageAIVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness. © 2011 American Physical Society.

  7. dRGT theory of massive gravity from spontaneous symmetry breaking

    Science.gov (United States)

    Torabian, Mahdi

    2018-05-01

    In this note we propose a topological action for a Poincare times diffeomorphism invariant gauge theory. We show that there is Higgs phase where the gauge symmetry is spontaneous broken to a diagonal Lorentz subgroup and gives the Einstein-Hilbert action plus the dRGT potential terms. In this vacuum, there are five (three from Goldstone modes) propagating degrees of freedom which form polarizations of a massive spin 2 particle, an extra healthy heavy scalar (Higgs) mode and no Boulware-Deser ghost mode. We further show that the action can be derived in a limit from a topological de Sitter invariant gauge theory in 4 dimensions.

  8. Engineering and Scaling the Spontaneous Magnetization Reversal of Faraday Induced Magnetic Relaxation in Nano-Sized Amorphous Ni Coated on Crystalline Au

    Science.gov (United States)

    Li, Wen-Hsien; Lee, Chi-Hung; Kuo, Chen-Chen

    2016-01-01

    We report on the generation of large inverse remanent magnetizations in nano-sized core/shell structure of Au/Ni by turning off the applied magnetic field. The remanent magnetization is very sensitive to the field reduction rate as well as to the thermal and field processes before the switching off of the magnetic field. Spontaneous reversal in direction and increase in magnitude of the remanent magnetization in subsequent relaxations over time were found. All of the various types of temporal relaxation curves of the remanent magnetizations are successfully scaled by a stretched exponential decay profile, characterized by two pairs of relaxation times and dynamic exponents. The relaxation time is used to describe the reduction rate, while the dynamic exponent describes the dynamical slowing down of the relaxation through time evolution. The key to these effects is to have the induced eddy current running beneath the amorphous Ni shells through Faraday induction. PMID:28773549

  9. Inflationary implications of supersymmetry breaking

    NARCIS (Netherlands)

    Borghese, Andrea; Roest, Diederik; Zavala, Ivonne

    2013-01-01

    We discuss a general bound on the possibility to realise inflation in any minimal supergravity with F-terms. The derivation crucially depends on the sGoldstini, the scalar field directions that are singled out by spontaneous supersymmetry breaking. The resulting bound involves both slow-roll

  10. Gauge symmetry breaking in gauge theories -- in search of clarification

    NARCIS (Netherlands)

    Friederich, Simon

    2013-01-01

    The paper investigates the spontaneous breaking of gauge symmetries in gauge theories from a philosophical angle, taking into account the fact that the notion of a spontaneously broken local gauge symmetry, though widely employed in textbook expositions of the Higgs mechanism, is not supported by

  11. Phase transition of the first kind with respect to the density in a model of spontaneous breaking of chiral symmetry

    International Nuclear Information System (INIS)

    Bogolyubov, N.P.

    1988-01-01

    A model of the spontaneous breaking of chiral symmetry motivated by quantum chromodynamics is considered at a finite density of the quarks and zero temperature. For zero chemical potential the dynamical quark mass, the bag constant, and the vacuum expectation value are estimated. The dependence of the grand thermodynamic potential on the chemical potential of the quarks and of the energy on the particle number density are calculated. It is found that there is a phase transition of the first kind with respect to the density of the quarks accompanied by restoration of the chiral symmetry. The critical values of the fermion density are found

  12. Discrete symmetries, strong CP problem and gravity

    International Nuclear Information System (INIS)

    Senjanovic, G.

    1993-05-01

    Spontaneous breaking of parity or time reversal invariance offers a solution to the strong CP problem, the stability of which under quantum gravitational effects provides an upper limit on the scale of symmetry breaking. Even more important, these Planck scale effects may provide a simple and natural way out of the resulting domain wall problem. (author). 22 refs

  13. Optical Time Reversal from Time-Dependent Epsilon-Near-Zero Media

    Science.gov (United States)

    Vezzoli, Stefano; Bruno, Vincenzo; DeVault, Clayton; Roger, Thomas; Shalaev, Vladimir M.; Boltasseva, Alexandra; Ferrera, Marcello; Clerici, Matteo; Dubietis, Audrius; Faccio, Daniele

    2018-01-01

    Materials with a spatially uniform but temporally varying optical response have applications ranging from magnetic field-free optical isolators to fundamental studies of quantum field theories. However, these effects typically become relevant only for time variations oscillating at optical frequencies, thus presenting a significant hurdle that severely limits the realization of such conditions. Here we present a thin-film material with a permittivity that pulsates (uniformly in space) at optical frequencies and realizes a time-reversing medium of the form originally proposed by Pendry [Science 322, 71 (2008), 10.1126/science.1162087]. We use an optically pumped, 500 nm thick film of epsilon-near-zero (ENZ) material based on Al-doped zinc oxide. An incident probe beam is both negatively refracted and time reversed through a reflected phase-conjugated beam. As a result of the high nonlinearity and the refractive index that is close to zero, the ENZ film leads to time reversed beams (simultaneous negative refraction and phase conjugation) with near-unit efficiency and greater-than-unit internal conversion efficiency. The ENZ platform therefore presents the time-reversal features required, e.g., for efficient subwavelength imaging, all-optical isolators and fundamental quantum field theory studies.

  14. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai; Schuster, Gerard T.

    2016-01-01

    Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

  15. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2016-09-06

    Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

  16. Defining Time Crystals via Representation Theory

    OpenAIRE

    Khemani, Vedika; von Keyserlingk, C. W.; Sondhi, S. L.

    2016-01-01

    Time crystals are proposed states of matter which spontaneously break time translation symmetry. There is no settled definition of such states. We offer a new definition which follows the traditional recipe for Wigner symmetries and order parameters. Supplementing our definition with a few plausible assumptions we find that a) systems with time independent Hamiltonians should not exhibit TTSB while b) the recently studied $\\pi$ spin glass/Floquet time crystal can be viewed as breaking a globa...

  17. Dynamics of symmetry breaking in strongly coupled QED

    International Nuclear Information System (INIS)

    Bardeen, W.A.

    1988-10-01

    I review the dynamical structure of strong coupled QED in the quenched planar limit. The symmetry structure of this theory is examined with reference to the nature of both chiral and scale symmetry breaking. The renormalization structure of the strong coupled phase is analysed. The compatibility of spontaneous scale and chiral symmetry breaking is studied using effective lagrangian methods. 14 refs., 3 figs

  18. II. The Standard Model in the Isotopic Foldy-Wouthuysen Representation without Higgs Bosons in the Fermion Sector. Spontaneous Breaking of Parity and "Dark Matter" Problems

    OpenAIRE

    Neznamov, V. P.

    2011-01-01

    The Standard Model with massive fermions is formulated in the isotopic Foldy-Wouthuysen representation. SU(2)xU(1) - invariance of the theory in this representation is independent of whether fermions possess mass or not, and, consequently, it is not necessary to introduce interactions between Higgs bosons and fermions. The study discusses a possible relation between spontaneous breaking of parity in the isotopic Foldy-Wouthuysen representation and the composition of elementary particles of "d...

  19. Supersymmetry breaking at finite temperature

    International Nuclear Information System (INIS)

    Kratzert, K.

    2002-11-01

    The mechanism of supersymmetry breaking at finite temperature is still only partly understood. Though it has been proven that temperature always breaks supersymmetry, the spontaneous nature of this breaking remains unclear, in particular the role of the Goldstone fermion. The aim of this work is to unify two existing approaches to the subject. From a hydrodynamic point of view, it has been argued under very general assumptions that in any supersymmetric quantum field theory at finite temperature there should exist a massless fermionic collective excitation, named phonino because of the analogy to the phonon. In the framework of a self-consistent resummed perturbation theory, it is shown for the example of the Wess-Zumino model that this mode fits very well into the quantum field theoretical framework pursued by earlier works. Interpreted as a bound state of boson and fermion, it contributes to the supersymmetric Ward-Takahashi identities in a way showing that supersymmetry is indeed broken spontaneously with the phonino playing the role of the Goldstone fermion. The second part of the work addresses the case of supersymmetric quantum electrodynamics. It is shown that also here the phonino exists and must be interpreted as the Goldstone mode. This knowledge allows a generalization to a wider class of models. (orig.)

  20. Time reversal communication system

    Science.gov (United States)

    Candy, James V.; Meyer, Alan W.

    2008-12-02

    A system of transmitting a signal through a channel medium comprises digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. The channel medium may be air, earth, water, tissue, metal, and/or non-metal.

  1. Evidence for Time-Reversal Symmetry Breaking of the Superconducting State near Twin-Boundary Interfaces in FeSe Revealed by Scanning Tunneling Spectroscopy

    Directory of Open Access Journals (Sweden)

    T. Watashige

    2015-08-01

    Full Text Available Junctions and interfaces consisting of unconventional superconductors provide an excellent experimental playground to study exotic phenomena related to the phase of the order parameter. Not only does the complex structure of unconventional order parameters have an impact on the Josephson effects, but it also may profoundly alter the quasiparticle excitation spectrum near a junction. Here, by using spectroscopic-imaging scanning tunneling microscopy, we visualize the spatial evolution of the LDOS near twin boundaries (TBs of the nodal superconductor FeSe. The π/2 rotation of the crystallographic orientation across the TB twists the structure of the unconventional order parameter, which may, in principle, bring about a zero-energy LDOS peak at the TB. The LDOS at the TB observed in our study, in contrast, does not exhibit any signature of a zero-energy peak, and an apparent gap amplitude remains finite all the way across the TB. The low-energy quasiparticle excitations associated with the gap nodes are affected by the TB over a distance more than an order of magnitude larger than the coherence length ξ_{ab}. The modification of the low-energy states is even more prominent in the region between two neighboring TBs separated by a distance ≈7ξ_{ab}. In this region, the spectral weight near the Fermi level (≈±0.2  meV due to the nodal quasiparticle spectrum is almost completely removed. These behaviors suggest that the TB induces a fully gapped state, invoking a possible twist of the order parameter structure, which breaks time-reversal symmetry.

  2. Chiral symmetry breaking and the pion quark structure

    International Nuclear Information System (INIS)

    Bernard, V.

    1986-01-01

    The mechanism of dynamical breaking of chiral symmetry in hadronic matter is first studied in the framework of the Nambu and Jona-Lasinio model on one hand and its generalisation to finite hadron size on the other hand. The analysis uses a variational procedure modelled after the BCS superconductor. Our study indicates for example, a great sensitivity of various quantities characterizing the breaking of symmetry to the shape of the interaction. Also the mechanism of breaking of chiral symmetry is essentially related to the mechanism of confinement. When a symmetry is spontaneously broken, there exists a Goldstone particle of zero mass. This is true in our model. This particle, the pion, is obtained as solution of a Bethe Salpeter equation for a qantiq bound state. This enables us to establish a connection between the pion as a Goldstone boson related to spontaneous symmetry breaking and the quark-antiquark structure of the pion. The finite mass of the physical pion is obtained with non zero current quark mass. Various properties of this particle are then studied in the RPA formalism. One important point of our model is the highly collective character of the pion. 85 refs [fr

  3. Time reversibility of quantum diffusion in small-world networks

    Science.gov (United States)

    Han, Sung-Guk; Kim, Beom Jun

    2012-02-01

    We study the time-reversal dynamics of a tight-binding electron in the Watts-Strogatz (WS) small-world networks. The localized initial wave packet at time t = 0 diffuses as time proceeds until the time-reversal operation, together with the momentum perturbation of the strength η, is made at the reversal time T. The time irreversibility is measured by I = |Π( t = 2 T) - Π( t = 0)|, where Π is the participation ratio gauging the extendedness of the wavefunction and for convenience, t is measured forward even after the time reversal. When η = 0, the time evolution after T makes the wavefunction at t = 2 T identical to the one at t = 0, and we find I = 0, implying a null irreversibility or a complete reversibility. On the other hand, as η is increased from zero, the reversibility becomes weaker, and we observe enhancement of the irreversibility. We find that I linearly increases with increasing η in the weakly-perturbed region, and that the irreversibility is much stronger in the WS network than in the local regular network.

  4. Spontaneous decoherence of coupled harmonic oscillators confined in a ring

    Science.gov (United States)

    Gong, ZhiRui; Zhang, ZhenWei; Xu, DaZhi; Zhao, Nan; Sun, ChangPu

    2018-04-01

    We study the spontaneous decoherence of coupled harmonic oscillators confined in a ring container, where the nearest-neighbor harmonic potentials are taken into consideration. Without any external symmetry-breaking field or surrounding environment, the quantum superposition state prepared in the relative degrees of freedom gradually loses its quantum coherence spontaneously. This spontaneous decoherence is interpreted by the gauge couplings between the center-of-mass and the relative degrees of freedoms, which actually originate from the symmetries of the ring geometry and the corresponding nontrivial boundary conditions. In particular, such spontaneous decoherence does not occur at all at the thermodynamic limit because the nontrivial boundary conditions become the trivial Born-von Karman boundary conditions when the perimeter of the ring container tends to infinity. Our investigation shows that a thermal macroscopic object with certain symmetries has a chance for its quantum properties to degrade even without applying an external symmetry-breaking field or surrounding environment.

  5. Supersymmetry breaking and Nambu-Goldstone fermions with cubic dispersion

    Science.gov (United States)

    Sannomiya, Noriaki; Katsura, Hosho; Nakayama, Yu

    2017-03-01

    We introduce a lattice fermion model in one spatial dimension with supersymmetry (SUSY) but without particle number conservation. The Hamiltonian is defined as the anticommutator of two nilpotent supercharges Q and Q†. Each supercharge is built solely from spinless fermion operators and depends on a parameter g . The system is strongly interacting for small g , and in the extreme limit g =0 , the number of zero-energy ground states grows exponentially with the system size. By contrast, in the large-g limit, the system is noninteracting and SUSY is broken spontaneously. We study the model for modest values of g and show that under certain conditions spontaneous SUSY breaking occurs in both finite and infinite chains. We analyze the low-energy excitations both analytically and numerically. Our analysis suggests that the Nambu-Goldstone fermions accompanying the spontaneous SUSY breaking have cubic dispersion at low energies.

  6. Reverse time migration by Krylov subspace reduced order modeling

    Science.gov (United States)

    Basir, Hadi Mahdavi; Javaherian, Abdolrahim; Shomali, Zaher Hossein; Firouz-Abadi, Roohollah Dehghani; Gholamy, Shaban Ali

    2018-04-01

    Imaging is a key step in seismic data processing. To date, a myriad of advanced pre-stack depth migration approaches have been developed; however, reverse time migration (RTM) is still considered as the high-end imaging algorithm. The main limitations associated with the performance cost of reverse time migration are the intensive computation of the forward and backward simulations, time consumption, and memory allocation related to imaging condition. Based on the reduced order modeling, we proposed an algorithm, which can be adapted to all the aforementioned factors. Our proposed method benefit from Krylov subspaces method to compute certain mode shapes of the velocity model computed by as an orthogonal base of reduced order modeling. Reverse time migration by reduced order modeling is helpful concerning the highly parallel computation and strongly reduces the memory requirement of reverse time migration. The synthetic model results showed that suggested method can decrease the computational costs of reverse time migration by several orders of magnitudes, compared with reverse time migration by finite element method.

  7. Toughening elastomers with sacrificial bonds and watching them break.

    Science.gov (United States)

    Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

    2014-04-11

    Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials.

  8. Spontaneous CP violation from a quaternionic Kaluza-Klein theory

    International Nuclear Information System (INIS)

    Hanlon, B.E.; Joshi, G.C.

    1991-01-01

    Motivated by the isomorphism between the universal covering group of the six dimensional Lorentz group and the special linear group over the quaternions, a locally quaternionic covariant quantum mechanics is postulated to exist in six space-time dimensions. Compactifying onto the space-time M 4 x S 2 complex theory is retrieved on the four dimensional Minkowski space with the essential quaternionic nature confined to S 2 . Quaternionic spinors are introduced and a dimensionally reduced theory recovered which exhibits a CP violating effect via spontaneous symmetry breaking. 20 refs

  9. The experimental investigation of supersymmetry breaking

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1996-04-01

    If Nature is supersymmetric at the weak interaction scale, what can we hope to learn from experiments on supersymmetric particles? The most mysterious aspect of phenomenological supersymmetry is the mechanism of spontaneous supersymmetry breaking. This mechanism ties the observable pattern of supersymmetric particle masses to aspects of the underlying unified theory at very small distance scales. In this article, I will discuss a systematic experimental program to determine the mechanism of supersymmetry breaking. Both pp and e + e - colliders of the next generation play an essential role

  10. Spontaneous symmetry breaking in ΡΤ symmetric systems with nonlinear damping

    International Nuclear Information System (INIS)

    Karthiga, S.; Chandrasekar, V.K.; Senthilvelan, M.; Lakshmanan, M.

    2016-01-01

    In this talk, we discuss the remarkable role of position dependent damping in determining the parametric regions of symmetry breaking in nonlinear ΡΤ -symmetric systems. We illustrate the nature of ΡΤ-symmetry preservation and breaking with reference to a remarkable integrable scalar nonlinear system. In the two dimensional cases of such position dependent damped systems, we unveil the existence of a class of novel bi-ΡΤ -symmetric systems which have two fold ΡΤ symmetries. We discuss the dynamics of these systems and show how symmetry breaking occurs, that is whether the symmetry breaking of the two ΡΤ symmetries occurs in pair or occurs one by one. The addition of linear damping in these nonlinearly damped systems induces competition between the two types of damping. This competition results in a ΡΤ phase transition in which the ΡΤ symmetry is broken for lower loss/gain strength and is restored by increasing the loss/gain strength. We also show that by properly designing the form of the position dependent damping, we can tailor the ΡΤ-symmetric regions of the system. (author)

  11. Time reversal imaging, Inverse problems and Adjoint Tomography}

    Science.gov (United States)

    Montagner, J.; Larmat, C. S.; Capdeville, Y.; Kawakatsu, H.; Fink, M.

    2010-12-01

    With the increasing power of computers and numerical techniques (such as spectral element methods), it is possible to address a new class of seismological problems. The propagation of seismic waves in heterogeneous media is simulated more and more accurately and new applications developed, in particular time reversal methods and adjoint tomography in the three-dimensional Earth. Since the pioneering work of J. Claerbout, theorized by A. Tarantola, many similarities were found between time-reversal methods, cross-correlations techniques, inverse problems and adjoint tomography. By using normal mode theory, we generalize the scalar approach of Draeger and Fink (1999) and Lobkis and Weaver (2001) to the 3D- elastic Earth, for theoretically understanding time-reversal method on global scale. It is shown how to relate time-reversal methods on one hand, with auto-correlations of seismograms for source imaging and on the other hand, with cross-correlations between receivers for structural imaging and retrieving Green function. Time-reversal methods were successfully applied in the past to acoustic waves in many fields such as medical imaging, underwater acoustics, non destructive testing and to seismic waves in seismology for earthquake imaging. In the case of source imaging, time reversal techniques make it possible an automatic location in time and space as well as the retrieval of focal mechanism of earthquakes or unknown environmental sources . We present here some applications at the global scale of these techniques on synthetic tests and on real data, such as Sumatra-Andaman (Dec. 2004), Haiti (Jan. 2010), as well as glacial earthquakes and seismic hum.

  12. Dynamical study of symmetries: breaking and restauration

    International Nuclear Information System (INIS)

    Schuck, P.

    1986-09-01

    First symmetry breaking (spontaneous) is explained and the physical implication discussed for infinite systems. The relation with phase transitions is indicated. Then the specific aspects of symmetry breaking in finite systems is treated and illustrated in detail for the case of translational invariance with the help of an oversimplified but exactly solvable model. The method of projection (restauration of symmetry) is explained for the static case and also applied to the model. Symmetry breaking in the dynamical case and for instance the notion of a soft mode responsible for the symmetry breaking is discussed in the case of superfluidity and another exactly solvable model is introduced. The Goldstone mode is treated in detail. Some remarks on analogies with the breaking of chiral symmetry are made. Some recent developments in the theory of symmetry restauration are briefly outlined [fr

  13. Pair breaking and density of states in disordered superconductors

    International Nuclear Information System (INIS)

    Weinkauf, A.; Zittartz, J.

    1975-01-01

    It is shown that pair breaking occurs in a disordered superconductor due to spatial variations of the order parameter, although the system is time reversal invariant. The pair breaking effect is reflected by the occurence of some interesting fine structure in the one particle density of states. Discrete bound states and split-off impurity bands show up in the single impurity case and for very dilute alloys, respectively. For finite alloy concentrations the calculations are done within the CPA. Although principally important, the fine structure is concentrated in an energy range too narrow to be detected experimentally. (orig.) [de

  14. Chiral symmetry and chiral-symmetry breaking

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1982-12-01

    These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed

  15. Nonrandom distribuion of chromosome breaks in cultured lymphocytes of normal subjects

    Energy Technology Data Exchange (ETDEWEB)

    Ayme, S.; Mattei, J.F.; Mattei, M.G.; Aurran, Y.; Giraud, F.

    1976-02-29

    Breakpoint distribution was studied from cultured lymphocytes on 7653 metaphases from 524 subjects whose karyotypes were normal. The mean break rate was 5% in both sexes. The frequency increased significantly after 40 years and varied during the year. The location of the breaks was very different from the expected random distribution. The break frequency for each chromosome was different according to the type of break (chromatid, simple chromosomal and chromosomal involving rearrangements). The location of the breaks was also studied according to the type of band and with respect to the centromere. A comparison between spontaneous breaks, x-ray induced breaks, breaks in Fanconi's anemia and in congenital rearrangements, show very significant differences.

  16. Spontaneous symmetry breaking in the $S_3$-symmetric scalar sector

    CERN Document Server

    Emmanuel-Costa, D.; Osland, P.; Rebelo, M.N.

    2016-02-23

    We present a detailed study of the vacua of the $S_3$-symmetric three-Higgs-doublet potential, specifying the region of parameters where these minimisation solutions occur. We work with a CP conserving scalar potential and analyse the possible real and complex vacua with emphasis on the cases in which the CP symmetry can be spontaneously broken. Results are presented both in the reducible-representation framework of Derman, and in the irreducible-representation framework. Mappings between these are given. Some of these implementations can in principle accommodate dark matter and for that purpose it is important to identify the residual symmetries of the potential after spontaneous symmetry breakdown. We are also concerned with constraints from vacuum stability.

  17. Spontaneous parity violation and minimal Higgs models

    International Nuclear Information System (INIS)

    Chavez, H.; Martins Simoes, J.A.

    2007-01-01

    In this paper we present a model for the spontaneous breaking of parity with two Higgs doublets and two neutral Higgs singlets which are even and odd under D-parity. The condition υ R >>υ L can be satisfied without introducing bidoublets, and it is induced by the breaking of D-parity through the vacuum expectation value of the odd Higgs singlet. Examples of left-right symmetric and mirror fermions models in grand unified theories are presented. (orig.)

  18. Remote Whispering Applying Time Reversal

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Brian Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-16

    The purpose of this project was to explore the use of time reversal technologies as a means for communication to a targeted individual or location. The idea is to have the privacy of whispering in one’s ear, but to do this remotely from loudspeakers not located near the target. Applications of this work include communicating with hostages and survivors in rescue operations, communicating imaging and operational conditions in deep drilling operations, monitoring storage of spent nuclear fuel in storage casks without wires, or clandestine activities requiring signaling between specific points. This technology provides a solution in any application where wires and radio communications are not possible or not desired. It also may be configured to self calibrate on a regular basis to adjust for changing conditions. These communications allow two people to converse with one another in real time, converse in an inaudible frequency range or medium (i.e. using ultrasonic frequencies and/or sending vibrations through a structure), or send information for a system to interpret (even allowing remote control of a system using sound). The time reversal process allows one to focus energy to a specific location in space and to send a clean transmission of a selected signal only to that location. In order for the time reversal process to work, a calibration signal must be obtained. This signal may be obtained experimentally using an impulsive sound, a known chirp signal, or other known signals. It may also be determined from a numerical model of a known environment in which the focusing is desired or from passive listening over time to ambient noise.

  19. Spontaneous breaking of conformal invariance and trace anomaly matching

    International Nuclear Information System (INIS)

    Schwimmer, A.; Theisen, S.

    2011-01-01

    We argue that when conformal symmetry is spontaneously broken the trace anomalies in the broken and unbroken phases are matched. This puts strong constraints on the various couplings of the dilaton. Using the uniqueness of the effective action for the Goldstone supermultiplet for broken N=1 superconformal symmetry the dilaton effective action is calculated.

  20. Time reversal technique for gas leakage detection.

    Science.gov (United States)

    Maksimov, A O; Polovinka, Yu A

    2015-04-01

    The acoustic remote sensing of subsea gas leakage traditionally uses sonars as active acoustic sensors and hydrophones picking up the sound generated by a leak as passive sensors. When gas leaks occur underwater, bubbles are produced and emit sound at frequencies intimately related to their sizes. The experimental implementation of an acoustic time-reversal mirror (TRM) is now well established in underwater acoustics. In the basic TRM experiment, a probe source emits a pulse that is received on an array of sensors, time reversed, and re-emitted. After time reversal, the resulting field focuses back at the probe position. In this study, a method for enhancing operation of the passive receiving system has been proposed by using it in the regime of TRM. Two factors, the local character of the acoustic emission signal caused by the leakage and a resonant nature of the bubble radiation at their birth, make particularly effective scattering with the conjugate wave (CW). Analytical calculations are performed for the scattering of CW wave on a single bubble when CW is formed by bubble birthing wail received on an array, time reversed, and re-emitted. The quality of leakage detection depends on the spatio-temporal distribution of ambient noise.

  1. Spontaneous Wave Generation from Submesoscale Fronts and Filaments

    Science.gov (United States)

    Shakespeare, C. J.; Hogg, A.

    2016-02-01

    Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

  2. Symmetry-breaking and high-spin states

    Energy Technology Data Exchange (ETDEWEB)

    Khanna, F C [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; [TRIUMF, Vancouver, BC (Canada)

    1992-08-01

    Spontaneous symmetry breaking in nuclear matter would require Nambu-Goldstone bosons in the system. A model calculation gives the nature of these excitations. In finite nuclei the excitations will be a mixture of rotational, surface vibrations and pseudo-Goldstone bosons. A search for such excitations would be fruitful. (author). 5 refs.

  3. Underwater Time Service and Synchronization Based on Time Reversal Technique

    Science.gov (United States)

    Lu, Hao; Wang, Hai-bin; Aissa-El-Bey, Abdeldjalil; Pyndiah, Ramesh

    2010-09-01

    Real time service and synchronization are very important to many underwater systems. But the time service and synchronization in existence cannot work well due to the multi-path propagation and random phase fluctuation of signals in the ocean channel. The time reversal mirror technique can realize energy concentration through self-matching of the ocean channel and has very good spatial and temporal focusing properties. Based on the TRM technique, we present the Time Reversal Mirror Real Time service and synchronization (TRMRT) method which can bypass the processing of multi-path on the server side and reduce multi-path contamination on the client side. So TRMRT can improve the accuracy of time service. Furthermore, as an efficient and precise method of time service, TRMRT could be widely used in underwater exploration activities and underwater navigation and positioning systems.

  4. Mirror Symmetry Breaking by Chirality Synchronisation in Liquids and Liquid Crystals of Achiral Molecules.

    Science.gov (United States)

    Tschierske, Carsten; Ungar, Goran

    2016-01-04

    Spontaneous mirror symmetry breaking is an efficient way to obtain homogeneously chiral agents, pharmaceutical ingredients and materials. It is also in the focus of the discussion around the emergence of uniform chirality in biological systems. Tremendous progress has been made by symmetry breaking during crystallisation from supercooled melts or supersaturates solutions and by self-assembly on solid surfaces and in other highly ordered structures. However, recent observations of spontaneous mirror symmetry breaking in liquids and liquid crystals indicate that it is not limited to the well-ordered solid state. Herein, progress in the understanding of a new dynamic mode of symmetry breaking, based on chirality synchronisation of transiently chiral molecules in isotropic liquids and in bicontinuous cubic, columnar, smectic and nematic liquid crystalline phases is discussed. This process leads to spontaneous deracemisation in the liquid state under thermodynamic control, giving rise to long-term stable symmetry-broken fluids, even at high temperatures. These fluids form conglomerates that are capable of extraordinary strong chirality amplification, eventually leading to homochirality and providing a new view on the discussion of emergence of uniform chirality in prebiotic systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Time-Reversal Generation of Rogue Waves

    Science.gov (United States)

    Chabchoub, Amin; Fink, Mathias

    2014-03-01

    The formation of extreme localizations in nonlinear dispersive media can be explained and described within the framework of nonlinear evolution equations, such as the nonlinear Schrödinger equation (NLS). Within the class of exact NLS breather solutions on a finite background, which describe the modulational instability of monochromatic wave trains, the hierarchy of rational solutions localized in both time and space is considered to provide appropriate prototypes to model rogue wave dynamics. Here, we use the time-reversal invariance of the NLS to propose and experimentally demonstrate a new approach to constructing strongly nonlinear localized waves focused in both time and space. The potential applications of this time-reversal approach include remote sensing and motivated analogous experimental analysis in other nonlinear dispersive media, such as optics, Bose-Einstein condensates, and plasma, where the wave motion dynamics is governed by the NLS.

  6. Selection rules for Cooper pairing in two-dimensional interfaces and sheets

    Science.gov (United States)

    Scheurer, Mathias S.; Agterberg, Daniel F.; Schmalian, Jörg

    2017-12-01

    Thin sheets deposited on a substrate and interfaces of correlated materials offer a plethora of routes towards the realization of exotic phases of matter. In these systems, inversion symmetry is broken which strongly affects the properties of possible instabilities—in particular in the superconducting channel. By combining symmetry and energetic arguments, we derive general and experimentally accessible selection rules for Cooper instabilities in noncentrosymmetric systems, which yield necessary and sufficient conditions for spontaneous time-reversal-symmetry breaking at the superconducting transition and constrain the orientation of the triplet vector. We discuss in detail the implications for various different materials. For instance, we conclude that the pairing state in thin layers of Sr2RuO4 must, as opposed to its bulk superconducting state, preserve time-reversal symmetry with its triplet vector being parallel to the plane of the system. All triplet states of this system allowed by the selection rules are predicted to display topological Majorana modes at dislocations or at the edge of the system. Applying our results to the LaAlO3/SrTiO3 heterostructures, we find that while the condensates of the (001) and (110) oriented interfaces must be time-reversal symmetric, spontaneous time-reversal-symmetry breaking can only occur for the less studied (111) interface. We also discuss the consequences for thin layers of URu2Si2 and UPt3 as well as for single-layer FeSe. On a more general level, our considerations might serve as a design principle in the search for time-reversal-symmetry-breaking superconductivity in the absence of external magnetic fields.

  7. Brane Lorentz symmetry from Lorentz breaking in the bulk

    Energy Technology Data Exchange (ETDEWEB)

    Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Carvalho, C [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal)

    2007-05-15

    We propose the mechanism of spontaneous symmetry breaking of a bulk vector field as a way to generate the selection of bulk dimensions invisible to the standard model confined to the brane. By assigning a nonvanishing vacuum value to the vector field, a direction is singled out in the bulk vacuum, thus breaking the bulk Lorentz symmetry. We present the condition for induced Lorentz symmetry on the brane, as phenomenologically required.

  8. Multiples least-squares reverse time migration

    KAUST Repository

    Zhang, Dongliang; Zhan, Ge; Dai, Wei; Schuster, Gerard T.

    2013-01-01

    To enhance the image quality, we propose multiples least-squares reverse time migration (MLSRTM) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. Since each recorded trace is treated

  9. Modeling the safety impacts of driving hours and rest breaks on truck drivers considering time-dependent covariates.

    Science.gov (United States)

    Chen, Chen; Xie, Yuanchang

    2014-12-01

    Driving hours and rest breaks are closely related to driver fatigue, which is a major contributor to truck crashes. This study investigates the effects of driving hours and rest breaks on commercial truck driver safety. A discrete-time logistic regression model is used to evaluate the crash odds ratios of driving hours and rest breaks. Driving time is divided into 11 one hour intervals. These intervals and rest breaks are modeled as dummy variables. In addition, a Cox proportional hazards regression model with time-dependent covariates is used to assess the transient effects of rest breaks, which consists of a fixed effect and a variable effect. Data collected from two national truckload carriers in 2009 and 2010 are used. The discrete-time logistic regression result indicates that only the crash odds ratio of the 11th driving hour is statistically significant. Taking one, two, and three rest breaks can reduce drivers' crash odds by 68%, 83%, and 85%, respectively, compared to drivers who did not take any rest breaks. The Cox regression result shows clear transient effects for rest breaks. It also suggests that drivers may need some time to adjust themselves to normal driving tasks after a rest break. Overall, the third rest break's safety benefit is very limited based on the results of both models. The findings of this research can help policy makers better understand the impact of driving time and rest breaks and develop more effective rules to improve commercial truck safety. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

  10. A BDNF loop-domain mimetic acutely reverses spontaneous apneas and respiratory abnormalities during behavioral arousal in a mouse model of Rett syndrome

    Directory of Open Access Journals (Sweden)

    Miriam Kron

    2014-09-01

    Full Text Available Reduced levels of brain-derived neurotrophic factor (BDNF are thought to contribute to the pathophysiology of Rett syndrome (RTT, a severe neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2. In Mecp2 mutant mice, BDNF deficits have been associated with breathing abnormalities, a core feature of RTT, as well as with synaptic hyperexcitability within the brainstem respiratory network. Application of BDNF can reverse hyperexcitability in acute brainstem slices from Mecp2-null mice, suggesting that therapies targeting BDNF or its receptor, TrkB, could be effective at acute reversal of respiratory abnormalities in RTT. Therefore, we examined the ability of LM22A-4, a small-molecule BDNF loop-domain mimetic and TrkB partial agonist, to modulate synaptic excitability within respiratory cell groups in the brainstem nucleus tractus solitarius (nTS and to acutely reverse abnormalities in breathing at rest and during behavioral arousal in Mecp2 mutants. Patch-clamp recordings in Mecp2-null brainstem slices demonstrated that LM22A-4 decreases excitability at primary afferent synapses in the nTS by reducing the amplitude of evoked excitatory postsynaptic currents and the frequency of spontaneous and miniature excitatory postsynaptic currents. In vivo, acute treatment of Mecp2-null and -heterozygous mutants with LM22A-4 completely eliminated spontaneous apneas in resting animals, without sedation. Moreover, we demonstrate that respiratory dysregulation during behavioral arousal, a feature of human RTT, is also reversed in Mecp2 mutants by acute treatment with LM22A-4. Together, these data support the hypothesis that reduced BDNF signaling and respiratory dysfunction in RTT are linked, and establish the proof-of-concept that treatment with a small-molecule structural mimetic of a BDNF loop domain and a TrkB partial agonist can acutely reverse abnormal breathing at rest and in response to

  11. The Ku Heterodimer and the Metabolism of Single-Ended DNA Double-Strand Breaks

    NARCIS (Netherlands)

    A. Balestrini (Alessia); D. Ristic (Dejan); I. Dionne (Isabelle); X.Z. Liu (Xiao); C. Wyman (Claire); R.J. Wellinger (Raymund); J.H.J. Petrini (John)

    2013-01-01

    textabstractSingle-ended double-strand breaks (DSBs) are a common form of spontaneous DNA break, generated when the replisome encounters a discontinuity in the DNA template. Given their prevalence, understanding the mechanisms governing the fate(s) of single-ended DSBs is important. We describe the

  12. Time reversibility, computer simulation, algorithms, chaos

    CERN Document Server

    Hoover, William Graham

    2012-01-01

    A small army of physicists, chemists, mathematicians, and engineers has joined forces to attack a classic problem, the "reversibility paradox", with modern tools. This book describes their work from the perspective of computer simulation, emphasizing the author's approach to the problem of understanding the compatibility, and even inevitability, of the irreversible second law of thermodynamics with an underlying time-reversible mechanics. Computer simulation has made it possible to probe reversibility from a variety of directions and "chaos theory" or "nonlinear dynamics" has supplied a useful vocabulary and a set of concepts, which allow a fuller explanation of irreversibility than that available to Boltzmann or to Green, Kubo and Onsager. Clear illustration of concepts is emphasized throughout, and reinforced with a glossary of technical terms from the specialized fields which have been combined here to focus on a common theme. The book begins with a discussion, contrasting the idealized reversibility of ba...

  13. Polariton Chimeras: Bose-Einstein Condensates with Intrinsic Chaoticity and Spontaneous Long-Range Ordering

    Science.gov (United States)

    Gavrilov, S. S.

    2018-01-01

    The system of cavity polaritons driven by a plane electromagnetic wave is found to undergo the spontaneous breaking of spatial symmetry, which results in a lifted phase locking with respect to the driving field and, consequently, in the possibility of internal ordering. In particular, periodic spin and intensity patterns arise in polariton wires; they exhibit strong long-range order and can serve as media for signal transmission. Such patterns have the properties of dynamical chimeras: they are formed spontaneously in perfectly homogeneous media and can be partially chaotic. The reported new mechanism of chimera formation requires neither time-delayed feedback loops nor nonlocal interactions.

  14. Factors that influence the timing of spontaneous labor at term.

    Science.gov (United States)

    Fogleman, Kelly A; Herring, Amy H; Kaczor, Diane; Pusek, Susan N; Jo, Hyejin; Thorp, John M

    2007-11-01

    Whether pre-term birth culminates as a result of a de novo pathologic process or is more simply early activation of physiologic mechanisms is unknown. Exploration of the onset of labor in term women with classical risk factors for early delivery might provide insights into the mechanisms leading to pre-term birth. This study examines whether sociodemographic factors known to increase the risk of pre-term birth also affect the length of term gestations. From a large prospective cohort composed of women delivering from 1995-2000, a sample was selected of 441 women from Central North Carolina, US, who delivered singletons after 37 weeks gestation. An algorithm was designed to identify induced labors and gestational age was censored at the time of induction. Gestational age was assigned by sonography and menstrual dating. Data were analysed using the Cox proportional hazards model. The main outcome measure was time to spontaneous labor. Women with 12 years of education had longer periods of gestation than women with less than 12 years of education, HR = 0.57 [0.39, 0.84]. Shorter gestational periods were found for women with pre-term premature rupture of membranes (PPROM) in a previous pregnancy, HR = 3.70 [1.60, 8.52], even after adjusting for confounders. Smoking was not associated (p > 0.1) with the timing of labor at term. By studying the timing of spontaneous parturition at term we identified that there is little overlap in risk factors that affect timing of delivery between spontaneous term and pre-term births.

  15. Symmetry breaking and restoration in gauge theories

    International Nuclear Information System (INIS)

    Natale, A.A.

    A review is made of the utilization of the Higgs mechanism in spontaneous symmetry breaking. It is shown that such as ideas came from an analogy with the superconductivity phenomenological theory based on a Ginzburg-Landau lagrangean. The symmetry restoration through the temperature influence is studied. (L.C.) [pt

  16. Recycling Frank: Spontaneous emergence of homochirality in noncatalytic systems

    Science.gov (United States)

    Plasson, Raphaël; Bersini, Hugues; Commeyras, Auguste

    2004-01-01

    In this work, we introduce a prebiotically relevant protometabolic pattern corresponding to an engine of deracemization by using an external energy source. The spontaneous formation of a nonracemic mixture of chiral compounds can be observed in out-of-equilibrium systems via a symmetry-breaking phenomenon. This observation is possible thanks to chirally selective autocatalytic reactions (Frank's model) [Frank, F. C. (1953) Biochim. Biophys. Acta 11, 459–463]. We show that the use of a Frank-like model in a recycled system composed of reversible chemical reactions, rather than the classical irreversible system, allows for the emergence of a synergetic autoinduction from simple reactions, without any autocatalytic or even catalytic reaction. This model is described as a theoretical framework, based on the stereoselective reactivity of preexisting chiral monomeric building blocks (polymerization, epimerization, and depolymerization) maintained out of equilibrium by a continuous energy income, via an activation reaction. It permits the self-conversion of all monomeric subunits into a single chiral configuration. Real prebiotic systems of amino acid derivatives can be described on this basis. They are shown to be able to spontaneously reach a stable nonracemic state in a few centuries. In such systems, the presence of epimerization reactions is no more destructive, but in contrast is the central driving force of the unstabilization of the racemic state. PMID:15548617

  17. Reversal in the Diameter of the Superior Ophthalmic Vein after an Epidural Blood Patch in a Case of Spontaneous Intracranial Hypotension

    International Nuclear Information System (INIS)

    Hsiao, Chen Yu; Tsai, Yuh Feng

    2011-01-01

    Spontaneous intracranial hypotension (SIH) is caused by single or multiple cerebrospinal fluid (CSF) leaks in the spine with the prototypical symptom of postural headache. One of the characteristic MRI features in SIH is intracranial venous engorgement. This report presents a case of SIH with engorgement of the bilateral superior ophthalmic veins (SOVs) which resume their normal diameters by the third day of successful epidural blood patches (EBPs). We define this phenomenon as the 'reversal of the SOV' sign.

  18. Tests of time reversal in neutron-nucleus scattering

    International Nuclear Information System (INIS)

    Bowman, J.D.

    1988-01-01

    Experiments to test time-reversal invariance are discussed. The experiments are based on observables constructed from the momentum and spin vectors of epithermal neutrons and from the spin of an aligned or polarized target. It is shown that the proposed tests are detailed balance tests of time-reversal invariance. The status of the experiments is briefly reviewed. 14 refs., 5 figs

  19. Translational Symmetry Breaking and Gapping of Heavy-Quasiparticle Pocket in URu2Si2

    Science.gov (United States)

    Yoshida, Rikiya; Tsubota, Koji; Ishiga, Toshihiko; Sunagawa, Masanori; Sonoyama, Jyunki; Aoki, Dai; Flouquet, Jacques; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2013-01-01

    URu2Si2 is a uranium compound that exhibits a so-called ‘hidden-order’ transition at ~17.5 K. However, the order parameter of this second-order transition as well as many of its microscopic properties remain unclarified despite considerable research. One of the key questions in this regard concerns the type of spontaneous symmetry breaking occurring at the transition; although rotational symmetry breaking has been detected, it is not clear whether another type of symmetry breaking also occurs. Another key question concerns the property of Fermi-surface gapping in the momentum space. Here we address these key questions by a momentum-dependent observation of electronic states at the transition employing ultrahigh-resolution three-dimensional angle-resolved photoemission spectroscopy. Our results provide compelling evidence of the spontaneous breaking of the lattice's translational symmetry and particle-hole asymmetric gapping of a heavy quasiparticle pocket at the transition. PMID:24084937

  20. Nonlinear Time-Reversal in a Wave Chaotic System

    Science.gov (United States)

    Frazier, Matthew; Taddese, Biniyam; Ott, Edward; Antonsen, Thomas; Anlage, Steven

    2012-02-01

    Time reversal mirrors are particularly simple to implement in wave chaotic systems and form the basis for a new class of sensors [1-3]. These sensors work by applying the quantum mechanical concepts of Loschmidt echo and fidelity decay to classical waves. The sensors make explicit use of time-reversal invariance and spatial reciprocity in a wave chaotic system to remotely measure the presence of small perturbations to the system. The underlying ray chaos increases the sensitivity to small perturbations throughout the volume explored by the waves. We extend our time-reversal mirror to include a discrete element with a nonlinear dynamical response. The initially injected pulse interacts with the nonlinear element, generating new frequency components originating at the element. By selectively filtering for and applying the time-reversal mirror to the new frequency components, we focus a pulse only onto the element, without knowledge of its location. Furthermore, we demonstrate transmission of arbitrary patterns of pulses to the element, creating a targeted communication channel to the exclusion of 'eavesdroppers' at other locations in the system. [1] Appl. Phys. Lett. 95, 114103 (2009) [2] J. Appl. Phys. 108, 1 (2010) [3] Acta Physica Polonica A 112, 569 (2007)

  1. Least squares reverse time migration of controlled order multiples

    Science.gov (United States)

    Liu, Y.

    2016-12-01

    Imaging using the reverse time migration of multiples generates inherent crosstalk artifacts due to the interference among different order multiples. Traditionally, least-square fitting has been used to address this issue by seeking the best objective function to measure the amplitude differences between the predicted and observed data. We have developed an alternative objective function by decomposing multiples into different orders to minimize the difference between Born modeling predicted multiples and specific-order multiples from observational data in order to attenuate the crosstalk. This method is denoted as the least-squares reverse time migration of controlled order multiples (LSRTM-CM). Our numerical examples demonstrated that the LSRTM-CM can significantly improve image quality compared with reverse time migration of multiples and least-square reverse time migration of multiples. Acknowledgments This research was funded by the National Nature Science Foundation of China (Grant Nos. 41430321 and 41374138).

  2. On the membrane paradigm and spontaneous breaking of horizon BMS symmetries

    International Nuclear Information System (INIS)

    Eling, Christopher; Oz, Yaron

    2016-01-01

    We consider a BMS-type symmetry action on isolated horizons in asymptotically flat spacetimes. From the viewpoint of the non-relativistic field theory on a horizon membrane, supertranslations shift the field theory spatial momentum. The latter is related by a Ward identity to the particle number symmetry current and is spontaneously broken. The corresponding Goldstone boson shifts the horizon angular momentum and can be detected quantum mechanically. Similarly, area preserving superrotations are spontaneously broken on the horizon membrane and we identify the corresponding gapless modes. In asymptotically AdS spacetimes we study the BMS-type symmetry action on the horizon in a holographic superfluid dual. We identify the horizon supertranslation Goldstone boson as the holographic superfluid Goldstone mode.

  3. Canonical forms of tensor representations and spontaneous symmetry breaking

    International Nuclear Information System (INIS)

    Cummins, C.J.

    1986-01-01

    An algorithm for constructing canonical forms for any tensor representation of the classical compact Lie groups is given. This method is used to find a complete list of the symmetry breaking patterns produced by Higgs fields in the third-rank antisymmetric representations of U(n), SU(n) and SO(n) for n<=7. A simple canonical form is also given for kth-rank symmetric tensor representations. (author)

  4. Dark matter, baryon asymmetry, and spontaneous B and L breaking

    International Nuclear Information System (INIS)

    Dulaney, Timothy R.; Wise, Mark B.; Perez, Pavel Fileviez

    2011-01-01

    We investigate the dark matter and the cosmological baryon asymmetry in a simple theory where baryon (B) and lepton (L) number are local gauge symmetries that are spontaneously broken. In this model, the cold dark matter candidate is the lightest new field with baryon number and its stability is an automatic consequence of the gauge symmetry. Dark matter annihilation is either through a leptophobic gauge boson whose mass must be below a TeV or through the Higgs boson. Since the mass of the leptophobic gauge boson has to be below the TeV scale, one finds that in the first scenario there is a lower bound on the elastic cross section of about 5x10 -46 cm 2 . Even though baryon number is gauged and not spontaneously broken until the weak scale, a cosmologically acceptable baryon excess is possible. There can be a tension between achieving both the measured baryon excess and the dark matter density.

  5. Recovery from prolonged deep rocuronium-induced neuromuscular blockade: A randomized comparison of sugammadex reversal with spontaneous recovery.

    Science.gov (United States)

    Rahe-Meyer, N; Berger, C; Wittmann, M; Solomon, C; Abels, E A M; Rietbergen, H; Reuter, D A

    2015-07-01

    Deep neuromuscular blockade (NMB) may not always be maintained to the end of surgery and the depth of block may be allowed to gradually diminish over time, particularly if reversal of NMB is not routinely performed. The current study aimed to assess recovery from deep rocuronium-induced NMB with sugammadex compared with placebo, provide data regarding the extent of residual blockade after deep rocuronium-induced NMB (placebo group), and to determine whether complete and reliable recovery could be provided by sugammadex (sugammadex group). This was a randomized, placebo-controlled, safety-assessor-blinded study in adult patients of American Society of Anesthesiologists Class I to III. Patients with clinically relevant kidney or liver insufficiency were excluded. Anesthesia was administered as routinely practiced at each study site. Rocuronium 0.6 mg/kg was administered for intubation, with maintenance doses of 0.1-0.2 mg/kg as needed. After the last rocuronium dose, at deep NMB (target depth 1-2 post-tetanic counts), patients received a single dose of sugammadex 4.0 mg/kg or placebo as randomized. The primary endpoint was time from sugammadex or placebo administration to recovery of the train-of-four (TOF) ratio to 0.9. Safety was assessed through monitoring of adverse events, vital signs and physical examination. Patients were also assessed for evidence of residual or recurrence of NMB. With this design, the study will provide data regarding the extent of residual blockade under these conditions (placebo group), and determine whether complete and reliable recovery could be provided by sugammadex (sugammadex group). Recovery to a TOF ratio of ≥ 0.9 with sugammadex was significantly faster (~ 40 times) than spontaneous recovery: geometric mean (95 % confidence interval) times were 2.2 (1.9-2.5) and 89.8 (80.1-100.7) min, respectively (p sugammadex, with median time to recovery > 1.5 h in the placebo group and one patient taking 4.8 h to achieve a

  6. Predictions of the spontaneous symmetry-breaking theory for visual code completeness and spatial scaling in single-cell learning rules.

    Science.gov (United States)

    Webber, C J

    2001-05-01

    This article shows analytically that single-cell learning rules that give rise to oriented and localized receptive fields, when their synaptic weights are randomly and independently initialized according to a plausible assumption of zero prior information, will generate visual codes that are invariant under two-dimensional translations, rotations, and scale magnifications, provided that the statistics of their training images are sufficiently invariant under these transformations. Such codes span different image locations, orientations, and size scales with equal economy. Thus, single-cell rules could account for the spatial scaling property of the cortical simple-cell code. This prediction is tested computationally by training with natural scenes; it is demonstrated that a single-cell learning rule can give rise to simple-cell receptive fields spanning the full range of orientations, image locations, and spatial frequencies (except at the extreme high and low frequencies at which the scale invariance of the statistics of digitally sampled images must ultimately break down, because of the image boundary and the finite pixel resolution). Thus, no constraint on completeness, or any other coupling between cells, is necessary to induce the visual code to span wide ranges of locations, orientations, and size scales. This prediction is made using the theory of spontaneous symmetry breaking, which we have previously shown can also explain the data-driven self-organization of a wide variety of transformation invariances in neurons' responses, such as the translation invariance of complex cell response.

  7. Lattice QCD with light quark masses: Does chiral symmetry get broken spontaneously

    International Nuclear Information System (INIS)

    Barbour, I.M.; Schierholz, G.; Teper, M.; Gilchrist, J.P.; Schneider, H.

    1983-03-01

    We present a first direct calculation of the properties of QCD for the small quark masses of phenomenological interest without extrapolations. We describe methods specially adapted to invert the fermion matrix at small quark masses. We use these methods to calculate directly on presently used lattice sizes with different boundary conditions. As is to be expected for a finite system, we do not observe spontaneous chiral symmetry breaking. By comparing the results obtained on lattices of different size we see, however, indications that are consistent with eventual spontaneous chiral symmetry breaking in the infinite volume limit. Our calculations underline the importance of using antiperiodic boundary conditions for fermions. (orig.)

  8. The suggestion about the absence of the phase transition, vacuum degeneration, spontaneous symmetry breaking and zero-mass Goldstone-bosons in QFT models of the type gphi4

    International Nuclear Information System (INIS)

    Zastavenko, L.G.

    1979-01-01

    The usual proof of the phase transition existence in the gphi 4 model is considered. (For M 2 >M 0 2 minimum of the effective potential is at phi(0)=0, for M 2 >M 0 2 this minimum is at phi(0)=+-lambda not equal to 0, lambda→+ infinity at M 2 →- infinity). This proof is shown to be wrong, thus suggesting the absence in the model considered of the phase transition, vacuum degeneration, spontaneous symmetry breaking and zero-mass Goldstone-bosons

  9. Using machine learning to identify structural breaks in single-group interrupted time series designs.

    Science.gov (United States)

    Linden, Ariel; Yarnold, Paul R

    2016-12-01

    Single-group interrupted time series analysis (ITSA) is a popular evaluation methodology in which a single unit of observation is being studied, the outcome variable is serially ordered as a time series and the intervention is expected to 'interrupt' the level and/or trend of the time series, subsequent to its introduction. Given that the internal validity of the design rests on the premise that the interruption in the time series is associated with the introduction of the treatment, treatment effects may seem less plausible if a parallel trend already exists in the time series prior to the actual intervention. Thus, sensitivity analyses should focus on detecting structural breaks in the time series before the intervention. In this paper, we introduce a machine-learning algorithm called optimal discriminant analysis (ODA) as an approach to determine if structural breaks can be identified in years prior to the initiation of the intervention, using data from California's 1988 voter-initiated Proposition 99 to reduce smoking rates. The ODA analysis indicates that numerous structural breaks occurred prior to the actual initiation of Proposition 99 in 1989, including perfect structural breaks in 1983 and 1985, thereby casting doubt on the validity of treatment effects estimated for the actual intervention when using a single-group ITSA design. Given the widespread use of ITSA for evaluating observational data and the increasing use of machine-learning techniques in traditional research, we recommend that structural break sensitivity analysis is routinely incorporated in all research using the single-group ITSA design. © 2016 John Wiley & Sons, Ltd.

  10. DNA breaks and repair in interstitial telomere sequences: Influence of chromatin structure

    International Nuclear Information System (INIS)

    Revaud, D.

    2009-06-01

    Interstitial Telomeric Sequences (ITS) are over-involved in spontaneous and radiationinduced chromosome aberrations in chinese hamster cells. We have performed a study to investigate the origin of their instability, spontaneously or after low doses irradiation. Our results demonstrate that ITS have a particular chromatin structure: short nucleotide repeat length, less compaction of the 30 nm chromatin fiber, presence of G-quadruplex structures. These features would modulate breaks production and would favour the recruitment of alternative DNA repair mechanisms, which are prone to produce chromosome aberrations. These pathways could be at the origin of chromosome aberrations in ITS whereas NHEJ and HR Double Strand Break repair pathways are rather required for a correct repair in these regions. (author)

  11. Time reversal and parity tests

    International Nuclear Information System (INIS)

    Terwilliger, K.

    1975-01-01

    A recent review by Henley discusses the present status of Time Reversal and Parity symmetry violations, and comments on the implications for high energy hadron scattering. This note will briefly summarize the situation with particular attention to the sizes of possible effects, relating them to experimental accuracy available or reasonably possible at the ZGS

  12. A Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry

    International Nuclear Information System (INIS)

    Wang Dianfu; Song Heshan

    2005-01-01

    A generalized Yang-Mills model, which contains, besides the vector part V μ , also a scalar part S, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of Nambu-Jona-Lasinio (NJL) mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills model. The combination of the generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  13. Time-reversal and Bayesian inversion

    Science.gov (United States)

    Debski, Wojciech

    2017-04-01

    Probabilistic inversion technique is superior to the classical optimization-based approach in all but one aspects. It requires quite exhaustive computations which prohibit its use in huge size inverse problems like global seismic tomography or waveform inversion to name a few. The advantages of the approach are, however, so appealing that there is an ongoing continuous afford to make the large inverse task as mentioned above manageable with the probabilistic inverse approach. One of the perspective possibility to achieve this goal relays on exploring the internal symmetry of the seismological modeling problems in hand - a time reversal and reciprocity invariance. This two basic properties of the elastic wave equation when incorporating into the probabilistic inversion schemata open a new horizons for Bayesian inversion. In this presentation we discuss the time reversal symmetry property, its mathematical aspects and propose how to combine it with the probabilistic inverse theory into a compact, fast inversion algorithm. We illustrate the proposed idea with the newly developed location algorithm TRMLOC and discuss its efficiency when applied to mining induced seismic data.

  14. Time reversal invariance for a nonlinear scatterer exhibiting contact acoustic nonlinearity

    Science.gov (United States)

    Blanloeuil, Philippe; Rose, L. R. Francis; Veidt, Martin; Wang, Chun H.

    2018-03-01

    The time reversal invariance of an ultrasonic plane wave interacting with a contact interface characterized by a unilateral contact law is investigated analytically and numerically. It is shown analytically that despite the contact nonlinearity, the re-emission of a time reversed version of the reflected and transmitted waves can perfectly recover the original pulse shape, thereby demonstrating time reversal invariance for this type of contact acoustic nonlinearity. With the aid of finite element modelling, the time-reversal analysis is extended to finite-size nonlinear scatterers such as closed cracks. The results show that time reversal invariance holds provided that all the additional frequencies generated during the forward propagation, such as higher harmonics, sub-harmonics and zero-frequency component, are fully included in the retro-propagation. If the scattered waves are frequency filtered during receiving or transmitting, such as through the use of narrowband transducers, the recombination of the time-reversed waves will not exactly recover the original incident wave. This discrepancy due to incomplete time invariance can be exploited as a new method for characterizing damage by defining damage indices that quantify the departure from time reversal invariance. The sensitivity of these damage indices for various crack lengths and contact stress levels is investigated computationally, indicating some advantages of this narrowband approach relative to the more conventional measurement of higher harmonic amplitude, which requires broadband transducers.

  15. The Two-Time Interpretation and Macroscopic Time-Reversibility

    Directory of Open Access Journals (Sweden)

    Yakir Aharonov

    2017-03-01

    Full Text Available The two-state vector formalism motivates a time-symmetric interpretation of quantum mechanics that entails a resolution of the measurement problem. We revisit a post-selection-assisted collapse model previously suggested by us, claiming that unlike the thermodynamic arrow of time, it can lead to reversible dynamics at the macroscopic level. In addition, the proposed scheme enables us to characterize the classical-quantum boundary. We discuss the limitations of this approach and its broad implications for other areas of physics.

  16. A time reversal damage imaging method for structure health monitoring using Lamb waves

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Cao Ya-Ping; Sun Xiu-Li; Chen Xian-Hua; Yu Jian-Bo

    2010-01-01

    This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably

  17. Large eddy simulation of breaking waves

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Deigaard, Rolf

    2001-01-01

    A numerical model is used to simulate wave breaking, the large scale water motions and turbulence induced by the breaking process. The model consists of a free surface model using the surface markers method combined with a three-dimensional model that solves the flow equations. The turbulence....... The incoming waves are specified by a flux boundary condition. The waves are approaching in the shore-normal direction and are breaking on a plane, constant slope beach. The first few wave periods are simulated by a two-dimensional model in the vertical plane normal to the beach line. The model describes...... the steepening and the overturning of the wave. At a given instant, the model domain is extended to three dimensions, and the two-dimensional flow field develops spontaneously three-dimensional flow features with turbulent eddies. After a few wave periods, stationary (periodic) conditions are achieved...

  18. Adiabatic, chaotic and quasi-adiabatic charged particle motion in two-dimensional magnetic field reversals

    International Nuclear Information System (INIS)

    Buechner, J.M.

    1989-01-01

    For a number of problems in the Plasma Astrophysics it is necessary to know the laws, which govern the non adiabatic charged particle dynamics in strongly curves magnetic field reversals. These are, e.q., the kinetic theory of the microscopic and macroscopicstability of current sheets in collionless plasma, of microturbulence, causing anomalous resistivity and dissipating currents, the problem of spontaneous reconnection, the formation of non Maxwellian distribution functions, particle acceleration and the use of particles as a diagnostic tool ('tracers'). To find such laws we derived from the differential equations of motion discrete mappings. These mappings allow an investigation of the motion after the break down of the adiabaticity of the magnetic moment. (author). 32 refs.; 5 figs.; 1 tab

  19. Least-squares reverse time migration of multiples

    KAUST Repository

    Zhang, Dongliang; Schuster, Gerard T.

    2013-01-01

    The theory of least-squares reverse time migration of multiples (RTMM) is presented. In this method, least squares migration (LSM) is used to image free-surface multiples where the recorded traces are used as the time histories of the virtual

  20. Dopamine Attenuates Ketamine-Induced Neuronal Apoptosis in the Developing Rat Retina Independent of Early Synchronized Spontaneous Network Activity.

    Science.gov (United States)

    Dong, Jing; Gao, Lingqi; Han, Junde; Zhang, Junjie; Zheng, Jijian

    2017-07-01

    Deprivation of spontaneous rhythmic electrical activity in early development by anesthesia administration, among other interventions, induces neuronal apoptosis. However, it is unclear whether enhancement of neuronal electrical activity attenuates neuronal apoptosis in either normal development or after anesthesia exposure. The present study investigated the effects of dopamine, an enhancer of spontaneous rhythmic electrical activity, on ketamine-induced neuronal apoptosis in the developing rat retina. TUNEL and immunohistochemical assays indicated that ketamine time- and dose-dependently aggravated physiological and ketamine-induced apoptosis and inhibited early-synchronized spontaneous network activity. Dopamine administration reversed ketamine-induced neuronal apoptosis, but did not reverse the inhibitory effects of ketamine on early synchronized spontaneous network activity despite enhancing it in controls. Blockade of D1, D2, and A2A receptors and inhibition of cAMP/PKA signaling partially antagonized the protective effect of dopamine against ketamine-induced apoptosis. Together, these data indicate that dopamine attenuates ketamine-induced neuronal apoptosis in the developing rat retina by activating the D1, D2, and A2A receptors, and upregulating cAMP/PKA signaling, rather than through modulation of early synchronized spontaneous network activity.

  1. Energy drift in reversible time integration

    International Nuclear Information System (INIS)

    McLachlan, R I; Perlmutter, M

    2004-01-01

    Energy drift is commonly observed in reversible integrations of systems of molecular dynamics. We show that this drift can be modelled as a diffusion and that the typical energy error after time T is O(√T). (letter to the editor)

  2. Spontaneous Hall effect in a chiral p-wave superconductor

    Science.gov (United States)

    Furusaki, Akira; Matsumoto, Masashige; Sigrist, Manfred

    2001-08-01

    In a chiral superconductor with broken time-reversal symmetry a ``spontaneous Hall effect'' may be observed. We analyze this phenomenon by taking into account the surface properties of a chiral superconductor. We identify two main contributions to the spontaneous Hall effect. One contribution originates from the Bernoulli (or Lorentz) force due to spontaneous currents running along the surfaces of the superconductor. The other contribution has a topological origin and is related to the intrinsic angular momentum of Cooper pairs. The latter can be described in terms of a Chern-Simons-like term in the low-energy field theory of the superconductor and has some similarities with the quantum Hall effect. The spontaneous Hall effect in a chiral superconductor is, however, nonuniversal. Our analysis is based on three approaches to the problem: a self-consistent solution of the Bogoliubov-de Gennes equation, a generalized Ginzburg-Landau theory, and a hydrodynamic formulation. All three methods consistently lead to the same conclusion that the spontaneous Hall resistance of a two-dimensional superconducting Hall bar is of order h/(ekFλ)2, where kF is the Fermi wave vector and λ is the London penetration depth; the Hall resistance is substantially suppressed from a quantum unit of resistance. Experimental issues in measuring this effect are briefly discussed.

  3. Spontaneous De-Icing Phenomena on Extremely Cold Surfaces

    Science.gov (United States)

    Song, Dong; Choi, Chang-Hwan

    2017-11-01

    Freezing of droplets on cold surfaces is universal phenomenon, while the mechanisms are still inadequately understood. Here we report spontaneous de-icing phenomena of an impacting droplet which occur on extreme cold surfaces. When a droplet impacts on cold surfaces lower than -80°, it takes more than two times longer for the droplet to freeze than the ones at -50°. Moreover, the frozen droplet below -80° breaks up into several large parts spontaneously in the end. When a droplet impacts on the extreme cold surfaces, evaporation and condensation occur immediately as the droplet approaches the substrate. A thick layer of frost forms between the droplet and substrate, decreasing the contact area of the droplet with substrate. It leads to impede the heat transfer and hence extends the freezing time significantly. On the extremely cold substrate, the droplet freezes from the center to the edge area, in contrast to a typical case freezing from the bottom to the top. This novel from-center-to-edge freezing process changes the internal tension of the frozen droplet and results in the instantaneous breakup and release eventually, which can be taken advantage of for effective deicing mechanisms.

  4. Theta, time reversal and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Gaiotto, Davide [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Kapustin, Anton [Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States); Komargodski, Zohar [Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 76100 (Israel); Seiberg, Nathan [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States)

    2017-05-17

    SU(N) gauge theory is time reversal invariant at θ=0 and θ=π. We show that at θ=π there is a discrete ’t Hooft anomaly involving time reversal and the center symmetry. This anomaly leads to constraints on the vacua of the theory. It follows that at θ=π the vacuum cannot be a trivial non-degenerate gapped state. (By contrast, the vacuum at θ=0 is gapped, non-degenerate, and trivial.) Due to the anomaly, the theory admits nontrivial domain walls supporting lower-dimensional theories. Depending on the nature of the vacuum at θ=π, several phase diagrams are possible. Assuming area law for space-like loops, one arrives at an inequality involving the temperatures at which CP and the center symmetry are restored. We also analyze alternative scenarios for SU(2) gauge theory. The underlying symmetry at θ=π is the dihedral group of 8 elements. If deconfined loops are allowed, one can have two O(2)-symmetric fixed points. It may also be that the four-dimensional theory around θ=π is gapless, e.g. a Coulomb phase could match the underlying anomalies.

  5. Theta, time reversal and temperature

    International Nuclear Information System (INIS)

    Gaiotto, Davide; Kapustin, Anton; Komargodski, Zohar; Seiberg, Nathan

    2017-01-01

    SU(N) gauge theory is time reversal invariant at θ=0 and θ=π. We show that at θ=π there is a discrete ’t Hooft anomaly involving time reversal and the center symmetry. This anomaly leads to constraints on the vacua of the theory. It follows that at θ=π the vacuum cannot be a trivial non-degenerate gapped state. (By contrast, the vacuum at θ=0 is gapped, non-degenerate, and trivial.) Due to the anomaly, the theory admits nontrivial domain walls supporting lower-dimensional theories. Depending on the nature of the vacuum at θ=π, several phase diagrams are possible. Assuming area law for space-like loops, one arrives at an inequality involving the temperatures at which CP and the center symmetry are restored. We also analyze alternative scenarios for SU(2) gauge theory. The underlying symmetry at θ=π is the dihedral group of 8 elements. If deconfined loops are allowed, one can have two O(2)-symmetric fixed points. It may also be that the four-dimensional theory around θ=π is gapless, e.g. a Coulomb phase could match the underlying anomalies.

  6. The geometric role of symmetry breaking in gravity

    International Nuclear Information System (INIS)

    Wise, Derek K

    2012-01-01

    In gravity, breaking symmetry from a group G to a group H plays the role of describing geometry in relation to the geometry of the homogeneous space G/H. The deep reason for this is Cartan's 'method of equivalence,' giving, in particular, an exact correspondence between metrics and Cartan connections. I argue that broken symmetry is thus implicit in any gravity theory, for purely geometric reasons. As an application, I explain how this kind of thinking gives a new approach to Hamiltonian gravity in which an observer field spontaneously breaks Lorentz symmetry and gives a Cartan connection on space.

  7. Parity- and time-reversal-violating moments of light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Vries, Jordy de, E-mail: devries@kvi.nl [KVI, theory group (Netherlands)

    2013-03-15

    I present the calculation of parity- and time-reversal-violating moments of the nucleon and light nuclei, originating from the QCD {theta}-bar term and effective dimension-six operators. By applying chiral effective field theory these calculations are performed in a unified framework. I argue that measurements of a few light-nuclear electric dipole moments would shed light on the mechanism of parity and time-reversal violation.

  8. Spin-rotation symmetry breaking and triplet superconducting state in doped topological insulator CuxBi2Se3

    Science.gov (United States)

    Zheng, Guo-Qing

    Spontaneous symmetry breaking is an important concept for understanding physics ranging from the elementary particles to states of matter. For example, the superconducting state breaks global gauge symmetry, and unconventional superconductors can break additional symmetries. In particular, spin rotational symmetry is expected to be broken in spin-triplet superconductors. However, experimental evidence for such symmetry breaking has not been obtained so far in any candidate compounds. We report 77Se nuclear magnetic resonance measurements which showed that spin rotation symmetry is spontaneously broken in the hexagonal plane of the electron-doped topological insulator Cu0.3Bi2Se3 below the superconducting transition temperature Tc =3.4 K. Our results not only establish spin-triplet (odd parity) superconductivity in this compound, but also serve to lay a foundation for the research of topological superconductivity (Ref.). We will also report the doping mechanism and superconductivity in Sn1-xInxTe.

  9. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2017-03-08

    We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

  10. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai; Schuster, Gerard T.

    2017-01-01

    We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

  11. Cooperation and competition between two symmetry breakings in a coupled ratchet

    Science.gov (United States)

    Li, Chen-Pu; Chen, Hong-Bin; Fan, Hong; Xie, Ge-Ying; Zheng, Zhi-Gang

    2018-03-01

    We investigate the collective mechanism of coupled Brownian motors in a flashing ratchet in the presence of coupling symmetry breaking and space symmetry breaking. The dependences of directed current on various parameters are extensively studied in terms of numerical simulations and theoretical analysis. Reversed motion can be achieved by modulating multiple parameters including the spatial asymmetry coefficient, the coupling asymmetry coefficient, the coupling free length and the coupling strength. The dynamical mechanism of these transport properties can be reasonably explained by the effective potential theory and the cooperation or competition between two symmetry breakings. Moreover, adjusting the Gaussian white noise intensity, which can induce weak reversed motion under certain condition, can optimize and manipulate the directed transport of the ratchet system.

  12. Dynamics of symmetry breaking during quantum real-time evolution in a minimal model system.

    Science.gov (United States)

    Heyl, Markus; Vojta, Matthias

    2014-10-31

    One necessary criterion for the thermalization of a nonequilibrium quantum many-particle system is ergodicity. It is, however, not sufficient in cases where the asymptotic long-time state lies in a symmetry-broken phase but the initial state of nonequilibrium time evolution is fully symmetric with respect to this symmetry. In equilibrium, one particular symmetry-broken state is chosen as a result of an infinitesimal symmetry-breaking perturbation. From a dynamical point of view the question is: Can such an infinitesimal perturbation be sufficient for the system to establish a nonvanishing order during quantum real-time evolution? We study this question analytically for a minimal model system that can be associated with symmetry breaking, the ferromagnetic Kondo model. We show that after a quantum quench from a completely symmetric state the system is able to break its symmetry dynamically and discuss how these features can be observed experimentally.

  13. Concerning tests of time-reversal invariance via the polarization-analyzing power equality

    International Nuclear Information System (INIS)

    Conzett, H.E.

    1982-01-01

    Previous tests of time-reversal invariance via comparisons of polarizations and analyzing powers in nuclear scattering have been examined. It is found that all of these comparisons fail as adequate tests of time-reversal invariance either because of a lack of experimental precision or the lack of sensitivity to any time-reversal symmetry violation

  14. Time reversal in polarized neutron decay: the emiT experiment

    CERN Document Server

    Jones, G L; Anaya, J M; Bowles, T J; Chupp, T E; Coulter, K P; Dewey, M S; Freedman, S J; Fujikawa, B K; García, A; Greene, G L; Hwang, S R; Lising, L J; Mumm, H P; Nico, J S; Robertson, R G H; Steiger, T D; Teasdale, W A; Thompson, A K; Wasserman, E G; Wietfeldt, F E; Wilkerson, J F

    2000-01-01

    The standard electro-weak model predicts negligible violation of time-reversal invariance in light quark processes. We report on an experimental test of time-reversal invariance in the beta decay of polarized neutrons as a search for physics beyond the standard model. The emiT collaboration has measured the time-reversal-violating triple-correlation in neutron beta decay between the neutron spin, electron momentum, and neutrino momentum often referred to as the D coefficient. The first run of the experiment produced 14 million events which are currently being analyzed. However, a second run with improved detectors should provide greater statistical precision and reduced systematic uncertainties.

  15. Reversal of Hartmann's procedure following acute diverticulitis: is timing everything?

    LENUS (Irish Health Repository)

    Fleming, Fergal J

    2012-02-01

    BACKGROUND: Patients who undergo a Hartmann\\'s procedure may not be offered a reversal due to concerns over the morbidity of the second procedure. The aims of this study were to examine the morbidity post reversal of Hartmann\\'s procedure. METHODS: Patients who underwent a Hartmann\\'s procedure for acute diverticulitis (Hinchey 3 or 4) between 1995 and 2006 were studied. Clinical factors including patient comorbidities were analysed to elucidate what preoperative factors were associated with complications following reversal of Hartmann\\'s procedure. RESULTS: One hundred and ten patients were included. Median age was 70 years and 56% of the cohort were male (n = 61). The mortality and morbidity rate for the acute presentation was 7.3% (n = 8) and 34% (n = 37) respectively. Seventy six patients (69%) underwent a reversal at a median of 7 months (range 3-22 months) post-Hartmann\\'s procedure. The complication rate in the reversal group was 25% (n = 18). A history of current smoking (p = 0.004), increasing time to reversal (p = 0.04) and low preoperative albumin (p = 0.003) were all associated with complications following reversal. CONCLUSIONS: Reversal of Hartmann\\'s procedure can be offered to appropriately selected patients though with a significant (25%) morbidity rate. The identification of potential modifiable factors such as current smoking, prolonged time to reversal and low preoperative albumin may allow optimisation of such patients preoperatively.

  16. Acceleration of Convergence to Equilibrium in Markov Chains by Breaking Detailed Balance

    Science.gov (United States)

    Kaiser, Marcus; Jack, Robert L.; Zimmer, Johannes

    2017-07-01

    We analyse and interpret the effects of breaking detailed balance on the convergence to equilibrium of conservative interacting particle systems and their hydrodynamic scaling limits. For finite systems of interacting particles, we review existing results showing that irreversible processes converge faster to their steady state than reversible ones. We show how this behaviour appears in the hydrodynamic limit of such processes, as described by macroscopic fluctuation theory, and we provide a quantitative expression for the acceleration of convergence in this setting. We give a geometrical interpretation of this acceleration, in terms of currents that are antisymmetric under time-reversal and orthogonal to the free energy gradient, which act to drive the system away from states where (reversible) gradient-descent dynamics result in slow convergence to equilibrium.

  17. The spontaneous breakdown of chiral symmetry in QCD

    International Nuclear Information System (INIS)

    Yoshida, K.

    1980-02-01

    It is suggested that the usual path integral representation of Euclidean vacuum amplitude (tunneling amplitude) in QCD must be supplemented by the explicit boundary condition corresponding to the spontaneous breaking of chiral SU(N) x SU(N). Adopting the trial wave function introduced by Nambu and Jona-Lasinio, one sees that such a path integral automatically breaks also the additional chiral U(1) symmetry of massless quarks. The catastrophe of semi-classical approach to QCD and 'U(1) problem' would be avoided in this way and one has, in principle, a better starting point for the self-consistent calculation

  18. Radiatively induced breaking of conformal symmetry in a superpotential

    International Nuclear Information System (INIS)

    Arbuzov, A.B.; Cirilo-Lombardo, D.J.

    2016-01-01

    Radiatively induced symmetry breaking is considered for a toy model with one scalar and one fermion field unified in a superfield. It is shown that the classical quartic self-interaction of the superfield possesses a quantum infrared singularity. Application of the Coleman–Weinberg mechanism for effective potential leads to the appearance of condensates and masses for both scalar and fermion components. That induces a spontaneous breaking of the initial classical symmetries: the supersymmetry and the conformal one. The energy scales for the scalar and fermion condensates appear to be of the same order, while the renormalization scale is many orders of magnitude higher. A possibility to relate the considered toy model to conformal symmetry breaking in the Standard Model is discussed.

  19. Consistency of Trend Break Point Estimator with Underspecified Break Number

    Directory of Open Access Journals (Sweden)

    Jingjing Yang

    2017-01-01

    Full Text Available This paper discusses the consistency of trend break point estimators when the number of breaks is underspecified. The consistency of break point estimators in a simple location model with level shifts has been well documented by researchers under various settings, including extensions such as allowing a time trend in the model. Despite the consistency of break point estimators of level shifts, there are few papers on the consistency of trend shift break point estimators in the presence of an underspecified break number. The simulation study and asymptotic analysis in this paper show that the trend shift break point estimator does not converge to the true break points when the break number is underspecified. In the case of two trend shifts, the inconsistency problem worsens if the magnitudes of the breaks are similar and the breaks are either both positive or both negative. The limiting distribution for the trend break point estimator is developed and closely approximates the finite sample performance.

  20. When Is the Optimal Timing of the Surgical Treatment for Secondary Spontaneous Pneumothorax?

    Science.gov (United States)

    Jeon, Hyun Woo; Kim, Young-Du; Choi, Si Young; Park, Jae Kil

    2017-01-01

    Objectives  The definition of spontaneous pneumothorax is accumulation of air in the pleural space, resulting in dyspnea or chest pain. Unlike primary spontaneous pneumothorax, secondary pneumothorax can be a life-threatening condition and spontaneous healing rate is uncommon. Although surgery is the most effective treatment modality for pneumothorax, surgical management and timing is difficult where there is underlying lung disease and/or medical comorbidities. Prolonged air leakage increases the morbidity and mortality in thoracic surgery. We hypothesized that duration of air leakage before operation may lead to increase in complications. Methods  This study is a retrospective review of 155 consecutive patients with air leakage who underwent bullectomy for secondary spontaneous pneumothorax from January 2005 to July 2013. The patients were divided according to the duration of preoperative air leakage. The patients were followed-up until the time of last visit or death. Postoperative morbidity and mortality were assessed and the risk factors for complications were analyzed. Results  The median age was 65 years (range, 52-88) with male predominance (96.13%). The median duration of preoperative air leakage was 6 days (range, 1-30). The median surgery time was 90 minutes (range, 25-300) and median hospital stay after operation was 7 days (range, 3-75). Postoperative complications occurred in 38 patients (24.52%) and postoperative recurrence was shown to have occurred in 8 patients (5.16%). With multivariate analysis, risk factors for postoperative complications were: underlying interstitial lung disease and air leakage > 5 days before operation. Conclusion  Persistent air leakage was a major surgical indication for pneumothorax. Early surgical treatment reduced postoperative complications for secondary spontaneous pneumothorax. Georg Thieme Verlag KG Stuttgart · New York.

  1. Single-mode Laser by Parity-time Symmetry Breaking

    Science.gov (United States)

    2014-11-21

    solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and

  2. Fermion systems in discrete space-time

    International Nuclear Information System (INIS)

    Finster, Felix

    2007-01-01

    Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure

  3. Fermion systems in discrete space-time

    Energy Technology Data Exchange (ETDEWEB)

    Finster, Felix [NWF I - Mathematik, Universitaet Regensburg, 93040 Regensburg (Germany)

    2007-05-15

    Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

  4. Fermion Systems in Discrete Space-Time

    OpenAIRE

    Finster, Felix

    2006-01-01

    Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

  5. Fermion systems in discrete space-time

    Science.gov (United States)

    Finster, Felix

    2007-05-01

    Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

  6. Time-reversed lasing in the terahertz range and its preliminary study in sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yun, E-mail: shenyunoptics@gmail.com [Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Huaqing [Department of Physics, Nanchang University, Nanchang 330031 (China); Deng, Xiaohua [Institute of Space Science and Technology, Nanchang University, Nanchang 330031 (China); Wang, Guoping [Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

    2017-02-05

    Time-reversed lasing in a uniform slab and a grating structure are investigated in the terahertz range. The results show that both the uniform slab and grating can support terahertz time-reversed lasing. Nevertheless, due to the tunable effective refractive index, the grating structure can not only exhibit time-reversed lasing more effectively and flexibly than a uniform slab, but also can realize significant absorption in a broader operating frequency range. Furthermore, applications of terahertz time-reversed lasing for novel concentration/thickness sensors are preliminarily studied in a single-channel coherent perfect absorber system. - Highlights: • Time-reversed lasing are investigated in the terahertz range. • The grating structure exhibit time-reversed lasing more effectively and flexibly than a uniform slab. • THz time-reversed lasing for novel concentration/thickness sensors are studied.

  7. The timing statistics of spontaneous calcium release in cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Mesfin Asfaw

    Full Text Available A variety of cardiac arrhythmias are initiated by a focal excitation that disrupts the regular beating of the heart. In some cases it is known that these excitations are due to calcium (Ca release from the sarcoplasmic reticulum (SR via propagating subcellular Ca waves. However, it is not understood what are the physiological factors that determine the timing of these excitations at both the subcellular and tissue level. In this paper we apply analytic and numerical approaches to determine the timing statistics of spontaneous Ca release (SCR in a simplified model of a cardiac myocyte. In particular, we compute the mean first passage time (MFPT to SCR, in the case where SCR is initiated by spontaneous Ca sparks, and demonstrate that this quantity exhibits either an algebraic or exponential dependence on system parameters. Based on this analysis we identify the necessary requirements so that SCR occurs on a time scale comparable to the cardiac cycle. Finally, we study how SCR is synchronized across many cells in cardiac tissue, and identify a quantitative measure that determines the relative timing of SCR in an ensemble of cells. Using this approach we identify the physiological conditions so that cell-to-cell variations in the timing of SCR is small compared to the typical duration of an SCR event. We argue further that under these conditions inward currents due to SCR can summate and generate arrhythmogenic triggered excitations in cardiac tissue.

  8. Reversal Negativity and Bistable Stimuli: Attention, Awareness, or Something Else?

    Science.gov (United States)

    Intaite, Monika; Koivisto, Mika; Ruksenas, Osvaldas; Revonsuo, Antti

    2010-01-01

    Ambiguous (or bistable) figures are visual stimuli that have two mutually exclusive perceptual interpretations that spontaneously alternate with each other. Perceptual reversals, as compared with non-reversals, typically elicit a negative difference called reversal negativity (RN), peaking around 250 ms from stimulus onset. The cognitive…

  9. DSP-Based Focusing over Optical Fiber Using Time Reversal

    DEFF Research Database (Denmark)

    Piels, Molly; Porto da Silva, Edson; Estaran Tolosa, Jose Manuel

    2014-01-01

    A time-reversal array in multimode fiber is proposed for lossless switching using passive optical splitters. Numerical investigations are performed, and a two-transmitter array that routes a 3GBd QPSK signal through the physical layer is demonstrated experimentally.......A time-reversal array in multimode fiber is proposed for lossless switching using passive optical splitters. Numerical investigations are performed, and a two-transmitter array that routes a 3GBd QPSK signal through the physical layer is demonstrated experimentally....

  10. Does the association between broken partnership and first time myocardial infarction vary with time after break-up?

    DEFF Research Database (Denmark)

    Kriegbaum, Margit; Christensen, Ulla; Andersen, Per Kragh

    2013-01-01

    Marriage is associated with lower risk of coronary heart disease, but it is unknown if the association depends on time since break-up with a partner. In this study we included both married and unmarried couples to study if the association between broken partnership (BP) and first time incident...

  11. Estimate of Passive Time Reversal Communication Performance in Shallow Water

    Directory of Open Access Journals (Sweden)

    Sunhyo Kim

    2017-12-01

    Full Text Available Time reversal processes have been used to improve communication performance in the severe underwater communication environment characterized by significant multipath channels by reducing inter-symbol interference and increasing signal-to-noise ratio. In general, the performance of the time reversal is strongly related to the behavior of the q -function, which is estimated by a sum of the autocorrelation of the channel impulse response for each channel in the receiver array. The q -function depends on the complexity of the communication channel, the number of channel elements and their spacing. A q -function with a high side-lobe level and a main-lobe width wider than the symbol duration creates a residual ISI (inter-symbol interference, which makes communication difficult even after time reversal is applied. In this paper, we propose a new parameter, E q , to describe the performance of time reversal communication. E q is an estimate of how much of the q -function lies within one symbol duration. The values of E q were estimated using communication data acquired at two different sites: one in which the sound speed ratio of sediment to water was less than unity and one where the ratio was higher than unity. Finally, the parameter E q was compared to the bit error rate and the output signal-to-noise ratio obtained after the time reversal operation. The results show that these parameters are strongly correlated to the parameter E q .

  12. Supersymmetry breaking and composite extra dimensions

    International Nuclear Information System (INIS)

    Luty, Markus A.; Sundrum, Raman

    2002-01-01

    We study supergravity models in four dimensions where the hidden sector is superconformal and strongly coupled over several decades of energy below the Planck scale, before undergoing spontaneous breakdown of scale invariance and supersymmetry. We show that large anomalous dimensions can suppress Kaehler contact terms between the hidden and visible sectors, leading to models in which the hidden sector is 'sequestered' and anomaly-mediated supersymmetry breaking can naturally dominate, thus solving the supersymmetric flavor problem. We construct simple, explicit models of the hidden sector based on supersymmetric QCD in the conformal window. The present approach can be usefully interpreted as having an extra dimension responsible for sequestering replaced by the many states of a (spontaneously broken) strongly coupled superconformal hidden sector, as dictated by the anti-de Sitter conformal field theory correspondence

  13. Naphthalocyanine-based time reversal mirror at 800 nm

    International Nuclear Information System (INIS)

    Galaup, Jean-Pierre; Fraigne, Sebastien; Le Goueet, Jean-Louis; Likforman, Jean-Pierre; Joffre, Manuel

    2004-01-01

    We performed pulse shaping and time reversal experiments using spectral holography based on persistent spectral hole burning in free-base naphthalocyanine-doped films. The application of a new pulse re-compression scheme based on a programmable hole burning material acting as a time reversal mirror is considered. In this work, we adapted the Fourier transform spectral interferometry technique for measuring the amplitude and phase of photon echo signals produced by diffraction of femtosecond pulses on a spectral hologram. We therefore demonstrated that we could control the pulses diffracted from the hologram by shaping and then characterizing these pulses in both amplitude and phase by spectral interferometry

  14. Time-reversed absorbing condition: application to inverse problems

    International Nuclear Information System (INIS)

    Assous, F; Kray, M; Nataf, F; Turkel, E

    2011-01-01

    The aim of this paper is to introduce time-reversed absorbing conditions in time-reversal methods. They enable one to 'recreate the past' without knowing the source which has emitted the signals that are back-propagated. We present two applications in inverse problems: the reduction of the size of the computational domain and the determination, from boundary measurements, of the location and volume of an unknown inclusion. The method does not rely on any a priori knowledge of the physical properties of the inclusion. Numerical tests with the wave and Helmholtz equations illustrate the efficiency of the method. This technique is fairly insensitive to noise in the data

  15. Test of time-reversal invariance at COSY (TRIC)

    Energy Technology Data Exchange (ETDEWEB)

    Eversheim, D., E-mail: evershei@hiskp.uni-bonn.de; Valdau, Yu. [University Bonn, Helmholtz Institut fuer Strahlen- und Kernphysik (Germany); Lorentz, B. [Forschungszentrum Juelich, Institut fuer Kernphysik (Germany)

    2013-03-15

    At the Cooler Synchrotron COSY a novel (P-even, T-odd) null test of time-reversal invariance to an accuracy of 10{sup - 6} is planned as an internal target transmission experiment. The parity conserving time-reversal violating observable is the total cross-section asymmetry A{sub y,xz}. This quantity is measured using a polarized proton beam with an energy of 135 MeV and an internal tensor polarized deuteron target from the PAX atomic beam source. The reaction rate will be measured by means of an integrating beam current transformer. Thus, in this experiment the cooler synchroton ring serves as ideal forward spectrometer, as a detector, and an accelerator.

  16. Chiral vacuum alignment and spontaneous CP violation by four-Fermi operators

    International Nuclear Information System (INIS)

    Rador, Tonguc

    2009-01-01

    In models where there is a global chiral symmetry which spontaneously breaks to its vectorial subgroup, the introduction of an explicit symmetry breaking perturbation will define the true vacuum of the theory. This true vacuum is found via the minimization of the expectation value of the perturbing Hamiltonian between different vacua as prescribed by Dashen. The procedure of finding the correct vacuum of the theory may result in the spontaneous breaking of CP symmetry even if one initially demands CP invariance on the perturbation. In this work we study, in detail, models where the perturbation is provided by four-Fermi operators. We present the exact treatment for models with two fermion flavors and study the three flavor case in depth numerically. We show that after the Dashen procedure is applied the solutions for the true vacuum fall in three classes with different CP breaking patterns. Critical transitions are possible between these classes as one varies the parameters of the perturbation. We rigorously show that at these transitions a pseudo-Goldstone boson mass vanishes. We also advocate, and substantiate with numerical statistical analysis for various types of models, that if one imposes CP invariance on the perturbation before solving the vacuum alignment, the resulting vacuum structure will have a sizable probability for a light pseudo-Goldstone boson mass. That is a statistical variant of Peccei-Quinn mechanism can be speculated to operate.

  17. Fast Times During Spring Breaks: Are Traffic Fatalities Another Consequence?

    OpenAIRE

    French, Michael; Gumus, Gulcin

    2014-01-01

    Every year in the United States, millions of college students travel for spring break, spending billions of dollars. We examine a potential adverse consequence of spring break that has received little attention in the literature - traffic safety. In particular, we estimate the impact of spring break season on fatal passenger vehicle crashes. Using daily county-level longitudinal data on traffic fatalities in popular spring break destinations from 1982-2011, we conduct separate analyses by age...

  18. Time reversal focusing of elastic waves in plates for an educational demonstration.

    Science.gov (United States)

    Heaton, Christopher; Anderson, Brian E; Young, Sarah M

    2017-02-01

    The purpose of this research is to develop a visual demonstration of time reversal focusing of vibrations in a thin plate. Various plate materials are tested to provide optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the vibration coupling efficiency from a shaker to the plate are quantified to illustrate why a given plate provides the best spatially confined focus as well as the highest focal amplitude possible. A single vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing. Table salt is sprinkled onto the plate surface to allow visualization of the high amplitude, spatially localized time reversal focus; the salt is thrown upward only at the focal position. Spatial mapping of the vibration focusing on the plate using the SLDV is correlated to the visual salt jumping demonstration. The time reversal focusing is also used to knock over an object when the object is placed at the focal position; some discussion of optimal objects to use for this demonstration are given.

  19. Computation by symmetry operations in a structured model of the brain: Recognition of rotational invariance and time reversal

    Science.gov (United States)

    McGrann, John V.; Shaw, Gordon L.; Shenoy, Krishna V.; Leng, Xiaodan; Mathews, Robert B.

    1994-06-01

    Symmetries have long been recognized as a vital component of physical and biological systems. What we propose here is that symmetry operations are an important feature of higher brain function and result from the spatial and temporal modularity of the cortex. These symmetry operations arise naturally in the trion model of the cortex. The trion model is a highly structured mathematical realization of the Mountcastle organizational principle [Mountcastle, in The Mindful Brain (MIT, Cambridge, 1978)] in which the cortical column is the basic neural network of the cortex and is comprised of subunit minicolumns, which are idealized as trions with three levels of firing. A columnar network of a small number of trions has a large repertoire of quasistable, periodic spatial-temporal firing magic patterns (MP's), which can be excited. The MP's are related by specific symmetries: Spatial rotation, parity, ``spin'' reversal, and time reversal as well as other ``global'' symmetry operations in this abstract internal language of the brain. These MP's can be readily enhanced (as well as inherent categories of MP's) by only a small change in connection strengths via a Hebb learning rule. Learning introduces small breaking of the symmetries in the connectivities which enables a symmetry in the patterns to be recognized in the Monte Carlo evolution of the MP's. Examples of the recognition of rotational invariance and of a time-reversed pattern are presented. We propose the possibility of building a logic device from the hardware implementation of a higher level architecture of trion cortical columns.

  20. Small break loss of coolant accidents: Bottom and side break

    International Nuclear Information System (INIS)

    Hardy, P.G.; Richter, H.J.

    1987-01-01

    A LOCA can be caused, e.g. by a small break in the primary cooling system. The rate of fluid escaping through such a break will define the time until the core will be uncovered. Therefore the prediction of fluid loss and pressure transient is of major importance to plan for timely action in response to such an event. Stratification of the two phases might be present upstream of the break, thus, the location of the break relative to the vapor-liquid interface and the overall upstream fluid conditions are relevant for the calculation of fluid loss. Experimental results and analyses are presented here for small breaks at the bottom or at the side of a small pressure vessel. It was found that in such a case the onset of the so-called ''vapor pull through'' is important but swelling at sufficient depressurization rates of the liquid due to flashing is also of significance. It was also discovered that in the bottom break the flow rate is strongly dependent on the break entrance quality of the vapour-liquid mixture. The side break can be treated similarly to the bottom break if the interface level is above the break. The analyses developed on the basis of experimental observations showed reasonable agreement of predicted and measured pressure transients. It was possible to calculate the changing interface level and mixture void fraction history in a way compatible with the behavior observed during the experiments. Even though the experiments were performed at low pressures, this work should help to get a better understanding of physical phenomena occurring in a full scale small break LOCA. (orig./HP)

  1. Modelling and Comparative Performance Analysis of a Time-Reversed UWB System

    Directory of Open Access Journals (Sweden)

    Popovski K

    2007-01-01

    Full Text Available The effects of multipath propagation lead to a significant decrease in system performance in most of the proposed ultra-wideband communication systems. A time-reversed system utilises the multipath channel impulse response to decrease receiver complexity, through a prefiltering at the transmitter. This paper discusses the modelling and comparative performance of a UWB system utilising time-reversed communications. System equations are presented, together with a semianalytical formulation on the level of intersymbol interference and multiuser interference. The standardised IEEE 802.15.3a channel model is applied, and the estimated error performance is compared through simulation with the performance of both time-hopped time-reversed and RAKE-based UWB systems.

  2. Hybrid local-order mechanism for inversion symmetry breaking

    Science.gov (United States)

    Wolpert, Emma H.; Overy, Alistair R.; Thygesen, Peter M. M.; Simonov, Arkadiy; Senn, Mark S.; Goodwin, Andrew L.

    2018-04-01

    Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarization from local displacements on the square and cubic lattices. Our model contains two key ingredients: a Kitaev-like orientation-dependent interaction between nearest neighbors and a steric term that acts between next-nearest neighbors. Taken by themselves, each of these two ingredients is incapable of driving long-range symmetry breaking, despite the presence of a broad feature in the corresponding heat-capacity functions. Instead, each component results in a "hidden" transition on cooling to a manifold of degenerate states; the two manifolds are different in the sense that they reflect distinct types of local order. Remarkably, their intersection, i.e., the ground state when both interaction terms are included in the Hamiltonian, supports a spontaneous polarization. In this way, our study demonstrates how local-order mechanisms might be combined to break global inversion symmetry in a manner conceptually similar to that operating in the "hybrid" improper ferroelectrics. We discuss the relevance of our analysis to the emergence of spontaneous polarization in well-studied ferroelectrics such as BaTiO3 and KNbO3.

  3. A digital matched filter for reverse time chaos.

    Science.gov (United States)

    Bailey, J Phillip; Beal, Aubrey N; Dean, Robert N; Hamilton, Michael C

    2016-07-01

    The use of reverse time chaos allows the realization of hardware chaotic systems that can operate at speeds equivalent to existing state of the art while requiring significantly less complex circuitry. Matched filter decoding is possible for the reverse time system since it exhibits a closed form solution formed partially by a linear basis pulse. Coefficients have been calculated and are used to realize the matched filter digitally as a finite impulse response filter. Numerical simulations confirm that this correctly implements a matched filter that can be used for detection of the chaotic signal. In addition, the direct form of the filter has been implemented in hardware description language and demonstrates performance in agreement with numerical results.

  4. Analysis of Time Reversible Born-Oppenheimer Molecular Dynamics

    Directory of Open Access Journals (Sweden)

    Lin Lin

    2013-12-01

    Full Text Available We analyze the time reversible Born-Oppenheimer molecular dynamics (TRBOMD scheme, which preserves the time reversibility of the Born-Oppenheimer molecular dynamics even with non-convergent self-consistent field iteration. In the linear response regime, we derive the stability condition, as well as the accuracy of TRBOMD for computing physical properties, such as the phonon frequency obtained from the molecular dynamics simulation. We connect and compare TRBOMD with Car-Parrinello molecular dynamics in terms of accuracy and stability. We further discuss the accuracy of TRBOMD beyond the linear response regime for non-equilibrium dynamics of nuclei. Our results are demonstrated through numerical experiments using a simplified one-dimensional model for Kohn-Sham density functional theory.

  5. Inflationary implications of supersymmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Borghese, Andrea; Roest, Diederik; Zavala, Ivonne [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2013-07-23

    We discuss a general bound on the possibility to realise inflation in any minimal supergravity with F-terms. The derivation crucially depends on the sGoldstini, the scalar field directions that are singled out by spontaneous supersymmetry breaking. The resulting bound involves both slow-roll parameters and the geometry of the Kähler manifold of the chiral scalars. We analyse the inflationary implications of this bound, and in particular discuss to what extent the requirements of single field and slow-roll can both be met in F-term inflation.

  6. Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry

    International Nuclear Information System (INIS)

    Wang Dianfu; Song Heshan

    2006-01-01

    A maximally generalized Yang-Mills model, which contains, besides the vector part V μ , also an axial-vector part A μ , a scalar part S, a pseudoscalar part P, and a tensor part T μν , is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the maximally generalized Yang-Mills model. The combination of the maximally generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.

  7. Flipped SU(5) times U(1) in superconformal models

    Energy Technology Data Exchange (ETDEWEB)

    Bailin, D.; Katechou, E.K. (Sussex Univ., Brighton (United Kingdom). School of Mathematical and Physical Sciences); Love, A. (London Univ. (United Kingdom))

    1992-01-10

    This paper reports that flipped SU(5) {times} U(1) models are constructed in the framework of tensoring of N = 2 superconformal minimal models quotiented by discrete symmetries. Spontaneous breaking of flipped SU(5) {times} U(1) and extra U(1) factors in the gauge group along F-flat directions of the effective potential is studied.

  8. Time reversal symmetry violation in the YbF molecule

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, B. E., E-mail: ben.sauer@imperial.ac.uk; Devlin, J. A.; Hudson, J. J.; Kara, D. M.; Smallman, I. J.; Tarbutt, M. R.; Hinds, E. A. [Blackett Laboratory Imperial College London, Centre for Cold Matter (United Kingdom)

    2013-03-15

    We present a summary of the techniques used to test time reversal symmetry by measuring the permanent electric dipole moment of the YbF molecule. The results of a recent measurement (Hudson et al., Nature 473:493, 2011) are reported. We review some systematic effects which might mimic time reversal violation and describe how they are overcome. We then discuss improvements to the sensitivity of the apparatus, including both short term technical enhancements as well as a longer term goal to use laser cooled YbF in the experiment.

  9. Goldstone mode and pair-breaking excitations in atomic Fermi superfluids

    Science.gov (United States)

    Hoinka, Sascha; Dyke, Paul; Lingham, Marcus G.; Kinnunen, Jami J.; Bruun, Georg M.; Vale, Chris J.

    2017-10-01

    Spontaneous symmetry breaking is a central paradigm of elementary particle physics, magnetism, superfluidity and superconductivity. According to Goldstone's theorem, phase transitions that break continuous symmetries lead to the existence of gapless excitations in the long-wavelength limit. These Goldstone modes can become the dominant low-energy excitation, showing that symmetry breaking has a profound impact on the physical properties of matter. Here, we present a comprehensive study of the elementary excitations in a homogeneous strongly interacting Fermi gas through the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) of molecules using two-photon Bragg spectroscopy. The spectra exhibit a discrete Goldstone mode, associated with the broken-symmetry superfluid phase, as well as pair-breaking single-particle excitations. Our techniques yield a direct determination of the superfluid pairing gap and speed of sound in close agreement with strong-coupling theories.

  10. Wess-Zumino model as linear σ-model of spontaneously broken conformal and OSp (1,4)-supersymmetries

    International Nuclear Information System (INIS)

    Ivanov, E.A.

    1979-01-01

    The massless Wess-Zumino model is shown to exhibit the spontaneous breaking of global conformal and orthosymplectic supersymmetries on account of the Fubini-type classical solutions to the equations of motion. The group structure of spontaneously broken phase is studied and its particle spectrum is analyzed. The little group of the ground state is found to be the graded subgroup OSp(1,4) of the conformal supergroup. The symmetry with respect to another OSp(1,4) subgroup (OSp(1,4))Ois broken to (2,3)-symmetry with emergence of massive Goldstone fermion. The superfield Weyl transformation is defined and with its help the model action is rewritten in terms of superspace OSp(1,4)/O(1,3), spinorial extension of anti de Sitter space. In such a representation the spontaneously broken phase admits the standard σ-model interpretation. We also construct the OSp(1,4)-analog of the massive Wess-Zumino model and examine its vacuum structure. An effect of the spontaneous breaking of P- and CP-parities with the strength related to anti de Sitter radius is found

  11. Time reversal tests in polarized neutron reactions

    International Nuclear Information System (INIS)

    Asahi, Koichiro; Bowman, J.D.; Crawford, B.

    1998-01-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). In recent years the nuclear weak interaction has been studied in the compound nucleus via parity violation. The observed parity-violating effects are strongly enhanced by nuclear structure. The predictions are that the interaction of polarized neutrons with polarized nuclear targets could be also used to perform sensitive tests of time-reversal-violation because of the nuclear enhancements. The author has designed experiments to search for time-reversal violation in neutron-nucleus interactions. He has also developed techniques to polarize neutrons with laser-polarized 3 He gas targets. Using the polarized 3 He neutron spin filter, he has performed two experiments at LANSCE: an absolute neutron beam polarization measurement with an accuracy of 0.2--0.3% and a neutron spin-rotation measurement on a 139 La sample

  12. Peaking cladding temperature and break equivalent size of intermediate break loss of coolant accident

    International Nuclear Information System (INIS)

    Luo Bangqi

    2012-01-01

    The analysis results of intermediate break loss of coolant accident for the nuclear power plant of million kw level showed to be as following: (1) At the begin of life, the break occur simultaneity reactor shutdown with L(X)P. it's equivalent break size and peaking cladding temperature is respectively 20 cm and 849℃. (2) At the begin of life, the break occur simultaneity reactor shutdown without loop. the reactor coolant pumps will be stop after reactor shutdown 10 minutes, it's equivalent break size and peaking cladding temperature is respectively 10.5 cm and 921℃. (3) At the bur up of 31 GWd/t(EOC1). the break occur simultaneity reactor shutdown without loop, the reactor coolant pumps will be stop after reactor shutdown 20 minutes, it's equivalent break size and peaking cladding temperature is respectively 8 cm and 1145℃. The above analysis results showed that the peaking cladding temperature of intermediate break loss of coolant accident is not only related with the break equivalent size and core bur up, and is closely related with the stop time of coolant pumps because the coolant pumps would drive the coolant from safety system to produce the seal loop in break loop and affect the core coolant flow, results in the fuel cladding temperature increasing or damaging. Therefore, the break spectrum, burn up spectrum, the stop time of coolant pumps and operator action time will need to detail analysis and provide appropriate operating procedure, otherwise the peaking cladding temperature will exceed 1204℃ and threaten the safety of the reactor core when the intermediate break loss of coolant accident occur in some break equivalent size, burn up, stop pumps time and operator action not appropriate. The pressurizer pressure low signal simultaneity containment pressure higher signal were used as the operator manual close the signal of reactor coolant pumps after reactor shutdown of 20 minutes. have successful solved the operator intervention time from 10 minutes

  13. Assessing Spontaneous Combustion Instability with Nonlinear Time Series Analysis

    Science.gov (United States)

    Eberhart, C. J.; Casiano, M. J.

    2015-01-01

    Considerable interest lies in the ability to characterize the onset of spontaneous instabilities within liquid propellant rocket engine (LPRE) combustion devices. Linear techniques, such as fast Fourier transforms, various correlation parameters, and critical damping parameters, have been used at great length for over fifty years. Recently, nonlinear time series methods have been applied to deduce information pertaining to instability incipiency hidden in seemingly stochastic combustion noise. A technique commonly used in biological sciences known as the Multifractal Detrended Fluctuation Analysis has been extended to the combustion dynamics field, and is introduced here as a data analysis approach complementary to linear ones. Advancing, a modified technique is leveraged to extract artifacts of impending combustion instability that present themselves a priori growth to limit cycle amplitudes. Analysis is demonstrated on data from J-2X gas generator testing during which a distinct spontaneous instability was observed. Comparisons are made to previous work wherein the data were characterized using linear approaches. Verification of the technique is performed by examining idealized signals and comparing two separate, independently developed tools.

  14. Hierarchy stability for spontaneously broken theories

    Energy Technology Data Exchange (ETDEWEB)

    Galvan, J B; Perez-Mercader, J; Sanchez, F J

    1987-04-16

    By using Weisberger's method for the integration of heavy degrees of freedom in multiscale theories, we show that tree level hierarchies are not destabilized byquantum corrections in a two-scale, two scalar field theory model where the heavy sector undergoes spontaneous symmetry breaking. We see explicitly the role played by the one-loop heavy log corrections to the effective parameters in maintaining the original tree level hierarchy and in keeping the theory free of hierarchy problems.

  15. Hierarchy stability for spontaneously broken theories

    International Nuclear Information System (INIS)

    Galvan, J.B.; Perez-Mercader, J.; Sanchez, F.J.

    1987-01-01

    By using Weisberger's method for the integration of heavy degrees of freedom in multiscale theories, we show that tree level hierarchies are not destabilized byquantum corrections in a two-scale, two scalar field theory model where the heavy sector undergoes spontaneous symmetry breaking. We see explicitly the role played by the one-loop heavy log corrections to the effective parameters in maintaining the original tree level hierarchy and in keeping the theory free of hierarchy problems. (orig.)

  16. Effective potential and chiral symmetry breaking

    International Nuclear Information System (INIS)

    Hochberg, David

    2010-01-01

    The nonequilibrium effective potential is calculated for the Frank model of spontaneous mirror-symmetry breaking in chemistry in which external noise is introduced to account for random environmental effects. The well-mixed limit, corresponding to negligible diffusion, and the case of diffusion in two space dimensions are studied in detail. White noise has a disordering effect in the former case, whereas in the latter case a phase transition occurs for external noise exceeding a critical intensity which racemizes the system.

  17. Neutron-antineutron oscillation and baryonic majoron: low scale spontaneous baryon violation

    Energy Technology Data Exchange (ETDEWEB)

    Berezhiani, Zurab [Universita dell' Aquila, Dipartimento delle Scienze Fisiche e Chimiche, L' Aquila (Italy); INFN, Laboratori Nazionali Gran Sasso, L' Aquila (Italy)

    2016-12-15

    We discuss the possibility that baryon number B is spontaneously broken at low scales, of the order of MeV or even smaller, inducing the neutron-antineutron oscillation at the experimentally accessible level. An associated Goldstone particle-baryonic majoron can have observable effects in neutron to antineutron transitions in nuclei or dense nuclear matter. By extending baryon number to an anomaly-free B - L symmetry, the baryo-majoron can be identified with the ordinary majoron associated with the spontaneous breaking of lepton number, and it can have interesting implications for neutrinoless 2β decay with the majoron emission. We also discuss the hypothesis that baryon number can be spontaneously broken by QCD itself via the six-quark condensates. (orig.)

  18. Spontaneous Symmetric Breaking Mechanism in the Evolution of Strategic Alliance Based on Markov Switching Model%基于马尔科夫状态转换的战略联盟自发性对称破缺机制

    Institute of Scientific and Technical Information of China (English)

    宋波; 徐飞

    2013-01-01

    This paper focused on the spontaneous symmetry breaking in the evolution of strategic alliance, from systematic perspective, viewed strategic alliance as a complex social economic system, from time, space, material, information and energy five dimensions. And the Markov random model was introduced into the study on the status switching of strategic alliance, and then the spontaneous symmetric breaking mechanism of strategic alliance was illustrated based on the Markov switching model, in order to predict the equilibrium status of strategic alliance. This paper provides a new theory perspective for the research on the stability and evolution of strategic alliance.%针对企业战略联盟演变过程中的自发性对称破缺现象,以系统观的视角,将战略联盟视作一个复杂社会经济系统,从时间、空间、物质、信息和能量5个维度描述战略联盟系统的状态,并将马尔科夫过程的状态随机转换模型引入战略联盟状态迁移的研究,深入阐述联盟自发性对称破缺机制,从而预测联盟的平衡状态,为战略联盟演变及稳定性的研究提供了新的理论视角.

  19. Forecasting long memory time series under a break in persistence

    DEFF Research Database (Denmark)

    Heinen, Florian; Sibbertsen, Philipp; Kruse, Robinson

    We consider the problem of forecasting time series with long memory when the memory parameter is subject to a structural break. By means of a large-scale Monte Carlo study we show that ignoring such a change in persistence leads to substantially reduced forecasting precision. The strength...... of this effect depends on whether the memory parameter is increasing or decreasing over time. A comparison of six forecasting strategies allows us to conclude that pre-testing for a change in persistence is highly recommendable in our setting. In addition we provide an empirical example which underlines...

  20. Low-amplitude instability as a premise for the spontaneous symmetry breaking in the new integrable semidiscrete nonlinear system

    International Nuclear Information System (INIS)

    Vakhnenko, Oleksiy O.; Vakhnenko, Vyacheslav O.

    2014-01-01

    The new integrable semidiscrete multicomponent nonlinear system characterized by two coupling parameters is presented. Relying upon the lowest local conservation laws the concise form of the system is given and its selfconsistent symmetric parametrization in terms of four independent field variables is found. The comprehensive analysis of quartic dispersion equation for the system low-amplitude excitations is made. The criteria distinguishing the domains of stability and instability of low-amplitude excitations are formulated and a collection of qualitatively distinct realizations of a dispersion law are graphically presented. The loop-like structure of a low-amplitude dispersion law of reduced system emerging within certain windows of adjustable coupling parameter turns out to resemble the loop-like structure of a dispersion law typical of beam-plasma oscillations. Basing on the peculiarities of low-amplitude dispersion law as the function of adjustable coupling parameter it is possible to predict the windows of spontaneous symmetry breaking even without an explicit knowledge of the system Lagrangian function. Having been rewritten in terms of properly chosen modified field variables the reduced four wave integrable system can be qualified as consisting of two coupled nonlinear lattice subsystems, namely the self-dual ladder network and the vibrational ones

  1. Interaction matters? : exploring interactive music as a reminder to break sedentary office time

    NARCIS (Netherlands)

    Ren, X.; Lu, Y.; Visser, V.J.J.; Le, P.D.Huy; van den Burg, R.

    2017-01-01

    This paper presents a within-subject field test (n=24) with Flow platform, a smart cushion that uses interactive music to motivate office workers to break excessive sedentary time. In this study, we compared continuous music and interactive music as reminders to inform sedentary time by every

  2. Plane-wave Least-squares Reverse Time Migration

    KAUST Repository

    Dai, Wei

    2012-11-04

    Least-squares reverse time migration is formulated with a new parameterization, where the migration image of each shot is updated separately and a prestack image is produced with common image gathers. The advantage is that it can offer stable convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A regularization term which penalizes the image difference between nearby angles are used to keep the prestack image consistent through all the angles. Numerical tests on a marine dataset is performed to illustrate the advantages of least-squares reverse time migration in the plane-wave domain. Through iterations of least-squares migration, the migration artifacts are reduced and the image resolution is improved. Empirical results suggest that the LSRTM in plane wave domain is an efficient method to improve the image quality and produce common image gathers.

  3. Smoking cessation reverses DNA double-strand breaks in human mononuclear cells.

    Directory of Open Access Journals (Sweden)

    Mari Ishida

    Full Text Available OBJECTIVE: Cigarette smoking is a major risk factor for atherosclerotic cardiovascular disease, which is responsible for a significant proportion of smoking-related deaths. However, the precise mechanism whereby smoking induces this pathology has not been fully delineated. Based on observation of DNA double-strand breaks (DSBs, the most harmful type of DNA damage, in atherosclerotic lesions, we hypothesized that there is a direct association between smoking and DSBs. The goal of this study was to investigate whether smoking induces DSBs and smoking cessation reverses DSBs in vivo through examination of peripheral mononuclear cells (MNCs. APPROACH AND RESULTS: Immunoreactivity of oxidative modification of DNA and DSBs were increased in human atherosclerotic lesions but not in the adjacent normal area. DSBs in human MNCs isolated from the blood of volunteers can be detected as cytologically visible "foci" using an antibody against the phosphorylated form of the histone H2AX (γ-H2AX. Young healthy active smokers (n = 15 showed increased γ-H2AX foci number when compared with non-smokers (n = 12 (foci number/cell: median, 0.37/cell; interquartile range [IQR], 0.31-0.58 vs. 4.36/cell; IQR, 3.09-7.39, p<0.0001. Smoking cessation for 1 month reduced the γ-H2AX foci number (median, 4.44/cell; IQR, 4.36-5.24 to 0.28/cell; IQR, 0.12-0.53, p<0.05. A positive correlation was noted between γ-H2AX foci number and exhaled carbon monoxide levels (r = 0.75, p<0.01. CONCLUSIONS: Smoking induces DSBs in human MNCs in vivo, and importantly, smoking cessation for 1 month resulted in a decrease in DSBs to a level comparable to that seen in non-smokers. These data reinforce the notion that the cigarette smoking induces DSBs and highlight the importance of smoking cessation.

  4. Spontaneous B-L breaking as the origin of the hot early universe

    Energy Technology Data Exchange (ETDEWEB)

    Buchmueller, W.; Domcke, V.; Schmitz, K.

    2012-03-15

    The decay of a false vacuum of unbroken B-L symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase yields hybrid inflation, ending in tachyonic preheating. The dynamics of the B - L breaking Higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy, baryon asymmetry and gravitino dark matter. We study the phase transition for the full supersymmetric Abelian Higgs model. For the subsequent reheating process we give a detailed time-resolved description of all particle abundances. The competition of cosmic expansion and entropy production leads to an intermediate period of constant 'reheating' temperature, during which baryon asymmetry and dark matter are produced. Consistency of hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10 GeV.

  5. Inherited XX sex reversal originating from wild medaka populations.

    Science.gov (United States)

    Shinomiya, A; Otake, H; Hamaguchi, S; Sakaizumi, M

    2010-11-01

    The teleost fish, medaka (Oryzias latipes), has an XX/XY sex-determining mechanism. A Y-linked DM domain gene, DMY, has been isolated by positional cloning as the sex-determining gene in this species. Previously, we conducted a field survey of genotypic sex and found that approximately 1% of wild medaka are sex-reversed (XX males and XY females). Here, we performed genetic analyses of nine spontaneous XX sex-reversed males to elucidate its genetic basis. In all cases, the F(1) progeny were all females, whereas XX males reappeared in the backcross (BC) progeny, suggesting that XX sex reversal is a recessive trait. Although the incidences of sex reversal in the BC progeny were mostly low, 40% were males derived from one XX male. We performed linkage analysis using 55 BC males and located a single major factor, sda-1 (sex-determining autosomal factor-1), controlling sex reversal in an autosomal linkage group. Thus, genes involved in the sex-determining pathway can be isolated from spontaneous mutants in wild populations.

  6. Determination of times maximum insulation in case of internal flooding by pipe break

    International Nuclear Information System (INIS)

    Varas, M. I.; Orteu, E.; Laserna, J. A.

    2014-01-01

    This paper demonstrates the process followed in the preparation of the Manual of floods of Cofrentes NPP to identify the allowed maximum time available to the central in the isolation of a moderate or high energy pipe break, until it affects security (1E) participating in the safe stop of Reactor or in pools of spent fuel cooling-related equipment , and to determine the recommended isolation mode from the point of view of the location of the break or rupture, of the location of the 1E equipment and human factors. (Author)

  7. The initial time-course of headache in patients with spontaneous subarachnoid hemorrhage

    NARCIS (Netherlands)

    Čomić, Hata; Rinkel, Gabriel J.E.; Vergouwen, Mervyn D.I.

    2017-01-01

    Background If acute severe headache disappears early after its onset, the question arises whether subarachnoid hemorrhage (SAH) should still be ruled out. We studied the initial time-course and minimal duration of headache in a consecutive series of neurologically intact patients with spontaneous

  8. The criterion for time symmetry of probabilistic theories and the reversibility of quantum mechanics

    International Nuclear Information System (INIS)

    Holster, A T

    2003-01-01

    Physicists routinely claim that the fundamental laws of physics are 'time symmetric' or 'time reversal invariant' or 'reversible'. In particular, it is claimed that the theory of quantum mechanics is time symmetric. But it is shown in this paper that the orthodox analysis suffers from a fatal conceptual error, because the logical criterion for judging the time symmetry of probabilistic theories has been incorrectly formulated. The correct criterion requires symmetry between future-directed laws and past-directed laws. This criterion is formulated and proved in detail. The orthodox claim that quantum mechanics is reversible is re-evaluated. The property demonstrated in the orthodox analysis is shown to be quite distinct from time reversal invariance. The view of Satosi Watanabe that quantum mechanics is time asymmetric is verified, as well as his view that this feature does not merely show a de facto or 'contingent' asymmetry, as commonly supposed, but implies a genuine failure of time reversal invariance of the laws of quantum mechanics. The laws of quantum mechanics would be incompatible with a time-reversed version of our universe

  9. The relation between invasive and non-invasive tear break-up time ...

    African Journals Online (AJOL)

    Tear stability normal to Nigerians with consideration of gender and age has not been reported. Tear stability in young adults was measured using invasive and non-invasive tear break-up time (TBUT and NIBUT). Forty –five subjects aged 20 to 30 years were selected from among the students of University of. Benin, Edo ...

  10. Tear Film Break-Up Time: Comparison between Patients using Psychiatric Drugs and Healthy Individuals

    Directory of Open Access Journals (Sweden)

    Parvin Dibajnia

    2014-09-01

    Full Text Available Background: Ocular dryness is a well-recognized adverse side effect of many medications. The purpose of this study was to compare tear film stability between psychiatric patients that use lithium carbonate or carbamazepine and normal cases. Materials and Methods: Tear film break up time test was performed in three groups, 30 patients using lithium carbonate, 30 patients using carbamazepine and 30 normal cases. Values of the TBUTs were compared among groups by the independent t-test. Results: Differences between both of patients and control groups were significant (p<0.0001. Conclusion: The results show that these drugs contribute to decrease of tear film break up time.

  11. Some Relations for Quark Confinement and Chiral Symmetry Breaking in QCD

    Directory of Open Access Journals (Sweden)

    Suganuma Hideo

    2017-01-01

    Full Text Available We analytically study the relation between quark confinement and spontaneous chiral-symmetry breaking in QCD. In terms of the Dirac eigenmodes, we derive some formulae for the Polyakov loop, its fluctuations, and the string tension from the Wilson loop. We also investigate the Polyakov loop in terms of the eigenmodes of theWilson, the clover and the domain wall fermion kernels, respectively. For the confinement quantities, the low-lying Dirac/fermion eigenmodes are found to give negligible contribution, while they are essential for chiral symmetry breaking. These relations indicate no direct one-to-one correspondence between confinement and chiral symmetry breaking in QCD, which seems to be natural because confinement is realized independently of the quark mass.

  12. Give me a better break: Choosing workday break activities to maximize resource recovery.

    Science.gov (United States)

    Hunter, Emily M; Wu, Cindy

    2016-02-01

    Surprisingly little research investigates employee breaks at work, and even less research provides prescriptive suggestions for better workday breaks in terms of when, where, and how break activities are most beneficial. Based on the effort-recovery model and using experience sampling methodology, we examined the characteristics of employee workday breaks with 95 employees across 5 workdays. In addition, we examined resources as a mediator between break characteristics and well-being. Multilevel analysis results indicated that activities that were preferred and earlier in the work shift related to more resource recovery following the break. We also found that resources mediated the influence of preferred break activities and time of break on health symptoms and that resource recovery benefited person-level outcomes of emotional exhaustion, job satisfaction, and organizational citizenship behavior. Finally, break length interacted with the number of breaks per day such that longer breaks and frequent short breaks were associated with more resources than infrequent short breaks. (c) 2016 APA, all rights reserved).

  13. study and analysis of asa river hypothetical dam break using hec-ras

    African Journals Online (AJOL)

    Impounded reservoirs provide beneficial functions such as flood control, recreation, hydropower and water supply but they also carry potential risks. Spontaneous dam break phenomenon can occur and the resultant flooding may cause substantial loss of life and property damage downstream of the dam. A hypothetical dam ...

  14. Subtleties in the BABAR measurement of time-reversal violation

    International Nuclear Information System (INIS)

    Efrati, Aielet

    2015-01-01

    A first measurement of time-reversal (T) asymmetries that are not also CP asymmetries has been recently achieved by the B A B AR collaboration. In this talk, which follows the work done in Ref. [1], I discuss the subtleties of this measurement in the presence of direct CP violation, CPT violation, wrong strangeness decays and wrong sign semi-leptonic decays. In particular, I explain why, in order to identify the measured asymmetries with time-reversal violation, one needs to assume (i) the absence of wrong strangeness decays or of CPT violation in strangeness changing decays, and (ii) the absence of wrong sign decays. (paper)

  15. Sum rules for the spontaneous chiral symmetry breaking parameters of QCD

    International Nuclear Information System (INIS)

    Craigie, N.S.; Stern, J.

    1981-03-01

    We discuss in the spirit of the work of Shifman, Vainshtein and Zakharov (SVZ), sum rules involving current-current vacuum correlation functions, whose Wilson expansion starts off with the operators anti qq or (anti qq) 2 , and thus provide information about the chiral symmetry breaking parameters of QCD. We point out that under the type of crude approximations made by SVZ, a value of sub(vac) (250MeV) 3 is obtained from one of these sum rules, in agreement with current expectations. Further we show that a Borel transformed version of the Weinberg sum rule, for VV - AA, current products seem only to make sense for an A 1 mass close to 1.3GeV and it makes little sense with the current algebra mass Msub(A)=anti 2M. We also give an estimate for the chiral symmetry breaking parameters μ 1 6 =2 2 (anti qsub(L) lambda sup(a)γsub(μ)qsub(L))(anti qsub(R) lambdasup(a) γsup(μ)qsub(R)) >sub(vac) entering in the Weinberg sum rules and μ 2 6 =g 2 sub(vac) entering in a new sum rule we propose involving antisymmetric tensor currents J=anti q σsub(μnu) q. (author)

  16. Time reversibility of intracranial human EEG recordings in mesial temporal lobe epilepsy

    Science.gov (United States)

    van der Heyden, M. J.; Diks, C.; Pijn, J. P. M.; Velis, D. N.

    1996-02-01

    Intracranial electroencephalograms from patients suffering from mesial temporal lobe epilepsy were tested for time reversibility. If the recorded time series is irreversible, the input of the recording system cannot be a realisation of a linear Gaussian random process. We confirmed experimentally that the measurement equipment did not introduce irreversibility in the recorded output when the input was a realisation of a linear Gaussian random process. In general, the non-seizure recordings are reversible, whereas the seizure recordings are irreversible. These results suggest that time reversibility is a useful property for the characterisation of human intracranial EEG recordings in mesial temporal lobe epilepsy.

  17. Associations between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10-14-year-old children: The HAPPY study.

    Science.gov (United States)

    Bailey, Daniel P; Charman, Sarah J; Ploetz, Thomas; Savory, Louise A; Kerr, Catherine J

    2017-11-01

    This study examines the association between prolonged sedentary time and breaks in sedentary time with cardiometabolic risk in 10-14-year-old children. This cross-sectional design study analysed accelerometry-determined sedentary behaviour and physical activity collected over 7 days from 111 (66 girls) UK schoolchildren. Objective outcome measures included waist circumference, fasting lipids, fasting glucose, blood pressure, and cardiorespiratory fitness. Logistic regression was used for the main data analysis. After adjustment for confounders, the odds of having hypertriglyceridaemia (P = 0.03) and an increased clustered cardiometabolic risk score (P = 0.05) were significantly higher in children who engaged in more prolonged sedentary bouts per day. The number of breaks in sedentary time per day was not associated with any cardiometabolic risk factor, but longer mean duration of daily breaks in sedentary time were associated with a lower odds of having abdominal adiposity (P = 0.04) and elevated diastolic blood pressure (P = 0.01). These associations may be mediated by engagement in light activity. This study provides evidence that avoiding periods of prolonged uninterrupted sedentary time may be important for reducing cardiometabolic disease risk in children.

  18. Aspects of soft and spontaneous CP violation

    International Nuclear Information System (INIS)

    Frampton, P.H.; Harada, M.

    1999-01-01

    We study four different models for CP violation: the standard Kobayashi-Maskawa (KM) model, the aspon model of spontaneous breaking, and two models of soft breaking. In all except the standard model, the strong CP problem is addressed and solved. Testable predictions for the area of the unitarity triangle and for (ε ' /ε) K are emphasized. The issue of CP violation may well become the first place where the standard model of particle theory is shown definitively to be deficient. There are two reasons for expecting this to happen: (1) the strong CP problem is still not understood in the unadorned standard model and (2) the KM mechanism, although unquestionably present, may not provide the full explanation of ε K and (ε ' /ε) K . copyright 1999 The American Physical Society

  19. Topological sound in active-liquid metamaterials

    Science.gov (United States)

    Souslov, Anton; van Zuiden, Benjamin C.; Bartolo, Denis; Vitelli, Vincenzo

    2017-11-01

    Liquids composed of self-propelled particles have been experimentally realized using molecular, colloidal or macroscopic constituents. These active liquids can flow spontaneously even in the absence of an external drive. Unlike spontaneous active flow, the propagation of density waves in confined active liquids is not well explored. Here, we exploit a mapping between density waves on top of a chiral flow and electrons in a synthetic gauge field to lay out design principles for artificial structures termed topological active metamaterials. We design metamaterials that break time-reversal symmetry using lattices composed of annular channels filled with a spontaneously flowing active liquid. Such active metamaterials support topologically protected sound modes that propagate unidirectionally, without backscattering, along either sample edges or domain walls and despite overdamped particle dynamics. Our work illustrates how parity-symmetry breaking in metamaterial structure combined with microscopic irreversibility of active matter leads to novel functionalities that cannot be achieved using only passive materials.

  20. Plane-wave least-squares reverse-time migration

    KAUST Repository

    Dai, Wei

    2013-06-03

    A plane-wave least-squares reverse-time migration (LSRTM) is formulated with a new parameterization, where the migration image of each shot gather is updated separately and an ensemble of prestack images is produced along with common image gathers. The merits of plane-wave prestack LSRTM are the following: (1) plane-wave prestack LSRTM can sometimes offer stable convergence even when the migration velocity has bulk errors of up to 5%; (2) to significantly reduce computation cost, linear phase-shift encoding is applied to hundreds of shot gathers to produce dozens of plane waves. Unlike phase-shift encoding with random time shifts applied to each shot gather, plane-wave encoding can be effectively applied to data with a marine streamer geometry. (3) Plane-wave prestack LSRTM can provide higher-quality images than standard reverse-time migration. Numerical tests on the Marmousi2 model and a marine field data set are performed to illustrate the benefits of plane-wave LSRTM. Empirical results show that LSRTM in the plane-wave domain, compared to standard reversetime migration, produces images efficiently with fewer artifacts and better spatial resolution. Moreover, the prestack image ensemble accommodates more unknowns to makes it more robust than conventional least-squares migration in the presence of migration velocity errors. © 2013 Society of Exploration Geophysicists.

  1. Time-lapse crystallography snapshots of a double-strand break repair polymerase in action.

    Science.gov (United States)

    Jamsen, Joonas A; Beard, William A; Pedersen, Lars C; Shock, David D; Moon, Andrea F; Krahn, Juno M; Bebenek, Katarzyna; Kunkel, Thomas A; Wilson, Samuel H

    2017-08-15

    DNA polymerase (pol) μ is a DNA-dependent polymerase that incorporates nucleotides during gap-filling synthesis in the non-homologous end-joining pathway of double-strand break repair. Here we report time-lapse X-ray crystallography snapshots of catalytic events during gap-filling DNA synthesis by pol μ. Unique catalytic intermediates and active site conformational changes that underlie catalysis are uncovered, and a transient third (product) metal ion is observed in the product state. The product manganese coordinates phosphate oxygens of the inserted nucleotide and PP i . The product metal is not observed during DNA synthesis in the presence of magnesium. Kinetic analyses indicate that manganese increases the rate constant for deoxynucleoside 5'-triphosphate insertion compared to magnesium. The likely product stabilization role of the manganese product metal in pol μ is discussed. These observations provide insight on structural attributes of this X-family double-strand break repair polymerase that impact its biological function in genome maintenance.DNA polymerase (pol) μ functions in DNA double-strand break repair. Here the authors use time-lapse X-ray crystallography to capture the states of pol µ during the conversion from pre-catalytic to product complex and observe a third transiently bound metal ion in the product state.

  2. Factors affecting timing of closure and non-reversal of temporary ileostomies.

    Science.gov (United States)

    Sier, M F; van Gelder, L; Ubbink, D T; Bemelman, W A; Oostenbroek, R J

    2015-09-01

    Although stoma closure is considered a simple surgical intervention, the interval between construction and reversal is often prolonged, and some ileostomies may never be reversed. We evaluated possible predictors for non-reversal and prolonged interval between construction and reversal. In a cohort study of ileostomy patients treated in a large teaching hospital, we collected data from the surgical complication and enterostomal therapists' registries between January 2001 and December 2011. Parameters responsible for morbidity, mortality, length of stay and time interval between construction and reversal were analysed. Of 485 intentionally temporary ileostomies, 359 were reversed after a median of 5.6 months (IQR 3.8-8.9 months), while 126 (26%) remained permanent. End ileostomy and intra-abdominal abscess independently delayed reversal. Age, end ileostomy, higher body mass index and preoperative radiotherapy were independent factors for non-reversal. Median duration of hospitalisation for reversal was 7.0 days (5-13 days). Morbidity and mortality were 31 and 0.9%, respectively. In 20 patients (5.5%), re-ileostomy was necessary. A substantial number of ileostomies that are intended to be temporary will never be reversed. If reversed, the interval between construction and reversal is longer than anticipated, while morbidity after reversal and duration of hospitalisation are considerable. Besides a temporary ileostomy, there are two other options: no diversion or a permanent colostomy. Shared decision-making is to be preferred in these situations.

  3. Time dependent micromechanics in continuous graphite fiber/epoxy composites with fiber breaks

    Science.gov (United States)

    Zhou, Chao Hui

    Time dependent micromechanics in graphite fiber/epoxy composites around fiber breaks was investigated with micro Raman spectroscopy (MRS) and two shear-lag based composite models, a multi-fiber model (VBI) and a single fiber model (SFM), which aim at predicting the strain/stress evolutions in the composite from the matrix creep behavior and fiber strength statistics. This work is motivated by the need to understand the micromechanics and predict the creep-rupture of the composites. Creep of the unfilled epoxy was characterized under different stress levels and at temperatures up to 80°C, with two power law functions, which provided the modeling parameters used as input for the composite models. Both the VBI and the SFM models showed good agreement with the experimental data obtained with MRS, when inelasticity (interfacial debonding and/or matrix yielding) was not significant. The maximum shear stress near a fiber break relaxed at t-alpha/2 (or as (1+ talpha)-1/2) and the load recovery length increased at talpha/2(or (1+ talpha)1/2) following the model predictions. When the inelastic zone became non-negligible, the viscoelastic VBI model lost its competence, while the SFM with inelasticity showed good agreement with the MRS measurements. Instead of using the real fiber spacing, an effective fiber spacing was used in model predictions, taking into account of the radial decay of the interfacial shear stress from the fiber surface. The comparisons between MRS data and the SFM showed that inelastic zone would initiate when the shear strain at the fiber end exceeds a critical value gammac which was determined to be 5% for this composite system at room temperature and possibly a smaller value at elevated temperatures. The stress concentrations in neighboring intact fibers played important roles in the subsequent fiber failure and damage growth. The VBI model predicts a constant stress concentration factor, 1.33, for the 1st nearest intact fiber, which is in good

  4. Dynamics of Symmetry Breaking and Tachyonic Preheating

    CERN Document Server

    Felder, G; Greene, P B; Kofman, L A; Linde, Andrei D; Tkachev, Igor I; Felder, Gary; Garcia-Bellido, Juan; Greene, Patrick B.; Kofman, Lev; Linde, Andrei; Tkachev, Igor

    2001-01-01

    We reconsider the old problem of the dynamics of spontaneous symmetry breaking using 3d lattice simulations, and develop a theory of tachyonic preheating, which occurs due to the spinodal instability of the scalar field. Tachyonic preheating is so efficient that symmetry breaking typically completes within a single oscillation of the field distribution as it rolls towards the minimum of its effective potential. As an application of this theory we consider preheating in the hybrid inflation scenario, including SUSY-motivated F-term and D-term inflationary models. We show that preheating in hybrid inflation is typically tachyonic and the stage of oscillations of a homogeneous component of the scalar fields driving inflation ends after a single oscillation. Our results may also be relevant for the theory of the formation of disoriented chiral condensates in heavy ion collisions.

  5. The timing of bud break in warming conditions: variation among seven sympatric conifer species from Eastern Canada

    Science.gov (United States)

    Rossi, Sergio; Isabel, Nathalie

    2017-11-01

    Phenological changes are expected with the ongoing global warming, which could create mismatches in the growth patterns among sympatric species or create synchrony with insect herbivores. In this study, we performed a comparative assessment of the timings of bud break among seven conifer species of Eastern Canada by evaluating seedling development in growth chambers under different temperatures (16, 20 and 24 °C). Bud break occurred earliest in Larix laricina, while Pinus strobus and Pinus resinosa had the latest. Warmer conditions advanced bud break, with the greatest effects being observed at the lower temperatures. Mixed models estimated that one additional degree of temperature produced advancements of 5.3 and 2.1 days at 16 and 20 °C, respectively. The hypothesis of an asynchronous change between species under warming was demonstrated only for the last phenological phases (split buds and exposed shoots), and principally in pines. Abies balsamea showed changes in bud break comparable with the other species analysed, rejecting the hypothesis of mismatches under warmer conditions. The observed non-linear responses of the timings of bud break to warming suggest that the major changes in bud phenology should be expected at the lowest temperatures.

  6. Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

    Science.gov (United States)

    Han, Young Keun; Miller, Kevin M

    2009-08-01

    To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

  7. Time Reversal Reconstruction Algorithm Based on PSO Optimized SVM Interpolation for Photoacoustic Imaging

    Directory of Open Access Journals (Sweden)

    Mingjian Sun

    2015-01-01

    Full Text Available Photoacoustic imaging is an innovative imaging technique to image biomedical tissues. The time reversal reconstruction algorithm in which a numerical model of the acoustic forward problem is run backwards in time is widely used. In the paper, a time reversal reconstruction algorithm based on particle swarm optimization (PSO optimized support vector machine (SVM interpolation method is proposed for photoacoustics imaging. Numerical results show that the reconstructed images of the proposed algorithm are more accurate than those of the nearest neighbor interpolation, linear interpolation, and cubic convolution interpolation based time reversal algorithm, which can provide higher imaging quality by using significantly fewer measurement positions or scanning times.

  8. High-resolution and super stacking of time-reversal mirrors in locating seismic sources

    KAUST Repository

    Cao, Weiping; Hanafy, Sherif M.; Schuster, Gerard T.; Zhan, Ge; Boonyasiriwat, Chaiwoot

    2011-01-01

    Time reversal mirrors can be used to backpropagate and refocus incident wavefields to their actual source location, with the subsequent benefits of imaging with high-resolution and super-stacking properties. These benefits of time reversal mirrors

  9. The Efficacy of a Restart Break for Recycling with Optimal Performance Depends Critically on Circadian Timing

    Science.gov (United States)

    Van Dongen, Hans P.A.; Belenky, Gregory; Vila, Bryan J.

    2011-01-01

    Objectives: Under simulated shift-work conditions, we investigated the efficacy of a restart break for maintaining neurobehavioral functioning across consecutive duty cycles, as a function of the circadian timing of the duty periods. Design: As part of a 14-day experiment, subjects underwent two cycles of five simulated daytime or nighttime duty days, separated by a 34-hour restart break. Cognitive functioning and high-fidelity driving simulator performance were tested 4 times per day during the two duty cycles. Lapses on a psychomotor vigilance test (PVT) served as the primary outcome variable. Selected sleep periods were recorded polysomnographically. Setting: The experiment was conducted under standardized, controlled laboratory conditions with continuous monitoring. Participants: Twenty-seven healthy adults (13 men, 14 women; aged 22–39 years) participated in the study. Interventions: Subjects were randomly assigned to a nighttime duty (experimental) condition or a daytime duty (control) condition. The efficacy of the 34-hour restart break for maintaining neurobehavioral functioning from the pre-restart duty cycle to the post-restart duty cycle was compared between these two conditions. Results: Relative to the daytime duty condition, the nighttime duty condition was associated with reduced amounts of sleep, whereas sleep latencies were shortened and slow-wave sleep appeared to be conserved. Neurobehavioral performance measures ranging from lapses of attention on the PVT to calculated fuel consumption on the driving simulators remained optimal across time of day in the daytime duty schedule, but degraded across time of night in the nighttime duty schedule. The 34-hour restart break was efficacious for maintaining PVT performance and other objective neurobehavioral functioning profiles from one duty cycle to the next in the daytime duty condition, but not in the nighttime duty condition. Subjective sleepiness did not reliably track objective neurobehavioral

  10. Spontaneous perseverative turning in rats with radiation-induced hippocampal damage

    International Nuclear Information System (INIS)

    Mickley, G.A.; Ferguson, J.L.; Nemeth, T.J.; Mulvihill, M.A.; Alderks, C.E.

    1989-01-01

    This study found a new behavioral correlate of lesions specific to the dentate granule cell layer of the hippocampus: spontaneous perseverative turning. Irradiation of a portion of the neonatal rat cerebral hemispheres produced hypoplasia of the granule cell layer of the hippocampal dentate gyrus while sparing the rest of the brain. Radiation-induced damage to the hippocampal formation caused rats placed in bowls to spontaneously turn in long, slow bouts without reversals. Irradiated subjects also exhibited other behaviors characteristic of hippocampal damage (e.g., perseveration in spontaneous exploration of the arms of a T-maze, retarded acquisition of a passive avoidance task, and increased horizontal locomotion). These data extend previously reported behavioral correlates of fascia dentata lesions and suggest the usefulness of a bout analysis of spontaneous bowl turning as a measure of nondiscrete-trial spontaneous alternation and a sensitive additional indicator of radiation-induced hippocampal damage

  11. Spontaneous generation and reversals of mean flows in a convectively-generated internal gravity wave field

    Science.gov (United States)

    Couston, Louis-Alexandre; Lecoanet, Daniel; Favier, Benjamin; Le Bars, Michael

    2017-11-01

    We investigate via direct numerical simulations the spontaneous generation and reversals of mean zonal flows in a stably-stratified fluid layer lying above a turbulent convective fluid. Contrary to the leading idealized theories of mean flow generation by self-interacting internal waves, the emergence of a mean flow in a convectively-generated internal gravity wave field is not always possible because nonlinear interactions of waves of different frequencies can disrupt the mean flow generation mechanism. Strong mean flows thus emerge when the divergence of the Reynolds stress resulting from the nonlinear interactions of internal waves produces a strong enough anti-diffusive acceleration for the mean flow, which, as we will demonstrate, is the case when the Prandtl number is sufficiently low, or when the energy input into the internal wavefield by the convection and density stratification are sufficiently large. Implications for mean zonal flow production as observed in the equatorial stratospheres of the Earth, Saturn and Jupiter, and possibly occurring in other geophysical systems such as planetary and stellar interiors will be briefly discussed. Funding provided by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program through Grant Agreement No. 681835-FLUDYCO-ERC-2015-CoG.

  12. Reversing the irreversible: From limit cycles to emergent time symmetry

    Science.gov (United States)

    Cortês, Marina; Smolin, Lee

    2018-01-01

    In 1979 Penrose hypothesized that the arrows of time are explained by the hypothesis that the fundamental laws are time irreversible [R. Penrose, in General Relativity: An Einstein Centenary Survey (1979)]. That is, our reversible laws, such as the standard model and general relativity are effective, and emerge from an underlying fundamental theory which is time irreversible. In [M. Cortês and L. Smolin, Phys. Rev. D 90, 084007 (2014), 10.1103/PhysRevD.90.084007; 90, 044035 (2014), 10.1103/PhysRevD.90.044035; 93, 084039 (2016), 10.1103/PhysRevD.93.084039] we put forward a research program aiming at realizing just this. The aim is to find a fundamental description of physics above the Planck scale, based on irreversible laws, from which will emerge the apparently reversible dynamics we observe on intermediate scales. Here we continue that program and note that a class of discrete dynamical systems are known to exhibit this very property: they have an underlying discrete irreversible evolution, but in the long term exhibit the properties of a time reversible system, in the form of limit cycles. We connect this to our original model proposal in [M. Cortês and L. Smolin, Phys. Rev. D 90, 084007 (2014), 10.1103/PhysRevD.90.084007], and show that the behaviors obtained there can be explained in terms of the same phenomenon: the attraction of the system to a basin of limit cycles, where the dynamics appears to be time reversible. Further than that, we show that our original models exhibit the very same feature: the emergence of quasiparticle excitations obtained in the earlier work in the space-time description is an expression of the system's convergence to limit cycles when seen in the causal set description.

  13. High-resolution and super stacking of time-reversal mirrors in locating seismic sources

    KAUST Repository

    Cao, Weiping

    2011-07-08

    Time reversal mirrors can be used to backpropagate and refocus incident wavefields to their actual source location, with the subsequent benefits of imaging with high-resolution and super-stacking properties. These benefits of time reversal mirrors have been previously verified with computer simulations and laboratory experiments but not with exploration-scale seismic data. We now demonstrate the high-resolution and the super-stacking properties in locating seismic sources with field seismic data that include multiple scattering. Tests on both synthetic data and field data show that a time reversal mirror has the potential to exceed the Rayleigh resolution limit by factors of 4 or more. Results also show that a time reversal mirror has a significant resilience to strong Gaussian noise and that accurate imaging of source locations from passive seismic data can be accomplished with traces having signal-to-noise ratios as low as 0.001. Synthetic tests also demonstrate that time reversal mirrors can sometimes enhance the signal by a factor proportional to the square root of the product of the number of traces, denoted as N and the number of events in the traces. This enhancement property is denoted as super-stacking and greatly exceeds the classical signal-to-noise enhancement factor of. High-resolution and super-stacking are properties also enjoyed by seismic interferometry and reverse-time migration with the exact velocity model. © 2011 European Association of Geoscientists & Engineers.

  14. Competition between the symmetry breaking and onset of collapse in weakly coupled atomic condensates

    International Nuclear Information System (INIS)

    Salasnich, L.; Toigo, F.; Malomed, B. A.

    2010-01-01

    We analyze the symmetry breaking of matter-wave solitons in a pair of cigar-shaped traps coupled by tunneling of atoms. The model is based on a system of linearly coupled nonpolynomial Schroedinger equations. Unlike the well-known spontaneous-symmetry-breaking (SSB) bifurcation in coupled cubic equations, in the present model the SSB competes with the onset of collapse in this system. Stability regions of symmetric and asymmetric solitons, as well as the collapse region, are identified in the system's parameter space.

  15. Partial breaking of N = 1, D = 10 supersymmetry

    International Nuclear Information System (INIS)

    Bellucci, S.

    1999-01-01

    In this paper is described the spontaneous partial breaking of N =1, D =10 supersymmetry to N = (1, 0), d = 6 and its dimensionally-reduced versions in the framework of nonlinear realizations. The basic Goldstone superfield is N = (1, 0), d = 6 hyper multiplet superfield satisfying a nonlinear generalization of the standard hyper multiplet constraint. It is here interpreted the generalized constraint as the manifestly world volume supersymmetric form of equations of motion of the type 1 super 5-brane in D 10. The related issues here addressed are a possible existence of brane extension of off-shell hyper multiplet actions, the possibility to utilize vector N = (1, 0), d =6 supermultiplet as the Goldstone one, and the description of 1/4 breaking of N =1, D = 11 supersymmetry

  16. Least-squares reverse time migration of multiples

    KAUST Repository

    Zhang, Dongliang

    2013-12-06

    The theory of least-squares reverse time migration of multiples (RTMM) is presented. In this method, least squares migration (LSM) is used to image free-surface multiples where the recorded traces are used as the time histories of the virtual sources at the hydrophones and the surface-related multiples are the observed data. For a single source, the entire free-surface becomes an extended virtual source where the downgoing free-surface multiples more fully illuminate the subsurface compared to the primaries. Since each recorded trace is treated as the time history of a virtual source, knowledge of the source wavelet is not required and the ringy time series for each source is automatically deconvolved. If the multiples can be perfectly separated from the primaries, numerical tests on synthetic data for the Sigsbee2B and Marmousi2 models show that least-squares reverse time migration of multiples (LSRTMM) can significantly improve the image quality compared to RTMM or standard reverse time migration (RTM) of primaries. However, if there is imperfect separation and the multiples are strongly interfering with the primaries then LSRTMM images show no significant advantage over the primary migration images. In some cases, they can be of worse quality. Applying LSRTMM to Gulf of Mexico data shows higher signal-to-noise imaging of the salt bottom and top compared to standard RTM images. This is likely attributed to the fact that the target body is just below the sea bed so that the deep water multiples do not have strong interference with the primaries. Migrating a sparsely sampled version of the Marmousi2 ocean bottom seismic data shows that LSM of primaries and LSRTMM provides significantly better imaging than standard RTM. A potential liability of LSRTMM is that multiples require several round trips between the reflector and the free surface, so that high frequencies in the multiples suffer greater attenuation compared to the primary reflections. This can lead to lower

  17. Scanning Emitter Lifetime Imaging Microscopy for Spontaneous Emission Control

    DEFF Research Database (Denmark)

    Frimmer, Martin; Chen, Yuntian; Koenderink, A. Femius

    2011-01-01

    We report an experimental technique to map and exploit the local density of optical states of arbitrary planar nanophotonic structures. The method relies on positioning a spontaneous emitter attached to a scanning probe deterministically and reversibly with respect to its photonic environment while...

  18. Why Older Adults Spend Time Sedentary and Break Their Sedentary Behavior: A Mixed-Methods Approach Using Life-Logging Equipment.

    Science.gov (United States)

    Dontje, Manon L; Leask, Calum F; Harvey, Juliet; Skelton, Dawn A; Chastin, Sebastien F M

    2018-04-01

    Older adults are recommended to reduce their sedentary time to promote healthy ageing. To develop effective interventions identifying when, why, and how older adults are able to change their sitting habits is important. The aim of this mixed-method study was to improve our understanding of reasons for (breaking) sedentary behavior in older adults. Thirty older adults (74.0 [±5.3] years old, 73% women) were asked about their believed reasons for (breaking) sedentary behavior, and about their actual reasons when looking at a personal storyboard with objective records of activPAL monitor data and time-lapse camera pictures showing all their periods of sedentary time in a day. The most often mentioned believed reason for remaining sedentary was television/radio (mentioned by 48.3%), while eating/drinking was most often mentioned as actual reason (96.6%). Only 17.2% believed that food/tea preparation was a reason to break up sitting, while this was an actual reason for 82.8% of the study sample. Results of this study show that there is a discrepancy between believed and actual reasons for (breaking) sedentary behavior. These findings suggest developing interventions utilizing the actual reasons for breaking sedentary behavior to reduce sedentary time in older adults.

  19. The imaginary-time path integral and non-time-reversal-invariant saddle points of the Euclidean action

    International Nuclear Information System (INIS)

    Dasgupta, I.

    1998-01-01

    We discuss new bounce-like (but non-time-reversal-invariant) solutions to Euclidean equations of motion, which we dub boomerons. In the Euclidean path integral approach to quantum theories, boomerons make an imaginary contribution to the vacuum energy. The fake vacuum instability can be removed by cancelling boomeron contributions against contributions from time reversed boomerons (anti-boomerons). The cancellation rests on a sign choice whose significance is not completely understood in the path integral method. (orig.)

  20. Colour-symmetry-breaking effects in hard processes

    International Nuclear Information System (INIS)

    Efremov, A.V.

    1982-01-01

    A possibility of colour symmetry U(1)xSU(3)sub(C) spontaneous breaking and integer-charged quarks is considered. It is argued that one-photon processes are sensitive only to the colour-averaged charges of quarks and gluons. The true charges can be observed in rigid processes involving at least two real photons. The available now experimental data on processes #betta#p → #betta#X, #betta##betta# → jet+jet are in better agreement with the integer-charges than with the standard QCD

  1. The Organization of Behavior Over Time: Insights from Mid-Session Reversal

    OpenAIRE

    Rayburn-Reeves, Rebecca M.; Cook, Robert G.

    2016-01-01

    What are the mechanisms by which behavior is organized sequentially over time? The recently developed mid-session reversal (MSR) task offers new insights into this fundamental question. The typical MSR task is arranged to have a single reversed discrimination occurring in a consistent location within each session and across sessions. In this task, we examine the relevance of time, reinforcement, and other factors as the switching cue in the sequential modulation of control in MSR. New analyse...

  2. Fuel bundle impact velocities due to reverse flow

    International Nuclear Information System (INIS)

    Wahba, N.N.; Locke, K.E.

    1996-01-01

    If a break should occur in the inlet feeder or inlet header of a CANDU reactor, the rapid depressurization will cause the channel flow(s) to reverse. Depending on the gap between the upstream bundle and shield plug, the string of bundles will accelerate in the reverse direction and impact with the upstream shield plug. The reverse flow impact velocities have been calculated for various operating states for the Bruce NGS A reactors. The sensitivity to several analysis assumptions has been determined. (author)

  3. Multi-source least-squares reverse time migration

    KAUST Repository

    Dai, Wei

    2012-06-15

    Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

  4. Multi-source least-squares reverse time migration

    KAUST Repository

    Dai, Wei; Fowler, Paul J.; Schuster, Gerard T.

    2012-01-01

    Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

  5. Sgoldstino-less inflation and low energy SUSY breaking

    Energy Technology Data Exchange (ETDEWEB)

    Argurio, Riccardo [Physique Théorique et Mathématique and International Solvay Institutes, Université Libre de Bruxelles, CP231, B-1050 Brussels (Belgium); Coone, Dries; Mariotti, Alberto [Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium); Heurtier, Lucien, E-mail: rargurio@ulb.ac.be, E-mail: a.a.coone@rug.nl, E-mail: lucien.heurtier@ulb.ac.be, E-mail: alberto.mariotti@vub.ac.be [Service de Physique Théorique, Université Libre de Bruxelles, CP225, B-1050 Brussels (Belgium)

    2017-07-01

    We assess the range of validity of sgoldstino-less inflation in a scenario of low energy supersymmetry breaking. We first analyze the consistency conditions that an effective theory of the inflaton and goldstino superfields should satisfy in order to be faithfully described by a sgoldstino-less model. Enlarging the scope of previous studies, we investigate the case where the effective field theory cut-off, and hence also the sgoldstino mass, are inflaton-dependent. We then introduce a UV complete model where one can realize successfully sgoldstino-less inflation and gauge mediation of supersymmetry breaking, combining the α-attractor mechanism and a weakly coupled model of spontaneous breaking of supersymmetry. In this class of models we find that, given current limits on superpartner masses, the gravitino mass has a lower bound of the order of the MeV, i.e. we cannot reach very low supersymmetry breaking scales. On the plus side, we recognize that in this framework, one can derive the complete superpartner spectrum as well as compute inflation observables, the reheating temperature, and address the gravitino overabundance problem. We then show that further constraints come from collider results and inflation observables. Their non trivial interplay seems a staple feature of phenomenological studies of supersymmetric inflationary models.

  6. Non-linear time reversal ultrasonic pseudo-tomography

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Vejvodová, Šárka; Krofta, Josef; Převorovský, David

    2011-01-01

    Roč. 6, 3/4 (2011), s. 206-213 ISSN 1741-8410. [NDT in Progress. Praha, 05.11.2007-07.11.2007] R&D Projects: GA MPO(CZ) FR-TI1/274 Institutional research plan: CEZ:AV0Z20760514 Keywords : NDT * nonlinear elastic wave spectroscopy * time reversal mirrors * ultrasonic pseudo-tomography Subject RIV: BI - Acoustics http://www.inderscience.com/offer.php?id=43216

  7. Effective field theory of emergent symmetry breaking in deformed atomic nuclei

    International Nuclear Information System (INIS)

    Papenbrock, T; Weidenmüller, H A

    2015-01-01

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. We extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. In deformed nuclei these are vibrational modes each of which serves as band head of a rotational band. (paper)

  8. Application of reverse transcription-PCR and real-time PCR in nanotoxicity research.

    Science.gov (United States)

    Mo, Yiqun; Wan, Rong; Zhang, Qunwei

    2012-01-01

    Reverse transcription-polymerase chain reaction (RT-PCR) is a relatively simple and inexpensive technique to determine the expression level of target genes and is widely used in biomedical science research including nanotoxicology studies for semiquantitative analysis. Real-time PCR allows for the detection of PCR amplification in the exponential growth phase of the reaction and is much more quantitative than traditional RT-PCR. Although a number of kits and reagents for RT-PCR and real-time PCR are commercially available, the basic principles are the same. Here, we describe the procedures for total RNA isolation by using TRI Reagent, for reverse transcription (RT) by M-MLV reverse transcriptase, and for PCR by GoTaq(®) DNA Polymerase. And real-time PCR will be performed on an iQ5 multicolor real-time PCR detection system by using iQ™ SYBR Green Supermix.

  9. Investigation of the effects of metal-wire resonators in sub-wavelength array based on time-reversal technique

    International Nuclear Information System (INIS)

    Tu, Hui-Lin; Xiao, Shao-Qiu

    2016-01-01

    The resonant metalens consisting of metal-wire resonators with equally finite length can break the diffraction barrier well suited for super-resolution imaging. In this study, a basic combination constructed by two metal-wire resonators with different lengths is proposed, and its resonant characteristics is analyzed using the method of moments (MoM). Based on the time reversal (TR) technique, this kind of combination can be applied to a sub-wavelength two-element antenna array with a 1/40-wavelength interval to make the elements work simultaneously with little interference in the frequency band of 1.0-1.5 GHz and 1.5-2.0 GHz, respectively. The simulations and experiments show that analysis of MoM and the application of the resonators can be used to design multi-frequency sub-wavelength antenna arrays efficiently. This general design method is convenient and can be used for many applications, such as weakening jamming effectiveness in communication systems, and sub-wavelength imaging in a broad frequency band.

  10. Observation of magnetic flux generated spontaneously during a rapid quench of superconducting films

    International Nuclear Information System (INIS)

    Maniv, A.; Polturak, E.; Koren, G.

    2003-01-01

    We report observations of spontaneous formation of magnetic flux lines during a rapid quench of YBa 2 Cu 3 O 7-δ films through T c . This effect is predicted according to the Kibble-Zurek mechanism of creation of topological defects of the order parameter during a symmetry-breaking phase transition. Our previous experiment, at a quench rate of 20 K/s, gave null results. In the present experiment, the quench rate was increased to >10 8 K/s. The amount of spontaneous flux increases weakly with the cooling rate

  11. String dynamics, spontaneous breaking of supersymmetry, and dual scalar field theory

    International Nuclear Information System (INIS)

    Liu Luxin

    2009-01-01

    The dynamics of a vortex string, which describes the Nambu-Goldstone modes of the spontaneous breakdown of the target space D=4, N=1 supersymmetry and internal U(1) R symmetry to the world sheet ISO(1,1) symmetry, is constructed by using the approach of nonlinear realization. The resulting action describing the low energy oscillations of the string into the covolume (super)space is found to have an invariant synthesis form of the Akulov-Volkov and Nambu-Goto actions. Its dual scalar field action is obtained by means of introducing two vectorial Lagrangian multipliers into the action of the string.

  12. Energy expenditure and heart rate response to breaking up sedentary time with three different physical activity interventions.

    Science.gov (United States)

    Carter, S E; Jones, M; Gladwell, V F

    2015-05-01

    Prolonged sedentary behaviour is associated with increased cardiovascular disease risk and decreased energy expenditure (EE). Workplace interventions breaking up sedentary time have increased EE but the cardiovascular responses are unknown. The practicalities of these interventions, such as required costs and workplace adaptations, are questioned. Calisthenics exercises overcome such limitations, but have not been assessed. The aim of this study was to assess the EE and heart rate (HR) response when breaking up sedentary time with a short bout of standing, walking or calisthenics. Twenty healthy participants (15 male) completed four 30 min conditions: a) 30 min sitting, or breaking up this period with two minutes of b) standing, c) treadmill walking (4 km·h(-1)) or d) a set of calisthenics exercises (including squats and lunges). HR and EE (indirect calorimetry) were assessed throughout. During the activity break, calisthenics caused the highest HR (90 ± 12 bpm) compared to all other conditions (Sit: 70 ± 12 bpm; Stand:72 ± 13 bpm; Walk:84 ± 10 bpm; p workplace sedentary time and improve cardiovascular health and assist in weight management. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. e +e- modes and U(1) spontaneous chiral symmetry breaking

    International Nuclear Information System (INIS)

    Steininger, K.

    1992-01-01

    In this paper, motivated by evidence for a chiral phase transition in strong coupling lattice QED, the authors calculate the two-particle spectrum of the broken QED phase. This is done in the framework of a Nambu and Jona-Lasinio model with U(1) symmetry including chiral symmetry and symmetry breaking properties of QED. The second order chiral phase transition behavior in our model and in lattice QED are in excellent agreement. The authors then present a detailed analysis of the spectra of the e + e - modes in the broken phase. The authors examine whether these modes have any possible relationship to the narrow e + e - resonances found in soft heavy ion collisions at GSL. The authors' answer is negative

  14. Spontaneous breaking of Lorentz symmetry by ghost condensation in perturbative quantum gravity

    Science.gov (United States)

    Faizal, Mir

    2011-10-01

    In this paper, we will study the spontaneous breakdown of the Lorentz symmetry by ghost condensation in perturbative quantum gravity. Our analysis will be done in the Curci-Ferrari gauge. We will also analyse the modification of the BRST and anti-BRST transformations by the formation of this ghost condensate. It will be shown that even though the modified BRST and anti-BRST transformations are not nilpotent, their nilpotency is restored on-shell.

  15. Spontaneously broken realization of supersymmetry in supergravity

    International Nuclear Information System (INIS)

    Ferrara, S.; Trieste Univ.

    1979-01-01

    It is shown that if supersymmetry is relevant for the physical world it must be broken either spontaneously or explicitly. Renormalizability and simplicity are in favor of a spontaneous realization of the symmetry breaking. When supersymmetry is spontaneously broken the spinorial analogue of the Goldstone phenomenon occurs, namely massless particles arise in the spectrum of the theory which carry the same quantum numbers of the broken generators Qsup(i) they are N spin 1/2 Goldstone fermions (goldstinos). These particles may be eaten by spin 3/2 gauge particles (gravitinos) when supersymmetry is gauged. It is shown that both the Higgs effect and super Higgs effect have taken place. 8 of the spin 1/2 particles have been eaten by the spin 3/2 particles and 24 of 70 scalars have been eaten by the spin 3/2 particles and 24 of 70 scalars have been eaten by 24 of the 28 vector particles to provide them with mass. The conclusion is that the number of mass relations is, in general, equal to r-1, where r is the rank of the algebra which generates the spectrum

  16. Time-reversal invariance in multiple collisions between coupled masses

    International Nuclear Information System (INIS)

    Crawford, F.S.

    1989-01-01

    The time evolution of two mechanical oscillators coupled by a spring can (but need not) exhibit an instant t = 2t' when the initial conditions at t = 0 have been exactly restored. When that is the case, then at t = t' energy and momentum have been exchanged exactly as in an elastic collision between two free particles, and the evolution of the system from t = t' to 2t' is related to that from 0 to t' by time-reversal invariance. A similar ''simulation of elastic scattering'' at t = t' can occur for two free particles coupled via collisions with an intermediary mass that bounces back and forth between the two particles provided the intermediary is left at rest at t = t'. Examined here is the time evolution of the exchange of momentum and energy for these two examples, determining the values of the coupling spring constant (or mass value) of the intermediating spring (or mass) needed to simulate single elastic scattering between free particles, and looking at the manifestation of time-reversal invariance

  17. Simulation of breaking waves using the high-order spectral method with laboratory experiments: Wave-breaking onset

    Science.gov (United States)

    Seiffert, Betsy R.; Ducrozet, Guillaume; Bonnefoy, Félicien

    2017-11-01

    This study investigates a wave-breaking onset criteria to be implemented in the non-linear potential flow solver HOS-NWT. The model is a computationally efficient, open source code, which solves for the free surface in a numerical wave tank using the High-Order Spectral (HOS) method. The goal of this study is to determine the best method to identify the onset of random single and multiple breaking waves over a large domain at the exact time they occur. To identify breaking waves, a breaking onset criteria based on the ratio of local energy flux velocity to the local crest velocity, introduced by Barthelemy et al. (2017) is selected. The breaking parameter is uniquely applied in the numerical model in that calculations of the breaking onset criteria ratio are not made only at the location of the wave crest, but at every point in the domain and at every time step. This allows the model to calculate the onset of a breaking wave the moment it happens, and without knowing anything about the wave a priori. The application of the breaking criteria at every point in the domain and at every time step requires the phase velocity to be calculated instantaneously everywhere in the domain and at every time step. This is achieved by calculating the instantaneous phase velocity using the Hilbert transform and dispersion relation. A comparison between more traditional crest-tracking techniques shows the calculation of phase velocity using Hilbert transform at the location of the breaking wave crest provides a good approximation of crest velocity. The ability of the selected wave breaking criteria to predict single and multiple breaking events in two dimensions is validated by a series of large-scale experiments. Breaking waves are generated by energy focusing and modulational instability methods, with a wide range of primary frequencies. Steep irregular waves which lead to breaking waves, and irregular waves with an energy focusing wave superimposed are also generated. This set of

  18. Quantum-Enhanced Sensing Based on Time Reversal of Nonlinear Dynamics.

    Science.gov (United States)

    Linnemann, D; Strobel, H; Muessel, W; Schulz, J; Lewis-Swan, R J; Kheruntsyan, K V; Oberthaler, M K

    2016-07-01

    We experimentally demonstrate a nonlinear detection scheme exploiting time-reversal dynamics that disentangles continuous variable entangled states for feasible readout. Spin-exchange dynamics of Bose-Einstein condensates is used as the nonlinear mechanism which not only generates entangled states but can also be time reversed by controlled phase imprinting. For demonstration of a quantum-enhanced measurement we construct an active atom SU(1,1) interferometer, where entangled state preparation and nonlinear readout both consist of parametric amplification. This scheme is capable of exhausting the quantum resource by detecting solely mean atom numbers. Controlled nonlinear transformations widen the spectrum of useful entangled states for applied quantum technologies.

  19. Time-Reversal MUSIC Imaging with Time-Domain Gating Technique

    Science.gov (United States)

    Choi, Heedong; Ogawa, Yasutaka; Nishimura, Toshihiko; Ohgane, Takeo

    A time-reversal (TR) approach with multiple signal classification (MUSIC) provides super-resolution for detection and localization using multistatic data collected from an array antenna system. The theory of TR-MUSIC assumes that the number of antenna elements is greater than that of scatterers (targets). Furthermore, it requires many sets of frequency-domain data (snapshots) in seriously noisy environments. Unfortunately, these conditions are not practical for real environments due to the restriction of a reasonable antenna structure as well as limited measurement time. We propose an approach that treats both noise reduction and relaxation of the transceiver restriction by using a time-domain gating technique accompanied with the Fourier transform before applying the TR-MUSIC imaging algorithm. Instead of utilizing the conventional multistatic data matrix (MDM), we employ a modified MDM obtained from the gating technique. The resulting imaging functions yield more reliable images with only a few snapshots regardless of the limitation of the antenna arrays.

  20. Focusing over Optical Fiber Using Time Reversal

    DEFF Research Database (Denmark)

    Piels, Molly; Porto da Silva, Edson; Estaran Tolosa, Jose Manuel

    2015-01-01

    A time-reversal array in multimode fiber is proposed for lossless remotely controlled switching using passive optical splitters. The signal to be transmitted is digitally pre-distorted so that it is routed through the physical layer in order to arrive at only one receiver in an array. System...... performance in the presence of additive white gaussian noise, modal group delay, and timing error is investigated numerically for single-mode and 10-mode fiber. Focusing using a two-transmitter array and 44 km of single- mode fiber is demonstrated experimentally for 3 GBd QPSK signals with a bit error rate...

  1. Anti-Aliasing filter for reverse-time migration

    KAUST Repository

    Zhan, Ge

    2012-01-01

    We develop an anti-aliasing filter for reverse-time migration (RTM). It is similar to the traditional anti-aliasing filter used for Kirchhoff migration in that it low-pass filters the migration operator so that the dominant wavelength in the operator is greater than two times the trace sampling interval, except it is applied to both primary and multiple reflection events. Instead of applying this filter to the data in the traditional RTM operation, we apply the anti-aliasing filter to the generalized diffraction-stack migration operator. This gives the same migration image as computed by anti-aliased RTM. Download

  2. The effects of Vitamin A on tear break-up time of young adults ...

    African Journals Online (AJOL)

    The effects of Vitamin A on tear break-up time of young adults. ... healthy young adults; 50 males and 50 females all within the ages of 18 and 30 years were used for this study. Results showed a range of 13-28 seconds and a mean TBUT of

  3. Direct-Current Forced Interruption and Breaking Performance of Spiral-Type Contacts in Aero Applications

    Directory of Open Access Journals (Sweden)

    Wenlei Huo

    2017-05-01

    Full Text Available This paper analyses the transient characteristics and breaking performance of direct-current (DC forced-interruption vacuum interrupters in 270 V power-supply systems. Three stages are identified in forced interruption: the DC-arcing stage, current-commutation stage, and voltage-recovery stage. During the current-commutation stage, the reverse peak-current coefficient k, which is a key design factor, is used to calculate the rate of current at zero-crossing (di/dt. MATLAB/Simulink simulation models are established to obtain the transient characteristics influenced by the forced-commutation branch parameters and the coefficient k. To study the breaking performance of spiral-type contacts, experiments are conducted for different contact materials and arcing times for currents less than 3.5 kA. During the DC-arcing stage, a locally intensive burning arc is observed in the CuW80 contact; however, it is not observed in the CuCr50 contact. On examining the re-ignition interruption results of the CuW80 contact, the intensive burning arc is found to be positioned within a possible re-ignition region. When the arcing time is longer than 1 ms, the intensive burning arc occurs and affects the breaking performance of the spiral-type contacts. If the DC-arcing stage is prolonged, the total arcing energy increases, which leads to a lower breaking capacity.

  4. Cooperative spontaneous emission of nano-emitters with inter-emitter coupling in a leaky microcavity

    International Nuclear Information System (INIS)

    Hong, Suc-Kyoung; Nam, Seog Woo; Yang, Hyung Jin

    2015-01-01

    We study the spontaneous emission from a few two-level nano-emitters placed in a leaky microcavity with Lorentzian spectral density near a critically damped regime. Collective features of the spontaneous emission are investigated by numerical analysis of the excitation dynamics when initially one nano-emitter is totally excited but we do not know which one. The results show that there are three decay rates in the excitation dynamics, two for simple exponential decays and one for damped oscillatory decay. The excitation dynamics is found to critically depend on the regime of the system. It is shown that the spontaneous emission is enhanced or suppressed depending on whether the system is in the underdamped or overdamped regime, respectively. On the other hand, the cooperative spontaneous emission is suppressed in the underdamped while it is enhanced in the overdamped regime. Furthermore, the effect of the direct inter-emitter coupling on the breaking of the cooperativeness of the spontaneous emission is shown as well. (paper)

  5. Spontaneous recovery of superhydrophobicity on nanotextured surfaces

    Science.gov (United States)

    Prakash, Suruchi; Xi, Erte; Patel, Amish J.

    2016-01-01

    Rough or textured hydrophobic surfaces are dubbed “superhydrophobic” due to their numerous desirable properties, such as water repellency and interfacial slip. Superhydrophobicity stems from an aversion of water for the hydrophobic surface texture, so that a water droplet in the superhydrophobic “Cassie state” contacts only the tips of the rough surface. However, superhydrophobicity is remarkably fragile and can break down due to the wetting of the surface texture to yield the “Wenzel state” under various conditions, such as elevated pressures or droplet impact. Moreover, due to large energetic barriers that impede the reverse transition (dewetting), this breakdown in superhydrophobicity is widely believed to be irreversible. Using molecular simulations in conjunction with enhanced sampling techniques, here we show that on surfaces with nanoscale texture, water density fluctuations can lead to a reduction in the free energetic barriers to dewetting by circumventing the classical dewetting pathways. In particular, the fluctuation-mediated dewetting pathway involves a number of transitions between distinct dewetted morphologies, with each transition lowering the resistance to dewetting. Importantly, an understanding of the mechanistic pathways to dewetting and their dependence on pressure allows us to augment the surface texture design, so that the barriers to dewetting are eliminated altogether and the Wenzel state becomes unstable at ambient conditions. Such robust surfaces, which defy classical expectations and can spontaneously recover their superhydrophobicity, could have widespread importance, from underwater operation to phase-change heat transfer applications. PMID:27140619

  6. Fermion masses in potential models of chiral symmetry breaking

    International Nuclear Information System (INIS)

    Jaroszewicz, T.

    1983-01-01

    A class of models of spontaneous chiral symmetry breaking is considered, based on the Hamiltonian with an instantaneous potential interaction of fermions. An explicit mass term mΨ-barΨ is included and the physical meaning of the mass parameter is discussed. It is shown that if the Hamiltonian is normal-ordered (i.e. self-energy omitted), then the mass m introduced in the Hamiltonian is not the current mass appearing in the current algebra relations. (author)

  7. Comparison of source moment tensor recovered by diffraction stacking migration and source time reversal imaging

    Science.gov (United States)

    Zhang, Q.; Zhang, W.

    2017-12-01

    Diffraction stacking migration is an automatic location methods and widely used in microseismic monitoring of the hydraulic fracturing. It utilizes the stacking of thousands waveform to enhance signal-to-noise ratio of weak events. For surface monitoring, the diffraction stacking method is suffered from polarity reverse among receivers due to radiation pattern of moment source. Joint determination of location and source mechanism has been proposed to overcome the polarity problem but needs significantly increased computational calculations. As an effective method to recover source moment tensor, time reversal imaging based on wave equation can locate microseismic event by using interferometry on the image to extract source position. However, the time reversal imaging is very time consuming compared to the diffraction stacking location because of wave-equation simulation.In this study, we compare the image from diffraction stacking and time reversal imaging to check if the diffraction stacking can obtain similar moment tensor as time reversal imaging. We found that image produced by taking the largest imaging value at each point along time axis does not exhibit the radiation pattern, while with the same level of calculation efficiency, the image produced for each trial origin time can generate radiation pattern similar to time reversal imaging procedure. Thus it is potential to locate the source position by the diffraction stacking method for general moment tensor sources.

  8. Anatomy of new SUSY breaking holographic RG flows

    Energy Technology Data Exchange (ETDEWEB)

    Argurio, Riccardo [Physique Théorique et Mathématique andInternational Solvay Institutes, Université Libre de Bruxelles,C.P. 231, 1050 Brussels (Belgium); Musso, Daniele [International Center of Theoretical Physics (ICTP),Strada Costiera 11, I 34014 Trieste (Italy); Redigolo, Diego [Physique Théorique et Mathématique andInternational Solvay Institutes, Université Libre de Bruxelles,C.P. 231, 1050 Brussels (Belgium); Sorbonne Universités, UPMC University Paris 06, UMR 7589, LPTHE,F-75005, Paris (France); CNRS, UMR 7589, LPTHE,F-75005, Paris (France)

    2015-03-17

    We find and thoroughly study new supergravity domain wall solutions which are holographic realizations of supersymmetry breaking strongly coupled gauge theories. We set ourselves in an N=2 gauged supergravity with a minimal content in order to reproduce a dual N=1 effective SCFT which has a U(1){sub R} symmetry, a chiral operator whose components are responsible for triggering the RG flow, and an additional U(1){sub F} symmetry. We present a full three dimensional parameter space of solutions, which generically break supersymmetry. Some known solutions are recovered for specific sets of values of the parameters, with the new solutions interpolating between them. The generic backgrounds being singular, we provide a stability test of their dual theories by showing that there are no tachyonic resonances in the two point correlators. We compute the latter by holographic renormalization. We also carefully analyze the appearance of massless modes, such as the dilaton and the R axion, when the respective symmetries are spontaneously broken, and their lifting when the breaking is explicit. We further comment on the application of such class of backgrounds as archetypes of strongly coupled hidden sectors for gauge mediation of supersymmetry breaking. In particular, we show that it is possible to model in this way all types of hierarchies between the visible sector gaugino and sfermion masses.

  9. p53 regulates the repair of DNA double-strand breaks by both homologous and non-homologous recombination

    International Nuclear Information System (INIS)

    Willers, H.; Powell, S.N.; Dahm-Daphi, J.

    2003-01-01

    Full text: p53 is known to suppress spontaneous homologous recombination (HR), while its role in non-homologous recombination (NHR) remains to be clarified. Here, we sought to determine the influence of p53 on the repair of chromosomal double-strand breaks (DSBs) by HR or NHR using specially designed recombination substrates that integrate into the genome. Isogenic mouse fibroblast pairs with or without expression of exogenous p53 protein were utilized. A reporter plasmid carrying a mutated XGPRT gene was chromosomally integrated and DSBs were generated within the plasmid by the I-SceI endonuclease. Subsequent homology-mediated repair from an episomal donor resulted in XGPRT reconstitution and cellular resistance to a selection antibiotic. Analogously, the repair of chromosomal I-SceI breaks by NHR using another novel reporter plasmid restored XGPRT translation. For p53-null cells, the mean frequency of I-SceI break repair via HR was 5.5 x 10 -4 . The p53-Val135 mutant, which previously has been shown to suppress spontaneous HR by 14-fold employing the same cell system and reporter gene, only caused a 2- to 3-fold suppression of break-induced HR. In contrast, a dramatic effect of p53 on repair via NHR was found. Preliminary sequence analysis indicated that there was at least a 1000-fold reduction of illegitimate repair events resulting in loss of sequence at the break sites. The observed effects were mediated by p53 mutants defective in regulation of the cell-cycle and apoptosis. The main findings were: (1) p53 virtually blocked illegitimate rejoining of chromosomal ends. (2) The suppression of homologous DSB repair was less pronounced than the inhibition of spontaneous HR. We hypothesize that p53 allows to a certain extent error-free homology-dependent repair to proceed, while blocking error-prone NHR. The data support and extent a previous model, in which p53 maintains genomic stability by regulating recombination independently of its transactivation function

  10. Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth

    Science.gov (United States)

    Konstantinov, Konstantin K.; Konstantinova, Alisa F.

    2018-03-01

    Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered. It was shown that depending on the model and the values of the parameters, chiral symmetry breaking may occur in up to about 10% out of all possible unique insoluble pair combinations even in the absence of any catalytic synthesis and that minimum total number of amino acids in the pair is 5. If weak enantioselective forward catalytic synthesis of amino acids is present, then the number of possible variants, in which chiral symmetry breaking may occur, increases substantially. It was shown that that the most interesting catalysts have zero or one amino acid of "incorrect" chirality. If the parameters of the model are adjusted in such a way to result in an increase of concentration of longer peptides, then catalysts with two amino acids of incorrect chirality start to appear at peptides of length five. Models of chiral symmetry breaking in the presence of epimerization were considered for peptides up to length three. It was shown that the range of parameters in which chiral symmetry breaking could occur significantly shrinks in comparison to previously considered models with peptides up to length two. An experiment of chiral symmetry breaking was proposed. The experiment consists of a three-step cycle: reversible catalytic synthesis of amino acids, reversible synthesis of peptides, and irreversible sedimentation of insoluble substances.

  11. Reversal time of jump-noise magnetization dynamics in nanomagnets via Monte Carlo simulations

    Science.gov (United States)

    Parthasarathy, Arun; Rakheja, Shaloo

    2018-06-01

    The jump-noise is a nonhomogeneous Poisson process which models thermal effects in magnetization dynamics, with special applications in low temperature escape rate phenomena. In this work, we develop improved numerical methods for Monte Carlo simulation of the jump-noise dynamics and validate the method by comparing the stationary distribution obtained empirically against the Boltzmann distribution. In accordance with the Néel-Brown theory, the jump-noise dynamics display an exponential relaxation toward equilibrium with a characteristic reversal time, which we extract for nanomagnets with uniaxial and cubic anisotropy. We relate the jump-noise dynamics to the equivalent Landau-Lifshitz dynamics up to second order correction for a general energy landscape and obtain the analogous Néel-Brown theory's solution of the reversal time. We find that the reversal time of jump-noise dynamics is characterized by Néel-Brown theory's solution at the energy saddle point for small noise. For large noise, the magnetization reversal due to jump-noise dynamics phenomenologically represents macroscopic tunneling of magnetization.

  12. Spontaneous reverse movement of mRNA-bound tRNA through the ribosome.

    Science.gov (United States)

    Konevega, Andrey L; Fischer, Niels; Semenkov, Yuri P; Stark, Holger; Wintermeyer, Wolfgang; Rodnina, Marina V

    2007-04-01

    During the translocation step of protein synthesis, a complex of two transfer RNAs bound to messenger RNA (tRNA-mRNA) moves through the ribosome. The reaction is promoted by an elongation factor, called EF-G in bacteria, which, powered by GTP hydrolysis, induces an open, unlocked conformation of the ribosome that allows for spontaneous tRNA-mRNA movement. Here we show that, in the absence of EF-G, there is spontaneous backward movement, or retrotranslocation, of two tRNAs bound to mRNA. Retrotranslocation is driven by the gain in affinity when a cognate E-site tRNA moves into the P site, which compensates the affinity loss accompanying the movement of peptidyl-tRNA from the P to the A site. These results lend support to the diffusion model of tRNA movement during translocation. In the cell, tRNA movement is biased in the forward direction by EF-G, which acts as a Brownian ratchet and prevents backward movement.

  13. Transducer frequency response variations investigated by time reversal calibration

    Czech Academy of Sciences Publication Activity Database

    Kober, Jan; Převorovský, Zdeněk

    2016-01-01

    Roč. 26, č. 2 (2016), A16-A16 ISSN 1213-3825. [Europen Conference on Acoustic Emission Testing /32./. 07.09.2016-09.09.2016, Praha] Institutional support: RVO:61388998 Keywords : calibration * time reversal * transducer * frequency response Subject RIV: BI - Acoustics

  14. Evaluation of the UP4FUN intervention: a cluster randomized trial to reduce and break up sitting time in European 10-12-year-old children.

    Directory of Open Access Journals (Sweden)

    Frøydis N Vik

    Full Text Available The UP4FUN intervention is a family-involved school-based intervention aiming at reducing and breaking up sitting time at home (with special emphasis on screen time, and breaking up sitting time in school among 10-12 year olds in Europe. The purpose of the present paper was to evaluate its short term effects.A total of 3147 pupils from Belgium, Germany, Greece, Hungary and Norway participated in a school-randomized controlled trial. The intervention included 1-2 school lessons per week for a period of six weeks, along with assignments for the children and their parents. Screen time and breaking up sitting time were registered by self-report and total sedentary time and breaking up sitting time by accelerometry. The effect of the intervention on these behaviors was evaluated by multilevel regression analyses. All analyses were adjusted for baseline values and gender. Significance level was p≤0.01. No significant intervention effects were observed, neither for self-reported TV/DVD or computer/game console time, nor for accelerometer-assessed total sedentary time and number of breaks in sitting time. The intervention group, however, reported more positive attitudes towards (β = 0.25 (95% CI 0.11, 0.38 and preferences/liking for (β = 0.20 (95% CI 0.08, 0.32 breaking up sitting time than the control group.No significant intervention effect on self-reported screen time or accelerometer-assessed sedentary time or breaks in sitting time was observed, but positive effects on beliefs regarding breaking up sitting time were found in favor of the intervention group. Overall, these results do not warrant wider dissemination of the present UP4FUN intervention.International Standard Randomized Controlled Trial Number Registry ISRCTN34562078.

  15. Mirror Symmetry Breaking and Restoration: The Role of Noise and Chiral Bias

    International Nuclear Information System (INIS)

    Hochberg, David

    2009-01-01

    The nonequilibrium effective potential is computed for the Frank model of spontaneous mirror symmetry breaking (SMSB) in chemistry in which external noise is introduced to account for random environmental effects. When these fluctuations exceed a critical magnitude, mirror symmetry is restored. The competition between ambient noise and the chiral bias due to physical fields and polarized radiation can be explored with this potential.

  16. Absence of Quantum Time Crystals.

    Science.gov (United States)

    Watanabe, Haruki; Oshikawa, Masaki

    2015-06-26

    In analogy with crystalline solids around us, Wilczek recently proposed the idea of "time crystals" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state or in the canonical ensemble of a general Hamiltonian, which consists of not-too-long-range interactions.

  17. Sugammadex: A Review of Neuromuscular Blockade Reversal.

    Science.gov (United States)

    Keating, Gillian M

    2016-07-01

    Sugammadex (Bridion(®)) is a modified γ-cyclodextrin that reverses the effect of the steroidal nondepolarizing neuromuscular blocking agents rocuronium and vecuronium. Intravenous sugammadex resulted in rapid, predictable recovery from moderate and deep neuromuscular blockade in patients undergoing surgery who received rocuronium or vecuronium. Recovery from moderate neuromuscular blockade was significantly faster with sugammadex 2 mg/kg than with neostigmine, and recovery from deep neuromuscular blockade was significantly faster with sugammadex 4 mg/kg than with neostigmine or spontaneous recovery. In addition, recovery from neuromuscular blockade was significantly faster when sugammadex 16 mg/kg was administered 3 min after rocuronium than when patients spontaneously recovered from succinylcholine. Sugammadex also demonstrated efficacy in various special patient populations, including patients with pulmonary disease, cardiac disease, hepatic dysfunction or myasthenia gravis and morbidly obese patients. Intravenous sugammadex was generally well tolerated. In conclusion, sugammadex is an important option for the rapid reversal of rocuronium- or vecuronium-induced neuromuscular blockade.

  18. Attenuation compensation in least-squares reverse time migration using the visco-acoustic wave equation

    KAUST Repository

    Dutta, Gaurav

    2013-08-20

    Attenuation leads to distortion of amplitude and phase of seismic waves propagating inside the earth. Conventional acoustic and least-squares reverse time migration do not account for this distortion which leads to defocusing of migration images in highly attenuative geological environments. To account for this distortion, we propose to use the visco-acoustic wave equation for least-squares reverse time migration. Numerical tests on synthetic data show that least-squares reverse time migration with the visco-acoustic wave equation corrects for this distortion and produces images with better balanced amplitudes compared to the conventional approach. © 2013 SEG.

  19. Unitarity and time reversal in the Glauber model

    International Nuclear Information System (INIS)

    Lazard, C.; Lombard, R.J.

    1984-12-01

    It has been pointed out by Formanek (1976-1980) that for incident energies above the particle production threshold the usual Glauber formulation of particle-nucleus scattering violates unitarity and time reversal invariance. We propose a simple method for recovering T-invariance and we discuss unitarity in view of the proposed modification. Numerical estimates are given to check the importance of T-invariance effects

  20. The brief time-reversibility of the local Lyapunov exponents for a small chaotic Hamiltonian system

    International Nuclear Information System (INIS)

    Waldner, Franz; Hoover, William G.; Hoover, Carol G.

    2014-01-01

    Highlights: •We consider the local Lyapunov spectrum for a four-dimensional Hamilton system. •Its stable periodic motion can be reversed for long times. •In the chaotic motion, time reversal occurs only for a short time. •Perturbations will change this short unstable case into a different stable case. •These observations might relate chaos to the Second Law of Thermodynamics. - Abstract: We consider the local (instantaneous) Lyapunov spectrum for a four-dimensional Hamiltonian system. Its stable periodic motion can be reversed for long times. Its unstable chaotic motion, with two symmetric pairs of exponents, cannot. In the latter case reversal occurs for more than a thousand fourth-order Runge–Kutta time steps, followed by a transition to a new set of paired Lyapunov exponents, unrelated to those seen in the forward time direction. The relation of the observed chaotic dynamics to the Second Law of Thermodynamics is discussed

  1. A model of intrinsic symmetry breaking

    International Nuclear Information System (INIS)

    Ge, Li; Li, Sheng; George, Thomas F.; Sun, Xin

    2013-01-01

    Different from the symmetry breaking associated with a phase transition, which occurs when the controlling parameter is manipulated across a critical point, the symmetry breaking presented in this Letter does not need parameter manipulation. Instead, the system itself suddenly undergoes symmetry breaking at a certain time during its evolution, which is intrinsic symmetry breaking. Through a polymer model, it is revealed that the origin of the intrinsic symmetry breaking is nonlinearity, which produces instability at the instance when the evolution crosses an inflexion point, where this instability breaks the original symmetry

  2. Reverse gyrase functions in genome integrity maintenance by protecting DNA breaks in vivo

    DEFF Research Database (Denmark)

    Han, Wenyuan; Feng, Xu; She, Qunxin

    2017-01-01

    Reverse gyrase introduces positive supercoils to circular DNA and is implicated in genome stability maintenance in thermophiles. The extremely thermophilic crenarchaeon Sulfolobus encodes two reverse gyrase proteins, TopR1 (topoisomerase reverse gyrase 1) and TopR2, whose functions in thermophilic...... and subsequent DNA degradation. The former occurred immediately after drug treatment, leading to chromosomal DNA degradation that concurred with TopR1 degradation, followed by chromatin protein degradation and DNA-less cell formation. To gain a further insight into TopR1 function, the expression of the enzyme...

  3. Connected Green function approach to symmetry breaking in Φ1+14-theory

    International Nuclear Information System (INIS)

    Haeuser, J.M.; Cassing, W.; Peter, A.; Thoma, M.H.

    1995-01-01

    Using the cluster expansions for n-point Green functions we derive a closed set of dynamical equations of motion for connected equal-time Green functions by neglecting all connected functions higher than 4 th order for the λΦ 4 -theory in 1+1 dimensions. We apply the equations to the investigation of spontaneous symmetry breaking, i.e. to the evaluation of the effective potential at temperature T=0. Within our momentum space discretization we obtain a second order phase transition (in agreement with the Simon-Griffith theorem) and a critical coupling of λ crit /4m 2 =2.446 ascompared to a first order phase transition and λ crit /4m 2 =2.568 from the Gaussian effective potential approach. (orig.)

  4. Fast damage imaging using the time-reversal technique in the frequency–wavenumber domain

    International Nuclear Information System (INIS)

    Zhu, R; Huang, G L; Yuan, F G

    2013-01-01

    The time-reversal technique has been successfully used in structural health monitoring (SHM) for quantitative imaging of damage. However, the technique is very time-consuming when it is implemented in the time domain. In this paper, we study the technique in the frequency–wavenumber (f–k) domain for fast real-time imaging of multiple damage sites in plates using scattered flexural plate waves. Based on Mindlin plate theory, the time reversibility of dispersive flexural waves in an isotropic plate is theoretically investigated in the f–k domain. A fast damage imaging technique is developed by using the cross-correlation between the back-propagated scattered wavefield and the incident wavefield in the frequency domain. Numerical simulations demonstrate that the proposed technique cannot only localize multiple damage sites but also potentially identify their sizes. Moreover, the time-reversal technique in the f–k domain is about two orders of magnitude faster than the method in the time domain. Finally, experimental testing of an on-line SHM system with a sparse piezoelectric sensor array is conducted for fast multiple damage identification using the proposed technique. (paper)

  5. Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale

    International Nuclear Information System (INIS)

    Gorbunov, Dmitry S.; Sibiryakov, Sergei M.

    2005-01-01

    We present an extension of the Randall-Sundrum model in which, due to spontaneous Lorentz symmetry breaking, graviton mixes with bulk vector fields and becomes quasilocalized. The masses of KK modes comprising the four-dimensional graviton are naturally exponentially small. This allows to push the Lorentz breaking scale to as high as a few tenth of the Planck mass. The model does not contain ghosts or tachyons and does not exhibit the van Dam-Veltman-Zakharov discontinuity. The gravitational attraction between static point masses becomes gradually weaker with increasing of separation and gets replaced by repulsion (antigravity) at exponentially large distances

  6. Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale

    Energy Technology Data Exchange (ETDEWEB)

    Gorbunov, Dmitry S. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect, 7a, 117312 Moscow (Russian Federation); Sibiryakov, Sergei M. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect, 7a, 117312 Moscow (Russian Federation)

    2005-09-15

    We present an extension of the Randall-Sundrum model in which, due to spontaneous Lorentz symmetry breaking, graviton mixes with bulk vector fields and becomes quasilocalized. The masses of KK modes comprising the four-dimensional graviton are naturally exponentially small. This allows to push the Lorentz breaking scale to as high as a few tenth of the Planck mass. The model does not contain ghosts or tachyons and does not exhibit the van Dam-Veltman-Zakharov discontinuity. The gravitational attraction between static point masses becomes gradually weaker with increasing of separation and gets replaced by repulsion (antigravity) at exponentially large distances.

  7. Are the Concepts of Dynamic Equilibrium and the Thermodynamic Criteria for Spontaneity, Nonspontaneity, and Equilibrium Compatible?

    Science.gov (United States)

    Silverberg, Lee J.; Raff, Lionel M.

    2015-01-01

    Thermodynamic spontaneity-equilibrium criteria require that in a single-reaction system, reactions in either the forward or reverse direction at equilibrium be nonspontaneous. Conversely, the concept of dynamic equilibrium holds that forward and reverse reactions both occur at equal rates at equilibrium to the extent allowed by kinetic…

  8. Time-reversal acoustics and ultrasound-assisted convection-enhanced drug delivery to the brain.

    Science.gov (United States)

    Olbricht, William; Sistla, Manjari; Ghandi, Gaurav; Lewis, George; Sarvazyan, Armen

    2013-08-01

    Time-reversal acoustics is an effective way of focusing ultrasound deep inside heterogeneous media such as biological tissues. Convection-enhanced delivery is a method of delivering drugs into the brain by infusing them directly into the brain interstitium. These two technologies are combined in a focusing system that uses a "smart needle" to simultaneously infuse fluid into the brain and provide the necessary feedback for focusing ultrasound using time-reversal acoustics. The effects of time-reversal acoustics-focused ultrasound on the spatial distribution of infused low- and high-molecular weight tracer molecules are examined in live, anesthetized rats. Results show that exposing the rat brain to focused ultrasound significantly increases the penetration of infused compounds into the brain. The addition of stabilized microbubbles enhances the effect of ultrasound exposure.

  9. Time-reversal focusing of an expanding soliton gas in disordered replicas

    KAUST Repository

    Fratalocchi, Andrea; Armaroli, A.; Trillo, S.

    2011-01-01

    We investigate the properties of time reversibility of a soliton gas, originating from a dispersive regularization of a shock wave, as it propagates in a strongly disordered environment. An original approach combining information measures and spin glass theory shows that time-reversal focusing occurs for different replicas of the disorder in forward and backward propagation, provided the disorder varies on a length scale much shorter than the width of the soliton constituents. The analysis is performed by starting from a new class of reflectionless potentials, which describe the most general form of an expanding soliton gas of the defocusing nonlinear Schrödinger equation.

  10. Time-reversal focusing of an expanding soliton gas in disordered replicas

    KAUST Repository

    Fratalocchi, Andrea

    2011-05-31

    We investigate the properties of time reversibility of a soliton gas, originating from a dispersive regularization of a shock wave, as it propagates in a strongly disordered environment. An original approach combining information measures and spin glass theory shows that time-reversal focusing occurs for different replicas of the disorder in forward and backward propagation, provided the disorder varies on a length scale much shorter than the width of the soliton constituents. The analysis is performed by starting from a new class of reflectionless potentials, which describe the most general form of an expanding soliton gas of the defocusing nonlinear Schrödinger equation.

  11. A model of spontaneous symmetry breakdown in spatially flat cosmological spacetimes

    International Nuclear Information System (INIS)

    Kundu, P.

    1984-01-01

    This paper is an elaboration of a previous short exposition of a theory of spontaneous symmetry breaking in a conformally coupled, massless lambdaphi 4 model in a spatially flat Robertson-Walker spacetime. Under the weakened global boundary condition allowing the physical spacetime to be conformal to only a portion of the Minkowski spacetime, the model admits a pair of degenerate vacua in which the phi->phi symmetry is spontaneously broken. The model is formulated as a euclidean field theory in a space with a positive-definite metric obtained by analytically continuing the conformal time coordinate. An appropriate time-dependent zero energy solution of the euclidean equation of motion representing the field configuration in the asymmetric vacuum is considered and the corresponding quantum trace anomaly is computed in the one-loop approximation. The nontrivial infrared behavior of the model due to the singular nature of the classical background field forces a modification of the boundary conditions on the propagator. A general form for an 'improved' one-loop trace anomaly is found by a simple argument based on renormalization group invariance. Via the Einstein equation, the trace anomaly leads to a self-consistent dynamical equation for the cosmic expansion scale factor. Some physical aspects of the back-reaction problem based on a simple power law model of the expansion scale factor are discussed. (orig.)

  12. Multiples least-squares reverse time migration

    KAUST Repository

    Zhang, Dongliang

    2013-01-01

    To enhance the image quality, we propose multiples least-squares reverse time migration (MLSRTM) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. Since each recorded trace is treated as a virtual source, knowledge of the source wavelet is not required. Numerical tests on synthetic data for the Sigsbee2B model and field data from Gulf of Mexico show that MLSRTM can improve the image quality by removing artifacts, balancing amplitudes, and suppressing crosstalk compared to standard migration of the free-surface multiples. The potential liability of this method is that multiples require several roundtrips between the reflector and the free surface, so that high frequencies in the multiples are attenuated compared to the primary reflections. This can lead to lower resolution in the migration image compared to that computed from primaries.

  13. Dynamical Symmetry Breaking of Extended Gauge Symmetries

    OpenAIRE

    Appelquist, Thomas; Shrock, Robert

    2003-01-01

    We construct asymptotically free gauge theories exhibiting dynamical breaking of the left-right, strong-electroweak gauge group $G_{LR} = {\\rm SU}(3)_c \\times {\\rm SU}(2)_L \\times {\\rm SU}(2)_R \\times {\\rm U}(1)_{B-L}$, and its extension to the Pati-Salam gauge group $G_{422}={\\rm SU}(4)_{PS} \\times {\\rm SU}(2)_L \\times {\\rm SU}(2)_R$. The models incorporate technicolor for electroweak breaking, and extended technicolor for the breaking of $G_{LR}$ and $G_{422}$ and the generation of fermion ...

  14. Symmetry breaking in superstring theories: applications in cosmology and particle physics

    International Nuclear Information System (INIS)

    Catelin-Julien, T.

    2008-10-01

    This thesis is devoted to the study of some applications of superstring theory in cosmology and in particle physics. The unifying principle of our work is the stringy spontaneous (super)symmetry breaking mechanism. Our manuscript starts with a general overview of string theory, where the emphasis is put on the aspects that will be important throughout our work. We introduce then our first work, in which we exhibit a new symmetry of the vacua of N = 1 heterotic string theory, exchanging the vectorial and spinorial representations of the grand unified gauge group. In a second part, we consider stringy cosmological evolutions, at non-zero temperature and in the presence of a supersymmetry breaking scale. We also give arguments for a stabilization of the compactification moduli. (author)

  15. The double-slit experiment and the time-reversed fire alarm

    International Nuclear Information System (INIS)

    Halabi, T.

    2010-01-01

    When both slits of the double-slit experiment are open, closing one paradoxically increases the detection rate at some points on the detection screen. Feynman famously warned that temptation to understand such a puzzling feature only draws into blind alleys. Nevertheless, we gain insight into this feature by drawing an analogy between the double-slit experiment and a time-reversed fire alarm. Much as closing the slit increases probability of a future detection, ruling out fire drill scenarios, having heard the fire alarm, increases probability of a past fire (using Bayesian inference). Classically, Bayesian inference is associated with computing probabilities of past events. We therefore identify this feature of the double-slit experiment with a time-reversed thermodynamic arrow. We believe that much of the enigma of quantum mechanics is simply due to some variation of time's arrow. In further support of this, we employ a plausible formulation of the thermodynamic arrow to derive an uncertainty in classical mechanics that is reminiscent of quantum uncertainty.

  16. Osteonecrosis or spontaneous fractures following renal transplantation

    International Nuclear Information System (INIS)

    Andresen, J.; Nielsen, H.E.; Aarhus Univ.

    1981-01-01

    31 renal transplant recipients with posttransplant development of osteonecrosis or spontaneous fractures were evaluated with regard to age, duration of dialysis before transplantation. Determination of metacarpal bone mass at the time of transplantation and registration of bone resorption and soft tissue calcification at the time of transplantation and at the time of onset of osteonecrosis and spontaneous fractures were made. Apart from the increased mean age in patients with spontaneous fractures no difference was seen between the groups. Osteonecrosis and spontaneous fractures occurred in areas of trabecular bone. It seems most likely that after renal transplantation the patients show bone complications of different localization. (orig.) [de

  17. Low serum hyaluronic acid levels associated with spontaneous HBsAg clearance

    NARCIS (Netherlands)

    Harkisoen, S.; Arends, J. E.; van den Hoek, A.; van Erpecum, K. J.; Boland, G. J.; Hoepelman, A. I. M.

    2015-01-01

    Purpose The pathophysiological underlying mechanism of spontaneous HBsAg clearance in hepatitis B virus (HBV) infected patients is largely unknown. However, serum hyaluronic acid (sHA) plays a role in liver fibrosis progression and reversely could serve as a potential biomarker for HBsAg clearance.

  18. Assessing the benefits of napping and short rest breaks on processing speed in sleep-restricted adolescents.

    Science.gov (United States)

    Lim, Julian; Lo, June C; Chee, Michael W L

    2017-04-01

    Achievement-oriented adolescents often study long hours under conditions of chronic sleep restriction, adversely affecting cognitive function. Here, we studied how napping and rest breaks (interleaved off-task periods) might ameliorate the negative effects of sleep restriction on processing speed. Fifty-seven healthy adolescents (26 female, age = 15-19 years) participated in a 15-day live-in protocol. All participants underwent sleep restriction (5 h time-in-bed), but were then randomized into two groups: one of these groups received a daily 1-h nap opportunity. Data from seven of the study days (sleep restriction days 1-5, and recovery days 1-2) are reported here. The Blocked Symbol Decoding Test, administered once a day, was used to assess time-on-task effects and the effects of rest breaks on processing speed. Controlling for baseline differences, participants who took a nap demonstrated faster speed of processing and greater benefit across testing sessions from practice. These participants were also affected significantly less by time-on-task effects. In contrast, participants who did not receive a nap benefited more from the rest breaks that were permitted between blocks of the test. Our results indicate that napping partially reverses the detrimental effects of sleep restriction on processing speed. However, rest breaks have a greater effect as a countermeasure against poor performance when sleep pressure is higher. These data add to the growing body of evidence showing the importance of sleep for good cognitive functioning in adolescents, and suggest that more frequent rest breaks might be important in situations where sleep loss is unavoidable. © 2017 European Sleep Research Society.

  19. Low Scale Supersymmetry Breaking and its LHC Signatures

    CERN Document Server

    Dudas, Emilian; Tziveloglou, Pantelis

    2013-01-01

    We study the most general extension of the MSSM Lagrangian that includes scenarios in which supersymmetry is spontaneously broken at a low scale f. The spurion that parametrizes supersymmetry breaking in the MSSM is promoted to a dynamical superfield involving the goldstino, with (and without) its scalar superpartner, the sgoldstino. The low energy effective Lagrangian is written as an expansion in terms of m_{SUSY}/sqrt{f}, where m_{SUSY} is the induced supersymmetry breaking scale, and contains, in addition to the usual MSSM Lagrangian with the soft terms, couplings involving the component fields of the goldstino superfield and the MSSM fields. This Lagrangian can provide significant corrections to the usual couplings in the Standard Model and the MSSM. We study how these new corrections affect the Higgs couplings to gauge bosons and fermions, and how LHC bounds can be used in order to constrain f. We also discuss that, from the effective field theory point of view, the couplings of the goldstino interactio...

  20. Reversible Mechanochemistry of a PdII Coordination Polymer

    NARCIS (Netherlands)

    Paulusse, Jos Marie Johannes; Sijbesma, Rint P.

    2004-01-01

    Breaking up and making up: The ultrasonic cleavage of high-molecular-weight linear coordination polymers of phosphane telechelic polytetrahydrofuran and palladium dichloride in dilute solution is a reversible process (see picture). Sonication for 1 h led to a decrease in the weight-averaged

  1. Time reversal signal processing in acoustic emission testing

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Krofta, Josef; Kober, Jan; Dvořáková, Zuzana; Chlada, Milan; Dos Santos, S.

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : acoustic emission (AE) * ultrasonic testing (UT) * signal processing * source location * time reversal acoustic s * acoustic emission * signal processing and transfer Subject RIV: BI - Acoustic s http://www.ndt.net/events/ECNDT2014/app/content/Slides/637_Prevorovsky.pdf

  2. Why older adults spend time sedentary and break their sedentary behaviour: a mixed methods approach using life-logging equipment

    Directory of Open Access Journals (Sweden)

    Manon L Dontje

    2015-10-01

    It can be concluded that a mixed methods approach, by combining objective data of an activity monitor with contextual information from time-lapse photos and subjective information from people regarding their own behaviour, is an useful method to provide indepth information about (breaking sedentary behaviour in older adults. The results of this study showed that there is a difference in what older adults believe that are reasons for them to remain sedentary or break their sedentary time and what their actual reasons are. A personal story board based on objective measurements of sedentary behaviour can be a useful method to raise awareness and find individual and tailored ways to reduce sedentary behaviour and to increase the number of breaks in sedentary behaviour without much interference in daily routine.

  3. Association of sitting time and breaks in sitting with muscle mass, strength, function, and inflammation in community-dwelling older adults.

    Science.gov (United States)

    Reid, N; Healy, G N; Gianoudis, J; Formica, M; Gardiner, P A; Eakin, E E; Nowson, C A; Daly, R M

    2018-02-26

    The mechanisms through which excessive sitting time impacts health are important to understand. This study found that each hour of sitting per day was not associated with physical function, although associations with poor body composition were observed. Reducing sitting time for improved weight management in older adults needs further exploration. To examine the association of sitting time and breaks in sitting time with muscle mass, strength, function, and inflammation in older Australians. Data from the thigh-worn activPAL3™ monitor (7-day continuous wear) was used to derive time spent sitting (hours) and total number of sit-stand transitions per day. Body composition (dual energy X-ray absorptiometry), lower-body muscle strength, function (timed up-and-go [TUG], 4-m gait speed, four square step test, 30-second sit-to-stand), and serum inflammatory markers (interleukin-[IL-6], IL-8, IL-10, tumor necrosis factor-alpha [TNF-α], and adiponectin) were measured. Multiple regression analyses, adjusted for age, sex, ethnicity, education, employment status, marital status, number of prescription medications, smoking status, vitamin D, and stepping time, were used to assess the associations. Data from 123 community-dwelling older adults (aged 65-84 years, 63% female) were used. Total daily sitting time was associated with lower percentage lean mass (β [95%CI], - 1.70% [- 2.30, - 1.10]) and higher total body fat mass (2.92 kg [1.94, 3.30]). More frequent breaks in sitting time were associated with a 45% reduced risk of having pre-sarcopenia (OR = 0.55; 95% CI 0.34, 0.91; model 1), defined as appendicular lean mass divided by BMI. No significant associations were observed for sitting time or breaks in sitting with measures of muscle strength, function, or inflammation. In older community-dwelling adults, greater sitting time was associated with a lower percentage lean mass, while more frequent breaks in sitting time were associated with lower odds of having

  4. Classical reconstruction of interference patterns of position-wave-vector-entangled photon pairs by the time-reversal method

    Science.gov (United States)

    Ogawa, Kazuhisa; Kobayashi, Hirokazu; Tomita, Akihisa

    2018-02-01

    The quantum interference of entangled photons forms a key phenomenon underlying various quantum-optical technologies. It is known that the quantum interference patterns of entangled photon pairs can be reconstructed classically by the time-reversal method; however, the time-reversal method has been applied only to time-frequency-entangled two-photon systems in previous experiments. Here, we apply the time-reversal method to the position-wave-vector-entangled two-photon systems: the two-photon Young interferometer and the two-photon beam focusing system. We experimentally demonstrate that the time-reversed systems classically reconstruct the same interference patterns as the position-wave-vector-entangled two-photon systems.

  5. Nonlinear Time Reversal Acoustic Method of Friction Stir Weld Assessment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project is demonstration of the feasibility of Friction Stir Weld (FSW) assessment by novel Nonlinear Time Reversal Acoustic (TRA) method. Time...

  6. The timing of spontaneous detection and repair of naming errors in aphasia.

    Science.gov (United States)

    Schuchard, Julia; Middleton, Erica L; Schwartz, Myrna F

    2017-08-01

    This study examined the timing of spontaneous self-monitoring in the naming responses of people with aphasia. Twelve people with aphasia completed a 615-item naming test twice, in separate sessions. Naming attempts were scored for accuracy and error type, and verbalizations indicating detection were coded as negation (e.g., "no, not that") or repair attempts (i.e., a changed naming attempt). Focusing on phonological and semantic errors, we measured the timing of the errors and of the utterances that provided evidence of detection. The effects of error type and detection response type on error-to-detection latencies were analyzed using mixed-effects regression modeling. We first asked whether phonological errors and semantic errors differed in the timing of the detection process or repair planning. Results suggested that the two error types primarily differed with respect to repair planning. Specifically, repair attempts for phonological errors were initiated more quickly than repair attempts for semantic errors. We next asked whether this difference between the error types could be attributed to the tendency for phonological errors to have a high degree of phonological similarity with the subsequent repair attempts, thereby speeding the programming of the repairs. Results showed that greater phonological similarity between the error and the repair was associated with faster repair times for both error types, providing evidence of error-to-repair priming in spontaneous self-monitoring. When controlling for phonological overlap, significant effects of error type and repair accuracy on repair times were also found. These effects indicated that correct repairs of phonological errors were initiated particularly quickly, whereas repairs of semantic errors were initiated relatively slowly, regardless of their accuracy. We discuss the implications of these findings for theoretical accounts of self-monitoring and the role of speech error repair in learning. Copyright

  7. [Comparison of neostigmine induced reversal of rocuronium in different age children].

    Science.gov (United States)

    Liu, Jinzhu; Cheng, Zhaoyu

    2016-03-15

    To compare the effectiveness of neostigmine induced reversal of rocuronium in neonates, infants, young children and children. One hundred and sixty ASA I or II pediatric patients undergoings elective surgical procedures under total intravenous anesthesia were enrolled during July 2014 to April 2015 in Tianjin Children's Hospital. The patients were divided into four groups according to ages: neonate group, infant group, young children group and children group.Then control subgroup and neostigmine reversal subgroup including twenty patients were randomly selected from every different age groups by the method of random number table. After induction of anesthesia, 0.6 mg/kg rocuronium was administered, and 0.2 mg/kg maintenance doses given as required during period of operation. Neuromuscular block was monitored using acceleromyographic train of four (TOF). When T1/control returned to 15%, 0.03 mg/kg neostigmine and 0.01 mg/kg atropine were given to patients of reversal subgroups, and saline 0.1 ml/kg was given to patients of control subgroups. The recovery time of T25, T75, TR0.7, recovery index, blood pressure, heart rate and adverse reactions were observed and recorded. In control subgroups, the recovery time of T75 for neonates, infants, young children and children were (27.10±8.72), (16.70±6.35), (13.05±1.96), (14.40±3.08) min, respectively (F=25.052, P0.05). But the recovery time of T75, TR0.7 and recovery index in neonate group were longer than other age groups (all Procuronium are comparable in infant, young children and children. There are obviously reversal effects in all of age groups when neostigmine is given to antagonize rocuronium. Either spontaneous recovery time or reversal recovery time of neostigmine to rocuronium is longer for neonates than other age's children.

  8. The effect of interruptions and breaks on insight and impasses: Do you need a break right now?

    NARCIS (Netherlands)

    Beeftink, F.; van Eerde, W.; Rutte, C.G.

    2008-01-01

    Some time away from a problem, or incubation time, is found to be beneficial to creative problem solving. But are interruptions as equally helpful as breaks? An experiment was conducted to gain more insight into the differences between imposed and self-initiated breaks, and their effects on

  9. Ultrasound breast imaging using frequency domain reverse time migration

    Science.gov (United States)

    Roy, O.; Zuberi, M. A. H.; Pratt, R. G.; Duric, N.

    2016-04-01

    Conventional ultrasonography reconstruction techniques, such as B-mode, are based on a simple wave propagation model derived from a high frequency approximation. Therefore, to minimize model mismatch, the central frequency of the input pulse is typically chosen between 3 and 15 megahertz. Despite the increase in theoretical resolution, operating at higher frequencies comes at the cost of lower signal-to-noise ratio. This ultimately degrades the image contrast and overall quality at higher imaging depths. To address this issue, we investigate a reflection imaging technique, known as reverse time migration, which uses a more accurate propagation model for reconstruction. We present preliminary simulation results as well as physical phantom image reconstructions obtained using data acquired with a breast imaging ultrasound tomography prototype. The original reconstructions are filtered to remove low-wavenumber artifacts that arise due to the inclusion of the direct arrivals. We demonstrate the advantage of using an accurate sound speed model in the reverse time migration process. We also explain how the increase in computational complexity can be mitigated using a frequency domain approach and a parallel computing platform.

  10. Estimating medication stopping fraction and real-time prevalence of drug use in pharmaco-epidemiologic databases. An application of the reverse waiting time distribution

    DEFF Research Database (Denmark)

    Støvring, Henrik; Pottegård, Anton; Hallas, Jesper

    2017-01-01

    Purpose: To introduce the reverse waiting time distribution (WTD) and show how it can be used to estimate stopping fractions and real-time prevalence of treatment in pharmacoepidemiological studies. Methods: The reverse WTD is the distribution of time from the last dispensed prescription of each......-hoc decision rules for automated implementations, and it yields estimates of real-time prevalence....... patient within a time window to the end of it. It is a mirrored version of the ordinary WTD, which considers the first dispensed prescription of patients within a time window. Based on renewal process theory, the reverse WTD can be analyzed as an ordinary WTD with maximum likelihood estimation. Based...

  11. Agrammatic aphasia verb and argument patterns in Kiswahili-English spontaneous language

    Directory of Open Access Journals (Sweden)

    Hillary K. Sang

    2015-06-01

    Full Text Available Background: The spontaneous and narrative language of Kiswahili agrammatic aphasic and non-brain-damaged speakers was analysed. The bilingual participants were also tested in English to enable comparisons of verb production in the two languages. The significance of this study was to characterise bilingual Kiswahili-English spontaneous agrammatic output. This was done by describing Kiswahili-English bilingual output data with a specific focus on the production of verbs. The description involves comparison of verb and argument production in Kiswahili and English. Methods and procedures: The participants recruited for this study were drawn from two groups of participants (six non-fluent aphasic/agrammatic speakers and six non-braindamaged. From each participant, a sample of spontaneous output was tape-recorded in English and Kiswahili based on the description and narration of the Flood rescue picture’ and the ‘Cookie theft picture’. The data elicited were compared for each subject and between the participants and relevant verb parameters have been analysed. The variables that were studied included mean length of utterance (MLU, inflectional errors, verb tokens and types, copulas and auxiliaries. Further, all verbs produced were classified as per their argument structure. Results: The results from English data supported previous findings on agrammatic output. The agrammatic participants produced utterances with shorter MLU and simpler sentence structure. However, Kiswahili data surprisingly showed reversed results, with agrammatic speakers producing longer utterances than non-brain-damaged (NBD controls. The results also revealed selective impairment in some agrammatic speakers who made inflectional errors. The verb argument structure showed contrasting results, with agrammatic speakers preferring transitive verbs whilst the NBD speakers used more intransitive verbs. Conclusions: The study attempts for the first time to characterise English

  12. Time-reversibility in seismic sequences: Application to the seismicity of Mexican subduction zone

    Science.gov (United States)

    Telesca, L.; Flores-Márquez, E. L.; Ramírez-Rojas, A.

    2018-02-01

    In this paper we investigate the time-reversibility of series associated with the seismicity of five seismic areas of the subduction zone beneath the Southwest Pacific Mexican coast, applying the horizontal visibility graph method to the series of earthquake magnitudes, interevent times, interdistances and magnitude increments. We applied the Kullback-Leibler divergence D that is a metric for quantifying the degree of time-irreversibility in time series. Our findings suggest that among the five seismic areas, Jalisco-Colima is characterized by time-reversibility in all the four seismic series. Our results are consistent with the peculiar seismo-tectonic characteristics of Jalisco-Colima, which is the closest to the Middle American Trench and belongs to the Mexican volcanic arc.

  13. The Tayler instability at low magnetic Prandtl numbers: between chiral symmetry breaking and helicity oscillations

    International Nuclear Information System (INIS)

    Weber, Norbert; Galindo, Vladimir; Stefani, Frank; Weier, Tom

    2015-01-01

    The Tayler instability is a kink-type, current driven instability that plays an important role in plasma physics but might also be relevant in liquid metal applications with high electrical currents. In the framework of the Tayler–Spruit dynamo model of stellar magnetic field generation (Spruit 2002 Astron. Astrophys. 381 923–32), the question of spontaneous helical (chiral) symmetry breaking during the saturation of the Tayler instability has received considerable interest (Zahn et al 2007 Astron. Astrophys. 474 145–54; Gellert et al 2011 Mon. Not. R. Astron. Soc. 414 2696–701; Bonanno et al 2012 Phys. Rev. E 86 016313). Focusing on fluids with low magnetic Prandtl numbers, for which the quasistatic approximation can be applied, we utilize an integro-differential equation approach (Weber et al 2013 New J. Phys.15 043034) in order to investigate the saturation mechanism of the Tayler instability. Both the exponential growth phase and the saturated phase are analysed in terms of the action of the α and β effects of mean-field magnetohydrodynamics. In the exponential growth phase we always find a spontaneous chiral symmetry breaking which, however, disappears in the saturated phase. For higher degrees of supercriticality, we observe helicity oscillations in the saturated regime. For Lundquist numbers in the order of one we also obtain chiral symmetry breaking of the saturated magnetic field. (paper)

  14. Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    He, Q.; Chu, Y. H.; Heron, J. T.; Yang, S. Y.; Wang, C. H.; Kuo, C. Y.; Lin, H. J.; Yu, P.; Liang, C. W.; Zeches, R. J.; Chen, C. T.; Arenholz, E.; Scholl, A.; Ramesh, R.

    2010-08-02

    The emergence of enhanced spontaneous magnetic moments in self-assembled, epitaxial nanostructures of tetragonal (T-phase) and rhombohedral phases (R-phase) of the multiferroic BiFeO{sub 3} system is demonstrated. X-ray magnetic circular dichroism based photoemission electron microscopy (PEEM) was applied to investigate the local nature of this magnetism. We find that the spontaneous magnetization of the R-phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent T-phase and the epitaxial constraint. Reversible electric field control and manipulation of this magnetic moment at room temperature is shown using a combination of piezoresponse force microscopy and PEEM studies.

  15. Discover potential in a search for time-reversal invariance violation in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gudkov, Vladimir, E-mail: gudkov@sc.edu; Song, Young-Ho [University of South Carolina, Department of Physics and Astronomy (United States)

    2013-03-15

    Time reversal invariance violating (TRIV) effects in low energy physics could be very important in searching for new physics, being complementary to neutron and atomic electric dipole moment (EDM) measurements. In this relation, we discuss a sensitivity of some TRIV observables to different models of time-reversal (CP) violation and their dependencies on nuclear structure. As a measure of a sensitivity of TRIV effects to the value of TRIV nucleon coupling constant, we introduce a coefficient of a 'discovery potential', which shows a possible factor for improving the current limits of the EDM experiments by measuring nuclear TRIV effects.

  16. Alcohol consumption at the time of conception and spontaneous abortion

    DEFF Research Database (Denmark)

    Henriksen, T.B.; Hjollund, N.H.; Jensen, Tina Kold

    2004-01-01

    The authors studied the association between female and male alcohol intakes at the time of conception and the risk of spontaneous abortion, including early pregnancy loss detected by urinary human chorionic gonadotropin. After a nationwide mailing to about 50,000 members of four trade unions...... in Denmark in 1992-1994, 430 couples without previous pregnancy attempts were enrolled when birth control was discontinued, and they were followed until a clinically recognized pregnancy or for six menstrual cycles. Alcohol intake and potential confounding factors were reported in monthly questionnaires...... with no intake were statistically significant. Both male and female alcohol intakes during the week of conception increased the risk of early pregnancy loss....

  17. Reversible Congenital Hypogonadotropic Hypogonadism in Patients with CHD7, FGFR1 or GNRHR Mutations

    Science.gov (United States)

    Laitinen, Eeva-Maria; Tommiska, Johanna; Sane, Timo; Vaaralahti, Kirsi; Toppari, Jorma; Raivio, Taneli

    2012-01-01

    Background Congenital hypogonadotropic hypogonadism (HH) is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH) have common phenotypic or genotypic features. Methods and Findings Thirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; n = 26) or normal sense of smell (nHH; n = 6) were enrolled (age range, 18–61 yrs). The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH) were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21–39 yrs). All had spontaneous testicular growth while on testosterone replacement therapy (TRT). One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q), which was accompanied by another GNRHR mutation (R139H or del309F). In addition, both of the KS patients had a mutation in CHD7 (p.Q51X) or FGFR1 (c.91+2T>A). Conclusions Considerable proportion of patients with HH (8% of KS probands) may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal. PMID:22724017

  18. Reversible congenital hypogonadotropic hypogonadism in patients with CHD7, FGFR1 or GNRHR mutations.

    Directory of Open Access Journals (Sweden)

    Eeva-Maria Laitinen

    Full Text Available BACKGROUND: Congenital hypogonadotropic hypogonadism (HH is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH have common phenotypic or genotypic features. METHODS AND FINDINGS: Thirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; n = 26 or normal sense of smell (nHH; n = 6 were enrolled (age range, 18-61 yrs. The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21-39 yrs. All had spontaneous testicular growth while on testosterone replacement therapy (TRT. One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q, which was accompanied by another GNRHR mutation (R139H or del309F. In addition, both of the KS patients had a mutation in CHD7 (p.Q51X or FGFR1 (c.91+2T>A. CONCLUSIONS: Considerable proportion of patients with HH (8% of KS probands may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal.

  19. Non-Abelian parafermions in time-reversal-invariant interacting helical systems

    Science.gov (United States)

    Orth, Christoph P.; Tiwari, Rakesh P.; Meng, Tobias; Schmidt, Thomas L.

    2015-02-01

    The interplay between bulk spin-orbit coupling and electron-electron interactions produces umklapp scattering in the helical edge states of a two-dimensional topological insulator. If the chemical potential is at the Dirac point, umklapp scattering can open a gap in the edge state spectrum even if the system is time-reversal invariant. We determine the zero-energy bound states at the interfaces between a section of a helical liquid which is gapped out by the superconducting proximity effect and a section gapped out by umklapp scattering. We show that these interfaces pin charges which are multiples of e /2 , giving rise to a Josephson current with 8 π periodicity. Moreover, the bound states, which are protected by time-reversal symmetry, are fourfold degenerate and can be described as Z4 parafermions. We determine their braiding statistics and show how braiding can be implemented in topological insulator systems.

  20. Observation of a Time Quasicrystal and Its Transition to a Superfluid Time Crystal

    Science.gov (United States)

    Autti, S.; Eltsov, V. B.; Volovik, G. E.

    2018-05-01

    We report experimental realization of a quantum time quasicrystal and its transformation to a quantum time crystal. We study Bose-Einstein condensation of magnons, associated with coherent spin precession, created in a flexible trap in superfluid 3He-B . Under a periodic drive with an oscillating magnetic field, the coherent spin precession is stabilized at a frequency smaller than that of the drive, demonstrating spontaneous breaking of discrete time translation symmetry. The induced precession frequency is incommensurate with the drive, and hence, the obtained state is a time quasicrystal. When the drive is turned off, the self-sustained coherent precession lives a macroscopically long time, now representing a time crystal with broken symmetry with respect to continuous time translations. Additionally, the magnon condensate manifests spin superfluidity, justifying calling the obtained state a time supersolid or a time supercrystal.

  1. Test of feasibility of a novel high precision test of time reversal invariance

    International Nuclear Information System (INIS)

    Samuel, Deepak

    2007-01-01

    The first results of a feasibility test of a novel high precision test of time reversal invariance are reported. The Time Reversal Invariance test at COSY (TRIC) was planned to measure the time reversal violating observable A y,xz with an accuracy of 10 -6 in proton-deuteron (p-d) scattering. A novel technique for measuring total cross sections is introduced and the achievable precision of this measuring technique is tested. The correlation coefficient A y,y in p-d scattering fakes a time-reversal violating effect. This work reports the feasibility test of the novel method in the measurement of A y,y in p-p scattering. The first step in the experimental design was the development of a hard real-time data acquisition system. To meet stringent latency requirements, the capabilities of Windows XP had to be augmented with a real-time subsystem. The remote control feature of the data acquisition enables users to operate it from any place via an internet connection. The data acquisition proved its reliability in several beam times without any failures. The analysis of the data showed the presence of 1/f noise which substantially limits the quality of our measurements. The origin of 1/f noise was traced and found to be the Barkhausen noise from the ferrite core of the beam current transformer (BCT). A global weighted fitting technique based on a modified Wiener-Khinchin method was developed and used to suppress the influence of 1/f noise, which increased the error bar of the results by a factor 3. This is the only deviation from our expectations. The results are presented and discussed. (orig.)

  2. Test of feasibility of a novel high precision test of time reversal invariance

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Deepak

    2007-07-01

    The first results of a feasibility test of a novel high precision test of time reversal invariance are reported. The Time Reversal Invariance test at COSY (TRIC) was planned to measure the time reversal violating observable A{sub y,xz} with an accuracy of 10{sup -6} in proton-deuteron (p-d) scattering. A novel technique for measuring total cross sections is introduced and the achievable precision of this measuring technique is tested. The correlation coefficient A{sub y,y} in p-d scattering fakes a time-reversal violating effect. This work reports the feasibility test of the novel method in the measurement of A{sub y,y} in p-p scattering. The first step in the experimental design was the development of a hard real-time data acquisition system. To meet stringent latency requirements, the capabilities of Windows XP had to be augmented with a real-time subsystem. The remote control feature of the data acquisition enables users to operate it from any place via an internet connection. The data acquisition proved its reliability in several beam times without any failures. The analysis of the data showed the presence of 1/f noise which substantially limits the quality of our measurements. The origin of 1/f noise was traced and found to be the Barkhausen noise from the ferrite core of the beam current transformer (BCT). A global weighted fitting technique based on a modified Wiener-Khinchin method was developed and used to suppress the influence of 1/f noise, which increased the error bar of the results by a factor 3. This is the only deviation from our expectations. The results are presented and discussed. (orig.)

  3. Regulating the Access to Awareness: Brain Activity Related to Probe-related and Spontaneous Reversals in Binocular Rivalry.

    Science.gov (United States)

    Metzger, Brian A; Mathewson, Kyle E; Tapia, Evelina; Fabiani, Monica; Gratton, Gabriele; Beck, Diane M

    2017-06-01

    Research on the neural correlates of consciousness (NCC) has implicated an assortment of brain regions, ERP components, and network properties associated with visual awareness. Recently, the P3b ERP component has emerged as a leading NCC candidate. However, typical P3b paradigms depend on the detection of some stimulus change, making it difficult to separate brain processes elicited by the stimulus itself from those associated with updates or changes in visual awareness. Here we used binocular rivalry to ask whether the P3b is associated with changes in awareness even in the absence of changes in the object of awareness. We recorded ERPs during a probe-mediated binocular rivalry paradigm in which brief probes were presented over the image in either the suppressed or dominant eye to determine whether the elicited P3b activity is probe or reversal related. We found that the timing of P3b (but not its amplitude) was closely related to the timing of the report of a perceptual change rather than to the onset of the probe. This is consistent with the proposal that P3b indexes updates in conscious awareness, rather than being related to stimulus processing per se. Conversely, the probe-related P1 amplitude (but not its latency) was associated with reversal latency, suggesting that the degree to which the probe is processed increases the likelihood of a fast perceptual reversal. Finally, the response-locked P3b amplitude (but not its latency) was associated with the duration of an intermediate stage between reversals in which parts of both percepts coexist (piecemeal period). Together, the data suggest that the P3b reflects an update in consciousness and that the intensity of that process (as indexed by P3b amplitude) predicts how immediate that update is.

  4. Rethinking spontaneous giving: Extreme time pressure and ego-depletion favor self-regarding reactions.

    Science.gov (United States)

    Capraro, Valerio; Cococcioni, Giorgia

    2016-06-02

    Previous experimental studies suggest that cooperation in one-shot anonymous interactions is, on average, spontaneous, rather than calculative. To explain this finding, it has been proposed that people internalize cooperative heuristics in their everyday life and bring them as intuitive strategies in new and atypical situations. Yet, these studies have important limitations, as they promote intuitive responses using weak time pressure or conceptual priming of intuition. Since these manipulations do not deplete participants' ability to reason completely, it remains unclear whether cooperative heuristics are really automatic or they emerge after a small, but positive, amount of deliberation. Consistent with the latter hypothesis, we report two experiments demonstrating that spontaneous reactions in one-shot anonymous interactions tend to be egoistic. In doing so, our findings shed further light on the cognitive underpinnings of cooperation, as they suggest that cooperation in one-shot interactions is not automatic, but appears only at later stages of reasoning.

  5. Rethinking spontaneous giving: Extreme time pressure and ego-depletion favor self-regarding reactions

    Science.gov (United States)

    Capraro, Valerio; Cococcioni, Giorgia

    2016-01-01

    Previous experimental studies suggest that cooperation in one-shot anonymous interactions is, on average, spontaneous, rather than calculative. To explain this finding, it has been proposed that people internalize cooperative heuristics in their everyday life and bring them as intuitive strategies in new and atypical situations. Yet, these studies have important limitations, as they promote intuitive responses using weak time pressure or conceptual priming of intuition. Since these manipulations do not deplete participants’ ability to reason completely, it remains unclear whether cooperative heuristics are really automatic or they emerge after a small, but positive, amount of deliberation. Consistent with the latter hypothesis, we report two experiments demonstrating that spontaneous reactions in one-shot anonymous interactions tend to be egoistic. In doing so, our findings shed further light on the cognitive underpinnings of cooperation, as they suggest that cooperation in one-shot interactions is not automatic, but appears only at later stages of reasoning. PMID:27251762

  6. Some factors affecting time reversal signal reconstruction

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Kober, Jan

    2015-01-01

    Roč. 70, September (2015), s. 604-608 ISSN 1875-3892. [ICU International Congress on Ultrasonics 2015. Metz, 10.05.2015-15.05.2015] Institutional support: RVO:61388998 Keywords : nondestructive testing * time reversal signal processing * ultrasonic source reconstruction * acoustic emission * coda wave interferometry Subject RIV: BI - Acoustic s http://ac.els-cdn.com/S1875389215007762/1-s2.0-S1875389215007762-main.pdf?_tid=1513a4a2-9e5b-11e5-9693-00000aab0f27&acdnat=1449655153_455a4e32a1135236d0796c3f973ff58e

  7. A Perspective for Time-Varying Channel Compensation with Model-Based Adaptive Passive Time-Reversal

    Directory of Open Access Journals (Sweden)

    Lussac P. MAIA

    2015-06-01

    Full Text Available Underwater communications mainly rely on acoustic propagation which is strongly affected by frequency-dependent attenuation, shallow water multipath propagation and significant Doppler spread/shift induced by source-receiver-surface motion. Time-reversal based techniques offer a low complexity solution to decrease interferences caused by multipath, but a complete equalization cannot be reached (it saturates when maximize signal to noise ratio and these techniques in conventional form are quite sensible to channel variations along the transmission. Acoustic propagation modeling in high frequency regime can yield physical-based information that is potentially useful to channel compensation methods as the passive time-reversal (pTR, which is often employed in Digital Acoustic Underwater Communications (DAUC systems because of its low computational cost. Aiming to overcome the difficulties of pTR to solve time-variations in underwater channels, it is intended to insert physical knowledge from acoustic propagation modeling in the pTR filtering. Investigation is being done by the authors about the influence of channel physical parameters on propagation of coherent acoustic signals transmitted through shallow water waveguides and received in a vertical line array of sensors. Time-variant approach is used, as required to model high frequency acoustic propagation on realistic scenarios, and applied to a DAUC simulator containing an adaptive passive time-reversal receiver (ApTR. The understanding about the effects of changes in physical features of the channel over the propagation can lead to design ApTR filters which could help to improve the communications system performance. This work presents a short extension and review of the paper 12, which tested Doppler distortion induced by source-surface motion and ApTR compensation for a DAUC system on a simulated time-variant channel, in the scope of model-based equalization. Environmental focusing approach

  8. Planck-scale physics and solutions to the strong CP-problem without axion

    International Nuclear Information System (INIS)

    Berezhiani, Z.G.; Mohapatra, R.N.; Senjanovic, G.

    1992-12-01

    We analyse the impact of quantum gravity on the possible solutions to the strong CP problem which utilize the spontaneously broken discrete symmetries, such as parity and time reversal invariance. We find that the stability of the solution under Planck scale effects provides an upper limit on the scale Λ of relevant symmetry breaking. This result is mode dependent and the bound is most restrictive for the seesaw type models of fermion masses, with Λ 6 GeV. (author). 32 refs

  9. Experimental study of time-reversal invariance in neutron-nucleus interactions

    International Nuclear Information System (INIS)

    Shaparov, E.I.; Shimizu, H.M.

    1996-01-01

    Experimental approaches for the test of time-reversal invariance in neutron-nucleus interactions are reviewed. Possible transmission experiments with polarized neutron beams and polarized or aligned targets are discussed as well as neutron capture experiments with unpolarized resonance neutrons. 102 refs., 13 figs., 3 tabs

  10. Noncommutative gauge theory and symmetry breaking in matrix models

    International Nuclear Information System (INIS)

    Grosse, Harald; Steinacker, Harold; Lizzi, Fedele

    2010-01-01

    We show how the fields and particles of the standard model can be naturally realized in noncommutative gauge theory. Starting with a Yang-Mills matrix model in more than four dimensions, an SU(n) gauge theory on a Moyal-Weyl space arises with all matter and fields in the adjoint of the gauge group. We show how this gauge symmetry can be broken spontaneously down to SU(3) c xSU(2) L xU(1) Q [resp. SU(3) c xU(1) Q ], which couples appropriately to all fields in the standard model. An additional U(1) B gauge group arises which is anomalous at low energies, while the trace-U(1) sector is understood in terms of emergent gravity. A number of additional fields arise, which we assume to be massive, in a pattern that is reminiscent of supersymmetry. The symmetry breaking might arise via spontaneously generated fuzzy spheres, in which case the mechanism is similar to brane constructions in string theory.

  11. Kink-induced symmetry breaking patterns in brane-world SU(3)3 trinification models

    International Nuclear Information System (INIS)

    Demaria, Alison; Volkas, Raymond R.

    2005-01-01

    The trinification grand unified theory (GUT) has gauge group SU(3) 3 and a discrete symmetry permuting the SU(3) factors. In common with other GUTs, the attractive nature of the fermionic multiplet assignments is obviated by the complicated multiparameter Higgs potential apparently needed for phenomenological reasons, and also by vacuum expectation value (VEV) hierarchies within a given multiplet. This motivates the rigorous consideration of Higgs potentials, symmetry breaking patterns, and alternative symmetry breaking mechanisms in models with this gauge group. Specifically, we study the recently proposed 'clash of symmetries' brane-world mechanism to see if it can help with the symmetry breaking conundrum. This requires a detailed analysis of Higgs potential global minima and kink or domain wall solutions interpolating between the disconnected global minima created through spontaneous discrete symmetry breaking. Sufficiently long-lived metastable kinks can also be considered. We develop what we think is an interesting, albeit speculative, brane-world scheme whereby the hierarchical symmetry breaking cascade, trinification to left-right symmetry to the standard model to color cross electromagnetism, may be induced without an initial hierarchy in vacuum expectation values. Another motivation for this paper is simply to continue the exploration of the rich class of kinks arising in models that are invariant under both discrete and continuous symmetries

  12. Research on Spontaneously Emerged Chromosomal Aberrations in the Periphery Blood Lymphocytes in Cattle (‘Buša’ Breed

    Directory of Open Access Journals (Sweden)

    Danica Hasanbašić

    2007-11-01

    Full Text Available Knowledge of spontaneous aberrations, namely, of their frequency in non-irradiated cells is of paramount importance not only in cytogenetic research, but also in contemporary animal production.The paper deals with research on spontaneously emerged chromosomal aberrations in the peripheral blood lymphocytes in the cattle of ‘Buša’ breed.To obtain metaphase chromosomes the conventional method of lymphocyte cultivation was used, albeit slightly modified and adapted to the examined animals and the laboratory conditions.The research findings indicate that a certain percent of spontaneously emerged chromosomal aberrations of chromatid type (gap and break have been found in the peripheral blood lymphocytes in the cattle of ‘Buša’ breed.

  13. The Break

    DEFF Research Database (Denmark)

    Strand, Anete Mikkala Camille

    2018-01-01

    storytelling to enact fruitful breakings of patterns unbecoming. The claim being, that the hamster wheel of Work-life anno 2016 needs reconfiguration and the simple yet fruitful manner by which this is done is through acknowledging the benefits of bodies, spaces and artifacts – and the benefits of actually...... taking a break, discontinuing for a moment in order to continue better, wiser and more at ease. Both within and as part of the daily routines, and – now and then – outside these routines in the majesty of nature with time to explore and redirect the course of life in companionships with fellow man...

  14. The Organization of Behavior Over Time: Insights from Mid-Session Reversal.

    Science.gov (United States)

    Rayburn-Reeves, Rebecca M; Cook, Robert G

    2016-01-01

    What are the mechanisms by which behavior is organized sequentially over time? The recently developed mid-session reversal (MSR) task offers new insights into this fundamental question. The typical MSR task is arranged to have a single reversed discrimination occurring in a consistent location within each session and across sessions. In this task, we examine the relevance of time, reinforcement, and other factors as the switching cue in the sequential modulation of control in MSR. New analyses also highlight some of the potential mechanisms underlying this serially organized behavior. MSR provides new evidence and we offer some ideas about how cues interact to compete for the control of behavior within and across sessions. We suggest that MSR is an excellent preparation for studying the competition among psychological states and their resolution toward action.

  15. Testing the causality of Hawkes processes with time reversal

    Science.gov (United States)

    Cordi, Marcus; Challet, Damien; Muni Toke, Ioane

    2018-03-01

    We show that univariate and symmetric multivariate Hawkes processes are only weakly causal: the true log-likelihoods of real and reversed event time vectors are almost equal, thus parameter estimation via maximum likelihood only weakly depends on the direction of the arrow of time. In ideal (synthetic) conditions, tests of goodness of parametric fit unambiguously reject backward event times, which implies that inferring kernels from time-symmetric quantities, such as the autocovariance of the event rate, only rarely produce statistically significant fits. Finally, we find that fitting financial data with many-parameter kernels may yield significant fits for both arrows of time for the same event time vector, sometimes favouring the backward time direction. This goes to show that a significant fit of Hawkes processes to real data with flexible kernels does not imply a definite arrow of time unless one tests it.

  16. Time reversal for ultrasonic transcranial surgery and echographic imaging

    Science.gov (United States)

    Tanter, Mickael; Aubry, Jean-Francois; Vignon, Francois; Fink, Mathias

    2005-09-01

    High-intensity focused ultrasound (HIFU) is able to induce non-invasively controlled and selective destruction of tissues by focusing ultrasonic beams within organs, analogous to a magnifying glass that concentrates enough sunlight to burn a hole in paper. The brain is an attractive organ in which to perform ultrasonic tissue ablation, but such an application has been hampered by the strong defocusing effect of the skull bone. Our group has been involved in this topic for several years, providing proofs of concept and proposing technological solutions to this problem. Thanks to a high-power time-reversal mirror, presented here are in vivo thermal lesions induced through the skull of 12 sheep. Thermal lesions were confirmed by T2-weighted magnetic resonance post-treatment images and histological examination. These results provide striking evidence that noninvasive ultrasound brain surgery is feasible. A recent approach for high-resolution brain ultrasonic imaging will also be discussed with a skull aberration correction technique based on twin arrays technology. The correction of transcranial ultrasonic images is implemented on a new generation of time-reversal mirrors relying on a fully programmable transmit and receive beamformer.

  17. Time reversal invariance - a test in free neutron decay

    Energy Technology Data Exchange (ETDEWEB)

    Lising, Laura Jean [Univ. of California, Berkeley, CA (United States)

    1999-01-01

    Time reversal invariance violation plays only a small role in the Standard Model, and the existence of a T-violating effect above the predicted level would be an indication of new physics. A sensitive probe of this symmetry in the weak interaction is the measurement of the T-violating ''D''-correlation in the decay of free neutrons. The triple-correlation Dσn∙pe x pv involves three kinematic variables, the neutron spin, electron momentu, and neutrino (or proton) momentum, and changes sign under time reversal. This experiment detects the decay products of a polarized cold neutron beam with an octagonal array of scintillation and solid-state detectors. Data from first run at NIST's Cold Neutron Research Facility give a D-coefficient of -0.1 ± 1.3(stat.) ± 0.7(syst) x 10-3 This measurement has the greatest bearing on extensions to the Standard model that incorporate leptoquarks, although exotic fermion and lift-right symmetric models also allow a D as large as the present limit.

  18. Transmission mode acoustic time-reversal imaging for nondestructive evaluation

    Science.gov (United States)

    Lehman, Sean K.; Devaney, Anthony J.

    2002-11-01

    In previous ASA meetings and JASA papers, the extended and formalized theory of transmission mode time reversal in which the transceivers are noncoincident was presented. When combined with the subspace concepts of a generalized MUltiple SIgnal Classification (MUSIC) algorithm, this theory is used to form super-resolution images of scatterers buried in a medium. These techniques are now applied to ultrasonic nondestructive evaluation (NDE) of parts, and shallow subsurface seismic imaging. Results are presented of NDE experiments on metal and epoxy blocks using data collected from an adaptive ultrasonic array, that is, a ''time-reversal machine,'' at Lawrence Livermore National Laboratory. Also presented are the results of seismo-acoustic subsurface probing of buried hazardous waste pits at the Idaho National Engineering and Environmental Laboratory. [Work performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.] [Work supported in part by CenSSIS, the Center for Subsurface Sensing and Imaging Systems, under the Engineering Research Centers Program of the NSF (award number EEC-9986821) as well as from Air Force Contracts No. F41624-99-D6002 and No. F49620-99-C0013.

  19. On-off intermittency in time series of spontaneous paroxysmal activity in rats with genetic absence epilepsy

    International Nuclear Information System (INIS)

    Hramov, Alexander; Koronovskii, Alexey A.; Midzyanovskaya, I.S.; Sitnikova, E.; Rijn, C.M. van

    2006-01-01

    In the present paper we consider the on-off intermittency phenomena observed in time series of spontaneous paroxysmal activity in rats with genetic absence epilepsy. The method to register and analyze the electroencephalogram with the help of continuous wavelet transform is also suggested

  20. Investigations of chiral symmetry breaking and topological aspects of lattice QCD

    International Nuclear Information System (INIS)

    Garcia Ramos, Elena

    2013-01-01

    The spontaneous breaking of chiral symmetry is a fascinating phenomenon of QCD whose mechanism is still not well understood and it has fundamental phenomenological implications. It is, for instance, responsible for the low mass of the pions which are effectively Goldstone bosons of the spontaneously broken symmetry. Since these phenomena belong to the low energy regime of QCD, non-perturbative techniques have to be applied in order to study them. In this work we use the twisted mass lattice QCD regularization to compute the chiral condensate, the order parameter of spontaneous chiral symmetry breaking. To this end we apply the recently introduced method of spectral projectors which allows us to perform calculations in large volumes due to its inherently low computational cost. This approach, moreover, enables a direct calculation of the chiral condensate based on a theoretically clean definition of the observable via density chains. We thus present a continuum limit determination of the chirally extrapolated condensate for N f =2 and N f =2+1+1 flavours of twisted mass fermions at maximal twist. In addition we study the chiral behavior of the topological susceptibility, a measure of the topological fluctuations of the gauge fields. We again apply the spectral projector method for this calculation. We comment on the difficulties which appear in the calculation of this observable due to the large autocorrelations involved. Finally we present the continuum limit result of the topological susceptibility in the pure gluonic theory which allows us to perform a test of the Witten-Veneziano relation. We found that this relation is well satisfied. Our results support the validity of the Witten-Veneziano formula which relates the topological fluctuations of the gauge fields with the unexpectedly large value of the η' mass.

  1. Topological defect formation and spontaneous symmetry breaking in ion Coulomb crystals.

    Science.gov (United States)

    Pyka, K; Keller, J; Partner, H L; Nigmatullin, R; Burgermeister, T; Meier, D M; Kuhlmann, K; Retzker, A; Plenio, M B; Zurek, W H; del Campo, A; Mehlstäubler, T E

    2013-01-01

    Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry state independently. Where such local choices are incompatible, topological defects can form. The Kibble-Zurek mechanism predicts the defect densities to follow a power law that scales with the rate of the transition. Owing to its ubiquitous nature, this theory finds application in a wide field of systems ranging from cosmology to condensed matter. Here we present the successful creation of defects in ion Coulomb crystals by a controlled quench of the confining potential, and observe an enhanced power law scaling in accordance with numerical simulations and recent predictions. This simple system with well-defined critical exponents opens up ways to investigate the physics of non-equilibrium dynamics from the classical to the quantum regime.

  2. A Baseline-Free Defect Imaging Technique in Plates Using Time Reversal of Lamb Waves

    International Nuclear Information System (INIS)

    Jeong, Hyunjo; Cho, Sungjong; Wei, Wei

    2011-01-01

    We present an analytical investigation for a baseline-free imaging of a defect in plate-like structures using the time-reversal of Lamb waves. We first consider the flexural wave (A 0 mode) propagation in a plate containing a defect, and reception and time reversal process of the output signal at the receiver. The received output signal is then composed of two parts: a directly propagated wave and a scattered wave from the defect. The time reversal of these waves recovers the original input signal, and produces two additional sidebands that contain the time-of-flight information on the defect location. One of the side-band signals is then extracted as a pure defect signal. A defect localization image is then constructed from a beamforming technique based on the time-frequency analysis of the side band signal for each transducer pair in a network of sensors. The simulation results show that the proposed scheme enables the accurate, baseline-free imaging of a defect. (fundamental areas of phenomenology(including applications))

  3. Push back to respond better: regulatory inhibition of the DNA double-strand break response.

    Science.gov (United States)

    Panier, Stephanie; Durocher, Daniel

    2013-10-01

    Single DNA lesions such as DNA double-strand breaks (DSBs) can cause cell death or trigger genome rearrangements that have oncogenic potential, and so the pathways that mend and signal DNA damage must be highly sensitive but, at the same time, selective and reversible. When initiated, boundaries must be set to restrict the DSB response to the site of the lesion. The integration of positive and, crucially, negative control points involving post-translational modifications such as phosphorylation, ubiquitylation and acetylation is key for building fast, effective responses to DNA damage and for mitigating the impact of DNA lesions on genome integrity.

  4. On van der Waals-like forces in spontaneously broken supersymmetries

    International Nuclear Information System (INIS)

    Radescu, E.E.

    1982-12-01

    In spontaneously broken rigid supersymmetry, Goldstone fermion pair exchange should lead to a universal interaction between massive bodies uniquely fixed by the existing low energy theorem. The resulting van der Waals-like potential is shown to be V(r)=Mmπ -3 F -4 r -7 +O(r -8 ), where M,m are the masses of the interacting bodies while √F is the scale of the breaking. The change in the situation when the supersymmetry is promoted to a local one is briefly discussed. (author)

  5. Climate and floods still govern California levee breaks

    Science.gov (United States)

    Florsheim, J.L.; Dettinger, M.D.

    2007-01-01

    Even in heavily engineered river systems, climate still governs flood variability and thus still drives many levee breaks and geomorphic changes. We assemble a 155-year record of levee breaks for a major California river system to find that breaks occurred in 25% of years during the 20th Century. A relation between levee breaks and river discharge is present that sets a discharge threshold above which most levee breaks occurred. That threshold corresponds to small floods with recurrence intervals of ???2-3 years. Statistical analysis illustrates that levee breaks and peak discharges cycle (broadly) on a 12-15 year time scale, in time with warm-wet storm patterns in California, but more slowly or more quickly than ENSO and PDO climate phenomena, respectively. Notably, these variations and thresholds persist through the 20th Century, suggesting that historical flood-control effects have not reduced the occurrence or frequency of levee breaks. Copyright 2007 by the American Geophysical Union.

  6. Give Young Scientists a Break

    Energy Technology Data Exchange (ETDEWEB)

    Wiley, H. S.

    2009-11-01

    There has been much concern about the impact of tight funding on the careers of young scientists. When only a small percentage of grants are approved, even the smallest problem or error with an application can push it out of the funding range. Unfortunately, the relative lack of grant writing skills by new investigators often has this effect. To avoid a situation where only experienced investigators with polished writing skills are funded, the National Institutes of Health has instituted a more generous ranking scale for new investigators. Not surprisingly, some senior investigators have protested, calling it reverse discrimination. I say that their anger is misplaced. New investigators do deserve a break.

  7. Time asymmetries in quantum cosmology and the search for boundary conditions to the Wheeler-DeWitt equation

    Energy Technology Data Exchange (ETDEWEB)

    Castagnino, Mario [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Catren, Gabriel [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Ferraro, Rafael [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina)

    2002-09-21

    This paper addresses the quantization of minisuperspace cosmological models by studying a possible solution to the problem of time and time asymmetries in quantum cosmology. Since general relativity does not have a privileged time variable of Newtonian type, it is necessary, in order to have a dynamical evolution, to select a physical clock. This choice yields, in the proposed approach, to the breaking of the so-called clock-reversal invariance of the theory which is clearly distinguished from the well-known motion-reversal invariance of both classical and quantum mechanics. In light of this new perspective, the problem of imposing proper boundary conditions on the space of solutions of the Wheeler-DeWitt equation is reformulated. The symmetry-breaking formalism of previous papers is analyzed and a clarification of it is proposed in order to satisfy the requirements of the new interpretation.

  8. Time asymmetries in quantum cosmology and the search for boundary conditions to the Wheeler-DeWitt equation

    International Nuclear Information System (INIS)

    Castagnino, Mario; Catren, Gabriel; Ferraro, Rafael

    2002-01-01

    This paper addresses the quantization of minisuperspace cosmological models by studying a possible solution to the problem of time and time asymmetries in quantum cosmology. Since general relativity does not have a privileged time variable of Newtonian type, it is necessary, in order to have a dynamical evolution, to select a physical clock. This choice yields, in the proposed approach, to the breaking of the so-called clock-reversal invariance of the theory which is clearly distinguished from the well-known motion-reversal invariance of both classical and quantum mechanics. In light of this new perspective, the problem of imposing proper boundary conditions on the space of solutions of the Wheeler-DeWitt equation is reformulated. The symmetry-breaking formalism of previous papers is analyzed and a clarification of it is proposed in order to satisfy the requirements of the new interpretation

  9. Hydrodynamic interaction induced spontaneous rotation of coupled active filaments.

    Science.gov (United States)

    Jiang, Huijun; Hou, Zhonghuai

    2014-12-14

    We investigate the coupled dynamics of active filaments with long range hydrodynamic interactions (HI). Remarkably, we find that filaments can rotate spontaneously under the same conditions in which a single filament alone can only move in translation. Detailed analysis reveals that the emergence of coupled rotation originates from an asymmetric flow field associated with HI which breaks the symmetry of translational motion when filaments approach. The breaking is then further stabilized by HI to form self-sustained coupled rotation. Intensive simulations show that coupled rotation forms easily when one filament tends to collide with the front-half of the other. For head-to-tail approaching, we observe another interesting HI-induced coupled motion, where filaments move together in the form of one following the other. Moreover, the radius of coupled rotation increases exponentially as the rigidity of the filament increases, which suggests that HI are also important for the alignment of rigid-rod-like filaments which has been assumed to be solely a consequence of direct collisions.

  10. Sparse least-squares reverse time migration using seislets

    KAUST Repository

    Dutta, Gaurav

    2015-08-19

    We propose sparse least-squares reverse time migration (LSRTM) using seislets as a basis for the reflectivity distribution. This basis is used along with a dip-constrained preconditioner that emphasizes image updates only along prominent dips during the iterations. These dips can be estimated from the standard migration image or from the gradient using plane-wave destruction filters or structural tensors. Numerical tests on synthetic datasets demonstrate the benefits of this method for mitigation of aliasing artifacts and crosstalk noise in multisource least-squares migration.

  11. Robust and Reversible Audio Watermarking by Modifying Statistical Features in Time Domain

    Directory of Open Access Journals (Sweden)

    Shijun Xiang

    2017-01-01

    Full Text Available Robust and reversible watermarking is a potential technique in many sensitive applications, such as lossless audio or medical image systems. This paper presents a novel robust reversible audio watermarking method by modifying the statistic features in time domain in the way that the histogram of these statistical values is shifted for data hiding. Firstly, the original audio is divided into nonoverlapped equal-sized frames. In each frame, the use of three samples as a group generates a prediction error and a statistical feature value is calculated as the sum of all the prediction errors in the frame. The watermark bits are embedded into the frames by shifting the histogram of the statistical features. The watermark is reversible and robust to common signal processing operations. Experimental results have shown that the proposed method not only is reversible but also achieves satisfactory robustness to MP3 compression of 64 kbps and additive Gaussian noise of 35 dB.

  12. Spontaneous symmetry breaking as a basis of particle mass

    International Nuclear Information System (INIS)

    Quigg, Chris

    2007-01-01

    Electroweak theory joins electromagnetism with the weak force in a single quantum field theory, ascribing the two fundamental interactions-so different in their manifestations-to a common symmetry principle. How the electroweak gauge symmetry is hidden is one of the most urgent and challenging questions facing particle physics. The provisional answer incorporated in the 'standard model' of particle physics was formulated in the 1960s by Higgs, by Brout and Englert and by Guralnik, Hagen, and Kibble: the agent of electroweak symmetry breaking is an elementary scalar field whose self-interactions select a vacuum state in which the full electroweak symmetry is hidden, leaving a residual phase symmetry of electromagnetism. By analogy with the Meissner effect of the superconducting phase transition, the Higgs mechanism, as it is commonly known, confers masses on the weak force carriers W ± and Z. It also opens the door to masses for the quarks and leptons, and shapes the world around us. It is a good story-though an incomplete story-and we do not know how much of the story is true. Experiments that explore the Fermi scale (the energy regime around 1 TeV) during the next decade will put the electroweak theory to decisive test, and may uncover new elements needed to construct a more satisfying completion of the electroweak theory. The aim of this article is to set the stage by reporting what we know and what we need to know, and to set some 'big questions' that will guide our explorations

  13. Spontaneous Symmetry Breaking as a Basis of Particle Mass

    International Nuclear Information System (INIS)

    Quigg, Chris

    2007-01-01

    Electroweak theory joins electromagnetism with the weak force in a single quantum field theory, ascribing the two fundamental interactions--so different in their manifestations--to a common symmetry principle. How the electroweak gauge symmetry is hidden is one of the most urgent and challenging questions facing particle physics. The provisional answer incorporated in the ''standard model'' of particle physics was formulated in the 1960s by Higgs, by Brout and Englert, and by Guralnik, Hagen, and Kibble: The agent of electroweak symmetry breaking is an elementary scalar field whose self-interactions select a vacuum state in which the full electroweak symmetry is hidden, leaving a residual phase symmetry of electromagnetism. By analogy with the Meissner effect of the superconducting phase transition, the Higgs mechanism, as it is commonly known, confers masses on the weak force carriers W ± and Z. It also opens the door to masses for the quarks and leptons, and shapes the world around us. It is a good story--though an incomplete story--and we do not know how much of the story is true. Experiments that explore the Fermi scale (the energy regime around 1 TeV) during the next decade will put the electroweak theory to decisive test, and may uncover new elements needed to construct a more satisfying completion of the electroweak theory. The aim of this article is to set the stage by reporting what we know and what we need to know, and to set some ''Big Questions'' that will guide our explorations

  14. Spontaneous Symmetry Breaking as a Basis of Particle Mass

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab /CERN

    2007-04-01

    Electroweak theory joins electromagnetism with the weak force in a single quantum field theory, ascribing the two fundamental interactions--so different in their manifestations--to a common symmetry principle. How the electroweak gauge symmetry is hidden is one of the most urgent and challenging questions facing particle physics. The provisional answer incorporated in the ''standard model'' of particle physics was formulated in the 1960s by Higgs, by Brout & Englert, and by Guralnik, Hagen, & Kibble: The agent of electroweak symmetry breaking is an elementary scalar field whose self-interactions select a vacuum state in which the full electroweak symmetry is hidden, leaving a residual phase symmetry of electromagnetism. By analogy with the Meissner effect of the superconducting phase transition, the Higgs mechanism, as it is commonly known, confers masses on the weak force carriers W{sup {+-}} and Z. It also opens the door to masses for the quarks and leptons, and shapes the world around us. It is a good story--though an incomplete story--and we do not know how much of the story is true. Experiments that explore the Fermi scale (the energy regime around 1 TeV) during the next decade will put the electroweak theory to decisive test, and may uncover new elements needed to construct a more satisfying completion of the electroweak theory. The aim of this article is to set the stage by reporting what we know and what we need to know, and to set some ''Big Questions'' that will guide our explorations.

  15. A time reversal transmission approach for multi-user UWB communications

    DEFF Research Database (Denmark)

    Nguyen, Tuan Hung; Kovacs Z., Istvan; Eggers, Patrick

    2005-01-01

    In this paper we propose and evaluate the performance of the time reversal technique in impulse radio UWB communications. The evaluation was based on measured channel impulse responses in the UWB frequency band of 3 to 5 GHz of a 4x1 MISO system with both vertical and horizontal polarization at t...

  16. New results for time reversed symplectic dynamic systems and quadratic functionals

    Directory of Open Access Journals (Sweden)

    Roman Simon Hilscher

    2012-05-01

    Full Text Available In this paper, we examine time scale symplectic (or Hamiltonian systems and the associated quadratic functionals which contain a forward shift in the time variable. Such systems and functionals have a close connection to Jacobi systems for calculus of variations and optimal control problems on time scales. Our results, among which we consider the Reid roundabout theorem, generalize the corresponding classical theory for time reversed discrete symplectic systems, as well as they complete the recently developed theory of time scale symplectic systems.

  17. Two applications of time reversal mirrors: Seismic radio and seismic radar

    KAUST Repository

    Hanafy, Sherif M.; Schuster, Gerard T.

    2011-01-01

    Two seismic applications of time reversal mirrors (TRMs) are introduced and tested with field experiments. The first one is sending, receiving, and decoding coded messages similar to a radio except seismic waves are used. The second one is, similar

  18. QUANTITATION OF INTRACELLULAR NAD(P)H IN LIVING CELLS CAN MONITOR AN IMBALANCE OF DNA SINGLE STRAND BREAK REPAIR IN REAL TIME

    Science.gov (United States)

    Quantitation of intracellular NAD(P)H in living cells can monitor an imbalance of DNA single strand break repair in real time.ABSTRACTDNA single strand breaks (SSBs) are one of the most frequent DNA lesions in genomic DNA generated either by oxidative stress or du...

  19. Do children report differently from their parents and from observed data? Cross-sectional data on fruit, water, sugar-sweetened beverages and break-time foods.

    Science.gov (United States)

    van de Gaar, V M; Jansen, W; van der Kleij, M J J; Raat, H

    2016-04-18

    Reliable assessment of children's dietary behaviour is needed for research purposes. The aim of this study was (1) to investigate the level of agreement between observed and child-reported break-time food items; and (2) to investigate the level of agreement between children's reports and those of their parents regarding children's overall consumption of fruit, water and sugar-sweetened beverages (SSB). The children in this study were 9-13 years old, attending primary schools in Rotterdam, the Netherlands. Children were observed with respect to foods brought for break-time at school. At the same day, children completed a questionnaire in which they were asked to recall the food(s) they brought to school to consume during break-time. Only paired data (observed and child-reported) were included in the analyses (n = 407 pairs). To determine each child's daily consumption and average amounts of fruit, water and SSB consumed, children and their parents completed parallel questionnaires. Only paired data (parent-reported and child-reported) were included in the analyses (n = 275 pairs). The main statistical measures were level of agreement between break-time foods, fruit, water and SSB; and Intra-class Correlation Coefficients (ICC). More children reported bringing sandwiches and snacks for break-time than was observed (73 % vs 51 % observed and 84 % vs 33 % observed). The overall agreement between observed and child-reported break-time foods was poor to fair, with ICC range 0.16-0.39 (p Children reported higher average amounts of SSB consumed than did their parents (1.3 vs 0.9 L SSB, p parent estimations of the child's water and fruit consumption were similar. ICC between parent and child reports was poor to good (range 0.22-0.62, p Children report higher on amount of break-time foods as compared to observations and children's reports of SSB consumption are higher than those of their parents. Since the level of agreement between the observed break-time

  20. Spontaneous symmetry breaking and neutral stability in the noncanonical Hamiltonian formalism

    International Nuclear Information System (INIS)

    Morrison, P.J.; Eliezer, S.

    1985-10-01

    The noncanonical Hamiltonian formalism is based upon a generalization of the Poisson bracket, a particular form of which is possessed by continuous media fields. Associated with this generalization are special constants of motion called Casimirs. These are constants that can be viewed as being built into the phase space, for they are invariant for all Hamiltonians. Casimirs are important because when added to the Hamiltonian they yield an effective Hamiltonian that produces equilibrium states upon variation. The stability of these states can be ascertained by a second variation. Goldstone's theorem, in its usual context, determines zero eigenvalues of the mass matrix for a given vacuum state, the equilibrium with minimum energy. Here, since for fluids and plasmas the vacuum state is uninteresting, we examine symmetry breaking for general equilibria. Broken symmetries imply directions of neutral stability. Two examples are presented: the nonlinear Alfven wave of plasma physics and the Korteweg-de Vries soliton. 46 refs

  1. Subjective figure reversal in two- and three-dimensional perceptual space.

    Science.gov (United States)

    Radilová, J; Radil-Weiss, T

    1984-08-01

    A permanently illuminated pattern of Mach's truncated pyramid can be perceived according to the experimental instruction given, either as a three-dimensional reversible figure with spontaneously changing convex and concave interpretation (in one experiment), or as a two-dimensional reversible figure-ground pattern (in another experiment). The reversal rate was about twice as slow, without the subjects being aware of it, if it was perceived as a three-dimensional figure compared to the situation when it was perceived as two-dimensional. It may be hypothetized that in the three-dimensional case, the process of perception requires more sequential steps than in the two-dimensional one.

  2. When does taking a break help in negotiations? The influence of breaks and social motivation on negotiation processes and outcomes

    NARCIS (Netherlands)

    Harinck, F.; de Dreu, C.K.W.

    2011-01-01

    Most negotiations are interrupted from time to time to reflect on the negotiation or to do other pressing tasks. This study investigated how these breaks and the thoughts during these breaks influence subsequent negotiation behavior. Prosocially motivated dyads, with a tendency to think

  3. Higgs as a pseudo-Goldstone boson, the mu problem and gauge-mediated supersymmetry breaking

    International Nuclear Information System (INIS)

    Kaminska, Anna; Lavignac, Stephane

    2011-01-01

    We study the interplay between the spontaneous breaking of a global symmetry of the Higgs sector and gauge-mediated supersymmetry breaking, in the framework of a supersymmetric model with global SU(3) symmetry. In addition to solving the supersymmetric flavor problem and alleviating the little hierarchy problem, this scenario automatically triggers the breaking of the global symmetry and provides an elegant solution to the μ/Bμ problem of gauge mediation. We study in detail the processes of global symmetry and electroweak symmetry breaking, including the contributions of the top/stop and gauge-Higgs sectors to the one-loop effective potential of the pseudo-Goldstone Higgs boson. While the joint effect of supersymmetry and of the global symmetry allows in principle the electroweak symmetry to be broken with little fine-tuning, the simplest version of the model fails to bring the Higgs mass above the LEP bound due to a suppressed tree-level quartic coupling. To cure this problem, we consider the possibility of additional SU(3)-breaking contributions to the Higgs potential, which results in a moderate fine-tuning. The model predicts a rather low messenger scale, a small tan β value, a light Higgs boson with Standard Model-like properties, and heavy higgsinos. (orig.)

  4. Supersymmetry breaking from superstrings

    International Nuclear Information System (INIS)

    Gaillard, M.K.

    1990-05-01

    The gauge hierarchy problem is briefly reviewed and a class of effective field theories obtained from superstrings is described. These are characterized by a classical symmetry, related to the space-time duality of string theory, that is responsible for the suppression of observable supersymmetry breaking effects. At the quantum level, the symmetry is broken by anomalies that provide the seed of observable supersymmetry breaking, and an acceptably large gauge hierarchy may be generated. 26 refs

  5. Supersymmetry breaking from superstrings

    International Nuclear Information System (INIS)

    Gaillard, M.K.; Lawrence Berkeley Lab., CA; California Univ., Berkeley

    1990-01-01

    The gauge hierarchy problem is briefly reviewed and a class of effective field theories obtained from superstrings is described. These are characterized by a clasical symmetry, related to the space-time duality of string theory, that is responsible for the suppression of observable supersymmetry breaking effects. At the quantum level, the symmetry is broken by anomalies that provide the seed of observable supersymmetry breaking, and an acceptably large gauge hierarchy may be generated

  6. Reverse time migration of multiples for OBS data

    KAUST Repository

    Zhang, Dongliang

    2014-01-01

    Reverse time migration of multiples (RTMM) is applied to OBS data with sparse receiver spacing. RTMM for OBS data unlike a marine streamer acquisition is implemented in the common receiver gathers (CRG) and provides a wider and denser illumination for each CRG than the conventional RTM of primaries. Hence, while the the conventional RTM image contains strong aliasing artifacts due to a sparser receiver interval, the RTMM image suffers from this artifacts less. This benefit of RTMM is demonstrated with numerical test on the Marmousi model for sparsely sampled OBS data.

  7. Reverse time migration of multiples for OBS data

    KAUST Repository

    Zhang, Dongliang

    2014-08-05

    Reverse time migration of multiples (RTMM) is applied to OBS data with sparse receiver spacing. RTMM for OBS data unlike a marine streamer acquisition is implemented in the common receiver gathers (CRG) and provides a wider and denser illumination for each CRG than the conventional RTM of primaries. Hence, while the the conventional RTM image contains strong aliasing artifacts due to a sparser receiver interval, the RTMM image suffers from this artifacts less. This benefit of RTMM is demonstrated with numerical test on the Marmousi model for sparsely sampled OBS data.

  8. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2011-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  9. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  10. On the record process of time-reversible spectrally-negative Markov additive processes

    NARCIS (Netherlands)

    J. Ivanovs; M.R.H. Mandjes (Michel)

    2009-01-01

    htmlabstractWe study the record process of a spectrally-negative Markov additive process (MAP). Assuming time-reversibility, a number of key quantities can be given explicitly. It is shown how these key quantities can be used when analyzing the distribution of the all-time maximum attained by MAPs

  11. Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

    International Nuclear Information System (INIS)

    Hedqvist, A.; Rachlew-Kaellne, E.

    1998-01-01

    Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and Z eff together with a description of the interpretation and the equipment are presented. (author)

  12. Effect of Time and Burial Depth on Breaking Seed dormancy and Germination of Weed Seeds

    Directory of Open Access Journals (Sweden)

    marzie mazhari

    2016-02-01

    order to evaluate the effects of time and burial depth on breaking seed dormancy and percentage of germination of 27 dominants weed in Shahrekord region, an experiment was conducted at the research field at Shahrekord University in 2013. The experimental design set as factorial based on completely randomized design with three replications. Treatments consisted of three burial time levels (1, 2 and 3 months and 4 burial depth (0, 5, 15 and 25 cm from surface soil layer after 1, 2 and 3 months of burial. Results and Discussion: Results showed that the time and the depth of burial treatments had significant effect on breaking seed dormancy and germination percentage. Seeds retrieved from the soil surface showed highest dormancy percentage and breaking dormancy with increasing the depth and time of seed burial. The results showed that the effects of three burial times, burial depth and interaction of burial time and burial depth had significant effects on dormancy breaking and germination of weed seeds. The bitter herbs of expression and parsnip, the highest percentage of seed dormancy breaking. Germination of Geobelia alopecuoides and Anthriscus sylvestris was observed from seed burial depth of 15 cm. However, the germination percentage, between two and three seed burial months, did not show any significant difference. In this study, Convolvulus arvensies, Rumex acetisella and, Avena fatua in the highest depth (25 cm had the maximum seed germination. Tillage would bury weed seeds and may help to preserve some seeds, because the seeds on the soil surface or near it, are prone to hunting or decay that eventually, their number is reduced in the soil seed bank. Weed seeds of Centurea cyanus, Geobelia alopecuoides, Turgeniala tifolia, Tragopogon collinus, Bromus dantoniae and Anthriscus sylvestris had more germination percentage with increasing depth to 15 cm, but beyond this depth due to the negative impacts of increased depth, seed germination declined sharply. In fact, the

  13. Associations of Sedentary Behavior, Sedentary Bouts and Breaks in Sedentary Time with Cardiometabolic Risk in Children with a Family History of Obesity

    OpenAIRE

    Saunders, Travis John; Tremblay, Mark Stephen; Mathieu, Marie-?ve; Henderson, M?lanie; O?Loughlin, Jennifer; Tremblay, Angelo; Chaput, Jean-Philippe

    2013-01-01

    Background Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children. Purpose To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8?11 years with a family history of obesity. Methods Data from 286 boys and 236 girls living in Quebec, Cana...

  14. Unification of SUSY breaking and GUT breaking

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Tatsuo [Department of Physics, Hokkaido University,Sapporo 060-0810 (Japan); Omura, Yuji [Department of Physics, Nagoya University,Nagoya 464-8602 (Japan)

    2015-02-18

    We build explicit supersymmetric unification models where grand unified gauge symmetry breaking and supersymmetry (SUSY) breaking are caused by the same sector. Besides, the SM-charged particles are also predicted by the symmetry breaking sector, and they give the soft SUSY breaking terms through the so-called gauge mediation. We investigate the mass spectrums in an explicit model with SU(5) and additional gauge groups, and discuss its phenomenological aspects. Especially, nonzero A-term and B-term are generated at one-loop level according to the mediation via the vector superfields, so that the electro-weak symmetry breaking and 125 GeV Higgs mass may be achieved by the large B-term and A-term even if the stop mass is around 1 TeV.

  15. Reversible infantile mitochondrial diseases.

    Science.gov (United States)

    Boczonadi, Veronika; Bansagi, Boglarka; Horvath, Rita

    2015-05-01

    Mitochondrial diseases are usually severe and progressive conditions; however, there are rare forms that show remarkable spontaneous recoveries. Two homoplasmic mitochondrial tRNA mutations (m.14674T>C/G in mt-tRNA(Glu)) have been reported to cause severe infantile mitochondrial myopathy in the first months of life. If these patients survive the first year of life by extensive life-sustaining measures they usually recover and develop normally. Another mitochondrial disease due to deficiency of the 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) causes severe liver failure in infancy, but similar to the reversible mitochondrial myopathy, within the first year of life these infants may also recover completely. Partial recovery has been noted in some other rare forms of mitochondrial disease due to deficiency of mitochondrial tRNA synthetases and mitochondrial tRNA modifying enzymes. Here we summarize the clinical presentation of these unique reversible mitochondrial diseases and discuss potential molecular mechanisms behind the reversibility. Understanding these mechanisms may provide the key to treatments of potential broader relevance in mitochondrial disease, where for the majority of the patients no effective treatment is currently available.

  16. Anisotropy signature in extended images from reverse-time migration

    KAUST Repository

    Sava, Paul

    2012-11-04

    Reverse-time migration can accurately image complex geologic structures in anisotropic media. Extended images at selected locations in the earth, i.e. at common-image-point gathers (CIPs), carry enough information to characterize the angle-dependent illumination and to provide measurements for migration velocity analysis. Furthermore, inaccurate anisotropy leaves a distinctive signature in CIPs, which can be used to evaluate anisotropy through techniques similar to the ones used in conventional wavefield tomography.

  17. Anisotropy signature in extended images from reverse-time migration

    KAUST Repository

    Sava, Paul; Alkhalifah, Tariq Ali

    2012-01-01

    Reverse-time migration can accurately image complex geologic structures in anisotropic media. Extended images at selected locations in the earth, i.e. at common-image-point gathers (CIPs), carry enough information to characterize the angle-dependent illumination and to provide measurements for migration velocity analysis. Furthermore, inaccurate anisotropy leaves a distinctive signature in CIPs, which can be used to evaluate anisotropy through techniques similar to the ones used in conventional wavefield tomography.

  18. [Reversible infertility from nonsteroidal anti-inflammatory drugs].

    Science.gov (United States)

    Skomsvoll, Johan Fredrik; Rødevand, Erik; Koksvik, Hege Svean; Salvesen, Kjell Asmund; von Düring, Vidar; Rygnestad, Tarjei; Østensen, Monika

    2005-06-02

    Nonsteroidal anti-inflammatory drugs (NSAIDs) and selective cyclooxygenase-2 inhibitors may interfere with ovulation and the rupture of the follicle, causing reversible infertility. Literature review. Reversible infertility is shown both in animal and human studies of these drugs. As determined by ultrasound, the drugs may delay or inhibit ovulation. These findings are also confirmed by a few randomized controlled studies showing an increase in time from the luteinizing hormone surge to rupture of the follicle and an increased size of the unruptured follicle. Most of the hormone analyses show values in accordance with the ovulation/menstrual cycle. Also, two epidemiological studies have shown an association between NSAID use and spontaneous abortion. These studies have methodological weaknesses and their findings have to be elucidated in future studies. Women with fertility problems should avoid not only the selective cyclooxygenase-2 inhibitors, but also the traditional NSAIDs. However, women with rheumatic disease responding well to therapy should consult their physicians before stopping treatment. Reduced dose of a NSAID and temporary stop of drug treatment early in the menstrual cycle, or alternative drug treatment, may be a solution. NSAIDs should not be used in the last eight weeks of pregnancy.

  19. Rattleback dynamics and its reversal time of rotation

    Science.gov (United States)

    Kondo, Yoichiro; Nakanishi, Hiizu

    2017-06-01

    A rattleback is a rigid, semielliptic toy which exhibits unintuitive behavior; when it is spun in one direction, it soon begins pitching and stops spinning, then it starts to spin in the opposite direction, but in the other direction, it seems to spin just steadily. This puzzling behavior results from the slight misalignment between the principal axes for the inertia and those for the curvature; the misalignment couples the spinning with the pitching and the rolling oscillations. It has been shown that under the no-slip condition and without dissipation the spin can reverse in both directions, and Garcia and Hubbard obtained the formula for the time required for the spin reversal tr [Proc. R. Soc. Lond. A 418, 165 (1988), 10.1098/rspa.1988.0078]. In this work, we reformulate the rattleback dynamics in a physically transparent way and reduce it to a three-variable dynamics for spinning, pitching, and rolling. We obtain an expression of the Garcia-Hubbard formula for tr by a simple product of four factors: (1) the misalignment angle, (2) the difference in the inverses of inertia moment for the two oscillations, (3) that in the radii for the two principal curvatures, and (4) the squared frequency of the oscillation. We perform extensive numerical simulations to examine validity and limitation of the formula, and find that (1) the Garcia-Hubbard formula is good for both spinning directions in the small spin and small oscillation regime, but (2) in the fast spin regime especially for the steady direction, the rattleback may not reverse and shows a rich variety of dynamics including steady spinning, spin wobbling, and chaotic behavior reminiscent of chaos in a dissipative system.

  20. Differential geometric invariants for time-reversal symmetric Bloch-bundles: The “Real” case

    International Nuclear Information System (INIS)

    De Nittis, Giuseppe; Gomi, Kiyonori

    2016-01-01

    Topological quantum systems subjected to an even (resp. odd) time-reversal symmetry can be classified by looking at the related “Real” (resp. “Quaternionic”) Bloch-bundles. If from one side the topological classification of these time-reversal vector bundle theories has been completely described in De Nittis and Gomi [J. Geom. Phys. 86, 303–338 (2014)] for the “Real” case and in De Nittis and Gomi [Commun. Math. Phys. 339, 1–55 (2015)] for the “Quaternionic” case, from the other side it seems that a classification in terms of differential geometric invariants is still missing in the literature. With this article and its companion [G. De Nittis and K. Gomi (unpublished)] we want to cover this gap. More precisely, we extend in an equivariant way the theory of connections on principal bundles and vector bundles endowed with a time-reversal symmetry. In the “Real” case we generalize the Chern-Weil theory and we show that the assignment of a “Real” connection, along with the related differential Chern class and its holonomy, suffices for the classification of “Real” vector bundles in low dimensions.

  1. Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera[OPEN

    Science.gov (United States)

    Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S.; Johnson, Marc T.J.; Wright, Stephen I.; Pellizzer, Tommaso; Sobanski, Johanna; Greiner, Stephan

    2016-01-01

    Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. PMID:27053421

  2. Majorana bound states in two-channel time-reversal-symmetric nanowire systems

    DEFF Research Database (Denmark)

    Gaidamauskas, Erikas; Paaske, Jens; Flensberg, Karsten

    2014-01-01

    We consider time-reversal-symmetric two-channel semiconducting quantum wires proximity coupled to a conventional s-wave superconductor. We analyze the requirements for a non-trivial topological phase, and find that necessary conditions are 1) the determinant of the pairing matrix in channel space...

  3. Deformation effect and five-fold correlation time reversal test in neutron resonances using aligned 165Ho

    International Nuclear Information System (INIS)

    Huffman, P.R.; Roberson, N.R.; Gould, C.R.; Haase, D.G.

    1993-01-01

    In 1988, Bunakov proposed a test of parity (P) even time reversal (T) violation in the neighborhood of two interfering p-wave resonances of the same spin. A similar enhancement exists if a d-wave and s-wave resonance interfere. Until now, however, no suitable resonances have been located in nuclei which can be aligned, and the only tests of time reversal violation in neutron transmission have been carried out with MeV-energy neutrons. The authors estimate the deformation effect cross sections for neutron resonances in aligned 165 Ho, and estimate the sensitivity of a five-fold correlation time reversal test carried out on a resonance that exhibits a deformation effect

  4. Time reversal odd fragmentation functions in semi-inclusive deep inelastic lepton-hadron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Mulders, P.J. [National Inst. for Nuclear Physics and High Energy Physics, Amsterdam (Netherlands); Levelt, J. [Univ. of Erlangen-Nuernberg (Germany)

    1994-04-01

    In semi-inclusive scattering of polarized leptons from unpolarized hadrons, one can measure a time reversal odd structure function. It shows up as a sin({phi}) asymmetry of the produced hadrons. This asymmetry can be expressed as the product of a twist-three {open_quotes}hadron {r_arrow} quark{close_quotes} profile function and a time reversal odd twist-two {open_quotes}quark {r_arrow} hadron{close_quotes} fragmentation function. This fragmentation function can only be measured for nonzero transverse momenta of the produced hadron. Its appearance is a consequence of final state interactions between the produced hadron and the rest of the final state.

  5. Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

    Science.gov (United States)

    Hedqvist, Anders; Rachlew-Källne, Elisabeth

    1998-09-01

    Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and 0741-3335/40/9/004/img1 together with a description of the interpretation and the equipment are presented.

  6. Do children report differently from their parents and from observed data? Cross-sectional data on fruit, water, sugar-sweetened beverages and break-time foods

    Directory of Open Access Journals (Sweden)

    V. M. van de Gaar

    2016-04-01

    Full Text Available Abstract Background Reliable assessment of children’s dietary behaviour is needed for research purposes. The aim of this study was (1 to investigate the level of agreement between observed and child-reported break-time food items; and (2 to investigate the level of agreement between children’s reports and those of their parents regarding children’s overall consumption of fruit, water and sugar-sweetened beverages (SSB. Methods The children in this study were 9–13 years old, attending primary schools in Rotterdam, the Netherlands. Children were observed with respect to foods brought for break-time at school. At the same day, children completed a questionnaire in which they were asked to recall the food(s they brought to school to consume during break-time. Only paired data (observed and child-reported were included in the analyses (n = 407 pairs. To determine each child’s daily consumption and average amounts of fruit, water and SSB consumed, children and their parents completed parallel questionnaires. Only paired data (parent-reported and child-reported were included in the analyses (n = 275 pairs. The main statistical measures were level of agreement between break-time foods, fruit, water and SSB; and Intra-class Correlation Coefficients (ICC. Results More children reported bringing sandwiches and snacks for break-time than was observed (73 % vs 51 % observed and 84 % vs 33 % observed. The overall agreement between observed and child-reported break-time foods was poor to fair, with ICC range 0.16–0.39 (p < 0.05. Children reported higher average amounts of SSB consumed than did their parents (1.3 vs 0.9 L SSB, p < 0.001. Child and parent estimations of the child’s water and fruit consumption were similar. ICC between parent and child reports was poor to good (range 0.22–0.62, p < 0.05. Conclusion Children report higher on amount of break-time foods as compared to observations and children’s reports of

  7. Reverse Algols

    Science.gov (United States)

    Leung, K. C.

    1989-01-01

    Reverse Algols, binary systems with a semidetached configuration in which the more massive component is in contact with the critical equipotential surface, are examined. Observational evidence for reverse Algols is presented and the parameters of seven reverse Algols are listed. The evolution of Algols and reverse Algols is discussed. It is suggested that, because reverse Algols represent the premass-reversal semidetached phase of close binary evolution, the evolutionary time scale between regular and reverse Algols is the ratio of the number of confirmed systems of these two Algol types.

  8. Real-Time Dynamics in U(1 Lattice Gauge Theories with Tensor Networks

    Directory of Open Access Journals (Sweden)

    T. Pichler

    2016-03-01

    Full Text Available Tensor network algorithms provide a suitable route for tackling real-time-dependent problems in lattice gauge theories, enabling the investigation of out-of-equilibrium dynamics. We analyze a U(1 lattice gauge theory in (1+1 dimensions in the presence of dynamical matter for different mass and electric-field couplings, a theory akin to quantum electrodynamics in one dimension, which displays string breaking: The confining string between charges can spontaneously break during quench experiments, giving rise to charge-anticharge pairs according to the Schwinger mechanism. We study the real-time spreading of excitations in the system by means of electric-field and particle fluctuations. We determine a dynamical state diagram for string breaking and quantitatively evaluate the time scales for mass production. We also show that the time evolution of the quantum correlations can be detected via bipartite von Neumann entropies, thus demonstrating that the Schwinger mechanism is tightly linked to entanglement spreading. To present a variety of possible applications of this simulation platform, we show how one could follow the real-time scattering processes between mesons and the creation of entanglement during scattering processes. Finally, we test the quality of quantum simulations of these dynamics, quantifying the role of possible imperfections in cold atoms, trapped ions, and superconducting circuit systems. Our results demonstrate how entanglement properties can be used to deepen our understanding of basic phenomena in the real-time dynamics of gauge theories such as string breaking and collisions.

  9. On the ether-like Lorentz-breaking actions

    International Nuclear Information System (INIS)

    Petrov, A.Yu; Nascimento, J.R.; Gomes, M.; Silva, A. J. da

    2011-01-01

    We demonstrate the generation of the CPT-even, ether-like Lorentz-breaking actions for the scalar and electro-magnetic fields via their appropriate Lorentz-breaking coupling to spinor fields in three, four and five space-time dimensions. Besides, we show that the ether-like terms for the spinor field also can be generated as a consequence of the same couplings. The key result which will be presented here is the finiteness of the ether-like term for the electromagnetic field not only in three and five space-time dimensions where it is natural due to known effects of the dimensional regularization but also in four space-time dimensions. Moreover, we present the calculation of the last result within different calculational schemes and conclude that the result for the four-dimensional ether-like term for the electromagnetic field essentially depending on the calculation scheme, similarly to the result for the Carroll-Field-Jackiw (CFJ) term which probably signalizes a possibility for arising of a new anomaly. Also we discuss the dispersion relations in the theories with ether-like Lorentz-breaking terms which allows to discuss the consistency of the Lorentz-breaking modified theories for different (space-like or time-like) Lorentz-breaking vectors and find the tree-level effective (Breit) potential for fermion scattering and the one-loop effective potential corresponding to the action of the scalar field. (author)

  10. Induction of spontaneous and UV-induced mutations during commitment to meiosis in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Machida, I.; Nakai, S.

    1980-01-01

    Inductions of reversions of nonsense, missense and frameshift-type mutations were investigated in a diploid cell population of Saccharomyces cerevisiae during commitment to meiosis, by using the medium-transfer technique from sporulation medium to vegetative medium. The yields of spontaneous reverse mutations obtained from the cells that were committed to different stages during meiosis were rather constant irrespective of the alleles tested, although the yields of both intergenic and intragenic recombinations markedly increased. The susceptibilities to UV-induced reverse mutations examined during commitment to meiosis were not changed appreciably. It is concluded that induction of base-change-type mutations in meiosis is not essentially different from that in mitosis. (orig.)

  11. Electroweak symmetry breaking: Higgs/whatever

    International Nuclear Information System (INIS)

    Chanowitz, M.S.

    1990-01-01

    In these two lectures the author discusses electroweak symmetry breaking from a general perspective, stressing properties that are model independent and follow just from the assumption that the electroweak interactions are described by a spontaneously broken gauge theory. This means he assumes the Higgs mechanism though not necessarily the existence of Higgs bosons. The first lecture presents the general framework of a spontaneously broken gauge theory: (1) the Higgs mechanism sui generis, with or without Higgs boson(s) and (2) the implications of symmetry and unitarity for the mass scale and interaction strength of the new physics that the Higgs mechanism requires. In addition he reviews a softer theoretical argument based on the naturalness problem which leads to a prejudice against Higgs bosons unless they are supersymmetric. This is a prejudice, not a theorem, and it could be overturned in the future by a clever new idea. In the second lecture he illustrates the general framework by reviewing some specific models: (1) the Weinberg-Salam model of the Higgs sector; (2) the minimal supersymmetric extension of the Weinberg-Salam model; and (3) technicolor as an example of the Higgs mechanism without Higgs bosons. He concludes the second lecture with a discussion of strong WW scattering that must occur if L SB lives above 1 TeV. In particular he describes some of the experimental signals and backgrounds at the SSC. 57 refs., 12 figs

  12. Time reversal mirror and perfect inverse filter in a microscopic model for sound propagation

    International Nuclear Information System (INIS)

    Calvo, Hernan L.; Danieli, Ernesto P.; Pastawski, Horacio M.

    2007-01-01

    Time reversal of quantum dynamics can be achieved by a global change of the Hamiltonian sign (a hasty Loschmidt daemon), as in the Loschmidt Echo experiments in NMR, or by a local but persistent procedure (a stubborn daemon) as in the time reversal mirror (TRM) used in ultrasound acoustics. While the first is limited by chaos and disorder, the last procedure seems to benefit from it. As a first step to quantify such stability we develop a procedure, the perfect inverse filter (PIF), that accounts for memory effects, and we apply it to a system of coupled oscillators. In order to ensure a numerical many-body dynamics intrinsically reversible, we develop an algorithm, the pair partitioning, based on the Trotter strategy used for quantum dynamics. We analyze situations where the PIF gives substantial improvements over the TRM

  13. Flowering responses to light-breaks in photomorphogenic mutants of Arabidopsis thaliana, a long-day plant

    International Nuclear Information System (INIS)

    Goto, N.; Kumagai, T.; Koornneef, M.

    1991-01-01

    Flowering response and plant form of photomorphogenic mutants (hy1, hy2, hy3, hy4 and hy5) of Arabidopsis thaliana (L.), a long-day plant, were examined in long and short days. There were only slight differences among genotypes including Landsberg wild type with respect to the flowering time under long days. The effect of 1 h light-(night)-breaks of far-red, red, blue and white light given in the middle of the dark period of plants grown under short days, was studied. Effects of far-red light applied at the end or the beginning of the main photoperiod on flowering and plant form were also examined. The light-breaks with all the above mentioned light qualities promoted floral initiation of all the genotypes including the wild type in terms of both the flowering time and the number of rosette leaves. In general, far-red light was most effective. It is possible to classify the hy-mutants into 3 groups by their responses to light-breaks under short day conditions: (a) Mutants hy2 and hy3, which have a reduced number of rosette leaves, and flower early. Red light is as effective as far-red light. The wavelength of light-breaks is relatively unimportant for flowering response. (b) Mutants hy4, hy5 and Landsberg wild type, which have a greater number of rosette leaves, and flower relatively late. The effectiveness of light-breaks is in the following order, far-red, blue, and red light, which is in reverse order to the transformation of phytochrome to the P fr form. (c) Mutant hy1, which behaves anomalously with respect to relations between flowering time and number of rosette leaves; late flowering with reduced number of rosette leaves. Red, blue and far-red light are effective, but white light is ineffective for reducing the number of rosette leaves. When far-red light was given in the middle of the night or at the end of the main photoperiod, it markedly reduced the number of rosette leaves compared to those grown under short days for all the genotypes, while when

  14. Precise discussion of time-reversal asymmetries in B-meson decays

    International Nuclear Information System (INIS)

    Morozumi, Takuya; Okane, Hideaki; Umeeda, Hiroyuki

    2015-01-01

    BaBar collaboration announced that they observed time reversal (T) asymmetry through B meson system. In the experiment, time dependencies of two distinctive processes, B_−→ (B"0)-bar and (B"0)-bar →B_− (− expresses CP value) are compared with each other. In our study, we examine event number difference of these two processes. In contrast to the BaBar asymmetry, the asymmetry of events number includes the overall normalization difference for rates. Time dependence of the asymmetry is more general and it includes terms absent in one used by BaBar collaboration. Both of the BaBar asymmetry and ours are naively thought to be T-odd since two processes compared are related with flipping time direction. We investigate the time reversal transformation property of our asymmetry. Using our notation, one can see that the asymmetry is not precisely a T-odd quantity, taking into account indirect CP and CPT violation of K meson systems. The effect of ϵ_K is extracted and gives rise to O(10"−"3) contribution. The introduced parameters are invariant under rephasing of quarks so that the coefficients of our asymmetry are expressed as phase convention independent quantities. Some combinations of the asymmetry enable us to extract parameters for wrong sign decays of B_d meson, CPT violation, etc. We also study the reason why the T-even terms are allowed to contribute to the asymmetry, and find that several conditions are needed for the asymmetry to be a T-odd quantity.

  15. Normalization sum rule and spontaneous breaking of U(N) invariance in random matrix ensembles

    International Nuclear Information System (INIS)

    Canali, C.M.; Kravtsov, V.E.

    1995-03-01

    It is shown that the two-level correlation function R(s,s') in the invariant random matrix ensembles (RME) with soft confinement exhibits a ''ghost peak'' at s approx. -s'. This lifts the sum rule prohibition for the level number variance to have a Poisson-like term var(n) = ηn that is typical of RME with broken U(N) symmetry. Thus we conclude that the U(N) invariance is broken spontaneously in the RME with soft confinement, η playing the role of an order-parameter. (author). 16 refs, 1 fig

  16. Cell cycle checkpoints: reversible when possible, irreversible when needed

    NARCIS (Netherlands)

    Krenning, L.

    2015-01-01

    Cell cycle checkpoints are reversible in nature, and can prevent progression into the next cell cycle phase if needed. In the case of DNA damage, cells can prevent progression from G1 into S phase, and from G2 into mitosis in the presence of DNA double strand breaks. Following DNA repair, these

  17. The spontaneous formation of single-molecule junctions via terminal alkynes

    International Nuclear Information System (INIS)

    Pla-Vilanova, Pepita; Aragonès, Albert C; Sanz, Fausto; Darwish, Nadim; Diez-Perez, Ismael; Ciampi, Simone

    2015-01-01

    Herein, we report the spontaneous formation of single-molecule junctions via terminal alkyne contact groups. Self-assembled monolayers that form spontaneously from diluted solutions of 1, 4-diethynylbenzene (DEB) were used to build single-molecule contacts and assessed using the scanning tunneling microscopy-break junction technique (STM-BJ). The STM-BJ technique in both its dynamic and static approaches was used to characterize the lifetime (stability) and the conductivity of a single-DEB wire. It is demonstrated that single-molecule junctions form spontaneously with terminal alkynes and require no electrochemical control or chemical deprotonation. The alkyne anchoring group was compared against typical contact groups exploited in single-molecule studies, i.e. amine (benzenediamine) and thiol (benzendithiol) contact groups. The alkyne contact showed a conductance magnitude comparable to that observed with amine and thiol groups. The lifetime of the junctions formed from alkynes were only slightly less than that of thiols and greater than that observed for amines. These findings are important as (a) they extend the repertoire of chemical contacts used in single-molecule measurements to 1-alkynes, which are synthetically accessible and stable and (b) alkynes have a remarkable affinity toward silicon surfaces, hence opening the door for the study of single-molecule transport on a semiconducting electronic platform. (fast track communication)

  18. Least-squares reverse time migration of marine data with frequency-selection encoding

    KAUST Repository

    Dai, Wei; Huang, Yunsong; Schuster, Gerard T.

    2013-01-01

    The phase-encoding technique can sometimes increase the efficiency of the least-squares reverse time migration (LSRTM) by more than one order of magnitude. However, traditional random encoding functions require all the encoded shots to share

  19. Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera.

    Science.gov (United States)

    Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S; Zupok, Arkadiusz; Johnson, Marc T J; Wright, Stephen I; Pellizzer, Tommaso; Sobanski, Johanna; Bock, Ralph; Greiner, Stephan

    2016-04-01

    Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. © 2016 American Society of Plant Biologists. All rights reserved.

  20. Hyperscaling violation and electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Elander, Daniel, E-mail: pelander@purdue.edu [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States); Lawrance, Robert; Piai, Maurizio [Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, Wales (United Kingdom)

    2015-08-15

    We consider a class of simplified models of dynamical electroweak symmetry breaking built in terms of their five-dimensional weakly-coupled gravity duals, in the spirit of bottom-up holography. The sigma-model consists of two abelian gauge bosons and one real, non-charged scalar field coupled to gravity in five dimensions. The scalar potential is a simple exponential function of the scalar field. The background metric resulting from solving the classical equations of motion exhibits hyperscaling violation, at least at asymptotically large values of the radial direction. We study the spectrum of scalar composite states of the putative dual field theory by fluctuating the sigma-model scalars and gravity, and discuss in which cases we find a parametrically light scalar state in the spectrum. We model the spontaneous breaking of the (weakly coupled) gauge symmetry to the diagonal subgroup by the choice of IR boundary conditions. We compute the mass spectrum of spin-1 states, and the precision electroweak parameter S as a function of the hyperscaling coefficient. We find a general bound on the mass of the lightest spin-1 resonance, by requiring that the indirect bounds on the precision parameters be satisfied, that implies that precision electroweak physics excludes the possibility of a techni-rho meson with mass lighter than several TeV.

  1. Time reversal in photoacoustic tomography and levitation in a cavity

    International Nuclear Information System (INIS)

    Palamodov, V P

    2014-01-01

    A class of photoacoustic acquisition geometries in R n is considered such that the spherical mean transform admits an exact filtered back projection reconstruction formula. The reconstruction is interpreted as a time reversion mirror that reproduces exactly an arbitrary source distribution in the cavity. A series of examples of non-uniqueness of the inverse potential problem is constructed based on the same geometrical technique. (paper)

  2. Effective Lagrangians and parity-conserving time-reversal violation at low energies

    International Nuclear Information System (INIS)

    Engel, J.; Frampton, P.H.; Springer, R.P.

    1996-01-01

    Using effective Lagrangians, we argue that any time-reversal-violating but parity-conserving effects are too small to be observed in flavor-conserving nuclear processes without dramatic improvement in experimental accuracy. In the process we discuss other arguments that have appeared in the literature. copyright 1996 The American Physical Society

  3. Control of the symmetry breaking in double-well potentials by the resonant nonlinearity management

    International Nuclear Information System (INIS)

    Nistazakis, H. E.; Frantzeskakis, D. J.; Malomed, B. A.; Kevrekidis, P. G.

    2011-01-01

    We introduce a one-dimensional model of Bose-Einstein condensates (BECs), combining the double-well potential, which is a usual setting for the onset of spontaneous-symmetry-breaking (SSB) effects, and time-periodic modulation of the nonlinearity, which may be implemented by means of the Feshbach-resonance-management (FRM) technique. Both cases of the nonlinearity that is repulsive or attractive on the average are considered. In the former case, the main effect produced by the application of the FRM is spontaneous self-trapping of the condensate in either of the two potential wells in parameter regimes where it would remain untrapped in the absence of the management. In the weakly nonlinear regime, the frequency of intrinsic oscillations in the FRM-induced trapped state is very close to half the FRM frequency, suggesting that the effect is accounted for by a parametric resonance. In the case of the attractive nonlinearity, the FRM-induced effect is the opposite, i.e., enforced detrapping of a state which is self-trapped in its unmanaged form. In the latter case, the frequency of oscillations of the untrapped mode is close to a quarter of the driving frequency, suggesting that a higher-order parametric resonance may account for this effect.

  4. Structural Break Tests Robust to Regression Misspecification

    Directory of Open Access Journals (Sweden)

    Alaa Abi Morshed

    2018-05-01

    Full Text Available Structural break tests for regression models are sensitive to model misspecification. We show—analytically and through simulations—that the sup Wald test for breaks in the conditional mean and variance of a time series process exhibits severe size distortions when the conditional mean dynamics are misspecified. We also show that the sup Wald test for breaks in the unconditional mean and variance does not have the same size distortions, yet benefits from similar power to its conditional counterpart in correctly specified models. Hence, we propose using it as an alternative and complementary test for breaks. We apply the unconditional and conditional mean and variance tests to three US series: unemployment, industrial production growth and interest rates. Both the unconditional and the conditional mean tests detect a break in the mean of interest rates. However, for the other two series, the unconditional mean test does not detect a break, while the conditional mean tests based on dynamic regression models occasionally detect a break, with the implied break-point estimator varying across different dynamic specifications. For all series, the unconditional variance does not detect a break while most tests for the conditional variance do detect a break which also varies across specifications.

  5. Defining Nitrogen Kinetics for Air Break in Prebreathe

    Science.gov (United States)

    Conkin, Johnny

    2009-01-01

    Actual tissue nitrogen (N2) kinetics are complex; the uptake and elimination is often approximated with a single half-time compartment in statistical descriptions of denitrogenation [prebreathe (PB)] protocols. Air breaks during PB complicate N2 kinetics. A comparison of symmetrical versus asymmetrical N2 kinetics was performed using the time to onset of hypobaric decompression sickness (DCS) as a surrogate for actual venous N2 tension. Published results of 12 tests involving 179 hypobaric exposures in altitude chambers after PB, with and without air breaks, provide the complex protocols from which to model N2 kinetics. DCS survival time for combined control and air breaks were described with an accelerated log logistic model where N2 uptake and elimination before, during, and after the air break was computed with a simple exponential function or a function that changed half-time depending on ambient N2 partial pressure. P1N2-P2 = delta P defined DCS dose for each altitude exposure, where P2 was the test altitude and P1N2 was computed N2 pressure at the beginning of the altitude exposure. The log likelihood (LL) without DCS dose (null model) was -155.6, and improved (best-fit) to -97.2 when dose was defined with a 240 min half-time for both N2 elimination and uptake during the PB. The description of DCS survival time was less precise with asymmetrical N2 kinetics, for example, LL was -98.9 with 240 min half-time elimination and 120 min half-time uptake. The statistical regression described survival time mechanistically linked to symmetrical N2 kinetics during PBs that also included air breaks. The results are data-specific, and additional data may change the conclusion. The regression is useful to compute additional PB time to compensate for an air break in PB within the narrow range of tested conditions.

  6. Search for spontaneous fission of 226Ra and systematics of the spontaneous fission, α-decay and cluster decay probabilities

    International Nuclear Information System (INIS)

    Mikheev, V.L.; Tret'yakova, S.P.; Golovchenko, A.N.; Timofeeva, O.V.; Hussonnois, M.; Le Naour, C.

    1998-01-01

    The low limit of the 226 Ra spontaneous fission half-life corresponding to T 1/2 ≥ 4 · 10 18 years is measured. The 226 Ra spontaneous fission probability proved to be about 50 times less than the value expected from the known systematics, connecting the ratios of theα-decay and spontaneous fission probabilities with the fissility parameter Z 2 /A. It is shown that the probabilities of spontaneous fission, α-decay and cluster decay can be systematized in the same way according to the difference between the decay products Coulomb energy near the scission point and decay energy Q

  7. An Analysis of Effect of Break-up Timing on the Necessity of a Feed-and-Bleed Operation in the case of TLOFW with Local

    International Nuclear Information System (INIS)

    Kim, Bo Gyung; Kim, Sang Ho; Kang, Hyun Gook; Yoon, Ho Joon

    2014-01-01

    A Feed-and-bleed (F and B) operation is a process to cool the reactor by the primary side directly. If adequate residual heat removal through the secondary side is not available, the heat can be removed from the RCS by F and B operation. A total loss of feedwater (TLOFW) accident is used to represent an accident involving the failure of cooling by the secondary cooling system. Even if the secondary cooling system fails, the RCS can be cooled by F and B transients when a loss of coolant accident (LOCA) with a TLOFW accident occurs. During an F and B transient, the RCS has a residual heat removal mechanism. If the break size is large, an F and B transient continuously occurs if the SIS is available. If the break size is small to sufficiently decrease the RCS pressure, the SIS cannot inject the coolant, causing the F and B transient to terminate. After the termination of the F and B transient, the residual heat cannot be removed, and the necessity of an F and B operation increases. The operators may hesitate to initiate F and B operation if a clear cue is not provided, since its initiation implies the radioactive coolant releases into the containment. Therefore, the necessity of F and B operation is needed to be identified. The factors affected the necessity of F and B operation are the availability of the safety injection system and safety depressurization system, water inventory in the primary and secondary cooling systems, break size in a loss-of-coolant accident, and time of accident occurrence. The necessity of F and B operation can be changed according to different timing of break-up despite same break size. Moreover, different timing of break-up makes the operators more complicated. To identify effect of timing of break-up, a thermohydraulic analysis was performed using the MARS code. This study is expected to provide a useful guideline to identify the necessity of an F and B operation under combined accident

  8. A Reverse Shock in GRB 160509A

    Science.gov (United States)

    Laskar, Tanmoy; Alexander, Kate D.; Berger, Edo; Fong, Wen-fai; Margutti, Raffaella; Shivvers, Isaac; Williams, Peter K. G.; Kopač, Drejc; Kobayashi, Shiho; Mundell, Carole; Gomboc, Andreja; Zheng, WeiKang; Menten, Karl M.; Graham, Melissa L.; Filippenko, Alexei V.

    2016-12-01

    We present the second multi-frequency radio detection of a reverse shock in a γ-ray burst. By combining our extensive radio observations of the Fermi-Large Area Telescope γ-ray burst 160509A at z = 1.17 up to 20 days after the burst with Swift X-ray observations and ground-based optical and near-infrared data, we show that the afterglow emission comprises distinct reverse shock and forward shock contributions: the reverse shock emission dominates in the radio band at ≲10 days, while the forward shock emission dominates in the X-ray, optical, and near-infrared bands. Through multi-wavelength modeling, we determine a circumburst density of {n}0≈ {10}-3 {{cm}}-3, supporting our previous suggestion that a low-density circumburst environment is conducive to the production of long-lasting reverse shock radiation in the radio band. We infer the presence of a large excess X-ray absorption column, N H ≈ 1.5 × 1022 {{cm}}-2, and a high rest-frame optical extinction, A V ≈ 3.4 mag. We identify a jet break in the X-ray light curve at {t}{jet}≈ 6 {days}, and thus derive a jet opening angle of {θ }{jet}≈ 4^\\circ , yielding a beaming-corrected kinetic energy and radiated γ-ray energy of {E}{{K}}≈ 4× {10}50 erg and {E}γ ≈ 1.3× {10}51 erg (1-104 keV, rest frame), respectively. Consistency arguments connecting the forward shocks and reverse shocks suggest a deceleration time of {t}{dec} ≈ 460 s ≈ T 90, a Lorentz factor of {{Γ }}({t}{dec})≈ 330, and a reverse-shock-to-forward-shock fractional magnetic energy density ratio of {R}{{B}}\\equiv {ɛ }{{B},{RS}}/{ɛ }{{B},{FS}}≈ 8. Our study highlights the power of rapid-response radio observations in the study of the properties and dynamics of γ-ray burst ejecta.

  9. Magnetization reversal in an obliquely oriented metal evaporated tape

    International Nuclear Information System (INIS)

    Srinath, S.; Vavassori, P.; Rekveldt, M.Th.; Cook, R.E.; Felcher, G.P.

    2004-01-01

    Magnetization reversal in obliquely oriented metal evaporated videotapes as a function of the tape depth was studied by vector magneto-optic Kerr effect and polarized neutron reflectivity. The magnetization vector was found to rotate coherently out-of-plane by an angle α during the magnetization reversal for a substantial part of the hysteresis cycle. However α differs between the surface-facing and the substrate-facing sides of the film, with the more oxidized surface layer following closely the applied field. Close to M∼0 the film breaks down magnetically into a collage of small domains, reflecting the crystalline microstructure of the material

  10. Breaking Immunological Tolerance through OX40 (CD134

    Directory of Open Access Journals (Sweden)

    Pratima Bansal-Pakala

    2001-01-01

    Full Text Available Immunological tolerance represents a mechanism by which cells of the host remain protected from the immune system. Breaking of immunological tolerance can result in a variety of autoimmune diseases such as rheumatoid arthritis, diabetes, and multiple sclerosis. The reasons for tolerance breaking down and autoimmune processes arising are largely unknown but of obvious interest for therapeutic intervention of these diseases. Although reversal of the tolerant state is generally unwanted, there are instances where this may be of benefit to the host. In particular, one way a cancerous cell escapes being targeted by the immune system is through tolerance mechanisms that in effect turn off the reactivity of T lymphocytes that can respond to tumor-associated peptides. Thus tolerance represents a major obstacle in developing effective immunotherapy against tumors. The molecules that are involved in regulating immunological tolerance are then of interest as they may be great targets for positively or negatively manipulating the tolerance process.

  11. Interstrand cross-links arising from strand breaks at true abasic sites in duplex DNA

    OpenAIRE

    Yang, Zhiyu; Price, Nathan E.; Johnson, Kevin M.; Wang, Yinsheng; Gates, Kent S.

    2017-01-01

    Abstract Interstrand cross-links are exceptionally bioactive DNA lesions. Endogenous generation of interstrand cross-links in genomic DNA may contribute to aging, neurodegeneration, and cancer. Abasic (Ap) sites are common lesions in genomic DNA that readily undergo spontaneous and amine-catalyzed strand cleavage reactions that generate a 2,3-didehydro-2,3-dideoxyribose sugar remnant (3?ddR5p) at the 3?-terminus of the strand break. Interestingly, this strand scission process leaves an electr...

  12. Time reversal and the neutron

    International Nuclear Information System (INIS)

    Chupp, T. E.; Cooper, R. L.; Coulter, K. P.; Freedman, S. J.; Fujikawa, B. K.; Jones, G. L.; Garcia, A.; Mumm, H. P.; Nico, J. S.; Thompson, A. K.; Trull, C.; Wietfeldt, F. E.; Wilkerson, J. F.

    2013-01-01

    We have measured the triple correlation D n >/J n ·(β e x p-hat ν ) with a polarized cold-neutron beam (Mumm et al., Phys Rev Lett 107:102301, 2011; Chupp et al., Phys Rev C 86:035505, 2012). A non-zero value of D can arise due to parity-even-time-reversal-odd interactions that imply CP violation. Final-state effects also contribute to D at the level of 10  − 5 and can be calculated with precision of 1 % or better. The D coefficient is uniquely sensitive to the imaginary part of the ratio of axial-vector and vector beta-decay amplitudes as well as to scalar and tensor interactions that could arise due to beyond-Standard-Model physics. Over 300 million proton-electron coincidence events were used in a blind analysis with the result D = [ − 0.94±1.89 (stat)±0.97(sys)]×10  − 4 . Assuming only vector and axial vector interactions in beta decay, our result can be interpreted as a measure of the phase of the axial-vector coupling relative to the vector coupling, φ AV = 180.012 ° ± 0.028 °. This result also improves constrains on certain non-VA interactions.

  13. Time reversal and the neutron

    Energy Technology Data Exchange (ETDEWEB)

    Chupp, T. E., E-mail: chupp@umich.edu; Cooper, R. L.; Coulter, K. P. [Univeristy of Michigan (United States); Freedman, S. J.; Fujikawa, B. K. [University of California and Lawrence Berkeley Laboratory (United States); Jones, G. L. [Hamilton College (United States); Garcia, A. [University of Washington (United States); Mumm, H. P.; Nico, J. S.; Thompson, A. K. [National Institute of Standards and Technology (United States); Trull, C.; Wietfeldt, F. E. [Tulane University (United States); Wilkerson, J. F. [University of North Carolina (United States); Collaboration: emiT II Collaboration

    2013-03-15

    We have measured the triple correlation D/J{sub n}{center_dot}({beta}{sub e} x p-hat{sub {nu}}) with a polarized cold-neutron beam (Mumm et al., Phys Rev Lett 107:102301, 2011; Chupp et al., Phys Rev C 86:035505, 2012). A non-zero value of D can arise due to parity-even-time-reversal-odd interactions that imply CP violation. Final-state effects also contribute to D at the level of 10{sup - 5} and can be calculated with precision of 1 % or better. The D coefficient is uniquely sensitive to the imaginary part of the ratio of axial-vector and vector beta-decay amplitudes as well as to scalar and tensor interactions that could arise due to beyond-Standard-Model physics. Over 300 million proton-electron coincidence events were used in a blind analysis with the result D = [ - 0.94{+-}1.89 (stat){+-}0.97(sys)] Multiplication-Sign 10{sup - 4}. Assuming only vector and axial vector interactions in beta decay, our result can be interpreted as a measure of the phase of the axial-vector coupling relative to the vector coupling, {phi}{sub AV} = 180.012 Degree-Sign {+-} 0.028 Degree-Sign . This result also improves constrains on certain non-VA interactions.

  14. Time Reversal Acoustic Structural Health Monitoring Using Array of Embedded Sensors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Time Reversal Acoustic (TRA) structural health monitoring with an embedded sensor array represents a new approach to in-situ nondestructive evaluation of air-space...

  15. Effect of vacuum arc cathode spot distribution on breaking capacity of the arc-extinguishing chamber

    Science.gov (United States)

    Ding, Can; Yuan, Zhao; He, Junjia

    2017-10-01

    A DC circuit breaker performs a key function in breaking an intermediate-frequency (IF) current since breaking a pure IF current is equivalent to breaking a very small DC with a reverse IF current. In this study, it is found that cathode spots show a ring-shaped distribution at 2000 Hz. An arc with an uneven distribution of cathode spots has been simulated. The simulation results show that the distribution of cathode spots significantly affect the microparameter distribution of arc plasma. The current distribution on the anode side differs from that on the cathode side under the total radial electric field. Specifically, the anode current distribution is both uneven and concentrated. The applied axial magnetic field, which cannot reduce the concentrated anode current distribution effectively, might increase the concentration of the anode current. Finally, the uneven distribution of cathode spots reduces the breaking capacity of the arc-extinguishing chamber.

  16. Discrete time-crystalline order in black diamond

    Science.gov (United States)

    Zhou, Hengyun; Choi, Soonwon; Choi, Joonhee; Landig, Renate; Kucsko, Georg; Isoya, Junichi; Jelezko, Fedor; Onoda, Shinobu; Sumiya, Hitoshi; Khemani, Vedika; von Keyserlingk, Curt; Yao, Norman; Demler, Eugene; Lukin, Mikhail D.

    2017-04-01

    The interplay of periodic driving, disorder, and strong interactions has recently been predicted to result in exotic ``time-crystalline'' phases, which spontaneously break the discrete time-translation symmetry of the underlying drive. Here, we report the experimental observation of such discrete time-crystalline order in a driven, disordered ensemble of 106 dipolar spin impurities in diamond at room-temperature. We observe long-lived temporal correlations at integer multiples of the fundamental driving period, experimentally identify the phase boundary and find that the temporal order is protected by strong interactions; this order is remarkably stable against perturbations, even in the presence of slow thermalization. Our work opens the door to exploring dynamical phases of matter and controlling interacting, disordered many-body systems.

  17. Spontaneous cooperation for prosocials, but not for proselfs: Social value orientation moderates spontaneous cooperation behavior

    Science.gov (United States)

    Mischkowski, Dorothee; Glöckner, Andreas

    2016-01-01

    Cooperation is essential for the success of societies and there is an ongoing debate whether individuals have therefore developed a general spontaneous tendency to cooperate or not. Findings that cooperative behavior is related to shorter decision times provide support for the spontaneous cooperation effect, although contrary results have also been reported. We show that cooperative behavior is better described as person × situation interaction, in that there is a spontaneous cooperation effect for prosocial but not for proself persons. In three studies, one involving population representative samples from the US and Germany, we found that cooperation in a public good game is dependent on an interaction between individuals’ social value orientation and decision time. Increasing deliberation about the dilemma situation does not affect persons that are selfish to begin with, but it is related to decreasing cooperation for prosocial persons that gain positive utility from outcomes of others and score high on the related general personality trait honesty/humility. Our results demonstrate that the spontaneous cooperation hypothesis has to be qualified in that it is limited to persons with a specific personality and social values. Furthermore, they allow reconciling conflicting previous findings by identifying an important moderator for the effect. PMID:26876773

  18. Splitting of the rate matrix as a definition of time reversal in master equation systems

    International Nuclear Information System (INIS)

    Liu Fei; Le, Hong

    2012-01-01

    Motivated by recent progress in nonequilibrium fluctuation relations, we present a generalized time reversal for stochastic master equation systems with discrete states, which is defined as a splitting of the rate matrix into irreversible and reversible parts. An immediate advantage of this definition is that a variety of fluctuation relations can be attributed to different matrix splittings. Additionally, we find that the accustomed total entropy production formula and conditions of the detailed balance must be modified appropriately to account for the reversible rate part, which was previously ignored. (paper)

  19. Measuring the spin Chern number in time-reversal-invariant Hofstadter optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dan-Wei, E-mail: zdanwei@126.com [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006 (China); Cao, Shuai, E-mail: shuaicao2004@163.com [Department of Applied Physics, College of Electronic Engineering, South China Agricultural University, Guangzhou 510642 China (China)

    2016-10-14

    We propose an experimental scheme to directly measure the spin Chern number of the time-reversal-invariant Hofstadter model in optical lattices. We first show that this model can be realized by using ultracold Fermi atoms with two pseudo-spin states encoded by the internal Zeeman states in a square optical lattice and the corresponding topological Bloch bands are characterized by the spin Chern number. We then propose and numerically demonstrate that this topological invariant can be extracted from the shift of the hybrid Wannier center in the optical lattice. By spin-resolved in situ detection of the atomic densities along the transverse direction combined with time-of-flight measurement along another spatial direction, the spin Chern number in this system is directly measured. - Highlights: • The cold-atom optical-lattice scheme for realizing the time-reversal-invariant Hofstadter model is proposed. • The intrinsic spin Chern number related to the hybrid Wannier center in the optical lattice is investigated. • Direct measurement of the spin Chern number in the proposed system is theoretically demonstrated.

  20. Mechanisms of reversible photodegradation in disperse orange 11 dye doped in PMMA polymer

    International Nuclear Information System (INIS)

    Embaye, Natnael B.; Ramini, Shiva K.; Kuzyk, Mark G.

    2008-01-01

    We use amplified spontaneous emission (ASE) and linear absorption spectroscopy to study the mechanisms of reversible photodegradation of 1-amino-2-methylanthraquinone (disperse orange 11-DO11) in solid poly(methyl methacrylate). Measurements as a function of intensity, concentration, and time suggest that ASE originates in a state (be it a tautomer or a vibronic level) that can form a dimer or some other aggregate upon relaxation, which through fluorescence quenching leads to degradation of the ASE signal. Whatever the degradation route, a high concentration of DO11 is required and the polymer plays a key role in the process of opening a new reversible degradation pathway that is not available at lower concentrations or in liquid solutions. We construct an energy level diagram that describes all measured quantities in the decay and recovery processes and propose a hypothesis of the nature of the associated states