Lateral boundary conditions for the Klein-Gordon-Fock equation
NASA Astrophysics Data System (ADS)
Tulenov, Kanat S.; Dauitbek, Dostilek
2016-08-01
In this paper we consider an initial-boundary value problem for the Klein-Gordon-Fock equation. We prove the uniqueness of the solution and find lateral boundary conditions for the Klein-Gordon-Fock equation.
Klein-Gordon Equation in Hydrodynamical Form
Wong, Cheuk-Yin
2010-01-01
We follow and modify the Feshbach-Villars formalism by separating the Klein-Gordon equation into two coupled time-dependent Schroedinger equations for the particle and antiparticle wave functions with positive probability densities. We find that the equation of motion for the probability densities is in the form of relativistic hydrodynamics where various forces have their physical and classical counterparts. An additional element is the presence of the quantum stress tensor that depends on the derivatives of the amplitude of the wave function.
Perturbative Solutions of the Einstein Klein-Gordon Equations
NASA Astrophysics Data System (ADS)
Puliti, Gianluca; Jennings, Mara; Mamo, Vincent; Vuille, Chris
2005-11-01
As the Klein-Gordon equation is important in quantum theory and describes spin-0 particles, it is of interest to discover the nature of the gravity field such particles would be expected to create. In this paper, we solve the static, massive Einstein-Klein-Gordon (EKG) equations in perturbation, and compare the results with a similar calculation developed for the Einstein-Proca system. Subsequently, we study the massless static Klein-Gordon equation, and compare the result to the Reissner-Nordstrom metric.
Variational principles for eigenvalues of the Klein-Gordon equation
Langer, Matthias; Tretter, Christiane
2006-10-15
In this paper variational principles for eigenvalues of an abstract model of the Klein-Gordon equation with electromagnetic potential are established. They are used to characterize and estimate eigenvalues in cases where the essential spectrum has a gap around 0, even in the presence of complex eigenvalues. As a consequence, a comparison between eigenvalues of the Klein-Gordon equation in R{sup d} and eigenvalues of certain Schroedinger operators is obtained. The results are illustrated on examples including the Klein-Gordon equation with Coulomb and square-well potential.
Electromagnetic Klein-Gordon and Dirac Equations in Scale Relativity
NASA Astrophysics Data System (ADS)
Célérier, Marie-Noëlle; Nottale, Laurent
We present a new step in the foundation of quantum field theory with the tools of scale relativity. Previously, quantum motion equations (Schrödinger, Klein-Gordon, Dirac, Pauli) have been derived as geodesic equations written with a quantum-covariant derivative operator. Then, the nature of gauge transformations, of gauge fields and of conserved charges have been given a geometric meaning in terms of a scale-covariant derivative tool. Finally, the electromagnetic Klein-Gordon equation has been recovered with a covariant derivative constructed by combining the quantum-covariant velocity operator and the scale-covariant derivative. We show here that if one tries to derive the electromagnetic Dirac equation from the Klein-Gordon one as for the free particle motion, i.e. as a square root of the time part of the Klein-Gordon operator, one obtains an additional term which is the relativistic analog of the spin-magnetic field coupling term of the Pauli equation. However, if one first applies the quantum covariance, then implements the scale covariance through the scale-covariant derivative, one obtains the electromagnetic Dirac equation in its usual form. This method can also be applied successfully to the derivation of the electromagnetic Klein-Gordon equation. This suggests it rests on more profound roots of the theory, since it encompasses naturally the spin-charge coupling.
Quadratic nonlinear Klein-Gordon equation in one dimension
NASA Astrophysics Data System (ADS)
Hayashi, Nakao; Naumkin, Pavel I.
2012-10-01
We study the initial value problem for the quadratic nonlinear Klein-Gordon equation vtt + v - vxx = λv2, t ∈ R, x ∈ R, with initial conditions v(0, x) = v0(x), vt(0, x) = v1(x), x ∈ R, where v0 and v1 are real-valued functions, λ ∈ R. Using the method of normal forms of Shatah ["Normal forms and quadratic nonlinear Klein-Gordon equations," Commun. Pure Appl. Math. 38, 685-696 (1985)], we obtain a sharp asymptotic behavior of small solutions without the condition of a compact support on the initial data, which was assumed in the previous work of J.-M. Delort ["Existence globale et comportement asymptotique pour l'équation de Klein-Gordon quasi-linéaire á données petites en dimension 1," Ann. Sci. Ec. Normale Super. 34(4), 1-61 (2001)].
Klein-Gordon oscillator in Kaluza-Klein theory
NASA Astrophysics Data System (ADS)
Carvalho, Josevi; Carvalho, Alexandre M. de M.; Cavalcante, Everton; Furtado, Claudio
2016-07-01
In this contribution we study the Klein-Gordon oscillator on the curved background within the Kaluza-Klein theory. The problem of the interaction between particles coupled harmonically with topological defects in Kaluza-Klein theory is studied. We consider a series of topological defects, then we treat the Klein-Gordon oscillator coupled to this background, and we find the energy levels and corresponding eigenfunctions in these cases. We show that the energy levels depend on the global parameters characterizing these spacetimes. We also investigate a quantum particle described by the Klein-Gordon oscillator interacting with a cosmic dislocation in Som-Raychaudhuri spacetime in the presence of homogeneous magnetic field in a Kaluza-Klein theory. In this case, the energy spectrum is determined, and we observe that these energy levels represent themselves as the sum of the terms related with Aharonov-Bohm flux and of the parameter associated to the rotation of the spacetime.
Classification of integrable discrete Klein-Gordon models
NASA Astrophysics Data System (ADS)
Habibullin, Ismagil T.; Gudkova, Elena V.
2011-04-01
The Lie algebraic integrability test is applied to the problem of classification of integrable Klein-Gordon-type equations on quad graphs. The list of equations passing the test is presented, containing several well-known integrable models. A new integrable example is found; its higher symmetry is presented.
Fractional Klein-Gordon Equations and Related Stochastic Processes
NASA Astrophysics Data System (ADS)
Garra, Roberto; Orsingher, Enzo; Polito, Federico
2014-03-01
This paper presents finite-velocity random motions driven by fractional Klein-Gordon equations of order α in (0,1] . A key tool in the analysis is played by the McBride's theory which converts fractional hyper-Bessel operators into Erdélyi-Kober integral operators. Special attention is payed to the fractional telegraph process whose space-dependent distribution solves a non-homogeneous fractional Klein-Gordon equation. The distribution of the fractional telegraph process for α = 1 coincides with that of the classical telegraph process and its driving equation converts into the homogeneous Klein-Gordon equation. Fractional planar random motions at finite velocity are also investigated, the corresponding distributions obtained as well as the explicit form of the governing equations. Fractionality is reflected into the underlying random motion because in each time interval a binomial number of deviations B(n,α ) (with uniformly-distributed orientation) are considered. The parameter n of B(n,α ) is itself a random variable with fractional Poisson distribution, so that fractionality acts as a subsampling of the changes of direction. Finally the behaviour of each coordinate of the planar motion is examined and the corresponding densities obtained. Extensions to N -dimensional fractional random flights are envisaged as well as the fractional counterpart of the Euler-Poisson-Darboux equation to which our theory applies.
Extended Klein-Gordon action, gravity and nonrelativistic fluid
Hassaiene, Mokhtar
2006-03-15
We consider a scalar field action for which the Lagrangian density is a power of the massless Klein-Gordon Lagrangian. The coupling of gravity to this matter action is considered. In this case, we show the existence of nontrivial scalar field configurations with vanishing energy-momentum tensor on any static, spherically symmetric vacuum solutions of the Einstein equations. These configurations in spite of being coupled to gravity do not affect the curvature of space-time. The properties of this particular matter action are also analyzed. For a particular value of the exponent, the extended Klein-Gordon action is shown to exhibit a conformal invariance without requiring the introduction of a nonminimal coupling. We also establish a correspondence between this action and a nonrelativistic isentropic fluid in one fewer dimension. This fluid can be identified with the (generalized) Chaplygin gas for a particular value of the power. It is also shown that the nonrelativistic fluid admits, apart from the Galileo symmetry, an additional symmetry whose action is a rescaling of the time.
Numerical computation of travelling breathers in Klein Gordon chains
NASA Astrophysics Data System (ADS)
Sire, Yannick; James, Guillaume
2005-05-01
We numerically study the existence of travelling breathers in Klein-Gordon chains, which consist of one-dimensional networks of nonlinear oscillators in an anharmonic on-site potential, linearly coupled to their nearest neighbors. Travelling breathers are spatially localized solutions having the property of being exactly translated by p sites along the chain after a fixed propagation time T (these solutions generalize the concept of solitary waves for which p=1). In the case of even on-site potentials, the existence of small amplitude travelling breathers superposed on a small oscillatory tail has been proved recently [G. James, Y. Sire, Travelling breathers with exponentially small tails in a chain of nonlinear oscillators, Commun. Math. Phys., 2005, in press (available online at http://www.springerlink.com)], the tail being exponentially small with respect to the central oscillation size. In this paper, we compute these solutions numerically and continue them into the large amplitude regime for different types of even potentials. We find that Klein-Gordon chains can support highly localized travelling breather solutions superposed on an oscillatory tail. We provide examples where the tail can be made very small and is difficult to detect at the scale of central oscillations. In addition, we numerically observe the existence of these solutions in the case of non-even potentials.
Dissipative effects in nonlinear Klein-Gordon dynamics
NASA Astrophysics Data System (ADS)
Plastino, A. R.; Tsallis, C.
2016-03-01
We consider dissipation in a recently proposed nonlinear Klein-Gordon dynamics that admits exact time-dependent solutions of the power-law form e_qi(kx-wt) , involving the q-exponential function naturally arising within the nonextensive thermostatistics (e_qz \\equiv [1+(1-q)z]1/(1-q) , with e_1^z=ez ). These basic solutions behave like free particles, complying, for all values of q, with the de Broglie-Einstein relations p=\\hbar k , E=\\hbar ω and satisfying a dispersion law corresponding to the relativistic energy-momentum relation E2 = c^2p2 + m^2c4 . The dissipative effects explored here are described by an evolution equation that can be regarded as a nonlinear generalization of the celebrated telegraph equation, unifying within one single theoretical framework the nonlinear Klein-Gordon equation, a nonlinear Schrödinger equation, and the power-law diffusion (porous-media) equation. The associated dynamics exhibits physically appealing traveling solutions of the q-plane wave form with a complex frequency ω and a q-Gaussian square modulus profile.
Emergence of Compact Structures in a Klein-Gordon Model
Rosenau, Philip; Kashdan, Eugene
2010-01-22
The Klein-Gordon model (KG) squarephi=P{sup '}(|phi|)(phi/|phi|) is Lorenz invariant and has a finite wave speed, yet its localized modes, whether Q balls or vortices, suffer from the same fundamental flaw as all other solitons--they extend indefinitely. Using the KG model as a case study, we demonstrate that appending the site potential, P{sub a}(|phi|), with a subquadratic part P(|{phi}|)=b{sup 2}|{phi}|{sup 1+{delta}}+P{sub a}(|{phi}|), 0<={delta}<1, induces particlelike modes with strictly compact support. These modes are robust and shorten in the direction of motion. Their interactions, which occur only on contact, are studied in two and three dimensions and are shown to span the whole range from being nearly elastic to plastic.
Spacetimes with a separable Klein-Gordon equation in higher dimensions
NASA Astrophysics Data System (ADS)
Kolář, Ivan; Krtouš, Pavel
2016-01-01
We study spacetimes that lead to a separable Klein-Gordon equation in a general number of dimensions. We introduce an ansatz for the metric in higher dimensions motivated by analogical work by Carter in four dimensions and find solutions of the Klein-Gordon equation. For such a metric we solve the Einstein equations and regain the Kerr-NUT-(A)dS spacetime as one of our results. Other solutions lead to the Einstein-Kähler metric of a Euclidean signature. Next we investigate a warped geometry of two Klein-Gordon separable spaces with a properly chosen warped factor. We show that the resulting metric leads also to a separable Klein-Gordon equation and we find the corresponding solutions. Finally, we solve the Einstein equations for the warped geometry and obtain new solutions.
Lie group symmetries and Riemann function of Klein-Gordon-Fock equation with central symmetry
NASA Astrophysics Data System (ADS)
Kochetov, Bogdan A.
2014-06-01
In the present paper Lie symmetry group method is applied to find new exact invariant solutions for Klein-Gordon-Fock equation with central symmetry. The found invariant solutions are important for testing finite-difference computational schemes of various boundary value problems of Klein-Gordon-Fock equation with central symmetry. The classical admitted symmetries of the equation are found. The infinitesimal symmetries of the equation are used to find the Riemann function constructively.
The Klein-Gordon equation of a rotating charged hairy black hole in (2 + 1) dimensions
NASA Astrophysics Data System (ADS)
Pourhassan, B.
2016-03-01
In this paper, we consider the Klein-Gordon equation in a 3D charged rotating hairy black hole background to study behavior of a massive scalar field. In the general case, we find periodic-like behavior for the scalar field which may vanish at the black hole horizon or far from the black hole horizon. For the special cases of non-rotating or near horizon approximation, we find radial solution of Klein-Gordon equation in terms of hypergeometric and Kummer functions. Also for the case of uncharged black hole, we find numerical solution of the Klein-Gordon equation as periodic function which may enhance out of the black hole or vanish at horizon. We find allowed boundary conditions which may yield to the identical bosons described by scalar field.
Wigner function for Klein-Gordon oscillator in commutative and noncommutative spaces
NASA Astrophysics Data System (ADS)
Hassanabadi, S.; Ghominejad, M.
2016-06-01
As a quasi-probability distribution function in phase-space and a special representation of the density matrix, the Wigner function is of great significance in physics. In this work, the Wigner function for the Klein-Gordon oscillator is studied in commutative and noncommutative spaces. We first study the Wigner function for Klein-Gordon oscillator in commutative space then, by using a generalized Bopp's shift method, we obtain the corresponding Wigner function in noncommutative space. The additional terms in Wigner function on a NC space is related to the noncommutativity of space.
A Note on Exact Travelling Wave Solutions for the Klein-Gordon- Zakharov Equations
NASA Astrophysics Data System (ADS)
Zhang, Zai-Yun; Zhang, Ying-Hui; Gan, Xiang-Yang; Yu, De-Ming
2012-04-01
In this paper, we investigate the travelling wave solutions for the Klein-Gordon-Zakharov equations by using the modified trigonometric function series method benefited to the ideas of Z. Y. Zhang, Y. X. Li, Z. H. Liu, and X. J. Miao, Commun. Nonlin. Sci. Numer. Simul. , 3097 (2011). Exact travelling wave solutions are obtained
On the radius of spatial analyticity for the 1d Dirac-Klein-Gordon equations
NASA Astrophysics Data System (ADS)
Selberg, Sigmund; Tesfahun, Achenef
2015-11-01
We study the well-posedness of the Dirac-Klein-Gordon system in one space dimension with initial data that have an analytic extension to a strip around the real axis. It is proved that the radius of analyticity σ (t) of the solutions at time t cannot decay faster than 1 /t4 as | t | → ∞.
Scattering theory for the Klein-Gordon equation with nondecreasing potentials
Cruz, Maximino; Arredondo R, Juan H.
2008-11-15
The Klein-Gordon equation is considered in the case of nondecreasing potentials. The energy inner product is nonpositive on a subspace of infinite dimension, not consisting entirely of eigenvectors of the associated operator. A scattering theory for this case is developed and asymptotic completeness for generalized Moeller operators is proven.
The statistical properties of Klein-Gordon oscillator in noncommutative space
Hassanabadi, H. Hosseini, S. S.; Boumali, A.; Zarrinkamar, S.
2014-03-15
We study the relativistic spin-zero bosons influenced by the Klein-Gordon oscillator and an external magnetic field in noncommutative formulation. The problem is considered in two dimensions and is solved in an exact analytical manner. Having found the spectrum of the system, the statistical properties of an N-boson system are reported.
NASA Astrophysics Data System (ADS)
Onyeaju, M. C.; Ikot, A. N.; Chukwuocha, E. O.; Obong, H. P.; Zare, S.; Hassanabadi, H.
2016-06-01
Scattering and bound states solution for the one-dimensional Klein-Gordon particle with Hylleraas potential is presented within the frame work of position dependent effective mass formalism. We calculate in detail the reflection and transmission coefficients using the properties of hypergeometric functions and the equation of continuity of the wave functions.
Stability of Schwarzschild-AdS for the Spherically Symmetric Einstein-Klein-Gordon System
NASA Astrophysics Data System (ADS)
Holzegel, Gustav; Smulevici, Jacques
2013-01-01
In this paper, we study the global behavior of solutions to the spherically symmetric coupled Einstein-Klein-Gordon (EKG) system in the presence of a negative cosmological constant. For the Klein-Gordon mass-squared satisfying a ≥ -1 (the Breitenlohner-Freedman bound being a > -9/8), we prove that the Schwarzschild-AdS spacetimes are asymptotically stable: Small perturbations of Schwarzschild-AdS initial data again lead to regular black holes, with the metric on the black hole exterior approaching, at an exponential rate, a Schwarzschild-AdS spacetime. The main difficulties in the proof arise from the lack of monotonicity for the Hawking mass and the asymptotically AdS boundary conditions, which render even (part of) the orbital stability intricate. These issues are resolved in a bootstrap argument on the black hole exterior, with the redshift effect and weighted Hardy inequalities playing the fundamental role in the analysis. Both integrated decay and pointwise decay estimates are obtained. As a corollary of our estimates on the Klein-Gordon field, one obtains in particular exponential decay in time of spherically-symmetric solutions to the linear Klein-Gordon equation on Schwarzschild-AdS.
NASA Astrophysics Data System (ADS)
Ghafourian, M.; Hassanabadi, H.
2016-06-01
The Shannon information entropies for the Klein-Gordon equations are evaluated for the Poschl-Teller potential, and the position-space information entropies for the ground and the excited states are calculated.
Orbital instability of standing waves for the quadratic-cubic Klein-Gordon-Schrödinger system
NASA Astrophysics Data System (ADS)
Natali, Fábio; Pastor, Ademir
2015-08-01
We consider the Klein-Gordon-Schrödinger system with quadratic and cubic interactions. Smooth curves of periodic- and solitary-wave solutions are obtained via the implicit function theorem. Orbital instability of such waves is then established.
Kovalyov, Mikhail
2010-06-15
In this article the sets of solutions of the sine-Gordon equation and its linearization the Klein-Gordon equation are discussed and compared. It is shown that the set of solutions of the sine-Gordon equation possesses a richer structure which partly disappears during linearization. Just like the solutions of the Klein-Gordon equation satisfy the linear superposition principle, the solutions of the sine-Gordon equation satisfy a nonlinear superposition principle.
Effects of parity-time symmetry in nonlinear Klein-Gordon models and their stationary kinks.
Demirkaya, A; Frantzeskakis, D J; Kevrekidis, P G; Saxena, A; Stefanov, A
2013-08-01
In this work, we introduce some basic principles of PT-symmetric Klein-Gordon nonlinear field theories. By formulating a particular antisymmetric gain and loss profile, we illustrate that the stationary states of the model do not change. However, the stability critically depends on the gain and loss profile. For a symmetrically placed solitary wave (in either the continuum model or a discrete analog of the nonlinear Klein-Gordon type), there is no effect on the steady state spectrum. However, for asymmetrically placed solutions, there exists a measurable effect of which a perturbative mathematical characterization is offered. It is generally found that asymmetry towards the lossy side leads towards stability, while towards the gain side produces instability. Furthermore, a host of finite size effects, which disappear in the infinite domain limit, are illustrated in connection to the continuous spectrum of the problem. PMID:24032958
Nonlinear self-adjointness and conservation laws of Klein-Gordon-Fock equation with central symmetry
NASA Astrophysics Data System (ADS)
Abdulwahhab, Muhammad Alim
2015-05-01
The concept of nonlinear self-adjointness, introduced by Ibragimov, has significantly extends approaches to constructing conservation laws associated with symmetries since it incorporates the strict self-adjointness, the quasi self-adjointness as well as the usual linear self-adjointness. Using this concept, the nonlinear self-adjointness condition for the Klein-Gordon-Fock equation was established and subsequently used to construct simplified but infinitely many nontrivial and independent conserved vectors. The Noether's theorem was further applied to the Klein-Gordon-Fock equation to explore more distinct first integrals, result shows that conservation laws constructed through this approach are exactly the same as those obtained under strict self-adjointness of Ibragimov's method.
NASA Astrophysics Data System (ADS)
Donker, H. C.; Katsnelson, M. I.; De Raedt, H.; Michielsen, K.
2016-09-01
The logical inference approach to quantum theory, proposed earlier De Raedt et al. (2014), is considered in a relativistic setting. It is shown that the Klein-Gordon equation for a massive, charged, and spinless particle derives from the combination of the requirements that the space-time data collected by probing the particle is obtained from the most robust experiment and that on average, the classical relativistic equation of motion of a particle holds.
Klein-Gordon equations for energy-momentum of the relativistic particle in rapidity space
Yamaleev, R. M.
2013-10-15
The notion of four-rapidity is defined as a four-vector with one time-like and three space-like coordinates. It is proved, the energy and momentum defined in the space of four-rapidity obey Klein-Gordon equations constrained by the classical trajectory of a relativistic particle. It is shown, for small values of a proper mass influence of the constraint is weakened and the classical motion gains features of a wave motion.
The Einstein-Klein-Gordon Equations, Wave Dark Matter, and the Tully-Fisher Relation
NASA Astrophysics Data System (ADS)
Goetz, Andrew S.
2015-01-01
We examine the Einstein equation coupled to the Klein-Gordon equation for a complex-valued scalar field. These two equations together are known as the Einstein-Klein-Gordon system. In the low-field, non-relativistic limit, the Einstein-Klein-Gordon system reduces to the Poisson-Schrodinger system. We describe the simplest solutions of these systems in spherical symmetry, the spherically symmetric static states, and some scaling properties they obey. We also describe some approximate analytic solutions for these states. The EKG system underlies a theory of wave dark matter, also known as scalar field dark matter (SFDM), boson star dark matter, and Bose-Einstein condensate (BEC) dark matter. We discuss a possible connection between the theory of wave dark matter and the baryonic Tully-Fisher relation, which is a scaling relation observed to hold for disk galaxies in the universe across many decades in mass. We show how fixing boundary conditions at the edge of the spherically symmetric static states implies Tully-Fisher-like relations for the states. We also catalog other ``scaling conditions'' one can impose on the static states and show that they do not lead to Tully-Fisher-like relations--barring one exception which is already known and which has nothing to do with the specifics of wave dark matter.
Wave operators to a quadratic nonlinear Klein-Gordon equation in two space dimensions revisited
NASA Astrophysics Data System (ADS)
Hayashi, Nakao; Naumkin, Pavel I.; Tonegawa, Satoshi
2012-08-01
We continue to study the existence of the wave operators for the nonlinear Klein-Gordon equation with quadratic nonlinearity in two space dimensions {(partialt2-Δ+m2) u=λ u2,( t,x) in{R}×{R}2}. We prove that if u1+in{H}^{3/2+3γ,1}( {R}2),{ }u2+in{H}^{1/2+3γ,1}( {R} 2), where {γin( 0,1/4)} and the norm {Vert u1+Vert_{{H}1^{3/2+γ}}+Vert u2+Vert_{{H}1^{1/2+γ}}≤ρ,} then there exist ρ > 0 and T > 1 such that the nonlinear Klein-Gordon equation has a unique global solution {uin{C}( [ T,infty) ;{H}^{1/2}( {R}2) ) } satisfying the asymptotics Vert u( t) -u0 ( t) Vert _{{H}^{1/2}} ≤ Ct^{-1/2-γ} for all t > T, where u 0 denotes the solution of the free Klein-Gordon equation.
First Order Solutions for Klein-Gordon-Maxwell Equations in a Specific Curved Manifold Case
Murariu, Gabriel
2009-05-22
The aim of this paper is to study the SO(3,1)xU(1) gauge minimally coupled charged spinless field to a spherically symmetric curved space-time. It is derived the first order analytically approximation solution for the system of Klein-Gordon-Maxwell equations. Using these solutions, it evaluated the system electric charge density. The considered space -time manifold generalize an anterior studied one. The chosen space time configuration is of S diagonal type from the MAPLE GRTensor II metrics package.
Relativistic superfluidity and vorticity from the nonlinear Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Xiong, Chi; Good, Michael R. R.; Guo, Yulong; Liu, Xiaopei; Huang, Kerson
2014-12-01
We investigate superfluidity, and the mechanism for creation of quantized vortices, in the relativistic regime. The general framework is a nonlinear Klein-Gordon equation in curved spacetime for a complex scalar field, whose phase dynamics gives rise to superfluidity. The mechanisms discussed are local inertial forces (Coriolis and centrifugal), and current-current interaction with an external source. The primary application is to cosmology, but we also discuss the reduction to the nonrelativistic nonlinear Schrödinger equation, which is widely used in describing superfluidity and vorticity in liquid helium and cold-trapped atomic gases.
NASA Astrophysics Data System (ADS)
Koide, T.; Kodama, T.
2015-09-01
The stochastic variational method (SVM) is the generalization of the variational approach to systems described by stochastic variables. In this paper, we investigate the applicability of SVM as an alternative field-quantization scheme, by considering the complex Klein-Gordon equation. There, the Euler-Lagrangian equation for the stochastic field variables leads to the functional Schrödinger equation, which can be interpreted as the Euler (ideal fluid) equation in the functional space. The present formulation is a quantization scheme based on commutable variables, so that there appears no ambiguity associated with the ordering of operators, e.g., in the definition of Noether charges.
Analytical solution of the Klein Gordon equation for a quadratic exponential-type potential
NASA Astrophysics Data System (ADS)
Ezzatpour, Somayyeh; Akbarieh, Amin Rezaei
2016-07-01
In this research study, analytical solutions of the Klein Gordon equation by considering the potential as a quadratic exponential will be presented. However, the potential is assumed to be within the framework of an approximation for the centrifugal potential in any state. The Nikiforov-Uvarov method is used to calculate the wave function, as well as corresponding exact energy equation, in bound states. We finally concluded that the quadratic exponential-type potential under which the results were deduced, led to outcomes that were comparable to the results obtained from the well-known potentials in some special cases.
Efficient and accurate numerical methods for the Klein-Gordon-Schroedinger equations
Bao, Weizhu . E-mail: bao@math.nus.edu.sg; Yang, Li . E-mail: yangli@nus.edu.sg
2007-08-10
In this paper, we present efficient, unconditionally stable and accurate numerical methods for approximations of the Klein-Gordon-Schroedinger (KGS) equations with/without damping terms. The key features of our methods are based on: (i) the application of a time-splitting spectral discretization for a Schroedinger-type equation in KGS (ii) the utilization of Fourier pseudospectral discretization for spatial derivatives in the Klein-Gordon equation in KGS (iii) the adoption of solving the ordinary differential equations (ODEs) in phase space analytically under appropriate chosen transmission conditions between different time intervals or applying Crank-Nicolson/leap-frog for linear/nonlinear terms for time derivatives. The numerical methods are either explicit or implicit but can be solved explicitly, unconditionally stable, and of spectral accuracy in space and second-order accuracy in time. Moreover, they are time reversible and time transverse invariant when there is no damping terms in KGS, conserve (or keep the same decay rate of) the wave energy as that in KGS without (or with a linear) damping term, keep the same dynamics of the mean value of the meson field, and give exact results for the plane-wave solution. Extensive numerical tests are presented to confirm the above properties of our numerical methods for KGS. Finally, the methods are applied to study solitary-wave collisions in one dimension (1D), as well as dynamics of a 2D problem in KGS.
NASA Astrophysics Data System (ADS)
Konkowski, Deborah A.; Arndt, Valerie; Helliwell, Thomas M.
2002-04-01
Klein-Gordon, Maxwell and Dirac fields are studied in quasiregular spacetimes, spacetimes with a classical quasiregular singularity, the mildest true classical singularity [G.F.R. Ellis and B.G. Schmidt, Gen. Rel. Grav.8, 915 (1977)]. A class of static quasiregular spacetimes possessing disclinations and dislocations [R.A. Puntigam and H.H. Soleng, Class. Quantum Grav. 14, 1129 (1997)] is shown to have field operators which are not essentially self-adjoint. This class of spacetimes includes an idealized cosmic string, i.e., a four-dimensional spacetime with a conical singularity [L.H. Ford and A. Vilenkin, J. Phys. A: Math. Gen. 14, 2353 (1981)], and a Galtsov/Letelier/Tod spacetime featuring a screw dislocation [K.P. Tod, Class. Quantum Grav. 11, 1331 (1994); D.V. Galtsov and P.S. Letelier, Phys. Rev. D47, 4273 (1993)]. The definition of G. T. Horowitz and D. Marolf [Phys. Rev. D52, 5670 (1995)] for a quantum-mechanically singular spacetime as one in which the spatial-derivative operator in the Klein-Gordon equation for a massive scalar field is not essentially self-adjoint is extended in the case of quasiregular spacetimes to include Maxwell and Dirac fields. Therefore, the class of static quasiregular spacetimes under consideration is quantum-mechanically singular independent of the type of test field.
NASA Astrophysics Data System (ADS)
Villalba, Víctor M.; Catalá, Esteban Isasi
2002-10-01
We solve the Klein-Gordon and Dirac equations in an open cosmological universe with a partially horn topology in the presence of a time dependent magnetic field. Since the exact solution cannot be obtained explicitly for arbitrary time dependence of the field, we discuss the asymptotic behavior of the solutions with the help of the relativistic Hamilton-Jacobi equation.
NASA Astrophysics Data System (ADS)
Ita, B. I.; Obong, H. P.; Ehi-Eromosele, C. O.; Edobor-Osoh, A.; Ikeuba, A. I.
2014-11-01
The solutions of the Klein-Gordon equation with equal scalar and vector harmonic oscillator plus inverse quadratic potential for S-waves have been presented using the Nikiforov-Uvarov method. The bound state energy eigenvalues and the corresponding un-normalized eigenfunctions are obtained in terms of the Laguerre polynomials.
NASA Astrophysics Data System (ADS)
Nakanishi, K.; Schlag, W.
2012-03-01
We extend our result Nakanishi and Schlag in J. Differ. Equ. 250(5):2299-2333, 2011) to the non-radial case, giving a complete classification of global dynamics of all solutions with energy that is at most slightly above that of the ground state for the nonlinear Klein-Gordon equation with the focusing cubic nonlinearity in three space dimensions.
Eab, C. H.; Lim, S. C.; Teo, L. P.
2007-08-15
This paper studies the Casimir effect due to fractional massless Klein-Gordon field confined to parallel plates. A new kind of boundary condition called fractional Neumann condition which involves vanishing fractional derivatives of the field is introduced. The fractional Neumann condition allows the interpolation of Dirichlet and Neumann conditions imposed on the two plates. There exists a transition value in the difference between the orders of the fractional Neumann conditions for which the Casimir force changes from attractive to repulsive. Low and high temperature limits of Casimir energy and pressure are obtained. For sufficiently high temperature, these quantities are dominated by terms independent of the boundary conditions. Finally, validity of the temperature inversion symmetry for various boundary conditions is discussed.
Klein-Gordon equation and reflection of Alfven waves in nonuniform media
NASA Technical Reports Server (NTRS)
Musielak, Z. E.; Fontenla, J. M.; Moore, R. L.
1992-01-01
A new analytical approach is presented for assessing the reflection of linear Alfven waves in smoothly nonuniform media. The general one-dimensional case in Cartesian coordinates is treated. It is shown that the wave equations, upon transformation into the form of the Klein-Gordon equation, display a local critical frequency for reflection. At any location in the medium, reflection becomes strong as the wave frequency descends past this characteristic frequency set by the local nonuniformity of the medium. This critical frequecy is given by the transformation as an explicit function of the Alfven velocity and its first and second derivatives, and hence as an explicit spatial function. The transformation thus directly yields, without solution of the wave equations, the location in the medium at which an Alfven wave of any given frequency becomes strongly reflected and has its propagation practically cut off.
Sharp comparison theorems for the Klein-Gordon equation in d dimensions
NASA Astrophysics Data System (ADS)
Hall, Richard L.; Zorin, Petr
2016-06-01
We establish sharp (or ’refined’) comparison theorems for the Klein-Gordon equation. We show that the condition Va ≤ Vb, which leads to Ea ≤ Eb, can be replaced by the weaker assumption Ua ≤ Ub which still implies the spectral ordering Ea ≤ Eb. In the simplest case, for d = 1, Ui(x) =∫0xV i(t)dt, i = a or b and for d > 1, Ui(r) =∫0rV i(t)td‑1dt, i = a or b. We also consider sharp comparison theorems in the presence of a scalar potential S (a ‘variable mass’) in addition to the vector term V (the time component of a four-vector). The theorems are illustrated by a variety of explicit detailed examples.
Dynamical Hamiltonian-Hopf instabilities of periodic traveling waves in Klein-Gordon equations
NASA Astrophysics Data System (ADS)
Marangell, R.; Miller, P. D.
2015-07-01
We study the unstable spectrum close to the imaginary axis for the linearization of the nonlinear Klein-Gordon equation about a periodic traveling wave in a co-moving frame. We define dynamical Hamiltonian-Hopf instabilities as points in the stable spectrum that are accumulation points for unstable spectrum, and show how they can be determined from the knowledge of the discriminant of Hill's equation for an associated periodic potential. This result allows us to give simple criteria for the existence of dynamical Hamiltonian-Hopf instabilities in terms of instability indices previously shown to be useful in stability analysis of periodic traveling waves. We also discuss how these methods can be applied to more general nonlinear wave equations.
Klein-Gordon Solutions on Non-Globally Hyperbolic Standard Static Spacetimes
NASA Astrophysics Data System (ADS)
Bullock, David M. A.
2012-11-01
We construct a class of solutions to the Cauchy problem of the Klein-Gordon equation on any standard static spacetime. Specifically, we have constructed solutions to the Cauchy problem based on any self-adjoint extension (satisfying a technical condition: "acceptability") of (some variant of) the Laplace-Beltrami operator defined on test functions in an L2-space of the static hypersurface. The proof of the existence of this construction completes and extends work originally done by Wald. Further results include: the uniqueness of these solutions; their support properties; the construction of the space of solutions and the energy and symplectic form on this space; an analysis of certain symmetries on the space of solutions; and various examples of this method, including the construction of a non-bounded below acceptable self-adjoint extension generating the dynamics.
Didactic derivation of the special theory of relativity from the Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Arodź, H.
2014-09-01
We present a didactic derivation of the special theory of relativity in which Lorentz transformations are ‘discovered’ as symmetry transformations of the Klein-Gordon equation. The interpretation of Lorentz boosts as transformations to moving inertial reference frames is not assumed at the start, but it naturally appears at a later stage. The relative velocity v of two inertial reference frames is defined in terms of the elements of the pertinent Lorentz matrix, and the bound |{\\bf v}| is presented as a simple theorem that follows from the structure of the Lorentz group. The polar decomposition of Lorentz matrices is used to explain noncommutativity and nonassociativity of the relativistic composition (‘addition’) of velocities.
NASA Astrophysics Data System (ADS)
Wu, Xinyuan; Liu, Changying
2016-02-01
In this paper, we are concerned with the initial boundary value problem of arbitrarily high-dimensional Klein-Gordon equations, posed on a bounded domain Ω ⊂ ℝd for d ≥ 1 and equipped with the requirement of boundary conditions. We derive and analyze an integral formula which is proved to be adapted to different boundary conditions for general Klein-Gordon equations in arbitrarily high-dimensional spaces. The formula gives a closed-form solution to arbitrarily high-dimensional homogeneous linear Klein-Gordon equations, which is totally different from the well-known D'Alembert, Poisson, and Kirchhoff formulas. Some applications are included as well.
NASA Astrophysics Data System (ADS)
Nakao, Mitsuhiro
We prove the existence of global decaying solutions to the exterior problem for the Klein-Gordon equation with a nonlinear localized dissipation and a derivative nonlinearity. To derive the required estimates of solutions we employ a 'loan' method.
NASA Astrophysics Data System (ADS)
Vitória, R. L. L.; Furtado, C.; Bakke, K.
2016-07-01
The relativistic quantum dynamics of an electrically charged particle subject to the Klein-Gordon oscillator and the Coulomb potential is investigated. By searching for relativistic bound states, a particular quantum effect can be observed: a dependence of the angular frequency of the Klein-Gordon oscillator on the quantum numbers of the system. The meaning of this behaviour of the angular frequency is that only some specific values of the angular frequency of the Klein-Gordon oscillator are permitted in order to obtain bound state solutions. As an example, we obtain both the angular frequency and the energy level associated with the ground state of the relativistic system. Further, we analyse the behaviour of a relativistic position-dependent mass particle subject to the Klein-Gordon oscillator and the Coulomb potential.
NASA Astrophysics Data System (ADS)
Ikot, A. N.; Obong, H. P.; Abbey, T. M.; Zare, S.; Ghafourian, M.; Hassanabadi, H.
2016-05-01
In this article we use supersymmetry quantum mechanics and factorization methods to study the bound and scattering state of Klein-Gordon equation with deformed Hulthen plus deformed hyperbolical potential for arbitrary state in D-dimensions. The analytic relativistic bound state eigenvalues and the scattering phase factor are found in closed form. We report on the numerical results for the bound state energy in D-dimensions.
NASA Astrophysics Data System (ADS)
Mu, Xiyu; Cheng, Hao; Liu, Guoqing
2016-04-01
It is often difficult to provide the exact boundary condition in the practical use of variational method. The Euler equation derived from variational method cannot be solved without boundary condition. However, in some application problems such as the assimilation of remote sensing data, the values can be easily obtained in the inner region of the domain. Since the solution of elliptic partial differential equations continuously depends on the boundary condition, the boundary condition can be retrieved using part solutions in the inner area. In this paper, the variational problem of remote sensing data assimilation within a circular area is first established. The Klein-Gordon elliptic equation is derived from the Euler method of variational problems with assumed boundary condition. Secondly, a computer-friendly Green function is constructed for the Dirichlet problem of two-dimensional Klein-Gordon equation, with the formal solution according to Green formula. Thirdly, boundary values are retrieved by solving the optimal problem which is constructed according to the smoothness of boundary value function and the best approximation between formal solutions and high-accuracy measurements in the interior of the domain. Finally, the assimilation problem is solved on substituting the retrieved boundary values into the Klein-Gordon equation. It is a type of inverse problem in mathematics. The advantage of our method lies in that it needs no assumptions of the boundary condition. It thus alleviates the error introduced by artificial boundary condition in data fusion using variational method in the past.
A local energy-preserving scheme for Klein-Gordon-Schrödinger equations
NASA Astrophysics Data System (ADS)
Cai, Jia-Xiang; Wang, Jia-Lin; Wang, Yu-Shun
2015-05-01
A local energy conservation law is proposed for the Klein-Gordon-Schrödinger equations, which is held in any local time-space region. The local property is independent of the boundary condition and more essential than the global energy conservation law. To develop a numerical method preserving the intrinsic properties as much as possible, we propose a local energy-preserving (LEP) scheme for the equations. The merit of the proposed scheme is that the local energy conservation law can hold exactly in any time-space region. With the periodic boundary conditions, the scheme also possesses the discrete change and global energy conservation laws. A nonlinear analysis shows that the LEP scheme converges to the exact solutions with order 𝒪(τ2 + h2). The theoretical properties are verified by numerical experiments. Project supported by the National Natural Science Foundation of China (Grant Nos. 11201169, 11271195, and 41231173) and the Project of Graduate Education Innovation of Jiangsu Province, China (Grant No. CXLX13 366).
Critical and noncritical long-range entanglement in Klein-Gordon fields
Marcovitch, S.; Reznik, B.; Retzker, A.; Plenio, M. B.
2009-07-15
We investigate the entanglement between two spatially separated intervals in the vacuum state of a free one-dimensional Klein-Gordon field by means of explicit computations in the continuum limit of the linear harmonic chain. We demonstrate that the entanglement, which we quantify by the logarithmic negativity, is finite with no further need for renormalization. We find that in the critical regime, the quantum correlations are scale invariant as they depend only on the ratio of distance to length. They decay much faster than the classical correlations as in the critical limit long-range entanglement decays exponentially for separations larger than the size of the blocks, while classical correlations follow a power-law decay. With decreasing distance of the blocks, the entanglement diverges as a power law in the distance. The noncritical regime manifests richer behavior, as the entanglement depends both on the size of the blocks and on their separation. In correspondence with the von Neumann entropy also long-range entanglement distinguishes critical from noncritical systems.
Hunting the ghosts of a 'strictly quantum field': the Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Bertozzi, Eugenio
2010-11-01
This paper aims to identify and tackle some problems related to teaching quantum field theory (QFT) at university level. In particular, problems arising from the canonical quantization are addressed by focusing on the Klein-Gordon equation (KGE). After a brief description of the status of the KGE in teaching as it emerges from an analysis of a selected sample of university textbooks, an analysis of the applications of the KGE in contexts different from the QFT is presented. The results of the analysis show that, while in the real case the solutions of the equation can be easily interpreted from a physical point of view, in the complex case the coherence with relativistic quantum mechanics and the electrodynamics framework brings to light interpretative problems related to the classical complex KG field. The comparison between the classical cases investigated and the QFT framework, where the equation finds a coherent particle interpretation, leads to share Ryder's statement asserting that the KG field is a 'strictly quantum field'. Implications of the results in terms of remarks about the canonical procedure currently utilized for teaching are underlined.
Hydromagnetic waves in a compressed-dipole field via field-aligned Klein-Gordon equations
NASA Astrophysics Data System (ADS)
Zheng, Jinlei; Hu, Qiang; Webb, Gary M.; McKenzie, James F.
2016-05-01
Hydromagnetic waves, especially those of frequencies in the range of a few millihertz to a few hertz observed in the Earth's magnetosphere, are categorized as ultra low-frequency (ULF) waves or pulsations. They have been extensively studied due to their importance in the interaction with radiation belt particles and in probing the structures of the magnetosphere. We developed an approach to examining the toroidal standing Aflvén waves in a background magnetic field by recasting the wave equation into a Klein-Gordon (KG) form along individual field lines. The eigenvalue solutions to the system are characteristic of a propagation type when the corresponding eigenfrequency is greater than a critical frequency and a decaying type otherwise. We apply the approach to a compressed-dipole magnetic field model of the inner magnetosphere and obtain the spatial profiles of relevant parameters and the spatial wave forms of harmonic oscillations. We further extend the approach to poloidal-mode standing Alfvén waves along field lines. In particular, we present a quantitative comparison with a recent spacecraft observation of a poloidal standing Alfvén wave in the Earth's magnetosphere. Our analysis based on the KG equation yields consistent results which agree with the spacecraft measurements of the wave period and the amplitude ratio between the magnetic field and electric field perturbations.
Quantum breathers in Klein-Gordon lattice: Non-periodic boundary condition approach
NASA Astrophysics Data System (ADS)
Mandal, Subhra Jyoti; Choudhary, Kamal; Biswas, Arindam; Bandyopadhyay, A. K.; Bhattacharjee, A. K.; Mandal, D.
2011-12-01
The presence of classical breathers and two-phonon bound state (TPBS) or quantum breather (QB) state through detailed quantum calculations have already been shown in technologically important ferroelectric materials, such as lithium niobate with antisite niobium charge defects concerning pinning transition, its control, and application. The latter was done in a periodic boundary condition with Bloch function in terms of significant variations of TPBS parameters against impurity, which is related to nonlinearity. In further extension of this work, in a non-periodic boundary condition and number-conserving approach, apart from various techniques available, only the temporal evolution of the number of quanta (i.e., phonons) in more sites is detailed in this present investigation for a generalized Klein-Gordon system with applications in ferroelectrics, metamaterials, and DNA. The critical time of redistribution of quanta that is proportional to the QB's lifetime in these materials shows different types of behavior in the femtosecond range, which gives rise to the possibilities for making various devices.
Solitons and chaos of the Klein-Gordon-Zakharov system in a high-frequency plasma
NASA Astrophysics Data System (ADS)
Zhen, Hui-Ling; Tian, Bo; Sun, Ya; Chai, Jun; Wen, Xiao-Yong
2015-10-01
In this paper, we study the Klein-Gordon-Zakharov (KGZ) system, which describes the interaction between the Langmuir wave and ion sound wave in a high-frequency plasma. By means of the Hirota method and symbolic computation, bright and mixed-type soliton solutions are obtained. For the one soliton, amplitude of E is positively related to β 2 , and that of n is inversely related to β 2 , while they are both positively related to α, where E refers to the high-frequency part of the electrostatic potential of the electric field raised by the electrons, and n represents the deviation of ion density from its equilibrium, β 2 and α are the plasma frequency and ion sound speed, respectively. Head-on interactions between the two bright solitons and two mixed-type ones are respectively displayed. With β 2 increasing, the head-on interaction is transformed into an overtaking one. Bright bound-state solitons are investigated, and the interaction period decreases with α increasing. Furthermore, with the external forces Γ 1 ( t ) and Γ 2 ( t ) introduced, the perturbed KGZ system is studied numerically for its associated chaotic motions. Both the weak and developed chaotic motions can be observed. Γ 1 ( t ) and Γ 2 ( t ) have different effects on the chaotic motions: the chaotic motion can be weakened by decreasing the amplitude of Γ 1 ( t ) or increasing the amplitude and frequency of Γ 2 ( t ) .
Generalized and functional separable solutions to nonlinear delay Klein-Gordon equations
NASA Astrophysics Data System (ADS)
Polyanin, Andrei D.; Zhurov, Alexei I.
2014-08-01
We describe a number of generalized separable, functional separable, and some other exact solutions to nonlinear delay Klein-Gordon equations of the formutt=kuxx+F(u,w), where u=u(x,t) and w=u(x,t-τ), with τ denoting the delay time. The generalized separable solutions are sought in the form u=∑n=1NΦn(x)Ψn(t), where the functions Φn(x) and Ψn(t) are to be determined subsequently. Most of the equations considered contain one or two arbitrary functions of a single argument or one arbitrary function of two arguments of special form. We present a substantial number of new exact solutions, including periodic and antiperiodic ones, as well as composite solutions resulting from a nonlinear superposition of generalized separable and traveling wave solutions. All solutions involve free parameters (in some cases, infinitely many) and so can be suitable for solving certain problems and testing approximate analytical and numerical methods for nonlinear delay PDEs.
Huygens' principle for the Klein-Gordon equation in the de Sitter spacetime
Yagdjian, Karen
2013-09-15
In this article we prove that the Klein-Gordon equation in the de Sitter spacetime obeys the Huygens' principle only if the physical mass m of the scalar field and the dimension n⩾ 2 of the spatial variable are tied by the equation m{sup 2}= (n{sup 2}−1)/4. Moreover, we define the incomplete Huygens' principle, which is the Huygens' principle restricted to the vanishing second initial datum, and then reveals that the massless scalar field in the de Sitter spacetime obeys the incomplete Huygens' principle and does not obey the Huygens' principle, for the dimensions n= 1, 3, only. Thus, in the de Sitter spacetime the existence of two different scalar fields (in fact, with m= 0 and m{sup 2}= (n{sup 2}−1)/4), which obey incomplete Huygens' principle, is equivalent to the condition n= 3, the spatial dimension of the physical world. In fact, Paul Ehrenfest in 1917 addressed the question: “Why has our space just three dimensions?”. For n= 3 these two values of the mass are the endpoints of the so-called in quantum field theory the Higuchi bound. The value m{sup 2}= (n{sup 2}−1)/4 of the physical mass allows us also to obtain complete asymptotic expansion of the solution for the large time.
Gromov, E.M.; Talanov, V.I.
1992-01-01
Questions relating to the penetration of fields into supercritical regions of inhomogeneous media are of considerable interest both for fundamental studies in wave theory and for applied problems in various areas of physics. In strong fields this penetration is related to nonlinear restructuring of the parameters of the medium under the action of the field itself. In weak fields penetration is possible when a strong wave in the parameters of the medium is present and are facilitated if the dynamic states undergo frequency shifts in the inhomogeneous medium in the presence of this wave. Such states have been quite well studied for fields described by equations such as the Schroedinger equation. At the same time it was noted that dynamic field states can exist which are described by the Klein-Gordon equation. In the present work we study the dynamic states of such fields in the presence of a parameter wave. We point out the possibility of entraining packets of the field by this wave. The efficiency with which these entrained states are excited is determined for a parameter wave in the form of a discontinuous shock. 12 refs.
NASA Astrophysics Data System (ADS)
LeFloch, Philippe G.; Ma, Yue
2016-01-01
The Hyperboloidal Foliation Method (introduced by the authors in 2014) is extended here and applied to the Einstein equations of general relativity. Specifically, we establish the nonlinear stability of Minkowski spacetime for self-gravitating massive scalar fields, while existing methods only apply to massless scalar fields. First of all, by analyzing the structure of the Einstein equations in wave coordinates, we exhibit a nonlinear wave-Klein-Gordon model defined on a curved background, which is the focus of the present paper. For this model, we prove here the existence of global-in-time solutions to the Cauchy problem, when the initial data have sufficiently small Sobolev norms. A major difficulty comes from the fact that the class of conformal Killing fields of Minkowski space is significantly reduced in the presence of a massive scalar field, since the scaling vector field is not conformal Killing for the Klein-Gordon operator. Our method relies on the foliation (of the interior of the light cone) of Minkowski spacetime by hyperboloidal hypersurfaces and uses Lorentz-invariant energy norms. We introduce a frame of vector fields adapted to the hyperboloidal foliation and we establish several key properties: Sobolev and Hardy-type inequalities on hyperboloids, as well as sup-norm estimates, which correspond to the sharp time decay for the wave and the Klein-Gordon equations. These estimates allow us to control interaction terms associated with the curved geometry and the massive field by distinguishing between two levels of regularity and energy growth and by a successive use of our key estimates in order to close a bootstrap argument.
NASA Astrophysics Data System (ADS)
Xu, Xiao-Ge; Gao, Yi-Tian; Wei, Guang-Mei
In this paper, the nonlinear Klein-Gordon equation describing the propagation of pulse waves in plasma or waveguide is investigated. With symbolic computation, the generalized Bäcklund Transformations (BTs) for this equation are constructed under different conditions. It is shown that the BTs published in the previous literature for the Sine-Gordon equation, Sinh-Gordon equation, and Liouville equation all turn out to be special cases of the results in the present paper. Moreover, the corresponding Lax pairs are explicitly derived from the obtained BTs through some transformations.
NASA Astrophysics Data System (ADS)
Alonso-Mallo, I.; Portillo, A. M.
2016-04-01
Klein-Gordon equations on an unbounded domain are considered in one dimensional and two dimensional cases. Numerical computation is reduced to a finite domain by using the Hagstrom-Warburton (H-W) high-order absorbing boundary conditions (ABCs). Time integration is made by means of exponential splitting schemes that are efficient and easy to implement. In this way, it is possible to achieve a negligible error due to the time integration and to study the behavior of the absorption error. Numerical experiments displaying the accuracy of the numerical solution for the two dimensional case are provided. The influence of the dispersion coefficient on the error is also studied.
NASA Astrophysics Data System (ADS)
Saha Ray, S.; Sahoo, S.
2016-07-01
In this paper, homotopy perturbation transform method and modified homotopy analysis method have been applied to obtain the approximate solutions of the time fractional coupled Klein-Gordon-Zakharov equations. We consider fractional coupled Klein-Gordon-Zakharov equation with appropriate initial values using homotopy perturbation transform method and modified homotopy analysis method. Here we obtain the solution of fractional coupled Klein-Gordon-Zakharov equation, which is obtained by replacing the time derivatives with a fractional derivatives of order α ∈ (1, 2], β ∈ (1, 2]. Through error analysis and numerical simulation, we have compared approximate solutions obtained by two present methods homotopy perturbation transform method and modified homotopy analysis method. The fractional derivatives here are described in Caputo sense.
NASA Astrophysics Data System (ADS)
Suárez, Abril; Chavanis, Pierre-Henri
2015-07-01
Using a generalization of the Madelung transformation, we derive the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit. We consider a complex self-interacting scalar field with a λ |φ |4 potential. We study the evolution of the spatially homogeneous background in the fluid representation and derive the linearized equations describing the evolution of small perturbations in a static and in an expanding Universe. We compare the results with simplified models in which the gravitational potential is introduced by hand in the Klein-Gordon equation, and assumed to satisfy a (generalized) Poisson equation. Nonrelativistic hydrodynamic equations based on the Schrödinger-Poisson equations or on the Gross-Pitaevskii-Poisson equations are recovered in the limit c →+∞. We study the evolution of the perturbations in the matter era using the nonrelativistic limit of our formalism. Perturbations whose wavelength is below the Jeans length oscillate in time while perturbations whose wavelength is above the Jeans length grow linearly with the scale factor as in the cold dark matter model. The growth of perturbations in the scalar field model is substantially faster than in the cold dark matter model. When the wavelength of the perturbations approaches the cosmological horizon (Hubble length), a relativistic treatment is mandatory. In that case, we find that relativistic effects attenuate or even prevent the growth of perturbations. This paper exposes the general formalism and provides illustrations in simple cases. Other applications of our formalism will be considered in companion papers.
NASA Astrophysics Data System (ADS)
Hack, Thomas-Paul
2014-11-01
We quantize the linearized Einstein-Klein-Gordon system on arbitrary on-shell backgrounds in a manifestly covariant and gauge-invariant manner. For the special case of perturbations in inflation, i.e. on-shell backgrounds of Friedmann-Lemaître-Robertson-Walker type, we compare our general quantization construction with the standard approach to the quantum theory of perturbations in inflation. We find that not all local quantum observables of the linearized Einstein-Klein-Gordon system can be split into local observables of scalar and tensor type as in the standard approach. However, we argue that this subclass of observables is sufficient for measuring perturbations that vanish at spatial infinity, which is in line with standard assumptions. Finally, we comment on a recent observation that, upon standard quantization, the quantum Bardeen potentials display a non-local behaviour and argue that a similar phenomenon occurs in any local quantum field theory. It is the hope of the author that the present work may constitute a bridge between the generally applicable and thus powerful framework of algebraic quantum field theory in curved spacetimes and the standard treatment of perturbations in inflation.
Numerical Studies of Nonlinear Schrodinger and Klein-Gordon Systems: Techniques and Applications
NASA Astrophysics Data System (ADS)
Choi, Dae-Il
The continuing proliferation of computational resources makes it more and more powerful to conduct numerical studies on physics problems for which either analytic methods fail, or well-controlled experiments are very difficult, if not impossible. In particular, a finite-difference based numerical approach. has been an indispensable tool in the three areas of physics that, I study in this thesis: numerical relativity (boson stars), Bose-Einstein condensates, and atomic hydrogen in strong laser fields. Numerical relativity (NR) enables us to tackle problems of astrophysical interest which are difficult or impossible to study using analytic methods. Many of these problems involve strong and dynamical gravitational fields, and many involve the dynamics of one or more gravitationally compact objects such as black holes, neutron stars or, more speculatively, boson stars. A long term goal of NR, then (and of this research) is the accurate simulation of the dynamics of one or more compact objects. Here, as a step in that direction, I present some of the first results for a fully coupled Einstein/Klein-Gordon system in 3D, wherein I attempt to evolve a static relativistic boson star using the full equations of motion. A key motivation for the study of self-gravitating bosonic matter (in both the Newtonian and Einsteinian regimes) is the observation that, even though any direct physical relevance has yet to be demonstrated, boson star systems provide excellent numerical laboratories in which to develop techniques for NR. Specifically, the boson star model provides an ideal vehicle with which to implement and evaluate (1) various coordinate conditions in the context of the ADM formalism and (2) multidimensional adaptive mesh refinement techniques which appear crucial for many problems in 3D numerical relativity. Again, as a step towards studying the fully relativistic problem, I first consider boson stars in the Newtonian regime, which are described by the solutions of Schr
NASA Astrophysics Data System (ADS)
Sergyeyev, Artur; Krtouš, Pavel
2008-02-01
We consider the Klein-Gordon equation in generalized higher-dimensional Kerr-NUT-(A)dS spacetime without imposing any restrictions on the functional parameters characterizing the metric. We establish commutativity of the second-order operators constructed from the Killing tensors found in [J. High Energy Phys.JHEPFG1029-8479 02 (2007) 00410.1088/1126-6708/2007/02/004] and show that these operators, along with the first-order operators originating from the Killing vectors, form a complete set of commuting symmetry operators (i.e., integrals of motion) for the Klein-Gordon equation. Moreover, we demonstrate that the separated solutions of the Klein-Gordon equation obtained in [J. High Energy Phys.JHEPFG1029-8479 02 (2007) 00510.1088/1126-6708/2007/02/005] are joint eigenfunctions for all of these operators. We also present an explicit form of the zero mode for the Klein-Gordon equation with zero mass. In the semiclassical approximation we find that the separated solutions of the Hamilton-Jacobi equation for geodesic motion are also solutions for a set of Hamilton-Jacobi-type equations which correspond to the quadratic conserved quantities arising from the above Killing tensors.
Sergyeyev, Artur; Krtous, Pavel
2008-02-15
We consider the Klein-Gordon equation in generalized higher-dimensional Kerr-NUT-(A)dS spacetime without imposing any restrictions on the functional parameters characterizing the metric. We establish commutativity of the second-order operators constructed from the Killing tensors found in [J. High Energy Phys. 02 (2007) 004] and show that these operators, along with the first-order operators originating from the Killing vectors, form a complete set of commuting symmetry operators (i.e., integrals of motion) for the Klein-Gordon equation. Moreover, we demonstrate that the separated solutions of the Klein-Gordon equation obtained in [J. High Energy Phys. 02 (2007) 005] are joint eigenfunctions for all of these operators. We also present an explicit form of the zero mode for the Klein-Gordon equation with zero mass. In the semiclassical approximation we find that the separated solutions of the Hamilton-Jacobi equation for geodesic motion are also solutions for a set of Hamilton-Jacobi-type equations which correspond to the quadratic conserved quantities arising from the above Killing tensors.
NASA Astrophysics Data System (ADS)
Tang, Bing; Li, De-Jun
2016-05-01
A theoretical work on quantum breathers in a nonlinear Klein-Gordon lattice model with nearest and next-nearest neighbor interactions is presented. The semiclassical and the full quantum cases are respectively considered. For the semiclassical case, we obtain the analytical solution of discrete breather, and find that the wave number corresponding to the appearance of discrete breather changes when the ratio of the next-nearest- to -nearest - neighbor harmonic force constants is greater than 1/4. For the full quantum case, by calculating the energy spectrum of the system containing two quanta, we prove numerically the existence of quantum breathers (two-quanta bound states) and find the shape of energy spectrum changes dramatically as the value of next -nearest neighbor harmonic force constant increasing.
NASA Astrophysics Data System (ADS)
Babin, Anatoli; Figotin, Alexander
2013-09-01
Einstein's relation E = Mc 2 between the energy E and the mass M is the cornerstone of the relativity theory. This relation is often derived in a context of the relativistic theory for closed systems which do not accelerate. By contrast, the Newtonian approach to the mass is based on an accelerated motion. We study here a particular neoclassical field model of a particle governed by a nonlinear Klein-Gordon (KG) field equation. We prove that if a solution to the nonlinear KG equation and its energy density concentrate at a trajectory, then this trajectory and the energy must satisfy the relativistic version of Newton's law with the mass satisfying Einstein's relation. Therefore the internal energy of a localized wave affects its acceleration in an external field as the inertial mass does in Newtonian mechanics. We demonstrate that the "concentration" assumptions hold for a wide class of rectilinear accelerating motions.
NASA Astrophysics Data System (ADS)
Vigier, Jean-Pierre
1991-02-01
Starting from a nonlinear relativistic Klein-Gordon equation derived from the stochastic interpretation of quantum mechanics (proposed by Bohm-Vigier, (1) Nelson, (2) de Broglie, (3) Guerra et al. (4) ), one can construct joint wave and particle, soliton-like solutions, which follow the average de Broglie-Bohm (5) real trajectories associated with linear solutions of the usual Schrödinger and Klein-Gordon equations.
NASA Astrophysics Data System (ADS)
Pesci, Adriana I.; Goldstein, Raymond E.; Uys, Hermann
2005-05-01
In previous work we have shown that the quantum potential can be derived from the classical kinetic equations both for particles with and without spin. Here, we extend these mappings to the relativistic case. The essence of the analysis consists of Fourier transforming the momentum coordinate of the distribution function. This procedure introduces a natural parameter η with units of angular momentum. In the non-relativistic case the ansatz of either separability, or separability and additivity, imposed on the probability distribution function produces mappings onto the Schrödinger equation and the Pauli equation, respectively. The former corresponds to an irrotational flow, the latter to a fluid with non-zero vorticity. In this work we show that the relativistic mappings lead to the Klein-Gordon equation in the irrotational case and to the second-order Dirac equation in the rotational case. These mappings are irreversible; an approximate inverse is the Wigner function. Taken together, these results provide a statistical interpretation of quantum mechanics.
Complex structures for an S-matrix of Klein-Gordon theory on AdS spacetimes
NASA Astrophysics Data System (ADS)
Dohse, Max; Oeckl, Robert
2015-05-01
While the standard construction of the S-matrix fails on anti-de Sitter (AdS) spacetime, a generalized S-matrix makes sense, based on the hypercylinder geometry induced by the boundary of AdS. In contrast to quantum field theory in Minkowski spacetime, there is not yet a standard way to resolve the quantization ambiguities arising in its construction. These ambiguities are conveniently encoded in the choice of a complex structure. We explore in this paper the space of complex structures for real scalar Klein-Gordon theory based on a number of criteria. These are: invariance under AdS isometries, induction of a positive definite inner product, compatibility with the standard S-matrix picture and recovery of standard structures in Minkowski spacetime under a limit of vanishing curvature. While there is no complex structure that satisfies all demands, we emphasize two interesting candidates that satisfy most: in one case we have to give up part of the isometry invariance, and in the other case the induced inner product is indefinite.
Gallet, Basile; Nazarenko, Sergey; Dubrulle, Bérengère
2015-07-01
In field theory, particles are waves or excitations that propagate on the fundamental state. In experiments or cosmological models, one typically wants to compute the out-of-equilibrium evolution of a given initial distribution of such waves. Wave turbulence deals with out-of-equilibrium ensembles of weakly nonlinear waves, and is therefore well suited to address this problem. As an example, we consider the complex Klein-Gordon equation with a Mexican-hat potential. This simple equation displays two kinds of excitations around the fundamental state: massive particles and massless Goldstone bosons. The former are waves with a nonzero frequency for vanishing wave number, whereas the latter obey an acoustic dispersion relation. Using wave-turbulence theory, we derive wave kinetic equations that govern the coupled evolution of the spectra of massive and massless waves. We first consider the thermodynamic solutions to these equations and study the wave condensation transition, which is the classical equivalent of Bose-Einstein condensation. We then focus on nonlocal interactions in wave-number space: we study the decay of an ensemble of massive particles into massless ones. Under rather general conditions, these massless particles accumulate at low wave number. We study the dynamics of waves coexisting with such a strong condensate, and we compute rigorously a nonlocal Kolmogorov-Zakharov solution, where particles are transferred nonlocally to the condensate, while energy cascades towards large wave numbers through local interactions. This nonlocal cascading state constitutes the intermediate asymptotics between the initial distribution of waves and the thermodynamic state reached in the long-time limit. PMID:26274249
NASA Astrophysics Data System (ADS)
Jia, Chun-Sheng; Chen, Tao; He, Su
2013-03-01
By employing the improved Greene-Aldrich approximation scheme to deal with the centrifugal term, we solve approximately the Klein-Gordon equation with the improved expression of the Manning-Rosen empirical potential energy model. The bound state energy equation and the unnormalized radial wave functions have been approximately obtained by using the supersymmetric WKB approach and the function analysis method. The relativistic vibrational transition frequencies for the a3Σu+ state of 7Li2 molecule have been computed by using the Manning-Rosen potential model. The relativistic vibrational transition frequencies are in good agreement with the observed data.
NASA Astrophysics Data System (ADS)
Chen, Chang-Yuan; Lu, Fa-Lin; Sun, Dong-Sheng
2008-12-01
In this paper, using the exponential function transformation approach along with an approximation for the centrifugal potential, the radial Klein-Gordon equation with the vector and scalar Hulthén potential is transformed to a hypergeometric differential equation. The approximate analytical solutions of t-waves scattering states are presented. The normalized wave functions expressed in terms of hypergeometric functions of scattering states on the “ k/2π scale” and the calculation formula of phase shifts are given. The physical meaning of the approximate analytical solution is discussed.
NASA Astrophysics Data System (ADS)
Chen, Chang-Yuan; Lu, Fa-Lin; Sun, Dong-Sheng
2008-12-01
In this paper, using the exponential function transformation approach along with an approximation for the centrifugal potential, the radial Klein-Gordon equation with the vector and scalar Hulthén potential is transformed to a hypergeometric differential equation. The approximate analytical solutions of t-waves scattering states are presented. The normalized wave functions expressed in terms of hypergeometric functions of scattering states on the "k/2π scale" and the calculation formula of phase shifts are given. The physical meaning of the approximate analytical solution is discussed.
NASA Astrophysics Data System (ADS)
Bialynicki-Birula, Iwo
2013-03-01
General solutions of the Klein-Gordon equation satisfying the Dirichlet boundary conditions on one fixed wall and the other wall moving with a constant velocity are derived. These solutions are specified by an arbitrary periodic function whose period is equal to twice the value of the rapidity of the moving wall. Choosing this function as a combination of trigonometric functions one obtains the solutions derived recently by Koehn. The method is also tested in the case of the d'Alembert equation where it reproduces in a simple manner well-known results.
NASA Astrophysics Data System (ADS)
Aggoun, L.; Benamira, F.; Guechi, L.; Sadoun, M. A.
2016-04-01
The Green's function associated with a Klein-Gordon particle moving in a D-dimensional space under the action of vector plus scalar q-deformed Hulthén potentials is constructed by path integration for {q ≥ 1} and {1/α ln q < r < infty}. An appropriate approximation of the centrifugal potential term and the technique of space-time transformation are used to reduce the path integral for the generalized Hulthén potentials into a path integral for q-deformed Rosen-Morse potential. Explicit path integration leads to the radial Green's function for any l state in closed form. The energy spectrum and the correctly normalized wave functions, for a state of orbital quantum number {l ≥ 0}, are obtained. Eventually, the vector q-deformed Hulthén potential and the Coulomb potentials in D dimensions are considered as special cases.
NASA Astrophysics Data System (ADS)
Ballesteros, Miguel; Weder, Ricardo
2016-04-01
The study of obstacle scattering for the Klein-Gordon equation in the presence of long-range magnetic potentials is addressed. Previous results of the authors are extended to the long-range case and the results the authors previously proved for high-momenta long-range scattering for the Schrödinger equation are brought to the relativistic scenario. It is shown that there are important differences between relativistic and non-relativistic scattering concerning the long range. In particular, it is proven that the electric potential can be recovered without assuming the knowledge of the long-range part of the magnetic potential, which has to be supposed in the non-relativistic case. The electric potential and the magnetic field are recovered from the high-momenta limit of the scattering operator, as well as fluxes modulo 2π around the handles of the obstacle. Moreover, it is proven that for every \\hat{{v}}\\in {{{S}}}2, {A}∞ (\\hat{{v}})+{A}∞ (-\\hat{{v}}) can be reconstructed, where {A}∞ is the long-range part of the magnetic potential. A simple formula for the high-momenta limit of the scattering operator is given in terms of magnetic fluxes over handles of the obstacle and long-range magnetic fluxes at infinity, that are introduced in this paper. The appearance of these long-range magnetic fluxes is a new effect in scattering theory. Research partially supported by the project PAPIIT-DGAPA UNAM IN102215.
A Klein-Gordon acoustic theory
Anno, P.D.
1992-12-01
Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell's Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.
A Klein-Gordon acoustic theory
Anno, P.D.
1992-12-01
Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell`s Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.
A Symmetrical Interpretation of the Klein-Gordon Equation
NASA Astrophysics Data System (ADS)
Heaney, Michael B.
2013-06-01
This paper presents a new Symmetrical Interpretation (SI) of relativistic quantum mechanics which postulates: quantum mechanics is a theory about complete experiments, not particles; a complete experiment is maximally described by a complex transition amplitude density; and this transition amplitude density never collapses. This SI is compared to the Copenhagen Interpretation (CI) for the analysis of Einstein's bubble experiment. This SI makes several experimentally testable predictions that differ from the CI, solves one part of the measurement problem, resolves some inconsistencies of the CI, and gives intuitive explanations of some previously mysterious quantum effects.
Nonlinear instabilities of multi-site breathers in Klein-Gordon lattices
Cuevas-Maraver, Jesus; Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.
2015-12-14
Here, we explore the possibility of multi-site breather states in a nonlinear Klein–Gordon lattice to become nonlinearly unstable, even if they are found to be spectrally stable. The mechanism for this nonlinear instability is through the resonance with the wave continuum of a multiple of an internal mode eigenfrequency in the linearization of excited breather states. For the nonlinear instability, the internal mode must have its Krein signature opposite to that of the wave continuum. This mechanism is not only theoretically proposed, but also numerically corroborated through two concrete examples of the Klein–Gordon lattice with a soft (Morse) and amore » hard (Φ4) potential. Compared to the case of the nonlinear Schrödinger lattice, the Krein signature of the internal mode relative to that of the wave continuum may change depending on the period of the multi-site breather state. For the periods for which the Krein signatures of the internal mode and the wave continuum coincide, multi-site breather states are observed to be nonlinearly stable.« less
Perturbed Coulomb potentials in the Klein-Gordon equation via the asymptotic iteration method
Barakat, T.
2009-03-15
The asymptotic iteration method is used to construct the exact energy eigenvalues for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector and Lorentz scalar Coulombic potentials. Highly accurate and rapidly converging ground-state energies for Lorentz vector Coulomb with a Lorentz vector or a Lorentz scalar linear potential, V(r)=-{lambda}{sub 1}/r+krandV(r)=-{lambda}{sub 1}/randW(r)=kr, respectively, are obtained.
Nonlinear instabilities of multi-site breathers in Klein-Gordon lattices
Cuevas-Maraver, Jesus; Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.
2015-12-14
Here, we explore the possibility of multi-site breather states in a nonlinear Klein–Gordon lattice to become nonlinearly unstable, even if they are found to be spectrally stable. The mechanism for this nonlinear instability is through the resonance with the wave continuum of a multiple of an internal mode eigenfrequency in the linearization of excited breather states. For the nonlinear instability, the internal mode must have its Krein signature opposite to that of the wave continuum. This mechanism is not only theoretically proposed, but also numerically corroborated through two concrete examples of the Klein–Gordon lattice with a soft (Morse) and a hard (Φ^{4}) potential. Compared to the case of the nonlinear Schrödinger lattice, the Krein signature of the internal mode relative to that of the wave continuum may change depending on the period of the multi-site breather state. For the periods for which the Krein signatures of the internal mode and the wave continuum coincide, multi-site breather states are observed to be nonlinearly stable.
Generalized Klein-Gordon models: behavior around the ground state condensate.
Kuetche, Victor K
2014-07-01
In this work, we investigate the balance between the nonlinear and linear interaction energy of an interparticle anharmonic system in the vicinity of the ground state condensate. As a result, we find that the nonlinear interaction energy is very significant in the vicinity of each degree of freedom. We address some potential applications of the findings to miscellaneous areas of interests such as soliton theory, hydrodynamics, solid state physics, ferromagnetic and ferroelectric domain walls, condensed matter physics, and particle physics, among others. PMID:25122243
NASA Astrophysics Data System (ADS)
Bialynicki-Birula, Iwo
2004-05-01
New solutions in the classical and quantum theory of relativistic charged particles will be presented. They describe a beam of particles guided by an electromagnetic vortex. The beam stabilization is caused by the same mechanism that confines particles in the Paul trap and the Trojan wave packets of electrons in atoms.
Separability of Hamilton-Jacobi and Klein-Gordon equations in general Kerr-NUT-AdS spacetimes
NASA Astrophysics Data System (ADS)
Frolov, Valeri P.; Krtous, Pavel; Kubiznák, David
2007-02-01
We demonstrate the separability of the Hamilton-Jacobi and scalar field equations in general higher dimensional Kerr-NUT-AdS spacetimes. No restriction on the parameters characterizing these metrics is imposed.
NASA Astrophysics Data System (ADS)
Suárez, Abril; Matos, Tonatiuh
2014-02-01
In this paper, the thermal evolution of scalar field dark matter (SFDM) particles at finite cosmological temperatures is studied. Starting with a real SF in a thermal bath and using the one-loop quantum corrections potential, we rewrite Klein-Gordon’s equation in its hydrodynamical representation and study the phase transition of this SF due to a Z2 symmetry breaking of its potential. A very general version of a nonlinear Schrödinger equation is obtained. When introducing Madelung’s representation, the continuity and momentum equations for a non-ideal SFDM fluid are formulated, and the cosmological scenario with the SFDM described in analogy to an imperfect fluid is then considered where dissipative contributions are obtained in a natural way. Additional terms appear in the results compared to those in the classical version commonly used to describe the ΛCDM model, i.e., the ideal fluid. The equations and parameters that characterize the physical properties of the system such as its energy, momentum and viscous flow are related to the temperature of the system, scale factor, Hubble’s expansion parameter and the matter energy density. Finally, some details on how galaxy halos and smaller structures might be able to form by condensation of this SF are given.
Baczewski, Andrew David; Vikram, Melapudi; Shanker, Balasubramaniam; Kempel, Leo
2010-08-27
Diffusion, lossy wave, and Klein–Gordon equations find numerous applications in practical problems across a range of diverse disciplines. The temporal dependence of all three Green’s functions are characterized by an infinite tail. This implies that the cost complexity of the spatio-temporal convolutions, associated with evaluating the potentials, scales as O(Ns2Nt2), where Ns and Nt are the number of spatial and temporal degrees of freedom, respectively. In this paper, we discuss two new methods to rapidly evaluate these spatio-temporal convolutions by exploiting their block-Toeplitz nature within the framework of accelerated Cartesian expansions (ACE). The first scheme identifies a convolution relation inmore » time amongst ACE harmonics and the fast Fourier transform (FFT) is used for efficient evaluation of these convolutions. The second method exploits the rank deficiency of the ACE translation operators with respect to time and develops a recursive numerical compression scheme for the efficient representation and evaluation of temporal convolutions. It is shown that the cost of both methods scales as O(NsNtlog2Nt). Furthermore, several numerical results are presented for the diffusion equation to validate the accuracy and efficacy of the fast algorithms developed here.« less
Baczewski, Andrew David; Vikram, Melapudi; Shanker, Balasubramaniam; Kempel, Leo
2010-08-27
Diffusion, lossy wave, and Klein–Gordon equations find numerous applications in practical problems across a range of diverse disciplines. The temporal dependence of all three Green’s functions are characterized by an infinite tail. This implies that the cost complexity of the spatio-temporal convolutions, associated with evaluating the potentials, scales as O(N_{s}^{2}N_{t}^{2}), where N_{s} and N_{t} are the number of spatial and temporal degrees of freedom, respectively. In this paper, we discuss two new methods to rapidly evaluate these spatio-temporal convolutions by exploiting their block-Toeplitz nature within the framework of accelerated Cartesian expansions (ACE). The first scheme identifies a convolution relation in time amongst ACE harmonics and the fast Fourier transform (FFT) is used for efficient evaluation of these convolutions. The second method exploits the rank deficiency of the ACE translation operators with respect to time and develops a recursive numerical compression scheme for the efficient representation and evaluation of temporal convolutions. It is shown that the cost of both methods scales as O(N_{s}N_{t}log^{2}N_{t}). Furthermore, several numerical results are presented for the diffusion equation to validate the accuracy and efficacy of the fast algorithms developed here.
NASA Astrophysics Data System (ADS)
Wu, Shuang-Qing
2009-03-01
It is shown that the Dirac equation is separable by variables in a five-dimensional rotating Kerr (anti-)de Sitter black hole with two independent angular momenta. A first-order symmetry operator that commutes with the Dirac operator is constructed in terms of a rank-3 Killing Yano tensor whose square is a second-order symmetric Stäckel Killing tensor admitted by the five-dimensional Kerr (anti-)de Sitter spacetime. We highlight the construction procedure of such a symmetry operator. In addition, the first law of black hole thermodynamics has been extended to the case that the cosmological constant can be viewed as a thermodynamical variable.
NASA Astrophysics Data System (ADS)
Sammelson, Robert Erik; Heidari, Alireza; Tayyari, Sayyed Faramarz
2010-05-01
This article has been retracted at the request of the Editor-in-Chief and Author. Please see Elsevier Policy on Article Withdrawal. Reason: The authors have plagiarized part of a paper that had already appeared in Iranian Journal of Physics Research. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and we apologize to readers of the journal that this was not detected during the submission process.
Bialynicki-Birula, Iwo
2004-07-01
It is shown that electromagnetic vortices can act as beam guides for charged particles. The confinement in the transverse directions is due to the rotation of the electric and magnetic fields around the vortex line. A large class of exact solutions describing various types of relativistic beams formed by an electromagnetic wave with a simple vortex line is found both in the classical and in the quantum case. In the second case, the motion in the transverse direction is fully quantized. Particle trajectories trapped by a vortex are very similar to those in a helical undulator. PMID:15323882
Relative unitary implementability of perturbed quantum field dynamics on de-Sitter space
NASA Astrophysics Data System (ADS)
Poon, Gary K.
In this article, we study the quantum dynamics of a Klein-Gordon field on de-Sitter space. We prove time evolution is not unitarily implementable. We also consider a Klein-Gordon field perturbed by a local potential V. In this case we prove that the deviation from the V = 0 dynamics is unitarily implementable.
NASA Astrophysics Data System (ADS)
Woltjer, L.
1987-06-01
En la reunion celebrada en diciembre dei ano pasado informe al Consejo de mi deseo de terminar mi contrato como Director General de la ESO una vez que fuera aprobado el proyecto dei VLT, que se espera sucedera hacia fines de este aAo. Cuando fue renovada mi designacion hace tres aAos, el Consejo conocia mi intencion de no completar los cinco aAos dei contrato debido a mi deseo de disponer de mas tiempo para otras actividades. Ahora, una vez terminada la fase preparatoria para el VLT, Y habiendose presentado el proyecto formalmente al Consejo el dia 31 de marzo, y esperando su muy probable aprobacion antes dei termino de este ano, me parece que el 10 de enero de 1988 presenta una excelente fecha para que se produzca un cambio en la administracion de la ESO.
Noncommutativity and the Friedmann Equations
NASA Astrophysics Data System (ADS)
Sabido, M.; Guzmán, W.; Socorro, J.
2010-07-01
In this paper we study noncommutative scalar field cosmology, we find the noncommutative Friedmann equations as well as the noncommutative Klein-Gordon equation, interestingly the noncommutative contributions are only present up to second order in the noncommutitive parameter.
Hawking Temperature of an Arbitrarily Accelerating Black Hole
NASA Astrophysics Data System (ADS)
Pan, Wei-Zhen; Liu, Wei
2014-09-01
Hawking temperature of an arbitrarily accelerating black hole with electric and magnetic charges are obtained based on the Klein-Gordon equation with a correct-dimension new tortoise coordinate transformation.
Superradiance from a charged dilation black hole
Shiraishi, K. )
1992-12-07
In this paper, the authors study the behavior of the wave function of charged Klein-Gordon field around a charge dilaton black hole. The rate of spontaneous charge loss is estimated for large black hole case.
Dielectric permittivity of quantum plasma. Part I
NASA Astrophysics Data System (ADS)
Bobylev, Yu. V.; Kuzelev, M. V.
2014-05-01
Collisionless quantum plasma models based on the Schröbinger, Klein-Gordon, Dirac, and Pauli equations are considered. The transverse and longitudinal dielectric permittivities of isotropic quantum plasma are calculated in the frameworks of the models based on the Schröbinger and Klein-Gordon equations without allowance for the particle spin. Dispersion relations for transverse-longitudinal waves in beams of spinless quantum particles are derived, and the simplest quantum waves are analyzed.
Quantum Radiation of a Non-stationary Kerr Newman Black Hole in de Sitter Space Time
NASA Astrophysics Data System (ADS)
Jiang, Qing-Quan; Yang, Shu-Zheng
2006-12-01
Hawking radiation of Klein-Gordon and Dirac particles in a non-stationary Kerr-Newman-de-Sitter black hole is studied by introducing a new tortoise coordinate transformation. The result shows that the Fermi-Dirac radiant spectrum displays a new term that represents the interaction between the spin of spinor particles and the rotation of black holes, which is absent in the Bose-Einstein distribution of Klein-Gordon particles.
A Lagrangian for mass dimension one fermionic dark matter
NASA Astrophysics Data System (ADS)
Lee, Cheng-Yang
2016-09-01
The mass dimension one fermionic field associated with Elko satisfies the Klein-Gordon but not the Dirac equation. However, its propagator is not a Green's function of the Klein-Gordon operator. We propose an infinitesimal deformation to the propagator such that it admits an operator in which the deformed propagator is a Green's function. The field is still of mass dimension one, but the resulting Lagrangian is modified in accordance with the operator.
Hawking radiation of scalars from accelerating and rotating black holes with NUT parameter
NASA Astrophysics Data System (ADS)
Jan, Khush; Gohar, H.
2014-03-01
We study the quantum tunneling of scalars from charged accelerating and rotating black hole with NUT parameter. For this purpose we use the charged Klein-Gordon equation. We apply WKB approximation and the Hamilton-Jacobi method to solve charged Klein-Gordon equation. We find the tunneling probability of outgoing charged scalars from the event horizon of this black hole, and hence the Hawking temperature for this black hole
Separating para and ortho water.
Horke, Daniel A; Chang, Yuan-Pin; Długołęcki, Karol; Küpper, Jochen
2014-10-27
Water exists as two nuclear-spin isomers, para and ortho, determined by the overall spin of its two hydrogen nuclei. For isolated water molecules, the conversion between these isomers is forbidden and they act as different molecular species. Yet, these species are not readily separated, and no pure para sample has been produced. Accordingly, little is known about their specific physical and chemical properties, conversion mechanisms, or interactions. The production of isolated samples of both spin isomers is demonstrated in pure beams of para and ortho water in their respective absolute ground state. These single-quantum-state samples are ideal targets for unraveling spin-conversion mechanisms, for precision spectroscopy and fundamental symmetry-breaking studies, and for spin-enhanced applications, for example laboratory astrophysics and astrochemistry or hypersensitized NMR experiments. PMID:25196938
El astronauta de la NASA José Hernández alienta a los estudiantes a que sigan sus sueños. Hernández también habla acerca del papel que juegan los padres para ayudar a que sus hijos hagan realidad s...
NASA Astrophysics Data System (ADS)
Belich, H.; Bakke, K.
2016-03-01
The behavior of a relativistic scalar particle subject to a scalar potential under the effects of the violation of the Lorentz symmetry in the cosmic string space-time is discussed. It is considered two possible scenarios of the Lorentz symmetry breaking in the CPT-even gauge sector of the Standard Model Extension defined by a tensor (KF)μναβ. Then, by introducing a scalar potential as a modification of the mass term of the Klein-Gordon equation, it is shown that the Klein-Gordon equation in the cosmic string space-time is modified by the effects of the Lorentz symmetry violation backgrounds and bound state solution to the Klein-Gordon equation can be obtained.
The two faces of sound in BECs
NASA Astrophysics Data System (ADS)
Barceló, C.; Garay, L. J.; Jannes, G.
2010-12-01
Fluctuations around a Bose-Einstein condensate can be described by means of Bogolubov theory leading to the notion of quasiparticle and antiquasiparticle familiar to non-relativistic condensed matter practitioners. On the other hand, we already know that these perturbations evolve according to a relativistic Klein-Gordon equation in the long wavelength approximation. For shorter wavelengths, we show that this equation acquires nontrivial corrections which modify the Klein-Gordon product. In this approach, quasiparticles can also be defined (up to the standard ambiguities due to observer-dependence). We demonstrate that—in the low as well as in the high energy regimes—both concepts of quasiparticle are actually the same, regardless of the formalism (Bogolubov or Klein-Gordon) used to describe them. These results also apply to any barotropic, inviscid, irrotational fluid, with or without quantum potential.
NASA Astrophysics Data System (ADS)
Ikhdair, Sameer; Sever, Ramazan
2008-03-01
The Klein-Gordon equation in D-dimensions for a recently proposed ring-shaped Kratzer potential is solved analytically by means of the conventional Nikiforov-Uvarov method. The exact energy bound states and the corresponding wave functions of the Klein-Gordon are obtained in the presence of the non-central equal scalar and vector potentials. The results obtained in this work are more general and can be reduced to the standard forms in three dimensions given by other works.
Uniqueness of conserved currents in quantum mechanics
NASA Astrophysics Data System (ADS)
Holland, P.
2003-10-01
It is proved by a functional method that the conventional expression for the Dirac current is the only conserved 4-vector implied by the Dirac equation that is a function of just the quantum state. The demonstration is extended to derive the unique conserved currents implied by the coupled Maxwell-Dirac equations and the Klein-Gordon equation. The uniqueness of the usual Pauli and Schrödinger currents follows by regarding these as the non-relativistic limits of the Dirac and Klein-Gordon currents, respectively. The existence and properties of further conserved vectors that are not functions of just the state is examined.
Massless Spin-Zero Particle and the Classical Action via Hamilton-Jacobi Equation in Gödel Universe
NASA Astrophysics Data System (ADS)
Bahrehbakhsh, A. F.; Momeni, D.; Myrzakulov, R.
2012-08-01
In this letter we investigate the separability of the Klein-Gordon and Hamilton-Jacobi equation in Gödel universe. We show that the Klein-Gordon eigen modes are quantized and the complete spectrum of the particle's energy is a mixture of an azimuthal quantum number, m and a principal quantum number, n and a continuous wave number k. We also show that the Hamilton-Jacobi equation gives a closed function for classical action. These results may be used to calculate the Casimir vacuum energy in Gödel universe.
Functional Expression of Drosophila para Sodium Channels
Warmke, Jeffrey W.; Reenan, Robert A.G.; Wang, Peiyi; Qian, Su; Arena, Joseph P.; Wang, Jixin; Wunderler, Denise; Liu, Ken; Kaczorowski, Gregory J.; Ploeg, Lex H.T. Van der; Ganetzky, Barry; Cohen, Charles J.
1997-01-01
The Drosophila para sodium channel α subunit was expressed in Xenopus oocytes alone and in combination with tipE, a putative Drosophila sodium channel accessory subunit. Coexpression of tipE with para results in elevated levels of sodium currents and accelerated current decay. Para/TipE sodium channels have biophysical and pharmacological properties similar to those of native channels. However, the pharmacology of these channels differs from that of vertebrate sodium channels: (a) toxin II from Anemonia sulcata, which slows inactivation, binds to Para and some mammalian sodium channels with similar affinity (Kd ≅ 10 nM), but this toxin causes a 100-fold greater decrease in the rate of inactivation of Para/TipE than of mammalian channels; (b) Para sodium channels are >10-fold more sensitive to block by tetrodotoxin; and (c) modification by the pyrethroid insecticide permethrin is >100-fold more potent for Para than for rat brain type IIA sodium channels. Our results suggest that the selective toxicity of pyrethroid insecticides is due at least in part to the greater affinity of pyrethroids for insect sodium channels than for mammalian sodium channels. PMID:9236205
Laparoscopic extraperitoneal para-aortic lymphadenectomy
Iserte, Pablo Padilla; Minig, Lucas; Zorrero, Cristina
2015-01-01
Lymph nodes are the main pathway in the spread of gynaecological malignancies, being a well-known prognostic factor. Lymph node dissection is a complex surgical procedure and requires surgical expertise to perform the procedure, thereby minimising complications. In addition, lymphadenectomy has value in the diagnosis, prognosis, and treatment of patients with gynaecologic cancer. Therefore, a video focused on the para-aortic retroperitoneal anatomy and the surgical technique of the extraperitoneal para-aortic lymphadenectomy is presented. PMID:26435746
Process for para-ethyltoluene dehydrogenation
Chu, C.C.
1986-06-03
A process is described of dehydrogenating para-ethyltoluene to selectively form para-methylstyrene comprising contacting to para-ethyltoluene under dehydrogenation reaction conditions with a catalyst composition comprising: (a) from about 30% to 60% by weight of iron oxide, calculated as ferric oxide; (b) from about 13% to 48% by weight of a potassium compound, calculated as potassium oxide; and (c) from about 0% to 5% by weight of a chromium compound, calculated as chromic oxide. The improvement is described comprising dehydrogenating the para-ethyltoluene with a catalyst composition comprising, in addition to the components (a), (b) and (c), a modifying component (d) capable of rendering the para-methylstyrene-containing dehydrogenation reaction effluent especially resistant to the subsequent formation of popcorn polymers when the dehydrogenation of para-ethyltoluene is conducted over the modified catalyst, the modifying component (d) being a bismuth compound present to the extent of from about 1% to 20% by weight of the catalyst composition, calculated as bismuth trioxide.
Nuevos aspectos en el estudio de la particula D en el experimento FOCUS de Fermilab
Quinones Gonzalez, Jose A.; /Puerto Rico U., Mayaguez
2005-01-01
The purpose of this work is to improve the reconstruction techniques of the decays of the particles that contain charm in the quark composition using the information of the Target Silicon Detector of the experiment E831 (FOCUS). That experiment runs during 1997 to 1998 in Fermilab National Laboratory. The objective of the experiment was improving the understanding of the particles that contain charm. Adding the Target Silicon Detector information in the reconstruction process of the primary vertex the position error. This reduction produces an improvement in the mass signal and the knowledge of the charm particles properties. This ad to the possibility's that in other analysis will use the techniques developed in this work.
The ParaScope parallel programming environment
NASA Technical Reports Server (NTRS)
Cooper, Keith D.; Hall, Mary W.; Hood, Robert T.; Kennedy, Ken; Mckinley, Kathryn S.; Mellor-Crummey, John M.; Torczon, Linda; Warren, Scott K.
1993-01-01
The ParaScope parallel programming environment, developed to support scientific programming of shared-memory multiprocessors, includes a collection of tools that use global program analysis to help users develop and debug parallel programs. This paper focuses on ParaScope's compilation system, its parallel program editor, and its parallel debugging system. The compilation system extends the traditional single-procedure compiler by providing a mechanism for managing the compilation of complete programs. Thus, ParaScope can support both traditional single-procedure optimization and optimization across procedure boundaries. The ParaScope editor brings both compiler analysis and user expertise to bear on program parallelization. It assists the knowledgeable user by displaying and managing analysis and by providing a variety of interactive program transformations that are effective in exposing parallelism. The debugging system detects and reports timing-dependent errors, called data races, in execution of parallel programs. The system combines static analysis, program instrumentation, and run-time reporting to provide a mechanical system for isolating errors in parallel program executions. Finally, we describe a new project to extend ParaScope to support programming in FORTRAN D, a machine-independent parallel programming language intended for use with both distributed-memory and shared-memory parallel computers.
Oxidative para-triflation of acetanilides.
Pialat, Amélie; Liégault, Benoît; Taillefer, Marc
2013-04-01
Direct triflation of acetanilide derivatives with silver triflate has been accomplished under mild iodine(III)-mediated oxidative conditions. The reaction shows excellent regioselectivity for the para position and tolerates a range of ortho and meta substituents on the aromatic ring. This method is also compatible with the preparation of arylnonaflates in synthetically useful yields. PMID:23534500
FDA aprueba la primera inmunoterapia para linfoma
La FDA ha aprobado nivolumab (Opdivo®) para el tratamiento de pacientes con el linfoma clásico de Hodgkin que ha recaído o empeorado después de recibir un trasplante autólogo hematopoyético seguido de brentuximab vedotin (Adcetris®)
Notes on oscillator-like interactions of various spin relativistic particles
NASA Technical Reports Server (NTRS)
Dvoeglazov, Valeri V.; Delsolmesa, Antonio
1995-01-01
The equations for various spin particles with oscillator-like interactions are discussed in this talk. Topics discussed include: (1) comment on 'The Klein-Gordon Oscillator'; (2) the Dirac oscillator in quaternion form; (3) the Dirac-Dowker oscillator; (4) the Weinberg oscillator; and (5) note on the two-body Dirac oscillator.
Hawking Temperature of Acoustic Black Hole
NASA Astrophysics Data System (ADS)
Xie, Zhi Kun
2014-09-01
Using a new tortoise coordinate transformation, the Hawking radiation of the acoustic black hole was discussed by studying the Klein-Gordon equation of scalar particles in the curve space-time. It was found that the Hawking temperature is connected with time and position on the event horizon.
A new method dealing with hawking effects of evaporating black holes
Zhao, Z.; Dai, X. )
1992-06-28
This paper reports that, both the location and the temperature of event horizons of evaporating black holes can be easily given if one proposes the Klein-Gordon equation approaches the standard form of wave equation near event horizons by using tortoise-type coordinates.
Relativistic wave mechanics of spinless particles in a curved space-time.
NASA Astrophysics Data System (ADS)
Cognola, G.; Vanzo, L.; Zerbini, S.
1986-09-01
Starting from the Klein-Gordon equation, the single-particle approximation for a reiativistic scalar particle in the presence of external electromagnetic and gravitational fields is performed. The nonrelativistic limit is obtained by a Foldy-Wouthuysen transformation on a Schrödinger-type equation. The results are then compared with those obtained in classical mechanics.
Positive particle frequencies in some time-periodic universes
NASA Astrophysics Data System (ADS)
Droz-Vincent, Philippe
1996-03-01
We consider the Klein-Gordon equation in FRW-like universes which are periodic in a suitable scale of time. In a remarkable sector of solutions, the Floquet theory of differential equations allows for generalizing the notion of particle frequency. In this sense, the sesquilinear form associated with Gordon's current is positive definite when restricted to the sub-sector of positive frequencies.
Lower bounds for sums of eigenvalues of elliptic operators and systems
Ilyin, Aleksei A
2013-04-30
Two-term lower bounds of Berzin-Li-Yau type are obtained for the sums of eigenvalues of elliptic operators and systems with constant coefficients and Dirichlet boundary conditions. The polyharmonic operator, the Stokes system and its generalizations, the two-dimensional buckling problem, and also the Klein-Gordon operator are considered. Bibliography: 32 titles.
Scalar field conformally coupled to a charged BTZ black hole
NASA Astrophysics Data System (ADS)
Valtancoli, P.
2016-06-01
We study the Klein-Gordon equation of a scalar field conformally coupled to a charged BTZ black hole. The background metric is obtained by coupling a non-linear and conformal invariant Maxwell field to (2 + 1) gravity. We show that the radial part is generally solved by a Heun function and, in the pure gravity limit, by a hypergeometric function.
Non-commutative relativistic equation with a Coulomb potential
Zaim, Slimane; Khodja, Lamine; Delenda, Yazid
2012-06-27
We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the secondorder corrections in the non-commutativity parameter. Phenomenologically we show that noncommutativity plays the role of spin.
Emission of scalar particles from cylindrical black holes
NASA Astrophysics Data System (ADS)
Gohar, H.; Saifullah, K.
2013-01-01
We study quantum tunneling of scalar particles from black strings. For this purpose we apply WKB approximation and Hamilton-Jacobi method to solve the Klein-Gordon equation for outgoing trajectories. We find the tunneling probability of outgoing charged and uncharged scalars from the event horizon of black strings, and hence the Hawking temperature for these black configurations.
Scalar field radiation from dilatonic black holes
NASA Astrophysics Data System (ADS)
Gohar, H.; Saifullah, K.
2012-12-01
We study radiation of scalar particles from charged dilaton black holes. The Hamilton-Jacobi method has been used to work out the tunneling probability of outgoing particles from the event horizon of dilaton black holes. For this purpose we use WKB approximation to solve the charged Klein-Gordon equation. The procedure gives Hawking temperature for these black holes as well.
Plasma analog of particle-pair production
Tsidulko, Yu.A.; Berk, H.L.
1996-09-01
It is shown that the plasma axial shear flow instability satisfies the Klein-Gordon equation. The plasma instability is then shown to be analogous to spontaneous particle-pair production when a potential energy is present that is greater than twice the particle rest mass energy. Stability criteria can be inferred based on field theoretical conservation laws.
Notes on oscillator-like interactions of various spin relativistic particles
Dvoeglazov, V.V.; Delsolmesa, A.
1995-01-01
The equations for various spin particles with oscillator-like interactions are discussed in this talk. Topics discussed include: (1) comment on `The Klein-Gordon Oscillator`; (2) the Dirac oscillator in quaternion form; (3) the Dirac-Dowker oscillator; (4) the Weinberg oscillator; and (5) note on the two-body Dirac oscillator.
Method of Improving the Teaching of Particle Physics in a Noncalculus Course of Physics
NASA Astrophysics Data System (ADS)
Chen, Robert L. W.
The Klein Gordon equation-which describes mesons-can be reformulated to suit students who have no calculus background. The method is arrived at from a review and a reinterpretation of the mechanics of small oscillations. It may serve as a model for the design of new instructions for other areas of particle physics.
Centro para la Salud Mundial (CGH) del NCI
El Centro para la Salud Mundial (CGH) del NCI coordina actividades de investigación y trabaja con socios nacionales e internacionales para comprender y enfrentar la carga que representa el cáncer a nivel mundial.
Para-hydrogen perspectives in hyperpolarized NMR.
Glöggler, Stefan; Colell, Johannes; Appelt, Stephan
2013-10-01
The first instance of para-hydrogen induced polarization (PHIP) in an NMR experiment was serendipitously observed in the 1980s while investigating a hydrogenation reaction (Seldler et al., 1983; Bowers and Weitekamp, 1986, 1987; Eisenschmid et al., 1987) [1-4]. Remarkably a theoretical investigation of the applicability of para-hydrogen as a hyperpolarization agent was being performed in the 1980's thereby quickly providing a theoretical basis for the PHIP-effect (Bowers and Weitekamp, 1986) [2]. The discovery of signal amplification by a non-hydrogenating interaction with para-hydrogen has recently extended the interest to exploit the PHIP effect, as it enables investigation of compounds without structural alteration while retaining the advantages of spectroscopy with hyperpolarized compounds [5]. In this article we will place more emphasis of the future applications of the method while only briefly discussing the efforts that have been made in the understanding of the phenomenon and the development of the method so far. PMID:23932399
Allergic contact dermatitis to para-phenylenediamine.
Jenkins, David; Chow, Elizabeth T
2015-02-01
Exposure to hair dye is the most frequent route of sensitisation to para-phenylenediamine (PPD), a common contact allergen. International studies have examined the profile of PPD, but Australian-sourced information is lacking. Patients are often dissatisfied with advice to stop dyeing their hair. This study examines patients' characteristics, patch test results and outcomes of PPD allergy from a single Australian centre, through a retrospective analysis of patch test data from 2006 to 2013 at the Liverpool Hospital Dermatology Department. It reviews the science of hair dye allergy, examines alternative hair dyes and investigates strategies for hair dyeing. Of 584 patients, 11 were allergic to PPD. Our PPD allergy prevalence rate of 2% is at the lower end of international reported rates. About half these patients also react to para-toluenediamine (PTD). Affected patients experience a significant lifestyle disturbance. In all, 78% tried alternative hair dyes after the patch test diagnosis and more than half continued to dye their hair. Alternative non-PPD hair dyes are available but the marketplace can be confusing. Although some patients are able to tolerate alternative hair dyes, caution is needed as the risk of developing an allergy to other hair dye ingredients, especially PTD, is high. PMID:25302475
On Lightlike Geometry of Para-Sasakian Manifolds
Acet, Bilal Eftal; Kılıç, Erol
2014-01-01
We study lightlike hypersurfaces of para-Sasakian manifolds tangent to the characteristic vector field. In particular, we define invariant lightlike hypersurfaces and screen semi-invariant lightlike hypersurfaces, respectively, and give examples. Integrability conditions for the distributions on a screen semi-invariant lightlike hypersurface of para-Sasakian manifolds are investigated. We obtain a para-Sasakian structure on the leaves of an integrable distribution of a screen semi-invariant lightlike hypersurface. PMID:24892072
Dipolar induced para-hydrogen-induced polarization.
Buntkowsky, Gerd; Gutmann, Torsten; Petrova, Marina V; Ivanov, Konstantin L; Bommerich, Ute; Plaumann, Markus; Bernarding, Johannes
2014-01-01
Analytical expressions for the signal enhancement in solid-state PHIP NMR spectroscopy mediated by homonuclear dipolar interactions and single pulse or spin-echo excitation are developed and simulated numerically. It is shown that an efficient enhancement of the proton NMR signal in solid-state NMR studies of chemisorbed hydrogen on surfaces is possible. Employing typical reaction efficacy, enhancement-factors of ca. 30-40 can be expected both under ALTADENA and under PASADENA conditions. This result has important consequences for the practical application of the method, since it potentially allows the design of an in-situ flow setup, where the para-hydrogen is adsorbed and desorbed from catalyst surfaces inside the NMR magnet. PMID:25218522
Cooling by Para-to-Ortho-Hydrogen Conversion
NASA Technical Reports Server (NTRS)
Sherman, A.; Nast, T.
1983-01-01
Catalyst speeds conversion, increasing capacity of solid hydrogen cooling system. In radial-flow catalytic converter, para-hydrogen is converted to equilibrium mixture of para-hydrogen and ortho-hydrogen as it passes through porous cylinder of catalyst. Addition of catalyst increases capacity of hydrogen sublimation cooling systems for radiation detectors.
Requisitos para utilizar el enlace | Smokefree Español
Espanol.smokefree.gov ofrece apoyo y recursos para norteamericanos que hablan español y quieren dejar de fumar. Este sitio en la red fue creada por la División de Investigación para el Control del Tabaco del Instituto Nacional del Cáncer.
Construction of a Para-Ortho Hydrogen Test Cryostat
NASA Astrophysics Data System (ADS)
Essler, J.; Haberstroh, Ch.
2010-04-01
In a prospective hydrogen economy it is necessary to verify the para concentration of the employed hydrogen. In case of a short storage time of about a few days only it has been shown that a partial conversion into para-hydrogen gives an optimized overall efficiency. Hence, an easy and reliable method of measuring the para-hydrogen concentration is needed. In this paper, the concept and construction of a small test cryostat are described and first results are presented. The measuring principle is based on a catalytic induced adiabatic ortho-para conversion of a hydrogen gas flow starting from a known temperature. The operation of the system only requires a certain amount of liquid nitrogen as coolant. To determine the concentration of para-hydrogen it is only necessary to measure the temperature of the gas before and after the adiabatic catalyst cell. The measuring cryostat is used for further investigation of the spontaneous para-ortho conversion in the supercritical state. In addition, the design of the cryostat allows the investigation of different catalyst materials regarding the catalytic activity and possible degradation by using a known para concentration for the measurement.
a New Equation of State for Solid para-HYDROGEN
NASA Astrophysics Data System (ADS)
Wang, Lecheng; Le Roy, Robert J.; Roy, Pierre-Nicholas
2015-06-01
Solid para-H_2 is a popular accommodating host for impurity spectroscopy due to its unique softness and the spherical symmetry of para-H_2 in its J}=0 rotational level. To simulate the properties of impurity-doped solid para-H_2, a reliable model for the `soft' pure solid para-H_2 at different pressures is highly desirable. While a couple of experimental and theoretical studies aimed at elucidating the equation of state (EOS) of solid para-H_2 have been reported, the calculated EOS was shown to be heavily dependent on the potential energy surface (PES) between two para-H_2 that was used in the simulations. The current study also demonstrates that different choices of the parameters governing the Quantum Monte Carlo simulation could produce different EOS curves. To obtain a reliable model for pure solid para-H_2, we used a new 1-D para-H_2 PES reported by Faruk et al. that was obtained by averaging over Hinde's highly accurate 6-D H_2--H_2 PES. The EOS of pure solid para-H_2 was calculated using the PIMC algorithm with periodic boundary conditions (PBC). To precisely determine the equilibrium density of solid para-H_2, both the value of the PIMC time step (τ) and the number of particles in the PBC cell were extrapolated to convergence. The resulting EOS agreed well with experimental observations, and the hcp structured solid para-H_2 was found to be more stable than the fcc one at 4.2K, in agreement with experiment. The vibrational frequency shift of para-H_2 as a function of the density of the pure solid was also calculated, and the value of the shift at the equilibrium density is found to agree well with experiment. T. Momose, H. Honshina, M. Fushitani and H. Katsuki, Vib. Spectrosc. 34, 95(2004). M. E. Fajardo, J. Phys. Chem. A 117, 13504 (2013). I. F. Silvera, Rev. Mod. Phys. 52, 393(1980). F. Operetto and F. Pederiva, Phys. Rev. B 73, 184124(2006). T. Omiyinka and M. Boninsegni, Phys. Rev. B 88, 024112(2013). N. Faruk, M. Schmidt, H. Li, R. J. Le Roy, and P
ParaDiS-FEM dislocation dynamics simulation code primer
Tang, M; Hommes, G; Aubry, S; Arsenlis, A
2011-09-27
The ParaDiS code is developed to study bulk systems with periodic boundary conditions. When we try to perform discrete dislocation dynamics simulations for finite systems such as thin films or cylinders, the ParaDiS code must be extended. First, dislocations need to be contained inside the finite simulation box; Second, dislocations inside the finite box experience image stresses due to the free surfaces. We have developed in-house FEM subroutines to couple with the ParaDiS code to deal with free surface related issues in the dislocation dynamics simulations. This primer explains how the coupled code was developed, the main changes from the ParaDiS code, and the functions of the new FEM subroutines.
Cooling by conversion of para to ortho-hydrogen
NASA Technical Reports Server (NTRS)
Sherman, A. (Inventor)
1983-01-01
The cooling capacity of a solid hydrogen cooling system is significantly increased by exposing vapor created during evaporation of a solid hydrogen mass to a catalyst and thereby accelerating the endothermic para-to-ortho transition of the vapor to equilibrium hydrogen. Catalyst such as nickel, copper, iron or metal hydride gels of films in a low pressure drop catalytic reactor are suitable for accelerating the endothermic para-to-ortho conversion.
Para hydrogen equilibration in the atmospheres of the outer planets
NASA Technical Reports Server (NTRS)
Conrath, Barney J.
1986-01-01
The thermodynamic behavior of the atmospheres of the Jovian planets is strongly dependent on the extent to which local thermal equilibration of the ortho and para states of molecular hydrogen is achieved. Voyager IRIS data from Jupiter imply substantial departures of the para hydrogen fraction from equilibrium in the upper troposphere at low latitudes, but with values approaching equilibrium at higher latitudes. Data from Saturn are less sensitive to the orth-para ratio, but suggest para hydrogen fractions near the equilibrium value. Above approximately the 200 K temperature level, para hydrogen conversion can enhance the efficiency of convection, resulting in a substantial increase in overturning times on all of the outer planets. Currently available data cannot definitively establish the ortho-para ratios in the atmospheres of Uranus and Neptune, but suggest values closer to local equilibrium than to the 3.1 normal ratio. Modeling of sub-millimeter wavelength measurements of these planets suggest thermal structures with frozen equilibrium lapse rates in their convective regions.
A Comparative Usage-Based Approach to the Reduction of the Spanish and Portuguese Preposition "Para"
ERIC Educational Resources Information Center
Gradoville, Michael Stephen
2013-01-01
This study examines the frequency effect of two-word collocations involving "para" "to," "for" (e.g. "fui para," "para que") on the reduction of "para" to "pa" (in Spanish) and "pra" (in Portuguese). Collocation frequency effects demonstrate that language speakers…
ParaText : scalable text modeling and analysis.
Dunlavy, Daniel M.; Stanton, Eric T.; Shead, Timothy M.
2010-06-01
Automated processing, modeling, and analysis of unstructured text (news documents, web content, journal articles, etc.) is a key task in many data analysis and decision making applications. As data sizes grow, scalability is essential for deep analysis. In many cases, documents are modeled as term or feature vectors and latent semantic analysis (LSA) is used to model latent, or hidden, relationships between documents and terms appearing in those documents. LSA supplies conceptual organization and analysis of document collections by modeling high-dimension feature vectors in many fewer dimensions. While past work on the scalability of LSA modeling has focused on the SVD, the goal of our work is to investigate the use of distributed memory architectures for the entire text analysis process, from data ingestion to semantic modeling and analysis. ParaText is a set of software components for distributed processing, modeling, and analysis of unstructured text. The ParaText source code is available under a BSD license, as an integral part of the Titan toolkit. ParaText components are chained-together into data-parallel pipelines that are replicated across processes on distributed-memory architectures. Individual components can be replaced or rewired to explore different computational strategies and implement new functionality. ParaText functionality can be embedded in applications on any platform using the native C++ API, Python, or Java. The ParaText MPI Process provides a 'generic' text analysis pipeline in a command-line executable that can be used for many serial and parallel analysis tasks. ParaText can also be deployed as a web service accessible via a RESTful (HTTP) API. In the web service configuration, any client can access the functionality provided by ParaText using commodity protocols ... from standard web browsers to custom clients written in any language.
Bosonic pair creation and the Schiff-Snyder-Weinberg effect
NASA Astrophysics Data System (ADS)
Lv, Q. Z.; Bauke, Heiko; Su, Q.; Keitel, C. H.; Grobe, R.
2016-01-01
Interactions between different bound states in bosonic systems can lead to pair creation. We study this process in detail by solving the Klein-Gordon equation on space-time grids in the framework of time-dependent quantum field theory. By choosing specific external field configurations, two bound states can become pseudodegenerate, which is commonly referred to as the Schiff-Snyder-Weinberg effect. These pseudodegenerate bound states, which have complex energy eigenvalues, are related to the pseudo-Hermiticity of the Klein-Gordon Hamiltonian. In this work, the influence of the Schiff-Snyder-Weinberg effect on pair production is studied. A generalized Schiff-Snyder-Weinberg effect, where several pairs of pseudodegenerate states appear, is found in combined electric and magnetic fields. The generalized Schiff-Snyder-Weinberg effect likewise triggers pair creation. The particle number in these situations obeys an exponential growth law in time enhancing the creation of bosons, which cannot be found in fermionic systems.
Photon mirror acceleration in the quantum regime
Mendonça, J. T.; Fedele, R.
2014-12-15
Reflection of an electron beam by an intense laser pulse is considered. This is the so-called photon mirror configuration for laser acceleration in vacuum, where the energy of the incident electron beam is nearly double-Doppler shifted due to reflection on the laser pulse front. A wave-electron optical description for electron reflection and resonant backscattering, due to both linear electric field force and quadratic ponderomotive force, is provided beyond the paraxial approximation. This is done by assuming that the single electron of the beam is spin-less and therefore its motion can be described by a quantum scalar field whose spatiotemporal evolution is governed by the Klein-Gordon equation (Klein-Gordon field). Our present model, not only confirms the classical results but also shows the occurrence of purely quantum effects, such as partial reflection of the incident electron beam and enhanced backscattering due to Bragg resonance.
Bose-Einstein condensates and scalar fields; exploring the similitudes
NASA Astrophysics Data System (ADS)
Castellanos, E.; Macías, A.; Núñez, D.
2014-01-01
We analyze the the remarkable analogy between the classical Klein-Gordon equation for a test scalar field in a flat and also in a curved background, and the Gross-Pitaevskii equation for a Bose-Einstein condensate trapped by an external potential. We stress here that the solution associated with the Klein-Gordon equation (KG) in a flat space time has the same mathematical structure, under certain circumstances, to those obtained for the Gross-Pitaevskii equation, that is, a static soliton solution. Additionally, Thomas-Fermi approximation is applied to the 3-dimensional version of this equation, in order to calculate some thermodynamical properties of the system in curved a space-time back ground. Finally, we stress the fact that a gravitational background provides, in some cases, a kind of confining potential for the scalar field, allowing us to remarks even more the possible connection between scalar fields and the phenomenon of Bose-Einstein condensation.
Second order perturbations during inflation beyond slow-roll
Huston, Ian; Malik, Karim A. E-mail: k.malik@qmul.ac.uk
2011-10-01
We numerically calculate the evolution of second order cosmological perturbations for an inflationary scalar field without resorting to the slow-roll approximation or assuming large scales. In contrast to previous approaches we therefore use the full non-slow-roll source term for the second order Klein-Gordon equation which is valid on all scales. The numerical results are consistent with the ones obtained previously where slow-roll is a good approximation. We investigate the effect of localised features in the scalar field potential which break slow-roll for some portion of the evolution. The numerical package solving the second order Klein-Gordon equation has been released under an open source license and is available for download.
Nonrelativistic quantum dynamics on a cone with and without a constraining potential
Filgueiras, C.; Silva, E. O.; Andrade, F. M.
2012-12-15
In this paper we investigate the bound state problem of nonrelativistic quantum particles on a conical surface. This kind of surface appears as a topological defect in ordinary semiconductors as well as in graphene sheets. Specifically, we compare and discuss the results stemming from two different approaches. In the first one, it is assumed that the charge carriers are bound to the surface by a constraining potential, while the second one is based on the Klein-Gordon type equation on surfaces, without the constraining potential. The main difference between both theories is the presence/absence of a potential which contains the mean curvature of a given surface. This fact changes the dependence of the bound states on the angular momentum l. Moreover, there are bound states that are absent in the Klein-Gordon theory, which instead appear in the Schroedinger one.
Strong-field Breit-Wheeler pair production in short laser pulses: Relevance of spin effects
NASA Astrophysics Data System (ADS)
Jansen, M. J. A.; Kamiński, J. Z.; Krajewska, K.; Müller, C.
2016-07-01
Production of electron-positron pairs in the collision of a high-energy photon with a high-intensity few-cycle laser pulse is studied. By utilizing the frameworks of laser-dressed spinor and scalar quantum electrodynamics, a comparison between the production of pairs of Dirac and Klein-Gordon particles is drawn. Positron energy spectra and angular distributions are presented for various laser parameters. We identify conditions under which predictions from Klein-Gordon theory either closely resemble or largely differ from those of the proper Dirac theory. In particular, we address the question to which extent the relevance of spin effects is influenced by the short duration of the laser pulse.
Scalar waves in the Witten bubble spacetime
Bhawal, B. Raman Research Institute, Bangalore ); Vishveshwara, C.V. )
1990-09-15
Massless scalar waves in the Witten bubble spacetime are studied. The timelike and angular parts of the separated Klein-Gordon equation are written in terms of hyperbolic harmonics characterized by the generalized frequency {omega}. The radial equation is cast into the Schroedinger form. The above mathematical formulation is applied to study the scattering problem, the bound states, and the corresponding stability criteria. The results confirm the concept of a bubble wall as a perfectly reflecting expanding sphere.
Duality of coordinates and matter fields in curved spacetime
NASA Astrophysics Data System (ADS)
De Andrade, M. A.; Vancea, I. V.
2000-02-01
We show that there exists a duality between the local coordinates and the solutions of the Klein-Gordon equation in curved spacetime in the same sense as in the Minkowski spacetime. However, the duality in curved spacetime does not have the same generality as in flat spacetime and it holds only if the system satisfies certain constraints. We derive these constraints and the basic equations of duality and discuss the implications in the quantum theory.
Gravity and duality between coordinates and matter fields
NASA Astrophysics Data System (ADS)
Vancea, I. V.
2000-05-01
We use the duality between the local Cartezian coordinates and the solutions of the Klein-Gordon equation to parametrize locally the spacetime in terms of wave functions and prepotentials. The components of metric, metric connection, curvature as well as the Einstein equation are given in this parametrization. We also discuss the local duality between coordinates and quantum fields and the metric in this later reparametrization.
NASA Astrophysics Data System (ADS)
Bauke, Heiko; Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.; Ahrens, Sven; Müller, Carsten; Keitel, Christoph H.
2013-05-01
Computational methods are indispensable to study the quantum dynamics of relativistic light-matter interactions in parameter regimes where analytical methods become inapplicable. We present numerical methods for solving the time-dependent Dirac equation and the time-dependent Klein-Gordon equation and their implementation on high performance graphics cards. These methods allow us to study tunneling from hydrogen-like highly charged ions in strong laser fields and Kapitza-Dirac scattering in the relativistic regime.
Hertz Vectors and the Electromagnetic-Quantum Equations
NASA Astrophysics Data System (ADS)
Kouzaev, Guennadi A.
In this letter, a new form of electromagnetic-quantum equations is proposed. The electric and magnetic potentials are expressed through a single Hertz vector, and the systems of quantum and Maxwell equations are transformed into more compact integro-differential ones. These new forms are given for the Schrödinger, Pauli, Dirac and Klein-Gordon equations, and a practical way to calculate them by available software tools is considered.
Rindler effect for a nonuniformly accelerating observer
Zhu Jian-yang; Bao Aidong; Zhao Zheng
1995-10-01
Both the Klein-Gordon equation and the Dirac equation are dealt with in the generalized Rindler space-time of a nonuniformly accelerating observer. Making use of a new method and introducing a tortoise-type coordinate transformation, it is proved that there exist an event horizon and thermal radiation depending on time in the space-time. The Hawking-Unruh temperature is proportional to the variable acceleration.
Negative energy waves and quantum relativistic Buneman instabilities.
Haas, F; Eliasson, B; Shukla, P K
2012-09-01
The quantum relativistic Buneman instability is investigated theoretically using a collective Klein-Gordon model for the electrons and a cold fluid model for the ions. The growth rate and unstable wave spectrum is investigated in different parameter regimes corresponding to various degrees of relativistic and quantum effects. The results may be important for streaming instabilities involving ion dynamics in very dense plasmas. PMID:23031033
Blowup results for the KGS system with higher order Yukawa coupling
Shi, Qi-Hong; Li, Wan-Tong; Wang, Shu
2015-10-15
In this paper, we investigate the Klein-Gordon-Schrödinger (KGS) system with higher order Yukawa coupling in spatial dimensions N ≥ 3. We establish a perturbed virial type identity and prove blowup results relied on Lyapunov functionals for KGS system with a negative energy level. Additionally, we give a result with respect to the blowup rate in finite time for the radial solution in 3 spatial dimensions.
Acoustic black holes: massless scalar field analytic solutions and analogue Hawking radiation
NASA Astrophysics Data System (ADS)
Vieira, H. S.; Bezerra, V. B.
2016-07-01
We obtain the analytic solutions of the radial part of the massless Klein-Gordon equation in the spacetime of both three dimensional rotating and four dimensional canonical acoustic black holes, which are given in terms of the confluent Heun functions. From these solutions, we obtain the scalar waves near the acoustic horizon. We discuss the analogue Hawking radiation of massless scalar particles and the features of the spectrum associated with the radiation emitted by these acoustic black holes.
On the correspondence between quantum and classical variational principles
Ruiz, D. E.; Dodin, I. Y.
2015-06-10
Here, classical variational principles can be deduced from quantum variational principles via formal reparameterization of the latter. It is shown that such reparameterization is possible without invoking any assumptions other than classicality and without appealing to dynamical equations. As examples, first principle variational formulations of classical point-particle and cold-fluid motion are derived from their quantum counterparts for Schrodinger, Pauli, and Klein-Gordon particles.
Quantum tunneling from scalar fields in rotating black strings
NASA Astrophysics Data System (ADS)
Gohar, H.; Saifullah, K.
2013-08-01
Using the Hamilton-Jacobi method of quantum tunneling and complex path integration, we study Hawking radiation of scalar particles from rotating black strings. We discuss tunneling of both charged and uncharged scalar particles from the event horizons. For this purpose, we use the Klein-Gordon equation and find the tunneling probability of outgoing scalar particles. The procedure gives Hawking temperature for rotating charged black strings as well.
Resolution of curvature singularities from quantum mechanical and loop perspective
NASA Astrophysics Data System (ADS)
Tahamtan, T.; Svítek, O.
2014-08-01
We analyze the persistence of curvature singularities when analyzed using quantum theory. First, quantum test particles obeying the Klein-Gordon and Chandrasekhar-Dirac equation are used to probe the classical timelike naked singularity. We show that the classical singularity is felt even by our quantum probes. Next, we use loop quantization to resolve a singularity hidden beneath the horizon. The singularity is resolved in this case.
The Green function for the Duffin-Kemmer-Petiau equation
NASA Astrophysics Data System (ADS)
Boutabia-Chéraitia, B.; Boudjedaa, T.
2012-10-01
We present a calculation of the Green function for the Duffin-Kemmer-Petiau equation in the case of scalar and vectorial particles interacting with a square barrier potential, and relate it to that of the Klein-Gordon equation. A formal Hamiltonian of the Duffin-Kemmer-Petiau theory is first developed using the Feshbach-Villars analogy and the Sakata and Taketani decomposition. The coefficients of reflection and transmission are deduced.
On the correspondence between quantum and classical variational principles
Ruiz, D. E.; Dodin, I. Y.
2015-10-01
Classical variational principles can be deduced from quantum variational principles via formal reparameterization of the latter. It is shown that such reparameterization is possible without invoking any assumptions other than classicality and without appealing to dynamical equations. As examples, first principle variational formulations of classical point-particle and cold-fluid motion are derived from their quantum counterparts for Schrodinger, Pauli, and Klein-Gordon particles. (C) 2015 Elsevier B.V. All rights reserved.
On the correspondence between quantum and classical variational principles
NASA Astrophysics Data System (ADS)
Ruiz, D. E.; Dodin, I. Y.
2015-10-01
Classical variational principles can be deduced from quantum variational principles via formal reparameterization of the latter. It is shown that such reparameterization is possible without invoking any assumptions other than classicality and without appealing to dynamical equations. As examples, first principle variational formulations of classical point-particle and cold-fluid motion are derived from their quantum counterparts for Schrödinger, Pauli, and Klein-Gordon particles.
Una técnica para filtrar patrones de fringing
NASA Astrophysics Data System (ADS)
Ostrov, P. G.
Se presenta una nueva técnica para filtrar los patrones de fringing producidos en los CCDs tipo RCA. El método consiste en construir un mapa con los ángulos de inclinación de las franjas en cada punto de la imagen. Este mapa es ulteriormente utilizado para alinear con el patrón de interferencia una ventana estrecha, sobre la que se aplica un filtro de mediana. Este procedimiento permite eliminar la mayor parte del ruido del patrón de fringing sin destruirlo.
Quantum singularities in (2+1) dimensional matter coupled black hole spacetimes
Unver, O.; Gurtug, O.
2010-10-15
Quantum singularities considered in the 3D Banados-Teitelboim-Zanelli (BTZ) spacetime by Pitelli and Letelier [Phys. Rev. D 77, 124030 (2008)] is extended to charged BTZ and 3D Einstein-Maxwell-dilaton gravity spacetimes. The occurrence of naked singularities in the Einstein-Maxwell extension of the BTZ spacetime both in linear and nonlinear electrodynamics as well as in the Einstein-Maxwell-dilaton gravity spacetimes are analyzed with the quantum test fields obeying the Klein-Gordon and Dirac equations. We show that with the inclusion of the matter fields, the conical geometry near r=0 is removed and restricted classes of solutions are admitted for the Klein-Gordon and Dirac equations. Hence, the classical central singularity at r=0 turns out to be quantum mechanically singular for quantum particles obeying the Klein-Gordon equation but nonsingular for fermions obeying the Dirac equation. Explicit calculations reveal that the occurrence of the timelike naked singularities in the considered spacetimes does not violate the cosmic censorship hypothesis as far as the Dirac fields are concerned. The role of horizons that clothes the singularity in the black hole cases is replaced by repulsive potential barrier against the propagation of Dirac fields.
NASA Astrophysics Data System (ADS)
Barceló, C.; Garay, L. J.; Jannes, G.
2010-08-01
Fluctuations around a Bose-Einstein condensate can be described by means of Bogolubov theory leading to the notion of quasiparticle and antiquasiparticle familiar to nonrelativistic condensed-matter practitioners. On the other hand, we already know that these perturbations evolve according to a relativistic Klein-Gordon equation in the long-wavelength approximation. For shorter wavelengths, we show that this equation acquires nontrivial corrections which modify the Klein-Gordon product. In this approach, quasiparticles can also be defined (up to the standard ambiguities due to observer dependence). We demonstrate that—in the low-energy as well as in the high-energy regimes—both concepts of quasiparticle are actually the same, regardless of the formalism (Bogolubov or Klein-Gordon) used to describe them. These results also apply to any barotropic, inviscid, irrotational fluid, with or without quantum potential. Finally, we illustrate how the quantization of these systems of quasiparticles proceeds by analyzing a stationary configuration containing an acoustic horizon. We show that there are several possible choices of a regular vacuum state, including a regular generalization of the Boulware vacuum. Issues such us Hawking radiation crucially depend on this vacuum choice.
Analyzing and Visualizing Cosmological Simulations with ParaView
Woodring, Jonathan; Heitmann, Katrin; Ahrens, James P; Fasel, Patricia; Hsu, Chung-Hsing; Habib, Salman; Pope, Adrian
2011-01-01
The advent of large cosmological sky surveys - ushering in the era of precision cosmology - has been accompanied by ever larger cosmological simulations. The analysis of these simulations, which currently encompass tens of billions of particles and up to a trillion particles in the near future, is often as daunting as carrying out the simulations in the first place. Therefore, the development of very efficient analysis tools combining qualitative and quantitative capabilities is a matter of some urgency. In this paper, we introduce new analysis features implemented within ParaView, a fully parallel, open-source visualization toolkit, to analyze large N-body simulations. A major aspect of ParaView is that it can live and operate on the same machines and utilize the same parallel power as the simulation codes themselves. In addition, data movement is in a serious bottleneck now and will become even more of an issue in the future; an interactive visualization and analysis tool that can handle data in situ is fast becoming essential. The new features in ParaView include particle readers and a very efficient halo finder that identifies friends-of-friends halos and determines common halo properties, including spherical overdensity properties. In combination with many other functionalities already existing within ParaView, such as histogram routines or interfaces to programming languages like Python, this enhanced version enables fast, interactive, and convenient analyses of large cosmological simulations. In addition, development paths are available for future extensions.
Cabozantinib y lenvatinib para cáncer renal
Artículo del blog del NCI sobre la aprobación reciente de la FDA de cabozantinib (Cabometyx®) y de lenvatinib (Lenvima®) para el tratamiento de pacientes cuyo cáncer avanzado de riñón ha evolucionado después de tratamiento con terapias antiangiogénicas.
Leucemia—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento de la leucemia, así como referencias a estudios clínicos, investigación, estadísticas y otros temas relacionados con este tipo de cáncer.
ACUTE TOXICITY OF PARA-NONYLPHENOL TO SALTWATER ANIMALS
?para-Nonylphenol (PNP), a mixture of alkylphenols used in producing nonionic surfactants, is distributed widely in surface waters and aquatic sediments, where it can affect saltwater species. This article describes a database for acute toxicity of PNP derived for calculating a n...
Hacer frente - Para la familia y los amigos
Si usted ayuda a su familiar o amigo durante el tratamiento del cáncer, usted es quien le cuida. Estar al cuidado de una persona con cáncer puede incluir muchas tensiones. Sugerencias para que se cuide usted cuando cuida a otros.
Tumores cerebrales—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento de los tumores cerebrales, así como referencias a estudios clínicos, estadísticas y otros temas relacionados con estos tipos de cáncer.
Linfoma—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento del linfoma, así como referencias a estudios clínicos, investigación, estadísticas y otros temas relacionados con este tipo de cáncer.
Fatiga (PDQ®)—Versión para pacientes
Resumen de información revisada por expertos acerca de la fatiga, una afección caracterizada por extremo cansancio e incapacidad para funcionar por la falta de energía, que a menudo se observa como una complicación del cáncer y su tratamiento.
Delirio (PDQ®)—Versión para pacientes
Resumen de información revisada por expertos acerca del delirio como una complicación del cáncer o su tratamiento. Se tratan enfoques de los cuidados médicos de apoyo y los abordajes farmacológicos para el manejo del delirio.
Mesotelioma maligno—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento y las causas del mesotelioma maligno, así como referencias a estudios clínicos y otros temas relacionados con este tipo de cáncer.
Retinoblastoma—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento del retinoblastoma, así como referencias a estudios clínicos, estadísticas y otros temas relacionados con este tipo de cáncer.
Analyzing and Visualizing Cosmological Simulations with ParaView
NASA Astrophysics Data System (ADS)
Woodring, Jonathan; Heitmann, Katrin; Ahrens, James; Fasel, Patricia; Hsu, Chung-Hsing; Habib, Salman; Pope, Adrian
2011-07-01
The advent of large cosmological sky surveys—ushering in the era of precision cosmology—has been accompanied by ever larger cosmological simulations. The analysis of these simulations, which currently encompass tens of billions of particles and up to a trillion particles in the near future, is often as daunting as carrying out the simulations in the first place. Therefore, the development of very efficient analysis tools combining qualitative and quantitative capabilities is a matter of some urgency. In this paper, we introduce new analysis features implemented within ParaView, a fully parallel, open-source visualization toolkit, to analyze large N-body simulations. A major aspect of ParaView is that it can live and operate on the same machines and utilize the same parallel power as the simulation codes themselves. In addition, data movement is in a serious bottleneck now and will become even more of an issue in the future; an interactive visualization and analysis tool that can handle data in situ is fast becoming essential. The new features in ParaView include particle readers and a very efficient halo finder that identifies friends-of-friends halos and determines common halo properties, including spherical overdensity properties. In combination with many other functionalities already existing within ParaView, such as histogram routines or interfaces to programming languages like Python, this enhanced version enables fast, interactive, and convenient analyses of large cosmological simulations. In addition, development paths are available for future extensions.
Neuroblastoma—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento y los exámenes de detección del neuroblastoma, así como referencias a estudios clínicos, investigación y otros temas relacionados con este tipo de cáncer.
Sistemas Correctores de Campo Para EL Telescopio Cassegrain IAC80
NASA Astrophysics Data System (ADS)
Galan, M. J.; Cobos, F. J.
1987-05-01
El proyecto de instrumentación de mayor importancia que ha tenido el Instituto de Astrofisica de Canarias en los últimos afios ha sido el diseflo y construcción del te1escopio IAC8O. Este requería del esfuerzo con junto en mec´nica, óptica y electrónica, lo que facilitó la estructuración y el crecimiento de los respectivos grupos de trabajo, que posteriormente se integraron en departamentos En su origen (1977), el telescopio IAC80 fue concebido como un sistema clásico tipo Cassegrain, con una razón focal F/i 1.3 para el sistema Casse grain y una razón focal F/20 para el sistema Coudé. Posteriormente, aunque se mantuvo la filosofia de que el sistema básico fuera el F/11.3, se consideró conveniente el diseño de secundarios para razones focales F/16 y F/32, y se eliminó el de F/20. Sin embargo, dada la importancia relativa que un foco estrictamente fotográfico tiene en un telescopio moderno, diseñado básicamente para fotometría fotoeléctrica y con un campo util mínimamente de 40 minutos de arco, se decídió Ilevar a cabo el diseño de un secundario F/8 con un sistema corrector de campo, pero que estuviera formado únicamente por lentes con superficies esféricas para que asl su construcción fuera posible en España ó en México. La creciente utilización de detectores bidimensionales para fines de investigación astron6mica y la viabilidad de que en un futuro cercano éstos tengan un área sensible cada vez mayor, hicieron atractiva la idea de tener diseñado un sistema corrector de campo para el foco primario (F/3), con un campo útil mínimo de un grado, y también con la limitante de que sus componentes tuvieron sólamente supérficies esféricas. Ambos diseños de los sis-temas correctores de campo se llevaron a cabo, en gran medida, como parte de un proyecto de colaboración e intercambio en el área de diseño y evaluación de sistemas ópticos.
DESIGN NOTE: A compact catalytic converter for the production of para-hydrogen
NASA Astrophysics Data System (ADS)
Juarez, A. M.; Cubric, D.; King, G. C.
2002-05-01
The design and operation of a compact converter to produce a constant flow of para-hydrogen from normal hydrogen is described. The converter features a paramagnetic compound (nickel sulfate) that catalyses the conversion of ortho- to para-hydrogen at temperatures of 14-21 K. The converter has been tested by measuring rotationally resolved photoelectron spectra in the para-hydrogen produced. The percentage of the para-hydrogen species in the converted gas was determined to be >97%.
Control del dolor: Apoyo para las personas con cáncer
Contiene información sobre las medicinas contra el dolor para pacientes con cáncer, los planes para controlarlo, cómo hablar con su equipo de atención médica sobre el dolor que usted siente y qué hacer para controlar los efectos físicos y emocionales del
ParA resolvase catalyzes site-specific excision of DNA from the Arabidopsis genome
Technology Transfer Automated Retrieval System (TEKTRAN)
The small serine resolvase ParA from bacterial plasmids RK2 and RP4 catalyzes the recombination of two identical 133 bp recombination sites known as MRS. Previously, we reported that ParA is active in the fission yeast Schizosaccharomyces pombe. In this work, the parA recombinase gene was placed un...
The Regulation of para-Nitrophenol Degradation in Pseudomonas putida DLL-E4
Chen, Qiongzhen; Tu, Hui; Luo, Xue; Zhang, Biying; Huang, Fei; Li, Zhoukun; Wang, Jue; Shen, Wenjing; Wu, Jiale; Cui, Zhongli
2016-01-01
Pseudomonas putida DLL-E4 can efficiently degrade para-nitrophenol and its intermediate metabolite hydroquinone. The regulation of para-nitrophenol degradation was studied, and PNP induced a global change in the transcriptome of P. putida DLL-E4. When grown on PNP, the wild-type strain exhibited significant downregulation of 2912 genes and upregulation of 845 genes, whereas 2927 genes were downregulated and 891 genes upregulated in a pnpR-deleted strain. Genes related to two non-coding RNAs (ins1 and ins2), para-nitrophenol metabolism, the tricarboxylic acid cycle, the outer membrane porin OprB, glucose dehydrogenase Gcd, and carbon catabolite repression were significantly upregulated when cells were grown on para-nitrophenol plus glucose. pnpA, pnpR, pnpC1C2DECX1X2, and pnpR1 are key genes in para-nitrophenol degradation, whereas pnpAb and pnpC1bC2bDbEbCbX1bX2b have lost the ability to degrade para-nitrophenol. Multiple components including transcriptional regulators and other unknown factors regulate para-nitrophenol degradation, and the transcriptional regulation of para-nitrophenol degradation is complex. Glucose utilization was enhanced at early stages of para-nitrophenol supplementation. However, it was inhibited after the total consumption of para-nitrophenol. The addition of glucose led to a significant enhancement in para-nitrophenol degradation and up-regulation in the expression of genes involved in para-nitrophenol degradation and carbon catabolite repression (CCR). It seemed that para-nitrophenol degradation can be regulated by CCR, and relief of CCR might contribute to enhanced para-nitrophenol degradation. In brief, the regulation of para-nitrophenol degradation seems to be controlled by multiple factors and requires further study. PMID:27191401
Para rubber seed oil: new promising unconventional oil for cosmetics.
Lourith, Nattaya; Kanlayavattanakul, Mayuree; Sucontphunt, Apirada; Ondee, Thunnicha
2014-01-01
Para rubber seed was macerated in petroleum ether and n-hexane, individually, for 30 min. The extraction was additionally performed by reflux and soxhlet for 6 h with the same solvent and proportion. Soxhlet extraction by petroleum ether afforded the greatest extractive yield (22.90 ± 0.92%). Although antioxidant activity by means of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay was insignificantly differed in soxhleted (8.90 ± 1.15%) and refluxed (9.02 ± 0.71%) by n-hexane, soxhlet extraction by n-hexane was significantly (p < 0.05) potent scavenged 2,2'-azino-bis(3-ethylbenzothaiazoline)-6-sulfonic acid) or ABTS radical with trolox equivalent antioxidant capacity (TEAC) of 66.54 ± 6.88 mg/100 g oil. This extract was non cytotoxic towards normal human fibroblast cells. In addition, oleic acid and palmitic acid were determined at a greater content than in the seed of para rubber cultivated in Malaysia, although linoleic and stearic acid contents were not differed. This bright yellow extract was further evaluated on other physicochemical characters. The determined specific gravity, refractive index, iodine value, peroxide value and saponification value were in the range of commercialized vegetable oils used as cosmetic raw material. Therefore, Para rubber seed oil is highlighted as the promising ecological ingredient appraisal for cosmetics. Transforming of the seed that is by-product of the important industrial crop of Thailand into cosmetics is encouraged accordingly. PMID:24976614
TELEMEDICINA: UN DESAFÍO PARA AMÉRICA LATINA
Litewka, Sergio
2011-01-01
La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos. Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems. PMID:21625326
ORTHO-PARA SELECTION RULES IN THE GAS-PHASE CHEMISTRY OF INTERSTELLAR AMMONIA
Faure, A.; Hily-Blant, P.; Le Gal, R.; Rist, C.
2013-06-10
The ortho-para chemistry of ammonia in the cold interstellar medium is investigated using a gas-phase chemical network. Branching ratios for the primary reaction chain involved in the formation and destruction of ortho- and para-NH{sub 3} were derived using angular momentum rules based on the conservation of the nuclear spin. We show that the 'anomalous' ortho-to-para ratio of ammonia ({approx}0.7) observed in various interstellar regions is in fact consistent with nuclear spin selection rules in a para-enriched H{sub 2} gas. This ratio is found to be independent of temperature in the range 5-30 K. We also predict an ortho-to-para ratio of {approx}2.3 for NH{sub 2}. We conclude that a low ortho-to-para ratio of H{sub 2} naturally drives the ortho-to-para ratios of nitrogen hydrides below the statistical values.
ParA resolvase catalyzes site-specific excision of DNA from the Arabidopsis genome.
Thomson, James G; Yau, Yuan-Yeu; Blanvillain, Robert; Nunes, Wylla M; Chiniquy, Dawn; Thilmony, Roger; Ow, David W
2009-04-01
The small serine resolvase ParA from bacterial plasmids RK2 and RP4 catalyzes the recombination of two identical 133 bp recombination sites known as MRS. Previously, we reported that ParA is active in the fission yeast Schizosaccharomyces pombe. In this work, the parA recombinase gene was placed under the control of the Arabidopsis OXS3 promoter and introduced into Arabidopsis lines harboring a chromosomally integrated MRS-flanked target. The ParA recombinase excised the MRS-flanked DNA and the excision event was detected in subsequent generations in the absence of ParA, indicating germinal transmission of the excision event. The precise site-specific deletion by the ParA recombination system in planta demonstrates that the ParA recombinase can be used to remove transgenic DNA, such as selectable markers or other introduced transgenes that are no longer desired in the final product. PMID:18704739
Song, Sung Ho; Park, Soo Yeun; Park, Jun Seok; Kim, Hye Jin; Yang, Chun-Seok
2016-01-01
Purpose Treatment of patients with para-aortic lymph node metastasis from colorectal cancer is controversial. The goal of this study was to investigate the technical feasibility of laparoscopic intrarenal para-aortic lymph node dissection in patients with colorectal cancer and clinically suspected para-aortic lymph node dissection. Methods The inclusion criteria for the laparoscopic approach were patients with infrarenal para-aortic lymph node metastasis from colorectal cancer. Patients who had any other distant metastatic lesion or metachronous para-aortic lymph node metastasis were excluded from this study. Perioperative outcomes and survival outcomes were analyzed. Results Between November 2004 and October 2013, 40 patients underwent laparoscopic para-aortic lymph node dissection. The mean operating time was 192.3 ± 68.8 minutes (range, 100-400 minutes) and the mean estimated blood loss was 65.6 ± 52.6 mL (range, 20-210 mL). No patient required open conversion. The postoperative complication rate was 15.0%. Sixteen patients (40.0%) had pathologically positive lymph nodes. In patients with metastatic para-aortic lymph nodes, the 3-year overall survival rate and disease-free survival rate were 65.7% and 40.2%, respectively. Conclusion The results of our study suggest that a laparoscopic approach for patients with colorectal cancer with metastatic para-aortic lymph nodes can be a reasonable option for selected patients. PMID:26793690
Centro para la Salud Mundial del NCI anuncia becas de investigación para tecnologías portátiles
El Centro para la Salud Mundial del NCI (CGH) anunció el otorgamiento de subvenciones que apoyarán el desarrollo y la validación de tecnologías portátiles y de bajo costo para mejorar la detección temprana, el diagnóstico y el tratamiento del cáncer.
Wave Dark Matter and Dwarf Spheroidal Galaxies
NASA Astrophysics Data System (ADS)
Parry, Alan R.
We explore a model of dark matter called wave dark matter (also known as scalar field dark matter and boson stars) which has recently been motivated by a new geometric perspective by Bray. Wave dark matter describes dark matter as a scalar field which satisfies the Einstein-Klein-Gordon equations. These equations rely on a fundamental constant Upsilon (also known as the "mass term'' of the Klein-Gordon equation). Specifically, in this dissertation, we study spherically symmetric wave dark matter and compare these results with observations of dwarf spheroidal galaxies as a first attempt to compare the implications of the theory of wave dark matter with actual observations of dark matter. This includes finding a first estimate of the fundamental constant Upsilon. In the introductory Chapter 1, we present some preliminary background material to define and motivate the study of wave dark matter and describe some of the properties of dwarf spheroidal galaxies. In Chapter 2, we present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. Finally, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. In Chapter 3, we explore spherically symmetric solutions to the Einstein-Klein-Gordon equations, the defining equations of wave dark matter, where the scalar field is of the form f(t, r) = eiotF(r) for some constant o ∈ R and complex-valued function F(r). We show that the corresponding metric is static if and only if F( r) = h(r)eia for some constant alpha ∈ R and real-valued function h(r). We describe the
TELEMEDICINA: UN DESAFÍO PARA AMÉRICA LATINA.
Litewka, Sergio
2005-01-01
La telemedicina es una tendencia creciente en la prestación de los servicios médicos. Aunque la eficacia de esta práctica no ha estado bien establecida, es probable que los países en desarrollo compartirán este nuevo paradigma con los desarrollados. Los defensores de la telemedicina en América Latina sostienen que será una herramienta útil para reducir las disparidades y mejorar la accesibilidad de atención de salud. Aunque América Latina quizá se convierta en un lugar para la investigación e investigación de estos procedimientos, no está claro cómo la telemedicina podría contribuir a mejorar la accesibilidad para las poblaciones desfavorecidas, o coexistir con sistemas de atención de salud públicos crónicamente enfermos.Telemedicine is a growing trend in the provision of medical services. Although the effectiveness of this practice has not been well established, it is likely that developing countries will share this new paradigm with developed ones. Supporters of telemedicine in Latin America maintain that it will be a useful tool for reducing disparities and improving health care accessibility. Although Latin America might become a place for research and investigation of these procedures, it is not clear how telemedicine could contribute to improving accessibility for disadvantaged populations, or coexist with chronically ill-funded public healthcare systems. PMID:21625326
Amazon Land Wars in the South of Para
NASA Technical Reports Server (NTRS)
Simmons, Cynthia S.; Walker, Robert T.; Arima, Eugenio Y.; Aldrich, Stephen P.; Caldas, Marcellus M.
2007-01-01
The South of Para, located in the heart of the Brazilian Amazon, has become notorious for violent land struggle. Although land conflict has a long history in Brazil, and today impacts many parts of the country, violence is most severe and persistent here. The purpose of this article is to examine why. Specifically, we consider how a particular Amazonian place, the so-called South of Para has come to be known as Brazil's most dangerous badland. We begin by considering the predominant literature, which attributes land conflict to the frontier expansion process with intensified struggle emerging in the face of rising property values and demand for private property associated with capitalist development. From this discussion, we distill a concept of the frontier, based on notions of property rights evolution and locational rents. We then empirically test the persistence of place-based violence in the region, and assess the frontier movement through an analysis of transportation costs. The findings from the analyses indicate that the prevalent theorization of frontier violence in Amazonia does little to explain its persistent and pervasive nature in the South of Para. To fill this gap in understanding, we develop an explanation based the geographic conception of place, and we use contentious politics theory heuristically to elucidate the ways in which general processes interact with place specific history to engender a landscape of violence. In so doing, we focus on environmental, cognitive, and relational mechanisms (and implicated structures), and attempt to deploy them in an explanatory framework that allows direct observation of the accumulating layers of the region's tragic history. We end by placing our discussion within a political ecological context, and consider the implications of the Amazon Land War for the environment.
RVA: A Plugin for ParaView 3.14
2015-09-04
RVA is a plugin developed for the 64-bit Windows version of the ParaView 3.14 visualization package. RVA is designed to provide support in the visualization and analysis of complex reservoirs being managed using multi-fluid EOR techniques. RVA, for Reservoir Visualization and Analysis, was developed at the University of Illinois at Urbana-Champaign, with contributions from the Illinois State Geological Survey, Department of Computer Science and National Center for Supercomputing Applications. RVA was designed to utilize and enhance the state-of-the-art visualization capabilities within ParaView, readily allowing joint visualization of geologic framework and reservoir fluid simulation model results. Particular emphasis was placed on enabling visualization and analysis of simulation results highlighting multiple fluid phases, multiple properties for each fluid phase (including flow lines), multiple geologic models and multiple time steps. Additional advanced functionality was provided through the development of custom code to implement data mining capabilities. The built-in functionality of ParaView provides the capacity to process and visualize data sets ranging from small models on local desktop systems to extremely large models created and stored on remote supercomputers. The RVA plugin that we developed and the associated User Manual provide improved functionality through new software tools, and instruction in the use of ParaView-RVA, targeted to petroleum engineers and geologists in industry and research. The RVA web site (http://rva.cs.illinois.edu) provides an overview of functions, and the development web site (https://github.com/shaffer1/RVA) provides ready access to the source code, compiled binaries, user manual, and a suite of demonstration data sets. Key functionality has been included to support a range of reservoirs visualization and analysis needs, including: sophisticated connectivity analysis, cross sections through simulation results between
Spectroscopy of Single Dibenzoterrylene Molecules in para-Dichlorobenzene.
Verhart, Nico R; Müller, Mathias; Orrit, Michel
2016-05-18
We study single dibenzoterrylene (DBT) molecules embedded in 1,4-dichlorobenzene (para-dichlorobenzene, pDCB) at 1.2 K. Due to the relatively low melting point of pDCB (53 °C), this host-guest system can be easily prepared from the molten phase. Narrow linewidths, stable molecular lines and high saturation count rates of single DBT molecules were observed. For this reason, we consider this host-guest system a promising candidate for the study of interactions of single molecules with other small objects such as waveguides or nanoparticles. PMID:26840901
RVA: A Plugin for ParaView 3.14
Energy Science and Technology Software Center (ESTSC)
2015-09-04
RVA is a plugin developed for the 64-bit Windows version of the ParaView 3.14 visualization package. RVA is designed to provide support in the visualization and analysis of complex reservoirs being managed using multi-fluid EOR techniques. RVA, for Reservoir Visualization and Analysis, was developed at the University of Illinois at Urbana-Champaign, with contributions from the Illinois State Geological Survey, Department of Computer Science and National Center for Supercomputing Applications. RVA was designed to utilize andmore » enhance the state-of-the-art visualization capabilities within ParaView, readily allowing joint visualization of geologic framework and reservoir fluid simulation model results. Particular emphasis was placed on enabling visualization and analysis of simulation results highlighting multiple fluid phases, multiple properties for each fluid phase (including flow lines), multiple geologic models and multiple time steps. Additional advanced functionality was provided through the development of custom code to implement data mining capabilities. The built-in functionality of ParaView provides the capacity to process and visualize data sets ranging from small models on local desktop systems to extremely large models created and stored on remote supercomputers. The RVA plugin that we developed and the associated User Manual provide improved functionality through new software tools, and instruction in the use of ParaView-RVA, targeted to petroleum engineers and geologists in industry and research. The RVA web site (http://rva.cs.illinois.edu) provides an overview of functions, and the development web site (https://github.com/shaffer1/RVA) provides ready access to the source code, compiled binaries, user manual, and a suite of demonstration data sets. Key functionality has been included to support a range of reservoirs visualization and analysis needs, including: sophisticated connectivity analysis, cross sections through simulation results
Biodegradation of Para Amino Acetanilide by Halomonas sp. TBZ3
Hajizadeh, Nader; Sefidi Heris, Youssof; Zununi Vahed, Sepideh; Vallipour, Javad; Hejazi, Mohammad Amin; Golabi, Sayyed Mahdi; Asadpour-Zeynali, Karim; Hejazi, Mohammad Saeid
2015-01-01
Background: Aromatic compounds are known as a group of highly persistent environmental pollutants. Halomonas sp. TBZ3 was isolated from the highly salty Urmia Lake of Iran. In this study, characterization of a new Halomonas isolate called Halomonas sp. TBZ3 and its employment for biodegradation of para-amino acetanilide (PAA), as an aromatic environmental pollutant, is described. Objectives: This study aimed to characterize the TBZ3 isolate and to elucidate its ability as a biodegradative agent that decomposes PAA. Materials and Methods: Primarily, DNA-DNA hybridization between TBZ3, Halomonas denitrificans DSM18045T and Halomonas saccharevitans LMG 23976T was carried out. Para-amino acetanilide biodegradation was assessed using spectrophotometry and confirmed by gas chromatography-mass spectroscopy (GC-MS). Parameters effective on biodegradation of PAA were optimized by the Response Surface Methodology (RSM). Results: The DNA-DNA hybridization experiments between isolate TBZ3, H. denitrificans and H. saccharevitans revealed relatedness levels of 57% and 65%, respectively. According to GC-MS results, TBZ3 degrades PAA to benzene, hexyl butanoate, 3-methyl-1-heptanol and hexyl hexanoate. Temperature 32.92°C, pH 6.76, and salinity 14% are the optimum conditions for biodegradation with a confidence level of 95% (at level α = 0.05). Conclusions: According to our results, Halomonas sp. TBZ3 could be considered as a biological agent for bioremediation of PAA and possibly other similar aromatic compounds. PMID:26495103
Kilgore, Matthew B.; Augustin, Megan M.; May, Gregory D.; Crow, John A.; Kutchan, Toni M.
2016-01-01
The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4′-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4′-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot. PMID:26941773
Ortho-para mixing hyperfine interaction in the H2O+ ion and nuclear spin equilibration.
Tanaka, Keiichi; Harada, Kensuke; Oka, Takeshi
2013-10-01
The ortho to para conversion of water ion, H2O(+), due to the interaction between the magnetic moments of the unpaired electron and protons has been theoretically studied to calculate the spontaneous emission lifetime between the ortho- and para-levels. The electron spin-nuclear spin interaction term, Tab(SaΔIb + SbΔIa) mixes ortho (I = 1) and para (I = 0) levels to cause the "forbidden" ortho to para |ΔI| = 1 transition. The mixing term with Tab = 72.0 MHz is 4 orders of magnitude higher for H2O(+) than for its neutral counterpart H2O where the magnetic field interacting with proton spins is by molecular rotation rather than the free electron. The resultant 10(8) increase of ortho to para conversion rate possibly makes the effect of conversion in H2O(+) measurable in laboratories and possibly explains the anomalous ortho to para ratio recently reported by Herschel heterodyne instrument for the far-infrared (HIFI) observation. Results of our calculations show that the ortho ↔ para mixings involving near-degenerate ortho and para levels are high (∼10(-3)), but they tend to occur at high energy levels, ∼300 K. Because of the rapid spontaneous emission, such high levels are not populated in diffuse clouds unless the radiative temperature of the environment is very high. The low-lying 101 (para) and 111 (ortho) levels of H2O(+) are mixed by ∼10(-4) making the spontaneous emission lifetime for the para 101 → ortho 000 transition 520 years and 5200 years depending on the F value of the hyperfine structure. Thus the ortho ↔ para conversion due to the unpaired electron is not likely to seriously affect thermalization of interstellar H2O(+) unless either the radiative temperature is very high or number density of the cloud is very low. PMID:23530629
ParaText : scalable text analysis and visualization.
Dunlavy, Daniel M.; Stanton, Eric T.; Shead, Timothy M.
2010-07-01
Automated analysis of unstructured text documents (e.g., web pages, newswire articles, research publications, business reports) is a key capability for solving important problems in areas including decision making, risk assessment, social network analysis, intelligence analysis, scholarly research and others. However, as data sizes continue to grow in these areas, scalable processing, modeling, and semantic analysis of text collections becomes essential. In this paper, we present the ParaText text analysis engine, a distributed memory software framework for processing, modeling, and analyzing collections of unstructured text documents. Results on several document collections using hundreds of processors are presented to illustrate the exibility, extensibility, and scalability of the the entire process of text modeling from raw data ingestion to application analysis.
Pneumatic protection applied to an airbag for para-gliders
NASA Astrophysics Data System (ADS)
Raievski, V.; Valladas, G.
1998-02-01
We present a theory of pneumatic protection based on the laws of thermodynamics, elasticity and fluid mechanics. A general pneumatic protection system is made up of several communicating compartments, the differences in pressure of the compartments generating a transfer of mass and energy between them. The transfer offers interesting possibilities to improve the performance of the system. An example of this type of protection in aerial sport is the airbag for para-gliders, it is used in this paper to illustrate the theory. As the pressure in the airbag depends uniquely on its volume, the geometric model in the theory can be simplified. Experiments carried out with crash-test dummies equipped with sensors have confirmed the theoretical predictions.
Spectroscopy of Defects in Epitaxially Grown Para-sexiphenyl Nanostructures
NASA Astrophysics Data System (ADS)
Kadashchuk, A.; Schols, S.; Skryshevski, Yu.; Beynik, I.; Teichert, C.; Hernandez-Sosa, G.; Sitter, H.; Andreev, A.; Frank, P.; Winkler, A.
We present a study of steady-state- and time-resolved photoluminescence of para-sexiphenyl (PSP) films on KCl grown by organic molecular beam epitaxy (OMBE). Using different OMBE growth conditions has enabled us to vary greatly the morphology of the PSP crystallites but keeping virtually untouched their chemical structure. By this comparative study we prove that the broad red-shifted emission band has a structure-related origin rather than being due to monomolecular oxidative defects. The relative intensity of the defect emission band observed in the delayed spectra was found to be drastically suppressed in the OMBE-grown films dominated by growth mounds composed of upright standing molecules as opposed to the films consisting of crystallites formed by molecules lying parallel to the substrate.
Para-Hydrogen-Enhanced Gas-Phase Magnetic Resonance Imaging
Bouchard, Louis-S.; Kovtunov, Kirill V.; Burt, Scott R.; Anwar,M. Sabieh; Koptyug, Igor V.; Sagdeev, Renad Z.; Pines, Alexander
2007-02-23
Herein, we demonstrate magnetic resonance imaging (MRI) inthe gas phase using para-hydrogen (p-H2)-induced polarization. A reactantmixture of H2 enriched in the paraspin state and propylene gas is flowedthrough a reactor cell containing a heterogenized catalyst, Wilkinson'scatalyst immobilized on modified silica gel. The hydrogenation product,propane gas, is transferred to the NMR magnet and is spin-polarized as aresult of the ALTADENA (adiabatic longitudinal transport and dissociationengenders net alignment) effect. A polarization enhancement factor of 300relative to thermally polarized gas was observed in 1D1H NMR spectra.Enhancement was also evident in the magnetic resonance images. This isthe first demonstration of imaging a hyperpolarized gaseous productformed in a hydrogenation reaction catalyzed by a supported catalyst.This result may lead to several important applications, includingflow-through porous materials, gas-phase reaction kinetics and adsorptionstudies, and MRI in low fields, all using catalyst-free polarizedfluids.
Nuevos sistemas de frecuencia intermedia para el IAR
NASA Astrophysics Data System (ADS)
Olalde, J. C.; Perilli, D.; Larrarte, J. J.
Se presenta el diagrama en bloques de los nuevos sistemas de Frecuencia Intermedia para los dos radiómetros instalados en el IAR. Entre las características más importantes del sistema podemos mencionar la posibilidad de conectar cualquiera de las dos antenas a los ``backend" disponibles: analizador espectral de alta resolución (META II) de 0,05 Hz, autocorrelador de 1008 canales y contínuo. Se incorporan al sistema nuevos sintetizadores de frecuencia implementados con PLL y la moderna técnica de síntesis digital directa. Por último, el conjunto del sistema es susceptible de ser configurado por las computadoras de adquisición de datos, supervisadas por otra, que entrega el estado de funcionamiento actual y evita la selección de configuraciones incorrectas por parte del usuario.
Wave intensity analysis of para-aortic counterpulsation.
Lu, Pong-Jeu; Yang, Chi-Fu Jeffrey; Wu, Meng-Yu; Hung, Chun-Hao; Chan, Ming-Yao; Hsu, Tzu-Cheng
2012-04-01
Wave intensity analysis (WIA) was used to delineate and maximize the efficacy of a newly developed para-aortic blood pump (PABP). The intra-aortic balloon pump (IABP) was employed as the comparison benchmark. Acute porcine experiments using eight pigs, randomly divided into IABP (n = 4) and PABP (n = 4) groups, were conducted to compare the characteristics of intra- and para-aortic counterpulsation. We measured pressure and velocity with probes installed in the left anterior descending coronary artery and aorta, during and without PABP assistance. Wave intensity for aortic and left coronary waves were derived from pressure and flow measurements with synchronization correction applied. To achieve maximized support efficacy, deflation timings ranging from 25 ms ahead of to 35 ms after the R-wave were tested. Similar to those associated with IABP counterpulsation, the PABP-generated backward-traveling waves predominantly drove aortic and coronary blood flows. However, in contrast with IABP counterpulsation, the nonocclusive nature of the PABP allowed systolic unloading to be delayed into early systole, which resulted in near elimination of coronary blood steal without diminution of systolic left ventricular ejection wave intensities. WIA can elucidate subtleties among different counterpulsatile support means with high sensitivity. Total accelerating wave intensity (TAWI), which was defined as the sum of the time integration of accelerated parts of the positive and negative wave intensities, was used to quantify counterpulsation efficacy. In general, the larger the TAWI gain, the better the counter-pulsatile support efficacy. However, when PABP deflation timings were delayed to after the R-wave, the TAWI was found to be inversely correlated with coronary perfusion. In this delayed deflation timing setting, greater wave cancellation occurred, which led to decreased TAWI but increased coronary perfusion attributed to blood regurgitation reduction. PMID:22227124
The Clearance of Creatinine, Inulin, Para-aminohippurate and Phenosulphothalein in the Cat
Osbaldiston, G. W.; Fuhrman, W.
1970-01-01
Endogenous creatinine, inulin, para-amino-hippurate and phenolsulphothalein clearances for healthy cats are presented. The values for inulin and para-aminohippurate clearances (ml/kg/min) are similar to those for the dog. Creatinine clearance was less than inulin clearance values. Pnenolsulphothalein clearance may be a better index of glomerular rather than tubular function in the cat. PMID:4246836
Chiral phosphoric acid catalyzed asymmetric addition of naphthols to para-quinone methides.
Wong, Yuk Fai; Wang, Zhaobin; Sun, Jianwei
2016-06-28
An asymmetric addition of naphthols to in situ generated para-quinone methides catalyzed by a chiral phosphoric acid is described. A range of useful triarylmethanes can be generated from stable general para-hydroxybenzyl alcohols with good efficiency and enantioselectivity. PMID:26932597
Para-meatal urethral cyst with bladder calculi: A case report and review of the literature.
Patil, Siddangouda B; Patil, Nikhil Ashok; Kundargi, Vinay S; Biradar, Ashok N
2015-01-01
Para-meatal urethral cyst or median raphe cyst of the glans penis is a benign cystic lesion uncommonly encountered in prepubertal age group. Approximately, about 50 cases have been reported till date in the world literature. Herein we report a case of para-meatal urethral cyst concurrent with urinary bladder calculi. PMID:26539378
The parA resolvase performs site-specific genomic excision in Arabidopsis
Technology Transfer Automated Retrieval System (TEKTRAN)
We have designed a site-specific excision detection system in Arabidopsis to study the in planta activity of the small serine recombinase ParA. Using a transient expression assay as well as stable transgenic plant lines, we show that the ParA recombinase is catalytically active and capable of perfo...
Para-meatal urethral cyst with bladder calculi: A case report and review of the literature
Patil, Siddangouda B.; Patil, Nikhil Ashok; Kundargi, Vinay S.; Biradar, Ashok N.
2015-01-01
Para-meatal urethral cyst or median raphe cyst of the glans penis is a benign cystic lesion uncommonly encountered in prepubertal age group. Approximately, about 50 cases have been reported till date in the world literature. Herein we report a case of para-meatal urethral cyst concurrent with urinary bladder calculi. PMID:26539378
Nohynek, Gerhard J; Duche, Daniel; Garrigues, Alexia; Meunier, Pierre-Alain; Toutain, Herve; Leclaire, Jacques
2005-09-15
We investigated the biotransformation of the oxidative arylamine (AA) hair dye ingredients [14C]-para-aminophenol (PAP) and [14C]-para-phenylenediamine (PPD) in reconstructed human epidermis and human hepatocytes. Human epidermis quantitatively transformed PAP to its N-acetylated derivative (APAP), whereas hepatocytes transformed PAP to sulfate or glucuronic acid conjugates of APAP or PAP as well as free APAP. Epidermis and hepatocytes converted PPD to N-mono- (MAPPD) and N,N'-di-acetylated (DAPPD) derivatives. At higher concentrations of PPD (250-1000 microM), epidermis or hepatocytes produced more of the MAPPD, whereas concentrations below 250 microM and lower favoured formation of the DAPPD metabolite. When compared with epidermis, human hepatocytes had a three-fold or eight-fold greater capacity for generation of MAPPD or DAPPD, respectively. No evidence of transformation of PAP or PPD to N-hydroxylated derivatives was found in epidermis or hepatocytes. Our results suggest that (i) after dermal absorption of PAP or PPD, humans are systemically exposed to acetylated derivatives; (ii) current in vitro skin absorption studies may be inadapated for determination of human systemic exposure to AAs due to reduced or absent metabolic capacity of non-viable skin; (iii) due to qualitative differences between dermal and hepatic metabolism, oral toxicity studies may be unsuited for the hazard assessment of dermal exposure to AAs; and (iv) use of induced rodent liver S9 metabolic activation systems for in vitro genotoxicity studies may produce misleading results on the hazard of human dermal exposure to AAs. In conclusion, our data support the growing evidence that AAs are transformed in human skin and suggest that current practices of safety assessment of AAs should take these findings into account. PMID:15890478
ERIC Educational Resources Information Center
Raval, Harini; McKenney, Susan; Pieters, Jules
2012-01-01
The appointment of para-professionals to overcome skill shortages and/or make efficient use of expensive resources is well established in both developing and developed countries. The present research concerns para-teachers in India. The literature on para-teachers is dominated by training for special needs settings, largely in developed societies.…
Bourne, Godfrey R; Breden, Felix; Allen, Teresa C
2003-09-01
The first results of female preference and chosen male mating success in a new model organism, the pentamorphic livebearing fish, Poecilia parae, are presented. Poecilia parae is a relative of the guppy, P. reticulata, and is assumed to have similar reproductive behavior. We tested the hypothesis that P. parae females, like female guppies, prefer carotenoid colored males as mates. Here we show that the time a female spent with males was significantly greater for carotenoid coloration in red and yellow melanzona, but time with these two morphs did not differ. The preferred red and yellow males mated significantly more often with their choosing females than did the non-preferred blue and parae males. The few blue melanzona and parae males that mated did so without performing courtship displays. Some females mated with all phenotypes including immaculata males during open group trials. Female P. parae clearly preferred males with carotenoid coloration, thereby corroborating the hypothesis. Alternative male mating tactics by blue melanzona, parae, and immaculata morphs and promiscuous mating by females also resembled features of reproductive behaviors exhibited by guppies. PMID:14504782
Quantum fluctuations increase the self-diffusive motion of para-hydrogen in narrow carbon nanotubes.
Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester
2011-05-28
Quantum fluctuations significantly increase the self-diffusive motion of para-hydrogen adsorbed in narrow carbon nanotubes at 30 K comparing to its classical counterpart. Rigorous Feynman's path integral calculations reveal that self-diffusive motion of para-hydrogen in a narrow (6,6) carbon nanotube at 30 K and pore densities below ∼29 mmol cm(-3) is one order of magnitude faster than the classical counterpart. We find that the zero-point energy and tunneling significantly smoothed out the free energy landscape of para-hydrogen molecules adsorbed in a narrow (6,6) carbon nanotube. This promotes a delocalization of the confined para-hydrogen at 30 K (i.e., population of unclassical paths due to quantum effects). Contrary the self-diffusive motion of classical para-hydrogen molecules in a narrow (6,6) carbon nanotube at 30 K is very slow. This is because classical para-hydrogen molecules undergo highly correlated movement when their collision diameter approached the carbon nanotube size (i.e., anomalous diffusion in quasi-one dimensional pores). On the basis of current results we predict that narrow single-walled carbon nanotubes are promising nanoporous molecular sieves being able to separate para-hydrogen molecules from mixtures of classical particles at cryogenic temperatures. PMID:21503294
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, F.H.; Moore, J.C.
1999-05-25
A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, Frances H.; Moore, Jeffrey C.
1999-01-01
A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, Frances H.; Moore, Jeffrey C.
1998-01-01
A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.
Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media
Arnold, F.H.; Moore, J.C.
1998-04-21
A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases. These enzymes exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.
Para-hydrogen induced polarization in heterogeneous hydrogenationreactions
Koptyug, Igor V.; Kovtunov, Kirill; Burt, Scott R.; Anwar, M.Sabieh; Hilty, Christian; Han, Song-I; Pines, Alexander; Sagdeev, Renad Z.
2007-01-31
We demonstrate the creation and observation ofpara-hydrogen-induced polarization in heterogeneous hydrogenationreactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on eithermodified silica gel or a polymer, is shown to hydrogenate styrene intoethylbenzene and to produce enhanced spin polarizations, observed throughNMR, when the reaction was performed with H2 gas enriched in the paraspinisomer. Furthermore, gaseous phase para-hydrogenation of propylene topropane with two catalysts, the Wilkinson's catalyst supported onmodified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene;sulfos) - O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstratesheterogeneous catalytic conversion resulting in large spin polarizations.These experiments serve as a direct verification of the mechanism ofheterogeneous hydrogenation reactions involving immobilized metalcomplexes and can be potentially developed into a practical tool forproducing catalyst-free fluids with highly polarized nuclear spins for abroad range of hyperpolarized NMR and MRI applications.
DYNA3D/ParaDyn Regression Test Suite Inventory
Lin, J I
2011-01-25
The following table constitutes an initial assessment of feature coverage across the regression test suite used for DYNA3D and ParaDyn. It documents the regression test suite at the time of production release 10.1 in September 2010. The columns of the table represent groupings of functionalities, e.g., material models. Each problem in the test suite is represented by a row in the table. All features exercised by the problem are denoted by a check mark in the corresponding column. The definition of ''feature'' has not been subdivided to its smallest unit of user input, e.g., algorithmic parameters specific to a particular type of contact surface. This represents a judgment to provide code developers and users a reasonable impression of feature coverage without expanding the width of the table by several multiples. All regression testing is run in parallel, typically with eight processors. Many are strictly regression tests acting as a check that the codes continue to produce adequately repeatable results as development unfolds, compilers change and platforms are replaced. A subset of the tests represents true verification problems that have been checked against analytical or other benchmark solutions. Users are welcomed to submit documented problems for inclusion in the test suite, especially if they are heavily exercising, and dependent upon, features that are currently underrepresented.
Anise oil as para-methoxyamphetamine (PMA) precursor.
Waumans, Dieter; Bruneel, Noël; Tytgat, Jan
2003-04-23
These days, MDMA is one of the most popular drugs of abuse. Due to its illegality, MDMA and its chemical precursors are watched by governmental organizations in many countries. To avoid conflicts with legal instances, underground chemists have tried to market several new unregulated amphetamine analogues, such as 4-MTA. Para-methoxyamphetamine (PMA), on the other hand, is regulated by law but its precursors are easily obtained since they are cheap and unwatched. This article presents such a case, namely the large scale synthesis of PMA using anethole, a main constituent of anise oil, as precursor. Anethole has been converted to its phenyl acetone analogue via peracid oxidation, while PMA itself has been synthesized using this ketone as precursor in the Leuckart synthesis. The synthesis of PMA using anethole as starting product has been investigated applying GC/MS and GC-HSPME/MS techniques, hereby discovering new specific (4-methoxyphenol) and already identified synthesis impurities (4-methyl-5-(4-methoxyphenyl)pyrimidine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzyl methyl ketimine, 1-(4-methoxyphenyl)-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, 1-(4-methoxyphenyl)-N-methyl-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzaldimine). The new impurity 4-methoxyphenol is specific for the application of a peracid oxidation method where anethole is used as precursor. PMID:12742705
Metabolism of para-aminophenol by rat hepatocytes.
Yan, Z; Nikelly, J G; Killmer, L; Tarloff, J B
2000-08-01
Autoxidation of para-aminophenol (PAP) has been proposed to account for the selective nephrotoxicity of this compound. However, other studies suggest that hepatic metabolites of PAP rather than the parent compound may be responsible for renal damage. These studies were designed to investigate PAP metabolism in isolated hepatocytes. We synthesized several proposed metabolites for analysis by HPLC/mass spectrometry and compared those results with HPLC/mass spectrometric analyses of metabolites found after incubating hepatocytes with PAP. Hepatocytes prepared from male Sprague-Dawley rats were incubated in Krebs-Henseleit buffer at 37 degrees C for 5 h with 2.3 mM PAP under an atmosphere of 5% CO2/95% O2. Aliquots were withdrawn at 0.1 h of incubation and then hourly through 5 h of incubation. Reactions were terminated by the addition of acetonitrile. Hepatocyte viability was unaltered with PAP present in the incubation medium. We found that hepatocytes converted PAP to two major metabolites (PAP-GSH conjugates and PAP-N-acetylcysteine conjugates) and several minor metabolites [PAP-O-glucuronide, acetaminophen (APAP), APAP-O-glucuronide, APAP-GSH conjugates, and 4-hydroxyformanilide]. Preincubating hepatoyctes with 1-aminobenzotriazole, an inhibitor of cytochromes P450, did not alter the pattern of PAP metabolism. In conclusion, we found that PAP was metabolized in hepatocytes predominantly to PAP-GSH conjugates and PAP-N-acetylcysteine conjugates in sufficient quantities to account for the nephrotoxicity of PAP. PMID:10901695
Conformation of ionizable poly Para phenylene ethynylene in dilute solutions
Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; Grest, Gary S.
2015-11-03
The conformation of dinonyl poly para phenylene ethynylenes (PPEs) with carboxylate side chains, equilibrated in solvents of different quality is studied using molecular dynamics simulations. PPEs are of interest because of their tunable electro-optical properties, chemical diversity, and functionality which are essential in wide range of applications. The polymer conformation determines the conjugation length and their assembly mode and affects electro-optical properties which are critical in their current and potential uses. The current study investigates the effect of carboxylate fraction on PPEs side chains on the conformation of chains in the dilute limit, in solvents of different quality. The dinonylmore » PPE chains are modeled atomistically, where the solvents are modeled both implicitly and explicitly. Dinonyl PPEs maintained a stretched out conformation up to a carboxylate fraction f of 0.7 in all solvents studied. The nonyl side chains are extended and oriented away from the PPE backbone in toluene and in implicit good solvent whereas in water and implicit poor solvent, the nonyl side chains are collapsed towards the PPE backbone. Thus, rotation around the aromatic ring is fast and no long range correlations are seen within the backbone.« less
Evidence for para dechlorination of polychlorobiphenyls by methanogenic bacteria
Ye, D.; Quensen, J.F.; Tiedje, J.M.
1995-06-01
When microorganisms eluted from upper Hudson River sediment were cultured without any substrate except polychlorobiphenyl (PCB)-free Hudson River sediment, methane formation was the terminal step of the anaerobic food chain. In sediments containing Aroclor 1242, addition of eubacterium-inhibiting antibiotics, which should have directly inhibited fermentative bacteria and thereby should have indirectly inhibited methanogens, resulted in no dechlorination activity or methane production. However, when substrates for methanogenic bacteria were provided along with the antibiotics (to free the methanogens from dependence on eubacteria), concomitant methane production and dechlorination of PCBs were observed. The dechlorination of Aroclor 1242 was from the para positions, a pattern distinctly different from, and more limited than, the pattern observed with untreated or pasteurized inocula. Both methane production and dechlorination in cultures amended with antibiotics plus methanogenic substrates were inhibited by 2-bromoethanesulfonic acid. These results suggest that the methanogenic bacteria are among the physiological groups capable of anaerobic dechlorination of PCBs, but that the dechlorination observed with methanogenic bacteria is less extensive than the dechlorination observed with more complex anaerobic consortia. 27 refs., 5 figs., 1 tab.
Uninfected Para-Anastomotic Aneurysms after Infrarenal Aortic Grafting
Nano, Giovanni; Cusmai, Francesco; Ramponi, Fabio; Stegher, Silvia; Dell'Aglio, Daniela; Malacrida, Giovanni; Tealdi, Domenico G.
2009-01-01
Purpose This single-institution retrospective review examines the management of uninfected para-anastomotic aneurysms of the abdominal aorta (PAAA), developed after infrarenal grafting. Materials and Methods From October 1979 to November 2005, 31 PAAA were observed in our Department. Twenty-six uninfected PAAA of degenerative etiology, including 24 false and 2 true aneurysms, were candidates for intervention and retrospectively included in our database for management and outcome evaluation. Six (23%) patients were treated as emergencies. Surgery included tube graft interposition (n = 12), new reconstruction (n = 8), and graft removal with extra-anatomic bypass (n = 3). Endovascular management (n = 3) consisted of free-flow tube endografts. Results The mortality rate among the elective and emergency cases was 5% and 66.6%, respectively (p = 0.005). The morbidity rate in elective cases was 57.8%, whereas 75% in emergency cases (p = 0.99). The survival rate during the follow-up was significantly higher for elective cases than for emergency cases. Conclusion Uninfected PAAA is a late complication of aortic grafting, tends to evolve silently and is difficult to diagnose. The prevalence is underestimated and increases with time since surgery. The mortality rate is higher among patients treated as an emergency than among patients who undergo elective surgery, therefore, elective treatment and aggressive management in the case of pseudoaneurysm are the keys to obtain a good outcome. Endovascular treatment could reduce mortality. Patients who undergo infrarenal aortic grafting require life-long surveillance after surgery. PMID:19430556
Sélley, Eszter; Kun, Szilárd; Kürthy, Mária; Kovács, Tibor; Wittmann, István; Molnár, Gergo A
2015-01-01
Former data of our workgroup indicated that the accumulation of oxidized amino acids (meta- and ortho-tyrosine) due to oxidative stress may play an important role in the impaired insulininduced vasoactive properties of different arterial segments. There are evidences, that incorporation of these amino acids into cellular proteins leads to certain hormonal resistances, which might be restored by supplementation with the physiologic isoform, para-tyrosine. Rats in the control group were kept on a regular diet, rats in the cholesterol-fed group received high-fat diet, while the third group of rats received high-fat diet with para-tyrosine supplementation for 16 weeks. Plasma cholesterol level was significantly higher in the cholesterol-fed group, while the level of cholesterol in the cholesterol+para-tyrosine group did not differ significantly from that of the controls. Plasma level of insulin after glucose stimulation was decreased in the cholesterol-fed group, while that in the para-tyrosine supplemented group did not differ significantly from the controls. Vascular para-, meta- and ortho-tyrosine content was measured with HPLC. Elevated vascular meta-tyrosine/para-tyrosine ratio of cholesterol fed rats could be avoided by para-tyrosine supplementation. Vascular response of the thoracic aorta to insulin and liraglutide was assessed by a DMT multi-myograph. Cholesterol feeding resulted in vascular insulin-and liraglutide resistance, which was restored by para-tyrosine supplementation. Incorporation of the oxidative stress induced pathological tyrosine isoforms leads to vascular-hormone-resistances. We show that the physiological amino acid para-tyrosine is capable of restoring hypercholesterolemia-induced increased meta-tyrosine content of the vascular wall, thus attenuating functional vascular damage. PMID:26202368
Endovascular Treatment of a Ruptured Para-Anastomotic Aneurysm of the Abdominal Aorta
Sfyroeras, Giorgos S.; Lioupis, Christos Bessias, Nikolaos; Maras, Dimitris; Pomoni, Maria; Andrikopoulos, Vassilios
2008-07-15
We report a case of a ruptured para-anastomotic aortic aneurysm treated with implantation of a bifurcated stent-graft. A 72-year-old patient, who had undergone aortobifemoral bypass for aortoiliac occlusive disease 16 years ago, presented with a ruptured para-anastomotic aortic aneurysm. A bifurcated stent-graft was successfully deployed into the old bifurcated graft. This is the first report of a bifurcated stent-graft being placed through an 'end-to-side' anastomosed old aortobifemoral graft. Endovascular treatment of ruptured para-anastomotic aortic aneurysms can be accomplished successfully, avoiding open surgery which is associated with increased mortality and morbidity.
Measurement of the formaldehyde ortho to para ratio in three molecular clouds
NASA Technical Reports Server (NTRS)
Kahane, C.; Lucas, R.; Frerking, M. A.; Langer, W. D.; Encrenaz, P.
1984-01-01
Observations of ortho and para H2CO in two types of clouds, a warm cloud (Orion A) and two cold clouds (L183 and TMC1), are presented. The ortho to para ratio in Orion deduced from the H2(C-13)O data is about three, while that for TMC1 is about one and that for L183 is 1-2. The former value is in agreement with the value calculated from chemical models of ortho and para H2CO production. The values for the cold clouds are consistent with thermal equilibrium at a temperature slightly smaller than 10 K.
ERIC Educational Resources Information Center
California State Polytechnic Univ., Pomona.
The Intermediate Science Curriculum Study Spanish language science instruction manual for the intermediate grades focuses on energy of many types. The soft bound volume uses self-pacing and individualized learning to guide the students through a series of experiments. Basically, the students are asked to think about what they do and see, evaluate…
Management of large para-esophageal hiatal hernias.
Collet, D; Luc, G; Chiche, L
2013-12-01
Para-esophageal hernias are relatively rare and typically occur in elderly patients. The various presenting symptoms are non-specific and often occur in combination. These include symptoms of gastro-esophageal reflux (GERD) in 26 to 70% of cases, microcytic anemia in 17 to 47%, and respiratory symptoms in 9 to 59%. Respiratory symptoms are not completely resolved by surgical intervention. Acute complications such as gastric volvulus with incarceration or strangulation are rare (estimated incidence of 1.2% per patient per year) but gastric ischemia leading to perforation is the main cause of mortality. Only patients with symptomatic hernias should undergo surgery. Prophylactic repair to prevent acute incarceration should only be undertaken in patients younger than 75 in good condition; surgical indications must be discussed individually beyond this age. The laparoscopic approach is now generally accepted. Resection of the hernia sac is associated with a lower incidence of recurrence. Repair of the hiatus can be reinforced with prosthetic material (either synthetic or biologic), but the benefit of prosthetic repair has not been clearly shown. Results of prosthetic reinforcement vary in different studies; it has been variably associated with four times fewer recurrences or with no measurable difference. A Collis type gastroplasty may be useful to lengthen a foreshortened esophagus, but no objective criteria have been defined to support this approach. The anatomic recurrence rate can be as high as 60% at 12years. But most recurrences are asymptomatic and do not affect the quality of life index. It therefore seems more appropriate to evaluate functional results and quality of life measures rather than to gauge success by a strict evaluation of anatomic hernia reduction. PMID:24060742
Successful Mnemonics for "por"/"para" and Affirmative Commands with Pronouns.
ERIC Educational Resources Information Center
Mason, Keith
1992-01-01
Two mnemonic devices, "4A Rule" and "PERFECT," are described to simplify the learning of two grammar points: the placement of object pronouns with respect to commands and the distinction between "por" and "para." (five references) (LB)
Tumores carcinoides gastrointestinales—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento del tumor carcinoide gastrointestinal, así como referencias a estudios clínicos y otros temas relacionados.
Carcinoma de tumor primario desconocido—Versión para profesionales de salud
Información del Instituto Nacional del Cáncer para profesionales de salud sobre el tratamiento del carcinoma de tumor primario desconocido, así como referencias a estudios clínicos y otros temas relacionados.
Efficient ortho-para conversion of H2 on interstellar grain surfaces
NASA Astrophysics Data System (ADS)
Bron, Emeric; Le Petit, Franck; Le Bourlot, Jacques
2016-04-01
Context. Fast surface conversion between ortho- and para-H2 has been observed in laboratory studies, and it has been proposed that this mechanism plays a role in the control of the ortho-para ratio in the interstellar medium. Observations of rotational lines of H2 in photo-dissociation regions (PDRs) have indeed found significantly lower ortho-para ratios than expected at equilibrium. The mechanisms controlling the balance of the ortho-para ratio in the interstellar medium thus remain incompletely understood, while this ratio can affect the thermodynamical properties of the gas (equation of state, cooling function). Aims: We aim to build an accurate model of ortho-para conversion on dust surfaces based on the most recent experimental and theoretical results, and to validate it by comparison to observations of H2 rotational lines in PDRs. Methods: We propose a statistical model of ortho-para conversion on dust grains with fluctuating dust temperatures. It is based on a master equation approach. This computation is then coupled to full PDR models and compared to PDR observations. Results: We show that the observations of rotational H2 lines indicate a high conversion efficiency on dust grains and that this high efficiency can be accounted for if taking dust temperature fluctuations into account with our statistical model of surface conversion. Simpler models that neglect the dust temperature fluctuations do not reach the high efficiency deduced from the observations. Moreover, this high efficiency induced by dust temperature fluctuations is very insensitive to the values of the model's microphysical parameters. Conclusions: Ortho-para conversion on grains is thus an efficient mechanism in most astrophysical conditions and can play a significant role in controlling the ortho-para ratio.
Pakish, Janelle; Soliman, Pamela T.; Frumovitz, Michael; Westin, Shannon N.; Schmeler, Kathleen M.; dos Reis, Ricardo; Munsell, Mark F.; Ramirez, Pedro T.
2014-01-01
Objective The objective of our study was to compare the surgical outcomes of extraperitoneal laparoscopic, transperitoneal laparoscopic, and robotic transperitoneal para-aortic lymphadenectomy in endometrial cancer staging. Methods A retrospective review was performed from January 2007 to November 2012. Three groups were compared: extraperitoneal laparoscopic para-aortic lymphadenectomy and robotic hysterectomy and pelvic lymphadenectomy (“extraperitoneal group”; N=34); laparoscopic hysterectomy and transperitoneal pelvic and para-aortic lymphadenectomy (“transperitoneal laparoscopic group”; N=108); and robotic hysterectomy and transperitoneal pelvic and para-aortic lymphadenectomy (“transperitoneal robotic group”; N=52). Fisher’s exact test and Kruskal-Wallis test were used for statistical analysis, and statistical significance was defined as P< 0.05. Results Median number of para-aortic lymph nodes obtained was higher in the extraperitoneal group than in the transperitoneal laparoscopic and robotic groups (10, 5, and 4.5 nodes, respectively; P<0.001). Among patients with BMI <35 kg/m2, the median number of para-aortic nodes harvested was higher in the extraperitoneal group than in the transperitoneal laparoscopic and robotic groups (9, 4, and 5 nodes, respectively; P<0.01). The same pattern was observed among patients with BMI ≥35 kg/m2 (10, 6, and 3 nodes, respectively) (P=0.001). There was no significant difference in median estimated blood loss between the extraperitoneal group and either the transperitoneal laparoscopic group (100 vs. 112.5 mL; P=0.06) or the transperitoneal robotic group (100 vs. 67.5 mL; P=0.23). Conclusion Extraperitoneal laparoscopic para-aortic lymphadenectomy resulted in a higher number of para-aortic lymph nodes removed than transperitoneal laparoscopic or robotic lymphadenectomy. The extraperitoneal approach should be considered for endometrial cancer staging. PMID:24361579
NASA Astrophysics Data System (ADS)
Tanaka, Keiichi; Hayashi, Masato; Ohtsuki, Mitsuhiko; Harada, Kensuke; Tanaka, Takehiko
2010-06-01
Ortho-para mixing interaction due to the coupling of nuclear and electron spins was detected for the first time by millimeter-wave spectroscopy of deuterated vinyl radicals, H_2CCD and D_2CCD, of which the ground states are split by the tunneling motion of the α deuteron into two components 0^+ and 0^-, whose separations have been determined to be Δ E_0 = 1186.644(16) and 771.978(18) MHz, respectively. The observed tunneling-rotation spectra are significantly perturbed by the othro-para mixing interaction expressed by < 0^± |H'|0^mprangle = (δ aF(β)/2) S \\cdot(I_β 1-I_β 2), where I_β 1 and I_β 2 are spins of the two hydrogen nuclei in the β position and S is the electron spin, which connects rotational levels in the 0^+ and 0^- states, one being an ortho level and the other a para level. The δ aF(β) constants for H_2CCD and D_2CCD have been determined to be 68.06(53) and 10.63(94) MHz, respectively, consistent each other within the isotopic mass relation. The othro and para states are mixed by about 0.097% and 0.0123% due to this interaction. The δ aF constant for H_2CCH should be similar to that for H_2CCD because of the same probability density of the unpaired electron at the β protons, but could not be determined independently in our previous study. It is because the mixing of para- and ortho-levels of about 0.00044% is much smaller than that for H_2CCD due to the large tunneling splitting of Δ E_0=16271.8429(59) MHz. The rate constant of para to ortho (I_β = 0 → 1) conversion is predicted as 1.2× 10^5 s-1 torr-1 for H_2CCD, suggesting extremely rapid mutual conversion between ortho and para nuclear spin isomers of H_2CCD, which is more than 106 times faster compared with that in closed shell molecules such as H_2CO and H_2CCH_2. K. Tanaka, M. Hayashi, M. Ohtsuki, K. Harada, T. Tanaka, J. Chem. Phys., 131, 111101 (2009). K. Tanaka, M. Toshimitsu, K. Harada, T. Tanaka, J. Chem. Phys., 120, 3604 (2004).
Roka, Eszter; Vecsernyes, Miklos; Bacskay, Ildiko; Félix, Caroline; Rhimi, Moez; Coleman, Anthony W; Perret, Florent
2015-06-01
The passage of Lucifer Yellow across the Caco-2 intestinal model membrane has been studied for the para-sulphonato-calix[n]arenes, the results show that para-sulphonato-calix[4]arene and para-sulphonato-calix[8]arene activate membrane passage when used simultaneously with a transport probe, Lucifer Yellow, whereas para-sulphonato-calix[6]arene has no effect. PMID:25958962
Space-time curvature signatures in Bose-Einstein condensates
NASA Astrophysics Data System (ADS)
Matos, Tonatiuh; Gomez, Eduardo
2015-05-01
We derive a generalized Gross-Pitaevski (GP) equation for a Bose Einstein Condensate (BEC) immersed in a weak gravitational field starting from the covariant Complex Klein-Gordon field in a curved space-time. We compare it with the traditional GP equation where the gravitational field is added by hand as an external potential. We show that there is a small difference of order gz/c2 between them that could be measured in the future using Bose-Einstein Condensates. This represents the next order correction to the Newtonian gravity in a curved space-time.
Relativity and Quantum Mechanics
Braendas, Erkki J.
2007-12-26
The old dilemma of quantum mechanics versus the theory of relativity is reconsidered via a first principles relativistically invariant theory. By analytic extension of quantum mechanics into the complex plane one may (i) include dynamical features such as time- and length-scales and (ii) examine the possibility and flexibility of so-called general Jordan block formations. The present viewpoint asks for a new perspective on the age-old problem of quantum mechanics versus the theory of relativity. To bring these ideas together, we will establish the relation with the Klein-Gordon-Dirac relativistic theory and confirm some dynamical features of both the special and the general relativity theory.
MAPLE Procedures For Boson Fields System On Curved Space - Time
Murariu, Gabriel
2007-04-23
Systems of interacting boson fields are an important subject in the last years. From the problem of dark matter to boson stars' study, boson fields are involved. In the general configuration, it is considered a Klein-Gordon-Maxwell-Einstein fields system for a complex scalar field minimally coupled to a gravitational one. The necessity of studying a larger number of space-time configurations and the huge volume of computations for each particular situation are some reasons for building a MAPLE procedures set for this kind of systems.
Discrete-time quantum walks: Continuous limit and symmetries
Molfetta, G. di; Debbasch, F.
2012-12-15
The continuous limit of one-dimensional discrete-time quantum walks with time-and space-dependent coefficients is investigated. A given quantum walk does not generally admit a continuous limit but some families (1-jets) of quantum walks do. All families (1-jets) admitting a continuous limit are identified. The continuous limit is described by a Dirac-like equation or, alternately, a couple of Klein-Gordon equations. Variational principles leading to these equations are also discussed, together with local invariance properties.
The Invariant Operator Theory, and the Unification of the Fundamental Interactions
NASA Astrophysics Data System (ADS)
Nduka, Amagh
2002-10-01
This paper established explicitly and unambiguously that the Invariant Operator Theory is the most general physical theory that can be constructed in a pseudo-euclidean (space-time) background. Specifically, we show that the field theories of Isaac Newton, Clarke Maxwell, Erwin Schrodinger, Klein-Gordon, and Paul A. M. Dirac are mere derivatives of the new Theory. Finally we discuss the unification of the fundamental interactions. We find that the NEW Physics has succesfully resolved all the outstanding problems of Physics, with the exception of the problem of mass.
Octonic Gravitational Field Equations
NASA Astrophysics Data System (ADS)
Demir, Süleyman; Tanişli, Murat; Tolan, Tülay
2013-08-01
Generalized field equations of linear gravity are formulated on the basis of octons. When compared to the other eight-component noncommutative hypercomplex number systems, it is demonstrated that associative octons with scalar, pseudoscalar, pseudovector and vector values present a convenient and capable tool to describe the Maxwell-Proca-like field equations of gravitoelectromagnetism in a compact and simple way. Introducing massive graviton and gravitomagnetic monopole terms, the generalized gravitational wave equation and Klein-Gordon equation for linear gravity are also developed.
New scale-relativistic derivations of Pauli and Dirac equations
NASA Astrophysics Data System (ADS)
Hammad, F.
2008-02-01
In scale relativity, quantum mechanics is recovered by transcribing the classical equations of motion to fractal spaces and demanding, as dictated by the principle of scale relativity, that the form of these equations be preserved. In the framework of this theory, however, the form of the classical energy equations both in the relativistic and nonrelativistic cases are not preserved. Aiming to get full covariance, i.e., to restore to these equations their classical forms, we show that the scale-relativistic form of the Schrödinger equation yields the Pauli equation, whilst the Pissondes's scale-relativistic form of the Klein-Gordon equation gives the Dirac equation.
Dielectric permittivity of quantum plasma. Part II
NASA Astrophysics Data System (ADS)
Bobylev, Yu. V.; Kuzelev, M. V.
2014-05-01
The transverse and longitudinal dielectric permittivities of isotropic quantum plasma are calculated in the quantum plasma models based on the Dirac and Pauli equations. The dispersion relations for transverse-longitudinal waves in quantum particle beams are derived. Relativistic longitudinal and transverse waves in cold isotropic quantum plasma in models based on the Klein-Gordon and Dirac equations, as well as spin waves in the model based on the Pauli equation, are considered. Conditions for wave-particle resonance interactions in relativistic quantum plasma are analyzed.