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1

Wave-function functionals  

SciTech Connect

We extend our prior work on the construction of variational wave functions {psi} that are functionals of functions {chi}:{psi}={psi}[{chi}] rather than simply being functions. In this manner, the space of variations is expanded over those of traditional variational wave functions. In this article we perform the constrained search over the functions {chi} chosen such that the functional {psi}[{chi}] satisfies simultaneously the constraints of normalization and the exact expectation value of an arbitrary single- or two-particle Hermitian operator, while also leading to a rigorous upper bound to the energy. As such the wave function functional is accurate not only in the region of space in which the principal contributions to the energy arise but also in the other region of the space represented by the Hermitian operator. To demonstrate the efficacy of these ideas, we apply such a constrained search to the ground state of the negative ion of atomic hydrogen H{sup -}, the helium atom He, and its positive ions Li{sup +} and Be{sup 2+}. The operators W whose expectations are obtained exactly are the sum of the single-particle operators W={Sigma}{sub i}r{sub i}{sup n},n=-2,-1,1,2, W={Sigma}{sub i{delta}}(r{sub i}), W=-(1/2){Sigma}{sub i{nabla}i}{sup 2}, and the two-particle operators W={Sigma}{sub n}u{sup n},n=-2,-1,1,2, where u=|r{sub i}-r{sub j}|. Comparisons with the method of Lagrangian multipliers and of other constructions of wave-function functionals are made. Finally, we present further insights into the construction of wave-function functionals by studying a previously proposed construction of functionals {psi}[{chi}] that lead to the exact expectation of arbitrary Hermitian operators. We discover that analogous to the solutions of the Schroedinger equation, there exist {psi}[{chi}] that are unphysical in that they lead to singular values for the expectations. We also explain the origin of the singularity.

Pan Xiaoyin; Slamet, Marlina; Sahni, Viraht [Faculty of Science, Ningbo University, Ningbo, 315211 (China); Sacred Heart University, Fairfield, Connecticut 06825 (United States); Brooklyn College and The Graduate School of the City University of New York, New York, New York 10016 (United States)

2010-04-15

2

Wave Function Plotter Model  

NSDL National Science Digital Library

The Ejs Wave Function Plotter model displays a one-dimensional wave function u(x,t) depicting a disturbance at position x and time t. The disturbance can be mass density, pressure, or electric field depending on the physical context. The default wave function is sinusoidal but any other analytic function can be entered in the text box. The number of sampling points can also be changed. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Wave Function Plotter model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_osc_chains_WaveFunctionPlotter.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for Newtonian mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-05

3

Adaptive multiconfigurational wave functions  

SciTech Connect

A method is suggested to build simple multiconfigurational wave functions specified uniquely by an energy cutoff ?. These are constructed from a model space containing determinants with energy relative to that of the most stable determinant no greater than ?. The resulting ?-CI wave function is adaptive, being able to represent both single-reference and multireference electronic states. We also consider a more compact wave function parameterization (?+SD-CI), which is based on a small ?-CI reference and adds a selection of all the singly and doubly excited determinants generated from it. We report two heuristic algorithms to build ?-CI wave functions. The first is based on an approximate prescreening of the full configuration interaction space, while the second performs a breadth-first search coupled with pruning. The ?-CI and ?+SD-CI approaches are used to compute the dissociation curve of N{sub 2} and the potential energy curves for the first three singlet states of C{sub 2}. Special attention is paid to the issue of energy discontinuities caused by changes in the size of the ?-CI wave function along the potential energy curve. This problem is shown to be solvable by smoothing the matrix elements of the Hamiltonian. Our last example, involving the Cu{sub 2}O{sub 2}{sup 2+} core, illustrates an alternative use of the ?-CI method: as a tool to both estimate the multireference character of a wave function and to create a compact model space to be used in subsequent high-level multireference coupled cluster computations.

Evangelista, Francesco A., E-mail: francesco.evangelista@emory.edu [Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322 (United States)

2014-03-28

4

Violent Wave Motion due to Impact Violent Wave Motion due to Impact  

E-print Network

Violent Wave Motion due to Impact Violent Wave Motion due to Impact Mark J. Cooker School due to Impact Outline of Talk: Outline of Talk: 1. Sea Wave Impact Images: 2. Pressure-Impulse Theory 3. Example: Wave impact inside rectangular box 4. Results 5. Conclusions from Talk References: #12

5

Vortices in Atomic Wave Functions  

SciTech Connect

Vortices in atomic wave functions are shown to have observable consequences. It is shown that time-dependent electron wave functions in coordinate space go over to electron emission amplitudes in the limit that time becomes infinite. This relation between wave functions and emission amplitudes is called the imaging theorem. According to this theorem vortices in wave functions at small times when particles interact in a complex way appear as vortices in electron momentum distributions where they produce observable features. Conversely, some observable structures may be interpreted in terms of vortices no matter how they are seen or computed. We verify that previously unexplained features in (e,2e) triply differential cross sections can be interpreted in terms of vortices.

Macek, Joseph H [ORNL

2010-01-01

6

Wave-function functionals for the density  

SciTech Connect

We extend the idea of the constrained-search variational method for the construction of wave-function functionals {psi}[{chi}] of functions {chi}. The search is constrained to those functions {chi} such that {psi}[{chi}] reproduces the density {rho}(r) while simultaneously leading to an upper bound to the energy. The functionals are thereby normalized and automatically satisfy the electron-nucleus coalescence condition. The functionals {psi}[{chi}] are also constructed to satisfy the electron-electron coalescence condition. The method is applied to the ground state of the helium atom to construct functionals {psi}[{chi}] that reproduce the density as given by the Kinoshita correlated wave function. The expectation of single-particle operators W={Sigma}{sub i}r{sub i}{sup n}, n=-2,-1,1,2, W={Sigma}{sub i}{delta}(r{sub i}) are exact, as must be the case. The expectations of the kinetic energy operator W=-(1/2){Sigma}{sub i}{nabla}{sub i}{sup 2}, the two-particle operators W={Sigma}{sub n}u{sup n}, n=-2,-1,1,2, where u=|r{sub i}-r{sub j}|, and the energy are accurate. We note that the construction of such functionals {psi}[{chi}] is an application of the Levy-Lieb constrained-search definition of density functional theory. It is thereby possible to rigorously determine which functional {psi}[{chi}] is closer to the true wave function.

Slamet, Marlina; Pan Xiaoyin; Sahni, Viraht [Sacred Heart University, Fairfield, Connecticut 06825 (United States); Faculty of Science, Ningbo University, 315211 Ningbo (China); Brooklyn College and The Graduate School of the City University of New York, New York, New York 10016 (United States)

2011-11-15

7

The destructive impact of the rogue waves  

NASA Astrophysics Data System (ADS)

In our talk rogue waves at the ocean will be considered. By means of numerical modeling dangerous impact of rogue waves on the ships and oil rigs is calculated. Cases when these waves can bring in accident are considered. Using statistics of emergence of waves (see [1]-[2]), it is possible to estimate risks in each case. These results can be used for safety of the ships and oil rigs from rogue waves. References [1] V.E. Zakharov, A.I. Dyachenko, R.V. Shamin. How probability for freak wave formation can be found // THE EUROPEAN PHYSICAL JOURNAL - SPECIAL TOPICS Volume 185, Number 1, 113-124, DOI: 10.1140/epjst/e2010-01242-y [2] V.E. Zakharov, R.V. Shamin. Statistics of rogue waves in computer experiments // JETP Letters, 2012, V. 96, Issue 1, pp 66-69.

Shamin, Roman

2013-04-01

8

Meson wave function from holographic approaches  

SciTech Connect

We discuss the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence. We consider two kinds of wave functions obtained in different holographic Soft-Wall approaches.

Vega, Alfredo; Schmidt, Ivan [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Branz, Tanja; Gutsche, Thomas; Lyubovitskij, Valery E. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Kepler Center for Astro and Particle Physics, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2010-08-04

9

Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction  

NASA Astrophysics Data System (ADS)

Rapidly varying forces, such as those associated with impact, rapid crack propagation, and fault rupture, are sources of stress waves which propagate through a solid body. This dissertation investigates how properties of a stress wave source can be identified or constrained using measurements recorded at an array of sensor sites located far from the source. This methodology is often called the method of acoustic emission and is useful for structural health monitoring and the noninvasive study of material behavior such as friction and fracture. In this dissertation, laboratory measurements of 1--300 mm wavelength stress waves are obtained by means of piezoelectric sensors which detect high frequency (10 kHz--3MHz) motions of a specimen's surface, picometers to nanometers in amplitude. Then, stress wave source characterization techniques are used to study ball impact, drying shrinkage cracking in concrete, and the micromechanics of stick-slip friction of Poly(methyl methacrylate) (PMMA) and rock/rock interfaces. In order to quantitatively relate recorded signals obtained with an array of sensors to a particular stress wave source, wave propagation effects and sensor distortions must be accounted for. This is achieved by modeling the physics of wave propagation and transduction as linear transfer functions. Wave propagation effects are precisely modeled by an elastodynamic Green's function, sensor distortion is characterized by an instrument response function, and the stress wave source is represented with a force moment tensor. These transfer function models are verified though calibration experiments which employ two different mechanical calibration sources: ball impact and glass capillary fracture. The suitability of the ball impact source model, based on Hertzian contact theory, is experimentally validated for small (˜1 mm) balls impacting massive plates composed of four different materials: aluminum, steel, glass, and PMMA. Using this transfer function approach and the two mechanical calibration sources, four types of piezoelectric sensors were calibrated: three commercially available sensors and the Glaser-type conical piezoelectric sensor, which was developed in the Glaser laboratory. The distorting effects of each sensor are modeled using autoregressive-moving average (ARMA) models, and because vital phase information is robustly incorporated into these models, they are useful for simulating or removing sensor-induced distortions, so that a displacement time history can be retrieved from recorded signals. The Glaser-type sensor was found to be very well modeled as a unidirectional displacement sensor which detects stress wave disturbances down to about 1 picometer in amplitude. Finally, the merits of a fully calibrated experimental system are demonstrated in a study of stress wave sources arising from sliding friction, and the relationship between those sources and earthquakes. A laboratory friction apparatus was built for this work which allows the micro-mechanisms of friction to be studied with stress wave analysis. Using an array of 14 Glaser-type sensors, and precise models of wave propagation effects and the sensor distortions, the physical origins of the stress wave sources are explored. Force-time functions and focal mechanisms are determined for discrete events found amid the "noise" of friction. These localized events are interpreted to be the rupture of micrometer-sized contacts, known as asperities. By comparing stress wave sources from stick-slip experiments on plastic/plastic and rock/rock interfaces, systematic differences were found. The rock interface produces very rapid (<1 microsecond) implosive forces indicative of brittle asperity failure and fault gouge formation, while rupture on the plastic interface releases only shear force and produces a source more similar to earthquakes commonly recorded in the field. The difference between the mechanisms is attributed to the vast differences in the hardness and melting temperatures of the two materials, which affect the distribution of asp

McLaskey, Gregory Christofer

10

Impact of non-hydrostatic effects and trapped lee waves on mountain wave drag  

E-print Network

Impact of non-hydrostatic effects and trapped lee waves on mountain wave drag in directionally;AcceptedArticle Impact of non-hydrostatic effects and trapped lee waves on mountain wave drag gravity wave drag produced in flow over an axisymmetric mountain when both vertical wind shear and non

Wirosoetisno, Djoko

11

Impact damage detection in composite panels using guided ultrasonic waves  

NASA Astrophysics Data System (ADS)

Composite materials such as carbon fiber reinforced panels offer many advantages for aerospace applications, e.g, good strength to weight ratio. However, impact during the operation and servicing of the aircraft can lead to barely visible and difficult to detect damage. Depending on the severity of the impact, fiber breakage or delaminations can be induced which reduce the functionality of the structure. Efficient structural health monitoring of such plate-like components can be achieved using guided ultrasonic waves propagating along the structure and covering critical areas. However, the guided wave propagation in such anisotropic and inhomogeneous materials needs to be understood from theory and verified experimentally to achieve sufficient coverage of the structure. Using noncontact laser interferometer measurements the guided wave propagation in carbon fiber reinforced panels was investigated experimentally. Good agreement with calculations using a full three-dimensional Finite Element (FE) model was achieved. Impact damage was induced in the composite panels and the guided wave scattering at the damage measured and quantified. Good agreement with predictions was found and barely visible impact damage in composite panels detected.

Murat, Bibi Intan Suraya; Khalili, Pouyan; Fromme, Paul

2014-02-01

12

Meson wave function from holographic models  

SciTech Connect

We consider the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence, as has been suggested by Brodsky and Teramond. Two kinds of wave functions, obtained in different holographic Soft-Wall models, are discussed.

Vega, Alfredo; Schmidt, Ivan [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Branz, Tanja; Gutsche, Thomas; Lyubovitskij, Valery E. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Kepler Center for Astro and Particle Physics, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2009-09-01

13

Quantum Hall wave functions on the torus  

SciTech Connect

We present explicit expressions for a large set of hierarchy wave functions on the torus. Included are the Laughlin states, the states in the positive Jain series, and recently observed states at, e.g., {nu}=4/11. The techniques we use constitute a nontrivial extension of the conformal field theory methods developed earlier to construct the corresponding wave functions in disk geometry.

Hermanns, M.; Bergholtz, E. J.; Hansson, T. H.; Karlhede, A. [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Suorsa, J. [Laboratory of Physics, Helsinki University of Technology, FIN-02015 HUT (Finland)

2008-03-15

14

Hyperdeterminantal computation for the Laughlin wave function  

E-print Network

Hyperdeterminantal computation for the Laughlin wave function A. Boussicault, J.-G. Luque and C. Tollu October 6, 2008 Abstract The decomposition of the Laughlin wave function in the Slater orthogonal basis appears in the discussion on the second-quantized form of the Laughlin states

Paris-Sud XI, Université de

15

Spatial wave functions of photon and electron  

SciTech Connect

The quantum mechanical model of the photon and electron is considered. The photon is conceived of as a particle moving with the speed of light which is accompanied by the wave function of the photon spreading out with an infinite speed. The wave function of the electron is introduced in terms of virtual photons tied to the electron. A description of electrostatic and magnetostatic interactions is given through the wave functions of electrons. The approach provides an explanation of the results of recent experiments measuring the speed of propagation of the bound magnetic field.

Khokhlov, D. L. [Sumy State University, R.-Korsakov St. 2, Sumy 40007 (Ukraine)

2010-12-01

16

Monte Carlo comparison of quasielectron wave functions  

SciTech Connect

Variational Monte Carlo calculations of the quasielectron and quasihole excitation energies in the fractional quantum Hall effect have been carried out at filling fractions {nu}=1/3, 1/5, and 1/7. For the quasielectron both the trial wave function originally proposed by Laughlin and the composite-fermion wave function proposed by Jain have been used. We find that for long-range Coulomb interactions the results obtained using these two wave functions are essentially the same, though the energy gap obtained using the composite-fermion quasielectron is slightly smaller, and closer to extrapolated exact-diagonalization results. thinsp {copyright} {ital 1998} {ital The American Physical Society}

Melik-Alaverdian, V.; Bonesteel, N.E. [National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32306-4005 (United States)] [National High Magnetic Field Laboratory and Department of Physics, Florida State University, Tallahassee, Florida 32306-4005 (United States)

1998-07-01

17

The geometry of electron wave functions  

SciTech Connect

To each wave function we assign a codimension-two submanifold in Euclidean space. We study the case of the wave function of a single electron in the hydrogen atom or other hydrogen-type atoms with quantum numbers n, l, m in detail. We prove theorems describing the behaviour of the scalar and sectional curvature of the constructed submanifold, depending on the quantum numbers. We also consider the external geometry of the submanifold. Bibliography: 9 titles.

Aminov, Yurii A [B.Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, Khar'kov (Ukraine)] [B.Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, Khar'kov (Ukraine)

2013-02-28

18

Does wave function collapse cause gravity?  

E-print Network

We give a twist to the assumption - discussed in various earlier works - that gravity plays a role in the collapse of the wave function. This time we discuss the contrary assumption that the collapse of the wave function plays a role in the emergence of the gravitational field. We start from the mathematical framework of a particular Newtonian gravitational collapse theory proposed by the author longtime ago, and we reconciliate it with the classical equivalence principle.

Diósi, Lajos

2009-01-01

19

Interferometric Measurement of the Biphoton Wave Function  

NASA Astrophysics Data System (ADS)

Interference between an unknown two-photon state (a "biphoton") and the two-photon component of a reference state gives a phase-sensitive arrival-time distribution containing full information about the biphoton temporal wave function. Using a coherent state as a reference, we observe this interference and reconstruct the wave function of single-mode biphotons from a low-intensity narrow band squeezed vacuum state.

Beduini, Federica A.; Zieli?ska, Joanna A.; Lucivero, Vito G.; de Icaza Astiz, Yannick A.; Mitchell, Morgan W.

2014-10-01

20

The Maxwell wave function of the photon  

E-print Network

James Clerk Maxwell unknowingly discovered a correct relativistic, quantum theory for the light quantum, forty-three years before Einstein postulated the photon's existence. In this theory, the usual Maxwell field is the quantum wave function for a single photon. When the non-operator Maxwell field of a single photon is second quantized, the standard Dirac theory of quantum optics is obtained. Recently, quantum-state tomography has been applied to experimentally determine photon wave functions.

M. G. Raymer; Brian J. Smith

2006-04-24

21

Coulomb wave functions in momentum space  

NASA Astrophysics Data System (ADS)

An algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space is presented. The arguments are the Sommerfeld parameter ?, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p ? q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of | ? | in the range of 10-1 to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.

Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; Elster, Ch.; Nunes, F. M.; Arbanas, G.; Escher, J. E.; Hlophe, L.

2015-02-01

22

The Wave Function and Quantum Reality  

SciTech Connect

We investigate the meaning of the wave function by analyzing the mass and charge density distributions of a quantum system. According to protective measurement, a charged quantum system has effective mass and charge density distributing in space, proportional to the square of the absolute value of its wave function. In a realistic interpretation, the wave function of a quantum system can be taken as a description of either a physical field or the ergodic motion of a particle. The essential difference between a field and the ergodic motion of a particle lies in the property of simultaneity; a field exists throughout space simultaneously, whereas the ergodic motion of a particle exists throughout space in a time-divided way. If the wave function is a physical field, then the mass and charge density will be distributed in space simultaneously for a charged quantum system, and thus there will exist gravitational and electrostatic self-interactions of its wave function. This not only violates the superposition principle of quantum mechanics but also contradicts experimental observations. Thus the wave function cannot be a description of a physical field but be a description of the ergodic motion of a particle. For the later there is only a localized particle with mass and charge at every instant, and thus there will not exist any self-interaction for the wave function. It is further argued that the classical ergodic models, which assume continuous motion of particles, cannot be consistent with quantum mechanics. Based on the negative result, we suggest that the wave function is a description of the quantum motion of particles, which is random and discontinuous in nature. On this interpretation, the square of the absolute value of the wave function not only gives the probability of the particle being found in certain locations, but also gives the probability of the particle being there. The suggested new interpretation of the wave function provides a natural realistic alternative to the orthodox interpretation, and it also implies that the de Broglie-Bohm theory and many-worlds interpretation are wrong and the dynamical collapse theories are in the right direction by admitting wavefunction collapse.

Gao Shan [Unit for History and Philosophy of Science and Centre for Time, SOPHI, University of Sydney, Sydney, NSW 2006 (Australia)

2011-03-28

23

The Wave Function and Quantum Reality  

NASA Astrophysics Data System (ADS)

We investigate the meaning of the wave function by analyzing the mass and charge density distributions of a quantum system. According to protective measurement, a charged quantum system has effective mass and charge density distributing in space, proportional to the square of the absolute value of its wave function. In a realistic interpretation, the wave function of a quantum system can be taken as a description of either a physical field or the ergodic motion of a particle. The essential difference between a field and the ergodic motion of a particle lies in the property of simultaneity; a field exists throughout space simultaneously, whereas the ergodic motion of a particle exists throughout space in a time-divided way. If the wave function is a physical field, then the mass and charge density will be distributed in space simultaneously for a charged quantum system, and thus there will exist gravitational and electrostatic self-interactions of its wave function. This not only violates the superposition principle of quantum mechanics but also contradicts experimental observations. Thus the wave function cannot be a description of a physical field but be a description of the ergodic motion of a particle. For the later there is only a localized particle with mass and charge at every instant, and thus there will not exist any self-interaction for the wave function. It is further argued that the classical ergodic models, which assume continuous motion of particles, cannot be consistent with quantum mechanics. Based on the negative result, we suggest that the wave function is a description of the quantum motion of particles, which is random and discontinuous in nature. On this interpretation, the square of the absolute value of the wave function not only gives the probability of the particle being found in certain locations, but also gives the probability of the particle being there. The suggested new interpretation of the wave function provides a natural realistic alternative to the orthodox interpretation, and it also implies that the de Broglie-Bohm theory and many-worlds interpretation are wrong and the dynamical collapse theories are in the right direction by admitting wavefunction collapse.

Gao, Shan

2011-03-01

24

Coulomb Wave Functions in Repulsive Fields  

Microsoft Academic Search

Quantitative discussion of nuclear reactions due to bombardment with charged particles requires the knowledge of wave functions in repulsive inverse square fields of force. It is customary to approximate these functions by formulas of the type due to Wentzel, Kramers and Brillouin (referred to as WKB). Errors of unknown amount are frequently introduced by such approximations. Formulas necessary for the

F. L. Yost; John A. Wheeler; G. Breit

1936-01-01

25

Variational Wave Functions for Frustrated Magnetic Models  

Microsoft Academic Search

\\u000a Variational wave functions containing electronic pairing and suppressed charge fluctuations (i.e., projected BCS states) have\\u000a been proposed as the paradigm for disordered magnetic systems (including spin liquids). Here, we discuss the general properties\\u000a of these states in one and two dimensions, and show that different quantum phases may be described with high accuracy by the\\u000a same class of variational wave

Federico Becca; Luca Capriotti; Alberto Parola; Sandro Sorella

2009-01-01

26

Swell-Dissipation Function for Wave Models  

NASA Astrophysics Data System (ADS)

In the paper, we will investigate swell attenuation due to production of turbulence by the wave orbital motion. Theoreticaly, potential waves cannot generate the vortex motion, but the scale considerations indicate that if the steepness of waves is not too small, the Reynolds number can exceed the critical values. This means that in presence of initial non-potential disturbances the orbital velocities can generate the vortex motion and turbulence. This problem was investigated by laboratory means, numerical simulations and field observations. As a sink of wave energy, such dissipation is small in presence of wave breaking, but is essential for swell. Swell prediction by spectral wave models is often poor, but is important for offshore and maritime industry, and across a broad range of oceanographic and air-sea interaction applications. Based on the research of wave-induced turbulence, new swell-dissipation function is proposed. It agrees well with satellite observations of long-distance swell propagation and has been employed and tested in spectral wave models.

Babanin, A.

2012-04-01

27

Breaking wave impact pressures on a vertical wall  

NASA Astrophysics Data System (ADS)

The growing concern for the proper utilization of the coastal zone resulted in increased efforts by researchers in understanding the coastal zone dynamics. The wall type structures are widely adopted by coastal engineers for the purpose of breakwaters and coastal protection works. These structures are designed to withstand the environmental loads due to waves, tides and currents. The interaction of these loads and their variability makes design of these structures more complex. These vertical walls are at times subjected to severe wave loads, the worst being those caused by breaking wave impact. Impact forces can be two to four times larger than the non-impact forces even though the incident wave amplitudes are comparable. Also, within the region of wave impact, pressures can be ten to fifteen times larger than the non impact pressures. Such impulse wave loads can easily lead to local fatigue problems and even local damage. It is clear that a good understanding of wave impact on structures is also important for offshore engineers. In the present study, the imparted pressures resulting from a single plunging wave impact on a vertical wall is studied through laboratory experiments. The experiments were conducted in the 30m long current cum wave flume of the Department of Ocean Engineering, I.I.T-Madras. The flume is 2m wide and 1.0m deep. A water depth of 0.8m was adopted for the experiments. The vertical wall, of size 2m wide and 1.2m high, was fabricated using a fiber board of 10mm thickness and supported by a mild steel angle frame. Wave plunging was simulated through the frequency modulated wave packet. The non-dimensionalized peak impact pressure, P/Cc2 has been measured in the range of 0.104 to 0.316 for various relative position of vertical wall with respect to the point of wave breaking in a narrower range, x/xb of 0.982 to 1.025, where xb is the point of wave breaking where the wave attains maximum steepness. The duration of wave impact , t / Tc ranges from 17.45 to 17.73. The maximum impact pressure was observed to occur above the still water level, z/d at 0.12 to 0.18. The duration during which the maximum impulse pressure occurred was estimated to be less than 0.01Tc .The breaking wave impact pressures were found to be 10 to 15 times more than the non-breaking wave dynamic pressures.

Sannasi A., S.; Naik, M. S.

2009-04-01

28

Multifractal wave functions of simple quantum maps.  

PubMed

We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like transition recently implemented with cold atoms. Using extensive numerical simulations, we compute the multifractal exponents of quantum wave functions and study their properties, with the help of two different numerical methods used for classical multifractal systems (box-counting and wavelet methods). We compare the results of the two methods over a wide range of values. We show that the wave functions of the Anderson map display a multifractal behavior similar to eigenfunctions of the three-dimensional Anderson transition but of a weaker type. Wave functions of the intermediate map share some common properties with eigenfunctions at the Anderson transition (two sets of multifractal exponents, with similar asymptotic behavior), but other properties are markedly different (large linear regime for multifractal exponents even for strong multifractality, different distributions of moments of wave functions, and absence of symmetry of the exponents). Our results thus indicate that the intermediate map presents original properties, different from certain characteristics of the Anderson transition derived from the nonlinear sigma model. We also discuss the importance of finite-size effects. PMID:21230364

Martin, John; García-Mata, Ignacio; Giraud, Olivier; Georgeot, Bertrand

2010-10-01

29

Designing electron wave functions in assembled nanostructures  

NASA Astrophysics Data System (ADS)

We use the scanning tunneling microscope to not only to map electron wave functions but also to engineer them. By assembling nanostructures from individual atoms and molecules, we confine two-dimensional electronic states into closed electron resonators, or "quantum corrals". Precise control over the geometry of these structures allows electronic states to be tailored to suit particular experiments. Specifically, we design wave functions that enable studies of normally inaccessible quantum phases. First, we create pairs of quantum corrals with shapes drawn from contemporary mathematics. Exploiting special topological relationships between these structures, we retrieve internal quantum phase of electron wave functions without using interferometry. Second, we demonstrate that adding a single atom to a quantum corral can cause its electronic states to recombine into coherent superpositions. The real-space position of the additional atom controls abstract superposition phase angles, enabling arbitrary time-independent superpositions to be created. Third, we study geometric phase by creating a series of quantum corrals that traverse a closed path through a parameter space. Tracking the corral wave functions reveals a phase shift depending solely on the path taken, directly visualizing Berry's phase evolution in a quantum system. Finally, we extend beyond closed electron resonators and engineer wave functions in open nanostructures. We show that arbitrary patterns can be encoded into electronic states, creating a new form of holography on the nanoscale. We exhibit letters written in electron density rather than with atomic matter, and show that multiple letters may be simultaneously embedded at different energies in the same region of space. Because the wavelength of the electrons diminishes as energy is increased, this technique allows local information densities that exceed the conventionally assumed limit of 1 bit per atom. Taken together, the results in this thesis demonstrate unprecedented control of electron states in condensed matter and illuminate fundamental quantum phases that underlie systems ranging from coherent electronic devices to complex quantum materials.

Moon, Christopher Ryan

30

Wave Function Microscopy of Quasibound Atomic States  

NASA Astrophysics Data System (ADS)

In the 1980s Demkov, Kondratovich, and Ostrovsky and Kondratovich and Ostrovsky proposed an experiment based on the projection of slow electrons emitted by a photoionized atom onto a position-sensitive detector. In the case of resonant excitation, they predicted that the spatial electron distribution on the detector should represent nothing else but a magnified image of the projection of a quasibound electronic state. By exciting lithium atoms in the presence of a static electric field, we present in this Letter the first experimental photoionization wave function microscopy images where signatures of quasibound states are evident. Characteristic resonant features, such as (i) the abrupt change of the number of wave function nodes across a resonance and (ii) the broadening of the outer ring of the image (associated with tunneling ionization), are observed and interpreted via wave packet propagation simulations and recently proposed resonance tunneling mechanisms. The electron spatial distribution measured by our microscope is a direct macroscopic image of the projection of the microscopic squared modulus of the electron wave that is quasibound to the atom and constitutes the first experimental realization of the experiment proposed 30 years ago.

Cohen, S.; Harb, M. M.; Ollagnier, A.; Robicheaux, F.; Vrakking, M. J. J.; Barillot, T.; Lépine, F.; Bordas, C.

2013-05-01

31

Wave function microscopy of quasibound atomic states.  

PubMed

In the 1980s Demkov, Kondratovich, and Ostrovsky and Kondratovich and Ostrovsky proposed an experiment based on the projection of slow electrons emitted by a photoionized atom onto a position-sensitive detector. In the case of resonant excitation, they predicted that the spatial electron distribution on the detector should represent nothing else but a magnified image of the projection of a quasibound electronic state. By exciting lithium atoms in the presence of a static electric field, we present in this Letter the first experimental photoionization wave function microscopy images where signatures of quasibound states are evident. Characteristic resonant features, such as (i) the abrupt change of the number of wave function nodes across a resonance and (ii) the broadening of the outer ring of the image (associated with tunneling ionization), are observed and interpreted via wave packet propagation simulations and recently proposed resonance tunneling mechanisms. The electron spatial distribution measured by our microscope is a direct macroscopic image of the projection of the microscopic squared modulus of the electron wave that is quasibound to the atom and constitutes the first experimental realization of the experiment proposed 30 years ago. PMID:23683194

Cohen, S; Harb, M M; Ollagnier, A; Robicheaux, F; Vrakking, M J J; Barillot, T; Lépine, F; Bordas, C

2013-05-01

32

Universal wave functions structure in mixed systems  

E-print Network

When a regular classical system is perturbed, non-linear resonances appear as prescribed by the KAM and Poincar\\`{e}-Birkhoff theorems. Manifestations of this classical phenomena to the morphologies of quantum wave functions are studied in this letter. We reveal a systematic formation of an universal structure of localized wave functions in systems with mixed classical dynamics. Unperturbed states that live around invariant tori are mixed when they collide in an avoided crossing if their quantum numbers differ in a multiple to the order of the classical resonance. At the avoided crossing eigenstates are localized in the island chain or in the vicinity of the unstable periodic orbit corresponding to the resonance. The difference of the quantum numbers determines the excitation of the localized states which is reveled using the zeros of the Husimi distribution.

Diego A. Wisniacki

2014-03-02

33

Modeling of Wave Impact Using a Pendulum System  

E-print Network

body swinging on a pendulum system is developed. The body on the pendulum goes through a wave free surface driven by gravity at the pendulum's natural frequency. The system's motion and impact force during the entire oscillation time beginning from...

Nie, Chunyong

2011-08-08

34

Wave Function Based Characteristics of Hybrid Mesons  

E-print Network

We propose some extensions of the quark potential model to hybrids, fit them to the lattice data and use them for the purpose of calculating the masses, root mean square radii and wave functions at the origin of the conventional and hybrid charmonium mesons. We treat the ground and excited gluonic field between a quark and an antiquark as in the Born-Oppenheimer expansion, and use the shooting method to numerically solve the required Schr$\\ddot{\\textrm{o}}$dinger equation for the radial wave functions; from these wave functions we calculate the mesonic properties. For masses we also check through a Crank Nichelson discretization. For hybrid charmonium mesons, we consider the exotic quantum number states with $ J^{PC} = 0^{+ -}, 1^{- +}$ and $2^{+ -}$. We also compare our results with the experimentally observed masses and theoretically predicted results of the other models. Our results have implications for scalar form factors, energy shifts, magnetic polarizabilities, decay constants, decay widths and differential cross sections of conventional and hybrid mesons.

Nosheen Akbar; Bilal Masud; Saba Noor

2014-04-07

35

Wave function methods for fractional electrons  

NASA Astrophysics Data System (ADS)

Determining accurate chemical potentials is of considerable interest in various chemical and physical contexts: from small molecular charge-transfer complexes to bandgap in bulk materials such as semi-conductors. Chemical potentials are typically evaluated either by density functional theory, or, alternatively, by computationally more intensive Greens function based GW computations. To calculate chemical potentials, the ground state energy needs to be defined for fractional charges. We thus explore an extension of wave function theories to fractional charges, and investigate the ionization potential and electron affinity as the derivatives of the energy with respect to the electron number. The ultimate aim is to access the chemical potential of correlated wave function methods without the need of explicitly changing the numbers of electrons, making the approach readily applicable to bulk materials. We find that even though second order perturbation theory reduces the fractional charge error considerably compared to Hartree-Fock and standard density functionals, higher order perturbation theory is more accurate and coupled-cluster approaches are even more robust, provided the electrons are bound at the Hartree-Fock level. The success of post-HF approaches to improve over HF relies on two equally important aspects: the integer values are more accurate and the Coulomb correlation between the fractionally occupied orbital and all others improves the straight line behavior significantly as identified by a correction to Hartree-Fock. Our description of fractional electrons is also applicable to fractional spins, illustrating the ability of coupled-cluster singles and doubles to deal with two degenerate fractionally occupied orbitals, but its inadequacy for three and more fractional spins, which occur, for instance, for spherical atoms and when dissociating double bonds. Our approach explores the realm of typical wave function methods that are applied mostly in molecular chemistry, but become available to the solid state community and offer the advantage of an integrated approach: fundamental gap, relative energies, and optimal geometries can be obtained at the same level.

Steinmann, Stephan N.; Yang, Weitao

2013-08-01

36

Love wave propagation in functionally graded piezoelectric material layer  

E-print Network

Love wave propagation in functionally graded piezoelectric material layer Jianke Du *, Xiaoying Jin is used to investigate Love waves in functionally graded piezoelectric material (FGPM) layer bonded. Numerical examples indicate that appropriate gradient distributing of the material properties make Love

Wang, Ji

37

Impact of Functionally Graded Cylinders: Theory  

NASA Technical Reports Server (NTRS)

This final report summarizes the work funded under the Grant NAG3-2411 during the 04/05/2000-04/04/2001 period. The objective of this one-year project was to generalize the theoretical framework of the two-dimensional higher-order theory for the analysis of cylindrical functionally graded materials/structural components employed in advanced aircraft engines developed under past NASA Glenn funding. The completed generalization significantly broadens the theory's range of applicability through the incorporation of dynamic impact loading capability into its framework. Thus, it makes possible the assessment of the effect of damage due to fuel impurities, or the presence of submicron-level debris, on the life of functionally graded structural components. Applications involving advanced turbine blades and structural components for the reusable-launch vehicle (RLV) currently under development will benefit from the completed work. The theory's predictive capability is demonstrated through a numerical simulation of a one-dimensional wave propagation set up by an impulse load in a layered half-plane. Full benefit of the completed generalization of the higher-order theory described in this report will be realized upon the development of a related computer code.

Aboudi, Jacob; Pindera, Marek-Jerzy; Arnold, S. M. (Technical Monitor)

2001-01-01

38

Extreme waves impact on the ship mooring near berth  

NASA Astrophysics Data System (ADS)

Ensuring safe ships berthing and loading-unloading operations at berths need reliable mooring systems. The choice of its parameters corresponds to calculating of the maximum displacements of the boat, which are caused by external impact of extreme waves, winds, and currents. Ship motions are described by system of differential equations, which contain disturbing, inertia, damping, and restoring forces, which magnitude strongly depends on the berth design and configuration of its elements. The major impact on the boat movements is caused by sea waves. In the given paper, an interaction between sea waves and ship located near the berth is studied. The cross-sectional shape of the boat is assumed to be rectangular and under-berth slope profile is approximated by finite number of steps. Different types of berth constructions are taken into account: containing impermeable or partially permeable front vertical wall, wave attenuation camera behind it with or without under-berth slope. The fluid is assumed ideal and incompressible, and its motion is potential. The stated problem is reduced to the determination of the velocity potential that satisfies the Laplace equation; the boundary condition on the free surface; the condition of non-flux through the impermeable bottom, the ship and berth elements; the condition on the surface of the permeable wall that is in proportionality between the wave flow velocity through the wall and pressure drop from its front to back faces. The problem is solved by dividing of the region into sub-domains with conditions of the hydrodynamic pressure and velocity continuity on its boundaries. In each sub-domain the solution is found using Fourier method in the form of functional series with unknown coefficients which are found from the system of linear algebraic equations. Calculated velocity potentials are used to determine different hydrodynamic characteristics of ship motions, such as horizontal and vertical components of disturbing force and moment, added masses and damping coefficients for all types of boat motions. The results of calculations are presented and they are compared with experimental data performed by authors.

Leont'ev, Victor; Nudner, Igor; Semenov, Konstantin; Pelinovsky, Efim

2013-04-01

39

On Dissipation Function of Ocean Waves due to Whitecapping.  

E-print Network

On Dissipation Function of Ocean Waves due to Whitecapping. V.E. Zakharov, A.O. Korotkevich, and A Dissipation Function of Ocean Waves due to White Capping. Scheme of scales kp1 k=2/ pumping inverse cascade Function of Ocean Waves due to White Capping. Why it is important? ­ L.D. Landau ITP RAS ­ Zakharov-70, SCT

Fominov, Yakov

40

Parametric Dependence of Ocean Wave-Radar Modulation Transfer Functions  

Microsoft Academic Search

much smaller when the antennas are pointed perpendicular to long waves, however. X band transfer functions measured with horizontally polarized microwave radiation are found to have larger magnitudes than those obtained by using vertical polarization. Under conditions encountered in this experiment, transfer functions are independent of long-wave amplitude when waves and antennas are aligned. Coherence functions, however, depend strongly on

W. J. Plant; W. C. Keller; A. Cross

1983-01-01

41

Impact of simulated heat waves on soybean physiology and yield  

Technology Transfer Automated Retrieval System (TEKTRAN)

With increases in mean global temperatures and associated climate change, extreme temperature events are predicted to increase in both intensity and frequency. Despite the clearly documented negative public health impacts of heat waves, the impact on physiology and yields of key agricultural species...

42

Comparison of wave structure functions for intensity profiles  

NASA Astrophysics Data System (ADS)

We give a list of available wave structure functions (WSFs) of a spherical wave, simultaneously providing some derivation details. The aim is to assess the impact of these WSFs on intensity profiles of various beams propagating in turbulence. For comparisons, coherent and partially coherent fundamental Gaussian, hyperbolic, sinusoidal and annular Gaussian beams are chosen. Comparisons are made by calculating the difference between the intensity profiles of the analytic solution that uses the normalized WSF with quadratic approximation and the intensity profiles obtained by numerically solving the quadruple extended Huygens-Fresnel integral containing other WSFs. The graphical results show that in general the differences arising from the use of different WSFs are not substantial. Such differences become much greater however toward the complete incoherence limit and at relatively higher structure constant values. Even then, at these extremes, the receiver intensity levels are much reduced, making such big differences immaterial.

Eyyubo?lu, H. T.

2009-03-01

43

Guided ultrasonic waves for impact damage detection in composite panels  

NASA Astrophysics Data System (ADS)

Carbon fiber laminate composites, consisting of layers of polymer matrix reinforced with high strength carbon fibers, are increasingly employed for aerospace structures. They offer advantages for aerospace applications, e.g., good strength to weight ratio. However, impact during the operation and servicing of the aircraft can lead to barely visible and difficult to detect damage. Depending on the severity of the impact, fiber and matrix breakage or delaminations can occur, reducing the load carrying capacity of the structure. Efficient structural health monitoring of composite panels can be achieved using guided ultrasonic waves propagating along the structure. Impact damage was induced in the composite panels using standard drop weight procedures. The guided wave scattering at the impact damage was measured using a noncontact laser interferometer, quantified, and compared to baseline measurements on undamaged composite panels. Significant scattering of the first anti-symmetrical (A0) guided wave mode was observed, allowing for the detection of barely visible impact damage. The guided wave scattering was modeled using full three-dimensional Finite Element (FE) simulations, and the influence of the different damage mechanisms investigated. Good agreement between experiments and predictions was found. The sensitivity of guided waves for the detection of barely visible impact damage in composite panels has been verified.

Murat, B. I. S.; Khalili, P.; Fromme, P.

2014-03-01

44

PRESSURE IMPULSES CAUSED BY WAVE IMPACT  

E-print Network

, a surface-piercing body experiences a vertical impulse when a wave breaks against a nearby vertical wall cold gray stones, O Sea! And I would that my tongue could utter The thoughts that arise in me. Alfred

Cox, Simon

45

The resonance wave function - is it relevant?  

SciTech Connect

The physical relevance of the resonance wave function is discussed in view of the complex scaling theory. It is argued that although it is unphysical in the sense that it corresponds to a complex energy it is useful when we want to understand and compute several physical observables. We first review our work on the influence of resonances on a scattering cross sections. We then discuss the partial widths concept as presented by Peshkin, Moiseyev and Lefebvre [J. Chem. Phys. 92 2902 (1990)]. Finally we use this formalism to suggest a way to define a root mean square radius of a resonant state.

Elander, Nils; Shilyeava, Ksenia; Volkov, Mikhail [Stockholm University, Alba Nova University Center, Division of Molecular Physics, SE 106 91 Stockholm (Sweden); Yarevsky, Evgeny [Department of Mathematical and Computational Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Rakityansky, Sergei [Dept. of Physics, University of South Africa, P.O. Box 392, Pretoria (South Africa)

2008-04-03

46

Wave functions of log-periodic oscillators  

SciTech Connect

We use the Lewis and Riesenfeld invariant method [J. Math. Phys. 10, 1458 (1969)] and a unitary transformation to obtain the exact Schroedinger wave functions for time-dependent harmonic oscillators exhibiting log-periodic-type behavior. For each oscillator we calculate the quantum fluctuations in the coordinate and momentum as well as the quantum correlations between the coordinate and momentum. We observe that the oscillator with m=m{sub 0}t/t{sub 0} and {omega}={omega}{sub 0}t{sub 0}/t, which exhibits an exact log-periodic oscillation, behaves as the harmonic oscillator with m and {omega} constant.

Bessa, V.; Guedes, I. [Departamento de Fisica, Universidade Federal do Ceara, Campus do Pici, Fortaleza, CE 60455-760 (Brazil)

2011-06-15

47

Analysis of the impacts of Wave Energy Converter arrays on the nearshore wave climate in the Pacific Northwest  

NASA Astrophysics Data System (ADS)

As concerns over the use of fossil fuels increase, more and more effort is being put into the search for renewable and reliable sources of energy. Developments in ocean technologies have made the extraction of wave energy a promising alternative. Commercial exploitation of wave energy would require the deployment of arrays of Wave Energy Converters (WECs) that include several to hundreds of individual devices. Interactions between WECs and ocean waves result in both near-field and far-field changes in the incident wave field, including a significant decrease in wave height and a redirection of waves in the lee of the array, referred to as the wave shadow. Nearshore wave height and direction are directly related to the wave radiation stresses that drive longshore currents, rip currents and nearshore sediment transport, which suggests that significant far-field changes in the wave field due to WEC arrays could have an impact on littoral processes. The goal of this study is to investigate the changes in nearshore wave conditions and radiation stress forcing as a result of an offshore array of point-absorber type WECs using a nested SWAN model, and to determine how array size, configuration, spacing and distance from shore influence these changes. The two sites of interest are the Northwest National Marine Renewable Energy Center (NNMREC) test sites off the coast of Newport Oregon, the North Energy Test Site (NETS) and the South Energy Test Site (SETS). NETS and SETS are permitted wave energy test sites located approximately 4 km and 10 km offshore, respectively. Twenty array configurations are simulated, including 5, 10, 25, 50 and 100 devices in two and three staggered rows in both closely spaced (three times the WEC diameter) and widely spaced (ten times the WEC diameter) arrays. Daily offshore wave spectra are obtained from a regional WAVEWATCH III hindcast for 2011, which are then propagated across the continental shelf using SWAN. Arrays are represented in SWAN through the external modification of the wave spectra at the device locations, based on a new experimentally determined Power Transfer Function established in an earlier WEC-array laboratory study. Changes in nearshore forcing conditions for each array size and configuration are compared in order to determine the scale of the far-field effects of WEC arrays and which array sizes and configurations could have the most significant impacts on coastal processes.

O'Dea, A.; Haller, M. C.

2013-12-01

48

Green's Functions of Wave Equations in {R}^n_+× {R}_+  

NASA Astrophysics Data System (ADS)

We study the d'Alembert equation with a boundary. We introduce the notions of Rayleigh surface wave operators, delayed/advanced mirror images, wave recombinations, and wave cancellations. This allows us to obtain the complete and simple formula of the Green's functions for the wave equation with the presence of various boundary conditions. We are able to determine whether a Rayleigh surface wave is active or virtual, and study the lacunas of the wave equation in three dimensional with the presence of a boundary in the case of a virtual Rayleigh surface wave.

Deng, Shijin; Wang, Weike; Yu, Shih-Hsien

2014-12-01

49

String wave function across a Kasner singularity  

SciTech Connect

A collision of orbifold planes in 11 dimensions has been proposed as an explanation of the hot big bang. When the two planes are close to each other, the winding membranes become the lightest modes of the theory, and can be effectively described in terms of fundamental strings in a ten-dimensional background. Near the brane collision, the 11-dimensional metric is a Euclidean space times a 1+1-dimensional Milne universe. However, one may expect small perturbations to lead into a more general Kasner background. In this paper we extend the previous classical analysis of winding membranes to Kasner backgrounds, and using the Hamiltonian equations, solve for the wave function of loops with circular symmetry. The evolution across the singularity is regular, and explained in terms of the excitement of higher oscillation modes. We also show there is finite particle production and unitarity is preserved.

Copeland, Edmund J.; Niz, Gustavo [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Turok, Neil [Perimeter Institute for Theoretical Physics, 31 Caroline Street N, Waterloo, Ontario N2L2Y5 (Canada)

2010-06-15

50

Hyperdeterminantal computation for the Laughlin wave function  

E-print Network

The decomposition of the Laughlin wave function in the Slater orthogonal basis appears in the discussion on the second-quantized form of the Laughlin states and is straightforwardly equivalent to the decomposition of the even powers of the Vandermonde determinants in the Schur basis. Such a computation is notoriously difficult and the coefficients of the expansion have not yet been interpreted. In our paper, we give an expression of these coefficients in terms of hyperdeterminants of sparse tensors. We use this result to construct an algorithm allowing to compute one coefficient of the development without computing the others. Thanks to a program in {\\tt C}, we performed the calculation for the square of the Vandermonde up to an alphabet of eleven lettres.

Adrien Boussicault; Jean-Gabriel Luque; Christophe Tollu

2008-10-06

51

Pain's Impact on Adaptive Functioning  

ERIC Educational Resources Information Center

Background: Pain interferes with the functioning of typical children, but no study has examined its effect on children with pre-existing intellectual disabilities (ID). Methods: Caregivers of 63 children observed their children for 2-h periods and recorded in 1-week diaries: pain presence, cause, intensity and duration. Caregivers also recorded…

Breau, L. M.; Camfield, C. S.; McGrath, P. J.; Finley, G. A.

2007-01-01

52

Semiclassical approach to K shell ionization: hydrogenic wave functions  

Microsoft Academic Search

Proton induced K shell ionization cross sections in several elements were calculated. Semiclassical approximation with momentum space approach, hydrogenic wave functions and outer screening according to the prescription of Bethe was used. Comparison with other semiclassical and Dirac-Hartree-Slater [DHS] plane wave cross sections indicates that this type of screening — largely used in plane wave methods — implies a less

Ž. Šmit

1991-01-01

53

Iteration wave function for describing the (e, 2e) spectrum of the helium atom  

NASA Astrophysics Data System (ADS)

The wave function of the ground state of the helium atom is derived by the variational-iteration technique with the Hylleraas-Eckart momentum representation of the wave function as a first approximation. This function is used to calculate the ratios of the differential cross sections ?(n=2)/?(n=1) and ?(2p)/?(2s) for helium ionized by an electron impact. The calculation is conducted in the plane-wave impulse approximation for symmetric noncoplanar kinematics of the (e, 2e) process. The results are compared with previous calculations in which variational wave functions of the configurational interaction type were used. Good agreement with the existing experimental data for ?(n=2)/?(n=1) is obtained. The results are generalized to helium ions.

Ippolitov, I. I.; Katyurin, S. V.; Glinkin, O. B.

1986-12-01

54

Six Impossible Things: Fractional Charge From Laughlin's Wave Function  

SciTech Connect

The Laughlin's wave function is found to be the zero-energy ground state of a {delta}-function Hamiltonian. The finite negative value of the ground state energy which is 91 per cent of Wigner value, can be obtained only when Coulomb correlations are introduced. The Laughlin's wave function is of short range and it overlaps with that of the exact wave functions of small (number of electrons 2 or 5) systems. (i) It is impossible to obtain fractional charge from Laughlin's wave function. (ii) It is impossible to prove that the Laughlin's wave function gives the ground state of the Coulomb Hamiltonian. (iii) It is impossible to have particle-hole symmetry in the Laughlin's wave function. (iv) It is impossible to derive the value of m in the Laughlin's wave function. The value of m in {psi}{sub m} can not be proved to be 3 or 5. (v) It is impossible to prove that the Laughlin's state is incompressible because the compressible states are also likely. (vi) It is impossible for the Laughlin's wave function to have spin. This effort is directed to explain the experimental data of quantum Hall effect in GaAs/AlGaAs.

Shrivastava, Keshav N. [Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia)

2010-12-23

55

Photon wave functions, wave-packet quantization of light, and coherence theory  

E-print Network

The monochromatic Dirac and polychromatic Titulaer-Glauber quantized field theories (QFTs) of electromagnetism are derived from a photon-energy wave function in much the same way that one derives QFT for electrons, that is, by quantization of a single-particle wave function. The photon wave function and its equation of motion are established from the Einstein energy-momentum-mass relation, assuming a local energy density. This yields a theory of photon wave mechanics (PWM). The proper Lorentz-invariant single-photon scalar product is found to be non-local in coordinate space, and is shown to correspond to orthogonalization of the Titulaer-Glauber wave-packet modes. The wave functions of PWM and mode functions of QFT are shown to be equivalent, evolving via identical equations of motion, and completely describe photonic states. We generalize PWM to two or more photons, and show how to switch between the PWM and QFT viewpoints. The second-order coherence tensors of classical coherence theory and the two-photon wave functions are shown to propagate equivalently. We give examples of beam-like states, which can be used as photon wave functions in PWM, or modes in QFT. We propose a practical mode converter based on spectral filtering to convert between wave packets and their corresponding biorthogonal dual wave packets.

Brian J. Smith; M. G. Raymer

2007-08-06

56

Nodal structure and global behavior of scattering wave functions  

SciTech Connect

The global wave function is obtained for finite element calculations of H+H/sub 2/. The wave function is a linear combination of linear solutions which are symmetric and antisymmetric to a reflection plane on the potential surface. Boundary conditions are discussed. (AIP)

Askar, A.; Cakmak, A.S.; Rabitz, H.

1980-05-01

57

Influence of Superpositional Wave Function Oscillations on Shor's Quantum Algorithm  

Microsoft Academic Search

We investigate the influence of superpositional wave function oscillations on the performance of Shor's quantum algorithm for factorization of integers. It is shown that wave function oscillations can modify the required quantum interference. This undesirable effect can be routinely eliminated using a resonant pulse implementation of quantum computation, but requires special analysis for nonresonant implementations. We also discuss the influence

Gennady P. Berman; Gary D. Doolen; Vladimir I. Tsifrinovich

2000-01-01

58

Imaging the wave functions of adsorbed molecules  

PubMed Central

The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust. PMID:24344291

Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter

2014-01-01

59

Chameleonic equivalence postulate and wave function collapse  

E-print Network

A chameleonic solution to the cosmological constant problem and the non-equivalence of different conformal frames at the quantum level have been recently suggested [Phys. Rev. D82 (2010) 044006]. In this article we further discuss the theoretical grounds of that model and we are led to a chameleonic equivalence postulate (CEP). Whenever a theory satisfies our CEP (and some other additional conditions), a density-dependence of the mass of matter fields is naturally present. Let us summarize the main results of this paper. 1) The CEP can be considered the microscopic counterpart of the Einstein's Equivalence Principle and, hence, a chameleonic description of quantum gravity is obtained: in our model, (quantum) gravitation is equivalent to a conformal anomaly. 2) To illustrate one of the possible applications of the CEP, we point out a connection between chameleon fields and quantum-mechanical wave function collapse. The collapse is induced by the chameleonic nature of the theory. We discuss the collapse for a Stern-Gerlach experiment and for a diffraction experiment with electrons. More research efforts are necessary to verify whether these ideas are compatible with phenomenological constraints.

Andrea Zanzi

2014-04-03

60

Imaging the wave functions of adsorbed molecules.  

PubMed

The basis for a quantum-mechanical description of matter is electron wave functions. For atoms and molecules, their spatial distributions and phases are known as orbitals. Although orbitals are very powerful concepts, experimentally only the electron densities and -energy levels are directly observable. Regardless whether orbitals are observed in real space with scanning probe experiments, or in reciprocal space by photoemission, the phase information of the orbital is lost. Here, we show that the experimental momentum maps of angle-resolved photoemission from molecular orbitals can be transformed to real-space orbitals via an iterative procedure which also retrieves the lost phase information. This is demonstrated with images obtained of a number of orbitals of the molecules pentacene (C22H14) and perylene-3,4,9,10-tetracarboxylic dianhydride (C24H8O6), adsorbed on silver, which are in excellent agreement with ab initio calculations. The procedure requires no a priori knowledge of the orbitals and is shown to be simple and robust. PMID:24344291

Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F Stefan; Ramsey, Michael G; Puschnig, Peter

2014-01-14

61

Detecting Wave Function Collapse Without Prior Knowledge  

E-print Network

We are concerned with the problem of detecting with high probability whether a wave function has collapsed or not, in the following framework: A quantum system with a $d$-dimensional Hilbert space is initially in state $\\psi$; with probability $0

Charles Wesley Cowan; Roderich Tumulka

2013-12-27

62

Wave propagation using bases for bandlimited functions  

Microsoft Academic Search

We develop a two-dimensional solver for the acoustic wave equation with spatially varying coefficients. In what is a new approach, we use a basis of approximate prolate spheroidal wavefunctions and construct derivative operators that incorporate boundary and interface conditions. Writing the wave equation as a first-order system, we evolve the equation in time using the matrix exponential. Computation of the

G. Beylkin; K. Sandberg

2003-01-01

63

Effect of Forcing Function on Nonlinear Acoustic Standing Waves  

NASA Technical Reports Server (NTRS)

Nonlinear acoustic standing waves of high amplitude have been demonstrated by utilizing the effects of resonator shape to prevent the pressure waves from entering saturation. Experimentally, nonlinear acoustic standing waves have been generated by shaking an entire resonating cavity. While this promotes more efficient energy transfer than a piston-driven resonator, it also introduces complicated structural dynamics into the system. Experiments have shown that these dynamics result in resonator forcing functions comprised of a sum of several Fourier modes. However, previous numerical studies of the acoustics generated within the resonator assumed simple sinusoidal waves as the driving force. Using a previously developed numerical code, this paper demonstrates the effects of using a forcing function constructed with a series of harmonic sinusoidal waves on resonating cavities. From these results, a method will be demonstrated which allows the direct numerical analysis of experimentally generated nonlinear acoustic waves in resonators driven by harmonic forcing functions.

Finkheiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh; Daniels, Chris; Steinetz, Bruce

2003-01-01

64

Impact Localization Using Lamb Wave and Spiral FSAT  

NASA Astrophysics Data System (ADS)

Wear and tear exists in almost every physical infrastructure. Modern day science has something in its pocket to early detect such wear and tear known as Structural Health Monitoring (SHM). SHM features a key role in tracking a structural failure and could prevent loss of human lives and money. The size and prices of presently available defect detection devices make them not suitable for on-site SHM. The exploitation of directional transducers and Lamb wave propagation for SHM has been proposed. The basis of the project was to develop an accurate localization algorithm and implementation of Lamb waves to detect the crack present in the plate like structures. In regards, the use of Frequency Steerable Acoustic Transducer (FSAT) was studied. The theory governing the propagation of Lamb wave was reviewed. The derivation of the equations and dispersion curve of Lamb waves are included. FSAT was studied from both theoretical and application view of point. The experiments carried out give us better understanding of the FSAT excitation and Lamb wave generation and detection. The Lamb wave generation and crack localization algorithm was constructed and with the proposed algorithm, simulated impacts are detected.

Rimal, Nischal

65

Deep inelastic scattering and light-cone wave functions  

SciTech Connect

In the framework of light-cone QCD rules, we study the valence quark distribution function {ital q}({ital x}{sub B}) of a pion for moderate {ital x}{sub B}. The sum rule with the leading twist-2 wave function gives {ital q}({ital x}{sub B}) = {phi}{sub {pi}}({ital x}{sub B}). Twist-4 wave functions give about 30% for {ital x}{sub B} {approx}0.5. It is shown that QCD sum rule predictions, with the asymptotic pion wave function, are in good agreement with experimental data. We found that a two-hump profile for the twist-2 wave function leads to a valence quark distribution function that contradicts experimental data.

Belyaev, V.M. [ITEP, Moscow (Russia); Johnson, M.B. [Los Alamos National Lab., NM (United States)

1996-09-01

66

Symmetry-projected wave functions in quantum Monte Carlo calculations  

NASA Astrophysics Data System (ADS)

We consider symmetry-projected Hartree-Fock trial wave functions in constrained-path Monte Carlo (CPMC) calculations. Previous CPMC calculations have mostly employed Hartree-Fock (HF) trial wave functions, restricted or unrestricted. The symmetry-projected HF approach results in a hierarchy of wave functions with increasing quality: the more symmetries that are broken and restored in a self-consistent manner, the higher the quality of the trial wave function. This hierarchy is approximately maintained in CPMC calculations: the accuracy in the energy increases and the statistical variance decreases when further symmetries are broken and restored. Significant improvement is achieved in CPMC with the best symmetry-projected trial wave functions over those from simple HF. We analyze and quantify the behavior using the two-dimensional repulsive Hubbard model as an example. In the sign-problem-free region, where CPMC can be made exact but a constraint is deliberately imposed here, spin-projected wave functions remove the constraint bias. Away from half filling, spatial symmetry restoration in addition to that of the spin leads to highly accurate results from CPMC. Since the computational cost of symmetry-projected HF trial wave functions in CPMC can be made to scale algebraically with system size, this provides a potentially general approach for accurate calculations in many-fermion systems.

Shi, Hao; Jiménez-Hoyos, Carlos A.; Rodríguez-Guzmán, R.; Scuseria, Gustavo E.; Zhang, Shiwei

2014-03-01

67

Boundary conditions on internal three-body wave functions  

SciTech Connect

For a three-body system, a quantum wave function {Psi}{sub m}{sup {ell}} with definite {ell} and m quantum numbers may be expressed in terms of an internal wave function {chi}{sub k}{sup {ell}} which is a function of three internal coordinates. This article provides necessary and sufficient constraints on {chi}{sub k}{sup {ell}} to ensure that the external wave function {Psi}{sub k}{sup {ell}} is analytic. These constraints effectively amount to boundary conditions on {chi}{sub k}{sup {ell}} and its derivatives at the boundary of the internal space. Such conditions find similarities in the (planar) two-body problem where the wave function (to lowest order) has the form r{sup |m|} at the origin. We expect the boundary conditions to prove useful for constructing singularity free three-body basis sets for the case of nonvanishing angular momentum.

Mitchell, Kevin A.; Littlejohn, Robert G.

1999-10-01

68

Dark energy from quantum wave function collapse of dark matter  

E-print Network

Dynamical wave function collapse models entail the continuous liberation of a specified rate of energy arising from the interaction of a fluctuating scalar field with the matter wave function. We consider the wave function collapse process for the constituents of dark matter in our universe. Beginning from a particular early era of the universe chosen from physical considerations, the rate of the associated energy liberation is integrated to yield the requisite magnitude of dark energy around the era of galaxy formation. Further, the equation of state for the liberated energy approaches $w \\to -1$ asymptotically, providing a mechanism to generate the present acceleration of the universe.

A. S. Majumdar; D. Home; S. Sinha

2009-09-03

69

Asymptotic wave function for three charged particles in the continuum  

NASA Astrophysics Data System (ADS)

We present an improved version of the wave function derived by Alt and Mukhamedzhanov [Phys. Rev. A 47, 2004 (1993)] that satisfies the Schrödinger equation up to terms of order O(1/?2?) in the region where the pair ?=(?,?) remains close, while the third particle ? moves to infinity (??-->?). The new wave function contains the zeroth- and all the first-order O(1/??) terms, and matches smoothly Redmond's asymptotics and the Redmond-Merkuriev wave function when all three particles are well separated.

Mukhamedzhanov, A. M.; Lieber, M.

1996-10-01

70

Angular correlation function and scattering coefficient of electromagnetic waves  

E-print Network

Angular correlation function and scattering coefficient of electromagnetic waves scattered We study three-dimensional (3-D) electromagnetic wave scattering from a buried object under a two. The study of 3-D electromagnetic scattering allows the use of azimuthal angular averaging and the study

Zhang, Guifu

71

Impact of sea-level rise and coral mortality on the wave dynamics and wave forces on barrier reefs.  

PubMed

A one-dimensional wave model was used to investigate the reef top wave dynamics across a large suite of idealized reef-lagoon profiles, representing barrier coral reef systems under different sea-level rise (SLR) scenarios. The modeling shows that the impacts of SLR vary spatially and are strongly influenced by the bathymetry of the reef and coral type. A complex response occurs for the wave orbital velocity and forces on corals, such that the changes in the wave dynamics vary reef by reef. Different wave loading regimes on massive and branching corals also leads to contrasting impacts from SLR. For many reef bathymetries, wave orbital velocities increase with SLR and cyclonic wave forces are reduced for certain coral species. These changes may be beneficial to coral health and colony resilience and imply that predicting SLR impacts on coral reefs requires careful consideration of the reef bathymetry and the mix of coral species. PMID:24768171

Baldock, T E; Golshani, A; Callaghan, D P; Saunders, M I; Mumby, P J

2014-06-15

72

Nodes of entangled N-particle wave functions  

SciTech Connect

In a recent paper [Bressanini et al. Phys. Rev. Lett. 95, 110201 (2005)] it was pointed out that 'the nodes of even simple wave functions are largely unexplored'. Here we show that for N-particle wave functions nodal surfaces arise from the spin and orbital entanglement of constituent two-particle wave functions and derive, for two-electron atoms, 11 exact nodal rules applicable in LS coupling. In addition, the 'higher symmetry' identified numerically in the above paper is shown to be an approximate dynamical symmetry described by a molecular model or a classical unstable periodic orbit. We show that the analysis is readily extended to four-particle wave functions and consider the case of the hydrogen molecule, both fixed in space and rotating.

Briggs, John S. [Theoretische Quantendynamik, Universitaet Freiburg, D-79104 Freiburg (Germany); Walter, Michael [Department of Physics, Nanoscience Center, University of Jyvaeskylae, Jyvaeskylae FIN-40014 (Finland)

2006-12-15

73

New approach for approximating the continuum wave function by Gaussian basis set  

NASA Astrophysics Data System (ADS)

A new approach for approximating the continuum wave functions for hydrogenic atoms with Gaussians basis sets is developed and tested. In this the plane wave is left unchanged and the distorting factor, represented by the Confluent Hypergeometric function, is expanded as a sum of Spherical Harmonics multiplied by a series of Gaussians. In this way the number of spherical waves and Gaussians will be significantly reduced and the plane wave will be responsible for the momentum conservation. As compared with previous methods that expand the full continuum, including the plane wave, our strategy does not require a great quantity of partial waves for convergence. Dense oscillations which are characteristic of the plane wave, are avoided. To test the performance of this approximation to describe a free-bound atomic form factor, the ionization cross section of hydrogen by impact of protons in first Born approximation is calculated. Compared with the exact results, a good agreement with just 4 spherical waves and ten Gaussians each is obtained. The method looks very interesting, especially to speed up atomic and molecular collision calculations involving the continuum.

Fiori, Marcelo; Miraglia, J. E.

2012-12-01

74

Wavelets Based on ProlateSpheroidal Wave Functions  

Microsoft Academic Search

The article is concerned with a particular multiresolution analysis (MRA) composed of Paley–Wiener spaces. Their usual wavelet basis consisting of sinc functions is replaced by one based on prolate spheroidal wave functions (PSWFs) which have much better time localization than the sinc function. The new wavelets preserve the high energy concentration in both the time and frequency domain inherited from

Gilbert G. Walter; Xiaoping Shen

2004-01-01

75

Influence of Superpositional Wave Function Oscillations on Shor's Quantum Algorithm  

SciTech Connect

We investigate the influence of superpositional wave function oscillations on the performance of Shor's quantum algorithm for factorization of integers. It is shown that wave function oscillations can modify the required quantum interference. This undesirable effect can be routinely eliminated using a resonant pulse implementation of quantum computation, but requires special analysis for nonresonant implementations. We also discuss the influence of this effect on implementation of other quantum algorithms. (c) 2000 The American Physical Society.

Berman, Gennady P. [Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Doolen, Gary D. [Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Tsifrinovich, Vladimir I. [IDS Department, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201 (United States)] [IDS Department, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201 (United States)

2000-02-14

76

Asymptotic continuum wave function for three charged particles  

NASA Astrophysics Data System (ADS)

We present the asymptotic solution of the Schrödinger equation for three charged particles in the region ?? in which ??-->? and r??/??-->0, where r?? is the distance between particles ? and ?, and ?? is the distance between particle ? and the center of mass of the pair (?,?) (?????). Our asymptotic wave function in ?? satisfies the Schrödinger equation up to terms of order O(1/?2?) and contains the zeroth-order terms and all of the first-order O(1/??) terms. The new wave function contains additional terms which are absent in previous wave functions derived recently by others. The additional terms can be expressed in terms of solutions of a two-body problem with boundary conditions which do not correspond to the conventional boundary conditions for two-body states. We also prove that the leading term of our asymptotic wave function in ?? is equal to the leading term of the Redmond-Merkuriev (RM) wave function in ??, and hence the RM wave function is applicable in regions of ?? (?=1,2,3) up to terms of order O(1/??).

Kim, Y. E.; Zubarev, A. L.

1997-07-01

77

Impact of high-frequency nonlinear internal waves on plankton dynamics in Massachusetts Bay  

E-print Network

Impact of high-frequency nonlinear internal waves on plankton dynamics in Massachusetts Bay-Volume Coastal Ocean Model (FVCOM-NH) to study the impact of high- frequency nonlinear internal waves on plankton: (I) hydraulic jump; (II) strong internal wave-tidal current nonlinear interaction; and (III

Chen, Changsheng

78

Impact of boat-generated waves on intertidal estuarine sediments  

NASA Astrophysics Data System (ADS)

Hydrodynamics in the macrotidal Seine estuary (France) are controlled by the semi-diurnal tidal regime modulated seasonally by the fluvial discharge. Wind effect on sediment transport (through wind waves and swell) is observed at the mouth of the estuary. Over the last century, authorities have put emphasis on facilitating economic exchanges by means of embankment building and increased dredging activity. These developments led to allow and secure sea vessel traffic in the Seine estuary (from its mouth to the port of Rouen, 125 km upstream) but they also resulted in a change of estuarine hydrodynamics and sediment transport features. A riversides restoration policy has been recently started by port authorities. In this context, the objective of the field-based study presented is to connect vessel characteristics (i.e. speed, draft...), boat-generated waves and their sedimentary impacts. Such information will be used by stakeholders to manage riverside. The natural intertidal site of interest is located in the fluvial freshwater part of the Seine estuary characterized by a 4.5 m maximum tidal range. The foreshore slope is gently decreasing and surface sediments are composed of fine to coarse sand with occasional mud drapes. In order to decipher boat-generated events, the sampling strategy is based on continuous ADV measurements coupled with a turbidimeter and an altimeter to study sediment dynamics. These instruments are settled in the lower part of the foreshore (i) to obtain a significant dataset (i.e. oceanic instruments are not measuring in air) on a zone statically affected by boat waves and (ii) because most of boat traffic occurs during early flood or late ebb period. Spatial variations are assessed along a cross-section through grain-size analysis of surface sediments and topography measurements using pole technique. Results enhance hydrodynamic and sedimentary impacts of boat-generated waves compared respectively to tidal and wind effects. Long-term altimeter measurements in relation with boat traffic data base demonstrate that boat-generated waves are the key hydrodynamic parameter controlling short term tidal flat evolution. Concerning hydrodynamics, two main types of boat-generated waves can be distinguished: one corresponds to barges, the other to sea vessels. The critical parameter controlling wave characteristics, bottom shear stress and thus sedimentary impacts is the distance between seabed and keel. Thus, considering their larger seabed-keel distance, barges do not significantly affect the sedimentary cover of the intertidal area. On the contrary, sea-vessels can induce rapid changes of the tidal flat texture (i.e. bed flattening, mud drapes...) and morphology: erosion and sedimentation rates in a range of 0.5 to 6 cm.min-1 have been measured. Such energetic events occur generally during the squat generated wave run-up and can affect the seabed in water depths up to 1.5 m. In the freshwater part of the Seine estuary annual sediment inputs are mostly controlled by river flow (during river flood) while medium term scale evolution is dependent on tidal range and short term sediment dynamics (i.e. bedload, resuspension) on sea-vessels waves.

Blanpain, O.; Deloffre, J.; Lafite, R.; Gomit, G.; Calluaud, D.; David, L.

2010-12-01

79

Can the wave function in configuration space be replaced by single-particle wave functions in physical space?  

E-print Network

The ontology of Bohmian mechanics includes both the universal wave function (living in 3N-dimensional configuration space) and particles (living in ordinary 3-dimensional physical space). Proposals for understanding the physical significance of the wave function in this theory have included the idea of regarding it as a physically-real field in its 3N-dimensional space, as well as the idea of regarding it as a law of nature. Here we introduce and explore a third possibility in which the configuration space wave function is simply eliminated -- replaced by a set of single-particle pilot-wave fields living in ordinary physical space. Such a re-formulation of the Bohmian pilot-wave theory can exactly reproduce the statistical predictions of ordinary quantum theory. But this comes at the rather high ontological price of introducing an infinite network of interacting potential fields (living in 3-dimensional space) which influence the particles' motion through the pilot-wave fields. We thus introduce an alternative approach which aims at achieving empirical adequacy (like that enjoyed by GRW type theories) with a more modest ontological complexity, and provide some preliminary evidence for optimism regarding the (once popular but prematurely-abandoned) program of trying to replace the (philosophically puzzling) configuration space wave function with a (totally unproblematic) set of fields in ordinary physical space.

Travis Norsen; Damiano Marian; Xavier Oriols

2014-10-14

80

A NOTE ON PROLATE SPHEROIDAL WAVE FUNCTIONS AND PROLATE FUNCTION BASED NUMERICAL INVERSION METHODS  

Microsoft Academic Search

Polynomials are one of most important and widely used numerical tools in dealing with a smooth function on a bounded domain and trigonometric functions work for smooth periodic functions. However, they are not the best choice if a function has a bounded support in space and in frequency domain. The Prolate Spheroidal wave function (PSWF) of order zero has been

EUNJOO KIM; JUNE-YUB LEEy

2008-01-01

81

Rapidity resummation for B-meson wave functions  

NASA Astrophysics Data System (ADS)

Transverse-momentum dependent (TMD) hadronic wave functions develop light-cone divergences under QCD corrections, which are commonly regularized by the rapidity ? of gauge vector defining the non-light-like Wilson lines. The yielding rapidity logarithms from infrared enhancement need to be resummed for both hadronic wave functions and short-distance functions, to achieve scheme-independent calculations of physical quantities. We briefly review the recent progress on the rapidity resummation for B-meson wave functions which are the key ingredients of TMD factorization formulae for radiative-leptonic, semi-leptonic and non-leptonic B-meson decays. The crucial observation is that rapidity resummation induces a strong suppression of B-meson wave functions at small light-quark momentum, strengthening the applicability of TMD factorization in exclusive B-meson decays. The phenomenological consequence of rapidity-resummation improved B-meson wave functions is further discussed in the context of B ? ? transition form factors at large hadronic recoil.

Shen, Yue-Long; Wang, Yu-Ming

2014-11-01

82

Inside looking out: Probing JIMWLK wave functions with BFKL calculations  

SciTech Connect

We investigate the relation between the eigenvalues and eigenfunctions of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) and Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner (JIMWLK/KLWMIJ) Hamiltonians. We show that the eigenvalues of the BFKL Hamiltonians are also exact eigenvalues of the KLWMIJ (and JIMWLK) Hamiltonian, albeit corresponding to possibly non-normalizable eigenfunctions. The question whether a given eigenfunction of BFKL corresponds to a normalizable eigenfunction of KLWMIJ is rather complicated, except in some obvious cases, and requires independent investigation. As an example to illustrate this relation we concentrate on the color octet exchange in the framework of KLWMIJ Hamiltonian. We show that it corresponds to the reggeized gluon exchange of BFKL, and find first correction to the BFKL wave function, which has the meaning of the impact factor for shadowing correction to the Reggeized gluon. We also show that the bootstrap condition in the KLWMIJ framework is satisfied automatically and does not carry any additional information to that contained in the second quantized structure of the KLWMIJ Hamiltonian. This is an example of how the bootstrap condition inherent in the t-channel unitarity arises in the s-channel picture.

Altinoluk, Tolga; Kovner, Alex [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, Connecticut 06269 (United States); Levin, Eugene [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Casilla 110-V, Valparaiso (Chile); Department of Particle Physics, Tel Aviv University, Tel Aviv 69978 (Israel)

2010-10-01

83

Analysis of spectral approximations using prolate spheroidal wave functions  

Microsoft Academic Search

In this paper, the approximation properties of the prolate spheroidal wave functions of order zero (PSWFs) are studied, and a set of optimal error estimates are derived for the PSWF approximation of non-periodic functions in Sobolev spaces. These results serve as an indispensable tool for the analysis of PSWF spectral methods. A PSWF spectral-Galerkin method is proposed and analyzed for

Li-Lian Wang

2010-01-01

84

Impact of damage on propagation of Lamb waves in plates  

NASA Astrophysics Data System (ADS)

A consorted effort is ongoing to utilize spectral analysis of Lamb Waves to rapidly characterize and to detect damage in plates. To optimize test set-up, to understand the limitations of the methodology, and to verify the experimental results, an effort is under way to simulate conditions normally encountered in actual cases. The impact of propagation of Lamb waves in the presence or absence of damage has been simulated using a finite element algorithm, 2D Fourier transform can be used to identify individual modes, and to measure the amplitude and propagation velocity of each mode in a thin plate. Mode conversion due to the presence of a crack can be readily identified with this method. The damage was modeled as notches with different widths and depths. Three different materials were modeled for this purpose: Aluminum 6061-T6, Steel A36, and Graphite- Epoxy; the latter being analyzed in directions parallel nd perpendicular to the fibers. The focus of the work was on low-frequency range where the fundamental symmetric and anti-symmetric modes are dominant. The ratio of notch depth to plate thickness and the absolute notch depth were considered as possible controlling parameters for the sensitivity in the damage detection. The effect of the width of the flaw on the transmissivity of the Lamb waves was also considered and found to be minimal.

Tirado, Cesar; Nazarian, Soheil

1999-01-01

85

Helicon Wave Physics Impacts on Electrodeless Thruster Design  

NASA Technical Reports Server (NTRS)

Effective generation of helicon waves for high density plasma sources is determined by the dispersion relation and plasma power balance. Helicon wave plasma sources inherently require an applied magnetic field of .01-0.1 T, an antenna properly designed to couple to the helicon wave in the plasma, and an rf power source in the 10-100 s of MHz, depending on propellant choice. For a plasma thruster, particularly one with a high specific impulse (>2000 s), the physics of the discharge would also have to address the use of electron cyclotron resonance (ECR) heating and magnetic expansion. In all cases the system design includes an optimized magnetic field coil, plasma source chamber, and antenna. A preliminary analysis of such a system, calling on experimental data where applicable and calculations where required, has been initiated at Glenn Research Center. Analysis results showing the mass scaling of various components as well as thruster performance projections and their impact on thruster size are discussed.

Gilland, James

2003-01-01

86

Spin and the Thermal Equilibrium Distribution of Wave Functions  

E-print Network

Consider a quantum system $S$ weakly interacting with a very large but finite system $B$ called the heat bath, and suppose that the composite $S\\cup B$ is in a pure state $\\Psi$ with participating energies between $E$ and $E+\\delta$ with small $\\delta$. Then, it is known that for most $\\Psi$ the reduced density matrix of $S$ is (approximately) equal to the canonical density matrix. That is, the reduced density matrix is universal in the sense that it depends only on $S$'s Hamiltonian and the temperature but not on $B$'s Hamiltonian, on the interaction Hamiltonian, or on the details of $\\Psi$. It has also been pointed out that $S$ can also be attributed a random wave function $\\psi$ whose probability distribution is universal in the same sense. This distribution is known as the "Scrooge measure" or "Gaussian adjusted projected (GAP) measure"; we regard it as the thermal equilibrium distribution of wave functions. The relevant concept of the wave function of a subsystem is known as the "conditional wave function". In this paper, we develop analogous considerations for particles with spin. One can either use some kind of conditional wave function or, more naturally, the "conditional density matrix", which is in general different from the reduced density matrix. We ask what the thermal equilibrium distribution of the conditional density matrix is, and find the answer that for most $\\Psi$ the conditional density matrix is (approximately) deterministic, in fact (approximately) equal to the canonical density matrix.

Viraj Pandya; Roderich Tumulka

2013-06-07

87

Correlated continuum wave functions for three particles with Coulomb interactions  

NASA Astrophysics Data System (ADS)

We present an approximate solution of the Schröautdinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms of the Hamiltonian that before had been considered as a perturbation. Its solution can be expressed in terms of a confluent hypergeometric function of two variables. We show that the proposed wave function includes a correlation between the motion of the light particle relative to the heavy particles and verifies the correct asymptotic behavior when all particles are far from each other. Finally, we discuss the possible uses of this function in the calculation of transition matrices and differential cross sections in ionizing collisions.

Gasaneo, G.; Colavecchia, F. D.; Garibotti, C. R.; Miraglia, J. E.; Macri, P.

1997-04-01

88

Monitoring the wave function by time continuous position measurement  

E-print Network

We consider a single copy of a quantum particle moving in a potential and show that it is possible to monitor its complete wave function by only continuously measuring its position. While we assume that the potential is known, no information is available about its state initially. In order to monitor the wave function, an estimate of the wave function is propagated due to the influence of the potential and continuously updated according to the results of the position measurement. We demonstrate by numerical simulations that the estimation reaches arbitrary values of accuracy below 100 percent within a finite time period for the potentials we study. In this way our method grants, a certain time after the beginning of the measurement, an accurate real-time record of the state evolution including the influence of the continuous measurement. Moreover, it is robust against sudden perturbations of the system as for example random momentum kicks from environmental particles, provided they occur not too frequently.

Konrad, Thomas; Petruccione, Francesco; Diósi, Lajos

2009-01-01

89

Impact of autocorrelation on functional connectivity.  

PubMed

Although the impact of serial correlation (autocorrelation) in residuals of general linear models for fMRI time-series has been studied extensively, the effect of autocorrelation on functional connectivity studies has been largely neglected until recently. Some recent studies based on results from economics have questioned the conventional estimation of functional connectivity and argue that not correcting for autocorrelation in fMRI time-series results in "spurious" correlation coefficients. In this paper, first we assess the effect of autocorrelation on Pearson correlation coefficient through theoretical approximation and simulation. Then we present this effect on real fMRI data. To our knowledge this is the first work comprehensively investigating the effect of autocorrelation on functional connectivity estimates. Our results show that although FC values are altered, even following correction for autocorrelation, results of hypothesis testing on FC values remain very similar to those before correction. In real data we show this is true for main effects and also for group difference testing between healthy controls and schizophrenia patients. We further discuss model order selection in the context of autoregressive processes, effects of frequency filtering and propose a preprocessing pipeline for connectivity studies. PMID:25072392

Arbabshirani, Mohammad R; Damaraju, Eswar; Phlypo, Ronald; Plis, Sergey; Allen, Elena; Ma, Sai; Mathalon, Daniel; Preda, Adrian; Vaidya, Jatin G; Adali, Tülay; Calhoun, Vince D

2014-11-15

90

Canonical Transformation of a Classical Wave to Generate a Complex Wave Function  

NASA Astrophysics Data System (ADS)

Canonical transformation (CT) of a classical field, such as the real wave function of an elastic wave, has not been well explored. A modification of the usual form of Hamiltonian density is possible such that it will lend itself readily to CT. The procedure is as follows: (1) Write down the integral with the usual H.density as the integrand - i.e. the action. (2) Integrate by part the potential energy part of H, density.(3) Fourier transform ( or more general expansion) the wave function. (4) Square-complete the integrand of (2), making use of the orthogality of Fourier terms. Then the new integrand is the equivalent of the old as an H. density. It will have the correct properties that are expected of the probability density function ( Provided it is normalied) It can be shown that the canonical variables obtained from the CT is more proper and correct than the usual psy function appearing in the first order wave equation in quantum mechanics. The difference between the two methods becomes manifest when one deals with a nonconservative system. It therefore justifies Schroedinger's insistence on the use of a real wave function.

Chen, Robert L. W.

2001-04-01

91

Diving-wave migration using Airy functions  

SciTech Connect

A method is described for imaging seismic reflection data selected from a data volume, comprising: preprocessing said selected seismic reflection data by application of normal moveout, dip moveout and a time-domain-to-frequency-domain transformation; determining the velocity field characteristic of said data volume; forming a velocity model for said data volume by fitting a velocity function to said velocity field, said function being characterized by a linear gradient in sloth; from the velocity model, calculating parameters for defining an Airy operator; separating normal seismic data from evanescent seismic data and saving said evanescant data in a random access memory; iterating downwardly, migrating said normal seismic data with the aid of said Airy operator; extracting said evanescent data from memory and iterating upwardly, migrating said evanescent seismic data with the aid of said Airy operator; summing the results of the downward and upward iterations; and inversely Fourier-transforming the summation.

Albertin, U.K.

1993-08-10

92

Local effective potential theory: nonuniqueness of potential and wave function.  

PubMed

In local effective potential energy theories such as the Hohenberg-Kohn-Sham density functional theory (HKS-DFT) and quantal density functional theory (Q-DFT), electronic systems in their ground or excited states are mapped to model systems of noninteracting fermions with equivalent density. From these models, the equivalent total energy and ionization potential are also obtained. This paper concerns (i) the nonuniqueness of the local effective potential energy function of the model system in the mapping from a nondegenerate ground state, (ii) the nonuniqueness of the local effective potential energy function in the mapping from a nondegenerate excited state, and (iii) in the mapping to a model system in an excited state, the nonuniqueness of the model system wave function. According to nondegenerate ground state HKS-DFT, there exists only one local effective potential energy function, obtained as the functional derivative of the unique ground state energy functional, that can generate the ground state density. Since the theorems of ground state HKS-DFT cannot be generalized to nondegenerate excited states, there could exist different local potential energy functions that generate the excited state density. The constrained-search version of HKS-DFT selects one of these functions as the functional derivative of a bidensity energy functional. In this paper, the authors show via Q-DFT that there exist an infinite number of local potential energy functions that can generate both the nondegenerate ground and excited state densities of an interacting system. This is accomplished by constructing model systems in configurations different from those of the interacting system. Further, they prove that the difference between the various potential energy functions lies solely in their correlation-kinetic contributions. The component of these functions due to the Pauli exclusion principle and Coulomb repulsion remains the same. The existence of the different potential energy functions as viewed from the perspective of Q-DFT reaffirms that there can be no equivalent to the ground state HKS-DFT theorems for excited states. Additionally, the lack of such theorems for excited states is attributable to correlation-kinetic effects. Finally, they show that in the mapping to a model system in an excited state, there is a nonuniqueness of the model system wave function. Different wave functions lead to the same density, each thereby satisfying the sole requirement of reproducing the interacting system density. Examples of the nonuniqueness of the potential energy functions for the mapping from both ground and excited states and the nonuniqueness of the wave function are provided for the exactly solvable Hooke's atom. The work of others is also discussed. PMID:17552753

Sahni, Viraht; Slamet, Marlina; Pan, Xiao-Yin

2007-05-28

93

Singlet wave functions for the t-J model  

NASA Astrophysics Data System (ADS)

We investigate T=0 properties of the commensurate flux phases, a class of variational wave functions for the t-J model proposed recently by Anderson, Shastry, and Hristopoulos and which generalize the (1/2-flux state of Affleck and Marston away from half-filling. These states can be formally written in the quantum spin liquid form, the singlet bond amplitudes of which break the lattice translational symmetry. The supercell of the electromagnetic gauge (defining the fictitious flux) imposes the actual periodicities of the correlated wave function. Their order of commensurability with the lattice unit length is closely related to the hole density.

Poilblanc, D.

1989-10-01

94

Optimal multiconfiguration approximation of an N-fermion wave function  

NASA Astrophysics Data System (ADS)

We propose a simple iterative algorithm to construct the optimal multiconfiguration approximation of an N-fermion wave function. Namely, M ?N single-particle orbitals are sought iteratively so that the projection of the given wave function in the CMN-dimensional configuration subspace is maximized. The algorithm has a monotonic convergence property and can be easily parallelized. The significance of the algorithm on the study of geometric entanglement in a multifermion system and its implication on the multiconfiguration time-dependent Hartree-Fock (MCTDHF) are discussed. The ground state and real-time dynamics of spinless fermions with nearest-neighbor interaction are studied using this algorithm, discussing several subtleties.

Zhang, J. M.; Kollar, Marcus

2014-01-01

95

Evolution of wave function in a dissipative system  

NASA Technical Reports Server (NTRS)

For a dissipative system with Ohmic friction, we obtain a simple and exact solution for the wave function of the system plus the bath. It is described by the direct product in two independent Hilbert space. One of them is described by an effective Hamiltonian, the other represents the effect of the bath, i.e., the Brownian motion, thus clarifying the structure of the wave function of the system whose energy is dissipated by its interaction with the bath. No path integral technology is needed in this treatment. The derivation of the Weisskopf-Wigner line width theory follows easily.

Yu, Li-Hua; Sun, Chang-Pu

1994-01-01

96

Many-body wave function in a dipole blockade configuration  

SciTech Connect

We report the results of simulations of the many atom wave function when a cold gas is excited to highly excited states. We simulated the many body wave function by direct numerical solution of Schroedinger's equation. We investigated the fraction of atoms excited and the correlation of excited atoms in the gas for different types of excitation when the blockade region was small compared to the sample size. We also investigated the blockade effect when the blockade region is comparable to the sample size to determine the sensitivity of this system and constraints for quantum information.

Robicheaux, F.; Hernandez, J. V. [Department of Physics, Auburn University, Alabama 36849-5311 (United States)

2005-12-15

97

Sign problem of the fermionic shadow wave function.  

PubMed

We present a whole series of methods to alleviate the sign problem of the fermionic shadow wave function in the context of variational Monte Carlo. The effectiveness of our techniques is demonstrated on liquid ^{3}He. We found that although the variance is reduced, the gain in efficiency is restricted by the increased computational cost. Yet, this development not only extends the scope of the fermionic shadow wave function, but also facilitates highly accurate quantum Monte Carlo simulations previously thought not feasible. PMID:25493901

Calcavecchia, Francesco; Pederiva, Francesco; Kalos, Malvin H; Kühne, Thomas D

2014-11-01

98

Impact of improved wave dissipation parameterisations on wave-current interactions in a coupled wave-ocean model  

NASA Astrophysics Data System (ADS)

The WAVEWATCH-III model is used operationally as part of the PREVIMER coastal forecast system. A global version of the model provides boundary conditions for a series of stand-alone high-resolution regional sub-domains, on unstructured grids, which are coupled with the regional ocean model MARS. New developments in the WW3 model include a combination of dissipation parameterisations (Ardhuin et al 2010). An anisotropic breaking-induced wind wave dissipation has been based on the local saturation spectrum, with a higher dissipation rate in the mean wave direction, designed to fit observed directional spreading. Additionally, a cumulative dissipation rate inspired by Babanin and Young (2005) but directly estimated from breaking wave probabilities dramatically enhances the dissipation at frequencies greater than 3 times the peak frequency. Regarding swell, a non-linear dissipation based on SAR-derived dissipation rates across the Pacific (Ardhuin et al., 2009) has been introduced. Validation of this model (Rascle and Ardhuin 2012, submitted) using a global hindcast from 1994-2010 shows improvements in significant wave height compared to an altimeter database, with values <10% in general. Regarding extreme events, Hanafin et al (2012) showed that the prediction of the timing of arrival, peak period and spectral distribution of very long swell generated by hurricane-level winds in the North Atlantic compared very well to coastal buoy observations. One of the aims of such improvements is to assist users by providing better geophysical parameters as output. Improvements noted in the mean squared slope compared to buoys, for example, implies a larger amount of energy is available to near-surface Langmuir turbulence. A recent study using the WW3 wave model and the MARS ocean model (Ardhuin et al, in press, JPO 2012) focused on near-shore wave interaction with strong currents. At small scales, rapid steepening of wave slopes by opposing currents induces enhanced breaking as the group velocity decreases. In the study area, tidal currents of up to 4m/s which are highly coherent over the water column and a high wind event created excellent conditions to test the performance of the model. A surface current radar with a resolution of 1km due to multiple signal classification algorithm and a number of buoys were used for validation. Adding currents in the wave model reduced the errors by up to 30% and clearly showed the effects of wave trapping by the strong tidal currents. Comparing different dissipation parameterisations, however, showed that none were completely satisfactory, indicating that further research is required in this area. For short wind waves, the relative wind at the air-sea interface becomes an important factor. At larger scales, waves are refracted by currents. In these cases, the choice of dissipation parameterisation was found to be less important when only one partition was present, though Ardhuin et al (2010) showed better results in mixed seas. Tidal modulations were shown to be due to currents, rather than water level, and a large impact was observed down-wave of currents that have large refraction effects as well as in the vicinity of the currents.

Hanafin, J. A.; Ardhuin, F.; Roland, A.; Leckler, F.; Rascle, N.

2012-12-01

99

Dielectrically embedded mesh half wave plate beam impact studies  

NASA Astrophysics Data System (ADS)

An alternative solution to classic birefringent Half Wave Plates (HWP), based on the photolithographic techniques, has been recently developed. This new device can offer a very good alternative as a polarisation modulator for future CMB polarisation instruments. However, the systematic effects that this HWP will introduce in the overall instrument need to be investigated. We present a preliminary study of the impact of this dielectrically embedded HWP on the beam shape of a corrugated horn and its performance across the beam. Using a W-band Vector Network Analyser, we measured the co- and crosspolarisation beams of the HWP-horn system and the differential phase-shift introduced by the HWP across the beam.

Maffei, B.; Pisano, G.; Ng, M. W.; Haynes, V. C.

2012-09-01

100

Chiral exciton wave functions in cylindrical J aggregates.  

PubMed

We study the exciton wave functions and the optical properties of cylindrical molecular aggregates. The cylindrical symmetry allows for a decomposition of the exciton Hamiltonian into a set of effective one-dimensional Hamiltonians, characterized by a transverse wave number k2. These effective Hamiltonians have interactions that are complex if the cylinder exhibits chirality. We propose analytical ansatze for the eigenfunctions of these one-dimensional problems that account for a finite cylinder length, and present a general study of their validity. A profound difference is found between the Hamiltonian for the transverse wave number k2=0 and those with k2 not equal 0. The complex nature of the latter leads to chiral wave functions, which we characterize in detail. We apply our general formalism to the chlorosomes of green bacteria and compare the wave functions as well as linear optical spectra (absorption and dichroism) obtained through our ansätze with those obtained by numerical diagonalization as well as those obtained by imposing periodic boundary conditions in the cylinder's axis direction. It is found that our ansätze, in particular, capture the finite-length effect in the circular dichroism spectrum much better than the solution with periodic boundary conditions. Our ansätze also show that in finite-length cylinders seven superradiant states dominate the linear optical response. PMID:15260627

Didraga, Catalin; Knoester, Jasper

2004-07-01

101

Impact of american-style football participation on vascular function.  

PubMed

Although hypertension is common in American-style football (ASF) players, the presence of concomitant vascular dysfunction has not been previously characterized. We sought to examine the impact of ASF participation on arterial stiffness and to compare metrics of arterial function between collegiate ASF participants and nonathletic collegiate controls. Newly matriculated collegiate athletes were studied longitudinally during a single season of ASF participation and were then compared with healthy undergraduate controls. Arterial stiffness was characterized using applanation tonometry (SphygmoCor). ASF participants (n = 32, 18.4 ± 0.5 years) were evenly comprised of Caucasians (n = 14, 44%) and African-Americans (n = 18, 56%). A single season of ASF participation led to an increase in central aortic pulse pressure (27 ± 4 vs 34 ± 8 mm Hg, p <0.001). Relative to controls (n = 47), pulse wave velocity was increased in ASF participants (5.6 ± 0.7 vs 6.2 ± 0.9 m/s, p = 0.002). After adjusting for height, weight, body mass index, systolic blood pressure, and diastolic blood pressure, ASF participation was independently predictive of increased pulse wave velocity (? = 0.33, p = 0.04). In conclusion, ASF participation leads to changes in central hemodynamics and increased arterial stiffness. PMID:25465938

Kim, Jonathan H; Sher, Salman; Wang, Francis; Berkstresser, Brant; Shoop, James L; Galante, Angelo; Al Mheid, Ibhar; Ghasemzadeh, Nima; Hutter, Adolph M; Williams, B Robinson; Sperling, Laurence S; Weiner, Rory B; Quyyumi, Arshed A; Baggish, Aaron L

2015-01-15

102

When does nutrition impact respiratory function?  

PubMed

Nutrition therapy is an essential aspect of patient care and an important determinant of outcomes in the ICU. Nutrition can impact respiratory function in a myriad of ways. Under- and overfeeding are two well-established ways by which nutrition impinges on respiratory function. Route of feeding, method of feeding, and carbohydrate composition of the diet are also other key factors regarding nutrition that influence outcomes in ICU patients. Recent studies are now elucidating the role of immune therapy in patients with acute respiratory distress syndrome. In the ICU, nutrition dogmas, such as the necessity of checking gastric residual volumes or utilizing full-calorie enteric feeds, as opposed to trophic feeds, are constantly being challenged by innovative clinical studies. Basic research brings the prospect of testing new approaches for ICU patients, such as the use of antioxidants to prevent diaphragm weakness in these patients. In this review article, we evaluate the recent observational and randomized control trials to critically appraise the evidence regarding nutrition in the ICU. PMID:23636903

Allen, Karen S; Mehta, Ishan; Cavallazzi, Rodrigo

2013-06-01

103

Impact wave deposits provide new constraints on the location of the K/T boundary impact  

NASA Technical Reports Server (NTRS)

All available evidence is consistent with an impact into oceanic crust terminating the Cretaceous Period. Although much of this evidence is incompatible with an endogenic origin, some investigators still feel that a volcanic origin is possible for the Cretaceous/Tertiary (K/T) boundary clay layers. The commonly cited evidence for a large impact stems from delicate clay layers and their components and the impact site has not yet been found. Impact sites have been suggested all over the globe. The impact is felt to have occurred near North America by: the occurrence of a 2 cm thick ejecta layer only at North American locales, the global variation of shocked quartz grain sizes peaking in North America, the global variation of spinel compositions with most refractory compositions occurring in samples from the Pacific region and possibly uniquely severe plant extinctions in the North American region. The K/T boundary interval was investigated as preserved on the banks of the Brazos River, Texas. The K/T fireball and ejecta layers with associated geochemical anomalies were found interbedded with this sequence which apparently allows a temporal resolution 4 orders of magnitude greater than typical K/T boundary sections. A literature search reveals that such coarse deposits are widely preserved at the K/T boundary. Impact wave deposits have not been found elsewhere on the globe, suggesting the impact occurred between North and South America. The coarse deposits preserved in Deep Sea Drilling Project (DSDP) holes 151-3 suggest the impact occurred nearby. Subsequent tectonism has complicated the picture.

Hildebrand, A. R.; Boynton, W. V.

1988-01-01

104

Interpretation of the wave function of the universe  

SciTech Connect

Hawking and Hartle interpreted their wave function of the universe as giving the probability for the universe to appear from nothing. However, this is not a correct interpretation, since the normalization presupposes a universe, not nothing. Transition probabilities require a measure on the initial state and a physical result requires a physical initial state.

Drees, W.B.

1987-10-01

105

Parallel eigensolvers in plane-wave Density Functional Theory  

NASA Astrophysics Data System (ADS)

We consider the problem of parallelizing electronic structure computations in plane-wave Density Functional Theory. Because of the limited scalability of Fourier transforms, parallelism has to be found at the eigensolver level. We show how a recently proposed algorithm based on Chebyshev polynomials can scale into the tens of thousands of processors, outperforming block conjugate gradient algorithms for large computations.

Levitt, Antoine; Torrent, Marc

2015-02-01

106

Prolate spheroidal wave functions induce Gaussian chip waveforms  

Microsoft Academic Search

Slepianpsilas prolate spheroidal wave function (PSWF) is optimum in energy concentration within given frequency bandwidth and time-width. However it is not employed in communications mainly because its inter-symbol interference is unfavorable. We show that introducing Markovian spreading codes makes PSWF be a strong candidate for the chip waveform in CDMA systems. For design tractability, Gaussian waveform is recommended.

Yutaka Jitsumatsu; Tohru Kohda

2008-01-01

107

Unidimensional and bidimensional prolate spheroidal wave functions and applications  

Microsoft Academic Search

In this work, we give a brief description of the theory and the properties of the 1-D and 2-D prolate spheroidal wave functions (PSWFs). Then, we study some efficient methods for the computation of the different PSWFs and their associated eigenvalues. More precisely, we shall develop a quadrature method for the approximation of the 1-D PSWFs. Then, we extend this

Abderrazek Karoui

108

Robust generalized inner products algorithm using prolate spheroidal wave functions  

Microsoft Academic Search

The estimated covariance matrix is corrupted by the interference-target signals (outliers) in nonhomogeneous clutter environments, which leads the conventional space-time adaptive processing (STAP) to be degraded significantly in clutter suppression. Therefore, a robust generalized inner products (GIP) algorithm by utilizing prolate spheroidal wave functions (PSWF) is proposed to eliminate the outliers from the training samples set in this paper. In

Xiaopeng Yang; Yongxu Liu; Xiaona Hu; Teng Long

2012-01-01

109

Analysis of spectral approximations using prolate spheroidal wave functions  

NASA Astrophysics Data System (ADS)

In this paper, the approximation properties of the prolate spheroidal wave functions of order zero (PSWFs) are studied, and a set of optimal error estimates are derived for the PSWF approximation of non-periodic functions in Sobolev spaces. These results serve as an indispensable tool for the analysis of PSWF spectral methods. A PSWF spectral-Galerkin method is proposed and analyzed for elliptic-type equations. Illustrative numerical results consistent with the theoretical analysis are also presented.

Wang, Li-Lian

2010-04-01

110

Uncertainty Principles, Prolate Spheroidal Wave Functions, and Applications  

Microsoft Academic Search

\\u000a In the literature, the prolate spheroidal wave functions (PSWFs) are often regarded as mysterious set of functions of L\\u000a 2(?), with no explicit or standard representation and too difficult to compute numerically. Nonetheless, the PSWFs exhibit the\\u000a unique properties to form an orthogonal basis of L\\u000a 2([ ? 1, 1]), an orthonormal system of L\\u000a 2(R) and an orthonormal basis

Abderrazek Karoui

111

Elastic response of floating glacier ice to impact of longperiod ocean waves  

E-print Network

Elastic response of floating glacier ice to impact of longperiod ocean waves O. V. Sergienko1 given rise to the question of whether mechanical coupling with waves in the ocean may provide general question: how ocean waves affect the stress regime of floating ice, and in particular, how ocean

Rodgers, Keith

112

Impact of the wave number estimation in Underground Focusing SAR images  

Microsoft Academic Search

This work studies the impact estimating soil wave number in Underground Focusing SAR imaging for tunnel detection applications. It is demonstrated that poor underground imaging results when wave refraction at the ground surface is neglected, but that incorporating refraction with sufficiently high estimates of soil dielectric constant produce clear target images. Using a wrong wave number for the soil incorrectly

Fernando Quivira; Jose Angel Martinez Lorenzo; Carey M. Rappaport

2010-01-01

113

Simulation of wind wave growth with reference source functions  

NASA Astrophysics Data System (ADS)

We present results of extensive simulations of wind wave growth with the so-called reference source function in the right-hand side of the Hasselmann equation written as follows First, we use Webb's algorithm [8] for calculating the exact nonlinear transfer function Snl. Second, we consider a family of wind input functions in accordance with recent consideration [9] ( )s S = ?(k)N , ?(k) = ? ? ?- f (?). in k 0 ?0 in (2) Function fin(?) describes dependence on angle ?. Parameters in (2) are tunable and determine magnitude (parameters ?0, ?0) and wave growth rate s [9]. Exponent s plays a key role in this study being responsible for reference scenarios of wave growth: s = 4-3 gives linear growth of wave momentum, s = 2 - linear growth of wave energy and s = 8-3 - constant rate of wave action growth. Note, the values are close to ones of conventional parameterizations of wave growth rates (e.g. s = 1 for [7] and s = 2 for [5]). Dissipation function Sdiss is chosen as one providing the Phillips spectrum E(?) ~ ?5 at high frequency range [3] (parameter ?diss fixes a dissipation scale of wind waves) Sdiss = Cdiss?4w?N (k)?(? - ?diss) (3) Here frequency-dependent wave steepness ?2w = E(?,?)?5-g2 makes this function to be heavily nonlinear and provides a remarkable property of stationary solutions at high frequencies: the dissipation coefficient Cdiss should keep certain value to provide the observed power-law tails close to the Phillips spectrum E(?) ~ ?-5. Our recent estimates [3] give Cdiss ? 2.0. The Hasselmann equation (1) with the new functions Sin, Sdiss (2,3) has a family of self-similar solutions of the same form as previously studied models [1,3,9] and proposes a solid basis for further theoretical and numerical study of wave evolution under action of all the physical mechanisms: wind input, wave dissipation and nonlinear transfer. Simulations of duration- and fetch-limited wind wave growth have been carried out within the above model setup to check its conformity with theoretical predictions, previous simulations [2,6,9], experimental parameterizations of wave spectra [1,4] and to specify tunable parameters of terms (2,3). These simulations showed realistic spatio-temporal scales of wave evolution and spectral shaping close to conventional parameterizations [e.g. 4]. An additional important feature of the numerical solutions is a saturation of frequency-dependent wave steepness ?w in short-frequency range. The work was supported by the Russian government contract No.11.934.31.0035, Russian Foundation for Basic Research grant 11-05-01114-a and ONR grant N00014-10-1-0991. References [1] S. I. Badulin, A. V. Babanin, D. Resio, and V. Zakharov. Weakly turbulent laws of wind-wave growth. J. Fluid Mech., 591:339-378, 2007. [2] S. I. Badulin, A. N. Pushkarev, D. Resio, and V. E. Zakharov. Self-similarity of wind-driven seas. Nonl. Proc. Geophys., 12:891-946, 2005. [3] S. I. Badulin and V. E. Zakharov. New dissipation function for weakly turbulent wind-driven seas. ArXiv e-prints, (1212.0963), December 2012. [4] M. A. Donelan, J. Hamilton, and W. H. Hui. Directional spectra of wind-generated waves. Phil. Trans. Roy. Soc. Lond. A, 315:509-562, 1985. [5] M. A. Donelan and W. J. Pierson-jr. Radar scattering and equilibrium ranges in wind-generated waves with application to scatterometry. J. Geophys. Res., 92(C5):4971-5029, 1987. [6] E. Gagnaire-Renou, M. Benoit, and S. I. Badulin. On weakly turbulent scaling of wind sea in simulations of fetch-limited growth. J. Fluid Mech., 669:178-213, 2011. [7] R. L. Snyder, F. W. Dobson, J. A. Elliot, and R. B. Long. Array measurements of atmospheric pressure fluctuations above surface gravity waves. J. Fluid Mech., 102:1-59, 1981. [8] D. J. Webb. Non-linear transfers between sea waves. Deep Sea Res., 25:279-298, 1978. [9] V. E. Zakharov, D. Resio, and A. N. Pushkarev. New wind input term consistent with experimental, theoretical and numerical considerations. ArXiv e-prints, (1212.1069), December 2012.

Badulin, Sergei I.; Zakharov, Vladimir E.; Pushkarev, Andrei N.

2013-04-01

114

Hertzian impact: experimental study of the force pulse and resulting stress waves.  

PubMed

Ball impact has long been used as a repeatable source of stress waves in solids. The amplitude and frequency content of the waves are a function of the force-time history, or force pulse, that the ball imposes on the massive body. In this study, Glaser-type conical piezoelectric sensors are used to measure vibrations induced by a ball colliding with a massive plate. These measurements are compared with theoretical estimates derived from a marriage of Hertz theory and elastic wave propagation. The match between experiment and theory is so close that it not only facilitates the absolute calibration the sensors but it also allows the limits of Hertz theory to be probed. Glass, ruby and hardened steel balls 0.4 to 2.5 mm in diameter were dropped onto steel, glass, aluminum, and polymethylmethacrylate plates at a wide range of approach velocities, delivering frequencies up to 1.5 MHz into these materials. Effects of surface properties and yielding of the plate material were analyzed via the resulting stress waves and simultaneous measurements of the ball's coefficient of restitution. The sensors are sensitive to surface normal displacements down to about +/-1 pm in the frequency range of 20 kHz to over 1 MHz. PMID:20815445

McLaskey, Gregory C; Glaser, Steven D

2010-09-01

115

Theory of steady-state plane tunneling-assisted impact ionization waves  

SciTech Connect

The effect of band-to-band and trap-assisted tunneling on the properties of steady-state plane ionization waves in p{sup +}-n-n{sup +} structures is theoretically analyzed. It is shown that such tunneling-assisted impact ionization waves do not differ in a qualitative sense from ordinary impact ionization waves propagating due to the avalanche multiplication of uniformly distributed seed electrons and holes. The quantitative differences of tunneling-assisted impact ionization waves from impact ionization waves are reduced to a slightly different relation between the wave velocity u and the maximum field strength E{sub M} at the front. It is shown that disregarding impact ionization does not exclude the possibility of the existence of tunneling-assisted ionization waves; however, their structure radically changes, and their velocity strongly decreases for the same E{sub M}. A comparison of the dependences u(E{sub M}) for various ionization-wave types makes it possible to determine the conditions under which one of them is dominant. In conclusion, unresolved problems concerning the theory of tunneling-assisted impact ionization waves are discussed and the directions of further studies are outlined.

Kyuregyan, A. S., E-mail: ask@vei.ru [Lenin All-Russian Electrical-Engineering Institute (Russian Federation)

2013-07-15

116

Crustal structure of North Dakota from joint inversion of surface wave dispersion and teleseismic P-wave reciever functions  

NASA Astrophysics Data System (ADS)

Studying and determining crustal structure of the Earth is important for understanding the interior of the Earth. Using methods like receiver functions and surface wave dispersion allows the determination of differences in structure and composition through the crust. Jointly inverting receiver functions and surface wave dispersion reduces the error and over-interpretation of the crustal structure estimation. Receiver functions and surface wave dispersion invert well together because receiver functions are very sensitive to velocity contrasts and vertical travel times, and surface wave dispersion is sensitive to average velocity and insensitive to sharp velocity contrasts. By jointly inverting receiver functions and surface wave dispersion, shear wave velocity profiles can be created to determine the properties of the crustal structure and velocity contrasts. With the use of IRIS Transportable Array stations data throughout the United States, this thesis takes a closer look at the crustal structure of North Dakota through the joint inversion of surface wave dispersion and teleseismic P-wave receiver functions. The receiver functions in North Dakota show shallow sediment effects that affect the joint inversion process. In western North Dakota the Williston basin and in eastern North Dakota the Red River Valley cause ringing effects in the receiver functions. The shallow sediments in North Dakota control and overpower the rest of the crustal signal in the receiver functions, and thus affect the ability of determining the crustal shear wave velocity structure of North Dakota through the joint inversion of receiver functions and surface wave dispersion, thus the use of background geology is necessary.

Walsh, Braden Michael

117

Improved wave functions for Hubbard model: Superconductivity and Mott transition  

NASA Astrophysics Data System (ADS)

We extend the doublon-holon binding wave function, which was recently often used to consider Mott transitions and d-wave superconductivity, for the half-filled-band Hubbard model on square lattices with the diagonal hopping t?. We introduce two new features: (1) In the doublon-holon binding factor, more accurate configuration correlations are included. (2) The band renormalization effect owing to the electron correlation is introduced within the third-neighbor hopping, including the anisotropy between x- and y-directions in the nearest-neighbor hopping. Using an optimization variational Monte Carlo technique, we draw some definite answers to the topics concerning the above features.

Kobayashi, Kenji; Yokoyama, Hisatoshi

2007-10-01

118

Wave Function Orthogonality in Relativistic Nucleon Knockout Reactions  

NASA Astrophysics Data System (ADS)

Nucleon knockout reactions such as (e,e'N) and (?,N) are usually treated using the Distorted Wave Impulse Approximation (DWIA). The standard DWIA amplitude suffers from an orthogonality defect which results from the use of nucleon continuum and bound state wave functions that belong to different Hamiltonians. In the past this problem has been discussed mainly within the framework of a nonrelativistic calculation of the amplitude. In the present work, we study the effect of nonorthogonality in the relativistic treatment of the above reactions. The continuum nucleon wave function is made orthogonal to the relevant bound states using the Gram-Schmidt procedure.The orthogonality effects are found to be negligible for (e,e'p) reactions for missing momenta up to 700 MeV/c,for all the three standard coplanar kinematics. By contrast the orthogonalization of the wave functions appears to have a more pronounced effect in the case of (?,p) reactions, particularly at large angles. For these reactions, the spin dependent observables show more sensitivity than the cross sections.

Sherif, H. S.; Johansson, J. I.

1999-10-01

119

Impact Assessment Summary 1. Name of policy, function or service.  

E-print Network

Impact Assessment Summary 1. Name of policy, function or service. Retirement Policy and Procedure 2. Additionally, information from a range of external sources has been obtained. 5. Summary of Impact. The revision of the FC's Retirement Policy & Procedure has a positive impact from an equalities perspective

120

Equality Impact Assessment Summary Name of policy, function or service  

E-print Network

Equality Impact Assessment Summary Name of policy, function or service Water and Soils and Welsh of this can be accessed here: Woodlands for Wales - WAG Equality Impact Assessment. A summary of how E to show that any specific E&D group will be disadvantaged. Forestry Commission Equality Impact Assessment

121

Equality Impact Assessment Summary Name of policy, function or service  

E-print Network

Equality Impact Assessment Summary Name of policy, function or service Heritage, Landscape of woodlands and trees. Forestry Commission Equality Impact Assessment #12;Information and Data (evidence) used here: Woodlands for Wales - WAG Equality Impact Assessment. A summary of how E&D evidence is reflected

122

Quantum Canonical Tensor Model and AN Exact Wave Function  

NASA Astrophysics Data System (ADS)

Tensor models in various forms are being studied as models of quantum gravity. Among them the canonical tensor model has a canonical pair of rank-three tensors as dynamical variables, and is a pure constraint system with first-class constraints. The Poisson algebra of the first-class constraints has structure functions, and provides an algebraically consistent way of discretizing the Dirac first-class constraint algebra for general relativity. This paper successfully formulates the Wheeler-DeWitt scheme of quantization of the canonical tensor model; the ordering of operators in the constraints is determined without ambiguity by imposing Hermiticity and covariance on the constraints, and the commutation algebra of constraints takes essentially the same form as the classical Poisson algebra, i.e. is first-class. Thus one could consistently obtain, at least locally in the configuration space, wave functions of "universe" by solving the partial differential equations representing the constraints, i.e. the Wheeler-DeWitt equations for the quantum canonical tensor model. The unique wave function for the simplest nontrivial case is exactly and globally obtained. Although this case is far from being realistic, the wave function has a few physically interesting features; it shows that locality is favored, and that there exists a locus of configurations with features of beginning of universe.

Sasakura, Naoki

2013-08-01

123

Deducing spectroscopic factors from wave-function asymptotics  

E-print Network

In a coupled-channel model, we explore the effects of coupling between configurations on the radial behavior of the wave function and, in particular, on the spectroscopic factor (SF) and the asymptotic normalization coefficient (ANC). We evaluate the extraction of a SF from the ratio of the ANC of the coupled-channel model to that of a single-particle approximation of the wave function. We perform this study within a core + n collective model, which includes two states of the core that connect by a rotational coupling. To get additional insights, we also use a simplified model that takes a delta function for the coupling potential. Calculations are performed for 11Be. Fair agreement is obtained between the SF inferred from the single-particle approximation and the one obtained within the coupled-channel models. Significant discrepancies are observed only for large coupling strength and/or large admixture, that is, a small SF. This suggests that reliable SFs can be deduced from the wave-function asymptotics when the structure is dominated by one configuration, that is, for a large SF.

P. Capel; P. Danielewicz; F. M. Nunes

2010-12-08

124

Boundary conditions on internal three-body wave functions Kevin A. Mitchell and Robert G. Littlejohn  

E-print Network

Boundary conditions on internal three-body wave functions Kevin A. Mitchell and Robert G and m quantum numbers may be expressed in terms of an internal wave function k l , which is a function and where k l , the ``internal wave func- tion,'' is a function of three internal or shape coordinates

Mitchell, Kevin A.

125

IMPACTS OF URBANIZATION ON WATERSHED HYDROLOGIC FUNCTION  

EPA Science Inventory

Although urbanization has a major impact on watershed hydrology, there have not been studies to quantify basic hydrological relationships that are altered by the addition of impervious surfaces. The USDA-ARS and USEPA-ORD-NRMRL have initiated a pilot program to study the impacts...

126

Exact wave functions for atomic electron interacting with photon fields  

NASA Astrophysics Data System (ADS)

Many nonlinear quantum optical physics phenomena need more accurate wave functions and corresponding energy or quasienergy levels to account for. An analytic expression of wave functions with corresponding energy levels for an atomic electron interacting with a photon field is presented as an exact solution to the Schrödinger-like equation involved with both atomic Coulomb interaction and electron-photon interaction. The solution is a natural generalization of the quantum-field Volkov states for an otherwise free electron interacting with a photon field. The solution shows that an Nlevel atom in light form stationary states without extra energy splitting in addition to the Floquet mechanism. The treatment developed here with computing codes can be conveniently transferred to quantum optics in classical-field version as research tools to benefit the whole physics community.

Guo, Dong-Sheng

2013-02-01

127

Wave function engineering in quantum dot-ring nanostructures  

NASA Astrophysics Data System (ADS)

Modern nanotechnology allows the production of, depending on the application, various quantum nanostructures with selected properties. These properties are strongly influenced by the confinement potential which can be modified e.g. by electrical gating. In this paper, we analyze a nanostructure composed of a quantum dot surrounded by a quantum ring. We show that, depending on the details of the confining potential, the electron wave functions can be located in different parts of the structure. Since many properties of such a nanostructure strongly depend on the distribution of the wave functions, by varying the applied gate voltage one can easily control them. In particular, we illustrate the high controllability of the nanostructure by demonstrating how its coherent, optical and conducting properties can be drastically changed by a small modification of the confining potential.

Zipper, El?bieta; Kurpas, Marcin; Ma?ka, Maciej M.

2012-09-01

128

Singlet Mott state simulating the bosonic Laughlin wave function  

NASA Astrophysics Data System (ADS)

We study properties of a class of spin-singlet Mott states for arbitrary spin S bosons on a lattice, with particle number per cite n =S/l+1, where l is a positive integer. We show that such a singlet Mott state can be mapped to a bosonic Laughlin wave function on a sphere with a finite number of particles at filling ? =1/2l. Spin, particle, and hole excitations in the Mott state are discussed, among which the hole excitation can be mapped to the quasihole of the bosonic Laughlin wave function. We show that this singlet Mott state can be realized in a cold-atom system on an optical lattice and can be identified using Bragg spectroscopy and Stern-Gerlach techniques. This class of singlet Mott states may be generalized to map to bosonic Laughlin states with filling ? =q/2l.

Lian, Biao; Zhang, Shoucheng

2014-01-01

129

Laughlin wave function and one-dimensional free fermions  

SciTech Connect

Making use of the well-known phase-space reduction in the lowest Landau level, we show that the Laughlin wave function for the {nu}=1/{ital m} case can be obtained exactly as a coherent-state representation of a one-dimensional (1D) wave function. The 1D system consists of {ital m} copies of free fermions associated with each of the {ital N} electrons, confined in a common harmonic well potential. Interestingly, the condition for this exact correspondence is found to incorporate Jain`s parton picture. We argue that this correspondence between the free fermions and quantum Hall effect is due to the mapping of the 1D system under consideration to the Gaussian unitary ensemble in the random matrix theory.

Panigrahi, P.K.; Sivakumar, M. [School of Physics, University of Hyderabad, Hyderabad-500 134 (India)] [School of Physics, University of Hyderabad, Hyderabad-500 134 (India)

1995-11-15

130

Impact damage detection in sandwich composite structures using Lamb waves and laser vibrometry  

NASA Astrophysics Data System (ADS)

This experimental study explores the feasibility of impact damage detection in composite sandwich structures using Lamb wave excitation and signals acquired with a laser Doppler vibrometer. Energy maps are computed from the transient velocity wave fields and used to highlight defect areas in impacted coupons of foam core and honeycomb core sandwich materials. The technique performs well for the detection of barely visible damage in this type of material, and is shown to be robust in the presence of wave reverberation. Defect extent information is not always readily retrieved from the obtained defect signatures, which depend on the wave - defect interaction mechanisms.

Lamboul, B.; Passilly, B.; Roche, J.-M.; Osmont, D.

2013-01-01

131

Wave characteristics in functionally graded piezoelectric hollow cylinders  

Microsoft Academic Search

Based on linear three-dimensional piezoelasticity, the Legendre orthogonal polynomial series expansion approach is used for\\u000a determining the wave characteristics in hollow cylinders composed of the functionally graded piezoelectric materials (FGPM)\\u000a with open circuit. The displacement and electric potential components, expanded in a series of Legendre polynomials, are introduced\\u000a into the governing equations along with position-dependent material constants so that the

Yu Jiangong; Wu Bin; Chen Guoqiang

2009-01-01

132

Two dimensional prolate spheroidal wave functions for MRI  

Microsoft Academic Search

The tradeoff between spatial and temporal resolution is often used to increase data acquisition speed for dynamic MR imaging. Reduction of the k-space sampling area, however, leads to stronger partial volume and truncation effects. A two dimensional prolate spheroidal wave function (2D-PSWF) method is developed to address these problems. Utilizing prior knowledge of a given region of interest (ROI) and

Qing X. Yang; Martin A Lindquist; Lawrence Shepp; Cun-Hui Zhang; Jianli Wang; Michael B Smith

2002-01-01

133

Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches.  

PubMed

The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H2O)(-), Gd(III)DTPA(H2O)(2-), and Gd(III)(H2O)8 (3+) in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude. PMID:25612706

Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael

2015-01-21

134

Systematic theoretical investigation of the zero-field splitting in Gd(III) complexes: Wave function and density functional approaches  

NASA Astrophysics Data System (ADS)

The zero-field splitting (ZFS) of the electronic ground state in paramagnetic ions is a sensitive probe of the variations in the electronic and molecular structure with an impact on fields ranging from fundamental physical chemistry to medical applications. A detailed analysis of the ZFS in a series of symmetric Gd(III) complexes is presented in order to establish the applicability and accuracy of computational methods using multiconfigurational complete-active-space self-consistent field wave functions and of density functional theory calculations. The various computational schemes are then applied to larger complexes Gd(III)DOTA(H2O)-, Gd(III)DTPA(H2O)2-, and Gd(III)(H2O)83+ in order to analyze how the theoretical results compare to experimentally derived parameters. In contrast to approximations based on density functional theory, the multiconfigurational methods produce results for the ZFS of Gd(III) complexes on the correct order of magnitude.

Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael

2015-01-01

135

Energy optimization of quantum Monte Carlo wave functions  

NASA Astrophysics Data System (ADS)

In recent years many methods have been proposed for energy optimizing quantum Monte Carlo wave functions. Of these, the three highly efficient methods are: 1) The generalized eigenvalue method of Nightingale and Melik-Alaverdian, which was proposed by them for linear parameters only but extended by us to nonlinear parameters. 2) The effective fluctuation potential (EFP) method of Fahy, Filippi and coworkers, and the recent perturbative EFP of Schautz, Scemama and Filippi. We show that the latter can be more simply derived as first-order perturbation theory in a nonorthogonal basis. 3) The modified Newton method of Umrigar and Filippi and of Sorella. We show that the three methods are related to each other and point out that a control parameter can be employed in each of them to make them totally stable. We use these methods to optimize all the parameters in the Jastrow and the determinantal parts of the wave function and point out that different issues arise in optimizing the Jastrow and the determinantal parameters. By systematically increasing the number of determinants we find that seemingly similar systems, such as C2 and Si2 have vastly different fixed-node errors for single-determinant wave functions.

Umrigar, C. J.; Toulouse, J.

2006-03-01

136

Coupling of WRF meteorological model to WAM spectral wave model through sea surface roughness at the Balearic Sea: impact on wind and wave forecasts  

NASA Astrophysics Data System (ADS)

Meteorological models, like WRF, usually describe the earth surface characteristics by tables that are function of land-use. The roughness length (z0) is an example of such approach. However, over sea z0 is modeled by the Charnock (1955) relation, linking the surface friction velocity u*2 with the roughness length z0 of turbulent air flow, z0 = ?-u2* g The Charnock coefficient ? may be considered a measure of roughness. For the sea surface, WRF considers a constant roughness ? = 0.0185. However, there is evidence that sea surface roughness should depend on wave energy (Donelan, 1982). Spectral wave models like WAM, model the evolution and propagation of wave energy as a function of wind, and include a richer sea surface roughness description. Coupling WRF and WAM is thus a common way to improve the sea surface roughness description of WRF. WAM is a third generation wave model, solving the equation of advection of wave energy subject to input/output terms of: wind growth, energy dissipation and resonant non-linear wave-wave interactions. Third generation models work on the spectral domain. WAM considers the Charnock coefficient ? a complex yet known function of the total wind input term, which depends on the wind velocity and on the Charnock coefficient again. This is solved iteratively (Janssen et al., 1990). Coupling of meteorological and wave models through a common Charnock coefficient is operationally done in medium-range met forecasting systems (e.g., at ECMWF) though the impact of coupling for smaller domains is not yet clearly assessed (Warner et al, 2010). It is unclear to which extent the additional effort of coupling improves the local wind and wave fields, in comparison to the effects of other factors, like e.g. a better bathymetry and relief resolution, or a better circulation information which might have its influence on local-scale meteorological processes (local wind jets, local convection, daily marine wind regimes, etc.). This work, within the scope of the 7th EU FP Project FIELD_AC, assesses the impact of coupling WAM and WRF on wind and wave forecasts on the Balearic Sea, and compares it with other possible improvements, like using available high-resolution circulation information from MyOcean GMES core services, or assimilating altimeter data on the Western Mediterranean. This is done in an ordered fashion following statistical design rules, which allows to extract main effects of each of the factors considered (coupling, better circulation information, data assimilation following Lionello et al., 1992) as well as two-factor interactions. Moreover, the statistical significance of these improvements can be tested in the future, though this requires maximum likelihood ratio tests with correlated data. Charnock, H. (1955) Wind stress on a water surface. Quart.J. Row. Met. Soc. 81: 639-640 Donelan, M. (1982) The dependence of aerodynamic drag coefficient on wave parameters. Proc. 1st Int. Conf. on Meteorology and Air-Sea Interactions of teh Coastal Zone. The Hague (Netherlands). AMS. 381-387 Janssen, P.A.E.M., Doyle, J., Bidlot, J., Hansen, B., Isaksen, L. and Viterbo, P. (1990) The impact of oean waves on the atmosphere. Seminars of the ECMWF. Lionello, P., Günther, H., and Janssen P.A.E.M. (1992) Assimilation of altimeter data in a global third-generation wave model. Journal of Geophysical Research 97 (C9): 453-474. Warner, J., Armstrong, B., He, R. and Zambon, J.B. (2010) Development of a Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System. Ocean Modelling 35: 230-244.

Tolosana-Delgado, R.; Soret, A.; Jorba, O.; Baldasano, J. M.; Sánchez-Arcilla, A.

2012-04-01

137

Born-Oppenheimer wave function near level crossing  

NASA Astrophysics Data System (ADS)

The standard Born-Oppenheimer theory does not give an accurate description of the wave function near points of level crossing. We give such a description near an isotropic conic crossing, for energies close to the crossing energy. This leads to the study of two coupled second-order ordinary differential equations whose solution is described in terms of the generalized hypergeometric functions of the kind 0F3(;a,b,c;z). We find that, at low angular momenta, the mixing due to crossing is surprisingly large, scaling like ?1/6, where ? is the electron to nuclear mass ratio.

Avron, J. E.; Gordon, A.

2000-12-01

138

Wave function for harmonically confined electrons in time-dependent electric and magnetostatic fields  

SciTech Connect

We derive via the interaction “representation” the many-body wave function for harmonically confined electrons in the presence of a magnetostatic field and perturbed by a spatially homogeneous time-dependent electric field—the Generalized Kohn Theorem (GKT) wave function. In the absence of the harmonic confinement – the uniform electron gas – the GKT wave function reduces to the Kohn Theorem wave function. Without the magnetostatic field, the GKT wave function is the Harmonic Potential Theorem wave function. We further prove the validity of the connection between the GKT wave function derived and the system in an accelerated frame of reference. Finally, we provide examples of the application of the GKT wave function.

Zhu, Hong-Ming; Chen, Jin-Wang; Pan, Xiao-Yin, E-mail: panxiaoyin@nbu.edu.cn [Department of Physics, Ningbo University, Ningbo 315211 (China)] [Department of Physics, Ningbo University, Ningbo 315211 (China); Sahni, Viraht [Department of Physics, Brooklyn College and The Graduate School of the City University of New York, New York, New York 10016 (United States)] [Department of Physics, Brooklyn College and The Graduate School of the City University of New York, New York, New York 10016 (United States)

2014-01-14

139

Wave function for harmonically confined electrons in time-dependent electric and magnetostatic fields  

NASA Astrophysics Data System (ADS)

We derive via the interaction "representation" the many-body wave function for harmonically confined electrons in the presence of a magnetostatic field and perturbed by a spatially homogeneous time-dependent electric field—the Generalized Kohn Theorem (GKT) wave function. In the absence of the harmonic confinement - the uniform electron gas - the GKT wave function reduces to the Kohn Theorem wave function. Without the magnetostatic field, the GKT wave function is the Harmonic Potential Theorem wave function. We further prove the validity of the connection between the GKT wave function derived and the system in an accelerated frame of reference. Finally, we provide examples of the application of the GKT wave function.

Zhu, Hong-Ming; Chen, Jin-Wang; Pan, Xiao-Yin; Sahni, Viraht

2014-01-01

140

Computational aspects of the continuum quaternionic wave functions for hydrogen  

NASA Astrophysics Data System (ADS)

Over the past few years considerable attention has been given to the role played by the Hydrogen Continuum Wave Functions (HCWFs) in quantum theory. The HCWFs arise via the method of separation of variables for the time-independent Schrödinger equation in spherical coordinates. The HCWFs are composed of products of a radial part involving associated Laguerre polynomials multiplied by exponential factors and an angular part that is the spherical harmonics. In the present paper we introduce the continuum wave functions for hydrogen within quaternionic analysis ((R)QHCWFs), a result which is not available in the existing literature. In particular, the underlying functions are of three real variables and take on either values in the reduced and full quaternions (identified, respectively, with R3 and R4). We prove that the (R)QHCWFs are orthonormal to one another. The representation of these functions in terms of the HCWFs are explicitly given, from which several recurrence formulae for fast computer implementations can be derived. A summary of fundamental properties and further computation of the hydrogen-like atom transforms of the (R)QHCWFs are also discussed. We address all the above and explore some basic facts of the arising quaternionic function theory. As an application, we provide the reader with plot simulations that demonstrate the effectiveness of our approach. (R)QHCWFs are new in the literature and have some consequences that are now under investigation.

Morais, J.

2014-10-01

141

Interaction of waves, currents and tides, and wave-energy impact on the beach area of Sylt Island  

NASA Astrophysics Data System (ADS)

Erosion due to waves is an important and actual problem for most coastal areas of the North Sea. The objective of this study was to estimate the impact of wave action on the coastline of Sylt Island. From a 2-year time series (November 1999 to October 2001) of hydrological and wave parameters generated with a coupled wave-current modelling system, a period comprising storm ‘Anatol’ (3-4 December 1999) is used to investigate the effects of waves on currents and water levels and the input of wave energy into the coastline. The wave-induced stress causes an increase of the current velocity of 1 m/s over sand and an additional drift along the coast of about 20 cm/s. This produces a water level increase of more than 20 cm in parts of the tidal basin. The model system also calculates the wave energy input into the coastline. Scenario runs for December 1999 with a water level increase of 50 cm and wind velocity increased by 10% show that the input of the wave energy into the west coast of Sylt Island increases by 30% compared to present conditions. With regard to the forecasted near-future (Woth et al., Ocean Dyn 56:3-15, 2006) increase of strong storm surges, the scenario results indicate an increased risk of coastal erosion in the surf zone of Sylt Island.

Pleskachevsky, Andrey; Eppel, Dieter P.; Kapitza, Hartmut

2009-06-01

142

S-wave velocity structure in southwest China from surface wave tomography and receiver functions  

NASA Astrophysics Data System (ADS)

Using the surface wave records of 504 teleseismic events at 50 temporal and 92 permanent seismic stations in southwest China, we extracted the phase velocity dispersion curves with interstation correlation method, and obtained the phase velocity maps at 10, 15, 25, 40, 60 and 75 s with a grid space of 0.5×0.5 from surface wave tomography. Meanwhile, we obtained the S-wave velocity structures beneath three profiles from the joint inversion of receiver functions and surface waves. From the maps at short periods (10 and 15 s) and long periods (40, 60 and 75 s), different distribution features of high velocity zones (HVZs for short) and low velocity zones (LVZs for short) are shown in the study area: HVZs at short periods are shown in the Panzhihua - Emeishan region, Sichuan basin and Weixi-Lijiang region, surrounding the LVZs from Songpan-Ganzi block to the east of Lijiang where there are significant higher elevations; whereas HVZs at long periods are shown in the Weixi-Lijiang region, Panzhihua-Chuxiong basin and Kunming-Tonghai region and forming a line in the center part of the study area, and the fast polarization directions of the shear wave from SKS analysis on the two sides of the line change significantly. These phenomena indicate plateau material flow can be blocked in two different depth intervals and leads to different horizontal extensions. From the maps at long periods and the structures along the profiles, LVZs are shown in the upper mantle beneath rapid slip fault zones, such as Anninghe - Zemuhe - Xiaojiang fault zone, Red River fault zone and Xiaojinhe fault zone, implying these faults are deep penetrating faults. Figure (a-f) Rayleigh wave phase velocity maps at 10, 15, 25,40,60 and 75 s with a resolution of 100 km. The black lines represent faults. The red points represent M?6 earthquakes. The colour scale changes in different panels. Figure (g) Distribution of the seismic stations and regional tectonic features in the study area. Figure (h-j) The S wave velocity structures beneath the profiles AA', BB' and CC' from the joint inversion of receiver functions and surface waves. The results at different stations are vertically projected to the profiles.

Wang, W.; Wu, J.; Fang, L.; Lai, G.; Yang, T.

2013-12-01

143

Sedimentological effects of tsunamis, with particular reference to impact-generated and volcanogenic waves  

Microsoft Academic Search

Impulse-generated waves (tsunamis) may be produced, at varying scales and global recurrence intervals (RI), by several processes. Meteorite-water impacts will produce tsunamis, and asteroid-scale impacts with associated mega-tsunamis may occur. A bolide-water impact would undoubtedly produce a major tsunami, whose sedimentological effects should be recognizable. Even a bolide-land impact might trigger major submarine landslides and thus tsunamis. In all posulated

Joanne Bourgeois; Patricia L. Wiberg

1988-01-01

144

Multicenter distorted-wave method for fast-electron-impact single ionization of molecules  

NASA Astrophysics Data System (ADS)

A multicenter distorted-wave (MCDW) method for fast-electron-impact single ionization of a molecular system in the coplanar-asymmetric kinematics is developed. Plane waves are used to describe the fast incoming and outgoing electrons and the multicenter nature of the molecule is considered by describing the slow ejected electron with the multicenter distorted wave, which is solved from the anisotropic multicenter potential between the ejected electron and the ionic molecule. The MCDW method improves the conventional molecular distorted-wave methods, whose distorted wave is solved from the spherically averaged isotropic potential. The application to the water molecule shows reasonable agreement with the available experimental data.

Zhang, Song bin; Li, Xing Yu; Wang, Jian Guo; Qu, Yi Zhi; Chen, Xiangjun

2014-05-01

145

Unification of dark matter and dark energy via quantum wave function collapse  

Microsoft Academic Search

Dynamical wave function collapse models entail the continuous liberation of a specified rate of energy arising from the interaction of a fluctuating scalar field with the matter wave function. We consider the wave function collapse process for the constituents of dark matter in our universe. Beginning from a particular early era of the universe chosen from physical considerations, the rate

A. S. Majumdar

146

Finite range distorted-wave Born approximation analysis of (p,t) reactions with a realistic triton wave function  

NASA Astrophysics Data System (ADS)

Exact finite range distorted-wave Born approximation analysis of the ground state reactions 208Pb(p,t)206Pb and 18O(p,t)16O are presented. The calculations are carried out using a realistic triton wave function comprising a spatially symmetric S and mixed symmetric S' and D states. The transfer interaction is treated consistently with the interaction used in obtaining the triton wave function. The use of a realistic wave function and transfer potential yields improved agreement between experimental and theoretical angular distributions. Calculations using the wave function of the transferred neutron pair suggest it is possible to explain both the absolute magnitude and shape of the angular distribution for these transitions. NUCLEAR REACTIONS (p,t), distorted-wave Born approximation analyses.

Werby, M. F.; Strayer, M. R.; Nagarajan, M. A.

1980-06-01

147

Impact of Stone Removal on Renal Function: A Review  

PubMed Central

Stone removal can improve renal function by eradicating obstruction and, in certain cases, an underlying infection. Stone-removing procedures, however, may negatively impact functional integrity. Many things may impact the latter, including the procedures used, the methods of assessing function, the time when these assessments are made, the occurrence of complications, the baseline condition of the kidney, and patient-related factors. In the majority of cases, little significant functional impairment occurs. However, there are gaps in our knowledge of this subject, including the cumulative effects of multiple procedures violating the renal parenchyma and long-term functional outcomes. PMID:21935339

Wood, Kyle; Keys, Tristan; Mufarrij, Patrick; Assimos, Dean G

2011-01-01

148

On African easterly waves that impacted two tropical cyclones in 2004 Melinda S. Peng,1  

E-print Network

On African easterly waves that impacted two tropical cyclones in 2004 Melinda S. Peng,1 Bing Fu,2 cyclones. Danielle and Earl (2004) formed approximately at the same time in the Atlantic. A three to eight of the African easterly waves related to the two cyclones. The time-filtered 850 mb vorticity shows that African

Li, Tim

149

The stability of freak waves with regard to external impact and perturbation of initial data  

NASA Astrophysics Data System (ADS)

We investigate solutions of the equations, describing freak waves, in perspective of stability with regard to external impact and perturbation of initial data. The modeling of freak waves is based on numerical solution of equations describing a non-stationary potential flow of the ideal fluid with a free surface. We consider the two-dimensional infinitely deep flow. For waves modeling we use the equations in conformal variables. The variant of these equations is offered in [1]. Mathematical correctness of these equations was discussed in [2]. These works establish the uniqueness of solutions, offer the effective numerical solution calculation methods, prove the numerical convergence of these methods. The important aspect of numerical modeling of freak waves is the stability of solutions, describing these waves. In this work we study the questions of stability with regards to external impact and perturbation of initial data. We showed the stability of freak waves numerical model, corresponding to the external impact. We performed series of computational experiments with various freak wave initial data and random external impact. This impact means the power density on free surface. In each experiment examine two waves: the wave that was formed by external impact and without one. In all the experiments we see the stability of equation`s solutions. The random external impact practically does not change the time of freak wave formation and its form. Later our work progresses to the investigation of solution's stability under perturbations of initial data. We take the initial data that provide a freak wave and get the numerical solution. In common we take the numerical solution of equation with perturbation of initial data. The computing experiments showed that the freak waves equations solutions are stable under perturbations of initial data.So we can make a conclusion that freak waves are stable relatively external perturbation and perturbation of initial data both. 1. Zakharov V.E., Dyachenko A.I., Vasilyev O.A. New method for numerical simulation of a nonstationary potential flow of incompressible fluid with a free surface// Eur. J.~Mech. B Fluids. 2002. V. 21. P. 283-291. 2. R.V. Shamin. Dynamics of an Ideal Liquid with a Free Surface in Conformal Variables // Journal of Mathematical Sciences, Vol. 160, No. 5, 2009. P. 537-678. 3. R.V. Shamin, V.E. Zakharov, A.I. Dyachenko. How probability for freak wave formation can be found // THE EUROPEAN PHYSICAL JOURNAL - SPECIAL TOPICS Volume 185, Number 1, 113-124, DOI: 10.1140/epjst/e2010-01242-y

Smirnova, Anna; Shamin, Roman

2014-05-01

150

A Critical Examination of Wind-Wave Spectral Functional Form  

NASA Technical Reports Server (NTRS)

Traditionally, data from random ocean waves are presented in spectral functions. The spectra are the result of Fourier analysis. Fourier spectral analysis has dominated data analysis for, at least, the last hundred years. It has been the standard method for is examining the global amplitude-frequency distributions. Although Fourier transform valid under extremely general conditions, there are some crucial restrictions for the Fourier spectral analysis. The system must be linear, and the data must be stationary- otherwise, the resulting spectrum will make little physical sense. The stationarity requirement is also a common required criterion for most of other available data analysis methods. Nevertheless, few, if any, natural phenomena are linear and stationary. To compound these complications is the imperfection of our probes or numerical schemes the interactions of the imperfect probes even with a perfect linear system can make the final data nonlinear. Furthermore, all the available data are usually of finite duration. Under these conditions, Fourier analysis is of limited use, For lack of alternatives, however, Fourier analysis is still used to process such data. The loose application of Fourier analysis and the insouciant adoption of the stationary and linear assumptions may lead to misleading conclusions. Ocean waves are know to be nonlinear, and the wind system generating the wave field are seldom stationary- As a result, the traditional examination of the spectral form hardly made physical sense. A new method for analyzing nonlinear and nonstationary data has been developed. The key part is the Empirical Mode Decomposition (EMD) method with which any complicated data set can be decomposed into a finite and often small number of Intrinsic Mode Functions (IMF) that serve as the basis of the representation of the data, This decomposition method is adaptive, and, therefore, highly efficient. The IMFs admit well-behaved Hilbert transforms, and yield instantaneous energy and frequency as functions of time that give sharp identifications of imbedded structures. The final presentation of the results is an energy-frequency-time distribution, designated as the Hilbert Spectrum. Among the main conceptual innovations is the introduction of the instantaneous frequencies for complicated data sets, which eliminate the need of spurious harmonics to represent nonlinear and nonstationary signals. The spectral forms of the ocean waves are very different. This new method offers the first physical meaningful view of the wave spectrum. Data from laboratory and field will be presented to illustrate the differences.

Huang, Norden E.; Long, Steven R.

1999-01-01

151

Evolution of the air cavity during a depressurized wave impact. II. The dynamic field  

NASA Astrophysics Data System (ADS)

The present paper on wave-impact events in depressurized environments completes the analysis of Part I by focusing on the dynamical features of the impacts and on the influence of the ambient pressure. Connection is made between the impact regimes typically described in the literature and the stages described in Part I [C. Lugni, M. Miozzi, M. Brocchini, and O. M. Faltinsen, "Evolution of the air cavity during a depressurized wave impact. I. The kinematic flow field," Phys. Fluids 22, 056101 (2010)]. The stages of isotropic/anisotropic compression and expansion of the air cavity are of particular interest. The impact duration at the wall is almost independent of its height above the undisturbed surface level, but its intensity rapidly decreases in the body of the fluid (the peak pressure halves within the first two compression/expansion cycles). The time evolution of the pressure loads on the wall is analyzed by means of the Hilbert transform and an empirical mode decomposition of the signals. This enables identification of the intrinsic mode functions which best fit the original signal during its evolution and quantification of the frequency downshifting which characterize the whole process. The pressure decay, largely governed by air leakage out of the cavity, is found to be very intense during the air cavity closure and the isotropic compression/expansion cycle [stages (1) and (2)]; the decay observed during stage (3), i.e., during the anisotropic compression/expansion cycles, is weaker and independent of the vertical location down the wall. Differences between the observed decay rates and those of a three-dimensional bubble in an infinite fluid are mainly due to the bubble being two-dimensional, being close to the free surface and loosing air. The role of both ullage and vapor pressures on the impact is described, respectively, by means of the Euler and cavitation numbers. The frequency of the bubble oscillation depends on these numbers in a way that is closely similar to that displayed by the bubble area, see Part I.

Lugni, C.; Brocchini, M.; Faltinsen, O. M.

2010-05-01

152

Equality Impact Assessment Summary Name of policy, function or service  

E-print Network

Equality Impact Assessment Summary Name of policy, function or service Health and Well: Woodlands for Wales - WAG Equality Impact Assessment. In addition to the evidence collated in that exercise, new and emerging evidence has been collated from the Equality Issues in Wales: a research review

153

Equality Impact Assessment Summary Name of policy, function or service  

E-print Network

Equality Impact Assessment Summary Name of policy, function or service Education, Learning. The results of this can be accessed here: Woodlands for Wales - WAG Equality Impact Assessment. In addition to the evidence collated in that exercise, new and emerging evidence has been collated from the Equality Issues

154

Classification and Functional Separable Solutions to Extended Nonlinear Wave Equations  

NASA Astrophysics Data System (ADS)

The generalized conditional symmetry approach is applied to study the variable separation of the extended wave equations. Complete classification of those equations admitting functional separable solutions is obtained and exact separable solutions to some of the resulting equations are constructed. The project supported by the National Outstanding Youth Foundation of China under Grant No. 19925522, the Research Fund for the Doctoral Program of Higher Education of China under Grant No. 2000024832, and National Natural Science Foundation of China under Grant Nos. 10447007 and 10475055

Zhang, Shun-Li; Lou, Sen-Yue; Qu, Chang-Zheng; Yue, Rui-Hong

2005-10-01

155

Measurement of stress wave asymmetries in hypervelocity projectile impact experiments  

Microsoft Academic Search

Asymmetries in both structure and ejecta are observed around a number of craters on planetary surfaces. Similar asymmetries have been documented for hypervelocity impact experiments. Such asymmetries arise from the stress front developed around oblique impacts. The onset angle for asymmetric stress distributions indicates that geologic asymmetries should be present in a significant fraction of impact structures.

Jason M. Dahl; Peter H. Schultz

2001-01-01

156

Ocean Wave-Radar Modulation Transfer Functions From the West Coast Experiment  

Microsoft Academic Search

Short gravity-capillary waves, the equilibrium, or the steady state excitations of the ocean surface are modulated by longer ocean waves. These short waves are the predominant microwave scatterers on the ocean surface under many viewing conditions so that the modulation is readily measured with CW Doppler radar used as a two-scale wave probe. Modulation transfer functions (the ratio of the

J. W. Wright; W. J. Plant; W. C. Keller; W. L. Jones

1980-01-01

157

Asymmetry in Directional Spreading Function of Random Waves due to Refraction  

E-print Network

Asymmetry in Directional Spreading Function of Random Waves due to Refraction Changhoon Lee1 ; Jae due to wave refraction. The asymmetry created by refraction increases with the offshore peak wave and is shown to better capture changes in the directional distribution that occur in a refracting, random wave

Haller, Merrick

158

Nonlinear elastic wave spectroscopy identification of impact damage on a sandwich plate  

Microsoft Academic Search

Fragility of composite material to impact loading limits their application in aircraft structures. There is the need to develop reliable monitoring devices capable of localizing and assessing impact damage. At this aim, a new technique, non-linear elastic wave spectroscopy (NEWS), developed for geophysics applications, is investigated and presented in this paper. The NEWS damage detection based technique consists in the

M. Meo; G. Zumpano

2005-01-01

159

The Environmental Impact of a Wave Dragon Array Operating in the Black Sea  

PubMed Central

The present work describes a study related to the influence on the shoreline dynamics of a wave farm consisting of Wave Dragon devices operating in the western side of the Black Sea. Based on historical data analysis of the wave climate, the most relevant environmental conditions that could occur were defined, and for these cases, simulations with SWAN spectral phase averaged wave model were performed. Two situations were considered for the most representative patterns: model simulations without any wave energy converter and simulations considering a wave farm consisting of six Wave Dragon devices. Comparisons of the wave model outputs have been carried out in both geographical and spectral spaces. The results show that although a significant influence appears near the wave farm, this gradually decreases to the coast line level. In order to evaluate the influence of the wave farm on the longshore currents, a nearshore circulation modeling system was used. In relative terms, the longshore current velocities appear to be more sensitive to the presence of the wave farm than the significant wave height. Finally, the possible impact on the marine flora and fauna specific to the target area was also considered and discussed. PMID:23844401

Rusu, Eugen

2013-01-01

160

Phase-space manipulations of many-body wave functions  

NASA Astrophysics Data System (ADS)

We explore the manipulation in phase space of many-body wave functions that exhibit self-similar dynamics under the application of sudden force and/or in the presence of a constant acceleration field. For this purpose, we work out a common theoretical framework based on the Wigner function. We discuss squeezing in position space, phase-space rotation, and its implications in cooling for both noninteracting and interacting gases and time-reversal operation. We discuss various optical analogies and calculate the role of a spherical-like aberration in cooling protocols. We also present the equivalent of a spin-echo technique to improve the robustness of velocity dispersion reduction protocols.

Condon, G.; Fortun, A.; Billy, J.; Guéry-Odelin, D.

2014-12-01

161

Insights Into Caribbean Lithospheric Structure From S Wave Receiver Functions  

NASA Astrophysics Data System (ADS)

BOLIVAR (Broadband Ocean-Land Investigation of Venezuela and the Antilles arc Region) was aimed at investigating the interplay between the lithospheric and asthenospheric mantle of the Caribbean and the South America plates. The oblique collision of the Caribbean plate migrating eastwards has created a complicated deformation zone with strike-slip, compressional and extensional structures along the Caribbean and South America boundary. Earlier results with P receiver functions revealed strong variations in crustal thickness ranging from 15 km beneath the Caribbean Sea to 55 km beneath Venezuela. However, one of the fundamental questions not yet resolved concerns the thickness of the lithosphere in this region. Using the S wave receiver function technique, we analyzed seismograms from some 100 events at epicentral distances of 55-125 degree. The seismograms were rotated and deconvolved to isolate S-to-P conversions from the incident S wave. These were subsequently stacked after their respective conversion points and mapped into the subsurface. A strong negative phase is associated with the S-to-P conversion from the base of the lithosphere. Analysis of these data is ongoing, but we expect to see large variation in lithospheric thickness as the BOLIVAR array spans the transition from the Caribbean with OBS stations to the interior of South America (Guyana Shield).

Landes, M.; Pavlis, G. L.

2007-12-01

162

Configuration interaction wave functions: a seniority number approach.  

PubMed

This work deals with the configuration interaction method when an N-electron Hamiltonian is projected on Slater determinants which are classified according to their seniority number values. We study the spin features of the wave functions and the size of the matrices required to formulate states of any spin symmetry within this treatment. Correlation energies associated with the wave functions arising from the seniority-based configuration interaction procedure are determined for three types of molecular orbital basis: canonical molecular orbitals, natural orbitals, and the orbitals resulting from minimizing the expectation value of the N-electron seniority number operator. The performance of these bases is analyzed by means of numerical results obtained from selected N-electron systems of several spin symmetries. The comparison of the results highlights the efficiency of the molecular orbital basis which minimizes the mean value of the seniority number for a state, yielding energy values closer to those provided by the full configuration interaction procedure. PMID:24952519

Alcoba, Diego R; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Oña, Ofelia B

2014-06-21

163

Impact of Exotic Invertebrate Invaders on Food Web Structure and Function in the Great Lakes: a Network Analysis Approach  

E-print Network

Impact of Exotic Invertebrate Invaders on Food Web Structure and Function in the Great Lakes a second wave of species invasions dominated by exotic invertebrates- Zebra mussels (Dreissena polymorpha invasions (e.g., sea Lamprey and Alewife), these invertebrates inserted themselves in the lower trophic

164

Pineal Function: Impact of Microarray Analysis  

PubMed Central

Microarray analysis has provided a new understanding of pineal function by identifying genes that are highly expressed in this tissue relative to other tissues and also by identifying over 600 genes that are expressed on a 24-hour schedule. This effort has highlighted surprising similarity to the retina and has provided reason to explore new avenues of study including intracellular signaling, signal transduction, transcriptional cascades, thyroid/retinoic acid hormone signaling, metal biology, RNA splicing, and the role the pineal gland plays in the immune/inflammation response. The new foundation that microarray analysis has provided will broadly support future research on pineal function. PMID:19622385

Klein, David C.; Bailey, Michael J.; Carter, David A.; Kim, Jong-so; Shi, Qiong; Ho, Anthony; Chik, Constance; Gaildrat, Pascaline; Morin, Fabrice; Ganguly, Surajit; Rath, Martin F.; Møller, Morten; Sugden, David; Rangel, Zoila G.; Munson, Peter J.; Weller, Joan L.; Coon, Steven L.

2009-01-01

165

Impact of Emphysema Heterogeneity on Pulmonary Function  

PubMed Central

Objectives To investigate the association between emphysema heterogeneity in spatial distribution, pulmonary function and disease severity. Methods and Materials We ascertained a dataset of anonymized Computed Tomography (CT) examinations acquired on 565 participants in a COPD study. Subjects with chronic bronchitis (CB) and/or bronchodilator response were excluded resulting in 190 cases without COPD and 160 cases with COPD. Low attenuations areas (LAAs) (?950 Hounsfield Unit (HU)) were identified and quantified at the level of individual lobes. Emphysema heterogeneity was defined in a manner that ranged in value from ?100% to 100%. The association between emphysema heterogeneity and pulmonary function measures (e.g., FEV1% predicted, RV/TLC, and DLco% predicted) adjusted for age, sex, and smoking history (pack-years) was assessed using multiple linear regression analysis. Results The majority (128/160) of the subjects with COPD had a heterogeneity greater than zero. After adjusting for age, gender, smoking history, and extent of emphysema, heterogeneity in depicted disease in upper lobe dominant cases was positively associated with pulmonary function measures, such as FEV1 Predicted (p<.001) and FEV1/FVC (p<.001), as well as disease severity (p<0.05). We found a negative association between HI% , RV/TLC (p<0.001), and DLco% (albeit not a statistically significant one, p?=?0.06) in this group of patients. Conclusion Subjects with more homogeneous distribution of emphysema and/or lower lung dominant emphysema tend to have worse pulmonary function. PMID:25409328

Gu, Suicheng; Leader, Joseph K.; Wang, Xiaohua; Chen, Yahong; Zheng, Bin; Wu, Shandong; Gur, David; Sciurba, Frank; Pu, Jiantao

2014-01-01

166

Hormonal profile impact on female sexual function in young women  

NASA Astrophysics Data System (ADS)

Female sexual function is dependent, in physiological milieu upon hormonal impulses: estradiol, testosterone, cortisol, progesterone, prolactin and TSH. Out study tries to appreciate the impact of testosterone, estradiol and prolactin, the major hormones involved in the sexual response, on the normal sexual function. This parameter is approximated by the value of the total FSFI score, a validated international structured interview.

Stoian, Dana; Craciunescu, Mihalea; Craina, Marius; Pater, Liana; Pater, Flavius

2014-12-01

167

Impact of gynecological surgery on female sexual function  

Microsoft Academic Search

Sexual function is complex and involves interaction of many factors, including emotional connection, body image, intact physical response and partner sexual function. Disease processes such as abnormal uterine bleeding, endometriosis, urinary incontinence and pelvic organ prolapse may have a negative impact on various parameters of sexual health. Gynecological surgery to address these common complaints may correct the pathological process. However,

R N Pauls

2010-01-01

168

Colombian ocean waves and coasts modeled by special functions  

NASA Astrophysics Data System (ADS)

Modeling the ocean bottom and surface of both Atlantic and Pacific Oceans near the Colombian coast is a subject of increasing attention due to the possibility of finding oil deposits that haven't been discovered, and as a way of monitoring the ocean limits of Colombia with other countries not only covering the possibility of naval intrusion but as a chance to detect submarine devices that are used by illegal groups for different unwished purposes. In the development of this topic it would be necessary to use Standard Hydrodynamic Equations to model the mathematical shape of ocean waves that will take differential equations forms. Those differential equations will be solved using computer algebra software and methods. The mentioned solutions will involve the use of Special Functions such as Bessel Functions, Whittaker, Heun, and so on. Using the Special Functions mentioned above, the obtained results will be simulated by numerical methods obtaining the typical patterns around the Colombian coasts (both surface and bottom). Using this simulation as a non-perturbed state, any change in the patter could be taken as an external perturbation caused by a strange body or device in an specific area or region modeled, building this simulation as an ocean radar or an unusual object finder. It's worth mentioning that the use of stronger or more rigorous methods and more advanced Special Functions would generate better theoretical results, building a more accurate simulation model that would lead to a finest detection.

Duque Tisnés, Simón

2013-06-01

169

Expansive waves of arts festivals. Approaches in impact studies  

Microsoft Academic Search

Having examined the conceptualisation of economic impact studies as well as the underlying methodological aspects, this paper analyses the following three economic impact studies of arts festivals: European Capital of Culture Salamanca 2002 (Spain), XI Festival de Flamenco de Jerez (Spain), and Glastonbury Music Festival (UK). The analysed data are mainly derived from the studies carried out by various researchers

Colombo Alba

2009-01-01

170

The effect of wave function orthogonality on the simultaneous ionization and excitation of helium  

NASA Astrophysics Data System (ADS)

Within the framework of the first-order Born approximation, the triple differential cross sections (TDCSs) for simultaneous ionization and excitation of helium are calculated. The wave function of the ejected electron is chosen to be orthogonal or non-orthogonal to the wave function of the bound electron before ionization. It is found that the orthogonality has a strong effect on the TDCS, especially when plane waves and Coulomb waves are used to describe the projectile and the ejected electron.

Liu, Li-Juan; Jia, Chang-Chun; Zhang, Li-Min; Chen, Jiao-Jiao; Chen, Zhang-Jin

2013-10-01

171

Impact of Locally Suppressed Wave sources on helioseismic travel times  

E-print Network

Wave travel-time shifts in the vicinity of sunspots are typically interpreted as arising predominantly from magnetic fields, flows, and local changes in sound speed. We show here that the suppression of granulation related wave sources in a sunspot can also contribute significantly to these travel-time shifts, and in some cases, an asymmetry between in and outgoing wave travel times. The tight connection between the physical interpretation of travel times and source-distribution homogeneity is confirmed. Statistically significant travel-time shifts are recovered upon numerically simulating wave propagation in the presence of a localized decrease in source strength. We also demonstrate that these time shifts are relatively sensitive to the modal damping rates; thus we are only able to place bounds on the magnitude of this effect. We see a systematic reduction of 10-15 seconds in $p$-mode mean travel times at short distances ($\\sim 6.2$ Mm) that could be misinterpreted as arising from a shallow (thickness of 1.5 Mm) increase ($\\sim$ 4%) in the sound speed. At larger travel distances ($\\sim 24$ Mm) a 6-13 s difference between the ingoing and outgoing wave travel times is observed; this could mistakenly be interpreted as being caused by flows.

S. M. Hanasoge; S. Couvidat; S. P. Rajaguru; A. C. Birch

2007-07-10

172

Impact of complex blast waves on the human head: a computational study.  

PubMed

Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head-helmet model for blast impact analyses in Abaqus(TM) (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330?kPa is registered at the parietal lobe which exceeds the 235?kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at the temporal and parietal lobes when compared with results from the single frontal blast case. By analyzing the pressure wave flow surrounding the head and correlating them with the consequential evolution of ICP and skull stress, the paper provides insights into the interaction mechanics between the concomitant blast waves and the biological head model. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25132676

Tan, Long Bin; Chew, Fatt Siong; Tse, Kwong Ming; Chye Tan, Vincent Beng; Lee, Heow Pueh

2014-12-01

173

Newton force from wave function collapse: speculation and test  

E-print Network

The Diosi-Penrose model of quantum-classical boundary postulates gravity-related spontaneous wave function collapse of massive degrees of freedom. The decoherence effects of the collapses are in principle detectable if not masked by the overwhelming environmental decoherence. But the DP (or any other, like GRW, CSL) spontaneous collapses are not detectable themselves, they are merely the redundant formalism of spontaneous decoherence. To let DP collapses become testable physics, recently we extended the DP model and proposed that DP collapses are responsible for the emergence of the Newton gravitational force between massive objects. We identified the collapse rate, possibly of the order of 1/ms, with the rate of emergence of the Newton force. A simple heuristic emergence (delay) time was added to the Newton law of gravity. This non-relativistic delay is in peaceful coexistence with Einstein's relativistic theory of gravitation, at least no experimental evidence has so far surfaced against it. We derive new p...

Diósi, Lajos

2013-01-01

174

Wave functions of hot excitons in semiconductors with degenerate bands  

SciTech Connect

Hot excitons in direct-gap cubic semiconductors with a degenerate valence band are considered. Corrections to the model of independent excitonic branches in terms of the small parameter {Dirac_h}/Ka{sub B}, where K is the exciton momentum and a{sub B} is the Bohr radius, are determined. The corrections take into account the internal motion of particles in the exciton. It is shown that the internal motion mixes the states of light and heavy holes in the exciton wave function. As a result, the processes of forward scattering of excitons with transitions between different excitonic branches become allowed. The consideration is concerned with the region of kinetic energies no higher than the spin-orbit splitting in the valence band. The dispersion relation for holes is described in the spherical Kohn-Luttinger model (the 4 x 4 matrix)

Efanov, A. V. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)], E-mail: efanov@isp.nsc.ru

2008-06-15

175

Two dimensional prolate spheroidal wave functions for MRI  

NASA Astrophysics Data System (ADS)

The tradeoff between spatial and temporal resolution is often used to increase data acquisition speed for dynamic MR imaging. Reduction of the k-space sampling area, however, leads to stronger partial volume and truncation effects. A two dimensional prolate spheroidal wave function (2D-PSWF) method is developed to address these problems. Utilizing prior knowledge of a given region of interest (ROI) and the spatial resolution requirement as constraints, this method tailors the k-space sampling area with a matching 2D-PSWF filter so that optimal signal concentration and minimal truncation artifacts are achieved. The k-space sampling area is reduced because the shape and size of the sampling area match the resolution posed by the non-rectangular shape of a convex ROI. The 2D-PSWF method offers an efficient way for spatial and temporal tradeoff with minimal penalty due to truncation, and thus, it promises a wide range of applications in MRI research.

Yang, Qing X.; Lindquist, Martin A.; Shepp, Lawrence; Zhang, Cun-Hui; Wang, Jianli; Smith, Michael B.

2002-09-01

176

Impact of ozone depletion on immune function  

SciTech Connect

Depletion of stratospheric ozone is expected to lead to an increase in the amount of UV-B radiation present in sunlight. In addition to its well known ability to cause skin cancer, UV-B radiation has been shown to alter the immune system. The immune system is the body's primary defense mechanism against infectious diseases and protects against the development of certain types of cancer. Any impairment of immune function may jeopardize health by increasing susceptibility to infectious diseases, increasing the severity of infections, or delaying recovery for infections. In addition, impaired immune function can increase the incidence of certain cancers, particularly cancers of the skin. Research carried out with laboratory animals over the past 15 years has demonstrated that exposure of the skin to UV-B radiation can suppress certain types of immune responses. These include rejection of UV-induced skin cancers and melanomas, contact allergy reactions to chemicals, delayed-type hypersensitivity responses to microbial and other antigens, and phagocytosis and elimination of certain bacteria from lymphoid tissues. Recent studies with mycobacterial infection of mice demonstrated that exposure to UV-B radiation decreased the delayed hypersensitivity response to mycobacterial antigens and increased the severity of infection. In humans, UV-B radiation has also been shown to impair the contact allergy response. These studies demonstrate that UV radiation can decrease immune responses in humans and laboratory and raise the possibility that increased exposure to UV-B radiation could adversely affect human health by increasing the incidence or severity of certain infectious diseases.

Jeevan, A.; Kripke, M.L. (Univ. of Texas, Houston, TX (United States). Dept. of Immunology)

1993-06-01

177

The impact of density heterogeneities on seismic wave propagation  

NASA Astrophysics Data System (ADS)

Using 3D numerical simulations of seismic wave propagation in heterogeneous media, we systematically compare the imprints of heterogeneities of different type (and particularly density heterogeneities) on synthetic seismograms. Lateral density variations are the source of mass transport in the Earth at all scales, acting as drivers of convective motion in the mantle. However, the density structure of the Earth remains largely unknown since classic seismic observables and gravity provide only weak constraints with strong trade-offs. Current density models are therefore often based on velocity scaling, making strong assumptions on the origin of structural heterogeneities, which may not necessarily be true. We propose to develop a seismic tomography technique that directly inverts for density, using complete seismograms rather than arrival times of certain waves only. The first task in this challenge is to systematically study the imprints of density on synthetic seismograms. In this context, our study aims to compare the significance of density heterogeneities relative to velocity heterogeneities, and to design a numerical experiment with a source-receiver configuration particularly sensitive to density. To compute the full seismic wavefield in a 3D heterogeneous medium without making significant approximations, we use numerical wave propagation based on a spectral-element discretization of the seismic wave equation. We consider a 2000 by 1000 km wide and 500 km deep spherical section, with the 1D Earth model ak135 as a background. Onto this we superimpose 3D Gaussian-shaped perturbations of different type (P, SV, SH velocities and density) for depths in the range from 10 km to 70 km. The choice of depth in which the 3D heterogeneities were placed (10 km - 70 km) was dictated by the surface wave sensitivity to density. For each depth we perform 4 wave propagation simulations corresponding to 4 different types of heterogeneities, and calculate surface wave sensitivity kernels. We compare the synthetic seismograms for different types of heterogeneities with seismograms for the 1D reference model, using various misfit criteria, including weighted envelope and phase differences based on continuous wavelet transforms. Our preliminary analyses indicate that density variations do leave a noticeable mark on seismograms, which is of the same order of magnitude as the one from velocity variations. This suggests that the solution of the seismic inverse problem for density may become feasible.

P?onka, Agnieszka; Fichtner, Andreas

2014-05-01

178

Using soil functional indices to assess wildfire impact  

NASA Astrophysics Data System (ADS)

Disturbance impact on ecosystem are often based on functional indicators, which provide integrated and yet simple and affordable measures of key ecosystem functions. In this work, we studied the amount of change (resistance) and the recovery (resilience) of soil functions after fire as a function of vegetation type for a variety of Mediterranean shrublands. We used the Landscape Functional Analysis methodology to assess soil stability, water infiltration, and nutrient cycling functions for different types of vegetation patches and for bare-soil interpatches in repeatedly burned shrubland communities two weeks before, and two and nine months after experimental fires. We assessed the impact of fire on soil functions using resistance and resilience indices. The resistance and resilience of soil surface functions to fire was mediated by vegetation traits associated to the fuel structure and the post-fire regenerative strategy of the species. Resistance was higher in vegetation patches that accumulated low contents of fine dead fuel, whereas resilience was higher in patches of resprouter species. The variation in resistance and resilience of soil functions to fire in Mediterranean shrublands depends greatly on variation in fire-related plant structural and functional traits. Although originally designed for the assessment of dryland ecosystems LFA has proved to have great potential for the assessment of the soil functional status of recently burned areas.

López-Poma, Rosario; Mayor, Ángeles G.; Bautista, Susana

2014-05-01

179

Epicenter Location of Regional Seismic Events Using Love Wave and Rayleigh Wave Ambient Seismic Noise Green's Functions  

NASA Astrophysics Data System (ADS)

We describe a novel method to locate regional seismic events based on exploiting Empirical Green's Functions (EGF) that are produced from ambient seismic noise. Elastic EGFs between pairs of seismic stations are determined by cross-correlating long time-series of ambient noise recorded at the two stations. The EGFs principally contain Rayleigh waves on the vertical-vertical cross-correlations and Love waves on the transverse-transverse cross-correlations. Earlier work (Barmin et al., "Epicentral location based on Rayleigh wave empirical Green's functions from ambient seismic noise", Geophys. J. Int., 2011) showed that group time delays observed on Rayleigh wave EGFs can be exploited to locate to within about 1 km moderate sized earthquakes using USArray Transportable Array (TA) stations. The principal advantage of the method is that the ambient noise EGFs are affected by lateral variations in structure similarly to the earthquake signals, so the location is largely unbiased by 3-D structure. However, locations based on Rayleigh waves alone may be biased by more than 1 km if the earthquake depth is unknown but lies between 2 km and 7 km. This presentation is motivated by the fact that group time delays for Love waves are much less affected by earthquake depth than Rayleigh waves; thus exploitation of Love wave EGFs may reduce location bias caused by uncertainty in event depth. The advantage of Love waves to locate seismic events, however, is mitigated by the fact that Love wave EGFs have a smaller SNR than Rayleigh waves. Here, we test the use of Love and Rayleigh wave EGFs between 5- and 15-sec period to locate seismic events based on the USArray TA in the western US. We focus on locating aftershocks of the 2008 M 6.0 Wells earthquake, mining blasts in Wyoming and Montana, and small earthquakes near Norman, OK and Dallas, TX, some of which may be triggered by hydrofracking or injection wells.

Levshin, A. L.; Barmin, M. P.; Moschetti, M. P.; Mendoza, C.; Ritzwoller, M. H.

2011-12-01

180

An assessment of wind forcing impact on a spectral wave model for the Indian Ocean  

NASA Astrophysics Data System (ADS)

The focus of the present study is the assessment of the impact of wind forcing on the spectral wave model MIKE 21 SW in the Indian Ocean region. Three different wind fields, namely the ECMWF analyzed winds, the ECMWF blended winds, and the NCEP blended winds have been used to drive the model. The wave model results have been compared with in-situ observations and satellite altimeter data. This study also evaluated the performance of the wind products during local phenomenon like sea breeze, since it has a significant impact on the wave prediction in the Indian coastal region. Hence we explored the possibility of studying the impact of diurnal variation of winds on coastal waves using different wind fields. An analysis of the model performance has also been made during high wind conditions with the inference that blended winds generate more realistic wave fields in the high wind conditions and are able to produce the growth and decay of waves more realistically.

Remya, P. G.; Kumar, Raj; Basu, Sujit

2014-06-01

181

Impact of cosmic neutrinos on the gravitational-wave background  

SciTech Connect

We obtain the equation governing the evolution of the cosmological gravitational-wave background, accounting for the presence of cosmic neutrinos, up to second order in perturbation theory. In particular, we focus on the epoch during radiation dominance, after neutrino decoupling, when neutrinos yield a relevant contribution to the total energy density and behave as collisionless ultrarelativistic particles. Besides recovering the standard damping effect due to neutrinos, a new source term for gravitational waves is shown to arise from the neutrino anisotropic stress tensor. The importance of such a source term, so far completely disregarded in the literature, is related to the high velocity dispersion of neutrinos in the considered epoch; its computation requires solving the full second-order Boltzmann equation for collisionless neutrinos.

Mangilli, Anna; Bartolo, Nicola; Matarrese, Sabino; Riotto, Antonio [Institute of Space Sciences (CSIC-IEEC) Campus UAB, Torre C5 parell 2. Bellaterra (Barcelona) (Spain); Dipartimento di Fisica 'Galileo Galilei', Universita di Padova, via Marzolo 8, I-35131 Padova (Italy); Dipartimento di Fisica 'Galileo Galilei', Universita di Padova (Italy); INFN, Sezione di Padova, via Marzolo 8, I-35131 Padova (Italy); INFN, Sezione di Padova, via Marzolo 8, I-35131 Padova (Italy); CERN, Theory Division, CH-1211 Geneva 23 (Switzerland)

2008-10-15

182

The impact of tropospheric planetary wave variability on stratospheric ozone  

SciTech Connect

The goal of this project was to improve understanding of the role of the stratosphere in inducing long-term variations of the chemical composition of the troposphere. Changes in stratospheric transport occur on decadel timescales in response to changes in the structure of planetary wave patterns, forced in the troposphere. For many important tracers, such as column amounts of ozone, this variability of the transport leads to changes with signatures very similar to those induced by anthropogenic releases of chemicals into the atmosphere. During this project, a new interactive two-dimensional model of the dynamics, chemistry and radiation of the stratosphere was developed. The model was used to interpret available data of tracers. It was found that a fairly coherent picture of tracer distributions is obtained when a layer of reduced gravity wave drag is assumed for the lower stratosphere. The results suggest that the power of models to predict variability in tracer transport in the upper troposphere and lower stratosphere is limited until current theories of gravity wave breaking have been refined.

McElroy, Michael B.; Schneider, Hans R.

2002-06-25

183

Planetary wave reflection and its impact on tropospheric cold weather over Asia during January 2008  

NASA Astrophysics Data System (ADS)

Reflection of stratospheric planetary waves and its impact on tropospheric cold weather over Asia during January 2008 were investigated by applying two dimensional Eliassen-Palm (EP) flux and three-dimensional Plumb wave activity fluxes. The planetary wave propagation can clearly be seen in the longitude-height and latitude-height sections of the Plumb wave activity flux and EP flux, respectively, when the stratospheric basic state is partially reflective. Primarily, a wave packet emanating from Baffin Island/coast of Labrador propagated eastward, equatorward and was reflected over Central Eurasia and parts of China, which in turn triggered the advection of cold wind from the northern part of the boreal forest regions and Siberia to the subtropics. The wide region of Central Eurasia and China experienced extreme cold weather during the second ten days of January 2008, whereas the extraordinary persistence of the event might have occurred due to an anomalous blocking high in the Urals-Siberia region.

Nath, Debashis; Chen, Wen; Wang, Lin; Ma, Yin

2014-07-01

184

Impact of real-world stress on cardiorespiratory resting function during sleep in daily life.  

PubMed

To examine if real-world stress affects the restorative function of sleep in daily life, we studied the impact of college examinations on cardiorespiratory resting function during sleep. In healthy college students, at 1 week before, the day before, and the first day of semester-end examinations pulse wave signal during sleep at their own residences was measured continuously with a wristband-shaped wireless transdermal photoelectric sensor. The cardiorespiratory resting function was assessed quantitatively as the power of a high-frequency component of pulse rate variability, a surrogate measure of respiratory sinus arrhythmia. Changes in anxiety were also evaluated with a state anxiety questionnaire. On the day before the examinations, compared with 1 week before, the score of state anxiety increased and the HF component of pulse rate variability decreased. Among college students, anxiety about college examinations may be accompanied by suppression of the cardiorespiratory resting function during sleep. PMID:18503486

Sakakibara, Masahito; Kanematsu, Takayoshi; Yasuma, Fumihiko; Hayano, Junichiro

2008-07-01

185

Higher twist parton distributions from light-cone wave functions  

SciTech Connect

We explore the possibility to construct higher-twist parton distributions in a nucleon at some low reference scale from convolution integrals of the light-cone wave functions (WFs). To this end we introduce simple models for the four-particle nucleon WFs involving three valence quarks and a gluon with total orbital momentum zero, and estimate their normalization (WF at the origin) using QCD sum rules. We demonstrate that these WFs provide one with a reasonable description of both polarized and unpolarized parton densities at large values of the Bjorken variable x{>=}0.5. Twist-three parton distributions are then constructed as convolution integrals of qqqg and the usual three-quark WFs. The cases of the polarized structure function g{sub 2}(x,Q{sup 2}) and single transverse spin asymmetries are considered in detail. We find that the so-called gluon pole contribution to twist-three distributions relevant for single spin asymmetry vanishes in this model, but is generated perturbatively at higher scales by the evolution, in the spirit of Glueck-Reya-Vogt parton distributions.

Braun, V. M.; Lautenschlager, T.; Pirnay, B. [Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); Manashov, A. N. [Institut fuer Theoretische Physik, Universitaet Regensburg, D-93040 Regensburg (Germany); Department of Theoretical Physics, St. Petersburg State University 199034, St. Petersburg (Russian Federation)

2011-05-01

186

Riemann {zeta} function from wave-packet dynamics  

SciTech Connect

We show that the time evolution of a thermal phase state of an anharmonic oscillator with logarithmic energy spectrum is intimately connected to the generalized Riemann {zeta} function {zeta}(s,a). Indeed, the autocorrelation function at a time t is determined by {zeta}({sigma}+i{tau},a), where {sigma} is governed by the temperature of the thermal phase state and {tau} is proportional to t. We use the JWKB method to solve the inverse spectral problem for a general logarithmic energy spectrum; that is, we determine a family of potentials giving rise to such a spectrum. For large distances, all potentials display a universal behavior; they take the shape of a logarithm. However, their form close to the origin depends on the value of the Hurwitz parameter a in {zeta}(s,a). In particular, we establish a connection between the value of the potential energy at its minimum, the Hurwitz parameter and the Maslov index of JWKB. We compare and contrast exact and approximate eigenvalues of purely logarithmic potentials. Moreover, we use a numerical method to find a potential which leads to exact logarithmic eigenvalues. We discuss possible realizations of Riemann {zeta} wave-packet dynamics using cold atoms in appropriately tailored light fields.

Mack, R.; Schleich, W. P. [Institut fuer Quantenphysik, Albert-Einstein-Allee 11, Universitaet Ulm, D-89069 Ulm (Germany); Dahl, J. P. [Institut fuer Quantenphysik, Albert-Einstein-Allee 11, Universitaet Ulm, D-89069 Ulm (Germany); Chemical Physics, Department of Chemistry, Technical University of Denmark, DTU 207, DK-2800 Kgs. Lyngby (Denmark); Moya-Cessa, H. [Institut fuer Quantenphysik, Albert-Einstein-Allee 11, Universitaet Ulm, D-89069 Ulm (Germany); Instituto Nacional de Astrofisica, Optica y Electronica, Apartado Postal 51 Y 216, 72000 Puebla (Mexico); Strunz, W. T. [Institut fuer Theoretische Physik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Walser, R. [Institut fuer Quantenphysik, Albert-Einstein-Allee 11, Universitaet Ulm, D-89069 Ulm (Germany); Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany)

2010-09-15

187

Quantization causes waves:Smooth finitely computable functions are affine  

E-print Network

Given an automaton (a letter-to-letter transducer, a dynamical 1-Lipschitz system on the space $\\mathbb Z_p$ of $p$-adic integers) $\\mathfrak A$ whose input and output alphabets are $\\mathbb F_p=\\{0,1,\\ldots,p-1\\}$, one visualizes word transformations performed by $\\mathfrak A$ by a point set $\\mathbf P(\\mathfrak A)$ in real plane $\\mathbb R^2$. For a finite-state automaton $\\mathfrak A$, it is shown that once some points of $\\mathbf P(\\mathfrak A)$ constitute a smooth (of a class $C^2$) curve in $\\mathbb R^2$, the curve is a segment of a straight line with a rational slope; and there are only finitely many straight lines whose segments are in $\\mathbf{P}(\\mathfrak A)$. Moreover, when identifying $\\mathbf P(\\mathfrak A)$ with a subset of a 2-dimensional torus $\\mathbb T^2\\subset\\mathbb R^3$ (under a natural mapping of the real unit square $[0,1]^2$ onto $\\mathbb T^2$) the smooth curves from $\\mathbf P(\\mathfrak A)$ constitute a collection of torus windings. In cylindrical coordinates either of the windings can be ascribed to a complex-valued function $\\psi(x)=e^{i(Ax-2\\pi B(t))}$ $(x\\in\\mathbb R)$ for suitable rational $A,B(t)$. Since $\\psi(x)$ is a standard expression for a matter wave in quantum theory (where $B(t)=tB(t_0)$), and since transducers can be regarded as a mathematical formalization for causal discrete systems, the paper might serve as a mathematical reasoning why wave phenomena are inherent in quantum systems: This is because of causality principle and the discreteness of matter.

Vladimir Anashin

2015-02-06

188

Waves  

NSDL National Science Digital Library

We will review some basic properties of waves and then further explore sound and light. For a quick overview of some properties of all waves, click on this first site. Make sure you fill out your hand out as you work! Waves and Wave Motion : Describing Waves Practice what you've already learned about waves with this site: Waves This site will let you play around some more with transverse waves: Wave on a String Sound waves are mechanical waves, ...

Petersen, Mrs.

2014-05-27

189

In situ measurements of impact-induced pressure waves in sandstone targets  

NASA Astrophysics Data System (ADS)

the present study we introduce an innovative method for the measurement of impact-induced pressure waves within geological materials. Impact experiments on dry and water-saturated sandstone targets were conducted at a velocity of 4600 m/s using 12 mm steel projectiles to investigate amplitudes, decay behavior, and speed of the waves propagating through the target material. For this purpose a special kind of piezoresistive sensor capable of recording transient stress pulses within solid brittle materials was developed and calibrated using a Split-Hopkinson pressure bar. Experimental impact parameters (projectile size and speed) were kept constant and yielded reproducible signal curves in terms of rise time and peak amplitudes. Pressure amplitudes decreased by 3 orders of magnitude within the first 250 mm (i.e., 42 projectile radii). The attenuation for water-saturated sandstone is higher compared to dry sandstone which is attributed to dissipation effects caused by relative motion between bulk material and interstitial water. The proportion of the impact energy radiated as seismic energy (seismic efficiency) is in the order of 10-3. The present study shows the feasibility of real-time measurements of waves caused by hypervelocity impacts on geological materials. Experiments of this kind lead to a better understanding of the processes in the crater subsurface during a hypervelocity impact.

Hoerth, Tobias; Schäfer, Frank; Nau, Siegfried; Kuder, Jürgen; Poelchau, Michael H.; Thoma, Klaus; Kenkmann, Thomas

2014-10-01

190

Green's function for a metamaterial superlens: Evanescent wave in the image  

NASA Astrophysics Data System (ADS)

We develop a new method to calculate the evanescent wave, the subdivided evanescent waves (SEWs), and the radiative wave, which can be obtained by separating the global field of the image of a metamaterial superlens. The method is based on the Green's function, and it can be applied to other linear systems. This study could help us to investigate the effect of an evanescent wave on a metamaterial superlens directly and give us a new way to design new devices.

Li, Wei; Jiang, Xunya

2012-04-01

191

RESEARCH Open Access Functional impact of Aurora A-mediated  

E-print Network

RESEARCH Open Access Functional impact of Aurora A-mediated phosphorylation of HP1 at serine 83 division, HP1 colocalizes and is phosphorylated at serine 83 (Ser83 ) in G2/M phase by Aurora A. Since Aurora A regulates both cell proliferation and mitotic aberrations, we evaluated the role of HP1

Boyer, Edmond

192

Hadronic Spectra and Light-Front Wave Functions in Holographic QCD  

SciTech Connect

We show how the string amplitude {phi}(z) defined on the fifth dimension in AdS{sub 5} space can be precisely mapped to the light-front wave functions of hadrons in physical space-time. We find an exact correspondence between the holographic variable z and an impact variable {zeta}, which represents the measure of transverse separation of the constituents within the hadrons. In addition, we derive effective four dimensional Schroedinger equations for the bound states of massless quarks and gluons which exactly reproduce the anti-de Sitter conformal field theory results and give a realistic description of the light-quark meson and baryon spectrum as well as the form factors for spacelike Q{sup 2}. Only one parameter which sets the mass scale, {lambda}{sub QCD}, is introduced.

Brodsky, Stanley J. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States); Teramond, Guy F. de [Universidad de Costa Rica, San Jose (Costa Rica)

2006-05-26

193

The East Atlantic - West Russia Teleconnection in the North Atlantic: Climate Impact and Relation to Rossby Wave Propagation  

NASA Technical Reports Server (NTRS)

Large-scale winter teleconnection of the East Atlantic - West Russia (EA-WR) over the Atlantic and surrounding regions is examined in order to quantify its impacts on temperature and precipitation and identify the physical mechanisms responsible for its existence. A rotated empirical orthogonal function (REOF) analysis of the upper-tropospheric monthly height field captures successfully the EA-WR pattern and its interannual variation, with the North Atlantic Oscillation as the first mode. EA-WRs climate impact extends from eastern North America to Eurasia. The positive (negative) EA-WR produces positive (negative) temperature anomalies over the eastern US, western Europe and Russia east of Caspian Sea, with negative (positive) anomalies over eastern Canada, eastern Europe including Ural Mountains and the Middle East. These anomalies are largely explained by lower-tropospheric temperature advections. Positive (negative) precipitation anomalies are found over the mid-latitude Atlantic and central Russia around 60E, where lower-level cyclonic (anticyclonic) circulation anomaly is dominant. The eastern Canada and the western Europe are characterized by negative (positive) precipitation anomalies.The EA-WR is found to be closely associated with Rossby wave propagation. Wave activity fluxes show that it is strongly tied to large-scale stationary waves. Furthermore, a stationary wave model (SWM) forced with vorticity transients in the mid-latitude Atlantic (approximately 40N) or diabatic heat source over the subtropical Atlantic near the Caribbean Sea produces well-organized EA-WR-like wave patterns, respectively. Sensitivity tests with the SWM indicate improvement in the simulation of the EA-WR when the mean state is modified to have a positive NAO component that enhances upper-level westerlies between 40-60N.

Lim, Young-Kwon

2014-01-01

194

Covariant nucleon wave function with S, D, and P-state components  

SciTech Connect

Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.

Franz Gross, G. Ramalho, M. T. Pena

2012-05-01

195

Impact of current-wave interaction on storm surge simulation: A case study for Hurricane Bob  

E-print Network

, especially following Hurricane Katrina in 2005, hurricane-induced storm surge and coastal inundation haveImpact of current-wave interaction on storm surge simulation: A case study for Hurricane Bob,2 Received 2 January 2013; revised 5 April 2013; accepted 18 April 2013; published 30 May 2013. [1] Hurricane

Chen, Changsheng

196

Health monitoring using Lamb waves. Application to the characterization of low impacts in aerospace structures  

Microsoft Academic Search

This work was devoted to the development of a health monitoring system assigned to aerospace applications. The application concerned the detection of low damaging impacts on composite structures due to the extreme sensitivity of this material to this kind of solicitation. The chosen health monitoring was based first on the excitation and reception of Lamb waves along the structure by

Sebastien Grondel; Jamal Assaad; Christophe Delebarre

2002-01-01

197

Impact of large-scale atmospheric refractive structures on optical wave propagation  

NASA Astrophysics Data System (ADS)

Conventional techniques used to model optical wave propagation through the Earth's atmosphere typically as- sume flow fields based on various empirical relationships. Unfortunately, these synthetic refractive index fields do not take into account the influence of transient macroscale and mesoscale (i.e. larger than turbulent microscale) atmospheric phenomena. Nevertheless, a number of atmospheric structures that are characterized by various spatial and temporal scales exist which have the potential to significantly impact refractive index fields, thereby resulting dramatic impacts on optical wave propagation characteristics. In this paper, we analyze a subset of spatio-temporal dynamics found to strongly affect optical waves propagating through these atmospheric struc- tures. Analysis of wave propagation was performed in the geometrical optics approximation using a standard ray tracing technique. Using a numerical weather prediction (NWP) approach, we simulate multiple realistic atmospheric events (e.g., island wakes, low-level jets, etc.), and estimate the associated refractivity fields prior to performing ray tracing simulations. By coupling NWP model output with ray tracing simulations, we demon- strate the ability to quantitatively assess the potential impacts of coherent atmospheric phenomena on optical ray propagation. Our results show a strong impact of spatio-temporal characteristics of the refractive index field on optical ray trajectories. Such correlations validate the effectiveness of NWP models as they offer a more comprehensive representation of atmospheric refractivity fields compared to conventional methods based on the assumption of horizontal homogeneity.

Nunalee, Christopher G.; He, Ping; Basu, Sukanta; Vorontsov, Mikhail A.; Fiorino, Steven T.

2014-10-01

198

Spontaneous generation and impact of inertia-gravity waves in a stratified, two-layer shear flow  

E-print Network

Spontaneous generation and impact of inertia-gravity waves in a stratified, two-layer shear flow P December 2003. [1] Inertia-gravity waves exist ubiquitously throughout the stratified parts inertia-gravity waves are generated as spontaneous adjustment radiation by an evolving large- scale mode

Williams, Paul

199

Matter Density and Relativistic Models of Wave Function Collapse Daniel Bedingham  

E-print Network

) Mathematical models for the stochastic evolution of wave functions that combine the unitary evolution according with a fully relativistic law for the wave function evolution, a problem with relativity remains: Different. We show that the predictions that follow from this proposal agree with all known experimental facts

Goldstein, Sheldon

200

Quantum Monte Carlo: Direct calculation of corrections to trial wave functions and their energies  

E-print Network

ARTICLES Quantum Monte Carlo: Direct calculation of corrections to trial wave functions, Pennsylvania 16802 Received 4 January 2000; accepted 10 March 2000 We report an improved Monte Carlo method Monte Carlo QMC method for the direct calculation of corrections to trial wave functions.1­3 We report

Anderson, James B.

201

Direct Observation of a Breit-Wigner Phase of a Wave Function  

NASA Astrophysics Data System (ADS)

The Breit-Wigner phase of a wave function was obtained by measuring the interference between two independent ionization paths of a molecule. The state of interest was present in only one of the paths, thereby producing a phase shift in the observed signal. An analytical theory was used to determine the phase of the wave function from the observable.

Fiss, Jeanette A.; Khachatrian, Ani; Truhins, Kaspars; Zhu, Langchi; Gordon, Robert J.; Seideman, Tamar

2000-09-01

202

The Influence of Superpositional Wave Function Oscillations on Shor's Quantum Algorithm  

E-print Network

We investigate the influence of superpositional wave function oscillations on the performance of Shor's quantum algorithm for factorization of integers. It is shown that the wave function oscillations can destroy the required quantum interference. This undesirable effect can be routinely eliminated using a resonant pulse implementation of quantum computation, but requires special analysis for non-resonant implementations.

Berman, G P; Tsifrinovich, V I; Berman, Gennady P.; Doolen, Gary D.; Tsifrinovich, Vladimir I.

2000-01-01

203

The Influence of Superpositional Wave Function Oscillations on Shor's Quantum Algorithm  

E-print Network

We investigate the influence of superpositional wave function oscillations on the performance of Shor's quantum algorithm for factorization of integers. It is shown that the wave function oscillations can destroy the required quantum interference. This undesirable effect can be routinely eliminated using a resonant pulse implementation of quantum computation, but requires special analysis for non-resonant implementations.

Gennady P. Berman; Gary D. Doolen; Vladimir I. Tsifrinovich

1999-06-14

204

High-Frequency Asymptotic Expansions for Certain Prolate Spheroidal Wave Functions  

Microsoft Academic Search

Prolate Spheroidal Wave Functions (PSWFs) are a well-studied subject with applications in signal processing, wave propagation, antenna theory, etc. Originally introduced in the context of separation of variables for certain partial differential equations, PSWFs became an important tool for the analysis of band-limited functions after the famous series of articles by Slepian et al. The popularity of PSWFs seems likely

Hong Xiao; Vladimir Rokhlin

2003-01-01

205

An entropy regularization method applied to the identification of wave distribution function  

E-print Network

An entropy regularization method applied to the identification of wave distribution function electromagnetic field measurements. It is based on the wave distribution function (WDF) concept. To assess its suitability and efficiency, the algorithm is applied to experimental data that has already been analyzed using

Santolik, Ondrej

206

Composition of the ^24O Ground State Wave Function  

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical evidence points to a closed shell at N = 16 for the neutron-rich oxygen isotopes based on the measured and predicted excitation energy of the first-excited 2^+ state in ^24O and the energy gap between the ?(0d3/2) and ?(1s1/2) single-particle states. This work seeks to test this assertion by measuring the cross section for neutron knockout from the ^24O ground state to the ground and first-excited states of ^23O (which immediately decays to the ground state of ^22O through neutron emission). From this we can infer the composition of the ^24O ground state wave function. ^24O nuclei were produced at the National Superconducting Cyclotron Lab (NSCL) at Michigan State University via fragmentation of a ^48Ca beam on a 1316 mg/cm^2 Be target, and bombarded a 481 mg/cm^2 Be target downstream to induce knockout reactions. Fragment nuclei (neutron decays) were detected by a system of charged-particle detectors (the Modular Neutron Array (MoNA)). The current status of the analysis will be discussed, including the identification of oxygen fragments, the calibrations for timing and position measurements using MoNA, and the determination of the relevant spectroscopic factors of interest.

Scotten, R. A.; Traynor, E.; Deyoung, P. A.; Islam, N. T.; Haring-Kaye, R. A.

2012-10-01

207

Newton force from wave function collapse: speculation and test  

NASA Astrophysics Data System (ADS)

The Diosi-Penrose model of quantum-classical boundary postulates gravity-related spontaneous wave function collapse of massive degrees of freedom. The decoherence effects of the collapses are in principle detectable if not masked by the overwhelming environmental decoherence. But the DP (or any other, like GRW, CSL) spontaneous collapses are not detectable themselves, they are merely the redundant formalism of spontaneous decoherence. To let DP collapses become testable physics, recently we extended the DP model and proposed that DP collapses are responsible for the emergence of the Newton gravitational force between massive objects. We identified the collapse rate, possibly of the order of 1/ms, with the rate of emergence of the Newton force. A simple heuristic emergence (delay) time was added to the Newton law of gravity. This non-relativistic delay is in peaceful coexistence with Einstein's relativistic theory of gravitation, at least no experimental evidence has so far surfaced against it. We derive new predictions of such a 'lazy' Newton law that will enable decisive laboratory tests with available technologies. The simple equation of 'lazy' Newton law deserves theoretical and experimental studies in itself, independently of the underlying quantum foundational considerations.

Diósi, Lajos

2014-04-01

208

Epistemology of Wave Function Collapse in Quantum Physics  

E-print Network

Among several possibilities for what reality could be like in view of the empirical facts of quantum mechanics, one is provided by theories of spontaneous wave function collapse, the best known of which is the Ghirardi-Rimini-Weber (GRW) theory. We show mathematically that in GRW theory (and similar theories) there are limitations to knowledge, that is, inhabitants of a GRW universe cannot find out all the facts true about their universe. As a specific example, they cannot accurately measure the number of collapses that a given physical system undergoes during a given time interval; in fact, they cannot reliably measure whether one or zero collapses occur. Put differently, in a GRW universe certain meaningful, factual questions are empirically undecidable. We discuss several types of limitations to knowledge and compare them with those in other (no-collapse) versions of quantum mechanics, such as Bohmian mechanics. Most of our results also apply to observer-induced collapses as in orthodox quantum mechanics (as opposed to the spontaneous collapses of GRW theory).

Charles Wesley Cowan; Roderich Tumulka

2014-02-19

209

Quantum anti-Zeno effect without wave function reduction  

PubMed Central

We study the measurement-induced enhancement of the spontaneous decay for a two-level subsystem, where measurements are treated as couplings between the excited state and an auxiliary state rather than the von Neumann's wave function reduction. The photon radiated in a fast decay of the atom, from the auxiliary state to the excited state, triggers a quasi-measurement, as opposed to a projection measurement. Our use of the term “quasi-measurement” refers to a “coupling-based measurement”. Such frequent quasi-measurements result in an exponential decay of the survival probability of atomic initial state with a photon emission following each quasi-measurement. Our calculations show that the effective decay rate is of the same form as the one based on projection measurements. The survival probability of the atomic initial state obtained by tracing over all the photon states is equivalent to that of the atomic initial state with a photon emission following each quasi-measurement.

Ai, Qing; Xu, Dazhi; Yi, Su; Kofman, A. G.; Sun, C. P.; Nori, Franco

2013-01-01

210

Two dimensional prolate spheroidal wave functions for MRI.  

PubMed

The tradeoff between spatial and temporal resolution is often used to increase data acquisition speed for dynamic MR imaging. Reduction of the k-space sampling area, however, leads to stronger partial volume and truncation effects. A two dimensional prolate spheroidal wave function (2D-PSWF) method is developed to address these problems. Utilizing prior knowledge of a given region of interest (ROI) and the spatial resolution requirement as constraints, this method tailors the k-space sampling area with a matching 2D-PSWF filter so that optimal signal concentration and minimal truncation artifacts are achieved. The k-space sampling area is reduced because the shape and size of the sampling area match the resolution posed by the non-rectangular shape of a convex ROI. The 2D-PSWF method offers an efficient way for spatial and temporal tradeoff with minimal penalty due to truncation, and thus, it promises a wide range of applications in MRI research. PMID:12419670

Yang, Qing X; Lindquist, Martin A; Shepp, Lawrence; Zhang, Cun-Hui; Wang, Jianli; Smith, Michael B

2002-01-01

211

Impact of IQ Discrepancy on Executive Function in High-Functioning Autism: Insight into Twice Exceptionality  

ERIC Educational Resources Information Center

We examined the impact of IQ discrepancy (IQD) within (1) and above (1+) one standard deviation on executive function in HFA using the BRIEF. We hypothesized that IQD would benefit executive function. IQD 1 is hallmarked by deficits in BRIEF indices and subscales inhibit, shift, initiate, working memory, planning and organization, and monitor…

Kalbfleisch, M. Layne; Loughan, Ashlee R.

2012-01-01

212

Impact-induced tensile waves in a kind of phase-transforming materials  

E-print Network

This paper concerns the global propagation of impact-induced tensile waves in a kind of phase-transforming materials. It is well-known that the governing system of partial differential equations is hyperbolic-elliptic and the initial-boundary value problem is not well-posed at all levels of loading. By making use of fully nonlinear stress-strain curve to model this material, Dai and Kong succeeded in constructing a physical solution of the above initial-boundary value problem. For the impact of intermediate range, they assumed that $\\betaimpact problem and consider the propagation of impact-induced tensile waves for all values of the parameters $\\alpha$ and $\\beta$. The physical solutions for all levels of loading are obtained completely.

Shou-Jun Huang

2010-07-23

213

Correlated continuum wave functions for three particles with Coulomb interactions  

Microsoft Academic Search

We present an approximate solution of the Schröautdinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms of

G. Gasaneo; F. D. Colavecchia; C. R. Garibotti; J. E. Miraglia; P. Macri

1997-01-01

214

The function of 'brain waves': a cybernetic model of electroencephalography.  

PubMed

Electroencephalograms recorded from sleeping subjects are reinterpreted, from first principles, to explain the relationship between the observed wave-forms and cerebral processes. The manifestations of narcolepsy, namely, sleep paralysis, hypnopompic hallucinations and cataplexy are consistent with a hypothesis that the disorder is the result of entrainment of cerebral waves, causing almost instantaneous descent into a REM sleep state. PMID:14592793

ben-Aaron, M

2003-01-01

215

Impact on cognitive function-are all statins the same?  

PubMed

Dementia is a major public health concern, affecting an estimated 7% of the population over 65 and 30% over 80 years of age. There is mounting evidence in the literature from meta-analyses of high-quality prospective cohort studies that statins may have a positive impact in reducing the incidence of dementia. Little is known, however, on whether certain types of statins are more impactful than others. This narrative review specifically explores the various properties of different statin types and whether these differences lead to a clinically significant differential impact on cognitive function. We critically evaluate the literature, emphasizing interesting and important new findings, and overall aim to bring the reader up-to-date on evidence-based recommendations. PMID:25398642

Shah, Nishant P; Swiger, Kristopher J; Martin, Seth S

2015-01-01

216

Covariant spectator theory of $np$ scattering:\\\\ Effective range expansions and relativistic deuteron wave functions  

SciTech Connect

We present the effective range expansions for the 1S0 and 3S1 scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with \\chi^2/N{data} \\simeq 1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.

Franz Gross, Alfred Stadler

2010-09-01

217

Topological and entanglement properties of resonating valence bond wave functions  

NASA Astrophysics Data System (ADS)

We examine in details the connections between topological and entanglement properties of short-range resonating valence bond (RVB) wave functions using projected entangled pair states (PEPS) on kagome and square lattices on (quasi)infinite cylinders with generalized boundary conditions (and perimeters with up to 20 lattice spacings). By making use of disconnected topological sectors in the space of dimer lattice coverings, we explicitly derive (orthogonal) “minimally entangled” PEPS RVB states. For the kagome lattice, using the quantum Heisenberg antiferromagnet as a reference model, we obtain the finite-size scaling with increasing cylinder perimeter of the vanishing energy separations between these states. In particular, we extract two separate (vanishing) energy scales corresponding (i) to insert a vison line between the two ends of the cylinder and (ii) to pull out and freeze a spin at either end. We also investigate the relations between bulk and boundary properties and show that, for a bipartition of the cylinder, the boundary Hamiltonian defined on the edge can be written as a product of a highly nonlocal projector, which fundamentally depends upon boundary conditions, with an emergent (local) SU(2)-invariant one-dimensional (superfluid) t-J Hamiltonian, which arises due to the symmetry properties of the auxiliary spins at the edge. This multiplicative structure, a consequence of the disconnected topological sectors in the space of dimer lattice coverings, is characteristic of the topological nature of the states. For minimally entangled RVB states, it is shown that the entanglement spectrum, which reflects the properties of the (gapless or gapped) edge modes, is a subset of the spectrum of the local Hamiltonian, e.g., half of it for the kagome RVB state, providing a simple argument on the origin of the topological entanglement entropy S0=-ln2 of the Z2 spin liquid. We propose to use these features to probe topological phases in microscopic Hamiltonians, and some results are compared to existing density matrix renormalization group data.

Poilblanc, Didier; Schuch, Norbert; Pérez-García, David; Cirac, J. Ignacio

2012-07-01

218

Ephemeral penalty functions for contact-impact dynamics  

NASA Technical Reports Server (NTRS)

The use of penalty functions to treat a class of structural contact-impact problems is investigated, with emphasis on ones in which the impact phenomena are primarily nondestructive in nature and in which only the gross characterization of the response is required. The dynamic equations of motion are integrated by the difference method. The penalty is represented as an ephemeral fictitious nonlinear spring that is inserted on anticipation of contact. The magnitude and variation of the penalty force is determined through energy balancing considerations. The 'bell shape' of the penalty force function for positive gap was found to be satisfactory, as it depends on only two parameters that can be directly assigned the physical meaning of force and distance. The determination of force law parameters by energy balance worked well. The incorporation of restitution coefficients by the area balancing method yielded excellent results, and no substantial modifications are anticipated. Extensional penalty springs are obviously sufficient for the simple examples treated.

De La Fuente, Horacio M.; Felippa, Carlos A.

1991-01-01

219

Impact of large-x resummation on parton distribution functions  

E-print Network

We investigate the effect of large-x resummation on parton distributions by performing a fit of Deep Inelastic Scattering data from the NuTeV, BCDMS and NMC collaborations, using NLO and NLL soft-resummed coefficient functions. Our results show that soft resummation has a visible impact on quark densities at large x. Resummed parton fits would therefore be needed whenever high precision is required for cross sections evaluated near partonic threshold.

Gennaro Corcella; Lorenzo Magnea

2005-07-04

220

The impact of consecutive freshwater trimix dives at altitude on human cardiovascular function.  

PubMed

Self-contained underwater breathing apparatus (SCUBA) diving is regularly associated with numerous asymptomatic changes in cardiovascular function. Freshwater SCUBA diving presents unique challenges compared with open sea diving related to differences in water density and the potential for dive locations at altitude. The aim of this study was to evaluate the impact of freshwater trimix diving at altitude on human cardiovascular function. Ten divers performed two dives in consecutive days at 294 m altitude with the surface interval of 24 h. Both dives were at a depth of 45 m with total dive time 29 and 26 min for the first and second dive, respectively. Assessment of venous gas embolization, hydration status, cardiac function and arterial stiffness was performed. Production of venous gas emboli was low, and there were no significant differences between the dives. After the first dive, diastolic blood pressure was significantly reduced, which persisted up to 24 h. Left ventricular stroke volume decreased, and heart rate increased after both dives. Pulse wave velocity was unchanged following the dives. However, the central and peripheral augmentation index became more negative after both dives, indicating reduced wave reflection. Ejection duration and round trip travel time were prolonged 24 h after the first dive, suggesting longer-lasting suppression of cardiac and endothelial function. This study shows that freshwater trimix dives with conservative profiles and low venous gas bubble loads can result in multiple asymptomatic acute cardiovascular changes some of which were present up to 24 h after dive. PMID:24528802

Lozo, Mislav; Madden, Dennis; Gunjaca, Grgo; Ljubkovic, Marko; Marinovic, Jasna; Dujic, Zeljko

2014-02-16

221

Gravity wave propagation in the realistic atmosphere based on a three-dimensional transfer function model  

NASA Astrophysics Data System (ADS)

In order to study the filter effect of the background winds on the propagation of gravity waves, a three-dimensional transfer function model is developed on the basis of the complex dispersion relation of internal gravity waves in a stratified dissipative atmosphere with background winds. Our model has successfully represented the main results of the ray tracing method, e.g. the trend of the gravity waves to travel in the anti-windward direction. Furthermore, some interesting characteristics are manifest as follows: (1) The method provides the distribution characteristic of whole wave fields which propagate in the way of the distorted concentric circles at the same altitude under the control of the winds. (2) Through analyzing the frequency and wave number response curve of the transfer function, we find that the gravity waves in a wave band of about 15-30 min periods and of about 200-400 km horizontal wave lengths are most likely to propagate to the 300-km ionospheric height. Furthermore, there is an obvious frequency deviation for gravity waves propagating with winds in the frequency domain. The maximum power of the transfer function with background winds is smaller than that without background winds. (3) The atmospheric winds may act as a directional filter that will permit gravity wave packets propagating against the winds to reach the ionospheric height with minimum energy loss.

Sun, L.; Wan, W.; Ding, F.; Mao, T.

2007-10-01

222

Impact of genomic damage and ageing on stem cell function  

PubMed Central

Impairment of stem cell function contributes to the progressive deterioration of tissue maintenance and repair with ageing. Evidence is mounting that age-dependent accumulation of DNA damage in both stem cells and cells that comprise the stem cell microenvironment are partly responsible for stem cell dysfunction with ageing. Here, we review the impact of the various types of DNA damage that accumulate with ageing on stem cell functionality, as well as the development of cancer. We discuss DNA-damage-induced cell intrinsic and extrinsic alterations that influence these processes, and review recent advances in understanding systemic adjustments to DNA damage and how they affect stem cells. PMID:24576896

Behrens, Axel; van Deursen, Jan M.; Rudolph, K. Lenhard; Schumacher, Björn

2014-01-01

223

ASYMPTOTIC FORMS OF COULOMB WAVE FUNCTIONS, I A. ERDELYI, M. KENNEDY and].L. MCGREGOR  

E-print Network

of Coulomb wave functions follow from the theory of confluent hypergeometric functions [16], [8]. It follows from the theory of confluent hypergeometric functions that for L ~ - ~ there exists a solution of (1 on asymptotic forms of confluent hypergeometric functions is summarized in Buchholz's book ([8], Chapter IV

Winfree, Erik

224

Coherent cooling of atoms in a frequency-modulated standing laser wave: Wave function and stochastic trajectory approaches  

NASA Astrophysics Data System (ADS)

The wave function of a moderately cold atom in a stationary near-resonant standing light wave delocalizes very fast due to wave packet splitting. However, we show that frequency modulation of the field can suppress packet splitting for some atoms whose specific velocities are in a narrow range. These atoms remain localized in a small space for a long time. We demonstrate and explain this effect numerically and analytically. We also demonstrate that the modulated field can not only trap but also cool the atoms. We perform a numerical experiment with a large atomic ensemble having wide initial velocity and energy distributions. During the experiment, most of atoms leave the wave while the trapped atoms have a narrow energy distribution.

Argonov, V. Yu.

2014-11-01

225

Asymptotic scattering wave function for three charged particles and astrophysical capture processes  

NASA Astrophysics Data System (ADS)

The asymptotic behavior of the wave functions of three charged particles has been investigated. There are two different types of three-body scattering wave functions. The first type of scattering wave function evolves from the incident three-body wave of three charged particles in the continuum. The second type of scattering wave function evolves from the initial two-body incident wave. In this work the asymptotic three-body incident wave has been derived in the asymptotic regions where two particles are close to each other and far away from the third particle. This wave function satisfies the Schrodinger equation up to terms O(1/ r3a ), where rhoalpha is the distance between the center of mass of two particles and the third particle. The derived asymptotic three-body incident wave transforms smoothly into Redmond's asymptotic incident wave in the asymptotic region where all three particles are well separated. For the scattering wave function of the second type the asymptotic three-body scattered wave has been derived in all the asymptotic regions. In the asymptotic region where all three particles well separated, the derived asymptotic scattered wave coincides with the Peterkop asymptotic wave. In the asymptotic regions where two particles are close to each other and far away from the third one, this is a new expression which is free of the logarithmically diverging phase factors that appeared in the Peterkop approach. The derived asymptotic scattered wave resolves a long-standing phase-amplitude ambiguity. Based on these results the expressions for the exact prior and post breakup amplitudes have been obtained. The post breakup amplitude for charged particles has not been known and has been derived for the first time directly from the prior form. It turns out that the post form of the breakup amplitude is given by a surface integral in the six dimensional hyperspace, rather than a volume integral, with the transition operator expressed in terms of the interaction potentials. We also show how to derive a generalized distorted-wave-Born approximation amplitude (DWBA) from the exact prior form of the breakup amplitude. It is impossible to derive the DWBA amplitude from the post form. The three-body Coulomb incident wave is used to calculate the reaction rates of 7Be (ep, e)8B and 7Be(pp, p)8 B nonradiative triple collisions in stellar environments.

Pirlepesov, Fakhriddin

226

Final-state Phi2 wave function in ion-helium collisions  

Microsoft Academic Search

In this work we study the double-differential cross sections (DDCSs) of ejected electrons in single-ionization collisions of protons with helium atoms. The final state of the emitted electron is modeled by the correlated wave function Phi2, a confluent hypergeometric function of two variables. We introduce a series representation of the Phi2 wave function in terms of two-body Coulomb-like states, corresponding

F. D. Colavecchia; G. Gasaneo; C. R. Garibotti

1998-01-01

227

Characteristics of the Wave Function of Coupled Oscillators in Semiquantum Chaos  

E-print Network

Using the method of adiabatic invariants and the Born-Oppenheimer approximation, we have successfully got the excited-state wave functions for a pair of coupled oscillators in the so-called \\textit{semiquantum chaos}. Some interesting characteristics in the \\textit{Fourier spectra} of the wave functions and its \\textit{Correlation Functions} in the regular and chaos states have been found, which offers a new way to distinguish the regular and chaotic states in quantum system.

Gang Wu; Jinming Dong

2007-07-30

228

On Dissipation Function of Ocean Waves due to Whitecapping  

SciTech Connect

The Hasselmann kinetic equation provides a statistical description of waves ensemble. Several catastrophic events are beyond statistical model. In the case of gravity waves on the surface of the deep fluid may be the most frequent and important events of such kind are whitecapping and wave breaking. It was shown earlier that such effects leads to additional dissipation in the energy contaning region around waves spectral peak, which can be simulated by means of empiric dissipative term in kinetic equation. In order to find dependence of this term with respect to nonlinearity in the system (steepness of the surface) we preformed two numerical experiments: weakly nonlinear one in the framework of 3D hydrodynamics and fully nonlinear one for 2D hydrodynamic. In spite of significantly different models and initial conditions, both these experiments yielded close results. Obtained data can be used to define analytical formula for dependence of the dissipative term of dissipation coefficient with respect to mean steepness of the surface.

Zakharov, V. E. [Department of Mathematics, University of Arizona, 617 N. Santa Rita Ave., P.O. Box 210089, Tucson, AZ 85721-0089 (United States); Waves and Solitons LLC, 918 W. Windsong Dr., Phoenix, AZ 85045 (United States); Korotkevich, A. O. [P. N. Lebedev Physical Institute RAS, 53 Leninsky Prosp., GSP-1 Moscow, 119991 (Russian Federation); Department of Mathematics and Statistics, University of New Mexico, MSC03 2150, 1 University of New Mexico, Albuquerque, NM 87131-0001 (United States); L. D. Landau Institute for Theoretical Physics RAS, 2 Kosygin Str., Moscow, 119334 (Russian Federation); Prokofiev, A. O. [L. D. Landau Institute for Theoretical Physics RAS, 2 Kosygin Str., Moscow, 119334 (Russian Federation)

2009-09-09

229

Sea state projections for the North Sea: Impact of climate change on very high waves?  

NASA Astrophysics Data System (ADS)

The research program KLIWAS of the German Federal Ministry of Transport, Building and urban Development investigates the impacts of climate change on waterways and navigation and provides options for adaptations. One aspect of the research task is to analyse climate scenarios for the sea state, eg. Sea wave height (SWH), wave direction and wave periods for the North Sea. Of particular importance for the safety on waterways is the potential change of frequence and magnitude from severe waves. The scenarios together with the wave climate of the recent years will give an approximation of projected changes of the sea state in coastal and open sea areas. Here we show the results for projected changes of medium, high and very high waves in the North Sea for the period 2000-2100 in comparison to 1961-2000, based on the wave model WAM4.5.3 The wave model is driven with wind data from two different regional atmosphere-ocean-models (DMI-HIRHAM and MPI-REMO) in the scenario A1B. The wind data are delivered in a horizontal resolution of about 20 km and a time resolution of one hour, while the wave model provides data of the calculated sea state with a horizontal grid of 5 km and the time resolution of one hour. It is seen, that in the eastern North Sea and especially in the German Bight there is a trend to a increasing of the 99th percentile of SWH, while in the western part the 99th percentile of SWH decreases in the future. These changes are mainly caused by changing wind directions in the future, while the wind speed will be mostly unaltered. Supplementary, it was carried out an extrem value analysis with the same data. Although the very high waves (eg. waves with a return period of 1-, 5-, 10-, up to 100 years) displays a similar behavior as the median or 99th percentile, there are regions in the North Sea (eg. the German Bight) with stronger changes of the higher waves. For all wave heights a strong decadal variability is detected which superimposes the calculated trends.

Möller, Jens; Groll, Nikolaus; Heinrich, Hartmut

2014-05-01

230

Correlated continuum wave functions for three particles with Coulomb interactions  

Microsoft Academic Search

We present an approximate solution of the Schr{umlt o}dinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms

G. Gasaneo; F. D. Colavecchia; C. R. Garibotti; J. E. Miraglia; P. Macri

1997-01-01

231

Shoulder function after extracorporal shock wave therapy for calcific tendinitis  

Microsoft Academic Search

We report a controlled, prospective study that explored the effect of extracorporal shock waves of low-versus highenergy density in patients with chronic shoulder pain and calcific tendinitis. We assigned at random 100 patients who had had calcific tendinitis for more than 12 months to 2 groups to receive shock wave therapy either of a low-or high-energy density. Group 1 received

Jan D Rompe; Rainer Bürger; Christof Hopf; Peer Eysel

1998-01-01

232

Longitudinal wave function control in single quantum dots with an applied magnetic field  

PubMed Central

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots. PMID:25624018

Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A.; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

2015-01-01

233

Coherent molecular transistor: Control through variation of the gate wave function  

SciTech Connect

In quantum interference transistors (QUITs), the current through the device is controlled by variation of the gate component of the wave function that interferes with the wave function component joining the source and the sink. Initially, mesoscopic QUITs have been studied and more recently, QUITs at the molecular scale have been proposed and implemented. Typically, in these devices the gate lead is subjected to externally adjustable physical parameters that permit interference control through modifications of the gate wave function. Here, we present an alternative model of a molecular QUIT in which the gate wave function is directly considered as a variable and the transistor operation is discussed in terms of this variable. This implies that we specify the gate current as well as the phase of the gate wave function component and calculate the resulting current through the source-sink channel. Thus, we extend on prior works that focus on the phase of the gate wave function component as a control parameter while having zero or certain discrete values of the current. We address a large class of systems, including finite graphene flakes, and obtain analytic solutions for how the gate wave function controls the transistor.

Ernzerhof, Matthias, E-mail: Matthias.Ernzerhof@UMontreal.ca [Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Quebec H3C 3J7 (Canada)] [Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Quebec H3C 3J7 (Canada)

2014-03-21

234

Longitudinal wave function control in single quantum dots with an applied magnetic field.  

PubMed

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots. PMID:25624018

Cao, Shuo; Tang, Jing; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

2015-01-01

235

Longitudinal wave function control in single quantum dots with an applied magnetic field  

E-print Network

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted electron-hole alignment along the magnetic field direction. Manipulating the wave function longitudinally not only provides an alternative way to control the charge distribution with magnetic field but also a new method to tune electron-hole interaction in single quantum dots.

Shuo Cao; Jing Tang; Yunan Gao; Yue Sun; Kangsheng Qiu; Yanhui Zhao; Min He; Jin-An Shi; Lin Gu; David A. Williams; Weidong Sheng; Kuijuan Jin; Xiulai Xu

2015-01-29

236

Corotation resonances for gravity waves and their impact on angular momentum transport in stellar interiors  

NASA Astrophysics Data System (ADS)

Gravity waves, which propagate in radiation zones, can extract or deposit angular momentum by radiative and viscous damping. Another process, poorly explored in stellar physics, concerns their direct interaction with the differential rotation and the related turbulence. In this work, we thus study their corotation resonances, also called critical layers, that occur where the Doppler-shifted frequency of the wave approaches zero. First, we study the adiabatic and non-adiabatic propagation of gravity waves near critical layers. Next, we derive the induced transport of angular momentum. Finally, we use the dynamical stellar evolution code STAREVOL to apply the results to the case of a solar-like star. The results depend on the value of the Richardson number at the critical layer. In the first stable case, the wave is damped. In the other unstable and turbulent case, the wave can be reflected and transmitted by the critical layer with a coefficient larger than one: the critical layer acts as a secondary source of excitation for gravity waves. These new results can have a strong impact on our understanding of angular momentum transport processes in stellar interiors along stellar evolution where strong gradients of angular velocity can develop.

Alvan, Lucie; Mathis, Stéphane; Decressin, Thibaut

2014-02-01

237

Impacts and Responses to the 1995 Heat Wave: A Call to Action.  

NASA Astrophysics Data System (ADS)

The short but intense heat wave in mid-July 1995 caused 830 deaths nationally, with 525 of these deaths in Chicago. Many of the dead were elderly. and the event raised great concern over why it happened. Assessment of causes for the heat wave-related deaths in Chicago revealed many factors were at fault, including an inadequate local heat wave warning system, power failures, questionable death assessments, inadequate ambulance service and hospital facilities, the heat island, an aging population, and the inability of many persons to properly ventilate their residences due to fear of crime or a lack of resources for fans or air conditioning. Heat-related deaths appear to be on the increase in the United States. Heat-related deaths greatly exceed those caused by other life-threatening weather conditions. Analysis of the impacts and responses to this heat wave reveals a need to 1) define the heat island conditions during heat waves for all major cities is a means to improve forecasts of threatening conditions, 2) develop a nationally uniform means for classifying heat-related deaths, 3) improve warning systems that are designed around local conditions of large cities, and 4) increase research on the meteorological and climatological aspects of heat stress and heat waves.

Changnon, Stanley A.; Kunkel, Kenneth E.; Reinke, Beth C.

1996-07-01

238

Millimeter-wave nondestructive evaluation of glass fiber/epoxy composites subjected to impact fatigue  

NASA Astrophysics Data System (ADS)

The useful life of a glass fiber/epoxy composite subjected to impact fatigue loading is an important issue in the future design of numerous industrial components. Lifetime predictions have been a problem particularly due to the difficulties encountered in monitoring damage accumulation in composites. It is hypothesized that there is a build up of micro damage, such as matrix micro-cracks and micro-delaminations, even though there is no apparent change in material compliance. A critical level is finally reached at which time the properties of the composite begin to fall and compliance change is evident. In this study the apparent compliance change and the type of damage accumulation is investigated. To measure the compliance change, a test unit was developed that uses a dynamic load measuring system. The load cell measures the load throughout each impact pulse and the compliance and energy absorbed by the specimen is then related to the recorded curve. Initially no change in the impact pulse was apparent; however, after a finite number of cycles the peak load and area under each impact pulse drop, indicating an increase in compliance. Unfortunately, the impact load does not provide information on the form and degree of damage. Thus, millimeter wave nondestructive investigation is used, in conjunction with impact fatigue tests, to examine microstructural aspects of damage initiation and growth. The millimeter wave scanning technique results in detectable damage growth throughout the impact fatigue test. Damage size and growth patterns specific to composites are obvious, and after significant damage can be related to the observable macro damage. Continued development of these investigative techniques promises to enhance the ability of detecting defects and damage growth in fiber reinforced composite materials as well as improving the understanding of impact fatigue initiation in these complex materials.

Radford, Donald W.; Ganchev, Stoyan I.; Qaddoumi, Nasser; Beauregard, Guy; Zoughi, Reza

1994-09-01

239

Detection of gravitational waves in Michelson interferometer by the use of second order correlation functions  

E-print Network

The possibility of measuring the second order correlation function of the gravitational waves detectors' currents or photonumbers, and the observation of the gravitational signals by using a spectrum analyzer is discussed. The method is based on complicated data processing and is expected to be efficient for coherent periodic gravitational waves. It is suggested as an alternative method to the conventional one which is used now in the gravitational waves observatories.

Y. Ben-Aryeh

2006-12-31

240

The Hartle-Hawking wave function in 2d causal set quantum gravity  

E-print Network

We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.

Glaser, Lisa

2014-01-01

241

The Hartle-Hawking wave function in 2d causal set quantum gravity  

E-print Network

We define the Hartle-Hawking no-boundary wave function for causal set quantum gravity over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyse this wave function in non perturbative 2d causal set quantum gravity. Our results provide new insights into the role of quantum gravity in the observable universe. We find that non-manifold contributions to the Hartle-Hawking wave function can play a significant role. These discrete geometries exhibit a rapid spatial expansion with respect to the proper time and also possess a spatial homogeneity consistent with our current understanding of the observable universe.

Lisa Glaser; Sumati Surya

2014-10-31

242

Reconstruction of the time-dependent wave function exclusively from position data.  

PubMed

A method is presented that reconstructs the amplitude and phase of an unknown time-dependent pure-state wave function entirely from experimental position data. No assumptions about the wave function are needed. At a series of times, a large collection of position data is taken, but no measurements of momentum or energy are necessary. The momenta, however, are required for the reconstruction of the wave function and are supplied by analysis of the position data via quantum particle trajectories. Simulations of the method are provided for helium atoms in single and double slit experiments. PMID:22182070

Coffey, Timothy M; Wyatt, Robert E; Schieve, Wm C

2011-12-01

243

Green’s functions extraction and surface-wave tomography from microseisms in southern California  

Microsoft Academic Search

We use crosscorrelations of seismic noise data from 151 stations in southern California to extract the group velocities of surface waves between the station pairs for the purpose of determining the surface-wave velocity structure. We devel- oped an automated procedure for estimating the Green's functions and subsequent tomographic inversion from the 11,325 station pairs based on the characteristics of the

Peter Gerstoft; Karim G. Sabra; Philippe Roux; W. A. Kuperman; Michael C. Fehler

2006-01-01

244

The k-model - green's function based analysis of surface acoustic wave devices  

Microsoft Academic Search

We have derived a model for the analysis of surface acoustic wave devices based on relating the surface potential adherent to surface acoustic waves propagating on a piezoelectric substrate and applied transducer potentials. Device structures are analyzed on the basis of the Green's function, including end effects, electrical loading, mass loading effects, electrode resis- tance, dispersion, and propagation loss, leading

J. H. Kuypers; D. A. Eisele; L. M. Reindl

2005-01-01

245

Influence of coastal vegetation on the 2004 tsunami wave impact in west Aceh  

PubMed Central

In a tsunami event human casualties and infrastructure damage are determined predominantly by seaquake intensity and offshore properties. On land, wave energy is attenuated by gravitation (elevation) and friction (land cover). Tree belts have been promoted as “bioshields” against wave impact. However, given the lack of quantitative evidence of their performance in such extreme events, tree belts have been criticized for creating a false sense of security. This study used 180 transects perpendicular to over 100 km on the west coast of Aceh, Indonesia to analyze the influence of coastal vegetation, particularly cultivated trees, on the impact of the 2004 tsunami. Satellite imagery; land cover maps; land use characteristics; stem diameter, height, and planting density; and a literature review were used to develop a land cover roughness coefficient accounting for the resistance offered by different land uses to the wave advance. Applying a spatial generalized linear mixed model, we found that while distance to coast was the dominant determinant of impact (casualties and infrastructure damage), the existing coastal vegetation in front of settlements also significantly reduced casualties by an average of 5%. In contrast, dense vegetation behind villages endangered human lives and increased structural damage. Debris carried by the backwash may have contributed to these dissimilar effects of land cover. For sustainable and effective coastal risk management, location of settlements is essential, while the protective potential of coastal vegetation, as determined by its spatial arrangement, should be regarded as an important livelihood provider rather than just as a bioshield. PMID:22065751

Laso Bayas, Juan Carlos; Marohn, Carsten; Dercon, Gerd; Dewi, Sonya; Piepho, Hans Peter; Joshi, Laxman; van Noordwijk, Meine; Cadisch, Georg

2011-01-01

246

The Dynamic Dielectric at a Brain Functional Site and an EM Wave Approach to Functional Brain Imaging  

PubMed Central

Functional brain imaging has tremendous applications. The existing methods for functional brain imaging include functional Magnetic Resonant Imaging (fMRI), scalp electroencephalography (EEG), implanted EEG, magnetoencephalography (MEG) and Positron Emission Tomography (PET), which have been widely and successfully applied to various brain imaging studies. To develop a new method for functional brain imaging, here we show that the dielectric at a brain functional site has a dynamic nature, varying with local neuronal activation as the permittivity of the dielectric varies with the ion concentration of the extracellular fluid surrounding neurons in activation. Therefore, the neuronal activation can be sensed by a radiofrequency (RF) electromagnetic (EM) wave propagating through the site as the phase change of the EM wave varies with the permittivity. Such a dynamic nature of the dielectric at a brain functional site provides the basis for an RF EM wave approach to detecting and imaging neuronal activation at brain functional sites, leading to an RF EM wave approach to functional brain imaging. PMID:25367217

Li, X. P.; Xia, Q.; Qu, D.; Wu, T. C.; Yang, D. G.; Hao, W. D.; Jiang, X.; Li, X. M.

2014-01-01

247

Prolate spheroidal wave functions on a disc—Integration and approximation of two-dimensional bandlimited functions  

Microsoft Academic Search

We consider the problem of integrating and approximating 2D bandlimited functions restricted to a disc by using 2D prolate spheroidal wave functions (PSWFs). We derive a numerical scheme for the evaluation of the 2D PSWFs on a disc, which is the basis for the numerical implementation of the presented quadrature and approximation schemes. Next, we derive a quadrature formula for

Yoel Shkolnisky

2007-01-01

248

The impact of ENSO on wave breaking and Southern Annular Mode events  

NASA Astrophysics Data System (ADS)

This study examines the relationship between Southern Annular Mode (SAM) events and the El Niño-Southern Oscillation (ENSO) using daily ERA-40 data. The data coverage spans the years 1979 through 2002, for the austral spring and summer seasons. The focus of this study is on the question of why positive SAM events dominate during La Niña and negative SAM events during El Niño. A composite analysis is performed on the zonal-mean zonal wind, Elliassen-Palm fluxes, and two diagnostic variables, the meridional potential vorticity gradient, a quantity that is used to estimate the likelihood of wave breaking, and a wave breaking index, which is used to evaluate the frequency of the wave breaking. On the equatorward side of the eddy-driven jet, positive SAM events are associated with strong anticyclonic wave breaking, and negative SAM events with weak anticyclonic wave breaking. On the poleward side of the eddy-driven jet, positive SAM events coincide with little wave breaking and negative SAM events by weak cyclonic wave breaking. These wave breaking events are found to occur far from the critical latitudes. With the exception of the El Nino and La Nina years, these SAM events decayed within 7 to 10 days of their establishment through mixing. The results of this investigation suggest that the background zonal-mean flow associated with La Niña (El Niño) is preconditioned for strong (weak) anticyclonic wave breaking on the equatorward side of the eddy-driven jet, the type of wave breaking that is found to drive positive (negative) SAM events. A probability density function analysis indicates that strong (weak) anticyclonic wave breaking takes place with a much higher frequency during La Niña (El Niño). It is suggested that these wave breaking characteristics, and their dependency on the background flow, can explain the strong preference for SAM events of one phase during ENSO. The analysis also showed that austral spring SAM events that coincide with ENSO are preceded by strong stratospheric SAM anomalies, and then followed by a prolonged period of wave breaking that lasts for about 30 days. These findings suggest that the ENSO background flow also plays a role in the excitation of stratospheric SAM anomalies, and that the presence of these stratospheric SAM anomalies in turn excites and then maintains the tropospheric SAM anomalies via a positive eddy feedback.

Gong, Tingting; Feldstein, Steven; Luo, Dehai

2010-05-01

249

Variation in Differential and Total Cross Sections Due to Different Radial Wave Functions  

ERIC Educational Resources Information Center

Three sets of analytical wave functions are used to calculate the Na (3s---3p) transition differential and total electron excitation cross sections by Born approximations. Results show expected large variations in values. (Author/CP)

Williamson, W., Jr.; Greene, T.

1976-01-01

250

A Study on Propagation Characteristic of One-dimensional Stress Wave in Functionally Graded Armor Composites  

NASA Astrophysics Data System (ADS)

The development of Functionally Graded Materials (FGM) for energy-absorbing applications requires understanding of stress wave propagation in these structures in order to optimize their resistance to failure. One-dimensional stress wave in FGM composites under elastic and plastic wave loading have been investigated. The stress distributions through the thickness and stress status have been analyzed and some comparisons have been done with the materials of sharp interfaces (two-layered material). The results demonstrate that the gradient structure design greatly decreases the severity of the stress concentrations at the interfaces and there are no clear differences in stress distribution in FGM composites under elastic and plastic wave loading.

Yang, S. Y.; Liu, X.; Cao, D. F.; Mei, H.; Lei, Z. T.; Liu, L. S.

2013-03-01

251

Non-convex flux functions and compound shock waves in sediment beds  

E-print Network

waves will propagate through the sediment depending on the precise form of the flux function, f(n). For soil suspensions very lit- tle is known about the form of the flux function or about the convexity or non-convexity of the function. However, detailed experimental proof of dis- continuities propagating

De Sterck, Hans

252

Linear augmented cylindrical wave Green's function method for electronic structure of nanotubes with substitutional impurities  

Microsoft Academic Search

A first-principles numerical method for calculation of the electronic structure of the point impurities in the single-walled carbon nanotubes (SWNTs) based on a Green's function technique is developed. The host SWNTs electron Green's function is calculated using a linear augmented cylindrical wave theory. The Green's function of the impurities is calculated in the terms of matrix Dyson equation. The impurities

P. N. D'Yachkov; D. Z. Kutlubaev; D. V. Makaev

2010-01-01

253

THE EVANS FUNCTION AND STABILITY CRITERIA FOR DEGENERATE VISCOUS SHOCK WAVES  

E-print Network

THE EVANS FUNCTION AND STABILITY CRITERIA FOR DEGENERATE VISCOUS SHOCK WAVES Peter Howard and Kevin of such operators was taken in the late eighties by Alexander, Gardner, and Jones, whose Evans function (generalizing earlier work of John W. Evans) serves as a characteristic function for the above

Howard, Peter

254

Efficient Computation of Prolate Spheroidal Wave Functions in Radio Astronomical Source Modeling  

Microsoft Academic Search

The application of orthonormal basis functions such as Prolate Spheroidal Wave Functions (PSWF) for accurate source modeling in radio astronomy has been comprehensively studied. They are of great importance for high fidelity, high dynamic range imaging with new radio telescopes as well as conventional ones. But the construction of PSWF is computationally expensive compared to other closed form basis functions.

Parisa Noorishad; Sarod Yatawatta

2011-01-01

255

Composite-fermion wave functions as correlators in conformal field theory  

SciTech Connect

It is known that a subset of fractional quantum Hall wave functions has been expressed as conformal field theory (CFT) correlators, notably the Laughlin wave function [Phys. Rev. Lett. 50, 1395 (1983)] at filling factor {nu}=1/m (m odd) and its quasiholes, and the Pfaffian wave function at {nu}=1/2 and its quasiholes. We develop a general scheme for constructing composite-fermion (CF) wave functions from conformal field theory. Quasiparticles at {nu}=1/m are created by inserting anyonic vertex operators, P{sub 1/m}(z), that replace a subset of the electron operators in the correlator. The one-quasiparticle wave function is identical to the corresponding CF wave function, and the two-quasiparticle wave function has correct fractional charge and statistics and is numerically almost identical to the corresponding CF wave function. We further show how to exactly represent the CF wave functions in the Jain series {nu}=s/(2sp+1) [Phys. Rev. Lett. 63, 199 (1989); Composite Fermions (Cambridge University Press, Cambridge, 2007)] as the CFT correlators of a new type of fermionic vertex operators, V{sub p,n}(z), constructed from n free compactified bosons; these operators provide the CFT representation of composite fermions carrying 2p flux quanta in the nth CF Landau level. We also construct the corresponding quasiparticle and quasihole operators and argue that they have the expected fractional charge and statistics. For filling fractions 2/5 and 3/7, we show that the chiral CFTs that describe the bulk wave functions are identical to those given by Wen's general classification [Int. J. Mod. Phys. B 6, 1711 (1992); Adv. Phys. 44, 405 (1995)] of quantum Hall states in terms of K matrices and l and t vectors, and we propose that to be generally true. Our results suggest a general procedure for constructing quasiparticle wave functions for other fractional Hall states, as well as for constructing ground states at filling fractions not contained in the principal Jain series.

Hansson, T. H. [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Chang, C.-C.; Jain, J. K. [Physics Department, 104 Davey Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Viefers, S. [Department of Physics, University of Oslo, P.O. Box 1048, Blindern, 0316 Oslo (Norway)

2007-08-15

256

Alpha-particle formation and decay rates from Skyrme-HFB wave functions  

NASA Astrophysics Data System (ADS)

? decay is treated microscopically, where the unstable mother nucleus and residual daughter nucleus are described using Hartree-Fock-Bogoliubov (HFB) wave functions, obtained with the Skyrme effective interaction. From these wave functions the amplitude for forming ? particles in the mother nucleus is computed. Two different Skyrme parametrizations with different pairing properties are compared, and we find good agreement with experiment for relative decay rates in both cases. The absolute values of the decay rates are underestimated.

Ward, D. E.; Carlsson, B. G.; Åberg, S.

2014-05-01

257

Green`s function for external excited Bohm--Gross waves  

SciTech Connect

Analytical expressions for the impulsive causal Green`s function based on the resolution of the differential equation describing the external excitation of the Bohm and Gross electrostatic wave are derived. The exact solution corresponding to the longitudinal plasma wave is put in the compact form of a two-real-variable Lommel function. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Randriamboarison, O.C.; Decreau, P.M.E. [Universite d`Orleans et Laboratoire de Physique et Chimie de l`Environnement, 45071 Orleans Cedex 2 (France)] [Universite d`Orleans et Laboratoire de Physique et Chimie de l`Environnement, 45071 Orleans Cedex 2 (France); Krasnosel`skikh, V.V. [Laboratoire de Physique et Chimie de l`Environnement, CNRS 45071 Orleans Cedex 2 (France)] [Laboratoire de Physique et Chimie de l`Environnement, CNRS 45071 Orleans Cedex 2 (France)

1995-03-01

258

Extracorporeal Shock Wave Therapy for Chronic Calcific Tendinitis of the Shoulders: A Functional and Sonographic Study  

Microsoft Academic Search

Pan P-J, Chou C-L, Chiou H-J, Ma H-L, Lee H-C, Chan R-C. Extracorporeal shock wave therapy for chronic calcific tendinitis of the shoulders: a functional and sonographic study. Arch Phys Med Rehabil 2003;84:988-93. Objectives: To evaluate the therapeutic effect of extracor- poreal shock wave therapy (ESWT) in shoulders with chronic calcific tendinitis, to compare the functional outcomes of ESWT and

Po-Jung Pan; Chen-Liang Chou; Hong-Jen Chiou; Hsiao-Li Ma; Hui-Chen Lee; Rai-Chi Chan

2003-01-01

259

An analysis of surface acoustic wave propagation in functionally graded plates with homotopy analysis method  

Microsoft Academic Search

Wave propagation in solids of functionally graded materials is difficult to analyze due to the resulting differential equations\\u000a of variable coefficients associated with the spatial variation of the material properties. In this study, the homotopy analysis\\u000a method is applied to obtain the solution of surface acoustic waves in a plate of functionally graded material. The variation\\u000a of material properties as

Liming Gao; Ji Wang; Zheng Zhong; Jianke Du

2009-01-01

260

Modelling rock-avalanche induced impact waves: Sensitivity of the model chains to model parameters  

NASA Astrophysics Data System (ADS)

New lakes are forming in high-mountain areas all over the world due to glacier recession. Often they will be located below steep, destabilized flanks and are therefore exposed to impacts from rock-/ice-avalanches. Several events worldwide are known, where an outburst flood has been triggered by such an impact. In regions such as in the European Alps or in the Cordillera Blanca in Peru, where valley bottoms are densely populated, these far-travelling, high-magnitude events can result in major disasters. Usually natural hazards are assessed as single hazardous processes, for the above mentioned reasons, however, development of assessment and reproduction methods of the hazardous process chain for the purpose of hazard map generation have to be brought forward. A combination of physical process models have already been suggested and illustrated by means of lake outburst in the Cordillera Blanca, Peru, where on April 11th 2010 an ice-avalanche of approx. 300'000m3 triggered an impact wave, which overtopped the 22m freeboard of the rock-dam for 5 meters and caused and outburst flood which travelled 23 km to the city of Carhuaz. We here present a study, where we assessed the sensitivity of the model chain from ice-avalanche and impact wave to single parameters considering rock-/ice-avalanche modeling by RAMMS and impact wave modeling by IBER. Assumptions on the initial rock-/ice-avalanche volume, calibration of the friction parameters in RAMMS and assumptions on erosion considered in RAMMS were parameters tested regarding their influence on overtopping parameters that are crucial for outburst flood modeling. Further the transformation of the RAMMS-output (flow height and flow velocities on the shoreline of the lake) into an inflow-hydrograph for IBER was also considered a possible source of uncertainties. Overtopping time, volume, and wave height as much as mean and maximum discharge were considered decisive parameters for the outburst flood modeling and were therewith assumed dependent values. The resulting 54 runs were evaluated by an ANOVA-analysis for each dependent variable. Results show, that the model chain is able to correctly reproduce the 5m-overtopping wave. Further the dependency from the input parameters could be assessed for every dependent variable. It was e.g. shown, that RAMMS-calibration has the strongest influence on all variations, it is more crucial then the uncertainties introduced by assumptions on the initial rock-avalanche volume. The study shows, that from a hazard-assessment point of view, combinations of model chains are acceptable and permissible.

Schaub, Yvonne; Huggel, Christian

2014-05-01

261

Current management of functional dyspepsia: impact of Rome III subdivision  

PubMed Central

Functional dyspepsia (FD) is a highly prevalent disease characterized by symptoms originating from the gastroduodenal region in the absence of underlying organic disease. The Rome III consensus made a distinction between meal-induced and meal-unrelated symptoms and proposed subdivision of FD into postprandial distress syndrome and epigastric pain syndrome. The applicability of this subdivision and the impact on management are areas of active research. So far, empirical approaches are still employed for the treatment of FD, although various therapeutic modalities for FD have been explored; acid-suppressive, prokinetic, and fundic relaxant drugs, antidepressants and psychological therapies. FD remains a challenge and presents unmet clinical needs. PMID:24714074

Karamanolis, Georgios P.; Tack, Jan

2012-01-01

262

EDF: Computing electron number probability distribution functions in real space from molecular wave functions  

NASA Astrophysics Data System (ADS)

Given an N-electron molecule and an exhaustive partition of the real space ( R) into m arbitrary regions ?,?,…,? ( ?i=1m?=R), the edf program computes all the probabilities P(n,n,…,n) of having exactly n electrons in ?, n electrons in ?,…, and n electrons ( n+n+⋯+n=N) in ?. Each ? may correspond to a single basin (atomic domain) or several such basins (functional group). In the later case, each atomic domain must belong to a single ?. The program can manage both single- and multi-determinant wave functions which are read in from an aimpac-like wave function description ( .wfn) file (T.A. Keith et al., The AIMPAC95 programs, http://www.chemistry.mcmaster.ca/aimpac, 1995). For multi-determinantal wave functions a generalization of the original .wfn file has been introduced. The new format is completely backwards compatible, adding to the previous structure a description of the configuration interaction (CI) coefficients and the determinants of correlated wave functions. Besides the .wfn file, edf only needs the overlap integrals over all the atomic domains between the molecular orbitals (MO). After the P(n,n,…,n) probabilities are computed, edf obtains from them several magnitudes relevant to chemical bonding theory, such as average electronic populations and localization/delocalization indices. Regarding spin, edf may be used in two ways: with or without a splitting of the P(n,n,…,n) probabilities into ? and ? spin components. Program summaryProgram title: edf Catalogue identifier: AEAJ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAJ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5387 No. of bytes in distributed program, including test data, etc.: 52 381 Distribution format: tar.gz Programming language: Fortran 77 Computer: 2.80 GHz Intel Pentium IV CPU Operating system: GNU/Linux RAM: 55 992 KB Word size: 32 bits Classification: 2.7 External routines: Netlib Nature of problem: Let us have an N-electron molecule and define an exhaustive partition of the physical space into m three-dimensional regions. The edf program computes the probabilities P(n,n,…,n)?P({n}) of all possible allocations of n electrons to ?, n electrons to ?,…, and n electrons to ?,{n} being integers. Solution method: Let us assume that the N-electron molecular wave function, ?(1,N), is a linear combination of M Slater determinants, ?(1,N)=?rMC?(1,N). Calling S?rs the overlap matrix over the 3D region ? between the (real) molecular spin-orbitals (MSO) in ?(?1r,…?Nr) and the MSOs in ?,(?1s,…,?Ns), edf finds all the P({n})'s by solving the linear system ?{n}{?kmtkn}P({n})=?r,sMCCdet[?kmtS?rs], where t=1 and t,…,t are arbitrary real numbers. Restrictions: The number of {n} sets grows very fast with m and N, so that the dimension of the linear system (1) soon becomes very large. Moreover, the computer time required to obtain the determinants in the second member of Eq. (1) scales quadratically with M. These two facts limit the applicability of the method to relatively small molecules. Unusual features: Most of the real variables are of precision real*16. Running time: 0.030, 2.010, and 0.620 seconds for Test examples 1, 2, and 3, respectively. References: [1] A. Martín Pendás, E. Francisco, M.A. Blanco, Faraday Discuss. 135 (2007) 423-438. [2] A. Martín Pendás, E. Francisco, M.A. Blanco, J. Phys. Chem. A 111 (2007) 1084-1090. [3] A. Martín Pendás, E. Francisco, M.A. Blanco, Phys. Chem. Chem. Phys. 9 (2007) 1087-1092. [4] E. Francisco, A. Martín Pendás, M.A. Blanco, J. Chem. Phys. 126 (2007) 094102. [5] A. Martín Pendás, E. Francisco, M.A. Blanco, C. Gatti, Chemistry: A European Journal 113 (2007) 9362-9371.

Francisco, E.; Pendás, A. Martín; Blanco, M. A.

2008-04-01

263

Longitudinal wave function control in single quantum dots with an applied magnetic field  

E-print Network

Controlling single-particle wave functions in single semiconductor quantum dots is in demand to implement solid-state quantum information processing and spintronics. Normally, particle wave functions can be tuned transversely by an perpendicular magnetic field. We report a longitudinal wave function control in single quantum dots with a magnetic field. For a pure InAs quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a permanent dipole oriented from base to apex. With applying magnetic field along the base-apex direction, the hole wave function shrinks in the base plane. Because of the linear changing of the confinement for hole wave function from base to apex, the center of effective mass moves up during shrinking process. Due to the uniform confine potential for electrons, the center of effective mass of electrons does not move much, which results in a permanent dipole moment change and an inverted...

Cao, Shuo; Gao, Yunan; Sun, Yue; Qiu, Kangsheng; Zhao, Yanhui; He, Min; Shi, Jin-An; Gu, Lin; Williams, David A; Sheng, Weidong; Jin, Kuijuan; Xu, Xiulai

2015-01-01

264

Wave-function formalisms in the channel coupling array theory of many-body scattering  

NASA Astrophysics Data System (ADS)

Wave-function formalisms corresponding to different channel coupling array transition operators of many-body scattering theory are derived and discussed. The Kouri-Levin transition operators are seen to be in typical Lippmann-Schwinger form and allow for the introduction of wave-function components in a particularly straightforward way. The Baer-Kouri transition operators are not in the Lippmann-Schwinger form and an alternate procedure is used to derive their corresponding wave-function components. In the three-body case, the Kouri-Levin operators T^jk obtained from the Faddeev-Lovelace choice of channel coupling array are seen to lead to precisely the Faddeev wave-function components. The Bear-Kouri operators are shown to lead to wave-function components obeying inhomogeneous equations. These inhomogeneous equations are used to give an alternate explanation of the nonunitary amplitudes obtained in recent calculations based on approximate forms of the Baer-Kouri operators. NUCLEAR REACTIONS Many-body scattering theory, channel coupling array wave-function formalisms, aspects of the bound-state type of approximation method, explanation of some nonunitary numerical results of Baer and Kouri and of Lewanski and Tobocman.

Levin, F. S.

1980-06-01

265

Analysis of Real Ship Rolling Dynamics under Wave Excitement Force Composed of Sums of Cosine Functions  

SciTech Connect

The ship motion equation with a cosine wave excitement force describes the slip moments in regular waves. A new kind of wave excitement force model, with the form as sums of cosine functions was proposed to describe ship rolling in irregular waves. Ship rolling time series were obtained by solving the ship motion equation with the fourth-order-Runger-Kutta method. These rolling time series were synthetically analyzed with methods of phase-space track, power spectrum, primary component analysis, and the largest Lyapunove exponent. Simulation results show that ship rolling presents some chaotic characteristic when the wave excitement force was applied by sums of cosine functions. The result well explains the course of ship rolling's chaotic mechanism and is useful for ship hydrodynamic study.

Zhang, Y. S. [Department of Scientific Research, Dalian Naval Academy, Dalian 116018 (China); Cai, F. [Department of Navigation, Dalian Naval Academy, Dalian 116018 (China); Xu, W. M. [Department of Hydrography and Cartography, Dalian Naval Academy, Dalian 116018 (China)

2011-09-28

266

Shock-wave-induced fracturing of calcareous nannofossils from the Chesapeake Bay impact crater  

USGS Publications Warehouse

Fractured calcareous nannofossils of the genus Discoaster from synimpact sediments within the Chesapeake Bay impact crater demonstrate that other petrographic shock indicators exist for the cratering process in addition to quartz minerals. Evidence for shock-induced taphonomy includes marginal fracturing of rosette-shaped Discoaster species into pentagonal shapes and pressure- and temperature-induced dissolution of ray tips and edges of discoasters. Rotational deformation of individual crystallites may be the mechanism that produces the fracture pattern. Shock-wave-fractured calcareous nannofossils were recovered from synimpact matrix material representing tsunami or resurge sedimentation that followed impact. Samples taken from cohesive clasts within the crater rubble show no evidence of shock-induced fracturing. The data presented here support growing evidence that microfossils can be used to determine the intensity and timing of wet-impact cratering.

Self-Trail J.M.

2003-01-01

267

Impact Of Coral Structures On Wave Directional Spreading Across A Shallow Reef Flat - Lizard Island, Northern Great Barrier Reef  

NASA Astrophysics Data System (ADS)

Coral reef hydrodynamics operate at several and overlapping spatial-temporal scales. Waves have the most important forcing function on shallow (< 5 m) reefs as they drive most ecological and biogeochemical processes by exerting direct physical stress, directly mixing water (temperature and nutrients) and transporting sediments, nutrients and plankton. Reef flats are very effective at dissipating wave energy and providing an important ecosystem service by protecting highly valued shorelines. The effectiveness of reef flats to dissipate wave energy is related to the extreme hydraulic roughness of the benthos and substrate composition. Hydraulic roughness is usually obtained empirically from frictional-dissipation calculations, as detailed field measurements of bottom roughness (e.g. chain-method or profile gauges) is a very labour and time-consuming task. In this study we measured the impact of coral structures on wave directional spreading. Field data was collected during October 2012 across a reef flat on Lizard Island, northern Great Barrier Reef. Wave surface levels were measured using an array of self-logging pressure sensors. A rapid in situ close-range photogrammetric method was used to create a high-resolution (0.5 cm) image mosaic and digital elevation model. Individual coral heads were extracted from these datasets using geo-morphometric and object-based image analysis techniques. Wave propagation was modelled using a modified version of the SWAN model which includes the measured coral structures in 2m by 1m cells across the reef. The approach followed a cylinder drag approach, neglecting skin friction and inertial components. Testing against field data included bed skin friction. Our results show, for the first time, how the variability of the reef benthos structures affects wave dissipation across a shallow reef flat. This has important implications globally for coral reefs, due to the large extent of their area occupied by reef flats, particularly, as global-scale degradation in coral reef health is causing a lowering of reef carbonate production that might lead to a decrease in reef structure and roughness.

Leon, J. X.; Baldock, T.; Callaghan, D. P.; Hoegh-guldberg, O.; Mumby, P.; Phinn, S. R.; Roelfsema, C. M.; Saunders, M. I.

2013-12-01

268

A Microcontroller-Based Instrument for Measuring P-Wave Speed in Impact-Echo Testing of Concrete  

Microsoft Academic Search

The objective of this paper is to describe a microcontroller-based instrument for measuring P-wave speed in impact-echo test of concrete. This measurement is based on measuring the travel time of the P-wave (Deltat) between two transducers at known distance apart. The present study developed an instrument to record the Deltat using interrupt-on-change feature of microcontroller and calculate the P-wave speed.

Slamet Riyadi; K. A. M. Nayan; M. M. Mustafa

2006-01-01

269

Shoreline changes and high-energy wave impacts at the leeward coast of Bonaire (Netherlands Antilles)  

NASA Astrophysics Data System (ADS)

Supralittoral coarse-clast deposits along the shores of Bonaire (Netherlands Antilles) as well as increased hurricane frequency during the past decade testify to the major hazard of high-energy wave impacts in the southern Caribbean. Since deducing certain events from the subaerial coarse-clast record involves major uncertainties and historical reports are restricted to the past 500 years, we use a new set of vibracore and push core data (i) to contribute to a more reliable Holocene history of regional extreme-wave events and (ii) to evaluate their impact on shoreline evolution. Multi-proxy palaeoenvironmental analyses (XRF, XRD, grain size distribution, carbonate, LOI, microfossils) were carried out using nearshore sedimentary archives from the sheltered western (leeward) side of Bonaire and its small neighbour Klein Bonaire. In combination with 14C-AMS age estimates the stratigraphy reflects a long-term coastal evolution controlled by relative sea level rise, longshore sediment transport, and short-term morphodynamic impulses by extreme wave action, all three of which may have significantly influenced the development of polyhaline lagoons and the demise of mangrove populations. Extreme wave events may be categorized into major episodic incidents (c. 3.6 ka [?] BP; 3.2-3.0 ka BP; 2.0-1.8 ka BP; post-1.3 ka [?] BP), which may correspond to tsunamis and periodic events recurring on the order of decades to centuries, which we interpret as severe tropical cyclones. Extreme wave events seem to control to a certain extent the formation of coastal ridges on Bonaire and, thus, to cause abrupt shifts in the long-term morphodynamic and ecological boundary conditions of the circumlittoral inland bays.

Engel, M.; Brückner, H.; Messenzehl, K.; Frenzel, P.; May, S. M.; Scheffers, A.; Scheffers, S.; Wennrich, V.; Kelletat, D.

2012-10-01

270

Coulomb wave functions with complex values of the variable and the parameters  

NASA Astrophysics Data System (ADS)

The motivation for the present paper lies in the fact that the literature concerning the Coulomb wave functions FL(?,?) and GL(?,?) is a jungle in which it may be hard to find a safe way when one needs general formulas for the Coulomb wave functions with complex values of the variable ? and the parameters L and ?. For the Coulomb wave functions and certain linear combinations of these functions we discuss the connection with the Whittaker function, the Coulomb phase shift, Wronskians, reflection formulas (L?-L-1), integral representations, series expansions, circuital relations (???e±i?) and asymptotic formulas on a Riemann surface for the variable ?. The parameters L and ? are allowed to assume complex values.

Dzieciol, Aleksander; Yngve, Staffan; Fröman, Per Olof

1999-12-01

271

FAST TRACK PAPER: Green's function retrieval from the CCF of coda waves in a scattering medium  

NASA Astrophysics Data System (ADS)

The cross-correlation function (CCF) of noises has been widely used to measure Green's function in the Earth medium. Most of theoretical works for Green's function retrieval are based on the equipartition state of random waves or the illumination by distributed stationary noise sources; however, there have been few appropriate frameworks how to retrieve Green's function from the CCF of coda waves in a scattering medium. By using the first-order Born approximation for scalar waves, we show Green's function retrieval from the CCF of coda for an impulsive spherical radiation from a point source, where the scattering medium is a random distribution of delta-function velocity anomalies in 3-D space. The CCF of single scattering coda waves at two receivers located at the opposite sides of the source is written by using Green's function in the homogenous medium. The lapse time and the time window length define the spherical shell, which is the responsible distribution of single scatterers that illuminate the receivers. The coda CCF amplitude is proportional to the inverse square of the lapse time measured from the origin time. Single scattering waves are omni-directional and equal amplitude near the source and receivers, that is, the equipartition state in the wavenumber space.

Sato, Haruo

2009-12-01

272

Climate change impact on North Sea wave conditions: a consistent analysis of ten projections  

NASA Astrophysics Data System (ADS)

Long-term changes in the mean and extreme wind wave conditions as they may occur in the course of anthropogenic climate change can influence and endanger human coastal and offshore activities. A set of ten wave climate projections derived from time slice and transient simulations of future conditions is analyzed to estimate the possible impact of anthropogenic climate change on mean and extreme wave conditions in the North Sea. This set includes different combinations of IPCC SRES emission scenarios (A2, B2, A1B, and B1), global and regional models, and initial states. A consistent approach is used to provide a more robust assessment of expected changes and uncertainties. While the spatial patterns and the magnitude of the climate change signals vary, some robust features among the ten projections emerge: mean and severe wave heights tend to increase in the eastern parts of the North Sea towards the end of the twenty-first century in nine to ten projections, but the magnitude of the increase in extreme waves varies in the order of decimeters between these projections. For the western parts of the North Sea more than half of the projections suggest a decrease in mean and extreme wave heights. Comparing the different sources of uncertainties due to models, scenarios, and initial conditions, it can be inferred that the influence of the emission scenario on the climate change signal seems to be less important. Furthermore, the transient projections show strong multi-decadal fluctuations, and changes towards the end of the twenty-first century might partly be associated with internal variability rather than with systematic changes.

Grabemann, Iris; Groll, Nikolaus; Möller, Jens; Weisse, Ralf

2014-12-01

273

Climate change impact on North Sea wave conditions: a consistent analysis of ten projections  

NASA Astrophysics Data System (ADS)

Long-term changes in the mean and extreme wind wave conditions as they may occur in the course of anthropogenic climate change can influence and endanger human coastal and offshore activities. A set of ten wave climate projections derived from time slice and transient simulations of future conditions is analyzed to estimate the possible impact of anthropogenic climate change on mean and extreme wave conditions in the North Sea. This set includes different combinations of IPCC SRES emission scenarios (A2, B2, A1B, and B1), global and regional models, and initial states. A consistent approach is used to provide a more robust assessment of expected changes and uncertainties. While the spatial patterns and the magnitude of the climate change signals vary, some robust features among the ten projections emerge: mean and severe wave heights tend to increase in the eastern parts of the North Sea towards the end of the twenty-first century in nine to ten projections, but the magnitude of the increase in extreme waves varies in the order of decimeters between these projections. For the western parts of the North Sea more than half of the projections suggest a decrease in mean and extreme wave heights. Comparing the different sources of uncertainties due to models, scenarios, and initial conditions, it can be inferred that the influence of the emission scenario on the climate change signal seems to be less important. Furthermore, the transient projections show strong multi-decadal fluctuations, and changes towards the end of the twenty-first century might partly be associated with internal variability rather than with systematic changes.

Grabemann, Iris; Groll, Nikolaus; Möller, Jens; Weisse, Ralf

2015-02-01

274

Generation of microplasma ensemble and its functional interaction with electromagnetic waves  

NASA Astrophysics Data System (ADS)

Various patterns and structures of microplasma arrays were generated, and interactions between microplasmas and electromagnetic waves were investigated both for control of waves by microplasma ensembles and for production of microplasmas by waves. Using bipolar-voltage power supply with frequencies from several kHz to several MHz and insulated wires, several types of microplasmas were generated at atmospheric pressure with their electron density ranging from 10^12 to 10^13 cm-3. They serve as equivalent dielectrics or metals according to their electron plasma frequency ranging from several GHz to several tens of GHz, with respect to the frequency of a propagating electromagnetic wave. When we installed such microplasmas forming a functional array in the propagation region of electromagnetic waves, microplasma arrays exhibited several types of performance; photonic crystals with band gaps, plasmonic waveguides, and metamaterials with extraordinary macroscopic permittivity and/or permeability. One of the significant advantages arising from use of microplasmas in a wave controller is their dynamic and tunable manner by changing external parameters such as generation power and working gas pressure. Especially rapid change of spatial generation patterns gives rise to transformation into another functional device. Another advantage is a role of complex functions arising from dispersion relations with frequency-dependent loss, which will lead to simultaneous and independent control of phase and attenuation of electromagnetic waves.

Sakai, Osamu

2008-10-01

275

Assessment of impact factors on shear wave based liver stiffness measurement.  

PubMed

Shear wave based ultrasound elastographies have been implemented as non-invasive methods for quantitative assessment of liver stiffness. Nonetheless, there are only a few studies that have investigated impact factors on liver stiffness measurement (LSM). Moreover, standard examination protocols for LSM are still lacking in clinical practice. Our study aimed to assess the impact factors on LSM to establish its standard examination protocols in clinical practice. We applied shear wave based elastography point quantification (ElastPQ) in 21 healthy individuals to determine the impact of liver location (segments I-VIII), breathing phase (end-inspiration and end-expiration), probe position (sub-costal and inter-costal position) and examiner on LSM. Additional studies in 175 healthy individuals were also performed to determine the influence of gender and age on liver stiffness. We found significant impact of liver location on LSM, while the liver segment V displayed the lowest coefficient of variation (CV 21%). The liver stiffness at the end-expiration was significantly higher than that at the end-inspiration (P=2.1E-05). The liver stiffness was 8% higher in men than in women (3.8 ± 0.7 kPa vs. 3.5 ± 0.4 kPa, P=0.0168). In contrast, the liver stiffness was comparable in the different probe positions, examiners and age groups (P>0.05). In conclusion, this study reveals significant impact from liver location, breathing phase and gender on LSM, while furthermore strengthening the necessity for the development of standard examination protocols on LSM. PMID:23116805

Ling, Wenwu; Lu, Qiang; Quan, Jierong; Ma, Lin; Luo, Yan

2013-02-01

276

Comparative study of different SPH schemes on simulating violent water wave impact flows  

NASA Astrophysics Data System (ADS)

Free surface flows are of significant interest in Computational Fluid Dynamics (CFD). However, violent water wave impact simulation especially when free surface breaks or impacts on solid wall can be a big challenge for many CFD techniques. Smoothed Particle Hydrodynamics (SPH) has been reported as a robust and reliable method for simulating violent free surface flows. Weakly compressible SPH (WCSPH) uses an equation of state with a large sound speed, and the results of the WCSPH can induce a noisy pressure field and spurious oscillation of pressure in time history for wave impact problem simulation. As a remedy, the truly incompressible SPH (ISPH) technique was introduced, which uses a pressure Poisson equation to calculate the pressure. Although the pressure distribution in the whole field obtained by ISPH is smooth, the stability of the techniques is still an open discussion. In this paper, a new free surface identification scheme and solid boundary handling method are introduced to improve the accuracy of ISPH. This modified ISPH is used to study dam breaking flow and violent tank sloshing flows. On the comparative study of WCSPH and ISPH, the accuracy and efficiency are assessed and the results are compared with the experimental data.

Zheng, Xing; Ma, Qing-wei; Duan, Wen-yang

2014-12-01

277

Submillimeter Wave Astronomy Satellite observations of comet 9P/Tempel 1 and Deep Impact  

E-print Network

On 4 July 2005 at 5:52 UT the Deep Impact mission successfully completed its goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on the nucleus and ejecting material into the coma of the comet. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the 1(10)-1(01) ortho-water ground-state rotational transition in comet 9P/Tempel 1 before, during, and after the impact. No excess emission from the impact was detected by SWAS and we derive an upper limit of 1.8e7 kg on the water ice evaporated by the impact. However, the water production rate of the comet showed large natural variations of more than a factor of three during the weeks before and after the impact. Episodes of increased activity with Q(H2O)~1e28 molecule/s alternated with periods with low outgassing (Q(H2O)comet rotates. We calculate that appreciable asymmetries of these features could lead to a spin-down or spin-up of the nucleus at observable rates.

F. Bensch; G. J. Melnick; D. A. Neufeld; M. Harwit; R. L. Snell; B. M. Patten; V. Tolls

2006-06-02

278

Endothelium function assessment with radial pulse wave signals  

Microsoft Academic Search

This study proposes a method of measuring vasodilatation via air pressure sensing to assess the function of endothelium cells. The vasodilatation index is calculated according to the change of area of waveform caused by stimulation to the blood vessels, and uses this index to reflect the function of endothelium cells; therefore, early self-monitoring of cardiovascular dysfunction and arterial stiffness can

Hsien-Tsai Wu; Chun-Ho Lee; Tsang-Chin Wu; An-Bang Liu

2009-01-01

279

Dissipation of Magnetohydrodynamic Waves on Energetic Particles: Impact on Interstellar Turbulence and Cosmic Ray Transport  

SciTech Connect

The physical processes involved in diffusion of Galactic cosmic rays in the interstellar medium are addressed. We study the possibility that the nonlinear MHD cascade sets the power-law spectrum of turbulence which scatters charged energetic particles. We find that the dissipation of waves due to the resonant interaction with cosmic ray particles may terminate the Kraichnan-type cascade below wavelengths 10{sup 13} cm. The effect of this wave dissipation has been incorporated in the GALPROP numerical propagation code in order to asses the impact on measurable astrophysical data. The energy-dependence of the cosmic-ray diffusion coefficient found in the resulting self-consistent model may explain the peaks in the secondary to primary nuclei ratios observed at about 1 GeV/nucleon.

Ptuskin, V.S.; /Troitsk, IZMIRAN /Maryland U.; Moskalenko, Igor V.; /Stanford U., HEPL; Jones, F.C.; /NASA, Goddard; Strong, A.W.; /Garching, Max Planck Inst., MPE; Zirakashvili, V.N.; /Troitsk, IZMIRAN /Heidelberg, Max Planck Inst. Astron.

2006-01-17

280

Wave Propagation Analysis of Edge Cracked Circular Beams under Impact Force  

PubMed Central

This paper presents responses of an edge circular cantilever beam under the effect of an impact force. The beam is excited by a transverse triangular force impulse modulated by a harmonic motion. The Kelvin–Voigt model for the material of the beam is used. The cracked beam is modelled as an assembly of two sub-beams connected through a massless elastic rotational spring. The considered problem is investigated within the Bernoulli-Euler beam theory by using energy based finite element method. The system of equations of motion is derived by using Lagrange's equations. The obtained system of linear differential equations is reduced to a linear algebraic equation system and solved in the time domain by using Newmark average acceleration method. In the study, the effects of the location of crack, the depth of the crack, on the characteristics of the reflected waves are investigated in detail. Also, the positions of the cracks are calculated by using reflected waves. PMID:24972050

Akba?, ?eref Do?u?can

2014-01-01

281

The impact of alcohol dependence on social brain function.  

PubMed

The impact of alcoholism (ALC) or alcohol dependence on the neural mechanisms underlying cognitive and affective empathy (i.e. the different routes to understanding other people's minds) in schizophrenic patients and non-schizophrenic subjects is still poorly understood. We therefore aimed at determining the extent to which the ability to infer other people's mental states and underlying neural mechanisms were affected by ALC. We examined 48 men, who suffered either from ALC, schizophrenia, both disorders or none of these disorders, using functional magnetic resonance imaging while performing on a mind reading task that involves both cognitive and affective aspects of empathy. Using voxel-based morphometry, we additionally examined whether between-group differences in functional activity were associated with deficits in brain structural integrity. During mental state attribution, all clinical groups as compared with healthy controls exhibited poor performance as well as reduced right-hemispheric insular function with the highest error rate and insular dysfunction seen in the schizophrenic patients without ALC. Accordingly, both behavioral performance and insular functioning revealed schizophrenia × ALC interaction effects. In addition, schizophrenic patients relative to non-schizophrenic subjects (regardless of ALC) exhibited deficits in structural integrity and task-related recruitment of the left ventrolateral prefrontal cortex (vlPFC). Our data suggest that ALC-related impairment in the ability to infer other people's mental states is limited to insular dysfunction and thus deficits in affective empathy. By contrast, mentalizing in schizophrenia (regardless of ALC) may be associated with insular dysfunction as well as a combination of structural and functional deficits in the left vlPFC. PMID:22340281

Gizewski, Elke R; Müller, Bernhard W; Scherbaum, Norbert; Lieb, Bodo; Forsting, Michael; Wiltfang, Jens; Leygraf, Norbert; Schiffer, Boris

2013-01-01

282

Optical Transfer Function of Concave Grating Spectrometer Based on Wave Optical Method  

Microsoft Academic Search

Optical transfer functions (OTF) of two types of spectrometer --- Eagle mounting and Seya-Namioka mounting --- are calculated by the wave-optical method which defines the OTF as the autocorrelation function of the pupil. Results obtained are compared with previous results of the present authors and interpreted as effects of diffraction and aberration on the broadening of point image. The OTFs

Tsuneo Katayama; Akio Takahashi

1970-01-01

283

Localization of multiphoton ionization\\/dissociation resonance wave functions in AC fields  

Microsoft Academic Search

Although it has been proved before J. Chem. Phys. 101, 9716 1995 that the complex scaled photoionizingrphotodissociating resonances are associated with square integrable functions only when the time-dependent Hamiltonian is represented . in the velocity or acceleration gauges , it is proved here that in the length gauge a narrow . resonance wave function and not a broad one! may

Nimrod Moiseyev

1997-01-01

284

Computation and performance of the prolate-spheroidal wave function window in spectral estimation  

Microsoft Academic Search

It has been proven that the prolate-spheroidal wave function (PSWF) window is the optimal high-resolution window in the classical spectral estimation. However, the implementation of the PSWF window is difficult in the past due to the lack of a closed form solution. The numerical computation of the PSWF window using the Legendre function is considered and the performance of this

Zhiyue Lin; Richard W McCallum; Hongyu Wang

1996-01-01

285

Multi-domain decomposition method for real-time propagation of wave function  

NASA Astrophysics Data System (ADS)

Extension of electronic structure methods to ever-large systems is an important problem in computational material and bio sciences. We have developed a time-dependent density functional approach that is capable to describe electron dynamics in large molecular complexes and realistic nanostructures. For wave function propagation, the most expensive numeric operation is the evaluation of product of Hamiltonian matrix and wave function. We use a multi-domain decomposition to increase numerical efficiency of this operation that results in efficient real time propagation of wave function in real space. We currently perform extensive testing of the new system and plan to use it in calculations of optical absorption spectra of supra-molecular assemblies. Results will be presented for C60-Fe-porphyrin complex.

Goncharov, Vladimir; Varga, Kalman

2010-03-01

286

Basis of symmetric polynomials for many-boson light-front wave functions  

NASA Astrophysics Data System (ADS)

We provide an algorithm for the construction of orthonormal multivariate polynomials that are symmetric with respect to the interchange of any two coordinates on the unit hypercube and are constrained to the hyperplane where the sum of the coordinates is one. These polynomials form a basis for the expansion of bosonic light-front momentum-space wave functions, as functions of longitudinal momentum, where momentum conservation guarantees that the fractions are on the interval [0 ,1 ] and sum to one. This generalizes earlier work on three-boson wave functions to wave functions for arbitrarily many identical bosons. A simple application in two-dimensional ?4 theory illustrates the use of these polynomials.

Chabysheva, Sophia S.; Hiller, John R.

2014-12-01

287

Covariant spectator theory of np scattering: Effective range expansions and relativistic deuteron wave functions  

SciTech Connect

We present the effective range expansions for the {sup 1}S{sub 0} and {sup 3}S{sub 1} scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with {chi}{sup 2}/N{sub data{approx_equal}}1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A fortran subroutine to compute these wave functions can be obtained from the authors.

Gross, Franz; Stadler, Alfred [College of William and Mary, Williamsburg, Virginia 23185 (United States) and Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Centro de Fisica Nuclear da Universidade de Lisboa, P-1649-003 Lisboa (Portugal) and Departamento de Fisica da Universidade de Evora, P-7000-671 Evora (Portugal)

2010-09-15

288

Performance of storm damage functions: a sectoral impact model intercomparison  

NASA Astrophysics Data System (ADS)

Winter storms are the most costly natural hazard for European residential property. We compare four distinct storm damage functions with respect to their forecast accuracy and variability, with particular regard to the most severe winter storms. The analysis focuses on daily loss estimates under differing spatial aggregation, ranging from district to country level. We discuss the broad and heavily skewed distribution of insured losses posing difficulties on both the calibration and the evaluation of damage functions. From theoretical considerations, we provide a synthesis between the frequently discussed cubic damage-wind relationship and recent studies that report much steeper damage functions for European winter storms. The performance of the storm loss models is evaluated for two wind data sources, direct observation by the German Weather Service and ERA Interim reanalysis data. While the choice of wind data indicates little impact for the evaluation of German storm loss, local variability exhibits dependence between model and data choices. Based on our analysis, we favour the application of two probabilistic approaches which fare best in terms of the accuracy of their expected value and overall exhibit the lowest amount of variability.

Prahl, B. F.; Rybski, D.; Burghoff, O.; Kropp, J. P.

2014-09-01

289

Impact of common KIBRA allele on human cognitive functions.  

PubMed

The rs17070145 polymorphism (C ? T substitution, intron 9) of the KIBRA gene has recently been associated with episodic memory and cognitive flexibility. These findings were inconsistent across reports though, and largely lacked gene-gene or gene-environment interactions. The aim of the present study was to determine the impact of the rs17070145 polymorphism on clinically relevant cognitive domains and its interaction with the modifiers 'lifestyle' and 'cardiovascular risk factors'. Five-hundred forty-five elderly volunteers (mean age 64 years, ±7 years, 56% women) accomplished a comprehensive cognitive testing. Principal component analysis was used to reveal the internal structure of the data, rendering four composite scores: verbal memory, word fluency, executive function/psychomotor speed, and working memory. Lifestyle was assessed with a detailed questionnaire, age-associated risk factors by clinical interview and examination. There was no main effect of the rs17070145 genotype on any cognitive composite scores. However, we found worse performance in executive functions for T-allele carriers in the presence of arterial hypertension (?=-0.365, p=0.0077 and 0.031 after Bonferroni correction). This association was further modified by gender, showing the strongest association in hypertensive females (?=-0.500, p=0.0072 and 0.029 after Bonferroni correction). The effect of KIBRA on cognitive function seems to be complex and modified by gender and arterial hypertension. PMID:21346737

Wersching, H; Guske, K; Hasenkamp, S; Hagedorn, C; Schiwek, S; Jansen, S; Witte, V; Wellmann, J; Lohmann, H; Duning, K; Kremerskothen, J; Knecht, S; Brand, E; Floel, A

2011-05-01

290

Impact of gynecological surgery on female sexual function.  

PubMed

Sexual function is complex and involves interaction of many factors, including emotional connection, body image, intact physical response and partner sexual function. Disease processes such as abnormal uterine bleeding, endometriosis, urinary incontinence and pelvic organ prolapse may have a negative impact on various parameters of sexual health. Gynecological surgery to address these common complaints may correct the pathological process. However, despite improvements in symptoms related to the disease, improvements in sexuality are not guaranteed and occasionally there may be deteriorations. This review will summarize the current literature assessing sexual symptoms following benign gynecological surgery, including hysterectomy, and bilateral salpingo-oophorectomy, tubal ligation, anti-incontinence surgery and pelvic organ prolapse reconstruction with and without mesh. In the majority of cases, sexual function and quality of life benefit from these surgical interventions. However, it is critical that physicians remain aware of the potential for negative outcomes. Subjects who experience worsening should undergo thorough evaluation early in the postoperative period in order to mitigate symptoms. Treatment modalities for sexual dysfunction following surgery should be the focus of future research. PMID:20072131

Pauls, R N

2010-01-01

291

Mathieu function solutions for photoacoustic waves in sinusoidal one-dimensional structures  

NASA Astrophysics Data System (ADS)

The photoacoustic effect for a one-dimensional structure, the sound speed of which varies sinusoidally in space, is shown to be governed by an inhomogeneous Mathieu equation with the forcing term dependent on the spatial and temporal properties of the exciting optical radiation. New orthogonality relations, traveling wave Mathieu functions, and solutions to the inhomogeneous Mathieu equation are found, which are used to determine the character of photoacoustic waves in infinite and finite length phononic structures. Floquet solutions to the Mathieu equation give the positions of the band gaps, the damping of the acoustic waves within the band gaps, and the dispersion relation for photoacoustic waves. The solutions to the Mathieu equation give the photoacoustic response of the structure, show the space equivalent of subharmonic generation and acoustic confinement when waves are excited within band gaps.

Wu, Binbin; Diebold, Gerald J.

2012-07-01

292

Mathieu function solutions for photoacoustic waves in sinusoidal one-dimensional structures.  

PubMed

The photoacoustic effect for a one-dimensional structure, the sound speed of which varies sinusoidally in space, is shown to be governed by an inhomogeneous Mathieu equation with the forcing term dependent on the spatial and temporal properties of the exciting optical radiation. New orthogonality relations, traveling wave Mathieu functions, and solutions to the inhomogeneous Mathieu equation are found, which are used to determine the character of photoacoustic waves in infinite and finite length phononic structures. Floquet solutions to the Mathieu equation give the positions of the band gaps, the damping of the acoustic waves within the band gaps, and the dispersion relation for photoacoustic waves. The solutions to the Mathieu equation give the photoacoustic response of the structure, show the space equivalent of subharmonic generation and acoustic confinement when waves are excited within band gaps. PMID:23005556

Wu, Binbin; Diebold, Gerald J

2012-07-01

293

The Impact of Heat Islands on Mortality in Paris during the August 2003 Heat Wave  

PubMed Central

Background: Heat waves have a drastic impact on urban populations, which could increase with climate change. Objectives: We evaluated new indicators of elderly people’s exposure to heat in Paris, from a public health prevention perspective, using satellite thermal images. Methods: We used a time series of 61 images from the satellites of the National Oceanic and Atmospheric Administration’s (NOAA) Advanced Very High Resolution Radiometer (AVHRR) taken from 1 to 13 August 2003 to produce thermal indicators of minimum, maximum, and mean surface temperatures and diurnal temperature amplitude, with different lags between the meteorological data and the health impact. Health data came from a case–control study involving 241 people ? 65 years of age who died in the city of Paris or the nearby suburban area of Val-de-Marne during the August 2003 heat wave, and 241 controls who were matched to cases on age, sex, and residential zone. For each person, we integrated the thermal indicators in a conditional logistic regression model, adjusted for age and other potential confounders. We computed odds ratios (ORs) comparing the 90th and 50th percentiles of the temperature differences between cases and controls for various indicators. Results: Mortality risk was significantly associated with exposure for two indicators: minimum temperatures averaged for 1–13 August [for a 0.41°C increase, OR = 2.17; 95% confidence interval (CI): 1.14, 4.16] and minimum temperature averaged on the day of death and the 6 preceding days (for a 0.51°C increase: OR = 2.24; 95% CI: 1.03, 4.87). Conclusions: Our results support the influence of night temperatures on the health impact of heat waves in urban areas. Urban heat exposure indicators based on satellite imagery have the potential to identify areas with higher risk of death, which could inform intervention decisions by key stakeholders. PMID:21885383

Zeghnoun, Abdelkrim; Dousset, Bénédicte; Bretin, Philippe; Vandentorren, Stéphanie; Giraudet, Emmanuel; Beaudeau, Pascal

2011-01-01

294

Impacts of Oxidative Stress and Antioxidants on Semen Functions  

PubMed Central

Oxidative stress (OS) has been considered a major contributory factor to the infertility. Oxidative stress is the result of imbalance between the reactive oxygen species (ROS) and antioxidants in the body which can lead to sperm damage, deformity, and eventually male infertility. Although high concentrations of the ROS cause sperm pathology (ATP depletion) leading to insufficient axonemal phosphorylation, lipid peroxidation, and loss of motility and viability but, many evidences demonstrate that low and controlled concentrations of these ROS play an important role in sperm physiological processes such as capacitation, acrosome reaction, and signaling processes to ensure fertilization. The supplementation of a cryopreservation extender with antioxidant has been shown to provide a cryoprotective effect on mammalian sperm quality. This paper reviews the impacts of oxidative stress and reactive oxygen species on spermatozoa functions, causes of ROS generation, and antioxidative strategies to reduce OS. In addition, we also highlight the emerging concept of utilizing OS as a tool of contraception. PMID:20871827

Bansal, Amrit Kaur; Bilaspuri, G. S.

2011-01-01

295

P wave bottomonium spectral functions in the QGP from lattice NRQCD  

E-print Network

We present an overview of bottomonium spectral functions in the quark-gluon plasma, obtained by the FASTSUM collaboration, using lattice QCD simulations with two light quark flavours on anisotropic lattices. The bottom quark is treated nonrelativistically. While we find that the S wave ground states survive up to the highest temperature we consider, we have strong indications that P wave states melt immediately above Tc.

Gert Aarts; Chris Allton; Seyong Kim; Maria-Paola Lombardo; Sinead M. Ryan; Jon-Ivar Skullerud

2013-11-05

296

Finasteride-its impact on sexual function and prostate cancer.  

PubMed

Finasteride, a specific and competitive inhibitor of 5alpha-reductase enzyme Type 2, inhibits the conversion of testosterone to dihydrotestosterone (DHT). In adults, DHT acts as primary androgen in prostate and hair follicles. The only FDA-approved dermatological indication of finasteride is androgenetic alopecia. But, apprehension regarding sexual dysfunction associated with finasteride deters dermatologists from prescribing the drug and patients from taking the drug for androgenetic alopecia. Testosterone, through its humoral endocrine and local paracrine effects is relevant in central and peripheral modulation of sexual function than locally acting DHT. Several large population-based long-term placebo-controlled studies, using International Index of Erectile Function-5 questionnaire and objective method (Nocturnal Penile Tumescence) to assess the erectile function have demonstrated no clear evidence of the negative effect of finasteride on erectile function. Reduction in ejaculatory volume is the only established causal relationship between finasteride and sexual dysfunction. Though finasteride causes significant reduction in all the semen parameters except sperm morphology, they did not fall below the threshold levels to interfere with fertility. Therefore, the sexual adverse effects associated with finasteride should be viewed in relation to normal prevalence and natural history of erectile dysfunction in the population, age of the patient, other confounding factors and also nocebo effect. The impact of finasteride on the prevention of prostate cancer has been discussed extensively. Finasteride is found to be effective in significantly reducing the incidence of low-grade prostate cancer. But the paradoxical increase in high-grade cancer in the finasteride group has been attributed to increased sensitivity and improved performance of prostate specific antigen levels to detect all grades of prostate cancer. PMID:20300365

Anitha, B; Inamadar, Arun C; Ragunatha, S

2009-01-01

297

Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.  

PubMed

We invented a triboelectric nanogenerator (TENG) that is based on a wavy-structured Cu-Kapton-Cu film sandwiched between two flat nanostructured PTFE films for harvesting energy due to mechanical vibration/impacting/compressing using the triboelectrification effect. This structure design allows the TENG to be self-restorable after impact without the use of extra springs and converts direct impact into lateral sliding, which is proved to be a much more efficient friction mode for energy harvesting. The working mechanism has been elaborated using the capacitor model and finite-element simulation. Vibrational energy from 5 to 500 Hz has been harvested, and the generator's resonance frequency was determined to be ?100 Hz at a broad full width at half-maximum of over 100 Hz, producing an open-circuit voltage of up to 72 V, a short-circuit current of up to 32 ?A, and a peak power density of 0.4 W/m(2). Most importantly, the wavy structure of the TENG can be easily packaged for harvesting the impact energy from water waves, clearly establishing the principle for ocean wave energy harvesting. Considering the advantages of TENGs, such as cost-effectiveness, light weight, and easy scalability, this approach might open the possibility for obtaining green and sustainable energy from the ocean using nanostructured materials. Lastly, different ways of agitating water were studied to trigger the packaged TENG. By analyzing the output signals and their corresponding fast Fourier transform spectra, three ways of agitation were evidently distinguished from each other, demonstrating the potential of the TENG for hydrological analysis. PMID:24964297

Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin

2014-07-22

298

Symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization  

SciTech Connect

The symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization are investigated. It is shown that the square modulus of the scattering matrix element in which the spin states of all four electrons are determined is not invariant under the reversal of the direction of alignment of all spins. The largest of two contributions to this noninvariance originates from the relativistic modifications of the continuum wave functions induced by the distorting potential of the target atom. A second smaller contribution is manifested on reducing the eight-dimensional matrix elements of the QED covariant propagator to purely spatial two-electron integrals. The triple differential cross section (TDCS) exhibits a spin asymmetry unless the entire scattering process occurs in a single plane. There will be a difference in the TDCS between an (e,2e) event in which the initial beam is polarized parallel or antiparallel with respect to the beam direction even if the target is unpolarized and the final spin states are not determined. The TDCS will remain unchanged if, in addition to reversal of the direction of spin alignment, one appropriate momentum component of one of the two outgoing electrons is reversed.

Pyper, N. C.; Kampp, Marco; Whelan, Colm T. [University Chemical Laboratory, Lensfield Road, Cambridge, CB2 1EW (United Kingdom); Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW (United Kingdom); Department of Physics, Old Dominion University, Norfolk, Virginia 23529-0116 (United States)

2005-05-15

299

Equality of Bulk Wave Functions and Edge Correlations in Some Topological Superconductors: A Spacetime Derivation  

Microsoft Academic Search

For certain systems, the N-particle ground-state wave functions of the bulk happen to be exactly equal to the N-point spacetime correlation functions at the edge, in the infrared limit. We show why this had to be so for a class of topological superconductors, beginning with the p+ip state in D=2+1. Varying the chemical potential as a function of Euclidean time

R. Shankar; Ashvin Vishwanath

2011-01-01

300

Kinetic correlation in the final-state wave function in photo-double-ionization of He  

SciTech Connect

We evaluate the triply differential cross section (TDCS) for photo-double-ionization of helium. We use a final continuum wave function which correlates the motion of the three particles, through an expansion in products of two-body Coulomb functions. This function satisfies a set of appropriate physical conditions in the coalescence points, in addition to the correct asymptotic behavior condition. We analyze the effect of this correlation in the TDCS and compare our results with experimental data.

Otranto, S. [CONICET and Centro Atomico Bariloche, 8400 San Carlos de Bariloche, (Argentina); Departamento de Fisica, Universidad Nacional del Sur, 8000 Bahia Blanca, (Argentina); Garibotti, C. R. [CONICET and Centro Atomico Bariloche, 8400 San Carlos de Bariloche, (Argentina)

2003-06-01

301

Uniform Estimates of the Prolate Spheroidal Wave Functions and Spectral Approximation in Sobolev Spaces  

Microsoft Academic Search

For fixed c, Prolate Spheroidal Wave Functions $\\\\psi_{n, c}$ form a basis with remarkable properties for the space of band-limited functions with bandwith $c$. They have been largely studied and used after the seminal work of Slepian. Recently, they have been used for the approximation of functions of the Sobolev space $H^s([-1,1])$. The choice of $c$ is then a central

Aline Bonami; Abderrazek Karoui

2010-01-01

302

U (1 )×U (1 ) symmetry-protected topological order in Gutzwiller wave functions  

NASA Astrophysics Data System (ADS)

Gutzwiller projection is a way to construct many-body wave functions that could carry topological order or symmetry-protected topological (SPT) order. However, an important issue is to determine whether or not a given Gutzwiller-projected wave function (GWF) carries a nontrivial SPT order, and which SPT order is carried by the wave function. In this paper, we numerically study the SPT order in a spin S =1 GWF on the kagome lattice. Using the standard Monte Carlo method, we directly confirm that the GWF has (1) gapped bulk with short-range correlations, (2) a trivial topological order via a nondegenerate ground state, and zero topological entanglement entropy, (3) a nontrivial U (1 )×U (1 ) SPT order via the Hall conductances of the protecting U (1 )×U (1 ) symmetry, and (4) a symmetry-protected gapless boundary. This represents numerical evidence of continuous symmetry-protected topological order in two-dimensional bosonic lattice systems.

Liu, Zheng-Xin; Mei, Jia-Wei; Ye, Peng; Wen, Xiao-Gang

2014-12-01

303

Two Wave Functions and dS/CFT on S^1 x S^2  

E-print Network

We evaluate the tunneling and Hartle-Hawking wave functions on S^1 x S^2 boundaries in Einstein gravity with a positive cosmological constant. In the large overall volume limit the classical predictions of both wave functions include an ensemble of Schwarzschild-de Sitter black holes. We show that the Hartle-Hawking tree level measure on the classical ensemble converges in the small S 1 limit. A divergence in this regime can be identified in the tunneling state. However we trace this to the contribution of an unphysical branch of saddle points associated with negative mass black holes. Using a representation in which all saddle points have an interior Euclidean anti-de Sitter region we also generalise the holographic formulation of the semiclassical Hartle-Hawking wave function to S^1 x S^2 boundaries.

Conti, Gabriele

2014-01-01

304

Quantization of the canonical tensor model and an exact wave function  

NASA Astrophysics Data System (ADS)

Tensor models in various forms are being studied as models of quantum gravity. Among them the canonical tensor model has a canonical pair of rank-three tensors as dynamical variables, and is a pure constraint system with first-class constraints. The Poisson algebra of the first-class constraints provides an algebraically consistent way of discretizing the Dirac algebra for general relativity. This paper successfully formulates the Wheeler-DeWitt quantization of the canonical tensor model. Formally one can obtain wave functions of the "universe" by solving the partial differential equations representing the constraints. For the simplest non-trivial case, the unique wave function is exactly and globally obtained. Although this case is far from being realistic, the wave function is physically interesting; locality is favored, and there exists a locus of configurations with features of the beginning of the universe.

Sasakura, Naoki

2014-03-01

305

Wave functions of $SU(3)$ pure gauge glueballs on the lattice  

E-print Network

The Bethe-Salpeter wave functions of $SU(3)$ pure gauge glueballs are revisited in this study. The ground and the first excited states of scalar and tensor glueballs are identified unambiguously by using the variational method on the basis of large operator sets. We calculate their wave functions in the Coulomb gauge and use two lattices with different lattice spacings to check the discretization artifacts. For ground states, the radial wave functions are approximately Gaussian and the size of the tensor is twice as large as that of the scalar. For the first excited states, the radial nodes are clearly observed for both the scalar and the tensor glueballs, such that they can be interpreted as the first radial excitations. These observations may shed light on the theoretical understanding of the inner structure of glueballs.

Jian Liang; Ying Chen; Wei-Feng Chiu; Long-Cheng Gui; Ming Gong; Zhaofeng Liu

2014-11-09

306

Current state of acoustic wave propagation modelling and its use in the estimation of impact on marine mammals  

NASA Astrophysics Data System (ADS)

Underwater acoustic wave propagation modelling has matured into a sophisticated and reliable forecasting tool for predicting the acoustic noise footprints of geophysical exploration activities. Computational methods such as Parabolic Equation solutions of the wave function can account for all aspects of acoustic propagation including diffraction, mode stripping, and compressional and shear wave transmission in the seabed substrate. Given sufficient knowledge of the acousto-physical properties of the water column and the seabed, it is possible to estimate the acoustic transmission loss for individual sound frequencies and hence the overall attenuation of a spectrally described source at any range. In combination with numerical models that provide reliable estimates of the acoustic pulse properties and spatial pattern of the sound emission from any design of airgun array, wave propagation modelling provides the means to fully characterize the ensonification of an area without need for experimental measurement, allowing the potential impact on the marine environment of a planned operation to be studied in advance of physical deployment of the equipment. In this presentation we provide an overview of the current state of acoustic propagation modelling methods with particular emphasis on full noise footprint estimation, whereby the acoustic propagation model is automatically run along multiple traverses to cover the region of interest to a desired spatial resolution. The prediction of sound level footprints, however, is only a step in the process of estimating the acoustic impact on sea life and especially marine mammals. The interaction between the sound and the subject is also influenced by the subject's frequency-dependent auditory sensitivity relative to the frequency content of the sounds to which it is exposed. Much experimental work has been performed recently to measure frequency- dependent auditory thresholds (audiograms) for many marine mammal species. The degree to which sounds are audible to a subject can be quantified by subtracting the audiogram thresholds, in decibels, from the respective frequency-dependent band levels of the sounds prior to summing the band levels. This approach is exactly analogous to the use of frequency weighting schemes commonly employed for assessment of noise impact on humans. The degree of impact is also dependent on the behavioural response to the detected noise. The process may be modelled in a static fashion whereby the statistical distribution density of a certain species in an area is intersected with the acoustic footprint of an operation at a given reaction threshold level to yield the number of subjects that can be potentially affected. Another modelling approach considers instead a dynamic scenario of the population, whereby subjects are probabilistically positioned in the region of interest and the modelled acoustic field is mapped at each subject location. In this approach the behavioural reaction of the subject, such as avoidance of sounds above a certain level, is also taken into account. Here we review some prominent approaches to sound-subject interaction modelling and discuss their merits and weaknesses, the assumptions on which they rely, and where future developments may lead in the numerical estimation of the acoustic impact of a geophysical operation on a species.

Racca, R.; Hannay, D.; Carr, S.

2006-05-01

307

Development of a shock wave adhesion test for composite bonds by pulsed laser and mechanical impacts  

NASA Astrophysics Data System (ADS)

Evaluating the bonding quality of composite material is becoming one of the main challenges faced by aeronautic industries. This work aims to the development of a technique using shock wave, which would enable to quantify the bonding mechanical quality. Laser shock experiments were carried out. This technique enables high tensile stress generation in the thickness of composite bonds. The resulting damage has been quantified using different methods such as confocal microscopy, ultrasound and cross section observation. The discrimination between a correct bond and a weak bond was possible thanks to these experiments. Nevertheless, laser sources are not well adapted for optimization of such a test because of often fixed settings. That is why mechanical impacts on bonded composites were also performed in this work. By changing the thickness of aluminum projectiles, the generated tensile stresses by the shock wave propagation were moved toward the composite/bond interface. The made observations prove that the technique optimization is possible. The key parameters for the development of a bonding test using shock waves have been identified.

Ecault, R.; Boustie, M.; Touchard, F.; Arrigoni, M.; Berthe, L.

2014-05-01

308

The seismic response of an aquifer to the propagation of an impact generated shock wave: A possible trigger of the Martian outflow channels?  

NASA Technical Reports Server (NTRS)

Aquifer dilation from shock waves produced by the 8.4 magnitude Alaskan earthquake of 1964 led to water and sediment ejection from the ground up to 400 km away from the earthquake's epicenter. Groundwater disturbances were observed as far away as Perry, Florida (approximately 5500 km), where well water fluctuations with an amplitude of as much as 2.3 m were reported. The martian cratering record provides evidence that the planet has experienced numerous seismic events of a similar, and often much greater, magnitude. Given this fact, and the photogeologic evidence for abundant water in the early crust, the response of a basalt aquifer to the propagation of compressional waves (P-waves) produced by impacts in the 33-1000 km diameter size range were investigated. The resulting one-dimensional changes in effective stress and pore pressure were calculated - as a function of both distance and time - based on the following assumptions: (1) that all of the seismic energy radiated by an impact is transmitted as a single compressional wave; (2) that both the host rock and groundwater are compressible; and (3) that there is no net flow between the water-filled pores.

Leyva, Ivett A.; Clifford, Stephen M.

1993-01-01

309

Basis functions for solution of non-homogeneous wave equation  

NASA Astrophysics Data System (ADS)

In this note we extend the Differential Transfer Matrix Method (DTMM) for a second-order linear ordinary differential equation to the complex plane. This is achieved by separation of real and imaginary parts, and then forming a system of equations having a rank twice the size of the real-valued problem. The method discussed in this paper also successfully removes the problem of dealing with essential singularities, which was present in the earlier formulations. Then we simplify the result for real-valued problems and obtain a new set of basis functions, which may be used instead of the WKB solutions. These basis functions not only satisfy the initial conditions perfectly, but also, may approach the turning points without the divergent behavior, which is observed in WKB solutions. Finally, an analytical transformation in the form of a matrix exponential is presented for improving the accuracy of solutions.

Khorasani, Sina; Karimi, Farhad

2013-03-01

310

Impact of Anthropogenic Land Cover Change on Heat Waves : the summer 2003 as a testbed.  

NASA Astrophysics Data System (ADS)

In this study we investigate the two-way interactions of vegetation and climate on regional scales. a comparison is performed to assess the impact for the anomalous year 2003 of a potential vegetation distribution where human influence is suppressed to a simulation with a current vegetation distribution via a modelling approach. Main processes which contribute to these differences are analysed. Both simulations are performed with the help of the modelling platform MORCE which comprises a coupled version of the atmospheric model WRF and the dynamic vegetation model ORCHIDEE. The first run was conducted using a potential vegetation map, the second used a current vegetation map. The simulation domain in the Mediterranean region has been chosen for its important climate sensitivity to surface conditions in summer. It is at the same time the location of maximal observed temperature anomalies during the heat waves 2003. Currently summer temperature changes induced by land cover modification is yet unclear at these latitudes. The differences in vegetation cover correspond to conversion of agricultural land use to natural grassland and forest and can be compared to a reforestation of about 45% of the domains surface. By replacing the agricultural vegetation by a mixture of forests and prairies, the mean capacity of photosynthetic activity is reduced due to increased stomatal resistance and smaller LAI. The exceptional meteorological conditions in 2003 enhance development of the cover of vegetation in both simulations and result in great photosynthetic activity and transpiration. The simulation with current vegetation cover (CUR) is colder during the first heat wave in June due to large evapotranspiration of the agricultural plants. Plants start to get limited in soil moisture in July. Vegetation in CUR is most affected and starts welting. In this circumstances the simulation without human impact on land cover plays out its advantage of greater heat resilience on the long term. During the second heat wave in August the repartition of turbulent heat fluxes .

Stéfanon, Marc; Schindler, Solveig; Drobinski, Philippe; de Noblet-Ducoudré, Nathalie; D'Andrea, Fabio

2013-04-01

311

When valence bond wave functions are analyzed through QTAIM: Conceptual incompatibilities in H2  

NASA Astrophysics Data System (ADS)

Hydrogen molecule was chosen, for simplicity, to analyze its valence bond (VB) wave function with the Quantum Theory of Atoms in Molecules (QTAIM). We find that the usual association of its covalent and ionic contributions to individual Lewis structures does not agree with the localization and delocalization indices between both hydrogens defined within the QTAIM framework. Concretely, we analyzed the dependence of both indices with the internuclear distance and with different ionic/covalent relative weightings. The results indicate that QTAIM localization and delocalization indices should not be estimated from interpretations of the VB wave function in terms of the Lewis model.

Ferro-Costas, David; Mosquera, Ricardo A.

2015-01-01

312

Selected new developments in vibrational structure theory: potential construction and vibrational wave function calculations.  

PubMed

This perspective addresses selected recent developments in the theoretical calculation of vibrational spectra, energies, wave functions and properties. The theoretical foundation and recently developed computational protocols for constructing hierarchies of vibrational Hamiltonian operators are reviewed. A many-mode second quantization (SQ) formulation is discussed prior to the discussion of anharmonic wave functions. Emphasis is put on vibrational self-consistent field (VSCF) based methods and in particular vibrational coupled cluster (VCC) theory. Other issues are also reviewed briefly, such as inclusion of thermal effects, response theoretical calculation of spectra, and the difficulty in treating dense spectra. PMID:22491444

Christiansen, Ove

2012-04-10

313

Wave function collapses in a single spin magnetic resonance force microscopy  

E-print Network

We study the effects of wave function collapses in the oscillating cantilever driven adiabatic reversals (OSCAR) magnetic resonance force microscopy (MRFM) technique. The quantum dynamics of the cantilever tip (CT) and the spin is analyzed and simulated taking into account the magnetic noise on the spin. The deviation of the spin from the direction of the effective magnetic field causes a measurable shift of the frequency of the CT oscillations. We show that the experimental study of this shift can reveal the information about the average time interval between the consecutive collapses of the wave function

Berman, G P; Tsifrinovich, V I

2004-01-01

314

Wave function collapses in a single spin magnetic resonance force microscopy  

E-print Network

We study the effects of wave function collapses in the oscillating cantilever driven adiabatic reversals (OSCAR) magnetic resonance force microscopy (MRFM) technique. The quantum dynamics of the cantilever tip (CT) and the spin is analyzed and simulated taking into account the magnetic noise on the spin. The deviation of the spin from the direction of the effective magnetic field causes a measurable shift of the frequency of the CT oscillations. We show that the experimental study of this shift can reveal the information about the average time interval between the consecutive collapses of the wave function

G. P. Berman; F. Borgonovi; V. I. Tsifrinovich

2004-04-20

315

On wave function renormalization and related aspects in heavy fermion effective field theories  

E-print Network

We reconsider the question of wave function renormalization in heavy fermion effective field theories. In particular, we work out a simple and efficient scheme to define the wave function renormalization with respect to the lowest order heavy fermion propagator. The method presented is free of a set of ambiguities which arise in heavy fermion effective field theories. In this context, we discuss the approaches used in the literature so far. We also calculate the fourth order pion mass contribution to the nucleon mass shift and discuss the tree and loop contributions to the electric Sachs form factor of the nucleon.

Sven Steininger; Ulf-G. Meißner; Nadia Fettes

1998-08-10

316

Cut-off frequencies of Lamb waves in various functionally graded thin films  

NASA Astrophysics Data System (ADS)

An analytical study is carried out on the cut-off frequencies of Lamb waves in freestanding thin films made of various functionally graded elastic, piezoelectric, or piezoelectric-piezomagnetic materials. Results show that the set of cut-off frequencies is a union of two series of approximate arithmetic progression, in which the differences are inversely proportional to the definite integral of a function of the material parameters along thickness. Given the simple and universal relationship between cut-off frequencies and material parameters, this study provides theoretical guidance not only for nondestructive evaluation in engineering applications but for designing high-performance sensors based on Lamb waves.

Cao, Xiaoshan; Shi, Junping; Jin, Feng

2011-09-01

317

Phase-resolved imaging of confined exciton-polariton wave functions in elliptical traps  

NASA Astrophysics Data System (ADS)

We study the wave functions of exciton polaritons trapped in the elliptical traps of a patterned microcavity. A homodyne detection setup with numerical off-axis filtering allows us to retrieve the amplitude and the phase of the wave functions. Doublet states are observed as the result of the ellipticity of the confinement potential and are successfully compared to even and odd solutions of Mathieu equations. We also show how superpositions of odd and even states can be used to produce “donut” and “eight-shape” states which can be interpreted as polariton vortices.

Nardin, Gaël; Léger, Yoan; Pietka, Barbara; Morier-Genoud, François; Deveaud-Plédran, Benoît

2010-07-01

318

Clustering Properties and Model Wave Functions for Non-Abelian Fractional Quantum Hall Quasielectrons  

SciTech Connect

We present model wave functions for quasielectron (as opposed to quasihole) excitations of the unitary Z{sub k} parafermion sequence (Laughlin, Moore-Read, or Read-Rezayi) of fractional quantum Hall states. We uniquely define these states through two generalized clustering conditions: they vanish when either a cluster of k+2 electrons is put together or when two clusters of k+1 electrons are formed at different positions. For Abelian fractional quantum Hall states (k=1), our construction reproduces the Jain quasielectron wave function and elucidates the difference between the Jain and Laughlin quasielectrons.

Bernevig, B. Andrei [Princeton Center for Theoretical Physics, Princeton, New Jersey 08544 (United States); Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Haldane, F. D. M. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2009-02-13

319

Coupling of surge and waves for an Ivan-like hurricane impacting the Tampa Bay, Florida region  

NASA Astrophysics Data System (ADS)

The interactions between waves and storm surge are investigated using an unstructured grid, coupled wave-surge model forced by a hypothetical Ivan-like hurricane impacting the Tampa Bay, Florida region. The waves derived from the unstructured version of the third-generation wave model simulating waves nearshore. The surge derives from the unstructured Finite-Volume Coastal Ocean Model, to which wave-induced forces (based on radiation stress theory) are added to the traditional forces by winds and atmospheric pressure. Dependent upon complex bathymetry and geometry, the wave-induced forces result in an additional 0.3˜0.5 m of surge relative to an uncoupled, surge-only simulation, and the increase in coastal sea level by the storm surge adds some 1.0˜1.5 m to the significant wave heights nearshore. Such strong interactions through coupling suggest that waves should not be omitted in hurricane storm surge simulations, especially because the forces by waves on coastal structures are perhaps the most damaging of the hurricane related forces.

Huang, Yong; Weisberg, Robert H.; Zheng, Lianyuan

2010-12-01

320

Automated calculation of anharmonic vibrational contributions to first hyperpolarizabilities: quadratic response functions from vibrational configuration interaction wave functions.  

PubMed

Quadratic response functions are derived and implemented for a vibrational configuration interaction state. Combined electronic and vibrational quadratic response functions are derived using Born-Oppenheimer vibronic product wave functions. Computational tractable expressions are derived for determining the total quadratic response contribution as a sum of contributions involving both electronic and vibrational linear and quadratic response functions. In the general frequency-dependent case this includes a new and more troublesome type of electronic linear response function. Pilot calculations for the FH, H(2)O, CH(2)O, and pyrrole molecules demonstrate the importance of vibrational contributions for accurate comparison to experiment and that the vibrational contributions in some cases can be very large. The calculation of transition properties between vibrational states is combined with sum-over-states expressions for analysis purposes. On the basis of this some simple analysis methods are suggested. Also, a preliminary study of the effect of finite lifetimes on quadratic response functions is presented. PMID:20568841

Hansen, Mikkel Bo; Christiansen, Ove; Hättig, Christof

2009-10-21

321

Waves generated by Asteroid impacts and their effects on US shorelines  

NASA Astrophysics Data System (ADS)

On February 15, 2013 an undetected ~17-20-m diameter asteroid entered earth's atmosphere and, due to its large entry speed of 18.6 km/s and its shallow entry angle, the asteroid exploded in an airburst over Chelyabinsk, Russia, generating a bright flash, producing many small fragment meteorites and causing a powerful shock wave which released the equivalent of ~440 kt TNT of energy. About 16 hours after the Chelyabinsk asteroid, the elongated ~20m by ~40m (~30 m diameter) NEA 2012 DA14 with an estimated mass of 40 kt neared the earth surface at ~28,100km, ~2.2 earth's diameter. These two consecutive events, which were unrelated and had drastically different orbits, generated considerable attention and awareness from the public, confusion among the local residents, and raised the issue of emergency response and preparedness of local, state and government agencies. LLNL and other government agencies have performed numerical simulations of a postulated asteroid impact onto the ocean and generated data to support an emergency preparedness exercise. We illustrate the exercise through the application of several codes from source (asteroid entry) to ocean impact (splash rim) to wave generation, propagation and interaction with the shoreline. Using state-of-the-art high performance computing codes we simulate three impact sites; one site is located off the eat coat by Maryland's shoreline and two other sites on the west coast: the San Francisco bay and the Los Angeles bay shorelines, respectively. Simulations were conducted not only under deterministic conditions but also under conditions of uncertainty. Uncertainty assessment of flood hazards zones and structural integrity of infrastructures will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and partially funded by the Laboratory Directed Research and Development Program at LLNL under tracking code 12-ERD-005.

Ezzedine, S. M.; Miller, P. L.; Dearborn, D. S.; Dennison, D. S.; Glascoe, L. G.; Antoun, T.

2013-12-01

322

Catastrophic impact of typhoon waves on coral communities in the Ryukyu Islands under global warming  

NASA Astrophysics Data System (ADS)

Typhoon-generated storm waves generally cause mechanical damage to coral communities on present-day reefs, and the magnitude and extent of damage is predicted to increase in the near future as a result of global warming. Therefore, a comprehensive understanding of potential future scenarios of reef ecosystems is of prime interest. This study assesses the current status of coral communities on Ibaruma reef, Ryukyu Islands, on the basis of field observations, engineering and fluid dynamic models, and calculations of wave motion, and predicts the potential effects of a super-extreme typhoon (incident wave height,H = 20 m; wave period, T = 20 s) on the reef. On the present-day reef, massive corals occur in shallow lagoons and tabular corals occur from the reef crest to the reef slope. The observed distribution of corals, which is frequently attacked by moderate (H = 10 m, T = 10 s) and extreme (H = 10 m, T = 15 s) typhoons, is consistent with the predictions of engineering models. Moreover, this study indicates that if a super-extreme typhoon attacks the reef in the near future, massive corals will survive in the shallow lagoons but tabular corals on the reef crest and reef slope will be severely impacted. The findings imply that super-extreme typhoons will cause a loss of species diversity, as the tabular corals are important reef builders and are critical to the maintenance of reef ecosystems. Consequently, reef restoration is a key approach to maintaining reef ecosystems in the wake of super-extreme typhoons.

Hongo, Chuki; Kawamata, Hideki; Goto, Kazuhisa

2012-06-01

323

Modified Smoothed Particle Hydrodynamics (MSPH) basis functions for meshless methods, and their application to axisymmetric Taylor impact test  

NASA Astrophysics Data System (ADS)

The Modified Smoothed Particle Hydrodynamics (MSPH) method proposed earlier by the authors and applied to the analysis of transient two-dimensional (2-D) heat conduction, 1-D transient simple shearing deformations of a thermoviscoplastic material, 1-D wave propagation in a functionally graded plate, and 2-D elastodynamic crack propagation is extended to the analysis of axisymmetric deformations of a thermoviscoplastic material. In the MSPH method, different shape functions are used to find kernel estimates of the function, and of its first and second derivatives. It differs from the classical finite element method in which derivatives of a function are usually obtained by differentiating the shape function used to approximate the function. It is shown that results computed with the MSPH method for the Noh problem agree well with its analytical solution. The MSPH basis functions can be used in any meshless method to numerically solve either static or dynamic problems. The method is then applied to analyze transient deformations of a cylindrical rod impacting at normal incidence a rigid smooth stationary flat plate. The computed solution is found to agree very well with those obtained by analyzing axisymmetric and 3-D transient deformations of the rod with the commercial code LS-DYNA. The final length of the deformed rod, the final radius of the impacted face, and the final length of the relatively undeformed portion of the rod for twelve test configurations computed with the MSPH method are also found to agree well with their corresponding experimental values.

Batra, R. C.; Zhang, G. M.

324

Uniform approximation of wave functions with improved semiclassical transformation amplitudes and Gram-Schmidt orthogonalization  

NASA Astrophysics Data System (ADS)

Semiclassical transformation theory implies an integral representation for stationary-state wave functions ?m(q) in terms of angle-action variables ( ?,J ). It is a particular solution of Schrödinger’s time-independent equation when terms of order ?2 and higher are omitted, but the preexponential factor A(q,?) in the integrand of this integral representation does not possess the correct dependence on q . The origin of the problem is identified: the standard unitarity condition invoked in semiclassical transformation theory does not fix adequately in A(q,?) a factor which is a function of the action J written in terms of q and ? . A prescription for an improved choice of this factor, based on successfully reproducing the leading behavior of wave functions in the vicinity of potential minima, is outlined. Exact evaluation of the modified integral representation via the residue theorem is possible. It yields wave functions which are not, in general, orthogonal. However, closed-form results obtained after Gram-Schmidt orthogonalization bear a striking resemblance to the exact analytical expressions for the stationary-state wave functions of the various potential models considered (namely, a Pöschl-Teller oscillator and the Morse oscillator).

Davis, Edward D.

2004-09-01

325

Health monitoring using Lamb waves. Application to the characterization of low impacts in aerospace structures  

NASA Astrophysics Data System (ADS)

This work was devoted to the development of a health monitoring system assigned to aerospace applications. The application concerned the detection of low damaging impacts on composite structures due to the extreme sensitivity of this material to this kind of solicitation. The chosen health monitoring was based first on the excitation and reception of Lamb waves along the structure by using thin piezoelectric transducers (active monitoring) and second on a continuous monitoring with the same transducers (passive monitoring). Preliminary tests were performed on a composite plate and the sensitivity of the A0 mode to the damage was demonstrated. Concerning the passive monitoring, the study showed the ability to use the acoustic signature of the impact to detect a possible damage. Further tests were performed on a wingbox composite structure. This wingbox structure consisted of composite skins with variable thickness mounted onto a metallic substructure. Moreover, four stringers were bonded on these skins. The aim was to demonstrate the ability of the system to perform rapid inspections of complex structures. After the application of a serial of impacts at diffent locations of the composite wingbox, the feasibility of the health monitoring was demonstrated.

Grondel, Sebastien; Assaad, Jamal; Delebarre, Christophe

2002-11-01

326

Functional Connectivity between Brain Areas Estimated by Analysis of Gamma Waves  

PubMed Central

The goal of this study is to investigate functional connectivity between different brain regions by analyzing the temporal relationship of the maxima of gamma waves recorded in multiple brain areas. Local field potentials were recorded from motor cortex, hippocampus, entorhinal cortex and piriform cortex of rats. Gamma activity was filtered and separated into two bands; high (65–90Hz) and low (30–55Hz) gamma. Maxima for gamma activity waves were detected and functional connectivity between different brain regions was determined using Shannon entropy for perievent histograms for each pair channels. Significant Shannon entropy values were reported as connectivity factors. We defined a connectivity matrix based the connectivity factors between different regions. We found that maxima of low and high frequency gamma occur in strong temporal relationship between some brain areas, indicating the existence of functional connections between these areas. The spatial pattern of functional connections between brain areas was different for slow wave sleep and waking states. However for each behavioral state in the same animal the pattern of functional connections was stable over time within 30 minutes of continuous analysis and over a 5 day period. With the same electrode montage the pattern of functional connectivity varied from one subject to another. Analysis of the temporal relationship of maxima of gamma waves between various brain areas could be a useful tool for investigation of functional connections between these brain areas. This approach could be applied for analysis of functional alterations occurring in these connections during different behavioral tasks and during processes related to learning and memory. The specificity in the connectivity pattern from one subject to another can be explained by the existence of unique functional networks for each subject. PMID:23376499

Kheiri, Farshad; Bragin, Anatol; Engel, Jerome

2013-01-01

327

Functional connectivity between brain areas estimated by analysis of gamma waves.  

PubMed

The goal of this study is to investigate functional connectivity between different brain regions by analyzing the temporal relationship of the maxima of gamma waves recorded in multiple brain areas. Local field potentials were recorded from motor cortex, hippocampus, entorhinal cortex and piriform cortex of rats. Gamma activity was filtered and separated into two bands; high (65-90Hz) and low (30-55Hz) gamma. Maxima for gamma activity waves were detected and functional connectivity between different brain regions was determined using Shannon entropy for perievent histograms for each pair channels. Significant Shannon entropy values were reported as connectivity factors. We defined a connectivity matrix based the connectivity factors between different regions. We found that maxima of low and high frequency gamma occur in strong temporal relationship between some brain areas, indicating the existence of functional connections between these areas. The spatial pattern of functional connections between brain areas was different for slow wave sleep and waking states. However for each behavioral state in the same animal the pattern of functional connections was stable over time within 30min of continuous analysis and over a 5 day period. With the same electrode montage the pattern of functional connectivity varied from one subject to another. Analysis of the temporal relationship of maxima of gamma waves between various brain areas could be a useful tool for investigation of functional connections between these brain areas. This approach could be applied for analysis of functional alterations occurring in these connections during different behavioral tasks and during processes related to learning and memory. The specificity in the connectivity pattern from one subject to another can be explained by the existence of unique functional networks for each subject. PMID:23376499

Kheiri, Farshad; Bragin, Anatol; Engel, Jerome

2013-04-15

328

Thermal-wave fields in solid wedges using the Green function method: Theory and experiment  

NASA Astrophysics Data System (ADS)

In this work, we establish a theoretical model for a cylindrical rod of radius R with opening angle ? illuminated by a modulated incident beam. The model uses the Green function method in cylindrical coordinates. An analytical expression for the Green function and thermal-wave field in such a solid is presented. The theory is validated in the limit of reducing the arbitrary wedge geometrical structure to simpler geometries. For acute angle wedges, it is shown that the thermal-wave field near the edge exhibits confinement behavior and increased amplitude compared to a flat (reference) solid with ? = ?. For obtuse angle wedges, it is shown that the opposite is true and relaxation of confinement occurs leading to lower amplitude thermal-wave fields. The theory provides a basis for quantitative thermophysical characterization of wedge-shaped objects and it is tested using an AISI 304 steel wedge and photothermal radiometry detection.

Tai, Rui; Zhang, Jie; Wang, Chinhua; Mandelis, Andreas

2013-04-01

329

Complex Observation in Electron Microscopy. II. Direct Visualization of Phases and Amplitudes of Exit Wave Functions  

NASA Astrophysics Data System (ADS)

We report microscopic observation of complex waves emitted from objects. Two images sequentially detected at the image plane with two transmission electron microscopic (TEM) methods, the conventional and the phase-contrasted, are numerically combined to reproduce complex wave functions, which are holding complete optical information. The long lasting issue in conventional TEM that the contrast and the resolution of images are difficult to be simultaneously optimized was settled with the complex wave functions. The aberration-corrected phase images of ferritin (at 400 kV) and TMV (at 100 kV) did show an extraordinary high contrast free from image distortion without sacrificing the resolution compared with that obtained by conventional TEM.

Danev, Radostin; Nagayama, Kuniaki

2001-03-01

330

Channel-Coupling Contribution to the Widths of Decay Nuclear States and to Their Wave Functions  

SciTech Connect

By using the formalism of the quantum theory of fission, the amplitudes of partial decay widths and the asymptotic behavior of the wave function for a decaying nucleus are found with allowance for open-decay-channel coupling not only for fission, but also for the binary decays of nuclei through protonic, alpha-particle, cluster, and other channels.

Kadmensky, S.G. [Voronezh State University, Universitetskaya pl. 1, Voronezh, 394693 (Russian Federation)

2004-12-01

331

A wave-function Monte Carlo method for simulating conditional master equations  

E-print Network

Wave-function Monte Carlo methods are an important tool for simulating quantum systems, but the standard method cannot be used to simulate decoherence in continuously measured systems. Here we present a new Monte Carlo method for such systems. This was used to perform the simulations of a continuously measured nano-resonator in [Phys. Rev. Lett. 102, 057208 (2009)].

Kurt Jacobs

2009-06-25

332

Wave-function Monte Carlo method for simulating conditional master equations  

SciTech Connect

Wave-function Monte Carlo methods are an important tool for simulating quantum systems, but the standard method cannot be used to simulate decoherence in continuously measured systems. Here I present a Monte Carlo method for such systems. This was used to perform the simulations of a continuously measured nanoresonator in [Phys. Rev. Lett. 102, 057208 (2009)].

Jacobs, Kurt [Department of Physics, University of Massachusetts at Boston, Boston, Massachusetts 02125 (United States) and Hearne Institute for Theoretical Physics, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

2010-04-15

333

Semiclassical Green function calculation of four wave u-nixing in polarizable clusters and liquids  

E-print Network

. Simulation results for two-pulse ultrafast four wave mixing measurements in atomic clusters and in liquids Green function expression for the optical signal is developed and applied to analyze two pulse ultrafast that the relative time ordering of the two incoming pulses is reversed. The signal then no longer shows an echo

Mukamel, Shaul

334

SCA calculations of the inner shell ionization with Dirac-Fock electronic wave functions  

E-print Network

SCA calculations of the inner shell ionization with Dirac-Fock electronic wave functions Z. The theory of inner shell ionization for arbitrary atomic shells is reviewed. Emphasis is on L- and M- shells in order to show how the proper screening formalism entering the electronic form factor affects

Perger, Warren F.

335

Frequency-Domain Green's Functions for Radar Waves in Heterogeneous 2.5D Media  

EPA Science Inventory

Green?s functions for radar waves propagating in heterogeneous media may be calculated in the frequency domain using a hybrid of two numerical methods. The model is defined in the Cartesian coordinate system, and its electromagnetic properties may vary in the x and z directions, ...

336

MIMO Radar Space-Time Adaptive Processing Using Prolate Spheroidal Wave Functions  

E-print Network

1 MIMO Radar Space-Time Adaptive Processing Using Prolate Spheroidal Wave Functions Chun-Yang Chen and P. P. Vaidyanathan, Fellow, IEEE Abstract--In the traditional transmitting beamforming radar system- output (MIMO) radar system, the transmitter sends nonco- herent (possibly orthogonal) broad (possibly

Vaidyanathan, P. P.

337

Spin-s wave functions with algebraic order Onuttom Narayan and B. Sriram Shastry  

E-print Network

, i.e., has the same cor- relation exponents. In this paper, we propose a natural extension the model to a classical statistical mechanical model, which has coupled Ising spin chains with long range point value.7,8 An alternative recent line of thought has been to study explicit wave functions

California at Santa Cruz, University of

338

Three-Dimensional Visualization of Wave Functions for Rotating Molecule: Plot of Spherical Harmonics  

ERIC Educational Resources Information Center

At an early stage of learning quantum chemistry, undergraduate students usually encounter the concepts of the particle in a box, the harmonic oscillator, and then the particle on a sphere. Rotational levels of a diatomic molecule can be well approximated by the energy levels of the particle on a sphere. Wave functions for the particle in a…

Nagaoka, Shin-ichi; Teramae, Hiroyuki; Nagashima, Umpei

2013-01-01

339

Comparison of lattice Coulomb-gauge wave functions in the quenched approximation and with dynamical fermions  

SciTech Connect

We present a comparison of Coulomb-gauge wave functions from 6/[ital g][sup 2]=6.0 quenched simulations with two simulations which include the effects of dynamical fermions: simulations with two flavors of dynamical staggered quarks and valence Wilson quarks at 6/[ital g][sup 2]=5.6 and simulations with two flavors of dynamical Wilson quarks and Wilson valence quarks at 6/[ital g][sup 2]=5.3. The spectroscopy of these systems is essentially identical. Parametrizations of the wave functions are presented which can be used as interpolating fields for spectroscopy calculations. The sizes of particles are calculated using these parametrized wave functions. The resulting sizes are small, approximately half the sizes of the physical states. The charge radius of the neutron, which provides an indication of the asymmetries between the wave functions of up and down quarks, is calculated. Although the size of the nucleon in these simulations is small, the ratio of the charge radius of the neutron to that of the proton is consistent with the physical value. We find no significant differences between the quenched and dynamical simulations.

Hecht, M.W.; Bitar, K.M.; DeGrand, T.; Edwards, R.; Gottlieb, S.; Heller, U.M.; Kennedy, A.D.; Kogut, J.B.; Liu, W.; Ogilvie, M.C.; Renken, R.L.; Rossi, P.; Sinclair, D.K.; Sugar, R.L.; Wang, K.C. (National Center for Atmospheric Research, P.O. Box 3000, Boulder, Colorado 80307 (United States) Supercomputer Computations Research Institute, Florida State University, Tallahassee, Florida 32306 (United States) University of Colorado, Boulder, Colorado 80309 (United States) Indiana University, Bloomington, Indiana 47405 (United States) University of Illinois, Urbana, Illinois 61801 (United States) Thinking Machines Corporation, Cambridge, Massachusetts 02139 (United States) Washington University, St. Louis, Missouri 63130 (United States) University of Central Florida, Orlando, Florida 32816 (United States) Argonne National Laboratory, Argonne, Illinois 60439 (United States) University of California, Santa Barbara, California 93106 (United States) University of New South Wales, Kensington,

1993-01-01

340

The variational principle and simple properties of the ground-state wave function  

Microsoft Academic Search

The variational principle is used to show that the ground-state wave function of a one-body Schrödinger equation with a real potential is real, does not change sign, and is nondegenerate. As a consequence, if the Hamiltonian is invariant under rotations and parity transformations, the ground state must have positive parity and zero angular momentum.

J. Mur-Petit; A. Polls; F. Mazzanti

2002-01-01

341

Bloch Model Wave Functions and Pseudopotentials for All Fractional Chern Insulators  

NASA Astrophysics Data System (ADS)

We introduce a Bloch-like basis in a C-component lowest Landau level fractional quantum Hall (FQH) effect, which entangles the real and internal degrees of freedom and preserves an Nx×Ny full lattice translational symmetry. We implement the Haldane pseudopotential Hamiltonians in this new basis. Their ground states are the model FQH wave functions, and our Bloch basis allows for a mutatis mutandis transcription of these model wave functions to the fractional Chern insulator of arbitrary Chern number C, obtaining wave functions different from all previous proposals. For C>1, our wave functions are related to color-dependent magnetic-flux inserted versions of Halperin and non-Abelian color-singlet states. We then provide large-size numerical results for both the C=1 and C=3 cases. This new approach leads to improved overlaps compared to previous proposals. We also discuss the adiabatic continuation from the fractional Chern insulator to the FQH in our Bloch basis, both from the energy and the entanglement spectrum perspectives.

Wu, Yang-Le; Regnault, N.; Bernevig, B. Andrei

2013-03-01

342

Asymptotic scattering wave function for three charged particles and astrophysical capture processes  

E-print Network

particles are close to each other and far away from the third particle. This wave function satisfies the Schrodinger equation up to terms O(1/3pa), where pa is the distance between the center of mass of two particles and the third particle. The derived...

Pirlepesov, Fakhriddin

2006-08-16

343

A Study of the Slope Probability Density Function of the Ocean Waves from Radar Observations  

E-print Network

proposed by Barrick (1968), which represents the quasi-specular reflection from ocean facets. The slope pdf1 A Study of the Slope Probability Density Function of the Ocean Waves from Radar Observations D. Geophys. Research (Ocean), September 2007 hal-00144373,version1-19Nov2007 Author manuscript, published

Paris-Sud XI, Université de

344

NO EFFECT OF HYDRODYNAMIC SHOCK WAVE ON PROTEIN FUNCTIONALITY OF BEEF MUSCLE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The protein functionality of meat proteins after treatment with hydrodynamic shock wave was determined. Frankfurters (cooked to 71 deg C) were evaluated for cooking yield, CIE L*a*b*, nitrosylhemochrome, Texture Profile Analysis (hardness, cohesiveness), and stress and strain (torsion testing). Comp...

345

On the Asymptotic Expansion of the Spheroidal Wave Function and its Eigenvalues for Complex Size Parameter  

Microsoft Academic Search

We provide a rapid and accurate method for calculating the prolate and oblate spheroidal wave functions (PSWFs and OSWFs), Smn(c; ), and their eigenvalues, mn, for arbitrary complex size parameter c in the asymptotic regime of large jcj, m and n fixed. The ability to calculate these SWFs for large and complex size parameters is important for many applications in

Benjamin E. Barrowes; Kevin O'Neill; Tomasz M. Grzegorczyk; Jin A. Kong

2003-01-01

346

Asymptotic Expansions of the Prolate Angular Spheroidal Wave Function for Complex Size Parameter  

Microsoft Academic Search

We provide a rapid and accurate method for calculating the prolate spheroidal wave functions (PSWFs), Smn(c;·), and their eigenvalues, ‚mn, for complex size parameter c in the asymptotic regime of large jcj, m and n flxed. The ability to calculate these SWFs for large and complex size parameters is important for many applications in mathematics, engineering, and physics. Existing routines

KevinO' Neill

347

A new friendly method of computing prolate spheroidal wave functions and wavelets  

Microsoft Academic Search

Prolate spheroidal wave functions, because of their many remarkable properties leading to new applications, have recently experienced an upsurge of interest. They may be dened as eigenfunctions of either a dieren tial operator or an integral operator (as observed by Slepian in the 1960's). There are various ways of calculating their values based on both approaches. The standard one uses

G. Walter; T. Soleski

2005-01-01

348

Ultra wide band signal design by angular and radial prolate spheroidal wave functions (PSWF)  

Microsoft Academic Search

Prolate spheroidal wave functions (PSWF) provide significant advantage in ultra wideband (UWB) pulse-shapes design because of the time limited nature and wide bandwidth of such orthogonal signal waveforms. In this paper, we show the design procedure for UWB pulses utilizing the joining properties of radial and angular PSWF. Results in the paper demonstrate utility of eigenvalues and power spectral properties

D. Adhikari; C. Bhattacharya

2011-01-01

349

Reducing sampling error by prolate spheroidal wave functions and fractional Fourier transform  

Microsoft Academic Search

It is known that one can use Shannon's theory to sample a bandlimited signal. In this paper, we introduce how to use prolate spheroidal wave functions (PSWFs) to sample a time-limited and nearly band-limited signal. PSWFs have the property of optimal energy concentration. Thus we can apply it to sampling theory to reduce the aliasing error of the recovered signal.

Jian-Jiun Ding

2005-01-01

350

Asymptotic Expansions of the Prolate Angular Spheroidal Wave Function for Complex Size Parameter  

Microsoft Academic Search

We provide a rapid and accurate method for calculating the prolate spheroidal wave functions (PSWFs), Smn(c, ?), and their eigenvalues, ?mn, for complex size parameter c in the asymptotic regime of large |c|, m and n fixed. The ability to calculate these SWFs for large and complex size parameters is important for many applications in mathematics, engineering, and physics. Existing

Benjamin E. Barrowes; Tomasz M. Grzegorczyk; Jin Au Kong; Kevin O'Neill

351

New efficient methods of computing the prolate spheroidal wave functions and their corresponding eigenvalues  

Microsoft Academic Search

In this paper, we describe different methods of computing the eigenvalues associated with the prolate spheroidal wave functions (PSWFs). These eigenvalues play an important role in computing the values of PSWFs as well as in the different numerical applications based on these later. The methods given in this work are accurate, fast and valid for small as well as for

Abderrazek Karoui; Tahar Moumni

2008-01-01

352

Prolate spheroidal wave functions, an introduction to the Slepian series and its properties  

Microsoft Academic Search

For decades mathematicians, physicists, and engineers have relied on various orthogonal expansions such as Fourier, Legendre, and Chebyschev to solve a variety of problems. In this paper we exploit the orthogonal properties of prolate spheroidal wave functions (PSWF) in the form of a new orthogonal expansion which we have named the Slepian series. We empirically show that the Slepian series

Ian C. Moore; Michael Cada

2004-01-01

353

Impact of ethnicity and extreme prematurity on infant pulmonary function  

PubMed Central

The impact of birth before 27 completed weeks of gestation on infant pulmonary function (PF) was explored in a multi-ethnic population in comparison to more mature preterm controls (PTC) and healthy fullterm infants. Plethysmographic lung volume (FRCpleth) and forced expired volume (FEV0.5) were obtained at ?12 months post-term age in 52 extremely preterm (EP) infants (median [range] gestational age [GA]: 26 [23–27] weeks; 40% White mothers; 79% with BPD), 41 PTC (GA:35 [30–36] weeks; 37% White mothers) and 95 fullterm infants (GA:40 [37–42] weeks; 86% White mothers). Using reference equations based on identical equipment and techniques, results were expressed as z-scores to adjust for age, sex and body size. FEV0.5 was significantly lower in EP infants when compared with PTC (mean difference [95% CI]: ?1.02[?1.60; ?0.44] z-scores, P < 0.001), as was forced vital capacity (FVC) but there were no significant differences in FRCpleth or FEV0.5/FVC ratio. FEV0.5, FVC, and FEV0.5/FVC were significantly lower in both preterm groups when compared with fullterm controls. On multivariable analyses of the combined preterm dataset: FEV0.5 at ?1 year was 0.11 [0.05; 0.17] z-scores higher/week GA, and 1.28 (0.49; 2.08) z-scores lower in EP infants with prior BPD. Among non-white preterm infants, FEV0.5 was 0.70 (0.17; 1.24) z-scores lower, with similar reductions in FVC, such that there were no ethnic differences in FEV0.5/FVC. Similar ethnic differences were observed among fullterm infants. These results confirm the negative impact of preterm birth on subsequent lung development, especially following a diagnosis of BPD, and emphasize the importance of taking ethnic background into account when interpreting results during infancy as in older subjects. PMID:24123888

Hoo, Ah-Fong; Gupta, Amit; Lum, Sooky; Costeloe, Kate L; Huertas-Ceballos, Angela; Marlow, Neil; Stocks, Janet

2014-01-01

354

Impact of ethnicity and extreme prematurity on infant pulmonary function.  

PubMed

The impact of birth before 27 completed weeks of gestation on infant pulmonary function (PF) was explored in a multi-ethnic population in comparison to more mature preterm controls (PTC) and healthy fullterm infants. Plethysmographic lung volume (FRCpleth ) and forced expired volume (FEV0.5 ) were obtained at ?12 months post-term age in 52 extremely preterm (EP) infants (median [range] gestational age [GA]: 26 [23-27] weeks; 40% White mothers; 79% with BPD), 41 PTC (GA:35 [30-36] weeks; 37% White mothers) and 95 fullterm infants (GA:40 [37-42] weeks; 86% White mothers). Using reference equations based on identical equipment and techniques, results were expressed as z-scores to adjust for age, sex and body size. FEV0.5 was significantly lower in EP infants when compared with PTC (mean difference [95% CI]: -1.02[-1.60; -0.44] z-scores, P?impact of preterm birth on subsequent lung development, especially following a diagnosis of BPD, and emphasize the importance of taking ethnic background into account when interpreting results during infancy as in older subjects. PMID:24123888

Hoo, Ah-Fong; Gupta, Amit; Lum, Sooky; Costeloe, Kate L; Huertas-Ceballos, Angela; Marlow, Neil; Stocks, Janet

2014-07-01

355

Spatial impacts of heat waves in mortality. Evaluating current risks and future threats  

NASA Astrophysics Data System (ADS)

Impacts of heat waves in morbidity and mortality are largely known. Climate Change is expected to increase the climate health impacts in summer while the winter will be probably favored. The health impacts of extreme thermal events are mainly studied at a national or regional level, considering macro or mesoscale thermal features. But it can be assumed that local variations in mortality must exist, associated, in one hand, with local climatic differences, due to features such as land use and urbanization and, in other hand, with vulnerability factors (depending on demographic and socioeconomic characteristics of populations). A model of hazard - vulnerability - risk was developed, to analyze the spatial variations of mortality in extreme thermal events, at the level of city district, in the Lisbon metropolitan area (Portugal). In that model, risk is considered as the product of hazard and vulnerability. Daily mortality data by sex, age and cause of death was supplied by the Health National Authority. The research is yet on-going. In our model, hazard is represented mainly by temperature and air pollution (the influence of other atmospheric variables that affect the human energy balance, such as solar radiation and wind speed should be tested too). Small scale variation of meteorological features, in extreme thermal events, were simulated with a Regional Atmospheric Model (Brazilian Regional Atmospheric Modeling System) and the results were validated and calibrated using observation data from an urban network of termo-higrometers placed in sites with different urban characteristics. Vulnerability is a result on personal sensitivity and exposure. Personal sensitivity is assessed considering individual constitutional and demographic factors as well as socio, cultural and economic variables. Daily mobility determines the population exposure to heat. Since many of these variables are redundant, a set of indicators, including a multiple deprivation index, was used. A first step consists in the modelling of the current relationship between hazard factors, vulnerability and mortality with the aim to explain the variations in mortality, at the city-district scale. In a second step, changes in hazard and vulnerability factors will be simulated. In the changes in meteorological conditions, IPCC and SIAM II scenarios were considered, as well as previsions of urban development and land use changes in the studied area. Demographic and socioeconomic changes should be simulated too. The pretended result with this risk assessment methodology is a prevision of future impacts (intensity and patterns) of the heat waves on mortality.

Andrade, H.; Canario, P.; Nogueira, H.

2009-09-01

356

"Electron ping-pong" on a one-dimensional lattice: Multiple reflections of the wave packet and capture of the wave function by an acceptor  

NASA Astrophysics Data System (ADS)

Considering the problem of multiple reflections of a wave function from the ends of a lattice, we observe an interesting phenomenon: the wave function amplitude is concentrated on the impurity center after reflections. The solution obtained by expanding the total wave function a(t) on the impurity center in the partial amplitudes ak(t), whose contributions become essential only after the kth reflection from the lattice end, seems to agree very well with the results of numerical modeling. We solve the problem of the capture of the wave function by an acceptor. The obtained results can be used to explain experimental data on charge transfer in artificial oligonucleotides and polypeptides. We find expressions for the electron capture probability in some limit cases, which can be considered estimates of the quantum output of the charge transport.

Likhachev, V. N.; Astakhova, T. Yu.; Vinogradov, G. A.

2013-08-01

357

Crack detection in a wheel end spindle using wave propagation via modal impacts and piezo actuation  

NASA Astrophysics Data System (ADS)

This research demonstrates two methodologies for detecting cracks in a metal spindle housed deep within a vehicle wheel end assembly. First, modal impacts are imposed on the hub of the wheel in the longitudinal direction to produce broadband elastic wave excitation spectra out to 7000 Hz. The response data on the flange is collected using 3000 Hz bandwidth accelerometers. It is shown using frequency response analysis that the crack produces a filter, which amplifies the elastic response of the surrounding components of the wheel assembly. Experiments on wheel assemblies mounted on the vehicle with the vehicle lifted off the ground are performed to demonstrate that the modal impact method can be used to nondestructively evaluate cracks of varying depths despite sources of variability such as the half shaft angular position relative to the non-rotating spindle. Second, an automatic piezo-stack actuator is utilized to excite the wheel hub with a swept sine signal extending from 20 kHz. Accelerometers are then utilized to measure the response on the flange. It is demonstrated using frequency response analysis that the crack filters waves traveling from the hub to the flange. A simple finite element model is used to interpret the experimental results. Challenges discussed include variability from assembly to assembly, the variability in each assembly, and the high amount of damping present in each assembly due to the transmission gearing, lubricant, and other components in the wheel end. A two-channel measurement system with a graphical user interface for detecting cracks was also developed and a procedure was created to ensure that operators properly perform the test.

Ackers, Spencer; Evans, Ronald; Johnson, Timothy; Kess, Harold; White, Jonathan; Adams, Douglas E.; Brown, Pam

2006-03-01

358

The impact of heat, cold, and heat waves on hospital admissions in eight cities in Korea  

NASA Astrophysics Data System (ADS)

Although the impact of temperature on mortality is well documented, relatively fewer studies have evaluated the associations of temperature with morbidity outcomes such as hospital admissions, and most studies were conducted in North America or Europe. We evaluated weather and hospital admissions including specific causes (allergic disease, asthma, selected respiratory disease, and cardiovascular disease) in eight major cities in Korea from 2003 to 2008. We also explored potential effect modification by individual characteristics such as sex and age. We used hierarchical modeling to first estimate city-specific associations between heat, cold, or heat waves and hospitalizations, and then estimated overall effects. Stratified analyses were performed by cause of hospitalization, sex, and age (0-14, 15-64, 65-74, and ?75 years). Cardiovascular hospitalizations were significantly associated with high temperature, whereas hospitalizations for allergic disease, asthma, and selected respiratory disease were significantly associated with low temperature. The overall heat effect for cardiovascular hospitalization was a 4.5 % (95 % confidence interval 0.7, 8.5 %) increase in risk comparing hospitalizations at 25 to 15 °C. For cold effect, the overall increase in risk of hospitalizations comparing 2 with 15 °C was 50.5 (13.7, 99.2 %), 43.6 (8.9, 89.5 %), and 53.6 % (9.8, 114.9 %) for allergic disease, asthma, and selected respiratory disease, respectively. We did not find statistically significant effects of heat waves compared with nonheat wave days. Our results suggest susceptible populations such as women and younger persons. Our findings provide suggestive evidence that both high and low ambient temperatures are associated with the risk of hospital admissions, particularly in women or younger person, in Korea.

Son, Ji-Young; Bell, Michelle L.; Lee, Jong-Tae

2014-01-01

359

De Broglie wavelets versus Schroedinger wave functions: A ribbon model approach to quantum theory and the mechanisms of quantum interference  

SciTech Connect

As an alternative to better physical explanations of the mechanisms of quantum interference and the origins of uncertainty broadening, a linear hopping model is proposed with ``color-varying`` dynamics to reflect fast exchange between time-reversed states. Intricate relations between this model, particle-wave dualism, and relativity are discussed. The wave function is shown to possess dual characteristics of a stable, localized ``soliton-like`` de Broglie wavelet and a delocalized, interfering Schroedinger carrier wave function.

Tang, Jau

1996-02-01

360

A numerically stable formulation of the Green's function parabolic equation: Subtracting the surface-wave pole.  

PubMed

The original formulation of the Green's function parabolic equation (GFPE) can have numerical accuracy problems for large normalized surface impedances. To solve the accuracy problem, an improved form of the GFPE has been developed. The improved GFPE formulation is similar to the original formulation, but it has the surface-wave pole "subtracted." The improved GFPE is shown to be accurate for surface impedances varying over 2 orders of magnitude, with the largest having a magnitude exceeding 1000. Also, the improved formulation is slightly faster than the original formulation because the surface-wave component does not have to be computed separately. PMID:25618104

Gilbert, Kenneth E

2015-01-01

361

Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media  

USGS Publications Warehouse

Green's functions for radar waves propagating in heterogeneous 2.5D media might be calculated in the frequency domain using a hybrid method. The model is defined in the Cartesian coordinate system, and its electromagnetic properties might vary in the x- and z-directions, but not in the y-direction. Wave propagation in the x- and z-directions is simulated with the finite-difference method, and wave propagation in the y-direction is simulated with an analytic function. The absorbing boundaries on the finite-difference grid are perfectly matched layers that have been modified to make them compatible with the hybrid method. The accuracy of these numerical Greens functions is assessed by comparing them with independently calculated Green's functions. For a homogeneous model, the magnitude errors range from -4.16% through 0.44%, and the phase errors range from -0.06% through 4.86%. For a layered model, the magnitude errors range from -2.60% through 2.06%, and the phase errors range from -0.49% through 2.73%. These numerical Green's functions might be used for forward modeling and full waveform inversion. ?? 2009 Society of Exploration Geophysicists. All rights reserved.

Ellefsen, K.J.; Croize, D.; Mazzella, A.T.; McKenna, J.R.

2009-01-01

362

Time asymptotics of the Schroedinger wave function in time-periodic potentials  

E-print Network

We study the transition to the continuum of an initially bound quantum particle in $\\RR^d$, $d=1,2,3$, subjected, for $t\\ge 0$, to a time periodic forcing of arbitrary magnitude. The analysis is carried out for compactly supported potentials, satisfying certain auxiliary conditions. It provides complete analytic information on the time Laplace transform of the wave function. From this, comprehensive time asymptotic properties (Borel summable transseries) follow. We obtain in particular a criterion for whether the wave function gets fully delocalized (complete ionization). This criterion shows that complete ionization is generic and provides a convenient test for particular cases. When satisfied it implies absence of discrete spectrum and resonances of the associated Floquet operator. As an illustration we show that the parametric harmonic perturbation of a potential chosen to be any nonzero multiple of the characteristic function of a measurable compact set has this property.

O. Costin; R. D. Costin; J. L. Lebowitz

2006-08-13

363

Final-state ?2 wave function in ion-helium collisions  

NASA Astrophysics Data System (ADS)

In this work we study the double-differential cross sections (DDCSs) of ejected electrons in single-ionization collisions of protons with helium atoms. The final state of the emitted electron is modeled by the correlated wave function ?2, a confluent hypergeometric function of two variables. We introduce a series representation of the ?2 wave function in terms of two-body Coulomb-like states, corresponding to the electron-projectile and electron-target relative motions. We consider undistorted and eikonal initial states that give rise to the Born ?2 and eikonal initial-state ?2 approximations, respectively. In both cases we obtain analytic series representations of the transition matrices, which exhibit a strong numerical convergence. We obtain DDCSs in ion-helium collisions in the intermediate- to high-energy regime with the Born ?2 approximation and show that it qualitatively agrees with the available experimental data.

Colavecchia, F. D.; Gasaneo, G.; Garibotti, C. R.

1998-10-01

364

Relations Between Low-lying Quantum Wave Functions and Solutions of the Hamilton-Jacobi Equation  

E-print Network

We discuss a new relation between the low lying Schroedinger wave function of a particle in a one-dimentional potential V and the solution of the corresponding Hamilton-Jacobi equation with -V as its potential. The function V is $\\geq 0$, and can have several minina (V=0). We assume the problem to be characterized by a small anhamornicity parameter $g^{-1}$ and a much smaller quantum tunneling parameter $\\epsilon$ between these different minima. Expanding either the wave function or its energy as a formal double power series in $g^{-1}$ and $\\epsilon$, we show how the coefficients of $g^{-m}\\epsilon^n$ in such an expansion can be expressed in terms of definite integrals, with leading order term determined by the classical solution of the Hamilton-Jacobi equation. A detailed analysis is given for the particular example of quartic potential $V={1/2}g^2(x^2-a^2)^2$.

R. Friedberg; T. D. Lee; W. Q. Zhao

1999-10-12

365

Mountain Torques Caused by Normal-Mode Global Rossby Waves, and the Impact on Atmospheric Angular Momentum.  

NASA Astrophysics Data System (ADS)

Planetary-scale free Rossby waves present in the earth's atmosphere propagate toward the west. Pressure torques varying in time then arise as a consequence of unequal pressure on the eastern and western sides of mountains and small-scale topographic features. These torques, referred to as mountain torques, have an influence on the exchange of angular momentum between the atmosphere and the earth.The authors investigated the impact of all identified planetary-scale free Rossby waves on atmospheric angular momentum by computing the contribution from mountain torques to the rate of change of total atmospheric angular momentum for each wave.Comparing contributions from individual waves, the authors found that for the average wave amplitudes the maximum torque for a particular wave is around 2 Hadleys, and that considering all meridional wavenumbers, zonal wavenumber 2 causes the largest global torques. Changes in angular momentum depend on both the amplitude of the changing torque and on its period. As a result zonal wavenumbers 1 and 2 cause the largest angular momentum anomalies with peak-to-trough amplitudes of 2-5 × 1023 kg m2 s1. The 16-day wave produces the largest amplitude, 4.9 × 1023 kg m2 s1. These values refer to average amplitudes reported in the literature. Individual waves may cause anomalies five times as big.

Lejenäs, Harald; Madden, Roland A.

2000-04-01

366

Modeling the functional network of primary intercellular Ca$^{2+}$ wave propagation in astrocytes and its application to study drug effects  

E-print Network

We introduce a simple procedure of multivariate signal analysis to uncover the functional connectivity among cells composing a living tissue and describe how to apply it for extracting insight on the effect of drugs in the tissue. The procedure is based on the covariance matrix of time resolved activity signals. By determining the time-lag that maximizes covariance, one derives the weight of the corresponding connection between cells. Introducing simple constraints, it is possible to conclude whether pairs of cells are functionally connected and in which direction. After testing the method against synthetic data we apply it to study intercellular propagation of Ca$^{2+}$ waves in astrocytes following an external stimulus, with the aim of uncovering the functional cellular connectivity network. Our method proves to be particularly suited for this type of networking signal propagation where signals are pulse-like and have short time-delays, and is shown to be superior to standard methods, namely a multivariate Granger algorithm. Finally, based the statistical analysis of the connection weight distribution, we propose simple measures for assessing the impact of drugs on the functional connectivity between cells.

Marcelo Pires; Frank Raischel; Sandra Vaz; Andreia Cruz-Silva; Ana Sebastião; Pedro G. Lind

2014-06-10

367

Modeling the functional network of primary intercellular Ca2+ wave propagation in astrocytes and its application to study drug effects.  

PubMed

We introduce a simple procedure of multivariate signal analysis to uncover the functional connectivity among cells composing a living tissue and describe how to apply it for extracting insight on the effect of drugs in the tissue. The procedure is based on the covariance matrix of time resolved activity signals. By determining the time-lag that maximizes covariance, one derives the weight of the corresponding connection between cells. Introducing simple constraints, it is possible to conclude whether pairs of cells are functionally connected and in which direction. After testing the method against synthetic data we apply it to study intercellular propagation of Ca(2+) waves in astrocytes following an external stimulus, with the aim of uncovering the functional cellular connectivity network. Our method proves to be particularly suited for this type of networking signal propagation where signals are pulse-like and have short time-delays, and is shown to be superior to standard methods, namely a multivariate Granger algorithm. Finally, based on the statistical analysis of the connection weight distribution, we propose simple measures for assessing the impact of drugs on the functional connectivity between cells. PMID:24813072

Pires, Marcelo; Raischel, Frank; Vaz, Sandra H; Cruz-Silva, Andreia; Sebastião, Ana M; Lind, Pedro G

2014-09-01

368

Expansion of X-ray form factor for close shell using uncorrelated wave function  

SciTech Connect

The atomic scattering factor has been studied for Be+ve, and B+2ve ions using the uncorrelated wave function (Hartree-Fock (HF)) for inter particle electronic shells. The physical importance of this factor appears in its relation to several important atomic properties as, the coherent scattering intensity, the total scattering intensity, the incoherent scattering function, the coherent scattering cross section, the total incoherent cross section, the nuclear magnetic shielding constant, the geometrical structure factor. Also there is one atomic properties the one particle radial density distribution function D(r)has been studied using the partitioning technique.

AL-Robayi, Enas M. [Babylon University , College of Science for Women, laser Physics Department, Hilla (Iraq)

2013-12-16

369

Assessments of Arterial Stiffness and Endothelial Function Using Pulse Wave Analysis  

PubMed Central

Conventionally, the assessments of endothelial function and arterial stiffness require different sets of equipment, making the inclusion of both tests impractical for clinical and epidemiological studies. Pulse wave analysis (PWA) provides useful information regarding the mechanical properties of the arterial tree and can also be used to assess endothelial function. PWA is a simple, valid, reliable, and inexpensive technique, offering great clinical and epidemiological potential. The current paper will outline how to measure arterial stiffness and endothelial function using this technique and include discussion of validity and reliability. PMID:22666595

Stoner, Lee; Young, Joanna M.; Fryer, Simon

2012-01-01

370

Global Propagation of Gravity Waves Generated with the Whole Atmosphere Transfer Function Model  

NASA Astrophysics Data System (ADS)

Gravity waves are ubiquitous phenomena in the Earth's atmosphere, accounting for a significant fraction of its observed variability. These waves, with periods ranging from minutes to hours, are thought to be a major means for exchange of momentum and energy between atmospheric regions. The Transfer Function Model (TFM) describes acoustic gravity waves (AGW) that propagate across the globe in a dissipative static background atmosphere extending from the ground to 700 km. The model is limited to waves with periods << 12 hr where the Coriolis force is not important. Formulated in terms of zonal vector spherical harmonics and oscillation frequencies, the linearized equations of energy, mass, and momentum conservation are solved to generate the transfer function (TF) for a chosen height distribution of the excitation source. The model accounts for momentum exchange between atmospheric species (He, O, N2, O2, Ar), which affects significantly the wave amplitudes and phases of thermospheric temperature, densities, and wind fields. Covering a broad range of frequencies and spherical harmonic wave numbers (wavelengths), without limitations, the assembled TF captures the physics that controls the propagation of AGW, and the computational effort is considerable. For a chosen horizontal geometry and impulsive time dependence of the source, however, the global wave response is then obtained in short order. The model is computationally efficient and well suited to serve as an experimental and educational tool for simulating propagating wave patterns on the globe. The model is also semi-analytical and therefore well suited to explore the different wave modes that can be generated under varying dynamical conditions. The TFM has been applied to simulate the AGW, which are generated in the auroral region of the thermosphere by joule heating and momentum coupling due to solar wind induced electric fields [e.g., Mayr et al., Space Science Reviews, 1990]. The auroral source generates three distinct classes of waves: (1) Lamb waves that propagate in the thermosphere with about 800 m/s, strongly dissipated by molecular viscosity. (2) Waves reflected from the Earth surface, which return in narrow propagation cones to the thermosphere with velocities of about 200 m/s. (3) Waves that are ducted through the lower atmosphere and leak back into the thermosphere, where they propagate with about 300 m/s, virtually without dissipation. Waves from the leaking duct, with short propagation velocity, thus can propagate from the auroral region to equatorial latitudes, and this has been observed. The TFM has been applied to simulate AGW patterns during magnetic sub-storm activity observed with the Dynamics Explorer (DE) spacecraft. The TFM can readily be employed also to simulate AGW generated with excitation sources in the lower atmosphere, and efforts are underway to resurrect the model with present day advanced computers and analysis software [e.g., Porter et al., AGU, 2008].

Mayr, H. G.; Talaat, E. R.; Wolven, B. C.

2012-12-01

371

An accurate Fortran code for computing hydrogenic continuum wave functions at a wide range of parameters  

NASA Astrophysics Data System (ADS)

The accurate computations of hydrogenic continuum wave functions are very important in many branches of physics such as electron-atom collisions, cold atom physics, and atomic ionization in strong laser fields, etc. Although there already exist various algorithms and codes, most of them are only reliable in a certain ranges of parameters. In some practical applications, accurate continuum wave functions need to be calculated at extremely low energies, large radial distances and/or large angular momentum number. Here we provide such a code, which can generate accurate hydrogenic continuum wave functions and corresponding Coulomb phase shifts at a wide range of parameters. Without any essential restrict to angular momentum number, the present code is able to give reliable results at the electron energy range [10,10] eV for radial distances of [10,10] a.u. We also find the present code is very efficient, which should find numerous applications in many fields such as strong field physics. Program summaryProgram title: HContinuumGautchi Catalogue identifier: AEHD_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHD_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1233 No. of bytes in distributed program, including test data, etc.: 7405 Distribution format: tar.gz Programming language: Fortran90 in fixed format Computer: AMD Processors Operating system: Linux RAM: 20 MBytes Classification: 2.7, 4.5 Nature of problem: The accurate computation of atomic continuum wave functions is very important in many research fields such as strong field physics and cold atom physics. Although there have already existed various algorithms and codes, most of them can only be applicable and reliable in a certain range of parameters. We present here an accurate FORTRAN program for calculating the hydrogenic continuum wave functions in a very wide range of parameters, which suffices the needs of most practical applications. The Coulomb phases are also calculated. For any given momentum, radial point, and the largest angular momentum number, the code calculates all the angular components at once. The algorithm we adopt has been given in details by Gautchi [1,2], who suggested a stable minimal solution of general three term recurrence relations. Solution method: Minimum solution of three-term recurrence relations developed by W. Gautchi [1,2]. Running time: A few seconds to a few minutes, depending how many different wave functions one needs to calculate.

Peng, Liang-You; Gong, Qihuang

2010-12-01

372

Reliability assessment of different plate theories for elastic wave propagation analysis in functionally graded plates.  

PubMed

The importance of elastic wave propagation problem in plates arises from the application of ultrasonic elastic waves in non-destructive evaluation of plate-like structures. However, precise study and analysis of acoustic guided waves especially in non-homogeneous waveguides such as functionally graded plates are so complicated that exact elastodynamic methods are rarely employed in practical applications. Thus, the simple approximate plate theories have attracted much interest for the calculation of wave fields in FGM plates. Therefore, in the current research, the classical plate theory (CPT), first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT) are used to obtain the transient responses of flexural waves in FGM plates subjected to transverse impulsive loadings. Moreover, comparing the results with those based on a well recognized hybrid numerical method (HNM), we examine the accuracy of the plate theories for several plates of various thicknesses under excitations of different frequencies. The material properties of the plate are assumed to vary across the plate thickness according to a simple power-law distribution in terms of volume fractions of constituents. In all analyses, spatial Fourier transform together with modal analysis are applied to compute displacement responses of the plates. A comparison of the results demonstrates the reliability ranges of the approximate plate theories for elastic wave propagation analysis in FGM plates. Furthermore, based on various examples, it is shown that whenever the plate theories are used within the appropriate ranges of plate thickness and frequency content, solution process in wave number-time domain based on modal analysis approach is not only sufficient but also efficient for finding the transient waveforms in FGM plates. PMID:23714123

Mehrkash, Milad; Azhari, Mojtaba; Mirdamadi, Hamid Reza

2014-01-01

373

The acoustical Klein-Gordon equation: The wave-mechanical step and barrier potential functions  

NASA Astrophysics Data System (ADS)

The transformed form of the Webster equation is investigated. Usually described as analogous to the Schrödinger equation of quantum mechanics, it is noted that the second-order time dependency defines a Klein-Gordon problem. This ``acoustical Klein-Gordon equation'' is analyzed with particular reference to the acoustical properties of wave-mechanical potential functions, U(x), that give rise to geometry-dependent dispersions at rapid variations in tract cross section. Such dispersions are not elucidated by other one-dimensional-cylindrical or conical-duct models. Since Sturm-Liouville analysis is not appropriate for inhomogeneous boundary conditions, the exact solution of the Klein-Gordon equation is achieved through a Green's-function methodology referring to the transfer matrix of an arbitrary string of square potential functions, including a square barrier equivalent to a radiation impedance. The general conclusion of the paper is that, in the absence of precise knowledge of initial conditions on the area function, any given potential function will map to a multiplicity of area functions of identical relative resonance characteristics. Since the potential function maps uniquely to the acoustical output, it is suggested that the one-dimensional wave physics is both most accurately and most compactly described within the Klein-Gordon framework.

Forbes, Barbara J.; Pike, E. Roy; Sharp, David B.

2003-09-01

374

Density-on-wave-function mapping beyond the Hohenberg-Kohn theorem  

NASA Astrophysics Data System (ADS)

Density-functional theory is based on the Hohenberg-Kohn theorem, establishing a one-on-one mapping between ground-state densities and wave functions. That theorem does not, however, make a direct statement on whether two wave functions that are in some sense close are mapped on two densities that are also close, and vice versa. In this work, a metric is defined that allows to quantify the meaning of ``close'' in the preceding sentence. This metric stratifies Hilbert space into concentric spheres on which maximum and minimum distances between states can be defined and geometrically interpreted. Numerical calculations for the Helium atom, Hooke's atom and a lattice Hamiltonian show that the mapping between densities and ground states, which is highly complex and nonlocal in the coordinate description, in metric space becomes a monotonic and nearly linear mapping of vicinities onto vicinities. In this sense, the density-on-wave-function mapping is not only simpler than expected; it is as simple as it could be. [4pt] I. D'Amico, J. P. Coe, V. V. Franca, and K. Capelle, Phys. Rev. Lett. 106, 050401 (2011) and Phys. Rev. Lett. 107, 188902 (2011). See also E. Artacho, Phys. Rev. Lett. 107, 188901 (2011).

Capelle, Klaus

2012-02-01

375

Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells  

PubMed Central

The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

2014-01-01

376

Characterization of a setup to test the impact of high-amplitude pressure waves on living cells.  

PubMed

The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O

2014-01-01

377

Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells  

NASA Astrophysics Data System (ADS)

The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction.

Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

2014-01-01

378

$U(1)\\times U(1)$ Symmetry Protected Topological Order in Gutzwiller Wave Functions  

E-print Network

Gutzwiller projection is a way to construct many-body wave functions that could carry topological order or symmetry protected topological (SPT) order. However, an important issue is to determine whether or not a given Gutzwiller-projected wave functions (GWF) carries a non-trivial SPT order, and which SPT order is carried by the wavefunction. In this paper, we numerically study the SPT order in a spin $S = 1$ GWF on the Kagome lattice. Using the standard Monte Carlo method, we directly confirm that the GWF has (1) gapped bulk with short-range correlations, (2) a trivial topological order via nondegenerate ground state, and zero topological entanglement entropy, (3) a non-trivial $U(1)\\times U(1)$ SPT order via the Hall conductances of the protecting $U(1)\\times U(1)$ symmetry, and (4) symmetry protected gapless boundary. This represents numerical evidence of continuous symmetry protected topological order in two-dimensional bosonic lattice systems.

Zheng-Xin Liu; Jia-Wei Mei; Peng Ye; Xiao-Gang Wen

2014-08-07

379

Semiclassical wave functions and semiclassical dynamics for the Kepler/Coulomb problem  

NASA Astrophysics Data System (ADS)

We investigate the semiclassical Kepler/Coulomb problem using the classical constants of the motion in the framework of Nelson’s stochastic mechanics. This is done by considering the eigenvalue relations for a family of coherent states (known as the atomic elliptic states) whose wave functions are concentrated on the elliptical orbit corresponding to the associated classical problem. We show that these eigenvalue relations lead to identities for the semiclassical energy, angular momentum and Hamilton-Lenz-Runge vectors in the elliptical case. These identities are then extended to include the cases of circular, parabolic and hyperbolic motions. We show that in all cases the semiclassical wave function is determined by our identities and so our identities can be seen as defining a semiclassical Kepler/Coulomb problem. The results are interpreted in terms of two dynamical systems: one a complex valued solution to the classical mechanics for a Coulomb potential and the other the drift field for a semiclassical Nelson diffusion.

Neate, Andrew; Truman, Aubrey

2014-06-01

380

Matter wave functions and Yukawa couplings in F-theory Grand Unification  

E-print Network

We study the local structure of zero mode wave functions of chiral matter fields in F-theory unification. We solve the differential equations for the zero modes derived from local Higgsing in the 8-dimensional parent action of F-theory 7-branes. The solutions are found as expansions both in powers and derivatives of the magnetic fluxes. Yukawa couplings are given by an overlap integral of the three wave functions involved in the interaction and can be calculated analytically. We provide explicit expressions for these Yukawas to second order both in the flux and derivative expansions and discuss the effect of higher order terms. We explicitly describe the dependence of the couplings on the U(1) charges of the relevant fields, appropriately taking into account their normalization. A hierarchical Yukawa structure is naturally obtained. The application of our results to the understanding of the observed hierarchies of quarks and leptons is discussed.

A. Font; L. E. Ibanez

2009-07-28

381

Form Factors and Wave Functions of Vector Mesons in Holographic QCD  

SciTech Connect

Within the framework of a holographic dual model of QCD, we develop a formalism for calculating form factors of vector mesons. We show that the holographic bound states can be described not only in terms of eigenfunctions of the equation of motion, but also in terms of conjugate wave functions that are close analogues of quantum-mechanical bound state wave functions. We derive a generalized VMD representation for form factors, and find a very specific VMD pattern, in which form factors are essentially given by contributions due to the first two bound states in the Q^2-channel. We calculate electric radius of the \\rho-meson, finding the value < r_\\rho^2>_C = 0.53 fm^2.

Hovhannes R. Grigoryan; Anatoly V. Radyushkin

2007-07-01

382

Second-order corrections to the wave function at the origin in muonic hydrogen and pionium  

SciTech Connect

Nonrelativistic second-order corrections to the wave function at the origin in muonic and exotic atoms are considered. The corrections are due to the electronic vacuum polarization. Such corrections are of interest due to various effective approaches, which take into account QED and hadronic effects. The wave function at the origin plays a key role in the calculation of the pionium lifetime, various finite nuclear size effects, and the hyperfine splitting. The results are obtained for the 1s and 2s states in pionic and muonic hydrogen and deuterium and in pionium, a bound system of {pi}{sup +} and {pi}{sup -}. Applications to the hyperfine structure and the Lamb shift in muonic hydrogen are also considered.

Ivanov, Vladimir G.; Korzinin, Evgeny Yu.; Karshenboim, Savely G. [Pulkovo Observatory, 196140, St. Petersburg, Russia and D. I. Mendeleev Institute for Metrology (VNIIM), St. Petersburg 198005 (Russian Federation); D. I. Mendeleev Institute for Metrology (VNIIM), St. Petersburg 198005 (Russian Federation); D. I. Mendeleev Institute for Metrology (VNIIM), St. Petersburg 198005, Russia and Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany)

2009-07-15

383

A First-Landau-Level Laughlin/Jain Wave Function for the Fractional Quantum Hall Effect  

E-print Network

We show that the introduction of a more general closed-shell operator allows one to extend Laughlin's wave function to account for the richer hierarchies (1/3, 2/5, 3/7 ...; 1/5, 2/9, 3/13, ..., etc.) found experimentally. The construction identifies the special hierarchy states with condensates of correlated electron clusters. This clustering implies a single-particle (ls)j algebra within the first Landau level (LL) identical to that of multiply filled LLs in the integer quantum Hall effect. The end result is a simple generalized wave function that reproduces the results of both Laughlin and Jain, without reference to higher LLs or projection.

Joe Ginocchio; Wick Haxton

1996-04-11

384

Entropy and Exact Matrix Product Representation of the Laughlin Wave Function  

E-print Network

An analytical expression for the von Neumann entropy of the Laughlin wave function is obtained for any possible bipartition between the particles described by this wave function, for filling fraction nu=1. Also, for filling fraction nu=1/m, where m is an odd integer, an upper bound on this entropy is exhibited. These results yield a bound on the smallest possible size of the matrices for an exact representation of the Laughlin ansatz in terms of a matrix product state. An analytical matrix product state representation of this state is proposed in terms of representations of the Clifford algebra. For nu=1, this representation is shown to be asymptotically optimal in the limit of a large number of particles.

S. Iblisdir; J. I. Latorre; R. Orus

2006-09-13

385

A First-Landau-Level Laughlin/Jain Wave Function for the Fractional Quantum Hall Effect  

SciTech Connect

We show that the introduction of a more general closed-shell operator allows one to extend Laughlin{close_quote}s wave function to account for the richer hierarchies (1/3,2/5,3/7...;1/5, 2/9,3/13,...,etc.) found experimentally. The construction identifies the special hierarchy states with condensates of correlated electron clusters. This clustering implies a single-particle algebra within the first Landau level (LL) identical to that of multiply filled LLs in the integer quantum Hall effect. The end result is a simple generalized wave function that reproduces the results of both Laughlin and Jain, without reference to higher LLs or projection. {copyright} {ital 1996 The American Physical Society.}

Ginocchio, J.N. [T-5, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [T-5, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Haxton, W.C. [Institute for Nuclear Theory, Box 351550, and Department of Physics, Box 351560, University of Washington, Seattle, Washington 98195-1550 (United States)] [Institute for Nuclear Theory, Box 351550, and Department of Physics, Box 351560, University of Washington, Seattle, Washington 98195-1550 (United States)

1996-08-01

386

Entropy and Exact Matrix-Product Representation of the Laughlin Wave Function  

SciTech Connect

An analytical expression for the von Neumann entropy of the Laughlin wave function is obtained for any possible bipartition between the particles described by this wave function, for a filling fraction {nu}=1. Also, for a filling fraction {nu}=1/m, where m is an odd integer, an upper bound on this entropy is exhibited. These results yield a bound on the smallest possible size of the matrices for an exact representation of the Laughlin ansatz in terms of a matrix-product state. An analytical matrix-product state representation of this state is proposed in terms of representations of the Clifford algebra. For {nu}=1, this representation is shown to be asymptotically optimal in the limit of a large number of particles.

Iblisdir, S.; Latorre, J. I. [Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, 647 Diagonal, 08028 Barcelona (Spain); Orus, R. [Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, 647 Diagonal, 08028 Barcelona (Spain); School of Physical Sciences, University of Queensland, QLD 4072 (Australia)

2007-02-09

387

The Transfer Function Model (TFM) as a Tool for Simulating Gravity Wave Phenomena in the Mesosphere  

NASA Astrophysics Data System (ADS)

The Transfer Function Model (TFM) is semi-analytical and linear, and it is designed to describe the acoustic gravity waves (GW) propagating over the globe and from the ground to 600 km under the influence of vertical temperature variations. Wave interactions with the flow are not accounted for. With an expansion in terms of frequency-dependent spherical harmonics, the time consuming vertical integration of the conservation equations is reduced to computing the transfer function (TF). (The applied lower and upper boundary conditions assure that spurious wave reflections will not occur.) The TF describes the dynamical properties of the medium divorced from the complexities of the temporal and horizontal variations of the excitation source. Given the TF, the atmospheric response to a chosen source is then obtained in short order to simulate the GW propagating through the atmosphere over the globe. In the past, this model has been applied to study auroral processes, which produce distinct wave phenomena such as: (1) standing lamb modes that propagate horizontally in the viscous medium of the thermosphere, (2) waves generated in the auroral oval that experience geometric amplification propagating to the pole where constructive interference generates secondary waves that propagate equatorward, (3) ducted modes propagating through the middle atmosphere that leak back into the thermosphere, and (4) GWs reflected from the Earth's surface that reach the thermosphere in a narrow propagation cone. Well-defined spectral features characterize these wave modes in the TF to provide analytical understanding. We propose the TFM as a tool for simulating GW in the mesosphere and in particular the features observed in Polar Mesospheric Clouds (PMC). With present-day computers, it takes less than one hour to compute the TF, so that there is virtually no practical limitation on the source configurations that can be applied and tested in the lower atmosphere. And there is no limitation on the temporal and spatial resolutions the model simulations can provide. We shall discuss the concept and organization of the TFM and present samples of GW simulations that illustrate the capabilities of the model and its user interface. We shall discuss in particular the waves that leak into the mesopause from the thermosphere above and propagate into the region from tropospheric weather systems below.

Porter, H.; Mayr, H.; Moore, J.; Wilson, S.; Armaly, A.

2008-12-01

388

Working With the Wave Equation in Aeroacoustics: The Pleasures of Generalized Functions  

NASA Technical Reports Server (NTRS)

The theme of this paper is the applications of generalized function (GF) theory to the wave equation in aeroacoustics. We start with a tutorial on GFs with particular emphasis on viewing functions as continuous linear functionals. We next define operations on GFs. The operation of interest to us in this paper is generalized differentiation. We give many applications of generalized differentiation, particularly for the wave equation. We discuss the use of GFs in finding Green s function and some subtleties that only GF theory can clarify without ambiguities. We show how the knowledge of the Green s function of an operator L in a given domain D can allow us to solve a whole range of problems with operator L for domains situated within D by the imbedding method. We will show how we can use the imbedding method to find the Kirchhoff formulas for stationary and moving surfaces with ease and elegance without the use of the four-dimensional Green s theorem, which is commonly done. Other subjects covered are why the derivatives in conservation laws should be viewed as generalized derivatives and what are the consequences of doing this. In particular we show how we can imbed a problem in a larger domain for the identical differential equation for which the Green s function is known. The primary purpose of this paper is to convince the readers that GF theory is absolutely essential in aeroacoustics because of its powerful operational properties. Furthermore, learning the subject and using it can be fun.

Farassat, F.; Brentner, Kenneth S.; Dunn, mark H.

2007-01-01

389

On the Hawking Turok solution to the Open Universe wave function  

E-print Network

Hawking and Turok have recently published a solution to the WKB "wave-function for the universe" which they claim leads in a natural way to an open universe as the end point of the evolution for a universe dominated by a scalar field. They furthermore argue that their solution a preferred solution under the rules of the game. This paper will, I hope, clarify their solution and the limits of validity of their argument.

W. Unruh

1998-03-13

390

A rigorous theory of Dicke superradiation - Bethe wave functions in a model with discrete atoms  

NASA Astrophysics Data System (ADS)

The complete integrability of a quantum model of Dicke superradiation with discrete atoms is demonstrated. Bethe wave functions of the system are set up over infinite and finite intervals. A general expression is obtained for the probability of the decay of the initial excited state of the atomic subsystem into eigenstates of the model. The transition to a previously (Rupasov, 1982) studied model of a continuous medium is traced.

Rupasov, V. I.; Iudson, V. I.

1984-03-01

391

Asymptotic Form of Zero Energy Wave Functions in Supersymmetric Matrix Models  

Microsoft Academic Search

We derive the power law decay, and asymptotic form, of SU(2) x Spin(d)\\u000ainvariant wave-functions which are zero-modes of all s_d=2(d-1) supercharges of\\u000areduced (d+1)-dimensional supersymmetric SU(2) Yang Mills theory, resp. of the\\u000aSU(2)-matrix model related to supermembranes in d+2 dimensions.

Jens Hoppe; G. M. Graf; D. Hasler; S.-T. Yau

2000-01-01

392

Wave function of the Universe in the early stage of its evolution  

Microsoft Academic Search

In quantum cosmological models, constructed in the framework of Friedmann–Robertson–Walker metrics, a nucleation of the Universe\\u000a with its further expansion is described as a tunneling transition through an effective barrier between regions with small\\u000a and large values of the scale factor a at non-zero (or zero) energy. The approach for describing this tunneling consists of constructing a wave function satisfying

Sergei P. Maydanyuk

2008-01-01

393

Generalized prolate spheroidal wave functions for optical finite fractional Fourier and linear canonical transforms  

Microsoft Academic Search

Prolate spheroidal wave functions (PSWFs) are known to be useful for analyzing the properties of the finite-extension Fourier transform (fi-FT). We extend the theory of PSWFs for the finite-extension fractional Fourier transform, the finite-extension linear canonical transform, and the finite-extension offset linear canonical transform. These finite transforms are more flexible than the fi-FT and can model much more generalized optical

Soo-Chang Pei; Jian-Jiun Ding

2005-01-01

394

SSA realization in UWB multiple access systems based on prolate spheroidal wave functions  

Microsoft Academic Search

With respect to soft-spectrum adaptation (SSA) UWB wireless system with multiband pulse waveform shaping and adaptation, we investigate a design scheme for pulse waveform optimization based on prolate spheroidal wave functions (PSWF). The PSWF-based pulse shaping is then applied to M-ary signaling for high data rate and multiple accessing environment expected by multiuser services. Moreover, double water-filling (DWF) method is

Honggang Zhang; Ryuji KOHNO

2004-01-01

395

Emergence of complex and spinor wave functions in scale relativity. I. Nature of scale variables  

SciTech Connect

One of the main results of scale relativity as regards the foundation of quantum mechanics is its explanation of the origin of the complex nature of the wave function. The scale relativity theory introduces an explicit dependence of physical quantities on scale variables, founding itself on the theorem according to which a continuous and non-differentiable space-time is fractal (i.e., scale-divergent). In the present paper, the nature of the scale variables and their relations to resolutions and differential elements are specified in the non-relativistic case (fractal space). We show that, owing to the scale-dependence which it induces, non-differentiability involves a fundamental two-valuedness of the mean derivatives. Since, in the scale relativity framework, the wave function is a manifestation of the velocity field of fractal space-time geodesics, the two-valuedness of velocities leads to write them in terms of complex numbers, and yields therefore the complex nature of the wave function, from which the usual expression of the Schrödinger equation can be derived.

Nottale, Laurent; Célérier, Marie-Noëlle [LUTH, Observatoire de Paris, CNRS, Université Paris-Diderot, 5 place Jules Janssen, 92195 Meudon Cedex (France)] [LUTH, Observatoire de Paris, CNRS, Université Paris-Diderot, 5 place Jules Janssen, 92195 Meudon Cedex (France)

2013-11-15

396

Crustal shear-wave velocity structure beneath northeast India from teleseismic receiver function analysis  

NASA Astrophysics Data System (ADS)

We investigated the seismic shear-wave velocity structure of the crust beneath nine broadband seismological stations of the Shillong-Mikir plateau and its adjoining region using teleseismic P-wave receiver function analysis. The inverted shear wave velocity models show ?34-38 km thick crust beneath the Shillong Plateau which increases to ?37-38 km beneath the Brahmaputra valley and ?46-48 km beneath the Himalayan foredeep region. The gradual increase of crustal thickness from the Shillong Plateau to Himalayan foredeep region is consistent with the underthrusting of Indian Plate beyond the surface collision boundary. A strong azimuthal variation is observed beneath SHL station. The modeling of receiver functions of teleseismic earthquakes arriving the SHL station from NE backazimuth (BAZ) shows a high velocity zone within depth range 2-8 km along with a low velocity zone within ?8-13 km. In contrast, inversion of receiver functions from SE BAZ shows high velocity zone in the upper crust within depth range ?10-18 km and low velocity zone within ?18-36 km. The critical examination of ray piercing points at the depth of Moho shows that the rays from SE BAZ pierce mostly the southeast part of the plateau near Dauki fault zone. This observation suggests the effect of underthrusting Bengal sediments and the underlying oceanic crust in the south of the plateau facilitated by the EW-NE striking Dauki fault dipping 300 toward northwest.

Bora, Dipok K.; Hazarika, Devajit; Borah, Kajaljyoti; Rai, S. S.; Baruah, Saurabh

2014-08-01

397

The energy levels and the corresponding normalized wave functions for a model of a compressed atom  

NASA Astrophysics Data System (ADS)

In the model of a compressed atom (or ion) considered in the present paper the boundary condition associated with the corresponding uncompressed atom, i.e., the condition that the radial wave function must vanish at r=?, is replaced by the boundary condition that the radial wave function must have a node at the finite distance r=a. The treatment of the problem of obtaining the energy shift due to the compression is based on the phase-integral method developed by Fröman and Fröman, an essential feature of which is that one can use exact formulas in the calculations and make all approximations in the final stage. The treatment of the problem of obtaining the relative change of the wave function due to the compression is based on the rigorous evaluation of the normalization integral developed by Furry [Phys. Rev. 71, 360 (1947)] and Yngve [J. Math. Phys. 13, 324 (1972)], in which one also uses exact formulas in the calculations and makes all approximations in the final stage. Since compression of an atom gives rise to very subtle effects, rigorous methods are indispensible for obtaining accurate and reliable analytical final formulas. As an application, the resulting general formulas are particularized to the case of a hydrogenic atom, and a numerical illustration of the accuracy of the formulas is given.

Fröman, Per Olof; Yngve, Staffan; Fröman, Nanny

1987-08-01

398

Structure of the Particle-Hole Amplitudes in No-core Shell Model Wave Functions  

E-print Network

We study the structure of the no-core shell model wave functions for $^6$Li and $^{12}$C by investigating the ground state and first excited state electron scattering charge form factors. In both nuclei, large particle-hole ($ph$) amplitudes in the wave functions appear with the opposite sign to that needed to reproduce the shape of the $(e,e')$ form factors, the charge radii, and the B(E2) values for the lowest two states. The difference in sign appears to arise mainly from the monopole $\\Delta\\hbar\\omega=2$ matrix elements of the kinetic and potential energy (T+V) that transform under the harmonic oscillator SU(3) symmetries as $(\\lambda,\\mu)=(2,0)$. These are difficult to determine self-consistently, but they have a strong effect on the structure of the low-lying states and on the giant monopole and quadrupole resonances. The Lee-Suzuki transformation, used to account for the restricted nature of the space in terms of an effective interaction, introduces large higher-order $\\Delta\\hbar\\omega=n, n>$2, $ph$ amplitudes in the wave functions. The latter $ph$ excitations aggravate the disagreement between the experimental and predicted $(e,e')$ form factors with increasing model spaces, especially at high momentum transfers. For sufficiently large model spaces the situation begins to resolve itself for $^6$Li, but the convergence is slow. A prescription to constrain the $ph$ excitations would likely accelerate convergence of the calculations.

A. C. Hayes; A. A. Kwiatkowski

2009-08-06

399

Indexes to anticipate negative impacts of heat waves in urban Mediterranean environments  

NASA Astrophysics Data System (ADS)

This study intention is to understand what might be the better indexes to anticipate health deterioration during temperature extreme events in a urban Mediterranean environment like Porto. To do this we look to the effects of the July 2006 Heat Wave using the Heat Index on the Mortality (All Causes) and Morbidity (All Causes, Respiratory and Circulatory diseases) in general, and in people over 74 years and by Gender, in Porto. The Poisson Generalized Additive Regression model was used in order to estimate the impact of Apparent Temperature (Heat Index) and Daily Mortality and Morbidity during the July 2006 Heat Wave. Daily Mortality, Morbidity and Heat Index was correlated with lags of Apparent Temperature up to 7 days using Pearson correlation. For a 1°C increase in mean Apparent Temperature we observed a 2.7% (95%CI:1.7-3.6%) increase in Mortality (for All Causes), 1.7% (95%CI:0.6-2.9%) in Respiratory Morbidity, 2,2% (95%CI:0.4-4.1%) in Women Respiratory Morbidity, 5,4% (95%CI:1.1-6.6%) in Chronic Obstructive Pulmonary Morbidity and 7,5% (95%CI:1.3-14.1%) in Women Chronic Obstructive Pulmonary Morbidity, for the entire population. For people ? 75 years, our work showed a 3,3% increase (95%CI:1.7-5.0%) in Respiratory Morbidity, 2,7% (95%CI:0.4-5.1%) in Men Respiratory Morbidity, 3,9% (95%CI:1.6-6.3%) in Women Respiratory Morbidity, 7.0% (95%CI:1.1-13.2%) in Chronic Obstructive Pulmonary Disease and 9.0% (95%CI:0.3-18.5%) in Women Chronic Obstructive Pulmonary Disease. We conclude that the use of Heat Index in a Mediterranean Tempered Climate enabled the identification of the effects of the July 2006 Heat Wave in Mortality due to All Causes and in Respiratory Morbidity of the General Population, as well as in Respiratory Morbidity of individuals with more than 74 years of age.

Monteiro, A. M.; Carvalho, C. V.; Velho, S. V.; Sousa, C. S.

2012-04-01

400

Towards the explicit computation of Bohm velocities associated to N-electron wave-functions with arbitrary spin-orientations  

E-print Network

The direct solution of the many-particle Schr\\"odinger equation is computationally inaccessible for more than very few electrons. In order to surpass this limitation, one of the authors [X. Oriols, Phys. Rev. Lett. 2007, 98 (066803)] has recently proposed a new model to study electron-electron correlations from Bohm trajectories associated to time-dependent wave-packets solutions of pseudo single-particle Schr\\"odinger equations. In the aforementioned paper only the orbital exchange interaction is considered assuming that all electrons have the same spin orientation. Then, the many-particle wave function is a complex Slater determinant of the single-particle wave-packets. In the present work the previous formalism is extended to study many-particle wave functions where the electrons have different spin orientations.The main difficulty to treat N different electron spin orientations with time-dependent wave-packets is that one must study all the possible N!N! products of permutations among spin states. To overcome this computationally inaccessible problem, in this article the total wave function is treated as a separated product of two many-particle wave functions, the first with spin up and the second with spin down. In order to numerically justify this approximation, the Bohm velocity in different antisymmetric total wave-function scenarios is computed. The computational results confirms the accurate validity of our approximation under a large number of cases.

A. Alarcon; X. Cartoixa; X. Oriols

2014-08-19

401

Wave function of the Universe and Chern-Simons Perturbation Theory  

E-print Network

The Chern-Simons exact solution of four-dimensional quantum gravity with nonvanishing cosmological constant is presented in metric variable as the partition function of a Chern-Simons theory with nontrivial source. The perturbative expansion is given, and the wave function is computed to the lowest order of approximation for the Cauchy surface which is topologically a 3-sphere. The state is well-defined even at degenerate and vanishing values of the dreibein. Reality conditions for the Ashtekar variables are also taken into account; and remarkable features of the Chern-Simons state and their relevance to cosmology are pointed out.

Chopin Soo

2002-02-28

402

Acoustic wave propagation in continuous functionally graded plates: an extension of the Legendre polynomial approach.  

PubMed

The propagation of guided waves in continuous functionally graded plates is studied by using Legendre polynomials. Dispersion curves, and power and field profiles are easily obtained. Our computer program is validated by comparing our results against other calculations from the literature. Numerical results are also given for a graded semiconductor plate. It is felt that the present method could be of quite practical interest in waveguiding engineering, non-destructive testing of functionally graded materials (FGMs) to identify the best inspection strategies, or by means of a numerical inversion algorithm to determine through-thickness gradients in material parameters. PMID:11570758

Lefebvre, J E; Zhang, V; Gazalet, J; Gryba, T; Sadaune, V

2001-09-01

403

Negative Impacts of Human Land Use on Dung Beetle Functional Diversity  

Microsoft Academic Search

The loss of biodiversity caused by human activity is assumed to alter ecosystem functioning. However our understanding of the magnitude of the effect of these changes on functional diversity and their impact on the dynamics of ecological processes is still limited. We analyzed the functional diversity of copro-necrophagous beetles under different conditions of land use in three Mexican biosphere reserves.

Felipe Barragán; Claudia E. Moreno; Federico Escobar; Gonzalo Halffter; Dario Navarrete; Brock Fenton

2011-01-01

404

On the longitudinal response function of interferometers for massive gravitational waves from a bimetric theory of gravity  

E-print Network

Recently, some papers in the literature have shown that, from a bimetric theory of gravity, it is possible to produce massive gravitational waves which generate a longitudinal component in a particular polarization of the wave. After a review of previous works, in this paper the longitudinal response function of interferometers for this particular polarization of the wave is computed in two different gauges, showing the gauge invariance, and in its full frequency dependence, with specific application to the Virgo and LIGO interferometers.

Christian Corda

2008-07-31

405

Convergence of many-body wave-function expansions using a plane-wave basis: From homogeneous electron gas to solid state systems  

NASA Astrophysics Data System (ADS)

Using the finite simulation-cell homogeneous electron gas (HEG) as a model, we investigate the convergence of the correlation energy to the complete-basis-set (CBS) limit in methods utilizing plane-wave wave-function expansions. Simple analytic and numerical results from second-order Møller-Plesset theory (MP2) suggest a 1/M decay of the basis-set incompleteness error where M is the number of plane waves used in the calculation, allowing for straightforward extrapolation to the CBS limit. As we shall show, the choice of basis-set truncation when constructing many-electron wave functions is far from obvious, and here we propose several alternatives based on the momentum transfer vector, which greatly improve the rate of convergence. This is demonstrated for a variety of wave-function methods, from MP2 to coupled-cluster doubles theory and the random-phase approximation plus second-order screened exchange. Finite basis-set energies are presented for these methods and compared with exact benchmarks. A transformation can map the orbitals of a general solid state system onto the HEG plane-wave basis and thereby allow application of these methods to more realistic physical problems. We demonstrate this explicitly for solid and molecular lithium hydride.

Shepherd, James J.; Grüneis, Andreas; Booth, George H.; Kresse, Georg; Alavi, Ali

2012-07-01

406

Progress at the interface of wave-function and density-functional theories  

SciTech Connect

The Kohn-Sham (KS) potential of density-functional theory (DFT) emerges as the minimizing effective potential in a variational scheme that does not involve fixing the unknown single-electron density. Using Rayleigh Schroedinger (RS) perturbation theory (PT), we construct ab initio approximations for the energy difference, the minimization of which determines the KS potential directly - thereby bypassing DFT's traditional algorithm to search for the density that minimizes the total energy. From second-order RS PT, we obtain variationally stable energy differences to be minimized, solving the severe problem of variational collapse of orbital-dependent exchange-correlation functionals based on second-order RS PT.

Gidopoulos, Nikitas I. [ISIS, Rutherford Appleton Laboratory, STFC, Didcot, OX11 0QX, Oxon (United Kingdom)

2011-04-15

407

Generalized theory of resonance scattering (GTRS) using the translational addition theorem for spherical wave functions.  

PubMed

The generalized theory of resonance scattering (GTRS) by an elastic spherical target in acoustics is extended to describe the arbitrary scattering of a finite beam using the addition theorem for the spherical wave functions of the first kind under a translation of the coordinate origin. The advantage of the proposed method over the standard discrete spherical harmonics transform previously used in the GTRS formalism is the computation of the off-axial beam-shape coefficients (BSCs) stemming from a closed-form partial-wave series expansion representing the axial BSCs in spherical coordinates. With this general method, the arbitrary acoustical scattering can be evaluated for any particle shape and size, whether the particle is partially or completely illuminated by the incident beam. Numerical examples for the axial and off-axial resonance scattering from an elastic sphere placed arbitrarily in the field of a finite circular piston transducer with uniform vibration are provided. Moreover, the 3-D resonance directivity patterns illustrate the theory and reveal some properties of the scattering. Numerous applications involving the scattering phenomenon in imaging, particle manipulation, and the characterization of multiphase flows can benefit from the present analysis because all physically realizable beams radiate acoustical waves from finite transducers as opposed to waves of infinite extent. PMID:25389166

Mitri, Farid

2014-11-01

408

Acute effect of alcohol intake on sine-wave Cartesian and polar contrast sensitivity functions  

PubMed Central

The aim of this study was to assess contrast sensitivity for angular frequency stimuli as well as for sine-wave gratings in adults under the effect of acute ingestion of alcohol. We measured the contrast sensitivity function (CSF) for gratings of 0.25, 1.25, 2.5, 4, 10, and 20 cycles per degree of visual angle (cpd) as well as for angular frequency stimuli of 1, 2, 4, 24, 48, and 96 cycles/360°. Twenty adults free of ocular diseases, with normal or corrected-to-normal visual acuity, and no history of alcoholism were enrolled in two experimental groups: 1) no alcohol intake (control group) and 2) alcohol ingestion (experimental group). The average concentration of alcohol in the experimental group was set to about 0.08%. We used a paradigm involving a forced-choice method. Maximum sensitivity to contrast for sine-wave gratings in the two groups occurred at 4 cpd sine-wave gratings and at 24 and 48 cycles/360° for angular frequency stimuli. Significant changes in contrast sensitivity were observed after alcohol intake compared with the control condition at spatial frequency of 4 cpd and 1, 24, and 48 cycles/360° for angular frequency stimuli. Alcohol intake seems to affect the processing of sine-wave gratings at maximum sensitivity and at the low and high frequency ends for angular frequency stimuli, both under photopic luminance conditions. PMID:24676473

Cavalcanti-Galdino, M.K.; da Silva, J.A.; Mendes, L.C.; dos Santos, N.A.; Simas, M.L.B.

2014-01-01

409

Plane-wave superpositions defined by orthonormal scalar functions on two- and three-dimensional manifolds  

PubMed

Vector plane-wave superpositions defined by a given set of orthonormal scalar functions on a two- or three-dimensional manifold-beam manifold-are treated. We present a technique for composing orthonormal beams and some other specific types of fields such as three-dimensional standing waves, moving and evolving whirls. It can be used for any linear fields, in particular, electromagnetic fields in complex media and elastic fields in crystals. For electromagnetic waves in an isotropic medium or free space, unique families of exact solutions of Maxwell's equations are obtained. The solutions are illustrated by calculating fields, energy densities, and energy fluxes of beams defined by the spherical harmonics. It is shown that the obtained results can be used for a transition from the plane-wave approximation to more accurate models of real incident beams in free-space techniques for characterizing complex media. A mathematical formalism convenient for the treatment of various beams defined by the spherical harmonics is presented. PMID:11088246

Borzdov

2000-04-01

410

Radial and angular correlations of two excited electrons. III. Comparison of configuration-interaction wave functions with adiabatic channel functions in hyperspherical coordinates  

NASA Astrophysics Data System (ADS)

Wave functions for doubly excited states of helium 1,3Se states calculated in the configuration-interaction (CI) method are examined in hyperspherical coordinates. It is shown that these wave functions are essentially identical to the wave functions calculated in the adiabatic approximation except in regions where the charge density is vanishingly small. This comparison establishes the connection between the classification of doubly excited states based upon the adiabatic approximation in hyperspherical coordinates and the classification of Herrick and Sinanogl? which is based upon the approximate CI wave functions. It is also shown that states calculated from the CI method which have similar quantum defects have the same correlation patterns except in regions where the charge density is small. This establishes the approximate channel classification of doubly excited states as implied in the adiabatic approximation in hyperspherical coordinates.

Lin, C. D.

1983-01-01

411

Performance analysis of incoherent multi-wavelength OCDMA systems under the impact of four-wave mixing.  

PubMed

In this paper, we comprehensively analyze the impact of four wave mixing (FWM) on the performance of incoherent multi-wavelength optical code-division multiple-access (MW-OCDMA) systems. We also consider many other interferences and noises, including multiple access interference, optical beating interference, and receiver noise, in the analysis. From the numerical results, we can find the power ranges of different MW-OCDMA systems, in which the impact of FWM is dominant and consequently results in an increase in the bit-error rate of the systems. We also find that the impact of FWM becomes more severe when the frequency spacing is small and/or dispersion-shifted fiber is used. In addition, we quantitatively discuss the impact of FWM on the number of supportable users and power penalty in the MW-OCDMA systems. PMID:20588844

Dang, Ngoc T; Pham, Anh T

2010-05-10

412

The wave function and minimum uncertainty function of the bound quadratic Hamiltonian system  

NASA Technical Reports Server (NTRS)

The bound quadratic Hamiltonian system is analyzed explicitly on the basis of quantum mechanics. We have derived the invariant quantity with an auxiliary equation as the classical equation of motion. With the use of this invariant it can be determined whether or not the system is bound. In bound system we have evaluated the exact eigenfunction and minimum uncertainty function through unitary transformation.

Yeon, Kyu Hwang; Um, Chung IN; George, T. F.

1994-01-01

413

Impact of Cerebrovascular Risk Factors on Brain Function and Structure in HIV-infected Individuals  

E-print Network

(HAART). Traditional CVD risk factors such as dyslipidemia, hypertension, diabetes, and smoking are highImpact of Cerebrovascular Risk Factors on Brain Function and Structure in HIV-infected Individuals in this population. To date, the impact of CVD risk factors on cognition in the HIV infected population has not been

Thompson, Paul

414

Binding Energy of d¹º Transition Metals to Alkenes By Wave Function Theory and Density Functional Theory  

SciTech Connect

The structures of Pd(PH?)? and Pt(PH?) ? complexes with ethene and conjugated CnHn?? systems (n=4, 6, 8, and 10) were studied. Their binding energies were calculated using both wave function theory (WFT) and density functional theory (DFT). Previously it was reported that the binding energy of the alkene to the transition metal does not depend strongly on the size of the conjugated CnHn+2 ligand, but that DFT methods systematically underestimate the binding energy more and more significantly as the size of the conjugated system is increased. Our results show that recently developed density functionals predict the binding energy for these systems much more accurately. New benchmark calculations carried out by the coupled cluster method based on Brueckner orbitals with double excitations and a quasiperturbative treatment of connected triple excitations (BCCD(T)) with a very large basis set agree even better with the DFT predictions than do the previous best estimates. The mean unsigned error in absolute and relative binding energies of the alkene ligands to Pd(PH?)? is 2.5 kcal/mol for the ?B97 and M06 density functionals and 2.9 kcal/mol for the M06-L functional. Adding molecular mechanical damped dispersion yields even smaller mean unsigned errors: 1.3 kcal/mol for the M06-D functional, 1.5 kcal/mol for M06- L-D, and 1.8 kcal/mol for B97-D and ?B97X-D. The new functionals also lead to improved accuracy for the analogous Pt complexes. These results show that recently developed density functionals may be very useful for studying catalytic systems involving Pd d¹º centers and alkenes.

Averkiev, Boris B.; Zhao, Yan; Truhlar, Donald G.

2010-06-01

415

High-Speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-On Impact (EOI) Method  

SciTech Connect

An Edge-on Impact (EOI) technique, developed at the Ernst-Mach-Institute (EMI), coupled with a Cranz-Schardin high-speed camera, has been successfully utilized to visualize dynamic fracture in many brittle materials. In a typical test, the projectile strikes one edge of a specimen and damage formation and fracture propagation is recorded during the first 20 {mu}s after impact. In the present study, stress waves and damage propagation in fused silica and AlON were examined by means of two modified Edge-on Impact arrangements. In one arrangement, fracture propagation was observed simultaneously in side and top views of the specimens by means of two Cranz-Schardin cameras. In another arrangement, the photographic technique was modified by placing the specimen between crossed polarizers and using the photo-elastic effect to visualize the stress waves. Pairs of impact tests at approximately equivalent velocities were carried out in transmitted plane (shadowgraphs) and crossed polarized light.

Strassburger, E. [Fraunhofer-Institut fuer Kurzzeitdynamik, Ernst-Mach-Institut (EMI), Am Klingelberg 1, 79588 Efringen-Kirchen (Germany); Patel, P.; McCauley, J. W. [US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Templeton, D. W. [US Army TARDEC, Warren, MI (United States)

2006-07-28

416

Study of Kinematics of Extreme Waves Impacting Offshore and Coastal Structures by Non Intrusive Measurement Techniques  

E-print Network

, multiphase wave flow velocities during active interactions with various offshore and onshore ocean environments. First, initial inundation flow structures of tsunami-like long waves interacting with complex coastal topography are experimentally...

Song, Youn Kyung

2013-11-07

417

Impact of Common KIBRA Allele on Human Cognitive Functions  

Microsoft Academic Search

The rs17070145 polymorphism (C ? T substitution, intron 9) of the KIBRA gene has recently been associated with episodic memory and cognitive flexibility. These findings were inconsistent across reports though, and largely lacked gene–gene or gene–environment interactions. The aim of the present study was to determine the impact of the rs17070145 polymorphism on clinically relevant cognitive domains and its interaction

H Wersching; K Guske; S Hasenkamp; C Hagedorn; S Schiwek; S Jansen; V Witte; J Wellmann; H Lohmann; K Duning; J Kremerskothen; S Knecht; E Brand; A Floel

2011-01-01

418

On de Broglie's soliton wave function of many particles with finite masses, energies and momenta  

E-print Network

We consider a mass-less manifestly covariant {\\it linear} Schr\\"odinger equation. First, we show that it possesses a class of non-dispersive soliton solution with finite-size spatio-temporal support inside which the quantum amplitude satisfies the Klein-Gordon equation with finite {\\it emergent} mass. We then proceed to interpret the soliton wave function as describing a particle with finite mass, energy and momentum. Inside the spatio-temporal support, the wave function shows spatio-temporal internal vibration with angular frequency and wave number that are determined by the energy-momentum of the particle as firstly conjectured by de Broglie. Imposing resonance of the internal vibration inside the spatio-temporal support leads to Planck-Einstein quantization of energy-momentum. The first resonance mode is shown to recover the classical energy-momentum relation developed in special relativity. We further show that the linearity of the Schr\\"odinger equation allows one to construct many solitons solution through superposition, each describing a particle with various masses, energies and momenta.

Agung Budiyono

2009-08-19

419

Global propagation of gravity waves generated with the whole atmosphere transfer function model  

NASA Astrophysics Data System (ADS)

A brief review is presented of the Transfer Function Model (TFM) [e.g., Mayr et al., Space Science Reviews, 1990], which describes acoustic gravity waves (AGW) that propagate across the globe in a dissipative and static (no winds) background atmosphere with globally uniform temperature and density variations extending from the ground to 700 km. Unique among existing models, the TFM can be placed between the analytical approach on one end, and the rigorous numerical approach of general circulation models (GCM). The time consuming numerical integration of the conservation equations is restricted to compute the transfer function (TF) for a broad range of frequencies and spherical harmonics. Given TF, the atmospheric response for a chosen source configuration is then obtained in short order. Computationally efficient, the model is well suited to serve as experimental and educational tool for simulating propagating wave patterns across the globe. By design, the TFM is also semi-analytical and therefore well suited to explore the different wave modes that can be generated under different dynamical conditions.

Mayr, Hans G.; Talaat, Elsayed R.; Wolven, Brian C.

2013-11-01

420

Climate extremes in urban area and their impact on human health: the summer heat waves  

NASA Astrophysics Data System (ADS)

In the period 1951-2012 the average global land and ocean temperature has increased by approximately 0.72°C [0.49-0.89] when described by a linear trend, and is projected to rapidly increase. Each of the past three decades has been warmer than all the previous decades, with the decade of the 2000's as the warmest, and, since 1880, nine of the ten warmest years are in the 21st century, the only exception being 1998, which was warmed by the strongest El Niño event of the past century. In parallel an increase in the frequency and intensity of extremely hot days is detected with differences at different scales, which represent an health risk specially in largely populated areas as documented for several regions in the world including the Euro-Mediterranean region. If it is still under discussion if heat wave episodes are a direct result of the warming of the lower troposphere, or if, more likely, they are a regional climate event, however heat episodes have been studied in order to define their correlation with large scale atmospheric patterns and with changes in the regional circulation. Whatever the causes and the spatio-temporal extension of the episodes, epidemiological studies show that these conditions pose increasing health risks inducing heat-related diseases including hyperthermia and heat stress, cardiovascular and respiratory illnesses in susceptible individuals with a significant increase in morbidity and mortality especially in densely populated urban areas. In several Mediterranean cities peaks of mortality associated with extremely high temperature (with simultaneous high humidity levels) have been documented showing that, in some cases, a large increase in daily mortality has been reached compared to the average for the period. The number of fatalities during the summer 2003 heat wave in Europe was estimated to largely exceed the average value of some between 22000 and 50000 cases. In the same summer it was also unusually hot across much of Asia, and Shanghai, which is particularly prone to heat waves, recorded the hottest summer in over 50 years. During the event, the maximum number of daily deaths was 317, 42% above the non-heat day average, even though an heat warning system in operation. In this study results from the analysis of heat waves events in Italian cities is presented. Indices representative of extremely hot conditions have been taken into account and results of the analysis of indices such as the number of summer days (SU), number of tropical nights (TR), maxima and minima of daily maximum and minimum temperatures (TXx, TXn, TNx, TNn, respectively), exceedances over fixed thresholds is presented. Results show a clear increase in the past decades of the numbers of days affected by heat events. Some considerations are also presented about the impact on human health of the longest events occurred in the Country.

Baldi, Marina

2014-05-01

421

The Impact of Defects on Q0 for HIE-ISOLDE High-Beta Quarter-Wave Resonators  

E-print Network

Superconducting quarter-wave resonators (QWRs) will be used in the SC linac for the HIE-ISOLDE project at CERN. The QWRs will be working at 4.5 K with an operating frequency of 101.28 MHz. The maximum dissipated power in the cavity is required to be 10 W at a gradient of 6 MV/m. The QWRs are niobium coated on copper substrates, thus the niobium film quality has a direct impact on the cavity performance. This note calculates the impact of defects on cavity Q0 at different locations on the cavity inner surface.

Zhang, P; Venturini Delsolari, W

2014-01-01

422

Impact of Basset force on threshold values of particle drag coefficient and density parameter in standing sinusoidal wave  

NASA Astrophysics Data System (ADS)

A one-dimensional drift of spherical particle in standing sinusoidal wave is studied numerically. The impact of stationary and non-stationary forces of viscous drag, as well as Archimedes, added masses and Basset forces on particle drift direction is investigated. For various Reynolds and Strouhal numbers the dependencies of the threshold particle drag coefficient on density parameter have been found. These dependencies show that with increasing Reynolds and Strouhal numbers the threshold value of the squared drag coefficient decreases markedly. Impact of Basset force on threshold values is especially strong for low- density particles.

Gubaidullin, D. A.; Osipov, P. P.; Zakirov, A. N.

2014-11-01

423

Effect of extracorporeal shock wave therapy on denervation atrophy and function caused by sciatic nerve injury.  

PubMed

[Purpose] The present study examined the effects of treatment using extracorporeal shock wave therapy (ESWT) on the muscle weight and function of the hind limb in sciatic nerve injury. [Subjects] Forty rats with sciatic nerve crushing injury were randomly divided into two groups: an ESWT group (n=20), and a control group (n=20). [Methods] The ESWT group received extracorporeal shock wave treatment, and the control group did not receive any treatment after injury. Experimental animals were measured for muscle weight on an electronic scale and were tested for function on a sciatic functional index (SFI). [Results] All groups showed significant increases in the weights of the left soleus and gastrocnemius muscles, and decreases in the weights of the right soleus and gastrocnemius muscles (p<0.05). Comparison of SFI scores and muscle weights between the groups showed significant differences in SFI scores, and the right soleus and gastrocnemius muscles (p<0.05) [Conclusion] Exercise programs that use ESWT can be said to be effective at improving the function of the sciatic nerve and preventing the denervation atrophy. PMID:24259917

Lee, Jung-Ho; Cho, Sung-Hyoun

2013-09-01

424

Shock Wave Impact on Weak Concrete , K.D. Gardner1  

E-print Network

to a structure from blast waves [1]. The best way to protect an existing structure is hardening like building/19, Moscow, Russia Abstract. A blast wave front possesses characteristics similar to a shock wave created in a shock tube and a reasonably realistic simulation of bomb blast loading on structures can be made using

Texas at Arlington, University of

425

Joint inversion of surface wave dispersion and receiver functions: a Bayesian Monte-Carlo approach  

NASA Astrophysics Data System (ADS)

A non-linear Bayesian Monte-Carlo method is presented to estimate a Vsv model beneath stations by jointly interpreting Rayleigh wave dispersion and receiver functions and associated uncertainties. The method is designed for automated application to large arrays of broad-band seismometers. As a testbed for the method, 185 stations from the USArray Transportable Array are used in the Intermountain West, a region that is geologically diverse and structurally complex. Ambient noise and earthquake tomography are updated by applying eikonal and Helmholtz tomography, respectively, to construct Rayleigh wave dispersion maps from 8 to 80 s across the study region with attendant uncertainty estimates. A method referred to as `harmonic stripping method' is described and applied as a basis for quality control and to generate backazimuth independent receiver functions for a horizontally layered, isotropic effective medium with uncertainty estimates for each station. A smooth parametrization between (as well as above and below) discontinuities at the base of the sediments and crust suffices to fit most features of both data types jointly across most of the study region. The effect of introducing receiver functions to surface wave dispersion data is quantified through improvements in the posterior marginal distribution of model variables. Assimilation of receiver functions quantitatively improves the accuracy of estimates of Moho depth, improves the determination of the Vsv contrast across Moho, and improves uppermost mantle structure because of the ability to relax a priori constraints. The method presented here is robust and can be applied systematically to construct a 3-D model of the crust and uppermost mantle across the large networks of seismometers that are developing globally, but also provides a framework for further refinements in the method.

Shen, Weisen; Ritzwoller, Michael H.; Schulte-Pelkum, Vera; Lin, Fan-Chi

2013-02-01

426