Pan Xiaoyin; Slamet, Marlina; Sahni, Viraht
2010-04-15
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.
Holographic tunneling wave function
NASA Astrophysics Data System (ADS)
Conti, Gabriele; Hertog, Thomas; van der Woerd, Ellen
2015-12-01
The Hartle-Hawking wave function in cosmology can be viewed as a decaying wave function with anti-de Sitter (AdS) boundary conditions. We show that the growing wave function in AdS familiar from Euclidean AdS/CFT is equivalent, semiclassically and up to surface terms, to the tunneling wave function in cosmology. The cosmological measure in the tunneling state is given by the partition function of certain relevant deformations of CFTs on a locally AdS boundary. We compute the partition function of finite constant mass deformations of the O( N ) vector model on the round three sphere and show this qualitatively reproduces the behaviour of the tunneling wave function in Einstein gravity coupled to a positive cosmological constant and a massive scalar. We find the amplitudes of inhomogeneities are not damped in the holographic tunneling state.
Adaptive multiconfigurational wave functions
Evangelista, Francesco A.
2014-03-28
A method is suggested to build simple multiconfigurational wave functions specified uniquely by an energy cutoff Λ. These are constructed from a model space containing determinants with energy relative to that of the most stable determinant no greater than Λ. The resulting Λ-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 (Λ+SD-CI), which is based on a small Λ-CI reference and adds a selection of all the singly and doubly excited determinants generated from it. We report two heuristic algorithms to build Λ-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 Λ-CI and Λ+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 Λ-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 Λ-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.
Marto, Natália
2005-01-01
During the summer of 2003, record high temperatures were reported across Europe, causing thousands of casualties. Heat waves are sporadic recurrent events, characterised by intense and prolonged heat, associated with excess mortality and morbidity. The most frequent cause of death directly attributable to heat is heat stroke but heat waves are known to cause increases in all-cause mortality, specially circulatory and respiratory mortality. Epidemiological studies demonstrate excess casualties cluster in specific risk groups. The elderly, those with chronic medical conditions and the socially isolated are particularly vulnerable. Air conditioning is the strongest protective factor against heat-related disorders. Heat waves cause disease indirectly, by aggravating chronic disorders, and directly, by causing heat-related illnesses (HRI). Classic HRI include skin eruptions, heat cramps, heat syncope, heat exhaustion and heat stroke. Heat stroke is a medical emergency characterised by hyperthermia and central nervous system dysfunction. Treatment includes immediate cooling and support of organ-system function. Despite aggressive treatment, heat stroke is often fatal and permanent neurological damage is frequent in those who survive. Heat related illness and death are preventable through behavioural adaptations, such as use of air conditioning and increased fluid intake. Other adaptation measures include heat emergency warning systems and intervention plans and environmental heat stress reduction. Heat related mortality is expected to rise as a consequence of the increasing proportion of elderly persons, the growing urban population, and the anticipated increase in number and intensity of heat waves associated with global warming. Improvements in surveillance and response capability may limit the adverse health conditions of future heat waves. It is crucial that health professionals are prepared to recognise, prevent and treat HRI and learn to cooperate with local health agencies. PMID:16684487
Properties of resonance wave functions.
NASA Technical Reports Server (NTRS)
More, R. M.; Gerjuoy, E.
1973-01-01
Construction and study of resonance wave functions corresponding to poles of the Green's function for several illustrative models of theoretical interest. Resonance wave functions obtained from the Siegert and Kapur-Peierls definitions of the resonance energies are compared. The comparison especially clarifies the meaning of the normalization constant of the resonance wave functions. It is shown that the wave functions may be considered renormalized in a sense analogous to that of quantum field theory. However, this renormalization is entirely automatic, and the theory has neither ad hoc procedures nor infinite quantities.
Photoelectron wave function in photoionization: plane wave or Coulomb wave?
Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I
2015-11-19
The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion. PMID:26509428
Vortices in atomic wave functions
NASA Astrophysics Data System (ADS)
Macek, J. H.
2010-02-01
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.
Wave-function functionals for the density
Slamet, Marlina; Pan Xiaoyin; Sahni, Viraht
2011-11-15
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.
Spatial wave functions of photon and electron
Khokhlov, D. L.
2010-12-01
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.
Wave impact on a deck or baffle
NASA Astrophysics Data System (ADS)
Md Noar, Nor Aida Zuraimi; Greenhow, Martin
2015-02-01
Some coastal or ocean structures have deck-like baffles or horizontal platforms that can be exposed to wave action in heavy seas. A similar situation may occur in partially-filled tanks with horizontal baffles that become engulfed by sloshing waves. This can result in dangerous wave impact loads (slamming) causing a rapid rise of pressures which may lead to local damaging by crack initiation and/or propagation. We consider the wave impact against the whole of underside of horizontal deck (or baffle) projecting from a seawall (or vertical tank wall), previously studied by Wood and Peregrine (1996) using a different method based on conformal mappings. The approach used is to simplify the highly time-dependent and very nonlinear problem by considering the time integral of the pressure over the duration of the impact pressure-impulse, P (x, y). Our method expresses this in terms of eigenfunctions that satisfy the boundary conditions apart from that on the impact region and the matching of the two regions (under the platform and under the free surface); this results in a matrix equation to be solved numerically. As in Wood and Peregrine, we found that the pressure impulse on the deck increases when the length of deck increases, there is a strong pressure gradient beneath the deck near the seaward edge and the maximum pressure impulse occurs at the landward end of the impact zone.
Extreme Wave Impact on a Flexible Plate
NASA Astrophysics Data System (ADS)
Abraham, Aliza; Techet, Alexandra
2015-11-01
Digital image correlation (DIC) and particle image velocimetry (PIV) are combined to characterize the flow-structure interaction of a breaking wave impacting a flexible vertically mounted plate. DIC is used with the beam bending equation to determine the stresses on the plate and PIV is used to describe the flow of the wave. In this experiment, a simulated dam break in which water is rapidly released from a reservoir generates the wave, which impinges on a cantilevered stainless steel plate downstream. Pressure sensors mounted on the plate are used to gather further information about the forces acting on it. A series of waves of different heights and breaking locations are tested, controlled by the volume of water in the tank and the volume of water in the dam break reservoir. The deflection of the plate varies depending on the point of breaking and the height of the wave. These results shed light on the effect of breaking wave impacts on offshore structures and ship hulls.
Deuteron wave function and OPE potential
NASA Astrophysics Data System (ADS)
Righi, S.; Rosa-Clot, M.
1987-06-01
The deuteron wave function is calculated integrating from outside the Schredinger equation using as input its asymptotic behaviour. Some potentials are tested and the one pion exchange potential (OPEP) is shown to be the main responsible of the wave function structure up to distances of about 1 fm. The relevance of the short range part of the potential is analyzed and it is shown that a substantial enhancement of the OPEP central part is needed in the deuteron channel.
The geometry of electron wave functions
Aminov, Yurii A
2013-02-28
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.
Weak measurement and Bohmian conditional wave functions
Norsen, Travis; Struyve, Ward
2014-11-15
It was recently pointed out and demonstrated experimentally by Lundeen et al. that the wave function of a particle (more precisely, the wave function possessed by each member of an ensemble of identically-prepared particles) can be “directly measured” using weak measurement. Here it is shown that if this same technique is applied, with appropriate post-selection, to one particle from a perhaps entangled multi-particle system, the result is precisely the so-called “conditional wave function” of Bohmian mechanics. Thus, a plausibly operationalist method for defining the wave function of a quantum mechanical sub-system corresponds to the natural definition of a sub-system wave function which Bohmian mechanics uniquely makes possible. Similarly, a weak-measurement-based procedure for directly measuring a sub-system’s density matrix should yield, under appropriate circumstances, the Bohmian “conditional density matrix” as opposed to the standard reduced density matrix. Experimental arrangements to demonstrate this behavior–and also thereby reveal the non-local dependence of sub-system state functions on distant interventions–are suggested and discussed. - Highlights: • We study a “direct measurement” protocol for wave functions and density matrices. • Weakly measured states of entangled particles correspond to Bohmian conditional states. • Novel method of observing quantum non-locality is proposed.
Stress Wave Source Characterization: Impact, Fracture, and Sliding Friction
NASA Astrophysics Data System (ADS)
McLaskey, Gregory Christofer
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 asperities as well as their failure behavior. With proper scaling, the strong link between material properties and laboratory earthquakes will aid in our understanding of fault mechanics and the generation of earthquakes and seismic tremor.
The Wave Function and Quantum Reality
NASA Astrophysics Data System (ADS)
Gao, Shan
2011-03-01
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.
Measuring the quantum mechanical wave function
NASA Astrophysics Data System (ADS)
Raymer, M. G.
1997-05-01
In the past few years experimenters have learned how to determine the complete quantum state of an ensemble of particles or fields which have been prepared according to some unknown procedure. Through these experiments they have answered a question posed by W. Pauli in the 1930s. The methods used involve measuring statistical distributions of a well chosen set of physical observables and using a tomographic inversion algorithm to reconstruct the Wigner function and its corresponding wave function or density matrix. Recontructions have been successfully carried out in atomic, molecular, and optical physics. The development of these procedures helps to firm up the interpretation of the Schrodinger wave function.
Convergent close coupling versus the generalized Sturmian function approach: Wave-function analysis
NASA Astrophysics Data System (ADS)
Ambrosio, M.; Mitnik, D. M.; Gasaneo, G.; Randazzo, J. M.; Kadyrov, A. S.; Fursa, D. V.; Bray, I.
2015-11-01
We compare the physical information contained in the Temkin-Poet (TP) scattering wave function representing electron-impact ionization of hydrogen, calculated by the convergent close-coupling (CCC) and generalized Sturmian function (GSF) methodologies. The idea is to show that the ionization cross section can be extracted from the wave functions themselves. Using two different procedures based on hyperspherical Sturmian functions we show that the transition amplitudes contained in both GSF and CCC scattering functions lead to similar single-differential cross sections. The single-continuum channels were also a subject of the present studies, and we show that the elastic and excitation amplitudes are essentially the same as well.
Plasmon wave function of graphene nanoribbons
NASA Astrophysics Data System (ADS)
Silveiro, I.; Plaza Ortega, J. M.; García de Abajo, F. J.
2015-08-01
We find the low-frequency optical response of highly doped individual and arrayed graphene nanoribbons to be accurately described in terms of plasmon wave functions (PWFs). More precisely, we focus on the lowest-order transverse dipolar mode, for which we define the wave function as the induced charge density associated with the plasmon. We show that a single universal wave function is capable of describing the normal-incidence interaction of paired, co-planar, and stacked arrays of ribbons down to small inter-ribbon distances. Our work provides both intuitive insight into graphene plasmon interactions and a practical way of accurately describing complex graphene geometries based on the PWFs of the individual components.
Impact damage detection in composite panels using guided ultrasonic waves
NASA Astrophysics Data System (ADS)
Murat, Bibi Intan Suraya; Khalili, Pouyan; Fromme, Paul
2014-02-01
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.
Spectroscopic measurement of an atomic wave function
Kapale, Kishore T.; Qamar, Shahid; Zubairy, M. Suhail
2003-02-01
We present a simple spectroscopic method based on Autler-Townes spectroscopy to determine the center-of-mass atomic wave function. The detection of spontaneously emitted photons from a three-level atom, in which two upper levels are driven by a classical standing light, yields information about the position and momentum distribution of the atom [A. M. Herkommer, W. P. Schleich, and M. S. Zubairy, J. Mod. Opt. 44, 2507 (1997)]. In this paper, we show that both the amplitude and phase information of the center-of-mass atomic wave function can be obtained from these distributions after a series of conditional measurements on the atom and the emitted photon.
Spontaneous symmetry breaking in correlated wave functions
NASA Astrophysics Data System (ADS)
Kaneko, Ryui; Tocchio, Luca F.; Valentí, Roser; Becca, Federico; Gros, Claudius
2016-03-01
We show that Jastrow-Slater wave functions, in which a density-density Jastrow factor is applied onto an uncorrelated fermionic state, may possess long-range order even when all symmetries are preserved in the wave function. This fact is mainly related to the presence of a sufficiently strong Jastrow term (also including the case of full Gutzwiller projection, suitable for describing spin models). Selected examples are reported, including the spawning of Néel order and dimerization in spin systems, and the stabilization of charge and orbital order in itinerant electronic systems.
Semiclassical initial value treatment of wave functions
NASA Astrophysics Data System (ADS)
Kay, Kenneth G.
2010-05-01
A semiclassical initial value approximation for time-independent wave functions, previously derived for integrable systems, is rederived in a form which allows it to be applied to more general systems. The wave function is expressed as an integral over a Lagrangian manifold that is constructed by propagating trajectories from an initial manifold formed on a Poincaré surface. Even in the case of bound, integrable systems, it is unnecessary to identify action-angle variables or construct quantizing tori. The approximation is numerically tested for separable and highly chaotic two-dimensional quartic oscillator systems. For the separable (but highly anharmonic) system, the accuracy of the approximation is found to be excellent: overlaps of the semiclassical wave functions with the corresponding quantum wave functions exceed 0.999. For the chaotic system, semiclassical-quantum overlaps are found to range from 0.989 to 0.994, indicating accuracy that is still very good, despite the short classical trajectories used in the calculations.
Constructibility of the Universal Wave Function
NASA Astrophysics Data System (ADS)
Bolotin, Arkady
2016-05-01
This paper focuses on a constructive treatment of the mathematical formalism of quantum theory and a possible role of constructivist philosophy in resolving the foundational problems of quantum mechanics, particularly, the controversy over the meaning of the wave function of the universe. As it is demonstrated in the paper, unless the number of the universe's degrees of freedom is fundamentally upper bounded (owing to some unknown physical laws) or hypercomputation is physically realizable, the universal wave function is a non-constructive entity in the sense of constructive recursive mathematics. This means that even if such a function might exist, basic mathematical operations on it would be undefinable and subsequently the only content one would be able to deduce from this function would be pure symbolical.
Stream function solutions for steady water waves
NASA Astrophysics Data System (ADS)
Huang, Min-Chih; Hudspeth, Robert T.
Two stream function solutions for steady two-dimensional water waves are reviewed. The algorithm developed by DALRYMPLE (1974 , Proc. 6th Conf. Offshore Tech., pp. 843-856) and used by HUDSPETH and SLOTTA (1978 , Proceedings of the American Society of Civil Engineers, 104, 319-334) is compared with the algorithm developed by CHAPLIN (1980 , Coastal Engineering, 3, 179-205). By examining more closely the near-breaking wave conditions, it is shown that celerity does not increase monotonically with increasing dimensionless wave steepness. Numerical comparisons between the two algorithms indicate that the Dalrymple algorithm is more accurate for near-breaking waves and requires less computer programming effort. Neither algorithm appears to be able to predict breaking wave conditions as accurately as the COKELET (1977 , Philosophical Transactions of the Royal Society of London, A286, 183-230) algorithm. Numerical comparisons of the Dalrymple free surface error convergence criteria with the Chaplin significant figures convergence criteria indicate that the free surface error convergence criterion is more consistent for stream function representations.
Measurement of Oblique Impact-generated Shear Waves
NASA Technical Reports Server (NTRS)
Dahl, J. M.; Schultz, P. H.
2001-01-01
Experimental strain measurements reveal that oblique impacts can generate shear waves with displacements as large as those in the P-wave. Large oblique impacts may thus be more efficient sources of surface disruption than vertical impacts. Additional information is contained in the original extended abstract.
Covariance Constraints for Light Front Wave Functions
NASA Astrophysics Data System (ADS)
Müller, D.
2016-03-01
Light front wave functions (LFWFs) are often utilized to model parton distributions and form factors where their transverse and longitudinal momenta are tied to each other in some manner that is often guided by convenience. On the other hand, the cross talk of transverse and longitudinal momenta is governed by Poincaré symmetry and thus popular LFWF models are often not usable to model more intricate quantities such as generalized parton distributions. In this contribution a closer look to this issue is given and it is shown how to overcome the issue for two-body LFWFs.
Lanczos steps to improve variational wave functions
NASA Astrophysics Data System (ADS)
Becca, Federico; Hu, Wen-Jun; Iqbal, Yasir; Parola, Alberto; Poilblanc, Didier; Sorella, Sandro
2015-09-01
Gutzwiller-projected fermionic states can be efficiently implemented within quantum Monte Carlo calculations to define extremely accurate variational wave functions for Heisenberg models on frustrated two-dimensional lattices, not only for the ground state but also for low-energy excitations. The application of few Lanczos steps on top of these states further improves their accuracy, allowing calculations on large clusters. In addition, by computing both the energy and its variance, it is possible to obtain reliable estimations of exact results. Here, we report the cases of the frustrated Heisenberg models on square and Kagome lattices.
Impact detection using ultrasonic waves based on artificial immune system
NASA Astrophysics Data System (ADS)
Okamoto, Keisuke; Mita, Akira
2009-03-01
This paper presents a structural health monitoring system for judging structural condition of metallic plates by analyzing ultrasonic waves. Many critical accidents of structures like buildings and aircrafts are caused by small structural errors; cracks and loosened bolts etc. This is a reason why we need to detect little errors at an early stage. Moreover, to improve precision and to reduce cost for damage detection, it is necessary to build and update the database corresponding to environmental change. This study focuses our attention on the automatable structures, specifically, applying artificial immune system (AIS) algorithm to determine the structure safe or not. The AIS is a novelty computational detection algorithm inspired from biological defense system, which discriminates between self and non-self to reject nonself cells. Here, self is defined to be normal data patterns and non-self is abnormal data patterns. Furthermore, it is not only pattern recognition but also it has a storage function. In this study, a number of impact resistance experiments of duralumin plates, with normal structural condition and abnormal structural condition, are examined and ultrasonic waves are acquired by AE sensors on the surface of the aluminum plates. By accumulating several feature vectors of ultrasonic waves, a judging method, which can determine an abnormal wave as nonself, inspired from immune system is created. The results of the experiments show good performance of this method.
Multideterminant Wave Functions in Quantum Monte Carlo.
Morales, Miguel A; McMinis, Jeremy; Clark, Bryan K; Kim, Jeongnim; Scuseria, Gustavo E
2012-07-10
Quantum Monte Carlo (QMC) methods have received considerable attention over past decades due to their great promise for providing a direct solution to the many-body Schrodinger equation in electronic systems. Thanks to their low scaling with the number of particles, QMC methods present a compelling competitive alternative for the accurate study of large molecular systems and solid state calculations. In spite of such promise, the method has not permeated the quantum chemistry community broadly, mainly because of the fixed-node error, which can be large and whose control is difficult. In this Perspective, we present a systematic application of large scale multideterminant expansions in QMC and report on its impressive performance with first row dimers and the 55 molecules of the G1 test set. We demonstrate the potential of this strategy for systematically reducing the fixed-node error in the wave function and for achieving chemical accuracy in energy predictions. When compared to traditional quantum chemistry methods like MP2, CCSD(T), and various DFT approximations, the QMC results show a marked improvement over all of them. In fact, only the explicitly correlated CCSD(T) method with a large basis set produces more accurate results. Further developments in trial wave functions and algorithmic improvements appear promising for rendering QMC as the benchmark standard in large electronic systems. PMID:26588949
Proper Relativistic Wave Function via Canonical Transformations
NASA Astrophysics Data System (ADS)
Chen, Robert L. W.
2002-04-01
The canonical transformation of a classical field, e.g. that of the vibration of a continuous rod, has been largely unexplored. The difficulty is attributed to the following: Although the usual form of the Hamiltonium density of such a system has a momentum density, pie, is properly in the form of a density, the field, eta, is not. The potential energy depends on eta at different positions.(According to remarks in standard texts of analytical mechanics) It will now be shown that this problem can be solved.We worked out a new form of Hamiltonian density free of this difficulty and yet is equivalent to the usual form in that it yields the same wave equation. The method is then extended to the field of a real Klen-Gordon equation. It turned out that the canonical variables so obtained has all the required properties of a quantum wave function, i.e. having a non-negative conserved probability density etc. In addition, it is equivalent to the K-G equation and is therefore relativistic. In the meantime, it turns out that the usual method of canonical quantization really does not guarantee the final result to be relativitic even if we start out from a covariant form of Hamiltonan. It must be modified in accordance with the present method.
Analytical Wave Functions for Ultracold Collisions.
NASA Astrophysics Data System (ADS)
Cavagnero, M. J.
1998-05-01
Secular perturbation theory of long-range interactions(M. J. Cavagnero, PRA 50) 2841, (1994). has been generalized to yield accurate wave functions for near threshold processes, including low-energy scattering processes of interest at ultracold temperatures. In particular, solutions of Schrödinger's equation have been obtained for motion in the combined r-6, r-8, and r-10 potentials appropriate for describing an utlracold collision of two neutral ground state atoms. Scattering lengths and effective ranges appropriate to such potentials are readily calculated at distances comparable to the LeRoy radius, where exchange forces can be neglected, thereby eliminating the need to integrate Schrödinger's equation to large internuclear distances. Our method yields accurate base pair solutions well beyond the energy range of effective range theories, making possible the application of multichannel quantum defect theory [MQDT] and R-matrix methods to the study of ultracold collisions.
Intercellular Ca2+ Waves: Mechanisms and Function
Sanderson, Michael J.
2012-01-01
Intercellular calcium (Ca2+) waves (ICWs) represent the propagation of increases in intracellular Ca2+ through a syncytium of cells and appear to be a fundamental mechanism for coordinating multicellular responses. ICWs occur in a wide diversity of cells and have been extensively studied in vitro. More recent studies focus on ICWs in vivo. ICWs are triggered by a variety of stimuli and involve the release of Ca2+ from internal stores. The propagation of ICWs predominately involves cell communication with internal messengers moving via gap junctions or extracellular messengers mediating paracrine signaling. ICWs appear to be important in both normal physiology as well as pathophysiological processes in a variety of organs and tissues including brain, liver, retina, cochlea, and vascular tissue. We review here the mechanisms of initiation and propagation of ICWs, the key intra- and extracellular messengers (inositol 1,4,5-trisphosphate and ATP) mediating ICWs, and the proposed physiological functions of ICWs. PMID:22811430
String wave function across a Kasner singularity
Copeland, Edmund J.; Niz, Gustavo; Turok, Neil
2010-06-15
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.
Computer network defense through radial wave functions
NASA Astrophysics Data System (ADS)
Malloy, Ian J.
The purpose of this research is to synthesize basic and fundamental findings in quantum computing, as applied to the attack and defense of conventional computer networks. The concept focuses on uses of radio waves as a shield for, and attack against traditional computers. A logic bomb is analogous to a landmine in a computer network, and if one was to implement it as non-trivial mitigation, it will aid computer network defense. As has been seen in kinetic warfare, the use of landmines has been devastating to geopolitical regions in that they are severely difficult for a civilian to avoid triggering given the unknown position of a landmine. Thus, the importance of understanding a logic bomb is relevant and has corollaries to quantum mechanics as well. The research synthesizes quantum logic phase shifts in certain respects using the Dynamic Data Exchange protocol in software written for this work, as well as a C-NOT gate applied to a virtual quantum circuit environment by implementing a Quantum Fourier Transform. The research focus applies the principles of coherence and entanglement from quantum physics, the concept of expert systems in artificial intelligence, principles of prime number based cryptography with trapdoor functions, and modeling radio wave propagation against an event from unknown parameters. This comes as a program relying on the artificial intelligence concept of an expert system in conjunction with trigger events for a trapdoor function relying on infinite recursion, as well as system mechanics for elliptic curve cryptography along orbital angular momenta. Here trapdoor both denotes the form of cipher, as well as the implied relationship to logic bombs.
Nonlinear Trivelpiece-Gould waves: Frequency, functional form, and stability
NASA Astrophysics Data System (ADS)
Dubin, D. H. E.; Ashourvan, A.
2015-10-01
This paper considers the frequency, spatial form, and stability of nonlinear Trivelpiece-Gould (TG) waves on a cylindrical plasma column of length L and radius rp, treating both traveling waves and standing waves, and focussing on the regime of experimental interest in which L /rp≫1 . In this regime, TG waves are weakly dispersive, allowing strong mode-coupling between Fourier harmonics. The mode coupling implies that linear theory for such waves is a poor approximation even at fairly small amplitude, and nonlinear theories that include a small number of harmonics, such as three-wave parametric resonance theory, also fail to fully capture the stability properties of the system. It is found that nonlinear standing waves suffer jumps in their functional form as their amplitude is varied continuously. The jumps are caused by nonlinear resonances between the standing wave and nearly linear waves whose frequencies and wave numbers are harmonics of the standing wave. Also, the standing waves are found to be unstable to a multi-wave version of three-wave parametric resonance, with an amplitude required for instability onset that is much larger than expected from three wave theory. It is found that traveling waves are linearly stable for all amplitudes that could be studied, in contradiction to three-wave theory.
Nonlinear Trivelpiece-Gould Waves: Frequency, Functional Form, and Stability
NASA Astrophysics Data System (ADS)
Dubin, Daniel H. E.
2015-11-01
This poster considers the frequency, spatial form, and stability, of nonlinear Trivelpiece- Gould (TG) waves on a cylindrical plasma column of length L and radius rp, treating both traveling and standing waves, and focussing on the regime of experimental interest in which L/rp >> 1. In this regime TG waves are weakly dispersive, allowing strong mode-coupling between Fourier harmonics. The mode coupling implies that linear theory for such waves is a poor approximation even at fairly small amplitudes, and nonlinear theories that include only a small number of harmonics (such as 3-wave parametric resonance theory) fail to fully capture the stability properties of the system. We find that nonlinear standing waves suffer jumps in their functional form as their amplitude is varied continuously. The jumps are caused by nonlinear resonances between the standing wave and nearly linear waves whose frequencies and wave numbers are harmonics of the standing wave. Also, the standing waves are found to be unstable to a multi-wave version of 3-wave parametric resonance, with an amplitude required for instability onset that is much larger than expected from three wave theory. For traveling wave, linearly stability is found for all amplitudes that could be studied, in contradiction to 3-wave theory. Supported by National Science Foundation Grant PHY-1414570, Department of Energy Grants DE-SC0002451and DE-SC0008693.
POSSIBLE EXPERIMENTS ON WAVE FUNCTION LOCALIZATION DUE TO COMPTON SCATTERING
Aleksandrov, Alexander V; Danilov, Viatcheslav V; Gorlov, Timofey V; Liu, Yun; Shishlo, Andrei P; Nagaitsev,
2013-01-01
The reduction of a particle s wave function in the process of radiation or light scattering is a longstanding problem. Its solution will give a clue on processes that form, for example, wave functions of electrons constantly emitting synchrotron radiation quanta in storage rings. On a more global scale, it may shed light on wave function collapse due to the process of measurement. In this paper we consider various experimental options using Fermilab electron beams and a possible electron beam from the SNS linac and lasers to detect electron wave function change due to Compton scattering.
A Hammer-Impact, Aluminum, Shear-Wave Seismic Source
Haines, Seth S.
2007-01-01
Near-surface seismic surveys often employ hammer impacts to create seismic energy. Shear-wave surveys using horizontally polarized waves require horizontal hammer impacts against a rigid object (the source) that is coupled to the ground surface. I have designed, built, and tested a source made out of aluminum and equipped with spikes to improve coupling. The source is effective in a variety of settings, and it is relatively simple and inexpensive to build.
Impact induced solitary wave propagation through a woodpile structure
NASA Astrophysics Data System (ADS)
Kore, R.; Waychal, A.; Agarwal, S.; Yadav, P.; Uddin, Ahsan; Sahoo, N.; Shelke, A.
2016-02-01
In this paper, we investigate solitary wave propagation through a one-dimensional woodpile structure excited by low and high velocity impact. Woodpile structures are a sub-class of granular metamaterial, which supports propagation of nonlinear waves. Hertz contact law governs the behavior of the solitary wave propagation through the granular media. Towards an experimental study, a woodpile structure was fabricated by orthogonally stacking cylindrical rods. A shock tube facility has been developed to launch an impactor on the woodpile structure at a velocity of 30 m s-1. Embedded granular chain sensors were fabricated to study the behavior of the solitary wave. The impact induced stress wave is studied to investigate solitary wave parameters, i.e. contact force, contact time, and solitary wave velocity. With the aid of the experimental setup, numerical simulations, and a theoretical solution based on the long wavelength approximation, formation of the solitary wave in the woodpile structure is validated to a reasonable degree of accuracy. The nondispersive and compact supported solitary waves traveling at sonic wave velocity offer unique properties that could be leveraged for application in nondestructive testing and structural health monitoring.
Extreme waves impact on the ship mooring near berth
NASA Astrophysics Data System (ADS)
Leont'ev, Victor; Nudner, Igor; Semenov, Konstantin; Pelinovsky, Efim
2013-04-01
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.
NASA Astrophysics Data System (ADS)
O'Dea, A.; Haller, M. C.
2013-12-01
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.
Imaging the wave functions of adsorbed molecules
Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter
2014-01-01
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
Six Impossible Things: Fractional Charge From Laughlin's Wave Function
Shrivastava, Keshav N.
2010-12-23
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.
Light Front Wave Function for Hadrons with Arbitrary Twist
NASA Astrophysics Data System (ADS)
Vega, Alfredo; Schmidt, Ivan; Gutsche, Thomas; Lyubovitskij, Valery E.
2016-05-01
We present a phenomenological light-front wave function for hadrons with arbitrary twist dimension (mesons, baryons and multiquark states), which gives the correct scaling behavior of structure functions and form factors. Some examples of his uses are presented.
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...
Guided ultrasonic waves for impact damage detection in composite panels
NASA Astrophysics Data System (ADS)
Murat, B. I. S.; Khalili, P.; Fromme, P.
2014-03-01
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.
Effect of Forcing Function on Nonlinear Acoustic Standing Waves
NASA Technical Reports Server (NTRS)
Finkheiner, Joshua R.; Li, Xiao-Fan; Raman, Ganesh; Daniels, Chris; Steinetz, Bruce
2003-01-01
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.
Wave propagation in a plate after impact by a projectile
NASA Technical Reports Server (NTRS)
El-Raheb, M.; Wagner, P.
1987-01-01
The wave propagation in a circular plate after impact by a cylindrical projectile is studied. In the vicinity of impact, the pressure is computed numerically. An intense pressure pulse is generated that peaks 0.2 microns after impact, then drops sharply to a plateau. The response of the plate is determined adopting a modal solution of Mindlin's equations. Velocity and acceleration histories display both propagating and dispersive features.
Energy partitioning in ^{1}S-wave electron-impact ionization of atomic hydrogen
NASA Astrophysics Data System (ADS)
Shakeshaft, Robin
2010-03-01
Results of calculations of the integrated cross section and the energy distribution for ionization of ground-state hydrogen by S1-wave electron impact are presented. The breakup amplitude is expressed as a volume integral that contains an approximate final-state wave function which accounts for postcollision dynamic screening. The error in this wave function is accounted for by the response function, which is represented on a real discrete (Sturmian) basis, with its physical branch specified by the arrow of time. It is found that the energy distribution is primarily convex for impact energies from about 2 to 10 eV above threshold, and primarily flat from about 10 to 20 eV above threshold. The shape of the energy distribution appears to reflect both the competition between escape and recapture, and the substantial postcollision exchange of energy between the electrons. A rough, nonclassical criterion for predicting the curvature of the energy distribution is derived.
Waves in Periodic Dissipative Laminate Metamaterial Generated by Plate Impact
NASA Astrophysics Data System (ADS)
Franco Navarro, Pedro; Benson, David; Nesterenko, Vitali
2015-06-01
Waves generated by plate impact loading of Al/W laminates with different size of cell were investigated numerically depending on the impactor/cell mass ratio. The materials model took into account viscoplastic behavior of materials. It was observed that this mass ratio has a direct impact on the structure of stress pulses traveling through the composite. At the small impactor/cell mass ratio travelling waves closely resembling solitary waves were quickly formed near the impacted surface. They propagate as quasistationary weakly attenuating localized pulses. The properties of these pulses were satisfactory described based on a theoretical model using dispersive and nonlinear parameters of the materials similar to solitary solutions for the Korteweg-de Vries equation (KdV). The temperature at given pressure at the maximum is dramatically different then the temperature corresponding to the shock wave at the same pressure reflecting a different paths of loading. Increase of impactor/cell mass ratio results in the train of solitary like pulses which number increased with the increase of the impactor/cell mass ratio. At large impactor/cell mass ratio oscillatory stationary shock waves were formed. The leading front of these stationary shock waves was closely described by a solitary like pulse observed at small impactor/cell mass ratio. One of the authors (PFN) was supported by UCMexus Fellowship
Does the Schrödinger wave function describe a real physical wave?
NASA Astrophysics Data System (ADS)
Jung, Kurt
2011-07-01
In 1924 Louis de Broglie presented the phase wave model [1]. He postulated that particle and wave coexist. Both objects are coupled to each other by the phase harmony principle, which always tends to synchronize the oscillations of wave and particle. The escort wave model [2] replenishes the phase wave model by attributing a stochastic velocity component and a potential dependent rest mass to the particle. Moreover it introduces a novel method to deal with standing waves. In this new model a particle's trajectory is continuous but not deterministic because the particle is not only subjected to regular forces derived from external potentials but also to fluctuating forces. On this condition the space dependence of the wave escorting a particle agrees with the Schrödinger wave function. By a measurement process the phase harmony coupling is broken off. Contrary to the standard interpretation of quantum mechanics the escort wave does not collapse but disappears in the ocean of fluctuating waves, because it is no longer stabilized by the particle. The particle immediately starts to build up a new escort wave by adjusting its phase to the phases of fluctuating waves, whose frequencies and rest systems nearly agree with the corresponding magnitudes of the particle.
A miniaturized electromagnetic acoustic transducer for impact acoustic wave detection
NASA Astrophysics Data System (ADS)
Qin, Yexian; Xiang, Dan; Yang, Yubing; Li, Fang
2012-05-01
A miniaturized electromagnetic acoustic transducer (EMAT) is developed for impact acoustic wave detection. In this new sensor design, two neodymium iron boron (NdFeB) permanent magnets are used to provide high magnetic field and make the EMAT to be compact in size (13×5×5 mm3). The effect of a sensor's geometry on its frequency response was numerically analyzed for determining the size of EMAT during the sensor design. Miniaturized EMAT sensors were constructed and tested for detection of impact acoustic waves in aluminum plates of different thicknesses. To validate the experimental results of the EMAT sensor, the impact acoustic waves generated by a small dropping ball have been analytically calculated. Experimental results show good agreement with the analytical ones.
Heat waves in urban heat islands: interactions, impacts, and mitigation
NASA Astrophysics Data System (ADS)
Bou-Zeid, E.; Li, D.
2013-12-01
Urbanization rates and the intensity of anthropogenic global warming are both on the rise. By the middle of this century, climate change impacts on humans will be largely manifested in urban regions and will result from a combination of global to regional impacts related to greenhouse gas emissions, as well as regional to local impacts related to land-cover changes associated with urbanization. Alarmingly, our understanding of how these two distinct impacts will interact remains very poor. One example, which is the focus of this study, is the interaction of urban heat islands and heat waves. Urban heat islands (UHIs) are spatial anomalies consisting of higher temperatures over built terrain; while their intensity varies with many factors, it consistently increases with city size. UHIs will hence intensify in the future as cities expand. Heat waves are temporal anomalies in the regional temperatures that affect both urban and rural areas; there is high certainty that the frequency and intensity of such waves will increase as a result global warming. However, whether urban and rural temperatures respond in the same way to heat waves remains a critical unanswered question. In this study, a combination of observational and modeling analyses of a heat wave event over the Baltimore-Washington urban corridor reveals synergistic interactions between urban heat islands and heat waves. Not only do heat waves increase the regional temperatures, but they also intensify the difference between urban and rural temperatures. That is, their impact is stronger in cities and the urban heat stress during such waves is larger than the sum of the background urban heat island effect and the heat wave effect. We also develop a simple analytical model of this interaction that suggests that this exacerbated impact in urban areas is primarily to the lack of surface moisture, with low wind speeds also playing a smaller role. Finally, the effectiveness of cool and green roofs as UHI mitigation strategies during intense heat waves are evaluated at city scales. These strategies are shown to reduce urban surface temperatures in the Baltimore-Washington corridor by about 5 K and urban air temperatures by about 1 K. These reductions are most significant in the dense urban cores of the two cities, but they are not sufficient to fully offset the UHI effect.
Shock Waves Impacting Composite Material Plates: The Mutual Interaction
NASA Astrophysics Data System (ADS)
Andreopoulos, Yiannis
2013-02-01
High-performance, fiber-reinforced polymer composites have been extensively used in structural applications in the last 30 years because of their light weight combined with high specific stiffness and strength at a rather low cost. The automotive industry has adopted these materials in new designs of lightweight vehicles. The mechanical response and characterization of such materials under transient dynamic loading caused with shock impact induced by blast is not well understood. Air blast is associated with a fast traveling shock front with high pressure across followed by a decrease in pressure behind due to expansion waves. The time scales associated with the shock front are typically 103 faster than those involved in the expansion waves. Impingement of blast waves on structures can cause a reflection of the wave off the surface of the structure followed by a substantial transient aerodynamic load, which can cause significant deformation and damage of the structure. These can alter the overpressure, which is built behind the reflected shock. In addition, a complex aeroelastic interaction between the blast wave and the structure develops that can induce reverberation within an enclosure, which can cause substantial overpressure through multiple reflections of the wave. Numerical simulations of such interactions are quite challenging. They usually require coupled solvers for the flow and the structure. The present contribution provides a physics-based analysis of the phenomena involved, a critical review of existing computational techniques together with some recent results involving face-on impact of shock waves on thin composite plates.
Madden Julian Oscillation impacts on global ocean surface waves
NASA Astrophysics Data System (ADS)
Marshall, Andrew G.; Hendon, Harry H.; Durrant, Tom H.; Hemer, Mark A.
2015-12-01
We assess the impact of the tropical Madden Julian Oscillation (MJO) on global ocean wind waves using 30 years of wave data from a wave model hindcast that is forced with high resolution surface winds from the NCEP-CFSR reanalysis. We concentrate on the boreal winter season when the MJO has its greatest amplitude and is potentially a source of predictable wave impacts at intra-seasonal lead times. Statistically significant anomalies in significant wave height (Hs), peak wave period (Tp) and zonal wave energy flux (CgE) are found to covary with the intra-seasonal variation of surface zonal wind induced by the MJO as it traverses eastward from the western tropical Indian Ocean to the eastern tropical Pacific. Tp varies generally out of phase with Hs over the life cycle of the MJO, indicating that these MJO-wave anomalies are locally wind-generated rather than remotely generated by ocean swell. Pronounced Hs anomalies develop on the northwest shelf of Australia, where the MJO is known to influence sea level and surface temperatures, and in the western Caribbean Sea and Guatemalan-Panama Seas with enhanced wave anomalies apparent in the vicinity of the Tehuantepec and Papagayo gaps. Significant wave anomalies are also detected in the North Pacific and North Atlantic oceans in connection with the MJO teleconnection to the extratropics via atmospheric wave propagation. The impact in the north Atlantic stems from induction of the high phase of the North Atlantic Oscillation (NAO) about 1 week after MJO convection traverses the Indian Ocean, and the low phase of the NAO about one week after suppressed convection traverses the Indian Ocean. Strong positive Hs anomalies maximize on the Northern European coast in the positive NAO phase and vice versa for the negative NAO phase. The MJO also influences the occurrence of daily low (below the 5th percentile) and high (above the 95th percentile) wave conditions across the tropics and in the North Pacific and North Atlantic, emphasizing that the MJO may be a valuable source of intra-seasonal predictability of surface wave variability.
Boundary conditions on internal three-body wave functions
Mitchell, Kevin A.; Littlejohn, Robert G.
1999-10-01
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.
Impact of Functionally Graded Cylinders: Theory
NASA Technical Reports Server (NTRS)
Aboudi, Jacob; Pindera, Marek-Jerzy; Arnold, S. M. (Technical Monitor)
2001-01-01
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.
Extracting momentum distributions from time-dependent wave functions
NASA Astrophysics Data System (ADS)
Macek, J. H.; Ovchinnikov, S. Y.; Sternberg, J. B.
2010-03-01
Time dependent state vectors for atomic processes are computed numerically and amplitudes for transitions to bound states obtained by projecting time-dependent state vectors onto bound state vectors at large times. Similar projections onto plane waves are used for continuum states. This requires large times since only then do plane waves represent particle motion. To use finite times, one projects onto asymptotic state vectors. Since the asymptotic states are often not known other procedures are sought. One such procedure replaces coordinates by the their classical counterpart, namely vt, where v is the velocity, and uses that coordinate space wave functions go over to momentum space wave functions at large times. This gives momentum distributions directly. In essence, if an exact wave function is obtained then there is no need to project that wave function onto imperfectly known asymptotic states to extract electron momentum distributions. We show how more familiar projection procedures derive from this simple prescription, which we call ``The Imaging Theorem" since it shows that momentum distributions image time-dependent wave functions.
The effects of extracorporeal shock wave lithotripsy on pacemaker function.
Langberg, J; Abber, J; Thuroff, J W; Griffin, J C
1987-09-01
Twenty-two pacemaker pulse generators were exposed to shock waves of an extracorporeal shock wave lithotripter to assess the effects of the extremely high pressure transients on pacemaker function. The pulse generator and distal aspect of the lead were positioned 5 cm from the focal point of the lithotripter and 10 cm from each other. Pulse generator function was analyzed during shock wave delivery synchronized with pulse generator output, during shock waves at a rate faster than the escape rate, and after exposure to lithotripsy. During shock waves delivered synchronously with pulse generator output, only one of 22 pulse generators malfunctioned by intermittently reverting to the magnet rate. When subjected to shock waves at a rate greater than the escape rate, 50% of the pulse generators were inhibited by electromechanical interference from the lithotripter. Both bipolar and unipolar devices were affected. However, analysis after exposure to shock waves showed that none of the pacemakers was damaged or spuriously reprogrammed. In conclusion, cardiac pacemakers do not appear to be damaged or reprogrammed by exposure to extracorporeal shock wave lithotripsy. The likelihood of false inhibition appears to be very low if shock waves are delivered synchronously with the QRS. PMID:2444938
Impact of plunging breaking waves on a partially submerged cube
NASA Astrophysics Data System (ADS)
Wang, A.; Ikeda, C.; Duncan, J. H.
2013-11-01
The impact of a deep-water plunging breaking wave on a partially submerged cube is studied experimentally in a tank that is 14.8 m long and 1.2 m wide with a water depth of 0.91 m. The breakers are created from dispersively focused wave packets generated by a programmable wave maker. The water surface profile in the vertical center plane of the cube is measured using a cinematic laser-induced fluorescence technique with movie frame rates ranging from 300 to 4,500 Hz. The pressure distribution on the front face of the cube is measured with 24 fast-response sensors simultaneously with the wave profile measurements. The cube is positioned vertically at three heights relative to the mean water level and horizontally at a distance from the wave maker where a strong vertical water jet is formed. The portion of the water surface between the contact point on the front face of the cube and the wave crest is fitted with a circular arc and the radius and vertical position of the fitted circle is tracked during the impact. The vertical acceleration of the contact point reaches more than 50 times the acceleration of gravity and the pressure distribution just below the free surface shows a localized high-pressure region with a very high vertical pressure gradient. This work is supported by the Office of Naval Research under grant N000141110095.
Multi-time wave functions for quantum field theory
Petrat, Sören; Tumulka, Roderich
2014-06-15
Multi-time wave functions such as ϕ(t{sub 1},x{sub 1},…,t{sub N},x{sub N}) have one time variable t{sub j} for each particle. This type of wave function arises as a relativistic generalization of the wave function ψ(t,x{sub 1},…,x{sub N}) of non-relativistic quantum mechanics. We show here how a quantum field theory can be formulated in terms of multi-time wave functions. We mainly consider a particular quantum field theory that features particle creation and annihilation. Starting from the particle–position representation of state vectors in Fock space, we introduce multi-time wave functions with a variable number of time variables, set up multi-time evolution equations, and show that they are consistent. Moreover, we discuss the relation of the multi-time wave function to two other representations, the Tomonaga–Schwinger representation and the Heisenberg picture in terms of operator-valued fields on space–time. In a certain sense and under natural assumptions, we find that all three representations are equivalent; yet, we point out that the multi-time formulation has several technical and conceptual advantages. -- Highlights: •Multi-time wave functions are manifestly Lorentz-covariant objects. •We develop consistent multi-time equations with interaction for quantum field theory. •We discuss in detail a particular model with particle creation and annihilation. •We show how multi-time wave functions are related to the Tomonaga–Schwinger approach. •We show that they have a simple representation in terms of operator valued fields.
The Pion Renormalized Light-Cone Wave Function
NASA Astrophysics Data System (ADS)
Trawiński, Arkadiusz P.
2016-03-01
An approximate light-cone wave function for the pion effective quark-antiquark Fock sector corresponding to a small value of the renormalization group parameter is presented. The approximate wave function is motivated by the LF-holography and the quadratic confinement potential in the front form of Hamiltonian dynamics, which is in harmony with the linear confining potential in the instant form. The pion radius, decay constant and form-factor are also presented.
Structure of the number-projected BCS wave function
NASA Astrophysics Data System (ADS)
Dukelsky, J.; Pittel, S.; Esebbag, C.
2016-03-01
We study the structure of the number-projected BCS (PBCS) wave function in the particle-hole basis, displaying its similarities with coupled clusters theory (CCT). The analysis of PBCS together with several modifications suggested by the CCT wave function is carried out for the exactly solvable Richardson model involving a pure pairing Hamiltonian acting in a space of equally spaced, doubly degenerate levels. We point out the limitations of PBCS to describe the nonsuperconducting regime and suggest possible avenues for improvement.
Multi-time wave functions for quantum field theory
NASA Astrophysics Data System (ADS)
Petrat, Sren; Tumulka, Roderich
2014-06-01
Multi-time wave functions such as ?(t1,x,,tN,x) have one time variable tj for each particle. This type of wave function arises as a relativistic generalization of the wave function ?(t,x,,x) of non-relativistic quantum mechanics. We show here how a quantum field theory can be formulated in terms of multi-time wave functions. We mainly consider a particular quantum field theory that features particle creation and annihilation. Starting from the particle-position representation of state vectors in Fock space, we introduce multi-time wave functions with a variable number of time variables, set up multi-time evolution equations, and show that they are consistent. Moreover, we discuss the relation of the multi-time wave function to two other representations, the Tomonaga-Schwinger representation and the Heisenberg picture in terms of operator-valued fields on space-time. In a certain sense and under natural assumptions, we find that all three representations are equivalent; yet, we point out that the multi-time formulation has several technical and conceptual advantages.
Factorized molecular wave functions: Analysis of the nuclear factor
Lefebvre, R.
2015-06-07
The exact factorization of molecular wave functions leads to nuclear factors which should be nodeless functions. We reconsider the case of vibrational perturbations in a diatomic species, a situation usually treated by combining Born-Oppenheimer products. It was shown [R. Lefebvre, J. Chem. Phys. 142, 074106 (2015)] that it is possible to derive, from the solutions of coupled equations, the form of the factorized function. By increasing artificially the interstate coupling in the usual approach, the adiabatic regime can be reached, whereby the wave function can be reduced to a single product. The nuclear factor of this product is determined by the lowest of the two potentials obtained by diagonalization of the potential matrix. By comparison with the nuclear wave function of the factorized scheme, it is shown that by a simple rectification, an agreement is obtained between the modified nodeless function and that of the adiabatic scheme.
Breaking wave impact forces on truss support structures for offshore wind turbines
NASA Astrophysics Data System (ADS)
Cieślikiewicz, Witold; Gudmestad, Ove T.; Podrażka, Olga
2014-05-01
Due to depletion of the conventional energy sources, wind energy is becoming more popular these days. Wind energy is being produced mostly from onshore farms, but there is a clear tendency to transfer wind farms to the sea. The foundations of offshore wind turbines may be truss structures and might be located in shallow water, where are subjected to highly varying hydrodynamic loads, particularly from plunging breaking waves. There are models for impact forces prediction on monopiles. Typically the total wave force on slender pile from breaking waves is a superposition of slowly varying quasi-static force, calculated from the Morison equation and additional dynamical, short duration force due to the impact of the breaker front or breaker tongue. There is not much research done on the truss structures of wind turbines and there are still uncertainties on slamming wave forces, due to plunging breaking waves on those structures. Within the WaveSlam (Wave slamming forces on truss structures in shallow water) project the large scale tests were carried out in 2013 at the Large Wave Flume in Forschungszentrum Küste (FZK) in Hannover, Germany. The following institutions participated in this initiative: the University of Stavanger and the Norwegian University of Science and Technology (project management), University of Gdańsk, Poland, Hamburg University of Technology and the University of Rostock, Germany and Reinertsen AS, Norway. This work was supported by the EU 7th Framework Programme through the grant to the budget of the Integrating Activity HYDRALAB IV. The main aim of the experiment was to investigate the wave slamming forces on truss structures, development of new and improvement of existing methods to calculate forces from the plunging breakers. The majority of the measurements were carried out for regular waves with specified frequencies and wave heights as well as for the irregular waves based on JONSWAP spectrum. The truss structure was equipped with both total and local force transducers which measured the response of the structure to the impact force. Also, the free surface elevations, the water particle velocity and the water particle acceleration were recorded during the WaveSlam experiment. Both the total and the local force data have been analysed using the Frequency Response Function method, which has been already applied to the estimation of the wave slamming forces. The results of this classical approach were compared to the calculated slamming forces based on Goda and Wienke and Oumeraci theories. Slamming wave forces and slamming coefficients calculated using both models appeared to be very much larger than those obtained from the analysed recorded data, therefore there is a need for further research. Details of this research and modelling results will be presented in the final poster.
Donor wave functions in Si gauged by STM images
NASA Astrophysics Data System (ADS)
Saraiva, A. L.; Salfi, J.; Bocquel, J.; Voisin, B.; Rogge, S.; Capaz, Rodrigo B.; Calderón, M. J.; Koiller, Belita
2016-01-01
The triumph of effective mass theory in describing the energy spectrum of dopants does not guarantee that the model wave functions will withstand an experimental test. Such wave functions have recently been probed by scanning tunneling spectroscopy, revealing localized patterns of resonantly enhanced tunneling currents. We show that the shape of the conducting splotches resembles a cut through Kohn-Luttinger (KL) hydrogenic envelopes, which modulate the interfering Bloch states of conduction electrons. All the nonmonotonic features of the current profile are consistent with the charge density fluctuations observed between successive {001 } atomic planes, including a counterintuitive reduction of the symmetry—a heritage of the lowered point group symmetry at these planes. A model-independent analysis of the diffraction figure constrains the value of the electron wave vector to k0=(0.82 ±0.03 ) (2 π /aSi) . Unlike prior measurements, averaged over a sizable density of electrons, this estimate is obtained directly from isolated electrons. We further investigate the model-specific anisotropy of the wave function envelope, related to the effective mass anisotropy. This anisotropy appears in the KL variational wave function envelope as the ratio between Bohr radii b /a . We demonstrate that the central-cell-corrected estimates for this ratio are encouragingly accurate, leading to the conclusion that the KL theory is a valid model not only for energies but for wave functions as well.
Parametric dependence of ocean wave-radar modulation transfer functions
NASA Technical Reports Server (NTRS)
Plant, W. J.; Keller, W. C.; Cross, A.
1983-01-01
Microwave techniques at X and L band were used to determine the dependence of ocean-wave radar modulation transfer functions (MTFs) on various environmental and radar parameters during the Marine Remote Sensing experiment of 1979 (MARSEN 79). These MIF are presented, as are coherence functions between the AM and FM parts of the backscattered microwave signal. It is shown that they both depend on several of these parameters. Besides confirming many of the properties of transfer functions reported by previous authors, indications are found that MTFs decrease with increasing angle between wave propagation and antenna-look directions but are essentially independent of small changes in air-sea temperature difference. However, coherence functions are much smaller when the antennas are pointed perpendicular to long waves. It is found that X band transfer functions measured with horizontally polarized microwave radiation have larger magnitudes than those obtained by using vertical polarization.
Rossby wave Green's functions in an azimuthal wind
NASA Astrophysics Data System (ADS)
Webb, G. M.; Duba, C. T.; Hu, Q.
2016-05-01
Green's functions for Rossby waves in an azimuthal wind are obtained, in which the stream-function $\\psi$ depends on $r$, $\\phi$ and $t$, where $r$ is cylindrical radius and $\\phi$ is the azimuthal angle in the $\\beta$-plane relative to the easterly direction, in which the $x$-axis points east and the $y$-axis points north. The Rossby wave Green's function with no wind is obtained using Fourier transform methods, and is related to the previously known Green's function obtained for this case, which has a different but equivalent form to the Green's function obtained in the present paper. We emphasize the role of the wave eikonal solution, which plays an important role in the form of the solution. The corresponding Green's function for a rotating wind with azimuthal wind velocity ${\\bf u}=\\Omega r{\\bf e}_\\phi$ ($\\Omega=$const.) is also obtained by Fourier methods, in which the advective rotation operator in position space is transformed to a rotation operator in ${\\bf k}$ transform space. The finite Rossby deformation radius is included in the analysis. The physical characteristics of the Green's functions are delineated and applications are discussed. In the limit as $\\Omega\\to 0$, the rotating wind Green's function reduces to the Rossby wave Green function with no wind.
Impact Localization Using Lamb Wave and Spiral FSAT
NASA Astrophysics Data System (ADS)
Rimal, Nischal
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.
Do Heat Waves have an Impact on Terrestrial Water Storage?
NASA Astrophysics Data System (ADS)
Brena-Naranjo, A.; Teuling, R.; Pedrozo-Acuña, A.
2014-12-01
Recent works have investigated the impact of heat waves on the surface energy and carbon balance. However, less attention has been given to the impacts on terrestrial hydrology. During the summer of 2010, the occurrence of an exceptional heat wave affected severely the Northern Hemisphere. The extension (more than 2 million km2) and severity of this extreme event caused substantial ecosystem damage (more than 1 million ha of forest fires), economic and human losses (~500 billion USD and more than 17 million of indirect deaths, respectively). This work investigates for the first time the impacts of the 2010 summer heat wave on terrestrial water storage. Our study area comprises three different regions where air temperature records were established or almost established during the summer: Western Russia, the Middle East and Eastern Sahel. Anomalies of terrestrial water storage derived from the Gravity Recovery and Climate Experiment (GRACE) were used to infer water storage deficits during the 2003-2013 period. Our analysis shows that Russia experienced the most severe water storage decline, followed by the Middle East, whereas Eastern Sahel was not significantly affected. The impact of the heat wave was spatially uniform in Russia but highly variable in the Middle East, with the Northern part substantially more affected than the Southern region. Lag times between maxima air temperatures and lower water storage deficits for Russia and the Middle East were approximately two and seven months, respectively. The results suggest that the response of terrestrial water storage to heat waves is stronger in energy-limited environments than in water-limited regions. Such differences in the magnitude and timing between meteorological and hydrological extremes can be explained by the propagation time between atmospheric water demand and natural or anthropogenic sources of water storage.
New approach to folding with the Coulomb wave function
Blokhintsev, L. D.; Savin, D. A.; Kadyrov, A. S.; Mukhamedzhanov, A. M.
2015-05-15
Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.
Delta function excitation of waves in the earth's ionosphere
NASA Technical Reports Server (NTRS)
Vidmar, R. J.; Crawford, F. W.; Harker, K. J.
1983-01-01
Excitation of the earth's ionosphere by delta function current sheets is considered, and the temporal and spatial evolution of wave packets is analyzed for a two-component collisional F2 layer. Approximations of an inverse Fourier-Laplace transform via saddle point methods provide plots of typical wave packets. These illustrate cold plasma wave theory and may be used as a diagnostic tool since it is possible to relate specific features, e.g., the frequency of a modulation envelope, to plasma parameters such as the electron cyclotron frequency. It is also possible to deduce the propagation path length and orientation of a remote radio beacon.
Diving-wave migration using Airy functions
Albertin, U.K.
1993-08-10
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.
NASA Astrophysics Data System (ADS)
Sternberg, James; Macek, J. H.; Ovchinnikov, Serge; Lee, Teck-Ghee; Schultz, D. R.
2008-05-01
Vortices are a nearly ubiquitous feature of nature. It is well known that they form in large scale processes such as weather, but they are also formed in the quantum realm. One place where they can be seen quite clearly is in the wave functions for ion- atom collisions at a set impact parameter. In this work we use a very low noise and highly accurate numerical method to propagate the time dependent Schr"odinger equation (TDSE) for such a collision. With this method we see the formation of vortices in the wave function, the interaction between them and their destruction. We also observe how the transport of angular momentum by vortices affects the overall behavior of the wave function.
Test of the Pluvinage wave function for the helium ground state
NASA Astrophysics Data System (ADS)
Jones, S.; Macek, Joseph H.; Madison, D. H.
2004-07-01
The accuracy of the Pluvinage wave function for the ground state of helium is investigated by considering a number of different physical processes including double ionization by photoabsorption, Compton scattering, and electron impact. In the high-energy limit of these processes, the accuracy of the initial ground state can be ascertained without reference to the final double-continuum state. In this limit, we find that a Hylleraas description is superior to the Pluvinage one. For intermediate energies, final-state correlation becomes important, so we employ a 3C description of the final state (the 3C wave function is the double-continuum analog of the Pluvinage wave function). In this case, however, better agreement with experiment is obtained with the Pluvinage initial state. A possible explanation for this seemingly paradoxical result is suggested.
Canonical Transformation of a Classical Wave to Generate a Complex Wave Function
NASA Astrophysics Data System (ADS)
Chen, Robert L. W.
2001-04-01
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.
Charmed Quark Component of the Photon Wave Function
Anisovich, V.V.; Dakhno, L.G.; Markov, V.N.; Nikonov, V.A.; Sarantsev, A.V.
2005-12-01
We determine the cc-bar component of the photon wave function on the basis of (i) the data on the transitions e{sup +}e{sup -} {yields} J/{psi}(3096), {psi}(3686), {psi}(4040), {psi}(4415), (ii) partial widths of the two-photon decays {eta}{sub c0}(2979), {chi}{sub c0}(3415), {chi}{sub c2}(3556) {yields} {gamma}{gamma}, and (iii) wave functions of the charmonium states obtained by solving the Bethe-Salpeter equation for the cc-bar system. Using the obtained cc-bar component of the photon wave function, we calculate the {gamma}{gamma}-decay partial widths for radial excitation of the 2S state, {eta}{sub c0}(3594) {yields} {gamma}{gamma}, and 2P states {chi}{sub c0}(3849), {chi}{sub c2}(3950) {yields} {gamma}{gamma}.
Generalized pairing wave functions in electronic structure quantum Monte Carlo
NASA Astrophysics Data System (ADS)
Bajdich, Michal; Mitas, Lubos; Schmidt, Kevin E.
2007-03-01
We investigate several types of trial wave functions with pairing orbitals in fixed-node quantum Monte Carlo. Following upon our previous study[1], we explore the possibilities of expanding the wave function in linear combinations of pfaffians. We observe that molecular systems require much larger expansions than atomic systems and linear combinations of a few pfaffians lead to rather small gains in correlation energy. Further, we test the wave function based on fully-antisymmetrized product of independent pair orbitals. Despite its seemingly large variational potential, we do not observe significant gains in correlation energy. Finally, we combine these developments with the recently proposed inhomogeneous backflow transformations[2]. The trade-offs between computational efficiency and amounts correlation energy recovered will be discussed. [1] M. Bajdich et al. Phys. Rev. Lett. 96, 130201 (2006). [2] N. D. Drummond et. al., J. Chem. Phys. 124, 224104 (2006).
B meson wave function in k{sub T} factorization
Li Hsiangnan; Liao, Huei-Shih
2004-10-01
We study the asymptotic behavior of the B meson wave function in the framework of k{sub T} factorization theorem. We first construct a definition of the k{sub T}-dependent B meson wave function, which is free of light-cone divergences. Next-to-leading-order corrections are then calculated based on this definition. The treatment of different types of logarithms in the above corrections, including the Sudakov logarithms, and those depending on a renormalization scale and on an infrared regulator, is summarized. The criticism raised in the literature on our resummation formalism and Sudakov effect is responded. We show that the B meson wave function remains normalizable after taking into account renormalization-group evolution effects, contrary to the observation derived in the collinear factorization theorem.
Pain's Impact on Adaptive Functioning
ERIC Educational Resources Information Center
Breau, L. M.; Camfield, C. S.; McGrath, P. J.; Finley, G. A.
2007-01-01
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…
Wave propagation of functionally graded material plates in thermal environments.
Sun, Dan; Luo, Song-Nan
2011-12-01
The wave propagation of an infinite functionally graded plate in thermal environments is studied using the higher-order shear deformation plate theory. The thermal effects and temperature-dependent material properties are both taken into account. The temperature field considered is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. Considering the effects of transverse shear deformation and rotary inertia, the governing equations of the wave propagation in the functionally graded plate are derived by using the Hamilton's principle. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. Numerical examples show that the characteristics of wave propagation in the functionally graded plate are relates to the volume fraction index and thermal environment of the functionally graded plate. The influences of the volume fraction distributions and temperature on wave propagation of functionally graded plate are discussed in detail. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring. PMID:21663930
Evolution of wave function in a dissipative system
NASA Technical Reports Server (NTRS)
Yu, Li-Hua; Sun, Chang-Pu
1994-01-01
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.
Concerning Infeasibility of the Wave Functions of the Universe
NASA Astrophysics Data System (ADS)
Bolotin, Arkady
2015-09-01
Difficulties with finding the general exact solutions to the Wheeler-DeWitt equation, i.e. the wave functions of the Universe, are known and well documented. However, the present paper draws attention to a completely different matter, which is rarely if ever discussed in relation to this equation, namely, the time complexity of the Wheeler-DeWitt equation, that is, the time required to exactly solve the equation for a given universe. As it is shown in the paper, whatever generic exact algorithm is used to solve the equation, most likely such an algorithm cannot be faster than brute force, which makes the wave functions of the Universe infeasible.
Impact of sea-level rise and coral mortality on the wave dynamics and wave forces on barrier reefs.
Baldock, T E; Golshani, A; Callaghan, D P; Saunders, M I; Mumby, P J
2014-06-15
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
Simulations of Wave Propagation in the Jovian Atmosphere after SL9 Impact Events
NASA Astrophysics Data System (ADS)
Pond, Jarrad W.; Palotai, C.; Korycansky, D.; Harrington, J.
2013-10-01
Our previous numerical investigations into Jovian impacts, including the Shoemaker Levy- 9 (SL9) event (Korycansky et al. 2006 ApJ 646. 642; Palotai et al. 2011 ApJ 731. 3), the 2009 bolide (Pond et al. 2012 ApJ 745. 113), and the ephemeral flashes caused by smaller impactors in 2010 and 2012 (Hueso et al. 2013; Submitted to A&A), have covered only up to approximately 3 to 30 seconds after impact. Here, we present further SL9 impacts extending to minutes after collision with Jupiter’s atmosphere, with a focus on the propagation of shock waves generated as a result of the impact events. Using a similar yet more efficient remapping method than previously presented (Pond et al. 2012; DPS 2012), we move our simulation results onto a larger computational grid, conserving quantities with minimal error. The Jovian atmosphere is extended as needed to accommodate the evolution of the features of the impact event. We restart the simulation, allowing the impact event to continue to progress to greater spatial extents and for longer times, but at lower resolutions. This remap-restart process can be implemented multiple times to achieve the spatial and temporal scales needed to investigate the observable effects of waves generated by the deposition of energy and momentum into the Jovian atmosphere by an SL9-like impactor. As before, we use the three-dimensional, parallel hydrodynamics code ZEUS-MP 2 (Hayes et al. 2006 ApJ.SS. 165. 188) to conduct our simulations. Wave characteristics are tracked throughout these simulations. Of particular interest are the wave speeds and wave positions in the atmosphere as a function of time. These properties are compared to the characteristics of the HST rings to see if shock wave behavior within one hour of impact is consistent with waves observed at one hour post-impact and beyond (Hammel et al. 1995 Science 267. 1288). This research was supported by National Science Foundation Grant AST-1109729 and NASA Planetary Atmospheres Program Grant NNX11AD87G.
Hydrodynamic waves and correlation functions in dusty plasmas
Wang, X.; Bhattacharjee, A.
1997-11-01
A hydrodynamic description of strongly coupled dusty plasmas is given when physical quantities vary slowly in space and time and the system can be assumed to be in local thermodynamic equilibrium. The linear waves in such a system are analyzed. In particular, a dispersion equation is derived for low-frequency dust acoustic waves, including collisional damping effects, and compared with experimental results. The linear response of the system is calculated from the fluctuation-dissipation theorem and the hydrodynamic equations. The requirement that these two calculations coincide constrains the particle correlation function for slowly varying perturbations. It is shown that in the presence of weakly damped, long-wavelength dust-acoustic waves, the dust autocorrelation function is of the Debye{endash}H{umlt u}ckel form and the characteristic shielding distance is the dust Debye length. {copyright} {ital 1997 American Institute of Physics.}
Calculation of the nucleon structure function from the nucleon wave function
NASA Technical Reports Server (NTRS)
Hussar, Paul E.
1993-01-01
Harmonic oscillator wave functions have played an historically important role in our understanding of the structure of the nucleon, most notably by providing insight into the mass spectra of the low-lying states. High energy scattering experiments are known to give us a picture of the nucleon wave function at high-momentum transfer and in a frame in which the nucleon is traveling fast. A simple model that crosses the twin bridges of momentum scale and Lorentz frame that separate the pictures of the nucleon wave function provided by the deep inelastic scattering data and by the oscillator model is presented.
Numerical computation of an Evans function for travelling waves.
Harley, K; van Heijster, P; Marangell, R; Pettet, G J; Wechselberger, M
2015-08-01
We demonstrate a geometrically inspired technique for computing Evans functions for the linearised operators about travelling waves. Using the examples of the F-KPP equation and a Keller-Segel model of bacterial chemotaxis, we produce an Evans function which is computable through several orders of magnitude in the spectral parameter and show how such a function can naturally be extended into the continuous spectrum. In both examples, we use this function to numerically verify the absence of eigenvalues in a large region of the right half of the spectral plane. We also include a new proof of spectral stability in the appropriate weighted space of travelling waves of speed c≥2√δ in the F-KPP equation. PMID:26048189
Explicitly correlated wave function for a boron atom
NASA Astrophysics Data System (ADS)
Puchalski, Mariusz; Komasa, Jacek; Pachucki, Krzysztof
2015-12-01
We present results of high-precision calculations for a boron atom's properties using wave functions expanded in the explicitly correlated Gaussian basis. We demonstrate that the well-optimized 8192 basis functions enable a determination of energy levels, ionization potential, and fine and hyperfine splittings in atomic transitions with nearly parts per million precision. The results open a window to a spectroscopic determination of nuclear properties of boron including the charge radius of the proton halo in the 8B nucleus.
Simulation of wind wave growth with reference source functions
NASA Astrophysics Data System (ADS)
Badulin, Sergei I.; Zakharov, Vladimir E.; Pushkarev, Andrei N.
2013-04-01
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 = Cdissμ4w?N (k)θ(? - ?diss) (3) Here frequency-dependent wave steepness μ2w = 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 μw 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.
Impact of Tsunami-Generated Gravity Waves on the Ionosphere
NASA Astrophysics Data System (ADS)
Huba, J. D.; Drob, D. P.
2014-12-01
The NRL first-principles ionosphere model SAMI3 is used to study the ionospheric effects associated with tsunami-driven gravity waves. It is shown that gravity-wave induced variations in the neutral wind lead to plasma velocity variations both perpendicular and parallel to the geomagnetic field. Moreover, the electric field induced by the neutral wind perturbations can map to the conjugate hemisphere. Thus, electron density variations can be generated in both hemispheres which impact the total electron content (TEC) and 6300A airglow emission. It is found that the TEC exhibits variations +/- 0.15 TECU and the 6300A airglow emission variation is up to +/- 2.5% relative to the unperturbed background airglow. These results are consistent with observational data. Research supported by NRL Base Funds and ONR BRC program.
Impact of boat-generated waves on intertidal estuarine sediments
NASA Astrophysics Data System (ADS)
Blanpain, O.; Deloffre, J.; Lafite, R.; Gomit, G.; Calluaud, D.; David, L.
2010-12-01
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.
How close can we get waves to wave functions, including potential?
NASA Astrophysics Data System (ADS)
Faletič, Sergej
2016-05-01
In the following article we show that mechanical waves on a braced string can have the same shapes as important wave functions in introductory quantum mechanics. A braced string is a string with additional transversal springs that serve as external "potential". The aim is not to suggest teaching quantum mechanics with these analogies. Instead, the aim is to provide students with some additional relevant experience in wave mechanics before they are introduced to quantum mechanics. We show how this experience can be used in a constructivist sense as the basis for building quantum concepts. We consider energy transfer along such string and show that penetration of a wave into a region with high "potential" is not unexpected. We also consider energy transfer between two such strings and show that it can appear point-like even though the wave is an extended object. We also suggest that applying quantization of energy transfer to wave phenomena can explain some of the more difficult to accept features of quantum mechanics.
Local properties of three-body atomic wave functions
Krivec, R.; Mandelzweig, V. B.; Varga, K.
2000-06-01
The local properties and accuracy of the positronium negative-ion (Ps{sup -}) ground-state wave functions obtained by the stochastic variational method (SVM) and by direct solution of the Schroedinger equation with the help of the correlation-function hyperspherical-harmonic method (CFHHM) are studied and compared. Though the energy, calculated by both methods, agrees to up to ten digits, the amplitudes of the values of the operator D=H{psi}/E{psi}-1, characterizing local deviation of the wave function from its true value, in all of the coordinate space in the SVM are consistently larger (by up to five orders of magnitude) than in the CFHHM, despite the fact that the SVM observables except <{delta}(r{sub k})> converge to significantly more digits than the CFHHM observables for their respective selected bases. (c) 2000 The American Physical Society.
Edge states for the Kalmeyer-Laughlin wave function
NASA Astrophysics Data System (ADS)
Herwerth, Benedikt; Sierra, Germán; Tu, Hong-Hao; Cirac, J. Ignacio; Nielsen, Anne E. B.
2015-12-01
We study lattice wave functions obtained from the SU(2)1 Wess-Zumino-Witten conformal field theory. Following Moore and Read's construction, the Kalmeyer-Laughlin fractional quantum Hall state is defined as a correlation function of primary fields. By an additional insertion of Kac-Moody currents, we associate a wave function with each state of the conformal field theory. These wave functions span the complete Hilbert space of the lattice system. On the cylinder, we study global properties of the lattice states analytically and correlation functions numerically using a Metropolis Monte Carlo method. By comparing short-range bulk correlations, numerical evidence is provided that the states with one current operator represent edge states in the thermodynamic limit. We show that the edge states with one Kac-Moody current of lowest order have a good overlap with low-energy excited states of a local Hamiltonian, for which the Kalmeyer-Laughlin state approximates the ground state. For some states, exact parent Hamiltonians are derived on the cylinder. These Hamiltonians are SU(2) invariant and nonlocal with up to four-body interactions.
Wave impact loads: The role of the flip-through
NASA Astrophysics Data System (ADS)
Lugni, C.; Brocchini, M.; Faltinsen, O. M.
2006-12-01
The impact of waves upon a vertical, rigid wall during sloshing is analyzed with specific focus on the modes that lead to the generation of a flip-through [M. J. Cooker and D. H. Peregrine, "A model for breaking wave impact pressures," in Proceedings of the 22nd International Conference on Coastal Engineering (ASCE, Delft, 1990), Vol. 2, pp. 1473-1486]. Experimental data, based on a time-resolved particle image velocimetry technique and on a novel free-surface tracking method [M. Miozzi, "Particle image velocimetry using feature tracking and Delaunay tessellation," in Proceedings of the 12th International Symposium on Applications of Laser Techniques to Fluid Mechanics (2004)], are used to characterize the details of the flip-through dynamics while wave loads are computed by integrating the experimental pressure distributions. Three different flip-through modes are observed and studied in dependence on the amount and modes of air trapping. No air entrapment characterizes a "mode (a) flip-through," engulfment of a single, well-formed air bubble is typical of a "mode (b)" event, while the generation of a fine-scale air-water mixing occurs for a "mode (c)" event. Upward accelerations of the flip-through jet exceeding 1500g have been measured and the generation/collapse process of a small air cavity is described in conjunction with the available pressure time histories. Predictions of the vertical pressure distributions made with the pressure-impulse model of Cooker and Peregrine [M. J. Cooker and D. H. Peregrine, "Pressure-impulse theory for liquid impact problems," J. Fluid Mech. 297, 193 (1995)] show good agreement with the experimental data.
Phases of Augmented Hadronic Light-Front Wave Functions
Brodsky, Stanley J.; Pasquini, Barbara; Xiao, Bo-Wen; Yuan, Feng; /LBNL, NSD /RIKEN BNL
2010-02-15
It is an important question whether the final/initial state gluonic interactions which lead to naive-time-reversal-odd single-spin asymmetries and diffraction at leading twist can be associated in a definite way with the light-front wave function hadronic eigensolutions of QCD. We use light-front time-ordered perturbation theory to obtain augmented light-front wave functions which contain an imaginary phase which depends on the choice of advanced or retarded boundary condition for the gauge potential in light-cone gauge. We apply this formalism to the wave functions of the valence Fock states of nucleons and pions, and show how this illuminates the factorization properties of naive-time-reversal-odd transverse momentum dependent observables which arise from rescattering. In particular, one calculates the identical leading-twist Sivers function from the overlap of augmented light-front wavefunctions that one obtains from explicit calculations of the single-spin asymmetry in semi-inclusive deep inelastic lepton-polarized nucleon scattering where the required phases come from the final-state rescattering of the struck quark with the nucleon spectators.
Deducing spectroscopic factors from wave-function asymptotics
Capel, P.; Danielewicz, P.; Nunes, F. M.
2010-11-15
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 {sup 11}Be. 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.
Helicon Wave Physics Impacts on Electrodeless Thruster Design
NASA Technical Reports Server (NTRS)
Gilland, James
2003-01-01
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.
Helicon Wave Physics Impacts on Electrodeless Thruster Design
NASA Technical Reports Server (NTRS)
Gilland, James H.
2007-01-01
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.
Impact of rheumatoid arthritis on sexual function
Tristano, Antonio G
2014-01-01
Sexuality is a complex aspect of the human being’s life and is more than just the sexual act. Normal sexual functioning consists of sexual activity with transition through the phases from arousal to relaxation with no problems, and with a feeling of pleasure, fulfillment and satisfaction. Rheumatic diseases may affect all aspects of life including sexual functioning. The reasons for disturbing sexual functioning are multifactorial and comprise disease-related factors as well as therapy. Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by progressive joint destruction resulting from chronic synovial inflammation. It leads to various degrees of disability, and ultimately has a profound impact on the social, economic, psychological, and sexual aspects of the patient’s life. This is a systemic review about the impact of RA on sexual functioning. PMID:24829873
Wave function analysis of MHC-peptide interactions.
Crdenas, Constanza; Obregn, Mateo; Balbn, Alejandro; Villaveces, Jos Luis; Patarroyo, Manuel E
2007-01-01
We have carried out an analysis of the wave function data for three MHC-peptide complexes: HLA-DRbeta1*0101-HA, HLA-DRbeta1*0401-HA and HLA-DRbeta1*0401-Col. We used quantum chemistry computer programs to generate wave function coefficients for these complexes, from which we obtained both molecular and atomic orbital data for both pocket and peptide amino acids within each pocket region. From these discriminated data, interaction molecular orbitals (IMOs) were identified as those with large and similar atomic orbital coefficient contributions from both pocket and peptide amino acids. The present results correlate well with our previous research where only electrostatic moments were used to explore molecular component interactions. Furthermore, we show a quantum chemical methodology to produce more fine-grained results concerning amino acid behavior in the MHC-peptide interaction. PMID:16793298
Configuration interaction wave functions: A seniority number approach
Alcoba, Diego R.; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E.; Oña, Ofelia B.
2014-06-21
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.
Reconstructing the Shock Wave From the Wolfe Creek Meteorite Impact.
NASA Astrophysics Data System (ADS)
Heine, C.; O'Neill, C. J.
2003-12-01
The Wolfe Creek meteorite crater is an 800m diameter impact structure located in the Tanami Desert near Hall's Creek, Western Australia. The crater formed <300000 years ago, and is the 2nd largest crater from which fragments of the impacting meteorite (a medium octahedrite) have been recovered. We present the results of new ground based geophysical (magnetics and gravity) surveys conducted over the structure in July-August, 2003. The results highlight the simple structure of the crater under the infilling sediments, and track the extent of deformation and the ejecta blanket under the encroaching sanddunes. The variations in the dip of the foliations around the crater rim confirm that the crater approached from East-Northeast, as deduced from the ejecta distribution, and provide constraints on the kinetic energy and angle of the impactor. We also use the distribution of shocked quartz in the target rock (Devonian sandstones) to reconstruct the shock loading conditions of the impact using the Grieve and Robertson (1976) criterion. We also use a Simplified Arbitrary Langrangian-Eulerian hydrocode (SALE 2) to simulate the propagation of shock waves through a material described by a Tillotson equation of state. Using the deformational and PT constraints of the Wolfe-Creek crater, we can estimate the partitioning of kinetic energy as a result of this medium-size impact.
Multifractal electronic wave functions in the Anderson model of localization
Schreiber, M.; Grussbach, H. )
1992-06-20
In this paper, investigations of the multifractal properties of electronic wave functions in disordered samples are reviewed. The characteristic mass exponents of the multifractal measure, the generalized dimensions and the singularity spectra are discussed for typical cases. New results for large 3D systems are reported, suggesting that the multifractal properties at the mobility edge which separates localized and extended states are independent of the microscopic details of the model.
Fine structure and analytical quantum-defect wave functions
NASA Astrophysics Data System (ADS)
Kostelecký, V. Alan; Nieto, Michael Martin; Truax, D. Rodney
1988-11-01
We investigate the domain of validity of previously proposed analytical wave functions for atomic quantum-defect theory. This is done by considering the fine-structure splitting of alkali-metal and singly ionized alkaline-earth atoms. The Landé formula is found to be naturally incorporated. A supersymmetric-type integer is necessary for finite results. Calculated splittings correctly reproduce the principal features of experimental values for alkali-like atoms.
Reconstruction of Bohm trajectories and wave functions from interferometric measurements
NASA Astrophysics Data System (ADS)
Schleich, W. P.; Freyberger, M.; Zubairy, M. S.
2013-01-01
We propose a generalization of the technique of quantum state reconstruction to obtain the space derivative of the phase of a wave function, which is central to the hydrodynamic formulation of quantum mechanics in the manner of Madelung and Bohm. In this way we can construct Bohm trajectories and make contact with a recent experiment [Kocsis , Science10.1126/science.1202218 332, 1170 (2011)] extracting these trajectories after a double slit.
Sensory Function: Insights From Wave 2 of the National Social Life, Health, and Aging Project
Kern, David W.; Wroblewski, Kristen E.; Chen, Rachel C.; Schumm, L. Philip; McClintock, Martha K.
2014-01-01
Objectives. Sensory function, a critical component of quality of life, generally declines with age and influences health, physical activity, and social function. Sensory measures collected in Wave 2 of the National Social Life, Health, and Aging Project (NSHAP) survey focused on the personal impact of sensory function in the home environment and included: subjective assessment of vision, hearing, and touch, information on relevant home conditions and social sequelae as well as an improved objective assessment of odor detection. Method. Summary data were generated for each sensory category, stratified by age (62–90 years of age) and gender, with a focus on function in the home setting and the social consequences of sensory decrements in each modality. Results. Among both men and women, older age was associated with self-reported impairment of vision, hearing, and pleasantness of light touch. Compared with women, men reported significantly worse hearing and found light touch less appealing. There were no gender differences for vision. Overall, hearing loss seemed to have a greater impact on social function than did visual impairment. Discussion. Sensory function declines across age groups, with notable gender differences for hearing and light touch. Further analysis of sensory measures from NSHAP Wave 2 may provide important information on how sensory declines are related to health, social function, quality of life, morbidity, and mortality in this nationally representative sample of older adults. PMID:25360015
Impact! Chandra Images a Young Supernova Blast Wave
NASA Astrophysics Data System (ADS)
2000-05-01
Two images made by NASA's Chandra X-ray Observatory, one in October 1999, the other in January 2000, show for the first time the full impact of the actual blast wave from Supernova 1987A (SN1987A). The observations are the first time that X-rays from a shock wave have been imaged at such an early stage of a supernova explosion. Recent observations of SN 1987A with the Hubble Space Telescope revealed gradually brightening hot spots from a ring of matter ejected by the star thousands of years before it exploded. Chandra's X-ray images show the cause for this brightening ring. A shock wave is smashing into portions of the ring at a speed of 10 million miles per hour (4,500 kilometers per second). The gas behind the shock wave has a temperature of about ten million degrees Celsius, and is visible only with an X-ray telescope. "With Hubble we heard the whistle from the oncoming train," said David Burrows of Pennsylvania State University, University Park, the leader of the team of scientists involved in analyzing the Chandra data on SN 1987A. "Now, with Chandra, we can see the train." The X-ray observations appear to confirm the general outlines of a model developed by team member Richard McCray of the University of Colorado, Boulder, and others, which holds that a shock wave has been moving out ahead of the debris expelled by the explosion. As this shock wave collides with material outside the ring, it heats it to millions of degrees. "We are witnessing the birth of a supernova remnant for the first time," McCray said. The Chandra images clearly show the previously unseen, shock-heated matter just inside the optical ring. Comparison with observations made with Chandra in October and January, and with Hubble in February 2000, show that the X-ray emission peaks close to the newly discovered optical hot spots, and indicate that the wave is beginning to hit the ring. In the next few years, the shock wave will light up still more material in the ring, and an inward moving, or reverse, shock wave will heat the material ejected in the explosion itself. "The supernova is digging up its own past," said McCray. The observations were made on October 6, 1999, using the Advanced CCD Imaging Spectrometer (ACIS) and the High Energy Transmission Grating, and again on January 17, 2000, using ACIS. Other members of the team were Eli Michael of the University of Colorado; Dr. Una Hwang, Dr. Steven Holt and Dr. Rob Petre of NASA's Goddard Space Flight Center in Greenbelt, MD; Professor Roger Chevalier of the University of Virginia, Charlottesville; and Professors Gordon Garmire and John Nousek of Pennsylvania State University. The results will be published in an upcoming issue of the Astrophysical Journal. The ACIS instrument was built for NASA by the Massachusetts Institute of Technology, Cambridge, and Pennsylvania State University. The High Energy Transmission Grating was built by the Massachusetts Institute of Technology. NASA's Marshall Space Flight Center in Huntsville, AL, manages the Chandra program. TRW, Inc., Redondo Beach, CA, is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, MA. More About SN 1987A Images to illustrate this release and more information on Chandra's progress can be found on the Internet at: http://chandra.harvard.edu/photo/2000/sn1987a/index.html AND http://chandra.nasa.gov More About SN 1987A
Joint inversion of receiver function and surface wave dispersion observations
NASA Astrophysics Data System (ADS)
Julià, J.; Ammon, C. J.; Herrmann, R. B.; Correig, A. M.
2000-10-01
We implement a method to invert jointly teleseismic P-wave receiver functions and surface wave group and phase velocities for a mutually consistent estimate of earth structure. Receiver functions are primarily sensitive to shear wave velocity contrasts and vertical traveltimes, and surface wave dispersion measurements are sensitive to vertical shear wave velocity averages. Their combination may bridge resolution gaps associated with each individual data set. We formulate a linearized shear velocity inversion that is solved using a damped least-squares scheme that incorporates a priori smoothness constraints for velocities in adjacent layers. The data sets are equalized for the number of data points and physical units in the inversion process. The combination of information produces a relatively simple model with a minimal number of sharp velocity contrasts. We illustrate the approach using noise-free and realistic noise simulations and conclude with an inversion of observations from the Saudi Arabian Shield. Inversion results for station SODA, located in the Arabian Shield, include a crust with a sharp gradient near the surface (shear velocity changing from 1.8 to 3.5kms-1 in 3km) underlain by a 5-km-thick layer with a shear velocity of 3.5kms-1 and a 27-km-thick layer with a shear velocity of 3.8kms-1, and an upper mantle with an average shear velocity of 4.7kms-1. The crust-mantle transition has a significant gradient, with velocity values varying from 3.8 to 4.7kms-1 between 35 and 40km depth. Our results are compatible with independent inversions for crustal structure using refraction data.
NASA Astrophysics Data System (ADS)
Hedayatrasa, Saeid; Bui, Tinh Quoc; Zhang, Chuanzeng; Lim, Chee Wah
2014-02-01
Numerical modeling of the Lamb wave propagation in functionally graded materials (FGMs) by a two-dimensional time-domain spectral finite element method (SpFEM) is presented. The high-order Chebyshev polynomials as approximation functions are used in the present formulation, which provides the capability to take into account the through thickness variation of the material properties. The efficiency and accuracy of the present model with one and two layers of 5th order spectral elements in modeling wave propagation in FGM plates are analyzed. Different excitation frequencies in a wide range of 28-350 kHz are investigated, and the dispersion properties obtained by the present model are verified by reference results. The through thickness wave structure of two principal Lamb modes are extracted and analyzed by the symmetry and relative amplitude of the vertical and horizontal oscillations. The differences with respect to Lamb modes generated in homogeneous plates are explained. Zero-crossing and wavelet signal processing-spectrum decomposition procedures are implemented to obtain phase and group velocities and their dispersion properties. So it is attested how this approach can be practically employed for simulation, calibration and optimization of Lamb wave based nondestructive evaluation techniques for the FGMs. The capability of modeling stress wave propagation through the thickness of an FGM specimen subjected to impact load is also investigated, which shows that the present method is highly accurate as compared with other existing reference data.
S-wave velocity structure in southwest China from surface wave tomography and receiver functions
NASA Astrophysics Data System (ADS)
Wang, W.; Wu, J.; Fang, L.; Lai, G.; Yang, T.
2013-12-01
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.
New Offshore Approach to Reduce Impact of Tsunami Waves
NASA Astrophysics Data System (ADS)
Anant Chatorikar, Kaustubh
2016-04-01
The world is facing an increasing frequency and intensity of natural disaster that has devastating impacts on society. As per International Strategy for Disaster Reduction (ISDR), it has been observed that over five million people were killed or affected in last 10 years and huge amount of economic losses occurred due to natural disaster. The 2011 tsunami in Japan showed a tremendous setback to existing technology of tsunami protection. More than 25,000 lives have been lost, Apart from that the damage to the nuclear power stations has severely affected the nearby populace and marine life. After the 2004 tsunami, world's effort has been concentrated on early warning and effective mitigation plans to defend against tsunami. It is anybody's guess as to what would have happened if such natural calamity specifically tsunami of such magnitude strikes our nation as country has already suffered from it in 2004 and seen its disastrous effects. But the point is what if such calamity strikes the mega cities like Chennai, Mumbai and Kolkata again where there is extensive human habitation and conventional warning systems and mitigation methods are not effective when it comes to huge population of these cities, destruction caused by it will be worse than nuclear weapon strike as there is also very high possibility of deaths due to stampede. This paper talks about an idea inspired from daily routine and its relation with fundamental physics as well as method of its deployment is discussed. According to this idea when wave will strike the coast, aim is not to stop it but to reduce its impact within the permissible impact limits of existing infrastructure by converting it into foam wave with help of surfactants, thereby saving human lives as well as complications of Mitigation.
Statistical properties and correlation functions for drift waves
NASA Technical Reports Server (NTRS)
Horton, W.
1986-01-01
The dissipative one-field drift wave equation is solved using the pseudospectral method to generate steady-state fluctuations. The fluctuations are analyzed in terms of space-time correlation functions and modal probability distributions. Nearly Gaussian statistics and exponential decay of the two-time correlation functions occur in the presence of electron dissipation, while in the absence of electron dissipation long-lived vortical structures occur. Formulas from renormalized, Markovianized statistical turbulence theory are given in a local approximation to interpret the dissipative turbulence.
Transverse instability of a plane front of fast impact ionization waves
Kyuregyan, A. S.
2012-05-15
The transverse instability of a plane front of fast impact ionization waves in p{sup +}-n-n{sup +} semiconductor structures with a finite concentration of donors N in the n layer has been theoretically analyzed. It is assumed that the high velocity u of impact ionization waves is ensured owing to the avalanche multiplication of the uniform background of electrons and holes whose concentration {sigma}{sub b} ahead of the front is high enough for the continuum approximation to be applicable. The problem of the calculation of the growth rate s of a small harmonic perturbation with wavenumber k is reduced to the eigenvalue problem for a specific homogeneous Volterra equation of the second kind containing the sum of double and triple integrals of an unknown eigenfunction. This problem has been solved by the method of successive approximations. It has been shown that the function s(k) for small k values increases monotonically in agreement with the analytical theory reported in Thermal Engineering 58 (13), 1119 (2011), reaches a maximum s{sub M} at k = k{sub M}, then decreases, and becomes negative at k > k{sub 01}. This behavior of the function s(k) for short-wavelength perturbations is due to a decrease in the distortion of the field owing to a finite thickness of the space charge region of the front and 'smearing' of perturbation of concentrations owing to the transverse transport of charge carriers. The similarity laws for perturbations with k Greater-Than-Or-Equivalent-To k{sub M} have been established: at fixed {sigma}{sub b} values and the maximum field strength on the front E{sub 0M}, the growth rate s depends only on the ratio k/N and the boundary wavenumber k{sub 01} {proportional_to} N. The parameters s{sub M}, k{sub M}, and k{sub 01}, which determine the perturbation growth dynamics and the upper boundary of the instability region for impact ionization waves, have been presented as functions of E{sub 0M}. These dependences indicate that the model of a plane impact ionization wave is insufficient for describing the operation of avalanche voltage sharpers and that fronts of fast streamers in the continuum approximation should be stable with respect to transverse perturbations in agreement with the previously reported numerical simulation results. The results have been confirmed by the numerical simulation of the evolution of small harmonic perturbations of the steady-state plane impact ionization wave.
S wave velocity structure in southwest China from surface wave tomography and receiver functions
NASA Astrophysics Data System (ADS)
Wang, Weilai; Wu, Jianping; Fang, Lihua; Lai, Guijuan; Yang, Ting; Cai, Yan
2014-02-01
Using the surface wave records of 504 teleseismic events at 50 temporary and 92 permanent seismic stations in southwest China, we obtain phase velocity maps at 10, 15, 25, 40, 60, and 75 s at a grid spacing of 0.5° × 0.5° from the interstation correlation method and surface wave tomography. We also obtain the S wave velocity structures beneath three profiles using the joint inversion of receiver functions and surface waves. At short periods (10 and 15 s), high-velocity zones (HVZs) are found in the Panzhihua-Emeishan region, the Sichuan basin and the Weixi-Lijiang region surrounding the low-velocity zones (LVZs) from Songpan-Ganzi block to the east of Lijiang, where the elevations are significantly higher. At long periods (40, 60, and 75 s), HVZs are found in the Weixi-Lijiang region, the Panzhihua-Chuxiong basin,and the Kunming-Tonghai region, which form a belt in the center part of the study area. The fast polarization directions on both sides of the belt defined by the shear wave splitting of teleseismic SKS waves vary significantly and indicate that the flow of material from the plateau is blocked in two different depth intervals and leads to different horizontal extents. The long-period maps and the structures along the three profiles show that LVZs are present in the upper mantle beneath rapidly slipping fault zones, such as the Anninghe-Zemuhe-Xiaojiang fault zone, the Red River fault zone, and the Xiaojinhe fault zone, implying that these faults penetrate deep into the mantle.
Computational aspects of the continuum quaternionic wave functions for hydrogen
Morais, J.
2014-10-15
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 R{sup 3} and R{sup 4}). 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.
NASA Astrophysics Data System (ADS)
Werby, M. F.; Strayer, M. R.; Nagarajan, M. A.
1980-06-01
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.
Influence of rotating electron wave functions on l -shell ionization and alignment
NASA Astrophysics Data System (ADS)
Legrand, I. C.; Dörner, R.; Schmidt-Böcking, H.; Zoran, V.
In adiabatic ion-atom collisions, the target electron distribution will follow the rotation of the internuclear axis resulting in a change of the subshell ionization probabilities as well as of the alignment tensor as compared with the case of frozen electron wave functions. In the present work we compare SCA calculations based on frozen and rotating relativistic electron wave functions with experimental l-subshell probabilities and l 3-subshell differential alignment measured by Dörner et al. for 1 MeV protons on Samarium. In this case, where the intrashell couplings play a minor role, the agreement between calculations and experiment is significantly improved assuming a partial rotation of the target electron distribution during the collision, possibly depending on substate and impact parameter.
Wave function of Vasiliev's universe: A few slices thereof
NASA Astrophysics Data System (ADS)
Anninos, Dionysios; Denef, Frederik; Harlow, Daniel
2013-10-01
We study the partition function of the free Sp(N) conformal field theory (CFT) recently conjectured to be dual to asymptotically de Sitter higher-spin gravity in four dimensions. We compute the partition function of this CFT on a round sphere as a function of a finite mass deformation, on a squashed sphere as a function of the squashing parameter, and on an S2×S1 geometry as a function of the relative size of S2 and S1. We find that the partition function is divergent at large negative mass in the first case, and for small S1 in the third case. It is globally peaked at zero squashing in the second case. Through the duality this partition function contains information about the wave function of the universe. We show that the divergence at small S1 occurs also in Einstein gravity if certain complex solutions are included, but the divergence in the mass parameter is new. We suggest an interpretation for this divergence as indicating an instability of de Sitter space in higher-spin gravity, consistent with general arguments that de Sitter space cannot be stable in quantum gravity.
A Critical Examination of Wind-Wave Spectral Functional Form
NASA Technical Reports Server (NTRS)
Huang, Norden E.; Long, Steven R.
1999-01-01
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.
Li, Yong; Fang, Hui; Min, Changjun; Yuan, Xiaocong
2015-01-01
Under the usual approximation of treating a biological particle as a spheroidal droplet, we consider the analysis of its size and shape with the high frequency photoacoustics and develop a numerical method which can simulate its characteristic photoacoustic waves. This numerical method is based on the calculation of spheroidal wave functions, and when comparing to the finite element model (FEM) calculation, can reveal more physical information and can provide results independently at each spatial points. As the demonstration, red blood cells (RBCs) and MCF7 cell nuclei are studied, and their photoacoustic responses including field distribution, spectral amplitude, and pulse forming are calculated. We expect that integrating this numerical method with the high frequency photoacoustic measurement will form a new modality being extra to the light scattering method, for fast assessing the morphology of a biological particle. PMID:26442830
NASA Astrophysics Data System (ADS)
Li, Yong; Fang, Hui; Min, Changjun; Yuan, Xiaocong
2015-10-01
Under the usual approximation of treating a biological particle as a spheroidal droplet, we consider the analysis of its size and shape with the high frequency photoacoustics and develop a numerical method which can simulate its characteristic photoacoustic waves. This numerical method is based on the calculation of spheroidal wave functions, and when comparing to the finite element model (FEM) calculation, can reveal more physical information and can provide results independently at each spatial points. As the demonstration, red blood cells (RBCs) and MCF7 cell nuclei are studied, and their photoacoustic responses including field distribution, spectral amplitude, and pulse forming are calculated. We expect that integrating this numerical method with the high frequency photoacoustic measurement will form a new modality being extra to the light scattering method, for fast assessing the morphology of a biological particle.
Chameleon fields, wave function collapse and quantum gravity
NASA Astrophysics Data System (ADS)
Zanzi, A.
2015-07-01
Chameleon fields are quantum (usually scalar) fields, with a density-dependent mass. In a high-density environment, the mass of the chameleon is large. On the contrary, in a small-density environment (e.g. on cosmological distances), the chameleon is very light. A model where the collapse of the wave function is induced by chameleon fields is presented. During this analysis, a Chameleonic Equivalence Principle (CEP) will be formulated: in this model, quantum gravitation is equivalent to a conformal anomaly. Further research efforts are necessary to verify whether this proposal is compatible with phenomeno logical constraints.
Wave-function monopoles in Bose-Einstein condensates
NASA Astrophysics Data System (ADS)
Busch, Th.; Anglin, J. R.
1999-10-01
Experimental preparation of multispecies Bose-Einstein condensates should permit the creation of topologically stable defects beyond the superfluid vortex. But the coldness and isolation of condensates should also permit the survival for observable durations of ``pseudodefects,'' such as the one-dimensional dark soliton: localized structures related to a defect but not topologically stable. In this paper we investigate the viability of pseudodefects beyond one dimension, by examining ``wave-function monopoles'' in two-species condensates in two dimensions. We identify interesting instabilities, including a ``dancing mode'' for monopoles of higher winding number, and (in a one-dimensional limit) ``superfluid roulette.''
Is spontaneous wave function collapse testable at all?
NASA Astrophysics Data System (ADS)
Diósi, Lajos
2015-07-01
Mainstream literature on spontaneous wave function collapse never reflects on or profits from the formal coincidence and conceptual relationship with standard collapse under time-continuous quantum measurement (monitoring). I propose some easy lessons of standard monitoring theory which would make spontaneous collapse models revise some of their claims. In particular, the objective detection of spontaneous collapse remains impossible as long as the correct identification of what corresponds to the signal in standard monitoring is missing from spontaneous collapse models, the physical detectability of the “signal” is not stated explicitly and, finally, the principles of physical detection are not revealed.
A critical survey of wave propagation and impact in composite materials
NASA Technical Reports Server (NTRS)
Moon, F. C.
1973-01-01
A review of the field of stress waves in composite materials is presented covering the period up to December 1972. The major properties of waves in composites are discussed and a summary is made of the major experimental results in this field. Various theoretical models for analysis of wave propagation in laminated, fiber and particle reinforced composites are surveyed. The anisotropic, dispersive and dissipative properties of stress pulses and shock waves in such materials are reviewed. A review of the behavior of composites under impact loading is presented along with the application of wave propagation concepts to the determination of impact stresses in composite plates.
NASA Astrophysics Data System (ADS)
Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael
2015-01-01
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.
The impact of the summer 2003 heat wave in Iberia: how should we measure it?
Díaz, J; García-Herrera, R; Trigo, R M; Linares, C; Valente, M A; De Miguel, J M; Hernández, E
2006-01-01
We present a new approach to improve the reliability of quantifying the impact of a heat wave on mortality rates. We show, for the recent European summer 2003 heat wave, that the use of absolute maximum temperature values, or number of days above a given threshold, can be misleading. Here, we have assessed the impact of the heat wave on Iberian mortality by applying a four step procedure: (1) calculating, for each observatory, the local maximum temperature (T (max)) distributions, (2) calculating the corresponding 95th percentile values (T (threshold)), (3) locally defining extremely hot days (EHD) as those days on which the local threshold of the 95th percentile of the series is exceeded, and (4) calculating the total degrees-days (DD) of exceedance, by calculating the difference T (max)-T (threshold) and summing these values for all days above T (threshold). We show that the relationship between summer mortality rates and the DD index is non-linear and can be described by a logarithmic function, with a correlation coefficient of 0.78, which explains 60.6% of the mortality variance (F value of 24.64, significant at P<0.0001). Using maximum temperatures, no significant relationship is found with mortality, whereas the EHD frequency shows a significant association with mortality, albeit weaker than that obtained with DD. PMID:16235090
Gauge-fixed Wannier wave functions for fractional topological insulators
NASA Astrophysics Data System (ADS)
Wu, Yang-Le; Regnault, N.; Bernevig, B. Andrei
2012-08-01
We propose an improved scheme to construct many-body trial wave functions for fractional Chern insulators (FCI), using one-dimensional localized Wannier basis. The procedure borrows from the original scheme on a continuum cylinder, but is adapted to finite-size lattice systems with periodic boundaries. It fixes several issues of the continuum description that made the overlap with the exact ground states insignificant. The constructed lattice states are translationally invariant, and have the correct degeneracy as well as the correct relative and total momenta. Our prescription preserves the (possible) inversion symmetry of the lattice model, and is isotropic in the limit of flat Berry curvature. By relaxing the maximally localized hybrid Wannier orbital prescription, we can form an orthonormal basis of states which, upon gauge fixing, can be used in lieu of the Landau orbitals. We find that the exact ground states of several known FCI models at ν=1/3 filling are well captured by the lattice states constructed from the Laughlin wave function. The overlap is higher than 0.99 in some models when the Hilbert space dimension is as large as 3×104 in each total momentum sector.
Wave functions for fractional Chern insulators in disk geometry
NASA Astrophysics Data System (ADS)
He, Ai-Lei; Luo, Wei-Wei; Wang, Yi-Fei; Gong, Chang-De
2015-12-01
Recently, fractional Chern insulators (FCIs), also called fractional quantum anomalous Hall (FQAH) states, have been theoretically established in lattice systems with topological flat bands. These systems exhibit similar fractionalization phenomena to the conventional fractional quantum Hall (FQH) systems. Using the mapping relationship between the FQH states and the FCI/FQAH states, we construct the many-body wave functions of the fermionic FCI/FQAH states in disk geometry with the aid of the generalized Pauli principle (GPP) and Jack polynomials. Compared with the ground state by the exact diagonalization method, the wave-function overlap is higher than 0.97, even when the Hilbert space dimension is as large as 3 × 106. We also use the GPP and the Jack polynomials to construct edge excitations for the fermionic FCI/FQAH states. The quasi-degeneracy sequences of fermionic FCI/FQAH systems reproduce the prediction of the chiral Luttinger liquid theory, complementing the exact diagonalization results with larger lattice sizes and more particles.
Horizon wave-function and the quantum cosmic censorship
NASA Astrophysics Data System (ADS)
Casadio, Roberto; Micu, Octavian; Stojkovic, Dejan
2015-07-01
We investigate the Cosmic Censorship Conjecture by means of the horizon wave-function (HWF) formalism. We consider a charged massive particle whose quantum mechanical state is represented by a spherically symmetric Gaussian wave-function, and restrict our attention to the superextremal case (with charge-to-mass ratio α > 1), which is the prototype of a naked singularity in the classical theory. We find that one can still obtain a normalisable HWF for α2 < 2, and this configuration has a non-vanishing probability of being a black hole, thus extending the classically allowed region for a charged black hole. However, the HWF is not normalisable for α2 > 2, and the uncertainty in the location of the horizon blows up at α2 = 2, signalling that such an object is no more well-defined. This perhaps implies that a quantum Cosmic Censorship might be conjectured by stating that no black holes with charge-to-mass ratio greater than a critical value (of the order of √{ 2}) can exist.
Theory of steady-state plane tunneling-assisted impact ionization waves
Kyuregyan, A. S.
2013-07-15
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.
Climate change impact on wave energy in the Persian Gulf
NASA Astrophysics Data System (ADS)
Kamranzad, Bahareh; Etemad-Shahidi, Amir; Chegini, Vahid; Yeganeh-Bakhtiary, Abbas
2015-06-01
Excessive usage of fossil fuels and high emission of greenhouse gases have increased the earth's temperature, and consequently have changed the patterns of natural phenomena such as wind speed, wave height, etc. Renewable energy resources are ideal alternatives to reduce the negative effects of increasing greenhouse gases emission and climate change. However, these energy sources are also sensitive to changing climate. In this study, the effect of climate change on wave energy in the Persian Gulf is investigated. For this purpose, future wind data obtained from CGCM3.1 model were downscaled using a hybrid approach and modification factors were computed based on local wind data (ECMWF) and applied to control and future CGCM3.1 wind data. Downscaled wind data was used to generate the wave characteristics in the future based on A2, B1, and A1B scenarios, while ECMWF wind field was used to generate the wave characteristics in the control period. The results of these two 30-yearly wave modelings using SWAN model showed that the average wave power changes slightly in the future. Assessment of wave power spatial distribution showed that the reduction of the average wave power is more in the middle parts of the Persian Gulf. Investigation of wave power distribution in two coastal stations (Boushehr and Assalouyeh ports) indicated that the annual wave energy will decrease in both stations while the wave power distribution for different intervals of significant wave height and peak period will also change in Assalouyeh according to all scenarios.
Pipit: visualizing functional impacts of structural variations
Sakai, Ryo; Moisse, Matthieu; Reumers, Joke; Aerts, Jan
2013-01-01
Summary: Pipit is a gene-centric interactive visualization tool designed to study structural genomic variations. Through focusing on individual genes as the functional unit, researchers are able to study and generate hypotheses on the biological impact of different structural variations, for instance, the deletion of dosage-sensitive genes or the formation of fusion genes. Pipit is a cross-platform Java application that visualizes structural variation data from Genome Variation Format files. Availability: Executables, source code, sample data, documentation and screencast are available at https://bitbucket.org/biovizleuven/pipit. Contact: ryo.sakai@esat.kuleuven.be Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23803468
NASA Astrophysics Data System (ADS)
Wang, Li; Wu, Xiongbin; Ma, Ketao; Tian, Yun; Fei, Yuejun
2016-01-01
Directional wave spectra and integrated wave parameters can be derived from X-band radar sea surface images. A vessel on the sea surface has a significant influence on wave parameter inversions that can be seen as intensive backscatter speckles in X-band wave monitoring radar sea surface images. A novel algorithm to eliminate the interference of vessels in ocean wave height inversions from X-band wave monitoring radar is proposed. This algorithm is based on the characteristics of the interference. The principal components (PCs) of a sea surface image sequence are extracted using empirical orthogonal function (EOF) analysis. The standard deviation of the PCs is then used to identify vessel interference within the image sequence. To mitigate the interference, a suppression method based on a frequency domain geometric model is applied. The algorithm framework has been applied to OSMAR-X, a wave monitoring system developed by Wuhan University, based on nautical X-band radar. Several sea surface images captured on vessels by OSMAR-X are processed using the method proposed in this paper. Inversion schemes are validated by comparisons with data from in situ wave buoys. The root-mean-square error between the significant wave heights (SWH) retrieved from original interference radar images and those measured by the buoy is reduced by 0.25 m. The determinations of surface gravity wave parameters, in particular SWH, confirm the applicability of the proposed method.
The impact of heat waves on children's health: a systematic review
NASA Astrophysics Data System (ADS)
Xu, Zhiwei; Sheffield, Perry E.; Su, Hong; Wang, Xiaoyu; Bi, Yan; Tong, Shilu
2014-03-01
Young children are thought to be particularly sensitive to heat waves, but relatively less research attention has been paid to this field to date. A systematic review was conducted to elucidate the relationship between heat waves and children's health. Literature published up to August 2012 were identified using the following MeSH terms and keywords: "heatwave", "heat wave", "child health", "morbidity", "hospital admission", "emergency department visit", "family practice", "primary health care", "death" and "mortality". Of the 628 publications identified, 12 met the selection criteria. The existing literature does not consistently suggest that mortality among children increases significantly during heat waves, even though infants were associated with more heat-related deaths. Exposure to heat waves in the perinatal period may pose a threat to children's health. Pediatric diseases or conditions associated with heat waves include renal disease, respiratory disease, electrolyte imbalance and fever. Future research should focus on how to develop a consistent definition of a heat wave from a children's health perspective, identifying the best measure of children's exposure to heat waves, exploring sensitive outcome measures to quantify the impact of heat waves on children, evaluating the possible impacts of heat waves on children's birth outcomes, and understanding the differences in vulnerability to heat waves among children of different ages and from different income countries. Projection of the children's disease burden caused by heat waves under climate change scenarios, and development of effective heat wave mitigation and adaptation strategies that incorporate other child protective health measures, are also strongly recommended.
The impact of heat waves on children's health: a systematic review.
Xu, Zhiwei; Sheffield, Perry E; Su, Hong; Wang, Xiaoyu; Bi, Yan; Tong, Shilu
2014-03-01
Young children are thought to be particularly sensitive to heat waves, but relatively less research attention has been paid to this field to date. A systematic review was conducted to elucidate the relationship between heat waves and children's health. Literature published up to August 2012 were identified using the following MeSH terms and keywords: "heatwave", "heat wave", "child health", "morbidity", "hospital admission", "emergency department visit", "family practice", "primary health care", "death" and "mortality". Of the 628 publications identified, 12 met the selection criteria. The existing literature does not consistently suggest that mortality among children increases significantly during heat waves, even though infants were associated with more heat-related deaths. Exposure to heat waves in the perinatal period may pose a threat to children's health. Pediatric diseases or conditions associated with heat waves include renal disease, respiratory disease, electrolyte imbalance and fever. Future research should focus on how to develop a consistent definition of a heat wave from a children's health perspective, identifying the best measure of children's exposure to heat waves, exploring sensitive outcome measures to quantify the impact of heat waves on children, evaluating the possible impacts of heat waves on children's birth outcomes, and understanding the differences in vulnerability to heat waves among children of different ages and from different income countries. Projection of the children's disease burden caused by heat waves under climate change scenarios, and development of effective heat wave mitigation and adaptation strategies that incorporate other child protective health measures, are also strongly recommended. PMID:23525899
Colombian ocean waves and coasts modeled by special functions
NASA Astrophysics Data System (ADS)
Duque Tisns, Simn
2013-06-01
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.
Impact wave deposits provide new constraints on the location of the K/T boundary impact
NASA Technical Reports Server (NTRS)
Hildebrand, A. R.; Boynton, W. V.
1988-01-01
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.
Modelling storm development and the impact when introducing waves, sea spray and heat fluxes
NASA Astrophysics Data System (ADS)
Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik
2015-04-01
In high wind speed conditions, sea spray generated due to intensity breaking waves have big influence on the wind stress and heat fluxes. Measurements show that drag coefficient will decrease in high wind speed. Sea spray generation function (SSGF), an important term of wind stress parameterization in high wind speed, usually treated as a function of wind speed/friction velocity. In this study, we introduce a wave state depended SSGG and wave age depended Charnock number into a high wind speed wind stress parameterization (Kudryavtsev et al., 2011; 2012). The proposed wind stress parameterization and sea spray heat fluxes parameterization from Andreas et al., (2014) were applied to an atmosphere-wave coupled model to test on four storm cases. Compared with measurements from the FINO1 platform in the North Sea, the new wind stress parameterization can reduce the forecast errors of wind in high wind speed range, but not in low wind speed. Only sea spray impacted on wind stress, it will intensify the storms (minimum sea level pressure and maximum wind speed) and lower the air temperature (increase the errors). Only the sea spray impacted on the heat fluxes, it can improve the model performance on storm tracks and the air temperature, but not change much in the storm intensity. If both of sea spray impacted on the wind stress and heat fluxes are taken into account, it has the best performance in all the experiment for minimum sea level pressure and maximum wind speed and air temperature. Andreas, E. L., Mahrt, L., and Vickers, D. (2014). An improved bulk air-sea surface flux algorithm, including spray-mediated transfer. Quarterly Journal of the Royal Meteorological Society. Kudryavtsev, V. and Makin, V. (2011). Impact of ocean spray on the dynamics of the marine atmospheric boundary layer. Boundary-layer meteorology, 140(3):383-410. Kudryavtsev, V., Makin, V., and S, Z. (2012). On the sea-surface drag and heat/mass transfer at strong winds. Technical report, Royal Netherlands Meteorological Institute.
The effect of wave function orthogonality on the simultaneous ionization and excitation of helium
NASA Astrophysics Data System (ADS)
Liu, Li-Juan; Jia, Chang-Chun; Zhang, Li-Min; Chen, Jiao-Jiao; Chen, Zhang-Jin
2013-10-01
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.
Stress wave propagation in a composite beam subjected to transverse impact.
Lu, Wei-Yang; Song, Bo; Jin, Huiqing
2010-08-01
Composite materials, particularly fiber reinforced plastic composites, have been extensively utilized in many military and industrial applications. As an important structural component in these applications, the composites are often subjected to external impact loading. It is desirable to understand the mechanical response of the composites under impact loading for performance evaluation in the applications. Even though many material models for the composites have been developed, experimental investigation is still needed to validate and verify the models. It is essential to investigate the intrinsic material response. However, it becomes more applicable to determine the structural response of composites, such as a composite beam. The composites are usually subjected to out-of-plane loading in applications. When a composite beam is subjected to a sudden transverse impact, two different kinds of stress waves, longitudinal and transverse waves, are generated and propagate in the beam. The longitudinal stress wave propagates through the thickness direction; whereas, the propagation of the transverse stress wave is in-plane directions. The longitudinal stress wave speed is usually considered as a material constant determined by the material density and Young's modulus, regardless of the loading rate. By contrast, the transverse wave speed is related to structural parameters. In ballistic mechanics, the transverse wave plays a key role to absorb external impact energy [1]. The faster the transverse wave speed, the more impact energy dissipated. Since the transverse wave speed is not a material constant, it is not possible to be calculated from stress-wave theory. One can place several transducers to track the transverse wave propagation. An alternative but more efficient method is to apply digital image correlation (DIC) to visualize the transverse wave propagation. In this study, we applied three-pointbending (TPB) technique to Kolsky compression bar to facilitate dynamic transverse loading on a glass fiber/epoxy composite beam. The high-speed DIC technique was employed to study the transverse wave propagation.
Probing dissociative molecular dications by mapping vibrational wave functions
Puettner, R.; Sekushin, V.; Kaindl, G.; Arion, T.; Lischke, T.; Mucke, M.; Hergenhahn, U.; Foerstel, M.; Bradshaw, A. M.
2011-04-15
We present high-resolution photoelectron-Auger-electron coincidence spectra of methane (CH{sub 4}). Since the vibrational structure in the photoelectron spectrum is resolved, the Auger spectra corresponding to different vibrational levels can be separated. The seven final states of CH{sub 4}{sup 2+} are either dissociative or metastable, but in any case are populated in a repulsive part of their potential-energy curve via the Auger decay. The Auger line shapes can therefore be obtained by mapping the vibrational wave functions of the core-hole state into energy space. We have implemented this connection in the data analysis. By simultaneously fitting the different Auger spectra, detailed information on the energies of the dicationic states and their repulsive potential-energy curves is derived.
Semiclassical-wave-function perspective on high-harmonic generation
NASA Astrophysics Data System (ADS)
Mauger, François; Abanador, Paul M.; Lopata, Kenneth; Schafer, Kenneth J.; Gaarde, Mette B.
2016-04-01
We introduce a semiclassical-wave-function (SCWF) model for strong-field physics and attosecond science. When applied to high-harmonic generation (HHG), this formalism allows one to show that the natural time-domain separation of the contribution of ionization, propagation, and recollisions to the HHG process leads to a frequency-domain factorization of the harmonic yield into these same contributions, for any choice of atomic or molecular potential. We first derive the factorization from the natural expression of the dipole signal in the temporal domain by using a reference system, as in the quantitative rescattering (QRS) formalism [J. Phys. B 43, 122001 (2010), 10.1088/0953-4075/43/12/122001]. Alternatively, we show how the trajectory component of the SCWF can be used to express the factorization, which also allows one to attribute individual contributions to the spectrum to the underlying trajectories.
Human brain networks function in connectome-specific harmonic waves.
Atasoy, Selen; Donnelly, Isaac; Pearson, Joel
2016-01-01
A key characteristic of human brain activity is coherent, spatially distributed oscillations forming behaviour-dependent brain networks. However, a fundamental principle underlying these networks remains unknown. Here we report that functional networks of the human brain are predicted by harmonic patterns, ubiquitous throughout nature, steered by the anatomy of the human cerebral cortex, the human connectome. We introduce a new technique extending the Fourier basis to the human connectome. In this new frequency-specific representation of cortical activity, that we call 'connectome harmonics', oscillatory networks of the human brain at rest match harmonic wave patterns of certain frequencies. We demonstrate a neural mechanism behind the self-organization of connectome harmonics with a continuous neural field model of excitatory-inhibitory interactions on the connectome. Remarkably, the critical relation between the neural field patterns and the delicate excitation-inhibition balance fits the neurophysiological changes observed during the loss and recovery of consciousness. PMID:26792267
Human brain networks function in connectome-specific harmonic waves
Atasoy, Selen; Donnelly, Isaac; Pearson, Joel
2016-01-01
A key characteristic of human brain activity is coherent, spatially distributed oscillations forming behaviour-dependent brain networks. However, a fundamental principle underlying these networks remains unknown. Here we report that functional networks of the human brain are predicted by harmonic patterns, ubiquitous throughout nature, steered by the anatomy of the human cerebral cortex, the human connectome. We introduce a new technique extending the Fourier basis to the human connectome. In this new frequency-specific representation of cortical activity, that we call ‘connectome harmonics', oscillatory networks of the human brain at rest match harmonic wave patterns of certain frequencies. We demonstrate a neural mechanism behind the self-organization of connectome harmonics with a continuous neural field model of excitatory–inhibitory interactions on the connectome. Remarkably, the critical relation between the neural field patterns and the delicate excitation–inhibition balance fits the neurophysiological changes observed during the loss and recovery of consciousness. PMID:26792267
Finite temperature wave-function renormalization, a comparative analysis
Chapman, I.A.
1996-12-31
We compare two competing theories regarding finite temperature wave-function corrections for the process H {r_arrow} e{sup +}e{sup {minus}} and for n + {nu} {r_arrow} p + e{sup {minus}} and related processes of interest for primordial nucleosynthesis. Although the two methods are distinct (as shown in H {r_arrow} e{sup +}e{sup {minus}}) they yield the same finite temperature correction for all n {r_arrow} p and p {r_arrow} n processes. Both methods yield an increase in the He/H ratio of 0.01% due to finite temperature renormalization rather than a decrease of 0.16% as previously predicted. 6 refs., 3 figs.
Topological wave functions and the 4D-5D lift
NASA Astrophysics Data System (ADS)
Gao, Peng; Pioline, Boris
2008-07-01
We revisit the holomorphic anomaly equations satisfied by the topological string amplitude from the perspective of the 4D-5D lift, in the context of ``magic'' Script N = 2 supergravity theories. In particular, we interpret the Gopakumar-Vafa relation between 5D black hole degeneracies and the topological string amplitude as the result of a canonical transformation from 4D to 5D charges. Moreover we use the known Bekenstein-Hawking entropy of 5D black holes to constrain the asymptotic behavior of the topological wave function at finite topological coupling but large Kähler classes. In the process, some subtleties in the relation between 5D black hole degeneracies and the topological string amplitude are uncovered, but not resolved. Finally we extend these considerations to the putative one-parameter generalization of the topological string amplitude, and identify the canonical transformation as a Weyl reflection inside the 3D duality group.
Orientation dynamics of asymmetric rotors using random phase wave functions
NASA Astrophysics Data System (ADS)
Kallush, Shimshon; Fleischer, Sharly
2015-06-01
Intense terahertz-frequency pulses induce coherent rotational dynamics and orientation of polar molecular ensembles. Exact numerical methods for rotational dynamics at room temperature are computationally not feasible for the vast majority of molecular rotors: the asymmetric top molecules at ambient temperatures. We exemplify the use of random phase wave functions (RPWFs) by calculating the terahertz-induced rotational dynamics of sulfur dioxide at ambient temperatures and high-field strengths and show that the RPWF method gains efficiency with the increase in temperature and in the terahertz-field strengths. The present method provides wide-ranging computational access to rotational dynamical responses of molecules at experimental conditions that are far beyond the reach of exact numerical methods.
Dominant partition method. [based on a wave function formalism
NASA Technical Reports Server (NTRS)
Dixon, R. M.; Redish, E. F.
1979-01-01
By use of the L'Huillier, Redish, and Tandy (LRT) wave function formalism, a partially connected method, the dominant partition method (DPM) is developed for obtaining few body reductions of the many body problem in the LRT and Bencze, Redish, and Sloan (BRS) formalisms. The DPM maps the many body problem to a fewer body one by using the criterion that the truncated formalism must be such that consistency with the full Schroedinger equation is preserved. The DPM is based on a class of new forms for the irreducible cluster potential, which is introduced in the LRT formalism. Connectivity is maintained with respect to all partitions containing a given partition, which is referred to as the dominant partition. Degrees of freedom corresponding to the breakup of one or more of the clusters of the dominant partition are treated in a disconnected manner. This approach for simplifying the complicated BRS equations is appropriate for physical problems where a few body reaction mechanism prevails.
Early heat waves over Italy and their impacts on durum wheat yields
NASA Astrophysics Data System (ADS)
Fontana, G.; Toreti, A.; Ceglar, A.; De Sanctis, G.
2015-07-01
In the last decades the Euro-Mediterranean region has experienced an increase in extreme temperature events such as heat waves. These extreme weather conditions can strongly affect arable crop growth and final yields. Here, early heat waves over Italy from 1995 to 2013 are identified and characterised and their impact on durum wheat yields is investigated. As expected, results confirm the impact of the 2003 heat wave and highlight a high percentage of concurrence of early heat waves and significant negative yield anomalies in 13 out of 39 durum wheat production areas. In south-eastern Italy (the most important area for durum wheat production), the percentage of concurrent events exceeds 80 %.
Early heat waves over Italy and their impacts on durum wheat yields
NASA Astrophysics Data System (ADS)
Fontana, G.; Toreti, A.; Ceglar, A.; De Sanctis, G.
2015-05-01
In the last decades the Euro-Mediterranean region has experienced an increase in extreme temperature events such as heat waves. These extreme weather conditions can strongly affect arable crop growth and final yields. Here, early heat waves over Italy from 1995 to 2013 are identified and characterised and their impact on durum wheat yields is investigated. As expected, results confirm the impact of the 2003 heat waves and highlight a high percentage of concurrence of early heat waves and significant negative yield anomalies in 13 out of 39 durum wheat production areas. In south-eastern Italy (the most important area for durum wheat production), the percentage of concurrent events exceeds 80%.
Impact damage detection in sandwich composite structures using Lamb waves and laser vibrometry
NASA Astrophysics Data System (ADS)
Lamboul, B.; Passilly, B.; Roche, J.-M.; Osmont, D.
2013-01-01
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.
Impact of Autocorrelation on Functional Connectivity
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.
2014-01-01
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
Impact of grouping on growth of ocean waves
NASA Astrophysics Data System (ADS)
Drullion, F.; Sajjadi, S.; Hunt, J.
2012-12-01
The problem of growth of ocean waves by wind has been considered many times during the last fifty years but many aspect of the phenomenon is still not understood. It is commonly assumed that the growth of waves by wind is mainly driven by Miles inviscid mechanism, which assumes that the critical layer is confined inside the viscous sublayer. In this study we are considering the influence of grouping on the growth of ocean waves induced by wind. For this a finite volume computational model for a two dimensional turbulent shear flow of air over a moving wave group was developed. Numerical simulations involving different wave groups (different heights, different number of waves in the group, different shapes of waves) as well as different wind velocities, were carried. Our attention is focused on the disturbed air flow right above the surface of the wave and its effects on the flow structure in the vicinity of the critical layer. We Show that the critical layer height varies above the group of waves and is not confined to the viscous sublayer.
Ezzedine, Souheil M.; Lomov, Ilya; Miller, Paul L.; Dennison, Deborah S.; Dearborn, David S.; Antoun, Tarabay H.
2015-05-19
As part of a larger effort involving members of several other organizations, we have conducted numerical simulations in support of emergency-response exercises of postulated asteroid ocean impacts. We have addressed the problem from source (asteroid entry) to ocean impact (splash) to wave generation, propagation and interaction with the U.S. shoreline. We simulated three impact sites. The first site is located off the east coast by Maryland's shoreline. The second site is located off of the West coast, the San Francisco bay. The third set of sites are situated in the Gulf of Mexico. Asteroid impacts on the ocean surface aremore » conducted using LLNL's hydrocode GEODYN to create the impact wave source for the shallow water wave propagation code, SWWP, a shallow depth averaged water wave code.« less
Ezzedine, Souheil M.; Lomov, Ilya; Miller, Paul L.; Dennison, Deborah S.; Dearborn, David S.; Antoun, Tarabay H.
2015-05-19
As part of a larger effort involving members of several other organizations, we have conducted numerical simulations in support of emergency-response exercises of postulated asteroid ocean impacts. We have addressed the problem from source (asteroid entry) to ocean impact (splash) to wave generation, propagation and interaction with the U.S. shoreline. We simulated three impact sites. The first site is located off the east coast by Maryland's shoreline. The second site is located off of the West coast, the San Francisco bay. The third set of sites are situated in the Gulf of Mexico. Asteroid impacts on the ocean surface are conducted using LLNL's hydrocode GEODYN to create the impact wave source for the shallow water wave propagation code, SWWP, a shallow depth averaged water wave code.
NASA Astrophysics Data System (ADS)
Restrepo, Doriam; Gómez, Juan David; Jaramillo, Juan Diego
2014-09-01
We present a closed-form frequency-wave number ( ω - k) Green's function for a layered, elastic half-space under SH wave propagation. It is shown that for every ( ω - k) pair, the fundamental solution exhibits two distinctive features: (1) the original layered system can be reduced to a system composed by the uppermost superficial layer over an equivalent half-space; (2) the fundamental solution can be partitioned into three different fundamental solutions, each one carrying out a different physical interpretation, i.e., an equivalent half-space, source image impact, and dispersive wave effect, respectively. Such an interpretation allows the proper use of analytical and numerical integration schemes, and ensures the correct assessment of Cauchy principal value integrals. Our method is based upon a stiffness-matrix scheme, and as a first approach we assume that observation points and the impulsive SH line-source are spatially located within the uppermost superficial layer. We use a discrete wave number boundary element strategy to test the benefits of our fundamental solution. We benchmark our results against reported solutions for an infinitely long circular canyon subjected to oblique incident SH waves within a homogeneous half-space. Our results show an almost exact agreement with previous studies. We further shed light on the impact of horizontal strata by examining the dynamic response of the circular canyon to oblique incident SH waves under different layered half-space configurations and incident angles. Our results show that modifications in the layering structure manifest by larger peak ground responses, and stronger spatial variability due to interactions of the canyon geometry with trapped Love waves in combination with impedance contrast effects.
The impact energy of a moored tanker under the action of regular waves
Yu-Cheng Li
1982-09-01
The influence that factors such as mooring line conditions, fender arrangements, dolphin arrangements, degree of ship loading, waves of long period, wave direction, and wind on the impact energy of a moored tanker were studied. Based on systematic test data, a semi-empirical formula was developed to calculate the impact energy of the moored ship on the berthing facilities under the action of regular waves. It was shown by experiment that this method is suitable for calculating the impact energy of moored ships of capacities as great as 200 X 10/sup 3/ t.
The atom in a molecule: A wave function approach
NASA Astrophysics Data System (ADS)
Rychlewski, Jacek; Parr, Robert G.
1986-02-01
Given a homonuclear diatomic molecule AB with an even number of electrons N in the state ψ. What is the state of atom A in the molecule? Using the lemma that <ψ‖HA ‖ψ>/<ψ‖ψ>≥E0A where HA is the Hamiltonian for atom A only, having NA =N/2 electrons, and E0A is the ground state energy of A, the following general definition is suggested and quantitatively tested for the hydrogen atom in the hydrogen molecule. Define N-electron functions ψA and ψB by ‖ψ‖2= 1/2 [‖ψA‖2+‖ψB‖2], ψA =ψ[1+F]1/2, and ψB =ψ[1-F]1/2, with ψA, ψB, and ψ all normalized and F a function symmetric with respect to electron interchange. Then ρ=ρA+ρB and F can be determined to minimize the promotion energy <ψA‖ĤA‖ψA>-E0A. Calculations are performed for the H2 ground state and b3∑+u excited state, as functions R, employing accurate wave functions including correlation. For the ground state at the equilibrium internuclear distance, the promotion energy is found to be 0.0447 a.u. or 28 kcal/mol. The electron density for the atom in the molecule is examined, and extensions to heteronuclear and polyatomic molecules briefly discussed.
Bohmian Conditional Wave Functions (and the status of the quantum state)
NASA Astrophysics Data System (ADS)
Norsen, Travis
2016-03-01
The de Broglie - Bohm pilot-wave theory - uniquely among realistic candidate quantum theories - allows a straightforward and simple definition of the wave function of a subsystem of some larger system (such as the entire universe). Such sub-system wave functions are called “Conditional Wave Functions” (CWFs). Here we explain this concept and indicate the CWF's role in the Bohmian explanation of the usual quantum formalism, and then develop (and motivate) the more speculative idea that something like single-particle wave functions could replace the (ontologically problematical) universal wave function in some future, empirically adequate, pilot-wave-type theory. Throughout the presentation is pedagogical and points are illustrated with simple toy models.
Assessing the orbital selective Mott transition with variational wave functions
NASA Astrophysics Data System (ADS)
Tocchio, Luca F.; Arrigoni, Federico; Sorella, Sandro; Becca, Federico
2016-03-01
We study the Mott metal-insulator transition in the two-band Hubbard model with different hopping amplitudes t 1 and t 2 for the two orbitals on the two-dimensional square lattice by using non-magnetic variational wave functions, similarly to what has been considered in the limit of infinite dimensions by dynamical mean-field theory. We work out the phase diagram at half filling (i.e. two electrons per site) as a function of R={{t}2}/{{t}1} and the on-site Coulomb repulsion U, for two values of the Hund’s coupling J = 0 and J/U = 0.1. Our results are in good agreement with previous dynamical mean-field theory calculations, demonstrating that the non-magnetic phase diagram is only slightly modified from infinite to two spatial dimensions. Three phases are present: a metallic one, for small values of U, where both orbitals are itinerant; a Mott insulator, for large values of U, where both orbitals are localized because of the Coulomb repulsion; and the so-called orbital-selective Mott insulator (OSMI), for small values of R and intermediate Us, where one orbital is localized while the other one is still itinerant. The effect of the Hund’s coupling is two-fold: on one side, it favors the full Mott phase over the OSMI; on the other side, it stabilizes the OSMI at larger values of R.
Riemann {zeta} function from wave-packet dynamics
Mack, R.; Schleich, W. P.; Dahl, J. P.; Moya-Cessa, H.; Strunz, W. T.; Walser, R.
2010-09-15
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.
Propagating two-particle reduced density matrices without wave functions
NASA Astrophysics Data System (ADS)
Lackner, Fabian; Březinová, Iva; Sato, Takeshi; Ishikawa, Kenichi L.; Burgdörfer, Joachim
2015-02-01
Describing time-dependent many-body systems where correlation effects play an important role remains a major theoretical challenge. In this paper we develop a time-dependent many-body theory that is based on the two-particle reduced density matrix (2-RDM). We present a closed equation of motion for the 2-RDM by developing a reconstruction functional for the three-particle reduced density matrix (3-RDM) that preserves norm, energy, and spin symmetries during time propagation. We show that approximately enforcing N -representability during time evolution is essential for achieving stable solutions. As a prototypical test case which features long-range Coulomb interactions we employ the one-dimensional model for lithium hydride (LiH) in strong infrared laser fields. We probe both one-particle observables such as the time-dependent dipole moment and two-particle observables such as the pair density and mean electron-electron interaction energy. Our results are in very good agreement with numerically exact solutions for the N -electron wave function obtained from the multiconfigurational time-dependent Hartree-Fock method.
Assessing the orbital selective Mott transition with variational wave functions.
Tocchio, Luca F; Arrigoni, Federico; Sorella, Sandro; Becca, Federico
2016-03-16
We study the Mott metal-insulator transition in the two-band Hubbard model with different hopping amplitudes t 1 and t 2 for the two orbitals on the two-dimensional square lattice by using non-magnetic variational wave functions, similarly to what has been considered in the limit of infinite dimensions by dynamical mean-field theory. We work out the phase diagram at half filling (i.e. two electrons per site) as a function of [Formula: see text] and the on-site Coulomb repulsion U, for two values of the Hund's coupling J = 0 and J/U = 0.1. Our results are in good agreement with previous dynamical mean-field theory calculations, demonstrating that the non-magnetic phase diagram is only slightly modified from infinite to two spatial dimensions. Three phases are present: a metallic one, for small values of U, where both orbitals are itinerant; a Mott insulator, for large values of U, where both orbitals are localized because of the Coulomb repulsion; and the so-called orbital-selective Mott insulator (OSMI), for small values of R and intermediate Us, where one orbital is localized while the other one is still itinerant. The effect of the Hund's coupling is two-fold: on one side, it favors the full Mott phase over the OSMI; on the other side, it stabilizes the OSMI at larger values of R. PMID:26881997
P-wave Receiver Functions reveal the Bohemian Massif crust
NASA Astrophysics Data System (ADS)
Kampfova Exnerova, Hana; Plomerova, Jaroslava; Vecsey, Ludek
2015-04-01
In this study we present initial results of P-wave Receiver Functions (RF) calculated from broad-band waveforms of teleseismic events recorded by temporary and permanent stations in the Bohemian Massif (BM, Central Europe). Temporary arrays BOHEMA I (2001-2003), BOHEMA II (2004-2005) and BOHEMA III (2005-2006) operated during passive seismic experiments oriented towards studying velocity structure of the lithosphere and the upper mantle. Receiver Functions show relative response of the Earth structure under a seismic station and nowadays represent frequently-used method to retrieve structure of the crust, whose knowledge is needed in various studies of the upper mantle. The recorded waveforms are composites of direct P and P-to-S converted waves that reverberate in the structure beneath the receiver (Ammon, 1997). The RFs are sensitive to seismic velocity contrast and are thus suited to identifying velocity discontinuities in the crust, including the Mohorovi?i? discontinuity (Moho). Relative travel-time delays of the converted phases detected in the RFs are transformed into estimates of discontinuity depths assuming external information on the vp/vs and P velocity. To evaluate RFs we use the Multiple-taper spectral correlation (MTC) method (Park and Levin, 2000) and process signals from teleseismic events at epicentral distances of 30 - 100 with magnitude Mw > 5.5. Recordings are filtered with Butterworth band-pass filter of 2 - 8 s. To select automatically signals which are strong enough, we calculate signal-to-noise ratios (SNR) in two steps. In the first step we calculate SNR for signals from intervals (-1s, 3s)/(-10s, -2s), where P-arrival time represent time zero. In the second step we broaden the intervals and calculate SNR for (-1s, 9s)/(-60s, -2s). We also employ forward modelling of the RFs using Interactive Receiver Functions Forward Modeller (IRFFM) (Tkal?i? et al., 2010) to produce, in the first step, one-dimensional velocity models under individual seismic station. Stacked traces of the RFs show strong conversions with positive polarity (indicating a velocity increase across the discontinuity) between 3.3 and 4.5 s after the P-wave arrival at almost all stations. We relate these pulses to conversions at the Moho discontinuity. Assuming a constant crustal vp/vs ratio (1.73) and average crustal velocity vp=6.3 km/s for all stations, analogically to Geissler et al (2012), we multiply the evaluated Ps delay times by factor of 8.3 km/s and estimate the Moho beneath the Bohemian Massif at depths between 27 and 37 km. The crust is thinnest in the western part of the BM, beneath the SW end of the Eger Rift. The Moldanubian part of the BM exhibits the thickest crust. At most of the stations we also see one or two intra-crustal conversions, sometimes stronger than that related to the Moho. Several stations exhibit significant variations of the RF with back-azimuth. The aim of this study is to update existing three dimensional P-velocity crustal model of the Bohemian Massif (Karousov et al., 2012) compiled from control-source seismic results.
The Environmental Impact of a Wave Dragon Array Operating in the Black Sea
Rusu, Eugen
2013-01-01
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
The environmental impact of a Wave Dragon array operating in the Black Sea.
Diaconu, Sorin; Rusu, Eugen
2013-01-01
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
[Dynamics of bacterial population waves in relation to the function of chemotaxis response].
Aslanidi, G V; Dzheliadin, T P; Shakhbazian, V Iu; Tsyganova, V G; Tsyganov, M A; Ivanitskiĭ, G R
2009-01-01
The time of formation and rate of bacterial population waves as a function of substrate concentration has been investigated. It was shown both theoretically and in experiment that the time of wave formation increases with substrate concentration. At the same time, the rate of wave propagation decreases at relatively high substrate concentrations. A comparative analysis of the dynamics of bacterial population waves in different chemotaxis responses was carried out in in silico experiments with the Keller-Segel model. PMID:19334631
Green's function for a metamaterial superlens: Evanescent wave in the image
NASA Astrophysics Data System (ADS)
Li, Wei; Jiang, Xunya
2012-04-01
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.
A technique for generating shear waves in cylindrical shells under radial impact
NASA Technical Reports Server (NTRS)
Blum, A.; Mortimer, R. W.; Rose, J. L.
1974-01-01
Experimental techniques are developed to study and measure the shear-wave velocity in an aluminum cylindrical shell subjected to a radial impact. The radial impact is obtained by exploding an electrical detonator inserted in plastic plugs mounted on the end of the shell. Strain gages, mounted on the outside surface of the shell at various axial locations, are used to obtain oscilloscope traces from which the shear-wave velocity can be calculated.
Ben Salah, Issam; Ben Amor, Morched; Ben Ghozlen, Mohamed Hédi
2015-08-01
Numerical examples for wave propagation in a three-layer structure have been investigated for both electrically open and shorted cases. The first order differential equations are solved by both methods ODE and Stiffness matrix. The solutions are used to study the effects of thickness and gradient coefficient of soft middle layer on the phase velocity and on the electromechanical coupling factor. We demonstrate that the electromechanical coupling factor is substantially increased when the equivalent thickness is in the order of the wavelength. The effects of gradient coefficients are plotted for the first mode when electrical and mechanical gradient variations are applied separately and altogether. The obtained deviations in comparison with the ungraded homogenous film are plotted with respect to the dimensionless wavenumber. The impact related to the gradient coefficient of the soft middle layer, on the mechanical displacement and the Poynting vector, is carried out. The numericals results are illustrated by a set of appropriate curves related to various profiles. The obtained results set guidelines not only for the design of high-performance surface acoustic wave (SAW) devices, but also for the measurement of material properties in a functionally graded piezoelectric layered system using Love waves. PMID:25964239
Quantum anti-Zeno effect without wave function reduction
Ai, Qing; Xu, Dazhi; Yi, Su; Kofman, A. G.; Sun, C. P.; Nori, Franco
2013-01-01
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.
Wave-functions overlap in stoichiometric lanthanide laser crystals
NASA Astrophysics Data System (ADS)
Petrov, Dimitar N.
2015-10-01
Two-center overlap integrals (TCOIs), < 4 f | 4 f > of symmetry types σ, π, δ, φ, < 2 s | 4 f > , < 2 p | 4 f > σ, and < 2 p | 4 f > π, have been computed for 11 stoichiometric lasing lanthanide compounds: PrP4O15, NdP5O14, NdLiP4O12, NdAl3(BO3)4, NdNa5(WO4)4, NdK3(PO4)2, NdKP4O12, HoF3, Ho3Al5O12, Er3Al5O12, and ErP5O14. Four-term (4-t) and six-term (6-t) SCF Slater-type orbitals have been employed for Ln3+ at mean distances Ln3+-Ln3+ and Ln3+-ligand. Different results for ion pair overlap have been obtained by using 4-t or 6-t wave functions of Pr3+ and Nd3+. The TCOIs have been correlated with measured lifetimes of laser transitions of Pr3+, Nd3+, Ho3+, and Er3+ in the mentioned crystals.
Newton force from wave function collapse: speculation and test
NASA Astrophysics Data System (ADS)
Diósi, Lajos
2014-04-01
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.
Impacts of wave spreading and multidirectional waves on estimating Stokes drift
NASA Astrophysics Data System (ADS)
Webb, A.; Fox-Kemper, B.
2015-12-01
The Stokes drift, and its leading-order approximation, for a random sea depend upon the interaction of different wave groups and the process of wave spreading. Here Stokes drift direction and magnitude from prescribed spectra, local observational buoy data, and global model WAVEWATCH III output are used to analyze approximations of Stokes drift for directional random seas in deep water. To facilitate analysis, a new approximation is defined to incorporate the systematic effects of wave spreading. Stokes drift is typically overestimated by ignoring these effects or by ignoring directional differences in swell and wind seas. These two errors are differentiated and found to be largely uncorrelated. These errors depend strongly on depth, with deeper Stokes drift favoring narrow-banded swell and shallower Stokes drift favoring wind seas. Results are consistent among the data examined. Mean Stokes drift magnitude reductions from wave spreading and multidirectional wave effects alone are 14-20% and 7-23% respectively, giving a combined reduction of 20-40% versus unidirectional waves, depending on wave age and depth. Approximations that do not include these reductions however, will on average overestimate Stokes drift by 16-26%, 26-43%, and 45-71% respectively. In addition to magnitude, the direction of Stokes drift is also affected and multidirectional waves generate a directional veer with depth: the 30/60/90% confidence intervals are bounded (approximately) by ± 0.12/0.28/0.84 radians (± 7/16/48 deg) at the surface, with smaller intervals at depth. Complementary depth-integrated approximations are also investigated and directional effects are similar with depth-dependent subsurface results. Furthermore, an optimized directional spread correction for the surface is nearly identical for global simulations and a buoy located at Ocean Weather Station P (50°N 145°W), and does not require directional wave spectrum data.
The function of 'brain waves': a cybernetic model of electroencephalography.
ben-Aaron, M
2003-01-01
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
Covariant nucleon wave function with S, D, and P-state components
Franz Gross, G. Ramalho, M. T. Pena
2012-05-01
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.
Attosecond photoemission dynamics encoded in real-valued continuum wave functions
NASA Astrophysics Data System (ADS)
Gaillac, Romain; Vacher, Morgane; Maquet, Alfred; Taïeb, Richard; Caillat, Jérémie
2016-01-01
The dynamics of photoemission is fully encoded in the continuum wave functions selected by the transitions. Using numerical simulations on simple benchmark models, we show how scattering phase shifts and photoemission delays can be retrieved from this unambiguously defined class of wave functions. In contrast with standard scattering waves inherited from collision theory, they are real-valued for one-photon transitions and provide a clear-cut interpretation of the delays recently discussed in the framework of attosecond science.
Impact of a coupled ocean wave-tide-circulation system on coastal modeling
NASA Astrophysics Data System (ADS)
Moon, Il-Ju
The impact of a coupled ocean wave-tide-circulation system on coastal modeling for wind waves, oceanic circulation, and water-mass simulation is investigated by coupling of two well-tested models: the third-generation wave model (WAVEWATCH-II) and the Princeton ocean model (POM). In this study, several numerical experiments in the Yellow and East China Sea (YECS) are performed for the ideal winter case and the typhoon Winnie case. In the coupled system, wind waves are influenced by both currents and sea level elevation induced by tides, storm surges, and oceanic circulation. Tides were the most influential factor in modulating mean wave characteristics in the YECS. The magnitude of the modulation of mean wave parameters at neap tides is found to be half that at spring tides. In the YECS the tides affect not only wind waves, but also seasonal circulation and water-mass distributions. Tides increase the bottom friction of the YECS significantly and this contributes to a change of winter current direction up to 60 °C in the YECS and a decrease of surface temperatures along the trough of the Yellow Sea up to 4 °C in winter. Tides in summer produce the strong vertical mixing in shallow regions. This leads to the formation of tidal fronts in a boundary between well-mixed and stratified regions and causes sea surface temperatures (SST) along the west coast of Korea decrease as much as 3 °C. Effects of ocean waves on coastal circulation and SST simulations are investigated considering wave-dependent stress, wave breaking parameterization, and Langmuir circulation under typhoon Winnie conditions. The results show that the wave-dependent stress, which is strongly dependent on wave age and relative position from storm center, as well as the wave breaking have the most significant impact on the SST distribution.
Impact of incident Mach wave on supersonic boundary layer
NASA Astrophysics Data System (ADS)
Vaganov, A. V.; Ermolaev, Yu. G.; Kolosov, G. L.; Kosinov, A. D.; Panina, A. V.; Semionov, N. V.; Yatskikh, A. A.
2016-01-01
Results of an experimental study of the excitation of high-intensity disturbances by a weak external shock wave in laminar boundary layer on flat-plate models with sharp and blunted leading edges at M = 2.5 are reported. The field of disturbances produced by a 2D sticker in turbulent boundary layer on the wall of wind-tunnel test section in the free stream is shown to have the form of an N-wave. It is found that, on the blunted plate, the intensity of pulsations produced by weak external shock waves in boundary layer several times exceeds the intensity of pulsations produced in boundary layer on the model with a sharp leading edge.
Impact of Phase Transitions on P Wave Velocities
D Weidner; L Li
2011-12-31
In regions where a high pressure phase is in equilibrium with a low pressure phase, the bulk modulus defined by the P-V relationship is greatly reduced. Here we evaluate the effect of such transitions on the P wave velocity. A model, where cation diffusion is the rate limiting factor, is used to project laboratory data to the conditions of a seismic wave propagating in the two-phase region. We demonstrate that for the minimum expected effect there is a significant reduction of the seismic velocity, as large as 10% over a narrow depth range.
Efficient and Flexible Computation of Many-Electron Wave Function Overlaps
2016-01-01
A new algorithm for the computation of the overlap between many-electron wave functions is described. This algorithm allows for the extensive use of recurring intermediates and thus provides high computational efficiency. Because of the general formalism employed, overlaps can be computed for varying wave function types, molecular orbitals, basis sets, and molecular geometries. This paves the way for efficiently computing nonadiabatic interaction terms for dynamics simulations. In addition, other application areas can be envisaged, such as the comparison of wave functions constructed at different levels of theory. Aside from explaining the algorithm and evaluating the performance, a detailed analysis of the numerical stability of wave function overlaps is carried out, and strategies for overcoming potential severe pitfalls due to displaced atoms and truncated wave functions are presented. PMID:26854874
Topological and entanglement properties of resonating valence bond wave functions
NASA Astrophysics Data System (ADS)
Poilblanc, Didier; Schuch, Norbert; Pérez-García, David; Cirac, J. Ignacio
2012-07-01
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.
NASA Astrophysics Data System (ADS)
Dugda, Mulugeta Tuji
Crust and upper mantle structure beneath eastern Africa has been investigated using receiver functions and surface wave dispersion measurements to understand the impact of the hotspot tectonism found there on the lithospheric structure of the region. In the first part of this thesis, I applied H-kappa stacking of receiver functions, and a joint inversion of receiver functions and Rayleigh wave group velocities to determine the crustal parameters under Djibouti. The two methods give consistent results. The crust beneath the GEOSCOPE station ATD has a thickness of 23+/-1.5 km and a Poisson's ratio of 0.31+/-0.02. Previous studies give crustal thickness beneath Djibouti to be between 8 and 10 km. I found it necessary to reinterprete refraction profiles for Djibouti from a previous study. The crustal structure obtained for ATD is similar to adjacent crustal structure in many other parts of central and eastern Afar. The high Poisson's ratio and Vp throughout most of the crust indicate a mafic composition, suggesting that the crust in Afar consists predominantly of new igneous rock emplaced during the late synrift stage where extension is accommodated within magmatic segments by diking. In the second part of this thesis, the seismic velocity structure of the crust and upper mantle beneath Ethiopia and Djibouti has been investigated by jointly inverting receiver functions and Rayleigh wave group velocities to obtain new constraints on the thermal structure of the lithosphere. Crustal structure from the joint inversion for Ethiopia and Djibouti is similar to previously published models. Beneath the Main Ethiopian Rift (MER) and Afar, the lithospheric mantle has a maximum shear wave velocity of 4.1-4.2 km/s and extends to a depth of at most 50 km. In comparison to the lithosphere away from the East African Rift System in Tanzania, where the lid extends to depths of ˜100-125 km and has a maximum shear velocity of 4.6 km/s, the mantle lithosphere under the Ethiopian Plateau appears to have been thinned by ˜30-50 km and the maximum shear wave velocity reduced by ˜0.3 km/s. Results from a 1D conductive thermal model suggest that the shear velocity structure of the lithosphere beneath the Ethiopian Plateau can be explained by a plume model, if a plume rapidly thinned the lithosphere by ˜30--50 km at the time of the flood basalt volcanism (c. 30 Ma), and if warm plume material has remained beneath the lithosphere since then. About 45-65% of the 1-1.5 km of plateau uplift in Ethiopia can be attributed to the thermally perturbed lithospheric structure. In the final part of this thesis, the shear-wave velocity structure of the crust and upper mantle beneath Kenya has been obtained from a joint inversion of receiver functions, and Rayleigh wave group and phase velocities. The crustal structure from the joint inversion is consistent with crustal structure published previously by different authors. The lithospheric mantle beneath the East African Plateau in Kenya is similar to the lithosphere under the East African Plateau in Tanzania. Beneath the Kenya Rift, the lithosphere extends to a depth of at most ˜75 km. The lithosphere under the Kenya Plateau is not perturbed when compared to the highly perturbed lithosphere beneath the Ethiopian Plateau. On the other hand, the lithosphere under the Kenya Rift is perturbed as compared to the Kenya Plateau or the rest of the East African Plateau, but is not as perturbed as the lithosphere beneath the Main Ethiopian Rift or the Afar. Although Kenya and Ethiopia have similar uplift and rifting histories, they have different volcanic histories. Much of Ethiopia has been affected by the Afar Flood Basalt volcanism, which may be the cause of this difference in lithospheric structure between these two regions.
Argonov, V. Yu.
2014-11-15
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.
IMPACTS OF URBANIZATION ON WATERSHED HYDROLOGIC FUNCTION
Technology Transfer Automated Retrieval System (TEKTRAN)
Although urbanization has a major impact on watershed hydrology, there have not been studies to quantify basic hydrological relationships are altered by the addition of impervious surfaces. The USDA-ARS and USEPA-ORD-NRMRL have initiated a pilot program to study the impacts of different extents and...
IMPACTS OF URBANIZATION ON WATERSHED HYDROLOGIC FUNCTION
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...
Wave propagation in graphite/epoxy laminates due to impact
NASA Technical Reports Server (NTRS)
Tan, T. M.; Sun, C. T.
1982-01-01
The low velocity impact response of graphite-epoxy laminates is investigated theoretically and experimentally. A nine-node isoparametric finite element in conjunction with an empirical contact law was used for the theoretical investigation. Flat laminates subjected to pendulum impact were used for the experimental investigation. Theoretical results are in good agreement with strain gage experimental data. The collective results of the investigation indicate that the theoretical procedure describes the impact response of the laminate up to about 150 in/sec. impact velocity.
Franz Gross, Alfred Stadler
2010-09-01
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.
Thermoelastic Stress in a Functionally Graded Infinite Plate with Electromagnetic Wave Absorption
NASA Astrophysics Data System (ADS)
Tian, Hong-Yan; Wang, Xing-Zhe; Zhou, You-He
2012-11-01
We present an analysis of thermal and thermoelastic behaviors of a functionally graded infinite plate taking into account electromagnetic wave absorption. To treat with the inhomogeneity of functionally graded wave-absorbing (FGWA) materials, the plate is approximated by subdividing it into thin homogeneous layers to solve the governing equations together with proper boundary and connecting conditions. The results illustrate that the FGWA plate is a broadband type absorber with electromagnetic wave absorption. By choosing proper material gradation character and the thickness of the FGWA plate, it is possible to obtain a good performance of electromagnetic wave absorption and thermoelastic stress characteristics.
Khan, Shehryar; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef; Odelius, Michael
2015-01-21
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 Odelius, Michael; Kubica-Misztal, Aleksandra; Kruk, Danuta; Kowalewski, Jozef
2015-01-21
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(H{sub 2}O){sup −}, Gd(III)DTPA(H{sub 2}O){sup 2−}, and Gd(III)(H{sub 2}O){sub 8}{sup 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.
Hadronic Spectra and Light-Front Wave Functions in Holographic QCD
Brodsky, Stanley J.; Teramond, Guy F. de
2006-05-26
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.
NASA Astrophysics Data System (ADS)
Farin, Maxime; Mangeney, Anne; Rosny, Julien de; Toussaint, Renaud; Sainte-Marie, Jacques; Shapiro, Nikolaï M.
2016-02-01
Estimating the energy lost in elastic waves during an impact is an important problem in seismology and in industry. We propose three complementary methods to estimate the elastic energy radiated by bead impacts on thin plates and thick blocks from the generated vibration. The first two methods are based on the direct wave front and are shown to be equivalent. The third method makes use of the diffuse regime. These methods are tested for laboratory experiments of impacts and are shown to give the same results, with error bars of 40 percent and 300 percent for impacts on a smooth plate and on a rough block, respectively. We show that these methods are relevant to establish the energy budget of an impact. On plates of glass and PMMA, the radiated elastic energy increases from 2 percent to almost 100 percent of the total energy lost as the bead diameter approaches the plate thickness. The rest of the lost energy is dissipated by viscoelasticity. For beads larger than the plate thickness, plastic deformation occurs and reduces the amount of energy radiated in the form of elastic waves. On a concrete block, the energy dissipation during the impact is principally inelastic because only 0.2-2 percent of the energy lost by the bead is transported by elastic waves. The radiated elastic energy estimated with the presented methods is quantitatively validated by Hertz's model of elastic impact.
Impact of cosmic neutrinos on the gravitational-wave background
Mangilli, Anna; Bartolo, Nicola; Matarrese, Sabino; Riotto, Antonio
2008-10-15
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.
NASA Technical Reports Server (NTRS)
Bourgeois, Joanne; Wiberg, Patricia L.
1988-01-01
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 scenarios for the K/T boundary event, then, tsunamis are expected, and where to look for them must be determined, and how to distinguish deposits from different tsunamis. Also, because tsunamis decrease in height as they move away from their source, the proximal effects will differ by perhaps orders of magnitude from distal effects. Data on the characteristics of tsunamis at their origin are scarce. Some observations exist for tsunamis generated by thermonuclear explosions and for seismogenic tsunamis, and experimental work was conducted on impact-generated tsunamis. All tsunamis of interest have wave-lengths of 0(100) km and thus behave as shallow-water waves in all ocean depths. Typical wave periods are 0(10 to 100) minutes. The effect of these tsunamis can be estimated in the marine and coastal realm by calculating boundary shear stresses (expressed as U*, the shear velocity). An event layer at the K/T boundary in Texas occurs in mid-shelf muds. Only a large, long-period wave with a wave height of 0(50) m, is deemed sufficient to have produced this layer. Such wave heights imply a nearby volcanic explosion on the scale of Krakatau or larger, or a nearby submarine landslide also of great size, or a bolide-water impact in the ocean.
The impact of tropospheric planetary wave variability on stratospheric ozone
McElroy, Michael B.; Schneider, Hans R.
2002-06-25
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.
Impact of wave action on the structure of material on the beach in Calypsobyen (Spitsbergen)
NASA Astrophysics Data System (ADS)
Mędrek, Karolina; Herman, Agnieszka; Moskalik, Mateusz; Rodzik, Jan; Zagórski, Piotr
2015-04-01
The research was conducted during the XXVI Polar Expedition of Maria Curie-Sklodowska University in Lublin on Spitsbergen. It involved recording water wave action in the Bellsund Strait, and taking daily photographs of the beach on its shore in Calypsobyen. The base of polar expeditions of UMCS, Calypsobyen, is located on the coast of Calypsostranda, developed by raised marine terraces. Weakly resistant Tertiary sandstones occur in the substrate, covered with glacigenic sediments and marine gravels. No skerries are encountered along this section of the accumulation coast. The shore is dominated by gravel deposits. The bottom slopes gently. The recording of wave action was performed from 8 July to 27 August 2014 by means of a pressure based MIDAS WTR Wave and Tide Recorder set at a depth of 10 m at a distance of about 1 km from the shore. The obtained data provided the basis for the calculation of the significant wave height, and the corresponding mean wave period . These parameters reflect wave energy and wave level, having a considerable impact on the dynamics of coastal processes and the type and grain size of sediments accumulated on the beach. Material consisting of medium gravel and seaweed appeared on the beach at high values of significant wave height and when the corresponding mean wave period showed average values. The contribution of fine, gravel-sandy material grew with an increase in mean period and a decrease in significant wave height. At maximum values of mean period and low values of significant wave height, the beach was dominated by well-sorted fine-grained gravel. The lowest mean periods resulted in the least degree of sorting of the sediment (from very coarse sand to medium gravel). The analysis of data from the wave and tide recorder set and their comparison with photographs of the beach suggest that wave action, and particularly wave energy manifested in significant wave height, has a considerable impact on the type and grain size of material occurring on the shore of the fjord. The mean period is mainly responsible for sorting out the sediment, and the size of gravels is associated with significant wave height. Project of National Science Centre no. DEC-2013/09/B/ST10/04141
Impacts of a spring heat wave on canopy processes in a northern hardwood forest.
Filewod, Ben; Thomas, Sean C
2014-02-01
Heat wave frequency, duration, and intensity are predicted to increase with global warming, but the potential impacts of short-term high temperature events on forest functioning remain virtually unstudied. We examined canopy processes in a forest in Central Ontario following 3 days of record-setting high temperatures (31–33 °C) that coincided with the peak in leaf expansion of dominant trees in late May 2010. Leaf area dynamics, leaf morphology, and leaf-level gas-exchange were compared to data from prior years of sampling (2002–2008) at the same site, focusing on Acer saccharum Marsh., the dominant tree in the region. Extensive shedding of partially expanded leaves was observed immediately following high temperature days, with A. saccharum losing ca. 25% of total leaf production but subsequently producing an unusual second flush of neoformed leaves. Both leaf losses and subsequent reflushing were highest in the upper canopy; however, retained preformed leaves and neoformed leaves showed reduced size, resulting in an overall decline in end-of-season leaf area index of 64% in A. saccharum, and 16% in the entire forest. Saplings showed lower leaf losses, but also a lower capacity to reflush relative to mature trees. Both surviving preformed and neoformed leaves had severely depressed photosynthetic capacity early in the summer of 2010, but largely regained photosynthetic competence by the end of the growing season. These results indicate that even short-term heat waves can have severe impacts in northern forests, and suggest a particular vulnerability to high temperatures during the spring period of leaf expansion in temperate deciduous forests. PMID:24038752
Class of variational singlet wave functions for the Hubbard model away from half filling
Anderson, P.W. ); Shastry, B.S. ); Hristopulos, D. )
1989-11-01
We present a class of variational wave functions for strong-coupling Heisenberg Hubbard models. These are written in the form of three factors---a pair of determinants and a Jastrow function---and are made out of orbitals, {ital a} {ital la} Hartree-Fock theory, which solve a fictitious one-body problem. The wave functions respect various constraints known from general principles and appear to be potentially useful in understanding the possible behavior of the models in quantitative terms.
Addendum to 'Time-dependent variational principle with constraints for parametrized wave functions'
Ohta, Katsuhisa
2006-04-15
The sensitivity analysis for the time-dependent variational principle (TDVP) with constraints for parametrized wave functions [K. Ohta, Phys. Rev. A 70, 022503 (2004)] is investigated to assess the geodesic deviation caused by external parameters. The constraints for the sensitivity functions, inherited from the TDVP, are dealt with their consistency conditions. As an example of the sensitivity analysis, the geodesic deviation in the neighborhood of stationary states is investigated for general wave functions.
Coherent molecular transistor: Control through variation of the gate wave function
Ernzerhof, Matthias
2014-03-21
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.
Impact of complex blast waves on the human head: a computational study.
Tan, Long Bin; Chew, Fatt Siong; Tse, Kwong Ming; Chye Tan, Vincent Beng; Lee, Heow Pueh
2014-12-01
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. PMID:25132676
Sketches of a hammer-impact, spiked-base, shear-wave source
Hasbrouck, W.P.
1983-01-01
Generation of shear waves in shallow seismic investigations (those to depths usually less than 100 m) can be accomplished by horizontally striking with a hammer either the end of a wood plank or metal structure embedded at the ground surface. The dimensioned sketches of this report are of a steel, hammer-impact, spiked-base, shear-wave source. It has been used on outcrops and in a desert environment and for conducting experiments on the effect of rotating source direction.
Planetary wave reflection and its impact on tropospheric cold weather over Asia during January 2008
NASA Astrophysics Data System (ADS)
Nath, Debashis; Chen, Wen; Wang, Lin; Ma, Yin
2014-07-01
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.
Propagation of ultrasonic Love waves in nonhomogeneous elastic functionally graded materials.
Kiełczyński, P; Szalewski, M; Balcerzak, A; Wieja, K
2016-02-01
This paper presents a theoretical study of the propagation behavior of ultrasonic Love waves in nonhomogeneous functionally graded elastic materials, which is a vital problem in the mechanics of solids. The elastic properties (shear modulus) of a semi-infinite elastic half-space vary monotonically with the depth (distance from the surface of the material). The Direct Sturm-Liouville Problem that describes the propagation of Love waves in nonhomogeneous elastic functionally graded materials is formulated and solved by using two methods: i.e., (1) Finite Difference Method, and (2) Haskell-Thompson Transfer Matrix Method. The dispersion curves of phase and group velocity of surface Love waves in inhomogeneous elastic graded materials are evaluated. The integral formula for the group velocity of Love waves in nonhomogeneous elastic graded materials has been established. The effect of elastic non-homogeneities on the dispersion curves of Love waves is discussed. Two Love wave waveguide structures are analyzed: (1) a nonhomogeneous elastic surface layer deposited on a homogeneous elastic substrate, and (2) a semi-infinite nonhomogeneous elastic half-space. Obtained in this work, the phase and group velocity dispersion curves of Love waves propagating in the considered nonhomogeneous elastic waveguides have not previously been reported in the scientific literature. The results of this paper may give a deeper insight into the nature of Love waves propagation in elastic nonhomogeneous functionally graded materials, and can provide theoretical guidance for the design and optimization of Love wave based devices. PMID:26482393
NASA Astrophysics Data System (ADS)
Shchadilova, Yulia E.; Grusdt, Fabian; Rubtsov, Alexey N.; Demler, Eugene
2016-04-01
We propose a class of variational Gaussian wave functions to describe Fröhlich polarons at finite momenta. Our wave functions give polaron energies that are in excellent agreement with the existing Monte Carlo results for a broad range of interactions. We calculate the effective mass of polarons and find smooth crossover between weak- and intermediate-coupling strength. Effective masses that we obtain are considerably larger than those predicted by the mean-field method. A prediction based on our variational wave functions is a special pattern of correlations between host atoms that can be measured in time-of-flight experiments.
Natural environmental impacts on teleost immune function.
Makrinos, Daniel L; Bowden, Timothy J
2016-06-01
The environment in which teleosts exist can experience considerable change. Short-term changes can occur in relation to tidal movements or adverse weather events. Long-term changes can be caused by anthropogenic impacts such as climate change, which can result in changes to temperature, acidity, salinity and oxygen capacity of aquatic environments. These changes can have important impacts on the physiology of an animal, including its immune system. This can have consequences on the well-being of the animal and its ability to protect against pathogens. This review will look at recent investigations of these types of environmental change on the immune response in teleosts. PMID:26973022
Data synthesis and display programs for wave distribution function analysis
NASA Technical Reports Server (NTRS)
Storey, L. R. O.; Yeh, K. J.
1992-01-01
At the National Space Science Data Center (NSSDC) software was written to synthesize and display artificial data for use in developing the methodology of wave distribution analysis. The software comprises two separate interactive programs, one for data synthesis and the other for data display.
McKechnie, Scott; Booth, George H.; Cohen, Aron J.; Cole, Jacqueline M.
2015-05-21
The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density functional theory (DFT) and wave function methods: Hartree-Fock theory, second-order Møller-Plesset perturbation theory, and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy difference calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared.
McKechnie, Scott; Booth, George H; Cohen, Aron J; Cole, Jacqueline M
2015-05-21
The best practice in computational methods for determining vertical ionization energies (VIEs) is assessed, via reference to experimentally determined VIEs that are corroborated by highly accurate coupled-cluster calculations. These reference values are used to benchmark the performance of density functional theory (DFT) and wave function methods: Hartree-Fock theory, second-order Møller-Plesset perturbation theory, and Electron Propagator Theory (EPT). The core test set consists of 147 small molecules. An extended set of six larger molecules, from benzene to hexacene, is also considered to investigate the dependence of the results on molecule size. The closest agreement with experiment is found for ionization energies obtained from total energy difference calculations. In particular, DFT calculations using exchange-correlation functionals with either a large amount of exact exchange or long-range correction perform best. The results from these functionals are also the least sensitive to an increase in molecule size. In general, ionization energies calculated directly from the orbital energies of the neutral species are less accurate and more sensitive to an increase in molecule size. For the single-calculation approach, the EPT calculations are in closest agreement for both sets of molecules. For the orbital energies from DFT functionals, only those with long-range correction give quantitative agreement with dramatic failing for all other functionals considered. The results offer a practical hierarchy of approximations for the calculation of vertical ionization energies. In addition, the experimental and computational reference values can be used as a standardized set of benchmarks, against which other approximate methods can be compared. PMID:26001454
Degenerate RS perturbation theory. [Rayleigh-Schroedinger energies and wave functions
NASA Technical Reports Server (NTRS)
Hirschfelder, J. O.; Certain, P. R.
1974-01-01
A concise, systematic procedure is given for determining the Rayleigh-Schroedinger energies and wave functions of degenerate states to arbitrarily high orders even when the degeneracies of the various states are resolved in arbitrary orders. The procedure is expressed in terms of an iterative cycle in which the energy through the (2n + 1)-th order is expressed in terms of the partially determined wave function through the n-th order. Both a direct and an operator derivation are given. The two approaches are equivalent and can be transcribed into each other. The direct approach deals with the wave functions (without the use of formal operators) and has the advantage that it resembles the usual treatment of nondegenerate perturbations and maintains close contact with the basic physics. In the operator approach, the wave functions are expressed in terms of infinite-order operators which are determined by the successive resolution of the space of the zeroth-order functions.
Non-Gaussian wave functionals in Coulomb gauge Yang-Mills theory
Campagnari, Davide R.; Reinhardt, Hugo
2010-11-15
A general method to treat non-Gaussian vacuum wave functionals in the Hamiltonian formulation of a quantum field theory is presented. By means of Dyson-Schwinger techniques, the static Green functions are expressed in terms of the kernels arising in the Taylor expansion of the exponent of the vacuum wave functional. These kernels are then determined by minimizing the vacuum expectation value of the Hamiltonian. The method is applied to Yang-Mills theory in Coulomb gauge, using a vacuum wave functional whose exponent contains up to quartic terms in the gauge field. An estimate of the cubic and quartic interaction kernels is given using as input the gluon and ghost propagators found with a Gaussian wave functional.
Impact of rotation on stochastic excitation of gravity and gravito-inertial waves in stars
NASA Astrophysics Data System (ADS)
Mathis, S.; Neiner, C.; Tran Minh, N.
2014-05-01
Context. Gravity waves (or their signatures) are detected in stars thanks to helio- and asteroseismology, and they may play an important role in the evolution of stellar angular momentum. Moreover, a previous observational study of the CoRoT target HD 51452 demonstrated the potential strong impact of rotation on the stochastic excitation of gravito-inertial waves in stellar interiors. Aims: Our goal is to explore and unravel the action of rotation on the stochastic excitation of gravity and gravito-inertial waves in stars. Methods: The dynamics of gravito-inertial waves in stellar interiors in both radiation and in convection zones is described with a local non-traditional f-plane model. The coupling of these waves with convective turbulent flows, which leads to their stochastic excitation, is studied in this framework. Results: First, we find that in the super-inertial regime in which the wave frequency is twice as high as the rotation frequency (σ > 2Ω), the evanescence of gravito-inertial waves in convective regions decreases with decreasing wave frequency. Next, in the sub-inertial regime (σ < 2Ω), gravito-inertial waves become purely propagative inertial waves in convection zones. Simultaneously, turbulence in convective regions is modified by rotation. Indeed, the turbulent energy cascade towards small scales is slowed down, and in the case of rapid rotation, strongly anisotropic turbulent flows are obtained that can be understood as complex non-linear triadic interactions of propagative inertial waves. These different behaviours, due to the action of the Coriolis acceleration, strongly modify the wave coupling with turbulent flows. On one hand, turbulence weakly influenced by rotation is coupled with evanescent gravito-inertial waves. On the other hand, rapidly rotating turbulence is intrinsically and strongly coupled with sub-inertial waves. Finally, to study these mechanisms, the traditional approximation cannot be assumed because it does not properly treat the coupling between gravity and inertial waves in the sub-inertial regime. Conclusions: Our results demonstrate the action of rotation on stochastic excitation of gravity waves thanks to the Coriolis acceleration, which modifies their dynamics in rapidly rotating stars and turbulent flows. As the ratio 2Ω/σ increases, the couplings and thus the amplitude of stochastic gravity waves are amplified.
Application of the SPH method to solitary wave impact on an offshore platform
NASA Astrophysics Data System (ADS)
Pan, K.; IJzermans, R. H. A.; Jones, B. D.; Thyagarajan, A.; van Beest, B. W. H.; Williams, J. R.
2015-09-01
This paper investigates the interaction between large waves and floating offshore structures. Here, the fluid-structure interaction is considered using the weakly compressible smoothed particle hydrodynamics (SPH) method. To ensure the applicability of this method, we validate its prediction for fluid forces and rigid-body motion against two sets of experimental data. These are impact due to dam break, and wave induced motion of a floating cube. For the dam break problem, the SPH method is used to predict impact forces on a rectangular column located downstream. In the second case of a floating cube, the SPH method simulates the motion of a buoyant cube under the action of induced waves, where a wall placed upstream of the cube is displaced sinusoidally to induce waves. In both cases, the SPH framework implemented is able to accurately reproduce the experimental results. Following validation, we apply this framework to simulation of a toy model of a tension-leg platform upon impact of a large solitary wave. This analysis shows that the platform may be pulled into the water by stretched tension legs, where the extension of the tension legs also governs the rotational behavior of the platform. The result also indicates that a tension-leg platform is very unlikely to topple over during the arrival of an extreme wave.
Application of the SPH method to solitary wave impact on an offshore platform
NASA Astrophysics Data System (ADS)
Pan, K.; IJzermans, R. H. A.; Jones, B. D.; Thyagarajan, A.; van Beest, B. W. H.; Williams, J. R.
2016-04-01
This paper investigates the interaction between large waves and floating offshore structures. Here, the fluid-structure interaction is considered using the weakly compressible smoothed particle hydrodynamics (SPH) method. To ensure the applicability of this method, we validate its prediction for fluid forces and rigid-body motion against two sets of experimental data. These are impact due to dam break, and wave induced motion of a floating cube. For the dam break problem, the SPH method is used to predict impact forces on a rectangular column located downstream. In the second case of a floating cube, the SPH method simulates the motion of a buoyant cube under the action of induced waves, where a wall placed upstream of the cube is displaced sinusoidally to induce waves. In both cases, the SPH framework implemented is able to accurately reproduce the experimental results. Following validation, we apply this framework to simulation of a toy model of a tension-leg platform upon impact of a large solitary wave. This analysis shows that the platform may be pulled into the water by stretched tension legs, where the extension of the tension legs also governs the rotational behavior of the platform. The result also indicates that a tension-leg platform is very unlikely to topple over during the arrival of an extreme wave.
Waves Generated by Asteroid Impacts and Their Hazard Consequences on The Shorelines
NASA Astrophysics Data System (ADS)
Ezzedine, S. M.; Miller, P. L.; Dearborn, D. S.
2014-12-01
We have performed numerical simulations of a hypothetical asteroid impact onto the ocean in support of an emergency preparedness, planning, and management exercise. We addressed the scenario from asteroid entry; to ocean impact (splash rim); to wave generation, propagation, and interaction with the shoreline. For the analysis we used GEODYN, a hydrocode, to simulate the impact and generate the source wave for the large-scale shallow water wave program, SWWP. Using state-of-the-art, high-performance computing codes we simulated three impact areas — two are located on the West Coast near Los Angeles's shoreline and the San Francisco Bay, respectively, and the third is located in the Gulf of Mexico, with a possible impact location between Texas and Florida. On account of uncertainty in the exact impact location within the asteroid risk corridor, we examined multiple possibilities for impact points within each area. Uncertainty in the asteroid impact location was then convolved and represented as uncertainty in the shoreline flooding zones. 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.
Ocean wave-radar modulation transfer functions from the West Coast experiment
NASA Technical Reports Server (NTRS)
Wright, J. W.; Plant, W. J.; Keller, W. C.; Jones, W. L.
1980-01-01
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 cross spectrum of the line-of-sight orbital speed and backscattered microwave power to the autospectrum of the line-of-sight orbital speed) were measured at 9.375 and 1.5 GHz (Bragg wavelengths of 2.3 and 13 cm) for winds up to 10 m/s and ocean wave periods from 2-18 s. The measurements were compared with the relaxation-time model; the principal result is that a source of modulation other than straining by the horizontal component of orbital speed, possibly the wave-induced airflow, is responsible for most of the modulation by waves of typical ocean wave period (10 s). The modulations are large; for unit coherence, spectra of radar images of deep-water waves should be proportional to the quotient of the slope spectra of the ocean waves by the ocean wave frequency.
NASA Astrophysics Data System (ADS)
Aoki, Sinya; Ishii, Noriyoshi; Doi, Takumi; Ikeda, Yoichi; Inoue, Takashi
2013-07-01
We derive asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave function at large space separations for systems with more than two particles in quantum field theories. To deal with n particles in the center-of-mass frame coherently, we introduce the Jacobi coordinates of n particles and then combine their 3(n-1) coordinates into the one spherical coordinate in D=3(n-1) dimensions. We parametrize the on-shell T matrix for n scalar particles at low energy using the unitarity constraint of the S matrix. We then express asymptotic behaviors of the NBS wave function for n particles at low energy in terms of parameters of the T matrix and show that the NBS wave function carries information of the T matrix such as phase shifts and mixing angles of the n-particle system in its own asymptotic behavior, so that the NBS wave function can be considered as the scattering wave of n particles in quantum mechanics. This property is one of the essential ingredients of the HAL QCD scheme to define “potential” from the NBS wave function in quantum field theories such as QCD. Our results, together with an extension to systems with spin 1/2 particles, justify the HAL QCD’s definition of potentials for three or more nucleons (or baryons) in terms of the NBS wave functions.
The impact of sea surface currents in wave power potential modeling
NASA Astrophysics Data System (ADS)
Zodiatis, George; Galanis, George; Kallos, George; Nikolaidis, Andreas; Kalogeri, Christina; Liakatas, Aristotelis; Stylianou, Stavros
2015-11-01
The impact of sea surface currents to the estimation and modeling of wave energy potential over an area of increased economic interest, the Eastern Mediterranean Sea, is investigated in this work. High-resolution atmospheric, wave, and circulation models, the latter downscaled from the regional Mediterranean Forecasting System (MFS) of the Copernicus marine service (former MyOcean regional MFS system), are utilized towards this goal. The modeled data are analyzed by means of a variety of statistical tools measuring the potential changes not only in the main wave characteristics, but also in the general distribution of the wave energy and the wave parameters that mainly affect it, when using sea surface currents as a forcing to the wave models. The obtained results prove that the impact of the sea surface currents is quite significant in wave energy-related modeling, as well as temporally and spatially dependent. These facts are revealing the necessity of the utilization of the sea surface currents characteristics in renewable energy studies in conjunction with their meteo-ocean forecasting counterparts.
Decreased impacts of the 2003 heat waves on mortality in the Czech Republic: an improved response?
NASA Astrophysics Data System (ADS)
Kyselý, Jan; Kříž, Bohumír
2008-11-01
The paper examines impacts on mortality of heat waves in 2003, the hottest summer on record in the Czech Republic, and compares them with previous similar events. While most summer heat waves over the period since 1986 were associated with significantly elevated mortality, this was not the case for three out of the four heat waves in 2003. The relatively weak mortality response was particularly noteworthy for the most severe heat wave which occurred in the first 10 days of August 2003 and resulted in enormous excess mortality in some western European countries. A mortality displacement effect and short-term adaptation to heat contributed to the reduced mortality impacts of the heat waves that followed after previous relatively warm periods. However, the decreased mortality response of the 2003 heat waves compared to previous heat waves in the 1990s is also likely to have arisen from positive health-care and other socio-economic changes in the post-communist central European region over the past decade, as well as a better public awareness of heat-related risks due to enhanced media coverage and regular biometeorological forecast and warnings.
Wave-Induced Pressure Under an Internal Solitary Wave and Its Impact at the Bed
NASA Astrophysics Data System (ADS)
Rivera, Gustavo; Diamesis, Peter; Jenkins, James; Berzi, Diego
2015-11-01
The bottom boundary layer (BBL) under a mode-1 internal solitary wave (ISW) of depression propagating against an oncoming model barotropic current is examined using 2-D direct numerical simulation based on a spectral multidomain penalty method model. Particular emphasis is placed on the diffusion into the bed of the pressure field driven by the wake and any near-bed instabilities produced under specific conditions. To this end, a spectral nodal Galerkin approach is used for solving the diffusion equation for the wave-induced pressure. At sufficiently high ISW amplitude, the BBL undergoes a global instability which produces intermittent vortex shedding from within the separation bubble in the lee of the wave. The interplay between the bottom shear stress field and pressure perturbations during vortex ejection events and the subsequent evolution of the vortices is examined. The potential for bed failure upon the passage of the ISW trough and implications for resuspension of bottom particulate matter are both discussed in the context of specific sediment transport models.
Assessment of the Impact of the 2003 and 2006 Heat Waves on Cattle Mortality in France
Morignat, Eric; Perrin, Jean-Baptiste; Gay, Emilie; Vinard, Jean-Luc; Calavas, Didier; Hénaux, Viviane
2014-01-01
Objectives While several studies have highlighted and quantified human mortality during the major heat waves that struck Western Europe in 2003 and 2006, the impact on farm animals has been overlooked. The aim of this study was to assess the effect of these two events on cattle mortality in France, one of the most severely impacted countries. Methods Poisson regressions were used to model the national baseline for cattle mortality between 2004 and 2005 and predict the weekly number of expected deaths in 2003 and 2006 for the whole cattle population and by subpopulation based on age and type of production. Observed and estimated values were compared to identify and quantify excess mortality. The same approach was used at a departmental scale (a French department being an administrative and territorial division) to assess the spatio-temporal evolution of the mortality pattern. Results Overall, the models estimated relative excess mortality of 24% [95% confidence interval: 22–25%] for the two-week heat wave of 2003, and 12% [11–14%] for the three-week heat wave of 2006. In 2003, most cattle subpopulations were impacted during the heat wave and some in the following weeks too. In 2006, cattle subpopulations were impacted for a limited time only, with no excess mortality at the beginning or after the heat wave. No marked differences in cattle mortality were found among the different subpopulations by age and type of production. The implications of these results for risk prevention are discussed. PMID:24667835
NASA Astrophysics Data System (ADS)
Yang, S. Y.; Liu, X.; Cao, D. F.; Mei, H.; Lei, Z. T.; Liu, L. S.
2013-03-01
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.
NASA Astrophysics Data System (ADS)
Porritt, R. W.; Allen, R. M.; Pollitz, F. F.; Hung, S.; Obrebski, M. J.
2011-12-01
The Earthscope USArray is providing an unprecedented dataset for seismic imaging. Many studies have generated models in terms of velocity or impedance contrast, but only a few are starting to integrate observations in a joint framework. The most common joint method inverts receiver function delay times with surface wave dispersion curves to image the crust and mantle lithosphere. Advances have also been made by jointly inverting surface wave dispersion observations with body wave relative travel times to image the upper mantle. These joint methods are producing clearer images and are fitting more observations than single dataset methods, however they do have their limitations. The surface wave and receiver function models are limited to the lithosphere while the body wave and surface wave models are inherently smooth which blurs the layered earth structure. By jointly inverting all three datasets we are able to image structure from the surface through the mantle transition zone under the Transportable Array footprint through July 2011. The stable North American craton is imaged at the eastern edge of the model as a thick high velocity body. The western portion of the model is largely slow through the thin lithosphere and upper asthenosphere relative to the craton. Within the asthenosphere, a 'slab graveyard' is imaged where broken fragments of Farallon slab reside. The Yellowstone anomaly rises amongst these slab pieces from the lower mantle to near the surface exerting control over local seismicity and topography. The Colorado Plateau shows signs of weakening of the lithospheric root resulting in removal by dripping. As a whole, the DNA11 model shows the mantle is far from a simple homogeneous medium.
Impact of Parameterized Lee Wave Drag on the Energy Budget of an Eddying Global Ocean Model
NASA Astrophysics Data System (ADS)
Trossman, D. S.; Arbic, B. K.; Garner, S.; Goff, J. A.; Jayne, S. R.; Metzger, E.; Wallcraft, A.
2012-12-01
We examine the impact of a lee wave drag parameterization on an eddying global ocean model. The wave drag parameterization represents the the momentum transfer associated with the generation of lee waves arising from geostrophic flow impinging upon rough topography. It is included in the online model, thus ensuring that abyssal currents and stratification in the simulation are affected by the presence of the wave drag. The model utilized here is the nominally 1/12th degree Hybrid Coordinate Ocean Model (HYCOM) forced by winds and air-sea buoyancy fluxes. An energy budget including the parameterized wave drag, quadratic bottom boundary layer drag, vertical eddy viscosity, and horizontal eddy viscosity is diagnosed during the model runs and compared with the wind power input and buoyancy fluxes. Wave drag and vertical viscosity are the largest of the mechanical energy dissipation rate terms, each more than half of a terawatt when globally integrated. The sum of all four dissipative terms approximately balances the rate of energy put by the winds and buoyancy fluxes into the ocean. An ad hoc global enhancement of the bottom drag at each grid point by a constant factor cannot serve as a perfect substitute for wave drag, particularly where there is little wave drag. Eddy length scales at the surface, sea surface height variance, surface kinetic energy, and positions of intensified jets in the model are compared with those inferred from altimetric observations. Vertical profiles of kinetic energy from the model are compared with mooring observations to investigate whether the model is improved when wave drag is inserted.; The drag and viscosity terms in our energy budget [log_10(W m^-2)]: (a) quadratic bottom boundary layer drag, (b) parameterized internal lee wave drag, (c) vertical viscosity, and (d) "horizontal" viscosity. Shown is an average of inline estimates over one year of the spin-up phase with wave drag.
[Impact of thyroid function on fertility].
Gronier, H; Sonigo, C; Jacquesson, L
2015-03-01
Until recently, anovulation or recurrent miscarriages were the only situations for screening a thyroid dysfunction in an infertile patient. Recent U.S. guidelines published in 2011 identify infertile women as being at risk for thyroid dysfunction. This paper proposes, on the occasion of the new recommendations, a review of the literature data on the known impact of thyroid dysfunction on fertility, on the first trimester of pregnancy and on the way to treat them. PMID:25724447
Wave function continuity and the diagonal Born-Oppenheimer correction at conical intersections
NASA Astrophysics Data System (ADS)
Meek, Garrett A.; Levine, Benjamin G.
2016-05-01
We demonstrate that though exact in principle, the expansion of the total molecular wave function as a sum over adiabatic Born-Oppenheimer (BO) vibronic states makes inclusion of the second-derivative nonadiabatic energy term near conical intersections practically problematic. In order to construct a well-behaved molecular wave function that has density at a conical intersection, the individual BO vibronic states in the summation must be discontinuous. When the second-derivative nonadiabatic terms are added to the Hamiltonian, singularities in the diagonal BO corrections (DBOCs) of the individual BO states arise from these discontinuities. In contrast to the well-known singularities in the first-derivative couplings at conical intersections, these singularities are non-integrable, resulting in undefined DBOC matrix elements. Though these singularities suggest that the exact molecular wave function may not have density at the conical intersection point, there is no physical basis for this constraint. Instead, the singularities are artifacts of the chosen basis of discontinuous functions. We also demonstrate that continuity of the total molecular wave function does not require continuity of the individual adiabatic nuclear wave functions. We classify nonadiabatic molecular dynamics methods according to the constraints placed on wave function continuity and analyze their formal properties. Based on our analysis, it is recommended that the DBOC be neglected when employing mixed quantum-classical methods and certain approximate quantum dynamical methods in the adiabatic representation.
Wave function continuity and the diagonal Born-Oppenheimer correction at conical intersections.
Meek, Garrett A; Levine, Benjamin G
2016-05-14
We demonstrate that though exact in principle, the expansion of the total molecular wave function as a sum over adiabatic Born-Oppenheimer (BO) vibronic states makes inclusion of the second-derivative nonadiabatic energy term near conical intersections practically problematic. In order to construct a well-behaved molecular wave function that has density at a conical intersection, the individual BO vibronic states in the summation must be discontinuous. When the second-derivative nonadiabatic terms are added to the Hamiltonian, singularities in the diagonal BO corrections (DBOCs) of the individual BO states arise from these discontinuities. In contrast to the well-known singularities in the first-derivative couplings at conical intersections, these singularities are non-integrable, resulting in undefined DBOC matrix elements. Though these singularities suggest that the exact molecular wave function may not have density at the conical intersection point, there is no physical basis for this constraint. Instead, the singularities are artifacts of the chosen basis of discontinuous functions. We also demonstrate that continuity of the total molecular wave function does not require continuity of the individual adiabatic nuclear wave functions. We classify nonadiabatic molecular dynamics methods according to the constraints placed on wave function continuity and analyze their formal properties. Based on our analysis, it is recommended that the DBOC be neglected when employing mixed quantum-classical methods and certain approximate quantum dynamical methods in the adiabatic representation. PMID:27179473
NASA Astrophysics Data System (ADS)
Matsue, Kazuma; Arakawa, Masahiko; Yasui, Minami; Matsumoto, Rie; Tsujido, Sayaka; Takano, Shota; Hasegawa, Sunao
2015-08-01
Introduction: Recent spacecraft surveys clarified that asteroid surfaces were covered with regolith made of boulders and pebbles such as that found on the asteroid Itokawa. It was also found that surface morphologies of asteroids formed on the regolith layer were modified. For example, the high-resolution images of the asteroid Eros revealed the evidence of the downslope movement of the regolith layer, then it could cause the degradation and the erasure of small impact crater. One possible process to explain these observations is the regolith layer collapse caused by seismic vibration after projectile impacts. The impact-induced seismic wave might be an important physical process affecting the morphology change of regolith layer on asteroid surfaces. Therefore, it is significant for us to know the relationship between the impact energy and the impact-induced seismic wave. So in this study, we carried out impact cratering experiments in order to observe the seismic wave propagating through the target far from the impact crater.Experimental method: Impact cratering experiments were conducted by using a single stage vertical gas gun set at Kobe Univ and a two-stage vertical gas gun set at ISAS. We used quartz sands with the particle diameter of 500μm, and the bulk density of 1.48g/cm3. The projectile was a ball made of polycarbonate with the diameter of 4.75mm and aluminum, titan, zirconia, stainless steel, cupper, tungsten carbide projectile with the diameter of 2mm. These projectiles were launched at the impact velocity from 0.2 to 7km/s. The target was set in a vacuum chamber evacuated below 10 Pa. We measured the seismic wave by using a piezoelectric uniaxial accelerometer.Result: The impact-induced seismic wave was measured to show a large single peak and found to attenuate with the propagation distance. The maximum acceleration of the seismic wave was recognized to have a good relationship with the normalized distance x/R, where x is the propagation distance and R is the crater radius, irrespective of the impact velocities: gmax = 160(x/R)-2.98.
Impact of heat waves on mortality in Croatia
NASA Astrophysics Data System (ADS)
Zaninović, Ksenija; Matzarakis, Andreas
2014-08-01
The aim of this work was to determine the criteria for heat loads associated with an increase in mortality in different climatic regions of Croatia. The relationship between heat stress and mortality was analysed for the period 1983-2008. The input series is excess mortality defined as the deviations of mortality from expected values determined by means of a Gaussian filter of 183 days. The assessment of the thermal environment was performed by means of physiologically equivalent temperature (PET). The curve depicting the relationship between mortality and temperature has a U shape, with increased mortality in both the cold and warm parts of the scale but more pronounced in the warm part. The threshold temperature for increased mortality was determined using a scatter plot and fitting data by means of moving average of mortality; the latter is defined as the temperature at which excess mortality becomes significant. The values are higher in the continental part of Croatia than at the coast due to the refreshing influence of the sea during the day. The same analysis on a monthly basis shows that at the beginning of the warm season increased mortality occurs at a lower temperature compared with later on in the summer, and the difference is up to 15 °C between August and April. The increase in mortality is highest during the first 3-5 days and after that it decreases and falls below the expected value. Long-lasting heat waves present an increased risk, but in very long heat waves the increase in mortality is reduced due to mortality displacement.
Impact Energy of Functionally Graded Steels in Crack Arrester Configuration
NASA Astrophysics Data System (ADS)
Nazari, A.; Aghazadeh Mohandesi, J.
2010-10-01
Charpy impact energy of functionally graded steels produced by electroslag remelting composed of graded ferrite and austenite layers together with bainite or martensite intermediate layer in the form of crack arrester configuration has been investigated. The results obtained in the present study indicate that the notch tip position with respect to bainite or martensite layer significantly affects the impact energy. The closer the notch tip to the tougher layer, the higher the impact energy of the composite due to increment of energy absorbed by plastic deformation zone ahead of the notch and vice versa. Empirical relationships have been determined to correlate the impact energy of functionally graded steels to the morphology of layers.
A Study of Regional Wave Source Time Functions of Central Asian Earthquakes
NASA Astrophysics Data System (ADS)
Xie, J.; Perry, M. R.; Schult, F. R.; Wood, J.
2014-12-01
Despite the extensive use of seismic regional waves in seismic event identification and attenuation tomography, very little is known on how seismic sources radiate energy into these waves. For example, whether regional Lg wave has the same source spectrum as that of the local S has been questioned by Harr et al. and Frenkel et al. three decades ago; many current investigators assume source spectra in Lg, Sn, Pg, Pn and Lg coda waves have either the same or very similar corner frequencies, in contrast to local P and S spectra whose corner frequencies differ. The most complete information on how the finite source ruptures radiate energy into regional waves is contained in the time domain source time functions (STFs). To estimate the STFs of regional waves using the empirical Green's function (EGF) method, we have been substantially modifying a semi-automotive computer procedure to cope with the increasingly diverse and inconsistent naming patterns of new data files from the IRIS DMC. We are applying the modified procedure to many earthquakes in central Asia to study the STFs of various regional waves to see whether they have the same durations and pulse shapes, and how frequently source directivity occur. When applicable, we also examine the differences between STFs of local P and S waves and those of regional waves. The result of these analyses will be presented at the meeting.
Wave functions of symmetry-protected topological phases from conformal field theories
NASA Astrophysics Data System (ADS)
Scaffidi, Thomas; Ringel, Zohar
2016-03-01
We propose a method for analyzing two-dimensional symmetry-protected topological (SPT) wave functions using a correspondence with conformal field theories (CFTs) and integrable lattice models. This method generalizes the CFT approach for the fractional quantum Hall effect wherein the wave-function amplitude is written as a many-operator correlator in the CFT. Adopting a bottom-up approach, we start from various known microscopic wave functions of SPTs with discrete symmetries and show how the CFT description emerges at large scale, thereby revealing a deep connection between group cocycles and critical, sometimes integrable, models. We show that the CFT describing the bulk wave function is often also the one describing the entanglement spectrum, but not always. Using a plasma analogy, we also prove the existence of hidden quasi-long-range order for a large class of SPTs. Finally, we show how response to symmetry fluxes is easily described in terms of the CFT.
Continuity Conditions on Schrodinger Wave Functions at Discontinuities of the Potential.
ERIC Educational Resources Information Center
Branson, David
1979-01-01
Several standard arguments which attempt to show that the wave function and its derivative must be continuous across jump discontinuities of the potential are reviewed and their defects discussed. (Author/HM)
Impact of Stone Removal on Renal Function: A Review
Wood, Kyle; Keys, Tristan; Mufarrij, Patrick; Assimos, Dean G
2011-01-01
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
NASA Astrophysics Data System (ADS)
Hu, Dingzhu; Tian, Wenshou; Xie, Fei; Wang, Chunxiao; Zhang, Jiankai
2015-08-01
This paper uses a state-of-the-art general circulation model to study the impacts of the stratospheric ozone depletion from 1980 to 2000 and the expected partial ozone recovery from 2000 to 2020 on the propagation of planetary waves in December, January, and February. In the Southern Hemisphere (SH), the stratospheric ozone depletion leads to a cooler and stronger Antarctic stratosphere, while the stratospheric ozone recovery has the opposite effects. In the Northern Hemisphere (NH), the impacts of the stratospheric ozone depletion on polar stratospheric temperature are not opposite to that of the stratospheric ozone recovery; i.e., the stratospheric ozone depletion causes a weak cooling and the stratospheric ozone recovery causes a statistically significant cooling. The stratospheric ozone depletion leads to a weakening of the Arctic polar vortex, while the stratospheric ozone recovery leads to a strengthening of the Arctic polar vortex. The cooling of the Arctic polar vortex is found to be dynamically induced via modulating the planetary wave activity by stratospheric ozone increases. Particularly interesting is that stratospheric ozone changes have opposite effects on the stationary and transient wave fluxes in the NH stratosphere. The analysis of the wave refractive index and Eliassen-Palm flux in the NH indicates (1) that the wave refraction in the stratosphere cannot fully explain wave flux changes in the Arctic stratosphere and (2) that stratospheric ozone changes can cause changes in wave propagation in the northern midlatitude troposphere which in turn affect wave fluxes in the NH stratosphere. In the SH, the radiative cooling (warming) caused by stratospheric ozone depletion (recovery) produces a larger (smaller) meridional temperature gradient in the midlatitude upper troposphere, accompanied by larger (smaller) zonal wind vertical shear and larger (smaller) vertical gradients of buoyancy frequency. Hence, there are more (fewer) transient waves propagating into the stratosphere. The dynamical warming (cooling) caused by stratospheric ozone decreases (increases) partly offsets their radiative cooling (warming).
Multifractal Wave Functions of a System with a Monofractal Energy Spectrum
NASA Astrophysics Data System (ADS)
Tashima, Masayuki; Tasaki, Shuichi
2011-07-01
We show the appearance of multifractal wave functions on a one-dimensional quasiperiodic system that has a monofractal energy spectrum. Using the Mantica technique, we construct the model as an inverse problem from the energy spectrum of a pure Cantor set. The particle--hole symmetry and a relationship between the critical state and the information dimension are proved. This relationship is applied to the finite-size multifractal analysis of the wave functions.
Miyake, Hirokazu; Siviloglou, Georgios A; Puentes, Graciana; Pritchard, David E; Ketterle, Wolfgang; Weld, David M
2011-10-21
We have observed Bragg scattering of photons from quantum degenerate ^{87}Rb atoms in a three-dimensional optical lattice. Bragg scattered light directly probes the microscopic crystal structure and atomic wave function whose position and momentum width is Heisenberg limited. The spatial coherence of the wave function leads to revivals in the Bragg scattered light due to the atomic Talbot effect. The decay of revivals across the superfluid to Mott insulator transition indicates the loss of superfluid coherence. PMID:22107532
Structure of the channeling electrons wave functions under dynamical chaos conditions
NASA Astrophysics Data System (ADS)
Shul'ga, N. F.; Syshchenko, V. V.; Tarnovsky, A. I.; Isupov, A. Yu.
2016-03-01
The stationary wave functions of fast electrons axially channeling in the silicon crystal near [1 1 0] direction have been found numerically for integrable and non-integrable cases, for which the classical motion is regular and chaotic, respectively. The nodal structure of the wave functions in the quasi-classical region, where the energy levels density is high, is agreed with quantum chaos theory predictions.
Failure Wave in DEDF and Soda-Lime Glass During Rod Impact
NASA Astrophysics Data System (ADS)
Orphal, Dennis; Behner, Thilo; Anderson, Charles; Templeton, Douglas
2005-07-01
Investigations of glass by planar, and classical and symmetric Taylor impact experiments reveal that failure wave velocity U/F depends on impact velocity, geometry, and the type of glass. U/F typically increases with impact velocity to between ˜ 1.4 C/S and C/L (shear and longitudinal wave velocities, respectively). This paper reports the results of direct high-speed photographic measurements of the failure wave for gold rod impact from 1.2 and 2.0 km/s on DEDF glass (C/S = 2.0, C/L =3.5 km/s). The average rod penetration velocity, u, was measured using flash X-rays. Gold rods eliminated penetrator strength effects. U/F for gold rod impact on DEDF is ˜ 1.0-1.2 km/s, which is considerably less than C/S. The increase of u with impact velocity is greater than that of U/F. These results are confirmed by soda-lime glass impact on a gold rod at an impact velocity of 1300 m/s. Similar results are found in``edge-on-impact'' tests; U/F values of 1.4 km/s and 2.4-2.6 km/s in soda-lime glass are reported for W-alloy rod impact, considerably less than C/S (3.2 km/s) [1,2]. [1] Bless, et. al.(1990) AIP Proc. Shock Comp. Cond. Matter---1989, pp. 939-942 (1990) [2] E. L. Zilberbrand, et. al. (1999) Int. J. Impact Engng., 23, 995-1001 (1999).
Zhang, Y. S.; Cai, F.; Xu, W. M.
2011-09-28
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.
NASA Astrophysics Data System (ADS)
Francisco, E.; Pendás, A. Martín; Blanco, M. A.
2008-04-01
Given an N-electron molecule and an exhaustive partition of the real space ( R) into m arbitrary regions Ω,Ω,…,Ω ( ⋃i=1mΩ=R), the edf program computes all the probabilities P(n,n,…,n) of having exactly n electrons in Ω, n electrons in Ω,…, and n electrons ( n+n+⋯+n=N) in Ω. Each Ω 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 Ω. 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 α and β 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 Ω, n electrons to Ω,…, and n electrons to Ω,{n} being integers. Solution method: Let us assume that the N-electron molecular wave function, Ψ(1,N), is a linear combination of M Slater determinants, Ψ(1,N)=∑rMCψ(1,N). Calling SΩrs the overlap matrix over the 3D region Ω between the (real) molecular spin-orbitals (MSO) in ψ(χ1r,…χNr) and the MSOs in ψ,(χ1s,…,χNs), edf finds all the P({n})'s by solving the linear system ∑{n}{∏kmtkn}P({n})=∑r,sMCCdet[∑kmtSΩrs], 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.
Li, X. P.; Xia, Q.; Qu, D.; Wu, T. C.; Yang, D. G.; Hao, W. D.; Jiang, X.; Li, X. M.
2014-01-01
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
Pineal Function: Impact of Microarray Analysis
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
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
Van Raemdonck, Mario; Alcoba, Diego R; Poelmans, Ward; De Baerdemacker, Stijn; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Van Neck, Dimitri; Bultinck, Patrick
2015-09-14
A class of polynomial scaling methods that approximate Doubly Occupied Configuration Interaction (DOCI) wave functions and improve the description of dynamic correlation is introduced. The accuracy of the resulting wave functions is analysed by comparing energies and studying the overlap between the newly developed methods and full configuration interaction wave functions, showing that a low energy does not necessarily entail a good approximation of the exact wave function. Due to the dependence of DOCI wave functions on the single-particle basis chosen, several orbital optimisation algorithms are introduced. An energy-based algorithm using the simulated annealing method is used as a benchmark. As a computationally more affordable alternative, a seniority number minimising algorithm is developed and compared to the energy based one revealing that the seniority minimising orbital set performs well. Given a well-chosen orbital basis, it is shown that the newly developed DOCI based wave functions are especially suitable for the computationally efficient description of static correlation and to lesser extent dynamic correlation. PMID:26374017
NASA Astrophysics Data System (ADS)
Van Raemdonck, Mario; Alcoba, Diego R.; Poelmans, Ward; De Baerdemacker, Stijn; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E.; Van Neck, Dimitri; Bultinck, Patrick
2015-09-01
A class of polynomial scaling methods that approximate Doubly Occupied Configuration Interaction (DOCI) wave functions and improve the description of dynamic correlation is introduced. The accuracy of the resulting wave functions is analysed by comparing energies and studying the overlap between the newly developed methods and full configuration interaction wave functions, showing that a low energy does not necessarily entail a good approximation of the exact wave function. Due to the dependence of DOCI wave functions on the single-particle basis chosen, several orbital optimisation algorithms are introduced. An energy-based algorithm using the simulated annealing method is used as a benchmark. As a computationally more affordable alternative, a seniority number minimising algorithm is developed and compared to the energy based one revealing that the seniority minimising orbital set performs well. Given a well-chosen orbital basis, it is shown that the newly developed DOCI based wave functions are especially suitable for the computationally efficient description of static correlation and to lesser extent dynamic correlation.
Study of the impact of truncations on wedge waves by using the laser ultrasound technique.
Jia, Jing; Shen, Zhonghua; Sun, KaiHua
2015-08-20
This research focuses on measuring the impact of truncations on the dispersion characteristics of wedge waves propagating along the wedge tip by using the laser-generated ultrasound. First, the finite element method was used to simulate laser-induced wedge waves and the dispersion curves were obtained by using the 2D Fourier transformation method. Pulsed laser excitation and laser-based wedge wave detection were also utilized to investigate these characteristics experimentally. For the 20° and 60° line wedges, both experimental and numerical results indicated that a nonideal wedge tip had great impact on the wedge waves. The modes of the 20° line wedge with truncations presented anomalous dispersion, low mode closed to high mode in high frequency, and the characteristics of antisymmetric Lamb waves as truncation increased. Meanwhile, the modes of the 60° line wedge with truncations showed the characteristics of antisymmetric Lamb waves, and the A_{1} mode was also observed clearly. The findings of this study can be used to evaluate and detect wedge structure. PMID:26368778
Guided waves for the detection and classification of impact damage in composites
NASA Astrophysics Data System (ADS)
Murat, Bibi Intan Suraya; Khalili, Pouyan; Fromme, Paul
2015-03-01
Carbon fiber laminate composites, consisting of layers of polymer matrix reinforced with high strength carbon fibers, are widely employed for aircraft structures. For aerospace applications they offer a number of advantages including a 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 nondestructive testing of composite panels can be achieved using guided ultrasonic waves propagating along the structure. The guided wave propagation in intact composite plates was measured using a noncontact laser interferometer, quantified, and compared to numerical predictions using full three-dimensional (3D) Finite Element (FE) simulations. Good agreement between experiments and predictions for the wave propagation was found. The guided wave scattering at delaminations was simulated using 3D FE models and the influence of the delamination modelling investigated. Limited influence of the material damping and the delamination shape on the scattering patterns was found, but the modelling of the specimen anisotropy was observed to have a significant influence. The effects of the delamination size and depth on the guided wave scattering were investigated in a systematic parametric study, in order to help building up information for an accurate interpretation of guided wave experiments.
Chen, Y.F.; Lu, T.H.; Su, K.W.; Huang, K.F.
2005-11-01
We investigate the quantum signatures of classical nonlinear resonances by making the analytic connection between the quantum wave functions and the classical periodic orbits for the uncoupled systems. It is found that the highly efficient extension of the localized coherent states within the classical caustics is an intriguing phenomenon in mesoscopic systems with nonlinear resonances. With the theoretical analysis, we experimentally demonstrate that the laser resonator with an intracavity saturable absorber can be employed to visualize the wave patterns analogous to the quantum wave functions associated with Fermi resonance.
Coordinated wave function for the ground state of liquid 4He
NASA Astrophysics Data System (ADS)
Lutsyshyn, Y.
2015-12-01
We present a variational ansatz for the ground state of a strongly correlated Bose system. This ansatz goes beyond the Jastrow-Feenberg functional form and explicitly enforces coordination shells in the structure of the wave function. We apply this ansatz to liquid helium-4 with a simple three-variable parametrization of the pair functions. The optimized wave function is found to give an excellent description of the mid-range correlations in the fluid. We also demonstrate the possibility to use this ansatz to study inhomogeneous systems. The phase separation and free surface emerge naturally in this wave function, even though it is constructed of short-range two-body functions and does not contain one-body terms. Because no explicit description of the surface is necessary, this provides a powerful description tool for cluster states.
A whole-space transform formula of cylindrical wave functions for scattering problems
NASA Astrophysics Data System (ADS)
Yuan, Xiaoming
2014-03-01
The theory of elastic wave scattering is a fundamental concept in the study of elastic dynamics and wave motion, and the wave function expansion technique has been widely used in many subjects. To supply the essential tools for solving wave scattering problems induced by an eccentric source or multi-sources as well as multi-scatters, a whole-space transform formula of cylindrical wave functions is presented and its applicability to some simple cases is demonstrated in this study. The transforms of wave functions in cylindrical coordinates can be classified into two basic types: interior transform and exterior transform, and the existing Graf's addition theorem is only suitable for the former. By performing a new replacement between the two coordinates, the exterior transform formula is first deduced. It is then combined with Graf's addition theorem to establish a whole-space transform formula. By using the whole-space transform formula, the scattering solutions by the sources outside and inside a cylindrical cavity are constructed as examples of its application. The effectiveness and advantages of the whole-space transform formula is illustrated by comparison with the approximate model based on a large cycle method. The whole-space transform formula presented herein can be used to perform the transform between two different cylindrical coordinates in the whole space. In addition, its concept and principle are universal and can be further extended to establish the coordinate transform formula of wave functions in other coordinate systems.
Impact of Acoustic Standing Waves on Structural Responses
NASA Technical Reports Server (NTRS)
Kolaini, Ali R.
2014-01-01
For several decades large reverberant chambers and most recently direct field acoustic testing have been used in the aerospace industry to test larger structures with low surface densities such as solar arrays and reflectors to qualify them and to detect faults in the design and fabrication. It has been reported that in reverberant chamber and direct acoustic testing, standing acoustic modes may strongly couple with the fundamental structural modes of the test hardware (Reference 1). In this paper results from a recent reverberant chamber acoustic test of a composite reflector are discussed. These results provide further convincing evidence of the acoustic standing wave and structural modes coupling phenomenon. The purpose of this paper is to alert test organizations to this phenomenon so that they can account for the potential increase in structural responses and ensure that flight hardware undergoes safe testing. An understanding of the coupling phenomenon may also help minimize the over and/or under testing that could pose un-anticipated structural and flight qualification issues.
Biogeochemical impact of tropical instability waves in the equatorial Pacific
NASA Astrophysics Data System (ADS)
Gorgues, T.; Menkes, C.; Aumont, O.; Vialard, J.; Dandonneau, Y.; Bopp, L.
2005-12-01
Tropical Instability Waves (TIW) have been suggested to fertilize the equatorial Pacific in iron leading to enhanced ecosystem productivity. Using a coupled dynamical-biogeochemical model, we show that contrary to this suggestion, TIWs induce a decrease of iron concentration by 10% at the equator and by about 3% over the Wyrtki box [90W-180, 5N-5S]. Chlorophyll decreases by 10% at the equator and 1% over the Wyrtki box. This leads to a decrease of new production up to 10% at the equator (4% over the Wyrtki box). TIW-induced horizontal advection exports iron-rich equatorial water to the north, but also brings iron-depleted water to the equator leading to a net decrease in iron. Additional iron decrease is caused by TIW-induced iron vertical diffusion. These two mechanisms are partly counter balanced by a decrease of iron biological uptake, driven by lower phytoplankton concentrations, and to a lesser extent by TIW-induced iron vertical advection.
NASA Technical Reports Server (NTRS)
Lim, Young-Kwon
2014-01-01
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.
Cumulative impacts on water-quality functions of wetlands
Hemond, H.F.; Benoit, J.
1988-01-01
Cumulative impacts on the water-quality function of wetlands are impacts whose total effect cannot be predicted from the sum of the effects of individual impacts. The wetland is not a simple filter; it embodies chemical, physical, and biotic processes that can detain, transform, release, or produce a wide variety of substances. Because wetland water-quality functions result from the operation of many individual, distinct, and quite dissimilar mechanisms, it is necessary to consider the nature of each individual process. Given knowledge of the various wetland processes, it is possible to make more-guided judgments about the effects a suite of impacts is likely to have. When considered in this light, many common wetland alterations seem likely to involve cumulative impact. The wetland manager may be guided further by appropriate field measurements at specific sites; such data can aid in predicting cumulative impact or assessing the results of past wetland management.
In situ measurements of impact-induced pressure waves in sandstone targets
NASA Astrophysics Data System (ADS)
Hoerth, Tobias; Schäfer, Frank; Nau, Siegfried; Kuder, Jürgen; Poelchau, Michael H.; Thoma, Klaus; Kenkmann, Thomas
2014-10-01
In 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.
Impact of large-scale atmospheric refractive structures on optical wave propagation
NASA Astrophysics Data System (ADS)
Nunalee, Christopher G.; He, Ping; Basu, Sukanta; Vorontsov, Mikhail A.; Fiorino, Steven T.
2014-10-01
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.
Electron-impact excitation-autoionization of helium in the S-wave limit
Horner, Daniel A.; McCurdy, C. William; Rescigno, Thomas N.
2004-10-01
Excitation of the autoionizing states of helium by electron impact is shown in calculations in the s-wave limit to leave a clear signature in the singly differential cross section for the (e,2e) process. It is suggested that such behavior should be seen generally in (e,2e) experiments on atoms that measure the single differential cross section.
Impact of assimilating altimeter data on wave predictions in the western Iberian coast
NASA Astrophysics Data System (ADS)
Rusu, Liliana; Guedes Soares, C.
2015-12-01
The present work describes the implementation of a methodology based on the optimal interpolation method for assimilating the altimeter data in a regional wave forecasting system. The main objective is to improve the wave predictions in the western Iberian coastal environment. The wave modelling system considered is based on WAM, for the wave generation, and on SWAN for the coastal transformation and delivers daily forecast products. An analysis scheme was first applied to the hindcast runs, when the observations and the simulations were blended within a time window of one day. The objective is to validate the methodology proposed and to evaluate the impact produced by this scheme on the accuracy of the wave predictions. Corrections are applied to the output of the SWAN model, and consequently, the data assimilation scheme is executed independently of the model simulations. As a second step, the data assimilation scheme is applied to operational runs, when the analysis fields are used as a first guess for the next simulations. The procedure considered uses the observations provided by the multi-satellite altimeter data. Both satellite data and in-situ observations are used for the quality assessment. The results show that the assimilation scheme works correctly and all the statistical parameters evaluated have better values in the case of the assimilated significant wave height scalar field. As expected, by increasing the amount of the data assimilated, the accuracy of the wave predictions is enhanced.
What is the impact of electromagnetic waves on epileptic seizures?
Cinar, Nilgun; Sahin, Sevki; Erdinc, Oguz O.
2013-01-01
Background The effects of electromagnetic waves (EMWs) on humans and their relationship with various disorders have been investigated. We aimed to investigate the effects of exposure to different frequencies of EMWs in various durations in a mouse epilepsy model induced by pentylenetetrazole (PTZ). Material/Methods A total of 180 4-week-old male mice weighing 25–30 g were used in this study. Each experimental group consisted of 10 mice. They were exposed to 900, 700, 500, 300, and 100 MHz EMWs for 20 hours, 12 hours and 2 hours. Following electromagnetic radiation exposure, 60 mg/kg of PTZ was injected intraperitoneally to all mice. Each control was also injected with PTZ without any exposure to EMW. The latency of initial seizure and most severe seizure onset were compared with controls. Results The shortest initial seizure latency was noted in the 12-hour group, followed by the 700 MHz. The mean initial seizure latencies in the 2-hour EMW exposed group was significantly shorter compared to that in the 12- and 20-hour groups. There was no significant difference between 12- and 20-hour EMW exposed groups. There was a significant difference between control and 2- and 10-hour EMW exposed groups. No statistically significant differences were noted in mean latencies of the most severe seizure latency, following 20-, 12-, and 2- hour EMW exposed groups and control groups. Conclusions Our findings suggest that acute exposure to EMW may facilitate epileptic seizures, which may be independent of EMW exposure time. This information might be important for patients with epilepsy. Further studies are needed. PMID:23676765
The effects of extracorporeal shock wave therapy on frozen shoulder patients' pain and functions.
Park, Chan; Lee, Sangyong; Yi, Chae-Woo; Lee, Kwansub
2015-12-01
[Purpose] The present study was conducted to examine the effects of extracorporeal shock wave therapy on frozen shoulder patients' pain and functions. [Subjects] In the present study, 30 frozen shoulder patients were divided into two groups: an extracorporeal shock wave therapy group of 15 patients and a conservative physical therapy group of 15 patients. [Methods] Two times per week for six weeks, the extracorporeal shock wave therapy group underwent extracorporeal shock wave therapy, and the conservative physical therapy group underwent general physical therapy. Visual analog scales were used to measure frozen shoulder patients' pain, and patient-specific functional scales were used to evaluate the degree of functional disorders. [Results] In intra-group comparisons, the two groups showed significant decreases in terms of visual analog scales and patient-specific functional scales, although the extracorporeal shock wave therapy group showed significantly lower scores than the conservative physical therapy group. [Conclusion] Extracorporeal shock wave therapy is considered an effective intervention for improving frozen shoulder patients' pain and functions. PMID:26834326
The effects of extracorporeal shock wave therapy on frozen shoulder patients’ pain and functions
Park, Chan; Lee, Sangyong; Yi, Chae-Woo; Lee, Kwansub
2015-01-01
[Purpose] The present study was conducted to examine the effects of extracorporeal shock wave therapy on frozen shoulder patients’ pain and functions. [Subjects] In the present study, 30 frozen shoulder patients were divided into two groups: an extracorporeal shock wave therapy group of 15 patients and a conservative physical therapy group of 15 patients. [Methods] Two times per week for six weeks, the extracorporeal shock wave therapy group underwent extracorporeal shock wave therapy, and the conservative physical therapy group underwent general physical therapy. Visual analog scales were used to measure frozen shoulder patients’ pain, and patient-specific functional scales were used to evaluate the degree of functional disorders. [Results] In intra-group comparisons, the two groups showed significant decreases in terms of visual analog scales and patient-specific functional scales, although the extracorporeal shock wave therapy group showed significantly lower scores than the conservative physical therapy group. [Conclusion] Extracorporeal shock wave therapy is considered an effective intervention for improving frozen shoulder patients’ pain and functions. PMID:26834326
Coulomb wave functions with complex values of the variable and the parameters
NASA Astrophysics Data System (ADS)
Dzieciol, Aleksander; Yngve, Staffan; Fröman, Per Olof
1999-12-01
The motivation for the present paper lies in the fact that the literature concerning the Coulomb wave functions FL(η,ρ) and GL(η,ρ) 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 ρ and the parameters L and η. 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 (ρ→ρe±iπ) and asymptotic formulas on a Riemann surface for the variable ρ. The parameters L and η are allowed to assume complex values.
Scattering of impact wave by a crack in composite plate
NASA Technical Reports Server (NTRS)
Ju, T. H.; Datta, S. K.; Shah, A. H.
1990-01-01
The surface responses due to impact load on an infinite uniaxial graphite/epoxy plate with and without delamination cracks are investigated both in time and frequency domain by using a hybrid method combining the finite element discretization of the near-field with boundary integral representation of the field outside a contour enclosing completely the crack. This combined method leads to a set of linear unsymmetric complex matrix equations which are solved to obtain the response in the frequency domain by biconjugate gradient method. The time domain response is then obtained by using an FFT. In order to capture the time-domain characteristics accurately, high order finite elements have been used. Also, both the six node singular elements and eight node transition elements are used around the crack tips to model the crack-tip singularity. It is shown that from the numerical results for surface responses both depth and length of this crack can be identified.
Completeness of the Coulomb Wave Functions in Quantum Mechanics
ERIC Educational Resources Information Center
Mukunda, N.
1978-01-01
Gives an explicit and elementary proof that the radial energy eigenfunctions for the hydrogen atom in quantum mechanics, bound and scattering states included, form a complete set. The proof uses some properties of the confluent hypergeometric functions and the Cauchy residue theorem from analytic function theory. (Author/GA)
Impact of lightning strikes on hospital functions.
Mortelmans, Luc J M; Van Springel, Gert L J; Van Boxstael, Sam; Herrijgers, Jan; Hoflacks, Stefaan
2009-01-01
Two regional hospitals were struck by lightning during a one-month period. The first hospital, which had 236 beds, suffered a direct strike to the building. This resulted in a direct spread of the power peak and temporary failure of the standard power supply. The principle problems, after restoring standard power supply, were with the fire alarm system and peripheral network connections in the digital radiology systems. No direct impact on the hardware could be found. Restarting the servers resolved all problems. The second hospital, which had 436 beds, had a lightning strike on the premises and mainly experienced problems due to induction. All affected installations had a cable connection from outside in one way or another. The power supplies never were endangered. The main problem was the failure of different communication systems (telephone, radio, intercom, fire alarm system). Also, the electronic entrance control went out. During the days after the lightening strike, multiple software problems became apparent, as well as failures of the network connections controlling the technical support systems. There are very few ways to prepare for induction problems. The use of fiber-optic networks can limit damage. To the knowledge of the authors, these are the first cases of lightning striking hospitals in medical literature. PMID:20066646
Macieira-Coelho, E; Garcia-Alves, M; da Costa, B; Cantinho, G; Pedro, P; Dionisio, I; Gouveia, A; de Padua, F
1997-04-01
Controversy remains in considering non-Q wave myocardial infarction (NQMI) a distinct pathophysiological entity of Q wave myocardial infarction (QMI). In order to analyze the severity of coronary artery disease, extension of myocardial scar or myocardial ischemia and ventricular function, 78 consecutive patients with QMI and 32 with NQMI, mean age 55.4 +/- 8.5, not submitted to thrombolytic therapy, were studied. Coronary angiography, exercise thallium scintigraphy and radionuclide ventriculography were performed in all at least within 3 months of a prior myocardial infarction. In the present study the occurrence of QMI was significantly more frequent in older patients than NQMI. There was no prevalence of occlusion either in the right, left circumflex or left anterior descending coronary arteries in both groups. Ejection fraction, degree of occlusion and presence of collateral circulation showed an equal prevalence in QMI and NQMI patients. A higher incidence of multivessel disease was found in NQMI that had less necrosis than QMI patients. The prevalence of exercise induced thallium-201 redistribution defects within the infarct zone was substantially higher and involved more scar segments in NQMI patients. Physiological and clinical consequences of coronary thrombosis depends on the size and the number of diseased arteries, the approach the pathophysiologic consequences of coronary disease in terms of fractal structure has been suggested. A pronounced heterogeneity in regional myocardial blood flow in a fractal branching arterial network may be responsible for the pathophysiologic differences of coronary thrombosis between Q-wave and non Q-wave infarction. PMID:9341032
Impact of topographic internal lee wave drag on an eddying global ocean model
NASA Astrophysics Data System (ADS)
Trossman, David S.; Arbic, Brian K.; Richman, James G.; Garner, Stephen T.; Jayne, Steven R.; Wallcraft, Alan J.
2016-01-01
The impact of topographic internal lee wave drag (wave drag hereafter) on several aspects of the low-frequency circulation in a high-resolution global ocean model forced by winds and air-sea buoyancy fluxes is examined here. The HYbrid Coordinate Ocean Model (HYCOM) is run at two different horizontal resolutions (one nominally 1/12° and the other 1/25°). Wave drag, which parameterizes both topographic blocking and the generation of lee waves arising from geostrophic flow impinging upon rough topography, is inserted into the simulations as they run. The parameterization used here affects the momentum equations and hence the structure of eddy kinetic energy. Lee waves also have implications for diapycnal mixing in the ocean, though the parameterization does not directly modify the density. Total near-bottom energy dissipation due to wave drag and quadratic bottom boundary layer drag is nearly doubled, and the energy dissipation due to quadratic bottom drag is reduced by about a factor of two, in simulations with an inserted wave drag compared to simulations having only quadratic bottom drag. With the insertion of wave drag, the kinetic energy is reduced in the abyss and in a three-dimensional global integral. Deflection by partial topographic blocking is inferred to be one reason why the near-bottom kinetic energy can increase in locations where there is little change in dissipation by quadratic bottom drag. Despite large changes seen in the abyss, the changes that occur near the sea surface are relatively small upon insertion of wave drag into the simulations. Both the sea surface height variance and geostrophic surface kinetic energy are reduced on global average by more than twice the seasonal variability in these diagnostics. Alterations in the intensified jet positions brought about by inserting wave drag are not distinguishable from the temporal variability of jet positions. Various statistical measures suggest that applying wave drag only within a fixed distance from the seafloor is not detrimental to the model performance relative to observations. However, the introduction of a novel diagnostic suggests that one way to improve the wave drag parameterization is to allow the vertical deposition of lee wave momentum flux to be spatially heterogeneous.
Impact of ozone depletion on immune function
Jeevan, A.; Kripke, M.L. . Dept. of Immunology)
1993-06-01
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.
NASA Astrophysics Data System (ADS)
Shang, Xuefeng; de Hoop, Maarten V.; van der Hilst, Robert D.
2012-08-01
We present a wave equation prestack depth migration to image crust and mantle structures using multi-component earthquake data recorded at dense seismograph arrays. Transmitted P and S waves recorded on the surface are back propagated using an elastic wave equation solver. The wave modes are separated after the reverse-time continuation of the wavefield from the surface, and subjected to a (cross-correlation type) imaging condition forming an inverse scattering transform. Reverse time migration (RTM) does not make assumptions about the presence or properties of interfaces - notably, it does not assume that interfaces are (locally) horizontal. With synthetic experiments, and different background models, we show that passive source RTM can reconstruct dipping and vertically offset interfaces even in the presence of complex wave phenomena (such as caustics and point diffraction) and that its performance is superior to traditional receiver function analysis, e.g., common conversion point (CCP) stacking, in complex geological environments.
NASA Astrophysics Data System (ADS)
Balram, Ajit C.; Jain, J. K.
2016-02-01
The microscopic wave functions of the composite fermion theory can incorporate electron mass anisotropy by a trivial rescaling of the coordinates. These wave functions are very likely adiabatically connected to the actual wave functions of the anisotropic fractional quantum Hall states. We show in this paper that they possess the nice property that their energies can be analytically related to the previously calculated energies for the isotropic states through a universal scale factor, thus allowing an estimation of several observables in the thermodynamic limit for all fractional quantum Hall states as well as the composite fermion Fermi sea. The rather weak dependence of the scale factor on the anisotropy provides insight into why fractional quantum Hall effect and composite fermions are quite robust to electron mass anisotropy. We discuss how better, though still approximate, wave functions can be obtained by introducing a variational parameter, following Haldane [F. D. M. Haldane, Phys. Rev. Lett. 107, 116801 (2011), 10.1103/PhysRevLett.107.116801], but the resulting wave functions are not readily amenable to calculations. Our considerations are also applicable, with minimal modification, to the case where the dielectric function of the background material is anisotropic.
Lerma H, S.
2010-07-15
The structure of the exact wave function of the isovectorial pairing Hamiltonian with nondegenerate single-particle levels is discussed. The way that the single-particle splittings break the quartet condensate solution found for N=Z nuclei in a single degenerate level is established. After a brief review of the exact solution, the structure of the wave function is analyzed and some particular cases are considered where a clear interpretation of the wave function emerges. An expression for the exact wave function in terms of the isospin triplet of pair creators is given. The ground-state wave function is analyzed as a function of pairing strength, for a system of four protons and four neutrons. For small and large values of the pairing strength a dominance of two-pair (quartets) scalar couplings is found, whereas for intermediate values enhancements of the nonscalar couplings are obtained. A correlation of these enhancements with the creation of Cooper-like pairs is observed.
A spectral Phase-Amplitude method for propagating a wave function to large distances
NASA Astrophysics Data System (ADS)
Rawitscher, George
2015-06-01
The phase and amplitude (Ph-A) of a wave function vary slowly with distance, in contrast to the wave function that can be highly oscillatory. Hence the Ph-A representation of a wave function requires far fewer computational mesh points than the wave function itself. In 1930 Milne presented an equation for the phase and the amplitude functions (which is different from the one developed by Calogero), and in 1962 Seaton and Peach solved these equations iteratively. The objective of the present study is to implement Seaton and Peach's iteration procedure with a spectral Chebyshev expansion method, and at the same time present a non-iterative analytic solution to an approximate version of the iterative equations. The iterations converge rapidly for the case of attractive potentials. Two numerical examples are given: (1) for a potential that decreases with distance as 1 /r3, and (2) a Coulomb potential ∝ 1 / r. In both cases the whole radial range of [0-2000] requires only between 25 and 100 mesh points and the corresponding accuracy is between 10-3 and 10-6. The 0th iteration (which is the WKB approximation) gives an accuracy of 10-2. This spectral method permits one to calculate a wave function out to large distances reliably and economically.
Extracting a shape function for a signal with intra-wave frequency modulation.
Hou, Thomas Y; Shi, Zuoqiang
2016-04-13
In this paper, we develop an effective and robust adaptive time-frequency analysis method for signals with intra-wave frequency modulation. To handle this kind of signals effectively, we generalize our data-driven time-frequency analysis by using a shape function to describe the intra-wave frequency modulation. The idea of using a shape function in time-frequency analysis was first proposed by Wu (Wu 2013 Appl. Comput. Harmon. Anal. 35, 181-199. (doi:10.1016/j.acha.2012.08.008)). A shape function could be any smooth 2π-periodic function. Based on this model, we propose to solve an optimization problem to extract the shape function. By exploring the fact that the shape function is a periodic function with respect to its phase function, we can identify certain low-rank structure of the signal. This low-rank structure enables us to extract the shape function from the signal. Once the shape function is obtained, the instantaneous frequency with intra-wave modulation can be recovered from the shape function. We demonstrate the robustness and efficiency of our method by applying it to several synthetic and real signals. One important observation is that this approach is very stable to noise perturbation. By using the shape function approach, we can capture the intra-wave frequency modulation very well even for noise-polluted signals. In comparison, existing methods such as empirical mode decomposition/ensemble empirical mode decomposition seem to have difficulty in capturing the intra-wave modulation when the signal is polluted by noise. PMID:26953176
A test of a mechanical multi-impact shear-wave seismic source
Worley, David M.; Odum, Jack K.; Williams, Robert A.; Stephenson, William J.
2001-01-01
We modified two gasoline-engine-powered earth tampers, commonly used as compressional-(P) wave seismic energy sources for shallow reflection studies, for use as shear(S)-wave energy sources. This new configuration, termed ?Hacker? (horizontal Wacker?), is evaluated as an alternative to the manual sledgehammer typically used in conjunction with a large timber held down by the front wheels of a vehicle. The Hacker maximizes the use of existing equipment by a quick changeover of bolt-on accessories as opposed to the handling of a separate source, and is intended to improve the depth of penetration of S-wave data by stacking hundreds of impacts over a two to three minute period. Records were made with a variety of configurations involving up to two Hackers simultaneously then compared to a reference record made with a sledgehammer. Preliminary results indicate moderate success by the higher amplitude S-waves recorded with the Hacker as compared to the hammer method. False triggers generated by the backswing of the Hacker add unwanted noise and we are currently working to modify the device to eliminate this effect. Correlation noise caused by insufficient randomness of the Hacker impact sequence is also a significant noise problem that we hope to reduce by improving the coupling of the Hacker to the timber so that the operator has more control over the impact sequence.
Impact of weightlessness on muscle function
NASA Technical Reports Server (NTRS)
Tischler, M. E.; Slentz, M.
1995-01-01
The most studied skeletal muscles which depend on gravity, "antigravity" muscles, are located in the posterior portion of the legs. Antigravity muscles are characterized generally by a different fiber type composition than those which are considered nonpostural. The gravity-dependent function of the antigravity muscles makes them particularly sensitive to weightlessness (unweighting) resulting in a substantial loss of muscle protein, with a relatively greater loss of myofibrillar (structural) proteins. Accordingly alpha-actin mRNA decreases in muscle of rats exposed to microgravity. In the legs, the soleus seems particularly responsive to the lack of weight-bearing associated with space flight. The loss of muscle protein leads to a decreased cross-sectional area of muscle fibers, particularly of the slow-twitch, oxidative (SO) ones compared to fast-twitch glycolytic (FG) or oxidative-glycolytic (FOG) fibers. In some muscles, a shift in fiber composition from SO to FOG has been reported in the adaptation to spaceflight. Changes in muscle composition with spaceflight have been associated with decreased maximal isometric tension (Po) and increased maximal shortening velocity. In terms of fuel metabolism, results varied depending on the pathway considered. Glucose uptake, in the presence of insulin, and activities of glycolytic enzymes are increased by space flight. In contrast, oxidation of fatty acids may be diminished. Oxidation of pyruvate, activity of the citric acid cycle, and ketone metabolism in muscle seem to be unaffected by microgravity.
Hormonal profile impact on female sexual function in young women
NASA Astrophysics Data System (ADS)
Stoian, Dana; Craciunescu, Mihalea; Craina, Marius; Pater, Liana; Pater, Flavius
2014-12-01
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.
NASA Technical Reports Server (NTRS)
Baumeiste, K. J.
1983-01-01
A time-dependent finite difference formulation to the inhomogeneous wave equation is derived for plane wave propagation with harmonic noise sources. The difference equation and boundary conditions are developed along with the techniques to simulate the Dirac delta function associated with a concentrated noise source. Example calculations are presented for the Green's function and distributed noise sources. For the example considered, the desired Fourier transformed acoustic pressures are determined from the transient pressures by use of a ramping function and an integration technique, both of which eliminates the nonharmonic pressure associated with the initial transient.
NASA Technical Reports Server (NTRS)
Baumeister, K. J.
1983-01-01
A time-dependent finite difference formulation to the inhomogeneous wave equation is derived for plane wave propagation with harmonic noise sources. The difference equation and boundary conditions are developed along with the techniques to simulate the Dirac delta function associated with a concentrated noise source. Example calculations are presented for the Green's function and distributed noise sources. For the example considered, the desired Fourier transformed acoustic pressures are determined from the transient pressures by use of a ramping function and an integration technique, both of which eliminates the nonharmonic pressure associated with the initial transient.
Basis of symmetric polynomials for many-boson light-front wave functions.
Chabysheva, Sophia S; Hiller, John R
2014-12-01
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 ϕ(4) theory illustrates the use of these polynomials. PMID:25615225
Basis of symmetric polynomials for many-boson light-front wave functions
NASA Astrophysics Data System (ADS)
Chabysheva, Sophia S.; Hiller, John R.
2014-12-01
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 ϕ4 theory illustrates the use of these polynomials.
Wave function in the presence of constraints: Persistent current in coupled rings
NASA Astrophysics Data System (ADS)
Schmeltzer, D.; Saxena, Avadh
2010-05-01
Using a method introduced earlier, we compute the wave function in the presence of constraints. As an explicit example we compute the wave function for the many electrons problem in coupled metallic rings in the presence of external magnetic fluxes. For equal fluxes and an even number of electrons the constraints enforce a wave function with a vanishing total momentum and a large persistent current and magnetization in contrast to the odd number of electrons where at finite temperatures the current is suppressed. We propose that the even-odd property can be verified by measuring the magnetization as a function of a varying gate voltage coupled to the rings. By reversing the flux in one of the rings the current and magnetization vanish in both rings; this can be potentially used as a nonlocal control device.
Manipulation of terahertz waves by work function engineering in metal-graphite structures
NASA Astrophysics Data System (ADS)
Irfan, Muhammad; Lee, Soo Kyung; Yim, Jong-Hyuk; Lee, Yong Tak; Jho, Young-Dahl
2016-04-01
We manipulate the transient terahertz (THz) waves emitted from metal-graphite interfaces, where potential barriers were formed because of work function differences. To flip the phase of the THz waves, two distinct groups of metals were evaporated on n-type doped highly oriented pyrolytic graphite (HOPG): group A, which consisted of Pt, Au, and Ag with work functions larger than that of HOPG and group B, which consisted of Al and Ti with work functions smaller than that of HOPG. The phase of the transient THz lineshapes from group A was opposite to that of group B under infrared laser excitation, which is indicative of opposite band bending and concomitant interfacial doping for ambipolar transport at the metal-graphite junctions. The amplitude of the THz waves could also be manipulated by the work function differences and further quantified based on modified minority carrier mobilities at the depletion regions.
Perturbative QCD fragmentation functions for production of [ital P]-wave charm and bottom mesons
Yuan, T.C. )
1994-11-01
We calculate the leading order QCD fragmentation functions for the production of [ital P]-wave charmed [ital b] mesons. Long-distance effects are factored into two nonperturbative parameters: the derivative of the radial wave function at the origin and a second parameter related to the probability for a ([ital [bar b]c]) heavy quark pair that is produced in a color-octet [ital S]-wave state to form a color-singlet [ital P]-wave bound state. The four 2[ital P] states and those 3[ital P] states which lie below the [ital BD] flavor threshold eventually all decay into the 1[ital S] ground state [ital B][sub [ital c
Impacts and Responses to the 1995 Heat Wave: A Call to Action.
NASA Astrophysics Data System (ADS)
Changnon, Stanley A.; Kunkel, Kenneth E.; Reinke, Beth C.
1996-07-01
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.
Impact of heat waves on nonaccidental deaths in Jinan, China, and associated risk factors
NASA Astrophysics Data System (ADS)
Zhang, Jun; Liu, Shouqin; Han, Jing; Zhou, Lin; Liu, Yueling; Yang, Liu; Zhang, Ji; Zhang, Ying
2016-01-01
An ecological study and a case-crossover analysis were conducted to evaluate the impact of heat waves on nonaccidental deaths, and to identify contributing factors of population vulnerability to heat-related deaths in Jinan, China. Daily death data and meteorological data were collected for summer months (June to August) of 2012-2013. Excess mortality was calculated and multivariate linear regression models were used to assess the increased risk of heat waves on deaths. Univariate and multivariate logistic regression models were performed to estimate the odd ratios (ORs) of risk factors and their 95 % confidence intervals (CIs). Overall, heat waves were related to 24.88 % excess deaths of total nonaccidental deaths and 31.33 % excess deaths of circulatory diseases, with an OR of 16.07 (95 % CI 8.80-23.33) for total nonaccidental deaths and 12.46 (95 % CI 7.39-17.53) for deaths of circulatory diseases. The case-crossover analysis indicated that older people were more likely to die during heat waves (OR = 1.233, 95 % CI 1.076-1.413) and more deaths occurred outside a hospital during heat waves (OR = 1.142, 95 % CI 1.006-1.296). In conclusion, heat waves have caused excess deaths and significantly increased the risk of circulatory deaths. The risk factors identified in our study have implications for public health interventions to reduce heat-related mortality during extreme heat events.
Dynamical model for longitudinal wave functions in light-front holographic QCD
Chabysheva, Sophia S.; Hiller, John R.
2013-10-15
We construct a Schrödinger-like equation for the longitudinal wave function of a meson in the valence qq{sup -bar} sector, based on the ’t Hooft model for large-N two-dimensional QCD, and combine this with the usual transverse equation from light-front holographic QCD, to obtain a model for mesons with massive quarks. The computed wave functions are compared with the wave function ansatz of Brodsky and de Téramond and used to compute decay constants and parton distribution functions. The basis functions used to solve the longitudinal equation may be useful for more general calculations of meson states in QCD. -- Highlights: •Provide relativistic quark model based on light-front holographic QCD. •Incorporate dependence on quark mass. •Consistent with the Brodsky–de Téramond quark-wave-function ansatz. •Compute meson decay constants and parton distribution functions. •Illustrate use of basis functions that could be convenient for more general numerical calculations in light-front QCD.
Impact of ectonucleotidases in autonomic nervous functions.
Cardoso, Andria Machado; Schetinger, Maria Rosa Chitolina; Correia-de-S, Paulo; Svigny, Jean
2015-09-01
Adenine and uracil nucleotides play key functions in the autonomic nervous system (ANS). For instance, ATP acts as a neurotransmitter, co-transmitter and neuromodulator in the ANS. The purinergic system encompasses (1) receptors that respond to extracellular purines, which are designated as P1 and P2 purinoceptors, (2) purine release and uptake, and (3) a cascade of enzymes that regulate the concentration of purines near the cell surface. Ectonucleotidases and adenosine deaminase (ADA) are enzymes responsible for the hydrolysis of ATP (and other nucleotides such as ADP, UTP, UDP, AMP) and adenosine, respectively. Accordingly, these enzymes are expected to play an important role in the control of neuro-effector transmission in tissues innervated by both the sympathetic and parasympathetic divisions of the ANS. Indeed, ectonucleotidases have the ability to either terminate P2 receptor responses initiated by nucleoside triphosphates (ATP and UTP), and/or to favor the activation of ADP (e.g. P2Y1,12,13) and UDP (e.g. P2Y6) and/or adenosine (P1) specific receptors. In addition, ectonucleotidases can also importantly protect some P2 receptors from desensitization (e.g. P2X1, P2Y1). In this review, we present the (putative) roles of ectonucleotidases and ADA in the ANS with a focus on their regulatory activity at neuro-effector junctions in the following tissues: heart, vas deferens, urinary bladder, salivary glands, blood vessels and the intestine. We also present their implication in nociceptive transmission. PMID:26008223
Initial survey of the wave distribution functions for plasmaspheric hiss observed by ISEE 1
Storey, L.R.O. ); Lefeuvre, F.; Parrot, M.; Cairo, L. ); Anderson, R.R. )
1991-11-01
Multicomponent ELF/VLF wave data from the ISEE 1 satellite have been analyzed with the aim of identifying the generation mechanism of plasmaspheric hiss, and especially of determining whether it involves wave propagation of cyclic trajectories. The data were taken from four passes of the satellite, of which two were close to the geomagnetic equatorial plane and two were farther from it; all four occurred during magnetically quiet periods. The principal method of analysis was calculation of the wave distribution functions. The waves appear to have been generated over a wide range of altitudes within the plasmasphere, and most, though not all, of them were propagating obliquely with respect to the Earth's magnetic field. On one of the passes near the equator, some wave energy was observed at small wave normal angles, and these waves may have been propagating on cyclic trajectories. Even here, however, obliquely propagating waves were predominant, a finding that is difficult to reconcile with the classical quasi-linear generation mechanism or its variants. The conclusion is that another mechanism, probably nonlinear, must have been generating most of the hiss observed on these four passes.
NASA Astrophysics Data System (ADS)
Kysely, J.; Kim, J.
2010-03-01
The study deals with mortality impacts of the July-August 1994 heat wave in the population of South Korea, including the megacity of Seoul (with the population exceeding 10 million for the city and 20 million for the metropolitan area), and estimates recurrence probability of the heat wave in a changing climate in terms of simulations of daily temperature series with a stochastic model. The 1994 heat wave is found exceptional with respect to both climatological characteristics and the mortality effects: significantly elevated mortality occurred in all population groups, including children up to 14 years of age, and the total death toll exceeded 3000 in the Korean population, which ranks the 1994 heat wave among the worst weather-related disasters in East Asia. The estimate represents net excess mortality as no mortality displacement effect appeared. A comparison with other documented natural disasters shows that the death toll of the heat wave was much higher than those of the most disastrous floodings and typhoons over Korean Peninsula in the 20th century. The mortality response was stronger in males than females although males are found to be less vulnerable during average heat waves. A climatological analysis reveals that the July-August 1994 heat wave might be considered an extremely rare event with a return period in the order of hundreds of years if stationarity of temperature time series is assumed. However, under a more realistic assumption of gradual warming related to climate change, recurrence probability of an event analogous to the 1994 heat wave sharply rises for near-future time horizons. If warming of 0.04°C/year is assumed over 2001-2060, the recurrence interval of a very long spell of days with temperature exceeding a high threshold (as in the 1994 heat wave) is estimated to decrease to around 40 (10) years in the 2021-2030 (2041-2050) decade. This emphasizes the need for setting up an efficient heat-watch-warning system in this area in order to reduce human mortality impacts of heat waves.
Experimental study on impact-induced seismic wave propagation through granular materials
NASA Astrophysics Data System (ADS)
Yasui, Minami; Matsumoto, Eri; Arakawa, Masahiko
2015-11-01
Impact-induced seismic waves are supposed to cause movements of regolith particles, resulting in modifications of asteroidal surfaces. The imparted seismic energy is thus a key parameter to determining the scale and magnitude of this seismic shaking process. It is important to study the propagation velocity, attenuation rate, and vibration period of the impact-induced seismic wave to estimate the seismic energy. Hence, we conducted impact cratering experiments at Kobe University using a 200-μm glass beads target to simulate a regolith layer, and measured the impact-induced seismic wave using three accelerometers set on the target surface at differences ranging from 3.2 to 12.7 cm. The target was impacted with three kinds of projectiles at ˜100 m s-1 using a one-stage gas gun. The propagation velocity of the seismic wave in the beads target was 108.9 m s-1, and the maximum acceleration, gmax, in the unit of m s-2, measured by each accelerometer showed good correlation with the distance from the impact point normalized by the crater radius, x/R, irrespective of projectile type. They also were fitted by one power-law equation, gmax = 102.19 (x/R)-2.21. The half period of the first peak of the measured seismic waves was ˜0.72 ms, and this duration was almost consistent with the penetration time of each projectile into the target. According to these measurements, we estimated the impact seismic efficiency factor, that is, the ratio of seismic energy to kinetic energy of the projectile, to be almost constant, 5.7 × 10-4 inside the crater rim, while it exponentially decreased with distance from the impact point outside the crater rim. At a distance quadruple of the crater radius, the efficiency factors were 4.4 × 10-5 for polycarbonate projectile and 9.5 × 10-5 for alumina and stainless steel projectiles.
Impacts of enhanced central Pacific ENSO on wave climate and headland-bay beach morphology
NASA Astrophysics Data System (ADS)
Mortlock, Thomas R.; Goodwin, Ian D.
2016-06-01
Wave climate and Pacific basin coastal behaviour associated with El Niño Southern Oscillation (ENSO) is understood at a reconnaissance level, but the coastal response to different central Pacific (CP) versus eastern Pacific (EP) flavours of ENSO is unknown. We show that CP ENSO events produce different patterns of directional wave power to EP ENSO along the southeast Australian shelf and southwest Pacific region, because of significant variability in trade-wind wave generation. The modulation of the trade wind wave climate during CP ENSO has thus far been neglected in existing coastal process studies. We also show that coastal change between CP and EP ENSO cannot be inferred from shifts in the deepwater wave climate. This is because variability in trade wind wave generation is masked in deepwater by the persistence of high power extra-tropical waves that have reduced impact on nearshore processes due to high wave refraction. Morphodynamic modelling in a headland-bay beach indicates that CP ENSO leads to higher coastal erosion potential and slower post-storm recovery than EP ENSO during an El Niño/La Niña cycle. We show that the alongshore variability in beach morphological type can be used to model the static equilibrium planform response for each ENSO phase. Results indicate that shoreline response to ENSO in most headland-bay beach coasts is not as simple as the existing paradigm that (anti-) clockwise rotation occurs during El Niño (La Niña). Our methods provide a second-order approach to project coastal response and predict the discrete shoreline rotations for ENSO flavours.
NASA Astrophysics Data System (ADS)
Lognonne, P.; Gudkova, T.; Le Feuvre, M.; Garcia, R. F.; Kawamura, T.; Banerdt, B.; Kobayashi, N.
2011-12-01
Natural Impacts occurring on the surface of telluric planets are important seismic sources for constraining the crustal and upper mantle structure, especially when their impact location and impacting time can be determined by other complementing experiments, such as Earth based flash detection for the Moon or differential orbital imaging of the surface for Mars. When these complementary data are not available, which was the case of Apollo with the exception of artificial impacts, the location of impact as compared to quake is easier, as only their geographical location must be determined from seismic data. We present recent results of the analysis of impact related seismic data gathered by the Apollo Lunar seismic network during the 70th. By using the artificial impact, we first develop a calibrated analysis for extracting the impulse (i.e. mass time impact velocity) from the amplitude of seismic waves, and point out the effect of the generation of ejecta in the seismic impulse. This approach not only allows to constrain the mass of the impacts, but also to constrain the impact frequency-impactor mass relation. By combining both the Apollo long period and short period data, further analysis can be made on the dynamic of the seismic source. The combination of these date provides indeed broadband seismic analysis have been made allowing to constraint the seismic cut-off frequency and source spectrum associated with both natural and artificial impacts. We show that the source cut-off is, as compared to moonquakes, relatively low and around a few Hz for remotely detected impacts. It is also depending not only on the impact size, but also on the impact location, as the seismic radiation of the shock wave depends on the most-upper regolith layers. We finally use our results and forward modeling to prepare the GEMS seismic mission to Mars, considered by NASA for a launch in 2016. In order to have a robust estimation of the rates of seismic detection of impacts, we analyze and model the differences of seismic propagation properties between Mars and the Moon, and use this modeling to estimate the seismic response of impacts on Mars, as a function of both the impactor characteristics (mass and velocity) and epicentral distance. We then use statistical models of impactors, confirmed by both the Apollo seismic observations and the Mars Orbiter impacts observations, to estimate the present flux on Mars and to constrain the rate of seismic impact detection, as well as the expected probability to further locale these events by differential remote sensing. This analysis is performed by taking into account both the expected performances of the VBB seismometer of GEMS and the expected environmental noise after its deployment on the Martian surface. The perspectives in terms of crustal and upper mantle seismic imaging are finally provided in conclusion for both GEMS on Mars and SELENE2 on the Moon.
Harvey, E. Newton; McMillen, J. Howard
1947-01-01
The spark shadowgram method of studying shock waves is described. It has been used to investigate the properties of such waves produced by the impact of a high velocity missile on the surface of water. The method can be adapted for study of behavior of shock waves in tissue by placing the tissue on a water surface or immersing it in water. Spark shadowgrams then reveal waves passing from tissue to water or reflected from tissue surfaces. Reflection and transmission of shock waves from muscle, liver, stomach, and intestinal wall are compared with reflection from non-living surfaces such as gelatin gel, steel, plexiglas, cork, and air. Because of its heterogeneous structure, waves transmitted by tissue are dispersed and appear as a series of wavelets. When the accoustical impedance (density x wave velocity) of a medium is less than that in which the wave is moving, reflection will occur with inversion of the wave; i.e., a high pressure wave will become a low pressure wave. This inversion occurs at an air surface and is illustrated by shadowgrams of reflection from stomach wall, from a segment of colon filled with gas, and from air-filled rubber balloons. Bone (human skull and beef ribs) shows good reflection and some transmission of shock waves. When steel is directly hit by a missile, clearly visible elastic waves pass from metal to water, but a similar direct hit on bone does not result in elastic waves strong enough to be detected by a spark shadowgram. PMID:19871617
Wave functions and two-electron probability distributions of the Hooke's-law atom and helium
O'Neill, Darragh P.; Gill, Peter M. W.
2003-08-01
The Hooke's-law atom (hookium) provides an exactly soluble model for a two-electron atom in which the nuclear-electron Coulombic attraction has been replaced by a harmonic one. Starting from the known exact position-space wave function for the ground state of hookium, we present the momentum-space wave function. We also look at the intracules, two-electron probability distributions, for hookium in position, momentum, and phase space. These are compared with the Hartree-Fock results and the Coulomb holes (the difference between the exact and Hartree-Fock intracules) in position, momentum, and phase space are examined. We then compare these results with analogous results for the ground state of helium using a simple, explicitly correlated wave function.
NASA Astrophysics Data System (ADS)
Casanova, David; Krylov, Anna I.
2016-01-01
A new method for quantifying the contributions of local excitation, charge resonance, and multiexciton configurations in correlated wave functions of multichromophoric systems is presented. The approach relies on fragment-localized orbitals and employs spin correlators. Its utility is illustrated by calculations on model clusters of hydrogen, ethylene, and tetracene molecules using adiabatic restricted-active-space configuration interaction wave functions. In addition to the wave function analysis, this approach provides a basis for a simple state-specific energy correction accounting for insufficient description of electron correlation. The decomposition scheme also allows one to compute energies of the diabatic states of the local excitonic, charge-resonance, and multi-excitonic character. The new method provides insight into electronic structure of multichromophoric systems and delivers valuable reference data for validating excitonic models.
Electronic structure and correlated wave functions of a few electron quantum dots
Sako, Tokuei; Ishida, Hiroshi; Fujikawa, Kazuo
2015-01-22
The energy spectra and wave functions of a few electrons confined by a quasi-one-dimensional harmonic and anharmonic potentials have been studied by using a full configuration interaction method employing a Cartesian anisotropic Gaussian basis set. The energy spectra are classified into three regimes of the strength of confinement, namely, large, medium and small. The polyad quantum number defined by a total number of nodes in the wave functions is shown to be a key ingredient to interpret the energy spectra for the whole range of the confinement strength. The nodal pattern of the wave functions exhibits normal modes for the harmonic confining potential, indicating collective motions of electrons. These normal modes are shown to undergo a transition to local modes for an anharmonic potential with large anharmonicity.
Mapping an electron wave function by a local electron scattering probe
NASA Astrophysics Data System (ADS)
Reichl, C.; Dietsche, W.; Tschirky, T.; Hyart, T.; Wegscheider, W.
2015-11-01
A technique is developed which allows for the detailed mapping of the electronic wave function in two-dimensional electron gases with low-temperature mobilities up to 15× {10}6 {{cm}}2 {{{V}}}-1 {{{s}}}-1. Thin (‘delta’) layers of aluminium are placed into the regions where the electrons reside. This causes electron scattering which depends very locally on the amplitude of the electron wave function at the position of the Al δ-layer. By changing the distance of this layer from the interface we map the shape of the wave function perpendicular to the interface. Despite having a profound effect on the electron mobiliy, the δ-layers do not cause a widening of the quantum Hall plateaus.
Casanova, David; Krylov, Anna I
2016-01-01
A new method for quantifying the contributions of local excitation, charge resonance, and multiexciton configurations in correlated wave functions of multichromophoric systems is presented. The approach relies on fragment-localized orbitals and employs spin correlators. Its utility is illustrated by calculations on model clusters of hydrogen, ethylene, and tetracene molecules using adiabatic restricted-active-space configuration interaction wave functions. In addition to the wave function analysis, this approach provides a basis for a simple state-specific energy correction accounting for insufficient description of electron correlation. The decomposition scheme also allows one to compute energies of the diabatic states of the local excitonic, charge-resonance, and multi-excitonic character. The new method provides insight into electronic structure of multichromophoric systems and delivers valuable reference data for validating excitonic models. PMID:26747796
Many-body localization transition in Rokhsar-Kivelson-type wave functions
NASA Astrophysics Data System (ADS)
Chen, Xiao; Yu, Xiongjie; Cho, Gil Young; Clark, Bryan K.; Fradkin, Eduardo
2015-12-01
We construct a family of many-body wave functions to study the many-body localization phase transition. The wave functions have a Rokhsar-Kivelson form, in which the weight for the configurations are chosen from the Gibbs weights of a classical spin glass model, known as the random energy model, multiplied by a random sign structure to represent a highly excited state. These wave functions show a phase transition into an MBL phase. In addition, we see three regimes of entanglement scaling with the subsystem size: scaling with the entanglement corresponding to an infinite temperature thermal phase, constant scaling, and a subextensive scaling between these limits. Near the phase transition point, the fluctuations of the Rényi entropies are non-Gaussian. We find that Rényi entropies with different Rényi index transition into the MBL phase at different points and have different scaling behavior, suggesting a multifractal behavior.
The effect of wave-induced turbulence on intertidal mudflats: Impact of boat traffic and wind
NASA Astrophysics Data System (ADS)
Verney, R.; Deloffre, J.; Brun-Cottan, J.-C.; Lafite, R.
2007-03-01
Semi-diurnal and fortnightly surveys were carried out to quantify the effects of wind- and navigation-induced high-energy events on bed sediments above intertidal mudflats. The mudflats are located in the upper fluvial part (Oissel mudflat) and at the mouth (Vasière Nord mudflat) of the macrotidal Seine estuary. Instantaneous flow velocities and mudflat bed elevation were measured at a high frequency and high resolution with an acoustic doppler velocimeter (ADV) and an ALTUS altimeter, respectively. Suspended particulate matter concentrations were estimated by calibrating the ADV acoustic backscattered intensity with bed sediments collected at the study sites. Turbulent bed shear stress values were estimated by the turbulent kinetic energy method, using velocity variances filtered from the wave contribution. Wave shear stress and maximum wave-current shear stress values were calculated with the wave-current interaction (WCI) model, which is based on the bed roughness length, wave orbital velocities and the wave period ( TS). In the fluvial part of the estuary, boat passages occurred unevenly during the surveys and were characterized by long waves ( TS>50 s) induced by the drawdown effect and by short boat-waves ( TS<10 s). Boat waves generated large bottom shear stress values of 0.5 N m -2 for 2-5 min periods and, in burst of several seconds, larger bottom shear stress values up to 1 N m -2. At the mouth of the estuary, west south-west wind events generated short waves ( TS<10 s) of HS values ranging from 0.1 to 0.3 m. In shallow-water environment (water depth <1.5 m), these waves produced bottom shear stress values between 1 and 2 N m -2. Wave-current shear stress values are one order of magnitude larger than the current-induced shear stress and indicate that navigation and wind are the dominant hydrodynamic forcing parameters above the two mudflats. Bed elevation and SPM concentration time series showed that these high energy events induced erosion processes of up to several centimetres. Critical erosion shear stress ( τce) values were determined from the SPM concentration and bed elevation measurements. Rough τce values were found above 0.2 N m -2 for the Oissel mudflat and about 1 N m -2 for the Vasière Nord mudflat. These results demonstrate the advantages of combining the measurement of instantaneous velocity and bed elevation to determine in situ the erosion and deposition processes as a function of bottom shear stress variations.
Kinetic correlation in the final-state wave function in photo-double-ionization of He
Otranto, S.; Garibotti, C. R.
2003-06-01
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.
Automatic determination of important mode-mode correlations in many-mode vibrational wave functions
NASA Astrophysics Data System (ADS)
König, Carolin; Christiansen, Ove
2015-04-01
We introduce new automatic procedures for parameterizing vibrational coupled cluster (VCC) and vibrational configuration interaction wave functions. Importance measures for individual mode combinations in the wave function are derived based on upper bounds to Hamiltonian matrix elements and/or the size of perturbative corrections derived in the framework of VCC. With a threshold, this enables an automatic, system-adapted way of choosing which mode-mode correlations are explicitly parameterized in the many-mode wave function. The effect of different importance measures and thresholds is investigated for zero-point energies and infrared spectra for formaldehyde and furan. Furthermore, the direct link between important mode-mode correlations and coordinates is illustrated employing water clusters as examples: Using optimized coordinates, a larger number of mode combinations can be neglected in the correlated many-mode vibrational wave function than with normal coordinates for the same accuracy. Moreover, the fraction of important mode-mode correlations compared to the total number of correlations decreases with system size. This underlines the potential gain in efficiency when using optimized coordinates in combination with a flexible scheme for choosing the mode-mode correlations included in the parameterization of the correlated many-mode vibrational wave function. All in all, it is found that the introduced schemes for parameterizing correlated many-mode vibrational wave functions lead to at least as systematic and accurate calculations as those using more standard and straightforward excitation level definitions. This new way of defining approximate calculations offers potential for future calculations on larger systems.
Multiple-Resonance Local Wave Functions for Accurate Excited States in Quantum Monte Carlo.
Zulfikri, Habiburrahman; Amovilli, Claudio; Filippi, Claudia
2016-03-01
We introduce a novel class of local multideterminant Jastrow-Slater wave functions for the efficient and accurate treatment of excited states in quantum Monte Carlo. The wave function is expanded as a linear combination of excitations built from multiple sets of localized orbitals that correspond to the bonding patterns of the different Lewis resonance structures of the molecule. We capitalize on the concept of orbital domains of local coupled-cluster methods, which is here applied to the active space to select the orbitals to correlate and construct the important transitions. The excitations are further grouped into classes, which are ordered in importance and can be systematically included in the Jastrow-Slater wave function to ensure a balanced description of all states of interest. We assess the performance of the proposed wave function in the calculation of vertical excitation energies and excited-state geometry optimization of retinal models whose π → π* state has a strong intramolecular charge-transfer character. We find that our multiresonance wave functions recover the reference values of the total energies of the ground and excited states with only a small number of excitations and that the same expansion can be flexibly used at very different geometries. Furthermore, significant computational saving can also be gained in the orbital optimization step by selectively mixing occupied and virtual orbitals based on spatial considerations without loss of accuracy on the excitation energy. Our multiresonance wave functions are therefore compact, accurate, and very promising for the calculation of multiple excited states of different character in large molecules. PMID:26761421
Orthogonality of embedded wave functions for different states in frozen-density embedding theory
NASA Astrophysics Data System (ADS)
Zech, Alexander; Aquilante, Francesco; Wesolowski, Tomasz A.
2015-10-01
Other than lowest-energy stationary embedded wave functions obtained in Frozen-Density Embedding Theory (FDET) [T. A. Wesolowski, Phys. Rev. A 77, 012504 (2008)] can be associated with electronic excited states but they can be mutually non-orthogonal. Although this does not violate any physical principles — embedded wave functions are only auxiliary objects used to obtain stationary densities — working with orthogonal functions has many practical advantages. In the present work, we show numerically that excitation energies obtained using conventional FDET calculations (allowing for non-orthogonality) can be obtained using embedded wave functions which are strictly orthogonal. The used method preserves the mathematical structure of FDET and self-consistency between energy, embedded wave function, and the embedding potential (they are connected through the Euler-Lagrange equations). The orthogonality is built-in through the linearization in the embedded density of the relevant components of the total energy functional. Moreover, we show formally that the differences between the expectation values of the embedded Hamiltonian are equal to the excitation energies, which is the exact result within linearized FDET. Linearized FDET is shown to be a robust approximation for a large class of reference densities.
Orthogonality of embedded wave functions for different states in frozen-density embedding theory.
Zech, Alexander; Aquilante, Francesco; Wesolowski, Tomasz A
2015-10-28
Other than lowest-energy stationary embedded wave functions obtained in Frozen-Density Embedding Theory (FDET) [T. A. Wesolowski, Phys. Rev. A 77, 012504 (2008)] can be associated with electronic excited states but they can be mutually non-orthogonal. Although this does not violate any physical principles--embedded wave functions are only auxiliary objects used to obtain stationary densities--working with orthogonal functions has many practical advantages. In the present work, we show numerically that excitation energies obtained using conventional FDET calculations (allowing for non-orthogonality) can be obtained using embedded wave functions which are strictly orthogonal. The used method preserves the mathematical structure of FDET and self-consistency between energy, embedded wave function, and the embedding potential (they are connected through the Euler-Lagrange equations). The orthogonality is built-in through the linearization in the embedded density of the relevant components of the total energy functional. Moreover, we show formally that the differences between the expectation values of the embedded Hamiltonian are equal to the excitation energies, which is the exact result within linearized FDET. Linearized FDET is shown to be a robust approximation for a large class of reference densities. PMID:26520497
Relativistic plane-wave Born theory and its application to electron-impact excitation
Fontes, Christopher J.; Zhang Honglin
2007-10-15
An exact treatment of the relativistic plane-wave Born (RPWB) cross section for electron-impact excitation is provided for an arbitrary atom or ion. This result represents an improvement over the cross section obtained from the widely used Bethe high-energy theory developed in the 1930s. The results obtained from this RPWB approach can be applied to a broad class of problems in fundamental electron-impact scattering theory. As an illustration, the approach is used to approximate the high-l, partial-wave contribution in more accurate calculations of the excitation cross section, a problem which has been lacking a fully relativistic treatment for more than 20 years.
Bernevig, B Andrei; Haldane, F D M
2009-02-13
We present model wave functions for quasielectron (as opposed to quasihole) excitations of the unitary Z_{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. PMID:19257618
Bernevig, B. Andrei; Haldane, F. D. M.
2009-02-13
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.
When valence bond wave functions are analyzed through QTAIM: Conceptual incompatibilities in H2
NASA Astrophysics Data System (ADS)
Ferro-Costas, David; Mosquera, Ricardo A.
2015-01-01
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.
Guided wave imaging for detection and evaluation of impact-induced delamination in composites
NASA Astrophysics Data System (ADS)
Tian, Zhenhua; Yu, Lingyu; Leckey, Cara; Seebo, Jeffrey
2015-10-01
In this paper, guided wavefield interactions with delamination damage in laminated composite panels are investigated. The frequency-wavenumber representations of the guided wavefields show that different wavenumbers are present in the delaminated plate, compared to a pristine case. The wavenumbers are correlated to trapped waves in the delamination region. Novel approaches for imaging the composite panels using guided waves are discussed and demonstrated for quantitative evaluation of the delamination damage. A filter reconstruction imaging method is shown to provide a rapid technique to locate delamination damage by showing where guided wave energy is trapped. A spatial wavenumber-based imaging algorithm is applied to calculate wavenumber values at each spatial location and highlights the delamination damage as regions with larger wavenumber values. The imaging approaches are demonstrated using experimental data from a plate with a simulated delamination (teflon insert) and from a plate containing impact-induced delamination damage. The methods are also applied to a multiple mode guided wave case to demonstrate application to complex wave cases.
NASA Astrophysics Data System (ADS)
Armstrong, B. N.; Warner, J. C.; He, R.
2008-12-01
We use a coupled ocean - wave (ROMS - SWAN) modeling system to investigate the impacts of storms on coastal environments. The models were run for the period from September 5 - 25, 2003 to simulate ocean conditions during hurricane Isabel. The model domain covered part of the western North Atlantic, including the entire east coast of the United States and the Gulf of Mexico. Boundary conditions were obtained from global models. Wind forcing combined NARR (North American Regional Reanalysis) and HRD (NOAA Hurricane Research Division of AOML) gridded surface wind. SWAN and ROMS were each run separately and then run as a coupled system to assess changes in the model output resulting from the simulation of a realistic scenario through exchange of current and wave information. Outputs from these models were compared with measured wave height, salinity, sea surface temperature (SST), and current time series data to assess improvements in prediction resulting from using a coupled modeling system. Results from the uncoupled models demonstrated good agreement with wave and current data series. Results from the coupled system showed increased wave heights in regions of strong currents such as the Gulf Stream. Coupled model wave heights decreased in the open ocean preceding tropical storm Fabian and Hurricane Isabel but showed a large increase in inlets when Isabel made landfall. Depth- averaged velocities showed improvement in the coupled model. Sea surface temperatures in the wake of the hurricane were more realistic for the coupled simulation because the ocean model used the wave heights in the surface roughness computation and this created an increased surface mixing.
A planetary ultra hypervelocity impact mechanics and shock wave science facility
NASA Technical Reports Server (NTRS)
Ahrens, Thomas J.
1987-01-01
Using the concept of intercepting orbits from a pair of Space Station serviced free flyers, a class of impact and shock wave experiments pertinent to planetary science can be performed. One proposed free flying vehicle is an impactor dispensor, and the second is the impact laboratory. How collision is achieved by utilizing essentially twice orbital velocity is demonstrated. The impactor dispensor contains a series of small flyer plates or other projectiles which are launched into the trajectory of the impactor laboratory at appropriate positions. The impactor laboratory is a large impact tank similar to those in terrestrial gun laboratories, except that it contains a supply of targets and instrumentation such as high speed cameras, flash X-ray apparatus, and digital recorders. Shock and isentropic pressures of up to 20 Mbar are achievable with such a system which provides 15 km/sec impact velocities for precisely oriented projectiles.
NASA Astrophysics Data System (ADS)
Azzellino, Arianna; Contestabile, Pasquale; Lanfredi, Caterina; Vicinanza, Diego
2010-05-01
The exploitation of renewable energy resources is fast becoming a key objective in many countries. Countries with coastlines have particularly valuable renewable energy resources in the form of tides, currents, waves and offshore wind. Due to the visual impact of siting large numbers of energy generating devices (eg. wind turbines) in terrestrial landscapes, considerable attention is now being directed towards coastal waters. Due to their environmental sensitivity, the selection of the most adequate location for these systems is a critical factor. Multi-criteria analysis allows to consider a wide variety of key characteristics (e.g. water depth, distance to shore, distance to the electric grid in land, geology, environmental impact) that may be converted into a numerical index of suitability for different WEC devices to different locations. So identifying the best alternative between an offshore or a onshore device may be specifically treated as a multicriteria problem. Special enphasisi should be given in the multicriteria analysis to the environmental impact issues. The wave energy prospective in the Italian seas is relatively low if compared to the other European countries faced to the ocean. Based on the wave climate, the Alghero site, (NW Sardinia, Italy) is one of the most interesting sites for the wave energy perspective (about 10 kW/m). Alghero site is characterized by a high level of marine biodiversity. In 2002 the area northern to Alghero harbour (Capo Caccia-Isola Piana) was established a Marine Protected Area (MPA). It could be discussed for this site how to choose between the onshore/offshore WEC alternative. An offshore device like Wave Dragon (http://www.wavedragon.net/) installed at -65m depth (width=300m and length=170 m) may approximately produce about 3.6 GWh/y with a total cost of about 9,000,000 €. On the other hand, an onshore device like SSG (http://waveenergy.no/), employed as crown wall for a vertical breakwater to enlarge the present harbour protection, and installed at -10m depth (length=300 m) may produce about 2.7 GWh/y with a total costs of about 12,000,000 €, where only the 50% of the amount are the costs of the SSG device. Obviously the environmental impact of the two solutions is quite different. Aim of this study is to provide a multicriteria decision support framework to evaluate the best WEC typology and location in the perspective of the environmental cost-benefit analysis. The general environmental aspects generated by wave power projects will be described. Colonisation patterns and biofouling will be discussed with particular reference to changes of the seabed and alterations due to new substrates. In addition, impacts for fish, fishery and marine mammals will be also considered. We suggest that wave power projects should be evaluated also on the basis of their environmental impacts in the perspective of the Strategic Environmental Assessment (SEA) analysis, as implemented by the European Commission (SEA Directive 2001/42/EC). The early incorporation of the environmental aspects involved in the evaluation of wave power projects will give the opportunity for early mitigations or design modifications, most likely making wave projects more acceptable in the long run and more suitable for the marine environment.
R wave amplitude during exercise. Relation to left ventricular function and coronary artery disease.
Baron, D W; Ilsley, C; Sheiban, I; Poole-Wilson, P A; Rickards, A F
1980-01-01
Change in R wave amplitude (mean delta R) was measured sequentially during and after 12 lead maximal treadmill exercise tests in 14 subjects with normal coronary arteries and 62 patients with coronary artery disease. In normal subjects mean delta R decreased maximally one minute after exercise and returned to control levels within three minutes. In contrast, mean delta R increased in patients with coronary artery disease, the greatest change occurring in patients with either triple vessel or left main disease or those with an akinetic region on the left ventriculogram. R wave amplitude returned to resting levels in five minutes. Increase in R wave amplitude was not directly related to changes in the ST segment. Changes in R wave amplitude during maximal treadmill exercise may improve the discrimination between patients with and without coronary artery disease and may help to identify those patients with abnormal left ventricular function. Images PMID:7437190
Influence of coastal vegetation on the 2004 tsunami wave impact in west Aceh
Laso Bayas, Juan Carlos; Marohn, Carsten; Dercon, Gerd; Dewi, Sonya; Piepho, Hans Peter; Joshi, Laxman; van Noordwijk, Meine; Cadisch, Georg
2011-01-01
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
Influence of coastal vegetation on the 2004 tsunami wave impact in west Aceh.
Laso Bayas, Juan Carlos; Marohn, Carsten; Dercon, Gerd; Dewi, Sonya; Piepho, Hans Peter; Joshi, Laxman; van Noordwijk, Meine; Cadisch, Georg
2011-11-15
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
Influence of coastal vegetation on the 2004 tsunami wave impact in west Aceh.
TOXLINE Toxicology Bibliographic Information
Laso Bayas JC; Marohn C; Dercon G; Dewi S; Piepho HP; Joshi L; van Noordwijk M; Cadisch G
2011-11-15
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.
Impact of boat generated waves over an estuarine intertidal zone of the Seine estuary (France)
NASA Astrophysics Data System (ADS)
Deloffre, Julien; Lafite, Robert
2015-04-01
Water movements in macrotidal estuaries are controlled by the tidal regime modulated seasonally by the fluvial discharge. Wind effect on hydrodynamics and sediment transport is also reported at the mouth. Besides estuaries are frequently man altered our knowledge on the human impact on hydrodynamics and sediment transport is less extended. As an example on the Seine estuary (France) port authorities have put emphasis on facilitating economic exchanges by means of embankment building and increased dredging activity over the last century. These developments led to secure sea vessel traffic in the Seine estuary but they also resulted in a change of estuarine hydrodynamics and sediment transport features. Consequences of boat generated waves are varied: increased water turbidity and sediment transfer, release of nutrient and contaminants in the water column, harmful to users, ecosystems and infrastructures generating important maintenance spending. The aim of this study is to analyse the impact of boat generated waves on sediment transport over an intertidal area. The studied site is located on the left bank in the fluvial part of the Seine estuary. On this site the maximum tidal range ranges between 1.25 and 3.5m respectively during neap and spring tide. The sampling strategy is based on continuous ADV acquisition at 4Hz coupled with turbidimeter and altimeter measurements (1 measurement every minute) in order to decipher sediment dynamics during one year. Our results indicate that sediment dynamics are controlled by river flow while medium term scale evolution is dependent on tidal range and short term dynamics on sea-vessels waves. 64% of boat passages generated significant sediment reworking (from few mm.min-1 to 3cm.min-1). This reworking rate is mainly controlled by two parameters: (i) water height on the site and (ii) vessels characteristics; in particular the distance between seabed and keel that generate a Bernoulli wave (with maximum amplitude of 0.6m). Simultaneous hydrodynamics and bed elevation measurements permit to quantify the impact of the boat generated wave. Measurements demonstrate that the sediment transport occurs during the Bernoulli wave (few mm up to 8cm). This mechanism induces mainly a long-shore transfer of particles over the interdal area. This study proves that the sediment transport generated by boat waves cannot be neglected in the Seine estuary case.
Impact of Sedation on Cognitive Function in Mechanically Ventilated Patients.
Porhomayon, Jahan; El-Solh, Ali A; Adlparvar, Ghazaleh; Jaoude, Philippe; Nader, Nader D
2016-02-01
The practice of sedation dosing strategy in mechanically ventilated patient has a profound effect on cognitive function. We conducted a comprehensive review of outcome of sedation on mental health function in critically ill patients on mechanical ventilation in the intensive care unit (ICU). We specifically evaluated current sedative dosing strategy and the development of delirium, post-traumatic stress disorders (PTSDs) and agitation. Based on this review, heavy dosing sedation strategy with benzodiazepines contributes to cognitive dysfunction. However, outcome for mental health dysfunction is mixed in regard to newer sedatives agents such as dexmedetomidine and propofol. Moreover, studies that examine the impact of sedatives for persistence of PTSD/delirium and its long-term cognitive and functional outcomes for post-ICU patients are frequently underpowered. Most studies suffer from low sample sizes and methodological variations. Therefore, larger randomized controlled trials are needed to properly assess the impact of sedation dosing strategy on cognitive function. PMID:26559680
Electromagnetic wave emitting products and "Kikoh" potentiate human leukocyte functions.
Niwa, Y; Iizawa, O; Ishimoto, K; Jiang, X; Kanoh, T
1993-09-01
Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called "Kikoh" in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4-14 microns). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of "Kikohshi" i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury. PMID:8406976
Electromagnetic wave emitting products and ``Kikoh'' potentiate human leukocyte functions
NASA Astrophysics Data System (ADS)
Niwa, Yukie; Iizawa, Osamu; Ishimoto, Koichi; Jiang, Xiaoxia; Kanoh, Tadashi
1993-09-01
Tourmaline (electric stone, a type of granite stone), common granite stone, ceramic disks, hot spring water and human palmar energy (called “Kikoh” in Japan and China), all which emit electromagnetic radiation in the far infrared region (wavelength 4 14 µm). These materials were thus examined for effects on human leukocyte activity and on lipid peroxidation of unsaturated fatty acids. It was revealed that these materials significantly increased intracellular calcium ion concentration, phagocytosis, and generation of reactive oxygen species in neutrophils, and the blastogenetic response of lymphocytes to mitogens. Chemotactic activity by neutrophils was also enhanced by exposure to tourmaline and the palm of “Kikohshi” i.e., a person who heals professionally by the laying on of hands. Despite the increase in reactive oxygen species generated by neutrophils, lipid peroxidation from unsaturated fatty acid was markedly inhibited by these four materials. The results suggest that materials emitting electromagnetic radiation in the far infrared range, which are widely used in Japan for cosmetic, therapeutic, and preservative purposes, appear capable of potentiating leukocyte functions without promoting oxidative injury.
NASA Astrophysics Data System (ADS)
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
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.
Modelling rock-avalanche induced impact waves: Sensitivity of the model chains to model parameters
NASA Astrophysics Data System (ADS)
Schaub, Yvonne; Huggel, Christian
2014-05-01
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.
NASA Astrophysics Data System (ADS)
Engel, Max; Brckner, Helmut; Messenzehl, Karoline; Frenzel, Peter; May, Simon Matthias; Scheffers, Anja; Scheffers, Sander; Wennrich, Volker; Kelletat, Dieter
2012-10-01
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.
Functional Impacts of Adult Literacy Programme on Rural Women
ERIC Educational Resources Information Center
Mbah, Blessing Akaraka
2015-01-01
This study assessed the functional impacts of adult literacy programme among rural women participants in Ishielu Local Government Area (LGA) of Ebonyi State, Nigeria. Descriptive survey design was used for the study. The population of the study was made up of 115 adult instructors and 2,408 adult learners giving a total of 2,623. The sample…
Adjustment of Born-Oppenheimer electronic wave functions to simplify close coupling calculations.
Buenker, Robert J; Liebermann, Heinz-Peter; Zhang, Yu; Wu, Yong; Yan, Lingling; Liu, Chunhua; Qu, Yizhi; Wang, Jianguo
2013-04-30
Technical problems connected with use of the Born-Oppenheimer clamped-nuclei approximation to generate electronic wave functions, potential energy surfaces (PES), and associated properties are discussed. A computational procedure for adjusting the phases of the wave functions, as well as their order when potential crossings occur, is presented which is based on the calculation of overlaps between sets of molecular orbitals and configuration interaction eigenfunctions obtained at neighboring nuclear conformations. This approach has significant advantages for theoretical treatments describing atomic collisions and photo-dissociation processes by means of ab initio PES, electronic transition moments, and nonadiabatic radial and rotational coupling matrix elements. It ensures that the electronic wave functions are continuous over the entire range of nuclear conformations considered, thereby greatly simplifying the process of obtaining the above quantities from the results of single-point Born-Oppenheimer calculations. The overlap results are also used to define a diabatic transformation of the wave functions obtained for conical intersections that greatly simplifies the computation of off-diagonal matrix elements by eliminating the need for complex phase factors. PMID:23345171
BLOCH model wave functions and pseudopotentials for all fractional Chern insulators.
Wu, Yang-Le; Regnault, N; Bernevig, B Andrei
2013-03-01
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 N(x)×N(y) 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. PMID:23521277
Frequency-Domain Green's Functions for Radar Waves in Heterogeneous 2.5D Media
Greens 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, ...
Muhlestein, Michael B; Gee, Kent L
2016-02-01
An exact formulation for the evolution of the probability density function of the time derivative of a waveform (slope density) propagating according to the one-dimensional inviscid Burgers equation is given. The formulation relies on the implicit Earnshaw solution and therefore is only valid prior to shock formation. As explicit examples, the slope density evolution of an initially sinusoidal plane wave, initially Gaussian-distributed planar noise, and an initially triangular wave are presented. The triangular wave is used to examine weak-shock limits without violating the theoretical assumptions. It is also shown that the moments of the slope density function as a function of distance may be written as an expansion in terms of the moments of the source slope density function. From this expansion, approximate expressions are presented for the above cases as well as a specific non-Gaussian noise case intended to mimic features of jet noise. Finally, analytical predictions of the propagation of initially Gaussian-distributed noise are compared favorably with plane-wave tube measurements. PMID:26936575
Alternative Form of the Hydrogenic Wave Functions for an Extended, Uniformly Charged Nucleus.
ERIC Educational Resources Information Center
Ley-Koo, E.; And Others
1980-01-01
Presented are forms of harmonic oscillator attraction and Coulomb wave functions which can be explicitly constructed and which lead to numerical results for the energy eigenvalues and eigenfunctions of the atomic system. The Schrodinger equation and its solution and specific cases of muonic atoms illustrating numerical calculations are included.…
Channel-Coupling Contribution to the Widths of Decay Nuclear States and to Their Wave Functions
Kadmensky, S.G.
2004-12-01
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.
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...
Reply to ``Comment on `Fine-structure and analytical quantum-defect wave functions' ''
NASA Astrophysics Data System (ADS)
Kostelecký, V. Alan; Nieto, Michael Martin; Truax, D. Rodney
1990-02-01
The preceding Comment by Goodfriend [Phys. Rev. A 41, 1730 (1990)] contains three criticisms of our model for analytical quantum-defect wave functions vis-á-vis the atomic Fues potential of Simons [J. Phys. Chem. 55, 756 (1971)]. We rebut the first two criticisms explicitly. This makes the third criticism moot. We stand by our results.
The Use of the Information Wave Function in a Drift Dependent Option Price: A Simple Example
Haven, Emmanuel
2009-03-10
This paper briefly describes how a drift-dependent option price is obtained, following the work of Tan. We briefly argue how the information wave function concept, which has now been used in various financial settings, can be used in this type of option price.
Alternative Form of the Hydrogenic Wave Functions for an Extended, Uniformly Charged Nucleus.
ERIC Educational Resources Information Center
Ley-Koo, E.; And Others
1980-01-01
Presented are forms of harmonic oscillator attraction and Coulomb wave functions which can be explicitly constructed and which lead to numerical results for the energy eigenvalues and eigenfunctions of the atomic system. The Schrodinger equation and its solution and specific cases of muonic atoms illustrating numerical calculations are included.
Observations of the directional distribution of the wind energy input function over swell waves
NASA Astrophysics Data System (ADS)
Shabani, Behnam; Babanin, Alex V.; Baldock, Tom E.
2016-02-01
Field measurements of wind stress over shallow water swell traveling in different directions relative to the wind are presented. The directional distribution of the measured stresses is used to confirm the previously proposed but unverified directional distribution of the wind energy input function. The observed wind energy input function is found to follow a much narrower distribution (β∝cos3.6θ) than the Plant (1982) cosine distribution. The observation of negative stress angles at large wind-wave angles, however, indicates that the onset of negative wind shearing occurs at about θ≈ 50°, and supports the use of the Snyder et al. (1981) directional distribution. Taking into account the reverse momentum transfer from swell to the wind, Snyder's proposed parameterization is found to perform exceptionally well in explaining the observed narrow directional distribution of the wind energy input function, and predicting the wind drag coefficients. The empirical coefficient (ɛ) in Snyder's parameterization is hypothesised to be a function of the wave shape parameter, with ɛ value increasing as the wave shape changes between sinusoidal, sawtooth, and sharp-crested shoaling waves.
Three-Dimensional Visualization of Wave Functions for Rotating Molecule: Plot of Spherical Harmonics
ERIC Educational Resources Information Center
Nagaoka, Shin-ichi; Teramae, Hiroyuki; Nagashima, Umpei
2013-01-01
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
Three-Dimensional Visualization of Wave Functions for Rotating Molecule: Plot of Spherical Harmonics
ERIC Educational Resources Information Center
Nagaoka, Shin-ichi; Teramae, Hiroyuki; Nagashima, Umpei
2013-01-01
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…
Frequency-Domain Green's Functions for Radar Waves in Heterogeneous 2.5D Media
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, ...
McAleavey, Stephen A
2014-05-01
Shear wave induced phase encoding (SWIPE) imaging generates ultrasound backscatter images of tissue-like elastic materials by using traveling shear waves to encode the lateral position of the scatters in the phase of the received echo. In contrast to conventional ultrasound B-scan imaging, SWIPE offers the potential advantages of image formation without beam focusing or steering from a single transducer element, lateral resolution independent of aperture size, and the potential to achieve relatively high lateral resolution with low frequency ultrasound. Here a Fourier series description of the phase modulated echo signal is developed, demonstrating that echo harmonics at multiples of the shear wave frequency reveal target k-space data at identical multiples of the shear wavenumber. Modulation transfer functions of SWIPE imaging systems are calculated for maximum shear wave acceleration and maximum shear constraints, and compared with a conventionally focused aperture. The relative signal-to-noise ratio of the SWIPE method versus a conventionally focused aperture is found through these calculations. Reconstructions of wire targets in a gelatin phantom using 1 and 3.5 MHz ultrasound and a cylindrical shear wave source are presented, generated from the fundamental and second harmonic of the shear wave modulation frequency, demonstrating weak dependence of lateral resolution with ultrasound frequency. PMID:24815265
Comparing thermal wave function methods for multi-configuration time-dependent Hartree simulations
Lorenz, U.; Saalfrank, P.
2014-01-28
We compare two methods for creating stochastic temperature wave functions that can be used for Multi-Configuration Time-Dependent Hartree (MCTDH) simulations. In the first method, the MCTDH coefficients are chosen randomly, while the other method uses a single Hartree product of random single-particle functions (SPFs). We find that using random SPFs dramatically improves convergence for a model system for surface sticking.
ERIC Educational Resources Information Center
Kalbfleisch, M. Layne; Loughan, Ashlee R.
2012-01-01
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…
NASA Astrophysics Data System (ADS)
Menendez, Melisa; Perez, Jorge; Cid, Alba; Castanedo, Sonia; Losada, Inigo; Medina, Raul; Mendez, Fernando
2015-04-01
Despite their outstanding relevance in coastal processes, a study of the sea surface dynamics due to atmospheric wind and pressure variations are rather limited in comparison with the mean sea level rise. Data of waves and surges along the European region are scarce and in-homogeneous, not only in terms of spatial coverage but also in terms of temporal coverage. This study presents two databases focused on a historical reconstruction of: (i) the wind-generated waves (GOW) and (ii) the meteorological sea level component (GOS). The GOW and GOS datasets cover the whole European coast (North Atlantic, North Sea, Baltic Sea, Mediterranean Sea and Black Sea) at high-spatial resolution from 1979 to present. The meteorological sea level component (storm surge) has been generated by the Regional Ocean Model System (ROMS). To take into account non-linear interactions between tides and surges, both dynamics were simulated jointly. Final results of meteorological component of sea level were obtained by subtracting the astronomical tide from the simulated sea surface. The model was set-up for Europe using an orthogonal grid, with a horizontal resolution ranging between 3.5 to 11 km. A spatial domain of approximately 5 km was used for the Black Sea. Local coastal waves can be the integrated result of the ocean surface over a large region of influence. GOW-Europe is designed from a multigrid approach based on the overlapping of two-way nested domains. The coarser spatial resolution along the European coast of GOW is 15 km. The generation and propagation of the sea surface waves of GOW-Europe are simulated with the model WAVEWATCH III v4.18. Effects of non-linear wave-wave interactions, whitecapping and depth-induced refraction are considered in the propagation model. In order to validate GOW and GOS over Europe with available observations, an exhaustive comparison with in-situ and remote measurements was developed. In-situ buoys and tide-gauges are used to compare hourly time series of surge sea level component and waves (significant wave height, period and direction) at coastal locations. Altimeter observations are also considered for a spatial validation of surge and wave heights. Results obtained from this validation process show a general good agreement with observations for the European region. Finally, the hourly time series of surge and wave climate along the European coast grid-points are analyzed. Historical changes in the waves and storm surge provide a useful information for coastal impact studies since coastal flooding, beach erosion, coastal structures and physical damages in ecosystems can be affected by long-term changes in wave climate and sea levels. Reguero, B. G., Menéndez, M., Méndez, F. J. Mínguez, R. Losada, I. J. (2012). A Global Ocean Wave (GOW) calibrated reanalysis from 1948 onwards. Coastal Engineering, 65, 38-55. Cid, A., Castanedo, S., Abascal, A. J., Menéndez, M., & Medina, R. (2014). A high resolution hindcast of the meteorological sea level component for Southern Europe: the GOS dataset. Climate Dynamics, 1-18.
Cuypers, Yannis; Vinçon-Leite, Brigitte; Groleau, Alexis; Tassin, Bruno; Humbert, Jean-François
2011-01-01
The vertical and horizontal distribution of the cyanobacterium, Planktothrix rubescens, was studied in a deep alpine lake (Lac du Bourget) in a 2-year monitoring program with 11 sampling points, and a 24-h survey at one sampling station. This species is known to proliferate in the metalimnic layer of numerous deep mesotrophic lakes in temperate areas, and also to produce hepatotoxins. When looking at the distribution of P. rubescens at the scale of the entire lake, we found large variations (up to 10 m) in the depth of the biomass peak in the water column. These variations were closely correlated to isotherm displacements. We also found significant variations in the distribution of the cyanobacterial biomass in the northern and southern parts of the lake. We used a physical modeling approach to demonstrate that two internal wave modes can explain these variations. Internal waves are generated by wind events, but can still be detected several days after the end of these events. Finally, our 24-h survey at one sampling point demonstrated that the V1H1 sinusoidal motion could evolve into nonlinear fronts. All these findings show that internal waves have a major impact on the distribution of P. rubescens proliferating in the metalimnic layer of a deep lake, and that this process could influence the growth of this species by a direct impact on light availability. PMID:21085197
Wave Impact on a Wall: Comparison of Experiments with Similarity Solutions
NASA Astrophysics Data System (ADS)
Wang, A.; Duncan, J. H.; Lathrop, D. P.
2014-11-01
The impact of a steep water wave on a fixed partially submerged cube is studied with experiments and theory. The temporal evolution of the water surface profile upstream of the front face of the cube in its center plane is measured with a cinematic laser-induced fluorescence technique using frame rates up to 4,500 Hz. For a small range of cube positions, the surface profiles are found to form a nearly circular arc with upward curvature between the front face of the cube and a point just downstream of the wave crest. As the crest approaches the cube, the effective radius of this portion of the profile decreases rapidly. At the same time, the portion of the profile that is upstream of the crest approaches a straight line with a downward slope of about 15°. As the wave impact continues, the circular arc shrinks to zero radius with very high acceleration and a sudden transition to a high-speed vertical jet occurs. This flow singularity is modeled with a power-law scaling in time, which is used to create a time-independent system of equations of motion. The scaled governing equations are solved numerically and the similarly scaled measured free surface shapes, are favorably compared with the solutions. The support of the Office of Naval Research is gratefully acknowledged.
NASA Astrophysics Data System (ADS)
Goldstein, Sheldon; Lebowitz, Joel L.; Mastrodonato, Christian; Tumulka, Roderich; Zanghì, Nino
2016-03-01
A quantum system (with Hilbert space {H}1) entangled with its environment (with Hilbert space {H}2) is usually not attributed to a wave function but only to a reduced density matrix {ρ1}. Nevertheless, there is a precise way of attributing to it a random wave function {ψ1}, called its conditional wave function, whose probability distribution {μ1} depends on the entangled wave function {ψ in H1 ⊗ H2} in the Hilbert space of system and environment together. It also depends on a choice of orthonormal basis of H2 but in relevant cases, as we show, not very much. We prove several universality (or typicality) results about {μ1}, e.g., that if the environment is sufficiently large then for every orthonormal basis of H2, most entangled states {ψ} with given reduced density matrix {ρ1} are such that {μ1} is close to one of the so-called GAP (Gaussian adjusted projected) measures, {GAP(ρ1)}. We also show that, for most entangled states {ψ} from a microcanonical subspace (spanned by the eigenvectors of the Hamiltonian with energies in a narrow interval {[E, E+ δ E]}) and most orthonormal bases of H2, {μ1} is close to {GAP({tr}2 ρ_{mc})} with {ρ_{mc}} the normalized projection to the microcanonical subspace. In particular, if the coupling between the system and the environment is weak, then {μ1} is close to {GAP(ρ_β)} with {ρ_β} the canonical density matrix on H1 at inverse temperature {β=β(E)}. This provides the mathematical justification of our claim in Goldstein et al. (J Stat Phys 125: 1193-1221, 2006) that GAP measures describe the thermal equilibrium distribution of the wave function.
Pedemonte, Marisa; Testa, Martn; Daz, Marcela; Surez-Bagnasco, Diego
2014-09-01
Based on the knowledge that sensory processing continues during sleep and that a relationship exists between sleep and learning, a new strategy for treatment of idiopathic subjective tinnitus, consisted of customized sound stimulation presented during sleep, was tested. It has been previously shown that this treatment induces a sustained decrease in tinnitus intensity; however, its effect on brain activity has not yet been studied. In this work, we compared the impact of sound stimulation in tinnitus patients in the different sleep stages. Ten patients with idiopathic tinnitus were treated with sound stimulation mimicking tinnitus during sleep. Power spectra and intra- and inter-hemispheric coherence of electroencephalographic waves from frontal and temporal electrodes were measured with and without sound stimulation for each sleep stage (stages N2 with sleep spindles; N3 with slow wave sleep and REM sleep with Rapid Eye Movements). The main results found were that the largest number of changes, considering both the power spectrum and wave?s coherence, occurred in stages N2 and N3. The delta and theta bands were the most changed, with important changes also in coherence of spindles during N2. All changes were more frequent in temporal areas. The differences between the two hemispheres do not depend, at least exclusively, on the side where the tinnitus is perceived and, hence, of the stimulated side. These results demonstrate that sound stimulation during sleep in tinnitus patients? influences brain activity and open an avenue for investigating the mechanism underlying tinnitus and its treatment. PMID:26483919
The inertia-gravity waves caused by the impact of shoemaker-levy 9 with jupiter
NASA Astrophysics Data System (ADS)
Bao, Gang; Chen, Dao-han; Ma, Yue-hua
2005-04-01
After the collision of Comet Shoemaker-Levy 9 (SL9) with Jupiter, some ring structures were observed propagating outwards at a constant speed (∼450 m/s) on the Jovian surface. These are thought to be linear waves caused by the collision. A linear model of the collision is presented, in which the Jovian atmosphere is considered as an irrotational, inviscid, stratified and incompressible fluid layer moving at a speed of U = b + az. We take an initial impulsive pressure p(r; 0) as the initial condition and solve the fluid dynamics equations for inertia-gravity waves. It is found that most part of the perturbation energy is used to produce internal waves when Jovian atmosphere moves at a constant speed (U = Uo (∼170 m/s)). A relation between the impact depth H and the horizontal phase speed vp is deduced. Finally, the inertia-gravity waves are discussed for the case U = b + az and it is found that the perturbation energy is then not divided equally between kinetic energy and potential energy because of the effect of a shear.
The impact of consecutive freshwater trimix dives at altitude on human cardiovascular function.
Lozo, Mislav; Madden, Dennis; Gunjaca, Grgo; Ljubkovic, Marko; Marinovic, Jasna; Dujic, Zeljko
2015-03-01
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
Density Functional Study of the Transport and Electronic Properties of Waved Graphene Nanoribbons
NASA Astrophysics Data System (ADS)
Hammouri, Mahmoud; Vasiliev, Igor
2015-03-01
First principles ab initio calculations are employed to study the electronic and transport properties of waved graphene nanoribbons. Our calculations are performed using the SIESTA and TRANSIESTA density functional electronic structure codes. We find that the band gaps of graphene nanoribbons with symmetrical edges change very slightly with the increasing compression, whereas the band gaps of nanoribbons with asymmetrical edges change significantly. The computed IV-characteristics of the waved graphene nanoribbons with different compression ratios reveal the effect of compression on the transport properties of graphene nanoribbons. Supported by NMSU GREG Award and by NSF CHE-1112388.
Quantum diffusion wave-function approach to two-dimensional vibronic spectroscopy
Wehner, Johannes; Falge, Mirjam; Engel, Volker; Strunz, Walter T.
2014-10-07
We apply the quantum diffusion wavefunction approach to calculate vibronic two-dimensional (2D) spectra. As an example, we use a system consisting of two electronic states with harmonic oscillator potentials which are coupled to a bath and interact with three time-delayed laser pulses. The first- and second-order perturbative wave functions which enter into the expression for the third-order polarization are determined for a sufficient number of stochastic runs. The wave-packet approach, besides being an alternative technique to calculate the spectra, offers an intuitive insight into the dissipation dynamics and its relation to the 2D vibronic spectra.
Quantum diffusion wave-function approach to two-dimensional vibronic spectroscopy.
Wehner, Johannes; Falge, Mirjam; Strunz, Walter T; Engel, Volker
2014-10-01
We apply the quantum diffusion wavefunction approach to calculate vibronic two-dimensional (2D) spectra. As an example, we use a system consisting of two electronic states with harmonic oscillator potentials which are coupled to a bath and interact with three time-delayed laser pulses. The first- and second-order perturbative wave functions which enter into the expression for the third-order polarization are determined for a sufficient number of stochastic runs. The wave-packet approach, besides being an alternative technique to calculate the spectra, offers an intuitive insight into the dissipation dynamics and its relation to the 2D vibronic spectra. PMID:25296805
Temporomandibular joint disorders' impact on pain, function, and disability.
Chantaracherd, P; John, M T; Hodges, J S; Schiffman, E L
2015-03-01
The aim of this study was to determine the association between more advanced stages of temporomandibular joint (TMJ) intra-articular disorders ("TMJ intra-articular status"), representing a transition from normal joint structure to TMJ disc displacement with and without reduction (DDwR and DDwoR) to degenerative joint disease (DJD), and patient-reported outcomes of jaw pain, function, and disability ("TMD impact"). This cross-sectional study included 614 cases from the RDC/TMD Validation Project with at least one temporomandibular disorder (TMD) diagnosis. TMJ intra-articular status was determined by 3 blinded, calibrated radiologists using magnetic resonance imaging and computed tomography as one of normal joint structure, DDwR, DDwoR, or DJD, representing the subject's most advanced TMJ diagnosis. TMD impact was conceptualized as a latent variable consisting of 1) pain intensity (Characteristic Pain Index from the Graded Chronic Pain Scale [GCPS]), 2) jaw function (Jaw Functional Limitation Scale), and 3) disability (Disability Points from GCPS). A structural equation model estimated the association of TMJ intra-articular status with the latent measure TMD impact as a correlation coefficient in all TMD cases (n = 614) and in cases with a TMD pain diagnosis (n = 500). The correlations between TMJ intra-articular status and TMD impact were 0.05 (95% confidence interval [CI], -0.04 to 0.13) for all TMD cases and 0.07 (95% CI, -0.04 to 0.17) for cases with a pain diagnosis, which are neither statistically significant nor clinically relevant. Conceptualizing worsening of TMJ intra-articular disorders as 4 stages and characterizing impact from TMD as a composite of jaw pain, function, and disability, this cross-sectional study found no clinically significant association. Models of TMJ intra-articular status other than ours (normal structure → DDwR → DDwoR → DJD) should be explored. PMID:25572112
Preliminary Results for Crustal Structure in Southeastern Africa from P-wave Receiver Functions
NASA Astrophysics Data System (ADS)
Kachingwe, M.; Nyblade, A.; Mulibo, G. D.; Mulowezi, A.; Kunkuta, E.; De Magalhes, V.; Wiens, D. A.; Wysession, M. E.; Julia, J.
2013-12-01
The crustal structure of southeastern Africa is investigated by modeling P-wave receiver functions using H-k stacking and joint inversion methods. P-wave receiver functions are analyzed for 29 broadband seismic stations in Zambia, Malawi and Mozambique. Estimates for the Moho depth and Poisson's ratio are determined from H-k stacking, and estimates for the shear wave velocity are determined by the joint inversion of receiver functions and surface wave dispersion. Preliminary results show that Moho depths beneath southeastern Africa range from 32 km to 51 km. Thicker crust is found in Proterozoic terrains, such as the Irumide Belt, while thinner crust is found in reworked Archean terrains, such as the Bangweulu Block. These results are consistent with previous studies and global averages for Precambrian terrains. The preliminary results also show a range of Poisson's ratios from 0.2 to 0.3. These new results for southeastern Africa are being combined with similar results from elsewhere in eastern and southern Africa to improve our understanding of African crustal structure.
Preliminary Results for Crustal Structure in Southeastern Africa from P-wave Receiver Functions
NASA Astrophysics Data System (ADS)
Kachingwe, M.; Nyblade, A.; Mulibo, G.; Mulowezi, A.; Kunkuta, E.; De Magalhes, V.; Wysession, M. E.; Wiens, D. A.; Julia, J.
2012-12-01
The crustal structure of southeastern Africa is investigated by modeling P-wave receiver functions using H-k stacking and joint inversion methods. P-wave receiver functions are analyzed for 29 broadband seismic stations in Zambia, Malawi and Mozambique. Estimates for the Moho depth and Poisson's ratio are determined from H-k stacking, and estimates for the shear wave velocity are determined by the joint inversion of receiver functions and surface wave dispersion. Preliminary results show that Moho depths beneath southeastern Africa range from 32 km to 51 km. Thicker crust is found in Proterozoic terrains, such as the Irumide Belt, while thinner crust is found in reworked Archean terrains, such as the Bangweulu Block. These results are consistent with previous studies and global averages for Precambrian terrains. The preliminary results also show a range of Poisson's ratios from 0.2 to 0.3. These new results for southeastern Africa are being combined with similar results from elsewhere in eastern and southern Africa to improve our understanding of African crustal structure.
Short and Long Wave Radiative Forcing from Desert Dust and Impacts on Weather and Climate
NASA Astrophysics Data System (ADS)
Kallos, G.; Spyrou, C.; Mitsakou, C.
2009-04-01
The presence of desert dust in the atmosphere has considerable impacts on radiative transfer, clouds and precipitation. Desert dust is a considerable climate modifier. The impacts of desert dust to land and marine ecosystems are considerable as well in humans. Modeling tools have been developed for studying the dust cycle in both global and regional scales. The uncertainties associated with the dust production, transport and deposition processes are still high for various reasons. Most of them are associated with the surface properties and dust production as well as with the radiative forcing parameterization. Modeling the impacts on radiation and cloud is a complicated task that is either oversimplified or absent in most of the dust models. Radiative transfer corrections due to the presence of dust particles for the incoming solar radiation can be applied (shading effects) by utilizing look up tables in the calculation of Aerosol Optical Depth (AOD). The impacts of dust on long wave radiation transfer are more complicated. A new version of the SKIRON/Dust modeling system incorporates the Rapid Radiative Transfer Model - RRTM for both short and long wave radiation. The new radiative transfer scheme has many properties that allow the partitioning of both short and long wave radiation according to the dust concentration and size distribution. In this presentation we discuss the new model characteristics and especially the dust radiative properties as described by both: lookup tables and empirical formulation as well as the new approach by utilizing RRTM. Several cases with dust outbreaks in the Mediterranean and Europe have been analyzed. Heating rates of 2-10 degrees K/day (or even higher in cases of a strong episode) have been calulated within the dust layer. The model results are compared with soundings, lidar and AERONET observations. As it was found, the dust cloud has as a result the surface cooling of 50-80 Wm-2 in remote locations. Near the source areas is double or even triple to these amounts. The long wave radiation forcing below and above the dust cloud is considerable and results in mid and low tropospheric warming that has as impact the stabilization of the atmosphere and reduction of precipitation.
Wave propagation analysis of edge cracked circular beams under impact force.
Akbaş, Şeref Doğuşcan
2014-01-01
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
Wave Propagation Analysis of Edge Cracked Circular Beams under Impact Force
Akbaş, Şeref Doğuşcan
2014-01-01
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
Modeling the ionospheric impact of tsunami-driven gravity waves with SAMI3: Conjugate effects
NASA Astrophysics Data System (ADS)
Huba, J. D.; Drob, D. P.; Wu, T.-W.; Makela, J. J.
2015-07-01
The Naval Research Laboratory first-principles ionosphere model SAMI3 is used to study the ionospheric effects associated with tsunami-driven gravity waves. Specifically, the Tohoku-Oki tsunami of 11 March 2011 is modeled. It is shown that gravity wave-induced variations in the neutral wind lead to plasma velocity variations both perpendicular and parallel to the geomagnetic field. Moreover, the electric field induced by the neutral wind perturbations can map to the conjugate hemisphere. Thus, electron density variations can be generated in both hemispheres which impact the total electron content (TEC) and 6300 Šairglow emission. It is found that the TEC exhibits variations of ≲ ±0.1 total electron content unit (1 TECU = 1016 el m-2) and the 6300 Šairglow emission variation is up to ˜±2.5% relative to the unperturbed background airglow.
How child's play impacts executive function--related behaviors.
Shaheen, Sandra
2014-01-01
Executive functions refer to an array of organizing and self-regulating behaviors often associated with maturation of the prefrontal cortex. In fact, young children with rudimentary neurodevelopment of the prefrontal cortex develop ways to inhibit impulses and regulate behavior from a very early age. Can executive functioning be impacted by intervention, practice, or training? What interventions impact development of executive function in childhood, and how can these be studied? Several programs are reviewed that propose to positively impact executive/self-regulation skills. Evidence-based programs are contrasted with popular programs that have little empirical basis but have apparent wide acceptance by educators and families. As self-regulation has critical implications for later school and life success, interventions may well attenuate the negative consequences of attention-deficit hyperactivity disorder, brain injury, and social stressors. Programs with active play components may be more successful in eliciting improved executive function (defined here as self-regulation) because of the importance of motor learning early on and because of the social motivation aspects of learning. Caution is advised in the recommendation of programs where there is little empirical basis to support program claims. Carefully planned outcome studies can help bring the most effective components of programs to the mainstream. PMID:25010084
Critical wave functions and a Cantor-set spectrum of a one-dimensional quasicrystal model
NASA Astrophysics Data System (ADS)
Kohmoto, Mahito; Sutherland, Bill; Tang, Chao
1987-01-01
The electronic properties of a tight-binding model which possesses two types of hopping matrix element (or on-site energy) arranged in a Fibonacci sequence are studied. The wave functions are either self-similar (fractal) or chaotic and show ``critical'' (or ``exotic'') behavior. Scaling analysis for the self-similar wave functions at the center of the band and also at the edge of the band is performed. The energy spectrum is a Cantor set with zero Lebesque measure. The density of states is singularly concentrated with an index αE which takes a value in the range [αminE,αmaxE]. The fractal dimensions f(αE) of these singularities in the Cantor set are calculated. This function f(αE) represents the global scaling properties of the Cantor-set spectrum.
Dust heating by Alfvén waves using non-Maxwellian distribution function
Zubia, K.; Shah, H. A.; Yoon, P. H.
2015-08-15
Quasilinear theory is employed in order to evaluate the resonant heating rate by Alfvén waves, of multiple species dust particles in a hot, collisionless, and magnetized plasma, with the underlying assumption that the dust velocity distribution function can be modeled by a generalized (r, q) distribution function. The kinetic linear dispersion relation for the electromagnetic dust cyclotron Alfvén waves is derived, and the dependence of the heating rate on the magnetic field, mass, and density of the dust species is subsequently investigated. The heating rate and its dependence on the spectral indices r and q of the distribution function are also investigated. It is found that the heating is sensitive to negative value of spectral index r.
On a special function used in the description of electromagnetic surface waves
NASA Astrophysics Data System (ADS)
Bezrukova, E. G.; Rudenchik, E. A.
2011-03-01
The tangential component of the electric field of a surface wave at any distance from the transmitting antenna lying in the interface plane of two homogeneous media can be represented in terms of a function of two complex variables Ŵ( q,ξ) for arbitrary parameters of the interface. In this paper, representations of the function Ŵ( q,ξ) in the form of series are given that allow one to quickly calculate the values of Ŵ( q,ξ) and to investigate the analytic properties of this function. The dependence of the field of the surface wave on time is determined using the inverse Laplace transform, where the path of integration is chosen in such a way that the integrand rapidly decreases at infinity, which drastically improves the computation speed compared with the method based on the Fourier transform.
Frequency-domain Green's functions for radar waves in heterogeneous 2.5D media
Ellefsen, K.J.; Croize, D.; Mazzella, A.T.; McKenna, J.R.
2009-01-01
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.
Comparative study of different SPH schemes on simulating violent water wave impact flows
NASA Astrophysics Data System (ADS)
Zheng, Xing; Ma, Qing-wei; Duan, Wen-yang
2014-12-01
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.
In vivo transmission of impact shock waves in the distal forelimb of the horse.
Gustås, P; Johnston, C; Roepstorff, L; Drevemo, S
2001-04-01
There is a high prevalence of lameness among Standardbred trotters, most commonly caused by noninfectious joint diseases, mainly related to training and competition. In this context, impact-related shock waves transmitted through the skeleton and joints have been proposed to be one important factor in the development of osteoarthritis. The aim of the present study was to investigate the characteristic pattern of the events immediately following first contact, with a focus on the in vivo transmission of impact shock waves in the distal forelimb. Two horses were trotted by hand over a force plate. Recordings of 3-D kinematics of the distal forelimb were carried out by use of a 240 Hz video system. Tri-axial accelerometer data were collected from a bone-mounted accelerometer on the midlateral side of the third metacarpal bone (McIII) and from another accelerometer attached to the lateral side of the hoof. Force plate and accelerometer data were sampled at 4.8 kHz using a 16-bit A/D-converter, synchronised with the kinematic data. The results indicate that the time lapse of the horizontal retardation of the hoof is an important factor in the attenuation of the impact. A shorter period of hoof braking showed higher amplitudes in the longitudinal retardation of McIII and a more rapid oscillation. This makes all parameters that affect the horizontal hoof braking potentially important to the orthopaedic health of the horse. PMID:11721549
Global Propagation of Gravity Waves Generated with the Whole Atmosphere Transfer Function Model
NASA Astrophysics Data System (ADS)
Mayr, H. G.; Talaat, E. R.; Wolven, B. C.
2012-12-01
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].
Multi-spectral Metasurface for Different Functional Control of Reflection Waves
NASA Astrophysics Data System (ADS)
Huang, Cheng; Pan, Wenbo; Ma, Xiaoliang; Luo, Xiangang
2016-03-01
Metasurface have recently generated much interest due to its strong manipulation of electromagnetic wave and its easy fabrication compared to bulky metamaterial. Here, we propose the design of a multi-spectral metasurface that can achieve beam deflection and broadband diffusion simultaneously at two different frequency bands. The metasurface is composed of two-layered metallic patterns backed by a metallic ground plane. The top-layer metasurface utilizes the cross-line structures with two different dimensions for producing 0 and π reflection phase response, while the bottom-layer metasurface is realized by a topological morphing of the I-shaped patterns for creating the gradient phase distribution. The whole metasurface is demonstrated to independently control the reflected waves to realize different functions at two bands when illuminated by a normal linear-polarized wave. Both simulation and experimental results show that the beam deflection is achieved at K-band with broadband diffusion at X-Ku band.
Delta shock waves with Dirac delta function in both components for systems of conservation laws
NASA Astrophysics Data System (ADS)
Yang, Hanchun; Zhang, Yanyan
2014-12-01
We study a class of non-strictly and weakly hyperbolic systems of conservation laws which contain the equations of geometrical optics as a prototype. The Riemann problems are constructively solved. The Riemann solutions include two kinds of interesting structures. One involves a cavitation where both state variables tend to zero forming a singularity, the other is a delta shock wave in which both state variables contain Dirac delta function simultaneously. The generalized Rankine-Hugoniot relation and entropy condition are proposed to solve the delta shock wave. Moreover, with the limiting viscosity approach, we show all of the existence, uniqueness and stability of solution involving the delta shock wave. The generalized Rankine-Hugoniot relation is also confirmed. Then our theory is successfully applied to two typical systems including the geometric optics equations. Finally, we present the numerical results coinciding with the theoretical analysis.
Multi-spectral Metasurface for Different Functional Control of Reflection Waves
Huang, Cheng; Pan, Wenbo; Ma, Xiaoliang; Luo, Xiangang
2016-01-01
Metasurface have recently generated much interest due to its strong manipulation of electromagnetic wave and its easy fabrication compared to bulky metamaterial. Here, we propose the design of a multi-spectral metasurface that can achieve beam deflection and broadband diffusion simultaneously at two different frequency bands. The metasurface is composed of two-layered metallic patterns backed by a metallic ground plane. The top-layer metasurface utilizes the cross-line structures with two different dimensions for producing 0 and π reflection phase response, while the bottom-layer metasurface is realized by a topological morphing of the I-shaped patterns for creating the gradient phase distribution. The whole metasurface is demonstrated to independently control the reflected waves to realize different functions at two bands when illuminated by a normal linear-polarized wave. Both simulation and experimental results show that the beam deflection is achieved at K-band with broadband diffusion at X-Ku band. PMID:27001206
A Proton-cyclotron Wave Storm Generated by Unstable Proton Distribution Functions in the Solar Wind
NASA Astrophysics Data System (ADS)
Wicks, R. T.; Alexander, R. L.; Stevens, M.; Wilson, L. B., III; Moya, P. S.; Viñas, A.; Jian, L. K.; Roberts, D. A.; O'Modhrain, S.; Gilbert, J. A.; Zurbuchen, T. H.
2016-03-01
We use audification of 0.092 s cadence magnetometer data from the Wind spacecraft to identify waves with amplitudes \\gt 0.1 nT near the ion gyrofrequency (˜0.1 Hz) with duration longer than 1 hr during 2008. We present one of the most common types of event for a case study and find it to be a proton-cyclotron wave storm, coinciding with highly radial magnetic field and a suprathermal proton beam close in density to the core distribution itself. Using linear Vlasov analysis, we conclude that the long-duration, large-amplitude waves are generated by the instability of the proton distribution function. The origin of the beam is unknown, but the radial field period is found in the trailing edge of a fast solar wind stream and resembles other events thought to be caused by magnetic field footpoint motion or interchange reconnection between coronal holes and closed field lines in the corona.
Multi-spectral Metasurface for Different Functional Control of Reflection Waves.
Huang, Cheng; Pan, Wenbo; Ma, Xiaoliang; Luo, Xiangang
2016-01-01
Metasurface have recently generated much interest due to its strong manipulation of electromagnetic wave and its easy fabrication compared to bulky metamaterial. Here, we propose the design of a multi-spectral metasurface that can achieve beam deflection and broadband diffusion simultaneously at two different frequency bands. The metasurface is composed of two-layered metallic patterns backed by a metallic ground plane. The top-layer metasurface utilizes the cross-line structures with two different dimensions for producing 0 and π reflection phase response, while the bottom-layer metasurface is realized by a topological morphing of the I-shaped patterns for creating the gradient phase distribution. The whole metasurface is demonstrated to independently control the reflected waves to realize different functions at two bands when illuminated by a normal linear-polarized wave. Both simulation and experimental results show that the beam deflection is achieved at K-band with broadband diffusion at X-Ku band. PMID:27001206
ULF wave activity in high-speed streams of the solar wind: Impact on the magnetosphere
NASA Astrophysics Data System (ADS)
Potapov, A. S.
2013-10-01
recent years, the study of solar-magnetospheric interaction has increasingly been focusing on wave phenomena and the role of turbulence in the processes of energy and momentum transfer from the Sun to the Earth's magnetosphere. Here we consider one aspect of the problem — the impact of wave patterns associated with high-speed solar wind streams (HSSs) on the variable geomagnetic field and the trapped radiation. The superposed epoch method was chosen as our research technique. We use observations of the solar wind plasma and the interplanetary magnetic field at libration point L1, as well as measurements of electron fluxes at geostationary orbit and of geomagnetic pulsations on ground. Data from 31 corotating interaction regions (CIR), their sources being coronal holes on the Sun, and 13 streams from coronal mass ejections (CME) were processed. The focus is on the regime of ultra-low frequency (ULF) waves in high-speed flows and ULF fluctuations in the magnetosphere. A significant difference has been revealed between the wave activity characteristics of the two HSS types in the solar wind and on the earth. Irregular pulses are typical for coronal mass ejections and wave-like conditions are common for CIRs. For the latter, the temporal profile of the normalized ULF amplitude in the solar wind is similar to the pulsation amplitude profile on the ground. We also found that a high level of ULF activity in the magnetosphere during CIR intervals is favorable to 2 MeV electron flux enhancement, but does not affect the flux of less energetic electrons.
Mehrkash, Milad; Azhari, Mojtaba; Mirdamadi, Hamid Reza
2014-01-01
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
FRACTALS WITH POINT IMPACT IN FUNCTIONAL LINEAR REGRESSION
McKeague, Ian W.; Sen, Bodhisattva
2013-01-01
This paper develops a point impact linear regression model in which the trajectory of a continuous stochastic process, when evaluated at a “sensitive time point”, is associated with a scalar response. The proposed model complements and is more interpretable than the functional linear regression approach that has become popular in recent years. The trajectories are assumed to have fractal (self-similar) properties in common with a fractional Brownian motion with an unknown Hurst exponent. Bootstrap confidence intervals based on the least-squares estimator of the sensitive time point are developed. Misspecification of the point impact model by a functional linear model is also investigated. Non-Gaussian limit distributions and rates of convergence determined by the Hurst exponent play an important role. PMID:23785219
NASA Astrophysics Data System (ADS)
Peng, Liang-You; Gong, Qihuang
2010-12-01
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.
Monti, J M; Tachino, C A; Hanssen, J; Fojn, O A; Galassi, M E; Champion, C; Rivarola, R D
2014-01-01
Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. PMID:23415107
Past analogs of recent climate anomalies and impacts in Portugal. Droughts, storms and heat waves
NASA Astrophysics Data System (ADS)
Alcoforado, M. J.; Nunes, M. F.
2009-09-01
An indexed reconstruction of precipitation variability, based on documentary and instrumental data, has been done for southern Portugal starting in 1675. The descriptions of the extreme events in the documentary sources have also supplied information about their impacts. We will compare past and recent extreme weather events in Portugal, their causes and their impacts on society. We have selected periods of winter droughts, of storms that triggered great floods and of heat waves. There are a number of documentary sources dating from 1693-94 indicating that that there was no rainfall from December 1693 to at least November 1694 with the exception of light showers in June. Several pro-pluvia rogations ceremonies took place all over the country, even in the Northwest that is generally rainy. There are numerous descriptions of the impact of droughts on agriculture, of shortage of cereals, of escalating prices and the subsequent generalised famine. An analogy will be made for the 20th century using the 1980-81 winter drought that lasted roughly the same time and which also had severe social and economic impacts. The decrease in production of hydroelectric energy (50% below average) between January and July 1981 is also pointed out. In both cases, the lack of rainfall was partly due to a ridge that stayed over the Eastern Atlantic and kept Iberia in aerologic shelter. Apart from urban flash floods there are two types of floods in Portugal: (i) floods from the big river basins (Tagus, Mondego and Douro) that are due to the frequent passage of westerly frontal depressions during days or weeks; and (ii) floods of the small river basins due to convective depressions that affect small areas. The December 1739 flood, caused by the overflow of the great rivers, will be compared with the ones that occurred in February 1978. Both were caused by intensive precipitation all over the country at a time when the soil was already saturated with water from previous rainfall. The damages were vast in both occasions including loss of life. Two poems and other documentary sources supply detailed and credible information on the 1739 flood that hit Portugal from North to South. A heat wave in June-July 1842 has been selected. There are already instrumental data available for the former (Franzini station), retrieved from medical journals as well as descriptions of impacts on several regions in the country. The 1842 heat wave will be compared with more recent heat waves like the June 1981 that had very serious impact on public health and on the country's economy. We will also analyse the heat waves of July 1991 and August 2003. The latter was particularly long-lasting with serious consequences ranging from extensive forest fires to losses in agriculture and impact on the population health, although the registered mortality was lower than in 1981 probably due to improved alert systems and Public Health Welfare State.
NASA Astrophysics Data System (ADS)
Langhamer, Olivia; Wilhelmsson, Dan; Engström, Jens
2009-04-01
Little is known about the effects of offshore energy installations on the marine environment, and further research could assist in minimizing environmental risks as well as in enhancing potential positive effects on the marine environment. While biofouling on marine energy conversion devices on one hand has the potential to be an engineering concern, these structures can also affect biodiversity by functioning as artificial reefs. The Lysekil Project is a test park for wave power located at the Swedish west coast. Here, buoys acting as point absorbers on the surface are connected to generators anchored on concrete foundations on the seabed. In this study we investigated the colonisation of foundations by invertebrates and fish, as well as fouling assemblages on buoys. We examined the influence of surface orientation of the wave power foundations on epibenthic colonisation, and made observations of habitat use by fish and crustaceans during three years of submergence. We also examined fouling assemblages on buoys and calculated the effects of biofouling on the energy absorption of the wave power buoys. On foundations we demonstrated a succession in colonisation over time with a higher degree of coverage on vertical surfaces. Buoys were dominated by the blue mussel Mytilus edulis. Calculations indicated that biofouling have no significant effect in the energy absorption on a buoy working as a point absorber. This study is the first structured investigation on marine organisms associated with wave power devices.
Non-dipolar Wilson links for transverse-momentum-dependent wave functions
NASA Astrophysics Data System (ADS)
Li, Hsiang-nan; Wang, Yu-Ming
2015-06-01
We propose a new definition of a transverse-momentum-dependent (TMD) wave function with simpler soft subtraction for k T factorization of hard exclusive processes. The un-subtracted wave function involves two pieces of non-light-like Wilson links oriented in different directions, so that the rapidity singularity appearing in usual k T factorization is regularized, and the pinched singularity from Wilson-link self-energy corrections is alleviated to a logarithmic one. In particular no soft function is needed, when the two pieces of Wilson links are orthogonal to each other. We show explicitly at one-loop level that the simpler definition with the non-dipolar Wilson links exhibits the same infrared behavior as the one with the dipolar Wilson links and complicated soft subtraction. It is pointed out that both definitions reduce to the naive TMD wave function as the non-light-like Wilson links approach to the light cone. Their equivalence is then extended to all orders by considering the evolution in the Wilson-link rapidity.
One-particle correlation function in evanescent wave dynamic light scattering
NASA Astrophysics Data System (ADS)
Lisicki, Maciej; Cichocki, Bogdan; Dhont, Jan K. G.; Lang, Peter R.
2012-05-01
In order to interpret measured intensity autocorrelation functions obtained in evanescent wave scattering, their initial decay rates have been analyzed recently [P. Holmqvist, J. K. G. Dhont, and P. R. Lang, Phys. Rev. E 74, 021402 (2006), 10.1103/PhysRevE.74.021402; B. Cichocki, E. Wajnryb, J. Blawzdziewicz, J. K. G. Dhont, and P. R. Lang, J. Chem. Phys. 132, 074704 (2010), 10.1063/1.3305328; J. W. Swan and J. F. Brady, J. Chem. Phys. 135, 014701 (2011)], 10.1063/1.3604530. A theoretical analysis of the longer time dependence of evanescent wave autocorrelation functions, beyond the initial decay, is still lacking. In this paper we present such an analysis for very dilute suspensions of spherical colloids. We present simulation results, a comparison to cumulant expansions, and experiments. An efficient simulation method is developed which takes advantage of the particular mathematical structure of the time-evolution equation of the probability density function of the position coordinate of the colloidal sphere. The computer simulation results are compared with analytic, first and second order cumulant expansions. The only available analytical result for the full time dependence of evanescent wave autocorrelation functions [K. H. Lan, N. Ostrowsky, and D. Sornette, Phys. Rev. Lett. 57, 17 (1986)], 10.1103/PhysRevLett.57.17, that neglects hydrodynamic interactions between the colloidal spheres and the wall, is shown to be quite inaccurate. Experimental results are presented and compared to the simulations and cumulant expansions.
On the Origin of d-WAVE Pair Functions in HIGH-Tc Superconductivity
NASA Astrophysics Data System (ADS)
Mattis, Daniel C.
We argue that the usual Hubbard's model produces only s-wave pairing functions and, even then, only at unphysically large values of the lumped parameter J≡4t2/U. It follows that a reliable theory of high-Tc superconductivity has to include additional features if it is to reproduce the d-wave gap. We test the effects of an alternating potential caused by a charge stripe, on the ground state of the Hubbard model in strong-coupling. If we "fine tune" we do find the d-waves. However, a better-formulated version of a three-band model yields a sturdier theory of pair formation in high-Tc superconductivity. The coupling constant g1=t2/V factors out, hence it serves only to establish the unit of energy; the underlying Hamiltonian is universal. We outline the principal properties of this model, including the intimate relation between charge-density stripes and the d-wave pair function, its rejection of 45° stripes (checkerboard pattern), and other concerns.
Kinetic Alfven wave in the presence of kappa distribution function in plasma sheet boundary layer
Shrivastava, G. Ahirwar, G.; Shrivastava, J.
2015-07-31
The particle aspect approach is adopted to investigate the trajectories of charged particles in the electromagnetic field of kinetic Alfven wave. Expressions are found for the dispersion relation, damping/growth rate and associated currents in the presence of kappa distribution function. Kinetic effect of electrons and ions are included to study kinetic Alfven wave because both are important in the transition region. It is found that the ratio β of electron thermal energy density to magnetic field energy density and the ratio of ion to electron thermal temperature (T{sub i}/T{sub e}), and kappa distribution function affect the dispersion relation, damping/growth rate and associated currents in both cases(warm and cold electron limit).The treatment of kinetic Alfven wave instability is based on assumption that the plasma consist of resonant and non resonant particles. The resonant particles participate in an energy exchange process, whereas the non resonant particles support the oscillatory motion of the wave.
NASA Astrophysics Data System (ADS)
Bordes, C.; Sénéchal, P.; Barrière, J.; Brito, D.; Normandin, E.; Jougnot, D.
2015-03-01
Seismic waves propagating in a porous medium, under favourable conditions, generate measurable electromagnetic fields due to electrokinetic effects. It has been proposed, following experimental and numerical studies, that these so-called `seismoelectromagnetic' couplings depend on pore fluid properties. The theoretical frame describing these phenomena are based on the original Biot's theory, assuming that pores are fluid-filled. We study here the impact of a partially saturated medium on amplitudes of those seismoelectric couplings by comparing experimental data to an effective fluid model. We have built a 1-m-length-scale experiment designed for imbibition and drainage of an homogeneous silica sand; the experimental set-up includes a seismic source, accelerometers, electric dipoles and capacitance probes in order to monitor seismic and seismoelectric fields during water saturation. Apparent velocities and frequency spectra (in the kiloHertz range) are derived from seismic and electrical measurements during experiments in varying saturation conditions. Amplitudes of seismic and seismoelectric waves and their ratios (i.e. transfer functions) are discussed using a spectral analysis performed by continuous wavelet transform. The experiments reveal that amplitude ratios of seismic to coseismic electric signals remain rather constant as a function of the water saturation in the Sw = [0.2-0.9] range, consistently with theoretically predicted transfer functions.
The Transfer Function Model (TFM) as a Tool for Simulating Gravity Wave Phenomena in the Mesosphere
NASA Astrophysics Data System (ADS)
Porter, H.; Mayr, H.; Moore, J.; Wilson, S.; Armaly, A.
2008-12-01
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.
Impact Wave Monitoring in Soil Using a Dynamic Fiber Sensor Based on Stimulated Brillouin Scattering
Cui, Qingsong; Pamukcu, Sibel; Pervizpour, Mesut
2015-01-01
The impact wave response of soil due to a ball drop is monitored on a 30.5 cm by 30.5 cm square soil box using a fiber sensor with dynamic strain sensing capability. The experiments are conducted in real time using a simple one-laser one-modulator configuration with stimulated Brillouin scattering. The embedded BOTDA sensor grid successfully monitored the distribution and evolution of the inner strains of a sand bed during a mass impact on its surface. The measurement of the distributed dynamic strains was possible in several milliseconds and with 1 cm actual location resolution. This paper presents a time-domain signal analysis utilized for determining the dynamic strains in embedded fiber sensor. The results demonstrate the method to be a promising one for detection of subsurface vibration and movement in geotechnical Structure Health Monitoring (SHM). PMID:25856327
Coupling of surge and waves for an Ivan-like hurricane impacting the Tampa Bay, Florida region
NASA Astrophysics Data System (ADS)
Huang, Yong; Weisberg, Robert H.; Zheng, Lianyuan
2010-12-01
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.
Investigation of dam-break induced shock waves impact on a vertical wall
NASA Astrophysics Data System (ADS)
Kocaman, Selahattin; Ozmen-Cagatay, Hatice
2015-06-01
In the present study, experimental tests and VOF-based CFD simulations concerning impact of dam-break induced shock waves on a vertical wall at downstream end were investigated. New laboratory experiments were carried out in a rectangular flume with a smooth horizontal wet bed for two different tailwater levels. Image processing was used for flow measurement and time evolutions of water levels were determined effectively by means of synchronous recorded video images of the flow. This study scrutinized formation and travelling of negative wave towards upstream direction, which was resulted from the reflection of flood wave against downstream end wall. In numerical simulation, two distinct approaches available in FLOW-3D were used: Reynolds- averaged Navier-Stokes equations (RANS) with the k-ε turbulence model and the Shallow Water Equations (SWEs). The measured results were then compared with those of numerical simulations and reasonable agreements were achieved. General agreement between laboratory measurements and RANS solution was better than that of SWE.
Summary of the mortality impact assessment of the 2003 heat wave in France.
Pirard, P; Vandentorren, S; Pascal, M; Laaidi, K; Le Tertre, A; Cassadou, S; Ledrans, M
2005-07-01
France experienced a record-breaking heat wave between 2 and 15 August 2003. All the French regions were affected by this heat wave, which resulted in an excess of 14 800 deaths between 1 and 20 August. The increase in the number of excess deaths followed the same pattern as the increase in temperatures. No deviance from the normal death rate was observed in the month of August during the last third of the month, nor during the following three months. There was a clear discrepancy in the impact of the heat wave from city to city. If the effect of duration of consecutive days with high minimal temperatures and deviance with the seasonal normal temperature was patent, this could not explain all of the observed variability of the death incidence. The victims were mainly elderly women older than 75 years. In terms of relative risk and contribution to the global toll, deaths linked to heat were the most important. Based on these results, the French government developed a Heat Health Watch Warning System and set up a preventive action plan for each region in 2004. PMID:16088047
Development of a shock wave adhesion test for composite bonds by pulsed laser and mechanical impacts
NASA Astrophysics Data System (ADS)
Ecault, R.; Boustie, M.; Touchard, F.; Arrigoni, M.; Berthe, L.
2014-05-01
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.
Development of a shock wave adhesion test for composite bonds by laser pulsed and mechanical impacts
NASA Astrophysics Data System (ADS)
Ecault, Romain; Boustie, Michel; Touchard, Fabienne; Arrigoni, Michel; Berthe, Laurent; CNRS Collaboration
2013-06-01
Evaluating the bonding quality of composite material is becoming one of the main challenges faced by aeronautic industries. This work aims 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 bond without any mechanical contact. The resulting damage has been quantified using different method 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 since it has often fixed parameters. That is why mechanical impacts bonded composites were also performed in this work. By changing the thickness of aluminum projectiles, the tensile stresses generated by the shock wave propagation were moved toward the composite/bond interface. The observations made prove that the optimization of the technique is possible. The key parameters for the development of a bonding test using shock wave have been identified.
Hadron wave functions as a probe of a two-color baryonic medium
NASA Astrophysics Data System (ADS)
Amato, Alessandro; Giudice, Pietro; Hands, Simon
2015-04-01
The properties of the ground state of two-color QCD at non-zero baryon chemical potential μ present an interesting problem in strongly interacting gauge theory; in particular the nature of the physically relevant degrees of freedom in the superfluid phase in the post-onset regime μ > m π /2 still needs clarification. In this study we present evidence for in-medium effects at high μ by studying the wave functions of mesonic and diquark states using orthodox lattice simulation techniques, made possible by the absence of a sign problem for the model with N f = 2. Our results show that beyond onset the spatial extent of hadrons decreases as μ grows, and that the wave function profiles are consistent with the existence of a dynamically gapped Fermi surface in this regime.
Calculations of properties of screened He-like systems using correlated wave functions.
Dai, S T; Solovyova, A; Winkler, P
2001-07-01
The purpose of the present study is twofold. First, the techniques of correlated wave functions for two-electron systems have been extended to obtain results for P and D states in a screening environment, and in particular for Debye screening. In these calculations, the satisfaction of both the quantum virial theorem and a related sum rule has been enforced and found to provide a high degree of stability of the solutions. Second, in order to facilitate the general use of correlated wave functions in combination with sum rule stability criteria, a rather systematic computational approach to this notoriously cumbersome method has been developed and thoroughly discussed here. Accurate calculations for few-electron systems are of interest to plasma diagnostics; in particular, when inaccuracies in binding energies are drastically magnified as they occur in exponents of Boltzmann factors. PMID:11461411
Donor wave functions delocalization in silicon nanowires: the peculiar [011] orientation.
Petretto, Guido; Debernardi, Alberto; Fanciulli, Marco
2013-10-01
The localization of the donor electron wave function can be of key importance in various silicon applications, since for example it determines the interactions between neighboring donors. Interestingly, the physical confinement of the electrons in quasi-one-dimensional nanostructures, like silicon nanowires, noticeably affects this property. Using fully ab initio calculations, we show that the delocalization of the donor electron wave function along the axis of a nanowire is much greater in [011] oriented nanowires for phosphorus and selenium donors. We also demonstrate that its value can be controlled by applying a compressive or tensile uniaxial strain. Finally, we discuss the implications of these features from both an experimental and a theoretical point of view. PMID:23984940
Perturbations in vibrational diatomic spectra: Factorization of the molecular wave function
NASA Astrophysics Data System (ADS)
Lefebvre, R.
2015-02-01
The coupling between two electronic states of a diatomic molecule may lead to an erratic behaviour of the associated vibrational energies. An example is the homogeneous coupling between the valence b' state and the Rydberg c' state of the N2 molecule, both of symmetry 1 Σu + . The standard treatment of such a situation is to write the wave function as a sum of two Born-Oppenheimer products. It has recently been argued [L. S. Cederbaum, J. Chem. Phys. 138, 224110 (2013); N. I. Gidopoulos and E. K. U. Gross, Philos. Trans. R. Soc., A 372, 20130059 (2014)] that even in such a case the wave function should be representable as a single product, with an electronic factor depending parametrically on nuclear positions and a nuclear factor. We setup such a representation in the case of the perturbations in the N2 molecule.
Velocity and attenuation of scalar and elastic waves in random media: a spectral function approach.
Calvet, Marie; Margerin, Ludovic
2012-03-01
This paper investigates the scattering of scalar and elastic waves in two-phase materials and single-mineral-cubic, hexagonal, orthorhombic-polycrystalline aggregates with randomly oriented grains. Based on the Dyson equation for the mean field, explicit expressions for the imaginary part of Green's function in the frequency-wavenumber domain (ω, p), also known as the spectral function, are derived. This approach allows the identification of propagating modes with their relative contribution, and the computation of both attenuation and phase velocity for each mode. The results should be valid from the Rayleigh (low-frequency) to the geometrical optics (high-frequency) regime. Comparisons with other approaches are presented for both scalar and elastic waves. PMID:22423683
The Hartle-Hawking wave function in 2D causal set quantum gravity
NASA Astrophysics Data System (ADS)
Glaser, Lisa; Surya, Sumati
2016-03-01
We define the Hartle-Hawking no-boundary wave function for causal set theory (CST) over the discrete analogs of spacelike hypersurfaces. Using Markov Chain Monte Carlo and numerical integration methods we analyze the wave function in non-perturbative 2D CST. We find that in the low-temperature regime it is dominated by causal sets which have no continuum counterparts but possess physically interesting geometric properties. Not only do they exhibit a rapid spatial expansion with respect to the discrete proper time, but a high degree of spatial homogeneity. The latter is due to the extensive overlap of the causal pasts of the elements in the final discrete hypersurface and corresponds to high graph connectivity. Our results thus suggest new possibilities for the role of quantum gravity in the observable Universe.
Perturbations in vibrational diatomic spectra: Factorization of the molecular wave function
Lefebvre, R.
2015-02-21
The coupling between two electronic states of a diatomic molecule may lead to an erratic behaviour of the associated vibrational energies. An example is the homogeneous coupling between the valence b′ state and the Rydberg c′ state of the N{sub 2} molecule, both of symmetry {sup 1}Σ{sub u}{sup +}. The standard treatment of such a situation is to write the wave function as a sum of two Born-Oppenheimer products. It has recently been argued [L. S. Cederbaum, J. Chem. Phys. 138, 224110 (2013); N. I. Gidopoulos and E. K. U. Gross, Philos. Trans. R. Soc., A 372, 20130059 (2014)] that even in such a case the wave function should be representable as a single product, with an electronic factor depending parametrically on nuclear positions and a nuclear factor. We setup such a representation in the case of the perturbations in the N{sub 2} molecule.
NASA Technical Reports Server (NTRS)
Weissman, D. E.; Johnson, J. W.
1984-01-01
The directional spectrum and the microwave modulation transfer function of ocean waves can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with ocean wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, wave orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the ocean directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.
NASA Technical Reports Server (NTRS)
Weissman, D. E.; Johnson, J. W.
1986-01-01
The directional spectrum and the microwave modulation transfer function of ocean waves can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with ocean wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, wave orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the ocean directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.
Probing wave function collapse models with a classically driven mechanical oscillator
NASA Astrophysics Data System (ADS)
Ho, Melvyn; Lafont, Ambroise; Sangouard, Nicolas; Sekatski, Pavel
2016-03-01
We show that the interaction of a pulsed laser light with a mechanical oscillator through the radiation pressure results in an opto-mechanical entangled state in which the photon number is correlated with the oscillator position. Interestingly, the mechanical oscillator can be delocalized over a large range of positions when driven by an intense laser light. This provides a simple yet sensitive method to probe hypothetical post-quantum theories including an explicit wave function collapse model, like the Diosi & Penrose model. We propose an entanglement witness to reveal the quantum nature of this opto-mechanical state as well as an optical technique to record the decoherence of the mechanical oscillator. We also report on a detailed feasibility study giving the experimental challenges that need to be overcome in order to confirm or rule out predictions from explicit wave function collapse models.
Conductance of one-dimensional quantum wires with anomalous electron wave-function localization
NASA Astrophysics Data System (ADS)
Amanatidis, Ilias; Kleftogiannis, Ioannis; Falceto, Fernando; Gopar, Víctor A.
2012-06-01
We study the statistics of the conductance g through one-dimensional disordered systems where electron wave functions decay spatially as |ψ|˜exp(-λrα) for 0<α<1, λ being a constant. In contrast to the conventional Anderson localization where |ψ|˜exp(-λr) and the conductance statistics is determined by a single parameter, the mean free path, here we show that when the wave function is anomalously localized (α<1), the full statistics of the conductance is determined by the average
Harvesting broadband kinetic impact energy from mechanical triggering/vibration and water waves.
Wen, Xiaonan; Yang, Weiqing; Jing, Qingshen; Wang, Zhong Lin
2014-07-22
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 μA, 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
Pyper, N. C.; Kampp, Marco; Whelan, Colm T.
2005-05-15
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.
Impact of nonlinear waves on the dissipation of internal tidal energy at a shelf break
NASA Astrophysics Data System (ADS)
Inall, Mark E.; Rippeth, Tom P.; Sherwin, Toby J.
2000-04-01
The vertical and temporal structure of the dissipation of turbulent kinetic energy within the internal tide at a location 5 km shoreward of the shelf break on the Malin Shelf has been determined using a combination of the free-falling light yo-yo profiler and acoustic doppler current profilers. Two distinct internal wave regimes were encountered: period I in which large-amplitude high-frequency nonlinear internal waves (NIWs) occurred (around neap tides) and period II in which the internal wave spectral continuum was not dominated by any particular frequency band (around spring tides). Empirical orthogonal function analysis shows that for the low-frequency waves, 76% of the variance was described by mode 1, rising to 95% for the high-frequency waves. During period I the dissipation and vertical mixing were characterized by the NIWs, and 70% of the dissipation occurred in the bottom boundary layer. During period II the depth-integrated dissipation was more evenly distributed throughout the tidal cycle, whereas vertical mixing was greatly enhanced during a single hour long episode of elevated thermocline dissipation coincident with weakened stratification. During both periods I and II ˜30% of the total measured dissipation occurred within the thermocline when averaged over 12.4 hours; the remainder occurred within the bottom boundary layer(BBL). Tidal average values for depth-integrated dissipation and vertical eddy diffusivity for period I (II) were 1.1×10-2 W m-2 (4.0×10-2 W m-2) and 5 cm2 s-1 (12 cm2 s-1), respectively. Decay rates and internal damping are discussed, and vertical heat fluxes are estimated. Observed dissipation rates are compared with a simple model for BBL dissipation.
Short range structure of hadron and nuclear wave functions at high x
Hoyer, P.; Brodsky, S.J.
1990-11-01
We discuss the short-range structure of hadronic and nuclear wave functions expected in QCD. In addition to the extrinsic'' contributions associated with radiation from single partons, there is an intrinsic'' hardness of the high-mass fluctuations of the wave function due to the spatial overlap of two or more partons. We argue that intrinsically-hard partons, having large mass and/or large transverse momentum, will dominate in the region of large Feynman x{sub F}. Their rescattering in nuclear targets is expected to be larger than for extrinsically-hard partons, leading to a suppressed production cross section for hadrons scattering on heavy nuclei. Experimental evidence for this exists for open chars. J/{psi}, and {gamma} production at large x{sub F}. The effects of intrinsic hardness may be particularly striking in nuclear wave functions, where the overlap of partons belonging to different nucleons can give rise to cumulative (x > 1) phenomena. The data on backward cumulative particle production from nuclei supports the existence of an intrinsically-hard component in nuclear wave functions. Partons at large x{sub F} may also be associated with the enhanced subthreshold production of particles observed in hadron-nucleus and nucleus-nucleus collisions. We discuss the evidence for anomalies in the large angle pp {yields} pp cross section near the charm threshold. Arguments are presented that chromium states may bind to nuclei through the QCD Van der Waals force. This would lead to a striking signal in charm production near threshold. 49 refs., 7 figs.
Counting Rules, Holographic Wave Functions, Meromorphization and Quark-Hadron Duality
Anatoly Radyushkin
2006-05-11
We start with study of the meson form factor F{sub M} (Q{sup 2}) constructed using recently proposed holographic light-front wave functions. We find that its asymptotic behavior is generated by soft Feynman mechanism rather than by short distance dynamics. In this scenario, both hard and soft contributions are present, and the ''observed'' quark counting rules for hadronic form factors is an approximate and transitional phenomenon resulting from long-distance dynamics, Feynman mechanism in its preasymptotic regime.
Stochastic quasiclassical wave function of the Universe from the third quantization procedure
NASA Astrophysics Data System (ADS)
Ivanov, P.; Chernov, S. V.
2015-09-01
We study quantized solutions of the Wheeler de Witt (WdW) equation describing a closed Friedmann-Robertson-Walker universe with a ? term and a set of massless scalar fields. We show that when ? ?1 in the natural units and the standard in-vacuum state is considered, either wave function of the universe, ? , or its derivative with respect to the scale factor, a , behave as random quasiclassical fields at sufficiently large values of a . The former case is realized when 1 ?a ?e2/3 ? , while the latter is valid when a ?e2/3 ? . The statistical rms value of the wave function is proportional to the Hartle-Hawking wave function for a closed universe with a ? term. Alternatively, the behavior of our system at large values of a can be described in terms of a density matrix corresponding to a mixed state, which is directly determined by statistical properties of ? . Similar to ? , the density matrix can be considered as a c-number valued in the position and momentum representations. The probability distribution to find a universe with particular values of the scale factor and field amplitudes following from this density matrix is again proportional to that of the Hartle-Hawking wave function, while the probability distribution over field velocities is nontrivial and different from what follows from the Hartle and Hawking formalism. We suppose that a similar behavior of ? can be found in all models exhibiting copious production of excitations with respect to the out-vacuum state associated with classical trajectories at large values of a . Thus, the third quantization procedure may provide a "boundary condition" for classical solutions of the WdW equation. Contrary to the previous proposals, in our case two equivalent descriptions of this classical solutions are possible. Either ? can be regarded as a stochastic classical quantity or the system can be viewed as being in a mixed state defined over classical solutions to the WdW equation.
Ex vivo Characterization of Blast Wave Impact and Spinal Cord Tissue Deformation
NASA Astrophysics Data System (ADS)
Chen, Jun; Gao, Jian; Connell, Sean; Shi, Riyi
2010-11-01
Primary blast injury on central nervous system is responsible for many of the war related casualties and mortalities. An ex vivo model system is developed to introduce a blast wave, generated from a shock tube, directly to spinal cord tissue sample. A high-speed shadowgraph system is utilized to visualize the development of the blast wave and its interaction with tissue sample. Surface deformation of the tissue sample is also measured for the analysis of internal stress and possible injury occurred within the tissue sample. Understanding the temporal development of the blast-tissue interaction provides valuable input for modeling blast-induced neurotrauma. Tracking the sample surface deformation as a function of time provides realistic boundary conditions for numerical simulation of injury process.
Working With the Wave Equation in Aeroacoustics: The Pleasures of Generalized Functions
NASA Technical Reports Server (NTRS)
Farassat, F.; Brentner, Kenneth S.; Dunn, mark H.
2007-01-01
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.
NASA Astrophysics Data System (ADS)
Rodrigues, N. S.; Kulkarni, V.; Gao, J.; Chen, J.; Sojka, P. E.
2015-03-01
The current study focuses on experimentally and theoretically improving the characterization of the drop size and drop velocity for like-on-like doublet impinging jets. The experimental measurements were made using phase Doppler anemometry (PDA) at jet Weber numbers We j corresponding to the impact wave regime of impinging jet atomization. A more suitable dynamic range was used for PDA measurements compared to the literature, resulting in more accurate experimental measurements for drop diameters and velocities. There is some disagreement in the literature regarding the ability of linear stability analysis to accurately predict drop diameters in the impact wave regime. This work seeks to provide some clarity. It was discovered that the assumed uniform jet velocity profile was a contributing factor for deviation between diameter predictions based on models in the literature and experimental measurements. Analytical expressions that depend on parameters based on the assumed jet velocity profile are presented in this work. Predictions based on the parabolic and 1/7th power law turbulent profiles were considered and show better agreement with the experimental measurements compared to predictions based on the previous models. Experimental mean drop velocity measurements were compared with predictions from a force balance analysis, and it was observed that the assumed jet velocity profile also influences the predicted velocities, with the turbulent profile agreeing best with the experimental mean velocity. It is concluded that the assumed jet velocity profile has a predominant effect on drop diameter and velocity predictions.
Impact of kudzu and puerarin on sperm function.
Gray, Sandra L; Lackey, Brett R; Boone, William R
2015-06-01
The goal of this study was to investigate the impact of kudzu (Pueraria mirifica) and the isoflavone puerarin in functional toxicological tests on spermatozoa and to assess the affinity of extracts and pure isoflavones for estrogen receptor (ER)-alpha and -beta (ER?, ER?) in receptor binding assays. Capacitation, acrosome reaction and chromatin decondensation in spermatozoa were analyzed using microscopic analysis. Kudzu, but not puerarin, reduced motility of sperm. Puerarin reduced the percent spontaneous acrosome reaction in spermatozoa. The pathways used by kudzu that affect sperm function are not fully mirrored by puerarin. Puerarin, kudzu and its other phytoestrogenic components displayed preferential affinity for ER?, however the diverse effects of kudzu and puerarin on sperm function implicate the involvement of multiple signaling systems. PMID:25828059
Many-body Localization Transition in Rokhsar-Kivelson-type wave functions
NASA Astrophysics Data System (ADS)
Chen, Xiao; Yu, Xiongjie; Cho, Gil Young; Clark, Bryan; Fradkin, Eduardo
We construct a family of many-body wave functions to study the many-body localization phase transition. The wave functions have a Rokhsar-Kivelson form, in which the weight for the configurations are chosen from the Gibbs weights of a classical spin glass model, known as the Random Energy Model, multiplied by a random sign structure to represent a highly excited state. These wave functions show a phase transition into an MBL phase. In addition, we see three regimes of entanglement scaling with subsystem size: scaling with entanglement corresponding to an infinite temperature thermal phase, constant scaling, and a sub-extensive scaling between these limits. Near the phase transition point, the fluctuations of the Renyi entropies are non-Gaussian. We find that Renyi entropies with different Renyi index transition into the MBL phase at different points and have different scaling behavior, suggesting a multifractal behavior. This work was supported in part by DMR-1064319 and DMR-1408713 (XC,GYC,EF) at the University of Illinois, PHY11-25915 at KITP (EF), DOE, SciDAC FG02-12ER46875 (BKC and XY), and the Brain Korea 21 PLUS Project of Korea Government (GYC).
Emergence of complex and spinor wave functions in scale relativity. I. Nature of scale variables
Nottale, Laurent; Célérier, Marie-Noëlle
2013-11-15
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.
The energy levels and the corresponding normalized wave functions for a model of a compressed atom
NASA Astrophysics Data System (ADS)
Frman, Per Olof; Yngve, Staffan; Frman, Nanny
1987-08-01
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 Frman and Frman, 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.
Impact of Anthropogenic Land Cover Change on Heat Waves : the summer 2003 as a testbed.
NASA Astrophysics Data System (ADS)
Stéfanon, Marc; Schindler, Solveig; Drobinski, Philippe; de Noblet-Ducoudré, Nathalie; D'Andrea, Fabio
2013-04-01
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 .
Catastrophic impact of typhoon waves on coral communities in the Ryukyu Islands under global warming
NASA Astrophysics Data System (ADS)
Hongo, Chuki; Kawamata, Hideki; Goto, Kazuhisa
2012-06-01
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.
NASA Astrophysics Data System (ADS)
Xiao, Longfei; Yang, Jianmin; Peng, Tao; Tao, Longbin
2016-02-01
The meshless Numerical Wave Tank (NWT) has been developed based on the collocation method and the radial basis function. For simulating short waves, a free surface interpolation approach is proposed in this study in order to mitigate numerical dissipation and accelerate the simulation. A number of fundamental free surface nodes are employed in the procedure of solving algebraic equations with a full coefficient matrix, while many more free surface nodes are utilized in the time-stepping and smoothing procedure by applying the interpolation technique between each adjacent fundamental nodes. The NWT with the free surface interpolation approach is applied to simulate regular waves and irregular waves, and is then validated by both analytical solutions and experimental results. The numerical results are significantly improved by using the approach to increase the number of free surface boundary nodes, whilst the time consumption increases proportionally. For shorter waves, more interpolation nodes need be used. The good agreement between the present numerical results and the analytical and experimental results indicates that the free surface interpolation approach succeeds in rapidly and accurately simulating the propagation of short waves and irregular waves, covering a wide range of wave frequencies.
[The stimulating impact of light on brain cognition function].
Vandewalle, Gilles
2014-10-01
Light regulates multiple non-visual circadian, neuroendocrine, and neurobehavioral functions, and conveys a strong stimulating signal for alert-ness and cognition. This review summarizes a series of neuroimaging studies investigating the brain mechanisms underlying the latter stimulating impact of light. Results of these studies are compatible with a scenario where light would first hit subcortical areas involved in arousal regulation before affecting cortical areas involved in the ongoing non-visual cognitive process, and then cognitive performance. Recent data demonstrated that the non-visual impact of light is most likely triggered via outputs from intrinsically photosensitive retinal ganglion cells (ipRGC) expressing the photopigment melanopsin, which are maximally sensitive to blue light. In addition, the stimulating impact of light is intimately related to wakefulness regulation as it changes with circadian phase and sleep pressure. Finally, markers of inter-individual difference have also been described: age, PERIOD3 genotype, and psychiatric status. This review emphasizes the importance of light for human brain cognitive function and for cognition in general. PMID:25311026
NASA Astrophysics Data System (ADS)
Gusarov, Sergey; Malmqvist, Per-ke; Lindh, Roland
2004-01-01
The value of the two-particle density function at coalescence is frequently used as an additional variable for formulating approximate exchange-correlation or correlation functionals. Here, its applications as one of the key variables for the construction of new DFT (preferably multi-determinant) functionals is investigated. The basic formalism is presented and it is shown that this replacement avoids some difficulty to construct a Fock matrix in a ROKS (restricted open-shell Kohn-Sham) method and also to reduce the 'double counting' of correlation energy in CASDFT (complete active space density functional theory) calculations. Calculations of excitation energies for transition metals and dissociation curves for diatomic molecules are presented as an example.
Two-dimensional Coulomb scattering of a quantum particle: Construction of radial wave functions
NASA Astrophysics Data System (ADS)
Pupyshev, V. V.
2016-01-01
We prove that radial wave functions of a charged quantum particle moving in a two-dimensional plane of the three-dimensional coordinate space and scattering by a Coulomb center at rest in the same plane are governed by the Coulomb equation with a half-integer index. We investigate the structure of these functions and consider three physically interesting limits: the non-Coulomb limit and high- and low-energy limits. We explicate the basic differences between two- and three-dimensional Coulomb scattering.
NASA Astrophysics Data System (ADS)
Lu, Lu; Wang, Zhiqiang; Zhang, Pengfei; Qiao, Chunhong; Fan, Chengyu; Zhang, Jinghui; Ji, Xiaoling
2015-08-01
Based on the characteristics of a hypergeometric function, the analytical expressions for the phase structure function and angle-of-arrival (AOA) fluctuations of plane and spherical waves propagating through oceanic turbulence are derived. The results are verified by comparing them with the numerical calculations of the definitions using four important parameters (i.e., the rate of dissipation of mean-squared temperature {χ }T, the rate of dissipation of kinetic energy per unit mass of fluid \\varepsilon , the ratio of temperature to salinity contribution to the refractive index spectrum w, and the Kolmogorov microscale η ). The relation between AOA fluctuations and the spatial coherence radius {ρ }0 is also investigated.
Acute effect of alcohol intake on sine-wave Cartesian and polar contrast sensitivity functions
Cavalcanti-Galdino, M.K.; da Silva, J.A.; Mendes, L.C.; dos Santos, N.A.; Simas, M.L.B.
2014-01-01
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
NASA Technical Reports Server (NTRS)
Leyva, Ivett A.; Clifford, Stephen M.
1993-01-01
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.
NASA Astrophysics Data System (ADS)
Pérez-Jiménez, Ángel J.; Pérez-Jordá, José M.; Sancho-García, Juan C.
2007-09-01
We propose a procedure that combines multiconfigurational (MC) wave functions with two-body density correlation functionals by transforming the latter into functionals of the MC natural orbitals and occupation numbers. The method is tested with the spectroscopic constants of a set of 11 diatomics, the diradical-involved automerization barrier of cyclobutadiene, the energy difference between triplet and open-shell singlet states in He and the methylene molecule, and the magnetic coupling constants of several systems, such as NiO, KNiF3, K2NiF4, La2CuO4, α-4-dehydrotoluene, 1,1',5,5'-tetramethyl-6,6'-dioxo-3,3'-biverdazyl, [Cu2Cl6]-2, copper(II) acetate monohidrate and H-He-H. The procedure is applied to the Colle-Salvetti [Theor. Chim. Acta 37, 329 (1975); 53, 55 (1979)], functional and to a size-consistent functional depending on the on-top pair density (F1-5-Neff). On average, the best results are provided by the transformed F1-5-Neff [J. Chem. Phys. 114, 2022 (2001)] functional.
Progress at the interface of wave-function and density-functional theories
Gidopoulos, Nikitas I.
2011-04-15
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.
NASA Astrophysics Data System (ADS)
Hasegawa, Jun-ya
2013-05-01
Solvatochromic effect in proteins and solutions was described by a configuration interaction singles (CIS) wave function with fragment-localized molecular orbitals. Coarse-grained analysis indicated that the CI wave function can be described by local excitations and charge-transfer (CT) excitations between the chromophore and the environment. We developed an atomic-orbital direct runcated CIS code and applied the excited states of retinal chromophore in bacteriorhodopsin and MeOH environments, and those of s-trans-acrolein in water. Number of excitation operators was significantly reduced by eliminating the CT excitations between the environmental fragments. The truncated CIS wave functions reproduced the original excitation energies very well.
The wave function and minimum uncertainty function of the bound quadratic Hamiltonian system
NASA Technical Reports Server (NTRS)
Yeon, Kyu Hwang; Um, Chung IN; George, T. F.
1994-01-01
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.
Assessment of canine sensory function by using sine-wave electrical stimuli paradigm.
Watabiki, Tomonari; Nagakura, Yukinori; Wegner, Kirsten; Kakimoto, Shuichiro; Tozier, Nicolle A; Malkmus, Shelle A; Yaksh, Tony L
2010-10-01
The paradigm of sine-wave electrical stimuli has been used for sensory neurological assessment in humans. In the present study, we applied the paradigm to the dog for the quantitative assessment of sensory function. Sine-wave electrical current stimuli at frequencies of 2000, 250, and 5Hz were delivered to bipolar electrodes attached to the skin surface of the hind paws. The stimulation intensity was gradually increased, and the minimum intensity required to elicit the lifting behavior in the stimulated paw was determined as current threshold (CT) for each of the three frequencies. Dogs consistently showed the lifting behavior at CTs without showing aversive behaviors such as vocalization and wriggling. The baseline CTs (mean+/-SEM, n=12) were 4430+/-110microA for CT2000, 2215+/-173microA for CT250, and 2305+/-152microA for CT5. The CTs immediately increased after bolus intravenous injection of fentanyl at 10microg/kg, although the significant increase disappeared within 1h. The time course for the CTs was parallel to that of plasma fentanyl concentration. In conclusion, the present study applied the paradigm of transcutaneous sine-wave electrical stimuli to the dog, and used the hind paw lifting as endpoint behavior. This paradigm is simple, non-invasive, useful in the assessment of sensory function, and can be adapted to investigate the pharmacokinetics/pharmacodynamics relation of drugs. Further studies are needed to give the conclusive interpretation of the endpoint behavior. PMID:20570687
Crustal structure of Nigeria and Southern Ghana, West Africa from P-wave receiver functions
NASA Astrophysics Data System (ADS)
Akpan, Ofonime; Nyblade, Andrew; Okereke, Chiedu; Oden, Michael; Emry, Erica; Julià, Jordi
2016-04-01
We report new estimates of crustal thickness (Moho depth), Poisson's ratio and shear-wave velocities for eleven broadband seismological stations in Nigeria and Ghana. Data used for this study came from teleseismic earthquakes recorded at epicentral distances between 30° and 95° and with moment magnitudes greater than or equal to 5.5. P-wave receiver functions were modeled using the Moho Ps arrival times, H-k stacking, and joint inversion of receiver functions and Rayleigh wave group velocities. The average crustal thickness of the stations in the Neoproterozoic basement complex of Nigeria is 36 km, and 23 km for the stations in the Cretaceous Benue Trough. The crustal structure of the Paleoproterozoic Birimian Terrain, and Neoproterozoic Dahomeyan Terrain and Togo Structural Unit in southern Ghana is similar, with an average Moho depth of 44 km. Poisson's ratios for all the stations range from 0.24 to 0.26, indicating a bulk felsic to intermediate crustal composition. The crustal structure of the basement complex in Nigeria is similar to the average crustal structure of Neoproterozoic terrains in other parts of Africa, but the two Neoproterozoic terrains in southern Ghana have a thicker crust with a thick mafic lower crust, ranging in thickness from 12 to 17 km. Both the thicker crust and thick mafic lower crustal section are consistent with many Precambrian suture zones, and thus we suggest that both features are relict from the collisional event during the formation of Gondwana.
Nath, Debashis; Chen, Wen; Zelin, Cai; Pogoreltsev, Alexander Ivanovich; Wei, Ke
2016-01-01
In the present study, we investigate the impact of stratospheric planetary wave reflection on tropospheric weather over Central Eurasia during the 2013 Sudden Stratospheric Warming (SSW) event. We analyze EP fluxes and Plumb wave activity fluxes to study the two and three dimensional aspects of wave propagation, respectively. The 2013 SSW event is excited by the combined influence of wavenumber 1 (WN1) and wavenumber 2 (WN2) planetary waves, which makes the event an unusual one and seems to have significant impact on tropospheric weather regime. We observe an extraordinary development of a ridge over the Siberian Tundra and the North Pacific during first development stage (last week of December 2012) and later from the North Atlantic in the second development stage (first week of January 2013), and these waves appear to be responsible for the excitation of the WN2 pattern during the SSW. The wave packets propagated upward and were then reflected back down to central Eurasia due to strong negative wind shear in the upper stratospheric polar jet, caused by the SSW event. Waves that propagated downward led to the formation of a deep trough over Eurasia and brought extreme cold weather over Kazakhstan, the Southern part of Russia and the Northwestern part of China during mid-January 2013. PMID:27051997
Schroter, R C; Leeming, A; Denny, E; Bharath, A; Marlin, D J
1999-07-01
Recently we proposed that exercise-induced pulmonary haemorrhage (EIPH) results from locomotory-impact-induced trauma by impact of the scapula on the chest wall during footfall and the consequent transmission of waves through the lung. A computational model has been developed to demonstrate that wave amplification and focusing occur in the dorsocaudal tip of the lung for waves originating on the anterior subscapular surface. The propagation of an acoustic wave was investigated in a simplified 2-dimensional representation of a vertical anterio-dorsal section of horse lung. It was demonstrated that a complicated pattern of waves is transmitted from the scapula to the dorsal region. Wave motion was characterised using the instantaneous rate of change of pressure with time (dp/dt) which is associated with lung injury. Due to wave reflection and focusing, dp/dt is transiently very high on the spinal and diaphragmatic lung walls, particularly in the vicinity of the dorsal tip. The model therefore predicts that lung injury may occur in the region in which EIPH is reported to originate. PMID:10659218
Nath, Debashis; Chen, Wen; Zelin, Cai; Pogoreltsev, Alexander Ivanovich; Wei, Ke
2016-01-01
In the present study, we investigate the impact of stratospheric planetary wave reflection on tropospheric weather over Central Eurasia during the 2013 Sudden Stratospheric Warming (SSW) event. We analyze EP fluxes and Plumb wave activity fluxes to study the two and three dimensional aspects of wave propagation, respectively. The 2013 SSW event is excited by the combined influence of wavenumber 1 (WN1) and wavenumber 2 (WN2) planetary waves, which makes the event an unusual one and seems to have significant impact on tropospheric weather regime. We observe an extraordinary development of a ridge over the Siberian Tundra and the North Pacific during first development stage (last week of December 2012) and later from the North Atlantic in the second development stage (first week of January 2013), and these waves appear to be responsible for the excitation of the WN2 pattern during the SSW. The wave packets propagated upward and were then reflected back down to central Eurasia due to strong negative wind shear in the upper stratospheric polar jet, caused by the SSW event. Waves that propagated downward led to the formation of a deep trough over Eurasia and brought extreme cold weather over Kazakhstan, the Southern part of Russia and the Northwestern part of China during mid-January 2013. PMID:27051997
An integrated perspective and functional impact of the mitochondrial acetylome.
Amado, Francisco M; Barros, António; Azevedo, Ana Lúcia; Vitorino, Rui; Ferreira, Rita
2014-06-01
Growing evidence suggests that a range of reversible protein post-translational modifications such as acetylation regulates mitochondria signalling, impacting cellular homeostasis. However, the extent of this type of regulation in the control of mitochondria functionality is just beginning to be discovered, aided by the availability of high-resolution mass spectrometers and bioinformatic tools. Data mining from literature on protein acetylation profiling focused on mitochondria isolated from tissues retrieved more than 1395 distinct proteins, corresponding to more than 4858 acetylation sites. ClueGo analysis of identified proteins highlighted oxidative phosphorylation, tricarboxylic acid cycle, fatty acid oxidation and amino acid metabolism as the biological processes more prone to regulation through acetylation. This review also examines the physiological relevance of protein acetylation on the molecular pathways harbored in mitochondria under distinct pathophysiological conditions as caloric restriction and alcohol-induced liver damage. This integrative perspective will certainly help to envisage future studies targeting the regulation of mitochondrial functionality. PMID:24661243
Evers, Joerg; Qamar, Shahid; Zubairy, M. Suhail
2007-05-15
We discuss localization and center-of-mass wave-function measurement of a quantum particle using multiple simultaneous dispersive interactions of the particle with different standing-wave fields. In particular, we consider objects with an internal structure consisting of a single ground state and several excited states. The transitions between ground and the corresponding excited states are coupled to the light fields in the dispersive limit, thus giving rise to a phase shift of the light field during the interaction. We show that multiple simultaneous measurements allow both an increase in the measurement or localization precision in a single direction and the performance of multidimensional measurements or localization. Further, we show that multiple measurements may relax the experimental requirements for each individual measurement.
Quantum quench in two dimensions using the variational Baeriswyl wave function
NASA Astrophysics Data System (ADS)
Dóra, Balázs; Haque, Masudul; Pollmann, Frank; Hetényi, Balázs
2016-03-01
By combining the Baeriswyl wave function with equilibrium and time-dependent variational principles, we develop a nonequilibrium formalism to study quantum quenches for two-dimensional spinless fermions with nearest-neighbor hopping and repulsion. The variational ground-state energy, the charge-density wave (CDW) order parameter, and the short-time dynamics agree convincingly with the results of numerically exact simulations. We find that, depending on the initial and final interaction strength, the quenched system either exhibits oscillatory behavior or relaxes to a time-independent steady state. The time-averaged expectation value of the CDW order parameter rises sharply when crossing from the steady-state regime to the oscillating regime, indicating that the system, being nonintegrable, shows signs of thermalization with an effective temperature above or below the equilibrium critical temperature, respectively.
Stafford, L.; Margot, J.; Moisan, M.; Khare, R.; Donnelly, V. M.
2009-01-12
Electron energy distribution functions (EEDFs) were measured in a 50 mTorr oxygen plasma column sustained by propagating surface waves. Trace-rare-gas-optical-emission spectroscopy was used to derive EEDFs by selecting lines to extract ''electron temperature''(T{sub e}) corresponding to either lower energy electrons that excite high-lying levels through stepwise excitation via metastable states or higher energy electrons that excite emission directly from the ground state. Lower energy T{sub e}'s decreased from 8 to 5.5 eV with distance from the wave launcher, while T{sub e}{approx_equal}6 eV for higher energy electrons and T{sub e}>20 eV for a high-energy tail. Mechanisms for such EEDFs are discussed.
Fattebert, J
2008-07-29
We describe an iterative algorithm to solve electronic structure problems in Density Functional Theory. The approach is presented as a Subspace Accelerated Inexact Newton (SAIN) solver for the non-linear Kohn-Sham equations. It is related to a class of iterative algorithms known as RMM-DIIS in the electronic structure community. The method is illustrated with examples of real applications using a finite difference discretization and multigrid preconditioning.
Averkiev, Boris B; Zhao, Yan; Truhlar, Donald G
2010-06-01
The structures of Pd(PH₃)₂ and Pt(PH₃)₂ complexes with ethene and conjugated CnH_{n+2} 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 C_{n}H_{n+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(PH₃)₂ is 2.5 kcal/mol for the ωB97 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 ωB97X-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.
NASA Technical Reports Server (NTRS)
Woods, D. Tod; Holzer, Thomas E.; Macgregor, Keith B.
1990-01-01
Lower transition region models with a balance between mechanical heating and radiative losses are expanded to include wave pressure effects. The models are used to study the simple damping length form of the heating function. The results are compared to the results obtained by Woods et al. (1990) for solutions in the lower transition region. The results suggest that a mixture of fast-mode and slow-mode waves may provide the appropriate heating mechanism in the lower transition region, with the decline in effective vertical wave speed caused by the refraction and eventual total reflection of the fast-mode wave resulting from the decreasing atmospheric density.
Functionally Univentricular Hearts: Impact of Pre-Natal Diagnosis
Corno, Antonio Francesco
2015-01-01
Within the last few decades the pre-natal echocardiographic diagnosis of congenital heart defects has made substantial progresses, particularly for the identification of complex malformation. Functionally univentricular hearts categorize a huge variety of heart malformations. Since no one of the patients with these congenital heart defects can ever undergo a bi-ventricular type of repair, early recognition and decision-making from the neonatal period are required in order to allow for appropriate multiple-step diagnostic and treatment procedures, either of interventional cardiology and/or surgery, on the pathway of univentricular heart. In the literature strong disagreements exist about the potential impact of the pre-natal diagnosis on the early and late outcomes of complex congenital heart defects. This review of the recent reports has been undertaken to better understand the impact of pre-natal diagnosis in functionally univentricular hearts taking into consideration the following topics: pre-natal screening, outcomes and survival, general morbidity, neurologic and developmental consequences, pregnancy management and delivery planning, resources utilization and costs/benefits issues, ethical implications, parents counseling, and interruption of pregnancy versus treatment. PMID:25774365
The impact of heat, cold, and heat waves on hospital admissions in eight cities in Korea
NASA Astrophysics Data System (ADS)
Son, Ji-Young; Bell, Michelle L.; Lee, Jong-Tae
2014-01-01
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.
The impact of soil degradation on soil functioning in Europe
NASA Astrophysics Data System (ADS)
Montanarella, Luca
2010-05-01
The European Commission has presented in September 2006 its Thematic Strategy for Soil Protection.The Thematic Strategy for Soil Protection consists of a Communication from the Commission to the other European Institutions, a proposal for a framework Directive (a European law), and an Impact Assessment. The Communication (COM(2006) 231) sets the frame. It defines the relevant soil functions for Europe and identifies the major threats. It explains why further action is needed to ensure a high level of soil protection, sets the overall objective of the Strategy and explains what kind of measures must be taken. It establishes a ten-year work program for the European Commission. The proposal for a framework Directive (COM(2006) 232) sets out common principles for protecting soils across the EU. Within this common framework, the EU Member States will be in a position to decide how best to protect soil and how use it in a sustainable way on their own territory. The Impact Assessment (SEC (2006) 1165 and SEC(2006) 620) contains an analysis of the economic, social and environmental impacts of the different options that were considered in the preparatory phase of the strategy and of the measures finally retained by the Commission. Since 2006 a large amount of new evidence has allowed to further document the extensive negative impacts of soil degradation on soil functioning in Europe. Extensive soil erosion, combined with a constant loss of soil organic carbon, have raised attention to the important role soils are playing within the climate change related processes. Other important processes are related to the loss of soil biodiversity, extensive soil sealing by housing and infrastructure, local and diffuse contamination by agricultural and industrial sources, compaction due to unsustainable agricultural practices and salinization by unsustainable irrigation practices. The extended impact assessment by the European Commission has attempted to quantify in monetary terms the actual economic impact of soil degradation in Europe.The total costs of soil degradation that could be assessed for erosion, organic matter decline, salinisation, landslides and contamination on the basis of available data, would be up to 38 billion annually for EU25. These estimates are necessarily wide ranging due to the lack of sufficient quantitative and qualitative data. Future research activities will have to address, in multidisciplinary teams, the social and economic aspects of soil degradation in Europe, in order to come up with more reliable estimates of the economic impact of soil degradation. A more reliable and updated system of indicators needs to be developed in order to cover the full cycle of the Driving forces-Pressures-State-Impact-Response (DPSIR) framework. Recent developments towards a new soil monitoring system for Europe will be presented as well as some of the recent outputs of the European Soil Data Centre (ESDAC).
Constraining the Lithospheric Structure of the Central Andes Using P- and S- wave Receiver Functions
NASA Astrophysics Data System (ADS)
Ryan, J. C.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Minaya, E.; Tavera, H.
2014-12-01
The Central Andean Plateau (CAP) has elevations in excess of 3 km, and is part of the Andean Cordillera that resulted in part from shortening along the western edge of South America as it was compressed between the subducting Nazca plate and underthrusting Brazilian cratonic lithosphere. We calculated P- and S-wave receiver functions for the Central Andean Uplift and Geodynamics of High Topography (CAUGHT) temporary deployment of broadband seismometers in the Bolivian orocline (12°-20°S) region to investigate crustal thickness and lithospheric structure. Migration of the receiver functions is done using common conversion point (CCP) stacks through a 3D shear velocity model from ambient noise tomography (Ward et al., 2013). The P- and S-wave receiver functions provide similar estimates of the depth to Moho under the CAP. Crustal thicknesses include 60-65 km thick crust underneath the Bolivian Altiplano, crust that varies from ~70 km to ~50 km underneath the Eastern Cordillera and Interandean zone, and thins to 50 to 40 km crust in the Subandes and the edge of the foreland. The variable crustal thickness of the Eastern Cordillera and Interandean zone ranges from >70 km associated with the Los Frailes volcanic field at 19°-20°S to ~55 km beneath the 6 km peaks of the Cordillera Real at ~16°S. From our S-wave receiver functions, that have no multiples that can interfere with deeper structure, we also identify structures below the Moho. Along a SW-NE line that runs near La Paz where we have our highest station density, the S-wave CCP receiver-function stacks show a strong negative polarity arrival at a depth of ~120 km from the eastern edge of the Altiplano to the Subandean zone. We suggest this may be a good candidate for the base of the CAP lithosphere. In addition, above this depth the mantle is strongly layered, suggesting that there is not a simple high velocity mantle lithosphere associated with the continental lithosphere underthrusting the Andean orogen from the east.
Impact of wave propagation delay on latency in optical communication systems
NASA Astrophysics Data System (ADS)
Kawanishi, Tetsuya; Kanno, Atsushi; Yoshida, Yuki; Kitayama, Ken-ichi
2012-12-01
Latency is an important figure to describe performance of transmission systems for particular applications, such as data transfer for earthquake early warning, transaction for financial businesses, interactive services such as online games, etc. Latency consists of delay due to signal processing at nodes and transmitters, and of signal propagation delay due to propagation of electromagnetic waves. The lower limit of the latency in transmission systems using conventional single mode fibers (SMFs) depends on wave propagation speed in the SMFs which is slower than c. Photonic crystal fibers, holly fibers and large core fibers can have low effective refractive indices, and can transfer light faster than in SMFs. In free-space optical systems, signals propagate with the speed c, so that the latency could be smaller than in optical fibers. For example, LEO satellites would transmit data faster than optical submarine cables, when the transmission distance is longer than a few thousand kilometers. This paper will discuss combination of various transmission media to reduce negative impact of the latency, as well as applications of low-latency systems.
NASA Astrophysics Data System (ADS)
Sereika, Raimundas; Bondarenka, Vladimiras; Rimeika, Romualdas; Sereika, Albertas; ?iplys, Daumantas
2014-11-01
The impact of ambient humidity on surface acoustic wave (SAW) propagation in the structure consisting of vanadium pentoxide xerogel (V2O5nH2O) layer deposited on a piezoelectric lithium niobate (LiNbO3) substrate has been studied. Thin V2O5nH2O layers were synthesized using sol-gel method and employed as humidity sensing materials. Freshly prepared layer drastically reduced the transmitted SAW signal, which later increased with time reaching saturation after more than 120 h at the level well below the free-surface value. The experimental observations of SAW behaviour were discussed and found related to the variations in resistance and dielectric permittivity of the V2O5nH2O.
Estienne, Benoit; Bernevig, B. Andrei; Santachiara, Raoul
2010-11-15
We consider the quasihole wave functions of the non-Abelian Read-Rezayi quantum-Hall states which are given by the conformal blocks of the minimal model WA{sub k-1}(k+1,k+2) of the WA{sub k-1} algebra. By studying the degenerate representations of this conformal field theories, we derive a second-order differential equation satisfied by a general many-quasihole wave function. We find a duality between the differential equations fixing the electron and quasihole wave functions. They both satisfy the Laplace-Beltrami equation. We use this equation to obtain an analytic expression for the generic wave function with one excess flux. These results also apply to the more general models WA{sub k-1}(k+1,k+r) corresponding to the recently introduced Jack states.
Impact of atmospheric convectively coupled equatorial Kelvin waves on upper ocean variability
NASA Astrophysics Data System (ADS)
Baranowski, Dariusz B.; Flatau, Maria K.; Flatau, Piotr J.; Matthews, Adrian J.
2016-03-01
Convectively coupled Kelvin waves (CCKWs) are atmospheric weather systems that propagate eastward along the equatorial wave guide with phase speeds between 11 and 14 m s-1. They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which ocean-atmosphere interactions play a vital role. Hence, ocean-atmosphere interactions within CCKWs may be important for MJO development and prediction and for tropical climate, in general. Although the atmospheric structure of CCKWs has been well studied, their impact on the underlying ocean is unknown. In this paper, the ocean-atmosphere interactions in CCKWs are investigated by a case study from November 2011 during the CINDY/DYNAMO field experiment, using in situ oceanographic measurements from an ocean glider. The analysis is then extended to a 15 year period using precipitation data from the Tropical Rainfall Measuring Mission and surface fluxes from the TropFlux analysis. A methodology is developed to calculate trajectories of CCKWs. CCKW events are strongly controlled by the MJO, with twice as many CCKWs observed during the convectively active phase of the MJO compared to the suppressed phase. Coherent ocean-atmosphere interaction is observed during the passage of a CCKW, which lasts approximately 4 days at any given longitude. Surface wind speed and latent heat flux are enhanced, leading to a transient suppression of the diurnal cycle of sea surface temperature (SST) and a sustained decrease in bulk SST of 0.1°C. Given that a typical composite mean MJO SST anomaly is of the order of 0.3°C, and more than one CCKW can occur during the active phase of a single MJO event, the oceanographic impact of CCKWs is of major importance to the MJO cycle.
Bannister, S.; Bryan, C.J.; Bibby, H.M.
2004-01-01
The Taupo Volcanic Zone (TVZ), New Zealand is a region characterized by very high magma eruption rates and extremely high heat flow, which is manifest in high-temperature geothermal waters. The shear wave velocity structure across the region is inferred using non-linear inversion of receiver functions, which were derived from teleseismic earthquake data. Results from the non-linear inversion, and from forward synthetic modelling, indicate low S velocities at ???6- 16 km depth near the Rotorua and Reporoa calderas. We infer these low-velocity layers to represent the presence of high-level bodies of partial melt associated with the volcanism. Receiver functions at other stations are complicated by reverberations associated with near-surface sedimentary layers. The receiver function data also indicate that the Moho lies between 25 and 30 km, deeper than the 15 ?? 2 km depth previously inferred for the crust-mantle boundary beneath the TVZ. ?? 2004 RAS.
Standing waves of a weakly coupled Schrödinger system with distinct potential functions
NASA Astrophysics Data System (ADS)
Wang, Jun; Shi, Junping
2016-01-01
The standing wave solutions of a weakly coupled nonlinear Schrödinger system with distinct trapping potential functions in RN (1 ≤ N ≤ 3) are considered. This type of system arises from models in Bose-Einstein condensates theory and nonlinear optics. The existence of a positive ground state solution is shown when the coupling constant is larger than a sharp threshold value, which is explicitly defined in terms of potential functions and system parameters. It is also shown that such solutions concentrate near the minimum points of potential functions, and multiple positive concentration solutions exist when the topological structure of the set of minimum points satisfies certain condition. Variational approach is used for the existence and concentration of positive solutions.
Efficient calculation of 1-D periodic Green's functions for leaky-wave applications.
Baccarelli, Paolo; Johnson, William Arthur; Paulotto, Simone; Jackson, David R.; Wilton, Donald R.; Galli, A.; Valero, G.; Celepcikay, F. T.
2010-08-01
In this paper an approach is described for the efficient computation of the mixed-potential scalar and dyadic Green's functions for a one-dimensional periodic (periodic along x direction) array of point sources embedded in a planar stratified structure. Suitable asymptotic extractions are performed on the slowly converging spectral series. The extracted terms are summed back through the Ewald method, modified and optimized to efficiently deal with all the different terms. The accelerated Green's functions allow for complex wavenumbers, and are thus suitable for application to leaky-wave antennas analysis. Suitable choices of the spectral integration paths are made in order to account for leakage effects and the proper/improper nature of the various space harmonics that form the 1-D periodic Green's function.
Regularized quadratic cost-function for integrating wave-front gradient fields.
Villa, Jesús; Rodríguez, Gustavo; Ivanov, Rumen; González, Efrén
2016-05-15
From the Bayesian regularization theory we derive a quadratic cost-function for integrating wave-front gradient fields. In the proposed cost-function, the term of conditional distribution uses a central-differences model to make the estimated function well consistent with the observed gradient field. As will be shown, the results obtained with the central-differences model are superior to the results obtained with the backward-differences model, commonly used in other integration techniques. As a regularization term we use an isotropic first-order differences Markov Random-Field model, which acts as a low-pass filter reducing the errors caused by the noise. We present simulated and real experiments of the proposal applied in the Foucault test, obtaining good results. PMID:27176991
Spatial impacts of heat waves in mortality. Evaluating current risks and future threats
NASA Astrophysics Data System (ADS)
Andrade, H.; Canario, P.; Nogueira, H.
2009-09-01
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.
Antidepressants Impact Connexin 43 Channel Functions in Astrocytes.
Jeanson, Tiffany; Pondaven, Audrey; Ezan, Pascal; Mouthon, Franck; Charvériat, Mathieu; Giaume, Christian
2015-01-01
Glial cells, and in particular astrocytes, are crucial to maintain neuronal microenvironment by regulating energy metabolism, neurotransmitter uptake, gliotransmission, and synaptic development. Moreover, a typical feature of astrocytes is their high expression level of connexins, a family of membrane proteins that form gap junction channels allowing intercellular exchanges and hemichannels that provide release and uptake pathways for neuroactive molecules. Interestingly, several studies have revealed unexpected changes in astrocytes from depressive patients and rodent models of depressive-like behavior. Moreover, changes in the expression level of the astroglial connexin 43 (Cx43) have been reported in a depressive context. On the other hand, antidepressive drugs have also been shown to impact the expression of this connexin in astrocytes. However, so far there is little information concerning the functional consequence of these changes, i.e., the status of gap junctional communication and hemichannel activity in astrocytes exposed to antidepressants. In the present work we focused our attention on the action of seven antidepressants from four different therapeutic classes and tested their effects on Cx43 expression and on the two connexin-based channels functions studied in cultured astrocytes. We here report that when used at non-toxic and clinically relevant concentrations they have no effects on Cx43 expression but differential effects on Cx43 gap junction channels. Moreover, all tested antidepressants inhibit Cx43 hemichannel with different efficiency depending on their therapeutic classe. By studying the impact of antidepressants on the functional status of astroglial connexin channels, contributing to dynamic neuroglial interactions, our observations should help to better understand the mechanism by which these drugs provide their effect in the brain. PMID:26778961
Antidepressants Impact Connexin 43 Channel Functions in Astrocytes
Jeanson, Tiffany; Pondaven, Audrey; Ezan, Pascal; Mouthon, Franck; Charvériat, Mathieu; Giaume, Christian
2016-01-01
Glial cells, and in particular astrocytes, are crucial to maintain neuronal microenvironment by regulating energy metabolism, neurotransmitter uptake, gliotransmission, and synaptic development. Moreover, a typical feature of astrocytes is their high expression level of connexins, a family of membrane proteins that form gap junction channels allowing intercellular exchanges and hemichannels that provide release and uptake pathways for neuroactive molecules. Interestingly, several studies have revealed unexpected changes in astrocytes from depressive patients and rodent models of depressive-like behavior. Moreover, changes in the expression level of the astroglial connexin 43 (Cx43) have been reported in a depressive context. On the other hand, antidepressive drugs have also been shown to impact the expression of this connexin in astrocytes. However, so far there is little information concerning the functional consequence of these changes, i.e., the status of gap junctional communication and hemichannel activity in astrocytes exposed to antidepressants. In the present work we focused our attention on the action of seven antidepressants from four different therapeutic classes and tested their effects on Cx43 expression and on the two connexin-based channels functions studied in cultured astrocytes. We here report that when used at non-toxic and clinically relevant concentrations they have no effects on Cx43 expression but differential effects on Cx43 gap junction channels. Moreover, all tested antidepressants inhibit Cx43 hemichannel with different efficiency depending on their therapeutic classe. By studying the impact of antidepressants on the functional status of astroglial connexin channels, contributing to dynamic neuroglial interactions, our observations should help to better understand the mechanism by which these drugs provide their effect in the brain. PMID:26778961
Bobrov, V B; Trigger, S A; van Heijst, G J F; Schram, P P J M
2010-07-01
On the basis of the stationary Schrödinger equation, the virial theorem in an inhomogeneous external field for the canonical ensemble is proved. It is shown that the difference in the form of virial theorem is conditioned by the value of the wave-function derivative on the surface of the volume, surrounding the system under consideration. The stress tensor in such a system is determined by the average values of the wave-function space derivatives. PMID:20866550
Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas
Alducin, M.; Nagy, I.
2003-07-01
Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.
Computation of the drift velocity of spiral waves using response functions
NASA Astrophysics Data System (ADS)
Biktasheva, I. V.; Barkley, D.; Biktashev, V. N.; Foulkes, A. J.
2010-06-01
Rotating spiral waves are a form of self-organization observed in spatially extended systems of physical, chemical, and biological nature. In the presence of a small perturbation, the spiral wave’s center of rotation and fiducial phase may change over time, i.e., the spiral wave drifts. In linear approximation, the velocity of the drift is proportional to the convolution of the perturbation with the spiral’s response functions, which are the eigenfunctions of the adjoint linearized operator corresponding to the critical eigenvalues λ=0,±iω . Here, we demonstrate that the response functions give quantitatively accurate prediction of the drift velocities due to a variety of perturbations: a time dependent, periodic perturbation (inducing resonant drift); a rotational symmetry-breaking perturbation (inducing electrophoretic drift); and a translational symmetry-breaking perturbation (inhomogeneity induced drift) including drift due to a gradient, stepwise, and localized inhomogeneity. We predict the drift velocities using the response functions in FitzHugh-Nagumo and Barkley models, and compare them with the velocities obtained in direct numerical simulations. In all cases good quantitative agreement is demonstrated.
From ground-state densities to entangled wave functions: an exploration for the Hubbard model
NASA Astrophysics Data System (ADS)
Capelle, Klaus
2015-03-01
The fundamental Hohenberg-Kohn theorem of density-functional theory (DFT) guarantees that, in principle, all information about a many-body system is contained in it ground-state density. Most effort in DFT is thus directed at finding ways to reliably calculate this density and to extract useful information from it. Quantum-information theory (QIT), on the other hand, is little concerned with ground-state densities, focusing instead on wave functions and density matrices, with a view on exploiting entangled states in information processing. In spite of these different philosophies, many connections exist between both approaches. In this talk, I review of how some of these connections have been discovered and quantified in the context of the Hubbard model: (i) DFT calculations for a model Hamiltonian serve to relate the entanglement entropy to phase transitions; (ii) a local-density-type approximation can be used to calculate the entanglement entropy of spatially inhomogeneous systems, such as cold atoms in optical traps and large superlattices, where traditional numerical methods encounter difficulties; (iii) a combination of DFT with Bethe-Ansatz techniques allows one to calculate the values of system-specific parameters in expressions for the block-block entanglement that remain undetermined in scaling approaches; (iv) the construction of suitable metrics shines light on how the Hohenberg-Kohn theorem relates densities and wave functions for different systems.
Oliveira, Micael J T; Mignolet, Benoit; Kus, Tomasz; Papadopoulos, Theodoros A; Remacle, F; Verstraete, Matthieu J
2015-05-12
Attosecond electron dynamics in small- and medium-sized molecules, induced by an ultrashort strong optical pulse, is studied computationally for a frozen nuclear geometry. The importance of exchange and correlation effects on the nonequilibrium electron dynamics induced by the interaction of the molecule with the strong optical pulse is analyzed by comparing the solution of the time-dependent Schrödinger equation based on the correlated field-free stationary electronic states computed with the equationof-motion coupled cluster singles and doubles and the complete active space multi-configurational self-consistent field methodologies on one hand, and various functionals in real-time time-dependent density functional theory (TDDFT) on the other. We aim to evaluate the performance of the latter approach, which is very widely used for nonlinear absorption processes and whose computational cost has a more favorable scaling with the system size. We focus on LiH as a toy model for a nontrivial molecule and show that our conclusions carry over to larger molecules, exemplified by ABCU (C10H19N). The molecules are probed with IR and UV pulses whose intensities are not strong enough to significantly ionize the system. By comparing the evolution of the time-dependent field-free electronic dipole moment, as well as its Fourier power spectrum, we show that TD-DFT performs qualitatively well in most cases. Contrary to previous studies, we find almost no changes in the TD-DFT excitation energies when excited states are populated. Transitions between states of different symmetries are induced using pulses polarized in different directions. We observe that the performance of TD-DFT does not depend on the symmetry of the states involved in the transition. PMID:26894253
Symmetric tensor decomposition description of fermionic many-body wave functions.
Uemura, Wataru; Sugino, Osamu
2012-12-21
The configuration interaction (CI) is a versatile wave function theory for interacting fermions, but it involves an extremely long CI series. Using a symmetric tensor decomposition method, we convert the CI series into a compact and numerically tractable form. The converted series encompasses the Hartree-Fock state in the first term and rapidly converges to the full-CI state, as numerically tested by using small molecules. Provided that the length of the symmetric tensor decomposition CI series grows only moderately with the increasing complexity of the system, the new method will serve as one of the alternative variational methods to achieve full CI with enhanced practicability. PMID:23368456
Evaluation of partial widths and branching ratios from resonance wave functions
Goldzak, Tamar; Gilary, Ido; Moiseyev, Nimrod
2010-11-15
A quantum system in a given resonance state has different open channels for decay. Partial widths are the decay rates of the resonance (metastable) state into the different open channels. Here we present a rigorous derivation of the partial widths from the solution of a time-dependent Schroedinger equation with outgoing boundary conditions. We show that the sum of the partial widths obtained from the resonance wave function is equal to the total width. The difference with respect to previous studies on partial widths and branching ratios is discussed.
Models of spontaneous wave function collapse: what they are, and how they can be tested
NASA Astrophysics Data System (ADS)
Bassi, Angelo
2016-03-01
There are few proposals, which explicitly allow for (experimentally testable) deviations from standard quantum theory. Collapse models are among the most-widely studied proposals of this kind. The Schrödinger equation is modified by including nonlinear and stochastic terms, which describe the collapse of the wave function in space. These spontaneous collapses are rare for microscopic systems, hence their quantum properties are left almost unaltered. On the other hand, collapses become more and more frequent, the larger the object, to the point that macroscopic superpositions are rapidly suppressed. The main features of collapse models will be reviewed. An update of the most promising experimental tests will be presented.
Extracting elements of molecular structure from the all-particle wave function
Matyus, Edit; Reiher, Markus; Hutter, Juerg; Mueller-Herold, Ulrich
2011-11-28
Structural information is extracted from the all-particle (non-Born-Oppenheimer) wave function by calculating radial and angular densities derived from n-particle densities. As a result, one- and two-dimensional motifs of classical molecular structure can be recognized in quantum mechanics. Numerical examples are presented for three- (H{sup -}, Ps{sup -}, H{sub 2}{sup +}), four- (Ps{sub 2}, H{sub 2}), and five-particle (H{sub 2}D{sup +}) systems.
Convergence to equilibrium for solutions of an abstract wave equation with general damping function
NASA Astrophysics Data System (ADS)
Bárta, Tomáš; Fašangová, Eva
2016-02-01
We prove convergence to a stationary solution as time goes to infinity of solutions to abstract nonlinear wave equation with general damping term and gradient nonlinearity, provided the trajectory is precompact. The energy is supposed to satisfy a Kurdyka-Łojasiewicz gradient inequality. Our aim is to formulate conditions on the function g as general as possible when the damping is a scalar multiple of the velocity, and this scalar depends on the norm of the velocity, g (|ut |)ut. These turn out to be estimates and a coupling condition with the energy but not global monotonicity. When the damping is more general, we need an angle condition.
Thomas, Edward Jr.; Williams, Jeremiah
2006-05-15
Two-dimensional particle image velocimetry (2D-PIV) techniques have been applied to dusty plasmas for the past 5 years. During that time, 2D-PIV has been used to provide detailed measurements of microparticle transport in dusty plasmas. However, a measurement of the third velocity vector direction is necessary to fully understand the microparticle transport. In this paper, stereoscopic particle image velocimetry (stereo-PIV) is used as a technique for obtaining all three-velocity vector components. This paper discusses the application of stereo-PIV techniques to measurements of dust acoustic waves and velocity space distribution functions in dusty plasmas.
NASA Astrophysics Data System (ADS)
Yasui, M.; Matsumoto, E.; Arakawa, M.; Matsue, K.; Kobayashi, N.
2014-07-01
Introduction: A seismic wave survey is a direct method to investigate the sub-surface structures of solid bodies, so we measured and analyzed these seismic waves propagating through these interiors. Earthquake and Moonquake are the only two phenomena that have been observed to explore these interiors until now, while the future surveys on the other bodies, (solid planets and/or asteroids) are now planned. To complete a seismic wave survey during the mission period, an artificial method that activates the seismic wave is necessary and one candidate is a projectile collision on the target body. However, to utilize the artificial seismic wave generated on the target body, the relationship between the impact energy and the amplitude and the decay process of the seismic wave should be examined. If these relationships are clarified, we can estimate the required sensitivity of seismometers installed on the target body and the possible distance from the seismic origin measurable for the seismometer. Furthermore, if we can estimate the impact energy from the observed seismic wave, we expect to be able to estimate the impact flux of impactors that collided on the target body. McGarr et al. (1969) did impact experiments by using the lexan projectile and two targets, quartz sand and sand bonded by epoxy cement, at 0.8-7 km/s. They found a difference of seismic wave properties between the two targets, and calculated the conversion efficiency to discuss the capability of detection of seismic waves on the Moon. However, they did not examine the excitation and propagation properties of the seismic waves in detail. In this study, we carried out impact experiments in the laboratory to observe the seismic waves by accelerometers, and examined the effects of projectile properties on the excitation and propagation properties of the seismic waves. Experimental methods: We made impact experiments by using a one-stage gas gun at Kobe University. Projectiles were a polycarbonate cylinder with a diameter of 10 mm and a height of 10 mm, and stainless steel and alumina balls with a diameter of 3 mm. The stainless steel and alumina projectiles were accelerated with a sabot made of polyethylene. The impact velocity was from 20 to 100 m/s. The target was a non-cohesive glass bead with a mean particle diameter of 200 μ m prepared by putting the particles into a container with a diameter of 300 mm and a height of 100 mm, up to 80 mm depth. The target porosity was about 40%. A chamber that we set the target in was evacuated below 1000 Pa. Three accelerometers (response frequency < 10 kHz) were set on the target surface at different distances from the impact point. The observed seismic waves were recorded on a data logger (A/D conversion rate 100 kHz). Experimental results: First, we examined the propagation velocity of the seismic wave by using the traveling time from the impact point to the site of the accelerometer, then the impact velocity was obtained to be 105 ± 15 m/s. Next, we discovered that the maximum acceleration, g_max, had a good relationship to the normalized distance, x/R (x: distance from impact point, R: crater radius) and it was fitted by the following equation, g_max=268(x/R)^{-2.8}, irrespective of projectile types. These results mean that the seismic wave attenuates with a similar waveform scaled by the crater radius on the same target. The duration keeping the maximum acceleration was measured to have a half width of g_max peak on the waveform, and it was estimated to be ˜0.3 ms. This value is almost consistent with the penetration time of projectiles estimated by the model proposed by Niimi et al. (2011). McGarr et al. (1969) studied the momentum conversion efficiency from the projectile momentum to the target momentum transferred by the seismic wave and obtained it as the ratio of the momentum calculated by the particle motion, I, to the projectile momentum, I_p. In our study, the I/I_p was obtained to be 0.23-1.56. This range was almost consistent with that of McGarr et al. (1969), 0.39-1.62. We can conclude that I/I_p is independent of the impact velocity. Implications for planetary exploration: According to the previous results, we can discuss the sensitivity of the seismometer to detect the seismic wave induced by an artificial impactor on asteroids. We calculated the maximum acceleration on asteroids with two different sizes, such as the sizes of Eros and 1999JU3, by assuming that the projectile made of copper with a mass of 2 kg impacted at 2 km/s. In this calculation, we used the crater scaling law and the attenuation equation of g_max obtained in our study. As a result, the seismometer could detect the seismic wave only around the crater cavity on an Eros-sized asteroid while it could detect the wave globally on a 1999JU3-sized asteroid.
NASA Astrophysics Data System (ADS)
Gibbons, M. J.
1988-12-01
The impact of wave exposure on the meiofaunal communities colonising Gelidium pristoides, was examined on five shores around False Bay, South Africa. Under conditions of constant algal structure and mass, and in tufts with similar epiphyte and sediment loads, exposure had a profound impact on meiofaunal communities. Algae on sheltered shores supported significantly greater numbers of animals in the size range 63-280 μm (predominantly copepods, copepod nauplii and ostracods), while those on exposed shores supported a greater number of amphipods and bivalves. Total meiofaunal biomass per tuft remained constant irrespective of shore type. Differences between shores are discussed in terms of algal structure and animal size and morphology. Gelidium tufts are open-plan and offer little resistance to water movement; as the frond diameter is wider than the meiofauna are long, small animals are likely to be flushed more easily from exposed than sheltered shores. Differences in the abundance of permanent meiofauna between shores may, however, reflect ifferences in the organic content of sediments, although this was not examined. It is also suggested that meiofaunal communities on plants from different shores are influenced by the total algal and macrofaunal standing stocks, which act as banks of meiofauna and influence the regularity and magnitude of immigration. Extrapolating these data to the whole shore indicates that while the biomass of meiofauna may be greater on exposed than sheltered shores, the proportional contribution of meiofauna to total secondary production is greater under more sheltered conditions.
The ecology of seamounts: structure, function, and human impacts.
Clark, Malcolm R; Rowden, Ashley A; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I; Rogers, Alex D; O'Hara, Timothy D; White, Martin; Shank, Timothy M; Hall-Spencer, Jason M
2010-01-01
In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research. PMID:21141665
Impacts of Oxidative Stress and Antioxidants on Semen Functions
Bansal, Amrit Kaur; Bilaspuri, G. S.
2011-01-01
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
The Ecology of Seamounts: Structure, Function, and Human Impacts
NASA Astrophysics Data System (ADS)
Clark, Malcolm R.; Rowden, Ashley A.; Schlacher, Thomas; Williams, Alan; Consalvey, Mireille; Stocks, Karen I.; Rogers, Alex D.; O'Hara, Timothy D.; White, Martin; Shank, Timothy M.; Hall-Spencer, Jason M.
2010-01-01
In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.
NASA Astrophysics Data System (ADS)
Katsuki, Hiroyuki; Ohmori, Kenzo; Horie, Toru; Yanagi, Hisao; Ohmori, Kenji
2015-09-01
Solid parahydrogen, which is known to have an exceptionally long vibrational coherence lifetime as a molecular solid, offers an ideal testbed to perform coherent control experiments in the condensed phase. Here we demonstrate the spatial manipulation and visualization of the relative phase of vibrational wave functions in solid parahydrogen. Spatial distribution of vibrational excitation is generated by femtosecond impulsive Raman excitation. It is shown that the imprinted initial phase can be manipulated by wave-front modulation of the excitation laser pulses with a spatial light modulator. An interferometric measurement is used to convert the spatial phase distribution of the vibrational wave functions to the amplitude distribution. We have confirmed that the spatial profile of the scattered anti-Stokes pulse reveals the spatial phase distribution of the wave functions. The read-and-write scheme demonstrated in this experiment is applicable to a broad range of Raman memory systems accessible by Λ -type transitions.
Characterization of a setup to test the impact of high-amplitude pressure waves on living cells.
Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O
2014-01-01
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
Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells
NASA Astrophysics Data System (ADS)
Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.
2014-01-01
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.
Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells
Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.
2014-01-01
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
Finasteride-Its Impact on Sexual Function and Prostate Cancer
Anitha, B; Inamadar, Arun C; Ragunatha, S
2009-01-01
Finasteride, a specific and competitive inhibitor of 5α-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
NASA Astrophysics Data System (ADS)
Sadoff, N.; Weber, S.; Zell, E. R.; de Sherbinin, A. M.
2014-12-01
Climate-induced heat waves have been increasing globally in the past 5-10 years and are projected to continue increasing throughout the 21st century. In urban areas, heat waves are exacerbated by the non-climate stressor of urban heat islands (UHIs). The vulnerability of a city's population to heat waves reflects exposure to extreme heat events, sensitivity of the population to impacts, such as adverse health effects, and adaptive capacity to prepare for and respond to heat waves. Socially and economically vulnerable populations are especially at risk to the impacts of heat waves, due to increasing energy costs, air pollution, and heat-related illness and mortality. NASA earth science datasets, combined with socioeconomic data, can be used to create indicators that characterize vulnerability to urban heat events and address the effectiveness of adaptation measures designed to reduce local temperatures. The indicator development process should include engagement from local stakeholders and end users from the onset to ensure local relevance and, ultimately, indicator uptake and sustainability. This presentation will explore the process of working with urban stakeholders in Philadelphia to develop a set of policy-relevant, interdisciplinary vulnerability indicators focused on extreme heat events in urban areas. Ambient and land surface temperature, land cover classifications, NDVI, and US Census data are used to create a basket of indicators that reflect urban heat wave duration and intensity, UHI exposure, socioeconomic vulnerability, and adaptation effectiveness. These indicators can be assessed at the city level and also comparatively among different parts of a city to help quantify and track heat wave impacts on vulnerable populations and the effectiveness of adaptation measures.
System and Method for Measuring the Transfer Function of a Guided Wave Device
NASA Technical Reports Server (NTRS)
Froggatt, Mark E. (Inventor); Erdogan, Turan (Inventor)
2002-01-01
A method/system are provided for measuring the NxN scalar transfer function elements for an N-port guided wave device. Optical energy of a selected wavelength is generated at a source and directed along N reference optical paths having N reference path lengths. Each reference optical path terminates in one of N detectors such that N reference signals are produced at the N detectors. The reference signals are indicative of amplitude, phase and frequency of the optical energy carried along the N reference optical paths. The optical energy from the source is also directed to the N-ports of the guided wave device and then on to each of the N detectors such that N measurement optical paths are defined between the source and each of the N detectors. A portion of the optical energy is modified in terms of at least one of the amplitude and phase to produce N modified signals at each of the N detectors. At each of the N detectors, each of the N modified signals is combined with a corresponding one of the N reference signals to produce corresponding N combined signals at each of the N detectors. A total of N(sup 2) measurement signals are generated by the N detectors. Each of the N(sup 2) measurement signals is sampled at a wave number increment (Delta)k so that N(sup 2) sampled signals are produced. The NxN transfer function elements are generated using the N(sup 2) sampled signals. Reference and measurement path length constraints are defined such that the N combined signals at each of the N detectors are spatially separated from one another in the time domain.
DNA--a molecule in search of additional functions: recipient of pool wave emissions? A hypothesis.
Doerfler, Walter
2010-09-01
Almost the entire nucleotide sequence of human DNA is functionally unaccounted for, although large parts of the human genome are transcribed. The genes, as defined by current molecular biology, comprise about 1.5-2% of the DNA molecule. It is proposed that DNA encodes additional, hitherto unrecognized functions. In this discussion, the total information inside and outside the universe we live in is termed the pool or the sum total, known or unknown, of all laws, matter, energy, concepts and events. In a hypothetical model, a Gedankenexperiment, it is suggested that the total of all information emits pool waves of an unknown physical nature. They could be related to black energy or have completely different qualities. The designation pool waves should not imply any similarity to electromagnetism. Further, DNA is suggested to have the capability of interacting with the pool waves and thus permit humans - to some partly genetically determined and yet very limited extent - to perceive information from the pool. Pool emissions might be one of the forces that have been instrumental in and are still driving evolution from simple oligonucleotides to DNA with ever more complex recipient capacities. It will be a major challenge for researchers in the field to unravel these and less hypothetical undetected coding principles in DNA. It is uncertain whether the current trend to search the available DNA sequences with ever more refined computer technology on the basis of our present understanding of biology will detect unknown coding systems. For molecular medicine, research into the genetics of the most common human diseases could profit from the elucidation of presently still ephemeral codes in human DNA. Young scientists with a proven record of original research deserve support for the pursuit of unconventional ideas. This concept of granting priorities will be of the utmost importance in advancing the field beyond current concepts in molecular biology. PMID:20356684
NASA Astrophysics Data System (ADS)
Slob, E. C.; Grobbe, N.
2014-12-01
The theory of coupled elastic waves and electromagnetic fields in porous media exists for two decades. Several modeling codes have been developed and some field work has been carried out with mixed success. Modeling the so-called electroseismic and seismo-electromagnetic wavefields is tricky because of the strong elastic fields generated by mechanical sources and strong electromagnetic fields generated by electromagnetic sources, while the coupled fields have relatively small amplitudes. A second difficulty is the fact that the elastic field is essentially a wavefield, while the electromagnetic field is a diffusive field. The slow P-wave is usually also a diffusive field depending on the frequency bandwidth of the data. On the other hand, for porous soils and rocks, laboratory measurements have been carried out to experimentally validate the current theoretical model and to some extent this has been successful. To be able to understand measured data it is crucially important that we have good control on the accuracy of modeled data. Today we don't have this control, which makes it hard to judge the quality of the modeled data and trust the experimental validation of the theory. It is therefore important that exact solutions are found to validate modeling codes in simple configurations. These modeling codes can then numerically validate the theory by matching the results obtained in laboratory or field experiments. The simplest configuration is the homogeneous space and we show exact solutions for the governing equations for point sources and point receivers. These Green's functions are obtained for any type of point source and any type of receiver. We reduce the coupled equations to two scalar equations for the electric field and the particle velocity vectors. Solutions for longitudinal and transverse waves are obtained separately and these are combined to obtain the Green's functions for the electric field and the particle velocity, from which the solutions for all other fields are found. We show numerical examples of the fields that can be measured in the field.
Phase transitions of energy and wave functions and bound states in the continuum
NASA Astrophysics Data System (ADS)
Zhang, Xiao; Wei, Chaozhen; Liu, Yingming; Luo, Maokang
2016-04-01
This paper studies a particle subjected to an infinite potential well in the circumstance of a fractional dimensional Lévy path. To obtain analytic expression for the wave functions and energy levels, we introduce the fractional corresponding operator and a generalized de Moivre's theorem. Phase transitions of the energy and wave functions are found when the Lévy path dimension changes from integer to noninteger in nature. More importantly, we demonstrate the existence of stable bound states in the continuum in a simple potential. The results predict a phenomenon in which all bound states energy levels of the particle are continuous and the particle remains in bound states. This phenomenon can be demonstrated that this is a characteristic phenomenon of a fractional system. This phenomenon provides both an a priori criterion for theoretically describing an unknown quantum system with fractional derivatives and a sufficient condition for verifying the preparation of a fractional quantum system in experiment. Finally, we compare our results for fractional quantum systems with the existing results and explain the cause of the reported phenomenon.
Is a system's wave function in one-to-one correspondence with its elements of reality?
Colbeck, Roger; Renner, Renato
2012-04-13
Although quantum mechanics is one of our most successful physical theories, there has been a long-standing debate about the interpretation of the wave function--the central object of the theory. Two prominent views are that (i) it corresponds to an element of reality, i.e., an objective attribute that exists before measurement, and (ii) it is a subjective state of knowledge about some underlying reality. A recent result [M. F. Pusey, J. Barrett, and T. Rudolph, arXiv:1111.3328] has placed the subjective interpretation into doubt, showing that it would contradict certain physically plausible assumptions, in particular, that multiple systems can be prepared such that their elements of reality are uncorrelated. Here we show, based only on the assumption that measurement settings can be chosen freely, that a system's wave function is in one-to-one correspondence with its elements of reality. This also eliminates the possibility that it can be interpreted subjectively. PMID:22587234
Ergodicity breaking and wave-function statistics in disordered interacting systems
De Luca, Andrea
2014-08-20
We present the study of the structure of many-body eigenfunctions in a one-dimensional disordered spin chain. We discuss the choice of an appropriate basis in the Hilbert space, where the problem can be seen as an Anderson model defined on a high-dimensional non-trivial graph, determined by the many-body Hamiltonian. The comparison with the usual behavior of wave-functions in finite dimensional Anderson localization allows us to put in light the main differences of the many-body case. At high disorder, the typical eigenfunctions do not seem to localize though they occupy a infinitesimal portion of the Hilbert space in the thermodynamic limit. We perform a detailed analysis of the distribution of the wave-function coefficients and their peculiar scaling in the small and large disorder phase. We propose a criterion to identify the position of the transition by looking at the long tails of these distributions. The results coming from exact diagonalization show signs of breaking of ergodicity when the disorder reaches a critical value that agrees with the estimation of the many-body localization transition in the same model.
Crustal Structure of Iraq from Receiver Functions and Surface Wave Dispersion
Gok, R; Mahdi, H; Al-Shukri, H; Rodgers, A J
2006-08-31
We report the crustal structure of Iraq, located in the northeastern Arabian plate, estimated by joint inversion of P-wave receiver functions and surface wave group velocity dispersion. Receiver functions were computed from teleseismic recordings at two temporary broadband seismic stations in Mosul (MSL) and Baghdad (BHD), separated by approximately 360 km. Group velocity dispersion curves at the sites were derived from continental-scale tomography of Pasyanos (2006). The inversion results show that the crustal thicknesses are 39 km at MSL and 43 km at BHD. Both sites reveal low velocity surface layers consistent with sedimentary thickness of about 3 km at station MSL and 7 km at BHD, agreeing well with the existing models. Ignoring the sediments, the crustal velocities and thicknesses are remarkably similar between the two stations, suggesting that the crustal structure of the proto-Arabian Platform in northern Iraq was uniform before subsidence and deposition of the sediments in the Cenozoic. Deeper low velocity sediments at BHD are expected to result in higher ground motions for earthquakes.
Pixel level optical-transfer-function design based on the surface-wave-interferometry aperture
Zheng, Guoan; Wang, Yingmin; Yang, Changhuei
2010-01-01
The design of optical transfer function (OTF) is of significant importance for optical information processing in various imaging and vision systems. Typically, OTF design relies on sophisticated bulk optical arrangement in the light path of the optical systems. In this letter, we demonstrate a surface-wave-interferometry aperture (SWIA) that can be directly incorporated onto optical sensors to accomplish OTF design on the pixel level. The whole aperture design is based on the bull’s eye structure. It composes of a central hole (diameter of 300 nm) and periodic groove (period of 560 nm) on a 340 nm thick gold layer. We show, with both simulation and experiment, that different types of optical transfer functions (notch, highpass and lowpass filter) can be achieved by manipulating the interference between the direct transmission of the central hole and the surface wave (SW) component induced from the periodic groove. Pixel level OTF design provides a low-cost, ultra robust, highly compact method for numerous applications such as optofluidic microscopy, wavefront detection, darkfield imaging, and computational photography. PMID:20721038
Problems and aspects of energy-driven wave-function collapse models
Pearle, Philip
2004-04-01
Four problematic circumstances are considered, involving models which describe dynamical wave-function collapse toward energy eigenstates, for which it is shown that wave-function collapse of macroscopic objects does not work properly. In one case, a common particle position measuring situation, the apparatus evolves to a superposition of macroscopically distinguishable states (does not collapse to one of them as it should) because each such particle/apparatus/environment state has precisely the same energy spectrum. Second, assuming an experiment takes place involving collapse to one of two possible outcomes which is permanently recorded, it is shown in general that this can only happen in the unlikely case that the two apparatus states corresponding to the two outcomes have disjoint energy spectra. Next, the progressive narrowing of the energy spectrum due to the collapse mechanism is considered. This has the effect of broadening the time evolution of objects as the universe evolves. Two examples, one involving a precessing spin, the other involving creation of an excited state followed by its decay, are presented in the form of paradoxes. In both examples, the microscopic behavior predicted by standard quantum theory is significantly altered under energy-driven collapse, but this alteration is not observed by an apparatus when it is included in the quantum description. The resolution involves recognition that the state vector describing the apparatus does not collapse, but evolves to a superposition of macroscopically different states.
Gutzwiller wave function for finite systems: superconductivity in the Hubbard model
NASA Astrophysics Data System (ADS)
Tomski, Andrzej; Kaczmarczyk, Jan
2016-05-01
We study the superconducting phase of the Hubbard model using the Gutzwiller variational wave function (GWF) and the recently proposed diagrammatic expansion technique (DE-GWF). The DE-GWF method works on the level of the full GWF and in the thermodynamic limit. Here, we consider a finite-size system to study the accuracy of the results as a function of the system size (which is practically unrestricted). We show that the finite-size scaling used, e.g. in the variational Monte Carlo method can lead to significant, uncontrolled errors. The presented research is the first step towards applying the DE-GWF method in studies of inhomogeneous situations, including systems with impurities, defects, inhomogeneous phases, or disorder.
Variational study of vacancies in solid 4He with shadow wave functions
NASA Astrophysics Data System (ADS)
Pederiva, F.; Chester, G. V.; Fantoni, S.; Reatto, L.
1997-09-01
We employ the shadow wave function (SWF) formalism to obtain estimates of the energy of formation of a vacancy in hcp, fcc, and bcc 4He crystal at T=0 K. We find that this energy is a strong function of density, in agreement with experiment. The use of a more efficient sampling with a smart Monte Carlo technique, allowed us to observe the motion of the vacancy through the crystal. We also present data on the occupation of the Wigner-Seitz cells. The occupation of the cells changes along the run, showing the mobility of the particles and of the vacancy. As a byproduct of this study we present results for the energy of perfect hcp and bcc crystals described by a SWF.
Gutzwiller wave function for finite systems: superconductivity in the Hubbard model.
Tomski, Andrzej; Kaczmarczyk, Jan
2016-05-01
We study the superconducting phase of the Hubbard model using the Gutzwiller variational wave function (GWF) and the recently proposed diagrammatic expansion technique (DE-GWF). The DE-GWF method works on the level of the full GWF and in the thermodynamic limit. Here, we consider a finite-size system to study the accuracy of the results as a function of the system size (which is practically unrestricted). We show that the finite-size scaling used, e.g. in the variational Monte Carlo method can lead to significant, uncontrolled errors. The presented research is the first step towards applying the DE-GWF method in studies of inhomogeneous situations, including systems with impurities, defects, inhomogeneous phases, or disorder. PMID:27023047
A theoretical model for quantum nanostructures electronic wave functions, magnetic field effects
NASA Astrophysics Data System (ADS)
Even, J.; Cornet, C.; Loualiche, S.
2005-09-01
Analytical solutions of electronic wave functions in symmetric quantum ring (QR), quantum wire (QWR) and quantum dots (QD) structures are given using a parabolic coordinates system. The solutions for low-energy states are combinations of Bessel functions. The density of states of perfect 1D QR and QWR are shown to be equivalent. The continuous evolution from a 0D QD to a perfect 1D QR can be precisely described. The sharp variation of electronic properties, related to the build up of a potential energy barrier at the early stage of the QR formation, is studied analytically. Paramagnetic and diamagnetic couplings to a magnetic field are computed for QR and QD. It is shown theoretically that magnetic field induces an oscillation of the magnetization in QR.
Nowak, Stanislaw; Oldak, Anna; Kluzik, Anna; Drobnik, Leon
2016-01-01
BACKGROUND Controlled induced hypotension guarantees less blood loss and better visibility of the surgical site. The impact of hypotension on post-operative cognitive functions is still being discussed. The objective of this study was to evaluate the effects of controlled induced hypotension on the cognitive functions of patients undergoing functional endoscopic sinus surgery (FESS). MATERIAL AND METHODS We allocated 47 patients with a good grade of preoperative cognitive functions evaluated with the Mini-Mental State Examination to 3 groups (1 - mild hypotension, 2 - intermediate hypotension, 3 - severe hypotension) according to the degree of mean intraoperative arterial pressure compared with preoperative blood pressure. Cognitive functions were evaluated preoperatively, 6 h, and 30 h postoperatively with standardized tests: the Stroop Test, Trail Making Test (TMT), and Verbal Fluency Test (VFT). A decrease in the test results and increase in the number of mistakes made were considered an impairment of cognitive functions. RESULTS A total of 47 patients (group 1 - mild hypotension - 15, group 2 - intermediate hypotension - 19, group 3 - severe hypotension - 13) were included in the study. A significant decrease was observed in all the 3 groups after Stroop A test 6h postoperatively but it improved 30h postoperatively, without differences between the groups. Neither a significant decrease in the test results nor an increase in the number of mistakes was noted for Stroop B tests, TMT A&B tests and VFT. CONCLUSIONS The degree of controlled intraoperative hypotension during FESS did not influence the results of psychometric tests. PMID:26991989
NASA Astrophysics Data System (ADS)
Komninos, Yannis; Mercouris, Theodoros; Nicolaides, Cleanthes A.
2014-01-01
In continuation of our earlier works, we present results concerning the computation of matrix elements of the multipolar Hamiltonian (MPH) between extended wave functions that are obtained numerically. The choice of the MPH is discussed in connection with the broader issue of the form of radiation-atom (or -molecule) interaction that is appropriate for the systematic solution of various problems of matter-radiation interaction. We derive analytic formulas, in terms of the sine-integral function and spherical Bessel functions of various orders, for the cumulative radial integrals that were obtained and calculated by Komninos, Mercouris, and Nicolaides [Phys. Rev. A 71, 023410 (2005), 10.1103/PhysRevA.71.023410]. This development allows the much faster and more accurate computation of such matrix elements, a fact that enhances the efficiency with which the time-dependent Schrödinger equation is solved nonperturbatively, in the framework of the state-specific expansion approach. The formulas are applicable to the general case where a pair of orbitals with angular parts |ℓ1,m1> and |ℓ2,m2> are coupled radiatively. As a test case, we calculate the matrix elements of the electric field and of the paramagnetic operators for on- and off-resonance transitions, between hydrogenic circular states of high angular momentum, whose quantum numbers are chosen so as to satisfy electric dipole and electric quadrupole selection rules. Because of the nature of their wave function (they are nodeless and the large centrifugal barrier keeps their overwhelming part at large distances from the nucleus), the validity of the electric dipole approximation in various applications where the off-resonance couplings must be considered becomes precarious. For example, for the transition from the circular state with n = 20 to that with n = 21, for which
NASA Astrophysics Data System (ADS)
Lesiuk, Michał; Jeziorski, Bogumił; Moszynski, Robert
2013-10-01
In currently most popular explicitly correlated electronic structure theories, the dependence of the wave function on the interelectronic distance rij is built via the correlation factor f (rij). While the short-distance behavior of this factor is well understood, little is known about the form of f (rij) at large rij. In this work, we investigate the optimal form of f (r12) on the example of the helium atom and helium-like ions and several well-motivated models of the wave function. Using the Rayleigh-Ritz variational principle, we derive a differential equation for f (r12) and solve it using numerical propagation or analytic asymptotic expansion techniques. We found that for every model under consideration, f (r12) behaves at large rij as r_{12}^ρ e^{B r_{12}} and obtained simple analytic expressions for the system dependent values of ρ and B. For the ground state of the helium-like ions, the value of B is positive, so that f (r12) diverges as r12 tends to infinity. The numerical propagation confirms this result. When the Hartree-Fock orbitals, multiplied by the correlation factor, are expanded in terms of Slater functions rne-βr, n = 0,…,N, the numerical propagation reveals a minimum in f (r12) with depth increasing with N. For the lowest triplet state, B is negative. Employing our analytical findings, we propose a new "range-separated" form of the correlation factor with the short- and long-range r12 regimes approximated by appropriate asymptotic formulas connected by a switching function. Exemplary calculations show that this new form of f (r12) performs somewhat better than the correlation factors used thus far in the standard R12 or F12 theories.
Franck-Condon factors based on anharmonic vibrational wave functions of polyatomic molecules
NASA Astrophysics Data System (ADS)
Rodriguez-Garcia, Valerie; Yagi, Kiyoshi; Hirao, Kimihiko; Iwata, Suehiro; Hirata, So
2006-07-01
Franck-Condon (FC) integrals of polyatomic molecules are computed on the basis of vibrational self-consistent-field (VSCF) or configuration-interaction (VCI) calculations capable of including vibrational anharmonicity to any desired extent (within certain molecular size limits). The anharmonic vibrational wave functions of the initial and final states are expanded unambiguously by harmonic oscillator basis functions of normal coordinates of the respective electronic states. The anharmonic FC integrals are then obtained as linear combinations of harmonic counterparts, which can, in turn, be evaluated by established techniques taking account of the Duschinsky rotations, geometry displacements, and frequency changes. Alternatively, anharmonic wave functions of both states are expanded by basis functions of just one electronic state, permitting the FC integral to be evaluated directly by the Gauss-Hermite quadrature used in the VSCF and VCI steps [Bowman et al., Mol. Phys. 104, 33 (2006)]. These methods in conjunction with the VCI and coupled-cluster with singles, doubles, and perturbative triples [CCSD(T)] method have predicted the peak positions and intensities of the vibrational manifold in the X˜B12 photoelectron band of H2O with quantitative accuracy. It has revealed that two weakly visible peaks are the result of intensity borrowing from nearby states through anharmonic couplings, an effect explained qualitatively by VSCF and quantitatively by VCI, but not by the harmonic approximation. The X˜B22 photoelectron band of H2CO is less accurately reproduced by this method, likely because of the inability of CCSD(T)/cc-pVTZ to describe the potential energy surface of open-shell H2CO+ with the same high accuracy as in H2O+.