Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C D; Chen, Jing
2016-06-22
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back and scatters off the ion(the signal wave). The interference hologram of the two waves may be used to extract target information embedded in the collision process. Unlike conventional optical holography, however, propagation of the electron wave packet is affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the effect of nonadiabatic ionization is accounted for, and Coulomb potential can be neglected only in the tunnel ionization regime. Our results help paving the way for establishing photoelectron holography for probing spatial and dynamic properties of atoms and molecules.
Nonadiabatic theory of strong-field atomic effects under elliptical polarization
International Nuclear Information System (INIS)
Wang Xu; Eberly, J. H.
2012-01-01
Elliptically polarized laser fields provide a new channel for access to strong-field processes that are either suppressed or not present under linear polarization. Quantum theory is mostly unavailable for their analysis, and we report here results of a systematic study based on a classical ensemble theory with solution of the relevant ab inito time-dependent Newton equations for selected model atoms. The study's approach is necessarily nonadiabatic, as it follows individual electron trajectories leading to single, double, and triple ionizations. Of particular interest are new results bearing on open questions concerning experimental reports of unexplained species dependences as well as double-electron release times that are badly matched by a conventional adiabatic quantum tunneling theory. We also report the first analysis of electron trajectories for sequential and non-sequential triple ionization.
Nonadiabatic effects in electronic and nuclear dynamics
Directory of Open Access Journals (Sweden)
Martin P. Bircher
2017-11-01
Full Text Available Due to their very nature, ultrafast phenomena are often accompanied by the occurrence of nonadiabatic effects. From a theoretical perspective, the treatment of nonadiabatic processes makes it necessary to go beyond the (quasi static picture provided by the time-independent Schrödinger equation within the Born-Oppenheimer approximation and to find ways to tackle instead the full time-dependent electronic and nuclear quantum problem. In this review, we give an overview of different nonadiabatic processes that manifest themselves in electronic and nuclear dynamics ranging from the nonadiabatic phenomena taking place during tunnel ionization of atoms in strong laser fields to the radiationless relaxation through conical intersections and the nonadiabatic coupling of vibrational modes and discuss the computational approaches that have been developed to describe such phenomena. These methods range from the full solution of the combined nuclear-electronic quantum problem to a hierarchy of semiclassical approaches and even purely classical frameworks. The power of these simulation tools is illustrated by representative applications and the direct confrontation with experimental measurements performed in the National Centre of Competence for Molecular Ultrafast Science and Technology.
Nonadiabatic effects in the Quantum Hall regime
International Nuclear Information System (INIS)
Page, D.A.; Brown, E.
1993-01-01
The authors consider the effect of a finite electric field on the states of a Bloch electron in two dimensions, with a uniform magnetic field present. They make use of the concept of electric time translation symmetry and treat the electric and magnetic fields symmetrically in a time dependent formalism. In addition to a wave vector k, the states are characterized by a frequency specifying the behavior under electric time translations. An effective Hamiltonian is employed to obtain the splitting of an isolated Bloch band into open-quotes frequencyclose quotes subbands. The time-averaged velocity and energy of the states are expressed in terms of the frequency dispersion. The relationship to the Stark ladder eigenstates in a scalar potential representation of the electric field is examined. This is seen to justify the use of the averaged energy in determining occupation of the states. In the weak electric field (adiabatic) limit, an expression is recovered for the quantized Hall conductivity of a magnetic subband as a topological invariant. A numerical procedure is outlined and results obtained over a range of electric field strengths. A transition between strong and weak field regimes is seen, with level repulsions between the frequencies playing an important role. The numerical results show how the magnetic subband structure and quantized Hall conductivity emerge as the electric field becomes weaker. In this regime, the behavior can be understood by comparison to the predictions of the adiabatic approximation. The latter predicts crossings in the frequencies at certain locations in wave vector space. Nonadiabatic effects are seen to produce gaps in the frequency spectrum at these locations. 35 refs., 14 figs
Sequential nonadiabatic excitation of large molecules and ions driven by strong laser fields
International Nuclear Information System (INIS)
Markevitch, Alexei N.; Levis, Robert J.; Romanov, Dmitri A.; Smith, Stanley M.; Schlegel, H. Bernhard; Ivanov, Misha Yu.
2004-01-01
Electronic processes leading to dissociative ionization of polyatomic molecules in strong laser fields are investigated experimentally, theoretically, and numerically. Using time-of-flight ion mass spectroscopy, we study the dependence of fragmentation on laser intensity for a series of related molecules and report regular trends in this dependence on the size, symmetry, and electronic structure of a molecule. Based on these data, we develop a model of dissociative ionization of polyatomic molecules in intense laser fields. The model is built on three elements: (i) nonadiabatic population transfer from the ground electronic state to the excited-state manifold via a doorway (charge-transfer) transition; (ii) exponential enhancement of this transition by collective dynamic polarization of all electrons, and (iii) sequential energy deposition in both neutral molecules and resulting molecular ions. The sequential nonadiabatic excitation is accelerated by a counterintuitive increase of a large molecule's polarizability following its ionization. The generic theory of sequential nonadiabatic excitation forms a basis for quantitative description of various nonlinear processes in polyatomic molecules and ions in strong laser fields
Vibrational nonadiabaticity and tunneling effects in transition state theory
International Nuclear Information System (INIS)
Marcus, R.A.
1979-01-01
The usual quantum mechanical derivation of transition state theory is a statistical one (a quasi-equilibrium is assumed) or dynamical. The typical dynamical one defines a set of internal states and assumes vibrational adiabaticity. Effects of nonadiabaticity before and after the transition state are included in the present derivation, assuming a classical treatment of the reaction coordinate. The relation to a dynamical derivation of classical mechanical transition state theory is described, and tunneling effects are considered
Nonadiabatic effect on the quantum heat flux control.
Uchiyama, Chikako
2014-05-01
We provide a general formula of quantum transfer that includes the nonadiabatic effect under periodic environmental modulation by using full counting statistics in Hilbert-Schmidt space. Applying the formula to an anharmonic junction model that interacts with two bosonic environments within the Markovian approximation, we find that the quantum transfer is divided into the adiabatic (dynamical and geometrical phases) and nonadiabatic contributions. This extension shows the dependence of quantum transfer on the initial condition of the anharmonic junction just before the modulation, as well as the characteristic environmental parameters such as interaction strength and cut-off frequency of spectral density. We show that the nonadiabatic contribution represents the reminiscent effect of past modulation including the transition from the initial condition of the anharmonic junction to a steady state determined by the very beginning of the modulation. This enables us to tune the frequency range of modulation, whereby we can obtain the quantum flux corresponding to the geometrical phase by setting the initial condition of the anharmonic junction.
Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect
Bisig, André
2017-01-04
We present a combined theoretical and experimental study, investigating the origin of the enhanced nonadiabaticity of magnetic vortex cores. Scanning transmission x-ray microscopy is used to image the vortex core gyration dynamically to measure the nonadiabaticity with high precision, including a high confidence upper bound. We show theoretically, that the large nonadiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture induced emergent Hall effect. This study demonstrates that the magnetic damping α and nonadiabaticity parameter β are very sensitive to the topology of the magnetic textures, resulting in an enhanced ratio (β/α>1) in magnetic vortex cores or Skyrmions.
Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect
Bisig, André
2017-01-01
We present a combined theoretical and experimental study, investigating the origin of the enhanced nonadiabaticity of magnetic vortex cores. Scanning transmission x-ray microscopy is used to image the vortex core gyration dynamically to measure the nonadiabaticity with high precision, including a high confidence upper bound. We show theoretically, that the large nonadiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture induced emergent Hall effect. This study demonstrates that the magnetic damping α and nonadiabaticity parameter β are very sensitive to the topology of the magnetic textures, resulting in an enhanced ratio (β/α>1) in magnetic vortex cores or Skyrmions.
Nonadiabatic effects in C-Br bond scission in the photodissociation of bromoacetyl chloride
International Nuclear Information System (INIS)
Valero, Rosendo; Truhlar, Donald G.
2006-01-01
Bromoacetyl chloride photodissociation has been interpreted as a paradigmatic example of a process in which nonadiabatic effects play a major role. In molecular beam experiments by Butler and co-workers [J. Chem. Phys. 95, 3848 (1991); J. Chem. Phys. 97, 355 (1992)], BrCH 2 C(O)Cl was prepared in its ground electronic state (S 0 ) and excited with a laser at 248 nm to its first excited singlet state (S 1 ). The two main ensuing photoreactions are the ruptures of the C-Cl bond and of the C-Br bond. A nonadiabatic model was proposed in which the C-Br scission is strongly suppressed due to nonadiabatic recrossing at the barrier formed by the avoided crossing between the S 1 and S 2 states. Recent reduced-dimensional dynamical studies lend support to this model. However, another interpretation that has been given for the experimental results is that the reduced probability of C-Br scission is a consequence of incomplete intramolecular energy redistribution. To provide further insight into this problem, we have studied the energetically lowest six singlet electronic states of bromoacetyl chloride by using an ab initio multiconfigurational perturbative electronic structure method. Stationary points (minima and saddle points) and minimum energy paths have been characterized on the S 0 and S 1 potential energy surfaces. The fourfold way diabatization method has been applied to transform five adiabatic excited electronic states to a diabatic representation. The diabatic potential energy matrix of the first five excited singlet states has been constructed along several cuts of the potential energy hypersurfaces. The thermochemistry of the photodissociation reactions and a comparison with experimental translational energy distributions strongly suggest that nonadiabatic effects dominate the C-Br scission, but that the reaction proceeds along the energetically allowed diabatic pathway to excited-state products instead of being nonadiabatically suppressed. This conclusion is
Memory effects in nonadiabatic molecular dynamics at metal surfaces
DEFF Research Database (Denmark)
Olsen, Thomas; Schiøtz, Jakob
2010-01-01
We study the effect of temporal correlation in a Langevin equation describing nonadiabatic dynamics at metal surfaces. For a harmonic oscillator, the Langevin equation preserves the quantum dynamics exactly and it is demonstrated that memory effects are needed in order to conserve the ground state...... energy of the oscillator. We then compare the result of Langevin dynamics in a harmonic potential with a perturbative master equation approach and show that the Langevin equation gives a better description in the nonperturbative range of high temperatures and large friction. Unlike the master equation......, this approach is readily extended to anharmonic potentials. Using density functional theory, we calculate representative Langevin trajectories for associative desorption of N-2 from Ru(0001) and find that memory effects lower the dissipation of energy. Finally, we propose an ab initio scheme to calculate...
Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport
Kershaw, Vincent F.; Kosov, Daniel S.
2017-12-01
We develop nonequilibrium Green's function-based transport theory, which includes effects of nonadiabatic nuclear motion in the calculation of the electric current in molecular junctions. Our approach is based on the separation of slow and fast time scales in the equations of motion for Green's functions by means of the Wigner representation. Time derivatives with respect to central time serve as a small parameter in the perturbative expansion enabling the computation of nonadiabatic corrections to molecular Green's functions. Consequently, we produce a series of analytic expressions for non-adiabatic electronic Green's functions (up to the second order in the central time derivatives), which depend not solely on the instantaneous molecular geometry but likewise on nuclear velocities and accelerations. An extended formula for electric current is derived which accounts for the non-adiabatic corrections. This theory is concisely illustrated by the calculations on a model molecular junction.
Non-adiabatic effect on Laughlin's argument of the quantum Hall effect
International Nuclear Information System (INIS)
Maruyama, I; Hatsugai, Y
2009-01-01
We have numerically studied a non-adiabatic charge transport in the quantum Hall system pumped by a magnetic flux, as one of the simplest theoretical realizations of non-adiabatic Thouless pumping. In the adiabatic limit, a pumped charge is quantized, known as Laughlin's argument in a cylindrical lattice. In a uniform electric field, we obtained a formula connecting quantized pumping in the adiabatic limit and no-pumping in the sudden limit. The intermediate region between the two limits is determined by the Landau gap. A randomness or impurity effect is also discussed.
Nonadiabatic Ponderomotive Potentials
International Nuclear Information System (INIS)
Dodin IY, Fisch NJ
2005-01-01
An approximate integral of the Manley-Rowe type is found for a particle moving in a high-frequency field, which may interact resonantly with natural particle oscillations. An effective ponderomotive potential is introduced accordingly and can capture nonadiabatic particle dynamics. We show that nonadiabatic ponderomotive barriers can trap classical particles, produce cooling effect, and generate one-way walls for resonant species. Possible atomic applications are also envisioned
Nuclear quantum effects on the nonadiabatic decay mechanism of an excited hydrated electron
Borgis, Daniel; Rossky, Peter J.; Turi, László
2007-11-01
We present a kinetic analysis of the nonadiabatic decay mechanism of an excited state hydrated electron to the ground state. The theoretical treatment is based on a quantized, gap dependent golden rule rate constant formula which describes the nonadiabatic transition rate between two quantum states. The rate formula is expressed in terms of quantum time correlation functions of the energy gap and of the nonadiabatic coupling. These gap dependent quantities are evaluated from three different sets of mixed quantum-classical molecular dynamics simulations of a hydrated electron equilibrated (a) in its ground state, (b) in its first excited state, and (c) on a hypothetical mixed potential energy surface which is the average of the ground and the first excited electronic states. The quantized, gap dependent rate results are applied in a phenomenological kinetic equation which provides the survival probability function of the excited state electron. Although the lifetime of the equilibrated excited state electron is computed to be very short (well under 100fs), the survival probability function for the nonequilibrium process in pump-probe experiments yields an effective excited state lifetime of around 300fs, a value that is consistent with the findings of several experimental groups and previous theoretical estimates.
Nonadiabatic holonomic quantum computation using Rydberg blockade
Kang, Yi-Hao; Chen, Ye-Hong; Shi, Zhi-Cheng; Huang, Bi-Hua; Song, Jie; Xia, Yan
2018-04-01
In this paper, we propose a scheme for realizing nonadiabatic holonomic computation assisted by two atoms and the shortcuts to adiabaticity (STA). The blockade effect induced by strong Rydberg-mediated interaction between two Rydberg atoms provides us the possibility to simplify the dynamics of the system, and the STA helps us design pulses for implementing the holonomic computation with high fidelity. Numerical simulations show the scheme is noise immune and decoherence resistant. Therefore, the current scheme may provide some useful perspectives for realizing nonadiabatic holonomic computation.
Path-integral isomorphic Hamiltonian for including nuclear quantum effects in non-adiabatic dynamics
Tao, Xuecheng; Shushkov, Philip; Miller, Thomas F.
2018-03-01
We describe a path-integral approach for including nuclear quantum effects in non-adiabatic chemical dynamics simulations. For a general physical system with multiple electronic energy levels, a corresponding isomorphic Hamiltonian is introduced such that Boltzmann sampling of the isomorphic Hamiltonian with classical nuclear degrees of freedom yields the exact quantum Boltzmann distribution for the original physical system. In the limit of a single electronic energy level, the isomorphic Hamiltonian reduces to the familiar cases of either ring polymer molecular dynamics (RPMD) or centroid molecular dynamics Hamiltonians, depending on the implementation. An advantage of the isomorphic Hamiltonian is that it can easily be combined with existing mixed quantum-classical dynamics methods, such as surface hopping or Ehrenfest dynamics, to enable the simulation of electronically non-adiabatic processes with nuclear quantum effects. We present numerical applications of the isomorphic Hamiltonian to model two- and three-level systems, with encouraging results that include improvement upon a previously reported combination of RPMD with surface hopping in the deep-tunneling regime.
Coulomb Repulsion Effect in Two-electron Non-adiabatic Tunneling through a One-level redox Molecule
DEFF Research Database (Denmark)
Medvedev, Igor M.; Kuznetsov, Alexander M.; Ulstrup, Jens
2009-01-01
We investigated Coulomb repulsion effects in nonadiabatic (diabatic) two-electron tunneling through a redox molecule with a single electronic level in a symmetric electrochemical contact under ambient conditions, i.e., room temperature and condensed matter environment. The electrochemical contact...
International Nuclear Information System (INIS)
Kroeger, J
2008-01-01
Three aspects of electron-phonon coupling at metal surfaces are reviewed. One aspect is the Kohn effect, which describes an anomalous dispersion relation of surface phonons due to quasi-one-dimensional nesting of Fermi surface contours. The combination of electron energy loss spectroscopy and angle-resolved photoelectron spectroscopy allows us to unambiguously characterize Kohn anomaly systems. A second aspect is the nonadiabatic damping of adsorbate vibrations. Characteristic spectroscopic line shapes of vibrational modes allow us to estimate the amount of energy transfer between the vibrational mode and electron-hole pairs. Case studies of a Kohn anomaly and nonadiabatic damping are provided by the hydrogen- and deuterium-covered Mo(110) surface. As a third aspect of interaction between electrons and phonons, local heating of a C 60 molecule adsorbed on Cu(100) and in contact with the tip of a scanning tunnelling microscope is covered
The effect of nonadiabaticity on the efficiency of quantum memory based on an optical cavity
Veselkova, N. G.; Sokolov, I. V.
2017-07-01
Quantum efficiency is an important characteristic of quantum memory devices that are aimed at recording the quantum state of light signals and its storing and reading. In the case of memory based on an ensemble of cold atoms placed in an optical cavity, the efficiency is restricted, in particular, by relaxation processes in the system of active atomic levels. We show how the effect of the relaxation on the quantum efficiency can be determined in a regime of the memory usage in which the evolution of signals in time is not arbitrarily slow on the scale of the field lifetime in the cavity and when the frequently used approximation of the adiabatic elimination of the quantized cavity mode field cannot be applied. Taking into account the effect of the nonadiabaticity on the memory quality is of interest in view of the fact that, in order to increase the field-medium coupling parameter, a higher cavity quality factor is required, whereas storing and processing of sequences of many signals in the memory implies that their duration is reduced. We consider the applicability of the well-known efficiency estimates via the system cooperativity parameter and estimate a more general form. In connection with the theoretical description of the memory of the given type, we also discuss qualitative differences in the behavior of a random source introduced into the Heisenberg-Langevin equations for atomic variables in the cases of a large and a small number of atoms.
Henriet, Loïc; Sclocchi, Antonio; Orth, Peter P.; Le Hur, Karyn
2017-02-01
We analyze the topological deformations of the ground state manifold of a quantum spin-1/2 in a magnetic field H =H (sinθ cosϕ ,sinθ sinϕ ,cosθ ) induced by a coupling to an ohmic quantum dissipative environment at zero temperature. From Bethe ansatz results and a variational approach, we confirm that the Chern number associated with the geometry of the reduced spin ground state manifold is preserved in the delocalized phase for α <1 . We report a divergence of the Berry curvature at αc=1 for magnetic fields aligned along the equator θ =π /2 . This divergence is caused by the complete quenching of the transverse magnetic field by the bath associated with a gap closing that occurs at the localization Kosterlitz-Thouless quantum phase transition in this model. Recent experiments in quantum circuits have engineered nonequilibrium protocols to access topological properties from a measurement of a dynamical Chern number defined via the out-of-equilibrium spin expectation values. Applying a numerically exact stochastic Schrödinger approach we find that, for a fixed field sweep velocity θ (t )=v t , the bath induces a crossover from (quasi)adiabatic to nonadiabatic dynamical behavior when the spin bath coupling α increases. We also investigate the particular regime H /ωc≪v /H ≪1 with large bath cutoff frequency ωc, where the dynamical Chern number vanishes already at α =1 /2 . In this regime, the mapping to an interacting resonance level model enables us to analytically describe the behavior of the dynamical Chern number in the vicinity of α =1 /2 . We further provide an intuitive physical explanation of the bath-induced breakdown of adiabaticity in analogy to the Faraday effect in electromagnetism. We demonstrate that the driving of the spin leads to the production of a large number of bosonic excitations in the bath, which strongly affect the spin dynamics. Finally, we quantify the spin-bath entanglement and formulate an analogy with an effective
Particle pitch angle diffusion due to nonadiabatic effects in the plasma sheet
International Nuclear Information System (INIS)
Gray, P.C.; Lee, L.C.
1982-01-01
In order to understand certain aspects of the plasma sheet dynamics, a numerical study of the nonadiabatic behavior of particles in a model field geometry is performed. The particle's magnetic moment as a function of time is calculated for various initial parameters, corresponding to various particle energies and degrees of field curvature. It is shown that the magnetic moment changes as the particle passes through the plasma sheet and that the magnitude of the change is related to the curvature of the field at the middle of the plasma sheet. The relation of the magnitude of the change in magnetic moment to the particle's pitch and phase angles as it passes through the sheet is numerically resolved. The nature of the change may be considered as a mechanism for pitch angle diffusion, and the diffusion coefficient is calculated. This scattering mechanism is significant for plasma sheet ions (1--10 keV) as well as energetic electrons (>100 keV)
Nonadiabatic electron response in the Hasegawa-Wakatani equations
International Nuclear Information System (INIS)
Stoltzfus-Dueck, T.; Scott, B. D.; Krommes, J. A.
2013-01-01
Tokamak edge turbulence is strongly influenced by parallel electron physics, which relaxes density and potential fluctuations towards electron adiabatic response. Beginning with the paradigmatic Hasegawa-Wakatani equations (HWEs) for resistive tokamak edge turbulence, a unique decomposition of the electric potential (φ) into adiabatic (a) and nonadiabatic (b) portions is derived, based on the requirement that a neither drive nor respond to the parallel current j ∥ . The form of the decomposition clarifies that, at perpendicular scales large relative to the sound radius, the electron adiabatic response controls the nonzonal φ, not the fluctuating density n. Simple energy balance arguments allow one to rigorously bound the ratio of rms nonzonal nonadiabatic fluctuations (b(tilde sign)) relative to adiabatic ones (ã). The role of the vorticity nonlinearity in transferring energy between adiabatic and nonadiabatic fluctuations aids intuitive understanding of self-sustained turbulence in the HWEs. When the normalized parallel resistivity is weak, b(tilde sign) becomes effectively slaved, allowing the reduction to an approximate one-field model that remains valid for strong turbulence. In addition to guiding physical intuition, the one-field reduction should greatly ease further analytical manipulations. Direct numerical simulation of the 2D HWEs confirms the convergence of the asymptotic formula for b(tilde sign)
Nonadiabatic anharmonic electron transfer
Energy Technology Data Exchange (ETDEWEB)
Schmidt, P. P. [Molecular Physics Research, 6547 Kristina Ursula Court, Falls Church, Virginia 22044 (United States)
2013-03-28
The effect of an inner sphere, local mode vibration on an electron transfer is modeled using the nonadiabatic transition probability (rate) expression together with both the anharmonic Morse and the harmonic oscillator potential. For an anharmonic inner sphere mode, a variational analysis uses harmonic oscillator basis functions to overcome the difficulties evaluating Morse-model Franck-Condon overlap factors. Individual matrix elements are computed with the use of new, fast, robust, and flexible recurrence relations. The analysis therefore readily addresses changes in frequency and/or displacement of oscillator minimums in the different electron transfer states. Direct summation of the individual Boltzmann weighted Franck-Condon contributions avoids the limitations inherent in the use of the familiar high-temperature, Gaussian form of the rate constant. The effect of harmonic versus anharmonic inner sphere modes on the electron transfer is readily seen, especially in the exoergic, inverted region. The behavior of the transition probability can also be displayed as a surface for all temperatures and values of the driving force/exoergicity {Delta}=-{Delta}G. The temperature insensitivity of the transfer rate is clearly seen when the exoergicity equals the collective reorganization energy ({Delta}={Lambda}{sub s}) along a maximum ln (w) vs. {Delta} ridge of the surface. The surface also reveals additional regions for {Delta} where ln (w) appears to be insensitive to temperature, or effectively activationless, for some kinds of inner sphere contributions.
Panholzer, Martin; Gatti, Matteo; Reining, Lucia
2018-04-01
The charge-density response of extended materials is usually dominated by the collective oscillation of electrons, the plasmons. Beyond this feature, however, intriguing many-body effects are observed. They cannot be described by one of the most widely used approaches for the calculation of dielectric functions, which is time-dependent density functional theory (TDDFT) in the adiabatic local density approximation (ALDA). Here, we propose an approximation to the TDDFT exchange-correlation kernel which is nonadiabatic and nonlocal. It is extracted from correlated calculations in the homogeneous electron gas, where we have tabulated it for a wide range of wave vectors and frequencies. A simple mean density approximation allows one to use it in inhomogeneous materials where the density varies on a scale of 1.6 rs or faster. This kernel contains effects that are completely absent in the ALDA; in particular, it correctly describes the double plasmon in the dynamic structure factor of sodium, and it shows the characteristic low-energy peak that appears in systems with low electronic density. It also leads to an overall quantitative improvement of spectra.
Energy Technology Data Exchange (ETDEWEB)
Martínez-Mesa, Aliezer [Departmento de Física Teórica, Universidad de la Habana, San Lázaro y L, La Habana 10400 (Cuba); Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany); Saalfrank, Peter [Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm (Germany)
2015-05-21
Femtosecond-laser pulse driven non-adiabatic spectroscopy and dynamics in molecular and condensed phase systems continue to be a challenge for theoretical modelling. One of the main obstacles is the “curse of dimensionality” encountered in non-adiabatic, exact wavepacket propagation. A possible route towards treating complex molecular systems is via semiclassical surface-hopping schemes, in particular if they account not only for non-adiabatic post-excitation dynamics but also for the initial optical excitation. One such approach, based on initial condition filtering, will be put forward in what follows. As a simple test case which can be compared with exact wavepacket dynamics, we investigate the influence of the different parameters determining the shape of a laser pulse (e.g., its finite width and a possible chirp) on the predissociation dynamics of a NaI molecule, upon photoexcitation of the A(0{sup +}) state. The finite-pulse effects are mapped into the initial conditions for semiclassical surface-hopping simulations. The simulated surface-hopping diabatic populations are in qualitative agreement with the quantum mechanical results, especially concerning the subpicosend photoinduced dynamics, the main deviations being the relative delay of the non-adiabatic transitions in the semiclassical picture. Likewise, these differences in the time-dependent electronic populations calculated via the semiclassical and the quantum methods are found to have a mild influence on the overall probability density distribution. As a result, the branching ratios between the bound and the dissociative reaction channels and the time-evolution of the molecular wavepacket predicted by the semiclassical method agree with those computed using quantum wavepacket propagation. Implications for more challenging molecular systems are given.
Effective lagrangian for strong interactions
International Nuclear Information System (INIS)
Jain, P.
1988-01-01
We attempt to construct a realistic phenomenological Lagrangian in order to describe strong interactions. This is in general a very complicated problem and we shall explore its various aspects. We first include the vector mesons by writing down the most general chiral invariant terms proportional to the Levi-Civita symbol ε μναβ . These terms involve three unknown coefficients, which are calculated by using the experimental results of strong interaction processes. We then calculate the static nucleon properties by finding the solitonic excitations of this model. The results turn out to be, as is also the case for most other vector-pseudoscalar Lagrangians, better than the Skyrme model but are still somewhat different from the experiments. Another aspect that we shall study is the incorporation of scale anomaly of QCD into the Skyrme model. We thus introduce a scalar glueball in our Lagrangian. Here we find an interesting result that the effective glue field dynamically forms a bag for the soliton. Depending on the values of the parameters, we get either a deep bag or a shallow bag. However by including the scalar meson, we find that to get realistic scalar sector we must have the shallow bag. Finally we show some intriguing connections between the chiral quark model, in which the nucleon is described as a solitonic excitation, and the ordinary potential binding quark model
Nonadiabatic transition path sampling
International Nuclear Information System (INIS)
Sherman, M. C.; Corcelli, S. A.
2016-01-01
Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.
Nonadiabatic three-neutrino oscillations in matter
International Nuclear Information System (INIS)
DOlivo, J.C.; Oteo, J.A.
1996-01-01
Oscillations of three neutrinos in matter are analyzed by using the Magnus expansion for the time-evolution operator. We derive a simple expression for the electron-neutrino survival probability which is applied to the examination of the effect of a third neutrino on the nonadiabatic flavor transformations. copyright 1996 The American Physical Society
Volpiani, Pedro S.; Bernardini, Matteo; Larsson, Johan
2017-11-01
The influence of wall thermal conditions on the properties of an impinging shock wave interacting with a turbulent supersonic boundary layer is a research topic that still remains underexplored. In the present study, direct numerical simulations (DNS) are employed to investigate the flow properties of a shock wave interacting with a turbulent boundary layer at free-stream Mach number M∞ = 2.28 with distinct wall thermal conditions and shock strengths. Instantaneous and mean flow fields, wall quantities and the low-frequency unsteadiness are analyzed. While heating contributes to increase the extent of the interaction zone, wall cooling turns out to be a good candidate for flow control. The distribution of the Stanton number shows a good agreement with prior experimental studies and confirms the strong heat transfer and complex pattern within the interaction region. Numerical results indicate that the changes in the interaction length are mainly linked to the incoming boundary layer as suggested in previous studies (Souverein et al., 2013 and Jaunet et al., 2014). This work was supported by the Air Force Office of Scientific Research, Grant FA95501610385.
Modeling non-adiabatic photoexcited reaction dynamics in condensed phases
International Nuclear Information System (INIS)
Coker, D.F.
2003-01-01
Reactions of photoexcited molecules, ions, and radicals in condensed phase environments involve non-adiabatic dynamics over coupled electronic surfaces. We focus on how local environmental symmetries can effect non-adiabatic coupling between excited electronic states and thus influence, in a possibly controllable way, the outcome of photo-excited reactions. Semi-classical and mixed quantum-classical non-adiabatic molecular dynamics methods, together with semi-empirical excited state potentials are used to probe the dynamical mixing of electronic states in different environments from molecular clusters, to simple liquids and solids, and photo-excited reactions in complex reaction environments such as zeolites
Non-adiabatic effects in the electron and phonon spectra of a Peierls insulator
International Nuclear Information System (INIS)
Dzyub, I.P.; Zerov, Yu.E.
1989-08-01
The phonon and electron spectra of the discrete version of the Su, Schrieffer and Heeger model are calculated taking into account the polarization effects. It is shown that there exists a finite probability of electron states relaxation even at zero temperature. (author). 5 refs, 1 fig
Quantum effects in strong fields
International Nuclear Information System (INIS)
Roessler, Lars
2014-01-01
This work is devoted to quantum effects for photons in spatially inhomogeneous fields. Since the purely analytical solution of the corresponding equations is an unsolved problem even today, a main aspect of this work is to use the worldline formalism for scalar QED to develop numerical algorithms for correlation functions beyond perturbative constructions. In a first step we take a look at the 2-Point photon correlation function, in order to understand effects like vacuum polarization or quantum reflection. For a benchmark test of the numerical algorithm we reproduce analytical results in a constant magnetic background. For inhomogeneous fields we calculate for the first time local refractive indices of the quantum vacuum. In this way we find a new de-focusing effect of inhomogeneous magnetic fields. Furthermore the numerical algorithm confirms analytical results for quantum reflection obtained within the local field approximation. In a second step we take a look at higher N-Point functions, with the help of our numerical algorithm. An interesting effect at the level of the 3-Point function is photon splitting. First investigations show that the Adler theorem remains also approximately valid for inhomogeneous fields.
Electron-phonon interactions and intrinsic nonadiabatic state of superconductors
International Nuclear Information System (INIS)
Banacky, Pavol
2007-01-01
Study of band structure of YBa 2 Cu 3 O 7 has shown that electron coupling to A g , B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > E F . Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2 Cu 3 O 6
Electron phonon interactions and intrinsic nonadiabatic state of superconductors
Baňacký, Pavol
2007-09-01
Study of band structure of YBa 2Cu 3O 7 has shown that electron coupling to A g, B 2g and B 3g modes results in fluctuation of saddle point of one of the CuO plane d-pσ band in Y point of 1st BZ across Fermi level. It represents breakdown of adiabatic Born-Oppenheimer approximation and transition of the system into intrinsic nonadiabatic state, ω > EF. Results show that system is stabilized in this state at distorted nuclear geometry. Stabilization effect is mainly due to strong dependence of the electronic motion on instantaneous nuclear momenta. On the lattice scale, the intrinsic nonadiabatic state is geometrically degenerate at broken translation symmetry - system has fluxional nuclear configuration of O2, O3 atoms in CuO planes. It enables formation of mobile bipolarons that can move in the lattice without dissipation. Described effects are absent in non-superconducting YBa 2Cu 3O 6.
Diniz, Leonardo G.; Kirnosov, Nikita; Alijah, Alexander; Mohallem, José R.; Adamowicz, Ludwik
2016-04-01
A very accurate dipole moment curve (DMC) for the ground X1Σ+ electronic state of the 7LiH molecule is reported. It is calculated with the use of all-particle explicitly correlated Gaussian functions with shifted centers. The DMC - the most accurate to our knowledge - and the corresponding highly accurate potential energy curve are used to calculate the transition energies, the transition dipole moments, and the Einstein coefficients for the rovibrational transitions with ΔJ = - 1 and Δv ⩽ 5 . The importance of the non-adiabatic effects in determining these properties is evaluated using the model of a vibrational R-dependent effective reduced mass in the rovibrational calculations introduced earlier (Diniz et al., 2015). The results of the present calculations are used to assess the quality of the two complete linelists of 7LiH available in the literature.
Soudackov, Alexander V; Hammes-Schiffer, Sharon
2015-11-21
Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton
International Nuclear Information System (INIS)
Soudackov, Alexander V.; Hammes-Schiffer, Sharon
2015-01-01
Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton
A design study of non-adiabatic electron guns
International Nuclear Information System (INIS)
Barroso, J.J.; Stellati, C.
1994-01-01
The design of a non-adiabatic gun capable of producing a 10 A, 50 KeV high-quality laminar electron beam is reported. In contrast to the magnetron injection gun with a conical cathode, where the beam is generated initially with a transverse velocity component, in the non-adiabatic gun electrons are extracted in a direction parallel to the axial guide magnetic field. The beam electrons acquire cyclotron motion as result of non-adiabatic processes in a strong non uniform electric field across the modulation anode. Such an extraction method gives rise to favourable features that are explored throughout the work. An extensive numerical simulation study has also been done to minimize velocity and energy spreads. (author). 3 refs, 5 figs, 1 tab
Non-adiabatic perturbations in Ricci dark energy model
International Nuclear Information System (INIS)
Karwan, Khamphee; Thitapura, Thiti
2012-01-01
We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included
Nonadiabatic optical transitions as a turn-on switch for pulse shaping
International Nuclear Information System (INIS)
Hashmi, F. A.; Bouchene, M. A.
2010-01-01
A strong nonresonant, asymmetric ultrashort pulse drives an atomic transition and causes a complete population inversion because of a sudden nonadiabatic jump. This jump is probed in real time by propagating a weak ultrashort pulse in the system which is resonant on an adjacent transition. The probe at the exit of the medium presents an oscillatory structure with the nonadiabatic jump marked in time by the onset of oscillations. The nonadiabatic jump thus acts as a 'turn-on' switch for the shaping of the probe.
Nonadiabatic transitions in electrostatically trapped ammonia molecules
International Nuclear Information System (INIS)
Kirste, Moritz; Schnell, Melanie; Meijer, Gerard; Sartakov, Boris G.
2009-01-01
Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by comparing the trapping times in traps with a zero and a nonzero electric field at the center. Nonadiabatic transitions are seen to dominate the overall loss rate even for the present samples that are at relatively high temperatures of 30 mK. It is anticipated that losses due to nonadiabatic transitions in electric fields are omnipresent in ongoing experiments on cold molecules.
Strong drifts effects on neoclassical transport
International Nuclear Information System (INIS)
Tessarotto, M.; Gregoratto, D.; White, R.B.
1996-01-01
It is well known that strong drifts play an important role in plasma equilibrium, stability and confinement A significant example concerns, in particular for tokamak plasmas, the case of strong toroidal differential rotation produced by E x B drift which is currently regarded as potentially important for its influence in equilibrium, stability and transport. In fact, theoretically, it has been found that shear flow can substantially affect the stability of microinstabilities as well modify substantially transport. Recent experimental observations of enhanced confinement and transport regimes in Tokamaks, show, however, evidence of the existence of strong drifts in the plasma core. These are produced not only by the radial electric field [which gives rise to the E x B drift], but also by density [N s ], temperature [T s ] and mass flow [V = ωRe var-phi , with e var-phi the toroidal unit vector, R the distance for the symmetry axis of the torus and ω being the toroidal angular rotation velocity] profiles which are suitably steep. This implies that, in a significant part of the plasma core, the relevant scale lengths of the gradients [of N s , T s , ω], i.e., respectively L N , L T and L ω can be as large as the radial scale length characterizing the banana orbits, L b . Interestingly enough, the transport estimates obtained appear close or even lower than the predictions based on the simplest neoclassical model. However, as is well known, the latter applies, in a strict sense only in the case of weak drifts and also ignoring even the contribution of shear flow related to strong E x B drift. Thus a fundamental problem appears the extension of neoclassical transport theory to include the effect of strong drifts in Tokamak confinement systems. The goal of this investigation is to develop a general formulation of neoclassical transport embodying such important feature
Non-adiabatic generator-coordinate calculation of H2+
International Nuclear Information System (INIS)
Tostes, J.G.R.; Para Univ., Belem; Toledo Piza, A.F.R. de
1982-10-01
A non-adiabatic calculation of the few lowest J=O states in the H 2+ molecule done within the framework of the Generator Coordinate Method is reported. Substantial accuracy is achivied with the diagonalization of matrices of very modest dimensions. The resulting wavefunctions are strongly dominated by just a few basis states. The computational scheme is set up so as to take the best advantage of good analytical approximations to existing adiabatic molecular wavefunctions. (Author) [pt
Theory of fast (nonadiabatic) nuclear rotation
International Nuclear Information System (INIS)
Nosov, V.G.; Kamchatnov, A.M.
1977-01-01
The theory of backbending is developed taking into accout the increasing role of nonadiabatic effects, which are concerned with quantum number K violation. Above the transition point, rotation quantum number j (>=) jsub(c) (second-kind transition point), all possible values of the quantity K in the interval -J ( Jsub(c) are obtained. The radius of global nucleon mass distribution in the nucleus is defined from the analysis of the experimental moments of inertia in n-phase. It is in agreement with the radius of distribution of protons alone obtained from electron scattering on nuclei. Assuming the simplest singularity of parametric derivative of the Hamiltonian of the system the general theory of non-temperature (ground state)second-kind phase transitions is developed
Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects
Directory of Open Access Journals (Sweden)
A. V. Artemyev
2013-10-01
Full Text Available We investigate dynamics of charged particles in current sheets with the sheared magnetic field. In our previouspaper (Artemyev et al., 2013 we studied the particle motion in such magnetic field configurations on the basis of the quasi-adiabatic theory and conservation of the quasi-adiabatic invariant. In this paper we concentrate on violation of the adiabaticity due to jumps of this invariant and the corresponding effects of stochastization of a particle motion. We compare effects of geometrical and dynamical jumps, which occur due to the presence of the separatrix in the phase plane of charged particle motion. We show that due to the presence of the magnetic field shear, the average value of dynamical jumps is not equal to zero. This effect results in the decrease of the time interval necessary for stochastization of trapped particle motion. We investigate also the effect of the magnetic field shear on transient trajectories, which cross the current sheet boundaries. Presence of the magnetic field shear leads to the asymmetry of reflection and transition of particles in the current sheet. We discuss the possible influence of single-particle effects revealed in this paper on the current sheet structure and dynamics.
Ab initio multiple cloning algorithm for quantum nonadiabatic molecular dynamics
Energy Technology Data Exchange (ETDEWEB)
Makhov, Dmitry V.; Shalashilin, Dmitrii V. [Department of Chemistry, University of Leeds, Leeds LS2 9JT (United Kingdom); Glover, William J.; Martinez, Todd J. [Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)
2014-08-07
We present a new algorithm for ab initio quantum nonadiabatic molecular dynamics that combines the best features of ab initio Multiple Spawning (AIMS) and Multiconfigurational Ehrenfest (MCE) methods. In this new method, ab initio multiple cloning (AIMC), the individual trajectory basis functions (TBFs) follow Ehrenfest equations of motion (as in MCE). However, the basis set is expanded (as in AIMS) when these TBFs become sufficiently mixed, preventing prolonged evolution on an averaged potential energy surface. We refer to the expansion of the basis set as “cloning,” in analogy to the “spawning” procedure in AIMS. This synthesis of AIMS and MCE allows us to leverage the benefits of mean-field evolution during periods of strong nonadiabatic coupling while simultaneously avoiding mean-field artifacts in Ehrenfest dynamics. We explore the use of time-displaced basis sets, “trains,” as a means of expanding the basis set for little cost. We also introduce a new bra-ket averaged Taylor expansion (BAT) to approximate the necessary potential energy and nonadiabatic coupling matrix elements. The BAT approximation avoids the necessity of computing electronic structure information at intermediate points between TBFs, as is usually done in saddle-point approximations used in AIMS. The efficiency of AIMC is demonstrated on the nonradiative decay of the first excited state of ethylene. The AIMC method has been implemented within the AIMS-MOLPRO package, which was extended to include Ehrenfest basis functions.
Strong interaction effects in hadronic atoms
International Nuclear Information System (INIS)
Kaufmann, W.B.
1977-01-01
The WKB method is applied to the calculation of strong interaction-induced level widths and shifts of hadronic atoms. The calculation, while elementary enough for undergraduate quantum mechanics students, gives a good account of kaonic and antiprotonic atom data
Spatial non-adiabatic passage using geometric phases
Energy Technology Data Exchange (ETDEWEB)
Benseny, Albert; Busch, Thomas [Okinawa Institute of Science and Technology Graduate University, Quantum Systems Unit, Okinawa (Japan); Kiely, Anthony; Ruschhaupt, Andreas [University College Cork, Department of Physics, Cork (Ireland); Zhang, Yongping [Okinawa Institute of Science and Technology Graduate University, Quantum Systems Unit, Okinawa (Japan); Shanghai University, Department of Physics, Shanghai (China)
2017-12-15
Quantum technologies based on adiabatic techniques can be highly effective, but often at the cost of being very slow. Here we introduce a set of experimentally realistic, non-adiabatic protocols for spatial state preparation, which yield the same fidelity as their adiabatic counterparts, but on fast timescales. In particular, we consider a charged particle in a system of three tunnel-coupled quantum wells, where the presence of a magnetic field can induce a geometric phase during the tunnelling processes. We show that this leads to the appearance of complex tunnelling amplitudes and allows for the implementation of spatial non-adiabatic passage. We demonstrate the ability of such a system to transport a particle between two different wells and to generate a delocalised superposition between the three traps with high fidelity in short times. (orig.)
Quantum-classical correspondence in steady states of nonadiabatic systems
International Nuclear Information System (INIS)
Fujii, Mikiya; Yamashita, Koichi
2015-01-01
We first present nonadiabatic path integral which is exact formulation of quantum dynamics in nonadiabatic systems. Then, by applying the stationary phase approximations to the nonadiabatic path integral, a semiclassical quantization condition, i.e., quantum-classical correspondence, for steady states of nonadiabatic systems is presented as a nonadiabatic trace formula. The present quantum-classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow degree of freedom, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels
Non-Adiabatic Molecular Dynamics Methods for Materials Discovery
Energy Technology Data Exchange (ETDEWEB)
Furche, Filipp [Univ. of California, Irvine, CA (United States); Parker, Shane M. [Univ. of California, Irvine, CA (United States); Muuronen, Mikko J. [Univ. of California, Irvine, CA (United States); Roy, Saswata [Univ. of California, Irvine, CA (United States)
2017-04-04
The flow of radiative energy in light-driven materials such as photosensitizer dyes or photocatalysts is governed by non-adiabatic transitions between electronic states and cannot be described within the Born-Oppenheimer approximation commonly used in electronic structure theory. The non-adiabatic molecular dynamics (NAMD) methods based on Tully surface hopping and time-dependent density functional theory developed in this project have greatly extended the range of molecular materials that can be tackled by NAMD simulations. New algorithms to compute molecular excited state and response properties efficiently were developed. Fundamental limitations of common non-linear response methods were discovered and characterized. Methods for accurate computations of vibronic spectra of materials such as black absorbers were developed and applied. It was shown that open-shell TDDFT methods capture bond breaking in NAMD simulations, a longstanding challenge for single-reference molecular dynamics simulations. The methods developed in this project were applied to study the photodissociation of acetaldehyde and revealed that non-adiabatic effects are experimentally observable in fragment kinetic energy distributions. Finally, the project enabled the first detailed NAMD simulations of photocatalytic water oxidation by titania nanoclusters, uncovering the mechanism of this fundamentally important reaction for fuel generation and storage.
Strong crystal size effect on deformation twinning
DEFF Research Database (Denmark)
Yu, Qian; Shan, Zhi-Wei; Li, Ju
2010-01-01
plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium’s ideal strength9, 10. We develop a ‘stimulated slip’ model to explain the strong size dependence of deformation twinning......Deformation twinning1, 2, 3, 4, 5, 6 in crystals is a highly coherent inelastic shearing process that controls the mechanical behaviour of many materials, but its origin and spatio-temporal features are shrouded in mystery. Using micro-compression and in situ nano-compression experiments, here we...... find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal7, 8, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation...
Effective Induction Heating around Strongly Magnetized Stars
Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.; Noack, L.; Lüftinger, T.; Zaitsev, V. V.; Lammer, H.
2018-05-01
Planets that are embedded in the changing magnetic fields of their host stars can experience significant induction heating in their interiors caused by the planet’s orbital motion. For induction heating to be substantial, the planetary orbit has to be inclined with respect to the stellar rotation and dipole axes. Using WX UMa, for which the rotation and magnetic axes are aligned, as an example, we show that for close-in planets on inclined orbits, induction heating can be stronger than the tidal heating occurring inside Jupiter’s satellite Io; namely, it can generate a surface heat flux exceeding 2 W m‑2. An internal heating source of such magnitude can lead to extreme volcanic activity on the planet’s surface, possibly also to internal local magma oceans, and to the formation of a plasma torus around the star aligned with the planetary orbit. A strongly volcanically active planet would eject into space mostly SO2, which would then dissociate into oxygen and sulphur atoms. Young planets would also eject CO2. Oxygen would therefore be the major component of the torus. If the O I column density of the torus exceeds ≈1012 cm‑2, the torus could be revealed by detecting absorption signatures at the position of the strong far-ultraviolet O I triplet at about 1304 Å. We estimate that this condition is satisfied if the O I atoms in the torus escape the system at a velocity smaller than 1–10 km s‑1. These estimates are valid also for a tidally heated planet.
Postcollaptical effects in strong Langmuir turbulence
International Nuclear Information System (INIS)
Malkin, V.M.
1989-01-01
The qualitative theory of Langmuir turbulence is constructed, which takes into account the postcollaptical effects. The spectra obtained for Langmuir waves and accelerated electrons differ substantially from those predicted earlier. An interesting feature of new spectra is their dependence on the collapse symmetry. 6 refs
Strong effects in weak nonleptonic decays
International Nuclear Information System (INIS)
Wise, M.B.
1980-04-01
In this report the weak nonleptonic decays of kaons and hyperons are examined with the hope of gaining insight into a recently proposed mechanism for the ΔI = 1/2 rule. The effective Hamiltonian for ΔS = 1 weak nonleptonic decays and that for K 0 -anti K 0 mixing are calculated in the six-quark model using the leading logarithmic approximation. These are used to examine the CP violation parameters of the kaon system. It is found that if Penguin-type diagrams make important contributions to K → ππ decay amplitudes then upcoming experiments may be able to distinguish the six-quark model for CP violation from the superweak model. The weak radiative decays of hyperons are discussed with an emphasis on what they can teach us about hyperon nonleptonic decays and the ΔI = 1/2 rule
Nonadiabatic calculations for tdμ relevant for muon catalyzed fusion
International Nuclear Information System (INIS)
Szalewicz, K.; Jeziorski, B.
1991-01-01
Due to the mass effect, muonic molecular ions are about 200 times smaller than their electronic counterparts. The proximity of the nuclei in the tdμ ion results in fusion taking place within a picosecond. The properties of this ion are central to understanding the phenomenon of muon catalysis. The authors developed a computational method of solving the nonadiabatic Schroedinger equation for the bound and resonance states of tdμ and its isotopic analogues. The method takes into account both the Coulomb interactions and the strong nuclear forces responsible for the fusion reaction. The wave functions obtained from this method were used to predict very accurately branching ratios and transition rates relevant for various stages of the muon catalytic cycle. Knowledge of these quantities will guide the experiments and help to answer the question of feasibility of net energy production via muon catalysis
Disorder effects in strongly correlated uranium compounds
International Nuclear Information System (INIS)
Suellow, S.; Maple, M.B.; Tomuta, D.; Nieuwenhuys, G.J.; Menovsky, A.A.; Mydosh, J.A.; Chau, R.
2001-01-01
Moderate levels of crystallographic disorder can dramatically affect the ground-state properties of heavy fermion compounds. In particular, the role of disorder close to a quantum critical point has been investigated in detail. However, crystallographic disorder is equally effective in altering the properties of magnetically ordered heavy fermion compounds like URh 2 Ge 2 , where disorder-induced spin-glass behavior has been observed. In this system, moreover, the magnetic ground state can be tuned from a spin-glass to a long-range ordered antiferromagnetic one by means of an annealing treatment. The transformation of the magnetic state is accompanied by a transition in the transport properties from 'quasi-insulating' (dρ/dT 2 Ge 2 will be discussed. Of particular interest is the resistivity of as-grown URh 2 Ge 2 , which resembles the Non-Fermi-liquid system UCu 4 Pd, suggesting that a common mechanism - the crystallographic disorder - controls the transport properties of these materials
Classical molecular dynamics simulation of electronically non-adiabatic processes.
Miller, William H; Cotton, Stephen J
2016-12-22
Both classical and quantum mechanics (as well as hybrids thereof, i.e., semiclassical approaches) find widespread use in simulating dynamical processes in molecular systems. For large chemical systems, however, which involve potential energy surfaces (PES) of general/arbitrary form, it is usually the case that only classical molecular dynamics (MD) approaches are feasible, and their use is thus ubiquitous nowadays, at least for chemical processes involving dynamics on a single PES (i.e., within a single Born-Oppenheimer electronic state). This paper reviews recent developments in an approach which extends standard classical MD methods to the treatment of electronically non-adiabatic processes, i.e., those that involve transitions between different electronic states. The approach treats nuclear and electronic degrees of freedom (DOF) equivalently (i.e., by classical mechanics, thereby retaining the simplicity of standard MD), and provides "quantization" of the electronic states through a symmetrical quasi-classical (SQC) windowing model. The approach is seen to be capable of treating extreme regimes of strong and weak coupling between the electronic states, as well as accurately describing coherence effects in the electronic DOF (including the de-coherence of such effects caused by coupling to the nuclear DOF). A survey of recent applications is presented to illustrate the performance of the approach. Also described is a newly developed variation on the original SQC model (found universally superior to the original) and a general extension of the SQC model to obtain the full electronic density matrix (at no additional cost/complexity).
Non-adiabatic perturbations in multi-component perfect fluids
Energy Technology Data Exchange (ETDEWEB)
Koshelev, N.A., E-mail: koshna71@inbox.ru [Ulyanovsk State University, Leo Tolstoy str 42, 432970 (Russian Federation)
2011-04-01
The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.
Non-adiabatic perturbations in multi-component perfect fluids
International Nuclear Information System (INIS)
Koshelev, N.A.
2011-01-01
The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models
Nonadiabatic electron wavepacket dynamics behind molecular autoionization
Matsuoka, Takahide; Takatsuka, Kazuo
2018-01-01
A theoretical method for real-time dynamics of nonadiabatic reorganization of electronic configurations in molecules is developed, with dual aim that the intramolecular electron dynamics can be probed by means of direct and/or indirect photoionizations and that the physical origins behind photoionization signals attained in the time domain can be identified in terms of the language of time-dependent quantum chemistry. In doing so, we first formulate and implement a new computational scheme for nonadiabatic electron dynamics associated with molecular ionization, which well fits in the general theory of nonadiabatic electron dynamics. In this method, the total nonadiabatic electron wavepackets are propagated in time directly with complex natural orbitals without referring to Hartree-Fock molecular orbitals, and the amount of electron flux from a molecular region leading to ionization is evaluated in terms of the relevant complex natural orbitals. In the second half of this paper, we apply the method to electron dynamics in the elementary processes consisting of the Auger decay to demonstrate the methodological significance. An illustrative example is taken from an Auger decay starting from the 2a1 orbital hole-state of H2O+. The roles of nuclear momentum (kinetic) couplings in electronic-state mixing during the decay process are analyzed in terms of complex natural orbitals, which are schematically represented in the conventional language of molecular symmetry of the Hartree-Fock orbitals.
Nonadiabatic particle motion in magnetic mirror traps
International Nuclear Information System (INIS)
Irie, H.; Otsuka, S.; Varma, R.K.; Watanabe, T.; Nishikawa, Kyoji.
1982-01-01
By numerical integration of the equation of single particle motion, the basic features of the actual nonadiabatic escape of particles are studied. The results are compared with the predictions of two existing theoretical models: ''diffusion'' model derived by B. V. Chirikov and ''tunneling'' model introduced by R. K. Varma. (author)
Nonlinear charge reduction effect in strongly coupled plasmas
International Nuclear Information System (INIS)
Sarmah, D; Tessarotto, M; Salimullah, M
2006-01-01
The charge reduction effect, produced by the nonlinear Debye screening of high-Z charges occurring in strongly coupled plasmas, is investigated. An analytic asymptotic expression is obtained for the charge reduction factor (f c ) which determines the Debye-Hueckel potential generated by a charged test particle. Its relevant parametric dependencies are analysed and shown to predict a strong charge reduction effect in strongly coupled plasmas
Quantum chaos induced by nonadiabatic coupling in wave-packet dynamics
International Nuclear Information System (INIS)
Higuchi, Hisashi; Takatsuka, Kazuo
2002-01-01
The effect of nonadiabatic coupling due to breakdown of the Born-Oppenheimer approximation on chaos is investigated. A couple of measures (indicators) that detect the extent of chaos in wave-packet dynamics on coupled potential functions are devised. Using them, we show that chaos is indeed induced by a nonadiabatic coupling in individual time-dependent wave-packet dynamics. This chaos is genuinely of quantum nature, since it arises from bifurcation and merging of a wave packet at the quasicrossing region of two coupled potential functions
Peters, William K.; Tiwari, Vivek; Jonas, David M.
2017-11-01
The nonadiabatic states and dynamics are investigated for a linear vibronic coupling Hamiltonian with a static electronic splitting and weak off-diagonal Jahn-Teller coupling through a single vibration with a vibrational-electronic resonance. With a transformation of the electronic basis, this Hamiltonian is also applicable to the anti-correlated vibration in a symmetric homodimer with marginally strong constant off-diagonal coupling, where the non-adiabatic states and dynamics model electronic excitation energy transfer or self-exchange electron transfer. For parameters modeling a free-base naphthalocyanine, the nonadiabatic couplings are deeply quantum mechanical and depend on wavepacket width; scalar couplings are as important as the derivative couplings that are usually interpreted to depend on vibrational velocity in semiclassical curve crossing or surface hopping theories. A colored visualization scheme that fully characterizes the non-adiabatic states using the exact factorization is developed. The nonadiabatic states in this nested funnel have nodeless vibrational factors with strongly avoided zeroes in their vibrational probability densities. Vibronic dynamics are visualized through the vibrational coordinate dependent density of the time-dependent dipole moment in free induction decay. Vibrational motion is amplified by the nonadiabatic couplings, with asymmetric and anisotropic motions that depend upon the excitation polarization in the molecular frame and can be reversed by a change in polarization. This generates a vibrational quantum beat anisotropy in excess of 2/5. The amplitude of vibrational motion can be larger than that on the uncoupled potentials, and the electronic population transfer is maximized within one vibrational period. Most of these dynamics are missed by the adiabatic approximation, and some electronic and vibrational motions are completely suppressed by the Condon approximation of a coordinate-independent transition dipole between
OBSERVATION OF STRONG - STRONG AND OTHER BEAM - BEAM EFFECTS IN RHIC
International Nuclear Information System (INIS)
FISCHER, W.; BLASKIEWICZ, M.; BRENNAN, J.M.; CAMERON, P.; CONNOLLY, R.; MONTAG, C.; PEGGS, S.; PILAT, F.; PTITSYN, V.; TEPIKIAN, S.; TRBOJEVIC, D.; VAN ZEIJTS, J.
2003-01-01
RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. For the first time, coherent beam-beam modes were observed in a bunched beam hadron collider. Other beam-beam effects in RHIC were observed in operation and in dedicated experiments with gold ions, deuterons and protons. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. During ramps unequal radio frequencies in the two rings cause the crossing points to move longitudinally. Thus bunches experience beam-beam interactions only in intervals and the tunes are modulated. In this article we summarize the most important beam-beam observations made so far
Semiclassical quantization of nonadiabatic systems with hopping periodic orbits
International Nuclear Information System (INIS)
Fujii, Mikiya; Yamashita, Koichi
2015-01-01
We present a semiclassical quantization condition, i.e., quantum–classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller’s trace formula to a nonadiabatic form. The quantum–classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics
Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons
International Nuclear Information System (INIS)
Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; Andre, M.; Owen, C. J.
2011-01-01
We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.
Nonadiabatic quantum state control of many bosons in few wells
DEFF Research Database (Denmark)
Tichy, Malte C.; Kock Pedersen, Mads; Mølmer, Klaus
2013-01-01
We present a fast scheme for arbitrary unitary control of interacting bosonic atoms in a double well. Assuming fixed interwell tunneling rate and intrawell interaction strength, we control the many-atom state by a discrete sequence of shifts of the single-well energies. For strong interactions......, resonant tunneling transitions implement beam-splitter U(2) rotations among atom number eigenstates, which can be combined and, thus, permit full controllability. By numerically optimizing such sequences of couplings at avoided level crossings, we extend the realm of full controllability to a wide range...... of realistic interaction parameters, while we remain in the simple control space. We demonstrate the efficiency and the high achievable fidelity of our proposal with nonadiabatic population transfer, NOON-state creation, a cnot gate, and a transistorlike, conditional evolution of several atoms....
Strong correlation effects on surfaces of topological insulators via holography
Seo, Yunseok; Song, Geunho; Sin, Sang-Jin
2017-07-01
We investigate the effects of strong correlation on the surface state of a topological insulator (TI). We argue that electrons in the regime of crossover from weak antilocalization to weak localization are strongly correlated, and calculate the magnetotransport coefficients of TIs using the gauge-gravity principle. Then, we examine the magnetoconductivity (MC) formula and find excellent agreement with the data of chrome-doped Bi2Te3 in the crossover regime. We also find that the cusplike peak in MC at low doping is absent, which is natural since quasiparticles disappear due to the strong correlation.
International Nuclear Information System (INIS)
Kanno, Manabu; Kono, Hirohiko; Fujimura, Yuichi; Lin, Sheng H.
2010-01-01
We theoretically investigated the nonadiabatic couplings between optically induced π-electron rotations and molecular vibrations in a chiral aromatic molecule irradiated by a nonhelical, linearly polarized laser pulse. The results of wave packet dynamics simulation show that the vibrational amplitudes strongly depend on the initial rotation direction, clockwise or counterclockwise, which is controlled by the polarization direction of the incident pulse. This suggests that attosecond π-electron rotations can be observed by spectroscopic detection of femtosecond molecular vibrations.
Energy Technology Data Exchange (ETDEWEB)
Zareh, Masoud; Heidari, Mohammad Ghorbani [Islamic Azad University, Tehran (Iran, Islamic Republic of)
2016-07-15
This research represents an experimental investigation of the metastable flow and re-condensation phenomenon through non-adiabatic lateral helical capillary tubes and suction tube heat exchanger. The results show that mass flux ratio has a vital role: It affects metastable flow and also reverse heat transfer phenomenon through non-adiabatic helical capillary tube. Therefore, by increasing of the mass flux ratio, the rate of heat transfer between them decreases. In contrast to the strong rate condition of heat transfer between them, reverse heat transfer or re-condensation maybe happen. Moreover, experimental results show that for R134 flow with mass flux ratio more than 57.84, metastable flow exists in non-adiabatic capillary tube with 0.9144 mm inner diameter, 30 mm coil diameter, 6.18 m length, 4 mm inner diameter of compressor suction tube.
Strong expectations cancel locality effects: evidence from Hindi.
Directory of Open Access Journals (Sweden)
Samar Husain
Full Text Available Expectation-driven facilitation (Hale, 2001; Levy, 2008 and locality-driven retrieval difficulty (Gibson, 1998, 2000; Lewis & Vasishth, 2005 are widely recognized to be two critical factors in incremental sentence processing; there is accumulating evidence that both can influence processing difficulty. However, it is unclear whether and how expectations and memory interact. We first confirm a key prediction of the expectation account: a Hindi self-paced reading study shows that when an expectation for an upcoming part of speech is dashed, building a rarer structure consumes more processing time than building a less rare structure. This is a strong validation of the expectation-based account. In a second study, we show that when expectation is strong, i.e., when a particular verb is predicted, strong facilitation effects are seen when the appearance of the verb is delayed; however, when expectation is weak, i.e., when only the part of speech "verb" is predicted but a particular verb is not predicted, the facilitation disappears and a tendency towards a locality effect is seen. The interaction seen between expectation strength and distance shows that strong expectations cancel locality effects, and that weak expectations allow locality effects to emerge.
Strong expectations cancel locality effects: evidence from Hindi.
Husain, Samar; Vasishth, Shravan; Srinivasan, Narayanan
2014-01-01
Expectation-driven facilitation (Hale, 2001; Levy, 2008) and locality-driven retrieval difficulty (Gibson, 1998, 2000; Lewis & Vasishth, 2005) are widely recognized to be two critical factors in incremental sentence processing; there is accumulating evidence that both can influence processing difficulty. However, it is unclear whether and how expectations and memory interact. We first confirm a key prediction of the expectation account: a Hindi self-paced reading study shows that when an expectation for an upcoming part of speech is dashed, building a rarer structure consumes more processing time than building a less rare structure. This is a strong validation of the expectation-based account. In a second study, we show that when expectation is strong, i.e., when a particular verb is predicted, strong facilitation effects are seen when the appearance of the verb is delayed; however, when expectation is weak, i.e., when only the part of speech "verb" is predicted but a particular verb is not predicted, the facilitation disappears and a tendency towards a locality effect is seen. The interaction seen between expectation strength and distance shows that strong expectations cancel locality effects, and that weak expectations allow locality effects to emerge.
Du, Likai; Lan, Zhenggang
2015-04-14
Nonadiabatic dynamics simulations have rapidly become an indispensable tool for understanding ultrafast photochemical processes in complex systems. Here, we present our recently developed on-the-fly nonadiabatic dynamics package, JADE, which allows researchers to perform nonadiabatic excited-state dynamics simulations of polyatomic systems at an all-atomic level. The nonadiabatic dynamics is based on Tully's surface-hopping approach. Currently, several electronic structure methods (CIS, TDHF, TDDFT(RPA/TDA), and ADC(2)) are supported, especially TDDFT, aiming at performing nonadiabatic dynamics on medium- to large-sized molecules. The JADE package has been interfaced with several quantum chemistry codes, including Turbomole, Gaussian, and Gamess (US). To consider environmental effects, the Langevin dynamics was introduced as an easy-to-use scheme into the standard surface-hopping dynamics. The JADE package is mainly written in Fortran for greater numerical performance and Python for flexible interface construction, with the intent of providing open-source, easy-to-use, well-modularized, and intuitive software in the field of simulations of photochemical and photophysical processes. To illustrate the possible applications of the JADE package, we present a few applications of excited-state dynamics for various polyatomic systems, such as the methaniminium cation, fullerene (C20), p-dimethylaminobenzonitrile (DMABN) and its primary amino derivative aminobenzonitrile (ABN), and 10-hydroxybenzo[h]quinoline (10-HBQ).
Strong-coupling polaron effect in quantum dots
International Nuclear Information System (INIS)
Zhu Kadi; Gu Shiwei
1993-11-01
Strong-coupling polaron in a parabolic quantum dot is investigated by the Landau-Pekar variational treatment. The polaron binding energy and the average number of virtual phonons around the electron as a function of the effective confinement length of the quantum dot are obtained in Gaussian function approximation. It is shown that both the polaron binding energy and the average number of virtual phonons around the electron decrease by increasing the effective confinement length. The results indicate that the polaronic effects are more pronounced in quantum dots than those in two-dimensional and three-dimensional cases. (author). 15 refs, 4 figs
Glover, William J; Mori, Toshifumi; Schuurman, Michael S; Boguslavskiy, Andrey E; Schalk, Oliver; Stolow, Albert; Martínez, Todd J
2018-04-28
The excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene (BD), has long been the subject of controversy due to its strong coupling, ultrafast time scales and the difficulties that theory faces in describing the relevant electronic states in a balanced fashion. Here we apply Ab Initio Multiple Spawning (AIMS) using state-averaged complete active space multistate second order perturbation theory [SA-3-CAS(4/4)-MSPT2] which describes both static and dynamic electron correlation effects, providing a balanced description of both the initially prepared bright 1 1 B u (ππ*) state and non-adiabatically coupled dark 2 1 A g state of BD. Importantly, AIMS allows for on-the-fly calculations of experimental observables. We validate our approach by directly simulating the time resolved photoelectron-photoion coincidence spectroscopy results presented in Paper I [A. E. Boguslavskiy et al., J. Chem. Phys. 148, 164302 (2018)], demonstrating excellent agreement with experiment. Our simulations reveal that the initial excitation to the 1 1 B u state rapidly evolves via wavepacket dynamics that follow both bright- and dark-state pathways as well as mixtures of these. In order to test the sensitivity of the AIMS results to the relative ordering of states, we considered two hypothetical scenarios biased toward either the bright 1 B u or the dark 2 1 A g state. In contrast with AIMS/SA-3-CAS(4/4)-MSPT2 simulations, neither of these scenarios yields favorable agreement with experiment. Thus, we conclude that the excited state non-adiabatic dynamics in BD involves both of these ultrafast pathways.
Golibrzuch, Kai; Shirhatti, Pranav R; Altschäffel, Jan; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M; Bartels, Christof
2013-09-12
Translational motion is believed to be a spectator degree of freedom in electronically nonadiabatic vibrational energy transfer between molecules and metal surfaces, but the experimental evidence available to support this view is limited. In this work, we have experimentally determined the translational inelasticity in collisions of NO molecules with a single-crystal Au(111) surface-a system with strong electronic nonadiabaticity. State-to-state molecular beam surface scattering was combined with an IR-UV double resonance scheme to obtain high-resolution time-of-flight data. The measurements include vibrationally elastic collisions (v = 3→3, 2→2) as well as collisions where one or two quanta of molecular vibration are excited (2→3, 2→4) or de-excited (2→1, 3→2, 3→1). In addition, we have carried out comprehensive measurements of the effects of rotational excitation on the translational energy of the scattered molecules. We find that under all conditions of this work, the NO molecules lose a large fraction (∼0.45) of their incidence translational energy to the surface. Those molecules that undergo vibrational excitation (relaxation) during the collision recoil slightly slower (faster) than vibrationally elastically scattered molecules. The amount of translational energy change depends on the surface temperature. The translation-to-rotation coupling, which is well-known for v = 0→0 collisions, is found to be significantly weaker for vibrationally inelastic than elastic channels. Our results clearly show that the spectator view of the translational motion in electronically nonadiabatic vibrational energy transfer between NO and Au(111) is only approximately correct.
Glover, William J.; Mori, Toshifumi; Schuurman, Michael S.; Boguslavskiy, Andrey E.; Schalk, Oliver; Stolow, Albert; Martínez, Todd J.
2018-04-01
The excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene (BD), has long been the subject of controversy due to its strong coupling, ultrafast time scales and the difficulties that theory faces in describing the relevant electronic states in a balanced fashion. Here we apply Ab Initio Multiple Spawning (AIMS) using state-averaged complete active space multistate second order perturbation theory [SA-3-CAS(4/4)-MSPT2] which describes both static and dynamic electron correlation effects, providing a balanced description of both the initially prepared bright 11Bu (ππ*) state and non-adiabatically coupled dark 21Ag state of BD. Importantly, AIMS allows for on-the-fly calculations of experimental observables. We validate our approach by directly simulating the time resolved photoelectron-photoion coincidence spectroscopy results presented in Paper I [A. E. Boguslavskiy et al., J. Chem. Phys. 148, 164302 (2018)], demonstrating excellent agreement with experiment. Our simulations reveal that the initial excitation to the 11Bu state rapidly evolves via wavepacket dynamics that follow both bright- and dark-state pathways as well as mixtures of these. In order to test the sensitivity of the AIMS results to the relative ordering of states, we considered two hypothetical scenarios biased toward either the bright 1Bu or the dark 21Ag state. In contrast with AIMS/SA-3-CAS(4/4)-MSPT2 simulations, neither of these scenarios yields favorable agreement with experiment. Thus, we conclude that the excited state non-adiabatic dynamics in BD involves both of these ultrafast pathways.
New results on strong-interaction effects in antiprotonic hydrogen
Gotta, D; Augsburger, M A; Borchert, G L; Castelli, C M; Chatellard, D; El-Khoury, P; Egger, J P; Gorke, H; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Nelms, N; Rashid, K; Schult, O W B; Siems, T; Simons, L M
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the low-energy antiproton ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using charge-coupled devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (33 refs).
New results on strong-interaction effects in antiprotonic hydrogen
International Nuclear Information System (INIS)
Anagnostopoulos, D. F.; Augsburger, M.; Borchert, G.; Castelli, C.; Chatellard, D.; El-Khoury, P.; Egger, J.-P.; Gorke, H.; Gotta, D.; Hauser, P.; Indelicato, P.; Kirch, K.; Lenz, S.; Nelms, N.; Rashid, K.; Schult, O. W. B.; Siems, Th.; Simons, L. M.
1999-01-01
Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the Low-Energy Antiproton Ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using Charge-Coupled Devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction
Strong Gravity Effects of Rotating Black Holes: Quasiperiodic Oscillations
Aliev, Alikram N.; Esmer, Göksel Daylan; Talazan, Pamir
2012-01-01
We explore strong gravity effects of the geodesic motion in the spacetime of rotating black holes in general relativity and braneworld gravity. We focus on the description of the motion in terms of three fundamental frequencies: The orbital frequency, the radial and vertical epicyclic frequencies. For a Kerr black hole, we perform a detailed numerical analysis of these frequencies at the innermost stable circular orbits and beyond them as well as at the characteristic stable orbits, at which ...
Humeniuk, Alexander; Mitrić, Roland
2017-12-01
A software package, called DFTBaby, is published, which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton's equations of motion for the nuclei together with the electronic Schrödinger equation. Non-adiabatic effects are included by surface hopping. As an example, the program is applied to the optimization of excited states and non-adiabatic dynamics of polyfluorene. The python and Fortran source code is available at http://www.dftbaby.chemie.uni-wuerzburg.de.
Two-level system in spin baths: Non-adiabatic dynamics and heat transport
Segal, Dvira
2014-04-01
We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, corresponding to the harmonic bath with an effective, temperature-dependent, spectral density function. We then proceed and study the heat current characteristics in the out-of-equilibrium spin-spin-bath model, with a two-state subsystem bridging two thermal spin-baths of different temperatures. We compare the behavior of this model to the case of a spin connecting boson baths, and demonstrate pronounced qualitative differences between the two models. Specifically, we focus on the development of the thermal diode effect, and show that the spin-spin-bath model cannot support it at weak (subsystem-bath) coupling, while in the intermediate-strong coupling regime its rectifying performance outplays the spin-boson model.
Two-level system in spin baths: Non-adiabatic dynamics and heat transport
Energy Technology Data Exchange (ETDEWEB)
Segal, Dvira [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, 80 Saint George St., Toronto, Ontario M5S 3H6 (Canada)
2014-04-28
We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, corresponding to the harmonic bath with an effective, temperature-dependent, spectral density function. We then proceed and study the heat current characteristics in the out-of-equilibrium spin-spin-bath model, with a two-state subsystem bridging two thermal spin-baths of different temperatures. We compare the behavior of this model to the case of a spin connecting boson baths, and demonstrate pronounced qualitative differences between the two models. Specifically, we focus on the development of the thermal diode effect, and show that the spin-spin-bath model cannot support it at weak (subsystem-bath) coupling, while in the intermediate-strong coupling regime its rectifying performance outplays the spin-boson model.
The nonadiabatic deactivation paths of pyrrole
International Nuclear Information System (INIS)
Barbatti, Mario; Vazdar, Mario; Aquino, Adelia J. A.; Eckert-Maksic, Mirjana; Lischka, Hans
2006-01-01
Multireference configuration interaction (MRCI) calculations have been performed for pyrrole with the aim of providing an explanation for the experimentally observed photochemical deactivation processes. Potential energy curves and minima on the crossing seam were determined using the analytic MRCI gradient and nonadiabatic coupling features of the COLUMBUS program system. A new deactivation mechanism based on an out-of-plane ring deformation is presented. This mechanism directly couples the charge transfer 1 ππ* and ground states. It may be responsible for more than 50% of the observed photofragments of ππ*-excited pyrrole. The ring deformation mechanism should act complementary to the previously proposed NH-stretching mechanism, thus offering a more complete interpretation of the pyrrole photodynamics
Strong gravity effects in accreting black-hole systems
International Nuclear Information System (INIS)
Niedzwiecki, A.
2006-01-01
I briefly review current status of studying effects of strong gravity in X-ray astronomy. Matter accreting onto a black hole probes the relativistic region of space-time and the high-energy radiation it produces should contain signatures of strong gravity effects. Current X-ray observations provide the evidence that the observed emission originates, in some cases, at a distance of a few gravitational radii from a black hole. Moreover, certain observations invoke interpretations favouring rapid rotation of the black hole. Some observational properties of black hole systems are supposed to result from the lack of a material surface in these objects. I consider further effects, specific for the black hole environment, which can be studied in X-ray data. Bulk motion Comptonization, which would directly reveal converging flow of matter plunging into a black hole, is unlikely to be important in formation of X-ray spectra. Similarly, Penrose processes are unlikely to give observational effects, although this issue has not been thoroughly studied so far for all plausible radiative mechanisms. (author)
STRONG FIELD EFFECTS ON PULSAR ARRIVAL TIMES: GENERAL ORIENTATIONS
International Nuclear Information System (INIS)
Wang Yan; Creighton, Teviet; Price, Richard H.; Jenet, Frederick A.
2009-01-01
A pulsar beam passing close to a black hole can provide a probe of very strong gravitational fields even if the pulsar itself is not in a strong field region. In the case that the spin of the hole can be ignored, we have previously shown that all strong field effects on the beam can be understood in terms of two 'universal' functions: F(φ in ) and T(φ in ) of the angle of beam emission φ in ; these functions are universal in that they depend only on a single parameter, the pulsar/black hole distance from which the beam is emitted. Here we apply this formalism to general pulsar-hole-observer geometries, with arbitrary alignment of the pulsar spin axis and arbitrary pulsar beam direction and angular width. We show that the analysis of the observational problem has two distinct elements: (1) the computation of the location and trajectory of an observer-dependent 'keyhole' direction of emission in which a signal can be received by the observer; and (2) the determination of an annulus that represents the set of directions containing beam energy. Examples of each are given along with an example of a specific observational scenario.
Effective interactions in strongly-coupled quantum systems
International Nuclear Information System (INIS)
Chen, J.M.C.
1986-01-01
In this thesis, they study the role of effective interactions in strongly-coupled Fermi systems where the short-range correlations introduce difficulties requiring special treatment. The correlated basis function method provides the means to incorporate the short-range correlations and generate the matrix elements of the Hamiltonian and identity operators in a nonorthogonal basis of states which are so important to their studies. In the first half of the thesis, the particle-hole channel is examined to elucidate the effects of collective excitations. Proceeding from a least-action principle, a generalization of the random-phase approximation is developed capable of describing such strongly-interacting Fermi systems as nuclei, nuclear matter, neutron-star matter, and liquid 3 He. A linear response of dynamically correlated system to a weak external perturbation is also derived based on the same framework. In the second half of the thesis, the particle-particle channel is examined to elucidate the effects of pairing in nuclear and neutron-star matter
Strong correlation effects in theoretical STM studies of magnetic adatoms
Dang, Hung T.; dos Santos Dias, Manuel; Liebsch, Ansgar; Lounis, Samir
2016-03-01
We present a theoretical study for the scanning tunneling microscopy (STM) spectra of surface-supported magnetic nanostructures, incorporating strong correlation effects. As concrete examples, we study Co and Mn adatoms on the Cu(111) surface, which are expected to represent the opposite limits of Kondo physics and local moment behavior, using a combination of density functional theory and both quantum Monte Carlo and exact diagonalization impurity solvers. We examine in detail the effects of temperature T , correlation strength U , and impurity d electron occupancy Nd on the local density of states. We also study the effective coherence energy scale, i.e., the Kondo temperature TK, which can be extracted from the STM spectra. Theoretical STM spectra are computed as a function of STM tip position relative to each adatom. Because of the multiorbital nature of the adatoms, the STM spectra are shown to consist of a complicated superposition of orbital contributions, with different orbital symmetries, self-energies, and Kondo temperatures. For a Mn adatom, which is close to half-filling, the STM spectra are featureless near the Fermi level. On the other hand, the quasiparticle peak for a Co adatom gives rise to strongly position-dependent Fano line shapes.
Salna, Bridget; Benabbas, Abdelkrim; Russo, Douglas; Champion, Paul M
2017-07-20
A proper description of proton donor-acceptor (D-A) distance fluctuations is crucial for understanding tunneling in proton-coupled electron transport (PCET). The typical harmonic approximation for the D-A potential results in a Gaussian probability distribution, which does not appropriately reflect the electronic repulsion forces that increase the energetic cost of sampling shorter D-A distances. Because these shorter distances are the primary channel for thermally activated tunneling, the analysis of tunneling kinetics depends sensitively on the inherently anharmonic nature of the D-A interaction. Thus, we have used quantum chemical calculations to account for the D-A interaction and developed an improved model for the analysis of experimental tunneling kinetics. Strong internal electric fields are also considered and found to contribute significantly to the compressive forces when the D-A distance distribution is positioned below the van der Waals contact distance. This model is applied to recent experiments on the wild type (WT) and a double mutant (DM) of soybean lipoxygenase-1 (SLO). The compressive force necessary to prepare the tunneling-active distribution in WT SLO is found to fall in the ∼ nN range, which greatly exceeds the measured values of molecular motor and protein unfolding forces. This indicates that ∼60-100 MV/cm electric fields, aligned along the D-A bond axis, must be generated by an enzyme conformational interconversion that facilitates the PCET tunneling reaction. Based on the absolute value of the measured tunneling rate, and using previously calculated values of the electronic matrix element, the population of this tunneling-active conformation is found to lie in the range 10 -5 -10 -7 , indicating this is a rare structural fluctuation that falls well below the detection threshold of recent ENDOR experiments. Additional analysis of the DM tunneling kinetics leads to a proposal that a disordered (high entropy) conformation could be
Strong effects of ionizing radiation from Chernobyl on mutation rates.
Møller, Anders Pape; Mousseau, Timothy A
2015-02-10
In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.
Zhu, Chaoyuan; Lin, Sheng Hsien
2006-07-28
Unified semiclasical solution for general nonadiabatic tunneling between two adiabatic potential energy surfaces is established by employing unified semiclassical solution for pure nonadiabatic transition [C. Zhu, J. Chem. Phys. 105, 4159 (1996)] with the certain symmetry transformation. This symmetry comes from a detailed analysis of the reduced scattering matrix for Landau-Zener type of crossing as a special case of nonadiabatic transition and nonadiabatic tunneling. Traditional classification of crossing and noncrossing types of nonadiabatic transition can be quantitatively defined by the rotation angle of adiabatic-to-diabatic transformation, and this rotational angle enters the analytical solution for general nonadiabatic tunneling. The certain two-state exponential potential models are employed for numerical tests, and the calculations from the present general nonadiabatic tunneling formula are demonstrated in very good agreement with the results from exact quantum mechanical calculations. The present general nonadiabatic tunneling formula can be incorporated with various mixed quantum-classical methods for modeling electronically nonadiabatic processes in photochemistry.
Strong-coupling effects in superfluid 3He in aerogel
International Nuclear Information System (INIS)
Aoyama, Kazushi; Ikeda, Ryusuke
2007-01-01
Effects of impurity scatterings on the strong-coupling (SC) contribution, stabilizing the ABM (axial) pairing state, to the quartic term of the Ginzburg-Landau free energy of superfluid 3 He are theoretically studied to examine recent observations suggestive of an anomalously small SC effect in superfluid 3 He in aerogels. To study the SC corrections, two approaches are used. One is based on a perturbation in the short-range repulsive interaction, and the other is a phenomenological approach used previously for the bulk liquid by Sauls and Serene [Phys. Rev. B 24, 183 (1981)]. It is found that the impurity scattering favors the BW pairing state and shrinks the region of the ABM pairing state in the T-P phase diagram. In the phenomenological approach, the resulting shrinkage of the ABM region is especially substantial and, if assuming an anisotropy over a large scale in aerogel, leads to justifying the phase diagrams determined experimentally
Strong delayed interactive effects of metal exposure and warming
DEFF Research Database (Denmark)
Debecker, Sara; Dinh, Khuong Van; Stoks, Robby
2017-01-01
’ ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and lowlatitude populations. By integrating these mechanisms...... into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis...... was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies...
Effectiveness of Advanced Stay Strong, Stay Healthy in Community Settings
Directory of Open Access Journals (Sweden)
Emily M. Crowe MS
2015-07-01
Full Text Available The goal of this research was to investigate the effectiveness of the 10-week, University of Missouri (MU Extension strength training program Advanced Stay Strong, Stay Healthy (ASSSH. It was hypothesized that the program can improve strength, balance, agility, and flexibility—all physical measures of falling among seniors. Matched pair t tests were used to compare differences in five physical measures of health, body composition, and percent body fat (%BF. Two-way ANOVA was conducted to examine the age effects on changes in physical health from the start and finish of the exercise program. Following programming, participants significantly improved strength, flexibility, and balance, and significantly reduced %BF ( p < .05. Our data indicate that ASSSH can improve the physical health of senior citizens and can successfully be translated into community practice by MU Extension professionals.
Impact of Turbocharger Non-Adiabatic Operation on Engine Volumetric Efficiency and Turbo Lag
Directory of Open Access Journals (Sweden)
S. Shaaban
2012-01-01
Full Text Available Turbocharger performance significantly affects the thermodynamic properties of the working fluid at engine boundaries and hence engine performance. Heat transfer takes place under all circumstances during turbocharger operation. This heat transfer affects the power produced by the turbine, the power consumed by the compressor, and the engine volumetric efficiency. Therefore, non-adiabatic turbocharger performance can restrict the engine charging process and hence engine performance. The present research work investigates the effect of turbocharger non-adiabatic performance on the engine charging process and turbo lag. Two passenger car turbochargers are experimentally and theoretically investigated. The effect of turbine casing insulation is also explored. The present investigation shows that thermal energy is transferred to the compressor under all circumstances. At high rotational speeds, thermal energy is first transferred to the compressor and latter from the compressor to the ambient. Therefore, the compressor appears to be “adiabatic” at high rotational speeds despite the complex heat transfer processes inside the compressor. A tangible effect of turbocharger non-adiabatic performance on the charging process is identified at turbocharger part load operation. The turbine power is the most affected operating parameter, followed by the engine volumetric efficiency. Insulating the turbine is recommended for reducing the turbine size and the turbo lag.
Strong impacts on aerosol indirect effects from historical oxidant changes
Hafsahl Karset, Inger Helene; Koren Berntsen, Terje; Storelvmo, Trude; Alterskjær, Kari; Grini, Alf; Olivié, Dirk; Kirkevåg, Alf; Seland, Øyvind; Iversen, Trond; Schulz, Michael
2018-06-01
Uncertainties in effective radiative forcings through aerosol-cloud interactions (ERFaci, also called aerosol indirect effects) contribute strongly to the uncertainty in the total preindustrial-to-present-day anthropogenic forcing. Some forcing estimates of the total aerosol indirect effect are so negative that they even offset the greenhouse gas forcing. This study highlights the role of oxidants in modeling of preindustrial-to-present-day aerosol indirect effects. We argue that the aerosol precursor gases should be exposed to oxidants of its era to get a more correct representation of secondary aerosol formation. Our model simulations show that the total aerosol indirect effect changes from -1.32 to -1.07 W m-2 when the precursor gases in the preindustrial simulation are exposed to preindustrial instead of present-day oxidants. This happens because of a brightening of the clouds in the preindustrial simulation, mainly due to large changes in the nitrate radical (NO3). The weaker oxidative power of the preindustrial atmosphere extends the lifetime of the precursor gases, enabling them to be transported higher up in the atmosphere and towards more remote areas where the susceptibility of the cloud albedo to aerosol changes is high. The oxidation changes also shift the importance of different chemical reactions and produce more condensate, thus increasing the size of the aerosols and making it easier for them to activate as cloud condensation nuclei.
Strong impacts on aerosol indirect effects from historical oxidant changes
Directory of Open Access Journals (Sweden)
I. H. H. Karset
2018-06-01
Full Text Available Uncertainties in effective radiative forcings through aerosol–cloud interactions (ERFaci, also called aerosol indirect effects contribute strongly to the uncertainty in the total preindustrial-to-present-day anthropogenic forcing. Some forcing estimates of the total aerosol indirect effect are so negative that they even offset the greenhouse gas forcing. This study highlights the role of oxidants in modeling of preindustrial-to-present-day aerosol indirect effects. We argue that the aerosol precursor gases should be exposed to oxidants of its era to get a more correct representation of secondary aerosol formation. Our model simulations show that the total aerosol indirect effect changes from −1.32 to −1.07 W m−2 when the precursor gases in the preindustrial simulation are exposed to preindustrial instead of present-day oxidants. This happens because of a brightening of the clouds in the preindustrial simulation, mainly due to large changes in the nitrate radical (NO3. The weaker oxidative power of the preindustrial atmosphere extends the lifetime of the precursor gases, enabling them to be transported higher up in the atmosphere and towards more remote areas where the susceptibility of the cloud albedo to aerosol changes is high. The oxidation changes also shift the importance of different chemical reactions and produce more condensate, thus increasing the size of the aerosols and making it easier for them to activate as cloud condensation nuclei.
Effective potential kinetic theory for strongly coupled plasmas
Baalrud, Scott D.; Daligault, Jérôme
2016-11-01
The effective potential theory (EPT) is a recently proposed method for extending traditional plasma kinetic and transport theory into the strongly coupled regime. Validation from experiments and molecular dynamics simulations have shown it to be accurate up to the onset of liquid-like correlation parameters (corresponding to Γ ≃ 10-50 for the one-component plasma, depending on the process of interest). Here, this theory is briefly reviewed along with comparisons between the theory and molecular dynamics simulations for self-diffusivity and viscosity of the one-component plasma. A number of new results are also provided, including calculations of friction coefficients, energy exchange rates, stopping power, and mobility. The theory is also cast in the Landau and Fokker-Planck kinetic forms, which may prove useful for enabling efficient kinetic computations.
Surface correlation effects in two-band strongly correlated slabs.
Esfahani, D Nasr; Covaci, L; Peeters, F M
2014-02-19
Using an extension of the Gutzwiller approximation for an inhomogeneous system, we study the two-band Hubbard model with unequal band widths for a slab geometry. The aim is to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab. The main effect of the difference in band width is the presence of two different length scales corresponding to the quasi-particle profile of each band. This is enhanced in the vicinity of the critical interaction of the narrow band where an orbitally selective Mott transition occurs and a surface dead layer forms for the narrow band. For the doped case, two different regimes of charge transfer between the surface and the bulk of the slab are revealed. The charge transfer from surface/center to center/surface depends on both the doping level and the average relative charge accumulated in each band. Such effects could also be of importance when describing the accumulation of charges at the interface between structures made of multi-band strongly correlated materials.
Nonadiabatic effects in inelastic collisional processes
International Nuclear Information System (INIS)
Belyaev, Andrey K
2009-01-01
The standard adiabatic Born-Oppenheimer approach to inelastic collisional processes is revised. It is shown that the widely used standard interpretation of this approach has fundamental limitations leading to physical artefacts or to uncertainties in numerical calculations due to neglecting the electron translation problem. It is demonstrated that the Born-Oppenheimer approach itself does not have such limitations. The particular full quantum solution of the electron translation problem within the Born-Oppenheimer approach by means of the reprojection procedure is discussed in the paper together with the practical applications.
Semiclassical Monte Carlo: A first principles approach to non-adiabatic molecular dynamics
International Nuclear Information System (INIS)
White, Alexander J.; Gorshkov, Vyacheslav N.; Wang, Ruixi; Tretiak, Sergei; Mozyrsky, Dmitry
2014-01-01
Modeling the dynamics of photophysical and (photo)chemical reactions in extended molecular systems is a new frontier for quantum chemistry. Many dynamical phenomena, such as intersystem crossing, non-radiative relaxation, and charge and energy transfer, require a non-adiabatic description which incorporate transitions between electronic states. Additionally, these dynamics are often highly sensitive to quantum coherences and interference effects. Several methods exist to simulate non-adiabatic dynamics; however, they are typically either too expensive to be applied to large molecular systems (10's-100's of atoms), or they are based on ad hoc schemes which may include severe approximations due to inconsistencies in classical and quantum mechanics. We present, in detail, an algorithm based on Monte Carlo sampling of the semiclassical time-dependent wavefunction that involves running simple surface hopping dynamics, followed by a post-processing step which adds little cost. The method requires only a few quantities from quantum chemistry calculations, can systematically be improved, and provides excellent agreement with exact quantum mechanical results. Here we show excellent agreement with exact solutions for scattering results of standard test problems. Additionally, we find that convergence of the wavefunction is controlled by complex valued phase factors, the size of the non-adiabatic coupling region, and the choice of sampling function. These results help in determining the range of applicability of the method, and provide a starting point for further improvement
Measurement of strong interaction effects in antiprotonic helium atoms
International Nuclear Information System (INIS)
Davies, J.D.; Gorringe, T.P.; Lowe, J.; Nelson, J.M.; Playfer, S.M.; Pyle, G.J.; Squier, G.T.A.
1984-01-01
The strong interaction shift and width for the 2 p level and the width for the 3d level have been measured for antiprotonic helium atoms. The results are compared with optical model calculations. The possible existence of strongly bound antiproton states in nuclei is discussed. (orig.)
THE EFFECT OF ENVIRONMENT ON SHEAR IN STRONG GRAVITATIONAL LENSES
International Nuclear Information System (INIS)
Wong, Kenneth C.; Zabludoff, Ann I.; Keeton, Charles R.; Williams, Kurtis A.; Momcheva, Ivelina G.
2011-01-01
Using new photometric and spectroscopic data in the fields of nine strong gravitational lenses that lie in galaxy groups, we analyze the effects of both the local group environment and line-of-sight (LOS) galaxies on the lens potential. We use Monte Carlo simulations to derive the shear directly from measurements of the complex lens environment, providing the first detailed independent check of the shear obtained from lens modeling. We account for possible tidal stripping of the group galaxies by varying the fraction of total mass apportioned between the group dark matter halo and individual group galaxies. The environment produces an average shear of γ = 0.08 (ranging from 0.02 to 0.17), significant enough to affect quantities derived from lens observables. However, the direction and magnitude of the shears do not match those obtained from lens modeling in three of the six four-image systems in our sample (B1422, RXJ1131, and WFI2033). The source of this disagreement is not clear, implying that the assumptions inherent in both the environment and lens model approaches must be reconsidered. If only the local group environment of the lens is included, the average shear is γ = 0.05 (ranging from 0.01 to 0.14), indicating that LOS contributions to the lens potential are not negligible. We isolate the effects of various theoretical and observational uncertainties on our results. Of those uncertainties, the scatter in the Faber-Jackson relation and error in the group centroid position dominate. Future surveys of lens environments should prioritize spectroscopic sampling of both the local lens environment and objects along the LOS, particularly those bright (I< 21.5) galaxies projected within 5' of the lens.
Nonadiabatic heating of the central plasma sheet at substorm onset
International Nuclear Information System (INIS)
Huang, C.Y.; Frank, L.A.; Rostoker, G.; Fennell, J.; Mitchell, D.G.
1992-01-01
Heating events in the plasma sheet boundary layer and central plasma sheet are found to occur at the onset of expansive phase activity. The main effect is a dramatic increase in plasma temperature, coincident with a partial dipolarization of the magnetic field. Fluxes of energetic particles increase without dispersion during these events which occur at all radial distances up to 23 R E , the apogee of the ISEIE spacecraft. A major difference between these heating events and those observed at geosynchronous distances lies in the heating mechanism which is nonadiabatic beyond 10 R E but may be adiabatic closer to Earth. The energy required to account for the increase in plasma thermal energy is comparable with that required for Joule heating of the ionosphere. The plasma sheet must be considered as a major sink in the energy balance of substorm. The authors estimate lobe magnetic pressures during these events. Changes in lobe pressure are generally not correlated with onsets or intensifications of expansive phase activity
Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices
Akosa, Collins Ashu; Ndiaye, Papa Birame; Manchon, Aurelien
2017-01-01
We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.
Intrinsic nonadiabatic topological torque in magnetic skyrmions and vortices
Akosa, Collins Ashu
2017-03-01
We propose that topological spin currents flowing in topologically nontrivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic nonadiabatic torque of the form Tt∼[(∂xm×∂ym)·m]∂ym. We show that this torque, which is absent in one-dimensional domain walls and/or nontopological textures, is responsible for the enhanced nonadiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.
Effect of strong coupling on interfacial electron transfer dynamics in ...
Indian Academy of Sciences (India)
Unknown
regarded as the best sensitizing dyes for solar energy conversion for their strong visible absorption bands, long-lived ... solar cells based on dye-sensitized nanocrystalline. TiO2. High affinity for the TiO2 surface, which is ... pump pulses at 400 nm, one part of 800 nm with. 200 µJ/pulse, is frequency doubled in BBO crystals.
Effective Field Theories and Strong Interactions. Final Technical Report
International Nuclear Information System (INIS)
Fleming, Sean
2011-01-01
The framework of Effective Field Theories (EFTs) allows us to describe strong interactions in terms of degrees of freedom relevant to the energy regimes of interest, in the most general way consistent with the symmetries of QCD. Observables are expanded systematically in powers of M lo /M hi , where M lo (M hi ) denotes a low-(high-)energy scale. This organizational principle is referred to as 'power counting'. Terms of increasing powers in the expansion parameter are referred to as leading order (LO), next-to-leading order (NLO), etc. Details of the QCD dynamics not included explicitly are encoded in interaction parameters, or 'low-energy constants' (LECs), which can in principle be calculated from an explicit solution of QCD - for example via lattice simulations- but can also be determined directly from experimental data. QCD has an intrinsic scale M QCD ≅ 1 GeV, at which the QCD coupling constant α s (M QCD ) becomes large and the dynamics becomes non-perturbative. As a consequence M QCD sets the scale for the masses of most hadrons, such as the nucleon mass m N ≅ 940 MeV. EFTs can roughly be divided into two categories: those that can be matched onto QCD in perturbation theory, which we call high-energy EFTs, and those that cannot be matched perturbatively, which we call low-energy EFTs. In high-energy EFTs, M QCD typically sets the low-energy scale, and all the dynamics associated with this scale reside in matrix elements of EFT operators. These non-perturbative matrix elements are the LECs and are also referred to as long-distance contributions. Each matrix element is multiplied by a short-distance coefficient, which contains the dynamics from the high scale M hi . Since M hi >> M QCD , α s (M hi ) hi ∼ M Q , the heavy-quark mass, and in addition to M QCD there are low scales associated with the typical relative momentum ∼ M Q v and energy ∼ M Q v 2 of the heavy quarks. Depending on the sizes of M Q and the heavy-quark velocity v these scales can
Spectator Effects during Leptogenesis in the Strong Washout Regime
Garbrecht, Bjorn
2014-01-01
By including spectator fields into the Boltzmann equations for Leptogenesis, we show that partially equilibrated spectator interactions can have a significant impact on the freeze-out value of the asymmetry in the strong washout regime. The final asymmetry is typically increased, since partially equilibrated spectators "hide" a part of the asymmetry from washout. We study examples with leptonic and non-leptonic spectator processes, assuming thermal initial conditions, and find up to 50% enhanced asymmetries compared to the limit of fully equilibrated spectators. Together with a comprehensive overview of the equilibration temperatures for various Standard Model processes, the numerical results indicate the ranges when the limiting cases of either fully equilibrated or negligible spectator fields are applicable and when they are not. Our findings also indicate an increased sensitivity to initial conditions and finite density corrections even in the strong washout regime.
How strong and generalisable is the Generation Y effect?
DEFF Research Database (Denmark)
Mueller, Simone; Remaud, Hervé; Chabin, Yann
2011-01-01
Purpose – This study aims to investigate how strongly Generation Y consumers differ in their values, attitudes and wine and alcoholic beverage consumption behaviour from older generations. The comparison spans seven culturally different markets. Design/methodology/approach – Large representative...... alcoholic beverage consumption. A number of noticeable differences appeared between countries: wine involvement and consumption increases with age in traditional European wine markets, while they decrease in North America; environmental concerns and purchase channel usage hardly differ between generations...
Non-adiabatic rotational excitation of dipolar molecule under the ...
Indian Academy of Sciences (India)
J. Chem. Sci. Vol. 125, No. 5, September 2013, pp. 1213–1221. c Indian Academy of Sciences. ... The rotational wave packets of LiCl molecule excited non-adiabatically by half cycle pulse. (HCP) is .... pared to the intensities required for the ionization of ..... out and with delayed ultrashort HCP at different initial pulse dura-.
Nonadiabatic corrections to a quantum dot quantum computer
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 83; Issue 1. Nonadiabatic corrections to a quantum dot quantum computer working in adiabatic limit. M Ávila ... The time of operation of an adiabatic quantum computer must be less than the decoherence time, otherwise the computer would be nonoperative. So far, the ...
Nonadiabatic geometrical quantum gates in semiconductor quantum dots
International Nuclear Information System (INIS)
Solinas, Paolo; Zanghi, Nino; Zanardi, Paolo; Rossi, Fausto
2003-01-01
In this paper, we study the implementation of nonadiabatic geometrical quantum gates with in semiconductor quantum dots. Different quantum information enconding (manipulation) schemes exploiting excitonic degrees of freedom are discussed. By means of the Aharanov-Anandan geometrical phase, one can avoid the limitations of adiabatic schemes relying on adiabatic Berry phase; fast geometrical quantum gates can be, in principle, implemented
Multiphoton above threshold effects in strong-field fragmentation
DEFF Research Database (Denmark)
B Madsen, C; Anis, F; B Madsen, L
2012-01-01
We present a study of multiphoton dissociative ionization from molecules. By solving the time-dependent Schrödinger equation for H2+ and projecting the solution onto double continuum scattering states, we observe the correlated electron-nuclear ionization dynamics in detail. We show—for the first...... time—how multiphoton structure prevails as long as one accounts for the energies of all the fragments. Our current work provides a new avenue to analyze strong-field fragmentation that leads to a deeper understanding of the correlated molecular dynamics....
Spin effects in strong-field laser-electron interactions
International Nuclear Information System (INIS)
Ahrens, S; Bauke, H; Müller, T-O; Villalba-Chávez, S; Müller, C
2013-01-01
The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.
Non - Adiabaticity and Novel Isotope Effect in the Doped Cuprates
International Nuclear Information System (INIS)
Kresin, V.; WOLF, S. A.
1995-01-01
This paper reports a novel isotope effect which is due to a strong non-adiabaticity that manifests itself in the dependence of the carrier concentration on the isotopic mass. The critical temperature in turn depends on the carrier concentration giving rise to a unique and non-phononic isotope shift. (author)
Non-adiabatic description of proton emission from the odd-odd nucleus 130Eu
Directory of Open Access Journals (Sweden)
Patial Monika
2014-03-01
Full Text Available We discuss the non-adiabatic quasiparticle approach for calculating the rotational spectra and decay width of odd-odd proton emitters. The Coriolis effects are incorporated in both the parent and daughter wave functions. Results for the two probable ground states (1+ and 2+ of the proton emitter 130Eu are discussed. With our calculations, we confirm the proton emitting state to be the Iπ = 1+ state, irrespective of the strength of the Coriolis interaction. This study provides us with an opportunity to look into the details of wave functions of deformed odd-odd nuclei to which the proton emission halflives are quite sensitive.
Radiation effects on relativistic electrons in strong external fields
International Nuclear Information System (INIS)
Iqbal, Khalid
2013-01-01
The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.
Effective magnetic moment of neutrinos in strong magnetic fields
International Nuclear Information System (INIS)
Perez M, A.; Perez R, H.; Masood, S.S.; Gaitan, R.; Rodriguez R, S.
2002-01-01
In this paper we compute the effective magnetic moment of neutrinos propagating in dense high magnetized medium. Taking typical values of magnetic field and densities of astrophysical objects (such as the cores of supernovae and neutron stars) we obtain an effective type of dipole magnetic moment in agreement with astrophysical and cosmological bounds. (Author)
The Connect Effect Building Strong Personal, Professional, and Virtual Networks
Dulworth, Michael
2008-01-01
Entrepreneur and executive development expert Mike Dulworth's THE CONNECT EFFECT provides readers with a simple framework and practical tools for developing that crucial competitive advantage: a high-quality personal, professional/organizational and virtual network.
Strong effects of ionizing radiation from Chernobyl on mutation rates
M?ller, Anders Pape; Mousseau, Timothy A.
2015-01-01
In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null...
Multiple coupled landscapes and non-adiabatic dynamics with applications to self-activating genes.
Chen, Cong; Zhang, Kun; Feng, Haidong; Sasai, Masaki; Wang, Jin
2015-11-21
Many physical, chemical and biochemical systems (e.g. electronic dynamics and gene regulatory networks) are governed by continuous stochastic processes (e.g. electron dynamics on a particular electronic energy surface and protein (gene product) synthesis) coupled with discrete processes (e.g. hopping among different electronic energy surfaces and on and off switching of genes). One can also think of the underlying dynamics as the continuous motion on a particular landscape and discrete hoppings among different landscapes. The main difference of such systems from the intra-landscape dynamics alone is the emergence of the timescale involved in transitions among different landscapes in addition to the timescale involved in a particular landscape. The adiabatic limit when inter-landscape hoppings are fast compared to continuous intra-landscape dynamics has been studied both analytically and numerically, but the analytical treatment of the non-adiabatic regime where the inter-landscape hoppings are slow or comparable to continuous intra-landscape dynamics remains challenging. In this study, we show that there exists mathematical mapping of the dynamics on 2(N) discretely coupled N continuous dimensional landscapes onto one single landscape in 2N dimensional extended continuous space. On this 2N dimensional landscape, eddy current emerges as a sign of non-equilibrium non-adiabatic dynamics and plays an important role in system evolution. Many interesting physical effects such as the enhancement of fluctuations, irreversibility, dissipation and optimal kinetics emerge due to non-adiabaticity manifested by the eddy current illustrated for an N = 1 self-activator. We further generalize our theory to the N-gene network with multiple binding sites and multiple synthesis rates for discretely coupled non-equilibrium stochastic physical and biological systems.
Strange effects of strong high-frequency excitation
DEFF Research Database (Denmark)
Thomsen, Jon Juel
2003-01-01
Three general effects of mechanical high-frequency excitation (HFE) are described: Stiffening - an apparent change in the stiffness associated with an equilibrium; Biasing - a tendency for a system to move towards a particular state which does not exist or is unstable without HFE; and Smoothening...
Effective bounds on strong unicity in L1-approximation
DEFF Research Database (Denmark)
Kohlenbach, Ulrich; Oliva, Paulo B.
In this paper we present another case study in the general project of Proof Mining which means the logical analysis of prima facie non-effective proofs with the aim of extracting new computationally relevant data. We use techniques based on monotone functional interpretation (developed in [17]) t...
Thermodynamics of strong coupling superconductors including the effect of anisotropy
Daams, J. M.; Carbotte, J. P.
1981-05-01
The thermodynamics of several elemental superconductors is computed from isotropic Eliashberg theory formulated on the imaginary frequency axis. A symmary of the available experimental literature is presented and a comparison with theory is given. The small disagreements that are found are all in the direction expected from anisotropy effects. We calculate the effect of a small amount of model anisotropy on the critical temperature, critical field, and high-temperature specific heat from an exact solution of the anisotropic Eliashberg equations. These are the first such results below the critical temperature; unlike previous analytical work, we include retardation, anisotropy in the mass enhancement, and the effect of the Coulomb repulsion in enhancing anisotropy, all of which are significant. We derive a new formula independent of any model anisotropy for the rate of decrease with impurity lifetime of the critical temperature. Finally we demonstrate how the commonly used formulas of Markowitz and Kadanoff and of Clem may give entirely misleading estimates of the gap anisotropy when used to interpret certain experiments.
Energy Technology Data Exchange (ETDEWEB)
Shit, Anindita [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Ray Chaudhuri, Jyotipratim, E-mail: jprc_8@yahoo.com [Department of Physics, Katwa College, Katwa, Burdwan 713130 (India)
2014-03-18
Highlights: • Nonadiabatic dynamics of quantum particle under the impact of high-frequency force. • Formulation of time-independent dynamics via Floquet and Kapitza schemes. • Manipulation of external force parameters allows us to control the escape rate. • Increase of (amplitudes/frequency) causes the system to decay faster, in general. • Crossover temperature increases in the presence of the field. - Abstract: Escape under the action of the external modulation constitutes a nontrivial generalization of an conventional Kramers rate because the system is away from thermal equilibrium. A derivation of this result from the point of view of Langevin dynamics in the frame of Floquet theorem in conjunction with the Kapitza–Landau time window (that leads to an attractive description of the time-dependent quantum dynamics in terms of time-independent one) has been provided. The quantum escape rate in the intermediate-to-high and very-high damping regime so obtained analytically using the phase space formalism associated with the Wigner distribution and path-integral formalism bears a quantum correction that depends strongly on the barrier height. It is shown that an increase of (amplitude/frequency) ratio causes the system to decay faster, in general. The crossover temperature between tunneling and thermal activation increases in the presence of field so that quantum effects in the escape are relevant at higher temperatures.
Effect of strong fragrance on olfactory detection threshold.
Fasunla, Ayotunde James; Douglas, David Dayo; Adeosun, Aderemi Adeleke; Steinbach, Silke; Nwaorgu, Onyekwere George Benjamin
2014-09-01
To assess the olfactory threshold of healthy volunteers at the University College Hospital, Ibadan and to investigate the effect of perfume on their olfactory detection thresholds. A quasi-experimental study on olfactory detection thresholds of healthy volunteers from September 2013 to November 2013. Tertiary health institution. A structured questionniare was administered to the participants in order to obtain information on sociodemographics, occupation, ability to perceive smell, use of perfume, effects of perfume on appetite and self-confidence, history of allergy, and previous nasal surgery. Participants subjectively rated their olfactory performance. Subsequently, they had olfactory detection threshold testing done at baseline and after exposure to perfume with varied concentrations of n-butanol in a forced triple response and staircase fashion. Healthy volunteers, 37 males and 63 females, were evaluated. Their ages ranged from 19 to 59 years with a mean of 31 years ± 8. Subjectively, 94% of the participants had excellent olfactory function. In the pre-exposure forced triple response, 88% were able to detect the odor at ≤.25 mmol/l concentration while in the post-exposure forced triple response, only 66% were able to detect the odor at ≤.25 mmol/l concentration. There is also a statistical significant difference in the olfactory detection threshold score between the pre-exposure and post-exposure period in the participants (P fragrances affects the olfactory detection threshold. Therefore patients and clinicians should be aware of this and its effects on the outcome of test of olfaction. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2014.
Boguslavskiy, Andrey E.; Schalk, Oliver; Gador, Niklas; Glover, William J.; Mori, Toshifumi; Schultz, Thomas; Schuurman, Michael S.; Martínez, Todd J.; Stolow, Albert
2018-04-01
The ultrafast excited state dynamics of the smallest polyene, trans-1,3-butadiene, were studied by femtosecond time-resolved photoelectron-photoion coincidence (TRPEPICO) spectroscopy. The evolution of the excited state wavepacket, created by pumping the bright 1Bu (ππ*) electronic state at its origin of 216 nm, is projected via one- and two-photon ionization at 267 nm onto several ionization continua. The results are interpreted in terms of Koopmans' correlations and Franck-Condon factors for the excited and cationic states involved. The known predissociative character of the cation excited states is utilized to assign photoelectron bands to specific continua using TRPEPICO spectroscopy. This permits us to report the direct observation of the famously elusive S1(21Ag) dark electronic state during the internal conversion of trans 1,3-butadiene. Our phenomenological analysis permits the spectroscopic determination of several important time constants. We report the overall decay lifetimes of the 11Bu and 21Ag states and observe the re-appearance of the hot ground state molecule. We argue that the apparent dephasing time of the S2(11Bu) state, which leads to the extreme breadth of the absorption spectrum, is principally due to large amplitude torsional motion on the 1Bu surface in conjunction with strong non-adiabatic couplings via conical intersections, whereupon nuclear wavepacket revivals to the initial Franck-Condon region become effectively impossible. In Paper II [W. J. Glover et al., J. Chem. Phys. 148, 164303 (2018)], ab initio multiple spawning is used for on-the-fly computations of the excited state non-adiabatic wavepacket dynamics and their associated TRPEPICO observables, allowing for direct comparisons of experiment with theory.
Strong crystal field effect in ? - optical absorption study
Gajek, Z.; Krupa, J. C.
1998-12-01
=-1 Results of optical absorption measurements in polarized light on tetravalent neptunium diluted in a 0953-8984/10/50/021/img6 single crystal are reported. The recorded spectra are complex, pointing to the presence of an 0953-8984/10/50/021/img7 impurity. The electronic transitions assigned to the 0953-8984/10/50/021/img8 ion are interpreted in terms of the usual model, following the actual understanding of the neptunium electronic structure and independent theoretical predictions. R.m.s. deviations of the order of 0953-8984/10/50/021/img9 have been obtained for 42 levels fitted with 11 free parameters. The crystal field effect resulting from the fitting is considerably larger than that observed for the uranium ion in the same host.
Mendieta-Moreno, Jesús I; Trabada, Daniel G; Mendieta, Jesús; Lewis, James P; Gómez-Puertas, Paulino; Ortega, José
2016-11-03
The absorption of ultraviolet radiation by DNA may result in harmful genetic lesions that affect DNA replication and transcription, ultimately causing mutations, cancer, and/or cell death. We analyze the most abundant photochemical reaction in DNA, the cyclobutane thymine dimer, using hybrid quantum mechanics/molecular mechanics (QM/MM) techniques and QM/MM nonadiabatic molecular dynamics. We find that, due to its double helix structure, DNA presents a free energy barrier between nonreactive and reactive conformations leading to the photolesion. Moreover, our nonadiabatic simulations show that most of the photoexcited reactive conformations return to standard B-DNA conformations after an ultrafast nonradiative decay to the ground state. This work highlights the importance of dynamical effects (free energy, excited-state dynamics) for the study of photochemical reactions in biological systems.
DEFF Research Database (Denmark)
Denisov, S.; Flach, S.; Ovchinnikov, A. A.
2002-01-01
We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries, which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response is em...... is employed to explain the effect. We consider a case of a particle in a periodic potential as an example and discuss the relevant symmetry breakings and the mechanisms of rectification of the current in such a system.......We consider low-dimensional dynamical systems exposed to a heat bath and to additional ac fields. The presence of these ac fields may lead to a breaking of certain spatial or temporal symmetries, which in turn cause nonzero averages of relevant observables. Nonlinear (non)adiabatic response...
On the Magnitude of the Nonadiabatic Error for Highly Coupled Radicals
Stanton, J. F.
2009-06-01
A review is given of recent advances in the construction of (quasi)diabatic model Hamiltonians and their application to analyzing the spectroscopy of molecules with strong vibronic coupling. A numerical application to the vibronic levels of the BNB radical below 0.6 eV is presented, together with corresponding adiabatic (quantum chemistry) calculations. The agreement with the experimental levels is nearly quantitative with the model Hamiltonian, attesting to the power of the approach. On the contrary, it is also revealed that the magnitude of the nonadiabatic contributions to the zero-point energy and the lowest fundamental frequency of the coupling mode are considerably larger than expected, at least by your narrator.
Matsuoka, Takahide; Takatsuka, Kazuo
2017-04-07
A theory for dynamics of molecular photoionization from nonadiabatic electron wavepackets driven by intense pulse lasers is proposed. Time evolution of photoelectron distribution is evaluated in terms of out-going electron flux (current of the probability density of electrons) that has kinetic energy high enough to recede from the molecular system. The relevant electron flux is in turn evaluated with the complex-valued electronic wavefunctions that are time evolved in nonadiabatic electron wavepacket dynamics in laser fields. To uniquely rebuild such wavefunctions with its electronic population being lost by ionization, we adopt the complex-valued natural orbitals emerging from the electron density as building blocks of the total wavefunction. The method has been implemented into a quantum chemistry code, which is based on configuration state mixing for polyatomic molecules. Some of the practical aspects needed for its application will be presented. As a first illustrative example, we show the results of hydrogen molecule and its isotope substitutes (HD and DD), which are photoionized by a two-cycle pulse laser. Photon emission spectrum associated with above threshold ionization is also shown. Another example is taken from photoionization dynamics from an excited state of a water molecule. Qualitatively significant effects of nonadiabatic interaction on the photoelectron spectrum are demonstrated.
Energy Technology Data Exchange (ETDEWEB)
Castro, A., E-mail: acastro@bifi.es [Institute for Biocomputation and Physics of Complex Systems (BIFI) and Zaragoza Scientific Center for Advanced Modelling (ZCAM), University of Zaragoza, 50018 Zaragoza (Spain); Isla, M. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47005 Valladolid (Spain); Martinez, Jose I. [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, ES-28049 Madrid (Spain); Alonso, J.A. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, 47005 Valladolid (Spain)
2012-05-03
Graphical abstract: Two trajectories for the collision of a proton with the Lithium tetramer. On the left, the proton is scattered away, and a Li{sub 2} molecule plus two isolated Lithium atoms result. On the right, the proton is captured and a LiH molecule is created. Highlights: Black-Right-Pointing-Pointer Scattering of a proton with Lithium clusters described from first principles. Black-Right-Pointing-Pointer Description based on non-adiabatic molecular dynamics. Black-Right-Pointing-Pointer The electronic structure is described with time-dependent density-functional theory. Black-Right-Pointing-Pointer The method allows to discern reaction channels depending on initial parameters. - Abstract: We have employed non-adiabatic molecular dynamics based on time-dependent density-functional theory to characterize the scattering behavior of a proton with the Li{sub 4} cluster. This technique assumes a classical approximation for the nuclei, effectively coupled to the quantum electronic system. This time-dependent theoretical framework accounts, by construction, for possible charge transfer and ionization processes, as well as electronic excitations, which may play a role in the non-adiabatic regime. We have varied the incidence angles in order to analyze the possible reaction patterns. The initial proton kinetic energy of 10 eV is sufficiently high to induce non-adiabatic effects. For all the incidence angles considered the proton is scattered away, except in one interesting case in which one of the Lithium atoms captures it, forming a LiH molecule. This theoretical formalism proves to be a powerful, effective and predictive tool for the analysis of non-adiabatic processes at the nanoscale.
Nonadiabatic quantum Vlasov equation for Schwinger pair production
International Nuclear Information System (INIS)
Kim, Sang Pyo; Schubert, Christian
2011-01-01
Using Lewis-Riesenfeld theory, we derive an exact nonadiabatic master equation describing the time evolution of the QED Schwinger pair-production rate for a general time-varying electric field. This equation can be written equivalently as a first-order matrix equation, as a Vlasov-type integral equation, or as a third-order differential equation. In the last version it relates to the Korteweg-de Vries equation, which allows us to construct an exact solution using the well-known one-soliton solution to that equation. The case of timelike delta function pulse fields is also briefly considered.
Non-adiabatic study of the Kepler subgiant KIC 6442183
Directory of Open Access Journals (Sweden)
Grosjean M.
2015-01-01
Full Text Available Thanks to the precision of Kepler observations, [3] were able to measure the linewidth and amplitude of individual modes (including mixed modes in several subgiant power spectra. We perform a forward modelling of a Kepler subgiant based on surface properties and observed frequencies. Non-adiabatic computations including a time- dependent treatment of convection give the lifetimes of radial and non-radial modes. Next, combining the lifetimes and inertias with a stochastic excitation model gives the amplitudes of the modes. We can now directly compare theoretical and observed linewidths and amplitudes of mixed-modes to obtain new constraints on our theoretical models.
International Nuclear Information System (INIS)
Auluck, S.K.H.
1982-01-01
A method of treating problems involving strongly nonadiabatic particle orbits in a magnetic field is described for the case when the system is long-lived on the collisional time scale. A canonical distribution P=Z -1 exp-β(H+Ωpsub(theta)) results from maximization of entropy subject to conservation of the Hamiltonian H and canonical angular momentum psub(theta) for an azimuthally symmetric system. By taking the MIGMA problem as an example, the method of determining the constants β,Ω,Z from the average energy, average angular momentum and the total number of particles is illustrated. Associated physical effects are discussed. (author)
Nonadiabatic Berry phase in nanocrystalline magnets
Directory of Open Access Journals (Sweden)
R. Skomski
2017-05-01
Full Text Available It is investigated how a Berry phase is created in polycrystalline nanomagnets and how the phase translates into an emergent magnetic field and into a topological Hall-effect contribution. The analysis starts directly from the spin of the conduction electrons and does not involve any adiabatic Hamiltonian. Completely random spin alignment in the nanocrystallites does not lead to a nonzero emergent field, but a modulation of the local magnetization does. As an explicit example, we consider a wire with a modulated cone angle.
Nonadiabatic exchange dynamics during adiabatic frequency sweeps.
Barbara, Thomas M
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging. Copyright © 2016 Elsevier Inc. All rights reserved.
The quantum Zeno and anti-Zeno effects with strong system-environment coupling.
Chaudhry, Adam Zaman
2017-05-11
To date, studies of the quantum Zeno and anti-Zeno effects focus on quantum systems that are weakly interacting with their environment. In this paper, we investigate what happens to a quantum system under the action of repeated measurements if the quantum system is strongly interacting with its environment. We consider as the quantum system a single two-level system coupled strongly to a collection of harmonic oscillators. A so-called polaron transformation is then used to make the problem in the strong system-environment coupling regime tractable. We find that the strong coupling case exhibits quantitative and qualitative differences as compared with the weak coupling case. In particular, the effective decay rate does not depend linearly on the spectral density of the environment. This then means that, in the strong coupling regime that we investigate, increasing the system-environment coupling strength can actually decrease the effective decay rate. We also consider a collection of two-level atoms coupled strongly with a common environment. In this case, we find that there are further differences between the weak and strong coupling cases since the two-level atoms can now indirectly interact with one another due to the common environment.
Nontrivial effects of high-frequency excitation for strongly damped mechanical systems
DEFF Research Database (Denmark)
Fidlin, Alexander; Thomsen, Jon Juel
2008-01-01
Some non-trivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based on a slightly...... modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical optimally...
Nontrivial effects of high-frequency excitation for strongly damped mechanical systems
DEFF Research Database (Denmark)
Fidlin, Alexander; Thomsen, Jon Juel
Some nontrivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial (depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based...... on a slightly modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical...
Observational tests of non-adiabatic Chaplygin gas
Energy Technology Data Exchange (ETDEWEB)
Carneiro, S.; Pigozzo, C., E-mail: saulo.carneiro@pq.cnpq.br, E-mail: cpigozzo@ufba.br [Instituto de Física, Universidade Federal da Bahia, Campus de Ondina, Salvador, BA 40210-340 (Brazil)
2014-10-01
In a previous paper [1] it was shown that any dark sector model can be mapped into a non-adiabatic fluid formed by two interacting components, one with zero pressure and the other with equation-of-state parameter ω = -1. It was also shown that the latter does not cluster and, hence, the former is identified as the observed clustering matter. This guarantees that the dark matter power spectrum does not suffer from oscillations or instabilities. It applies in particular to the generalised Chaplygin gas, which was shown to be equivalent to interacting models at both background and perturbation levels. In the present paper we test the non-adiabatic Chaplygin gas against the Hubble diagram of type Ia supernovae, the position of the first acoustic peak in the anisotropy spectrum of the cosmic microwave background and the linear power spectrum of large scale structures. We consider two different compilations of SNe Ia, namely the Constitution and SDSS samples, both calibrated with the MLCS2k2 fitter, and for the power spectrum we use the 2dFGRS catalogue. The model parameters to be adjusted are the present Hubble parameter, the present matter density and the Chaplygin gas parameter α. The joint analysis best fit gives α ≈ - 0.5, which corresponds to a constant-rate energy flux from dark energy to dark matter, with the dark energy density decaying linearly with the Hubble parameter. The ΛCDM model, equivalent to α = 0, stands outside the 3σ confidence interval.
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Thomsen, Jon Juel; Snaeland, Sveinn Orri
2008-01-01
The aim of this article is to investigate how highfrequency (HF) excitation, combined with strong nonlinear elastic material behavior, influences the effective material or structural properties for low-frequency excitation and wave propagation. The HF effects are demonstrated on discrete linear s...
Line-of-sight effects in strong lensing: putting theory into practice
Energy Technology Data Exchange (ETDEWEB)
Birrer, Simon; Welschen, Cyril; Amara, Adam; Refregier, Alexandre, E-mail: simon.birrer@phys.ethz.ch, E-mail: cyril.welschen@student.ethz.ch, E-mail: adam.amara@phys.ethz.ch, E-mail: alexandre.refregier@phys.ethz.ch [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich (Switzerland)
2017-04-01
We present a simple method to accurately infer line of sight (LOS) integrated lensing effects for galaxy scale strong lens systems through image reconstruction. Our approach enables us to separate weak lensing LOS effects from the main strong lens deflector. We test our method using mock data and show that strong lens systems can be accurate probes of cosmic shear with a precision on the shear terms of ± 0.003 (statistical error) for an HST-like dataset. We apply our formalism to reconstruct the lens COSMOS 0038+4133 and its LOS. In addition, we estimate the LOS properties with a halo-rendering estimate based on the COSMOS field galaxies and a galaxy-halo connection. The two approaches are independent and complementary in their information content. We find that when estimating the convergence at the strong lens system, performing a joint analysis improves the measure by a factor of two compared to a halo model only analysis. Furthermore the constraints of the strong lens reconstruction lead to tighter constraints on the halo masses of the LOS galaxies. Joint constraints of multiple strong lens systems may add valuable information to the galaxy-halo connection and may allow independent weak lensing shear measurement calibrations.
Energy Technology Data Exchange (ETDEWEB)
Bandyopadhyay, P. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)], E-mail: pintu@ipr.res.in; Prasad, G.; Sen, A.; Kaw, P.K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2007-09-03
The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO{sub 2} dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of {partial_derivative}{omega}/{partial_derivative}k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.
International Nuclear Information System (INIS)
Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P.K.
2007-01-01
The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO 2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust-dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects
Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.
2007-09-01
The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and MnO2 dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of ∂ω/∂k<0 are identified as signatures of dust dust correlations. In the high collisional regime dust neutral collisions produce a similar effect and prevent an unambiguous identification of strong coupling effects.
Dust acoustic solitary and shock waves in strongly coupled dusty ...
Indian Academy of Sciences (India)
between nonlinear and dispersion effects can result in the formation of symmetrical solitary waves. Also shock ... et al have studied the effect of nonadiabatic dust charge variation on the nonlinear dust acoustic wave with ..... Figure 5 presents the border between oscillatory- and monotonic-type shock waves as functions of ...
Engineering the Dynamics of Effective Spin-Chain Models for Strongly Interacting Atomic Gases
DEFF Research Database (Denmark)
Volosniev, A. G.; Petrosyan, D.; Valiente, M.
2015-01-01
We consider a one-dimensional gas of cold atoms with strong contact interactions and construct an effective spin-chain Hamiltonian for a two-component system. The resulting Heisenberg spin model can be engineered by manipulating the shape of the external confining potential of the atomic gas. We...
Non-Oberbeck-Boussinesq effects in strongly turbulent Rayleigh-Bénard convection
Ahlers, Günter; Brown, Eric; Fontenele Araujo Junior, F.; Funfschilling, Denis; Grossmann, Siegfried; Lohse, Detlef
2006-01-01
Non-Oberbeck–Boussinesq (NOB) effects on the Nusselt number $Nu$ and Reynolds number $\\hbox{\\it Re}$ in strongly turbulent Rayleigh–Bénard (RB) convection in liquids were investigated both experimentally and theoretically. In the experiments the heat current, the temperature difference, and the
Room temperature strong coupling effects from single ZnO nanowire microcavity
Das, Ayan; Heo, Junseok; Bayraktaroglu, Adrian; Guo, Wei; Ng, Tien Khee; Phillips, Jamie; Ooi, Boon S.; Bhattacharya, Pallab
2012-01-01
Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non
Effects of interaction imbalance in a strongly repulsive one-dimensional Bose gas
DEFF Research Database (Denmark)
Barfknecht, Rafael Emilio; Zinner, Nikolaj Thomas; Foerster, Angela
2018-01-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate...
Heavy quark mass effects and improved tests of the flavor independence of strong interactions
Energy Technology Data Exchange (ETDEWEB)
Burrows, P.N. [Univ. of Oxford (United Kingdom); SLD Collaboration
1998-08-01
A review is given of latest results on tests of the flavor independence of strong interactions. Heavy quark mass effects are evident in the data and are now taken into account at next-to-leading order in QCD perturbation theory. The strong-coupling ratios {alpha}{sub s}{sup b}/{alpha}{sub s}{sup uds} and {alpha}{sub s}{sup c}/{alpha}{sub s}{sup uds} are found to be consistent with unity. Determinations of the b-quark mass m{sub b} (M{sub Z}) are discussed.
Classical anomalous absorption in strongly magnetized plasmas and effective shielding length
International Nuclear Information System (INIS)
Matsuda, K.
1981-01-01
The high-frequency conductivity tensor of a plasma in a magnetic field has been evaluated. An anomalous perpendicular conductivity is obtained for a strongly magnetized plasma. Contrarily to the previous prediction, the effective shielding length is found to be the Debye length even when the Debye length is larger than the electron gyroradius. The effective shielding length is further discussed by presenting the generalized Balescu-Lenard equation
Effects of Interaction Imbalance in a Strongly Repulsive One-Dimensional Bose Gas
Barfknecht, R. E.; Foerster, A.; Zinner, N. T.
2018-05-01
We calculate the spatial distributions and the dynamics of a few-body two-component strongly interacting Bose gas confined to an effectively one-dimensional trapping potential. We describe the densities for each component in the trap for different interaction and population imbalances. We calculate the time evolution of the system and show that, for a certain ratio of interactions, the minority population travels through the system as an effective wave packet.
Instanton and tensor-force effects in the strong decays of mesons
International Nuclear Information System (INIS)
Bonnaz, R.; Silvestre-Brac, B.
2001-01-01
The strong decays of mesons are studied in the framework of the 3 P 0 model with a momentum-dependent vertex. The mesons wave functions are obtained from quark-antiquark potentials including a finite quark size, instanton effects, spin-orbit and tensor-force effects. Several prescriptions for treating the decays into three mesons are proposed and analyzed. Comparison to experimental data is presented in detail. (author)
Quasi-particles and effective mean field in strongly interacting matter
International Nuclear Information System (INIS)
Levai, P.; Ko, C.M.
2010-01-01
We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar σ field by introducing a dynamically generated mass, M(σ), and a self-consistently determined interaction term, B(σ). We display a possible connection between the two types of effective description, using the Friedberg-Lee model.
International Nuclear Information System (INIS)
Abadli, S.; Mansour, F.
2011-01-01
This work deals with the investigation of the complex phenomenon of boron (B) transient enhanced diffusion (TED) in strongly implanted silicon (Si) layers. It concerns the instantaneous influences of the strong B concentrations, the Si layers crystallization, the clustering and the B trapping/segregation during thermal post-implantation annealing. We have used Si thin layers obtained from disilane (Si2H6) by low pressure chemical vapor deposition (LPCVD) and then B implanted with a dose of 4 x 1015 atoms/cm2 at an energy of 15 keV. To avoid long redistributions, thermal annealing was carried out at relatively low-temperatures (700, 750 and 800 'deg'C) for various short-times ranging between 1 and 30 minutes. To investigate the experimental secondary ion mass spectroscopy (SIMS) doping profiles, a redistribution model well adapted to the particular structure of Si-LPCVD layers and to the effects of strong-concentrations has been established. The good adjustment of the simulated profiles with the experimental SIMS profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the TED process in strongly doped Si-LPCVD layers. It was found that boron TED is strongly affected by the simultaneous complex kinetics of clustering, crystallization, trapping and segregation during annealing. The fast formation of small Si-B clusters enhances the B diffusivity whereas the evolution of the clusters and segregation reduce this enhancement. (author)
Energy Technology Data Exchange (ETDEWEB)
Taioli, Simone [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Chemistry, University of Bologna, Bologna (Italy); Garberoglio, Giovanni [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Simonucci, Stefano [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Physics, University of Camerino, Camerino (Italy); Beccara, Silvio a [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Physics, University of Trento, Trento (Italy); Aversa, Lucrezia [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Nardi, Marco [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Trento (Italy); Institut fuer Physik, Humboldt-Universitaet zu Berlin, Berlin (Germany); Verucchi, Roberto [Institute of Materials for Electronics and Magnetism, FBK-CNR, Trento (Italy); Iannotta, Salvatore [Institute of Materials for Electronics and Magnetism, IMEM-CNR, Parma (Italy); Dapor, Maurizio [Interdisciplinary Laboratory for Computational Science, FBK-Center for Materials and Microsystems and University of Trento, Trento (Italy); Department of Materials Engineering and Industrial Technologies, University of Trento, Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Padova (Italy); and others
2013-01-28
In this work, we investigate the processes leading to the room-temperature growth of silicon carbide thin films by supersonic molecular beam epitaxy technique. We present experimental data showing that the collision of fullerene on a silicon surface induces strong chemical-physical perturbations and, for sufficient velocity, disruption of molecular bonds, and cage breaking with formation of nanostructures with different stoichiometric character. We show that in these out-of-equilibrium conditions, it is necessary to go beyond the standard implementations of density functional theory, as ab initio methods based on the Born-Oppenheimer approximation fail to capture the excited-state dynamics. In particular, we analyse the Si-C{sub 60} collision within the non-adiabatic nuclear dynamics framework, where stochastic hops occur between adiabatic surfaces calculated with time-dependent density functional theory. This theoretical description of the C{sub 60} impact on the Si surface is in good agreement with our experimental findings.
Nonadiabatic charged spherical evolution in the postquasistatic approximation
International Nuclear Information System (INIS)
Rosales, L.; Barreto, W.; Peralta, C.; Rodriguez-Mueller, B.
2010-01-01
We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of dissipative and electrically charged distributions in general relativity. The numerical implementation of our approach leads to a solver which is globally second-order convergent. We evolve nonadiabatic distributions assuming an equation of state that accounts for the anisotropy induced by the electric charge. Dissipation is described by streaming-out or diffusion approximations. We match the interior solution, in noncomoving coordinates, with the Vaidya-Reissner-Nordstroem exterior solution. Two models are considered: (i) a Schwarzschild-like shell in the diffusion limit; and (ii) a Schwarzschild-like interior in the free-streaming limit. These toy models tell us something about the nature of the dissipative and electrically charged collapse. Diffusion stabilizes the gravitational collapse producing a spherical shell whose contraction is halted in a short characteristic hydrodynamic time. The streaming-out radiation provides a more efficient mechanism for emission of energy, redistributing the electric charge on the whole sphere, while the distribution collapses indefinitely with a longer hydrodynamic time scale.
Determination of lifetimes and nonadiabatic correlations from measured dipole polarizabilities
International Nuclear Information System (INIS)
Curtis, Lorenzo J
2007-01-01
In atomic systems for which the total oscillator strength of excitations from the ground state is dominated by the transition to the lowest resonance level, the f-sum rule provides a bracketing inequality connecting the lifetime τ of that level to the dipole polarizability α d . This relationship has been used previously to deduce α d from τ. It is shown here that improved spectroscopic accuracies now permit this procedure to be inverted, with τ deduced from a value for α d obtained spectroscopically using the core polarization model. A similar quantitative relationship exists connecting the nonadiabatic correlation factor β to τ, and thus also to α d . The method is applied to a recent measurement of α d for Kr 6+ to obtain the values τ(4s4p 1 P 1 ) 0.096 ± 0.003 ns and β(Kr 6+ ) = 1.71 ± 0.03a 5 0 . It is shown that the use of this method to make precision lifetime determinations for a small number of ions in an isoelectronic sequence permits the exploitation of observed semiempirical regularities to specify the lifetimes of all ions in that sequence
Nonadiabatic two-electron transfer mediated by an irregular bridge
International Nuclear Information System (INIS)
Petrov, E.G.; Shevchenko, Ye.V.; May, V.
2004-01-01
Nonadiabatic two-electron transfer (TET) mediated by a linear molecular bridge is studied theoretically. Special attention is put on the case of a irregular distribution of bridge site energies as well as on the inter-site Coulomb interaction. Based on the unified description of electron transfer reactions [J. Chem. Phys. 115 (2001) 7107] a closed set of kinetic equations describing the TET process is derived. A reduction of this set to a single exponential donor-acceptor (D-A) TET is performed together with a derivation of an overall D-A TET rate. The latter contains a contribution of the stepwise as well as of the concerted route of D-A TET. The stepwise contribution is determined by two single-electron steps each of them associated with a sequential and a superexchange pathway. A two-electron unistep superexchange transition between the D and A forms the concerted contribution to the overall rate. Both contributions are analyzed in their dependency on the bridge length. The irregular distribution of the bridge site energies as well as the influence of the Coulomb interaction facilitates the D-A TET via a modification of the stepwise and the concerted part of the overall rate. At low temperatures and for short bridges with a single or two units the concerted contribution exceeds the stepwise contribution. If the bridge contains more than two units, the stepwise contribution dominates the overall rate
Generation of helical electron beams by a nonadiabatic gun
International Nuclear Information System (INIS)
Barroso, J.J.; Stellati, C.
1996-01-01
The design of a non-adiabatic gun to produce a 10A, 50kV hollow laminar electron beam for gyrotron applications is reported. The beam is extracted from the emitting ring in a direction parallel to the axial guide magnetic field and then propagates across the radial electric field in the anode gap. The electrons are thereby given a transverse velocity upon passing through the modulation anode region where an electrostatic pumping mechanism takes place, so that a considerable amount of the electron energy is converted to transverse kinetic energy. Such a beam extraction method gives rise to favourable features that are examined throughout the work. The dynamics of hollow electron beams with gyromotion propagating down a cylindrical drift tube are also analysed. Due to the action of the beam's self-space charge field, the transverse velocity spread has an oscillatory behaviour along the drift tube wherein the spatial automodulation period shortens with increasing current. Numerical simulation results indicate that even at a 10A beam current, the resulting transverse velocity spread is still less than the spread for a zero beam current. (UK)
Nonadiabatic dynamics of electron injection into organic molecules
International Nuclear Information System (INIS)
Zhu Li-Ping; Qiu Yu; Tong Guo-Ping
2012-01-01
We numerically investigate the injection process of electrons from metal electrodes to one-dimensional organic molecules by combining the extended Su—Schrieffer—Heeger (SSH) model with a nonadiabatic dynamics method. It is found that a match between the Fermi level of electrodes and the highest occupied molecular orbital (HOMO) or the lowest unoccupied molecular orbital (LUMO) of organic molecules can be greatly affected by the length of the organic chains, which has a great impact on electron injection. The correlation between oligomers and electrodes is found to open more efficient channels for electron injection as compared with that in polymer/electrode structures. For oligomer/electrode structures, we show that the Schottky barrier essentially does not affect the electron injection as the electrode work function is smaller than a critical value. This means that the Schottky barrier is pinned for a small work-function electrode. For polymer/electrode structures, we find that it is possible for the Fermi level of electrodes to be pinned to the polaronic level. The condition under which the Fermi level of electrodes exceeds the polaronic level of polymers is shown to not always lead to spontaneous electron transfer from electrodes to polymers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Strong toroidal effects on tokamak tearing mode stability in the hybrid and conventional scenarios
International Nuclear Information System (INIS)
Ham, C J; Connor, J W; Cowley, S C; Gimblett, C G; Hastie, R J; Hender, T C; Martin, T J
2012-01-01
The hybrid scenario is thought to be an important mode of operation for the ITER tokamak. Analytic and numerical calculations demonstrate that toroidal effects at finite β have a strong influence on tearing mode stability of hybrid modes. Indeed, they persist in the large aspect ratio limit, R/a → ∞. A similar strong coupling effect is found between the m = 1, n = 1 harmonic and the m = 2, n = 1 harmonic if the minimum safety factor is less than unity. In both cases the tearing stability index, Δ′ increases rapidly as β approaches ideal marginal stability, providing a potential explanation for the onset of linearly unstable tearing modes. The numerical calculations have used an improved version of the T7 code (Fitzpatrick et al 1993 Nucl. Fusion 33 1533), and complete agreement is obtained with the analytic theory for this demanding test of the code. (paper)
Graphene nanomesh-based devices exhibiting a strong negative differential conductance effect
International Nuclear Information System (INIS)
Hung Nguyen, V; Mazzamuto, F; Saint-Martin, J; Bournel, A; Dollfus, P
2012-01-01
Using atomistic quantum simulation based on a tight binding model, we have investigated the transport characteristics of graphene nanomesh-based devices and evaluated the possibilities of observing negative differential conductance. It is shown that by taking advantage of bandgap opening in the graphene nanomesh lattice, a strong negative differential conductance effect can be achieved at room temperature in pn junctions and n-doped structures. Remarkably, the effect is improved very significantly (with a peak-to-valley current ratio of a few hundred) and appears to be weakly sensitive to the transition length in graphene nanomesh pn hetero-junctions when inserting a pristine (gapless) graphene section in the transition region between n and p zones. The study therefore suggests new design strategies for graphene electronic devices which may offer strong advantages in terms of performance and processing over the devices studied previously. (paper)
Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf
2015-05-07
We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to
International Nuclear Information System (INIS)
Harada, Masayasu; Kikukawa, Yoshio; Yamawaki, Koichi
2003-01-01
This issue presents the important recent progress in both theoretical and phenomenological issues of strong coupling gauge theories, with/without supersymmetry and extra dimensions, etc. Emphasis in a placed on dynamical symmetry breaking with large anomalous dimensions governed by the dynamics near the nontrivial fixed point. Also presented are recent developments of the corresponding effective field theories. The 43 of the presented papers are indexed individually. (J.P.N)
Generalized Models from Beta(p, 2) Densities with Strong Allee Effect: Dynamical Approach
Aleixo, Sandra M.; Rocha, J. Leonel
2012-01-01
A dynamical approach to study the behaviour of generalized populational growth models from Beta(p, 2) densities, with strong Allee effect, is presented. The dynamical analysis of the respective unimodal maps is performed using symbolic dynamics techniques. The complexity of the correspondent discrete dynamical systems is measured in terms of topological entropy. Different populational dynamics regimes are obtained when the intrinsic growth rates are modified: extinction, bistability, chaotic ...
Effect of an improved molecular potential on strong-field tunneling ionization of molecules
International Nuclear Information System (INIS)
Zhao Songfeng; Jin Cheng; Le, Anh-Thu; Lin, C. D.
2010-01-01
We study the effect of one-electron model potentials on the tunneling ionization rates of molecules in strong fields. By including electron correlation using the modified Leeuwen-Baerends (LB α) model, the binding energies of outer shells of molecules are significantly improved. However, we show that the tunneling ionization rates from the LB α do not differ much from the earlier calculations [Phys. Rev. A 81, 033423 (2010)], in which the local correlation potential was neglected.
Empty creditors and strong shareholders: The real effects of credit risk trading. Second draft
Colonnello, Stefano; Efing, Matthias; Zucchi, Francesca
2016-01-01
Credit derivatives give creditors the possibility to transfer debt cash flow rights to other market participants while retaining control rights. We use the market for credit default swaps (CDSs) as a laboratory to show that the real effects of such debt unbundling crucially hinge on shareholder bargaining power. We find that creditors buy more CDS protection when facing strong shareholders to secure themselves a valuable outside option in distressed renegotiations. After the start of CDS trad...
Poppers, Kaposi's sarcoma, and HIV infection: empirical example of a strong confounding effect?
Morabia, A
1995-01-01
Are there empirical examples of strong confounding effects? Textbooks usually show examples of weak confounding or use hypothetical examples of strong confounding to illustrate the paradoxical consequences of not separating out the effect of the studied exposure from that of second factor acting as a confounder. HIV infection is a candidate strong confounder of the spuriously high association reported between consumption of poppers, a sexual stimulant, and risk of Kaposi's sarcoma in the early phase of the AIDS epidemic. To examine this hypothesis, assumptions must be made on the prevalence of HIV infection among cases of Kaposi's sarcoma and on the prevalence of heavy popper consumption according to HIV infection in cases and controls. Results show that HIV infection may have confounded the poppers-Kaposi's sarcoma association. However, it cannot be ruled out that HIV did not qualify as a confounder because it was either an intermediate variable or an effect modifier of the association between popper inhalation and Kaposi's sarcoma. This example provides a basis to discuss the mechanism by which confounding occurs as well as the practical importance of confounding in epidemiologic research.
Jan, Luka; Fefer, Dušan; Košmelj, Katarina; Gaberščik, Alenka; Jerman, Igor
2015-04-01
The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants. © 2015 Wiley Periodicals, Inc.
On Drift Effects in Velocity and Displacement of Greek Uncorrected Digital Strong Motion Data
Skarlatoudis, A.; Margaris, B.
2005-12-01
Fifty years after the first installation of analog accelerographs, digital instruments recording the strong-motion came in operation. Their advantages comparing to the analog ones are obvious and they have been described in detail in several works. Nevertheless it has been pointed out that velocity and displacement values derived from several accelerograms, recorded in various strong earthquakes worldwide (e.g. 1999 Chi-Chi, Taiwan, Hector Mine, 2002 Denali) by digital instruments, are plagued by drifts when only a simple baseline correction derived from the pre-event portion of the record is removed. In Greece a significant number of accelerographic networks and arrays have been deployed covering the whole area. Digital accelerographs now constitute a significant part of the National Strong Motion network of the country. Detailed analyses of the data processing of accelerograms recorded by digital instruments exhibited that the same drifts exist in the Greek strong motion database. In this work, a methodology proposed and described in various articles (Boore, 2001; 2003; 2005) for removing the aforementioned drifts of the accelerograms is applied. It is also attempted a careful look of the nature of the drifts for understanding the noise characteristics relative to the signal. The intrinsic behaviour of signal to noise ratio is crucial for the adequacy of baseline corrections applied on digital uncorrected accelerograms. Velocities and displacements of the uncorrected and corrected accelerograms are compared and the drift effects in the Fourier and response spectra are presented.
Strong field effects on binary systems in Einstein-aether theory
International Nuclear Information System (INIS)
Foster, Brendan Z.
2007-01-01
'Einstein-aether' theory is a generally covariant theory of gravity containing a dynamical preferred frame. This article continues an examination of effects on the motion of binary pulsar systems in this theory, by incorporating effects due to strong fields in the vicinity of neutron star pulsars. These effects are included through an effective approach, by treating the compact bodies as point particles with nonstandard, velocity dependent interactions parametrized by dimensionless sensitivities. Effective post-Newtonian equations of motion for the bodies and the radiation damping rate are determined. More work is needed to calculate values of the sensitivities for a given fluid source; therefore, precise constraints on the theory's coupling constants cannot yet be stated. It is shown, however, that strong field effects will be negligible given current observational uncertainties if the dimensionless couplings are less than roughly 0.1 and two conditions that match the PPN parameters to those of pure general relativity are imposed. In this case, weak field results suffice. There then exists a one-parameter family of Einstein-aether theories with 'small-enough' couplings that passes all current observational tests. No conclusion can be reached for larger couplings until the sensitivities for a given source can be calculated
Anisotropy of the magnetoviscous effect in a cobalt ferrofluid with strong interparticle interaction
Energy Technology Data Exchange (ETDEWEB)
Linke, J.M., E-mail: julia.linke@tu-dresden.de; Odenbach, S.
2015-12-15
The anisotropy of the magnetoviscous effect (MVE) of a cobalt ferrofluid has been studied in a slit die viscometer for three orientations of the applied magnetic field: in the direction of the fluid flow (Δη{sub 1}), the velocity gradient (Δη{sub 2}), and the vorticity (Δη{sub 3}). The majority of the cobalt particles in the ferrofluid exhibit a strong dipole–dipole interaction, which corresponds to a weighted interaction parameter of λ{sub w}≈10.6. Thus the particles form extended microstructures inside the fluid which lead to enhanced MVE ratios Δη{sub 2}/Δη{sub 1}>3 and Δη{sub 3}/Δη{sub 1}>0.3 even for strong shearing and weak magnetic fields compared to fluids which contain non-interacting spherical particles with Δη{sub 2}/Δη{sub 1}≈1 and Δη{sub 3}/Δη{sub 1}=0. Furthermore, a non-monotonic increase has been observed in the shear thinning behavior of Δη{sub 2} for weak magnetic fields <10 kA/m, which cannot be explained solely by the magnetization of individual particles and the formation and disintegration of linear particle chains but indicates the presence of heterophase structures. - Highlights: • The magnetoviscous effect in a ferrofluid with strong interaction is anisotropic. • The strongest effects are found in a magnetic field parallel to the shear gradient. • In strong magnetic fields the microstructure of the fluid is stable against shearing. • In weak fields the fluid behavior indicates the presence of heterophase structures.
Strong Stability Preserving Explicit Runge--Kutta Methods of Maximal Effective Order
Hadjimichael, Yiannis
2013-07-23
We apply the concept of effective order to strong stability preserving (SSP) explicit Runge--Kutta methods. Relative to classical Runge--Kutta methods, methods with an effective order of accuracy are designed to satisfy a relaxed set of order conditions but yield higher order accuracy when composed with special starting and stopping methods. We show that this allows the construction of four-stage SSP methods with effective order four (such methods cannot have classical order four). However, we also prove that effective order five methods---like classical order five methods---require the use of nonpositive weights and so cannot be SSP. By numerical optimization, we construct explicit SSP Runge--Kutta methods up to effective order four and establish the optimality of many of them. Numerical experiments demonstrate the validity of these methods in practice.
Quantum screening effects on the ion-ion collisions in strongly coupled semiclassical plasmas
International Nuclear Information System (INIS)
Ki, Dae-Han; Jung, Young-Dae
2010-01-01
The quantum screening effects on the ion-ion collisions are investigated in strongly coupled semiclassical hydrogen plasmas. The method of stationary phase and effective interaction potential containing the quantum mechanical effect are employed to obtain the scattering phase shift and scattering cross section as functions of the impact parameter, collision energy, de Broglie wavelength, and Debye length. The result shows that the scattering phase and cross section decrease with increasing de Broglie wavelength. It is also shown that the scattering cross section increases with an increase of the Debye length. Hence, it is found that the quantum effect suppresses the scattering cross section. In addition, the quantum effect on the scattering cross section is found to be more important in small Debye length domains.
Strong Stability Preserving Explicit Runge--Kutta Methods of Maximal Effective Order
Hadjimichael, Yiannis; Macdonald, Colin B.; Ketcheson, David I.; Verner, James H.
2013-01-01
We apply the concept of effective order to strong stability preserving (SSP) explicit Runge--Kutta methods. Relative to classical Runge--Kutta methods, methods with an effective order of accuracy are designed to satisfy a relaxed set of order conditions but yield higher order accuracy when composed with special starting and stopping methods. We show that this allows the construction of four-stage SSP methods with effective order four (such methods cannot have classical order four). However, we also prove that effective order five methods---like classical order five methods---require the use of nonpositive weights and so cannot be SSP. By numerical optimization, we construct explicit SSP Runge--Kutta methods up to effective order four and establish the optimality of many of them. Numerical experiments demonstrate the validity of these methods in practice.
Three-loop Standard Model effective potential at leading order in strong and top Yukawa couplings
Energy Technology Data Exchange (ETDEWEB)
Martin, Stephen P. [Santa Barbara, KITP
2014-01-08
I find the three-loop contribution to the effective potential for the Standard Model Higgs field, in the approximation that the strong and top Yukawa couplings are large compared to all other couplings, using dimensional regularization with modified minimal subtraction. Checks follow from gauge invariance and renormalization group invariance. I also briefly comment on the special problems posed by Goldstone boson contributions to the effective potential, and on the numerical impact of the result on the relations between the Higgs vacuum expectation value, mass, and self-interaction coupling.
Polarization effects in above-threshold ionization with a mid-infrared strong laser field
Kang, Hui-Peng; Xu, Song-Po; Wang, Yan-Lan; Yu, Shao-Gang; Zhao, Xiao-Yun; Hao, Xiao-Lei; Lai, Xuan-Yang; Pfeifer, Thomas; Liu, Xiao-Jun; Chen, Jing; Cheng, Ya; Xu, Zhi-Zhan
2018-05-01
Using a semiclassical approach, we theoretically study the above-threshold ionization of magnesium by intense, mid-infrared laser pulses. The formation of low-energy structures in the photoelectron spectrum is found to be enhanced by comparing with a calculation based on the single-active electron approximation. By performing electron trajectory and recollision-time distribution analysis, we demonstrate that this phenomenon is due to the laser-induced ionic core polarization effects on the recolliding electrons. We also show that the polarization effects should be experimentally detectable. Our finding provides new insight into ultrafast control of strong-field photoionization and imaging of polar molecules.
Using strong nonlinearity and high-frequency vibrations to control effective mechanical stiffness
DEFF Research Database (Denmark)
Thomsen, Jon Juel
2008-01-01
the method of direct separation of motions with results of a modified multiple scales ap-proach, valid also for strong nonlinearity, the stiffening ef-fect is predicted for a generic 1-dof system, and results are tested against numerical simulation and ((it is planned)) laboratory experiments.......High-frequency excitation (HFE) can be used to change the effective stiffness of an elastic structure, and related quanti-ties such as resonance frequencies, wave speed, buckling loads, and equilibrium states. There are basically two ways to do this: By using parametrical HFE (with or without non...
Energy Technology Data Exchange (ETDEWEB)
Xie, Changjian [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Zhu, Xiaolei; Yarkony, David R., E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Ma, Jianyi, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610065 (China); Xie, Daiqian, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hua, E-mail: jianyi.m@gmail.com, E-mail: yarkony@jhu.edu, E-mail: dqxie@nju.edu.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
2015-03-07
Non-adiabatic processes play an important role in photochemistry, but the mechanism for conversion of electronic energy to chemical energy is still poorly understood. To explore the possibility of vibrational control of non-adiabatic dynamics in a prototypical photoreaction, namely, the A-band photodissociation of NH{sub 3}(X{sup ~1}A{sub 1}), full-dimensional state-to-state quantum dynamics of symmetric or antisymmetric stretch excited NH{sub 3}(X{sup ~1}A{sub 1}) is investigated on recently developed coupled diabatic potential energy surfaces. The experimentally observed H atom kinetic energy distributions are reproduced. However, contrary to previous inferences, the NH{sub 2}(A{sup ~2}A{sub 1})/NH{sub 2}(X{sup ~2}B{sub 1}) branching ratio is found to be small regardless of the initial preparation of NH{sub 3}(X{sup ~1}A{sub 1}), while the internal state distribution of the preeminent fragment, NH{sub 2}(X{sup ~2}B{sub 1}), is found to depend strongly on the initial vibrational excitation of NH{sub 3}(X{sup ~1}A{sub 1}). The slow H atoms in photodissociation mediated by the antisymmetric stretch fundamental state are due to energy sequestered in the internally excited NH{sub 2}(X{sup ~2}B{sub 1}) fragment, rather than in NH{sub 2}(A{sup ~2}A{sub 1}) as previously proposed. The high internal excitation of the NH{sub 2}(X{sup ~2}B{sub 1}) fragment is attributed to the torques exerted on the molecule as it passes through the conical intersection seam to the ground electronic state of NH{sub 3}. Thus in this system, contrary to previous assertions, the control of electronic state branching by selective excitation of ground state vibrational modes is concluded to be ineffective. The juxtaposition of precise quantum mechanical results with complementary results based on quasi-classical surface hopping trajectories provides significant insights into the non-adiabatic process.
Charging-delay effect on longitudinal dust acoustic shock wave in strongly coupled dusty plasma
International Nuclear Information System (INIS)
Ghosh, Samiran; Gupta, M.R.
2005-01-01
Taking into account the charging-delay effect, the nonlinear propagation characteristics of longitudinal dust acoustic wave in strongly coupled collisional dusty plasma described by generalized hydrodynamic model have been investigated. In the 'hydrodynamic limit', a Korteweg-de Vries Burger (KdVB) equation with a damping term arising due to dust-neutral collision is derived in which the Burger term is proportional to the dissipation due to dust viscosity through dust-dust correlation and charging-delay-induced anomalous dissipation. On the other hand, in the 'kinetic limit', a KdVB equation with a damping term and a nonlocal nonlinear forcing term arising due to memory-dependent strong correlation effect of dust fluid is derived in which the Burger term depends only on the charging-delay-induced dissipation. Numerical solution of integrodifferential equations reveals that (i) dissipation due to dust viscosity and principally due to charging delay causes excitation of the longitudinal dust acoustic shock wave in strongly coupled dusty plasma and (ii) dust-neutral collision does not appear to play any direct role in shock formation. The condition for the generation of shock is also discussed briefly
Strong coupling effects between a meta-atom and MIM nanocavity
Directory of Open Access Journals (Sweden)
San Chen
2012-09-01
Full Text Available In this paper, we investigate the strong coupling effects between a meta-atom and a metal-insulator-metal (MIM nanocavity. By changing the meta-atom sizes, we achieve the meta-atomic electric dipole, quadrupole or multipole interaction with the plasmonic nanocavity, in which characteristic anticrossing behaviors demonstrate the occurrence of the strong coupling. The various interactions present obviously different splitting values and behaviors of dependence on the meta-atomic position. The largest Rabi-type splittings, about 360.0 meV and 306.1 meV, have been obtained for electric dipole and quadrupole interaction, respectively. We attribute the large splitting to the highly-confined cavity mode and the large transition dipole of the meta-atom. Also the Rabi-type oscillation in time domain is given.
The effect of strong intermolecular and chemical interactions on the compatibility of polymers
International Nuclear Information System (INIS)
Askadskii, Andrei A
1999-01-01
The data on compatibility and on the properties of polymer blends are generalised. The emphasis is placed on the formation of strong intermolecular interactions (dipole-dipole interaction and hydrogen bonding) between the components of blends, as well as on the chemical reactions between them. A criterion for the prediction of compatibility of polymers is described in detail. Different cases of compatibility are considered and the dependences of the glass transition temperatures on the composition of blends are analysed. The published data on the effect of strong intermolecular interactions between the blend components on the glass transition temperature are considered. The preparation of interpolymers is described whose macromolecules are composed of incompatible polymers, which leads to the so-called 'forced compatibility.' The bibliography includes 80 references.
Three-dimensional photodissociation in strong laser fields: Memory-kernel effective-mode expansion
International Nuclear Information System (INIS)
Li Xuan; Thanopulos, Ioannis; Shapiro, Moshe
2011-01-01
We introduce a method for the efficient computation of non-Markovian quantum dynamics for strong (and time-dependent) system-bath interactions. The past history of the system dynamics is incorporated by expanding the memory kernel in exponential functions thereby transforming in an exact fashion the non-Markovian integrodifferential equations into a (larger) set of ''effective modes'' differential equations (EMDE). We have devised a method which easily diagonalizes the EMDE, thereby allowing for the efficient construction of an adiabatic basis and the fast propagation of the EMDE in time. We have applied this method to three-dimensional photodissociation of the H 2 + molecule by strong laser fields. Our calculations properly include resonance-Raman scattering via the continuum, resulting in extensive rotational and vibrational excitations. The calculated final kinetic and angular distribution of the photofragments are in overall excellent agreement with experiments, both when transform-limited pulses and when chirped pulses are used.
Small Fermi surfaces and strong correlation effects in Dirac materials with holography
Seo, Yunseok; Song, Geunho; Park, Chanyong; Sin, Sang-Jin
2017-10-01
Recent discovery of transport anomaly in graphene demonstrated that a system known to be weakly interacting may become strongly correlated if system parameter (s) can be tuned such that fermi surface is sufficiently small. We study the strong correlation effects in the transport coefficients of Dirac materials doped with magnetic impurity under the magnetic field using holographic method. The experimental data of magneto-conductivity are well fit by our theory, however, not much data are available for other transports of Dirac material in such regime. Therefore, our results on heat transport, thermo-electric power and Nernst coefficients are left as predictions of holographic theory for generic Dirac materials in the vicinity of charge neutral point with possible surface gap. We give detailed look over each magneto-transport observable and 3Dplots to guide future experiments.
arXiv Strong reduction of the effective radiation length in an oriented PWO scintillator crystal
Bandiera, L.; Romagnoni, M.; Argiolas, N.; Bagli, E.; Ballerini, G.; Berra, A.; Brizzolani, C.; Camattari, R.; De Salvador, D.; Haurylavets, V.; Mascagna, V.; Mazzolari, A.; Prest, M.; Soldani, M.; Sytov, A.; Vallazza, E.
We measured a considerable increase of the emitted radiation by 120 GeV/c electrons in an axially oriented lead tungstate scintillator crystal, if compared to the case in which the sample was not aligned with the beam direction. This enhancement resulted from the interaction of particles with the strong crystalline electromagnetic field. The data collected at the external lines of CERN SPS were critically compared to Monte Carlo simulations based on the Baier Katkov quasiclassical method, highlighting a reduction of the scintillator radiation length by a factor of five in case of beam alignment with the [001] crystal axes. The observed effect opens the way to the realization of compact electromagnetic calorimeters/detectors based on oriented scintillator crystals in which the amount of material can be strongly reduced with respect to the state of the art. These devices could have relevant applications in fixed-target experiments as well as in satellite-borne gamma-telescopes.
Strong Quantum Size Effects in Pb(111) Thin Films Mediated by Anomalous Friedel Oscillations
Jia, Yu; Wu, Biao; Li, Chong; Einstein, T. L.; Weitering, H. H.; Zhang, Zhenyu
2010-08-01
Using first-principles calculations within density functional theory, we study Friedel oscillations (FOs) in the electron density at different metal surfaces and their influence on the lattice relaxation and stability of ultrathin metal films. We show that the FOs at the Pb(111) surface decay as 1/x with the distance x from the surface, different from the conventional 1/x2 power law at other metal surfaces. The underlying physical reason for this striking difference is tied to the strong nesting of the two different Fermi sheets along the Pb(111) direction. The interference of the strong FOs emanating from the two surfaces of a Pb(111) film, in turn, not only results in superoscillatory interlayer relaxations around the center of the film, but also determines its stability in the quantum regime. As a simple and generic picture, the present findings also explain why quantum size effects are exceptionally robust in Pb(111) films.
Effective action for superfluid Fermi systems in the strong-coupling limit
International Nuclear Information System (INIS)
Dupuis, N.
2005-01-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρ r and its conjugate variable, the phase θ r of the pairing order parameter Δ r . We recover the standard action of a Bose superfluid of density ρ r /2, where the bosons have a mass m B =2m and interact via a repulsive contact potential with amplitude g B =4πa B /m B ,a B =2a (a the s-wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude t B =J/2 and an on-site repulsive interaction U B =2Jz, where J=4t 2 /U (t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites)
Effective action for superfluid Fermi systems in the strong-coupling limit
Dupuis, N.
2005-07-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρr and its conjugate variable, the phase θr of the pairing order parameter Δr . We recover the standard action of a Bose superfluid of density ρr/2 , where the bosons have a mass mB=2m and interact via a repulsive contact potential with amplitude gB=4πaB/mB,aB=2a ( a the s -wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude tB=J/2 and an on-site repulsive interaction UB=2Jz , where J=4t2/U ( t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites).
The quantum dynamics of electronically nonadiabatic chemical reactions
Truhlar, Donald G.
1993-01-01
Considerable progress was achieved on the quantum mechanical treatment of electronically nonadiabatic collisions involving energy transfer and chemical reaction in the collision of an electronically excited atom with a molecule. In the first step, a new diabatic representation for the coupled potential energy surfaces was created. A two-state diabatic representation was developed which was designed to realistically reproduce the two lowest adiabatic states of the valence bond model and also to have the following three desirable features: (1) it is more economical to evaluate; (2) it is more portable; and (3) all spline fits are replaced by analytic functions. The new representation consists of a set of two coupled diabatic potential energy surfaces plus a coupling surface. It is suitable for dynamics calculations on both the electronic quenching and reaction processes in collisions of Na(3p2p) with H2. The new two-state representation was obtained by a three-step process from a modified eight-state diatomics-in-molecules (DIM) representation of Blais. The second step required the development of new dynamical methods. A formalism was developed for treating reactions with very general basis functions including electronically excited states. Our formalism is based on the generalized Newton, scattered wave, and outgoing wave variational principles that were used previously for reactive collisions on a single potential energy surface, and it incorporates three new features: (1) the basis functions include electronic degrees of freedom, as required to treat reactions involving electronic excitation and two or more coupled potential energy surfaces; (2) the primitive electronic basis is assumed to be diabatic, and it is not assumed that it diagonalizes the electronic Hamiltonian even asymptotically; and (3) contracted basis functions for vibrational-rotational-orbital degrees of freedom are included in a very general way, similar to previous prescriptions for locally
Matching-pursuit/split-operator Fourier-transform simulations of nonadiabatic quantum dynamics
Wu, Yinghua; Herman, Michael F.; Batista, Victor S.
2005-03-01
A rigorous and practical approach for simulations of nonadiabatic quantum dynamics is introduced. The algorithm involves a natural extension of the matching-pursuit/split-operator Fourier-transform (MP/SOFT) method [Y. Wu and V. S. Batista, J. Chem. Phys. 121, 1676 (2004)] recently developed for simulations of adiabatic quantum dynamics in multidimensional systems. The MP/SOFT propagation scheme, extended to nonadiabatic dynamics, recursively applies the time-evolution operator as defined by the standard perturbation expansion to first-, or second-order, accuracy. The expansion is implemented in dynamically adaptive coherent-state representations, generated by an approach that combines the matching-pursuit algorithm with a gradient-based optimization method. The accuracy and efficiency of the resulting propagation method are demonstrated as applied to the canonical model systems introduced by Tully for testing simulations of dual curve-crossing nonadiabatic dynamics.
International Nuclear Information System (INIS)
Kondorskiy, A.; Nakamura, H.
2004-01-01
The title theory is developed by combining the Herman-Kluk semiclassical theory for adiabatic propagation on single potential-energy surface and the semiclassical Zhu-Nakamura theory for nonadiabatic transition. The formulation with use of natural mathematical principles leads to a quite simple expression for the propagator based on classical trajectories and simple formulas are derived for overall adiabatic and nonadiabatic processes. The theory is applied to electronically nonadiabatic photodissociation processes: a one-dimensional problem of H 2 + in a cw (continuous wave) laser field and a two-dimensional model problem of H 2 O in a cw laser field. The theory is found to work well for the propagation duration of several molecular vibrational periods and wide energy range. Although the formulation is made for the case of laser induced nonadiabatic processes, it is straightforwardly applicable to ordinary electronically nonadiabatic chemical dynamics
Poly-ϵ-caprolactone/chitosan nanoparticles provide strong adjuvant effect for hepatitis B antigen.
Jesus, Sandra; Soares, Edna; Borchard, Gerrit; Borges, Olga
2017-10-01
This work aims to investigate the adjuvant effect of poly-ϵ-caprolactone/chitosan nanoparticles (NPs) for hepatitis B surface antigen (HBsAg) and the plasmid DNA encoding HBsAg (pRC/CMV-HBs). Both antigens were adsorbed onto preformed NPs. Vaccination studies were performed in C57BL/6 mice. Transfection efficiency was investigated in A549 cell line. HBsAg-adsorbed NPs generated strong anti-HBsAg IgG titers, mainly of IgG1 isotype, and induced antigen-specific IFN-γ and IL-17 secretion by spleen cells. The addition of pRC/CMV-HBs to the HBsAg-adsorbed NPs inhibited IL-17 secretion but had minor effect on IFN-γ levels. Lastly, pRC/CMV-HBs-loaded NPs generated a weak serum antibody response. Poly-ϵ-caprolactone/chitosan NPs provide a strong humoral adjuvant effect for HBsAg and induce a Th1/Th17-mediated cellular immune responses worth explore for hepatitis B virus vaccination.
Effects of copper ions on the characteristics of egg white gel induced by strong alkali.
Shao, Yaoyao; Zhao, Yan; Xu, Mingsheng; Chen, Zhangyi; Wang, Shuzhen; Tu, Yonggang
2017-09-01
This study investigated the effects of copper ions on egg white (EW) gel induced by strong alkali. Changes in gel characteristics were examined through texture profile analysis, scanning electron microscopy (SEM), and chemical methods. The value of gel strength reached its maximum when 0.1% copper ions was added. However, the lowest cohesiveness values were observed at 0.1%. The springiness of gel without copper ions was significantly greater than the gel with copper ions added. SEM results illustrated that the low concentration of copper ions contributes to a dense and uniform gel network, and an open matrix was formed at 0.4%. The free and total sulphhydryl group content in the egg white protein gel significantly decreased with the increased copper. The increase of copper ions left the contents of ionic and hydrogen bonds basically unchanged, hydrophobic interaction presented an increasing trend, and the disulfide bond exhibited a completely opposite change. The change of surface hydrophobicity proved that the main binding force of copper induced gel was hydrophobic interaction. However, copper ions had no effect on the protein component of the gels. Generally, a low level of copper ions facilitates protein-protein association, which is involved in the characteristics of gels. Instead, high ionic strength had a negative effect on gels induced by strong alkali. © 2017 Poultry Science Association Inc.
Effect of Dislocation Density on Deformation Behavior of Super Strong Bainitic Steel
Directory of Open Access Journals (Sweden)
B. Avishan
2017-02-01
Full Text Available Presence of nanoscale bainitic ferrites and high carbon retained austenites that are stable at ambient temperature within the microstructures of super strong bainitic steels makes it possible to achieve exceptional strengths and ductility properties in these groups of nanostructured steels. This article aims to study the effect of the dislocation density variations during tensile testing in ambient temperature on deformation behavior of nanostructured low temperature bainitic steels. Results indicate that dislocation absorption from bainitic ferrite subunits by surrounding retained austenite reduces the work hardening and therefore increases the formability of bainitic ferrite during deformation, which in turn results in a suitable combination of strength and ductility.
Dispersion of Co/CNTs via strong electrostatic adsorption method: Thermal treatment effect
Energy Technology Data Exchange (ETDEWEB)
Akbarzadeh, Omid, E-mail: omid.akbarzadeh63@gmail.com; Abdullah, Bawadi, E-mail: bawadi-abdullah@petronas.com.my; Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Zabidi, Noor Asmawati Mohd, E-mail: noorasmawati-mzabidi@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)
2015-07-22
The effect of different thermal treatment temperature on the structure of multi-walled carbon nanotubes (MWCNTs) and Co particle dispersion on CNTs support is studied using Strong electrostatic adsorption (SEA) method. The samples tested by N{sub 2}-adsorption, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). N{sub 2}-adsorption results showed BET surface area increased using thermal treatment and TEM images showed that increasing the thermal treatment temperature lead to flaky CNTs and defects introduced on the outer surface and Co particle dispersion increased.
Orrock, John L; Dutra, Humberto P; Marquis, Robert J; Barber, Nicholas
2015-04-01
Direct and indirect effects can play a key role in invasions, but experiments evaluating both are rare. We examined the roles of direct competition and apparent competition by exotic Amur honeysuckle (Lonicera maackii) by manipulating (1) L. maackii vegetation, (2) presence of L. maackii fruits, and (3) access to plants by small mammals and deer. Direct competition with L. maackii reduced the abundance and richness of native and exotic species, and native consumers significantly reduced the abundance and richness of native species. Although effects of direct competition and consumption were more pervasive, richness of native plants was also reduced through apparent competition, as small-mammal consumers reduced richness only when L. maackii fruits were present. Our experiment reveals the multiple, interactive pathways that affect the success and impact of an invasive exotic plant: exotic plants may directly benefit from reduced attack by native consumers, may directly exert strong competitive effects on native plants, and may also benefit from apparent competition.
Non-adiabatic quantum state preparation and quantum state transport in chains of Rydberg atoms
Ostmann, Maike; Minář, Jiří; Marcuzzi, Matteo; Levi, Emanuele; Lesanovsky, Igor
2017-12-01
Motivated by recent progress in the experimental manipulation of cold atoms in optical lattices, we study three different protocols for non-adiabatic quantum state preparation and state transport in chains of Rydberg atoms. The protocols we discuss are based on the blockade mechanism between atoms which, when excited to a Rydberg state, interact through a van der Waals potential, and rely on single-site addressing. Specifically, we discuss protocols for efficient creation of an antiferromagnetic GHZ state, a class of matrix product states including a so-called Rydberg crystal and for the state transport of a single-qubit quantum state between two ends of a chain of atoms. We identify system parameters allowing for the operation of the protocols on timescales shorter than the lifetime of the Rydberg states while yielding high fidelity output states. We discuss the effect of positional disorder on the resulting states and comment on limitations due to other sources of noise such as radiative decay of the Rydberg states. The proposed protocols provide a testbed for benchmarking the performance of quantum information processing platforms based on Rydberg atoms.
International Nuclear Information System (INIS)
Hatcher, Elizabeth; Soudackov, Alexander; Hammes-Schiffer, Sharon
2005-01-01
The dynamical aspects of a model proton-coupled electron transfer (PCET) reaction in solution are analyzed with molecular dynamics simulations. The rate for nonadiabatic PCET is expressed in terms of a time-dependent probability flux correlation function. The impact of the proton donor-acceptor and solvent dynamics on the probability flux is examined. The dynamical behavior of the probability flux correlation function is dominated by a solvent damping term that depends on the energy gap correlation function. The proton donor-acceptor motion does not impact the dynamical behavior of the probability flux correlation function but does influence the magnitude of the rate. The approximations previously invoked for the calculation of PCET rates are tested. The effects of solvent damping on the proton donor-acceptor vibrational motion are found to be negligible, and the short-time solvent approximation, in which only equilibrium fluctuations of the solvent are considered, is determined to be valid for these types of reactions. The analysis of PCET reactions is compared to previous analyses of single electron and proton transfer reactions. The dynamical behavior is qualitatively similar for all three types of reactions, but the time scale of the decay of the probability flux correlation function is significantly longer for single proton transfer than for PCET and single electron transfer due to a smaller solvent reorganization energy for proton transfer
Nonadiabatic Dynamics for Electrons at Second-Order: Real-Time TDDFT and OSCF2.
Nguyen, Triet S; Parkhill, John
2015-07-14
We develop a new model to simulate nonradiative relaxation and dephasing by combining real-time Hartree-Fock and density functional theory (DFT) with our recent open-systems theory of electronic dynamics. The approach has some key advantages: it has been systematically derived and properly relaxes noninteracting electrons to a Fermi-Dirac distribution. This paper combines the new dissipation theory with an atomistic, all-electron quantum chemistry code and an atom-centered model of the thermal environment. The environment is represented nonempirically and is dependent on molecular structure in a nonlocal way. A production quality, O(N(3)) closed-shell implementation of our theory applicable to realistic molecular systems is presented, including timing information. This scaling implies that the added cost of our nonadiabatic relaxation model, time-dependent open self-consistent field at second order (OSCF2), is computationally inexpensive, relative to adiabatic propagation of real-time time-dependent Hartree-Fock (TDHF) or time-dependent density functional theory (TDDFT). Details of the implementation and numerical algorithm, including factorization and efficiency, are discussed. We demonstrate that OSCF2 approaches the stationary self-consistent field (SCF) ground state when the gap is large relative to k(b)T. The code is used to calculate linear-response spectra including the effects of bath dynamics. Finally, we show how our theory of finite-temperature relaxation can be used to correct ground-state DFT calculations.
Nonadiabatic production of spinor condensates with a quadrupole-Ioffe-configuration trap
International Nuclear Information System (INIS)
Zhang, P.; Xu, Z.; You, L.
2006-01-01
Motivated by the recent experimental observation of multicomponent spinor condensates via a time-dependent quadrupole-Ioffe-configuration trap, we provide a general framework for the investigation of nonadiabatic Landau-Zener dynamics of a hyperfine spin, e.g., from an atomic magnetic dipole moment coupled to a weak time-dependent magnetic (B-) field. The spin flipped population distribution, or the so-called Majorona formula, is expressed in terms of system parameters and experimental observables; thus, the distribution provides much needed insight into the underlying mechanism for the production of spinor condensates due to nonadiabatic level crossings
Quantum theory of nonadiabatic heavy-particle transfer processes in polar media
International Nuclear Information System (INIS)
Kuznetsov, A.M.
1986-01-01
For the probability of nonadiabatic transfer of heavy particles, a calculating procedure is proposed which in the case of certain processes allows the interaction between motion of the particle undergoing transfer and motion along other degrees of freedom to be exactly accounted for. In the case of symmetric systems, explicit expressions are obtained for the free energy of activation of the transition and for the tunneling factor which allow for nonadiabaticity of motion of the particle undergoing transfer, both in the region beneath the barrier and in the region that is classically accessible
STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS
International Nuclear Information System (INIS)
Wang Yan; Li Xiangdong
2012-01-01
If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.
Directory of Open Access Journals (Sweden)
Joy Kish
2014-10-01
Full Text Available The purpose of this study was to determine the characteristics and motivational factors of effective Extension advisory leaders. This Delphi study was conducted with a selected group of County Extension Directors and a group of Extension State Advisory Leaders. The study identified 10 characteristics that distinguish an effective Extension advisory leader. Some of these characteristics are explicit and easy to observe, while others are implicit and difficult to directly observe. Therefore, it is practical to use directly observable characteristics of effective advisory leaders when selecting volunteers. Once potential volunteers are spotted in the community, implicit characteristics of effective advisory leaders should be used to further screen them before they are selected. The study also identified the eight most important factors motivating individuals to volunteer as effective advisory leaders. Understanding these motivational factors is helpful for creating an environment for attracting and retaining effective volunteers. Understanding their motivation for volunteer work and creating an environment for them to meet the motivating factors for volunteering will lead to volunteer satisfaction and retention. The findings of this study can be used to build strong Extension advisory councils.
Trapped in the extinction vortex? Strong genetic effects in a declining vertebrate population
Directory of Open Access Journals (Sweden)
Larsson Mikael
2010-02-01
Full Text Available Abstract Background Inbreeding and loss of genetic diversity are expected to increase the extinction risk of small populations, but detailed tests in natural populations are scarce. We combine long-term population and fitness data with those from two types of molecular markers to examine the role of genetic effects in a declining metapopulation of southern dunlins Calidris alpina schinzii, an endangered shorebird. Results The decline is associated with increased pairings between related individuals, including close inbreeding (as revealed by both field observations of parentage and molecular markers. Furthermore, reduced genetic diversity seems to affect individual fitness at several life stages. Higher genetic similarity between mates correlates negatively with the pair's hatching success. Moreover, offspring produced by related parents are more homozygous and suffer from increased mortality during embryonic development and possibly also after hatching. Conclusions Our results demonstrate strong genetic effects in a rapidly declining population, emphasizing the importance of genetic factors for the persistence of small populations.
Strong strain rate effect on the plasticity of amorphous silica nanowires
International Nuclear Information System (INIS)
Yue, Yonghai; Zheng, Kun
2014-01-01
With electron-beam (e-beam) off, in-situ tensile experiments on amorphous silica nanowires (NWs) were performed inside a transmission electron microscope (TEM). By controlling the loading rates, the strain rate can be adjusted accurately in a wide range. The result shows a strong strain rate effect on the plasticity of amorphous silica NWs. At lower strain rate, the intrinsic brittle materials exhibit a pronounced elongation higher than 100% to failure with obvious necking near ambient temperature. At the strain rate higher than 5.23 × 10 −3 /s, the elongation of the NW decreased dramatically, and a brittle fracture feature behavior was revealed. This ductile feature of the amorphous silica NWs has been further confirmed with the in-situ experiments under optical microscopy while the effect of e-beam irradiation could be eliminated.
Energy Technology Data Exchange (ETDEWEB)
Shaginyan, V.R. [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)], E-mail: vrshag@thd.pnpi.spb.ru; Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)
2009-06-15
Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc., gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh{sub 2}Si{sub 2}.
International Nuclear Information System (INIS)
Shaginyan, V.R.; Amusia, M.Ya.; Popov, K.G.
2009-01-01
Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc., gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh 2 Si 2 .
Effect of linear chirp on strong field photodissociation of H+2
International Nuclear Information System (INIS)
Prabhudesai, Vaibhav; Natan, Adi; Bruner, Barry; Silberberg, Yaron; Lev, Uri; Heber, Oded; Strasser, Daniel; Schwalm, Dirk; Zajfman, Daniel; Ben-Itzhak, Itzik
2011-01-01
We report the experimental findings of a systematic study of the effect of linear chirp on strong field photodissociation of H + 2 . For vibrational levels around or above the one photon crossing, the effect manifests itself in terms of a shift in the kinetic energy release (KER) peaks. The peaks shift up for negative chirp whereas they shift down for positive chirp. The measurements are carried out by varying two of the three laser pulse characteristics, energy, pulse peak intensity and linear chirp, while keeping the third constant. The shifts in the KER peaks are found to be intensity dependent for a given value of chirp. However, in the last two cases (i.e., fixed pulsed energy and fixed pulse peak intensity), they are found to be independent of the chirp magnitude. The results are understood on the basis of saturation of photodissociation probabilities for these levels.
Effect of linear chirp on strong field photodissociation of H{sup +}{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Prabhudesai, Vaibhav; Natan, Adi; Bruner, Barry; Silberberg, Yaron; Lev, Uri; Heber, Oded; Strasser, Daniel; Schwalm, Dirk; Zajfman, Daniel [Weizmann Institute of Science, 76100 (Israel); Ben-Itzhak, Itzik [Kansas State University, Kansas (United States)
2011-10-15
We report the experimental findings of a systematic study of the effect of linear chirp on strong field photodissociation of H{sup +}{sub 2}. For vibrational levels around or above the one photon crossing, the effect manifests itself in terms of a shift in the kinetic energy release (KER) peaks. The peaks shift up for negative chirp whereas they shift down for positive chirp. The measurements are carried out by varying two of the three laser pulse characteristics, energy, pulse peak intensity and linear chirp, while keeping the third constant. The shifts in the KER peaks are found to be intensity dependent for a given value of chirp. However, in the last two cases (i.e., fixed pulsed energy and fixed pulse peak intensity), they are found to be independent of the chirp magnitude. The results are understood on the basis of saturation of photodissociation probabilities for these levels.
Long-term effects of the strong African American families program on youths' alcohol use.
Brody, Gene H; Chen, Yi-Fu; Kogan, Steven M; Murry, Velma McBride; Brown, Anita C
2010-04-01
This report extends earlier accounts by addressing the effects of the Strong African American Families (SAAF) program across 65 months. Two hypotheses were tested: (a) Rural African American youths randomly assigned to participate in SAAF would demonstrate lower rates of alcohol use than would control youths more than 5 years later, and (b) SAAF's effects on deterring the onset of alcohol use in early adolescence would carry forward to mediate the program's long-term effects. African American youths in rural Georgia (mean age at pretest = 10.8 years) were assigned randomly to the SAAF group (n = 369) or to a control group (n = 298). Past-month alcohol use was assessed at pretest and at 9, 18, 29, 53, and 65 months after pretest. SAAF participants increased their alcohol use at a slower rate than did adolescents in the control condition across the follow-up assessments. At the 65-month assessment, SAAF participants reported having drunk alcohol half as often as did youths in the control group. Consistent with the second hypothesis, SAAF's effects on deterring initiation carried forward to account for its effects on alcohol use across time. Training in protective parenting processes and self-regulatory skills during preadolescence may contribute to a self-sustaining trajectory of disinterest in and avoidance of alcohol use during adolescence when peers begin to model and sanction it. (c) 2010 APA, all rights reserved
Observations of nonadiabatic acceleration of ions in Earth's magnetotail
Frank, L. A.; Paterson, W. R.; Kivelson, M. G.
1994-01-01
We present observations of the three-dimensional velocity distributions of protons in the energy range 20 eV to 52 keV at locations within and near the current sheet of Earth's magnetotail at geocentric radial distances 35 to 87 R(sub E). These measurements were acquired on December 8, 1990, with a set of electrostatic analyzers on board the Galileo spacecraft during its approach to Earth in order to obtain one of its gravitational assists to Jupiter. It is found that the velocity distributions are inadequately described as quasi-Maxwellian distributions such as those found in the central plasma sheet at positions nearer to Earth. Instead the proton velocity distributions can be categorized into two major types. The first type is the 'lima bean' shaped distribution with high-speed bulk flows and high temperatures that are similar to those found nearer to Earth in the plasma sheet boundary layer. The second type consists of colder protons with considerably lesser bulk flow speeds. Examples of velocity distributions are given for the plasma mantle, a region near the magnetic neutral line, positions earthward and tailward of the neutral line, and the plasma sheet boundary layer. At positions near the neutral line, only complex velocity distributions consisting of the colder protons are found, whereas both of the above types of distributions are found in and near the current sheet at earthward and tailward locations. Bulk flows are directed generally earthward and tailward at positions earthward and tailward of the neutral line, respectively. Only the high-speed, hot distribution is present in the plasma sheet boundary layer. The observations are interpreted in terms of the nonadiabatic acceleration of protons that flow into the current sheet from the plasma mantle. For this interpretation the hot, 'lima bean' shaped distributions are associated with meandering, or Speiser, orbits in the current sheet. It is suggested that the colder, lower-speed proton velocity
Mental health care and average happiness: strong effect in developed nations.
Touburg, Giorgio; Veenhoven, Ruut
2015-07-01
Mental disorder is a main cause of unhappiness in modern society and investment in mental health care is therefore likely to add to average happiness. This prediction was checked in a comparison of 143 nations around 2005. Absolute investment in mental health care was measured using the per capita number of psychiatrists and psychologists working in mental health care. Relative investment was measured using the share of mental health care in the total health budget. Average happiness in nations was measured with responses to survey questions about life-satisfaction. Average happiness appeared to be higher in countries that invest more in mental health care, both absolutely and relative to investment in somatic medicine. A data split by level of development shows that this difference exists only among developed nations. Among these nations the link between mental health care and happiness is quite strong, both in an absolute sense and compared to other known societal determinants of happiness. The correlation between happiness and share of mental health care in the total health budget is twice as strong as the correlation between happiness and size of the health budget. A causal effect is likely, but cannot be proved in this cross-sectional analysis.
Effect of Floodplain Inundation on River Pollution in Taiwan's Strong Monsoonal Climate
Hester, E. T.; Lin, A. Y. C.
2017-12-01
River-floodplain interaction provides important benefits such as flood mitigation, provision of ecological habitat, and improved water quality. Human actions have historically reduced such interaction and associated benefits by diking, floodplain fill, and river regulation. In response, floodplain restoration has become popular in North America and Europe, but is less practiced in Asia. In Taiwan, unusually strong monsoons and steep terrain alter floodplain dynamics relative to elsewhere around the world, and provide a unique environment for floodplain management. We used numerical models of flow, transport, and reaction in river channels and floodplains to quantify the effect of river-floodplain interaction on water quality in Taiwan's strong monsoon and high topographic relief. We conducted sensitivity analyses of parameters such as river slope, monsoon severity, reservoir operation mode, degree of floodplain reconnection, contaminant reaction rate, and contaminant reaction type on floodplain connectivity and contaminant mitigation. We found significant differences in floodplain hydraulics and residence times in Taiwan's steep monsoonal environment relative to the shallower non-monsoonal environment typical of the eastern USA, with significant implications for water quality. For example, greater flashiness of floodplain inundation in Taiwan provides greater challenges for reconnecting sufficient floodplain volume to handle monsoonal runoff. Yet longer periods when floodplains are reliably dry means that such lands may have greater value for seasonal use such as parks or agriculture. The potential for floodplain restoration in Taiwan is thus significant, but qualitatively different than in the eastern USA.
First-principles study of strong correlation effects in pyrochlore iridates
Energy Technology Data Exchange (ETDEWEB)
Shinaoka, Hiroshi [Department of Physics, Saitama University (Japan); Hoshino, Shintaro [Department of Basic Science, The University of Tokyo (Japan); Troyer, Matthias [Theoretische Physik, ETH Zuerich (Switzerland); Werner, Philipp [Department of Physics, University of Fribourg (Switzerland)
2016-07-01
The pyrochlore iridates A{sub 2}Ir{sub 2}O{sub 7} (A=Pr, Nd, Y, etc.) are an ideal system to study fascinating phenomena induced by strong electron correlations and spin-orbit coupling. In this talk, we study strong correlation effects in the prototype compound Y{sub 2}Ir{sub 2}O{sub 7} using the local density approximation and dynamical mean-field theory (LDA+DMFT). We map out the phase diagram in the space of temperature, onsite Coulomb repulsion U, and filling. Consistent with experiments, we find that an all-in/all-out ordered insulating phase is stable for realistic values of U. We reveal the importance of the hybridization between j{sub eff} = 1/2 and j{sub eff} = 3/2 states under the Coulomb interaction and trigonal crystal field. We demonstrate a substantial band narrowing in the paramagnetic metallic phase and non-Fermi liquid behavior in the electron/hole doped system originating from long-lived quasi-spin moments induced by nearly flat bands. We further compare our results with recent experimental results of Eu{sub 2}Ir{sub 2}O{sub 7} under hydrostatic pressure.
Effect of parameter mismatch on the dynamics of strongly coupled self sustained oscillators.
Chakrabarty, Nilaj; Jain, Aditya; Lal, Nijil; Das Gupta, Kantimay; Parmananda, Punit
2017-01-01
In this paper, we present an experimental setup and an associated mathematical model to study the synchronization of two self-sustained, strongly coupled, mechanical oscillators (metronomes). The effects of a small detuning in the internal parameters, namely, damping and frequency, have been studied. Our experimental system is a pair of spring wound mechanical metronomes; coupled by placing them on a common base, free to move along a horizontal direction. We designed a photodiode array based non-contact, non-magnetic position detection system driven by a microcontroller to record the instantaneous angular displacement of each oscillator and the small linear displacement of the base, coupling the two. In our system, the mass of the oscillating pendula forms a significant fraction of the total mass of the system, leading to strong coupling of the oscillators. We modified the internal mechanism of the spring-wound "clockwork" slightly, such that the natural frequency and the internal damping could be independently tuned. Stable synchronized and anti-synchronized states were observed as the difference in the parameters was varied in the experiments. The simulation results showed a rapid increase in the phase difference between the two oscillators beyond a certain threshold of parameter mismatch. Our simple model of the escapement mechanism did not reproduce a complete 180° out of phase state. However, the numerical simulations show that increased mismatch in parameters leads to a synchronized state with a large phase difference.
Interferon-β gene transfer induces a strong cytotoxic bystander effect on melanoma cells.
Rossi, Úrsula A; Gil-Cardeza, María L; Villaverde, Marcela S; Finocchiaro, Liliana M E; Glikin, Gerardo C
2015-05-01
A local gene therapy scheme for the delivery of type I interferons could be an alternative for the treatment of melanoma. We evaluated the cytotoxic effects of interferon-β (IFNβ) gene lipofection on tumor cell lines derived from three human cutaneous and four canine mucosal melanomas. The cytotoxicity of human IFNβ gene lipofection resulted higher or equivalent to that of the corresponding addition of the recombinant protein (rhIFNβ) to human cells. IFNβ gene lipofection was not cytotoxic for only one canine melanoma cell line. When cultured as monolayers, three human and three canine IFNβ-lipofected melanoma cell lines displayed a remarkable bystander effect. As spheroids, the same six cell lines were sensitive to IFNβ gene transfer, two displaying a significant multicell resistance phenotype. The effects of conditioned IFNβ-lipofected canine melanoma cell culture media suggested the release of at least one soluble thermolabile cytotoxic factor that could not be detected in human melanoma cells. By using a secretion signal-free truncated human IFNβ, we showed that its intracellular expression was enough to induce cytotoxicity in two human melanoma cell lines. The lower cytoplasmatic levels of reactive oxygen species detected after intracellular IFNβ expression could be related to the resistance displayed by one human melanoma cell line. As IFNβ gene transfer was effective against most of the assayed melanomas in a way not limited by relatively low lipofection efficiencies, the clinical potential of this approach is strongly supported. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
Biodiversity effects in the wild are common and as strong as key drivers of productivity.
Duffy, J Emmett; Godwin, Casey M; Cardinale, Bradley J
2017-09-14
More than 500 controlled experiments have collectively suggested that biodiversity loss reduces ecosystem productivity and stability. Yet the importance of biodiversity in sustaining the world's ecosystems remains controversial, largely because of the lack of validation in nature, where strong abiotic forcing and complex interactions are assumed to swamp biodiversity effects. Here we test this assumption by analysing 133 estimates reported in 67 field studies that statistically separated the effects of biodiversity on biomass production from those of abiotic forcing. Contrary to the prevailing opinion of the previous two decades that biodiversity would have rare or weak effects in nature, we show that biomass production increases with species richness in a wide range of wild taxa and ecosystems. In fact, after controlling for environmental covariates, increases in biomass with biodiversity are stronger in nature than has previously been documented in experiments and comparable to or stronger than the effects of other well-known drivers of productivity, including climate and nutrient availability. These results are consistent with the collective experimental evidence that species richness increases community biomass production, and suggest that the role of biodiversity in maintaining productive ecosystems should figure prominently in global change science and policy.
Room temperature strong coupling effects from single ZnO nanowire microcavity
Das, Ayan
2012-05-01
Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non-linearity in the polariton emission characteristics is observed at room temperature with a low threshold of 1.63 ?J/cm2, which corresponds to a polariton density an order of magnitude smaller than that for the Mott transition. The momentum distribution of the lower polaritons shows evidence of dynamic condensation and the absence of a relaxation bottleneck. The polariton relaxation dynamics were investigated by timeresolved measurements, which showed a progressive decrease in the polariton relaxation time with increase in polariton density. © 2012 Optical Society of America.
Smagin, A. V.; Sadovnikova, N. B.; Smagina, M. V.
2014-06-01
The biodestruction of strongly swelling polymer hydrogels (water adsorbing soil conditioners of the new generation) has been studied at the quantitative level using original mathematical models. In laboratory experiments, a relationship between the hydrogel degradation rate and the temperature has been obtained, and the effect of the biodestruction on the water retention curve of soil compositions with hydrogels (used as an index of their water retention capacity) has been assessed. From the automatic monitoring data of the temperature regime of soils, the potential biodestruction of hydrogels has been predicted for different climatic conditions. The loss of hydrogels during three months of the vegetation period because of destruction can exceed 30% of their initial content in irrigated agriculture under arid climatic conditions and more than 10% under humid climatic conditions. Thus, the biodestruction of hydrogels is one of the most important factors decreasing their efficiency under actual soil conditions.
International Nuclear Information System (INIS)
Silverman, J.N.
1983-01-01
A generalized Euler transformation (GET) is introduced which provides a powerful alternative method of accurately summing strongly divergent Rayleigh-Schroedinger (RS) perturbation series when other summability methods fail or are difficult to apply. The GET is simple to implement and, unlike a number of other summation procedures, requires no a priori knowledge of the analytic properties of the function underlying the RS series. Application of the GET to the difficult problem of the RS weak-field ground-state eigenvalue series of the hydrogen atom in a magnetic field (quadratic Zeeman effect) yields sums of good accuracy over a very wide range of field strengths up to the most intense fields of 10 14 G. The GET results are compared with those obtained by other summing methods
International Nuclear Information System (INIS)
Gorelikov, G. A.; Fridman, Yu. A.
2013-01-01
The spectra of coupled magnetoelastic waves in a semi-infinite strongly anisotropic easy-plane ferromagnet with a rigidly fixed face are analyzed for two variants of fixation (in the basal plane and perpendicularly to it). The phase states of the system are determined. Differences in the phase diagrams and elementary excitation spectra depending on the choice of the sample fixation plane are considered. When rotational invariance is taken into account, the nonreciprocity effect for the velocities of sound in a crystal appears. It is shown that the velocity of sound in the sample considerably depends on the symmetry of the imposed mechanical boundary conditions. The phase diagrams of the system under investigation are presented
Energy Technology Data Exchange (ETDEWEB)
Sreenivasulu, Gollapudi; Hamilton, Sean L.; Lehto, Piper R.; Srinivasan, Gopalan, E-mail: srinivas@oakland.edu [Physics Department, Oakland University, Rochester, Michigan 48309-4401 (United States); Popov, Maksym [Physics Department, Oakland University, Rochester, Michigan 48309-4401 (United States); Radiophysics Department, Taras Shevchenko National University of Kyiv, Kyiv 01601 (Ukraine); Chavez, Ferman A. [Chemistry Department, Oakland University, Rochester, Michigan 48309-4401 (United States)
2014-02-03
Ferromagnetic-ferroelectric composites show strain mediated coupling between the magnetic and electric sub-systems due to magnetostriction and piezoelectric effects associated with the ferroic phases. We have synthesized core-shell multiferroic nano-composites by functionalizing 10–100 nm barium titanate and nickel ferrite nanoparticles with complementary coupling groups and allowing them to self-assemble in the presence of a catalyst. The core-shell structure was confirmed by electron microscopy and magnetic force microscopy. Evidence for strong strain mediated magneto-electric coupling was obtained by static magnetic field induced variations in the permittivity over 16–18 GHz and polarization and by electric field induced by low-frequency ac magnetic fields.
Strong-field effects in Rabi oscillations between a single state and a superposition of states
International Nuclear Information System (INIS)
Zhdanovich, S.; Milner, V.; Hepburn, J. W.
2011-01-01
Rabi oscillations of quantum population are known to occur in two-level systems driven by spectrally narrow laser fields. In this work we study Rabi oscillations induced by shaped broadband femtosecond laser pulses. Due to the broad spectral width of the driving field, the oscillations are initiated between a ground state and a coherent superposition of excited states, or a ''wave packet,'' rather than a single excited state. Our experiments reveal an intricate dependence of the wave-packet phase on the intensity of the laser field. We confirm numerically that the effect is associated with the strong-field nature of the interaction and provide a qualitative picture by invoking a simple theoretical model.
International Nuclear Information System (INIS)
Chou, C-P; Lee, T K; Ho, C-M
2009-01-01
We examine the strong correlation effects of the d-wave superconducting state by including the Gutzwiller projection for no electron double occupancy at each lattice site. The spectral weights (SW's) for adding and removing an electron on the projected superconducting state, the ground state of the 2-dimensional t-t'-t - J model with moderate doped holes describing the high T c cuprates, are studied numerically on finite lattices and compared with the observation made by low-temperature tunneling (particle asymmetry of tunneling conductance) and angle-resolved photoemission (SW transfer from the projected Fermi liquid state) spectroscopies. The contrast with the d-wave case without projection is alo presented.
Lin, Shih-Yin; Singh, Chandralekha
2015-12-01
It is well known that introductory physics students often have alternative conceptions that are inconsistent with established physical principles and concepts. Invoking alternative conceptions in the quantitative problem-solving process can derail the entire process. In order to help students solve quantitative problems involving strong alternative conceptions correctly, appropriate scaffolding support can be helpful. The goal of this study is to examine how different scaffolding supports involving analogical problem-solving influence introductory physics students' performance on a target quantitative problem in a situation where many students' solution process is derailed due to alternative conceptions. Three different scaffolding supports were designed and implemented in calculus-based and algebra-based introductory physics courses involving 410 students to evaluate the level of scaffolding needed to help students learn from an analogical problem that is similar in the underlying principles involved but for which the problem-solving process is not derailed by alternative conceptions. We found that for the quantitative problem involving strong alternative conceptions, simply guiding students to work through the solution of the analogical problem first was not enough to help most students discern the similarity between the two problems. However, if additional scaffolding supports that directly helped students examine and repair their knowledge elements involving alternative conceptions were provided, e.g., by guiding students to contemplate related issues and asking them to solve the targeted problem on their own first before learning from the analogical problem provided, students were more likely to discern the underlying similarities between the problems and avoid getting derailed by alternative conceptions when solving the targeted problem. We also found that some scaffolding supports were more effective in the calculus-based course than in the algebra
Effective model with strong Kitaev interactions for α -RuCl3
Suzuki, Takafumi; Suga, Sei-ichiro
2018-04-01
We use an exact numerical diagonalization method to calculate the dynamical spin structure factors of three ab initio models and one ab initio guided model for a honeycomb-lattice magnet α -RuCl3 . We also use thermal pure quantum states to calculate the temperature dependence of the heat capacity, the nearest-neighbor spin-spin correlation function, and the static spin structure factor. From the results obtained from these four effective models, we find that, even when the magnetic order is stabilized at low temperature, the intensity at the Γ point in the dynamical spin structure factors increases with increasing nearest-neighbor spin correlation. In addition, we find that the four models fail to explain heat-capacity measurements whereas two of the four models succeed in explaining inelastic-neutron-scattering experiments. In the four models, when temperature decreases, the heat capacity shows a prominent peak at a high temperature where the nearest-neighbor spin-spin correlation function increases. However, the peak temperature in heat capacity is too low in comparison with that observed experimentally. To address these discrepancies, we propose an effective model that includes strong ferromagnetic Kitaev coupling, and we show that this model quantitatively reproduces both inelastic-neutron-scattering experiments and heat-capacity measurements. To further examine the adequacy of the proposed model, we calculate the field dependence of the polarized terahertz spectra, which reproduces the experimental results: the spin-gapped excitation survives up to an onset field where the magnetic order disappears and the response in the high-field region is almost linear. Based on these numerical results, we argue that the low-energy magnetic excitation in α -RuCl3 is mainly characterized by interactions such as off-diagonal interactions and weak Heisenberg interactions between nearest-neighbor pairs, rather than by the strong Kitaev interactions.
Effects of strong and electromagnetic correlations on neutrino interactions in dense matter
International Nuclear Information System (INIS)
Reddy, S.; Prakash, M.; Lattimer, J.M.; Reddy, S.; Pons, J.A.
1999-01-01
An extensive study of the effects of correlations on both charged and neutral current weak interaction rates in dense matter is performed. Both strong and electromagnetic correlations are considered. The propagation of particle-hole interactions in the medium plays an important role in determining the neutrino mean free paths. The effects due to Pauli blocking and density, spin, and isospin correlations in the medium significantly reduce the neutrino cross sections. As a result of the lack of experimental information at high density, these correlations are necessarily model dependent. For example, spin correlations in nonrelativistic models are found to lead to larger suppressions of neutrino cross sections compared to those of relativistic models. This is due to the tendency of the nonrelativistic models to develop spin instabilities. Notwithstanding the above caveats, and the differences between nonrelativistic and relativistic approaches such as the spin- and isospin-dependent interactions and the nucleon effective masses, suppressions of order 2 - 3, relative to the case in which correlations are ignored, are obtained. Neutrino interactions in dense matter are especially important for supernova and early neutron star evolution calculations. The effects of correlations for protoneutron star evolution are calculated. Large effects on the internal thermodynamic properties of protoneutron stars, such as the temperature, are found. These translate into significant early enhancements in the emitted neutrino energies and fluxes, especially after a few seconds. At late times, beyond about 10 s, the emitted neutrino fluxes decrease more rapidly compared to simulations without the effects of correlations, due to the more rapid onset of neutrino transparency in the protoneutron star. copyright 1999 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Franco de Carvalho, F. [Centre Européen de Calcul Atomique et Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland); Tavernelli, I. [IBM Research GmbH, Zurich Research Laboratory, 8803 Ruschlikon (Switzerland)
2015-12-14
In this work, we derive a method to perform trajectory-based nonadiabatic dynamics that is able to describe both nonadiabatic transitions and intersystem crossing events (transitions between states of different spin-multiplicity) at the same level of theory, namely, time-dependent density functional theory (TDDFT). To this end, we combined our previously developed TDDFT-based trajectory surface hopping scheme with an accurate and efficient algorithm for the calculation of the spin-orbit coupling (SOC) matrix elements. More specifically, we designed two algorithms for the calculation of intersystem crossing transitions, one based on an extended Tully’s surface hopping scheme including SOC and the second based on a Landau-Zener approximation applied to the spin sector of the electronic Hilbert space. This development allows for the design of an efficient on-the-fly nonadiabatic approach that can handle, on an equal footing, nonadiabatic and intersystem crossing transitions. The method is applied to the study of the photophysics of sulfur dioxide (SO{sub 2}) in gas and liquid phases.
Between ethylene and polyenes--the non-adiabatic dynamics of cis-dienes
DEFF Research Database (Denmark)
Kuhlman, Thomas Scheby; Glover, William J; Mori, Toshifumi
2012-01-01
Using Ab Initio Multiple Spawning (AIMS) with a Multi-State Multi-Reference Perturbation theory (MS-MR-CASPT2) treatment of the electronic structure, we have simulated the non-adiabatic excited state dynamics of cyclopentadiene (CPD) and 1,2,3,4-tetramethyl-cyclopentadiene (Me4-CPD) following exc...
Ideal quantum gas in an expanding cavity: nature of nonadiabatic force.
Nakamura, K; Avazbaev, S K; Sobirov, Z A; Matrasulov, D U; Monnai, T
2011-04-01
We consider a quantum gas of noninteracting particles confined in the expanding cavity and investigate the nature of the nonadiabatic force which is generated from the gas and acts on the cavity wall. First, with use of the time-dependent canonical transformation, which transforms the expanding cavity to the nonexpanding one, we can define the force operator. Second, applying the perturbative theory, which works when the cavity wall begins to move at time origin, we find that the nonadiabatic force is quadratic in the wall velocity and thereby does not break the time-reversal symmetry, in contrast with general belief. Finally, using an assembly of the transitionless quantum states, we obtain the nonadiabatic force exactly. The exact result justifies the validity of both the definition of the force operator and the issue of the perturbative theory. The mysterious mechanism of nonadiabatic transition with the use of transitionless quantum states is also explained. The study is done for both cases of the hard- and soft-wall confinement with the time-dependent confining length. ©2011 American Physical Society
Non-adiabatic molecular dynamic simulations of opening reaction of molecular junctions
Czech Academy of Sciences Publication Activity Database
Zobač, Vladimír; Lewis, J.P.; Jelínek, Pavel
2016-01-01
Roč. 27, č. 28 (2016), 1-8, č. článku 285202. ISSN 0957-4484 R&D Projects: GA ČR(CZ) GA14-02079S Institutional support: RVO:68378271 Keywords : non-adiabatic molecular dynamics * molecular junctions * molecular switches * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.440, year: 2016
TREATMENT OF NONADIABATIC TRANSITIONS BY DENSITY-MATRIX EVOLUTION AND MOLECULAR-DYNAMICS SIMULATIONS
MAVRI, J; BERENDSEN, HJC
1994-01-01
A density matrix evolution (DME) method (H.J.C. Berendsen and J. Mavri, J. Phys. Chem., 97 (1993) 13469) to simulate the dynamics of quantum systems embedded in a classical environment is presented. The DME method allows treatment of nonadiabatic transitions. As numerical examples the collinear
Channel-closing effects in strong-field ionization by a bicircular field
Milošević, D. B.; Becker, W.
2018-03-01
Channel-closing effects, such as threshold anomalies and resonantlike intensity-dependent enhancements in strong-field ionization by a bicircular laser field are analyzed. A bicircular field consists of two coplanar corotating or counter-rotating circularly polarized fields having different frequencies. For the total detachment rate of a negative ion by a bicircular field we observe threshold anomalies and explain them using the Wigner threshold law and energy and angular momentum conservation. For the corotating bicircular case, these effects are negligible, while for the counter-rotating case they are pronounced and their position depends on the magnetic quantum number of the initial state. For high-order above-threshold ionization of rare-gas atoms by a counter-rotating bicircular laser field we observe very pronounced intensity-dependent enhancements. We find all four types of threshold anomalies known from collision theory. Contrary to the case of linear polarization, channel-closing effects for a bicircular field are visible also in the cutoff region of the electron energy spectrum, which is explained using quantum-orbit theory.
Strong quantum-confined stark effect in germanium quantum-well structures on silicon
International Nuclear Information System (INIS)
Kuo, Y.; Lee, Y. K.; Gei, Y.; Ren, S; Roth, J. E.; Miller, D. A.; Harris, J. S.
2006-01-01
Silicon is the dominant semiconductor for electronics, but there is now a growing need to integrate such component with optoelectronics for telecommunications and computer interconnections. Silicon-based optical modulators have recently been successfully demonstrated but because the light modulation mechanisms in silicon are relatively weak, long (for example, several millimeters) devices or sophisticated high-quality-factor resonators have been necessary. Thin quantum-well structures made from III-V semiconductors such as GaAs, InP and their alloys exhibit the much stronger Quantum-Confined Stark Effect (QCSE) mechanism, which allows modulator structures with only micrometers of optical path length. Such III-V materials are unfortunately difficult to integrate with silicon electronic devices. Germanium is routinely integrated with silicon in electronics, but previous silicon-germanium structures have also not shown strong modulation effects. Here we report the discovery of the QCSE, at room temperature, in thin germanium quantum-well structures grown on silicon. The QCSE here has strengths comparable to that in III-V materials. Its clarity and strength are particularly surprising because germanium is an indirect gap semiconductor, such semiconductors often display much weak optical effects than direct gap materials (such as the III-V materials typically used for optoelectronics). This discovery is very promising for small, high-speed, low-power optical output devices fully compatible with silicon electronics manufacture. (author)
Strong mechanically induced effects in DC current-biased suspended Josephson junctions
McDermott, Thomas; Deng, Hai-Yao; Isacsson, Andreas; Mariani, Eros
2018-01-01
Superconductivity is a result of quantum coherence at macroscopic scales. Two superconductors separated by a metallic or insulating weak link exhibit the AC Josephson effect: the conversion of a DC voltage bias into an AC supercurrent. This current may be used to activate mechanical oscillations in a suspended weak link. As the DC-voltage bias condition is remarkably difficult to achieve in experiments, here we analyze theoretically how the Josephson effect can be exploited to activate and detect mechanical oscillations in the experimentally relevant condition with purely DC current bias. We unveil how changing the strength of the electromechanical coupling results in two qualitatively different regimes showing dramatic effects of the oscillations on the DC-voltage characteristic of the device. These include the appearance of Shapiro-type plateaus for weak coupling and a sudden mechanically induced retrapping for strong coupling. Our predictions, measurable in state-of-the-art experimental setups, allow the determination of the frequency and quality factor of the resonator using DC only techniques.
Debecker, Sara; Dinh, Khuong V; Stoks, Robby
2017-02-21
As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species' ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and low-latitude populations. By integrating these mechanisms into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies. These results highlight that a more complete life-cycle approach that incorporates the possibility of delayed interactions between contaminants and warming in a geographical context is crucial for a more realistic risk assessment in a warming world.
Iovine, G.; D'Ambrosio, D.
2003-04-01
Cellular Automata models do represent a valid method for the simulation of complex phenomena, when these latter can be described in "a-centric" terms - i.e. through local interactions within a discrete time-space. In particular, flow-type landslides (such as debris flows) can be viewed as a-centric dynamical system. SCIDDICA S4b, the last release of a family of two-dimensional hexagonal Cellular Automata models, has recently been developed for simulating debris flows characterised by strong inertial effects. It has been derived by progressively enriching an initial simplified CA model, originally derived for simulating very simple cases of slow-moving flow-type landslides. In S4b, by applying an empirical strategy, the inertial characters of the flowing mass have been translated into CA terms. In the transition function of the model, the distribution of landslide debris among the cells is computed by considering the momentum of the debris which move among the cells of the neighbourhood, and privileging the flow direction. By properly setting the value of one of the global parameters of the model (the "inertial factor"), the mechanism of distribution of the landslide debris among the cells can be influenced in order to emphasise the inertial effects, according to the energy of the flowing mass. Moreover, the high complexity of both the model and of the phenomena to be simulated (e.g. debris flows characterised by severe erosion along their path, and by strong inertial effects) suggested to employ an automated technique of evaluation, for the determination of the best set of global parameters. Accordingly, the calibration of the model has been performed through Genetic Algorithms, by considering several real cases of study: these latter have been selected among the population of landslides triggered in Campania (Southern Italy) in May 1998 and December 1999. Obtained results are satisfying: errors computed by comparing the simulations with the map of the real
Atmospheres and spectra of strongly magnetized neutron stars - II. The effect of vacuum polarization
Ho, Wynn C. G.; Lai, Dong
2003-01-01
We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B= 1014-1015 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few ×106 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV <~E<~ a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high-energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.
Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum
Fujiwara, Yoshihisa; Tomishige, Masahiko; Itoh, Yasuhiro; Fujiwara, Masao; Shibata, Naho; Kosaka, Toshikazu; Hosoya, Hiroshi; Tanimoto, Yoshifumi
2006-05-01
Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum was studied by using a superconducting magnet. Around a centre of a round vessel, random swimming at 0 T and aligned swimming parallel to the magnetic field (MF) of 8 T were observed. Near a wall of the vessel, however, swimming round and round along the wall at 0 T and aligned swimming of turning at right angles upon collision with the wall, which was remarkable around 1-4 T, were detected. It was experimentally revealed that the former MF-induced parallel swimming at the vessel centre was caused physicochemically by the parallel magnetic orientation of the cell itself. From magnetic field dependence of the extent of the orientation, the magnetic susceptibility anisotropy (χ ∥-χ ⊥) was first obtained to be 3.4× 10-23 emu cell-1 at 298 K for Paramecium caudatum. The orientation of the cell was considered to result from the magnetic orientation of the cell membrane. On the other hand, although mechanisms of the latter swimming near the vessel wall regardless of the absence and presence of the magnetic field are unclear at present, these experimental results indicate that whether the cell exists near the wall alters the magnetic field effect on the swimming in the horizontal magnetic field.
International Nuclear Information System (INIS)
Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo
2011-01-01
Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields. (author)
Iliopoulos, Nikos; Thanopulos, Ioannis; Yannopapas, Vassilios; Paspalakis, Emmanuel
2018-03-01
We study the spontaneous emission of a two-level quantum emitter next to a plasmonic nanoparticle beyond the Markovian approximation and the rotating-wave approximation (RWA) by combining quantum dynamics and classical electromagnetic calculations. For emitters with decay times in the picosecond to nanosecond time regime, as well as located at distances from the nanoparticle up to its radius, the dynamics with and without the RWA and the transition from the non-Markovian to the Markovian regime are investigated. For emitters with longer decay times, the Markov approximation proves to be adequate for distances larger than half the nanoparticle radius. However, the RWA is correct for all distances of the emitter from the nanoparticle. For short decay time emitters, the Markov approximation and RWA are both inadequate, with only the RWA becoming valid again at a distance larger than half the nanoparticle radius. We also show that the entanglement dynamics of two initially entangled qubits interacting independently with the nanoparticle may have a strong non-Markovian character when counter-rotating effects are included. Interesting effects such as entanglement sudden death, periodic entanglement revival, entanglement oscillations, and entanglement trapping are further observed when different initial two-qubit states and different distances between the qubit and the nanoparticle are considered.
Mechanical effects of strong measurement: back-action noise and cooling
Schwab, Keith
2007-03-01
Our recent experiments show that it is now possible to prepare and measure mechanical systems with thermal occupation factors of N˜25 and perform continuous position measurements close to the limits required by the Heisenberg Uncertainty Principle (1). I will discuss our back-action measurements with nanomechanical structures strongly coupled to single electron transistors. We have been able to observe the stochastic back-action forces exerted by the SET as well as a cooling effect which has analogies to cooling in optical cavities. Furthermore, I will discuss progress using optical fields coupled to mechanical modes which show substantial cooling using the pondermotive effects of the photons impacting a flexible dielectric mirror (2). Both of these techniques pave the way to demonstrating the true quantum properties of a mechanical device: squeezed states, superposition states, and entangled states. (1) ``Quantum Measurement Backaction and Cooling Observed with a Nanomechanical Resonator,'' A. Naik, O. Buu, M.D. LaHaye, M.P. Blencowe, A.D. Armour, A.A. Clerk, K.C. Schwab, Nature 443, 193 (2006). (2) ``Self-cooling of a micro-mirror by radiation pressure,'' S. Gigan, H.R. Boehm, M. Patemostro, F. Blaser, G. Langer, J. Hertzberg, K. Schwab, D. Baeuerle, M. Aspelmeyer, A. Zeilinger, Nature 444, 67 (2006).
An effective strong-coupling theory of composite particles in UV-domain
Xue, She-Sheng
2017-05-01
We briefly review the effective field theory of massive composite particles, their gauge couplings and characteristic energy scale in the UV-domain of UV-stable fixed point of strong four-fermion coupling, then mainly focus the discussions on the decay channels of composite particles into the final states of the SM gauge bosons, leptons and quarks. We calculate the rates of composite bosons decaying into two gauge bosons γγ, γZ 0, W + W -, Z 0 Z 0 and give the ratios of decay rates of different channels depending on gauge couplings only. It is shown that a composite fermion decays into an elementary fermion and a composite boson, the latter being an intermediate state decays into two gauge bosons, leading to a peculiar kinematics of final states of a quark (or a lepton) and two gauge bosons. These provide experimental implications of such an effective theory of composite particles beyond the SM. We also present some speculative discussions on the channels of composite fermions decaying into W W , W Z and ZZ two boson-tagged jets with quark jets, or to four-quark jets. Moreover, at the same energy scale of composite particles produced in high-energy experiments, composite particles are also produced by high-energy sterile neutrino (dark matter) collisions, their decays lead to excesses of cosmic ray particles in space and signals of SM particles in underground laboratories.
An effective strong-coupling theory of composite particles in UV-domain
Energy Technology Data Exchange (ETDEWEB)
Xue, She-Sheng [ICRANet,Piazzale della Repubblica 10, 10-65122, Pescara (Italy); Physics Department, Sapienza University of Rome,Piazzale Aldo Moro 5, 00185 Roma (Italy)
2017-05-29
We briefly review the effective field theory of massive composite particles, their gauge couplings and characteristic energy scale in the UV-domain of UV-stable fixed point of strong four-fermion coupling, then mainly focus the discussions on the decay channels of composite particles into the final states of the SM gauge bosons, leptons and quarks. We calculate the rates of composite bosons decaying into two gauge bosons γγ, γZ{sup 0}, W{sup +}W{sup −}, Z{sup 0}Z{sup 0} and give the ratios of decay rates of different channels depending on gauge couplings only. It is shown that a composite fermion decays into an elementary fermion and a composite boson, the latter being an intermediate state decays into two gauge bosons, leading to a peculiar kinematics of final states of a quark (or a lepton) and two gauge bosons. These provide experimental implications of such an effective theory of composite particles beyond the SM. We also present some speculative discussions on the channels of composite fermions decaying into WW, WZ and ZZ two boson-tagged jets with quark jets, or to four-quark jets. Moreover, at the same energy scale of composite particles produced in high-energy experiments, composite particles are also produced by high-energy sterile neutrino (dark matter) collisions, their decays lead to excesses of cosmic ray particles in space and signals of SM particles in underground laboratories.
Rahpeyma, Sahar
2016-08-11
The rock site characterization for earthquake engineering applications in Iceland is common due to the easily exposed older bedrock and more recent volcanic lava rock. The corresponding site amplification is generally assumed to be low but has not been comprehensively quantified, especially for volcanic rock. The earthquake strong-motion of the Mw6.3 Ölfus earthquake on 29 May 2008 and 1705 of its aftershocks recorded on the first small-aperture strong-motion array (ICEARRAY I) in Iceland showed consistent and significant variations in ground motion amplitudes over short distances (<2 km) in an urban area located mostly on lava rock. This study analyses the aftershock recordings to quantify the local site effects using the Horizontal to Vertical Spectral Ratio (HVSR) and Standard Spectral Ratio (SSR) methods. Additionally, microseismic data has been collected at array stations and analyzed using the HVSR method. The results between the methods are consistent and show that while the amplification levels remain relatively low, the predominant frequency varies systematically between stations and is found to correlate with the geological units. In particular, for stations on lava rock the underlying geologic structure is characterized by repeated lava-soil stratigraphy characterized by reversals in the shear wave velocity with depth. As a result, standard modeling of HVSR using vertically incident body waves does not apply. Instead, modeling the soil structure as a two-degree-of-freedom dynamic system is found to capture the observed predominant frequencies of site amplification. The results have important implications for earthquake resistant design of structures on rock sites characterized by velocity reversals. © 2016 Elsevier Ltd
Effective potential in the strong-coupling lattice QCD with next-to-next-to-learning order effects
International Nuclear Information System (INIS)
Nakano, Takashi Z.; Miura, Kohtaroh; Ohnishi, Akira
2010-01-01
We derive an analytic expression of the effective potential at finite temperature (T) and chemical potential (μ) in the strong-coupling lattice QCD for color SU(3) including next-to-next-to-leading order (NNLO) effects in the strong coupling expansion. NNLO effective action terms are systematically evaluated in the leading order of the large dimensional (1/d) expansion, and are found to come from some types of connected two-plaquette configurations. We apply the extended Hubbard-Stratonovich transformation and a gluonic-dressed fermion technique to the effective action, and obtain the effective potential as a function of T, μ, and two order parameters: chiral condensate and vector potential field. The next-to-leading order (NLO) and NNLO effects result in modifications of the wave function renormalization factor, quark mass, and chemical potential. We find that T c,μ =0 and μ c,T =0 are similar to the NLO results, whereas the position of the critical point is sensitive to NNLO corrections. (author)
Effects of multi-photon interferences from internally generated fields in strongly resonant systems
International Nuclear Information System (INIS)
Deng, Lu; Payne, Marvin G.; Garrett, William R.
2006-01-01
In studies of various nonlinear optical phenomena, strong resonant features in the atomic or molecular response to multi-photon driven processes have been used to greatly enhance the visibility of otherwise weak higher-order processes. However, there are well defined circumstances where a multi-photon-resonant response of a target system leads to the generation of one or more new electromagnetic fields that can drastically change the overall system response from what would be expected from the imposed laser fields alone. New effects can occur and dominate some aspects of the nonlinear optical response because of the constructive or destructive interference between transition amplitudes along multiple excitation pathways between a given set of optically coupled states, where one of the pathways involve internally generated field(s). Under destructive interference some resonant enhancements can become completely canceled (suppressed). This review focuses on the class of optical interference effects associated with internally generated fields, that have been found to be capable of influencing a very significant number of basic physical phenomena in gas or vapor phase systems. It provides a historical overview of experimental and theoretical developments and a modern understanding of the underlying physics and its various manifestations that include: suppression of multi-photon excitation processes, suppression of stimulated emissions (Raman, hyper-Raman, and optically pumped stimulated emissions), saturation of parametric wave-mixing, pressure and beam-geometry dependent shifting of multi-photon-resonant absorption lines, and the suppression of Autler-Townes splitting and ac-stark shifts. Additionally, optical interference effects in some modern contexts, such as achieving multi-photon induced transparency, establishing single-photon self-interference based induced transparency, and generating entangled single photon states, are reviewed
Profiling the overdamped dynamics of a nonadiabatic system
Energy Technology Data Exchange (ETDEWEB)
Sarkar, Prasun [Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700009 (India); Shit, Anindita [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103 (India); Banik, Suman K., E-mail: skbanik@jcbose.ac.in [Department of Chemistry, Bose Institute, 93/1 A P C Road, Kolkata 700009 (India)
2015-09-08
Graphical abstract: The theoretical analysis that is addressed here can be used to illustrate both a qualitative and a quantitative understanding of the dynamics of a particle in the presence of an external probe. - Highlights: • Interaction of systems with strong fields results in many interesting observations. • The relevant systems are characterized by an extremely high degree of control. • The theory that is addressed here is useful to investigate the transport process. • Effective to understand the trapping mechanism in a rapidly oscillating potential. • Useful to study the dynamics of particles in the presence of an external probe. - Abstract: Rapidly oscillating time-periodic potentials with a vanishing time average have been exploited to investigate the dynamics of an overdamped particle. Using the multiple scale perturbation theory, it has been shown that the dynamics can be adequately characterized by an explicitly time-independent effective potential. The resulting “effective equation of motion” can offer various avenues to handle the dynamics of the system driven by a high-frequency field. We study the effects of the field parameters on the mobility of the overdamped particle moving in the effective potential. The variation of the mobility with the field parameters is associated with the interplay of spatially periodic gradients, time periodic modulation and thermal noise in the overdamped region. Good agreement between the simulations and theoretical estimates validates our methodology that captures the constitutional features ruling the dynamics in the overdamped limit. The results observed here can also be extended to the quantum system.
Effect of initial perturbation amplitude on Richtmyer-Meshkov flows induced by strong shocks
Energy Technology Data Exchange (ETDEWEB)
Dell, Z.; Abarzhi, S. I., E-mail: snezhana.abarzhi@gmail.com, E-mail: sabarji@andrew.cmu.edu [Mellon College of Science and Carnegie Mellon University – Qatar, Carnegie Mellon University, Pittsburgh, Pennsylvania 15231 (United States); Stellingwerf, R. F. [Stellingwerf Consulting, Huntsville, Alabama 35803 (United States)
2015-09-15
We systematically study the effect of the initial perturbation on Richtmyer-Meshkov (RM) flows induced by strong shocks in fluids with contrasting densities. Smooth Particle Hydrodynamics simulations are employed. A broad range of shock strengths and density ratios is considered. The amplitude of the initial single mode sinusoidal perturbation of the interface varies from 0% to 100% of its wavelength. The simulations results are compared, wherever possible, with four rigorous theories, and with other experiments and simulations, achieving good quantitative and qualitative agreement. Our study is focused on early time dynamics of the Richtmyer-Meshkov instability (RMI). We analyze the initial growth-rate of RMI immediately after the shock passage, when the perturbation amplitude increases linearly with time. For the first time, to the authors' knowledge, we find that the initial growth-rate of RMI is a non-monotone function of the initial perturbation amplitude, thus restraining the amount of energy that can be deposited by the shock at the interface. The maximum value of the initial growth-rate depends on the shock strength and the density ratio, whereas the corresponding value of the initial perturbation amplitude depends only slightly on the shock strength and density ratio.
Süsal, Caner; Pelzl, Steffen; Opelz, Gerhard
2003-10-27
The influence of human leukocyte antigen (HLA) matching on graft survival is greater in patients with preformed lymphocytotoxic antibodies than in nonsensitized patients. Pretransplant serum soluble CD30 (sCD30) affects graft outcome independently of presensitization status. The impact of HLA compatibility on kidney transplant survival was analyzed in 3980 nonsensitized first cadaveric kidney recipients in relation to the pretransplant serum sCD30 content. Although HLA compatibility influenced graft outcome only marginally in nonsensitized recipients with low sCD30 (at 3 years: P=0.0095; at 5 years: P=0.1033), a strong HLA matching effect was observed in nonsensitized recipients with high sCD30 (at 3 years: PsCD30 benefit from an HLA well-matched kidney. Patients should be tested for sCD30 while on the waiting list for a kidney transplant, and HLA well-matched kidneys should be allocated to patients with high sCD30.
Disorder effects on helical edge transport in graphene under a strong tilted magnetic field
Huang, Chunli; Cazalilla, Miguel A.
2015-10-01
In a recent experiment, Young et al. [Nature (London) 505, 528 (2014), 10.1038/nature12800] observed a metal to insulator transition as well as transport through helical edge states in monolayer graphene under a strong, tilted magnetic field. Under such conditions, the bulk is a magnetic insulator which can exhibit metallic conduction through helical edges. It was found that the two-terminal conductance of the helical channels deviates from the expected quantized value (=e2/h per edge, at zero temperature). Motivated by this observation, we study the effect of disorder on the conduction through the edge channels. We show that, unlike for helical edges of topological insulators in semiconducting quantum wells, a disorder Rashba spin-orbit coupling does not lead to backscattering, at least to leading order. Instead, we find that the lack of perfect antialignment of the electron spins in the helical channels to be the most likely cause for backscattering arising from scalar (i.e., spin-independent) impurities. The intrinsic spin-orbit coupling and other time-reversal symmetry-breaking and/or sublattice parity-breaking potentials also lead to (subleading) corrections to the channel conductance.
Quantum Fluctuations and the Unruh effect in strongly-coupled conformal field theories
Cáceres, Elena; Chernicoff, Mariano; Güijosa, Alberto; Pedraza, Juan F.
2010-06-01
Through the AdS/CFT correspondence, we study a uniformly accelerated quark in the vacuum of strongly-coupled conformal field theories in various dimensions, and determine the resulting stochastic fluctuations of the quark trajectory. From the perspective of an inertial observer, these are quantum fluctuations induced by the gluonic radiation emitted by the accelerated quark. From the point of view of the quark itself, they originate from the thermal medium predicted by the Unruh effect. We scrutinize the relation between these two descriptions in the gravity side of the correspondence, and show in particular that upon transforming the conformal field theory from Rindler space to the open Einstein universe, the acceleration horizon disappears from the boundary theory but is preserved in the bulk. This transformation allows us to directly connect our calculation of radiation-induced fluctuations in vacuum with the analysis by de Boer et al. of the Brownian motion of a quark that is on average static within a thermal medium. Combining this same bulk transformation with previous results of Emparan, we are also able to compute the stress-energy tensor of the Unruh thermal medium.
Source, propagation and site effects: impact on mapping strong ground motion in Bucharest area
International Nuclear Information System (INIS)
Radulian, R.; Kuznetsov, I.; Panza, G.F.
2004-01-01
Achievements in the framework of the NATO SfP project 972266 focused on the impact of Vrancea earthquakes on the security of Bucharest urban area are presented. The problem of Bucharest city security to Vrancea earthquakes is discussed in terms of numerical modelling of seismic motion and intermediate term earthquake prediction. A hybrid numerical scheme developed by Faeh et al. (1990; 1993) for frequencies up to 1 Hz is applied for the realistic modelling of the seismic ground motion in Bucharest. The method combines the modal summation for the 1D bedrock model and the finite differences for the 2D local structure model. All the factors controlling the ground motion at the site are considered: source, propagation and site effects, respectively. The input data includes the recent records provided by the digital accelerometer network developed within the Romanian-German CRC461 cooperation programme and CALIXTO'99, VRANCEA'99, VRANCEA2001 experiments. The numerical simulation proves to be a powerful tool in mapping the strong ground motion for realistic structures, reproducing acceptably from engineering point of view the observations. A new model of the Vrancea earthquake scaling is obtained and implications for the determination of the seismic motion parameters are analyzed. The role of the focal mechanism and attenuation properties upon the amplitude and spectral content of the ground motion are outlined. CN algorithm is applied for predicting Vrancea earthquakes. Finally, implications for the disaster management strategy are discussed. (authors)
Effect of dipole polarizability on positron binding by strongly polar molecules
International Nuclear Information System (INIS)
Gribakin, G F; Swann, A R
2015-01-01
A model for positron binding to polar molecules is considered by combining the dipole potential outside the molecule with a strongly repulsive core of a given radius. Using existing experimental data on binding energies leads to unphysically small core radii for all of the molecules studied. This suggests that electron–positron correlations neglected in the simple model play a large role in determining the binding energy. We account for these by including the polarization potential via perturbation theory and non-perturbatively. The perturbative model makes reliable predictions of binding energies for a range of polar organic molecules and hydrogen cyanide. The model also agrees with the linear dependence of the binding energies on the polarizability inferred from the experimental data (Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203). The effective core radii, however, remain unphysically small for most molecules. Treating molecular polarization non-perturbatively leads to physically meaningful core radii for all of the molecules studied and enables even more accurate predictions of binding energies to be made for nearly all of the molecules considered. (paper)
Strong gravity effects of rotating black holes: quasi-periodic oscillations
International Nuclear Information System (INIS)
Aliev, Alikram N; Esmer, Göksel Daylan; Talazan, Pamir
2013-01-01
We explore strong gravity effects of the geodesic motion in the spacetime of rotating black holes in general relativity and braneworld gravity. We focus on the description of the motion in terms of three fundamental frequencies: the orbital frequency, the radial and vertical epicyclic frequencies. For a Kerr black hole, we perform a detailed numerical analysis of these frequencies at the innermost stable circular orbits and beyond them as well as at the characteristic stable orbits, at which the radial epicyclic frequency attains its highest value. We find that the values of the epicyclic frequencies for a class of stable orbits exhibit good qualitative agreement with the observed frequencies of the twin peaks quasi-periodic oscillations (QPOs) in some black hole binaries. We also find that at the characteristic stable circular orbits, where the radial (or the vertical) epicyclic frequency has maxima, the vertical and radial epicyclic frequencies exhibit an approximate 2:1 ratio even in the case of near-extreme rotation of the black hole. Next, we perform a similar analysis of the fundamental frequencies for a rotating braneworld black hole and argue that the existence of such a black hole with a negative tidal charge, whose angular momentum exceeds the Kerr bound in general relativity, does not confront with the observations of high-frequency QPOs. (paper)
Hole dynamics and spin currents after ionization in strong circularly polarized laser fields
International Nuclear Information System (INIS)
Barth, Ingo; Smirnova, Olga
2014-01-01
We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)
Dopamine D(1) receptor deletion strongly reduces neurotoxic effects of methamphetamine.
Ares-Santos, S; Granado, N; Oliva, I; O'Shea, E; Martin, E D; Colado, M I; Moratalla, R
2012-02-01
Methamphetamine (METH) is a potent, highly addictive psychostimulant consumed worldwide. In humans and experimental animals, repeated exposure to this drug induces persistent neurodegenerative changes. Damage occurs primarily to dopaminergic neurons, accompanied by gliosis. The toxic effects of METH involve excessive dopamine (DA) release, thus DA receptors are highly likely to play a role in this process. To define the role of D(1) receptors in the neurotoxic effects of METH we used D(1) receptor knock-out mice (D(1)R(-/-)) and their WT littermates. Inactivation of D(1)R prevented METH-induced dopamine fibre loss and hyperthermia, and increases in gliosis and pro-inflammatory molecules such as iNOS in the striatum. In addition, D(1)R inactivation prevented METH-induced loss of dopaminergic neurons in the substantia nigra. To explore the relationship between hyperthermia and neurotoxicity, METH was given at high ambient temperature (29 °C). In this condition, D(1)R(-/-) mice developed hyperthermia following drug delivery and the neuroprotection provided by D(1)R inactivation at 23 °C was no longer observed. However, reserpine, which empties vesicular dopamine stores, blocked hyperthermia and strongly potentiated dopamine toxicity in D(1)R(-/-) mice, suggesting that the protection afforded by D(1)R inactivation is due to both hypothermia and higher stored vesicular dopamine. Moreover, electrical stimulation evoked higher DA overflow in D(1)R(-/-) mice as demonstrated by fast scan cyclic voltammetry despite their lower basal DA content, suggesting higher vesicular DA content in D(1)R(-/-) than in WT mice. Altogether, these results indicate that the D(1)R plays a significant role in METH-induced neurotoxicity by mediating drug-induced hyperthermia and increasing the releasable cytosolic DA pool. Copyright © 2011. Published by Elsevier Inc.
Autler-Townes effect in a strongly driven electromagnetically induced transparency resonance
International Nuclear Information System (INIS)
Yang Lijun; Zhang Lianshui; Li Xiaoli; Han Li; Fu Guangsheng; Manson, Neil B.; Suter, Dieter; Wei Changjiang
2005-01-01
In this paper we study the nonlinear behavior of an electromagnetically induced transparency (EIT) resonance subject to a coherent driving field. The EIT is associated with a Λ three-level system where two hyperfine levels within an electronic ground state are coupled to a common excited state level by a coupling field and a probe field. In addition there is an radio-frequency (rf) field driving a hyperfine transition within the ground state. The paper contrasts two different situations. In one case the rf-driven transition shares a common level with the probed transition and in the second case it shares a common level with the coupled transition. In both cases the EIT resonance is split into a doublet and the characteristics of the EIT doublet are determined by the strength and frequency of the rf-driving field. The doublet splitting originates from the rf-field induced dynamic Stark effect and has close analogy with the Autler-Townes effect observed in three-level pump-probe spectroscopy study. The situation changes when the rf field is strong and the two cases are very different. One is analogous to two Λ three-level systems with EIT resonance associated with each. The other corresponds to a doubly driven three-level system with rf-field-induced electromagnetically induced absorption resonance. The two situations are modeled using numerical solutions of the relevant equation of motion of density matrix. In addition a physical account of their behaviors is given in terms of a dressed state picture
Beyond Ehrenfest: correlated non-adiabatic molecular dynamics
International Nuclear Information System (INIS)
Horsfield, Andrew P; Bowler, D R; Fisher, A J; Todorov, Tchavdar N; Sanchez, Cristian G
2004-01-01
A method for introducing correlations between electrons and ions that is computationally affordable is described. The central assumption is that the ionic wavefunctions are narrow, which makes possible a moment expansion for the full density matrix. To make the problem tractable we reduce the remaining many-electron problem to a single-electron problem by performing a trace over all electronic degrees of freedom except one. This introduces both one- and two-electron quantities into the equations of motion. Quantities depending on more than one electron are removed by making a Hartree-Fock approximation. Using the first-moment approximation, we perform a number of tight binding simulations of the effect of an electric current on a mobile atom. The classical contribution to the ionic kinetic energy exhibits cooling and is independent of the bias. The quantum contribution exhibits strong heating, with the heating rate proportional to the bias. However, increased scattering of electrons with increasing ionic kinetic energy is not observed. This effect requires the introduction of the second moment
Strong and nonlinear effects of fragmentation on ecosystem service provision at multiple scales
Mitchell, Matthew G. E.; Bennett, Elena M.; Gonzalez, Andrew
2015-09-01
Human actions, such as converting natural land cover to agricultural or urban land, result in the loss and fragmentation of natural habitat, with important consequences for the provision of ecosystem services. Such habitat loss is especially important for services that are supplied by fragments of natural land cover and that depend on flows of organisms, matter, or people across the landscape to produce benefits, such as pollination, pest regulation, recreation and cultural services. However, our quantitative knowledge about precisely how different patterns of landscape fragmentation might affect the provision of these types of services is limited. We used a simple, spatially explicit model to evaluate the potential impact of natural land cover loss and fragmentation on the provision of hypothetical ecosystem services. Based on current literature, we assumed that fragments of natural land cover provide ecosystem services to the area surrounding them in a distance-dependent manner such that ecosystem service flow depended on proximity to fragments. We modeled seven different patterns of natural land cover loss across landscapes that varied in the overall level of landscape fragmentation. Our model predicts that natural land cover loss will have strong and unimodal effects on ecosystem service provision, with clear thresholds indicating rapid loss of service provision beyond critical levels of natural land cover loss. It also predicts the presence of a tradeoff between maximizing ecosystem service provision and conserving natural land cover, and a mismatch between ecosystem service provision at landscape versus finer spatial scales. Importantly, the pattern of landscape fragmentation mitigated or intensified these tradeoffs and mismatches. Our model suggests that managing patterns of natural land cover loss and fragmentation could help influence the provision of multiple ecosystem services and manage tradeoffs and synergies between services across different human
Effects of strong bite force on the facial vertical dimension of pembarong performers
Directory of Open Access Journals (Sweden)
C. Christina
2017-06-01
Full Text Available Background: A pembarong performer is a reog dancer who bites on a piece of wood inserted into his/her mouth in order to support a 60 kg Barongan or Dadak Merak mask. The teeth supporting this large and heavy mask are directly affected, as the strong bite force exerted during a dance could affect their vertical and sagital facial dimensions. Purpose: This study aimed to examine the influence of the bite force of pembarong performers due to their vertical and sagital facial dimensions. Methods: The study reported here involved fifteen pembarong performers and thirteen individuals with normal occlusion (with specific criteria. The bite force of these subjects was measured with a dental prescale sensor during its centric occlusion. A cephalometric variation measurement was subsequently performed on all subjects with its effects on their vertical and sagital facial dimensions being measured. Results: The bite force value of the pembarong performers was 394.3816 ± 7.68787 Newtons, while the normal occlusion was 371.7784 ± 4.77791 Newtons. There was no correlation between the bite force and the facial sagital dimension of these subjects. However, a significant correlation did exist between bite force and lower facial height/total facial height (LFH/TFH ratio (p = 0.013. Conversely, no significant correlation between bite force and posterior facial height/total facial height (PFH/TFH ratio (p = 0.785 was detected. There was an inverse correlation between bite force and LFH/TFH ratio (r = -.464. Conclusion: Bite force is directly related to the decrease in LFH/TFH ratio. Occlusal pressure exerted by the posterior teeth on the alveolar bone may increase bone density at the endosteal surface of cortical bone.
Park, Se Won; Ham, Ho Wan; Kim, Young Sik
2012-04-01
In the paper, we describe new Ir complexes for achieving efficient blue phosphorescence. New blue-emitting mixed-ligand Ir complexes comprising one cyclometalating, two phosphines trans to each other such as Ir(dppz)(PPh3)2(H)(L) (Ll= Cl, NCMe+, CN), [dppz = 3,5-Diphenylpyrazole] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To gain insight into the factors responsible for the emission color change and the variation of luminescence efficiency, we investigate the electron-withdrawing capabilities of ancillary ligands using DFT and TD-DFT calculations on the ground and excited states of the complexes. To achieve deep blue emission and increase the emission efficiency, (1) we substitute the phenyl group on the 3-position of the pyrazole ring that lowers the triplet energy enough that the quenching channel is not thermally accessible and (2) change the ancillary ligands coordinated to iridium atom to phosphine and cyano groups known as very strong field ligands. Their inclusion in the coordination sphere can increase the HOMO-LUMO gap to achieve the hypsochromic shift in emission color and lower the HOMO and LUMO energy level, which causes a large d-orbital energy splitting and avoids the quenching effect to improve the luminescence efficiency. The maximum emission spectra of Ir(dppz)(PPh3)2(H)(CI) and Ir(dppz)(PPh3)2(H)(CN) were in the ranges of 439, 432 nm, respectively.
The effect of dust charge inhomogeneity on low-frequency modes in a strongly coupled plasma
International Nuclear Information System (INIS)
Farid, T.; Mamun, A.A.; Shukla, P.K.
2000-01-01
An analysis of low-frequency modes accounting for dust grain charge fluctuation and equilibrium grain charge inhomogeneity in a strongly coupled dusty plasma is presented. The existence of an extremely low frequency mode, which is due to the inhomogeneity in the equilibrium dust grain charge, is reported. Besides, the equilibrium dust grain charge inhomogeneity makes the dust-acoustic mode unstable. The strong correlations in the dust fluid significantly drive a new mode as well as the existing dust-acoustic mode. The applications of these results to recent experimental and to some space and astrophysical situations are discussed
Non-adiabatic molecular dynamics with complex quantum trajectories. I. The diabatic representation.
Zamstein, Noa; Tannor, David J
2012-12-14
We extend a recently developed quantum trajectory method [Y. Goldfarb, I. Degani, and D. J. Tannor, J. Chem. Phys. 125, 231103 (2006)] to treat non-adiabatic transitions. Each trajectory evolves on a single surface according to Newton's laws with complex positions and momenta. The transfer of amplitude between surfaces stems naturally from the equations of motion, without the need for surface hopping. In this paper we derive the equations of motion and show results in the diabatic representation, which is rarely used in trajectory methods for calculating non-adiabatic dynamics. We apply our method to the first two benchmark models introduced by Tully [J. Chem. Phys. 93, 1061 (1990)]. Besides giving the probability branching ratios between the surfaces, the method also allows the reconstruction of the time-dependent wavepacket. Our results are in quantitative agreement with converged quantum mechanical calculations.
Development of a model for dimethyl ether non-adiabatic reactors to improve methanol conversion
Energy Technology Data Exchange (ETDEWEB)
Nasrollahi, Fatemeh [University of Tehran, Tehran (Iran, Islamic Republic of); Bakeri, Gholamreza; Rahimnejad, Mostafa [Babol Noshirvani University of Technology, Babol (Iran, Islamic Republic of); Ismail, Ahmad Fauzi [Universiti Teknologi Malaysia, Skudai (Malaysia); Imanian, Mahdi [Mohajer Technical University, Isfahan (Iran, Islamic Republic of)
2013-10-15
The modeling of adiabatic and non-adiabatic reactors, using three cooling mediums in the shell side of a shell and tube reactor in cocurrent and countercurrent flow regimes has been conducted. The cooling mediums used in this research are saturated water and methanol feed gas to a reactor which is preheated in the shell side and a special type of oil. The results of adiabatic reactor modeling show good compatibility with the data received from a commercial plant. The results of non-adiabatic reactor modeling showed that more methanol conversion can be achieved in a lower length of reactor, even though in some cases the maximum temperature in the tube side of the reactor is more than the deactivation temperature of the catalyst.
Energy Technology Data Exchange (ETDEWEB)
Warehime, Mick [Chemical Physics Program, University of Maryland, College Park, Maryland 20742-2021 (United States); Kłos, Jacek; Alexander, Millard H., E-mail: mha@umd.edu [Department of Chemistry and Biochemistry and Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021 (United States)
2015-01-21
This is the second in a series of papers detailing a MATLAB based implementation of the finite element method applied to collinear triatomic reactions. Here, we extend our previous work to reactions on coupled potential energy surfaces. The divergence of the probability current density field associated with the two electronically adiabatic states allows us to visualize in a novel way where and how nonadiabaticity occurs. A two-dimensional investigation gives additional insight into nonadiabaticity beyond standard one-dimensional models. We study the F({sup 2}P) + HCl and F({sup 2}P) + H{sub 2} reactions as model applications. Our publicly available code (http://www2.chem.umd.edu/groups/alexander/FEM) is general and easy to use.
Levitation of Bose-Einstein condensates induced by macroscopic non-adiabatic quantum tunneling
Nakamura, Katsuhiro; Kohi, Akihisa; Yamasaki, Hisatsugu; Perez-Garcia, Victor M.
2006-01-01
We study the dynamics of two-component Bose-Einstein condensates trapped in different vertical positions in the presence of an oscillating magnetic field. It is shown here how tuning appropriately the oscillation frequency of the magnetic field leads to the levitation of the system against gravity. This phenomenon is a manifestation of a macroscopic non-adiabatic tunneling in a system with internal degrees of freedom.
Tiwari, Vivek; Peters, William K.; Jonas, David M.
2017-10-01
Non-adiabatic vibrational-electronic resonance in the excited electronic states of natural photosynthetic antennas drastically alters the adiabatic framework, in which electronic energy transfer has been conventionally studied, and suggests the possibility of exploiting non-adiabatic dynamics for directed energy transfer. Here, a generalized dimer model incorporates asymmetries between pigments, coupling to the environment, and the doubly excited state relevant for nonlinear spectroscopy. For this generalized dimer model, the vibrational tuning vector that drives energy transfer is derived and connected to decoherence between singly excited states. A correlation vector is connected to decoherence between the ground state and the doubly excited state. Optical decoherence between the ground and singly excited states involves linear combinations of the correlation and tuning vectors. Excitonic coupling modifies the tuning vector. The correlation and tuning vectors are not always orthogonal, and both can be asymmetric under pigment exchange, which affects energy transfer. For equal pigment vibrational frequencies, the nonadiabatic tuning vector becomes an anti-correlated delocalized linear combination of intramolecular vibrations of the two pigments, and the nonadiabatic energy transfer dynamics become separable. With exchange symmetry, the correlation and tuning vectors become delocalized intramolecular vibrations that are symmetric and antisymmetric under pigment exchange. Diabatic criteria for vibrational-excitonic resonance demonstrate that anti-correlated vibrations increase the range and speed of vibronically resonant energy transfer (the Golden Rule rate is a factor of 2 faster). A partial trace analysis shows that vibronic decoherence for a vibrational-excitonic resonance between two excitons is slower than their purely excitonic decoherence.
Nonadiabatic Spin Torque Investigated Using Thermally Activated Magnetic Domain Wall Dynamics
DEFF Research Database (Denmark)
Eltschka, M.; Woetzel, Mathias; Rhensius, J.
2010-01-01
of the DW as a quasiparticle in a one-dimensional potential landscape. By injecting small currents, the potential is modified, allowing for the determination of the nonadiabatic spin torque: βt=0.010±0.004 for a transverse DW and βv=0.073±0.026 for a vortex DW. The larger value is attributed to the higher...
Strongly enhanced flow effect from Landau-Vlasov versus Vlasov-Uehling-Uhlenbeck approach
International Nuclear Information System (INIS)
Gregoire, C.; Remaud, B.; Sebille, F.; Schuck, P.
1988-01-01
The simulation of the collision integral in the Landau-Vlasov approach for heavy ion collisions is examined. It turns out that quantities like the nucleon mean free path can be compared with parallel ensemble models. Convergency of results with time step and sampling is clearly established. Quadratic quantities, like the internal pressure, are found to be strongly underestimated in parallel ensemble models
Research on the strong optical feedback effects based on spectral analysis method
Zeng, Zhaoli; Qu, XueMin; Li, Weina; Zhang, Min; Wang, Hao; Li, Tuo
2018-01-01
The strong optical feedback has the advantage of generating high resolution fringes. However, these feedback fringes usually seem like the noise signal when the feedback level is high. This defect severely limits its practical application. In this paper, the generation mechanism of noise fringes with strong optical feedback is studied by using spectral analysis method. The spectral analysis results show that, in most cases, the noise-like fringes are observed owing to the strong multiple high-order feedback. However, at certain feedback cavity condition, there may be only one high-order feedback beam goes back to the laser cavity, the noise-like fringes can change to the cosine-like fringes. And the resolution of this fringe is dozens times than that of the weak optical feedback. This research provides a method to obtain high resolution cosine-like fringes rather than noise signal in the strong optical feedback, which makes it possible to be used in nanoscale displacement measurements.
Communication: Strong excitonic and vibronic effects determine the optical properties of Li₂O₂
DEFF Research Database (Denmark)
García Lastra, Juan Maria; Bass, J. D.; Thygesen, Kristian Sommer
2011-01-01
The band structure and optical absorption spectrum of lithium peroxide (Li2O2) is calculated from first-principles using the G0W0 approximation and the Bethe-Salpeter equation, respectively. A strongly localized (Frenkel type) exciton corresponding to the π*→σ* transition on the O2 −2 peroxide ion...
Energy Technology Data Exchange (ETDEWEB)
Coïsson, M. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Barrera, G. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); University of Torino, Chemistry Department, via P. Giuria 7, 10125 Torino (Italy); Celegato, F.; Martino, L.; Vinai, F. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Martino, P. [Politronica srl, via Livorno 60, 10144 Torino (Italy); Ferraro, G. [Center for Space Human Robotics, Istituto Italiano di Tecnologia - IIT, corso Trento 21, 10129 Torino (Italy); Tiberto, P. [INRIM, strada delle Cacce 91, 10135 Torino (Italy)
2016-10-01
An experimental setup for magnetic hyperthermia operating in non-adiabatic conditions is described. A thermodynamic model that takes into account the heat exchanged by the sample with the surrounding environment is developed. A suitable calibration procedure is proposed that allows the experimental validation of the model. Specific absorption rate can then be accurately determined just from the measurement of the sample temperature at the equilibrium steady state. The setup and the measurement procedure represent a simplification with respect to other systems requiring calorimeters or crucial corrections for heat flow. Two families of magnetic nanoparticles, one superparamagnetic and one characterised by larger sizes and static hysteresis, have been characterised as a function of field intensity, and specific absorption rate and intrinsic loss power have been obtained. - Highlights: • Development and thermodynamic modelling of a hyperthermia setup operating in non-adiabatic conditions. • Calibration of the experimental setup and validation of the model. • Accurate measurement of specific absorption rate and intrinsic loss power in non-adiabatic conditions.
Trajectory-based nonadiabatic dynamics with time-dependent density functional theory.
Curchod, Basile F E; Rothlisberger, Ursula; Tavernelli, Ivano
2013-05-10
Understanding the fate of an electronically excited molecule constitutes an important task for theoretical chemistry, and practical implications range from the interpretation of atto- and femtosecond spectroscopy to the development of light-driven molecular machines, the control of photochemical reactions, and the possibility of capturing sunlight energy. However, many challenging conceptual and technical problems are involved in the description of these phenomena such as 1) the failure of the well-known Born-Oppenheimer approximation; 2) the need for accurate electronic properties such as potential energy surfaces, excited nuclear forces, or nonadiabatic coupling terms; and 3) the necessity of describing the dynamics of the photoexcited nuclear wavepacket. This review provides an overview of the current methods to address points 1) and 3) and shows how time-dependent density functional theory (TDDFT) and its linear-response extension can be used for point 2). First, the derivation of Ehrenfest dynamics and nonadiabatic Bohmian dynamics is discussed and linked to Tully's trajectory surface hopping. Second, the coupling of these trajectory-based nonadiabatic schemes with TDDFT is described in detail with special emphasis on the derivation of the required electronic structure properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Recent Advances and Perspectives on Nonadiabatic Mixed Quantum-Classical Dynamics.
Crespo-Otero, Rachel; Barbatti, Mario
2018-05-16
Nonadiabatic mixed quantum-classical (NA-MQC) dynamics methods form a class of computational theoretical approaches in quantum chemistry tailored to investigate the time evolution of nonadiabatic phenomena in molecules and supramolecular assemblies. NA-MQC is characterized by a partition of the molecular system into two subsystems: one to be treated quantum mechanically (usually but not restricted to electrons) and another to be dealt with classically (nuclei). The two subsystems are connected through nonadiabatic couplings terms to enforce self-consistency. A local approximation underlies the classical subsystem, implying that direct dynamics can be simulated, without needing precomputed potential energy surfaces. The NA-MQC split allows reducing computational costs, enabling the treatment of realistic molecular systems in diverse fields. Starting from the three most well-established methods-mean-field Ehrenfest, trajectory surface hopping, and multiple spawning-this review focuses on the NA-MQC dynamics methods and programs developed in the last 10 years. It stresses the relations between approaches and their domains of application. The electronic structure methods most commonly used together with NA-MQC dynamics are reviewed as well. The accuracy and precision of NA-MQC simulations are critically discussed, and general guidelines to choose an adequate method for each application are delivered.
Nonadiabatic excited-state molecular dynamics: On-the-fly limiting of essential excited states
Energy Technology Data Exchange (ETDEWEB)
Nelson, Tammie [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Naumov, Artem [Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Fernandez-Alberti, Sebastian [Universidad Nacional de Quilmes, Roque Saenz Pea 352, B1876BXD Bernal (Argentina); Tretiak, Sergei, E-mail: serg@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2016-12-20
The simulation of nonadiabatic dynamics in extended molecular systems involving hundreds of atoms and large densities of states is particularly challenging. Nonadiabatic coupling terms (NACTs) represent a significant numerical bottleneck in surface hopping approaches. Rather than using unreliable NACT cutting schemes, here we develop “on-the-fly” state limiting methods to eliminate states that are no longer essential for the non-radiative relaxation dynamics as a trajectory proceeds. We propose a state number criteria and an energy-based state limit. The latter is more physically relevant by requiring a user-imposed energy threshold. For this purpose, we introduce a local kinetic energy gauge by summing contributions from atoms within the spatial localization of the electronic wavefunction to define the energy available for upward hops. The proposed state limiting schemes are implemented within the nonadiabatic excited-state molecular dynamics framework to simulate photoinduced relaxation in poly-phenylene vinylene (PPV) and branched poly-phenylene ethynylene (PPE) oligomers for benchmark evaluation.
Coulomb effects on the transport properties of quantum dots in strong magnetic field
International Nuclear Information System (INIS)
Moldoveanu, V.; Aldea, A.; Manolescu, A.; Nita, M.
2000-08-01
We investigate the transport properties of quantum dots placed in strong magnetic field using a quantum-mechanical approach based on the 2D tight-binding Hamiltonian with direct Coulomb interaction and the Landauer-Buettiker (LB) formalism. The electronic transmittance and the Hall resistance show Coulomb oscillations and also prove multiple addition processes. We identify this feature as the 'bunching' of electrons observed in recent experiments and give an elementary explanation in terms of spectral characteristics of the dot. The spatial distribution of the added electrons may distinguish between edge and bulk states and it has specific features for bunched electrons. The dependence of the charging energy on the number of electrons is discussed for strong magnetic field. The crossover from the tunneling to quantum Hall regime is analyzed in terms of dot-lead coupling. (author)
Small Fermi energy, strong electron-phonon effects and anharmonicity in MgB2
International Nuclear Information System (INIS)
Cappelluti, E.; Pietronero, L.
2007-01-01
The investigation of the electron-phonon properties in MgB 2 has attracted a huge interest after the discovery of superconductivity with T c 39 K in this compound. Although superconductivity is often described in terms of the conventional Eliashberg theory, properly generalized in the multiband/multigap scenario, important features distinguish MgB 2 from other conventional strong-coupling superconductors. Most important it is the fact that a large part of the total electron-phonon strength seems to be concentrated here in only one phonon mode, the boron-boron E 2g stretching mode. Another interesting property is the small Fermi energy of the σ bands, which are strongly coupled with the E 2g mode. In this contribution, we discuss how the coexistence of both these features give rise to an unconventional phenomenology of the electron-phonon properties
Interference effects at photoionization of Rydberg atoms by a strong electromagnetic field
International Nuclear Information System (INIS)
Movsesyan, A.M.; Fedorov, M.V.
1989-01-01
The photoionization of Rydberg atoms in a strong electromagnetic field is considered. Degeneration of the levels with respect to the orbital moment, their Stark splitting and the possibility of resonant interaction with levels of lower energy are taken into account. The complex quasi-energies of the system, photoelectron spectrum in the limit of an infinite duration of interaction and the time dependence of the total ionization probability are found. It is shown that a narrowing of the quasi-energy levels occurs in a strong field. Against a background of the quasi- continuum the quasi-energy spectrum consists of more or less narrow levels. In this case the photoelectron spectrum acquires a multi-peak form. With increasing field strength the height of the peaks increases, whereas their width decreases. The ionization rate decreases with increasing field strength. The presence of a quasi-continuum is the cause of the partially non-exponential nature of the atomic disintegration
Effect of tilted anisotropy on spin states of strongly anisotropic 2D film
International Nuclear Information System (INIS)
Fridman, Yu. A.; Klevets, F. N.; Gorelikov, G. A.
2012-01-01
The spin states of a 2D film with a strong easy-plane anisotropy and single-ion tilted anisotropy, the axis of which forms a certain angle with the normal to the film plane are investigated. In this system, an angular ferromagnetic phase, a spatially inhomogeneous state, and a quadrupole phase can be formed; the realization of these states noticeably depends on the degree of tilted anisotropy.
Effects of strong cathodic polarization of the Ni-YSZ interface
DEFF Research Database (Denmark)
Hansen, Karin Vels; Chen, Ming; Jacobsen, Torben
2016-01-01
Long-term strong cathodic polarization experiments of down to -2.4 V vs. E°(O2) of the Ni-YSZ interface were performed at 900°C in 97% H2/3% H2O on model electrodes. The Ni-YSZ interface underwent extensive changes and a large affected volume with a complex microstructure and phase distribution r...
Enhanced magneto-plasmonic effect in Au/Co/Au multilayers caused by exciton–plasmon strong coupling
Energy Technology Data Exchange (ETDEWEB)
Hamidi, S.M., E-mail: m_hamidi@sbu.ac.ir; Ghaebi, O.
2016-09-15
In this paper, we have investigated magneto optical Kerr rotation using the strong coupling of exciton–plasmon. For this purpose, we have demonstrated strong coupling phenomenon using reflectometry measurements. These measurements revealed the formation of two split polaritonic extrema in reflectometry as a function of wavelength. Then we have shown exciton–plasmon coupling in dispersion diagram which presented an anti-crossing between the polaritonic branches. To assure the readers of strong coupling, we have shown an enhanced magneto-optical Kerr rotation by comparing the reflectometry results of strong coupling of surface Plasmon polariton of Au/Co/Au multilayer and R6G excitons with surface Plasmon polariton magneto-optical kerr effect experimental setup. - Highlights: • The magneto optical Kerr rotation has been investigated by using the strong coupling of exciton–plasmon. • We have shown exciton–plasmon coupling in dispersion diagram which presented an anti-crossing between the polaritonic branches. • Strong coupling of surface plasmon polariton and exciton have been yielded to the enhanced magneto-optical Kerr effect. • Plasmons in Au/Co/Au multilayer and exciton in R6G have been coupled to enhance magneto-optical activity.
Radiative transfer in a strongly magnetized plasma. I. Effects of Anisotropy
International Nuclear Information System (INIS)
Nagel, W.
1981-01-01
We present results of radiative transfer calculations for radiating slabs and columns of strongly magnetized plasma. The angular dependence of the escaping radiation was found numerically by Feautrier's method, using the differential scattering cross sections derived by Ventura. We also give an approximate analytical expression for the anisotropy of the outgoing radiation, based on a system of two coupled diffusion equations for ordinary and extraordinary photons. Giving the polarization dependence of the beaming pattern of radiating slabs as well as columns, we generalize previous results of Basko and Kanno. Some implications for models of the pulsating X-ray source Her X-1 are discussed
Atomic-structure effects in strong-field multiphoton detachment and ionization
International Nuclear Information System (INIS)
AAberg, T.; Mu, X.; Ruscheinski, J.; Crasemann, B.
1994-01-01
Above-threshold photoelectron detachment and ionization spectra are investigated theoretically in the tunneling and over-barrier regime as a function of wavelength (≥ 1.064 μm) and polarization of the electromagnetic field. It is found that the zeros in the initial-state wave function can drastically affect the shape of the high-energy photoelectron distribution. The phenomenon is not predicted by tunneling and related models and hence can test their validity and reveal whether Keldysh-type theories are in general applicable to strong-field multiphoton dynamics. (orig.)
Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.
2016-01-01
The dispersion properties of low frequency dust acoustic waves in the strong coupling regime are investigated experimentally in an argon plasma embedded with a mixture of kaolin and $MnO_2$ dust particles. The neutral pressure is varied over a wide range to change the collisional properties of the dusty plasma. In the low collisional regime the turnover of the dispersion curve at higher wave numbers and the resultant region of $\\partial\\omega/\\partial k < 0$ are identified as signatures of du...
Energy Technology Data Exchange (ETDEWEB)
Chung, D H; Bernreuter, D L
1981-10-01
Attenuation is caused by geometric spreading and absorption. Geometric spreading is almost independent of crustal geology and physiographic region, but absorption depends strongly on crustal geology and the state of the earth's upper mantle. Except for very high frequency waves, absorption does not affect ground motion at distances less than about 25 to 50 km. Thus, in the near-field zone, the attenuation in the eastern United States is similar to that in the western United States. Beyond the near field, differences in ground motion can best be accounted for by differences in attenuation caused by differences in absorption. The stress drop of eastern earthquakes may be higher than for western earthquakes of the same seismic moment, which would affect the high-frequency spectral content. But we believe this factor is of much less significance than differences in absorption in explaining the differences in ground motion between the East and the West. The characteristics of strong ground motion in the conterminous United States are discussed in light of these considerations, and estimates are made of the epicentral ground motions in the central and eastern United States. (author)
Stability in a fiber bundle model: Existence of strong links and the effect of disorder
Roy, Subhadeep
2018-05-01
The present paper deals with a fiber bundle model which consists of a fraction α of infinitely strong fibers. The inclusion of such an unbreakable fraction has been proven to affect the failure process in early studies, especially around a critical value αc. The present work has a twofold purpose: (i) a study of failure abruptness, mainly the brittle to quasibrittle transition point with varying α and (ii) variation of αc as we change the strength of disorder introduced in the model. The brittle to quasibrittle transition is confirmed from the failure abruptness. On the other hand, the αc is obtained from the knowledge of failure abruptness as well as the statistics of avalanches. It is observed that the brittle to quasibrittle transition point scales to lower values, suggesting more quasi-brittle-like continuous failure when α is increased. At the same time, the bundle becomes stronger as there are larger numbers of strong links to support the external stress. High α in a highly disordered bundle leads to an ideal situation where the bundle strength, as well as the predictability in failure process is very high. Also, the critical fraction αc, required to make the model deviate from the conventional results, increases with decreasing strength of disorder. The analytical expression for αc shows good agreement with the numerical results. Finally, the findings in the paper are compared with previous results and real-life applications of composite materials.
The mechanism of strong electric field effect on the dispersed media in the rarefied gas
International Nuclear Information System (INIS)
Gagarin, A.G.; Savchenko, Y.N.; Vigdonchik, V.H.
1985-01-01
This paper discusses two approaches to the description of the flow of fluids and gases, that is, a phenomenological method and a molecular-kinetic method. Four dispersed admixtures are described using the model of solid spheres as for molecules and a system of aerodynamic equations is obtained. In this system interactions between gas molecules and admixtures are taken into consideration already in the zero approximation. The paper is also concerned with the experimental study of the motion of dispersed particles in corona discharge which is a typical example of a strong nonuniform electric field with a volume discharge. From the comparison of experimental and calculated paths it was found that the particles move five to seven times faster than they would have done under the action of the Coulomb force alone at a real amount of charge of the particle. The result of comparison also shows that their motion primarily depends on the jet flow of electric wind
Strongly luminescent monolayered MoS2 prepared by effective ultrasound exfoliation.
Štengl, Václav; Henych, Jiří
2013-04-21
Intense ultrasound in a pressurized batch reactor was used for preparation of monolayered MoS2 nanosheets from natural mineral molybdenite. Exfoliation of bulk MoS2 using ultrasound is an attractive route to large-scale preparation of monolayered crystals. To evaluate the quality of delamination, methods like X-ray diffraction, Raman spectroscopy and microscopic techniques (TEM and AFM) were employed. From single- or few-layered products obtained from intense sonication, MoS2 quantum dots (MoSQDs) were prepared by a one-pot reaction by refluxing exfoliated nanosheets of MoS2 in ethylene glycol under atmospheric pressure. The synthesised MoSQDs were characterised by photoluminescence spectroscopy and laser-scattering particle size analysis. Our easy preparation leads to very strongly green luminescing quantum dots.
DEFF Research Database (Denmark)
Katajainen, Jyrki
2008-01-01
In this project the goal is to develop the safe * family of containers for the CPH STL. The containers to be developed should be safer and more reliable than any of the existing implementations. A special focus should be put on strong exception safety since none of the existing prototypes available...
Lahiri, B. B.; Ranoo, Surojit; Philip, John
2017-11-01
Magnetic fluid hyperthermia (MFH) is becoming a viable cancer treatment methodology where the alternating magnetic field induced heating of magnetic fluid is utilized for ablating the cancerous cells or making them more susceptible to the conventional treatments. The heating efficiency in MFH is quantified in terms of specific absorption rate (SAR), which is defined as the heating power generated per unit mass. In majority of the experimental studies, SAR is evaluated from the temperature rise curves, obtained under non-adiabatic experimental conditions, which is prone to various thermodynamic uncertainties. A proper understanding of the experimental uncertainties and its remedies is a prerequisite for obtaining accurate and reproducible SAR. Here, we study the thermodynamic uncertainties associated with peripheral heating, delayed heating, heat loss from the sample and spatial variation in the temperature profile within the sample. Using first order approximations, an adiabatic reconstruction protocol for the measured temperature rise curves is developed for SAR estimation, which is found to be in good agreement with those obtained from the computationally intense slope corrected method. Our experimental findings clearly show that the peripheral and delayed heating are due to radiation heat transfer from the heating coils and slower response time of the sensor, respectively. Our results suggest that the peripheral heating is linearly proportional to the sample area to volume ratio and coil temperature. It is also observed that peripheral heating decreases in presence of a non-magnetic insulating shielding. The delayed heating is found to contribute up to ~25% uncertainties in SAR values. As the SAR values are very sensitive to the initial slope determination method, explicit mention of the range of linear regression analysis is appropriate to reproduce the results. The effect of sample volume to area ratio on linear heat loss rate is systematically studied and the
International Nuclear Information System (INIS)
Lahiri, B B; Ranoo, Surojit; Philip, John
2017-01-01
Magnetic fluid hyperthermia (MFH) is becoming a viable cancer treatment methodology where the alternating magnetic field induced heating of magnetic fluid is utilized for ablating the cancerous cells or making them more susceptible to the conventional treatments. The heating efficiency in MFH is quantified in terms of specific absorption rate (SAR), which is defined as the heating power generated per unit mass. In majority of the experimental studies, SAR is evaluated from the temperature rise curves, obtained under non-adiabatic experimental conditions, which is prone to various thermodynamic uncertainties. A proper understanding of the experimental uncertainties and its remedies is a prerequisite for obtaining accurate and reproducible SAR. Here, we study the thermodynamic uncertainties associated with peripheral heating, delayed heating, heat loss from the sample and spatial variation in the temperature profile within the sample. Using first order approximations, an adiabatic reconstruction protocol for the measured temperature rise curves is developed for SAR estimation, which is found to be in good agreement with those obtained from the computationally intense slope corrected method. Our experimental findings clearly show that the peripheral and delayed heating are due to radiation heat transfer from the heating coils and slower response time of the sensor, respectively. Our results suggest that the peripheral heating is linearly proportional to the sample area to volume ratio and coil temperature. It is also observed that peripheral heating decreases in presence of a non-magnetic insulating shielding. The delayed heating is found to contribute up to ∼25% uncertainties in SAR values. As the SAR values are very sensitive to the initial slope determination method, explicit mention of the range of linear regression analysis is appropriate to reproduce the results. The effect of sample volume to area ratio on linear heat loss rate is systematically studied and
International Nuclear Information System (INIS)
Froissart, Marcel
1976-01-01
Strong interactions are introduced by their more obvious aspect: nuclear forces. In hadron family, the nucleon octet, OMEGA - decuplet, and quark triply are successively considered. Pion wave having been put at the origin of nuclear forces, low energy phenomena are described, the force being explained as an exchange of structure corresponding to a Regge trajectory in a variable rotating state instead of the exchange of a well defined particle. At high energies the concepts of pomeron, parton and stratons are introduced, pionization and fragmentation are briefly differentiated [fr
Pretreatment with divided doses of steroids strongly decreases side effects of OKT3
Bemelman, F. J.; Buysmann, S.; Surachno, J.; Wilmink, J. M.; Schellekens, P. T.; ten Berge, I. J.
1994-01-01
The aim of this study was to attenuate side effects of OKT3 by variation of the time interval between administration of corticosteroids and OKT3 in renal allograft recipients. In view of a maximal lymphocytopenia at six hours following MPNS, we postulated a greater preventive action on side effects
International Nuclear Information System (INIS)
Stevenson, J.D.
1995-11-01
Volume 2 of the ''Survey of Strong Motion Earthquake Effects on Thermal Power Plants in California with Emphasis on Piping Systems'' contains Appendices which detail the detail design and seismic response of several power plants subjected to strong motion earthquakes. The particular plants considered include the Ormond Beach, Long Beach and Seal Beach, Burbank, El Centro, Glendale, Humboldt Bay, Kem Valley, Pasadena and Valley power plants. Included is a typical power plant piping specification and photographs of typical power plant piping specification and photographs of typical piping and support installations for the plants surveyed. Detailed piping support spacing data are also included
International Nuclear Information System (INIS)
Bobrov, V.B.; Triger, S.A.
1994-01-01
The effective collision frequency method developed earlier by the authors for Coulomb systems characterized by strong interion interaction is developed further. An explicit expression is obtained for the effective electron collision frequency on the basis of the exact diagram representation obtained in Part I and the use of the model of a one-component plasma as initial approximation. The description of plasma structure in the corresponding approximation is considered. 25 refs
Electrical transverse transport in Lorentz plasma with strong magnetic field and collision effect
International Nuclear Information System (INIS)
Xie, Baisong; Chong, L.V.; Li, Ziliang
2015-01-01
In inertial confinement fusion (ICF), the spontaneous magnetic field formed from laser interacting with the pellet may reach few hundreds of Megagauss (MG) which results in the cyclotron frequency ω at the same order of the collision frequency υ. Electrical transverse transport in this case would become very important so that we study it by the Boltzmann equation for different electron density distribution. For the Maxwell distribution, it is shown that transport coefficients decrease with the increase of Ω (the ratio of ω to υ), which means the electrons would be highly collimated by strong magnetic field. This is attributed to that the electron's gyroradius is smaller than the collisional mean free paths. Moreover, the electrical transverse transport is also studied for quasi-monoenergy distribution with different width ε, which is different from the Maxwell one. It is found that the transport coefficients decrease greatly as quasi-monoenergy degree increases. In particular when ε approaches to zero, i.e. the Delta distribution with almost perfect monoenergy electron density, the electric conductivity doesn't change while the thermal conductivity decreases with Ω. On the other hand the smaller the ε is the less amount the transverse transport exhibits. Our study indicates that they are beneficial to limit the electric transverse transport. (author)
Groot, Maartje P; Kubisch, Alexander; Ouborg, N Joop; Pagel, Jörn; Schmid, Karl J; Vergeer, Philippine; Lampei, Christian
2017-08-01
Transgenerational environmental effects can trigger strong phenotypic variation. However, it is unclear how cues from different preceding generations interact. Also, little is known about the genetic variation for these life history traits. Here, we present the effects of grandparental and parental mild heat, and their combination, on four traits of the third-generation phenotype of 14 Arabidopsis thaliana genotypes. We tested for correlations of these effects with climate and constructed a conceptual model to identify the environmental conditions that favour the parental effect on flowering time. We observed strong evidence for genotype-specific transgenerational effects. On average, A. thaliana accustomed to mild heat produced more seeds after two generations. Parental effects overruled grandparental effects in all traits except reproductive biomass. Flowering was generally accelerated by all transgenerational effects. Notably, the parental effect triggered earliest flowering in genotypes adapted to dry summers. Accordingly, this parental effect was favoured in the model when early summer heat terminated the growing season and environments were correlated across generations. Our results suggest that A. thaliana can partly accustom to mild heat over two generations and genotype-specific parental effects show non-random evolutionary divergence across populations that may support climate change adaptation in the Mediterranean. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
The effect of whole body irradiation on the action of strong analgesics of mice
International Nuclear Information System (INIS)
Cvetkovicj, M.; Milovanovicj, A.; Tanasijevicj, D.
1987-01-01
The effect of whole body irradiation of male mice with single doses of 3 and 7 Gy ( 60 Co source) on analgesic action of three morphine-like drugs was studied. Over the first 6 days after irradiation, the analgesic effect of alfentanil and fentanyl was significantly less pronounced in irradiated animals than in control ones. During the subsequent period of 24 days till the end of experiment, the analgesic effect in irradiated animals gradually increased reaching and exceeding the control values. On the contrary, the analgesic effect of butorphanole was less pronounced in irradiated animals than in control ones, although the difference was not significantly. The difference between butorphanole and other two drugs are probably due to chemical structure and the metabolic fate in the body. (author) 8 refs.; 2 figs
International Nuclear Information System (INIS)
Galilo, Bogdan V.; Nedelko, Sergei N.
2011-01-01
The one-loop quark contribution to the QCD effective potential for the homogeneous Abelian gluon field in the presence of an external strong electromagnetic field is evaluated. The structure of extrema of the potential as a function of the angles between chromoelectric, chromomagnetic, and electromagnetic fields is analyzed. In this setup, the electromagnetic field is considered as an external one while the gluon field represents domain structured nonperturbative gluon configurations related to the QCD vacuum in the confinement phase. Two particularly interesting gluon configurations, (anti-)self-dual and crossed orthogonal chromomagnetic and chromoelectric fields, are discussed specifically. Within this simplified framework it is shown that the strong electromagnetic fields can play a catalyzing role for a deconfinement transition. At the qualitative level, the present consideration can be seen as a highly simplified study of an impact of the electromagnetic fields generated in relativistic heavy ion collisions on the strongly interacting hadronic matter.
Zhang, C.; Feng, T.; Raabe, N.; Rottke, H.
2018-02-01
Strong-field ionization (SFI) of the homonuclear noble gas dimer Xe2 is investigated and compared with SFI of the Xe atom and of the ArXe heteronuclear dimer by using ultrashort Ti:sapphire laser pulses and photoelectron momentum spectroscopy. The large separation of the two nuclei of the dimer allows the study of two-equivalent-center interference effects on the photoelectron momentum distribution. Comparing the experimental results with a new model calculation, which is based on the strong-field approximation, actually reveals the influence of interference. Moreover, the comparison indicates that the presence of closely spaced gerade and ungerade electronic state pairs of the Xe2 + ion at the Xe2 ionization threshold, which are strongly dipole coupled, affects the photoelectron momentum distribution.
Perspective has a strong effect on the calculation of historical contributions to global warming
Skeie, Ragnhild B.; Fuglestvedt, Jan; Berntsen, Terje; Peters, Glen P.; Andrew, Robbie; Allen, Myles; Kallbekken, Steffen
2017-02-01
The politically contentious issue of calculating countries’ contributions to climate change is strongly dependent on methodological choices. Different principles can be applied for distributing efforts for reducing human-induced global warming. According to the ‘Brazilian Proposal’, industrialized countries would reduce emissions proportional to their historical contributions to warming. This proposal was based on the assumption that the political process would lead to a global top-down agreement. The Paris Agreement changed the role of historical responsibilities. Whereas the agreement refers to equity principles, differentiation of mitigation efforts is delegated to each country, as countries will submit new national contributions every five years without any international negotiation. It is likely that considerations of historical contributions and distributive fairness will continue to play a key role, but increasingly so in a national setting. Contributions to warming can be used as a background for negotiations to inform and justify positions, and may also be useful for countries’ own assessment of what constitutes reasonable and fair contributions to limiting warming. Despite the fact that the decision from COP21 explicitly rules out compensation in the context of loss and damage, it is likely that considerations of historical responsibility will also play a role in future discussions. However, methodological choices have substantial impacts on calculated contributions to warming, including rank-ordering of contributions, and thus support the view that there is no single correct answer to the question of how much each country has contributed. There are fundamental value-related and ethical questions that cannot be answered through a single set of calculated contributions. Thus, analyses of historical contributions should not present just one set of results, but rather present a spectrum of results showing how the calculated contributions vary with a
Effects of a parental program for preventing underage drinking - The NGO program strong and clear
Directory of Open Access Journals (Sweden)
Eriksson Charli
2011-04-01
Full Text Available Abstract Background The present study is an evaluation of a 3-year parental program aiming to prevent underage drinking. The intervention was implemented by a non-governmental organization and targeted parents with children aged 13-16 years old and included recurrent activities during the entire period of secondary school. The program consisted of four different types of group and self-administered activities: parent meetings, family dialogues, friend meetings, and family meetings. Methods A quasi-experimental design was used following parents and children with questionnaires during the three years of secondary school. The analytic sample consisted of 509 dyads of parents and children. Measures of parental attitudes and behaviour concerning underage drinking and adolescents' lifetime alcohol consumption and drunkenness were used. Three socio-demographic factors were included: parental education, school, and gender of the child. A Latent Growth Modelling (LGM approach was used to examine changes in parental behaviour regarding youth drinking and in young people's drinking behaviour. To test for the pre-post test differences in parental attitudes repeated measures ANOVA were used. Results The results showed that parents in the program maintained their restrictive attitude toward underage drinking to a higher degree than non-participating parents. Adolescents of participants were on average one year older than adolescents with non-participating parents when they made their alcohol debut. They were also less likely to have ever been drunk in school year 9. Conclusion The results of the study suggested that Strong and Clear contributed to maintaining parents' restrictive attitude toward underage drinking during secondary school, postponing alcohol debut among the adolescents, and significantly reducing their drunkenness.
Strong ligand field effects of blue phosphorescent mono-cyclometalated iridium(III) complexes
International Nuclear Information System (INIS)
Ham, Ho Wan; Jung, Kyung Yoon; Kim, Young Sik
2010-01-01
A series of mono-cyclometalated blue phosphorescent iridium(III) complexes with two phosphines trans to each other and two cis-ancillary ligands, such as Ir(F 2 Meppy)(PPhMe 2 ) 2 (H)(Cl), [Ir(F 2 Meppy)(PPhMe 2 ) 2 (H)(NCMe)] + and Ir(F 2 Meppy)(PPhMe 2 ) 2 -(H)(CN), [F 2 Meppy = 2-(2',4'-difluorophenyl)-4-methyl-pyridine] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. We investigate the electron-withdrawing capabilities of ancillary ligands using the DFT and TD-DFT calculations on the ground and excited states of the three complexes to gain insight into the factors responsible for the emission color change and the different luminescence efficiency. Reducing the molecular weight of phosphine ligand with PPhMe 2 leads to a strategy of the efficient deep blue organic light-emitting devices (OLED) by thermal processing instead of the solution processing. The electron-withdrawing difluoro group substituted on the phenyl ring and the cyano strong field ancillary ligand in the trans position to the carbon atom of phenyl ring increased HOMO-LUMO gap and achieved the hypsochromic shift in emission color. As a result, the maximum emission spectra of Ir(F 2 Meppy)(PPhMe 2 ) 2 (H)(Cl), [Ir(F 2 Meppy)(PPhMe 2 ) 2 (H)-(NCMe)] + and Ir(F 2 Meppy)(PPh-Me 2 ) 2 (H)(CN) were in the ranges of 446, 440, 439 nm, respectively.
Strong ligand field effects of blue phosphorescent mono-cyclometalated iridium(III) complexes
Energy Technology Data Exchange (ETDEWEB)
Ham, Ho Wan [Department of Information Display, Hongik University, Seoul, 121-791 (Korea, Republic of); Jung, Kyung Yoon [International Design School for Advanced Studies, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Young Sik, E-mail: youngkim@hongik.ac.k [Department of Information Display, Hongik University, Seoul, 121-791 (Korea, Republic of)
2010-09-01
A series of mono-cyclometalated blue phosphorescent iridium(III) complexes with two phosphines trans to each other and two cis-ancillary ligands, such as Ir(F{sub 2}Meppy)(PPhMe{sub 2}){sub 2}(H)(Cl), [Ir(F{sub 2}Meppy)(PPhMe{sub 2}){sub 2}(H)(NCMe)]{sup +} and Ir(F{sub 2}Meppy)(PPhMe{sub 2}){sub 2}-(H)(CN), [F{sub 2}Meppy = 2-(2',4'-difluorophenyl)-4-methyl-pyridine] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. We investigate the electron-withdrawing capabilities of ancillary ligands using the DFT and TD-DFT calculations on the ground and excited states of the three complexes to gain insight into the factors responsible for the emission color change and the different luminescence efficiency. Reducing the molecular weight of phosphine ligand with PPhMe{sub 2} leads to a strategy of the efficient deep blue organic light-emitting devices (OLED) by thermal processing instead of the solution processing. The electron-withdrawing difluoro group substituted on the phenyl ring and the cyano strong field ancillary ligand in the trans position to the carbon atom of phenyl ring increased HOMO-LUMO gap and achieved the hypsochromic shift in emission color. As a result, the maximum emission spectra of Ir(F{sub 2}Meppy)(PPhMe{sub 2}){sub 2}(H)(Cl), [Ir(F{sub 2}Meppy)(PPhMe{sub 2}){sub 2}(H)-(NCMe)]{sup +} and Ir(F{sub 2}Meppy)(PPh-Me{sub 2}){sub 2} (H)(CN) were in the ranges of 446, 440, 439 nm, respectively.
Strong synergistic effects in PLA/PCL blends: Impact of PLA matrix viscosity.
Ostafinska, Aleksandra; Fortelný, Ivan; Hodan, Jiří; Krejčíková, Sabina; Nevoralová, Martina; Kredatusová, Jana; Kruliš, Zdeněk; Kotek, Jiří; Šlouf, Miroslav
2017-05-01
Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.
How strong is the edge effect in the adsorption of anticancer drugs on a graphene cluster?
Rungnim, Chompoonut; Chanajaree, Rungroj; Rungrotmongkol, Thanyada; Hannongbua, Supot; Kungwan, Nawee; Wolschann, Peter; Karpfen, Alfred; Parasuk, Vudhichai
2016-04-01
The adsorption of nucleobase-analog anticancer drugs (fluorouracil, thioguanine, and mercaptopurine) on a graphene flake (C54H18) was investigated by shifting the site at which adsorption occurs from one end of the sheet to the other end. The counterpoise-corrected M06-2X/cc-pVDZ binding energies revealed that the binding stability decreases in the sequence thioguanine > mercaptopurine > fluorouracil. We found that adsorption near the middle of the sheet is more favorable than adsorption near the edge due to the edge effect. This edge effect is stronger for the adsorption of thioguanine or mercaptopurine than for fluorouracil adsorption. However, the edge effect reduces the binding energy of the drug to the flake by only a small amount, <5 kcal/mol, depending on the adsorption site and the alignment of the drug at this site.
International Nuclear Information System (INIS)
Song, Mi-Young; Jung, Young-Dae
2003-01-01
Quantum screening effects on the occurrence scattering time advance for elastic electron-ion collisions in strongly coupled semiclassical plasmas are investigated using the second-order eikonal analysis. The electron-ion interaction in strongly coupled semiclassical plasmas is obtained by the pseudopotential model taking into account the plasma screening and quantum effects. It is found that the quantum-mechanical effects significantly reduce the occurrence scattering time advance. It is also found that the occurrence scattering time advance increases with increasing Debye length. It is quite interesting to note that the domain of the maximum occurrence time advance is localized for the forward scattering case. The region of the scaled thermal de Broglie wave length (λ-bar) for the maximum occurrence time advance is found to be 0.4≤λ-bar≤1.4
Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo.
Lehmann, Kai S; Poch, Franz G M; Rieder, Christian; Schenk, Andrea; Stroux, Andrea; Frericks, Bernd B; Gemeinhardt, Ole; Holmer, Christoph; Kreis, Martin E; Ritz, Jörg P; Zurbuchen, Urte
2016-08-01
The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels. © 2016 Japanese Society of Hepato-Biliary-Pancreatic Surgery.
PAH effects on meio- and microbial benthic communities strongly depend on bioavailability.
Lindgren, J Fredrik; Hassellöv, Ida-Maja; Dahllöf, Ingela
2014-01-01
The effects of anthropogenic pollutants in dissimilar habitats can vary depending on differences in bioavailability. The factors determining bioavailability are not yet fully understood. This study was performed to evaluate whether analysis of total PAH concentrations in sediments is a satisfactory measurement to indicate environmental effects or if bioavailability is needed to be taken into account. We have here performed a 60-day experiment, where nominal PAH concentrations of 1,300 μg/kg sediment were added to three different marine sediments. Meiofaunal and microbial communities were analyzed for alterations in community response at 30 and 60 days. Results showed that bioavailability of PAHs varied between the three different sediments. Nonetheless, the petroleum addition gave rise to significant negative effects on all three sediments at both time points. The two direct measurements of toxicity on the microbial community, potential nitrification and denitrification, displayed a lower effect of the PAH addition in the muddy sediment at both time points, compared to the other two sediment types. No effects were seen in the analysis of meiofaunal community structure. Measurements of PAH bioavailability in the three sediment types concurred with the results from the microbial community, revealing a lower bioavailability in the muddy sediment compared to the other two sediment types, 34% compared to sandy and 18% compared to organic at day 0. At day 60 it was 61% lower compared to sandy and 20% lower compared to organic. The negative effects of the PAH addition on the microbial nitrogen cycle were in six out of eight cases best correlated to the amount of alkylated bioavailable PAH in the sediments, and thus microbial nitrogen cycle is a possible good indicator for assessing PAH-induced stress. The results presented here have implications for risk analysis studies of petroleum-contaminated marine sediments; consequently, sediment characteristics and its effects on
Propagation and diffusion-limited extinction of nonadiabatic heterogeneous flame in the SHS process
International Nuclear Information System (INIS)
Makino, Atsushi
1994-01-01
Nonadiabatic heterogeneous flame propagation and extinction in self-propagating high-temperature synthesis (SHS) are analyzed based on a premixed mode of propagation for the bulk flame supported by the nonpremixed reaction of dispersed nonmetals in the liquid metal. The formulation allows for volumetric heat loss throughout the bulk flame, finite-rate Arrhenius reaction at the particle surface, and temperature-sensitive Arrhenius mass diffusion in the liquid. Results show that, subsequent to melting of the metal, the flame structure consists of a relatively thin diffusion-consumption/convection zone followed by a relatively thick convection-loss zone, that the flame propagation rate decreases with increasing heat loss, that at a critical heat-loss rate the flame extinguishes as indicated by the characteristic turning-point behavior, that the surface reaction is diffusion limited such that the nonlinear, temperature-sensitive nature of the system is actually a consequence of the Arrhenius mass diffusion, and that extinction is sensitively affected by the mixture ratio, the degree of dilution, the initial temperature of the compact, and the size of the nonmetal particles. An explicit expression is derived for the normalized mass burning rate, which exhibits the characteristic turning point and shows that extinction occurs when this value is reduced to e -1/2 , which is the same as that for the nonadiabatic gaseous premixed flame. It is further shown that the theoretical results agree well with available experimental data, indicating that the present formulation captures the essential features of the nonadiabatic heterogeneous SHS processes and its potential for extension to describe other SHS phenomena
Effect of strong electrolytes on edible oils part II: vViscosity of maize ...
African Journals Online (AJOL)
The electrolytes behave as structure breaker. The effect of temperature was also determined in terms of fluidity parameters, energy of activation, latent heat of vaporization, molar volume of oil and free energy change of activation for viscous flow. Journal of Applied Sciences and Environmental Management Vol. 10 (3) 2006: ...
Strong and long: effects of word length on phonological binding in verbal short-term memory.
Jefferies, Elizabeth; Frankish, Clive; Noble, Katie
2011-02-01
This study examined the effects of item length on the contribution of linguistic knowledge to immediate serial recall (ISR). Long words are typically recalled more poorly than short words, reflecting the greater demands that they place on phonological encoding, rehearsal, and production. However, reverse word length effects--that is, better recall of long than short words--can also occur in situations in which phonological maintenance is difficult, suggesting that long words derive greater support from long-term lexical knowledge. In this study, long and short words and nonwords (containing one vs. three syllables) were presented for immediate serial recall in (a) pure lists and (b) unpredictable mixed lists of words and nonwords. The mixed-list paradigm is known to disrupt the phonological stability of words, encouraging their phonemes to recombine with the elements of other list items. In this situation, standard length effects were seen for nonwords, while length effects for words were absent or reversed. A detailed error analysis revealed that long words were more robust to the mixed-list manipulation than short words: Their phonemes were less likely to be omitted and to recombine with phonemes from other list items. These findings support an interactive view of short-term memory, in which long words derive greater benefits from lexical knowledge than short words-especially when their phonological integrity is challenged by the inclusion of nonwords in mixed lists.
Luo, Jun-Wei; Li, Shu-Shen; Zunger, Alex
2017-09-01
The electric field manipulation of the Rashba spin-orbit coupling effects provides a route to electrically control spins, constituting the foundation of the field of semiconductor spintronics. In general, the strength of the Rashba effects depends linearly on the applied electric field and is significant only for heavy-atom materials with large intrinsic spin-orbit interaction under high electric fields. Here, we illustrate in 1D semiconductor nanowires an anomalous field dependence of the hole (but not electron) Rashba effect (HRE). (i) At low fields, the strength of the HRE exhibits a steep increase with the field so that even low fields can be used for device switching. (ii) At higher fields, the HRE undergoes a rapid transition to saturation with a giant strength even for light-atom materials such as Si (exceeding 100 meV Å). (iii) The nanowire-size dependence of the saturation HRE is rather weak for light-atom Si, so size fluctuations would have a limited effect; this is a key requirement for scalability of Rashba-field-based spintronic devices. These three features offer Si nanowires as a promising platform for the realization of scalable complementary metal-oxide-semiconductor compatible spintronic devices.
Effect of inter-fibre bonding on the fracture of fibrous networks with strong interactions
DEFF Research Database (Denmark)
Goutianos, Stergios; Mao, Rui; Peijs, Ton
2017-01-01
Abstract The mechanical response of cellulose nanopaper composites is investigated using a three-dimensional (3D) finite element fibrous network model with focus on the effect of inter-fibre bonds. It is found that the Young’s modulus and strength, for fixed fibre properties, are mainly controlle...
Effect of strong-focusing field distortions on particle motion in a linear accelerator
International Nuclear Information System (INIS)
Bondarev, B.I.; Durkin, A.P.; Solov'ev, L.Yu.
1979-01-01
The increased sensitivity of quadrupole focusing channel used in the highenergetic part of the linear accelerator makes it necessary to pay serious attention to the effect of various distortions of focusing fields on the transverse motion of the beam. The distortions may cause the inadmissible losses of particles in the accelerator. To achieve this aim the main equation of disturbed motion of particles in the linear accelerator, obtained by analogy with the cyclic accelerator theory is presented. The investigation of the solutions of this equation has permitted to obtain the analytical formulas for the estimation of the beam size increase under the effect of focusing field distortions of various types, such as structural non-linearity, gradient errors, random non-linearity, channel axis deformation. While studying the effect of structural non-linearity considered are the resonance effects and obtained are the relations describing the maximum beam size increase in the channel of the linear accelerator in the presence and in the absence of the resonance
Faraday effect in rare-earth ferrite garnets located in strong magnetic fields
International Nuclear Information System (INIS)
Valiev, U.V.; Zvezdin, A.K.; Krinchik, G.S.; Levitin, R.Z.; Mukimov, K.M.; Popov, A.I.
1983-01-01
The Faraday effect is investigated experimentally in single crystal specimens of rare earth iron garnets (REIG) R 3 Fe 5 O 12 (R=Y, Gd, Tb, Dy, Er, Tm, Yb, Eu, Sm and Ho) and also in mixed iron garnets Rsub(x)Ysub(3-x)Fesub(5)Osub(12) (R=Tb, Dy). The m.easurements are carried out in pulsed magnetic fields of intensity up to 200 kOe, in a temperature range from 4.2 to 300 K and at a wavelength of the light lambda=1.15 μm. The field dependence of the Faraday effect observed in the REIG cannot be explained if only the usually considered ''paramagnetic'' contribution to the Faraday effect is taken into account. A theory is developed which, besides the paramagnetic mechanism, takes into account a diamagnetic mechanism and also the mixing of the wave functions of the ground and excited multiplets. The contributions of each of these three mechanisms to the angle of rotation of the plane of polarization by the rare earth sublattice of the iron garnet are estimated theoretically. It is concluded that the mixing mechanism contributes significantly to the field and temperature dependences of the Faraday effect in REIG
Wang, Yu; Chou, Chia-Chun
2018-05-01
The coupled complex quantum Hamilton-Jacobi equations for electronic nonadiabatic transitions are approximately solved by propagating individual quantum trajectories in real space. Equations of motion are derived through use of the derivative propagation method for the complex actions and their spatial derivatives for wave packets moving on each of the coupled electronic potential surfaces. These equations for two surfaces are converted into the moving frame with the same grid point velocities. Excellent wave functions can be obtained by making use of the superposition principle even when nodes develop in wave packet scattering.
Energy Technology Data Exchange (ETDEWEB)
Leys, Jan; Glorieux, Christ; Thoen, Jan [Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D-bus 2416, B-3001 Leuven (Belgium)], E-mail: jan.leys@fys.kuleuven.be, E-mail: jan.thoen@fys.kuleuven.be
2008-06-18
Dielectric spectroscopy has often been used to study confinement effects in alkylcyanobiphenyl liquid crystals. In this paper, we highlight some of the effects that have been discovered previously and add new data and interpretation. Aerosil nanoparticles form a hydrogen bonded random porous network. In dispersions of alkylcyanobiphenyls with aerosils, an additional slow process arises, that we ascribe to the relaxation of liquid crystal molecules in close interaction with these nanoparticles. Their relaxation is retarded by a hydrogen bond interaction between the cyano group of the liquid crystals and an aerosil surface hydroxyl group. A similar surface process is also observed in Vycor porous glass, a random rigid structure with small pores. A comparison of the temperature dependence of the relaxation times of the surface processes in decylcyanobiphenyl and isopentylcyanobiphenyl is made, both for Vycor and aerosil confinement. In decylcyanobiphenyl, the temperature dependence for the bulk and surface processes is Arrhenius (in a limited temperature range above the melting point), except in Vycor, where it is a Vogel-Fulcher-Tamman dependence (over a much broader temperature range). In bulk and confined isopentylcyanobiphenyl, the molecular processes have a Vogel-Fulcher-Tamman dependence, whereas the surface processes have an Arrhenius one. Another effect is the acceleration of the rotation around the short molecular axis in confinement, and particularly in aerosil dispersions. This is a consequence of the disorder introduced in the liquid crystalline phase. The disorder drives the relaxation time towards a more isotropic value, resulting in an acceleration for the short axis rotation.
Zan, Hsiao-Wen; Yeh, Chun-Cheng; Meng, Hsin-Fei; Tsai, Chuang-Chuang; Chen, Liang-Hao
2012-07-10
An effective approach to reduce defects and increase electron mobility in a-IGZO thin-film transistors (a-IGZO TFTs) is introduced. A strong reduction layer, calcium, is capped onto the back interface of a-IGZO TFT. After calcium capping, the effective electron mobility of a-IGZO TFT increases from 12 cm(2) V(-1) s(-1) to 160 cm(2) V(-1) s(-1). This high mobility is a new record, which implies that the proposed defect reduction effect is key to improve electron transport in oxide semiconductor materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Novelli, Anna; Belzig, Wolfgang; Nitzan, Abraham
2015-01-01
The time evolution and the asymptotic outcome of a Landau-Zener-Stueckelberg-Majorana (LZ) process under continuous weak non-selective measurement is analyzed. We compare two measurement protocols in which the populations of either the adiabatic or the non-adiabatic levels are (continuously and weakly) monitored. The weak measurement formalism, described using a Gaussian Kraus operator, leads to a time evolution characterized by a Markovian dephasing process, which, in the non-adiabatic measurement protocol is similar to earlier studies of LZ dynamics in a dephasing environment. Casting the problem in the language of measurement theory makes it possible for us to compare diabatic and adiabatic measurement scenarios, to consider engineered dephasing as a control device and to examine the manifestation of the Zeno effect under the different measurement protocols. In particular, under measurement of the non-adiabatic populations, the Zeno effect is manifested not as a freezing of the measured system in its initial state, but rather as an approach to equal asymptotic populations of the two diabatic states. This behavior can be traced to the way by which the weak measurement formalism behaves in the strong measurement limit, with a built-in relationship between measurement time and strength.
International Nuclear Information System (INIS)
Novelli, Anna; Belzig, Wolfgang; Nitzan, Abraham
2015-01-01
The time evolution and the asymptotic outcome of a Landau–Zener–Stueckelberg–Majorana (LZ) process under continuous weak non-selective measurement is analyzed. We compare two measurement protocols in which the populations of either the adiabatic or the non-adiabatic levels are (continuously and weakly) monitored. The weak measurement formalism, described using a Gaussian Kraus operator, leads to a time evolution characterized by a Markovian dephasing process, which, in the non-adiabatic measurement protocol is similar to earlier studies of LZ dynamics in a dephasing environment. Casting the problem in the language of measurement theory makes it possible for us to compare diabatic and adiabatic measurement scenarios, to consider engineered dephasing as a control device and to examine the manifestation of the Zeno effect under the different measurement protocols. In particular, under measurement of the non-adiabatic populations, the Zeno effect is manifested not as a freezing of the measured system in its initial state, but rather as an approach to equal asymptotic populations of the two diabatic states. This behavior can be traced to the way by which the weak measurement formalism behaves in the strong measurement limit, with a built-in relationship between measurement time and strength. (paper)
Biological Maturity Status Strongly Intensifies the Relative Age Effect in Alpine Ski Racing.
Directory of Open Access Journals (Sweden)
Lisa Müller
Full Text Available The relative age effect (RAE is a well-documented phenomenon in youth sports. This effect exists when the relative age quarter distribution of selected athletes shows a biased distribution with an over-representation of relatively older athletes. In alpine ski racing, it exists in all age categories (national youth levels up to World Cup. Studies so far could demonstrate that selected ski racers are relatively older, taller and heavier. It could be hypothesized that relatively younger athletes nearly only have a chance for selection if they are early maturing. However, surprisingly this influence of the biological maturity status on the RAE could not be proven, yet. Therefore, the aim of the present study was to investigate the influence of the biological maturity status on the RAE in dependence of the level of competition. The study investigated 372 elite youth ski racers: 234 provincial ski racers (P-SR; high level of competition and 137 national ski racers (N-SR; very high level of competition. Anthropometric characteristics were measured to calculate the age at peak height velocity (APHV as an indicator of the biological maturity status. A significant RAE was present among both P-SR and N-SR, with a larger effect size among the latter group. The N-SR significantly differed in APHV from the P-SR. The distribution of normal, early and late maturing athletes significantly differed from the expected normal distribution among the N-SR, not among the P-SR. Hardly any late maturing N-SR were present; 41.7% of the male and 34% of the female N-SR of the last relative age quarter were early maturing. These findings clearly demonstrate the significant influence of the biological maturity status on the selection process of youth alpine ski racing in dependence of the level of competition. Relatively younger athletes seem to have a chance of selection only if they are early maturing.
Functional integral and effective Hamiltonian t-J-V model of strongly correlated electron system
International Nuclear Information System (INIS)
Belinicher, V.I.; Chertkov, M.V.
1990-09-01
The functional integral representation for the generating functional of t-J-V model is obtained. In the case close to half filling this functional integral representation reduces the conventional Hamiltonian of t-J-V model to the Hamiltonian of the system containing holes and spins 1/2 at each lattice size. This effective Hamiltonian coincides with that one obtained one of the authors by different method. This Hamiltonian and its dynamical variables can be used for description of different magnetic phases of t-J-V model. (author). 16 refs
The odd Voigt effect under a strong electric field in semiconductors
International Nuclear Information System (INIS)
Nguyen Hong Shon.
1991-08-01
The high frequency conductivity tensor σ ik (ω) in the linear approximation of magnetic field H and in the quadratic approximation of external dc electric field is derived by solving Boltzmann equation. The magneto-optical phenomena in the Voigt configuration (when a probe electro-magnetic wave propagates across a magnetic field) are investigated. It is shown that the birefringence and dichroism have a component that is odd (linear) in the magnetic fields and predominate over the even effect in the weak magnetic field. (author). 8 refs
Strong temperature effect on the sizes of the Cooper pairs in a two-band superconductor
Örd, Teet; Rägo, Küllike; Vargunin, Artjom; Litak, Grzegorz
2018-01-01
We study the temperature dependencies of the mean sizes of the Cooper pairs in a two-band BCS-type s-wave superconductivity model with coupling cut-off in the momentum space. It is found that, in contrast to single-band systems, the size of Cooper pairs in the weaker superconductivity band can significantly decrease with a temperature increase due to an interband proximity effect. The relevant spatial behaviour of the wave functions of the Cooper pairs is analyzed. The results also indicate a possibility that the size of Cooper pairs in two-band systems may increase with an increase in temperature.
International Nuclear Information System (INIS)
Lin, L.; Sperber, D.
1976-01-01
In two recent papers the instability of the quasi-particle vacuum was related to the high-spin anomaly in rotational nuclear states. The direct consequence of this fact is that the system will make a ''phase transition'' under that situation. Studying the induced rotational asymmetry effect, in the present paper another theoretical fact is discussed, which support this ''phase transition''. Furthermore, it is shown that when this ''phase transition'' occurs, in order to have a proper description of the system, a modification of the physical ground state is necessary which suggests a microscopic theory of band mixing for high spin anomaly in rotational nuclear states
Effective temporal resolution in pump-probe spectroscopy with strongly chirped pulses
International Nuclear Information System (INIS)
Polli, D.; Lanzani, G.; Brida, D.; Cerullo, G.; Mukamel, S.
2010-01-01
This paper introduces a general theoretical description of femtosecond pump-probe spectroscopy with chirped pulses whose joint spectral and temporal profile is expressed by Wigner spectrograms. We demonstrate that the actual experimental time resolution intimately depends on the pulse-sample interaction and that the commonly used instrumental response function needs to be replaced by a sample-dependent effective response function. We also show that, using the proper configurations in excitation and/or detection, it is possible to overcome the temporal smearing of the measured dynamics due to chirp-induced pulse broadening and recover the temporal resolution that would be afforded by the transform-limited pulses. We verify these predictions with experiments using broadband chirped pump and probe pulses. Our results allow optimization of the temporal resolution in the common case when the chirp of the pump and/or probe pulse is not corrected and may be extended to a broad range of time-resolved experiments.
Absence of strong strain effects in behavioral analyses of Shank3-deficient mice
Directory of Open Access Journals (Sweden)
Elodie Drapeau
2014-06-01
Full Text Available Haploinsufficiency of SHANK3, caused by chromosomal abnormalities or mutations that disrupt one copy of the gene, leads to a neurodevelopmental syndrome called Phelan-McDermid syndrome, symptoms of which can include absent or delayed speech, intellectual disability, neurological changes and autism spectrum disorders. The SHANK3 protein forms a key structural part of the post-synaptic density. We previously generated and characterized mice with a targeted disruption of Shank3 in which exons coding for the ankyrin-repeat domain were deleted and expression of full-length Shank3 was disrupted. We documented specific deficits in synaptic function and plasticity, along with reduced reciprocal social interactions, in Shank3 heterozygous mice. Changes in phenotype owing to a mutation at a single locus are quite frequently modulated by other loci, most dramatically when the entire genetic background is changed. In mice, each strain of laboratory mouse represents a distinct genetic background and alterations in phenotype owing to gene knockout or transgenesis are frequently different across strains, which can lead to the identification of important modifier loci. We have investigated the effect of genetic background on phenotypes of Shank3 heterozygous, knockout and wild-type mice, using C57BL/6, 129SVE and FVB/Ntac strain backgrounds. We focused on observable behaviors with the goal of carrying out subsequent analyses to identify modifier loci. Surprisingly, there were very modest strain effects over a large battery of analyses. These results indicate that behavioral phenotypes associated with Shank3 haploinsufficiency are largely strain-independent.
Energy Technology Data Exchange (ETDEWEB)
Aguirre, R.M.; Paoli, A.L. de [Universidad Nacional de La Plata, and IFLP, Departamento de Fisica, Facultad de Ciencias Exactas, La Plata (Argentina)
2016-11-15
We obtain the covariant propagator at finite temperature for interacting baryons immersed in a strong magnetic field. The effect of the intrinsic magnetic moments on the Green function are fully taken into account. We make an expansion in terms of eigenfunctions of a Dirac field, which leads us to a compact form of its propagator. We present some simple applications of these propagators, where the statistical averages of nuclear currents and energy density are evaluated. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Benabbas, Abdelkrim; Salna, Bridget; Sage, J. Timothy; Champion, Paul M., E-mail: champ@neu.edu [Department of Physics and Center for Interdisciplinary Research on Complex Systems,Northeastern University, Boston, Massachusetts 02115 (United States)
2015-03-21
Analytical models describing the temperature dependence of the deep tunneling rate, useful for proton, hydrogen, or hydride transfer in proteins, are developed and compared. Electronically adiabatic and non-adiabatic expressions are presented where the donor-acceptor (D-A) motion is treated either as a quantized vibration or as a classical “gating” distribution. We stress the importance of fitting experimental data on an absolute scale in the electronically adiabatic limit, which normally applies to these reactions, and find that vibrationally enhanced deep tunneling takes place on sub-ns timescales at room temperature for typical H-bonding distances. As noted previously, a small room temperature kinetic isotope effect (KIE) does not eliminate deep tunneling as a major transport channel. The quantum approach focuses on the vibrational sub-space composed of the D-A and hydrogen atom motions, where hydrogen bonding and protein restoring forces quantize the D-A vibration. A Duschinsky rotation is mandated between the normal modes of the reactant and product states and the rotation angle depends on the tunneling particle mass. This tunnel-mass dependent rotation contributes substantially to the KIE and its temperature dependence. The effect of the Duschinsky rotation is solved exactly to find the rate in the electronically non-adiabatic limit and compared to the Born-Oppenheimer (B-O) approximation approach. The B-O approximation is employed to find the rate in the electronically adiabatic limit, where we explore both harmonic and quartic double-well potentials for the hydrogen atom bound states. Both the electronically adiabatic and non-adiabatic rates are found to diverge at high temperature unless the proton coupling includes the often neglected quadratic term in the D-A displacement from equilibrium. A new expression is presented for the electronically adiabatic tunnel rate in the classical limit for D-A motion that should be useful to experimentalists working
Aghighi, Alireza; Comtois, Philippe
2017-09-01
Self-organization of spontaneous activity of a network of active elements is important to the general theory of reaction-diffusion systems as well as for pacemaking activity to initiate beating of the heart. Monolayer cultures of neonatal rat ventricular myocytes, consisting of resting and pacemaker cells, exhibit spontaneous activation of their electrical activity. Similarly, one proposed approach to the development of biopacemakers as an alternative to electronic pacemakers for cardiac therapy is based on heterogeneous cardiac cells with resting and spontaneously beating phenotypes. However, the combined effect of pacemaker characteristics, density, and spatial distribution of the pacemaker cells on spontaneous activity is unknown. Using a simple stochastic pattern formation algorithm, we previously showed a clear nonlinear dependency of spontaneous activity (occurrence and amplitude of spontaneous period) on the spatial patterns of pacemaker cells. In this study, we show that this behavior is dependent on the pacemaker cell characteristics, with weaker pacemaker cells requiring higher density and larger clusters to sustain multicellular activity. These multicellular structures also demonstrated an increased sensitivity to voltage noise that favored spontaneous activity at lower density while increasing temporal variation in the period of activity. This information will help researchers overcome the current limitations of biopacemakers.
The strong thermoelectric effect in nanocarbon generated by the ballistic phonon drag of electrons
International Nuclear Information System (INIS)
Eidelman, E D; Vul', A Ya
2007-01-01
The thermoelectric power and thermoelectric figure of merit for carbon nanostructure consisting of graphite-like (sp 2 ) and diamond-like (sp 3 ) regions have been investigated. The probability of electron collisions with quasi-ballistic phonons in sp 2 regions has been analysed for the first time. We have shown that the probability is not small. We have analysed the influence of various factors on the process of the electron-ballistic phonon drag (the phonon drag effect). The thermoelectric power and thermoelectric figure of merit under conditions of ballistic transport were found to be substantially higher than those in the cases of drag by thermalized phonons and of electron diffusion. The thermoelectric figure of merit (ZT) in the case of a ballistic phonon contribution to the phonon drag of electrons should be 50 times that for chaotic phonons and 500 times that in the case of the diffusion process. In that case ZT should be a record (ZT≥2-3)
Effect of strong acids on red mud structural and fluoride adsorption properties.
Liang, Wentao; Couperthwaite, Sara J; Kaur, Gurkiran; Yan, Cheng; Johnstone, Dean W; Millar, Graeme J
2014-06-01
The removal of fluoride using red mud has been improved by acidifying red mud with hydrochloric, nitric and sulphuric acid. The acidification of red mud causes sodalite and cancrinite phases to dissociate, confirmed by the release of sodium and aluminium into solution as well as the disappearance of sodalite bands and peaks in infrared and X-ray diffraction data. The dissolution of these mineral phases increases the amount of available iron and aluminium oxide/hydroxide sites that are accessible for the adsorption of fluoride. However, concentrated acids have a negative effect on adsorption due to the dissolution of these iron and aluminium oxide/hydroxide sites. The removal of fluoride is dependent on the charge of iron and aluminium oxide/hydroxides on the surface of red mud. Acidifying red mud with hydrochloric, nitric and sulphuric acid resulted in surface sites of the form ≡SOH2(+) and ≡SOH. Optimum removal is obtained when the majority of surface sites are in the form ≡SOH2(+) as the substitution of a fluoride ion does not cause a significant increase in pH. This investigation shows the importance of having a low and consistent pH for the removal of fluoride from aqueous solutions using red mud. Copyright © 2014 Elsevier Inc. All rights reserved.
Effects of strong electron correlations in Ti8C12 Met-Car
International Nuclear Information System (INIS)
Varganov, Sergey A.; Gordon, Mark S.
2006-01-01
The results of multireference configuration interaction (MRCI) with single and double excitations and single reference coupled cluster (CCSD(T)) calculations on Ti 8 C 12 metallocarbohedryne (Met-Car) are reported. The distortions of the T d structure to D 2d and C 3v structures due to the Jahn-Teller effect are studied. It is shown that the Ti 8 C 12 wave function has significant multireference character. The choice of the active space for multireference self-consistent field (MCSCF) calculations is discussed. The failure of multireference perturbation theory with a small active space is attributed to multiple intruder states. A new, novel type of MCSCF calculation, ORMAS (occupation restricted multiple active spaces) with a large active space are carried out for several electronic states of Ti 8 C 12 . The Jahn-Teller distorted D 2d 1 A 1 (nearly T d ) structure is predicted to be the Ti 8 C 12 ground state. Predictions of the Ti 8 C 12 ionization potential with different ab initio methods are presented
Drastic effect of the Mn-substitution in the strongly correlated semiconductor FeSb2.
Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki
2017-06-01
We report the effects of Mn substitution, corresponding to hole doping, on the electronic properties of the narrow gap semiconductor, FeSb2, using single crystals of Fe1- x Mn x Sb2 grown by the Sb flux method. The orthorhombic Pnnm structure was confirmed by powder X-ray diffraction (XRD) for the pure and Mn-substituted samples. Their crystal structure parameters were refined using the Rietveld method. The chemical composition was investigated by wavelength-dispersive X-ray spectroscopy (WDX). The solubility limit of Mn in FeSb2 is x max ˜ 0.05 and the lattice constants change monotonically with increasing the actual Mn concentration. A drastic change from semiconducting to metallic electronic transports was found at very low Mn concentration at x ˜ 0.01. Our experimental results and analysis indicate that the substitution of a small amount of Mn changes drastically the electronic state in FeSb2 as well as the Co-substitution does: closing of the narrow gap and emergence of the density of states (DOS) at the Fermi level.
Adiabatic temperature change from non-adiabatic measurements
Czech Academy of Sciences Publication Activity Database
Carvalho, A.M.G.; Mejía, C.S.; Ponte, C.A.; Silva, L.E.L.; Kaštil, Jiří; Kamarád, Jiří; Gomes, A.M.
2016-01-01
Roč. 122, č. 3 (2016), s. 1-5, č. článku 246. ISSN 0947-8396 Institutional support: RVO:68378271 Keywords : magnetocaloric effect * adiabatic temperature change * calorimetric device * gadolinium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.455, year: 2016
Maturity Status Strongly Influences the Relative Age Effect in International Elite Under-9 Soccer
Directory of Open Access Journals (Sweden)
Lisa Müller, Josef Gehmaier, Christoph Gonaus, Christian Raschner, Erich Müller
2018-06-01
Full Text Available The aim of the study was to assess the role of the relative age effect (RAE and to investigate the influence of the biological maturity status on the RAE in international under-9 soccer. The birth dates of 222 male participants of the U9 Eurochampionship Soccer Tournament in Vienna in 2016 were analyzed and divided into four relative age quarters (Q1-Q4 and the biological maturity status was assessed with the age at peak height velocity (APHV method. Based on the mean±standard deviation of the APHV, the athletes were divided into three groups of maturity: early, normal and late maturing. Chi-Square-tests were used to assess the difference between the observed and the expected even relative age quarter distribution and to evaluate the difference between the observed distribution of early, normal and late maturing athletes and the expected normal distribution. A univariate analysis of variance was performed to assess differences in the APHV between the relative age quarters. A RAE was present (χ2 = 23.87; p < 0.001; ω = 0.33. A significant difference was found in APHV between the four relative age quarters (F = 9.906; p < 0.001; relatively older athletes were significantly less mature. A significant difference was found between the distribution of early, normal and late maturing athletes and the expected normal distribution for athletes of Q1 (high percentage of late maturing athletes: 27%; χ2 = 17.69; p < 0.001; ω = 0.46 and of Q4 (high percentage of early maturing soccer players: 31%; χ2 = 12.08; p = 0.002; ω = 0.58. These findings demonstrated that the selection process in international soccer, with athletes younger than 9 years, seems to be associated with the biological maturity status and the relative age. Relatively younger soccer players seem to have a better chance for selection for international tournaments, if they enter puberty at an earlier age, whereas relatively older athletes seem to have an increased likelihood for
Approximations to the non-adiabatic particle response in toroidal geometry
International Nuclear Information System (INIS)
Schep, T.J.; Braams, B.J.
1981-08-01
The non-adiabatic part of the particle response to low-frequency electromagnetic modes with long parallel wavelengths is discussed. Analytic approximations to the kernels of the integrals that relate the amplitudes of the perturbed potentials to the non-adiabatic part of the perturbed density in an axisymmetric toroidal configuration are presented and the results are compared with numerical calculations. It is shown that both in the plane slab and in toroidal geometry the kernel contains a logarithmic singularity. This singularity is associated with particles with vanishing parallel velocity so that, in toroidal geometry, it is related with the behaviour of trapped particles near their turning points. In contrast to the plane slab, in toroidal geometry this logarithmic singularity is mainly real and associated with non-resonant particles. Apart from this logarithmic term, the kernel contains a complex regular part arising from resonant as well as from non-resonant particles. The analytic approximations that will be presented make the dispersion relation of drift-type modes in toroidal geometry amenable to analytic as well as to simpler numerical calculation of the growth rate and of the spatial mode structure
Non-adiabatic pressure loss boundary condition for modelling turbocharger turbine pulsating flow
International Nuclear Information System (INIS)
Chiong, M.S.; Rajoo, S.; Romagnoli, A.; Costall, A.W.; Martinez-Botas, R.F.
2015-01-01
Highlights: • Bespoke non-adiabatic pressure loss boundary for pulse flow turbine modelling. • Predictions show convincing results against experimental and literature data. • Predicted pulse pressure propagation is in good agreement with literature data. • New methodology is time efficient and requires minimal geometrical inputs. - Abstract: This paper presents a simplified methodology of pulse flow turbine modelling, as an alternative over the meanline integrated methodology outlined in previous work, in order to make its application to engine cycle simulation codes much more straight forward. This is enabled through the development of a bespoke non-adiabatic pressure loss boundary to represent the turbine rotor. In this paper, turbocharger turbine pulse flow performance predictions are presented along with a comparison of computation duration against the previously established integrated meanline method. Plots of prediction deviation indicate that the mass flow rate and actual power predictions from both methods are highly comparable and are reasonably close to experimental data. However, the new boundary condition required significantly lower computational time and rotor geometrical inputs. In addition, the pressure wave propagation in this simplified unsteady turbine model at different pulse frequencies has also been found to be in agreement with data from the literature, thereby supporting the confidence in its ability to simulate the wave action encountered in turbine pulse flow operation
Franck--Condon factors in studies of dynamics of chemical reactions. IV. Nonadiabatic collisions
International Nuclear Information System (INIS)
Zvijac, D.J.; Ross, J.
1978-01-01
We investigate the application of the Franck--Condon approach to nonadiabatic molecular scattering processes. Computationally simple, analytic formulas are developed to describe the energy dependence of quenching of electronically excited atoms by atoms and molecules. These formulas include the dependence of the Franck--Condon factors on the translational wavefunctions as well as the wavefunctions for the internal degrees of freedom. We use these formulas to evaluate the translational energy dependence of the fine structure transition cross sections for F( 2 P/sub 3/2/)+X→F( 2 P/sub 1/2/)+X, where X= Xe, H + , and H 2 . The cross sections generally increase as the initial translational energy increases. Our results agree semiquantiatively (or better) with those obtained from other theoretical techniques. In the case of F+H + we find that the absolute cross section is sensitive to the analytic form used for the nonadiabatic coupling but our model gives the correct energy dependence. At the energies of our calculations we find only a small amount of vibrational excitation of H 2 . Finally, we use our expressions to interpret some trends of available experimental results on the quenching of Hg ( 3 P 2 → 3 P 1 ) by several molecules. We find that collisional excitation of the internal modes of the molecule becomes more important as the initial translational energy increases. However, these modes do not contribute to the quenching cross section in a statistical fashion
International Nuclear Information System (INIS)
Martin, L. N.; Dmitruk, P.; Gomez, D. O.
2010-01-01
In this work we numerically test a model of Hall magnetohydrodynamics in the presence of a strong mean magnetic field: the reduced Hall magnetohydrodynamic model (RHMHD) derived by [Gomez et al., Phys. Plasmas 15, 102303 (2008)] with the addition of weak compressible effects. The main advantage of this model lies in the reduction of computational cost. Nevertheless, up until now the degree of agreement with the original Hall MHD system and the range of validity in a regime of turbulence were not established. In this work direct numerical simulations of three-dimensional Hall MHD turbulence in the presence of a strong mean magnetic field are compared with simulations of the weak compressible RHMHD model. The results show that the degree of agreement is very high (when the different assumptions of RHMHD, such as spectral anisotropy, are satisfied). Nevertheless, when the initial conditions are isotropic but the mean magnetic field is maintained strong, the results differ at the beginning but asymptotically reach a good agreement at relatively short times. We also found evidence that the compressibility still plays a role in the dynamics of these systems, and the weak compressible RHMHD model is able to capture these effects. In conclusion the weak compressible RHMHD model is a valid approximation of the Hall MHD turbulence in the relevant physical context.
Non-adiabatic pumping in an oscillating-piston model
Chuchem, Maya; Dittrich, Thomas; Cohen, Doron
2012-05-01
We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non-trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.
Kittell, Aaron W.; Hyde, James S.
2015-01-01
Non-adiabatic rapid passage (NARS) electron paramagnetic resonance (EPR) spectroscopy was introduced by Kittell, A.W., Camenisch, T.G., Ratke, J.J. Sidabras, J.W., Hyde, J.S., 2011 as a general purpose technique to collect the pure absorption response. The technique has been used to improve sensitivity relative to sinusoidal magnetic field modulation, increase the range of inter-spin distances that can be measured under near physiological conditions, and enhance spectral resolution in copper (II) spectra. In the present work, the method is extended to CW microwave power saturation of spin-labeled T4 Lysozyme (T4L). As in the cited papers, rapid triangular sweep of the polarizing magnetic field was superimposed on slow sweep across the spectrum. Adiabatic rapid passage (ARP) effects were encountered in samples undergoing very slow rotational diffusion as the triangular magnetic field sweep rate was increased. The paper reports results of variation of experimental parameters at the interface of adiabatic and non-adiabatic rapid sweep conditions. Comparison of the forward (up) and reverse (down) triangular sweeps is shown to be a good indicator of the presence of rapid passage effects. Spectral turning points can be distinguished from spectral regions between turning points in two ways: differential microwave power saturation and differential passage effects. Oxygen accessibility data are shown under NARS conditions that appear similar to conventional field modulation data. However, the sensitivity is much higher, permitting, in principle, experiments at substantially lower protein concentrations. Spectral displays were obtained that appear sensitive to rotational diffusion in the range of rotational correlation times of 10−3 to 10−7 s in a manner that is analogous to saturation transfer spectroscopy. PMID:25917132
Nonadiabatic population transfer in a driven four-level system
International Nuclear Information System (INIS)
Prants, S.V.
1994-01-01
The coherent dynamics of a four-level quantum system with an arbitrary level configuration is described analytically in the modulated polychromatic laser field. The method of dynamical symmetries is invoked to develop the formalism for explicit calculation of the evolution matrix of the system in the resonance fields. The method is free of the usual adiabatic-passage, weak-field approximations, and approximation of the slowly varying amplitudes. The conditions for occurrence of the coherent effects of the total inversion and the total depletion of the initial level of a system driven simultaneously driven simultaneously at several transitions by the laser pulses of arbitrary shape are derived analytically. The obtained results can be applied to problems of the control of quantum processes in multilevel atoms and molecules. 14 refs
Directory of Open Access Journals (Sweden)
Ali Akbar Akhtari
2010-03-01
Full Text Available Bends along open channels always pose difficulties for water transfer systems. One undesirable effect of bends in such channels, i.e. separation of water from inner banks, was studied. For the purposes of this study, the literature on the subject was first reviewed, and a strongly-curved open channel was designed and constructed on the laboratory scale. Several tests were performed to evaluate the accuracy of the lab model, data homogeneity, and systematic errors. The model was then calibrated and the influence of curvature on flow pattern past the curve was investigated. Also, for the first time, the influence of separation walls on flow pattern was investigated. Experimental results on three strongly-curved open channels with a curvature radius to channel width ratio of 1.5 and curvature angles of 30°, 60°, and 90° showed that, in all the cases studied, the effect of flow separation could be observed immediately after the curve. In addition, the greatest effect of flow separation was seen at a distance equal to channel width from the bend end. In the presence of middle walls and flow separation, the effect of water separation reduced at the bend, especially for a curvature of 90°.
Lagrangian Description of Nonadiabatic Particle Motion in Spherical Tori
Energy Technology Data Exchange (ETDEWEB)
R.B. White; Yu.V. Yakovenko; Ya.I. Kolesnichenko
2002-06-21
The ability of a device to provide adiabatic motion of charged particles is crucial for magnetic confinement. As the magnetic field in the present-day spherical tori, e.g., MAST and NSTX, is much lower than in the conventional tokamaks, effects of the finite Larmor radius (FLR) on the motion of fast ions are of importance in these devices, affecting the stochasticity threshold for the interaction of the ions with electromagnetic perturbations. In addition, FLR by itself may result in non-conservation (jumps) of the magnetic moment of particles [4]. In this work we propose a Lagrangian approach to description of the resonant collisionless motion of charged particles under a perturbation, allowing for FLR. The work generalizes results of Ref. [1], where only time-independent perturbations were considered. The approach is used to find the stochasticity thresholds for the Goldston-White-Boozer (GWB) diffusion [2] and the cyclotron-resonance-induced (CRI) diffusion (for the case of the firs t cyclotron resonance, the latter was discovered in Ref. [3]). In addition, a new expression for the magnetic moment variation caused by FLR is found.
Lagrangian Description of Nonadiabatic Particle Motion in Spherical Tori
International Nuclear Information System (INIS)
White, R.B.; Yakovenko, Yu.V.; Kolesnichenko, Ya.I.
2002-01-01
The ability of a device to provide adiabatic motion of charged particles is crucial for magnetic confinement. As the magnetic field in the present-day spherical tori, e.g., MAST and NSTX, is much lower than in the conventional tokamaks, effects of the finite Larmor radius (FLR) on the motion of fast ions are of importance in these devices, affecting the stochasticity threshold for the interaction of the ions with electromagnetic perturbations. In addition, FLR by itself may result in non-conservation (jumps) of the magnetic moment of particles [4]. In this work we propose a Lagrangian approach to description of the resonant collisionless motion of charged particles under a perturbation, allowing for FLR. The work generalizes results of Ref. [1], where only time-independent perturbations were considered. The approach is used to find the stochasticity thresholds for the Goldston-White-Boozer (GWB) diffusion [2] and the cyclotron-resonance-induced (CRI) diffusion (for the case of the first cyclotron resonance, the latter was discovered in Ref. [3]). In addition, a new expression for the magnetic moment variation caused by FLR is found
Janke, Svenja M; Auerbach, Daniel J; Wodtke, Alec M; Kandratsenka, Alexander
2015-09-28
We have constructed a potential energy surface (PES) for H-atoms interacting with fcc Au(111) based on fitting the analytic form of the energy from Effective Medium Theory (EMT) to ab initio energy values calculated with density functional theory. The fit used input from configurations of the H-Au system with Au atoms at their lattice positions as well as configurations with the Au atoms displaced from their lattice positions. It reproduces the energy, in full dimension, not only for the configurations used as input but also for a large number of additional configurations derived from ab initio molecular dynamics (AIMD) trajectories at finite temperature. Adiabatic molecular dynamics simulations on this PES reproduce the energy loss behavior of AIMD. EMT also provides expressions for the embedding electron density, which enabled us to develop a self-consistent approach to simulate nonadiabatic electron-hole pair excitation and their effect on the motion of the incident H-atoms. For H atoms with an energy of 2.7 eV colliding with Au, electron-hole pair excitation is by far the most important energy loss pathway, giving an average energy loss ≈3 times that of the adiabatic case. This increased energy loss enhances the probability of the H-atom remaining on or in the Au slab by a factor of 2. The most likely outcome for H-atoms that are not scattered also depends prodigiously on the energy transfer mechanism; for the nonadiabatic case, more than 50% of the H-atoms which do not scatter are adsorbed on the surface, while for the adiabatic case more than 50% pass entirely through the 4 layer simulation slab.
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Jayanta; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in
2016-01-13
Highlights: • Decomposition mechanisms of model energetic salt, guanidium triazolate, are explored. • Decomposition pathways are electronically nonadiabatic. • CASPT2, CASMP2 and CASSCF methodologies are employed. • N{sub 2} and NH{sub 3} are predicted to be the most possible initial decomposition products. - Abstract: Electronically nonadiabatic decomposition pathways of guanidium triazolate are explored theoretically. Nonadiabatically coupled potential energy surfaces are explored at the complete active space self-consistent field (CASSCF) level of theory. For better estimation of energies complete active space second order perturbation theories (CASPT2 and CASMP2) are also employed. Density functional theory (DFT) with B3LYP functional and MP2 level of theory are used to explore subsequent ground state decomposition pathways. In comparison with all possible stable decomposition products (such as, N{sub 2}, NH{sub 3}, HNC, HCN, NH{sub 2}CN and CH{sub 3}NC), only NH{sub 3} (with NH{sub 2}CN) and N{sub 2} are predicted to be energetically most accessible initial decomposition products. Furthermore, different conical intersections between the S{sub 1} and S{sub 0} surfaces, which are computed at the CASSCF(14,10)/6-31G(d) level of theory, are found to play an essential role in the excited state deactivation process of guanidium triazolate. This is the first report on the electronically nonadiabatic decomposition mechanisms of isolated guanidium triazolate salt.
DEFF Research Database (Denmark)
Bochenkova, Anastasia; Andersen, Lars Henrik
2013-01-01
The anionic wild-type Green Fluorescent Protein (GFP) chromophore defines the entire class of naturally occurring chromophores, which are based on the oxydized tyrosine side chain. The GFP chromophore exhibits an enriched photoinduced non-adiabatic dynamics in the multiple excited-state decay cha...
International Nuclear Information System (INIS)
Matora, I.M.; Merkulov, L.A.
1975-01-01
The effect is considered of two kinds of a dependence of the emission density from the electric field voltage on the emitter surface of a strong-current electron gun (the Schottky law and the ''3/2'' law) upon the choice of a form for the meridional cross section of this emitter at the condition of electron flux laminarity. A calculation example is given for electron gun with close to laminar flow assuming the validity of the Schottky law. The results of calculation of varying the laminar flux character are given which appears when varying parameters of the gun at the voltage 500 kV and current 250 A
Finite-size effect of η-deformed AdS5×S5 at strong coupling
Directory of Open Access Journals (Sweden)
Changrim Ahn
2017-04-01
Full Text Available We compute Lüscher corrections for a giant magnon in the η-deformed (AdS5×S5η using the su(2|2q-invariant S-matrix at strong coupling and compare with the finite-size effect of the corresponding string state, derived previously. We find that these two results match and confirm that the su(2|2q-invariant S-matrix is describing world-sheet excitations of the η-deformed background.
Next-to-leading order strong interaction corrections to the ΔF = 2 effective Hamiltonian in the MSSM
International Nuclear Information System (INIS)
Ciuchini, Marco; Franco, E.; Guadagnoli, D.; Lubicz, Vittorio; Porretti, V.; Silvestrini, L.
2006-01-01
We compute the next-to-leading order strong interaction corrections to gluino-mediated ΔF = 2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coefficients of the ΔF = 2 effective Hamiltonian relevant for neutral meson mixings. We find that the matching scale uncertainty is largely reduced at the next-to-leading order, typically from about 10-15% to few percent
Energy Technology Data Exchange (ETDEWEB)
Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2013-12-07
We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.
International Nuclear Information System (INIS)
Mironova, I A; Usoskin, I G
2014-01-01
This letter presents a summary of a phenomenological study of the response of the polar stratosphere to strong solar energetic particle (SEP) events corresponding to ground level enhancements (GLEs) of cosmic rays. This work is focused on evaluation of the possible influence of the atmospheric ionization caused by SEPs upon formation of aerosol particles in the stratosphere over polar regions. Following case studies of two major SEP/GLE events, in January 2005 and September 1989, and their possible effects on polar stratospheric aerosols, we present here the results of an analysis of variations of the daily profiles of the stratospheric aerosol parameters (aerosol extinction for different wavelengths, as well as Ångstrom exponent) for both polar hemispheres during SEP/GLE events of July 2000, April 2001 and October 2003, which form already five clear cases corresponding to extreme and strong SEP/GLE events. The obtained results suggest that an enhancement of ionization rate by a factor of about two in the polar region with night/cold/winter conditions can lead to the formation/growing of aerosol particles in the altitude range of 10–25 km. We also present a summary of the investigated effects based on the phenomenological study of the atmospheric application of extreme SEP events. (paper)
Directory of Open Access Journals (Sweden)
Laura J Falkenberg
Full Text Available Foundation species, such as kelp, exert disproportionately strong community effects and persist, in part, by dominating taxa that inhibit their regeneration. Human activities which benefit their competitors, however, may reduce stability of communities, increasing the probability of phase-shifts. We tested whether a foundation species (kelp would continue to inhibit a key competitor (turf-forming algae under moderately increased local (nutrient and near-future forecasted global pollution (CO(2. Our results reveal that in the absence of kelp, local and global pollutants combined to cause the greatest cover and mass of turfs, a synergistic response whereby turfs increased more than would be predicted by adding the independent effects of treatments (kelp absence, elevated nutrients, forecasted CO(2. The positive effects of nutrient and CO(2 enrichment on turfs were, however, inhibited by the presence of kelp, indicating the competitive effect of kelp was stronger than synergistic effects of moderate enrichment of local and global pollutants. Quantification of physicochemical parameters within experimental mesocosms suggests turf inhibition was likely due to an effect of kelp on physical (i.e. shading rather than chemical conditions. Such results indicate that while forecasted climates may increase the probability of phase-shifts, maintenance of intact populations of foundation species could enable the continued strength of interactions and persistence of communities.
Panáček, Aleš; Smékalová, Monika; Kilianová, Martina; Prucek, Robert; Bogdanová, Kateřina; Večeřová, Renata; Kolář, Milan; Havrdová, Markéta; Płaza, Grażyna Anna; Chojniak, Joanna; Zbořil, Radek; Kvítek, Libor
2015-12-28
The resistance of bacteria towards traditional antibiotics currently constitutes one of the most important health care issues with serious negative impacts in practice. Overcoming this issue can be achieved by using antibacterial agents with multimode antibacterial action. Silver nano-particles (AgNPs) are one of the well-known antibacterial substances showing such multimode antibacterial action. Therefore, AgNPs are suitable candidates for use in combinations with traditional antibiotics in order to improve their antibacterial action. In this work, a systematic study quantifying the synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was performed. Employing the microdilution method as more suitable and reliable than the disc diffusion method, strong synergistic effects were shown for all tested antibiotics combined with AgNPs at very low concentrations of both antibiotics and AgNPs. No trends were observed for synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs, indicating non-specific synergistic effects. Moreover, a very low amount of silver is needed for effective antibacterial action of the antibiotics, which represents an important finding for potential medical applications due to the negligible cytotoxic effect of AgNPs towards human cells at these concentration levels.
Kodama, Yukinobu; Shiokawa, Yumi; Nakamura, Tadahiro; Kurosaki, Tomoaki; Aki, Keisei; Nakagawa, Hiroo; Muro, Takahiro; Kitahara, Takashi; Higuchi, Norihide; Sasaki, Hitoshi
2014-01-01
We developed a novel small interfering RNA (siRNA) delivery system using a ternary complex with polyethyleneimine (PEI) and γ-polyglutamic acid (γ-PGA), which showed silencing effect and no cytotoxicity. The binary complexes of siRNA with PEI were approximately 73-102 nm in particle size and 45-52 mV in ζ-potential. The silencing effect of siRNA/PEI complexes increased with an increase of PEI, and siRNA/PEI complexes with a charge ratio greater than 16 showed significant luciferase knockdown in a mouse colon carcinoma cell line regularly expressing luciferase (Colon26/Luc cells). However, strong cytotoxicity and blood agglutination were observed in the siRNA/Lipofectamine complex and siRNA/PEI16 complex. Recharging cationic complexes with an anionic compound was reported to be a promising method for overcoming these toxicities. We therefore prepared ternary complexes of siRNA with PEI (charge ratio 16) by the addition of γ-PGA to reduce cytotoxicity and deliver siRNA. As expected, the cytotoxicity of the ternary complexes decreased with an increase of γ-PGA content, which decreased the ζ-potential of the complexes. A strong silencing effect comparable to siRNA/Lipofectamine complex was discovered in ternary complexes including γ-PGA with an anionic surface charge. The high incorporation of ternary complexes into Colon26/Luc cells was confirmed with fluorescence microcopy. Having achieved knockdown of an exogenously transfected gene, the ability of the complex to mediate knockdown of an endogenous housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), was assessed in B16-F10 cells. The ternary complex (siRNA/PEI16/γ-PGA12 complex) exhibited a significant GAPDH knockdown effect. Thus, we developed a useful siRNA delivery system.
Energy Technology Data Exchange (ETDEWEB)
Martens, Craig C., E-mail: cmartens@uci.edu
2016-12-20
In this paper, we revisit the semiclassical Liouville approach to describing molecular dynamics with electronic transitions using classical trajectories. Key features of the formalism are highlighted. The locality in phase space and presence of nonclassical terms in the generalized Liouville equations are emphasized and discussed in light of trajectory surface hopping methodology. The representation dependence of the coupled semiclassical Liouville equations in the diabatic and adiabatic bases are discussed and new results for the transformation theory of the Wigner functions representing the corresponding density matrix elements given. We show that the diagonal energies of the state populations are not conserved during electronic transitions, as energy is stored in the electronic coherence. We discuss the implications of this observation for the validity of imposing strict energy conservation in trajectory based methods for simulating nonadiabatic processes.
Generalization of the geometric optical series approach for nonadiabatic scattering problems
International Nuclear Information System (INIS)
Herman, M.F.
1982-01-01
The geometric optical series approach of Bremmer is generalized for multisurface nonadiabatic scattering problems. This method yields the formal solution of the Schroedinger equation as an infinite series of multiple integrals. The zeroth order term corresponds to WKB propagation on a single adiabatic surface, while the general Nth order term involves N reflections and/or transitions between surfaces accompanied by ''free,'' single surface semiclassical propagation between the points of reflection and transition. Each term is integrated over all possible transition and reflection points. The adiabatic and diabatic limits of this expression are discussed. Numerical results, in which all reflections are ignored, are presented for curve crossing and noncrossing problems. These results are compared to exact quantum results and are shown to be highly accurate
Nonadiabatic quantum dynamics and laser control of Br2 in solid argon.
Accardi, A; Borowski, A; Kühn, O
2009-07-02
A five-dimensional reaction surface-vibronic coupling model is introduced to describe the B- to C-state predissociation dynamics of Br(2) occupying a double substitutional lattice site in a face-centered cubic argon crystal at low temperatures. The quantum dynamics driven by a Franck-Condon vertical excitation is investigated, revealing the role of matrix cage compression for efficient nonadiabatic transitions. Vibrational preexcitation of the Br(2) bond in the electronic ground state can be used to access a different regime of predissociation which does not require substantial matrix compression because the Franck-Condon window shifts into the energetic range of the B-C level crossing. Using optimal control theory, it is shown how vibrational preexcitation can be achieved via a pump-dump-type mechanism involving the repulsive C state.
Energy Technology Data Exchange (ETDEWEB)
Nelson, Tammie Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tretiak, Sergei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-01-06
Understanding and controlling excited state dynamics lies at the heart of all our efforts to design photoactive materials with desired functionality. This tailor-design approach has become the standard for many technological applications (e.g., solar energy harvesting) including the design of organic conjugated electronic materials with applications in photovoltaic and light-emitting devices. Over the years, our team has developed efficient LANL-based codes to model the relevant photophysical processes following photoexcitation (spatial energy transfer, excitation localization/delocalization, and/or charge separation). The developed approach allows the non-radiative relaxation to be followed on up to ~10 ps timescales for large realistic molecules (hundreds of atoms in size) in the realistic solvent dielectric environment. The Collective Electronic Oscillator (CEO) code is used to compute electronic excited states, and the Non-adiabatic Excited State Molecular Dynamics (NA-ESMD) code is used to follow the non-adiabatic dynamics on multiple coupled Born-Oppenheimer potential energy surfaces. Our preliminary NA-ESMD simulations have revealed key photoinduced mechanisms controlling competing interactions and relaxation pathways in complex materials, including organic conjugated polymer materials, and have provided a detailed understanding of photochemical products and intermediates and the internal conversion process during the initiation of energetic materials. This project will be using LANL-based CEO and NA-ESMD codes to model nonradiative relaxation in organic and energetic materials. The NA-ESMD and CEO codes belong to a class of electronic structure/quantum chemistry codes that require large memory, “long-queue-few-core” distribution of resources in order to make useful progress. The NA-ESMD simulations are trivially parallelizable requiring ~300 processors for up to one week runtime to reach a meaningful restart point.
International Nuclear Information System (INIS)
Moritz, B; Johnston, S; Greven, M; Shen, Z-X; Devereaux, T P; Schmitt, F; Meevasana, W; Motoyama, E M; Lu, D H; Kim, C; Scalettar, R T
2009-01-01
Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). This paper demonstrates, using a combination of new ARPES measurements and quantum Monte Carlo simulations, that the HEA is not simply the by-product of matrix element effects, but rather represents a cross-over from a quasi-particle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character, in both hole- and electron-doped cuprates. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying both hole and electron doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram.
Directory of Open Access Journals (Sweden)
Leila Karhunen
2012-01-01
Full Text Available This study aimed to investigate factors associated with weight management, especially whether satiety value of food as a part of a weight-maintenance diet would affect self-regulation of food intake and weight management. Altogether 82 obese subjects completed the study consisting of weight-loss and weight-maintenance (WM periods. During the WM, subjects were randomized into higher- and lower-satiety food groups. No differences were observed in the changes in body weight, energy intake, or eating behaviour between the groups, even despite the different macronutrient compositions of the diets. However, when regarding all study subjects, success in WM was most strongly associated with a greater increase in the flexible control of eating and experience of greater easiness of WM and control of food intake and a greater decrease in uncontrollable eating and psychological distress. Psychobehavioural factors seem to be more strongly associated with successful weight management than the predetermined satiety effect or other characteristics of the diet.
Noise-induced extinction for a ratio-dependent predator-prey model with strong Allee effect in prey
Mandal, Partha Sarathi
2018-04-01
In this paper, we study a stochastically forced ratio-dependent predator-prey model with strong Allee effect in prey population. In the deterministic case, we show that the model exhibits the stable interior equilibrium point or limit cycle corresponding to the co-existence of both species. We investigate a probabilistic mechanism of the noise-induced extinction in a zone of stable interior equilibrium point. Computational methods based on the stochastic sensitivity function technique are applied for the analysis of the dispersion of random states near stable interior equilibrium point. This method allows to construct a confidence domain and estimate the threshold value of the noise intensity for a transition from the coexistence to the extinction.
Zhou, Xue; Li, Mingzhu; Wang, Kang; Li, Huizeng; Li, Yanan; Li, Chang; Yan, Yongli; Zhao, Yongsheng; Song, Yanlin
2018-03-25
Stimulated emission in perovskite-embedded polymer opal structures is investigated. A polymer opal structure is filled with a perovskite, and perovskite photonic crystals are prepared. The spontaneous emission of the perovskite embedded in the polymer opal structures exhibits clear signatures of amplified spontaneous emission (ASE) via gain modulation. The difference in refractive-index contrast between the perovskite and the polymer opal is large enough for retaining photonic-crystals properties. The photonic band gap has a strong effect on the fluorescence emission intensity and lifetime. The stimulated emission spectrum exhibits a narrow ASE rather than a wide fluorescence peak in the thin film. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Be'er, Shay; Assaf, Michael; Meerson, Baruch
2015-06-01
We study the dynamics of colonization of a territory by a stochastic population at low immigration pressure. We assume a sufficiently strong Allee effect that introduces, in deterministic theory, a large critical population size for colonization. At low immigration rates, the average precolonization population size is small, thus invalidating the WKB approximation to the master equation. We circumvent this difficulty by deriving an exact zero-flux solution of the master equation and matching it with an approximate nonzero-flux solution of the pertinent Fokker-Planck equation in a small region around the critical population size. This procedure provides an accurate evaluation of the quasistationary probability distribution of population sizes in the precolonization state and of the mean time to colonization, for a wide range of immigration rates. At sufficiently high immigration rates our results agree with WKB results obtained previously. At low immigration rates the results can be very different.
Strong spin-filtering and spin-valve effects in a molecular V–C60–V contact
Directory of Open Access Journals (Sweden)
Mohammad Koleini
2012-08-01
Full Text Available Motivated by the recent achievements in the manipulation of C60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111 surface using first-principles calculations. For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%. Moreover, we find a significant change in the conductance between parallel and anti-parallel spin polarizations in the junction (86% which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems.
Strong spin-filtering and spin-valve effects in a molecular V-C-60-V contact
DEFF Research Database (Denmark)
Koleini, Mohammad; Brandbyge, Mads
2012-01-01
Motivated by the recent achievements in the manipulation of C-60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C-60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111) surface using first-principles calculations....... For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C-60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%). Moreover, we find a significant change...... in the conductance between parallel and anti-parallel spin polarizations in the junction (86%) which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems....
Energy Technology Data Exchange (ETDEWEB)
Kamble, Ramesh B., E-mail: rbk.physics@coep.ac.in [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Department of Physics, College of Engineering, Pune 411005, Maharashtra (India); Tanty, Narendra; Patra, Ananya; Prasad, V. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India)
2016-08-22
We report the potential field emission of highly conducting metallic perovskite lanthanum nickelate (LaNiO{sub 3}) from the nanostructured pyramidal and whisker shaped tips as electron emitters. Nano particles of lanthanum nickelate (LNO) were prepared by sol-gel route. Structural and morphological studies have been carried out. Field emission of LNO exhibited high emission current density, J = 3.37 mA/cm{sup 2} at a low threshold electric field, E{sub th} = 16.91 V/μm, obeying Fowler–Nordheim tunneling. The DC electrical resistivity exhibited upturn at 11.6 K indicating localization of electron at low temperature. Magnetoresistance measurement at different temperatures confirmed strong localization in nanostructured LNO obeying Anderson localization effect at low temperature.
International Nuclear Information System (INIS)
Li, Keqiao; Cai, Dehua; Liu, Yue; Jiang, Jingkai; Sun, Wei; He, Guogeng
2017-01-01
Graphical abstract: A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle using R290/refrigeration oil has been thermodynamically analyzed. Influences of the ejector and the non-adiabatic absorber applications on the system performance and other system operation parameters have been investigated. The simulation results will be of great help to the miniaturization and practical application of the air-cooled absorption refrigeration system. - Highlights: • A novel air-cooled non-adiabatic ejection-absorption refrigeration cycle is proposed. • Influences of the ejector and the air-cooled non-adiabatic absorber applications on the system performance are investigated. • Variations of system performance and other system operation parameters are investigated. • R290/refrigeration oil mixture used as working pairs is analyzed. - Abstract: This paper thermodynamically analyzes a novel air-cooled non-adiabatic ejection-absorption refrigeration cycle with R290/oil mixture driven by exhaust heat. An ejector located at the upstream of the non-adiabatic absorber is employed to improve the cycle performance. Variations of COP, circulation ratio and component heat load of the system as a function of generating temperature, pressure ratio, absorption temperature, condensing temperature and evaporating temperature have been investigated in this work. The simulation results show that, compared with the conventional absorption refrigeration cycle, this non-adiabatic ejection-absorption refrigeration cycle has higher absorption efficiency, better performance, wider working condition range and lower total heat load and its COP can reach as high as 0.5297. The implementation of the ejector and the non-adiabatic absorber helps to realize the miniaturization and wider application of the absorption refrigeration system. In addition, R290/oil mixture is a kind of highly potential working pairs for absorption refrigeration.
Dessi, Roberta; Rustichini, Aldo
2015-01-01
A large literature in psychology, and more recently in economics, has argued that monetary rewards can reduce intrinsic motivation. We investigate whether the negative impact persists when intrinsic motivation is strong, and test this hypothesis experimentally focusing on the motivation to undertake interesting and challenging tasks, informative about individual ability. We find that this type of task can generate strong intrinsic motivation, that is impervious to the effect of monetary incen...
Directory of Open Access Journals (Sweden)
Herranz Raul
2012-02-01
Full Text Available Abstract Background Many biological systems respond to the presence or absence of gravity. Since experiments performed in space are expensive and can only be undertaken infrequently, Earth-based simulation techniques are used to investigate the biological response to weightlessness. A high gradient magnetic field can be used to levitate a biological organism so that its net weight is zero. Results We have used a superconducting magnet to assess the effect of diamagnetic levitation on the fruit fly D. melanogaster in levitation experiments that proceeded for up to 22 consecutive days. We have compared the results with those of similar experiments performed in another paradigm for microgravity simulation, the Random Positioning Machine (RPM. We observed a delay in the development of the fruit flies from embryo to adult. Microarray analysis indicated changes in overall gene expression of imagoes that developed from larvae under diamagnetic levitation, and also under simulated hypergravity conditions. Significant changes were observed in the expression of immune-, stress-, and temperature-response genes. For example, several heat shock proteins were affected. We also found that a strong magnetic field, of 16.5 Tesla, had a significant effect on the expression of these genes, independent of the effects associated with magnetically-induced levitation and hypergravity. Conclusions Diamagnetic levitation can be used to simulate an altered effective gravity environment in which gene expression is tuned differentially in diverse Drosophila melanogaster populations including those of different age and gender. Exposure to the magnetic field per se induced similar, but weaker, changes in gene expression.
Directory of Open Access Journals (Sweden)
David Leitsch
2017-12-01
Full Text Available The microaerophilic parasites Entamoeba histolytica, Trichomonas vaginalis, and Giardia lamblia annually cause hundreds of millions of human infections which are treated with antiparasitic drugs. Metronidazole is the most often prescribed drug but also other drugs are in use, and novel drugs with improved characteristics are constantly being developed. One of these novel drugs is auranofin, originally an antirheumatic which has been relabelled for the treatment of parasitic infections. Drug effectivity is arguably the most important criterion for its applicability and is commonly assessed in susceptibility assays using in vitro cultures of a given pathogen. However, drug susceptibility assays can be strongly affected by certain compounds in the growth media. In the case of microaerophilic parasites, cysteine which is added in large amounts as an antioxidant is an obvious candidate because it is highly reactive and known to modulate the toxicity of metronidazole in several microaerophilic parasites.In this study, it was attempted to reduce cysteine concentrations as far as possible without affecting parasite viability by performing drug susceptibility assays under strictly anaerobic conditions in an anaerobic cabinet. Indeed, T. vaginalis and E. histolytica could be grown without any cysteine added and the cysteine concentration necessary to maintain G. lamblia could be reduced to 20%. Susceptibilities to metronidazole were found to be clearly reduced in the presence of cysteine. With auranofin the protective effect of cysteine was extreme, providing protection to concentrations up to 100-fold higher as observed in the absence of cysteine. With three other drugs tested, albendazole, furazolidone and nitazoxanide, all in use against G. lamblia, the effect of cysteine was less pronounced. Oxygen was found to have a less marked impact on metronidazole and auranofin than cysteine but bovine bile which is standardly used in growth media for G
Self-shielding and burn-out effects in the irradiation of strongly-neutron-absorbing material
International Nuclear Information System (INIS)
Sekine, T.; Baba, H.
1978-01-01
Self-shielding and burn-out effects are discussed in the evaluation of radioisotopes formed by neutron irradiation of a strongly-neutron-absorbing material. A method of the evaluation of such effects is developed both for thermal and epithermal neutrons. Gadolinium oxide uniformly mixed with graphite powder was irradiated by reactor-neutrons together with pieces of a Co-Al alloy wire (the content of Co being 0.475%) as the neutron flux monitor. The configuration of the samples and flux monitors in each of two irradiations is illustrated. The yields of activities produced in the irradiated samples were determined by the γ-spectrometry with a Ge(Li) detector of a relative detection efficiency of 8%. Activities at the end of irradiation were estimated by corrections due to pile-up, self-absorption, detection efficiency, branching ratio, and decay of the activity. Results of the calculation are discussed in comparison with the observed yields of 153 Gd, 160 Tb, and 161 Tb for the case of neutron irradiation of disc-shaped targets of gadolinium oxide. (T.G.)
Strong Quantum Confinement Effects and Chiral Excitons in Bio-Inspired ZnO–Amino Acid Cocrystals
Muhammed, Madathumpady Abubaker Habeeb
2018-02-20
Elucidating the underlying principles behind band gap engineering is paramount for the successful implementation of semiconductors in photonic and optoelectronic devices. Recently it has been shown that the band gap of a wide and direct band gap semiconductor, such as ZnO, can be modified upon cocrystallization with amino acids, with the role of the biomolecules remaining unclear. Here, by probing and modeling the light-emitting properties of ZnO-amino acid cocrystals, we identify the amino acids\\' role on this band gap modulation and demonstrate their effective chirality transfer to the interband excitations in ZnO. Our 3D quantum model suggests that the strong band edge emission blue-shift in the cocrystals can be explained by a quasi-periodic distribution of amino acid potential barriers within the ZnO crystal lattice. Overall, our findings indicate that biomolecule cocrystallization can be used as a truly bio-inspired means to induce chiral quantum confinement effects in quasi-bulk semiconductors.
Kahn-Horwitz, Janina; Shimron, Joseph; Sparks, Richard L
2006-06-01
This study examined individual differences among beginning readers of English as a foreign language (EFL). The study concentrated on the effects of underlying first language (L1) knowledge as well as EFL letter and vocabulary knowledge. Phonological and morphological awareness, spelling, vocabulary knowledge, and word reading in Hebrew L1, in addition to knowledge of EFL letters and EFL vocabulary, were measured. The study also investigated the effect of socioeconomic background (SES) on beginning EFL readers. Participants included 145 fourth graders from three schools representing two socioeconomic backgrounds in the north of Israel. The results indicate that knowledge of English letters played a more prominent role than knowledge of Hebrew L1 components in differentiating between strong and weak EFL readers. The Linguistic Coding Differences Hypothesis was supported by L1 phonological awareness, word reading, and vocabulary knowledge appearing as part of discriminating functions. The presence of English vocabulary knowledge as part of the discriminant functions provides support for English word reading being more than just a decoding task for EFL beginner readers. Socioeconomic status differentiated the groups for EFL word recognition but not for EFL reading comprehension.
Directory of Open Access Journals (Sweden)
Howard Barbara V
2008-10-01
Full Text Available Abstract Background Body fat mass distribution and deposition are determined by multiple environmental and genetic factors. Obesity is associated with insulin resistance, hyperinsulinemia, and type 2 diabetes. We previously identified evidence for genotype-by-diabetes interaction on obesity traits in Strong Heart Family Study (SHFS participants. To localize these genetic effects, we conducted genome-wide linkage scans of obesity traits in individuals with and without type 2 diabetes, and in the combined sample while modeling interaction with diabetes using maximum likelihood methods (SOLAR 2.1.4. Methods SHFS recruited American Indians from Arizona, North and South Dakota, and Oklahoma. Anthropometric measures and diabetes status were obtained during a clinic visit. Marker allele frequencies were derived using maximum likelihood methods estimated from all individuals and multipoint identity by descent sharing was estimated using Loki. We used variance component linkage analysis to localize quantitative trait loci (QTLs influencing obesity traits. We tested for evidence of additive and QTL-specific genotype-by-diabetes interactions using the regions identified in the diabetes-stratified analyses. Results Among 245 diabetic and 704 non-diabetic American Indian individuals, we detected significant additive gene-by-diabetes interaction for weight and BMI (P P Conclusion These results suggest distinct genetic effects on body mass in individuals with diabetes compared to those without diabetes, and a possible role for one or more genes on chromosome 1 in the pathogenesis of obesity.
International Nuclear Information System (INIS)
Alnaser, A S; Maharjan, C M; Wang, P; Litvinyuk, I V
2006-01-01
We studied ionization of neon and argon by intense linearly polarized femtosecond laser pulses of different wavelengths (400 nm and 800 nm) and peak intensities, and by measuring momentum distributions of singly charged positive ions in the direction parallel to laser polarization. For Ne the momentum distributions exhibited a characteristic dip at zero momentum at 800 nm and a complex multipeak structure at 400 nm. Similarly, for Ar the momentum distributions evolved from a complex multipeak structure with a pronounced dip in the centre at 400 nm, to a smooth distribution characteristic of pure tunneling ionization (800 nm, high intensities). In the intermediate regime (800 nm, medium to low intensities), for both atoms we observed recoil ion momentum distributions modulated by quasi-periodic structures usually seen in the photoelectron energy spectra in a multi-photon regime (ATI spectra). Ne did show a characteristic 'dip' at low momentum, while the longitudinal momentum distribution for Ar exhibited a spike at zero momentum instead. The spectra did dramatically change at 400 nm, where both ions show the pronounced dip near zero momentum. Based on our results, we conclude that the structures observed in Ne and Ar momentum distributions reflect the specifics of atomic structure of the two targets and should not be attributed to effects of electron recollision, as was suggested earlier. Instead, as our results indicate, they are due to the effects of multi-photon resonant enhancement of strong-field ionization. (letter to the editor)
Joubert-Doriol, Loïc; Izmaylov, Artur F.
2018-03-01
A new methodology of simulating nonadiabatic dynamics using frozen-width Gaussian wavepackets within the moving crude adiabatic representation with the on-the-fly evaluation of electronic structure is presented. The main feature of the new approach is the elimination of any global or local model representation of electronic potential energy surfaces; instead, the electron-nuclear interaction is treated explicitly using the Gaussian integration. As a result, the new scheme does not introduce any uncontrolled approximations. The employed variational principle ensures the energy conservation and leaves the number of electronic and nuclear basis functions as the only parameter determining the accuracy. To assess performance of the approach, a model with two electronic and two nuclear spacial degrees of freedom containing conical intersections between potential energy surfaces has been considered. Dynamical features associated with nonadiabatic transitions and nontrivial geometric (or Berry) phases were successfully reproduced within a limited basis expansion.
DEFF Research Database (Denmark)
Bak, Keld L.; Jørgensen, Poul; Jensen, H.J.A.
1992-01-01
A new scheme for obtaining first-order nonadiabatic coupling matrix elements (FO-NACME) for multiconfigurational self-consistent-field (MCSCF) wave functions is presented. The FO-NACME are evaluated from residues of linear response functions. The residues involve the geometrical response of a ref......A new scheme for obtaining first-order nonadiabatic coupling matrix elements (FO-NACME) for multiconfigurational self-consistent-field (MCSCF) wave functions is presented. The FO-NACME are evaluated from residues of linear response functions. The residues involve the geometrical response...... to the full configuration interaction limit. Comparisons are made with state-averaged MCSCF results for MgH2 and finite-difference configuration interaction by perturbation with multiconfigurational zeroth-order wave function reflected by interactive process (CIPSI) results for BH....
Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.
Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong
2016-11-30
The effects of strong interactions between Ti and ceria on the structures of Ti/CeO 2 (111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO 2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO 2 (111) to form surface TiO x species, instead of aggregating to form Ti metal clusters for the Ti-CeO 2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti 4+ ions if they are monatomically dispersed on the next near hollow sites of CeO 2 (111) (xTi-NN-hollow); while Ti 3+ ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti 3+ ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti 3+ ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti 3+ ions, or oxidation by O 2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO 2 system by Ti 3+ oxidation. Correspondingly, surface TiO 2 -like species form. This work sheds light into the structures of metal/CeO 2 catalysts with strong interactions between the metal and the ceria support.
Janssens, Lizanne; Stoks, Robby
2013-01-01
Interactions between pollutants and suboptimal environmental conditions can have severe consequences for the toxicity of pollutants, yet are still poorly understood. To identify patterns across environmental conditions and across fitness-related variables we exposed Enallagma cyathigerum damselfly larvae to the pesticide chlorpyrifos at two food levels or at two temperatures and quantified four fitness-related variables (larval survival, development time, mass at emergence and adult cold resistance). Food level and temperature did not affect survival in the absence of the pesticide, yet the pesticide reduced survival only at the high temperature. Animals reacted to the pesticide by accelerating their development but only at the high food level and at the low temperature; at the low food level, however, pesticide exposure resulted in a slower development. Chlorpyrifos exposure resulted in smaller adults except in animals reared at the high food level. Animals reared at the low food level and at the low temperature had a higher cold resistance which was not affected by the pesticide. In summary our study highlight that combined effects of exposure to chlorpyrifos and the two environmental conditions (i) were mostly interactive and sometimes even reversed in comparison with the effect of the environmental condition in isolation, (ii) strongly differed depending on the fitness-related variable under study, (iii) were not always predictable based on the effect of the environmental condition in isolation, and (iv) bridged metamorphosis depending on which environmental condition was combined with the pesticide thereby potentially carrying over from aquatic to terrestrial ecosystems. These findings are relevant when extrapolating results of laboratory tests done under ideal environmental conditions to natural communities. PMID:23840819
Directory of Open Access Journals (Sweden)
Lizanne Janssens
Full Text Available Interactions between pollutants and suboptimal environmental conditions can have severe consequences for the toxicity of pollutants, yet are still poorly understood. To identify patterns across environmental conditions and across fitness-related variables we exposed Enallagma cyathigerum damselfly larvae to the pesticide chlorpyrifos at two food levels or at two temperatures and quantified four fitness-related variables (larval survival, development time, mass at emergence and adult cold resistance. Food level and temperature did not affect survival in the absence of the pesticide, yet the pesticide reduced survival only at the high temperature. Animals reacted to the pesticide by accelerating their development but only at the high food level and at the low temperature; at the low food level, however, pesticide exposure resulted in a slower development. Chlorpyrifos exposure resulted in smaller adults except in animals reared at the high food level. Animals reared at the low food level and at the low temperature had a higher cold resistance which was not affected by the pesticide. In summary our study highlight that combined effects of exposure to chlorpyrifos and the two environmental conditions (i were mostly interactive and sometimes even reversed in comparison with the effect of the environmental condition in isolation, (ii strongly differed depending on the fitness-related variable under study, (iii were not always predictable based on the effect of the environmental condition in isolation, and (iv bridged metamorphosis depending on which environmental condition was combined with the pesticide thereby potentially carrying over from aquatic to terrestrial ecosystems. These findings are relevant when extrapolating results of laboratory tests done under ideal environmental conditions to natural communities.
International Nuclear Information System (INIS)
El-Shorbagy, K.H.
2000-07-01
The influence effect of a strong HF electrical field on the excitation of surface waves by an electron beam under the development of instability of low-density electron beam passing through plane relativistic plasma is investigated. Starting from the two fluid plasma model we separate the problem into two parts. The 'temporal' (dynamical) part enables us to find the frequencies and growth rates of unstable waves. This part within the redefinition of natural (eigen) frequencies coincide with the system describing HF suppression of the Buneman instability in a uniform unbounded plasma. Natural frequencies of oscillations and spatial distribution of the amplitude of the self-consistent electrical field are obtained by solving a boundary value problem ('spatial' part) considering a specific spatial distribution of plasma density. Plasma electrons are considered to have a relativistic velocity. It is shown that a HF electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a relativistic plasma waveguide by a low-density electron beam. The region of instability only slightly narrowing and the growth rate decreases by a small parameter and this result has been reduced compared to nonrelativistic plasma. Also, it is found that the plasma electrons have not affected the solution of the space part of the problem. (author)
Foley, B R; Rose, C G; Rundle, D E; Leong, W; Edmands, S
2013-11-01
Detailed studies of the genetics of speciation have focused on a few model systems, particularly Drosophila. The copepod Tigriopus californicus offers an alternative that differs from standard animal models in that it lacks heteromorphic chromosomes (instead, sex determination is polygenic) and has reduced opportunities for sexual conflict, because females mate only once. Quantitative trait loci (QTL) mapping was conducted on reciprocal F2 hybrids between two strongly differentiated populations, using a saturated linkage map spanning all 12 autosomes and the mitochondrion. By comparing sexes, a possible sex ratio distorter was found but no sex chromosomes. Although studies of standard models often find an excess of hybrid male sterility factors, we found no QTL for sterility and multiple QTL for hybrid viability (indicated by non-Mendelian adult ratios) and other characters. Viability problems were found to be stronger in males, but the usual explanations for weaker hybrid males (sex chromosomes, sensitivity of spermatogenesis, sexual selection) cannot fully account for these male viability problems. Instead, higher metabolic rates may amplify deleterious effects in males. Although many studies of standard speciation models find the strongest genetic incompatibilities to be nuclear-nuclear (specifically X chromosome-autosome), we found the strongest deleterious interaction in this system was mito-nuclear. Consistent with the snowball theory of incompatibility accumulation, we found that trigenic interactions in this highly divergent cross were substantially more frequent (>6×) than digenic interactions. This alternative system thus allows important comparisons to studies of the genetics of reproductive isolation in more standard model systems.
Kharfi, F.; Bastuerk, M.; Boucenna, A.
2006-09-01
The characterization of neutron absorbing materials as well as quantification of neutron attenuation through matter is very essential in various fields, namely in shielding calculation. The objective of this work is to describe an experimental procedure to be used for the determination of neutron transmission through different materials. The proposed method is based on the relation between the gray value measured on neutron radiography image and the corresponding inducing neutron beam. For such a purpose, three kinds of materials (in shape of plate) were investigated using thermal neutrons: (1) boron-alloyed stainless steel as strong absorber; (2) copper and steel as fair absorbers and (3) aluminum as weak absorber. This work is not limited to the determination of neutron transmission through matters; it is also spread out to the measure of the surface density of the neutron absorbing elements (ρs) as a function of thickness of neutron absorbing material such as boron-alloyed stainless steel. The beam hardening effect depending on material thickness was also studied using the neutron transmission measurements. A theoretical approach was used to interpret the experimental results. The neutron transmission measurements were performed at the Neutron Radiography and Tomography facility of the Atomic Institute of the Austrian Universities in Vienna. Finally, a Maxwellian neutron distribution of incident neutron beam was used in the theoretical calculations of neutron energy shift in order to compare with experiments results. The obtained experimental results are in a good agreement with the developed theoretical approach.
Feng, Jieling; Li, Ning; Zhang, Zhengtao; Chen, Xi
2017-08-15
Vegetation phenology changes have been widely applied in the disaster risk assessments of the spring dust storms, and vegetation green-up date shifts have a strong influence on dust storms. However, the effect of earlier vegetation green-up dates due to climate warming on the evaluation of dust storms return periods remains an important, but poorly understood issue. In this study, we evaluate the spring dust storm return period (February to June) in Inner Mongolia, Northern China, using 165 observations of severe spring dust storm events from 16 weather stations, and regional vegetation green-up dates as an integrated factor from NDVI (Normalized Difference Vegetation Index), covering a period from 1982 to 2007, by building the bivariate Copula model. We found that the joint return period showed better fitting results than without considering the integrated factor when the actual dust storm return period is longer than 2years. Also, for extremely severe dust storm events, the gap between simulation result and actual return period can be narrowed up to 0.4888years by using integrated factor. Furthermore, the risk map based on the return period results shows that the Mandula, Zhurihe, Sunitezuoqi, Narenbaolige stations are identified as high risk areas. In this study area, land surface is extensively covered by grasses and shrubs, vegetation green-up date can play a significant role in restraining spring dust storm outbreaks. Therefore, we suggest that Copula method can become a useful tool for joint return period evaluation and risk analysis of severe dust storms. Copyright © 2017 Elsevier B.V. All rights reserved.
Efimov, D K
2016-05-18
We consider Penning ionization of Rydberg atom pairs as an Auger-type process induced by the dipole-dipole interaction and employ semiclassical formulae for dipole transitions to calculate the autoionization width as a function of the principal quantum numbers, n d, n i, of both atoms. While for symmetric atom pairs with the well-known increase of the autoionization width with increasing n 0 is obtained, the result for asymmetric pairs is counterintuitive - for a fixed n i of the ionizing atom of the pair, the autoionization width strongly increases with decreasing n d of the de-excited atom. For H Rydberg atoms this increase reaches two orders of magnitude at the maximum of the n d dependence, and the same type of counterintuitive behavior is exhibited also by Na, Rb and Cs atoms. This is a purely quantum-mechanical effect, which points towards existence of optimal (we call them \\'Tom\\' and \\'Jerry\\' for \\'big\\' and \\'small\\') pairs of Rydberg atoms with respect to autoionization efficiency. Building on the model of population redistribution in cold Rydberg gases proposed in [1], we demonstrate that population evolution following the initial laser excitation of Rydberg atoms in state n 0 would eventually lead to the formation of such Tom-Jerry pairs with which feature autoionization widths that are enhanced by several orders of magnitude compared to that of two atoms in the initial laser-excited state n 0. We also show that in the high-density regime of cold Rydberg gas experiments the ionization rate of Tom-Jerry pairs can be substantially larger than the blackbody radiation-induced photoionization rate. © 2016 IOP Publishing Ltd.
Nonadiabatic semiclassical dynamics in the mixed quantum-classical initial value representation
Church, Matthew S.; Hele, Timothy J. H.; Ezra, Gregory S.; Ananth, Nandini
2018-03-01
We extend the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), a semiclassical method for computing real-time correlation functions, to electronically nonadiabatic systems using the Meyer-Miller-Stock-Thoss (MMST) Hamiltonian in order to treat electronic and nuclear degrees of freedom (dofs) within a consistent dynamic framework. We introduce an efficient symplectic integration scheme, the MInt algorithm, for numerical time evolution of the phase space variables and monodromy matrix under the non-separable MMST Hamiltonian. We then calculate the probability of transmission through a curve crossing in model two-level systems and show that MQC-IVR reproduces quantum-limit semiclassical results in good agreement with exact quantum methods in one limit, and in the other limit yields results that are in keeping with classical limit semiclassical methods like linearized IVR. Finally, exploiting the ability of the MQC-IVR to quantize different dofs to different extents, we present a detailed study of the extents to which quantizing the nuclear and electronic dofs improves numerical convergence properties without significant loss of accuracy.
Classical analog for electronic degrees of freedom in nonadiabatic collision processes
International Nuclear Information System (INIS)
Meyer, H.; Miller, W.H.
1979-01-01
It is shown how a formally exact classical analog can be defined for a finite dimensional (in Hilbert space) quantum mechanical system. This approach is then used to obtain a classical model for the electronic degrees of freedom in a molecular collision system, and the combination of this with the usual classical description of the heavy particle (i.e., nuclear) motion provides a completely classical model for the electronic and heavy particle degrees of freedom. The resulting equations of motion are shown to be equivalent to describing the electronic degrees of freedom by the time-dependent Schroedinger equation, the time dependence arising from the classical motion of the nuclei, the trajectory of which is determined by the quantum mechanical average (i.e., Ehrenfest) force on the nuclei. Quantizing the system via classical S-matrix theory is shown to provide a dynamically consistent description of nonadiabatic collision processes; i.e., different electronic transitions have different heavy particle trajectories and, for example, the total energy of the electronic and heavy particle degrees of freedom is conserved. Application of this classical model for the electronic degrees of freedom (plus classical S-matrix theory) to the two-state model problem shows that the approach provides a good description of the electronic dynamics
Non-adiabatic quantum evolution: The S matrix as a geometrical phase factor
Energy Technology Data Exchange (ETDEWEB)
Saadi, Y., E-mail: S_yahiadz@yahoo.fr [Laboratoire de Physique Quantique et Systèmes Dynamiques, Faculté des Sciences, Université Ferhat Abbas de Sétif, Sétif 19000 (Algeria); Maamache, M. [Laboratoire de Physique Quantique et Systèmes Dynamiques, Faculté des Sciences, Université Ferhat Abbas de Sétif, Sétif 19000 (Algeria)
2012-03-19
We present a complete derivation of the exact evolution of quantum mechanics for the case when the underlying spectrum is continuous. We base our discussion on the use of the Weyl eigendifferentials. We show that a quantum system being in an eigenstate of an invariant will remain in the subspace generated by the eigenstates of the invariant, thereby acquiring a generalized non-adiabatic or Aharonov–Anandan geometric phase linked to the diagonal element of the S matrix. The modified Pöschl–Teller potential and the time-dependent linear potential are worked out as illustrations. -- Highlights: ► In this Letter we study the exact quantum evolution for continuous spectra problems. ► We base our discussion on the use of the Weyl eigendifferentials. ► We give a generalized Lewis and Riesenfeld phase for continuous spectra. ► This generalized phase or Aharonov–Anandan geometric phase is linked to the S matrix. ► The modified Pöschl–Teller and the linear potential are worked out as illustrations.
Greene, Samuel M; Batista, Victor S
2017-09-12
We introduce the "tensor-train split-operator Fourier transform" (TT-SOFT) method for simulations of multidimensional nonadiabatic quantum dynamics. TT-SOFT is essentially the grid-based SOFT method implemented in dynamically adaptive tensor-train representations. In the same spirit of all matrix product states, the tensor-train format enables the representation, propagation, and computation of observables of multidimensional wave functions in terms of the grid-based wavepacket tensor components, bypassing the need of actually computing the wave function in its full-rank tensor product grid space. We demonstrate the accuracy and efficiency of the TT-SOFT method as applied to propagation of 24-dimensional wave packets, describing the S 1 /S 2 interconversion dynamics of pyrazine after UV photoexcitation to the S 2 state. Our results show that the TT-SOFT method is a powerful computational approach for simulations of quantum dynamics of polyatomic systems since it avoids the exponential scaling problem of full-rank grid-based representations.
Raymond, Neil; Iouchtchenko, Dmitri; Roy, Pierre-Nicholas; Nooijen, Marcel
2018-05-01
We introduce a new path integral Monte Carlo method for investigating nonadiabatic systems in thermal equilibrium and demonstrate an approach to reducing stochastic error. We derive a general path integral expression for the partition function in a product basis of continuous nuclear and discrete electronic degrees of freedom without the use of any mapping schemes. We separate our Hamiltonian into a harmonic portion and a coupling portion; the partition function can then be calculated as the product of a Monte Carlo estimator (of the coupling contribution to the partition function) and a normalization factor (that is evaluated analytically). A Gaussian mixture model is used to evaluate the Monte Carlo estimator in a computationally efficient manner. Using two model systems, we demonstrate our approach to reduce the stochastic error associated with the Monte Carlo estimator. We show that the selection of the harmonic oscillators comprising the sampling distribution directly affects the efficiency of the method. Our results demonstrate that our path integral Monte Carlo method's deviation from exact Trotter calculations is dominated by the choice of the sampling distribution. By improving the sampling distribution, we can drastically reduce the stochastic error leading to lower computational cost.
Hu, D; Hannah, J; Gray, R S; Jablonski, K A; Henderson, J A; Robbins, D C; Lee, E T; Welty, T K; Howard, B V
2000-09-01
To examine the relationship between obesity and lipoprotein profiles and compare the effects of total obesity and central adiposity on lipids/lipoproteins in American Indians. Participants were 773 nondiabetic American Indian women and 739 men aged 45 to 74 years participating in the Strong Heart Study. Total obesity was estimated using body mass index (BMI). Central obesity was measured as waist circumference. Lipoprotein measures included triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein AI (apoAI), and apolipoprotein B (apoB). Partial and canonical correlation analyses were used to examine the associations between obesity and lipids/ lipoproteins. Women were more obese than men in Arizona (median BMI 32.1 vs. 29.2 kg/m2) and South Dakota and North Dakota (28.3 vs. 28.0 kg/m2), but there was no sex difference in waist circumference. Men had higher apoB and lower apoAI levels than did women. In women, when adjusted for center, gender, and age, BMI was significantly related to HDL cholesterol (r = -0.24, p HDL cholesterol (r = -0.23, p correlated with triglycerides (r = 0.30, p correlated with HDL cholesterol (r = -0.35, p HDL cholesterol decreased with waist circumference (r = -0.36, p correlation analysis, waist circumference received a greater weight (0.86) than did BMI (0.17) in women. However, the canonical weights were similar for waist (0.46) and BMI (0.56) in men. Only HDL cholesterol (-1.02) carried greater weight in women, whereas in men, triglycerides (0.50), and HDL cholesterol (-0.64) carried a large amount of weight. All the correlation coefficients between BMI, waist circumference, and the first canonical variable of lipids/lipoproteins or between the individual lipid/lipoprotein variables and the first canonical variable of obesity were smaller in women than in men. Triglycerides and HDL cholesterol showed clinically meaningful changes with BMI and waist circumference in men. All
International Nuclear Information System (INIS)
Fechner, Peer Cornelis
2015-01-01
The central topic of this thesis is the experimental observation and the theoretical modeling of non-adiabatic three-body dissociation of H_3 and D_3 neutral triatomic hydrogen molecules. Our goal is to lend a meaning to the observed momentum vector correlation (MVC) of the three emerging ground state hydrogen atoms, for example H_3→H(1s)+H(1s)+H(1s), in terms of symmetries of the nuclear molecular wave function and of the non-adiabatic coupling which initiates this decay. In many experiments carried out over the years, a wealth of state specific MVCs was collected by different research groups. The MVCs are imaged in form of so-called Dalitz plots which show a rich structure of maxima and nodal lines, depending on the initial state of the triatomic hydrogen neutral. Theory was slow to catch up with experiment and only by this year, 2015, a general agreement was accomplished. Nevertheless, these models lack of an easy understanding of the underlying physics as many numerical calculations are involved. The theoretical model presented in this thesis follows a different approach which is more guided by the imaging character of our experiments. We concentrate on a rather qualitative treatment by limiting ourselves to the essential ingredients only. This proceeding contributes to giving a physical interpretation of the structures in the Dalitz plots in the following form: Three-particle coincident imaging offers a direct view of the emerging spatial continuum wave function of a predissociating triatomic molecule as it evolves from molecular spatial dimensions into the realm of independent free particles. This latter result is discussed in the context of the so-called Imaging Theorem, the second main part of this work. A third major part of this thesis pertains to obtaining molecular momentum wave functions in separated degrees-of-freedom via Fourier transformation. Even for triatomic hydrogen - the most simple polyatomic molecule - this is a challenging task. The
PANNEMAN, HJ; BEENACKERS, AACM
1992-01-01
The liquid-phase hydration of cyclohexene, a pseudo first order reversible reaction catalyzed by a strong acid ion exchange resin, macroporous Amberlite XE 307, was investigated in solvent mixtures of water and sulfolane. A decrease by a factor of 3 and 6 is observed in the experimentally measured
Energy Technology Data Exchange (ETDEWEB)
Popov, K I; Rodaljevic, Z P; Krstajic, N V; Novakovic, S D
1985-07-01
It is shown that the improvement in the quality of electrodeposits obtained from CdSO/sub 4/ solution in the presence of strongly adsorbed species compared with that of deposits obtained in the absence of such species is due to a decrease in the exchange current density and an increase in the Tafel slope for the deposition process in the former case.
Energy Technology Data Exchange (ETDEWEB)
Su, Fang [Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Kavli Institute for Theoretical Physics China, Institute of Theoretical Physics, Beijing (China); Huazhong Normal University, Institute of Particle Physics, Wuhan, Hubei (China); Wu, Yue-Liang; Zhuang, Ci [Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Kavli Institute for Theoretical Physics China, Institute of Theoretical Physics, Beijing (China); Yang, Yi-Bo [Chinese Academy of Sciences, State Key Laboratory of Theoretical Physics, Kavli Institute for Theoretical Physics China, Institute of Theoretical Physics, Beijing (China); Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)
2012-03-15
We provide a systematic study of charmless B{sub s}{yields}PP, PV, VV decays (P and V denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent with the results of QCD sum-rule calculations. By taking into account important classes of power corrections involving ''chirally enhanced'' terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present predictions for the branching ratios and CP asymmetries of B{sub s} decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the symmetry relations are generally respected. (orig.)
Hatzell, Marta C.; Raju, Muralikrishna; Watson, Valerie J.; Stack, Andrew G.; van Duin, Adri C. T.; Logan, Bruce E.
2014-01-01
© 2014 American Chemical Society. The amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10^{-5}) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g^{-1}) had a positive rise potential of 59 ± 4 mV in the LC solution, whereas the carbon with the highest concentration (0.36 mmol g^{-1}) had a negative rise potential (-31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to -6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. These results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.
Hatzell, Marta C.
2014-12-02
© 2014 American Chemical Society. The amount of salinity-gradient energy that can be obtained through capacitive mixing based on double layer expansion depends on the extent the electric double layer (EDL) is altered in a low salt concentration (LC) electrolyte (e.g., river water). We show that the electrode-rise potential, which is a measure of the EDL perturbation process, was significantly (P = 10^{-5}) correlated to the concentration of strong acid surface functional groups using five types of activated carbon. Electrodes with the lowest concentration of strong acids (0.05 mmol g^{-1}) had a positive rise potential of 59 ± 4 mV in the LC solution, whereas the carbon with the highest concentration (0.36 mmol g^{-1}) had a negative rise potential (-31 ± 5 mV). Chemical oxidation of a carbon (YP50) using nitric acid decreased the electrode rise potential from 46 ± 2 mV (unaltered) to -6 ± 0.5 mV (oxidized), producing a whole cell potential (53 ± 1.7 mV) that was 4.4 times larger than that obtained with identical electrode materials (from 12 ± 1 mV). Changes in the EDL were linked to the behavior of specific ions in a LC solution using molecular dynamics and metadynamics simulations. The EDL expanded in the LC solution when a carbon surface (pristine graphene) lacked strong acid functional groups, producing a positive-rise potential at the electrode. In contrast, the EDL was compressed for an oxidized surface (graphene oxide), producing a negative-rise electrode potential. These results established the linkage between rise potentials and specific surface functional groups (strong acids) and demonstrated on a molecular scale changes in the EDL using oxidized or pristine carbons.
Energy Technology Data Exchange (ETDEWEB)
Oldenburg, C.M.; Pruess, K. [Lawrence Berkeley Laboratory, Berkeley, CA (United States)
1995-03-01
We have developed TOUGH2 modules for strongly coupled flow and transport that include full hydrodynamic dispersion. T2DM models tow-dimensional flow and transport in systems with variable salinity, while T32DMR includes radionuclide transport with first-order decay of a parent-daughter chain of radionuclide components in variable salinity systems. T2DM has been applied to a variety of coupled flow problems including the pure solutal convection problem of Elder and the mixed free and forced convection salt-dome flow problem. In the Elder and salt-dome flow problems, density changes of up to 20% caused by brine concentration variations lead to strong coupling between the velocity and brine concentration fields. T2DM efficiently calculates flow and transport for these problems. We have applied T2DMR to the dispersive transport and decay of radionuclide tracers in flow fields with permeability heterogeneities and recirculating flows. Coupling in these problems occurs by velocity-dependent hydrodynamic dispersion. Our results show that the maximum daughter species concentration may occur fully within a recirculating or low-velocity region. In all of the problems, we observe very efficient handling of the strongly coupled flow and transport processes.
Strongly disordered superconductors
International Nuclear Information System (INIS)
Muttalib, K.A.
1982-01-01
We examine some universal effects of strong non-magnetic disorder on the electron-phonon and electron-electron interactions in a superconductor. In particular we explicitly take into account the effect of slow diffusion of electrons in a disordered medium by working in an exact impurity eigenstate representation. We find that the normal diffusion of electrons characterized by a constant diffusion coefficient does not lead to any significant correction to the electron-phonon or the effective electron-electron interactions in a superconductor. We then consider sufficiently strong disorder where Anderson localization of electrons becomes important and determine the effect of localization on the electron-electron interactions. We find that due to localization, the diffusion of electrons becomes anomalous in the sense that the diffusion coefficient becomes scale dependent. This results in an increase in the effective electron-electron interaction with increasing disorder. We propose that this provides a natural explanation for the unusual sensitivity of the transition temperature T/sub c/ of the high T/sub c/ superconductors (T/sub c/ > 10 0 K) to damage effects
The role of magnetic field fluctuations in nonadiabatic acceleration of ions during dipolarization
Ono, Y.; Nosé, M.; Christon, S. P.; Lui, A. T. Y.
2009-05-01
We statistically examine changes in the composition of two different ion species, proton and oxygen ions, in the near-Earth plasma sheet (X = -16 R E ˜ -6 R E ) during substorm-associated dipolarization. We use 10 years of energetic (9-212 keV/e) ion data obtained by the suprathermal ion composition spectrometer (STICS) sensor of the energetic particles and ion composition (EPIC) instrument on board the Geotail spacecraft. The results are as follows: (1) Although the percentage increase in the energy density of O+ ions before and after a dipolarization exceeds that of H+ ions in the low-energy range (9-36 keV/e), this property is not evident in the high-energy range (56-212 keV/e); (2) the energy spectrum of H+ and that of O+ become harder after dipolarization in almost all events; and (3) in some events the energy spectrum of O+ becomes harder than that of H+ as reported by previous studies, and, importantly, in other events, the spectrum of H+ becomes harder than that of O+. In order to investigate what mechanism causes these observational results, we focus on magnetic field fluctuations during dipolarization. It is found that the increase of the spectrum slope is positively correlated with the power of waves whose frequencies are close to the gyrofrequency of H+ or O+, respectively (the correlation coefficient is 0.48 for H+ and 0.68 for O+). In conclusion, ions are nonadiabatically accelerated by the electric field induced by the magnetic field fluctuations whose frequencies are close to their gyrofrequencies.
Mandal, Anirban; Hunt, Katharine L. C.
2018-05-01
For a perturbed quantum system initially in the ground state, the coefficient ck(t) of excited state k in the time-dependent wave function separates into adiabatic and nonadiabatic terms. The adiabatic term ak(t) accounts for the adjustment of the original ground state to form the new ground state of the instantaneous Hamiltonian H(t), by incorporating excited states of the unperturbed Hamiltonian H0 without transitions; ak(t) follows the adiabatic theorem of Born and Fock. The nonadiabatic term bk(t) describes excitation into another quantum state k; bk(t) is obtained as an integral containing the time derivative of the perturbation. The true transition probability is given by |bk(t)|2, as first stated by Landau and Lifshitz. In this work, we contrast |bk(t)|2 and |ck(t)|2. The latter is the norm-square of the entire excited-state coefficient which is used for the transition probability within Fermi's golden rule. Calculations are performed for a perturbing pulse consisting of a cosine or sine wave in a Gaussian envelope. When the transition frequency ωk0 is on resonance with the frequency ω of the cosine wave, |bk(t)|2 and |ck(t)|2 rise almost monotonically to the same final value; the two are intertwined, but they are out of phase with each other. Off resonance (when ωk0 ≠ ω), |bk(t)|2 and |ck(t)|2 differ significantly during the pulse. They oscillate out of phase and reach different maxima but then fall off to equal final values after the pulse has ended, when ak(t) ≡ 0. If ωk0 ω. While the transition probability is rising, the midpoints between successive maxima and minima fit Gaussian functions of the form a exp[-b(t - d)2]. To our knowledge, this is the first analysis of nonadiabatic transition probabilities during a perturbing pulse.
Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces
DEFF Research Database (Denmark)
Hall, B.; Deumens, E.; Ohrn, Y.
2014-01-01
A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...
International Nuclear Information System (INIS)
He Feng; Becker, Andreas; Thumm, Uwe
2008-01-01
We show that the electronic dynamics in a molecule driven by a strong field is complex and potentially even counterintuitive. As a prototype example, we simulate the interaction of a dissociating H 2 + molecule with an intense infrared laser pulse. Depending on the laser intensity, the direction of the electron's motion between the two nuclei is found to follow or oppose the classical laser-electric force. We explain the sensitive dependence of the correlated electronic-nuclear motion in terms of the diffracting electronic momentum distribution of the dissociating two-center system. The distribution is dynamically modulated by the nuclear motion and periodically shifted in the oscillating infrared electric field
Aerts, R; Callaghan, T V; Dorrepaal, E; van Logtestijn, R S P; Cornelissen, J H C
2012-11-01
Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.
Luo, Sizuo; Zhou, Shushan; Hu, Wenhui; Li, Xiaokai; Ma, Pan; Yu, Jiaqi; Zhu, Ruihan; Wang, Chuncheng; Liu, Fuchun; Yan, Bing; Liu, Aihua; Yang, Yujun; Guo, Fuming; Ding, Dajun
2017-12-01
Controlling the molecular axis offers additional ways to study molecular ionization and dissociation in strong laser fields. We measure the ionization and dissociation yields of aligned polar CH3X (X =I , Br) molecules in a linearly polarized femtosecond laser field. The current data show that maximum ionization occurs when the laser polarization is perpendicular to the molecular C -X axis, and dissociation prefers to occur at the laser polarization parallel to the C -X axis. The observed angular distributions suggest that the parent ions are generated by ionization from the HOMO. The angular distribution of fragment ions indicates that dissociation occurs mainly from an ionic excited state produced by ionization from the HOMO-1.
DEFF Research Database (Denmark)
Karhunen, Leila; Lyly, Marika; Lapveteläinen, Anja
2012-01-01
This study aimed to investigate factors associated with weight management, especially whether satiety value of food as a part of a weight-maintenance diet would affect self-regulation of food intake and weight management. Altogether 82 obese subjects completed the study consisting of weight....... However, when regarding all study subjects, success in WM was most strongly associated with a greater increase in the flexible control of eating and experience of greater easiness of WM and control of food intake and a greater decrease in uncontrollable eating and psychological distress. Psychobehavioural......-loss and weight-maintenance (WM) periods. During theWM, subjects were randomized into higher- and lower-satiety food groups. No differences were observed in the changes in body weight, energy intake, or eating behaviour between the groups, even despite the different macronutrient compositions of the diets...
Daněk, J.; Klaiber, M.; Hatsagortsyan, K. Z.; Keitel, C. H.; Willenberg, B.; Maurer, J.; Mayer, B. W.; Phillips, C. R.; Gallmann, L.; Keller, U.
2018-06-01
We study strong-field ionization and rescattering beyond the long-wavelength limit of the dipole approximation with elliptically polarized mid-IR laser pulses. Full three-dimensional photoelectron momentum distributions (PMDs) measured with velocity map imaging and tomographic reconstruction revealed an unexpected sharp ridge structure in the polarization plane (2018 Phys. Rev. A 97 013404). This thin line-shaped ridge structure for low-energy photoelectrons is correlated with the ellipticity-dependent asymmetry of the PMD along the beam propagation direction. The peak of the projection of the PMD onto the beam propagation axis is shifted from negative to positive values when the sharp ridge fades away with increasing ellipticity. With classical trajectory Monte Carlo simulations and analytical analysis, we study the underlying physics of this feature. The underlying physics is based on the interplay between the lateral drift of the ionized electron, the laser magnetic field induced drift in the laser propagation direction, and Coulomb focusing. To apply our observations to emerging techniques relying on strong-field ionization processes, including time-resolved holography and molecular imaging, we present a detailed classical trajectory-based analysis of our observations. The analysis leads to the explanation of the fine structure of the ridge and its non-dipole behavior upon rescattering while introducing restrictions on the ellipticity. These restrictions as well as the ionization and recollision phases provide additional observables to gain information on the timing of the ionization and recollision process and non-dipole properties of the ionization process.
Loi, Shyeh Tjing; Papaloizou, John C. B.
2018-04-01
The spectrum of oscillation modes of a star provides information not only about its material properties (e.g. mean density), but also its symmetries. Spherical symmetry can be broken by rotation and/or magnetic fields. It has been postulated that strong magnetic fields in the cores of some red giants are responsible for their anomalously weak dipole mode amplitudes (the "dipole dichotomy" problem), but a detailed understanding of how gravity waves interact with strong fields is thus far lacking. In this work, we attack the problem through a variety of analytical and numerical techniques, applied to a localised region centred on a null line of a confined axisymmetric magnetic field which is approximated as being cylindrically symmetric. We uncover a rich variety of phenomena that manifest when the field strength exceeds a critical value, beyond which the symmetry is drastically broken by the Lorentz force. When this threshold is reached, the spatial structure of the g-modes becomes heavily altered. The dynamics of wave packet propagation transitions from regular to chaotic, which is expected to fundamentally change the organisation of the mode spectrum. In addition, depending on their frequency and the orientation of field lines with respect to the stratification, waves impinging on different parts of the magnetised region are found to undergo either reflection or trapping. Trapping regions provide an avenue for energy loss through Alfvén wave phase mixing. Our results may find application in various astrophysical contexts, including the dipole dichotomy problem, the solar interior, and compact star oscillations.
Berchtold, Joachim F; Constable, Peter D; Smith, Geoffrey W; Mathur, Sheerin M; Morin, Dawn E; Tranquilli, William J
2005-01-01
The objectives of this study were to determine the effects of hyperosmotic sodium bicarbonate (HSB) administration on arterial and cerebrospinal fluid (CSF) acid-base balance and cardiovascular function in calves with experimentally induced respiratory and strong ion (metabolic) acidosis. Ten healthy male Holstein calves (30-47 kg body weight) were instrumented under halothane anesthesia to permit cardiovascular monitoring and collection of blood samples and CSE Respiratory acidosis was induced by allowing the calves to spontaneously ventilate, and strong ion acidosis was subsequently induced by i.v. administration of L-lactic acid. Calves were then randomly assigned to receive either HSB (8.4% NaHCO3; 5 ml/kg over 5 minutes, i.v.; n=5) or no treatment (controls, n=5) and monitored for 1 hour. Mixed respiratory and strong ion acidosis was accompanied by increased heart rate, cardiac index, mean arterial pressure, cardiac contractility (maximal rate of change of left ventricular pressure), and mean pulmonary artery pressure. Rapid administration of HSB immediately corrected the strong ion acidosis, transiently increased arterial partial pressure of carbon dioxide (P(CO2)), and expanded the plasma volume. The transient increase in arterial P(CO2) did not alter CSF P(CO2) or induce paradoxical CSF acidosis. Compared to untreated control calves, HSB-treated calves had higher cardiac index and contractility and a faster rate of left ventricular relaxation for 1 hour after treatment, indicating that HSB administration improved myocardial systolic function. We conclude that rapid i.v. administration of HSB provided an effective and safe method for treating strong ion acidosis in normovolemic halothane-anesthetized calves with experimentally induced respiratory and strong ion acidosis. Fear of inducing paradoxical CSF acidosis is not a valid reason for withholding HSB administration in calves with mixed respiratory and strong ion acidosis.
Dvali, Gia
2009-01-01
We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...
Strong-coupling approximations
International Nuclear Information System (INIS)
Abbott, R.B.
1984-03-01
Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures
Kelly, Aaron; Brackbill, Nora; Markland, Thomas E
2015-03-07
In this article, we show how Ehrenfest mean field theory can be made both a more accurate and efficient method to treat nonadiabatic quantum dynamics by combining it with the generalized quantum master equation framework. The resulting mean field generalized quantum master equation (MF-GQME) approach is a non-perturbative and non-Markovian theory to treat open quantum systems without any restrictions on the form of the Hamiltonian that it can be applied to. By studying relaxation dynamics in a wide range of dynamical regimes, typical of charge and energy transfer, we show that MF-GQME provides a much higher accuracy than a direct application of mean field theory. In addition, these increases in accuracy are accompanied by computational speed-ups of between one and two orders of magnitude that become larger as the system becomes more nonadiabatic. This combination of quantum-classical theory and master equation techniques thus makes it possible to obtain the accuracy of much more computationally expensive approaches at a cost lower than even mean field dynamics, providing the ability to treat the quantum dynamics of atomistic condensed phase systems for long times.
Energy Technology Data Exchange (ETDEWEB)
Kelly, Aaron; Markland, Thomas E., E-mail: tmarkland@stanford.edu [Department of Chemistry, Stanford University, Stanford, California 94305 (United States); Brackbill, Nora [Department of Physics, Stanford University, Stanford, California 94305 (United States)
2015-03-07
In this article, we show how Ehrenfest mean field theory can be made both a more accurate and efficient method to treat nonadiabatic quantum dynamics by combining it with the generalized quantum master equation framework. The resulting mean field generalized quantum master equation (MF-GQME) approach is a non-perturbative and non-Markovian theory to treat open quantum systems without any restrictions on the form of the Hamiltonian that it can be applied to. By studying relaxation dynamics in a wide range of dynamical regimes, typical of charge and energy transfer, we show that MF-GQME provides a much higher accuracy than a direct application of mean field theory. In addition, these increases in accuracy are accompanied by computational speed-ups of between one and two orders of magnitude that become larger as the system becomes more nonadiabatic. This combination of quantum-classical theory and master equation techniques thus makes it possible to obtain the accuracy of much more computationally expensive approaches at a cost lower than even mean field dynamics, providing the ability to treat the quantum dynamics of atomistic condensed phase systems for long times.
Energy Technology Data Exchange (ETDEWEB)
Coelho, Eduardo Lenho, E-mail: eduardo.coelho@uva.br [Universidade Veiga de Almeida, 108 Ibituruna St., 20271-020, Rio de Janeiro (Brazil); Chiapparini, Marcelo [Instituto de Física, Universidade do Estado do Rio de Janeiro, 524 São Francisco Xavier St., 20271-020, Rio de Janeiro (Brazil); Negreiros, Rodrigo Picanço [Instituto de Física, Universidade Federal Fluminense, Gal. Milton Tavares de Souza Ave., 24210-346, Rio de Janeiro (Brazil)
2015-12-17
One of the most interesting kind of neutron stars are the pulsars, which are highly magnetized neutron stars with fields up to 10{sup 14} G at the surface. The strength of magnetic field in the center of a neutron star remains unknown. According to the scalar virial theorem, magnetic field in the core could be as large as 10{sup 18} G. In this work we study the influence of strong magnetic fields on the cooling of neutron stars coming from direct Urca process. Direct Urca process is an extremely efficient mechanism for cooling a neutron star after its formation. The matter is described using a relativistic mean-field model at zero temperature with eight baryons (baryon octet), electrons and muons. We obtain the relative population of each species of particles as function of baryon density for different magnetic fields. We calculate numerically the cooling of neutron stars for a parametrized magnetic field and compare the results for the case without a magnetic field.
International Nuclear Information System (INIS)
Swanson, R.L.; Steffen, J.E.; Winckler, J.R.
1986-01-01
During the Echo 5 experiment launched 13 November 1979 from the Poker Flat Research Range (Fairbanks, Alaska), a 0.75 A, 37 keV electron beam was injected both up and down the field line to test the use of optical and X-ray methods to detect the beam as it interacted with the atmosphere below the rocket for both the downward injections (markers) and the upward injected electrons which mirrored at the Southern Hemisphere and returned echoes. The artificial auroral streaks created by the markers were easily visible on the ground TV system but the large intensity of photons produced around the rocket masked any response to the markers by the on-board photometers and X-ray detectors. No echoes were detected with any of the detection systems although the power in some of the upward injections was 7.6 times the power in a detected downward injection thus setting an upper limit on the loss-cone echo flux. The magnitude of the bounce averaged pitch angle diffusion coefficient necessary to explain the lack of observable echoes was found to be 4 x 10 -4 S -1 . It was found that an equatorial wave electric field of 11 mVm -1 would account for the lack of echoes. Such fields should cause strong pitch angle scattering of up to 10 keV natural electrons and thus be consistent with the presence of diffuse aurora on the Echo 5 trajectory. (author)
Effect of strong-column weak-beam design provision on the seismic fragility of RC frame buildings
Surana, Mitesh; Singh, Yogendra; Lang, Dominik H.
2018-04-01
Incremental dynamic analyses are conducted for a suite of low- and mid-rise reinforced-concrete special moment-resisting frame buildings. Buildings non-conforming and conforming to the strong-column weak-beam (SCWB) design criterion are considered. These buildings are designed for the two most severe seismic zones in India (i.e., zone IV and zone V) following the provisions of Indian Standards. It is observed that buildings non-conforming to the SCWB design criterion lead to an undesirable column failure collapse mechanism. Although yielding of columns cannot be avoided, even for buildings conforming to a SCWB ratio of 1.4, the observed collapse mechanism changes to a beam failure mechanism. This change in collapse mechanism leads to a significant increase in the building's global ductility capacity, and thereby in collapse capacity. The fragility analysis study of the considered buildings suggests that considering the SCWB design criterion leads to a significant reduction in collapse probability, particularly in the case of mid-rise buildings.
Directory of Open Access Journals (Sweden)
Ting-Ting Cao
Full Text Available Strongly alkaline electrolyzed water (SAEW was prepared by electrolysis of tap water in a laboratory-made water electrolyzer. The pH of stored SAEW was stable for more than one month. The hardness of the electrolyzed water was 30% lower and the Na(+ concentration was 18% higher than those of the tap water. Silkworm cocoon shells were boiled in pH 11.50 SAEW at a ratio of 1∶40∼80 (W/V for 20 min and the sericin layers around the silk fibroin fibers were removed completely. The tensile properties and thermal decomposition temperature of a single filament of silk fibroin obtained by the SAEW method were almost the same as those for the fiber obtained by the neutral soap, and much higher than those for the fiber obtained by Na2CO3 degumming. The results demonstrate that SAEW is an environmentally friendly and pollution-free silk degumming agent that allows highly efficient, low cost recovery of sericin.
Strong Quantum Confinement Effects and Chiral Excitons in Bio-Inspired ZnO–Amino Acid Cocrystals
Muhammed, Madathumpady Abubaker Habeeb; Lamers, Marlene; Baumann, Verena; Dey, Priyanka; Blanch, Adam J.; Polishchuk, Iryna; Kong, Xiang-Tian; Levy, Davide; Urban, Alexander S.; Govorov, Alexander O.; Pokroy, Boaz; Rodrí guez-Ferná ndez, Jessica; Feldmann, Jochen
2018-01-01
of amino acid potential barriers within the ZnO crystal lattice. Overall, our findings indicate that biomolecule cocrystallization can be used as a truly bio-inspired means to induce chiral quantum confinement effects in quasi-bulk semiconductors.
Strongly interacting Higgs bosons
International Nuclear Information System (INIS)
Appelquist, T.; Bernard, C.
1980-01-01
The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed
Directory of Open Access Journals (Sweden)
Sébastien Chalencon
Full Text Available Competitive swimming as a physical activity results in changes to the activity level of the autonomic nervous system (ANS. However, the precise relationship between ANS activity, fatigue and sports performance remains contentious. To address this problem and build a model to support a consistent relationship, data were gathered from national and regional swimmers during two 30 consecutive-week training periods. Nocturnal ANS activity was measured weekly and quantified through wavelet transform analysis of the recorded heart rate variability. Performance was then measured through a subsequent morning 400 meters freestyle time-trial. A model was proposed where indices of fatigue were computed using Banister's two antagonistic component model of fatigue and adaptation applied to both the ANS activity and the performance. This demonstrated that a logarithmic relationship existed between performance and ANS activity for each subject. There was a high degree of model fit between the measured and calculated performance (R(2=0.84±0.14,p<0.01 and the measured and calculated High Frequency (HF power of the ANS activity (R(2=0.79±0.07, p<0.01. During the taper periods, improvements in measured performance and measured HF were strongly related. In the model, variations in performance were related to significant reductions in the level of 'Negative Influences' rather than increases in 'Positive Influences'. Furthermore, the delay needed to return to the initial performance level was highly correlated to the delay required to return to the initial HF power level (p<0.01. The delay required to reach peak performance was highly correlated to the delay required to reach the maximal level of HF power (p=0.02. Building the ANS/performance identity of a subject, including the time to peak HF, may help predict the maximal performance that could be obtained at a given time.
Flow of CO2 ethanol and of CO2 methanol in a non-adiabatic microfluidic T-junction at high pressures
Blanch Ojea, R.; Tiggelaar, Roald M.; Pallares, J.; Grau, F.X.; Gardeniers, Johannes G.E.
2012-01-01
In this work, an experimental investigation of the single- and multiphase flows of two sets of fluids, CO2–ethanol and CO2–methanol, in a non-adiabatic microfluidic T-junction is presented. The operating conditions ranged from 7 to 18 MPa, and from 294 to 474 K. The feed mass fraction of CO2 in the
International Nuclear Information System (INIS)
Houze, M.
2002-12-01
Thermoelectric power measurement (TEP) is a very potential non destructive evaluation method considered to follow ageing under neutron irradiation of pressure vessel steel of nuclear reactor. Prior to these problems, the aim of this study is to establish correlations between TEP variations and microstructural evolutions of pressure vessel steels during heat treatments. Different steels, permitting to simulate heterogeneities of pressure vessel steels and to deconvoluate main metallurgical phenomenons effects were studied. This work allowed to emphasize effect on TEP of: austenitizing and cooling conditions and therefore of microstructure, metallurgical transformations during tempering (recovery, precipitation of alloying elements), and particularly molybdenum precipitation associated to secondary hardening, residual austenite amount or partial austenitizing. (author)
Bier, R.; Lindberg, T. T.; Wang, S.; Ellis, J. C.; Di Giulio, R. T.; Bernhardt, E. S.
2012-12-01
Surface coal mining is the dominant form of land cover change in northern and central Appalachia. In this process, shallow coal seams are exposed by removing overlying rock with explosives. The resulting fragmented carbonate rock and coal residues are disposed of in stream valleys. These valley fills generate alkaline mine drainage (AlkMD), dramatically increasing alkalinity, ionic strength, substrate supply (esp. SO42-), and trace element (Mn, Li, Se, U) concentrations in downstream rivers as well as significant losses of sensitive fish and macroinvertebrate species. In prior work within the Mud River, which drains the largest surface mine complex in Appalachia, we found that concentrations of AlkMD increase proportionally with the extent of upstream mining. Here we ask "How do stream microbial communities change along this strong chemical gradient?" We collected surface water and benthic biofilms from 25 stream reaches throughout the Mud River spanning the full range of surface mining impacts, with 0-96% of the contributing watershed area converted to surface coal mines. Microbial communities were collected from biofilms grown on a common substrate (red maple veneers) that were incubated in each stream reach for four months prior to collection in April, 2011. 16S rRNA genes from microbial communities at each study site were examined using 454 sequencing and compared with a generalized UniFrac distance matrix (674 sequence eveness) that was used in statistical analyses. Water chemistry at the sites was sampled monthly from July 2010 to December 2010 and again in April 2011. In April, surface water concentrations of SO42-, Ca2+, Mg2+, and Se2- increased linearly with the extent of upstream mining (all regressions R2 >0.43; pPERMANOVA; p=0.029). Bacterial diversity (OTU richness defined at 3% sequence difference) peaked at intermediate conductivities (600 μS cm-1). Environmental data that correlated significantly with the ordination axes were a variety of surface
Wesenbeeck, van B.K.; Mourik, van T.A.; Duivenvoorden, J.F.; Cleef, A.M.
2003-01-01
The effect of a pine plantation on a native subparamo system in the Andes of Colombia (3 100 In above sea level) was studied. The vegetation of an 8 year-old plantation with Pinus patula was compared to that of the surrounding native subparamo. 59 plots made in the subparamo vegetation contained 121
Mettrop, I.S.; Rutte, M.D.; Kooijman, A.M.; Lamers, L.P.M.
2015-01-01
Since the re-establishment of a more natural water regime is considered by water management in wetlands with artificially stable water levels, the biogeochemical and ecological effects of water level fluctuation with different nutrient loads should be investigated. This is particularly important for
Energy Technology Data Exchange (ETDEWEB)
Dopita, Michael A.; Sutherland, Ralph S.; Nicholls, David C.; Kewley, Lisa J.; Vogt, Frédéric P. A., E-mail: Michael.Dopita@anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd., Weston ACT 2611 (Australia)
2013-09-01
Recently, Nicholls et al., inspired by in situ observations of solar system astrophysical plasmas, suggested that the electrons in H II regions are characterized by a κ-distribution of energies rather than a simple Maxwell-Boltzmann distribution. Here, we have collected together new atomic data within a modified photoionization code to explore the effects of both the new atomic data and the κ-distribution on the strong-line techniques used to determine chemical abundances in H II regions. By comparing the recombination temperatures (T {sub rec}) with the forbidden line temperatures (T {sub FL}), we conclude that κ ∼ 20. While representing only a mild deviation from equilibrium, this result is sufficient to strongly influence abundances determined using methods that depend on measurements of the electron temperature from forbidden lines. We present a number of new emission line ratio diagnostics that cleanly separate the two parameters determining the optical spectrum of H II regions—the ionization parameter q or U and the chemical abundance, 12+log(O/H). An automated code to extract these parameters is presented. Using the homogeneous data set from van Zee et al., we find self-consistent results between all of these different diagnostics. The systematic errors between different line ratio diagnostics are much smaller than those found in the earlier strong-line work. Overall, the effect of the κ-distribution on the strong-line abundances derived solely on the basis of theoretical models is rather small.
<strong>Relative Biological Effect of Antiprotonsstrong>> strong>
DEFF Research Database (Denmark)
Bassler, Niels; Holzscheiter, Michael
nuclear research facility CERN. A beam of 126 MeV antiprotons, corresponding to about 12 cm range in water, was spread out to a SOBP with a width of 1 cm. Dosimetry experiments were carried out with ionization chambers, alanine pellets and radiochromic film, and the results were used for benchmarking...
Keren, Yonatan; Borisover, Mikhail; Schaumann, Gabriele E.; Diehl, Dörte; Tamimi, Nisreen; Bukhanovsky, Nadezhda
2017-04-01
Sorption interactions with soils are well known to control the environmental fate of multiple organic compounds including pesticides. Pesticide-soil interactions may be affected by organic amendments or organic matter (OM)-containing wastewater brought to the field. Specifically, land spreading of olive mill wastewater (OMW), occurring intentionally or not, may also influence pesticide-soil interactions. The effects of the OMW disposed in the field on soil properties, including their ability to interact with pesticides, become of great interest due to the increasing demand for olive oil and a constant growth of world oil production. This paper summarizes some recent findings related to the effect of prior OMW land application on the ability of soils to interact with the organic compounds including pesticides, diuron and simazine. The major findings are as following: (1) bringing OMW to the field increases the potential of soils to sorb non-ionized pesticides; (2) this sorption increase may not be related solely to the increase in soil organic carbon content but it can reflect also the changes in the soil sorption mechanisms; (3) increased pesticide interactions with OMW-affected soils may become irreversible, due, assumedly, to the swelling of some components of the OMW-treated soil; (4) enhanced pesticide-soil interactions mitigate with the time passed after the OMW application, however, in the case of diuron, the remaining effect could be envisioned at least 600 days after the normal OMW application; (5) the enhancement effect of OMW application on soil sorption may increase with soil depth, in the 0-10 cm interval; (6) at higher pesticide (diuron) concentrations, larger extents of sorption enhancement, following the prior OMW-soil interactions, may be expected; (7) disposal of OMW in the field may be seasonal-dependent, and, in the case studied, it led to more distinct impacts on sorption when carried out in spring and winter, as compared with summer. It appears
Czech Academy of Sciences Publication Activity Database
Hofmeister, J.; Hošek, J.; Brabec, Marek; Hédl, Radim; Modrý, M.
2013-01-01
Roč. 15, č. 6 (2013), s. 293-303 ISSN 1433-8319 Grant - others:GA MŽP(CZ) SM/6/69/05; GA MŽP(CZ) SP/2D3/139/07 Institutional support: RVO:67985807 ; RVO:67985939 Keywords : ancient forest * edge effect * habitat fragmentation * light condition * soil nutrients * species richness Subject RIV: BB - Applied Statistics, Operational Research; EH - Ecology, Behaviour (BU-J) Impact factor: 3.324, year: 2013
Testing strong interaction theories
International Nuclear Information System (INIS)
Ellis, J.
1979-01-01
The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)
Strong nondipole effects in low-energy photoionization of the 5s and 5p subshells of xenon
International Nuclear Information System (INIS)
Johnson, W. R.; Cheng, K. T.
2001-01-01
Large nondipole effects are predicted in the angular distribution of photoelectrons from the 5s and 5p subshells of xenon for photon energies below 200 eV. The nondipole parameter γ 5s exhibits a dispersion-curve variation near the first minimum of the 5s cross section at 35 eV, reaching a minimum value of -0.8 near 40 eV. Rapid variation of γ 5s is also found near the second minimum of the 5s cross section at 150 eV, where γ 5s reaches a maximum value of 1.2. Smaller, but significant, nondipole effects are also found in the parameter ζ 5p =γ 5p +3δ 5p , which has a maximum value of 0.15 near 50 eV, and a second maximum value of 0.18 near 160 eV. The higher energy maxima in γ 5s and ζ 5p arise from correlation enhanced by shape resonances in the 4p→f quadrupole photoionization channels. These predictions are based on relativistic random-phase approximation calculations in which excitations from 5p, 5s, 4d, 4p, and 4s subshells are coupled
Shao, Qiming
2016-11-18
The electronic and optoelectronic properties of two-dimensional materials have been extensively explored in graphene and layered transition metal dichalcogenides (TMDs). Spintronics in these two-dimensional materials could provide novel opportunities for future electronics, for example, efficient generation of spin current, which should enable the efficient manipulation of magnetic elements. So far, the quantitative determination of charge current-induced spin current and spin-orbit torques (SOTs) on the magnetic layer adjacent to two-dimensional materials is still lacking. Here, we report a large SOT generated by current-induced spin accumulation through the Rashba-Edelstein effect in the composites of monolayer TMD (MoS or WSe)/CoFeB bilayer. The effective spin conductivity corresponding to the SOT turns out to be almost temperature-independent. Our results suggest that the charge-spin conversion in the chemical vapor deposition-grown large-scale monolayer TMDs could potentially lead to high energy efficiency for magnetization reversal and convenient device integration for future spintronics based on two-dimensional materials.
Directory of Open Access Journals (Sweden)
Aurelian Pantea
2013-04-01
Full Text Available In this paper, the macroseismic effects of the subcrustal earthquake in Vrancea (Romania that occurred on March 4, 1977, have been re-evaluated. This was the second strongest seismic event that occurred in this area during the twentieth century, following the event that happened on November 10, 1940. It is thus of importance for our understanding of the seismicity of the Vrancea zone. The earthquake was felt over a large area, which included the territories of the neighboring states, and it produced major damage. Due to its effects, macroseismic studies were developed by Romanian researchers soon after its occurrence, with foreign scientists also involved, such as Medvedev, the founder of the Medvedev-Sponheuer-Karnik (MSK seismic intensity scale. The original macroseismic questionnaires were re-examined, to take into account the recommendations for intensity assessments according to the MSK-64 macroseismic scale used in Romania. After the re-evaluation of the macroseismic field of this earthquake, the intensity dataset was obtained for 1,620 sites in Romanian territory. The re-evaluation was necessary as it has confirmed that the previous macroseismic map was underestimated. On this new map, only the intensity data points are plotted, without tracing the isoseismals.
Song, Juntao; Fine, Carolyn; Prodan, Emil
2014-11-01
The effect of strong disorder on chiral-symmetric three-dimensional lattice models is investigated via analytical and numerical methods. The phase diagrams of the models are computed using the noncommutative winding number, as functions of disorder strength and model's parameters. The localized/delocalized characteristic of the quantum states is probed with level statistics analysis. Our study reconfirms the accurate quantization of the noncommutative winding number in the presence of strong disorder, and its effectiveness as a numerical tool. Extended bulk states are detected above and below the Fermi level, which are observed to undergo the so-called "levitation and pair annihilation" process when the system is driven through a topological transition. This suggests that the bulk invariant is carried by these extended states, in stark contrast with the one-dimensional case where the extended states are completely absent and the bulk invariant is carried by the localized states.
Berezhkovskii, Alexander M.; Bezrukov, Sergey M.
2017-08-01
Ligand- or voltage-driven stochastic gating—the structural rearrangements by which the channel switches between its open and closed states—is a fundamental property of biological membrane channels. Gating underlies the channel's ability to respond to different stimuli and, therefore, to be functionally regulated by the changing environment. The accepted understanding of the gating effect on the solute flux through the channel is that the mean flux is the product of the flux through the open channel and the probability of finding the channel in the open state. Here, using a diffusion model of channel-facilitated transport, we show that this is true only when the gating is much slower than the dynamics of solute translocation through the channel. If this condition breaks, the mean flux could differ from this simple estimate by orders of magnitude.
Strong crystal field effect in Np{sup 4+}:ThCl{sub 4} - optical absorption study
Energy Technology Data Exchange (ETDEWEB)
Gajek, Z. [Instytut Niskich Temperatur i Badan Strukturalnych, Polska Akademia Nauk, 50-950 Wroclaw 2, Skr. Poczt. 1410 (Poland); Krupa, J.C. [Laboratoire de Radiochimie, Institut de Physique Nucleaire, BP 1, 91406 Orsay Cedex (France)
1998-12-21
Results of optical absorption measurements in polarized light on tetravalent neptunium diluted in a ThCl{sub 4} single crystal are reported. The recorded spectra are complex, pointing to the presence of an Np{sup 3+} impurity. The electronic transitions assigned to the Np{sup 4+} ion are interpreted in terms of the usual model, following the actual understanding of the neptunium electronic structure and independent theoretical predictions. R.m.s. deviations of the order of 36 cm{sup -1} have been obtained for 42 levels fitted with 11 free parameters. The crystal field effect resulting from the fitting is considerably larger than that observed for the uranium ion in the same host. (author)
Strong anisotropy effect in an iron-based superconductor CaFe0.882Co0.118AsF
Ma, Yonghui; Ji, Qiucheng; Hu, Kangkang; Gao, Bo; Li, Wei; Mu, Gang; Xie, Xiaoming
2017-07-01
The anisotropy of iron-based superconductors is much smaller than that of the cuprates and that predicted by theoretical calculations. A credible understanding for this experimental fact is still lacking up to now. Here we experimentally study the magnetic-field-angle dependence of electronic resistivity in the superconducting phase of an iron-based superconductor CaFe{}0.882Co{}0.118AsF, and find the strongest anisotropy effect of the upper critical field among the iron-based superconductors based on the framework of Ginzburg-Landau theory. The evidence of the energy band structure and charge density distribution from electronic structure calculations demonstrates that the observed strong anisotropic effect mainly comes from the strong ionic bonding in between the ions of Ca2+ and F-, which weakens the interlayer coupling between the layers of FeAs and CaF. This finding provides a significant insight into the nature of the experimentally-observed strong anisotropic effect of electronic resistivity, and also paves the way for designing exotic two-dimensional artificial unconventional superconductors in the future.
International Nuclear Information System (INIS)
Stevenson, J.D.
1995-11-01
Since 1982, there has been a major effort expended to evaluate the susceptibility of nuclear Power plant equipment to failure and significant damage during seismic events. This was done by making use of data on the performance of electrical and mechanical equipment in conventional power plants and other similar industrial facilities during strong motion earthquakes. This report is intended as an extension of the seismic experience data collection effort and a compilation of experience data specific to power plant piping and supports designed and constructed US power piping code requirements which have experienced strong motion earthquakes. Eight damaging (Richter Magnitude 7.7 to 5.5) California earthquakes and their effects on 8 power generating facilities in use natural gas and California were reviewed. All of these facilities were visited and evaluated. Seven fossel-fueled (dual use natural gas and oil) and one nuclear fueled plants consisting of a total of 36 individual boiler or reactor units were investigated. Peak horizontal ground accelerations that either had been recorded on site at these facilities or were considered applicable to these power plants on the basis of nearby recordings ranged between 0.20g and 0.5lg with strong motion durations which varied from 3.5 to 15 seconds. Most US nuclear power plants are designed for a safe shutdown earthquake peak ground acceleration equal to 0.20g or less with strong motion durations which vary from 10 to 15 seconds
Taherian, Fatemeh; Vafaei, Abbas Ali; Vaezi, Gholam Hassan; Eskandarian, Sharaf; Kashef, Adel; Rashidy-Pour, Ali
2014-01-01
Introduction Previous studies have demonstrated that the β-adrenergic receptor antagonist propranolol impairs fear memory reconsolidation in experimental animals. There are experimental parameters such as the age and the strength of memory that can interact with pharmacological manipulations of memory reconsolidation. In this study, we investigated the ability of the age and the strength of memory to influence the disrupting effects of propranolol on fear memory reconsolidation in rats. Methods The rats were trained in a contextual fear conditioning using two (weak training) or five (strong training) footshocks (1mA). Propranolol (10mg/kg) injection was immediately followed retrieval of either a one-day recent (weak or strong) or 36-day remote (weak or strong) contextual fear memories. Results We found that propranolol induced a long-lasting impairment of subsequent expression of recent and remote memories with either weak or strong strength. We also found no memory recovery after a weak reminder shock. Furthermore, no significant differences were found on the amount of memory deficit induced by propranolol among memories with different age and strength. Discussion Our data suggest that the efficacy of propranolol in impairing fear memory reconsolidation is not limited to the age or strength of the memory. PMID:25337385
Energy Technology Data Exchange (ETDEWEB)
Mochalov, M. A., E-mail: postmaster@ifv.vniief.ru; Il’kaev, R. I. [Russian Federal Nuclear Center All-Russia Research Institute for Nuclear Physics (Russian Federation); Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Mikhailov, A. L.; Blikov, A. O.; Ogorodnikov, V. A. [Russian Federal Nuclear Center All-Russia Research Institute for Nuclear Physics (Russian Federation); Gryaznov, V. K. [Russian Academy of Sciences, Institute for Problems of Chemical Physics (Russian Federation); Iosilevskii, I. L. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2017-03-15
We report on the experimental results on the quasi-isentropic compressibility of a strongly nonideal deuterium plasma that have been obtained on setups of cylindrical and spherical geometries in the pressure range of up to P ≈ 5500 GPa. We describe the characteristics of experimental setups, as well as the methods for the diagnostics and interpretation of the experimental results. The trajectory of metal shells that compress the deuterium plasma was detected using powerful pulsed X-ray sources with a maximal electron energy of up to 60 MeV. The values of the plasma density, which varied from ρ ≈ 0.8 g/cm{sup 3} to ρ ≈ 6 g/cm{sup 3}, which corresponds to pressure P ≈ 5500 GPa (55 Mbar), were determined from the measured value of the shell radius at the instant that it was stopped. The pressure of the compressed plasma was determined using gasdynamic calculations taking into account the actual characteristics of the experimental setups. We have obtained a strongly compressed deuterium plasma in which electron degeneracy effects under the conditions of strong interparticle interaction are significant. The experimental results have been compared with the theoretical models of a strongly nonideal partly degenerate plasma. We have obtained experimental confirmation of the plasma phase transition in the pressure range near 150 GPa (1.5 Mbar), which is in keeping with the conclusion concerning anomaly in the compressibility of the deuterium plasma drawn in [1].
Réalis-Doyelle, Emilie; Pasquet, Alain; De Charleroy, Daniel; Fontaine, Pascal; Teletchea, Fabrice
2016-01-01
Temperature is the main abiotic factor that influences the life cycle of poikilotherms. The present study investigated the thermal tolerance and phenotypic plasticity of several parameters (development time, morphometric measures, bioenergetics) for both embryos and fry of a cold stenothermal fish species, brown trout (Salmo trutta L.) in order to allow for a holistic evaluation of the potential effects of temperature. Five temperatures (4°C, 6°C, 8°C, 10°C, and 12°C) were tested, and the effects of temperature were analyzed at three stages: hatching, emergence, and first food intake. A mean of 5,440 (S.E. ± 573) eggs, coming from seven females and seven males (seven families) captured close to Linkebeek (Belgium), were used for each temperature. Maximum survival of well-formed fry at first food intake and better use of energy budget were found at 6°C and 8°C, temperatures at which the possible contribution to the next generation should therefore be greatest. At 12°C, the experimental population fell dramatically (0.9% survival rate for well-formed fry at first food intake), and fry had almost no yolk sac at first food intake. The present results on survival at 12°C are in accordance with predictions of a sharp decrease in brown trout numbers in France over the coming decades according to climate change projections (1°C to 5°C temperature rise by 2100 for France). At 10°C, there was also a lower survival rate (55.4% at first food intake). At 4°C, the survival rate was high (76.4% at first food intake), but the deformity rate was much higher (22% at first food intake) than at 6°C, 8°C, and 10°C. The energetic budget showed that at the two extreme temperatures (4°C and 12°C) there was less energy left in the yolk sac at first food intake, suggesting a limited ability to survive starvation.
Beruto, Dario T; Botter, Rodolfo; Converti, Attilio
2009-02-01
Aluminum hydroxide gels were washed with water, ethanol, methanol and isopropanol to obtain new gels with different liquid phases that were dried either in air at 120 degrees C or under vacuum at 80 degrees C. Drying in air leads to alcoholic xerogels with BET surface areas larger than the aqueous ones. The effect of the alcoholic groups as substitutes of the hydroxyl ones has been discussed to account for the final size of xerogel crystallites. Drying under vacuum decreases the BET surface of the methanol xerogels, but no micropores are formed in all the alcoholic xerogel matrixes. On the contrary, the vacuum drying process changes significantly the microstructure of the aqueous xerogels. Their BET surface increases by 34 m(2)/g, and micropores are formed within their crystallite aggregates. It has been experimentally shown that these changes are due to a shear transformation that occurs in the boehmite xerogels obtained under vacuum. To discuss these data, the existence of chemical compounds such as AlOOHnH(2)O was postulated. On this ground, a neat analogy between vacuum drying process and vacuum interfacial decomposition reactions of inorganic salts can be drawn. This analogy explains how a state of stresses forms in aqueous xerogel matrix during vacuum drying process.
International Nuclear Information System (INIS)
Leppäkangas, J; De Graaf, S E; Adamyan, A; Fogelström, M; Danilov, A V; Kubatkin, S E; Johansson, G; Lindström, T
2013-01-01
We experimentally and theoretically study the frequency shift of a driven cavity coupled to a superconducting charge qubit. In addition to previous studies, here we also consider drive strengths large enough to energetically allow for quasiparticle creation. Quasiparticle tunnelling leads to the inclusion of more than two charge states in the dynamics. To explain the observed effects, we develop a master equation for the microwave dressed charge states, including quasiparticle tunnelling. A bimodal behaviour of the frequency shift as a function of gate voltage can be used for sensitive charge detection. However, at weak drives, the charge sensitivity is significantly reduced by nonequilibrium quasiparticles, which induce transitions to a non-sensitive state. Unexpectedly, at high-enough drives, the quasiparticle tunnelling enables a very fast relaxation channel to the sensitive state. In this regime, the charge sensitivity is thus robust against externally injected quasiparticles and the desired dynamics prevail over a broad range of temperatures. We find very good agreement between the theory and experiment over a wide range of drive strengths and temperatures. (paper)
Ziemann, Frank; Seltzsam, Steve; Dreffke, Kristin; Preising, Stefanie; Arenz, Andrea; Subtil, Florentine S B; Rieckmann, Thorsten; Engenhart-Cabillic, Rita; Dikomey, Ekkehard; Wittig, Andrea
2017-12-01
At present, advanced stage human Papillomavirus (HPV) negative and positive head and neck squamous cell carcinoma (HNSCC) are treated by intense multimodal therapy that includes radiochemotherapy, which are associated with relevant side effects. Patients with HPV positive tumors possess a far better prognosis than those with HPV negative cancers. Therefore, new therapeutic strategies are needed to improve the outcome especially of the latter one as well as quality of life for all HNSCC patients. Here we tested whether roscovitine, an inhibitor of cyclin-dependent kinases (CDKs), which hereby also blocks homologous recombination (HR), can be used to enhance the radiation sensitivity of HNSCC cell lines. In all five HPV negative and HPV positive cell lines tested, roscovitine caused inhibition of CDK1 and 2. Surprisingly, all HPV positive cell lines were found to be defective in HR. In contrast, HPV negative strains demonstrated efficient HR, which was completely suppressed by roscovitine. In line with this, for HPV negative but not for HPV positive cell lines, treatment with roscovitine resulted in a pronounced enhancement of the radiation-induced G2 arrest as well as a significant increase in radiosensitivity. Due to a defect in HR, all HPV positive cell lines were efficiently radiosensitized by the PARP-1 inhibitor olaparib. In contrast, in HPV negative cell lines a significant radiosensitization by olaparib was only achieved when combined with roscovitine.
Xie, Changjian; Guo, Hua
2018-01-01
The choice of the active degrees of freedom (DOFs) is a pivotal issue in a reduced-dimensional model of quantum dynamics when a full-dimensional one is not feasible. Here, several five-dimensional (5D) models are used to investigate the nonadiabatic photodissociation dynamics of the hydroxymethyl (CH2OH) radical, which possesses nine internal DOFs, in its lowest absorption band. A normal-mode based scheme is used to identify the active and spectator modes, and its predictions are confirmed by 5D quantum dynamical calculations. Our results underscore the important role of the CO stretching mode in the photodissociation dynamics of CH2OH, originating from the photo-induced promotion of an electron from the half-occupied π*CO antibonding orbital to a carbon Rydberg orbital.
International Nuclear Information System (INIS)
Olaniyi, B.; Shor, A.; Cheng, S.C.; Dugan, G.; Wu, C.S.
1981-05-01
The effective quadrupole moments Q sub(eff) of the nuclei of 165 Ho, 175 Lu, 176 Lu, 179 Hf and 181 Ta were accurately measured by detecting the pionic atom 5g-4f x-rays of the elements. The spectroscopic quadrupole moments, Q sub(spec), were obtained by correcting Q sub(eff) for nuclear finite size effect, distortion of the pion wave function by the pion-nucleus strong interaction, and contribution to the energy level splittings by the strong interaction. The intrinsic quadrupole moments, Q 0 , were obtained by projecting Q sub(spec) into the frame of reference fixed on the nucleus. The shift, epsilon 0 , and broadening, GAMMA 0 , of the 4f energy level due to the strong interactions between the pion and the nucleons for all the elements were also measured. Theoretical values of epsilon 0 and GAMMA 0 were calculated and compared to the experimental values. The measured values of Q 0 were compared with the existing results in muonic and pionic atoms. The measured values of epsilon 0 and GAMMA 0 were also compared with existing values. (auth)
Probing strong-field electron-nuclear dynamics of polyatomic molecules using proton motion
International Nuclear Information System (INIS)
Markevitch, Alexei N.; Smith, Stanley M.; Levis, Robert J.; Romanov, Dmitri A.
2007-01-01
Proton ejection during Coulomb explosion is studied for several structure-related organic molecules (anthracene, anthraquinone, and octahydroanthracene) subjected to 800 nm, 60 fs laser pulses at intensities from 0.50 to 4.0x10 14 W cm -2 . The proton kinetic energy distributions are found to be markedly structure specific. The distributions are bimodal for anthracene and octahydroanthracene and trimodal for anthraquinone. Maximum (cutoff) energies of the distributions range from 50 eV for anthracene to 83 eV for anthraquinone. The low-energy mode (∼10 eV) is most pronounced in octahydroanthracene. The dependence of the characteristic features of the distributions on the laser intensity provides insights into molecular specificity of such strong-field phenomena as (i) nonadiabatic charge localization and (ii) field-mediated restructuring of polyatomic molecules polarized by a strong laser field
PANNEMAN, HJ; BEENACKERS, AACM
The liquid-phase hydration of cyclohexene, a pseudo-first-order reversible reaction catalyzed by a strong acid ion-exchange resin, was investigated in solvent mixtures of water and sulfolane. Macroporous Amberlite XE 307 was used because of its superior catalytic activity. Chemical equilibrium
PANNEMAN, HJ; BEENACKERS, AACM
The kinetics of the' hydration of cyclohexene, catalyzed by a strong acid ion-exchange resin, have been studied in a packed bed reactor at temperatures between 353 and 413 K and a pressure of 20 bar. The kinetic rate constants were measured as a function of temperature and solvent composition (0-90
Abortion: Strong's counterexamples fail
DEFF Research Database (Denmark)
Di Nucci, Ezio
2009-01-01
This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally...
International Nuclear Information System (INIS)
Goldman, M.V.
1984-01-01
After a brief discussion of beam-excited Langmuir turbulence in the solar wind, we explain the criteria for wave-particle, three-wave and strong turbulence interactions. We then present the results of a numerical integration of the Zakharov equations, which describe the strong turbulence saturation of a weak (low-density) high energy, bump-on-tail beam instability. (author)
Troost, Joachim; Tatami, Shinji; Tsuda, Yasuhiro; Mattheus, Michaela; Mehlburger, Ludwig; Wein, Martina; Michel, Martin C
2011-01-01
AIM To determine the effect of the strong CYP2D6 inhibitor paroxetine and strong CYP3A4 inhibitor ketoconazole on the pharmacokinetics and safety (orthostatic challenge) of tamsulosin. METHODS Two open-label, randomized, two-way crossover studies were conducted in healthy male volunteers (extensive CYP2D6 metabolizers). RESULTS Co-administration of multiple oral doses of 20 mg paroxetine once daily with a single oral dose of the 0.4 mg tamsulosin HCl capsule increased the adjusted geometric mean (gMean) values of Cmax and AUC(0,∞) of tamsulosin by factors of 1.34 (90% CI 1.21, 1.49) and 1.64 (90% CI 1.44, 1.85), respectively, and increased the terminal half-life (t1/2) of tamsulosin HCl from 11.4 h to 15.3 h. Co-administration of multiple oral doses of 400 mg ketoconazole once dailywith a single oral dose of the 0.4 mg tamsulosin increased the gMean values of Cmax and AUC(0,∞) of tamsulosin by a factor of 2.20 (90% CI 1.96, 2.45) and 2.80 (90% CI 2.56, 3.07), respectively. The terminal half-life was slightly increased from 10.5 h to 11.8 h. These pharmacokinetic changes were not accompanied by clinically significant alterations of haemodynamic responses during orthostatic stress testing. CONCLUSION The exposure to tamsulosin is increased upon co-administration of strong CYP2D6 inhibitors and even more so of strong 3A4 inhibitors, but neither PK alteration was accompanied by clinically significant haemodynamic changes during orthostatic stress testing. PMID:21496064
<strong>Neuroeconomics and Human Resource Developmentstrong>/>
DEFF Research Database (Denmark)
Larsen, Torben
2009-01-01
Neuroeconomics and Human Resource Development Objective Neuroeconomic game trials have detected a present-bias in human decision making which represents a serious shortcoming facing the long termed nature of complex problems in a globalized economy i.e. regional residual poverty, ecological...... threats and personal stress. So far, the evidence-based findings on human resource development (HRD) seem not to match these huge challenges. The aim of this study is to identify cost-effective means of mental training to recover sufficiently from the present bias to enable more sustainable decisions...... Pragmatic de-stressing by medical meditation adds extra years to a normal life and saves health care expenses for a moderate meditation course fee. So, medical meditation prevails as a dominant de-stressing intervention serving a wider goal of more long termed decision making. An international monitoring...
International Nuclear Information System (INIS)
Nakano, Masayoshi; Kishi, Ryohei; Nitta, Tomoshige; Yamaguchi, Kizashi
2004-01-01
We investigate the relaxation effects on the quantum dynamics in a two-state molecular system interacting with a single-mode strongly amplitude-squeezed coherent field using the second-order Monte Carlo wave-function method. The molecular population inversion (collapse-revival behavior of Rabi oscillations) is known to show the echoes after each revival, which are referred to as ringing revivals, in the case of strongly squeezed coherent fields with oscillatory photon-number distributions due to the phase-space interference effect. Two types of relaxation effects, i.e., cavity relaxation (the dissipation of an internal single mode to outer mode) and molecular coherent (phase) relaxation caused by nuclear vibrations on ringing revivals are investigated from the viewpoint of the quantum-phase dynamics using the quasiprobability (Q function) distribution of a single-mode field and the off-diagonal molecular density matrix ρ elec1,2 (t). It turns out that the molecular phase relaxation attenuates both the entire revival-collapse behavior and the increase in ρ elec1,2 (t) during the quiescent region, whereas a very slight cavity relaxation particularly suppresses the echoes in ringing revivals more significantly than the first revival but hardly changes a primary variation in envelope of ρ elec1,2 (t) in the nonrelaxation case
Balucani, Nadia; Leonori, Francesca; Casavecchia, Piergiorgio; Fu, Bina; Bowman, Joel M
2015-12-17
The combustion relevant O((3)P) + C2H4 reaction stands out as a prototypical multichannel nonadiabatic reaction involving both triplet and singlet potential energy surfaces (PESs), which are strongly coupled. Crossed molecular beam (CMB) scattering experiments with universal soft electron ionization mass spectrometric detection have been used to characterize the dynamics of this reaction at the relatively high collision energy Ec of 13.7 kcal/mol, attained by crossing the reactant beams at an angle of 135°. This work is a full report of the data at the highest Ec investigated for this reaction. From laboratory product angular and velocity distribution measurements, angular and translational energy distributions in the center-of-mass system have been obtained for the five observed exothermic competing reaction channels leading to H + CH2CHO, H + CH3CO, CH3 + HCO, CH2 + H2CO, and H2 + CH2CO. The product branching ratios (BRs) have been derived. The elucidation of the reaction dynamics is assisted by synergic full-dimensional quasiclassical trajectory surface-hopping calculations of the reactive differential cross sections on coupled ab initio triplet/singlet PESs. This joint experimental/theoretical study extends and complements our previous combined CMB and theoretical work at the lower collision energy of 8.4 kcal/mol. The theoretically derived BRs and extent of intersystem crossing (ISC) are compared with experimental results. In particular, the predictions of the QCT results for the three main channels (those leading to vinoxy + H, methyl + HCO and methylene + H2CO formation) are compared directly with the experimental data in the laboratory frame. Good overall agreement is noted between theory and experiment, although some small, yet significant shortcomings of the theoretical differential cross section are noted. Both experiment and theory find almost an equal contribution from the triplet and singlet surfaces to the reaction, with a clear tendency of the
Calculation of decay widths of pp{mu}{sub {nu}}{sub ,J}{sup *} ion in non-adiabatic approach
Energy Technology Data Exchange (ETDEWEB)
Gheisari, R. [Persian Gulf Univ., Physics Dept., Bushehr (Iran, Islamic Republic of)
2009-06-15
We calculate decay widths of the metastable pp{mu}{sub {nu}}{sub ,J}{sup *} molecular ion in non-adiabatic approach. The muonic molecular ion can be formed in collision of the excited p{mu}(2s) atoms with H{sub 2}. Then, the decay of the pp{mu}{sub {nu}}{sub ,J}{sup *} system opens a path for the muon from p{mu}(2s) to p{mu}(1s). We employ trial wave function which includes non-adiabatic terms to calculate some radiationless decay widths. The present results of the widths do not agree well with those given in our previous work, however they are more close to recent data of other researchers. (author)
Bitcoin Meets Strong Consistency
Decker, Christian; Seidel, Jochen; Wattenhofer, Roger
2014-01-01
The Bitcoin system only provides eventual consistency. For everyday life, the time to confirm a Bitcoin transaction is prohibitively slow. In this paper we propose a new system, built on the Bitcoin blockchain, which enables strong consistency. Our system, PeerCensus, acts as a certification authority, manages peer identities in a peer-to-peer network, and ultimately enhances Bitcoin and similar systems with strong consistency. Our extensive analysis shows that PeerCensus is in a secure state...
Strong gravity and supersymmetry
International Nuclear Information System (INIS)
Chamseddine, Ali H.; Salam, A.; Strathdee, J.
1977-11-01
A supersymmetric theory is constructed for a strong f plus a weak g graviton, together with their accompanying massive gravitinos, by gaugin the gradel 0Sp(2,2,1)x 0Sp(2,2,1) structure. The mixing term between f and g fields, which makes the strong graviton massive, can be introduced through a spontaneous symmetry-breaking mechanism implemented in this note by constructing a non-linear realization of the symmetry group
International Nuclear Information System (INIS)
Ohta, Ayumi; Kobayashi, Osamu; Danielache, Sebastian O.; Nanbu, Shinkoh
2015-01-01
Highlights: • The photoisomerization between cyclohexadiene and hexatriene was simulated. • Nonadiabatic ab initio MD simulations were employed to elucidate the mechanism. • Each excitations to S_1 and S_2 were simulated using full-dimensional model. • Specific molecular motions at CoIns and molecular vibrations on S_1 PES were found. • The one-sided product branching ratio was obtained at the photoexcitation to S_2. - Abstract: The photoisomerization process between 1,3-cyclohexadiene (CHD) and 1,3,5-cis-hexatriene (HT) has been studied by nonadiabatic ab initio molecular dynamics based on trajectory surface-hopping approach with a full-dimensional reaction model. The quantum chemical calculations were treated at MS-MR-CASPT2 level for 8 electrons in 8 orbitals with the cc-pVDZ basis set. The Zhu–Nakamura formula was employed to evaluate nonadiabatic transition probabilities. S_1 and S_2 states were included in the photoisomerization dynamics. Lifetimes and CHD:HT branching ratios were computationally estimated on the basis of statistical analysis of multiple executed trajectories. The analysis of trajectories suggested that the nonadiabatic transitions at the S_0/S_1 and S_1/S_2 conical intersections (CoIn) are correlated to the Kekulé-type vibration and the C3–C4–C5 bending motion, respectively. The one-sided branching ratio was obtained by excitations to the S_2 state; 70:30. The critical branching process was found to be dominated by the location of CoIn in potential energy hypersurface of the excited state.
Mizuno, Yuta; Arasaki, Yasuki; Takatsuka, Kazuo
2016-11-14
We propose a theoretical principle to directly monitor the bifurcation of quantum wavepackets passing through nonadiabatic regions of a molecule that is placed in intense continuous wave (CW) laser fields. This idea makes use of the phenomenon of laser-driven photon emission from molecules that can undergo nonadiabatic transitions between ionic and covalent potential energy surfaces like Li + F - and LiF. The resultant photon emission spectra are of anomalous yet characteristic frequency and intensity, if pumped to an energy level in which the nonadiabatic region is accessible and placed in a CW laser field. The proposed method is designed to take the time-frequency spectrogram with an appropriate time-window from this photon emission to detect the time evolution of the frequency and intensity, which depends on the dynamics and location of the relevant nuclear wavepackets. This method is specifically designed for the study of dynamics in intense CW laser fields and is rather limited in scope than other techniques for femtosecond chemical dynamics in vacuum. The following characteristic features of dynamics can be mapped onto the spectrogram: (1) the period of driven vibrational motion (temporally confined vibrational states in otherwise dissociative channels, the period and other states of which dramatically vary depending on the CW driving lasers applied), (2) the existence of multiple nuclear wavepackets running individually on the field-dressed potential energy surfaces, (3) the time scale of coherent interaction between the nuclear wavepackets running on ionic and covalent electronic states after their branching (the so-called coherence time in the terminology of the theory of nonadiabatic interaction), and so on.
Muskatel, B H; Remacle, F; Thiemens, Mark H; Levine, R D
2011-04-12
Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N(2). The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect.
International Nuclear Information System (INIS)
Öztürk, Hakan
2014-01-01
Highlights: • The criticality problem for one-speed neutrons in homogeneous slab is investigated. • A combination of forward–backward and linear anisotropy is used. • The effect of the strongly anisotropic scattering on the critical size is analyzed. - Abstract: The criticality problem for one-speed neutrons in a uniform finite slab is studied in the case of a combination of forward and backward scattering with linearly anisotropic scattering using U N method based on the Chebyshev polynomials of second kind. The effect of the linear anisotropy on the critical thickness of the slab is investigated. The critical slab thicknesses are calculated by using Marshak boundary condition for various values of the anisotropy parameters and they are presented in the tables. In comparison to the results obtained by other methods, the results of this study are in compatible with the former ones
Ma, Jing; Fu, Yu-Long; Yu, Si-Yuan; Xie, Xiao-Long; Tan, Li-Ying
2018-03-01
A new expression of the scintillation index (SI) for a Gaussian-beam wave propagating through moderate-to-strong non-Kolmogorov turbulence is derived, using a generalized effective atmospheric spectrum and the extended Rytov approximation theory. Finite inner and outer scale parameters and high wave number “bump” are considered in the spectrum with a generalized spectral power law in the range of 3–4, instead of the fixed classical Kolmogorov power law of 11/3. The obtained SI expression is then used to analyze the effects of the spectral power law and the inner scale and outer scale on SI under various non-Kolmogorov fluctuation conditions. These results will be useful in future investigations of optical wave propagation through atmospheric turbulence.
Ghosh, Arnab; Koestner, Wolfgang; Hapke, Martin; Schlaphoff, Verena; Länger, Florian; Baumann, Rolf; Koenecke, Christian; Cornberg, Markus; Welte, Karl; Blazar, Bruce R; Sauer, Martin G
2009-04-30
Antigen-presenting cells (APCs) of host origin drive graft-versus-leukemia (GVL) effects but can also trigger life-threatening graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT) across major histocompatibility complex (MHC) barriers. We show that in vitro priming of donor lymphocytes can circumvent the need of recipient-derived APCs in vivo for mediating robust GVL effects and significantly diminishes the risk of severe GVHD. In vitro, generated and expanded T cells (ETCs) mediate anti-leukemia effects only when primed on recipient-derived APCs. Loading of APCs in vitro with leukemia cell lysate, chimerism status of the recipient, and timing of adoptive transfer after HCT are important factors determining the outcome. Delayed transfer of ETCs resulted in strong GVL effects in leukemia-bearing full chimera (FC) and mixed chimera (MC) recipients, which were comparable with the GVL/GVHD rates observed after the transfer of naive donor lymphocyte infusion (DLI). Upon early transfer, GVL effects were more pronounced with ETCs but at the expense of significant GVHD. The degree of GVHD was most severe in MCs after transfer of ETCs that had been in vitro primed either on nonpulsed recipient-derived APCs or with donor-derived APCs.
Bera, Anupam; Ghosh, Jayanta; Bhattacharya, Atanu
2017-07-28
Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO 2 energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory. We have found that DMNA relaxes back to the ground (S 0 ) state following electronic excitation to the S 1 excited state [which is an (n,π*) excited state] with a time constant of approximately 40 fs. This AIMS result is in very good agreement with the previous surface hopping-result and femtosecond laser spectroscopy result. DMNA does not dissociate during this fast internal conversion from the S 1 to the S 0 state. DMNA-Fe also undergoes extremely fast relaxation from the upper S 1 state to the S 0 state; however, this relaxation pathway is dissociative in nature. DMNA-Fe undergoes initial Fe-O, N-O, and N-N bond dissociations during relaxation from the upper S 1 state to the ground S 0 state through the respective conical intersection. The AIMS simulation reveals the branching ratio of these three channels as N-N:Fe-O:N-O = 6:3:1 (based on 100 independent simulations). Furthermore, the AIMS simulation reveals that the Fe-O bond dissociation channel exhibits the fastest (time constant 24 fs) relaxation, while the N-N bond dissociation pathway features the slowest (time constant 128 fs) relaxation. An intermediate time constant (30 fs) is found for the N-O bond dissociation channel. This is the first nonadiabatic chemical dynamics study of metal-contained energetic molecules through conical intersections.
Bera, Anupam; Ghosh, Jayanta; Bhattacharya, Atanu
2017-07-01
Conical intersections are now firmly established to be the key features in the excited electronic state processes of polyatomic energetic molecules. In the present work, we have explored conical intersection-mediated nonadiabatic chemical dynamics of a simple analogue nitramine molecule, dimethylnitramine (DMNA, containing one N-NO2 energetic group), and its complex with an iron atom (DMNA-Fe). For this task, we have used the ab initio multiple spawning (AIMS) dynamics simulation at the state averaged-complete active space self-consistent field(8,5)/6-31G(d) level of theory. We have found that DMNA relaxes back to the ground (S0) state following electronic excitation to the S1 excited state [which is an (n,π*) excited state] with a time constant of approximately 40 fs. This AIMS result is in very good agreement with the previous surface hopping-result and femtosecond laser spectroscopy result. DMNA does not dissociate during this fast internal conversion from the S1 to the S0 state. DMNA-Fe also undergoes extremely fast relaxation from the upper S1 state to the S0 state; however, this relaxation pathway is dissociative in nature. DMNA-Fe undergoes initial Fe-O, N-O, and N-N bond dissociations during relaxation from the upper S1 state to the ground S0 state through the respective conical intersection. The AIMS simulation reveals the branching ratio of these three channels as N-N:Fe-O:N-O = 6:3:1 (based on 100 independent simulations). Furthermore, the AIMS simulation reveals that the Fe-O bond dissociation channel exhibits the fastest (time constant 24 fs) relaxation, while the N-N bond dissociation pathway features the slowest (time constant 128 fs) relaxation. An intermediate time constant (30 fs) is found for the N-O bond dissociation channel. This is the first nonadiabatic chemical dynamics study of metal-contained energetic molecules through conical intersections.
Energy Technology Data Exchange (ETDEWEB)
Moritz, B; Johnston, S; Greven, M; Shen, Z-X; Devereaux, T P [Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory and Stanford University, Stanford, CA 94305 (United States); Schmitt, F; Meevasana, W; Motoyama, E M [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Lu, D H [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Kim, C [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Scalettar, R T [Physics Department, University of California-Davis, Davis, CA 95616 (United States)], E-mail: moritzb@slac.stanford.edu
2009-09-15
Recently, angle-resolved photoemission spectroscopy (ARPES) has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). This paper demonstrates, using a combination of new ARPES measurements and quantum Monte Carlo simulations, that the HEA is not simply the by-product of matrix element effects, but rather represents a cross-over from a quasi-particle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character, in both hole- and electron-doped cuprates. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. the 'waterfall'-like behavior, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying both hole and electron doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram.
Strong magnetorefractive effect in epitaxial La{sub 2/3}Ca{sub 1/3}MnO{sub 3} thin films
Energy Technology Data Exchange (ETDEWEB)
Hrabovsky, D. [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC Campus de la UAB, Bellaterra 08193, Catalonia (Spain); Herranz, G., E-mail: gherranz@icmab.e [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC Campus de la UAB, Bellaterra 08193, Catalonia (Spain); Caicedo, J.M.; Infante, I.C.; Sanchez, F.; Fontcuberta, J. [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC Campus de la UAB, Bellaterra 08193, Catalonia (Spain)
2010-05-15
We report here on the magneto-optical characterization of epitaxial La{sub 2/3}Ca{sub 1/3}MnO{sub 3} thin films. We observe that the magnetic field dependence of the magneto-optical signal measured in transverse Kerr geometry can be decomposed into even and odd contributions which evolve differently with the temperature. We demonstrate that whereas the odd component is proportional to the magnetization, the even contribution is related to the magnetorefractive effect, which is caused by the changes of the refractive index and optical conductivity with the magnetic field. This phenomenon, previously reported only at infrared wavelengths in some spin valves and granular systems, is shown here to be very relevant at visible frequencies for the colossal magnetoresistance manganites, thus allowing simultaneous optical characterization of the magnetic and magnetotransport properties. We argue that these characteristics result from inherent transport properties of these strongly correlated ferromagnetic oxides.
International Nuclear Information System (INIS)
Krajnik, N.N.; Trepakov, V.A.; Kamzina, L.S.; Sakharov, D.G.; Volik, B.A.; Pis'mennyj, V.A.; Skornyakova, K.P.
1975-01-01
An investigation was made of the transverse electrooptic effect in PbMgsub(1/3)Nbsub(2/3)O 3 subjected to alternating fields of 0-20 kV/cm intensity and 2.10-10 4 Hz frequency in the region of the broad ferroelectric phase tansition. The quadratic electrooptic coefficients (R 11 -R 12 ) exhibited relaxation-type maxima in the temperature dependences, whereas no such maxima were observed for the linear coefficients (r 33 -r 13 ) in the investigated temperature range: The latter coefficients rose monotonically when the temperature was lowered. It was concluded that the predominant despersion mechanism in strong fields was the inertia of the growth of ferroelectric domains and nuclei. The coefficients (M 11 -M 12 ), which were quadratic in respect of the polarization, increased with rising temperature and this was explained qualitatively by allowing for the contribution of orientation processes to the overall electric polarization and birefrigence. (author)
Strongly interacting Fermi gases
Directory of Open Access Journals (Sweden)
Bakr W.
2013-08-01
Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.
International Nuclear Information System (INIS)
Marier, D.
1992-01-01
This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders
Strong interactions at high energy
International Nuclear Information System (INIS)
Anselmino, M.
1995-01-01
Spin effects in strong interaction high energy processes are subtle phenomena which involve both short and long distance physics and test perturbative and non perturbative aspects of QCD. Moreover, depending on quantities like interferences between different amplitudes and relative phases, spin observables always test a theory at a fundamental quantum mechanical level; it is then no surprise that spin data are often difficult to accommodate within the existing models. A report is made on the main issues and contributions discussed in the parallel Session on the open-quote open-quote Strong interactions at high energy close-quote close-quote in this Conference. copyright 1995 American Institute of Physics
Cassidy, Tali; Bowman, Brett; McGrath, Chloe; Matzopoulos, Richard
2016-10-01
We present a brief report on a systematic review which identified, assessed and synthesized the existing evidence of the effectiveness of media campaigns in reducing youth violence. Search strategies made use of terms for youth, violence and a range of terms relating to the intervention. An array of academic databases and websites were searched. Although media campaigns to reduce violence are widespread, only six studies met the inclusion criteria. There is little strong evidence to support a direct link between media campaigns and a reduction in youth violence. Several studies measure proxies for violence such as empathy or opinions related to violence, but the link between these measures and violence perpetration is unclear. Nonetheless, some evidence suggests that a targeted and context-specific campaign, especially when combined with other measures, can reduce violence. However, such campaigns are less cost-effective to replicate over large populations than generalised campaigns. It is unclear whether the paucity of evidence represents a null effect or methodological challenges with evaluating media campaigns. Future studies need to be carefully planned to accommodate for methodological difficulties as well as to identify the specific elements of campaigns that work, especially in lower and middle income countries. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.
Strong Electroweak Symmetry Breaking
Grinstein, Benjamin
2011-01-01
Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...
Plasmons in strong superconductors
International Nuclear Information System (INIS)
Baldo, M.; Ducoin, C.
2011-01-01
We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.
Pandian, Arun; Stellingwerf, Robert F.; Abarzhi, Snezhana I.
2017-07-01
While it is a common wisdom that initial conditions influence the evolution of the Richtmyer-Meshkov instability (RMI), the research in this area is focused primarily on the effects of the wavelength and amplitude of the interface perturbation. The information has hitherto largely ignored the influences on RMI dynamics of the relative phase of waves constituting a multiwave initial perturbation and the interference of the perturbation waves. In this work we systematically study the influence of the relative phase and the interference of waves constituting a multiwave initial perturbation on a strong-shock-driven Richtmyer-Meshkov unstable interface separating ideal fluids with contrast densities. We apply group theory analysis and smoothed particle hydrodynamics numerical simulations. For verification and validation of the simulations, qualitative and quantitative comparisons are performed with rigorous zeroth-order, linear, and nonlinear theories as well as with gas dynamics experiments achieving good agreement. For a sample case of a two-wave (two-mode) initial perturbation we select the first-wave amplitude enabling the maximum initial growth rate of the RMI and we vary the second-wave amplitude from 1% to 100% of the first-wave amplitude. We also vary the relative phase of the first and second waves and consider the in-phase, the antiphase and the random-phase cases. We find that the relative phase and the interference of waves are important factors of RMI dynamics influencing qualitatively and quantitatively the symmetry, morphology, and growth rate of the Richtmyer-Meshkov unstable interface, as well as the order and disorder in strong-shock-driven RMI.
Kaifas, Delphine; Malleret, Laure; Kumar, Naresh; Fétimi, Wafa; Claeys-Bruno, Magalie; Sergent, Michelle; Doumenq, Pierre
2014-05-15
Nanoscale zero-valent iron (nZVI) particles are efficient for the remediation of aquifers polluted by trichloroethylene (TCE). But for on-site applications, their reactivity can be affected by the presence of common inorganic co-pollutants, which are equally reduced by nZVI particles. The aim of this study was to assess the potential positive effects of nZVI surface modification and concentration level on TCE removal in the concomitant presence of two strong oxidants, i.e., Cr(VI) and NO3(-). A design of experiments, testing four factors (i.e. nZVI concentration, nZVI surface modification, Cr(VI) concentration and NO3(-) concentration), was used to select the best trials for the identification of the main effects of the factors and of the factors interactions. The effects of these factors were studied by measuring the following responses: TCE removal rates at different times, degradation kinetic rates, and the transformation products formed. As expected, TCE degradation was delayed or inhibited in most of the experiments, due to the presence of inorganics. The negative effects of co-pollutants can be palliated by combining surface modification with a slight increase in nZVI concentration. Encouragingly, complete TCE removal was achieved for some given experimental conditions. Noteworthily, nZVI surface modification was found to promote the efficient degradation of TCE. When degradation occurred, TCE was mainly transformed into innocuous non-chlorinated transformation products, while hazardous chlorinated transformation products accounted for a small percentage of the mass-balance. Copyright © 2014 Elsevier B.V. All rights reserved.
Chew, S Y; Cheah, Y K; Seow, H F; Sandai, D; Than, L T L
2015-05-01
This study investigates the antagonistic effects of the probiotic strains Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 against vulvovaginal candidiasis (VVC)-causing Candida glabrata. Growth inhibitory activities of Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains against C. glabrata were demonstrated using a spot overlay assay and a plate-based microtitre assay. In addition, these probiotic lactobacilli strains also exhibited potent candidacidal activity against C. glabrata, as demonstrated by a LIVE/DEAD yeast viability assay performed using confocal laser scanning microscopy. The metabolic activities of all C. glabrata strains were completely shut down in response to the challenges by the probiotic lactobacilli strains. In addition, both probiotic lactobacilli strains exhibited strong autoaggregation and coaggregation phenotypes in the presence of C. glabrata, which indicate that these lactobacilli strains may exert their probiotic effects through the formation of aggregates and, thus the consequent prevention of colonization by C. glabrata. Probiotic Lact. rhamnosus GR-1 and Lact. reuteri RC-14 strains exhibited potent antagonistic activities against all of the tested C. glabrata strains. These lactobacilli exhibited antifungal effects, including those attributed to their aggregation abilities, and their presence caused the cessation of growth and eventual cell death of C. glabrata. This is the first study to report on the antagonistic effects of these probiotic lactobacilli strains against the non-Candida albicans Candida (NCAC) species C. glabrata. © 2015 The Authors published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.
Cardazone, Gina; U Sy, Angela; Chik, Ivan; Corlew, Laura Kate
2014-06-01
Network analysis and GIS enable the presentation of meaningful data about organizational relationships and community characteristics, respectively. Together, these tools can provide a concrete representation of the ecological context in which coalitions operate, and may help coalitions identify opportunities for growth and enhanced effectiveness. This study uses network analysis and GIS mapping as part of an evaluation of the One Strong 'Ohana (OSO) campaign. The OSO campaign was launched in 2012 via a partnership between the Hawai'i Children's Trust Fund (HCTF) and the Joyful Heart Foundation. The OSO campaign uses a collaborative approach aimed at increasing public awareness of child maltreatment and protective factors that can prevent maltreatment, as well as enhancing the effectiveness of the HCTF Coalition. This study focuses on three elements of the OSO campaign evaluation: (1) Network analysis exploring the relationships between 24 active Coalition member organizations, (2) GIS mapping of responses to a randomized statewide phone survey (n = 1,450) assessing awareness of factors contributing to child maltreatment, and (3) Combined GIS maps and network data, illustrating opportunities for geographically-targeted coalition building and public awareness activities.
Directory of Open Access Journals (Sweden)
Sarah Rajkumar
2017-05-01
Full Text Available American Indians experience high rates of cardiovascular diseases (CVD. Environmental tobacco smoke (ETS has been linked to CVD, possibly due to pro-inflammatory and oxidative stress pathways. We examined the relationship between self-reported exposure to ETS and fatal and nonfatal CVD incidence using Cox proportional hazards models among 1843 non-smoking American Indians participating in the Strong Heart Study. We also evaluated potential modifying effects of several dietary nutrients high in anti-inflammatory and anti-oxidant properties with ETS exposure on fatal and nonfatal CVD by creating interaction terms between ETS exposure and the dietary variable. Participants exposed to ETS had a higher hazard (hazard ratio: 1.22; 95% confidence interval, 1.03 to 1.44 for developing CVD compared to persons not exposed. Interaction analyses suggested stronger effects of ETS on CVD incidence among those consuming diets lower in vitamin E as compared to those consuming higher amounts, particularly on the additive scale. Additional research is recommended to clarify whether public health prevention strategies should simultaneously target reductions in ETS exposures and improvements in diets that may exceed the expected benefits of targeting these risk factors separately.
Aerts, R.; Callaghan, T.V.; Dorrepaal, E.; van Logtestijn, R.S.P; Cornelissen, J.H.C.
2012-01-01
Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on
International Nuclear Information System (INIS)
Gorenstein, M. I.; Gazdzicki, M.
2011-01-01
Analysis of fluctuations of hadron production properties in collisions of relativistic particles profits from use of measurable intensive quantities which are independent of system size variations. The first family of such quantities was proposed in 1992; another is introduced in this paper. Furthermore we present a proof of independence of volume fluctuations for quantities from both families within the framework of the grand canonical ensemble. These quantities are referred to as strongly intensive ones. Influence of conservation laws and resonance decays is also discussed.
Rajbhandari-Thapa, Janani; Bennett, Ashley; Keong, Farrah; Palmer, Wendy; Hardy, Trisha; Welsh, Jean
The goal of the Strong4Life School Nutrition Program is to promote healthy eating in school cafeterias in Georgia by training school nutrition managers and staff members to implement changes in the cafeteria to nudge children to make healthier choices. The objective of our study was to evaluate program effect on (1) school nutrition manager and staff member knowledge of evidence-based strategies and their self-efficacy to make positive changes, (2) the school cafeteria environment, and (3) National School Lunch Program participation. We assessed changes in participant knowledge, beliefs, and self-efficacy by administering a survey before and after training (February-July 2015); a follow-up survey (3 school months posttraining) assessed changes in the cafeteria. A total of 842 school nutrition managers and staff members were trained and completed pre- and posttraining surveys; 325 managers completed the follow-up survey. We used cafeteria records from a subsample of the first schools trained (40 intervention and 40 control) to assess National School Lunch Program participation. From pretraining to posttraining, we found a significant increase in manager and staff member (n = 842) knowledge of strategies for enhancing taste perception through the use of creative menu item names (from 78% to 95%, P managers (n = 325) reported increased use of evidence-based serving strategies: visibility (from 84% to 96% for placing healthy options in >2 locations, P managers and staff members in Smarter Lunchrooms Movement techniques may be an effective way to make changes in the school cafeteria environment to encourage healthier choices among students. Additional studies allowing time for more complex changes to be implemented are needed to assess the full effect of the program.
An undulator with non-adiabatic tapering for the IFEL project
Varfolomeev, A A; Yarovoi, T V; Musumeci, P; Pellegrini, C; Rosenzweig, J
2002-01-01
We describe the design of a planar undulator with unusually strong tapering, for the inverse FEL experiment to be carried out in Neptune Lab. (Nucl. Instr. and Meth. A 410 (1998) 437) at UCLA. A powerful TW CO sub 2 laser will be used to accelerate electrons up to 50-60 MeV in 50 cm long undulator. A strong undulator tapering is needed because of the short Rayleigh length of the laser beam. Both the magnetic field and the undulator period are tapered to provide synchronicity of the laser beam interaction with a captured electron bunch along the whole undulator length. The most critical part of the undulator is the region near the laser focus. The main characteristics of the IFEL, such as the percentage of trapped electrons, energy of accelerated electrons and sensitivity to the laser focus transverse position, are given. The general principles of the design of this undulator construction can also be useful for high efficiency FEL amplifiers of intense laser modes.
Levy, David; de Almeida, Liz Maria; Szklo, Andre
2012-01-01
Brazil has reduced its smoking rate by about 50% in the last 20 y. During that time period, strong tobacco control policies were implemented. This paper estimates the effect of these stricter policies on smoking prevalence and associated premature mortality, and the effect that additional policies may have. The model was developed using the SimSmoke tobacco control policy model. Using policy, population, and smoking data for Brazil, the model assesses the effect on premature deaths of cigarette taxes, smoke-free air laws, mass media campaigns, marketing restrictions, packaging requirements, cessation treatment programs, and youth access restrictions. We estimate the effect of past policies relative to a counterfactual of policies kept to 1989 levels, and the effect of stricter future policies. Male and female smoking prevalence in Brazil have fallen by about half since 1989, which represents a 46% (lower and upper bounds: 28%-66%) relative reduction compared to the 2010 prevalence under the counterfactual scenario of policies held to 1989 levels. Almost half of that 46% reduction is explained by price increases, 14% by smoke-free air laws, 14% by marketing restrictions, 8% by health warnings, 6% by mass media campaigns, and 10% by cessation treatment programs. As a result of the past policies, a total of almost 420,000 (260,000-715,000) deaths had been averted by 2010, increasing to almost 7 million (4.5 million-10.3 million) deaths projected by 2050. Comparing future implementation of a set of stricter policies to a scenario with 2010 policies held constant, smoking prevalence by 2050 could be reduced by another 39% (29%-54%), and 1.3 million (0.9 million-2.0 million) out of 9 million future premature deaths could be averted. Brazil provides one of the outstanding public health success stories in reducing deaths due to smoking, and serves as a model for other low and middle income nations. However, a set of stricter policies could further reduce smoking and save
Xia, Qing Qing; Zhang, Lian Ying; Zhao, Zhi Liang; Li, Chang Ming
2017-11-15
Uniform Pt 1 Ru 0.5 Sn 0.5 ternary alloy nanoparticles are in situ deposited on reduced graphene oxide (Pt 1 Ru 0.5 Sn 0.5 -RGO) through its functional groups and defects as nucleation sites to greatly electrocatalyze ethanol oxidation reaction for much higher mass current densities, larger apparent specific current densities and better stability than commercial Pt-C catalyst (Pt-C(commer)). Mechanistic studies indicate that the excellent electrocatalytic activity and anti-poisoning are resulted from a strong ligand effect of the ternary alloy components, in which the charge transfer is boosted while decreasing the density of states close to the Fermi level of Pt to reduce bond energy between Pt and CO-like adsorbates for greatly improved anti-poisoning ability. This work holds a great promise to fabricate a high performance anode catalyst with a low Pt loading for direct ethanol fuel cells. Copyright © 2017. Published by Elsevier Inc.
Directory of Open Access Journals (Sweden)
Partha Mandal
2017-12-01
Full Text Available In this work, we analyze a bi-dimensional differential equation system obtained by considering Holling type II functional response in prey–predator model with strong Allee effect in prey. One of the important consequence of this modification is the existence of separatrix curve which divides the behaviour of the trajectories in the phase plane. The results show that the origin is an attractor for any set of parameter values. Axial equilibrium points are stable or unstable according to the different parametric restrictions. The unique positive equilibrium point, if it exists, can be either an attractor or a repeller surrounded by a limit cycle, whose stability and uniqueness are also established. Therefore long-term coexistence of both populations is possible or they can go to extinction. Conditions on the parameter values are derived to show that the positive equilibrium point can be emerged or annihilated through transcritical bifurcation at axial equilibrium points. The existence of two heteroclinic curves is also established. It is also demonstrated that the origin is a global attractor in the phase plane for some parameter values, which implies that there are satisfying conditions where both populations can go to extinction. Ecological interpretations of all analytical results are provided thoroughly.
Suo, Tongchuan; Whitmore, Mark D
2014-11-28
We examine end-tethered polymers in good solvents, using one- and three-dimensional self-consistent field theory, and strong stretching theories. We also discuss different tethering scenarios, namely, mobile tethers, fixed but random ones, and fixed but ordered ones, and the effects and important limitations of including only binary interactions (excluded volume terms). We find that there is a "mushroom" regime in which the layer thickness is independent of the tethering density, σ, for systems with ordered tethers, but we argue that there is no such plateau for mobile or disordered anchors, nor is there one in the 1D theory. In the other limit of brushes, all approaches predict that the layer thickness scales linearly with N. However, the σ(1/3) scaling is a result of keeping only excluded volume interactions: when the full potential is included, the dependence is faster and more complicated than σ(1/3). In fact, there does not appear to be any regime in which the layer thickness scales in the combination Nσ(1/3). We also compare the results for two different solvents with each other, and with earlier Θ solvent results.