Effective quantum dynamics of interacting systems with inhomogeneous coupling
Lopez, C. E.; Retamal, J. C.; Christ, H.; Solano, E.
2007-03-15
We study the quantum dynamics of a single mode (particle) interacting inhomogeneously with a large number of particles and introduce an effective approach to find the accessible Hilbert space, where the dynamics takes place. Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g., N atomic qubits coupled to a single cavity mode, or to a motional mode in trapped ions) and the inhomogeneous coupling of an electron spin to N nuclear spins in a quantum dot.
Coupled effects of local movement and global interaction on contagion
NASA Astrophysics Data System (ADS)
Zhong, Li-Xin; Xu, Wen-Juan; Chen, Rong-Da; Qiu, Tian; Shi, Yong-Dong; Zhong, Chen-Yang
2015-10-01
By incorporating segregated spatial domain and individual-based linkage into the SIS (susceptible-infected-susceptible) model, we propose a generalized epidemic model which can change from the territorial epidemic model to the networked epidemic model. The role of the individual-based linkage between different spatial domains is investigated. As we adjust the timescale parameter τ from 0 to unity, which represents the degree of activation of the individual-based linkage, three regions are found. Within the region of 0 < τ < 0.02, the epidemic is determined by local movement and is sensitive to the timescale τ. Within the region of 0.02 < τ < 0.5, the epidemic is insensitive to the timescale τ. Within the region of 0.5 < τ < 1, the outbreak of the epidemic is determined by the structure of the individual-based linkage. As we keep an eye on the first region, the role of activating the individual-based linkage in the present model is similar to the role of the shortcuts in the two-dimensional small world network. Only activating a small number of the individual-based linkage can prompt the outbreak of the epidemic globally. The role of narrowing segregated spatial domain and reducing mobility in epidemic control is checked. These two measures are found to be conducive to curbing the spread of infectious disease only when the global interaction is suppressed. A log-log relation between the change in the number of infected individuals and the timescale τ is found. By calculating the epidemic threshold and the mean first encounter time, we heuristically analyze the microscopic characteristics of the propagation of the epidemic in the present model.
Baalrud, Scott D.; Daligault, Jérôme
2014-05-15
A method for extending traditional plasma transport theories into the strong coupling regime is presented. Like traditional theories, this is based on a binary scattering approximation, but where physics associated with many body correlations is included through the use of an effective interaction potential. The latter is simply related to the pair-distribution function. Modeling many body effects in this manner can extend traditional plasma theory to orders of magnitude stronger coupling. Theoretical predictions are tested against molecular dynamics simulations for electron-ion temperature relaxation as well as diffusion in one component systems. Emphasis is placed on the connection with traditional plasma theory, where it is stressed that the effective potential concept has precedence through the manner in which screening is imposed. The extension to strong coupling requires accounting for correlations in addition to screening. Limitations of this approach in the presence of strong caging are also discussed.
Behnia, Behnoush; Heinrichs, Markus; Bergmann, Wiebke; Jung, Stefanie; Germann, Janine; Schedlowski, Manfred; Hartmann, Uwe; Kruger, Tillmann H C
2014-03-01
Knowledge about the effects of the neuropeptide oxytocin (OXT) on human sexual behaviors and partner interactions remains limited. Based on our previous studies, we hypothesize that OXT should be able to positively influence parameters of sexual function and couple interactions. Employing a naturalistic setting involving 29 healthy heterosexual couples (n=58 participants), we analyzed the acute effects of intranasally administered OXT (24IU) on sexual drive, arousal, orgasm and refractory aspects of sexual behavior together with partner interactions. Data were assessed by psychometric instruments (Acute Sexual Experiences Scale, Arizona Sexual Experience Scale) as well as biomarkers, such as cortisol, α-amylase and heart rate. Intranasal OXT administration did not alter "classical" parameters of sexual function, such as sexual drive, arousal or penile erection and lubrication. However, analysis of variance and a hierarchical linear model (HLM) revealed specific effects related to the orgasmic/post-orgasmic interval as well as parameters of partner interactions. According to HLM analysis, OXT increased the intensity of orgasm, contentment after sexual intercourse and the effect of study participation. According to ANOVA analysis, these effects were more pronounced in men. Men additionally indicated higher levels of sexual satiety after sexual intercourse with OXT administration. Women felt more relaxed and subgroups indicated better abilities to share sexual desires or to empathize with their partners. The effect sizes were small to moderate. Biomarkers indicated moderate psychophysiological activation but were not affected by OXT, gender or method of contraception. Using a naturalistic setting, intranasal OXT administration in couples exerted differential effects on parameters of sexual function and partner interactions. These results warrant further investigations, including subjects with sexual and relationship problems. PMID:24503174
Audus, Debra J; Starr, Francis W; Douglas, Jack F
2016-02-21
The interactions of molecules and particles in solution often involve an interplay between isotropic and highly directional interactions that lead to a mutual coupling of phase separation and self-assembly. This situation arises, for example, in proteins interacting through hydrophobic and charged patch regions on their surface and in nanoparticles with grafted polymer chains, such as DNA. As a minimal model of complex fluids exhibiting this interaction coupling, we investigate spherical particles having an isotropic interaction and a constellation of five attractive patches on the particle's surface. Monte Carlo simulations and mean-field calculations of the phase boundaries of this model depend strongly on the relative strength of the isotropic and patch potentials, where we surprisingly find that analytic mean-field predictions become increasingly accurate as the directional interactions become increasingly predominant. We quantitatively account for this effect by noting that the effective interaction range increases with increasing relative directional to isotropic interaction strength. We also identify thermodynamic transition lines associated with self-assembly, extract the entropy and energy of association, and characterize the resulting cluster properties obtained from simulations using percolation scaling theory and Flory-Stockmayer mean-field theory. We find that the fractal dimension and cluster size distribution are consistent with those of lattice animals, i.e., randomly branched polymers swollen by excluded volume interactions. We also identify a universal functional form for the average molecular weight and a nearly universal functional form for a scaling parameter characterizing the cluster size distribution. Since the formation of branched clusters at equilibrium is a common phenomenon in nature, we detail how our analysis can be used in experimental characterization of such associating fluids. PMID:26896996
NASA Astrophysics Data System (ADS)
Audus, Debra J.; Starr, Francis W.; Douglas, Jack F.
2016-02-01
The interactions of molecules and particles in solution often involve an interplay between isotropic and highly directional interactions that lead to a mutual coupling of phase separation and self-assembly. This situation arises, for example, in proteins interacting through hydrophobic and charged patch regions on their surface and in nanoparticles with grafted polymer chains, such as DNA. As a minimal model of complex fluids exhibiting this interaction coupling, we investigate spherical particles having an isotropic interaction and a constellation of five attractive patches on the particle's surface. Monte Carlo simulations and mean-field calculations of the phase boundaries of this model depend strongly on the relative strength of the isotropic and patch potentials, where we surprisingly find that analytic mean-field predictions become increasingly accurate as the directional interactions become increasingly predominant. We quantitatively account for this effect by noting that the effective interaction range increases with increasing relative directional to isotropic interaction strength. We also identify thermodynamic transition lines associated with self-assembly, extract the entropy and energy of association, and characterize the resulting cluster properties obtained from simulations using percolation scaling theory and Flory-Stockmayer mean-field theory. We find that the fractal dimension and cluster size distribution are consistent with those of lattice animals, i.e., randomly branched polymers swollen by excluded volume interactions. We also identify a universal functional form for the average molecular weight and a nearly universal functional form for a scaling parameter characterizing the cluster size distribution. Since the formation of branched clusters at equilibrium is a common phenomenon in nature, we detail how our analysis can be used in experimental characterization of such associating fluids.
Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf
2015-05-01
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
NASA Astrophysics Data System (ADS)
Vivoni, E. R.; Istanbulluoglu, E.; Bras, R. L.
2003-12-01
The catchment hydrologic response to rainfall and the evolution of the river basin network and landscape morphology are closely linked phenomena, albeit active over different temporal scales. While the relation between hydrograph shape and catchment form has long been hypothesized, little is yet understood about the evolution of the basin hydrologic response with catchment age or geomorphic condition. Similarly, the long-term morphologic changes and feedbacks associated with a spatially-variable, evolving runoff response are still unknown. Understanding the complex interaction between basin hydrology and geomorphology was an important pursuit during Michael J. Kirkby's scientific career. In this study, we describe the interactive effects and feedbacks between the basin hydrograph (hydrologic response) and shape (geomorphic response) utilizing two state-of-the-art models: the Channel-Hillslope Integrated Landscape Development (CHILD) and the TIN-based Real-time Integrated Basin Simulator (tRIBS). We first illustrate the changes occurring in the basin hydrograph, variable source area and channel network as the catchment evolves. We then describe how the spatially-explicit hydrologic response from various mechanisms and its associated moisture field directly impacts the erosion and subsequently the basin shape. Quantitative comparisons are then made between a set of interactive and non-interactive simulations for idealized conditions. Our ultimate goal is to highlight the need for coupling distributed simulations of catchment hydrology and geomorphology for investigating the interaction between basin and hydrograph shape.
The Effects of Three Methods of Observation on Couples in Interactional Research.
ERIC Educational Resources Information Center
Carpenter, Linda J.; Merkel, William T.
1988-01-01
Assessed the effects of three different methods of observation of couples (one-way mirror, audio recording, and video recording) on 30 volunteer, nonclinical married couples. Results suggest that types of observation do not produce significantly different effects on nonclinical couples. (Author/ABL)
NASA Astrophysics Data System (ADS)
Rajput, Gagan; Chand, S.; Ahluwalia, P. K.; Sharma, K. C.
2010-10-01
In this paper, we present a theoretical study of correlated electronic transport through coupled double quantum dot (DQD) system attached to normal leads, using a generalised two impurity Anderson Hamiltonian in the presence of intra- and inter-dot Coulomb interactions. A generic formulation from which different structures, i.e. series, symmetric as well as asymmetric parallel and T-shape, can be obtained easily, is developed using Keldysh non-equilibrium Green functions method. The occupation numbers and correlators appearing in the formulation have been calculated in a self-consistent manner. A special attention is paid to investigate the ZBM in the differential conductance, which appears, develops and disappears over a particular range of interdot Coulomb interaction, in the configuration of interest. The ZBM is found to result from the renormalization of energy levels induced by the interdot Coulomb interaction and therefore an attempt has been made to understand it within the framework of local density of states. The interdot tunneling is found to enhance the effect of the interdot Coulomb interaction in inducing the ZBM in all the three configurations. Calculations for the T-shape configuration reveal that non-zero value of the interdot tunneling is an essential condition for the appearance of the ZBM in the differential conductance.
Interaction effects on the tunneling of electron-hole pairs in coupled quantum dots
NASA Astrophysics Data System (ADS)
Guerrero, Hector M.; Cocoletzi, Gregorio H.; Ulloa, Sergio E.
2001-03-01
The transit time of carriers is beginning to be an important parameter in the physical operation of semiconductor quantum dot `devices'. In the present work, we study the coherent propagation of electron-hole pairs in coupled self-assembled quantum dots in close proximity. These systems, achieved experimentally in a number of different geometries, have been recently implemented as a novel storage of optical information that may give rise to smart pixel technology in the near future [1]. Here, we apply an effective mass hamiltonian approach and solve numerically the time dependent Schroedinger equation of a system of photo-created electron-hole pairs in the dots. Our approach takes into account both Coulomb interactions and confinement effects. The time evolution is investigated in terms of the structural parameters for typical InAs-GaAs dots. Different initial conditions are considered, reflecting the basic processes that would take place in these experiments. We study the probabilities of finding the electron and hole in either the same or adjacent quantum dot, and study carefully the role of interactions in this behavior. [1] T. Lundstrom, W. Schoenfeld, H. Lee, and P. M. Petroff, Science 286, 2312 (1999).
NASA Astrophysics Data System (ADS)
Jiang, Li; Zhang, Guo-Feng
2016-08-01
The effects of nuclear field and spin-orbit interaction on dense coding and swap operation are studied in detail for both the antiferromagnetic (AFM) and ferromagnetic (FM) coupling cases. The conditions for a valid dense coding and under which swap operation is feasible are given.
Fluctuation-induced transport of two coupled particles: Effect of the interparticle interaction
NASA Astrophysics Data System (ADS)
Makhnovskii, Yurii A.; Rozenbaum, Viktor M.; Sheu, Sheh-Yi; Yang, Dah-Yen; Trakhtenberg, Leonid I.; Lin, Sheng Hsien
2014-06-01
We consider a system of two coupled particles fluctuating between two states, with different interparticle interaction potentials and particle friction coefficients. An external action drives the interstate transitions that induces reciprocating motion along the internal coordinate x (the interparticle distance). The system moves unidirectionally due to rectification of the internal motion by asymmetric friction fluctuations and thus operates as a dimeric motor that converts input energy into net movement. We focus on how the law of interaction between the particles affects the dimer transport and, in particular, the role of thermal noise in the motion inducing mechanism. It is argued that if the interaction potential behaves at large distances as xα, depending on the value of the exponent α, the thermal noise plays a constructive (α > 2), neutral (α = 2), or destructive (α < 2) role. In the case of α = 1, corresponding piecewise linear potential profiles, an exact solution is obtained and discussed in detail.
Sexual Interaction in Nonclinical Couples.
ERIC Educational Resources Information Center
Woody, Jane D.; D'Souza, Henry J.
1997-01-01
Reports on the sexual functioning and interaction of 58 nonclinical heterosexual couples as measured by the Sexual Interaction System Scale (SISS). On all five SISS factors, the nonclinical sample scored significantly better than persons in therapy for sexual dysfunction; they also reported satisfactory relationship adjustment and high levels of…
NASA Astrophysics Data System (ADS)
Kolasiński, K.; Mreńca-Kolasińska, A.; Szafran, B.
2016-01-01
We analyze the effective Landé factor g* and its dependence on the orientation of the external magnetic field for a quantum point contact defined in the two-dimensional electron gas. The paper simulates the experimental procedure for evaluation of the effective Landé factors from the transconductance of a biased device in an external magnetic field. The contributions of the orbital effects of the magnetic field, the electron-electron interaction, and spin-orbit (SO) coupling are studied in low-temperature conditions (0.5 K). The anisotropy of the g* factors for the in-plane magnetic field orientation, which seems counterintuitive from the perspective of the effective SO magnetic field, is explained in an analytical model of the constriction as due to the SO-induced subband mixing. The asymmetry of the transconductance as a function of the gate voltage is obtained in agreement with the experimental data and the results are explained as due to depletion of the electron gas within the quantum point contact constriction and the related reduction of the screening as described within the DFT approach. The results for transconductance and the g* factors obtained are in a good agreement with the experimental data [Martin et al., Phys. Rev. B 81, 041303 (2010), 10.1103/PhysRevB.81.041303].
Bessette, Gregory Carl
2004-09-01
Modeling the response of buried reinforced concrete structures subjected to close-in detonations of conventional high explosives poses a challenge for a number of reasons. Foremost, there is the potential for coupled interaction between the blast and structure. Coupling enters the problem whenever the structure deformation affects the stress state in the neighboring soil, which in turn, affects the loading on the structure. Additional challenges for numerical modeling include handling disparate degrees of material deformation encountered in the structure and surrounding soil, modeling the structure details (e.g., modeling the concrete with embedded reinforcement, jointed connections, etc.), providing adequate mesh resolution, and characterizing the soil response under blast loading. There are numerous numerical approaches for modeling this class of problem (e.g., coupled finite element/smooth particle hydrodynamics, arbitrary Lagrange-Eulerian methods, etc.). The focus of this work will be the use of a coupled Euler-Lagrange (CEL) solution approach. In particular, the development and application of a CEL capability within the Zapotec code is described. Zapotec links two production codes, CTH and Pronto3D. CTH, an Eulerian shock physics code, performs the Eulerian portion of the calculation, while Pronto3D, an explicit finite element code, performs the Lagrangian portion. The two codes are run concurrently with the appropriate portions of a problem solved on their respective computational domains. Zapotec handles the coupling between the two domains. The application of the CEL methodology within Zapotec for modeling coupled blast/structure interaction will be investigated by a series of benchmark calculations. These benchmarks rely on data from the Conventional Weapons Effects Backfill (CONWEB) test series. In these tests, a 15.4-lb pipe-encased C-4 charge was detonated in soil at a 5-foot standoff from a buried test structure. The test structure was composed of a
LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects
NASA Astrophysics Data System (ADS)
Riefer, A.; Friedrich, M.; Sanna, S.; Gerstmann, U.; Schindlmayr, Arno; Schmidt, W. G.
2016-02-01
The influence of electronic many-body interactions, spin-orbit coupling, and thermal lattice vibrations on the electronic structure of lithium niobate is calculated from first principles. Self-energy calculations in the G W approximation show that the inclusion of self-consistency in the Green function G and the screened Coulomb potential W opens the band gap far stronger than found in previous G0W0 calculations but slightly overestimates its actual value due to the neglect of excitonic effects in W . A realistic frozen-lattice band gap of about 5.9 eV is obtained by combining hybrid density functional theory with the QS G W0 scheme. The renormalization of the band gap due to electron-phonon coupling, derived here using molecular dynamics as well as density functional perturbation theory, reduces this value by about 0.5 eV at room temperature. Spin-orbit coupling does not noticeably modify the fundamental gap but gives rise to a Rashba-like spin texture in the conduction band.
NASA Astrophysics Data System (ADS)
Patricola, C. M.; Chang, P.; Saravanan, R.; Montuoro, R.
2012-04-01
The sensitivity of simulated strength, track, and structure of Hurricane Katrina to atmospheric model resolution, cumulus parameterization, and initialization time, as well as mesoscale ocean-atmosphere interactions with and without small-scale ocean-wave effect, are investigated with a fully coupled regional climate model. The atmosphere, ocean, and wave components are represented by the Weather Research and Forecasting Model (WRF), Regional Ocean Modeling System (ROMS), and Simulating WAves Nearshore (SWAN) model. Uncoupled atmosphere-only simulations with horizontal resolutions of 1, 3, 9, and 27 km show that while the simulated cyclone track is highly sensitive to initialization time, its dependence on model resolution is relatively weak. Using NCEP/CFSR reanalysis as initial and boundary conditions, WRF, even at low resolution, is able to track Katrina accurately for 3 days before it made landfall on August 29, 2005. Katrina's strength, however, is much more difficult to reproduce and exhibits a strong dependence on model resolution. At its lowest resolution (27 km), WRF is only capable of simulating a maximum strength of Category 2 storm. Even at 1 km resolution, the simulated Katrina only reaches Category 4 storm intensity. Further WRF experiments with and without cumulus parameterization reveal minor changes in strength. None of the WRF-only simulations capture the observed rapid intensification of Katrina to Category 5 when it passed over a warm Loop-Current eddy (LCE) in the Gulf of Mexico, suggesting that mesoscale ocean-atmosphere interactions involving LCEs may play a crucial role in Katrina's rapid intensification. Coupled atmosphere-ocean simulations are designed and carried out to investigate hurricane Katrina-LCE interactions with and without considering small-scale ocean wave processes in order to fully understand the dynamical ocean-atmosphere processes in the observed rapid cyclone intensification.
Interactions and thermoelectric effects in a parallel-coupled double quantum dot
NASA Astrophysics Data System (ADS)
Sierra, Miguel A.; Saiz-Bretín, M.; Domínguez-Adame, F.; Sánchez, David
2016-06-01
We investigate the nonequilibrium transport properties of a double quantum-dot system connected in parallel to two leads, including intradot electron-electron interaction. In the absence of interactions, the system supports a bound state in the continuum. This state is revealed as a Fano antiresonance in the transmission when the energy levels of the dots are detuned. Using the Keldysh nonequilibrium Green's-function formalism, we find that the occurrence of the Fano antiresonance survives in the presence of Coulomb repulsion. We give precise predictions for the experimental detection of bound states in the continuum. First, we calculate the differential conductance as a function of the applied voltage and the dot level detuning and find that crossing points in the diamond structure are revealed as minima due to the transmission antiresonances. Second, we determine the thermoelectric current in response to an applied temperature bias. In the linear regime, quantum interference gives rise to sharp peaks in the thermoelectric conductance. Remarkably, we find interaction-induced strong current nonlinearities for large thermal gradients that may lead to several nontrivial zeros in the thermocurrent. The latter property is especially attractive for thermoelectric applications.
Zeng, Xianzhong
2004-12-10
Many laser ablation applications such as laser drilling and micromachining generate cavity structures. The study of laser ablation inside a cavity is of both fundamental and practical significance. In this dissertation, cavities with different aspect ratios (depth/diameter) were fabricated in fused silica by laser micromachining. Pulsed laser ablation in the cavities was studied and compared with laser ablation on a flat surface. The formation of laser-induced plasmas in the cavities and the effects of the cavities on the ablation processes were investigated. The temperatures and electron number densities of the resulting laser-induced plasmas in the cavities were determined from spectroscopic measurements. Reflection and confinement effects by the cavity walls and plasma shielding were discussed to explain the increased temperature and electron number density with respect to increasing cavity aspect ratio. The temporal variations of the plasma temperature and electron number density inside the cavity decreased more rapidly than outside the cavity. The effect of laser energy on formation of a plasma inside a cavity was also investigated. Propagation of the shock wave generated during pulsed laser ablation in cavities was measured using laser shadowgraph imaging and compared with laser ablation on a flat surface. It is found that outside the cavity, after about 30 ns the radius of the expanding shock wave was proportional to t2/5, which corresponds to a spherical blast wave. The calculated pressures and temperatures of the shocked air outside of the cavities were higher than those obtained on the flat surface. Lasers with femtosecond pulse duration are receiving much attention for direct fabrication of microstructures due to their capabilities of high-precision ablation with minimal damage to the sample. We have also performed experimental studies of pulsed femtosecond laser ablation on the flat surface of silicon samples and compared results with pulsed nanosecond
NASA Technical Reports Server (NTRS)
Taylor, Peter R.; Lee, Timothy J.; Rendell, Alistair P.
1990-01-01
The recently proposed quadratic configuration interaction (QCI) method is compared with the more rigorous coupled cluster (CC) approach for a variety of chemical systems. Some of these systems are well represented by a single-determinant reference function and others are not. The finite order singles and doubles correlation energy, the perturbational triples correlation energy, and a recently devised diagnostic for estimating the importance of multireference effects are considered. The spectroscopic constants of CuH, the equilibrium structure of cis-(NO)2 and the binding energies of Be3, Be4, Mg3, and Mg4 were calculated using both approaches. The diagnostic for estimating multireference character clearly demonstrates that the QCI method becomes less satisfactory than the CC approach as non-dynamical correlation becomes more important, in agreement with a perturbational analysis of the two methods and the numerical estimates of the triple excitation energies they yield. The results for CuH show that the differences between the two methods become more apparent as the chemical systems under investigation becomes more multireference in nature and the QCI results consequently become less reliable. Nonetheless, when the system of interest is dominated by a single reference determinant both QCI and CC give very similar results.
Krishtopenko, S. S.
2015-02-15
The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system.
Interaction function of oscillating coupled neurons
Dodla, Ramana; Wilson, Charles J.
2013-01-01
Large scale simulations of electrically coupled neuronal oscillators often employ the phase coupled oscillator paradigm to understand and predict network behavior. We study the nature of the interaction between such coupled oscillators using weakly coupled oscillator theory. By employing piecewise linear approximations for phase response curves and voltage time courses, and parameterizing their shapes, we compute the interaction function for all such possible shapes and express it in terms of discrete Fourier modes. We find that reasonably good approximation is achieved with four Fourier modes that comprise of both sine and cosine terms. PMID:24229210
Magnetostatic interactions in antiferromagnetically coupled patterned media.
Deng, S; Aung, K O; Piramanayagam, S N; Sbiaa, R
2011-03-01
In an array of closely spaced magnetic islands as in patterned media, magnetostatic interactions play a major role in widening the switching field distribution and reducing the thermal stability. Patterned antiferromagnetically coupled (AFC) media provide interesting systems for studying the effect of magnetostatic interactions on the reversal of closely spaced AFC bits in an array, as AFC structure helps to reduce the remanent magnetization (M(r)), leading to reduced magnetostatic interactions. Here, we study the magnetic reversal of single domain-patterned AFC CoCrPt:oxide bilayer system with perpendicular magnetic anisotropy, by imaging the remanence state of the bits after the application of a magnetic field with magnetic force microscopy (MFM). The influence of magnetostatic fields from the neighboring bits on the switching field distribution (SFD) for an entity in a patterned media is studied by varying the stabilizing layer thickness of the AFC structure and bit spacing. We observe a distinct increase in stability and coercivity with an increase in stabilizing layer thickness for the 40 nm spaced bits. This demonstrates the effectiveness of the AFC structure for reducing magnetostatic interactions in patterned media, such that high thermal stability can be achieved by the reduced M(r), without writability issues. PMID:21449425
NASA Astrophysics Data System (ADS)
Farago, J.; Meyer, H.; Baschnagel, J.; Semenov, A. N.
2012-05-01
A mode-coupling theory (MCT) version (called hMCT thereafter) of a recently presented theory [Farago, Meyer, and Semenov, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.178301 107, 178301 (2011)] is developed to describe the diffusional properties of a tagged polymer in a melt. The hMCT accounts for the effect of viscoelastic hydrodynamic interactions (VHIs), that is, a physical mechanism distinct from the density-based MCT (dMCT) described in the first paper of this series. The two versions of the MCT yield two different contributions to the asymptotic behavior of the center-of-mass velocity autocorrelation function (c.m. VAF). We show that in most cases the VHI mechanism is dominant; for long chains and prediffusive times it yields a negative tail ∝-N-1/2t-3/2 for the c.m. VAF. The case of non-momentum-conserving dynamics (Langevin or Monte Carlo) is discussed as well. It generally displays a distinctive behavior with two successive relaxation stages: first -N-1t-5/4 (as in the dMCT approach), then -N-1/2t-3/2. Both the amplitude and the duration of the first t-5/4 stage crucially depend on the Langevin friction parameter γ. All results are also relevant for the early time regime of entangled melts. These slow relaxations of the c.m. VAF, thus account for the anomalous subdiffusive regime of the c.m. mean square displacement widely observed in numerical and experimental works.
Periat, Aurélie; Kohler, Isabelle; Thomas, Aurélien; Nicoli, Raul; Boccard, Julien; Veuthey, Jean-Luc; Schappler, Julie; Guillarme, Davy
2016-03-25
Reversed phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) is the gold standard technique in bioanalysis. However, hydrophilic interaction chromatography (HILIC) could represent a viable alternative to RPLC for the analysis of polar and/or ionizable compounds, as it often provides higher MS sensitivity and alternative selectivity. Nevertheless, this technique can be also prone to matrix effects (ME). ME are one of the major issues in quantitative LC-MS bioanalysis. To ensure acceptable method performance (i.e., trueness and precision), a careful evaluation and minimization of ME is required. In the present study, the incidence of ME in HILIC-MS/MS and RPLC-MS/MS was compared for plasma and urine samples using two representative sets of 38 pharmaceutical compounds and 40 doping agents, respectively. The optimal generic chromatographic conditions in terms of selectivity with respect to interfering compounds were established in both chromatographic modes by testing three different stationary phases in each mode with different mobile phase pH. A second step involved the assessment of ME in RPLC and HILIC under the best generic conditions, using the post-extraction addition method. Biological samples were prepared using two different sample pre-treatments, i.e., a non-selective sample clean-up procedure (protein precipitation and simple dilution for plasma and urine samples, respectively) and a selective sample preparation, i.e., solid phase extraction for both matrices. The non-selective pretreatments led to significantly less ME in RPLC vs. HILIC conditions regardless of the matrix. On the contrary, HILIC appeared as a valuable alternative to RPLC for plasma and urine samples treated by a selective sample preparation. Indeed, in the case of selective sample preparation, the compounds influenced by ME were different in HILIC and RPLC, and lower and similar ME occurrence was generally observed in RPLC vs. HILIC for urine and plasma samples
NASA Astrophysics Data System (ADS)
Shahmansouri, M.; Mamun, A. A.
2015-07-01
The effects of strong electrostatic interaction among highly charged dust on multi-dimensional instability of dust-acoustic (DA) solitary waves in a magnetized strongly coupled dusty plasma by small- k perturbation expansion method have been investigated. We found that a Zakharov-Kuznetsov equation governs the evolution of obliquely propagating small amplitude DA solitary waves in such a strongly coupled dusty plasma. The parametric regimes for which the obliquely propagating DA solitary waves become unstable are identified. The basic properties, viz., amplitude, width, instability criterion, and growth rate, of these obliquely propagating DA solitary structures are found to be significantly modified by the effects of different physical strongly coupled dusty plasma parameters. The implications of our results in some space/astrophysical plasmas and some future laboratory experiments are briefly discussed.
Mvogo, Alain; Ben-Bolie, G H; Kofané, T C
2015-06-01
The dynamics of three coupled α-polypeptide chains of a collagen molecule is investigated with the influence of power-law long-range exciton-exciton interactions. The continuum limit of the discrete equations reveal that the collagen dynamics is governed by a set of three coupled nonlinear Schrödinger equations, whose dispersive coefficient depends on the LRI parameter r. We construct the analytic symmetric and asymmetric (antisymmetric) soliton solutions, which match with the structural features of collagen related with the acupuncture channels. These solutions are used as initial conditions for the numerical simulations of the discrete equations, which reveal a coherent transport of energy in the molecule for r > 3. The results also indicate that the width of the solitons is a decreasing function of r, which help to stabilize the solitons propagating in the molecule. To confirm further the efficiency of energy transport in the molecule, the modulational instability of the system is performed and the numerical simulations show that the energy can flow from one polypeptide chain to another in the form of nonlinear waves. PMID:26117109
NASA Astrophysics Data System (ADS)
Mvogo, Alain; Ben-Bolie, G. H.; Kofané, T. C.
2015-06-01
The dynamics of three coupled α-polypeptide chains of a collagen molecule is investigated with the influence of power-law long-range exciton-exciton interactions. The continuum limit of the discrete equations reveal that the collagen dynamics is governed by a set of three coupled nonlinear Schrödinger equations, whose dispersive coefficient depends on the LRI parameter r. We construct the analytic symmetric and asymmetric (antisymmetric) soliton solutions, which match with the structural features of collagen related with the acupuncture channels. These solutions are used as initial conditions for the numerical simulations of the discrete equations, which reveal a coherent transport of energy in the molecule for r > 3. The results also indicate that the width of the solitons is a decreasing function of r, which help to stabilize the solitons propagating in the molecule. To confirm further the efficiency of energy transport in the molecule, the modulational instability of the system is performed and the numerical simulations show that the energy can flow from one polypeptide chain to another in the form of nonlinear waves.
Coupling interaction of electromagnetic wave in a groove doublet configuration.
Ding, Lan; Liu, Jinsong; Wang, Dong; Wang, Kejia
2010-09-27
Based on the waveguide mode (WGM) method, coupling interaction of electromagnetic wave in a groove doublet configuration is studied. The formulation obtained by WGM method for a single groove [Prog. Electromagn. Res. 18, 1-17 (1998)] is extended to two grooves. By exploring the total scattered field of the configuration, coupling interaction ratios are defined to describe the interaction between grooves quantitatively. Since each groove in this groove doublet configuration is regarded as the basic unit, the effects of coupling interaction on the scattered fields of each groove can be investigated respectively. Numerical results show that an oscillatory behavior of coupling interaction is damped with increasing groove spacing. The incident and scattering angle dependence of coupling interaction is symmetrical when the two grooves are the same. For the case of two subwavelength grooves, the coupling interaction is not sensitive to the incident angle and scattering angle. Although the case of two grooves is discussed for simplicity, the formulation developed in this article can be generalized to arbitrary number of grooves. Moreover, our study offers a simple alternative to investigate and design metallic gratings, compact directional antennas, couplers, and other devices especially in low frequency regime such as THz and microwave domain. PMID:20941004
Strong coupling theory for interacting lattice models
NASA Astrophysics Data System (ADS)
Stanescu, Tudor D.; Kotliar, Gabriel
2004-11-01
We develop a strong coupling approach for a general lattice problem. We argue that this strong coupling perspective represents the natural framework for a generalization of the dynamical mean field theory (DMFT). The main result of this analysis is twofold: (1) It provides the tools for a unified treatment of any nonlocal contribution to the Hamiltonian. Within our scheme, nonlocal terms such as hopping terms, spin-spin interactions, or nonlocal Coulomb interactions are treated on equal footing. (2) By performing a detailed strong-coupling analysis of a generalized lattice problem, we establish the basis for possible clean and systematic extensions beyond DMFT. To this end, we study the problem using three different perspectives. First, we develop a generalized expansion around the atomic limit in terms of the coupling constants for the nonlocal contributions to the Hamiltonian. By analyzing the diagrammatics associated with this expansion, we establish the equations for a generalized dynamical mean-field theory. Second, we formulate the theory in terms of a generalized strong coupling version of the Baym-Kadanoff functional. Third, following Pairault, Sénéchal, and Tremblay [Phys. Rev. Lett. 80, 5389 (1998)], we present our scheme in the language of a perturbation theory for canonical fermionic and bosonic fields and we establish the interpretation of various strong coupling quantities within a standard perturbative picture.
Song, Sunmi; Graham-Engeland, Jennifer E; Mogle, Jacqueline; Martire, Lynn M
2015-12-01
We examined the effect of daily negative and positive mood on the sleep quality of knee osteoarthritis (OA) patients (N = 152) and whether a partner's daily responses to a patient's pain behaviors moderated these associations. Patients and their partners completed a baseline interview and 22 daily diary assessments. After controlling for demographic characteristics, OA severity, comorbidities, medication use, relationship satisfaction, and depressed mood, multilevel modeling analyses demonstrated main effects of negative and positive mood on sleep quality indicators. Mood and partner responses interacted such that high solicitous and punishing responses strengthened the association between negative mood and worse sleep. Further, high solicitous responses increased the degree of association between low positive mood and poor sleep, and empathic responses combined with positive mood were associated with better sleep. Results demonstrate that daily negative and positive mood fluctuations can interact with partner responses to affect sleep quality among older adults with chronic pain. PMID:26143147
Effects of Spin-Orbit Coupling on the Spin-Rotation Interaction in the AsH2 Radical
NASA Astrophysics Data System (ADS)
Duxbury, Geoffrey; Alijah, Alexander
2014-06-01
The occurence of predissociation in the electronic spectrum of AsH2 is very dependent upon the magnitude of the spin-orbit coupling parameter of the central atom. Making use of Table 5.6 in "The Spectra and Dynamics of Diatomic Molecules, ELSEVIER" by H. Lefebvre-Brion and R.W. Field, it is possible to appreciate the rapid rate of increase of the spin-orbit constants associated with the heavy central atom in the di-hydrides NH2, PH2 and AsH2. The spin-orbit constants range from 42.7 cm-1 for NH2, to 191.3 cm-1 for PH2, and 1178 cm-1 for AsH2. The effects of spin-orbit coupling may be seen in a plot of the separation of the central RQ0,9 and PQ1,N sub-bands as the value of v2' increases from 0 to 5. As the value of v2' increases beyond 2 the spectrum becomes more and more fuzzy as the effects of predissociation become more obvious. This means that unlike the example of the behaviour of PH2, where the vibronic level pattern can be followed below and above the barrier to linearity, in AsH2 and AsD2 the absorption spectrum becomes completely diffuse below the barrier to linearity in the A 2A1 state. The change in the magnitude of the doublet splittings as v2' increases may be seen in the plots of the doublet splittings showing the spin-uncoupling as a result of the increase of overall rotation. In the absorption spectrum of SbH2, recorded in 1967 by T. Barrow in the Chemistry Department at Sheffield University, all the absorption features showed the effects of predissociation, consistent with a spin-orbit constant of 2834 cm-1 for the central atom of SbH2.
Interaction function of coupled bursting neurons
NASA Astrophysics Data System (ADS)
Xia, Shi; Jiadong, Zhang
2016-06-01
The interaction functions of electrically coupled Hindmarsh–Rose (HR) neurons for different firing patterns are investigated in this paper. By applying the phase reduction technique, the phase response curve (PRC) of the spiking neuron and burst phase response curve (BPRC) of the bursting neuron are derived. Then the interaction function of two coupled neurons can be calculated numerically according to the PRC (or BPRC) and the voltage time course of the neurons. Results show that the BPRC is more and more complicated with the increase of the spike number within a burst, and the curve of the interaction function oscillates more and more frequently with it. However, two certain things are unchanged: ϕ = 0, which corresponds to the in-phase synchronization state, is always the stable equilibrium, while the anti-phase synchronization state with ϕ = 0.5 is an unstable equilibrium. Project supported by the National Natural Science Foundation of China (Grant Nos. 11272065 and 11472061).
NASA Astrophysics Data System (ADS)
Archer-Nicholls, Scott; Lowe, Douglas; Schultz, David M.; McFiggans, Gordon
2016-05-01
The Weather Research and Forecasting model with Chemistry (WRF-Chem) has been used to simulate a region of Brazil heavily influenced by biomass burning. Nested simulations were run at 5 and 1 km horizontal grid spacing for three case studies in September 2012. Simulations were run with and without fire emissions, convective parameterisation on the 5 km domain, and aerosol-radiation interactions in order to explore the differences attributable to the parameterisations and to better understand the aerosol direct effects and cloud responses. Direct aerosol-radiation interactions due to biomass burning aerosol resulted in a net cooling, with an average short-wave direct effect of -4.08 ± 1.53 Wm-2. However, around 21.7 Wm-2 is absorbed by aerosol in the atmospheric column, warming the atmosphere at the aerosol layer height, stabilising the column, inhibiting convection, and reducing cloud cover and precipitation. The changes to clouds due to radiatively absorbing aerosol (traditionally known as the semi-direct effects) increase the net short-wave radiation reaching the surface by reducing cloud cover, producing a secondary warming that counters the direct cooling. However, the magnitude of the semi-direct effect was found to be extremely sensitive to the model resolution and the use of convective parameterisation. Precipitation became organised in isolated convective cells when not using a convective parameterisation on the 5 km domain, reducing both total cloud cover and total precipitation. The SW semi-direct effect varied from 6.06 ± 1.46 with convective parameterisation to 3.61 ± 0.86 Wm-2 without. Convective cells within the 1 km domain are typically smaller but with greater updraft velocity than equivalent cells in the 5 km domain, reducing the proportion of the domain covered by cloud in all scenarios and producing a smaller semi-direct effect. Biomass burning (BB) aerosol particles acted as cloud condensation nuclei (CCN), increasing the droplet number
Casimir Interaction from Magnetically Coupled Eddy Currents
Intravaia, Francesco; Henkel, Carsten
2009-09-25
We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.
ANTENNA-COUPLED LIGHT-MATTER INTERACTIONS
NOVOTNY, LUKAS
2014-01-10
This project is focused on antenna-coupled photon emission from single quantum emitters. The properties of optical antennas are tailored to control different photophysical parameters, such as the excited state lifetime, the saturation intensity, and the quantum yield [3]. Using a single molecule coupled to an optical antenna whose position and properties can be controllably adjusted we established a detailed and quantitative understanding of light-matter interactions in nanoscale environments. We have studied various quantum emitters: single molecules [11], quantum dots [7], rareearth ions [2], and NV centers in diamond [19]. We have systematically studied the interaction of these emitters with optical antennas. The overall objective was to establish a high-level of control over the light-matter interaction. In order to eliminate the coupling to the environment, we have taken a step further and explored the possibility of levitating the quantum emitter in high vacuum. What started as a side-project soon became a main activity in our research program and led us to the demonstration of vacuum trapping and cooling of a nanoscale particle [14].
Interplay of Coulomb interaction and spin-orbit coupling
NASA Astrophysics Data System (ADS)
Bünemann, Jörg; Linneweber, Thorben; Löw, Ute; Anders, Frithjof B.; Gebhard, Florian
2016-07-01
We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagnetic phase we find a substantial renormalization of the spin-orbit coupling that enters the effective single-particle Hamiltonian for the quasiparticles. Only close to half band-filling and for sizable Coulomb interaction do we observe clear signatures of Hund's atomic rules for spin, orbital, and total angular momentum. For a finite local Hund's rule exchange interaction we find a ferromagnetically ordered state. The spin-orbit coupling considerably reduces the size of the ordered moment, it generates a small ordered orbital moment, and it induces a magnetic anisotropy. To investigate the magnetic anisotropy energy, we use an external magnetic field that tilts the magnetic moment away from the easy axis (1 ,1 ,1 ) .
Shahmansouri, M.; Mamun, A. A.
2014-03-15
Linear and nonlinear propagation of dust-acoustic waves in a magnetized strongly coupled dusty plasma is theoretically investigated. The normal mode analysis (reductive perturbation method) is employed to investigate the role of ambient/external magnetic field, obliqueness, and effective electrostatic dust-temperature in modifying the properties of linear (nonlinear) dust-acoustic waves propagating in such a strongly coupled dusty plasma. The effective electrostatic dust-temperature, which arises from strong electrostatic interactions among highly charged dust, is considered as a dynamical variable. The linear dispersion relation (describing the linear propagation characteristics) for the obliquely propagating dust-acoustic waves is derived and analyzed. On the other hand, the Korteweg-de Vries equation describing the nonlinear propagation of the dust-acoustic waves (particularly, propagation of dust-acoustic solitary waves) is derived and solved. It is shown that the combined effects of obliqueness, magnitude of the ambient/external magnetic field, and effective electrostatic dust-temperature significantly modify the basic properties of linear and nonlinear dust-acoustic waves. The results of this work are compared with those observed by some laboratory experiments.
Nonlinear interaction of meta-atoms through optical coupling
Slobozhanyuk, A. P.; Kapitanova, P. V.; Filonov, D. S.; Belov, P. A.; Powell, D. A.; Shadrivov, I. V.; Kivshar, Yu. S.; Lapine, M.; McPhedran, R. C.
2014-01-06
We propose and experimentally demonstrate a multi-frequency nonlinear coupling mechanism between split-ring resonators. We engineer the coupling between two microwave resonators through optical interaction, whilst suppressing the direct electromagnetic coupling. This allows for a power-dependent interaction between the otherwise independent resonators, opening interesting opportunities to address applications in signal processing, filtering, directional coupling, and electromagnetic compatibility.
Interaction Patterns of Premarital Couples: Typological Assessment Over Time.
ERIC Educational Resources Information Center
Norem, Rosalie H.; Olson, David H.
1983-01-01
Studied interaction styles of premarital couples (N=148) and developed a typology of couple interaction at two points in time before marriage. Results showed only 7 percent of the couples had the same type of interaction at the two testings, supporting the hypothesis that premarital relationships are fluid. (WAS)
Thermosphere-ionosphere coupling - An experiment in interactive modeling
NASA Technical Reports Server (NTRS)
Forbes, Jeffrey M.; Roble, Raymond G.
1990-01-01
Using the NCAR thermosphere general circulation model, a series of controlled experiments is performed to investigate the interactive coupling between ionospheric plasma densities and thermospheric neutral winds. The interaction is accomplished by parameterizing the F layer peak height, h(m)F2, in an empirical ionospheric model in terms of the meridional wind, v(south), and by forcing the h(m)F2 and the v(south) parameters to remain mutually coupled in a dynamical calculation. It was found that mutual coupling between forcing and meridional wind is weak during the daytime when the F layer exhibits a broad vertical structure. At night, when the F2 layer is more localized, the neutral dynamical structure is dependent on whether forcing is significantly above or below the altitude (about 275-300 km) at which ion drag effectively competes with viscosity in the neutral momentum balance.
Periat, Aurélie; Kohler, Isabelle; Bugey, Aurélie; Bieri, Stefan; Versace, François; Staub, Christian; Guillarme, Davy
2014-08-22
In this study, the influence of electrospray ionization (ESI) source design on the overall sensitivity achieved in hydrophilic interaction chromatography (HILIC) and reversed phase liquid chromatography (RPLC), was investigated. State-of-the-art triple quadrupole mass analyzers from AB Sciex, Agilent Technologies and Waters equipped with brand specific source geometries were tested with various mobile phase pH on 53 pharmaceutical compounds. The design of the ESI source showed to strongly influence the gain in sensitivity that can be achieved in HILIC compared to RPLC mode. The 6460 Triple Quadrupole LC/MS system from Agilent Technologies was particularly affected by mobile phase settings. Indeed, compared to RPLC conditions, 92% of the compounds had an increased signal-to-noise ratio at a flow rate of 300 μL/min in HILIC mode at pH 6, while this percentage dropped to only 7% at 1000 μL/min and pH 3. In contrast, the influence of flow rate and mobile phase pH on the gain in sensitivity between RPLC and HILIC was found very limited with the API 5000 LC/MS/MS system from AB Sciex, as only 15 to 36% of the tested compounds showed an enhanced sensitivity in HILIC mode. With the Xevo TQ-S instrument from Waters, superior sensitivity in HILIC was noticed for 85% of the compounds with optimal conditions (i.e., pH 3 and 1000 μL/min), whereas at sub-optimal conditions (i.e. pH 6 and 300 μL/min), it represented less than 50%. The gain in sensitivity observed in HILIC was found less significant with the recent LC-MS platforms used in this study than for old-generation instruments. Indeed, the improved ESI sources equipping the recent mass analyzers allow for enhanced evaporation efficiency, mainly for RPLC mobile phases containing high proportion of water and this even at high flow rates. PMID:25017394
RKKY interaction in a chirally coupled double quantum dot system
Heine, A. W.; Tutuc, D.; Haug, R. J.; Zwicknagl, G.; Schuh, D.; Wegscheider, W.
2013-12-04
The competition between the Kondo effect and the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction is investigated in a double quantum dots system, coupled via a central open conducting region. A perpendicular magnetic field induces the formation of Landau Levels which in turn give rise to the so-called Kondo chessboard pattern in the transport through the quantum dots. The two quantum dots become therefore chirally coupled via the edge channels formed in the open conducting area. In regions where both quantum dots exhibit Kondo transport the presence of the RKKY exchange interaction is probed by an analysis of the temperature dependence. The thus obtained Kondo temperature of one dot shows an abrupt increase at the onset of Kondo transport in the other, independent of the magnetic field polarity, i.e. edge state chirality in the central region.
Lebedev, V. S. Narits, A. A.
2013-10-15
Ion-pair formation processes are studied in collisions of Rydberg atoms with neutral particles possessing small electron affinities. Nonadiabatic transitions from a Rydberg covalent term to an ionic term of a quasi-molecule are considered using the modified Landau-Zener theory supplemented with calculation of survival factors of an anion decaying in the Coulomb field of a positive ion core. Using the technique of irreducible tensor operators and the momentum representation of the wavefunction of a highly excited atom, exact expressions are obtained for transition matrix elements and the ionic-covalent coupling parameter. The approach developed in the paper provides the description beyond the scope of a conventional assumption about a small variation of the wavefunction of the Rydberg atom on the range of electron coordinates determined by the characteristic radius of the wavefunction of the anion. This allows one to correctly consider long-range effects of the interaction between a weakly bound electron and the neutral core of a negative ion in processes under study. It is shown by the example of thermal collisions of Xe(nf) atoms with CH{sub 3}CN molecules that this is very important for a reliable quantitative description of anion formation with a low binding energy. The results are compared with experiments and calculations performed within the framework of a number of approximate methods.
Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T.; Tortell, Philippe D.
2015-01-01
Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963
Schuback, Nina; Schallenberg, Christina; Duckham, Carolyn; Maldonado, Maria T; Tortell, Philippe D
2015-01-01
Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETR(RCII), mol e- mol RCII(-1) s(-1)) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal--oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETR(RCII): CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements. PMID:26171963
NASA Astrophysics Data System (ADS)
Zhang, Yu-Qing; Zhu, Zhong-Hua; Peng, Zhao-Hui; Jiang, Chun-Lei; Tan, Lei
2016-07-01
We theoretically investigate the single-photon transport in a hybrid atom-optomechanical system embedded with two dipole-coupled two-level atoms, interacting with a single-mode optical waveguide. The transmission amplitudes for the single-photon propagation in such a hybrid system are obtained via a real-space approach. It is shown that the dipole-dipole interaction can significantly change the amplitudes and symmetries of the single-photon spectra. Interestingly, we find that the dipole-dipole interaction plays a similar role as does the positive atom-cavity detuning. In addition, the influence from the atomic dissipation can be weakened by increasing the dipole-dipole interaction.
Interaction of solitons with a string of coupled quantum dots
NASA Astrophysics Data System (ADS)
Kumar, Vijendra; Swami, O. P.; Taneja, S.; Nagar, A. K.
2016-05-01
In this paper, we develop a theory for discrete solitons interaction with a string of coupled quantum dots in view of the local field effects. Discrete nonlinear Schrodinger (DNLS) equations are used to describe the dynamics of the string. Numerical calculations are carried out and results are analyzed with the help of matlab software. With the help of numerical solutions we demonstrate that in the quantum dots string, Rabi oscillations (RO) are self trapped into stable bright Rabi solitons. The Rabi oscillations in different types of nanostructures have potential applications to the elements of quantum logic and quantum memory.
Wrapping interactions at strong coupling: The giant magnon
Janik, Romuald A.; Lukowski, Tomasz
2007-12-15
We derive generalized Luescher formulas for finite size corrections in a theory with a general dispersion relation. For the AdS{sub 5}xS{sup 5} superstring these formulas encode leading wrapping interaction effects. We apply the generalized {mu}-term formula to calculate finite size corrections to the dispersion relation of the giant magnon at strong coupling. The result exactly agrees with the classical string computation of Arutyunov, Frolov, and Zamaklar. The agreement involved a Borel resummation of all even loop orders of the BES/BHL dressing factor thus providing a strong consistency check for the choice of the dressing factor.
Magnetosphere-thermosphere coupling - An experiment in interactive modeling
NASA Technical Reports Server (NTRS)
Forbes, Jeffrey M.; Harel, Moshe
1989-01-01
The present use of the Rice convection model to investigate the electrodynamic coupling of the thermosphere to the inner magnetosphere encompasses the effects of EUV-driven and convection-driven neutral winds under quasi-equilibrium conditions. Convection-driven winds are included self-consistently and interactively; a steady-state wind parameterization is written analytically in terms of the electrostatic potential, which is in turn included in a closed-loop calculation for the electric potential itself. The simulations conducted show that, as the neutral system approaches a quasi-equilibrium state, the neutral winds play a much more significant role.
Exact Bremsstrahlung and effective couplings
NASA Astrophysics Data System (ADS)
Mitev, Vladimir; Pomoni, Elli
2016-06-01
We calculate supersymmetric Wilson loops on the ellipsoid for a large class of mathcal{N} = 2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the mathcal{N} = 4 SYM ones, we obtain interpolating functions f ( g 2) such that a given mathcal{N} = 2 SCFT observable is obtained by replacing in the corresponding mathcal{N} = 4 SYM result the coupling constant by f ( g 2). These "exact effective couplings" encode the finite, relative renormalization between the mathcal{N} = 2 and the mathcal{N} = 4 gluon propagator and they interpolate between the weak and the strong coupling. We discuss the range of their applicability.
Tunable indirect magnetic interaction mediated by spin-orbit coupled electrons in quantum well
NASA Astrophysics Data System (ADS)
Sun, Yi-Qian; Lyu, Pin
2015-01-01
By taking into account the quantum confinement, we calculated the Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic interaction between two magnetic impurities mediated by electrons with Rashba and Dresselhaus spin-orbit couplings in a quantum well. The RKKY magnetic interaction of the present system consists of conventional RKKY magnetic coupling, anisotropic magnetic couplings and Dzyaloshinsky-Moriya magnetic interaction. The above magnetic interactions strongly depend not only on the spin-orbit coupling strength, but also on the confined width and the absolute positions of two localized spins in the direction perpendicular to the plane of the layered structure due to the quantum size effect. It provides a potential way to control the RKKY magnetic interaction and its components in the quantum well with Rashba spin-orbit coupling by both the applied gate voltage and the nanostructure geometry.
Acoustic wave coupled magnetoelectric effect
NASA Astrophysics Data System (ADS)
Gao, J. S.; Zhang, N.
2016-07-01
Magnetoelectric (ME) coupling by acoustic waveguide was developed. Longitudinal and transversal ME effects of larger than 44 and 6 (V cm-1 Oe-1) were obtained with the waveguide-coupled ME device, respectively. Several resonant points were observed in the range of frequency lower than 47 kHz. Analysis showed that the standing waves in the waveguide were responsible for those resonances. The frequency and size dependence of the ME effects were investigated. A resonant condition about the geometrical size of the waveguide was obtained. Theory and experiments showed the resonant frequencies were closely influenced by the diameter and length of the waveguide. A series of double-peak curves of longitudinal magnetoelectric response were obtained, and their significance was discussed initially.
A Preliminary Investigation of Affective Interaction in Chronic Pain Couples
Johansen, Ayna Beate; Cano, Annmarie
2007-01-01
The objective of this preliminary study was to examine the extent to which affective marital interaction related to depressive symptoms in persons with chronic pain and their spouses and to pain severity in persons with pain. Couples from the community completed self-report surveys and engaged in a videotaped conversation on a topic of mutual disagreement that was coded for three affect types (i.e., anger/contempt, sadness, humor). Humor was positively related to marital satisfaction in both partners. Spouse anger/contempt and sadness were positively related to depressive symptoms in spouses. Several significant interaction effects between couple pain status (i.e., whether one or both partners reported pain) and affect also emerged. Specifically, sadness in the participant designated as the person with pain was associated with greater depressive symptoms and pain severity when only he or she reported pain whereas sadness was related to fewer depressive symptoms and less pain severity when both partners reported pain. The relationships between spouse anger and spouse depressive symptoms and between spouse humor and pain severity in the person with pain were also moderated by couple pain status. These exploratory findings can be interpreted in light of emotion regulation and pain empathy theories. For example, partners who have not experienced pain themselves may fail to empathize with persons in pain, thus preventing effective emotion regulation. When both spouses report chronic pain, expressions of negative affect may instead promote emotion regulation because the affect is experienced with a spouse who may be more empathetic. PMID:17521810
On the coupling between fluid flow and mesh motion in the modelling of fluid structure interaction
NASA Astrophysics Data System (ADS)
Dettmer, Wulf G.; Perić, Djordje
2008-12-01
Partitioned Newton type solution strategies for the strongly coupled system of equations arising in the computational modelling of fluid solid interaction require the evaluation of various coupling terms. An essential part of all ALE type solution strategies is the fluid mesh motion. In this paper, we investigate the effect of the terms which couple the fluid flow with the fluid mesh motion on the convergence behaviour of the overall solution procedure. We show that the computational efficiency of the simulation of many fluid solid interaction processes, including fluid flow through flexible pipes, can be increased significantly if some of these coupling terms are calculated exactly.
Magnetoelectric effects via pentalinear interactions
NASA Astrophysics Data System (ADS)
Zhao, Hong Jian; Grisolia, M. N.; Yang, Yurong; Íñiguez, Jorge; Bibes, M.; Chen, Xiang Ming; Bellaiche, L.
2015-12-01
Magnetoelectric multiferroic materials, particularly with the perovskite structure, are receiving a lot of attention because of their inherent coupling between electrical polarization and magnetic ordering. However, very few types of direct coupling between polarization and magnetization are known, and it is unclear whether they can be useful to the design of spintronic devices exploiting the control of magnetization by electric fields. For instance, the typical biquadratic coupling only allows changing the magnitude of the magnetization by an electric field, but it does not permit an electric-field-induced switching of the magnetization. Similarly, the so-called Lifshitz invariants allow an electric-field control of complicated magnetic orderings, but not of the magnetization. Here, we report on original direct couplings between polarization and magnetization in epitaxial perovskite films, via the use of first-principles methods and the development of an original Landau-type phenomenological theory. Our results feature pentalinear interactions involving the ferromagnetic and antiferromagnetic vectors as well as the polar distortions and oxygen octahedral tilting, and permit a number of striking effects. Examples include a continuous electric-field control of the magnetization magnitude and sign, and the discrete switching of the magnetization magnitude. Thus, the high-order, pentalinear couplings demonstrated in this work may open paths towards specific magnetoelectric effects, as well as spintronic and magnonic devices.
String coupling and interactions in type IIB matrix model
Kitazawa, Yoshihisa; Nagaoka, Satoshi
2009-05-15
We investigate the interactions of closed strings in a IIB matrix model. The basic interaction of the closed superstring is realized by the recombination of two intersecting strings. Such interaction is investigated in a IIB matrix model via two-dimensional noncommutative gauge theory in the IR limit. By estimating the probability of the recombination, we identify the string coupling g{sub s} in the IIB matrix model. We confirm that our identification is consistent with matrix string theory.
Controlling interactions between coupled photonic crystal cavities using photochromic tuning
NASA Astrophysics Data System (ADS)
Cai, Tao; Bose, Ranojoy; Solomon, Glenn; Waks, Edo
2013-03-01
Strongly coupled photonic crystal (PhC) resonator systems provide a promising platform for studying cavity quantum electrodynamics (QED) using semiconductor quantum dots (QDs). These device structures enable important applications such as photon blockade, quantum simulation, quantum-optical Josephson interferometer, and quantum phase transition of light. Many of these applications require the ability to accurately tune the resonant frequencies of individual cavities in the array, which provides a method to control their coupling interactions. This tuning method must be sufficiently local to address individual cavities spaced by less than 1 micron spatial separation. Here, we present a method for controlling the coupling interaction of photonic crystal cavity arrays by using a local and reversible photochromic tuning technique. By locally altering the refractive index of the photochromic material all-optically, the coupling interaction between two cavity modes could be modified over a tuning range as large as 700 GHz. By using this technique, we demonstrate the ability to couple photonic crystal cavities with a normal mode splitting of only 31.50 GHz. We further demonstrate that this tuning method can be extended to control the coupling interaction in larger cavity arrays.
Du, Mao-Hua
2015-04-02
We know that native point defects play an important role in carrier transport properties of CH3NH3PbI3. However, the nature of many important defects remains controversial due partly to the conflicting results reported by recent density functional theory (DFT) calculations. In this Letter, we show that self-interaction error and the neglect of spin–orbit coupling (SOC) in many previous DFT calculations resulted in incorrect positions of valence and conduction band edges, although their difference, which is the band gap, is in good agreement with the experimental value. Moreover, this problem has led to incorrect predictions of defect-level positions. Hybrid density functional calculations,more » which partially correct the self-interaction error and include the SOC, show that, among native point defects (including vacancies, interstitials, and antisites), only the iodine vacancy and its complexes induce deep electron and hole trapping levels inside of the band gap, acting as nonradiative recombination centers.« less
Computational and experimental techniques for coupled acoustic/structure interactions.
Sumali, Anton Hartono; Pierson, Kendall Hugh; Walsh, Timothy Francis; Dohner, Jeffrey Lynn; Reese, Garth M.; Day, David Minot
2004-01-01
This report documents the results obtained during a one-year Laboratory Directed Research and Development (LDRD) initiative aimed at investigating coupled structural acoustic interactions by means of algorithm development and experiment. Finite element acoustic formulations have been developed based on fluid velocity potential and fluid displacement. Domain decomposition and diagonal scaling preconditioners were investigated for parallel implementation. A formulation that includes fluid viscosity and that can simulate both pressure and shear waves in fluid was developed. An acoustic wave tube was built, tested, and shown to be an effective means of testing acoustic loading on simple test structures. The tube is capable of creating a semi-infinite acoustic field due to nonreflecting acoustic termination at one end. In addition, a micro-torsional disk was created and tested for the purposes of investigating acoustic shear wave damping in microstructures, and the slip boundary conditions that occur along the wet interface when the Knudsen number becomes sufficiently large.
Identification of coupling direction: Application to cardiorespiratory interaction
NASA Astrophysics Data System (ADS)
Rosenblum, Michael G.; Cimponeriu, Laura; Bezerianos, Anastasios; Patzak, Andreas; Mrowka, Ralf
2002-04-01
We consider the problem of experimental detection of directionality of weak coupling between two self-sustained oscillators from bivariate data. We further develop the method introduced by Rosenblum and Pikovsky [Phys. Rev. E 64, 045202 (2001)], suggesting an alternative approach. Next, we consider another framework for identification of directionality, based on the idea of mutual predictability. Our algorithms provide directionality index that shows whether the coupling between the oscillators is unidirectional or bidirectional, and quantifies the asymmetry of bidirectional coupling. We demonstrate the efficiency of three different algorithms in determination of directionality index from short and noisy data. These techniques are then applied to analysis of cardiorespiratory interaction in healthy infants. The results reveal that the direction of coupling between cardiovascular and respiratory systems varies with the age within the first 6 months of life. We find a tendency to change from nearly symmetric bidirectional interaction to nearly unidirectional one (from respiration to the cardiovascular system).
Kwong, Raymond W M; Niyogi, Som
2012-03-01
The present study investigated the mechanisms of intestinal cadmium (Cd) uptake and efflux, using isolated enterocytes of freshwater rainbow trout (Oncorhynchus mykiss) as the experimental model. The apical uptake of free Cd(2+) in the enterocytes was a saturable and high-affinity transport process. Both zinc (Zn(2+)) and iron (Fe(2+)) inhibited cellular Cd(2+) uptake through a competitive interaction, suggesting that Cd(2+) enters enterocytes via both Zn(2+) (e.g., ZIP8) and Fe(2+) (e.g., DMT1) transport pathways. Cellular Cd(2+) uptake increased in the presence of HCO(3)(-), which resembled the function of mammalian ZIP8. Cellular Cd(2+) uptake was unaffected by Ca(2+), indicating that Cd(2+) does not compete with Ca(2+) for apical uptake. Interestingly, Cd uptake was influenced by the presence of l-cysteine, and under the exposure condition where Cd(Cys)(+) was the predominant Cd species, cellular Cd uptake rate increased with the increased concentration of Cd(Cys)(+). The kinetic analysis indicated that the uptake of Cd(Cys)(+) occurs through a low capacity transport mechanism relative to that of free Cd(2+). In addition, Cd efflux from the enterocytes decreased in the presence of an ATPase inhibitor (orthovanadate), suggesting the existence of an ATPase-coupled extrusion process. Overall, our findings provide new mechanistic insights into the intestinal Cd transport in freshwater fish. PMID:21930242
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan
2015-07-14
Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
NASA Astrophysics Data System (ADS)
Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan
2015-07-01
Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.
Chaos in generically coupled phase oscillator networks with nonpairwise interactions
NASA Astrophysics Data System (ADS)
Bick, Christian; Ashwin, Peter; Rodrigues, Ana
2016-09-01
The Kuramoto-Sakaguchi system of coupled phase oscillators, where interaction between oscillators is determined by a single harmonic of phase differences of pairs of oscillators, has very simple emergent dynamics in the case of identical oscillators that are globally coupled: there is a variational structure that means the only attractors are full synchrony (in-phase) or splay phase (rotating wave/full asynchrony) oscillations and the bifurcation between these states is highly degenerate. Here we show that nonpairwise coupling—including three and four-way interactions of the oscillator phases—that appears generically at the next order in normal-form based calculations can give rise to complex emergent dynamics in symmetric phase oscillator networks. In particular, we show that chaos can appear in the smallest possible dimension of four coupled phase oscillators for a range of parameter values.
Quark and pion effective couplings from polarization effects
NASA Astrophysics Data System (ADS)
Braghin, Fábio L.
2016-05-01
A flavor SU(2) effective model for pions and quarks is derived by considering polarization effects departing from the usual quark-quark effective interaction induced by dressed gluon exchange, i.e. a global color model for QCD. For that, the quark field is decomposed into a component that yields light mesons and the quark-antiquark condensate, being integrated out by means of the auxiliary field method, and another component which yields constituent quarks, which is basically a background quark field. Within a long-wavelength and weak quark field expansion (or large quark effective mass expansion) of a quark determinant, the leading terms are found up to the second order in a zero-order derivative expansion, by neglecting vector mesons that are considerably heavier than the pion. Pions are considered in the structureless limit and, besides the chiral invariant terms that reproduce previously derived expressions, symmetry breaking terms are also presented. The leading chiral quark-quark effective couplings are also found corresponding to a NJL and a vector-NJL couplings. All the resulting effective coupling constants and parameters are expressed in terms of the current and constituent quark masses and of the coupling g.
Interaction of acoustic waves generated by coupled plate
NASA Technical Reports Server (NTRS)
Cuschieri, J. M.
1990-01-01
When two substructures are coupled, the acoustic field generated by the motion of each of the substructures will interact with the motion of the other substructure. This would be the case of a structure enclosing an acoustic cavity. A technique to model the interaction of the generated sound fields from the two components of a coupled structure, and the influence of this interaction on the vibration of the structural components is presented. Using a mobility power flow approach, each element of the substructure is treated independently both when developing the structural response and when determining the acoustic field generated by this component. The presence of the other substructural components is introduced by assuming these components to be rigid baffles. The excitation of one of the substructures is assumed to be by an incident acoustic wave which is dependent of the motion of the substructure. The sound field generated by the motion of the substructure is included in the solution of the response.
Feinberg, Mark E; Jones, Damon E; Granger, Douglas A; Bontempo, Daniel E
2013-11-01
The study examines whether anxiety or chronic relationship stress alter the way that couple conflict affects cortisol levels for women and men during the transition to parenthood. Saliva samples, assayed for cortisol, were collected before and after couple interaction from 128 heterosexual couples expecting their first child. Confirming prior research, expectant mothers had higher cortisol levels than their spouses, and gestational age was linked to women's cortisol level. Negativity during couple interaction was associated with greater cortisol reactivity for men, but not women. Tests of moderation indicated little relation between negativity and cortisol recovery for individuals with a low level of anxiety or little history of chronic arguing with the partner. However, among individuals with elevated levels of either of these two factors, negativity was linked to less cortisol recovery for men, but more cortisol recovery for women. Consistent results were also found for the relation between low warmth in the couple interaction and both reactivity and recovery for men and women high in anxiety. Future research should examine whether pregnancy is responsible for these different gender patterns, or whether the inhibition of negativity is stressful for women with high levels of risk. PMID:24094282
Effective coupling for open billiards
NASA Astrophysics Data System (ADS)
Pichugin, Konstantin; Schanz, Holger; Šeba, Petr
2001-11-01
We derive an explicit expression for the coupling constants of individual eigenstates of a closed billiard that is opened by attaching a waveguide. The Wigner time delay and the resonance positions resulting from the coupling constants are compared to an exact numerical calculation. Deviations can be attributed to evanescent modes in the waveguide and to the finite number of eigenstates taken into account. The influence of the shape of the billiard and of the boundary conditions at the mouth of the waveguide are also discussed. Finally we show that the mean value of the dimensionless coupling constants tends to the critical value when the eigenstates of the billiard follow random-matrix theory.
An interacting dark energy model with nonminimal derivative coupling
NASA Astrophysics Data System (ADS)
Nozari, Kourosh; Behrouz, Noushin
2016-09-01
We study cosmological dynamics of an extended gravitational theory that gravity is coupled non-minimally with derivatives of a dark energy component and there is also a phenomenological interaction between the dark energy and dark matter. Depending on the direction of energy flow between the dark sectors, the phenomenological interaction gets two different signs. We show that this feature affects the existence of attractor solution, the rate of growth of perturbations and stability of the solutions. By considering an exponential potential as a self-interaction potential of the scalar field, we obtain accelerated scaling solutions that are attractors and have the potential to alleviate the coincidence problem. While in the absence of the nonminimal derivative coupling there is no attractor solution for phantom field when energy transfers from dark matter to dark energy, we show an attractor solution exists if one considers an explicit nonminimal derivative coupling for phantom field in this case of energy transfer. We treat the cosmological perturbations in this setup with details to show that with phenomenological interaction, perturbations can grow faster than the minimal case.
SynCoPation: Interactive Synthesis-Coupled Sound Propagation.
Rungta, Atul; Schissler, Carl; Mehra, Ravish; Malloy, Chris; Lin, Ming; Manocha, Dinesh
2016-04-01
Recent research in sound simulation has focused on either sound synthesis or sound propagation, and many standalone algorithms have been developed for each domain. We present a novel technique for coupling sound synthesis with sound propagation to automatically generate realistic aural content for virtual environments. Our approach can generate sounds from rigid-bodies based on the vibration modes and radiation coefficients represented by the single-point multipole expansion. We present a mode-adaptive propagation algorithm that uses a perceptual Hankel function approximation technique to achieve interactive runtime performance. The overall approach allows for high degrees of dynamism - it can support dynamic sources, dynamic listeners, and dynamic directivity simultaneously. We have integrated our system with the Unity game engine and demonstrate the effectiveness of this fully-automatic technique for audio content creation in complex indoor and outdoor scenes. We conducted a preliminary, online user-study to evaluate whether our Hankel function approximation causes any perceptible loss of audio quality. The results indicate that the subjects were unable to distinguish between the audio rendered using the approximate function and audio rendered using the full Hankel function in the Cathedral, Tuscany, and the Game benchmarks. PMID:26780813
3D RNA and Functional Interactions from Evolutionary Couplings.
Weinreb, Caleb; Riesselman, Adam J; Ingraham, John B; Gross, Torsten; Sander, Chris; Marks, Debora S
2016-05-01
Non-coding RNAs are ubiquitous, but the discovery of new RNA gene sequences far outpaces the research on the structure and functional interactions of these RNA gene sequences. We mine the evolutionary sequence record to derive precise information about the function and structure of RNAs and RNA-protein complexes. As in protein structure prediction, we use maximum entropy global probability models of sequence co-variation to infer evolutionarily constrained nucleotide-nucleotide interactions within RNA molecules and nucleotide-amino acid interactions in RNA-protein complexes. The predicted contacts allow all-atom blinded 3D structure prediction at good accuracy for several known RNA structures and RNA-protein complexes. For unknown structures, we predict contacts in 160 non-coding RNA families. Beyond 3D structure prediction, evolutionary couplings help identify important functional interactions-e.g., at switch points in riboswitches and at a complex nucleation site in HIV. Aided by increasing sequence accumulation, evolutionary coupling analysis can accelerate the discovery of functional interactions and 3D structures involving RNA. PMID:27087444
Proxemics in Couple Interactions: Rekindling an Old Optic.
Sluzki, Carlos E
2016-03-01
Utilizing as a lens the interpersonal implications of physical interpersonal distances in social contexts (a set of variables present during the professional discourse during the 1960s and 1970s, to then fade away), this article explores interactive process displayed by the protagonic couple in Bela Bartok's opera "Bluebeard Castle," an exercise aimed at underlining the value of maintaining proxemics as an explicit level of observation for clinical practice and interpersonal research. PMID:26558850
McKay, Garrett; Couch, Kylie D; Mezyk, Stephen P; Rosario-Ortiz, Fernando L
2016-08-01
We studied the formation of photochemically produced reactive intermediates (RI) from dissolved organic matter (DOM). Specifically, we focused on the effects of variable molecular weight and chemical reduction on the optical properties of DOM (absorbance and fluorescence) and the formation of singlet oxygen ((1)O2), DOM triplet excited states ((3)DOM*), and the hydroxyl radical ((•)OH). The data are largely evaluated in terms of a charge-transfer (CT) model, but deficiencies in the model to explain the data are pointed out when evident. A total of two sets of samples were studied that were subjected to different treatments; the first set included secondary-treated wastewaters and a wastewater-impacted stream, and the second was a DOM isolate. Treatments included size fractionation and chemical reduction using sodium borohydride. Taken as a whole, the results demonstrate that decreasing molecular weight and borohydride reduction work in opposition regarding quantum efficiencies for (1)O2 and (3)DOM* production but in concert for fluorescence and (•)OH production. The optical and photochemical data provide evidence for a limited role of CT interactions occurring in lower-molecular-weight DOM molecules. In addition, the data suggest that the observed optical and photochemical properties of DOM are a result of multiple populations of chromophores and that their relative contribution is changed by molecular-weight fractionation and borohydride reduction. PMID:27377760
Strongly coupled large N spectrum of two matrices coupled via a Yang-Mills interaction
Cook, Martin N. H.; Rodrigues, Joao P.
2008-09-15
We consider the large N spectrum of the quantum mechanical Hamiltonian of two Hermitian matrices coupled via a Yang-Mills interaction. In a framework where one of the matrices is treated exactly and the other is treated as a creation operator impurity, the difference equation associated with the Yang-Mills interaction is derived and solved exactly for two impurities. In this case, the full string tension corrected spectrum depends on two momenta. For a specific value of one of these momenta, the spectrum has the same structure as that of giant magnon bound states. States with general number of impurities are also discussed.
Dzyaloshinskii-Moriya Interaction and Spiral Order in Spin-orbit Coupled Optical Lattices
Gong, Ming; Qian, Yinyin; Yan, Mi; Scarola, V. W.; Zhang, Chuanwei
2015-01-01
We show that the recent experimental realization of spin-orbit coupling in ultracold atomic gases can be used to study different types of spin spiral order and resulting multiferroic effects. Spin-orbit coupling in optical lattices can give rise to the Dzyaloshinskii-Moriya (DM) spin interaction which is essential for spin spiral order. By taking into account spin-orbit coupling and an external Zeeman field, we derive an effective spin model in the Mott insulator regime at half filling and demonstrate that the DM interaction in optical lattices can be made extremely strong with realistic experimental parameters. The rich finite temperature phase diagrams of the effective spin models for fermions and bosons are obtained via classical Monte Carlo simulations. PMID:26014458
The validity of retrospectively reported conflict interactions in couples.
Backer-Fulghum, Lindsey M; Sanford, Keith
2015-04-01
This study investigated the extent to which researchers and clinicians can obtain valid retrospective self-reports of couples' conflict interactions outside a laboratory setting. A distinction was made between relationship attribute variance, regarding a shared perspective of both partners, and informant-specific variance, regarding the unique vantage point of each partner. By examining convergent and divergent associations for each type of variance, this study clarified the risk that responses might be influenced by informant-specific biases related to levels of relationship satisfaction. This study also investigated potential moderators of validity. Participants included both members of 269 married and cohabiting couples (538 individuals) who completed online questionnaires. Results were analyzed using a correlated trait-correlated method minus one model. The total true variance included large components of both shared relationship attribute variance and informant-specific variance. Although the shared component was moderately correlated with relationship satisfaction, the informant-specific component was mostly distinct from satisfaction, suggesting minimal bias. Convergent correlations between partners were strong and mostly unrelated to potential moderating variables, albeit slightly smaller than reported in studies conducted in laboratory settings. The results generally support the validity for retrospective self-reports of conflict interactions, especially when reports are obtained from both members of a couple. PMID:25689089
The nonclassical effects in coupled optomechanical array
NASA Astrophysics Data System (ADS)
Zhou, Wenjun; Cheng, Jiong; Zhang, Wenzhao; Yousif, Taha; Zhou, Ling
2015-07-01
We investigate a coupled array of ? identical cavity optomechanical systems. By adiabatically eliminating the cavity fields, we derive an effective Hamiltonian of the ? phonon modes coupled via XX form. We show further that the coupled mechanical oscillators can be used to transmit state and the single mode of the oscillator and the two-mode of neighbor oscillators can exhibit squeezing simultaneously. Under the suitable regime of parameters, the phonon blockade is exhibited.
Inflationary magnetogenesis, derivative couplings, and relativistic Van der Waals interactions
NASA Astrophysics Data System (ADS)
Giovannini, Massimo
2015-08-01
When the gauge fields have derivative couplings to scalars, like in the case of the relativistic theory of Van der Waals (or Casimir-Polder) interactions, conformal invariance is broken but the magnetic and electric susceptibilities are not bound to coincide. We analyze the formation of large-scale magnetic fields in slow-roll inflation and find that they are generated at the level of a few hundredths of a nG and over typical length scales between few Mpc and 100 Mpc. Using a new time parametrization that reduces to conformal time but only for coincident susceptibilities, the gauge action is quantized while the evolution equations of the corresponding mode functions are more easily solvable. The power spectra depend on the normalized rates of variation of the two susceptibilities (or of the corresponding gauge couplings) and on the absolute value of their ratio at the beginning of inflation. We pin down explicit regions in the parameter space where all the physical requirements (i.e., the backreaction constraints, the magnetogenesis bounds and the naturalness of the initial conditions of the scenario) are jointly satisfied. Weakly coupled initial data are favored if the gauge couplings are of the same order at the end of inflation. Duality is systematically used to simplify the analysis of the wide parameter space of the model.
Fractional dynamics of coupled oscillators with long-range interaction
Tarasov, Vasily E.; Zaslavsky, George M.
2006-06-15
We consider a one-dimensional chain of coupled linear and nonlinear oscillators with long-range powerwise interaction. The corresponding term in dynamical equations is proportional to 1/|n-m|{sup {alpha}}{sup +1}. It is shown that the equation of motion in the infrared limit can be transformed into the medium equation with the Riesz fractional derivative of order {alpha}, when 0<{alpha}<2. We consider a few models of coupled oscillators and show how their synchronization can appear as a result of bifurcation, and how the corresponding solutions depend on {alpha}. The presence of a fractional derivative also leads to the occurrence of localized structures. Particular solutions for fractional time-dependent complex Ginzburg-Landau (or nonlinear Schroedinger) equation are derived. These solutions are interpreted as synchronized states and localized structures of the oscillatory medium.
Snapin interacts with G-protein coupled receptor PKR2.
Song, Jian; Li, Jie; Liu, Hua-die; Liu, Wei; Feng, Yong; Zhou, Xiao-Tao; Li, Jia-Da
2016-01-15
Mutations in Prokineticin receptor 2 (PKR2), a G-protein-coupled receptor, have been identified in patients with Kallmann syndrome and/or idiopathic hypogonadotropic hypogonadism, characterized by delayed puberty and infertility. In this study, we performed yeast two-hybrid screening by using PKR2 C-terminus (amino acids 333-384) as a bait, and identified Snapin as a novel interaction partner for PKR2. The interaction of Snapin and PKR2 was confirmed in GST pull-down and co-immunoprecipitation studies. We further demonstrated that two α-helix domains in Snapin are required for the interaction. And the interactive motifs of PKR2 were mapped to YFK (343-345) and HWR (351-353), which shared a similar sequence of two aromatic amino acids followed by a basic amino acid. Disruption of Snapin-PKR2 interaction did not affect PKR2 signaling, but increased the ligand-induced degradation, implying a role of Snapin in the trafficking of PKR2. PMID:26687946
Controllable electron interactions in quantum dots coupled to nanowires
NASA Astrophysics Data System (ADS)
Tacla, Alexandre; Cheng, Guanglei; Tomczyk, Michelle; Levy, Jeremy; Daley, Andrew; Pekker, David
We theoretically study transport properties in quantum dot devices proximity coupled to superconducting nanowires. In particular, we investigate the controllable transition from resonant pair tunneling to Andreev bound states, which has been recently observed in nanodevices fabricated at the interface of the oxide heterostructure LaAlO3/SrTiO3. We show that such a transition in transport features can signify a Lifshitz transition, at which electron interactions change from attractive to repulsive. We also discuss an alternate description in terms of magnetic impurities.
Working Effectively and Efficiently with Couples.
ERIC Educational Resources Information Center
Lazarus, Arnold A.
2000-01-01
Discusses several myths and underscores some active ingredients of couples counseling. The adjunctive value of bibliotherapy is presented and the interactions among such components as similarity, compatibility, mood, disposition, temperament, and communication are elucidated. Clinical vignettes illustrate several crucial issues and principles.…
Smart sensing of tool/tissue interaction by resistive coupling.
Yoshimoto, Shunsuke; Kuroda, Yoshihiro; Imura, Masataka; Oshiro, Osamu; Sato, Kosuke
2013-01-01
A smart sensing of tool-tissue interaction is required to monitor the surgical task without disturbing the tool manipulation. We proposed a new tactile sensing method that enables us to detect the tool-tissue interaction with a simple hardware by resistive coupling. The system consists of two electrodes, a bridge circuit and a differential amplifier for the robust sensing of the contact resistance between the tool and tissue. In order to evaluate the sensing method, we investigated the relationship between the sensor output and the deformation of a wet sponge sample by retraction task. According to the model fitting of the deformation-output profile, we concluded that the proposed sensor provide enough reproducibility in the simple situation. Furthermore, we confirmed that the developed sensor works with a biological sample. PMID:24109765
Magnetic interactions in exchange-coupled yet unbiased IrMn/NiCu bilayers.
Cichelero, R; Harres, A; Sossmeier, K D; Schmidt, J E; Geshev, J
2013-10-23
This paper reports experimental and model magnetization results obtained on exchange-coupled ferromagnet/antiferromagnet (FM/AF) bilayers that show zero net bias. The coercivity of the films, either irradiated with He or implanted with Ge ions at 40 keV, varies significantly with the fluence used. We employed the remanence plots technique in order to estimate the nature of the interactions present and check if there exists a correlation between their type and the coercivity variations. The analysis of the remanence plots through numerical simulations based on the Landau-Lifshitz-Gilbert equation demonstrated that outcomes of interactions within the FM layer could be distinguished from those coming from coupling at the FM/AF interface and that demagnetizing interaction effects could be achieved without the presence of dipolar interactions. Our findings indicate that such experiments could give selective information on modifications caused by a post-deposition treatment in each layer of the film. PMID:24065441
Limits on Higgs boson couplings in Effective field theory
NASA Astrophysics Data System (ADS)
Belyaev, N.; Reid, T.
2016-02-01
We review the Effective Field Theory (EFT) to make projections on physics beyond the Standard Model in the Higgs sector. We provide relations between the non-Standard Model couplings of the Strongly-Interacting Light Higgs (SILH) effective Lagrangian implemented in the eHDecay package and the corresponding terms of the spin-0 Higgs Characterisation model's effective Lagrangian used with the aMC@NLO Monte Carlo generator. Constraints on BSM couplings are determined on the basis of existing experimental limits on Higgs boson width and branching ratios.
Modeling the interaction between two dimensional strongly coupled confined dust clusters
Djebli, M.; Issaad, M.; Rouaiguia, L.
2010-03-15
Numerical simulations based on the Monte Carlo method are conducted to investigate ground-state configurations and phase transitions of strongly coupled dust particles. The interaction between negatively charged dust particles is modeled by three different potentials, namely, Coulomb, Yukawa, and logarithmic. The effect of random charge fluctuation is taken into account for a dominant charging process by particles collection and in the presence of two dimensional parabolic confinement potential. Structural arrangement and phase transition are found to be dependent on the potential interaction and the charge fluctuation. The changes in the melting temperature, when the charge fluctuation is taken into account, are particularly noticeable for systems with particles interacting through logarithmic potential.
NASA Astrophysics Data System (ADS)
Bukač, M.
2016-05-01
We model the interaction between an incompressible, viscous fluid, thin elastic structure and a poroelastic material. The poroelastic material is modeled using the Biot's equations of dynamic poroelasticity. The fluid, elastic structure and the poroelastic material are fully coupled, giving rise to a nonlinear, moving boundary problem with novel energy estimates. We present a modular, loosely coupled scheme where the original problem is split into the fluid sub-problem, elastic structure sub-problem and poroelasticity sub-problem. An energy estimate associated with the stability of the scheme is derived in the case where one of the coupling parameters, β, is equal to zero. We present numerical tests where we investigate the effects of the material properties of the poroelastic medium on the fluid flow. Our findings indicate that the flow patterns highly depend on the storativity of the poroelastic material and cannot be captured by considering fluid-structure interaction only.
NASA Astrophysics Data System (ADS)
Abdalla, M. Sebawe; Ahmed, M. M. A.; Khalil, E. M.; Obada, A. S.-F.
2016-01-01
We introduce the problem of three types of interaction between an N-level quantum system and a two-level atom where three coupling parameters are involved. The system can be deduced from the Heisenberg chain. The canonical transformation is used to remove two coupling parameters from the system and consequently it is reduced to atom-atom interaction. The wave function is calculated using the evolution operator and hence we have managed to obtain the expectation value of some dynamical operators. During our study of the atomic inversion we noted that the collapses period is shifted up when we take the effect of λ2 into consideration. While it is shifted up and down in the presence of λ3. The atomic angle plays a crucial role for controlling the degree of entanglement. For the variance squeezing we noted that the coupling parameter λ2 shows amounts of squeezing more than the case of λ3. Similar behavior is noted for the entropy squeezing.
Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots
NASA Astrophysics Data System (ADS)
Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.
2016-08-01
In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.
Weighty dynamics: exploring couples' perceptions of post-weight-loss interaction.
Romo, Lynsey Kluever; Dailey, René M
2014-01-01
Although romantic couples can use communication to help one another lose weight and maintain weight loss, the effect of weight loss on partner interaction is less understood. However, an examination of the interpersonal context in which partners manage their weight is important to help partners negotiate their weight, their relationship, and the U.S. obesity epidemic. Guided by systems theory, this study explored partners' perceptions of post-weight-loss interaction in relationships in which one partner lost weight and the other did not. Through qualitative questionnaires of 42 adults (21 romantic couples), the dyadic investigation revealed that while losing weight resulted in positive interaction for many partners (e.g., engaging in a shared healthy lifestyle), shedding weight also yielded some negative consequences (e.g., non-weight-loss partner criticism). The extent to which partners embraced new weight management rules and patterns largely influenced post-weight-loss communication and behavior. PMID:24156394
Controlled Crystallinity and Fundamental Coupling Interactions in Nanocrystals
NASA Astrophysics Data System (ADS)
Ouyang, Min
2009-03-01
Metal and semiconductor nanocrystals show many unusual properties and functionalities, and can serve as model system to explore fundamental quantum and classical coupling interactions as well as building blocks of many practical applications. However, because of their small size, these nanoparticles typically exhibit different crystalline properties as compared with their bulk counterpart, and controlling crystallinity (and structural defects) within nanoparticles has posed significant technical challenges. In this talk, I will firstly apply silver metal nanoparticles as an example and present a novel chemical synthetic technique to achieve unprecedented crystallinity control at the nanoscale. This engineering of nanocrystallinity enables manipulation of intrinsic chemical functionalities, physical properties as well as nano-device performance [1]. For example, I will highlight that electron- phonon coupling constant can be significantly reduced by about four times and elastic modulus is increased ˜40% in perfect single crystalline silver nanoparticles as compared with those in disordered twinned nanoparticles. One important application of metal nanoparticles is nanoscale sensors. I will thus demonstrate that performance of nanoparticles based molecular sensing devices can be optimized with three times improvement of figure-of-merit if perfect single crystalline nanoparticles are applied. Lastly, I will present our related studies on semiconductor nanocrystals as well as their hybrid heterostructures. These discussions should offer important implications for our understanding of the fundamental properties at nanoscale and potential applications of metal nanoparticles. [4pt] [1] Yun Tang and Min Ouyang, Nature Materials, 6, 754, 2007.
Effect of nonlinear nonlinear coupling to a pure dephasing model
NASA Astrophysics Data System (ADS)
Ge, Li; Zhao, Nan
2015-03-01
We investigate the influence of the nonlinear coupling to the coherence of a pure dephasing model. The total system consists of a qubit and a Bosonic bath, which are coupled by an interaction HI =g1σz ⊗ x +g2σz ⊗x2 with x =1/√{ 2} (a +a†) . It's shown that no matter how small g2 is, the long time behavior of the coherence is significantly changed by the nonlinear coupling for free induction decay (FID), while the effect of g1 can be neglected as long as g1 is much smaller than the enegy splitting of the qubit. In the case that many-pulse dynamical decoupling control is exerted on the qubit, g2 also modulates the oscillation of the coherence. Our results indicate that the nonlinear coupling must be taken into account for long time dynamics.
Decoherence of a single spin coupled to an interacting spin bath
NASA Astrophysics Data System (ADS)
Wu, Ning; Fröhling, Nina; Xing, Xi; Hackmann, Johannes; Nanduri, Arun; Anders, Frithjof B.; Rabitz, Herschel
2016-01-01
Decoherence of a central spin coupled to an interacting spin bath via inhomogeneous Heisenberg coupling is studied by two different approaches, namely an exact equations of motion (EOMs) method and a Chebyshev expansion technique (CET). By assuming a wheel topology of the bath spins with uniform nearest-neighbor X X -type intrabath coupling, we examine the central spin dynamics with the bath prepared in two different types of bath initial conditions. For fully polarized baths in strong magnetic fields, the polarization dynamics of the central spin exhibits a collapse-revival behavior in the intermediate-time regime. Under an antiferromagnetic bath initial condition, the two methods give excellently consistent central spin decoherence dynamics for finite-size baths of N ≤14 bath spins. The decoherence factor is found to drop off abruptly on a short time scale and approach a finite plateau value which depends on the intrabath coupling strength nonmonotonically. In the ultrastrong intrabath coupling regime, the plateau values show an oscillatory behavior depending on whether N /2 is even or odd. The observed results are interpreted qualitatively within the framework of the EOM and perturbation analysis. The effects of anisotropic spin-bath coupling and inhomogeneous intrabath bath couplings are briefly discussed. Possible experimental realization of the model in a modified quantum corral setup is suggested.
Tensor coupling effect on relativistic symmetries
NASA Astrophysics Data System (ADS)
Chen, ShouWan; Li, DongPeng; Guo, JianYou
2016-08-01
The similarity renormalization group is used to transform the Dirac Hamiltonian with tensor coupling into a diagonal form. The upper (lower) diagonal element becomes a Schr¨odinger-like operator with the tensor component separated from the original Hamiltonian. Based on the operator, the tensor effect of the relativistic symmetries is explored with a focus on the single-particle energy contributed by the tensor coupling. The results show that the tensor coupling destroying (improving) the spin (pseudospin) symmetry is mainly attributed to the coupling of the spin-orbit and the tensor term, which plays an opposite role in the single-particle energy for the (pseudo-) spin-aligned and spin-unaligned states and has an important influence on the shell structure and its evolution.
Spin-Orbit Coupling, Strong Interactions, and Topological Character
NASA Astrophysics Data System (ADS)
Pickett, Warren E.
In recent years the electronic structure of crystalline solids has come under close scrutiny because of the various types of topological characters that may arise. Most of the work is done at the one-electron (non-interacting) level, and most innovations have arisen from model tight-binding Hamiltonians and their eigenvectors. This talk will focus on a few examples of discoveriesmadecomputationally through DFT studies of actual materials, thus providing a physical realization as the discovery was made. Competition and partnership between strong interactions and spin-orbit coupling will be emphasized. Examples will include (1) the 'semi-Dirac' point Fermi surface phase in VO2 thin films, the first member of a class now called multi Weyl : massive in some direction, massless in other direction; (2) a nodal loop semimetal phase found in computational studies of thin SrVO3 films, realized more recently in NbP etc.; (3) the buckled honeycomb lattice of a (111) bilayer of LaMnO3 encased on LaAlO3, which is a Chern insulator and may be a realization of the Weyl-Mott insulator proposed recently by Morimoto and Nagaosa. Acknowledgments: R. Pentcheva, V. Pardo, K.-W. Lee, S. Gangopadhyay. DOE Grant DE-FG02-04ER46111.
Fully coupled resonant-triad interaction in an adverse-pressure-gradient boundary layer
NASA Technical Reports Server (NTRS)
Goldstein, M. E.; Lee, Sang S.
1992-01-01
The nonlinear resonant-triad interaction, proposed by Raetz (1959), Craik (1971), and others for a Blasius boundary layer, is analyzed here for an adverse-pressure-gradient boundary layer. We assume that the adverse pressure gradient is in some sense weak and, therefore, that the instability growth rate is small. This ensures that there is a well-defined critical layer located somewhere within the flow and that the nonlinear interaction is effectively confined to that layer. The initial interaction is of the parametric resonance type, even when the modal amplitudes are all of the same order. This means that the oblique instability waves exhibit faster than exponential growth and that the growth rate of the two-dimensional mode remains linear. However, the interaction and the resulting growth rates become fully coupled, once oblique-mode amplitudes become sufficiently large, but the coupling terms are now quartic, rather than quadratic as in the Craik (1971) analysis. More importantly, however, new nonlinear interactions, which were not present in the Craik-type analyses, now come into play. These interactions eventually have a dominant effect on the instability wave development.
Partition function corrections. [vibration-rotation interaction coupling in diatomic molecules
NASA Technical Reports Server (NTRS)
1976-01-01
The vibration-rotation interaction coupling in diatomic molecules is analyzed and first-order expressions for the energy levels are deduced. Corrections to the partition function to account for this coupling are derived. The effects of long-range intermolecular forces due to induced dipole-induced dipole interactions, dipole-induced dipole interactions, charge-dipole interactions, and charge-charge interactions are considered. London's quantized oscillator model of the induced dipole-induced dipole interaction is developed. The partition function including effects of such dispersion forces is derived and is shown to lead to the virial equation of state. For a model combining the hard sphere and long-range attractive type potentials, this is found to lead to the van der Waals equation of state. The equation of state near the critical point is presented in reduced form (thermodynamic variables expressed in units of critical point values). Finally, approximate corrections to the electronic partition functions are derived to account for perturbations of excited electronic states induced by neighboring neutral particles, heavy ions, and fast electron collisions.
NASA Astrophysics Data System (ADS)
Rajput, Gagan; Kumar, Rajendra; Ajay
2014-09-01
Using non-equilibrium Green's function approach, we study electronic transport through a parallel double quantum dot (DQD) system symmetrically coupled to conventional superconducting leads. Andreev bound states (ABS) and corresponding resonant Cooper pair electron transmission through such a DQD-superconductor tunnel junction around the Fermi energy, a manifestation of Josephson effect, occur due to proximity effect as a result of superconducting order parameter. Interdot tunnel coupling in parallel coupled DQD system and Coulomb interactions regulate the Josephson effect in a very significant manner. Further, it is also found that interdot tunnel coupling has reverse effect on ABS and Cooper pair tunneling in the presence and absence of Coulomb interactions.
Relativistic K-LL Auger spectra in the intermediate-coupling scheme with configuration interaction
NASA Technical Reports Server (NTRS)
Chen, M. H.; Crasemann, B.; Mark, H.
1980-01-01
Theoretical K-LL Auger spectra from relativistic Dirac-Hartree-Slater calculations in intermediate coupling with configuration interaction (ICWCI) are considered. Calculated transition rates for 25 elements with Z between 18 and 96, inclusive, are listed and compare well with experimental data. Relativistic effects are found to be important above Z equal to about 35, and ICWCI is necessary to describe the spectra for Z less than about 60.
Pressure effects in multiphase binary diffusion couples
NASA Astrophysics Data System (ADS)
Subramanyam, Dilip; Notis, Michael R.; Goldstein, Joseph I.
1985-04-01
A systematic study has been carried out of the effect of pressure upon growth kinetics of intermediate phases formed in diffusion couples in the binary systems Ni-Al, U-A1, and U-Cu. Even though applied pressures greater than 100 MPa and long times were investigated little or no pressure effect was observed, in disagreement with previous literature reports. The magnitude of observed pressure effects falls within that expected by closure of Kirkendall porosity.
Effect of interlayer exchange coupling on magnetic chiral structures
Kang, S. P.; Kwon, H. Y.; Kim, H. S.; Shim, J. H.; Won, C.
2015-07-28
We numerically investigated the effect of interlayer exchange coupling on magnetic chiral structures, such as a helical/cycloidal spin structure and magnetic skyrmion crystal (SkX), which are produced in a magnetic system involving the Dzyaloshinskii-Moriya interaction (DMI). We report the existence of a phase transition where the length scale of magnetic structure discontinuously changes, and that there can be a novel magnetic structure around the phase boundary that exhibits double-ordering lengths of magnetic structure. Therefore, the system has multiple ground phases determined by the ratio of interlayer exchange coupling strength and DMI strength. Furthermore, we investigated the critical condition of the external perpendicular field required for the SkX. The critical field is significantly reduced under the effect of interlayer exchange coupling, which can stabilize the SkX without the external field.
Interaction of G protein coupled receptors and cholesterol.
Gimpl, Gerald
2016-09-01
G protein coupled receptors (GPCRs) form the largest receptor superfamily in eukaryotic cells. Owing to their seven transmembrane helices, large parts of these proteins are embedded in the cholesterol-rich plasma membrane bilayer. Thus, GPCRs are always in proximity to cholesterol. Some of them are functionally dependent on the specific presence of cholesterol. Over the last years, enormous progress on receptor structures has been achieved. While lipophilic ligands other than cholesterol have been shown to bind either inside the helix bundle or at the receptor-lipid interface, the binding site of cholesterol was either a single transmembrane helix or a groove between two or more transmembrane helices. A clear preference for one of the two membrane leaflets has not been observed. Not surprisingly, many hydrophobic residues (primarily leucine and isoleucine) were found to be involved in cholesterol binding. In most cases, the rough β-face of cholesterol contacted the transmembrane helix bundle rather than the surrounding lipid matrix. The polar hydroxy group of cholesterol was localized near the water-membrane interface with potential hydrogen bonding to residues in receptor loop regions. Although a canonical motif, designated as CCM site, was detected as a specific cholesterol binding site in case of the β2AR, this site was not found to be occupied by cholesterol in other GPCRs possessing the same motif. Cholesterol-receptor interactions can increase the compactness of the receptor structure and are able to enhance the conformational stability towards active or inactive receptor states. Overall, all current data suggest a high plasticity of cholesterol interaction sites in GPCRs. PMID:27108066
Transition-density-fragment interaction approach for exciton-coupled circular dichroism spectra
NASA Astrophysics Data System (ADS)
Fujimoto, Kazuhiro J.
2010-09-01
A transition-density-fragment interaction (TDFI) method for exciton-coupled circular dichroism (ECCD) spectra is proposed. The TDFI method was previously developed for excitation-energy transfer, which led to the successful estimation of the electronic coupling energy between donor and accepter molecules in xanthorhodopsin [K. J. Fujimoto and S. Hayashi, J. Am. Chem. Soc. 131, 14152 (2009)]. In the present study, the TDFI scheme is extended to the ECCD spectral calculation based on the matrix method and is applied to a dimerized retinal (all-trans N-retinylidene-L-alanine Schiff base) chromophore. Compared with the dipole-dipole and transition charge from ESP methods, TDFI has a much improved description of the electronic coupling. In addition, the matrix method combined with TDFI can reduce the computational costs compared with the full quantum-mechanical calculation. These advantages of the present method make it possible to accurately evaluate the CD Cotton effects observed in experiment.
Spatial resolution effect of light coupling structures
NASA Astrophysics Data System (ADS)
Li, Juntao; Li, Kezheng; Schuster, Christian; Su, Rongbin; Wang, Xuehua; Borges, Ben-Hur V.; Krauss, Thomas F.; Martins, Emiliano R.
2015-12-01
The coupling of light between free space and thin film semiconductors is an essential requirement of modern optoelectronic technology. For monochromatic and single mode devices, high performance grating couplers have been developed that are well understood. For broadband and multimode devices, however, more complex structures, here referred to as “coupling surfaces”, are required, which are often difficult to realise technologically. We identify general design rules based on the Fourier properties of the coupling surface and show how they can be used to determine the spatial resolution required for the coupler’s fabrication. To our knowledge, this question has not been previously addressed, but it is important for the understanding of diffractive nanostructures and their technological realisation. We exemplify our insights with solar cells and UV photodetectors, where high-performance nanostructures that can be realised cost-effectively are essential.
Spatial resolution effect of light coupling structures
Li, Juntao; Li, Kezheng; Schuster, Christian; Su, Rongbin; Wang, Xuehua; Borges, Ben-Hur V.; Krauss, Thomas F.; Martins, Emiliano R.
2015-01-01
The coupling of light between free space and thin film semiconductors is an essential requirement of modern optoelectronic technology. For monochromatic and single mode devices, high performance grating couplers have been developed that are well understood. For broadband and multimode devices, however, more complex structures, here referred to as “coupling surfaces”, are required, which are often difficult to realise technologically. We identify general design rules based on the Fourier properties of the coupling surface and show how they can be used to determine the spatial resolution required for the coupler’s fabrication. To our knowledge, this question has not been previously addressed, but it is important for the understanding of diffractive nanostructures and their technological realisation. We exemplify our insights with solar cells and UV photodetectors, where high-performance nanostructures that can be realised cost-effectively are essential. PMID:26678574
Rodrigues, Joao P.; Zaidi, Alia
2010-10-15
We derive a planar sector of the large N nonsupersymmetric background of the quantum mechanical Hamiltonian of two Hermitian matrices coupled via a Yang-Mills interaction, in terms of the density of eigenvalues of one of the matrices. This background satisfies an implicit nonlinear integral equation, with a perturbative small coupling expansion and a solvable large coupling solution, which is obtained. The energy of system and the expectation value of several correlators are obtained in this strong coupling limit. They are free of infrared divergences.
Strong coupling theory for electron-mediated interactions in double-exchange models
NASA Astrophysics Data System (ADS)
Ishizuka, Hiroaki; Motome, Yukitoshi
2015-07-01
We present a theoretical framework for evaluating effective interactions between localized spins mediated by itinerant electrons in double-exchange models. Performing the expansion with respect to the spin-dependent part of the electron hopping terms, we show a systematic way of constructing the effective spin model in the large Hund's coupling limit. As a benchmark, we examine the accuracy of this method by comparing the results with the numerical solutions for the spin-ice type model on a pyrochlore lattice. We also discuss an extension of the method to the double-exchange models with Heisenberg and X Y localized spins.
Decoherence dynamics of interacting qubits coupled to a bath of local optical phonons
NASA Astrophysics Data System (ADS)
Lone, Muzaffar Qadir; Yarlagadda, S.
2016-04-01
We study decoherence in an interacting qubit system described by infinite range Heisenberg model (IRHM) in a situation where the system is coupled to a bath of local optical phonons. Using perturbation theory in polaron frame of reference, we derive an effective Hamiltonian that is valid in the regime of strong spin-phonon coupling under nonadiabatic conditions. It is shown that the effective Hamiltonian commutes with the IRHM upto leading orders of perturbation and thus has the same eigenstates as the IRHM. Using a quantum master equation with Markovian approximation of dynamical evolution, we show that the off-diagonal elements of the density matrix do not decay in the energy eigen basis of IRHM.
Nap, R J; Szleifer, I
2013-08-01
One of the key challenges in the development of nano carriers for drug delivery and imaging is the design of a system that selectively binds to target cells. A common strategy is to coat the delivery device with specific ligands that bind strongly to overexpressed receptors. However such devices are usually unable to discriminate between receptors found on benign and malignant cells. We demonstrate, theoretically, how one can achieve enhanced binding to target cells by using multiple physical and chemical interactions. We study the effective interactions between a polymer decorated nano micelle or nanoparticle with three types of model lipid membranes that differ in the composition of their outer leaflet. They are: i) lipid membranes with overexpressed receptors, ii) membranes with a given fraction of negatively charged lipids and iii) membranes with both overexpressed receptors and negatively charged lipids. The coating contains a mixtures of two short polymers, one neutral for protection and the other a polybase with a functional end-group to optimize specific binding with the overexpressed receptors and electrostatic interactions with charged lipid head-groups. The strength of the binding for the combined system is much larger than the sum of the independent electrostatic or specific interactions binding. We find a range of distances where the addition of two effective repulsive interactions become an attraction in the combined case. The changes in the strength and shape of the effective interaction are due to the coupling that exists between molecular organization, physical interactions and chemical state, e.g., protonation. The predictions provide guidelines for the design of carrier devices for targeted drug and nanoparticle delivery and give insight in the competing and highly non-additive nature of the different effective interactions in nanoscale systems in constrained environments that are ubiquitous in synthetic and biological systems. PMID:23930222
Receptor-coupled effector systems and their interactions
Wiener, E.C.
1988-01-01
We investigated the modulation of intracellular signal generation by receptor-coupled effector systems in B lymphocytes, and whether these alterations are consistent with the effects of prostaglandins. TPA (12-O-tetradecanoyl phorbol-13-acetate) and sn-1,2,-dioctanoylglycerol (diC{sub 8}) substitute for lipid derived signals which activate protein kinase C. Pretreating splenocytes from athymic nude mice with 100nM TPA or 5 {mu}M diC{sub 8} potentiated the forskolin-induced increased in cAMP (measured by radioimmunoassay) 2.5 and 3.0 times (respectively), but they decreased the PGE{sub 1}-induced cAMP rise 48% and 35% (respectively). Goat anti-mouse IgM, which activates diacylglycerol production, potentiated the forskolin-induced cAMP increase by 76%, but reduced that of PGE{sub 1} by 30%. Rabbit anti-mouse IgG, its F(ab{prime}){sub 2} fragment, or goat anti-mouse IGM induced increases in the cytosolic free (Ca{sup 2+}), (Ca{sup 2+}){sub i}, which TPA inhibited. In contrast, TPA potential antibody-induced {sup 3}H-thymidine (85x) and {sup 3}H-uridine (30x) uptake in B lymphocytes.
Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots.
Keller, A J; Lim, J S; Sánchez, David; López, Rosa; Amasha, S; Katine, J A; Shtrikman, Hadas; Goldhaber-Gordon, D
2016-08-01
In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior. PMID:27541473
NASA Astrophysics Data System (ADS)
Nap, Rikkert; Szleifer, Igal
2014-03-01
A key challenge in nanomedicine is to design carrier system for drug delivery that selectively binds to target cells without binding to healthy cells. A common strategy is to end-functionalize the polymers coating of the delivery device with specific ligands that bind strongly to overexpressed receptors. Such devices are usually unable to discriminate between receptors found on benign and malignant cells. We demonstrate, theoretically, how one can achieve selective binding to target cells by using multiple physical and chemical interactions. We study the effective interactions between a polymer decorated nanosized micelle or solid nanoparticle with model lipid layers. The polymer coating contains a mixture of two polymers, one neutral for protection and the other a polybase with a functional end-group to optimize specific binding and electrostatic interactions with the charged lipid head-groups found on the lipid surface. The strength of the binding for the combined system is much larger than the sum of the independent electrostatic or specific ligand-receptor binding. The search for optimal binding conditions lead to the finding of a non-additive coupling that exists in systems where chemical equilibrium, molecular organization, and physical interactions are coupled together.
Smith, Timothy W.; Berg, Cynthia A.; Florsheim, Paul; Uchino, Bert N.; Pearce, Gale; Hawkins, Melissa; Henry, Nancy J.M.; Beveridge, Ryan M.; Skinner, Michelle A.; Olsen-Cerny, Chrisanna
2011-01-01
Prior theory and research regarding age differences in marital interaction suggest that older couples display and experience more positivity and less negativity than middle-aged couples. However, studies of overt behavior in older couples are relatively rare and have emphasized disagreement, neglecting other important contexts for older couples such as collaboration during everyday problem solving. Further, the affiliation or communion dimension of social interaction (i.e., warmth vs. hostility) is commonly assessed, but not the control or agency dimension (e.g., dominance vs. submissiveness). The present study examined affect, cognitive appraisals, and overt behavior during disagreement (i.e., discussing a current conflict) and collaboration (i.e., planning errands) in 300 middle-aged and older married couples. Older couples reported less negative affect during disagreement and rated spouses as warmer than did middle-aged couples. However, these effects were eliminated when older couples’ greater marital satisfaction was controlled. For observed behavior, older couples displayed little evidence of greater positivity and reduced negativity – especially women. During collaboration, older couples displayed a unique blend of warmth and control, suggesting a greater focus on emotional and social concerns during problem solving. PMID:19485646
NASA Astrophysics Data System (ADS)
Mu-Tian, Cheng; Wei-Wei, Zong; Gen-Long, Ye; Xiao-San, Ma; Jia-Yan, Zhang; Bing, Wang
2016-06-01
We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission and reflection amplitudes of the propagating single photon in the waveguide are obtained. The influence of the coupling strength between the nanocavity and the external mirror on the single photon scattering spectra is discussed. We also extend the results to the waveguide with linear and quadratic form dispersion relations. Supported by the National Natural Science Foundation of China under Grant Nos. 11105001 and 61472282, the Anhui Provincial Natural Science Foundation under Grant Nos. 1408085QA22, 1608085MA09, and 1508085MF129.
The competition of particle-vibration coupling and tensor interaction in spherical nuclei
NASA Astrophysics Data System (ADS)
Afanasjev, Anatoli; Litvinova, Elena
2014-09-01
The search for missing terms in the energy density functionals (EDF) is one of the leading directions in the development of nuclear density functional theory (DFT). Tensor force is one of possible candidates. However, despite extensive studies the questions about its effective strength and unambiguous signals still remain open. One of the main experimental benchmarks for the studies of tensor interaction is provided by the data on the single-particle states in the N = 82 and Z = 50 isotopes. The energy splittings of the proton h11 / 2 and g7 / 2 states in the Z = 50 isotopes and neutron 1i13 / 2 and 1h9 / 2 states in the N = 82 isotones are used in the definition of tensor force in the Skyrme DFT. However, in experiment these states are not ``mean-field'' states because of coupling with vibrations. Employing relativistic particle-vibration coupling (PVC) model we show that many features of these splittings can be reproduced when PVC is taken into account. This suggests the competition of PVC and tensor interaction and that tensor interaction should be weaker as compared with previous estimates. The search for missing terms in the energy density functionals (EDF) is one of the leading directions in the development of nuclear density functional theory (DFT). Tensor force is one of possible candidates. However, despite extensive studies the questions about its effective strength and unambiguous signals still remain open. One of the main experimental benchmarks for the studies of tensor interaction is provided by the data on the single-particle states in the N = 82 and Z = 50 isotopes. The energy splittings of the proton h11 / 2 and g7 / 2 states in the Z = 50 isotopes and neutron 1i13 / 2 and 1h9 / 2 states in the N = 82 isotones are used in the definition of tensor force in the Skyrme DFT. However, in experiment these states are not ``mean-field'' states because of coupling with vibrations. Employing relativistic particle-vibration coupling (PVC) model we show that
Effective field theory of quantum gravity coupled to scalar electrodynamics
NASA Astrophysics Data System (ADS)
Ibiapina Bevilaqua, L.; Lehum, A. C.; da Silva, A. J.
2016-05-01
In this work, we use the framework of effective field theory to couple Einstein’s gravity to scalar electrodynamics and determine the renormalization of the model through the study of physical processes below Planck scale, a realm where quantum mechanics and general relativity are perfectly compatible. We consider the effective field theory up to dimension six operators, corresponding to processes involving one-graviton exchange. Studying the renormalization group functions, we see that the beta function of the electric charge is positive and possesses no contribution coming from gravitational interaction. Our result indicates that gravitational corrections do not alter the running behavior of the gauge coupling constants, even if massive particles are present.
Du, Mao-Hua
2015-04-02
We know that native point defects play an important role in carrier transport properties of CH3NH3PbI3. However, the nature of many important defects remains controversial due partly to the conflicting results reported by recent density functional theory (DFT) calculations. In this Letter, we show that self-interaction error and the neglect of spin–orbit coupling (SOC) in many previous DFT calculations resulted in incorrect positions of valence and conduction band edges, although their difference, which is the band gap, is in good agreement with the experimental value. Moreover, this problem has led to incorrect predictions of defect-level positions. Hybrid density functional calculations, which partially correct the self-interaction error and include the SOC, show that, among native point defects (including vacancies, interstitials, and antisites), only the iodine vacancy and its complexes induce deep electron and hole trapping levels inside of the band gap, acting as nonradiative recombination centers.
Earthquake nucleation in a stochastic fault model of globally coupled units with interaction delays
NASA Astrophysics Data System (ADS)
Vasović, Nebojša; Kostić, Srđan; Franović, Igor; Todorović, Kristina
2016-09-01
In present paper we analyze dynamics of fault motion by considering delayed interaction of 100 all-to-all coupled blocks with rate-dependent friction law in presence of random seismic noise. Such a model sufficiently well describes a real fault motion, whose prevailing stochastic nature is implied by surrogate data analysis of available GPS measurements of active fault movement. Interaction of blocks in an analyzed model is studied as a function of time delay, observed both for dynamics of individual faults and phenomenological models. Analyzed model is examined as a system of all-to-all coupled blocks according to typical assumption of compound faults as complex of globally coupled segments. We apply numerical methods to show that there are local bifurcations from equilibrium state to periodic oscillations, with an occurrence of irregular aperiodic behavior when initial conditions are set away from the equilibrium point. Such a behavior indicates a possible existence of a bi-stable dynamical regime, due to effect of the introduced seismic noise or the existence of global attractor. The latter assumption is additionally confirmed by analyzing the corresponding mean-field approximated model. In this bi-stable regime, distribution of event magnitudes follows Gutenberg-Richter power law with satisfying statistical accuracy, including the b-value within the real observed range.
Linear theory of beam-wave interaction in double-slot coupled cavity travelling wave tube
NASA Astrophysics Data System (ADS)
Fang-ming, He; Wen-qiu, Xie; Ji-run, Luo; Min, Zhu; Wei, Guo
2016-03-01
A three-dimensional model of the double-slot coupled cavity slow-wave structure (CCSWS) with a solid round electron beam for the beam-wave interaction is presented. Based on the “cold” dispersion, the “hot” dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed. Project supported by the National Natural Science Foundation of China (Grant No. 11205162).
Microprobe PIXE study of Ni-Ge interactions in lateral diffusion couples
NASA Astrophysics Data System (ADS)
Chilukusha, D.; Pineda-Vargas, C. A.; Nemutudi, R.; Habanyama, A.; Comrie, C. M.
2015-11-01
Rutherford backscattering spectrometry on the nuclear microprobe (μRBS) is often used in studies of lateral diffusion couples. RBS requires that the positions of the interacting species on the periodic table are not too close in terms of atomic number and therefore do not produce excessive RBS peak overlap. In order to satisfactorily characterize systems that have atomic numbers which are close, it is necessary to find techniques which can complement μRBS. The aim of this study was to determine the extent to which particle induced X-ray emission (PIXE) could be applied in the lateral diffusion couple study of a system with relatively close atomic numbers. This was with a view that it may eventually be adopted to study systems where the atomic numbers are too close for RBS analysis. The system studied here was the Ni-Ge binary system. Since RBS is an established technique for studying lateral diffusion couples, we used it as a standard for comparison. The PIXE results showed a maximum error of 12% with reference to the RBS standard. In order to achieve the most effective use of PIXE in lateral diffusion couple studies we recommend the use of the technique in such a way as to obtain depth information and the use of relatively thick sample layers.
Moment coupling in the interaction of atoms and their ions with a 3d-electron shell
Kosarim, A. V.; Smirnov, B. M.; Capitelli, M.; Laricchiuta, A.
2011-09-15
The moment coupling of an interacting ion and an atom with a 3d-electron shell is analyzed for the ground state of identical atoms and ions where resonant charge exchange proceeds with transition of a 4s-electron. The interaction of the ion charge with the atom quadrupole moment is important for this system along with the exchange interactions and spin-orbit interactions inside an isolated atom and an ion. The quadrupole moment for 3d-atoms in the ground states is evaluated. The hierarchy of interactions in a molecular ion is analyzed depending on ion-atom distances and is compared with the standard Hund scheme. The resonant charge exchange proceeds effectively at separations corresponding to an intermediate case between cases 'a' and 'c' of the Hund coupling scheme.
NASA Technical Reports Server (NTRS)
Schreiber, Henry D.; Merkel, Robert C., Jr.; Schreiber, V. Lea; Balazs, G. Bryan
1987-01-01
The mutual interactions via electron exchange of redox couples in glass-forming melts were investigated both theoretically and experimentally. A thermodynamic approach for considering the mutual interactions leads to conclusion that the degree of mutual interaction in the melt should be proportional in part to the difference in relative reduction potentials of the interacting redox couples. Experimental studies verify this conclusion for numerous redox couples in several composition/temperature/oxygen fugacity regimes. Geochemical systems simultaneously possess many potentially multivalent elements; the stabilized redox states in the resulting magmas can be explained in part by mutual interactions and by redox buffering through the central Fe(III)- Fe(II) couples in the melts. The significance of these results for basaltic magmas of the earth, moon, and meteorites is addressed.
Ab Initio Coupled-Cluster Approach to Nuclear Structure with Modern Nucleon-Nucleon Interactions
Hagen, Gaute; Papenbrock, T.; Dean, David Jarvis; Hjorth-Jensen, M.
2010-01-01
We perform coupled-cluster calculations for the doubly magic nuclei ^{4}He, ^{16}O, and ^{40,48}Ca for neutron-rich isotopes of oxygen and fluorine, and employ "bare" and secondary renormalized nucleon-nucleon interactions. For the nucleon-nucleon interaction from chiral effective field theory at order next-to-next-to-next-to leading order, we find that the coupled-cluster approximation including triples corrections binds nuclei within 0.4 MeV per nucleon compared to data. We employ interactions from a resolution-scale dependent similarity renormalization group transformation and assess the validity of power-counting estimates in medium-mass nuclei. We find that the missing contributions due to three-nucleon forces are consistent with these estimates. For the unitary correlator model potential, we find a slow convergence with respect to increasing the size of the model space. For the G-matrix approach, we find a weak dependence of ground-state energies on the starting energy combined with a rather slow convergence with respect to increasing model spaces. We also analyze the center-of-mass problem and present a practical and efficient solution.
Multi-disciplinary coupling effects for integrated design of propulsion systems
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Singhal, S. N.
1993-01-01
Effective computational simulation procedures are described for modeling the inherent multi-disciplinary interactions which govern the accurate response of propulsion systems. Results are presented for propulsion system responses including multi-disciplinary coupling effects using coupled multi-discipline thermal, structural, and acoustic tailoring; an integrated system of multi-disciplinary simulators; coupled material behavior/fabrication process tailoring; sensitivities using a probabilistic simulator; and coupled materials, structures, fracture, and probabilistic behavior simulator. The results demonstrate that superior designs can be achieved if the analysis/tailoring methods account for the multi-disciplinary coupling effects. The coupling across disciplines can be used to develop an integrated coupled multi-discipline numerical propulsion system simulator.
NASA Astrophysics Data System (ADS)
Bi, Siwei; Liu, Chengbu; Hu, Haiquan; Zhang, Changqiao
2001-12-01
The magnetic coupling interaction for Cu(II) binuclear systems with bridging groups C2O4 2- , C2O2( NH) 2 2- ( cis), C2O2( NH) 2 2- ( trans) and C2S2( NH) 2 2- ( trans) was studied by the broken symmetry (BS) approach within the framework of the density functional theory (DFT). The influence of different coordination atoms and geometry on magnetic coupling interaction was theoretically analyzed. Both of the calculated and experimental results were compared. The variation trends of coupling interaction calculated are in agreement with experimental ones.
Comparing Effects of Cluster-Coupled Patterns on Opinion Dynamics
NASA Astrophysics Data System (ADS)
Liu, Yun; Si, Xia-Meng; Zhang, Yan-Chao
2012-07-01
Community structure is another important feature besides small-world and scale-free property of complex networks. Communities can be coupled through specific fixed links between nodes, or occasional encounter behavior. We introduce a model for opinion evolution with multiple cluster-coupled patterns, in which the interconnectivity denotes the coupled degree of communities by fixed links, and encounter frequency controls the coupled degree of communities by encounter behaviors. Considering the complicated cognitive system of people, the CODA (continuous opinions and discrete actions) update rules are used to mimic how people update their decisions after interacting with someone. It is shown that, large interconnectivity and encounter frequency both can promote consensus, reduce competition between communities and propagate some opinion successfully across the whole population. Encounter frequency is better than interconnectivity at facilitating the consensus of decisions. When the degree of social cohesion is same, small interconnectivity has better effects on lessening the competence between communities than small encounter frequency does, while large encounter frequency can make the greater degree of agreement across the whole populations than large interconnectivity can.
NASA Astrophysics Data System (ADS)
Gentine, P.; Lintner, B. R.; Findell, K. L.; Rochetin, N.; Sobel, A. H.; Anber, U. M.
2014-12-01
We will present two idealized epxeriments/methodologies to investigate local (LoCo) and large-scale (LsCo) coupling between the surface and the atmsophere: the contiental Radiative-Convective Equilibrium (RCE) and the continental Weak Temperature Gradient (WTG). The RCE defines an equilibrium state of coupling between the surafce and the atmosphere isolated from any large-scale dependence, which were investigated within the single column model of the Laboratoire de Meteorologie Dynamique (LMD) coupled to a simple bucket land model. This studies emphasizes the role of low-level cloud and the diurnal cylce of the boundary layer on the final state of the system. In the WTG we investigate the coupling between the surface and the atmosphere during the dry and wet season of the Amazon with the WRF model coupled to the NOAH land-surface model. Large-scale coupling is obtained with the WTG. The dry and wet season demonstrate very fundamental behavior: in the dry season deep convection is generated by radiative cooling in the higher troposhere and is disconnected from the surface. In the wet season the coupling between the surface and the atmosphere is much tighter. We suggest that the WTG is a powerful tool to investigate the coupling between the surface and the atmosphere, which solves two major issues: the limited resolution of convection in GCMs and the lack of large-scale coupling in CRM. Later investigation will look at the effect of deforestation, water table and distance from the ocean.
Coupling Ecology and River Dynamics using a Simplified Interaction Model
NASA Astrophysics Data System (ADS)
Longjas, A.; Czuba, J. A.; Schwenk, J.; Danesh Yazdi, M.; Hansen, A.; Foufoula-Georgiou, E.
2013-12-01
Quantifying how changes in streamflow and sediment affect riverine life is an important component of river basin management and stream restoration efforts, especially under human and climate-induced changes affecting many basins around the world. In the Midwestern US, drastic changes in mussel populations have been witnessed over the past decade begging quantitative understanding of cause and effect and attribution of these changes to the concurrent changes in streamflow and sediment loads to the rivers. Previous empirical analyses have attempted to explore mussel abundance with habitat associations and bulk hydrologic and geomorphic attributes as predictors but results showed relatively weak relationships and low predictive power. In this work, we developed a process-based model that incorporates water-sediment-mussel interactions using functional relationships and predicts the long-term trends of suspended-sediment, chlorophyll-a and mussel population using a daily streamflow record. We applied the model to the Minnesota River Basin, which has experienced significant changes in precipitation and runoff, increased sediment delivery, and decreasing mussel populations. Our model captures the general dynamics of the system and provides a better predictor of mussel populations than predictions based on geomorphic (e.g. upstream drainage area, slope) and hydraulic variables (e.g. 2-year recurrence interval peak streamflow, depth, width, cross sectional area, velocity, and Froude number) alone. To highlight the utility of our model, we tested possible scenarios that illustrate (1) how climate and land-use change may undermine the resilience of mussel populations and (2) how management efforts can allow mussel populations to recover.
Time Delay Effect in a Living Coupled Oscillator System with the Plasmodium of Physarum polycephalum
NASA Astrophysics Data System (ADS)
Takamatsu, Atsuko; Fujii, Teruo; Endo, Isao
2000-08-01
A living coupled oscillator system was constructed by a cell patterning method with a plasmodial slime mold, in which parameters such as coupling strength and distance between the oscillators can be systematically controlled. Rich oscillation phenomena between the two-coupled oscillators, namely, desynchronizing and antiphase/in-phase synchronization were observed according to these parameters. Both experimental and theoretical approaches showed that these phenomena are closely related to the time delay effect in interactions between the oscillators.
Coupling GSM/ALE with ES-FEM-T3 for fluid-deformable structure interactions
NASA Astrophysics Data System (ADS)
Wang, S.; Khoo, B. C.; Liu, G. R.; Xu, G. X.; Chen, L.
2014-11-01
In light of the effectiveness of the edge-based smoothed finite element method (ES-FEM-T3) and arbitrary Lagrangian-Eulerian gradient smoothing method (GSM/ALE) in, respectively, solving the pure solid and fluid flow problems using three-node triangular elements, they are coupled together in the present study to solve the more challenging fluid-deformable structure interaction (FSI) problems based on the weak coupling algorithm. Specifically, the fluid flow is tracked over the moving mesh with the well developed GSM/ALE and the transient response of the solid part is solved by the newly developed explicit ES-FEM-T3. The solutions from these two parts are “linked” together by the carefully formulated FSI coupling conditions on the FSI interface. Detailed procedures are summarized to illustrate the implementations of the GSM/ALE with ES-FEM-T3 in an FSI analysis. Three benchmarks are employed to validate the proposed coupled smoothed method in solving both transient and steady-state FSI problems. The mesh sensitivity analysis is further carried out showing that the results of an FSI system appear more sensitive to the change in the solid mesh as compared to the fluid mesh, thus suggesting a more refined mesh for the solid part. Another significant finding is that the present method can still produce reliable results even on the extremely distorted mesh near the FSI interface. The successful coupling GSM/ALE with ES-FEM-T3 for solving FSI problems serves as a good start for further implementing the family of smoothed methods in solving more complex cross-area problems.
ERIC Educational Resources Information Center
Welsh, Deborah P.; Vickerman, Renee; Rostosky, Sherry S.; Kawaguchi, Myra C.
Researchers have largely neglected adolescents' romantic relationships. To help fill this research gap, some of the discrepancies between adolescent couples' and observers' perceptions of couples' conversations are examined here. Two approaches to interaction analysis were used: the divergent realities paradigm, which explores divergences in…
Do the Naive Know Best? The Predictive Power of Naive Ratings of Couple Interactions
ERIC Educational Resources Information Center
Baucom, Katherine J. W.; Baucom, Brian R.; Christensen, Andrew
2012-01-01
We examined the utility of naive ratings of communication patterns and relationship quality in a large sample of distressed couples. Untrained raters assessed 10-min videotaped interactions from 134 distressed couples who participated in both problem-solving and social support discussions at each of 3 time points (pre-therapy, post-therapy, and…
Strong interactive massive particles from a strong coupled theory
Khlopov, Maxim Yu.; Kouvaris, Chris
2008-03-15
Minimal walking technicolor models can provide a nontrivial solution for cosmological dark matter, if the lightest technibaryon is doubly charged. Technibaryon asymmetry generated in the early Universe is related to baryon asymmetry, and it is possible to create an excess of techniparticles with charge (-2). These excessive techniparticles are all captured by {sup 4}He, creating techni-O-helium tOHe atoms, as soon as {sup 4}He is formed in big bang nucleosynthesis. The interaction of techni-O-helium with nuclei opens new paths to the creation of heavy nuclei in big bang nucleosynthesis. Because of the large mass of technibaryons, the tOHe ''atomic'' gas decouples from the baryonic matter and plays the role of dark matter in large scale structure formation, while structures in small scales are suppressed. Nuclear interactions with matter slow down cosmic techni-O-helium in the Earth below the threshold of underground dark matter detectors, thus escaping severe cryogenic dark matter search constraints. On the other hand, these nuclear interactions are not sufficiently strong to exclude this form of strongly interactive massive particles by constraints from the XQC experiment. Experimental tests of this hypothesis are possible in the search for tOHe in balloon-borne experiments (or on the ground) and for its charged techniparticle constituents in cosmic rays and accelerators. The tOHe atoms can cause cold nuclear transformations in matter and might form anomalous isotopes, offering possible ways to exclude (or prove?) their existence.
Unified theory of effective interaction
NASA Astrophysics Data System (ADS)
Takayanagi, Kazuo
2016-09-01
We present a unified description of effective interaction theories in both algebraic and graphic representations. In our previous work, we have presented the Rayleigh-Schrödinger and Bloch perturbation theories in a unified fashion by introducing the main frame expansion of the effective interaction. In this work, we start also from the main frame expansion, and present various nonperturbative theories in a coherent manner, which include generalizations of the Brandow, Brillouin-Wigner, and Bloch-Horowitz theories on the formal side, and the extended Krenciglowa-Kuo and the extended Lee-Suzuki methods on the practical side. We thus establish a coherent and comprehensive description of both perturbative and nonperturbative theories on the basis of the main frame expansion.
Self-interacting asymmetric dark matter coupled to a light massive dark photon
Petraki, Kalliopi; Pearce, Lauren; Kusenko, Alexander E-mail: lpearce@ucla.edu
2014-07-01
Dark matter (DM) with sizeable self-interactions mediated by a light species offers a compelling explanation of the observed galactic substructure; furthermore, the direct coupling between DM and a light particle contributes to the DM annihilation in the early universe. If the DM abundance is due to a dark particle-antiparticle asymmetry, the DM annihilation cross-section can be arbitrarily large, and the coupling of DM to the light species can be significant. We consider the case of asymmetric DM interacting via a light (but not necessarily massless) Abelian gauge vector boson, a dark photon. In the massless dark photon limit, gauge invariance mandates that DM be multicomponent, consisting of positive and negative dark ions of different species which partially bind in neutral dark atoms. We argue that a similar conclusion holds for light dark photons; in particular, we establish that the multi-component and atomic character of DM persists in much of the parameter space where the dark photon is sufficiently light to mediate sizeable DM self-interactions. We discuss the cosmological sequence of events in this scenario, including the dark asymmetry generation, the freeze-out of annihilations, the dark recombination and the phase transition which gives mass to the dark photon. We estimate the effect of self-interactions in DM haloes, taking into account this cosmological history. We place constraints based on the observed ellipticity of large haloes, and identify the regimes where DM self-scattering can affect the dynamics of smaller haloes, bringing theory in better agreement with observations. Moreover, we estimate the cosmological abundance of dark photons in various regimes, and derive pertinent bounds.
NASA Astrophysics Data System (ADS)
Gupta, Arvind Kumar
2016-03-01
Motivated by the recent experimental observations on clustering of motor proteins on microtubule filament, we study an open system of two parallel totally asymmetric simple exclusion processes under asymmetric coupling conditions, which incorporates the mutual interaction with the surrounding environment through Langmuir Kinetics (LK) in both the lanes. In the modified LK, the attachment and detachment rates depends on the configuration of nearest neighboring sites. We analyse the model within the framework of continuum mean-field theory and the phase diagrams along with density profiles are obtained using boundary layer analysis. The effect of mutual interactions on the phase diagram for two different situations of attachment and detachment (LK) rates is discussed. Under the symmetric LK dynamics, the topological structure of the phase diagram remains similar to the one in without mutual interaction; while for the antisymmetric case, after a certain critical value of attractive/repulsive mutual attraction, significant changes are found in the qualitative nature of phase diagram. Moreover, it is shown that the type of mutual interaction affects the dynamic properties of motor proteins. The theoretical findings are examined by extensive Monte-Carlo simulations.
NASA Astrophysics Data System (ADS)
Huo, Dong-Ming
2016-07-01
Using the Green's function technique, we respectively investigate the electron transport properties of two spin components through the system of a T-shaped double quantum dot structure coupled to a Majorana bound state, in which only one quantum dot is connected with two metallic leads. We explore the interplay between the Fano effect and the MBSs for different dot-MBS coupling strength λ, dot-dot coupling strength t, and MBS-MBS coupling strength ɛM in the noninteracting case. Then the Coulomb interaction and magnetic field effect on the conductance spectra are investigated. Our results indicate that G↓(ω) is not affected by the Majorana bound states, but a "0.5" conductance signature occurs in the vicinities of Fermi level of G↑(ω). This robust property persists for a wide range of dot-dot coupling strength and dot-MBS coupling strength, but it can be destroyed by Coulomb interaction in quantum dots. By adjusting the size and direction of magnetic field around the quantum dots, the "0.5" conductance signature damaged by U can be restored. At last, the spin magnetic moments of two dots by applying external magnetic field are also predicted.
Effective interactions between fluid membranes
NASA Astrophysics Data System (ADS)
Lu, Bing-Sui; Podgornik, Rudolf
2015-08-01
A self-consistent theory is proposed for the general problem of interacting undulating fluid membranes subject to the constraint that they do not interpenetrate. We implement the steric constraint via an exact functional integral representation and, through the use of a saddle-point approximation, transform it into a novel effective steric potential. The steric potential is found to consist of two contributions: one generated by zero-mode fluctuations of the membranes and the other by thermal bending fluctuations. For membranes of cross-sectional area S , we find that the bending fluctuation part scales with the intermembrane separation d as d-2 for d ≪√{S } but crosses over to d-4 scaling for d ≫√{S } , whereas the zero-mode part of the steric potential always scales as d-2. For membranes interacting exclusively via the steric potential, we obtain closed-form expressions for the effective interaction potential and for the rms undulation amplitude σ , which becomes small at low temperatures T and/or large bending stiffnesses κ . Moreover, σ scales as d for d ≪√{S } but saturates at √{kBT S /κ } for d ≫√{S } . In addition, using variational Gaussian theory, we apply our self-consistent treatment to study intermembrane interactions subject to different types of potentials: (i) the Moreira-Netz potential for a pair of strongly charged membranes with an intervening solution of multivalent counterions, (ii) an attractive square well, (iii) the Morse potential, and (iv) a combination of hydration and van der Waals interactions.
Effective interactions between fluid membranes.
Lu, Bing-Sui; Podgornik, Rudolf
2015-08-01
A self-consistent theory is proposed for the general problem of interacting undulating fluid membranes subject to the constraint that they do not interpenetrate. We implement the steric constraint via an exact functional integral representation and, through the use of a saddle-point approximation, transform it into a novel effective steric potential. The steric potential is found to consist of two contributions: one generated by zero-mode fluctuations of the membranes and the other by thermal bending fluctuations. For membranes of cross-sectional area S, we find that the bending fluctuation part scales with the intermembrane separation d as d-2 for d≪√S but crosses over to d-4 scaling for d≫√S, whereas the zero-mode part of the steric potential always scales as d-2. For membranes interacting exclusively via the steric potential, we obtain closed-form expressions for the effective interaction potential and for the rms undulation amplitude σ, which becomes small at low temperatures T and/or large bending stiffnesses κ. Moreover, σ scales as d for d≪√S but saturates at √kBTS/κ for d≫√S. In addition, using variational Gaussian theory, we apply our self-consistent treatment to study intermembrane interactions subject to different types of potentials: (i) the Moreira-Netz potential for a pair of strongly charged membranes with an intervening solution of multivalent counterions, (ii) an attractive square well, (iii) the Morse potential, and (iv) a combination of hydration and van der Waals interactions. PMID:26382349
Modelling Tropical Cyclones-Ocean interactions: the role of the Atmophere - Ocean coupling frequency
NASA Astrophysics Data System (ADS)
Scoccimarro, Enrico; Fogli, Pier Giuseppe; Gualdi, Silvio; Masina, Simona; Navarra, Antonio
2016-04-01
The interaction between Tropical Cyclones (TCs) and ocean is a major mechanism responsible for energy exchange between the atmosphere and the ocean. TCs affect the thermal and dynamical structure of the ocean, but the magnitude of the impact is still uncertain. Very few CMIP5 models demonstrated ability in representing TCs, mainly due to their horizontal resolution. We aim to improve TCs representation in next CMIPs experiments through the new CMCC-CM2VHR General Circulation Model, having a horizontal resolution of 1/4 degree in both atmospheric and ocean components. The model is capable to represent realistically TCs up to Cat-5 Typhoons. A good representation of the TC-Ocean interaction strongly depends on the coupling frequency between the atmospheric and the ocean components. In this work, we found that a better representation of the negative Sea Surface Temperature - TC induced feedback, through a high (hourly) coupling frequency, ensures the reduction of the TC induced Power Dissipation Index (PDI) bias of one order of magnitude. In addition, a cat-5 storm case study is deeply investigated also in terms of TC effects on the deep ocean.
NASA Astrophysics Data System (ADS)
Wang, Luo; Rui, Li; Zhiqiang, Gai; RuiBo, Ai; Hongmin, Zhang; Xiaomei, Zhang; Bing, Yan
2016-07-01
Lead oxide (PbO), which plays the key roles in a range of research fields, has received a great deal of attention. Owing to the large density of electronic states and heavy atom Pb including in PbO, the excited states of the molecule have not been well studied. In this work, high level multireference configuration interaction calculations on the low-lying states of PbO have been carried out by utilizing the relativistic effective core potential. The effects of the core-valence correlation correction, the Davidson modification, and the spin–orbital coupling on the electronic structure of the PbO molecule are estimated. The potential energy curves of 18 Λ-S states correlated to the lowest dissociation limit (Pb (3Pg) + O(3Pg)) are reported. The calculated spectroscopic parameters of the electronic states below 30000 cm‑1, for instance, X1Σ+, 13Σ+, and 13Σ‑, and their spin–orbit coupling interaction, are compared with the experimental results, and good agreements are derived. The dipole moments of the 18 Λ-S states are computed with the configuration interaction method, and the calculated dipole moments of X1Σ+ and 13Σ+ are consistent with the previous experimental results. The transition dipole moments from 11Π, 21Π, and 21Σ+ to X1Σ+ and other singlet excited states are estimated. The radiative lifetime of several low-lying vibrational levels of 11Π, 21Π, and 21Σ+ states are evaluated. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404180 and 11574114), the Natural Science Foundation of Heilongjiang Province, China (Grant No. A2015010), the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province, China (Grant No. UNPYSCT-2015095), and the Natural Science Foundation of Jilin Province, China (Grant No. 20150101003JC).
Semantic Interaction for Visual Analytics: Toward Coupling Cognition and Computation
Endert, Alexander
2014-07-01
The dissertation discussed in this article [1] was written in the midst of an era of digitization. The world is becoming increasingly instrumented with sensors, monitoring, and other methods for generating data describing social, physical, and natural phenomena. Thus, data exist with the potential of being analyzed to uncover, or discover, the phenomena from which it was created. However, as the analytic models leveraged to analyze these data continue to increase in complexity and computational capability, how can visualizations and user interaction methodologies adapt and evolve to continue to foster discovery and sensemaking?
A coupled hidden Markov model for disease interactions.
Sherlock, Chris; Xifara, Tatiana; Telfer, Sandra; Begon, Mike
2013-08-01
To investigate interactions between parasite species in a host, a population of field voles was studied longitudinally, with presence or absence of six different parasites measured repeatedly. Although trapping sessions were regular, a different set of voles was caught at each session, leading to incomplete profiles for all subjects. We use a discrete time hidden Markov model for each disease with transition probabilities dependent on covariates via a set of logistic regressions. For each disease the hidden states for each of the other diseases at a given time point form part of the covariate set for the Markov transition probabilities from that time point. This allows us to gauge the influence of each parasite species on the transition probabilities for each of the other parasite species. Inference is performed via a Gibbs sampler, which cycles through each of the diseases, first using an adaptive Metropolis-Hastings step to sample from the conditional posterior of the covariate parameters for that particular disease given the hidden states for all other diseases and then sampling from the hidden states for that disease given the parameters. We find evidence for interactions between several pairs of parasites and of an acquired immune response for two of the parasites. PMID:24223436
Simulating coupled thermal-mechanical interactions in morphing radiators
NASA Astrophysics Data System (ADS)
Bertagne, Christopher L.; Sheth, Rubik B.; Hartl, Darren J.; Whitcomb, John D.
2015-04-01
Thermal control is an important aspect of every spacecraft. The thermal control system (TCS) must maintain the temperature of all other systems within acceptable limits in spite of changes in environmental conditions or heat loads. Most thermal control systems used in crewed vehicles use a two-fluid-loop architecture in order to achieve the flexibility demanded by the mission. The two-loop architecture provides sufficient performance, but it does so at the cost of additional mass. A recently-proposed radiator concept known as a morphing radiator employs shape memory alloys in order to achieve the performance necessary to use a single-loop TCS architecture. However, modeling the behavior of morphing radiators is challenging due to the presence of a unique and complex thermomechanical coupling. In this work, a partitioned analysis procedure is implemented with existing finite element solvers in order to explore the behavior of a possible shape memory alloy-based morphing radiator in a mission-like thermal environment. The results help confirm the theory of operation and demonstrate the ability of this method to support the design and development of future morphing radiators.
Diamond, Lisa M; Hicks, Angela M; Otter-Henderson, Kimberly D
2011-06-01
Previous research suggests that cardiac vagal regulation (indexed by respiratory sinus arrhythmia, or RSA) provides a physiological substrate for affect regulation, which presumably underlies adaptive interpersonal functioning.The authors tested these associations in the context of daily interactions between 68 cohabiting couples. Participants underwent a laboratory assessment of RSA during rest and also during a series of psychological stressors. Subsequently, they kept daily measures of affect and interaction quality for 21 days. Individual differences in baseline and stress levels of RSA moderated within-person associations between daily affect and the quality of couple interactions. The pattern of results differed for women versus men. Men with lower vagal tone or higher vagal reactivity had stronger associations between daily negative affect and daily negative interactions, and men with higher vagal tone had more positive daily interactions overall. Women with higher vagal tone had stronger associations between daily positive affect and daily positive interactions. PMID:21393615
NASA Astrophysics Data System (ADS)
Sun, Kuei; Qu, Chunlei; Xu, Yong; Zhang, Yongping; Zhang, Chuanwei
Spin-orbit (SO) coupling plays a major role in many important phenomena in condensed matter physics. However, the SO coupling physics in high-spin systems, especially with superfluids, has not been well explored because of the spin half of electrons in solids. In this context, the recent experimental realization of spin-orbit coupling in spin-1 Bose-Einstein condensates (BECs) has opened a completely new avenue for exploring SO-coupled high-spin superfluids. Nevertheless, the experiment has only revealed the single-particle physics of the system. Here, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 BECs in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting two modulating patterns. We characterize the phase transitions between different phases using the spin-tensor density as well as the collective dipole motion of the BEC. We show that there exists a new type of double maxon-roton structure in the Bogoliubov-excitation spectrum, attributing to the three band minima of the SO-coupled spin-1 BEC. Our work could motivate further theoretical and experimental study along this direction.
Resonant atom-field interaction in large-size coupled-cavity arrays
Ciccarello, Francesco
2011-04-15
We consider an array of coupled cavities with staggered intercavity couplings, where each cavity mode interacts with an atom. In contrast to large-size arrays with uniform hopping rates where the atomic dynamics is known to be frozen in the strong-hopping regime, we show that resonant atom-field dynamics with significant energy exchange can occur in the case of staggered hopping rates even in the thermodynamic limit. This effect arises from the joint emergence of an energy gap in the free photonic dispersion relation and a discrete frequency at the gap's center. The latter corresponds to a bound normal mode stemming solely from the finiteness of the array length. Depending on which cavity is excited, either the atomic dynamics is frozen or a Jaynes-Cummings-like energy exchange is triggered between the bound photonic mode and its atomic analog. As these phenomena are effective with any number of cavities, they are prone to be experimentally observed even in small-size arrays.
Spin-orbit coupling in the strongly interacting Fermi gas: an exact quantum Monte Carlo study
NASA Astrophysics Data System (ADS)
Rosenberg, Peter; Shi, Hao; Chiesa, Simone; Zhang, Shiwei
Spin-orbit coupling (SOC) plays an essential role in a variety of intriguing condensed matter phenomena, including the quantum Hall effect, and topological insulators and superconductors. The recent experimental realization of spin-orbit coupled Fermi gases provides a unique opportunity to study the effects of SOC in a tunable, disorder-free system. Motivated by this experimental progress, we present here the first exact numerical results on the two-dimensional, unpolarized, uniform Fermi gas with attractive interactions and Rashba SOC. Using auxiliary-field quantum Monte Carlo and incorporating recent algorithmic advances, we carry out exact calculations on sufficiently large system sizes to provide accurate results systematically as a function of experimental parameters. We obtain the equation of state, study the spin behavior and momentum distribution, and examine the interplay of SOC and pairing in real and momentum space. Our results help illuminate the rich pairing structure induced by SOC, and provide important guidance to future experimental efforts. Supported by DOE SciDAC and NSF.
Experimental determination of the effective strong coupling constant
Alexandre Deur; Volker Burkert; Jian-Ping Chen; Wolfgang Korsch
2005-09-15
We extract an effective strong coupling constant from low Q2 data on the Bjorken sum. Using sum rules, we establish its Q2-behavior over the complete Q2-range. The result is compared to effective coupling constants extracted from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constant and the calculations is not clear, the results agree surprisingly well.
NASA Astrophysics Data System (ADS)
Murakami, Yuta; Werner, Philipp; Tsuji, Naoto; Aoki, Hideo
2013-09-01
We study the Holstein-Hubbard model at half filling to explore ordered phases including superconductivity (SC), antiferromagnetism (AF), and charge order (CO) in situations where the electron-electron and electron-phonon interactions are strong (comparable to the electronic bandwidth). The model is solved in the dynamical mean-field approximation with a continuous-time quantum Monte Carlo impurity solver. We determine the superconducting transition temperature Tc and the SC order parameter and show that the phonon-induced retardation or the strong Coulomb interaction leads to a significant reduction and shift of the Tc dome against the effective electron-electron interaction Ueff given by the Hubbard U reduced by the phonon-mediated attraction in the static limit. This behavior is analyzed by comparison to an effective static model in the polaron representation with a renormalized bandwidth. In addition, we discuss the superconducting gap Δ and 2Δ/Tc to reveal the effect of the retardation and the Coulomb interaction. We also determine the finite-temperature phase diagram including AF and CO. In the moderate-coupling regime, there is a hysteretic region of AF and CO around Ueff=0, while the two phases are separated by a paramagnetic metal in the weak-coupling regime and a paramagnetic insulator in the strong-coupling regime.
Ellis, Benjamin H; Aggarwal, Somil; Chakraborty, Arindam
2016-01-12
Multicomponent systems are defined as chemical systems that require a quantum mechanical description of two or more different types of particles. Non-Born-Oppenheimer electron-nuclear interactions in molecules, electron-hole interactions in electronically excited nanoparticles, and electron-positron interactions are examples of physical systems that require a multicomponent quantum mechanical formalism. The central challenge in the theoretical treatment of multicomponent systems is capturing the many-body correlation effects that exist not only between particles of identical types (electron-electron) but also between particles of different types (electron-nuclear and electron-hole). In this work, the development and implementation of multicomponent coupled-cluster (mcCC) theory for treating particle-particle correlation in multicomponent systems are presented. This method provides a balanced treatment of many-particle correlation effects in a general multicomponent system while maintaining a size-consistent and size-extensive formalism. The coupled-cluster ansatz presented here is an extension of the electronic structure CCSD formulation for multicomponent systems and is defined as |ΨmcCC⟩ = eT1I+T2I+T1II+T2II+T11I,II+T12I,II+T21I,II+T22I,II|0I0II⟩. The cluster amplitudes in the mcCC wave function were obtained by projecting the mcCC Schrödinger equation onto a direct product space of singly and doubly excited states of type I and II particles and then solving the resulting mcCC equations iteratively. These equations were derived using an automated application of the generalized Wick’s theorem and were implemented using a computer-assisted source code generation approach. The applicability of the mcCC method was demonstrated by calculating ground state energies of multicomponent Hooke's atom and positronium hydride systems as well as by calculating exciton and biexciton binding energies in multiexcitonic systems. For each case, the mcCC results were
Topics in HPM (High-Power Microwave) generation, coupling, and interaction
NASA Astrophysics Data System (ADS)
Casey, Kendall F.
1990-01-01
A collection is presented of technical notes on various aspects of high power microwave (HPM) generation, coupling, and interaction. Time and resources did not permit either as detailed an editing job would have been desirable, or recalculation and plotting of the numerical results in a more elegant form. It is to be hoped, however, that this integrated document will prove useful to the community. The selection of topics addressed in the Microwave Notes was influenced by questions which arose at various stages of the author's involvement in HPM-related activities. The subject of pulse radiation from aperture antennas subject to turn-on time errors, for example, arose in the context of a proposed HPM generation scheme. Consideration of the scattering cross-section of a simple dipole and of its dual problem, the effective area of a thin slot, was motivated by the need to understand the penetration of such slot apertures by HPM pulses.
Quantum dissipative effect of one dimension coupled anharmonic oscillator
Sulaiman, A.; Zen, Freddy P.
2015-04-16
Quantum dissipative effect of one dimension coupled anharmonic oscillator is investigated. The systems are two coupled harmonic oscillator with the different masses. The dissipative effect is studied based on the quantum state diffusion formalism. The result show that the anharmonic effect increase the amplitude but the lifetime of the oscillation depend on the damping coefficient and do not depend on the temperature.
Effective Student Learning of Fractions with an Interactive Simulation
ERIC Educational Resources Information Center
Hensberry, Karina K. R.; Moore, Emily B.; Perkins, Katherine K.
2015-01-01
Computer technology, when coupled with reform-based teaching practices, has been shown to be an effective way to support student learning of mathematics. The quality of the technology itself, as well as how it is used, impacts how much students learn. Interactive simulations are dynamic virtual environments similar to virtual manipulatives that…
Laser-material interactions: A study of laser energy coupling with solids
Shannon, M A
1993-11-01
This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heating of opaque solids that have not undergone phase-change. Of main interest is the physical significance of the shape, magnitude, and phase for the temporal profile of the deflection signal. Considered are the effects that thermophysical properties, boundary conditions, and geometry of the target and optical probe-beam have on the deflection response. PTD is shown to monitor spatial and temporal changes in heat flux leaving the surface due to changes in laser energy coupling. The PTD technique is then extended to detect phase-change at the surface of a solid target. Experimental data shows the onset of melt for indium and tin targets. The conditions for which melt can be detected by PTD is analyzed in terms of geometry, incident power and pulse length, and thermophysical properties of the target and surroundings. Next, monitoring high-powered laser ablation of materials with stress-power is introduced. The motivation for considering stress-power is given, followed by a theoretical discussion of stress-power and how it is determined experimentally. Experiments are presented for the ablation of aluminum targets as a function of energy and intensity. The stress-power response is analyzed for its physical significance. Lastly, the influence of plasma-shielding during high-powered pulsed laser-material interactions is considered. Crater size, emission, and stress-power are measured to determine the role that the gas medium and laser pulse length have on plasma shielding.
NASA Technical Reports Server (NTRS)
Mei, Chuh; Pates, Carl S., III
1994-01-01
A coupled boundary element (BEM)-finite element (FEM) approach is presented to accurately model structure-acoustic interaction systems. The boundary element method is first applied to interior, two and three-dimensional acoustic domains with complex geometry configurations. Boundary element results are very accurate when compared with limited exact solutions. Structure-interaction problems are then analyzed with the coupled FEM-BEM method, where the finite element method models the structure and the boundary element method models the interior acoustic domain. The coupled analysis is compared with exact and experimental results for a simplistic model. Composite panels are analyzed and compared with isotropic results. The coupled method is then extended for random excitation. Random excitation results are compared with uncoupled results for isotropic and composite panels.
Mirroring and beyond: coupled dynamics as a generalized framework for modelling social interactions
Hasson, Uri; Frith, Chris D.
2016-01-01
When people observe one another, behavioural alignment can be detected at many levels, from the physical to the mental. Likewise, when people process the same highly complex stimulus sequences, such as films and stories, alignment is detected in the elicited brain activity. In early sensory areas, shared neural patterns are coupled to the low-level properties of the stimulus (shape, motion, volume, etc.), while in high-order brain areas, shared neural patterns are coupled to high-levels aspects of the stimulus, such as meaning. Successful social interactions require such alignments (both behavioural and neural), as communication cannot occur without shared understanding. However, we need to go beyond simple, symmetric (mirror) alignment once we start interacting. Interactions are dynamic processes, which involve continuous mutual adaptation, development of complementary behaviour and division of labour such as leader–follower roles. Here, we argue that interacting individuals are dynamically coupled rather than simply aligned. This broader framework for understanding interactions can encompass both processes by which behaviour and brain activity mirror each other (neural alignment), and situations in which behaviour and brain activity in one participant are coupled (but not mirrored) to the dynamics in the other participant. To apply these more sophisticated accounts of social interactions to the study of the underlying neural processes we need to develop new experimental paradigms and novel methods of data analysis PMID:27069044
Mirroring and beyond: coupled dynamics as a generalized framework for modelling social interactions.
Hasson, Uri; Frith, Chris D
2016-05-01
When people observe one another, behavioural alignment can be detected at many levels, from the physical to the mental. Likewise, when people process the same highly complex stimulus sequences, such as films and stories, alignment is detected in the elicited brain activity. In early sensory areas, shared neural patterns are coupled to the low-level properties of the stimulus (shape, motion, volume, etc.), while in high-order brain areas, shared neural patterns are coupled to high-levels aspects of the stimulus, such as meaning. Successful social interactions require such alignments (both behavioural and neural), as communication cannot occur without shared understanding. However, we need to go beyond simple, symmetric (mirror) alignment once we start interacting. Interactions are dynamic processes, which involve continuous mutual adaptation, development of complementary behaviour and division of labour such as leader-follower roles. Here, we argue that interacting individuals are dynamically coupled rather than simply aligned. This broader framework for understanding interactions can encompass both processes by which behaviour and brain activity mirror each other (neural alignment), and situations in which behaviour and brain activity in one participant are coupled (but not mirrored) to the dynamics in the other participant. To apply these more sophisticated accounts of social interactions to the study of the underlying neural processes we need to develop new experimental paradigms and novel methods of data analysis. PMID:27069044
Global fits of the dark matter-nucleon effective interactions
Catena, Riccardo; Gondolo, Paolo E-mail: paolo.gondolo@utah.edu
2014-09-01
The effective theory of isoscalar dark matter-nucleon interactions mediated by heavy spin-one or spin-zero particles depends on 10 coupling constants besides the dark matter particle mass. Here we compare this 11-dimensional effective theory to current observations in a comprehensive statistical analysis of several direct detection experiments, including the recent LUX, SuperCDMS and CDMSlite results. From a multidimensional scan with about 3 million likelihood evaluations, we extract the marginalized posterior probability density functions (a Bayesian approach) and the profile likelihoods (a frequentist approach), as well as the associated credible regions and confidence levels, for each coupling constant vs dark matter mass and for each pair of coupling constants. We compare the Bayesian and frequentist approach in the light of the currently limited amount of data. We find that current direct detection data contain sufficient information to simultaneously constrain not only the familiar spin-independent and spin-dependent interactions, but also the remaining velocity and momentum dependent couplings predicted by the dark matter-nucleon effective theory. For current experiments associated with a null result, we find strong correlations between some pairs of coupling constants. For experiments that claim a signal (i.e., CoGeNT and DAMA), we find that pairs of coupling constants produce degenerate results.
NASA Astrophysics Data System (ADS)
Yildirim, Taner
2009-05-01
We present a detailed first-principles study of Fe-pnictides with particular emphasis on competing magnetic interactions, structural phase transition, giant magneto-elastic coupling and its effect on phonons. The exchange interactions Ji, j( R) are calculated up to ≈12 Å from two different approaches based on direct spin-flip and infinitesimal spin-rotation. We find that Ji, j( R) has an oscillatory character with an envelop decaying as 1/ R3 along the stripe-direction while it is very short range along the diagonal direction and antiferromagnetic. A brief discussion of the neutron scattering determination of these exchange constants from a single crystal sample with orthorhombic-twinning is given. The lattice parameter dependence of the exchange constants, dJi, j/ da are calculated for a simple spin-Peierls like model to explain the fine details of the tetragonal-orthorhombic phase transition. We then discuss giant magneto-elastic effects in these systems. We show that when the Fe-spin is turned off the optimized c-values are shorter than experimental values by 1.4 Å for CaFe 2As 2, by 0.4 Å for BaFe 2As 2, and by 0.13 Å for LaOFeAs. We explain this strange behavior by unraveling surprisingly strong interactions between arsenic ions, the strength of which is controlled by the Fe-spin state through Fe-As hybridization. Reducing the Fe-magnetic moment, weakens the Fe-As bonding, and in turn, increases As-As interactions, causing a giant reduction in the c-axis. These findings also explain why the Fe-moment is so tightly coupled to the As-z position. Finally, we show that Fe-spin is also required to obtain the right phonon energies, in particular As c-polarized and Fe-Fe in-plane modes that have been recently observed by inelastic X-ray and neutron scattering but cannot be explained based on non-magnetic phonon calculations. Since treating iron as magnetic ion always gives much better results than non-magnetic ones and since there is no large c-axis reduction
Spin effects in the weak interaction
Freedman, S.J. Chicago Univ., IL . Dept. of Physics Chicago Univ., IL . Enrico Fermi Inst.)
1990-01-01
Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.
Response of different regional online coupled models to aerosol-radiation interactions
NASA Astrophysics Data System (ADS)
Forkel, Renate; Balzarini, Alessandra; Brunner, Dominik; Baró, Rocio; Curci, Gabriele; Hirtl, Marcus; Honzak, Luka; Jiménez-Guerrero, Pedro; Jorba, Oriol; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Schröder, Wolfram; Tuccella, Paolo; Werhahn, Johannes; Wolke, Ralf; Žabkar, Rahela
2016-04-01
The importance of aerosol-meteorology interactions and their representation in online coupled regional atmospheric chemistry-meteorology models was investigated in COST Action ES1004 (EuMetChem, http://eumetchem.info/). Case study results from different models (COSMO-Muscat, COSMO-ART, and different configurations of WRF-Chem), which were applied for Europe as a coordinated exercise for the year 2010, are analyzed with respect to inter-model variability and the response of the different models to direct and indirect aerosol-radiation interactions. The main focus was on two episodes - the Russian heat wave and wildfires episode in July/August 2010 and a period in October 2010 with enhanced cloud cover and rain and including an of Saharan dust transport to Europe. Looking at physical plausibility the decrease in downward solar radiation and daytime temperature due to the direct aerosol effect is robust for all model configurations. The same holds for the pronounced decrease in cloud water content and increase in solar radiation for cloudy conditions and very low aerosol concentrations that was found for WRF-Chem when aerosol cloud interactions were considered. However, when the differences were tested for statistical significance no significant differences in mean solar radiation and mean temperature between the baseline case and the simulations including the direct and indirect effect from simulated aerosol concentrations were found over Europe for the October episode. Also for the fire episode differences between mean temperature and radiation from the simulations with and without the direct aerosol effect were not significant for the major part of the modelling domain. Only for the region with high fire emissions in Russia, the differences in mean solar radiation and temperature due to the direct effect were found to be significant during the second half of the fire episode - however only for a significance level of 0.1. The few observational data indicate that
The Thirring interaction in the two-dimensional axial-current-pseudoscalar derivative coupling model
Belvedere, L.V. . E-mail: armflavio@if.uff.br
2006-12-15
We reexamine the two-dimensional model of massive fermions interacting with a massless pseudoscalar field via axial-current derivative coupling. The hidden Thirring interaction in the axial-derivative coupling model is exhibited compactly by performing a canonical field transformation on the Bose field algebra and the model is mapped into the Thirring model with an additional vector-current-scalar derivative interaction (Schroer-Thirring model). The Fermi field operator is rewritten in terms of the Mandelstam soliton operator coupled to a free massless scalar field. The charge sectors of the axial-derivative model are mapped into the charge sectors of the massive Thirring model. The complete bosonized version of the model is presented. The bosonized composite operators of the quantum Hamiltonian are obtained as the leading operators in the Wilson short distance expansions.
A state interaction spin-orbit coupling density matrix renormalization group method.
Sayfutyarova, Elvira R; Chan, Garnet Kin-Lic
2016-06-21
We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe2S2(SCH3)4](3-), determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter. PMID:27334156
A state interaction spin-orbit coupling density matrix renormalization group method
NASA Astrophysics Data System (ADS)
Sayfutyarova, Elvira R.; Chan, Garnet Kin-Lic
2016-06-01
We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe2S2(SCH3)4]3-, determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.
Investigating enhanced atmospheric-sea surface coupling and interactions in the Irish Sea
NASA Astrophysics Data System (ADS)
Maskell, John; Horsburgh, Kevin; Plater, Andy J.
2013-02-01
Enhanced atmospheric-sea surface coupling is investigated in the Irish Sea. The implications for so-called Proudman resonance are considered for a hindcast of an event that produced a significant, pressure-induced storm surge at the port of Liverpool. Time-series of non-dimensional gain along the depression track show resonant enhancement of the pressure-driven residual elevations in the central, deeper region of the Irish Sea when a depression moves at the speed of a shallow water wave (gh0.5). However, in the relatively shallow eastern Irish Sea the wind stress is the dominant surge-generating mechanism. Wind-generated surge magnitude is influenced by the propagation speed of the depression which controls the timing of momentum input with respect to tidal depth variations. Large surges at Liverpool are mostly caused by an almost linear summation of the wind- and pressure-induced surge components when the wind stress acts over low water and/or the rising tide. However, it is possible for the interaction of wind stress and pressure to reduce the total surge when a pressure-induced sea-level increase reduces the effect of the wind stress. The Irish Sea is too small for significant resonant enhancement due to atmospheric-sea surface coupling and surge magnitudes are strongly dependent on the intensity of the depression and the magnitude of the wind stress.
Laguna, Humberto G; Sagar, Robin P; Tempel, David G; Aspuru-Guzik, Alán
2016-01-01
The effects of bath coupling on an interacting two-particle quantum system are studied using tools from information theory. Shannon entropies of the one (reduced) and two-particle distribution functions in position, momentum and separable phase-space are examined. Results show that the presence of the bath leads to a delocalization of the distribution functions in position space, and a localization in momentum space. This can be interpreted as a loss of information in position space and a gain of information in momentum space. The entropy sum of the system, in the presence of a bath, is shown to be dependent on the strength of the interparticle potential and also on the strength of the coupling to the bath. The statistical correlation between the particles, and its dependence on the bath and interparticle potential, is examined using mutual information. A stronger repulsive potential between particles, in the presence of the bath, yields a smaller correlation between the particles positions, and a larger one between their momenta. PMID:26616490
Simulation of coupled sputter-diffusion effects
NASA Astrophysics Data System (ADS)
von Toussaint, U.; Mutzke, A.; Sugiyama, K.; Schwarz-Selinger, T.
2016-02-01
The simultaneous effects of sputtering, implantation and solid-state diffusion determine the surface profiles of mixed-material systems under ion-bombardment at elevated temperatures due to the enhanced atomic mobility. To simulate the joint processes the Monte Carlo code SDTrimSP for the simulation of the ion-solid interaction has been augmented by a diffusion model for solid-state diffusion. The combined model has been applied to a tungsten-iron system under deuterium bombardment as model system for EUROFER. The simulation results reveal a strong dependence of the surface profile on initial tungsten concentration, ion energy, temperature and fluence but also on the impinging flux, a parameter which is often not appropriately taken into account. For reactor relevant parameters of low-energy (200 eV) deuterium fluxes of {10}21{at} {{{m}}}-2 {{{s}}}-1 at 873 K a tungsten-iron system exhibits an increase of the tungsten surface concentration from initially 1% by a factor of more than 20, which drops at lower fluxes.
Spin-orbit coupled weakly interacting Bose-Einstein condensates in harmonic traps.
Hu, Hui; Ramachandhran, B; Pu, Han; Liu, Xia-Ji
2012-01-01
We investigate theoretically the phase diagram of a spin-orbit coupled Bose gas in two-dimensional harmonic traps. We show that at strong spin-orbit coupling the single-particle spectrum decomposes into different manifolds separated by ℏω{⊥}, where ω{⊥} is the trapping frequency. For a weakly interacting gas, quantum states with Skyrmion lattice patterns emerge spontaneously and preserve either parity symmetry or combined parity-time-reversal symmetry. These phases can be readily observed in a spin-orbit coupled gas of ^{87}Rb atoms in a highly oblate trap. PMID:22304247
Global constraints on vector-like WIMP effective interactions
Blennow, Mattias; Coloma, Pilar; Fernandez-Martinez, Enrique; Machado, Pedro A. N.; Zaldivar, Bryan
2016-04-07
In this work we combine information from relic abundance, direct detection, cosmic microwave background, positron fraction, gamma rays, and colliders to explore the existing constraints on couplings between Dark Matter and Standard Model constituents when no underlying model or correlation is assumed. For definiteness, we include independent vector-like effective interactions for each Standard Model fermion. Our results show that low Dark Matter masses below 20 GeV are disfavoured at the 3 σ level with respect to higher masses, due to the tension between the relic abundance requirement and upper constraints on the Dark Matter couplings. Lastly, large couplings are typically onlymore » allowed in combinations which avoid effective couplings to the nuclei used in direct detection experiments.« less
Enhancement of Compton scattering by an effective coupling constant
Barbiellini, Bernardo; Nicolini, Piero
2011-08-15
A robust thermodynamic argument shows that a small reduction of the effective coupling constant {alpha} of QED greatly enhances the low-energy Compton-scattering cross section and that the Thomson scattering length is connected to a fundamental scale {lambda}. A discussion provides a possible quantum interpretation of this enormous sensitivity to changes in the effective coupling constant {alpha}.
Coupled effects of chemotaxis and growth on traveling bacterial waves
NASA Astrophysics Data System (ADS)
Yan, Zhifeng; Bouwer, Edward J.; Hilpert, Markus
2014-08-01
Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves.
Coupled effects of chemotaxis and growth on traveling bacterial waves
NASA Astrophysics Data System (ADS)
Yan, Z.; Hilpert, M.; Bouwer, E. J.
2014-12-01
Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves.
Final State Interactions Effects in Neutrino-Nucleus Interactions
Golan, Tomasz; Juszczak, Cezary; Sobczyk, Jan T.
2012-07-01
Final State Interactions effects are discussed in the context of Monte Carlo simulations of neutrino-nucleus interactions. A role of Formation Time is explained and several models describing this effect are compared. Various observables which are sensitive to FSI effects are reviewed including pion-nucleus interaction and hadron yields in backward hemisphere. NuWro Monte Carlo neutrino event generator is described and its ability to understand neutral current $\\pi^0$ production data in $\\sim 1$ GeV neutrino flux experiments is demonstrated.
NASA Astrophysics Data System (ADS)
Cerroni, D.; Fancellu, L.; Manservisi, S.; Menghini, F.
2016-06-01
In this work we propose to study the behavior of a solid elastic object that interacts with a multiphase flow. Fluid structure interaction and multiphase problems are of great interest in engineering and science because of many potential applications. The study of this interaction by coupling a fluid structure interaction (FSI) solver with a multiphase problem could open a large range of possibilities in the investigation of realistic problems. We use a FSI solver based on a monolithic approach, while the two-phase interface advection and reconstruction is computed in the framework of a Volume of Fluid method which is one of the more popular algorithms for two-phase flow problems. The coupling between the FSI and VOF algorithm is efficiently handled with the use of MEDMEM libraries implemented in the computational platform Salome. The numerical results of a dam break problem over a deformable solid are reported in order to show the robustness and stability of this numerical approach.
Evolution of a G protein-coupled receptor response by mutations in regulatory network interactions
Di Roberto, Raphaël B.; Chang, Belinda; Trusina, Ala; Peisajovich, Sergio G.
2016-01-01
All cellular functions depend on the concerted action of multiple proteins organized in complex networks. To understand how selection acts on protein networks, we used the yeast mating receptor Ste2, a pheromone-activated G protein-coupled receptor, as a model system. In Saccharomyces cerevisiae, Ste2 is a hub in a network of interactions controlling both signal transduction and signal suppression. Through laboratory evolution, we obtained 21 mutant receptors sensitive to the pheromone of a related yeast species and investigated the molecular mechanisms behind this newfound sensitivity. While some mutants show enhanced binding affinity to the foreign pheromone, others only display weakened interactions with the network's negative regulators. Importantly, the latter changes have a limited impact on overall pathway regulation, despite their considerable effect on sensitivity. Our results demonstrate that a new receptor–ligand pair can evolve through network-altering mutations independently of receptor–ligand binding, and suggest a potential role for such mutations in disease. PMID:27487915
Evolution of a G protein-coupled receptor response by mutations in regulatory network interactions.
Di Roberto, Raphaël B; Chang, Belinda; Trusina, Ala; Peisajovich, Sergio G
2016-01-01
All cellular functions depend on the concerted action of multiple proteins organized in complex networks. To understand how selection acts on protein networks, we used the yeast mating receptor Ste2, a pheromone-activated G protein-coupled receptor, as a model system. In Saccharomyces cerevisiae, Ste2 is a hub in a network of interactions controlling both signal transduction and signal suppression. Through laboratory evolution, we obtained 21 mutant receptors sensitive to the pheromone of a related yeast species and investigated the molecular mechanisms behind this newfound sensitivity. While some mutants show enhanced binding affinity to the foreign pheromone, others only display weakened interactions with the network's negative regulators. Importantly, the latter changes have a limited impact on overall pathway regulation, despite their considerable effect on sensitivity. Our results demonstrate that a new receptor-ligand pair can evolve through network-altering mutations independently of receptor-ligand binding, and suggest a potential role for such mutations in disease. PMID:27487915
Brogi, Bharat Bhushan Ahluwalia, P. K.; Chand, Shyam
2015-06-24
Theoretical study of the Coulomb blockade effect on transport properties (Transmission Probability and I-V characteristics) for varied configuration of coupled quantum dot system has been studied by using Non Equilibrium Green Function(NEGF) formalism and Equation of Motion(EOM) method in the presence of magnetic flux. The self consistent approach and intra-dot Coulomb interaction is being taken into account. As the key parameters of the coupled quantum dot system such as dot-lead coupling, inter-dot tunneling and magnetic flux threading through the system can be tuned, the effect of asymmetry parameter and magnetic flux on this tuning is being explored in Coulomb blockade regime. The presence of the Coulomb blockade due to on-dot Coulomb interaction decreases the width of transmission peak at energy level ε + U and by adjusting the magnetic flux the swapping effect in the Fano peaks in asymmetric and symmetric parallel configuration sustains despite strong Coulomb blockade effect.
NASA Astrophysics Data System (ADS)
Donges, J. F.; Schultz, H. C. H.; Marwan, N.; Zou, Y.; Kurths, J.
2011-12-01
Network theory provides various tools for investigating the structural or functional topology of many complex systems found in nature, technology and society. Nevertheless, it has recently been realised that a considerable number of systems of interest should be treated, more appropriately, as interacting networks or networks of networks. Here we introduce a novel graph-theoretical framework for studying the interaction structure between subnetworks embedded within a complex network of networks. This framework allows us to quantify the structural role of single vertices or whole subnetworks with respect to the interaction of a pair of subnetworks on local, mesoscopic and global topological scales. Climate networks have recently been shown to be a powerful tool for the analysis of climatological data. Applying the general framework for studying interacting networks, we introduce coupled climate subnetworks to represent and investigate the topology of statistical relationships between the fields of distinct climatological variables. Using coupled climate subnetworks to investigate the terrestrial atmosphere's three-dimensional geopotential height field uncovers known as well as interesting novel features of the atmosphere's vertical stratification and general circulation. Specifically, the new measure "cross-betweenness" identifies regions which are particularly important for mediating vertical wind field interactions. The promising results obtained by following the coupled climate subnetwork approach present a first step towards an improved understanding of the Earth system and its complex interacting components from a network perspective.
Deep-subwavelength magnetic-coupling-dominant interaction among magnetic localized surface plasmons
NASA Astrophysics Data System (ADS)
Gao, Zhen; Gao, Fei; Zhang, Youming; Zhang, Baile
2016-05-01
Magnetic coupling is generally much weaker than electric Coulomb interaction. This also applies to the well-known magnetic "meta-atoms," or split-ring resonators (SRRs) as originally proposed by Pendry et al. [IEEE Trans. Microwave Theory Tech. 47, 2075 (1999), 10.1109/22.798002], in which the associated electric dipole moments usually dictate their interaction. As a result, stereometamaterials, a stack of identical SRRs, were found with electric coupling so strong that the dispersion from merely magnetic coupling was overturned. Recently, other workers have proposed a new concept of magnetic localized surface plasmons, supported on metallic spiral structures (MSSs) at a deep-subwavelength scale. Here, we experimentally demonstrate that a stack of these magnetic "meta-atoms" can have dominant magnetic coupling in both of its two configurations. This allows magnetic-coupling-dominant energy transport along a one-dimensional stack of MSSs, as demonstrated with near-field transmission measurement. Our work not only applies this type of magnetic "meta-atom" into metamaterial construction, but also provides possibilities of magnetic metamaterial design in which the electric interaction no longer takes precedence.
Hawke, B.C.
1963-02-26
This patent relates to a releasable coupling connecting a control rod to a control rod drive. This remotely operable coupling mechanism can connect two elements which are laterally and angviarly misaligned, and provides a means for sensing the locked condition of the elements. The coupling utilizes a spherical bayonet joint which is locked against rotation by a ball detent lock. (AEC)
NASA Astrophysics Data System (ADS)
Leitner, Daniel; Bodner, Gernot; Raoof, Amir
2013-04-01
, but also improve the description of the rooting environment. Until now there have been no attempts to couple root architecture and pore network models. In our work we present a first attempt to join both types of models using the root architecture model of Leitner et al., (2010) and a pore network model presented by Raoof et al. (2010). The two main objectives of coupling both models are: (i) Representing the effect of root induced biopores on flow and transport processes: For this purpose a fixed root architecture created by the root model is superimposed as a secondary root induced pore network to the primary soil network, thus influencing the final pore topology in the network generation. (ii) Representing the influence of pre-existing pores on root branching: Using a given network of (rigid) pores, the root architecture model allocates its root axes into these preexisting pores as preferential growth paths with thereby shape the final root architecture. The main objective of our study is to reveal the potential of using a pore scale description of the plant growth medium for an improved representation of interaction processes at the interface of root and soil. References Raoof, A., Hassanizadeh, S.M. 2010. A New Method for Generating Pore-Network Models. Transp. Porous Med. 81, 391-407. Leitner, D, Klepsch, S., Bodner, G., Schnepf, S. 2010. A dynamic root system growth model based on L-Systems. Tropisms and coupling to nutrient uptake from soil. Plant Soil 332, 177-192.
Approaching the strong coupling limit in single plasmonic nanorods interacting with J-aggregates
Zengin, Gülis; Johansson, Göran; Johansson, Peter; Antosiewicz, Tomasz J.; Käll, Mikael; Shegai, Timur
2013-01-01
We studied scattering and extinction of individual silver nanorods coupled to the J-aggregate form of the cyanine dye TDBC as a function of plasmon – exciton detuning. The measured single particle spectra exhibited a strongly suppressed scattering and extinction rate at wavelengths corresponding to the J-aggregate absorption band, signaling strong interaction between the localized surface plasmon of the metal core and the exciton of the surrounding molecular shell. In the context of strong coupling theory, the observed “transparency dips” correspond to an average vacuum Rabi splitting of the order of 100 meV, which approaches the plasmon dephasing rate and, thereby, the strong coupling limit for the smallest investigated particles. These findings could pave the way towards ultra-strong light-matter interaction on the nanoscale and active plasmonic devices operating at room temperature. PMID:24166360
Cost-Effectiveness of Interactive Courseware.
ERIC Educational Resources Information Center
Fletcher, J. D.
What is known about the cost effectiveness of interactive courseware (ICW) is reviewed, and issues that remain are summarized. Effect size is used for reporting the effectiveness of ICW programs. Two ICW media are considered: computer-based instruction and interactive videodisc instruction. Effect sizes for computer-based instruction have been…
Re-visit local coupling correction in the interaction regions of RHIC
Luo, Y.; Fischer, W.; Liu, C.; Marusic, A.; Minty, M.; Ptitsyn, V.; Schoefer, V.; Tepikian, S.; Trbojevic, D.; Zimmer, C.
2011-11-01
In this article we will re-visit the local coupling correction in the interaction regions (IRs) of the Relativistic Heavy Ion Collider (RHIC). We will review the measurement data of triplet quadrupole rolls, the local coupling correction strengths in the RHIC control system, and the methods for the local coupling correction with local skew quadrupole correctors. Based on the in-turnnel measurement data of triplet roll errors in 2011, we will analytically calculate and simulate IR-bump method to find out the local skew correction strengths and compare them at store and at injection with the Blue and Yellow ring lattices in the 2011 polarized proton (p-p) and Au-Au runs. The vertical dispersion from the triplet roll errors, local and global coupling correction skew quadrupoles, and the vertical dipole correctors are calculated and discussed.
Effect of random charge fluctuation on strongly coupled dusty Plasma
Issaad, M.; Rouiguia, L.; Djebli, M.
2008-09-07
Modeling the interaction between particles is an open issue in dusty plasma. We dealt with strongly coupled dust particles in two dimensional confined system. For small number of clusters, we investigate the effect of random charge fluctuation on background configuration. The study is conducted for a short rang as well as a long rang potential interaction. Numerical simulation is performed using Monte-Carlo simulation in the presence of parabolic confinement and at low temperature. We have studied the background configurations for a dust particles with constant charge and in the presence of random charge fluctuation due to the discrete nature of charge carriers. The latter is studied for a positively charged dust when the dominant charging process is due to photo-emission from the dust surface. It is found, for small classical cluster consisting of small number of particles, short rang potential gives the same result as long rang one. It is also found that the random charge fluctuation affect the background configurations.
Experimental determination of the effective strong coupling constant
Alexandre Deur; Volker Burkert; Jian-Ping Chen; Wolfgang Korsch
2007-07-01
We extract an effective strong coupling constant from low Q{sup 2} data on the Bjorken sum. Using sum rules, we establish its Q{sup 2}-behavior over the complete Q{sup 2}-range. The result is compared to effective coupling constants extracted from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constant and the calculations is not clear, the results agree surprisingly well.
Interaction-induced hopping phase in driven-dissipative coupled photonic microcavities
NASA Astrophysics Data System (ADS)
Rodriguez, S. R. K.; Amo, A.; Sagnes, I.; Le Gratiet, L.; Galopin, E.; Lemaître, A.; Bloch, J.
2016-06-01
The Bose-Hubbard model (BHM) describes bosons hopping across sites and interacting on-site. Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have recently emerged. Two coupled semiconductor microcavities constitute a model system where the hopping, interaction and decay of exciton polaritons--mixed light-matter quasiparticles--can be engineered in combination with site-selective coherent driving to implement the driven-dissipative two-site optical BHM. Here we explore the interplay of interference and nonlinearity in this system, in a regime where three distinct density profiles can be observed under identical driving conditions. We demonstrate how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields using polaritons in two-dimensional multicavity systems.
Interaction-induced hopping phase in driven-dissipative coupled photonic microcavities.
Rodriguez, S R K; Amo, A; Sagnes, I; Le Gratiet, L; Galopin, E; Lemaître, A; Bloch, J
2016-01-01
The Bose-Hubbard model (BHM) describes bosons hopping across sites and interacting on-site. Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have recently emerged. Two coupled semiconductor microcavities constitute a model system where the hopping, interaction and decay of exciton polaritons-mixed light-matter quasiparticles-can be engineered in combination with site-selective coherent driving to implement the driven-dissipative two-site optical BHM. Here we explore the interplay of interference and nonlinearity in this system, in a regime where three distinct density profiles can be observed under identical driving conditions. We demonstrate how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields using polaritons in two-dimensional multicavity systems. PMID:27307038
Interaction-induced hopping phase in driven-dissipative coupled photonic microcavities
Rodriguez, S. R. K.; Amo, A.; Sagnes, I.; Le Gratiet, L.; Galopin, E.; Lemaître, A.; Bloch, J.
2016-01-01
The Bose-Hubbard model (BHM) describes bosons hopping across sites and interacting on-site. Inspired by the success of BHM simulators with atoms in optical lattices, proposals for implementing the BHM with photons in coupled nonlinear cavities have recently emerged. Two coupled semiconductor microcavities constitute a model system where the hopping, interaction and decay of exciton polaritons—mixed light-matter quasiparticles—can be engineered in combination with site-selective coherent driving to implement the driven-dissipative two-site optical BHM. Here we explore the interplay of interference and nonlinearity in this system, in a regime where three distinct density profiles can be observed under identical driving conditions. We demonstrate how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions. Our results open new perspectives for synthesizing density-dependent gauge fields using polaritons in two-dimensional multicavity systems. PMID:27307038
NASA Technical Reports Server (NTRS)
Edwards, John W.
1996-01-01
A viscous-inviscid interactive coupling method is used for the computation of unsteady transonic flows involving separation and reattachment. A lag-entrainment integral boundary layer method is used with the transonic small disturbance potential equation in the CAP-TSDV (Computational Aeroelasticity Program - Transonic Small Disturbance) code. Efficient and robust computations of steady and unsteady separated flows, including steady separation bubbles and self-excited shock-induced oscillations are presented. The buffet onset boundary for the NACA 0012 airfoil is accurately predicted and shown computationally to be a Hopf bifurcation. Shock-induced oscillations are also presented for the 18 percent circular arc airfoil. The oscillation onset boundaries and frequencies are accurately predicted, as is the experimentally observed hysteresis of the oscillations with Mach number. This latter stability boundary is identified as a jump phenomenon. Transonic wing flutter boundaries are also shown for a thin swept wing and for a typical business jet wing, illustrating viscous effects on flutter and the effect of separation onset on the wing response at flutter. Calculations for both wings show limit cycle oscillations at transonic speeds in the vicinity of minimum flutter speed indices.
NASA Astrophysics Data System (ADS)
De Lucia, Marco; Kühn, Michael
2013-04-01
manipulations and visualization in a powerful high level language, and benefiting from an enormous amount of third-party open source R extensions. The possibility to rapidly prototype complex algorithms involving geochemical modelling is in our opinion a huge advantage. A demonstration is given by the successful evaluation of a strategy to reduce the CPU-time needed to perform reactive transport simulations in a sequential coupling scheme. The idea is the "reduction" of the number of actual chemical simulations to perform at every time step, by searching for "duplicates" of each chemical simulations in the grid: such comparison involves typically a huge number of elements (one chemical simulation for grid element for time step) and a quite large number of variables (concentrations and mineral abundances). However, through the straightforward implementation of the prototype algorithm through the R/PHREEQC interface, we found out that the scan is extremely cost-effective in terms of CPU-time and typically allows a relevant speedup for simulations starting from a homogeneous or zone-homogeneous state. This speedup can even greatily exceed that of parallelization in some favorable but not unfrequent case. This feature should therefore be implemented in reactive transport simulators. References [1] Parkhurst D, Appelo C (1999) Users guide to PHREEQC (version 2). Tech. rep, U.S. Geological Survey. [2] Beyer C, Li D, De Lucia M, Kühn M, Bauer S (2012): Modelling CO2-induced fluid-rock interactions in the Altensalzwedel gas reservoir. Part II: coupled reactive transport simulation. Environ. Earth Sci., 67, 2, 573-588. [3] R Core Team (2012) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org/. [4] Kühn M, Münch U (2012) CLEAN: CO2 Large-Scale Enhanced Gas Recovery. GEOTECHNOLOGIEN Science Report No. 19. Series: Advanced. Technologies in Earth Sciences, 199 p, ISBN 978-3-642-31676-0.
Validation of a 2-D semi-coupled numerical model for fluid-structure-seabed interaction
NASA Astrophysics Data System (ADS)
Ye, Jianhong; Jeng, Dongsheng; Wang, Ren; Zhu, Changqi
2013-10-01
A 2-D semi-coupled model PORO-WSSI 2D (also be referred as FSSI-CAS 2D) for the Fluid-Structure-Seabed Interaction (FSSI) has been developed by employing RANS equations for wave motion in fluid domain, VARANS equations for porous flow in porous structures; and taking the dynamic Biot's equations (known as "u - p" approximation) for soil as the governing equations. The finite difference two-step projection method and the forward time difference method are adopted to solve the RANS, VARANS equations; and the finite element method is adopted to solve the "u - p" approximation. A data exchange port is developed to couple the RANS, VARANS equations and the dynamic Biot's equations together. The analytical solution proposed by Hsu and Jeng (1994) and some experiments conducted in wave flume or geotechnical centrifuge in which various waves involved are used to validate the developed semi-coupled numerical model. The sandy bed involved in these experiments is poro-elastic or poro-elastoplastic. The inclusion of the interaction between fluid, marine structures and poro-elastoplastic seabed foundation is a special point and highlight in this paper, which is essentially different with other previous coupled models The excellent agreement between the numerical results and the experiment data indicates that the developed coupled model is highly reliablefor the FSSI problem.
An effect of change in patient status on marital interaction.
Roman, M; Bauman, G; Borello, J; Meltzer, B; Ehrenberg, D B
1976-06-01
In the treatment of couples and families, even more so than of individuals, therapists invariably are forced to face the problem of assessment of change in the marital or family "system." The purpose of the present study was to investigate changes in marital interaction for a special population, that is, in which one member of each married pair had been, but was no longer, a hospitalized psychiatric patient. The primary question we addressed was whether changes in marital interaction could be amply detected and whether these changes could be attributed to the particular role shift that had occurred in one spouse--from "patient" to "nonpatient." Utilizing a technique called Interaction Testing, which the senior authors devised in 1960, we found that such alterations in marital interaction do indeed arise when one member of the couple moves out of a patient role and that our instrument is useful in elucidating the nature of such effects. In addition, it can be expected that a study of this kind will be of theoretical and methodological value in dealing with the general issues of problem-solving interaction in couples and families. The clinical aspect of the study may also be expected to stimulate useful thinking regarding family theapy in hospital settings, patient management, and aftercare. PMID:1026444
DataSpaces: An Interaction and Coordination Framework for Coupled Simulation Workflows
Docan, Ciprian; Klasky, Scott A; Parashar, Manish
2010-01-01
Emerging high-performance distributed computing environments are enabling new end-to-end formulations in science and engineering that involve multiple interacting processes and data-intensive application workflows. For example, current fusion simulation efforts are exploring coupled models and codes that simultaneously simulate separate application processes, such as the core and the edge turbulence, and run on different high performance computing resources. These components need to interact, at runtime, with each other and with services for data monitoring, data analysis and visualization, and data archiving. As a result, they require efficient support for dynamic and flexible couplings and interactions, which remains a challenge. This paper presents Data-Spaces, a flexible interaction and coordination substrate that addresses this challenge. DataSpaces essentially implements a semantically specialized virtual shared space abstraction that can be associatively accessed by all components and services in the application workflow. It enables live data to be extracted from running simulation components, indexes this data online, and then allows it to be monitored, queried and accessed by other components and services via the space using semantically meaningful operators. The underlying data transport is asynchronous, low-overhead and largely memory-to-memory. The design, implementation, and experimental evaluation of DataSpaces using a coupled fusion simulation workflow is presented.
NASA Astrophysics Data System (ADS)
Kong, Xin; Forkel, Renate; Sokhi, Ranjeet S.; Suppan, Peter; Baklanov, Alexander; Gauss, Michael; Brunner, Dominik; Barò, Rocìo; Balzarini, Alessandra; Chemel, Charles; Curci, Gabriele; Jiménez-Guerrero, Pedro; Hirtl, Marcus; Honzak, Luka; Im, Ulas; Pérez, Juan L.; Pirovano, Guido; San Jose, Roberto; Schlünzen, K. Heinke; Tsegas, George; Tuccella, Paolo; Werhahn, Johannes; Žabkar, Rahela; Galmarini, Stefano
2015-08-01
This study reviews the top ranked meteorology and chemistry interactions in online coupled models recommended by an experts' survey conducted in COST Action EuMetChem and examines the sensitivity of those interactions during two pollution episodes: the Russian forest fires 25 Jul-15 Aug 2010 and a Saharan dust transport event from 1 Oct to 31 Oct 2010 as a part of the AQMEII phase-2 exercise. Three WRF-Chem model simulations were performed for the forest fire case for a baseline without any aerosol feedback on meteorology, a simulation with aerosol direct effects only and a simulation including both direct and indirect effects. For the dust case study, eight WRF-Chem and one WRF-CMAQ simulations were selected from the set of simulations conducted in the framework of AQMEII. Of these two simulations considered no feedbacks, two included direct effects only and five simulations included both direct and indirect effects. The results from both episodes demonstrate that it is important to include the meteorology and chemistry interactions in online-coupled models. Model evaluations using routine observations collected in AQMEII phase-2 and observations from a station in Moscow show that for the fire case the simulation including only aerosol direct effects has better performance than the simulations with no aerosol feedbacks or including both direct and indirect effects. The normalized mean biases are significantly reduced by 10-20% for PM10 when including aerosol direct effects. The analysis for the dust case confirms that models perform better when including aerosol direct effects, but worse when including both aerosol direct and indirect effects, which suggests that the representation of aerosol indirect effects needs to be improved in the model.
Filadi, Riccardo; Greotti, Elisa; Turacchio, Gabriele; Luini, Alberto; Pozzan, Tullio; Pizzo, Paola
2016-06-01
Communication between organelles plays key roles in cell biology. In particular, physical and functional coupling of the endoplasmic reticulum (ER) and mitochondria is crucial for regulation of various physiological and pathophysiological processes. Here, we demonstrate that Presenilin 2 (PS2), mutations in which underlie familial Alzheimer's disease (FAD), promotes ER-mitochondria coupling only in the presence of mitofusin 2 (Mfn2). PS2 is not necessary for the antagonistic effect of Mfn2 on organelle coupling, although its abundance can tune it. The two proteins physically interact, whereas their homologues Mfn1 and PS1 are dispensable for this interplay. Moreover, PS2 mutants associated with FAD are more effective than the wild-type form in modulating ER-mitochondria tethering because their binding to Mfn2 in mitochondria-associated membranes is favored. We propose a revised model for ER-mitochondria interaction to account for these findings and discuss possible implications for FAD pathogenesis. PMID:27239030
NASA Astrophysics Data System (ADS)
Chen, X.; Johnson, T. C.; Hammond, G. E.; Zachara, J. M.
2014-12-01
The hydrological and biogeochemical processes at the groundwater and river water interface are largely controlled by the exchange dynamics between the two water bodies. Accurate characterization of the heterogeneous permeability field at such interface is critical for modeling the bulk flow as well as the biogeochemical processes that are coupled with the flow. Taking advantage of the distinct conductivities in groundwater and rive water, time lapse electrical resistivity tomography (ERT) can provide rich spatial and temporal data for characterizing the permeability field, by imaging the change in subsurface electric conductivity driven by river water intrusion and retreat. We installed a large-scale (300 m by 300 m) 3-dimensional ERT array to monitor river water intrusion and retreat through time at a major river corridor, and the 4-dimensional electrical geophysical data is assimilated to invert for the underlying permeability field using ensemble-based algorithms (e.g., ensemble Kalman filter and ensemble smoother). We developed a new high-performance hydrogeophysical code by coupling an ERT imaging code E4D (Johnson et al., 2010) with a site-scale flow and transport code, PFLOTRAN (Hammond et al., 2012). The coupled code provides the key modeling capability of multi-physics processes, parallel efficiency, and multi-realization simulation capability for hydrogeophysical inversion. We assimilated both well-based point measurements of water table and specific conductance and spatially continuous ERT images in a sequential Bayesian way. Our study demonstrates the effectiveness of joint hydrogeophysical inversion for large-scale characterization of subsurface properties in the groundwater and river water interaction zone. Our investigation of spatial versus temporal data assimilation strategies have inspired systematic data worth analyses to identify the most valuable data sets for hydrogeophysical inversion. The high performance computing is performed on the Hopper
Khalil, E.M.; Abdalla, M. Sebawe . E-mail: m.sebawe@physics.org; Obada, A.S.-F.
2006-02-15
A modified Jaynes-Cummings model which consists of a two-level atom interacting with two modes of the electromagnetic field is introduced. More precisely we have considered a Hamiltonian model that includes two types of interaction: One is the field-field (frequency converter type) and the other is the atom-field interaction. By invoking a canonical transformation an exact solution of the wave function in the Schroedinger picture is obtained. The result presented in this context is used to discuss the atomic inversion as well as the entropy squeezing and variance squeezing phenomena. We have shown that the existence of the second field coupling parameter reduces the amount of squeezing in all quadratures, while the effect of the detuning parameter would lead to the superstructure phenomenon which becomes more pronounced upon increasing the mean photon numbers, in the states which are taken to be converter states.
NASA Astrophysics Data System (ADS)
Tu, Zhe-Yan; Wang, Wen-Liang; Li, Ren-Zhong; Xia, Cai-Juan; Li, Lian-Bi
2016-07-01
The CCSD(T) approach based on two-component relativistic effective core potential with spin-orbit interaction just included in coupled cluster iteration is adopted to study the spectroscopic constants of ground states of Kr2, Xe2 and Rn2 dimers. The spectroscopic constants have significant basis set dependence. Extrapolation to the complete basis set limit provides the most accurate values. The spin-orbit interaction hardly affects the spectroscopic constants of Kr2 and Xe2. However, the equilibrium bond length is shortened about 0.013 Å and the dissociation energy is augmented about 18 cm-1 by the spin-orbit interaction for Rn2 in the complete basis set limit.
Holguín-Gallego, Fernando José; Chávez-Calvillo, Rodrigo; García-Revilla, Marco; Francisco, Evelio; Pendás, Ángel Martín; Rocha-Rinza, Tomás
2016-07-15
The electronic energy partition established by the Interacting Quantum Atoms (IQA) approach is an important method of wavefunction analyses which has yielded valuable insights about different phenomena in physical chemistry. Most of the IQA applications have relied upon approximations, which do not include either dynamical correlation (DC) such as Hartree-Fock (HF) or external DC like CASSCF theory. Recently, DC was included in the IQA method by means of HF/Coupled-Cluster (CC) transition densities (Chávez-Calvillo et al., Comput. Theory Chem. 2015, 1053, 90). Despite the potential utility of this approach, it has a few drawbacks, for example, it is not consistent with the calculation of CC properties different from the total electronic energy. To improve this situation, we have implemented the IQA energy partition based on CC Lagrangian one- and two-electron orbital density matrices. The development presented in this article is tested and illustrated with the H2 , LiH, H2 O, H2 S, N2 , and CO molecules for which the IQA results obtained under the consideration of (i) the CC Lagrangian, (ii) HF/CC transition densities, and (iii) HF are critically analyzed and compared. Additionally, the effect of the DC in the different components of the electronic energy in the formation of the T-shaped (H2 )2 van der Waals cluster and the bimolecular nucleophilic substitution between F(-) and CH3 F is examined. We anticipate that the approach put forward in this article will provide new understandings on subjects in physical chemistry wherein DC plays a crucial role like molecular interactions along with chemical bonding and reactivity. © 2016 Wiley Periodicals, Inc. PMID:27237084
Electron-phonon interaction effects in tantalum
Al-Lehaibi, A.; Swihart, J.C.; Butler, W.H.; Pinski, F.J.
1987-09-15
The results of calculations for a number of electron-phonon interaction effects for tantalum are presented. The calculations are based on Korringa-Kohn-Rostoker energy bands, Born--von Karman phonons, and the rigid-muffin-tin approximation for the electron-phonon matrix element. The calculated Eliashberg spectral function ..cap alpha../sup 2/F is compared with the earlier tunneling data of Shen and the proximity tunneling data of Wolf et al. The calculated and tunneling transverse-phonon peaks agree well, but the height of the tunneling longitudinal-phonon peak is smaller than the calculated results. The calculated electron-phonon coupling parameter lambda is 0.88, which is larger than the lambda determined from superconducting tunneling and superconducting T/sub c/ measurements, but is slightly smaller than the lambda determined from electronic specific-heat measurements. Calculated phonon linewidths along various symmetry directions are presented. The temperature dependence of the electrical resistivity due to phonon scattering is calculated in the lowest-order variational approximation and it agrees with experiment. The point-contact spectral function of Kulik, G(..omega..), is determined and compared with ..cap alpha../sup 2/F(..omega..). The agreement between calculated and measured electronic specific heat and high-temperature electrical resistivity gives strong support to the validity of the rigid-muffin-tin approximation for electron-phonon matrix elements.
NASA Astrophysics Data System (ADS)
Yang, Li-Jun; Cao, Jun-Peng; Yang, Wen-Li
2015-10-01
We propose an integrable spin-1/2 Heisenberg model where the exchange couplings and Dzyloshinky-Moriya interactions are dependent on the sites. By employing the quantum inverse scattering method, we obtain the eigenvalues and the Bethe ansatz equation of the system with the periodic boundary condition. Furthermore, we obtain the exact solution and study the boundary effect of the system with the anti-periodic boundary condition via the off-diagonal Bethe ansatz. The operator identities of the transfer matrix at the inhomogeneous points are proved at the operator level. We construct the T-Q relation based on them. From which, we obtain the energy spectrum of the system. The corresponding eigenstates are also constructed. We find an interesting coherence state that is induced by the topological boundary. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174335, 11375141, 11374334, and 11434013) and the National Program for Basic Research of China and the Fund from the Chinese Academy of Sciences.
Coupled hydrodynamic model for laser-plasma interaction and hot electron generation.
Colaïtis, A; Duchateau, G; Ribeyre, X; Maheut, Y; Boutoux, G; Antonelli, L; Nicolaï, Ph; Batani, D; Tikhonchuk, V
2015-10-01
We present a formulation of the model of laser-plasma interaction (LPI) at hydrodynamical scales that couples the plasma dynamics with linear and nonlinear LPI processes, including the creation and propagation of high-energy electrons excited by parametric instabilities and collective effects. This formulation accounts for laser beam refraction and diffraction, energy absorption due to collisional and resonant processes, and hot electron generation due to the stimulated Raman scattering, two-plasmon decay, and resonant absorption processes. Hot electron (HE) transport and absorption are described within the multigroup angular scattering approximation, adapted for transversally Gaussian electron beams. This multiscale inline LPI-HE model is used to interpret several shock ignition experiments, highlighting the importance of target preheating by HEs and the shortcomings of standard geometrical optics when modeling the propagation and absorption of intense laser pulses. It is found that HEs from parametric instabilities significantly increase the shock pressure and velocity in the target, while decreasing its strength and the overall ablation pressure. PMID:26565161
Coupled hydrodynamic model for laser-plasma interaction and hot electron generation
NASA Astrophysics Data System (ADS)
Colaïtis, A.; Duchateau, G.; Ribeyre, X.; Maheut, Y.; Boutoux, G.; Antonelli, L.; Nicolaï, Ph.; Batani, D.; Tikhonchuk, V.
2015-10-01
We present a formulation of the model of laser-plasma interaction (LPI) at hydrodynamical scales that couples the plasma dynamics with linear and nonlinear LPI processes, including the creation and propagation of high-energy electrons excited by parametric instabilities and collective effects. This formulation accounts for laser beam refraction and diffraction, energy absorption due to collisional and resonant processes, and hot electron generation due to the stimulated Raman scattering, two-plasmon decay, and resonant absorption processes. Hot electron (HE) transport and absorption are described within the multigroup angular scattering approximation, adapted for transversally Gaussian electron beams. This multiscale inline LPI-HE model is used to interpret several shock ignition experiments, highlighting the importance of target preheating by HEs and the shortcomings of standard geometrical optics when modeling the propagation and absorption of intense laser pulses. It is found that HEs from parametric instabilities significantly increase the shock pressure and velocity in the target, while decreasing its strength and the overall ablation pressure.
Entanglement Criteria of Two Two-Level Atoms Interacting with Two Coupled Modes
NASA Astrophysics Data System (ADS)
Baghshahi, Hamid Reza; Tavassoly, Mohammad Kazem; Faghihi, Mohammad Javad
2015-08-01
In this paper, we study the interaction between two two-level atoms and two coupled modes of a quantized radiation field in the form of parametric frequency converter injecting within an optical cavity enclosed by a medium with Kerr nonlinearity. It is demonstrated that, by applying the Bogoliubov-Valatin canonical transformation, the introduced model is reduced to a well-known form of the generalized Jaynes-Cummings model. Then, under particular initial conditions for the atoms (in a coherent superposition of its ground and upper states) and the fields (in a standard coherent state) which may be prepared, the time evolution of state vector of the entire system is analytically evaluated. In order to understand the degree of entanglement between subsystems (atom-field and atom-atom), the dynamics of entanglement through different measures, namely, von Neumann reduced entropy, concurrence and negativity is evaluated. In each case, the effects of Kerr nonlinearity and detuning parameter on the above measures are numerically analyzed, in detail. It is illustrated that the amount of entanglement can be tuned by choosing the evolved parameters, appropriately.
NASA Astrophysics Data System (ADS)
Hatefi, Ehsan
2015-12-01
We evaluate five point world-sheet string theory amplitudes of one transverse scalar field, two world volume gauge fields (and two transverse scalars, a gauge field) in the presence of a closed string Ramond-Ramond vertex operator in its symmetric picture. We carry out all the entire S-matrix elements of five point mixed RR-scalars/gauge fields < C -1 ϕ 0 A -1 A 0>, < C -1 ϕ -1 A 0 A 0>, < C -1 A 0 ϕ -1 ϕ 0> and < C -1 A -1 ϕ 0 ϕ 0> in detail and start comparing all order α' contact interactions and singularities in both transverse and world volume directions. We explore the presence of various new couplings in string theory effective actions and find out their all order α' higher derivative corrections in both type IIA and IIB. Ultimately we make various remarks for the singularities and contact terms whose RR momenta are embedded in transverse directions. α' corrections to some of Myers terms are also addressed.
Interchannel coupling effects in the valence photoionization of SF6
NASA Astrophysics Data System (ADS)
Jose, Jobin; Lucchese, Robert; Rescigno, Tom
2014-05-01
The complex Kohn and polyatomic Schwinger variational techniques have been employed to illustrate the interchannel coupling correlation effects in the valence photoionization dynamics of SF6. Partial photoionization cross sections and asymmetry parameters of six valence subshells (1t1 g, 5t1 u, 1t2 u, 3eg, 1t2 g, 4t1 u) are discussed in the framework of several theoretical and experimental studies. The complex Kohn results are in rather good agreement with experimental results, indicative of the fact that the interchannel coupling effects alter the photoionization dynamics significantly. We find that the dominant effect of interchannel coupling is to reduce the magnitude of shape resonant cross sections near threshold and to induce resonant features in other channels to which resonances are coupled.
Effect of interfacial coupling on rectification in organic spin rectifiers
NASA Astrophysics Data System (ADS)
Hu, Gui-Chao; Zuo, Meng-Ying; Li, Ying; Zhang, Zhao; Ren, Jun-Feng; Wang, Chuan-Kui
2015-07-01
The effect of interfacial coupling on rectification in an organic co-oligomer spin diode is investigated theoretically by considering spin-independent and spin-resolved couplings respectively. In the case of spin-independent coupling, an optimal interfacial coupling strength with a significant enhanced rectification ratio is found, whose value depends on the structural asymmetry of the molecule. In the case of spin-resolved coupling, we found that only the variation of the interfacial coupling with specific spin is effective to modulate the rectification, which is due to the spin-filtering property of the central asymmetric magnetic molecule. A transition of the spin-current rectification between parallel spin-current rectification and antiparallel spin-current rectification may be observed with the variation of the spin-resolved interfacial coupling. The interfacial effect on rectification is further analyzed from the spin-dependent transmission spectrum at different biases. Project supported by the National Natural Science Foundation of China (Grant No. 1374195), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AM017), and the Excellent Young Scholars Research Fund of Shandong Normal University, China.
Bertone, G.; Cerdeno, D. G.; Collar, J. I.; Odom, B.
2007-10-12
We study the prospects for detecting weakly interacting massive particles (WIMPs) in a number of phenomenological scenarios, with a detector composed of a target simultaneously sensitive to both spin-dependent and spin-independent couplings, as is the case of COUPP (Chicagoland Observatory for Underground Particle Physics). First, we show that sensitivity to both couplings optimizes chances of initial WIMP detection. Second, we demonstrate that, in case of detection, a comparison of the signal on two complementary targets, such as in COUPP CF{sub 3}I and C{sub 4}F{sub 10} bubble chambers, allows a significantly more precise determination of the dark matter axial and scalar couplings. This strategy would provide crucial information on the nature of the WIMPs and possibly allow discrimination between neutralino and Kaluza-Klein dark matter.
Floyd, Frank J.; Daugherty, Michelle Klotz; Fitzgerald, Hiram H.; Cranford, James A.; Zucker, Robert A.
2008-01-01
The authors examined problem-solving marital interactions of alcoholic and nonalcoholic couples (N = 132). Four alcoholic groups (husband alcoholic with antisocial personality disorder or not, paired with alcoholic or nonalcoholic wives) were compared with each other and with a both-spouses-nonalcoholic group. Consistent with the alcoholic subtypes hypothesis, couples with an antisocial alcoholic husband had higher levels of hostile behavior regardless of wives’ alcoholism status. In contrast, rates of positive behaviors and the ratio of positive to negative behaviors were greatest among couples in which either both or neither of the spouses had alcoholic diagnoses and were lowest among alcoholic husbands with nonalcoholic wives. Discussion focuses on possible mechanisms linking antisocial alcoholism and discrepant alcoholic diagnoses to poorer marital outcomes. PMID:16492103
Synchronization and plateau splitting of coupled oscillators with long-range power-law interactions
NASA Astrophysics Data System (ADS)
Kuo, Huan-Yu; Wu, Kuo-An
2015-12-01
We investigate synchronization and plateau splitting of coupled oscillators on a one-dimensional lattice with long-range interactions that decay over distance as a power law. We show that in the thermodynamic limit the dynamics of systems of coupled oscillators with power-law exponent α ≤1 is identical to that of the all-to-all coupling case. For α >1 , oscillatory behavior of the phase coherence appears as a result of single plateau splitting into multiple plateaus. A coarse-graining method is used to investigate the onset of plateau splitting. We analyze a simple oscillatory state formed by two plateaus in detail and propose a systematic approach to predict the onset of plateau splitting. The prediction of breaking points of plateau splitting is in quantitatively good agreement with numerical simulations.
NASA Astrophysics Data System (ADS)
Fatehi, Shervin; Alguire, Ethan; Shao, Yihan; Subotnik, Joseph E.
2011-12-01
We present a method for analytically calculating the derivative couplings between a pair of configuration-interaction-singles (CIS) excited states obtained in an atom-centered basis. Our theory is exact and has been derived using two completely independent approaches: one inspired by the Hellmann-Feynman theorem and the other following from direct differentiation. (The former is new, while the latter is in the spirit of existing approaches in the literature.) Our expression for the derivative couplings incorporates all Pulay effects associated with the use of an atom-centered basis, and the computational cost is minimal, roughly comparable to that of a single CIS energy gradient. We have validated our method against CIS finite-difference results and have applied it to the lowest lying excited states of naphthalene; we find that naphthalene derivative couplings include Pulay contributions sufficient to have a qualitative effect. Going beyond standard problems in analytic gradient theory, we have also constructed a correction, based on perturbative electron-translation factors, for including electronic momentum and eliminating spurious components of the derivative couplings that break translational symmetry. This correction is general and can be applied to any level of electronic structure theory.
NASA Astrophysics Data System (ADS)
Sunaga, A.; Abe, M.; Hada, M.; Das, B. P.
2016-04-01
The scalar-pseudoscalar (S-PS) interaction, which has been predicted between the electrons and nuclei of atoms and molecules, violates parity- (P -) and time- (T -) reversal symmetries. The electric dipole moment of the electron (eEDM) and the S-PS interaction together give rise to an energy shift in paramagnetic polar molecules, which in principle can be measured. The determination of the S-PS interaction constant, ks ,A, for an atom A could be a sensitive probe of physics beyond the standard model. The upper limit for it can be obtained by combining the results of the measured energy shift mentioned above and the accurate quantum chemical calculation of the S-PS coefficient, Ws ,A. In this work, we use a method based on the four-component relativistic coupled-cluster singles and doubles (RCCSD) method to calculate this coefficient for YbF, one of the most promising candidates for the search of the eEDM and the S-PS interaction. We obtain Ws ,Yb=-40.5 (kHz ) with an estimated error of less than 10% for YbF. We also calculate the effective electric field (Eeff), the molecular dipole moment, and the parallel component of the hyperfine coupling constant (A∥) by the RCCSD method. The discrepancies in the results of these calculations with those of accurate measurements are used to estimate the accuracy of our calculation of Ws ,Yb.
Final Report. Coupled simulations of Antarctic Ice-sheet/ocean interactions using POP and CISM
Asay-Davis, Xylar Storm
2015-12-30
The project performed under this award, referred to from here on as CLARION (CoupLed simulations of Antarctic Ice-sheet/Ocean iNteractions), included important advances in two models of ice sheet and ocean interactions. Despite its short duration (one year), the project made significant progress on its three major foci. First, together with collaborator Daniel Martin at Lawrence Berkeley National Laboratory (LBNL), I developed the POPSICLES coupled ice sheet-ocean model to the point where it could perform a number of pan-Antarctic simulations under various forcing conditions. The results were presented at a number of major conferences and workshops worldwide, and are currently being incorporated into two manuscripts in preparation.
Stability and Chaos of Two Coupled Bose-Einstein Condensates with Three-Body Interaction
NASA Astrophysics Data System (ADS)
Li, Ya; Hai, Wen-Hua
2005-11-01
We study the dynamics of two Bose-Einstein condensates (BECs) tunnel-coupled by a double-well potential. A real three-body interaction term is considered and a two-mode approximation is used to derive two coupled equations, which describe the relative population and relative phase. By solving the equations and analyzing the stability of the system, we find the stable stationary solutions for a constant atomic scattering length. When a periodically time-varying scattering length is applied, Melnikov analysis and numerical calculation demonstrate the existence of chaotic behavior and the dependence of chaos on the three-body interaction parameters. The project supported by National Natural Science Foundation of China under Grant No. 10275023 and the Laboratory of Magnetic Resonance and Atomic and Molecular Physics of China under Grant No. T152504
Uncertainty quantification of effective nuclear interactions
NASA Astrophysics Data System (ADS)
Pérez, R. Navarro; Amaro, J. E.; Arriola, E. Ruiz
2016-03-01
We give a brief review on the development of phenomenological NN interactions and the corresponding quantification of statistical uncertainties. We look into the uncertainty of effective interactions broadly used in mean field calculations through the Skyrme parameters and effective field theory counterterms by estimating both statistical and systematic uncertainties stemming from the NN interaction. We also comment on the role played by different fitting strategies on the light of recent developments.
NASA Astrophysics Data System (ADS)
Sahoo, Sharmistha; Zhang, Zhao; Teo, Jeffrey
Time reversal symmetric topological superconductors in three spatial dimensions carry gapless surface Majorana fermions. They are robust against any time reversal symmetric single-body perturbation weaker than the bulk energy gap. We mimic the massless surface Majorana's by coupled wire models in two spatial dimensions. We introduce explicit many-body interwire interactions that preserve time reversal symmetry and give energy gaps to all low energy degrees of freedom. The gapping 4-fermion interactions are constructed by interwire Kac-Moody current backscattering and rely on the fractionalization or conformal embedding of the Majorana wires.
Wang, Shu-Wen; Repetti, Rena L
2016-06-01
We examined sex differences in explicitly supportive behavior exchanges between husbands and wives using naturalistic video-recordings of everyday couple interactions inside the home. Thirty dual-earner, middle class, heterosexual couples with school-age children were recorded in their homes over 4 days. Specific instances of face-to-face explicit couple support in the video-recordings were identified, and the support role assumed by each partner (recipient vs. provider), the method of support initiation (solicitations vs. offers), and the type of support (instrumental vs. emotional) in each interaction were coded. Paired samples t tests examined sex differences in husbands' and wives' supportive behavior, and bivariate correlations tested the associations among spouses' support initiation behaviors. Findings counter prior research that has largely found a "support gap" favoring husbands as support recipients. Instead, results indicate that wives received significantly more support of an instrumental nature from husbands (than husbands did from wives), a finding driven by wives' active support-soliciting behavior. Among husbands, a tendency to be the solicitor of support was positively correlated with a tendency to offer support. Within couples, rates of offers of support by 1 spouse were correlated with offers by the partner. Naturalistic observations highlight processes that may not be detected by self-reports or laboratory data, in an ecologically valid context in which social behavior reflects the natural rhythms and pulls of everyday life. (PsycINFO Database Record PMID:27010600
Knobloch-Fedders, Lynne M; Critchfield, Kenneth L; Boisson, Tania; Woods, Naomi; Bitman, Rachel; Durbin, C Emily
2014-04-01
This study investigated the associations among depression, relationship quality, and demand/withdraw and demand/submit behavior in couples' conflict interactions. Two 10-min conflict interactions were coded for each couple (N = 97) using Structural Analysis of Social Behavior (SASB; Benjamin, 1979a, 1987, 2000a). Depression was assessed categorically (via the presence of depressive disorders) and dimensionally (via symptom reports). Results revealed that relationship quality was negatively associated with demanding behavior, as well as receiving submissive or withdrawing behavior from one's partner. Relationship quality was positively associated with withdrawal. Demanding behavior was positively associated with women's depression symptoms but negatively associated with men's depression symptoms. Sequential analysis revealed couples' behavior was highly stable across time. Initiation of demand/withdraw and demand/submit sequences were negatively associated with partners' relationship adjustment. Female demand/male withdraw was positively associated with men's depression diagnosis. Results underscore the importance of sequential analysis when investigating associations among depression, relationship quality, and couples' interpersonal behavior. PMID:24749515
Frisch, E.; Johnson, C.G.
1962-05-15
A detachable coupling arrangement is described which provides for varying the length of the handle of a tool used in relatively narrow channels. The arrangement consists of mating the key and keyhole formations in the cooperating handle sections. (AEC)
Climate-chemical interactions and greenhouse effects of trace gases
NASA Technical Reports Server (NTRS)
Shi, Guang-Yu; Fan, Xiao-Biao
1994-01-01
A completely coupled one-dimensional radiative-convective (RC) and photochemical-diffusion (PC) model has been developed recently and used to study the climate-chemical interactions. The importance of radiative-chemical interactions within the troposphere and stratosphere has been examined in some detail. We find that increases of radiatively and/or chemically active trace gases such as CO2, CH4 and N2O have both the direct effects and the indirect effects on climate change by changing the atmospheric O3 profile through their interaction with chemical processes in the atmosphere. It is also found that the climatic effect of ozone depends strongly on its vertical distribution throughout the troposphere and stratosphere, as well on its column amount in the atmosphere.
Effect of spin rotation coupling on spin transport
Chowdhury, Debashree Basu, B.
2013-12-15
We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k{sup →}⋅p{sup →} perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k{sup →}⋅p{sup →} framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied.
A Coupled Fluid-Structure Interaction Analysis of Solid Rocket Motor with Flexible Inhibitors
NASA Technical Reports Server (NTRS)
Yang, H. Q.; West, Jeff
2014-01-01
A capability to couple NASA production CFD code, Loci/CHEM, with CFDRC's structural finite element code, CoBi, has been developed. This paper summarizes the efforts in applying the installed coupling software to demonstrate/investigate fluid-structure interaction (FSI) between pressure wave and flexible inhibitor inside reusable solid rocket motor (RSRM). First a unified governing equation for both fluid and structure is presented, then an Eulerian-Lagrangian framework is described to satisfy the interfacial continuity requirements. The features of fluid solver, Loci/CHEM and structural solver, CoBi, are discussed before the coupling methodology of the solvers is described. The simulation uses production level CFD LES turbulence model with a grid resolution of 80 million cells. The flexible inhibitor is modeled with full 3D shell elements. Verifications against analytical solutions of structural model under steady uniform pressure condition and under dynamic condition of modal analysis show excellent agreements in terms of displacement distribution and eigen modal frequencies. The preliminary coupled result shows that due to acoustic coupling, the dynamics of one of the more flexible inhibitors shift from its first modal frequency to the first acoustic frequency of the solid rocket motor.
Rashba spin-orbit coupling effects in armchair graphene nanoribbons
Prabhakar, S.; Melnik, R.; Sebetci, A.
2015-03-30
We study the influence of the Rashba spin-orbit coupling effects on the electronic properties of armchair graphene nanoribbons (GNRs). By utilizing both analytical and numerical schemes, we show that the finite width of the graphene nanoribbon breaks its energy spectrum into an infinite number of bands. By considering the Rashba spin-orbit coupling term as a perturbation, we show that zero energy bands between electron and hole states at Dirac points are lifted into a finite bandgap.
NASA Astrophysics Data System (ADS)
Chiolerio, Alessandro; Allia, Paolo; Graziano, Mariagrazia
2012-09-01
Physical limitations foreshadow the eventual end to traditional Complementary Metal Oxide Semiconductor (CMOS) scaling. Therefore, interest has turned to various materials and technologies aimed to succeed to traditional CMOS. Magnetic Quantum dot Cellular Automata (MQCA) are one of these technologies. Working MQCA arrays require very complex techniques and an excellent control on the geometry of the nanomagnets and on the quality of the magnetic thin film, thus limiting the possibility for MQCA of representing a definite solution to cost-effective, high density and low power consumption device demand. Counter-intuitively, moving towards bigger sizes and lighter technologies it is still possible to develop multi-state logic devices, as we demonstrated, whose main advantage is cost-effectiveness. Applications may be seen in low cost logic devices where integration and computational power are not the main issue, eventually using flexible substrates and taking advantage of the intrinsic mechanical toughness of systems where long range interactions do not need wirings. We realized cobalt micrometric MQCA arrays by means of Electron Beam Lithography, exploiting cost-effective processes such as lift-off and RF sputtering that usually are avoided due to their low control on array geometry and film roughness. Information relative to the magnetic configuration of MQCA elements including their eventual magnetic interactions was obtained from Magnetic Force Microscope (MFM) images, enhanced by means of a numerical procedure and presented in differential maps. We report the existence of bi-stable magnetic patterns, as detected by MFM while sampling the z-component of magnetic induction field, arising from dipolar inter-element magnetostatic coupling, able to store and propagate binary information. This is achieved despite the array quality and element magnetic state, which are low and multi-domain, respectively. We discuss in detail shape, inter-element spacing and dot profile
Effects of subducted seamount on interplate coupling and earthquakes
NASA Astrophysics Data System (ADS)
Yang, H.; Liu, Y.; Lin, J.
2011-12-01
It has been proposed that large seamounts riding on a subducting plate may play a critical role in controlling the characteristics of earthquakes in a subduction zone, including the maximum sizes of the potential mega-earthquakes. However, the specific relationships between subducted seamounts and megathrust earthquakes are still poorly understood. Here we conduct a numerical investigation of the physical interaction of subducted seamounts with a subduction zone by considering the rate and state friction properties of the subducting interface, and complete stressing cycles of earthquake faults. The seamount is incorporated as additional normal stress into the model. The preliminary results from a 2D Cascadia-like subduction fault model show: (1) The subducted seamount acts as a "barrier" if the seamount is sitting up-dip to the earthquake nucleation zone, regardless of the seamount size. When the seamount is subducted adjacent to the nucleation zone, a higher additional effective normal stress is required to impede ruptures. (2) The higher the additional effective normal stress caused by the seamount is, the larger coseismic slip may be released by a large earthquake when rupturing the whole seismogenic zone in different earthquake cycles, suggesting that the "barrier" seamount also enhances the seismic coupling. (3) The seamount could turn into an "asperity" that initiates seismic ruptures if it is preceded by a deeper and smaller rupture. In addition, the seamount may also cause stress transfer on the fault which leads to earthquakes nucleated in the shallow part of the seismogenic zone. (4) If the seamount is subducted to the nucleation zone, megathrust earthquakes can still occur and will release larger coseismic slip, indicating the enhancement of seismic coupling between the overriding and subducting plates. (5) If it is subducted beneath the seismogenic zone, the seamount had little effects on the characteristics of megathrust earthquakes and the coseismic
The Effect of Water on Crack Interaction
NASA Astrophysics Data System (ADS)
Gaede, O.; Regenauer-Lieb, K.
2009-04-01
While the mechanical coupling between pore fluid and solid phase is relatively well understood, quantitative studies dealing with chemical-mechanical weakening in geological materials are rare. Many classical poroelastic problems can be addressed with the simple law of effective stress. Experimental studies show that the presence of a chemically active fluid can have effects that exceed the predictions of the law of effective stress. These chemical fluid-rock interactions alter the mechanical properties of the solid phase. Especially chemical-mechanical weakening has important ramifications for many areas of applied geosciences ranging from nuclear waste disposal over reservoir enhancement to fault stability. In this study, we model chemically induced changes of the size of the process zone around a crack tip. The knowledge of the process zone size is used to extend existing effective medium approximations of cracked solids. The stress distribution around a crack leads to a chemical potential gradient. This gradient will be a driver for mass diffusion through the solid phase. As an example, mass diffusion is towards the crack tip for a mode I crack. In this case a chemical reaction, that weakens the solid phase, will increase the size of the process zone around the crack tip. We apply our model to the prominent hydrolytic weakening effect observed in the quartz-water system (Griggs and Blacic, 1965). Hydrolytic weakening is generally attributed to water hydrolyzing the strong Si-O bonds of the quartz crystal. The hydrolysis replaces a Si-O-Si bridge with a relatively weak hydrogen bridge between two silanol groups. This enhances dislocation mobility and hence the yield stress is reduced. The plastic process zone around a crack tip is therefore larger in a wet crystal than in a dry crystal. We calculate the size of the process zone by solving this coupled mechanical-chemical problem with the Finite Element code ABAQUS. We consider single crack, collinear crack and
Exploring the effects of sexual desire discrepancy among married couples.
Willoughby, Brian J; Farero, Adam M; Busby, Dean M
2014-04-01
Previous studies have found associations between the individual discrepancy of desired sexual frequency and actual sexual frequency and relational outcomes among premarital couples. The present study extended this research by using a sample of 1,054 married couples to explore how actor and partner individual sexual desire discrepancy (SDD) scores were associated with relationship satisfaction, stability, communication, and conflict during marriage. All participants took an online survey which assessed both couple sexual dynamics and relationship outcomes. Findings suggested that higher actor individual SDD was generally associated with negative relational outcomes, including lower reported relationship satisfaction, stability, and more reported couple conflict. These effects were found after controlling for background factors, baseline sexual frequency and desire, and couple desire discrepancies. Some partner effects were also found and were generally in the same direction. Marital length did not moderate the effects found although gender moderated associations between individual SDD and reported couple communication. Negative associations between individual SDD and communication were particularly strong when the husband reported high discrepancies between desired and actual sexual frequency. Results suggested that higher individual sexual desire discrepancies among married individuals may undermine relationship well-being. Applications of these findings to a clinical setting are also discussed. PMID:24045904
Yu, Yong; Reed, Robin
2015-01-01
Pre-mRNA splicing is coupled to transcription by RNA polymerase II (RNAP II). We previously showed that U1 small nuclear ribonucleoprotein (snRNP) associates with RNAP II, and both RNAP II and U1 snRNP are also the most abundant factors associated with the protein fused-in-sarcoma (FUS), which is mutated to cause the neurodegenerative disease amyotrophic lateral sclerosis. Here, we show that an antisense morpholino that base-pairs to the 5′ end of U1 snRNA blocks splicing in the coupled system and completely disrupts the association between U1 snRNP and both FUS and RNAP II, but has no effect on the association between FUS and RNAP II. Conversely, we found that U1 snRNP does not interact with RNAP II in FUS knockdown extracts. Moreover, using these extracts, we found that FUS must be present during the transcription reaction in order for splicing to occur. Together, our data lead to a model that FUS functions in coupling transcription to splicing via mediating an interaction between RNAP II and U1 snRNP. PMID:26124092
NASA Technical Reports Server (NTRS)
Fan, An-Fu; Sun, Nian-Chun; Zhou, Xin
1996-01-01
The Phase-dynamical properties of the squeezed vacuum state intensity-couple interacting with the two-level atom in an ideal cavity are studied using the Hermitian phase operator formalism. Exact general expressions for the phase distribution and the associated expectation value and variance of the phase operator have been derived. we have also obtained the analytic results of the phase variance for two special cases-weakly and strongly squeezed vacuum. The results calculated numerically show that squeezing has a significant effect on the phase properties of squeezed vacuum.
Rao, Soniya S; Gejji, Shridhar P
2016-07-21
Noncovalent interactions accompanying phenylalanine (Phe), tryptophan (Trp), and tyrosine (Tyr) amino acids based ionic liquids (AAILs) composed of 1-methyl-3-butyl-imidazole and its methyl-substituted derivative as cations have been analyzed employing the dispersion corrected density functional theory. It has been shown that cation-anion binding in these bioionic ILs is primarily facilitated through hydrogen bonding in addition to lp---π and CH---π interactions those arising from aromatic moieties which can be probed through (1)H and (13)C NMR spectra calculated from the gauge independent atomic orbital method. Characteristic NMR spin-spin coupling constants across hydrogen bonds of ion pair structures viz., Fermi contact, spin-orbit and spin-dipole terms show strong dependence on mutual orientation of cation with the amino acid anion. The spin-spin coupling mechanism transmits spin polarization via electric field effect originating from lp---π interactions whereas the electron delocalization from lone pair on the carbonyl oxygen to antibonding C-H orbital is facilitated by hydrogen bonding. It has been demonstrated that indirect spin-spin coupling constants across the hydrogen bonds correlate linearly with hydrogen bond distances. The binding energies and dissected nucleus independent chemical shifts (NICS) document mutual reduction of aromaticity of hydrogen bonded ion pairs consequent to localization of π-character. Moreover the nature and type of such noncovalent interactions governing the in-plane and out-of-plane NICS components provide a measure of diatropic and paratropic currents for the aromatic rings of varying size in AAILs. Besides the direction of frequency shifts of characteristic C═O and NH stretching vibrations in the calculated vibrational spectra has been rationalized. PMID:27336283
Magnetic domain wall creep in the presence of an effective interlayer coupling field
NASA Astrophysics Data System (ADS)
Metaxas, P. J.; Jamet, J. P.; Ferré, J.; Rodmacq, B.; Dieny, B.; Stamps, R. L.
We investigate thermally activated domain wall creep in a system consisting of two ultrathin Co layers with perpendicular anisotropy coupled antiferromagnetically through a 4 nm thick Pt spacer layer. The field driven dynamics of domain walls in the softer Co layer have been measured while keeping the harder Co layer negatively saturated. The effect of the interlayer interaction on the soft layer is interpreted in terms of an effective coupling field, HJ, which results in an asymmetry between the domain wall speeds measured under positive and negative driving fields. We show that creep theory remains valid to describe the observed wall motion when the effective coupling field is included in the creep velocity law as a component of the total field acting on the wall. Using the resultant modified creep expression, we determine a value for the effective coupling field which is consistent with that measured from the shift of the soft layer's minor hysteresis loop. The net antiferromagnetic coupling is attributed to a combination of RKKY and orange-peel coupling.
NASA Astrophysics Data System (ADS)
Larsen, Helena; Olsen, Jeppe; Hättig, Christof; Jørgensen, Poul; Christiansen, Ove; Gauss, Jürgen
1999-08-01
Static and frequency-dependent polarizabilities and first hyperpolarizabilities have been calculated for HF and Ne using full configuration interaction (FCI) and a hierarchy of coupled cluster models: coupled cluster singles (CCS), an approximate coupled cluster singles and doubles model (CC2), coupled cluster singles and doubles (CCSD), an approximate coupled cluster singles, doubles, and triples model (CC3), and coupled cluster singles, doubles, and triples (CCSDT). A previous study of BH concerning FCI benchmarking has been extended to include CC3 and static CCSDT values. Systematic improvements of the polarizabilities and the hyperpolarizabilities are found going from CCS to CCSD and from CCSD to CC3 or CCSDT. Little or no improvement of the polarizabilities and no improvement of the hyperpolarizabilities are seen when going from CCS to CC2. The CCSD results represent a significant improvement over CCS and CC2 but are again surpassed by the CC3 results which agree very well with the FCI values. The relative error for the static polarizability at the CC3 level is 0.11% for Ne and, respectively, 0.16% and 0.20% for αxx and αzz of HF. For βzzz and βzxx the errors are 0.50% and 1.7%, respectively. Only in the challenging case of BH does CCSDT improve the CC3 values. The dispersion for the polarizabilities and hyperpolarizabilities is predicted with increasing accuracy in the CCS-CC2-CCSD-CC3 sequence as expected from the increasing accuracy of the electronic excitation energies. For all molecules the effect of orbital relaxation has been investigated for the static properties. The inclusion of orbital relaxation gives results that are somewhat different from the unrelaxed results but are in general no improvement.
NASA Astrophysics Data System (ADS)
Yu, Yue; Luo, Zhuxi; Wang, Ziqiang
2014-07-01
We show that the dipole-dipole coupling between Wannier modes in cigar-shaped Bose-Einstein condensates (BECs) is significantly enhanced while the short-range coupling is strongly suppressed. As a result, the dipole-dipole interaction can become the dominant interaction between ultracold alkali Bose atoms. In the long length limit of a cigar-shaped BEC, the resulting effective one-dimensional models possess an effective inverse squared interacting potential, the Calogero-Sutherland potential, which plays a fundamental role in many fields of contemporary physics; but its direct experimental realization has been a challenge for a long time. We propose to realize the Calogero-Sutherland model in ultracold alkali Bose atoms and study the effects of the dipole-dipole interaction.
Qi, Cai; Zhang, Hong; Liu, Li; Yang, Yinke; Kang, Tengfei; Hao, Wenxin; Jin, Gang; Jiang, Taijiao
2014-01-01
The soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins are small and abundant membrane-bound proteins, whose specific interactions mediate membrane fusion during cell fusion or cellular trafficking. In this study, we report the use of a label-free method, called imaging ellipsometer to analyze the interactions among three SNAREs, namely Sec22p, Ykt6p and Sso2p. The SNAREs were immobilized on the silicon wafer and then analyzed in a pairwise mode with microfluidic array, leading us to discover the interactions between Ykt6p and Sso2p, Sec22p and Sso2p. Moreover, by using the real-time function of the imaging ellipsometer, we were able to obtain their association constants (KA) of about 104 M−1. We argue that the use of imaging ellipsometer coupled with microfluidic device will deepen our understanding of the molecular mechanisms underlying membrane fusion process. PMID:24938428
Gate-tunable indirect exchange interaction in spin-orbit-coupled mesoscopic rings
NASA Astrophysics Data System (ADS)
Nikoofard, H.; Heidari Semiromi, E.
2015-05-01
We study the carrier-mediated exchange interaction, the so-called Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, between two magnetic impurity moments embedded in a semiconductor mesoscopic ring. We treat the ring in the presence of an Aharonov-Bohm-type magnetic flux and the Rashba and Dresselhaus spin-orbit interactions (RSOI and DSOI). Energy eigenvalues of the system are obtained within a tight-binding framework and the strength of the indirect exchange interaction vs. RSOI strengths are plotted for different values of DSOI strength. The results show that the type of the impurity magnetic order, ferromagnetic (F) or antiferromagnetic (AF), depends on the RSOI and DSOI strengths. This leads to a full electrical control on the magnetic alignment of the system through, e.g., an external gate voltage.
Effect of acoustic coupling on random and harmonic plate vibrations
NASA Technical Reports Server (NTRS)
Frendi, Abdelkader; Robinson, Jay
1993-01-01
The effect of acoustic coupling on random and harmonic plate vibrations is studied using two numerical models. In the coupled model, the plate response is obtained by integration of the nonlinear plate equation coupled with the nonlinear Euler equations for the surrounding acoustic fluid. In the uncoupled model, the nonlinear plate equation with an equivalent linear viscous damping term is integrated to obtain the response of the plate subject to the same excitation field. For a low-level, narrow-band excitation, the two models predict the same plate response spectra. As the excitation level is increased, the response power spectrum predicted by the uncoupled model becomes broader and more shifted towards the high frequencies than that obtained by the coupled model. In addition, the difference in response between the coupled and uncoupled models at high frequencies becomes larger. When a high intensity harmonic excitation is used, causing a nonlinear plate response, both models predict the same frequency content of the response. However, the level of the harmonics and subharmonics are higher for the uncoupled model. Comparisons to earlier experimental and numerical results show that acoustic coupling has a significant effect on the plate response at high excitation levels. Its absence in previous models may explain the discrepancy between predicted and measured responses.
Coupled Fluid-Structure Interaction Analysis of Solid Rocket Motor with Flexible Inhibitors
NASA Technical Reports Server (NTRS)
Yang, H. Q.; West, Jeff; Harris, Robert E.
2014-01-01
Flexible inhibitors are generally used in solid rocket motors (SRMs) as a means to control the burning of propellant. Vortices generated by the flow of propellant around the flexible inhibitors have been identified as a driving source of instabilities that can lead to thrust oscillations in launch vehicles. Potential coupling between the SRM thrust oscillations and structural vibration modes is an important risk factor in launch vehicle design. As a means to predict and better understand these phenomena, a multidisciplinary simulation capability that couples the NASA production CFD code, Loci/CHEM, with CFDRC's structural finite element code, CoBi, has been developed. This capability is crucial to the development of NASA's new space launch system (SLS). This paper summarizes the efforts in applying the coupled software to demonstrate and investigate fluid-structure interaction (FSI) phenomena between pressure waves and flexible inhibitors inside reusable solid rocket motors (RSRMs). The features of the fluid and structural solvers are described in detail, and the coupling methodology and interfacial continuity requirements are then presented in a general Eulerian-Lagrangian framework. The simulations presented herein utilize production level CFD with hybrid RANS/LES turbulence modeling and grid resolution in excess of 80 million cells. The fluid domain in the SRM is discretized using a general mixed polyhedral unstructured mesh, while full 3D shell elements are utilized in the structural domain for the flexible inhibitors. Verifications against analytical solutions for a structural model under a steady uniform pressure condition and under dynamic modal analysis show excellent agreement in terms of displacement distribution and eigenmode frequencies. The preliminary coupled results indicate that due to acoustic coupling, the dynamics of one of the more flexible inhibitors shift from its first modal frequency to the first acoustic frequency of the solid rocket motor
Fleig, Timo
2005-11-15
This study reports static electric dipole polarizabilities of the group 13 atoms in their lowest J=(1/2),(3/2) states including resolution of the property in the corresponding M{sub J} components. The polarizabilities are obtained by a numerical finite-field technique applying weak external electric fields. Special relativity is accounted for in the four-component Dirac framework. Two large-scale configuration interaction programs which can be applied either including or neglecting spin-dependent terms in the Dirac Hamiltonian, respectively, are used for the treatment of dynamic electron correlation. Coupled cluster calculations are performed for obtaining highly accurate J=(1/2) ground-state polarizabilities and for calibrating the configuration interaction calculations. The heavier atoms show large differences in the properties for different J states, and the effect of spin-orbit coupling is elucidated by separating it off from scalar relativistic contributions. The impact of spin-orbit interaction is also demonstrated for polarizability anisotropy components.
Independent Noise Can Synchronize Interacting Networks of Pulse-Coupled Oscillators
NASA Astrophysics Data System (ADS)
Riecke, Hermann; Meng, John
Structured networks comprised of subnetwork modules are ubiquitous. Motivated by the observation of rhythms and their interaction in different brain areas, we study a network consisting of two subnetworks of pulse-coupled integrate-fire neurons. Through mutual inhibition the neurons in the individual subnetworks can become synchronized and each subnetwork can exhibit coherent oscillatory dynamics, e.g. an ING-rhythm. In the absence of coupling between the networks the rhythms will in general have different frequencies. We investigate the interaction between these different rhythms. Strikingly, we find that increasing the noise level in the input to the individual neurons can synchronize the rhythms of the two networks, even though the inputs to different neurons are uncorrelated, sharing no common component. A heuristic phase model for the coupled networks shows that this synchronization hinges on the fact that only a fraction of the neurons may spike in a given cycle. Thus, the synchronization of the network rhythms differs qualitatively from that of individual oscillators. Supported by NSF-CMMI 1435358.
A Framework of Computing Multipolar Exchange Interactions in Systems with Strong Spin-Orbit Coupling
NASA Astrophysics Data System (ADS)
Pi, Shu-Ting
We intro duce a theoretical framework for computations of anisotropic multipolar exchange interactions found in many spin-orbit coupled magnetic systems and propose a method to extract these coupling constants using a density functional total energy calculation. This method is develop ed using a multipolar expansion of lo cal density matrices for correlated orbitals that are responsible for magnetic degrees of freedom. Within the mean-field approximation, we show that each coupling constant can b e recovered from a series of total energy calculations via what we call the "pair-flip" technique. This technique flips the relative phase of a pair of multipoles and computes the corresponding total energy cost associated with the given exchange constant. To test it, we apply our method to Uranium Dioxide, which is a system known to have pseudospin J = 1 superexchange induced dipolar, and superexchange plus spin-lattice induced quadrupolar orderings. Our calculation reveals that the superexchange and spin-lattice contributions to the quadrupolar exchange interactions are about the same order with ferro- and antiferro-magnetic contributions, respectively. This highlights a competition rather than a cooperation between them. Our method could be a promising tool to explore magnetic properties of rare-earth compounds and hidden-order materials.
Anisotropic multipolar exchange interactions in systems with strong spin-orbit coupling
NASA Astrophysics Data System (ADS)
Pi, Shu-Ting; Nanguneri, Ravindra; Savrasov, Sergey
2014-07-01
We introduce a theoretical framework for computations of anisotropic multipolar exchange interactions found in many spin-orbit coupled magnetic systems and propose a method to extract these coupling constants using a density functional total energy calculation. This method is developed using a multipolar expansion of local density matrices for correlated orbitals that are responsible for magnetic degrees of freedom. Within the mean-field approximation, we show that each coupling constant can be recovered from a series of total energy calculations via what we call the "pair-flip" technique. This technique flips the relative phase of a pair of multipoles and computes the corresponding total energy cost associated with the given exchange constant. To test it, we apply our method to uranium dioxide, which is a system known to have pseudospin J =1 superexchange induced dipolar, and superexchange plus spin-lattice induced quadrupolar orderings. Our calculation reveals that the superexchange and spin-lattice contributions to the quadrupolar exchange interactions are about the same order with ferro- and antiferromagnetic contributions, respectively. This highlights a competition rather than a cooperation between them. Our method could be a promising tool to explore magnetic properties of rare-earth compounds and hidden-order materials.
NASA Astrophysics Data System (ADS)
Mehdipour, M.; Shokrollahi, H.; Bahadoran, A.
2014-09-01
Ferromagnetic SrFe12O19-ZnFe2O4 nanostructure composite particles were synthesized by co-precipitation of chloride salts, in different stoichiometric ratios, by addition of sodium hydroxide solution. The resulting precursors were heat treated at temperatures in the range 800-1200°C for 4 h. Exchange interactions of the nanostructure composite particles were studied by use of exchange-coupling theory and plots of magnetic hysteresis. On the basis of exchange-coupling theory, the exchange interaction can be improved by increasing the soft phase content within the hard matrix. As temperature and soft phase ratio increase, the exchange interaction increases because of exchange length enhancement. The modified Brown's equation was also used to analyze the effects of exchange coupling on coercivity.
Novel effects of spin-orbit interaction in interacting electronic systems
NASA Astrophysics Data System (ADS)
Sun, Jianmin
Over the last several years there has been a remarkable growth in research activity in the physical properties of mesoscopic systems. Significant results, which were obtained by both theoretical and experimental studies, together with the enormous promise of nano-technology applications, contribute to this interest. In mesoscopic systems, there are 1023 or so electrons with strong Coulomb interaction. The length scale governing the electrons motion is small enough to cause quantization of the energy levels. In this work we study such quantum systems: quantum wires, quantum dots. During the last decade several experimental techniques have been developed for manufacturing both kinds of devices, which are currently an important tool for understanding low dimensions physics. The finite spin-orbit coupling is very natural, and, strictly speaking, unavoidable, in semiconducting quantum wires due to pronounced structural asymmetry inherent in the fabrication process. Thus the interplay between Coulomb interaction and spin-orbit coupling is important to investigate. The magnetic field also plays an important role which breaks the time-reversal symmetry of the Hamiltonian and splits the band of free electrons into two, corresponding to up-spin and down-spin electrons, reducing spin-rotational symmetry of the system from SU(2) to U(1). The dissertation takes account of the effect of the spin-orbit coupling interactions in the properties of mesoscopic systems. The manuscript is divided in four Chapters. In Chapter 1, the field theory in mesoscopic system is introduced. I present the relations between bosonic and fermionic operators in one dimension. These relations are used to bosonize spin 1/2 interaction fermion system. I show how to derive the RG equations around a fixed-point from the Operator Product Expansion (OPE). In Chapter 2, I present analysis of the interacting quantum wire problem in the presence of magnetic field and spin-orbital interaction. I show that an
Effects of Administered Alcohol on Intimate Partner Interactions in a Conflict Resolution Paradigm
Testa, Maria; Crane, Cory A.; Quigley, Brian M.; Levitt, Ash; Leonard, Kenneth E.
2014-01-01
Objective: Although couples’ alcohol use has been associated with intimate partner aggression and poorer marital functioning, few studies have examined the proximal effects of alcohol on couple interactions. The current experimental study examined the effects of alcohol, administered independently to male and female intimate partners, on positive and negative interaction behaviors within a naturalistic conflict resolution paradigm. Method: Married and cohabiting couples (n = 152) were recruited from the community and each partner randomly assigned to receive either alcohol (target dose: .08 mg/kg) or no alcohol. They engaged in two 15-minute interactions regarding current disagreements in their relationship, one before and one after beverage administration. Videotaped interactions were coded by trained observers using the Rapid Marital Interaction Coding System, and positive and negative interaction behaviors were analyzed using the Actor–Partner Interdependence Model. Results: Participants displayed decreased negativity and increased positivity following alcohol consumption when their partners were sober but no differences in negativity or positivity when their partners also consumed alcohol. There were no gender differences. Although participants with a history of perpetrating intimate partner aggression displayed more negativity, prior aggression did not interact with beverage condition. Conclusions: The immediate effects of alcohol consumption on couple interaction behaviors appeared more positive than negative. Contrary to hypotheses, congruent partner drinking had neither particularly positive nor particularly negative effects. These unique findings represent a rare glimpse into the immediate consequences of alcohol consumption on couple interaction and stand in contrast to its delayed or long-term effects. PMID:24650819
Effects of Nitrogen Fertilization on Tritrophic Interactions
Technology Transfer Automated Retrieval System (TEKTRAN)
Plant—herbivore—natural enemy interactions are basic components of nearly all ecosystems, and nitrogen can exert a variety of effects on plants which can significantly alter these interactions. We present a diagram illustrating the various ways that nitrogen can affect three trophic levels and revi...
Effects of Noise on Small Group Interaction.
ERIC Educational Resources Information Center
Whitehead, Jack L.
This study reports an analysis of the effects of moderate levels of noise on task performance of an interacting group. Groups of students first interacted in information-sharing discussions under varying conditions of noise and then responded to an objective test over the shared information and to a series of semantic differential scales designed…