Relative Coupling Strength Research Articles

Search-Based Object-Oriented Software Re-Structuring with Structural Coupling Strength

Abstract In real world, the software systems often need to be continuously modified to satisfy the ever changing requirements and environment. Mostly, it is carried out without following the original design principles of the system. Over a period of time, such a continuous modification deteriorates the structural quality, hence increases the system complexity. To improve the structural quality of whole system, the software clustering seems more feasible technique. Recently, the search – based approach gain more attention to solve the software clustering problem. In this paper, we propose a search – based multi – objective optimization to re-structure the object – oriented software system using different coupling strength scheme such as binary coupling, absolute coupling and relative coupling scheme. The approach is evaluated over four real – world and three random software applications. The experimentation results show that how the use of absolute and relative coupling strength scheme leads to generate more effective solutions compared binary coupling strength.

Imaging Josephson vortices on the surface superconductor Si(111)-(√7×√3)-In using a scanning tunneling microscope.

We have studied the superconducting Si(111)-(√7×√3)-In surface using a ³He-based low-temperature scanning tunneling microscope. Zero-bias conductance images taken over a large surface area reveal that vortices are trapped at atomic steps after magnetic fields are applied. The crossover behavior from Pearl to Josephson vortices is clearly identified from their elongated shapes along the steps and significant recovery of superconductivity within the cores. Our numerical calculations combined with experiments clarify that these characteristic features are determined by the relative strength of the interterrace Josephson coupling at the atomic step.

Designing frequency-dependent relaxation rates and Lamb shifts for a giant artificial atom

In traditional quantum optics, where the interaction between atoms and light at optical frequencies is studied, the atoms can be approximated as point-like when compared to the wavelength of light. So far, this relation has also been true for artificial atoms made out of superconducting circuits or quantum dots, interacting with microwave radiation. However, recent and ongoing experiments using surface acoustic waves show that a single artificial atom can be coupled to a bosonic field at several points wavelengths apart. Here, we theoretically study this type of system. We find that the multiple coupling points give rise to a frequency dependence in the coupling strength between the atom and its environment, and also in the Lamb shift of the atom. The frequency dependence is given by the discrete Fourier transform of the coupling point coordinates and can therefore be designed. We discuss a number of possible applications for this phenomenon, including tunable coupling, single-atom lasing, and other effects that can be achieved by designing the relative coupling strengths of different transitions in a multi-level atom.

Coherently induced shifting of group index across the triple atomic transition lines in Double-N-type system

The group index and its corresponding absorption of a propagating probe pulse across three atomic transition lines is theoretically presented for a Double-N-type non-EIT scheme. We have shown that, group index on the three transition lines can be shifted accordingly to control the status (superluminal/subluminal) of the pulse propagation with reduced absorption/gain by controlling the relative strength of coherent coupling. The analytical expression of effective detuning clearly exhibits the nature of linear AC Stark shift responsible for shifting/switching of group index on three different probe transition frequency regimes.

Recent Progress in Tau Lepton Physics

The τ lepton is the heaviest of the charged leptons and the only one to decay into hadrons. This provides a unique opportunity to probe low energy QCD and the charged weak interaction of both the relative coupling strength to the first and second generation of quarks and to the lepton. Moreover, many new physics scenarios couple primarily to the third generation, making it a promising prospect for new physics searches. In this paper, an overview of recent measurements of the τ lepton from BABAR , BELLE and BES are presented.

Equi-Reflectance Dual Mode Resonance Using Bimetallic Loaded Dielectric Plasmonic Structure

Theoretical study of the reflectance response of an asymmetrically-clad bimetallic film that supports coupled surface plasmon polariton modes has been presented. Through adjusting the relative thickness of the two metal film components, the relative coupling strength to the long range (LR) and short range plasmon modes can be altered. It is possible to obtain optimal and equi coupling (zero reflectivity) to both modes for given incident wavelength by further adjusting the overall thickness of bimetallic film. Simultaneous angular and spectral sensitivity calculations of resonance of the LR mode have been demonstrated for sensing application. Tailoring of the structure of individual metal films realizing equi- and non-equi-reflectance modes has been proposed which may further be used for plasmonic trinary logic using binary di-bit images.

Temporal Coupling Is More Robust Than Spatial Coupling: An Investigation of Interlimb Coordination After Stroke

ABSTRACT Interlimb coordination obtained through temporal and spatial coupling is a significant feature of human motor control. To understand the robustness of this capability the authors introduced a method to quantify interlimb coordination strength and compare individuals with asymmetric effector ability poststroke to nondisabled controls. Quantitative analyses determined the relative strength of interlimb coupling with an asymmetric obstacle avoidance task. Participants performed bimanual discrete, multijoint aiming movements in the frontal plane with a vertical barrier positioned midway to the target for one limb. To quantify coupling strength between limbs and groups, we regressed individual participant nonbarrier limb movement time or maximum vertical displacement separately, on barrier limb performance. Temporal and spatial interlimb coupling strength varied across participants in both groups. Barrier limb performance predicted nonbarrier limb behavior; however, interlimb coupling was significantly stronger for the nondisabled compared to the stroke group. In the stroke group, deficits in interlimb coordination affected spatial coupling more than temporal coupling. The decreased coupling strength detected, even in the presence of mild hemiparesis, demonstrates the measure's sensitivity. The authors propose this metric as a powerful assessment of the effectiveness of rehabilitation interventions and to monitor the recovery of bimanual coordination poststroke.

A Compact Coupling Controllable Elliptical Filter Based on Multilayer LTCC

This paper presents a compact elliptical filter based on modified λ/4 resonators with separated electric and magnetic coupling paths. For the proposed second-order filters, transmission zero points are generated at either lower or upper stopband by controlling the relative coupling strength in the two paths of inter-stage resonators. Based on the topology and multilayer LTCC technology, a fourth-order bandpass filters operating at 5.2 GHz with a fractional bandwidth of 10% in 1.7 mm × 3 mm (0.0785λg × 0.1385λg) is designed and verified experimentally. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1789–1792, 2013

Shock transmission in a coupled beam system

This paper investigates the circumstances under which high peak acceleration can occur in the internal parts of a system when subjected to impulsive driving on the outside. Motivating examples include the design of packaging for transportation of fragile items. The system is modelled in an idealised form using two beams coupled with point connections. A Rayleigh–Ritz model of such coupled beams was validated against measurements on a particular beam system, then the model was used to explore the acceleration response to impulsive driving in the time, frequency and spatial domains. This study is restricted to linear vibration response and additional mechanisms for high internal acceleration due to nonlinear effects such as internal impacts are not considered. Using Monte Carlo simulation in which the indirectly driven beam was perturbed by randomly placed point masses a wide range of system behaviour was explored. This facilitates identification of vulnerable configurations that can lead to high internal acceleration. The results from the study indicate the possibility of curve veering influencing the peak acceleration amplification. The possibility of veering within an ensemble was found to be dependent on the relative coupling strength of the modes. Understanding of the mechanism may help to avoid vulnerable cases, either by design or by preparatory vibration testing.

Creation of quantum correlations via the initial classical-mixed states

Using the pseudomode method, we theoretically analyze the creation of quantum correlations between two two-level dipole—dipole interacting atoms coupled with a common structured reservoir with different coupling strengths. Considering certain classes of initial separable-mixed states, we demonstrate that the sudden birth of atomic entanglement as well as the generation of stationary quantum correlations occur. Our results also suggest a possible way to control the occurrence time of entanglement sudden birth and the stationary value of quantum correlations by modifying the initial conditions of states, the dipole—dipole interaction, and the relative coupling strength. These results are helpful for the experimental engineering of entanglement and quantum correlations.

Chiral-Symmetry-Violating Effects and Near-Maximal Mixing of Scalar Gluonium and Quark Mesons

Gaussian QCD sum-rules are used to analyze all possible two-point correlation functions of scalar gluonic and quark currents. The independent predictions of the masses and relative coupling strengths from the different correlators are remarkably consistent with a scenario of two scalar states that couple to nearly-maximal mixtures of quark and gluonic currents.

Understanding photosynthetic light-harvesting: a bottom up theoretical approach

We discuss a bottom up approach for modeling photosynthetic light-harvesting. Methods are reviewed for a full structure-based parameterization of the Hamiltonian of pigment-protein complexes (PPCs). These parameters comprise (i) the local transition energies of the pigments in their binding sites in the protein, the site energies; (ii) the couplings between optical transitions of the pigments, the excitonic couplings; and (iii) the spectral density characterizing the dynamic modulation of pigment transition energies and excitonic couplings by protein vibrations. Starting with quantum mechanics perturbation theory, we provide a microscopic foundation for the standard PPC Hamiltonian and relate the expressions obtained for its matrix elements to quantities that can be calculated with classical molecular mechanics/electrostatics approaches including the whole PPC in atomic detail and using charge and transition densities obtained with quantum chemical calculations on the isolated building blocks of the PPC. In the second part of this perspective, the Hamiltonian is utilized to describe the quantum dynamics of excitons. Situations are discussed that differ in the relative strength of excitonic and exciton-vibrational coupling. The predictive power of the approaches is demonstrated in application to different PPCs, and challenges for future work are outlined.

Disorder, Cluster Spin Glass, and Hourglass Spectra in Striped Magnetic Insulators

Hourglass-shaped magnetic excitation spectra have been detected in a variety of doped transition-metal oxides with stripelike charge order. Compared to the predictions of spin-wave theory for perfect stripes, these spectra display a different intensity distribution and anomalous broadening. Here we show, based on a comprehensive modeling for La5/3Sr1/3CoO4, how quenched disorder in the charge sector causes frustration, and consequently cluster-glass behavior at low temperatures, in the spin sector. This spin-glass physics, which is insensitive to the detailed nature of the charge disorder, but sensitive to the relative strength of the magnetic interstripe coupling, ultimately determines the distribution of magnetic spectral weight: The excitation spectrum, calculated using spin waves in finite disordered systems, is found to match in detail the observed hour-glass spectrum.

Challenges for the Accurate Simulation of Anisotropic Charge Mobilities through Organic Molecular Crystals: The β Phase of mer-Tris(8-hydroxyquinolinato)aluminum(III) (Alq3) Crystal

Quantitative agreement has been found between observed and calculated charge mobilities through organic conductors, despite the use of many assumptions in the calculations, including: the relative strength of the intermolecular electronic coupling to the reorganization energy driving charge localization, the treatment of site variability in the material, the involvement of tunneling processes during charge hopping between sites, the use of weak-coupling-based perturbation theory to determine hopping rates, the residence times for charges on sites, the effect of the large field strengths used in experimental studies, the general appropriateness of simple one-dimensional diffusion modeling approaches, and the involvement of molecular excited states of the ions. We investigate the impact of these assumptions, concluding that all may be very significant. In some cases, methodological options are considered, and optimum procedures are determined, showing that (i) the use of Koopmans' theorem to estimate intermolecular couplings in solids is problematic and (ii) the correct expression for the residence lifetime of a charge on a crystal site. These conclusions are drawn from simulations of anisotropic charge mobilities through the β phase of mer-tris(8-hydroxyquinolinato)aluminum(III) (Alq3) crystal, a material commonly used in OLED applications. Calculations are compared that determine mobilities at finite applied field from drift velocities through either semianalytical solutions of the master equation or else kinetic Monte Carlo simulations, as well as those that determine mobilities from multidimensional diffusion coefficients at zero field by Monte Carlo and those that analytically solve simplified one-dimensional diffusion models. For crystalline Alq3 itself, the calculations predict electron mobilities that are 4–6 orders of magnitude larger than those predicted by similar methods for amorphous Alq3, in agreement with experimental findings. This work vindicates recent theories describing the poor mobilities of the amorphous material, forming a complete basic picture for Alq3 conductivity.

Predictability of dry season reforecasts over the tropical and the sub‐tropical South American region

AbstractIn this study, we diagnose the fidelity of South American dry season (June–July–August) reforecasts from a global climate model (GCM) and a regional climate model (RCM). This includes a set of downscaled integrations of the RCM that uses a bias correction method called anomaly nesting, which is designed to remove the bias of the GCM that forces the RCM at the lateral boundaries. The models are integrated for seven dry seasons (2001–2007), and each season consists of six ensemble members. For this study, we focus on two primary regions: the Amazon River Basin (ARB) and the subtropical (ST) region.The paper discusses the regions of model bias for 2 m air temperature and for precipitation within ARB and ST regions first using corresponding independent observations and then with the NCEP Climate Forecast System Reanalysis (CFSR). The paper also dwells on the predictability of the above normal, normal and below normal occurrences of the two variables using signal‐to‐noise ratios and calculation of the area under the relative operative characteristic (ROC) curve (AUC). The models produced the largest biases of both variables over elevated terrain and within the intertropical convergence zone (ITCZ). Signal‐to‐noise ratios show that the models exhibit more predictability in ARB than they do in ST and that there is more predictability for surface air temperature than for precipitation. AUCs confirm that temperature is more skilfully predicted than precipitation and that the models exhibit more skill in ARB than in ST. AUCs also show that the anomaly nesting integrations have a limited advantage over the rest with some modest improvements in skill of surface temperature prediction over ARB.Lastly, we evaluate how the three models depict land‐atmosphere interactions during the dry season and compare their results with CFSR. We find conflicting results between the global and regional model predictions and CFSR on the relative coupling strength between the land and the atmosphere during the dry season. Copyright © 2012 Royal Meteorological Society

Hierarchical synchrony of phase oscillators in modular networks

We study synchronization of sinusoidally coupled phase oscillators on networks with modular structure and a large number of oscillators in each community. Of particular interest is the hierarchy of local and global synchrony, i.e., synchrony within and between communities, respectively. Using the recent ansatz of Ott and Antonsen [Chaos 18, 037113 (2008)], we find that the degree of local synchrony can be determined from a set of coupled low-dimensional equations. If the number of communities in the network is large, a low-dimensional description of global synchrony can be also found. Using these results, we study bifurcations between different types of synchrony. We find that, depending on the relative strength of local and global coupling, the transition to synchrony in the network can be mediated by local or global effects.

Theory of ac Stark splitting in core-resonant Auger decay in strong x-ray fields

In this work we report the modification of the normal Auger line shape under the action of an intense x-ray radiation. Under strong Rabi-type coupling of the core, the Auger line profile develops into a doublet structure with an energy separation mainly determined by the relative strength of the Rabi coupling. In addition, we find that the charge resolved ion yields can be controlled by judicious choice of the x-ray frequency.

The magnetic proximity effect in a ferrimagnetic Fe3O4 core/ferrimagnetic γ-Mn2O3 shell nanoparticle system

We report the magnetic proximity effect in a ferrimagnetic Fe3O4 core/ferrimagnetic γ-Mn2O3 shell nanoparticle system, in terms of an enhancement of the Curie temperature (Tc) of the γ-Mn2O3 shell (∼66 K) compared to its bulk value (∼40 K), and the presence of magnetic ordering in its so-called paramagnetic region (i.e. above 66 K). The ferrimagnetic nature of both core and shell has been found from a neutron diffraction study. The origin of these two features of the magnetic proximity effect has been ascribed to the proximity of the γ-Mn2O3 shell with a high-Tc Fe3O4 core (∼858 K in bulk form) and an interface exchange coupling between core and shell. Interestingly, we did not observe any exchange bias effect, which has been interpreted as a signature of a weak interface exchange coupling between core and shell. The present study brings out the importance of the relative strength of the interface coupling in governing the simultaneous occurrence of the magnetic proximity effect and the exchange bias phenomenon in a single system.

On the magnetic coupling in asymmetric bridged Cu(II) dinuclear complexes: The influence of substitutions on the carboxylato group

A quantum chemical study is presented of the magnetic coupling in a series of Cu(II) dinuclear complexes with an asymmetric double bridge formed by a μ-carboxylato- and a μ-alkoxo ligand. The complexes have different substituents on the carboxylato group and show non-intuitive relative magnetic coupling strengths. We address the influence of the substituents and establish the relative importance of the two bridges for the magnetic coupling. Moreover, we give a quantitative estimate of the complementarity effect of the two ligands. Finally, the study of the magneto-structural correlations show that the angle between the planes formed by the atoms surrounding the Cu(II) atoms is the determining factor to explain the differences in the magnetic coupling observed in the complexes and that the electronic effect of the substituents is negligible.

Oceanographic coupling across three trophic levels shapes source–sink dynamics in marine metacommunities

A central goal of metapopulation ecology is to determine which subpopulations have the greatest value to the larger metapopulation. That is, where are the ‘sources’ that are most essential to persistence? This question is especially relevant to benthic marine systems, where dispersal and recruitment are greatly affected by oceanographic processes. In a single‐species context, theoretical models typically identify ‘hotspots’ with high recruitment, especially high self‐recruitment, as having the highest value. However, the oceanographic forces affecting larval delivery of a given species may also influence the recruitment of that species’ predators, prey, and competitors.We present evidence from the Virgin Islands and Bahamas that oceanographic forces produce spatial coupling between the recruitment of planktivorous fishes, the recruitment of their predators, and the productivity of their zooplankton prey. We examined the consequences of this type of multi‐trophic coupling using a simple analytical population model and a multispecies numerical simulation model with parameter values based on the Virgin Islands system. In both analyses, strong coupling caused planktivores at the highest recruitment sites to experience higher mortality (a consequence of higher predator densities) but faster growth and higher fecundity (a consequence of higher zooplankton densities) than planktivores at low recruitment sites. As such, the relative strength of oceanographic coupling between the three trophic levels strongly determined whether a particular reef acted as a source or sink. In the simulation model, density‐dependent competition for zooplankton limited overall metapopulation biomass more severely than predation, so oceanographic coupling between planktivore larval supply and zooplankton productivity had a stronger effect on the metapopulation value of a patch. We argue that the potential for such tri‐trophic coupling should be incorporated into future metacommunity models and has considerable implications for the design and evaluation of marine reserves.