Symmetry breaking and manipulation of nonlinear optical modes in an asymmetric double-channel waveguide

We study light-beam propagation in a nonlinear coupler with an asymmetric double-channel waveguide and derive various analytical forms of optical modes. The results show that the symmetry-preserving modes in a symmetric double-channel waveguide are deformed due to the asymmetry of the two-channel waveguide, yet such a coupler supports the symmetry-breaking modes. The dispersion relations reveal that the system with self-focusing nonlinear response supports the degenerate modes, while for self-defocusingmedium the degenerate modes do not exist. Furthermore, nonlinear manipulation is investigated by launching optical modes supported in double-channel waveguide into a nonlinear uniform medium.Comment: 10 page

A hybrid stabilization technique for simulating water wave - Structure interaction by incompressible Smoothed Particle Hydrodynamics (ISPH) method

The Smoothed Particle Hydrodynamics (SPH) method is emerging as a potential tool for studying water wave related problems, especially for violent free surface flow and large deformation problems. The incompressible SPH (ISPH) computations have been found not to be able to maintain the stability in certain situations and there exist some spurious oscillations in the pressure time history, which is similar to the weakly compressible SPH (WCSPH). One main cause of this problem is related to the non-uniform and clustered distribution of the moving particles. In order to improve the model performance, the paper proposed an efficient hybrid numerical technique aiming to correct the ill particle distributions. The correction approach is realized through the combination of particle shifting and pressure gradient improvement. The advantages of the proposed hybrid technique in improving ISPH calculations are demonstrated through several applications that include solitary wave impact on a slope or overtopping a seawall, and regular wave slamming on the subface of open-piled structure

Achieving new product success via the synchronization of exploration and exploitation across multiple levels and functional areas

While ambidexterity has been identified as a critical prerequisite for new product success, synchronizing exploration and exploitation in practice represents a multifaceted enigma. Ambidexterity is not in reality limited to a single organizational level, or a specific functional area. Firms become ambidextrous when corporate-level exploratory and exploitative strategies interact with operational-level exploratory and exploitative capabilities across multiple functional areas. Data from a sample of technology-intensive industrial firms using a multi-informant design shows that operational-level exploratory and exploitative product innovation and marketing capabilities allow firms to implement corporate-level exploratory and exploitative strategies in the context of new product development (NPD). Further, the findings reveal that the integration of exploratory product innovation–exploratory marketing and exploitative product innovation–exploitative marketing is significant for the implementation of exploratory and exploitative strategies over deploying each capability in isolation. Finally, we show that the implementation of exploratory and exploitative strategies drives new product success through creating distinct positional advantages to customers in the form of both differentiation and cost efficiency. These positional advantages help to better explain the effects of exploratory and exploitative capabilities on new product market performance.11 page(s

Phonon arithmetic in a trapped ion system

Single-quantum level operations are important tools to manipulate a quantum state. Annihilation or creation of single particles translates a quantum state to another by adding or subtracting a particle, depending on how many are already in the given state. The operations are probabilistic and the success rate has yet been low in their experimental realization. Here we experimentally demonstrate (near) deterministic addition and subtraction of a bosonic particle, in particular a phonon of ionic motion in a harmonic potential. We realize the operations by coupling phonons to an auxiliary two-level system and applying transitionless adiabatic passage. We show handy repetition of the operations on various initial states and demonstrate by the reconstruction of the density matrices that the operations preserve coherences. We observe the transformation of a classical state to a highly non-classical one and a Gaussian state to a non-Gaussian one by applying a sequence of operations deterministically

Raman scattering study of (Kx_xSr1−x_{1-x})Fe2_2As2_2 (xx = 0.0, 0.4)

Polarized Raman spectra of non-superconducting SrFe$_2$As$_2$ and superconducting K$_{0.4}$Sr$_{0.6}$Fe$_2$As$_2$ ($T_c = 37$ K) are reported. All four phonon modes (A$_{1g}$ + B$_{1g}$ + 2E$_g$) allowed by symmetry, are found and identified. Shell model gives reasonable description of the spectra. No detectable anomalies are observed near the tetragonal-to-orthorhombic transition in SrFe$_2$As$_2$ or the superconducting transition in K$_{0.4}$Sr$_{0.6}$Fe$_2$As$_2$.Comment: 4 pages, 4 figures, 2 table

The Activity of Spontaneous Action Potentials in Developing Hair Cells Is Regulated by Ca2+-Dependence of a Transient K+ Current

Spontaneous action potentials have been described in developing sensory systems. These rhythmic activities may have instructional roles for the functional development of synaptic connections. The importance of spontaneous action potentials in the developing auditory system is underpinned by the stark correlation between the time of auditory system functional maturity, and the cessation of spontaneous action potentials. A prominent K+ current that regulates patterning of action potentials is IA. This current undergoes marked changes in expression during chicken hair cell development. Although the properties of IA are not normally classified as Ca2+-dependent, we demonstrate that throughout the development of chicken hair cells, IA is greatly reduced by acute alterations of intracellular Ca2+. As determinants of spike timing and firing frequency, intracellular Ca2+ buffers shift the activation and inactivation properties of the current to more positive potentials. Our findings provide evidence to demonstrate that the kinetics and functional expression of IA are tightly regulated by intracellular Ca2+. Such feedback mechanism between the functional expression of IA and intracellular Ca2+ may shape the activity of spontaneous action potentials, thus potentially sculpting synaptic connections in an activity-dependent manner in the developing cochlea

Averaging approximation to singularly perturbed nonlinear stochastic wave equations

An averaging method is applied to derive effective approximation to the following singularly perturbed nonlinear stochastic damped wave equation \nu u_{tt}+u_t=\D u+f(u)+\nu^\alpha\dot{W} on an open bounded domain $D\subset\R^n$\,, $1\leq n\leq 3$\,. Here $\nu>0$ is a small parameter characterising the singular perturbation, and $\nu^\alpha$\,, $0\leq \alpha\leq 1/2$\,, parametrises the strength of the noise. Some scaling transformations and the martingale representation theorem yield the following effective approximation for small $\nu$, u_t=\D u+f(u)+\nu^\alpha\dot{W} to an error of \ord{\nu^\alpha}\,.Comment: 16 pages. Submitte