The longest excursion of stochastic processes in nonequilibrium systems

We consider the excursions, i.e. the intervals between consecutive zeros, of stochastic processes that arise in a variety of nonequilibrium systems and study the temporal growth of the longest one l_{\max}(t) up to time t. For smooth processes, we find a universal linear growth \simeq Q_{\infty} t with a model dependent amplitude Q_\infty. In contrast, for non-smooth processes with a persistence exponent \theta, we show that < l_{\max}(t) > has a linear growth if \theta \sim t^{1-\psi} if \theta > \theta_c. The amplitude Q_{\infty} and the exponent \psi are novel quantities associated to nonequilibrium dynamics. These behaviors are obtained by exact analytical calculations for renewal and multiplicative processes and numerical simulations for other systems such as the coarsening dynamics in Ising model as well as the diffusion equation with random initial conditions.Comment: 4 pages,2 figure

The dynamics of bistable liquid crystal wells

A planar bistable liquid crystal device, reported in Tsakonas et al. [27], is modelled within the Landau-de Gennes theory for nematic liquid crystals. This planar device consists of an array of square micron-sized wells. We obtain six different classes of equilibrium profiles and these profiles are classified as diagonal or rotated solutions. In the strong anchoring case, we propose a Dirichlet boundary condition that mimics the experimentally imposed tangent boundary conditions. In the weak anchoring case, we present a suitable surface energy and study the multiplicity of solutions as a function of the anchoring strength. We find that diagonal solutions exist for all values of the anchoring strength W ≥ 0 while rotated solutions only exist for W ≥ Wc > 0, where Wc is a critical anchoring strength that has been computed numerically. We propose a dynamic model for the switching mechanisms based on only dielectric effects. For sufficiently strong external electric fields, we numerically demonstrate diagonal to rotated and rotated to diagonal switching by allowing for variable anchoring strength across the domain boundary

Dark Matter candidate in a Heavy Higgs Model - Direct Detection Rates

We investigate direct detection rates for Dark Matter candidates arise in a $SU(2)_L\times U(1)_Y$ with an additional doublet Higgs proposed by Barbieri, Hall and Rychkov. We refer this model as `Heavy Higgs Model'. The Standard Model Higgs mass comes out in this model very heavy adopting the few per cent chance that there is no Higgs boson mass below 200 GeV. The additional Higgs boson develops neither any VEV due to the choice of coefficient of the scalar potential of the model nor it has any coupling with fermions due to the incorporation of a discrete parity symmetry. Thus, the neutral components of the extra doublet are stable and can be considered as probable candidate of Cold Dark Matter. We have made calculations for three different types of Dark Matter experiments, namely, $^{76}$Ge (like GENIUS), DAMA (NaI) and XENON ($^{131}$Xe). Also demonstrated the annual variation of Dark Matter detection in case of all three detectors considered.Comment: 10 pages, 9 figures, figures unchanged, text modified, version to appear in Mod. Phys. Lett.

Singular Effect of Disorder on Electronic Transport in Strong Coupling Electron-Phonon Systems

We solve the disordered Holstein model in three dimensions considering the phonon variables to be classical. After mapping out the phases of the `clean' strong coupling problem, we focus on the effect of disorder at strong electron-phonon (EP) coupling. The presence of even weak disorder (i) enormously enhances the resistivity (\rho) at T=0, simultaneously suppressing the density of states at the Fermi level, (ii) suppresses the temperature dependent increase of \rho, and (iii) leads to a regime with d\rho/dT <0. We locate the origin of these anomalies in the disorder induced tendency towards polaron formation, and the associated suppression in effective carrier density and mobility. These results, explicitly at `metallic' density, are of direct relevance to disordered EP materials like covalent semiconductors, the manganites, and to anomalous transport in the A-15 compounds.Comment: Final versio

Impact of firm specific and macroeconomic factors on financial performance of the UAE insurance sector

This study analyses the impact of firm specific and macroeconomic factors on the profitability of the insurance sector in UAE during the period of 2009–2013. In the recent past, the global insurance sector was impacted by the ripple effect of the financial crisis of 2007–2008. Along the lines of the global trend, although profitability of the UAE, insurance sector witnessed a decline from 2008–2010, the spur in its growth rates (10%) in 2012 and 2013 is impressive compared to the negative growth rate in developed markets. Our research contributes to the existing body of knowledge on financial performance of the insurance sector post the global financial crisis. Our results indicate that within the firm specific factors; company size, growth in gross written premium (GWP), leverage, investment ratio and market share are statistically significant in explaining profitability of the insurance companies. Further, GDP growth has a significant positive influence on profitability