Periodically Aligned Liquid Crystal: Potential application for projection displays

A nematic liquid crystal (NLC) layer with the anisotropy axis modulated at a fixed rate q in the transverse direction is considered. If the layer locally constitutes a half-wave plate, then the thin-screen approximation predicts 100% -efficient diffraction of normal incident wave. The possibility of implementing such a layer via anchoring at both surfaces of a cell with thickness L is studied as a function of parameter qL and threshold values of this parameter are found for a variety of cases. Distortions of the structure of director in comparison with the preferable ideal profile are found via numerical modeling. Freedericksz transition is studied for this configuration. Coupled-mode theory is applied to light propagation through such cell allowing to account for walk-off effects and effects of nematic distortion. In summary, this cell is suggested as a means for projection display; high efficiency is predicted.Comment: 25 pages, 6 figures, 1 tabl

Rich variety of defects in ZnO via an attractive interaction between O-vacancies and Zn-interstitials

As the concentration of intrinsic defects becomes sufficiently high in O-deficient ZnO, interactions between defects lead to a significant reduction in their formation energies. We show that the formation of both O-vacancies and Zn-interstitials becomes significantly enhanced by a strong attractive interaction between them, making these defects an important source of n-type conductivity in ZnO.Comment: 12 pages, 4 figure

Pure spinor computation towards open string three-loop

Using the recent results in the pure spinor formulation, we lay out a ground-work towards the full momentum space amplitudes of open superstrings at three-loop. After briefly reviewing the one-loop amplitude, we directly work out the two-loop and reproduce the result that was obtained by a symmetry argument. For the three-loop, first we use the two-loop regulator as a warm-up exercise. The result vanishes. We then employ the regulator that has been recently proposed by Aisaka and Berkovits (AB). It is noted that the terms in higher power in $\frac{1}{\lambda\bar{\lambda}}$ that render the two-loop regulator disqualified for the three-loop do not contribute. This with a few other indications suggests a possibility that the AB regulator might also lead to a vanishing result. Nevertheless, we argue that it is possible to acquire the three-loop amplitude, and present a result that we anticipate to be the three-loop amplitude.Comment: 41 pages, latex, cosmetic change

Dynamic behavior of driven interfaces in models with two absorbing states

We study the dynamics of an interface (active domain) between different absorbing regions in models with two absorbing states in one dimension; probabilistic cellular automata models and interacting monomer-dimer models. These models exhibit a continuous transition from an active phase into an absorbing phase, which belongs to the directed Ising (DI) universality class. In the active phase, the interface spreads ballistically into the absorbing regions and the interface width diverges linearly in time. Approaching the critical point, the spreading velocity of the interface vanishes algebraically with a DI critical exponent. Introducing a symmetry-breaking field $h$ that prefers one absorbing state over the other drives the interface to move asymmetrically toward the unpreferred absorbing region. In Monte Carlo simulations, we find that the spreading velocity of this driven interface shows a discontinuous jump at criticality. We explain that this unusual behavior is due to a finite relaxation time in the absorbing phase. The crossover behavior from the symmetric case (DI class) to the asymmetric case (directed percolation class) is also studied. We find the scaling dimension of the symmetry-breaking field $y_h = 1.21(5)$.Comment: 5 pages, 5 figures, Revte

Sine-Gordon Soliton on a Cnoidal Wave Background

The method of Darboux transformation, which is applied on cnoidal wave solutions of the sine-Gordon equation, gives solitons moving on a cnoidal wave background. Interesting characteristics of the solution, i.e., the velocity of solitons and the shift of crests of cnoidal waves along a soliton, are calculated. Solutions are classified into three types (Type-1A, Type-1B, Type-2) according to their apparent distinct properties.Comment: 11 pages, 5 figures, Contents change

Local spectroscopy of a proximity superconductor at very low temperature

We performed the local spectroscopy of a Normal-metal--Superconductor (N-S) junction with the help of a very low temperature (60 mK) Scanning Tunneling Microscope (STM). The spatial dependence of the local density of states was probed locally in the vicinity of the N-S interface. We observed spectra with a fully-developed gap in the regions where a thin normal metal layer caps the superconductor dot. Close to the S metal edge, a clear pseudo-gap shows up, which is characteristic of the superconducting proximity effect in the case of a long normal metal. The experimental results are compared to the predictions of the quasiclassical theory.Comment: 7 pages, 3 figure

Massive super Yang-Mills quantum mechanics: classification and the relation to supermembrane

We classify the supersymmetric mass deformations of all the super Yang-Mills quantum mechanics, which are obtained by dimensional reductions of minimal super Yang-Mills in spacetime dimensions: ten, six, four, three and two. The resulting actions can be viewed as the matrix descriptions of supermembranes in nontrivial backgrounds of one higher dimensional supergravity theories. We also discuss the utmost generalization of the light-cone formulation of the Nambu-Goto action for a p-brane, including time dependent backgrounds

Use of Energy in Data-Track Association and State Estimation in Multitarget-Multisensor Problems

A coarse test and a fine test have been formulated for use in multiple sensor-multiple target data-track association. Various forms of energies are used in these tests to pick the proper data to be associated with any target. Numerical experiments which involve the use of a decentralized Kalman filter scheme are presented. The experiments show the effectiveness of the two test

Evaluation of superalloy heavy-duty grinding based on multivariate tests

The quality and economy of grinding depend on proper selection of grinding conditions for the materials to be ground. In order to evaluate the effect of heavy-duty grinding, a new performance index, which includes specific material removal rate, size accuracy, and grinding forces, was proposed. Robust design of experiment, including orthogonal arrays, the signal-to-noise ratio (SNR) method, and analysis of variance (ANOVA) for multivariate data, was employed to estimate the effect of uniform experimental design and to optimize grinding parameters. Empirical models of grinding force were investigated for finite element analysis of new fixture design. These empirical models, based on robust design of experiments and multiple regression methodology, have been confirmed through further verification experiments. Correlation coefficients from 0.87 to 0.96 were achieved