Speed of Processing: Tests and Factor Structure

In the present study we examined Speed of Processing derived from a number of cognitive tests; the response speeds were nearly automatic for tests with minimal cognitive load. The tests were given to students across ages from 8 to 20 in schools and colleges located in various parts of India. The structure of the constellation of the test responses was determined by factor analyses. We report one stable factor of speed for ages 8-10 that splits into two separate but correlated factors for ages 11-14,15-17, and 18-20 representing speed of response to tests that contain letters and numbers versus colour stimuli. Developmental changes in response speed across the four adjacent age groups were examined; the trajectory was not consistently incremental, especially for naming colours that did not increase beyond age 11-14.In conclusion, a fairly reasonable deconstruction of the concepts  of RAN has been presented in this report. The major components are  encoding and articulation, and the necessity  of distinguishing alpha-numeric naming time  and colour naming. The later requires the additional time for semantic access. At the end, we suggest that in a follow-up research RAN(alpha-numeric&colour) should be viewed as a part of a broader cognitive speed of processing.Our objective is to determine the association between tests of basic executive processes such as cognitive flexibility,attention &inhibition and working memory on the one hand and speed on the other.Consequently not to search for the tests that would  not involve speed, but be aware of the value of  the correlation of an executive  test with sp eed.This will be useful information or example in investigations into the effect of ageing on executive functions. A worthy agenda for future research. Keywords: Rapid Automatic Naming(RAN),Developmental Changes, Executive Functions DOI: 10.7176/JEP/13-30-11 Publication date:October 31st 202

Neutron scattering as a probe for unconventional superconducting states

We show that in the unconventional pairing state of a superconductor, i.e., the state with nodes in its excitation spectrum, the dynamical structure factor S(q,) has anomalous resonance peaks in q space. These resonance peaks are due to quasiparticle scattering between different nodes on the Fermi surface. The symmetry of the order parameter and the Fermi-surface geometry uniquely determine the resonance pattern. Observation of such peaks by neutron scattering will unambiguously determine the symmetry of the superconducting pairing state. Quantitative calculations are carried out in two dimensions to demonstrate this unusual effect. Applications to high-Tc oxide superconductors are discussed

Effects of substrate curvature radius, deposition temperature and coating thickness on the residual stress field of cylindrical thermal barrier coatings

In a thermal barrier coating (TBC) system with cylindrical geometry, the position of coating plays an important role in the distribution of residual stress. In this paper, the residual stress field in three different types of TBCs with cylindrical geometry has been analyzed. The main focus is on the effects of substrate curvature radius, deposition temperature and coating thickness on the residual stress distribution during a deposition process. The results show that the substrate curvature radius significantly affects the distributions of radial and hoop residual stresses, which are in good agreement with experimental measurements by photo-stimulated luminescence piezospectroscopy (Wang et al., Acta Mater., 2009, 57(1):182–195). The maximum radial residual stress locates closely to the coating/thermal grown oxide interface. However, the maximum hoop residual stress lies in the thermal grown oxide layer, which is much more than other three layers and presents a strong stress singularity along the thickness direction

Liquid-Gas Coexistence and Critical Behavior in Boxed Pseudo-Fermi Matter

A schematic model is presented that allows one to study the behavior of interacting pseudo-Fermi matter locked in a thermostatic box. As a function of the box volume and temperature, the matter is seen to show all of the familiar charactersitics of a Van der Waals gas, which include the coexistence of two phases under certain circumstances and the presence of a critical point

The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. II. Theoretical Model

The observed powerlaw distributions of solar flare parameters can be interpreted in terms of a nonlinear dissipative system in the state of self-organized criticality (SOC). We present a universal analytical model of a SOC process that is governed by three conditions: (i) a multiplicative or exponential growth phase, (ii) a randomly interrupted termination of the growth phase, and (iii) a linear decay phase. This basic concept approximately reproduces the observed frequency distributions. We generalize it to a randomized exponential-growth model, which includes also a (log-normal) distribution of threshold energies before the instability starts, as well as randomized decay times, which can reproduce both the observed occurrence frequency distributions and the scatter of correlated parametyers more realistically. With this analytical model we can efficiently perform Monte-Carlo simulations of frequency distributions and parameter correlations of SOC processes, which are simpler and faster than the iterative simulations of cellular automaton models. Solar cycle modulations of the powerlaw slopes of flare frequency distributions can be used to diagnose the thresholds and growth rates of magnetic instabilities responsible for solar flares.Comment: Part II of Paper I: The State of Self-Organized Criticality of the Sun During the Last Three Solar Cycles. I. Observation

Nanotube Piezoelectricity

We combine ab initio, tight-binding methods and analytical theory to study piezoelectric effect of boron nitride nanotubes. We find that piezoelectricity of a heteropolar nanotube depends on its chirality and diameter and can be understood starting from the piezoelectric response of an isolated planar sheet, along with a structure specific mapping from the sheet onto the tube surface. We demonstrate that coupling between the uniaxial and shear deformation are only allowed in the nanotubes with lower chiral symmetry. Our study shows that piezoelectricity of nanotubes is fundamentally different from its counterpart in three dimensional (3D) bulk materials.Comment: 4 pages, with 3 postscript figures embedded. Uses REVTEX4 macros. Also available at http://www.physics.upenn.edu/~nsai/preprints/bn_piezo/index.htm

Impurity state in Haldane gap for S=1 Heisenberg antiferromagnetic chain with bond doping

Using a new impurity density matrix renormalization group scheme, we establish a reliable picture of how the low lying energy levels of a $S=1$ Heisenberg antiferromagnetic chain change {\it quantitatively} upon bond doping. A new impurity state gradually occurs in the Haldane gap as $J' < J$, while it appears only if $J'/J>\gamma_c$ with $1/\gamma_c=0.708$ as $J'>J$. The system is non-perturbative as $1\leq J'/J\leq\gamma_c$. This explains the appearance of a new state in the Haldane gap in a recent experiment on Y$_{2-x}$Ca$_x$BaNiO$_5$ [J.F. DiTusa, et al., Phys. Rev. Lett. 73 1857(1994)].Comment: 4 pages of uuencoded gzip'd postscrip

Impurity Energy Level Within The Haldane Gap

An impurity bond $J{'}$ in a periodic 1D antiferromagnetic, spin 1 chain with exchange $J$ is considered. Using the numerical density matrix renormalization group method, we find an impurity energy level in the Haldane gap, corresponding to a bound state near the impurity bond. When $J{'}<J$ the level changes gradually from the edge of the Haldane gap to the ground state energy as the deviation $dev=(J-J{'})/J$ changes from 0 to 1. It seems that there is no threshold. Yet, there is a threshold when $J{'}>J$. The impurity level appears only when the deviation $dev=(J{'}-J)/J{'}$ is greater than $B_{c}$, which is near 0.3 in our calculation.Comment: Latex file,9 pages uuencoded compressed postscript including 4 figure

Mistakes in quasilattices

We studied a class of mistakes or faults in quasilattices. The effect of a random distribution of mistakes on the diffraction of 1D, and a special class of 3D, quasilattices is calculated exactly. Mistakes change the diffraction pattern qualitatively: Some Bragg peaks decrease in intensity as expected, but some are enhanced. As a result some spots disappear and some new ones appear. The diffuse scattering is also calculated. Results are given comparing calculated diffraction patterns in fivefold, threefold, and twofold symmetry directions for a 3D quasicrystal with and without mistakes

Electronic structure of a quasiperiodic system

The general solution of a Schrödinger equation with a quasiperiodic potential in n dimensions is obtained. A boost technique is presented, which will transform the problem to the solution of a periodic pseudo-Schrödinger equation in n+m dimensions, to which Floquet-Bloch theory is applicable. We show that the eigenfunctions of the original problem and the boosted problem are related to each other by a simple radon transform, and the eigenvalues are exactly equal. We identify the hierarchical gap structure in the energy spectrum observed in numerical simulations and we show that the location of gaps can be indexed by the reciprocal wave vector given by the diffraction pattern of the quasicrystal. The position and the magnitude of the gaps so predicted are in qualitative agreement with numerical simulations