Ultra-strong, well-apodised Bragg gratings in chalcogenide rib waveguides

The first ultra-strong, near-perfect, raised-apodised Bragg gratings in As/sub 2/S/sub 3/ chalcogenide rib waveguides using /spl lambda/=532 nm light and a modified Sagnac holographic writing setup are demonstrated. Good agreement is achieved between the experimental results and the numerical modelling of the gratings using the transfer matrix analysis for thin film structures.     

Long-term working memory in the rat: Effects of hippocampally applied anisomycin.

The extent to which protein synthesis is involved in working memory was investigated with the protein synthesis inhibitor anisomycin (ANI). Male albino and Long-Evans rats were trained to perform accurately on a 12-arm radial maze when delays of 240 min were interposed between Choice 6 and Choice 7. Bilateral hippocampal cannulas were then implanted. Accuracy on Choices 7–22 was studied when ANI (80 μg/μl) or saline was injected either 30 min before Choice 1 or 5–20 min after Choice 6 in Exp I. Pretrial injection of ANI significantly impaired performance following the 240-min delay, whereas ANI injected during the delay had no such effect. In Exps II and III, the ANI-induced amnesia was replicated, and the temporal course of development of the amnesia was determined. Pretrial administration of ANI did not significantly affect retention after a 2-min delay but produced amnesia after delays of 15 min or longer. Data suggest that protein synthesis is important for the formation of temporary memories, provided the retention interval is long enough. It is suggested that working memory includes both short- and long-term components. Protein synthesis appears to be important for formation of the long-term component, but not the short-term component, of working memory. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On body-fitted co-ordinates for separated laminar flows past wall-mounted obstacles

A body-fitted curvilinear co-ordinate system is used to solve the equations of two-dimensional incompressible laminar flow over bluff obstructions by finite differences. Arbitrary conditions at the corner are removed by this method. Results for a backward-facing step are in reasonable agreement with those obtained with conventional mesh systems, and the differences are explained. A treatment of a channel expansion, in comparison with empirical data, is also included. The capability of the present method to handle arbitrary two-dimensional geometries is stressed and demonstrated, using a triangle and a semi-circle as examples.     

Counseling psychology, clinical psychology, and human services psychology: Where the twain shall meet?

Comments on the proposal by L. H. Levy et al (see record 1984-27507-001) for a new charter for clinical psychology—human services psychology. Current trends suggest that both clinical and counseling psychology are becoming eclectic and health oriented. Clinical psychology appears to be becoming more involved in community psychology and to be tempering its remedial role with the preventive role. Counseling psychology appears to be becoming less involved in its vocational and preventive roles and more involved in the remedial role. It is concluded that clinical and counseling psychology have come to be increasingly similar and could be integrated into a human services psychology. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crystallization of some anorthite-diopside glass precursors

Anorthite and diopside have been obtained from complete devitrification of glasses belonging to the quaternary system MgO-CaO-Al₂O₃-SiO₂. Microstructure, the natural trend of the nucleation mechanism and kinetic studies on the crystallization phenomenon have been investigated by means of optical and electron microscopies, thermal and thermomechanical techniques and X-ray powder diffractometry. All the glasses investigated show a complete crystallization starting from a simple surface nucleation process. The activation energy for the crystallization process proved to be higher than that for viscous flow, leading to an important aspect modification in the sample during ceramization. Thermal stability and physical properties of both glass and glass-ceramic materials have been tested, suggesting the possible use of these materials in industrial application.     

Calculation of approximate weight functions in fracture mechanics by FEM

A method is presented for the calculation of weight functions used in fracture mechanics to determine stress intensity factors of cracks loaded by stress gradients. The reference solution for the stress intensity factor and for the reference crack opening displacement field is computed numerically by use of finite elements. The accuracy of the method is checked by comparison with well-known solutions from the literature.     

Nonlinear static and dynamic analysis of circular plates and shallow spherical shells using the collocation method

The present work investigates the efficacy and applicability of interior global orthogonal point collocation method to the axisymmetric nonlinear analysis of elastic circular plates and shallow spherical shells subjected to uniformly distributed transverse load. Spacewise discretisation has been carried out using a polynomial expansion with the zeros of a Chebyshev polynomial as collocation points. Timewise integration has been carried out with Newmark k-β scheme corresponding to average acceleration method. The static response and snap-through buckling results, as well as, the dynamic response and dynamic buckling results under a uniformly distributed step load have been obtained and found to agree closely with the available results.     

An alternating technique for evaluating weight functions for 3-D surface flaws in finite solid bodies

An efficient method, based on the Schwarz–Neumann alternating technique, is presented for computing weight functions of a general solid (3-D as well as 2-D), with embedded or surface-flaw configurations. The total rate of change of the crack-opening displacements, due to simple perturbations of crack-dimension characteristics, is conveniently decomposed into the infinite-domain and boundary-correction parts. The former is determined from available analytical solutions of ideal-shaped cracks, whereas the latter is computed numerically by imposing nil boundary-traction requirements for the displacement field corresponding to the weight functions. Numerical examples, with solutions for 3-D weighted-average and local stress intensity factors, indicate that the proposed method is very accurate and efficient.     

Calculation of stress concentration in the manipulator element using a combined finite and boundary element method

Elastic stress concentration in a manipulator element is calculated within the framework of the two-dimensional stressed state model. The purpose here is to make recommendations for selecting the radius of joining of the beam parts of the element based on analysis of maximum stresses in the stress concentration zone. Combination of the finite element and boundary element methods is proposed for solving the problem. A coarse finite element subdivision is used for the initial calculation for the entire element. Then, the solution is refined by using boundary elements in the identified zone. Comparison of calculation results with solutions obtained by the finite element and boundary element methods points to the effectiveness of the proposed algorithm for stress concentration calculations.Translated from Problemy Prochnosti, No. 6, pp. 72–74, June, 1991.     

Children's cognitive function and cell-phone electromagnetic fields

Several companies have made major strides in marketing cellular telephones to children within the past 12 months; more and more children are using cell phones as part of their daily routines. Some fear any disturbance to brain activity in children could lead to impaired learning ability or behavioral problems. Moreover, any lasting biochemical effects could have important consequences, especially in the young, who still have years of development ahead of them. Recently, two studies of the mental process of young users of standard 902 MHz Global System for Mobile Communication (GSM) cellular mobile telephones were published: one paper reported a slight trend toward speeding up of simple reaction time, whereas the other study did not detect any change in cognitive functions.