InGaAs/AlAs/InGaAsP resonant tunneling hot electron transistorsgrown by chemical beam epitaxy

InP-based resonant tunneling hot electron transistors (RHET's) were studied systematically using chemical beam epitaxy (CBE) for the first time. All the RHET's studied have a highly strained AlAs/In_0.75Ga_0.25As/AlAs resonant tunneling double barrier as a hot electron injector, and an InP collector barrier with or without InGaAsP graded layers. The highest transport ratio (α) observed is 0.98, and the highest peak-to-valley current ratios (PVR's) measured are 20 and 200 in the collector current and base current, respectively, at 80 K. A self-consistent simulation is used as a reference to optimize the hot electron injector and to explain the ballistic transport. An energy spectrometer technique was applied to the RHET's for resolving the hot electron energy distribution which showed a full width at half maximum (FWHM) of around 58 meV, indicating ballistic transport of electrons. Finally, room temperature transistor action was also observed with a β of 4 and a cutoff frequency of 31 GHz     

Tower of London performance in relation to Magnetic Resonance Imaging following closed head injury in children.

To investigate the relationship of severity of pediatric closed head injury (CHI), the contribution of frontal lobe lesions, and age at testing (6–10 yr olds vs 11–15 yr olds) to cognitive deficit, 134 head-injured patients were given the Tower of London (TOL) task and underwent magnetic resonance imaging. 89 normal controls were given the TOL for comparison. Severity of CHI and age at testing were strongly related to cognitive performance on the TOL, including the frequency of breaking the rules. Volume of frontal lobe lesion (but not extrafrontal lesion) contributed to the prediction of perfomance on the TOL even after severity of injury was taken into account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Outcome of different treatment mixes in a multidimensional neuropsychological rehabilitation program.

Within a clinical demonstration program, 59 traumatically brain-injured patients were treated with 1 of 3 mixes of treatment. Mix 1 included cognitive remediation (CGR), small-group interpersonal (SGI) communication training, therapeutic community activities, and personal counseling. Mix 2 was similar to Mix 1 but stressed SGI exercises and eliminated CGR. Mix 3 emphasized CGR and eliminated SGI exercises. The efficacy of the treatment mixes was evaluated with performance on neuropsychological tests, improved independence in functional activities, measures of intra- and interpersonal functioning, and vocational outcome. Ss' participation in the program, irrespective of treatment mix, yielded improvements in (1) self-image, (2) quality of interpersonal relatedness and interaction, (3) involvement with others in naturalistic settings, and (4) vocational outcome. Overall, data point to the superiority of the balanced mix (Mix 1) over Mixes 2 and 3. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solving educational problems: Working across institutional, cultural and political differences.

The resources of various settings located in one geographic area of a state were linked in an attempt to resolve educational problems. Using the concept of collegium as the mechanism for working together, the assumptions governing these efforts are presented, rationale for successes and failures are discussed, and suggestions are made on how such undertakings may relate to the field of school psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of temperature on methyl radical generation over Sr/La2O3 catalysts

The role of gas phase CH₃ radicals in the oxidative coupling of CH₄ over 1 wt% Sr/La₂O₃ is supported by the observations that (i) this is a very effective catalyst for the generation of CH₃ · radicals and (ii) the concentration of CH₃ · radicals increases with temperature over the range of 450 °C–800 °C.     

A strategy for the electro-organic synthesis of new hydrocaffeic acid derivatives

Electrochemical treatment processes can significantly contribute to the protection of the environment through the minimization of waste and toxic materials in effluents. From a pharmaceutical point of view and due to the existing resemblance between the electrochemical and biological reactions, it can be assumed that the oxidation mechanisms on the electrode and in the body share similar principles. In this paper, the application of electrochemical studies in the design of an environmentally friendly method was delineated for the new hydrocaffeic acid (HCA, 3,4-dihydroxy hydrocinnamic acid) derivatives synthesis at carbon electrodes in an undivided cell. In this cell, the EC mechanism reaction was involved, comprising two steps alternatively; (1) electrochemical oxidation and (2) chemical reaction. In particular, the electro-organic reactions of HCA, an important biological molecule, were studied in a water–acetonitrile (90:10 v/v) mixture in the presence of benzenesulfinic acid (3) and p-toluenesulfinic acid (4). The research included the use of a variety of experimental techniques, such as cyclic voltammetry, controlled-potential electrolysis and product spectroscopic identification.     

Aspects of three-dimensional constrained Delaunay meshing

Presented in this paper are the theoretical aspects of node addition to a non-convex, multiboundary mesh of tetrahedral elements as used in finite element modelling. The method used is derived from Watson¹ and Shenton and Cendes² and is extended to deal with node addition on inter-material boundaries. Several situations are identified that result in an illegal insertion polyhedron (IP), these could be caused by the ‘constrained’ nature of the mesh, adjacent objects with different material properties, or degenerate node configurations. A new Delaunay algorithm is described that checks for illegal cases of the IP and then corrects them, this checking relies on the consistent ordering of the element nodes. It is shown that a particular type of illegal IP can easily be identified and corrected using this technique. The Delaunay algorithm is then applied to automatic mesh generation, and modification to the basic Delaunay algorithm is described so that previously meshed edges and faces of the current object being meshed are not deleted during the addition of subsequent nodes. This ‘protection’ method only becomes viable by recognizing the node ordering sense of the IP faces.     

Bound for Minkowski metric or quadratic metric applied to VQcodeword search

A bound for a Minkowski metric based on L_p distortion measure is proposed and evaluated as a means to reduce the computation in vector quantisation. This bound provides a better criterion than the absolute error inequality (AEI) elimination rule on the Euclidean distortion measure. For the Minkowski metric of order n, this bound contributes the elimination criterion from the L₁ metric to L _n metric. This bound can also be an extended quadratic metric which can be a hidden Markov model (HMM) with a Gaussian mixture probability density function (PDF). In speech recognition, the HMM with the Gaussian mixture VQ codebook PDF has been shown to be a promising method     

FORUM for International Cooperation on Fire Research

The FORUM for International Cooperation on Fire Research is an informal group of people committed to fire research and the application of fire-research results. Since it was formed in 1988, the FORUM has brought together organizational leaders who direct resources for fire research throughout the world. This article is reprinted from the Nordic Fire Safety Engineering Symposium, Development and Verification of Tools for Performance Codes, August 30–September 1, 1993, in Espoo, Finland.