The current status of plasma assisted MBE growth of group III-nitrides

This article outlines very briefly our present state of knowledge concerning the growth and characterization of group III-nitrides by plasma assisted molecular beam epitaxy (PA-MBE) and also discusses the application of MBE for devices. We begin with a discussion of our current knowledge of the growth kinetics for both binary compounds (AlN, GaN and InN) and for alloys with mixed group III (InGaN and AlGaN) and group V (AlAsN and GaAsN) elements. We emphasize the important role that the choice of substrates, stoichiometry and buffer layers play in determining the morphology of GaN. We comment briefly on the problems of doping group III-nitrides, particularly p-type, and finally we mention the present status of devices grown by MBE compared with similar devices grown by metal-organic vapour phase epitaxy (MOVPE). © 1998 Chapman & Hall     

An exploration of the problems of using function points mark II

Abstract. This paper examines critically the function point analysis mark II (FPA mark II) method of measuring the functionality of information systems. Although the focus of the paper is on FPA mark II as devised by Symons, both this and the Albrecht method, from which the FPA mark II was developed, are briefly discussed. The published attempts to validate FPA mark II are reviewed and then the problems encountered by the author in applying the approach are described. The final part of the paper is concerned with the fit between SSADM and FPA mark II.     

Hearing and Sj?gren's syndrome

Immune sensorineural hearing loss is manifested in several systemic immune diseases. Although hearing loss has been previously documented in patients with Sj?gren's syndrome (SS), the effect of SS on hearing is unclear. This prospective study was designed to assess the presence of hearing loss in 14 patients with SS and, if sensorineural hearing loss was present, to determine if the hearing loss was immune-mediated. Patients were evaluated with basic audiologic tests as well as for cellular immune inner ear reactivity as measured by the lymphocyte transformation test (LTT). Three patients had evidence of sensorineural hearing loss. Two patients had a positive LTT without evidence of sensorineural hearing loss. This preliminary study suggests that SS may not directly cause sensorineural hearing loss, immuno-mediated or otherwise.     

A Sketch-Based Interface for Clothing Virtual Characters

This interactive system for garment creation determines a garment's shape and how the character wears it based on a user-drawn sketch. The system then uses distances between the 2D garment silhouette and the character model to infer remaining distance variations in 3D     

Nanoindentation mapping of mechanical properties of cement paste and natural rocks

This paper reports a study to assess nanoindentation mapping of mechanical properties of cement paste and natural rocks. Initial work seems to show that mechanical property mapping by nanoindentation is feasible and can be related to microscopic information. Further work is however required on the effect of indent size and spacing. Such a testing technique can be very useful for materials with different phases to study the intrinsic properties of each component, and also the interaction and properties of the interfacial regions of different phases. The values of Young's modulus and hardness of the individual mineral phases were also determined by statistically analysing a large number of experimental data.     

Optical Splitting Trees for High-Precision Monocular Imaging

In this article, we consider the design of monocular multiview optical systems that form optical splitting trees, where the optical path topology takes the shape of a tree because of recursive beam splitting. Designing optical splitting trees is challenging when it requires many views with specific spectral properties. We introduce a manual design paradigm for optical splitting trees and a computer-assisted design tool to create efficient splitting-tree cameras. The tool accepts as input a specification for each view and a set of weights describing the user's relative affinity for efficiency, measurement accuracy, and economy. An optimizer then searches for a design that maximizes these weighted priorities. Our tool's output is a splitting-tree design that implements the input specification and an analysis of the efficiency of each root-to-leaf path. Automatically designed trees appear comparable to those designed by hand; we even show some cases where they are superior. With the help of the optimizer, the system demonstrates high dynamic range, focusing, matting, and hybrid imaging implemented on a single, reconfigurable camera containing eight sensors     

MQW wavelength-tunable DBR lasers with monolithically integrated external cavity electroabsorption modulators with low-driving voltages fabricated by selective-area MOCVD

The design and operation of multiple-quantum-well (MQW) wavelength-tunable distributed Bragg reflector (DBR) InGaAs QW lasers with nonabsorbing gratings and monolithically integrated external cavity electroabsorption modulators fabricated by selective-area MOCVD are presented. Uncoated devices exhibit CW threshold currents as low as 10.5 mA with slope efficiencies of 0.21 W/A from the laser facet. Wavelength tuning of 7 nm is obtained by injection current heating of the DBR section. These devices also exhibit extinction ratios of 18 dB from the modulator facet at a low modulator bias of 1 V, when measured with a broad-area detector. When coupled to a singlemode fiber, these devices exhibited high extinction ratios of 40 dB at a modulator bias of 1.25 V.