A scale mixer model for sis waveguide receivers

We report results from measurements of a scale mixer model, built to investigate the embedding impedance presented to a superconductor-insulator-superconductor (SIS) tunnel junction detector in a full height waveguide with two tuning elements. The embedding impedance is measured as a function of junction position across the waveguide channel. The results are compared to i) computer simulations of the embedding impedance using waveguide theory, ii) a lumped element circuit derived from the theory, iii) an SIS receiver operating between 200 and 280 GHz.     

Noise and responsivity of commercial p+n Ge avalanche photodiodes

Commercial p+n Ge APD samples from two manufacturers are shown to have comparable noise and responsivity, characterised by a quantum efficiency at 1.3 ?m wavelength of 0.7?0.75, and a bulk leakage current density at 20 C of 2?3×10?4 A cm?2 before avalanche multiplication. Surface uniformity of avalanche gain is much better than on earlier n+p devices of the same diameter (100 ?m).     

Glass-fibre waveguide with a triangular core

A new form of glass-fibre waveguide is described that has a triangular core. Estimates for the higher-mode cutoff of the guide are compared with values obtained by computer and by experiment.     

Using tries to eliminate pattern collisions in perfect hashing

Many current perfect hashing algorithms suffer from the problem of pattern collisions. In this paper, a perfect hashing technique that uses array-based tries and a simple sparse matrix packing algorithm is introduced. This technique eliminates all pattern collisions, and, because of this, it can be used to form ordered minimal perfect hashing functions on extremely large word lists. This algorithm is superior to other known perfect hashing functions for large word lists in terms of function building efficiency, pattern collision avoidance, and retrieval function complexity. It has been successfully used to form an ordered minimal perfect hashing function for the entire 24481 element Unix word list without resorting to segmentation. The item lists addressed by the perfect hashing function formed can be ordered in any manner, including alphabetically, to easily allow other forms of access to the same list     

Percutaneous penetration of octyl salicylate from representative sunscreen formulations through human skin in vitro

The human skin penetration of [14C]octyl salicylate from two representative sunscreen vehicles was determined in vitro. 3H-sucrose was incorporated into all formulations and provided a marker for membrane integrity. When applied as a finite dose in an oil-in-water emulsion vehicle containing 5% (w/w) octyl salicylate, the average total absorption of 14C over 48 hr was 0.65+/-0.16% of the applied dose (representing a total amount permeated of 1.58+/-0.36 microg/cm2). When applied as an infinite dose in the oil-in-water emulsion vehicle the average total absorption of 14C over 48 hr was 0.47+/-0.22% of the applied dose (representing a total amount permeated of 27.54+/-13.91 microg/cm2). When applied as a finite dose in a representative hydroalcoholic formulation containing 5% (w/w) octyl salicylate, the average total absorption of 14C over 48 hr was 0.59+/-0.09% of the applied dose (representing a total amount permeated of 1.58+/-0.25 microg/cm2). When applied as an infinite dose in the hydroalcoholic formulation the average total absorption of 14C over 48 hr was 0.23+/-0.05% of the applied dose (representing a total amount permeated of 11.28+/-2.55 microg/cm2). The penetration of [14C]salicylic acid [applied at a concentration of 2.7% (w/w), in the oil-in-water emulsion] was also determined. When applied as a finite dose the average total absorption of 14C over 48 hr was 1.14+/-0.23% of the applied dose (representing a total amount permeated of 1.65+/-0.39 microg/cm2). These results suggest that the in vitro human skin permeation of octyl salicylate is relatively low. The amounts of octyl salicylate and salicylic acid permeated when applied in similar vehicles were remarkably similar over 48 hr (1.58 microg/cm2 and 1.65 microg/cm2, respectively). This suggests the possibility that the 14C label appearing in the receptor fluid may, in both cases, represent salicylic acid. If this is the case, then it is possible that the amount of octyl salicylate permeating through the skin is much less than that suggested by the data obtained here. This supposition is, however, entirely speculative and has yet to be confirmed experimentally.     

Neurogenic oedema and vasodilatation: effect of a selective neuronal NO inhibitor

The effects of a neuronal nitric oxide synthase (nNOS) inhibitor, 1-(2-trifluoromethylphenyl)imidazole (TRIM) on rat sensory saphenous nerve-induced neurogenic inflammation were investigated. TRIM (50 mg kg-1, i.p.), but not 2-trifluoromethylphenol (TRIMPOH) which lacks nNOS inhibitory activity, inhibited neurogenic oedema by 55.8 +/- 6.5% (n = 6, p < 0.05). The effect of TRIM was partially reversed by L-arginine (100 mg kg-1, i.v., p < 0.01). TRIM also caused a reduction (p < 0.05) in neurogenic vasodilatation but had no effect on neuropeptide responses induced by substance P + CGRP. Topically applied TRIM (100 microliters of 150-250 mg ml-1) inhibited neurogenic oedema (p < 0.01). Thus, use of this recently described nNOS inhibitor has provided new evidence to further the hypothesis that nNOS plays a role in modulating sensory nerve-mediated neurogenic inflammation.     

Measures of early academic skills: Reliability and validity with a first grade sample.

This study investigated the reliability- (interscorer and test-retest) and criterion-related validity (concurrent and predictive) of 11 curriculum-based measures of early academic skills with a sample of first-grade students. Some measures required production-type responses. Other measures required selection-type responses. The measures involved letters (sounds, names, copying), numbers (names, counting in sequence), colors, and shapes. Subjects were 30 first-grade students from an urban parochial school. Test-Retest reliability was assessed with alternate forms of the measures over a two-week interval. Concurrent validity was assessed with a norm-referenced achievement test (the Woodcock-Johnson Revised). Predictive validity was assessed by measuring oral reading fluency in passages and on word-lists four months after the initial assessment. Results suggested that some measures displayed better reliability and validity than others. The practical utility of these measures in light of their technical characteristics and the need for further construct validity data are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phototransistors in digital optical communications systems for 1?1.6 ?m wavelength

Receiver sensitivity comparable with that of a PIN-FET hybrid should be attainable using phototransistors at bit rates below 1 Gbit/s. However, significant improvement would call for a phototransistor having a very low input capacitance C and a high current gain hFE satisfying C<2×10?3?(hFE) pF, incorporated into an integrating receiver design.     

Ferroelectric Domain Structure of Lanthanum-Modified Lead Titanate Ceramics

The ferroelectric domain configurations in lanthanummodified lead titanate ceramics have been studied by transmission electron microscopy in conventional, analytical, and high-resolution modes. Results indicate a preponderance of (101), twin-related 90° domains of equilibrium width 50 to 100 nm. These values are consistent with those derived from consideration of elastic strain energy. Below a critical grain size of approximately 0.3 μm, single-domain grains are found. A domain wall energy of 1 mJ/m² was calculated based on this observation. Within such twins are occasionally found ordered domains, displaying little or no misorientation with respect to one another. In addition, (001), 180° domains were observed.