An ISDN for the UK

With the advent of new digital technology into public telecommunications networks and given the fact that voice and data are carried in essentially the same way across a digital network, it is realized that the integration of voice and data services is possible and cost effective, and may bring additional benefits. The paper sets out some of the current developments in this area, with an emphasis on British Telecom's pilot Integrated Services Digital Network.     

Lipid-protein interactions with native and modified myelin basic protein

The basic protein of central nervous system myelin has been shown to form complexes with acidic lipids in vitro. We measured the interaction of myelin basic protein with several charged and neutral lipids in a biphasic chloroform/methanol/water system and investigated the effect of decreasing the electrical charge of the basic amino groups of the myelin basic protein by acetylation. The modified myelin basic protein, which has an average of eight acetyl residues incorporated, was characterised by gel electrophoresis and circular dichroism. Complexes formed between the acetylated myelin basic protein and acidic lipids exhibited a reduction in the amount of lipids bound, a value that could be correlated with the number of modified amino groups. The significance of these experiments with reference to protein-lipid interaction in the myelin membrane is discussed.     

Quantitative cytochemical changes induced by dexamethasone and adrenalectomy in rat liver chromatin

A wild-type strain of Staphylococcus aureus, which inactivates a wide variety of aminoglycosides (except the gentamicin components), has been found to harbor a plasmid (RAp01) that mediates the biosynthesis of a nucleotidyltransferase. This enzyme modifies the 4'-hydroxy function of these antibiotics. The plasmid has been studied, the enzyme responsible for this resistance pattern has been isolated by affinity chromatography, and its kinetics and physicochemistry have been characterized. The target of this enzyme has also been located by demonstrating the structure of one inactivated compound, 4'-(O)-adenylyltobramycin.     

The use of anabolic steroids by athletes to increase body weight and strength

Over the past 20 years the taking of anabolic steroids by healthy athletes for the purpose of increasing body weight and strength has become very widespread. The ability of these agents to cause potentially serious side effects is discussed. In a series of 20 subjects studied over 18 months, no side effects of significance were recorded, and marked increases in strength and body weight were achieved.     

Shape deformations in rough-surface scattering: improved algorithms

We present new, stabilized shape-perturbation methods for calculations of scattering from rough surfaces. For practical purposes, we present new algorithms for both low- (first- and second-) and high-order implementations. The new schemes are designed with guidance from our previous results that uncovered the basic mechanism behind the instabilities that can arise in methods based on shape perturbations [D. P. Nicholls and F. Reitich, J. Opt. Soc. Am. A 21, 590 (2004)]. As was shown there, these instabilities stem from significant cancellations that are inevitably present in the recursions underlying these methods. This clear identification of the source of instabilities resulted also in a collection of guiding principles, which we now test and confirm. As predicted, improved low-order algorithms can be attained from an explicit consideration of the recurrence. At high orders, on the other hand, the complexity of the formulas precludes an explicit account of cancellations. In this case, however, the theory suggests a number of alternatives to implicitly mollify them. We show that two such alternatives, based on a change of independent variables and on Dirichlet-to-interior-derivative operators, respectively, successfully resolve the cancellations and thus allow for very-high-order calculations that can significantly expand the domain of applicability of shape-perturbation approaches.