Length preferences and periodicity in {beta}-strands. Antiparallel edge {beta}-sheets are more likely to finish in non-hydrogen bonded rings

We analysed the length distributions of different types of ß-strandin a high resolution, non-homologous set of 500 protein structures,finding differences in their mean lengths. Antiparallel edgestrands in strand–turn–strand motifs show a preferencefor an even number of residues. This propensity is enhancedif the length is corrected for ß-bulges, which insertan extra residue into the strand. Residues in antiparallel edgeß-strands alternate between being in hydrogen bondedand non-hydrogen bonded rings. Antiparallel edges with an evennumber of residues are more likely to have their final ßresidue in a non-hydrogen bonded ring. This suggests that non-hydrogenbonded rings are intrinsically more stable than hydrogen bondedrings, perhaps because its side chain packing is closer. Therefore,we suggest that a simple way to increase ß-hairpinstability, or the stability of an antiparallel edge strand,is to have a non-hydrogen bonded ring at the end of the strand. Received June 19, 2003; revised October 25, 2003; accepted November 7, 2003     

Homophily horizons and ethnic mover flows among homeowners in Scotland

Abstract

This article analyses mover flows in Glasgow and the role of ethnic homophily, the tendency for movers to be drawn to areas with similar ethnicities to their own. We look at how homophily affects the spatial relocation patterns of homeowners in Glasgow from Scottish, Indian, Pakistani and Chinese descent, and focus on the extent to which homophily extends beyond the immediate locality to surrounding neighbourhoods. Our interest is in estimating the “homophily horizon” – how far the gaze of homophily reaches in mover location decisions. Using a simple Schelling-type theoretical model, we argue that homophily horizons are potentially important in shaping the long-term social structure of cities as they may profoundly affect how potent the overall sorting tendencies of the housing market are in driving segregation. In principle, the more distant the homophily horizon, the more quickly the housing market will tend towards segregation, other things being equal. We adopt Folch and Rey’s use of the local centralization index to capture the influence of surrounding neighbourhoods in shaping mover flows and neighbourhood dynamics. Our estimation combines ethnic mover flows derived from surname analysis of house buyers from the house transactions recorded in Registers of Scotland data. Our results show that the presence of the own ethnic group in the local surroundings is important for explaining mover flows, and that homophily is a local phenomenon.     

Automated Radiographic Diagnosis via Feature Extraction and Classification of Cardiac Size and Shape Descriptors

One goal of digital processing of radiographic images is to provide the radiologist with quantitative measurements of human anatomy as well as an indication as to whether or not this anatomy is within normal limits. A computer algorithm is described, designed to automatically detect, extract quantitative measurements from, and diagnose the cardiac projection present in full-size anteriorview chest radiographs. A normal-abnormal diagnosis is demonstrated utilizing abnormal data from five classes of heart disease. In addition, normal-abnormal as well as normal-differential diagnoses are demonstrated for the rheumatic heart disease class. A feature extraction algorithm is developed using several ad hoc techniques, some of which were adapted from other feature extraction uses. The extracted features are classified into diagnostic classes using linear and quadratic discriminant functions. A concurrent study of physician diagnostic accuracy is also undertaken using the averaged diagnostic rates of ten radiologists on a representative subset of the radiographs used in the computer study.     

Determinants of Mortgage Protection Insurance Take-up

The aim of this paper is to identify the factors which affect the take-up of Mortgage Payment Protection Insurance (MPPI), to estimate the sensitivity of take-up to changes in determinants. The paper finds that: (1) MPPI premiums have a negative but marginal effect on take-up; (2) the probability of being unemployed has a positive effect: a 10 per cent rise in the probability resulting in a 3 per cent increase in take-up; (3) the local male unemployment rate has a positive effect on take-up (around 1 per cent increase in take-up for every 10 per cent rise in the male unemployment rate); (4) there is likely to be a pro-cyclical element in the take-up rate, but the variation is substantially damped compared with the volatility of the unemployment cycle; and (5) ISMI cover was found to have a negligible negative effect on take-up (a 10 per cent fall in ISMI would cause a 0.3 per cent rise in take-up), an effect that could not be statistically distinguished from zero.     

Pyrotechnic reaction of titanium and barium chromate: heats of reaction and rates of burning

Heats of reaction were measured with a bomb calorimeter and rectilinear rates of burning by an electronic timer. Maximum heat of reaction and rate of burning occurred at 30% and 35% Ti respectively. The effect of preheating compositions, in loose and compacted state, was investigated. X-ray diffraction analysis indicated that the products of reaction are TiO, BaO and Cr.     

The Affordability of Water in an African Town

This paper examines (a) the ability of consumers in a typical medium-sized African town to pay for a piped water supply, and (b) the implications for the financial viability of the local water undertaking. It demonstrates that, at present, people are paying about 10% of their income for water, and this appears to be near their limit of affordability. However, it is shown that it is possible for the water company to improve its revenue, whilst maintaining its present tariffs, by providing more private connections. Furthermore, the aim of improving water-company revenues is compatible with providing improved services to its urban customers.     

Metal/oxidant combustion reactions: Variation of propagation rate with consolidation pressure

Variation of linear propagation rate with consolidation pressure has been studied for $\text{PbO}\text{Si}\text{,}\text{SnO}{}_2\text{Si}\text{,}\text{PbO}\text{B}\text{and}\text{SnO}{}_2\text{B}$ pyrotechnic systems, over a range of oxidant/fuel ratios. Compressed columns of compositions were prepared using an air operated hydraulic press, and times of linear combustion measured using an electronic timer. The observed variations in propagation rate were correlated with reduced voidage and the influence of reaction temperatures on possible heat and mass transfer mechanisms. The possible influence of hot molten liquid products in boron-fuelled systems has also been considered. There was a significant difference in the response of the silicon systems to variations in consolidation pressure and its effect on propagation. This was not so for their boron counterparts.