Random Point Sets on the Sphere-Hole Radii, Covering, and Separation

Geometric properties of N random points distributed independently and uniformly on the unit sphere (Formula presented.) with respect to surface area measure are obtained and several related conjectures are posed. In particular, we derive asymptotics (as N → ∞) for the expected moments of the radii of spherical caps associated with the facets of the convex hull of N random points on (Formula presented.). We provide conjectures for the asymptotic distribution of the scaled radii of these spherical caps and the expected value of the largest of these radii (the covering radius). Numerical evidence is included to support these conjectures. Furthermore, utilizing the extreme law for pairwise angles of Cai et al., we derive precise asymptotics for the expected separation of random points on (Formula presented.)

Use of the big liquid argon spectrometer BARS for neutrino and cosmic ray studies

The design of the fine grained 300 t liquid argon calorimeter BARS is described. The BARS electronics include about 30 K channels of low noise amplifiers and ADCs. The DAQ system makes it possible to select channels with signals above the chosen threshold. 48 scintillation hodoscopes placed inside the liquid argon are used to form the first level trigger. The total number of scintillation counters in liquid argon is 384. Sums of ionization signals are used to produce the second level trigger. Results of the first use of liquid argon calorimetry for the measurements of tagged neutrino interactions, cosmic-ray muon spectra and composition of extensive atmospheric showers are discussed. (C) 1998 Elsevier Science B.V. All rights reserved

Mice, microbes and models of infection.

We urgently need animal models to study infectious disease. Mice are susceptible to a similar range of microbial infections as humans. Marked differences between inbred strains of mice in their response to pathogen infection can be exploited to analyse the genetic basis of infections. In addition, the genetic tools that are available in the laboratory mouse, and new techniques to monitor the expression of bacterial genes in vivo, make it the principal experimental animal model for studying mechanisms of infection and immunity