Electronic speckle pattern interferometry (ESPI)

Electronic Speckle Pattern Interferometry (ESPI) is becoming a very common test and measurement tool among industrial users. In its present form it rivals any current techniques for speed and ease of use. With improvements in image quality it has the potential to become the definitive tool for non-destructive testing.     

Large deviations and the distribution of pre-images of rational maps

In this article we prove a large deviation result for the pre-images of a point in the Julia set of a rational mapping of the Riemann sphere. As a corollary, we deduce a convergence result for certain weighted averages of orbital measures, generalizing a result of Lyubich.The first author was supported by a Royal Society University Fellowship during part of this research.     

Requirements of a Package for N-Body Simulations of the Solar System

N-body simulations of the Solar System form a challenging set of initial value problems for numerical integrators. The challenge comes from the variety of problems and their size – one recent simulation had 300,015 second order equations and required 9×10¹⁰ integration steps. A number of packages for specific types of simulations are available. I discuss what is required of a package intended to efficiently perform a wide range of N-body simulations.     

A study of liquid-membrane perchlorate-selective electrodes made from an organic radical ion salt

Liquid-membrane electrodes were prepared from solutions of N-ethyl-benzothiazole-2,2′-azaviolene perchlorate in 1,2-dichlorobenzene and in β,β′-dichlorodiethyl ether, and their response and selectivity characteristics were examined. Perchlorate response ranges of the order I–10^?6.5M and 1–10^?5.6M were shown to be attainable with the two systems, respectively. These values represent significant improvements over the range 1–10^?4.8M found for the solid-state electrode made from the same radical ion salt. Short response times and acceptably stable potentials were observed for both liquid-membrane sensors. Both showed high apparent selectivities for perchlorate over all the ten anions tested. Iodide and tetrafluoroborate were the most serious interferences in each case. The low interference shown by hydrogen and hydroxide ions indicated that perchlorate determinations may be performed within the pH range 1–12 with both electrodes.     

Substituent directive effects in 1,2-benzodiazepine synthesis via electrocyclic aromatic substitution by the diazo-group: a rearrangement of 9- to 7-substituted 3H-1,2-benzodiazepines

The directive effect of aryl-substituents on the site of ring closure in the electrocyclisation of 1-aryl-3-diazoalkenes has been investigated. At 80°C the product ratio is determined by kinetic control but for some substituents the kinetically favoured 9-substituted 3$\text{H}$-1,2-benzodiazepines undergo a new rearrangement to their more stable 7-substituted isomers.