Statistical studies of branched ester latex and paint properties

Vinyl versatate, butyl acrylate and 2-ethylhexyl acrylate were compared as comonomer, for colloid-stabilized vinyl acetate latex polymers to assess their impact on latex coating properties. Vinyl versatate afforded advantages in scrub resistance, gloss, hydrophobicity and higher glass transition temperatures. Butyl acrylate developed better wet adhesion efficiency, gel content and hiding efficiency. 2-Ethylhexyl acrylate offered performance comparable to butyl acrylate in hiding efficiency, lowering copolymer glass transition temperatures, and gloss development. Combinations of these monomers, in many instances, afforded a better balance of performance properties than individual monomers alone. In the subject study, a simplex-centroid design was utilized to statistically map polymer compositions for determining the effect of comonomer composition on latex and paint film properties. In addition to developing contour maps of polymer and paint properties as a function of composition, a technique for studying structure-property relationships is presented.     

Evaluating choice in universal access: an example from rehabilitation robotics

This paper describes a technique using dimensional analysis that so far has been rarely, if ever, used in studies of universal access. However, this procedure can produce a robust decision support process for inclusive designs. In this paper, it is applied to a case study of a wheelchair robot computer interface with choices in data input methods, addressing disparate requirements of different groups of intended users. The main underlying issue is to combine technical measurements, speed of operation and cost with subjective opinion. It turns out that Braglia’s method has greater robustness in determining rank compared to standard techniques. In this, case a simple switch was rated better than a mouse or voice operation for control.     

Molecular Alignment Induced by Ultrashort Laser Pulses and Its Impact on Molecular Motion

Spectroscopy aims at extracting information about matter through its interaction with light. However, when performed on gas and liquid phases as well as solid phases lacking long-range order, the extracted spectroscopic features are in fact averaged over the molecular isotropic angular distributions. The reason is that light–matter processes depend on the angle between the transitional molecular dipole and the polarization of the light interacting with it. This understanding gave birth to the constantly expanding field of “laser-induced molecular alignment”. In this paper, we attempt to guide the readers through our involvement (both experimental and theoretical) in this field in the last few years. We start with the basic phenomenon of molecular alignment induced by a single pulse, continue with selective alignment of close molecular species and unidirectional molecular rotation induced by two time-delayed pulses, and lead up to novel schemes for manipulating the spatial distributions of molecular samples through rotationally controlled scattering off inhomogeneous fields and surfaces.     

88 Great Whyte,Ramsey, Cambridgeshire: The Discovery of a Medieval Open Hall and the Dating of Carpentry Techniques in a Fenland Town

The demolition of a building at 88 Great Whyte, Ramsey, Cambridgeshire, in the early 1980s provided an opportunity to dismantle and record the remains of a two-cell medieval open hall building. Initial attempts to date the carpentry joints relied on the findings of Cecil Hewett in Essex, but it subsequently became possible to compare these findings with results of dendrochronological tests on some of the timbers as well as the findings of other building historians.     

Double frequency narrow-band grazing incidence pulsed dye lasers

A double frequency operation of the recently introduced grazing angle dye laser is demonstrated. By using two mirrors to reflect different order of diffraction the laser oscillates at two different frequencies, independently tunable over the entire gain profile of the dye.     

Small Parameter Limit for Ergodic, Discrete-Time, Partially Observed, Risk-Sensitive Control Problems

We show that discrete-time, partially observed, risk-sensitive control problems over an infinite time horizon converge, in the small noise limit, to deterministic dynamic games, in the sense of uniform convergence of the value function on compact subsets of its domain. We make use of new results concerning large deviations and existence of value functions. Date received: May 21, 1999. Date revised: April 7, 2000.