Witt equivalence of central simple algebras with involution

The notion of Witt equivalence of central simple algebras with involution is introduced. It is shown that the standard invariants, i.e. the discriminant, the signature and the Clifford algebra, depend only on the Witt class of the algebra with involution. For a given filedF the tensor product is used to construct a semigroup\(\tilde S\left( F \right)\) and this semigroup is shown to have properties analogous to the multiplicative properties of the Witt ring of quadratic forms overF.     

Eigenfunctions on symmetric spaces with distribution-valued boundary forms

A characterization is given for those eigenfunctions of invariant differential operators on symmetric spaces of noncompact type which are representable as generalized Poisson integrals of distributions on the boundary, the criterion being that the function grow no faster than some power of the exponential of the distance from the origin. For symmetric spaces of arbitrary rank, the result is proved in one direction only, namely, that the Poisson integral of a distribution satisfies the growth condition; however, for rank one symmetric spaces, the converse is also shown to be true.     

IFECS—an interactive finite element computing system

The development philosophy and implementation of IFECS (an interactive finite element computing system) is described. The system, written in BASIC-PLUS for the RSTS/E computing system, provides solutions for various classes of stress problems in two dimensions. IFECS contains an automatic mesh generator, solution routines and an interactive means of interrogating the program output. This latter feature provides the user with the means of directly selecting relevant information, rather than having to wade through vast reams of the total output. The system, which may be implemented on a very simple computing configuration, is very easy to use and for many problems reduces the effective solution time to a few hours.     

The numerical simulation of multiphase flow through a porous medium and its application to reservoir engineering

The analysis of multiphase flow in porous media is of considerable significance in the field of petroleum reservoir simulation, where accurate predictions of fluid flow are important in assessing the performance of oil and gas fields. The specific case of two-phase immiscible flow is considered by first deriving the governing nonlinear partial differential equations. The space discretization is then carried out making use of the additional versatility of the finite element method compared with originally used finite differences. By using a pair of dependent variables P and R, the bandwidth of the discrete space-continuous time equations may be reduced to increase significantly the speed of the algorithm. A discussion of time-stepping methods is followed by an application of the technique to a five-spot,an extraction pattern used in the field. The boundary conditions used to simulate this flow pattern are also discussed.     

Quantitative evaluation of liposomal doxorubicin and its metabolites in spheroids

Analytical and Bioanalytical Chemistry - Accurate measurement and understanding of therapeutic uptake and metabolism is key in the drug development process. This work examines the amount of...     

Electrospray ionization enters the final frontier: Mass spectrometry's role in understanding electrospray thrusters and their plumes

Electrospray thrusters using ionic liquid (IL)‐based propellants are quickly gaining popularity in spacecraft design. Mass spectrometry is especially well‐suited to provide important knowledge on the fundamentals of how these systems work and on evaluating their efficiencies and impacts, given that the operating principles of electrospray thrusters closely mimics the mass spectrometry experiment – in both ions are generated by electrospray and then enter a vacuum. Here, electrospray thruster technology and IL‐based propellants are briefly introduced. This introduction is then followed by a discussion of mass spectrometry's current contribution to the study of IL‐based electrospray thrusters – with a focus on electrospray, dissociation, and spectroscopy studies – and a brief discussion of areas ripe for immediate contributions from the mass spectrometry community.     

Noise-enhanced human balance control

Noise can enhance the detection and transmission of weak signals in certain nonlinear systems, via a mechanism known as stochastic resonance. Here we show that input noise can be used to improve motor control in humans. Specifically, we show that the postural sway of both young and elderly individuals during quiet standing can be significantly reduced by applying subsensory mechanical noise to the feet. We further demonstrate with input noise a trend towards the reduction of postural sway in elderly subjects to the level of young subjects. These results suggest that noise-based devices, such as randomly vibrating shoe inserts, may enable people to overcome functional difficulties due to age-related sensory loss.