Sleuthing in reciprocal space: the search for a charge-density wave in alphauranium

This year marks the 50th anniversary of the preparation of the first transuranium elements, neptunium and plutonium though thus losing pride of place in the Periodic Table, uranium still has secrets to reveal. This article describes efforts to characterize the extremely subtle series of distortions that appears at low temperature in the element. Our understanding of these distortions require some of the latest ideas in diffraction physics, so that the story is a continuously evolving one. Uranium is the only element (so far) that has been found to have a spontaneous charge-density wave.     

A conceptual model of taste receptors

Of all the senses, that of taste is perhaps the hardest to define and quantify and elucidation of the underlying mechanisms is unrespondingly difficult. This article describes a conceptual model — at the molecular level — for the four basic taste modalities, using apparent specific volume as a fundamental parameter. It also considers possible practical applications.     

Optimization of configurations of field problem grids using network models

Optimization of grid configurations decreases the discretization error in the numerical solution of field problems. In this paper, the theoretical and algorithmic aspects of optimizing configurations of grids used in equilibrium, potential-type field problems is presented. The criterion for establishing the optimum grid and the steps required to move to the optimum grid are given. Sensitivity network modelling is invoked to systematically form matrices required in the algorithm. One-dimensional examples are presented to illustrate the validity of the approach.     

Dynamic dictionary updating

A method for updating the dictionary in a dynamic information retrieval system is presented. It is shown that as a collection changes through addition and deletion of documents, the appropriate set of index terms may be determined without complete periodic regeneration of the dictionary. Results are presented for experiments involving a complete change in collection membership, with the dynamic dictionary updating methods shown to be effective.     

Polymorphonuclear leukocytic sialic acid and sialidase activity in obesity

The level of sialic acid in the obese polymorphonuclear leukocytes (PMNL) was found to be significantly reduced as compared to normal. Activity of sialic acid degrading enzyme, sialidase, was found to be increased in the obese state. Restoration in both sialic acid content and sialidase activity was also evidenced in the PMNL of treated obese patients.     

On preservation of mean square continuity under zero memory non-linear transformation

Mean square continuity of a random process is of considerable theoretical and practical importance. Mean square continuous random processes passed through zero memory non-linearities are considered. Several conditions are given relating to mean square continuity of the output. Bounded zero memory non-linearities are considered with arbitrary random processes as inputs, and conditions on both the zero memory non-linearity and on the random process are examined. Also, general zero memory non-linearities are considered with Gaussian random processes as inputs.