Control of traveling waves in the Mammalian cortex

We experimentally confirmed predictions that modulation of the neuronal threshold with electrical fields can speed up, slow down, and even block traveling waves in neocortical slices. The predictions are based on a Wilson-Cowan-type integro-differential equation model of propagating neocortical activity. Wave propagation could be modified quickly and reversibly within targeted regions of the network. To the best of our knowledge, this is the first example of direct modulation of the threshold to control wave propagation in a neural system.     

P-Regular Convergence Spaces

A generalized notion of regularity is introduced which enables one to study locally compact spaces, sequential spaces, ω-regular spaces, and other diverse types of spaces as special wises of p-regular spaces.     

Conjugation of poor inhibitors with surface binding groups: a strategy to improve inhibition

Conjugation of surface binding groups with inhibitors for carbonic anhydrase leads to the conversion of weak inhibitors to strong inhibitors.     

Determination of fat in dairy products using pressurized solvent extraction

Gravimetric fat data were obtained for a wide range of dairy products with fat contents ranging from 0.5 to 83% using pressurized solvent extraction at elevated temperatures and pressure (80-120 degrees C; 10.3 MPa). Extraction performance was sensitive to solvent composition, temperature, and sample matrix. By optimizing solvent mixtures, sample-solvent contact times of 8-10 min were sufficient for high recoveries from all products tested. The most successful solvents with regard to speed of extraction, selectivity, and recovery (average recovery, %) were various mixtures of hexane (or petroleum ether)-dichloromethane-methanol for dried cream (99.8%), dried whole milk (99.6%), dried buttermilk (98.2%), dried skim milk (97.0%), dried whey protein concentrate (97.5%), casein (95.0%), and caseinate (102.1%); petroleum ether-acetone-ethanol or petroleum ether-acetone-isopropanol for cheddar-type cheese (99.4%); petroleum ether-acetone for butter (99.9%); petroleum ether-acetone-isopropanol for cream (100.3%); and petroleum ether-isopropanol for liquid milks (99.0%). Relative standard deviations for repeatability were obtained for dried whole milk (0.2%), dried whey protein concentrate (0.7%), cheese (0.3%), butter (0.1%), and ultraheat treated (UHT) milk (0.7%). Solvent removal and drying of extracts with a heated block evaporator saved time compared with conventional drying ovens. Estimated savings in labor (50-75%) and solvents (80%) were substantial compared with the manual Mojonnier methods.     

Approximation of Planar Convex Sets from Hyperplane Probes

This paper studies a geometric probing problem. Suppose that an unknown convex set in R ² can be probed by an oracle which, when given a unit vector, will return the position of the supporting hyperplane of the convex set that has the given vector as an outward normal. We present an on-line algorithm for choosing probing directions so that, after n probes, an inner and an outer estimate of the convex set are obtained that are within of each other in Hausdorff distance. This is optimal since there exist convex sets that, even if visible, cannot be approximated better than with n-sided polygons, for example, a circle. Received April 18, 1995, and in revised form March 28, 1996.     

Report on the standardization workshop, 11th ICTAC 1996

This was a very well attended meeting with the numbers reflecting an increasing world-wide demand for certified reference materials. This is an inevitable consequence of the growth of schemes for the accreditation of the quality of measurement.     

Symmetry-breaking and branching patterns in equivariant bifurcation theory,I

Communicated by M. Golubitsky