Adaptive simulation using mode identification

Adaptive simulation using modal clustering and method of potential function

A microbiological assay method for p-aminobenzoic acid

Since the establishment of p-aminobenzoic acid as a member of the B vitamin group, a considerable interest has been shown in methods of determination in natural materials. Since known chemical methods are not sufficiently sensitive, it became evident that microbiological tests should be the most practicable. The organism Clostridium acetobutylicum has been used (1) but no general assay procedure has been presented. Several bacterial strains which respond to p-aminobenzoic acid have been investigated in this laboratory, but satisfactory assay procedures with these organisms have not yet been devised. For the discovery of the test organism used in the procedure described in this paper, we are indebted to Dr. Beadle and Dr. Tatum who kindly furnished us with a culture of their p-aminobenzoic acid requiring a mutant strain of Neurospora crassa, designated by them as Neurospora crassa p-aminobenzoicless No. 1633 (2). This mold will grow optimally on a medium consisting of inorganic salts, ammonium tartrate, sucrose, biotin, and p-aminobenzoic acid. For purposes of assay, however, it has proved advantageous to supplement this basal medium with natural extracts which are either naturally low in p-aminobenzoic acid or have been treated to remove it. With such a complex medium, the possibility of interference by toxic substances or stimulatory substances other than p-aminobenzoic acid which might be present in samples to be assayed is reduced to a minimum. Since the completion of a considerable part of the experimental work described in this paper, microbiological assay methods for p-aminobenzoic acid have been published by Landy and Dicken (3) utilizing the organism Acetobacter suboxydans and by Lewis (4) using Lactobacillus arabinosus 17-5

Lambda hyperonic effect on the normal driplines

A generalized mass formula is used to calculate the neutron and proton drip lines of normal and lambda hypernuclei treating non-strange and strange nuclei on the same footing. Calculations suggest existence of several bound hypernuclei whose normal cores are unbound. Addition of Lambda or, Lambda-Lambda hyperon(s) to a normal nucleus is found to cause shifts of the neutron and proton driplines from their conventional limits.Comment: 6 pages, 4 tables, 0 figur

Potential algebra approach to position dependent mass Schroedinger equation

It is shown that for a class of position dependent mass Schroedinger equation the shape invariance condition is equivalent to a potential symmetry algebra. Explicit realization of such algebras have been obtained for some shape invariant potentials

Folding model analysis of proton radioactivity of spherical proton emitters

Half lives of the decays of spherical nuclei away from proton drip line by proton emissions are estimated theoretically. The quantum mechanical tunneling probability is calculated within the WKB approximation. Microscopic proton-nucleus interaction potentials are obtained by single folding the densities of the daughter nuclei with M3Y effective interaction supplemented by a zero-range pseudo-potential for exchange along with the density dependence. Strengths of the M3Y interaction are extracted by fitting its matrix elements in an oscillator basis to those elements of the G-matrix obtained with the Reid-Elliott soft-core nucleon-nucleon interaction. Parameters of the density dependence are obtained from the nuclear matter calculations. Spherical charge distributions are used for calculating the Coulomb interaction potentials. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes of proton rich nuclei for proton emissions from 26 ground and isomeric states of spherical proton emitters.Comment: 6 page