Discontinuous Molecular Dynamics for Semi-Flexible and Rigid Bodies

A general framework for performing event-driven simulations of systems with semi-flexible or rigid bodies interacting under impulsive torques and forces is outlined. Two different approaches are presented. In the first, the dynamics and interaction rules are derived from Lagrangian mechanics in the presence of constraints. This approach is most suitable when the body is composed of relatively few point masses or is semi-flexible. In the second method, the equations of rigid bodies are used to derive explicit analytical expressions for the free evolution of arbitrary rigid molecules and to construct a simple scheme for computing interaction rules. Efficient algorithms for the search for the times of interaction events are designed in this context, and the handling of missed interaction events is discussed.Comment: 16 pages, double column revte

Communications Biophysics

Contains research objectives, summary of research and reports on four research projects.National Institutes of Health (Grant 5 P01 GM14940-05)National Institutes of Health (Grant 5 TOl GM01555-05)National Aeronautics and Space Administration (Grant NGL 22-009-304)B-D ElectrodyneBoston City Hospital Purchase Order 1065

Communications Biophysics

Contains research objectives, summary of research and reports on three research projects.National Institutes of Health (Grant 5 PO1 GM14940-06)National Institutes of Health (Grant 2 TOl GM01555-06)National Institutes of Health (Grant 1 ROl NS10737-01)National Aeronautics and Space Administration (Grant NGL 22-009-304)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300B-D Electrodyne Division, Becton Dickinson and Company (Grant)Boston City Hospital Purchase Order 1176-21-33

Basic Methods for Computing Special Functions

This paper gives an overview of methods for the numerical evaluation of special functions, that is, the functions that arise in many problems from mathematical physics, engineering, probability theory, and other applied sciences. We consider in detail a selection of basic methods which are frequently used in the numerical evaluation of special functions: converging and asymptotic series, including Chebyshev expansions, linear recurrence relations, and numerical quadrature. Several other methods are available and some of these will be discussed in less detail. We give examples of recent software for special functions where these methods are used. We mention a list of new publications on computational aspects of special functions available on our website

ANALYTICAL PROCEDURE MANUAL FOR A RADIUM RECOVERY PROCESS

A compilation is given of analytical procedures used in the laboratory- scale separation of radium from sulfateinsoluble residues from African pitchblende processing. Included in five alternate procedures are quantitative analyses for silica, lead, copper, molybdenum, barium, nickel, calcium, magnesium, radium, moisture, water-solubles, nitrate, silver, manganese, zinc, carbon dioxide, sulfate, and chromium. (auth