Resistance vs. pressure of single-wall carbon nanotubes

Received: 23 January 1998     

Geomagnetic bending and effective angles of approach of the cosmic rays for various stations

Data from 20 neutron monitor stations are used to estimate an effective geomagnetic bending for cosmic rays causing the diurnal variation of the neutron component at these stations. Correlation functions between each pair of stations were computed for that purpose and the temporal shifts giving the peak correlation were found.Devoted to Professor V. Petrílka on his sixty-fifth birthday.     

A stereoselective synthesis of 1,2-diols from α-hydroxyaldehydes

The addition of lithium acetylides to (20R)-20-hydroxypregnane-22-carboxaldehydes in the absence and in the presence of BF₃ afforded predominantly 20R,22R- or 20R,22s-diols, respectively, characteristic of ecdysones.     

Riccati equations and Lie series

Lie series and a special matrix notation for first-order differential operators are used to show that the Lie group properties of matrix Riccati equations arise in a natural way. The Lie series notation makes it evident that the solutions of a matrix Riccati equation are curves in a group of nonlinear transformations that is a generalization of the linear fractional transformations familiar from the classical complex analysis. It is easy to obtain a linear representation of the Lie algebra of the nonlinear group of transformations and then this linearization leads directly to the standard linearization of the matrix Riccati equations. We note that the matrix Riccati equations considered here are of the general rectangular type.