O.R. Education — A Survey of Young O.R. Workers

This paper presents the results of a survey into O.R. education that was conducted with the help of those attending the Young O.R. Conference (YOR II) held at Nottingham University in March 1982. The results of a workshop debate held at the conference into the direction of O.R. education are also discussed.The conclusions drawn are that O.R. education in this country appears to be quite successful but that it is failing to deal satisfactorily with a number of issues. These issues relate to keeping up-to-date with changes in computer technology and their impact upon O.R. workers; the teaching of methodology to deal with ill-defined problems; preparation for the political and working environment of organizations; and the fostering of desirable personal characteristics.     

Linear transformations on matrices: The invariance of commuting pairs of matrices

Let L be a linear transformation on the set of all n×n matrices over an algebraically closed field of characteristic 0. It is shown that if AB=BA implies L(A)L(B)=L(B)L(A) and if either L is nonsingular or the implication in the hypothesis can also be reversed, then L is a sum of a scalar multiple of a similarity transformation and a linear functional times the identity transformation.     

Chapter 9: miscellaneous preserver problems

This chapter consists of three sections of miscellaneous results. Each is self contained with its own abstract, but the references are in one group at the very end of the chapter. The first section considers matrices over semirings. The second concerns a function on a matrix space M which commutes with a linear operator on M. The third considers linear operators preserving certain properties associated with positive semidefinite matrices.     

Erratum: Fixed Routes

Journal of the Operational Research Society -     

MINIMUM DOSES OF ULTRAVIOLET RADIATION REQUIRED TO INDUCE MURINE SKIN EDEMA and IMMUNOSUPPRESSION ARE DIFFERENT and DEPEND ON THE ULTRAVIOLET EMISSION SPECTRUM OF THE SOURCE*

Many photoimmunological studies have used UV radiation sources that emit nonsolar UV spectral energy and UV doses based on nonimmunological endpoints, e.g. erythema and skin edema. Interpretation of these data has led to misunderstanding when extrapolated to hypothetical effects in humans exposed to solar UV. The purpose of this study was to: (1) establish UV dose response relationships for murine skin edema and immunosuppression, and (2) determine how different UV spectra affect these relationships. Back skin and ear minimum edema doses (MEdD) for Kodacel-filtered FS20 sunlamp UV (290–400nm) were greater than two-fold higher than those for unfiltered FS20 sunlamp UV (250–400nm). Xenon arc solar simulator UV (295–400nm) MEdD were > 10-fold higher than those for unfiltered sunlamp UV. Back skin and ear MEdD differed two- to five-fold between C3H/ HeN, SWR/J and HRA/Skh-1 mice. The minimum immunosuppression doses (MISD) in C3H mice showed similar UV source spectrum dependence. The solar simulator UV MISD was 5.4- and 1.5-fold higher than for unfiltered and Kodacel-filtered sunlamp UV MISD, respectively. Furthermore, MISD were from 3- to 50-fold higher than the MEdD for the three UV sources. The UV bioeffectiveness spectra indicated that UVC energy (250–290nm) contributed 12% and 18%, respectively, of the total skin edema and immunosuppression UV energy. These data demonstrate the variability in UV sensitivity among mouse strains, the significant differences between murine MEdD and MISD and how these differences are influenced by nonsolar regions (below 295 nm) of the UV spectrum.