Showing papers by "Michael D. Smith published in 1991"

Excitation of the fine-structure transitions of C in collisions with ortho- and para-H2

Abstract: The authors present the results of ab initio (SCF and CEPA) calculations of the interaction potentials for the C(3P)-H2(1 Sigma g+) system. The five potential curves corresponding to collinear (3 Sigma -,3 Pi ) and orthogonal (3A2,3B1,3B2) approaches of the C atom to the midpoint of the H2 molecule have been computed, as well as the curve of 3A' symmetry for an intermediate geometry. These results are analysed and used in quantum mechanical (close-coupling) calculations of the cross sections for excitation of the fine structure transitions in C(3PJ) by ortho- and para-H2. The rate coefficients for these transitions are evaluated for a range of temperatures encompassing those relevant to studies of the interstellar medium.

Water and Sanitation for Disasters

Abstract: INTRODUCTION The associations between sanitation, water and health are well known. These relationships gain extra importance, however, after a disaster when many of the normal controls on disease spread have been destroyed or, if people are moved to a refugee camp, do not exist. Many diseases are associated with contaminated water and water shortages. Without adequate water, people cannot wash themselves properly, nor their clothes, nor their cooking utensils and food cannot be prepared adequately or hygienically. These restrictions on cleanliness result in various parasitic, fungal and skin diseases, eye infections and diarrhoeal diseases. Studies have shown that water quantity is of greater importance than water quality: people are more likely to become ill as a result of having soiled hands, dirty eating utensils or from eating food prepared with soiled hands than from drinking contaminated water. This is not to say that the quality of water is unimportant, merely that it is less important than having sufficient water. A large quantity of water that is not completely free of bacteria is better than a small amount of pure water. Some water sources may (under normal conditions) be considered unsuitable on the basis of local preferences. The taste, odour and appearance of water must normally all be considered good for water to be acceptable for local consumption, but such preferences may not apply after a disaster, when water of any quality will serve. Many other diseases are related to poor sanitation, particularly poor excreta disposal. Sanitation is usually taken to include the disposal of all organic wastes produced by the community, ie excreta disposal, solid waste (refuse) disposal and sullage (grey water) disposal. This article will only deal with excreta disposal since this is usually the most important, particularly immediately after the disaster has occurred. Tropical Doctor, Supplement 1, 1991