Nrc

Molecular Symmetry and Spectroscopy deals with the use of group theory in quantum mechanics in relation to problems in molecular spectroscopy. It discusses the use of the molecular symmetry group, whose elements consist of permutations of identical nuclei with or without inversion. After reviewing the permutation groups, inversion operation, point groups, and representation of groups, the book describes the use of representations for labeling molecular energy. The text explains an approximate time independent Schrödinger equation for a molecule, as well as the effect of a nuclear permutation or the inversion of E* on such equation. The book also examines the expression for the complete molecular Hamiltonian and the several groups of operations commuting with the Hamiltonian. The energy levels of the Hamiltonian can then be symmetrically labeled by the investigator using the irreducible representations of these groups. The text explains the two techniques to change coordinates in a Schrödinger equation, namely, (1) by using a diatomic molecule in the rovibronic Schrödinger equation, and (2) by a rigid nonlinear polyatomic molecule. The book also explains that using true symmetry, basis symmetry, near symmetry, and near quantum numbers, the investigator can label molecular energy levels. The text can benefit students of molecular spectroscopy, academicians, and investigators of molecular chemistry or quantum mechanics.

Acknowledgements -- References -- Chapter 5. Ecology and silviculture of poplar plantations -- Introduction -- Propagation and production of planting stock -- Planting stock types -- Stock production systems -- Unrooted dormant cuttings and sets -- Weed control strategies -- Fertilization and irrigation -- Crop health, protection, and hygiene -- Unrooted dormant branch cuttings -- Rooted dormant cuttings -- Container nursery for rooted plants -- Stock harvesting, processing, and quality control -- Harvesting -- Processing -- Quality control -- Stock packaging and storage.

This treatise begins with an introduction on the history of soil classification in Canada and discussion of the rationale for soil taxonomy. It then defines such terms as soil, pedon, and soil horizons before outlining the classification system along with identification keys. Chapters 4 through 13 describe the characteristics of the various soil orders and include information on distinguishing soils of one order from soils of other orders. Chapter 14 outlines criteria & guidelines used in differentiating classes in soil families and soil series categories. Chapter 15 provides information on distinguishing soil phases. Chapter 16 correlates Canadian soil taxonomy with other classification systems. Chapter 17 summarizes the main terminology used to describe soils at the landscape and pedon scales. The final chapter provides a system of landform classification for soil mapping.

The regulation of potentially hazardous substances has become a controversial issue. This volume evaluates past efforts to develop and use risk assessment guidelines, reviews the experience of regulatory agencies with different administrative arrangements for risk assessment, and evaluates various proposals to modify procedures. The book's conclusions and recommendations can be applied across the entire field of environmental health.

"Poplar is increasingly recognized as an excellent model tree for the study of tree growth and its underlying physiology and genetics. By studying trees of the genus Populus (poplars, cottonwoods, aspens), which in their native ecosystems play a major role in the re-colonization of sites after disturbances, new insights have been gained into plantation culture and the development of improved cultivars. Of the 20 chapters in this publication, editored by an international group of researchers, one section deals with systematics, genetics, genetic manipulation and biotic interactions of Populus, while the other deals with stress response and the physiology of growth and productivity" --