For many, the terms aging, maturation and senescence are synonymous and used interchangeably, but they should not be. Whereas senescence represents an endogenously controlled degenerative programme leading to plant or organ death, genetiC aging encompasses a wide array of passive degenerative genetiC processes driven primarily by exogenous factors (Leopold, 1975). Aging is therefore considered a consequence of genetiC lesions that accumulate over time, but by themselves do not necessarily cause death. These lesions are probably made more severe by the increase in size and complexity in trees and their attendant physiology. Thus while the withering of flower petals following pollination can be considered senescence, the loss of viability of stored seeds more clearly represents aging (Norden, 1988). The very recent book "Senescence and Aging in Plants" does not discuss trees, the most dominant group of plants on the earth. Yet both angiospermic and gymnospermic trees also undergo the above phenomena but less is known about them. Do woody plants senesce or do they just age? What is phase change? Is this synonymous with maturation? While it is now becoming recognized that there is no programmed senescence in trees, senescence of their parts, even in gymnosperms (e. g. , needles of temperate conifers las t an average of 3. 5 years), is common; but aging is a readily acknowledged phenomenon. In theory, at least, in the absence of any programmed senescence trees should -live forever, but in practice they do not.

This vivid exposé of corruption and political tyranny in the Dominican Republic rang so true to the reality that the President of that country went on television to denounce the book. Sención's novel follows the lives of three seminary students who suffer from church-state oppression. The book also gives a chilling portrait of Dr. Ramos, a sinister autocrat, who manages to survive six terms as president of his country through manipulation and tyranny.

This volume approaches the history of water in the Iberian Peninsula in a novel way, by linking it to the ongoing international debate on water crisis and solutions to overcome the lack of water in the Mediterranean. What water devices were found? What were the models for these devices? How were they distributed in the villas and monastic enclosures? What impact did hydraulic theoretical knowledge have on these water systems, and how could these systems impact on hydraulic technology? Guided by these questions, this book covers the history of water in the most significant cities, the role of water in landscape transformation, the irrigation systems and water devices in gardens and villas, and, lastly, the theoretical and educational background on water management and hydraulics in the Iberian Peninsula between the sixteenth and the nineteenth centuries. Historiography on water management in the territory that is today Spain has highlighted the region’s role as a mediator between the Islamic masters of water and the Christian world. The history of water in Portugal is less known, and it has been taken for granted that is similar to its neighbour. This book compares two countries that have the same historical roots and, therefore, many similar stories, but at the same time, offers insights into particular aspects of each country. It is recommended for scholars and researchers interested in any field of history of the early modern period and of the nineteenth century, as well as general readers interested in studies on the Iberian Peninsula, since it was the role model for many settlements in South America, Asia and Africa.

During the last 30 years, there has been a remarkable devel opment and increase in the number of processes and devices that utilize or emit non-ionizing radiant energies such as micro waves, a form of electromagnetic wave energy and ultrasound representative of mechanical vibration. These energies are used in all sectors of our society for military, industrial, telecommunications, medical, and consumer applications. More recently, the use of ultrasound in biology and medicine has been considerably expanded. These increases in sources of non ionizing radiant energy have resulted in growing interest on the part of government regulatory agencies, industrial and mili tary physicians, research workers, clinicians, and even environ mentalists. Although there is information on biologic effects and potential hazards to man from exposure to microwaves or ultrasound, considerable confusion and misinformation has permeated not only the public press but also some scientific and technical publications. Interest in the biologic effects of high frequency currents developed in the beginning of the present century. This was followed by the introduction of "u1trashortwave" therapy. During the latter part of World War II, the U. S. military services became interested in the possible hazards to personnel working around microwave sources, and the Office of Naval Research of the U. S. Navy began to sponsor research on the biologic effects of microwaves in 1948. In 1956, the U. S.