Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

This book (hardcover) is part of the TREDITION CLASSICS. It contains classical literature works from over two thousand years. Most of these titles have been out of print and off the bookstore shelves for decades. The book series is intended to preserve the cultural legacy and to promote the timeless works of classical literature. Readers of a TREDITION CLASSICS book support the mission to save many of the amazing works of world literature from oblivion. With this series, tredition intends to make thousands of international literature classics available in printed format again - worldwide.

This book (hardcover) is part of the TREDITION CLASSICS. It contains classical literature works from over two thousand years. Most of these titles have been out of print and off the bookstore shelves for decades. The book series is intended to preserve the cultural legacy and to promote the timeless works of classical literature. Readers of a TREDITION CLASSICS book support the mission to save many of the amazing works of world literature from oblivion. With this series, tredition intends to make thousands of international literature classics available in printed format again - worldwide.

This book (hardcover) is part of the TREDITION CLASSICS. It contains classical literature works from over two thousand years. Most of these titles have been out of print and off the bookstore shelves for decades. The book series is intended to preserve the cultural legacy and to promote the timeless works of classical literature. Readers of a TREDITION CLASSICS book support the mission to save many of the amazing works of world literature from oblivion. With this series, tredition intends to make thousands of international literature classics available in printed format again - worldwide.

This book (hardcover) is part of the TREDITION CLASSICS. It contains classical literature works from over two thousand years. Most of these titles have been out of print and off the bookstore shelves for decades. The book series is intended to preserve the cultural legacy and to promote the timeless works of classical literature. Readers of a TREDITION CLASSICS book support the mission to save many of the amazing works of world literature from oblivion. With this series, tredition intends to make thousands of international literature classics available in printed format again - worldwide.

This book (hardcover) is part of the TREDITION CLASSICS. It contains classical literature works from over two thousand years. Most of these titles have been out of print and off the bookstore shelves for decades. The book series is intended to preserve the cultural legacy and to promote the timeless works of classical literature. Readers of a TREDITION CLASSICS book support the mission to save many of the amazing works of world literature from oblivion. With this series, tredition intends to make thousands of international literature classics available in printed format again - worldwide.

Chemical fertilizers have had a significant impact on food production in the recent past, and are today an indispensable part of modern agriculture. On the other hand, the oil crisis of the 1970s and the current Middle East problems are constant reminders of the vulnerability of our fossil fuel dependent agriculture. There are vast areas of the developing world where N fertilizers are neither available nor affordable and, in most of these countries, balance of payment problems have resulted in the removal of N fertilizer subsidies. The external costs of environmental degradation and human health far exceed economic concerns. Input efficiency of N fertilizer is one of the lowest and, in turn, contributes substantially to environmental pollution. Nitrate in ground and surface waters and the threat to the stability of the ozone layer from gaseous oxides of nitrogen are major health and environmental concerns. The removal of large quantities of crop produce from the land also depletes soil of its native N reserves. Another concern is the decline in crop yields under continuous use of N fertilizers. These economic, environmental and production considerations dictate that biological alternatives which can augment, and in some cases replace, N fertilizers must be exploited. Long-term sustainability of agricultural systems must rely on the use and effective management of internal resources. The process of biological nitrogen fixation offers and economically attractive and ecologically sound means of reducing external nitrogen input and improving the quality and quantity of internal resources. In this book, we outline sustainability issues that dictate an increased use of biological nitrogen fixation and the constraints on its optimal use in agriculture.

Man has recognised an association of light with life and medicine for over 3000 years. Today the major challenges to this topic include the elucidation of photochemical reactions involved in photobiology at the molecular level. This includes the use of a variety of modem probing techniques that directly measures the reactivity of excited states and free radicals involved in biological reactions. This text-book is based on such an approach and has arisen from some of the lectures delivered at the NATO ASI held at Hotel Capo Caccia near the Centre for Advanced Research in Photobiology (CARP) in Sardegia, Italy. The ASI took place from 30 September -13 October 1993 and involved a total membership of 90. The book, like the NATO ASI itself, is divided into four themes starting with fundamental aspects and ending with complex medically related systems. Thus Theme 1 covers aspects of the underlying photophysics and photochemistry with particular emphasis on modem experimental techniques to study molecular mechanisms of biological processes. Theme 2 applies many of these fundamental studies to the chemical reactions of most relevance to photobiology and photomedicine such as photo-addition, -isomerization, -sensitization and -pigmentation. The third and fourth Themes deal with the deleterious and therapeutic aspects of light with particular emphasis on the use of Photo-Dynamic Therapy (PDT) to treat cancer and on viral and micro bioi infections.

Man has recognised an association of light with life and medicine for over 3000 years. Today the major challenges to this topic include the elucidation of photochemical reactions involved in photobiology at the molecular level. This includes the use of a variety of modem probing techniques that directly measures the reactivity of excited states and free radicals involved in biological reactions. This text-book is based on such an approach and has arisen from some of the lectures delivered at the NATO ASI held at Hotel Capo Caccia near the Centre for Advanced Research in Photobiology (CARP) in Sardegia, Italy. The ASI took place from 30 September -13 October 1993 and involved a total membership of 90. The book, like the NATO ASI itself, is divided into four themes starting with fundamental aspects and ending with complex medically related systems. Thus Theme 1 covers aspects of the underlying photophysics and photochemistry with particular emphasis on modem experimental techniques to study molecular mechanisms of biological processes. Theme 2 applies many of these fundamental studies to the chemical reactions of most relevance to photobiology and photomedicine such as photo-addition, -isomerization, -sensitization and -pigmentation. The third and fourth Themes deal with the deleterious and therapeutic aspects of light with particular emphasis on the use of Photo-Dynamic Therapy (PDT) to treat cancer and on viral and micro bioi infections.

Chemical fertilizers have had a significant impact on food production in the recent past, and are today an indispensable part of modern agriculture. On the other hand, the oil crisis of the 1970s and the current Middle East problems are constant reminders of the vulnerability of our fossil fuel dependent agriculture. There are vast areas of the developing world where N fertilizers are neither available nor affordable and, in most of these countries, balance of payment problems have resulted in the removal of N fertilizer subsidies. The external costs of environmental degradation and human health far exceed economic concerns. Input efficiency of N fertilizer is one of the lowest and, in turn, contributes substantially to environmental pollution. Nitrate in ground and surface waters and the threat to the stability of the ozone layer from gaseous oxides of nitrogen are major health and environmental concerns. The removal of large quantities of crop produce from the land also depletes soil of its native N reserves. Another concern is the decline in crop yields under continuous use of N fertilizers. These economic, environmental and production considerations dictate that biological alternatives which can augment, and in some cases replace, N fertilizers must be exploited. Long-term sustainability of agricultural systems must rely on the use and effective management of internal resources. The process of biological nitrogen fixation offers and economically attractive and ecologically sound means of reducing external nitrogen input and improving the quality and quantity of internal resources. In this book, we outline sustainability issues that dictate an increased use of biological nitrogen fixation and the constraints on its optimal use in agriculture.