212 resultater (0,29158 sekunder)

Vis alle filtre

Mærke

Butik

Pris (EUR)

Nulstil filter

Produkter
Fra
Butikker

Food Webs and Niche Space - Joel E. Cohen - Bog - Princeton University Press - Plusbog.dk

Food Webs and Niche Space - Joel E. Cohen - Bog - Princeton University Press - Plusbog.dk

What is the minimum dimension of a niche space necessary to represent the overlaps among observed niches? This book presents a new technique for obtaining a partial answer to this elementary question about niche space. The author bases his technique on a relation between the combinatorial structure of food webs and the mathematical theory of interval graphs. Professor Cohen collects more than thirty food webs from the ecological literature and analyzes their statistical and combinatorial properties in detail. As a result, he is able to generalize: within habitats of a certain limited physical and temporal heterogeneity, the overlaps among niches, along their trophic (feeding) dimensions, can be represented in a one-dimensional niche space far more often than would be expected by chance alone and perhaps always. This compatibility has not previously been noticed. It indicates that real food webs fall in a small subset of the mathematically possible food webs. Professor Cohen discusses other apparently new features of real food webs, including the constant ratio of the number of kinds of prey to the number of kinds of predators in food webs that describe a community. In conclusion he discusses possible extensions and limitations of his results and suggests directions for future research.

DKK 493.00
1

Food Webs - Kevin S. Mccann - Bog - Princeton University Press - Plusbog.dk

Food Webs - Kevin S. Mccann - Bog - Princeton University Press - Plusbog.dk

Human impacts are dramatically altering our natural ecosystems but the exact repercussions on ecological sustainability and function remain unclear. As a result, food web theory has experienced a proliferation of research seeking to address these critical areas. Arguing that the various recent and classical food web theories can be looked at collectively and in a highly consistent and testable way, Food Webs synthesizes and reconciles modern and classical perspectives into a general unified theory. Kevin McCann brings together outcomes from population-, community-, and ecosystem-level approaches under the common currency of energy or material fluxes. He shows that these approaches--often studied in isolation--all have the same general implications in terms of population dynamic stability. Specifically, increased fluxes of energy or material tend to destabilize populations, communities, and whole ecosystems. With this understanding, stabilizing structures at different levels of the ecological hierarchy can be identified and any population-, community-, or ecosystem-level structures that mute energy or material flow also stabilize systems dynamics. McCann uses this powerful general framework to discuss the effects of human impact on the stability and sustainability of ecological systems, and he demonstrates that there is clear empirical evidence that the structures supporting ecological systems have been dangerously eroded. Uniting the latest research on food webs with classical theories, this book will be a standard source in the understanding of natural food web functions.

DKK 493.00
1

Food and Drug Legislation in the New Deal - Charles O. Jackson - Bog - Princeton University Press - Plusbog.dk

Food and Drug Legislation in the New Deal - Charles O. Jackson - Bog - Princeton University Press - Plusbog.dk

In June 1938, Franklin D. Roosevelt signed into law a new Food, Drug, and Cosmetic Act, the first major legislation regulating these industries since the 1906 Wiley law. Eliminating many serious and long-standing abuses in production, labeling, and advertising, the 1938 Act was, in the words of David L. Cowen, "a milestone in federal interest in consumer protection." Despite its importance to the American public, however, its passage was effected only after a long, complex battle between conflicting interest groups.This volume is a study in depth of that five-year struggle, fully documented by records, correspondence, and publications, as well as a social history of the period. The author analyzes the inadequacy of the 1906 law, the roles of Franklin Roosevelt, Henry Wallace, and Rexford Tugwell, the American Medical Association, drug associations, and consumers'' and women''s groups.Originally published in 1970.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

DKK 930.00
1

Food and Drug Legislation in the New Deal - Charles O. Jackson - Bog - Princeton University Press - Plusbog.dk

Food and Drug Legislation in the New Deal - Charles O. Jackson - Bog - Princeton University Press - Plusbog.dk

In June 1938, Franklin D. Roosevelt signed into law a new Food, Drug, and Cosmetic Act, the first major legislation regulating these industries since the 1906 Wiley law. Eliminating many serious and long-standing abuses in production, labeling, and advertising, the 1938 Act was, in the words of David L. Cowen, "a milestone in federal interest in consumer protection." Despite its importance to the American public, however, its passage was effected only after a long, complex battle between conflicting interest groups.This volume is a study in depth of that five-year struggle, fully documented by records, correspondence, and publications, as well as a social history of the period. The author analyzes the inadequacy of the 1906 law, the roles of Franklin Roosevelt, Henry Wallace, and Rexford Tugwell, the American Medical Association, drug associations, and consumers'' and women''s groups.Originally published in 1970.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

DKK 404.00
1