Suchergebnisse

A case study of the Denver metropolitan area is presented to document how local governments' responses to fiscal pressure are changing the pattern of land use within metropolitan areas from one of relative specialization within constituent jurisdictions to one of metropolitan complexes composed of communities indistinct in terms of their land use. The discussion illustrates that the trade-offs which exist between fiscal productivity and environmental quality in land use decisions have the potential to compel all but high income residential communities to strive for similar mixes of land use.

This state-of-the-art report includes descriptions of travel aids (Russell's Pathsounder, Kay's ultrasonic spectacles, Benjamin's Laser Cane, and Mims' Seeing Aid), electronic reading machines (the Optacon and the Cognodictor), and vision substitution systems (the research of Collins and of Brindley). The future prospects for sensory aids are discussed in the light of marketing problems, the interest (and disinterest) of large companies in such research, and present levels of funding.

Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity.