Phenomenological theory of cuprate superconductivity

Reasonably good agreement with the superconducting transitiontemperatures of the cuprate high‐T c superconductors can be obtained on the basis of an approximate phenomenological theory. In this theory, two criteria are used to calculate the superconducting transitiontemperature. One is that the quantum wavelength is of the order of the electron‐pair spacing. The other is that a fraction of the normal carriers exist as Cooper pairs at T c . The resulting simple equation for T c contains only two parameters: the normal carrier density and effective mass. We calculate specific transition temperatures for 12 cuprate superconductors

Anti-sense And Common-sense: Regulation of Food From Genetically Engineered Plants

Genetic engineering technology has recently generated techniques for making specific and precise alterations to the genetic composition of crops grown as food for humans and animals. These advances should facilitate the development of crops with enhanced resistance to diseases, pests and bad weather, improved tolerance of environmentally safer herbicides, and greater nutritional value. However, the very power of these techniques has raised fears of potential ecological catastrophe, as well as religious and aesthetic questions that arise from the prospect of vegetables containing genes ultimately derived from fish and animals. This essay briefly reviews the nature of the technology and its potential benefits and risks. It then discusses the regulatory framework with particular emphasis on the regulatory strategy adopted by FDA. Finally, it suggests that FDA's stance, while legally and scientifically defensible, is strategically misconceived in that stricter regulation would promote public acceptance of this technology

Discovery of near-Earth asteroids by CCD scanning

The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented