Showing papers in "Scientific American in 1977"

The Theory of the Rainbow

Abstract: The rainbow is a bridge between the two cultures: poets and scientists alike have long been challenged to describe it. The scientific description is often supposed to be a simple problem in geometrical optics, a problem that was solved long ago and that holds inter­ est today only as a historical exercise. This is not so: a satisfactory quantitative theory of the rainbow has been devel­ oped only in the past few years. More­ over, that theory involves much more than geometrical optics; it draws on all we know of the nature of light. Allow­ ance must be made for wavelike proper­ ties, such as interference, diffraction and polarization, and for particlelike prop­ erties, such as the momentum carried by a beam of light. Some of the most powerful tools of mathematical physics were devised ex­ plicitly to deal with the problem of the rainbow and with closely related prob­ lems. Indeed, the rainbow has served as a touchstone for testing theories of op­ tics. With the more successful of those theories it is now possible to describe the rainbow mathematically, that is, to pre­ dict the distribution of light in the sky. The same methods can also be applied to related phenomena, such as the bright ring of color called the glory, and even to other kinds of rainbows, such as atomic and nuclear ones. Scientific insight has not always been welcomed without reservations. Goethe wrote that Newton's analysis of the rain­ bow's colors would "cripple Nature's heart. " A similar sentiment was ex­ pressed by Charles Lamb and John Keats; at a dinner party in 1817 they proposed a toast: "Newton's health. and confusion to mathematics. " Yet the sci­ entists who have contributed to the the­ ory of the rainbow are by no means in­ sensitive to the rainbow's beauty. In the words of Descartes: "The rainbow is such a remarkable marvel of Nature . . . that I could hardly choose a more suitable example for the application of my method. " The single bright arc seen after a rain shower or in the spray of a waterfall is

Microelectronics and Computer Science

Abstract: The functional architecture of the computer has traditionally been shaped by the size of specialized components and concepts of how people think. Microelectronics is now eliminating these constraints.

The epidemiology of influenza.

Abstract: The epidemiology of influenza swarms with incongruities, incongruities exhaustively detailed by the late British epidemiologist, Edgar Hope-Simpson. He was the first to propose a parsimonious theory explaining why influenza is, as Gregg said, \"seemingly unmindful of traditional infectious disease behavioral patterns.\" Recent discoveries indicate vitamin D upregulates the endogenous antibiotics of innate immunity and suggest that the incongruities explored by Hope-Simpson may be secondary to the epidemiology of vitamin D deficiency. We identify – and attempt to explain – nine influenza conundrums: (1) Why is influenza both seasonal and ubiquitous and where is the virus between epidemics? (2) Why are the epidemics so explosive? (3) Why do they end so abruptly? (4) What explains the frequent coincidental timing of epidemics in countries of similar latitude? (5) Why is the serial interval obscure? (6) Why is the secondary attack rate so low? (7) Why did epidemics in previous ages spread so rapidly, despite the lack of modern transport? (8) Why does experimental inoculation of seronegative humans fail to cause illness in all the volunteers? (9) Why has influenza mortality of the aged not declined as their vaccination rates increased? We review recent discoveries about vitamin D's effects on innate immunity, human studies attempting sick-to-well transmission, naturalistic reports of human transmission, studies of serial interval, secondary attack rates, and relevant animal studies. We hypothesize that two factors explain the nine conundrums: vitamin D's seasonal and population effects on innate immunity, and the presence of a subpopulation of \"good infectors.\" If true, our revision of Edgar Hope-Simpson's theory has profound implications for the prevention of influenza. Introduction It is useful, at times, to question our assumptions. Arguably, the most universally accepted assumption about influenza is that it is a highly infectious virus spread by the sick. Edgar Hope-Simpson not only questioned that assumption, he went much further. Realizing that solar radiation has profound effects on influenza, he added an unidentified \"seasonal stimulus\" to the heart of his radical epidemiological model [1]. Unfortunately, the mechanism of action of the \"seasonal stimulus\" eluded him in life and his theory languished. Nevertheless, he parsimoniously used latent asymptomatic infectors and an uniPublished: 25 February 2008 Virology Journal 2008, 5:29 doi:10.1186/1743-422X-5-29 Received: 9 February 2008 Accepted: 25 February 2008 This article is available from: http://www.virologyj.com/content/5/1/29 © 2008 Cannell et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Virology Journal 2008, 5:29 http://www.virologyj.com/content/5/1/29

The quantum mechanics of black holes.

Abstract: Black holes are described as being able to emit particles from the creation of pairs of quantum mechanical virtual particles of which one falls into the black hole while the other escapes to infinity. Quantum mechanical arguments are used to show that the emitted particles have a thermal spectrum corresponding to a temperature that increases rapidly as the mass of the black hole decreases. (GHT)

Cats and Commerce

Abstract: At first cats would not seem to offer a ..l'l.. likely clue to human history. Yet when one considers that the writ­ ing of adequate histories of human pop­ ulations began scarcely 200 years ago. that writing itself dates back only about 6.000 years and that for many popula­ tions historical. linguistic and cultural records are inadequate or nonexistent. cats appear in a different light. They have been associated with human be­ ings for a long time. but they have never had any economic significance and only rarely have they had much social signifi­ cance. Genetically they. unlike other domesticated animals. have been left largely to themselves. The study of the population genetics of cats is therefore rewarding not only for what it reveals about the evolution of cats but also for what it suggests about the movements of human populations. The study of population genetics has in general become a powerful tool for unraveling human history and prehisto­ ry and particularly for solving problems of the origin and dispersal of plants and animals. Each individual study. how­ ever. brings out limitations in both the organism being investigated and the approach made to the study. To obtain greater precision in the interpretation of complex events it is therefore desirable to study a number of species. Cats would qualify for this reason alone. but they have several advantages in addition to the ones I have already mentioned. One advantage is that cats display vis­ ible polymorphisms. or variable traits. for which the genetic bases are reason­ ably well understood. Most of the poly­ morphisms relate to the color. pattern and texture of the fur and so can be diag­ nosed and recorded at a glance. Hence the accumulation of data is a relatively inexpensive procedure. unencumbered by sophisticated techniques and tech­ nologies. Cats are cosmopolitan. thanks to the exploratory and commercial activity of human beings. The animals have been spread from their homelands in the Old World to every inhabited part of the

Fermat’s Last Theorem

Abstract: Honorable Pierre de Fermat was truthful. He could have squeezed the proof of his last theorem into a page margin. Fermat's last theorem has been proved on a single page. The proof is based on the Pythagorean identity sin cos 2 2 1 θ θ + = . One will first show that if n = 2 . c a b n n n = + holds, followed by showing that if n > 2 (n an integer), c a b n n n = + does not hold. Applying a polar coordinate system, let a b c , ,and be three relatively prime positive integers which are the lengths of the sides of a right triangle, where c is the length of the hypotenuse, and a b and are the lengths of the other two sides. Also, let the acute angle between the hypotenuse and the horizontal be denoted by θ . Three similar versions of the proof are presented. The proof is very simple, and even high school students can learn it. Perhaps, the proof in this paper is the proof that Fermat wished there were enough margin for it in his paper.

The Disposal of Radioactive Wastes from Fission Reactors

Abstract: This article describes the nature of the wastes produced by nuclear power reactors, evaluates their potential impact on public health and the environment, and outlines current plans to dispose of them in secure underground repositories. Arguments against this mode of disposal are answered. (DLC)

The program of fertilization.

Abstract: The eggs of marine invertebrates particularly the echinoderms as sea urchins sand dollars and starfish are used for the study of fertilization. The specific recognition of the egg by the sperm is thought to occur when the sperm makes contact with the jelly coat that surrounds the egg. Substances in the jelly coat interact with the outer membranes of the sperm cell to release digestive enzymes that enable the sperm to dissolve a hole in the layers surrounding the egg so that the sperm can reach the surface of the egg. A single fertilizing sperm enters the egg. Once the sperm has entered the egg its nucleus rotates 180 degrees and migrates toward the nucleus of the egg. About 20 minutes later paternal and maternal nuclei fuse. With the condensation of the chromosomes and the 1st cleavage of the egg fertilization is completed. The fusion of a sperm and an egg triggers a series of transient changes in the concentration of ions that prevent the fusion of additional sperm and initiate development of the embryo. It seems likely that regulation through the transient or permanent modulations of ionic content is widespread in the living world and that mechanisms for regulating cellular acivity at fertilization are utilized throughout the life span of the organism.

Research involving children.

Abstract: When does Human Research involve Children? A study is considered to include children when a person who is under the age of 18 participates in a Human Research study through interaction or intervention with the research team, or collection of a child's identifiable data. Requirements for inclusion of Children in Human Research Investigators must provide protocol specific justification to the IRB, so that the IRB may make a determination that the enrollment of children in the research is justified. • Children are persons who have not attained the legal age for consent to treatments or procedures involved in the research, under the applicable law of the jurisdiction in which the research will be conducted. • Assent means a child's affirmative agreement to participate in research. Mere failure to object should not, absent affirmative agreement, be construed as assent. • Permission means the agreement of parent(s) or guardian to the participation of their child or ward in research. • Parent means a child's biological or adoptive parent. • Guardian means an individual who is authorized under applicable State or local law to consent on behalf of a child to general medical care. • Homeless minor is defined as \" an individual under the age of eighteen years living apart from his parents and who lacks a fixed and regular nighttime residence or whose primary residence is either a supervised shelter designed to provide temporary accommodations, a halfway house or a place not designed for or ordinarily used for sleeping by humans. \" (A.R.S. §44-132(C)) Categories of Research Involving Children There are four (4) categories of research with children permissible under both the Office for Human Research (OHRP) and the Food and Drug Administration (FDA).

An Early Energy Crisis and its Consequences

Abstract: In the 16th century Britain ran out of wood and resorted to coal. The adoption of the new fuel set in motion a chain of events that culminated some two centuries later in the industrial revolution.