Showing papers in "American Scientist in 1978"

The rings of Saturn

Abstract: Consideration is given to the development of theories concerning the rings of Saturn. Particular attention is given to ring structure, noting its thinness, the separations between rings, and observed variations in brightness. Data gathered via infrared, radio and radar techniques are described in terms of ring particle composition and size. Hypotheses about ring origin and evolution are outlined, including the tidal disruption model, calculations of Saturn's gravitational contraction history, grazing, and meteoroid bombardment. Prospects for future observations of Saturn's rings are reviewed, such as the variation in their radar reflectivity as a function of the tilt of the ring plane.

Cotton versus Polyester

Abstract: The energy requirements for the production of fibers, for the manufacture of cloth and clothing items, i.e., a shirt, for the maintenance of the finished product by washing, drying, and ironing, and for replacement due to wear, i.e., the comparative durability, of cotton clothing and clothing made from polyester or polyester--cotton blends, are compared giving details for the energy requirements at each step. It is shown that: the production of cotton fibers requires less energy than the production of polyester, nylon, or acrylic fibers, but that more energy is consumed in the weaving of cotton and cotton blend materials than in that of 100% polyester material, and that 100% polyester materials require the least energy for cleaning and maintenance. Side effects such as land use for cotton cultivation and raw material available for polyester production are also discussed. It is concluded that the higher the polyester content in a shirt, the lower the total energy cost for manufacture and maintenance through 50 cycles of wear and cleaning, and that 20 times as much energy, all from nonrenewable resources, is consumed in the manufacture and maintenance of a cotton shirt as is used in the production of raw cotton fiber. Itmore » is suggested that the energy consumption for the production and use of many modern products needs similar careful examination. (LCL)« less

Nucleosomes: the structural quantum in chromosomes

Abstract: The role of the nucleosome in the packaging of DNA within the cell nucleus is discussed. The DNA of eukaryotic cells is organized into a repeating array of nucleohistone particles called nucleosomes. These chromatin subunits are close-packed into higher-order fibers and are modified during chromosome expression. The structure of the nucleosome is described. Diagrams are included. (RJC)

Protein-calorie malnutrition.

Abstract: essentials of the relevant legislation, naturally finds a major place in the Director-General's report. Pondering on it provokes a second major reflection not so much of a cliche this time expressed in the Director-Genera!'s own words: The evolution of a new system of medical benefits through a process of investigation and debate highlights a significant aspect of contemporary health adminiBtration. This is that, both in the fields of health benefits and social medicine, decisions are arrived at and programmes administered in a continual fiux of debate about aims and methods.

Gamma-ray astronomy and the origin of cosmic rays

Abstract: New surveys of galactic gamma ray emission together with millimeter wave radio surveys indicated that cosmic rays were produced as the result of supernova explosions in our galaxy with the most intense production occurring in a Great Galactic Ring about 35,000 light years in diameter where supernova remnants and pulsars were concentrated.