Roger Revelle

Height and Weight at Menarche and a Hypothesis of Critical Body Weights and Adolescent Events

Height and weight at menarche were found for each subject in three longitudinal growth studies. Early and late maturing girls have menarche at the same mean weight, but late maturers are taller at menarche. Two other major events of adolescence, initiation of the weight growth spurt and maximum rate of weight gain, also occur at an invariant mean weight. The hypothesis is proposed that a critical body weight may trigger each of these adolescent events. Such an interaction would explain the secular trend to an earlier menarche.

Height and weight at menarche and a hypothesis of menarche

Height and weight at menarche were estimated by interpolation of longitudinal growth data for 181 girls. Mean weight at menarche, about 48 kg, does not change as menarcheal age increases, whereas mean height increases significantly. Early and late menarcheal girls gain the same amount of height, about 22 cm, and the same amount of weight, about 17 kg, in the interval from the initiation of the adolescent spurt to menarche, though late maturers grow at slower rates during the spurt, including the year of menarche. A hypothesis of a direct relation between a critical weight and menarche is proposed. Such an interaction would explain the delaying effect of malnutrition on menarche and the secular trend to an earlier menarche.

Height, weight and age at menarche and the "critical weight" hypothesis.

the observation (1) that both are mutagenic in an Escherichia coli T4 bacteriophage system, make it even more desirable that a persuasive explanation be found for the qualitative difference between them in mutagenicity for Salmonella. ERICH HIRSCHBERG Department of Biochemistry, College of Medicine and Dentistry of New Jersey, Newark 07103 I. BERNARD WEINSTEIN Institute of Cancer Research, Columbia University, New York 10032

Heat Flow through the Deep Sea Floor

Publisher Summary This chapter discusses the heat flow through the deep sea floor. To get an estimate of the heat flow the mean conductivity of the rocks penetrated by a bore hole or shaft must be estimated. Different methods that are employed to measure heat flow at sea are discussed. As on land, the temperature gradient and the conductivity are measured separately, the former by a probe stuck into the sediments of the ocean floor and the latter by laboratory measurements on samples collected with a coring tube. Thermal conductivities are measured by both steady-state and transient methods. The effect of imperfect thermal contact between the specimens and the disks is investigated using disks of varying thickness. The results of measured value of heat flow of three different oceans—Pacific Ocean, Atlantic Ocean, and Mediterranean—are summarized. The oceanic as well as the continental heat flow appears to have its origin below the sediments. If the heat flow at sea is largely brought to the surface by rising convection currents, there should be corresponding regions of low heat flow in places where the material is sinking.

Energy sources for rural development

More energy is needed in the rural areas of developing countries for agriculture, transportation, domestic uses, and industrial development in towns and small cities of the countryside. By the year 2025, rural energy needs in South America, Africa, and Asia, outside the Soviet Union and Japan, could be over 4 TW—half of the present world energy consumption. With known technology most, but not all, of this energy might be supplied by the traditional source of rural energy—the biomass of forest woods and agricultural residues. To obtain a high sustainable yield of biomass, use of some “commercial” energy from fossil fuels or hydroelectric power will usually be necessary. The most serious energy problems will exist in rural Asia, with its high man-land ratios; these are illustrated by the examples of Nepal and Bangladesh. Large capital investments and intensive research and development must be undertaken to ensure adequate future energy supplies for the Asian countries.

Energy dilemmas in Asia: the needs for research and development

Outside of China, the countries of southern and eastern Asia contain 30 percent of the worlds population but only 2 percent of the known fossil fuel resources. Economic growth has resulted in increasing imports of petroleum and petroleum products. Because of the tenfold rise in oil prices since 1972, several of these countries are faced with two dilemmas—one short range and one long range. Unless they can discover more fossil fuel resources within their own borders, they must either incur dangerously growing foreign exchange deficits or drastically slow their economic growth. Research and development in energy production, conversion, and conservation should eventually allow local energy sources, of which the most promising is biomass energy, to be substituted for imported fuels. But diverting scarce land and water to plantations of fast-growing trees or other kinds of biomass may seriously limit food production in these crowded countries.

BARITE CONCRETIONS FROM THE OCEAN FLOOR

In 1938, a dredging from the sea floor off California recovered about 6 kilograms of tubular, sub-spherical, flat, and irregular shaped barite concretions embedded in marine mud. These are poorly sorted in weight and size. They range from 1 to 25 centimeters in length. The physical, chemical, and mineralogical characteristics of the nodules are described and compared with those of other barite concretions found on land or dredged from the sea floor. Barium sulphate is present in amounts up to 77 per cent, in the form of small radial aggregates often within the tests of Pliocene Foraminifera. Various theories of the origin of barite concretions are discussed and tested in terms of those characteristics which seem to be of genetic importance. It is believed that the most probable mode of origin was the interaction of interstitial sulphate-rich sea water of the sediment with ascending magmatic waters containing dissolved barium and strontium. Various bits of evidence suggest that the two other reported occurrences of barite concretions on the sea floor had a similar origin.

Physico-Chemical Factors Affecting the Solubility of Calcium Carbonate in Sea Water

ABSTRACT Recent investigations of the relationships between the various forms of carbonic and boric acids in sea water have made it possible to delimit experimentally the solubility of calcium carbonate in the sea and to estimate quantitatively the relative effects on the solubility of variations in salinity, temperature, hydrostatic pressure, and carbon dioxide content. Although the experimental results obtained by various workers for the solubility product are not in agreement, it is at least certain that surface sea water at a temperature of 30° C is saturated with calcium carbonate. A table is presented showing the comparative effects on the solubility of changes in salinity, temperature, depth, and carbon dioxide content. It is shown that ex. except for water in equilibrium with the a mosphere the most important factor controlling the solubility of CaCO3 in sea water is the CO2 content of the water, which, in turn, is chiefly dependent upon the nature and amount of biological activity. The order of importance of the other factors is temperature, salinity, and hydrostatic pressure. For water in equilibrium with the atmosphere, a condition probably only rarely attained, changes in temperature have the greatest effect on the solubility.

The Oceanographic and How It Grew

Fifty years is a mighty long time in the life of an individual, but a short time in the life of an institution, hardly enough for it to reach young institution-hood. Although the Woods Hole Oceanographic Institution is celebrating its Fiftieth Birthday, I cannot think of it as being 50 years old-rather it is 50 years young. It is still youthful, still changing, still filled with hopefulness for the future. The people who give it life and meaning are as eager as they have always been to meet new challenges, to find new ways to serve the twin causes of understanding and using the oceans. Nevertheless, we can all be thankful that the Woods Hole Oceanographic Institution was born 50 years ago. During most of the intervening years, from 1930 until today, it would have been necessary to invent it if it had not already existed.

Carbon Dioxide and Other Greenhouse Gases in Ocean, Atmosphere, and Biosphere, and Future Climatic Impacts

Publisher Summary This chapter discusses the recent anthropogenic changes in carbon dioxide and other radiatively active gases. The concentration of carbon dioxide in the earths atmosphere is about 340 ppm in volume; it is increasing at a rate in excess of 1 ppmv/year. By the latter half of the next century, atmospheric carbon dioxide could be more than 600 ppmv, which is double the pre-industrial values. Three-dimensional, general circulation models of the atmosphere indicate that because of various feedback effects, the rise in atmospheric carbon dioxide will probably result in an increase in the earths average surface temperature of 2–3°C. The warming will be much greater at high latitudes, possibly 9°C in arctic regions during the wintertime. Other greenhouse gases—such as methane, nitrous oxide, and chlorofluorocarbons—are also increasing in the atmosphere at about the same percentage rate as carbon dioxide. This can cause a further rise in temperature, which can be of the same order of magnitude as the carbon dioxide–induced increase.