Search

A study of the diffuse x-ray reflections from piezoelectrically oscillating quartz and ammonium dihydrogen phosphate (ADP) crystals showed no increase in intensity during oscillation. Quantitative measurements of the intensity increase of the Laue and Bragg reflections during oscillation showed an increase of about 160 percent for the quartz, 7.7 percent for a 0.015 inch thick ADP crystal and 4 percent for a rochelle salt crystal. The intensity increase of Laue reflections for the ADP crystal was shown to be dependent upon its orientation. Since there was no decrease in intensity of the diffuse reflections, it eliminates the possibility that they are the source of the increased energy in the Laue and Bragg reflections.

During the past year the NORELCO Autrometer has been modified with respect to several details. Operation with the helium path and flow counter is now possible for work with the soft elements. Rotation in and out of the loading position is automatic so that all that an operator is required to do is to load the specimen holder. The sample or standard in the reading position can be rotated in its own plane for elimination of diffraction effects and other sample preparation problems. Other modifications in the electronics have increased the reliability and ease of maintenance in the production models, A description will be given of this latest unit and data will be presented on the results obtained both with respect to precision and analytical determinations.

Out-of-class use of technology systems as an aid to self-study is discussed. Four possible systems are described and compared against a proposed set of ideal specifications. The characteristics and advantages of the system using “interactive lectures” are stressed.

I NASMUCH as the frequent persistence of fatigue, drowsiness and languor for a twoto three-week period following anorectal surgery suggested the presence of Iowered potassium levels in certain patients, this study was undertaken to determine the following factors: (I) whether significant changes occur in potassium levels after such surgery, and (2) the effects, if any, of supplying potassium chloride (4 gm. daily) postoperatively, in addition to a potassium-adequate diet.

Excerpt INTRODUCTION The hypothesis that ingestion of excess dietary fat leads to coronary arterial and heart disease is man is supported by much suggestive evidence but has yet to be demonstrated ...

AN OPPORTUNITY to examine the level of total serum cholesterol of Indians residing on five reservations in the United States was afforded when the Public Health Service, in cooperation with the U.S. Department of Interior, conducted the Indian Health Survey from October 1955 through June 1956. Such an examination is of epidemiological initerest, since an early study reported infrequent coronary heart disease among the Navajos which prompted an examination by subsequent investigators (1, 2). They found in a small sample of hospitalized Navajos a low serum cholesterol level when compared with that of a clinic group from the Cleveland population, although the Navajo dietary fat intake apparently was not much less than that of the general diet. These findings are contrary to still inconclusive evidence that a high fat intake is reflected in a high concentration of serum cholesterol in the blood and, perhaps, in an increased tendency to develop atherosclerosis (3, 4). It was theorized from these findings that genetic factors, rather than dietary factors, were the principal cause of the low serum cholesterol level and low coronary heart disease occurrence among the Navajos. Other investigators, in studying different groups of the Navajo population, were not impressed that the Navajo mean serum cholesterol level was particularly low. The,y concluded that the mean level which they observed does not support the hypothesis that the low prevalence of coronary heart disease among the Navajos is a result of low blood lipids (5). It is of particular interest, therefore, to examine the serum cholesterol levels of the American Indians in this survey and to compare these with levels of an American white population having a high mean serum cholesterol level (2). The American Indians who were examined resided on the following reservations: Acoma, N. Mex.; Crow, Mont.; Lac Courte Oreilles, Wis.; San Carlos, Ariz.; and Yankton, S. Dak. The relationship with age was also examined and is presented as additional statistical evidence concerning the level of serum cholesterol of populations (6).