HDL-cholesterol levels in the multiple risk factor intervention trial (MRFIT) by the MRFIT Research Group

Preliminary data from the Multiple Risk Factor Intervention Trial (MRFIT) have been examined for evidence that the program has an influence on plasma HDL-cholesterol. The overall mean level of this lipoprotein in the initial cohort of 1,084 men was not altered by two years of participation in this risk factor reduction project. However, changes did occur, both upwards and downwards, in some individuals. There were significant negative associations between change in HDL-cholesterol and changes in body mass, VLDL-cholesterol, LDL-cholesterol, and serum thiocyanate (a measure of cigarette smoking exposure); and there was a small positive association with change in reported alcohol intake. Multiple regression analysis revealed each of these associations to be independent of the others. The fat-controlled diet designed to lower total serum cholesterol did not decrease HDL-cholesterol levels. We conclude that conventional risk reduction programs are not likely to lower circulating HDL-cholesterol, and that program components such as weight reduction and smoking cessation may increase the levels. A listing of investigators follows the text.     

Investigation of antioxidants for polyunsaturated edible oils

The recent trend toward increased use of polyunsaturated vegetable oils in the human diet has emphasized the need for better antioxidant systems than those currently available. This need led to a research program in which a variety of experimental antioxidants were evaluated. Their selection was influenced by general requirements for food additives and by the results of prior antioxidant studies in various fields. Emphasis was placed on hydroxybenzene types, particularly substituted hydroquinones. Oxidative stability tests employing the standard AOM procedure and 110F shelf storage were used to screen the antioxidants in polyunsaturated oils. The type and number of substituent groups on hydroquinone had considerable effect on antioxidant potency. Some of the experimental compounds, such as 4,4′-methylenebis(5-acenaphthenol) and monoalkylhydroquinones, were several times as effective in the test oils as food-approved antioxidants currently available. Presented at the AOCS Meeting, Cincinnati, October, 1965.     

Open & Short Circuit Reliability of Systems of Identical Items

The paper is about reliability and risk analysis of systems of s-identical, s-independent items in terms of their probabilities of failure in open and short circuit. It is importantly assumed that the system is operational while at least one (or as a special case, more) operational item is connected physically to the input and output of the system either directly or through other good or shorted items and there is no overall system short-circuit. Two or more items so connected, whether in physical series or parallel or any combination have the same effect as a single item, and such redundancy does not alter the item failure probabilities. The probabilities could be those arising from identical, s-independent distributions (iid) over a fixed period with fixed starting conditions or alternatively probabilities of failure upon switching on. The work applies therefore to systems of adjustable or self-adjusting items such as amplifiers, rheostats, or fluid control valves, but not, for example, to systems of fixed resistors if the output values of voltage and current are important. Methods are developed for finding the most reliable physical arrangements of 2, 3, 4, items given the item failure probabilities. These display symmetry arising from the equivalence of the reliability block diagrams for items in physical series failing short and items in physical parallel failing open and vice versa. Three or four items are often sufficient to meet reliability requirements.     

Impact of geothermal well testing on exposed vegetation in the Northern Negros Geothermal Project, Philippines

The impact of geothermal fluid discharges during the testing of Pataan 5-D well was evaluated on seedlings of mahogany (Swietenia macrophylla King) at various distances from the well and on natural forest vegetation around the wellpad. The parameters measured were: (1) geothermal brine spray concentration; (2) plant concentration of geothermal signature ions (B, Cl, Li and Na); (3) symptoms of plant damage; and (4) plant recovery. Meteorological parameters were also gathered. Adverse effects on the test plants were observed at distances of 5–50 m from the well silencer for over-spray during the horizontal discharge and at 50–350 m from the wellhead during the vertical discharge. Salinity was identified as a significant cause of plant damage. Observed symptoms of damage included drying of leaf tissues expressed as necrotic areas, which occurred first at the tip of older leaves and progressed along the margins as severity increased, resulting in abnormal defoliation. Recovery of seedlings and natural vegetation from sprays was observed in both vertical and horizontal discharges.     

Strong and auxiliary forms of the semi-Lagrangian method for incompressible flows

We present a review of the semi-Lagrangian method for advection-diffusion and incompressible Navier-Stokes equations discretized with high-order methods. In particular, we compare the strong form where the departure points are computed directly via backwards integration with the auxiliary form where an auxiliary advection equation is solved instead; the latter is also referred to as Operator Integration Factor Splitting (OIFS) scheme. For intermediate size of time steps the auxiliary form is preferrable but for large time steps only the strong form is stable.