Biomedical subjects

C F Theis

Publications and source records attributed to C F Theis.

4 recordsLinked to original sources

PubMed1985

The effects of moisture on molecular sieve oxygen concentrators.

Molecular sieve oxygen generating systems are receiving extensive laboratory and flight evaluation. Assessment of the molecular system has generally been conducted in the laboratory using clean dry air. In aircraft, however, the molecular sieve generator is supplied with engine bleed air which may not always be totally free of contaminants and water. Recent studies using bed washout technics have shown that the molecular sieve units, with 50% of the beds deactivated with water, still function normally with respect to product gas flow and O2 concentration. By utilizing the technics described in this paper, the moisture content or state of hydration of the molecular sieve can readily be determined.

Aerospace Medicine↗

PubMed1982

Comparison of respirator protection factors measured by two quantitative fit test methods.

A comparison of measured respirator protection factors for a di-2-ethylhexyl phthalate (liquid aerosol challenge) respirator quantitative fit test method is made with a complementary sodium chloride (solid aerosol challenge) method. The United States Army XM-29 chemical warfare defense respirator was used in this evaluation. A subject pool of twelve individuals (two female and ten male) were fitted and tested on both respirator quantitative fit test methods on ten different occasions. An exercise protocol of six different breathing and head movement maneuvers was used in each test. The purpose of the comparison was to determine if there is a difference between the two fit test methods. The di-2-ethylhexyl phthalate method showed a significant order-interaction effect with respect to the exercise sequence and whether it preceded or followed testing with sodium chloride. The sodium chloride method did not show a similar phenomenon, and consistently measured smaller protection factors compared to the di-2-ethylhexyl phthalate method. It appears that the sodium chloride method is more sensitive.

Chemical Warfare↗

PubMed1978

A nomogram to predict lean body mass in men.

A simple three scale nomogram is presented to predict lean body mass in men from two anthropometric measurements: height and the circumference of the flexed biceps. The prediction equation used in constructing the nomogram was established from data collected on 198 USAF aircrewmen. Lean body mass was determined on these men by a standard tritium dilution technique. The equation was validated on a total of 65 additional flyers, comparing measurements obtained by tritium dilution (r = 0.91), 40K wholebody counter techniques (r = 0.90), and water-displacement techniques (r = 0.86). A second nomogram demonstrates the flexibility in using this anthropometric-type prediction of body composition to arrive at personalized weight standards.

Adult↗

PubMed1977

Estimations of body composition by various methods.

Body composition was measured in 38 young men all of whom were overweight by standard height-weight tables. The techniques used were body volumetry, determination of total body water by tritium dilution, whole body 40K counting, and anthropometric measurements required for an equation by Wright and Wilmore, the biceps-height formula, and a complex anthropometric model. Body volumeter and total body water dilution results agreed closely. 40K counts gave lower means for the lean mass (higher means for fat mass and percent body fat), while the Wright-Wilmore equation and complex anthropometric model gave high mean values for lean mass (low means for fat mass and percent body fat). Among the five methods correlation coefficients ranged from 0.81 to 0.94 for lean body mass, from 0.74 to 0.89 for fat mass, and from 0.60 to 0.86 for percent body fat. Although all subjects were overweight, only six (16%) were obese.

Anthropometry↗