Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “regimen”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Projected long-term effects of colorectal cancer screening disruptions following the COVID-19 pandemic

The aftermath of the initial phase of the COVID-19 pandemic may contribute to the widening of disparities in colorectal cancer (CRC) outcomes due to differential disruptions to CRC screening. This comparative microsimulation analysis uses two CISNET CRC models to simulate the impact of ongoing screening disruptions induced by the COVID-19 pandemic on long-term CRC outcomes. We evaluate three channels through which screening was disrupted: delays in screening, regimen switching, and screening discontinuation. The impact of these disruptions on long-term CRC outcomes was measured by the number of life-years lost due to CRC screening disruptions compared to a scenario without any disruptions. While short-term delays in screening of 3–18 months are predicted to result in minor life-years loss, discontinuing screening could result in much more significant reductions in the expected benefits of screening. These results demonstrate that unequal recovery of screening following the pandemic can widen disparities in CRC outcomes and emphasize the importance of ensuring equitable recovery to screening following the pandemic.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1971

Effect of altered 'weight' upon animal tolerance to restraint.

The effect of altered weight upon animal tolerance to restraint was determined by simulating various accelerative forces with directed lead weights using restrained and nonrestrained domestic fowl (chickens). Weighting (increased weight) and conterweighting (reduced weight) produced a stressed condition - reduced relative lymphocyte counts, loss of body mass, and/or the development of a disorientation syndrome - in both restrained and nonrestrained (caged only) birds. The animal's tolerance to altered weight appeared to be a function of its body weight. Unrestrained birds were stressed by counterweighting (mean plus or minus standard error) 58.3 plus or minus 41% of their body weight, whereas restrained birds tolerated only 32.2 plus or minus 2.6% reduction in body weight. A training regimen for restrained birds was not effective in improving their tolerance to a reduced weight environment. It was concluded that domestic fowl living in a weightless (space) environment should be restrained minimally and supported by ventrally directed tension equivalent to approximately 50% of their body mass (their weight in a 1 G environment).

Burton, R. R.↗
NASA NTRS1972

External auditory canal temperature as an estimate of core temperature.

Measurement of rectal (T sub re), auditory canal (T sub ac), positioned 8 to 10 mm from the tympanic membrane, and mean skin temperature (mean T sub sk) in five men during various exercise regimens at an ambient temperature (T sub a) of 25 C (phase one) and in two men during rest and exercise at 5, 15, 25, and 35 C T sub a (phase two). The purpose was to determine if T sub ac can be used as an accurate estimate of core temperature. Previous observations that T sub ac was highly correlated with T sub re but T sub ac was consistently lower than T sub re are confirmed; the mean difference varied from 0.4 C at rest to 1.1 C at the end of exercise. It is concluded that auditory canal temperature cannot be utilized as an estimate of core temperature, but T sub ac may be used to estimate mean body temperature where very accurate measurements are not required.

Greenleaf, J. E.↗
NASA NTRS1972

Thyroid and adrenal cortical rhythmicity during bed rest.

The effects of prolonged bed rest on adrenocortical and thyroid function were assessed in eight healthy males, aged 20-40 years, who were submitted to bed rest for 56 days on a 14L:10D regimen (lights-on, 9:00 AM). Four of these subjects exercised three times daily throughout the experiment. Circulating cortisol, triiodothyronine, and thyroxine, concentrations were determined in blood samples drawn at four hourly intervals for 48-hr periods before, 10, 20, 30, 42, and 54 days during, and 10 days post-bed rest. Significant fluctuations in the circulating levels of all three hormones occurred with peaks at 7:30 AM. The suggestion is advanced that thyroid rhythms may be posture dependent.

Vernikos-Danellis, J.↗
NASA NTRS1973

Evaluation of proposed Skylab and SSP soap products.

Four candidate cleansing agents evaluated in terms of potential hazards to crew members included two soaps (Neutrogena bar soap and Olive Leaf Liquid), one nonfoaming surfactant (Miranol JEM), and one laundry detergent (sodium dodecylbenzene sulfonate). None of the four exhibited adverse dermatological effects from skin patch tests or supported growth of potentially pathogenic microorganisms. Aqueous solutions of Neutrogena did support a mold species. Neutrogena and Miranol JEM were used in a simulated Skylab personal hygiene regimen with no adverse effects on skin or skin microflora. Based on our results, each of these agents appear to be a promising candidate material for the use intended.

Durfee, R. L.↗
NASA NTRS1974

Circadian, endocrine, and metabolic effects of prolonged bedrest: Two 56-day bedrest studies

Two bedrest studies of 56 days each have been conducted to evaluate the effects of prolonged bedrest on circadian synchrony and endocrine and metabolic function. Measurements included the pituitary-adrenal, thyroid, parathyroid, insulin-glucose-growth hormones, catecholamine excretion, body temperature, and heart rate. The results indicated that a rigorous regimen of exercise did not prevent the endocrine and metabolic effects of prolonged bedrest. Changes in circadian, endocrine, and metabolic functions in bedrest appear to be due to changes in hydrostatic pressure and lack of postural cues rather than to inactivity, confinement, or the bleeding schedule. Prolonged bedrest, particularly beyond 24 days, resulted in rhythm desynchronization in spite of well regulated light/dark cycles, temperature, humidity, activity, and meal times and meal composition and in increased lability of all endocrine parameter measured. It also resulted in an apparent insensitivity of the glucose response to insulin, of cortisol secretion to ACTH, and of growth hormone secretion to hypoglycemia.

Vernikos-Danellis, J.↗
NASA NTRS1973

Circadian timing of single daily 'meal' affects survival of mice

It is shown that the survival of young mice after abrupt restriction to a single 4-hr span of daily food accessibility can depend on the temporal placement of this feeding span in relation to the lighting regimen. Housing conditions are an important codeterminant of this response.

Nelson, W.↗
NASA NTRS1974

Circadian rhythmometry of mammalian radiosensitivity

In the case of human bone marrow, the largest number of mitoses is seen in the evening in diurnally active men, mitotic activity being at a minimum in the morning. The opposite pattern is observed for nocturnal animals such as rats and mice on a regimen of light during the daytime alternating with darkness during the night hours. The entirety of these rhythms plays an important role in the organism's responses to environmental stimuli, including its resistance to potentially harmful agents. Conditions under which circadian rhythms can be observed and validated by inferential statistical means are discussed while emphasizing how artifacts of the laboratory environment can be shown to obscure circadian periodic variations in radiosensitivity.

Haus, E.↗
NASA NTRS1974

Medical legacy of Apollo

Since Apollo crews enjoyed freedom of movement and experienced many of the same problems as earlier crews, confinement had to be ruled out in the etiology of space flight-related changes. Apollo was a mission of physiological firsts: the first inflight illnesses were reported, and a series of cardiac arrhythmias occurred. The most important physiological changes were decreased cardiovascular responsiveness, reduced red blood cell mass, and musculoskeletal deterioration. Vestibular-related problems were also noted for the first time. Crewmen lost weight as a result of a hypocaloric regimen inflight and a tendency to lose body tissue under hypogravic conditions. Aldosterone production increased causing some intracellular fluid loss. Very few of the crewmen experienced any psychological problems after Apollo.

Berry, C. A.↗
NASA NTRS1974

Gas exchange and the coagulation system of the blood during the effect on the body of high concentrations of oxygen and carbon dioxide

Maximum permissible concentrations of oxygen and carbon dioxide in a controlled atmosphere were determined by evaluating their effects on human gas exchange, blood coagulation, and tolerances to acute hypoxia, acceleration, and physical loads. It was found that functional disturbances depend on the concentration of respiratory gases and the length of stay in an altered atmosphere. By changing the atmospheric composition and by bringing the gaseous environment into accordance with the work and rest regimen and energy expenditures, the general reactivity of the body changes favorably.

Palosh, L.↗
NASA NTRS1975

Instrumented personal exercise during long-duration space flights

The present work reports the results of instrumented personal exercise performed in flight by Skylab 3 and 4 crewmen. Inflight cycle ergometer data provide conclusive evidence that man can perform earthbound equivalent maximum levels of physical work while in the zero-G environment. Moreover, SL4 crewmen were able to improve their physical condition during 84 days of space flight relative to launch condition, due to rigorous personal exercise regimens. Biological data measured included oxygen consumption, CO2 production, minute volume, and heart rate.

Sawin, C. F.↗
NASA NTRS1975

+Gz tolerance in man after 14-day bedrest periods with isometric and isotonic exercise conditioning

The effects of isometric and isotonic exercise training on post-bedrest +Gz tolerance were determined. In general, 14-day bedrest resulted in a significant loss of Gz tolerance, as previously discovered. At 2.1 Gz, neither the isometric nor the isotonic exercises regimens resulted in a significant increase in post-bedrest Gz tolerance. However, following isometric exercise, restoration of about half the tolerance decrement occurred at 3.2 Gz and 3.8 Gz. Possible reasons for this partial restoration of tolerance are put forward.

Greenleaf, J. E.↗
NASA NTRS1975

Proposed application of lower body negative pressure to cardiology

Potential medical applications are presented of lower body negative pressure to the evaluation and treatment of cardiac patients. The essential features of an LBNP unit and the basic cardiovascular physiology of lower body negative pressure (LBNP) testing are described. Some of the results of previous spaceflight experiences and bedrest studies are summarized. The deconditioning effects of weightlessness experienced by orbiting astronauts are compared with the effects of bedrest restrictions prescribed for convalescing cardiac patients. The potential of LBNP for evaluating both pharmacological and physical activity regimens was examined, particularly in relation to post-myocardial infarction and coronary artery bypass patients. Applications of LBNP to the cardiac catheterization laboratory and the out-patient follow-up of cardiac patients are proposed.

E. V. Schmidt↗
NASA NTRS1975

The application of hydrometeorological data obtained by remote sensing techniques for multipurpose reservoir operations

Watershed snowpack and streamflow data obtained and transmitted by (ERTS) satellite were used in the operational and water management decisions in the Salt River Project. Located in central Arizona, the Project provides water and electric power for the more than 1.1 million residents of the Salt River Valley. The water supply source is a 33,670 square kilometer (13,000 square mile) watershed and 250 deep well pumps. Six storage reservoirs, four of which have hydroelectric capability, located on two river systems have a storage capacity of over 246,600 hectare-meters (2,000,000 AF.). Information from the watershed during the normal runoff period of December to May and more especially during critical periods of high runoff and minimum reservoir storage capacity is necessary for the reservoir operation regimen. Extent of the snowpack, depth of snow, and the condition of the pack were observed in aerial flights over the watershed.

Warskow, W. L.↗
NASA NTRS1975

Program to study optimal protocol for cardiovascular and muscular efficiency

Two possible ways to minimize the effects of deconditioning in space are; To achieve a very high level of conditioning immediately prior to flight, and to provide a regimen in the capsule which will maintain a moderate degree of fitness. It was determined that running and riding a bicycle ergometer at comparable heart rates produced similar gains in physical fitness variables. It was found that subjects who exercised at a 180 heart rate made greater gains in physical fitness than did those exercising at a 140 or 160 heart rate. When the length of the workout was varied, subjects exercising sixty minutes per day made greater gains than those exercising twenty or forty minutes per day. Subjects who discontinued training slowly deconditioned, but a moderate level of fitness could be maintained by exercising at a pulse rate of 160 beats per minute for twenty minute periods three times a week. Subjects who overtrained twice daily to near exhaustion increased in fitness.

Olree, H. D.↗
NASA NTRS1977

Exercise, dietary obesity, and growth in the rat

Experiments were conducted on weanling male rats 35 days old and weighing about 100 g to determine how endurance-type exercise and high-fat diet administered during growth influence body mass and composition. The animals were divided into four weight-matched groups of 25 animals each: group I - high-fat diet, exercised; group II - chow, exercised; group III - high-fat diet, sedentary; and group IV - chow, sedentary. During growth, masses of water, muscle and skin increased as functions of body size; bone as a function of age; and heart, liver, gut, testes, and CNS were affected by combinations of size, age, activity, and diet. Major conclusions are that growth in body size is expressed more precisely with fat-free body mass (FFBM), that late rectilinear growth is probably attributable to fat accretion, and that the observed influences on FFBM of exercise and high-fat diet are obtained only if the regimen is started at or before age 5-7 weeks.

Pitts, G. C.↗
NASA NTRS1976

Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency

A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite rigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 1-1/2 to 3 years duration.

Whedon, G. D.↗