Professor Arthur T. Johnson
Respir. Care 56(7):969 –975, 2011
Derya C. Coursey
Steven M. Scharf
Arthur T. Johnson
ABSTRACT
BACKGROUND: Expiratory isovolume pressure-flow curves allow determination of flow limitation and airway resistance, but obtaining an isovolume pressure-flow curve requires placing an esophageal balloon. The stop-flow method of obtaining isovolume pressure-flow curves is easy and noninvasive. OBJECTIVE: To compare the stop-flow and esophageal-balloon methods by measuring the differences between the pressures and flows at which flow limitation first occurs. METHODS: In 5 healthy subjects we used the esophageal-balloon method and the stop-flow method at 25%, 50%, and 75% of vital capacity (VC), and constructed isovolume pressure-flow curves showing the pressure at which the flow became limited during forced expiration. RESULTS: The mean calculated pleural pressure at flow limitation with the stop-flow method was 2.7 times and 1.6 times that via the esophageal-balloon method at 25% of VC and 50% of VC, respectively. The maximum flow at flow-limitation with the stop-flow technique was 0.7 times and 0.6 times that via the esophageal-balloon method at 25% of VC and 50% of VC, respectively. We also calculated the resistance (the inverse of the slope of the line to the point of flow limitation), but there were large variations in the resistance values, so there was no statistically significant relationship between the stop-flow and esophageal-balloon methods. CONCLUSION: The stop-flow method showed potential to noninvasively obtain isovolume pressure-flow curves.
Biological Engineering 1(4): 281-289, 2008
William H. Scott
Kate R. Mackey
Ken Chu
Frank Koh
Arthur T. Johnson
ABSTRACT
This research project was designed to compare energy expenditures during water-immersion and ambient-air states at three external work rates of 50, 100, and 150 W. Eleven participants were tested on two separate occasions on a bicycle ergometger in water-immersion and ambient-air environments for 3 to 4 min at 50 rpm. Oxygen consumptions and heart rates were monitored continuously throughout both sessions. Perceived exertion was assessed at each work rate during the final 30 s of the sampling period. Water immersion produced higher oxygen consumption values (2.21 ±0.20 vs. 1.00 ±0.14 L min-1 at 50 W; 2.64 ±0.33 vs. 1.45 ±0.12 L min-1 at 100 W; and 2.86 ±0.41 vs. 2.00 ±0.16 L min-1 at 150 W). Heart rates were greater in water (142.70 vs. 97.90 at 50 W; 152.73 vs. 113.14 at 100 W; and 163.82 vs. 135.09 at 150 W). Perceived exertion scores were higher in water (11.7 vs. 8.5 at 50 W; 15.0 vs. 10.6 at 100 W and 17.2 vs. 12.7 at 150 W). Energy expenditure rates were greater in the water-immersion environment (769 vs. 348 W at 50 W; 919 vs. 505 W at 100 W; 995 vs. 696 W at 150 W). It was concluded that at a constant external load, water-immersion produces greater oxygen consumption and heart rate responses compared to values assessed in an ambient-air state. This difference reflects the external load required to move the viscous liquid instead of air.
Keywords: Efficiency, Ergometer, Oxygen consumption, Pedaling.
Perceptual and Motor Skills, 2002, 94, 521-532
William H. Scott, Jr.
Karen M. Coyne
Monique M. Johnson
Christopher G. Lausted
Manjit Sahota
Arthur T. Johnson
ABSTRACT
Summary.--31 college age men and women who consume less than three caffeinated beverages per week agreed to participate as subjects in research on the effects of acute caffeine intake on low intensity task performance. All subjects performed two randomly administered test conditions: (1) caffeine (5 mg/kg) and (2) placebo on separate visits following an initial 1-hr. orientation visit. Subjects were administered the beverage 30 min. prior to performing 12 separate tests assessing basic mathematics, simple response, logical reasoning, hand-eye coordination, and spatial and assembly skills . The Spielberger State Anxiety test was administered immediately after consuming the test beverage and once again at posttest Analysis showed that caffeine did not significantly affect performance on all tests with the exception of the peripheral awareness (hand-eye coordination) test on which performance was higher after ingesting caffeine. The placebo treatment produced no effect on state anxiety, which contrasted with a significant rise in anxiety after caffeine consumption. State anxiety values were significantly greater after caffeine treatment relative to the placebo at pretest, and this difference persisted at posttest These results demonstrated that the dose of caffeine increased scores on state anxiety for individuals who consumed less than three caffeinated beverages weekly but had very little effect on performance of low intensity tasks, except for a hand-eye coordination test involving peripheral awareness. Perhaps longer continuous performance of more demanding tasks would be more sensitive.
Encyclopedia of Environmental Biology Volume I, 1995
Arthur T. Johnson
Patrick Kangas
I. Definitions
II. General Model of Biomass Production
Ill. Applications and Case Studies
ABSTRACT
Biological engineering is that discipline of engineering using or applied to biological systems. An understanding of biology can help engineers address environmental problems, including sustainable production of biomass. To be truly sustainable, utilization of biomass requires a knowledge of ecological interactions in the biomass stages of production, harvesting, and processing.
Journal of Sustainable Agriculture, Vol. 2(4) 1992
Arthur T. Johnson
Geoffrey W. Schoming
John H. Vandersall
Jack W. Wysong
Lester R. Vough
Larry E. Stewart
ABSTRACT
The number of small farms in the U.S. is steadily increasing. Many people with one to ten acres of land own several horses, cattle, sheep, or other animals. These owners need to be served by agricultural systems research just as farmers on large tracts of land. This paper describes a silage system useful for those with small numbers of livestock who ordinarily would purchase most of their winter feed. Studies of the means for making, storing, and feeding the silage were made. The silage was found to be a nutritious feed source except when made from grass mowed from areas near vehicular traffic or from orchards. This system uses steel drums as containers, uses materials and machinery readily available in the industrialized world, requires no indoor storage, and can be fed to animals with a minimum of labor. Animals prefer the silage to average quality hay.
Computer Programs in Biomedicine 19 (1985) 127-130
Arthur T. Johnson
ABSTRACT
Writing programs for use by others is not easy. Above all, one must know the group the program is written for, and try to relate the program to the group.
Computer Programs in Biomedicine 18 (1984) 259-264
Arthur T. Johnson
ABSTRACT
A program written for use with the IBM-PC can be used to find least squares solutions to linearized multidimensional equations. The program is 'user-friendly' by requiring little from the user except to make decisions; most responses can be entered by a single keystroke. Once data are entered by the user, they can be repeatedly manipulated, graphed, and correlated. Many models relating data variables can be tried relatively easily, and best fit results found. Examples using respiratory mechanical data illustrate the ease of model comparisons.
Journal of Food Process Engineering 1 (1977) 241-258
F. J. Feldstein
D. C. Westhoff
R. Kort
A. T. Johnson
ABSTRACT
The suitability of various carton materials for the nonrefrigerated storage of sterilized milk was investigated. One quart paperboard cartons were fabricated from the same base sheet of stock but varied in the type of sizing used to make them resistant to penetration by liquids and whether or not they were aluminum foil-lined. They were preformed and sterilized with ethylene oxide. The four types of paperboard were: (a) rosin (sizing) paperboard (R); (b) rosin paperboard with foil lining (RF); (c) cyanasize (sizing) juice paperboard (CJ); and (d) cyanasize-juice paperboard with foil lining (CJF). Each carton was aseptically filled and sealed, in a glovebox. Incubation was carried out at 20oC for up to nine weeks. Every week five cartons of each type were randomly selected and the milk tested for microbial stability and flavor. The candidate cartons were also tested for degradation of the physical characteristics of static bulge, wicking, tensile strength, and stiffness. Of these, it appears as if selection of carton type will be determined mostly by wicking resistance. The most acceptable carton type is CJF, which had minimal wicking, acceptable bulge, acceptable stiffness, and acceptable tensile strength during the testing period.
Journal of Irreproducible Results, Volume 22(4), 1977
Arthur Johnson
ABSTRACT
Cream of tartar has been used for years as a softening and preserving agent in chocolate fudge (Chaffin, 1973). Despite its apparent advantages, a great deal of evidence weighs against its use. The Food and Drug Administration (FDA), however, has failed to act against the use of cream of tartar in chocolate fudge. Several technical reasons have been advanced to explain the actions of the FDA, but many knowledgeable people suspect political motives to have been the chief factor in the lack of a forthright decision. Since 1952, weighty evidence has been available to the FDA against the use of cream of tartar. This report is intended to present the evidence which has accumulated during the previous two decades of controversy.
AEMB Executive Newsletter, V3(1):6, 1976
Arthur T. Johnson
ABSTRACT
Agriculture is one means by which biology has been harnessed for the good of mankind. Modern production agriculture is a complex, often uncertain technology that requires input from many scientific and engineering disciplines in order to improve its current output capacity. Agribioengineering, the application of engineering to biological problems in agriculture, is a very active and exciting profession characterized by the broad nature of its problems and approaches.