The development is described of an equation to predict the energy cost of treadmill walking of adult males. Oxygen consumption during level walking is considered as the product: oxygen consumption per step · number of steps per minute. At any given speed within the domain of the variable, number of steps per minute is then found to be a reciprocal function of height, and oxygen consumption per step a function of body weight. Rearrangement of the mathematical expressions that describe these relationships permits the calculation of oxygen consumption of level walking as the product of two constants, Pw, a constant for the individual; and Ks, a constant for the speed. It is suggested that these constants may have other uses besides the prediction of oxygen consumption of level walking. Oxygen consumption of grade walking is considered as the excess of oxygen consumption over that observed walking on the level at the same speed. This should be, but apparently is not, simply related to body weight. In a test of its predicting power, the equation predicted the oxygen consumption of 84 treadmill walks of 44 subjects, with a correlation coefficient measured: predicted values, γ = + 0.935. Submitted on October 26, 1962
A rotational temperature comparative study of OH radical vs. N2+ was carried out on a low-power helium microwave-induced plasma. Under the prevailing conditions, N2+ was found to provide twice as many usable lines for temperature measurement than did hydroxyl radical. For the particular torch design used, both species exhibited slightly increasing rotational temperatures at lower flow rates. At fixed conditions, OH consistently indicated higher rotational temperatures than those of the molecular nitrogen ion. Positional studies revealed a slightly increasing temperature near the center of the plasma. This work suggests that N2+ may provide a number of advantages over OH radical as a thermometric probe species in the determination of plasma rotational temperature.
The use of the microwave-induced plasma with a new low-flow plasma centering torch has been evaluated. Data were collected through a computer-controlled, background-correcting polychromator system with two versions of the newly developed laminar flow torch. It showed sensitivities slightly better than the 0.5-mm-i.d. capillary quartz open tube torch. Detection limits were between 8 and 60 pg/s for carbon, hydrogen, bromine, chlorine, and fluorine—a considerably improved performance over the tangential flow torch. Torch lifetime and plasma stability are comparable to or better than the high-flow tangential flow torch with three-hour and three-day RSDs of 2% and 6%. Centered plasmas may be sustained with flow rates as low as 5 mL/min.
Electron number densities were examined in a low-power atmospheric-pressure helium microwave-induced plasma. Two hydrogen-based methods and two helium-based methods were employed to estimate electron concentration. The hydrogen 4471 Å Balmer line was examined with the use of both line shape and full width at half-maximum intensity measurements. The data suggest that half-width calculations underestimate electron densities. Half-width measurements of neutral helium lines result in number densities which appear to be overestimated. This inaccuracy is thought to be the result of apparatus broadening. Finally, the use of quasi-degenerate helium neutral lines possessing forbidden and allowed components afforded electron concentrations similar to those derived from the Balmer beta line shape analysis.
The clasic concept that breathing is regulated only by chemoreceptor mechanisms in the arterial blood stream- the respiratory center, the carotid and aortic bodies-has been modified in two ways. It has been expanded by postulating another chemoreceptor which reacts to the composition of mixed venous blood. It has been qualified by questioning the assumption that the respiratory center has physiologically significant chemosensitivity. (The respiratory center is considered to be, on the contrary, primarily a computing mechanism that integrates information received from chemoreceptors responding to both arterial and mixed venous blood.) By postulating a chemoreceptor mechanism which reacts to the composition of mixed venous blood, a variety of ventilatory responses can be accounted for with a unified and semiquantitative concept based on the ventilatory response to exercise. For the quantitative description of exercise, data obtained from normal men at rest and during exercise have been used to develop several equations which describe the ventilatory response to exercise in terms of P(co)(2) and H(+) of arterial and mixed venous blood. The simplest of these equations, yet a useful one, is the following: V = 1.1 H(+)a + 2.3 Pv(co)(2) - 135 (5a) which states that the volume of breathing is determined by the algebraic summation of influences in arterial and mixed venous blood. Ventilatory responses, as measured in several experimental and clinical situations characterized by acid-base imbalance and associated hyperpnea, have been compared with the ventilation predicted by this equation and by the equation which quantifies Gray's multiple-factor theory. Equation 5a estimated the various ventilatory responses as closely as the multiple-factor theory equation did. Equation 5a was also able to predict ventilation during exercise. It is concluded, therefore, that the hyperpnea of muscular exercise may be a generally applicable expression of the ventilatory response to alterations of the composition of both arterial and mixed venous blood. When applied to the ventilatory responses of cross-perfused animals during exercise, the concept gives a satisfactory qualitative explanation of the various observations. Although there is strong indirect evidence that a chemoreceptor mechanism exists which reacts to the composition of mixed venous blood and whose activity can be quantified, the equations that have been developed are not definitive expressions of the stimuli which regulate breathing. That the equations apply as well as they do, in view of the known errors of fact in their development, is probably the best evidence yet adduced for the essential validity of the present concept.
This study represents the first plasma diagnostic investigation of a laminar flow torch configuration for microwave-induced plasma emission spectroscopy. Spatial intensity profiles indicate that this torch design facilitates the formation of a stable plasma discharge which does not reside on the walls of the plasma containment tube. Spectroscopic temperature determinations were based on the assumption of local thermodynamic equilibrium. Excitation temperatures were found to be several thousand degrees higher than those reported for other low-power He plasmas. Rotational temperature determinations afforded bimodal temperature distributions from the Boltzmann plots, with lower temperature slope regions comparable to values reported by others. Rotational temperatures derived from high-temperature slope regions were several thousand degrees above values obtained in other studies. Temperatures were evaluated as a function of radial position, microwave power, and flow rate.
The electron number density of atmospheric-pressure argon and helium microwave-induced plasmas operating in the power regime of 100 to 450 W has been examined. The resulting data demonstrate a trend of increasing electron density, ne, for both the Ar and He microwave-induced plasmas as forward power is increased. An examination of ne vs. plasma observation position demonstrates a maximum in ne at the central plasma observation position for both plasmas. Further, spatial dependence of electron density appears to be more pronounced at high power levels. Nebulization of aqueous solutions containing varying concentrations of an easily ionizable element into the Ar microwave-induced plasma, MIP, demonstrates little if any effect on ne. Moreover, this observation can be explained by the fact that there is a far greater quantity of water than easily ionizable element being introduced into the plasma in a given time period. Thus the electron contribution resulting from water degradation products in the plasma far outweighs that from the relatively small amount of easily ionizable element present. This last point is further substantiated by an examination of the Ar MIP with and without solution nebulization.
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