Showing papers by "Ames Research Center published in 1968"
01 Jun 1968
TL;DR: Voigt profile closed form empirical approximation, showing accuracy and radiant energy transport calculations fitting to curves of growth as discussed by the authors, is used to estimate the energy transport of a growing organism.
Abstract: Voigt profile closed form empirical approximation, showing accuracy and radiant energy transport calculations fitting to curves of growth
470 citations
TL;DR: In this paper, a closed-form approximation to the Voigt profile was developed from an examination of the analysis of Voigts profile calculations, which was used for radiant energy transport calculations.
Abstract: A closed-form approximation to the Voigt profile is developed from an examination of Voigt profile calculations. This approximation matches the Voigt profile within 5 per cent at worst and is generally within 3 per cent or less. In radiant energy transport calculations this approximation is shown to closely reproduce the curves of growth given by use of the Voigt profile expression.
421 citations
TL;DR: Determinations of the salt sensitivity of enzymes extracted from the halophilic alga Dunaliella viridis revealed that pentose phosphate isomersase, ribulose diphosphate carboxylase, glucose-6-phosphate dehydrogenase, and phosphohexose isomerase were inhibited by NaCl concentrations far lower than that in the growth medium.
Abstract: Determinations of the salt sensitivity of enzymes extracted from the halophilic alga Dunaliella viridis revealed that pentose phosphate isomerase, ribulose diphosphate carboxylase, glucose-6-phosphate dehydrogenase, and phosphohexose isomerase were inhibited by NaCl concentrations far lower than that in the growth medium (3.75 m). The inhibition was reversible and was not prevented by preparing the extracts in the presence of salt. Potassium, lithium, and cesium chlorides were equally inhibitory. In contrast, whole cells require rather high levels of NaCl for optimal growth, whereas growth is inhibited by low levels of the other cations. The results suggest a specific mechanism for the exclusion of sodium from the interior of the cell. Images
253 citations
01 Apr 1968
TL;DR: Randomdec as discussed by the authors is a measuring device that provides continuous on-line signatures representative of system free vibration curve and selected points on the curve are used in control and failure detection systems, applied to both linear and nonlinear systems under nonstationary vibratory states.
Abstract: Measuring device, Randomdec, provides continuous on-line signatures representative of system free vibration curve. Selected points on curve are used in control and failure detection systems. Apparatus applied to both linear and nonlinear systems under nonstationary vibratory states.
158 citations
TL;DR: Its application to the thoracic aortas of 18 mature mongrel dogs anesthetized with pentobarbital has shown that dispersion and attenuation data for frequencies between 40 and 200 cps can be obtained without requiring either Fourier transform computations or resolution of reflection interference.
Abstract: Elastic behavior of large blood vessels in canine aorta by measuring dispersion and attenuation of artificially induced pressure waves
147 citations
TL;DR: In this paper, the authors measured the thickness distribution at Lunar Orbiter sites, correlating thickness directly with cratering density, and showed that the thickness directly correlates with crater density.
136 citations
TL;DR: Analysis and design of model follower control system by state space techniques, giving testing procedure and description of testing procedure.
Abstract: Analysis and design of model follower control system by state space techniques, giving testing procedure
125 citations
TL;DR: Improved lithium-drifted silicon solid-state detectors allow detection and energy dispersion of x-rays of about 3 to 30 kiloelectron volts in the electron-microprobe x-ray analyzer.
Abstract: Improved lithium-drifted silicon solid-state detectors allow detection and energy dispersion of x-rays of about 3 to 30 kiloelectron volts in the electron-microprobe x-ray analyzer. Energy resolution is sufficient to separate peaks of characteristic x-rays of elements adjacent in the periodic system at atomic number 20 and higher. The detected x-ray spectrum emitted from an unknown sample can be recorded with a multichannel analyzer in approximately 60 seconds.
120 citations
TL;DR: Dipeptidyl arylamidase II of the anterior pituitary gland has been extensively purified by means of (NH4)2SO4 fractionation, isoelectric precipitation, chromatography on diethylaminoethyl cellulose and IRC-50, and gel filtration on Sephadex G-200.
109 citations
TL;DR: Cations were exceptionally inhibitory to the hydrolysis of Lys-Ala-β-naphthylamide by dipeptidyl arylamidase II, and the sensitivity of the enzyme increased with the size of the cation: Li+ l Na+ l K+ l Tris l puromycin aminonucleoside l puroniccin.
108 citations
TL;DR: Prebiotic genesis of porphyrin synthesized under electric discharge conditions in methane ammonia water systems under methane ammonia drinking water systems is studied.
Abstract: Prebiotic genesis of porphyrin synthesized under electric discharge conditions in methane ammonia water systems
TL;DR: In this article, it was shown that the time interval of early heating in the solar system was short in comparison with the total age of solid matter, and the fast heating process has been attributed to radiogenic matter of short half life.
Abstract: SEVERAL lines of evidence suggest that the time interval of early heating in the solar system was short in comparison with the total age of solid matter. The fast heating process has been attributed to radiogenic matter of short half life. Urey was the first to point out the possible significance of 26Al in this respect1, but certain difficulties eventually led him to question this hypothesis2. Interest was again aroused with Reynolds's discovery3,4 of radiogenic daughter 129Xe and, together with 244Pu fission tracks5, this attests to the presence of short-lived sources of radiogenic heat in the protosolar nebula. Fish, Goles and Anders have studied the hypothesis of extinct radionuclide heating in great detail and have provided specific estimates of the required nuclide concentration for melting and differentiation6.
TL;DR: A method has been developed to determine the phase velocities and damping of sinusoidal axial waves in the carotid artery of anesthetized dogs with the aid of an electro-optical tracking system and appears to be more elastic in the axial than in the circumferential direction.
TL;DR: Phosphorylation on the Primitive Earth: Phosphorylations of Adenosine with Linear Polyphosphate Salts in Aqueous Solution shows positive results for phosphorylation of adenosine in the presence of phosphorous-containing materials.
Abstract: Phosphorylation of adenosine by linear polyphosphate salts in heated aqueous solutions under prebiogenic conditions, discussing adenosine phosphates isomeric composition
TL;DR: A solar wind induced planetary magnetic field system supportable by bodies free of electrically insulating atmospheres and dynamo driven intrinsic magnetic fields was proposed in this paper, with the goal of supporting solar wind-induced planetary magnetic fields.
TL;DR: Room temperature and liquid nitrogen difference spectra of H. cutirubrum extracts show evidence of two b-type, two c- type, and one a-type cytochrome, and a scheme for electron transport involving these components is suggested whereby at pH 7.2 the electron flow proceeds through cy tochrome b(559), eytochrome c(555), and cyto chrome a(592).
TL;DR: The shape of the shock front produced in the solar wind by the plasma from highly geo-effective solar events is determined in this paper, based on an analysis of data on the size of the sudden commencements of geomagnetic storms.
TL;DR: Stagnation point convective heat transfer in frozen boundary layers to surfaces having widely differing catalytic activity in ionized flows is studied in this paper, where the authors show that it is possible to transfer heat from a frozen boundary layer to surfaces with different catalytic activities.
Abstract: Stagnation point convective heat transfer in frozen boundary layers to surfaces having widely differing catalytic activity in ionized flows
TL;DR: In this article, three-dimensional boundary layers on helicopter rotors in forward flight are analyzed within the framework of small-crossflow and quasi-steady approximations; these two assumptions are shown to be mutually consistent and to have a wide range of applicability.
Abstract: Several examples of three-dimensi onal boundary layers on helicopter rotors in forward flight are analyzed within the framework of small-crossflow and quasi-steady approximations; these two assumptions are shown to be mutually consistent and to have a wide range of applicability. In laminar flow, the crossflow can be separated into components due to rotation and due to the instantaneous yawing of the rotor blade relative to the direction of flight. Third-order perturbation expansions for a flat-plate blade show the relative importance of the rotational and translational motion, and analysis of the flow over several blade sections with thickness demonstrates the role of chord wise pressure gradients. The results indicate that the crossflow generally tends to delay separation on the retreating side of the rotor disk. The effects of rotation can be large in regions of incipient separation, but elsewhere the boundary layer generally resembles the viscous flow over a swept wing. Also, the detailed structure of the crossflow depends upon whether the primary flow is accelerating or decelerating.
01 Mar 1968
TL;DR: Chemical studies of life origin, discussing chemical and biological evolution, precellular organization and synthesis of various life compounds, and the role of mitochondria in this evolution.
Abstract: Chemical studies of life origin, discussing chemical and biological evolution, precellular organization and synthesis of various life compounds
TL;DR: In this paper, the thermochemical state and the total stream enthalpy of are-heated gases expanding from reservoir pressures less than 0.5 atm were investigated, where the flow was found to be in equilibrium at the arc-heater exit, and the chemical composition was frozen in the reservoir and nozzle.
Abstract: The thermochemical state and the total stream enthalpy of are-heated gases expanding from reservoir pressures less than 0.5 atm were investigated. The flow was found to be in equilibrium at the arc-heater exit, and the chemical composition was frozen in the reservoir and nozzle. The total enthalpy of the inviscid core of the freejet was determined by three independent methods, and the values obtained by each method are compared. It is shown that if the chemical state of the flow is known, the enthalpy can be determined quite easily by the frozen sonic flow method. The chemical composition of the frozen flow was determined with an energy balance on the arc heater. The total enthalpy was also determined with stream enthalpy profiles and convective heating-rate measurements. When the calorimeters used to measure the heating rate were assumed to be fully catalytic, the enthalpy determined from these measurements and a heat-transfer theory were low by about 40%. This difference can be accounted for with the nonequilibrium theory. However, because of the complex relationship between heating rate and enthalpy for the nonequilibrium flows, the uncertainty of the surface reactivity, and the unknown effects of vorticity interaction on heat transfer, the heating-rate method is not recommended for determining the stream enthalpy in low-density flow. A = area of test model surface on which heating rates were measured; also, cross-sectional area in nozzle, m2 A* = cross-sectional area of nozzle throat, m2 C = defined by Eq. (8) c = mass fraction of dissociated species Cp = total specific heat, Mjoule/kg °K E = voltage, V F(T) = defined by Eq. (7) H = total enthalpy, (u^/2) + h, Mjoule/kg H$_ = total enthalpy at stream centerline, Mjoule/kg #T° = heat content at temperature T, Mjoule/kg ~Hhr = defined by Eq. (2), Mjoule/kg Hne = defined by Eq. (4), Mjoule/kg Hrn = defined by Eq. (3), Mjoule/kg AHf,T° = standard heat of formation at temperature T, Mjoule/kg h = static enthalpy, Mjoule/kg h° = heat of recombination, Mjoule/kg I = current, amp K = constant in Eq. (14), kwkg/Mjoule-m3/2 atm 1/2
TL;DR: Conditions can be created in which inorganic phosphates act as phosphorylating agents and these reactions may have occurred in prebiotic chemical processes.
Abstract: Prebiotic chemical reactions on primitive earth in evolution of life, discussing phosphorylation of nucleosides with phosphoric acid and monobasic salts
TL;DR: These results show better agreement than was previously suggested by workers utilizing other indicator-dilution systems, and Reasons for this finding, such as the fact that studies were carried out in quick succession in the same patients, the advantage of indocyanine green over other indicators, the characteristics of the fiberoptic sampling system, the adequacy of mixing in the human left ventricle, and the errors inherent in the angiocardiographic method are discussed.
Abstract: End-diastolic volumes, stroke volumes, and ejection fractions determined in quick succession by the fiberoptic indicator-dilution technique and the angiocardiographic method were compared in 63 patients with various disorders, aged 6 weeks to 58 years. The calibration methods are discussed in detail. Good agreement was found (r=0.965) although end-diastolic volume by the fiberoptic-indicator method (FO) (mean, 106.3 ml/m 2 ) consistently exceeded enddiastolic volume by the angiocardiographic method (A) (92.5 ml/m 2 ). Variations in injection techniques, the absolute size of the volume (range, 31.0 to 478.5 ml/m 2 ), and heart rate (from 55 to 179 beats/min) did not influence this correspondence significantly. Stroke volumes, ejection fractions, and end-systolic volumes were compared in 41 patients with nonregurgitant lesions. The correlation coefficients are 0.808, 0.824, and 0.950, respectively. These results show better agreement than was previously suggested by workers utilizing other indicator-dilution systems. Reasons for this finding, such as the fact that studies were carried out in quick succession in the same patients, the advantage of indocyanine green over other indicators, the characteristics of the fiberoptic sampling system, the adequacy of mixing in the human left ventricle, and the errors inherent in the angiocardiographic method are discussed. Since agreement existed over a wide range of volumes, a set of regression equations was calculated that permitted the interchange of stroke volume, ejection fraction, and end-systolic and end-diastolic volumes in situations where one technique is favored over the other. Thus, for end-diastolic volume by angiocardiography, EDV A =0.785 EDV FO + 10.6 (in ml/m 2 ).
TL;DR: Pioneer 6 observations of steady state magnetosheath during transit of magnetopause under quiet solar wind-geomagnetic field interaction conditions were reported in this paper, showing that the magnetoheath was stable during the transit of magnetic field.
TL;DR: Flow characteristics and wall heat transfer in separated flow region of annular cavity at free stream hypersonic speed and high gas temperature were analyzed in this article, showing that the wall heat transferred with the flow characteristics and separated flow regions.
Abstract: Flow characteristics and wall heat transfer in separated flow region of annular cavity at free stream hypersonic speed and high gas temperature
TL;DR: Magnetic field structure associated with coronal streamers observed during solar eclipse of May 30, 1965 as mentioned in this paper was used to detect coronal streams during the 1965 solar eclipse in the US.
Abstract: Magnetic field structure associated with coronal streamers observed during solar eclipse of May 30, 1965
TL;DR: It is concluded that the effects of caffeine and theophylline on the pituitary stress response could be attributed to their inhibition of the phosphodiesterase activity in that tissue.
Abstract: SummaryThis study was undertaken to substantiate the thesis that the potentiation of the stress-induced secretion of ACTH by the methyl xanthines is due to their ability to inhibit the 3′5′-cyclic nucleotide phosphodiesterase. The effect of various drugs on the phosphodiesterase activity of the anterior pituitary, median eminence, brain cortex, and heart of rats was determined both in vitro and in vivo. Incubation of homogenates with caffeine and theophylline markedly reduced the phosphodiesterase activity in all tissues studied except heart, which showed a significant reduction only in the presence of theophylline. In contrast, pretreating the animals with a single dose of caffeine or theophylline reduced the enzyme activity of the anterior pituitary only, and caffeine was more effective than theophylline. Adrenalectomy, chronic or acute administration of hydrocortisone, or incubation of tissue homogenates with hydrocortisone or dexamethasone did not alter the phosphodiesterase activity of the tissues st...
01 Mar 1968
TL;DR: It was concluded that the lung passed well only the low-frequency components of the applied input and that in a vertical lung only about 30% of the mean to peak pressure pulse would be transmitted down to the small vessels and therefore affect the distribution of blood flow.
Abstract: A horizontal isolated lung preparation has been used to examine the transmission of pulsatile blood pressure and flow. Arterial and venous pressure and flows were measured with pressure transducers and electromagnetic flowmeters. After a sudden increase in pulmonary arterial pressure, delays of several seconds were observed before venous flow began to increase. Flow then increased slowly over a period of 1 to 9 seconds to a new steady level. The transmission of pulsatile flow was independent of the outlet pressure and identical for perfusion in the forward and reverse directions. Flow transmission fell from about 75% at a frequency of 0.03 cps to approximately 10% at a frequency of 1 cps. Pressure transmission down to the collapsible vessels was measured when alveolar pressure exceeded venous pressure. At 0.1 cps approximately 50% of the incident pressure wave was transmitted, and at 1 cps this was reduced to 30%. It was concluded that the lung passed well only the low-frequency components of the applied input and that in a vertical lung only about 30% of the mean to peak pressure pulse would be transmitted down to the small vessels and therefore affect the distribution of blood flow.
TL;DR: In this paper, two Ss were presented with a series of near threshold flashes of light and instructed to report for each flash in which of eight different positions it appeared, and the degree to which they were certain about this judgment.
Abstract: Two Ss were presented with a series of near threshold flashes of light and instructed to report for each flash in which of eight different positions it appeared, and the degree to which they were certain about this judgment. Average evoked potentials to the flashes were also recorded from the occiput. A positive-going wave with latency to the peak of 250 msec appeared when the S was certain about his judgment, whether or not he was correct.