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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of cisternal and lumbar cerebrospinal fluid pH in high altitude natives (1975)
    Springer
    Pflügers Archiv 356 (1975), S. 159-167 
    Details
    ISSN: 1432-2013
    Keywords: Acid-Base Balance ; Oxygen Partial Pressure ; Cerebrospinal Fluid ; High Altitude
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Samples of cisternal or lumbar cerebrospinal fluid were obtained from 20 young male volunteers born and living at high altitude (3500 to 4800 m). The pH, carbon dioxide and oxygen tensions, and bicarbonate concentration were measured and compared with those in the arterial and jugular venous blood. A consistent difference between the two CSF compartments was noted, particularly a lower pH (0.05), a higher $$P_{{\text{CO}}_{\text{2}} }$$ (7 Torr), and a lower $$P_{{\text{O}}_{\text{2}} }$$ (7 Torr) at the lumbar site. Mean bicarbonate concentration was not significantly different at the two sites. The main factor is $$P_{{\text{CO}}_{\text{2}} }$$ , which controls the pH variation. These differences were more marked in high-altitude natives than in man at sea level. The existence of a consistent inhomogeneity of CSF acid-base content emphasizes the inaccuracy of using lumbar CSF pH to estimate the ECF pH as regulator of pulmonary ventilation and determinant of cerebral blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584295
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  • 2
    Electronic Resource
    Electronic Resource
    Uptake of noradrenaline in high altitude native's heart (1977)
    Springer
    Cellular and molecular life sciences 33 (1977), S. 739-740 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Uptake of3H-noradrenaline by the heart was studied with sections of isolated atria obtained from high or lowlanders. In native highlanders, affinity for3H-noradrenaline by human atria is more significant than in lowlanders. Furthermore, the Michaelis Menten constant is lower in high altitude native's heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01944162
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  • 3
    Electronic Resource
    Electronic Resource
    La Circulation Cutanée au Cours de l'Adaptation à l'Altitude (1969)
    Springer
    Pflügers Archiv 310 (1969), S. 264-276 
    Details
    ISSN: 1432-2013
    Keywords: Capacitance Vessels ; Cutaneous Circulation ; High Altitude ; Adaptation of Peripheral Circulation ; Kapazitives Handgefäß ; Widerstandsgefäß ; Hautkreislauf ; Höhenphysiologie ; Anpassung des peripheren Kreislaufes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Débit, pression et volume ont été mesurés dans la main droite considérée comme représentative de la circulation cutanée. Ces mesures ont été faites comparativement à basse altitude (50 et 400 m) et à haute altitude (3.750 et 4.800 m), chez des natifs et des transplantés. Les résultats ont montré une élévation concomittente du tonus des vaisseaux résistifs et des vaisseaux capacitifs. Ces changements étaient plus marqués quand la température ambiante était élevée, c'est-à-dire quand la circulation cutanée était importante. De l'extrapolation de ces données à l'ensemble de la circulation cutanée, on peut conclure que cette circulation se comporte comme une réserve de débit (150–200 ml/mm, dans les conditions basales) et de volume (250–300 ml) lors des ajustements circulatoires accompagnant l'hypoxie d'altitude.
    Notes: Summary Blood flow, volume, and venous pressure have been measured in the hand considered as representative of the cutaneous vascular bed. Measurements have been made at low (50 and 400 m) and high altitude (3,750 and 4,800 m) in residents and newcomers. The results showed an increase of the tone of both resistance and capacitance vessels at high altitude. These changes were more marked when the skin temperature was higher, i.e. when the cutaneous circulation was increased. Extrapolating these results to the whole skin area, one could conclude that the cutaneous circulation acts as a blood flow and blood volume reservoir during the circulatory adjustements caused by high altitude hypoxia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587214
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  • 4
    Electronic Resource
    Electronic Resource
    Modeling and experimental study of a transferred arc stabilized with argon and flowing in a controlled-atmosphere chamber filled with argon at atmospheric pressure (1993)
    Springer
    Plasma chemistry and plasma processing 13 (1993), S. 399-432 
    Details
    ISSN: 1572-8986
    Keywords: Transferred arc ; controlled atmosphere ; experiment and modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract For a transferred arc with a flat anode working at atmospheric pressure in an argon atmosphere, the influence of the gas injector design close to the cathode tip has been systematically studied for arc currents below 300 A, gas flowrates between 5 and 60 slm, and anode-cathode distances between 10 and 46 mm. Two types of injector configurations hare been studied: a cylindrical one with its wall parallel to the cathode axis and a conical one with the same cone angle as that of the cathode tip. The arc temperature was measured using flit, absolute intensity of ArI and ArII lines. Beside the roltagc and arc current, the losses at the cathode and at the anode were continuously recorded. An elliptic model was used to calculate the flow velocity, the temperature, and the current density close to the cathode and in the arc column. This model was either laminar or turbulent (K - ɛ), with the empirical constants being functions of the Reynolds nunther of turbulence. A cathode sheath with nonequilibrium conditions was used to obtain accurate cathode boundary conditions. Experiments and modeling hart shown the benefits of using conical injectors which constrict drasfically the plasma_ flow and enhance the gas velocity and the current density, thus increasing the heat flux to the anode. With the cylindrical injector, recirculations close to the cathode lip modify deeply its heating and reduce the plasma jet constriction: velocities and temperatures are lower when the recirculation velocity is higher. This results in lower heat fluxes to the anode compared to the conical injector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01465873
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  • 5
    Electronic Resource
    Electronic Resource
    Velocity measurement of dc plasma jets based on arc root fluctuations (1995)
    Springer
    Plasma chemistry and plasma processing 15 (1995), S. 47-70 
    Details
    ISSN: 1572-8986
    Keywords: Plasma jets ; velocity measurements ; anode arc root fluctuations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The axial component of the radial velocity distribution of a plasma flow generated by a dc plasma spray torch was measured by using a nonintrusive optical method, based on the propagation of the plasma jet luminosity fluctuations. In contrast to the simplicity of the experimental set-up, a special effort was made in the data processing, namely by using numerical techniques defined in the context of signal theory. Both centerline and radial profiles of the axial velocity were obtained for pure Ar and Ar−H2 plasma flows. These experimental results were satisfactorily validated by calculating enthalpy and mass balances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01596681
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  • 6
    Electronic Resource
    Electronic Resource
    Longitudinal changes in body composition, physical capacities and energy expenditure in boys and girls during the onset of puberty (2000)
    Springer
    European journal of nutrition 39 (2000), S. 157-163 
    Details
    ISSN: 1436-6215
    Keywords: Key words Children – puberty – body composition – physical capacities – energy expenditure – whole-body calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Notes: Summary Background: The onset of puberty is a period of rapid anatomical and physiological alterations expected to induce changes in metabolic rate and energy requirements of children. Aim of the study: To evaluate the changes in anthropometrical features, body composition, physical capacities, and energy expenditure (EE) of boys and girls during the period of onset of puberty. Methods: Sixteen children (8 boys and 8 girls were recruited in the same school-class and studied both at 10.4 and 12.8 years of age. Body composition was assessed by bioimpedance analysis. Peak oxygen uptake (peak VO2) was measured using an automated on-line system during exercising on a cycle ergometer. Energy expenditure (EE) was determined by whole-body indirect calorimetry over a 24-h period after a 12-h period of adaptation to the calorimeters. Volunteers followed the same activity programme that included four 15-min periods of exercise. Results: During the onset of puberty, boys and girls gained 4.7±2.1 kg.y−1 (P 〈 0.0003) fat-free mass (FFM), whereas fat mass gain was 1.0±1.2 kg.y−1 (P 〈 0.05) in girls and 0.20±0.66 kg.y−1 in boys (NS). Peak VO2 adjusted for differences in FFM was not significantly affected by gender or pubertal stage. However, adjusted external mechanical power performed at peak VO2 was higher in pubertal than in prepubertal children, by 40% (P 〈 0.0001) and 22% (P 〈 0.003) in boys and girls, respectively. It was also 17% (P 〈 0.0002) higher in pubertal boys than in pubertal girls. Daily and sleeping EE increased by 38% and 32% in boys and girls, respectively, during the 2.4-y period (P 〈 0.0001). Adjusted EEs were also significantly higher in pubertal than in prepubertal boys (P 〈 0.05 and P 〈 0.03), but not in girls. The main significant determinants of daily EE were FFM (r2=0.866, P 〈 0.0001), peak VO2 (r2=0.017, P 〈 0.04), and age (r2=0.014, P 〈 0.05). Tanner's stage was an additional determinant of sleeping EE (r2=0.025, P 〈 0.006). Conclusions: The increases in physical capacities and EE during the onset of puberty indicated clear gender differences, which could be explained mainly by alterations of body composition in boys and girls, and by changes in hormonal status in bouys. They also stressed the significant increase in energy requirements of children, especially boys, at an early stage of puberty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003940070019
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  • 7
    Electronic Resource
    Electronic Resource
    Study of the dynamic and static behavior of de vortex plasma torches: Part II: Well-tye cathode (1995)
    Springer
    Plasma chemistry and plasma processing 15 (1995), S. 257-277 
    Details
    ISSN: 1572-8986
    Keywords: Vortex plasma torch ; arc characteristic ; dimensionless analysis ; electrical measurements ; acoustical measurements ; optical measurements ; signal treatment ; numerical simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This work was devoted to the study of the dynamic and static behavior of de vortex plasma torch with a well-type cathode (power level below 100 kW). The dynamic behavior of the torch was characterized by the fulctuations of arc voltage and current, plasma jet radiation, and acoustic pressure. Characteristic frequencies of the arc root movement inside the torch were observed. By numerical simulation (with the numerical codeMelodie, it was shown that the position of the erosion diameter) of the axial velocity along the cathode channel near the wall. The static behavior of the torch was inverstigated for different cathode designs. The variations of voltage U with arc current I, gas flow rate G nature of the gas and cathode design were represented by semiempirical relationships established between dimensionless numbers. By dimensional analysis, the behavior of this torch was compared with that of two powerful torches: the Aerospatiale and the Plasma Energy Corporation torches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01459699
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of d.c. plasma torch voltage fluctuations (1995)
    Springer
    Plasma chemistry and plasma processing 16 (1995), S. S211 
    Details
    ISSN: 1572-8986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The arc root fluctuations at the anode-nozzle of a d.c. plasma spray torch with a special configuration of the electrodes allowing to work with the same gas flowrate with nozzle diameters ranging from 6 to 10 mm were systematically studied. The plasma gas was Ar/H2 (25 vol % H2), the current was varied between 200 and 600 A and the plasma gas flowrate between 24 and 80 slm. After 30–60 mn working the nozzle wall started to be sufficiently eroded to have a stagnant arc spot which lived until arcing created another one. It was shown that the life time of the upstream arc spots were 30–40 % longer than the downstream ones which could play an important role in the electrode erosion. Dimensional analysis allowed to find a relationship between the nozzle diameter D, the arc current I and gas flow rate G and the mean spot lifetime which is closely connected with the difference between D and the electrical diameter of the arc column. The comparison of voltage signal and light emission at a point of the plasma jet close to the nozzle exit on its axis allowed to determine the mean electrical field within the plasma column and the mean position of the arc root. The comparison with the electrode erosion area for well defined conditions showed a good correlation with the calculated arc root position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01512636
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  • 9
    Electronic Resource
    Electronic Resource
    Velocity Measurements for Arc Jets Produced by a DC Plasma Spray Torch (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 263-283 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasma jet ; plasma torch characterization ; optical diagnostics ; velocity measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract An optical method was used to determine the axial velocity of plasma jets produced by a DC plasma spray torch. Different experimental conditions were tested in order to systematically study the influence of the working parameters on the plasma velocity. In this way, the arc current ranged between 200 and 600 A, the gas flow rate between 30 and 80 slm, and the internal nozzle diameter between 6 and 10 mm; the plasma gases were either an Ar–H 2 mixture or N 2 . Rather well defined tendencies were observed and at the same time it appeared that the arc stability greatly influenced the fluctuations of the velocity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021606701022
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetic modelling of the reduction of SiCl4 in an arc heater for the production of silicon (1982)
    Springer
    Plasma chemistry and plasma processing 2 (1982), S. 399-419 
    Details
    ISSN: 1572-8986
    Keywords: Plasma reduction ; silicon ; modeling and experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The conversion of SiCl4 into Si has been achieved from reduction by a hydrogen plasma produced in an arc heater. As the results (conversion yield about 60%) are far from chemical equilibrium predictions, a kinetic model is proposed using the few kinetic data available in the literature and a temperature history of the reactants deduced from measurements of the temperatures and velocities of the flowing chemical mixture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567565
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