Venus Thermosphere: In situ Composition Measurements, the Temperature Profile, and the Homopause Altitude.

The neutral mass spectrometer on board the Pioneer Venus multiprobe bus measured composition and structral parameters of the dayside Venus upper atmosphere on 9 December 1978. Carbon dioxide and helium number densities were 6 x 10(6) and 5 x 10(6) per cubic centimeter, respectively, at an altitude of 150 kilometers. The mixing ratios of both argon-36 and argon-40 were approximately 80 parts per million at an altitude of 135 kilometers. The exospheric temperature from 160 to 170 kilometers was 285 +/- 10 K. The helium homopause was found at an altitude of about 137 kilometers.

Nitric acid trihydrate (NAT) in polar stratospheric clouds.

A comprehensive investigation of polar stratospheric clouds was performed on 25 January 2000 with instruments onboard a balloon gondola flown from Kiruna, Sweden. Cloud layers were repeatedly encountered at altitudes between 20 and 24 kilometers over a wide range of atmospheric temperatures (185 to 197 kelvin). Particle composition analysis showed that a large fraction of the cloud layers was composed of nitric acid trihydrate (NAT) particles, containing water and nitric acid at a molar ratio of 3:1; this confirmed that these long-sought solid crystals exist well above ice formation temperatures. The presence of NAT particles enhances the potential for chlorine activation with subsequent ozone destruction in polar regions, particularly in early and late winter.

Ruthenium determination in synthetic purex waste solutions by AAS.

A method for the determination of ruthenium in synthetic Purex waste solutions by flame AAS is described. With the usual flames and a lanthanum buffer, only cerium interference in the air-acetylene flame need be considered under the conditions applied. Ruthenium nitrosyl nitrate, ruthenium(IV) hydroxychloride and alkaline ruthenate samples gave identical results, showing that the extraordinarily stable Ru-NO bond does not hinder atomization. The preparation and standardization of the ruthenium nitrosyl solutions, and the alkaline fusion, are briefly described.

Further laboratory studies and stratospheric flight of a mass spectrometer beam system.

A gas expansion system combined with a mass spectrometer has been tested and flown successfully in the stratosphere. Through a sequence of orifices and high speed pumping, gas particles were formed into a molecular beam and analyzed by a sensitive mass spectrometer. During two balloon flights, vertical profiles of all major atmospheric constituents as well as O(3), CO(2), H(2)O and others were obtained. Gases such as (38)Ar and (16)O(17)O provided in-flight calibration standards. The sensitivity of the system was such that gases with mixing ratios of 10 ppb at an ambient pressure of about 10 mbar were detectable.

Small mass spectrometer with extended measurement capabilities at high pressures.

For the in situ investigation of planetary atmospheres a small Mattauch-Herzog mass spectrometer has been developed. Its high-pressure performance has been improved by incorporating differential pumping between the ion source and the analyzing fields, shortening the path-length as well as increasing the extraction field in the ion source. In addition doubly ionized and dissociated ions are used for mass analysis. These measures make possible operation up to 10(-2) millibars. Results of laboratory tests related to linearity, dynamic range, and mass resolution are presented, in particular for CO(2).

[Not Available]. / Technikwissenschaften zwischen theoretischer Erkenntnis und Ingenieurtätigkeit.

In no other scientific field is the conflict between theoretical knowledge and practice so intense as in engineering sciences. The characteristic feature of engineering sciences is that it can neither be classified as "applied science" nor as a part of technology itself. The special position of technological knowledge and its evolution can be illustrated by the example of civil and mechanical engineering. Here special emphasis is given to the close relationship between science, technology and industry, as well as the development of independent research concepts in the engineering sciences.

Can children with spastic cerebral palsy use self-hypnosis to reduce muscle tone? a preliminary study.

A few scattered reports suggest self-hypnosis may be helpful in reducing muscle tone in children with spastic cerebral palsy (CP). These reports are largely anecdotal and offer little objective evidence. This study used the Biocomp 2000 biofeedback electomyogram device to measure the degree of muscle tension in two muscle groups before, during, and after hypnosis in four children with spastic quadriplegic CP. Three of the four children were able to show a very significant decrease in muscle tension while under "trance" and were able to use self-relaxation techniques when confronted with stressful situations. Two of the children also had athetoid or involuntary movements and each was able to better control those movements with the aid of hypnosis. All four children demonstrated improved functional abilities.

Chemical analysis of polar stratospheric cloud particles

A balloon-borne gondola carrying a particle analysis system, a backscatter sonde, and pressure and temperature sensors was launched from Kiruna, Sweden, on 25 January 1998. Measurements within polar stratospheric cloud layers inside the Arctic polar vortex show a close correlation between large backscatter ratios and enhanced particle-related water and nitric acid signals at low temperatures. Periodic structures in the data indicate the presence of lee waves. The H2O/HNO3 molar ratios are consistently found to be above 10 at atmospheric temperatures between 189 and 192 kelvin. Such high ratios indicate ternary solution particles of H2O, HNO3, and H2SO4 rather than the presence of solid hydrates.

Ozone isotope enrichment: isotopomer-specific rate coefficients

Six rate coefficients of relative ozone formation contradict the role of molecular symmetry in the process that results in the enrichment of heavy ozone isotopomers. The results show that collisions between light atoms, such as 16O, and heavy molecules, such as 34O2 and 36O2, have a rate coefficient advantage of about 25 and 50 percent, respectively, over collisions involving heavy atoms and light molecules. These results suggest that the observed isotope effect for each isotopomer may be caused by the preponderance of a single reaction channel and not through molecular symmetry selection.