Evidence for an interplay between cell cycle progression and the initiation of differentiation between life cycle forms of African trypanosomes

Successful transmission of the African trypanosome between the mammalian host blood-stream and the tsetse fly vector involves dramatic alterations in the parasite's morphology and biochemistry. This differentiation through to the tsetse midgut procyclic form is accompanied by re-entry into a proliferative cell cycle. Using a synchronous differentiation model and a variety of markers diagnostic for progress through both differentiation and the cell cycle, we have investigated the interplay between these two processes. Our results implicate a relationship between the trypanosome cell cycle position and the perception of the differentiation signal and demonstrate that irreversible commitment to the differentiation occurs rapidly after induction. Furthermore, we show that re-entry into the cell cycle in the differentiating population is synchronous, and that once initiated, progress through the differentiation pathway can be uncoupled from progress through the cell cycle

Space shuttle: Heat transfer rate measurements on Convair booster (B-15B-2) at nominal Mach number of 8

Plotted and tabulated data on heat transfer from a thin-skin thermocouple are presented. The data is representative of the reentry event of the booster alone configuration. The data were generated during wind tunnel tests of the B-15B-2 delta wing booster at Mach 8. Thermocouple measurements are reduced to heat transfer coefficient ratio and the data are presented as plotted variations versus longitudinal, lateral, and vertical local model positions

The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers

In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation

Ascent heat transfer rate distribution on the North American Rockwell delta wing orbiter and the General Dynamics/Convair booster at a Mach number of 8 (mated)

A wind tunnel test program to determine aerodynamic interference heating on the North American Rockwell orbiter mated with the General Dynamics Convair booster is discussed. The tests were conducted at the Arnold Engineering Development Center (AEDC) in Tunnel B of the von Karman Gas Dynamics Facility (VKF). The test period was June 1971. Heat-transfer rates were determined by the phase-change paint technique on 0.013-scale Stycast models using Tempilaq as the surface temperature indicator. The nominal test conditions were: Mach 8, free-stream unit length Reynolds numbers of 1.25 x one million and 2.55 x one million angles of attack of -5, 0, +5 deg. Model details, test conditions, phase-change paint photographs and reduced heat-transfer coefficients are presented

Space shuttle: Heat transfer rate measurements on Convair booster (B-15B-2) and North American Rockwell orbiter (161B) at nominal Mach number of 8

Plotted and tabulated data from the thin-skin thermocouple phase of an experimental test program are presented. These data are representative of three events of simulated flight and are described as booster-orbiter ascent heating data, booster reentry heating data, and orbiter reentry heating data. The test was conducted in a 50-inch hypersonic tunnel b at a nominal Mach number of 8 and free-stream Reynolds number range of 700,000 to 3,700,000 per foot. The model employed was a 0.009 scale replica of the Convair B-15B-2 booster and North American Rockwell 161B orbiter

Heat transfer test of the McDonnell-Douglas delta wing orbiter and the -17A booster (not mated) at Mach number 8, volume 2

For abstract, see

A Luminous Companion to SGR 1806-20

We have obtained infrared spectra of the star suggested to be the counterpart of the soft gamma-ray repeater (SGR) 1806-20. We found strong emission lines similar to those seen in the spectra of the rare Luminous Blue Variables and B[e] stars. A He I absorption line is also seen, from which we infer a spectral type O9--B2. This classification, in combination with the minimum distance of \simgt6 kpc inferred from its extinction, makes the star one of the most luminous in the Galaxy. We infer that it is a companion to SGR 1806-20, and suggest that the presence of a companion is somehow related to the SGR phenomenon.Comment: 5 pages, AASTEX text+table and 2 PostScript figures (needs LaTeX style files aaspptwo.sty, epsf.sty and rotate.sty). In case of problems, contact [email protected]. Postscript file of complete article available on request. (Replaced because first version had one wrong reference in it

Heat transfer investigation of Langley Research Center transition models at a Mach number of 8, volume 2

The results are presented of a wind tunnel test program to determine aerodynamic heat transfer distributions on delta body and straight body transition models of the space shuttle. Heat transfer rates were determined by the phase-change paint technique on Stycast and RTV models using Tempilag as the surface temperature indicator. The nominal test conditions were: Mach 8, length Reynolds numbers of 5 million and 7.4 million, and angles of attack of 20, 40, and 60 deg. Model details, test conditions, and reduced heat transfer data are included. Data reduction of the phase-change paint photographs was performed by utilizing a new technique