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It is well known that the Baade-Wesselink method leads to different radii for Cepheids depending on which colors are used to determine the effective temperatures. We try to find the reasons for this discrepancy. We employ yet another version of this method using only maximum and minimum radii, thereby circumventing uncertainties in the phase relations between radial velocities and colors. This has essentially no influence on the derived radii. One major uncertainty is the relation between the photospheric expansion velocity and the measured radial velocity. The main reason for the discrepant results obtained by using different colors appears to be an inconsistency in the difference in the applied temperature-color calibrations. Small changes in the d(log Teff)/d(color) can cause major changes in the derived radii.
Spectroscopic diagnostics are used to map key parameters of the cathode fall of a He glow discharge.Optogalvanic spectroscopy on Rydberg atoms is used to perform spatially resolved electric field measurements.The resulting E/N maps provide the ion and electron current densities, which are used to determine the local ionization rates.Local excitation rates are mapped by observing the spectral emission from the discharge.Optogalvanic spectroscopy is also used to observe electron avalanches starting from a well defined position in the cathode fall.These detailed experimental maps will be essential in studies of the nonhydrodynamic electron distribution function.Various theoretical models of the cathode fall will be compared to the experimental results.
Experiments to study the temperature in the discharge produced using a dc spiral hollow cathode with CH4-H2 as the feed gas have been carried out during the rowth of diamond. Optical emission from the R branch of the 3d1 Σ v-O-2p Σ v-O rotational vibronic band are used to determine a rotational temperature. Limitations of this method are discussed.
We have measured the steady state concentration of gas phase C2 in Ar/H2/CH4 and Ar/H2/C60 microwave plasmas used for the deposition of nanocrystalline diamond films. High sensitivity white light absorption spectroscopy is used to monitor the C2 density using the d 3 Π ← a3Π (0,0) vibrational band of C2 as chamber pressure, microwave power, substrate temperature and feed gas mixtures are varied in both chemistries. Understanding how these parameters influence the C2 density in the plasma volume provides insight into discharge mechanisms relevant to the deposition of nanocrystalline diamond.
In our commission the vice-president (VP) becomes the president, and a new VP is chosen from members of the Organizing Committee. The position of secretary was discontinued and its responsibilities incorporated into the VP position. The president announced that the new officers are Steven R. Federman (president) and Glenn M. Wahlgren (vice-president).
The absolute concentration of methyl radicals (CH3) and the mole fraction of acetylene (C2H2) are measured in a hot filament chemical vapor deposition (CVD) system both during and after an initial pretreatment that has been used successfully in microwave plasma and oxyacetylene torch CVD systems to produce more uniform and higher density crystal nucleation. The pretreatment technique, which consists of deposition for a relatively short time with a high input concentration of hydrocarbon in the feed gas, was studied for both methane (CH4) and C2H2 as the input hydrocarbon diluted in H2. Scanning electron micrographs of diamond films deposited under the conditions studied indicate that the pretreatment using CH4 is not effective in increasing the crystal nucleation density, but is moderately effective in increasing the crystal size. The C2H2 pretreatment has no apparent effect upon either the crystal size or nucleation density. The spectroscopie measurements suggest that the surface condition of the filament is the prominent factor affecting the gas phase chemistry both during and after the pretreatment stage.
Prolactin, Cortisol, growth hormone and TSH serum levels (before and 15 minutes after treatment) were measured in 62 patients with endogenous depression randomly allocated to real or pseudo-ECT. Prolactin increased significantly more in those receiving real ECT than in those receiving pseudo-ECT, but the size of this effect had diminished by the time of the last (8th) treatment in the trial. Cortisol secretion was also significantly increased following the first treatment by real ECT, but this increase was of significantly smaller size in patients with delusions. Tolerance to the effects of ECT on Cortisol secretion was not observed. No effects of ECT on growth hormone or TSH secretion were detected, and no clear evidence was obtained that endocrine responses can be used as a predictor of response to ECT.
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