An implantable multi-channel temperature transmitter

Implantable multi-channel temperature transmitte

Quantitative measurement by telemetry of ovulation and oviposition in the fowl

Radio telemetry used to determine body temperature cycles in fowl and its relation to ovulation and ovipositio

Circadian, endocrine, and metabolic effects of prolonged bedrest: Two 56-day bedrest studies

Two bedrest studies of 56 days each have been conducted to evaluate the effects of prolonged bedrest on circadian synchrony and endocrine and metabolic function. Measurements included the pituitary-adrenal, thyroid, parathyroid, insulin-glucose-growth hormones, catecholamine excretion, body temperature, and heart rate. The results indicated that a rigorous regimen of exercise did not prevent the endocrine and metabolic effects of prolonged bedrest. Changes in circadian, endocrine, and metabolic functions in bedrest appear to be due to changes in hydrostatic pressure and lack of postural cues rather than to inactivity, confinement, or the bleeding schedule. Prolonged bedrest, particularly beyond 24 days, resulted in rhythm desynchronization in spite of well regulated light/dark cycles, temperature, humidity, activity, and meal times and meal composition and in increased lability of all endocrine parameter measured. It also resulted in an apparent insensitivity of the glucose response to insulin, of cortisol secretion to ACTH, and of growth hormone secretion to hypoglycemia

Element-by-element factorization algorithms for heat conduction

Element-by-element solution strategies are developed for transient heat conduction problems. Results of numerical tests indicate the effectiveness of the procedures proposed. The small database requirements and attractive architectural features of the algorithms suggest considerable potential for solving large scale problems

Space Station Centrifuge: A Requirement for Life Science Research

A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies

Cells in Space

Discussions and presentations addressed three aspects of cell research in space: the suitability of the cell as a subject in microgravity experiments, the requirements for generic flight hardware to support cell research, and the potential for collaboration between academia, industry, and government to develop these studies in space. Synopses are given for the presentations and follow-on discussions at the conference and papers are presented from which the presentations were based. An Executive Summary outlines the recommendations and conclusions generated at the conference

Photometric Identification of Cool White Dwarfs

We investigate the use of a narrow-band DDO51 filter for photometric identification of cool white dwarfs. We report photometric observations of 30 known cool white dwarfs with temperatures ranging from 10,000 K down to very cool temperatures (<3500 K). Follow-up spectroscopic observations of a sample of objects selected using this filter and our photometric observations show that DDO51 filter photometry can help select cool white dwarf candidates for follow-up multi--object spectroscopy by rejecting 65% of main sequence stars with the same broad--band colors as the cool white dwarfs. This technique is not selective enough to efficiently feed single--object spectrographs. We present the white dwarf cooling sequence using this filter. Our observations show that very cool white dwarfs form a sequence in the r-DDO vs. r-z color--color diagram and demonstrate that significant improvements are needed in white dwarf model atmospheres.Comment: Accepted for publication in A

Identification of Cool White Dwarfs in the NOAO Deep Wide-Field Survey

We report our search for the cool white dwarfs belonging to the Galactic disk by extending the NOAO Deep Wide-Field Survey. Narrow-band DDO51 photometry of the Deep Wide-Field Survey's northern field was obtained using the 4m-Mayall Telescope and the MOSAIC imager to separate cool white dwarfs from other stellar types of similar T_eff. Follow-up spectroscopy of four white dwarf candidates from our photometric search resulted in the discovery of two new cool white dwarfs as companions to M dwarfs.Comment: 2 pages, 2 figures, to appear in proceedings of the 13th European Workshop on White Dwarf

A new look at the pulsating DB white dwarf GD 358:Line-of-sight velocity measurements and constraints on model atmospheres

We report on our findings of the bright, pulsating, helium atmosphere white dwarf GD 358, based on time-resolved optical spectrophotometry. We identify 5 real pulsation modes and at least 6 combination modes at frequencies consistent with those found in previous observations. The measured Doppler shifts from our spectra show variations with amplitudes of up to 5.5 km/s at the frequencies inferred from the flux variations. We conclude that these are variations in the line-of-sight velocities associated with the pulsational motion. We use the observed flux and velocity amplitudes and phases to test theoretical predictions within the convective driving framework, and compare these with similar observations of the hydrogen atmosphere white dwarf pulsators (DAVs). The wavelength dependence of the fractional pulsation amplitudes (chromatic amplitudes) allows us to conclude that all five real modes share the same spherical degree, most likely, l=1. This is consistent with previous identifications based solely on photometry. We find that a high signal-to-noise mean spectrum on its own is not enough to determine the atmospheric parameters and that there are small but significant discrepancies between the observations and model atmospheres. The source of these remains to be identified. While we infer T_eff=24kK and log g~8.0 from the mean spectrum, the chromatic amplitudes, which are a measure of the derivative of the flux with respect to the temperature, unambiguously favour a higher effective temperature, 27kK, which is more in line with independent determinations from ultra-violet spectra.Comment: 14 pages, 11 figures; accepted for publication in A&

The Effect of Crystallization on the Pulsations of White Dwarf Stars

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the existence of a potentially crystallized DAV, BPM 37093, and the expectation that digital surveys in progress will yield many more such massive pulsators. A crystallized core makes possible a new class of oscillations, the torsional modes, although we expect these modes to couple at most weakly to any motions in the fluid and therefore to remain unobservable. The p-modes should be affected at the level of a few percent in period, but are unlikely to be present with observable amplitudes in crystallizing white dwarfs any more than they are in the other ZZ Ceti's. Most relevant to the observed light variations in white dwarfs are the g-modes. We find that the kinetic energy of these modes is effectively excluded from the crystallized cores of our models. As increasing crystallization pushes these modes farther out from the center, the mean period spacing between radial overtones increases substantially with the crystallized mass fraction. In addition, the degree and structure of mode trapping is affected. The fact that some periods are strongly affected by changes in the crystallized mass fraction while others are not suggests that we may be able to disentangle the effects of crystallization from those due to different surface layer masses.Comment: 18 pages, 5 figures, accepted on 1999 July 2 for publication in the Astrophysical Journa