Mira variables: An informal review

The structure of the Mira variables is discussed with particular emphasis on the extent of their observable atmospheres, the various methods for measuring the sizes of these atmospheres, and the manner in which the size changes through the cycle. The results obtained by direct, photometric and spectroscopic methods are compared, and the problems of interpretation are addressed. Also, a simple model for the atmospheric structure and motions of Miras based on recent observations of the doubling of infrared molecualr times is described. This model, consisting of two atmospheric layers plus a circumstellar shell, provides a physically plausible picture of the atmosphere which is consistent with the photometrically measured magnitude and temperature variations as well as the spectroscopic data

Notes on the early-type components of W Cep, o Cet, CH Cyg, AR Mon, and BL Tel

Low resolution IUE spectra in both spectral regions are used to clarify the nature of the warmer components of several binary systems. The W Cep, the primary of which is a luminous K-type supergiant, shows an ultraviolet absorption spectrum of type B0 or B1; this system is heavily reddened. The hot companion of Mira (o Cet) is surprisingly faint in the short wavelength region, but it excites a rich emission spectrum from the surrounding gas. The ultraviolet active M7 giant CH Cyg is shown to be a binary with a hot companion. This system was also observed at high resolution and shows variable Fe II emission and well-separated circumstellar and interstellar absorptions within the broad Mg II emission profiles. The eclipsing binaries AR Mon and BL Tel are shown not to have hot companions

Detection of H_2 Pure Rotational Line Emission from the GG Tauri Binary System

We present the first detection of the low-lying pure rotational emission lines of H_2 from circumstellar disks around T Tauri stars, using the Short Wavelength Spectrometer on the Infrared Space Observatory. These lines provide a direct measure of the total amount of warm molecular gas in disks. The J = 2 → 0 S(0) line at 28.218 μm and the J = 3 → 1 S(1) line at 17.035 μm have been observed toward the double binary system GG Tau. Together with limits on the J = 5 → 3 S(3) and J = 7 → 5 S(5) lines, the data suggest the presence of gas at T_(kin) ≈ 110 ± 10 K with a mass of (3.6 ± 2.0) × 10^(-3) M_☉ (±3 σ). This amounts to ~3% of the total gas + dust mass of the circumbinary disk as imaged by millimeter interferometry, but it is larger than the estimated mass of the circumstellar disk(s). Possible origins for the warm gas seen in H_2 are discussed in terms of photon and wind-shock heating mechanisms of the circumbinary material, and comparisons with model calculations are made

Semiclassical theory of the effects of collisions between rotors on molecular spectral lineshapes. II. Calculations for several systems

The T2 (microwave line broadening) and T1 (microwave transient experiments) collisional cross sections are obtained by Monte Carlo trajectory evaluations of semiclassical (WKB) expressions for those quantities derived in a previous paper in this series. The calculated values of the cross sections presented here yields the relation T1~T2 (within standard error) for the systems OCS–OCS, OCS–N2, OCS–H2, OCS–CO2, and HCN–HCN, a result which agrees with recent experimental findings. Reasonable agreement was also found between the calculated values of the T2 cross section and those observed spectroscopically

Quantitative atomic spectroscopy for primary thermometry

Quantitative spectroscopy has been used to measure accurately the Doppler-broadening of atomic transitions in $^{85}$Rb vapor. By using a conventional platinum resistance thermometer and the Doppler thermometry technique, we were able to determine $k_B$ with a relative uncertainty of $4.1\times 10^{-4}$, and with a deviation of $2.7\times 10^{-4}$ from the expected value. Our experiment, using an effusive vapour, departs significantly from other Doppler-broadened thermometry (DBT) techniques, which rely on weakly absorbing molecules in a diffusive regime. In these circumstances, very different systematic effects such as magnetic sensitivity and optical pumping are dominant. Using the model developed recently by Stace and Luiten, we estimate the perturbation due to optical pumping of the measured $k_B$ value was less than $4\times 10^{-6}$. The effects of optical pumping on atomic and molecular DBT experiments is mapped over a wide range of beam size and saturation intensity, indicating possible avenues for improvement. We also compare the line-broadening mechanisms, windows of operation and detection limits of some recent DBT experiments

Line Intensities and Molecular Opacities of the FeH F4Δi−X4ΔiF^4\Delta_i-X^4\Delta_i Transition

We calculate new line lists and opacities for the $F^4\Delta_i-X^4\Delta_i$ transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new Einstein A values for each line are based on a high level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (H\"onl-London factors) are derived for both the Hund's case (a) and (b) coupling limits. A new set of spectroscopic constants were derived from the existing FeH term values for v=0, 1 and 2 levels of the $X$ and $F$ states. Using these constants extrapolated term values were generated for v=3 and 4 and for $J$ values up to 50.5. The line lists (including Einstein A values) for the 25 vibrational bands with v$\leq$4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were use to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507.Comment: 52 pages, 3 figures, many tables, accepted for publication in the Astrophysical Journal Supplement

Domain-general subregions of the medial prefrontal cortex contribute to recovery of language after stroke

We hypothesized that the recovery of speech production after left hemisphere stroke not only depends on the integrity of language-specialized brain systems, but also on ‘domain-general’ brain systems that have much broader functional roles. The presupplementary motor area/dorsal anterior cingulate forms part of the cingular-opercular network, which has a broad role in cognition and learning. Consequently, we have previously suggested that variability in the recovery of speech production after aphasic stroke may relate in part to differences in patients’ abilities to engage this domain-general brain region. To test our hypothesis, 27 patients (aged 59 ± 11 years) with a left hemisphere stroke performed behavioural assessments and event-related functional magnetic resonance imaging tasks at two time points; first in the early phase (∼2 weeks) and then ∼4 months after the ictus. The functional magnetic resonance imaging tasks were designed to differentiate between activation related to language production (sentential overt speech production—Speech task) and activation related to cognitive processing (non-verbal decision making). Simple rest and counting conditions were also included in the design. Task-evoked regional brain activations during the early and late phases were compared with a longitudinal measure of recovery of language production. In accordance with a role in cognitive processing, substantial activity was observed within the presupplementary motor area/dorsal anterior cingulate during the decision-making task. Critically, the level of activation within this region during speech production correlated positively with the longitudinal recovery of speech production across the two time points (as measured by the in-scanner performance in the Speech task). This relationship was observed for activation in both the early phase (r = 0.363, P = 0.03 one-tailed) and the late phase (r = 0.538, P = 0.004). Furthermore, presupplementary motor area/dorsal anterior cingulate activity was a predictor of both language recovery over time and language outcome at ∼4 months, over and above that predicted by lesion volume, age and the initial language impairment (general linear model overall significant at P < 0.0001; ExpB 1.01, P = 0.02). The particularly prominent relationship of the presupplementary motor area/dorsal anterior cingulate region with recovery of language was confirmed in voxel-wise correlation analysis, conducted unconstrained for the whole brain volume. These results accord with the hypothesis that the functionality of the presupplementary motor area/dorsal anterior cingulate contributes to language recovery after stroke. Given that this brain region is often spared in aphasic stroke, we propose that it is a sensible target for future research into rehabilitative treatments. More broadly, baseline assessment of domain-general systems could help provide a better prediction of language recovery

Transistor Circuits

Contains reports on three research projects

Deconstructing Weight Management Interventions for Young Adults: Looking Inside the Black Box of the EARLY Consortium Trials.

ObjectiveThe goal of the present study was to deconstruct the 17 treatment arms used in the Early Adult Reduction of weight through LifestYle (EARLY) weight management trials.MethodsIntervention materials were coded to reflect behavioral domains and behavior change techniques (BCTs) within those domains planned for each treatment arm. The analytical hierarchy process was employed to determine an emphasis profile of domains in each intervention.ResultsThe intervention arms used BCTs from all of the 16 domains, with an average of 29.3 BCTs per intervention arm. All 12 of the interventions included BCTs from the six domains of Goals and Planning, Feedback and Monitoring, Social Support, Shaping Knowledge, Natural Consequences, and Comparison of Outcomes; 11 of the 12 interventions shared 15 BCTs in common across those six domains.ConclusionsWeight management interventions are complex. The shared set of BCTs used in the EARLY trials may represent a core intervention that could be studied to determine the required emphases of BCTs and whether additional BCTs add to or detract from efficacy. Deconstructing interventions will aid in reproducibility and understanding of active ingredients

Detection of H2 pure rotational line emission from the GG~Tau binary system

We present the first detection of the low-lying pure rotational emission lines of H2 from circumstellar disks around T~Tauri stars, using the Short Wavelength Spectrometer on the Infrared Space Observatory. These lines provide a direct measure of the total amount of warm molecular gas in disks. The J=2->0 S(0) line at 28.218 mum and the J=3->1 S(1) line at 17.035 mum have been observed toward the double binary system GG Tau. Together with limits on the J=5->3 S(3) and J=7->5 S(5) lines, the data suggest the presence of gas at T_kin=110+-10 K with a mass of (3.6+-2.0)x10^-3 M_sol (3sigma). This amounts to ~3% of the total gas + dust mass of the circumbinary disk as imaged by millimeter interferometry, but is larger than the estimated mass of the circumstellar disk(s). Possible origins for the warm gas seen in H2 are discussed in terms of photon and wind-shock heating mechanisms of the circumbinary material, and comparisons with model calculations are made.Comment: 14 pages including 1 figure. To appear in Astrophysical Journal Letter