V1647 Orionis: One Year into Quiescence Aspin, Colin; Beck, Tracy L; Reipurth, Bo
The Astronomical journal,
01/2008, Letnik:
135, Številka:
1
Journal Article
We present 2.0-2.4 mum integral field spectroscopy at adaptive optics spatial resolution ( similar to 0.1 super(image )) obtained with the Near-infrared Integral Field Spectrograph (NIFS) at Gemini ...North Observatory of six classical T Tauri stars: T Tau, DG Tau, XZ Tau, HL Tau, RW Aur, and HV Tau C. In all cases, the image S(1) (2.12 mum) emission is detected at spatially extended distances from the central stars. Moreover, HL Tau, T Tau, RW Aur, and HV Tau C have H sub(2) that extends to projected distances of more than similar to 200 AU from the stars. Integrated over the IFU field, most of the H sub(2) emission is not spatially coincident with the location of continuum flux. Multiple H sub(2) transitions detected in the K-band spectra show that level populations are typical of gas in thermal equilibrium with excitation temperatures in the 1800-2300 K range. Three of the stars have H sub(2) velocity profiles that are centered approximately at the stellar radial velocity, and three show velocity shifts with respect to the system. Each of the stars studied here exhibit H sub(2) morphologies, spatial extents, excitation temperatures, and kinematics that are most consistent with shock- excited emission from the inner regions of the known Herbig-Haro energy flows or from spatially extended wide-angle winds encompassing the outflows rather than predominantly from H sub(2) stimulated quiescently by UV or X-ray emission from the central stars. The data presented in this study highlights the sensitivity of adaptive-optics-fed integral field spectroscopy for spatially resolving emission line structures in the environments of bright young stars.
To investigate the association between sleep disordered breathing (SDB) and severe chronic periodontitis.
Cross-sectional data analysis from the Hispanic Community Health Study/Study of Latinos.
...Community-based setting with probability sampling from four urban US communities.
12,469 adults aged 18-74 y.
None.
Severe chronic periodontitis was defined using the Centers for Disease Control and Prevention/American Academy of Periodontology case classification based on full-mouth periodontal assessments performed by calibrated dentists. SDB was evaluated in standardized home sleep tests, and defined as the number of apnea plus hypopnea events associated with ≥ 3% desaturation, per hour of estimated sleep. SDB was quantified using categories of the apnea-hypopnea index (AHI): 0.0 events (nonapneic); 0.1-4.9 (subclinical); 5.0-14.9 (mild); and ≥ 15 (moderate/severe). Covariates were demographic characteristics and established periodontitis risk factors. C-reactive protein was a potential explanatory variable. Using survey estimation, multivariable binary logistic regression estimated odds ratios (OR) and 95% confidence limits (CL). Following adjustment for confounding, the SDB and periodontitis relationship remained statistically significant, but was attenuated in strength and no longer dose-response. Compared with the nonapneic referent, adjusted odds of severe periodontitis were 40% higher with subclinical SDB (OR = 1.4, 95% CL: 1.0, 1.9), 60% higher with mild SDB (OR = 1.6, 95% CL: 1.1, 2.2) and 50% higher with moderate/severe SDB (OR = 1.5, 95% CL: 1.0, 2.3) demonstrating an independent association between SDB and severe periodontitis.
This study identifies a novel association between mild sleep disordered breathing and periodontitis that was most pronounced in young adults.
Stress is a common trigger in affective disorder onset, yet the mechanism and predisposing factors of vulnerability remain unknown. Effective disease prevention requires a critical balance of ...responses within the serotonergic raphe nucleus, including a coordination of corticotropin-releasing factor (CRF) actions at both of its receptors, CRF receptor-1 and CRF receptor-2. Mice deficient in CRF receptor-2 (R2KO) were used as a model of maladaptive stress responsivity to examine the physiological and molecular markers of stress dysregulation within the raphe in the absence of this receptor. After chronic stress, R2KO mice failed to display the robust stress-mediated adaptations characteristic of control mice, including elevations in tryptophan hydroxylase-2 and CRF receptor-1 expression and concordant increases in behavioral arousal. As a further indication of failed homeostatic mechanisms, R2KO mice displayed indices of cell death in the raphe after stress exposure, with elevations in proapoptotic factors but a failure to mount adaptive increases in antiapoptotic factors found in control mice. In vitro electrophysiological characterization of the specific influence of CRF on the raphe revealed both basal differences and a failure to respond to CRF administration in R2KO mice. These results support a requirement for homeostatic maintenance in response to stress in the raphe, where dysregulation may be a critical predictor of affective disorder onset.
We present high spatial resolution maps of ro-vibrational molecular hydrogen emission from the environment of the GG Tau A binary component in the GG Tau quadruple system. The H sub(2) upsilon = 1-0 ...S(1) emission is spatially resolved and encompasses the inner binary, with emission detected at locations that should be dynamically cleared on several hundred year timescales. Extensions of H sub(2) gas emission are seen to ~100 AU distances from the central stars. The upsilon = 2-1 S(1) emission at 2.24 mu m is also detected at ~30 AU from the central stars, with a line ratio of 0.05 + or - 0.01 with respect to the upsilon = 1-0 S(1) emission. Assuming gas in LTE, this ratio corresponds to an emission environment at ~1700 K. We estimate that this temperature is too high for quiescent gas heated by X-ray or UV emission from the central stars. Surprisingly, we find that the brightest region of H sub(2) emission arises from a spatial location that is exactly coincident with a recently revealed dust "streamer" which seems to be transferring material from the outer circumbinary ring around GG Tau A into the inner region. As a result, we identify a new excitation mechanism for ro-vibrational H sub(2) stimulation in the environment of young stars. The H sub(2) in the GG Tau A system appears to be stimulated by mass accretion infall as material in the circumbinary ring accretes onto the system to replenish the inner circumstellar disks. We postulate that H sub(2) stimulated by accretion infall could be present in other systems, particularly binaries and "transition disk" systems which have dust-cleared gaps in their circumstellar environments.
Abstract Purpose The aim of the study was to examine acculturation and established risk factors in explaining variation in periodontitis prevalence among Hispanic/Latino subgroups. Methods ...Participants were 12,730 dentate adults aged 18–74 years recruited into the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) from four U.S. field centers between 2008 and 2011. A standardized periodontal assessment measured probing pocket depth and gingival recession at six sites per tooth for up to 28 teeth. Periodontitis was defined according to the Centers for Disease Control and Prevention and American Academy of Periodontology case classifications developed for population surveillance. Covariates included acculturation indicators and established periodontitis risk factors. Survey estimation procedures took account of the complex sampling design. Adjusted multivariate binomial regression estimated prevalence ratios and 95% confidence limits (CLs). Results Unadjusted prevalence of moderate and severe periodontitis was 38.5% and ranged from 24.7% among Dominicans to 52.1% among Cubans. Adjusted prevalence ratios for subgroups relative to Dominicans were as follows: (1) 1.34 (95% CL, 1.13–1.58) among South Americans; (2) 1.37 (95% CL, 1.17–1.61) among Puerto Ricans; (3) 1.43 (95% CL, 1.25–1.64) among Mexicans; (4) 1.53 (95% CL, 1.32–1.76) among Cubans; and (5) 1.55 (95% CL, 1.35–1.78) among Central Americans. Conclusions Heterogeneity in prevalence of moderate/severe periodontitis among Hispanic/Latino subpopulations was not explained by acculturation or periodontitis risk factors.
We present high-resolution 1.06.1.28 mum spectra toward the interacting binary UY Aur obtained with GEMINI/NIFS and the adaptive optics system Altair. We have detected FeII lambda 1.257mum and He ...lambda1.083mum lines from both UY Aur A (the primary source) and UY Aur B (the secondary). In FeII UY Aur A drives fast and widely opening outflows with an opening angle of ~90degrees. along a position angle of ~40degrees, while UY Aur B is associated with a redshifted knot. The blueshifted and redshifted emissions show a complicated structure between the primary and secondary. The radial velocities of the FeII emission features are similar for UY Aur A and B: ~-.100 km s super(-1) for the blueshifted emission and ~ super(+)130 km s super(-1) for the redshifted component. The He I line profile observed toward UY Aur A comprises a central emission feature with deep absorptions at both blueshifted and redshifted velocities. These absorption features may be explained by stellar wind models. The He I line profile of UY Aur B shows only an emission feature.
High-accuracy mass measurements of neutron-deficient Yb isotopes have been performed at TRIUMF using TITAN's multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). For the first time, an ...MR-TOF-MS was used on line simultaneously as an isobar separator and as a mass spectrometer, extending the measurements to two isotopes further away from stability than otherwise possible. The ground state masses of 150,153Yb and the excitation energy of 151Ybm were measured for the first time. As a result, the persistence of the N = 82 shell with almost unmodified shell gap energies is established up to the proton drip line. Furthermore, the puzzling systematics of the h11/2-excited isomeric states of the N = 81 isotones are unraveled using state-of-the-art mean field calculations.
A photometric and spectral study of the variable star V2494 Cyg in the L 1003 dark cloud is presented. The brightness of the star, formerly known as HH 381 IRS, increased by 2.5 mag in R (probably in ...the 1980s) and since then has remained nearly constant. Since the brightness increase, V2494 Cyg has illuminated a bipolar cometary nebula. The stellar spectrum has several features typical of the FU Ori (FUor) type, plus it exhibits very strong Hα and forbidden emission lines with high-velocity components. These emission lines originate in the Herbig-Haro (HH) jet near the star. The kinematic age of the jet is consistent with it forming at the time of the outburst leading to the luminosity increase. V2494 Cyg also produces a rather extended outflow; it is the first known FUor with both an observed outburst and a parsec-sized HH flow. The nebula, illuminated by V2494 Cyg, possesses similar morphological and spectral characteristics to Hubble's variable nebula (R Monocerotis/NGC 2261).
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