Context.
The conventional approach to direct imaging is to use a single aperture coronagraph with wavefront correction via extreme adaptive optics (AO). Such systems are limited to observing beyond ...an inner working angle (IWA) of a few
λ
/
D.
Nulling interferometry with two or more apertures will enable detections of companions at separations at and beyond the formal diffraction limit.
Aims.
In this paper, we evaluate the astrophysical potential of a kernel-nuller as the prime high-contrast imaging mode of the Very Large Telescope Interferometer (VLTI).
Methods.
By taking into account baseline projection effects induced by Earth rotation, we introduce some diversity in the response of the nuller as a function of time. This response is depicted by transmission maps. We also determine whether we can extract the astrometric parameters of a companion from the kernel outputs, which are the primary intended observable quantities of the kernel-nuller. This then leads us to comment on the characteristics of a possible observing program for the discovery of exoplanets.
Results.
We present transmission maps for both the raw nuller outputs and their subsequent kernel outputs. To further examine the properties of the kernel-nuller, we introduce maps of the absolute value of the kernel output. We also identify 38 targets for the direct detection of exoplanets with a kernel-nuller at the focus of the VLTI.
Conclusions.
With continued upgrades of the VLTI infrastructure, which will reduce fringe tracking residuals, a kernel-nuller would enable the detection of young giant exoplanets at separations <10 AU, where radial velocity and transit methods are more sensitive.
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Objective
This study aimed to compare stress, burnout, stressors, and protective factors among regional‐ and metropolitan‐based Australian medical doctors.
Method
A mixed methods design was utilized ...with 252 Australian medical doctors completing an online questionnaire package. A subsample also completed qualitative interviews.
Results
Stress was significantly higher among doctors compared with population norms. Over half of doctors reported burnout on one or more dimensions. The strongest unique predictors were being female, working late, and work–family conflict. Qualitatively, 12 stressors (e.g., training and competition, workload, and time management) and 9 protective subthemes (e.g., being well resourced, clinical interest) emerged across system‐level, clinical environment‐level, and individual factor and personal response themes.
Conclusions
Stress and burnout among doctors are alarmingly high and both system/organization‐level (e.g., communication systems, workload, flexible work arrangements) and individual‐level (e.g., fostering resilience/coping strategies) predictors are implicated by our results. These may be useful targets for future interventions.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Photonic technologies will be at the heart of future terrestrial planet hunting interferometers. In particular the mid-infrared spectral region between 3.5 - 4.2 μm is the ideal window for hunting ...for young extra-solar planets, since the planet is still hot from its formation and thus offers a favorable contrast with respect to the parent star compared to other spectral regions. This paper demonstrates two basic photonic building blocks of such an instrument, namely single-mode waveguides with propagation losses as low as 0.29±0.03 dB/cm at a wavelength of 4 μm as well as directional couplers with a constant splitting ratio across a broad wavelength band of 500 nm. The devices are based on depressed cladding waveguides inscribed into ZBLAN glass using the femtosecond laser direct-write technique. This demonstration is the first stepping stone towards the realization of a high transmission mid-infrared nulling interferometer.
Emotion regulation (ER) theories and measurement scales have received considerable attention in clinical and research settings. However, there is a need for independent validation of these scales to ...ensure rigor within this field. The aim of the current study was to examine the factorial, convergent, and criterion validity of one of the most popular measures of ER, the Cognitive Emotion Regulations Questionnaire (CERQ), both short and long form.
The CERQ (and CERQ-short), positive and negative affect schedule, and difficulties in emotion regulation scale were administered to 795 participants (70% female, M age=36.36).
Confirmatory factor analysis supported the 9-factor structure of the CERQ-short, but not the full CERQ. Adequate fit for the full CERQ was achieved after the removal of three poorly performing items. Correlations supported the convergent and criterion validity of both scales, although the CERQ-short demonstrated weaker associations than the full scale.
The factorial, convergent, and criterion validity of the CERQ and CERQ-short were generally supported. However, future research may wish to examine several high inter-factor correlations that were observed among the full CERQ, as well as the weaker validity demonstrated by the CERQ-short.
•The factorial, convergent, and criterion validity of the CERQ and CERQ-short were examined.•The 9-factor structure was supported for the CERQ-short, and for a modified CERQ.•Convergent and criterion validity was supported, but appear to be weaker for the CERQ-short.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Changes in penguin populations on the Antarctic Peninsula have been linked to several environmental factors, but the potentially devastating impact of volcanic activity has not been considered. Here ...we use detailed biogeochemical analyses to track past penguin colony change over the last 8,500 years on Ardley Island, home to one of the Antarctic Peninsula's largest breeding populations of gentoo penguins. The first sustained penguin colony was established on Ardley Island c. 6,700 years ago, pre-dating sub-fossil evidence of Peninsula-wide occupation by c. 1,000 years. The colony experienced five population maxima during the Holocene. Overall, we find no consistent relationships with local-regional atmospheric and ocean temperatures or sea-ice conditions, although the colony population maximum, c. 4,000-3,000 years ago, corresponds with regionally elevated temperatures. Instead, at least three of the five phases of penguin colony expansion were abruptly ended by large eruptions from the Deception Island volcano, resulting in near-complete local extinction of the colony, with, on average, 400-800 years required for sustainable recovery.
ABSTRACT
We present the results of a medium-resolution optical spectroscopic survey of 92 cool ($3000 \,\mathrm{ K}\lesssim T_{\rm eff} \lesssim 4500\,$K) southern TESS candidate planet hosts, and ...describe our spectral fitting methodology used to recover stellar parameters. We quantify model deficiencies at predicting optical fluxes, and while our technique works well for Teff, further improvements are needed for Fe/H. To this end, we developed an updated photometric Fe/H calibration for isolated main-sequence stars built upon a calibration sample of 69 cool dwarfs in binary systems, precise to $\pm 0.19\,$dex, from supersolar to metal poor, over 1.51 < Gaia (BP − RP) < 3.3. Our fitted Teff and R⋆ have median precisions of 0.8 per cent and 1.7 per cent, respectively, and are consistent with our sample of standard stars. We use these to model the transit light curves and determine exoplanet radii for 100 candidate planets to 3.5 per cent precision and see evidence that the planet radius gap is also present for cool dwarfs. Our results are consistent with the sample of confirmed TESS planets, with this survey representing one of the largest uniform analyses of cool TESS candidate planet hosts to date.
We present velocity-resolved spectroastrometric imaging of the 4.7 mum rovibrational lines of CO gas in protoplanetary disks using the CRIRES high- resolution infrared spectrometer on the Very Large ...Telescope (VLT). The method as applied to three disks with known dust gaps or inner holes out to 4-45 AU (SR 21, HD 135344B, and TW Hya) achieves an unprecedented spatial resolution of 0.1-0.5 AU. While one possible gap formation mechanism is dynamical clearing by giant planets, other equally good explanations (stellar companions, grain growth, photoevaporation) exist. One way of distinguishing between different scenarios is the presence and distribution of gas inside the dust gaps. Keplerian disk models are fit to the spectroastrometric position-velocity curves to derive geometrical parameters of the molecular gas. We determine the position angles and inclinations of the inner disks with accuracies as good as 1 degree -2 degree , as well as the radial extent of the gas emission. Molecular gas is detected well inside the dust gaps in all three disks. The gas emission extends to within a radius of 0.5 AU for HD 135344B and to 0.1 AU for TW Hya, supporting partial clearing by a <1-10 M sub(Jup) planetary body as the cause of the observed dust gaps, or removal of the dust by extensive grain coagulation and planetesimal formation. The molecular gas emission in SR 21 appears to be truncated within image7 AU, which may be caused by complete dynamical clearing by a more massive companion. We find a smaller inclination angle of the inner disk of TW Hya than that determined for the outer disk, suggestive of a disk warp. We also detect significant azimuthal asymmetries in the SR 21 and HD 135344B inner disks.
Dynamics of small grains in transitional discs Krumholz, Mark R; Ireland, Michael J; Kratter, Kaitlin M
Monthly notices of the Royal Astronomical Society,
10/2020, Volume:
498, Issue:
2
Journal Article
Peer reviewed
Open access
ABSTRACT
Transitional discs have central regions characterized by significant depletion of both dust and gas compared to younger, optically thick discs. However, gas and dust are not depleted by ...equal amounts: gas surface densities are typically reduced by factors of ∼100, but small dust grains are sometimes depleted by far larger factors, to the point of being undetectable. While this extreme dust depletion is often attributed to planet formation, in this paper we show that another physical mechanism is possible: expulsion of grains from the disc by radiation pressure. We explore this mechanism using 2D simulations of dust dynamics, simultaneously solving the equation of radiative transfer with the evolution equations for dust diffusion and advection under the combined effects of stellar radiation and hydrodynamic interaction with a turbulent, accreting background gas disc. We show that, in transition discs that are depleted in both gas and dust fraction by factors of ∼100–1000 compared to minimum mass Solar nebular values, and where the ratio of accretion rate to stellar luminosity is low ($\dot{M}/L \lesssim 10^{-10}\, \mathrm{ M}_\odot$ yr$^{-1}\, \mathrm{ L}_\odot ^{-1}$), radiative clearing of any remaining ${\sim}0.5\, \mu\mathrm{ m}$ and larger grains is both rapid and inevitable. The process is size-dependent, with smaller grains removed fastest and larger ones persisting for longer times. Our proposed mechanism thus naturally explains the extreme depletion of small grains commonly found in transition discs. We further suggest that the dependence of this mechanism on grain size and optical properties may explain some of the unusual grain properties recently discovered in a number of transition discs. The simulation code we develop is freely available.
The present study aimed to provide the first psychometric evaluation of the newly developed, digitally animated assessment instrument: the Interactive Child Distress Screener (ICDS). The latent ...factor structure of the novel ICDS was first established using exploratory factor analysis (EFA) on 15 pairs of animated items using a community sample (N = 266) of child–parent dyads. EFA results support a two-factor structure representing two broad domains of internalizing and externalizing difficulties (r = .52) and comprised 12 items. The reliability of the factors was strong with ordinal alpha and omega coefficients above .84 and .87, respectively, for each of the subscales. Convergent validity for the overall sample was supported with established child and parent-reported measures of internalizing and externalizing problems; however, the ICDS factors demonstrated convergence greater in magnitude with other child-reported measures such as the Me and My School Survey. Satisfaction and utility ratings by children indicated that the digital format was highly acceptable.
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