26 research outputs found

    High-resolution Near-Infrared Images and Models of the Circumstellar Disk in HH 30

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    We present Hubble Space Telescope (HST) Near-Infrared Camera and Multi-object Spectrometer (NICMOS) observations of the reflection nebulosity associated with the T Tauri star HH 30. The images show the scattered light pattern characteristic of a highly inclined, optically thick disk with a prominent dustlane whose width decreases with increasing wavelength. The reflected nebulosity exhibits a lateral asymmetry in the upper lobe on the opposite side to that reported in previously published Wide Field Planetary Camera 2 (WFPC2) images. The radiation transfer model which most closely reproduces the data has a flared accretion disk with dust grains larger than standard interstellar medium grains by a factor of approximately 2.1. A single hotspot on the stellar surface provides the necessary asymmetry to fit the images and is consistent with previous modeling of the light curve and images. Photometric analysis results in an estimated extinction of Av>~80; however, since the photometry measures only scattered light rather than direct stellar flux, this a lower limit. The radiative transfer models require an extinction of Av = 7,900.Comment: Accepted for publication in Ap.

    JWST/NIRCam Imaging of Young Stellar Objects. II. Deep Constraints on Giant Planets and a Planet Candidate Outside of the Spiral Disk Around SAO 206462

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    We present JWST/NIRCam F187N, F200W, F405N and F410M direct imaging data of the disk surrounding SAO 206462. Previous images show a very structured disk, with a pair of spiral arms thought to be launched by one or more external perturbers. The spiral features are visible in three of the four filters, with the non-detection in F410M due to the large detector saturation radius. We detect with a signal-to-noise ratio of 4.4 a companion candidate (CC1) that, if on a coplanar circular orbit, would orbit SAO 206462 at a separation of ∌300\sim300 au, 2.25σ2.25\sigma away from the predicted separation for the driver of the eastern spiral. According to the BEX models, CC1 has a mass of MCC1=0.8±0.3 MJM_\mathrm{CC1}=0.8\pm0.3~M_\mathrm{J}. No other companion candidates were detected. At the location predicted by simulations of both spirals generated by a single massive companion, the NIRCam data exclude objects more massive than ∌2.2 MJ\sim2.2~M_\mathrm{J} assuming the BEX evolutionary models. In terms of temperatures, the data are sensitive to objects with Teff∌650−850T_{\text{eff}}\sim650-850 K, when assuming planets emit like blackbodies (RpR_\mathrm{p} between 1 and 3RJ3 R_\mathrm{J}). From these results, we conclude that if the spirals are driven by gas giants, these must be either cold or embedded in circumplanetary material. In addition, the NIRCam data provide tight constraints on ongoing accretion processes. In the low extinction scenario we are sensitive to mass accretion rates of the order M˙∌10−9MJ\dot{M}\sim10^{-9} M_\mathrm{J} yr−1^{-1}. Thanks to the longer wavelengths used to search for emission lines, we reach unprecedented sensitivities to processes with M˙∌10−7MJ\dot{M}\sim10^{-7} M_\mathrm{J} yr−1^{-1} even towards highly extincted environments (AV≈50A_\mathrm{V}\approx50~mag).Comment: 18 pages, 8 figures, 3 table

    JWST/NIRCam Imaging of Young Stellar Objects. I. Constraints on Planets Exterior to The Spiral Disk Around MWC 758

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    MWC 758 is a young star hosting a spiral protoplanetary disk. The spirals are likely companion-driven, and two previously-identified candidate companions have been identified -- one at the end the Southern spiral arm at ~0.6 arcsec, and one interior to the gap at ~0.1 arcsec. With JWST/NIRCam, we provide new images of the disk and constraints on planets exterior to ~1". We detect the two-armed spiral disk, a known background star, and a spatially resolved background galaxy, but no clear companions. The candidates that have been reported are at separations that are not probed by our data with sensitivity sufficient to detect them -- nevertheless, these observations place new limits on companions down to ~2 Jupiter-masses at ~150 au and ~0.5 Jupiter masses at ~600 au. Owing to the unprecedented sensitivity of JWST and youth of the target, these are among the deepest mass-detection limits yet obtained through direct imaging observations, and provide new insights into the system's dynamical nature.Comment: Accepted for publication in A

    The James Webb Space Telescope Mission

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    Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4m4m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5m6.5m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

    PremiÚre expérimentation de compensation par l'offre : bilan et perspective

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    MĂȘme s'il suscite encore de nombreux dĂ©bats, le principe de compensation Ă©cologique pour les dĂ©gĂątscausĂ©s Ă  la biodiversitĂ© lors de projets d’amĂ©nagements a finalement Ă©tĂ© adoptĂ© en mars dernierdans le cadre de la loi « BiodiversitĂ© ». À travers l'exemple de la rĂ©habilitation Ă©cologique et pastoraledu verger de Cossure en plaine de Crau, premiĂšre expĂ©rimentation française de compensationĂ©cologique par l'offre, les auteurs s'intĂ©ressent ici au bilan Ă©cologique et Ă©conomique de l'opĂ©rationpour en dĂ©gager les effets positifs, mais Ă©galement les dysfonctionnements et les limites

    Supplemental material - The Role of Dementia and Residential Service Agency Characteristics in the Care Experiences of Maryland Medicaid Home and Community-Based Service Participants and Family and Unpaid Caregivers

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    Supplemental material for The Role of Dementia and Residential Service Agency Characteristics in the Care Experiences of Maryland Medicaid Home and Community-Based Service Participants and Family and Unpaid Caregivers by Chanee Fabius, Roberto Millar, Erick Geil, Ian Stockwell, Christin Diehl, Deirdre Johnston, Joseph J. Gallo, and Jennifer L Wolff in Journal of Applied Gerontology</p

    THE ASTROPHYSICAL JOURNAL, 556 958969, 2001 August 1 V

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    We present Hubble Space Telescope near-infrared camera and multiobject spectrometer observations of the reection nebulosity associated with the T Tauri star HH 30. The images show the scattered-light pattern characteristic of a highly inclined, optically thick disk with a prominent dust lane whose width decreases with increasing wavelength. The reected nebulosity exhibits a lateral asymmetry in the upper lobe on the opposite side to that reported in previously published Wide Field Planetary Camera 2 images. The radiation transfer model that most closely reproduces the data has a ared accretion disk with dust grains larger than standard interstellar medium grains by a factor of approximately 2.1. A single hot spot on the stellar surface provides the necessary asymmetry to t the images and is consistent with previous modeling of the light curve and images. Photometric analysis results in an estimated extinction of however, since the photometry measures only scattered light rather than direct A Z 80 ; stellar ux, this a lower limit. The radiative transfer models require an extinction of A \ 7900

    JWST/NIRCam Imaging of Young Stellar Objects. III. Detailed Imaging of the Nebular Environment around the HL Tau Disk

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    As part of the James Webb Space Telescope (JWST) Guaranteed Time Observation program “Direct Imaging of YSOs” (program ID 1179), we use JWST NIRCam’s direct imaging mode in F187N, F200W, F405N, and F410M to perform high-contrast observations of the circumstellar structures surrounding the protostar HL Tau. The data reveal the known stellar envelope, outflow cavity, and streamers, but do not detect any companion candidates. We detect scattered light from an inflowing spiral streamer previously detected in HCO ^+ by the Atacama Large Millimeter/submillimeter Array, and part of the structure connected to the c-shaped outflow cavity. For detection limits in planet mass we use BEX evolutionary tracks when M _p < 2 M _J and AMES-COND evolutionary tracks otherwise, assuming a planet age of 1 Myr (youngest available age). Inside the disk region, due to extended envelope emission, our point-source sensitivities are ∌5 mJy (37 M _J ) at 40 au in F187N and ∌0.37 mJy (5.2 M _J ) at 140 au in F405N. Outside the disk region, the deepest limits we can reach are ∌0.01 mJy (0.75 M _J ) at a projected separation ∌ 525 au

    Compliance with antibiotic therapy guidelines in french paediatric intensive care units: a multicentre observational study

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    Abstract Background Bacterial infections (BIs) are widespread in ICUs. The aims of this study were to assess compliance with antibiotic recommendations and factors associated with non-compliance. Methods We conducted an observational study in eight French Paediatric and Neonatal ICUs with an antimicrobial stewardship programme (ASP) organised once a week for the most part. All children receiving antibiotics for a suspected or proven BI were evaluated. Newborns < 72 h old, neonates < 37 weeks, age ≄ 18 years and children under surgical antimicrobial prophylaxis were excluded. Results 139 suspected (or proven) BI episodes in 134 children were prospectively included during six separate time-periods over one year. The final diagnosis was 26.6% with no BI, 40.3% presumed (i.e., not documented) BI and 35.3% documented BI. Non-compliance with antibiotic recommendations occurred in 51.1%. The main reasons for non-compliance were inappropriate choice of antimicrobials (27.3%), duration of one or more antimicrobials (26.3%) and length of antibiotic therapy (18.0%). In multivariate analyses, the main independent risk factors for non-compliance were prescribing ≄ 2 antibiotics (OR 4.06, 95%CI 1.69–9.74, p = 0.0017), duration of broad-spectrum antibiotic therapy ≄ 4 days (OR 2.59, 95%CI 1.16–5.78, p = 0.0199), neurologic compromise at ICU admission (OR 3.41, 95%CI 1.04–11.20, p = 0.0431), suspected catheter-related bacteraemia (ORs 3.70 and 5.42, 95%CIs 1.32 to 15.07, p < 0.02), a BI site classified as “other” (ORs 3.29 and 15.88, 95%CIs 1.16 to 104.76, p < 0.03), sepsis with ≄ 2 organ dysfunctions (OR 4.21, 95%CI 1.42–12.55, p = 0.0098), late-onset ventilator-associated pneumonia (OR 6.30, 95%CI 1.15–34.44, p = 0.0338) and ≄ 1 risk factor for extended-spectrum ÎČ-lactamase-producing Enterobacteriaceae (OR 2.56, 95%CI 1.07–6.14, p = 0.0353). Main independent factors for compliance were using antibiotic therapy protocols (OR 0.42, 95%CI 0.19–0.92, p = 0.0313), respiratory failure at ICU admission (OR 0.36, 95%CI 0.14–0.90, p = 0.0281) and aspiration pneumonia (OR 0.37, 95%CI 0.14–0.99, p = 0.0486). Conclusions Half of antibiotic prescriptions remain non-compliant with guidelines. Intensivists should reassess on a day-to-day basis the benefit of using several antimicrobials or any broad-spectrum antibiotics and stop antibiotics that are no longer indicated. Developing consensus about treating specific illnesses and using department protocols seem necessary to reduce non-compliance. A daily ASP could also improve compliance in these situations. Trial Registration ClinicalTrials.gov: number NCT04642560. The date of first trial registration was 24/11/2020

    JWST/NIRCam Imaging of Young Stellar Objects. II. Deep Constraints on Giant Planets and a Planet Candidate Outside of the Spiral Disk Around SAO 206462

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    We present JWST/NIRCam F187N, F200W, F405N, and F410M direct imaging data of the disk surrounding SAO 206462. Previous images show a very structured disk, with a pair of spiral arms thought to be launched by one or more external perturbers. The spiral features are visible in three of the four filters, with the nondetection in F410M due to the large detector saturation radius. We detect with a signal-to-noise ratio of 4.4 a companion candidate that, if on a coplanar circular orbit, would orbit SAO 206462 at a separation of ∌300 au, 2.25 σ away from the predicted separation for the driver of the eastern spiral. No other companion candidates were detected. At the location predicted by simulations of both spirals generated by a single massive companion, the NIRCam data exclude objects more massive than ∌2.2 M _J assuming the BEX evolutionary models. In terms of temperatures, the data are sensitive to objects with T _eff ∌ 650–850 K, when assuming planets emit like blackbodies ( R _p between 1 and 3 R _J ). From these results, we conclude that if the spirals are driven by gas giants, these must be either cold or embedded in circumplanetary material. In addition, the NIRCam data provide tight constraints on ongoing accretion processes. In the low extinction scenario we are sensitive to mass accretion rates of the order M˙∌10−9MJ\dot{M}\sim {10}^{-9}{M}_{{\rm{J}}} yr ^−1 . Thanks to the longer wavelengths used to search for emission lines, we reach unprecedented sensitivities to processes with M˙∌10−7MJ\dot{M}\sim {10}^{-7}{M}_{{\rm{J}}} yr ^−1 even toward highly extincted environments ( A _V ≈ 50 mag)
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