110 research outputs found
Duration of Posttraumatic Amnesia Predicts Neuropsychological and Global Outcome in Complicated Mild Traumatic Brain Injury.
OBJECTIVES: Examine the effects of posttraumatic amnesia (PTA) duration on neuropsychological and global recovery from 1 to 6 months after complicated mild traumatic brain injury (cmTBI).
PARTICIPANTS: A total of 330 persons with cmTBI defined as Glasgow Coma Scale score of 13 to 15 in emergency department, with well-defined abnormalities on neuroimaging.
METHODS: Enrollment within 24 hours of injury with follow-up at 1, 3, and 6 months.
MEASURES: Glasgow Outcome Scale-Extended, California Verbal Learning Test II, and Controlled Oral Word Association Test. Duration of PTA was retrospectively measured with structured interview at 30 days postinjury.
RESULTS: Despite all having a Glasgow Coma Scale Score of 13 to 15, a quarter of the sample had a PTA duration of greater than 7 days; half had PTA duration of 1 of 7 days. Both cognitive performance and Extended Glasgow Outcome Scale outcomes were strongly associated with time since injury and PTA duration, with those with PTA duration of greater than 1 week showing residual moderate disability at 6-month assessment.
CONCLUSIONS: Findings reinforce importance of careful measurement of duration of PTA to refine outcome prediction and allocation of resources to those with cmTBI. Future research would benefit from standardization in computed tomographic criteria and use of severity indices beyond Glasgow Coma Scale to characterize cmTBI
TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Data from the newly-commissioned \textit{Transiting Exoplanet Survey
Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf
located 15 pc away. The planet has a radius of and
orbits the star every 11 hours. Although the existence of an atmosphere around
such a strongly irradiated planet is questionable, the star is bright enough
(, ) for this possibility to be investigated with transit and
occultation spectroscopy. The star's brightness and the planet's short period
will also facilitate the measurement of the planet's mass through Doppler
spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use
of the TESS Alert data, which is currently in a beta test phase, using data
from the pipelines at the TESS Science Office and at the TESS Science
Processing Operations Cente
TESS Discovery of a Transiting Super-Earth in the Mensae System
We report the detection of a transiting planet around Mensae (HD
39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The
solar-type host star is unusually bright (V=5.7) and was already known to host
a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered
planet has a size of and an orbital period of 6.27
days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays
a 6.27-day periodicity, confirming the existence of the planet and leading to a
mass determination of . The star's proximity and
brightness will facilitate further investigations, such as atmospheric
spectroscopy, asteroseismology, the Rossiter--McLaughlin effect, astrometry,
and direct imaging.Comment: Accepted for publication ApJ Letters. This letter makes use of the
TESS Alert data, which is currently in a beta test phase. The discovery light
curve is included in a table inside the arxiv submissio
Exploring the atmospheric dynamics of the extreme ultra-hot Jupiter KELT-9b using TESS photometry
We carry out a phase-curve analysis of the KELT-9 system using photometric
observations from NASA's Transiting Exoplanet Survey Satellite (TESS). The
measured secondary eclipse depth and peak-to-peak atmospheric brightness
modulation are ppm and ppm, respectively. The
planet's brightness variation reaches maximum minutes before the
midpoint of the secondary eclipse, indicating a
eastward shift in the dayside hot
spot from the substellar point. We also detect stellar pulsations on KELT-9
with a period of hours. The dayside emission of KELT-9b in
the TESS bandpass is consistent with a blackbody brightness temperature of
K. The corresponding nightside brightness temperature is
K, comparable to the dayside temperatures of the hottest known
exoplanets. In addition, we detect a significant phase-curve signal at the
first harmonic of the orbital frequency and a marginal signal at the second
harmonic. While the amplitude of the first harmonic component is consistent
with the predicted ellipsoidal distortion modulation assuming equilibrium
tides, the phase of this photometric variation is shifted relative to the
expectation. Placing KELT-9b in the context of other exoplanets with
phase-curve observations, we find that the elevated nightside temperature and
relatively low day-night temperature contrast agree with the predictions of
atmospheric models that include H dissociation and recombination. The
nightside temperature of KELT-9b implies an atmospheric composition containing
about 50% molecular and 50% atomic hydrogen at 0.1 bar, a nightside emission
spectrum that deviates significantly from a blackbody, and a 0.5-2.0 m
transmission spectrum that is featureless at low resolution.Comment: Published in AJ, updated with proof corrections. 17 pages, 8 figure
Exploring the Atmospheric Dynamics of the Extreme Ultrahot Jupiter KELT-9b Using TESS Photometry
We carry out a phase-curve analysis of the KELT-9 system using photometric observations from NASA's Transiting Exoplanet Survey Satellite (TESS). The measured secondary eclipse depth and peak-to-peak atmospheric brightness modulation are 650⁺¹⁴₋₁₅ and 566 ± 16 ppm, respectively. The planet's brightness variation reaches maximum 31 ± 5 minutes before the midpoint of the secondary eclipse, indicating a 5.°2 ± 0.°9 eastward shift in the dayside hot spot from the substellar point. We also detect stellar pulsations on KELT-9 with a period of 7.58695 ± 0.00091 hr. The dayside emission of KELT-9b in the TESS bandpass is consistent with a blackbody brightness temperature of 4600 ± 100 K. The corresponding nightside brightness temperature is 3040 ± 100 K, comparable to the dayside temperatures of the hottest known exoplanets. In addition, we detect a significant phase-curve signal at the first harmonic of the orbital frequency and a marginal signal at the second harmonic. While the amplitude of the first harmonic component is consistent with the predicted ellipsoidal distortion modulation assuming equilibrium tides, the phase of this photometric variation is shifted relative to the expectation. Placing KELT-9b in the context of other exoplanets with phase-curve observations, we find that the elevated nightside temperature and relatively low day–night temperature contrast agree with the predictions of atmospheric models that include H₂ dissociation and recombination. The nightside temperature of KELT-9b implies an atmospheric composition containing about 50% molecular and 50% atomic hydrogen at 0.1 bar, a nightside emission spectrum that deviates significantly from a blackbody, and a 0.5–2.0 μm transmission spectrum that is featureless at low resolution
TOI-2119: A transiting brown dwarf orbiting an active M-dwarf from NASA’s TESS mission
We report the discovery of TOI-2119b, a transiting brown dwarf (BD) that
orbits and is completely eclipsed by an active M-dwarf star. Using light curve
data from the Transiting Exoplanet Survey Satellite mission and follow-up
high-resolution Doppler spectroscopic observations, we find the BD has a radius
of , a mass of , an
orbital period of days, and an eccentricity of
. The host star has a mass of , a radius of , an effective
temperature of K, and a metallicity of . TOI-2119b joins an emerging population of transiting BDs
around M-dwarf host stars, with TOI-2119 being the ninth such system. These
M-dwarf--brown dwarf systems typically occupy mass ratios near , which separates them from the typical mass ratios for systems
with transiting substellar objects and giant exoplanets that orbit more massive
stars. The nature of the secondary eclipse of the BD by the star enables us to
estimate the effective temperature of the substellar object to be K, which is consistent with predictions by substellar evolutionary models.Comment: 14 pages, 13 figures, 4 tables, accepted in MNRA
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