Kentucky Space Grant Consortium

ABSTRACT: Apart from respiratory symptoms, encephalopathy and a range of central nervous system complications have been described in coronavirus disease 2019. However, there is a lack of published literature on the rehabilitative course and functional outcomes of severe coronavirus disease 2019 with encephalopathy. In addition, the presence of subclinical neurocognitive sequelae during postacute rehabilitation has not been described and may be underrecognized by rehabilitation providers. We report the rehabilitative course of a middle-aged male patient with severe coronavirus disease 2019 who required intensive care and mechanical ventilation. During postacute inpatient rehabilitation for severe intensive care unit-related weakness, an abnormal cognitive screen prompted brain magnetic resonance imaging, which revealed destructive leukoencephalopathy. Subsequently, detailed psychometric evaluation revealed significant impairments in the domains of processing speed and executive function. After 40 days of intensive inpatient rehabilitation, he was discharged home with independent function. This report highlights the need for an increased awareness of covert subclinical neurocognitive sequelae, the role of comprehensive rehabilitation, and value of routine cognitive screening therein and describes the neurocognitive features in severe COVID-19.

We present a multi‐wavelength examination of the disk and environment of the near‐ZAMS Herbig Ae star HD 100453 A. Chandra ACIS‐S imagery shows that the Herbig Ae star has Lx/Lbol and a pulse height spectrum similar to β Pic Moving Group early F stars, suggesting a similar magnetic field configuration and X‐ray production in winds. The disk lacks the conspicuous Fe II emission and continuum seen in FUV spectra of actively accreting Herbig Ae stars, and FUSE, HST ACS FUV, and FEROS data suggest a 3σ upper limit on accretion rate of 4.0×10−10 M⊙ yr−1. Weak, variable Hα and Brγ emission suggest low levels of intermittent accretion or contamination by stellar activity. We confirm that HD 100453 B is a common proper motion companion to HD 100453 A, with a spectral type of M4.0V—M4.5V, and derive an age of 14±4 Myr. It is likely the companion has truncated the circumprimary disk radius at less than ∼50 AU, and we estimate the dust mass to be ∼0.1 MJ. A sensitive upper limit to the CO J = 3–2 intensity indicates that the gas in the outer disk is likely optically thin. Assuming a [CO]/[H2] abundance of 1×10−4 and a depletion factor of 103, we find that the mass of cold molecular gas is less than ∼0.33 MJ and that the gas‐to‐dust ratio is no more than ∼4:1 in the outer disk.

Herbig Ae stars are young stars usually surrounded by gas and dust in the form of a disk and are thought to evolve into planetary systems similar to our own. We present a multi-wavelength examination of the disk and environment of the Herbig Ae star HD 100453A, focusing on the determination of accretion rate, system age, and disk evolution. We show that the accretion rate is characterized by Chandra X-ray imagery that is inconsistent with strongly accreting early F stars, that the disk lacks the conspicuous Fe II emission and continuum seen in FUV spectra of actively accreting Herbig Ae stars, and that FUSE, HST, and FEROS data suggest an accretion rate below ~2.5x10[to the power of -10] M[solar symbol] yr[to the power of -1]. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with spectral type M4.0V - M4.5V, and derive an age of 14 ± 4 Myr. We examine the Meeus et al. (2001) hypothesis that Meeus Group I sources, which have a mid-IR bump which can be fitted by a black body component, evolve to Meeus Group II sources, which have no such mid-IR bump. By considering stellar age and accretion rate evidence, we find the hypothesis to be invalid. Furthermore, we find that the disk characteristics of HD 100453A do not fit the traditional definition of a protoplanetary disk, a transitional disk, or a debris disk, and they may suggest a new class of disks linking gas-rich protoplanetary disks and gas-poor debris disks.