34 research outputs found
The impact of comorbid anxiety on quantitative EEG heterogeneity in children with attention-deficit/hyperactivity disorder
ObjectiveThe objective of this study was to compare quantitative electroencephalography (Q-EEG) characteristics of children with Attention-deficit/hyperactivity disorder (ADHD), taking into account the presence of a comorbidity for anxiety disorder. It also sought to investigate the impact of comorbid anxiety on the Q-EEG heterogeneity of children with ADHD.MethodA total of 141 children with ADHD but without comorbid anxiety (ADHD-Only), 25 children with a comorbidity for anxiety disorder (ADHD-ANX) and 43 children in the control group were assessed. To compare Q-EEG characteristics between groups, we performed ANCOVA (Analysis of Covariance) on relative power and theta/beta ratio (TBR) controlling for covariates such as age, sex, and FSIQ. Relative power values from 19 electrodes were averaged for three regions (frontal, central and posterior). Furthermore, cluster analysis (Ward’s method) using the squared Euclidian distance was conducted on participants with ADHD to explore the impact of anxiety on the heterogeneity of Q-EEG characteristics in ADHD.ResultsThere were no significant group differences in cognitive and behavioral measures. However, significant differences between groups were observed in the theta values in the central region, and the beta values in the frontal, central and posterior regions. In post hoc analyses, It was found that the ADHD-ANX group has significantly higher beta power values than the ADHD-Only group in all regions. For the theta/beta ratio, the ADHD-Only group had significantly higher values than the ADHD-ANX group in frontal, central and posterior regions. However, the control group did not show significant differences compared to both the ADHD-Only and ADHD-ANX group. Through clustering analysis, the participants in the ADHD-Only and ADHD-ANX groups were classified into four clusters. The ratios of children with comorbidities for anxiety disorder within each cluster were significantly different (χ2 = 10.018, p = 0.019).ConclusionAttention-deficit/hyperactivity disorder children with comorbid anxiety disorder showed lower theta power in the central region, higher beta power in all regions and lower TBR in all regions compared to those without comorbid anxiety disorder. The ratios of children with comorbidities for anxiety disorder within each cluster were significantly different
MINDS. JWST-MIRI Reveals a Dynamic Gas-Rich Inner Disk Inside the Cavity of SY Cha
SY Cha is a T Tauri star surrounded by a protoplanetary disk with a large
cavity seen in the millimeter continuum but has the spectral energy
distribution (SED) of a full disk. Here we report the first results from
JWST-MIRI Medium Resolution Spectrometer (MRS) observations taken as part of
the MIRI mid-INfrared Disk Survey (MINDS) GTO Program. The much improved
resolution and sensitivity of MIRI-MRS compared to Spitzer enables a robust
analysis of the previously detected H2O, CO, HCN, and CO2 emission as well as a
marginal detection of C2H2. We also report the first robust detection of
mid-infrared OH and ro-vibrational CO emission in this source. The derived
molecular column densities reveal the inner disk of SY Cha to be rich in both
oxygen and carbon bearing molecules. This is in contrast to PDS 70, another
protoplanetary disk with a large cavity observed with JWST, which displays much
weaker line emission. In the SY Cha disk, the continuum, and potentially the
line, flux varies substantially between the new JWST observations and archival
Spitzer observations, indicative of a highly dynamic inner disk.Comment: 19 pages, 10 figures, 5 tables, accepted for publication in Ap
MINDS: The JWST MIRI Mid-INfrared Disk Survey
The study of protoplanetary disks has become increasingly important with the
Kepler satellite finding that exoplanets are ubiquitous around stars in our
galaxy and the discovery of enormous diversity in planetary system
architectures and planet properties. High-resolution near-IR and ALMA images
show strong evidence for ongoing planet formation in young disks. The JWST MIRI
mid-INfrared Disk Survey (MINDS) aims to (1) investigate the chemical inventory
in the terrestrial planet-forming zone across stellar spectral type, (2) follow
the gas evolution into the disk dispersal stage, and (3) study the structure of
protoplanetary and debris disks in the thermal mid-IR. The MINDS survey will
thus build a bridge between the chemical inventory of disks and the properties
of exoplanets. The survey comprises 52 targets (Herbig Ae stars, T Tauri stars,
very low-mass stars and young debris disks). We primarily obtain MIRI/MRS
spectra with high S/N (~100-500) covering the complete wavelength range from
4.9 to 27.9 {\mu}m. For a handful of selected targets we also obtain NIRSpec
IFU high resolution spectroscopy (2.87-5.27 {\mu}m). We will search for
signposts of planet formation in thermal emission of micron-sized dust -
information complementary to near-IR scattered light emission from small dust
grains and emission from large dust in the submillimeter wavelength domain. We
will also study the spatial structure of disks in three key systems that have
shown signposts for planet formation, TW Hya and HD 169142 using the MIRI
coronagraph at 15.5 {\mu}m and 10.65 {\mu}m respectively and PDS70 using NIRCam
imaging in the 1.87 {\mu}m narrow and the 4.8 {\mu}m medium band filter. ...Comment: accepted for publication in PAS
MINDS. Abundant water and varying C/O across the disk of Sz 98 as seen by JWST/MIRI
MIRI/MRS on board the JWST allows us to probe the inner regions of
protoplanetary disks. Here we examine the disk around the classical T Tauri
star Sz 98, which has an unusually large dust disk in the millimetre with a
compact core. We focus on the HO emission through both its ro-vibrational
and pure rotational emission. Furthermore, we compare our chemical findings
with those obtained for the outer disk from Atacama Large
Millimeter/submillimeter Array (ALMA) observations. In order to model the
molecular features in the spectrum, the continuum was subtracted and LTE slab
models were fitted. The spectrum was divided into different wavelength regions
corresponding to HO lines of different excitation conditions, and the slab
model fits were performed individually per region. We confidently detect CO,
HO, OH, CO, and HCN in the emitting layers. The isotopologue
HO is not detected. Additionally, no other organics, including
CH, are detected. This indicates that the C/O ratio could be
substantially below unity, in contrast with the outer disk. The HO emission
traces a large radial disk surface region, as evidenced by the gradually
changing excitation temperatures and emitting radii. The OH and CO emission
are relatively weak. It is likely that HO is not significantly
photodissociated; either due to self-shielding against the stellar irradiation,
or UV-shielding from small dust particles. The relative emitting strength of
the different identified molecular features point towards UV-shielding of
HO in the inner disk of Sz 98, with a thin layer of OH on top. The majority
of the organic molecules are either hidden below the dust continuum, or not
present. In general, the inferred composition points to a sub-solar C/O ratio
(<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in
the gas in the outer disk found with ALMA.Comment: Submitted to A&A on May 25 2023. 18 pages, 11 figure
MINDS. The detection of CO with JWST-MIRI indicates abundant CO in a protoplanetary disk
We present JWST-MIRI MRS spectra of the protoplanetary disk around the
low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey (MINDS) GTO
program. Emission from CO, CO, HO, HCN,
CH, and OH is identified with CO being detected for
the first time in a protoplanetary disk. We characterize the chemical and
physical conditions in the inner few au of the GW Lup disk using these
molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high
signal-to-noise data is essential to identify these species and determine their
column densities and temperatures. The -branches of these molecules,
including those of hot-bands, are particularly sensitive to temperature and
column density. We find that the CO emission in the GW Lup disk is
coming from optically thick emission at a temperature of 400 K.
CO is optically thinner and based on a lower temperature of
325 K, may be tracing deeper into the disk and/or a larger emitting
radius than CO. The derived /
ratio is orders of magnitude higher than previously derived for GW Lup and
other targets based on \textit{Spitzer}-IRS data. This high column density
ratio may be due to an inner cavity with a radius in between the HO and
CO snowlines and/or an overall lower disk temperature. This paper
demonstrates the unique ability of JWST to probe inner disk structures and
chemistry through weak, previously unseen molecular features.Comment: 15 pages, 10 figures. Accepted to ApJ
Growth after the streaming instability : The radial distance dependence of the planetary growth
Streaming instability is hypothesized to be triggered at particular protoplanetary disk locations where the volume density of the solid particles is enriched comparable to that of the gas. A ring of planetesimals thus forms when this condition is fulfilled locally. These planetesimals collide with each other and accrete inward drifting pebbles from the outer disk to further increase masses. We investigate the growth of the planetesimals that form in a ring-belt at various disk radii. Their initial mass distributions are calculated based on the formula summarized from the streaming instability simulations. We simulate the subsequent dynamical evolution of the planetesimals with a protoplanetary disk model based either on the minimum mass solar nebula (MMSN) or on the Toomre stability criterion. For the MMSN model, both pebble accretion and planetesimal accretion are efficient at a close-in orbit of 0.3 AU, resulting in the emergence of several super-Earth mass planets after 1 Myr. For comparison, only the most massive planetesimals undergo substantial mass growth when they are born at r = 3 AU, while the planetesimals at r = 30 AU experience little or no growth. On the other hand, in the denser Toomre disk, the most massive forming planets can reach Earth mass at t = 1 Myr and reach a mass between that of Neptune and that of Saturn within 3 Myr at 30 AU and 100 AU. Both the pebble and planetesimal accretion rate decrease with disk radial distance. Nevertheless, planetesimal accretion is less pronounced than pebble accretion at more distant disk regions. Taken together, the planets acquire higher masses when the disk has a higher gas density, a higher pebble flux, and/or a lower Stokes number of pebbles