136 research outputs found
An interferometric study of the Fomalhaut inner debris disk. I. Near-infrared detection of hot dust with VLTI/VINCI
The innermost parts of dusty debris disks around main sequence stars are
currently poorly known due to the high contrast and small angular separation
with their parent stars. Using near-infrared interferometry, we aim to detect
the signature of hot dust around the nearby A4 V star Fomalhaut, which has
already been suggested to harbor a warm dust population in addition to a cold
dust ring located at about 140 AU. Archival data obtained with the VINCI
instrument at the VLTI are used to study the fringe visibility of the Fomalhaut
system at projected baseline lengths ranging from 4 m to 140 m in the K band. A
significant visibility deficit is observed at short baselines with respect to
the expected visibility of the sole stellar photosphere. This is interpreted as
the signature of resolved circumstellar emission, producing a relative flux of
0.88% +/- 0.12% with respect to the stellar photosphere. While our
interferometric data cannot directly constrain the morphology of the excess
emission source, complementary data from the literature allow us to discard an
off-axis point-like object as the source of circumstellar emission. We argue
that the thermal emission from hot dusty grains located within 6 AU from
Fomalhaut is the most plausible explanation for the detected excess. Our study
also provides a revised limb-darkened diameter for Fomalhaut (2.223 +/- 0.022
mas), taking into account the effect of the resolved circumstellar emission.Comment: 13 pages, accepted for publication in Ap
The role of every-day executive function in social impairment and adaptive skills in Autism Spectrum Disorder with intellectual disability
Background:
Although executive function (EF) deficits are a recognised component of the cognitive phenotype of Autism Spectrum Disorder (ASD), particularly in children without general intellectual delay, little is known about ecological measures of EF and their outcome correlates among individuals with ASD and co-occurring intellectual disability. This exploratory study examined every-day EF in the classroom among children and adolescents diagnosed with both ASD and intellectual disability (ASD-ID) and their correlations with social impairment anadaptive functioning.
Method:
Teachers of 40 children and adolescents diagnosed with ASD-ID completed the
Behavior Rating Inventory of Executive Function, the Vineland Adaptive Behavior Scales, and the Social Responsiveness Scale.
Results:
A global executive dysfunction profile was found in ASD-ID, with most prominent deficits occurring in shifting. Results also showed that metacognitive executive processes predicted adaptive communication skills above and beyond IQ and social impairment in ASD-ID.
Conclusions:
Our findings corroborate a specific metacognitive executive function-adaptive communication association in ASD. EF interventions might be important treatment targets for improving functioning, especially in the communicative domain, in ASD-ID
Adaptive optics in high-contrast imaging
The development of adaptive optics (AO) played a major role in modern
astronomy over the last three decades. By compensating for the atmospheric
turbulence, these systems enable to reach the diffraction limit on large
telescopes. In this review, we will focus on high contrast applications of
adaptive optics, namely, imaging the close vicinity of bright stellar objects
and revealing regions otherwise hidden within the turbulent halo of the
atmosphere to look for objects with a contrast ratio lower than 10^-4 with
respect to the central star. Such high-contrast AO-corrected observations have
led to fundamental results in our current understanding of planetary formation
and evolution as well as stellar evolution. AO systems equipped three
generations of instruments, from the first pioneering experiments in the
nineties, to the first wave of instruments on 8m-class telescopes in the years
2000, and finally to the extreme AO systems that have recently started
operations. Along with high-contrast techniques, AO enables to reveal the
circumstellar environment: massive protoplanetary disks featuring spiral arms,
gaps or other asymmetries hinting at on-going planet formation, young giant
planets shining in thermal emission, or tenuous debris disks and micron-sized
dust leftover from collisions in massive asteroid-belt analogs. After
introducing the science case and technical requirements, we will review the
architecture of standard and extreme AO systems, before presenting a few
selected science highlights obtained with recent AO instruments.Comment: 24 pages, 14 figure
A narrow, edge-on disk resolved around HD 106906 with SPHERE
HD~106906AB is so far the only young binary system around which a planet has
been imaged and a debris disk evidenced thanks to a strong IR excess. As such,
it represents a unique opportunity to study the dynamics of young planetary
systems. We aim at further investigating the close (tens of au scales)
environment of the HD~106906AB system. We used the extreme AO fed, high
contrast imager SPHERE recently installed on the VLT to observe HD~106906. Both
the IRDIS imager and the Integral Field Spectrometer were used. We discovered a
very inclined, ring-like disk at a distance of 65~au from the star. The disk
shows a strong brightness asymmetry with respect to its semi-major axis. It
shows a smooth outer edge, compatible with ejection of small grains by the
stellar radiation pressure. We show furthermore that the planet's projected
position is significantly above the disk's PA. Given the determined disk
inclination, it is not excluded though that the planet could still orbit within
the disk plane if at a large separation (2000--3000 au). We identified several
additional point sources in the SPHERE/IRDIS field-of-view, that appear to be
background objects. We compare this system with other debris disks sharing
similarities, and we briefly discuss the present results in the framework of
dynamical evolution.Comment: 7 pages, 6 figures, accepted by Astronomy & Astrophysic
Post conjunction detection of Pictoris b with VLT/SPHERE
With an orbital distance comparable to that of Saturn in the solar system,
\bpic b is the closest (semi-major axis \,9\,au) exoplanet that has
been imaged to orbit a star. Thus it offers unique opportunities for detailed
studies of its orbital, physical, and atmospheric properties, and of
disk-planet interactions. With the exception of the discovery observations in
2003 with NaCo at the Very Large Telescope (VLT), all following astrometric
measurements relative to \bpic have been obtained in the southwestern part of
the orbit, which severely limits the determination of the planet's orbital
parameters. We aimed at further constraining \bpic b orbital properties using
more data, and, in particular, data taken in the northeastern part of the
orbit.
We used SPHERE at the VLT to precisely monitor the orbital motion of beta
\bpic b since first light of the instrument in 2014. We were able to monitor
the planet until November 2016, when its angular separation became too small
(125 mas, i.e., 1.6\,au) and prevented further detection. We redetected \bpic b
on the northeast side of the disk at a separation of 139\,mas and a PA of
30 in September 2018. The planetary orbit is now well constrained.
With a semi-major axis (sma) of au (1 ), it
definitely excludes previously reported possible long orbital periods, and
excludes \bpic b as the origin of photometric variations that took place in
1981. We also refine the eccentricity and inclination of the planet. From an
instrumental point of view, these data demonstrate that it is possible to
detect, if they exist, young massive Jupiters that orbit at less than 2 au from
a star that is 20 pc away.Comment: accepted by A&
Verbal thinking and inner speech use in autism spectrum disorder
The extent to which cognition is verbally mediated in neurotypical individuals is the subject of debate in cognitive neuropsychology, as well as philosophy and psychology. Studying âverbal thinkingâ in developmental/neuropsychological disorders provides a valuable opportunity to inform theory building, as well as clinical practice. In this paper, we provide a comprehensive, critical review of such studies among individuals with autism spectrum disorder (ASD). ASD involves severe social-communication deficits and limitations in cognitive/behavioural flexibility. The prevailing view in the field is that neither cognition nor behaviour is mediated verbally in ASD, and that this contributes to diagnostic features. However, our review suggests that, on the contrary, most studies to date actually find that among people with ASD cognitive task performance is either a) mediated verbally in a typical fashion, or b) not mediated verbally, but at no obvious cost to overall task performance. Overall though, these studies have methodological limitations and thus clear-cut conclusions are not possible at this stage. The aim of the review is to take stock of existing empirical findings, as well as to help develop the directions for future research that will resolve the many outstanding issues in this field
A planetary collision afterglow and transit of the resultant debris cloud
Stars and planetary system
Efficacy of praziquantel and artemisinin derivatives for the treatment and prevention of human schistosomiasis: a systematic review and meta-analysis
<p>Abstract</p> <p>Background</p> <p>Praziquantel has been used as first-line drug for chemotherapy of schistosomiasis since 1984. Besides praziquantel, artemether and artesunate have also been used for the control of this infectious disease since late 1990s. In this article, we conducted a systematic review and meta-analysis to evaluate the antischistosomal efficacy of different medication strategies including monotherapy or combination therapies of these drugs.</p> <p>Results</p> <p>A number of 52 trials from 38 articles published in peer-reviewed journals before July 2011 were selected for analysis after searching the following literature databases: the Cochrane Library, PubMed/Medline, ISI Web of Science, Chinese Biomedicine Literature Database, and China National Knowledge Infrastructure. Our meta-analyses showed that a dosage of 30-60 mg/kg praziquantel compared with placebo produced a protection rate of about 76% (95% CI: 67%-83%) for treating human schistosomiasis, which varied from 70% to 76% with no significant differences among the subspecies <it>S. haematobium</it>, <it>S. japonicum </it>or <it>S. mansoni</it>. Protection rates were higher when praziquantel doses were elevated, as concluded from the nRCTs results: the protection rate of praziquantel at 40 mg/kg was 52% (95% CI: 49%-55%), and it increased to 91% (95% CI: 88%-92%) when the dosages were elevated to 60/80/100 mg/kg divided two or more doses. Multiple doses of artemether or artesunate over 1- or 2-week intervals resulted in protection rates of 65% to 97% for preventing schistosomiasis, and increased doses and shorter medication intervals improved their efficacies. Praziquantel and artemisinin derivatives (artemether or artesunate) in combination resulted in a higher protection rate of 84% (95% CI: 64%-91%) than praziquantel monotherapy for treatment. praziquantel and artesunate in combination had a great protection rate of 96% (95% CI: 78%-99%) for preventing schistosomes infection.</p> <p>Conclusions</p> <p>According to the results, praziquantel remains effective in schistosomiasis treatment, and multiple doses would improve its efficacy; meanwhile, praziquantel is also a good drug for preventing acute schistosomiasis morbidity. It's better to use multiple doses of artemether or artesunate with 1- or 2-week intervals for prevention against schistosome infection. Praziquantel and artemether or artesunate in combination perform better in treatment than praziquantel monotherapy, and they are especially suitable for treating the patients with repeated exposure to infected water.</p
Time-Resolved FRET -Based Approach for Antibody Detection - A New Serodiagnostic Concept
Peer reviewe
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