6,531 research outputs found
Spatially and Spectrally Resolved Hydrogen Gas within 0.1 AU of T Tauri and Herbig Ae/Be Stars
We present near-infrared observations of T Tauri and Herbig Ae/Be stars with
a spatial resolution of a few milli-arcseconds and a spectral resolution of
~2000. Our observations spatially resolve gas and dust in the inner regions of
protoplanetary disks, and spectrally resolve broad-linewidth emission from the
Brackett gamma transition of hydrogen gas. We use the technique of
spectro-astrometry to determine centroids of different velocity components of
this gaseous emission at a precision orders of magnitude better than the
angular resolution. In all sources, we find the gaseous emission to be more
compact than or distributed on similar spatial scales to the dust emission. We
attempt to fit the data with models including both dust and Brackett
gamma-emitting gas, and we consider both disk and infall/outflow morphologies
for the gaseous matter. In most cases where we can distinguish between these
two models, the data show a preference for infall/outflow models. In all cases,
our data appear consistent with the presence of some gas at stellocentric radii
of ~0.01 AU. Our findings support the hypothesis that Brackett gamma emission
generally traces magnetospherically driven accretion and/or outflows in young
star/disk systems.Comment: 48 pages, including 17 figures. Accepted for publication by Ap
The complementarity of astrometric and radial velocity exoplanet observations - Determining exoplanet mass with astrometric snapshots
We obtain full information on the orbital parameters by combining radial
velocity and astrometric measurements by means of Bayesian inference. We sample
the parameter probability densities of orbital model parameters with a Markov
chain Monte Carlo (McMC) method in simulated observational scenarios to test
the detectability of planets with orbital periods longer than the observational
timelines. We show that, when fitting model parameters simultaneously to
measurements from both sources, it is possible to extract much more information
from the measurements than when using either source alone. We demonstrate this
by studying the orbit of recently found extra-solar planet HD 154345 b.Comment: 6 pages, 9 figures. Accepted to A&
Reality Capture Course Content: Exposing the Next Generation of Builders to Technology Moving the Industry Forward
This paper discusses the development and execution of lecture and laboratory educational content regarding reality capture technology and workflows. These educational modules were created to cover different use cases for reality capture technology that are currently being used in the construction industry. They also show how reality capture plays a role in the larger virtual design in construction (BIM) process. Importantly, these labs were designed to be completed with the LiDAR scanner on a typical iPhone, which has lowered the barrier to entry for reality capture education and use in industry. While the initial teaching of these courses was done in a synchronous in person format, content was also created to allow for these lessons to be completed asynchronously and remote, to provide students and faculty flexibility. This adds to the knowledge base of students in higher education by teaching elements of the BIM process not typically covered in a standard curriculum. The goal of this project was to provide a hands-on project for students, and faculty to understand how BIM can be used, and is currently being used on construction jobsites
First L-band Interferometric Observations of a Young Stellar Object: Probing the Circumstellar Environment of MWC 419
We present spatially-resolved K- and L-band spectra (at spectral resolution R
= 230 and R = 60, respectively) of MWC 419, a Herbig Ae/Be star. The data were
obtained simultaneously with a new configuration of the 85-m baseline Keck
Interferometer. Our observations are sensitive to the radial distribution of
temperature in the inner region of the disk of MWC 419. We fit the visibility
data with both simple geometric and more physical disk models. The geometric
models (uniform disk and Gaussian) show that the apparent size increases
linearly with wavelength in the 2-4 microns wavelength region, suggesting that
the disk is extended with a temperature gradient. A model having a power-law
temperature gradient with radius simultaneously fits our interferometric
measurements and the spectral energy distribution data from the literature. The
slope of the power-law is close to that expected from an optically thick disk.
Our spectrally dispersed interferometric measurements include the Br gamma
emission line. The measured disk size at and around Br gamma suggests that
emitting hydrogen gas is located inside (or within the inner regions) of the
dust disk.Comment: Accepted for publication in Ap
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Prevalence rates of drug use among school bullies and victims: A systematic review and meta-analysis of cross-sectional studies
This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.avb.2015.05.004Bullying is a common aggressive behaviour in school, with a number of cross-sectional studies showing that it exhibits a high comorbidity with other problem behaviours. The present study aims to estimate the comorbidity of school bullying (perpetration and victimisation) with drug use by incorporating and meta-analysing all available evidence on the cross-sectional association between the two variables. Meta-analytic results are based on a comprehensive systematic review across 20 databases and 46 journals. A total of 61 relevant manuscripts were included in the systematic review. Following explicit methodological criteria for the inclusion/exclusion of reports, 13 of them were eligible for the meta-analysis. The association of school bullying perpetration with drug use (adjusted odds ratio OR = 2.82; 95% CI 1.97–4.02; z = 5.71; p < .001) suggests a very strong relationship. For example, if a quarter of children were bullies and a quarter were drug users, this value of the OR would correspond to 40.88% of bullies being also drug users, compared with 19.71% of non-bullies. The association of school bullying victimisation with drug use (adjusted odds ratio OR = 1.79; 95% CI 1.38–2.32; z = 4.41; p < .001) suggests a moderate relationship. For example, if a quarter of children were victims and a quarter were drug users, this value of the OR would correspond to 33.69% of bullied youth also being drug users, compared with 22.1% of non-bullied youth. Adjusted effect sizes are based on study findings that used statistical controls for confounding variables, thus providing the unique association of school bullying with drug use over and above other important risk factors that may explain this association. Implications for policy and intervention research arising from this review are highlighted
A little more conversation, a little less action: Candidate roles for motor cortex in speech perception
The motor theory of speech perception assumes that activation of the motor system is essential in the perception of speech. However, deficits in speech perception and comprehension do not arise from damage that is restricted to the motor cortex, few functional imaging studies reveal activity in motor cortex during speech perception, and the motor cortex is strongly activated by many different sound categories. Here, we evaluate alternative roles for the motor cortex in spoken communication and suggest a specific role in sensorimotor processing in conversation. We argue that motor-cortex activation it is essential in joint speech, particularly for the timing of turn-taking
The role of source and filter cues in emotion recognition in speech [Abstract]
In the context of the source-filter theory of speech, it is well established that intelligibility is heavily reliant on information carried by the filter, that is, spectral cues (e.g., Faulkner et al., 2001; Shannon et al., 1995). However, the extraction of other types of information in the speech signal, such as emotion and identity, is less well understood. In this study we investigated the extent to which emotion recognition in speech depends on filterdependent cues, using a forced-choice emotion identification task at ten levels of noise-vocoding ranging between one and 32 channels. In addition, participants performed a speech intelligibility task with the same stimuli. Our results indicate that compared to speech intelligibility, emotion recognition relies less on spectral information and more on cues typically signaled by source variations, such as voice pitch, voice quality, and intensity. We suggest that, while the reliance on spectral dynamics is likely a unique aspect of human speech, greater phylogenetic continuity across species may be found in the communication of affect in vocalizations
Intraoperative Indocyanine Green Laser Angiography in Pediatric Autologous Ear Reconstruction.
Skin flap vascularity is a critical determinant of aesthetic results in autologous ear reconstruction. In this study, we investigate the use of intraoperative laser-assisted indocyanine green angiography (ICGA) as an adjunctive measure of skin flap vascularity in pediatric autologous ear reconstruction. Twenty-one consecutive pediatric patients undergoing first-stage autologous total ear reconstruction were retrospectively evaluated. The first 10 patients were treated traditionally (non-ICGA), and the latter 11 patients were evaluated with ICGA intraoperatively after implantation of the cartilage construct and administration of suction. Relative and absolute perfusion units in the form of contour maps were generated. Statistical analyses were performed using independent sample Student t test. Statistically significant differences in exposure and infection were not found between the 2 groups. However, decreased numbers of surgical revisions were required in cases with ICGA versus without ICGA (P = 0.03), suggesting that greater certainty in skin flap perfusion correlated with a reduction in revision surgeries. In cases of exposure, we found an average lowest absolute perfusion unit of 14.3, whereas cases without exposure had an average of 26.1 (P = 0.02), thereby defining objective parameters for utilizing ICGA data in tailoring surgical decision making for this special population of patients. Defined quantitative parameters for utilizing ICGA in evaluating skin flap vascularity may be a useful adjunctive technique in pediatric autologous ear reconstruction
Water for utilities: climate change impacts on water quality and water availability for utilities in Europe
This report provides an assessment of the consequences of changing water availability for production of drinking water, the manufacturing industry and power production in Europe, due to climate change and socio-economic developments. The report is based up on projections of demographic and socio-economic trends and climate change impacts, according to the SRES A2 and B1 scenario’s also used by IPC
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