316 research outputs found
Detecting Intracluster Gas Motion in Galaxy Clusters: Mock Astro-E2 Observations
We explore the detectability of bulk motions in the X-ray emitting
intracluster medium (ICM) using a catalog of 1,836 mock Astro-E2 observations
of simulated clusters of galaxies. We generate high resolution mock spectra for
two observing strategies: a four-pointing mosaic and a single central pointing.
Normalizing to 200 (400) photons in the iron K-alpha region for the mosaic
(central) study, we fit Poisson realizations of each simulated spectrum to a
velocity broadened isothermal plasma emission model. We confirm that the
velocity characteristics (mean and dispersion) returned by the spectral
fittings are unbiased measures of the emission-weighted values within the
observed region, with scatter 55 km/s. The maximum velocity difference between
mosaic element pairs has ~ 6% likelihood of being
transonic (), and the likelihood falls steeply,
p \spropto (\Delta v_{\rm max}/c_s)^{-4}, at high Mach number. The velocity
broadening parameter from the central pointing fit exceeds the
thermal value in 49% of the cases, with again a tail at large
dispersion. We present as case studies the clusters that yield the strongest
signal for each observing strategy.Comment: 13 pages, 20 figures. Submitted to ApJ. Version with postscript
figures embedded in the text available at
http://www.umich.edu/~apawl/astroe2/. Version 2 includes changes in response
to referee report and corrects an error in optical depth estimate
Simulation-Based Resuscitative Transesophageal Echocardiography Training for Emergency Medicine Residents
Introduction: Resuscitative TEE is an emerging tool in the cardiac arrest tool-box, and can improve outcomes in OHCA.
• Identifies reversible causes
• Decreases time off chest
• Evaluates compression efficacy
• Improves assessment during pulse-checks
• Simulation training can prepare EM residents to obtain and interpret TEE views on a live patient.https://knowledgeconnection.mainehealth.org/lambrew-retreat-2023/1008/thumbnail.jp
Systematic Evaluation of GPT-3 for Zero-Shot Personality Estimation
Very large language models (LLMs) perform extremely well on a spectrum of NLP
tasks in a zero-shot setting. However, little is known about their performance
on human-level NLP problems which rely on understanding psychological concepts,
such as assessing personality traits. In this work, we investigate the
zero-shot ability of GPT-3 to estimate the Big 5 personality traits from users'
social media posts. Through a set of systematic experiments, we find that
zero-shot GPT-3 performance is somewhat close to an existing pre-trained SotA
for broad classification upon injecting knowledge about the trait in the
prompts. However, when prompted to provide fine-grained classification, its
performance drops to close to a simple most frequent class (MFC) baseline. We
further analyze where GPT-3 performs better, as well as worse, than a
pretrained lexical model, illustrating systematic errors that suggest ways to
improve LLMs on human-level NLP tasks.Comment: Short Paper (5 pages), Accepted to (WASSA) 13th Workshop on
Computational Approaches to Subjectivity, Sentiment & Social Media Analysis
at ACL 202
The Distance to NGC 2264
We determine the distance to the open cluster NGC 2264 using a statistical
analysis of cluster member inclinations. We derive distance-dependent values of
sin i (where i is the inclination angle) for 97 stars in NGC 2264 from the
rotation periods, luminosities, effective temperatures, and projected
equatorial rotation velocities, v sin i, measured for these stars. We have
measured 96 of the v sin i values in our sample by analyzing high-resolution
spectra with a cross-correlation technique. We model the observed distribution
of sin i for the cluster by assuming that member stars have random axial
orientations and by adopting prescriptions for the measurement errors in our
sample. By adjusting the distance assumed in the observed sin i distribution
until it matches the modeled distribution, we obtain a best-fit distance for
the cluster. We find the data to be consistent with a distance to NGC 2264 of
913 pc. Quantitative tests of our analysis reveals uncertainties of 40 and 110
pc due to sampling and systematic effects, respectively. This distance estimate
suggests a revised age for the cluster of 1.5 Myrs, although more detailed
investigations of the full cluster membership are required to draw strong
conclusions.Comment: 12 pages, 11 figure
THE POTENTIAL EFFECT OF MINI-TRAMPOLINE STIFFNESS ON TAKE-OFF BEHAVIOUR OF GYMNASTS – A METHODOLOGICAL STUDY
The purpose of this study was to compare two mini-trampolines with different spring constant in regard to their effect on take-off mechanics. It was expected that the softer (36 springs) trampoline would lead to a longer contact time and a higher take-off impulse. To assess reaction forces during jumps a flexible force insole was used simultaneously with the measurement of run-in velocity by timing gates. Results showed no significant differences in contact mechanics or contact time indicating that the difference between these two trampolines is only marginal. Therefore, this study provides mainly a novel measurement approach to assess the effect of equipment changes in trampolining. Future studies are warranted to assess the athlete-equipment interaction in greater detail
- …