4,607 research outputs found
A Study of Optical Observing Techniques for Extra-Galactic Supernova Remnants: Case of NGC 300
We present the results of a study of observational and identification
techniques used for surveys and spectroscopy of candidate supernova remnants
(SNRs) in the Sculptor Group galaxy NGC 300. The goal of this study was to
investigate the reliability of using [Sii]/Halpha > 0.4 in optical SNR surveys
and spectra as an identifying feature of extra-galactic SNRs (egSNRs) and also
to investigate the effectiveness of the observing techniques (which are
hampered by seeing conditions and telescope pointing errors) using this
criterion in egSNR surveys and spectrographs. This study is based on original
observations of these objects and archival data obtained from the Hubble Space
Telescope which contained images of some of the candidate SNRs in NGC 300. We
found that the reliability of spectral techniques may be questionable and very
high-resolution images may be needed to confirm a valid identification of some
egSNRs.Comment: 27 Figures, 10 table
Reducing Postoperative Opioids After Minimally Invasive Gynecologic Surgery with Multimodal Pain Control
Introduction:
We evaluated the efficacy of a multimodal pain regimen that approaches pain control by utilizing different mechanisms of action. This novel protocol utilizing liposomal bupivacaine, acetaminophen, tramadol and oxycodone as needed in reducing the overall opioid use by patients after undergoing robotic-assisted total laparoscopic hysterectomy in an obese population that is heavily afflicted by the opioid epidemic.
Materials and Methods:
We conducted a retrospective study wherein a sample of 100 (50 multimodal group and 50 controls) were taken from 433 eligible cases conducted over a 1 year period. Patient medical records were evaluated for demographics, surgical characteristics, opioid type and dose, pain scores, length of stay and complications. Opioids were converted to oral morphine dose equivalents.
Results:
Overall opioid use in the multimodal group decreased by 54% (75.1mg versus 35.5mg, p
Discussion:
A multimodal approach to pain control is an acceptable alternative to traditional methods of pain control, regardless of BMI, for those with benign or malignant disease and decreases opioid use by 44 to 62 percent with no concomitant increase in pain scores and may decrease pain by 9 to 24 percent
Taxonomomy of Disinformation
Disinformation permeates science through individuals, organizations, and
governments that manipulate scholarly communication, media, and institutions.
This new taxonomy provides a framework and language to explain the actors,
outlets, and methods. For example, scholars recently published misinformation
about COVID-19 vaccines in a peer-reviewed journal. Now retracted, an author
reposted the debunked claims as legitimate research on their website. This case
demonstrates how the credibility of a professor's website can be exploited to
introduce falsehoods, and how bad actors circumvent corrections. With clarity
on the nature and flow of scientific disinformation, journalists and
policymakers can better identify and respond.Comment: 10 pages, 3 table
Hubble Space Telescope Imaging of the Ultracompact Blue Dwarf Galaxy HS 0822+3542: An Assembling Galaxy in a Local Void?
We present deep U, narrow-V, and I-band images of the ultracompact blue dwarf
galaxy HS 0822+3542, obtained with the Advanced Camera for Surveys / High
Resolution Channel of the Hubble Space Telescope. This object is extremely
metal-poor (12 + log(O/H) = 7.45) and resides in a nearby void. The images
resolve it into two physically separate components that were previously
described as star clusters in a single galaxy. The primary component is only
\~100 pc in maximum extent, and consists of starburst region surrounded by a
ring-like structure of relatively redder stars. The secondary component is ~50
pc in size and lies at a projected distance of ~80 pc away from the primary,
and is also actively star-forming. We estimate masses ~10^7 M(sol) and ~10^6
M(sol) for the two components, based on their luminosities, with an associated
dynamical timescale for the system of a few Myr. This timescale and the
structure of the components suggests that a collision between them triggered
their starbursts. The spectral energy distributions of both components can be
fitted by the combination of recent (few Myr old) starburst and an evolved
(several Gyr old) underlying stellar population, similar to larger blue compact
dwarf galaxies. This indicates that despite its metal deficiency the object is
not forming its first generation of stars. However, the small sizes and masses
of the two components suggests that HS 0822+3542 represents a dwarf galaxy in
the process of assembling from clumps of stars intermediate in size between
globular clusters and objects previously classified as galaxies. Its relatively
high ratio of neutral gas mass to stellar mass (~1) and high specific star
formation rate, log(SFR/M(sol) = -9.2, suggests that it is still converting
much of its gas to stars.Comment: 11 pages, 2 figures, accepted for publication in Astrophysical
Journal Letter
Physics of windblown particles
A laboratory facility proposed for the Space Station to investigate fundamental aspects of windblown particles is described. The experiments would take advantage of the environment afforded in earth orbit and would be an extension of research currently being conducted on the geology and physics of windblown sediments on earth, Mars, and Venus. Aeolian (wind) processes are reviewed in the planetary context, the scientific rational is given for specific experiments to be conducted, the experiment apparatus (the Carousel Wind Tunnel, or CWT) is described, and a plan presented for implementing the proposed research program
Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C391
Using the IRAM 30-m telescope, we observed the supernova remnant 3C 391
(G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2),
and CS(5-4) lines. The ambient molecular gas at the distance (9 kpc) of the
remnant comprises a giant molecular cloud whose edge is closely parallel to a
ridge of bright non-thermal radio continuum, which evidently delineates the
blast-wave into the cloud. We found that in a small (0.6 pc) portion of the
radio shell, the molecular line profiles consist of a narrow (2 km/s)
component, plus a very wide (> 20 km/s) component. Both spectral components
peak within 20" of a previously-detected OH 1720 MHz maser. We name this source
3C 391:BML (broad molecular line); it provides a new laboratory, similar to IC
443 but on a larger scale, to study shock interactions with dense molecular
gas. The wide spectral component is relatively brighter in the
higher-excitation lines. We interpret the wide spectral component as post-shock
gas, either smoothly accelerated or partially dissociated and reformed behind
the shock. The narrow component is either the pre-shock gas or cold gas
reformed behind a fully dissociative shock. Using the 3 observed CS lines, we
measured the temperature, CS column density, and H2 volume density in a dense
clump in the parent molecular cloud as well as the wide-line and narrow-line
portions of the shocked clump. The physical conditions of the narrow-line gas
are comparable to the highest-density clumps in the giant molecular cloud,
while the wide-line gas is both warmer and denser. The mass of compressed gas
in 3C 391:BML is high enough that its self-gravity is significant, and
eventually it could form one or several stars
- …