5,886 research outputs found
The Mass-to-Light Ratios of the Draco and Ursa Minor Dwarf Spheroidal Galaxies. II. The Binary Population and Its Effect in the Measured Velocity Dispersions of Dwarf Spheroidal Galaxies
We use a large set of radial velocities in the Ursa Minor and Draco dwarf
spheroidal galaxies to search for binary stars and to infer the binary
frequency. Of the 118 stars in our sample with multiple observations, six are
velocity variables with probabilities below 0.001. We use Monte Carlo
simulations that mimic our observations to determine the efficiency with which
our observations find binary stars. Our best, though significantly uncertain,
estimate of the binary frequency for stars near the turnoff in Draco and UMi is
0.2--0.3 per decade of period in the vicinity of periods of one year, which is
3--5 that found for the solar neighborhood. This frequency is high
enough that binary stars might significantly affect the measured velocity
dispersions of some dwarf spheroidal galaxies according to some previous
numerical experiments. However, in the course of performing our own
experiments, we discovered that this previous work had inadvertently
overestimated binary orbital velocities. Our first set of simulations of the
effects of binaries is based on the observed scatter in the individual velocity
measurements for the multiply-observed Draco and Ursa Minor stars. This scatter
is small compared to measured velocity dispersions and, so, the effect of
binaries on the dispersions is slight. This result is supported by our second
set of experiments, which are based on a model binary population normalized by
the observed binary frequency in Draco and Ursa Minor. We conclude that binary
stars have had no significant effect on the measured velocity dispersion and
inferred mass-to-light ratio of any dwarf spheroidal galaxy.Comment: 33 pages, 95kb uuencoded, gzipped postscript; Accepted by
Astronomical Journal; gzipped, tarred postscript of text, tables, figures
available at ftp://as.arizona.edu/pub/edo (binaries_in_dsph.tar.gz
Perioperative Glycemic Management
Proposals and Goals:
1. We propose creating a standard easy to use and safe protocol for glycemic management for same day/elective surgical patients.
2. Following implementation in same day and elective surgical procedures, we propose expanding the protocol to be effective in urgent and emergent inpatient surgical procedures.https://jdc.jefferson.edu/patientsafetyposters/1068/thumbnail.jp
Ambulation protocols leading to decreased postoperative complications and hospital stay
Background:
In the postoperative course, patients are routinely encouraged to ambulate as frequently as possible. Typically in the hospital this can become burdensome to the staff and often becomes low priority. Patients are also not aware of the frequency and quality of the ambulation that is sufficient in the postoperative period. At present, patients on the surgical floor who are completely independent and without any devices (eg. Oxygen, nasogastric tubes, chest tubes) are freely able to ambulate at will although there is no reliable way to track this progress. Other patients with devices are limited to waiting for nursing or ancillary staff to assist them with securing the devices that they require in the postoperative period. Ambulation has been positively associated with decreased postoperative complications ranging from bowel function to deep venous thrombosis to pneumonia.https://jdc.jefferson.edu/patientsafetyposters/1065/thumbnail.jp
Standardized Consent Forms for Surgical Procedures: An Intervention to Improve the Resident-led Informed Consent Process
Objectives and Goals:
To provide high quality, consistent consent forms for common surgical procedures and improve resident workflow by creating and implementing standardized printed consents for common surgical procedures.
These consents will be used by residents consenting patients in the ED or inpatient setting.
Consents shall include standardized procedure descriptions, risks and benefits of the procedure, and alternative treatment option descriptions, risks and benefitshttps://jdc.jefferson.edu/patientsafetyposters/1057/thumbnail.jp
The Science behind a flipped classroom
Paper presented at the 3rd Strathmore International Mathematics Conference (SIMC 2015), 3 - 7 August 2015, Strathmore University, Nairobi, Kenya.When first asked to teach a flipped classroom, I was excited and apprehensive at the same time. I knew I always wanted to try it but I wasn’t sure what the best practices were nor which parts of the class should be flipped and which shouldn’t. I soon found out there is a lot more to flipping a classroom, but the results can be rewarding. In this paper, I will describe how I flipped a College Algebra class with a specific focus for nursing students. In addition, valuable ideas and best practices on how to effectively flip a class are presented
Photometry and spectroscopy of faint candidate spectrophotometric standard DA white dwarfs
We present precise photometry and spectroscopy for 23 candidate
spectrophotometric standard white dwarfs. The selected stars are distributed in
the Northern hemisphere and around the celestial equators and are all fainter
than r ~ 16.5 mag. This network of stars, when established as standards,
together with the three Hubble Space Telescope primary CALSPEC white dwarfs,
will provide a set of spectrophotometric standards to directly calibrate data
products to better than 1%. These new faint standard white dwarfs will have
enough signal-to-noise ratio in future deep photometric surveys and facilities
to be measured accurately while still avoiding saturation in such surveys. They
will also fall within the dynamic range of large telescopes and their
instruments for the foreseeable future. This paper discusses the provenance of
the observational data for our candidate standard stars. The comparison with
models, reconciliation with reddening, and the consequent derivation of the
full spectral energy density distributions for each of them is reserved for a
subsequent paper.Comment: 31 pages, 17 figures, 10 tables, ApJ in press (accepted on December
23rd, 2018
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