576 research outputs found
D-branes and Fat Black Holes
The application of D-brane methods to large black holes whose Schwarzschild
radius is larger than the compactification scale is problematic. Callan and
Maldacena have suggested that despite apparent problems of strong interactions
when the number of branes becomes large, the open string degrees of freedom may
remain very dilute due to the growth of the horizon area which they claim grows
more rapidly than the average number of open strings. Such a picture of a
dilute weakly coupled string system conflicts with the picture of a dense
string-soup that saturates the bound of one string per planck area. A more
careful analysis shows that Callan and Maldacena were not fully consistent in
their estimates. In the form that their model was studied it can not be used to
extrapolate to large mass without being in conflict with the Hawking Bekenstein
entropy formula. A somewhat modified model can reproduce the correct entropy
formula. In this ``improved model" the number of string bits on the horizon
scales like the entropy in agreement with earlier speculations of Susskind.Comment: 12 pages, uses phyzz
Is There Benefit in Keeping Early Discharge Patients Overnight After Total Joint Arthroplasty?
Introduction: In recent years, cost containment relative to patent safety and quality of care for total joint arthroplasty (TJA) has been a key focus for the Centers for Medicare and Medicaid Services (CMS) spawning significant research and programmatic change, including a move toward early discharge and outpatient TJA. TJA outpatients receive few, if any, medical interventions prior to discharge, but the type and quantity of medical interventions provided for TJA patients who stay overnight in the hospital is unknown. This study quantified the nature, frequency, and outcome of interventions occurring overnight after primary TJA.
Methods: 1,725 consecutive primary unilateral TJAs performed between 2012 and 2017 by a single surgeon in a rapid-discharge program, managed by a perioperative internal medicine specialist, were reviewed. Medical records were examined for diagnostic tests, treatments, and procedures performed, results of interventions, and all-cause readmissions. Recorded interventions included any that varied from the preoperative treatment plan, were beyond standard-of-care, and could not be completed at home.
Results: 759 patients were discharged on postoperative day one. 84% (641/759) received no medical interventions during their overnight hospital stay. Twelve (1.6%) received diagnostic tests, 90 (11.9%) received treatments, and 29 (3.8%) received procedures. 92% (11/12) of diagnostic tests were negative, 66% of 100 treatments in 90 patients were intravenous fluids for oliguria or hypotension, and all procedures were in/out catheterizations for urinary retention. 90-day all cause readmission rates were similar in patients who received (2.5%) and did not receive (3.3%) a clinical intervention.
Conclusion: The majority of patients received no overnight interventions, suggesting unnecessary costly hospitalization. The most common issues addressed were oliguria, urinary retention, and hypotension. Protocols to prevent these conditions would facilitate outpatient TJA, improve patient safety, and reduce costs.This research was supported by the Indiana University Health â Indiana School of Medicine Strategic Research Initiative
An Upper Mass Limit on a Red Supergiant Progenitor for the Type II-Plateau Supernova SN 2006my
We analyze two pre-supernova (SN) and three post-SN high-resolution images of
the site of the Type II-Plateau supernova SN 2006my in an effort to either
detect the progenitor star or to constrain its properties. Following image
registration, we find that an isolated stellar object is not detected at the
location of SN 2006my in either of the two pre-SN images. In the first, an
I-band image obtained with the Wide-Field and Planetary Camera 2 on board the
Hubble Space Telescope, the offset between the SN 2006my location and a
detected source ("Source 1") is too large: > 0.08", which corresponds to a
confidence level of non-association of 96% from our most liberal estimates of
the transformation and measurement uncertainties. In the second, a similarly
obtained V-band image, a source is detected ("Source 2") that has overlap with
the SN 2006my location but is definitively an extended object. Through
artificial star tests carried out on the precise location of SN 2006my in the
images, we derive a 3-sigma upper bound on the luminosity of a red supergiant
that could have remained undetected in our pre-SN images of log L/L_Sun = 5.10,
which translates to an upper bound on such a star's initial mass of 15 M_Sun
from the STARS stellar evolutionary models. Although considered unlikely, we
can not rule out the possibility that part of the light comprising Source 1,
which exhibits a slight extension relative to other point sources in the image,
or part of the light contributing to the extended Source 2, may be due to the
progenitor of SN 2006my. Only additional, high-resolution observations of the
site taken after SN 2006my has faded beyond detection can confirm or reject
these possibilities.Comment: Minor text changes from Version 1. Appendix added detailing the
determination of confidence level of non-association of point sources in two
registered astronomical image
Explaining the Praesepe blue straggler HD 73666
The blue straggler phenomenon is not yet well explained by current theory;
however, evolutionary models of star clusters call for a good knowledge of it.
Here we try to understand the possible formation scenario of HD 73666, a blue
straggler member of the Praesepe cluster. We compile the known physical
properties of HD 73666 found in the literature, focusing in particular on
possible binarity and the abundance pattern. HD 73666 appears to be slowly
rotating, has no detectable magnetic field, and has normal abundances, thereby
excluding close binary evolution and mass transfer processes. There is no
evidence of a hot radiation source. With the use of theoretical results on blue
straggler formation present in literature, we are able to conclude that HD
73666 was probably formed by physical collision involving at least one binary
system, between 5 and 350 Myr (50 Myr if the star is an intrinsic slow rotator)
ago.Comment: Accepted for publication on Astronomy and Astrophysic
The nature of the high Galactic latitude O-star HD93521: new results from X-ray and optical spectroscopy
Owing to its unusual location and its isolation, the nature of the high
Galactic latitude O9.5Vp object HD93521 is still uncertain. We have collected
X-ray and optical observations to characterize the star and its surroundings.
X-ray images and spectra are analyzed to search for traces of a recent star
formation event around HD93521 and to search for the signature of a possible
compact companion. Optical echelle spectra are analysed with plane-parallel
model atmosphere codes, assuming either a spherical star or a gravity darkened
rotationally flattened star, to infer the effective temperature and surface
gravity, and to derive the He, C, N and O abundances of HD93521. The X-ray
images reveal no traces of a population of young low-mass stars coeval with
HD93521. The X-ray spectrum of HD93521 is consistent with a normal late O-type
star although with subsolar metallicity. No trace of a compact companion is
found in the X-ray data. In the optical spectrum, He and N are found to be
overabundant, in line with the effect of rotational mixing in this very fast
rotator, whilst C and O are subsolar. A critical comparison with the properties
of subdwarf OB stars, indicates that, despite some apparent similarities,
HD93521 does not belong to this category. Despite some ambiguities on the
runaway status of the star, the most likely explanation is that HD93521 is a
Population I massive O-type star that was ejected from the Galactic plane
either through dynamical interactions or a result of a supernova event in a
binary system.Comment: Accepted for publication in Astronomy & Astrophysic
The Ursinus Weekly, November 8, 1973
Dr. Pancoast predicts much competition for teachers ⢠Civil service commission announces test dates ⢠Service organization shows true colors ⢠Christmas concert ⢠Campus Chest schedules fund raising activities ⢠Concert cancellation ⢠Editorial: When the life sciences become the death sciences ⢠Letters to the editor: Beef over rhetoric; Physics dept. maintains status quo; A plea for silence; What are we doing here? ⢠Alumni corner ⢠Faculty Portrait: Mr. Ted Xaras ⢠The stage: ProTheatre begins year with three one-act plays in new theatre ⢠A bundle of letters ⢠Film: âJeremyâ ⢠Third team goes undefeated! ⢠Football Bears tie, 21-21 ⢠Once beaten Harriers enter MAC championship ⢠Womenâs volleyball team into actionhttps://digitalcommons.ursinus.edu/weekly/1005/thumbnail.jp
Total Synthesis of Paracaseolide A
The total synthesis of paracaseolide A, a valuable cell-cycle progression inhibitor, was accomplished in 8 steps from known compounds, with 6.6% overall yield. The synthetic strategy creates strong potential for diversification
Nachhaltigkeit im industriellen Umfeld
Im Rahmen der Lehrveranstaltung "Nachhaltigkeit im industriellen Umfeld" im Masterstudiengang Umwelt- und Verfahrenstechnik der Hochschulen Konstanz und Ravensburg-Weingarten wurde 2015 eine studentische Fachkonferenz durchgefĂźhrt.
Die Studierenden entwickelten in Einzelarbeit oder als Zweierteam Konferenzbeiträge zu folgenden Themen:
- Innovationen und Spannendes aus dem Bereich der Energieerzeugung und -wandlung
- Aspekte der SchlieĂung von Stoffkreisläufen und Vermeidung von Schadstoffeinträgen in die Umwelt
- Chancen und Herausforderungen Nachwachsender Rohstoffe bei verschiedenen EinsatzmĂśglichkeiten sowie Themen der Nachhaltigkeit in der Landwirtschaft
- verschiedene Blickwinkel auf das Thema Wasser (von der Abwasserreinigung bis zum Wasserkonsum der Konsumenten)
- die Betrachtung spezifischer Industrien und Unternehmen sowie deren Werkzeuge zur Umsetzung von Nachhaltigkeit
Die Ergebnisse der studentischen Fachkonferenz zur âNachhaltigkeit im industriellen Umfeldâ werden in der vorliegenden Publikation präsentiert
An eddy permitting coupled physical-biological model of the North Atlantic. Part I: Sensitivity to advection numerics and mixed layer physics
Physical influences on biological primary production in the North Atlantic are investigated by coupling a four-component pelagic ecosystem model with a high-resolution numerical circulation model. A series of sensitivity experiments demonstrates the important role of an accurate formulation of upper ocean turbulence and advection numerics. The unrealistically large diffusivity implicit in upstream advection approximately doubles primary production when compared with a less diffusive, higher-order, positive-definite advection scheme.This is of particular concern in the equatorial upwelling region where upstream advection leads to a considerable increase of upper ocean nitrate concentrations. Counteracting this effect of unrealistically large implicit diffusion by changes in the biological model could easily lead to misconceptions in the interpretation of ecosystem dynamics. Subgrid-scale diapycnal diffusion strongly controls biological production in the subtropical gyre where winter mixing does not reach the nutricline. The parameterization of vertical viscosity is important mainly in the equatorial region where friction becomes an important agent in the momentum balance
- âŚ