12,772 research outputs found
The Mass, Orbit, and Tidal Evolution of the Quaoar-Weywot System
Here we present new adaptive optics observations of the Quaoar-Weywot system.
With these new observations we determine an improved system orbit. Due to a
0.39 day alias that exists in available observations, four possible orbital
solutions are available with periods of , , , and
days. From the possible orbital solutions, system masses of
kg are found. These observations provide an
updated density for Quaoar of 2.7-5.0{g cm^{-3}}. In all cases, Weywot's
orbit is eccentric, with possible values . We present a
reanalysis of the tidal orbital evolution of the Quoaor-Weywot system. We have
found that Weywot has probably evolved to a state of synchronous rotation, and
have likely preserved their initial inclinations over the age of the Solar
system. We find that for plausible values of the effective tidal dissipation
factor tides produce a very slow evolution of Weywot's eccentricity and
semi-major axis. Accordingly, it appears that Weywot's eccentricity likely did
not tidally evolve to its current value from an initially circular orbit.
Rather, it seems that some other mechanism has raised its eccentricity
post-formation, or Weywot formed with a non-negligible eccentricity.Comment: Accepted to Icarus, Nov. 8 201
Results from a VLT-ISAAC survey of ices and gas around young stellar objects
General results from a 3-5 micron spectroscopic survey of nearby low-mass
young stellar objects are presented. L and M-band spectra have been obtained of
\~50 low mass embedded young stars using the ISAAC spectrometer mounted on
UT1-Antu at Paranal Observatory. For the first time, a consistent census of the
CO, H2O ices and the minor ice species CH3OH and OCN- and warm CO gas present
around young stars is obtained, using large number statistics and resolving
powers of up to R=10000. The molecular structure of circumstellar CO ices, the
depletion of gaseous CO onto grains in protoplanetary disks, the presence of
hot gas in the inner parts of circumstellar disks and in outflows and infalls
are studied. Furthermore, the importance of scattering effects for the
interpretation of the spectra have been addressed.Comment: To appear in the proceedings of the conference "Chemistry as a
Diagnostic of Star Formation", University of Waterloo, Canada, 21-23 August
200
Prevalence and predictors of postdischarge antibiotic use following mastectomy
OBJECTIVESurvey results suggest that prolonged administration of prophylactic antibiotics is common after mastectomy with reconstruction. We determined utilization, predictors, and outcomes of postdischarge prophylactic antibiotics after mastectomy with or without immediate breast reconstruction.DESIGNRetrospective cohort.PATIENTSCommercially insured women aged 18–64 years coded for mastectomy from January 2004 to December 2011 were included in the study. Women with a preexisting wound complication or septicemia were excluded.METHODSPredictors of prophylactic antibiotics within 5 days after discharge were identified in women with 1 year of prior insurance enrollment; relative risks (RR) were calculated using generalized estimating equations.RESULTSOverall, 12,501 mastectomy procedures were identified; immediate reconstruction was performed in 7,912 of these procedures (63.3%). Postdischarge prophylactic antibiotics were used in 4,439 procedures (56.1%) with immediate reconstruction and 1,053 procedures (22.9%) without immediate reconstruction (P<.001). The antibiotics most commonly prescribed were cephalosporins (75.1%) and fluoroquinolones (11.1%). Independent predictors of postdischarge antibiotics were implant reconstruction (RR, 2.41; 95% confidence interval [CI], 2.23–2.60), autologous reconstruction (RR, 2.17; 95% CI, 1.93–2.45), autologous reconstruction plus implant (RR, 2.11; 95% CI, 1.92–2.31), hypertension (RR, 1.05; 95% CI, 1.00–1.10), tobacco use (RR, 1.07; 95% CI, 1.01–1.14), surgery at an academic hospital (RR, 1.14; 95% CI, 1.07–1.21), and receipt of home health care (RR, 1.11; 95% CI, 1.04–1.18). Postdischarge prophylactic antibiotics were not associated with SSI after mastectomy with or without immediate reconstruction (bothP>.05).CONCLUSIONSProphylactic postdischarge antibiotics are commonly prescribed after mastectomy; immediate reconstruction is the strongest predictor. Stewardship efforts in this population to limit continuation of prophylactic antibiotics after discharge are needed to limit antimicrobial resistance.Infect Control Hosp Epidemiol2017;38:1048–1054</jats:sec
Incidence of surgical site infection following mastectomy with and without immediate reconstruction using private insurer claims data
OBJECTIVE: The National Healthcare Safety Network classifies breast operations as clean procedures with an expected 1–2% surgical site infection (SSI) incidence. We assessed differences in SSI incidence following mastectomy with and without immediate reconstruction in a large, geographically diverse population. DESIGN: Retrospective cohort study. PATIENTS: Commercially-insured women aged 18–64 years with ICD-9-CM procedure or CPT-4 codes for mastectomy from 1/1/2004–12/31/2011. METHODS: Incident SSIs within 180 days after surgery were identified by ICD-9-CM diagnosis codes. The incidence of SSI after mastectomy +/− immediate reconstruction was compared by the chi-square test. RESULTS: From 2004–2011, 18,696 mastectomy procedures among 18,085 women were identified, with immediate reconstruction in 10,836 (58%) procedures. The 180-day incidence of SSI following mastectomy with or without reconstruction was 8.1% (1,520/18,696). Forty-nine percent of SSIs were identified within 30 days post-mastectomy, 24.5% between 31–60 days, 10.5% between 61–90 days, and 15.7% between 91–180 days. The incidence of SSI was 5.0% (395/7,860) after mastectomy-only, 10.3% (848/8,217) after mastectomy plus implant, 10.7% (207/1,942) after mastectomy plus flap, and 10.3% (70/677) after mastectomy plus flap and implant (p<0.001). The SSI risk was higher after bilateral compared with unilateral mastectomy with (11.4% vs. 9.4%, p=0.001) and without (6.1% vs. 4.7%, p=0.021) immediate reconstruction. CONCLUSIONS: SSI incidence was two-fold higher after mastectomy with immediate reconstruction than after mastectomy alone. Only 49% of SSIs were coded within 30 days after operation. Our results suggest stratification by procedure type will facilitate comparison of SSI rates after breast operations between facilities
The Urban Political Ecology of Post-industrial Scottish Towns: Examining Greengairs and Ravenscraig
Urban ecological politics is shaped by both moments of concerted action and more silent perceptions and responses. Instead of only being evident in situations of organised protest, the politics of urban ecology is also manifested, in material and symbolic terms, in the daily life of the residents. The fragmentation of urban political ecology turns out to be an important element in the affirmation of post-political forms of urban governance. Those issues were the object of fieldwork research carried out in Greengairs and Ravenscraig, two towns in North Lanarkshire, near Glasgow, with the goal of unravelling the understanding and the coping mechanisms of environmentally deprived residents. The towns are permeated by a widespread, often dissimulated, political ecology that is nonetheless always present. Empirical results demonstrate that a more comprehensive handling of the political ecology of the urban is crucial in order to halt the sources of marginalisation and ecological degradation
Dyons in N=4 Supersymmetric Theories and Three-Pronged Strings
We construct and explore BPS states that preserve 1/4 of supersymmetry in N=4
Yang-Mills theories. Such states are also realized as three-pronged strings
ending on D3-branes. We correct the electric part of the BPS equation and
relate its solutions to the unbroken abelian gauge group generators. Generic
1/4-BPS solitons are not spherically symmetric, but consist of two or more
dyonic components held apart by a delicate balance between static
electromagnetic force and scalar Higgs force. The instability previously found
in three-pronged string configurations is due to excessive repulsion by one of
these static forces. We also present an alternate construction of these 1/4-BPS
states from quantum excitations around a magnetic monopole, and build up the
supermultiplet for arbitrary (quantized) electric charge. The degeneracy and
the highest spin of the supermultiplet increase linearly with a relative
electric charge. We conclude with comments.Comment: 33 pages, two figures, LaTex, a footnote added, the figure caption of
Fig.2 expanded, one more referenc
Desorption of CO and O2 interstellar ice analogs
Solid O2 has been proposed as a possible reservoir for oxygen in dense clouds
through freeze-out processes. The aim of this work is to characterize
quantitatively the physical processes that are involved in the desorption
kinetics of CO-O2 ices by interpreting laboratory temperature programmed
desorption (TPD) data. This information is used to simulate the behavior of
CO-O2 ices under astrophysical conditions. The TPD spectra have been recorded
under ultra high vacuum conditions for pure, layered and mixed morphologies for
different thicknesses, temperatures and mixing ratios. An empirical kinetic
model is used to interpret the results and to provide input parameters for
astrophysical models. Binding energies are determined for different ice
morphologies. Independent of the ice morphology, the desorption of O2 is found
to follow 0th-order kinetics. Binding energies and temperature-dependent
sticking probabilities for CO-CO, O2-O2 and CO-O2 are determined. O2 is
slightly less volatile than CO, with binding energies of 912+-15 versus 858+-15
K for pure ices. In mixed and layered ices, CO does not co-desorb with O2 but
its binding energies are slightly increased compared with pure ice whereas
those for O2 are slightly decreased. Lower limits to the sticking probabilities
of CO and O2 are 0.9 and 0.85, respectively, at temperatures below 20K. The
balance between accretion and desorption is studied for O2 and CO in
astrophysically relevant scenarios. Only minor differences are found between
the two species, i.e., both desorb between 16 and 18K in typical environments
around young stars. Thus, clouds with significant abundances of gaseous CO are
unlikely to have large amounts of solid O2.Comment: 8 pages + 2 pages online material, 8 figures (1 online), accepted by
A&
Have news reports on suicide and attempted suicide during the COVID-19 pandemic adhered to guidance on safer reporting? A UK-wide content analysis study
Background: Associations between sensational news coverage of suicide and increases in suicidal behaviour have been well documented. Amidst growing concern over the impact of the COVID-19 pandemic on suicide rates, it is especially important that news coverage adheres to recommended standards.
Methods: We analysed the quality and content of print and online UK news reports of possible COVID-19 related suicides and suicide attempts in the first four months of the pandemic (N=285).
Results: Most reports made explicit links between suicidal behaviour and the COVID-19 pandemic in the headline (65.5%), based on statements by family, friends or acquaintances of the deceased (60%). The impact of the pandemic on suicidal behaviour was most often attributed to feelings of isolation (27.4%), poor mental health (14.7%) and entrapment due to government-imposed restrictions (14.4%). Although rarely of poor overall quality, reporting was biased towards young people, frontline staff and relatively unusual suicides and, to varying degrees, failed to meet recommended standards (e.g. 41.1% did not signpost readers to sources of support).
Limitations: This analysis cannot account for the impact of reporting on suicide.
Conclusions: Careful attention must be paid to the quality and content of reports, especially as longer-term consequences of the pandemic develop
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