2,653 research outputs found
Resource variation in colorectal surgery; a national centre-level analysis.
BACKGROUND: Delivery of quality colorectal surgery requires adequate resources. We set out to assess the relationship between resources and outcomes in English colorectal units. METHODS: Data was extracted from the ACPGBI resource questionnaire to profile resources. This was correlated with Hospital Episode Statistics (HES) outcome data including 90-day mortality and readmissions. Patient satisfaction measures were extracted from the Cancer Experience Patient Survey (CEPS) and compared at unit level. Centres were divided by workload into low, middle, and top tertile. RESULTS: Completed questionnaires were received from 75 centres in England. Service resources were similar between low and top tertiles in access to CEPOD theatre, level 2 or 3 beds per 250,000 population or likelihood of having a dedicated colorectal ward. There was no difference in staffing levels per 250,000 unit of population. Each 10% increase in the proportion of cases attempted laparoscopically, was associated with reduced 90-day unplanned readmission (RR 0.94, 95% CI 0.91 to 0.97, p<0.001). The presence of a dedicated colorectal ward (RR 0.85, 95% CI 0.73 to 0.99, p =0.040) was also associated with a significant reduction in unplanned readmissions. There was no association between staffing or service factors and patient satisfaction. DISCUSSION AND CONCLUSIONS: Resource levels do not vary based on unit of population. There is benefit associated with increased use of laparoscopy and a dedicated surgical ward. Alternative measures to assess the relationship between resources and outcome, such as failure to rescue, should be explored in UK practice. This article is protected by copyright. All rights reserved
Taking a Leap of Faith: Redefining Teaching and Learning in Higher Education Through Project-Based Learning
This study examines two aspects of teaching with a project-based learning (PBL) model in higher education settings: faculty definitions of PBL and faculty PBL practices, as evidenced by their self-described successes and challenges in implementation. Faculty participants took “a leap of faith” in their teaching practices to redefine what it means to teach and learn using PBL as an instructional methodology. The findings provide insight into how faculty conceptualization of PBL drives implementation; how the PBL approach challenges college-level teachers; and how instructors’ perceptions of their own role in the PBL process impacts how they implement PBL
Entropy/IP: Uncovering Structure in IPv6 Addresses
In this paper, we introduce Entropy/IP: a system that discovers Internet
address structure based on analyses of a subset of IPv6 addresses known to be
active, i.e., training data, gleaned by readily available passive and active
means. The system is completely automated and employs a combination of
information-theoretic and machine learning techniques to probabilistically
model IPv6 addresses. We present results showing that our system is effective
in exposing structural characteristics of portions of the IPv6 Internet address
space populated by active client, service, and router addresses.
In addition to visualizing the address structure for exploration, the system
uses its models to generate candidate target addresses for scanning. For each
of 15 evaluated datasets, we train on 1K addresses and generate 1M candidates
for scanning. We achieve some success in 14 datasets, finding up to 40% of the
generated addresses to be active. In 11 of these datasets, we find active
network identifiers (e.g., /64 prefixes or `subnets') not seen in training.
Thus, we provide the first evidence that it is practical to discover subnets
and hosts by scanning probabilistically selected areas of the IPv6 address
space not known to contain active hosts a priori.Comment: Paper presented at the ACM IMC 2016 in Santa Monica, USA
(https://dl.acm.org/citation.cfm?id=2987445). Live Demo site available at
http://www.entropy-ip.com
Enumerative and asymptotic analysis of a moduli space
We focus on combinatorial aspects of the Hilbert series of the cohomology
ring of the moduli space of stable pointed curves of genus zero. We show its
graded Hilbert series satisfies an integral operator identity. This is used to
give asymptotic behavior, and in some cases, exact values, of the coefficients
themselves. We then study the total dimension, that is, the sum of the
coefficients of the Hilbert series. Its asymptotic behavior involves the
Lambert W function, which has applications to classical tree enumeration,
signal processing and fluid mechanics.Comment: 14 page
The current status of clinical trials in emergency gastrointestinal surgery. A systematic analysis of contemporary clinical trials
BACKGROUND: Emergency gastrointestinal surgery (EGS) conditions represent a significant healthcare burden globally requiring emergency operations that are associated with mortality rates as high as 80%. EGS is currently focussed on quality improvement and internal audits, which occurs at a national or local level. An appreciation of what EGS trials are being conducted is important to reduce research wastage and develop coordinated research strategies in surgery. The primary aim of this study was to identify and quantify recent and active trials in emergency gastrointestinal surgery. The secondary aim was to identify conditions of interest, and which aspects of care were being modified. METHODS: A systematic search of WHO, UK, US, Australian and Canadian trials databases was undertaken using broad terms to identify studies addressing emergency abdominal surgery and specific high-risk diagnoses. Studies registered between 2013-2018 were eligible for inclusion. Data on study topic, design, and funding body were collected. Interventions were classified into 'peri-operative', 'procedural', 'post-operative', 'non-surgical' and 'other' categories. RESULTS: Searches identified 5603 registered trials. After removal of duplicates, 4492 studies remained and 42 were eligible for inclusion. Almost 50% of trials were located in Europe and 17% (n=7) in the USA. The most common condition addressed was acute appendicitis (n=11), with the most common intervention being procedure based (n=23). Hospital based funding was the most common funder (n=30). CONCLUSION: There is large disparity in the number of surgical trials in emergency surgery, which are primarily focussed on high-volume conditions. More research is needed into high-mortality conditions. EVIDENCE LEVEL: 1a (oxford)
Instability of dilute granular flow on rough slope
We study numerically the stability of granular flow on a rough slope in
collisional flow regime in the two-dimension. We examine the density dependence
of the flowing behavior in low density region, and demonstrate that the
particle collisions stabilize the flow above a certain density in the parameter
region where a single particle shows an accelerated behavior. Within this
parameter regime, however, the uniform flow is only metastable and is shown to
be unstable against clustering when the particle density is not high enough.Comment: 4 pages, 6 figures, submitted to J. Phys. Soc. Jpn.; Fig. 2 replaced;
references added; comments added; misprints correcte
Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
AIMS. We present abundance analysis based on high resolution spectra of 105
isolated red giant branch (RGB) stars in the Galactic Globular Cluster NGC 6121
(M4). Our aim is to study its star population in the context of the
multi-population phenomenon recently discovered to affect some Globular
Clusters. METHODS. The data have been collected with FLAMES+UVES, at the
ESO/VLT@UT2 telescope. Analysis was performed under LTE approximation for the
following elements: O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Ba, and NLTE
corrections were applied to Na and Mg. Spectroscopic data were coupled with
high-precision wide-field UBVI photometry from [email protected] telescope and
infrared JHK photometry from 2MASS. RESULTS: We derived an average (internal error), and an enhancement of dex (internal error). We confirm the presence of an
extended Na-O anticorrelation, and find two distinct groups of stars with
significantly different Na and O content. We find no evidence of a Mg-Al
anticorrelation. By coupling our results with previous studies on the CN band
strength, we find that the CN strong stars have higher Na and Al content and
are more O depleted than the CN weak ones. The two groups of Na-rich, CN-strong
and Na-poor, CN-weak stars populate two different regions along the RGB. In the
vs. color magnitude diagram the RGB spread is present rom
the base of the RGB to the RGB-tip. Apparently, both spectroscopic and
photometric results imply the presence of two stellar populations in M4. We
briefly discuss the possible origin of these populations.Comment: 21 pages, 16 figures, accepted for publication in Astronomy and
Astrophysic
Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b
We present the transmission spectrum of HAT-P-12b through a joint analysis of
data obtained from the Hubble Space Telescope Space Telescope Imaging
Spectrograph (STIS) and Wide Field Camera 3 (WFC3) and Spitzer, covering the
wavelength range 0.3-5.0 m. We detect a muted water vapor absorption
feature at 1.4 m attenuated by clouds, as well as a Rayleigh scattering
slope in the optical indicative of small particles. We interpret the
transmission spectrum using both the state-of-the-art atmospheric retrieval
code SCARLET and the aerosol microphysics model CARMA. These models indicate
that the atmosphere of HAT-P-12b is consistent with a broad range of
metallicities between several tens to a few hundred times solar, a roughly
solar C/O ratio, and moderately efficient vertical mixing. Cloud models that
include condensate clouds do not readily generate the sub-micron particles
necessary to reproduce the observed Rayleigh scattering slope, while models
that incorporate photochemical hazes composed of soot or tholins are able to
match the full transmission spectrum. From a complementary analysis of
secondary eclipses by Spitzer, we obtain measured depths of
and at 3.6 and 4.5 m, respectively, which are
consistent with a blackbody temperature of K and indicate
efficient day-night heat recirculation. HAT-P-12b joins the growing number of
well-characterized warm planets that underscore the importance of clouds and
hazes in our understanding of exoplanet atmospheres.Comment: 25 pages, 19 figures, accepted for publication in AJ, updated with
proof correction
Accounting for Calibration Uncertainties in X-ray Analysis: Effective Areas in Spectral Fitting
While considerable advance has been made to account for statistical
uncertainties in astronomical analyses, systematic instrumental uncertainties
have been generally ignored. This can be crucial to a proper interpretation of
analysis results because instrumental calibration uncertainty is a form of
systematic uncertainty. Ignoring it can underestimate error bars and introduce
bias into the fitted values of model parameters. Accounting for such
uncertainties currently requires extensive case-specific simulations if using
existing analysis packages. Here we present general statistical methods that
incorporate calibration uncertainties into spectral analysis of high-energy
data. We first present a method based on multiple imputation that can be
applied with any fitting method, but is necessarily approximate. We then
describe a more exact Bayesian approach that works in conjunction with a Markov
chain Monte Carlo based fitting. We explore methods for improving computational
efficiency, and in particular detail a method of summarizing calibration
uncertainties with a principal component analysis of samples of plausible
calibration files. This method is implemented using recently codified Chandra
effective area uncertainties for low-resolution spectral analysis and is
verified using both simulated and actual Chandra data. Our procedure for
incorporating effective area uncertainty is easily generalized to other types
of calibration uncertainties.Comment: 61 pages double spaced, 8 figures, accepted for publication in Ap
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