7,517 research outputs found
Learning curves and the influence of procedural volume for the treatment of dysplastic Barrett's esophagus
BACKGROUND AND AIMS: Endoscopic resections (ER) and radiofrequency ablation (RFA) are the established treatments for Barrett's-associated dysplasia and early esophageal neoplasia. The UK RFA Registry collects patient outcomes from 24 centers in the United Kingdom and Ireland treating patients. Learning curves for treatment of Barrett's dysplasia and the impact of center caseload on patient outcomes is still unknown. METHODS: We examined outcomes of 678 patients treated with RFA in the UK Registry using risk-adjusted CUSUM plots to identify change points in complete resolution of intestinal metaplasia (CR-IM) and complete resolution of dysplasia (CR-D) outcomes. We compared outcomes between those treated at high- (>100 enrolled patients), medium- (51-100) and low- (<50) volume centers. RESULTS: There was no association between center volume and CR-IM and CR-D rates, but there were lower recurrence rates in high-volume versus low-volume centers (Log Rank p=0.001).There was a significant change-point for outcomes at 12 cases for CR-D (reduction from 24.5% to 10.4%; P<0.001) and at 18 cases for CR-IM (30.7% to 18.6%; P<0.001) from RA-CUSUM curve analysis. CONCLUSION: Our data suggest that 18 supervised cases of endoscopic ablation may be required before competency in endoscopic treatment of Barrett's dysplasia can be achieved. The difference in outcomes between a high-volume and low-volume center does not support further centralization of services to only high-volume centers
Online unit clustering in higher dimensions
We revisit the online Unit Clustering and Unit Covering problems in higher
dimensions: Given a set of points in a metric space, that arrive one by
one, Unit Clustering asks to partition the points into the minimum number of
clusters (subsets) of diameter at most one; while Unit Covering asks to cover
all points by the minimum number of balls of unit radius. In this paper, we
work in using the norm.
We show that the competitive ratio of any online algorithm (deterministic or
randomized) for Unit Clustering must depend on the dimension . We also give
a randomized online algorithm with competitive ratio for Unit
Clustering}of integer points (i.e., points in , , under norm). We show that the competitive ratio of
any deterministic online algorithm for Unit Covering is at least . This
ratio is the best possible, as it can be attained by a simple deterministic
algorithm that assigns points to a predefined set of unit cubes. We complement
these results with some additional lower bounds for related problems in higher
dimensions.Comment: 15 pages, 4 figures. A preliminary version appeared in the
Proceedings of the 15th Workshop on Approximation and Online Algorithms (WAOA
2017
Continuous Experimentation for Automotive Software on the Example of a Heavy Commercial Vehicle in Daily Operation
As the automotive industry focuses its attention more and more towards the
software functionality of vehicles, techniques to deliver new software value at
a fast pace are needed. Continuous Experimentation, a practice coming from the
web-based systems world, is one of such techniques. It enables researchers and
developers to use real-world data to verify their hypothesis and steer the
software evolution based on performances and user preferences, reducing the
reliance on simulations and guesswork. Several challenges prevent the verbatim
adoption of this practice on automotive cyber-physical systems, e.g., safety
concerns and limitations from computational resources; nonetheless, the
automotive field is starting to take interest in this technique. This work aims
at demonstrating and evaluating a prototypical Continuous Experimentation
infrastructure, implemented on a distributed computational system housed in a
commercial truck tractor that is used in daily operations by a logistic company
on public roads. The system comprises computing units and sensors, and software
deployment and data retrieval are only possible remotely via a mobile data
connection due to the commercial interests of the logistics company. This study
shows that the proposed experimentation process resulted in the development
team being able to base software development choices on the real-world data
collected during the experimental procedure. Additionally, a set of previously
identified design criteria to enable Continuous Experimentation on automotive
systems was discussed and their validity confirmed in the light of the
presented work.Comment: Paper accepted to the 14th European Conference on Software
Architecture (ECSA 2020). 16 pages, 5 figure
A spin triplet supercurrent through the half-metallic ferromagnet CrO2
In general, conventional superconductivity should not occur in a ferromagnet,
though it has been seen in iron under pressure. Moreover, theory predicts that
the current is always carried by pairs of electrons in a spin singlet state, so
conventional superconductivity decays very rapidly when in contact with a
ferromagnet, which normally prohibits the existence of singlet pairs. It has
been predicted that this rapid spatial decay would not occur when spin triplet
superconductivity could be induced in the ferromagnet. Here we report a
Josephson supercurrent through the strong ferromagnet CrO2, from which we infer
that it is a spin triplet supercurrent. Our experimental setup is different
from those envisaged in the earlier predictions, but we conclude that the
underlying physical explanation for our result is a conversion from spin
singlet to spin triplets at the interface. The supercurrent can be switched
with the direction of the magnetization, analogous to spin valve transistors,
and therefore could enable magnetization-controlled Josephson junctions.Comment: 14 pages, including 3 figure
Computing a maximum clique in geometric superclasses of disk graphs
In the 90's Clark, Colbourn and Johnson wrote a seminal paper where they
proved that maximum clique can be solved in polynomial time in unit disk
graphs. Since then, the complexity of maximum clique in intersection graphs of
d-dimensional (unit) balls has been investigated. For ball graphs, the problem
is NP-hard, as shown by Bonamy et al. (FOCS '18). They also gave an efficient
polynomial time approximation scheme (EPTAS) for disk graphs. However, the
complexity of maximum clique in this setting remains unknown. In this paper, we
show the existence of a polynomial time algorithm for a geometric superclass of
unit disk graphs. Moreover, we give partial results toward obtaining an EPTAS
for intersection graphs of convex pseudo-disks
Metabonomics and Intensive Care
This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901
The influence of maternal and infant nutrition on cardiometabolic traits: novel findings and future research directions from four Canadian birth cohort studies
A mother's nutritional choices while pregnant may have a great influence on her baby's development in the womb and during infancy. There is evidence that what a mother eats during pregnancy interacts with her genes to affect her child's susceptibility to poor health outcomes including childhood obesity, pre-diabetes, allergy and asthma. Furthermore, after what an infant eats can change his or her intestinal bacteria, which can further influence the development of these poor outcomes. In the present paper, we review the importance of birth cohorts, the formation and early findings from a multi-ethnic birth cohort alliance in Canada and summarise our future research directions for this birth cohort alliance. We summarise a method for harmonising collection and analysis of self-reported dietary data across multiple cohorts and provide examples of how this birth cohort alliance has contributed to our understanding of gestational diabetes risk; ethnic and diet-influences differences in the healthy infant microbiome; and the interplay between diet, ethnicity and birth weight. Ongoing work in this birth cohort alliance will focus on the use of metabolomic profiling to measure dietary intake, discovery of unique diet–gene and diet–epigenome interactions, and qualitative interviews with families of children at risk of metabolic syndrome. Our findings to-date and future areas of research will advance the evidence base that informs dietary guidelines in pregnancy, infancy and childhood, and will be relevant to diverse and high-risk populations of Canada and other high-income countries
Automatic eduction and statistical analysis of coherent structures in the wall region of a confine plane
This paper describes a vortex detection algorithm used to expose and statistically characterize the
coherent flow patterns observable in the velocity vector fields measured by Particle Image
Velocimetry (PIV) in the impingement region of air curtains. The philosophy and the architecture of
this algorithm are presented. Its strengths and weaknesses are discussed. The results of a
parametrical analysis performed to assess the variability of the response of our algorithm to the 3
user-specified parameters in our eduction scheme are reviewed. The technique is illustrated in the
case of a plane turbulent impinging twin-jet with an opening ratio of 10. The corresponding jet
Reynolds number, based on the initial mean flow velocity U0 and the jet width e, is 14000. The
results of a statistical analysis of the size, shape, spatial distribution and energetic content of the
coherent eddy structures detected in the impingement region of this test flow are provided.
Although many questions remain open, new insights into the way these structures might form,
organize and evolve are given. Relevant results provide an original picture of the plane turbulent
impinging jet
Movies and TV Influence Tobacco Use in India: Findings from a National Survey
Background: Exposure to mass media may impact the use of tobacco, a major source of illness and death in India. The objective is to test the association of self-reported tobacco smoking and chewing with frequency of use of four types of mass media: newspapers, radio, television, and movies. Methodology/Principal Findings: We analyzed data from a sex-stratified nationally-representative cross-sectional survey of 123,768 women and 74,068 men in India. All models controlled for wealth, education, caste, occupation, urbanicity, religion, marital status, and age. In fully-adjusted models, monthly cinema attendance is associated with increased smoking among women (relative risk [RR]: 1·55; 95% confidence interval [CI]: 1·04–2·31) and men (RR: 1·17; 95% CI: 1·12–1·23) and increased tobacco chewing among men (RR: 1·15; 95% CI: 1·11–1·20). Daily television and radio use is associated with higher likelihood of tobacco chewing among men and women, while daily newspaper use is related to lower likelihood of tobacco chewing among women. Conclusion/Significance: In India, exposure to visual mass media may contribute to increased tobacco consumption in men and women, while newspaper use may suppress the use of tobacco chewing in women. Future studies should investigate the role that different types of media content and media play in influencing other health behaviors
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