6,371 research outputs found
Assessing smoking status in children, adolescents and adults: cotinine cut-points revisited
Aims To reassess saliva cotinine cut-points to discriminate smoking status. Cotinine cut-points that are in use were derived from relatively small samples of smokers and non-smokers 20 or more years ago. It is possible that optimal cut-points may have changed as prevalence and exposure to passive smoking have declined. Design Cross-sectional survey of the general population, with assessment of self-reported smoking and saliva cotinine. Participants A total of 58 791 respondents aged 4 years and older in the Health Survey for England for the years 1996-2004 who provided valid saliva cotinine specimens. Measures Saliva cotinine concentrations, demographic variables, self-reported smoking, presence or absence of smoking in the home, a composite index of social disadvantage derived from occupation, housing tenure and access to a car. Findigns A cut-point of 12 ng/ml performed best overall, with specificity of 96.9% and sensitivity of 96.7% in discriminating confirmed cigarette smokers from never regular smokers. This cut-point also identified correctly 95.8% of children aged 8-15 years smoking six or more cigarettes a week. There was evidence of substantial misreport in claimed ex-smokers, especially adolescents (specificity 72.3%) and young adults aged 16-24 years (77.5%). Optimal cut-points varied by presence (18 ng/ml) or absence (5 ng/ml) of smoking in the home, and there was a gradient from 8 ng/ml to 18 ng/ml with increasing social disadvantage. Conclusions The extent of non-smokers' exposure to other people's tobacco smoke is the principal factor driving optimal cotinine cut-points. A cut-point of 12 ng/ml can be recommended for general use across the whole age range, although different cut-points may be appropriate for population subgroups and in societies with differing levels of exposure to secondhand smoke
Generalised Space-time and Gauge Transformations
We consider the generalised space-time introduced by the author in 2003 in
the context of the non-linear realisation of the semi-direct product of E11 and
its first fundamental representation. For all the fields we propose gauge
transformations which are compatible with the underlying E11 structure. A
crucial role is played by the generalised vielbein that the generalised
space-time possess. We work out the explicit form of the gauge transformations,
at low levels, in four, five and eleven dimensions.Comment: 33 page
'The smoking toolkit study': a national study of smoking and smoking cessation in England
Background: Up-to-date data tracking of national smoking patterns and cessation-related behaviour is required to evaluate and inform tobacco control strategies. The Smoking Toolkit Study (STS) was designed for this role. This paper describes the methodology of the STS and examines as far as possible the representativeness of the samples.Methods: The STS consists of monthly, cross sectional household interviews of adults aged 16 and over in England with smokers and recent ex-smokers in each monthly wave followed up by postal questionnaires three and six months later. Between November 2006 and December 2010 the baseline survey was completed by 90,568 participants. STS demographic, prevalence and cigarette consumption estimates are compared with those from the Health Survey for England (HSE) and the General Lifestyle Survey (GLF) for 2007-2009.Results: Smoking prevalence estimates of all the surveys were similar from 2008 onwards (e. g 2008 STS = 22.0%, 95% C. I. = 21.4% to 22.6%, HSE = 21.7%, 95% C. I. = 20.9% to 22.6%, GLF = 20.8%, 95% C. I. = 19.7% to 21.9%), although there was heterogeneity in 2007 (chi-square = 50.30, p < 0.001). Some differences were observed across surveys within sociodemographic sub-groups, although largely in 2007. Cigarette consumption was virtually identical in all surveys and years.Conclusion: There is reason to believe that the STS findings (see http://www.smokinginengland.info) are generalisable to the adult population of England
Sneeze to leave: African wild dogs (Lycaon pictus) use variable quorum thresholds facilitated by sneezes in collective decisions
The Emerging Scholarly Brain
It is now a commonplace observation that human society is becoming a coherent
super-organism, and that the information infrastructure forms its emerging
brain. Perhaps, as the underlying technologies are likely to become billions of
times more powerful than those we have today, we could say that we are now
building the lizard brain for the future organism.Comment: to appear in Future Professional Communication in Astronomy-II
(FPCA-II) editors A. Heck and A. Accomazz
FSL-BM: Fuzzy Supervised Learning with Binary Meta-Feature for Classification
This paper introduces a novel real-time Fuzzy Supervised Learning with Binary
Meta-Feature (FSL-BM) for big data classification task. The study of real-time
algorithms addresses several major concerns, which are namely: accuracy, memory
consumption, and ability to stretch assumptions and time complexity. Attaining
a fast computational model providing fuzzy logic and supervised learning is one
of the main challenges in the machine learning. In this research paper, we
present FSL-BM algorithm as an efficient solution of supervised learning with
fuzzy logic processing using binary meta-feature representation using Hamming
Distance and Hash function to relax assumptions. While many studies focused on
reducing time complexity and increasing accuracy during the last decade, the
novel contribution of this proposed solution comes through integration of
Hamming Distance, Hash function, binary meta-features, binary classification to
provide real time supervised method. Hash Tables (HT) component gives a fast
access to existing indices; and therefore, the generation of new indices in a
constant time complexity, which supersedes existing fuzzy supervised algorithms
with better or comparable results. To summarize, the main contribution of this
technique for real-time Fuzzy Supervised Learning is to represent hypothesis
through binary input as meta-feature space and creating the Fuzzy Supervised
Hash table to train and validate model.Comment: FICC201
Cosmological parameters from the clustering of AGN
We attempt to put constraints on different cosmological and biasing models by
combining the recent clustering results of X-ray sources in the local () and distant universe ().Comment: 9 pages, 3 figures, to be published in the proceedings of the ''2nd
Hellenic Cosmology Workshop'', Athens 2001, eds, Manolis Plionis & Spiros
Kotsaki
Generalized Geometry and M theory
We reformulate the Hamiltonian form of bosonic eleven dimensional
supergravity in terms of an object that unifies the three-form and the metric.
For the case of four spatial dimensions, the duality group is manifest and the
metric and C-field are on an equal footing even though no dimensional reduction
is required for our results to hold. One may also describe our results using
the generalized geometry that emerges from membrane duality. The relationship
between the twisted Courant algebra and the gauge symmetries of eleven
dimensional supergravity are described in detail.Comment: 29 pages of Latex, v2 References added, typos fixed, v3 corrected
kinetic term and references adde
Double Field Theory Formulation of Heterotic Strings
We extend the recently constructed double field theory formulation of the
low-energy theory of the closed bosonic string to the heterotic string. The
action can be written in terms of a generalized metric that is a covariant
tensor under O(D,D+n), where n denotes the number of gauge vectors, and n
additional coordinates are introduced together with a covariant constraint that
locally removes these new coordinates. For the abelian subsector, the action
takes the same structural form as for the bosonic string, but based on the
enlarged generalized metric, thereby featuring a global O(D,D+n) symmetry.
After turning on non-abelian gauge couplings, this global symmetry is broken,
but the action can still be written in a fully O(D,D+n) covariant fashion, in
analogy to similar constructions in gauged supergravities.Comment: 28 pages, v2: minor changes, version published in JHE
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