1,312 research outputs found
Superpixel lattices
Superpixels are small image segments that are used in popular approaches to object
detection and recognition problems. The superpixel approach is motivated by the observation
that pixels within small image segments can usually be attributed the same
label. This allows a superpixel representation to produce discriminative features based
on data dependent regions of support. The reduced set of image primitives produced
by superpixels can also be exploited to improve the efficiency of subsequent processing
steps. However, it is common for the superpixel representation to have a different graph
structure from the original pixel representation of the image.
The first part of the thesis argues that a number of desirable properties of the
pixel representation should be maintained by superpixels and that this is not possible
with existing methods. We propose a new representation, the superpixel lattice, and
demonstrate its advantages.
The second part of the thesis investigates incorporating a priori information into
superpixel segmentations. We learn a probabilistic model that describes the spatial
density of object boundaries in the image. We demonstrate our approach using road
scene data and show that our algorithm successfully exploits the spatial distribution of
object boundaries to improve the superpixel segmentation.
The third part of the thesis presents a globally optimal solution to our superpixel
lattice problem in either the horizontal or vertical direction. The solution makes use of
a Markov Random Field formulation where the label field is guaranteed to be a set of
ordered layers. We introduce an iterative algorithm that uses this framework to learn
colour distributions across an image in an unsupervised manner.
We conclude that our approach achieves comparable or better performance than
competing methods and that it confers several additional advantages
Edge Currents in Non-commutative Chern-Simons Theory from a New Matrix Model
This paper discusses the formulation of the non-commutative Chern-Simons (CS)
theory where the spatial slice, an infinite strip, is a manifold with
boundaries. As standard star products are not correct for such manifolds, the
standard non-commutative CS theory is not also appropriate here. Instead we
formulate a new finite-dimensional matrix CS model as an approximation to the
CS theory on the strip. A work which has points of contact with ours is due to
Lizzi, Vitale and Zampini where the authors obtain a description for the fuzzy
disc. The gauge fields in our approach are operators supported on a subspace of
finite dimension N+\eta of the Hilbert space of eigenstates of a simple
harmonic oscillator with N, \eta \in Z^+ and N \neq 0. This oscillator is
associated with the underlying Moyal plane. The resultant matrix CS theory has
a fuzzy edge. It becomes the required sharp edge when N and \eta goes to
infinity in a suitable sense. The non-commutative CS theory on the strip is
defined by this limiting procedure. After performing the canonical constraint
analysis of the matrix theory, we find that there are edge observables in the
theory generating a Lie algebra with properties similar to that of a
non-abelian Kac-Moody algebra. Our study shows that there are (\eta+1)^2
abelian charges (observables) given by the matrix elements (\cal A_i)_{N-1 N-1}
and (\cal A_i)_{nm} (where n or m \geq N) of the gauge fields, that obey
certain standard canonical commutation relations. In addition, the theory
contains three unique non-abelian charges, localized near the N^th level. We
show that all non-abelian edge observables except these three can be
constructed from the abelian charges above. Using the results of this analysis
we discuss the large N and \eta limit.Comment: LaTeX, 16 pages and 2 figures. Comments added in sections 4 and 5. A
minor error corrected in section 4. Figures replaced for clarity. Typos
correcte
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Attitudinal Determinants of diet and lifestyle among African and Caribbean women living in the UK : study design and rationale
The aim of this article is to describe the rationale and design of a cross-sectional study that investigated the influence of attitudinal factors on diet and lifestyle of African and Caribbean women living in the UK. The results of the study will be presented elsewhere. African and Caribbean women are at high risk of obesity which exacerbates health inequalities. In the UK, little work has been carried out to better understand attitudinal factors that contribute towards obesity, lifestyle and health practice amongst this group.
Methods:
The study applied a comprehensive questionnaire to capture socio-demographic data and explore general attitudes towards diet and lifestyle of African and Caribbean women. Dietary data were collected using triple-pass 24-hour recalls. In addition, all participants had anthropometric measures, blood pressure and biochemical indices assessed using standardised methods.
Discussion:
Potential strengths and limitations of the current study design, exploring health, diet, and lifestyle habits and the contextual influence on these practices among African and Caribbean in the UK are discussed. Findings from this study will contribute to the understanding of food and health practices, the role of socio-cultural factors and potential barriers and facilitators to the adoption of a healthy lifestyle, which could reduce the risk of cardiovascular disease, obesity, and type 2 diabetes, all of which have increased prevalence in these communities
The Fuzzy Disc
We introduce a finite dimensional matrix model approximation to the algebra
of functions on a disc based on noncommutative geometry. The algebra is a
subalgebra of the one characterizing the noncommutative plane with a * product
and depends on two parameters N and theta. It is composed of functions which
decay exponentially outside a disc. In the limit in which the size of the
matrices goes to infinity and the noncommutativity parameter goes to zero the
disc becomes sharper. We introduce a Laplacian defined on the whole algebra and
calculate its eigenvalues. We also calculate the two--points correlation
function for a free massless theory (Green's function). In both cases the
agreement with the exact result on the disc is very good already for relatively
small matrices. This opens up the possibility for the study of field theories
on the disc with nonperturbative methods. The model contains edge states, a
fact studied in a similar matrix model independently introduced by
Balachandran, Gupta and Kurkcuoglu.Comment: 17 pages, 8 figures, references added and correcte
The Australian Charter of Employment Rights: The missing dimensions
Just prior to the 2007 General Election, a group of labour lawyers and economists, broadly sympathetic to the Labor Party, produced a Charter of Employment Rights. This article examines the Charter's proposals and its underlying framework, and suggests significant aspects of work and labour have been omitted. It contends that the Charter would have been improved if it had not retained an artificially stretched definition of workers as employees, in which the only relationship worthy of inclusion in a Charter is that between the direct employer and employee. The framework and language of the Charter convey a paternalistic approach and an outdated focus on industrial labour, while ignoring aspects of the emerging global system of work linked to the concept of occupation
Deformed Traces and Covariant Quantum Algebras for Quantum Groups and
The q-deformed traces and orbits for the two parametric quantum groups
and are defined. They are subsequently used in the
construction of -orbit invariants for these groups. General
-(super)oscillator commutation relations are obtained which remain
invariant under the coactions of groups and . The
covariant deformed algebra is deduced in terms of the bilinears of
bosonic -oscillators which turns out to be a central extension of the
Witten-type deformation of algebra. In the case of the supergroup
, the corresponding covariant algebras contain
supersymmetric quantum mechanical subalgebras.Comment: LaTeX, 11 pages, a note and a reference added, relevant to
hep-th/030912
Nutritional factors and cardiovascular disease risk in Black African and Black Caribbean women: a cross-sectional study
People of Black African (BA) and Caribbean (BC) heritage form the third largest ethnic group in England and Wales. Evidence shows they experience higher rates of overweight/obesity, stroke and type 2 diabetes compared to the general population but lower risk of heart disease, which may be explained by the favourable lipid profile they exhibit (2,3). There are limited UK studies on their dietary habits and health. The aim of the current study was to assess nutritional intake and cardiovascular disease (CVD) risk factors in UK BA and BC women.
A convenience sample of self-ascribed BA and BC women, aged 19-64 years, were recruited (n = 44) from the ATTITUdinal DEterminants of diet and lifestyle (ATTITUDE) study. Cholesterol was measured using a portable CardioChek Blood Analyser, blood pressure using a digital blood pressure monitor and dietary intake via triple pass 24hr recall. Ethical approval was obtained from London Metropolitan University, King’s College London and Westminster University. Percentage energy, total fat, saturated fat, carbohydrate, and fibre and salt intake were calculated and under-reporting was assessed using the Goldberg equation. A sensitivity analysis conducted on nutrient intakes with under-reporters removed.
Nutritional intake and CVD risk factors are shown in Table 1. Sixty three percent of participants were overweight or obese. Analysis of the dietary data revealed higher intakes salt, free sugars, fat and saturated fat than recommendations and lower intake of carbohydrate. Sensitivity analysis was conducted to investigate the impact of under-reporting (n = 22). Reported data remained unchanged except for fibre intake, which was lower in the under-reporters (14.9g compared to 21.0g) (P = 0.004). Blood lipid profiles and blood pressure data were within recommendations. In conclusion, the anthropometric and certain dietary measures would indicate increased risk for developing CVD in BA and BC women, however, blood lipid profile and blood pressure measures were within healthy ranges
Uptake of smoking cessation aids by smokers with a mental illness
Psychiatric inpatient settings represent an opportunity to initiate the provision of tobacco cessation care to smokers with a mental illness. This study describes the use of evidence-based smoking cessation aids proactively and universally offered to a population of psychiatric inpatients upon discharge, and explores factors associated with their uptake. Data derived from the conduct of a randomised controlled trial were analysed in terms of the proportion of participants (N = 378) that utilised cessation aids including project delivered telephone smoking cessation counselling and nicotine replacement therapy (NRT), and Quitline support. Factors associated with uptake of cessation aids were explored using multivariable logistic regression analyses. A large proportion of smokers utilised project delivered cessation counselling calls (89 %) and NRT (79 %), while 11 % used the Quitline. The majority accepted more than seven project delivered telephone cessation counselling calls (52 %), and reported NRT use during more than half of their accepted calls (70 %). Older age, higher nicotine dependence, irregular smoking and seeing oneself as a non-smoker were associated with uptake of behavioural cessation aids. Higher nicotine dependence was similarly associated with use of pharmacological aids, as was NRT use whilst an inpatient. Most smokers with a mental illness took up a proactive offer of aids to support their stopping smoking. Consideration by service providers of factors associated with uptake may increase further the proportion of such smokers who use evidence-based cessation aids and consequently quit smoking successfully
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