1,951 research outputs found
String Branchings on Complex Tori and Algebraic Representations of Generalized Krichever-Novikov Algebras
The propagation differential for bosonic strings on a complex torus with
three symmetric punctures is investigated. We study deformation aspects between
two point and three point differentials as well as the behaviour of the
corresponding Krichever-Novikov algebras. The structure constants are
calculated and from this we derive a central extension of the Krichever-Novikov
algebras by means of b-c systems. The defining cocycle for this central
extension deforms to the well known Virasoro cocycle for certain kinds of
degenerations of the torus.
AMS subject classification (1991): 17B66, 17B90, 14H52, 30F30, 81T40Comment: 11 pages, amste
Prevalence and impact of chronic widespread pain in the Bangladeshi and White populations of Tower Hamlets, East London
The prevalence and impact of chronic pain differ between ethnic groups. We report a study of the comparative prevalence and impact of chronic pain in Bangladeshi, British Bangladeshi and White British/Irish people. We posted a short questionnaire to a random sample of 4,480 patients registered with 16 general practices in the London Borough of Tower Hamlets and conducted a longer questionnaire with patients in the waiting areas at those practices. We distinguished between Bangladeshi participants who were born in the UK or had arrived in the UK at the age of 14 or under (British Bangladeshi) and those who arrived in UK at the age of over 14 (Bangladeshi). We obtained 1,223/4,480 (27 %) responses to the short survey and 600/637 (94 %) to the long survey. From the former, the prevalence of chronic pain in the White, British Bangladeshi and Bangladeshi groups was 55, 54 and 72 %, respectively. The corresponding figures from the long survey were 49, 45 and 70 %. Chronic widespread pain was commoner in the Bangladeshi (16 %) than in the White (10 %) or British Bangladeshi (9 %) groups. People with chronic pain experienced poorer quality of life (odds ratio for scoring best possible health vs. good health (or good vs. poor health) 5.6 (95 % confidence interval 3.4 to 9.8)), but we found no evidence of differences between ethnic groups in the impact of chronic pain on the quality of life. Chronic pain is commoner and, of greater severity, in Bangladeshis than in Whites. On most measures in this study, British Bangladeshis resembled the Whites more than the Bangladeshis
Contact Representations of Graphs in 3D
We study contact representations of graphs in which vertices are represented
by axis-aligned polyhedra in 3D and edges are realized by non-zero area common
boundaries between corresponding polyhedra. We show that for every 3-connected
planar graph, there exists a simultaneous representation of the graph and its
dual with 3D boxes. We give a linear-time algorithm for constructing such a
representation. This result extends the existing primal-dual contact
representations of planar graphs in 2D using circles and triangles. While
contact graphs in 2D directly correspond to planar graphs, we next study
representations of non-planar graphs in 3D. In particular we consider
representations of optimal 1-planar graphs. A graph is 1-planar if there exists
a drawing in the plane where each edge is crossed at most once, and an optimal
n-vertex 1-planar graph has the maximum (4n - 8) number of edges. We describe a
linear-time algorithm for representing optimal 1-planar graphs without
separating 4-cycles with 3D boxes. However, not every optimal 1-planar graph
admits a representation with boxes. Hence, we consider contact representations
with the next simplest axis-aligned 3D object, L-shaped polyhedra. We provide a
quadratic-time algorithm for representing optimal 1-planar graph with L-shaped
polyhedra
Bell Inequalities with Auxiliary Communication
What is the communication cost of simulating the correlations produced by
quantum theory? We generalize Bell inequalities to the setting of local
realistic theories augmented by a fixed amount of classical communication.
Suppose two parties choose one of M two-outcome measurements and exchange 1 bit
of information. We present the complete set of inequalities for M = 2, and the
complete set of inequalities for the joint correlation observable for M = 3. We
find that correlations produced by quantum theory satisfy both of these sets of
inequalities. One bit of communication is therefore sufficient to simulate
quantum correlations in both of these scenarios.Comment: 5 page
Effect of increasing fruit and vegetable intake by dietary intervention on nutritional biomarkers and attitudes to dietary change : a randomised trial
This work was funded by The Scottish Government Rural and Environmental Science and Analytical Sciences Division (RESAS) and supported by the Rank Prize Funds.Peer reviewedPublisher PD
Symptoms associated with victimization in patients with schizophrenia and related disorders
Background: Patients with psychoses have an increased risk of becoming victims of violence. Previous studies have suggested that higher symptom levels are associated with a raised risk of becoming a victim of physical violence. There has been, however, no evidence on the type of symptoms that are linked with an increased risk of recent victimization. Methods: Data was taken from two studies on involuntarily admitted patients, one national study in England and an international one in six other European countries. In the week following admission, trained interviewers asked patients whether they had been victims of physical violence in the year prior to admission, and assessed symptoms on the Brief Psychiatric Rating Scale (BPRS). Only patients with a diagnosis of schizophrenia or related disorders (ICD-10 F20–29) were included in the analysis which was conducted separately for the two samples. Symptom levels assessed on the BPRS subscales were tested as predictors of victimization. Univariable and multivariable logistic regression models were fitted to estimate adjusted odds ratios. Results: Data from 383 patients in the English sample and 543 patients in the European sample was analysed. Rates of victimization were 37.8% and 28.0% respectively. In multivariable models, the BPRS manic subscale was significantly associated with victimization in both samples. Conclusions: Higher levels of manic symptoms indicate a raised risk of being a victim of violence in involuntary patients with schizophrenia and related disorders. This might be explained by higher activity levels, impaired judgement or poorer self-control in patients with manic symptoms. Such symptoms should be specifically considered in risk assessments
Global Examination of the C+C Reaction Data at Low and Intermediate Energies
We examine the C+C elastic scattering over a wide energy range
from 32.0 to 70.7 MeV in the laboratory system within the framework of the
Optical model and the Coupled-Channels formalism. The C+C system
has been extensively studied within and over this energy range in the past.
These efforts have been futile in determining the shape of the nuclear
potential in the low energy region and in describing the individual angular
distributions, single-angle 50 to 90 excitation functions and
reaction cross-section data simultaneously. In order to address these problems
systematically, we propose a potential that belongs to a family other than the
one used to describe higher energy experimental data and show that it is
possible to use it over this wide energy range. This potential also predicts
the resonances at correct energies with reasonable widths.Comment: 30 pages with 13 eps figues and 3 tables, LaTeX-Revtex
The development of path integration: combining estimations of distance and heading
Efficient daily navigation is underpinned by path integration, the mechanism by which we use self-movement information to update our position in space. This process is well-understood in adulthood, but there has been relatively little study of path integration in childhood, leading to an underrepresentation in accounts of navigational development. Previous research has shown that calculation of distance and heading both tend to be less accurate in children as they are in adults, although there have been no studies of the combined calculation of distance and heading that typifies naturalistic path integration. In the present study 5-year-olds and 7-year-olds took part in a triangle-completion task, where they were required to return to the startpoint of a multi-element path using only idiothetic information. Performance was compared to a sample of adult participants, who were found to be more accurate than children on measures of landing error, heading error, and distance error. 7-year-olds were significantly more accurate than 5-year-olds on measures of landing error and heading error, although the difference between groups was much smaller for distance error. All measures were reliably correlated with age, demonstrating a clear development of path integration abilities within the age range tested. Taken together, these data make a strong case for the inclusion of path integration within developmental models of spatial navigational processing
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