4,914 research outputs found
Climate change and variability, energy and disaster management: produced risks without produced solutions: rethinking the approach
Accelerated climate change and increasing climate variability is the single largest threat to the international goals of sustainable development, the Millennium Development Goals (MDGs) and disaster risk reduction. Global discourses recognise the need for effective and sustainable responses tso produced climate risks. The risk types likely to occur are known, but only in broad terms - their scale, severity, longevity and frequency are not known. The challenge for policymakers is developing an effective framework within which sustainable responses can be formulated. To address the problems of produced risks a comprehensive approach to risk management is necessary. The mechanisms within the climate change, sustainable development and disaster risk reduction discourses are not sufficiently effective or integrated to respond to this challenge. Fundamental reform to current modes of risk reduction is needed, but this can only be achieved through a shift in the dominant perspective on formulating sustainable responses. This requires a shift to an enabling policy framework that encourages bottom-up resilient responses. Resilience is argued as a tool for policy development that can enhance adaptive capacity to current climate risks and shape energy policy to respond to mitigate future climate risks
Testing isomorphism of graded algebras
We present a new algorithm to decide isomorphism between finite graded
algebras. For a broad class of nilpotent Lie algebras, we demonstrate that it
runs in time polynomial in the order of the input algebras. We introduce
heuristics that often dramatically improve the performance of the algorithm and
report on an implementation in Magma
Agreement between mothers and children with malocclusion in rating children's oral health-related quality of life
Introduction: The aim of this study was to compare the assessment of oral health-related quality of life (OH-QoL) between children with malocclusion and their mothers, by using responses to the child perceptions questionnaire and the parental-caregivers perceptions questionnaire. Methods: The study was conducted in 90 children, aged 11 to 14 years, with a malocclusion grade of 4 or 5 according to the index of orthodontic treatement need dental health component. The children and their mothers completed the questionnaires independently. Results: The mean ratings were similar for total scores (children, 20.4; mothers, 20.1), oral symptoms (children, 5.2; mothers, 4.7), and social well-being (children, 4.3; mothers, 4.8). However, the mothers group had a lower mean score for functional limitations (children, 5.3; mothers, 3.6) and a higher mean score for emotional well-being (children, 5.6; mothers, 7.1). The correlations between children's and mothers' responses ranged from rs = 0.545 for total score and emotional well-being to rs = 0.357 for functional limitations. There were good correlations between their responses to global (rs = 0.466) and life overall (rs = 0.427) questions, but poor correlations between the 2 questions, suggesting that these concepts were considered differently. Conclusions: Maternal opinions were similar to those of their children for the overall impact on OH-QoL of malocclusion, but mothers were more dissatisfied with the appearance of their children's teeth and overestimated the emotional impact of malocclusion. It would be useful to develop a specific measure to assess OH-QoL in children with malocclusion. (Am J Orthod Dentofacial Orthop 2010;137:631-8
Recognising the small Ree groups in their natural representations
We present Las Vegas algorithms for constructive recognition and constructive
membership testing of the Ree groups 2G_2(q) = Ree(q), where q = 3^{2m + 1} for
some m > 0, in their natural representations of degree 7. The input is a
generating set X.
The constructive recognition algorithm is polynomial time given a discrete
logarithm oracle. The constructive membership testing consists of a
pre-processing step, that only needs to be executed once for a given X, and a
main step. The latter is polynomial time, and the former is polynomial time
given a discrete logarithm oracle.
Implementations of the algorithms are available for the computer algebra
system MAGMA
U(N) Gauge Theory and Lattice Strings
The U(N) gauge theory on a D-dimensional lattice is reformulated as a theory
of lattice strings (a statistical model of random surfaces). The Boltzmann
weights of the surfaces can have both signs and are tuned so that the
longitudinal modes of the string are elliminated. The U(\infty) gauge theory is
described by noninteracting planar surfaces and the 1/N corrections are
produced by surfaces with higher topology as well as by contact interactions
due to microscopic tubes, trousers, handles, etc. We pay special attention to
the case D=2 where the sum over surfaces can be performed explicitly, and
demonstrate that it reproduces the known exact results for the free energy and
Wilson loops in the continuum limit. In D=4 dimensions, our lattice string
model reproduces the strong coupling phase of the gauge theory. The weak
coupling phase is described by a more complicated string whose world surface
may have windows. A possible integration measure in the space of continuous
surfaces is suggested.Comment: 37 pages, 11 figures not included ; An extended version explaining in
addition the construction of the lattice string ansatz in D >2 dimensions.
(Note that the title has been changed.
Nonabelian Duality and Solvable Large N Lattice Systems
We introduce the basics of the nonabelian duality transformation of SU(N) or
U(N) vector-field models defined on a lattice. The dual degrees of freedom are
certain species of the integer-valued fields complemented by the symmetric
groups' \otimes_{n} S(n) variables. While the former parametrize relevant
irreducible representations, the latter play the role of the Lagrange
multipliers facilitating the fusion rules involved. As an application, I
construct a novel solvable family of SU(N) D-matrix systems graded by the rank
1\leq{k}\leq{(D-1)} of the manifest [U(N)]^{\oplus k} conjugation-symmetry.
Their large N solvability is due to a hidden invariance (explicit in the dual
formulation) which allows for a mapping onto the recently proposed
eigenvalue-models \cite{Dub1} with the largest k=D symmetry. Extending
\cite{Dub1}, we reconstruct a D-dimensional gauge theory with the large N free
energy given (modulo the volume factor) by the free energy of a given proposed
1\leq{k}\leq{(D-1)} D-matrix system. It is emphasized that the developed
formalism provides with the basis for higher-dimensional generalizations of the
Gross-Taylor stringy representation of strongly coupled 2d gauge theories.Comment: TeX, 46 page
DSM-5 criteria for substance use disorders: recommendations and rationale.
Since DSM-IV was published in 1994, its approach to substance use disorders has come under scrutiny. Strengths were identified (notably, reliability and validity of dependence), but concerns have also arisen. The DSM-5 Substance-Related Disorders Work Group considered these issues and recommended revisions for DSM-5. General concerns included whether to retain the division into two main disorders (dependence and abuse), whether substance use disorder criteria should be added or removed, and whether an appropriate substance use disorder severity indicator could be identified. Specific issues included possible addition of withdrawal syndromes for several substances, alignment of nicotine criteria with those for other substances, addition of biomarkers, and inclusion of nonsubstance, behavioral addictions.This article presents the major issues and evidence considered by the work group, which included literature reviews and extensive new data analyses. The work group recommendations for DSM-5 revisions included combining abuse and dependence criteria into a single substance use disorder based on consistent findings from over 200,000 study participants, dropping legal problems and adding craving as criteria, adding cannabis and caffeine withdrawal syndromes, aligning tobacco use disorder criteria with other substance use disorders, and moving gambling disorders to the chapter formerly reserved for substance-related disorders. The proposed changes overcome many problems, while further studies will be needed to address issues for which less data were available
Prevalence and determinants of the use of self-tests by members of the public: a mixed methods study
Background
Self-tests can be used by members of the public to diagnose conditions without involving a doctor, nurse or other health professional. As technologies to design and manufacture diagnostic tests have developed, a range of self-tests have become available to the public to buy over-the-counter and via the Internet. This study aims to describe how many people have used self-tests and identify factors associated with their use.
Methods
A postal questionnaire will elicit basic information, including sociodemographic characteristics, and whether the person has used or would use specified self-tests. Consent will be sought to recontact people who want to participate further in the study, and interviews and focus groups will be used to develop hypotheses about factors associated with self-test use. These hypotheses will be tested in a case-control study. An in-depth questionnaire will be developed incorporating the identified factors. This will be sent to: people who have used a self-test (cases); people who have not used a self-test but would use one in the future (controls); and people who have not used and would not use a self-test (controls). Logistic regression analysis will be used to establish which factors are associated with self-test use.
Discussion
Self-tests do have potential benefits, for example privacy and convenience, but also potential harms, for example delay seeking treatment after a true negative result when the symptoms are actually due to another condition. It is anticipated that the outcomes from this study will include recommendations about how to improve the appropriate use of self-tests and existing health services, as well as information to prepare health professionals for patients who have used self-tests
Shocks and dust survival in nearby active galaxies: implications for the alignment effect
One of the most popular explanations for the so-called alignment effect in
high redshift (z>0.7) radio galaxies is the scattering by dust of the hidden
quasar light. As shown by De Young (1998) a problem with the dust scattering
model is that the short destruction time-scale for dust grains means that they
will not survive the passage of the radio jet.
We investigate the survival of dust in the extended ionised gas of nearby
active galaxies with jet/gas interactions. We discuss the implications on the
alignment effect of high redshift (>0.7) radio galaxies. We conclude that
although shocks are likely to destroy dust grains in regions of interaction,
dust might survive in enough quantities to scatter light from the active
nucleus and produce alignment between scattered light and the radio structures.
We propose an observational test to investigate the existence of dust in
shocked regions based on the sensitivity of calcium to depletion onto dust
grains.Comment: 8 pages, 1 Figure, 3 tables, accepted for publication in MNRA
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