454 research outputs found
Recommended from our members
Whose Global law? Comparative, Regional and Cyber Approaches to Law-Making
The 2019 Global Law Research Dialogue Series convened by Elaine Fahey, Jed Odermatt and Elizabeth O’Loughlin was entitled ‘Whose Global Law? Comparative, Regional and Methodological Lenses’. The series focused on three elements: 1) comparative law approaches to the study of global law, 2) regional approaches to law-making, 2) cyber law-making and methodology, as topical case studies, political problems or eternal legal methodology issues warranting discussions and reflections. The thematic areas selected in 2019, including one case study (Cyber), were chosen for their capacity to generate deliberation as to the global and its complex intersection with inter alia public, private, regional, criminal law and international law – not a conclusive list. The distinctive views of comparative public law and public international law continue to be distinct and separate strands of research warranting further reflection. In keeping with the aims of the series, the 2019 instalment brought together an array of scholars from public and private law, governance, science and technology, political economy and practice to reflect upon our understanding of law beyond the Nation State
Holography for the Lorentz Group Racah Coefficients
A known realization of the Lorentz group Racah coefficients is given by an
integral of a product of 6 ``propagators'' over 4 copies of the hyperbolic
space. These are ``bulk-to-bulk'' propagators in that they are functions of two
points in the hyperbolic space. It is known that the bulk-to-bulk propagator
can be constructed out of two bulk-to-boundary ones. We point out that there is
another way to obtain the same object. Namely, one can use two bulk-to-boundary
and one boundary-to-boundary propagator. Starting from this construction and
carrying out the bulk integrals we obtain a realization of the Racah
coefficients that is ``holographic'' in the sense that it only involves
boundary objects. This holographic realization admits a geometric
interpretation in terms of an ``extended'' tetrahedron.Comment: 12 pages, 2 figures; v2: minor changes; v3: "extended" tetrahedron
interpretation adde
Adapting data collection methods in the Australian life histories and health survey: a retrospective life course study
OBJECTIVE Ideally, life course data are collected prospectively through an ongoing longitudinal study. We report adaptive multimethod fieldwork procedures that gathered life history data by mail survey and telephone interview, comparable with the face-to-face methods employed in the English Longitudinal Study on Ageing (ELSA). DESIGN The Australian Life Histories and Health (LHH) Survey was a substudy of the Australian 45 and Up Study, with data collection methods modified from the ELSA Study. A self-complete questionnaire and life history calendar were completed by the participants, followed by a computer-assisted telephone interview recording key life events. RESULTS The LHH survey developed and tested procedures and instruments that gathered rich life history data within an ongoing Australian longitudinal survey on ageing. Data collection proved to be economical. The use of a self-complete questionnaire in conjunction with a life history calendar and coordinated computer-assisted telephone interview was successful in collecting retrospective life course information, in terms of being thorough, practical and efficient. This study has a diverse collection of data covering the life course, starting with early life experiences and continuing with socioeconomic and health exposures and outcomes during adult life. CONCLUSIONS Mail and telephone methodology can accurately and economically add a life history dimension to an ongoing longitudinal survey. The method is particularly valuable for surveying widely dispersed populations. The results will facilitate understanding of the social determinants of health by gathering data on earlier life exposures as well as comparative data across geographical and societal contexts.Supported by an Australian Research Council Grant (DP 1096778,
“Socio-economic determinants and health inequalities over the life-course:
Australian and English comparisons”) with investigators from the Universities of Sydney, Newcastle and Queensland (Australia) and the University of
Manchester (UK)
Recommended from our members
The impact of uncertain precipitation data on insurance loss estimates using a flood catastrophe model
Catastrophe risk models used by the insurance industry are likely subject to significant uncertainty, but due to their proprietary nature and strict licensing conditions they are not available for experimentation. In addition, even if such experiments were conducted, these would not be repeatable by other researchers because commercial confidentiality issues prevent the details of proprietary catastrophe model structures from being described in public domain documents. However, such experimentation is urgently required to improve decision making in both insurance and reinsurance markets. In this paper we therefore construct our own catastrophe risk model for flooding in Dublin, Ireland, in order to assess the impact of typical precipitation data uncertainty on loss predictions. As we consider only a city region rather than a whole territory and have access to detailed data and computing resources typically unavailable to industry modellers, our model is significantly more detailed than most commercial products. The model consists of four components, a stochastic rainfall module, a hydrological and hydraulic flood hazard module, a vulnerability module, and a financial loss module. Using these we undertake a series of simulations to test the impact of driving the stochastic event generator with four different rainfall data sets: ground gauge data, gauge-corrected rainfall radar, meteorological reanalysis data (European Centre for Medium-Range Weather Forecasts Reanalysis-Interim; ERA-Interim) and a satellite rainfall product (The Climate Prediction Center morphing method; CMORPH). Catastrophe models are unusual because they use the upper three components of the modelling chain to generate a large synthetic database of unobserved and severe loss-driving events for which estimated losses are calculated. We find the loss estimates to be more sensitive to uncertainties propagated from the driving precipitation data sets than to other uncertainties in the hazard and vulnerability modules, suggesting that the range of uncertainty within catastrophe model structures may be greater than commonly believed
Managing plagiarism in programming assignments with blended assessment and randomisation.
Plagiarism is a common concern for coursework in many situations, particularly where electronic solutions can be provided e.g. computer programs, and leads to unreliability of assessment. Written exams are often used to try to deal with this, and to increase reliability, but at the expense of validity. One solution, outlined in this paper, is to randomise the work that is set for students so that it is very unlikely that any two students will be working on exactly the same problem set. This also helps to address the issue of students trying to outsource their work by paying external people to complete their assignments for them. We examine the effectiveness of this approach and others (including blended assessment) by analysing the spread of similarity scores across four different introductory programming assignments to find the natural similarity i.e. the level of similarity that could reasonably occur without plagiarism. The results of the study indicate that divergent assessment (having more than one possible solution) as opposed to convergent assessment (only one solution) is the dominant factor in natural similarity. A key area for further work is to apply the analysis to a larger sample of programming assignments to better understand the impact of different features of the assignment design on natural similarity and hence the detection of plagiarism
New interpretation of variational principles for gauge theories. I. Cyclic coordinate alternative to ADM split
I show how there is an ambiguity in how one treats auxiliary variables in
gauge theories including general relativity cast as 3 + 1 geometrodynamics.
Auxiliary variables may be treated pre-variationally as multiplier coordinates
or as the velocities corresponding to cyclic coordinates. The latter treatment
works through the physical meaninglessness of auxiliary variables' values
applying also to the end points (or end spatial hypersurfaces) of the
variation, so that these are free rather than fixed. [This is also known as
variation with natural boundary conditions.] Further principles of dynamics
workings such as Routhian reduction and the Dirac procedure are shown to have
parallel counterparts for this new formalism. One advantage of the new scheme
is that the corresponding actions are more manifestly relational. While the
electric potential is usually regarded as a multiplier coordinate and Arnowitt,
Deser and Misner have regarded the lapse and shift likewise, this paper's
scheme considers new {\it flux}, {\it instant} and {\it grid} variables whose
corresponding velocities are, respectively, the abovementioned previously used
variables. This paper's way of thinking about gauge theory furthermore admits
interesting generalizations, which shall be provided in a second paper.Comment: 11 page
Are Horned Particles the Climax of Hawking Evaporation?
We investigate the proposal by Callan, Giddings, Harvey and Strominger (CGHS)
that two dimensional quantum fluctuations can eliminate the singularities and
horizons formed by matter collapsing on the nonsingular extremal black hole of
dilaton gravity. We argue that this scenario could in principle resolve all of
the paradoxes connected with Hawking evaporation of black holes. However, we
show that the generic solution of the model of CGHS is singular. We propose
modifications of their model which may allow the scenario to be realized in a
consistent manner.Comment: 26 page
Triangleland. I. Classical dynamics with exchange of relative angular momentum
In Euclidean relational particle mechanics, only relative times, relative
angles and relative separations are meaningful. Barbour--Bertotti (1982) theory
is of this form and can be viewed as a recovery of (a portion of) Newtonian
mechanics from relational premises. This is of interest in the absolute versus
relative motion debate and also shares a number of features with the
geometrodynamical formulation of general relativity, making it suitable for
some modelling of the problem of time in quantum gravity. I also study
similarity relational particle mechanics (`dynamics of pure shape'), in which
only relative times, relative angles and {\sl ratios of} relative separations
are meaningful. This I consider firstly as it is simpler, particularly in 1 and
2 d, for which the configuration space geometry turns out to be well-known,
e.g. S^2 for the `triangleland' (3-particle) case that I consider in detail.
Secondly, the similarity model occurs as a sub-model within the Euclidean
model: that admits a shape--scale split. For harmonic oscillator like
potentials, similarity triangleland model turns out to have the same
mathematics as a family of rigid rotor problems, while the Euclidean case turns
out to have parallels with the Kepler--Coulomb problem in spherical and
parabolic coordinates. Previous work on relational mechanics covered cases
where the constituent subsystems do not exchange relative angular momentum,
which is a simplifying (but in some ways undesirable) feature paralleling
centrality in ordinary mechanics. In this paper I lift this restriction. In
each case I reduce the relational problem to a standard one, thus obtain
various exact, asymptotic and numerical solutions, and then recast these into
the original mechanical variables for physical interpretation.Comment: Journal Reference added, minor updates to References and Figure
Black Hole Remnants and the Information Puzzle
Magnetically charged dilatonic black holes have a perturbatively infinite
ground state degeneracy associated with an infinite volume throat region of the
geometry. A simple argument based on causality is given that these states do
not have a description as ordinary massive particles in a low-energy effective
field theory. Pair production of magnetic black holes in a weak magnetic field
is estimated in a weakly-coupled semiclassical expansion about an instanton and
found to be finite, despite the infinite degeneracy of states. This suggests
that these states may store the information apparently lost in black hole
scattering processes.Comment: 16 pages, revision has 5 figures uuencode
- …