1,741 research outputs found
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Scotland, Nuclear Energy Policy and Independance
This paper examines the role of nuclear energy in Scotland, and the concerns for Scotland as it votes for independence. The aim is to focus directly on current Scottish energy policy and its relationship to nuclear energy. The paper does not purport to advise on a vote for or against Scottish independence but aims to further the debate in an underexplored area of energy policy that will be of value whether Scotland secures independence or further devolution. There are four central parts to this paper: (1) consideration of the Scottish electricity mix; (2) an analysis of a statement about nuclear energy made by the Scottish energy minister; (3) examination of nuclear energy issues as presented in the Scottish Independence White Paper; and (4) the issue of nuclear waste is assessed. A recurrent theme in the analysis is that whether one is for, against, or indifferent to new nuclear energy development, it highlights a major gap in Scotland's energy and environmental policy goals. Too often, the energy policy debate from the Scottish Government perspective has been reduced to a low-carbon energy development debate between nuclear energy and renewable energy. There is little reflection on how to reduce Scottish dependency on fossil fuels. For Scotland to aspire to being a low-carbon economy, to decarbonising its electricity market, and to being a leader within the climate change community, it needs to tackle the issue of how to stop the continuation of burning fossil fuels
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The siting of UK Nuclear Power Installations
choosing a suitable site for a nuclear installation requires the consideration and balancin9 of several factors which are sometimes in tension with one another. One particularly interesting tension is a human and demographic one. On the one hand it is beneficial to place nuclear stations close to centres of population, to reduce transmission losses and other costs (including to the local environment) of transporting electricity over large distances from generator to consumer. On the other it is advantageous to place nuclear stations some distance away from such population centres in order to minimise the potential human consequences of a major release of radioactive materials in the (extremely unlikely) event of a major nuclear accident, not only in terms of direct exposure but also concerning the management of emergency planning, notably evacuation. This paper considers the emergence of policies aimed at managing this tension in the UK. In the first phase of nuclear development (roughly speaking 1945 to 1965) there was a highly cautious attitude, with installations being placed in remote rural locations with verylow population density. The second phase (1965 to 1985) saw a more relaxed approach allowin9 Advanced Gas-Cooled Reactor construction closer to population centres (in 'semi-urban' locations, notably at Hartlepool and Heysham). In the third phase (1985 to 2005) there was very little new nuclear development, Sizewell B (the first and so far only pressurised water power reactor in the UK) being co-located with an early Magnox station on the rural Suffolk coast. However, there was considerable effort expended on trying to find a site for disposal of radioactive wastes. Renewed interest in nuclear new build grew from 2005 onwards and led to a number of sites being identified for new reactors before 2025; all having previously hosted nuclear stations and including the semi-urban locations of the 1960s and 1970s. Finally, some speculative comments are made as to what a 'fifth phase' starting in 2025 might look like
Large-Scale Image Processing with the ROTSE Pipeline for Follow-Up of Gravitational Wave Events
Electromagnetic (EM) observations of gravitational-wave (GW) sources would
bring unique insights into a source which are not available from either channel
alone. However EM follow-up of GW events presents new challenges. GW events
will have large sky error regions, on the order of 10-100 square degrees, which
can be made up of many disjoint patches. When searching such large areas there
is potential contamination by EM transients unrelated to the GW event.
Furthermore, the characteristics of possible EM counterparts to GW events are
also uncertain. It is therefore desirable to be able to assess the statistical
significance of a candidate EM counterpart, which can only be done by
performing background studies of large data sets. Current image processing
pipelines such as that used by ROTSE are not usually optimised for large-scale
processing. We have automated the ROTSE image analysis, and supplemented it
with a post-processing unit for candidate validation and classification. We
also propose a simple ad hoc statistic for ranking candidates as more likely to
be associated with the GW trigger. We demonstrate the performance of the
automated pipeline and ranking statistic using archival ROTSE data. EM
candidates from a randomly selected set of images are compared to a background
estimated from the analysis of 102 additional sets of archival images. The
pipeline's detection efficiency is computed empirically by re-analysis of the
images after adding simulated optical transients that follow typical light
curves for gamma-ray burst afterglows and kilonovae. We show that the automated
pipeline rejects most background events and is sensitive to simulated
transients to limiting magnitudes consistent with the limiting magnitude of the
images
Electrochemical Treatment of Mixed and Hazardous Waste
Los Alamos National Laboratory (LANL) and The University of New Mexico are jointly developing an electrochemical process for treating hazardous and radioactive wastes. The wastes treatable by the process include toxic metal solutions, cyanide solutions, and various organic wastes that may contain chlorinated organic compounds. The main component of the process is a stack of electrolytic cells with peripheral equipment such as a rectifier, feed system, tanks with feed and treated solutions, and a gas-venting system. During the treatment, toxic metals are deposited on the cathode, cyanides are oxidized on the anode, and organic compounds are anodically oxidized by direct or mediated electrooxidation, depending on their type. Bench scale experimental studies have confirmed the feasibility of applying electrochemical systems to processing of a great variety of hazardous and mixed wastes. The operating parameters have been defined for different waste compositions using surrogate wastes. Mixed wastes are currently treated at bench scale as part of the treatability study
Neuronal regulation of cochlear blood flow in the guinea‐pig.
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110011/1/tjp19944803563.pd
Enhancing gravitational wave astronomy with galaxy catalogues
Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key
research direction in multi-messenger astronomy, will provide deep insight into
the astrophysics of a vast range of astronomical phenomena. Uncertainties in
the source sky location estimate from gravitational wave observations mean
follow-up observatories must scan large portions of the sky for a potential
companion signal. A general frame of joint GW-EM observations is presented by a
multi-messenger observational triangle. Using a Bayesian approach to
multi-messenger astronomy, we investigate the use of galaxy catalogue and host
galaxy information to reduce the sky region over which follow-up observatories
must scan, as well as study its use for improving the inclination angle
estimates for coalescing binary compact objects. We demonstrate our method
using a simulated neutron stars inspiral signal injected into simulated
Advanced detectors noise and estimate the injected signal sky location and
inclination angle using the Gravitational Wave Galaxy Catalogue. In this case
study, the top three candidates in rank have , and posterior
probability of being the host galaxy, receptively. The standard deviation of
cosine inclination angle (0.001) of the neutron stars binary using
gravitational wave-galaxy information is much smaller than that (0.02) using
only gravitational wave posterior samples.Comment: Proceedings of the Sant Cugat Forum on Astrophysics. 2014 Session on
'Gravitational Wave Astrophysics
Universal Window for Two Dimensional Critical Exponents
Two dimensional condensed matter is realised in increasingly diverse forms
that are accessible to experiment and of potential technological value. The
properties of these systems are influenced by many length scales and reflect
both generic physics and chemical detail. To unify their physical description
is therefore a complex and important challenge. Here we investigate the
distribution of experimentally estimated critical exponents, , that
characterize the evolution of the order parameter through the ordering
transition. The distribution is found to be bimodal and bounded within a window
, facts that are only in partial agreement with
the established theory of critical phenomena. In particular, the bounded nature
of the distribution is impossible to reconcile with existing theory for one of
the major universality classes of two dimensional behaviour - the XY model with
four fold crystal field - which predicts a spectrum of non-universal exponents
bounded only from below. Through a combination of numerical and renormalization
group arguments we resolve the contradiction between theory and experiment and
demonstrate how the "universal window" for critical exponents observed in
experiment arises from a competition between marginal operators.Comment: 26 pages, 5 figures and 6 tables. Uses longtable packag
A List of Galaxies for Gravitational Wave Searches
We present a list of galaxies within 100 Mpc, which we call the Gravitational
Wave Galaxy Catalogue (GWGC), that is currently being used in follow-up
searches of electromagnetic counterparts from gravitational wave searches. Due
to the time constraints of rapid follow-up, a locally available catalogue of
reduced, homogenized data is required. To achieve this we used four existing
catalogues: an updated version of the Tully Nearby Galaxy Catalog, the Catalog
of Neighboring Galaxies, the V8k catalogue and HyperLEDA. The GWGC contains
information on sky position, distance, blue magnitude, major and minor
diameters, position angle, and galaxy type for 53,255 galaxies. Errors on these
quantities are either taken directly from the literature or estimated based on
our understanding of the uncertainties associated with the measurement method.
By using the PGC numbering system developed for HyperLEDA, the catalogue has a
reduced level of degeneracies compared to catalogues with a similar purpose and
is easily updated. We also include 150 Milky Way globular clusters. Finally, we
compare the GWGC to previously used catalogues, and find the GWGC to be more
complete within 100 Mpc due to our use of more up-to-date input catalogues and
the fact that we have not made a blue luminosity cut.Comment: Accepted for publication in Classical and Quantum Gravity, 13 pages,
7 figure
Association of A1C and Fasting Plasma Glucose Levels With Diabetic Retinopathy Prevalence in the U.S. Population: Implications for diabetes diagnostic thresholds
Abstract OBJECTIVE To examine the association of A1C levels and fasting plasma glucose (FPG) with diabetic retinopathy in the U.S. population and to compare the ability of the two glycemic measures to discriminate between people with and without retinopathy. RESEARCH DESIGN AND METHODS This study included 1,066 individuals aged ≥40 years from the 2005–2006 National Health and Nutrition Examination Survey. A1C, FPG, and 45° color digital retinal images were assessed. Retinopathy was defined as a level ≥14 on the Early Treatment Diabetic Retinopathy Study severity scale. We used joinpoint regression to identify linear inflections of prevalence of retinopathy in the association between A1C and FPG. RESULTS The overall prevalence of retinopathy was 11%, which is appreciably lower than the prevalence in people with diagnosed diabetes (36%). There was a sharp increase in retinopathy prevalence in those with A1C ≥5.5% or FPG ≥5.8 mmol/l. After excluding 144 people using hypoglycemic medication, the change points for the greatest increase in retinopathy prevalence were A1C 5.5% and FPG 7.0 mmol/l. The coefficients of variation were 15.6 for A1C and 28.8 for FPG. Based on the areas under the receiver operating characteristic curves, A1C was a stronger discriminator of retinopathy (0.71 [95% CI 0.66–0.76]) than FPG (0.65 [0.60 – 0.70], P for difference = 0.009). CONCLUSIONS The steepest increase in retinopathy prevalence occurs among individuals with A1C ≥5.5% and FPG ≥5.8 mmol/l. A1C discriminates prevalence of retinopathy better than FPG. Tests of glycemia and their thresholds for diabetes diagnosis is an area of long-standing debate. The presence of diabetic retinopathy is arguably the best criterion from which to compare glycemic measures because it is a specific and early clinical complication usually related to diabetes, and it represents a specific and relevant clinical end point for judging an alternative test (1). For these reasons, diabetic retinopathy has served as the basis for diagnostic criteria of type 2 diabetes (2–4) and provides the rationale for the American Diabetes Association's recommendation of a threshold of a fasting plasma glucose (FPG) of 7.0 mmol/l to define the presence of diabetes (4,5). However, an analysis of three recent population-based cross-sectional studies suggested that there may be considerable variation across populations and that the association of FPG with retinopathy prevalence may be more of a continuous relationship than previously thought (5). A1C levels are being considered as an alternative diagnostic tool for diabetes diagnosis (6). Unlike FPG, A1C does not require an overnight fast, is not affected by short-term lifestyle changes, and has less variability within individuals than FPG (7–9). Nevertheless, few studies have examined the prevalence of retinopathy across the spectrum of A1C levels, which could assist in the designation of ideal A1C diagnostic cut points (2,3). The newly released National Health and Nutrition Examination Survey (NHANES) 2005–2006 incorporated a multiple-field retinal photograph examination, presenting an opportunity to reassess the selection of glucose and A1C cut points for diabetes diagnosis. Our objectives were to examine the relation between levels of A1C and FPG and prevalence of retinopathy in the U.S. population and to compare the ability of both measures to differentiate people with and without retinopathy
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