1,411 research outputs found
A Tool for Global Resilience Analysis of Water Distribution Systems
This is a joint publication in collaboration with Centre for Water Systems at University of Exeter. This research is based on my previous work for Prof. Butler's project of "Safe and SuRe: A New Paradigm for Urban Water Management".A comprehensive assessment of resilience requires consideration of system performance under exceptional conditions, including those that are unforeseen, and can be achieved using a previously developed methodology called âglobal resilience analysisâ (GRA). GRA captures the effects of both probable and highly improbable (unknown probability) system failures and requires no knowledge of threats. Here, a simple, user-friendly tool that automates the simulations required for GRA of a water distribution system and assists comprehension of the results is presented. Provided the user can supply an Epanet .inp file for the system and that this contains demand data (an understanding of Epanet and system failure modelling is not necessary), the tool can be used to quantify the resilience of the system to pipe failure, pump failure, demand increase and contaminant intrusion. An interactive results explorer allows the user to easily identify critical system components based on the selected level of service type and failure measure (e.g. pressure, supply or contamination and failure magnitude or duration). A map of the network can be used to either color-code components based on their criticality in a single component failure analysis or to identify specific combinations of components which result in the greatest level of service failure magnitude or duration when failed simultaneously. âStress-strainâ type response curves can also be automatically generated and key findings automatically extracted. Additionally, the tool enables systems to be compared on a like-for-like basis, enabling the effects of proposed interventions on resilience to be quantified and visualized
High eccentricity planets from the Anglo-Australian Planet Search
We report Doppler measurements of the stars HD187085 and HD20782 which
indicate two high eccentricity low-mass companions to the stars. We find
HD187085 has a Jupiter-mass companion with a ~1000d orbit. Our formal `best
fit' solution suggests an eccentricity of 0.47, however, it does not sample the
periastron passage of the companion and we find that orbital solutions with
eccentricities between 0.1 and 0.8 give only slightly poorer fits (based on RMS
and chi^2) and are thus plausible. Observations made during periastron passage
in 2007 June should allow for the reliable determination of the orbital
eccentricity for the companion to HD187085. Our dataset for HD20782 does sample
periastron and so the orbit for its companion can be more reliably determined.
We find the companion to HD20782 has M sin i=1.77+/-0.22M_JUP, an orbital
period of 595.86+/-0.03d and an orbit with an eccentricity of 0.92+/-0.03. The
detection of such high-eccentricity (and relatively low velocity amplitude)
exoplanets appears to be facilitated by the long-term precision of the
Anglo-Australian Planet Search. Looking at exoplanet detections as a whole, we
find that those with higher eccentricity seem to have relatively higher
velocity amplitudes indicating higher mass planets and/or an observational bias
against the detection of high eccentricity systems.Comment: to appear in MNRA
Potential for Solar System Science with the ngVLA
Radio wavelength observations of solar system bodies are a powerful method of
probing many characteristics of those bodies. From surface and subsurface, to
atmospheres (including deep atmospheres of the giant planets), to rings, to the
magnetosphere of Jupiter, these observations provide unique information on
current state, and sometimes history, of the bodies. The ngVLA will enable the
highest sensitivity and resolution observations of this kind, with the
potential to revolutionize our understanding of some of these bodies. In this
article, we present a review of state-of-the-art radio wavelength observations
of a variety of bodies in our solar system, varying in size from ring particles
and small near-Earth asteroids to the giant planets. Throughout the review we
mention improvements for each body (or class of bodies) to be expected with the
ngVLA. A simulation of a Neptune-sized object is presented in Section 6.
Section 7 provides a brief summary for each type of object, together with the
type of measurements needed for all objects throughout the Solar System
Oscillation frequencies and mode lifetimes in alpha Centauri A
We analyse our recently-published velocity measurements of alpha Cen A
(Butler et al. 2004). After adjusting the weights on a night-by-night basis in
order to optimize the window function to minimize sidelobes, we extract 42
oscillation frequencies with l=0 to 3 and measure the large and small frequency
separations. We give fitted relations to these frequencies that can be compared
with theoretical models and conclude that the observed scatter about these fits
is due to the finite lifetimes of the oscillation modes. We estimate the mode
lifetimes to be 1-2 d, substantially shorter than in the Sun.Comment: Accepted by Ap
Recommended from our members
Self, memory, and imagining the future in a case of psychogenic amnesia
We report a case of psychogenic amnesia and examine the relationships between autobiographical memory impairment, the self, and ability to imagine the future. Case study JH, a 60 year old male, experienced a 6 year period of pervasive psychogenic amnesia covering all life events from childhood to the age of 53. JH was tested during his amnesic period and again following hypnotherapy and the recovery of his memories. JHâs amnesia corresponded with deficits in self-knowledge and imagining the future. Results are discussed with reference to models of self and memory and processes involving remembering and imagining
The Mini-Addenbrooke's Cognitive Examination: a new assessment tool for dementia.
BACKGROUND/AIMS: We developed and validated the Mini-Addenbrooke's Cognitive Examination (M-ACE) in dementia patients. Comparisons were also made with the Mini Mental State Examination (MMSE). METHOD: The M-ACE was developed using Mokken scaling analysis in 117 dementia patients [behavioural variant frontotemporal dementia (bvFTD), n = 25; primary progressive aphasia (PPA), n = 49; Alzheimer's disease (AD), n = 34; corticobasal syndrome (CBS), n = 9] and validated in an independent sample of 164 dementia patients (bvFTD, n = 23; PPA, n = 82; AD, n = 38; CBS, n = 21) and 78 controls, who also completed the MMSE. RESULTS: The M-ACE consists of 5 items with a maximum score of 30. Two cut-offs were identified: (1) â€25/30 has both high sensitivity and specificity, and (2) â€21/30 is almost certainly a score to have come from a dementia patient regardless of the clinical setting. The M-ACE is more sensitive than the MMSE and is less likely to have ceiling effects. CONCLUSION: The M-ACE is a brief and sensitive cognitive screening tool for dementia. Two cut-offs (25 or 21) are recommended.This work was supported by funding to Forefront, a collaborative research group dedicated to the study of frontotemporal dementia and motor neurone disease, by the National Health and Medical Research council (NHMRC) of Australia program grant (1037746) and the Australian Research Council (ARC) Centre of Excellence in Cognition and Its Disorders Memory Node (CE110001021). S.H. is supported by the Graham Linford Fellowship from the Motor Neurone Disease Research Institute of Australia. S.M. is supported by Alzheimer Scotland (PhD Studentship). F.L. is supported by an Australian Postgraduate Award (PhD Scholarship). K.D. is supported by NIHR Cambridge Biomedical Research Centre. S.A. is supported by the NIHR Biomedical Research Centre, Oxford. C.R.B. is supported by a Clinician Scientist Fellowship from the Medical Research Council (MR/K010395/1). J.B.R. is supported by the Wellcome Trust (088324), Medical Research Council, McDonnell Foundation and the NIHR (Cambridge Biomedical Research Centre and Biomedical Research Unit in Dementia). E.M. is supported by the NHMRC Early Career Fellowship (1016399) and Alzheimer Association USA. J.R.H. is supported by an ARC Federation Fellowship (FF0776229).This is the final version of the article. It first appeared from Karger via http://dx.doi.org/10.1159/00036604
The numerical simulation tool for the MAORY multiconjugate adaptive optics system
The Multiconjugate Adaptive Optics RelaY (MAORY) is and Adaptive Optics
module to be mounted on the ESO European-Extremely Large Telescope (E-ELT). It
is a hybrid Natural and Laser Guide System that will perform the correction of
the atmospheric turbulence volume above the telescope feeding the Multi-AO
Imaging Camera for Deep Observations Near Infrared spectro-imager (MICADO). We
developed an end-to-end Monte- Carlo adaptive optics simulation tool to
investigate the performance of a the MAORY and the calibration, acquisition,
operation strategies. MAORY will implement Multiconjugate Adaptive Optics
combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements.
The simulation tool implements the various aspect of the MAORY in an end to end
fashion. The code has been developed using IDL and uses libraries in C++ and
CUDA for efficiency improvements. Here we recall the code architecture, we
describe the modeled instrument components and the control strategies
implemented in the code.Comment: 6 pages, 1 figure, Proceeding 9909 310 of the conference SPIE
Astronomical Telescopes + Instrumentation 2016, 26 June 1 July 2016
Edinburgh, Scotland, U
The microvascular endothelial glycocalyx:An additional piece of the puzzle in veterinary medicine
The endothelial glycocalyx (eGlx) is a critically important structure lining the luminal surface of endothelial cells. There is increasing evidence, in human patients and animal models, for its crucial role in the maintenance of health. Moreover, its damage is associated with the pathogenesis of multiple disease states. This review provides readers with an overview of the eGlx; summarising its structure, essential functions, and evidence for its role in disease. We highlight the lack of studies regarding the eGlx in cats and dogs, particularly in naturally occurring diseases. Importantly, we discuss techniques to aid its study, which can be applied to veterinary species. Finally, we present targeted therapies aimed at preserving, and in some cases, restoring damaged eGlx
The observed distribution of spectroscopic binaries from the Anglo-Australian Planet Search
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We report the detection of sixteen binary systems from the Anglo-Australian Planet Search. Solutions to the radial velocity data indicate that the stars have companions orbiting with a wide range of masses, eccentricities and periods. Three of the systems potentially contain brown-dwarf companions while another two have eccentricities that place them in the extreme upper tail of the eccentricity distribution for binaries with periods less than 1000 d. For periods up to 12 years, the distribution of our stellar companion masses is fairly flat, mirroring that seen in other radial velocity surveys, and contrasts sharply with the current distribution of candidate planetary masses, which rises strongly below 10 MJ. When looking at a larger sample of binaries that have FGK star primaries as a function of the primary star metallicity, we find that the distribution maintains a binary fraction of âŒ43 ± 4âperâcent between â1.0 and +0.6 dex in metallicity. This is in stark contrast to the giant exoplanet distribution. This result is in good agreement with binary formation models that invoke fragmentation of a collapsing giant molecular cloud, suggesting that this is the dominant formation mechanism for close binaries and not fragmentation of the primary star's remnant protoplanetary disc.Peer reviewe
Five Planets Orbiting 55 Cancri
We report 18 years of Doppler shift measurements of a nearby star, 55 Cancri,
that exhibit strong evidence for five orbiting planets. The four previously
reported planets are strongly confirmed here. A fifth planet is presented, with
an apparent orbital period of 260 days, placing it 0.78 AU from the star in the
large empty zone between two other planets. The velocity wobble amplitude of
4.9 \ms implies a minimum planet mass \msini = 45.7 \mearthe. The orbital
eccentricity is consistent with a circular orbit, but modest eccentricity
solutions give similar \chisq fits. All five planets reside in low eccentricity
orbits, four having eccentricities under 0.1. The outermost planet orbits 5.8
AU from the star and has a minimum mass, \msini = 3.8 \mjupe, making it more
massive than the inner four planets combined. Its orbital distance is the
largest for an exoplanet with a well defined orbit. The innermost planet has a
semi-major axis of only 0.038 AU and has a minimum mass, \msinie, of only 10.8
\mearthe, one of the lowest mass exoplanets known. The five known planets
within 6 AU define a {\em minimum mass protoplanetary nebula} to compare with
the classical minimum mass solar nebula. Numerical N-body simulations show this
system of five planets to be dynamically stable and show that the planets with
periods of 14.65 and 44.3 d are not in a mean-motion resonance. Millimagnitude
photometry during 11 years reveals no brightness variations at any of the
radial velocity periods, providing support for their interpretation as
planetary.Comment: accepted to Ap
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