Probing the Relation Between X-ray-Derived and Weak-Lensing-Derived Masses for Shear-Selected Galaxy Clusters: I. A781

We compare X-ray and weak-lensing masses for four galaxy clusters that comprise the top-ranked shear-selected cluster system in the Deep Lens Survey. The weak-lensing observations of this system, which is associated with A781, are from the Kitt Peak Mayall 4-m telescope, and the X-ray observations are from both Chandra and XMM-Newton. For a faithful comparison of masses, we adopt the same matter density profile for each method, which we choose to be an NFW profile. Since neither the X-ray nor weak-lensing data are deep enough to well constrain both the NFW scale radius and central density, we estimate the scale radius using a fitting function for the concentration derived from cosmological hydrodynamic simulations and an X-ray estimate of the mass assuming isothermality. We keep this scale radius in common for both X-ray and weak-lensing profiles, and fit for the central density, which scales linearly with mass. We find that for three of these clusters, there is agreement between X-ray and weak-lensing NFW central densities, and thus masses. For the other cluster, the X-ray central density is higher than that from weak-lensing by 2 sigma. X-ray images suggest that this cluster may be undergoing a merger with a smaller cluster. This work serves as an additional step towards understanding the possible biases in X-ray and weak-lensing cluster mass estimation methods. Such understanding is vital to efforts to constrain cosmology using X-ray or weak-lensing cluster surveys to trace the growth of structure over cosmic time.Comment: 14 pages, 7 figures, matches version in Ap

Judicial Review, Irrationality, and the Legitimacy of Merits-Review

The definition of the irrationality ground of judicial review recognises the constitutional principle of the separation of powers, in allowing for judicial control of the executive only very rarely. The author in a previous article in this study found that the courts, on occasions, had intervened in circumstances where administrative decisions arguably were not irrational. To this end, the purpose of this article is to assess the constitutionality of these seemingly low standards of irrationality. The author does so by reference either to the manner of review employed—the use of the proportionality principle, for example—or the context of the administrative decision under scrutiny, such as the infringement of the applicant’s fundamental rights. The author finds that the cases from the previous article where low standards of irrationality were arguably adopted were, in fact, legitimate according to these chosen methods of evaluation. However, this is an interim conclusion because, for reasons of word length, the author is unable to complete a full assessment here. It is therefore proposed that a subsequent article will continue to examine the constitutionality of these cases. Furthermore, the author will also try and establish a zone of executive decision-making, for reasons of democracy, where the courts are excluded from irrationality review. If the author is unsuccessful in this regard, the final conclusion of this study will inevitably be that low standards of judicial intervention exist without limit—a clear assault on the constitutional principle stated above

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Electroceuticals for Paralympic Athletes:A Fair Play and Classification Concern?

Electroceuticals such as brain computer interfaces and spinal cord stimulation (SCS) represent transformative strategies for neuromodulation. Research has demonstrated that SCS can ameliorate motor and autonomic cardiovascular dysfunctions, particularly in individuals with spinal cord injury (SCI). Notably, SCS has been shown to augment aerobic exercise performance. Owing to the nature of their injury, athletes with SCI are often predisposed to low resting blood pressure and impaired physiological responses to exercise. Therefore, some athletes intentionally induce autonomic dysreflexia (“boosting”) to gain a competitive advantage – an act banned by the International Paralympic Committee (IPC). However, the emergence of electroceuticals facilitates an alternative performance enhancement strategy that could be considered unfair without equal access opportunities for all athletes. Currently, the World Anti-Doping Agency and the IPC have not acknowledged the potential impact of electroceuticals in parasport. Herein, we present an argument that the use of SCS meets the criteria for it to be placed on the World Anti-Doping Code Prohibited List (or at the very least be monitored) because collectively: SCS can enhance sport performance, represents a potential health risk to the athlete if misused, and may violate the spirit of sport. Acute and chronic use of SCS may also lead to classification changes, and increased opportunities for athletes to intentionally misrepresent, thereby raising concerns for the IPC. The growing access to electroceuticals (e.g. via clinical trial participation or private healthcare implantation) more than ever increases the likelihood of an athlete using SCS to gain an unfair advantage in parasport

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Travels in Scottland:Poems for Walter Scott @250

Welcome to the fifth collection by Wyvern Poets, in collaboration with the University of Dundee. 2021 marks the 250th anniversary of the birth of Sir Walter Scott (1771-1832), father of the historical novel and, effectively, of a new kind of mass ‘time travel’. Scott’s prolific output exported an image of his homeland with global appeal, if not always scrupulous authenticity. Stuart Kelly’s 2011 biography, Scott-land, is subtitled The Man Who Invented a Nation, perhaps without too much exaggeration. Scott’s antiquarian vision transformed a turbulent past into a pre-industrial landscape for the Romantic imagination, virtually overwhelming its place of origin or at least melding with it, as he rapidly became one the best-selling authors on earth. John Davidson’s ‘The Salvation of Nature’ (1891), fantasised a future Scotland bought out by an entertainment conglomerate. The World’s Pleasance Company, Ltd. demolishes anything built after 1700, ‘rewilding’ Scotland into a kind of neo-medieval theme park re-staging the past for tourists. Davidson’s story was both satirical exaggeration and backhanded tribute to Scott’s work for bringing history to life in a certain form. Hence this collection considers the many ways in which Scott’s evocative, but also problematic reimagining of his homeland remains relevant to our time and beyond