Briefing: Auditor/company interactions in the 2007 UK regulatory environment

No abstract availabl

Relativistic Diskoseismology. I. Analytical Results for 'Gravity Modes'

We generalize previous calculations to a fully relativistic treatment of adiabatic oscillations which are trapped in the inner regions of accretion disks by non-Newtonian gravitational effects of a black hole. We employ the Kerr geometry within the scalar potential formalism of Ipser and Lindblom, neglecting the gravitational field of the disk. This approach treats perturbations of arbitrary stationary, axisymmetric, perfect fluid models. It is applied here to thin accretion disks. Approximate analytic eigenfunctions and eigenfrequencies are obtained for the most robust and observable class of modes, which corresponds roughly to the gravity (internal) oscillations of stars. The dependence of the oscillation frequencies on the mass and angular momentum of the black hole is exhibited. These trapped modes do not exist in Newtonian gravity, and thus provide a signature and probe of the strong-field structure of black holes. Our predictions are relevant to observations which could detect modulation of the X-ray luminosity from stellar mass black holes in our galaxy and the UV and optical luminosity from supermassive black holes in active galactic nuclei.Comment: 31 pages, 6 figures, uses style file aaspp4.sty, prepared with the AAS LATEX macros v4.0, significant revision of earlier submission to include modes with axial index m>

Classical Structures Based on Unitaries

Starting from the observation that distinct notions of copying have arisen in different categorical fields (logic and computation, contrasted with quantum mechanics) this paper addresses the question of when, or whether, they may coincide. Provided all definitions are strict in the categorical sense, we show that this can never be the case. However, allowing for the defining axioms to be taken up to canonical isomorphism, a close connection between the classical structures of categorical quantum mechanics, and the categorical property of self-similarity familiar from logical and computational models becomes apparent. The required canonical isomorphisms are non-trivial, and mix both typed (multi-object) and untyped (single-object) tensors and structural isomorphisms; we give coherence results that justify this approach. We then give a class of examples where distinct self-similar structures at an object determine distinct matrix representations of arrows, in the same way as classical structures determine matrix representations in Hilbert space. We also give analogues of familiar notions from linear algebra in this setting such as changes of basis, and diagonalisation.Comment: 24 pages,7 diagram

Simulation of networks of spiking neurons: A review of tools and strategies

We review different aspects of the simulation of spiking neural networks. We start by reviewing the different types of simulation strategies and algorithms that are currently implemented. We next review the precision of those simulation strategies, in particular in cases where plasticity depends on the exact timing of the spikes. We overview different simulators and simulation environments presently available (restricted to those freely available, open source and documented). For each simulation tool, its advantages and pitfalls are reviewed, with an aim to allow the reader to identify which simulator is appropriate for a given task. Finally, we provide a series of benchmark simulations of different types of networks of spiking neurons, including Hodgkin-Huxley type, integrate-and-fire models, interacting with current-based or conductance-based synapses, using clock-driven or event-driven integration strategies. The same set of models are implemented on the different simulators, and the codes are made available. The ultimate goal of this review is to provide a resource to facilitate identifying the appropriate integration strategy and simulation tool to use for a given modeling problem related to spiking neural networks.Comment: 49 pages, 24 figures, 1 table; review article, Journal of Computational Neuroscience, in press (2007

9.7 um Silicate Features in AGNs: New Insights into Unification Models

We describe observations of 9.7 um silicate features in 97 AGNs, exhibiting a wide range of AGN types and of X-ray extinction toward the central nuclei. We find that the strength of the silicate feature correlates with the HI column density estimated from fitting the X-ray data, such that low HI columns correspond to silicate emission while high columns correspond to silicate absorption. The behavior is generally consistent with unification models where the large diversity in AGN properties is caused by viewing-angle-dependent obscuration of the nucleus. Radio-loud AGNs and radio-quiet quasars follow roughly the correlation between HI columns and the strength of the silicate feature defined by Seyfert galaxies. The agreement among AGN types suggests a high-level unification with similar characteristics for the structure of the obscuring material. We demonstrate the implications for unification models qualitatively with a conceptual disk model. The model includes an inner accretion disk (< 0.1 pc in radius), a middle disk (0.1-10 pc in radius) with a dense diffuse component and with embedded denser clouds, and an outer clumpy disk (10-300 pc in radius).Comment: Accepted for publication in ApJ, 14 pages, 5 figures. The on-line table is available at http://cztsy.as.arizona.edu/~yong/silicate_tab1.pd

Tribes and tribulations: Interdisciplinary eHealth in providing services for people with a traumatic brain injury (TBI)

© 2017 The Author(s). Background: eHealth has potential for supporting interdisciplinary care in contemporary traumatic brain injury (TBI) rehabilitation practice, yet little is known about whether this potential is being realised, or what needs to be done to further support its implementation. The purpose of this study was to explore health professionals' experiences of, and attitudes towards eHealth technologies to support interdisciplinary practice within rehabilitation for people after TBI. Methods: A qualitative study using narrative analysis was conducted. One individual interview and three focus groups were conducted with health professionals (n = 17) working in TBI rehabilitation in public and private healthcare settings across regional and metropolitan New South Wales, Australia. Results: Narrative analysis revealed that participants held largely favourable views about eHealth and its potential to support interdisciplinary practice in TBI rehabilitation. However, participants encountered various issues related to (a) the design of, and access to electronic medical records, (b) technology, (c) eHealth implementation, and (d) information and communication technology processes that disconnected them from the work they needed to accomplish. In response, health professionals attempted to make the most of unsatisfactory eHealth systems and processes, but were still mostly unsuccessful in optimising the quality, efficiency, and client-centredness of their work. Conclusions: Attention to sources of disconnection experienced by health professionals, specifically design of, and access to electronic health records, eHealth resourcing, and policies and procedures related to eHealth and interdisciplinary practice are required if the potential of eHealth for supporting interdisciplinary practice is to be realised

Change in Abundance of Pacific Brant Wintering in Alaska: Evidence of a Climate Warming Effect?

Winter distribution of Pacific Flyway brant (Branta bernicla nigricans) has shifted northward from low-temperate areas to sub-Arctic areas over the last 42 years. We assessed the winter abundance and distribution of brant in Alaska to evaluate whether climate warming may be contributing to positive trends in the most northern of the wintering populations. Mean surface air temperatures during winter at the end of the Alaska Peninsula increased about 1°C between 1963 and 2004, resulting in a 23% reduction in freezing degree days and a 34% decline in the number of days when ice cover prevents birds from accessing food resources. Trends in the wintering population fluctuated with states of the Pacific Decadal Oscillation, increasing during positive (warm) phases and decreasing during negative (cold) phases, and this correlation provides support for the hypothesis that growth in the wintering population of brant in Alaska is linked to climate warming. The size of the wintering population was negatively correlated with the number of days of strong northwesterly winds in November, which suggests that the occurrence of tailwinds favorable for migration before the onset of winter was a key factor in whether brant migrated from Alaska or remained there during winter. Winter distribution of brant on the Alaska Peninsula was highly variable and influenced by ice cover, particularly at the heavily used Izembek Lagoon. Observations of previously marked brant indicated that the Alaska wintering population was composed primarily of birds originating from Arctic breeding colonies that appear to be growing. Numbers of brant in Alaska during winter will likely increase as temperatures rise and ice cover decreases at high latitudes in response to climate warming.Au cours des 42 dernières années, la répartition de la bernache cravant du Pacifique (Branta bernicla nigricans) s’est déplacée vers le nord en hiver, passant ainsi de régions faiblement tempérées à des régions subarctiques. Nous avons évalué l’abondance et la répartition de la bernache en Alaska l’hiver afin de tenter de déterminer si le réchauffement climatique contribue aux tendances positives au sein des populations d’hivernage les plus au nord. Les températures moyennes de l’air à la surface en hiver se sont accrues d’environ 1°C entre 1963 et 2004, ce qui s’est traduit par une réduction de 23 % du nombre de jours atteignant le point de congélation et d’une diminution de 34 % du nombre de jours pendant lesquels la couverture de glace empêche les oiseaux d’avoir accès aux ressources alimentaires. Les tendances caractérisant la population d’hivernage fluctuaient en fonction des états de l’oscillation pacifique décennale en ce sens qu’elles augmentaient pendant les phases positives (tièdes) et qu’elles baissaient pendant les phases négatives (froides). Cette corrélation vient appuyer l’hypothèse selon laquelle la croissance de la population d’hivernage de la bernache en Alaska est liée au réchauffement climatique. L’effectif de la population d’hivernage a été négativement corrélé au nombre de jours de vents forts en provenance du nord-ouest en novembre, ce qui laisse croire que l’occurrence de vents arrières favorables à la migration avant le début de l’hiver constituait un facteur-clé déterminant si une bernache migrait de l’Alaska ou y restait pendant l’hiver. Dans la péninsule de l’Alaska, la répartition de la bernache en hiver variait énormément et dépendait de la couverture de glace, surtout à la lagune Izembek particulièrement achalandée. Les observations de bernaches déjà marquées ont permis de constater que la population d’hivernage de l’Alaska était principalement composée d’oiseaux provenant des colonies de reproduction de l’Arctique qui semblent prendre de l’ampleur. Le nombre de bernaches en Alaska pendant l’hiver augmentera vraisemblablement au fur et à mesure que les températures augmenteront et que les couvertures de glace diminueront en haute latitude en raison du réchauffement climatique

In Vitro Methane Production from Heifers Offered Four Bermudagrass Cultivars

Though bermudagrass (Cynodon dactylon [L.] Pers.) is one of the predominant warm-season perennial forage supporting the southeastern United States livestock production systems, little is known about its influence on parameters of ruminal metabolism, including carbon loss as methane. With the multitude of cultivars of this grass that have been developed and released, one may question whether the physiological cultivar differences will manifest varying results in digestive efficiency and subsequent methane emissions. Thus, the objective of this study was to evaluate in vitro methane (CH4) production as influenced by four bermudagrass cultivars. Ruminally-fistulated heifers (n = 4) were assigned randomly to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods in a Latin square design. On d 28 of each period, rumen fluid was collected from each heifer for use in CH4 production evaluation. Samples of each bermudagrass, corresponding to the cultivar fed, were weighed into duplicate 10-mL serum bottles and incubated at 39°C for 0, 2, 4, and 24 h. Following incubation, headspace samples were assayed for CH4 concentrations by gas chromatography. There was an interaction of cultivar and time (P \u3c 0.01). There was no difference among cultivars (P \u3c 0.05) at 0, 2, or 4 h of incubation. After 24 h of incubation, however, CH4 concentrations were greater (P \u3c 0.05) from T44 and T85 (7.7 and 6.2 mmol/L, respectively) than from RUS and COS (3.4 and 3.0 mmol/L, respectively). Results are interpreted to mean that cultivar type has an influence on the potential CH4 production of bermudagrass