Octahedron-based Projections as Intermediate Representations for Computer Imaging: TOAST, TEA, and More

This paper defines and discusses a set of rectangular all-sky projections that have no singular points, notably the Tesselated Octahedral Adaptive Spherical Transformation (or TOAST) developed initially for the WorldWide Telescope. These have proven to be useful as intermediate representations for imaging data where the application transforms dynamically from a standardized internal format to a specific format (projection, scaling, orientation, etc.) requested by the user. TOAST is strongly related to the Hierarchical Triangular Mesh pixelization and is particularly well adapted to situations where one wishes to traverse a hierarchy of images increasing in resolution. Because it can be recursively computed using a very simple algorithm it is particularly adaptable to use with graphical processing units

Using Virtual Observatory Services in Sky View

For over a decade Skyview has provided astronomers and the public with easy access to survey and imaging data from all wavelength regimes. SkyView has pioneered many of the concepts that underlie the Virtual Observatory. Recently SkyView has been released as a distributable package which uses VO protocols to access image and catalog services. This chapter describes how to use the Skyview as a local service and how to customize it to access additional VO services and local data

Running a distributed virtual observatory: US Virtual Astronomical Observatory operations

Operation of the US Virtual Astronomical Observatory shares some issues with modern physical observatories, e.g., intimidating data volumes and rapid technological change, and must also address unique concerns like the lack of direct control of the underlying and scattered data resources, and the distributed nature of the observatory itself. In this paper we discuss how the VAO has addressed these challenges to provide the astronomical community with a coherent set of science-enabling tools and services. The distributed nature of our virtual observatory-with data and personnel spanning geographic, institutional and regime boundaries-is simultaneously a major operational headache and the primary science motivation for the VAO. Most astronomy today uses data from many resources. Facilitation of matching heterogeneous datasets is a fundamental reason for the virtual observatory. Key aspects of our approach include continuous monitoring and validation of VAO and VO services and the datasets provided by the community, monitoring of user requests to optimize access, caching for large datasets, and providing distributed storage services that allow user to collect results near large data repositories. Some elements are now fully implemented, while others are planned for subsequent years. The distributed nature of the VAO requires careful attention to what can be a straightforward operation at a conventional observatory, e.g., the organization of the web site or the collection and combined analysis of logs. Many of these strategies use and extend protocols developed by the international virtual observatory community.Comment: 7 pages with 2 figures included within PD

OMCat: Catalogue of Serendipitous Sources Detected with the XMM-Newton Optical Monitor

The Optical Monitor Catalogue of serendipitous sources (OMCat) contains entries for every source detected in the publicly available XMM-Newton Optical Monitor (OM) images taken in either the imaging or ``fast'' modes. Since the OM is coaligned and records data simultaneously with the X-ray telescopes on XMM-Newton, it typically produces images in one or more near-UV/optical bands for every pointing of the observatory. As of the beginning of 2006, the public archive had covered roughly 0.5% of the sky in 2950 fields. The OMCat is not dominated by sources previously undetected at other wavelengths; the bulk of objects have optical counterparts. However, the OMCat can be used to extend optical or X-ray spectral energy distributions for known objects into the ultraviolet, to study at higher angular resolution objects detected with GALEX, or to find high-Galactic-latitude objects of interest for UV spectroscopy.Comment: 25 pages, 22 figures, submitted to PAS

Time-Dependence of the Mass Accretion Rate in Cluster Cooling Flows

We analyze two time-dependent cluster cooling flow models in spherical symmetry. The first assumes that the intracluster gas resides in a static external potential, and includes the effects of optically thin radiative cooling and mass deposition. This corresponds to previous steady-state cooling flow models calculated by White & Sarazin (1987). Detailed agreement is found between steady-state models and time-dependent models at fixed times in the simulations. The mass accretion rate is found either to increase or remain nearly constant once flows reach a steady state. The time rate of change of the accretion rate is strongly sensitive to the value of the mass deposition parameter q, but only mildly sensitive to the ratio beta of gravitational binding energy to gas temperature. We show that previous scaling arguments presented by Bertschinger (1988) and White (1988) are valid only for mature cooling flows with weak mass deposition (q ~< 1). The second set of models includes the effects of a secularly deepening cluster potential and secondary infall of gas from the Hubble flow. We find that such heating effects do not prevent the flows from reaching a steady state within an initial central cooling time.Comment: 22 pages (AASTeX) with 16 EPS figures; accepted for publication in The Astrophysical Journa

Subgroup characteristics of marine methane-oxidizing ANME-2 archaea and their syntrophic partners revealed by integrated multimodal analytical microscopy

Phylogenetically diverse environmental ANME archaea and sulfate-reducing bacteria cooperatively catalyze the anaerobic oxidation of methane oxidation (AOM) in multicelled consortia within methane seep environments. To better understand these cells and their symbiotic associations, we applied a suite of electron microscopy approaches, including correlative fluorescence in situ hybridization-electron microscopy (FISH-EM), transmission electron microscopy (TEM), and serial block face scanning electron microscopy (SBEM) three-dimensional (3D) reconstructions. FISH-EM of methane seep-derived consortia revealed phylogenetic variability in terms of cell morphology, ultrastructure, and storage granules. Representatives of the ANME-2b clade, but not other ANME-2 groups, contained polyphosphate-like granules, while some bacteria associated with ANME-2a/2c contained two distinct phases of iron mineral chains resembling magnetosomes. 3D segmentation of two ANME-2 consortium types revealed cellular volumes of ANME and their symbiotic partners that were larger than previous estimates based on light microscopy. Polyphosphate-like granule-containing ANME (tentatively termed ANME-2b) were larger than both ANME with no granules and partner bacteria. This cell type was observed with up to 4 granules per cell, and the volume of the cell was larger in proportion to the number of granules inside it, but the percentage of the cell occupied by these granules did not vary with granule number. These results illuminate distinctions between ANME-2 archaeal lineages and partnering bacterial populations that are apparently unified in their ability to perform anaerobic methane oxidation

The dynamics of quality: a national panel study of evidence-based standards

This is the final version of the article. Available from NIHR Health Technology Assessment Programme via the DOI in this record.Background Shortfalls in the receipt of recommended health care have been previously reported in England, leading to preventable poor health. Objectives To assess changes over 6 years in the receipt of effective health-care interventions for people aged 50 years or over in England with cardiovascular disease, depression, diabetes or osteoarthritis; to identify how quality varied with participant characteristics; and to compare the distribution of illness burden in the population with the distributions of diagnosis and treatment. Setting and participants Information on health-care quality indicators and participant characteristics was collected using face-to-face structured interviews and nurse visits in participants’ homes by the English Longitudinal Study of Ageing in 2004–5, 2006–7, 2008–9 and 2010–11. A total of 16,773 participants aged 50 years or older were interviewed at least once and 5114 were interviewed in all four waves; 5404 reported diagnosis of one or more of four conditions in 2010–11. Main outcome measures Percentage of indicated health care received by eligible participants for 19 quality indicators: seven for cardiovascular disease, three for depression, five for diabetes and four for osteoarthritis, and condition-level quality indicator achievement, including achievement of a bundle of three diabetes indicators. Analysis Changes in quality indicator achievement over time and variations in quality with participant characteristics were tested with Pearson’s chi-squared test and logistic regression models. The size of inequality between the hypothetically wealthiest and poorest participants, for illness burden, diagnosis and treatment, was estimated using slope indices of wealth inequality. Results Achievement of indicators for cardiovascular disease was 82.7% [95% confidence interval (CI) 79.9% to 85.5%] in 2004–5 and 84.2% (95% CI 82.1% to 86.2%) in 2010–11, for depression 63.3% (95% CI 57.6% to 69.0%) and 59.8% (95% CI 52.4% to 64.3%), for diabetes 76.0% (95% CI 74.1% to 77.8%) and 76.5% (95% CI 74.8% to 78.1%), and for osteoarthritis 31.2% (95% CI 28.5% to 33.8%) and 35.6% (95% CI 34.2% to 37.1%). Achievement of the diabetes care bundle was 67.8% (95% CI 64.5% to 70.9%) in 2010–11. Variations in quality by participant characteristics were generally small. Diabetes indicator achievement was worse in participants with cognitive impairment [odds ratio (OR) 0.5, 95% CI 0.4 to 0.7] and better in those living alone (OR 1.7, 95% CI 1.3 to 2.0). Hypertension care was better for those aged over 74 years (vs. 50–64 years) (OR 3.2, 95% CI 2.0 to 5.3). Osteoarthritis care was better for those with severe (vs. mild) pain (OR 1.8, 95% CI 1.4 to 2.2), limiting illness (OR 1.8, 95% CI 1.5 to 2.1), and obesity (OR 1.6, 95% CI 1.2 to 2.0). Previous non-achievement of the diabetes care bundle was the biggest predictor of non-achievement 2 years later (OR 3.3, 95% CI 2.2 to 4.7). Poorer participants were always more likely than wealthier participants to have illness burden (statistically significant OR 3.9 to 16.0), but not always more likely to be diagnosed or receive treatment (0.2 to 5.3). Conclusions Shortfalls in quality of care for these four conditions have persisted over 6 years, with only half of the level of indicated health care achieved for osteoarthritis, compared with the other three conditions. Quality for osteoarthritis improved slightly over time but remains poor. The relatively high prevalence of specific illness burden in poorer participants was not matched by an equally high prevalence of diagnosis or treatment, suggesting that barriers to equity may exist at the stage at diagnosis. Further research is needed into the association between quality and health system characteristics at the level of clinicians, general practices or hospitals, and regions. Linkage to routinely collected data could provide information on health service characteristics at the individual patient level.Funding for this study was provided by the Health Services and Delivery Research programme of the National Institute for Health Research

Incorporating statistical uncertainty in the use of physician cost profiles

<p>Abstract</p> <p>Background</p> <p>Physician cost profiles (also called efficiency or economic profiles) compare the costs of care provided by a physician to his or her peers. These profiles are increasingly being used as the basis for policy applications such as tiered physician networks. Tiers (low, average, high cost) are currently defined by health plans based on percentile cut-offs which do not account for statistical uncertainty. In this paper we compare the percentile cut-off method to another method, using statistical testing, for identifying high-cost or low-cost physicians.</p> <p>Methods</p> <p>We created a claims dataset of 2004-2005 data from four Massachusetts health plans. We employed commercial software to create episodes of care and assigned responsibility for each episode to the physician with the highest proportion of professional costs. A physicians' cost profile was the ratio of the sum of observed costs divided by the sum of expected costs across all assigned episodes. We discuss a new method of measuring standard errors of physician cost profiles which can be used in statistical testing. We then assigned each physician to one of three cost categories (low, average, or high cost) using two methods, percentile cut-offs and a t-test (p-value ≤ 0.05), and assessed the level of disagreement between the two methods.</p> <p>Results</p> <p>Across the 8689 physicians in our sample, 29.5% of physicians were assigned a different cost category when comparing the percentile cut-off method and the t-test. This level of disagreement varied across specialties (17.4% gastroenterology to 45.8% vascular surgery).</p> <p>Conclusions</p> <p>Health plans and other payers should incorporate statistical uncertainty when they use physician cost-profiles to categorize physicians into low or high-cost tiers.</p

Formation of Cool Cores in Galaxy Clusters via Hierarchical Mergers

We present a new scenario for the formation of cool cores in rich galaxy clusters based on results from recent high spatial dynamic range, adaptive mesh Eulerian hydrodynamic simulations of large-scale structure formation. We find that cores of cool gas, material that would be identified as a classical cooling flow based on its X-ray luminosity excess and temperature profile, are built from the accretion of discrete, stable subclusters. Any ``cooling flow'' present is overwhelmed by the velocity field within the cluster - the bulk flow of gas through the cluster typically has speeds up to about 2,000 km s^-1 and significant rotation is frequently present in the cluster core. The inclusion of consistent initial cosmological conditions for the cluster within its surrounding supercluster environment is crucial when simulating the evolution of cool cores in rich galaxy clusters. This new model for the hierarchical assembly of cool gas naturally explains the high frequency of cool cores in rich galaxy clusters despite the fact that a majority of these clusters show evidence of substructure which is believed to arise from recent merger activity. Furthermore, our simulations generate complex cluster cores in concordance with recent X-ray observations of cool fronts, cool ``bullets'', and filaments in a number of galaxy clusters. Our simulations were computed with a coupled N-body, Eulerian, adaptive mesh refinement, hydrodynamics cosmology code that properly treats the effects of shocks and radiative cooling by the gas. We employ up to seven levels of refinement to attain a peak resolution of 15.6 h^-1 kpc within a volume 256 h-1 Mpc on a side and assume a standard LambdaCDM cosmology.Comment: To appear in ApJ, 41 pages, 20 Figures and 2 Tables. Full resolution figures are available at http://casa.colorado.edu/~motl/astro-p