6,347 research outputs found

    Automated mass spectrometer/analysis system: A concept

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    System performs rapid multiple analyses of entire compound classes or individual compounds on small amounts of sample and reagent. Method will allow screening of large populations for metabolic disorders and establishment of effective-but-safe levels of therapeutic drugs in body fluids and tissues

    Quasinormal Modes, the Area Spectrum, and Black Hole Entropy

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    The results of canonical quantum gravity concerning geometric operators and black hole entropy are beset by an ambiguity labelled by the Immirzi parameter. We use a result from classical gravity concerning the quasinormal mode spectrum of a black hole to fix this parameter in a new way. As a result we arrive at the Bekenstein - Hawking expression of A/4lP2A/4 l_P^2 for the entropy of a black hole and in addition see an indication that the appropriate gauge group of quantum gravity is SO(3) and not its covering group SU(2).Comment: 4 pages, 2 figure

    Chandra Observations of Extended X-ray Emission in Arp 220

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    We resolve the extended X-ray emission from the prototypical ultraluminous infrared galaxy Arp 220. Extended, faint edge-brightened, soft X-ray lobes outside the optical galaxy are observed to a distance of 10 to 15 kpc on each side of the nuclear region. Bright plumes inside the optical isophotes coincide with the optical line emission and extend 11 kpc from end to end across the nucleus. The data for the plumes cannot be fit by a single temperature plasma, and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from bright, diffuse circumnuclear emission in the inner 3 kpc centered on the Halpha peak, which is displaced from the radio nuclei. There is a close morphological correspondence between the Halpha and soft X-ray emission on all spatial scales. We interpret the plumes as a starburst-driven superwind, and discuss two interpretations of the emission from the lobes in the context of simulations of the merger dynamics of Arp 220.Comment: Accepted for publication in ApJ; see also astro-ph/0208477 (Paper 1

    M/L, H-alpha Rotation Curves, and HI Measurements for 329 Nearby Cluster and Field Spirals: II. Evidence for Galaxy Infall

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    We have conducted a study of optical and HI properties of spiral galaxies (size, luminosity, H-alpha flux distribution, circular velocity, HI gas mass) to explore the role of gas stripping as a driver of morphological evolution in clusters. We find a strong correlation between the spiral and S0 fractions within clusters, and the spiral fraction scales tightly with cluster X-ray gas luminosity. We explore young star formation and identify spirals that are (1) asymmetric, with truncated H-alpha emission and HI gas reservoirs on the leading edge of the disk, on a first pass through the dense intracluster medium in the cores of rich clusters; (2) strongly HI deficient and stripped, with star formation confined to the inner 5 kpc/h and 3 disk scale lengths; (3) reddened, extremely HI deficient and quenched, where star formation has been halted across the entire disk. We propose that these spirals are in successive stages of morphological transformation, between infalling field spirals and cluster S0s, and that the process which acts to remove the HI gas reservoir suppresses new star formation on a similarly fast timescale. These data suggest that gas stripping plays a significant role in morphological transformation and rapid truncation of star formation across the disk.Comment: 24 pages, 12 figures; accepted for publication in AJ; higher-resolution figures available at http://astronomy.nmsu.edu/nicol

    Riemann solvers and undercompressive shocks of convex FPU chains

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    We consider FPU-type atomic chains with general convex potentials. The naive continuum limit in the hyperbolic space-time scaling is the p-system of mass and momentum conservation. We systematically compare Riemann solutions to the p-system with numerical solutions to discrete Riemann problems in FPU chains, and argue that the latter can be described by modified p-system Riemann solvers. We allow the flux to have a turning point, and observe a third type of elementary wave (conservative shocks) in the atomistic simulations. These waves are heteroclinic travelling waves and correspond to non-classical, undercompressive shocks of the p-system. We analyse such shocks for fluxes with one or more turning points. Depending on the convexity properties of the flux we propose FPU-Riemann solvers. Our numerical simulations confirm that Lax-shocks are replaced by so called dispersive shocks. For convex-concave flux we provide numerical evidence that convex FPU chains follow the p-system in generating conservative shocks that are supersonic. For concave-convex flux, however, the conservative shocks of the p-system are subsonic and do not appear in FPU-Riemann solutions

    Healthy lifestyle interventions in general practice: Part16: Lifestyle and fibromyalgia

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    Fibromyalgia is a chronic disorder, characterised by chronic widespread musculoskeletal pain, and the presence of multiple tender points as well as a host of associated symptomatology. Optimal management of patients with fibromyalgia requires a multidisciplinary approach, with a combination of pharmacological and non-pharmacological interventions that are tailored to the patient's pain, dysfunction and associated features, including depression, sleep disorder and fatigue. Non-pharmacological lifestyle-based interventions to treat this disorder include exercise therapy, dietary modification, and psychosocial interventions. This review outlines these three forms of lifestyle intervention in patients with fibromyalgia

    Healthy lifestyle interventions in general practice Part 4: Lifestyle and diabetes mellitus

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    Diabetes mellitus, in particular Type 2 diabetes, can be classified as a chronic disease of lifestyle. A lifestyle intervention programme is therefore an essential component of the primary and secondary prevention (management) of diabetes mellitus. The main indication for referral to a lifestyle intervention programme is any patient with either pre-diabetes or established diabetes mellitus. Following a comprehensive initial assessment, patients are recommended to attend either a group-based programme (medically supervised or medically directed, depending on the severity of the disease and the presence of any co-morbidities) or a home-based intervention programme. The main elements of the intervention programme are nutritional intervention, exercise training (minimum of 150 minutes at moderate intensity per week), psychosocial support and education. Regular monitoring should be conducted during training sessions, and a follow-up assessment is indicated after 2–3 months to assess progress and to re-set goals. Longer-term (5–6 months) intervention programmes are associated with better long-term outcomes
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