7,924 research outputs found

    A uniform metallicity in the outskirts of massive, nearby galaxy clusters

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    Suzaku measurements of a homogeneous metal distribution of Z0.3Z\sim0.3 Solar in the outskirts of the nearby Perseus cluster suggest that chemical elements were deposited and mixed into the intergalactic medium before clusters formed, likely over 10 billion years ago. A key prediction of this early enrichment scenario is that the intracluster medium in all massive clusters should be uniformly enriched to a similar level. Here, we confirm this prediction by determining the iron abundances in the outskirts (r>0.25r200r>0.25r_{200}) of a sample of ten other nearby galaxy clusters observed with Suzaku for which robust measurements based on the Fe-K lines can be made. Across our sample the iron abundances are consistent with a constant value, ZFe=0.316±0.012Z_{\rm Fe}=0.316\pm0.012 Solar (χ2=28.85\chi^2=28.85 for 25 degrees of freedom). This is remarkably similar to the measurements for the Perseus cluster of ZFe=0.314±0.012Z_{\rm Fe}=0.314\pm0.012 Solar, using the Solar abundance scale of Asplund et al. (2009).Comment: accepted for publication in MNRA

    Witnessing the Growth of the Nearest Galaxy Cluster: Thermodynamics of the Virgo Cluster Outskirts

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    We present results from Suzaku Key Project observations of the Virgo Cluster, the nearest galaxy cluster to us, mapping its X-ray properties along four long `arms' extending beyond the virial radius. The entropy profiles along all four azimuths increase with radius, then level out beyond 0.5r2000.5r_{200}, while the average pressure at large radii exceeds Planck Sunyaev-Zel'dovich measurements. These results can be explained by enhanced gas density fluctuations (clumping) in the cluster's outskirts. Using a standard Navarro, Frenk and White (1997) model, we estimate a virial mass, radius, and concentration parameter of M200=1.05±0.02×1014M_{200}=1.05\pm0.02\times10^{14} M_\odot, r200=974.1±5.7r_{200}=974.1\pm5.7 kpc, and c=8.8±0.2c = 8.8 \pm0.2, respectively. The inferred cumulative baryon fraction exceeds the cosmic mean at rr200r\sim r_{200} along the major axis, suggesting enhanced gas clumping possibly sourced by a candidate large-scale structure filament along the north-south direction. The Suzaku data reveal a large-scale sloshing pattern, with two new cold fronts detected at radii of 233 kpc and 280 kpc along the western and southern arms, respectively. Two high-temperature regions are also identified 1 Mpc towards the south and 605 kpc towards the west of M87, likely representing shocks associated with the ongoing cluster growth. Although systematic uncertainties in measuring the metallicity for low temperature plasma remain, the data at large radii appear consistent with a uniform metal distribution on scales of 90×180\sim 90\times180 kpc and larger, providing additional support for the early chemical enrichment scenario driven by galactic winds at redshifts of 2-3.Comment: submitted to MNRA

    Lobster Eye X-ray optics for astrophysics: Recent status

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    X-ray optics in Lobster Eye arrangement represent promising complementary device to narrow field X-ray optics in common use. We present briefly recent status of design, developments, and tests of X-ray optics including Lobster Eye modules developed and tested within recent space project

    New Directions in the Study of Elites

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    http://deepblue.lib.umich.edu/bitstream/2027.42/50858/1/77.pd

    Parallelization of chip-based fluorescence immuno-assays with quantum-dot labelled beads

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    This paper presents an optical concept for the read-out of a parallel, bead-based fluorescence immunoassay conducted on a lab-on-a-disk platform. The reusable part of the modular setup comprises a detection unit featuring a single LED as light source, two emission-filters, and a color CCD-camera as standard components together with a spinning drive as actuation unit. The miniaturized lab-on-a-disk is devised as a disposable. In the read-out process of the parallel assay, beads are first identified by the color of incorporated quantum dots (QDs). Next, the reaction-specific fluorescence signal is quantified with FluoSpheres-labeled detection anti-bodies. To enable a fast and automated read-out, suitable algorithms have been implemented in this work. Based on this concept, we successfully demonstrated a Hepatitis-A assay on our disk-based lab-on-a-chip

    Outcome of patients admitted with acute coronary syndrome on palliative treatment: insights from the nationwide AMIS Plus Registry 1997-2014.

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    OBJECTIVE: Compliance with guidelines is increasingly used to benchmark the quality of hospital care, however, very little is known on patients admitted with acute coronary syndromes (ACS) and treated palliatively. This study aimed to evaluate the baseline characteristics and outcomes of these patients. DESIGN: Prospective cohort study. SETTING: Eighty-two Swiss hospitals enrolled patients from 1997 to 2014. PARTICIPANTS: All patients with ACS enrolled in the AMIS Plus registry (n=45,091) were analysed according to three treatment groups: palliative treatment, defined as use of aspirin and analgesics only and no reperfusion; conservative treatment, defined as any treatment including antithrombotics or anticoagulants, heparins, P2Y12 inhibitors, GPIIb/IIIa but no pharmacological or mechanical reperfusion; and reperfusion treatment (thrombolysis and/or percutaneous coronary intervention during initial hospitalisation). The primary outcome measure was in-hospital mortality and the secondary measure was 1-year mortality. RESULTS: Of the patients, 1485 (3.3%) were palliatively treated, 11,119 (24.7%) were conservatively treated and 32,487 (72.0%) underwent reperfusion therapy. In 1997, 6% of all patients were treated palliatively and this continuously decreased to 2% in 2013. Baseline characteristics of palliative patients differed in comparison with conservatively treated and reperfusion patients in age, gender and comorbidities (all p<0.001). These patients had more in-hospital complications such as postadmission onset of cardiogenic shock (15.6% vs 5.2%; p<0.001), stroke (1.8% vs 0.8%; p=0.001) and a higher in-hospital mortality (25.8% vs 5.6%; p<0.001).The subgroup of patients followed 1 year after discharge (n=8316) had a higher rate of reinfarction (9.2% vs 3.4%; p=0.003) and mortality (14.0% vs 3.5%; p<0.001). CONCLUSIONS: Patients with ACS treated palliatively were older, sicker, with more heart failure at admission and very high in-hospital mortality. While refraining from more active therapy may often constitute the most humane and appropriate approach, we think it is important to also evaluate these patients and include them in registries and outcome evaluations. CLINICAL TRIAL NUMBER: ClinicalTrials.gov Identifier: NCT01 305 785

    Proof-Pattern Recognition and Lemma Discovery in ACL2

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    We present a novel technique for combining statistical machine learning for proof-pattern recognition with symbolic methods for lemma discovery. The resulting tool, ACL2(ml), gathers proof statistics and uses statistical pattern-recognition to pre-processes data from libraries, and then suggests auxiliary lemmas in new proofs by analogy with already seen examples. This paper presents the implementation of ACL2(ml) alongside theoretical descriptions of the proof-pattern recognition and lemma discovery methods involved in it
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