517 research outputs found

    Simply connected minimal symplectic 4-manifolds with signature less than - 1

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    For each pair (e,σ) of integers satisfying 2e + 3σ ≥ 0, σ ≤ - 2, and e + σ ≡0 (mod 4), with four exceptions, we construct a minimal, simply connected symplectic 4-manifold with Euler characteristic e and signature σ. We also produce simply connected, minimal symplectic 4-manifolds with signature zero (resp. signature-1) with Euler characteristic 4k (resp. 4k + 1) for all k ≥ 46 (resp. k ≥ 49). © European Mathematical Society 2010

    A Novel Compact Microwave Radiometric Sensor to Noninvasively Track Deep Tissue Thermal Profiles

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    Drawing from space technology to measure star temperature, we developed a noninvasive sensor to passively track thermal profiles in tissues well below the skin (\u3e5cm). Ultra-low noise amplifiers combined with ultralow-loss switches in the 1- 2GHz band produce a high sensitivity multiband microwave radiometer. Due to the complex multilayer anatomy of human head, multiple sensing bands are needed to reconstruct the temperature of deep brain tissue. This is achieved by using a digitally controlled filter bank. To study its accuracy, the sensor was calibrated and tested in a multilayer phantom model of the human head with differential scalp and brain temperatures. Results of phantom testing showed that calculated radiometric equivalent brain temperature agreed within 0.4°C of measured temperature when circulating homogenized brain phantom was lowered 10°C and returned to original temperature (37°C), while scalp was maintained constant over a 4.6-hour experiment. Feasibility of clinical monitoring was assessed in a pediatric patient during a hypothermic heart surgery. Over the 2-hour surgery, the radiometric sensor tracked within 1°C of rectal and nasopharynx temperatures, except during rapid cooldown and heatup periods when brain temperature deviated 2-4°C from slower responding core temperature surrogates. In summary, the sensor demonstrated long term stability and sensitivity sufficient for accurate monitoring of volume average brain temperatur

    The Stellar Populations of M33's Outer Regions IV: Inflow History and Chemical Evolution

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    We have modelled the observed color-magnitude diagram (CMD) at one location in M33's outskirts under the framework of a simple chemical evolution scenario which adopts instantaneous and delayed recycling for the nucleosynthetic products of Type II and Ia supernovae. In this scenario, interstellar gas forms stars at a rate modulated by the Kennicutt-Schmidt relation and gas outflow occurs at a rate proportional to the star formation rate (SFR). With this approach, we put broad constraints on the role of gas flows during this region's evolution and compare its [alpha/Fe] vs. [Fe/H] relation with that of other Local Group systems. We find that models with gas inflow are significantly better than the closed box model at reproducing the observed distribution of stars in the CMD. The best models have a majority of gas inflow taking place in the last 7 Gyr, and relatively little in the last 3 Gyr. These models predict most stars in this region to have [alpha/Fe] ratios lower than the bulk of the Milky Way's halo. The predictions for the present-day SFR, gas mass, and oxygen abundance compare favorably to independent empirical estimates. Our results paint a picture in which M33's outer disc formed from the protracted inflow of gas over several Gyr with at least half of the total inflow occurring since z ~ 1.Comment: 22 pages, 12 figures, accepted to MNRA

    Open Data and Digital Morphology

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    Over the past two decades, the development of methods for visualizing and analysing specimens digitally, in three and even four dimensions, has transformed the study of living and fossil organisms. However, the initial promise that the widespread application of such methods would facilitate access to the underlying digital data has not been fully achieved. The underlying datasets for many published studies are not readily or freely available, introducing a barrier to verification and reproducibility, and the reuse of data. There is no current agreement or policy on the amount and type of data that should be made available alongside studies that use, and in some cases are wholly reliant on, digital morphology. Here, we propose a set of recommendations for minimum standards and additional best practice for three-dimensional digital data publication, and review the issues around data storage, management and accessibility

    A low density of 0.8 g/cc for the Trojan binary asteroid 617 Patroclus

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    The Trojan population consists of two swarms of asteroids following the same orbit as Jupiter and located at the L4 and L5 Lagrange points of the Jupiter-Sun system (leading and following Jupiter by 60 degrees). The asteroid 617 Patroclus is the only known binary Trojan (Merline et al. 2001). The orbit of this double system was hitherto unknown. Here we report that the components, separated by 680 km, move around the system centre of mass, describing roughly a circular orbit. Using the orbital parameters, combined with thermal measurements to estimate the size of the components, we derive a very low density of 0.8 g/cc. The components of Patroclus are therefore very porous or composed mostly of water ice, suggesting that they could have been formed in the outer part of the solar system.Comment: 10 pages, 3 figures, 1 tabl

    Pre-hospital management protocols and perceived difficulty in diagnosing acute heart failure

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    Aim To illustrate the pre-hospital management arsenals and protocols in different EMS units, and to estimate the perceived difficulty of diagnosing suspected acute heart failure (AHF) compared with other common pre-hospital conditions. Methods and results A multinational survey included 104 emergency medical service (EMS) regions from 18 countries. Diagnostic and therapeutic arsenals related to AHF management were reported for each type of EMS unit. The prevalence and contents of management protocols for common medical conditions treated pre-hospitally was collected. The perceived difficulty of diagnosing AHF and other medical conditions by emergency medical dispatchers and EMS personnel was interrogated. Ultrasound devices and point-of-care testing were available in advanced life support and helicopter EMS units in fewer than 25% of EMS regions. AHF protocols were present in 80.8% of regions. Protocols for ST-elevation myocardial infarction, chest pain, and dyspnoea were present in 95.2, 80.8, and 76.0% of EMS regions, respectively. Protocolized diagnostic actions for AHF management included 12-lead electrocardiogram (92.1% of regions), ultrasound examination (16.0%), and point-of-care testings for troponin and BNP (6.0 and 3.5%). Therapeutic actions included supplementary oxygen (93.2%), non-invasive ventilation (80.7%), intravenous furosemide, opiates, nitroglycerine (69.0, 68.6, and 57.0%), and intubation 71.5%. Diagnosing suspected AHF was considered easy to moderate by EMS personnel and moderate to difficult by emergency medical dispatchers (without significant differences between de novo and decompensated heart failure). In both settings, diagnosis of suspected AHF was considered easier than pulmonary embolism and more difficult than ST-elevation myocardial infarction, asthma, and stroke. Conclusions The prevalence of AHF protocols is rather high but the contents seem to vary. Difficulty of diagnosing suspected AHF seems to be moderate compared with other pre-hospital conditions

    D-meson semileptonic decays to pseudoscalars from four-flavor lattice QCD

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    We present lattice-QCD calculations of the hadronic form factors for the semileptonic decays D→πℓνD\to\pi\ell\nu, D→KℓνD\to K\ell\nu, and Ds→KℓνD_s\to K\ell\nu. Our calculation uses the highly improved staggered quark (HISQ) action for all valence and sea quarks and includes Nf=2+1+1N_f=2+1+1 MILC ensembles with lattice spacings ranging from a≈0.12a\approx0.12 fm down to 0.0420.042 fm. At most lattice spacings, an ensemble with physical-mass light quarks is included. The HISQ action allows all the quarks to be treated with the same relativistic light-quark action, allowing for nonperturbative renormalization using partial conservation of the vector current. We combine our results with experimental measurements of the differential decay rates to determine ∣Vcd∣D→π=0.2238(11)Expt(15)QCD(04)EW(02)SIB[22]QED|V_{cd}|^{D\to\pi}=0.2238(11)^{\rm Expt}(15)^{\rm QCD}(04)^{\rm EW}(02)^{\rm SIB}[22]^{\rm QED} and ∣Vcs∣D→K=0.9589(23)Expt(40)QCD(15)EW(05)SIB[95]QED|V_{cs}|^{D\to K}=0.9589(23)^{\rm Expt}(40)^{\rm QCD}(15)^{\rm EW}(05)^{\rm SIB}[95]^{\rm QED} This result for ∣Vcd∣|V_{cd}| is the most precise to date, with a lattice-QCD error that is, for the first time for the semileptonic extraction, at the same level as the experimental error. Using recent measurements from BES III, we also give the first-ever determination of ∣Vcd∣Ds→K=0.258(15)Expt(01)QCD[03]QED|V_{cd}|^{D_s\to K}=0.258(15)^{\rm Expt}(01)^{\rm QCD}[03]^{\rm QED} from Ds→KℓνD_s\to K \ell\nu. Our results also furnish new Standard Model calculations of the lepton flavor universality ratios RD→π=0.98671(17)QCD[500]QEDR^{D\to\pi}=0.98671(17)^{\rm QCD}[500]^{\rm QED}, RD→K=0.97606(16)QCD[500]QEDR^{D\to K}=0.97606(16)^{\rm QCD}[500]^{\rm QED}, and RDs→K=0.98099(10)QCD[500]QEDR^{D_s\to K}=0.98099(10)^{\rm QCD}[500]^{\rm QED}, which are consistent within 2σ2\sigma with experimental measurements. Our extractions of ∣Vcd∣|V_{cd}| and ∣Vcs∣|V_{cs}|, when combined with a value for ∣Vcb∣|V_{cb}|, provide the most precise test of second-row CKM unitarity, finding agreement with unitarity at the level of one standard deviation.Comment: 92 page
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