Fusing Continuous-valued Medical Labels using a Bayesian Model

With the rapid increase in volume of time series medical data available through wearable devices, there is a need to employ automated algorithms to label data. Examples of labels include interventions, changes in activity (e.g. sleep) and changes in physiology (e.g. arrhythmias). However, automated algorithms tend to be unreliable resulting in lower quality care. Expert annotations are scarce, expensive, and prone to significant inter- and intra-observer variance. To address these problems, a Bayesian Continuous-valued Label Aggregator(BCLA) is proposed to provide a reliable estimation of label aggregation while accurately infer the precision and bias of each algorithm. The BCLA was applied to QT interval (pro-arrhythmic indicator) estimation from the electrocardiogram using labels from the 2006 PhysioNet/Computing in Cardiology Challenge database. It was compared to the mean, median, and a previously proposed Expectation Maximization (EM) label aggregation approaches. While accurately predicting each labelling algorithm's bias and precision, the root-mean-square error of the BCLA was 11.78$\pm$0.63ms, significantly outperforming the best Challenge entry (15.37$\pm$2.13ms) as well as the EM, mean, and median voting strategies (14.76$\pm$0.52ms, 17.61$\pm$0.55ms, and 14.43$\pm$0.57ms respectively with $p<0.0001$)

Hard - X-rays selected Active Galactic Nuclei. I. A radio view at high-frequencies

A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High frequency radio observations can target the nuclear contribution of smaller emitting regions and are less affected by absorption. We present JVLA 22 and 45 GHz observations of 16 nearby (0.003$\le$z$\le$0.3) hard - X-rays selected AGN at the (sub)-kpc scale with tens uJy beam$^{-1}$ sensitivity. We detected 15/16 sources, with flux densities ranging from hundreds uJy beam$^{-1}$ to tens Jy (specific luminosities from $\sim$10$^{20}$ to $\sim$10$^{25}\,W\,Hz^{-1}$ at 22 GHz). All detected sources host a compact core, with 8 being core-dominated at either frequencies, the others exhibiting also extended structures. Spectral indices range from steep to flat/inverted. We interpret this evidence as either due to a core+jet system (6/15), a core accompanied by surrounding star formation (1/15), to a jet oriented close to the line of sight (3/15), to emission from a corona or the base of a jet (1/15), although there might be degeneracies between different processes. Four sources require more data to shed light on their nature. We conclude that, at these frequencies, extended, optically-thin components are present together with the flat-spectrum core. The ${L_R}/{L_X}\sim10^{-5}$ relation is roughly followed, indicating a possible contribution to radio emission from a hot corona. A weakly significant correlation between radio core (22 and 45 GHz) and X-rays luminosities is discussed in the light of an accretion-ejection framework.Comment: Accepted for publication on MNRA

Absorption spectra of Fe L-lines in Seyfert 1 galaxies

Absorption L-lines of iron ions are observed, in absorption, in spectra of Seyfert 1 galaxies by the new generation of X-ray satellites: Chandra (NASA) and XMM-Newton (ESA). Lines associated to Fe23+ to Fe17+ are well resolved. Whereas, those corresponding to Fe16+ to Fe6+ are unresolved. Forbidden transitions of the Fe16+ to Fe6+ ions were previously observed, for the same objects, in the visible and infra-red regions, showing that the plasma had a low density. To interpret X-ray, visible and infra-red data, astrophysical models assume an extended absorbing medium of very low density surrounding an intense X-ray source. We have calculated atomic data (wavelengths, radiative and autoionization rates) for n=2 to n'=3-4 transitions and used them to construct refined synthetic spectra of the unresolved part of the L-line spectra.Comment: 17 pages, 5 figures, Journal of Quantitative Spectroscopy and Radiative Transfer, in pres

Dielectronic Recombination (via N=2 --> N'=2 Core Excitations) and Radiative Recombination of Fe XX: Laboratory Measurements and Theoretical Calculations

We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N=2 --> N'=2 (Delta_N=0) core excitations. We have also calculated the DR resonance strengths and energies using AUTOSTRUCTURE, HULLAC, MCDF, and R-matrix methods, four different state-of-the-art theoretical techniques. On average the theoretical resonance strengths agree to within <~10% with experiment. However, the 1 sigma standard deviation for the ratios of the theoretical-to-experimental resonance strengths is >~30% which is significantly larger than the estimated relative experimental uncertainty of <~10%. This suggests that similar errors exist in the calculated level populations and line emission spectrum of the recombined ion. We confirm that theoretical methods based on inverse-photoionization calculations (e.g., undamped R-matrix methods) will severely overestimate the strength of the DR process unless they include the effects of radiation damping. We also find that the coupling between the DR and radiative recombination (RR) channels is small. We have used our experimental and theoretical results to produce Maxwellian-averaged rate coefficients for Delta_N=0 DR of Fe XX. For kT>~1 eV, which includes the predicted formation temperatures for Fe XX in an optically thin, low-density photoionized plasma with cosmic abundances, our experimental and theoretical results are in good agreement. We have also used our R-matrix results, topped off using AUTOSTRUCTURE for RR into J>=25 levels, to calculate the rate coefficient for RR of Fe XX. Our RR results are in good agreement with previously published calculations.Comment: To be published in ApJS. 65 pages with 4 tables and lots of figure

The radio emission in radio-quiet quasars: the VLBA perspective

The origin of the radio emission in radio-quiet quasars (RQQ) is not established yet. We present new VLBA observations at 1.6 and 4.9 GHz of ten RQQ (nine detected), which together with published earlier observations of eight RQQ (five detected), forms a representative sample of 18 RQQ drawn from the Palomar-Green sample of low z (< 0.5) AGN. The spectral slope of the integrated emission extends from very steep (alpha < -1.98) to strongly inverted (alpha = +2.18), and the slopes of nine of the 14 objects are flat (alpha > -0.5). Most objects have an unresolved flat-spectrum core, which coincides with the optical Gaia position. The extended emission is generally steep-spectrum, has a low brightness temperature (< 10^7 K), and is displaced from the optical core (the Gaia position) by ~ 5-100 pc. The VLBA core flux is tightly correlated with the X-ray flux, and follows a radio to X-ray luminosity relation of log L_R/L_X = -6, for all objects with a black hole mass log M_BH/M_Sun < 8.5. The flatness of the core emission implies a compact source size (< 0.1 pc), which likely originates from the accretion disk corona. The mas-scale extended emission is optically thin and of clumpy structure, and is likely produced by an outflow from the center. Radio observations at higher frequencies can further test the accretion disk coronal emission interpretation for the core emission in RQQ.Comment: Accepted for publication in MNRA

A genetic contribution from the Far East into Ashkenazi Jews via the ancient Silk Road

Contemporary Jews retain a genetic imprint from their Near Eastern ancestry, but obtained substantial genetic components from their neighboring populations during their history. Whether they received any genetic contribution from the Far East remains unknown, but frequent communication with the Chinese has been observed since the Silk Road period. To address this issue, mitochondrial DNA (mtDNA) variation from 55,595 Eurasians are analyzed. The existence of some eastern Eurasian haplotypes in eastern Ashkenazi Jews supports an East Asian genetic contribution, likely from Chinese. Further evidence indicates that this connection can be attributed to a gene flow event that occurred less than 1.4 kilo-years ago (kya), which falls within the time frame of the Silk Road scenario and fits well with historical records and archaeological discoveries. This observed genetic contribution from Chinese to Ashkenazi Jews demonstrates that the historical exchange between Ashkenazim and the Far East was not confined to the cultural sphere but also extended to an exchange of genes