742 research outputs found

    Acute safety, effectiveness, and real-world clinical usage of ultra-high density mapping for ablation of cardiac arrhythmias: results of the TRUE HD study

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    AIMS: The objective of this study was to verify acute safety, performance, and usage of a novel ultra-high density mapping system in patients undergoing ablation procedure in a real-world clinical setting. METHODS AND RESULTS: The TRUE HD study enrolled patients undergoing catheter ablation with mapping for all arrhythmias (excluding de novo atrial fibrillation) who were followed for 1 month. Safety was determined by collecting all serious adverse events and adverse events associated with the study devices. Performance was determined as the composite of: ability to map the arrhythmia/substrate, complete the ablation applications, arrhythmia termination (where applicable), and ablation validation. Use of mapping system in the ablation validation workflow was also evaluated. Among the 519 patients who underwent a complete (504) or attempted (15) procedure, 21 (4%) serious ablation-related complications were collected, with 3 (0.57%) potentially related to the mapping catheter. Four hundred and twenty treated patients resulted in a successful procedure confirmed by arrhythmia-specific validation techniques (83.3%; 95% confidence interval: 79.8-86.5%). A total of 1419 electroanatomical maps were created with a median acquisition time of 9:23 min per map. Of these, 372 maps in 222 (44%) patients were collected for ablation validation purposes. Following validation mapping, 162/222 (73%) patients required additional ablation. CONCLUSION: In the TRUE HD study mapping was associated with rates of acute success and complications consistent with previously published reports. Importantly, a low percentage of events (0.57%) was attributed to the mapping catheter. When performed, validation mapping was useful for identifying additional targets for ablation in the majority of patients

    Optical Trapping of an Ion

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    For several decades, ions have been trapped by radio frequency (RF) and neutral particles by optical fields. We implement the experimental proof-of-principle for trapping an ion in an optical dipole trap. While loading, initialization and final detection are performed in a RF trap, in between, this RF trap is completely disabled and substituted by the optical trap. The measured lifetime of milliseconds allows for hundreds of oscillations within the optical potential. It is mainly limited by heating due to photon scattering. In future experiments the lifetime may be increased by further detuning the laser and cooling the ion. We demonstrate the prerequisite to merge both trapping techniques in hybrid setups to the point of trapping ions and atoms in the same optical potential.Comment: 5 pages, 3 figure

    Dispersion relations in real and virtual Compton scattering

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    A unified presentation is given on the use of dispersion relations in the real and virtual Compton scattering processes off the nucleon. The way in which dispersion relations for Compton scattering amplitudes establish connections between low energy nucleon structure quantities, such as polarizabilities or anomalous magnetic moments, and the nucleon excitation spectrum is reviewed. We discuss various sum rules for forward real and virtual Compton scattering, such as the Gerasimov-Drell-Hearn sum rule and its generalizations, the Burkhardt-Cottingham sum rule, as well as sum rules for forward nucleon polarizabilities, and review their experimental status. Subsequently, we address the general case of real Compton scattering (RCS). Various types of dispersion relations for RCS are presented as tools for extracting nucleon polarizabilities from the RCS data. The information on nucleon polarizabilities gained in this way is reviewed and the nucleon structure information encoded in these quantities is discussed. The dispersion relation formalism is then extended to virtual Compton scattering (VCS). The information on generalized nucleon polarizabilities extracted from recent VCS experiments is described, along with its interpretation in nucleon structure models. As a summary, the physics content of the existing data is discussed and some perspectives for future theoretical and experimental activities in this field are presented.Comment: 120 pages, 42 figures, to appear in Phys. Re

    Macrodimers: ultralong range Rydberg molecules

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    We study long range interactions between two Rydberg atoms and predict the existence of ultralong range Rydberg dimers with equilibrium distances of many thousand Bohr radii. We calculate the dispersion coefficients C5C_{5}, C6C_{6} and C8C_{8} for two rubidium atoms in the same excited level npnp, and find that they scale like n8n^{8}, n11n^{11} and n15n^{15}, respectively. We show that for certain molecular symmetries, these coefficients lead to long range potential wells that can support molecular bound levels. Such macrodimers would be very sensitive to their environment, and could probe weak interactions. We suggest experiments to detect these macrodimers.Comment: 4 pages, submitted to PR

    CLEAR: The Gas-Phase Metallicity Gradients of Star-Forming Galaxies at 0.6 < z < 2.6

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    We report on the gas-phase metallicity gradients of a sample of 264 star-forming galaxies at 0.6 < z < 2.6, measured through deep near-infrared Hubble Space Telescope slitless spectroscopy. The observations include 12-orbit depth Hubble/WFC3 G102 grism spectra taken as a part of the CANDELS Lya Emission at Reionization (CLEAR) survey, and archival WFC3 G102+G141 grism spectra overlapping the CLEAR footprint. The majority of galaxies (84%) in this sample are consistent with a zero or slightly positive metallicity gradient across the full mass range probed (8.5 < log M_*/M_sun < 10.5). We measure the intrinsic population scatter of the metallicity gradients, and show that it increases with decreasing stellar mass---consistent with previous reports in the literature, but confirmed here with a much larger sample. To understand the physical mechanisms governing this scatter, we search for correlations between the observed gradient and various stellar population properties at fixed mass. However, we find no evidence for a correlation with the galaxy properties we consider---including star-formation rates, sizes, star-formation rate surface densities, and star-formation rates per gravitational potential energy. We use the observed weakness of these correlations to provide material constraints for predicted intrinsic correlations from theoretical models.Comment: 19 pages, 10 figures (v2: typo fixed in Figure 10 label); submitted to Ap

    Acute, fatal postoperative myocardial infarction after laparoscopic cholecystectomy in a cardiac patient -A case report-

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    This report presents the case of a 63-year-old man who had a myocardial infarction leading to coronary artery bypass graft 2 years earlier who subsequently underwent elective laparoscopic cholecystectomy. After an uneventful operation, the patient developed an acute postoperative myocardial infarction in the recovery room and died 19 days postoperatively. Anesthesiologists should be aware of the rare possibility of acute, fatal postoperative myocardial infarction and consider this complication when they perform the preoperative risk evaluation, anesthesia, and postoperative care for cardiac patients undergoing noncardiac surgery

    CLEAR: Paschen-β\beta Star Formation Rates and Dust Attenuation of Low Redshift Galaxies

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    We use \Pab\ (1282~nm) observations from the Hubble Space Telescope (\HST) G141 grism to study the star-formation and dust attenuation properties of a sample of 29 low-redshift (z<0.287z < 0.287) galaxies in the CANDELS Lyα\alpha Emission at Reionization (CLEAR) survey. We first compare the nebular attenuation from \Pab/\Ha with the stellar attenuation inferred from the spectral energy distribution, finding that the galaxies in our sample are consistent with an average ratio of the continuum attenuation to the nebular gas of 0.44, but with a large amount of excess scatter beyond the observational uncertainties. Much of this scatter is linked to a large variation between the nebular dust attenuation as measured by (space-based) \Pab to (ground-based) \Ha to that from (ground-based) \Ha/\Hb. This implies there are important differences between attenuation measured from grism-based / wide-aperture \Pab fluxes and the ground-based / slit-measured Balmer decrement. We next compare star-formation rates (SFRs) from \Pab to those from dust-corrected UV. We perform a survival analysis to infer a census of \Pab\ emission implied by both detections and non-detections. We find evidence that galaxies with lower stellar mass have more scatter in their ratio of \Pab\ to attenuation-corrected UV SFRs. When considering our \Pab\ detection limits, this observation supports the idea that lower mass galaxies experience "burstier" star-formation histories. Together, these results show that \Pab\ is a valuable tracer of a galaxy's SFR, probing different timescales of star-formation and potentially revealing star-formation that is otherwise missed by UV and optical tracers.Comment: 19 pages, 14 figures, 2 table

    Multiscale approach including microfibril scale to assess elastic constants of cortical bone based on neural network computation and homogenization method

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    The complexity and heterogeneity of bone tissue require a multiscale modelling to understand its mechanical behaviour and its remodelling mechanisms. In this paper, a novel multiscale hierarchical approach including microfibril scale based on hybrid neural network computation and homogenisation equations was developed to link nanoscopic and macroscopic scales to estimate the elastic properties of human cortical bone. The multiscale model is divided into three main phases: (i) in step 0, the elastic constants of collagen-water and mineral-water composites are calculated by averaging the upper and lower Hill bounds; (ii) in step 1, the elastic properties of the collagen microfibril are computed using a trained neural network simulation. Finite element (FE) calculation is performed at nanoscopic levels to provide a database to train an in-house neural network program; (iii) in steps 2 to 10 from fibril to continuum cortical bone tissue, homogenisation equations are used to perform the computation at the higher scales. The neural network outputs (elastic properties of the microfibril) are used as inputs for the homogenisation computation to determine the properties of mineralised collagen fibril. The mechanical and geometrical properties of bone constituents (mineral, collagen and cross-links) as well as the porosity were taken in consideration. This paper aims to predict analytically the effective elastic constants of cortical bone by modelling its elastic response at these different scales, ranging from the nanostructural to mesostructural levels. Our findings of the lowest scale's output were well integrated with the other higher levels and serve as inputs for the next higher scale modelling. Good agreement was obtained between our predicted results and literature data.Comment: 2

    CLEAR: High-Ionization [Ne V] λ{\lambda}3426 Emission-line Galaxies at 1.4<z<2.31.4 <z< 2.3

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    We analyze a sample of 25 [Ne V] λ\lambda3426 emission-line galaxies at 1.4<z<2.31.4<z<2.3 using Hubble Space Telescope/Wide Field Camera 3 G102 and G141 grism observations from the CANDELS Lyman-α\alpha Emission at Reionization (CLEAR) survey. [Ne V] emission probes extremely energetic photoionization (97.11-126.21 eV), and is often attributed to energetic radiation from active galactic nuclei (AGN), shocks from supernova, or an otherwise very hard ionizing spectrum from the stellar continuum. In this work, we use [Ne V] in conjunction with other rest-frame UV/optical emission lines ([O II] λλ\lambda\lambda3726,3729, [Ne III] λ\lambda3869, Hβ\beta, [O III] λλ\lambda\lambda4959,5007, Hα\alpha+[N II] λλ\lambda\lambda6548,6583, [S II] λλ\lambda\lambda6716,6731), deep (2--7 Ms) X-ray observations (from Chandra), and mid-infrared imaging (from Spitzer) to study the origin of this emission and to place constraints on the nature of the ionizing engine. The majority of the [Ne V]-detected galaxies have properties consistent with ionization from AGN. However, for our [Ne V]-selected sample, the X-ray luminosities are consistent with local (z0.1z\lesssim 0.1) X-ray-selected Seyferts, but the [Ne V] luminosities are more consistent with those from z1z\sim 1 X-ray-selected QSOs. The excess [Ne V] emission requires either reduced hard X-rays, or a \sim0.1 keV excess. We discuss possible origins of the apparent [Ne V] excess, which could be related to the ``soft (X-ray) excess'' observed in some QSOs and Seyferts, and/or be a consequence of a complex/anisotropic geometry for the narrow line region, combined with absorption from a warm, relativistic wind ejected from the accretion disk. We also consider implications for future studies of extreme high-ionization systems in the epoch of reionization (z6z \gtrsim 6) with JWST.Comment: 17 pages + 5 (appendix), 7 figures + 2(appendix
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