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
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
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
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
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 ,
and for two rubidium atoms in the same excited level , and find
that they scale like , and , 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
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
Quantum Corrections to Baryon Properties in Chiral Soliton Models
We present a procedure to calculate 1-loop graphs in the soliton sector of
chiral Lagrangians and use it to calculate quantum corrections to certain
baryon observables in Skyrme-type models. Results generally show an improvement
over the values obtained in tree approximation except for the case of the axial
coupling g_A.Comment: Chapters on magnetic polarizabilities and e.m. properties of Delta
isobar added, 90 pages, Latex, 9 Postscript figure
Acute, fatal postoperative myocardial infarction after laparoscopic cholecystectomy in a cardiac patient -A case report-
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- Star Formation Rates and Dust Attenuation of Low Redshift Galaxies
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 () galaxies in the CANDELS Ly
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
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] 3426 Emission-line Galaxies at
We analyze a sample of 25 [Ne V] 3426 emission-line galaxies at
using Hubble Space Telescope/Wide Field Camera 3 G102 and G141
grism observations from the CANDELS Lyman- 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]
3726,3729, [Ne III] 3869, H, [O III]
4959,5007, H+[N II] 6548,6583, [S II]
6716,6731), 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 () X-ray-selected Seyferts, but the [Ne V]
luminosities are more consistent with those from X-ray-selected QSOs.
The excess [Ne V] emission requires either reduced hard X-rays, or a 0.1
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 () with JWST.Comment: 17 pages + 5 (appendix), 7 figures + 2(appendix
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