121 research outputs found
The Evolution of Ideology, Fairness and Redistribution
Ideas about what is "fair" above and beyond the individual's position in the income ladder influence preferences for redistribution. We study the dynamic evolution of different economies in which redistributive policies, perceptions of fairness, inequality and growth are jointly determined. We show how including fairness explains various observed correlations between inequality, redistribution and growth. We also show how different beliefs about fairness can keep two otherwise identical countries in different development paths for a very long time.
Minimal fluoroscopic approaches and factors associated with radiation dose when high-definition mapping is used for supraventricular tachycardia ablation: insight from the CHARISMA registry
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Limited data exist on factors associated with radiation exposure during ablation procedures when a high definition mapping technology is used.
Purpose
To report factors associated with radiation exposure and data on feasibility and safety of a minimal fluoroscopic approach using the Rhythmia mapping system in supraventricular tachycardia (SVT) ablation procedures.
Methods
Consecutive patients indicated for arrhythmia ablation were enrolled in the CHARISMA study at 12 centers. We included in this analysis consecutive right-side procedures performed through a minimal fluoroscopy approach with the Rhythmia mapping system were analyzed. A 3D geometry of chambers of interest was reconstructed on the basis of the electroanatomic information taken from the mapping system. Fluoroscopy was used only if deemed necessary. The effective dose (ED) was calculated using accepted formula. For our purpose high dose exposure was defined as an ED greater than the median value of ED of the population exposed to radiation.
Results
This analysis included 325 patients (mean age = 56 ± 17 years, 57% male) undergoing SVT procedures (152 AVNRT, 116 AFL, 41 AP and 16 AT). During the study, 27481 seconds of fluoroscopy was used (84.6 ± 224 seconds per procedure), resulting in a mean equivalent ED of 1.1 ± 3.7 mSv per patient. The mean reconstructed RA volume was 99 ± 54 ml in a mean mapping time of 12.2 ± 7 min. The mean number of radiofrequency ablations (RFC) to terminate each arrhythmia was 9.4 ± 9 (mean RFC delivery time equal to 6.7 ± 6 min). 192 procedures (59.1%) were completed without any use of fluoroscopy; during the remaining 133 procedures (39.9%), 206.6 ± 313.4 seconds of fluoroscopy was used (median ED = 1.2 mSv). In a minority of the cases (n = 25, 7.7%) the fluoroscopy time was higher than 5 minutes (median ED = 6.5 mSv), whereas radiologic exposure time greater than 1 minute occurred in ninety cases (27.7%, median ED = 2.1 mSv). On multivariate logistic analysis adjusted for baseline confounders the RFC application time (OR = 1.0014, 95%CI: 1.0007 to 1.0022; p = 0.0001) was independently associated to an ED greater than 1.2 mSv, whereas female gender had an inverse association (0.54, 0.29 to 0.98; p = 0.0435). Acute success was reached in 97.8% of the cases. During a mean of 290.7 ± 169.6 days follow-up, no major adverse events related to the procedure were reported. Overall, the recurrence rate of the primary arrhythmia during follow-up was 2.5%.
Conclusions
In our experience, arrhythmias ablation through minimal fluoroscopy approach with the use of a novel ablation technology is safe, feasible, and effective in common right atrial arrhythmias. High-dose exposure occurred in a very limited number of cases, without any reduction of the safety and acute and long-term effectiveness profile
Orbital obliquity of the young planet TOI-5398 b and the evolutionary history of the system
Multi-planet systems exhibit remarkable architectural diversity. However, short-period giant planets are typically isolated. Compact systems like TOI-5398, with an outer close-orbit giant and an inner small-size planet, are rare among systems containing short-period giants. TOI-5398's unusual architecture coupled with its young age (650 +/- 150 Myr) make it a promising system for measuring the original obliquity between the orbital axis of the giant and the stellar spin axis in order to gain insight into its formation and orbital migration. We collected in-transit (plus suitable off-transit) observations of TOI-5398 b with HARPS-N at TNG on March 25, 2023, obtaining high-precision radial velocity time series that allowed us to measure the Rossiter-McLaughlin (RM) effect. By modelling the RM effect, we obtained a sky-projected obliquity of lambda = 3.0(-4.2)(+6.8) deg for TOI-5398 b, consistent with the planet being aligned. With knowledge of the stellar rotation period, we estimated the true 3D obliquity, finding psi = (13.2 +/- 8.2) deg. Based on theoretical considerations, the orientation we measure is unaffected by tidal effects, offering a direct diagnostic for understanding the formation path of this planetary system. The orbital characteristics of TOI-5398, with its compact architecture, eccentricity consistent with circular orbits, and hints of orbital alignment, appear more compatible with the disc-driven migration scenario. TOI-5398, with its relative youth (compared with similar compact systems) and exceptional suitability for transmission spectroscopy studies, presents an outstanding opportunity to establish a benchmark for exploring the disc-driven migration model
The GAPS Programme at TNG. LIII. New insights on the peculiar XO-2 system
Planets in binary systems are a fascinating and yet poorly understood
phenomenon. Since there are only a few known large-separation systems in which
both components host planets, characterizing them is a key target for planetary
science. In this paper, we aim to carry out an exhaustive analysis of the
interesting XO-2 system, where one component appears to be a system with only
one planet, while the other has at least three planets. Over the last 9 years,
we have collected 39 spectra of XO-2N and 106 spectra of XO-2S with the High
Accuracy Radial velocity Planet Searcher for the Northern emisphere (HARPS-N)
in the framework of the Global Architecture of Planetary Systems project, from
which we derived precise radial velocity and activity indicator measurements.
Additional spectroscopic data from the High Resolution Echelle Spectrometer and
from the High Dispersion Spectrograph, and the older HARPS-N data presented in
previous papers, have also been used to increase the total time span. We also
used photometric data from TESS to search for potential transits that have not
been detected yet. For our analysis, we mainly used PyORBIT, an advanced Python
tool for the Bayesian analysis of RVs, activity indicators, and light curves.
We found evidence for an additional long-period planet around XO-2S and
characterized the activity cycle likely responsible for the long-term RV trend
noticed for XO-2N. The new candidate is an example of a Jovian analog with
M, au, and . We also analyzed the
stability and detection limits to get some hints about the possible presence of
additional planets. Our results show that the planetary system of XO-2S is at
least one order of magnitude more massive than that of XO-2N. The implications
of these findings for the interpretation of the previously known abundance
difference between components are also discussed
Role of B diffusion in the interfacial Dzyaloshinskii-Moriya interaction in Ta / Co₂₀ Fe₆₀B₂₀/MgO nanowires
We report on current-induced domain wall motion in Ta/Co20Fe60B20/MgO nanowires. Domain walls are observed to move against the electron flow when no magnetic field is applied, while a field along the nanowires strongly affects the domain wall motion velocity. A symmetric effect is observed for up-down and down-up domain walls. This indicates the presence of right-handed domain walls, due to a Dzyaloshinskii-Moriya interaction (DMI) with a DMI coefficient D=+0.06mJ/m2. The positive DMI coefficient is interpreted to be a consequence of B diffusion into the Ta buffer layer during annealing, which was observed by chemical depth profiling measurements. The experimental results are compared to one-dimensional model simulations including the effects of pinning. This modeling allows us to reproduce the experimental outcomes and reliably extract a spin-Hall angle θSH=-0.11 for Ta in the nanowires, showing the importance of an analysis that goes beyond the model for perfect nanowires
The GAPS programme at TNG: XLIII. A massive brown dwarf orbiting the active M dwarf TOI-5375
Context. Massive substellar companions orbiting active low-mass stars are rare. They, however, offer an excellent opportunity to study the main mechanisms involved in the formation and evolution of substellar objects.
Aims: We aim to unravel the physical nature of the transit signal observed by the TESS space mission on the active M dwarf TOI-5375.
Methods: We analysed the available TESS photometric data as well as high-resolution (R ~ 115 000) HARPS-N spectra. We combined these data to characterise the star TOI-5375 and to disentangle signals related to stellar activity from the companion transit signal in the light-curve data. We ran a Markov chain Monte Carlo analysis to derive the orbital solution and applied state-of-the-art Gaussian process regression to deal with the stellar activity signal.
Results: We reveal the presence of a companion in the boundary between the brown dwarfs and the very-low-mass stars orbiting around the star TOI-5375. The best-fit model corresponds to a companion with an orbital period of 1.721564 ± 10−6 d, a mass of 77 ± 8 MJ, and a radius of 0.99 ± 0.16 RJ.
Conclusions: We derive a rotation period for the host star of 1.9692 ± 0.0004 d, and we conclude that the star is very close to synchronising its rotation with the orbital period of the companion
The GAPS programme at TNG XLV. A massive brown dwarf orbiting the active M dwarf TOI-5375
Context. Massive substellar companions orbiting active low-mass stars are
rare. They, however, offer an excellent opportunity to study the main
mechanisms involved in the formation and evolution of substellar objects. Aims.
We aim to unravel the physical nature of the transit signal observed by the
TESS space mission on the active M dwarf TOI-5375. Methods. We analysed the
available TESS photometric data as well as high-resolution (R 115000)
HARPS-N spectra. We combined these data to characterise the star TOI-5375 and
to disentangle signals related to stellar activity from the companion transit
signal in the light-curve data. We ran an MCMC analysis to derive the orbital
solution and apply state-of-the-art Gaussian process regression to deal with
the stellar activity signal. Results. We reveal the presence of a companion in
the brown dwarf / very-low-mass star boundary orbiting around the star
TOI-5375. The best-fit model corresponds to a companion with an orbital period
of 1.721564 10 d, a mass of 77 8 and a
radius of 0.99 0.16 . We derive a rotation period for the host
star of 1.9692 0.0004 d, and we conclude that the star is very close to
synchronising its rotation with the orbital period of the companion.Comment: Submitted to Astronomy & Astrophysics (under review
The GAPS Programme at TNG : LIV. A He I survey of close-in giant planets hosted by M-K dwarf stars with GIANO-B
Context. Atmospheric escape plays a fundamental role in shaping the properties of exoplanets. The metastable near-infrared (nIR) helium triplet at 1083.3 nm (He I) is a powerful proxy of extended and evaporating atmospheres.
Aims: We used the GIARPS (GIANO-B + HARPS-N) observing mode of the Telescopio Nazionale Galileo to search for He I absorption in the upper atmospheres of five close-in giant planets hosted by the K and M dwarf stars of our sample, namely WASP-69 b, WASP-107 b, HAT-P-11 b, GJ 436 b, and GJ 3470 b.
Methods: We focused our analysis on the nIR He I triplet, performing high-resolution transmission spectroscopy by comparing the in-transit and out-of-transit observations. In instances where nightly variability in the He I absorption signal was identified, we investigated the potential influence of stellar magnetic activity on the planetary absorption signal by searching for variations in the Hα transmission spectrum.
Results: We spectrally resolve the He I triplet and confirm the published detections for WASP-69 b (3.91 ± 0.22%, 17.6σ), WASP-107 b (8.17−0.76+0.80%, 10.5σ), HAT-P-11 b (1.36 ± 0.17%, 8.0σ), and GJ 3470 b (1.75−0.36+0.39%, 4.7σ). We do not find evidence of extra absorption for GJ 436 b. We observe night-to-night variations in the He I absorption signal for WASP-69 b, associated with variability in Hα, which likely indicates the influence of pseudo-signals related to stellar activity. Additionally, we find that the He I signal of GJ 3470 b originates from a single transit observation, thereby corroborating the discrepancies found in the existing literature. An inspection of the Hα line reveals an absorption signal during the same transit event.
Conclusions: By combining our findings with previous analyses of GIANO-B He I measurements of planets orbiting K dwarfs, we explore potential trends with planetary and stellar parameters that are thought to affect the absorption of metastable He I. Our analysis is unable to identify clear patterns, thus emphasising the necessity for additional measurements and the exploration of potential additional parameters that may be important in controlling He I absorption in planetary upper atmospheres
The GAPS Programme at TNG : XLVII. A conundrum resolved: HIP 66074b/Gaia-3b characterised as a massive giant planet on a quasi-face-on and extremely elongated orbit
The nearby mid-K dwarf HIP 66074 was recently identified as host to a candidate super-Jupiter companion on a similar to 300 day, almost edge-on, orbit, based on Gaia Data Release 3 (DR3) astrometry. Initial attempts at confirming the planetary nature of the signal based on publicly available radial-velocity (RV) observations uncovered an intriguing conundrum: the inferred RV semi-amplitude appears to be a factor of 15 smaller than the one predicted based on the Gaia solution (corresponding to a 7-M-Jup companion on a close to edge-on orbit). We present the results of intensive RV monitoring of HIP 66074 with the HARPS-N spectrograph. We detected the companion at the Gaia period, but with an extremely eccentric orbit (e = 0:948 +/- 0:004), a semi-amplitude K = 93.9(-7.0)(+9.4) m s(-1), and a minimum mass mb sin i(b) = 0.79 +/- 0.05 M-Jup. We used detailed simulations of Gaia astrometry with the DR3 time-span to show that the conundrum can be fully resolved by taking into account the combination of the initially sub-optimal RV sampling and systematic biases in the Gaia astrometric solution, which include an underestimation of the eccentricity and incorrect identification of orbital inclination, which has turned out to correspond to a close to face-on configuration (i less than or similar to 13 degrees). With an estimated mass in the approximate range of 3-7 M-Jup, we find that HIP 66074b (equivalent to Gaia-3b) is the first exoplanet candidate astrometrically detected by Gaia to be successfully confirmed based on RV follow-up observations
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