HD 100453AB is a 10 2 Myr old binary whose protoplanetary disk was recently revealed to host a global two-armed spiral structure. Given the relatively small projected separation of the binary (1 05, ...or ∼108 au), gravitational perturbations by the binary seemed to be a likely driving force behind the formation of the spiral arms. However, the orbit of these stars remained poorly understood, which prevented a proper treatment of the dynamical influence of the companion on the disk. We observed HD 100453AB between 2015 and 2017, utilizing extreme adaptive optics systems on the Very Large Telescope and the Magellan Clay Telescope. We combined the astrometry from these observations with published data to constrain the parameters of the binary's orbit to a = 1 06 0 09, e = 0.17 0.07, and i = 32 5 6 5. We utilized publicly available ALMA 12CO data to constrain the inclination of the disk, , which is relatively coplanar with the orbit of the companion and consistent with previous estimates from scattered light images. Finally, we input these constraints into hydrodynamic and radiative transfer simulations to model the structural evolution of the disk. We find that the spiral structure and truncation of the circumprimary disk in HD 100453 are consistent with a companion-driven origin. Furthermore, we find that the primary star's rotation, its outer disk, and the companion exhibit roughly the same direction of angular momentum, and thus the system likely formed from the same parent body of material.
The assessment of systolic dyssynchrony by echocardiography is useful in predicting a favorable response to cardiac resynchronization therapy (CRT). Tissue Doppler velocity and tissue Doppler ...longitudinal strain have been suggested for this purpose. This study compared parameters of systolic dyssynchrony derived from these 2 imaging modalities for their predictive values of CRT response. Two hundred fifty-six patients from 3 different centers who received CRT were followed for 6 ± 3 months. Parameters of systolic dyssynchrony based on tissue Doppler velocity and strain imaging were assessed for the prediction of left ventricular (LV) reverse remodeling (reduction of LV end-systolic volume ≥15%). These included time to peak systolic velocity (or peak strain) of 12 LV segments to calculate the SD (Ts-SD or Tε-SD), maximal difference in delay (Ts-Diff or Tε-Diff), and opposite wall delay (Ts-OW or Tε-OW). The septal-to-lateral delay (Ts-Sep-Lat or Tε-Sep-Lat) was also measured. LV reverse remodeling, defined as improvement in end-systolic volume ≥15%, was observed in 141 patients (55%). All 4 tissue velocity parameters predicted LV reverse remodeling, and the areas under the receiver-operating characteristic curves were 0.86, 0.85, 0.84, and 0.79 for Ts-SD, Ts-Diff, Ts-OW, and Ts-Sep-Lat, respectively (all p <0.001). The cut-off values derived from receiver-operating characteristic curve analysis were 33 ms for Ts-SD, 100 ms for Ts-Diff, 90 ms for Ts-OW, and 60 ms for Ts-Sep-Lat, and their sensitivities were 93%, 92%, 81%, and 70%, with specificities of 78%, 68%, 80%, and 76%, respectively. In contrast, none of the longitudinal strain parameters predicted LV reverse remodeling. The areas under the receiver-operating characteristic curves ranged from 0.49 to 0.53 (all p = NS). The same conclusions were obtained in subgroup analyses of QRS duration (120 to 150 vs >150 ms) and ischemic or nonischemic cause of heart failure. In conclusion, parameters of tissue Doppler longitudinal velocity, but not longitudinal strain, predicted LV reverse remodeling after CRT.
Planetary Torque in 3D Isentropic Disks Fung, Jeffrey; Masset, Frédéric; Lega, Elena ...
The Astronomical journal,
03/2017, Letnik:
153, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Planetary migration is inherently a three-dimensional (3D) problem, because Earth-size planetary cores are deeply embedded in protoplanetary disks. Simulations of these 3D disks remain challenging ...due to the steep resolution requirements. Using two different hydrodynamics codes, FARGO3D and PEnGUIn, we simulate disk-planet interaction for a one to five Earth-mass planet embedded in an isentropic disk. We measure the torque on the planet and ensure that the measurements are converged both in resolution and between the two codes. We find that the torque is independent of the smoothing length of the planet's potential (rs), and that it has a weak dependence on the adiabatic index of the gaseous disk (γ). The torque values correspond to an inward migration rate qualitatively similar to previous linear calculations. We perform additional simulations with explicit radiative transfer using FARGOCA, and again find agreement between 3D simulations and existing torque formulae. We also present the flow pattern around the planets that show active flow is present within the planet's Hill sphere, and meridional vortices are shed downstream. The vertical flow speed near the planet is faster for a smaller rs or γ, up to supersonic speeds for the smallest rs and γ in our study.
Aims
Right ventricular apex (RVA) pacing may have deleterious effects on left ventricular (LV) systolic function, but its impact on LV diastolic function has not been explored.
Methods and results
...Ninety-seven patients with sinus node dysfunction and ejection fraction (EF) ≥50% with permanent RVA pacing were randomly programmed to V-sense and V-pace modes and examined by echocardiography. Tissue Doppler imaging was employed to assess myocardial systolic velocity (S′) and early diastolic velocity (E′) at the mitral annulus. Systolic dyssynchrony was assessed using 12 LV segmental model (Ts-SD). Switching from V-sense to V-pace resulted in the worsening of both diastolic and systolic functions as shown by the decreased EF, reduced mean E′ and S′ velocities, as well as increase in LV volume and Ts-SD (all P< 0.001). Reduction of mean E′ and S′ of ≥1 cm/s occurred in 35 (36%) and 45 (46%) patients, respectively. In pre-defined subgroup analysis, only patients with pre-existing LV diastolic dysfunction had a significant reduction of mean E′ and S′ (both P< 0.001) even after age adjustment. Multivariate logistic regression analysis showed that independent factors for the reduction of mean E′ ≥ 1 cm/s or mean S′ ≥ 1 cm/s at V-pace were pre-existing LV diastolic dysfunction odds ratio (OR): 4.735, P= 0.007 for E′; OR: 3.307, P= 0.022 for S′ and systolic dyssynchrony at V-pace (OR: 5.459, P= 0.007 for E′; OR: 2.725, P= 0.035 for S′).
Conclusion
In patients with preserved EF, RVA pacing is associated with the deterioration of both LV diastolic and systolic functions, which is particularly obvious in those with pre-existing LV diastolic dysfunction and V-pace-induced systolic dyssynchrony.
Abstract Aims The purpose of this study was to assess the feasibility of measuring left atrial dysfunction with tissue Doppler imaging derived strain rate and to explore its role in predicting the ...maintenance of sinus rhythm after cardioversion for atrial fibrillation. Methods and results Strain rate (SR) and tissue Doppler imaging (TDI) were performed with offline analysis of the basal left atrial wall (LA). SR detected a systolic (Ssr) and early diastolic (Esr) deformation induced by ventricular motion. LA dimensions and volume were measured. Left atrial appendage emptying (LAA_EV) and filling (LAA_FV) velocities were also obtained by transesophageal echocardiography. 27 healthy age-matched controls and 42 patients with AF before cardioversion were studied. Patients were grouped into (1): those who remained in sinus rhythm (group S, n = 12) and (2) those who either failed cardioversion or reverted to AF within 4 weeks (group F, n = 30). LA dimensions were significantly larger and atrial Esr was significantly lower in group F than group S (all p < 0.01). LAA_EV and LAA_FV were not different between groups S and F. Multivariate regression analysis showed that a lower Esr and larger transverse LA diameter (LADtr) were independent predictors of failure of cardioversion (HR, 95% CI: 0.36, 0.14–0.88 and 2.85, 1.33–6.10, respectively). Esr combined with LADtr improved the sensitivity and specificity for predicting successful cardioversion. Conclusions SR can be measured in the basal LA wall in atrial fibrillation and the magnitude of the early diastolic SR could predict the success of cardioversion and the likelihood of maintenance of sinus rhythm.
Abstract
The role of radiation pressure in dust migration and the opening of inner cavities in transitional disks is revisited in this paper. Dust dynamics including radiation pressure is often ...studied in axisymmetric models, but in this work, we show that highly non-axisymmetric features can arise from an instability at the inner disk edge. Dust grains clump into high density features there, allowing radiation to leak around them and penetrate deeper into the disk, changing the course of dust migration. Our proof-of-concept, two-dimensional, vertically averaged simulations show that the combination of radiation pressure, shadowing, and gas drag can produce a net outward migration, or recession, of the dust component of the disk. The recession speed of the inner disk edge is on the order of 10
−5
times Keplerian speed in our parameter space, which is faster than the background viscous flow, assuming a Shakura–Sunyaev viscosity
α
≲ 10
−3
. This speed, if sustained over the lifetime of the disk, can result in a dust cavity as large as tens of astronomical units.
Aims
The Pacing to Avoid Cardiac Enlargement (PACE) trial is a prospective, double-blinded, randomized, multicentre study that reported the superiority of biventricular (BiV) pacing to right ...ventricular apical (RVA) pacing in the prevention of left ventricular (LV) adverse remodelling and deterioration of systolic function at 1 year. In the current analysis, we report the results at extended 2-year follow-up for changes in LV function and remodelling.
Methods and results
Patients (n = 177) with bradycardia and preserved LV ejection fraction (EF ≥45%) were randomized to receive RVA or BiV pacing. The co-primary endpoints were LVEF and LV end-systolic volume (LVESV).
Eighty-one (92%) of 88 in the RVA pacing group and 82 (92%) of 89 patients in the BiV pacing group completed 2-year follow-up with a valid echocardiography. In the RVA pacing group, LVEF further decreased from the first to the second year, but it remained unchanged in the BiV pacing group, leading to a significant difference of 9.9 percentage points between groups at 2-year follow-up (P < 0.001). Similarly, LVESV continues to enlarge from the first to the second year in the RVA pacing group, leading to a difference of 13.0 mL (P < 0.001) between groups. Predefined subgroup analysis showed consistent results with the whole study population for both co-primary endpoints, which included patients with pre-existing LV diastolic dysfunction. Eighteen patients in the BiV pacing group (20.2%) and 55 in the RVA pacing group (62.5%) had a significant reduction of LVEF (of ≥5%, P < 0.001).
Conclusion
Left ventricular adverse remodelling and deterioration of systolic function continues at the second year after RVA pacing. This deterioration is prevented by BiV pacing.
A number of noninvasive techniques have been used to predict the effectiveness of cardiac resynchronization therapy (CRT) in heart failure patients, in particular left ventricular (LV) reverse ...remodeling. This study compared the relative predictive values of tissue Doppler imaging (TDI) and strain-rate imaging (SRI) parameters for LV reverse remodeling in patients who received CRT and examined for potential differences in ischemic (n=22) and nonischemic (n=32) heart failure.
TDI and SRI were performed at baseline and 3-month follow-up. Eighteen parameters of intraventricular and interventricular asynchrony based on the time to peak myocardial contraction (Ts) and time to peak strain rate (Tsr) were compared, along with postsystolic shortening (PSS). Reverse remodeling with reduction of LV end-diastolic and end-systolic volumes and gain in ejection fraction (all P<0.001) was observed in the whole study population. The standard deviation of Ts of 12 LV segments (Ts-SD) is the most powerful predictor of reverse remodeling in both the ischemic (r=-0.65, P<0.001) and nonischemic (r=-0.79, P<0.001) groups. The PSS of 12 LV segments was a good predictor only for the nonischemic (r=-0.64, P<0.001) but not the ischemic (r=0.32, P=NS) group. However, parameters of SRI and interventricular asynchrony failed to predict reverse remodeling. By multiple regression analysis, independent parameters included Ts-SD in both groups (P<0.005) and PSS of 12 LV segments in the nonischemic group (P=0.03). The area of the receiver operating characteristic curve was largest for Ts-SD (0.94; CI=0.88 to 1.00).
Ts-SD is the most powerful predictor of LV reverse remodeling and was consistently useful for ischemic and nonischemic heart failure. However, PSS is useful only for nonischemic pathogenesis, whereas the role of SRI parameters was not supported by the present study.
Abstract We present high-resolution spectra and spectroastrometric (SA) measurements of fundamental rovibrational CO emission from nine nearby (≲300 pc) protoplanetary disks where large inner dust ...cavities have been observed. The emission-line profiles and SA signals are fit with a slab disk model that allows the eccentricity of the disk and intensity of the emission to vary as power laws. Six of the sources are well fit with our model, and three of these sources show asymmetric line profiles that can be fit by adopting a nonzero eccentricity. The three other sources have components in either their line profile or SA signal that are not captured by our disk model. Two of these sources (V892 Tau and CQ Tau) have multi-epoch observations that reveal significant variability. CQ Tau and AB Aur have CO line profiles with centrally peaked components that are similar to line profiles which have been interpreted as evidence of molecular gas arising from a wide-angle disk wind. Alternatively, emission from a circumplanetary disk could also account for this component. The interpretations of these results can be clarified in the future with additional epochs that will test the variability timescale of these SA signals. We discuss the utility of using high-resolution spectroscopy for probing the dynamics of gas in the disk and the scenarios that can give rise to profiles that are not fit with a simple disk model.
Abstract
CI Tau is currently the only T Tauri star with an inner protoplanetary disk that hosts a planet, CI Tau b, that has been detected by a radial velocity survey. This provides the unique ...opportunity to study disk features that were imprinted by that planet. We present multiepoch spectroscopic data, taken with NASA IRTF in 2022, of the
12
CO and hydrogen Pf
β
line emissions spanning nine consecutive nights, which is the proposed orbital period of CI Tau b. We find that the star’s accretion rate varied according to that nine-day period, indicative of companion-driven accretion. Analysis of the
12
CO emission lines reveals that the disk can be described with an inner and an outer component spanning orbital radii 0.05–0.13 au and 0.15–1.5 au, respectively. Both components have eccentricities of about 0.05 and arguments of periapsis that are oppositely aligned. We present a proof-of-concept hydrodynamic simulation that shows that a massive companion on a similarly eccentric orbit can recreate a similar disk structure. Our results allude to such a companion being located at an orbital distance of around 0.14 au. However, this planet’s orbital parameters may be inconsistent with those of CI Tau b, whose high eccentricity is likely not compatible with the low disk eccentricities inferred by our model.
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