Inhomogeneous terminators on the exoplanet WASP-39 b.

Transmission spectroscopy has been a workhorse technique used over the past two decades to constrain the physical and chemical properties of exoplanet atmospheres1-5. One of its classical key assumptions is that the portion of the atmosphere it probes-the terminator region-is homogeneous. Several works from the past decade, however, have put this into question for highly irradiated, hot (Teq ≳ 1,000 K) gas giant exoplanets, both empirically6-10 and through three-dimensional modelling11-17. While models have predicted clear differences between the evening (day-to-night) and morning (night-to-day) terminators, direct morning and evening transmission spectra in a wide wavelength range have not been reported for an exoplanet so far. Under the assumption of precise and accurate orbital parameters for the exoplanet WASP-39 b, here we report the detection of inhomogeneous terminators on WASP-39 b, which has allowed us to retrieve its morning and evening transmission spectra in the near-infrared (2-5 µm) using the James Webb Space Telescope. We have observed larger transit depths in the evening, which are, on average, 405 ± 88 ppm larger than the morning ones, and also have qualitatively larger features than the morning spectrum. The spectra are best explained by models in which the evening terminator is hotter than the morning terminator by 17 7 - 57 + 65 K, with both terminators having C/O ratios consistent with solar. General circulation models predict temperature differences broadly consistent with the above value and point towards a cloudy morning terminator and a clearer evening terminator.

A broadband thermal emission spectrum of the ultra-hot Jupiter WASP-18b.

Close-in giant exoplanets with temperatures greater than 2,000 K ('ultra-hot Jupiters') have been the subject of extensive efforts to determine their atmospheric properties using thermal emission measurements from the Hubble Space Telescope (HST) and Spitzer Space Telescope1-3. However, previous studies have yielded inconsistent results because the small sizes of the spectral features and the limited information content of the data resulted in high sensitivity to the varying assumptions made in the treatment of instrument systematics and the atmospheric retrieval analysis3-12. Here we present a dayside thermal emission spectrum of the ultra-hot Jupiter WASP-18b obtained with the NIRISS13 instrument on the JWST. The data span 0.85 to 2.85 µm in wavelength at an average resolving power of 400 and exhibit minimal systematics. The spectrum shows three water emission features (at >6σ confidence) and evidence for optical opacity, possibly attributable to H-, TiO and VO (combined significance of 3.8σ). Models that fit the data require a thermal inversion, molecular dissociation as predicted by chemical equilibrium, a solar heavy-element abundance ('metallicity', [Formula: see text] times solar) and a carbon-to-oxygen (C/O) ratio less than unity. The data also yield a dayside brightness temperature map, which shows a peak in temperature near the substellar point that decreases steeply and symmetrically with longitude towards the terminators.

Early Release Science of the exoplanet WASP-39b with JWST NIRISS.

The Saturn-mass exoplanet WASP-39b has been the subject of extensive efforts to determine its atmospheric properties using transmission spectroscopy1-4. However, these efforts have been hampered by modelling degeneracies between composition and cloud properties that are caused by limited data quality5-9. Here we present the transmission spectrum of WASP-39b obtained using the Single-Object Slitless Spectroscopy (SOSS) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument on the JWST. This spectrum spans 0.6-2.8 µm in wavelength and shows several water-absorption bands, the potassium resonance doublet and signatures of clouds. The precision and broad wavelength coverage of NIRISS/SOSS allows us to break model degeneracies between cloud properties and the atmospheric composition of WASP-39b, favouring a heavy-element enhancement ('metallicity') of about 10-30 times the solar value, a sub-solar carbon-to-oxygen (C/O) ratio and a solar-to-super-solar potassium-to-oxygen (K/O) ratio. The observations are also best explained by wavelength-dependent, non-grey clouds with inhomogeneous coverageof the planet's terminator.

Detection of titanium oxide in the atmosphere of a hot Jupiter.

As an exoplanet transits its host star, some of the light from the star is absorbed by the atoms and molecules in the planet's atmosphere, causing the planet to seem bigger; plotting the planet's observed size as a function of the wavelength of the light produces a transmission spectrum. Measuring the tiny variations in the transmission spectrum, together with atmospheric modelling, then gives clues to the properties of the exoplanet's atmosphere. Chemical species composed of light elements-such as hydrogen, oxygen, carbon, sodium and potassium-have in this way been detected in the atmospheres of several hot giant exoplanets, but molecules composed of heavier elements have thus far proved elusive. Nonetheless, it has been predicted that metal oxides such as titanium oxide (TiO) and vanadium oxide occur in the observable regions of the very hottest exoplanetary atmospheres, causing thermal inversions on the dayside. Here we report the detection of TiO in the atmosphere of the hot-Jupiter planet WASP-19b. Our combined spectrum, with its wide spectral coverage, reveals the presence of TiO (to a confidence level of 7.7σ), a strongly scattering haze (7.4σ) and sodium (3.4σ), and confirms the presence of water (7.9σ) in the atmosphere.

Frequency of cardiovascular events in women with a congenitally bicuspid aortic valve in a single community and effect of pregnancy on events.

Pregnancy and congenitally bicuspid aortic valve (BAV) are thought to be risk factors for aortic dissection; however, the population-based risk for patients with the 2 risk factors remains unknown. We investigated the relation between pregnancy and ascending aortic events in women with congenital BAV living in Olmsted County, Minnesota. Our institutional echocardiographic database was searched for women residing in Olmsted County with congenital BAV diagnosed from 1980 to 1999. We reviewed medical records for end points of aortic events (dilatation, dissection, or surgery) and aortic valve replacement (AVR). Obstetric history and further outcome follow-up were collected by postal survey. We identified 88 women with BAV. Median age at diagnosis was 35 years. Obstetric history totaled 216 pregnancies and 186 deliveries. There were no aortic dissections. During follow-up (median 12.3 years), 24 patients underwent AVR (n = 14), ascending aortic surgery (n = 3), or AVR and ascending aortic surgery (n = 7). Pregnancy was not associated with dilatation of the aorta, aorta surgery, or AVR. At echocardiographic diagnosis of BAV, 5 patients (6%) had aortas >40 mm in greatest diameter and 1 patient has >50 mm. Of 60 patients with serial echocardiograms for comparison (median interval 10.7 years), 21 patients (35%) had aortas measuring >40 mm in greatest dimension and 2 patients had >50 mm. In conclusion, aortic dissection in women with BAV and pregnancy is rare in the community. There is a significant rate of progressive enlargement of the aorta, warranting longitudinal follow-up.

Papillary fibroelastomas in 19 patients with hypertrophic cardiomyopathy undergoing septal myectomy.

BACKGROUND: The aim of this study was to characterize papillary fibroelastomas (PFEs) and their clinical sequelae in patients with hypertrophic cardiomyopathy (HCM). PFE is the third most common primary cardiac tumor and can be associated with neurologic events. Because endocardial trauma has been implicated in its pathogenesis, the occurrence and outcomes of PFEs in patients with HCM were retrospectively analyzed in this study. METHODS: Echocardiograms and medical records were reviewed for characteristics of PFEs in 19 patients with HCM who underwent septal myectomy. RESULTS: PFEs were detected preoperatively by transthoracic echocardiography in 5 patients, by transesophageal echocardiography in 2 patients, and perioperatively in 12 others. Three patients had previously undergone septal myectomy. Although the majority of patients (n = 11 [58%]) had 1 PFE, the number ranged from 1 to >40 (median, 1.0). PFEs arose on the aortic valve (47%), in the left ventricular outflow tract (42%), and in the right heart (11%). CONCLUSIONS: In this study of patients with HCM, 89% of PFEs were located on the aortic valve or in the left ventricular outflow tract compared with about 40% to 50% in prior studies of PFEs in general. This suggests that endocardial trauma due to turbulent left ventricular outflow tract flow may predispose to PFE development. Because of the high incidence of neurologic events among patients with HCM, PFEs may not be innocuous and should be searched for in patients with HCM and unexplained neurologic events.

Location of coronary culprit lesions at autopsy in 41 nondiabetic patients with acute myocardial infarction.

BACKGROUND: Coronary artery disease and myocardial infarction (MI) are major causes of patient morbidity, hospital mortality, and out-of-hospital sudden death. The precise location of culprit lesions in acute MI at autopsy has not been reported. OBJECTIVE: The purpose of this retrospective histopathologic autopsy study was to determine the distribution of coronary culprit lesions in acute fatal MI. METHODS: Cross-sections of epicardial coronary arteries were evaluated microscopically. For each culprit lesion, its distance from the coronary ostium and its grade of luminal stenosis were recorded. RESULTS: The study group included 41 nondiabetic patients (mean age of 65 years, 66% males) who underwent autopsy at Mayo Clinic Rochester (1994-2005). Culprit lesions occurred within the proximal 3.0 cm of the left anterior descending artery in 86% and the left circumflex artery in 100%. In contrast, culprit plaques within the right coronary artery (RCA) were distributed evenly throughout its length. CONCLUSIONS: Among nondiabetic patients with acute fatal MI, culprit lesions exhibited proximal clustering in the left anterior descending artery and left circumflex artery, in contrast to more uniform distribution in the RCA. Thus, for the autopsy investigation of sudden death, evaluation for culprit lesions in the entire length of the RCA, not just its proximal region, is recommended.

Short- and long-term efficacy of aspirin and clopidogrel for thromboprophylaxis for mechanical heart valves: an in vivo study in swine.

OBJECTIVE: In the interest of exploring alternatives to warfarin, we tested the hypothesis that clopidogrel combined with aspirin is effective for thromboprophylaxis of mechanical valves using a swine model. METHODS: Adult swine underwent heterotopic implantation of a modified bileaflet mechanical valved conduit bypassing the ligated, native descending thoracic aorta. Animals were randomized to no anticoagulation (n = 7), 175 U/kg dalteparin administered subcutaneously twice daily (n = 9), 325 mg of aspirin (n = 6), 75 mg of clopidogrel (n = 6), or 325 mg of aspirin and 75 mg of clopidogrel daily (n = 6) and survived for 30 days. Additionally, 11 animals were randomized to no anticoagulation (n = 5) or 325 mg of oral aspirin and 75 mg of clopidogrel daily (n = 6) and survived for 150 days. RESULTS: At 30 days, we observed 216 +/- 270 mg of thrombus for the no anticoagulation group, 53 +/- 91 mg for the dalteparin group, 33 +/- 23 mg for the aspirin group, 25 +/- 10 mg for the clopidogrel group, and 17 +/- 9 mg for the combined aspirin and clopidogrel group, respectively (P < .01 for clopidogrel and aspirin vs no anticoagulation). At 150 days, we observed 223 +/- 200 mg of thrombus for the no anticoagulation group and 4 +/- 4 mg for the aspirin and clopidogrel group (P = .02). Mean platelet deposition on the valve was 4.1 x 10(9) +/- 3.6 x 10(9) for the no anticoagulation and 6.81 x 10(7) +/- 1.4 x 10(8) for the combined aspirin and clopidogrel groups, respectively (P = .03). No major hemorrhagic events were observed. CONCLUSIONS: Effective short- and long-term thromboprophylaxis of mechanical valves can be achieved by using dual-antiplatelet therapy in this porcine model. Prospective human trials should be conducted with combination aspirin and clopidogrel as an alternative to warfarin in patients with bileaflet mechanical aortic valves.