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.

Nightside clouds and disequilibrium chemistry on the hot Jupiter WASP-43b.

Hot Jupiters are among the best-studied exoplanets, but it is still poorly understood how their chemical composition and cloud properties vary with longitude. Theoretical models predict that clouds may condense on the nightside and that molecular abundances can be driven out of equilibrium by zonal winds. Here we report a phase-resolved emission spectrum of the hot Jupiter WASP-43b measured from 5 µm to 12 µm with the JWST's Mid-Infrared Instrument. The spectra reveal a large day-night temperature contrast (with average brightness temperatures of 1,524 ± 35 K and 863 ± 23 K, respectively) and evidence for water absorption at all orbital phases. Comparisons with three-dimensional atmospheric models show that both the phase-curve shape and emission spectra strongly suggest the presence of nightside clouds that become optically thick to thermal emission at pressures greater than ~100 mbar. The dayside is consistent with a cloudless atmosphere above the mid-infrared photosphere. Contrary to expectations from equilibrium chemistry but consistent with disequilibrium kinetics models, methane is not detected on the nightside (2σ upper limit of 1-6 ppm, depending on model assumptions). Our results provide strong evidence that the atmosphere of WASP-43b is shaped by disequilibrium processes and provide new insights into the properties of the planet's nightside clouds. However, the remaining discrepancies between our observations and our predictive atmospheric models emphasize the importance of further exploring the effects of clouds and disequilibrium chemistry in numerical models.

Comparative Study of Retroperitoneal Laparoscopic Versus Open Ipsilateral Nephrectomy After Percutaneous Nephrostomy: A Multicenter Analysis.

Purpose: To investigate the feasibility of retroperitoneal laparoscopic ipsilateral nephrectomy of a benign nonfunctional kidney after percutaneous nephrostomy, and to compare this method with open surgery. Materials and Methods: Data from 70 patients who underwent simple nephrectomy from January 2014 to October 2018 at three large centers were retrospectively analyzed. All patients underwent percutaneous nephrostomy because of renal or ureteral calculi with severe hydronephrosis or pyonephrosis. Simple nephrectomy was performed via retroperitoneal laparoscopic surgery (retroperitoneal laparoscopic group; n = 33) or open surgery (open group; n = 37). The retroperitoneal laparoscopic and open groups were compared regarding preoperative variables (age, sex, location of surgery, hypertension, diabetes, BMI, preoperative serum creatinine level, American Society of Anesthesiologists (ASA) grade, fistula duration, fistula size, number of fistulae, and urinary tract infection), and perioperative variables (operation time, intraoperative blood loss, postoperative drainage volume, catheter indwelling time, gastrointestinal function recovery time, duration of bedrest, duration of postoperative hospitalization, postoperative hemoglobin decline, perioperative transfusion, and postoperative complications). Results: The retroperitoneal laparoscopic group included more patients with hydronephrosis, while the open group included more patients with pyonephrosis. There were no significant differences between the two groups in age (P = .813), sex (P = .729), location of surgery (P = .345), hypertension (P = .271), diabetes (P = .394), BMI (P = .798), preoperative serum creatinine level (P = .826), ASA grade (P = .820), fistula duration (P = .108), fistula size (P = .958), number of fistulae (P = .925), urinary tract infection (P = .111), or operative time (P = .851). The retroperitoneal laparoscopic group had significantly lesser intraoperative blood loss (P = .007), postoperative drainage volume (P = .008), shorter catheter indwelling time (P = .002), gastrointestinal function recovery time (P < .001), duration of bedrest (P < .001), and duration of postoperative hospitalization (P < .001), and lesser postoperative hemoglobin decline (P = .035) compared with the open group. Conclusions: Retroperitoneal laparoscopic ipsilateral nephrectomy is feasible for a benign nonfunctional kidney after percutaneous nephrostomy. The surgical method should be selected based on the surgeon's experience and the specific situation of the patient.