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The Cassini spacecraft revealed that Saturn's magnetic field displayed oscillations at a period originally thought to match the planetary rotation rate but later found not to. One of many proposed theories predicts that a polar twin‐cell neutral weather system drives this variation, producing observable differences in flows within Saturn's ionosphere. Here, using spectral observations of auroral H3+ ${\mathrm{H}}_{3}^{+}$ emission lines taken by the Keck Observatory's Near Infrared Echelle Spectrograph (Keck‐NIRSPEC) in 2017, we derive ion line‐of‐sight velocity maps after grouping spectra into rotational quadrants matching phases of the planetary magnetic field. We measure 0.5 km s−1 wind systems in the ionosphere consistent with predicted neutral twin‐vortex flow patterns. These findings demonstrate that neutral winds in Saturn's polar regions cause the rotational period, as determined via the magnetic field, to exhibit differences and time variabilities relative to the planet's true period of rotation in a process never before seen within planetary atmospheres. Plain Language Summary: We observed Saturn's northern aurorae in the infrared using the Keck Observatory in Mauna Kea, Hawaii over the course of June, July and August of 2017. Using this data we investigate the motion of an ion, H3+ ${\mathrm{H}}_{3}^{+}$, in the planet's upper atmosphere. This is done after first placing the data into four groups corresponding to the rotational phase of the planet's magnetic field. By doing so we are able to detect twin‐vortex flows in the upper atmosphere of Saturn, consistent with theories that predict the presence of such a polar feature, thus providing direct evidence that Saturn's measured variable rotation rate is driven by these flows. These twin‐vortex flows are ultimately responsible for the time differences relative to the planet's true rotation period observed throughout Saturn's planetary environment. Key Points: Keck‐NIRSPEC observations of Saturn's northern H3+ infrared auroral emission from 2017 are analyzedFirst clear picture of how the ionosphere moves in relation to planetary period currents is providedSaturn's measured variable rotation rate is driven by twin‐vortex flows in the upper atmosphere [ABSTRACT FROM AUTHOR]

Auroral emissions have been extensively observed at the Earth, Jupiter, and Saturn. These planets all have appreciable atmospheres and strong magnetic fields, and their auroras predominantly originate from a region encircling each magnetic pole. However, Jupiter's auroras poleward of these "main" emissions are brighter and more dynamic, and the drivers responsible for much of these mysterious polar auroras have eluded identification to date. We propose that part of the solution may stem from Jupiter's stronger magnetic field. We model large‐scale Alfvénic perturbations propagating through the polar magnetosphere toward Jupiter, showing that the resulting <0.1° deflections of the magnetic field closest to the planet could trigger magnetic reconnection as near as ∼0.2 Jupiter radii above the cloud tops. At Earth and Saturn this physics should be negligible, but reconnection electric field strengths above Jupiter's poles can approach ∼1 V m−1, typical of the solar corona. We suggest this near‐planet reconnection could generate beams of high‐energy electrons capable of explaining some of Jupiter's polar auroras. Plain Language Summary: When energetic particles from space hit a planet's upper atmosphere the resulting chemistry can produce light, leading to spectacular "auroras." Jupiter is the largest planet in the Solar System, with the strongest magnetic field generated in its interior, and with the brightest auroras. We understand why Jupiter's auroras are so bright to a large extent, but a long‐standing mystery is what causes the swirling auroras around Jupiter's poles, which we do not see at other planets. We present a new idea that might lead to a solution to this problem. We show that under certain conditions in space just above Jupiter's polar atmosphere some of the energy stored in the planet's magnetic field can be released, possibly accelerating particles and producing auroras below. If this idea is supported by future research it would imply that Jupiter's bright polar auroras are due to the planet's very strong magnetic field, with implications for similarly strongly magnetized planets in orbit around distant stars. Key Points: Magnetic reconnection can happen a few planetary radii from Jupiter when its magnetic field is locally sheared on plasma kinetic scalesWhile negligible at weakly magnetized planets, reconnection electric fields near Jupiter's poles can be as strong as in the solar coronaThese reconnection events could generate high‐energy electron beams, contributing to an explanation for Jupiter's mysterious polar auroras [ABSTRACT FROM AUTHOR]

We present a study of Saturn's H3+ northern auroral emission using data from 19 May 2013 from the Very Large Telescope's long‐slit spectrometer Cryogenic Infrared Echelle Spectrograph (VLT‐CRIRES). Adaptive optics, combined with the spectral resolution of VLT‐CRIRES (λΔλ∼100,000), offers unprecedented spectrally resolved views of Saturn's infrared aurora. Discrete H3+ emission lines—used to derive dawn‐to‐dusk profiles of auroral intensity, ion line‐of‐sight velocity, and thermospheric temperature—reveal a dawn‐enhanced aurora with an average temperature of 361 (±48) K and a localized dark region in the emission co‐located with a noon‐to‐midnight (and vice versa) flow in the ion velocity on the scale of ∼1 km/s, resembling an ionospheric polar vortex. A temperature hotspot of 379 (±66) K may be driving an emission region, corresponding to a location where H3+ is failing to cool the thermosphere. Results presented here have implications for current understanding on the complex nature of Saturn's thermosphere‐ionosphere‐magnetosphere interaction. Key Points: High spectral resolution profiles of H3+ parameters from Saturn's northern aurora are derived using spectroscopic data from VLT‐CRIRESThe velocity flow of H3+ ions is consistent with the behavior of a relatively small ionospheric polar vortexThe H3+ temperature profile reveals a subtle and previously undetected gradient, which increases across the polar cap going from dawn to dusk [ABSTRACT FROM AUTHOR]

Abstract: We present a detailed study of the H3+ auroral emissions at Jupiter, using data taken on 31 December 2012 with the long‐slit Echelle spectrometer CRIRES (ESO‐VLT). From this data set the rotational temperature of the H3+ ions in Jupiter's upper atmosphere was calculated using the ratio of the ν2 Q(1,0−) and ν2 Q(3,0−) fundamental emission lines. The entire northern auroral region was observed, providing a highly detailed view of ionospheric temperatures, which were mapped onto polar projections. The temperature range we derive in the northern auroral region is ~750–1000 K, which is consistent with past studies, although the temperature structure differs. We identify two broad regions which exhibit temperature changes over a short period of time (~80 minutes). We propose that the changes in temperature could be due to a local time change in particle precipitation energy, or they could be caused by dynamic temperature changes generated in the neutral thermosphere due to the magnetospheric response to a transient enhancement of solar wind dynamic pressure, as predicted by models. By comparing the H3+ temperature, column density, total emission, and line‐of‐sight velocity, we were unable to identify a single dominant mechanism responsible for the energetics in Jupiter's northern auroral region. The comparison reveals that there is complex interplay between heating by impact from particle precipitation and Joule heating, as well as cooling by the H3+ thermostat effect. [ABSTRACT FROM AUTHOR]

SUMMARY An effective way of using computational fluid dynamics (CFD) to simulate flow about a rotating device-for example, a wind or marine turbine-is to embed a rotating region of cells inside a larger, stationary domain, with a sliding interface between. This paper describes a simple but effective method for implementing this as an internal Dirichlet boundary condition, with interfacial values obtained by interpolation from halo nodes. The method is tested in two finite-volume codes: one using block-structured meshes and the other unstructured meshes. Validation is performed for flow around simple, isolated, rotating shapes (cylinder, sphere and cube), comparing, where possible, with experiment and the alternative CFD approach of fixed grid with moving walls. Flow variables are shown to vary smoothly across the sliding interface. Simulations of a tidal-stream turbine, including both rotor and support, are then performed and compared with towing-tank experiments. Comparison between CFD and experiment is made for thrust and power coefficients as a function of tip-speed ratio (TSR) using Reynolds-averaged Navier-Stokes turbulence models and large-eddy simulation (LES). Performance of most models is good near the optimal TSR, but simulations underestimate mean thrust and power coefficients in off-design conditions, with the standard k- ϵ turbulence model performing noticeably worse than shear stress transport k- ω and Reynolds-stress-transport closures. LES gave good predictions of mean load coefficients and vital information about wake structures but at substantial computational cost. Grid-sensitivity studies suggest that Reynolds-averaged Navier-Stokes models give acceptable predictions of mean power and thrust coefficients on a single device using a mesh of about 4 million cells. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

1 Thirteen hypertensive patients completed a double-blind comparison of placebo, acebutolol 200 mg twice daily and acebutolol 400 mg once daily, administered for 4 weeks in random order. 2 Blood pressure and heart rate were significantly reduced by both acebutolol treatments. The mean reduction of resting pressure 12 h after 200 mg twice daily (12/7 mmHg) was similar to that 24 hr after 400 mg once daily (13/9 mmHg). 3 Compared to placebo, reductions in exercise heart rate and systolic pressure at 12 h after 200 mg twice daily and 24 h after 400 mg once daily were significant and similar. 4 Beta-adrenoceptor antagonism was also assessed by inhibition of the heart rate response to sublingual glyceryl trinitrate taken in the standing position. Both acebutolol treatments reduced the response; the reduction after twice daily treatment (mean 25 beats/min) was significantly greater than after once daily treatment (mean 19 beats/min). 5 There was no difference in blood pressure control between acebutolol administered once and twice daily in a total daily dose of 400 mg.

The effect of felodipine 10 mg oral solution or placebo on peripheral haemodynamics and the response of the forearm resistance vessels to venous occlusion was studied in seven normotensive individuals. Felodipine produced a significant fall in diastolic blood pressure (DBP max = -15 mm Hg), a rise in heart rate (heart rate max = +15 beats min-1) (both P less than 0.01), and an overall fall in calculated forearm vascular resistance (calculated forearm vascular resistance max = -19.6 units, P less than 0.001). Felodipine had no significant effect on the vasodilator response, but limited the vasoconstrictor response following venous occlusion. These observations suggest that felodipine is a potent vasodilator and interferes with the myogenic response of vascular smooth muscle of the forearm resistance vessels.

1 Ten untreated hypertensive patients underwent 24 h continuous intra-arterial ambulatory monitoring of blood pressure (BP) and M-mode echocardiography. 2 They were treated with once-daily timolol and followed up at 2, 4, 8 and 12 weeks when dosage was titrated against BP control (indirect measurement) and degree of beta-adrenoceptor antagonism (submaximal bicycle ergometry and sub-lingual GTN). 3 Sixteen weeks after commencing therapy, nine patients underwent repeat continuous ambulatory monitoring of BP and M-mode echocardiography. 4 Casual BP was significantly reduced during the follow-up period at 2, 4, 8 and 12 weeks. 5 A reduction of BP was seen throughout the 24 h although this did not achieve statistical significance when sympathetic activity was low. 6 Echocardiographic measurement of left ventricular mass was significantly reduced after 16 weeks treatment.

Seven untreated patients with essential hypertension but without target organ damage were admitted to hospital. Urine was collected the following day from 08.00 to 13.00 h, 13.00 to 18.00 h, and 18.00 to 08.00 h. The protocol was repeated the next day following 30 mg oral nicardipine. Intra-arterial blood pressure (IABP), plasma volume, and plasma renin activity (PRA) also were measured daily. Following the single-dose study, the patients were treated as outpatients and received oral nicardipine 20, 30, or 40 mg four times daily. They were readmitted 2 months later for further study, at which time the protocol was repeated. Urine output between 08.00 and 13.00 h significantly increased after the single- and multiple-dose studies. Following the single-dose study, this diuresis was associated with a natriuresis. Urine output increased over the 24 h following multiple-dose treatment, but this increase was not statistically significant. During the multiple-dose 24 h study, there was an increase in urinary potassium (P less than 0.05). Mean IABP was reduced significantly after the single- and multiple-dose studies (P less than 0.02 and less than 0.05, respectively). During the study, there were no significant changes in plasma volume, weight, or plasma renin activity.