The nightside cloud-top circulation of the atmosphere of Venus.

Although Venus is a terrestrial planet similar to Earth, its atmospheric circulation is much different and poorly characterized1. Winds at the cloud top have been measured predominantly on the dayside. Prominent poleward drifts have been observed with dayside cloud tracking and interpreted to be caused by thermal tides and a Hadley circulation2-4; however, the lack of nightside measurements over broad latitudes has prevented the unambiguous characterization of these components. Here we obtain cloud-tracked winds at all local times using thermal infrared images taken by the Venus orbiter Akatsuki, which is sensitive to an altitude of about 65 kilometres5. Prominent equatorward flows are found on the nightside, resulting in null meridional velocities when these are zonally averaged. The velocity structure of the thermal tides was determined without the influence of the Hadley circulation. The semidiurnal tide was found to have an amplitude large enough to contribute to the maintenance of the atmospheric superrotation. The weakness of the mean meridional flow at the cloud top implies that the poleward branch of the Hadley circulation exists above the cloud top and that the equatorward branch exists in the clouds. Our results should shed light on atmospheric superrotation in other celestial bodies.

How waves and turbulence maintain the super-rotation of Venus' atmosphere.

Venus has a thick atmosphere that rotates 60 times as fast as the surface, a phenomenon known as super-rotation. We use data obtained from the orbiting Akatsuki spacecraft to investigate how the super-rotation is maintained in the cloud layer, where the rotation speed is highest. A thermally induced latitudinal-vertical circulation acts to homogenize the distribution of the angular momentum around the rotational axis. Maintaining the super-rotation requires this to be counteracted by atmospheric waves and turbulence. Among those effects, thermal tides transport the angular momentum, which maintains the rotation peak, near the cloud top at low latitudes. Other planetary-scale waves and large-scale turbulence act in the opposite direction. We suggest that hydrodynamic instabilities adjust the angular-momentum distribution at mid-latitudes.

Planetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer.

Cloud patterns are important clues for revealing the atmospheric circulation of Venus. Recently, a planetary-scale streak structure has been discovered in middle- and lower-cloud images of Venus' night-side taken by IR2, the 2-µm camera, on board the Akatsuki orbiter. However, its formation mechanism has not been investigated. Here we succeed, for the first time, in reproducing the patterns of the observed streak structure, as regions of strong downward flows that develop in high-resolution global simulations of the Venus atmosphere. The streaks are formed in both hemispheres with equatorial symmetry, which is caused by equatorial Rossby-like and Kelvin-like waves with zonal wavenumber one. The low-stability layer that has been suggested by past observations is essential for reproducing the streak structure. The streaks of downward flow result from the interaction of the meridionally tilted phase lines of the Rossby-like waves and the characteristics of baroclinic instability produced around the low-stability layer.

Ultraviolet imager on Venus orbiter Akatsuki and its initial results.

The ultraviolet imager (UVI) has been developed for the Akatsuki spacecraft (Venus Climate Orbiter mission). The UVI takes ultraviolet (UV) images of the solar radiation reflected by the Venusian clouds with narrow bandpass filters centered at the 283 and 365 nm wavelengths. There are absorption bands of SO2 and unknown absorbers in these wavelength regions. The UV images provide the spatial distribution of SO2 and the unknown absorber around cloud top altitudes. The images also allow us to understand the cloud top morphologies and haze properties. Nominal sequential images with 2-h intervals are used to understand the dynamics of the Venusian atmosphere by estimating the wind vectors at the cloud top altitude, as well as the mass transportation of UV absorbers. The UVI is equipped with off-axial catadioptric optics, two bandpass filters, a diffuser installed in a filter wheel moving with a step motor, and a high sensitivity charge-coupled device with UV coating. The UVI images have spatial resolutions ranging from 200 m to 86 km at sub-spacecraft points. The UVI has been kept in good condition during the extended interplanetary cruise by carefully designed operations that have maintained its temperature maintenance and avoided solar radiation damage. The images have signal-to-noise ratios of over 100 after onboard desmear processing.

Venus looks different from day to night across wavelengths: morphology from Akatsuki multispectral images.

Since insertion into orbit on December 7, 2015, the Akatsuki orbiter has returned global images of Venus from its four imaging cameras at eleven discrete wavelengths from ultraviolet (283 and 365 nm) and near infrared (0.9-2.3 µm), to the thermal infrared (8-12 µm) from a near-equatorial orbit. The Venus Express and Pioneer Venus Orbiter missions have also monitored the planet for long periods but from polar or near-polar orbits. The wavelength coverage and views of the planet also differ for all three missions. In reflected light, the images reveal features seen near the cloud tops (~ 70 km altitude), whereas in the near-infrared images of the nightside, features seen are at mid- to lower cloud levels (~ 48-60 km altitude). The dayside cloud cover imaged at the ultraviolet wavelengths shows morphologies similar to what was observed from Mariner 10, Pioneer Venus, Galileo, Venus Express and MESSENGER. The daytime images at 0.9 and 2.02 µm also reveal some interesting features which bear similarity to the ultraviolet images. The nighttime images at 1.74, 2.26 and 2.32 µm and at 8-12 µm reveal features not seen before and show new details of the nightside including narrow wavy ribbons, curved string-like features, long-scale waves, long dark streaks, isolated bright spots, sharp boundaries and even mesoscale vortices. Some features previously seen such as circum-equatorial belts (CEBs) and occasional areal brightenings at ultraviolet (seen in Venus Express observations) of the cloud cover at ultraviolet wavelengths have not been observed thus far. Evidence for the hemispheric vortex organization of the global circulation can be seen at all wavelengths on the day- and nightsides. Akatsuki images reveal new and puzzling morphology of the complex nightside cloud cover. The cloud morphologies provide some clues to the processes occurring in the atmosphere and are thus, a key diagnostic tool when quantitative dynamical analysis is not feasible due to insufficient information.

Initiation of a lightning search using the lightning and airglow camera onboard the Venus orbiter Akatsuki.

The existence of lightning discharges in the Venus atmosphere has been controversial for more than 30 years, with many positive and negative reports published. The lightning and airglow camera (LAC) onboard the Venus orbiter, Akatsuki, was designed to observe the light curve of possible flashes at a sufficiently high sampling rate to discriminate lightning from other sources and can thereby perform a more definitive search for optical emissions. Akatsuki arrived at Venus during December 2016, 5 years following its launch. The initial operations of LAC through November 2016 have included a progressive increase in the high voltage applied to the avalanche photodiode detector. LAC began lightning survey observations in December 2016. It was confirmed that the operational high voltage was achieved and that the triggering system functions correctly. LAC lightning search observations are planned to continue for several years.

The Great Cold Spot in Jupiter's upper atmosphere.

Past observations and modeling of Jupiter's thermosphere have, due to their limited resolution, suggested that heat generated by the aurora near the poles results in a smooth thermal gradient away from these aurorae, indicating a quiescent and diffuse flow of energy within the subauroral thermosphere. Here we discuss Very Large Telescope-Cryogenic High-Resolution IR Echelle Spectrometer observations that reveal a small-scale localized cooling of ~200 K within the nonauroral thermosphere. Using Infrared Telescope Facility NSFCam images, this feature is revealed to be quasi-stable over at least a 15 year period, fixed in magnetic latitude and longitude. The size and shape of this "Great Cold Spot" vary significantly with time, strongly suggesting that it is produced by an aurorally generated weather system: the first direct evidence of a long-term thermospheric vortex in the solar system. We discuss the implications of this spot, comparing it with short-term temperature and density variations at Earth.

Equatorial jet in the lower to middle cloud layer of Venus revealed by Akatsuki.

The Venusian atmosphere is in a state of superrotation where prevailing westward winds move much faster than the planet's rotation. Venus is covered with thick clouds that extend from about 45 to 70 km altitude, but thermal radiation emitted from the lower atmosphere and the surface on the planet's night-side escapes to space at narrow spectral windows of near-infrared. The radiation can be used to estimate winds by tracking the silhouettes of clouds in the lower and middle cloud regions below about 57 km in altitude. Estimates of wind speeds have ranged from 50 to 70 m/s at low- to mid-latitudes, either nearly constant across latitudes or with winds peaking at mid-latitudes. Here we report the detection of winds at low latitude exceeding 80 m/s using IR2 camera images from the Akatsuki orbiter taken during July and August 2016. The angular speed around the planetary rotation axis peaks near the equator, which we suggest is consistent with an equatorial jet, a feature that has not been observed previously in the Venusian atmosphere. The mechanism producing the jet remains unclear. Our observations reveal variability in the zonal flow in the lower and middle cloud region that may provide new challenges and clues to the dynamics of Venus's atmospheric superrotation.

Correlation between salivary interleukin-6 levels and early locoregional recurrence in patients with oral squamous cell carcinoma: preliminary study.

BACKGROUND: We have demonstrated that salivary interleukin-6 (IL-6) concentrations change during the treatment in patients with oral squamous cell carcinoma (OSCC). We sought to elucidate the correlations between salivary IL-6 concentration and early locoregional recurrence in OSCC. METHODS: Stimulated saliva was collected before and after surgery from 27 consecutive patients with OSCC. Recurrence-free survival (RFS) curves were plotted using the Kaplan-Meier method. RESULTS: Of the 27 patients, 11 (41%) were diagnosed with locoregional recurrence within 24 months postsurgery. The median concentrations of IL-6 presurgery and postsurgery were 2.8 pg/mL and 2.1 pg/mL, respectively. The median postsurgery concentration of IL-6 was significantly higher in patients with than without locoregional recurrence (p = .02). Multivariate analysis revealed that postsurgery salivary IL-6 concentration was an independent risk factor for locoregional recurrence (p = .03; risk ratio, 0.14). CONCLUSIONS: Posttreatment concentration of salivary IL-6 may predict early locoregional recurrence in OSCC.

Pain may predict poor prognosis in patients with oral squamous cell carcinoma.

OBJECTIVE: We have previously reported that the histologic mode of invasion of oral squamous cell carcinoma (OSCC) is a significant risk factor for pain. Here we sought to determine whether pain is a risk factor for poor prognosis in patients with OSCC. STUDY DESIGN: We evaluated the relationships between overall survival rates and clinicopathologic variables, including gender, age, T- and N-stages, pathologic findings, and pain in 109 consecutive patients with untreated OSCC. RESULTS: Of these 109 patients, 40 (37%) reported spontaneous pain. Univariate analysis showed that the overall survival rates of patients with spontaneous pain was significantly lower than those of patients without pain (P = .002). Multivariate analysis revealed that spontaneous pain and N-stage were significant independent predictors of overall survival rates. CONCLUSIONS: This is the first report showing that spontaneous pain before treatment may be associated with poor prognosis in patients with OSCC.

[A case of maxillary sinus carcinoma showing long time survival after lung metastasis with administration of S-1 as tumor dormancy therapy].

The patient is a 65-year-old man, who underwent curative resection for maxillary sinus carcinoma after chemoradiation. Lung metastases were observed two months following resection, and were treated with S-1 at a dose of 120 mg/day. One course of the S-1 administration regimen consisted of 2 weeks and a 1-week interval. The patient achieved long survival for 527 days with no adverse reaction. Therefore, this treatment on an outpatient basis greatly contributed to his quality of life. We consider S-1 as a first-line anti-cancer drug for tumor dormancy therapy.

Migration of gutta-percha point from a root canal into the ethmoid sinus.

There have been reports on the migration of teeth or implants into the maxillary sinus, but we know of no report on the migration of a gutta-percha point that had been used to fill a root canal into the ethmoid sinus. We report such a case which presumably migrated through the maxillary sinus.