Seasonal dependence of the vertical distributions of auroral kilometric radiation sources and auroral particle acceleration regions observed by the Akebono satellite

Seasonal variations in the vertical distributions of occurrence probabilities of auroral kilometnc radiation (AKR) sources and auroral acceleration regions indicated by upward-flowing ion (UFI) events were compared based on statistical analyses of plasma waves and energetic particles data observed by the Akebono satellite. The peak altitude in the vertical distribution of occurrence probability of AKR sources whose emission intensities were larger than -150dBW/m^2-Hz occurred at 5000-6000 km in the summer polar region and at 3000-4000 km in the winter polar region. The analyses have also clarified that the vertical distributions of occurrence probabilities of auroral acceleration regions also show seasonal variations that are quite similar to those of the AKR sources. Based on the observation that intense AKR emissions can be generated even in high-density plasma, we suggest that processes other than cyclotron maser instability (CMI), such as mode conversions, may be dominant under conditions of dense ambient plasma in the summer polar regions. The contri-bution of the emissions generated by these mechanisms to the seasonal variations in the vertical distributions of AKR sources is thought to be significant

Control factor of solar cycle variation of auroral kilometric radiation

Solar cycle variations of auroral kilometric radiation (AKR) observed by the Akebono satellite have been compared with the variations of F10.7 and solar wind dynamic pressure. F10.7 and solar wind dynamic pressure show different solar cycle variations: F10.7 increases during solar maximum and decreases during solar minimum. Solar wind dynamic pressure suddenly increases in the declining phase of solar activity and gradually decreases. The pressure minimum occurs during solar maximum. Statistical analysis of the Akebono data has shown that AKR occurrence minimum occurs during solar maximum, however AKR occurrence maximum coincides not with solar wind dynamic pressure peak but with F10.7 minimum. Up-flowing ion (UFI) events and ambient plasma density, which are associated with generation conditions of AKR, also show similar behavior. They are dependent not on solar wind dynamic pressure but on F10.7. These results suggest the anti-correlation between discrete aurora and solar activities, which has been never recognized through the studies on secular variations of auroral phenomena mainly based on old auroral records obtained in mid-latitude regions

Propagation modes and source locations of the auroral kilometric radiation (AKR) identified by using the wave distribution function method

The propagation characteristics of Auroral Kilometric Radiation (AKR), the propagation mode, power flux as well as propagation direction, have been analyzed by applying the wave distribution function method to the Poynting Flux measurement data obtained by the PWS system onboard the Akebono (EXOS-D) satellite. The results revealed that the power flux of O-mode waves was about 10 percent of the X-mode wave intensity in strong AKR emissions. The X-mode AKR waves tend to fill inside the radiation cone of an auroral field line. On the other hand, O-mode AKR showed two different propagation directions, one was directed to almost 90° with respect to the local magnetic field and the other showed angle in the vicinity of 40°. It was shown that the source locations of O-mode AKR waves with the propagation angle of about 40° located close to the source of the intense X-mode AKR waves

SC-related kilometric and hectometric radiations observed by the Akebono satellite in the polar regions

Plasma wave phenomena associated with sudden commencements (SCs) were analyzed using the database of Akebono satellite observations that has been contributed to for more than 13 years, since March 1989. The plasma wave data from 263 satellite passages covering the onsets of SCs included 85 cases of auroral kilometric radiation (AKR) enhancement within a frequency range of 100kHz to 1.2MHz. The majority of the spectra of the SC-related AKR exhibited a two-banded structure with a harmonic relationship. The start time of the AKR enhancements tended to occur after the onset of the SCs, determined using the geomagnetic records of the Kakioka Magnetic Observatory, within a time range of 3 to 8min, with an average delay time of 5.26min. Based on this delay time feature, the magnetic disturbances associated with SCs were thought to propagate from the dayside magnetosphere to the nightside tail region where they compressed the plasma sheet. On the other hand, the data set reveals 19 cases of terrestrial hectometric radiation (THR) that were also associated with SCs appearing within a frequency range of 900kHz to 4MHz. The THR onset tended to occur 1 to 9min after the SC onset, with an average delay time of 5.84min

Development of ultra-low mass and high-rate capable RPC based on Diamond-Like Carbon electrodes for MEG II experiment

A new type of resistive plate chamber with thin-film electrodes based on diamond-like carbon is under development for background identification in the MEG II experiment. Installed in a low-momentum and high-intensity muon beam, the detector is required to have extremely low mass and a high rate capability. A single-layer prototype detector with 2 cm $\times$ 2 cm size was constructed and evaluated to have a high rate capability of 1 MHz/cm$^2$ low-momentum muons. For a higher rate capability and scalability of the detector size, the electrodes to supply high voltage was segmented by implementing a conductive pattern on diamond-like carbon. Using the new electrodes, a four-layer prototype detector was constructed and evaluated to have a 46% detection efficiency with only a single layer active at a rate of $\cal O$(10 kHz). The result is promising to achieve the required detection efficiency of 90% at a rate of 4 MHz/cm$^2$ with all the layers active.Comment: 5 pages, 8 figures. Contribution to XVI Workshop on Resistive Plate Chambers and Related Detectors (RPC2022), September 26-30 2022. Submitted to Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipmen

Sunitinib Versus Sorafenib as Initial Targeted Therapy for mCC-RCC With Favorable/Intermediate Risk: Multicenter Randomized Trial CROSS-J-RCC

Purpose: The present study compared the efficacy of sunitinib and sorafenib as first-line treatment of metastatic clear cell renal cell carcinoma (mCC-RCC) with favorable or intermediate Memorial Sloan Kettering Cancer Center (MSKCC) risk. Patients and methods: Treatment-naive patients with mCC-RCC were randomized to receive open-label sunitinib followed by sorafenib (SU/SO) or sorafenib followed by sunitinib (SO/SU). The primary endpoint was first-line progression-free survival (PFS). The secondary endpoints were total PFS and overall survival (OS). Results: Of the 124 patients enrolled at 39 institutions from February 2010 to July 2012, 120 were evaluated. The median first-line PFS duration was 8.7 and 7.0 months in the SU/SO and SO/SU groups, respectively (hazard ratio [HR], 0.67; 95% confidence interval [CI], 0.42-1.08). The total PFS and OS were not significantly different between the SU/SO and SO/SU groups (27.8 and 22.6 months; HR, 0.73; 95% CI, 0.428-1.246; and 38.4 and 30.9 months; HR, 0.934; 95% CI, 0.588-1.485, respectively). The subgroup analysis revealed that the total PFS with SU/SO was superior to the total PFS with SO/SU in the patients with favorable MSKCC risk and those with Conclusions: No statistically significant differences were found in first-line PFS, total PFS, or OS between the 2 treatment arms (ClinicalTrials.gov identifier, NCT01481870)