Demonstration of 2.65 / 3.3 Gbit per sec X Band Radiowave Down Link Communications from LEO Small Satellite

This paper reports our new communication system and downlink demonstrations with a small satellite of 2.65 Gbps data rate with 64 APSK modulation and 3.3Gbps data rate with 256 APSK modulation by utilizing two circular polarization channels of X band. We have developed an on-board X-band transmitter, an on-board dual circularly polarized-wave antenna with 17dBi gain and \u3e37dB Cross Polarization Discrimination (XPD) and a 10m ground station with 39dB/K of G/T and \u3e37dB XPD for low-crosstalk polarization multiplexing. Since there are not real- time demodulator systems in such high communication speed, the downlinked signals are stored in a data recorder at an antenna site. Afterwards, we decode downlinked signals by using our non-real-time software demodulator. The system was demonstrated in orbit the RAPid Innovative payload demonstration Satellite (RAPIS-1) of JAXA in 2019. We have achieved 2.65 Gbps and 3.3Gbps communication speed in the X-band for LEO satellite at 300 M symbols per second (Msps) and polarization multiplexing of 64APSK (coding rate 4/5) and 256APSK (coding rate 3/4) following DVB-S2X protocol with roll-off factor α=0.05. The communication speeds correspond to of frequency efficiency 8.4 bit/s/Hz and 10.8 bit/s/Hz of frequency utilization efficiency. As far as authors know, these direct downlink communication speeds and frequency utilization efficiencies are the highest ones at present in LEO satellites, excluding bent-pipe communication systems

Truncated KCNQ1 mutant, A178fs/105, forms hetero-multimer channel with wild-type causing a dominant-negative suppression due to trafficking defect

AbstractWe identified a novel mutation Ala178fs/105 missing S3–S6 and C-terminus portions of KCNQ1 channel. Ala178fs/105-KCNQ1 expressed in COS-7 cells demonstrated no current expression. Co-expression with wild-type (WT) revealed a dominant-negative effect, which suggests the formation of hetero-multimer by mutant and WT. Confocal laser microscopy displayed intracellular retention of Ala178fs/105-KCNQ1 protein. Co-expression of the mutant and WT also increased intracellular retention of channel protein compared to WT alone. Our findings suggest a novel mechanism for LQT1 that the truncated S1–S2 KCNQ1 mutant forms hetero-multimer and cause a dominant-negative effect due to trafficking defect

カワラヨモギとオトコヨモギ(キク科)の自然雑種集団とその生物学的位置

[論文] Articl

OSCILIATIONS OF MEMBRANE POTENTIAL AND TENSION IN CANINE VENTRICULAR MUSCLE FIBERS

The membrane potential s and isometric tension of canine ventricular muscle fibers in the K+-free, Ca2+-rich solution developing oscillatory afterpotentials (OAPs) were recorded simultaneously. The OAPs were always accompanied by aftercontractions (ACs). Both activities appeared with almost a similar frequency and timing. The amplitude of the OAPs, ACs and twitch tension were dependent on the basic cycle length of the train as well as on the number of impulses. The manner of this dependence was similar in the OAPs and ACs but showed a slight difference in the twitch tension. The increase in the [Ca2+]0 and the application of isoproterenol caused augmentation of the OAPs during the application. By washing out the drug, the OAPs and ACs quickly recovered to the control level but the twitch tension did not. The application of 2 mM K+ or Rb+ quickly and reversibly abolished the OAPs and ACs with a marked suppression of the twitch tension. One mM of caffeine eliminated the oscillations of both the membrane potentials and tension. The wash-out of caffeine brought about a transient increase in the OAPs and ACs. Two or five mM of procaine caused a complete elimination of the OAPs and ACs. These results suggest that the OAPs are formed by a process related to the cyclic release of Ca2+ from the sarcoplasmic reticulum