Constitution of Polar Substorm and Associated Phenomena in the Southern Polar Region (AERONOMY)

A meridian scanning photometer was designed for investigating the time and space variations of auroral luminosity. With the aid of the quick-scan auroral photometer data of more than 300 clear night hours recorded at Syowa Station, Antarctica (geomagnetic lat. 69.6°S, long. 77.1°E), the following problems are studied: (1) space and time variation of auroral displays, (2) magnetic field variations associated with the space-time auroral displays, (3) relationships among auroras, magnetic field disturbance, magnetic pulsations, VLF hiss, VLF chorus and GNA during the course of substorms. Various kinds of morphological evidence obtained through the above investigations show that a polar substorm consists of the breakup phase and the post-breakup phase. The breakup phase is characterized by a sudden intensification of auroral arc(s) or band(s) and a rapid poleward movement of the intensified aurora(s) with speed of about 1 km/s (Breakup type aurora). The post-breakup phase is defined as diffused auroras or rays which still remain after the intense breakup type aurora(s) have passed away polewards (Post-breakup type aurora). Generally, the post-breakup aurora(s) move towards the equator side. A breakup type aurora is accompanied by a sharp pulsative geomagnetic disturbance (Breakup magnetic disturbance), while a post-breakup type aurora by a gradual negative bay-shape disturbance (Post-breakup magnetic disturbance). It seems that the sharp pulsative disturbance moves polewards together with the moving breakup aurora, while the gradual negative bay stays with the associated post-breakup aurora(s). Thus, the auroral electrojet can also be classified into AEJ-1, which is an intense and narrow electrojet moving together with the breakup aurora, and AEJ-2, which is a comparatively broad and weak electrojet associated with the post-breakup aurora(s). The auroral breakup phase is accompanied not only by a sharp pulsative geomagnetic disturbance but also by VLF hiss emissions, ULF emissions of PiB type and a sharp CNA phenomenon, while the post-breakup aurora is accompanied by a gradual geo-magnetic bay, a gradual, weak CNA, VLF chorus emissions and ULF emissions of PiC type. With reference to \u27the space-time variations in auroras associated with geomagnetic perturbations at Syowa Station, an overall physical picture of dynamic auroral behaviors over the entire polar region is given, as a conclusion

Space-time Variation of Aurora and Geomagnetic Disturbances : Auroral Observations at Syowa Station in Antarctica (AERONOMY)

The program of auroral observations carried out by the 8th wintering party of the Japanese Antarctic Research Expedition, 1967-1968, consisted of 1. All-sky camera 2. Visual and photographic observations of aurora 3. Observation of auroral pulsations 4. Auroral photometry along the geomagnetic meridian 5. Observation of the auroral radio noise. Description of each observation and results obtained are briefly summarized in the following. 1. Space-time variations of aurora and geomagnetic disturbances A meridian scanning photometer was designed for investigating the time and space variations of auroral luminosity. The meridian time-sequence of auroral luminosity (4278Å) was derived from the data obtained by this photometer. Based on this meridian time-sequence of aurora, the space and time variations of aurora during the auroral substorms and the magnetic field variations associated with the auroral displays are investigated in detail. 2. Auroral pulsations A special photometer was designed for investigating the detailed characteristics of auroral pulsations and their relationships with geomagnetic pulsations. Auroral pulsations observed at Syowa Station can be classified into the following five types : A. Irregular fluctuations with large amplitudes observed mostly at the onset of an auroral substorm. B. Pulse-like auroral pulsations with a period of about 20-40 seconds. C. Long-lived auroral pulsations with a sinusoidal waveform. Their period and amplitude are about 10 seconds and a few KR, respectively. D. Rapid fluctuations of auroral luminosity with a period of about 0.5-2.0 seconds. E. Extremely rapid fluctuations with a frequency of about 20-30 Hz. Characteristics of each auroral pulsation are investigated and summarized

Alstiphyllanines E–H, picraline and ajmaline-type alkaloids from Alstonia macrophylla inhibiting sodium glucose cotransporter

Three new picraline-type alkaloids, alstiphyllanines E–G (1–3) and a new ajmaline-type alkaloid, alstiphyllanine H (4) were isolated from the leaves of Alstonia macrophylla together with 16 related alkaloids (5–20). Structures and stereochemistry of 1–4 were fully elucidated and characterized by 2D NMR analysis. Alstiphyllanines E and F (1 and 2) showed moderate Na+-glucose cotransporter (SGLT1 and SGLT2) inhibitory activity. A series of a hydroxy substituted derivatives 21–28 at C-17 of the picraline-type alkaloids have been derived as having potent SGLT inhibitory activity. 10-Methoxy-N(1)-methylburnamine-17-O-veratrate (6) exhibited potent inhibitory activity, suggesting that the presence of an ester side chain at C-17 may be important to show SGLT inhibitory activity. Structure activity relationship of alstiphyllanines on inhibitory activity of SGLT was discussed

マウスモデルを用いたDOHaD検証系の確立：仔の行動表現型、遺伝子発現、ゲノムメチル化に関する網羅的解析

第3回日本DOHaD研究会学術集会　抄録集　【ポスター発表

RAPID AURORAL PULSATIONS WITH FREQUENCIES OF 0.05-40Hz

An image intensifier-television system equipped with an auroral photometer has been installed at Syowa Station to observe the auroral rapid luminosity fluctuations. In addition to the large amplitude auroral fluctuations observed mainly at the time of onset of an auroral substorm, several different spectral types of pulsating auroras are found in the active auroras in the frequency range from 0.05 to 40Hz, the principle dominant spectral frequencies being at about 0.08,1,10 and 25Hz. Study of the association between auroral luminosity and magnetic pulsations shows that correlations are good in case of 0.08Hz fluctuations, while poor in cases of the 1,10 and 25Hz rapid fluctuations

Observations of Wave Phenomena in the Polar Ionosphere by S-210JA-19 Rocket

S-210JA-19 sounding rocket was launched on July 15,1973 from Syowa Station in order to investigate the auroral hiss in the polar ionosphere. On this day a fairly strong hiss was observed on the ground, but auroral arc was not observed. The hiss was also observed on the rocket above an altitude of 80km both in the ascending and the descending phases in the frequency range of 1-8kHz and at 30kHz. The field intensity had a maximum around an altitude of 100km. From these results, it is supposed that in some circumstances auroral hiss is generated at an altitude of about 100km by auroral particles penetrating into the polar ionosphere

Japanese MAP results in Antarctica

As a major program of Japanese MAP, which was conducted in 1982-1985,the coordinated observations for the Antarctic middle atmosphere were carried out at and in the vicinity of Syowa Station. The observations were for the following six items : 1) Dynamics of the middle atmosphere, 2) Atmospheric constituents, 3) Stratospheric and tropospheric aerosols, 4) Wind, wave and tide in the stratosphere, 5) Atmospheric pollution, and 6) Particle precipitation and interaction of the middle atmosphere with the lower ionosphere. The results of some of these observations are reviewed in this report