The rapid burster activity observed from tenma

The Japanese X-ray astronomy satellite Hakucho and Tenma observed the activity of the rapid burster MXB 1730-335 in 1979 and 1983. In the first observation from 8 to 22 August 1979, the activity began with rapidly repetitive type II bursts which are similar to those observed earlier. Then the energy per burst quickly increased and evolved to exhibit a long flat top or roughly trapezoidal shape. In the last phase, burst size became smaller and the activity returned to the short type II burst mode. In the second observation from 5 to 31 August 1983, the burster started to emit a train of bursts which aparently resemble to type I bursts with quasi-periodical occurrence of 74 ～ 90 minutes. In the second phase, there appeared long type II bursts of trapezoidal profiles and exotic long bursts. In the last phase, about 3000 rapidly repetitive short type II bursts were observed. The bursts with shortest intervals exhibited almost periodic features of 16 sec.The type II bursts in both observation evolved to the size E of ～ 6 × 10⁴⁰ erg that is one order larger than ever observed. They were long bursts (τ ≦ 600 s) of flat topped (trapezoidal) shape and those of exotic profiles. Those type II bursts exhibited some kinds of quasi-periodicities, which implies the vibrations or instabilities of the mass accretion onto the neutron stars. The type I bursts were often observed with/without type II bursts.     

Postural control responses sitting on unstable board during visual stimulation.

Concerning with the relation of vection induced by the optokinetic stimulation and the body movement, especially we attended to the neck joint movement, which counteracted to the shoulder movement. Then, we analyzed the mechanisms of the sitting postural control by using the seesaw board. By the optokinetic stimulation through the head mounted display (H.M.D.), the vection was leaded, and it affected to the sway of the body on the seesaw board. In this experiment, we found that the movement of upper part of body except for the head was the same direction to the seesaw board but the head moved out of phase to the seesaw board. This phenomenon will be suggested that the unstable condition of sway is balanced by the counter swing of head and the neck muscle tonus is controlled by acting of the vestibulo-collic reflex.