INTRINSIC OPTICAL SIGNAL IMAGING OF RETINAL ACTIVITY IN FROG EYE

Using a near-infrared(NIR)light flood-illumination imager equipped with a high-speed(120 Hz)CCD camera,we demonstrated optical imaging of stimulus-evoked retinal activity in isolated,but intact,frog eye.Both fast and slow transient intrinsic optical signals(IOSs)were observed.Fast optical response occurred immediately after the stimulus onset,could reach peak magnitude within 100 ms,and correlated tightly with ON and OFF edges of the visible light stimulus;while slow optical response lasted a relatively long time(many seconds).High-resolution images revealed both positive(increasing)and negative(decreasing)IOSs,and dynamic optical change at individual CCD pixels could often exceed 10%of the background light intensity.Our experiment on isolated eye suggests that further development of fast,high(sub-cellular)resolution fundus imager will allow robust detection of fast IOSs in vivo,and thus allow noninvasive,three-dimensional evaluation of retinal neural function.

Timing analysis of the black hole candidate EXO 1846–031 with Insight-HXMT monitoring

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.