Improvements on the method for determining of 210Pb and 210Po in lead

An improved method is proposed to determine the content of 210Pb in lead using 210Po measured by alpha-ray spectrometry. This improved method, which is based on radiochemical separation by DDTC-toluene extraction, employs EDTA and citrate as masking reagents for the lead ions. To selectively extract polonium from an alkaline solution, the pH dependency was examined using a liquid scintillation counting method. And pH 9 was chosen as an extraction condition. Then 210Po was electrodeposited on a stainless steel disk, and the chemical recovery was followed by 209Po tracer. The effectiveness of the new method was validated by the agreement with the analytical results from five samples as determined by gamma-ray spectrometry. © 2010 Akadémiai Kiadó, Budapest, Hungary

Gap Effect for Manual Responses in Chimpanzees (Pan troglodytes): Temporal Aspects of Attentional Disengagement, Cognitive aging, and the Test for Attentional Bias Toward Infant Faces

This study examined factors influencing the gap effect, a phenomenon where the saccadic latency is faster when the fixation point disappears than when it overlaps with the target. The gap effect has been used in basic attentional research, as well as in developmental, neurophysiological, and comparative research. This effect is found not only in oculomotor tasks but also in manual response tasks in humans. In this study, we conducted a gap-overlap task using manual spatially orienting responses in chimpanzees and examined several factors that influence this effect. The results confirmed the gap effect for manual orienting responses in chimpanzees. Response times for gap trials showed a floor effect at around the gap with 200 ms and more. The duration of the fixation point did not affect the gap effect, although it did affect the chimpanzees’ response times. The presence or absence of auditory stimuli at the fixation point offset did not affect the gap effect. We also analyzed the data from two geriatric individuals (51 years old) who participated in this study and confirmed the usefulness of this effect for studying comparative cognitive-aging studies. In a second task we examined attentional bias for infant faces, an effect which has been reported in humans. However, while a gap effect was observed overall, there was no significant difference in the gap effect among stimulus types

Observation of Toroidal Flow on LHD

In order to investigate the formation of toroidal flow in helical systems, both NBI driven flow and spontaneous toroidal flow were observed in Large Helical Device (LHD). The toroidal flow driven by NBI is dominant in plasma core while its contribution is small near plasma edge. The spontaneous toroidal flow changes its direction from co to counter when the radial electric field is changed from negative to positive at plasma edge. The direction of the spontaneous toroidal flow due to the radial electric field near plasma edge is observed to be opposite to that in plasma core where the helical ripple is small