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  • 1
    ISSN: 1572-9591
    Keywords: Helical plasma experimental device ; fusion ; radiation monitoring ; natural radiation ; X- and γ-rays detection ; neutron detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract For experiments with the Large Helical Device (LHD) which is now under construction at the Toki site in Japan, radiation safety issues were discussed. In the course of plasma experiments, radiations such as X-rays, induced γ-rays, and neutrons increase. From a safety point of view, these radiation exposures to the environment should be controlled to limit the annual dose to less than 50 μSv at the site boundary. In order to meet this, an area monitoring system named RMSAFE (Radiation Monitoring System Applicable to Fusion Experiments) has been developed and partly installed. This can discriminate and measure radiations including burst-like emissions due to plasma shots from natural radiations. For the present period, this system is operating to monitor the natural radiation levels before the LHD operation. It was observed that the radiation levels strongly depend on rain levels and ground state. An indoor area monitoring system has already been implemented on site, to measure radiations from NBI and ECH test shots, and it shows good monitoring ability. Also, thermoluminescence dosimetry has been applied. The importance of investigating the radiological behavior under natural conditions with continuous monitoring is shown.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 46 (1982), S. 292-300 
    ISSN: 1432-1106
    Keywords: Ventromedial nucleus ; Hypothalamus ; Antidromic activation ; Central gray ; Midbrain ; Amygdala
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In female rats anesthetized with urethane, 151 neurons in and around the ventromedial nucleus of the hypothalamus were identified by antidromic activation as having axonal projection to the mesencephalic central gray at the midcollicular level. Identified neurons were most numerous in the rostral part and at the borders of the nucleus. Antidromic spike latencies, constant for a given cell to stimulation with fixed intensity at a low repetition rate, had a wide range across cells (1.4–41.5 ms). In 37 cells, gradual increases in stimulus intensity allowed sudden discrete latency decreases as large as 9.8 ms. These may reflect activation of separate axonal branches of terminal arborizations. Eleven among 43 tested cells were antidromically driven from the dorsal longitudinal fasciculus (DLF) at the diencephalic-mesencephalic junction as well as from the central gray. Latencies of DLF responses were always shorter than those from central gray. From this and collision experiments between central gray-evoked and DLF-evoked antidromic spikes, it was concluded that at least one quarter of mesencephalic projections from the ventromedial nucleus descend through DLF. The mean conduction velocity of these axons was 0.8 m/s, indicating that they belong to thin unmyelinated C-group fibers. Thirty percent of the cell population studied received excitatory input from the cortical or medial nucleus of the amygdala. Four cells were identified as having projections both to the central gray and the amygdala. Estrogen treatment of ovariectomized female rats caused no major changes in antidromic latency, absolute refractory period or resting activity of these identified hypothalamic neurons. However, the stimulation threshold for antidromic activation was significantly lower in the estrogen-treated animals. Axons to the central gray from ventromedial hypothalamic neurons provide for hypothalamic bias on brain stem reflex paths, for reproductive and other behaviors.
    Type of Medium: Electronic Resource
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