Disc cone antenna for 7 MHz. Scheme, description

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Disc cone antenna for 7 MHz. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / HF antennas

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The antenna is inferior to a dipole in short-range communications, but significantly outperforms it in long-range QSOs. The bandwidth at 7 MHz is about 500 kHz. It can be recommended for operation on higher frequency ranges both in this form and in the calculated single-range form.

Disc cone antenna for 7 MHz

The antenna is powered by a 50-ohm cable at the connection point of the upper central insulator: the central core of the cable to the upper horizontal dipole, and the braid to the lower V-shaped one.

Author: Viktor Kholod, Grayvoron; Publication: N. Bolshakov, rf.atnn.ru

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Memory depends on the time of day 21.12.2019

If you're trying to remember something and you can't, don't get discouraged - try to stretch your memory at other times of the day, and, quite possibly, you will remember everything you need

Researchers from the University of Tokyo and Tokyo Agricultural University showed mice different objects to remember them, and then, after some time, observed how well the mice remembered them. If the mouse studied the subject for a short time, it means that it remembered it quite well, and if it took a long time, it means that it managed to forget it. The objects were shown to mice just before when the animals usually wake up (that is, in the evening, because mice are nocturnal animals), and their memory was checked either a day later, that is, again before natural awakening, or immediately after the mice usually went to sleep (that is, eat very early in the morning). In the first case, when a day passed between acquaintance with a new thing and remembering, the mice did not remember it well; in the second case, when the thing was shown to them after they were supposed to fall asleep (but they showed it, of course, to awake mice), they remembered it well. The same results were obtained when it was necessary to get acquainted not with an inanimate object, but with another mouse.

But the experiment was set up not only with ordinary mice, but also with mutant mice in which the BMAL1 gene did not work. This is one of the main genes that control circadian rhythms: the level of the BMAL1 protein changes during the day, and as it changes, it turns on or off many other genes. (You can learn more about it in one of our articles.) In general, mice with BMAL1 turned off forgot and remembered in exactly the same way, only they forgot more strongly - when a familiar object or mouse was shown to them a day later, they clearly remembered them worse than normal animals with working BMAL1. That is, firstly, memory clearly depended on the time of day, which neuroscientists have suspected for a long time, and, secondly, memory processes depended on an influential clock gene.

The clock protein BMAL1 stimulated the work of dopamine receptors and modified a number of signaling molecules in one of the zones of the hippocampus, which, as we know, is one of the main brain memory centers. Perhaps, using the signaling pathways that are affected by the BMAL1 gene, it will be possible to create some kind of memory enhancer. Although why memory is subject to circadian rhythms at all remains a mystery - it is possible that this is simply a side effect of the circadian rhythms.

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