Ionospheric effects on the transmission of ultralow-frequency plasma waves.

Measurements of magnetospheric ultralow-frequency plasma waves (period tau, approximately 18 to 150 seconds) on the ground under continuous daylight conditions in the Antarctic and under alternate day-night solar illumination at the conjugate station in Quebec indicate a significant local time dependence in the transmission properties of the ionosphere for waves of these periods. When the Antarctic station is compared with the Quebec station, the tilt (with respect to the ionosphere) of the orientation plane of the waves is observed to be larger at local noon than at local night.

Correspondence (Infectiousness of neural cases)

While from the nature of things it is impossible to prove that patients whose lesions are of the bacteriologically negative, resistant type are under no circumstances able to trasmit leprosy, available evidence is against their being a source of danger to children, who are usually highly susceptible. With regard to the juvenile type, the frequency with which such cases suddenly develop widespread, bacteriologically positive lesions makes clear the necessity of keeping children suffering from this type of the disease under close observation, remembering the danger of their suddenly becoming actively infectious cases. THere is a tendency for advanced cutaneous-type cases to develop nerve lesions in the later stages of the disease. Patients seen at this stage are often classified as neural (properly, " secondary neural"). Routine bacteriological examination may at first fail to show Mycobacterium leprae, but repeated examination will often show clumps of acid-fast bacilli in the skin, nose or gums. Patients who have at one time suffered from widespread sutaneous leprosy with bacteriologically positive lesions should, even after the disease has become quiescent and arrested, be kept from close contact with healthy people and especially with children. Such contact should be permitted only when the disease has remained arrested for several years, when the patients have shown no signs of the disease on being subjected to the iodice test, and when all parts of the skin, nasal mucosa, gums, etc., have been carefully examined for bacteria and found negative. Reference is made to the use of the leprolin test in determining resistance to invasion by Myco. leprae and in judging the degree of danger of transmission of disease.