Biomedical subjects
Publications and source records attributed to E B Davies.
We defend pluralism in mathematics, and in particular Errett Bishop's constructive approach to mathematics, on pragmatic grounds, avoiding the philosophical issues which have dissuaded many mathematicians from taking it seriously. We also explain the computational value of interval arithmetic.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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The survival of Aujeszky's disease (pseudorabies) virus outside the living host was found to be dependent on pH level and temperature. Virus inactivation occurred at a rate varying from 0.04 log10 per day at 4 degrees C to 0.6 log10 per day at 37 degrees C at the optimum pH levels of 6 to 8. Fluctuation of the temperature between 4 degrees C and 37 degrees C had no apparent effect upon the titre of the virus. At a steady temperature of -13 degrees C, the virus was rapidly inactivated at all tested pH levels. For long-term storage it is recommended that the pH should be adjusted to between 6 and 7, that suspensions should be kept at -90 degrees C and that freezing and thawing should be rapid so as to pass through the just subzero temperature zone as quickly as possible. Drying, both on glass and on gelatin, caused inactivation of the virus at all pH levels, as did exposure to ultraviolet light.
Pseudorabies virus was shed by a sow that had been clinically infected 19 months earlier (when 1 month old) and had been in isolation for 3 1/2 months. The shedding was detected from the third to eighth days after farrowing and was confined to the nasal secretion. Two susceptible pigs in contact with the sow after farrowing were not infected.
The persistence of pseudorabies virus (PRV) in pigs clinically recovered from the disease was detected by culture of tissue fragments. Weanling pigs were infected by intranasal instillation of 200,000 plaque-forming units of a strain of PRV isolated from sick pigs in Iowa, and virus was recovered from them 6 weeks to 13 months later. Tonsil, trigeminal ganglia, or pooled trigeminal ganglia and olfactory and optic nerve tissue were most consistently the source of virus. The tissue-fragment culture technique was compared with a co-culture technique for detection of virus in tissue specimens from the recovered pigs. Use of these procedures provided the means to detect PRV in pigs for periods longer than previously recognized.
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