Schofield memorial lecture. Bull semen and muscle ATP: some evidence of the dawn of medical science in ancient Egypt.

The importance of animal experimentation to human and animal health is not well understood by an increasingly articulate segment of the public. This could have very unfortunate consequences for man and his domestic animals. Even veterinarians and physicians are not as conversant as they need be about the great extent to which advances in human health have depended upon animal observations and experiments. Some believe that resort to "animal models" of biomedical phenomena, including diseases--a comparative or analogical approach to medical studies--is a relatively recent event. Even medical historians often treat these subjects as occasionally recurring aberrations which began with the Greeks, thus largely overlooking the historical meaning and continuing importance of "one medicine" irrespective of species. In fact, comparative medicine has probably been basic to medical progress ever since the dawn of a medical science. Recent research indicates that this approach to biomedical mysteries began to evolve in the minds of Egypt's healer-priests long before Aristotle and the later Alexandrian Greeks made the whole process explicit. Here we examine the origins of what were possibly the first two biomedical theories profounded from inferences based upon dissections, confirmed in at least one instance by experiment, and then applied to medical practice.     

Braconidae (Hymenoptera) associated with forest and ornamental trees and shrubs in Israel

Data are presented on the occurrence of Braconidae (Hymenoptera parasitica) parasitizing insects associated with forest and ornamental trees and shrubs in Israel. Fifty-five genera of plants are listed, the richest in braconid fauna being tamarisk (9 species); acacia, pistachio and poplar (8 species each); carob and oak (7 species each). Of the 95 species of insect hosts mentioned, 53 are Lepidoptera, mostly Gelechiidae (7 species), Pyralidae (6 species), Noctuidae (5 species), Gracillariidae, Tortricidae, Geometridae, Lymantriidae and Lycaenidae (3 species each); 44 are Coleoptera, mostly Cerambycidae (13 species), Scolytidae (12 species), and Bostrichidae (9 species); three are Diptera. Of the 92 species of braconids listed, of which only 65 have been fully named, 56 develop in Lepidoptera, mostly Noctuidae (15 species), Gelechiidae (11 species) and Pyralidae (9 species); 33 species develop in Coleoptera, mostly Cerambycidae (12 species, Bostrichidae (10 species) and Scolytidae (5 species); and three species develop in Diptera. Thirty-eight species are new to the fauna of Israel; at least three of them are new to science,viz., Gnaptodon, Gildoria andDendrosotinus titubatus Papp.     

The effect of some benzoyl phenylureas on the larvae of earias insulana

Diflubenzuron, PH 60-38, PH 6043, penfluron (PH 60-44), PH 6045, triflumuron, chlorfuazuron (IKI-7899), teflubenzuron (CME 134), XRD473 and Dowco 439 were tested for their efficacy against the larvae of the spiny bollworm,Earias insulana (Boisd.), in laboratory experiments. The compounds were incorporated at different concentrations in an artificial diet and 5-day-old larvae were introduced and grown on the treated diets until pupation and adult emergence. Teflubenzuron was active at 0.1 ppm, chlorfuazuron at 0.75 ppm and PH 60-38 at 10 ppm; triflumuron and diflubenzuron were active only at 50 ppm; all the rest of the compounds were even less active. When cotton bolls were dipped in teflubenzuron and offered to 6-day-old larvae in the laboratory, only 4% and 10% of the larvae penetrated inside the bolls treated with 50 and 25 ppm a.i., respectively, whereas 68% penetrated inside untreated bolls.     

Spring invasion of Heterodera schachtii in sugarbeet; a simulation study

A simulation model was developed for the spring invasion of the beet cyst nematode,Heterodera schachtii Schmidt, into sugarbeet roots, according to the state variable approach. This model describes the processes of egghatch, emergence of second stage larvae from cysts, migration to roots and penetration into roots quantitatively, using published data.In 1983 a field experiment was conducted to test this model.H. schachtii cysts were introduced at depths 6–29 cm in PVC-cylinders, buried in the soil. The rooting depth of sugarbeet seedlings, growing in these cylinders, was limited to 5 cm by 50 m mesh nylon gauze. Every 10 days the second stage larvae, which had penetrated into the roots of these seedlings were counted. After 50 days, about 40% of the eggs had hatched. More than 20% of the emerged larvae penetrated if the cysts had been buried undeeply, and only 4% if the cysts had been buried at 29 cm depth.The model predicted the course of penetration into the root during the first 40 days with reasonable accuracy (r²=0.79), but in the 5th period of 10 days the model made an overestimation of more than 100%. Egghatch after 50 days was correctly simulated. The differences in penetration into the root between the model and the experiment might result from an oversimplified simulation of the penetration success or the neglection of mortality of second stage larvae. Detailed experiments should be done to provide better parameters for these factors.Samenvatting Volgens de toestandsvariabele-benadering werd een simulatiemodel ontwikkeld van de voorjaarspenetratie van het bietecystenaaltje. Het model beschrijft aan de hand van literatuurgegevens het uikomen van de eieren, het verlaten van de cyst door de larven, de migratie naar en de penetratie in de wortel.In 1983 werd een veldproef uitgevoerd om het model te toetsen. Cysten vanH. schachtii werden op 5 dieptes tussen 6 en 29 cm ingegraven in PVC-cylinders, welke waren verzonken in de bodem. De bewortelingsdiepte van de suikerbiete-zaailingen die hierin groeiden werd beperkt tot 5 cm door nylon gaas van 50 m maaswijdte. Elke 10 dagen werden de larven geteld die in de wortels van deze plantjes waren gepenetreerd. Na 50 dagen was 40% van de eieren uitgekomen. Meer dan 20% van de gelokte larven penetreerden als de cysten ondiep waren ingegraven, en slechts 4% als de cysten op 29 cm diepte waren ingegraven.Gedurende de eerste 40 dagen werd het verloop van de penetratie in de wortel met redelijke nauwkeurigheid door het model voorspeld (r²=0.79). In de 5e periode van 10 dagen maakte het model echter een overschatting van meer dan 100%. Het uitkomen van de eieren werd correct gesimuleerd. De verschillen in penetratie tussen het model en de proef zouden het gevolg kunnen zijn van een oververeenvoudigde simulatie van het penetratiesucces of van het verwaarlozen van de mortaliteit van de migrerende larven. Betere gegevens hierover zullen moeten komen uit detailproeven.     

What makes a good computer device?

Numerous development projects aimed at replacing the silicon technology that dominates computer logic with a faster alternative have been conducted throughout the past 25 years. None has succeeded. The alternatives are usually based on a device that switches very rapidly, and they neglect many other requirements of computer logic. In this article the essential physical factors that account for the success of transistors in digital applications are identified, as are the factors that are absent in proposed alternative devices.     

Recurring origins of allopolyploid species in asplenium

A large proportion of plant species has originated through allopolyploidy: interspecific hybridization followed by chromosome doubling. Heterozygosity remains fixed in allopolyploids because of nonsegregation of parental chromosomes. Two allotetraploid species of the fern genus Asplenium show allozyme polymorphisms at loci that are polymorphic in their diploid progenitors, indicating that each has originated more than once and implicating continued gene flow from diploids to tetraploids.