A simple method for the production of homogeneous water drops down to 1 micron radius

The enigma of olfactory learning revisited

If, as indicated in olfactory conditioning studies, rats are able to demonstrate primate-like behavior by their acquisition of response strategies, rodent olfactory learning may provide a particularly useful model for neurobiological analyses of learning and memory. Reid and Morris [Proc. R. Soc. Lond., Ser. B 247, 137-143 (1992); Trends Neurosci. 16, 17-20 (1993)] have recently challenged these views. They suggested that the evidence for acquisition of an olfactory learning set in rodents is insufficient and that rat olfactory learning may provide no special advantage for the neurobiologist. This essay reviews the relevant studies and concludes that there are serious shortcomings in the Reid and Morris argument, that the available data base provides clear evidence for the claim that rats acquire abstract rules for responding and that olfactory learning may be qualitatively different from other forms of instrumental learning in rodents.

Water-to-air transfer of virus

Bubbles rising through suspensions of the bacteriophages T2 and T4 and of Escherichia coli adsorb and eject these particles in droplets that are formed when the bubbles burst. The concentration of the viruses in ejected droplets, determined from electron microscopy, exceeded the suspension concentration by 50 times. Similar results were obtained for Escherichia coli. The viability of some of the adsorbed particles was established by biological counts.

Olfactory stimulus control evaluated in a small animal olfactometer

A fully automated air-stream olfactometer and test chamber are described. Studies with rats using a discrete trials, go, no-go training procedure demonstrate that olfactory discriminations are acquired rapidly and, under appropriate conditions, with few or no errors. During training, the rat makes an easily measured stimulus sampling response on each trial (sniffing at the air inlet port). Sampling duration varies with problem difficulty and provides a valuable adjunctive measure of discrimination behavior.

Mechanism for the water-to-air transfer and concentration of bacteria

Air bubbles breaking at the air-water interface can remove bacteria that concentrate in the surface microlayer and eject the bacteria into the atmosphere. The bacterial concentrations (numbers per milliliter) in the drops ejected from the bubbles may, depending on drop size, be from 10 to 1000 times that of the water in which the bubbles burst.