Simple nonrebreathing valves for use with large mammals.

Two simple nonrebreathing valves suitable for use with large mammals are described. These valves can be constructed in a reasonably well equipped workshop using materials that are readily available. The resistive pressure of both valves is less than 0.1 kPa at flow rates up to 15 L.s-1. Their main limitation is a relatively large dead space, although the dead space of valve B (290 mL) is less than the dead space of some commercially available valves. Healthy adult horses and cows compensate for the increased dead space by an increase in tidal volume.     

Psychophysical functions for perceived and remembered size

Separate groups of people estimated the sizes of perceived or of remembered objects. In three independent experiments, both sets of data were well fit by power functions, and the exponent was reliably smaller by remembered than for perceived size.