Olfactory system volume

SFE is carried out above the solvent critical point, and the properties of a supercritical fluid depend on pressure and change along with its density. These criteria determine the selectivity of the extraction medium. One fluid can therefore be used to extract a whole series of compound groups (depending on the pressure in the system, the temperature, extraction medium volume flow, and extraction time) and to separate the obtained extract into appropriate fractions. Selective fractionation is used, for example, to separate olfactory and gustatory substances in the extraction of hops for beer production. 

Single-component pheromone A pheromone which naturally contains either otie component or a closely related set of redundant components which function as a single entity (are encoded by a common neural pathway associated with a single olfactory receptor or set of related receptors). Such compounds are expected to have considerable biological activity regardless of the background odor they might be tested in. However, under certain circumstances (e.g. presence of the odor of a predator see Smith, this volume) their effects may be overridden by the central nervous system in the presence of other stimuli. Their activity should be comparable to the natural odor itself. 

Discussions of allometry (e.g., Schmidt-Nielsen, 1984) focus on the mechanical consequences of size differences. The skeletal system changes with increased size because of the added stress of increased weight. The heart increases with size because of the increased demands of pumping a greater volume of blood. In these examples, the functional consequences of scaling seem obvious. When the number of receptor neurons contributes to the performance of a sensory system, the effect of changes in size seem less clear. This conundrum had not escaped earlier researchers who wondered how adult humans, with an olfactory epithelial surface area of lOcm, are considered microsmatic while a rabbit, with 9.3cm of olfactory epithelium are considered macrosmatic (Moulton and Beidler, 1967). 

The olfactory stimulator can be controlled by digital electronics. Many different rates, intensities, and combinations of airborne materials can be presented by a mere keystroke. Moreover, because the system can easily dispense volumes as small as a few himdred pi of fluid, they can provide exquisitely fast and precise olfactory inputs near the threshold of human olfaction. A small version of the device can be used with laboratory animals (44). 

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