The first of these questions is in the province of sensory physiology, and is the only one for which appreciable understanding has been achieved. This article will be concerned primarily with the second and third questions, which are still subject to a vast amount of speculation, and where the few relevant facts currently supplied by neurophysiology have not yet been integrated into an acceptable theory. With regard to the second question, two alternative positions have been maintained. The first suggests that storage of sensory information is in the form of coded representations or images, with some sort of one-to-one mapping between the sensory stimulus

The transit of a star by a dark companion or planet results in a characteristic colorimetric “signature,” which should be detectable by photometric means. This signature, which is due to differential limb darkening in red and blue light, takes the form of a slight shift towards the blue as the planet crosses the limb of the star, followed by an abnormal reddening during the transit of the center region of the star, and finally another shift towards the blue as the planet approaches the far limb. An analysis of this signature, the probabilities of detecting such transits (using the solar system as a model), and possible instrumentation for this purpose are discussed. A system designed to yield one or more planetary detections per year is believed to be feasible at moderate cost. Such a system would consist of three wide-field telescopes, at well-separated sites, slaved to a central computer. Each telescope would be equipped with a two-color photometer employing an image dissector under computer control for tracking and rapid switching between program stars without requiring frequent resetting of the instrument. Each telescope would survey an independent sample of stars on a rapid rotation cycle, until one of the telescopes detected an unusual transient, at which time all three would be used to provide additional data and increased reliability as a coincidence detection system.

A questionnaire submitted to 1059 students and faculty at Cornell University revealed general agreement (84%) on the desirability of limiting family size although 65% wanted 3 children or more. About half favored the pill over all available means. Voluntary sterilization was favored by only 6% males and 2% of the females. A majority (52% of males and 61% of females) said they would never undergo sterilization. Biologists and nonbiologists graduate students and freshmen were equally uninformed about sexual sterilization.

Induction of behavior by chemical extracts of trained rat brain has been observed in two types of choice situations. (1) In a symmetric (left/right) choice situation, the induced bias may be either positively or negatively related to that learned by the donors, depending strongly upon dosage and the exact experimental conditions. This makes the effect unstable and difficult to replicate with this procedure. Inversion effects appear to predominate in the observed dosage range. (2) In an asymmetric (two-chamber) choice situation, differing in operant tasks, wall colors, and other cues, a consistently positive effect with a simpler dose dependence was observed. The difference between these two cases is attributed to the lack of specific stimuli identifying the behavioral choices in the symmetric situation, and the abundance of specific stimulus cues in the asymmetric case.

The lack of myostatin promotes growth of skeletal muscle, and blockade of its activity has been proposed as a treatment for various muscle-wasting disorders. Here, we have examined two independent mouse lines that harbor mutations in the myostatin gene, ...

The performance of successfully landing an airplane is generally supposed to be dependent on the ability to perceive visual depth and distance, or more generally space. The classical explanation of human ability to see space is that the eye provides a set of cues to the distance of a given object, and likewise differential cues to the different distances of different objects. Such cues, include (a) binocular parallax or disparity, (b) linear perspective, including the apparent size of objects whose real size is known, (c) aerial perspective, superposition, shading, and (d) motion parallax, i.e. the apparent movement of physically stationary objects relative to one another and to the observer. The last depends upon motion of the observer, usually locomotion, and the strength of the effect is in proportion to the velocity of the observer. Consequently it ought to be of particular significance for spatial judgments during aircraft landings, in which locomotion occurs at a considerabe velocity. The aim of this report is: (1) to examine the existing definitions of motion parallax; (2) to show that they are not sufficiently general to cover the visual situation during aircraft landing; (3) to formulate geometrically a somewhat different principle (called motion perspective); and (4) to apply this general principle to the problem of perceiving the ground and one's relation to it during descent.