A CdZnTe slot-scanned detector for digital mammography.

A new high-resolution detector has been developed for use in a slot-scanned digital mammography system. The detector is a hybrid device that consists of a CCD operating in time-delay integration mode that is bonded to a 150-microm-thick CdZnTe photoconductor array. The CCD was designed with a detector element pitch of 50 microm.

Solitary male chacma baboons in a desert canyon.

Solitary and paired adult (nine) and subadult (one) male chacma baboons, Papio ursinus, were observed over a period of years living in part of a wooded desert canyon not used by adjacent troops. These extratroop males were silent when alone and gave only one alarm vocalization, the "wa-hoo" call, when paired. The space occupied by them is unsuitable for use by troops according to criteria for adequate sleeping sites and access to water.

Baboon sleeping site preferences and relationships to primate grouping patterns.

Baboons choose sleeping sites in the following descending order of preference: (1) steep cliff faces and caves, (2) taller emerging trees in continuous forests, (3) the canopy of contiguous forest without emerging trees, and (4) open woodland trees. Choice of sleeping sites in an order appearing to agree with degree of inaccessibility to most predators suggests the hypothesis that predation avoidance is the major basis for use and choice of particular sleeping sites. If this preference order for kinds of sleeping sites is applicable to other large primates, it suggests that spacing of adequate sleeping sites relative to the distribution and density of food resources is one factor contributing to group size and possibly other features of primate social structure.

Starling Roost Dispersal and a Hypothetical Mechanism Regulating Rhthmical Animal Movement to and from Dispersal Centers.

A hypothetical mechanism is proposed that may regulate the dispersal pattern of animals aggregating at cores and dispersing from them into the surrounding terrain to forage. This hypothesis is that the number of individuals per unit of area in the space foraged by individuals using the same dispersal center declines with distance from the core, relaxing intraspecific competition for available resources, thereby compensating individuals that have ranged farther afield for the increased energy expenditure and time required to reach these more distant ranges. The compensation is the increased availability of resources due to reduced resource exploitation rates.