Abstract: Abstract  Traditional network research analyzes relational ties within a single group of actors: the models presented in this paper involve relational ties exist beteen two distinct sets of actors. Statistical models for traditional networks in which relations are measured within a group simplify when modeling unidirectional relations measured between groups. The traditional paradigm results in a one-mode socionatrix; the network paradigm considered in this paper results in a two-mode socionatrix; A statistical model is presented, illustrated on a sample data set, and compared to its traditional counterpart. Extensions are discussed, including those that model multivariate relations simultaneously, and those that allow for the inclustion of attributes of the individuals in the group.

Abstract: Hungry rats observed a conspecific demonstrator pushing a single manipulandum, a joystick, to the right or to the left for food reward and were then allowed access to the joystick from a different orientation. The effects of right-pushing vs left-pushing observation experience on (1) response acquisition, (2) reversal of a left-right discrimination, and (3) responding in extinction, were examined. Rats that had observed left-pushing made more left responses during acquisition than rats that had observed right-pushing, and rats that had observed demonstrators pushing in the direction that had previously been reinforced took longer to reach criterion reversal and made more responses in extinction than rats that had observed demonstrators pushing in the opposite direction to that previously reinforced. These results provide evidence that rats are capable of learning a response, or a response-reinforcer contingency, through conspecific observation.

Abstract: In summary, horses spend 60% or more of their time eating when grazing or when feed is available free choice. Grasses are their preferred food, but they supplement the grass with herbs and woody plants. Sweetened mixtures of oats and corn are the most preferred concentrate. Horses can increase or decrease the time spent eating and amount eaten to maintain caloric intake. Their intake is stimulated by drugs such as diazepam and by the presence of other horses. Horses stop eating when gastric osmolality increases; increases in plasma osmolality, protein, and glucose accompany digestion. Foals eat several times an hour and begin sampling solid food at the same time that their dam is eating. Several areas of particular importance to the equine industry have not been investigated. These areas include the effect of exercise on short- and long-term food intake and the influence of reproductive state on the feeding of mares.

Abstract: A direct enzyme immunoassay (EIA) for non-specific urinary progesterone (Po) metabolites, utilizing a non-specific monoclonal antibody against pregnanediol-3-glucuronide, was evaluated for the purpose of assessing luteal function in equids. Urinary pregnanediol-3-glucuronide (PdG) and immunoreactive PdG-like conjugate (iPdG) concentrations, indexed by creatinine, were compared to plasma Po concentrations in non-conceptive ovarian cycles through two ovulations in four mares. High-performance liquid chromatography (HPLC) of urine from lutealphase mares and a pregnant zebra revealed an absence of significant concentrations of PdG and the presence of at least three immunoreactive compounds, all of which were more polar than PdG. The concentration of iPdG in the mare ranged from a nadir of approximately 3 ng/mg Cr at the time of ovulation to nearly 400 ng/mg Cr at the mid-luteal-phase peak and paralleled plasma Po concentrations. This non-radiometric assay for iPdG permits the assessment of ovulation, luteal formation and function, and luteolysis in unprocessed urine samples from domestic mares. Data from a single zebra indicate this approach also will permit simplified and non-invasive longitudinal studies of ovarian function among a wide range of Equidae.