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Galloux, P., & Barrey, E. (1997). Components of the total kinetic moment in jumping horses. Equine Vet J Suppl, (23), 41–44.
Abstract: Thirty horses were filmed with a panning camera operating at 50 frames/s as they jumped over a 1.20 x 1.20 m fence. The markers of 9 joints on the horse and 7 joints on the rider were tracked in 2D with the TrackEye system. The centre of gravity and moment of inertia of each segment were calculated using a geometric algorithm and a cylindric model, respectively. The kinetic moment of each part of the horse was calculated after filtering, and resampling of data. This method showed the relative contribution of each body segment to the body overall rotation during the take-off, jump and landing phases. It was found that the trunk, hindlimbs and head-neck had the greatest influence. The coordination between the motion of the body segments allowed the horse to control its angular speed of rotation over the fence. This remained nearly constant during the airborne phase (120 +/- 5 degrees/s). During the airborne phase, the kinetic moment was constant because its value was equal to the moment of the external forces (722 +/- 125 kg x m2/s).
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Szenci, O., Palme, R., Taverne, M. A., Varga, J., Meersma, N., & Wissink, E. (1997). Evaluation of false ultrasonographic pregnancy diagnoses in sows by measuring the concentration of unconjugated estrogens in feces. Theriogenology, 48(5), 873–882.
Abstract: On Days 26, 28, and 30 after AI, ultrasonographic pregnancy diagnoses were performed on 207 gilts and sows by using a 3.5 MHz linear-array transducer. Fecal samples were taken from the rectum after each ultrasonographic examination, and the concentrations of unconjugated estrogens in selected samples (n = 73) were measured by RIA. Fecal unconjugated estrogen concentration of 11.7 ng/g feces or higher was indicative of pregnancy. The overall sensitivity and specificity of the ultrasonographic test was 99% for farrowing sows and 73.1% for nonfarrowing sows. With one exception, sows with a false negative diagnosis by ultrasonography on Day 26 were correctly diagnosed pregnant by elevated fecal unconjugated estrogens or repeated ultrasonographic examinations on Days 28 or 30. Return to estrus around the sampling period may cause false positive results in the unconjugated estrogen assay, while early embryonic mortality can result in false positive diagnoses in both the ultrasonographic test and estrogen assay. Although there was a positive correlation between the concentrations of unconjugated estrogens in the feces and litter size at farrowing in the selected sows, it seems very unlikely that fecal estrogens can provide an accurate tool for predicting litter size.
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Gallup, G. G. J. (1997). On the rise and fall of self-conception in primates. Ann N Y Acad Sci, 818, 72–82.
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Swartz, K. B. (1997). What is mirror self-recognition in nonhuman primates, and what is it not? Ann N Y Acad Sci, 818, 64–71.
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Parker, S. T. (1997). A general model for the adaptive function of self-knowledge in animals and humans. Conscious Cogn, 6(1), 75–86.
Abstract: This article offers a general definition of self-knowledge that embraces all forms and levels of self-knowledge in animals and humans. It is hypothesized that various levels of self-knowledge constitute an ordinal scale such that each species in a lineage displays the forms of self-knowledge found in related species as well as new forms it and its sister species may have evolved. Likewise, it is hypothesized that these various forms of levels of self-knowledge develop in the sequence in which they evolved. Finally, a general hypothesis for the functional significance of self-knowledge is proposed along with subhypotheses regarding the adaptive significance of various levels of self-knowledge in mammals including human and nonhuman primates. The general hypothesis is that self-knowledge serves as a standard for assessing the qualities of conspecifics compared to those of the self. Such assessment is crucial to deciding among alternative reproductive and subsistence strategies. The qualities that are assessed, which vary across taxa, range from the size and strength of the self to its mathematical or musical abilities. This so-called assessment model of self-knowledge is based on evolutionary biological models for social selection and the role of assessment in animal communication.
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Roberts, M. (1997).
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Shmidt Mech, L. D. (1997). Wolf pack size and food acquisition. Am Nat, 150.
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Judge, P. G., & De Waa, l F. B. M. (1997). Rhesus monkey behaviour under diverse population densities: coping with long-term crowding. Anim. Behav., 54(3), 643–662.
Abstract: A popular view is that high population density promotes behavioural pathology, particularly increased aggression. In contrast, according to a coping model, some primates have behavioural mechanisms (e.g. formal displays, reconciliation and grooming) that regulate social tensions and control the negative consequences of crowding. Seven captive rhesus monkey groups, Macaca mulattawere observed over a wide range of population densities where high-density groups were over 2000 times more crowded than low-density free-ranging groups. As density increased, male rhesus monkeys increased grooming and huddling but did not increase rates of aggression. Females increased all categories of behaviour examined (heavy aggression, mild aggression, formal bared-teeth displays, grooming and huddling), but the increases were not distributed uniformly to all classes of partners. Females increased only grooming, huddling and appeasement displays to males, increased only aggression and huddling with kin and increased all categories of behaviour to non-kin adult females. There were no differences in the percentage of aggressive conflicts reconciled across density conditions. Increased density had different effects on particular relationships. Relationships between females and males were characterized by a coping pattern in which animals modified their behaviour in ways that may decrease aggression under crowded conditions. Female relationships with kin and non-kin were characterized by increases in both aggression and friendly interactions as density increased. The different patterns of response to higher density may reflect different strategies depending on the strength and stability of relationships and the potential consequences if certain relationships are disrupted.1997The Association for the Study of Animal Behaviour
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Parr, L. A., Matheson, M. D., Bernstein, I. S., & De Waal, F. B. M. (1997). Grooming down the hierarchy: allogrooming in captive brown capuchin monkeys, Cebus apella. Anim. Behav., 54(2), 361–367.
Abstract: Observations of captive female brown capuchin monkeys in five groups revealed that grooming is primarily the occupation of dominant females at both the individual and dyadic levels. When categorized according to rank class, alpha females were the only class to perform significantly more grooming than they received. These results are inconsistent with reports on vervets, baboons and macaques, and suggest that grooming in capuchin monkeys may have different functions from those reported for cercopithecine primates. A dyadic analysis revealed, however, that grooming occurred more often between closely ranked females, similar to what is seen in several Old World monkey species. Therefore, some aspects of grooming in capuchins are similar to that seen in Old World monkeys, but the way they distribute grooming is different, which may prompt a re-evaluation of current theories regarding the social function of allogrooming in non-human primates.
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de Waal, F. B., & Seres, M. (1997). Propagation of handclasp grooming among captive chimpanzees. Am. J. Primatol., 43(4), 339–346.
Abstract: A grooming posture previously reported for two wild chimpanzee (Pan troglodytes) communities developed spontaneously in a captive group of the same species. This offered a unique opportunity to follow the propagation of a new social custom. The posture consists of two partners grasping hands--either both right hands or both left hands--and raising the arms in an A-frame above their heads while mutually grooming with their free hands. The propagation of this pattern was followed over a 5 year period. In the beginning, handclasps were always initiated by the same adult female. This female initiated the posture mainly with her adult female kin. In subsequent years, these relatives became frequent participants in the posture with each other as well as with nonrelatives. Over the years the posture increased in frequency and duration and spread to the majority of adults and also to a few adolescents and older juveniles. The pattern persisted after removal of the apparent originator.
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