Kinematics of vertical climbing in lorises and Cheirogaleus medius.

The type of climbing exhibited by apes and atelines is argued to have been important in the evolution of specialized locomotion, such as suspensory locomotion and bipedalism. However, little is known about the mechanics of climbing in primates. Previous work shows that Asian apes and atelines use larger joint excursions and longer strides than African apes and the Japanese macaque, respectively. This study expands knowledge of climbing mechanics by providing the first quantitative kinematic data for vertical climbing in four prosimian species: three lorisid species (Loris tardigradus, Nycticebus coucang, and Nycticebus pygmaeus) that share with apes and atelines morphological traits arguably related to climbing, and a more generalized quadruped, Cheirogaleus medius. Subjects were videotaped as they climbed up a wooden pole. Kinematic values, such as step length and limb excursions, were calculated and compared between species. The results of this study show that lorises, like Asian apes and spider monkeys, use relatively larger joint excursions and longer steps than does C. medius during climbing. These data lend further support to the idea that some primate species (e.g., lorises, atelines, and apes) are more specialized kinematically and morphologically for climbing than others. Pilot data suggest that such kinematic differences in climbing style across broad phylogenetic groups may relate to the energetics of climbing. Such data may be important for understanding the morphological and kinematic adaptations to climbing exhibited by some primates.

Forelimb and hindlimb forces in walking and galloping primates.

One trait that distinguishes the walking gaits of most primates from those of most mammalian nonprimates is the distribution of weight between the forelimbs and hindlimbs. Nonprimate mammals generally experience higher vertical peak substrate reaction forces on the forelimb than on the hindlimb. Primates, in contrast, generally experience higher vertical peak substrate reaction forces on the hindlimb than on the forelimb. It is currently unclear whether this unusual pattern of force distribution characterizes other primate gaits as well. The available kinetic data for galloping primates are limited and present an ambiguous picture about peak-force distribution among the limbs. The present study investigates whether the pattern of forelimb-to-hindlimb force distribution seen during walking in primates is also displayed during galloping. Six species of primates were video-recorded during walking and galloping across a runway or horizontal pole instrumented with a force-plate. The results show that while the force differences between forelimb and hindlimb are not significantly different from zero during galloping, the pattern of force distribution is generally the same during walking and galloping for most primate species. These patterns and statistical results are similar to data collected during walking on the ground. The pattern of limb differentiation exhibited by primates during walking and galloping stands in contrast to the pattern seen in most nonprimate mammals, in which forelimb forces are significantly higher. The data reported here and by Demes et al. ([1994] J. Hum. Evol. 26:353-374) suggest that a relative reduction of forelimb vertical peak forces is part of an overall difference in locomotor mechanics between most primates and most nonprimate mammals during both walking and galloping.

Applying the marketing concept in health care: the no-show problem.

This article applies the marketing concept to the no-show problem in health care. The no-show problem at a hospital-based outpatient internal medicine clinic was analyzed to determine the determinants of no-show behavior. Two surveys were conducted: a patient questionnaire, and a telephone interview of patients that had recently missed an appointment. The surveys identified the lack of transportation as an important determinant of no-show behavior among the clinic's low-income and elderly patient population. The authors suggest that effective implementation of the marketing concept requires that health care organizations offer individualized transportation services to and from their facilities.