The evolution of pelvic limb muscle moment arms in bird-line archosaurs.

Bipedal locomotion evolved along the archosaurian lineage to birds, shifting from "hip-based" to "knee-based" mechanisms. However, the roles of individual muscles in these changes and their evolutionary timings remain obscure. Using 13 three-dimensional musculoskeletal models of the hindlimbs of bird-line archosaurs, we quantify how the moment arms (i.e., leverages) of 35 locomotor muscles evolved. Our results support two hypotheses: From early theropod dinosaurs to birds, knee flexors' moment arms decreased relative to knee extensors', and medial long-axis rotator moment arms for the hip increased (trading off with decreased hip abductor moment arms). Our results reveal how, from the Triassic Period, bipedal theropod dinosaurs gradually modified their hindlimb form and function, shifting more from hip-based to knee-based locomotion and hip-abductor to hip-rotator balancing mechanisms inherited by birds. Yet, we also discover unexpected ancestral specializations in larger Jurassic theropods, lost later in the bird-line, complicating the paradigm of gradual transformation.

Gearing effects of the patella (knee extensor muscle sesamoid) of the helmeted guineafowl during terrestrial locomotion.

Human patellae (kneecaps) are thought to act as gears, altering the mechanical advantage of knee extensor muscles during running. Similar sesamoids have evolved in the knee extensor tendon independently in birds, but it is unknown if these also affect the mechanical advantage of knee extensors. Here, we examine the mechanics of the patellofemoral joint in the helmeted guineafowl Numida meleagris using a method based on muscle and tendon moment arms taken about the patella's rotation centre around the distal femur. Moment arms were estimated from a computer model representing hindlimb anatomy, using hip, knee and patellar kinematics acquired via marker-based biplanar fluoroscopy from a subject running at 1.6 ms-1 on a treadmill. Our results support the inference that the patella of Numida does alter knee extensor leverage during running, but with a mechanical advantage generally greater than that seen in humans, implying relatively greater extension force but relatively lesser extension velocity.

Health promotion in the office.

Occupational therapists have the training and skill to modify office environments in order to promote employee health. Minor changes in the ways tasks are performed can improve work performance, decrease the incidence of minor health complaints, and help prevent repetition injury. Two employee health promotion education programs are described. They were conducted by an occupational therapist and can be replicated in other settings. One program was a seven-session series for bank employees; the other was a luncheon presentation to office workers employed by a health science university.

A model for assessing health needs of the rural elderly: methodology and results.

The purpose of this health needs assessment of the rural elderly was to determine the actual conditions, opportunities, activities, and attitudes of older citizens living in a rural area and to assess their specific psychological, social, and medical needs. This was accomplished through a survey developed by an interdisciplinary team and distributed to individuals aged 55 years or older in a rural community of Georgia. Survey responses were used to plan and implement a series of four workshops to improve health education in the rural community surveyed. In addition, referrals to health care and social agencies were initiated where indicated.