RE: Resurrection of the New Papers - correction

[Tim Williams <twilliams_alpha@hotmail.com>]

Citation for Tobalske and Dial (2007) is Journal of Experimental Biology 
210: 1742-1751.


> Tobalske, B.W. and Dial. K.P. (2007).  Aerodynamics of wing-assisted 
> incline running in birds.
>
> Summary: "Wing-assisted incline running (WAIR) is a form of locomotion in 
> which a bird flaps its wings to aid its hindlimbs in climbing a slope.  
> WAIR is used for escape in ground birds, and the ontogeny of this behavior 
> in precocial birds has been suggested to represent a model analogous to 
> transitional adaptive states during the evolution of powered avian flight.  
> To begin to reveal the aerodynamics of flap-running, we used digital 
> particle image velocimetry (DPIV) and measured air velocity, vorticity, 
> circulation and added mass in the wake of chukar partridge _Alectoris 
> chukar_ as they engaged in WAIR (incline 65?85°; N=7 birds) and ascending 
> flight (85°, N=2).  To estimate lift and impulse, we coupled our DPIV data 
> with three-dimensional wing kinematics from a companion study.  The 
> ontogeny of lift production was evaluated using three age classes: baby 
> birds incapable of flight [6?8 days post hatching (d.p.h.)] and volant 
> juveniles (25?28 days) and adults (45+ days).  All three age classes of 
> birds, including baby birds with partially emerged, symmetrical wing 
> feathers, generated circulation with their wings and exhibited a wake 
> structure that consisted of discrete vortex rings shed once per downstroke. 
>  Impulse of the vortex rings during WAIR was directed 45±5° relative to 
> horizontal and 21±4° relative to the substrate.  Absolute values of 
> circulation in vortex cores and induced velocity increased with increasing 
> age.  Normalized circulation was similar among all ages in WAIR but 67% 
> greater in adults during flight compared with flap-running.  Estimated lift 
> during WAIR was 6.6% of body weight in babies and between 63 and 86% of 
> body weight in juveniles and adults. During flight, average lift was 110% 
> of body weight.  Our results reveal for the first time that lift from the 
> wings, rather than wing inertia or profile drag, is primarily responsible 
> for accelerating the body toward the substrate during WAIR, and that 
> partially developed wings, not yet capable of flight, can produce useful 
> lift during WAIR.  We predict that neuromuscular control or power output, 
> rather than external wing morphology, constrain the onset of flight ability 
> during development in birds."
>
>
> Rubenson, J., Lloyd,  D.G., Besier, T.F., Heliams, D.B., and Fournier, P.A. 
> (2007). Running in ostriches (_Struthio camelus_): three-dimensional joint 
> axes alignment and joint kinematics.  Journal of Experimental Biology 210: 
> 2548-2562.
>
> Summary: "Although locomotor kinematics in walking and running birds have 
> been examined in studies exploring many biological aspects of bipedalism, 
> these studies have been largely limited to two-dimensional analyses.  
> Incorporating a five-segment, 17 degree-of-freedom (d.f.) kinematic model 
> of the ostrich hind limb developed from anatomical specimens, we quantified 
> the three-dimensional (3-D) joint axis alignment and joint kinematics 
> during running (at ~3.3 m s?1) in the largest avian biped, the ostrich.  
> Our analysis revealed that the majority of the segment motion during 
> running in the ostrich occurs in flexion/extension.  Importantly, however, 
> the alignment of the average flexion/extension helical axes of the knee and 
> ankle are rotated externally to the direction of travel (37° and 21°, 
> respectively) so that pure flexion and extension at the knee will act to 
> adduct and adbuct the tibiotarsus relative to the plane of movement, and 
> pure flexion and extension at the ankle will act to abduct and adduct the 
> tarsometatarsus relative to the plane of movement.  This feature of the 
> limb anatomy appears to provide the major lateral (non-sagittal) 
> displacement of the lower limb necessary for steering the swinging limb 
> clear of the stance limb and replaces what would otherwise require greater 
> adduction/abduction and/or internal/external rotation, allowing for less 
> complex joints, musculoskeletal geometry and neuromuscular control.  
> Significant rotation about the joints' non-flexion/extension axes 
> nevertheless occurs over the running stride.  In particular, hip abduction 
> and knee internal/external and varus/valgus motion may further facilitate 
> limb clearance during the swing phase, and substantial 
> non-flexion/extension movement at the knee is also observed during stance.  
> Measurement of 3-D segment and joint motion in birds will be aided by the 
> use of functionally determined axes of rotation rather than assumed axes, 
> proving important when interpreting the biomechanics and motor control of 
> avian bipedalism."
>
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