Concord Field Station

David Lentink

Phone: +1-781-275-1725 extension 108

Research interests: I study swimming and flight in nature and use my understanding of how animals and plants move through water and air as an inspiration for designing micro vehicles.

At the Concord Field Station I study how birds are able to keep their balance during manoeuvering flight. In this study I try to understand what the control demands are for the birds' motor and sensory apparatus to fly stable and manoeuvre well. My goal is to combine theoretical and experimental techniques to find out how flight mechanics, aerodynamics, muscle physiology and the sensor modalities together mediate flight stability and manoeuvrability.

I am also affiliated with the Experimental Zoology Group at Wageningen University, where I am an assistant professor working on fish swimming, the flight of birds (swifts and hummingbirds), insects (flies) and autorotating seeds (maple seeds). My insect flight research has inspired me to develop a flapping micro air vehicle and a morphing micro plane together with bachelor students.

Recent publications:
Lentink, D.; Müller, U.K.; Stamhuis, E.J.; Kat, R. de; Gestel, W.J.H. van; Veldhuis, L.L.M.; Henningsson, P.; Hedenström, A.; Videler, J.J.; Leeuwen, J.L. van (2007). How swifts control their glide performance with morphing wings. Nature 446, 1082 - 1085.

Allison Arnold

Research interests: I use computer models of the musculoskeletal system, together with experimental data, to study the functions of muscles during human and animal locomotion. For example, I have analyzed simulations of walking to investigate why some children with cerebral palsy walk with excessive stance-phase hip flexion, while others walk with diminished swing-phase knee flexion. Before such models can be used clinically to plan treatments for patients, however, the accuracy of existing models must be further tested and improved.

With collaborators at the Concord Field Station, I am:

• creating computer simulations that characterize the bone geometry, joint kinematics, mass and inertial characteristics, and muscle moment-generating properties (i.e., architecture and moment arms) of the hindlimb of a goat.
• comparing predictions of the simulations to in vivo and in situ measurements of muscle-tendon forces, length changes, and EMG activity.

Our goal is to refine estimates of muscle forces generated from Hill-type models, and to verify muscle excitation patterns generated from optimization approaches such as computed muscle control. This work will also enable novel comparative studies of the actions of muscles during bipedal and quadrupedal locomotion.

Recent publications:
Arnold, Thelen, Schwartz, Anderson, and Delp (2007). Muscular coordination of knee motion during the terminal swing phase of gait. Journal of Biomechanics, 40:3314-3324.
Arnold, Schwartz, Thelen, and Delp (2007). Contributions of muscles to terminal-swing knee motions vary with walking speed. Journal of Biomechanics, 40:3660-3671.
Delp, Anderson, Arnold, Loan, Habib, John, and Thelen (2007). OpenSim: open-source software to create and analyze dynamic simulations of movement. IEEE Transactions on Biomedical Engineering, 54(11):1-11.

Chris Richards

Research interests: I explore how aquatic creatures control their swimming performance. Swimming frogs are ideal models because their behavior is highly plastic: they cruise, dart, glide and turn with speeds ranging from lazy to explosive. What are the various patterns of leg motion that cause these differences in performance? What can the time-varying hydrodynamic forces on the frog's body and feet tell us about the work and power required from the leg muscles? How does the underlying neuromuscular system dynamically shift to enable this range of behavior? I use a combination of in vivo and in vitro muscle techniques as well as mathematical modeling to address these questions.

Recent publications:
Richards, C. T. and Biewener, A. A. (2007). Modulation of in vivo muscle power output during swimming in the African clawed frog (Xenopus laevis). J. Exp. Biol. 210, 3147-3159.

Carlos Moreno

Research interests: I am interested in characterizing and evaluating musculoskeletal performance in terrestrial mammals during nonsteady behaviors such as accelerating, decelerating, turning and dodging. To achieve this, I have developed portable data logging instruments to record data from animals running and turning freely in the field. I will first use force plates to characterize the mechanics of turning 90 degree corners, then collect inertial sensor data to quantify performance of natural turning movements. Finally, I will combine these techniques with in vivo muscle strain and activation measurements in order to investigate muscle function during rigorous movements such as dodging and turning.

Recent publications:
Moreno, C. A., Main, R. P. and Biewener, A. A. (2008). Variability in forelimb bone strains during non-steady locomotor activities in goats. J. Exp. Biol. 211(7), 1148-1162.

Angela M. Berg

Angie's webpage

Research interests: My primary research interest is in bird flight, especially understanding how birds move their wings to effect different modes of flight. In my first project, I used high-speed video to explore the differences among ascending, level, and descending flight (Berg & Biewener, in press). Now I am continuing work on landing and takeoff flight, with a combination of high-speed video and in vivo muscle measurements. I plan to use DPIV (digital particle image velocimetry) to further study how landing flight is distinct from normal level flight. In addition to my aerodynamic projects, I will be studying the comparative morphology of wings and evaluating the connection between wing morphology and muscle morphology across species.

Recent publications:
Berg, A. M. and Biewener, A. A. (2008). Kinematics and power requirements of ascending and descending flight in the pigeon (Columbia livia). J. Exp. Biol. 211(7), 1120-1130.

Edwin Yoo

Research interests: I am interested in climbing mechanics in goats and the biomechanics of horn impacts during head butting behaviors. I employ experimental approaches as well as finite-element analysis to investigate the consequences of these behaviors on bone and horn design.

Carolyn Eng

Research interests: I am broadly interested in muscle physiology and factors affecting the behavior of muscle in vivo. Specifically, I am interested in the development, plasticity, and functional relevance of muscle architecture and its contribution to dynamic muscle function.
Currently, I am performing experiments to examine where on the muscle length-tension curve various muscles in the guinea fowl hindlimb operate under various conditions. Using the operating range as a functional measure, I can examine the factors which influence this property before tracing it down to the sarcomere level. This experiment also allows me to examine the role of muscles and tendons in contributing to muscle-tendon unit and joint movement and work in a unique biarticular muscle.
Tangentially, I am also interested in muscle-tendon dynamics during human movement. I would like to further examine the role of tendon elastsic energy storage during human walking and examine this in the context of the evolution of bipedalism.

Ivo Ros

I am interested in dynamical systems such as flight. Because of the apparent ease with which some of nature's members fly, one might easily overlook the convoluted synergy of the processes involved. Investigating complex phenomena requires a combination of multiple approaches. In the field of biomechanics, the topics involved in flight of particular interest to me include: physiology, mechanical energetics, fluid dynamics, neural control, the evolution and design of underlying mechanisms, and metabolic energetics. So far, I have looked at gait changes in crayfish during submerged pedal locomotion, and the aerodynamic lift producing mechanism called delayed stall in relation to flapping bird wings. Currently, I am investigating both maneuvering flight in pigeons during flapping flight and responses to perturbations in quadrupedal (goats and dogs) locomotion.

Undergraduates

There are no undergraduate researchers at this time.

Maria de Boef

Research Interests: Broadly, my research interests are bone microstructure patterns and their formation. I study a variety of mammal and bird species to understand how function, physiological stresses and evolutionary history influence patterns in bone microstructure. It is my hope that these studies will give valuable information that can be applied to palaeontology and ecology.

At the Concord Field Station I am conducting a study using guinea fowl to compare patterns of bone formation under regular flight and running stress. I will be taking in vivo bone strain measurements in order to assess the relationship between bone strain and bone microstructure pattern formation.

Recent publications:
de Boef, M. and Larsson, H. C. E. (2007) Bone microstructure: quantifying bone vascular orientation. Can. J. Zool. 85(1): 63-70.