The capacity for aerial maneuvering was likely a major influence on the evolution of flying anima... more The capacity for aerial maneuvering was likely a major influence on the evolution of flying animals. Here we evaluate consequences of paravian morphology for aerial performance by quantifying static stability and control effectiveness of physical models for numerous taxa sampled from within the lineage leading to birds (Paraves). Results of aerodynamic testing are mapped phylogenetically to examine how maneuvering characteristics correspond to tail shortening, forewing elaboration, and other morphological features. In the evolution of Paraves we observe shifts from static stability to inherently unstable aerial planforms; control effectiveness also migrated from tails to the forewings. These shifts suggest that a some degree of aerodynamic control and capacity for maneuvering preceded the evolution of a strong power stroke. The timing of shifts also suggests features normally considered in light of development of a power stroke may play important roles in control. JR. 2013. Linking the evolution of body shape and locomotor biomechanics in bird-line archosaurs. Nature 497:104-107 DOI 10.1038/nature12059. Beebe CW. 1915. A tetrapteryx stage in the ancestry of birds. Zoologica 2:39-52. Benton MJ. 2005. Vertebrate paleontology. Malden, MA: Blackwell Publishing. Burch SH. 2014. Complete forelimb myology of the basal theropod dinosaur Tawa hallae based on a novel robust muscle reconstruction method. Mindell D. 2004. Phylogenetic relationships among modern birds (Neornithes): toward an avian tree of life. In: Cracraft J, Donoghue MJ, eds. Assembling the tree of life. Oxford: Oxford University Press, 468-489. Davis M. 2008. Four winged dinosaur. NOVA television broadcast on PBS, February 26, 2008. Dial K. 2003. Wing-assisted incline running and the evolution of flight. Science 299:402-404 Tse K, Koehl M. 2014b. Aerodynamic characteristics of a feathered dinosaur measured using physical models. effects of form on static stability and control effectiveness. PLoS ONE 9:e85203 JK. 2008. A new basal lineage of early Cretaceous birds from China and its implications on the evolution of the avian tail. Paleontology 51:775-791
Student-run clinics (SRCs) provide preclerkship medical students with systems-based practice (SBP... more Student-run clinics (SRCs) provide preclerkship medical students with systems-based practice (SBP) experiences as they engage in patient care and manage clinic operations. This study explored the types and context of SBP activities students participate in at SRCs. Between November 2011 and February 2012, the authors conducted in-depth, semistructured interviews with a purposive sample of medical students who served as volunteers and coordinators (student leadership role) at four independently run SRCs within the University of California, San Francisco, School of Medicine. They also interviewed SRC faculty advisors. Interviews focused on student roles in SRCs, SBP learning opportunities in SRCs, and comparisons of SBP experiences in SRCs with those in the formal preclerkship curriculum. The authors used thematic analysis techniques to code and synthesize data. Data from interviews with 8 volunteers, 14 coordinators, and 4 faculty suggested six major domains related to SBP learning opportunities in SRCs: interprofessional roles and collaboration; clinic organization; patient factors affecting access to care; awareness of the larger health care system and continuity of care; resource acquisition and allocation; and systems improvement. Coordinators, who managed SRCs, demonstrated greater depth of SBP understanding than volunteers, who provided patient care. Students and faculty agreed that SRCs provided students with SBP learning opportunities beyond those available in the formal curriculum. Preclerkship students' participation in SRCs provides opportunities for in-depth learning of SBP, particularly among students who take on leadership roles. SRCs may model ways to effectively introduce key components of SBP to early medical learners.
We report the effects of posture and morphology on the static aerodynamic stability and control e... more We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, { Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While { M. gui lived after { Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.
The capacity for aerial maneuvering was likely a major influence on the evolution of flying anima... more The capacity for aerial maneuvering was likely a major influence on the evolution of flying animals. Here we evaluate consequences of paravian morphology for aerial performance by quantifying static stability and control effectiveness of physical models for numerous taxa sampled from within the lineage leading to birds (Paraves). Results of aerodynamic testing are mapped phylogenetically to examine how maneuvering characteristics correspond to tail shortening, forewing elaboration, and other morphological features. In the evolution of Paraves we observe shifts from static stability to inherently unstable aerial planforms; control effectiveness also migrated from tails to the forewings. These shifts suggest that a some degree of aerodynamic control and capacity for maneuvering preceded the evolution of a strong power stroke. The timing of shifts also suggests features normally considered in light of development of a power stroke may play important roles in control. JR. 2013. Linking the evolution of body shape and locomotor biomechanics in bird-line archosaurs. Nature 497:104-107 DOI 10.1038/nature12059. Beebe CW. 1915. A tetrapteryx stage in the ancestry of birds. Zoologica 2:39-52. Benton MJ. 2005. Vertebrate paleontology. Malden, MA: Blackwell Publishing. Burch SH. 2014. Complete forelimb myology of the basal theropod dinosaur Tawa hallae based on a novel robust muscle reconstruction method. Mindell D. 2004. Phylogenetic relationships among modern birds (Neornithes): toward an avian tree of life. In: Cracraft J, Donoghue MJ, eds. Assembling the tree of life. Oxford: Oxford University Press, 468-489. Davis M. 2008. Four winged dinosaur. NOVA television broadcast on PBS, February 26, 2008. Dial K. 2003. Wing-assisted incline running and the evolution of flight. Science 299:402-404 Tse K, Koehl M. 2014b. Aerodynamic characteristics of a feathered dinosaur measured using physical models. effects of form on static stability and control effectiveness. PLoS ONE 9:e85203 JK. 2008. A new basal lineage of early Cretaceous birds from China and its implications on the evolution of the avian tail. Paleontology 51:775-791
Student-run clinics (SRCs) provide preclerkship medical students with systems-based practice (SBP... more Student-run clinics (SRCs) provide preclerkship medical students with systems-based practice (SBP) experiences as they engage in patient care and manage clinic operations. This study explored the types and context of SBP activities students participate in at SRCs. Between November 2011 and February 2012, the authors conducted in-depth, semistructured interviews with a purposive sample of medical students who served as volunteers and coordinators (student leadership role) at four independently run SRCs within the University of California, San Francisco, School of Medicine. They also interviewed SRC faculty advisors. Interviews focused on student roles in SRCs, SBP learning opportunities in SRCs, and comparisons of SBP experiences in SRCs with those in the formal preclerkship curriculum. The authors used thematic analysis techniques to code and synthesize data. Data from interviews with 8 volunteers, 14 coordinators, and 4 faculty suggested six major domains related to SBP learning opportunities in SRCs: interprofessional roles and collaboration; clinic organization; patient factors affecting access to care; awareness of the larger health care system and continuity of care; resource acquisition and allocation; and systems improvement. Coordinators, who managed SRCs, demonstrated greater depth of SBP understanding than volunteers, who provided patient care. Students and faculty agreed that SRCs provided students with SBP learning opportunities beyond those available in the formal curriculum. Preclerkship students' participation in SRCs provides opportunities for in-depth learning of SBP, particularly among students who take on leadership roles. SRCs may model ways to effectively introduce key components of SBP to early medical learners.
We report the effects of posture and morphology on the static aerodynamic stability and control e... more We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur, { Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. While { M. gui lived after { Archaeopteryx and likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies are tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver.
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