Kinematics of Invisible Hinge

Catching the invisible - aerodynamic tracks and kinematics of bat and bird flight

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Singularities of Hinge Structures

Motivated by the hinge structure present in protein chains and other molecular conformations, we study the singularities of certain maps associated to body-andhinge and panel-and-hinge chains. These are sequentially articulated systems where two consecutive rigid pieces are connected by a hinge, i.e. a codimension two axis. The singularities correspond to a dimensional drop in the linear span o...

Extremal Configurations of Hinge Structures

We study body-and-hinge and panel-and-hinge chains in R, with two marked points: one on the first body, the other on the last. For a general chain, the squared distance between the marked points gives a Morse-Bott function on a torus configuration space. Maximal configurations, when the distance between the two marked points reaches a global maximum, have particularly simple geometrical charact...

The Walldius hinge arthroplasty.

Eighty-three Walldius arthroplasties, performed by one surgeon as salvage operation on the knee joint between 1966 and 1972, were independently reviewed. The fifty-seven living patients with sixty-seven arthroplasties were interviewed and examined and the clinical records of the deceased patients were inspected. Sixty-seven arthroplasties (81 per cent) were successful and sixteen failed (19 per...

Fixed hinge knee arthroplasty.