| thrombocytopenia-absent radius syndrome | <syndrome> Tar stands for thrombocytopenia (low blood platelets) and aplasia (absence) of the radius (the long bone on the thumb-side of the forearm), features characterizing this syndrome. There is phocomelia (flipper-limb) with the thumbs always present. The fibula (the smaller bone in the lower leg) is often absent. The risk of bleeding from too few platelets is high in early infancy but lessens with age. The condition is inherited in an autosomal recessive trait with one gene (on a non-sex chromosome) coming from each parent to the tar child. Alternative names include thrombocytopenia-absent radius syndrome, radial aplasia-thrombocytopenia syndrome, and tetraphocomelia-thrombocytopenia syndrome. (12 Dec 1998) |
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| effective collision radius | <radiobiology> Effective size of a particle equal to the square root of (cross-section/pi). Determines the effective range of interaction of the particle. (09 Oct 1997) |
| tuberosity of radius | An oval projection from the medial surface of the radius just distal to the neck, giving attachment on its posterior half to the tendon of the biceps. Synonym: tuberositas radii, bicipital tuberosity, tuber radii, tuberosity of radius. (05 Mar 2000) |
| finite larmor radius | (FLR) In many plasma theories the size of the Larmor radius (or gyroradius) is assumed to be negligibly small, or infinitesimal. Different effects occur when the size of the Larmor radius is finite and needs to be considered. (09 Oct 1997) |
| larmor radius | <radiobiology> The radius of the path of a charged particle moving in a magnetic field (and transverse to the field lines). Synonym: gyroradius, cyclotron radius. (09 Oct 1997) |