RESUMO
Hand transplantation is a form of composite tissue allotransplantation, whereby the hand of a cadaveric donor is transferred to the forearm of an amputee. The aim of such a procedure is to achieve better outcomes in terms of functionality and appearance when compared with prosthetics. The microsurgical techniques required have been well established for many years. In addition, advances in immunosuppressive therapy have meant that hand transplantation is a feasible therapeutic option. However this is not a life-saving procedure, requiring lifelong antirejection treatment with potentially serious side-effects. Hand transplantation is therefore a controversial concept with ethical, financial and psychological implications that need careful consideration. Before this treatment can be fully accepted, further research is still required; this should be directed towards achieving immunological tolerance, while minimizing costs and potential side-effects of post-transplant therapy.
RESUMO
The implementation of the van der Pauw (VDP) technique for combined high temperature measurement of the electrical resistivity and Hall coefficient is described. The VDP method is convenient for use since it accepts sample geometries compatible with other measurements. The technique is simple to use and can be used with samples showing a broad range of shapes and physical properties, from near insulators to metals. Three instruments utilizing the VDP method for measurement of heavily doped semiconductors, such as thermoelectrics, are discussed.
