Spinal stabilization for patients with metastatic lesions of the spine using a titanium spacer

Anterior decompression in spinal metastases of the corporal type with impending (n=5) or present (n=36) neurological complications was performed in 41 patients. For reconstruction, a titanium cylinder was inserted after spondylectomy and augmented with an anterior plate. The titanium implant can easily be adjusted to the length needed without necessitating expensive additional equipment. Outside the patient the implant is filled with polymethylmetacrylate, facilitating plate transfixation for rotational locking. There was a 30-day mortality of 9.7%. Pain relief was apparent in 38 of 41 patients (92.7%), and motor improvement was manifest in 31 of 35 cases (88.6%). Six patients did not present with any neurological symptoms pre- or postoperatively. Neurological deterioration was registered in only 1 case (2.4%). Surgical efficacy was maintained until the death of the patients. Though tumor recurrence at a different spinal level led to consecutive surgery in 5 patients, no implant dislocation occurred during the observation period (maximum 44 months), characterizing the procedure as a mechanically reliable and safe technique

Operative Behnadlungsstrategien bei Femurmetastasen

Weder Deckblatt noch Ihaltsverzeischnis vorhanden

Casimir force between sharp-shaped conductors

Casimir forces between conductors at the sub-micron scale cannot be ignored in the design and operation of micro-electromechanical (MEM) devices. However, these forces depend non-trivially on geometry, and existing formulae and approximations cannot deal with realistic micro-machinery components with sharp edges and tips. Here, we employ a novel approach to electromagnetic scattering, appropriate to perfect conductors with sharp edges and tips, specifically to wedges and cones. The interaction of these objects with a metal plate (and among themselves) is then computed systematically by a multiple-scattering series. For the wedge, we obtain analytical expressions for the interaction with a plate, as functions of opening angle and tilt, which should provide a particularly useful tool for the design of MEMs. Our result for the Casimir interactions between conducting cones and plates applies directly to the force on the tip of a scanning tunneling probe; the unexpectedly large temperature dependence of the force in these configurations should attract immediate experimental interest

Tunability of Critical Casimir Interactions by Boundary Conditions

We experimentally demonstrate that critical Casimir forces in colloidal systems can be continuously tuned by the choice of boundary conditions. The interaction potential of a colloidal particle in a mixture of water and 2,6-lutidine has been measured above a substrate with a gradient in its preferential adsorption properties for the mixture's components. We find that the interaction potentials at constant temperature but different positions relative to the gradient continuously change from attraction to repulsion. This demonstrates that critical Casimir forces respond not only to minute temperature changes but also to small changes in the surface properties.Comment: 4 figures; http://www.iop.org/EJ/article/0295-5075/88/2/26001/epl_88_2_26001.htm

Phase separation transition in liquids and polymers induced by electric field gradients

Spatially uniform electric fields have been used to induce instabilities in liquids and polymers, and to orient and deform ordered phases of block-copolymers. Here we discuss the demixing phase transition occurring in liquid mixtures when they are subject to spatially nonuniform fields. Above the critical value of potential, a phase-separation transition occurs, and two coexisting phases appear separated by a sharp interface. Analytical and numerical composition profiles are given, and the interface location as a function of charge or voltage is found. The possible influence of demixing on the stability of suspensions and on inter-colloid interaction is discussed.Comment: 7 pages, 3 figures. Special issue of the J. Phys. Soc. Ja