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Programmable variable pressure valves were introduced in the 1980s, providing a non-invasive solution to post-operative alterations of the valve opening pressure to address problems of under or overdrainage. Since their increased use in the treatment of hydrocephalus, there have been case reports of unintentional alterations of the valve opening pressure following exposure to magnetic fields in everyday environments, from televisions to rollercoasters. Here we describe two cases of patients' programmable valves being altered following audiology assessments. We subsequently discuss some of the available research on the safety of these valves in various magnetic field strengths, alongside interim and updated recommendations made by the British Society of Audiologists with regards to testing of children with programmable shunts in place. [ABSTRACT FROM AUTHOR]

Presents a fully parallel architecture for the computation of a two-dimensional discrete cosine transform (DCT), based on row-column decomposition. Use of the same one-dimensional DCT unit for the row and column computations and (N[sup 2] + N) registers to perform the transposition; Regularity and modularity of the architecture; Reduction of the number of accumulators from N to one.