BACKGROUNDOver 60 Asian and European families with cortical myoclonic tremor and epilepsy have been reported under various names. Cerebellar changes may be part of the syndrome. In this study, we ...report the neuropathology findings in a new Dutch familial cortical myoclonic tremor with epilepsy case and review the literature on this syndrome. METHODSNeuropathological investigations were performed for a third case of the Dutch pedigree. In addition, we searched the literature for pedigrees meeting the criteria for benign familial myoclonic tremor and epilepsy. RESULTSOur third Dutch case showed cerebellar Purkinje cell changes and a normal cerebral cortex. The pedigrees described show phenotypical differences, cerebellar symptoms and cerebellar atrophy to a variable degree. Japanese pedigrees with linkage to chromosome 8q have been reported with milder disease features than members of Italian pedigrees with linkage to chromosome 2p. French pedigrees (5p) possibly show even more severe and progressive disease, including cognitive changes and cerebellar features. DISCUSSIONCurrently, familial cortical myoclonic tremor is not listed by the International League Against Epilepsy, although it can be differentiated from other epileptic syndromes. Genetic heterogeneity and phenotypical differences between pedigrees exist. Cerebellar changes seem to be part of the syndrome in at least a number of pedigrees.
Metrology experiments can be limited by the noise produced by the laser involved via small fluctuations in the laser's power or frequency. Typically, active power stabilization schemes consisting of ...an in-loop sensor and a feedback control loop are employed. Those schemes are fundamentally limited by shot noise coupling at the in-loop sensor. In this letter we propose to use the optical spring effect to passively stabilize the classical power fluctuations of a laser beam. In a proof of principle experiment, we show that the relative power noise of the laser is stabilized from approximately \(2 \times 10^{-5}\) Hz\(^{-1/2}\) to a minimum value of \(1.6 \times 10^{-7}\) Hz\(^{-1/2}\), corresponding to the power noise reduction by a factor of \(125\). The bandwidth at which stabilization occurs ranges from \(400\) Hz to \(100\) kHz. The work reported in this letter further paves the way for high power laser stability techniques which could be implemented in optomechanical experiments and in gravitational wave detectors.
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