Radiology of congenital deformities of the ear

By depicting the status of the middle ear beyond atretic canals, multidirectional tomography can materially assist in the planning of surgery for conductive hearing losses. The course of the facial nerve is best demonstrated by the Guillen projection and by lateral projections. Deformities of the inner ear structures may be surveyed by similar projections. Deformities of the inner ear structures may be surveyed by similar projections. The base view accurately predicts the status of the cochlea. If lesions are classified as external canal deformities, middle ear deformities, or inner ear deformities, the clinician may more easily identify hereditary versus environmental syndromes.     

Uncovering microstructure and composition susceptibility of high permittivity ceramic granules to plasma-induced arc breakdown

Effective diversion of surge currents is vital to prevent unwanted damage to sensitive electronics. Among the most successful and efficient strategies relies on a dielectric stimulated arc breakdown mechanism with high permittivity ceramic granules in a spark-gap geometry. Although generally regarded as a self-healing process, substantial energy deposition may occur that, over time, diminishes the ability to withstand repeated electrical assaults. We investigate the susceptibility of lead–magnesium–niobate–lead titanate (PMN–PT) granule microstructure and composition changes following many exposures to high voltage impulses resulting in arc breakdown. Scanning electron microscopy and energy-dispersive spectroscopy mapping reveal a broad range of thermal and mechanical defects entailing thermal reduction of constituent PMN–PT metal ions and recasting due to rapid eruption of volatile species. Additionally, evidence of local melting and microcracking are apparent that can have deleterious impact on the proper function of the granules, namely, the ability to concentrate electric fields across air gaps to establish and sustain discharge pathways. We propose that the localized nature of damage and stochasticity associated with the dielectric stimulated breakdown mechanism may allow granules to maintain functionality provided no permanent conduction paths are established.