Multiple Scattering of Fractionally-Charged Quasiparticles

We employ shot noise measurements to characterize the effective charge of quasiparticles, at filling factor nu=1/3 of the fractional quantum Hall regime, as they scatter from an array of identical weak backscatterers. Upon scattering, quasiparticles are known to bunch, e.g., only three e/3 charges, or 'electrons' are found to traverse a rather opaque potential barrier. We find here that the effective charge scattered by an array of scatterers is determined by the scattering strength of an individual scatterer and not by the combined scattering strength of the array, which can be very small. Moreover, we also rule out intra-edge equilibration of e/3 quasiparticles over length scale of hundreds microns.Comment: 4 pages, 4 figure

Spinal Meningiomas

Spinal meningiomas make up less than 25% of all spine tumors, and are far less frequent than intracranial tumors. In the few last decades, a better knowledge of these tumors has significantly improved the surgical management of spinal cord meningiomas by demonstrating the relationship between patient status, outcome and the tumor pathology, tumor location and ossification; improvements in neurophysiological monitoring and neuro-anesthesia and the development of innovative variations to the traditional approaches to spinal cord tumors. In this chapter, we summarize the typical features of spinal meningiomas listing by incidence, prevalence, clinical and radiological patterns and histopathological types. Moreover, we describe the various types of surgical approaches usually performed for spinal meningioma excision, including the posterior approach, posterolateral approach, and anterior approach. We also describe the new T-line concept, which could be useful for decision-making about the most feasible approach for each case. Finally, we describe possible complications of this surgery and how to avoid them