Standing and travelling waves in a spherical brain model: the Nunez model revisited

The Nunez model for the generation of electroencephalogram (EEG) signals is naturally described as a neural field model on a sphere with space-dependent delays. For simplicity, dynamical realisations of this model either as a damped wave equation or an integro- differential equation, have typically been studied in idealised one dimensional or planar settings. Here we revisit the original Nunez model to specifically address the role of spherical topology on spatio-temporal pattern generation. We do this using a mixture of Turing instability analysis, symmetric bifurcation theory, center manifold reduction and direct simulations with a bespoke numerical scheme. In particular we examine standing and travelling wave solutions using normal form computation of primary and secondary bifurcations from a steady state. Interestingly, we observe spatio-temporal patterns which have counterparts seen in the EEG patterns of both epileptic and schizophrenic brain conditions

Fractura triplana epifisaria distal de tibia: a propósito de un caso con interposición de periostio

Se presenta un caso de fractura triplana en 2 fragmentos en un paciente varón de 13 años tratado quirúrgicamente, observando la interposición perióstica en el plano axial a nivel del fragmento antero-externo, que impedía la reducción anatómica de la zona epifisaria articular. Se analiza la anatomía quirúrgica de las fracturas triplanas considerando que esta lesión puede ser más frecuente de lo que se ha informado, y sólo valorada en los casos en que se emplee un abordaje antero-externo.The case of a 13-year-old boy with a two-fragment triplane fracture of the distal epiphysis of the tibia is presented. At surgery, an interposition of the periosteum in the axial plane behind the antero-lateral fragment, preventing the anatomical reduction of the epiphyseal joint surface was found. The surgical anatomy of triplane fractures is review taking into account that this lesion can be more frequent that it has been reported. The true incidence should be evaluated at surgery by antero-lateral approach

Band-structure trend in hole-doped cuprates and correlation with Tcmax

By calculation and analysis of the bare conduction bands in a large number of hole-doped high-temperature superconductors, we have identified the energy of the so-called axial-orbital as the essential, material-dependent parameter. It is uniquely related to the range of the intra-layer hopping. It controls the Cu 4s-character, influences the perpendicular hopping, and correlates with the observed Tc at optimal doping. We explain its dependence on chemical composition and structure, and present a generic tight-binding model.Comment: 5 pages, Latex, 5 eps figure

Fracturas del macizo trocantéreo. Estudio comparativo Ender-DHS: revision de 114 casos

Se presenta un estudio retrospectivo de 114 fracturas pertrocantéreas tratadas con enclavado elástico de Ender (71) y tornillo placa deslizante, DHS (43). Se efectuó un estudio estadístico descriptivo-comparativo entre los 2 grupos de pacientes según la técnica quirúrgica empleada. Se constató un mayor índice de estabilidad usando el DHS (81%), frente al 6 1 % del otro grupo. La tasa de complicaciones fue del 16% y 55% respectivamente. Los resultados clínicos fueron mejores en los enfermos tratados con DHS, fundamentalmente en cuanto a la deambulación que se consiguió en el 98% (Ender 75%), ausencia de dolor y movilidad conservada. Los autores piensan que la estabilidad preoperatoria no influye en la solidez del montaje usando el DHS, pero con la técnica de Ender ésta disminuye en las fracturas inestables; por ello, la técnica de Ender estaría solamente indicada en el tratamiento de fracturas estables en pacientes de edad avanzada o con mal estado general, aunque en clara competencia con el DHS.A retrospective study of 114 intertrochanteric fractures operated on either with Ender's rods (71) or dynamic hip screws, DHS (43) is presented. A statistical descriptive-comparative study between the 2 groups was attempted. There was a greater index of stability using the DHS (82%) than Ender's rods (61%). The rate of complications was 16% and 55% respectively. The clinical outcome was better in cases treated with DHS, specially for walking ability, which was regained in the 98% of cases (Ender 75%), painless and preserved mobility. The authors think that the stability before operation do not influence the solidity of the assembly using the DHS device. On the contrary, with the Ender's technique the fixation is no satisfactory in unstables fractures. Ender's rods would only be suitable for treatment of stable fractures in older patient or with serious associated diseases, although in clear competition with the DHS