Does congenital deafness affect the structural and functional architecture of primary visual cortex?

Deafness results in greater reliance on the remaining senses. It is unknown whether the cortical architecture of the intact senses is optimized to compensate for lost input. Here we performed widefield population receptive field (pRF) mapping of primary visual cortex (V1) with functional magnetic resonance imaging (fMRI) in hearing and congenitally deaf participants, all of whom had learnt sign language after the age of 10 years. We found larger pRFs encoding the peripheral visual field of deaf compared to hearing participants. This was likely driven by larger facilitatory center zones of the pRF profile concentrated in the near and far periphery in the deaf group. pRF density was comparable between groups, indicating pRFs overlapped more in the deaf group. This could suggest that a coarse coding strategy underlies enhanced peripheral visual skills in deaf people. Cortical thickness was also decreased in V1 in the deaf group. These findings suggest deafness causes structural and functional plasticity at the earliest stages of visual cortex

Medium-voltage pulse width modulated current source rectifiers using different semiconductors: loss and size comparison

In this study, a comparison of losses and physical size is presented for three semiconductor devices suitable for medium-voltage high-power applications. The comparison is made for medium-voltage pulse width modulated (PWM) current source rectifiers (CSRs) using a selective harmonic elimination technique. The devices are high-voltage insulated gate bipolar transistors and two types of hard-driven thyristors, namely the symmetrical gate commutated thyristor and the asymmetrical gate commutated thyristor. The study is based on practical devices using data sheets from semiconductor device vendors, taking into account accurate discrimination between turn-off and recovery states. The constant-voltage switching energy data sheet curves for voltage source converters are adapted to suit varying voltage applications like the PWM-CSR, with emphasis on how voltage is shared between series devices during each commutation instant