In this issue of Neuron, Li et al. (2013) show that transgenically eliminating thalamocortical neurotransmission disrupts the formation of barrel columns in the somatosensory cortex and cortical lamination, providing evidence for the importance of extrinsic activity-dependent factors in cortical development.

Using the lamination theory developed by Colding and Minicozzi for sequences of embedded, finite genus minimal surfaces with boundaries going to infinity [5], we show that the space of genus-one helicoids is compact (modulo rigid motions and homotheties). This generalizes a result of Hoffman and White [12].

The South Saskatchewan River has a long term average discharge of 275 m3/sec, with flood peaks in the range of IS00 to 3800 nP/sec. South of Saskatoon, the four major types of geomorphological elements recognised are channels, slipfacebounded bars, sand flats and vegefated islands and floodplains. Major channels are 3-5 m deep, up to 200 m wide, and flow around sand flats which are 50-2000 m lo...