It would seem that mild deviations in the shape of the firing rate from Heaviside (to a steep sigmoidal form) are reflected more in temporal speed than in spatial shape changes.
As long as there does not exist very reliable biological information about the size of the steepness parameter β and the shape of the firing rate function (S_{beta}), it seems that we have to be content with simulating with various (beta< infty).
Here, we follow the latter approach, which yields a good separation of the clusters in many cases, owing to the pronounced U-shape of the firing rate dependence on the PC1 projection in Fig. 5c, where the firing rate drops down to zero when the projection is zero.
The model predicts not only the mean rate of fire spread, but also the convex shape of the head-fire front resulting from three-dimensional effects.
This is due to a V-shape distortion of the fire front, which leads to an increase of the burnt surface rate by the fire over time.
These features indicate that the Drosophila olfactory system is robust against changes in the shape of the intraglomerular firing transformation for odor discrimination provided that the transformation is concave.
When Mr. Berman speaks at various forensic science conferences, the attendees are only too happy to provide him with story suggestions, like identifying guns by the shape of the bullets they fire.
"We got it from the shape of the land that fire could course right up the hill and was going to be an issue for us, and a risk that we would have to deal with," said Lambert.
It had the solidity and weight, and roughly the shape, of a fire hydrant (as did the rest of him, for that matter).
