Previous X-ray studies of have focused on the closed state of the potassium channel. Now the structure of a calcium-activated bacterial potassium channel has revealed the nature of the channel's open state. This provides a first view at high resolution of ion channel gating.

The Cartier-Perrin theorem, which was published in 1995 and is expressed in the language of nonstandard analysis, permits, for the first time perhaps, a clear-cut mathematical definition of the volatility of a financial asset. It yields as a byproduct a new understanding of the means of returns, of the beta coefficient, and of the Sharpe and Treynor ratios. New estimation techniques from automa...

In this work a hybrid training scheme for the supervised learning of feedforward neural networks is presented. In the proposed method, the weights of the last layer are obtained employing linear least squares while the weights of the previous layers are updated using a standard learning method. The goal of this hybrid method is to assist the existing learning algorithms in accelerating their co...

Newly hatched sea turtles exposed to artificially generated magnetic fields with parameters characteristic of two sites 3700 km apart, differing only in longitude, can distinguish the two apparent locations and orient appropriately.