At the cellular level our bodies depend on a delicate balance of ions that is constantly adjusted. Potassium ions, for example, are atoms with one missing electron which are constantly streaming into or out of our cells. These positively charged ions enter and exit the cell via huge protein machines called channels which are imbedded in the cell wall and, like a donut, have a hole in the middle through which the ions flow. What is astonishing is how well these channels work. Not only do they open and close as needed, but they have two seemingly impossible design features. On the one hand they are extremely selective, allowing only a particular type of ion to flow through it. But Read More ›

Paul Giem provides the following guest post today: The following three pictures were made to represent trays with 560 coins with either white (heads) or black (tails) showing.  At least one of them was created by shaking coins and then spreading them out on a table (actually multiple shakes of 20 or so coins) and copying the pattern of heads and tails produced.  Which one or ones are they, and why?  Were the ones, if any, that were not done by this process designed, and if so by whom, and using what method? 1. 2.   3.