Everything you need to know

How to draw an inverse of a.

1. Draw a unit circle.

2. Draw a straight line from the point (a, 0) to the North Pole (0, 1). This is line A.

3. Mark the point of intersection between the circle and line A.

4. Draw a straight line from the point of intersection to the South Pole (0, -1). This is line B.

5. Mark the point of intersection between line B and x-axis. This point is (1/a, 0).

The reason is homothetic triangles.

## Herding Cells - With Electricity!

Researchers at UC Berkeley have managed to use an electric field to herd a flock of epithelial cells — a trick called galvanotaxis. It’s a very blunt tool at the moment, but scientists hope it can be refined and used to help wounds heal.