Corrections

December 2006, page 8 —The distance in parentheses in the last line of the third column should read 89 000 light years.

December 2006, page 9 —The equation in the second column should read MG = V²r.

December 2006, page 46 —The scale bar label in figure c of box 2 should read 1 mm.

December 2006, page 60 —In the review of Introduction to Microfluidics , the sixth sentence in the sixth paragraph should begin, “Although droplet motion by surface-energy gradients is also considered….” The first sentence in the eighth paragraph should begin, “The same qualities then that make the book an entertaining and painless entrée into the field of microfluidics, however, may leave physics students dissatisfied….”