Energy harvesting that are able to operate in higher temperature gradients, and that can conduct electricity well without also conducting heat (something that was until recently thought impossible ), will result in increased efficiency. Future work in thermoelectrics could be to convert wasted heat, such as in automobile engine combustion, into electricity. This type of harvesting is based on the changing capacitance of vibration-dependent capacitors. Vibrations separate the plates of a charged variable capacitor, and mechanical energy is converted into electrical energy. Electrostatic energy harvesters need a polarization source to work and to convert mechanical energy from vibrations into electricity. The polarization
Feathers: The Evolution of a Natural Miracle and how feather insulation has also been utilized by humans. "Flight" discusses how flight might have evolved in birds, interviewing Prum, Feduccia, Xu, and also ornithologist Ken Dial, who described wing-assisted incline running. In "Fancy", Hanson discusses the role of feathers in sexual selection, as well as how humans have utilized feathers for fashion, interviewing costume and fashion designers on the Las Vegas Strip and New York City. "Function" discusses how feathers have been adapted for other purposes, such as waterproofing, fly fishing, and quill pens. Hanson decided he would write "Feathers" after going on a run and noticing a