This book has been the go-to guide on sheep health, disease and production for veterinarians, farmers, farm advisors and veterinary, agricultural and applied science students since it was first published in 1993. Its authors are recognised internationally in the field of sheep health and production and have a lifetime of experience in the New Zealand sheep industry as well as wide exposure to sheep farmers working with practical production and flock health issues. This fourth edition is extensively revised and fully redesigned.

Photorefractive polymer composites are an unusually sensitive class of photopolymers. Physics of Photorefraction in Polymers describes our current understanding of the physical processes that produce a photorefractive effect in key composite materials. Topics as diverse as charge generation, dispersive charge transport, charge compensation and trapping, molecular diffusion, organic composite structure, and nonlinear optical wave coupling are all developed from a physical perspective. Emphasis is placed on explaining how these physical processes lead to observable properties of the polymers, and the authors discuss various applications, including holographic archiving.