The support of subsea oil and gas production operations involves the use of many underwater work systems. Divers can be used for support tasks in water depths to 300 m, but at more extreme depths operations become restrictively expensive and the efficiency of task performance is reduced. Remote controlled unmanned vehicles can replace the diver to a limited extent, performing inspection and maintenance tasks and supporting drilling opera tions. Operations in deepwaters performed by remote controlled vehicles and one man submersible vehicles, such as JIM and WASP, are more cost effective than...

Grass is a very important world crop. In some countries, for example the UK, Australia and New Zealand, animal products from grassland make a greater contribution to the value of agricultural production than does any other crop. Yet research being undertaken to further- our understanding of the factors affecting the growth and productivity of grasslands has trailed in the shadow of the determined efforts made to improve our knowledge of cereals and, to a somewhat lesser extent, legumes. However, in spite of its low profile, grassland research has resulted in considerable advances in our...