In DSM, nicotine dependence is included under the general definition of substance dependence.  The essential feature of Substance Dependence is a cluster of cognitive, behavioral, and physiologic symptoms indicating that the individual continues use of the substance despite significant substance-related problems.
The Best Materials to Cover your Greenhouse. 1  Glass: The traditional greenhouse covering, glass is the preferred material for permanence. 2  Film Plastic: Film plastic is one sixth to one tenth of the cost per square foot of a glass covered structure.
Polycarbonate plastic film comes in a rigid format that makes it easy install on the greenhouseâs frame. Some polycarbonate is corrugated, while other products have two smooth outer layers that encase an inner corrugated structure, much like that of a cardboard box. Polycarbonate material allows up to 91 percent of the light into the greenhouse.