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.
Greenhouse Covering. Whether you're replacing existing greenhouse coverings or building a greenhouse you're sure to find the best greenhouse covering at FarmTek. Greenhouse glazing is the material that covers the greenhouse frame and the most widely used materials are polycarbonate and poly film.
ventilated greenhouse will depend on wind velocity and direction, greenhouse orientation, width of the greenhouse, outside air temperature and any air block-age by surrounding trees, buildings or adjacent green-houses. Naturally ventilated greenhouses should have at least 3- to 4-foot wide openings along the length of the greenhouse to allow crosswise ventilation by the prevailing wind currents.