* Assiut University Bulletin For Environmental Researches Vol. 10 No. 1, March 2007 Contents Page Bulletin Cover Editorial Board Notice To Contributors . THE EFFECT OF WIND-CATCHERS EL-MALAQEF- ON THE INTERNAL NATURAL VENTILATION IN HOT CLIMATES WITH SPECIAL REFERENCE TO EGYPT: A STUDY ON SMALL PHYSICAL MODELS. Ahmed Abdel_Wahab Ahmed Rizk and Mohamed Abd Elmawgoud Abd Elghaffar … 1 · INTRA-ROW INTERCROPPING OF COWPEA AND CUCUMBER WITH OKRA AS INFLUENCED BY PLANTING DATE OF SECONDARY CROPS Magdy A. A. Mousa, Mohamed, F. Mohamed, Mohamed H. Dokashi and Emad-Elden F. E. Elnobi ..................................................... 13 · NUMERICAL SIMULATION AND EXPERIMENTAL STUDY ON STACK-GAS DISPERSION EMITTED FROM DIFFERENT ELEVATED POINT SOURCE IN AN URBAN ENVIRONMENT. Mohamed F. Yassin …………........................................... 35 · A PRACTICAL GUIDE FOR SCHOOL BUILDINGS MAINTENANCE. Mohamed Abd Elmawgoud Abd Elghaffar .................................................. 59 · LIFE-CYCLE ASSESSMENT TOOLS FOR MAINTENANCE MANAGEMENT AND RESOURCE CONSERVATION. Mohamed Abd Elmawgoud Abd Elghaffar ................................................ 73 · THE BIOLOGY OF EGYPTIAN WOODY PERENNIALS: 3. PLUCHEA DIOSCORIDIS (L.) DC. K. H. Shaltout and D. F. Slima ............................................................................. 85