taxus    is an endangered plant which is the only commercial source of paclitaxel, which is used for treatment of ovary and breast cancer. as production of this valuable drug is a destructive process, other alternatives should be considered for its sustainable production. plant tissue and cell culture is a promising method for production of secondary metabolites. in order to optimize yew callus...

Old-growth forests are those that meet some threshold(s) determined by a scientific and political process. The main issue is what criteria to use to determine these thresholds; they must be practical enough to allow managers to delimit and manage old-growth stands in the field. People value forests with old and (or) big trees and primary forests that have a continuous heritage of natural distur...

some criteria of density in beech saplings were studied in various forest associations (mainly galio odorati-fagetum typicum) growing in the submontane region near zurich (swiss central plateau). the sample plots were established in regeneration gaps resulting from swiss irregular shelter wood system (femelschlag). five sample plots, each 2x2m in 3 transects (a total of 15 plots in each gap, x ...

This paper is evolved to have insight of Plankton-Nutrients interactions in the presence of delay in the growth term of phytoplankton species .The conditions for asymptotic stability about endemic equilibrium are derived in the absence of delay.The Nyquist criteria is used to estimate the length of delay to preserve stability .Analytic criterion for the existence of hopf-bifurcation is also dis...

This study compared the use of five different models to describe the growth from birth to 20 weeks of age of kids from both genders of nondescript goats. Fifty nine (59) nondescript kids were weighed weekly at the university of Maiduguri livestock teaching and research farm, Nigeria and the live weights were modeled. Biologically relevant variables were estimated for each kid from the Logistic,...