Two models for speciation via selection have been proposed. In the well-known model of 'ecological speciation', divergent natural selection between environments drives the evolution of reproductive isolation. In a second 'mutation-order' model, different, incompatible mutations (alleles) fix in different populations adapting to the same selective pressure. How to demonstrate mutation-order spec...

in the present research work, the kinetics of sunflower oil transesterification reaction in the presence of ba-sr/zsm-5 nanocatalyst which prepared using incipient wetness impregnation method was investigated. the 10wt.%ba-sr/zsm-5 (sr/ba=3/2) nanocatalyst was calcined at 600 °c for 6 h with a heating rate of 3 ºc/min. the experimental conditions were the methanol/oil 9/1molar ratio, reaction t...

we investigate a class of fourth-order differential operators with eigenparameter dependent boundary conditions and transmission conditions. a self-adjoint linear operator a is defined in a suitable hilbert space h such that the eigenvalues of such a problem coincide with those of a . we discuss asymptotic behavior of its eigenvalues and completeness of its eigenfunctions. finally, we obtain th...

For a lower semicontinuous function f on a Banach space X, we study the existence of a positive scalar μ such that the distance function dS associated with the solution set S of f(x) ≤ 0 satisfies dS(x) ≤ μmax{f(x), 0} for each point x in a neighborhood of some point x0 in X with f(x) < for some 0 < ≤ +∞. We give several sufficient conditions for this in terms of an abstract subdifferential and...