effects of temperature and percentage of organic modifier were studied on retention and selectivity in rp-hplc using solvation parameter model. the system constants were determined by multiple linear regression analysis from experimental values in the retention factor for a group of different solutes with known descriptors by computer using the program spss/pc. the experimental results showed t...

In distributed database query optimization, one of the main factors affecting the performance of an execution strategy is the intermediate fragment sizes produced during the execution of the sub query operations. This paper analyses static vs. dynamic calculation for selectivity of intermediate relations generated in query processing. A Dynamic model for selectivity evaluation (DSET) has been p...

A detailed model of diffraction of Gaussian beams on plane uniform volume Bragg gratings based on a Kogelnik’s theory of coupled waves is presented. The model describes transmitting and reflecting gratings and takes into account spectral width and angular divergence of diffracted beams. Exact formulas for angular and spectral selectivity are derived. Conditions for Bragg diffraction based on co...

Direction selectivity in the retina requires the asymmetric wiring of inhibitory inputs onto four subtypes of On-Off direction-selective ganglion cells (DSGCs), each preferring motion in one of four cardinal directions. The primary model for the development of direction selectivity is that patterned activity plays an instructive role. Here, we use a unique, large-scale multielectrode array to d...

Vanderploeg, H.A. and Scavia, D., 1979. Calculation and use of selectivity coefficients of feeding: zooplankton grazing. Ecol. Modelling, 7: 135--149. A straightforward method of calculating selectivity coefficients (Wii) of predation from raw data, mortality rates of prey, filtering rates, feeding rates and electivity indices is derived. Results from a comparison of selectivity coefficients fo...

The study of selection and gating in potassium channels is a very important issue in modern biology. Indeed, such structures are known in essentially all types of cells in all organisms where they play many important functional roles. The mechanism of gating and selection of ionic species is not clearly understood. In this paper we study a model in which gating is obtained via an affinity-switc...