in many real systems in which a state variable should be controlled for being in appropriate range, the length of control (review) intervals is taken to be constant. in such systems, when the cost of reviews and out-of-range values of the state variable are considerable, this method may not be optimal. in this paper we let the length of review intervals to be variable during each operating cycl...

A program schema defines a class of programs, all of which have identical statement structure, but whose functions and predicates may differ. A schema thus defines an entire class of programs according to how its symbols are interpreted. Two schemas are strongly equivalent if they always define the same function from initial states to final states for every interpretation. A subschema of a sche...

Urinary acidification in the turtle urinary bladder is due to a reversible proton-translocating ATPase. To estimate the H+/ATP stoichiometry of this pump, we measured the delta G'ATP in the epithelial cells and the maximum e.m.f. generated by the pump. The latter is the maximal transepithelial electrochemical gradient for protons placed across the epithelium that is needed to nullify the rate o...

a sensitive fluorometric method for the determination of deferiprone (dfp) based on the formation of a luminescent complex with tb3+ ions in aqueous solutions is reported. the maximum excitation and emission wavelengths were 295 and 545 nm, respectively. the effects of various factors on the luminescence intensity of the system were investigated and optimized, then under the optimum conditions,...