functional response of the female ladybeetle, hippodamia variegata (goeze) (col., coccinellidae) to varying densities (5, 10, 20, 40, 60 and 80) of third instar nymphs of aphis gossypii glover was assessed in a growth chamber (25˚c, 65± ­5% rh and a photoperiod of 16l: 8d h), on the black eyed bean, vigna unguiculata (l.), in an open patch design. the logistic regression showed a type ii functi...

The development of an optical pH sensor based on immobilization of quinizarin (1,4-dihydroxyanthraquinone) on a triacetylcellulose membrane was described. The resulting membrane exhibited fast color change from yellow to violet, while changing the pH in alkaline region. The immobilized quinizarin showed a broader dynamic range from (pH 9.4-11.4) with respect to free form (pH 8.8-10.4). The sens...

Literature concerning the effects of Ramadan fasting on sports performance presents conflicting results. In this context, some studies reported a significant impairment of sports performance during the month of Ramadan. However, other studies suggested that Ramadan fasting has no significant effect on physical performance.  The discrepancies between the studies could be explained by time-of-day...

The simulation of step, impulse and ramp responses of linear continuous-time timeinvariant single-input single-output systems with a pure time delay in the feedback loop is tackled. Contrary to systems without time delay where a conversion from Laplace transform to z transform with a zero-order hold allows for an exact response, delay in the feedback loop requires either an unbounded number of ...

nuclear power reactors are, in nature nonlinear and time varying. these characteristics must be considered, if large power variations occur in their working regime. in this paper a robust optimal gain scheduling controller for regulating the power of a nuclear reactor has been designed and simulated. the proposed controller is capable of regulating power levels in a wide power range (10% to 100...

Many real-world numerical models are notorious for the time-scale separation of different subsets of variables and the inclusion of random processes. The existing algorithms of linear response to external forcing are vulnerable to the time-scale separation due to increased response errors at fast scales. Here we develop the approximate linear response algorithm for slow variables in a two-scale...

nowadays, the world is faced with diverse challenging issues which lead to the development of communities to discuss about the matter and provide solutions for them. academic research centers are then established to puzzle out the raised questions with reliance on expert opinions and studies in response to the current prevailing needs. islamic republic of iran blessed with knowledgeable academi...