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...

background the current distribution of and access to health services along with the future health needs of the population have prompted wide application of geographic information systems (giss). during recent years, gis has been used in public health management for planning and organization of healthcare services. this study investigates geographical accessibility of residential areas in bandar...

in recent research on modelling road collisions very little attention has been paid  to rear-end chain reaction collisions, which is characterized by more than two vehicles involved in a collision at the same time. the core aim of the present research is to develop a methodology to estimate such potential collision probabilities based on a proactive perspective, where deceleration rate to avoid...

the performance of nanoscale field effect diodes as a function of the spacer length between two gates is investigated. our numerical results show that the ion/ioff ratio which is a significant parameter in digital application can be varied from 101 to 104 for s-fed as the spacer length between two gates increases whereas this ratio is approximately constant for m-fed. the high-frequency perform...

background: identification of the effective factors in reducing response time in prehospital emergency medical service (ems) can assist in improving its services. this study aimed at reviewing the effect of applying global positioning system (gps) on response time of tehran ems ambulances. materials and methods: of 132 tehran ems stations, 24 ones were randomly selected, and relevant data, incl...

this paper deals with a delayed ratio-dependent functional response predator-prey model with a threshold harvesting policy. we study the equilibria of the system before and after the threshold. we show that the threshold harvesting can improve the undesirable behavior such as nonexistence of interior equilibria. the global analysis of the model as well as boundedness and permanence properties a...

tannase has several important applications in food, feed, chemical and pharmaceutical industries. in the present study, production of tannase by mutant strain, penicillium sp. ez-zh390, was optimized in submerged fermentation utilizing two statistical approaches. at first step, a one factor at a time design was employed to screen the preferable nutriments (carbon and nitrogen sources of the med...