24 research outputs found
Why Do High School Students Choose Chemistry?
In our previous paper, we sought answers to the question: Whv do college students choose chemistry as a major? To follow up on that study, we have attempted to identify the major factors that lead high school students to anticipate a major in chemistry or in a closely related field
The Preparation of Dithiophosphinates from Secondary Phosphines and Sulfur under Alkaline Conditions
Experience Based Use of Landmark and Vector Based Orientation During Homing by the Ant Formica cunicularia (Hymenoptera: Formicidae)
Regioselective Synthesis of N-b-Hydroxyethylaziridines by the Ring-Opening Reaction of Epoxides with Aziridine Generated in Situ
Structural organization of the tetranuclear zinc di-iso-propyl phosphorodithioate complex [Zn4O{S2P(O-iso-C3H7))2}6] as probed by single-crystal x-ray diffraction and 13C and 31P CP/MAS NMR
Modelling place memory in crickets
Insects can remember and return to a place of interest using the surrounding visual cues. In previous experiments, we showed that crickets could home to an invisible cool spot in a hot environment. They did so most effectively with a natural scene surround, though they were also able to home with distinct landmarks or blank walls. Homing was not successful, however, when visual cues were removed through a dark control. Here, we compare six different models of visual homing using the same visual environments. Only models deemed biologically plausible for use by insects were implemented. The average landmark vector model and first order differential optic flow are unable to home better than chance in at least one of the visual environments. Second order differential optic flow and GradDescent on image differences can home better than chance in all visual environments, and best in the natural scene environment, but do not quantitatively match the distributions of the cricket data. Two models—centre of mass average landmark vector and RunDown on image differences—could produce the same pattern of results as observed for crickets. Both the models performed best using simple binary images and were robust to changes in resolution and image smoothin