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In eusocial insects, polyandrous mating has the potential to reduce genetic relatedness of individuals within a colony, which may have a profound effect on the stability and social structure of the colony. Here we present evidence that multiple mating is common in both males and females of the desert leaf-cutter ant Acromyrmex versicolor. Females seem to(More)
To facilitate the study of mating biology in the desert leaf-cutter antAcromyrmex versicolor, methods were developed that allowed storage and easy quantification of sperm samples collected from both male and female reproductive tracts. Sperm samples stored frozen were sonicated, stained with a fluorescent DNA stain, and the fluorescence emitted by the(More)
Many psychologists who study cognition believe that perception achieves object-centered representations that make it possible to extract representations of how the object would appear from differing viewpoints. Others believe we can achieve representations of how an object would appear by a process of visualization or mental rotation. We report experiments(More)
Induced movement occurs not only when an object surrounding a stationary one moves below threshold but when it moves above threshold. The above-threshold effect is particularly puzzling and seemingly irrational because the relative displacement should be fully accounted for by perceiving the moving object in motion. The accepted theory has been that such(More)
When a figure moves behind a narrow aperture in an opaque surface, if it is perceived as a figure, its shape will often appear distorted. Under such anorthoscopic conditions, the speed or direction of the object's motion is ambiguous. However, when the observer simultaneously tracks a moving target, a figure is always perceived, and its precise shape is a(More)
We have devised a novel diffuse interface formulation to model the development of chemical and physical inhomogeneities, i.e. microstructure, during the process of casting drug-eluting coatings. These inhomogeneities, which depend on the coating constituents and manufacturing conditions, can have a profound affect on the rate and extent of drug release, and(More)
Bimolecular quenching between photosensitizers and exchange-coupled transition metal complexes has been studied in an effort to experimentally establish a link between Heisenberg spin exchange and chemical reactivity. The acceptors are members of the oxo/hydroxo-biscarboxylato class of dinuclear Fe(III) compounds, where protonation of the oxo bridge(More)
Superconformal electrodeposition of copper is explained by the recently developed curvature-enhanced-accelerator coverage (CEAC) model, which is based on the assumptions that 1) the local growth velocity is proportional to the surface coverage of the accelerator, or catalyst, and 2) the catalyst remains segregated at the metal/electrolyte interface during(More)
Experiments are described which support the theory that the perception of a plane receding in depth is based on a process of construction. Displays were created which eliminated direct or higher-order stimulus information concerning the orientation of a plane, such as texture gradients or perspective. Instead, objects and the shadows they cast sufficed to(More)