Christopher R. Mitchell

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Nuptial food gifts function to enhance male fertilization success, but their consumption is not always beneficial to females. In decorated crickets, the spermatophore transferred at mating includes a gelatinous mass, the spermatophylax, which is consumed by females after mating. However, females often discard spermatophylaxes shortly after mating, whereupon(More)
Female mate choice is one mechanism of sexual selection and, provided there is adequate genetic variation in the male traits that are the target of this selection, they will evolve via female choice. Cuticular hydrocarbons (CHCs) are important in Drosophila mate choice, but relatively little is known about the underlying genetic architecture of CHC profiles(More)
Adapted hybrid prismatic-tetrahedral grid about a hemisphere. (b) Surface Mach contours on the symmetry plane for supersonic laminar ow (M 1 = 1:4, Re = 1000) 128]. 37 Figure 8. Comparison of various discretization methods for the circular advection problem 13]. (a) Grid used for the two-dimensional advection equation. (b) Piecewise-constant nite-volume(More)
permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Males can gather information on the risk and intensity of sperm competition from their social environment. Recent studies have implicated chemosensory cues, for instance cuticular hydrocarbons (CHCs) in insects, as a key source of this(More)
Our expectations for the evolution of chemical signals in response to sexual selection are uncertain. How are chemical signals elaborated? Does sexual selection result in complexity of the composition or in altered quantities of expression? We addressed this in Drosophila pseudoobscura by examining male and female cuticular hydrocarbons (CHs) after 82(More)
Females of many species obtain benefits by mating polyandrously, and often prefer novel males over previous mates. However, how do females recognise previous mates, particularly in the face of cognitive constraints? Female crickets appear to have evolved a simple but effective solution: females imbue males with their own cuticular hydrocarbons (CHCs) at(More)
Natural orifice endoscopic surgery can enable incisionless approaches, but a major challenge is the lack of small and dexterous instrumentation. Surgical robots have the potential to meet this need yet often disrupt the clinical workflow. Hand-held robots that combine thin manipulators and endoscopes have the potential to address this by integrating(More)
Phenotypic traits that convey information about individual identity or quality are important in animal social interactions, and the degree to which such traits are influenced by environmental variation can have profound effects on the reliability of these cues. Using inbred genetic lines of the decorated cricket, Gryllodes sigillatus, we manipulated diet(More)
Cuticular hydrocarbons (CHCs) play an essential role in mate recognition in insects but the form and intensity of sexual selection on CHCs has only been evaluated in a handful of studies, and never in a natural population. We quantified sexual selection operating on CHCs in a wild population of sagebrush crickets, a species in which nuptial feeding by(More)
INTRODUCTION Transurethral laser surgery using a flexible multi-backbone robot was recently demonstrated by Simaan et al. for bladder resection [1]. For transurethral prostate resection, thinner flexible manipulators are desirable. We have developed a hand-held system that transurethrally deploys two concentric tube robots through an 8.3 mm diameter rigid(More)