David A Penning

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To survive, organisms must avoid predation and acquire nutrients and energy. Sensory systems must correctly differentiate between potential predators and prey, and elicit behaviours that adjust distances accordingly. For snakes, strikes can serve both purposes. Vipers are thought to have the fastest strikes among snakes. However, strike performance has been(More)
Snakes are important predators that have radiated throughout many ecosystems, and constriction was important in their radiation. Constrictors immobilize and kill prey by using body loops to exert pressure on their prey. Despite its importance, little is known about constriction performance or its full effects on prey. We studied the scaling of constriction(More)
Across the diversity of vertebrates, bite force has been studied and suggested to have important ecological and evolutionary consequences. However, there is a notable lineage of vertebrates that use this performance trait yet are missing from the bite-force literature: the snakes. Snakes often rely on biting during prey subjugation and handling. Many snakes(More)
Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction(More)
Laboring patients with congenitally corrected transposition of the great arteries present an interesting challenge to anesthesiologists because of the physiological changes that take place during pregnancy and the stress induced by labor. This paper describes the detailed management of a symptomatic parturient with congenitally corrected transposition of(More)
Across ecosystems and trophic levels, predators are usually larger than their prey, and when trophic morphology converges, predators typically avoid predation on intraguild competitors unless the prey is notably smaller in size. However, a currently unexplained exception occurs in kingsnakes in the genus Lampropeltis Kingsnakes are able to capture,(More)
Certain combinations of drugs might kill drug-resistant tumours, and a method based on the CRISPR–Cas9 geneediting system offers a way to find them. Tumours often become resistant to individual drugs, leading clinicians to use combinations of medicines in the hope of thwarting resistance. Michael Bassik and his colleagues at Stanford University in(More)
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