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Ventricular fibrillation is the leading cause of sudden cardiac death. In fibrillation, fragmented electrical waves meander erratically through the heart muscle, creating disordered and ineffective contraction. Theoretical and computer studies, as well as recent experimental evidence, have suggested that fibrillation is created and sustained by the property(More)
Hearing loss is most often the result of hair-cell degeneration due to genetic abnormalities or ototoxic and traumatic insults. In the postembryonic and adult mammalian auditory sensory epithelium, the organ of Corti, no hair-cell regeneration has ever been observed. However, nonmammalian hair-cell epithelia are capable of regenerating sensory hair cells as(More)
We have examined the level of on-going cell death in the chick vestibular epithelia using the TUNEL method and compared this to the rate of on-going cell proliferation. Utricles contained 22.6 +/- 6.8 TUNEL-labeled cells (mean +/- s.e.m.) while saccules contained 15.1 +/- 4.0, with approximately 90% being labeled hair cells. In separate experiments, chicks(More)
Scroll wave (vortex) breakup is hypothesized to underlie ventricular fibrillation, the leading cause of sudden cardiac death. We simulated scroll wave behaviors in a three-dimensional cardiac tissue model, using phase I of the Luo-Rudy (LR1) action potential model. The effects of action potential duration (APD) restitution, tissue thickness, filament twist,(More)
Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. To determine the mechanism by which wave breaks are generated during ventricular fibrillation, we conducted optical(More)
The spatial-temporal course of hair cell degeneration and hair cell death was examined in the mammalian cochlea following aminoglycoside treatment. Organotypic cultures were established from postnatal rats (P3) and treated with 1 mM neomycin sulfate for 12-48 h and analyzed using a live/dead assay under epifluorescence microscopy. Live hair cells were(More)
This paper considers premiums paid for initial intra-industry acquisitions part of a " buy-and-build " acquisition strategy for industry consolidation. We find that buy-and-build acquirers on average pay between 8 and 20% higher premiums for their first acquisition compared to acquirers that don't follow such a strategy. The higher premium can be explained(More)
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