Publications by authors named "Stephen E Johnson"

While we know that climate change can potentially cause rapid phenotypic evolution, our understanding of the genetic basis and degree of genetic parallelism of rapid evolutionary responses to climate change is limited. In this study, we combined the resurrection approach with an evolve-and-resequence design to examine genome-wide evolutionary changes following drought. We exposed genetically similar replicate populations of the annual plant Brassica rapa derived from a field population in southern California to four generations of experimental drought or watered conditions in a greenhouse.

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Premise: Changes in climate can impose selection on populations and may lead to rapid evolution. One such climatic stress is drought, which plant populations may respond to with escape (rapid growth and early flowering) or avoidance (slow growth and efficient water-use). However, it is unclear if drought escape would be a viable strategy for populations that already flower early from prior selection.

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Climate change is driving evolutionary and plastic responses in populations, but predicting these responses remains challenging. Studies that combine experimental evolution with ancestor-descendant comparisons allow assessment of the causes, parallelism, and adaptive nature of evolutionary responses, although such studies remain rare, particularly in a climate change context. Here, we created experimental populations of Brassica rapa derived from the same natural population and exposed these replicated populations to experimental drought or watered conditions for four generations.

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Article Synopsis
  • The study examined the effects of playing the trumpet on the strength and endurance of facial muscles, specifically the lips, cheeks, and tongue, comparing adult trumpet players who practice regularly to non-players.
  • It involved 16 trumpet players and 16 healthy controls, measuring muscle strength and endurance using a specialized instrument known as the Iowa Oral Performance Instrument.
  • Results showed that trumpet players had significantly greater cheek strength and lip endurance compared to controls, while tongue strength and endurance were similar between the two groups, with some age-related declines noted.
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Problem: Safety professionals have increasingly turned their attention to social science for insight into the causation of industrial accidents. One social construct, safety climate, has been examined by several researchers [Cooper, M. D.

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Problem: Injuries resulting from lifting are costly, and create significant pain and discomfort. While engineering controls are the most effective means of reducing risks, most organizations continue to rely on manual lifting techniques. The problem, however, is that the use of safe-lifting techniques is inconsistent and managers have a difficult time motivating use of these techniques.

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