The Dark Energy Survey took an entire decade to produce a value for the cosmological constant—and it’s smaller than you might think! There were other stories as well, including one about primeval black holes, and because I am inescapably drawn by the relentless gravity of black hole news, it’s included below, along with two other stories related in one way or another to heads.
If you smell natural gas in your house, you go looking for the source with your cute little retinas and their super-dense constellation of photoreceptive cells to determine that one of the gas knobs on the stove is open. Researchers at Johns Hopkins University grew retinal organoids in a lab to determine how human visual perception develops.
They discovered that retinoic acid determines whether a cone cell will specialize in sensing red or green light; the only species on the planet with red-light visual perception are humans and related primates.
The researchers found that high levels of retinoic acid at an early developmental stage correlated with higher ratios of green cones, which results in red-green colorblindness. Ultimately, the researchers hope to apply findings derived from retinal organoids to treatments for macular degeneration, in which photoreceptive cells in the center of the retina are lost.
At some point in history, as vertebrates evolved, heads started popping out—theorists believe that either segmental elements of the trunk evolved into a skull or that the head evolved as a separate, unsegmented body part.
2024-01-14 14:00:05
Article from phys.org