Science
Related: About this forumUsing analog computation circuits, engineers design cells that can compute logarithms, divide ...
... take square roots.
The full paper is only available with a subscription or purchase. I'd love to know how a cell, or a network of cells, can compute a logarithm.
From phys.org:
To create an analog adding or multiplying circuit that can calculate the total quantity of two or more compounds in a cell, the researchers combined two circuits, each of which responds to a different input. In one circuit, a sugar called arabinose turns on a transcription factor that activates the gene that codes for green fluorescent protein (GFP). In the second, a signaling molecule known as AHL also turns on a gene that produces GFP. By measuring the total amount of GFP, the total amount of both inputs can be calculated.
To subtract or divide, the researchers swapped one of the activator transcription factors with a repressor, which turns off production of GFP when the input molecule is present. The team also built an analog square root circuit that requires just two parts, while a recently reported digital synthetic circuit for performing square roots had more than 100.
"Analog computation is very efficient," Sarpeshkar says. "To create digital circuits at a comparable level of precision would take many more genetic parts."
Another of the team's circuits can perform division by calculating the ratio of two different molecules. Cells often perform this kind of computation on their own, which is critical for monitoring the relative concentrations of molecules such as NAD and NADH, which are frequently converted from one to the other as they help other cellular reactions take place.
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Skittles
(153,138 posts)need to watch for that
yodermon
(6,143 posts)sorry, obligatory
goldent
(1,582 posts)some physical phenomena that is logarithmic - many of which occur in nature (for example, certain operating regions of a diode are exponential - the inverse of log).
For the Nature article, here is what they say...
Now I don't understand this description, but I suspect they are again taking advantage of some natural process that is logarithmic.
Jim__
(14,073 posts)circuits. But, reading the abstract, it looks like they plan on utilizing them in biotech applications - like implanting them in an organism to detect changes in the biochemical environment. That makes more sense than using them in, say, circuits doing mathematical calculations.
tridim
(45,358 posts)and making digital music sound more "human".