Quirky Science
DISTANT GALAXY LENSED BY GRAVITY
A multinational team of astronomers has found an Einstein Ring, a rare image of a distant galaxy lensed by gravity. The scientists, from Spain, Italy and the USA, report their discovery in Monthly Notices of the Royal Astronomical Society.
In his seminal general theory of relativity published a century ago, Albert Einstein predicted that gravity would distort the fabric of spacetime, and that light would follow curved paths as a result. Astronomers first observed this effect in 1919, by measuring the position of stars near the Sun during the 1919 total solar eclipse, and noting a slight shift resulting from the gravitational field of our nearest star. On a larger scale, light from distant galaxies is bent by black holes and massive galaxies that lie between them and Earth. The intervening objects act as lenses, creating arcs and 'Einstein rings' of light.
These rings are still comparatively rare and usually appear as small features in the sky. This makes them hard to see clearly, and most are observed with radio telescopes, or with the Hubble Space Telescope. Their rarity derives from the huge distances involved, and the low probability of our Galaxy, the lens galaxy and the distant galaxy all being almost exactly in line.
PERFORMING COMPLEX COMPUTATIONS
Living cells are capable of performing complex computations on the environmental signals they encounter. These computations can be continuous, or analogue, in nature -- the way eyes adjust to gradual changes in the light levels. They can also be digital, involving simple on or off processes, such as a cell's initiation of its own death.
Synthetic biological systems, in contrast, have tended to focus on either analogue or digital processing, limiting the range of applications for which they can be used.
But now a team of researchers at MIT has developed a technique to integrate both analogue and digital computation in living cells, allowing them to form gene circuits capable of carrying out complex processing operations.
The synthetic circuits, presented in a paper published in the journal Nature Communications, are capable of measuring the level of an analogue input, such as a particular chemical relevant to a disease, and deciding whether the level is in the right range to turn on an output, such as a drug that treats the disease.
In this way they act like electronic devices known as comparators, which take analogue input signals and convert them into a digital output, according to Timothy Lu, an associate professor of electrical engineering and computer science and of biological engineering, and head of the Synthetic Biology Group at MIT's Research Laboratory of Electronics, who led the research alongside former microbiology PhD student Jacob Rubens.
Source: Sciencedaily.com
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