lpetrich
Contributor
The Nobel Prize in Physics 2017
Their first successful observation was on 2015 September 14. Two black holes spiraled into each other some 1.4 billion light years away, black holes with masses 35 and 30 times that of the Sun. They radiated away about 3 solar masses of gravitational waves, leaving a rapidly-rotating 62-solar-mass black hole. In the last bit of their inspiral, their gravitational-wave luminosity was about as great as that of all the stars in the observable Universe.
Since then, LIGO has detected three more GW events, and one of them has also been observed by VIRGO, a similar interferometer near Pisa, Italy. LIGO and Virgo observatories detect gravitational wave signals from black hole collision,
List of gravitational wave observations.
The Nobel Prize in Chemistry 2017
The Nobel Prize in Physiology or Medicine 2017
Many organisms are known to have circadian clocks, and since the 1930's, evidence has accumulated that they are genetically controlled. More recently, several circadian-clock genes have been identified. Their mechanism of operation of some of them was elucidated by studying Drosophila fruit flies, everybody's favorite lab insect. They work by making a Transcription-Translation Feedback Loop. Here's a very simplified version of the fruit-fly TTFL:
Start with the gene "period" (PER). Express it, making messenger RNA. Make the PER protein from that mRNA. This PER protein then represses its gene, and its mRNA gets recycled. This causes the amount of PER to level off.
This is much like a lot of other gene regulation, but there's a twist. Another protein causes the PER protein to degrade, and as it does so, the resulting absence of this protein causes the PER gene to be expressed again.
The actual cycle is more complicated, of course, with several proteins for stabilizing it and for making its period 24 hours.
Elsewhere in the animal kingdom, mammalian circadian clocks work in the same way, and even have some genes that are homologous with the fruit-fly version. So this mechanism must have been present in some very early animal, some itty-bitty worm that lived on the ocean floor a little before the beginning of the Cambrian.
Plants have a similar mechanism, but its proteins are not homologous to the animal ones.
Cyanobacteria have a mechanism that works on different principles, adding phosphate groups to protein molecules without involving transcription or translation.
Some multicelled organisms, at least, have ways of keeping their cells' clocks in sync. Vertebrates have a master clock in the suprachiasmatic nucleus (SCN) in their pituitary, and it controls other clocks elsewhere in their bodies. Various internal organs and tissues can continue to have circadian rhythms when in isolation.
LIGO is the Laser Interferometer Gravitational-Wave Observatory. It is a pair of supersensitive interferometers, one in Livingston LA, and one in Hanford WA, both in the United States. They bounce laser light back and forth several times through two evacuated tubes with different directions, and then combine the light to find out how much one of them is stretched or squeezed relative to the other one. They are so sensitive that they can detect gravitational-wave distortions with a size of 10^(-21). That's the size of an atom relative to the distance between the Earth and the Sun.
Their first successful observation was on 2015 September 14. Two black holes spiraled into each other some 1.4 billion light years away, black holes with masses 35 and 30 times that of the Sun. They radiated away about 3 solar masses of gravitational waves, leaving a rapidly-rotating 62-solar-mass black hole. In the last bit of their inspiral, their gravitational-wave luminosity was about as great as that of all the stars in the observable Universe.
Since then, LIGO has detected three more GW events, and one of them has also been observed by VIRGO, a similar interferometer near Pisa, Italy. LIGO and Virgo observatories detect gravitational wave signals from black hole collision,
List of gravitational wave observations.The Nobel Prize in Chemistry 2017
Their method: freezing a sample very fast, and then using an electron microscope on it. That makes it possible to observe biological molecules in their original environments, like cell-membrane proteins in cell membranes.
The Nobel Prize in Physiology or Medicine 2017
That's our daily rhythm: how we know when to sleep and when to wake up. All controlled by an internal molecular-scale clock.
Many organisms are known to have circadian clocks, and since the 1930's, evidence has accumulated that they are genetically controlled. More recently, several circadian-clock genes have been identified. Their mechanism of operation of some of them was elucidated by studying Drosophila fruit flies, everybody's favorite lab insect. They work by making a Transcription-Translation Feedback Loop. Here's a very simplified version of the fruit-fly TTFL:
Start with the gene "period" (PER). Express it, making messenger RNA. Make the PER protein from that mRNA. This PER protein then represses its gene, and its mRNA gets recycled. This causes the amount of PER to level off.
This is much like a lot of other gene regulation, but there's a twist. Another protein causes the PER protein to degrade, and as it does so, the resulting absence of this protein causes the PER gene to be expressed again.
The actual cycle is more complicated, of course, with several proteins for stabilizing it and for making its period 24 hours.
Elsewhere in the animal kingdom, mammalian circadian clocks work in the same way, and even have some genes that are homologous with the fruit-fly version. So this mechanism must have been present in some very early animal, some itty-bitty worm that lived on the ocean floor a little before the beginning of the Cambrian.
Plants have a similar mechanism, but its proteins are not homologous to the animal ones.
Cyanobacteria have a mechanism that works on different principles, adding phosphate groups to protein molecules without involving transcription or translation.
Some multicelled organisms, at least, have ways of keeping their cells' clocks in sync. Vertebrates have a master clock in the suprachiasmatic nucleus (SCN) in their pituitary, and it controls other clocks elsewhere in their bodies. Various internal organs and tissues can continue to have circadian rhythms when in isolation.