Recent comments in /f/askscience

common_sensei t1_j71ja1p wrote

Reply to Back in the late 90s, I remember hearing that scientists “cloned a sheep”. What actually happened with the cloning, and what advancements have been made as a result of that? by foxmag86

A human version of sort of the same technique is used to make three-parent babies: https://www.nature.com/articles/nature.2017.21761

This avoids mitochondrial diseases by transferring a nucleus from a fertilized egg to a donor fertilized egg that had the nucleus removed. The baby ends up with the nuclear DNA of its biological parents but the mitochondrial DNA from the donor, hence three parents.

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radioactive_dude t1_j71hut0 wrote

Reply to comment by Gwaiian in A medical isotope made from nuclear weapons waste (Tc-99m) has a six-hour half-life. How do hospitals keep it in stock? by Gwaiian

You're welcome. The Mo-99 at Darlington is specifically in Unit 2, which was just completely refurbished and can operate now for another 30 years. There is also lots of exciting work happening in Chalk River, just not with a research reactor. If medical isotopes interest you, check out the work with Ac-225 in Chalk River as a targeted alpha therapy for cancer treatment.

https://www.cnl.ca/health-science-2/actinium-225/

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radioactive_dude t1_j71haxx wrote

Reply to comment by autoantinatalist in A medical isotope made from nuclear weapons waste (Tc-99m) has a six-hour half-life. How do hospitals keep it in stock? by Gwaiian

You can calculate decay by Nt=No(1/2)^(t/t1/2), where Nt is the number of atoms at time t, No is the original number of atoms, and t1/2 is the half-life. So 1 h later for a 6 h half-life means 89% of the dose is still there.

You would need to ask one of the pharmacists what they do if someone is late. I'm assuming there is a cutoff time.

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rootofallworlds t1_j71gl75 wrote

Reply to comment by pblack476 in Suppose I have a container of water with a ball floating on top of it. I put it outside overnight and the water freezes. Since the water's volume increases as it freezes, the ball is raised. Where does the increased gravitational potential energy come from? by schematicboy

Ice has less thermal energy than water at the same temperature, which more than offsets the slight increase in gravitational potential energy due to ice Ih (the stable form at STP) being less dense.

On a molecular level, when the water molecules have slowed enough with cooling they can form permanent (ish) hydrogen bonds with each other and the shape of the molecules creates the ice crystal structure, even though this means pushing the molecules apart a bit more.

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djublonskopf t1_j71ffx9 wrote

Reply to How did the Achilles tendon become known as such and what was it called before? by MarqoTheDragon

In 1693, the Dutch anatomist Philip Verheyden performed a dissection of his own leg (after it was amputated). Upon reaching the tendon we now call the Achilles Tendon, he jokingly (or poetically) referred to it as chorda Achillis, or "Achilles' sinew". This was the first recorded connection between a real part of human anatomy and the myth of Achilles, and several sources credit Verheyden with coining the association. (EDIT: This account appears to be apocryphal; apparently in his writings he credits several colleagues with coming up with the name.)

As for specifically calling it the Achilles tendon, that name was coined (in Latin, as tendo Achillis) in the early eighteenth century by German anatomy professor Lorenz Heister.

As to other mythological body parts:

  • The atlas vertebrae holds up the skull, just as the titan Atlas held up the sky in Greek mythology
  • The Latin lympha is derived from the Greek nymphe; lympha meaning "clean and pure water" after the Greek story of the nymphs. Our bodies' own lymph is so named.
  • See this paper investigating (with good citations) a whole bunch more.
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superkoning t1_j718yqc wrote

Reply to How did the Achilles tendon become known as such and what was it called before? by MarqoTheDragon

A bit related: https://physicaltherapyweb.com/human-anatomical-terms-with-interesting-origins/

among which

Adam’s Apple – The cartilaginous laryngeal prominence in males is believed to be so named because, in ancient times, it was supposedly thought to be a piece of forbidden fruit caught in Adam’s throat. There are conflicting arguments however, with the main counter-argument being that it is simply a mistranslation from another language.

... which is mythological for some people

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Medphysto t1_j7180gj wrote

Reply to comment by radioactive_giraffe in A medical isotope made from nuclear weapons waste (Tc-99m) has a six-hour half-life. How do hospitals keep it in stock? by Gwaiian

Nuclear physicist here. This guy has the right answer. I can add that these generators are compact in size (though heavy because of radiation shielding) and can be delivered to the hospital with fresh Mo-99 inside. The old generators with depleted Mo-99 are picked up when the new generators are delivered. The extraction of the Tc-99m can be done within the hospital. It actually gets sucked out of the generator with special syringes that have been manufactured with a defined underpressure inside and the first thing to do with a new generator after this sucking process (called elution) is to check it for Mo-99 contamination. Only <1% of Mo-99 is allowed (where I live, ymmv).

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