Recent comments in /f/askscience

mfb- t1_jby09vc wrote

Reply to comment by not_natty in Is Radioactivity Inversely Proportional to Half Life? by not_natty

Could be similar to pharmacokinetics but I'm not familiar with the use of saturation there. You get this effect whenever you have an (almost) constant production and a decay that's proportional to the concentration. If we look at something like a month then Y-90 production is almost constant because Sr-90 decays slowly over decades. Y-90 decays are proportional to the amount of Y-90, so you start with almost nothing and approach an equilibrium within a few times the half life (~1 week).

If you start with a pure Sr-90 sample then its overall activity will double in that time frame, yes.

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not_natty OP t1_jbxy8gs wrote

Reply to comment by mfb- in Is Radioactivity Inversely Proportional to Half Life? by not_natty

Is this Y-90 accumulation where you get one Y-90 decay per Sr-90 decay similar to saturation in pharmacokinetics where at 5 half-lives the levels are 'stable'?

Assuming Sr-90 and Y-90 are pure beta emitters, does this mean that if I start with pure Sr-90 at x Bqs, given some time I'll actually end up with more radioactivity in the system, as in the combined Bqs of Sr-90 and Y-90 will be greater than the initial radioactivity of pure Sr-90?

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Half4sleep t1_jbwzja5 wrote

Reply to comment by ahufflepuffhobbit in Can long term cannabis abuse cause permanent changes to brain structure? by AlexMiles101

Now, I don't know too much about this myself, but jumping to a collusion about the correlation is dangerous.

People who eat a lot of cheese are more prone to heart attacks, does that mean cheese causes it? No, overweight people just eat more of it, and because they're fat they have an increased risk of heart diseases.

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Major_t0Ad t1_jbwx7av wrote

Reply to comment by Dr_Vesuvius in I just learned that the known shortest DNA in an “organism” is about 1700 base pairs in a certain virus. Is there a minimum amount of “code” required for an organism (or virus) to function in any capacity? by mcbergstedt

Adding to this awesome answer: ecologically speaking, the investment for offspring is much less dependent on sheer DNA mass for complex organisms than it is for bacteria. Bacteria optimize things unheard of for complex organisms, they have crazy selection pressure.

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