Recent comments in /f/askscience

Evianicecubes t1_j3iekjr wrote

Reply to comment by ihaveredhaironmyhead in How does the spindle apparatus know what to do during cell division? by ihaveredhaironmyhead

There are protein complexes which identify the centromeres of the chromosomes to be targeted by the spindle apparatus. The protein complexes bind specifically to the centromeres of the chromosomes. Is this sort of what you were looking for?

I think what foxes was saying is that these interactions are passive, not controlled by a nervous system or anything.

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SirWLawrence t1_j3huegj wrote

Reply to comment by daywalkker in What happens physiologically when we brace ourselves for things? by bee1413

I realized I wrote that poorly. Let me clarify... Your body still needs oxygen, in fact it uses more. But your blood pressure goes up, muscles get more oxygenated blood, really a host of things happen to make your body way more efficient at transporting oxygen to the parts that are going to "protect you". That's why you'll see somebody who is typically a sloth bust into an Olympic run when a gun goes off near him or a loud noise scares him good. All that adrenaline maximized oxygen flow and glucose processing and turned that Twinkie eater into a track star for a few moments.

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DelightfullyRosy t1_j3hky3r wrote

Reply to comment by M-3X in How long does HIV remain infectious outside the body? by Terradubia

sometimes! i don’t know specifically for HIV how many particles are needed to infect. but i know for norovirus it’s something wild like only 10 viral particles need to enter the body to cause infection. this is the same for shigella, about 10ish bacterial cells. comparing to salmonella which is like thousands of cells (different sources say different numbers but on average about 10^5 or 10^6 cells: 100,000 or 1,000,000). in the case of these 3 pathogens it’s different because they’re gastrointestinal & i think the number of cells has to do with survival in stomach acid (part of your immune system, called the innate part) but my point for saying all of this is that yes, at some point for all pathogens your immune system will kill all of the particles but the issue is when there are too many particles at once for it to kill. 1 particle of a pathogen, yeah you got this. 2 particles? probably. 100 particles? not so sure. because another factor that comes into play is how good the pathogen is at evading the immune system. for the example i used above, shigella isn’t as affected by stomach acid as salmonella is, so shigella can “evade” by surviving and entering your intestine which is why only small numbers are needed to infect. on the other hand salmonella isn’t so good at evading the immune system/the stomach acid, so you need like a hundred thousand cells because sooo many of them are going to be killed by the stomach acid that with a higher number of cells, there are higher odds that a few cells will survive and make it through to your intestine. with lower numbers of cells entering the stomach, the odds are higher that the stomach acid will destroy all the cells and none will make it to your intestine, therefore you do not get sick bc your immune system/stomach acid worked!

i hope this helps explain the general concept even though i could not focus on HIV specifically. feel free to ask me any more questions (even if you think they’re lame - they’re not!! i love explaining and talking about micro stuff!!) and if there is something specific you really want to know i can help you find good sources that explain it

EDIT: i also forgot to add because i haven’t seen it really spelled out in the few comments i’ve read. but for pathogens living on surfaces, if the surface is “clean” it’s generally harder for a bug to survive a long time (“long time” being different for each pathogen) but if a surface is “dirty” it is generally easier. so by dirty, i mean if there is actual dirt or biological material, like dried blood or body fluids. so to help you picture it, at home let’s say you want to disinfect your stove top but there is dried food all crusted on. that is a “dirty” surface because of the dry food. and in order to disinfect, you need to first clean the surface to remove all crusty food & once you do that it is a “clean” surface. then you can disinfect properly. the reason you can’t disinfect straight away on a dirty surface is that whatever Stuff is on there can provide some sort of environment or nutrient etc to pathogens and it’s hard to penetrate the Stuff with disinfectant, so you first need to clean to remove the Stuff which removes a safe spot for the pathogen, and then when you disinfect there is no Stuff to penetrate and you can ensure disinfectant remains on the surface for the given contact time

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Foxs-In-A-Trenchcoat t1_j3hiwqc wrote

Reply to How does the spindle apparatus know what to do during cell division? by ihaveredhaironmyhead

"Weak" chemical interactions like dispersion forces. Chemical interactions control all molecular positions and functions in a cell. Behind this, it's all controlled by Gibb's free energy, enthalpy, and entropy.

These forces partition molecules to certain locations to control whether or not they function. Membraneless organelles are a fairly new discovery where people are seeing how important noncovalent interactions are.

Ultimately, every chemical reaction or noncovalent interaction that has ever happened from the beginning of time had to happen because it was thermodynamically favorable.

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ChornWork2 t1_j3hiwbj wrote

Reply to comment by cristiano-potato in How long does HIV remain infectious outside the body? by Terradubia

General answers and advice is less restrictive than what is technically possible. I'll give a personal example. I have HSV2, but orally not on my genitals. Was trying to figure out the risk of spreading it oral to oral. General advice is not unless outbreak, but technically possible since research shows can have virus present without outbreak. Notably with oral HSV2 another outbreak is almost guaranteed not to happen (and I've never had one since and it's been about 10yrs).

In any event, I wasn't satisfied with the potential discrepancy and actually emailed researchers listed on papers and was pleasantly surprised by most responding. My take away was that while none wanted to give me advice beyond referring to official sources (which for HSV2 is generally limited to genital contact), because can't rule out oral to oral happening. But they did note that if I ever thought I spread it via oral-to-oral to reach out to them because it would be a case they'd like to look into...

So outlier risk they can't rule out, but one that people shouldn't factor into their ordinary lives. So I have disclosed to all sexual partners (in certain cases preempting their status as a sexual partner, lol), but not a risk I consider otherwise with caveat of anyone I think may be immunocompromised.

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xanthraxoid t1_j3hflwd wrote

Reply to comment by argenbar in Are gaiters at least partially effective at blocking aerosols? by Lokarin

> it would probably be similarly effective for personal protection.

Unlikely. The virus containing moisture particles are pretty large and easy to catch when you exhale them, but they rapidly dry out and become very small - small enough to make catching them much harder.

I would assume that a neck gaiter would be very much like a face mask on that front, though obviously much less effective because of not being designed / tested for the purpose.

More info here - I recommend having sci-hub to hand, too.

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daywalkker t1_j3he09f wrote

Reply to How come there are so many indentations on the moon that are so close to perfectly round that they look as if they could have been be man-made? by mightierthor

Just because something is round doesn't mean it is man-made. Planets are spherical or oblate spheroid and they surely aren't man-made. Man-made is not the only way to attain perfect, nearly perfect, or complex structures.

Hell, look at complex life on our planet. It is far more advanced than anything man has ever made and it is 100% natural.

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