Recent comments in /f/askscience

sighthoundman t1_j49fby3 wrote

Reply to comment by leSchaf in where does epinephrine comes from? The one used for people with allergies because Google only says It comes from glands so I don't understand if it's donated or sintethized by other means. by SALAMI_21

>I don't actually have first hand knowledge but slaughtering livestock just for adrenal glands simply makes no sense.

And yet.

We (as in humans, not as in you and me) slaughter rhinos for their horns, sharks for their fins, (both of those are "traditional medicine") and elephants for their teeth (to make trinkets and piano keys).

Bezoars (most frequently gallstones but sometimes other types of spherical objects from an animal's intestines) were popular in Europe from the 11th to the 17th centuries. Unicorn bezoars could cure anything.

Only the piano keys is /s. Everything else went away when we adopted a more scientific approach to life (/s), but was once believed to be true.

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Otherwise-Way-1176 t1_j498odh wrote

Reply to comment by [deleted] in How do we know that dark matter isn't just ordinary matter our instruments can't detect? by jmite

You haven’t answered the OP’s question at all.

> Then consider that flight alone was thought of as impossible less than 150 years ago.

No, flight was not thought of as impossible 150 years ago. It was very obviously possible, because birds, insects, and bats all fly. People knew that flight was possible.

150 years ago, we didn’t know how to build a machine that could carry humans into the air. We simply didn’t yet know how to engineer the solution - doesn’t mean we thought it was impossible.

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TranscendentMadMan t1_j48yrn1 wrote

Reply to What exactly is the process when someone "trains" an AI to learn or do something? by kindofaboveaverage

As others have stated, these days "AI" typically refers to "Artificial Neural Networks". As the name suggests, they are meant to mimic one of the trillions of neural networks found in the brains of animals/people.

Like a budding, miniature brain, you need to train/educate it by giving it a variety of situations (inputs) and seeing how it responds (outputs). Then, you reward or punish it (positive/negative reinforcement) based on its behavior. Naturally, there are different methods/algorithms on how to apply that reinforcement. (I once read a paper where the authors tried training an ANN using a genetic algorithm! (Which is a different kind of AI.))

You could almost think of it as showing a toddler flash cards of cats and dogs and giving them a candy for every right answer. But, what happens if the deck does not have any fox cards and then they see a fox, will they identify it as a dog or as a cat?

The documentary on Netflix, "Coded Bias", highlights the dangers of AI and the importance of having good training data. (eg. Having a deck of flash cards that includes foxes.) My only issue with the movie is that it does not discuss any positive uses of AI, which there are some.

If you want to experiment with AI first-hand, I found Microsoft's ML.Net surprisingly easy to use. It was as easy as give it a text doc and within minutes it will give you an AI to play with.

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Electronic-Jury-3579 t1_j48vtjl wrote

Reply to comment by PEVEI in where does epinephrine comes from? The one used for people with allergies because Google only says It comes from glands so I don't understand if it's donated or sintethized by other means. by SALAMI_21

So if the environmentalists/vegans/others that don't want farm meat, fully shutdown farming animals for food, sounds like the medical supply of things like this are at risk of not existing anymore. What's healthcare going to look like. Such a balancing act.

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Ok-Arm-362 t1_j48uhy1 wrote

Reply to How do drug trials determine dosage time limits for medications? by dante662

You are actually asking 2 questions. The frequency of dosing for effect, and maximum dosing to avoid problems. The labeling for the latter is not based solely on pharmacokinetic data. Rather, a mix of data, opinion and (at least in the US) the FDA's assumption that all users are dumb as a bag of hammers.

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Furrypocketpussy t1_j48op3x wrote

Reply to What happens to a photon after it hits my eyeball? by NJdevil202

The back of your eye is packed with rods and cones (mostly rods, about 120 million of them vs 6m cones) and the photon is absorbed by them. Inside rods you have stacks of proteins called optic disks, that have rhodopsin in them, which has a small molecule called 11-cis retinal. When light comes through the pupil and hits the rod, some of it will hit the rhodopsin and cause a change in retinal to 11-trans retinal. This change in shape will cause a cascade that closes sodium channels on the rod and essentially turns the cell "off". The turning off of the rod will turn on a bipolar cell which then turns on a retinal ganglion cell that finally sends a signal via the optic nerve to the brain

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CrateDane t1_j48lc5y wrote

Reply to comment by Minute_Farmer in Is there physical differences between blood types? by terrip_t1

> > > > > The reason it's important to know this is because your body recognizes your cells by recognizing the cell surface antigens on your cells.

Well, mostly they don't recognize your own cells, they recognize anything foreign.

There are a few exceptions like NK cells recognizing MHC I from your own cells. But that's not involved here.

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CrateDane t1_j48indt wrote

Reply to comment by deviantbono in What happens to a photon after it hits my eyeball? by NJdevil202

The detector itself is technically part of the brain, as is all of the retina. It's true that the response of the cells that detect light is the opposite of normal neuron activation - hyperpolarization instead of depolarization. That gets swapped around before the signal leaves the retina though, along with some early processing taking place.

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