Why do so many medicines require you to stop eating grapefruit? | AskScience Blog

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Wednesday, May 17, 2017

Why do so many medicines require you to stop eating grapefruit?

Why do so many medicines require you to stop eating grapefruit?

Why do so many medicines require you to stop eating grapefruit?

Posted: 16 May 2017 02:03 PM PDT

Is a single atom able to cast a shadow?

Posted: 17 May 2017 03:24 AM PDT

[neuroscience]Is there any limit as to how much information that the human brain can hold?

Posted: 16 May 2017 06:58 PM PDT

Is there any theoretical limit as to how much information that the human brain can hold?

What would happen if someone reached that limit?

submitted by /u/Der_Ist
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Why is NASA's James Webb telescope built out of hexagonal panels for its mirror? Why is the mirror not a curved surface, and why were hexagons chosen over triangles or octagons etc.? Why does the Hubble telescope (seem to) not require this geometry?

Posted: 16 May 2017 10:02 PM PDT

Why is there a blip in lift at the stall angle in this CFD calculation?

Posted: 17 May 2017 03:55 AM PDT

As you can see from this image, there is a blip in lift around the stall angle for the wing we ran through a CFD program. We tested around 17-20 degrees multiple times and still saw that the lift went down, then up, then dropped off again as it stalled.

Is there a reason for the lift dropping off, then spiking again? Is it because of something to do with the flow detaching at a certain angle, then managing to reattach before detaching again? Is it just an expected error when running this sort of simulation through a computer program, or did we simply not test a wide enough range around the stall angle to get enough data to show a relatively steady drop off?

Lots of questions, I'm just puzzled as to why this happened. Any help would be greatly appreciated!

EDIT: My comment on a x-post:

Yeah, vortices being generated on the leading edge would be my guess as it's the only seemingly possible way for the flow to reattach after detaching at a slightly lower AoA, which would explain the lift spike.

The only comparable example I can come up with is the Vortex Lift effect on delta wings, which causes an increase in lift at high AoA due to vortices forming on the leading edge. However, this happens because the leading edge is sharp, so I didn't think this was possible for a ~NACA 0021 profile.

For delta wings: "In general, this vortex flow results in an increase in lift associated with the upper-surface pressures induced by the vortex and an increase in drag resulting from the loss of leading-edge suction." The effect is how delta wings maintain low speeds / high AoA as the vortices increase the stall angle.

No way of testing it, but it's a NACA 0021 profile so I thought that this effect would be well documented if it existed on the profile. The only reason I can think it might not be documented is if this effect only happens at certain airspeeds and I happened to pick one that it does happen at.

It may just be an error with the CFD calculations, or it's just such a small effect that it's not credited elsewhere.

submitted by /u/Geotherm_alt
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How do virtual photons have a real influence?

Posted: 17 May 2017 06:00 AM PDT

My question is, if virtual photons are a mathematical book keeping tool, how do they play a real role in terms of Hawking radiation and vacuum energy?

Thanks!

submitted by /u/spk96
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Has an underground nuclear power plant ever been attempted, and would having a nuclear plant under ground mitigate the problems from a meltdown?

Posted: 16 May 2017 02:36 PM PDT

Can a linear accelerator be re-configured and used as a 'decelerator'?

Posted: 16 May 2017 06:23 PM PDT

Let's say one had a beam of charged particles moving at some speed, could they be slowed using a linear accelerator that is reconfigured to decelerate the particles? If it's simpler to think about this with defined 'packets' of charged particles, or particles that penetrate the 'decelerator' one at a time, then so be it.

submitted by /u/dbcollins
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Can neutrons be created by bombarding protons with electrons of high enough energy?

Posted: 16 May 2017 10:19 PM PDT

I'm aware that electron capture is this process, but it only occurs in nuclei where there is a lower energy decay state. What I haven't been able to find information on is if it's possible to fire an electron at a proton and convert the pair into an electron neutrino and neutron via the weak interaction, provided that the electron comes in with enough kinetic energy to account for the extra neutron mass. Since a similar process can take place with neutrinos transforming protons in nuclei via inverse beta decay, can electrons do something similar to bare protons (Hydrogen)?

submitted by /u/USI-9080
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Do different types of radiation have different effects?

Posted: 16 May 2017 04:56 PM PDT

I work in a nuclear power plant and we hear a lot about radiation doses and everything we do to keep it as low as reasonably achievable (ALARA).

During our training that everyone goes through we learn about different types of radiation: alpha, beta, gamma, and neutron. The focus is primarily on their penetrating power. Alpha is stopped by paper or skin, beta is blocked by plastic or aluminum, gamma is blocked by lead, and neutron radiation is blocked by concrete.

My question is do these different types of radiation have different effects on the body or are they just classified that way according to their shielding requirements?

submitted by /u/firedragonsrule
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Do astronauts in space have to push harder, in order to have a bowel movement?

Posted: 16 May 2017 06:30 PM PDT

If someone is walking down the road, is the air around them moving to avoid the person, or are they more like a knife cutting through the air?

Posted: 16 May 2017 12:28 PM PDT

Could a binary star system have a planet tidally locked to the baricenter?

Posted: 16 May 2017 02:48 PM PDT

What kills you when you burn to death?

Posted: 16 May 2017 12:46 PM PDT

Ok so the title sounds a bit silly but my question is,

What exactly is shutting down or ceasing to function when one burns to death? Obviously burning skin probably wouldn't kill you (not quickly anyway) and pain cant kill people AFAIK

So what is the fire doing to your body that causes you to die? is it heatstroke? does the fire burn through your skin and begin directly damaging organs? i was of the understanding fire killed you long before it was able to do this.

submitted by /u/ronduun
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If humans have only been around for about 100,000 years, then why did it take 95,000 years for us to do anything rememberable? Did our brains become more evolved in the last few thousand years?

Posted: 16 May 2017 07:49 PM PDT

The first major civilizations emerged around 5,000 years ago in places like the Middle East. All of recorded history fits approximately within the last 5,000-years. That leaves 95,000 of human history with nothing happening besides changes in the types of spears we used. Where are the wars of conquests and battles between the great empires from 50,000 years ago? Things like this didn't happen because it took 95,000 years to invent agriculture? Are humans from 50,000 years ago just the same as me? It seems amazing that for 95,000 years we did nothing, and just within the last 5,000 years we have gone from cave men to developing the technology to colonize other planets.

submitted by /u/some_dude_0123
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Why does being electrocuted (high voltage) cause a person to die?

Posted: 16 May 2017 08:58 PM PDT

In conversation with friends, we decided to look this up but after numerous pages on google, the most we got was that it stops your heart.

Why does it stop your heart? What prevents a human from being able to withstand higher voltage without dying?

Edit: grammar

submitted by /u/shirtlessaustin
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Can anyone give an intuitive explanation of gauge theory?

Posted: 16 May 2017 04:25 PM PDT

Is it possible to explain it in a way which is intuitive? I'm thinking something along the lines of how gravity is "an elastic sheet", but better than that, because that's a terrible analogy...

Thanks

submitted by /u/toolemeister
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[Physics] Can you fuse elementary particles and their antiparticles together, and what happens if you do?

Posted: 17 May 2017 04:51 AM PDT

I was wondering if you can fuse the following pairs: -Quarks/Antiquarks -Gluons/Antigluons -Electrons/Positrons

Do you still get a Photon for all of them or do you get a new particle. If you get a Photon, how could you create a new particle instead of a Photon?

I'm guessing that they have to collide to release their energy as Photons.

submitted by /u/Fleeingfromhumanity
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Is there an intuitive way of understanding the contraction mapping theorem?

Posted: 16 May 2017 05:59 PM PDT

How stable would elements in the island of stability be?

Posted: 16 May 2017 03:46 PM PDT

I'm asking because its my understanding that most superheavy elements last for inconceivably short amounts of time. Is it plausible that elements in the island can exist for thousands of years, or may it only be for a few seconds at best?

Following on, is there a possibility elements in the island could occur naturally somewhere in the universe?

submitted by /u/Khwarezm
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Could someone explain these equations?

Posted: 17 May 2017 02:41 AM PDT
vào lúc

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