Recent comments in /f/askscience
ilovemybrownies t1_jefu3on wrote
Reply to comment by Iron_Garuda in What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
Thankfully if you stop using long enough it does seem to go away for many people. Some studies suggest it's reversible in the sense that your pain receptors may "reset" their tolerance after roughly 5-6 months of abstinence from the drug. Sometimes doctors have success just rotating opioids in their patient's med schedule and using other pain meds in-between.
[deleted] t1_jefso1f wrote
Iron_Garuda t1_jefsh2f wrote
Reply to comment by ilovemybrownies in What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
Are you aware if it’s a reversible phenomenon?
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dandan_oficial t1_jefqwma wrote
Reply to comment by Foxs-In-A-Trenchcoat in What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
which thinking about it makes sense, because when the body is too insensitive to things it might try to feel them again, and for that it'll develop more pain receptors... Just a thought.
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Foxs-In-A-Trenchcoat t1_jefl3mo wrote
Reply to comment by ilovemybrownies in What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
I heard they actually grow more pain receptors the longer they're on opioids.
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mfb- t1_jefh2nx wrote
Reply to comment by kompootor in Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science by AutoModerator
I'm not sure how you got the dipole moment. The uniform component of Earth's magnetic field is only changing the energy of the arrangement, the force comes from the inhomogeneity. As an order of magnitude estimate, the force will be F = B_1 V B_E / (R_E mu_0) with B_1 and B_E being the two magnetic fields, V being the volume of the steel block and R_E being the radius of Earth (as scale of the variation of Earth's magnetic field). mu_0 is the vacuum permeability. Coincidentally, it's comparable to the number you got, 10^(-5) N.
If we don't divide by the radius of Earth we get a (sort of) potential energy, which is tens of joule. Completely negligible compared to hundreds of gigajoule of kinetic energy.
svenx t1_jefg3rf wrote
Reply to What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
Narcan (Naloxone) blocks endorphin receptors, preventing endorphins (your body's natural pain killer - "endogenous morphine") from doing its job. So while it doesn't directly increase pain, it keeps your body from taking its normal steps to *reduce* that pain, leading to greater overall pain perception.
[deleted] t1_jefedmd wrote
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kompootor t1_jefdd2k wrote
Reply to comment by Flyingtorooftop03 in Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science by AutoModerator
Are you talking about at the time of Earth's formation, as in, early Earth gets a magnetic field, which attracts more iron and nickel to the core as it's forming? That seems unlikely, since the Earth's magnetic field is caused by convection currents of iron around the core, which requires the immense heat and pressure of an entire rocky planet around it to work. (But I don't know.)
Are you instead asking whether metal would be attracted to Earth since after Earth's formation through today? In short, yes. Our magnetic field has components both inward toward the core and parallel to the Earth's surface. On the surface we humans mostly can see the effects of the magnetic field as exerting a force on a compass needle. The needle is very light, carefully balanced, and shielded from the air so that there are as few additional forces involved that could overwhelm or resist that caused by Earth's magnetic field. Also, a compass needle is magnetized so that it aligns correctly and at maximum force with magnetic North. In principle a non-magnetized iron (or other ferromagnetic) needle can also be used in a compass, following recalibration. [See a StackX explanation on this, though the answer appears to be interpreting the necessary energy as that needed to permanently magnetize a needle, as opposed to simply the Zeeman energy, which is a net gain when the sum of alignment directions of its tiny component magnetized crystals with respect the external magnetic field is calculated. Thus as long as resistance in the compass chamber is minimal, the needle should eventually align. Magnetite as lodestone, incompletely magnetized, was used in this way.]
Note that in orbit the magnetic field is only about half as strong as on the surface (where it is already quite weak by human observation standards), and it decreases steeply further out, but low orbit is perhaps the first place where you might first think of a free unmagnetized iron or nickel (a ferromagnetic metal) object being noticeably affected by Earth's magnetic field. There's a lot of subtleties here that I'm sure I'll miss, but let's try a calculation: taking magnetic saturation into account (thanks u/mfb- ), the max magnetization of steel is 2 T, and if we have a 1 m^3 block of steel in space then that's a magnetic dipole moment of 2 A m^2, so with a magnetic field in orbit of 35 * 10^(-6) T, the forces experienced in orbit are at max 7 * 10^(-5) N. Compare this to, say, the total drag forces in orbit, say at ISS orbit at 400 km (p. 14) ~ .001 dynes/cm^2 * 100^2 cm^2 * 10^(-5) N/dyne = 10^(-4) N. So at most, the magnetic forces on this (unrealistically) enormous metal block in orbit would be of comparable magnitude, a bit less, than the not insignificant drag at the ISS, which is more significant than I expected if I took into account everything needed (which is a big "if").
[deleted] t1_jefcvyr wrote
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Oony_oon t1_jefcmjc wrote
Reply to comment by Shark-Whisperer in How does toothpaste fluoride make teeth stronger topically? by Gilem_Meklos
It's a bit of a stretch for this article to say dental caries has a prevalence of 100% of people. (Somewhat technically correct, but really stretching it and trying to make a dramatic effect)
For it to be called dental caries, there has to be a bacteriological element to it. Meaning the demineralisation is due to acid-producing plaque bacteria.
Yes, if you were to hypothetically extract ALL the teeth of a random sample of people and examine every surface of those teeth, you'll find that everyone will likely have a spot on a tooth somewhere that has lost some mineral, even if it's a tiny, minuscule area. So what?
It's certainly near 100%, but I'd disagree with the idea that absolutely everyone has active decay in their mouth and is suffering the effects of it. As long as you're alive and eating food, there will be *some* demineralisation of teeth, but in most cases the minerals reconstitute back into the tooth shortly after. There's always a constant cycle of demineralisation and remineralisation every day, and it's not always due to bacteria. A lot of fruits have a pH below the critical pH for demineralisation.
Sure, at some point in anyone's life, the demineralisation can outstrip remineralisation and there is a net loss of mineral from a certain tooth surface. For the demineralisation to be clinically significant (i.e. detectable by visual or radiographic means), it takes months or years to develop. And if it's an early stage, shallow lesion, there's still a good chance for it to remineralise completely if the causative factors are addressed.
Bones are also in a constant state of resorption and deposition. When someone's bone density goes below a certain threshold (T score -2.5), suffered a pathological fracture, or has a combination of factors that puts them at high risk of pathological fracture, only then can it be called osteoporosis.
Whereas someone can technically be diagnosed with dental caries the moment a small spot of demineralisation is detected, regardless of where it is in the continuum of the demineralisation-remineralisation dynamic.
If the diagnostic criteria for osteoporosis were changed to "detection of any resorptive loss of bone mineral in any bone in the body", you could then technically say that 100% of people have osteoporosis too.
ECatPlay t1_jefce04 wrote
Reply to comment by Martinjg_ge in During Electrolysis of Water, what happens to oxygen at the cathode and hydrogen at the anode? by Martinjg_ge
> i always thought of water as a pot of rice, of fixed, unchangable, determined molecules
Well you aren't wrong, it all depends on the timescale you are thinking about.
Water molecules are constantly in motion. This is what 1 picosecond of movement in a water droplet at 0 C looks like. They do move around a lot, and a lot of collisions take place in between even diffusion controlled reactions like H-abstraction (timescale 10^(-9) sec).
But relative to molecular vibrations, for instance, they are barely moving at all. Bond stretching vibrations (O-H stretch timescale ~10^(-13) sec), are orders of magnitude faster than collisions. And electronic transitions are several orders of magnitude faster than that (timescale ~10^(-15) sec), so thinking of the atoms and molecules as "fixed" in space would be an excellent picture of them on that timescale. Thinking about an electrical conductor, instead of an H^+ transfer medium, for instance.
derconsi t1_jefv5wv wrote
Reply to What is known about pain enhancement? For instance, are there drugs that are the opposite of analgesics? If so, what are they and how do they work with neurons/neurotransmitters? by DollyPartWithOn
Got a bit of knowledge in that department, not enough for credibility tho so Im just sharing my thoughts (in a foreign language, bare with me)
the Sedatives and Analgetics I am Aware of essentially block or slow down the pathway between nerves.
As the Nervous system (divided in two areas: Central NS, the part within your spine and your brain and peripheral NS, all other nerves) uses two one lane streets to work each area (one leading to eg your finger from your brain (motoric) and one the other way around (sensoric) uses transmitters to work.
one could for example try toincrease the production, storage capacity or contact gates of those. That might increase the flat value of sent impulses we interpret as eg pain.
I have to state however that our body has keyholes to those keys all over its body and therefore reacts in most parts of the body to most transmitting agents
(EG adrenaline works the do called "Adrenoceptors" Devided in Alpha1, Alpha2, Beta1 and Beta2 (there seems to be a third pairing Gamma, but as far as I know we havent really understood that one yet). Those are all over our body, so if you inhale Adrenaline to treat eg an anaphylactic shock your lungs will experience the effects first and foremost, but all receptors in your body will take part)
without being capable to explicitly only target the sensoric part of the nervous system the brain would experience an overflow of information, comming from every single nervous cell in our body exposed to the transmitter, wich would probably enforce a reaction similar to an epileptic episode.