Why are some surfaces erasable after use of dry-erase (non-permanent) markers while some are not? |
- Why are some surfaces erasable after use of dry-erase (non-permanent) markers while some are not?
- How do tetanus vaccines (boosters) work?
- Why does introducing Mg ions help prevent limescale buildup?
- In creating a nuclear missile, how much of the difficulty is due to the difficulty of refining and obtaining the U-235 needed for fission?
- Were the Chernobyl operators just really unlucky in regards to the Xenon burnoff?
- How do spiders survive inside people's homes?
- What is the difference between "Newtonian" and "isotropic" in fluid mechanics?
- Can we figure out the properties of a material just by knowing how it is atomically structured?
- Why do ashlayers get saved in the geological record?
- Did the Diplodocus actually knock down trees in their search of ferns?
- Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology
- What's the benefit of the giant Magellan telescope mirror size vs the large array of smaller mirrors on the European extremely large telescope?
- Do animals generally have a dominant side/preferred side like humans do with our being left or right handed, for example?
- Why can't we deduce the volume of a black hole in general relativity from it's mass ?
| Why are some surfaces erasable after use of dry-erase (non-permanent) markers while some are not? Posted: 31 Oct 2019 01:41 AM PDT What gives the surface of an object this quality? (Dry-erase markers being erasable from surface) Glossiness? Polarity? I am searching the internet but I can't find a certain answer [link] [comments]  |
| How do tetanus vaccines (boosters) work? Posted: 31 Oct 2019 01:12 AM PDT A vaccine causes an active immune response, which leaves behind memory cells and results in immunity. I understand the concept of getting a "booster" some time after to keep the immunity, but why do people need tetanus shots after getting a puncture wound. If the antigens are already in the body, is a response to the vaccine really going to help deal with a pathogen that has already breached the external defense? Or does the tetanus booster contain antibodies to help fight the infection? [link] [comments]  |
| Why does introducing Mg ions help prevent limescale buildup? Posted: 31 Oct 2019 05:34 AM PDT I bought a new water filter that supposedly adds Mg ions to the filtered water. Do resin filters just remove too many ions? Is it just a gimmick? [link] [comments]  |
| Posted: 31 Oct 2019 01:10 AM PDT |
| Were the Chernobyl operators just really unlucky in regards to the Xenon burnoff? Posted: 30 Oct 2019 07:06 PM PDT We have all seen that tv scene, where Legasov explained what went on in the last seconds of reactor 4: The feed water was shut off, the uncooled water boiled away (increasing reactivity), the Xenon got burned off (increasing reactivity even more), and finally the insertion of the control rods let the reactor go promptly supercritical (i.e.: "boom"). My question is: Why did the Xenon get burned off in just these crucial seconds? Xenon burnoff is proportional to neutron flow, which again is proportional to reactor power. Sure, reactor power did increase in these seconds, but even if we assume a reactor power of 10 GW during these 10 seconds, the total burnoff should have been the same as would have happened, if the previous level of 200 MW had been kept for an additional 500 seconds, i.e. eight minutes. So, did the Xenon concentration by a stroke of ridiculously bad luck sink below some important threshold just during the power excursion? Or was the Xenon poisoning's importance simply that it forced the crew do conduct their test under otherwise extremely volatile operating conditions, and its contribution to the actual accident was negligible? [link] [comments]  |
| How do spiders survive inside people's homes? Posted: 30 Oct 2019 07:19 AM PDT I just don't see how there is enough food inside a clean house vs. outdoors, yet so many spiders still set up shop inside attics, basements, and living spaces. How do they not only survive with such a lack of food available, but also seem to grow and thrive? [link] [comments]  |
| What is the difference between "Newtonian" and "isotropic" in fluid mechanics? Posted: 30 Oct 2019 08:23 PM PDT In my intermediate fluid mechanics course, the viscous stress tensor was introduced, with associated expressions for each shear stress. I realized that, just as with solid mechanics, the viscosity could vary with direction in an anisotropic substance; however, when I asked the professor about the possibility of Newtonian anisotropic fluids, I was told that that this normally does not occur (that is, "Newtonian" implies "isotropic"). However, this does not correspond with my understanding of the two concepts. My impression is that "Newtonian" implies a viscosity that is independent of the applied shear stress (that is, not having any description of spatial dependence), while "isotropic" implies that properties are invariant regardless of the direction of travel. Which of these is correct? [link] [comments]  |
| Can we figure out the properties of a material just by knowing how it is atomically structured? Posted: 30 Oct 2019 05:32 AM PDT Given the atomic structure of an element, is there a way to deduct that elements properties? Can you theoretically figure out the color, bendablity, etc. of an element just by knowing how it is atomically structured? How could this be done? [link] [comments]  |
| Why do ashlayers get saved in the geological record? Posted: 30 Oct 2019 06:53 AM PDT Shouldn't something need to be present on the surface of the ground for a very long period of time to be shown in rock or ice layers etc? Like even if ash was a metre thick, wouldn't it have to sit undisturbed for like 100 or 500 years or something to leave a meaningful stain. Surely if it took like 100 years though, for example, it would just be so dispersed with dirt and whatever else to be virtually invisible. Clearly that isn't the case though, as ash layers exist. So what is happening? [link] [comments]  |
| Did the Diplodocus actually knock down trees in their search of ferns? Posted: 30 Oct 2019 05:45 AM PDT I was just rewatching Walking With Dinosaurs, I probably haven't seen it in 10 years, it's fascinating. But there was one part in episode 2 where they claim that the Diplodocus would knock down trees with their astonishing weight in search of the ferns that grew in between the trees in a forest. I found that absolutely incredible, and I googled it to make sure it was an accepted fact but I couldn't really find a source. Can anyone help? [link] [comments]  |
| Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology Posted: 30 Oct 2019 08:09 AM PDT Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Biology, Chemistry, Neuroscience, Medicine, Psychology Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Asking Questions: Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Answering Questions: Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience. If you would like to become a member of the AskScience panel, please refer to the information provided here. Past AskAnythingWednesday posts can be found here. Ask away! [link] [comments]  |
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| Why can't we deduce the volume of a black hole in general relativity from it's mass ? Posted: 29 Oct 2019 08:08 PM PDT I came across this : The shape of a Schwarzschild black hole is that of a sphere. We might be tempted to use our ordinary intuition about geometry, and deduce the volume of a Schwarzschild black hole This is, however, not necessarily the case. It turns out that the volume of a black hole is not a well-defined notion in general relativity. The reason is that general relativity is a geometric theory of a four-dimensional spacetime, that is, three dimensions of space and one dimension of time. In order to specify a spatial volume, one has to specify a specific moment in time. [link] [comments]  |
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