| Why does the order parameter of nematic liquids become zero for isotropic liquids? Posted: 12 Dec 2018 02:15 AM PST Hello The order parameter for nematic liquids ( liquid crystals) is
S = 1/2 <3cos²q-1> according to multiple sources. q being the average angle between the molecular axis and the directional axis of the liquid. I get that for a perfectly ordered liquid q = 0 ( all molecules point in the direction of the directional axis), then you get 1/2*(3-1) = 1. Which is an expected outcome, as S = 1 for perfectly ordered liquids. However, the sources say that for an unordered liquid S becomes zero. Doing some maths reveals that the average angle would then be about 55°. Why would a liquid with an average of angle of 55° be 'perfectly unordered' but a liquid with an average angle of 50° not?
So in short: why would S become zero for isotropic liquids? Thank you! submitted by /u/lolspek [link] [comments] |
| What portion of long term treatment resistant depression patients never really get better? Posted: 11 Dec 2018 07:46 PM PST https://www.webmd.com/depression/guide/treatment-resistant-depression-what-is-treatment-resistant-depression "Living With Treatment-Resistant Depression Life with depression is hard, but treatment-resistant depression can be especially brutal. When one treatment after another doesn't help, you can lose hope that you'll ever feel better. All your efforts -- the doctor's visits, the medication trials, the therapy sessions -- might seem like a waste. But they haven't been a waste. Arriving at the right treatment for depression can take time. It can take some trial and error. Look at it this way: if you try a particular treatment and it doesn't help, you're that much closer to finding the one that will make you feel better. Whatever you do, don't settle. Don't give up and accept the symptoms of depression. Remember, the longer a depression goes on, the harder it may be to treat. Go back to your doctor and see if there's something else you can try. There are so many good treatments for depression out there. You just need to find the right one for you." This seems to imply that all cases of depression can eventually be effectively treated. That seems dubious to me. What portion of long term treatment resistant depression patients never really get better? What portion just keep on trying different different meds until they die of natural causes? What portion choose to end their lives? What portion eventually choose to discontinue treatment, but continue to suffer? What portion discontinue treatment, but feel better? Any other possibilities I'm missing? How well can this even be measured and known? submitted by /u/benjaminikuta [link] [comments] |
| Where in the night sky is Voyager 1 headed, in the long term? Posted: 11 Dec 2018 04:30 PM PST From this skypath of Voyager 1's trajectory, generated from NASA data, it looks like Voyager 1's location in the night sky is asymptotically approaching a point somewhere in the triangle formed by Rasalhague (α Ophiuchi), Rasalgethi (α Herculis), and HIP 84671 (e Ophiuchi). Will Voyager keep approaching this point indefinitely? Or are there any long-term effects that will cause its position in the sky to drift over the coming hundreds or thousands of years--a time scale long enough that these effects haven't been observed yet, but short enough that the stars will stay in roughly the same places? submitted by /u/dpitch40 [link] [comments] |
| Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science Posted: 12 Dec 2018 07:11 AM PST Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Physics, Astronomy, Earth and Planetary Science 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! submitted by /u/AutoModerator [link] [comments] |
| Do any other species besides humans bury their dead? Posted: 12 Dec 2018 06:38 AM PST |
| Are there animals that tend to, or protective of, their grandchildren? Posted: 12 Dec 2018 06:19 AM PST |
| How can electric devices and other sources of rather large voltages be lethal in water if the flow of electricity follows the path of least resistance? Posted: 11 Dec 2018 03:12 PM PST So after thinking about this for a while i thought i should ask why, say 230V common electricity network (atleast in Europe it is) can electrocute someone to death in a bathtub even though both of the electrodes are very close to each other without a human in between them? Shouldn't the flow of electrons just pass through the path that has the least resistance (i would believe it would be directly between the electrodes in a homogenous electrolyte) without harming the person in the bathtub? submitted by /u/Ollemeister_ [link] [comments] |
| How is air recirculated in submarines, spacecraft, and other similar structures? And why has that tech not been applied to things such as Scuba tanks? Posted: 12 Dec 2018 05:30 AM PST |
| Not all cigarette-naive individuals have the same experiences upon smoking. What role do MAOIs play in addiction and pleasure of cigarettes for different brains, and can we use this as a diagnostic tool for distinguishing between otherwise similar disorders and to guide prescriptions of medication? Posted: 12 Dec 2018 05:22 AM PST Some people become addicted, while others don't. Some people experience strong headspins and nausea during their first few cigarettes, while others don't. While these could be mostly differences in mindset, lifestyle or puff speed, it's well established that there's variation in brain structures and our specific chemistries, such as alcohol metabolism or different responses to prescription medications. The likelihood of an individual adopting a new addiction is increased through down-regulation of brain regions from existing addictions and other aspects of lifestyle such as stress and the absence of physical activity, social interaction, etc. While some demographics are more prone to developing a substance use disorder (such as those with borderline personality disorder and adolescents) , they also tend to have the traits mentioned above which prime them for adopting addictions. Given that nicotine has it's addictiveness enhanced by MAOIs, and SSRIs like bupropion are used as smoking cessations, could we administer cigarettes to patients to figure out which anti-depressents may work, or to distinguish between disorders with similar behaviours but very different chemistries? For instance in distinguishing whether someone has OCD or ADHD, hypothyroidism or chronic fatigue syndrome, cyclothymia vs seasonal affective disorder, etc. submitted by /u/ThrowawayBrisvegas [link] [comments] |
| How is job growth calculated? What kind of factors are accounted for? Posted: 12 Dec 2018 04:17 AM PST Im curious how statisticians calculate how much a job market will grow or decrease in the future. Where do sites like bls.gov get their info submitted by /u/Gofishyex [link] [comments] |
| How and why does high blood volume/pressure pose a risk to health? Posted: 12 Dec 2018 01:45 AM PST Hi there. I am looking to understand how high blood pressure or high blood volume alone (with no atherosclerosis or other signs of CVD) can damage health. I am interested in the specific physiological mechanisms (if any) through which chronic high blood pressure damages any part of the human body. Thank you! submitted by /u/4f14-5d4-6s2 [link] [comments] |
| In a vacuum, all objects, regardless of mass, fall at the same rate. However, since objects with less mass have less inertia and therefore they are affected more by the same amount of force, why don't object with less mass fall at a greater rate in a vacuum than more massive objects? Posted: 11 Dec 2018 05:19 PM PST |
| Why does a frozen turkey defrost faster in water than in the fridge? Posted: 11 Dec 2018 02:43 PM PST When defrosting a turkey in cold water it takes approx. 30 minutes per pound, yet in the fridge it takes approx. 6 hours per pound. Why so much faster in water? submitted by /u/KathyOlesky [link] [comments] |
| Why can insulated containers, such as a thermos, keep a liquid cold for longer than it can keep a liquid hot? Posted: 11 Dec 2018 08:40 AM PST |
| Are Diamonds originally highly pressurized coal? And if so, Are there any other minerals that can undergo the same change to something much harder than itself? Posted: 11 Dec 2018 09:04 AM PST |
| Do we know what percentage of the stars visible today don't exist anymore? Posted: 11 Dec 2018 11:25 AM PST When I say visible, I mean visible by any means (i.e. all kinds of telescopes). submitted by /u/asmj [link] [comments] |
| What is the most carbon-dense plant? Posted: 11 Dec 2018 07:49 AM PST For individuals looking to combat climate change, what plant(s) would give you the biggest bang for your buck/space? What plant(s) are the most efficient at storing carbon? submitted by /u/thgildea [link] [comments] |
| Are the fundamental constants really constants ? Posted: 11 Dec 2018 01:31 PM PST I was wondering if the fundamental constants (such as the Planck constant, gravitational constant etc) are really constants or a function of "time" (if we could visualize one more time like axis along which these constants are a function of) ? If so, what are its implications ? If not, how do we prove that they are really constants in a sense and that they don't vary/ evolve ? I am curious what research has been done in this regard. submitted by /u/aaditya314159 [link] [comments] |
