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Friday, March 1, 2019

How does a chameleon change color?

How does a chameleon change color?


How does a chameleon change color?

Posted: 01 Mar 2019 04:25 AM PST

How do Photonic-Crystal Fibers work?

Posted: 01 Mar 2019 03:10 AM PST

I read that photonic-crystal fibers use diffraction to send multiple wavelengths of light down it's core so that multiple information can be transmitted at once. How exactly does diffraction happen with the solid and the hollow cores? Or have I misunderstood something, and it uses total internal reflection?

submitted by /u/Sts013
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How many atoms are split in a nuclear explosion?

Posted: 28 Feb 2019 10:47 PM PST

Because Tonsils are part of our immune system, does removing them have an impact on how often you get ill?

Posted: 28 Feb 2019 04:00 PM PST

Title sums it up, I'm aware it could also maybe impact how badly you get ill? (A normal cold lasting 2 weeks rather than 1)

Just wondering since I want to get mine removed :-)

submitted by /u/TheGoldenWaffle77
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If a blood type +A mother had an +AB baby, why doesn't the mother's developed anti-B antibodies attack the baby's blood as it contains a B antigen?

Posted: 28 Feb 2019 05:40 PM PST

If a Rh- mother has already developed anti-Rh antibodies, it will attack the red blood cells of their Rh+ baby, how come this doesn't apply to the A and B antigens? Regardless of the Rh antigens presence, shouldn't a mother with either an A or B antigen have its antibodies agglutinate with its respective antigen in the mother's AB baby?

submitted by /u/azangram
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Does the angle of reflection of light or other waves/particles vary with the spin of the said particle?

Posted: 01 Mar 2019 03:45 AM PST

If you put spin on a ball and it hits a surface the angle of the rebound changes based on the spin. Does the same apply to waves?

submitted by /u/LegitimateAdeptness
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Can you break or bend the rules of the "Fire Triangle"?

Posted: 28 Feb 2019 04:50 PM PST

In school, we were taught about the Fire Triangle; the three requirements for fire, those being fuel, heat, and oxygen. Being that this was middle school (I think) I assume this was a dumbed down or simplistic version. What are some ways these rules can be subverted? Is it possible to replace oxygen with another gas, or perhaps start a fire without heat?

submitted by /u/sbdallas
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If I have a device powered with 2 AA batteries, and the device is at 50% battery life, but I only have 1 AA battery left; would switching only one battery increase the battery life of the device?

Posted: 28 Feb 2019 01:48 PM PST

i.e. I have an xbox controller that is powered by 2 AA batteries. My controller is almost dead, at 20% battery life. If I switch out only one battery for a new one, does that increase the battery life of my xbox controller? Or does it remain at 20%?


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How does alcohol cause memory loss?

Posted: 28 Feb 2019 05:42 PM PST

How does alcohol cause memory loss?

I think I remember reading that it's not the BAC that causes it, per se, but rather, the rapid change in BAC; is that right?

submitted by /u/benjaminikuta
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How does this newly discovered half-twin mechanism work? How can one egg make two zygotes with two different sperm?

Posted: 28 Feb 2019 04:42 PM PST

When a star stops fusion reactions and collapses under its gravity, why does it explode outward?

Posted: 28 Feb 2019 12:23 PM PST

Also, I know some of the time not all the star explodes outward, its core is left behind and forms a white dwarf or a neutron star, how many solar masses does a star need to be to have all its mass launched into space when it goes supernova?

submitted by /u/WoodHeadPhones
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How do scientists measure how much a land mass moves every year?

Posted: 28 Feb 2019 12:05 PM PST

I saw a post on reddit stating that Hawaii moves 7.5cm closer to Alaska annually. How exactly do scientists come to this conclusion? Relative to the size of the Earth, 7.5cm is extremely finite.

How can they measure the distance it moved to this degree of accuracy given that the shorelines of most islands/continents are not always the same? What is the baseline for this measurement? What is the percentage of allowable error on something like this?

submitted by /u/holycornflake
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How did people initially find out that humans can survive with only one kidney?

Posted: 28 Feb 2019 12:20 PM PST

How do cells ask for more blood flow?

Posted: 28 Feb 2019 10:25 AM PST

If a cell or region of cells suddenly has an increased metabolic demand (for instance, if there's damage or increased stress to a certain area of the body), how do the cells stimulate more blood flow to the area?

submitted by /u/patchitup
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How many gluons are there in a proton?

Posted: 28 Feb 2019 12:23 PM PST

At high energies you get a colour glass condensate - but shouldn't the number of gluons in a proton be Lorentz invariant?

submitted by /u/neutrino_mark
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Why did the lakes and oceans of Mars disappear? Will the same thing happen to Earth?

Posted: 28 Feb 2019 11:41 AM PST

If our water mostly came from comets and such, wouldn't water be fairly common in other planets?

Posted: 28 Feb 2019 06:34 AM PST

Thursday, February 28, 2019

AskScience AMA Series: I'm Matthias Hebrok, and my lab has just published a breakthrough in making insulin-producing cells in a dish. My team at UCSF hopes to one day cure type 1 diabetes with transplantable beta cells made from human stem cells. AMA!

AskScience AMA Series: I'm Matthias Hebrok, and my lab has just published a breakthrough in making insulin-producing cells in a dish. My team at UCSF hopes to one day cure type 1 diabetes with transplantable beta cells made from human stem cells. AMA!


AskScience AMA Series: I'm Matthias Hebrok, and my lab has just published a breakthrough in making insulin-producing cells in a dish. My team at UCSF hopes to one day cure type 1 diabetes with transplantable beta cells made from human stem cells. AMA!

Posted: 28 Feb 2019 04:00 AM PST

I'm a stem cell biologist and director of the UCSF Diabetes Center. My lab aims to generate unlimited supplies of insulin-producing cells to unravel the mysteries of diabetes, with the ultimate goal of combating and defeating the disease. We just published a paper demonstrating for the first time the successful creation of mature, functional insulin-producing cells made from stem cells. Read more here: http://tiny.ucsf.edu/7uNbjg

My lab focuses on type 1 diabetes (T1D), which is the result of an autoimmune destruction of insulin-producing beta cells in the pancreas. Currently the only cure for T1D is a pancreas transplant or beta cell transplant, but these options are only available to the sickest patients, who then have to take immunosuppressants for the rest of their lives.

One of the biggest problems in diabetes research is that it is really hard to study these beta cells. They sit in the pancreas, an organ tucked away in the back of our bodies, that is hard to access in living people. We can obtain beta cells from cadaveric donors, but often the process of isolation affects the functionality of the cells. Therefore, one can argue that there is still a lot we do not understand about human beta cells, how they function under normal conditions, how they deteriorate in diabetes, and how one can possibly fix them.

By producing working beta cells in the lab, we've opened new doors to studying diabetes as well as new options for transplant therapies. Down the line, we hope to use genetic engineering technologies such as CRISPR to produce transplantable cells that don't require lifelong immune suppression.

I'm really excited about this work and looking forward to your questions. I'll be starting at 9am PST (12 ET, 16 UT). AMA!

submitted by /u/AskScienceModerator
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Why is static always black and white even on color TVs?

Posted: 27 Feb 2019 10:53 PM PST

How does allergy medication stop reactions to allergens, but not your immune responce to actual threats?

Posted: 27 Feb 2019 09:00 PM PST

Can you reverse cavities?

Posted: 28 Feb 2019 06:20 AM PST

I have some and I wonder if I can reverse it in some ways without going to the dentist.

submitted by /u/ezname
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What effects, if any, has the ingestion of BPA (and similar endocrinological disruptive chemicals) had on modern gender identification, sexuality, or masculinity/feminity definitions?

Posted: 28 Feb 2019 06:38 AM PST

Will future generations of humans experience swings in hormone-altering chemicals in their environment, causing eras of abnormally high/low levels of masculinity or femininity?

submitted by /u/phrogwing
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Does the amount you're sweating increase the rate and severity of sunburn, due to water refraction?

Posted: 27 Feb 2019 10:46 PM PST

Why does paralysis never seem to affect your heart? From diseases like MS, ALS and polio to neurotoxins like tetrodotoxin nothing seems to stop the heart only the diaphragm.

Posted: 28 Feb 2019 05:20 AM PST

How do plants, for example venus fly traps, "contract" by touch?

Posted: 28 Feb 2019 05:50 AM PST

They don't have nerves to pass on an electric signal, so what is the biology/chemistry behind it?

(English is not my native language so please excuse any mistakes or lack of clarity)

submitted by /u/Slumdogcindarella
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How does the body know when a fever is necessary?

Posted: 28 Feb 2019 07:29 AM PST

Is a fever a symptom of some sicknesses? Or is it more of my body's response to a disease? If it's my body's decision to create a fever, how does it know this is the best course of action?

submitted by /u/go-fireworks
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Is it possible to extract only the specific particles of any element present in air?

Posted: 28 Feb 2019 07:28 AM PST

not necessarily air, but say there's an environment and one wants to extract only hydrogen atoms/molecules/particles from it. Is it possible to do it. If not what are the reasons.?

submitted by /u/Playfair99999
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Is there a pressure at which we would no longer be able to identify differences between a liquid/solid?

Posted: 27 Feb 2019 10:59 PM PST

So I don't know too much about physics, but I read a little on Osmium, and changing states of matter under great pressure. Say we created an enormously deep pool of dense, but still very viscous liquid. Pressure increases viscosity at "low/med" levels, but, by theory, when getting to extreme levels, would the liquid ever reach a point where it became indistinguishable between a liquid/solid?
Let me know if this is a confusing question!! Happy to clarify things I did not answer with this post

submitted by /u/mygoats
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How do our ears know where sounds come from?

Posted: 27 Feb 2019 07:13 PM PST

All sounds enter our ear canal...how can the brain distinguish where it comes from when they all hit the ear drum?

submitted by /u/jmacker94
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Can you squish bacteria with your fingers?

Posted: 27 Feb 2019 11:30 AM PST

If a photon has momentum, wouldn't it appear to be going faster than the speed of light relative to the particle that emitted it?

Posted: 27 Feb 2019 10:34 PM PST

Would the particle be pushed back by the conservation of momentum? Wouldn't the particle be moving away from the photon, relative to the photon, at a speed slightly greater than c?

Google had no quick answer, sorry that I'm not great at physics

submitted by /u/capsjunior
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What can you do to protect yourself from radiation, and is it important?

Posted: 28 Feb 2019 03:21 AM PST

this includes natural, everyday radiation, but also people who go somewhere like chernobyl, what do they use for protection?

submitted by /u/BOT-JEFF
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How homogeneous is CO2 in the atmosphere? How much does this mixing (or lack of) impact climate change?

Posted: 27 Feb 2019 08:58 PM PST

I am trying to write an equation describing how much CO2 changes the temperature of the atmosphere as a function of concentration. I am trying to get it as accurate, but also as simple as possible.

Basically something one could fit in one lecture and on one white board...

If you assume CO2 is homogeneous, it makes this calculation much easier. But how different is it really? How much does it change based on altitude, and location (for example, above the middle of the ocean vs above the rain forest or the Sahara desert)?

I'm not an atmospheric scientist, but I would really like to understand the math for myself... Just so I feel better about backing up weather scientists.

Any insight or advice very appreciated.

submitted by /u/Virophile
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What would a very powerful electromagnet do to the human body?

Posted: 27 Feb 2019 03:51 PM PST

Is there weather on the moon?

Posted: 27 Feb 2019 06:19 PM PST

I know there is space weather, but are there any "weather" effects that only occur on the moon?

submitted by /u/DrVentureWasRight
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Is the Martian atmosphere too thin for a quadcopter drone to operate in conjunction with the rovers?

Posted: 27 Feb 2019 01:44 PM PST

Sorry if this is an incredible silly question.

Considering the fact that Martian gravity is also a lot lower than that of Earth, it could negate the atmospheric density, but the calculations for that are a bit out of my depth.

submitted by /u/emperorvinayak
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Relationship between diastolic blood pressure and arterial compliance?

Posted: 28 Feb 2019 03:06 AM PST

Why does a decrease in arterial compliance cause an increase in systolic blood pressure but a decrease in diastolic? To me it seems counterintuitive, wouldn't both be increased due to an increase in TPR?

submitted by /u/segawarfare
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If you are 1/6th your weight in water (on earth), are you also 1/6th your weight in water on Mars (or any other planet that has different gravitation)?

Posted: 27 Feb 2019 04:00 PM PST

Why do the chromosomes in the U. manicatus species of scorpion vary between individuals?

Posted: 27 Feb 2019 10:24 PM PST

Why are superbradyons superluminal?

Posted: 27 Feb 2019 09:57 PM PST

I'll start by saying I'm no physicist or even have a remote understanding of any of the maths.

I do know nothing can travel faster than light. I have a limited understanding of Lorentz contractions, and mass increase, as well as the causality and ANEC violations that come from any superluminal object. Thanks to reddit I now know why supersymmetry rules out tachyons, and I also understand that superbradyons are probably just theoretical, and just a mathematical construct.

But through all my searching, I just can't find why these particles can theoretically break the universal speed limit. From what I can gather they have such great energy that something happens to the surrounding spacetime (something about preonic space or something?), the vacuum energy drops, space is "emptier" than "empty" space, and c increases? Is this correct?

If not, then what exactly is it about superbradyons that allow them to violate this physical constant?

submitted by /u/AmrlKJaneway
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Wednesday, February 27, 2019

How large does building has to be so the curvature of the earth has to be considered in its design?

How large does building has to be so the curvature of the earth has to be considered in its design?


How large does building has to be so the curvature of the earth has to be considered in its design?

Posted: 27 Feb 2019 03:40 AM PST

I know that for small things like a house we can just consider the earth flat and it is all good. But how the curvature of the earth influences bigger things like stadiums, roads and so on?

submitted by /u/harryalerta
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Is elevation ever accounted for in calculations of the area of a country?

Posted: 26 Feb 2019 10:19 AM PST

I wonder if mountainous countries with big elevation changes, like Chile or Nepal for example, actually have a substantially bigger real area, or if even taking in account elevation doesn't change things much.

submitted by /u/green_pachi
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Does the method of drying hands (e.g. cloth towel, paper towel, hand dryer) affect the quantity of microbes left on the hands after washing?

Posted: 27 Feb 2019 12:06 AM PST

Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology

Posted: 27 Feb 2019 07:11 AM PST

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Economics, Political Science, Linguistics, Anthropology

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
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I've seen the charts for temperature rise, the scientific models predictions, the consensus statistics of scientific agreement on Climate Change. I believe it to be fact, but I do not actually understand WHY CO2, Methane, Water Vapor, etc.. cause this to occur. Can anyone explain *why*?

Posted: 27 Feb 2019 07:01 AM PST

I have done my fair share of trying my best to understand this issue, primarily to help explain to relative/friends/co-workers which are 'non-believers' but the truth is that I must not truly understand the issue either. I feel as though all of those skeptical also see "the charts for temperature rise, the scientific models for the future, and the consensus statistics of scientists agreement of climate change happening rapidly", but if you really think about it - none of those things give reasoning or logic as to WHY this is happening. They are just things that you see that show it is happening.

I had one co-worker give me the classic argument, "well yea that chart shows the temperature is rising but that doesn't mean CO2 is causing it."

Another statement I get when trying to explain, "The models the scientists have may agree, but you know how many assumptions we have to make for our models here [at work, engineering], imagine how many assumptions they have to input for the globes climate and atmosphere/ocean circulation.

WHY is climate change occuring due to CO2, Methane, Water vapor, etc...?? Do the molecules vibrate or hold vibration (temperature?) longer than simple air (O2, N2, etc etc)?? Is it because CO2 is more dense and therefore creates a denser environment which in turn holds the heat down on the surface easier?? Any insight is appreciated. I would like to be able to debate those without facts and actually be able to explain. If this takes further education/reading on my part, I'm not afraid to spend time learning.

I hope my question makes sense. Any responses like "It happens because CO2 causes warming" obviously don't understand why I'm asking. I'm asking why that exists. This is my plea for logical understanding. Thanks in advanced for your help.

submitted by /u/YoureProbablyRiiight
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Is human labor and delivery more dangerous than other primates'? Why?

Posted: 26 Feb 2019 07:06 PM PST

How do we know how many calories are in food or drinks?

Posted: 26 Feb 2019 08:44 PM PST

Why is superheated steam used in turbines since according to Gibbs‘ free energy formula, at higher temperature, the ability to produce work is lowered?

Posted: 26 Feb 2019 03:10 PM PST

So Gibbs' free energy is the maximum reversible work that can be produced in a thermodynamic system at constant P and T, and according to the formula, higher T means lower ΔG. Then why is Superheated steam used as means to produce work? Or am I looking at it wrong?

submitted by /u/lessavyfav68
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What is the exact difference between genotype and karyotype?

Posted: 26 Feb 2019 10:17 PM PST

When I say "genotype" I'm referring to the entirety of the chromosomal configuration or said differently, full genetic makeup of a human.... full, not just one aspect as I've seen used in some cases.

Given that we're using genotype in that context, what is the difference between genotype and karyotype?

submitted by /u/TheMythof_Feminism
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Why do gravitational lenses sometimes result in Einstein-crosses rather than full circles?

Posted: 26 Feb 2019 08:09 AM PST

In what way can the light be "bent" by a gravitational lense so that an observer sees two (or more) copies of the object rather than seeing a full circle? E.g. in Einstein-crosses you see 4 copies spaced evenly around the center. What about the spaces between those 4 copies? Why does the light not take these ways?

(Btw I asked this several times in different places now and never got an answer, sometimes I just got downvoted - I hope this sub is the right place)

submitted by /u/cptviolation
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how does red shift show that the big bang theory could be a possible theory, for the formation of the universe?

Posted: 26 Feb 2019 11:50 AM PST

Can solar panels run out of electrons?

Posted: 26 Feb 2019 01:50 PM PST

I understand that photons "bump" electrons, that the movement of electrons transform solar energy into electricity and that the electrons first come from the silicon in the solar panel, but do the electrons leave the solar panel since they are the current? If so, can a solar panel get its electrons back or is it doomed to die even if nothing else fails? If not, do the electrons stay in the solar panel somehow?

submitted by /u/AmIDumbOrWhatSerious
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What does ampicillin target?

Posted: 26 Feb 2019 09:37 PM PST

I know penicillin targets transpepidation, but how do the two differ? What makes one more effective than the other?

submitted by /u/__jerbear_
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If you placed a Foucault pendulum at the equator, would it fully rotate in one year?

Posted: 26 Feb 2019 04:45 PM PST

So I know the earth rotates under the pendulum, which majes the pendulum appear to rotate to us. What I wonder is if you put a pendulum at the equator and ran it for a year, would it fully rotate or nearly fully rotate over the course of the year? Although at the same time with this logic, it might seem that the foucault pendulum will have to become upside down instead of rotating. Does the pendulum do anything interesting?

submitted by /u/instantlightning2
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Can a pair of binary planets share an atmosphere without exceeding the Roche Limit?

Posted: 26 Feb 2019 05:19 AM PST

Can the distance between a pair of binary planets be close enough that the gasses making up their atmospheres could mix at the L1 Lagrange point, without either planet being pulled apart by their partner planet's gravitational field?

submitted by /u/Legendtamer47
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What state of matter is light?

Posted: 26 Feb 2019 09:51 PM PST

Wave particle duality says that light is a particle or a wave depending on how it is observed. It also introduces momentum and mass for light. If light is clearly matter, which state of matter is it in?

submitted by /u/sthornr
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Do caffeine and amphetamines like adderall affect the same parts of the brain?

Posted: 26 Feb 2019 07:52 AM PST

How to quantify political/diplomatic relationships between countries?

Posted: 26 Feb 2019 07:53 PM PST

Hi, I'm not sure if this is the best place to ask this.

I'm starting a project that will attempt to estimate the state of political relationships between countries through a set of data. The data set will comprise of certain keywords that indicate hostility, friendliness, etc. I was wondering if there was some equation or theory, paper, idea etc that could help me develop one. I'm searching for something similar to the Drake equation, or a comparable idea.

Any help would be greatly appreciated.

submitted by /u/Fuser55
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What portion of female cheetahs raise a cub to maturity?

Posted: 26 Feb 2019 07:51 PM PST