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Wednesday, September 9, 2020

What are we smelling when we open a fresh can of tennis balls?

What are we smelling when we open a fresh can of tennis balls?


What are we smelling when we open a fresh can of tennis balls?

Posted: 09 Sep 2020 12:08 AM PDT

AskScience AMA Series: I am an engineering professor who is currently studying how far a virus can travel and how 6 feet of social distancing may not always be enough to prevent host-to-host transmission. AMA!

Posted: 09 Sep 2020 04:00 AM PDT

Hi Reddit! I'm S. "Bala" Balachandar, a professor in the mechanical and aerospace engineering department at the University of Florida College of Engineering. Right now, I'm leading a study of aerosols and multiphase flow to determine how far droplets can travel and infect others. During the COVID-19 global pandemic, many safety guidelines currently set in place have been determined by outdated science that says we will be safe if we are six feet apart from a sick person.

I'm here to answer any questions you may have on the science behind virus travel, airborne transmission/host-to-host transmission, how inhalation and exhalation transmit a virus and the way particle sizes affect transmission.

At the University of Florida, my teaching interests are:

  • Computational fluid science
  • Large scale simulation of complex flows
  • Transition and turbulence
  • Multiphase flows
  • Environmental flows

More about me:

I joined the Wertheim College of Engineering at UF after teaching in the Department of Theoretical & Applied Mechanics at the University of Illinois, Urbana-Champaign from 1990 to 2005 and after I earned my Ph.D from Brown University in 1988. I am a fellow of the American Physical Society and the American Society of Engineers as well as co-editor-in-chief of the International Journal of Multiphase Flow and associate editor of the Theoretical and Computational Fluid Dynamics Journal. I am also the Principal Investigator at the Center for Compressible Multiphase Turbulence.

I'll be on at 2 PM ET (18 UT), AMA!

Username: /u/UFExplore

submitted by /u/AskScienceModerator
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Can energy be generated from very low temperatures instead of very high temperatures?

Posted: 09 Sep 2020 12:39 AM PDT

How does radiometrically dating rocks work if all radioactive isotopes came from super novae millions of years ago? Wouldn't all rocks have the same date?

Posted: 09 Sep 2020 04:49 AM PDT

How are the vaccine for animals different than for human?

Posted: 08 Sep 2020 04:23 PM PDT

For example, my coworkers had to take like 7 shots of rabies vaccine when she got bitten by a bat, but my cat gets a yearly dose. What factor changes from species?

submitted by /u/kiraxkage
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Is there a solution to the twin paradox not related to acceleration?

Posted: 08 Sep 2020 10:11 PM PDT

Most of the answers I have read from previous posts point to acceleration being the reason for the twins aging at different rates; however, it appears that acceleration is a common explanation because it is simple to understand but is a misconception. I am unable to wrap my mind around how the two frames are different if acceleration is not the driver for the difference.

submitted by /u/Hakotaco
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Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology

Posted: 09 Sep 2020 08:08 AM PDT

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!

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Why does a keg at 5 psi hiss when vented when atmospheric pressure is 14 psi?

Posted: 08 Sep 2020 06:59 PM PDT

I would think that the keg would only release pressure if it had a higher pressure then the outside environment, but I can vent a keg at 5 psi and hear it release CO2.

submitted by /u/randalls_gut
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Are there parts of outer space that would be loud or have constant noise?

Posted: 08 Sep 2020 07:58 PM PDT

How genetically different are the cultivars of Brassica oleracea? Can two plants of different varieties generate offspring?

Posted: 09 Sep 2020 05:04 AM PDT

Caves - Everywhere or in Select Places?

Posted: 08 Sep 2020 11:51 AM PDT

Its bugging me but I can't find a good answer to this; how widespread are caves and cave systems? Are they limited to certain rock types, geographic regions and physical conditions? Or are they everywhere? And if the latter then how far big of an area would I have to search or unearth to find one? And if the former then how often do these conditions occur?

I'm including caves that have and don't have an opening to the suface in this question by the way. I know this is a hard question to answer because so many places remain undocumented as to their cave status but I'm looking for best guesses and (reasonable) potentials.

submitted by /u/Olyfia
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How do doctors looking at CT Scans to find aneurysms account for things that are constantly changing, like artery size due to heartbeat? What about MRIs?

Posted: 08 Sep 2020 10:19 AM PDT

How does the heat affect snow in places with wildfires?

Posted: 08 Sep 2020 08:46 AM PDT

Alright, I was just reading a news post about the Colorado wildfires, and the apparent "early" snow they're receiving. In the news article it said that the snow would hit ground(I'm assuming it would accumulate), but that once it melted the fires would start back up.

So my question is: How does the snow that's so fragile make it to the ground to accumulate when the fires are burning at 1400+ degrees all around? Does the fire not affect the weather patterns around it?

Thanks!

submitted by /u/kamahele_
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How come retrovirus does not become dysfunctional after certain amount of mutations?

Posted: 08 Sep 2020 11:07 AM PDT

Retroviruses have high mutation rate due to the fact that reverse transcriptase doesn't have proofreading. The DNA get slight mutated after every time a virus infect a cell. If this happen long enough, eventually the DNA will get so mutated that it can no longer produce functional viral proteins. At this point, the virus will be no longer virulence, because its proteins are difference and may be not functional. What am I missing?

submitted by /u/IX0YE
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How does DNA recombination ensure the resulting chromatid is compatible?

Posted: 08 Sep 2020 11:33 AM PDT

During meiosis there's recombination between the two sister chromatids. This shuffles the genes to create a distinct chromatid. Let's say there are 4 genes each with 2 versions - a, A, b, B, c, C, d, D.

Recombination starts with a-b-c-d and A-B-C-D. The resulting chromatid is a-B-c-D. What happens if gene a is only compatible with gene d (not D)? That is, given a set of genes, only some combinations are compatible. What happens to the resulting gamete?

submitted by /u/SFTechFIRE
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What causes some proteins to denature at lower temperatures than other proteins?

Posted: 08 Sep 2020 02:33 PM PDT

I was listening to a Radiolab podcast today that was talking about fungi. In the podcast they talk about how fungi prefer temperatures around 86 °F and above that their proteins start to denature. What differences or factors make it so our human proteins can survive much higher temperatures than this?

submitted by /u/shiv6969
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Question concerning Gene molecular cloning?

Posted: 08 Sep 2020 07:04 AM PDT

Hi guys!

(So this is redirected from r/askBiology but I saw this community is way bigger, so maybe i'll get my answer faster here.

So my question is the following: So in DNA cloning we insert recombinant DNA (plasmid+gene of interest) in a bacteria, and once this bacteria replicates a lot to form a colony, the plasmid will also replicate with each bacterial division, giving us lots of recombinant DNA.

However my question is the following: In my slides it mentions that plasmids replicate independently from the bacteria's genomic DNA. So how can I be positive that for each bacteria division, I'll have my plasmid also having it's DNA divided? Is the cellular conditions for replication for the bacteria ALSO favorable for the plasmid? Or the plasmid just knows to divide itself when the bacteria divides itself.

submitted by /u/GodConcepts
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Tuesday, September 8, 2020

When someone has cancer they typically lose a lot of weight. Is this due to an inability to eat due to nausea or is there something about fighting cancer that is metabolically expensive?

When someone has cancer they typically lose a lot of weight. Is this due to an inability to eat due to nausea or is there something about fighting cancer that is metabolically expensive?


When someone has cancer they typically lose a lot of weight. Is this due to an inability to eat due to nausea or is there something about fighting cancer that is metabolically expensive?

Posted: 07 Sep 2020 08:01 AM PDT

How are the Covid19 vaccines progressing at the moment?

Posted: 08 Sep 2020 07:19 AM PDT

Have any/many failed and been dropped already? If so, was that due to side effects of lack of efficacy? How many are looking promising still? And what are the best estimates as to global public roll out?

submitted by /u/Curiosityitis
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Why do Catalan numbers show up in this square root expression?

Posted: 08 Sep 2020 03:14 AM PDT

A = R - sqrt(R2 - 1)

Where R = 5 * 10n (with a relatively big n)

e.g. when n=16, we find:

A=1.00000000000000000000000000000000010000000000000000000000000000000002000000000000000000000000000000000500000000000000000000000000000000140000000000000000000000000000000042000000000000000000000000000000013200000000000000000000000000000004290000000000000000000000000000001430000000000000000000000000000000486200000000000000000000000000000167960000000000000000000000000000058786000e-17

submitted by /u/BanX
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Does product placement actually work? Is seeing something for a few seconds in a show or movie enough to entice people to buy it even though they might not know anything else about it?

Posted: 08 Sep 2020 03:38 AM PDT

Would a quantum processor in theory be so much better at a brute-force attack on your password?

Posted: 08 Sep 2020 04:12 AM PDT

(Biochemistry) Why does a sucrose solution turn red during a Benedict's Test?

Posted: 07 Sep 2020 09:42 PM PDT

Okay, so I am looking for an explanation for why am getting a particular result between Benedict's Test and Sucrose.

According to many websites, sucrose is not a reducing sugar. However, I've done Benedict's Test multiple times in the past and the results are that a sucrose solution turns brick red.

So the Theory goes: Sucrose is a non-reducing sugar as its sucrose "aldehyde" group is participating in glycosidic linkage and the fructose "ketone" group is also participating in the linkage.

So why am I getting Red?

EDIT: Furthermore, the sucrose solution has not been heated in dilute acid as far as I know.

submitted by /u/Hikaritoyamino
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How do volcanoes with active magma chambers stay intact over time? Does the magma weaken or strengthen the structure of the volcano?

Posted: 07 Sep 2020 08:01 PM PDT

How close can an object orbit something?

Posted: 07 Sep 2020 10:19 AM PDT

Assuming the planet is a perfect sphere with no atmosphere. It would have to be orbiting faster and faster as you got closer to the surface right? So for say an earth sized object at what point would an object have to be travelling faster than light to maintain its orbit? An inch? A milimeter?

submitted by /u/ILurkTilIDont
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Hiroshima and Nagasaki nuclear bomb: why is it that leukemia was the most common type of cancer in the first years, but then after even decades other forms of solid cancer like breast cancer or colon cancer where more common?

Posted: 06 Sep 2020 09:03 PM PDT

I have been researching about the lasting effects of radiation and I am intrigued to know why is it that leukemia was the most common form of cancer just 2-5 years after the event, but then breast cancer appears soooo long afterwards. Aren't cells nuclei damaged since the moment of the event? What determines the latancy period in different types of cancer? Or is that dependent on the amount radiation?

submitted by /u/Germartel93
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Monday, September 7, 2020

How do we know what is in the core of the distant planets?

How do we know what is in the core of the distant planets?


How do we know what is in the core of the distant planets?

Posted: 06 Sep 2020 05:31 PM PDT

I tried to google for a bit and learned that we know what the inside of earth is made up by analyzing earthquake data (still not 100% sure how it works but I got the idea). But I could not find out how we know for example that the moon core is supposed to be liquid or even what further planets "contain" under their surface? Also how do we know what the temperatures inside the sun or other planets/stars cores are? Thanks a lot.

submitted by /u/Bamb00zld
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Is there an evolutionary advantage to Dolphins and Whales breathing air as opposed to developing gills and being able to remain underwater indefinitely?

Posted: 06 Sep 2020 10:05 AM PDT

Los Angeles saw temperatures above 120F (49C) today. How many years until they begin to see temps above 130F (54C)?

Posted: 06 Sep 2020 11:58 PM PDT

Alternatively: Did any models predict that LA could get so hot as what we're seeing now? What do those models tell us about the next decade?

submitted by /u/SmokeyBlazingwood20
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At what point is the phase III clinical trial of a vaccine considered complete? Is there a minimum time frame? Or some statistical threshold that is a function of duration and number of test subjects?

Posted: 06 Sep 2020 02:02 PM PDT

So, does the earth have seven or eight layers?

Posted: 06 Sep 2020 02:35 PM PDT

The core is composed of two layers, the mantle is in four layers, and the crust, so can we consider the crust one or two layers?

submitted by /u/habeuseenalienitsme
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If protons and neutrons both have a mass greater than 1 amu how can an atom with a mass number of N have a mass of less than N amu?

Posted: 06 Sep 2020 10:51 AM PDT

As an example according to my chemistry book Cl-35 has a mass of 34.97 amu.

submitted by /u/TheCyberParrot
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Do large earthquakes leave traces in the geologic record?

Posted: 06 Sep 2020 10:51 AM PDT

For example, if a magnitude 8 earthquake happened 30 million years ago, could we figure out that it happened and also when it happened by examining the geologic record?

submitted by /u/terryfrombronx
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Wing sweep angle and supersonic shock cone angle, is there an interesting interaction?

Posted: 06 Sep 2020 08:55 PM PDT

Per my understanding, aircraft will often have swept wings to reduce drag. Something about cord-wise drag vs spanwise drag, not entirely sure.

Supersonic objects will create a sonic boom, the angle of which depends on the speed, right? Higher Mach speeds producing a sharper angle.

My question then, is thus: What's the relation between the sweep angle of the wing (or more generally, the pointiness of a projectile) and the Mach number? Do we see any interesting occur when the mach cone is smaller than the object angle? What about crossing that threshold?

submitted by /u/ThePerpetual
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Could we tell a message is maximily encrypted from random?

Posted: 06 Sep 2020 05:35 AM PDT

If a cell's telomeres are maintained by the hormone telomerase, will that cell be able to divide indefinately. If so, will the cell be considered Immortal?

Posted: 06 Sep 2020 06:50 AM PDT

How is hydrocortisone manufactured for medical use?

Posted: 06 Sep 2020 08:19 AM PDT

What gives lightning its color?

Posted: 06 Sep 2020 08:06 AM PDT

What gives lightning its color? I know that lightning bolts are essentially plasma. So does it have to do with the argon concentration in the atmosphere? Thanks :)

submitted by /u/Outliver
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Do pelvic splanchnic nerves provide both parasympathetic and sympathetic innervation to the hindgut?

Posted: 06 Sep 2020 08:55 AM PDT

I was looking through a textbook that said the splanchnic nerves provide sympathetic innervation to the hindgut, but I remember learning last year that they were part of the parasympathetic system (because it's sacral outflow). I've looked for answers online and pretty much just see that they're parasympathetic, so I'm not sure if the textbook is wrong or if I'm not looking at the right sources online.

submitted by /u/mybustlinghedgerow
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What is a clonal genotype and how is it different from the parental genotype?

Posted: 06 Sep 2020 08:45 AM PDT

I've run across this term recently and I'm perhaps limited by my knowledge of cloning. I thought a clone was genetically identical to the parent so how could the genotype be different?

submitted by /u/orangeElysia
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Why does our body not store zinc?

Posted: 05 Sep 2020 11:24 PM PDT

I know that zinc is important for our body and we need daily dose of it but why isn't it stored in body for later use?

submitted by /u/Zatch_1999
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Does the human body heal wounds at a constant rate 24/7 assuming energy needs were met?

Posted: 05 Sep 2020 07:23 PM PDT

How does Alzheimer’s kill you?

Posted: 05 Sep 2020 07:47 PM PDT

Sunday, September 6, 2020

Sometimes when we rub our eyes too hard you lose your vision for a second and then it comes back gradually. Why is that?

Sometimes when we rub our eyes too hard you lose your vision for a second and then it comes back gradually. Why is that?


Sometimes when we rub our eyes too hard you lose your vision for a second and then it comes back gradually. Why is that?

Posted: 05 Sep 2020 10:42 PM PDT

Quick question, how does a rocket engine like Merlin 1D NOT melt the rocket's nozzle?

Posted: 05 Sep 2020 10:58 AM PDT

What kind of material withstands so much heat and energy from that kind of rocket engine? How can they be reusable? I saw a testing video from SpaceX that lasted 3 mins and couldn't stop wondering how is it that the nozzle of the engine didn't melt away.

submitted by /u/TraceHunter69
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Why do many various neurotransmitters exist if nerve signals are binary?

Posted: 05 Sep 2020 10:22 PM PDT

As far as I know neurotransmitters are only released, bound to receptors and reuptaken in the synpatic cleft. I that is the case, then what's the point of multiple neurotransmitter types if chemical signal is going to only be translated into a binary electric signal that is 1 (excitation of the membrane), while none is 0 (resting membrane potential)? For me, in my limited knowledge, it appears as if their existance is useless since electrical signals alone or just a single neutrotransmitter type would suffice, unless neurotransmitters were released into the intracellural space and all neurons in an area of the brain with specific receptors would pick them up, which isn't a case in models I can find on the internet or in books.

I know I am wrong but having asked many highschool teachers noone was able to answer this question to me years ago. Can anyone explain this to me in best detail possible?

submitted by /u/dreamingcel
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If the lungs in land vertebrates evolved from the gas bladder, what did the gills evolve into?

Posted: 05 Sep 2020 04:28 PM PDT

How do modern ship anchors work? If they get stuck on the sea bed how do we free them?

Posted: 05 Sep 2020 03:16 PM PDT

How do modern sea anchors work? Do they hook onto rocks? Sink into the sea bed? Just weight the ship down? What happens if they get stuck?

submitted by /u/Sllinder
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Why diseases like hepatitis, measles still exist even there is the vaccine?

Posted: 05 Sep 2020 09:32 AM PDT

The smallpox vaccine was developed by Edward Jenner, in 1796. After many years, WHO issued its official declaration that 'the world and all its peoples have won freedom from smallpox' in May 1980. We also have vaccines against some viruses and bacterias. Why cannot we eliminate them?

submitted by /u/ernstwmayr
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Does the human body absorb Vitamin D from the sun via the eyes or skin?

Posted: 04 Sep 2020 03:22 PM PDT

Keep finding conflicting answers on this online

Can you absorb vitamin D from sun fully clothed head to toe but keeping your eyes open on a sunny day (absorbed through eyes)

Conversely, could you absorb vitamin D from the sun while laying out tanning but with your eyes closed (absorbed through skin)

I always thought it was the latter but I was recently told otherwise and I haven't been able to find a consistent answer online

submitted by /u/MulhollandDrive
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