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Tuesday, July 30, 2019

How did the planetary cool-down of Mars make it lose its magnetic field?

How did the planetary cool-down of Mars make it lose its magnetic field?

How did the planetary cool-down of Mars make it lose its magnetic field?

Posted: 30 Jul 2019 02:41 AM PDT

Do earthworms in a small-scale closed vermicompost system (a home worm-box) show physiological or behavioural adaptations to the specific types of waste added to the system?

Posted: 30 Jul 2019 01:12 AM PDT

For example: a system where at least 20% of all incoming waste is coffee grounds, vs a system that gets none of that.

Let's assume the timescale we're talking about is 10 to 15 years. That would be (?) ~100 generations of worms.

submitted by /u/Bastionna
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What are Planck units (mostly Planck time, but also the others) actually used for?

Posted: 29 Jul 2019 11:11 PM PDT

I read somewhere that there were more Planck time units in one second than there were seconds that had elapsed since the beginning of the universe. Whether that statistic is actually true or not, what could possibly happen so quickly that a unit of time that short is needed to measure it? And, if I understand correctly, the other Planck units are also extremely small. What are they actually used for as well?

submitted by /u/bcmatt25_
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Does being exposed to confrontation/danger on a daily basis naturally increase testosterone levels?

Posted: 30 Jul 2019 02:13 AM PDT

Is the universe quantized or continuous?

Posted: 30 Jul 2019 02:26 AM PDT

Perhaps with the exception of energy levels. Is there a shortest lenght, time etc implied by plank units or are they just useful scaling factors?

submitted by /u/squiryl
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How do doctors determine if a tumor is benign or malignant?

Posted: 29 Jul 2019 10:50 PM PDT

How long does water spend in the human body?

Posted: 29 Jul 2019 01:10 PM PDT

Is there a half-life to it? Given that some will pass right through, but (most?) will be absorbed into the bloodstream etc., there must not be a single answer, but all I can find online is short term answers talking about when that which passes through quickly will leave. What about the water that's more thoroughly absorbed, like that in bone marrow?

submitted by /u/TheLateAvenger
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Can you tell the date and your location from the stars?

Posted: 29 Jul 2019 12:49 PM PDT

Hi, I'm writing a story where the characters wake up and they don't know where they are and don't know how much time has passed. Since many of them are experienced sailors, one decides to use the stars to figure out where they are, and it turns out that it's the Atlantic ocean and 150 years in the future. Is that the kind of thing that's possible, and if it is, how accurate/precise would it be?

submitted by /u/gmrm4n
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How are the calories in food calculated?

Posted: 29 Jul 2019 03:40 PM PDT

Do climate models account for water being removed/added by growth and/or decomposition of total global organic materials? What is the magnitude of this effect compared to other factors affecting sea levels such as the water cycle and global ice loss?

Posted: 29 Jul 2019 08:38 PM PDT

Typical examples of the Carbon cycle follow the process of organic matter growth/burial and decay with respect to CO2. I'd like to find out what impact the hydrogen in this organic matter has on global H2O and sea levels. Additionally how does this compare to other sea level variables?

submitted by /u/Tnediluc
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What is this chemical structure that was spray-painted onto this van?

Posted: 29 Jul 2019 09:36 AM PDT

The chemical structure in question is on this photo.

https://imgur.com/a/OgljeW6

I pass by it a few times and wondered what could possibly be so important, it was spray-painted onto the side of the person's van.

I've done google search and found nothing exactly like it.

I've asked chemistry and chemically-inclined friends, all to no avail.

submitted by /u/cooleyandy
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Why can't we use the sine relation to pi to find the digits of pi instead of all the diverging series?

Posted: 29 Jul 2019 08:56 AM PDT

*converging, made a mistake.

submitted by /u/spaceraygun
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If we had a Coelacanth from 65 million years ago, could it mate with a modern day Coelacanth of the opposite sex?

Posted: 29 Jul 2019 02:52 AM PDT

Coelacanth are said to be living fossils, but as I understand, the mark of a species is to be able to produce fertile offspring, if the Coelacanths from 65 million years ago are indeed the same species as today they should be able to procreate, otherwise they would just be 2 closely related species that look very similar, right?.

submitted by /u/Frigorifico
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Why are rare earth metals good luminescence activators?

Posted: 29 Jul 2019 11:30 AM PDT
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Monday, July 29, 2019

Are micro black holes even dangerous?

Are micro black holes even dangerous?

Are micro black holes even dangerous?

Posted: 29 Jul 2019 03:33 AM PDT

I don't know if I got this right, but as I understand it black holes interact only through gravity, so if there was a black hole with a mass of the Earth, the Moon wouldn't fall in it, cause gravitation will remain the same. If that's true - what was fear with micro black holes in CERN all about. I know that there was a really low possibility, but hypothetically are micro black holes even dangerous?

submitted by /u/stopr52
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When plotting exoplanet discoveries with x being semi-major axis and y being planet mass, they form three distinct groups. Why is this?

Posted: 28 Jul 2019 08:47 AM PDT

I created the following plot when I was messing about with the exoplanet data from exoplanets.org. It seems to me to form three distinct groups of data. Why are there gaps between the groups in which we don't seem to have found many exoplanets? Is this due to the instruments used or discovery techniques or are we focussing on finding those with a specific mass and semi major axis?

submitted by /u/djbog
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Do animals regard machines as other animals and try to bite them, eat them, etc? At what point do they/can they distinguish machines from animals?

Posted: 28 Jul 2019 09:07 PM PDT

I've always wondered if a snake would try to bite a drone that landed near it. If it did, would it try to bite a lawnmower? A CAR? At what point do animals distinguish living things from machines? Has this ever been studied?

submitted by /u/Shakedaddy4x
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Can someone just give me a non-doomsday summary of what we can realistically expect from climate change and how our lives will be impacted over the next 100 years in different regions?

Posted: 29 Jul 2019 02:24 AM PDT

What is happening when our brain is "waking up"?

Posted: 29 Jul 2019 07:52 AM PDT

Do certain processes "boot" later than others? How does the brain prioritize which systems come online first? Why aren't we firing on all cylinders right when we wake up, sometimes taking up to an hour before we're fully cognizant for the day?

submitted by /u/ex1stence
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How are the North and South poles determined for a black hole?

Posted: 29 Jul 2019 08:36 AM PDT

I was watching a BBC show on black holes and they mentioned that (Hawking) radiation escapes through the North and South poles. My question is, how do scientists determine which pole is North and which is South? And what is the importance to determining which pole is which? Does something different occur at the North vs. South poles of a black hole?

submitted by /u/DNAhelicase
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Do individual winged insects (say dragonflies) of the same species have matching vasculature in their wings?

Posted: 29 Jul 2019 05:19 AM PDT

Does getting in shape before having a kid change the child’s genetics/shape?

Posted: 28 Jul 2019 08:41 PM PDT

Let's say I wanted to have kids with somebody in 6 months.

If I hit the gym hard, built my stamina and lean muscle mass a lot during the 6 months, would my child be more likely to be in shape than if I hadn't done that?

What about other factors like tanning, would their skin be more tan if I were tan?

If the answer is yes you can impact them with these changes, what all changes can you make that might impact them?

submitted by /u/12thman-Stone
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Is sugar itself harmful, or is it just considered to be harmful because people overeat and/or replace important nutritional food with sugar?

Posted: 29 Jul 2019 05:51 AM PDT

Are their any risks to life expectancy for patients who receive donor organs that are older than their age?

Posted: 29 Jul 2019 05:46 AM PDT

So I have a question.

Does putting an older person's organs in a younger patient have any risks?

Like, would someone who was say 12 years old have the same average life expectancy if they were to have the heart of someone who gave their organ at say 35 years old+?

submitted by /u/cmcbert
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When people are asleep and you lift up their eyelids,why dont they see what their eyes are seeing?

Posted: 29 Jul 2019 05:15 AM PDT

What actually is a gut feeling? Is it a legitimate kind of natural “defense mechanism” or is it really all in our head (or gut)?

Posted: 29 Jul 2019 04:32 AM PDT

What's the difference between an emulsifier, a solubilizer, and a surfactant?

Posted: 28 Jul 2019 08:55 PM PDT

When I look it up, it all sounds like the same thing and it's confusing me.

submitted by /u/BurninFern
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At what age do children begin to learn by classical conditioning?

Posted: 28 Jul 2019 04:43 PM PDT

References appreciated! Settling a discussion between friends (both non-parents)

Information on the long term consequences of different types/severity of punishment also appreciated. (I.e. what are the long term consequences of mild physical punishment as a deterrent? Do all degrees of physical punishment carry negative effects?)

submitted by /u/hokye
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Has the mass infrastructure of light on earth affected our brightness in space? Are we more visible from farther away?

Posted: 29 Jul 2019 12:09 AM PDT

The thought crosses my mind when I see pictures of big cities or even entire countries from space. I understand that those satellites are relatively very close to earth, but have all the lights on earth increased our planets brightness in space?

submitted by /u/TheTubbyTapir
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Do spotted/striped animals change their patterns over time or in response to their environment?

Posted: 28 Jul 2019 07:42 PM PDT

Do animals like leopards, zebras, giraffes, tigers, etc. change their stripes or spots in response to their environment over the course of their life? Do these stripe or spot patterns change naturally as the animal gets older or are they fixed from birth?

submitted by /u/_HeadsorTails_
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What causes a progression of symptoms? Ie. When I get sick why don't I have all the symptoms I would experience from the start, until I'm better.

Posted: 28 Jul 2019 11:25 PM PDT

Did the recurrent laryngeal nerve evolve much later as compared to the superior laryngeal nerve in animals?

Posted: 28 Jul 2019 10:51 PM PDT

In human beings (I'm assuming it's similar to other mammals), the recurrent laryngeal nerve which is the nerve supplying the laryngeal muscles (except cricothyroid) branches off the vagus at the level of the subclavian artery, and the loops around it and comes back up to supply the laryngeal muscles.

The superior laryngeal nerve and it's branches the internal and external laryngeal nerves branch off at much higher, close the level of the hyoid bone.

Proposing a hypothesis: In ancient animals, they only had an external and internal laryngeal nerve (branches of superior laryngeal nerve) which was somehow modified and provided functions of normal sound production/opening larynx for breathing.

The recurrent laryngeal nerve evolved much later in primates which allowed them greater modulation over the laryngeal muscles allowing them to speak.

Does anyone have any evidence to back this up? Or is there any reason for the weird course of the recurrent laryngeal nerve?

submitted by /u/HouhoinKyoma
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How do (we think) type-II semiconductors work?

Posted: 28 Jul 2019 10:40 PM PDT

Does caffeine affect people with different body weight differently?

Posted: 28 Jul 2019 01:56 PM PDT

What is the physics behind ice hair growth and could we use the principles to grow something useful?

Posted: 28 Jul 2019 07:20 AM PDT

carbon nanotubes for example

submitted by /u/imaginary_name
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Astronomy: Find the distance to Pluto from Earth?

Posted: 28 Jul 2019 01:38 AM PDT

I was wondering if i could calculate the distance to Pluto using only the right ascension of Pluto from earth from two different days and the speed of earth to be able to obtain the difference and utilize that for the parallax and geometry to find the distance from the earth to Pluto. I've tried multiple different ways but i don't seem to understand from where to start the right ascension. I found out that it starts from the vernal equinox but i am still extremely confused. I hope you can help me.

Thank you

submitted by /u/yannicleupin
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Sunday, July 28, 2019

Can electricity arc in a vacuum?

Can electricity arc in a vacuum?

Can electricity arc in a vacuum?

Posted: 27 Jul 2019 01:09 PM PDT

How is dirt/debris/inorganic material handled or processed when a caterpillar passes through the pupal stage (and digests itself)?

Posted: 27 Jul 2019 12:36 PM PDT

Where I live (rural area) there are always lots of caterpillars seen near the fields and crossing roads this time of year. It is hot and the roads are oily and lots of tar/rock chip, etc. There have to be oil / tar / debris that sticks to the hairs of the caterpillars, and I was wondering how this stuff is accounted for when the caterpillar turns itself into soup inside the chrysalis. Do they shed an outer layer or dispatch of the hairs/fur before going through this process, to avoid complications? Could certain debris or chemicals cause issues during this transitional phase?

submitted by /u/vonKemper
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Can a person with high blood pressure donates blood?

Posted: 28 Jul 2019 08:02 AM PDT

Let's say his/her blood pressure was high but still donates blood anyway. What would happen to him/her?

submitted by /u/bernamadanial
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Why do conventional spin echo MRI do not seems to have problem of signal saturation like gradient echo with large flip angle?

Posted: 27 Jul 2019 09:00 PM PDT

Hello, I am a radiographer and was taking a course in MRI medical imaging.

According to the lecturer, the gradient echo sequence was designed to have a short repetition time (TR) to reduce scan time. However, with short TR, there will be signal saturation for each scan cycle due to the low recovery of longitudinal magnetization after each scan cycle. The solution is to use a small flip angle to compensate for the signal saturation.

Then, there is a problem that confused me. If what he said was true, then when we do a conventional spin-echo sequence (use 180 degrees RF pulse for echo). Why the signal saturation is not a problem? I asked this question to my lecturer. He answered that "that's why we should not use too short TR even in conventional spin-echo sequence"

I thought of an example.

By definition, T1 relaxation time is the time required for the z-component of M to reach (1 − 1/e) or about 63% of its maximum value (Mo).

Let's say I want to do a T1 weighted scan for a muscle with a typical TR time of 800msec. The T1 relaxation time of a muscle is around 900msec.

According to the T1 relaxation equation. after each cycle, the longitudinal magnetization will be recovered to 58.9% of its original value. According to this calculation, then, after 10cycle, there will be only 0.5% of magnetization remains? If using 256 phase encoding level. There should be no signal left at the end of the scan?

I know there must be a mistake in my thinking. Because it contradicts the real life situation. What mistake did I make here?

submitted by /u/CXR_AXR
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How many years ago did insects emerge?

Posted: 27 Jul 2019 12:26 PM PDT

Since insects has no bones and fossils, does anybody know which age probably did insects emerge?

submitted by /u/crapheap
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How does the collapse of a magnetic field cause a voltage spike?

Posted: 27 Jul 2019 12:47 PM PDT

In ignition coils in the automotive world, a large surge of voltage is needed to jump the air gap of a spark plug. the primary coil receives 12 vols and generates a magnetic field, that field directly effects the secondary coil in this case to step up the voltage, and i feel like i understand that much. My question is what is special about the collapse that allows for a surge large enough to jump the air gap, or is it simply because the stored voltage in the secondary coil is finding the quickest path to ground. i am also not sure which flair is best here...

submitted by /u/Mccreesuschrist
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If cells are often dying and being replaced (I often here you have an “entirely new body” every seven years) then why does damage from youth (alcohol, drugs, sun exposure) lead to health problems later in life?

Posted: 27 Jul 2019 06:06 AM PDT

How widespread (or not) are songbird languages?

Posted: 27 Jul 2019 05:33 AM PDT

Can different species understand each other? If so, can introduced species communicate with native ones?

I've asked this before, but that category didn't work out. Google only gets me stuff about birds speaking English. Is this something no one knows?

submitted by /u/tracishea
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Why did/do video and computer games need save points?

Posted: 27 Jul 2019 11:57 AM PDT

Playing a rerelease of an old game, and it struck me how strange it is to have to go to a specific save point to save my game data. Some modern games also have this feature, though most (in my experience) autosave or let you save whenever, so I assume this is just for nostalgia/familiarity in these games rather than by necessity.

Could anyone explain why save points like that were necessary? What's going on behind the scenes that makes that location be the only one saving data can occur?

submitted by /u/arh1387
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Why do Acids Melt Stuff?

Posted: 27 Jul 2019 02:14 AM PDT

Obviously, they don't annihilate the very atoms of a substance they come into contact with, but why do acids actually melt stuff?

submitted by /u/LjSpike
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How did humans of the past deal with wisdom teeth? Did they remove them without anaesthetics or did some people just suffer in pain?

Posted: 26 Jul 2019 10:14 PM PDT

How do our brains conceptualize math at the neurological level? Do our neurons seem to act like little Turing machines? Or do they operate on some other model?

Posted: 26 Jul 2019 07:46 PM PDT

Is acne as common on lesser primates as it is on humans?

Posted: 27 Jul 2019 12:53 AM PDT

Where is the asteroid that creates extinction for dinosaurs?

Posted: 27 Jul 2019 03:18 AM PDT

What changes the color of electricity?

Posted: 27 Jul 2019 02:11 AM PDT

I've seen footage of lightning striking ground, and the flashes are often a pale orange.

As an industrial battery technician, I've seen plenty of arcs and they are almost always blue.

Lightning in the clouds looks white.

I've seen high voltage line arcs that are bright turquoise. Which is the same color as the corrosion produced by sulfuric acid on copper.

Arc flashes are often yellow.

submitted by /u/Halorym
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What is happening within my body/pores when I pop a pimple and it returns later? *resubmitted

Posted: 26 Jul 2019 11:32 PM PDT

I'm curious about what exactly goes on in this situation; especially since the time gap between the initial pop and the return of the whitehead can range (anecdotally) from an hour to a day, and sometimes returns more than once in the same day.

submitted by /u/nina_qj
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When they say that epithelium/parenchyma is the functional part of cells, what precisely do they mean by functional?

Posted: 27 Jul 2019 02:50 AM PDT

The epithelium covers outer organ and inner part of cavities, but what about that is functional?

submitted by /u/Firm_Salamander
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When in tense or scary situations, why does the heart beat faster? Does increased blood flow make you more alert or capable?

Posted: 26 Jul 2019 08:21 PM PDT

The hormone adrenaline causes the increase in heart rate, but why?

submitted by /u/Professor155
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