I have read that we feel sleepy when our brain doesn't get oxygen.

Research is a little mixed, but it looks like the brain specifically doesn't get less oxygen during digestion. Your brain does coordinate signals telling you to slow down though.

This tradition screwed heavily with me when I started working on industrial electrical equipment. Green means safe (off) and red means danger (energized). More common in Europe, but since the main mfg of equipment I was familiar with was an international company, we had to be well familiar with both options.

Nothing is actually deleted. The computer just removes the file path and the information gets overwritten. There is recovery software that can help recover lost files that have been accidently deleted. If you really want to erase something, run a program called BC Wipe which will overwrite files 5x to make sure they are thoroughly gone.

I'm colorblind and the green doesn't even look green to me. It's more like white to my eyes.

Years ago I read somewhere that green lights have a fair amount of blue mixed in to give the colorblind a better chance of distinguishing them. Anyway, full colorblindness, as in only seeing in black and white, is very rare. Most colorblind people can function just fine.

BTW, doctors almost never use X-ray machines themselves, except some Cardiologists and Radiologists. It's almost always Radiologic Technologists doing the imaging.

The answer is that not all x-rays are created equal, and, not all RAYS are created equal. They have energies that vary widely. Microwaves, visible light, radio waves, UVA and UVB waves, x-rays, Gamma rays, etc. are all parts of the "electromagnetic spectrum" AND different types of these rays interact with matter differently. For instance, you can focus light through a magnifying glass, but not X-rays.

The issue here is that the airport scanners DO use a form of "radiation", but, not knowing how else to describe them, people say, "sort of like X-rays".

The scanners scanning the bags on trays use X-rays, and have protective shields. The body use a very specific energy of 30-300 GHz, capable of penetrating just a TINY thickness of matter before almost all essentially bounce off, though a few are absorbed on the very surface of the skin (just like heat and light can be) where the skin cells are already dead and can't be harmed. The imager counts on the ability of these mm-waves to get through most clothing, but then bounce off.

The one thing that is a good idea is closing your eyes, because the mm-waves won't penetrate your eyelids, but the very surface of your open eyeball is less protected.

And now for the missing info. The green is not green, it is a green/blue mix. This is so color blind people can see the difference, especially when driving in the dark (which all of the "green is at the top" people are ignoring - if you are driving at night and can only see the single light, the red and bluey green are still different)

If the main purpose of guns is self defense, why do we need regulations and rules regarding them?

Because not everyone is in desperate need of one or will use them responsibly.

If we gave out guns to anyone who wanted one society would crumble.

Epi-pens are of course not as lethal as guns but if you use one and don't need it you're going to damage yourself. Adrenaline is great if you need to outrun an assailant or wild animal or need your heart to start beating but too much of it will damage your heart and muscles.

When they talk about Mothers lifting cars off their children in an Adrenaline rush those mothers often also end up needing medical attention because they tore their muscles to shreds lifting that car, not noticing because Adrenaline can turn off your pain receptors.

People who are/were "Adrenaline junkies" doing high intensity sports or stunts tend to have a larger chance of heart issues because they're overworking their hearts everytime they get their high meaning they go bad earlier.

Exactly. If you ever get rid of a computer, it's worth spending the money on a program that will right over the files methodically with null files. Alternatively, just encrypt your device when you first set it up and you should be fine (though encryption could be broken at some point in the future).

I had heard it was short for an English phrase "constable on patrol "

There isn't really any such thing as "deleting" memory so that it becomes "empty". Individual memory locations can either be a 0 or a 1 at all times, there are no other options. You could write all zeros into the memory but that's still data. There is no way to "clear" a memory location such that it's neither a 0 nor a 1. That's why it's most efficient to delete a file by just freeing up those memory locations but not actually overwriting them, unless you're concerned about Russian spies getting your hard drive and restoring deleted data.

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Tradition. Red is the most easily/quickly recognized color, so it was assigned as "Stop". Green is opposite red on the color wheel, so it was assigned "Go". Yellow is in between those two and is also highly recognized, so it was assigned "caution - changing to stop soon".

Colorblind people CAN drive.

First off, there are different types of color-blindness, and not all of those interfere with interpreting the signals.

Also, stoplights are standardized so red is at the top & green is on the bottom. For horizontal lights, red is always on the left and green is always on the right.

The colors were chosen for their ability to stand out from natural background lighting and for the general human ability to see them. (Red and Yellow are naturally easy for the human eye to see).

Finally a colorblind person wouldn't be impacted since the they can just count the lights. The top light is "stop" and the bottom is "go" regardless of color.

Tradition. There are better colors possible, but now these ones are the ones everyone is used to and there's no way it would be possible to change all the lights at once, and it would cause a lot of accidents to have only some changed.

Colorblind people can drive. Even if they can't distinguish the colors, the order of the lights is consistent and can be used to determine which light it is.

Thanks for your answer!

I know, and OP got this answer already. I was just saying that the previous commenter was misunderstanding the original question.

Mostly useless remark, quoting you,

> People often ask why deleting files is faster than creating files

That's the case for the most common operating systems. However, sometimes, with server hardware + software, it's working differently and deletion can take a long time, as with linux's ext4. It's still relatively fast, but much slower than the others nonetheless.

Xray don't penetrate metal all that well.

In the hospital, they are shining an x-ray into you in an open space, not exactly contained, so medical workers need to shield themselves.

But at the airport, the xray is surrounded in a metallic box, effectively surrounded by shielding.

> this effect is actually seen in our gps satellites. time goes slightly different for them

There's a specific orbital height where the slow down in time from traveling at orbital velocity and the speed up in time from leaving the local gravity well exactly cancel each other out so you experience time at the same rate as someone standing on the surface.

It's just above 3000 km for Earth. So GPS goes slower faster due to their speed height.

There is three ways:

• computer says "I don't if this sector of memory would get rewritten". Most of the data restoring software works by ignoring it

• computer will rewrite fill memory sectors with zero. Data is 0s and 1s that have meaning, if everything is 0s, there would be no meaning.

• physical way - do something with hardware to erase data

https://en.m.wikipedia.org/wiki/List_of_police-related_slang_terms

Here’s a detailed summary of all the usual nicknames for the police, across cultures

People often ask why deleting files is faster than creating files. The answer is because the bulk of the file's data is NOT erased, because that's considered wasted effort. When the new file comes along it will write over the data, completely unaware of what was once there. So actually blanking out the old data doesn't really accomplish anything and the "delete" is really fast by just dealing with the file listing paperwork.

...unless there's privacy concerns that warrant actually clearing the data, specifically because preventing undelete from being possible is the goal. This is sometimes called "secure delete". But if you're uninstalling a video game, who cares?