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Why Do I Sometimes Scratch One Body Part and Feel It on Another?

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Ever scratch an itch on your stomach and feel the scratch on your elbow? Or scratch your leg and feel a prickly sensation on your neck? You’re not alone. Lots of people report feeling a sensation from a scratch in places far from where they’re scratching, including scratches on the ear that produce tickles in the throat and mixed signals between their thumb and their tongue. 

It’s one of those delightfully weird things your body does, and it’s been studied, albeit infrequently, for hundreds of years. English clergyman/scientist Stephen Hales first described the phenomenon in the 1730s, referring to it as “instances of the sympathy of the nerves.” About a century later, physiologist Johannes Muller came along and applied one of those cool words to it that the Germans are really good at coming up with: mitempfindungen. Since then, we’ve just called it “referred itch” in English. 

For most people, referred itch is just a weird annoyance. It doesn’t do any damage or have any ill effects, and so it doesn’t get a whole lot of research attention. Scientists haven’t even been able to nail down how common it is. One study found that it only happens in 10 percent of the population. Another said 20 percent. Still others put the figure at anywhere between half and ninety percent of people. 

How and why it happens is anybody’s guess, but scientists have a handful of hypotheses to explain what’s going on. One idea is that referred itch is the product of our complex system of nerves being “rather irregularly distributed” throughout the body. British physician Phillip Evans wrote in the 1970s that it was difficult for him to envision “such a diffuse system providing sensations that are so clearly imagined to be in small and easily localised areas of skin.” In other words, in our haphazard map of nerves, some sensations are bound to be confused. 

Another explanation in a similar vein is that some branches of a nerve may travel out in a much different path than the others and wind up in some far-flung part of the body. Again, the nervous system gets a little confused and a “stimulus at the end of one branch is interpreted as coming from a point of ending of the other.”  

It could also be that the mix up isn’t in the nerves, but the brain. In the parts of the brain that deal with our sense of touch, regions that receive and process information from different parts of the body overlap. “Hand and shoulder areas … overlap the trunk area, and the area for the thumb overlaps that for the upper part of the tongue,” Evans wrote. “There is so much overlapping that it is difficult to see how referred itches arising from different parts of the body can be coherently separated in the cortex.” 

Finally, for some people, chronic referred itches could happen in parts of the body “rendered abnormal by damage to the nervous system.”

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Why Are Mugshots Made Public Before a Suspect is Convicted by the Court?
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Jennifer Ellis:

Several reasons.

1. Mugshots can help find people when they have absconded, or warn people when someone is out and dangerous. So there is a good reason to share some mugshots.

2. Our legal system requires openness as per the federal constitution, and I imagine most if not all state constitutions. As such, this sort of information is not considered private and can be shared. Any effort to keep mugshots private would result in lawsuits by the press and lay people. This would be under the First and Sixth Amendments as well as the various Freedom of Information Acts. However, in 2016 a federal court ruled [PDF] that federal mugshots are no longer routinely available under the federal FOIA.

This is partially in recognition of the damage that mugshots can do online. In its opinion, the court noted that “[a] disclosed booking photo casts a long, damaging shadow over the depicted individual.” The court specifically mentions websites that put mugshots online, in its analysis. “In fact, mugshot websites collect and display booking photos from decades-old arrests: BustedMugshots and JustMugshots, to name a couple.” Some states have passed or are looking to pass laws to prevent release of mugshots prior to conviction. New Jersey is one example.

a) As the federal court recognizes, and as we all know, the reality is that if your picture in a mugshot is out there, regardless of whether you were convicted, it can have an unfortunate impact on your life. In the old days, this wasn’t too much of a problem because it really wasn’t easy to find mugshots. Now, with companies allegedly seeking to extort people into paying to get their images off the web, it has become a serious problem. Those companies may get in trouble if it can be proved that they are working in concert, getting paid to take the picture off one site and then putting it on another. But that is rare. In most cases, the picture is just public data to which there is no right of privacy under the law.

b) The underlying purpose of publicity is to avoid the government charging people and abusing the authority to do so. It was believed that the publicity would help protect people. And it does when you have a country that likes to hide what it is up to. But, it also can cause harm in a modern society like ours, where such things end up on the web and can cause permanent damage. Unfortunately, it is a bit of a catch-22. We have the right to know issues and free speech rights smack up against privacy rights and serious damage of reputation for people who have not been convicted of a crime. The law will no doubt continue to shake out over the next few years as it struggles to catch up with the technology.

This post originally appeared on Quora. Click here to view.

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What Happens When You Flush an Airplane Toilet?
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For millions of people, summer means an opportunity to hop on a plane and experience new and exciting sights, cultures, and food. It also means getting packed into a giant commercial aircraft and then wondering if you can make it to your next layover without submitting to the anxiety of using the onboard bathroom.

Roughly the size of an apartment pantry, these narrow facilities barely accommodate your outstretched knees; turbulence can make expelling waste a harrowing nightmare. Once you’ve successfully managed to complete the task and flush, what happens next?

Unlike our home toilets, planes can’t rely on water tanks to create passive suction to draw waste from the bowl. In addition to the expense of hauling hundreds of gallons of water, it’s impractical to leave standing water in an environment that shakes its contents like a snow globe. Originally, planes used an electronic pump system that moved waste along with a deodorizing liquid called Anotec. That method worked, but carrying the Anotec was undesirable for the same reasons as storing water: It raised fuel costs and added weight to the aircraft that could have been allocated for passengers. (Not surprisingly, airlines prefer to transport paying customers over blobs of poop.)

Beginning in the 1980s, planes used a pneumatic vacuum to suck liquids and solids down and away from the fixture. Once you hit the flush button, a valve at the bottom of the toilet opens, allowing the vacuum to siphon the contents out. (A nonstick coating similar to Teflon reduces the odds of any residue.) It travels to a storage tank near the back of the plane at high speeds, ready for ground crews to drain it once the airplane lands. The tank is then flushed out using a disinfectant.

If you’re also curious about timing your bathroom visit to avoid people waiting in line while you void, flight attendants say the best time to go is right after the captain turns off the seat belt sign and before drink service begins.

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