ELI5: how did women shaving their legs/armpits come about and why did men not do it too?

ELI5: how did women shaving their legs/armpits come about and why did men not do it too?

ELI5 If symptoms of a cold serve the function of ridding our body of the illness, then do cold medicines that reduce these symptoms slow our recovery?

ELI5 If symptoms of a cold serve the function of ridding our body of the illness, then do cold medicines that reduce these symptoms slow our recovery?

ELI5 When we have a cold/illness, symptoms like coughing, sneezing, and runny nose are our bodies’ way of getting rid of germy mucous. If we take medicines that reduce these symptoms, are we hindering our bodies’ natural method of recovery?

ELI5 why is it that we always see so many new awesome ways to fight cancer and yet it seems nothing of it is ever being used?

ELI5 why is it that we always see so many new awesome ways to fight cancer and yet it seems nothing of it is ever being used?

I mean, I see articles every week here on reddit about a new way to kill cancer cells etc. And it's been like that for years and yet none of these ever seem to be used to actually treat people.

There are three main factors here.

One is that medical treatments tend to get most of their news coverage when they're in early development, since that's when they're novel. It takes years for a new medical treatment to get from "we're pretty confident this will work" to mainstream usage, both because there are a lot of processes to follow to make sure it's actually safe and effective, and because when it's new it's really expensive and so the existing treatments continue to be used in some cases.

The second is that unless you're an oncologist, you probably have no idea what methods are actually being used to treat cancer. Some of them are things you heard about a decade ago and now are the best choice and are used routinely, but there's no reason for you to know that. Survival rates for almost all kinds of cancer have gone way up in the last few decades, and while some of that has been due to improved detection, a bunch of it is new treatment methods. The 10-year prostate cancer survival rate has gone from 25% in 1971 to 84% in 2011, for instance.

The third is that cancer treatment progress is incremental. It's incredibly rare that a new treatment or prevention method comes out and cuts the mortality rate for a kind of cancer in half or more. More commonly, a new treatment will come out that cuts the mortality rate by, say, 2 percentage points. For a common kind of cancer, that can be thousands of people per year that live when they would previously died, but it's not going to make that kind of cancer a non-issue. Cancer research is largely about stacking up a bunch of advancements like that, though, so that it can incrementally become less and less deadly.

Obligatory relevant XKCD

Randall did a great job of identifying the problem with new drugs - sure, they kill cancer, but they also kill you. There are a million ways to kill cancer that we already have, but killing cancer while leaving the host alive is another problem.

There's also the little problem that various types of cancer are weak to different things. It's like pokemon, in a way : you see a grass type, you use a fire move. You see a lymphoma, you use radiotherapy. There are many, many types of cancer, and they all demand slightly different methods of treatment.

Back to the subject. So we find this new magic drug VAPE420 that supposedly kills... idk, renal cell carcinoma cells really well. Eureka! Call the news! VAPE420 hits the headlines. We now have to make VAPE420 into an actual clinical drug. First, we make sure it doesn't kill too many normal cells in a petri dish. We then move on to mice. Does it kill them? No? Good. We then test them on healthy human volunteers. Phase 1. Does it harm them? Hopefully not! Good, they seem to be okay. We now test them on patients. Phase 2. Does it seem to work? Good. We now test it on even more patients. 3. Are there any major side effects etc? No? Great. We finally are able to sell the drug to the public, which starts Phase 4 of drug testing : feedback. This whole process can easily take 10+ years for a single drug. Congrats, you now have a single fire-type drug. We now need to make a water-type, a grass-type, a ground-type, etc etc etc.


There are many types of cancer.

Different drugs are used for different types of cancer.

Drugs that kill cancer can also kill you.

Testing takes a long time so they won't kill you.

Many types x long time = ?

Oncology BioPharm employee here:

Awesome research is done every single day. Some at my company, some at the university level, some at government labs. Finding the 'cure' is relatively easy. Developing it, is not.

You need to do ph0 or tox trials, this involves animal studies. Many great drugs die right here due to high toxicity. Remember cancer cells ARE human cells. The key is to be able to remove only cancer cells. Lots go away here.

Then you need to do ph1 trials, this takes data from tox trials and starts dosing people, here you'll find out if the animal models predict toxicity to people. Lots fail here due to unexpected things.

Then ph2 comes up, now you're looking to see if this treatment actually works. "works" is the key point. You can't do a null placebo, so you need to 'work' better than the standard of care. Lots fail here.

Then ph3 which expands on dosing knowledge from ph2. Lots fail here.

All of this takes years. Typically from discovery, you need a good 10+ years to do the trials above, plus the insane amount of characterization of the molecule and ALL of the degradation pathways with complete stability profiles for the drug expiry period.

There is a huge lag time between treatment discovery and actual usage. Not to mention probably 90% of the discoveries you see in the papers never make it to the hospital, after testing reveals significant side effects, or that it doesn't work in humans only mice, or some other reason.

Also the non-science media likes to hype up discoveries far more than the researchers are comfortable with. Headlines like "miracle cure" and "life saving treatment" are rarely that, and even the researchers discovering them wouldn't describe them like that.

ELI5: how do the likes of ALDI get away with clearly copying branded products labelling?

ELI5: how do the likes of ALDI get away with clearly copying branded products labelling?

You go to Aldi and the washing powder looks just like a leading brand. The cakes look like mr kiplings etc etc it's clearly meant to be misleading but they don't stop it?

In at least some cases, products sold at Aldi are in fact made by the big brands, but under a different name. When you pay more for a big brand, you're really just paying for the name on it. In Germany you can actually buy books listing all of Aldi's "generic" brands and telling you which companies actually make them.

In the US, It's not illegal to copy or "knock off" packaging (which generally falls under the "trade dress" category of trademark law) as long as the reasonable consumer would not be mislead. And only distinctive design features are trademarkable at all. In other words you can put your detergent in an orange bottle with a blue cap, but as long as it's clearly called "Waves" in big letters, not "Tide" the reasonable consumer would not think they're buying Tide, you're only using nondistinctive features and you'de be fine.

Most "generic" products are produced in the same plants that make "name brand" products. They are the same product, owned by the same companies, just branded differently.

I’ve never seen a store brand that was actually meant to be misleading. They’re almost always merchandised immediately adjacent to the thing they’re a copy of. Similar packaging helps you know that it’s a copy of the thing to the left rather than the thing to the right.

ELI5: How does a hypodermic needle not just get gummed up with a core sample of the flesh it pierced into?

ELI5: How does a hypodermic needle not just get gummed up with a core sample of the flesh it pierced into?

A needle is shaped so that the flesh goes around the needle, not through it. The front of a hypodermic needle is 'beveled', which means it has a slanted shape. You put the pointy side to the skin when you go in, and it separates the tissue so it doesn't go into the hollow part of the needle. It also (usually) makes it less painful as it pierces less nerves on its way through.

It's kinda hard to explain, but very simple when you take a look at the cross-section.

It is because the needle is beveled. So there is actually a right and wrong way to insert a needle. If you were to insert a needle bevel side down, it would be a lot more painful.

Hypodermic needles have a beveled tip. This effectively means that the hole on the needle points in a different direction to which the needle is cutting. The shape of the bevel cuts the tissue and pushes it away from the hole.

Some needles are designed to plug up with tissue, and these are used to take a sample of organ tissue, and these have a hole at the front edge and a straight cut and sharpened tip. You insert the needle onto the organ, the needle plugs up, and you twist the needle to break off the plug, pull the needle out and push a rod down the needle to extract the plug.

An air embolism is a collection of air bubbles that block the flow of blood, much like a blood clot would. It can block or limit blood flow to important tissues in the body, such as brain matter, and cause many complications.

Eli5: What's the difference between OTF and TTF fonts?

Eli5: What's the difference between OTF and TTF fonts?

Hi. I make fonts for a living.

TrueType and OpenType fonts are mostly the same thing.

There are two things that make them different:

TrueType fonts are drawn using Quadratic Outlines, which is a very formal way of drawing letters. OpenType fonts use Postscript Outlines which is a much easier way for designers to draw fonts. You can't see the difference when looking at a font, but it's something a type designer has to think about when drawing the letters.

The other difference is how each font uses "hinting". Hinting is special rules that tell the computer how to show the font on a computer screen.

TrueType has lots of rules about how it should look, and because of this, a hinted font will usually look better on a computer screen. PostScript has some simple rules and mostly lets the computer decide how it should look.

TrueType fonts can have a .ttf or .otf extension, and OpenType fonts can only have a .otf extension.

Most people can't see these little differences, so you can use either OpenType or TrueType fonts. When you're working in a job that uses a lot of fonts you might need to use one format or the other. Graphic designers who work in print usually use OpenType fonts. Web designers usually use fonts that start out as TrueType fonts. And a lot of architects need to use TrueType fonts in their programs.

Last thing, kids: fonts take a lot of work to make and a lot of people work very hard to drawn new and interesting fonts. So please use your allowance to buy fonts and don't steal.


assuming OTF is CFF-OTF/Type 1 outlines, even though OTF is a wrapper around CFF or TTF outlines. manual hinting is better than no hinting or autohinting.

TTF stands for True Type Font , a relatively older font, while OTF stands for Open Type Font Open Type Font, which was based in part on the TrueType standard. Both are file extensions (.ttf,.otf) that are used to indicate that the file is a font, which can be used in formatting the documents for printing. They are distinguished primarily by their different outline formats and the contrasting approaches employed to rasterize those outlines.

OTF also supports ligatures (e.g. fi and fl as a single character) and choice of uppercase and lowercase numbers, among the things that were already mentioned.

OpenType (OTF) allows for more advanced use of text/glyphs/symbols than TrueType (TTF). It was developed in a way that allows font develops better, cleaner looks when using more "complicated" text use than simple alphanumerics. This includes any use of multiple languages, symbols, mathematical symbols with better support for Unicode. OTF better handles any changes in the positioning, size, and layout of the characters.

Simply put OTF is better for advanced typology or use of special characters. They are largely equivalent in their coding of how they represent characters and for standard usage of alphanumeric characters. If you have a choice between OTF and TTF, because of its broader application OTF is preferred.

ELI5: Trains seem like no-brainers for total automation, so why is all the focus on Cars and trucks instead when they seem so much more complicated, and what's preventing the train from being 100% automated?

ELI5: Trains seem like no-brainers for total automation, so why is all the focus on Cars and trucks instead when they seem so much more complicated, and what's preventing the train from being 100% automated?

I've been a Locomotive Engineer for the BNSF Railway for 10 years. The first answer to your question is that the Brotherhood of Locomotive Engineers and Trainmen (Engineers Union) is the oldest in the country at 152 years and we have fought tooth and nail to keep our jobs. That being said, the second answer is a little more complicated.

The bulk of modern road locomotives are manufactured by General Electric. A road Locomotive is a six axle 4400 horsepower engine that is meant to travel at track speed between cities. This is opposed to a yard Locomotive which is four axles and only meant to travel at 10 mph in short intervals though it is capable of track speed (up to 70mph).

A General Electric Locomotive comes with proprietary software in the locomotives heads up display called the GE Trip Optomizer. The T.O. as we call it is essentially auto pilot. Once engaged, it is capable of speeding up or slowing down the train at speeds of 12-70 mph. It uses algorithms to determine how to handle the train in the most fuel efficient manner while managing "in train forces," but more on that later. The T.O. Uses GPS to determine exact locations to comply with both permanent and temporary speed restrictions. In my experience the T.O. Is accurate within 50 feet which is nothing short of miraculous considering the computer has to discern variables such as train tonnage (weight) both as a whole and individual cars and where they are placed in the train. Also train length and curvature of the territory. Whether or not you are on an ascending or descending grade (up a Mountain or down one).

As an Engineer in 2017 I am needed at the controls of a Locomotive for the following reasons. First, T.O. Doesn't always work, nor is it present in all of our locomotives (some are made by EMD.) Second, T.O. Doesn't work at speeds below 12 mph, so I have to start the train out and then engage the T.O. Once I get over 12. Third, T.O. Only works when I have authority to travel at track speed for a great distance. For example, if I have authority for 6 miles or more, I will engage the T.O. If I have to stop at some point within about six miles, I have to take control of the train and get it stopped at the correct location while complying with good train handling procedures. The T.O. Is only able to operate at maximum authorized speed all the time. It does not stop the train. That is the job of an engineer. Imagine a self driving car that can only handle itself on Interstate highways at the posted speed limit and cannot drive down a street with traffic lights and comply with the signals. Same concept.

Stopping the train without snapping it in two is the main job of a Locomotive Engineer. It's like a musician making music with an instrument. It takes training and experience. There are two types of brakes used on a train. First are the Dynamic Brakes, which are only found on Locomotives. That is where each axle acts as an electric generator. Imagine a hand crank emergency radio or flashlight. When you turn the crank there is resistance on the handle which is generating power. We use the resistance on each axle to slow down the train by generating electricity. We then literally throw away all that valuable electricity by dissipating it as heat out the top of the engine. It's a tremendous waste but hey, that's how we roll in America.

The second type of brakes that we use and probably the biggest reason to keep trains manned is the Westinghouse Air Brake System. Each rail car is equipped with brake rigging which operates entirely on compressed air. There are no electrical components, everything is mechanical. There are air compressors on the locomotives that are connected to each car through the use of air hoses and the entire system is controlled by the engineer at the head end of the train. The speed of the train can be controlled by either taking away air (setting the brakes) or adding air (releasing the brakes). I know that sounds backwards but that's how the system was designed.

It is the Westinghouse air brake design that truly throws a wrench into the need for automation. You see, Westinghouse designed this system in the 19th century. That's right, the flipping 1800s. The Titans of industry at the time began to expand the railroads so rapidly that there was only time enough to redesign the system to be more efficient once. That also happened in the 1800s. So that means that in 2017 we still use this system to stop our trains. Every rail car on every piece of track in the United States has this type of brake rigging. And according to federal law, each car has to have tested, inspected and working air brakes BEFORE the train departs it's initial terminal. A Conductor, (that's the other guy in the cab) has to walk the entire length of the train three times before the train can depart, once on each side to ensure the brakes are set and once to ensure the brakes have released. That could be up to 7000+ feet three times (5280 feet in a mile!)

The Westinghouse air brake system, although used industry wide, has its flaws. The brakes have a tendency to "dynamite" or begin braking without warning. Imagine the brake on the rear car braking a full capacity and no other brakes in the train are working. This type of event cracks the whole train like a whip and the Conductor and Engineer are at the tip. At the very least we'll get greasy face prints on the windshield. At the worst we're looking at a train broken in two or possibly a derailment. In the remote locations that the railroad travels in, it is the job of trained professionals like us to inspect the train, possibly change a broken knuckle on a car (60 lbs), put the train back together (do another air test) and get on our way.

In using a temperamental system like this it falls upon he job of a human being to orchestrate the movements of the train through the use of his senses. Feel, what's going on behind you? Is there more slack in the train than you expected? Sound, are the brakes squealing? Is it possible that they are not all the way released? Smell, do you smell hot brake shoes? The smell of burnt rubber? Sight, look back at the train on a curve. Is it on fire? Is there dragging equipment? Taste, what's in my lunchbox? Is it time to put my steak and potato in the engine compartment to heat it up yet?

These are things that automation cannot replace, human intuition in the middle of nowhere.

Trains are almost 100% automated. Control of railroad switches is more and more centralized. Building of the rail path is automated. Most of the railroad staff is there just in case the automatic system fails or power outage. Railroad companies know that even if they automatize it further it will not reduce the staff significantly so they aren't pushing for more automatization anymore.

Lots of good comments here, about the non-deterministic things that humans do, the stakes (hundreds of passengers), and the remarkable extent to which trains are already automated.

However, there's one thing I don't see here yet: How much more efficiency can you gain by eliminating people entirely from trains? If a train carries 500 passengers or 100 cars of cargo, and has a technical staff (i.e. driving, navigating, communicating) of three or four, we're not going to change economies much by eliminating those three or four people.

The answer depends slightly on the region we're talking about, so I'll focus on the one I know most about, Europe. Things might differ slightly elsewhere. It's also going to be a bit more technical in nature.

TL;DR: It's much more expensive and difficult to automate trains, because of regulations, the lifespan of the rolling stock, and the infrastructure involved.

As others have already mentioned, a huge chunk (if not everything in someplaces) of the actual railway infrastructure is already automated, such as signals and switches. Computers have made humans mostly obsolete there already: We've used to have many and big mechanical systems to prevent mistakes, today it's a single computer easily dealing with large regions of the network.

Europe strives to have an unified system (ETCS) which controls trains (and their safety measures), which means that a train can go from one point of Europe to the other without having to switch engines or even drivers. There are multiple levels, which bluntly put refer to the available technology on the rolling stock and the infrastructure. The lowest level is still using the "normal" signals, whereas the highest levels are not using signals at all, but requires trains to have a constant radio connection to a control center.

Lower ETCS levels do not offer you much choice in the way of automation, higher levels do. However, this is costly, as you need to upgrade your engines (which can easily last 50 or more years, and are expensive to replace) and add additional security infrastructure (cell towers to provide the radio connectivity). Depending on your geography, the latter can be tricky.

So one point is the cost of actually getting a system that we can safely automate. Another one is trust. Put differently, when asked "Would you like to enter a metal box that's going very fast next to other boxes that are going very fast, and all these boxes are controlled by some computer very far away?", the answers you would get would probably be rather... conservative. Even with the amount of security we have these days, the software still has (smaller) flukes from time to time. A trained human operator can notice these mistakes and question the computer's decision, something that computers themselves have a harder time to do.

Another one is the security bit. Train tracks are often exposed due to their nature, and might even include dangerous zones such as railroad crossings or stations without under-/overpasses. A human driver can see those dangers and act accordingly. More importantly, they can see it on other tracks as well and warn other drivers. Because there's no real guide to how to build rail networks and most of that stuff has grown historically in any case, it's difficult to teach a computer to do that. It gets even worse when you consider that sometimes obstacles are allowed between tracks - for example posts for overhead wires, or signals.

In addition to that, the age of the rolling stock comes into play again. One part of being a train driver is to check the train for anything suspicious during the journey, especially on freight waggons. This can include brakes or axles that are running hot, or tarpaulins that have loosened and are now threatening to touch something (e.g. the overhead wires). We have systems on the railway tracks that can detect those, but not everywhere (they are usually placed in front of tunnels or terminus train stations), and they can't detect everything. The rail cars themselves are usually old and feature little to no technology in that regard, especially since they're usually used internationally and regulations (and therefore standards) vary from country to country.

Which brings me to the regulations: Depending on your country, railways are more or less regulated. Some of these regulations may make automation impossible, or just way too expensive. Especially if there was no push towards automation so far, chances are that some law changes will be required before you can even start thinking about upgrading.

ELI5: Why do some people pay others to play online games for them?

ELI5: Why do some people pay others to play online games for them?

The answer is actually kind of two-fold.

1. People want to be seen as “good” without putting in the necessary time it takes to rack up experience. Some people don’t have the time to spend grinding away to get better ranks, sites like this and others like it exist as a way to cater to this group of people. Most players hate that you can pay to look better than you really are (unless you’re great and just have no time at all, but that’s hardly ever the case.). There are some legit reasons for it, maybe you have friends who are at a higher rank than you in a game, or maybe you just want to play with better competition. Some streamers do this to build their Twitch or Youtube userbase as well. Have you looked at how many gaming channels there are on Youtube lately? Some with hundreds of thousands or millions of subscribers. There is big money to be made on there if you are seen as a pro in your chosen game. For these people, it’s more of an investment.

2. They don’t have the skills to rank higher on their own Some people just can’t get to higher levels by themselves. Paying someone to do it for them is kind of like a shortcut, but most would call it cheating. I frankly don’t care if someone wants to shell out their own cash to play at a higher rank, it usually just ends up in more kills for me! The people who do care are the ones getting killed constantly by a pro who is essentially grinding an account for someone else. to become apparent quickly if you belong or not at the level you paid to get to on most games. If you’re really bad, you probably need to hone your skills at lower levels or else you might just end up running around and getting killed a lot.

Either way, it’s going to become apparent quickly if you belong or not at the level you paid to get to on most games. If you’re really bad, you probably need to hone your skills at lower levels or else you might just end up running around and getting killed a lot.

Many video games have rewards, earned through play, that can make the experience more enjoyable once they have them (unlockable powers/weapons, cheats, etc.). Sometimes, the process of obtaining these rewards is less fun than normal game play. This is why some game developers offer the option to exchange real money to have these rewards instantly. However, some game developers do NOT allow players to purchase the rewards directly, and thus the rewards can only be earned through play.

A person with limited free time but plenty of disposable income wants to make what time they spend with their video games as enjoyable as possible. Therefore, they pay for in-game content that they think will enrich their experience. And if the game does not allow for that, they hire someone to play the game in their place and earn these rewards for them.

He wants the prestige and the community of being a top-ranked player but doesn't have the free-time it takes to get that ranking.

More often than not, these people drag their teams down but he thinks he deserves to play the game at a high level.

its called boosting which is where you pay someone to boost your account to a higher ranking.

ELI5: Why do we become clear minded after an orgasm?

ELI5: Why do we become clear minded after an orgasm?


ELI5: Why do we become clear minded after an orgasm?

Because men are pretty simple creatures driven by a few base desires, with the need to reproduce being paramount.

Feeding is another of these base desires, and when we are hungry hormonal changes and changes in blood sugar combine to make us focus more intensely on acquiring food.

It's the same with sex. When we are seeking sex and our senses pick up that a chance to spread our seed is imminent (pheromones, touch, etc.), we tend to focus almost solely on achieving orgasm at the expense of most other things.

Once we climax and our blood pressure normalizes, we almost immediately move on to ensuring that the other base needs in the hierarchy are met. Hunger - we want a sandwich. Rest - we want to nap. Safety - we want to leave before her husband gets home.


As a guy I've only ever felt immediate shame and the need to be clothed. That's normal, right? Right?!

...right? :::whimper:::

I wouldn't explain this to a 5 year old, but I am curious about the answer.

Try one of these subthreads