Today I Found Out » Science

What the Things You See When You Rub Your Eyes Are Called

Daven — Wed, 08 Sep 2010 16:00:43 +0000

Today I found out what the things you see when you close your eyes and rub them hard are called, namely “phosphenes”.

A phosphene is characterized by perceiving some form of light when there is little or no light actually entering the eye, making it an entopic phenomenon (meaning the source of the phenomenon is within the eye itself). Phosphenes are most commonly introduced by simply closing your eyes and rubbing them or squeezing them shut, tightly; generally the harder you rub or squeeze, the more phosphenes you’ll see. This pressure stimulates the cells of the retina and, thus, makes your brain think you are seeing light. Specifically, Grüsser et al. demonstrated that pressure in the eye results in activation of retinal ganglion cells in a very similar way to how they activate as a response to light.

There are also several other ways phosphenes can be generated. These include through: electrical stimulation; intense magnetic fields; hallucinogenic drugs (phosphenes not to be confused with hallucinations, which are generated in the brain, not the eye); a blow to the head or a particularly severe sneeze where extra pressure is created in the eye on the retina and possible stimulation of the visual cortex; low blood pressure, which can be experienced if you stand up really fast after you’ve been relaxing; exposure to radiation; meditation or extended visual sensory deprivation; various side effects from medical drugs; and certain diseases of the retina and nerves.

Bonus Factoids:

The word phosphene comes from the Greek words “phos”, meaning “light”, and “phainein”, meaning “to show”.
The name phosphene was coined by JBH Savigny, who was a ship’s surgeon on the wrecked Medusa.
When phosphenes show up during meditation, they are more commonly known as “nimitta”. In Buddhist psychology and philosophy, this simply refers to forms, shapes, colors, sounds, etc. perceived during meditation. Prisoners who are being sensory deprived also occasionally will experience this phenomenon; in this case, it is often called “prisoner’s cinema”.
A phosphene is not to be confused with phosphine, which is a toxic and explosive gas.
The first documented electrically produced phosphenes were by neurologist Otfrid Foerster in 1929. The first documented reference to any type of phosphene goes back all the way to the ancient Greeks, though they didn’t call them phosphenes obviously.
Scientists Brindley and Rushton, in 1974, once successfully created a type of visual prosthesis that allowed certain blind people to see Braille spots using phosphenes. This device only works on blind people whose brains were capable of processing visual information, such as those who once could see, but lost their sight in an accident or the like. More recently, researchers have successfully developed brain-computer interfaces for certain blind people that create phosphenes such that it mimics what the person would see, if their eyes worked, so somewhat restoring their vision. Both these visual prosthesis work through electrically produced phosphenes.

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Why You Generally Shouldn’t Put Metals in the Microwave

Daven — Tue, 31 Aug 2010 15:00:44 +0000

Today I found out why you generally shouldn’t put metals in a microwave.

First, it should be noted that it is not unsafe to put all metals in the microwave. Indeed, you often put metals in the microwave anytime you put a hot pocket in the little pouch and place it in the microwave. The pouch has a thin layer of aluminum lining the inside that is designed to absorb the microwaves and heat up a bit so as to brown the outside of the hot pocket.

On top of that, the inside walls of your microwave oven are made of metal. This forms something called a Faraday Cage which traps the microwaves inside the box, so that they cook the food and not things around the microwave oven, like you. If you look closely, you’ll also see that the window you look at the food through has metal mesh lining it. The holes in this mesh are smaller than the wavelengths of the electromagnetic radiation your microwave is producing. This makes it so the waves can’t pass through the holes. Visible light, however, is comprised of much smaller wavelengths, so that form of radiated energy passed through the holes just fine, allowing you to see inside your microwave while it’s running without getting cooked yourself.

So if the inside of your microwave is lined with metal and certain food products, such as hot pockets and pot-pies, have containers that contain metal, why does your microwave manual say not to put metal in the microwave?

First, let’s talk a little about how a microwave oven actually works. At its core, a microwave oven is a pretty simple device. It’s basically just a magnetron hooked up to a high voltage source. This magnetron directs microwaves into a metal box. These generated microwaves then bounce around inside the microwave until they are absorbed via dielectric loss in various molecules resulting in the molecules heating up (more on how this works in the Bonus Factoids section). Matter that work well here are things such as water, ceramics, certain polymers, etc. These all end up converting microwave energy into heat quite effectively.

Metals, on the other hand, are great conductors of electricity, being packed with electrons that can move freely. Depending on the shape/type/thickness/distribution/etc. of metal, you may observe some heating of the metal itself in the microwave or none at all. You may also observe some arcing of electricity or none at all. In any event, when these microwaves hit the metal, free electrons on the surface of the metal end up moving from side to side very rapidly. This, in turn, prevents the electric wave from entering the metal; thus, the waves end up being reflected instead. However, there is also the potential that this ends up creating a sufficient charge density that the electrical potential in the metal object exceeds the dielectric breakdown of air. When this happens, it will result in arcing inside your microwave, from that metal to another electrical conductor with lower potential (often the wall of the microwave). In extreme cases, these electrical sparks can end up damaging the wall by burning small holes in the metal wall. It can also end up burning out the magnetron in your microwave oven or, in modern microwaves, can provide a surge that ends up damaging sensitive microelectronics, possibly killing your microwave or making it unsafe to use, in the case of a hole in the inner metal wall in your microwave.

Another way it can kill the magnetron of your microwave is when enough of the generated microwaves don’t get absorbed, such as if the food is wrapped in aluminum foil or mostly enclosed in a metal container. This can create a lot of energy not getting absorbed, with nowhere to go but eventually back to the magnetron, which can eventually damage the magnetron. Once again, killing your microwave oven.

On a more mundane level, something like a spoon or a metal plate or the like, positioned correctly, will simply make your food potentially not cook normally. On that note, it is once again, actually acceptable to put metal in a microwave under the proper conditions. Some microwaves even have metal grates inside for setting food on, such as is often the case with certain convection ovens. There are also certain types of metal pots and pans that are microwave safe. These all, however, are carefully designed to not cause any problems in your microwave oven. In general, putting metal in the microwave is unsafe, not because you are at risk of bodily harm or the like (though in extreme cases a fire might be started in your microwave), but, more to the point, primarily because it has the potential of damaging your microwave in the ways listed above.

Bonus Factoids:

Metal powder at room temperature actually does a good job of absorbing microwave radiation. When it does so, it heats up. It’s not wholly understood what is going on here; but it is known that if the metal particle size is less than 100 micrometers, the particle will absorb microwaves, instead of reflecting them. This is generally how the microwave pouches, such as come with hot pockets or pot pies, work; though, they sometimes use a form of ceramic instead, with the same effect of generating heat to brown the outside of the food. These pouches and containers meant for browning are known as susceptors.
It’s also generally a bad idea to run a microwave with nothing in it. This creates microwaves in the oven that have nothing to absorb them. This standing wave is reflected back and forth within the microwave, between the tube and the cooking chamber, and will eventually burn out the magnetron. This same effect can occur when cooking dehydrated food or, as noted previously, food wrapped in some sort of metal where there is very little to absorb the emitted microwaves.
The type of radiation emitted by microwave ovens is non-ionizing. This means that it doesn’t contribute to your chance of getting cancer like x-rays, ultraviolet light, etc do. Outside of potential burn risks, experiments done with rodents have yet to show any major adverse effect to prolonged exposure to microwaves at the 2.45 GHz range seen in most microwave ovens, even with continual low level exposure.
Bluetooth and IEEE’s 802.11 (like your wireless internet router probably uses) both typically emit microwaves in the 2.4 GHz band, very close to the frequency found in most microwave ovens. Radar and GPS also operate using radiation in the microwave spectrum.
Electromagnetic waves were predicted by James Clerk Maxwell in 1864. It wasn’t until 1888 though that Heinrich Hertz was able to build a device that was capable of producing and detecting microwaves. His device used a horse trough; Leyden jars; a zinc gutter (worked as an antenna); and a wrought iron point spark.
The first known documented use of the term “microwave” was in 1931 in a Telegraph & Telephone Journal: “When trials with wavelengths as low as 18 cm were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon.”
Microwave ovens work by having an internal magnetron emit electromagnetic waves around the frequency of 2.45 GHz (vibrates at about 2.45 billion times per second). These waves are absorbed by water molecules, fat molecules, sugars molecules, and certain other substances, which then heat up by a process known as “dielectric heating”. Basically, molecules such as water molecules are electric dipoles. This means that they have a positive charge and a negative charge on opposite ends. Thus, they will rotate themselves rapidly when trying to align themselves with the alternating electric field from the microwaves. As these molecules rub against each other, they heat up and, as they do so, they themselves also become part of the cooking process, heating up molecules around them that may not be absorbing much, or any, of the microwaves.
Microwaves are not nearly as efficient at heating frozen food due to the fact that the molecules are not free to rotate or move.
Microwave ovens do not “cook from the inside out”, as many people say. Microwaves actually heat from the outside in, very similar to other heating methods. The misconception arises from the fact that some foods that you microwave have a very dry outer cover (such as a crust), which the microwaves penetrate with little very little absorption. Thus, the liquid inside will appear to heat up first. This is why, with frozen objects, the center might remain frozen and the outer layer somewhat cool, while the layer just under the crust may be super hot. If it was truly cooking from the inside out, as people say, you’d never end up with that frozen center while the rest was super hot.
The particular band of microwaves produced by typical microwave ovens (2.45 GHz) was chosen primarily due to the fact that it is a frequency set aside for non-communication uses. Within the available frequencies that are not set aside for communication, 2.45 GHz was chosen because 433.92 MHz would require expensive equipment to generate sufficient power to heat food; 5.8 GHz and 24.125 GHz would require a much higher cost on electricity used to run the oven; and 915MHz was rejected as it wasn’t a band available world-wide, as 2.45 GHz was. 915 MHz, though, is occasionally used in industrial microwave ovens.
Even though most microwave ovens let you choose between power levels, there generally isn’t any change in the frequency level of the microwaves being generated. Rather, it simply changes the duty cycle of the magnetron. In other words, it turns on and off at a different rate.
A convection oven is basically just a conventional microwave that also has a way to brown food like a traditional oven. In order to provide this browning effect, the convection oven may use traditional oven heating elements or might use something such as a high powered halogen bulb.
The ability to use microwaves as a heating device for food was originally discovered by an engineer by the name of Percy Spencer. Spencer was working on building magnetrons for radar sets. One day, he was standing in front of an active radar set when he noticed the candy bar he had in his pocket melted. Upon noticing this, Spencer made the monumental mistake of telling other people instead of keeping it to himself and working on it on his own. He and some other experimenters began trying to heat other food objects, presumably to get out of actually working while they were at work. The first one he heated intentionally was popcorn. The second was an egg, which ended up exploding in the face of one of his co-workers. Spencer then created what we might call the first true microwave oven by attaching a high density electromagnetic field generator which would then shoot into a metal box, so that the electromagnetic waves would have no way to escape and the oven would be much more efficient and safe. He then placed various food items in the box and monitored their temperature to observe the effect.
The company Spencer was working for, Raytheon, then filed a patent on October 8, 1945 for a microwave cooking oven, eventually named the Radarange. This first microwave oven was about 6 feet tall and weighed around 750 pounds. The price tag on these units was about $5000 a piece. It wasn’t until 1967 that the first microwave oven that was both relatively affordable ($495) and reasonably sized (counter-top model) was available.
In 1971 only about 1% of American homes had a microwave. By 1986, that number had risen to about 25%. In 2009, the estimate was that about 90% of American households have a microwave.
It wasn’t until microwave ovens became extremely popular in the 1970s that they were commonly known as “microwave ovens”. Before that, they were typically known as “electronic ovens”.
Forks are particularly susceptible to sparking in a microwave due to the fact that their tines are relatively close together and will produce high voltage at the tips. This voltage will exceed the dielectric breakdown of air, which is about 3 megavolts per meter. The air then forms a kind of conductive plasma, which is the spark you see. This, in turn, makes the fork an even more effective antenna for the microwaves, worsening the problem.
Microwaves convert Vitamin B12 to an inactive form, which means about 30-40% of the Vitamin B12 in microwaved foods is not usable by mammals.
On the other hand, spinach loses about 77% of its folate when cooked in a normal stove, but retains nearly all of it when cooked in a microwave. In the same way, steamed vegetables, as a rule, tend to retain more of their nutrients in a microwave than when cooked in a traditional oven.
At one time, most long distance telephone calls were transmitted via a large network of microwave radio relay links, such as AT&T’s “Long Lines”. In the 1950s, about 5400 telephone calls could be run through a single microwave channel via multiplexing. The distance between hops was typically around 40-50 miles. The additional cost of transmitting this way was a large part of why long distance was so expensive historically. With the advent and installation of fiber optic lines and advanced satellite systems, this made the old ground based microwave relay links obsolete for transmitting long distance calls. (Although, satellite systems are essentially just a space-based version of this same thing).

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Why It is Nearly Impossible to Tickle Yourself

Daven — Fri, 27 Aug 2010 00:41:24 +0000

Today I found out why it is nearly impossible to tickle yourself.

It turns out, it’s very hard to tickle yourself because your brain anticipates things going on around you in order to help speed up response times. More technically, the cerebellum monitors body movements and can also distinguish between expected sensations and unexpected ones, generally resulting in diminishing or completely discarding expected sensations, while paying much more attention to unexpected ones.

So your brain is actively anticipating touch sensations. When it is doing this, it is also actively discarding sensations that it deems unimportant, like when you are typing and it significantly dulls the touch sensation in your fingertips so that you don’t really notice it unless you consciously think about it. This same type of thing happens when you try to tickle yourself.

Researchers at University College London tested this by scanning the brains of subjects while having the palm of their hands touched by themselves and by experimenters. The brain scans revealed that, when the touch was externally produced, the somatosensory cortex (involved in processing touch) and anterior cingulate (involved in processing pleasure) parts of the brain reacted much more strongly than when the touch was produced by the subjects themselves. In these cases, the brain was using information it has about, in this case, motor movements of the finger and arms and visual information, to anticipate the touch.

Interestingly, results from a different study showed that the same internal anticipated response applies when subjects manipulated a robot, which then in turn manipulated another robot to touch the subject’s palms. This was only true, however, when the associated touch from the second robot happened right away. When this happened, the cerebellum sends information on the sensation to expect to the somatosensory cortex. With this information, some unknown cortical mechanism is triggered that inhibits the tickling sensation from activating.

However, if the subsequent robotic touch is time delayed, even delayed by as little as a 1/5 of a second, the subjects felt stronger touch sensations, similar to when the touch was not self produced. By introducing the delay, it effectively tricked the brain into thinking the touch was externally caused, instead of internally caused and so didn’t inhibit the tickling sensation.

So in short, you can’t tickle yourself because there is no element of surprise. Your brain is using the various internal sensory data it has available to anticipate exactly what is going to happen based on your movements and visual data. When the anticipated reaction and the actual reaction line up, your brain diminishes or even sometimes completely discards the sensation as a result of that action. On the other hand, when someone else is tickling you, there are unexpected sensations on the skin and these then can result in the tickling sensation being activated.

Bonus Factoids:

Researchers at the Karolinska Institute in Stockholm, Sweden, studied fMRI scans between people who were actually being tickled and those who were about to be tickled and were anticipating it and discovered that the brain reacts the same to both. Specifically, the somatosensory cortex and the secondary somatosensory cortex both lit up at around the same levels. So even though, in the latter case, the subjects weren’t being touched, as far as their brains were concerned, they were being touched.
It turns out, the panic response when a tarantula is crawling on your leg or the like is exactly what is happening when you are getting tickled. The body’s response to being tickled is panic and anxiety. It is thought that this is a defense mechanism for exactly the type of thing listed above where an external touch, such as a poisonous insect crawling on you or the like, might be occurring. The body needs to react quickly to this unanticipated touch and without time for much conscious thought, so produces the panic reaction.
Interestingly, the panic reaction that results from tickling doesn’t feel like tickling when the person tickling you isn’t someone you want tickling you. In this case, it more closely resembles actual panic reactions, rather than having associated laughter.
A recent survey of college students indicated that on average only 32% of people report enjoying being tickled. Of the rest, 36% report disliking being tickled and 32% reporting being neutral on tickling. In the same study, they found people who reported disliking being tickled smiled more often during tickling than those who indicated they enjoyed being tickled. This is in line with other research that seems to indicate we smile and laugh during tickling due to nervousness, anxiety, and embarrassment.
The Romans used to use continuous tickling of the feet as a form of torture.
The word “tickle” comes from the Middle English word “tikelen”, meaning “to touch lightly”.
Being tickled by a very light touch across your skin is called “knismesis”. This type of tickle doesn’t usually produce laughter, but does produce the same type of panic response as the alternative form of tickling, called “gargalesis”. Gargalesis is the form of tickling produced by repeatedly having pressure put on ticklish areas.
Contrary to popular belief, most laughter is not associated with humor, but rather stems from non-humor related social interactions. This was discovered from a study covering over 2,000 cases of naturally occurring laughter, almost none of which stemmed from jokes or other such humor devices. Most cases were simple, short “ha ha’s” during somewhat normal conversations. These short laughs almost never interrupted speech, but rather occurred during breaks, providing social cues to those around. It is thought that laughter serves a similar function to yawning, namely providing “social glue” that helps bond people subconsciously.
Apes don’t laugh the way we do, but they do produce a panting sound in the same type of situations that humans would laugh in (being tickled; during play; etc). Likewise, rats will often produce a high-pitch sound when being tickled and during play.
This predictive system used by the brain for anticipated sensations is called a “forward model”, where the brain’s motor system makes predictions about the consequences of some movement or action and interprets the resulting anticipated sensations as self produced or externally produced. It then adjusts the level of the sensations felt accordingly.
This forward-predicting that your brain is constantly doing is also why you get startled and might even jump when you think you are alone and someone sneaks up behind you and taps you on the shoulder or says “boo!” This is the same type of bodily panic reaction as happens as a result of being tickled.

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Why Mint Tastes Cold

Daven — Fri, 20 Aug 2010 17:01:26 +0000

Today I found out why mint tastes cold.

Similar to why peppers taste hot, what’s going on here is there is a chemical in mint, menthol, which is tricking the brain into thinking that the area the menthol is applied to is cold; even though in fact, it’s the same as it was before. Specifically, menthol binds with cold-sensitive receptors in your skin; these receptors contain things called “ion channels”, in this case TRPM8. The menthol makes these much more sensitive than normal and thus tricks your brain into think you are feeling a cold sensation, when in fact, everything is more or less the same temperature as before.

This extra sensitivity is why when you eat peppermint, which has a relatively high level of menthol, and then you breath in deeply through your mouth, your mouth feels extra cold. Your cold receptors are reacting much more strongly than they normally would to the air which is cooler than the inside of your mouth.

Menthol is a compound classically obtained from various mint plants, though now is often synthetically produced due to the extreme high demand for menthol in a variety of products. Menthol is a waxy, crystalline substance that is somewhat clear or white. Interestingly, it is actually solid at room temperature and melts just a few degrees above room temperature.

Now for an experiment: Take a Jalapeno pepper and an Altoids Peppermint and eat them at the same time. What happens? … Seriously, someone want to try this and report back? Given that the capsaicin in peppers and the menthol in mint are both effectively fooling the brain into perceiving hot and cold using similar ion channels, despite no actual change in physical temperature, it would seem like that the two may well cancel one another out in the brain (how can one feel hot and cold coming from more or less the same receptors?); or at the least, one would think it would produce a very unique sensation. So do they cancel each other out or does one win-out over the other?

Bonus Menthol Facts:

Menthol can be used in solid form as “mineral ice”, as a substitute for real ice, if none is around. As far as your brain is concerned, the drink you drink with the menthol is cold, even though it might actually be warm. Makes for handy “icing” of your drinks on camping trips.
Mint leaves or mint oil containing high levels of menthol will also help repel mosquitoes and can even do more than just repel them; it has been shown that mint oil can actually kill the mosquitoes.
Menthol is very effective for providing short term relief for sore throats and other minor mouth and throat irritations.
Menthol is also effective at reducing muscle aches and pains, which is why it’s used in products like “IcyHot”.
Menthol was successfully isolated from mint by the Japanese over 2000 years ago, but has only been isolated in the western world since the 1770s.
Menthol is also used to treat sunburns, as it provides a cooling sensation (often used in conjunction with aloe).
Menthol is added to some cigarettes to reduce the throat and sinus irritation caused by smoking so that you can ignore even more warning signs from your body that you should really stop smoking.
Menthol works as a low level pesticide.

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Bananas Are Naturally Radioactive

Daven — Thu, 19 Aug 2010 15:49:42 +0000

Today I found out bananas are naturally radioactive. This comes from the fact that they contain relatively high amounts of potassium. Specifically, they contain Potassium-40, which is a radioactive isotope of potassium.

The fact that bananas are radioactive has actually given rise to the radiation unit: “banana equivalent dose” (BED); this is the average amount of radiation you are exposed to by eating one banana. The banana equivalent dose is occasionally used to help conceptualize the relative danger of various radiation sources and amounts; for instance, the amount of radiation typically leaked by a modern nuclear fission reactor. This leaked radiation is typically extremely small, typically in the realm of a picocurie, which is a millionth of a millionth of a curie. This latter measurement doesn’t make a whole lot of sense to most people, thus the banana equivalent dose was introduced to give an easy way to understand whether X amount of radiation is harmful or not, given that you know bananas aren’t harmful. For instance, living within 10 miles of a typical nuclear power plant will expose you on a daily basis to just a bit more radiation than you’d get from eating one banana a day.

Now before you start boycotting bananas because of the above association with nuclear reactor radiation leakage, consider that, to cause illness in a person, it takes about 100 rems. (Roentgen Equivalent Man: 1 rem = the quantity of ionizing radiation whose biological effect is equal to that produced by one roentgen of x-rays; basically, a measurement of how much radiation a person is exposed to.) So given eating one banana a day for a year only exposes you to 3.6 millirems, you’d need to eat about 10,000,000 bananas in order to reach that amount [100 rems * (1000 millirems / rem) * (365 bananas / 3.6 millirems)].

Not only should you not worry about eating bananas because of the radiation, but barring some major reactor meltdown, you shouldn’t really worry about living near a nuclear reactor either. In fact, recent research has even begun to indicate that these extreme low level amounts of radiation you experience from the cosmos, bananas, and the like, may actually be beneficial to your body. And as far as major reactor problems that might come up go, if you camped out at the plant at Three Mile Island during the accident that happened there in 1979, you’d have received only an additional 80 millirems of exposure during the duration of the accident. Granted, you’d need to eat about 8000 bananas to reach that level from bananas, but if you’ve ever had your spine x-rayed, you’d have received about double that just during the few seconds of the x-ray. If you were around ten miles away from the reactor during the accident, you’d have received about 8 millirems or about the equivalent of 800 bananas. There are no known deaths/cancers/etc that resulted from this event.

Public reaction to Three Mile Island was way overboard from what the actual event warranted as you can see from the banana equivalent dose. This was largely due to misinformation in the press; misunderstanding of radiation among the general public; and the fact that, not 12 days before it happened, the movie The China Syndrome was released. The plot of the movie was basically how unsafe nuclear reactors were and that just about everyone in the movie but one of the main characters was trying to cover it up. The China Syndrome movie title’s concept comes from the premise that if an American nuclear reactor core were to melt down, it would melt through the center of the Earth to China. Getting around the fact that it is actually the Indian Ocean that is on the opposite side of the Earth from the U.S. and the obvious problems with the “melt through the Earth” premise, it couldn’t have been a better timed movie as far as free advertisement through the press due to the Three Mile Island incident. The movie was nominated for several academy awards, including best actress by Jane Fonda.

So in essence, the banana equivalent dose is basically a measurement used to help quell the media hysteria that always surrounds nuclear reactors and other potential radiation sources like cell phones and the like. Basically, trying to show people that radiation is everywhere (literally) and most of it isn’t harmful at the levels we are typically exposed to, despite what you might read in the news.

On that note, for your reference:

If you live at high elevations, like Denver, Colorado, you are naturally exposed to about 50-70 more millirems per year than living in, say, Seattle, Washington (sea level).
Being next to the Rocky Mountains will net you exposure to about 40 extra millirems per year, due to the uranium in the soil.
If you live near the Atlantic Coast, you’ll get exposed to an extra 55 millirems a year from the air you breathe.
Every U.S. coast to coast round trip flight will expose you to about 5 extra millirems per trip.
A chest x-ray will expose you to about 8 millirems; a head/neck x-ray will expose you to about 20 millirems; a lumbar spine x-ray will expose you to about 130 millirems.
On average, a person living in the United States will naturally be exposed to somewhere around 360 millirems (36,500 bananas) of radiation per year, with the vast majority of that (300 millirems or so) coming from the sun, soil, rocks, and other natural sources.
If you sat about 1 inch away from your tv-set, you’d receive about .5 millirems per hour.
If you work with concrete a lot or live or work in a concrete building, you receive an extra 3 millirems or so a year.
At around 100 rems (about ten million bananas), you’ll contract mild radiation sickness. Early symptoms of this are very similar to the flu. This will also leave you more susceptible to infections, leukemia, and lymphoma.
At around 200 rems, you’ll start having damage to your gastrointestinal tract, which will cause nausea, bloody vomiting, bloody diarrhea, and abdominal pain. You’ll also start having damage to cells that multiply quickly, such as blood cells, reproductive cells, hair cells, etc. At this point, you’ll typically lose your hair, possibly permanently.
At around 300 rems, your body’s immune system will likely be permanently damaged.
At around 400 rems, you have a 50/50 chance of dying within 60 days if you don’t get immediate treatment.

Bonus Factoids:

Other common foods that are naturally radioactive include potatoes, sunflower seeds, many nuts, and kidney beans, among others. Among these, Brazil nuts are the most radioactive by far at 6600 picocuries per kg or about 1.875 BED (banana equivalent dose). The radium in Brazil nuts does not come from especially high levels of radium in the soil where the trees grow, but rather the very extensive root systems the trees develop, which cover a much larger area of the soil than most trees.
The Brazil nut tree is among the largest trees in the Amazon rainforest at around 100-150 feet tall and around 5 feet in diameter at the trunk. The tree can live up to around 500-1000 years.
Despite the name, the primary exporter of “Brazil” “nuts” is Bolivia, who account for about 50% of Brazil nuts exported world-wide. They are also not nuts, but rather seeds. So the whole name is a lie.
Brazil nuts are radioactive due to containing radium; your body doesn’t need radium, unlike the case with bananas and potassium.
Although bananas contain very little radiation, they are radioactive enough to trigger false alarms in some radiation sensors used to detect illegal smuggling of nuclear materials.
About 89% of the time Potassium-40 will decay into calcium-40 and 11% of the time it will decay to argon-40. This latter fact is important when dating rocks as the time elapsed since a rock last cooled from a molten state can be measured by looking at the levels of Potassium-40 and Argon-40 contained in the rock. This is because, when the rock is in a molten state, it releases the argon contained within itself. Once it is solid, it contains no argon initially. When the potassium-40 breaks down into argon-40, the argon cannot escape. This makes for a nice way to measure the age of a rock since it was in a molten state.
After the nuclear accident at Three Mile Island, local milk contained radiation levels of about 20 picocuries/liter. This is about 1/75th the banana equivalent dose (BED) in a 12 ounce glass of the milk.
Now the Chernobyl disaster was a whole different story, but that was a result of a lot of idiocy more than anything. It was a case where one of the reactors was intentionally put in about the worst possible state it could be in, all the while the operators ignoring all the warnings and overriding many of the automated safety systems. It was actually a testament to the safety systems that the reactor they were messing with lasted as long as it did with what they were doing with it. Even after the explosions, the workers who were managing the reactor next to the exploded one were told to keep the other reactors online and continue to work. It wasn’t until a few hours later that one of the engineers, Yuri Bagdasarov, made the decision to override his superior, Nikolai Fomin, and shut down the reactor adjacent to the exploded one and have everyone who wasn’t absolutely necessary for emergency cooling systems leave.
The mistakes didn’t stop there though, the exploded reactor crew chief, Alexander Akimov, assumed the reactor was still intact, despite all the graphite and reactor fuel lying around the building after the explosions. So he kept everyone working throughout the night on the exploded reactor core which cost many workers, including Akimov, their lives.
One of the problems was that, of the two dosimeters capable of measuring the radiation levels they were experiencing, one was inaccessible and the other failed to turn on. All the other meters couldn’t read that high; indeed, they didn’t read very high at all, so they only knew the radiation levels were somewhere above 3.6 rems per hour, which is a relatively high rate, but certainly not going to kill anyone working there for a shift. When they eventually brought a meter in that could read the correct levels, Akimov assumed it must be malfunctioning because of the extreme high readings they were getting. Once again, you’d think the nuclear fuel and graphite lying around the building and the two explosions would have tipped him off, but here we are. In his defense, at around 5000 rems, the brain begins to be damaged with the radiation killing nerves and small blood vessels. He wasn’t likely experiencing these levels where he was working, but lower high levels, while not causing brain damage, will cause memory problems; confusion; information processing ability problems; and decline in cognition. So that may have played a role in his poor decisions after the explosions.
The next mistake was with the rescue crews that arrived on scene. Many of them knew nothing of radiation and some even directly handled some of the radioactive debris lying around that was emitting as much as 15,000 rems per hour. The mistakes didn’t end there and, in the end, an estimated 60,000 people were exposed to high levels of radiation; of which, about 5,000 people died within five years of the explosion from problems stemming from radiation exposure. Note to self: when working at a nuclear reactor and there are a bagillion warning lights going off over the course of a few hours telling you to stop doing what you are doing, maybe you should think about not overriding said warnings and maybe, instead, stop what you are doing. I’m just throwing that out there.
Firefighters on scene at Chernobyl described the radiation as “tasting like metal” and feeling sensations of “pins and needles” all over their skin.

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Why Peppers Taste Hot

Daven — Wed, 18 Aug 2010 11:56:01 +0000

Today I found out why peppers taste hot.

The heat sensation is caused by capsaicin, which is a colorless, odorless, oily chemical found in peppers. Capsaicin binds with certain sensory neurons which then more or less trick your body into thinking that it is being burned or at least experiencing excessive amounts of heat in the area that the capsaicin comes in contact with, even though no actual physical burning is taking place.

(Warning, Extreme Nerdery Ahead) Specifically, what is going on is that the capsaicin is binding to the vanilloid receptor (VR1), which is a member of the superfamily TRP ion channel and thus is referred to as TRPV1; by binding to the VR1 receptor, the capsaicin molecule will produce the same sensation, or signal to the brain, that normal heat will produce when activating the TRP receptors. This is why eating peppers makes your mouth feel really hot, even though it’s not. (End Extreme Nerdery)

Interestingly, in extreme cases where exposure to capsaicin is high, such as in pure capsaicin extract, the sensation can be so “hot” that the body will be tricked into inflaming itself; so it would appear as if you are actually burned, even though the capsaicin doesn’t actually burn you at all, just tricks your brain into thinking it’s being burned. (Queue Matrix: Your mind makes it real.)

Capsaicin is not just a substance that makes your food extra tasty, it is also used in “pepper spray”, hence the name. Anytime relatively undiluted capsaicin comes in contact with your skin, particularly your eyes or breathed into your lungs, it will cause you to feel like you are being burned, even though you aren’t. So it makes a very effective deterrent without actually causing any real damage to the person being sprayed; or rather I should say causes no real damage if it’s not too strong a level of capsaicin as noted later.

There is even a scale for measuring hotness as a function of a chili pepper, the “Scoville Organoleptic Test”. This scale was developed by chemist Wilbur Scoville. The hotness is measured in multiples of 100 unites, referring to how much sugar-water was needed to dilute the pepper to the point where your brain is no longer tricked into thinking you are being burned.

Here are some examples of hotness levels on the Scoville scale:

Sweet Bell Peppers: 0 Units
Jalapeno: 2500-8000 units
“Standard” Pepper Spray: 25,000-2,000,000 units
Cayenne: 30,000-50,000 units
Red Savina Habanero: 350,000-577,000 units
Bear Mace: 2,000,000-2,500,000 units
Law Enforcement Grade Pepper Spray: 5,000,000-5,300,000 units
Pure Capsaicin: 15,000,000-16,000,000 units

*Warning: before you get all gung-ho to go out and purchase law enforcement grade pepper spray, “bear” mace, or really potent “regular” pepper spray for defense purposes, you should know that spraying that directly in someone’s eyes at close range is likely to cause permanent damage and in a lot of cases means you will be in as much trouble as your attacker if it can’t be shown they were actually trying to physically harm you. The low end stuff will tend to be just as effective in terms of deterring attack, but without the nasty probable permanent damage if sprayed directly in the eyes; so for self defense against humans, getting too strong of stuff can be a bad thing unless you are a police officer, then you can do what you want. Also, never spray “bear” mace against even a slight breeze, I can’t stress that enough. *looks at my brothers*

Most of the capsaicin in peppers tend to be centered around the seeds themselves. This is a defense mechanism that the plants use to keep fungus and animals/bugs that would destroy the seeds from wanting to eat the peppers. This is a very clever thing as it turns out. The capsaicin in the pepper fruit more or less stops everything that would destroy the seeds from eating the fruit; while at the same time, not stopping from eating the fruit those things that would eat the fruit and not destroy the seeds. Thus, the seeds pass undamaged through the digestive track of those animals and the seeds get spread around with ample fertilizer.

One of the animals that capsaicin has no effect on is birds. Birds also can’t really chew the seeds. Thus, when the birds eat the fruit and then pass the seeds through their digestive tracks, they deposit them all over the place. Interestingly, humans are one of the only “animals” that eat peppers that actually do tend to destroy the seeds through mashing them with our teeth. Almost all other animals/fungi/bugs that would destroy the seeds are more or less repelled by the capsaicin.

Capsaicin also has some nice medicinal properties to it as an anti fungal and anti-microbial agent. In addition, due to the capsaicin tricking the brain into thinking your mouth is being burned when you eat it, your brain will release endorphins thus producing a sense of well being. Also in response to being “burned”, your brain will boost your metabolism, among other things.

Ironically capsaicin is also currently used as a pain reliever, such as in cream for arthritis suffers with about a .05% level of capsaicin in the cream. How they do this is they first numb the skin, then apply the cream and wait for the patient to start feeling the heat; they then remove the cream. This method is very effective in reducing joint and other arthritic pains. Indeed, capsaicin is the primary ingredient in the drug “Adlea”, which is a very long acting drug to treat post surgical and arthritic pain. A single injection of Adlea to the site of the pain will reduce pain for up to a few months in the area injected.

Recently it has also been found that capsaicin is able to kill prostate cancer cells. In the study, the tumors that were treated with capsaicin ended up shrinking to about 1/5 the size of the tumors that were not in the control group. Capsaicin also has been shown to inhibit the growth of Leukemic cells. In yet another study, it has been shown to be effective in triggering Apoptosis in lung cancer cells, which is the process of programmed cell death.

Bonus Facts:

Peppers are a fruit, not a vegetable.
Capsaicin is fat soluble and thus water will be of no use in countering the burning sensation, other than the fact that if it is cold water it will temporarily overpower the capsaicin’s effect on the nerve receptors and tell your brain you are feeling a cold sensation. But once the cold water has gone, the heat will come back straight away not lessened at all until the capsaicin is gone.
Dairy products work best to counteract capsaicin because they contain a protein called casein which binds to the capsaicin, hindering its ability to bind to your nerve receptors.
A cold sugar water solution is almost as effective as drinking cold milk in terms of hindering the capsaicin from binding to your VR1 receptors, and thus muting the burning sensation.
Tarantula venom activates the same neural pathways as capsaicin, so getting bitten by a tarantula will feel much the same as being exposed to a high level of capsaicin.
Large enough quantities of capsaicin may cause your skin to turn blue-ish, severely inhibit your breathing, cause convulsions, and possible eventual death. However, the shear minimal amount of capsaicin in peppers makes it unlikely you’d ever come in contact with enough of this to have this actually happen, unless someone sprayed law enforcement grade pepper spray directly down your throat or something like that.

Sources:

Why Mosquito Bites Itch

Daven — Tue, 10 Aug 2010 17:00:08 +0000

Today I found out why mosquito bites itch.

When female mosquitoes poke their proboscis through your skin so they can suck some of your blood to be later used to make eggs, they inject you with some of their saliva. This saliva helps them to drink your blood more quickly, because it contains a cocktail of anticoagulants. Once the female mosquito is full up of your blood or is disturbed, she flies away, leaving some of her saliva behind. Your body then kicks your immune system in gear as a response to the presence of this saliva. It produces various antibodies which in turn bind to the antigens in the mosquito’s saliva. This then triggers the release of histamine.

Histamine is a nitrogen compound that, among other things, triggers an inflammatory response. It also helps white blood cells and other proteins to engage invaders in your body by making the capillaries of these cells more permeable. Bottom line, the histamine ends up making the blood vessels near the bite swell up. This produces a pink, itchy bump where the mosquito poked you.

Scratching the bump only makes this worse because it causes more irritation and inflammation of the sight, resulting in your immune system thinking it needs more antibodies to get rid of the foreign protein. So the more you scratch, the more it will swell; the itchier it will get; and the longer it will last.

Bonus Factoids:

Only female mosquitoes drink blood. They don’t need the blood for their own nourishment; rather, they need it to be able to produce eggs. Once the female has safely acquired a “blood meal”, she will rest for a few days while her body develops the eggs from digesting the proteins and iron in the blood, producing amino acids which are used as the building blocks for the synthesis of the egg yolk proteins.
Male and female mosquitoes alike get their nourishment from plant nectar and other sugar sources.
It is not uncommon to build up a tolerance to mosquito saliva, if you receive enough mosquito bites regularly over an extended period of time. This immunity will wear off after a couple years, if you cease to get bitten somewhat regularly.
Although you may see mosquitoes buzzing around at any time of day or night, mosquitoes tend to be most active a few hours before sunrise and a few hours after sundown. Their appearance at other times of the day tends to be as a response to being disturbed.
Some easy and effective ways to treat mosquito bites to reduce swelling and itchiness include:
- Applying a piece of Scotch tape onto the bite and leave it there for a few hours, then gently remove the tape. This will not only help remove some of the saliva that caused the itch, thus speeding up recovery time, but also will reduce the itch significantly in the process.
- Apply roll-on antiperspirant to the bite. The itching should stop almost immediately. The aluminum salts in the antiperspirant help the body reabsorb the fluids in the bite, which will reduce the swelling and get rid of most of the itching.
- Make a paste from baking soda and water and apply directly to the mosquito bite.
- Another paste to make is a paste from any meat tenderizer that contains papain. Mix it with water and spread it on the bite. The papain breaks down the proteins found in the mosquito saliva, which will help reduce your body’s reaction to the saliva.
- Soak a wash cloth in very hot water. This should be not so hot that it burns your skin, but should, nevertheless, be almost uncomfortably hot. Hold the hot wash cloth against your mosquito bite for a minute or two and repeat. This should cause the itch to disappear completely for at least several hours. This works by reducing the histamine-induced skin blood flow.
- Similarly, you could simply soak in a hot bath to achieve the same results.
- Another good home remedy is to apply nail polish to the bite. This might look funny, depending on where the bite is, but should reduce the itch considerably.
- Use some of the flexible membrane inside a chicken egg shell to cover the bite. As it dries and contracts on the bite, it will draw out some of the mosquito’s saliva.
- Rub a wet bar of soap over the mosquito bite. You should feel an almost immediate relief from the itch.
Mosquitoes have four stages to their life cycle: egg, larva, pupa, and adult. During the first three stages, they live entirely in water. During the larva stage, they feed on algae and other microorganisms and must frequently bob to the surface of the water to get air. During the pupa stage, they do not eat, but do sit at the surface and breath air through two small tubes. At the end of the pupal stage, the mosquitoes transform into adult mosquitoes and, after crawling to a dry place to rest and dry off, leave the water.
There are about 3,500 different species of mosquitoes throughout the world, including one type, of the genus Toxorhynchites, that doesn’t drink blood, but preys on other mosquito larvae when they themselves are in the larvae stage.
Adult female mosquitoes can typically live 4-8 weeks, but in the wild tend only to last about 1-2 weeks, due to a variety of factors including temperature, humidity, food sources, and predators. Adult male mosquitoes typically only live a few days after they mate, which tends to happen quite quickly after they reach adulthood.
Female mosquitoes detect possible blood sources primarily by detecting emitted carbon dioxide and octenol, which are both contained in your breath and sweat, along with a variety of other compounds which are lesser known in terms of which ones most attract mosquitoes. People who give off more of these compounds, such as people who sweat more, will be more attractive to these mosquitoes. The mosquitoes can typically detect these compounds up to 150 feet away.
A person whose body is more efficient at processing cholesterol is much more attractive to mosquitoes because the byproducts of this processing appear on the surface of the skin and seem to attract mosquitoes.
Female mosquitoes also hunt using sight. If you are moving around and your clothing contrasts with the background, the mosquito can zero in on you, even if they aren’t otherwise sensing you.
If the female mosquitoes are close enough, they can also find you using their heat sensors.
Mosquitoes annually transmit diseases to over two-thirds of a billion people or around 1/10th of the human population. About two million of these people die from whatever disease they received through the mosquito bite.
Mosquitoes that have similar anatomy to modern species have been around for at least 80 million years, with the first such specimen found encased in Canadian amber. It is thought that mosquitoes have been around for around 170 million years.
One of few effective mosquito and other bug deterrent, such as ticks, is DEET, which was created in 1940s by the United States Army; they were seeking to make a bug repellent for soldiers. It was first used as a pesticide and later used by soldiers as a repellent in 1946. It was released for civilian usage in 1957.
DEET has been proven to be by far the most effective bug repellent available to date. A repellent mixture with only a 23.8% concentration of DEET will protect the wearer for about five hours; 100% concentration of DEET has been found to be effective for about 12 hours. DEET works by confusing the mosquito’s sensors so that they can’t zero in on the location of the compounds stimulating their sensors, such as octenol. Recent research has also shown that mosquitoes, in particular, aren’t just having their senses confused, but also intensely dislike the smell of DEET. DEET also acts on the brains and nervous systems of insects and, in extreme cases, can cause paralysis and eventual death by asphyxiation in the insects.
DEET stands for N-Diethyl-meta-toluamide.
DEET works well as a solvent and can dissolve certain plastics, spandex, leather, and works as a nail polish remover.
Other less effective mosquito repellents include: picaridin, which is odorless, unlike DEET; metofluthrin, which is available in strips that you can place outside in areas you want mosquitoes to stay away from or can be used as a wearable form of repellent in a small container that you clip to your clothing;
Another effective mosquito “deterrent” is actually a mosquito attractant device that produces a lot of carbon dioxide and heat. This then lures the mosquitoes into the device where it traps and ultimately kills them. These devices placed near mosquito breeding grounds have drastically reduced mosquito populations in certain areas.

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What Causes Muscle Soreness After Exercising (Note: It’s Not Lactic Acid)

Daven — Fri, 06 Aug 2010 17:00:26 +0000

Muscle Cell

Today I found out what causes muscle soreness after workouts.

Since the early 20th century, this specific type of muscle soreness, called “delayed onset muscle soreness” (DOMS), was thought to be cause by lactic acid buildup in the muscles during strenuous workouts where your body’s oxygen supply is depleted. Recent research has shown this is not the case at all and has even shown that lactic acid is actually used by your muscles for fuel when oxygen supplies are depleted. This also flies in the face of popular belief (for more on this, see the bonus factoids section).

One would have thought that it should have been obvious that lactic acid had nothing to do with DOMS, due to the fact that this type of muscle soreness doesn’t appear until around 24-72 hours or so from the time you exercised, yet the lactic acid buildup only lasts in your muscles for at most an hour or two after your workout is complete. Nevertheless, it’s only been in the last 20-30 years or so that scientists have come to realize the actual role lactic acid plays in muscles.

So if it’s not lactic acid that is causing this soreness, what is it? Delayed onset muscle soreness (DOMS) is now understood to be caused by microfractures in the muscle cells themselves. This happens when you do some activity that your muscles aren’t used to doing or do it in a much more strenuous way than they are used to.

This is also why after you exercise some specific way a few times and allow your muscles to recover, that you won’t typically get sore again from doing that activity at a similar intensity level, so long as you continue to do it on a somewhat regular bases. The muscles quickly adapt to being able to handle new activities so as to avoid further damage in the future; this is known as the “repeated-bout effect”. When this happens, the microfractures typically won’t develop unless you change your activity in some substantial way. As a general rule, as long as the change to the exercise is under 10% of what you normally do, you won’t experience DOMS as a result of the activity.

For the more technically inclined, DOMS is caused by ultrastructural disruptions of myofilaments, particularly with the z-disk and with damage to the muscle’s connective tissues. Muscle biopsies taken a day after hard exercise often show bleeding of the z-band filaments that hold muscle fibers together. The pain then is thought to be largely due to this damage to the connective tissue, which in turn increases sensitivity of the muscle’s nociceptors (pain receptors); this then causes pain with stretching and the like, basically when using the muscles.

The delayed effect is thought to be as a result of the fact that the inflammatory process that ends up making the nociceptors more sensitive takes some time to happen.

Bonus Factoids:

Another common symptom of DOMS, beside the pain, is swelling in the muscles. You might notice, after workouts that cause particularly severe DOMS, that your muscles appear bigger than before. This isn’t because you’ve miraculously gained visible muscle mass in just one workout, but rather because your muscles are swelling as a response to the microscopic muscle tears.
Stretching before and after an exercise has long been considered a good way to minimize muscle soreness after a workout. However, recent research has shown that the effect stretching has on DOMS is negligible.
Methods that have been shown to minimize muscle soreness after workouts are any activities that increase blood flow to the muscles, including: massage; hot baths; low-intensity workouts; sitting in a sauna; etc.
Somewhat counter intuitively, you can also continue to do high intensity workouts to reduce muscle soreness. Experts still disagree on exactly why this appears to reduce DOMS, but it is thought to have something to do with exercise-induced analgesia. This is where your body increases pain tolerance thresholds as a response to exercise, particularly exercise structured around endurance training.
Recent research has also shown that extended warm up sessions, before exercising in some way your body isn’t used to, will also help reduce DOMS.
Alternatively, gradually increasing workout intensity, under 10% a week, should allow you to progress in your workouts while experiencing minimal or no muscle soreness.
When you first start exercising, you might notice a very quick boost in strength after only a few days of working out. This isn’t likely due to an actual significant change in your muscle composition; rather, that, as a response to exercising, your body will begin to increase the number of impulses that cause muscle contractions, which will give you a quick strength boost without your muscles actually having changed yet.
The process by which your muscles grow in length and increase in overall size is called “Muscle Hypertrophy” and is usually a response to physical exercise.
Scientists can tell how much muscle damage has occurred, which is causing DOMS, by measuring blood levels of CPK, which is a muscle enzyme. CPK is found in muscles and, when muscles are damaged, ends up being released into the bloodstream.
It used to be thought that having a nice long cool down period after exercising would reduce DOMS. This was because cool-down periods speed up the removal of lactic acid from muscles and it was thought that lactic acid was causing the muscle soreness. It has been more recently proven that cool-down periods after workouts have absolutely no affect on delayed-onset muscle soreness.
In food products, lactic acid is primarily found in sour milk products such as yogurt, cottage cheese, leban, koumiss, etc. Lactic acid is also commonly found in modern detergents, as it makes a good soap scum remover; is an anti-bacterial agent; and is environmentally friendly.
The idea that lactic acid was the cause of muscle soreness and fatigue dates all the way back to the early 20th century from research done by Nobel laureate, Otto Meyerhof. The specific research was where he cut a frog in two; placed the bottom half in a jar; then applied electric shocks to the muscles in the legs. After a few shocks, the muscles no longer would twitch. Dr. Myerhoff then examined the muscles and discovered they were saturated with lactic acid. Thus, lack of oxygen must lead to lactic acid, which then leads to fatigue. Because of this incorrect theory, athletes throughout the 20th century were taught to exercise only aerobically, where glycogen is used as fuel. Once they got to the anaerobic zone, lactic acid would buildup and damage their muscles and force them to stop working out for the day. It turns out, though, that these theories were incorrect, as shown by Dr. George A. Brooks who is an integrative biology professor at Berkley. He showed all the way back in the 1970s that muscles use lactic acid as fuel. It took many years and numerous other research projects, but eventually, his theory that lactic acid is actually used as fuel by muscles has been shown to be correct.
How muscles use lactic acid as fuel is as follows: muscle cells convert glycogen to lactic acid when there is not enough oxygen present to convert it normally to adenosine triphosphate (ATP); the lactic acid then can be used as fuel by mitochondria, which are the energy factories in muscle cells. The mitochondria have a special transporter protein that help move the lactic acid into themselves.
Lactic acid is extremely important because it allows the body to convert glycogen to energy without the need for the presence of oxygen, as with normal aerobic glycolysis (the process by which the body uses glycogen for energy). By converting to lactic acid instead of ATP, when there isn’t much oxygen available, it allows for the glycolysis process to last for several minutes instead of only a few seconds. Once your body has enough oxygen present, it can then go back to converting the glycogen to ATP and the lactic acid can be converted back to glucose by the liver and other tissues to be used later. This makes for much more efficient usage of glycogen when your body is low on oxygen.
Intense, endurance training can more than double the mitochondrial mass in your muscles cells, which can aid in your ability to use lactic acid as fuel. This allows your muscles to work harder and for longer periods in extended low oxygen situations such as when you are endurance training or the like. So one of the reasons trained athletes can perform at the level they do for as long as they do is because their intense training actually allows their muscles cells to absorb lactic acid faster and more efficiently due to larger mitochondrial mass.
Also contrary to popular belief, the buildup of lactic acid does not directly cause acidosis (increase in acidity in the blood that, among other things, is associated with causing a type of fatigue).
The system used by your body to give muscles their energy from the conversion of glycogen to ATP is known as an aerobic energy producing system. The system used by your body to use glycogen converted to lactic acid, when there is very little oxygen available, is called an anaerobic energy producing system.
One of the single best measures of cardiovascular fitness level, or more aptly, maximum aerobic potential, is called “VO2 Max”. This is a measure of the maximum capacity of a body to transport and utilize oxygen during exercise. This is often measured in liters of oxygen per minute (l/min) or milliliters of oxygen per kilogram of body weight per minute ((ml/kg)/min). The name comes from “Maximum Volume per time unit of O2″
VO2 max levels in untrained people are typically 40-60% higher in men than in women with the average VO2 max of an untrained man being around 3.5 l/min and the average VO2 max of an untrained woman being around 2.0 l/min. Interestingly, conditioning can more than double the VO2 max in some people and in others has little affect at all.
For reference, five time Tour de France winner Miguel Indurain at his peak had a VO2 max of 88 ml/kg/min. Seven time Tour de France winner Lance Armstrong at his peak was at 85 ml/kg/min. Cross country skier Bjørn Dæhlie had them both beat with a VO2 max of 96 ml/kg/min. Astonishingly, he achieved that in the off season. It is thought that his peak is likely over 100 ml/kg/min during the season, when he is in optimal physical shape.
For further perspective, typical thoroughbred horses have a VO2 max of around 180 ml/kg/min. Siberian dogs trained for the Iditarod have VO2 maxes as high as 240 ml/kg/min.

Sources:

Turkey Does Not Make You Drowsy After You Eat It

Daven — Thu, 29 Jul 2010 16:00:12 +0000

Today I found out turkey does not make you drowsy after you eat it.

Now to be clear, turkey does contain tryptophan. Tryptophan is an amino acid which the human body doesn’t naturally produce, but is essential to proper body function and, thus, must be acquired from food. The reason tryptophan is tied to drowsiness is that it is used by your body to create serotonin. Serotonin, among other things, acts as a calming agent in the brain and plays a key role in sleep. So with turkey containing tryptophan, one would logically say it would make you sleepy after you eat it… except, this isn’t actually the case.

So, why not? Primarily because of how we eat turkey and more importantly how the body deals with tryptophan. If you tend to eat turkey on a completely empty stomach and don’t eat anything else but a little turkey, then there’s a very small chance that the tryptophan in the turkey will make you a little drowsy right after you eat it. Add it to a sandwich or have it with some mash potatoes or really pretty much any other food eaten at the same time or just eat it on a non-empty stomach and it won’t be the turkey that is making you drowsy if you feel drowsy after.

It turns out, tryptophan needs to not only be taken on an empty stomach to have any instant effect, but also with little to no other amino acids or protein present in order to make you drowsy after you eat something that contains it. Given that there is a lot of protein in turkey and other amino acids, even if you are a bit malnourished, you are not likely to get drowsy from the tryptophan after you eat turkey, though it will increase your body’s store of the tryptophan.

What’s going on here is that when there are a lot of amino acids around, this causes competition among the amino acids as far as crossing the blood-brain barrier. Tryptophan is a particularly bulky amino acid so it ends up being at the back of the line, so to speak, and will generally stay there until those other amino acids are gone or, at the least, until quite a lot of them are gone so the ratio of tryptophan to those other amino acids is drastically increased.

So why do you get drowsy after, say, eating turkey on Thanksgiving or the like? Well, there are a lot of reasons, but primarily because, with your holiday meal, you likely just crammed a couple days worth of food into your body in the span of an hour or so, possibly with some alcohol, which is a central nervous system depressant that has a mild sedative effect. Also, with a full stomach, your body directs blood away from your central nervous system and other organ systems to help with your digestive system. More than anything, this is probably causing most of the drowsiness after a large turkey dinner, such as on Thanksgiving or Christmas or the like.

The “drowsy” effect is even more noticeable when your food contains quite a bit of various fats, which take a lot of energy to digest, and carbohydrates. Carbohydrates in particular release insulin. This results in a lot various amino acids being more or less swept out of your blood, being absorbed into your muscle cells, and thus the tryptophan to other amino acid ratio increases quite a bit, giving the tryptophan a better shot of crossing the blood-brain barrier and raising your serotonin levels.

Now there is typically always a nice store of tryptophan in your body at any given time due to the fact that it is not only prevalent in turkey, but also higher levels than in turkey per ounce can be found in chicken, beef, pork, cheese, chicken eggs (which contain nearly four times as much tryptophan per ounce over turkey), sunflower seeds, and many types of fish; it also is found, in lesser or similar amounts as in turkey, in milk, beans, sesame seeds, lamb, wheat flour, chocolate, white rice, oatmeal, potatoes, and bananas, among a lot of other foods. So your body is typically stocked full of tryptophan most of the time and eating some turkey isn’t going to significantly change your body’s store, though it will add some.

So, if you want to point to a specific food that can make you quite drowsy, it would be things high in carbohydrates such as pasta, mashed potatoes, breads, and the like; these not only cause your body to direct more blood towards your abdomen and away from other organ systems, which will make you drowsy, but also result in some of the tryptophan hanging out in your body to actually get a chance to make it passed the blood-brain barrier to eventually produce some serotonin.

Bonus Factoids:

For a nice healthy way to make yourself drowsy (as in not by stuffing yourself), boost your serotonin levels by eating a small, all-carbohydrate snack (no more than 30 grams of carbohydrates is necessary). This, in combination with the tryptophan already stored in your body, will give you a big boost in serotonin levels, according to Elizabeth Somer, MA, RD. Appropriate snacks here would be a few Fig Newtons, half a bagel with a little honey, a couple cups of non-buttered popcorn, etc. According to Somer, eating these small snacks right before bed has been shown to help significantly in getting a good night’s rest and is a healthy way to do so, unlike stuffing yourself or the like.
Serotonin is a neurotransmitter, which also can in turn be converted to melatonin, which is a neurohormone that is also used to regulate your sleep/wake cycle. Serotonin gets produced by tryptophan crossing the blood-brain barrier into the central nervous system. There, it is eventually converted into serotonin.
Ben Franklin fought hard for the Turkey to become the nation’s official bird, but he obviously lost out to the supporters of the Bald Eagle. His case for the Turkey being the national bird on the Great Seal is laid out in the following letter to his daughter Sarah Bache:
“For my own part I wish the Eagle had not been chosen the representative of our country. He is a bird of bad moral character. He does not get his Living honestly. You may have seen him perched on some dead tree near the river, where, too lazy to fish for himself, he watches the labor of the Fishing Hawk; and when that diligent Bird has at length taken a fish, and is bearing it to his nest for the support of his mate and young ones, the Eagle pursues him and takes it from him.
With all this injustice, he is never in good case but like those among men who live by sharping & robbing he is generally poor and often very lousy. Besides he is a rank coward: The little King Bird not bigger than a Sparrow attacks him boldly and drives him out of the district. He is therefore by no means a proper emblem for the brave and honest Cincinnati of America who have driven all the King birds from our country…
“I am on this account not displeased that the figure is not known as a Eagle, but looks more like a Turkey. For the truth the Turkey is in comparison a much more respectable bird, and withal a true original native of America . . . He is besides, though a little vain & silly, a bird of courage, and would not hesitate to attack a grenadier of the British Guards who should presume to invade his farm yard with a red coat on.”
So how much tryptophan should you intake on a daily basis? “If you’re getting even one serving of 3 ounces of meat, chicken, or fish; a couple of glasses of milk or yogurt; or if you’re eating beans and rice, you will get all the amino acids you need and in there will be the tryptophan,” says Elizabeth Somer, MA, RD.
In the 1980s, tryptophan became a popular supplement among those suffering from insomnia and those wishing to fall asleep quicker. These supplements typically contained about as much tryptophan as is present in two pounds of turkey meat and were taken daily. This was later linked to an outbreak of eosinophilia-myalgia, which causes muscle pain and sometimes death. As a result of this, the FDA banned tryptophan supplements, even though it was unlikely that it was the tryptophan itself causing this, rather, contaminated supplements.
Tryptophan was first isolated by Frederick Hopkins in 1901. He did so through hydrolysis of Casein, which contains about 4-8 grams of tryptophan per 600 grams of Casein.

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Shaving Does Not Make Your Hair Grow Back Thicker or Faster

Daven — Tue, 27 Jul 2010 10:37:00 +0000

Today I found out shaving does not make your hair grow back thicker, stronger, faster, or any other “er”. In fact, contrary to what parents the world over tend to tell their kids when their kids start shaving, it has been proven by numerous studies going all the way back to the 1920s that shaving has absolutely no effect whatsoever on your hair growth rate.

Hair growth is controlled by hair follicles found just underneath the skin. These follicles are not in any way affected by shaving. Only the outer part of your hair that is already dead is getting cut. The follicles underneath that determine thickness/color/growth rate remain completely unaffected by your shaving or not shaving.

How long back this myth has been widely thought to be true nobody knows; although, according to the New York Times, the myth has been popularly believed for at least 50 years.

One of the reasons people seem to believe this (beside just because their parents told them so) is that after they shave their hair and it starts to grow back, it seems much coarser or thicker even though it is not. If it were, inevitably everyone who shaves on a regular basis would eventually be covered in pencil-thick or bigger hair sprouting out of their bodies from every place they shave.

In fact, the reason behind this extra coarse feeling hair has nothing to do with it actually being thicker or anything of the sort. To see why it would feel coarser, think about holding a thin, long tree branch. When it is long, it will be somewhat flexible, allowing you to bend it a bit with little effort. However, if you cut that tree branch down to a few inches, you will no longer be able to bend it easily or possibly at all; it will suddenly seem much stiffer or stronger. The same type of thing is going on with your hair when you shave.

Some people also think it looks darker when it is growing back. This again is false and in fact why people believe this is a bigger mystery than the previously mentioned myth. If it were true, after a certain number of shaves, everybody’s hair would be black. There really is no reason to think it is getting darker, as once again, the hair follicles underneath your skin determine hair color and they are completely unaffected by shaving. It’s possible that people believe this, because, when they first start shaving, the hair tends to be quite a bit lighter than years later as they grow to adult hood. So perhaps they think this because through their pubescent years the hair darkens a bit naturally and so they think it’s because of the shaving when in fact the two have absolutely nothing to do with one another.

As far as the growth rate misconception, this more or less comes to the same thing. The hair follicles underneath the skin control it, so cutting away dead hair, isn’t going to do anything. People again likely think this one is true because when they first start shaving when they are young, their hair doesn’t grow that fast. Then as they become an adult, it grows much faster than it did when it first started popping up on their bodies. So they might misconstrue this to have been caused by shaving (and probably just like the previous one, backed up likely by their parents at some point when they first started shaving telling them that shaving will make their hair grow back thicker/darker/faster). But in the end, this line of reasoning is kind of like thinking the sun comes up every day because your alarm goes off every day around the time it comes up.

Now with waxing it is possible to affect the thickness and other aspects of hair regrowth. However, it will never be the case that the hair will grow back thicker/darker/faster. In fact, by waxing you are damaging the hair follicles underneath the skin; over time as you wax more and more, the hair will grow back less and less and even sometimes will get lighter colored and thinner. So though waxing, unlike shaving, actually does affect your hair growth, it more or less affects it in the opposite way most people think shaving does.

Bonus Hair Factoid:

Many people believe that brushing your hair is good for it “Got to get your one hundred strokes a night in.” In fact, it is actually quite bad for your hair. It pulls out healthy hair that wasn’t yet ready to come out, possibly damaging hair follicles in the process; it also breaks healthy hair and scratches your scalp. Because of this, it’s actually best to keep hair brushing to a minimum.

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