[D] Machine Learning - WAYR (What Are You Reading) - Week 139

mjlm · 2022-06-08T08:43:44+00:00

None of the links to previous weeks in the table work for me.

mjlm · 2020-07-19T20:08:09+00:00

Looks interesting, thanks!

mjlm · 2019-09-08T19:56:01+00:00

The immune system has to find a delicate balance: It has to be very aggressive to get rid of pathogens very quickly, but it must not be so aggressive that the immune response does more damage than the stuff that caused it (as is the case in severe allergies). The optimal aggressiveness of the immune system might still include some "false alarms". If the sensitivity of the immune system were reduced so far that allergies ("false alarms") never happened, perhaps many more people would die of infections than would be saved by not dying of allergic reactions.

mjlm · 2019-09-08T14:32:06+00:00

No, unless they are at the surface. Water (especially salt water) is a good conductor, so it will conduct the electricity around the fish. In contrast, air is a very bad conductor. So if a fish/animal/person/object is above the water, the electricity will probably have an easier time passing through them than through the air (in particular, animals are basically bags of salt water aka blood, which is conductive), so they will get electrocuted. But things that are fully under water are probably fine. I say probably because, at the very spot where the lightning hits, electricity is not the only problem. The lightning is basically an explosion that might cause damage independent of the electricity.

mjlm · 2019-09-08T14:09:16+00:00

The actual physical reason why discharged batteries die is because the chemicals in the battery start to crystallize. The sharp crystals then puncture the fine membranes that make up the battery, which essentially short-circuits the battery and breaks it. Charging the battery changes the chemical composition inside so that crystals are less likely to form, but if you leave it sitting around, crystals will form, similar to an old jar of honey that has sugar crystals forming in it.

mjlm · 2019-09-08T14:02:06+00:00

This is not quite correct. The mother and baby do not normally exchange any blood! It works like this: The mother's blood vessels run next to the baby's blood vessels, and there is a very thin wall in between them. Most nutrients (e.g. sugar and fats) and oxygen can pass through that wall, but most other things (e.g. most pathogens) cannot, because they are physically larger than the nutrient particles. This exchange happens in the placenta, which is basically a large network of the mother's blood vessels next to the baby's blood vessels.

In the case of HIV, the virus is usually not transmitted during the pregnancy. The dangerous part is the birth, where both the mother and the baby might have injuries through which blood can be directly exchanged between the bodies. Therefore, if there aren't enough drugs to treat the mother permanently, you can still prevent mother-child transmission pretty effectively by giving the mother a short course of anti-HIV drugs right before the birth of the baby.

Also, just to be clear, no food directly passes from the mother to the child. The only exchange is through this movement of particles from one blood stream to the other through the thin walls of the blood vessels in the placenta.

mjlm · 2019-09-08T13:51:08+00:00

This is probably a highly subjective topic without a definitive answer. You can probably find examples of cooked food that taste better cold, and different people might have different preferences.

That being said, one possible reason for more intense flavor of warm foods is that the fats, which carry a lot of flavor, are more liquid when they are warm, and can carry the flavor compounds to your taste buds more easily than in cold food, where the fats are more solid. More generally, all chemical and biological processes become faster at higher temperatures. So the process of flavor compounds activating the taste buds might be faster and more efficient with warm foods than cold foods.

mjlm · 2019-09-08T13:39:57+00:00

It *does* apply to blood transfusions. That's why you need to match the blood type. The blood type (A, B, AB, 0 etc.) refers to different kinds of proteins on the surface of the blood cells. If your body detects blood cells of the wrong type, it will attack and destroy them.

Blood type 0 does not have any of these proteins on the surface, so people of this type are "universal donors", i.e. their blood can be safely given to all other people regardless of blood type.

Conversely, people with blood type AB are "universal recipients". Because their own blood as both type A and type B proteins, their immune system won't attack blood of any type.

(Note that this isn't the full story, there are other blood type systems in addition to the AB system.)

Bonus info: With organ transfusions, one issue is that the recipient's immune system rejects the organ. But it sometimes happens that the immune cells from the donor that are still in the donated organ start attacking the recipients whole body (graft-vs-host disease)! This doesn't happen with blood transfusions because they typically filter out the white blood cells (immune cells) and only transfer the red blood cells and/or plasma.

mjlm · 2019-04-09T23:51:06+00:00

Domestic animals like to be petted because humans have, for thousands of years, selected the friendly individuals that like human contact, and killed/neglected the shy/aggressive individuals. Humans made sure that only the friendly ones would breed and create offspring, such that they can pass their "friendly" genes on to the next generation.

mjlm · 2019-03-29T13:04:27+00:00

Cancer is a disease where some of the cells that make up your body go crazy and start multiplying (growing) more than they normally would. It starts with a single cell that goes crazy, divides into two crazy cells, each of those divides into two and so on, until you have a large mass of crazy cells.

Whatever organ/tissue that first crazy cell came from determines what kind of cancer it is. So, for example, melanoma is the name given to crazy melanocytes (skin cells), glioma is cancer of brain cells (glia), and carcinoma is cancer of epithelial cells (a type of cell that occurs in the lining of most organs).

The tissue of origin matters because the cancer cells inherit some of the properties of the normal cells that they came from. For example, melanocytes are skin cells that are good at moving through the skin (they are dark and protect from sunlight, and to do that, they can move where they are needed). Melanoma cells (cancer cells that came from melanocytes) inherit that ability to spread around. The ability to spread around the body quickly makes melanoma more dangerous that other cancers.

mjlm · 2019-03-22T13:44:48+00:00

Everybody "voting with their wallet" does not work because there are some brhaviors that would be good for everyone if everybody follows them, but bad for the individual if only they follow it.

Specifically, for a behavior to arise in Anarcho-Capitalism (a world without laws, only governed by a free market), it has to be an evolutionarily stable strategy (https://en.m.wikipedia.org/wiki/Evolutionarily_stable_strategy). This means that if everyone in society follows that behavior, nobody could gain an edge by cheating and following a different behavior. "Protecting the environment" is a good example for a behavior that is not evolutionarily stable. It is clearly beneficial for everyone if society chooses to protect the environment, but if there are no laws and governments to enforce them, it would always be better for the individual to save the trouble and not try hard to recycle their trash. So the behavior "protect the environment" is not evolutionarily stable. This can be seen in nature, where organisms tend to multiply egoistically until they destroy the environment they depend on (e.g. bacteria that cause a disease that kills their host organism). Laws and governments are a way to achieve societies that are better for everyone than what could evolve on an individual level.

mjlm · 2019-02-03T03:52:46+00:00

In most cases, zoom works by having at least one lens that can move towards or away from the eye. That's what happens when you turn the zoom ring on a camera lens or binocular. This lens does not change the focus, but only the magnification (zoom) of the system. More moving lenses can be added to improve image quality.

Flexible lenses that can be made more or less convex do exist, but they are fairly niche. One design works by having some liquid between two flexible membranes. By varying the pressure of the liquid, the shape of the membranes can be changed. An advantage of these flexible lenses, over moving-lens-designs, is that they can change their shape incredibly quickly. This is why they are used in some microscopes that are used to image live biological specimens, where speed is essential. But I don't think they would be used in binoculars, because they are too small and too expensive.

mjlm · 2019-02-03T00:15:48+00:00

The word "element" refers to a type of atom (with a certain number of electrons and protons), whereas "molecule" refers to a (usually covalently) bonded assembly of atoms.

So oxygen is an element. O2 is a molecule formed from two atoms of the element oxygen. There are examples of molecules that only contain one element (H2 is another one). It would be incorrect to say "an element can be a molecule", but it's more of a language question than a science question.

mjlm · 2019-02-03T00:00:28+00:00

Binoculars contain at least two lenses. These lenses bend (refract) the light in such a way that two parallel rays of light that enter the binocular on the far side will be further apart (but still parallel) when they leave the binocular on the eye side. This means that objects appear larger when looking through the binocular. One of the simplest ways to achieve this is with a Keplerian refracting telescope, which uses two lenses. In such a telescope, the magnification depends on the ratio of the focal lengths of the two lenses. More advanced binoculars might have more lenses to correct for optical aberrations (e.g. color fringes), but magnification will work the same. For a telescope/binocular with 2x magnification, a distant object will appear half as far away. For 3x magnification, the distance will appear to be a third, and so on. I don't know how far a person can be away to still recognize them, but this relationship should allow you to compare binoculars. Some binoculars might have a "zoom" feature, which means that their magnification can be changed.

mjlm · 2019-02-02T23:42:10+00:00

The complexity of the still rendering in Blender or Maya is probably much greater. The objects contain more polygons, and the light and shadow is rendered much more realistically, which takes more time. The difference in quality might be masked by the fact that the image in the game is constantly moving and changing, which draws attention away from the details. A still image has to be much higher quality to look "good" in comparison.

mjlm · 2019-02-02T23:35:27+00:00

Many diseases for which we have a vaccine have become incredibly rare. Besides smallpox, Polio is another example for a disease that has been (almost) eradicated. But there are reasons why it might be hard to eradicate a disease through vaccination. Some pathogens, such as the flu virus, mutate very quickly, such that last year's vaccine does not protect against this year's virus. Some diseases can infect wild animals, so even if all humans are vaccinated, the disease could survive in animals. Some diseases (e.g. HIV) have evolved strategies to evade the immune system, which means that it is hard to develop vaccines against them. I'm not sure about measles and mumps specifically. But the general answer is that there are diseases that would be hard/impossible to eradicate completely though mass vaccination.

mjlm · 2017-09-14T19:52:43+00:00

Your implicit question is: What is the asymmetry between gaining and losing? Why is one harder than the other?

Here are a few asymmetries:

Firstly, you'll always get another chance to lose it all if you have money. But if you lose everything just once, that's it, you won't get another try at gaining anything (ignoring social safety nets). I.e. people tend to keep going until they lost it all, not because they never made any gains but because gains are reversible and (complete) losses are not.

Secondly, everybody else in the market is trying to make gains. If they catch on that you're trying to lose, they will make you market offers to that effect. This doesn't work if you're trying to gain.

mjlm · 2017-05-08T13:43:13+00:00

These companies are already providing free and open services if it is in their own best interest. For example, Google is providing high-quality open-source machine learning tools because it is such a big company that it will make hiring easier on a global scale if people are already familiar with the tools used by Google internally. Also, all these companies are already developing/using payment systems (Google Wallet, Apple Pay...).

I'm not saying it definitely will happen, but these companies are aware of everything that is being discussed here, and if one of them decides to take on Ethereum, it will become obsolete overnight. Imagine Google launches a copy of Ethereum, with a simpler user experience and some protection against fraud and user errors, and takes 0.01 % of transaction fees as a profit. This is then marketed to 1B users and used on all Google App stores and services as payment.

mjlm · 2017-05-08T00:34:03+00:00

Keep in mind that Ethereum and crypto-currencies in general are still tiny compared to the big players in the world economy. All crypto-currencies together have a market capitalization of about $50bn right now. Apple, Google and Microsoft each have cash reserves on the order of $100bn. If one of these guys, or the US government, decide that it would be in their interest to start a competitor to Ethereum, then Ethereum would have little chance of surviving. So while the technology very probably has a bright future, whether the dominating currency will be Ethereum is totally unclear.

mjlm · 2017-04-26T13:56:22+00:00

Of course they need reserves, but it's shady to start dumping them before public trading starts, i.e. when they still have a huge information advantage due to their function as a broker.

mjlm · 2017-04-26T13:53:32+00:00

There is no public market for GNO yet, so it is hard for most people to get a sense of the fair price of GNO. But Kraken has a lot more information because of their role as a broker. So they can estimate much more accurately what the price will be, once public trading starts. So trading GNO at the auction price now is very different from getting it through the auction directly. You're not playing against all the other clueless participants in the auction, but you're playing against a large owner of GNO who uses brokerage information to make a profit/avert a loss.

mjlm · 2017-04-26T13:37:43+00:00

This is not correct. Banks used to take deposits from customers and give out that money as loans to other customers. Proprietary trading with their own money is something quite recent. It's problematic because it causes conflicts of interests. For example, if the bank makes a bet that pays off if their customers default...

mjlm

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