If bananas reflected yellow light, but we saw them as blue instead by some purely neuropsychological phenomenon, would this cause any significant problems?
That's actually a question of qualia and as long as you see the same frequency or collection of frequencies as the same color consistently, you can swap them around arbitrarily, but if you can't tell the difference between, for example, red and green, that is a real disadvantage.
Is that true? Yellow/Orange/Red are perceived as 'danger' colors. Is that just a made up association in our brains, or do we see yellow/orange/red more readily? If you flashed a bright orange billboard in front of a chimpanzee, would you get a different reaction than if you flashed one that was dark blue?
Orange and dark blue are names we give to perceived frequencies of light.
Dark blue isn't really any 'darker' in terms of energy content spectrum than orange is, its our brains that have evolved to make this association that X spectrum is dark and Y spectrum is bright.
The most terrifying thing about prions is that they are infectious but not alive: they can't be "killed" in the normal sense by sterilization. The proteins must literally be dissolved to neutralize them.
When I was a teen I was so freaked out by this fact during the mad cow episode in England that I never ate beef since. I would not for a few years even eat anything prepared in close proximity to where beef was being prepared.
I lived in the Caribbean at the time...
The risk with beef was always pretty low. Actually not eating beef and eating an alternative meat is probably riskier given the prevelance of salmonella and other nasty bacteria in chicken.
If you are specifically (and erroneously) terrified of catching a prion disease, chicken is still better. You're much more likely to get sick but much less likely to catch a prion disease.
Which has to be the leading contender for our civilization's equivalent to "those Roman Empire folks were so dumb for using lead, ha ha". Though it is highly doubtful that lead poisoning caused the downfall of the Roman Empire, one to two order of magnitude elevated levels of exposures compared to normal background levels were no picnic the bodies of for those exposed.
Another example of distributed costs, concentrated benefits really screwing us over in the long-run.
I thought that the spooky thing about prion-based diseases like CJD is that symptoms can take a long time to appear after exposure. (Although, on reflection, I can't justify this, and quick googling does not turn anything up.) The onset of death after first symptoms is relatively quick (a few months to a year).
The point being, that we may not be able to measure risk at this time, because the prions may be latent in people. (Cue spooky music.)
I lived in Germany in the 80's when my dad was stationed there as part of the military. I am barred from giving blood in the United States, as are many military men and women who served during that time, because of this [1]. This is especially sad because many active and former military personnel, and their families, take blood donation very seriously.
I was raised to do it, but I am now barred due to the note on the eligibility sheets. I talked to a Red Cross area administrator about it and he said that, even though it has been over 20 years, they are unlikely to lift the ban until effective testing and treatments are found. Since there are no tests, they can't risk the blood supply.
Back when the UK banned butchers from selling beef on the bone, my mother was still buying it "under the counter". Her argument was always- if it's here then we've already got it.
And it makes them incredibly hard to fight. We basically have two ways of dealing with them:
• Use vaccination to train the host's immune system deal with it, should it ever encounter the full version.
• Use special drugs to slow down their replication to let the host's immune system deal with the rest.
Prions have no special, prion-only replication strategy we can target, and I'm not sure whether the immune system can be trained to attack only prions and not their regular protein equivalents.
I think you underestimate the immune system. We automatically remoce thousands of misfolded proteins every second in our cells. Its just those few the cellular defence has not yet adapted to too much that we notice. Some kinds of vaccination might work (like expressing part of the misfolded protein to make it an antigen) etc. The reason why we do not have any medication against prions is because they have never been a big thread to us. Pretty much like asteroids, if they fell on us regulary, we would build a planetary defense. But for now, that not up on the agenda
>and I'm not sure whether the immune system can be trained to attack only prions and not their regular protein equivalents.
A prion tends to be vastly different than the original protein. I thought the bigger problem was that prions are the metaphorical tanks of the protein world. Just look at what it takes to denature a prion compared to other proteins.
Of the 6 or 7 criteria biologists usually use to define life, viruses often fall short. E.g. viruses do not have their own metabolism.
Everyone has their own definition though. I remember reading a novel where life was defined simply as heredity, mutation, and adaptation. The second definition makes more sense to me, and implicitly includes viruses.
Spores formed by bacteria like C. botulinum or B. anthracis are also very difficult to neutralize. The key is knowing if there is an exposure risk and taking added precautions.
The good news is that some people are "immune" to developing an infectious prion disease. Turns out that certain mutations prevent normal proteins from interacting with a complementary prion in a way that would cause them to become misfolded.
So for people with Alzheimer's disease, is that plaque always associated with prions/protein mis-folding? (and if so, is it worthless to do things like "Learn a second language," "Learn to play more instruments," etc because our brain usage doesn't really play into the development of Alzheimer's? It's mostly a genetic thing?
It's an unsatisfying answer, but Alzheimer's (and most disease for that matter) is a combination of genetic risk and what you do with your life. It is hard to know exactly how much genes or the environment contribute. There are subsets of neurodegenerative diseases that are almost entirely genetic (Huntington's, some forms of Parkinson's, etc.) and some that are almost 100% environmental (there's an interesting story about a group of IV drug users in San Francisco who developed Parkinson's after taking something laced with MPTP). Most cases are somewhere in the middle though.
Learning other languages or instruments is probably useful from a brain health standpoint regardless of your genetics (even if you already have early-stage AD you can slow progression), but they are just proxies for activity. I would guess that learning something that interests you is more important than what that thing actually is.
I guess it's more complicated than that. Brain usage affects its chemistry - how much of what is available where - which, in turn, may have an effect on how misfolded proteins interact with normal ones.
Keep in mind I'm no expert, but this seems to be a reasonable assumption.
Yes, it can not be "killed" but, as other dangerous/infectious particles (like viruses), it can be destroyed. The immune system is able to naturally develop defenses against both live and inert foreign bodies, but only if the given body is over a certain size. The small objects (relative to cell size) do not trigger antibody creation and that is why this abnormally folded protein is so dangerous. There are, however, methods in which the organism is trained to recognize and develop natural defenses against bodies as small as a molecule, say, to prevent relapse in drug addicts:
This method may be a little bit costly (relative to promised returns of solving a problem that does not directly affect humans) and with limited effect, but still, it may be a way worth investigating.
Viruses have two main components. The first is the delivery package. This is the element that is capable of delivering a payload into the interior of a cell. The second is the genetic code that hijacks a cell's normal functioning to produce more viruses. Viruses have a genetic component, either RNA or DNA, which contain instructions for building their viral envelopes. The genetic material is as vulnerable to damage as cellular DNA.
Prions are a single component. They are proteins with the same amino acid sequence as a protein normally produced by an organism. Except they have been misfolded. The geometry of the misfolded protein is such that it becomes a catalyst to reproduce the same misfolding error. There are no "brains" in them. They can arise entirely accidentally. They're a bit like the ice-nine from Vonnegut's _Cat's Cradle_, in which a crystal of a novel form of solid water that melts at a higher temperature can recruit liquid water to grow the crystal without limit. Each individual prion can misfold any number of same-sequenced amino acid chains.
And like the ice-nine, which melted at a temperature above human body temperature, the prion may be able to survive through more extreme conditions than other forms of the protein.
In the best case scenario, the prion does little more than cause a deficiency of the normally-folded protein forms in the body. In the worst-case scenario, it poisons some other process within the body in its misfolded form.
Pet peeve of mine, but it looks like you slept through English class as well. The plural of "virus" in English is "viruses". "virus" in latin is a mass word and has no plural, like "sugar" and "air".
Your perscriptivism here seems misguided then, because if virus is a mass word we shouldn't be saying viruses either: just "virus". And anyway, if we absolutely had to express a plurality of virus, it would be "vira".
Anyway, this is hackernews.
For those of us who grew up in internet hacking communities of the early 90's "virii" was the plural form in the lingua franca. As a descriptivist of great habit, I will continue to use that form.
I am actually a descriptivist myself, but the prescriptive approach usually works best when trying to convince people how to write. Apparently not so in this case.
How about this argument then: "virii" is f*ckin ugly? No? Darn. :-)
Just because a noun is a mass word in one language, it doesn't mean it has to be in other languages that have borrowed the word.
For example, in my language, "lego" is a mass word, and to make a plural you would have to say something like "pieces of lego", but in English, the plural of "lego" is "legos".
My understanding is that the fact that viruses are not alive is more of a convention, similar to Pluto not being a planet. This is more of a question than a statement, I would love it if somebody with some knowledge on the matter could chime in.
life, species, organism.... all are leaky abstractions.
[There's a "species" that spread around the Andes and eventually reached itself on the other side---and could no longer breeed with "itself". Genes could still in theory travel all the way around and back to the discontinuous point, however.]
Having thought about this a lot, the best definition of life I've been able to come up with is as follows:
An object is considered to be alive if it consumes energy to create or maintain its own order (in opposition to the general effect of the second law of thermodynamics in the wider system in which it finds itself).
Bacteria can do things on their own (say, swim in water). Viruses can't do anything without a host's reproduction engine (like a program which can't do anything without a computer to run on). Prions are misshapen proteins which tend to damage other proteins such that the result is the same misshapen, and thus duplicating, form.
I think what was meant is that on the grand scale of "aliveness" viruses are more alive than prions. Viruses have DNA, they actively seek out host cells to hijack so they can reproduce, etc. Prions are much simpler and aren't alive at all. They're just accidentally self-reproducing patterns, basically. They don't have DNA, they don't make any specific effort to reproduce, they just "happen" from weirdly broken matter bumping together.
Are you sure we are talking about the same "functional programming"? Consider a function that parses a number from a string, and a function that doubles a number. How could anybody expect the order of these applications to not matter?
Some people just oversell it, or don't think of the whole spectrum of commutativeness scenarios when they write about FP. I give several examples of that, lower in this thread, with links.
And it's exactly the same thing that the author of the original article discusses -- that order was supposed not to matter, but it does.
I don't think anybody ever meant to imply that pure functions can be composed in any order. That's the confusion here. "Pure functions can be run in any order" only means that they don't have side effects so one call doesn't impact another, but nobody ever meant or (hopefully) understood that to mean that the inputs and outputs of pure functions could be composed in any order. I don't even know what kind of confusion could lead to such an idea.
When reading anything on The Guardian it's important to ask what they aren't telling you, because it's almost certain that they are omitting many very salient details out in order to fit the story into their own narrative. If you knew that Nieto had other problems, you likely wouldn't come away from the Guardian article believing that he was executed for being Hispanic.
The Guardian and Salon are two of the worst offenders. I learned a little while ago that Sam Harris took on Salon. I always thought Sam Harris was a blowhard and annoying to listen to, but I have a lot of respect for him now. We need more honest, courageous intellectuals to take on the fourth estate.
People in third world nations don't have any empathy super powers for people who are ethnically, religiously, or socio-economically from themselves either.
Indeed. Somehow I don't think the commentator is a supporter of the Black Panthers, who I think were the last US political group trying to prevent their members being killed by "the government".
