Recent comments in /f/explainlikeimfive

tacogamer20 t1_j27o7fu wrote

The link between Alzheimer's and amyloid plaques has fallen out of favor the last decade or so. Tau tangles, for example, have been linked to Alzheimer's like symptoms. There have also been many cases where plaques are present without symptoms, and symptoms present without plaques as seen after autopsy.

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FriendlyCraig t1_j27nv0i wrote

Latex can be harvested directly from trees, and still is, but most plastics used today are from petroleum.

Simply put, plastics are chains of carbon+other stuff. Petroleum is very rich in carbon+other stuff. Refineries break down big chains of petroleum into smaller parts. They then combine these smaller parts into other big chains, which are the various types of plastic we use today. The same can be done with natural latex, but that stuff isn't as abundant so we don't use it much anymore.

An analogy of this would be starting with a house. You break down the house into smaller parts: wood, nails, drywall, paint, and so on. You then use these parts to build a bunch of sheds.

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Harrison_Phera t1_j27mh3p wrote

All rectangles are squares, but not all squares are rectangles.

Dementia is a condition that causes memory loss. Alzheimer’s is a type of dementia. Just like a square can have 100’s of different sizes, one being a rectangle. There are many types of dementia, just one of them is Alzheimer’s.

Alzheimer’s is the rectangle.

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greenknight884 t1_j27m8q0 wrote

We classify dementia by the patterns we see in affected brain tissue under the microscope. Amyloid plaques and tau tangles -> Alzheimer's. Lewy bodies -> Lewy body dementia. Pick bodies -> frontotemporal dementia. It's more complex but these are examples of elements that help make a tissue diagnosis.

Since most people don't undergo brain biopsies while alive, the best we can do in a living patient is make an educated guess based on symptoms, and sometimes supplement with specialized imaging and spinal fluid tests.

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Firefrorefiddle t1_j27lerp wrote

To add to the comments that are already here, professional dancers go through pointe shoes extremely quickly (often in a matter of days or weeks depending on things like their role, the rehearsal schedule, and the performance season). Pointe shoes have to be easily manufactured on a wider scale so that they can be available for any dancer to pick up a new pair at a moment's notice (with caveats for things like vamp style (think "toe cleavage"), box length, etc.). It's much faster to make several copies of a "standard" style than for a ballet dancer or their company to order, say, 10 pairs of their custom-made shoe and risk running out before opening night - or risk a shipment being delayed and not having any shoes at all.

(Some dancers definitely do that, though, depending on their status and sponsorship opportunities.)

Since pointe shoes are mostly paste, cardboard, and satin, it also allows for the shoe to evolve around the foot as the dancer's body changes. Imagine if you had a bunion, and your custom shoe no longer fit around it: you'd likely have to get your foot re-measured, with no guarantee that the bunion would stay the same size. Or what if one of your feet is arched a bit lower than the other, and needs a thinner shank (the hard part that supports the arch of the foot)? It would be easier to modify the shank of a standard pair of pointe shoes than to go through several iterations with a maker.

Some dancers prefer "soft" shoes, which is where you'll see the B-roll of dancers banging their shoes on concrete. ("Soft" makes it easer to feel the floor against your toes and makes the foot look more sleek, but often comes at the cost of foot support for sustained, slow movements.) Hot tip: you can microwave your shoe to achieve the same effect on a less localized level! Some dancers who have low arches often also want to break the shank so that the arch of the foot is more pronounced. (You can do this by applying water to the shank in a thin line and bending it. It's very contentious on which way to bend it, though.) Scraping the point / top of the shoe box with a razor or sandpaper is just a way to reduce slippage by adding friction (either by taking the satin off of the tip entirely or just by roughing it up). That depends on what kind of floor you're dancing on - for instance, wood is really slippery, but vinyl Marley floors offer a lot more traction.

tl;dr: pointe shoes are an extremely specialized tool that depend heavily on a person's body and situation, which are always in flux, and any custom-made item is going to be "frozen" at a point(e) in time that may not be compatible with a dancer's body or situation on any given day. Also, standardized shoes cost way less!

Source: semi-professional ballet dancer (18 years)

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quirky_yolo1 t1_j27klkq wrote

Dementia refers to a problem with thinking skills like remembering, paying attention, multi-tasking that is bad enough that it makes it hard to do everyday activities like having a conversation, preparing a meal, planning your day, or doing chores.

Dementia can be fixed (reversed) if it is caused by an infection (like syphilis) or a poisoning (like overdose of bismuth from taking too much pepto-bismal) but in most cases it is not.

The top three most common causes are

  1. Alzheimer's disease
  2. Vascular
  3. Lewy body (which includes dementia with Lewy bodies or Parkinson's disease dementia)

The diagnosis of dementia is made by a clinician (such as doctor or nurse practitioner) by getting the whole story and completing the necessary tests (this may include testing by a neuropsychologist.) Doctors and other clinicians who diagnose and treat dementia regularly (for example neurologists, geriatric medicine specialists, or geriatric psychiatrists) will use a combination of the history, neurological exam, brain scans, blood tests, and the neuropsychological test results to diagnose the cause of dementia based on standard criteria.

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Triabolical_ t1_j27ivjd wrote

To oversimplify...

In studies you are looking for what is known as statistical significance, which is basically shorthand for it being very likely that the effect you are seeing is a real effect rather than just being an unlikely chance effect.

If you are looking at the effects of a drug, perhaps the effect that you are seeing is just random chance - the people who took the drug just randomly got lucky and the people who didn't take the drug got unlucky.

So you do replication to rule out that chance. If you do two independent drug trials and they both show the same effect, the chance that it is due to random fluctuations is much smaller.

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Triabolical_ t1_j27hw5e wrote

The other answers are good but are missing some nuance.

The difference between compiled and interpreted is when the translation operation is done. In compiled languages, the translation is done all at once before the code is shipped, and in interpreted languages, it is done when it is run.

There are hybrid approaches, however.

C# is a compiled language, but it's not compiled to machine code - it's compiled to an intermediate language known as ".NET intermediate language" or ".NET IL". That code is then compiled into machine code on the user's machine, but it's done in small chunks using what's known as a "just in time" compiler, or JIT. Except some code that will get used all the time gets compiled into machine code once to avoid the overhead of doing it all the time.

There are other approaches that compile the language to an intermediate language called "p code", and that p code is interpreted when it is executed.

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