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right except for the reverse situation. though it is a more-or-less passive process, the rod/cone pigments are constantly regenerating at the same rate regardless of light level.

when you go into a dark room, the cones are stocked with pigment but it's useless - but it will take a few minutes for the rods to be fully stocked, since they were bleached by your earlier exposure to light.

when you step from darkness to light, there is a brief flash since suddenly all your rods pigments are isomerizing, but the cones are functioning from the get-go.

So if I understand you correctly, when suddenly going from a bright to dark environment or vice versa, the adjustment period is caused by our rods and cones adjusting the rate of photopigment production to return the photopigment to ideal operational quantities.

So when we go into a dark room, there aren't enough photopigments to catch what little light enters our eye and no signal gets sent to our brain and we're effectively blind until the photopigments get to high enough levels to detect the low light.

And in the reverse situation, there's too much photopigment so all our light cells are blaring/bleached and we're again blinded until the photopigment levels drop.

Is that right?

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Clones isn’t quite the right word. The grafted branches are clones but the apple’s or at least their seeds are a genetic scramble.

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The pupil's contribution to light adaptation is relatively minor.

The main action is in the retina. There are two types of photoreceptors in the retina, rods and cones. They work in similar ways: they are constantly producing substances called photopigments, and when the right kind of light hits a photopigment it transforms in such a way that it can activate the photoreceptor so that it sends a "light detected" signal.

Rods are extremely sensitive. A rod can potentially detect a single photon. So, you use your rods to see in very very low light conditions. But because of this great sensitivity, a moderate amount of light will 'bleach' the rods, destroying their photopigments and making them useless.

Cones are very insensitive. It takes hundreds or thousands of photons to trigger a cone. But this is fine, because most of the time you are in environments that are totally flooded with light, so there's almost always enough to trigger your cone detectors.

Since they are so insensitive, it's just about impossible to bleach the cones (a very bright flash, or glancing at direct sunlight can do it). So, they are always producing pigment that is available to detect photons and excite the cones.

Both systems are very homeostatic in their light regimes, producing pigment in decent amounts so that available light can be detected, without ever needing to know the current light levels. Luckily they overlap in their sensitivities, so there's no light level at which you have no functioning receptors.

Basically, long story short, when it's very dark your rods become useful because they're so sensitive to light and your cones become useless because they're so insensitive. When it's not very dark, your rods are bleached and useless, while your cones are now useful because there are enough photons to stimulate them.

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Apples are done this way because they are not true to seed, meaning you won't get the same type of apple as the parents were. Doesn't really answer the question, but growing an apple by seed could get you one of something like 40,000 different apples, most of which are not good to eat. If not familiar, look up Johnny Appleseed for an interesting story.

Not a complete answer, however- if some cells are more damaged by the sunburn, they might get replaced faster

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This. Also it would help a lot to know when the dose was taken. Lots of things once they've entered the blood stream are metabolized with sort of a half life. For caffeine, for example, it's about 5.5 hours. If someone has 100mg of caffeine in their system it could be because of the cup of tea they had in the last hour, or the cup of coffee they had six hours ago.

This is a bit confusing and there's a lot of incorrect information out there.

The aerobic system - which gives you power for low-intensity efforts - is dual-fuel. There is a pathway where it can be fueled by glucose (glycolysis/pyruvate oxidation) and another one where it can be fueled by fatty acids (beta oxidation). Both of those paths feed into what is known variously as the Krebs cycle or the TCA cycle.

The obvious question is how the body determines whether to burn fat or glucose. It's a bit complicated.

If your blood glucose is elevated from carb intake, your body will preferentially burn glucose to try to get the blood glucose to go back down.

If blood glucose is normal, then the body will burn glucose and fat based on the kind of training you have done. Mostly high carb training, you will burn glucose. Mostly low-carb training, you will burn more fat.

At higher intensities, the additional power only comes from glucose. So a highly-trained aerobic system is better for burning fat.

So, if you want to burn a lot of fat, you need to train your body with extended periods of zone 2 training without much glucose around. Fasted is the best, but you need to transition gradually or you can run out of glucose ("bonk"), which is no fun.

This also means that the idea that you should "eat carbs to fuel your workout" is bad advice for those who want to lose weight.

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That video was really cool. I knew ice expansion was strong but I didn't know it took so little. And the remaining water interacting with the LN2 was awesome too

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As a vet, the question of “why aren’t human medications doses based on weight” has always baffled me! We dose nearly everything in mg/kg because patient sizes are so different. We have some rules of thumb for species with a fairly standard size (mg/cat is a common one!) but I typically double check the mg/kg dose anyway.

Good to know. Thanks for the info.

It’s important to remember that many studies are funded by private sources (often companies) whose lines of business create a conflict of interest.

“Here is US $15M to study whether Vitamin D does (x or y).”

“Aren’t you from the supplement industry?”

“Hush! Take the money and do an objective, unbiased investigation. If you find what we want, there’s more funding where that came from…”

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