This great page shows factors affecting central venous pressure.

It isn't the arterial vasoconstriction that affects preload, but venous vasoconstriction, that would also occur in the compensation by sympathetic factors (such as circulating adrenaline).

As the other answers say, it is because they are using superconductive magnets.

When a superconductive material is cooled below its critical temperature (different for each substance and we'll ignore magnetic field limits) ALL electrical resistance is removed.

Above this critical temperature the material may have a low, but finite resistance. Given the amount of current required to create the high magnetic fields even a very small resistance will result the release of a considerable amount of heat energy--very likely resulting in significant damage.

MRI machines make use of superconductive magnets to generate huge magnetic fields as well. If even a small part of the superconducting magnet is heated above the critical temperature a magnetic quench can occur. The high current will greatly heat this section leading to larger areas being exposed to higher than critical temperature with them going non-superconducting, and so on. This is very bad. The machines are built with safe guards to shut down the machine as quickly as possible, but there'll be some very loud noises and potential damage.

So fusion basically uses gravity to turn mass into energy?

Funny enough cows pregnancy last for about 9 months. Followed by aboht 10 months to a year kf milking period and then the dry period. How many cycles deoends on how healthy the cow is but they should last for about 10 years before they are too old.

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I'd assume that diatomic hydrogen having more energy than a helium atom is discounting the mass energy of the neutrons...

To help you understand exactly what happens, you need 4 hydrogens to smash together with tremendous energy, typically due a massive amount of gravity pulling them together.

Each hydrogen atom has 1 proton, but when you smash 4 of them together 2 of the protons "morph" into neutrons. Neutrons are slightly more massive than protons, so all things being equal you can understand why 1 helium should have slightly more mass than 4 hydrogens.

What's also happening is part of that energy in the first place that fused the hydrogens in helium got "solidified" into mass of helium, like energy gets stored in a battery. That energy can be pulled back out if you get the helium atom to decay, this is literally how nuclear energy and nuclear bombs work.

Not sure where you are getting the "more energy" bit from. Either you're thinking about how we can use hydrogen as fuel and not helium (which comes down to electron configurations, hydrogen is "unhappy" and that unhappiness creates a desire to participate in chemistry, hence boom.) Or your thinking of the original energy required to fuse the hydrogens in the first place, and that usually comes from gravity.

And the two hydrogens (now a molecule) have more energy because of the intermolecular forces - as the hydrogens oscillate (kind of) their movement towards and away from one another is more energetic than the helium atom just on its own.

Edit: there is a quantum chemistry exercise in calculating the variations in energy between a hydrogen 2+ molecule (two protons sharing an electron) and 3D mapping the changes. It was much more difficult without the internet and digital graphing available nowdays.

If you’re asking about nuclear fusion, the process actually begins with four hydrogen atoms, two of which end up converted to neutrons during the reaction.

Two electrons and two positrons are ejected and then annihilated along the way, releasing a considerable amount of energy.

You’re correct but what I was asking/confused about in the post was about your first paragraph. I had trouble understanding how the vasoconstriction increases/keepsConstant preload (before getting overwhelmed)

It’s true that preload & BP ultimately decreases due to overwhelming blood loss, I just couldn’t comprehend the first part about how the body tries to maintain/increase the initial drop before the overwhelming fall

Your reply is immensely insightful and much appreciated!!

Publicly funded research is freely accessible in most countries. The US is just not one of those countries.

Hint: You can always get an abstract of the research paper, which identifies the author(s). Contact the author(s), and they will almost always provide you the researchpaper for free. (They are allowed to do this.)

Two hydrogen atoms have less mass than one helium atom because helium atoms have neutrons in addition to protons while hydrogen atoms just have protons.

it's a sloppy shorthand, fine as a joke but not an explanation

I am from India and always have between cows and buffaloes. Remember, my description of dairy will be different from Industrial dairy.

So, we used to have 4 to 5 cows. Whenever a cow gives birth, we will always feed the baby first. New born babies get almost half of milk and rest will be used by family. As the calf gets older like 3 months, the milk consumption decreases and he will eat food such as grass and feed.

after some time they grow old enough to completely feed off the grass. this is when family can use all the milk. Cow will keep giving milk up until 2 years on average and they may become pregnant. However, the quantity will keep decreasing overtime and fat percentage will increase.

Cows start the milk process for the first time when they give birth.

Plus stuff like sneezing, coughing, and diarrhea are useful for getting new bacteria and viruses out of the body and into another host. So germs that cause those kinds of reactions have a selective advantage.

Fun note with structural colour: our eyes don't have any blue pigment, but we do have blue structural colour.

Not sure about the energy point. I assume you mean when attaching to oxygen to make water?

Mass though, it has to do with the amount of neutrones. Helium needs more neutrons to stabilize itself thus adding more weight to it. Normal Helium also can not for bonds meaning it doesn’t react thus can’t produce or take energy because it’s electron ring is full of electrons. No pressure to fill the ring with bonding to another element

I have it like this:

There is bleeding. At a certain point, blood pressure measured in the aortic arch and carotid body baroreceptors drops. The body compensates by triggering a release of circulating adrenaline as well as noradrenaline signaling to the sinus node. This will briefly increase contractility of the heart and heart rate, as well as induce peripheral vasoconstriction through signaling at alpha receptors.

All this would serve to compensate for blood pressure loss that goes with blood loss. So if I have that right, in this initial stage of bleeding blood pressure and venous return (preload) could be kept relatively constant by this compensation mechanism.

Over time, the bleeding overwhelms this compensation mechanism, and as intravascular volume drops, blood pressure drops and central venous pressure drops.

At no point, I think, will any of these parameters be significantly increased over baseline: blood pressure and venous return will be compensated (equal) at best, initially, before dropping.

You're right - the only animals that produce milk are mothers. But generally, in mass producing dairy farms, the cows don't get pregnant naturally. The mothers get artificially inseminated, get pregnant, give birth to their young, the young are stolen from her and reared for beef or dairy or killed if no use, leaving her in a continual state of distress and grief, usually chained to bars and pumped for milk before the artificial insemination process starts again so she can produce more milk. The reason for the abundance of dairy products is because of this wide-scale non-surrendering abuse. Dairy farmers on a smaller scale may proclaim she's in a more habitable environment and any other line to make you feel it's more ethical, but the cows mostly all end up the same way... and in any case, 100% of the produce you get from shops and supermarkets that you refer to are attained from the mass-producing dairy farms. If you want further information "Earthling Ed" is a great educator on YouTube.

Well you got me remembering now.

I think we used "X-dot" (X with a tittle) specifically for velocity as x represented physical distance/displacement and X-dot-dot for acceleration.

It doesn't seem unreasonable that we could have used the notation differently as well. There's no fundamental reason why a prime has to be a space derivative and a tittle a time derivative. It might make communication a little tricky at first, but the meaning should be made clear by context (and if it isn't, we probably would want to use more specific notation anyway).

That’s what had me confused, this is what I was able to understand. Circulating blood volume does indeed decrease hence blood pressure drops hence preload is decreased. the body apparently reacts to this by undergoing vasoconstriction which pushes/squeezes the red blood cells forward to the heart (blood pressure isn’t sufficient so vasoconstriction is like an additional booster to help “maintain” things) thus the blood pressure increases as the heart has just received blood (that wasn’t able to make it back before vasoconstriction) and preload increases as again heart has just received blood.

Now of course by saying “blood pressure increases” & “preload increases” it’s definitely a minuscule amount and the rate of increase is still far below than average and not enough to suffice for the body

I could be misremembering... this was quite a bit ago.

>From ... Newton we get the y' and x' notation which (In my engineering school at least) specifically refers to time-based derivates.

Interesting! We used a prime for spatial derivatives and a tittle for time derivatives in my physics education when we used Newtonian notation.

> And you butcher them young because the beef isn't very good from adult dairy cows.

Dairy breeds are used as beef cattle too. The meat is just as good if they're slaughtered at 18 months like usual. It's just that many retired dairy cows are 10+ years old so their meat is tough.

But it's easier to sell male dairy calves to be veal than to bottle-feed them long enough to go on pasture.