fastspinecho t1_jd9ioe5 wrote

Yes, the rest of the body could still function.

That said, it probably wouldn't function for that long. The brain has "autonomic" functions that help maintain proper blood pressure, etc. After it's gone, the body will eventually become hemodynamically unstable and cardiac failure is pretty much inevitable. I suppose some future medical advances might one day prevent that. But really, why bother?

In practice, brain death is legal death. Hospitals will not provide life support to a dead person, unless they are an organ donor. So once brain death is diagnosed, one way or another that person will soon be in the morgue.


fastspinecho t1_jd8ckeq wrote

First of all, there are two clinical definitions of death. The traditional definition is irreversible loss of blood circulation. The heart doesn't "decide" to do this, but due to some injury it can no longer pump blood. This means it can no longer deliver oxygen to the rest of the body, which means most of your organs can no longer produce sufficient energy to maintain homeostasis. Among other things, cells need to constantly use energy to pump water out of themselves. Without energy, they usually swell up and rupture. Again, this is not a "decision" or signal sent to the body, any more than a balloon decides to pop when punctured by a needle.

The second definition of death is "brain death". This means that brain cells are no longer receiving blood, and are all dying for the reasons given above. Other organs may still be receiving blood, but legally the person is still dead.


fastspinecho t1_j9vy7o2 wrote

Scientifically, it's valid. But IRBs are less tolerant than ever when it comes to unnecessary harm to volunteers. And sham surgery usually means unnecessary harm to volunteers.


fastspinecho t1_j9ufxh4 wrote

A randomized controlled trial is usually better than the alternatives, even if it is not blinded. And non-blinded RCTs are performed all the time, for example for new surgical treatments (nowadays sham surgery is frowned upon!)


fastspinecho t1_j9st4zm wrote

You have two lungs, two liver lobes, two parotid glands, two thyroid lobes, two eyes, two ears, two arms, two thumbs, two legs, two cerebral hemispheres, two gonads, two breasts, etc.

Sometimes the "doubled" organs are so close together that they are considered one (liver, thyroid, brain ...). But that's just developmental happenstance. In some people, the left and right kidneys are combined into one giant "horseshoe" kidney.


fastspinecho t1_j9qx65q wrote

No, the first-generation satellites weigh only 250 kg.

SpaceX eventually plans to put second-generation satellites into orbit, which do weigh ~1200 kg. However, they will need fewer of them, because they are more powerful than the first-generation satellites. They are not currently capable of putting many of these into orbit, and only have permission to launch 7500 of them in the future.

Spacex ultimately plans for the first-generation satellites to constitute 75% of its fleet.


fastspinecho t1_j9q9gwm wrote

They aren't planning to use 42,000 Starlink 2 satellites.

The current plan is to deploy 10K to 30K satellites. They don't think they will actually need 40K.

Furthermore, the majority of their satellites are first generation, which weigh only 250 kg. They are only authorized to launch 7000 Starlink 2s. Starlink 2 satellites are more capable, so every Starlink 2 they launch will reduce the total number needed.

SpaceX launches 10 or so Falcon 9s a month. Each one can carry 60 of the smaller satellites, but only a handful of the Starlink 2. I don't think it's feasible for them to launch an average of 23 Starlink 2 satellites a day, even after switching to their bigger Starship rocket. And what comes down must go up.


fastspinecho t1_j213rno wrote

> Medical error is estimated to be the 3rd leading cause of death in the US leading to 250,000 deaths each year.

This is a highly controversial article. Among other things, it considers any intervention that leads to patient death an "error".

In other words, suppose you have an advanced brain tumor. Without treatment, you will die in 6 months. Your surgeon offers an operation that can cure you, but has a 10% mortality risk. You accept the risk.

According to that paper, if you die on the operating table then your death will be counted among the 250000 "deaths by medical error". To avoid errors, surgeons should not operate at all on high risk patients.

I don't think most people would equate known risk with medical error. And that's the only way the authors end up with such a high figure.


fastspinecho t1_ivhyypy wrote

> evolution is a larger pheromon, not applicable to the minute scale of individuals. Yes, individuals do change, but for those changes to actually be evolution takes many gerations.

You mean like when I wrote that evolution "is manifested in the differences between an individual and its ancestors"? What do you suppose "ancestors" means?

All your arguments have been aimed at a straw man.


fastspinecho t1_ivgi3b0 wrote

> still not citing anything.

I cited the first paragraph of your linked article.

> The main difference between evolution and speciation

So, they are related concepts but not the same. Like I wrote earlier.

> individuals do not evolve

If you mean that a single individual cannot evolve over the course of its lifespan, then I'm glad you agree with what I literally wrote earlier.

If you mean individualS - plural - cannot evolve, then you are wrong. A group of individuals can evolve, even if the rest of the species does not. Which is why I wrote "evolution acts on individualS, not species". And why I didn't write "evolution acts on an individual".


fastspinecho t1_ivgdije wrote

I read both sources, and I found nothing to support the contention that "successful evolution caters to the whole species with little regard for the individual".

Quite the opposite in fact. Evolution always begins at the level of individuals, and does not always affect the whole species.

> Sometimes, individuals inherit new characteristics that give them a survival and reproductive advantage in their local environments; these characteristics tend to increase in frequency in the population


fastspinecho t1_ivfug13 wrote

My point is that not all evolutionary changes occur throughout a species, so it is wrong to say that evolution "caters to the whole species" with "no regard" for individuals.

In the comments, you can find a discussion of the evolution of the human sickle cell gene. It evolved in a relatively small group of individuals to provide those individuals protection against malaria. Those individuals are not a separate species, and if evolution were actually catering to the species as a whole then the gene would never have evolved.


fastspinecho t1_ivfs9rr wrote

Yes, it is related to speciation. But that does not mean it is acting to change an existing species. It is often acting at a much smaller scale.

In fact the definition you quoted doesn't even use the word species. It refers instead to generations, ie differences compared to one's ancestors.


fastspinecho t1_ivfpz7b wrote

Evolution is much more than just the origin of species. It can be used to describe any individual with different traits than its ancestors, even within the same species.

It's true that an individual cannot evolve over the course of its lifespan. However, evolution fundamentally describes a relationship between multiple individuals (or if you prefer, a "population"), it is not necessarily acting on the entire species.

Elsewhere in the comments you can find a discussion of the sickle cell gene. This is an example of a relatively small population of individuals who evolved resistance to malaria (as well as a deleterious homozygous trait). They most certainly do not constitute a new species.


fastspinecho t1_ivfdg5n wrote

> succesful evolution caters to the whole species, with little regard for the individual

Evolution is a phenomenon that acts on individuals, not species. It is manifested in the differences between an individual and its ancestors. "Species" is an artificial construct to help humans classify and describe individuals.

And evolution simply means "change", it is not "successful" or "unsuccessful" any more than gravity.


fastspinecho t1_iu5aua4 wrote

That doesn't really answer the OP's question.

It's entirely possible that pH is both "stable" (i.e. small standard deviation in normal people) AND significantly different in Alzheimer's.

In fact, the more "stable" it is normal people (i.e. the smaller the standard deviation), the smaller a change needs to be in order to be significantly different in Alzheimer's.

For example, if all healthy people have pH between 7.36 and 7.44, then pH of 7.33 would be evidence of pathology.

That said, I don't believe there is any good evidence that the pH of CSF is significantly in Alzheimer's and controls.


fastspinecho t1_itr3m2f wrote

You can think of primary motor cortex as a "clickable map" of all the muscles in your body. The map can be "clicked" by either side of your brain, causing that muscle to move.

However, half of the map physically resides in one hemisphere, and the other half resides in the other hemisphere. If a hemisphere is lost, then the map is lost and a person will become hemiplegic. This is the same reason why some people are hemiplegic after a stroke. Note that in very young children, the brain can rebuild the map in the remaining hemisphere. But it is very difficult for adults to regain function.

On the other hand, a callosotomy severs some of the structures that the brain uses to reach across and click the map on the opposite hemisphere. It does not sever all of the structures and methods used to transmit information across hemispheres. For example, both hemispheres still have indirect visual and proprioceptive input regarding what is happening on the contralateral side.

So it's hard to predict what will happen, but generally it will be more difficult to coordinate movements.

Here's what happened to one patient:

> We examined bimanual coordination in a patient before and after each stage of callosotomy surgery. We tested how well the patient coordinated movement direction between the hands. The patient drew symmetrical or asymmetrical figures simultaneously with both hands. Before surgery, symmetrical figures were drawn well and asymmetrical figures were drawn poorly. Following anterior callosotomy, the drawings improved slightly. Symmetrical figures were still drawn well, and asymmetrical ones were still drawn poorly. Thus, spatial integration remained intact despite the loss of interhemispheric communication between frontal cortical sites. After posterior callosotomy, spatial coordination deteriorated significantly. Mirror-image drawings became less symmetrical, while asymmetrical drawings improved. These data indicate that the posterior callosum mediates the coordination of direction information between the hands during bimanual movements. Given the topographical organization of the corpus callosum, this integration is likely carried out by parietal cortex.


fastspinecho t1_itqprdh wrote

Your muscles are (mostly) directly controlled by the primary motor cortex on the opposite side of your body. So for example stimulation of the left primary motor cortex might cause your right thumb to twitch.

But that is only the first control layer. There are additional layers that control primary motor cortex, such as premotor cortex and the supplemental motor area. Their job is to help sequence and synchronize the "twitches" produced by primary motor cortex.

And these layers communicate with their counterparts on the other side of the brain. So for example stimulation of your left premotor cortex can produce a complex movement involving multiple muscle groups on both sides of your body.

Secondary motor control centers allow you to not only blink in sync, but also synchronize your leg muscles when jumping, your arms when clapping, etc.