lenticular

That just means that there was an impact at around the same time. There's been numerous impacts like this that have been claimed to be the cause of Younger Dryas in the past. However, just because there was an impact doesn't mean it had anything to do with YD.

The Atlantic meridional overturning current shutdown from a freshwater pulse is much more parsimonious, and is exactly what we would expect from the physics of the Laurentide melt going into the Atlantic.

Impacts still don't explain the multiple advance and retreats during the Laurentide, but it is obvious why that would occur with the AMOC shutdown explanation:

Melting causes the AMOC to shut down, causing nothern hemisphere cooling. The cooling reduces melting, inducing the AMOC to start back up, increasing melting once again.

No, speaking as a former glaciologist, that's not likely to be true. The parent poster is correct. Younger Dryas featured multiple advances and retreats, which is inconsistent with an impact. Multiple impact over many centuries just isn't that statistically likely, and we would see better evidence of it.

Instead, the most probably cause is freshwater pulses coming out of the melting Laurentide ice sheet changing circulation in the Atlantic. This is actually quite well supported.

Younger Dryas was also confined to the parts of the northern hemisphere, mainly in higher latitudes. A large enough impact to significantly alter climate would see the resulting particulates globally mix in the atmosphere, resulting in more uniform cooling.

Instead, the fact that it was confined to parts of the northern hemisphere also supports the freshwater pulse hypothesis, since it is only a change in the transport of heat from the tropics to the pole, not a change in total heat.

The fact that freshwater pulses from the Laurentide ice sheet caused so much cooling is actually a concern with climate change. It's possible that it could happen again with melting of the Greenland Ice Sheet, at least a weakened version of it (the Laurentide Ice Sheet dwarfed the GIS).

Vitamin D deficiency actually really common, especially with dark skinned people living at higher latitudes. Most office people could do with a bit more UV.

> On a side note: Should he have been able to see whose results he was looking at? It's surely unethical in my book.

They were specifically ones from his own family, so I imagine he had consent.

Whoops, brain fart.

Sequential access is O(1) just like mutable arrays. These structures really are fast and practical. The benefits of immutability are enormous. That's why they are so popular.

Edit: That's true about log32 and log2 become close in the limit, but that's irrelevant for practical data sizes. For example,

log2(10^6) ~ 20,

log32(10^6) ~ 4

That's a 5x difference.

Modern persistent tree-based data structures are usually O(log32n) random access, which is essentially O(1) for all practical purposes. With a mutable array of references, random access follows one pointer, while these structures follow usually less than 5. Sequential access is usually O(1).

These kind of persistent data structures are already the standard data structures in Scala and Clojure, and they are fast enough for the vast majority of non-numerical purposes. In typical access patterns, they are faster than mutable arrays.

These persistent structures use what's called structural sharing. The simplest persistent structure is just a regular linked list. While random access is O(n), inserting, deleting, or concating is O(1). Since the list is not mutated, we can insert an element to the head of the list just by taking the new element and making a pointer between it and the original list. The original list is not modified, nor is it copied.

More sophisticated persistent structures like Funkia List have O(log32n) access, which is basically constant time. This makes them better general-purpose data structures than mutable arrays.

It's subjective, but I've really got to disagree with you that vests look good. They're pretty hard to pull off, IMO.

I probably wouldn't worry about it unless you have really large arrays. It's still probably pretty insignificant compared to the time spent updating the DOM.

We used to say that in Seattle.

Residents don't sleep much, so this doesn't surprise me at all.

Related, the residency process needs to be massively reformed. The flimsy justification for making people responsible for human lives work 80 hours a week is usually that the long hours help them learn faster. But that's really BS. The brain has an incredibly hard time forming new memories when sleep deprived.

I know a couple of nurses who often talk about how spaced-out residents are at night. They'll page them to consult on something, usually waking them up. The residents will usually just blearily agree with whatever the nurse was planning on doing, so they aren't getting in meaningful physician supervision.

Yeah, Neanderthal is great (I'm a Clojure a user). It's got support for structured sparse matrices (like Toeplitz) the last I checked, but not general CSC/CSR matrices.