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Joined 2 years ago
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Cake day: June 29th, 2023

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  • I’m not sure I’d call US sunscreens way worse (they are still very effective at blocking UVB, just not UVA as effectively), but there are definitely better options abroad. There definitely aren’t many options; that’s part of why Hawaii banning two common sunscreen ingredients for marine toxicity reasons was such a big deal.



  • I got one because I was intrigued by its lead rotation, but I found that it really didn’t rotate the lead enough while I wrote. I kept having to rotate the barrel manually to keep a thin line like I do for every other mechanical pencil, and then would get annoyed every time the clip came around to brush my hand. I’ve been wondering if I’m doing something wrong, or if Japanese just uses more shorter strokes. Do you also like it when writing English?



  • So I found this website that lists specific heat capacities for various foods, and while it doesn’t list “snacks”, dry foods values seem to range from 0.3 to 1 cal•g-1•K-1 = 0.0003 to 0.001 Cal•g-1•K-1. Assuming no phase change (i.e., melting) and otherwise temperature-invariant heat capacity, the energy required for heating a 100 g snack from freezer temps (-18 °C) to body temp (37 °C) is 1.65 to 5.5 Cal. More realistically, we can compare to eating an ambient-temp (20 °C) snack; that difference is only 1.1 to 3.8 Cal… in either case, the difference is negligible, generally < 1% of the calorie count of the snack itself.


  • I think the biggest difficulty when starting out is that you don’t know common endings and syllable structure, and so it can be hard to parse where the morphological boundaries lie. It’s much easier once you understand those, though you will still find instances where two components are combined in an unintuitive (for the learner) way, particularly if the translation maps to a (apparently) indivisible root in the learner’s language.



  • Löschen can also mean to offload cargo from a ship…

    I did not know this one either, and it seems even more different from delete/erase/extinguish. I had to look this up; wiktionary says that the unloading sense is actually from a different root (MND lössen, cognate with “los”), which may have changed due to association with the “erasure” sense, particularly in the context of erasure from ship inventories and logbooks.

    Also, thank you for the context. This kind of detail tends to be extremely difficult to search for.




  • In fluent speech, the conjunction (the first “that”) is unstressed, and as a result some speakers reduce the vowel a bit toward schwa. However, if you told those speakers to carefully pronounce each word, I bet they would pronounce the conjunction and the pronoun the exact same same. A more common example of this kind of reduction is the word “to”, which is almost always reduced to /tə/ ([tə] ~ [tʊ] ~ [ɾə] depending on dialect and surrounding words) in everyday speech when unstressed.

    Fun fact, you can reduce just about every unstressed vowel in English to schwa (if it’s not already a schwa) and still be largely understood.



  • In grocery stores in many parts of the US at least, it is extremely hard not to find bread in plastic bags. Even the one of 3 near me that has its own bakery puts the bread in a plastic bag, and then in another bag that is paper with a plastic “window”, and the paper part has a PE wax lining for god knows what reason.






  • Man I just built a new rig last November and went with nvidia specifically to run some niche scientific computing software that only targets CUDA. It took a bit of effort to get it to play nice, but it at least runs pretty well. Unfortunately, now I’m trying to update to KDE6 and play games and boy howdy are there graphics glitches. I really wish HPC academics would ditch CUDA for GPU acceleration, and maybe ifort + mkl while they’re at it.


  • So many solver solutions that day, either Z3 or Gauss-Jordan lol. I got a little obsessed about doing it without solvers or (god forbid) manually solving the system and eventually found a relatively simple way to find the intersection with just lines and planes:

    1. Translate all hailstones and their velocities to a reference frame in which one stone is stationary at 0,0,0 (origin).
    2. Take another arbitrary hailstone (A) and cross its (rereferenced) velocity and position vectors. This gives the normal vector of a plane containing the origin and the trajectory of A, both of which the thrown stone must intersect. So, the trajectory of the thrown stone lies in that plane somewhere.
    3. Take two more arbitrary hailstones B and C and find the points and times that they intersect the plane. The thrown stone must strike B and C at those points, so those points are coordinates on the line representing the thrown stone. The velocity of the thrown stone is calculated by dividing the displacement between the two points by the difference of the time points of the intersections.
    4. Use the velocity of the thrown stone and the time and position info the intersection of B or C to determine the position of the thrown stone at t = 0
    5. Translate that position and velocity back to the original reference frame.

    It’s a suboptimal solution in that it uses 4 hailstones instead of the theoretical minimum of 3, but was a lot easier to wrap my head around. Incidentally, it is not too hard to adapt the above algorithm to not need C (i.e., to use only 3 hailstones) by using line intersections. Such a solution is not much more complicated than what I gave and still has a simple geometric interpretation, but I’ll leave that as an exercise for the reader :)