There are so many variables here. I think most people underestimate the violence involved in a high speed motor vehicle crash. Years ago, I was involved in EMS and responded to a lot of crashes. If we eliminate a) crashes without seatbelts worn (1), and b) crashes without frontal airbags (cars without frontal airbags are relatively uncommon these days, I'd say that most survivable TBIs were caused by either a) side impacts, with the head hitting the window glass, or b) the airbag itself (2). Of those two, the low-to-intermediate-speed side impact is the only one where a helmet would make much difference. Some cars now come with side-curtain airbags, which would help a lot with this.
No doubt, many other crashes result in TBIs, but the forces are so extreme that a small helmet isn't going to help. It's really stunning to see what happens in high-speed impacts.
(1) Without seatbelts, even intermediate-speed impacts result in so much chaotic movement that people tend to fly around inside (or outside) the car and airbags don't help that much. You don't want to be in an ejected-from-vehicle event.
(2) Airbags can definitely cause TBIs by themselves, especially if you're seated very close to them. It's basically a small explosion going off in your face. It's better than hitting the steering wheel or windshield, though.
It seems like diet is a good case of where it might be better to satisfy than optimize: it's clearer that some things are bad than that other things are optimal.
I think that long-term goals should be qualitative and subjective, and supported by short-term goals that are quantitative and objective. I like my short-term goals to be achievable within 12 weeks at the outside, and preferably much less.
One reason for this is that as I learn by pursuing and achieving short-term goals, my outlook on the long term changes. Another reason is that the pursuit of long-term goals is hindered by getting stressed out over specific numbers or metrics, and made easier by pushing the edge of my subjective performance envelope. In other words, if I'm always trying to perform such that I feel mostly positive (which isn't necessarily the same as feeling good!) close to the point where I start to fail, I'm building a long-term positive association with my goal while incrementally improving.
This is easiest for me to illustrate with athletic goals. One of my long-term goals for 2015 is to feel physically light and subjectively strong. One of my short-term goals in support of this is to do 10 reps of the strict overhead press with 95 pounds at a bodyweight of 150 or less. Right now this seems subjectively hard, but I know from experience that I am probably less than 8 weeks from achieving it. When I get there, I'll make another short-term goal based on how I feel subjectively about the long term goal. This is probably too big a short-term bite for an area of practice in which one has little experience; I have many years of physical training experience to go on in making these goals. Some years ago when I had a long-term goal of getting back into coding, my short-term goals were things like "learn how to split a string in Python": something that I should be able to achieve in one sitting.
The shooting sports have a lot of attributes that appeal to different mental aspects of rationality:
Potential drawbacks: associated in the USA with right-wing politics; distrusted by liberals; expensive; requires ownership of dangerous tools.
In the event that exercise becomes a persistent habit, what is optimal changes a lot over time as you age and as you improve.
Speaking from the perspective of having exercised 5-7 days a week for over 20 years now, doing both strength and endurance work, I can say that my interests, capabilities, and my response to exercise has changed in fascinating ways over that time. Most people don't stick with an exercise program long enough to even really understand it, let alone wear it out, but if you do, what you do will probably change a lot.
I realize that's a pretty vague statement, but while I think your advice is pretty good overall, the idea of optimal is not something that stays fixed over long periods of time.
Rebecca Newberger Goldstein writes philosophical fiction. She is my favorite contemporary literary fiction author. Her biographies of Gödel and Spinoza are also brilliant.
In his 1985 paper he seems to be arguing that he uniquely extends the Church-Turing thesis.
Deutsch claims in the article to have proved that any physical process can in principle be emulated at arbitrarily fine detail by a universal quantum Turing machine. Is this proof widely accepted? I tried to read the paper, but the math is beyond me. I've found relatively little discussion of it elsewhere, and most of it critical.
I always recommend that people who are even remotely interested in this kind of stuff take a wilderness medicine course. Wilderness medicine is all about decision making under conditions of limited time and information, so it seems like the kind of thing that would interest LWers.
Well, one answer may simply be that militaries are class-and-tradition-laden bureaucracies that are hostile to change. Certainly this has been the experience of the US when attempting to build a western-style NCO corps into the militaries of allied developing nations.
Another answer might be that it's already possible in principle: somebody has probably already mentioned this, but one can go from a NCO role into an officer role; the traditional term for this is "mustang officer".
Another answer might be division of labor: traditionally, western military officers are required to gain a lot of breadth in their careers, both through academic education and through assignment to different types of field commands, logistical positions, and political positions. This poses a (common) problem for officers who have a personality type that wants depth in one type of military occupation; that role is more traditionally a senior NCO role. It may be, however, that this type of division of labor produces the most effective fighting force; I don't know.