I'm not convinced that it's not possible to design a program of drills that teach a useful response to the every-6000-year problem of "your school is under attack", without injuring the mental health of the students to the point where it isn't worth doing. (Whether it's then worth the time from the school day is another question, which depends on how or whether you value that time to begin with.)

Is there a similar problem with the mental health costs of fire, tornado, and earthquake drills being remarkably high? Having experienced those drills, and seeing the complaints about active shooter drills inflicting trauma, I'm left concluding that the active shooter drills are a fundamentally different kind of practice than other emergency drills. We could abolish them and book a net win, but maybe we could also make them like the other drills instead, and thus make them cost-effective to do, for an even greater benefit.

It could be the case that the other drills are similarly dangerous to mental health, but they have benefits that justify their costs, due to the other kinds of emergencies being more common. Or, it could be that none of the emergencies are worth the mental health costs of drilling for, but we just happen to be examining this one right now. Or, it could be that broadly comparable physical drill activities are much more damaging to one's mental health when one is told one is practicing for being attacked by a human, rather than a tornado, and the kids will figure it out no matter what kind of drill you claim it is, and there's no way to make an active shooter drill safe enough to do. Or it could be the case that nothing you could teach in a reasonably safe drill is going to be particularly effective in an actual attack.

But I don't buy Zvi's equivalence between anything one could describe as an "active shooter drill" and damaging children's mental health. All we know is that current practice appears to be damaging children's mental health.

I bought a single-hose AC unit. I knew two-hose units existed, and that a two-hose design intuitively seems to be the way to go for good thermodynamic reasons, but I did it anyway. This was mostly, as I remember, for four reasons:

1. Apparent air-conditioner experts seemed to think the one-hose models worked OK and that hot air infiltration was a manageable problem. Especially for the cool-a-single-inhabited-room application.
2. The one-hose models were significantly cheaper. This in turn translated to solving my problem significantly sooner, because I did not need to save for longer to afford it.
3. I was already going with a portable unit rather than a window unit, because I anticipated needing to move it every day, and the one hose model had... one hose to hook up and unhook every time.
4. I only recognized the need to buy an air-conditioner on hot days. On cool days, I did not feel like spending the money. So when I actually made my purchasing decision, I bought a plausible and available unit over the optimal unit, to ensure that a unit was bought.

On the design side, while clearly it would be better not to suck warm air into the room if you don't have to, the engineers are up against competing problems:

1. You are working with a much smaller intake. Compare the intake on the back of your unit to the area of the output hose. Even your makeshift intake duct has a much higher area than the normal hoses. When the intake is smaller, you need faster flow, and more fan to make that happen.
2. You need more internal ducting inside the unit. You can't just draw room air more or less straight over the heat exchanger like in a refrigerator, and then blow it out; you need to internally go from a small intake hose to a big heat exchanger to a small output hose, all without mixing with the room air, and you need another completely separate pathway for the room air.
3. You still need a room air intake.
4. You need an additional fan. The room air and the outdoor air can't be pushed by the same fan if they are isolated loops. The additional fan makes additional noise. A single-hose system can use one fan and divide the air for the two paths.
5. You have to fit the intake into the window opening in addition to the exhaust. You can't usually use as much window as you are covering in your experimental setup, it has to fit in a much smaller area or people will reject the solution. My unit had two plastic pieces that nest and slide over each other to adapt to the width of your window, with an opening for the exhaust to snap into. If you tried to add another opening to that design, it would be obstructed at small window sizes, so you would either need to accept only fitting large windows, find some other way to adapt to widows of varying width, or make the hoses even narrower and the flow even faster.
6. You are dumping the heat into warmer air. This is harder to do than dumping heat into cooler air. You might need a better heat exchanger.

As it was, my single-hose unit was bumping up against size, weight, cost, and noise limits. While it might be able to do more cooling per watt if given another hose, it might also then not meet other design constraints, and thus not actually solve my problem.

If we are facing a truly bad new variant, a vaccine update will not save us, because our Public Health Authorities have zero interest in finding a way to make the timeline work.

I'm, personally, quite interested in finding a way to make the timeline work. I'm also quite interested in making the timeline work for preventing infection with the current circulating variants. Then we can start on the common cold.

Is the plan around here to actually listen to the public health authorities on this? Or is something being organized to route around these sorts of regulatory failures? (For example, by manufacturing and distributing up-to-date vaccines within a state only, to keep them out of interstate commerce.) Nobody working on RaDVaC seems to have yet been arrested; maybe doing more of that and trying to make it more accessible to non-microbiologists would be more better?

Or is the potential gain in terms of coronavirus cases and deaths prevented by faster action not going to be worth the cost of annoying the relevant authorities, plus the cost of doing the actual work, plus the risk of doing it wrong?