Tuesday, March 02, 2021

Another Wave?

      Successful prediction is often a downer.  TV news this morning is reporting that the CDC is concerned we may be in for another wave.   The decline in new infections in the U. S. had slowed, stalled -- and is starting to climb.

      Tam can tell you that I was thinking we'd see another peak; I told her a couple a weeks ago that there was a race on between vaccination (and overall immunity), the new and more communicable strains of the virus, and springtime impatience.

      Even in a year not haunted by a pandemic, many people greet the end of winter with renewed activity -- and after a stunted holiday season, with plummeting infection rates and mass vaccination underway, what normal person wouldn't be optimistic?  When we extrapolate from past events-- you, me or popular media pundits -- we do so linearly: "if this keeps on--"  And the graph looked good.

      It didn't keep on.  It's a lagging indicator in an under-damped feedback loop.*  When the winter storm stalled vaccine deliveries, when approval of Johnson & Johnson one-shot vaccine kept on being "right around the corner" for weeks, we fell behind in the race against mutations.†

      So I'm betting on another peak.  How tall, for how long -- I've no idea.  By now, most people have seen this thing wax and wane; many people have lost friends and family, or friends of friends, and are less inclined to shrug it off.  Others are frustrated.  A growing proportion of us are immune (how immune and for how long, we don't know).  How will it play out? 

      I don't know.  Here's hoping for the best.  The fourth wave of the 1917 - 20 influenza epidemic had significantly lower infection and mortality rates than the second and third.  We adapt.  We learn.
* Most complex systems with behavior controlled in part by past output act like a phase-locked loop.  Your home thermostat and furnace is a simple PLL.  They "hunt" to stability; the temperature in your house varies up and down a few degrees during heating or cooling season, with the thermostat turning the heating or cooling on and off.  A good system has only a little variation; it is "critically damped."  The furnace has to be well-sized for the load: too small a furnace, and it runs all the time and falls behind ("overdamped") -- too powerful, and you alternately sweat and shiver as it clicks on, dumps in too much heat too quickly, and switches off, over and over.  The latter case is "underdamped."  And our species-wide response to many kinds of threats is underdamped -- en masse, we keep dancing right up to the edge and a little too far, then back way off. Rinse, lather, repeat.  With a week or two between exposure and full-on illness and a death rate lagging a week or two behind that, this virus inherently creates an underdamped response: by the time we have a good, clear sign of trouble, we're already behind the curve.
† What self-respecting SF writer can type that phrase in earnest and not blink?


Carteach said...

Being a relatively non-social person, I feel like I've trained my whole life for these circumstances.

Your example of a feedback loop and home heating brought on some thoughts. The answer to the over/under damping issue would be a variable output heating device. Most units have two speeds... on or off. The electric element is either on, or off. The furnace gun is either spraying fuel oil, or not.

Well, that need not be. In electric heating situations, we could move to Pulse Width Modulation as a control method. This would conceivably reach zero-cycle.
In fuel oil (or gas) furnaces, we could use multiple injectors or variable pressure injection with air pressure vaporization at the nozzle. Same results.

Roberta X said...

Some air-conditioning systems do incorporate varying degrees of "modulation," often in the form of variable-frequency drive to motors in fans and compressors. Overall system sizing remains an important consideration, but it does help. At this point, there are significant cost trade-offs. That will almost certainly improve.

But when it comes to people, well, we're pretty much as we have always been. That's not likely to change.

fillyjonk said...

I am fearful that we as a nation are about to snatch defeat from the jaws of victory by re-opening fully too soon. At least wait a few more ding-dang months before you go to 100% occupancy everywhere, let more people get vaccinated!

I mean, I am lonely and bored and tired of making lists for my once-every-10-day trip to the grocery that rival D-Day plans, I want to get back to being able to go "hmmm I feel like cooking chicken tonight" and stop off at the grocery on the way home, but I don't feel like it's quite time for that yet.

(honestly for me the worst thing have been the alterations to how I have to teach, all the added duties of Online Availability and being part of the frontline for track and trace if a student gets infected. Too fast of a reopening is only going to mean I have to deal with that LONGER - we are already talking about a fall term like this, and maybe even spring term 2022. And I want to quit, I am so tired of this and burnt out and my job is no longer rewarding)