@spmanipulator @andjrison @GidMK Colour vision is weird, and a lot more complicated than one might at first think.

For a greenhouse project, we had the idea of using red-blue grow LEDs (mostly red, since it's super-efficient) for primary grow lighting but mixing in various small amounts of (inefficient...
@spmanipulator @andjrison @GidMK yellow) HPS with the idea of shifting the appearance of the light over the course of the day for our guests, from reddish sunrises to yellow dawn to white daylight. You know, we'd have red, yellow, and blue, and just blend through them in the right ratios - easy, right? Except...
@spmanipulator @andjrison @GidMK it totally didn't work in testing. If there was almost any blue at all (we couldn't fully shut off the channel), it looked purple/pink, unless the (inefficient yellow) HPS was cranked *way* up, wherein you'd get yellow light. And only with *tons* of blue and little of the...
@spmanipulator @andjrison @GidMK efficient red, you'd get white.

What's going is that we have different "axes". So-called "red" and "green" are actually heavily overlapped and are antagonistic; they both activate from the same light, but if one activates more than the other, then that indicates whether you're.. Image
@spmanipulator @andjrison @GidMK more to the greener end or the redder end of the spectrum. You also have a "red+green" intensity value, the combined activation of these cones. On the other hand you have blue off doing its own thing, giving an intensity value. So your brain works a red-green ratio; a... Image
@spmanipulator @andjrison @GidMK red+green intensity; a blue intensity; and a blue vs. red+green intensity.

In a normal blackbody spectrum (like the sun or any hot glowing object), there's very little blue at all in your "warm light" spectrums, like sunsets, fire, etc. But in your "cool white / daylight"... Image
@spmanipulator @andjrison @GidMK light, there's tons of it. So the ratio between the blue components and the red+green components determines how warm or cool the light looks.

In a blackbody spectrum, when you do have blue present, longer wavelengths are much more shifted to green than red. So it's natural to.. Image
@spmanipulator @andjrison @GidMK have blue when you have a red-green ratio on the green end. But when it's on the red end, that's an "unnatural" situation, often the result of pigments or other phenomena, and we perceive that as purple/pink.

So in short, if we wanted to use HPS to make a natural white light,.. Image
@spmanipulator @andjrison @GidMK we had to really over dominate the red from LEDs, and really heavily pump up the blue, because that's what's needed to get more blue activation than red+green while having the red-green ratio be green-shifted. And while trying to achieve sunrise colours, we could hardly have ... Image
@spmanipulator @andjrison @GidMK any blue whatsoever, because again blue is hardly found in reddish blackbodies, so it gives you an unnatural purple look, even in small amounts.

(The real answer to doing what we wanted to do: red plus tunable-white LEDs. Tunable whites can shift from a warm light to a... Image
@spmanipulator @andjrison @GidMK daylight on their own, and so add in efficient deep red for sunrise / sunset - the longer the wavelength in the PAR range, the better, because you can deliver more moles of PAR relative to how bright it seems)

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More from @enn_nafnlaus

1 Dec
More detail on the preliminary Omicron data reported by Israel the other day:

jpost.com/health-and-wel…

Beyond the mentioned:
* +30% transmission
* boosted=90% protection v. infection (was 95%)

It's:
* boosted=93% protection vs. severe (same)
* 2,4x more severe strain than Delta
The 2,4x more severe ("those not inoculated have a 2.4 times greater chance of developing serious symptoms") runs contrary to the narrative being spun in some African nations that it's a "mild strain" - statements often made right before insisting on lifting the travel bans.
Statements that - I should add - were just repeated by an anonymous WHO official, along with claims that vaccine efficacy isn't reduced, and also demanding the lifting of travel bans:

news.sky.com/story/covid-19…

This is all so preliminary, though, so again, massive grain of salt.
Read 6 tweets
30 Nov
A reminder when viewing exponential growth charts: a wave with faster case growth, plotted against waves with slower growth, will *inherently* seem to take longer for hospitalizations, ICU admissions and deaths to "catch up". Simulated scenario with varying doubling times below. Image
In the above graphs, the slower waves were seeded with more initial cases, so that the faster growing waves past the slower ones on day 27. But hospitalizations don't pass until day 34, ICU admissions until day 38, and deaths on Day 41.
This is an inherent result in the delay between cases and more severe outcomes. If case growth reaches a given height corresponding to an earlier wave, but at a faster growth rate, it hasn't had as much time for cases to become more severe - thus they plot lower vs. cases.
Read 5 tweets
28 Nov
Since comments were shut down on this thread... a reply thread.

1) The existence of a finite number of things that professionals have been wrong about in their field does not in any way imply the likelihood that a random person is likely to be more correct than professionals.
E.g., if climatologists get some specific detail of climatology wrong in regards to *rapidly evolving news*, that doesn't mean that one should listen to John Doe over the IPCC.

2) When one posits "theoretical harms" of COVID restrictions up against the actual measured harms...
.... the real, demonstrable harms win. I used excess death figures to avoid the "died with COVID vs. died of COVID" red herring. And to be clear: yes, these excess deaths are mainly due to respiratory disease, & to a lesser extent cardiac - the way COVID kills people.
Read 18 tweets
26 Nov
To anyone repeating the "B.1.1.529 is due to a lack of vaccine sharing" line: South Africa is not vaccine limited, and hasn't been for months. They've been vaccinating children 12+ for a month. Anyone there can get vaccinated just by showing up. The problem is hesitancy.
A friend of mine from SA messaged me the other night as I was going to sleep, to complain about the mess over there. He has multiple comorbidities, but almost nobody around him is vaccinated. Lots of cases of companies even banning vaccinated people because of "spike shedding".
His company is making everyone (incl. software developers) work at the office. Not for work-related reasons - so they can do extracurricular "bonding activities". A coworker has an adopted child with HIV (immunocompromised & vulnerable) who sought an exemption. Exemption denied.
Read 6 tweets
14 Nov
I was today years old when I learned that all six of the programmers behind ENIAC, the first digital computer, were women (whose work went almost entirely unrecognized until the 1980s).

en.wikipedia.org/wiki/ENIAC

Their first program was nuclear simulations for a hydrogen bomb.
The six - Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty - were "human computers" who got their positions due to wartime labour shortages. They kept their jobs after the war because their experience was too difficult to replace.
As generative programming languages did not yet exist, "programming" ENIAC meant switches and rewiring cables, which required a full understanding of its blueprints. Photos of them next to ENIAC referred to them as "refrigerator ladies" & they had to serve as hostesses for guests
Read 14 tweets
1 Nov
@elonmusk @MartinKulldorff @joerogan @DrJBhattacharya Sorry, Elon, but this article is fringe.

1 . "Mounting evidence indicates that natural immunity is stronger and longer lasting than vaccine-induced immunity." - Here's a meta-review of the entire corpus. No, it is not.

cdc.gov/coronavirus/20…
@elonmusk @MartinKulldorff @joerogan @DrJBhattacharya 2. "In a study from Israel..."

Hmm, what does the text say at the top of that "Study from Israel", I wonder?
@elonmusk @MartinKulldorff @joerogan @DrJBhattacharya The "study from Israel" is a non-peer-reviewed preprint that not only contradicts the rest of the corpus, but does so by *over an order of magnitude*. Giant flashing red lights with loud sirens should be going off in your head by now.
Read 29 tweets

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