caper

> Your file system is now a random collection of little special permissions that you can neither view nor remove. Welcome to the future of macOS security.

I would be curious if anyone has any clever ideas of how to mitigate.

There is slight possibility I'm interpreting like I'm 5, so don't take this as gospel and please anyone else issue corrections, also it's a gross oversimplification but here goes:

First a brief outline of the actual experiment. Rather than directly measure all of the processes that occur within a plant to effect photosynthesis (from photons hitting a leaf and water being drawn from the ground to the creation of some sort of molecule used for transporting energy in plant cells e.g. ATP) the researchers cited in the article created a mathematical model of part of the process that directly concerns chlorophyll: absorbing photons and transferring the energy to the next stage. They don't specify what the next stage would be, they simply modelled a network of nodes from input (representing the initial photon hitting), via nodes representing different stages of chlorophyll, to a generic output.

The models assumed two things indicated by prior research: 1) there is an upper threshold of energy production beyond which deleterious back reactions occur i.e. chlorophyll make too much power do nasty thing to plant 2) there is a lower threshold of energy production beyond which eventual power output is inefficient (nonlinear decrease in output) because the rate of energy transfer out of the network [from the chlorophyll stages to the next part of photosynthesis] is fixed by electrochemical processes i.e. chlorophyll make too little power makes actual photosynthesis even worse

Given those assumptions an ideal chlorophyll stage would operate between the thresholds. In a static environment, that is one in which the rate and state of photons entering remains constant, this could be easily achieved. In a noisy environment, when the light source fluctuates as a result of shadows etc., then a system that relies on one absorption rate will see a direct corresponding fluctuation in power output - fewer/more photons in means less/more energy out and importantly the rates of power in to power out would be directly linked. This noisy environment could cause a drop below / rise above the 2 thresholds above and therefore bad/inefficient operation. Given this noisy environment is inevitable an ideal chlorophyll stage would smooth out the fluctuations in input energy so the output doesn't spike in direct relation to input spikes. Think here of adding capacitors to smooth current fluctuations. This smoothing can be achieved by having two (or more - this is limited by biological/chemical realities here) different concurrent input sources that flow energy through the system at different rates given they both produce the same output. Krackers has more clearly explained this bit than I did initially - although I must add the differing energy production rates is my interpretation of what's implied by the authors because they don't explicitly explain.

I have ignored here the internal noise of the system which the paper attributes to protein dynamics driving fluctuations of intermediate excitation energy transfer events for simplification and because it doesn't effect the main thrust.

Interesting - why would fluctuation of the energy flow into the biochemical cascade cause an increase in free radical production?

If this is the case then seems a lot more likely and evolutionarily sound than the efficiency interpretation; unless there is some second order effect of the rate of photosynthesis on its efficiency/completion that couple with some sort of initial energy barrier I struggle to see how smoothing fluctuations by using non-proximal wavelenghts would be more efficient than allowing fluctuations with greater absorption across the spectrum (and so greater net energy absorption). Some more basic survival mechanism like the free radical one you propose just seems to be more intuitive. With green colouration a circumstantial bedfellow of the other chemical properties rather than the master. Still speculative of course.

Keen to hear your thoughts.

Blue and red are the maxima but chloropyll does absorb green light too - just less of it (and possibly less efficiently). The article claims "[plants] absorb only about 90% of the green photons." which seems to be a typo and should be absorb 10% or reflect 90%. I'm having great difficulty obtaining complete absorption spectra from the literature - nobody seems to have bothered investigating since the 1950s (https://sci-hub.se/https://pubs.acs.org/doi/10.1021/cr60147a...) with most modern papers seemingly content with declaring the red/blue maxima and not giving the full range.

The paper I linked shows nonzero absorption for greenish wavelengths approaching 10% towards yellow - which would marry with my interpretation of the article's typo.

I think it has actually more to do with "But they also needed to absorb light at different rates to buffer against the external noise caused by swings in light intensity." To create this buffering one would ideally have the the least proximal wavelengths, which will presumably be least similar in downstream rate of conversion/transportation and therefore smooth energy flow from the flickering, but which are still at near peak intensity. In this case that's blue and red visible light. The article notes they are at the steepest part of the intensity curve which is just a proxy definition for the above criteria.

This of course still assumes that their model of generalised networks is analogous to the real biological cascades - otherwise could just be another coinciding superficiality rather than evolutionary reality (https://news.ycombinator.com/item?id=33050912). Quick skim through the source paper on SciHub leaves me sceptical.