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ecology/metabolism.js

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+import {KELVIN_OFFSET, clamp} from './units.js';
+
+const B0 = Object.freeze({ectotherm: 42, endotherm: 310}); // kJ d^-1 at 1 kg, simulator calibration
+const ACTIVATION_EV = 0.65;
+const BOLTZMANN_EV = 8.617333262e-5;
+
+export function ectothermTemperatureMultiplier(temperatureC,referenceC=20){
+  const t=clamp(temperatureC+KELVIN_OFFSET,180,350),ref=referenceC+KELVIN_OFFSET;
+  return Math.exp((-ACTIVATION_EV/BOLTZMANN_EV)*(1/t-1/ref));
+}
+export function basalMetabolismKJPerDay(massKg,temperatureC,physiology='ectotherm'){
+  const mass=Math.max(1e-4,massKg),temp=physiology==='ectotherm'?ectothermTemperatureMultiplier(temperatureC):1;
+  return B0[physiology] * Math.pow(mass,.75) * temp;
+}
+export function starvationHazardPerDay(energyFraction){
+  if(energyFraction>=.18)return 0;
+  return 0.018 + 0.34*Math.pow((.18-Math.max(0,energyFraction))/.18,2);
+}
+export function thermalHazardPerDay(temperatureC,preferredC,toleranceC,physiology='ectotherm'){
+  const excess=Math.max(0,Math.abs(temperatureC-preferredC)-Math.max(1,toleranceC));
+  if(!excess)return 0;
+  return (physiology==='endotherm'?.00025:.0008)*excess*excess;
+}