Territorial Differential Meta-Evolution (TDME) is an efficient, versatile, and reliable algorithm for seeking all the global or desirable local optima of a multivariable function. It employs a progressive niching mechanism to optimize even challenging, high-dimensional functions with multiple global optima and misleading local optima. This paper introduces TDME and uses standard and novel benchmark problems to quantify its advantages over HillVallEA, which is the best-performing algorithm on the standard benchmark suite that has been used by all major multimodal optimization competitions since 2013.
View Article and Find Full Text PDFDroughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more.
View Article and Find Full Text PDFGross ecosystem productivity (GEP) in tropical forests varies both with the environment and with biotic changes in photosynthetic infrastructure, but our understanding of the relative effects of these factors across timescales is limited. Here, we used a statistical model to partition the variability of seven years of eddy covariance-derived GEP in a central Amazon evergreen forest into two main causes: variation in environmental drivers (solar radiation, diffuse light fraction, and vapor pressure deficit) that interact with model parameters that govern photosynthesis and biotic variation in canopy photosynthetic light-use efficiency associated with changes in the parameters themselves. Our fitted model was able to explain most of the variability in GEP at hourly (R = 0.
View Article and Find Full Text PDFPermafrost contains about 50% of the global soil carbon. It is thought that the thawing of permafrost can lead to a loss of soil carbon in the form of methane and carbon dioxide emissions. The magnitude of the resulting positive climate feedback of such greenhouse gas emissions is still unknown and may to a large extent depend on the poorly understood role of microbial community composition in regulating the metabolic processes that drive such ecosystem-scale greenhouse gas fluxes.
View Article and Find Full Text PDFAn intensity-stabilized diode laser absorption spectrometer was developed and used to perform a highly accurate study of the line shape of CO(2) absorption lines, in the spectral region around 5000 cm(-1), belonging to the nu(1) + 2nu(2)(0) + nu(3) combination band, at a temperature of 296.00 K. Standard and complex semiclassical models, including Dicke narrowing and speed-dependent broadening effects, were applied, tested, and compared in the pressure range between 0.
View Article and Find Full Text PDFAn intensity-stabilized laser absorption spectrometer, which incorporates a mirror-extended cavity diode laser, a temperature-stabilized gas cell, and a Michelson interferometer, was developed and applied to a highly accurate investigation of line intensity factors within the nu(1)+2nu(2) (0)+nu(3) combination band of carbon dioxide, around 2 microm wavelength, at a temperature of 296.0 K. This relatively complex apparatus enables one to observe the absorption line shape with high precision and accuracy in such a way that it is possible to retrieve the integrated absorbance with a relative uncertainty better than 0.
View Article and Find Full Text PDFThe temperature and pressure cycles inside a pressure modulator cell (PMC) of the type used for gas-correlation radiometry aboard the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument have been determined from dynamic measurements of the spectral line shapes of the R(0) and R(18) transitions in the fundamental vibrational-rotational band of carbon monoxide. The line strengths and linewidths were used to calculate the temperature and pressure, respectively, with a temporal resolution of approximately 200 micros, or 1/100 of a PMC cycle. The results are compared with a thermodynamic box model.
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