Modeling microalgae cell mass distributions using the Fokker-Planck equation

The modeling of the cell mass distribution for microalgae growth processes is addressed using the Fokker-Planck equation for a stochastic logistic growth model of a single cell. Relations between the proposed model and the classical Droop model used for mass-balance based modeling of the algae growth are established. The proposed model is evaluated using experimentally obtained cell mass distribution data for the microalgae Chlamydomonas reinhardtti showing a good correspondence between measurements and model predictions. The obtained model is considerably simpler in comparison to cell mass population balance models used so far to describe the temporal behavior of the cell mass distribution

Evolutionary temperature compensation of carbon fixation in marine phytoplankton

The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature. Long-term experimental evolution under high temperature reversed the short-term stimulation of metabolic rates, resulting in increased rates of carbon fixation. Our findings suggest that thermal adaptation may therefore have an ameliorating impact on the efficiency of phytoplankton as primary mediators of the biological carbon pump

On the dynamics and robustness of the chemostat with multiplicative noise

The stochastic dynamics of a two-state bioreactor model with random feed flow fluctuations and non-monotonic specific growth rate is analyzed. Using the Fokker-Planck equation approach for describing the probability density function (PDF) evolution the lack of stochastic robustness due to deterministic bifurcation phenomena for the open-loop reactor operating under optimal (maximum production) operation condition is established, and the associated stochastic stabilization problem is addressed. Inherent differences between the presence of multiplicative noise, due to the feed flow fluctuations, and additive background noise are analytically established. Numerical simulation results illustrate these inherent differences, the stochastic fragility of the open-loop operation yielding a stochastic extinction phenomenon, as well as the stochastic PDF stabilization with a proportional feedback control

Transitioning Traditional Aviation Weather Instruction to a Space Launch Weather Support Course: Operational Considerations

Weather support to space launch operations, while similar to that for traditional aviation, presents significant additional challenges. Embry-Riddle Aeronautical University (ERAU) currently offers three courses in traditional aviation meteorology, two needed by aeronautical science students seeking private pilot through airline transport pilot (ATP) FAA certifications, and one to provide meteorology majors with operational experience supporting an actual air race. However, with the advent of a new degree program in Commercial Space Operations (CSO), the need to modify and extend traditional aviation weather instruction to include space launch weather requirements has become increasingly important. While the traditional aviation meteorology coursework is beneficial, it does not cover the full-spectrum of weather impacts on space launch and suborbital space flight operations that both CSO and meteorology students will need. To address this challenge, ERAU (with guidance from the 45th Weather Squadron at Patrick Air Force Base) is working to create a new course focused on weather support to these operations, utilizing the new suborbital space flight simulator and lab housed in the Department of Applied Aviation Sciences. This presentation explores the operational considerations of transitioning traditional terrestrial aviation weather instruction to a suborbital space flight weather support course. These considerations include: more stringent spacecraft and system weather sensitivities, triggered lightning, vertical wind-shear profile analysis, attention to atmospheric conditions above the troposphere, and space weather impacts

Ueber Aminopyrrolidine

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Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom

This is the final version of the article. Available from Springer Nature via the DOI in this recordThe publisher correction to this article is in ORE at: http://hdl.handle.net/10871/34487Diatoms contribute roughly 20% of global primary production, but the factors determining their ability to adapt to global warming are unknown. Here we quantify the capacity for adaptation to warming in the marine diatom Thalassiosira pseudonana. We find that evolutionary rescue under severe (32 °C) warming is slow, but adaptation to more realistic scenarios where temperature increases are moderate (26 °C) or fluctuate between benign and severe conditions is rapid and linked to phenotypic changes in metabolic traits and elemental composition. Whole-genome re-sequencing identifies genetic divergence among populations selected in the different warming regimes and between the evolved and ancestral lineages. Consistent with the phenotypic changes, the most rapidly evolving genes are associated with transcriptional regulation, cellular responses to oxidative stress and redox homeostasis. These results demonstrate that the evolution of thermal tolerance in marine diatoms can be rapid, particularly in fluctuating environments, and is underpinned by major genomic and phenotypic change.This study was funded by a Leverhulme Trust research grant (RPG-2013-335). Whole genome re-sequencing was carried out at Exeter Sequencing Service and Computational core facilities at the University of Exeter, where Dr. Karen Moore, Dr. Audrey Farbos, Paul O’Neill, and Dr. Konrad Paszkiewicz lead the handling of the samples. Exeter Squencing Services are supported by Medical Research Council Clinical Infrastructure award (MR/M008924/1), Wellcome Trust Institutional Strategic Support Fund (WT097835MF), Wellcome Trust Multi User Equipment Award (WT101650MA), and BBSRC LOLA award (BB/K003240/1)

Identification of a cell population model for algae growth processes

The growth process of a Chlamydomonas reinhardtii cell population is modelled with experimental data obtained in a batch reactor. To describe the growth process of this culture, the Droop model, extended by cell population balance model, is considered. On the basis of available measurements and the mathematical model, an optimization problem is defined in order to determine the kinetic parameter values for the growth functions of the Droop model and the cell division parameters of the cell population balance model