Ph.D. Remote sensing, Physics of Remote Sensing, University of Sherbrooke, Qc, Canada (2013-2018)
M.Env. Research, University of Sherbrooke, Qc, Canada (2009-2012)
B.Sc. Ecology, Co-op, University of Sherbrooke, Qc, Canada (2004-2007)
Carina Poulin
(Scientific Designer)
| Email: | carina.poulin@nasa.gov |
| Phone: | 000.000.0000 |
| Org Code: | 616 |
| Address: |
NASA/GSFC Mail Code 616 Greenbelt, MD 20771 |
| Employer: | SCIENCE SYSTEMS AND APPLICATIONS INC |
Education
Selected Publications
Refereed
2018. "Diel variations of the attenuation, backscattering and absorption coefficients of four phytoplankton species and comparison with spherical, coated spherical and hexahedral particle optical models." Journal of Quantitative Spectroscopy and Radiative Transfer 217 288-304 [10.1016/j.jqsrt.2018.05.035] [Journal Article/Letter]
2018. "Diurnal variations of the optical properties of phytoplankton in a laboratory experiment and their implication for using inherent optical properties to measure biomass." Optics Express 26 (2): 711 [10.1364/oe.26.000711] [Journal Article/Letter]
2013. "The impact of light pollution on diel changes in the photophysiology of Microcystis aeruginosa." Journal of Plankton Research 36 (1): 286-291 [10.1093/plankt/fbt088] [Journal Article/Letter]
Non-Refereed
2024. "Life after launch: a snapshot of the first six months of NASA’s plankton, aerosol, cloud, ocean ecosystem (PACE) mission." Sensors, Systems, and Next-Generation Satellites XXVIII 14 [10.1117/12.3033830] [Proceedings]
Talks, Presentations and Posters
Other
Observing bioluminescence first flash kinetics of dinoflagellate individual cells using a low-shear stress millifluidics approach
2022
Bioluminescent dinoflagellates emit light when exposed to shear stresses above a certain threshold. Studying how flow can trigger individual cell flashes and observing their kinetics can help us understand how bioluminescent flashes occur in nature. We devised a unique millifluidics apparatus essentially composed of a syringe pump and a glass capillary where dinoflagellate cells are injected. The first bioluminescent flash of cells was captured using a camera. Flashes were tracked from the onset of the first visible emission of light to the last, and integrated densities of flashes were obtained for every frame of the video. Living cells were counted downstream in a second glass capillary using a 405 nm laser and a camera capturing red fluorescent flashes from chlorophyll, and counter-verified by microscope counts. We modeled the velocity and shear stress cells experienced in the system from the dimensions and measured flow rates using ANSYS Fluent. The cells reached a maximum average shear stress of 0.5 N/m2, five times the reported shear threshold for Pyrocystis fusiformis. We observed the typical “first flash” waveform, consistent with what had been measured with other methods, and roughly ten times more intense than the following flashes for P. fusiformis. Our results indicate that a higher level of shear stress could produce a higher flash intensity. The proportion of cells flashing increased with higher shear stress within the studied range. Our method also allowed us to observe the flow-stimulated kinetics of the first flash to study the photoinhibition of bioluminescence in Pyrocystis fusiformis.
Evaluating holotomography as a new way to measure the refractive index of phytoplankton
2020
The refractive index of phytoplankton directly affects their optical properties, particularly backscattering, and by extension, their observation by remote sensing. It has notably been linked to intracellular carbon concentration, making it an important factor for ocean carbon cycling monitoring. Measuring refractive indices of inhomogeneous particles has historically been challenging, with the most common approach being the immersion of particles in liquids of different known refractive indices until they become difficult to discern under a microscope or until the turbidity attains a minimum. Other ways include inversion of scattering from a flow cytometer using the Lorentz-Mie theory. However, these methods do not allow the observation of sub-cellular refractive index structures, which are believed, from modelling studies, to strongly influence backscattering. A new technology, holotomography, consisting of a 3-dimensional microscope measuring the scattering of a 520 nm laser beam at 45° to calculate refractive indices at a resolution of 200 nm, allows measuring the refractive index of particles in more details than it was ever possible before. We share our observations of phytoplankton with holotomography to evaluate the limits and possibilities of the new technology. We found that holotomography allows detailed measurements of phytoplankton cellular structure and of the repartition of the refractive indexes within cells and also cell assemblages. Limits of the technique include spatial resolution and optimization is necessary to observe thin outer cellular structures. Furthermore, the method allows the measurement of the volumes of intracellular structures as well as the observation of the three-dimensional shapes of the cells and of their internal structures. These parameters, obtained with holotomography, will be included in optical models to evaluate their impact on model closure.