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  • Massachusetts Institute of Technology and Woods Hole Oceanographic Institution  (60)
  • Cell Press
  • Springer Science + Business Media
  • 2020-2023  (67)
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  • 1
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Master of Science in Aeronautics and Astronautics at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2020.
    Description: Contemporary scientific exploration most often takes place in highly remote and dangerous environments, such as in the deep sea and on other planets. These environments are very hostile to humans, which makes robotic exploration the first and often the only option. However, they also impose restrictive limits on how much communication is possible, creating challenges in implementing remote command and control. We propose an approach to enable more efficient autonomous robot-based scientific exploration of remote environments despite these limits on human-robot communication. We find this requires the robot to have a spatial observation model that can predict where to find various phenomena, a reward model which can measure how relevant these phenomena are to the scientific mission objectives, and an adaptive path planner which can use this information to plan high scientific value paths. We identified and addressed two main gaps: the lack of a general-purpose means for spatial observation modelling, and the challenge in learning a reward model based on images online given the limited bandwidth constraints. Our first key contribution is enabling general-purpose spatial observation modelling through spatio-temporal topic models, which are well suited for unsupervised scientific exploration of novel environments. Our next key contribution is an active learning criterion which enables learning an image-based reward model during an exploration mission by communicating with the science team efficiently. We show that using these together can result in a robotic explorer collecting up to 230% more scientifically relevant observations in a single mission than when using lawnmower trajectories.
    Description: This work was partially supported by the National Science Foundation (NSF) Award #1734400, as well as by the Woods Hole Oceanographic Institution (WHOI). The author would like to thank both organizations for their support.
    Keywords: Robotics ; Autonomous ; Exploration
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 2
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physical Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2020.
    Description: A detailed understanding of the intensity and three-dimensional spatial distribution of diabatic abyssal turbulence is germane to understanding the abyssal branch of the global overturning circulation. This thesis addresses the issue through 1) an investigation of the dynamics of an abyssal boundary layer and through 2) the construction of a probabilistic finescale parameterization using mixture density networks (MDNs). A boundary layer, formed by the interaction of heaving isopycnals by the tide and viscous/adiabatic boundary conditions, is investigated through direct numerical simulations (DNS) and Floquet analysis. Turbulence is sustained throughout the tidal period in the DNS on extra-critical slopes characterized by small slope Burger numbers, leading to the formation of turbulent stratified Stokes-Ekman layers. Floquet analysis suggests that the boundary layers are unstable to disturbances to the vorticity component aligned with the across-isobath tidal velocity on extra-critical slopes. MDNs, trained on microstructure observations, are used to construct probabilistic finescale parameterization dependent on the finescale vertical kinetic energy (VKE), N2f2, , and both variables. The MDN model predictions are as accurate as conventional parameterizations, but also predict the underlying probability density function of the dissipation rate as a function of the dependent parameters.
    Description: My doctoral studies in the WHOI/MIT Joint Program were funded by the National Science Foundation (OCE-1657870) and the National Science Foundation Graduate Research Fellowship Program.
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 3
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2020.
    Description: Developing accurate and computationally efficient models for ocean acoustics is inherently challenging due to several factors including the complex physical processes and the need to provide results on a large range of scales. Furthermore, the ocean itself is an inherently dynamic environment within the multiple scales. Even if we could measure the exact properties at a specific instant, the ocean will continue to change in the smallest temporal scales, ever increasing the uncertainty in the ocean prediction. In this work, we explore ocean acoustic prediction from the basics of the wave equation and its derivation. We then explain the deterministic implementations of the Parabolic Equation, Ray Theory, and Level Sets methods for ocean acoustic computation. We investigate methods for evolving stochastic fields using direct Monte Carlo, Empirical Orthogonal Functions, and adaptive Dynamically Orthogonal (DO) differential equations. As we evaluate the potential of Reduced-Order Models for stochastic ocean acoustics prediction, for the first time, we derive and implement the stochastic DO differential equations for Ray Tracing (DO-Ray), starting from the differential equations of Ray theory. With a stochastic DO-Ray implementation, we can start from non-Gaussian environmental uncertainties and compute the stochastic acoustic ray fields in a reduced order fashion, all while preserving the complex statistics of the ocean environment and the nonlinear relations with stochastic ray tracing. We outline a deterministic Ray-Tracing model, validate our implementation, and perform Monte Carlo stochastic computation as a basis for comparison. We then present the stochastic DO-Ray methodology with detailed derivations. We develop varied algorithms and discuss implementation challenges and solutions, using again direct Monte Carlo for comparison. We apply the stochastic DO-Ray methodology to three idealized cases of stochastic sound-speed profiles (SSPs): constant-gradients, uncertain deep-sound channel, and a varied sonic layer depth. Through this implementation with non-Gaussian examples, we observe the ability to represent the stochastic ray trace field in a reduced order fashion.
    Description: Office of Naval Research Grants N00014-19-1-2664 (Task Force Ocean: DEEP-AI) and N00014-19-1-2693 (INBDA)
    Keywords: Stochastic Processes ; Acoustic Wave Propagation ; Acoustic Rays
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 4
    Publication Date: 2022-11-18
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Tian, Y., Liu, X., Li, J., Deng, Y., DeGiorgis, J. A., Zhou, S., Caratenuto, A., Minus, M. L., Wan, Y., Xiao, G., & Zheng, Y. Farm-waste-derived recyclable photothermal evaporator. Cell Reports Physical Science, 2(9), (2021): 100549, https://doi.org/10.1016./j.xcrp.2021.100549
    Description: Interfacial solar steam generation is emerging as a promising technique for efficient desalination. Although increasing efforts have been made, challenges exist for achieving a balance among a plethora of performance indicators—for example, rapid evaporation, durability, low-cost deployment, and salt rejection. Here, we demonstrate that carbonized manure can convert 98% of sunlight into heat, and the strong capillarity of porous carbon fibers networks pumps sufficient water to evaporation interfaces. Salt diffusion within microchannels enables quick salt drainage to the bulk seawater to prevent salt accumulation. With these advantages, this biomass-derived evaporator is demonstrated to feature a high evaporation rate of 2.81 kg m−2 h−1 under 1 sun with broad robustness to acidity and alkalinity. These advantages, together with facial deployment, offer an approach for converting farm waste to energy with high efficiency and easy implementation, which is particularly well suited for developing regions.
    Description: This project is supported by the National Science Foundation through grant no. CBET-1941743. This project is based upon work supported in part by the National Science Foundation under EPSCoR Cooperative Agreement no. OIA-1655221.
    Keywords: Biomass ; Recyclable ; Manure ; Farm waste ; Photothermal evaporation ; Desalination
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2022-10-27
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Meaders, J. L., de Matos, S. N., & Burgess, D. R. A pushing mechanism for microtubule aster positioning in a large cell type. Cell Reports, 33(1), (2020): 108213, doi:10.1016/j.celrep.2020.108213.
    Description: After fertilization, microtubule (MT) sperm asters undergo long-range migration to accurately position pronuclei. Due to the large sizes of zygotes, the forces driving aster migration are considered to be from pulling on the astral MTs by dynein, with no significant contribution from pushing forces. Here, we re-investigate the forces responsible for sperm aster centration in sea urchin zygotes. Our quantifications of aster geometry and MT density preclude a pulling mechanism. Manipulation of aster radial lengths and growth rates, combined with quantitative tracking of aster migration dynamics, indicates that aster migration is equal to the length of rear aster radii, supporting a pushing model for centration. We find that dynein inhibition causes an increase in aster migration rates. Finally, ablation of rear astral MTs halts migration, whereas front and side ablations do not. Collectively, our data indicate that a pushing mechanism can drive the migration of asters in a large cell type.
    Description: We would like to thank Dr. Jesse Gatlin for sending us the Tau-mCherry fusion protein for imaging live MTs. We would also like to thank Dr. Timothy Mitchison, Dr. Christine Field, and Dr. James Pelletier for supplying us with CA4, p150-CC1, and EB1-GFP peptides, as well as for fruitful discussions. Finally, we would like to thank Dr. Charles Shuster and Leslie Toledo-Jacobo for constructive feedback when preparing the manuscript. We thank Bret Judson and the Boston College Imaging Core for infrastructure and support. This material is based upon work supported by NSF grant no. 124425 to D.R.B.
    Keywords: Dynein ; Aster ; Microtubule ; Centrosome ; Pronucleus ; Fertilization ; Aster position
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
    Publication Date: 2022-10-27
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Stolp, Z. D., Kulkarni, M., Liu, Y., Zhu, C., Jalisi, A., Lin, S., Casadevall, A., Cunningham, K. W., Pineda, F. J., Teng, X., & Hardwick, J. M. Yeast cell death pathway requiring AP-3 vesicle trafficking leads to vacuole/lysosome membrane permeabilization. Cell Reports, 39(2), (2022): 110647, https://doi.org/10.1016/j.celrep.2022.110647.
    Description: Unicellular eukaryotes have been suggested as undergoing self-inflicted destruction. However, molecular details are sparse compared with the mechanisms of programmed/regulated cell death known for human cells and animal models. Here, we report a molecular cell death pathway in Saccharomyces cerevisiae leading to vacuole/lysosome membrane permeabilization. Following a transient cell death stimulus, yeast cells die slowly over several hours, consistent with an ongoing molecular dying process. A genome-wide screen for death-promoting factors identified all subunits of the AP-3 complex, a vesicle trafficking adapter known to transport and install newly synthesized proteins on the vacuole/lysosome membrane. To promote cell death, AP-3 requires its Arf1-GTPase-dependent vesicle trafficking function and the kinase Yck3, which is selectively transported to the vacuole membrane by AP-3. Video microscopy revealed a sequence of events where vacuole permeability precedes the loss of plasma membrane integrity. AP-3-dependent death appears to be conserved in the human pathogenic yeast Cryptococcus neoformans.
    Description: Funding sources: National Institutes of Health, United States grants AI144373 and NS127076 (J.M.H.), AI115016 and AI153414 (K.W.C.), and AI052733, AI152078, and HL059842 (A.C.); National Natural Science Foundation of China 31970550; and the Priority Academic Program Development of the Jiangsu Higher Education Institutes (X.T.).
    Keywords: Yeast ; Programmed cell death ; Vesicle trafficking ; AP-3 ; Vacuole ; Cryptococcus ; Yck3 ; Regulated cell death ; Lysosome ; Vacuolar membrane permeabilization
    Repository Name: Woods Hole Open Access Server
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  • 7
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Oceanography and Applied Ocean Science and Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2020.
    Description: The redox cycling of oxygen between O2, water, and intermediate redox states including hydrogen peroxide and superoxide, has profound impact on the availability and distribution of dissolved O2, the habitability of the marine biosphere, and cellular metabolic and physiological reactions that utilize O2. The sum total of processes that produce, consume, and exchange atoms with O2 in the atmosphere, oceans, and subsurface leave their isotopic fingerprints on the abundance of the three stable isotopes of O2 in the environment. In this thesis, I explore two aspects of the oxygen cycle in the past and present. First, I investigate the ability of manganese (Mn) oxide minerals to capture and retain the oxygen isotopic signature of dissolved O2 during the oxidation of aqueous Mn(II) to Mn-oxide minerals. I determine that approximately half of the oxygen atoms in Mn(III,IV) oxides are directly incorporated from dissolved oxygen, and use isotope labeling techniques to further constrain how the dissolved oxygen isotope signature may be determined from that of Mn oxides. I perform an in-depth characterization of a ferromanganese crust from the central Pacific and, using triple oxygen isotope measurements, demonstrate that Mn oxides in ferromanganese crusts from around the world retain signatures of dissolved oxygen for at least 30 million years. I next turn to a previously unconsidered aspect of the global oxygen cycle: dark, extracellular superoxide production by marine microbes. I measure extracellular superoxide production rates by some of the ocean’s most abundant organisms. I use these rates along with previous measurements to estimate that extracellular superoxide production yields a net sink of 5-19% of marine dissolved oxygen. Ultimately, the degree to which superoxide production is a sink of oxygen lies in the fate of its primary decay product, hydrogen peroxide. I determine the range of oxidative and reductive decay of hydrogen peroxide across a range of environmental conditions in a meromictic pond, thus validating several assumptions from our global estimate. Altogether, this thesis illuminates a path toward investigating the oxygen cycle on million-year timescales in Earth’s recent past and demonstrates the importance of microbial superoxide production in the biogeochemical cycling of O2.
    Description: This work was funded by the following grants and organizations: NASA Earth and Space Science Fellowship (NNX15AR62H), MIT Praecis Presidential Graduate Fellowship, NASA Exobiology (NNX15AM046), NSF-OCE grant 1355720, WHOI Ocean Ventures Fund, MIT Student Assistance Fund, WHOI Academic Programs Office, and the Stanford Synchrotron Radiation Lightsource. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DEAC02-76SF00515.
    Repository Name: Woods Hole Open Access Server
    Type: Thesis
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  • 8
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Oceanography and Microbial Biogeochemistry at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2020.
    Description: Marine microbes play key roles in global biogeochemistry by mediating chemical transformations and linking nutrient cycles to one another. A major goal in oceanography is to predict the activity of marine microbes across disparate ocean ecosystems. Towards this end, molecular biomarkers are important tools in chemical oceanography because they allow for both the observation and interpretation of microbial behavior. In this thesis, I use molecular biomarkers to develop a holistic, systems biology approach to the study of marine microbes. I begin by identifying unique patterns in the biochemical sensory systems of marine bacteria and suggest that these represent a specific adaptation to the marine environment. Building from this, I focus on the prevalent marine nitrogen fixer Trichodesmium, whose activity affects global nitrogen, carbon, phosphorus, and trace metal cycles. A metaproteomic survey of Trichodesmium populations identified simultaneous iron and phosphate co-stress throughout the tropical and subtropical oceans, demonstrating that this is caused by the biophysical limits of membrane space and nutrient diffusion. Tackling the problem at a smaller scale, I investigated the metaproteomes of individual Trichodesmium colonies captured from a single field site, and identified significant variability related to iron acquisition from mineral particles. Next, I investigated diel proteomes of cultured Trichodesmium erythraeum sp. IMS101 to highlight its physiological complexity and understand how and why nitrogen fixation occurs in the day, despite the incompatibly of the nitrogenase enzyme with oxygen produced in photosynthesis. This thesis develops a fundamental understanding of how Trichodesmium and other organisms affect, and are affected by, their surroundings. It indicates that a reductionist approach in which environmental drivers are considered independently may not capture the full complexity of microbechemistry interactions. Future work can focus on benchmarking and calibration of the protein biomarkers identified here, as well as continued connection of systems biology frameworks to the study of ocean chemistry.
    Description: This work was supported by an MIT Walter A. Rosenblith Presidential Fellowship and a National Science Foundation Graduate Research Program Fellowship under grant number 1122274 [N.Held]. This work was also supported by the WHOI Ocean Ventures fund [N.Held], Gordon and Betty Moore Foundation grant number 3782 [M.Saito], National Science Foundation grant numbers OCE-1657766 [M.Saito], EarthCube-1639714 [M.Saito], OCE-1658030 [M.Saito], and OCE-1260233 [M.Saito], and funding from the UK Natural Environment Research Council (NERC) under grants awarded to C.M. (NE/N001079/1) and M.L. (NE/N001125/1). This thesis was completed during a writing residency at the Turkeyland Cove Foundation.
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Submitted in partial fulfillment of the requirements for the degree of of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2020.
    Description: The shallow marine ecosystems of coral atolls and the human communities they support are among the most vulnerable to anthropogenic climate change. Sea-level rise threatens to inundate low-lying reef islands, tropical cyclone intensification threatens islands with flooding and erosion, and ocean warming and acidification threaten the health of coral reefs. Unfortunately, the sediment dynamics that shape the morphology of coral reefs and atoll reef islands are poorly understood, hindering predictions of coral atoll responses to climate change forcing. Here, I apply an eclectic set of methods, including numerical modeling, physical lab experiments, and sedimentological analysis, to produce insights into the ways tropical cyclones and waves move sediment on fringing reefs. First, I use a numerical model of hydrodynamics to predict the influence of sea-level rise and wave climate change on sediment transport across a coral atoll fringing reef. I demonstrate that by the end of the century, sea-level rise will reduce sediment transport rates from the fore reef to the beach, but increase transport rates from the reef flat to the beach. Wave climate change will have relatively negligible influence on cross-reef sediment transport. Additionally, I use the weathering of foraminifera tests to produce a sediment proxy of transport duration and direction across atoll reef flats, but demonstrate that the proxy does not clearly identify storm deposits. Second, I execute a series of experiments in an oscillating flow tunnel to constrain the rate at which sediment erodes reef surfaces under waves. I find that the erosion rate increases as a power law of wave orbital velocity, and that amount of sediment has a second-order influence. Finally, I establish grain size in a sediment core retrieved from a blue hole in the Marshall Islands as a proxy for tropical cyclone genesis and, using the results from an ensemble of climate models, demonstrate that enhanced tropical cyclogenesis during the Little Ice Age may have been driven by an anomalously negative Pacific Meridional Mode. This thesis demonstrates the importance of sediment dynamics on the morphology of fringing reefs and atoll reef islands and the sensitivity of those dynamics to centennial climate variability.
    Description: Funding for this project was provided by the Strategic Environmental Research and Development Program (SERDP RC-2336).
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2020.
    Description: Advances in the miniaturization of microelectronics has greatly contributed to the proliferation of small, low cost autonomous underwater vehicles (AUVs). These affordable vehicles offer organizations a flexible platform that can be adapted to support a multitude of research goals. The small size and low entry cost come with a trade off of simple navigation systems, typically dead reckoning (DR) using a speed determined via propeller counts and heading from a low cost micro-electromechanical system (MEMS) inertial measurement unit (IMU), whose error grows unbounded without the availability of a ground referenced fix source and is compounded by the bias present in the speed measurement due to the change in hydrodynamics from the addition of sensors to the hull form. Additionally, some capabilities such as water current velocity measurement traditionally requires the addition of equipment that is not only expensive, but also whose size and power consumption can adversely affect operating characteristics and deployment times. This thesis expands on previous research using one-way travel time inverted USBL (OWTT-iUSBL) to calculate the local current velocity without the addition of a Doppler velocity log (DVL) or acoustic Doppler current profiler (ADCP). A novel extended Kalman filter (EKF) is proposed that, in addition to calculating the current velocity, estimates and corrects for the bias present in the speed measurement as determined by the main vehicle computer. Using data collected on the Charles River at the Massachusetts Institute of Technology (MIT) Sailing Pavilion, it is shown that current velocities can be reasonably calculated using OWTT-iUSBL data as compared to the values calculated using long baseline (LBL) data.
    Description: Funding for this thesis research was provided the US Navy Civilian Institutions Office through the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program.
    Keywords: EKF ; low-cost ; AUV
    Repository Name: Woods Hole Open Access Server
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