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- Creator:
- Burgin, Tucker and Mayes, Heather B.
- Description:
- This project aimed to discover and analyze the molecular mechanism of synthesis of two particular fucosylated oligosaccharide products in a mutant enzyme, Thermatoga maratima Alpha-L-Fucosidase D224G, whose wild type performs the opposite reaction (cleavage of fucosyl glycosidic bonds). Discovery of the mechanism was performed using an unbiased simulations method known as aimless shooting, whereas analysis of the mechanism in terms of the energy profile was performed using a separate method known as equilibrium path sampling. The data here concerns the latter method. and The contents of the atesa_master.zip are the ATESA GitHub project. A Python program for automating transition path sampling with aimless shooting using Amber. https://github.com/team-mayes/atesa
- Keyword:
- Equilibrium Path Sampling, Transition Path Sampling, Enzymatic Mechanism, and GH29
- Citation to related publication:
- Burgin, T., & Mayes, H. B. (2019). Mechanism of oligosaccharide synthesis via a mutant GH29 fucosidase. Reaction Chemistry & Engineering, 4(2), 402–409. https://doi.org/10.1039/C8RE00240A
- Discipline:
- Engineering
-
- Creator:
- Ruas, Terry, Ferreira, Charles H. P., Grosky, William, França, Fabrício O., and Medeiros, Débora M. R,
- Description:
- The relationship between words in a sentence often tell us more about the underlying semantic content of a document than its actual words, individually. Recent publications in the natural language processing arena, more specifically using word embeddings, try to incorporate semantic aspects into their word vector representation by considering the context of words and how they are distributed in a document collection. In this work, we propose two novel algorithms, called Flexible Lexical Chain II and Fixed Lexical Chain II that combine the semantic relations derived from lexical chains, prior knowledge from lexical databases, and the robustness of the distributional hypothesis in word embeddings into a single decoupled system. In short, our approach has three main contributions: (i) unsupervised techniques that fully integrate word embeddings and lexical chains; (ii) a more solid semantic representation that considers the latent relation between words in a document; and (iii) lightweight word embeddings models that can be extended to any natural language task. Knowledge-based systems that use natural language text can benefit from our approach to mitigate ambiguous semantic representations provided by traditional statistical approaches. The proposed techniques are tested against seven word embeddings algorithms using five different machine learning classifiers over six scenarios in the document classification task. Our results show that the integration between lexical chains and word embeddings representations sustain state-of-the-art results, even against more complex systems. Github: https://github.com/truas/LexicalChain_Builder
- Keyword:
- document classification, lexical chains, word embeddings, synset embeddings, chain2vec, and natural language processing
- Citation to related publication:
- Terry Ruas, Charles Henrique Porto Ferreira, William Grosky, Fabrício Olivetti de França, Débora Maria Rossi de Medeiros, "Enhanced word embeddings using multi-semantic representation through lexical chains", Information Sciences, 2020, https://doi.org/10.1016/j.ins.2020.04.048
- Discipline:
- Other, Science, and Engineering
-
- Creator:
- Whittaker, Collin B.
- Description:
- This study follows after work conducted first for my dissertation and is presently being prepared for journal submission. The goal of our analysis was to analyze a small design space for an electrospray array thruster---varying the geometry of its emitters, the size of its extractor apertures, and its operating voltage---to determine designs robust to uncertainty. That is, we use a model for array performance whose input parameters we treat as uncertain (stemming from approximations to higher-order physics, manufacturing tolerances in fabricating a thruster, and so on). Making these predictions as a function of design, then, we can identify configurations that are performant robust to this uncertainty (i.e., still meet required performance specifications with high confidence). The data which inform this trade study are taken pricipally from our pending manuscript "Emitter Model Inference from Electrospray Array Thruster Tests", and from my thesis, "Designing Porous Electrospray Array Thrusters Under Uncertainty" (linked to the dataset as published). The analysis was conducted in January and February of 2025. This work was supported by a NASA Space Technology Graduate Research Opportunity (80NSSC21K1247). This research was also supported in part through computational resources and services provided by Advanced Research Computing, a division of Information and Technology Services at the University of Michigan, Ann Arbor.
- Keyword:
- Electrospray, Electric propulsion, Robust optimization, Bayesian inference, and Ionic liquid ion source
- Discipline:
- Engineering
-
- Creator:
- Whittaker, Collin B
- Description:
- The object of our study was to train a reduced-fidelity model for individual emitter behavior within a porous conical type electrospray array thruster on data taken over the entire array, which is the sum over all the emitters. By leveraging surface profilometry to measure the variance in geometry in the array, we then gain insight into the individual emitter dynamics. By rigorously predicating uncertainty in the predictions made by the model on uncertainty over its inputs, we can then understand the major sources of uncertainty in the system. The raw experimental data which inform this inference and prediction study were acquired in April of 2024 at the Jet Propulsion Laboratory's MicroPropulsion Laboratory, with special thanks to Colleen Marrese-Reading and Steven Arestie. These and other results are reported in a separate manuscript: C. B. Whittaker, B. A. Jorns, S. M. Arestie, and C. M. Marrese-Reading, in 38th International Electric Propulsion Conference (Electric Rocket Propulsion Society, 2024) p. 730. The thruster used in these experiments was fabricated at the University of Michigan in March of 2024. The analysis underlying this work was conducted from September of 2024 to January of 2025. This work was supported by a NASA Space Technology Graduate Research Opportunity (80NSSC21K1247). This research was also supported in part through computational resources and services provided by Advanced Research Computing, a division of Information and Technology Services at the University of Michigan, Ann Arbor. Finally, this work was performed in part at the University of Michigan Lurie Nanofabrication Facility.
- Keyword:
- Electrospray, Electric propulsion, Ionic liquid ion source, Bayesian inference, and Profilometry
- Discipline:
- Engineering
-
- Creator:
- Chen, Hongfan, Chen, Yang, Huang, Zhenguang, Zou, Shasha, Huan, Xun, and Toth, Gabor
- Description:
- Accurately predicting the horizontal component of the ground magnetic field perturbation (dBH), which can be used to calculate the Geomagnetically Induced Currents (GICs), is crucial for estimating the space weather impact of geomagnetic disturbances. In this work, we develop a new data-driven model GeoDGP using deep Gaussian process (DGP), which is a Bayesian non-parametric approach. The model provides global probabilistic forecasts of dBH at 1-minute time cadence and with arbitrary spatial resolutions. We evaluate the model comprehensively on a wide range of geomagnetic storms, including the 2024 Gannon extreme storm. The results show that GeoDGP significantly outperforms the state-of-the-art physics-based first-principles Space Weather Modeling Framework (SWMF) Michigan Geospace model and the data-driven DAGGER model.
- Keyword:
- Space Weather, Uncertainty Quantification, Machine Learning, and Bayesian Inference
- Citation to related publication:
- Chen, H., et al. (2024). GeoDGP: One-Hour Ahead Global Probabilistic Geomagnetic Perturbation Forecasting using Deep Gaussian Process.
- Discipline:
- Science and Engineering
-
- Creator:
- Chen, Hongfan, Sachdeva, Nishtha, Huang, Zhenguang, van der Holst, Bart, Manchester, Ward, Jivani, Aniket, Zou, Shasha, Chen, Yang, Huan, Xun, and Toth, Gabor
- Description:
- In this study, we show that coronal mass ejection (CME) simulations conducted with the Space Weather Modeling Framework (SWMF) can be assimilated with SOHO LASCO white-light (WL) coronagraph observations and solar wind observations at L1 prior to the CME eruption to improve the prediction of CME arrival time. L1 observations are used to constrain the background solar wind, while LASCO coronagraph observations filter the initial ensemble simulations by constraining the simulated CME propagation speed. We then construct probabilistic predictions for CME arrival time using the data-assimilated ensemble. Scripts in this work are written in R, Python and Julia.
- Keyword:
- Data Assimilation, Uncertainty Quantification, and Space Weather
- Citation to related publication:
- https://doi.org/10.1029/2024SW004165
- Discipline:
- Engineering
-
- Creator:
- Bu, Xiangyun, Geng, Yihao, Yin, Siyuan, Luo, Liyan, Aubin, Cameron A., and Moore, Talia Y.
- Description:
- Suction is a useful strategy to grasp objects or anchor a body, especially when prolonged contact is desired. For passive suction cups, detachment requires manual delamination, which cannot occur autonomously. Active suction cups detach via equalizing pressure in the suction cavity with the surrounding environment, either by adding fluid (e.g., from a compressed air source) or reducing the cavity volume. While this detachment mechanism can be autonomous, it is inefficient, resulting in a net zero or loss of fluid. A more efficient detachment mechanism would enable multiple iterations of attachment and detachment without requiring additional fluid. To address this need, we designed a suction cup with a secondary release chamber embedded in the contact ring. The release chamber triggers delamination by deforming the shape of the contact ring. Through empirical testing, we found the optimal location and geometry of the release chamber. Our design allows for reliable detachment with a 5~mL decrease in release chamber volume, regardless of the adhesive suction force. Because the release chamber is a closed system, attachment and detachment results in net gain of fluid. Therefore, we propose a novel secondary benefit of adhesion via suction: harvesting fluid to power other pressure-driven soft robotic systems. and This ZIP archive includes CAD models for: The exploded view of the suction cup assembly and the molds of all suction cup configurations shown in Figure 4 of the paper: (b) Different release chamber locations (c) Different membrane thicknesses (d) Constant volume with varying release chamber areas (e) Constant area with varying release chamber heights (f) Constant height with varying release chamber areas
- Keyword:
- suction, adhesion, energy harvesting, and soft robotics
- Citation to related publication:
- Xiangyun Bu, Yihao Geng, Siyuan Yin, Liyan Luo, Cameron A. Aubin, Talia Y. Moore (2025) "Release Chamber Enables Suction Cup to Delaminate and Harvest Fluid" IEEE RoboSoft.
- Discipline:
- Engineering
-
- Creator:
- Bealer, Elizabeth, Padgaonkar, Namit, Crumley, Kelly, Saito, Eiji, Beekman, Zoe, DeKorte, Alexa, Prakash, Thazha P, Revenko, Alexey, and Shea, Lonnie D.
- Description:
- Herein, we investigate the development of anti-TNFα antisense oligonucleotide conjugated PLG nanoparticles (PLG-aTNFα) as an anti-inflammatory therapy after stem cell derived islet transplantation. PLG-aTNFα NPs are shelf stable and successfully reduce TNFα secretion and expression in inflammatory macrophages. Synergy between the aTNFα ASO and the PLG NPs results in further knockdown of IL-1β, IL-6, iNOS, and IL-12 in vitro indicating PLG-aTNFα NPs may protect against the inflammatory cascade in vivo. In a diabetic mouse model, SC islets transplanted to the peritoneal fat were protected after treatment with PLG-aTNFα NPs compared PLG NPs alone. TNFα and IL-1β expression was reduced in mice treated with PLG-aTNFα NPs indicating inflammation was reduced after transplant. PLG-aTNFα NPs reduce TNFα and protect islets, supporting their potential use a therapeutic in islet transplantation.
- Keyword:
- Antisense oligonucleotide, TNFα, SC islets, Inflammation, and Cell transplant
- Discipline:
- Engineering
-
- Creator:
- Nunley, Hayden, Xue, Xufeng, Sun, Yubing, Resto-Irizarry, Agnes M, Yuan, Ye, Yong, Koh Meng Aw, Zheng, Yi, Weng, Shinuo, Shao, Yue, Lubensky, David K, Studer, Lorenz, and Fu, Jianping
- Description:
- Studies of fate patterning during development typically emphasize cell-cell communication via diffusible chemical signals. Recent experiments on stem cell colonies (see Xue et al. Nature Materials 2018), however, suggest that in some cases mechanical stresses, rather than secreted chemicals, enable long-ranged cell-cell interactions that specify positional information and pattern cell fates. The authors of this earlier publication reported a set of in vitro experiments in which uniformly supplied chemical media induced spatially patterned fates in cell colony in a disc geometry. They provided significant evidence that inter-cellular mechanical interactions, as well as mechanical interactions between cells and the substrate, play an important role in this in vitro differentiation process. As part of these experiments, they showed that the concentric width of the outer fate domain is approximately constant as the colony diameter is increased from 300 um to 800 um. In this subsequent publication, we propose a mathematical model for this fate patterning process and explore how the fate pattern depends on substrate stiffness. The experimental images of cell colonies, both for varying cell colony diameter (from Xue et al. Nature Materials 2018) and for varying substrate stiffness (data generated for the publication linked to these data), are provided here. Each example has an image for PAX3 signal (marker for outer fate domain; Paired box gene 3) and an image for DAPI signal (staining nuclei; 4′,6-diamidino-2-phenylindole).
- Keyword:
- Biomechanics, Cell communication, Cell mechanics, Developmental pattern formation, Force sensing, and Vertebrate development
- Citation to related publication:
- Nunley H, Xue X, Fu, J, Lubensky, DK. Generation of fate patterns via intercellular forces. BioRxiv 442205 [Preprint]. April 30, 2021 [cited 2025 Feb 20]. Available from: doi: https://doi.org/10.1101/2021.04.30.442205 and Xue X, Sun Y, Resto-Irizarry A.M. et al. Mechanics-guided embryonic patterning of neuroectoderm tissue from human pluripotent stem cells. Nature Mater 17, 633–641 (2018). https://doi.org/10.1038/s41563-018-0082-9
- Discipline:
- Science and Engineering
-
- Creator:
- Nunley, Hayden and Lubensky, David K
- Description:
- In a previous study (Xue et al. Nature Materials 2018), the authors showed that a key fate patterning event in vertebrate development can be reproduced in an in vitro stem cell culture. They further showed that this in vitro fate pattern seems to depend on mechanical signals rather than secreted chemical signals. In this follow-up study, a mathematical model of this process is proposed. The code in this deposit is for the simulation of this mathematical model in various cell layer geometries and substrate geometries. These geometries include a 1D cell layer, quasi-1D stripe geometry, disc geometry (all on a very thin substrate or a substrate composed of microposts) as well as a 1D cell layer on a finite-thickness substrate. Our model implies that the width of the outer fate domain varies non-monotonically with substrate stiffness, a prediction that we confirm experimentally.
- Keyword:
- Biomechanics, Cell communication, Cell mechanics, Developmental pattern formation, and Force sensing
- Citation to related publication:
- Nunley H, Xue X, Fu, J, Lubensky, DK. Generation of fate patterns via intercellular forces. BioRxiv 442205 [Preprint]. April 30, 2021 [cited 2025 Feb 20]. Available from: doi: https://doi.org/10.1101/2021.04.30.442205, Xue X, Sun Y, Resto-Irizarry A.M. et al. Mechanics-guided embryonic patterning of neuroectoderm tissue from human pluripotent stem cells. Nature Mater 17, 633–641 (2018). https://doi.org/10.1038/s41563-018-0082-9, Banerjee S, Marchetti MC. Substrate rigidity deforms and polarizes active gels. EPL (Europhysics Letters) 96, 28003 (2011). https://doi.org/10.1209/0295-5075/96/28003, Edwards CM, Schwarz US. Force Localization in Contracting Cell Layers, Physical Review Letters 107, 128101 (2011). https://doi.org/10.1103/PhysRevLett.107.128101, and Banerjee S, Marchetti MC. Contractile Stresses in Cohesive Cell Layers on Finite-Thickness Substrates, Physical Review Letters 109, 108101 (2012). https://doi.org/10.1103/PhysRevLett.109.108101
- Discipline:
- Engineering and Science