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Reinforcement learning enabled automatic impedance control of a robotic knee prosthesis to mimic the intact knee motion in a co-adapting environment

arXiv

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arXiv 2021年

作者： Wu, Ruofan Li, Minhan Yao, Zhikai Si, Jennie Huang, He Department of Electrical Computer and Energy Engineering Arizona State University TempeAZ85287 United States Department of Biomedical Engineering North Carolina State University RaleighNC27695 United States University of North Carolina at Chapel Hill Chapel HillNC27599 United States

Automatically configuring a robotic prosthesis to fit its user’s needs and physical conditions is a great technical challenge and a roadblock to the adoption of the technology. Previously, we have successfully developed reinforcement learning (RL) solutions toward addressing this issue. Yet, our designs were based on using a subjectively prescribed target motion profile for the robotic knee during level ground walking. This is not realistic for different users and for different locomotion tasks. In this study for the first time, we investigated the feasibility of RL enabled automatic configuration of impedance parameter settings for a robotic knee to mimic the intact knee motion in a co-adapting environment. We successfully achieved such tracking control by an online policy iteration. We demonstrated our results in both OpenSim simulations and two able-bodied (AB) subjects. Copyright © 2021, The Authors. All rights reserved.

关键词： Reinforcement learning

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Unique material modifications of Ga2O3 enabled by ultrafast laser irradiation 11

Unique material modifications of Ga2O3 enabled by ultrafast ...

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Oxide-based Materials and Devices XI 2020

作者： Ahn, Minhyung Sarracino, Alex Ansari, Abdul Torralva, Ben Yalisove, Steven Phillips, Jamie Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Climate and Space Sciences and Engineering University of Michigan Ann ArborMI48109 United States Materials Science and Engineering Department University of Michigan Ann ArborMI48109 United States

ISBN: (纸本)9781510633254

Ultrafast (femtosecond pulse) laser irradiation provides unique laser-material interactions associated with high instantaneous electric fields and short timescales that lead to a nonequilibrium state between excited electrons and phonons. These interactions result in material modifications that differ from conventional chemical, physical, and thermal processing at much longer timescales, and an opportunity to address material and device processing challenges associated with wide-bandgap materials such as Ga2O3. In this work, we explore ultrafast laser irradiation (Ti:sapphire, 150 fs pulse width) of bulk (010) Sn-doped β-Ga2O3 under two different wavelengths, fundamental (780 nm) and frequency-doubled (390 nm), and a range of laser fluences. We identified a regime for laser-induced damage threshold resulting in material ablation, thermally-induced straight crack formation, and recrystallization. Rastering on a β-Ga2O3 substrate created surface nanostructures including laser-induced periodic surface structures at a high spatial frequency (period ∼250 nm). These highly aligned periodic structures can be controlled by laser polarization and wavelength, presenting a means for direct writing of surface nanostructures. Enhanced atomic movement associated with a transient metallic state can provide a means for intentional generation of point defects via the laser irradiation. These point defects may offer a means of electrical modification, which was demonstrated as more than five orders of the magnitude enhancement of lateral conductance on rastered β-Ga2O3. Moreover, a hydrophobic surface of β-Ga2O3was achieved by ultrafast laser irradiation. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Hydrophobicity

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Nanoparticle localization within chiral liquid crystal defect lines and nanoparticle interactions

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Physical Review E 2023年第3期107卷 034701-034701页

作者： Mykola Tasinkevych Sungoh Park Haridas Mundoor Ivan I. Smalyukh SOFT Group School of Science and Technology Nottingham Trent University Clifton Lane Nottingham NG11 8NS United Kingdom Departamento de Física and Centro de Física Teórica e Computacional Faculdade de Ciências Universidade de Lisboa 1749-016 Lisboa Portugal International Institute for Sustainability with Knotted Chiral Meta Matter Hiroshima University Higashihiroshima 739-8511 Japan Department of Physics University of Colorado Boulder Colorado 80309 USA Soft Materials Research Center Department of Electrical Computer and Energy Engineering and Materials Science and Engineering Program and Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado Boulder Colorado 80309 USA

Self-assembly of colloidal particles into predefined structures is a promising way to design inexpensive manmade materials with advanced macroscopic properties. Doping of nematic liquid crystals (LCs) with nanoparticles has a series of advantages in addressing these grand scientific and engineering challenges. It also provides a very rich soft matter platform for the discovery of unique condensed matter phases. The LC host naturally allows the realization of diverse anisotropic interparticle interactions, enriched by the spontaneous alignment of anisotropic particles due to the boundary conditions of the LC director. Here we demonstrate theoretically and experimentally that the ability of LC media to host topological defect lines can be used as a tool to probe the behavior of individual nanoparticles as well as effective interactions between them. LC defect lines irreversibly trap nanoparticles enabling controlled particle movement along the defect line with the use of a laser tweezer. Minimization of Landau–de Gennes free energy reveals a sensitivity of the ensuing effective nanoparticle interaction to the shape of the particle, surface anchoring strength, and temperature, which determine not only the strength of the interaction but also its repulsive or attractive character. Theoretical results are supported qualitatively by experimental observations. This work may pave the way toward designing controlled linear assemblies as well as one-dimensional crystals of nanoparticles such as gold nanorods or quantum dots with tunable interparticle spacing.

关键词： Charged colloids Complex fluids Liquid crystals

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Multi-Niche Human Bone Marrow On-a-Chip for Studying the Interactions of Adoptive Car-T Cell Therapies with Multiple Myeloma

SSRN

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SSRN 2024年

作者： Ghoshal, Delta Petersen, Ingrid Ringquist, Rachel Kramer, Liana Bhatia, Eshant Hu, Thomas Richard, Ariane Park, Reda Corbin, Jenna Agarwal, Savi Thomas, Abel Ramirez, Sebastian Tharayil, Jacob Downey, Emma Ketchum, Frank Ochal, Abigail Sonthi, Neha Lonial, Sagar Kochenderfer, James N. Tran, Reginald Zhu, Mandy Lam, Wilbur A. Coskun, Ahmet F. Roy, Krishnendu The Wallace H. Coulter Department of Biomedical Engineering Georgia Institute of Technology Emory University AtlantaGA30332 United States The Parker H. Petit Institute for Bioengineering & Bioscience Georgia Institute of Technology AtlantaGA30332 United States School of Chemical and Biomolecular Engineering Georgia Institute of Technology AtlantaGA30332 United States The George W. Woodruff Department of Mechanical Engineering Georgia Institute of Technology AtlantaGA30332 United States School of Electrical and Computer Engineering Georgia Institute of Technology AtlantaGA30332 United States Department of Biochemistry Georgia Institute of Technology AtlantaGA30332 United States Aerospace and Mechanical Engineering University of Notre Dame Notre DameIN46556 United States School of Biological Sciences Georgia Institute of Technology AtlantaGA30332 United States Department of Hematology and Medical Oncology Emory University School of Medicine AtlantaGA30322 United States Surgery Branch National Cancer Institute Bethesda MD20892 United States Division of Pediatric Hematology/Oncology Department of Pediatrics Aflac Cancer Center Blood Disorders Service of Children’s Healthcare of Atlanta Emory University School of Medicine AtlantaGA30322 United States School of Engineering Vanderbilt University NashvilleTN37235 United States

Multiple myeloma (MM), a cancer of bone marrow plasma cells, is the second-most common hematological malignancy. However, despite immunotherapies like chimeric antigen receptor (CAR)-T cells, relapse is nearly universal. The bone marrow (BM) microenvironment influences how MM cells survive, proliferate, and resist treatment. Yet, it is unclear which BM niches give rise to MM pathophysiology. Here, we present a 3D microvascularized culture system, which models the endosteal and perivascular bone marrow niches, allowing us to study MM-stroma interactions in the BM niche and model responses to therapeutic CAR-T cells. We demonstrated the prolonged survival of cell line-based and patient-derived multiple myeloma cells within our in vitro system and successfully perfused in donor-matched CAR-T cells. We then measured T cell survival, differentiation, and cytotoxicity against MM cells using a variety of analysis techniques. Our MM-on-a-chip system could elucidate the role of the BM microenvironment in MM survival and therapeutic evasion and inform the rational design of next-generation therapeutics. © 2024, The Authors. All rights reserved.

关键词： T-cells

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Digital filter effect of the ventilator tester parameters to identify inflation phases

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AIP Conference Proceedings 2022年第1期2537卷

作者： Tomy Abuzairi Ahli Irfan Basari 1Electrical Engineering Study Program Department of Electrical Engineering Faculty of Engineering Universitas Indonesia Kampus UI Depok West Java 16424 Indonesia 3Research Center for Biomedical Engineering Faculty of Engineering Universitas Indonesia Kampus UI Depok West Java 16424 Indonesia 2Biomedical Engineering Study Program Department of Electrical Engineering Faculty of Engineering Universitas Indonesia Kampus UI Depok West Java 16424 Indonesia

A ventilator is a breathing support device that serves as a therapeutic tool or treatment tool for patients with respiratory system failure caused by various health problems or diseases. On ventilators, there are crucial parameters that need to be monitored in advance, such as inspiration–expiration (I:E) ratio, respiration rate, tidal volume, peak inspiration pressure (PIP), positive end-expiratory pressure (PEEP), and oxygen concentration. To monitor those parameters, a ventilator tester is needed. In this paper, we analyzed the effect of a digital filter in the ventilator tester, COVENT-Tester, to identify the inflation phase in the ventilator parameters. The results show that the digital filter is not effective in measuring I:E ratio and respiration rate because of the delay in inspiration and expiration time. However, the digital filter is effective in measuring tidal volume, PIP, PEEP, and oxygen concentration.

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Re-identification of Individuals in Genomic Datasets Using Public Face Images

arXiv

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arXiv 2021年

作者： Venkatesaramani, Rajagopal Malin, Bradley A. Vorobeychik, Yevgeniy Washington University in St. Louis Department of Computer Science and Engineering St. Louis63130 United States Vanderbilt University Department of Electrical Engineering and Computer Science Nashville37232 United States Vanderbilt University Medical Center Department of Biomedical Informatics Nashville37203 United States Vanderbilt University Medical Center Department of Biostatistics Nashville37203 United States

DNA sequencing is becoming increasingly commonplace, both in medical and direct-to-consumer settings. To promote discovery, collected genomic data is often de-identified and shared, either in public repositories, such as OpenSNP, or with researchers through access-controlled repositories. However, recent studies have suggested that genomic data can be effectively matched to high-resolution three-dimensional face images, which raises a concern that the increasingly ubiquitous public face images can be linked to shared genomic data, thereby re-identifying individuals in the genomic data. While these investigations illustrate the possibility of such an attack, they assume that those performing the linkage have access to extremely well-curated data. Given that this is unlikely to be the case in practice, it calls into question the pragmatic nature of the attack. As such, we systematically study this re-identification risk from two perspectives: first, we investigate how successful such linkage attacks can be when real face images are used, and second, we consider how we can empower individuals to have better control over the associated re-identification risk. We observe that the true risk of re-identification is likely substantially smaller for most individuals than prior literature suggests. In addition, we demonstrate that the addition of a small amount of carefully crafted noise to images can enable a controlled trade-off between re-identification success and the quality of shared images, with risk typically significantly lowered even with noise that is imperceptible to humans. © 2021, CC BY.

关键词： DNA sequences

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A microfluidic method for creating poly(Ethylene glycol) gradient microgel scaffolds to modulate human mesenchymal stem cell behavior 42

A microfluidic method for creating poly(Ethylene glycol) gra...

引用

42nd Society for Biomaterials Annual Meeting and Exposition 2019: The Pinnacle of Biomaterials Innovation and Excellence

作者： Xin, Shangjing Dai, Jing Han, Arum Alge, Daniel Department of Biomedical Engineering Texas A&M University United States Department of Electrical and Computer Engineering Texas A&M University United States

ISBN: (纸本)9781510883901

Statement of Purpose: Stem cell fate is influenced by the biochemical and biophysical cues presented by the extracellular matrix (ECM), and there is high interest in developing tissue engineering scaffolds with controlled heterogeneity to direct stem cell behavior. Assembling microgels into 3D tissue engineering scaffolds is a unique approach to address this challenge, as one key advantage is that this bottom-up strategy allows the incorporation of multiple formulations of microgels to generate spatial patterning of physicochemical properties. Random distributions or zones of distinct microgels in a single scaffold have been explored as injectable hydrogel systems. Here, we developed a microfluidic method to create poly(ethylene glycol) (PEG) gradient microgel scaffolds by tuning the flow rates of two gel components, with the objective of modulating human mesenchymal stem cell (hMSC) behaviors by presenting physicochemical gradients in these scaffolds. © 2019 Omnipress - All rights reserved.

关键词： Stem cells

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Technological enhancements in personalized dietary management for chronic conditions

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biomedical engineering Advances 2025年 10卷

作者： Tania Tahtouh Hadil Salman Nermin Eissa Najla Al Nassar Sofyan Maghaydah Marah Alhalabi Maha Yaghi Abdalla Gad Dana Abdallah Salma Elberry Aysha Alhosani Shaikha Alshehhi Mohammad Alkhedher Mohamad Ramadan Mohammed Ghazal Health Sciences Department Abu Dhabi University Abu Dhabi 59911 United Arab Emirates Electrical Computer and Biomedical Engineering Department Abu Dhabi University Abu Dhabi 59911 United Arab Emirates Department of Mechanical Engineering Abu Dhabi University Abu Dhabi 59911 United Arab Emirates School of Engineering International University of Beirut Beirut 146404 Lebanon

Dietary compliance plays a vital role in the control of chronic diseases and influences response to therapy. The rapid development experienced nowadays through smart technology has enabled the personalization of dietary advice to meet individual needs. This paper provides an overview of the current technological solutions to dietary adherence among patients with chronic conditions. With the increasing prevalence of chronic diseases requiring diet-specific interventions, this review encompasses mobile apps and wearables to IoT-based devices and generative intelligence tools, including chatbots, aimed at offering specific guidance as well as providing individualized support for dietary requirements. This review provides an overview of the strengths and limitations of these approaches in real world applications, as well as emerging methodologies that attempt to improve this by focusing on means to personalize dietary management more effectively. The study suggests that technology-enabled dietary interventions can be useful to support chronic disease management and generative artificial intelligence may have a profound effect on the further personalization of dietary guidance. However, issues surrounding regulatory alignment, content validity and long-term user engagement remain to be resolved in order to maximize the tools’ functionality in clinical and home settings.

关键词： Dietary management Chronic conditions mHealth Personalized health Artificial intelligence Smart technology

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Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch

arXiv

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arXiv 2024年

作者： Kopas, Cameron J. Goronzy, Dominic P. Pham, Thang Torres Castanedo, Carlos G. Cheng, Matthew Cochrane, Rory Nast, Patrick Lachman, Ella Zhelev, Nikolay Z. Vallières, André Murthy, Akshay A. Oh, Jin-Su Zhou, Lin Kramer, Matthew J. Cansizoglu, Hilal Bedzyk, Michael J. Dravid, Vinayak P. Romanenko, Alexander Grassellino, Anna Mutus, Josh Y. Hersam, Mark C. Yadavalli, Kameshwar Rigetti Computing BerkeleyCA United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States Center for Applied Physics and Superconducting Technologies Northwestern University EvanstonIL United States Department of Physics and Astronomy Northwestern University EvanstonIL United States Department of Physics University of Oregon EugeneOR United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Fermi National Accelerator Laboratory BataviaIL United States Ames Laboratory U.S. Department of Energy AmesIA United States Northwestern University EvanstonIL United States Department of Chemistry Northwestern University EvanstonIL United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL United States

The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposure. Here, we explore a novel wet chemical surface treatment at the Josephson junction-substrate and the substrate-air interfaces by replacing a buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed by aqueous ammonium fluoride. We show that the ammonium fluoride etch process results in a statistically significant improvement in median T1 by ∼ 22% (p = 0.002), and a reduction in the number of strongly-coupled TLS in the tunable frequency range. Microwave resonator measurements on samples treated with the ammonium fluoride etch prior to niobium deposition also show ∼ 33% lower TLS-induced loss tangent compared to the BOE treated samples. As the chemical treatment primarily modifies the Josephson junction-substrate interface and substrate-air interface, we perform targeted chemical and structural characterizations to examine materials’ differences at these interfaces and identify multiple microscopic changes that could contribute to decreased TLS. © 2024, CC BY-NC-ND.

关键词： Fluorine compounds

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Overcoming the fundamental limit of two-photon microscopy with non-degenerate excitation

Overcoming the fundamental limit of two-photon microscopy wi...

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Optics and the Brain, BRAIN 2020

作者： Sadegh, Sanaz Yang, Mu-Han Cheng, Xiaojun Thunemann, Martin Saisan, Payam A. Boas, David A. Fainman, Yeshaiahu Devor, Anna Department of Neurosciences University of California San DiegoCA92093 United States Department of Electrical and Computer Engineering University of California San DiegoCA92093 United States Department of Biomedical Engineering Boston University MA02215 United States Department of Radiology University of California San DiegoCA92093 United States Martinos Center for Biomedical Imaging MGH Harvard Medical School CharlestownMA02129 United States

We use non-degenerate two-photon excitation where the two excitation beams are displaced in space outside the focal volume to increase the signal-to-background ratio (SBR), overcoming the fundamental penetration depth... 详细信息

ISBN: (纸本)9781943580743

关键词： Photons

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