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  1. Article ; Online: Hierarchical Optimization for Control of Robotic Knee Prostheses Toward Improved Symmetry of Propulsive Impulse.

    Li, Minhan / Liu, Wentao / Si, Jennie / Stallrich, Jonathan W / Huang, He

    IEEE transactions on bio-medical engineering

    2023  Volume 70, Issue 5, Page(s) 1634–1642

    Abstract: Automatically personalizing complex control of robotic prostheses to improve gait performance, such as gait symmetry, is challenging. Recently, human-in-the-loop (HIL) optimization and reinforcement learning (RL) have shown promise in achieving optimized ...

    Abstract Automatically personalizing complex control of robotic prostheses to improve gait performance, such as gait symmetry, is challenging. Recently, human-in-the-loop (HIL) optimization and reinforcement learning (RL) have shown promise in achieving optimized control of wearable robots for each individual user. However, HIL optimization methods lack scalability for high-dimensional space, while RL has mostly focused on optimizing robot kinematic performance. Thus, we propose a novel hierarchical framework to personalize robotic knee prosthesis control and improve overall gait performance. Specifically, in this study the framework was implemented to simultaneously design target knee kinematics and tune 12 impedance control parameters for improved symmetry of propulsive impulse in walking. In our proposed framework, HIL optimization is used to identify an optimal target knee kinematics with respect to symmetry improvement, while RL is leveraged to yield an optimal policy for tuning impedance parameters in high-dimensional space to match the kinematics target. The proposed framework was validated on human subjects, walking with robotic knee prosthesis. The results showed that our design successfully shaped the target knee kinematics as well as configured 12 impedance control parameters to improve propulsive impulse symmetry of the human users. The knee kinematics that yielded best propulsion symmetry did not preserve the normative knee kinematics profile observed in non-disabled individuals, suggesting that restoration of normative joint biomechanics in walking does not necessarily optimize the gait performance of human-prosthesis systems. This new framework for prosthesis control personalization may be extended to other wearable devices or different gait performance optimization goals in the future.
    MeSH term(s) Humans ; Knee Prosthesis ; Robotics ; Robotic Surgical Procedures ; Gait ; Walking ; Knee Joint/surgery ; Biomechanical Phenomena
    Language English
    Publishing date 2023-04-20
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 160429-6
    ISSN 1558-2531 ; 0018-9294
    ISSN (online) 1558-2531
    ISSN 0018-9294
    DOI 10.1109/TBME.2022.3224026
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Mixture designs to investigate adverse effects upon co-exposure to environmental cyanotoxins.

    Martin, Rubia M / Stallrich, Jonathan / Bereman, Michael S

    Toxicology

    2019  Volume 421, Page(s) 74–83

    Abstract: The goal of this study was to implement powerful mixture design techniques, commonly used in process optimization, to investigate enhanced adverse effects upon co-exposure to environmental cyanotoxins. Exposure to cyanobacteria, which are found ... ...

    Abstract The goal of this study was to implement powerful mixture design techniques, commonly used in process optimization, to investigate enhanced adverse effects upon co-exposure to environmental cyanotoxins. Exposure to cyanobacteria, which are found ubiquitously in environmental water reservoirs, have been linked to several neurodegenerative diseases. Despite the known co-occurrence of various cyanotoxins, the majority of studies investigating this link have focused on the investigation of a single cyanotoxin, a noncanonical amino acid called β-methylamino-L-alanine (BMAA), which poorly recapitulates an actual environmental exposure. Interactions amongst cyanotoxic compounds is an area of great concern and remains poorly understood. To this end, we describe the use of a simplex axial mixture design to screen for interactive adverse effects of cyanotoxic mixtures. Using a combination of basic toxicity assays coupled with contemporary proteomic techniques, our results show the existence of a significant (p ≤ 0.01) interaction between BMAA and its isomers aminoethyl glycine (AEG) and 2,4-diaminobutyric acid (2,4DAB). Cyanotoxic mixtures significantly decreased cell viability by an average of 19% and increased caspases 3/7 activities by an average of 110% when compared to individual cyanotoxins (p ≤ 0.05). Cyanotoxic mixtures perturbed various biological pathways associated with neurodegeneration, including inhibition of protective autophagy and activation of mitochondrial dysfunction (z-score >|2|). Additionally, exposure to mixtures perturbed important upstream regulators involved in cellular dysfunction, morbidity, and development. Taken together, our results highlight: (1) the need to study combinations of cyanotoxins when investigating the link between cyanobacteria and neurodegenerative pathologies and (2) the application of design of experiment (DoE) as an efficient methodology to study mixtures of relevant environmental toxins.
    MeSH term(s) Animals ; Bacterial Toxins/toxicity ; Cell Line ; Cell Survival/drug effects ; Cyanobacteria ; Drug Interactions ; Mice ; No-Observed-Adverse-Effect Level ; Proteome/drug effects ; Risk Assessment/methods ; Toxicity Tests/methods
    Chemical Substances Bacterial Toxins ; Proteome
    Language English
    Publishing date 2019-04-25
    Publishing country Ireland
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 184557-3
    ISSN 1879-3185 ; 0300-483X
    ISSN (online) 1879-3185
    ISSN 0300-483X
    DOI 10.1016/j.tox.2019.04.013
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Mixture designs to investigate adverse effects upon co-exposure to environmental cyanotoxins

    Martin, Rubia M / Bereman, Michael S / Stallrich, Jonathan

    Toxicology. 2019 June 01, v. 421

    2019  

    Abstract: The goal of this study was to implement powerful mixture design techniques, commonly used in process optimization, to investigate enhanced adverse effects upon co-exposure to environmental cyanotoxins. Exposure to cyanobacteria, which are found ... ...

    Abstract The goal of this study was to implement powerful mixture design techniques, commonly used in process optimization, to investigate enhanced adverse effects upon co-exposure to environmental cyanotoxins. Exposure to cyanobacteria, which are found ubiquitously in environmental water reservoirs, have been linked to several neurodegenerative diseases. Despite the known co-occurrence of various cyanotoxins, the majority of studies investigating this link have focused on the investigation of a single cyanotoxin, a noncanonical amino acid called β-methylamino-L-alanine (BMAA), which poorly recapitulates an actual environmental exposure. Interactions amongst cyanotoxic compounds is an area of great concern and remains poorly understood. To this end, we describe the use of a simplex axial mixture design to screen for interactive adverse effects of cyanotoxic mixtures. Using a combination of basic toxicity assays coupled with contemporary proteomic techniques, our results show the existence of a significant (p ≤ 0.01) interaction between BMAA and its isomers aminoethyl glycine (AEG) and 2,4-diaminobutyric acid (2,4DAB). Cyanotoxic mixtures significantly decreased cell viability by an average of 19% and increased caspases 3/7 activities by an average of 110% when compared to individual cyanotoxins (p ≤ 0.05). Cyanotoxic mixtures perturbed various biological pathways associated with neurodegeneration, including inhibition of protective autophagy and activation of mitochondrial dysfunction (z-score >|2|). Additionally, exposure to mixtures perturbed important upstream regulators involved in cellular dysfunction, morbidity, and development. Taken together, our results highlight: (1) the need to study combinations of cyanotoxins when investigating the link between cyanobacteria and neurodegenerative pathologies and (2) the application of design of experiment (DoE) as an efficient methodology to study mixtures of relevant environmental toxins.
    Keywords adverse effects ; amino acids ; autophagy ; caspases ; cell viability ; Cyanobacteria ; cyanobacterial toxins ; environmental exposure ; isomers ; mitochondria ; morbidity ; neurodegenerative diseases ; proteomics ; toxicity ; water reservoirs
    Language English
    Dates of publication 2019-0601
    Size p. 74-83.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 184557-3
    ISSN 1879-3185 ; 0300-483X
    ISSN (online) 1879-3185
    ISSN 0300-483X
    DOI 10.1016/j.tox.2019.04.013
    Database NAL-Catalogue (AGRICOLA)

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  4. Book ; Online: Statistical Challenges in Online Controlled Experiments

    Larsen, Nicholas / Stallrich, Jonathan / Sengupta, Srijan / Deng, Alex / Kohavi, Ron / Stevens, Nathaniel

    A Review of A/B Testing Methodology

    2022  

    Abstract: The rise of internet-based services and products in the late 1990's brought about an unprecedented opportunity for online businesses to engage in large scale data-driven decision making. Over the past two decades, organizations such as Airbnb, Alibaba, ... ...

    Abstract The rise of internet-based services and products in the late 1990's brought about an unprecedented opportunity for online businesses to engage in large scale data-driven decision making. Over the past two decades, organizations such as Airbnb, Alibaba, Amazon, Baidu, Booking, Alphabet's Google, LinkedIn, Lyft, Meta's Facebook, Microsoft, Netflix, Twitter, Uber, and Yandex have invested tremendous resources in online controlled experiments (OCEs) to assess the impact of innovation on their customers and businesses. Running OCEs at scale has presented a host of challenges requiring solutions from many domains. In this paper we review challenges that require new statistical methodologies to address them. In particular, we discuss the practice and culture of online experimentation, as well as its statistics literature, placing the current methodologies within their relevant statistical lineages and providing illustrative examples of OCE applications. Our goal is to raise academic statisticians' awareness of these new research opportunities to increase collaboration between academia and the online industry.
    Keywords Statistics - Applications
    Subject code 306
    Publishing date 2022-12-21
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Effects of extended powered knee prosthesis stance time via visual feedback on gait symmetry of individuals with unilateral amputation: a preliminary study.

    Brandt, Andrea / Riddick, William / Stallrich, Jonathan / Lewek, Michael / Huang, He Helen

    Journal of neuroengineering and rehabilitation

    2019  Volume 16, Issue 1, Page(s) 112

    Abstract: Background: Establishing gait symmetry is a major aim of amputee rehabilitation and may be more attainable with powered prostheses. Though, based on previous work, we postulate that users transfer a previously-learned motor pattern across devices, ... ...

    Abstract Background: Establishing gait symmetry is a major aim of amputee rehabilitation and may be more attainable with powered prostheses. Though, based on previous work, we postulate that users transfer a previously-learned motor pattern across devices, limiting the functionality of more advanced prostheses. The objective of this study was to preliminarily investigate the effect of increased stance time via visual feedback on amputees' gait symmetry using powered and passive knee prostheses.
    Methods: Five individuals with transfemoral amputation or knee disarticulation walked at their self-selected speed on a treadmill. Visual feedback was used to promote an increase in the amputated-limb stance time. Individuals were fit with a commercially-available powered prosthesis by a certified prosthetist and practiced walking during a prior visit. The same protocol was completed with a passive knee and powered knee prosthesis on separate days. We used repeated-measures, two-way ANOVA (alpha = 0.05) to test for significant effects of the feedback and device factors. Our main outcome measures were stance time asymmetry, peak anterior-posterior ground reaction forces, and peak anterior propulsion asymmetry.
    Results: Increasing the amputated-limb stance time via visual feedback significantly improved the stance time symmetry (p = 0.012) and peak propulsion symmetry (p = 0.036) of individuals walking with both prostheses. With the powered knee prosthesis, the highest feedback target elicited 36% improvement in stance time symmetry, 22% increase in prosthesis-side peak propulsion, and 47% improvement in peak propulsion symmetry compared to a no feedback condition. The changes with feedback were not different with the passive prosthesis, and the main effects of device/ prosthesis type were not statistically different. However, subject by device interactions were significant, indicating individuals did not respond consistently with each device (e.g. prosthesis-side propulsion remained comparable to or was greater with the powered versus passive prosthesis for different subjects). Overall, prosthesis-side peak propulsion averaged across conditions was 31% greater with the powered prosthesis and peak propulsion asymmetry improved by 48% with the powered prosthesis.
    Conclusions: Increasing prosthesis-side stance time via visual feedback favorably improved individuals' temporal and propulsive symmetry. The powered prosthesis commonly enabled greater propulsion, but individuals adapted to each device with varying behavior, requiring further investigation.
    MeSH term(s) Adult ; Amputation, Surgical/rehabilitation ; Amputees/rehabilitation ; Biomechanical Phenomena ; Feedback, Sensory ; Female ; Gait ; Humans ; Knee Prosthesis ; Male ; Middle Aged ; Walking ; Young Adult
    Language English
    Publishing date 2019-09-11
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2164377-5
    ISSN 1743-0003 ; 1743-0003
    ISSN (online) 1743-0003
    ISSN 1743-0003
    DOI 10.1186/s12984-019-0583-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Evaluation of the geometric accuracy of computed tomography and microcomputed tomography of the articular surface of the distal portion of the radius of cats.

    Webster, Caroline E / Marcellin-Little, Denis J / Koballa, Erin M / Stallrich, Jonathan W / Harrysson, Ola L A

    American journal of veterinary research

    2019  Volume 80, Issue 10, Page(s) 976–984

    Abstract: Objective: To evaluate accuracy of articular surfaces determined by use of 2 perpendicular CT orientations, micro-CT, and laser scanning.: Sample: 23 cat cadavers.: Procedures: Images of antebrachia were obtained by use of CT (voxel size, 0.6 mm) ... ...

    Abstract Objective: To evaluate accuracy of articular surfaces determined by use of 2 perpendicular CT orientations, micro-CT, and laser scanning.
    Sample: 23 cat cadavers.
    Procedures: Images of antebrachia were obtained by use of CT (voxel size, 0.6 mm) in longitudinal orientation (CT
    Results: Measurement of CT
    Conclusions and clinical relevance: Articular surface models derived from CT images had dimensional errors that approximately matched the voxel size. Thus, CT cannot be used to plan conforming arthroplasties in small joints and could lack precision when used to plan the correction of a limb deformity or repair of a fracture.
    MeSH term(s) Animals ; Cats/anatomy & histology ; Humans ; Radius/diagnostic imaging ; Reproducibility of Results ; X-Ray Microtomography/veterinary
    Language English
    Publishing date 2019-09-26
    Publishing country United States
    Document type Evaluation Study ; Journal Article
    ZDB-ID 390796-x
    ISSN 1943-5681 ; 0002-9645
    ISSN (online) 1943-5681
    ISSN 0002-9645
    DOI 10.2460/ajvr.80.10.976
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Evaluation of the geometric accuracy of computed tomography and microcomputed tomography of the articular surface of the distal portion of the radius of cats

    Webster, Caroline E / Marcellin-Little, Denis J / Koballa, Erin M / Stallrich, Jonathan W / Harrysson, Ola L. A

    American journal of veterinary research. 2019 Oct., v. 80, no. 10

    2019  

    Abstract: OBJECTIVE To evaluate accuracy of articular surfaces determined by use of 2 perpendicular CT orientations, micro-CT, and laser scanning. SAMPLE 23 cat cadavers. PROCEDURES Images of antebrachia were obtained by use of CT (voxel size, 0.6 mm) in ... ...

    Abstract OBJECTIVE To evaluate accuracy of articular surfaces determined by use of 2 perpendicular CT orientations, micro-CT, and laser scanning. SAMPLE 23 cat cadavers. PROCEDURES Images of antebrachia were obtained by use of CT (voxel size, 0.6 mm) in longitudinal orientation (CTLO images) and transverse orientation (CTTO images) and by use of micro-CT (voxel size, 0.024 mm) in a longitudinal orientation. Images were reconstructed. Craniocaudal and mediolateral length, radius of curvature, and deviation of the articular surface of the distal portion of the radius of 3-D renderings for CTLO, CTTO, and micro-CT images were compared with results of 3-D renderings acquired with a laser scanner (resolution, 0.025 mm). RESULTS Measurement of CTLO and CTTO images overestimated craniocaudal and mediolateral length of the articular surface by 4% to 10%. Measurement of micro-CT images underestimated craniocaudal and mediolateral length by 1%. Measurement of CTLO and CTTO images underestimated mediolateral radius of curvature by 15% and overestimated craniocaudal radius of curvature by > 100%; use of micro-CT images underestimated them by 3% and 5%, respectively. Mean ± SD surface deviation was 0.26 ± 0.09 mm for CTLO images, 0.30 ± 0.28 mm for CTTO images, and 0.04 ± 0.02 mm for micro-CT images. CONCLUSIONS AND CLINICAL RELEVANCE Articular surface models derived from CT images had dimensional errors that approximately matched the voxel size. Thus, CT cannot be used to plan conforming arthroplasties in small joints and could lack precision when used to plan the correction of a limb deformity or repair of a fracture.
    Keywords cadaver ; cats ; geometry ; micro-computed tomography ; models ; radius (bone) ; scanners ; veterinary medicine
    Language English
    Dates of publication 2019-10
    Size p. 976-984.
    Publishing place American Veterinary Medical Association
    Document type Article
    ZDB-ID 390796-x
    ISSN 1943-5681 ; 0002-9645
    ISSN (online) 1943-5681
    ISSN 0002-9645
    DOI 10.2460/ajvr.80.10.976
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Biological resurfacing in a canine model of hip osteoarthritis.

    Estes, Bradley T / Enomoto, Masataka / Moutos, Franklin T / Carson, Megan A / Toth, Jeffrey M / Eggert, Peter / Stallrich, Jonathan / Willard, Vincent P / Veis, Deborah J / Little, Dianne / Guilak, Farshid / Lascelles, B Duncan X

    Science advances

    2021  Volume 7, Issue 38, Page(s) eabi5918

    Abstract: Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissue-engineered, bicomponent ... ...

    Abstract Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissue-engineered, bicomponent implant to restore hip function in a canine hip osteoarthritis model. This resorbable implant was specifically designed to function mechanically from the time of repair and to biologically integrate with native tissues for long-term restoration. A massive osteochondral lesion was created in the hip of skeletally mature hounds and repaired with the implant or left empty (control). Longitudinal outcome measures over 6 months demonstrated that the implant dogs returned to normal preoperative values of pain and function. Anatomical structure and functional biomechanical properties were also restored in the implanted dogs. Control animals never returned to normal and exhibited structurally deficient repair. This study provides clinically relevant evidence that the bicomponent implant may be a potential therapy for moderate hip osteoarthritis.
    Language English
    Publishing date 2021-09-15
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2810933-8
    ISSN 2375-2548 ; 2375-2548
    ISSN (online) 2375-2548
    ISSN 2375-2548
    DOI 10.1126/sciadv.abi5918
    Database MEDical Literature Analysis and Retrieval System OnLINE

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