The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform

Lorenzo Rosasco - One of the best experts on this subject based on the ideXlab platform.

  • hyperbolic manifold regression
    International Conference on Artificial Intelligence and Statistics, 2020
    Co-Authors: Gian Maria Marconi, Carlo Ciliberto, Lorenzo Rosasco
    Abstract:

    Geometric representation learning has recently shown great promise in several machine learning settings, ranging from relational learning to language processing and generative models. In this work, we consider the problem of performing manifold-valued regression onto an hyperbolic space as an Intermediate Component for a number of relevant machine learning applications. In particular, by formulating the problem of predicting nodes of a tree as a manifold regression task in the hyperbolic space, we propose a novel perspective on two challenging tasks: 1) hierarchical classification via label embeddings and 2) taxonomy extension of hyperbolic representations. To address the regression problem we consider previous methods as well as proposing two novel approaches that are computationally more advantageous: a parametric deep learning model that is informed by the geodesics of the target space and a non-parametric kernel-method for which we also prove excess risk bounds. Our experiments show that the strategy of leveraging the hyperbolic geometry is promising. In particular, in the taxonomy expansion setting, we find that the hyperbolic-based estimators significantly outperform methods performing regression in the ambient Euclidean space.

Daniel J Berry - One of the best experts on this subject based on the ideXlab platform.

  • technical note validation of a motion analysis system for measuring the relative motion of the Intermediate Component of a tripolar total hip arthroplasty prosthesis
    Medical Engineering & Physics, 2005
    Co-Authors: Qingshan Chen, Jean Yves Lazennec, Olivier Guyen, Amy Kinbrum, Daniel J Berry, Kai Nan An
    Abstract:

    Abstract Tripolar total hip arthroplasty (THA) prosthesis had been suggested as a method to reduce the occurrence of hip dislocation and microseparation. Precisely measuring the motion of the Intermediate Component in vitro would provide fundamental knowledge for understanding its mechanism. The present study validates the accuracy and repeatability of a three-dimensional motion analysis system to quantitatively measure the relative motion of the Intermediate Component of tripolar total hip arthroplasty prostheses. Static and dynamic validations of the system were made by comparing the measurement to that of a potentiometer. Differences between the mean system-calculated angle and the angle measured by the potentiometer were within ±1°. The mean within-trial variability was less than 1°. The mean slope was 0.9–1.02 for different angular velocities. The dynamic noise was within 1°. The system was then applied to measure the relative motion of an eccentric THA prosthesis. The study shows that this motion analysis system provides an accurate and practical method for measuring the relative motion of the tripolar THA prosthesis in vitro, a necessary first step towards the understanding of its in vivo kinematics.

  • technical note validation of a motion analysis system for measuring the relative motion of the Intermediate Component of a tripolar total hip arthroplasty prosthesis
    Medical Engineering & Physics, 2005
    Co-Authors: Qingshan Chen, Jean Yves Lazennec, Olivier Guyen, Amy Kinbrum, Daniel J Berry
    Abstract:

    Tripolar total hip arthroplasty (THA) prosthesis had been suggested as a method to reduce the occurrence of hip dislocation and microseparation. Precisely measuring the motion of the Intermediate Component in vitro would provide fundamental knowledge for understanding its mechanism. The present study validates the accuracy and repeatability of a three-dimensional motion analysis system to quantitatively measure the relative motion of the Intermediate Component of tripolar total hip arthroplasty prostheses. Static and dynamic validations of the system were made by comparing the measurement to that of a potentiometer. Differences between the mean system-calculated angle and the angle measured by the potentiometer were within +/-1 degrees . The mean within-trial variability was less than 1 degrees . The mean slope was 0.9-1.02 for different angular velocities. The dynamic noise was within 1 degrees . The system was then applied to measure the relative motion of an eccentric THA prosthesis. The study shows that this motion analysis system provides an accurate and practical method for measuring the relative motion of the tripolar THA prosthesis in vitro, a necessary first step towards the understanding of its in vivo kinematics.

Qingshan Chen - One of the best experts on this subject based on the ideXlab platform.

  • technical note validation of a motion analysis system for measuring the relative motion of the Intermediate Component of a tripolar total hip arthroplasty prosthesis
    Medical Engineering & Physics, 2005
    Co-Authors: Qingshan Chen, Jean Yves Lazennec, Olivier Guyen, Amy Kinbrum, Daniel J Berry, Kai Nan An
    Abstract:

    Abstract Tripolar total hip arthroplasty (THA) prosthesis had been suggested as a method to reduce the occurrence of hip dislocation and microseparation. Precisely measuring the motion of the Intermediate Component in vitro would provide fundamental knowledge for understanding its mechanism. The present study validates the accuracy and repeatability of a three-dimensional motion analysis system to quantitatively measure the relative motion of the Intermediate Component of tripolar total hip arthroplasty prostheses. Static and dynamic validations of the system were made by comparing the measurement to that of a potentiometer. Differences between the mean system-calculated angle and the angle measured by the potentiometer were within ±1°. The mean within-trial variability was less than 1°. The mean slope was 0.9–1.02 for different angular velocities. The dynamic noise was within 1°. The system was then applied to measure the relative motion of an eccentric THA prosthesis. The study shows that this motion analysis system provides an accurate and practical method for measuring the relative motion of the tripolar THA prosthesis in vitro, a necessary first step towards the understanding of its in vivo kinematics.

  • technical note validation of a motion analysis system for measuring the relative motion of the Intermediate Component of a tripolar total hip arthroplasty prosthesis
    Medical Engineering & Physics, 2005
    Co-Authors: Qingshan Chen, Jean Yves Lazennec, Olivier Guyen, Amy Kinbrum, Daniel J Berry
    Abstract:

    Tripolar total hip arthroplasty (THA) prosthesis had been suggested as a method to reduce the occurrence of hip dislocation and microseparation. Precisely measuring the motion of the Intermediate Component in vitro would provide fundamental knowledge for understanding its mechanism. The present study validates the accuracy and repeatability of a three-dimensional motion analysis system to quantitatively measure the relative motion of the Intermediate Component of tripolar total hip arthroplasty prostheses. Static and dynamic validations of the system were made by comparing the measurement to that of a potentiometer. Differences between the mean system-calculated angle and the angle measured by the potentiometer were within +/-1 degrees . The mean within-trial variability was less than 1 degrees . The mean slope was 0.9-1.02 for different angular velocities. The dynamic noise was within 1 degrees . The system was then applied to measure the relative motion of an eccentric THA prosthesis. The study shows that this motion analysis system provides an accurate and practical method for measuring the relative motion of the tripolar THA prosthesis in vitro, a necessary first step towards the understanding of its in vivo kinematics.

Gian Maria Marconi - One of the best experts on this subject based on the ideXlab platform.

  • hyperbolic manifold regression
    International Conference on Artificial Intelligence and Statistics, 2020
    Co-Authors: Gian Maria Marconi, Carlo Ciliberto, Lorenzo Rosasco
    Abstract:

    Geometric representation learning has recently shown great promise in several machine learning settings, ranging from relational learning to language processing and generative models. In this work, we consider the problem of performing manifold-valued regression onto an hyperbolic space as an Intermediate Component for a number of relevant machine learning applications. In particular, by formulating the problem of predicting nodes of a tree as a manifold regression task in the hyperbolic space, we propose a novel perspective on two challenging tasks: 1) hierarchical classification via label embeddings and 2) taxonomy extension of hyperbolic representations. To address the regression problem we consider previous methods as well as proposing two novel approaches that are computationally more advantageous: a parametric deep learning model that is informed by the geodesics of the target space and a non-parametric kernel-method for which we also prove excess risk bounds. Our experiments show that the strategy of leveraging the hyperbolic geometry is promising. In particular, in the taxonomy expansion setting, we find that the hyperbolic-based estimators significantly outperform methods performing regression in the ambient Euclidean space.

Kai Nan An - One of the best experts on this subject based on the ideXlab platform.

  • technical note validation of a motion analysis system for measuring the relative motion of the Intermediate Component of a tripolar total hip arthroplasty prosthesis
    Medical Engineering & Physics, 2005
    Co-Authors: Qingshan Chen, Jean Yves Lazennec, Olivier Guyen, Amy Kinbrum, Daniel J Berry, Kai Nan An
    Abstract:

    Abstract Tripolar total hip arthroplasty (THA) prosthesis had been suggested as a method to reduce the occurrence of hip dislocation and microseparation. Precisely measuring the motion of the Intermediate Component in vitro would provide fundamental knowledge for understanding its mechanism. The present study validates the accuracy and repeatability of a three-dimensional motion analysis system to quantitatively measure the relative motion of the Intermediate Component of tripolar total hip arthroplasty prostheses. Static and dynamic validations of the system were made by comparing the measurement to that of a potentiometer. Differences between the mean system-calculated angle and the angle measured by the potentiometer were within ±1°. The mean within-trial variability was less than 1°. The mean slope was 0.9–1.02 for different angular velocities. The dynamic noise was within 1°. The system was then applied to measure the relative motion of an eccentric THA prosthesis. The study shows that this motion analysis system provides an accurate and practical method for measuring the relative motion of the tripolar THA prosthesis in vitro, a necessary first step towards the understanding of its in vivo kinematics.