Loading history and age are factors for disc degeneration and disc biomechanics; however, their relationship is unclear. To evaluate disc biomechanics, we conducted an experimental, anatomical and numerical approach t...Loading history and age are factors for disc degeneration and disc biomechanics; however, their relationship is unclear. To evaluate disc biomechanics, we conducted an experimental, anatomical and numerical approach to distinguish discs with mild and severe degeneration. In the experimental procedure, 10 cadaveric lumbar discs are tested to static and dynamic compression, and the elastic and viscous moduli and the dynamic parameters are reported. The morphology of disc degeneration is gained with MRI (magnetic resonance imaging) and used to generate a nonlinear finite element model of a degenerated disc, and assisted with the experimental results in order to numerically investigate the distribution of stresses and strains within the disc. The results show a promising methodology for the study of intervertebral disc biomechanics and in general other tissues, organs and medical devices.展开更多
Let m, n 〉 1 be two coprime integers. In this paper, we prove that a finite solvable group is nilpotent if the set of the conjugacy class sizes of its primary and biprimary elements is {1, rn, n, mn}.
文摘Loading history and age are factors for disc degeneration and disc biomechanics; however, their relationship is unclear. To evaluate disc biomechanics, we conducted an experimental, anatomical and numerical approach to distinguish discs with mild and severe degeneration. In the experimental procedure, 10 cadaveric lumbar discs are tested to static and dynamic compression, and the elastic and viscous moduli and the dynamic parameters are reported. The morphology of disc degeneration is gained with MRI (magnetic resonance imaging) and used to generate a nonlinear finite element model of a degenerated disc, and assisted with the experimental results in order to numerically investigate the distribution of stresses and strains within the disc. The results show a promising methodology for the study of intervertebral disc biomechanics and in general other tissues, organs and medical devices.
基金supported by National Natural Science Foundation of China(Grant Nos.11201401 and 11101258)National Science Foundation for Postdoctoral Scientists of China(Grant No.20100480582)University of Jinan Research Funds for Doctors(Grant Nos.XBS1335 and XBS1336)
文摘Let m, n 〉 1 be two coprime integers. In this paper, we prove that a finite solvable group is nilpotent if the set of the conjugacy class sizes of its primary and biprimary elements is {1, rn, n, mn}.