PURPOSE To test patient acceptance and reproducibility of the 3D magnetic resonance elastography (MRE) brain exam using a soft vibration source, and to determine if MRE could noninvasively measure a change in the elastic properties of the brain parenchyma due to Alzheimer's disease (AD). MATERIALS AND METHODS MRE exams were performed using an accelerated spin-echo echo planar imaging (EPI) pu...

Single cardiac myocytes and skeletal myocyte fragments, devoid of interstitial collagen but with intact glycocalyx, were prepared by mechanical disaggregation of hamster ventricular myocardium and caudal gracilis muscle, respectively. Passive stiffness was studied by examining the sarcomere length-tension relationship over the approximate Eulerian stress range of 0-20 mN/mm2 for cardiac myocyte...

The stiffness of the aorta can be determined by measuring carotid-femoral pulse wave velocity (PWV(cf)). PWV may also influence the contour of the peripheral pulse, suggesting that contour analysis might be used to assess large artery stiffness. An index of large artery stiffness (SI(DVP)) derived from the digital volume pulse (DVP) measured by transmission of IR light (photoplethysmography) wa...

The paper studies stochastic dynamics of a two-degree-of-freedom system, where primary linear system is connected to nonlinear energy sink with cubic stiffness nonlinearity and viscous damping. While the mass subjected zero-mean Gaussian white noise excitation, main objective this study maximise efficiency targeted transfer in system. A surrogate optimisation algorithm proposed for purpose adop...

A time-varying autoregressive model with time-varying coefficients is introduced in this paper for parameter extraction from non-stationary vibration signals. With this model, the relationship between linear time-varying modal parameters, i.e., instantaneous frequencies and damping factors, and time-varying autoregressive model coefficients is established. The time-varying autoregressive modeli...

Friction characteristics with respect to surface topographic orientation were investigated using surfaces of different materials and fabricated with grooves of different scales. Scratching friction tests were conducted using a nano-indentation-scratching system with the tip motion parallel or perpendicular to the groove orientation. Similar friction anisotropy trends were observed for all the s...

We present a Ritz-Galerkin discretization on sparse grids using pre-wavelets, which allows to solve elliptic differential equations with variable coefficients for dimension d = 2, 3 and higher dimensions d > 3. The method applies multilinear finite elements. We introduce an efficient algorithm for matrix vector multiplication using a Ritz-Galerkin discretization and semi-orthogonality. This alg...

We consider parabolic partial differential equations where the support of the sources or of the inhomogenous Neumann boundary conditions undergoes an oscillatory motion. The timescale of this oscillation is much smaller than the characteristic time scale of diffusion, which is of main interest. Resolution of the smallest timescale constitutes a strong restriction on the stepsize of time integra...

While the main contributor for drop jump (DJ) performance is calf muscle–tendon unit (MTU), countermovement (CMJ) performance, it quadriceps MTU. However, to date, not clear if muscle and/or tendon stiffness of respective MTUs can be related DJ or CMJ performance. Therefore, purpose this study was investigate relationships between and parameters tissue (i.e., stiffness, stiffness) MTU MTU, resp...