The prevailing view on multiple sclerosis etiopathogenesis has been challenged by the suggested new entity chronic cerebrospinal venous insufficiency. To test this hypothesis, we studied 21 relapsing-remitting multiple sclerosis cases and 20 healthy controls with phasecontrast magnetic resonance imaging. In addition, in multiple sclerosis cases we performed contrastenhanced magnetic resonance a...

By use of a stochastic generalization of the Hodgkin-Huxley model we investigate the phenomenon of Stochastic Resonance (SR) for a distribution of ion channels within a cluster of variable size. In the presence of a periodic stimulus we demonstrate intrinsic SR vs. decreasing patch size, or, put differently, vs. increasing internal noise strength. SR with external noise occurs only for large cl...

Miniature coils for magnetic resonance imaging and spectroscopy are demonstrated. A rectangular Helmholtz arrangement based on a pair of substrates separated by spherical alignment spacers is investigated. An optimal geometry is developed using simple theory and verified by numerical analysis. Prototypes are fabricated using silicon substrates shaped by anisotropic etching to form a trough to h...

We show, by molecular dynamics simulations, that 2 : 1 internal resonance may occur between a radial breathing mode (RBM) and a circumferential flexural mode (CFM) in single-walled carbon nanotubes (SWCNTs). When the RBM vibration amplitude is greater than a critical value, automatic transformations between the RBM and CFM with approximately half RBM-frequency are observed. This discovery in th...

Vascular anomalies of major venous vessels are rarely seen. Moreover, congenital absence of internal jugular vein is extremely uncommon. In our case, a female patient presented with primary unknown left cervical mass. Cervical ultrasonography demonstrated absence of right internal jugular vein. In addition, computed tomography and dynamic magnetic resonance imaging scans confirmed this diagnosi...

Abstract Adding noise to a sensory signal generally decreases human performance. However noise can improve performance too, due to a process called stochastic resonance (SR). This paradoxical effect may be exploited in psychophysical experiments, to provide additional insights into how the sensory system deals with noise. Here, I develop a model for stochastic resonance to study the influence o...