A direct numerical simulation is made for the incompressible turbulent flow in the 180 deg curved channel with a long straight portion connected to its exit port. An examination is made for how the organized coherent vortex grows and decays in the curved channel: the radius ratio of 0.92, the aspect ratio of 7.2, and the succeeding straight section length of 75 times the channel half width. The 1552 × 91 × 128 ( = 18,427,136) grids are allocated to the computational domain. The frictional-velocity-based Reynolds number is kept at 150 to resolve the long domain including curved and straight regions. In contrast to that the coherent vortex grows along the concave wall, the vortex remains strong in the convex-wall side after the curvature accompanying a tail of the small-scale turbulence near the convex wall. The dissimilarity between the onset and disappearing of the coherent vortex essentially comes from the mean pressure gradient, which aids or averts the near-wall fluid oppositely between the curvature inlet and the exit. The mean flow is decelerated near the inlet of the convex wall to destabilize the flow and to trigger the onset of the coherent vortex. Contrary, the mean flow is accelerated near the exit of the convex wall to weaken the coherent vortex, and is decelerated near the exit of the concave wall to enhance the turbulence. Therefore, the turbulence enhancement and attenuation occurs oppositely between the inlet and exit of the curvature, and the coherent vortex draws a wake in the convex-side rather than the concave-side where it starts.

In this report, we describe a case of cervical vertebral arteriovenous fistula (AVF) associated with neurofibromatosis type 1(NF1) presented as radiculopathy. Case Presentation: A 65-year-old female patient diagnosed with left cervical vertebral artery lesion-like aneurysms and NF1 incidentally. After 5 years, she presented with neck pain and left upper weakness. Examinations revealed left vertebral AVF. Endovascular therapy was performed and her symptoms were improved. Conclusion: Endovascular therapy should be performed if asymptomatic cervical vertebral aneurysms associated with NF1 are growing or become symptomatic. Keywords▶ neurofibromatosis type 1, cervical vertebral arteriovenous fistula, radiculopathy This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives International License.

Direct numerical simulation was performed for a spatially advancing turbulent flow in a two-dimensional curved channel. The radius ratio of the curved part, α , was set at 0.92, the same as Kobayashi et al.'s experiment. And the friction Reynolds number, Re τ0 , was set at 550. Numerically solved mean velocity field showed trends consistent with the experiment. As a result, the validity of the simulation was confirmed. Instantaneous flow field implied that micro-scale structures near the outer wall were related to the birth and growth of large-scale vortices.

This study investigated the correlation of the cognitive functions with fall history. [Participants and Methods] The mental and physical conditions of the participants were assessed using the Mini-Mental State Examination, the Tokyo Metropolitan Institute of Gerontology Index of Competence, the Life-Space Assessment-Japanese edition, and the 10-meter Walk Test. Reaction Time and Premotor Time were measured while subjects were performing the Simple Reaction Task, the Go/No-go Reaction Task, and the Probe Reaction Task. [Results] The Premotor Times which correspond to the cognitive process were significantly longer in the fall group. [Conclusion] Delay of the cognitive process increases the risk of falls.