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This paper describes experiments exploring the three-dimensional (3D) Rayleigh–Taylor instability at a blast-wave-driven interface. This experiment is well scaled to the He/H interface during the explosion phase of SN1987A. In the experiments, ∼5 kJ of energy from the Omega laser was used to create a planar blast wave in a plastic disk, which is accelerated into a lower-density foam. These circumstances induce the Richtmyer–Meshkov instability and, after the shock passes the interface, the system quickly becomes dominated by the Rayleigh–Taylor instability. The plastic disk has an intentional pattern machined at the plastic/foam interface. This perturbation is 3D with a basic structure of two orthogonal sine waves with a wavelength of 71 μm and an amplitude of 2.5 μm. Additional long-wavelength modes with a wavelength of either 212 or 424 μm are added onto the single-mode pattern. The addition of the long-wavelength modes was motivated by the results of previous experiments where material penetrated unexpectedly to the shock front, perhaps due to an unintended structure. The current experiments and simulations were performed to explore the effects of this unintended structure; however, we were unable to reproduce the previous results. [ABSTRACT FROM AUTHOR]

Background: Despite the growing recognition of the importance of cognitive symptoms for the diagnosis and management of atypical parkinsonion syndromes, the cognitive assessment of the patients in clinical practice often remains very limited. Objectives: To examine the ability of a brief and simple cognitive screening test to detect cognitive deficits in atypical parkinsonian syndromes. Methods: Addenbrooke's cognitive examination (ACE), the mini-mental state examination (MMSE), and the dementia rating scale (DRS) were applied to 26 patients with multiple system atrophy (MSA), 39 with progressive supranuclear palsy (PSP), and 25 with corticobasal degeneration (CBD). The results were then compared with those obtained in 30 healthy age matched volunteers and 30 patients with Alzheimer's disease. Results: In all four diseases the rate of detection of cognitive impairment on ACE was, higher than on MMSE and comparable with DRS. The severity of cognitive impairment was most pronounced in the CBD group, which showed a similar degree of impairment to the Alzheimer group. In contrast, MSA patients were the least cognitively impaired. The PSP group took on intermediate positions. Conclusions: Cognitive impairment in atypical parkinsonian syndromes can be detected using, a brief and clinically applicable bedside test luck as ACE. [ABSTRACT FROM AUTHOR]