Prevalence, distribution, and severity of cerebral amyloid angiopathy differ between Lewy body diseases and Alzheimer's disease.

Dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD), and Parkinson's disease (PD) collectively known as Lewy body diseases (LBDs) are neuropathologically characterised by α-synuclein deposits (Lewy bodies and Lewy neurites). However, LBDs also exhibit pathology associated with Alzheimer's disease (AD) (i.e.

Demonstration of a quasi-monostatic autonomous underwater vehicle based high duty cycle active sonar.

The feasibility of resolving target returns within receive signals collected by a continuously transmitting quasi-monostatic, broadband, autonomous underwater vehicle (AUV) based sonar is explored. Theoretical studies supported by experimental results suggest that it is possible to capture the source-to-receiver coupling response and target scattering with sufficient fidelity during the continuous transmission to enable detection and (potentially) classification processing. Demonstrations focused upon the detection of a bottomed target object at sea using transmit signals with duty cycles of 60% and 100% indicate that such an approach is feasible for a representative AUV-based side looking sonar system operating in shallow water.

Acoustic identification of buried underwater unexploded ordnance using a numerically trained classifier (L).

Using a finite element-based structural acoustics code, simulations were carried out for the acoustic scattering from an unexploded ordnance rocket buried in the sediment under 3 m of water. The simulation treated 90 rocket burial angles in steps of 2°. The simulations were used to train a generative relevance vector machine (RVM) algorithm for identifying rockets buried at unknown angles in an actual water/sediment environment.

Elastic Pekeris waveguide normal mode solution comparisons against laboratory data.

Following the derivation presented by Press and Ewing [Geophysics 15, 426-446 (1950)], a normal mode solution for the Pekeris waveguide problem with an elastic bottom is outlined. The analytic solution is benchmarked against data collected in an experiment performed at the Naval Research Laboratory [Collis et al., J.

Seismo-acoustic ray model benchmarking against experimental tank data.

Acoustic predictions of the recently developed traceo ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions.

Isolating scattering resonances of an air-filled spherical shell using iterative, single-channel time reversal.

Iterative, single-channel time reversal is employed to isolate backscattering resonances of an air-filled spherical shell in a frequency range of 0.5-20 kHz. Numerical simulations of free-field target scattering suggest improved isolation of the dominant target response frequency in the presence of varying levels of stochastic noise, compared to processing returns from a single transmission and also coherent averaging.

Experimental testing of the variable rotated elastic parabolic equation.

A series of laboratory experiments was conducted to obtain high-quality data for acoustic propagation in shallow water waveguides with sloping elastic bottoms. Accurate modeling of transmission loss in these waveguides can be performed with the variable rotated parabolic equation method. Results from an earlier experiment with a flat or sloped slab of polyvinyl chloride (PVC) demonstrated the necessity of accounting for elasticity in the bottom and the ability of the model to produce benchmark-quality agreement with experimental data [J.

Experimental testing of the noise-canceling processor.

Signal-processing techniques for localizing an acoustic source buried in noise are tested in a tank experiment. Noise is generated using a discrete source, a bubble generator, and a sprinkler. The experiment has essential elements of a realistic scenario in matched-field processing, including complex source and noise time series in a waveguide with water, sediment, and multipath propagation.

Small-slope simulation of acoustic backscatter from a physical model of an elastic ocean bottom.

An underwater acoustic experiment with a two-dimensional rough interface, milled from a slab of PVC, was performed at a tank facility. The purpose was to verify the predictions of numerical models of acoustic rough surface scattering, using a manufactured physical model of an ocean bottom that featured shear effects, nonhomogeneous roughness statistics, and root-mean-square roughness amplitude on the order of the acoustic wavelength. Predictions of the received time series and interface scattering strength in the 100-300 kHz band were obtained from the Bottom Reverberation from Inhomogeneities and Surfaces-Small-Slope Approximation (BORIS-SSA) numerical scattering model.

Comparison of simulations and data from a seismo-acoustic tank experiment.

A tank experiment was carried out to investigate underwater sound propagation over an elastic bottom in flat and sloping configurations. The purpose of the experiment was to evaluate range-dependent propagation models with high-quality experimental data. The sea floor was modeled as an elastic medium by a polyvinyl chloride slab.

At-sea measurements of sound penetration into sediments using a buried vertical synthetic array.

Acoustic bottom penetration experiments were carried out in a medium-grain sandy bottom at a site in St. Andrews Bay, Florida. These investigations used a new buried, vertical, one-dimensional synthetic array system where a small hydrophone was water-jetted into the sediment to a depth of approximately 2 m.