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White matter (WM) degeneration is a critical component of early Alzheimer's disease (AD) pathophysiology. Diffusion-weighted imaging (DWI) models, including diffusion tensor imaging (DTI), neurite orientation dispersion and density imaging (NODDI), and mean apparent propagator MRI (MAP-MRI), have the potential to identify early neurodegenerative WM changes associated with AD.We imaged 213 (198 cognitively unimpaired) aging adults with DWI and used tract-based spatial statistics to compare 15 DWI metrics of WM microstructure to 9 cerebrospinal fluid (CSF) markers of AD pathology and neurodegeneration treated as continuous variables.We found widespread WM injury in AD, as indexed by robust associations between DWI metrics and CSF biomarkers. MAP-MRI had more spatially diffuse relationships with AβOur results suggest that WM degeneration may be more pervasive in AD than is commonly appreciated and that innovative DWI models such as MAP-MRI may provide clinically viable biomarkers of AD-related neurodegeneration in the earliest stages of AD progression.

Knowledge of ion–atom ionization cross-sections is of great importance for many accelerator applications. We have recently investigated theoretically and experimentally the stripping of more than 18 different pairs of projectile and target particles in the range of 3–38 MeV/amu to study the range of validity of both the Born approximation and the classical trajectory calculation. In most cases, both approximations give similar results. However, for fast projectile velocities and low-ionization potentials, the classical approach is not valid and can overestimate the stripping cross-sections by neutral atoms by an order-of-magnitude. Therefore, a hybrid approach that automatically chooses between the Born approximation and the classical mechanics approximation depending on the parameters of the collision has been developed. When experimental data and theoretical calculations are not available, approximate formulas are frequently used. Based on experimental data and theoretical predictions, a new fit formula for ionization cross-sections by fully stripped ions is proposed. The resulting plots of the scaled ionization cross-sections of hydrogen by fully stripped ions are presented. The new fit formula has also been applied to the ionization cross-sections of helium. Again, the experimental and theoretical results merge close together on the scaled plot.