Although N3 is perhaps the most widely used method for MRI bias field correction, its underlying mechanism is in fact not well understood. Specifically, the method relies on a relatively heuristic recipe of alternating iterative steps that does not optimize any particular objective function. In this paper we explain the successful bias field correction properties of N3 by showing that it implic...

Brain image segmentation is an important part of medical image analysis. Due to the effect of imaging mechanism, MR images usually intensity in homogeneity, which is also named as bias field. Traditional Gaussian Mixed Model (GMM) method is hard to obtain satisfied segmentation results with the effect of noise and bias field. We propose a novel model based on GMM and nonlocal information. The i...

Targeted gene correction employs a site-specific DNA lesion to promote homologous recombination that eliminates mutation in a disease gene of interest. The double-strand break typically used to initiate correction can also result in genomic instability if deleterious repair occurs rather than gene correction, possibly compromising the safety of targeted gene correction. Here we show that single...

Contributions to the fifth-order nonlinear optical susceptibility 5 of a collection of homogeneously broadened two-level atoms that scale as N2 at 3 2 and N2 at 3 2, where at 3 is the lower-order atomic hyperpolarizability and N is the atomic number density, are predicted theoretically. These “cascaded” contributions are a consequence of local-field effects. We determine them from a fifth-order...