PNAS Plus Significance Statements
Accounting for inhomogeneous broadening in nano-optics by electromagnetic modeling based on Monte Carlo methods
Herman Gudjonson, Mikhail A. Kats, Kun Liu, Zhihong Nie, Eugenia Kumacheva, and Federico Capasso
The advent of nanotechnology has enabled the study of physical phenomena in structures with nanoscale dimensions. Pushing the limits of fabrication techniques inevitably leads to uncertainties—for example, an array of nanoscale resonators may be designed to be identical, but in fact has a distribution of sizes due to fabrication imperfections, leading to a distribution of responses. In optical experiments involving collections of nanostructures these effects are often acknowledged but rarely quantified. We demonstrate (pp. E639–E644) a technique that combines electromagnetic simulations with a Monte Carlo sampling technique to rigorously account for “inhomogeneous broadening” of optical resonances as a result of fabrication or synthesis imperfections. This approach has wide applicability to any experiments involving collections of structures designed to be identical.
Identifying and mapping cell-type-specific chromatin programming of gene expression
Troels T. Marstrand and John D. Storey
In order for genes to be expressed in humans, the DNA corresponding to a gene and its regulatory elements must be accessible. It is hypothesized that this accessibility and its effect on gene expression plays a major role in defining the different cell types that make up a human. We have only recently been able to make the measurements necessary to model DNA accessibility and gene-expression variation in multiple human cell types at the genome-wide level (pp. E645–E654). We develop and apply a new quantitative framework for identifying locations in the human genome whose DNA …
