Leonardo S. Barbosa | Searcharxiv

arXiv2021

First-principle investigation of boron nitride nanobelt

In this paper, we report a new boron nitride molecular structure called BN-nanobelt, an inorganic analog of (12) cyclophenacene synthesized in 2017. An extensive investigation using Density Functional Theory (DFT) and Quantum Molecular Dynamics (QMD) calculations showed that BN-nanobelt is a structurally and thermally stable molecule with all positive vibrational frequencies. BN-nanobelt behaves as an insulator, and it absorbs in the ultraviolet region, suggesting a potential application as a UV detector. All results presented in this paper indicate structural stability and the possibility of its synthesis. We hope that the proposed BN-nanobelt structure could stimulate further experimental investigations on its synthesis and bring potential novel technological applications.

cond-mat.mtrl-sci↗

arXiv2015

Backward Renormalization Priors and the Cortical Source Localization Problem with EEG or MEG

We study source localization from high dimensional M/EEG data by extending a multiscale method based on Entropic inference devised to increase the spatial resolution of inverse problems. This method is used to construct informative prior distributions in a manner inspired in the context of fMRI (Amaral et al 2004). We construct a set of renormalized lattices that approximate the cortex region where the source activity is located and address the related problem of defining the relevant variables in a coarser scale representation of the cortex. The priors can be used in conjunction with other Bayesian methods such as the Variational Bayes method (VB, Sato et al 2004). The central point of the algorithm is that it uses a posterior obtained at a coarse scale to induce a prior at the next finer scale stage of the problem. We present results which suggest, on simulated data, that this way of including prior information is a useful aid for the source location problem. This is judged by the rate and magnitude of errors in source localization. Better convergence times are also achieved. We also present results on public data collected during a face recognition task.

q-bio.QM↗