We demonstrate that the conventional application of linear models to the analysis of optoelectromechanical properties of nanostructures in bandstructure engineering could be inadequate. Such linear models are usually derived from the traditional bottom-up approach applied to the analysis of nanostructure properties. At the same time, in the hierarchy of mathematical models for semiconductor device modelling constructed on the basis of the top-down approach, we deal predominantly with models where nonlinearity is essential. In this contribution, we analyze these two fundamental approaches in bridging the scales in mathematical models for the description of optoelectromechanical properties of nanostructures. The focus of the present paper is on a model based on the coupled Schrodinger-Poisson system where we account consistently for the piezoelectric effect and analyze the influence of different nonlinear terms in strain components. The examples given in this paper show that the piezoelectric effect contributions are essential and have to be accounted for with fully coupled models. While in structural applications of piezoelectric materials at larger scales, the minimization of the full electromechanical energy is now a routine in many engineering applications, in bandstructure engineering conventional approaches are still based on linear models with minimization of uncoupled, purely elastic energy functionals with respect to displacements. Generalizations of the existing models for bandstructure calculations are presented in this paper in the context of coupled effects.

Mesenteric paragangliomas are a rare entity; consequently, only 12 cases have been reported to date. Although considered benign and often found incidentally, they have the potential to metastasize and are an important diagnosis to consider for patients with a mesenteric tumor. We report the case of a 71-year-old woman who was found on magnetic resonance imaging to have an incidental, large, complex, intra-abdominal mass that had initially been misdiagnosed as ovarian in origin. She underwent an open resection of the tumor and adjacent small bowel with no perioperative complications; histology confirmed the mass to be a mesenteric paraganglioma. This case report highlights several important key issues regarding paraganglioma, including diagnosis, imaging, genetic testing, and surgical resection. The results of a literature review are also discussed.

A unified variational framework and finite element simulations of phase transformation dynamics in a shape memory alloy thin film are reported in this paper. The computational model is based on an approach, which combines the lattice based kinetics involving the order variables and nonequilibrium thermodynamics. Algorithmic and computational issues are discussed. Numerical results on phase nucleation under mechanical loading are reported.

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