Continuum limits of discrete isoperimetric problems and Wulff shapes in lattices and quasicrystal tilings.

We prove discrete-to-continuum convergence of interaction energies defined on lattices in the Euclidean space (with interactions beyond nearest neighbours) to a crystalline perimeter, and we discuss the possible Wulff shapes obtainable in this way. Exploiting the "multigrid construction" of quasiperiodic tilings (which is an extension of De Bruijn's "pentagrid" construction of Penrose tilings) we adapt the same techniques to also find the macroscopical homogenized perimeter when we microscopically rescale a given quasiperiodic tiling.

Degenerate Elastic Networks.

We minimize a linear combination of the length and the -norm of the curvature among networks in belonging to a given class determined by the number of curves, the order of the junctions, and the angles between curves at the junctions. Since this class lacks compactness, we characterize the set of limits of sequences of networks bounded in energy, providing an explicit representation of the relaxed problem. This is expressed in terms of the new notion of degenerate elastic networks that, rather surprisingly, involves only the properties of the given class, without reference to the curvature.

Lifestyle and psychological factors related to irritable bowel syndrome in nursing and medical school students.

Background: Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder comprising abdominal pain, abdominal discomfort, and disordered defecation. The prevalence of IBS is 10-15% in the general population. This study investigated the prevalence of IBS and the relationship between IBS and stress, lifestyle, and dietary habits among nursing and medical school students.