A compact theoretical description of the effects of dissipation on the propagation of light waves through a multilayer periodic mirror built from resonant absorbing atoms is presented. Depending on the lattice periodicity, ultranarrow photonic gaps, weak polaritonic gaps, as well as rather atypical gap structures may be observed. Because of the atom's absorption line shape Bloch gap modes may acquire quite a cumbersome structure which is thoroughly studied here or which may even disappear when dissipation becomes sufficiently strong. The same approach well applies also to resonantly absorbing photonic crystals based on excitonic resonances.

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Background The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has an impact also on neurosurgical training and education, especially in most affected countries. We surveyed Italian neurosurgical residents, asking them to provide a brief description and analyze the situation they are experiencing and how the educational system reacted to the pandemic in one of the most affected countries all over the world. Methods An 18-question, web-based survey was administered to Italian neurosurgical residents from May 3 to May 11, 2020, by web-link or e-mail invitation. Closed-ended, multiple choice questions were focused on the experience of neurosurgical residents in the last 2 months (from March to May 2020) concerning both clinical and educational aspects. Results Among 331 Italian neurosurgical residents invited to participate, 192 responded to the survey (58%). According to the participants' responses, in the whole country, only 29.7% of residents were directly involved in the clinical management of COVID-19 patients. Time spent in the clinic and surgical activity was significantly reduced in most of the cases. Educational activities as well as scientific activity and time spent for studying, on the other hand, were reported to be significantly increased by the majority of respondents. Conclusions Most Italian neurosurgical residents reported significant changes on both training and education, highlighting a prompt reaction of the educational system in the whole country, regardless the local and regional diffusion of the pandemic.

The motivation of this work fits with the general vision to enable e-health for European citizens, irrespective of their social and financial status and their place of residence. Services to be provided include access to a high-quality early diagnostic and prognostic service for the Alzheimer Disease and other forms of dementia, based both on the European Research and Education Networks and the European Grid Infrastructure. The present paper reports on the architecture and V. Ardizzone (B) · E. Ingrà · R. Rotondo