Nonlinear and Quantum Optics with Whispering Gallery Resonators

Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.Comment: This is a review paper with 615 references, submitted to J. Op

Epidemic processes in complex networks

In recent years the research community has accumulated overwhelming evidence for the emergence of complex and heterogeneous connectivity patterns in a wide range of biological and sociotechnical systems. The complex properties of real-world networks have a profound impact on the behavior of equilibrium and nonequilibrium phenomena occurring in various systems, and the study of epidemic spreading is central to our understanding of the unfolding of dynamical processes in complex networks. The theoretical analysis of epidemic spreading in heterogeneous networks requires the development of novel analytical frameworks, and it has produced results of conceptual and practical relevance. A coherent and comprehensive review of the vast research activity concerning epidemic processes is presented, detailing the successful theoretical approaches as well as making their limits and assumptions clear. Physicists, mathematicians, epidemiologists, computer, and social scientists share a common interest in studying epidemic spreading and rely on similar models for the description of the diffusion of pathogens, knowledge, and innovation. For this reason, while focusing on the main results and the paradigmatic models in infectious disease modeling, the major results concerning generalized social contagion processes are also presented. Finally, the research activity at the forefront in the study of epidemic spreading in coevolving, coupled, and time-varying networks is reported.Comment: 62 pages, 15 figures, final versio

Structural studies of filamentous plant viruses by cryo-electron microscopy and cryo-electron tomography

139 p.Los virus filamentosos flexibles de plantas representan un grupo de patógenos de plantas que causan un gran impacto económico en cultivos dedicados a la agricultura. El géneropotyvirus es el más numeroso y abarca hasta un tercio de las especies de virus conocidas.El principal objetivo de este trabajo es la obtención de más información estructural sobre los virus filamentosos flexibles de plantas, usando las metodologías de crio-microscopía electrónica (crio-ME) y crio-tomografía electrónica (crio-TE).En éste trabajo, la estructura del virus del mosaico del nabo (Turnip mosaic virus, TuMV) ha sido resuelta a 5 Å mediante crio-ME, así como la estructura de sus partículas como virus (Viral like particles, VLPs) a resoluciones entre 7 y 8 Å. Mediante crio-TE se ha explorado la estructura de los extremos de los filamentos, encontrando dos estructuras diferenciadas, una con forma de hélice y otra con un final plano con una densidad alargada adicional que podría pertenecer a otra proteína potyviral, la VPg.Finalmente, se ha realizado la búsqueda de compuestos químicos que interaccionan al bolsillo de unión de la proteína de la cápside con el ssRNA mediante técnicas de resonancia magnética nuclear (RMN) y se estudió la naturaleza de la interacción mediante crio-ME.CICbioGUN