Rainbow trapping in a chirped three-dimensional photonic crystal

Light localization and intensity enhancement in a woodpile layer-by-layer photonic crystal, whose interlayer distance along the light propagation direction is gradually varied, has been theoretically predicted and experimentally demonstrated. The phenomenon is shown to be related to the progressive slowing down and stopping of the incident wave, as a result of the gradual variation of the local dispersion. The light localization is chromatically resolved, since every frequency component is stopped and reflected back at different positions along the crystal. It has been further discussed that the peculiar relation between the stopping position and the wave vector distribution can substantially increase the enhancement factor to more than two orders of magnitude. Compared to previously reported one-and two-dimensional photonic crystal configurations, the proposed scheme has the advantage of reducing the propagation losses by providing a three-dimensional photonic bandgap confinement in all directions. The slowing down and localization of waves inside photonic media can be exploited in optics and generally in wave dynamics, in many applications that require enhanced interaction of light and matter.Authors acknowledge financial support of NATO SPS research grant No: 985048. K.S. acknowledges financial support of Spanish Ministerio de Ciencia e Innovacion and European Union FEDER through project FIS2015-65998- C2-1-P. H.K. also acknowledges partial support of the Turkish Academy of Science

Coronary microvascular dysfunction in cardiovascular disease:Lessons from large animal models

The coronary microvasculature is responsible for maintaining local matching of myocardial blood flow to myocardial demand of oxygen and nutrients. Long term adjustment of myocardial blood flow involves structural changes in microvascular density and diameter while fine-tuning of flow is achieved via adaptations in vascular smooth muscle tone in the coronary microvasculature.In the past several decades, considerable research efforts have been directed at understanding structural and functional microvascular adaptations involved in matching myocardial oxygen supply and demand and how these mechanisms are affected by various diseases. In this review we will discuss our current understanding of the mechanisms underlying the regulation of coronary microvascular tone under healthy physiological conditions, and the role of microvascular dysfunction in obstructive and non-obstructive coronary artery disease, as studied in large animal (particularly swine) models and confirmed in human studies. Future studies should be directed at further unraveling the mechanisms of coronary microvascular dysfunction in different disease entities in order to, and ultimately directed at improving microvascular function as a therapeutic target in patients with ischemic heart disease