Theory of extraordinary transmission of light through quasiperiodic arrays of subwavelength holes

By using a theoretical formalism able to work in both real and k-spaces, the physical origin of the phenomenon of extraordinary transmission of light through quasi-periodic arrays of holes is revealed. Long-range order present in a quasiperiodic array selects the wavevector(s) of the surface electromagnetic mode(s) that allows an efficient transmission of light through subwavelength holes.Comment: 4 pages, 4 figure

Resonant transmission of light through finite chains of subwavelength holes

In this paper we show that the extraordinary optical transmission phenomenon found before in 2D hole arrays is already present in a linear chain of subwavelength holes, which can be considered as the basic geometrical unit showing this property. In order to study this problem we have developed a new theoretical framework, able to analyze the optical properties of finite collections of subwavelength apertures and/or dimples (of any shape and placed in arbitrary positions) drilled in a metallic film.Comment: Accepted for publication in Phys. Rev. Let

Identificación de tipologías estructurales con el Inventario Forestal Nacional: el caso de los robledales albares en la Cordillera Cantábrica

The objective of this work was the creation of a structural stand classification for sessile oak dominated forests in the Cantabrian Range (northern Spain) as a basic tool for typological inventories. A dichotomous classification system and discriminant classification equations of nine forest types were defined with an accuracy of more than 95% by evaluating the data of the second Spanish National Forest Inventory (SNFI). The presence of large old trees appears as one of the main characteristics of the Cantabrian sessile oak forests. The structure assessment method presented in this study, based on a dataset (SNFI) and free-access software, can be considered an important low-cost alternative to traditional quantitative inventory methods.El objeto de este trabajo ha sido la elaboración de una clasificación tipológica para robledales cantábricos (norte de España) como herramienta base de inventario tipológico. Tomando como base de datos el inventario forestal nacional español (IFN) y con una fiabilidad superior al 95% se elaboran una clave de clasificación dicotómica y ecuaciones discriminantes de clasificación para nueve tipos estructurales de masa. La presencia de viejos robles de grandes diámetros aparece como uno de los rasgos diferenciales de los robledales cantábricos. La metodología de evaluación de la estructura forestal elaborada en el presente estudio, basada en una base de datos de libre acceso (IFN) y en un software gratuito, puede ser entendida como una alternativa de bajo coste al inventario cuantitativo tradicional

Classical Antiferromagnetism in Kinetically Frustrated Electronic Models

We study the infinite U Hubbard model with one hole doped away half-filling, in triangular and square lattices with frustrated hoppings that invalidate Nagaoka's theorem, by means of the density matrix renormalization group. We find that these kinetically frustrated models have antiferromagnetic ground states with classical local magnetization in the thermodynamic limit. We identify the mechanism of this kinetic antiferromagnetism with the release of the kinetic energy frustration as the hole moves in the established antiferromagnetic background. This release can occurs in two different ways: by a non-trivial spin-Berry phase acquired by the hole or by the effective vanishing of the hopping amplitude along the frustrating loops.Comment: 12 pages and 4 figures, with Supplementary Material. To be published in Phys. Rev. Let