Probing Quantum Optical Excitations with Fast Electrons

Probing optical excitations with nanometer resolution is important for understanding their dynamics and interactions down to the atomic scale. Electron microscopes currently offer the unparalleled ability of rendering spatially-resolved electron spectra with combined meV and sub-nm resolution, while the use of ultrafast optical pulses enables fs temporal resolution and exposure of the electrons to ultraintense confined optical fields. Here, we theoretically investigate fundamental aspects of the interaction of fast electrons with localized optical modes that are made possible by these advances. We use a quantum-optics description of the optical field to predict that the resulting electron spectra strongly depend on the statistics of the sample excitations (bosonic or fermionic) and their population (Fock, coherent, or thermal), whose autocorrelation functions are directly retrieved from the ratios of electron gain intensities. We further explore feasible experimental scenarios to probe the quantum characteristics of the sampled excitations and their populations.Comment: 13 pages, 6 figures, 56 reference

Using ORB, BoW and SVM to identify and track tagged Norway lobster Nephrops norvegicus (L.)

Sustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically available.Peer Reviewe

La humedad como factor de fertilidad : su influencia en la nutrición vegetal : (nueva teoría para generalizar la Ley del Mínimo)

Tesis inédita de la Universidad de Madrid, Facultad de Ciencias, leída el 14 de julio de 1967.Universidad de MadridTRUEProQuestpu

Electron diffraction by vacuum fluctuations

Vacuum fluctuations are known to produce electron diffraction leading to decoherence and self-interference. These effects have so far been studied as either an extension of the Aharonov–Bohm effect in front of a planar perfect conductor or through path integral analysis. Here, we present a simpler, general, and rigorous derivation based on a direct solution of the quantum electrodynamic aloof interaction between the electron and a material structure in the temporal gauge. Our approach allows us to study dissipative media, for which we show examples of electron wave function shaping due to the interaction with real-metal surfaces. We further present a proof of the relation between the phase associated with vacuum fluctuations and the Aharonov–Bohm effect produced by the image self-interaction that is valid for arbitrary geometries. Besides their fundamental interest, our results could be useful for on-demand patterning of electron beams with potential application in nondestructive nanoscale imaging and spectroscopy.Peer ReviewedPostprint (published version

Nanophotonics for pair production

The transformation of electromagnetic energy into matter represents a fascinating prediction of relativistic quantum electrodynamics that is paradigmatically exemplified by the creation of electron-positron pairs out of light. However, this phenomenon has a very low probability, so positron sources rely instead on beta decay, which demands elaborate monochromatization and trapping schemes to achieve high-quality beams. Here, we propose to use intense, strongly confined optical near fields supported by a nanostructured material in combination with high-energy photons to create electron-positron pairs. Specifically, we show that the interaction between near-threshold gamma-rays and polaritons yields higher pair-production cross sections, largely exceeding those associated with free-space photons. Our work opens an unexplored avenue toward generating tunable pulsed positrons at the intersection between particle physics and nanophotonics.Comment: 15 pages, 6 figures, 55 reference

Using ORB, BoW and SVM to identify and track tagged Norway lobster Nephrops norvegicus (L.)

7th International Workshop on Marine Technology – Martech Workshop 2016, 26-28 October 2016, Barcelona.-- 3 pages, 4 figures, 1 tableSustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically availablePeer Reviewe

Experiencia de turismo en la Reserva Natural Complejo Volcánico Pilas el Hoyo en el período de Agosto a Diciembre del 2016

El departamento de León ubicado en el occidente del país, es un departamento con gran variedad de atractivos naturales, en el cual encontramos la Reserva natural complejo volcánico Pilas- El hoyo, el cual es un sitio de interés turístico para los amantes de la Naturaleza y aventura extrema. Pilas El Hoyo se encuentra ubicada en la región del pacifico de Nicaragua localizándose en el departamento de león, el área protegida limita al sur y al este con el municipio de la paz centro al norte y al este con el municipio de Larreynaga y al oeste con el municipio de león y con el municipio de Larreynaga Esta área protegida Fue creada bajo el decreto 1320 creación de reservas naturales en el pacifico de Nicaragua del 19 de septiembre de 1983 publicado en la gaceta diario oficial número 213. Esta imponente Reserva natural complejo volcánico poseedora de varios edificios volcánicos los cuales comparten una misma base, Siendo en este el más destacado el volcán pilas con una altura de 1,008 y el volcán hoyo con una altura de 1, 089 metros y el cerro negro volcán más joven y activo con 726 metros de altura siendo este su principal atractivo este volcán tuvo su última erupción en el año 1999. Para la realización de esta investigación se aplicó la metodología de tipo descriptivo, con enfoque cualitativo, describiéndose las características del lugar a partir de la observación durante el trabajo de campo entrevistas aplicadas y observación directa a participantes. Esta Reserva se eligió para la realización de seminario de graduación la cual lleva por título Propuestas de Mejoras, para el Desarrollo Turístico Sostenible en la Reserva Natural Complejo Volcánico Pilas el Hoyo en el período de Agosto a Diciembre del 2016. El presente documento fue realizado con el fin de que en la reserva exista un mejor aprovechamiento de los recursos naturales estableciendo planes estratégicos para un mejor funcionamiento. Esta investigación contiene un análisis FODA el cual muestra el análisis interno y externo de la reserva natural complejo volcánico Las Pilas- El Hoyo En lo