Probing ultra-subwavelength inhomogeneities embedded within dielectric targets using photonic nanojets

The use of optics to detect ultra-subwavelength features embedded within structures is a hot topic for a broad diversity of applications like spectroscopy, nanotechnology, microscopy, and optical data storage discs. Conventional objective lens based optical systems have a fundamental limit on the best possible resolution of about 200 \u03b7m due to the diffraction of light as it propagates into the far-field. There already exist several near-field techniques with the capability to overcome this limitation, but each of these systems has certain drawbacks related to the complexity of the system or to limitations imposed by the system. A photonic nanojet is a very particular beam of light that can provide a practical way to overcome the diffraction limit inherent to far-field techniques. A nanojet is an electromagnetic field envelope formed on the shadow-side surface of a plane-wave-illuminated dielectric microsphere of diameter larger than the wavelength and with refractive index contrast relative to the background medium of less than 2:1. It can maintain a subwavelength transversal beamwidth for distances greater than 2 wavelengths away from the surface of the generating microsphere. This Dissertation provides a computational test of the hypothesis that the backscattered spectrum resulting from photonic nanojet illumination of a three-dimensional (3-D) dielectric structure can reveal the presence and location of ultra-subwavelength, nanoscale-thin weakly contrasting dielectric inhomogeneities within dielectric targets. The effect of surface roughness on the illuminated side of the target is analyzed, and targets ranging from simple dielectric slabs to complex biological cells are studied. The present work is performed through computational electrodynamics modeling based upon the rigorous, large-scale solution of Maxwells equations. Specifically, the 3-D finite-difference time-domain (FDTD) method is employed to test the above hypothesis.\u2

Innovación digital en el aula de matemáticas: desarrollo de materiales docentes como apoyo en la enseñanza

La propuesta que se presenta forma parte de un proyecto de innovación docente, vinculado al servicio de producción e innovación digital de la Universidad de Salamanca, desarrollado en el curso 2015-16. En la asignatura de Matemáticas, cuyos contenidos tratan sobre Geometría y su didáctica, se generaron vídeos teórico prácticos, centrados en el recurso didáctico de la papiroflexia

Techno-Educational Conditions in Mexico Before and During the Pandemic: Moving Towards the Necessary Consolidation of a Digital Education Agenda

This article provides a contextualization of the conditions prior to the pandemic in the Mexican educational system, in particular the programs and educational technologies implemented by the authorities to provide continuity of learning. With this, the actions and mechanisms of students and teachers in the use of information, communication, knowledge and digital learning technologies for the use of multimedia and interactive content are identified. From there, the strategies to provide schools and students with computers, laptops and tablets and Internet connectivity are considered. The results of the research provide a glimpse of those actions that are part of the necessary consolidation of a Digital Education Agenda

Detection of embedded ultra-subwavelength-thin dielectric features using elongated photonic nanojets

pre-printPhotonic nanojets have been previously shown (both theoretically and experimentally) to be highly sensitive to the presence of an ultra-subwavelength nanoscale particle within the nanojet. In the present work, photonic nanojets elongated by almost an order of magnitude (relative to the latest previously published work) are found to possess another key characteristic: they are sensitive to the presence of ultra-subwavelength nanoscale thin features embedded within a dielectric object. This additional characteristic of photonic nanojets is demonstrated through comparisons between fundamentally different 3-D and corresponding 1-D full Maxwell's equations finite-difference time-domain (FDTD) models

Obtención de aceite de orujo

Pomace oil is the principal by-product in olive oil processing and is currently developing considerably due to the technological advances which the mills have undergone in recent years. This investigation aims at presenting an overview of the complexity of this sector which, with around 100 years of existence, is searching for a role in the new integral strategy of the olive oil industry after the crisis suffered in 2001. Physical extraction, drying and solvent extraction are discussed, along with the influence of the technological treatments on the chemical composition of pomace oil.El aceite de orujo es el principal subproducto en el procesado de aceite de oliva y su obtención se ha transformado considerablemente en los últimos tiempos debido a los avances tecnológicos que han experimentado las almazaras. Este trabajo tiene la finalidad de presentar una panorámica de la complejidad de este sector, de casi 100 años de existencia, que se afana en encontrar su función dentro de la nueva estrategia integral de la industria oleícola después de la crisis sufrida en el año 2001. En el mismo se comentan la extracción física, el secado, así como la extracción con disolvente, y la influencia que tienen los tratamientos tecnológicos sobre la composición química del aceite de orujo.Peer reviewe

Desarrollo de habilidades cognitivas y metacognitivas que conlleven a un pensamiento inteligente en la aplicación de estrategias para la resolucion de problemas sociales y de razonamiento en estudiantes de tercer grado de la Escuela Miguel Obregon Lizano del circuito 02 de la Direccion Regional de Alajuela

Trabajo final de graduación de 185 páginas en formato pdfEl propósito de este trabajo de investigación fue desarrollar y determinar el efecto de una intervención psicopedagógica mediante un taller que promoviera las habilidades cognitivas y metacognitivas para la aplicación de estrategias en la resolución inteligente de problemas sociales y de razonamiento. Diseño del estudio: Un diseño cuasiexperimental fue utilizado durante 4 meses. Sujetos: 26 niños en el grupo experimental y 26 niños en el grupo control, con edades que oscilan entre los 8 y los 10 años. La intervención fue conducida por las investigadoras directamente, con el apoyo asistencial de la maestra de grupo.y utilizando actividades varias que ejercitaban el desarrollo de 7 operaciones cognitivas: recuperar información. Comparar, contextualizar, estructurar, inferir, comunicar y metacognición. Resultados: Los participantes en el grupo de intervención tuvieron un incremento significativo en la aplicación de estrategias cognitivas y metacognitivas en la resolución de problemas sociales y de razonamiento. Conclusiones: El Taller de habilidades cognitivas y metacognitivas mejoró la capacidad, la actitud, el pensamiento analítico, la toma de decisiones y el nivel de funcionamiento de los niños y niñas de tercer nivel en la resolución inteligente de problemas sociales y de razonamiento, además de otras habilidades implícitas en cada operación cognitiva tales como: seguimiento de instrucciones, atención, concentración y trabajo cooperativo.Universidad Estatal a Distancia de Costa Ric

PCA based stress monitoring of cylindrical specimens using PZTs and guidedwaves

Since mechanical stress in structures affects issues such as strength, expected operational life and dimensional stability, a continuous stress monitoring scheme is necessary for a complete integrity assessment. Consequently, this paper proposes a stress monitoring scheme for cylindrical specimens, which are widely used in structures such as pipelines, wind turbines or bridges. The approach consists of tracking guided wave variations due to load changes, by comparing wave statistical patterns via Principal Component Analysis (PCA). Each load scenario is projected to the PCA space by means of a baseline model and represented using the Q-statistical indices. Experimental validation of the proposed methodology is conducted on two specimens: (i) a 12.7 mm (1/2”) diameter, 0.4 m length, AISI 1020 steel rod, and (ii) a 25.4 mm (1”) diameter, 6m length, schedule 40, A-106, hollow cylinder. Specimen 1 was subjected to axial loads, meanwhile specimen 2 to flexion. In both cases, simultaneous longitudinal and flexural guided waves were generated via piezoelectric devices (PZTs) in a pitch-catch configuration. Experimental results show the feasibility of the approach and its potential use as in-situ continuous stress monitoring application.Peer ReviewedPostprint (published version

Intraocular pressure reactivity to social stressors: the role of self-efficacy, perceived threat, and aversiveness of non-contact tonometry

A field study was carried out in an optometry clinic, aimed at assessing the role of perceived control and aversiveness of noncontact tonometry in intraocular pressure (IOP) reactivity to psychosocial stressors, and analyzing the covariation with cardiovascular and affective reactivity. Forty-four customers volunteered to participate in the study. Perceived control (self efficacy and threat) was assessed at the onset. IOP, systolic and diastolic blood pressure, heart rate, affect, and aversiveness of the IOP measurement procedure were assessed throughout five phases with a mean duration for each phase of 9 min: arrival, optometry, baseline, stressor task (speech in public task), and recovery. The results suggest that IOP decreases over time and the stressor task induced a remarkable reactivity in all the physiological variables assessed. The interaction between self-efficacy and threat partially explains individual variability in IOP: a high threat combined with a high self-efficacy yielded higher reactivity in IOP or increased tonic values throughout the phases. The aversiveness of the measurement procedure did not affect IOP. Intraocular Pressure (IOP) is reactive to social stressors and perceived control partially explains individual variability. Cardiovascular and IOP reactivity are parallel phenomena but do not share a common regulatory mechanism