How to automate a kinematic mount using a 3D printed Arduino-based system

We demonstrate a simple, flexible and cost-effective system to automatize most of the kinematic mounts available nowadays on the market. It combines 3D printed components, an Arduino board, stepper motors, and simple electronics. The system developed can control independently and simultaneously up to ten stepper motors using commands sent through the serial port, and it is suitable for applications where optical realignment using flat mirrors is required on a periodic basis.Comment: 9 pages, 8 figure

Optical sectioning in induced coherence tomography with frequency-entangled photons

We demonstrate a different scheme to perform optical sectioning of a sample based on the concept of induced coherence [Zou et al., Phys. Rev. Lett. 67, 318 (1991)]. This can be viewed as a different type of optical coherence tomography scheme where the varying reflectivity of the sample along the direction of propagation of an optical beam translates into changes of the degree of first-order coherence between two beams. As a practical advantage the scheme allows probing the sample with one wavelength and measuring photons with another wavelength. In a bio-imaging scenario, this would result in a deeper penetration into the sample because of probing with longer wavelengths, while still using the optimum wavelength for detection. The scheme proposed here could achieve submicron axial resolution by making use of nonlinear parametric sources with broad spectral bandwidth emission.Comment: Published version. 11 pages, 9 figure

Weak value amplification : new insights and applications

Weak Value Amplification (WVA) is a signal enhancement technique proposed in 1988 by Aharonov, Albert, and Vaidman that has been widely used to measure tiny changes that otherwise cannot be determined because of technical limitations. It is based on: i) the existence of a weak interaction which couples a property of a system (the system) with a separate degree of freedom (the pointer), and ii) the measurement of an anomalously large mean value of the pointer state (weak mean value), after appropriate pre and post-selection of the state of the system. The usefulness of weak value amplification for measuring extremely small quantities has been demonstrated under a great variety of experimental conditions to measure very small transverse displacements of optical beams, beam deflections, angular shifts, temporal shifts, phase shifts, frequency shifts, velocity measurements and temperature differences, among others. In this thesis we make use of this concept to improve current technologies and analyse the true usefulness of this technique with respect to other experimental alternatives. In particular, we have applied the concept to measure femtosecond temporal delays between pulses much smaller than their pulse width. From the theoretical model we estimate that the ultimate sensitivity of this scheme will allow to measure delays of the order of attoseconds using femtosecond laser sources. In addition, we have developed an innovative experimental scheme that makes use of the interference effect present in a WVA scheme to generate a highly-sensitive tunable beam displacer that can outperform the limitations imposed by the use of movable optical elements. From the experimental results, we were able to perform a scan of a Gaussian beam with waist 600 μm over an interval of 240 μm in steps of 1 μm. Moreover, we have implemented a proof-of-concept experiment aimed at increasing the sensitivity of Fiber Bragg Grating (FBG) temperature sensors. The sensors behave as frequency filters whose center is determined by its surrounding temperature. By means of a WVA scheme we were able to measure a polarization dependent frequency shift that is small compared to the width of each FBG spectrum, and from that value we were able to obtain a four-fold enhancement of the sensitivity with respect to current schemes. Finally, we address the question of what can offer the concept of WVA and what can not in terms of achieving high sensitivity measurements. By using a specific example and some basic concepts from quantum estimation theory, we have found that while WVA cannot be used to go beyond some fundamental sensitivity limits that arise from considering the full nature of the quantum states, WVA can notwithstanding enhance the sensitivity of real and specific detection schemes that are limited by many other things apart from the quantum nature of the states involved, i.e. technical noise.Weak Value Amplification (WVA) es una técnica experimental propuesta en 1988 por Aharonov, Albert, y Vaidman que ha sido ampliamente utilizada para medir pequeños cambios de variables físicas que en principio no podrían medirse usando otras metodologías debido a limitaciones técnicas. La técnica se basa en: i) la existencia de una interacción débil que acopla una propiedad de un sistema (el sistema) con otro grado de libertad (el metro), y ii) la medición de un valor promedio particularmente grande del metro (weak mean value), después de realizar una selección adecuada de los estados inicial y final del sistema. La utilidad de la técnica para la medición de cantidades extremadamente pequeñas ha sido demostrada en una gran variedad de condiciones experimentales para medir, por ejemplo, desplazamientos transversales de haces ópticos muy pequeños, deflexiones en haces, corrimientos angulares, retardos temporales, cambios de fase, cambios de frecuencia, mediciones de velocidad y diferencias de temperaturas, entre otros. En esta tesis, hacemos uso del concepto de Weak Value Amplification para mejorar el desempeño de algunos esquemas experimentales actuales y también para analizar la verdadera utilidad de esta técnica con respecto a otras alternativas experimentales. En particular, aplicamos el concepto para medir retardos temporales entre pulsos del orden de femtosegundos mucho más pequeños que su duración y mediante un modelo teórico, determinamos un límite en la sensibilidad del sistema que permite medir retardos del orden de attosegundos utilizando pulsos del orden de femtosegundos. También desarrollamos un dispositivo que hace uso de la interfencia presente en los esquemas basados en WVA para generar un desplazador de haz sintonizable que puede superar las limitaciones impuestas en resolución por el uso de elementos ópticos móviles. En particular, reportamos el resultado de realizar un barrido de la posición de un haz Gaussiano, con ancho 600 μm, a lo largo de un intervalo de 240 μm en pasos de 1 μm. Por otro lado, demostramos la viabilidad del uso del concepto de WVApara aumentar la sensibilidad en sensores de temperatura basados en Fiber Bragg Gratings (FBG) a través de un experimento. Teniendo en cuenta de que este tipo de sensores se comportan como filtros espectrales cuya frecuencia central está determinada por la temperatura a su alrededor, con el esquema implementado, hemos podido medir corrimientos en frecuencia que son pequeños en comparación con el ancho del espectro de cada FBG. En particular reportamos que el esquema implementado permite mejorar en un factor de cuatro la sensibilidad de los esquemas de medición corrientes. Por último, buscamos dar respuesta a la pregunta: ¿qué puede y qué no puede ofrecer el concepto de WVA cuando se utiliza en mediciones de gran precisión? Mediante el uso de un ejemplo especifico y algunos conceptos básicos de la mecánica cuántica, hemos encontrado que los esquemas basados en WVA no son de utilidad para superar limites fundamentales que surgen al considerar la naturaleza cuántica de la luz. Sin embargo, hemos encontrado que el concepto de WVA puede ser de gran utilidad para mejorar la sensibilidad de esquemas experimentales específicos en donde la sensibilidad puede estar limitada por otros factores diferentes a la naturaleza cuántica de la luz, como por ejemplo el ruido técnico.Postprint (published version

Tunable beam displacer

We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.Comment: 3 pages, 2 figure

Demonstration of a highly-sensitive tunable beam displacer with no use of beam deflection based on the concept of weak value amplification

We report the implementation of a highly sensitive tunable beam displacer based on the concept of weak value amplification, that allows to displace the centroid of a Gaussian beam a distance much smaller than its beam width without the need to deflect the direction of propagation of the input beam with movable optical elements. The beam’s centroid position can be displaced by controlling the linear polarization of the output beam, and the dependence between the centroid’s position and the angle of polarization is linear.Peer ReviewedPostprint (published version

A Comparison of Nutritional Habits, Physical Function and Psychological Constructs between Urban and Rural Costa Rican Older Adults

Purpose: To compare nutritional habits, physical function and psychological constructs between Costa Rican older adults from urban and rural zones.Methods: Male and female older adults aged ? 65 yr. from urban (n = 185) and rural (n = 109) Costa Rica were assessed on nutritional habits, physical function measures, and cognitive function by a face-to-face interview.Results: Rural older adults consumed more daily carbohydrates, protein, and energy at breakfast and lunch (p < 0.05 for all), and more carbohydrates (p ? 0.001), fat (p = 0.002), protein (p ? 0.001), and energy (p ? 0.001) at dinner than urban elderly. Aerobic power (p = 0.044) was higher in urban compared to rural elderly. A correlation was found between aerobic power and global fatigue (r = -0.20, p = 0.014) in urban elderly. Lifetime cognitive activity correlated to total energy (r = 0.37, p = 0.003), carbohydrate (r = 0.37, p = 0.002), and protein (r = 0.34, p = 0.005) consumption in rural elderly. Higher depression scores (p = 0.048), and lower lifetime cognitive activity were observed in urban compared to rural elderly (p = 0.004).Conclusion: The health profile is positive for either group depending on the variable analyzed, except for a higher aerobic power, which provides benefits to the entire cohort

QGIS a constantly growing free and open-source geospatial software contributing to scientific development

QGIS is the most popular free geospatial software in the world. QGIS belongs to the Open-Source Geospatial Foundation (OSGeo). Among the main strengths of this Geographic Information Systems are: the incorporation of tools via plugins, and a community of users and developers in constant growth. Despite the importance on the use of QGIS on the scientific community, to date there are no systematic studies indicating how the acceptance of this software has evolved through time. Therefore, the objective of this research was to characterize the scientific production and extent where QGIS has been used as their main geospatial tool. We conducted a bibliometric analysis of documents published in Scopus from 2005 to 2020 (931 manuscripts). The annual rate of publications increase was 40.3%. We found strong and positive correlations regarding the number of contributing code programmers (r=0.66, p<0.005); and the total income of the QGIS project (r=0.88, p<0.001). Seventy-two percent of the publications were included in six fields of study, being Earth and Planetary Sciences the most representative. Italy was the country with larger scientific production, while the USA was the most influential country (being the first, regarding the number of citations). In terms of the countries, the larger number of papers found were from Portugal, Italy, Brazil, and France. The International Archives of the Photogrammetry Remote Sensing and Spatial Information Sciences - ISPRS Archives stands among journals with the largest number of publications (47). In terms of collaborative networks among countries, we found strong links between authors from Germany, Switzerland, Greece, and Spain. Author network analysis showed three solid networks in different fields of study. We observed a favorable trend in the acceptance of QGIS across the world and a widespread development of collaborative networks. The present paper allowed increase the knowledge of geographic information systems, especially the development of scientific production using QGIS

A Comparison of Nutritional Habits, Physical Function and Psychological Constructs between Urban and Rural Costa Rican Older Adults

Purpose: To compare nutritional habits, physical function and psychological constructs between Costa Rican older adults from urban and rural zones. Methods: Male and female older adults aged ≥ 65 yr. from urban (n = 185) and rural (n = 109) Costa Rica were assessed on nutritional habits, physical function measures, and cognitive function by a face-to-face interview. Results: Rural older adults consumed more daily carbohydrates, protein, and energy at breakfast and lunch (p < 0.05 for all), and more carbohydrates (p ≤ 0.001), fat (p = 0.002), protein (p ≤ 0.001), and energy (p ≤ 0.001) at dinner than urban elderly. Aerobic power (p = 0.044) was higher in urban compared to rural elderly. A correlation was found between aerobic power and global fatigue (r = -0.20, p = 0.014) in urban elderly. Lifetime cognitive activity correlated to total energy (r = 0.37, p = 0.003), carbohydrate (r = 0.37, p = 0.002), and protein (r = 0.34, p = 0.005) consumption in rural elderly. Higher depression scores (p = 0.048), and lower lifetime cognitive activity were observed in urban compared to rural elderly (p = 0.004). Conclusion: The health profile is positive for either group depending on the variable analyzed, except for a higher aerobic power, which provides benefits to the entire cohort.National Institutes of Health/[R21TW009665]/NIH/Estados UnidosNational Institute of Aging/[P30AG010129]/NIA/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Centro de Investigación en Ciencias del Movimiento Humano (CIMOHU)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

Avances científicos del búho manchado mexicano (Strix occidentalis lucida Nelson 1903)

Objective: Evaluate quantitatively the research trends of the Mexican Spotted Owl. Design/methodology/approach: Scientific articles published between 2012 and February 2020 for the Mexican spotted owl were analyzed. The content of each article was classified into nine categorical variables: 1) biological description, 2) habitat, 3) distribution and abundance, 4) dispersion and movement, 5) diet and prey, 6) genetics and reproduction, 7) threats, 8) predictive models and 9) others. The published information was classified into similar groups by means of a hierarchical cluster analysis. Subsequently, were calculated and graphed the frequency and proportional representation of each attribute generated by country. Results: Of the 23 scientific articles analyzed, the most studied attribute was habitat. The hierarchical cluster analysis grouped all the published information into five representative topics: a) habitat relationships, b) threats, c) distribution, d) bibliographic review and e) population relationship. The United States was the country with the highest scientific contribution. However, in the last three years of the period studied, publications in Mexico increased. Limitations on study/implications: This study analyzes the research trends of the Mexican spotted owl and provides an overview for future research. Findings/conclusions: There is little published information for this spotted owl subspecies. Although the characteristics of the habitat are widely described; it is necessary to venture into more complex ecological phenomena.Objetivo: Evaluar cuantitativamente las tendencias de la investigación del Búho Manchado Mexicano. Diseño/metodología/aproximación: Se analizaron los artículos científicos publicados entre 2012 y febrero de 2020 para el búho manchado mexicano. El contenido de cada artículo se clasificó en nueve variables categóricas: 1) descripción biológica, 2) hábitat, 3) distribución y abundancia, 4) dispersión y movimiento, 5) dieta y presas, 6) genética y reproducción, 7) amenazas, 8) modelos predictivos y 9) otros. La información publicada, se clasificó en grupos similares mediante un análisis de conglomerado jerárquico. Posteriormente, se calcularon y graficaron la frecuencia y representación proporcional de cada atributo generado por país. Resultados: De los 23 artículos científicos analizados, el atributo más estudiado fue el hábitat. El análisis de conglomerados jerárquicos agrupó toda la información publicada en cinco temas representativos:&nbsp; a) relaciones del hábitat, b) amenazas, c) distribución, d) revisión bibliográfica y e) relación de las poblaciones. Estados Unidos fue el país con mayor contribución científica. Sin embargo, en los últimos tres años del periodo estudiado, las publicaciones en México incrementaron. Limitaciones del estudio/implicaciones: Este estudio analiza las tendencias de investigación del búho manchado mexicano y permite establecer un panorama para investigaciones futuras. Hallazgos/conclusiones: Existe poca información publicada para esa subespecie de búho manchado. Aunque las características del hábitat son ampliamente descritas; es necesario incursionar en fenómenos ecológicos más complejos