Ferroelectric Tunnel Junctions

Ferroelectricity and quantum-mechanical electron tunneling are well-known physical phenomena that have been studied for as long as a century. During this long period, scientific research has been restricted either to ferroelectricity or to electron tunneling. Never before have these subjects been combined into a new phenomenon based on their interaction. Within this work, I present the novel concept of a ferroelectric tunnel junction, where the term ferroelectric refers to a property of the barrier material. This device consists of a ferroelectric layer sandwiched between metal electrodes. The thickness of the ferroelectric layer is thin enough to allow for electron tunneling. For the first time, the influence of macroscopic parameters, such as the spontaneous polarization and strain on quantum-mechanical electron tunneling through a ferroelectric tunnel barrier is studied experimentally. In addition, the experimental work is accompanied by theoretical ideas and predictions concerning the manifestation of piezoelectricity or ferroelectricity in direct electron tunneling

Rapid, Diagnostic Test for Cardiac Ischemia

Current methods to detect cardiac ischemia rely on biomarkers such as troponin. Elevated levels of troponin are observed hours after the cardiac event. There is an unmet need for rapid diagnostic tests for cardiac ischemia, which utilizes recently discovered biomarkers. A VCU patented assay for cardiac ischemia employs the use of chemiluminescence to detect metabolic byproducts of xanthine oxidase activity. These byproducts are detectable minutes after the cardiac event. Early diagnosis of and response to cardiac events is beneficial for clinical decision-making; therefore, a point-of-care device within the emergency health setting is sought. The CLSE 203 project team designed and fabricated a multi-layered lab-on-chip to not only house this rapid assay to be later implemented into a point-of-care device, but also convert the assay from a multi-step to a one-step process. The topmost layer contains the necessary reagents and blood plasma and introduces them into the assay. The middle layer passively mixes the reagents and the plasma together via a micromixing channel and introduces them into an Archimedean clockwise spiral. At the end of this spiral, the combined reagents sink to the bottom layer into a complimentary counterclockwise spiral and ultimately exit through a side of the chip. The two spirals form the area of detection, a complete circle. Metabolic xanthine oxidase byproducts are then detected and measured.https://scholarscompass.vcu.edu/capstone/1153/thumbnail.jp

Ring Resonators with Sagnac Loops for Photonic Processing in DWDM Backbone Networks

In this paper, optical configurations based on ring resonators (RR) with an internal Sagnac (SG) loop in the feedback path, are analyzed in terms of their amplitude response and dispersive properties for filtering and chromatic dispersion managing in digital transmission systems over amplified single- mode fiber (SMF) spans in DWDM backbone networks. Design issues for the architecture as regards quadratic dispersion and magnitude distortion are provided. The RR+SG compound filter provides frequency tunability of the amplitude and dispersion peaks by adjusting a coupling coefficient of an optical coupler, with no need for using integrated thermo-optic nor current- injection based phase shifters. The configuration can be employed as an additional structure for a general RR-based design and synthesis architecture, allowing bandwidth increase of dispersion compensators and flexibility. The performance of a compound filter consisting of a two RR in series stage and a RR+SG filter are reported as a more compact and effective solution for existing multi-channel SMF backbone links operating at high bit rates. Design guidelines of an integrated ring resonator based on polymer technology for showing feasibility of the proposal is reported.This work was partially supported by Spanish CICYT (TEC2006-13273-C03-03-MIC), European project NoE EPhoton/One+, CAM (FACTOTEM-CM:S-0505/ESP/000417), FENIS-CCG06-UC3MITIC-0619.Publicad

Radio-frequency ring resonators for self-referencing fiber-optic intensity sensors

A theoretical and experimental study of radiofrequency ring resonators (RR) for referencing and improving the sensitivity of fiber-optic intensity sensors (FOS) is reported. The separation between lead and transducer losses in the FOS is solved by converting the light intensity fluctuations to be measured into RR losses that produce high amplitude variations in the proximity of the RR resonance frequencies. Two different self-referencing techniques are developed. Via the definition of the measurement parameter RM , sensor linearity and sensitivity are analyzed. A calibration using an optical attenuator is reported to validate the model.Publicad

Estrategias de comunicación transaccional para influenciar la habilidad del habla de los maestros en formación

This article is about an Action Research project carried out at a public Institution in Sincelejo, Colombia. The research purpose was to determine the effect of transactional communication strategies (TCS) on pre-service teachers’ speaking skill. In a diagnostic stage, problems in the speaking skill were identified then an action stage was carried out consisting of six workshops including TCS; a researcher journal, a student self-assessment survey, and a non-participant observation were used for data collection; results suggested a positive impact of TCS on the participants’ speaking skill represented in significant progress related to vocabulary, grammar, fluency, attitude, pronunciation, and interaction. Conclusions ratify the importance of TCS in the preparation of future Elementary School teachers in response to national bilingualism policies.Este artículo explica un proyecto de investigación acción llevado a cabo en una institución pública en Sincelejo, Colombia. El propósito de la investigación fue determinar el efecto de las estrategias de comunicación transaccional (TCS) en la habilidad del habla de los maestros en formación. En una etapa de diagnóstico, se identificaron problemas en la habilidad del habla para los que una etapa de acción de seis talleres incluyendo (TCS) se implementó; un diario de investigación, una encuesta de autoevaluación del estudiante y observación de un externo fueron usadas para la colección de datos. Los resultados sugieren un impacto positivo de TCS en el habla de los participantes representado en progresos significativo relacionado con vocabulario, gramática, fluidez, actitud, pronunciación e interacción. Las conclusiones ratifican la importancia de (TCS) en la preparación de futuros profesores de primaria en repuesta a las políticas nacionales de bilingüismo

First report on the diet of the common barn owl (<i>tyto alba</i>) from Ñeembucú Department, Paraguay

Se documentan los hábitos alimentarios de la Lechuza de Campanario (<i>Tyto alba</i>) en el sur de Paraguay, sobre la base de 35 egagrópilas recolectadas en la ciudad de Pilar, departamento Ñeembucú (26°52'S, 58°23'O). La dieta estuvo compuesta mayormente por roedores muroideos, con porcentajes menores de marsupiales, murciélagos y aves. Los sigmodontinos <i>Holochilus chacarius</i> y <i>Oligoryzomys sp</i>. representaron conjuntamente más del 59% de las presas consumidas. La amplitud de nicho trófico, estimada a partir del Índice de Levins, fue de 4.14. El promedio geométrico del peso de las presas consumidas fue de 81.24 g.We report the food habits of the Common Barn Owl (<i>Tyto alba</i>) in Pilar, Ñeembucú Department, Paraguay (26°52'S, 58°23'O). By inspecting 35 pellets we found 107 prey items. The diet consisted mainly of muroid rodents, with low frequencies of marsupials, bats, and birds. The sigmodontines <i>Holochilus chacarius</i> and <i>Oligoryzomys sp</i>. were the main prey species, accounting for more than 59% of the total prey items. Levins´s Index of food niche breadth was 4.14, and the geometric mean prey weight was 81.24 g

UN MODELO LÓGICO-FORMAL PARA EL ESTUDIO DE LOS ARGUMENTOS EMOCIONALES EN LOS PROCESOS DE CONSTRUCCIÓN DE ACUERDOS/ A LOGICAL-FORMAL MODEL FOR THE STUDY OF EMOTIONAL ARGUMENTS IN NEGOTIATION PROCESSES/ UM MODELO LÓGICO-FORMAL PARA O ESTUDO DOS ARGUMENTOS EMOCIONAIS NOS PROCESSOS DE CONSTRUÇÃO DE ACORDOS

Los argumentos son parte de un proceso comunicativo con el cual se trata de incidir en la acción de otros. Gilbert (1994) identifica cuatro modos de argumentación: el modo lógico, el modo emocional, el modo visceral y el modo kisceral. Siguiendo la línea de investigación en psicología computacional marcada por Ortony, Clore y Collins (1988) y el modelo de resolución de conflictos usando negociaciones basadas en argumentos propuesto por Jung y Tambe (2001), este trabajo presenta un modelo lógico-formal para el estudio de un modo concreto de argumentos emocionales dentro del contexto de formación de consensos enmarcado en un proceso de negociación/coordinación. Se discuten sus implicaciones en los modelos cognitivos emocionales basados en el proceso de apreciación/evaluación de la emoción

Las Fintech: Una Alternativa de Sustentabilidad en los Egocios Internacionales

En el marco de los negocios internacionales, durante los últimos años, grandes corporaciones, el sector empresarial, incluso aquellas de carácter social como las Organizaciones No Gubernamentales (ONG), fundaciones, así como integrantes de la sociedad civil con ideas de emprendimiento; han manifestado su preocupación por la conservación del medio ambiente y la reducción del impacto ambiental. Para ello, las nuevas tecnologías de información y comunicación han sido un factor clave en la consecución de estos objetivos. Es así, como las empresas Fintech, palabra que deriva de los términos finanzas y tecnología, a través del uso de plataformas digitales, han llegado a sustituir el contacto físico por medio de la automatización de procesos y servicios financieros; lo que se traduce en sinónimo de innovación, generando una influencia clave en el sector financiero sustentable. En este contexto, diversas organizaciones se han apoyado en las Fintech para delinear modelos y proyectos de negocios más sustentables, algunos de ellos, basados en las tecnologías de análisis de datos, modelos de producción y de comportamiento del consumidor; que les permitan evaluar y medir su impacto a la sustentabilidad. Es por ello, que en esta contribución se estudia cómo los negocios internacionales podrían adoptar criterios sustentables con la utilización de las nuevas tecnologías como la financiera, representada por las Fintech para el cumplimiento de sus objetivos; la inteligencia artificial para simplificar e identificar criterios de búsqueda de operaciones financieras y la tecnología blockchain que, con sus métodos innovadores de encriptación de información, fortalecen la seguridad de las transacciones financieras. &nbsp; Within the framework of international business, in recent years, large corporations, the business sector, including those of a social nature such as Non-Governmental Organizations (NGOs), foundations, as well as members of civil society with entrepreneurial ideas; They have expressed their concern for the conservation of the environment and the reduction of environmental impact. To this end, new information and communication technologies have been a key factor in achieving these objectives. This is how Fintech companies, a word that derives from the terms finance and technology, through the use of digital platforms, have come to replace physical contact through the automation of financial processes and services; which translates into synonymous with innovation, generating a key influence in the sustainable financial sector. In this context, various organizations have relied on Fintech to outline more sustainable business models and projects, some of them based on data analysis technologies, production models and consumer behavior; that allow them to evaluate and measure their impact on sustainability. That is why this contribution studies how international businesses could adopt sustainable criteria with the use of new technologies such as finance, represented by Fintech to meet their objectives; artificial intelligence to simplify and identify search criteria for financial operations and blockchain technology that, with its innovative methods of encrypting information, strengthen the security of financial transactions

Growing city farming together: A 5-year Bay Area urban agriculture & food systems needs assessment with models, barriers and recommendations to shape community engaged programming

Urban agriculture and food systems in the California Bay Area are multifaceted and intricate. There are many successful models and inspirational stories of coalition building, thousands of pounds of local food production, and overall community empowerment. Our presentation will highlight case examples, challenges, barriers, and recommendations in the University of California Cooperative Extension’s (UCCE) Urban Ag & Food Systems Program’s (UAFSP) 2019 Bay Area Needs Assessment. The needs assessment summarizes and discusses research, outreach projects and extension services the UAFSP conducted during the years 2014-2019 in five Bay Area Counties. It comprises both quantitative and qualitative information gathered from soil analysis, research, participatory research, workshop surveys, site visits and technical extension services. Projects include grant projects like USDA Beginning Farmer & Rancher Development Program workshops across California. Also, the program conducted an urban farmer’s mini-grant program with the Alameda County Resources Conservation District designed with low entry and an easy application process. The UAFSP’s projects provide a unique snapshot of urban food production systems and challenges growing in urban environments in disenfranchised communities experiencing higher levels of food insecurity and environmental injustice. One of the assessment\u27s conclusions was that land access, technical education and economic viability remain the highest challenges faced by urban agriculture and food systems groups. Most groups thrived on the social, cultural and services aspects of producing local affordable food, transforming lives, and serving important roles in their communities as food hubs, green spaces, and empowering sites. But these accomplishments were difficult to achieve due to the economic and political aspects that create an eb and flow of activity depending on grants, available resources, community, and political stakeholders. A suggested framework for supporting local food production and enhancing local food systems that presents itself is to support urban residents in becoming community food producers (AB 1990), who can not only grow local food but also safely and legally prepare and package value added products through CA Cottage Food Act (AB 1616); in the process boosting the local economy and food system by becoming a micro enterprise home kitchen operation (AB 626)

Las Fintech: una Alternativa de Sustentabilidad en los Negocios Internacionales

En el marco de los negocios internacionales, durante los últimos años, grandes corporaciones, incluidas las de carácter social, como fundaciones, ONG´s, además de empresarios y empresarias e integrantes de la sociedad civil con ideas de emprendimiento, han manifestado su preocupación por la conservación del medio ambiente y la reducción del impacto ambiental. Las organizaciones se han apoyado en las Fintech, para delinear modelos y proyectos de negocio más sostenibles, basados en las tecnologías de análisis de datos, de modelos de producción, de comportamiento del consumidor, por mencionar algunos; que le permitan evaluar y medir su impacto a la sustentabilidad. Las empresas Fintech se traducen en sinónimos de innovación, y hoy más que día su influencia es clave en el sector financiero sustentable. En esta contribución se revisa la importancia de que en los negocios internacionales se adopten los criterios de sustentabilidad, con la utilización de las nuevas tecnologías; como la financiera, representada por las Fintech para el cumplimiento de sus objetivos. &nbsp; Within the framework of international business, in recent years, large corporations, including those of a social nature, such as foundations, NGOs, as well as businessmen and women and members of civil society with entrepreneurial ideas, have expressed their concern about the conservation of the environment and the reduction of the environmental impact. Organizations have relied on Fintech to outline more sustainable business models and projects, based on data analysis technologies, production models, consumer behavior, to name a few; that allow it to evaluate and measure its impact on sustainability. Fintech companies are synonymous with innovation, and today more than ever their influence is key in the sustainable financial sector. This contribution reviews the importance of international business adopting sustainability criteria, with the use of new technologies; as the financial, represented by the Fintech for the fulfillment of its objectives