Análisis CAQDAS aplicado a textos discentes en ciencias sociales. Posibilidades y limitaciones

The teaching analysis of content in Social Sciences faces the huge amount of texts generated by students during their learning (summaries, exams, essays, works...). Digital tools have so far not had a clear effect of teacher attendance, but we understand that this may change. We present a case study in which the CAQDAS methodology is applied to 14 undergraduate students, who worked on the concept of democracy. This results in 75 freely labeled text comments analyzed by Atlas.ti. The methodology used allowed to work effectively the multiplicity of labels, to establish a modal category system, as well as to analyze the quality and coherence of the contents. The results are considered satisfactory and demonstrate that it is possible to analyse a data set efficiently and transparently, with the support of such a methodology. This opens the door to new experiences in denser contexts.El análisis docente de contenidos en Ciencias Sociales se enfrenta a la ingente cantidad de textos que genera el alumnado durante su aprendizaje (resúmenes, exámenes, ensayos, trabajos…). Las herramientas digitales no han tenido hasta ahora un efecto claro de asistencia docente, pero entendemos que esto puede cambiar. Presentamos un estudio de caso en el que se aplica la metodología CAQDAS sobre 14 estudiantes de grado, que trabajaron el concepto de democracia. Se obtiene así 75 comentarios de texto, de etiquetado libre, analizados mediante Atlas.ti. La metodología utilizada permitió trabajar de forma eficaz la multiplicidad de etiquetas, para establecer un sistema de categorías modal, así como analizar la calidad y coherencia de los contenidos. Los resultados se consideran satisfactorios y demuestran que es posible analizar un conjunto de datos de forma eficiente y transparente, con el apoyo de dicha metodología. Lo que abre las puertas a experiencias en contextos más densos

Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting

Energy efficiency and consumers' role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers' power converters track the power setpoints obtained from the proposed strategy.Spanish Agencia Estatal de Investigacion ; Fondo Europeo de Desarrollo Regional

Energy management strategy to coordinate batteries and ultracapacitors of a hybrid energy storage system in a residential prosumer installation

Publicado en 2017 International Young Engineers Forum (YEF-ECE), Almada (Portugal), pp. 30-35, doi: 10.1109/YEF-ECE.2017.7935636En los últimos años, los sistemas de energía han experimentado un gran desarrollo como consecuencia de la aparición de la generación distribuida. Las fuentes de energía renovables, los usuarios activos y los vehículos eléctricos juegan un papel fundamental en los sistemas de energía, lo que supone un nuevo tema de investigación. En este escenario, la figura del prosumidor ha ganado relevancia debido a las múltiples ventajas que pueden aportar para mejorar el comportamiento de los sistemas de energía y lograr ahorros de energía y costos. En particular, se presta especial atención a los conjuntos fotovoltaicos (PV) integrados en edificios residenciales con sistemas de almacenamiento de energía (ESS), como baterías o ultracondensadores (UC) o incluso una combinación de ambos en un sistema de almacenamiento de energía híbrido (HESS). Este artículo presenta una estrategia de gestión de energía para intercambiar energía entre las baterías y las UC que forman un HESS instalado con una matriz FV en una vivienda de prosumidores para mantener su banco de UC disponible para satisfacer los requisitos de energía durante el mayor tiempo posible.In recent years, power systems have experimented a great development as a consequence of the apparition of the distributed generation. Renewable energy sources, active users and electric vehicles play a fundamental role in power systems, which has supposed a new topic research. In this scenario, the figure of prosumer has gained relevance due to the multiple advantages that they can contribute to improve the behavior of power systems and to achieve energy and cost savings. In particular, special attention is focus on photovoltaic (PV) arrays integrated in residential buildings with energy storage systems (ESSs), such as batteries or ultracapacitors (UCs) or even a combination of both in a hybrid energy storage system (HESS). This paper presents an energy management strategy to Exchange energy between the batteries and the UCs that form a HESS installed with a PV array in a prosumer dwell in order to maintain its UC bank available to support the energy requirements during the most time possible

Comprehensive study of the benefits of integrating a sharing energy strategy between prosumers

Publicado en IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society, Beijing, 2017, pp. 3609-3614, doi: 10.1109/IECON.2017.8216612La actualización de los sistemas de energía en los últimos años debido a la proliferación de la generación distribuida con fuentes de energía renovables, usuarios activos y vehículos eléctricos se ha convertido en un desafío. En este nuevo escenario, los prosumidores juegan un papel importante para amortiguar la curva de consumo y, por lo tanto, contribuir a los requisitos de la red. Los conjuntos fotovoltaicos (PV) integrados en edificios residenciales atraen una atención especial, ya que pueden complementarse con sistemas de almacenamiento de energía (ESS), como baterías o ultracondensadores (UC) o incluso una combinación de ambos, con el objetivo de lograr que los clientes puedan administrar su energía. Las razones anteriores justifican la necesidad de un sistema de gestión de energía (EMS) que coordine el funcionamiento de los dispositivos de almacenamiento de energía de manera optimizada, ya que son caros. En este documento, se propone un sistema de control integral para intercambiar energía entre los dispositivos de almacenamiento híbridos (baterías y UC) de dos viviendas con instalaciones fotovoltaicas con el fin de aumentar la disponibilidad de sus ESS y soportar los requisitos de energía durante el mayor tiempo posible, optimizando tamaños y costos, y evitando la saturación.The upgrade of power systems in the last years due to the proliferation of distributed generation with renewable energy sources, active users and electric vehicles has become a challenge. In this new scenario, prosumers play an important role in order to buffer the consumption curve and, therefore, contributing to the grid requirements. Special attention is attracted by photovoltaic (PV) arrays integrated in residential buildings, because they can be complemented with energy storage systems (ESSs), such as batteries or ultracapacitors (UCs) or even a combination of both, with the aim to achieve that customers could manage their energy. The above reasons justify the need of an energy management system (EMS) that coordinates the operation of the energy storage devices in an optimized way, as they are expensive. In this paper, a comprehensive control system is proposed to exchange energy between the hybrid storage devices (batteries and UCs) of two dwells with PV installations in order to increase the availability of their ESSs and support the energy requirements during the most time possible, optimizing sizes and costs and avoiding saturation.peerReviewe

ESPACE ET TEMPS DANS LES CAMPUS VIRTUELS: DOMAINE DE RECHERCHE EN DIDACTIQUE DE LA GÉOGRAPHIE

El presente artículo pretende abrir ámbitos y estrategias de investigación en Didáctica de la Geografía y las Ciencias Sociales, con objeto de crear nuevos puentes entre las tradiciones científica y educativa de la disciplina. Se plantea el uso de los Campus Virtuales como fuente de datos, y metadatos, de interés para el estudio del proceso de enseñanza, así como para su rendimiento académico. A tal objeto, se realiza un estudio de caso a partir de 70 133 eventos generados por 398 alumnos de grado en 6 asignaturas durante el curso académico 2018/19. La metodología utilizada es fundamentalmente cuantitativa, centrada en técnicas propias de la estadística exploratoria, la minería de datos y Big Data. El análisis realizado ha permitido comprobar las posibilidades de la información generada por los discentes en su interacción con las plataformas de aprendizaje, así como detectar algunas singularidades de interés, entre las que destacan las diferencias en la movilidad, y la interacción con aquella, entre hombres y mujeres. Consideramos, así, que se está ante un espacio de encuentro científico-educativo de interés para la comunidad geográfica, sobre el que merecería la pena seguir explorando para superar las limitaciones de estudios de caso como el presente

Low-Dose PET/CT and Full-Dose Contrast-Enhanced CT at the Initial Staging of Localized Diffuse Large B-Cell Lymphomas

Computed tomography (CT) has been used as the reference imaging technique for the initial staging of diffuse large B-cell lymphoma until recent days, when the introduction of positron emission tomography (PET)/CT imaging as a hybrid technique has become of routine use. However, the performance of both examinations is still common. The aim of this work was to compare the findings between low-dose 2-deoxy-2-(F-18) fluoro-D-glucose (F-18-FDG) PET/CT and full-dose contrast-enhanced CT (ceCT) in 28 patients with localized diffuse large B-cell lymphoma according to PET/CT findings, in order to avoid the performance of ceCT. For each technique, a comparison in the number of nodal and extranodal involved regions was performed. PET/CT showed more lesions than ceCT in both nodal (41 vs. 36) and extranodal localizations (16 vs. 15). Disease staging according to both techniques was concordant in 22 patients (79%) and discordant in 6 patients (21%), changing treatment management in 3 patients (11%). PET/CT determined a better staging and therapeutic approach, making the performance of an additional ceCT unnecessary

Comparison of different automatic methods for the delineation of the total metabolic tumor volume in I-II stage Hodgkin Lymphoma

Total metabolic tumor volume (TMTV) is a promising quantitative biomarker for therapy assessment and prognosis in Hodgkin Lymphoma affected patients that allows prediction of patient outcome. The aim of this study was to evaluate the TMTV reproducibility between different sources of variability in tumor delimitation such as SUV-based thresholds (2.5, 41% and 50%) and software tools (Beth Israel plugin (BI) and LIFEx). Effect of contouring procedure both including single and multiple regions of interest was also studied in patients with multiple lesions, and optimal cut-offs for each studied method were displayed to compare the effect on prognosis. Strong alikeness in TMTV was found for 2.5 under software choice. Best accuracy in contouring compared to visual assessment of the disease was found for BI multiple ROI and LIFEx single ROI drawing. Similar cut-offs were found between both software for all considered thresholds, but best resemblance and highest cut-off due to an overestimation of the TMTV was found for 2.5 SUV. Our findings suggest that optimal reproducibility in TMTV is found for SUV>2.5 threshold under choice of contouring methodology or software tool, meaning that overestimation of the TMTV threshold using 2.5 looks to be preferable than underestimation with 41% and 50%

SPECT-CT metabolic and morphological study of 2 types of cemented hip stem prostheses in primary total hip arthroplasty patients

Background: Cemented hip arthroplasty requires applying a layer of polymethylmethacrylate (cement) in the space between the bone and the prosthetic stem. This can be achieved using 2 techniques: the thick-layer technique (requires a layer of at least 2 mm to surround an undersized prosthetic stem), and the thin-layer technique (requires a thin layer of cement, so that the prosthetic stem fills the femoral medullary canal). Both approaches have excellent long-term clinical and radiological outcomes, although an implant's insertion into the bone generates inevitable bone mass and bone metabolic changes around it. Combination of single photon emission computed tomography and computed tomography scan (SPECT-CT) imaging combines the single photon emission computed tomography's ability to provide detailed bone metabolism assessment with the computed tomography scan's capacity to provide a meticulous anatomical study. Methods: This is a single center, open label, randomized clinical trial, performed in the premises of the Bellvitge University Hospital. Participants will be randomly assigned to the Thick-layer technique group (Exeter V40 Cemented Femoral Stem) or to the French paradox technique group (Müller Straight Stem). All participants will have a SPECT-CT scan study at 3, 6, 12, and 24 months after the surgery. Discussion: Surgical distress itself and the implant's insertion into the bone may cause microvascular changes that alter periprosthetic bone mass and bone metabolism. To the best of our knowledge, there are no studies using SPECT-CT to compare bone metabolism evolution in the postoperative period between these 2 surgical cementation techniques. We aim to provide information in this regard that could help decision making in complicated implant cases and, maybe, pave the way for larger, and methodologically improved studies

Usefulness of 18F-FDG PET-CT for assessing large-vessel involvement in patients with suspected giant cell arteritis and negative temporal artery biopsy

Objective: To investigate the usefulness of F-18-FDG PET-CT for assessing large-vessel (LV) involvement in patients with suspected giant cell arteritis (GCA) and a negative temporal artery biopsy (TAB).Methods: A retrospective review of our hospital databases was conducted to identify patients with suspected GCA and negative TAB who underwent an F-18-FDG PET-CT in an attempt to confirm the diagnosis. The gold standard for GCA diagnosis was clinical confirmation after a follow-up period of at least 12 months.Results: Out of the 127 patients included in the study, 73 were diagnosed with GCA after a detailed review of their medical records. Of the 73 patients finally diagnosed with GCA, F-18-FDG PET-CT was considered positive in 61 cases (83.5%). Among the 54 patients without GCA, F-18-FDG PET-CT was considered positive in only eight cases (14.8%), which included 1 case of Erdheim-Chester disease, 3 cases of IgG4-related disease, 1 case of sarcoidosis, and 3 cases of isolated aortitis. Overall, the diagnostic performance of F-18-FDG PET-CT for assessing LV involvement in patients finally diagnosed with GCA and negative TAB yielded a sensitivity of 83.5%, specificity of 85.1%, and a diagnostic accuracy of 84% with an area under the ROC curve of 0.844 (95% CI: 0.752 to 0.936). The sensitivity was 89% in occult systemic GCA and 100% in extracranial LV-GCA.Conclusion: Our study confirms the utility of F-18-FDG PET-CT in patients presenting with suspected GCA and a negative TAB by demonstrating the presence of LV involvement across different subsets of the disease

Geografía y pensamiento geográfico en educación superior: una luz que se extingue, una razón para actuar.

Reflexión sobre la situación académica y la proyección educativa y social a medio plazo.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech