An integrated framework for learning analytics

Low retention rates have been an ongoing concern, especially among educational institutions amidst expanding their student base and catering to large and diverse student cohorts. Increasing retention rates without lowering academic standards poses many challenges. The traditional teaching techniques using a one-size-fits-all approach appear to be less effective, and the size and diversity of cohorts demand innovative teaching techniques allowing for adaptive and personalized coaching and learning. In this thesis, we propose a novel, adaptive and integrated analytics framework for learning analytics to address the key concerns of educational institutions. The proposed framework comprises three layers: (1) the conceptual layer which is a context-agnostic and generic analytics layer including descriptive, predictive, and prescriptive techniques; (2) the logical layer or the context-specific learning analytics processes layer that specializes the conceptual layer in the context of education; ten key learning analytics processes are formalized, implemented, and linked to the conceptual layer components; finally, (3) the physical layer that is concerned with education-oriented application implementations and is a context-specific components/algorithmic implementation of the logical layer processes. Our proposed framework, however, is not limited only to the learning and teaching environment. As a proof of concept, we chose the education context and applied our framework on it. The three-layered integrated learning analytics framework proposed allows domain-agnostic elements defined in the conceptual layer to be realized by domain-specific processes in the logical layer, and implemented through existing and new components in the physical layer. Please note that the learning analytics is not confined to the education context alone. The framework, therefore, can be customized for different domains making the approach more widely applicable. An adaptive and innovative approach in the physical layer named the personalized prescriptive quiz (PPQ) is introduced as a demonstration of education-oriented applications assisting the educational institutions. The novel agile learning approach proposed combines descriptive, predictive and prescriptive analytics to create a personalized iterative and incremental approach to learning. The PPQ allows students to easily analyze their current problems (especially, identifying their misconceptions), predict future results, and benefit from personalized intervention tasks. The enhanced PPQ incorporating difficulty and discrimination indexes, run-time question selection, and a hybrid iterative predictive model can be more beneficial and effective for personalized learning. The results demonstrate a significant improvement in student academic performance after applying the PPQ approach. In addition, students claimed that the PPQ helped them elevate their self-esteem and improve student experience which may eventually lead to improved retention rates

Guideline for Optical Optimization of Planar Perovskite Solar Cells

Organometallic halide perovskite solar cells have emerged as a versatile photovoltaic technology with soaring efficiencies. Planar configuration in particular, has been a structure of choice thanks to its lower temperature processing, compatibility with tandem solar cells and potential in commercialization. Despite all the breakthroughs in the field, the optical mechanisms leading to highly efficient perovskite solar cells lack profound insight. In this paper, a comprehensive guideline is introduced involving semi-analytical equations for thickness optimization of the front and rear transport layers, perovskite, and transparent conductive oxides to improve the antireflection and light trapping properties, and therefore to maximize the photocurrent of perovskite solar cells. It is shown that a photocurrent enhancement above 2 mA/cm2 can be achieved by altering - reducing or increasing - the thicknesses of the layers constituting a CH3NH3PbI3 (MAPI) type perovskite solar cell. The proposed guideline is tested against experiments as well as previously published experimental and simulation results for MAPI. Additionally, the provided guideline for various types of perovskites can be extended to other direct band gap absorber-based solar cells in superstrate configuration

Preparation and Characterization of Mixed Halide MAPbI3−xClx Perovskite Thin Films by Three‐Source Vacuum Deposition

Chloride has been extensively used in the preparation of metal halide perovskites such as methylammonium lead iodide (MAPbI3-xClx), but its persistence and role in solution-processed materials has not yet been rationalized. Multiple-source vacuum deposition of perovskites enables a fine control over the thin-film stoichiometry, and allows to incorporate chemical species irrespectively of their solubility. In this communication, we present the first example of mixed MAPbI3-xClx thin films prepared by three-source vacuum deposition using MAI, PbI2 and PbCl2 as precursors. The optoelectronic properties of the material are evaluated through photovoltaic and electro-/photo-luminescent characterizations. Besides the very similar structural and optical properties of MAPbI3 and MAPbI3-xClx, we observed an increased electroluminescence efficiency, longer photoluminescence lifetimes, as well as larger photovoltage in the presence of chloride, suggesting a reduction of the non-radiative charge recombination

Anesthetic Considerations in a Patient With Plexiform Neurofibromatosis: A Case Report

Plexiform neurofibromatosis is an uncommon variant of neurofibromatosis type 1 (NF1) (Von Recklinghausen’s disease). There is a greater prevalence of neurofibromatosis 1 in patients with other neoplasms, such as rhabdomyosarcomas, gastrointestinal stromal tumors (GISTs), pheochromocytomas, carcinoid tumors and ganglioneuromas. We report the anesthetic implications of a case of a 33 year old patient with plexiform neurofibromatosis and a history of pheochromocytoma which was operated on previously. He presented with painless swelling on upper eye-lead since childhood and had multiple café-au-lait spots and neurofibromas on the trunk. The surgery was done in two sessions first on the plexiform neurofibroma of the eye followed by the operation on the brain mass

Anesthetic considerations in a patient with Psoriasis undergoing CABG surgery

A 51 years old man with a 30 years history of psoriasis was scheduled for elective CABG due to 3 vessels coronary artery involvement and the resulting ischemic heart diseases. The psoriatic lesions were on the limbs and posterior parts of the trunk. The perioperative period was eventless and the patient was under care in postoperative cardiac ICU ward. He was discharged home 10 days after the operation with stable psoriasis state

Efficient and Stable Inverted Wide-Bandgap Perovskite Solar Cells and Modules Enabled by Hybrid Evaporation-Solution Method

Wide-bandgap perovskite solar cells (WBG-PSCs), when partnered with Si bottom cells in tandem configuration, can provide efficiencies up to 44%; yet, the development of stable, efficient, and scalable WBG-PSCs is required. Here, the utility of the hybrid evaporation-solution method (HESM) is investigated to meet these demanding requirements via its unique advantages including ease of control and reproducibility. A PbI2/CsBr layer is co-evaporated followed by coating of organic-halide solutions in a green solvent. Bandgaps between 1.55–1.67 eV are systematically screened by varying CsBr and MABr content. Champion efficiencies of 21.06% and 20.35% in cells and 19.83% and 18.73% in mini-modules (16 cm2) for perovskites with 1.64 and 1.67 eV bandgaps are achieved, respectively. Additionally, 18.51%-efficient semi-transparent WBG-PSCs are implemented in 4T perovskite/bifacial silicon configuration, reaching a projected power output of 30.61 mW cm−2 based on PD IEC TS 60904-1-2 (BiFi200) protocol. Despite similar bandgaps achieved by incorporating Br via MABr solution and/or CsBr evaporation, PSCs having a perovskite layer without MABr addition show significantly higher thermal and moisture stability. This study proves scalable, high-performance, and stable WBG-PSCs are enabled by HESM, hence their use in tandems and in emerging applications such as indoor photovoltaics are now within reach.</p

Tin(IV) Oxide Electron Transport Layer via Industrial-Scale Pulsed Laser Deposition for Planar Perovskite Solar Cells

Electron transport layers (ETL) based on tin(IV) oxide (SnO2) are recurrently employed in perovskite solar cells (PSCs) by many deposition techniques. Pulsed laser deposition (PLD) offers a few advantages for the fabrication of such layers, such as being compatible with large scale, patternable, and allowing deposition at fast rates. However, a precise understanding of how the deposition parameters can affect the SnO2 film, and as a consequence the solar cell performance, is needed. Herein, we use a PLD tool equipped with a droplet trap to minimize the number of excess particles (originated from debris) reaching the substrate, and we show how to control the PLD chamber pressure to obtain surfaces with very low roughness and how the concentration of oxygen in the background gas can affect the number of oxygen vacancies in the film. Using optimized deposition conditions, we obtained solar cells in the n¿i¿p configuration employing methylammonium lead iodide perovskite as the absorber layer with power conversion efficiencies exceeding 18% and identical performance to devices having the more typical atomic layer deposited SnO2 ETL