In today's knowledge society, knowing how to interpret, search, communicate and share new information are key skills for a successful citizen. Such skills, known as 21st century skills, include critical thinking, teamwork, communication, among others. Currently, there are several proposals on how to integrate the learning of these skills in basic education, including through the teaching of computing. Yet, based on the hypothesis that teaching computing can contribute to the learning of 21st century skills, there is few systematically evidence available to support this claim. One reason for this absence is the lack of 21st century skills assessment models. Thus, the objective of this article is to develop and evaluate a model for the assessment of 21st century skills in the context of teaching computing in basic education. Based on the results of a mapping study, the bASES21 model is systematically developed as well as its measurement instrument, a self-assessment questionnaire. An initial assessment in terms of reliability and validity of the measurement instrument, based on 148 responses from students in basic education, indicate a high internal reliability (Cronbach's alpha = 0.958). Results regarding the validity of the instrument were inconclusive. Even although some skills demonstrate internal correlation, an improvement opportunity is the possible re-classification of items based on a more detailed analysis with a larger sample. Thus, the bASES21 model represents a first step supporting the assessment of 21st century skills, aiming at the systematic improvement of teaching computing in basic education.
An AC-AC converter with a high-frequency link employing an LLC resonant converter operating in the vicinity of the resonance frequency was studied, in which a single output power stage is used, formed by a high-frequency AC-AC converter employing four-quadrant switches. The topology, its operation and the modulation strategy are described. The high-frequency stage switches located on the primary side of the transformer operate with soft switching of the ZVS type, while the four-quadrant switches that form the output stage operate with soft switching of the ZCS type. Experimental data obtained with a 1.5 kW experimental prototype (input 220 VRMS, output 220 VRMS and switching frequency 40 kHz), which was designed, built and tested in the laboratory, are reported herein. This converter can be considered a candidate for the building block of medium voltage solid-state transformers (SST) for power distribution systems.
Behçet's disease is a multisystemic disease consisting of a varying combination of ocular, mucocutaneous, neurologic, cardiovascular, gastrointestinal and other manifestations. Its diagnosis is based on clinical criteria, in which a positive pathergy test scores 1. A case series with 26 suspected patients is presented, and the skin pathergy test was performed in 23. The results were read in 48hours, and they were considered negative when without papule, and positive with a papule or pustule. Positive results were divided by papule size, and dermatoscopy was done to measure and observe its clinical aspects. After the readings, a biopsy was performed, with annotation of histopathological aspects. The test was negative in 2 (8.7%) and positive in 21 (91.3%) patients. The results and the literature review are presented.
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