Abstract
O recurso à modelação como metodologia de ensino é relevante no processo de recriação e simulação de fenómenos naturais, nomeadamente fenómenos geológicos e ambientais. Pretendendo-se verificar se o recurso à modelação é uma metodologia significativa no sucesso da aprendizagem dos estudantes de riscos naturais do ensino superior português, foram analisadas as fichas das unidades curriculares que abordam temáticas de riscos naturais nas universidades públicas portuguesas, tendo-se optado por selecionar apenas unidades curriculares do primeiro ciclo de estudos – licenciatura. No total foram analisadas, com recurso a uma grade de análise, oito fichas de unidades curriculares, ministradas em sete universidades públicas portuguesas. Asevidências encontradas indicam que nenhum dos documentos em análise contempla a utilização da modelação como metodologia de ensino de temáticas de riscos naturais, predominando um ensino essencialmente tradicional, sobressaindo a necessidade de intervenção ao nível das metodologias de ensino valorizando-se a manipulação e a exploração de modelos no ensino superior.

Abstract
Suicide is a serious public health problem and is among the top ten causes of death worldwide for all age groups. It is the third leading cause among 15-35-year olds. The main objective of this quasi-experimental, quantitative, and cross-sectional study was to compare the levels of suicidal ideation among college students (n = 50) and nonstudents (n = 51). Subjects were compared according to sex, age, place of residence, living arrangements, educational level, and occupational status using the Suicidal Ideation Questionnaire. The sample consisted of 101 individuals aged 18- 25 years, Mean of 21.44 years and Standard Deviation of 2.43. The results showed higher levels of suicidal ideation among the non-college students. Statistically significant effects were found among the following variables: level of education, occupational status, living alone, and presence of anxiety disorder and/or depression. The findings of this study suggest the need for suicide prevention measures in order to reduce deaths by suicide and suicide attempt rate.

Abstract

Abstract
This paper presents the analysis of switching-current (SC) and switching-resistance (SR) modes of operation in digital power amplifiers (DPAs). Large output power back-off (PBO) generally shifts the DPA from SR to SC operation. Hence, an analytical study is performed to characterize these regimes. A current-mode class-D architecture has been used to implement a DPA in which both operation conditions were examined. Two mechanisms were addressed to study the AM-AM performance of the DPA, namely the knee voltage and the output resistance of the transistor. To evaluate the impact of these parameters in the AM-AM profile, we proposed a simplified transistor model in which both parameters can be defined independently without affecting each other. This allowed us to isolate and determine the effects in the AM-AM distortion, helping to conclude that the output resistance turns out to be the most dominant parameter. The study has been validated using simulations in Spectre RF with three different CMOS process nodes (130, 65, and 45nm).

Abstract
High-maturity software development processes, such as the Team Software Process and the accompanying Personal Software Process (PSP), can generate significant amounts of data that can be periodically analyzed to identify performance problems, determine their root causes, and devise improvement actions. However, there is a lack of tool support for automating that type of analysis, and hence diminish the manual effort and expert knowledge required. So, we propose in this paper a comprehensive performance model, addressing time estimation accuracy, quality, and productivity, to enable the automated (tool based) analysis of performance data produced by PSP developers, namely, identify and rank performance problems and their root causes. A PSP data set referring to more than 30000 projects was used to validate and calibrate the model. Copyright (c) 2015 John Wiley & Sons, Ltd.

Abstract
Technology for virtual reality has evolved at a fast pace and so is its affordability. Equipment such as head-mounted displays are now available for the average consumer at reasonable prices and this potentiates the use of contents such as video 360 in a more natural way. The purpose of this study was to measure the sense of presence and cybersickness comparing subjects by gender while experiencing a virtual reality application composed by type of VIDEO (360 video and 3D 360 video) using an head-mounted display. A Portuguese version of the Igroup Presence Questionnaire (IPQ) was used together with the Simulator Sickness Questionnaire (SSQ). The results have revealed that there are no significant differences across 2D and 3D videos in the sense of presence or cybersickness. © 2016 ACM.