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Publications

2018

Participants' experience in the music festival Rock in Rio Lisboa [Experiência dos participantes no festival de música Rock in Rio Lisboa]

Authors
Queirós, F; Barbosa, B;

Publication
Espacios

Abstract
This research aims to contribute to the understanding of how the experience influences music festival participants' satisfaction, and the latter affects future behavior. A quantitative methodology was adopted using a questionnaire as research instrument, which was applied to 240 participants in the Rock in Rio Lisbon festival 2014. The results point to a positive relation between satisfaction and the different dimensions of experience, including the social one that was developed for the present study. © 2018. revistaESPACIOS.com.

2018

Expression Atlas: gene and protein expression across multiple studies and organisms

Authors
Papatheodorou, I; Fonseca, NA; Keays, M; Tang, YA; Barrera, E; Bazant, W; Burke, M; Füllgrabe, A; Pomer Fuentes, AM; George, N; Huerta, L; Koskinen, S; Mohammed, S; Geniza, MJ; Preece, J; Jaiswal, P; Jarnuczak, A; Huber, W; Stegle, O; Vizcaíno, JA; Brazma, A; Petryszak, R;

Publication
Nucleic Acids Research

Abstract
Expression Atlas (http://www.ebi.ac.uk/gxa) is an added value database that provides information about gene and protein expression in different species and contexts, such as tissue, developmental stage, disease or cell type. The available public and controlled access data sets from different sources are curated and re-analysed using standardized, open source pipelines and made available for queries, download and visualization. As of August 2017, Expression Atlas holds data from 3,126 studies across 33 different species, including 731 from plants. Data from large-scale RNA sequencing studies including Blueprint, PCAWG, ENCODE, GTEx and HipSci can be visualized next to each other. In Expression Atlas, users can query genes or gene-sets of interest and explore their expression across or within species, tissues, developmental stages in a constitutive or differential context, representing the effects of diseases, conditions or experimental interventions. All processed data matrices are available for direct download in tab-delimited format or as R-data. In addition to the web interface, data sets can now be searched and downloaded through the Expression Atlas R package. Novel features and visualizations include the on-the-fly analysis of gene set overlaps and the option to view gene co-expression in experiments investigating constitutive gene expression across tissues or other conditions. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

2018

Languages and models for hybrid automata: A coalgebraic perspective

Authors
Neves, R; Barbosa, LS;

Publication
THEORETICAL COMPUTER SCIENCE

Abstract
We study hybrid automata from a coalgebraic point of view. We show that such a perspective supports a generic theory of hybrid automata with a rich palette of definitions and results. This includes, among other things, notions of bisimulation and behaviour, state minimisation techniques, and regular expression languages.

2018

System protection agent against unauthorized activities via USB devices

Authors
Oliveira, J; Frade, M; Pinto, P;

Publication
IoTBDS 2018 - Proceedings of the 3rd International Conference on Internet of Things, Big Data and Security

Abstract
Security attacks using USB interfaces and devices are becoming more advanced, which boost efforts to develop counter measures in order to protect systems and data. One of the most recent attacks using USB devices is the BadUSB attack, performed by spoofing the device’s firmware and allowing the attackers to execute a set of malicious actions, e.g. an USB storage device could be mounted as USB keyboard in order to inject malicious scripts into the system. This paper proposes a protection agent against BadUSB attack developed for Windows operative systems. It allows a user to check the class of an USB device ready to be mounted, though enabling the detection of a potential attack if the expected functionality of the device does not match with its class type. The results show that the proposed protection agent is capable of detecting potential intrusions by blocking the installation of the device, scanning the device for something that identifies it, searching for a description locally and finally warning the user about the device meaning that all devices must be approved by the user when plugged in if the system protection agent is running. Copyright

2018

Superfluidity of light in nematic liquid crystals

Authors
Ferreira, TD; Silva, NA; Guerreiro, A;

Publication
PHYSICAL REVIEW A

Abstract
Optical analog experiments have captured a lot of interest in recent years by offering a strategy to test theoretical models and concepts that would be otherwise untestable. The approach relies on the similarity between the mathematical model for light propagation in nonlinear optical media and the model to be mimicked. In particular, the analogy between light and a quantum fluid with superfluidlike properties has been studied extensively. Still, while most of these studies use thermo-optical media to perform these experiments, the possibility of using nematic liquid crystals to perform such optical analog experiments remains to be analyzed. This work explores how this medium can constitute an alternative to materials more commonly used in optical analogs, such as thermo-optical media, and how its tunable properties can be advantageous to explore and better control fluidlike properties of light. Moreover, we explore the analogy between the propagation of light and a quantum fluid, and propose a pump-probe experiment to measure the dispersion relation of the superfluid analog.

2018

Causality assessment of adverse drug reaction reports using an expert-defined Bayesian network

Authors
Rodrigues, PP; Ferreira Santos, D; Silva, A; Polonia, J; Ribeiro Vaza, I;

Publication
ARTIFICIAL INTELLIGENCE IN MEDICINE

Abstract
In pharmacovigilance, reported cases are considered suspected adverse drug reactions (ADR). Health authorities have thus adopted structured causality assessment methods, allowing the evaluation of the likelihood that a drug was the causal agent of an adverse reaction. The aim of this work was to develop and validate a new causality assessment support system used in a regional pharmacovigilance centre. A Bayesian network was developed, for which the structure was defined by experts while the parameters were learnt from 593 completely filled ADR reports evaluated by the Portuguese Northern Pharmacovigilance Centre medical expert between 2000 and 2012. Precision, recall and time to causality assessment (TTA) was evaluated, according to the WHO causality assessment guidelines, in a retrospective cohort of 466 reports (April-September 2014) and a prospective cohort of 1041 reports (January-December 2015). Additionally, a simplified assessment matrix was derived from the model, enabling its preliminary direct use by notifiers. Results show that the network was able to easily identify the higher levels of causality (recall above 80%), although struggling to assess reports with a lower level of causality. Nonetheless, the median (Q1:Q3) ITA was 4 (2:8) days using the network and 8 (5:14) days using global introspection, meaning the network allowed a faster time to assessment, which has a procedural deadline of 30 days, improving daily activities in the centre. The matrix expressed similar validity, allowing an immediate feedback to the notifiers, which may result in better future engagement of patients and health professionals in the pharmacovigilance system.

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