Postolache O.A.,Telecommunications Institute of Portugal |
Girao P.M.B.S.,Telecommunications Institute of Portugal |
Girao P.M.B.S.,University of Lisbon |
Mendes J.,University of Porto |
And 3 more authors.
IEEE Transactions on Instrumentation and Measurement | Year: 2010
This paper presents a multisensing system with wireless communication capabilities embedded on a smart wheelchair that can measure physiological parameters such as heart rate and respiratory rate in an unobtrusive way. Ballistocardiography (BCG) sensors and a three-axis inertial microelectromechanical system accelerometer are embedded on the seat or in the backrest of the wheelchair and the acquired data are transmitted by Wi-Fi to a laptop computer for advanced data processing and logging. In addition, a 3-D accelerometer with ZigBee communication capability is used to extract information about the user's posture. Considering the static and dynamic use of the wheelchair, an extended set of measurements for different utilization scenarios was analyzed. An important part of this paper is focused on BCG noise and artifacts removal and heart rate and respiratory rate accurate estimation from BCG signal using wavelet-based filtering and independent component analysis algorithms. A study on wavelet-based filtering considering different types of mother wavelets and different levels of decomposition was also carried out. In the future, other signals will also be acquired to improve the system capabilities and flexibility. © 2010 IEEE.
Pires D.F.,University of Lisbon |
Pires A.M.,University of Lisbon |
Pires A.M.,Atlantic University |
Collares-Pereira M.J.,University of Lisbon |
Magalhaes M.F.,University of Lisbon
Ecology of Freshwater Fish | Year: 2010
Knowledge of patterns of refuge use by fish is critical for maintaining biodiversity in drought-prone streams. In this study, the fish assemblages of 21 dry-season pools in a Mediterranean stream were characterised and related to three sets of factors reflecting pool morphology, physicochemistry and spatial context. Fish were associated with the three sets of variables, with variation partitioning indicating that overall species richness and abundance were primarily related to pool morphology but relative species abundances were mainly associated with physicochemical contexts. In general, species richness was the highest but overall fish abundance was the lowest in large pools. Pools well shaded by riparian canopy held the highest richness and abundance of native fish, but relative species abundances and assembly structure varied among pools contingent on canopy cover, substrate composition and spatial location. These results suggested that conservation of fish diversity in Mediterranean streams requires networks of pools with diverse sizes and physicochemical contexts. © 2009 John Wiley & Sons A/S.
Postolache G.,Atlantic University
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011
In this paper Heart Rate Variability (HRV) and Blood Pressure Variability (BPV) were analyzed before the onset of cardiac arrhythmia in order to derive markers for short-term forecasting. The (a) coherence between systolic blood pressure (SBP) and cardiac oscillations in low-frequency (LF) and high-frequency (HF) band; (b) fluctuations of phase; (c) HRV and BPV as a LF power and HF power in frequency and time-frequency domain; (d) transfer function analysis of cardiovascular signals were analyzed. Arrhythmia was preceded by: a) lower coherence; b) increase in fluctuations of phase between signals; c) higher spectral energy associated with respiratory frequency in blood pressure signal; d) raise of sympathetic outflow to the heart; e) decreased HRV. Cardiac arrhythmia was characterized mainly by an increase in LF power of blood pressure, cardiac signal and transfer function. During self-termination of arrhythmia a larger increased in total BPV and HRV was recorded. These results suggest that important information about both neuronal cardiovascular control and risk for spontaneous arrhythmia can be provided by combined analysis of frequency, phase, and time-frequency analysis of blood pressure and cardiac oscillation.
Alves A.M.,Atlantic University
TripleC | Year: 2014
Jacques Ellul's thoughts on the increasingly conspicuous role of persuasion techniques bring to the fore the persuasive and normative effects of new communication techniques at the core of contemporary consumer/citizen culture, as well as the limits of that instrumental stance towards mediated human communication. By drawing insights from authors who shared some of Ellul's concerns, such as Frankfurt School theorists, Vance Packard and Ivan Illich, this paper explores this "normative invasion" of human life by technique as a feature of contemporary information technology politics, specifically in (1) the historical context of normative and material technological colonization, and (2) the intertwining of propaganda and information warfare in the current reshaping of information politics.
Chaves M.S.,Atlantic University |
Freitas L.,Grande Rio University |
Vieira R.,Grande Rio University
KEOD 2012 - Proceedings of the International Conference on Knowledge Engineering and Ontology Development | Year: 2012
Ontologies have been used to support both web agents reasoning and human decision making. However, ontology development is a new area and for some knowledge domains they are still rare. Although ontologies had been developed in the context of Semantic Web, it is the Web 2.0 content that is actually pervasive on the web. One of the properties of this content is to be multilingual, which requires multilingual resources to deal with it. Online reviews are examples of multilingual texts provided by products and services consumers. This paper presents a multilingual ontology for the accommodation sector. As a result, we deliver Hontology, a freely available domain-specific ontology. Hontology reuses concepts of other vocabularies such as Dbpedia.org and Schema.org. It is useful for a wide range of applications within the accommodation sector, including ontology-based information extraction, text annotation and information visualisation.