Linear Invariant Systems Theory for Signal Enhancement

This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na análise de técnicas de sub-espaço. A resposta em frequência dos filtros resultantes da decomposição em valores singulares é obtida aplicando as propriedades dos sistemas LTI

SSA of biomedical signals: A linear invariant systems approach

Singular spectrum analysis (SSA) is considered from a linear invariant systems perspective. In this terminology, the extracted components are considered as outputs of a linear invariant system which corresponds to finite impulse response (FIR) filters. The number of filters is determined by the embedding dimension.We propose to explicitly define the frequency response of each filter responsible for the selection of informative components. We also introduce a subspace distance measure for clustering subspace models. We illustrate the methodology by analyzing lectroencephalograms (EEG).FCT - PhD scholarship (SFRH/BD/28404/2006)FCT - PhD scholarship (SFRH/BD/48775/2008

Identifying evoked potential response patterns using independent component analysis and unsupervised learning

Independent Component Analysis(ICA) is a pre-processing step widely used in brain studies. One of the most common problems in artifact elimination or brain activity related studies is the ordering and identification of the independent components(ICs). In this work, a novel procedure is proposed which combines ICA decomposition at trial level with an unsupervised learning algorithm (K-means) at participant level in order to enhance the related signal patterns which might represent interesting brain waves. The feasibility of this methodology is evaluated with EEG data acquired with participants performing on the Halstead Category Test. The analysis shows that it is possible to find the Feedback Error Negativity (FRN) Potential at single-trial level and relate its characteristics with the performance of the participant based on their knowledge of the abstract principle underlying the task.info:eu-repo/semantics/publishedVersio

Coexistência de duas espécies exóticas de lagostins (Pacifastacus leniusculus e Procambarus clarkii) na bacia hidrográfica do rio Sabor (NE Portugal)

Em Portugal existia uma única espécie europeia de lagostim de água doce, Austropotamobius pallipes, o lagostim-de-patas-brancas, que se considera actualmente extinta no país. No nordeste de Portugal continental onde anteriormente ocorria esta espécie, os cursos de água estão actualmente a ser colonizados por duas espécies de lagostins norte americanos. Na década de 70, proveniente de Espanha onde foi intencionalmente introduzido, o lagostim-vermelho-da-Luisiana, Procambarus clarkii, colonizou rapidamente os rios do sul de Portugal, propagando-se depois por todas as massas hídricas do país. Em 1994, as autoridades espanholas introduziram uma outra espécie, o lagostim sinal, Pacifastacus leniusculus, na província de Zamora, que foi detectada em Portugal, no rio Maçãs (Bacia do Sabor) três anos depois. A propagação e evolução das populações destas espécies no rio Maçãs têm sido seguidas anualmente desde 2000. P. clarkii, espécie sub-tropical, nunca atingiu neste curso abundâncias muito elevados. Pelo contrário, P. leniusculus, espécie de águas mais frias, apresenta valores mais elevados, cerca de seis vezes superiores aos de P.clarkii. O lagostim sinal encontra-se bem adaptado, continuando a sua expansão neste rio e prevendo-se que venha a colonizar outras massas hídricas adjacentes. A expansão do lagostim vermelho de jusante para montante parece ser menos efectiva, não tendo, desde 2005, sido observado em novos locais deste rio. A coexistência das duas espécies verifica-se actualmente num troço fluvial de cerca de 45 km de extensão, apesar das diferenças notórias ao nível das características dos seus habitats

Dispersal and coexistence of two non-native crayfish species (Pacifastacus leniusculus and Procambarus clarkii ) in NE Portugal over a 10-year period

NE Portugal is one of the most isolated and low populated regions of Western Europe. Recently, two American crayfish species reached this area: signal crayfish Pacifastacus leniusculus coming from Spain and red swamp crayfish Procambarus clarkii in its northward expansion. The dispersion of both species was followed throughout the last decade in river Maçãs (Douro catchment). Our results support the hypothesis of faster downstream colonisation. The mean spread rate of signal crayfish was faster for the downstream expansion, 2.8 km·yr-1, while the upstream rate was 1.7 km·yr-1. Exceptionally, in one period, the rate of spread reached 6.7 km·yr-1, which was apparently caused by downstream washing in extreme conditions of flow. The mean rate of spread is higher than the observed in other studies which may also be related to the low current velocity of late spring and summer that provides favourable conditions for a fast upstream colonisation. Coexistence of signal and red swamp crayfish was detected in a large river sector. Signal crayfish strongly dominates in the upper and intermediate sectors which are the colder part of the river and in the lower sectors, species abundances are not significantly different. Winter temperature in the higher altitude reaches seems to moderate the competitive abilities of P. clarkii

Colonization and dispersal rates of two non-native crayfish species (Pacifastacus leniusculus and Procambarus clarkii) in NE Portugal

In Europe, a generalized regression of the native crayfish was observed during the past decades. Simultaneously, several non-native species spread in most countries. In Portugal, the red swamp crayfish, Procambarus clarkii, is now occurring in most inland waters. The NE Portugal is one of the most isolated and low populated regions of Western Europe. Most rivers in these region present low levels of human impact and some are actually pristine. Recently, two American crayfish species reached the area: signal crayfish (Pacfastacus leniusculus) coming from Spain and red swamp crayfish. The isolation and the natural conditions of these rivers make them particularly valuable for the study of crayfish colonization and spreading. The colonization by both species was followed throughout the last decade in the Maçãs river (Douro catchment). Sampling was undertaken every year with baited traps. The average dispersal rate of signal crayfish was approximately 2 km/year, although a great variability among sectors was observed. Coexistence of signal and red swamp crayfish was detected in a large part of the river system. Signal crayfish developed well adapted and persistent populations. The lower abundance of red swamp crayfish is apparently caused by the low winter temperatures

Movement and interaction of two exotic crayfish (Pacifastacus leniusculus and Procambarus clarkii) using PIT telemetry in experimental conditions

The coexistence of two exotic crayfish species (Procambarus clarkii and Pacifastacus leniusculus) was observed in a stretch of Rio Maçãs (Douro basin, Northeast of Portugal). The red swamp crayfish, P. clarkii, a sub-tropical species, was first detected in 1979 in Rio Caia (Alentejo) and from there rapidly spread through most freshwater bodies. This species is extremely resistant to severe climatic conditions, living in such contrasting environments as South or Northeast streams of Portugal. The signal crayfish, Pacifastacus leniusculus, a cold-water crayfish recently reached Portuguese waters and is now spreading in Rio Maçãs. To characterise movements, activity patterns and interactions of both species an experiment was developed in a confined area using PIT telemetry equipment with a multi-point decoder unit connected to eight circular panel antennae. Data were collected from sympatric tagged populations monitored during several days, to detect interactions between individuals during night and day

ASSESSMENT OF ECOLOGICAL CONDITIONS OF PERMANENT MEADOWS IN THE ITALIAN ALPS: LOSS, BIODIVERSITY AND REMOTE SENSING CHANGE DETECTION

The monitoring of ecological condition of grasslands ecosystems in the European Alps is a main issue for mountain regions, since the abandonment of traditional and sustainable management practices has exposed grassland habitat to significant impacts in a context of global environmental change. The present research project was focused in assessment of the state of permanent meadows in the lowlands of Valtellina Valley (80 km2), Italian Alps, during the timeframe 1980-2000. In specific, it quantified the land use/land cover changes and identified main drivers behind permanent meadows loss; characterized the relationship between biodiversity in the meadows and the spatial-environmental conditions in the landscape and by last evaluated the use of satellite remote sensing data for fast change detection in landscape. To achieve such aims, the research project was organized in three different approaches presented in the four chapters of this thesis. Concerning the quantification of the land use/land cover and identification of main drivers behind permanent meadows loss, the results show a strong decrease in meadows (-18.5%) in a context of agricultural land decrease and human settlements increase. This was the land cover type with highest loss and conversion rate during the study period. Meadows were converted to human settlements (urban, industrial and roads), other agriculture uses (cultivation, orchard, vineyard), bushland and uncultivated land. Meadows loss occurred mainly in soils with good land capability, low slope, exposed to south and in proximity of roads, urban settlements and bushland. Densities of urban, industrial and bushland and land capability were the only significant drivers for meadows loss, while distance to meadow edge, meadows density, distance to roads and soil degradation were the only significant drivers for meadows preservation. Concerning the characterization of the relationship between biodiversity in the meadows and the spatial-environmental conditions in the landscape, the results evidenced that species richness and Shannon indices were best explained by regressive models including changes occurred in spatial environmental heterogeneity from 1980 to 2000. Species richness was negatively related to strong decrease in meadows habitat area and recent urban area, while Shannon index was positively related to the increase in landscape diversity. In contrast, species evenness was better explained by regressive model including recent spatial environmental heterogeneity and positively related to increase ineastness in the study area, and negatively affected both by the area of woody and soil pH (KCl). Concerning the evaluation of the use of satellite remotely sensing data for land cover mapping and change detection in landscape, the results show that the hybrid approach for land cover classification based of Landsat imagery was highly accurate. Image differencing is the technique which best detect changes in landscape as well as in urban, meadow and bush land. The accuracy of change detection was moderate. This thesis concludes that the conflict by land in locations densely occupied by other land cover types with good land capability is the major threat to meadows and avoidance of fragmentation may be a good strategy for its preservation. The meadows habitat needs a well-designed landscape and farming planning, which should account the economic value of the ecosystem services provided by this habitat. In addition, to conserve plant diversity in meadows it is necessary to avoid loss of meadows habitat, maintain landscape diversity and execute a sustainable meadow management. Remotely sensed imagery can be a reliable source of information for alps, although particular attention should be made to the image pre-processing and classification, as well as, to minimize topography effects in spectral information

Injury risks for fitness instructors: a review of key factors

The labour risks control is an occupational health concern. Fitness participants have been increasing in the last years (Lindwall, 2004). Clients’ demand and the increase in classes number take the fitness instructors (FI) to a higher injuries exposure due to high workload. It is possible to observe several variations in aerobic dance, cycling, pilates, strength training, flexibility and balance. The main differences are in the cardiovascular intensities and the low to high impact dance (Van Mechelen, Hlobil & Kemper, 1992). The FI are exposed to high volumes of classes and injuries risks due to the high number of students and classes (Couto et al., 2016). As far as our understanding goes, FI are 50% more prone to injuries incidence in comparison to students. Thus, the aim of this study was to assess by a bibliographic research the health and injuries risk in FI. This is a bibliographic review made in PUBMED, Google Scholar, SCIELO and Web of Science. The used keywords were “fitness instructors injuries”, “fitness professor’s injuries”, and “fitness instructor’s risks”. From an analysis of 23 papers, ten were chosen considering title and abstract. After a full integral analysis, only five papers were selected for revision. The others did not aimed to analyse the injuries and the health risks for FI. The selected papers approached the injuries and health risk factors for FI. There is a positive and significant correlation between the formation levels and injuries incidence prevention in FI and students (Malek, Nalbone, Berger & Coburn, 2002). FI with higher classification prevent higher frequency of injuries events. The injuries prevalence was superior in FI than in students (72.4 – 75.9% and 22.8 – 43.3% respectively) (Mutoh, Sawai, Takanashi & Skurko, 1998; Francis, Francis & Welshons-Smith, 1985). The injuries were general inflammations, muscle strains or sprains and stress fractures by overuse (Rothenberger, Chang & Cable, 1988). The FI are more exposed to injuries than students are (0.17 injuries/100h vs 0.15/100h of practice, respectively) and about 77% of the injuries were in the lower limbs (Garrick, Gillien & Whiteside, 1986). There is a lack of research in FI injuries risk of factors. However, FI seem to have a higher exposure to injuries in comparison to students. The high workload seem to be determinant to the incidence of overuse injuries.info:eu-repo/semantics/publishedVersio

The effects of 6-month multi-component exercise intervention on body composition in aged women: a single-arm experimental with follow-up study

Multicomponent exercise programs, which combine multiple modalities such as aerobic exercises, strength training exercises, flexibility exercises, and balance exercises, can help to promote healthy aging and prevent chronic diseases in aged women. Thus, the goal of this study is to examine if a multicomponent exercise program could improve body composition in community- dwelling aged women. A 6-month single-arm quasi-experimental research was conducted using a multicomponent exercise program for older adults. The sample included 38 women with a mean age of 63.50 years (SD = 6.47 years). Body composition and anthropometric measurement was conducted from baseline (T1), after intervention (T2), and follow-Up (T3). In addition, after exercise intervention, a significant difference with moderate to large effects was reported for fat mass [η2p = 0.374, p < 0.001)], bone density [η2p = 0.374, p < 0.05)], percentage of water [η2p = 0.374, p < 0.001)], and a metabolic equivalent task [η2p = 0.374, p < 0.05]. Additionally, a significant large effect size between T1 and T2 was verified. However, body composition indicators seem to decrease below baseline levels after concluding exercise intervention (T3). Muscle mass decreased significantly after exercise intervention and mean scores were lower compared to baseline data (T1). Thus, a positive effect of the multicomponent exercise program on body composition was established in this group of community-dwelling aged women. However, the relative improvement in body fat and muscle mass were lost after the exercise program’s conclusion for values below the baselines. Avoiding detraining periods is, therefore, fundamental to maintaining the normal relative body composition.This research was funded by national funds through the Portuguese Foundation for Science and Technology, I.P., grant number UIDB/04748/2020info:eu-repo/semantics/publishedVersio