Rijden op algen : brug tussen onderzoek en praktijk

Ze groeien razendsnel, leveren veel energie en concurreren niet met andere landbouwgewassen: algen. Alle reden om onderzoek te doen naar de potentie van algen als producent van biobrandstof. "Algen hebben veel mogelijkheden, maar er zijn nog enkele drempels te overwinnen’, weet Maria Barbosa, programmamanager Microalgen bij WUR

Variability patterns and phenology of harmful phytoplankton blooms off southern Portugal: looking for region-specific environmental drivers and predictors

Harmful algal blooms (HABs) negatively impact coastal ecosystems, fisheries, and human health, and their prediction has become imperative for effective coastal management. This study aimed to evaluate spatialtemporal variability patterns and phenology for key toxigenic phytoplankton species off southern Portugal, during a 6-year period, and identify region-specific environmental drivers and predictors. Total abundance of species responsible for amnesic shellfish poisoning (Pseudo-nitzschia spp.), diarrhetic shellfish poisoning (Dinophysis spp.), and paralytic shellfish poisoning (G. catenatum) were retrieved, from the National Bivalve Mollusk Monitoring System public database. Contemporaneous environmental variables were acquired from satellite remote sensing, model-derived data, and in situ observations, and generalized additive models (GAMs) were used to explore the functional relationships between HABs and environmental variables and identify regionspecific predictors. Pseudo-nitzschia spp. showed a bimodal annual cycle for most coastal production areas, with spring and summer maxima, reflecting the increase in light intensity during the mixed layer shoaling stage, and the later stimulatory effects of upwelling events, with a higher bloom frequency over coastal areas subjected to stronger upwelling intensity. Dinophysis spp. exhibited a unimodal annual cycle, with spring/summer maxima associated with stratified conditions, that typically promote dinoflagellates. Dinophysis spp. blooms were delayed with respect to Pseudo-nitzschia spp. spring blooms, and followed by Pseudo-nitzschia spp. summer blooms, probably reflecting upwelling-relaxation cycles. G. catenatum occurred occasionally, namely in areas more influenced by river discharges, under weaker upwelling. Statistical-empirical models (GAMs) explained 7-8%, and 21− 54% of the variability in Pseudo-nitzschia spp. and Dinophysis spp., respectively. Overall, a set of four easily accessible environmental variables, surface photosynthetically available radiation, mixed layer depth, sea surface temperature, and chlorophyll-a concentration, emerged as the most influential predictors. Additionally, over the coastal production areas along the south coast, river discharges exerted minor negative effects on both HAB groups. Despite evidence supporting the role of upwelling intensity as an environmental driver of Pseudonitzschia spp., it was not identified as a relevant model predictor. Future model developments, such as the inclusion of additional environmental variables, and the implementation of species- and period-specific, and hybrid modelling approaches, may further support HAB operational forecasting and managing over complex coastal domains.info:eu-repo/semantics/publishedVersio

Análise longitudinal da performance em nadadores de ranking mundial

A natação pura desportiva é uma modalidade cíclica onde o alcançar da máxima p e r f o rma n c e é o derradeiro objectivo. Mais ainda, o número de pesquisas de âmbito longitudinal em natação é bastante reduzido

Contribution of limbs’ actions to the four competitive swimming strokes: a nonlinear approach

The aim of our study was to assess the effect of the limbs’ actions on the nonlinear properties of the four competitive swimming strokes. Forty-nine swimmers performed all-out sprints at front-crawl, backstroke, breaststroke and butterfly, each one at full stroke (FS), only the arms’ stroke (AS), and only leg kicking (LK), in a total of 12 bouts, 6 per day. A speedo-meter cable was attached to the swimmer’s hip, to collect the speed-time raw data (f = 50Hz). Velocity, speed fluctuation, sample entropy and fractal dimension were derived from the speed-time series. Significant and moderate-strong effects were noted for both stroke and condition in all variables in the study (p ≤ 0.001; 0,560<η2 < 0,952). The four competitive strokes and their three conditions exhibited nonlinear properties. The swimming pattern was less complex and more predictable for LK in comparison to AS and FS. Breaststroke and butterfly have more complex but more predictable patterns than backstroke and front-crawl.info:eu-repo/semantics/publishedVersio

Biomechanical responses to water fitness programmes: a narrative review

In the past years, there was an increasing interest in the biomechanical responses in water fitness sessions. The present review consolidates the current “state-of-art” on the biomechanical responses in water fitness programmes. The literature was searched and screened studies on: (i) healthy subjects; and (ii) water fitness sessions and programmes reporting physical condition outcomes. A total of 36 studies met the inclusion criteria and categorized into four categories: (i) kinematics (n = 5); (ii) ground reaction force (n = 10); (iii) neuromuscular (n = 8); and (iv) strength (n = 14). There was a larger amount of evidence on strength, whereas some gaps in the body of knowledge still persist in the remaining categories. The existent studies cover a large range of age brackets (from young adults to the elderly). Women were recruited more often than men to be part of the studies. The effect of music cadence, body segments, exercise type (e.g., alternated or simultaneous), water depth, resistance equipment, and training protocols were the main topics under research.info:eu-repo/semantics/publishedVersio

Changes in classical kinematics and non‐linear parameters after a maximal 100‐m front‐crawl bout

In a linear system there is proportionality between input and output. Under this framework it is expected that the amount of change in sports performance must be proportional to variations in the inputs.info:eu-repo/semantics/publishedVersio

Changes in classical kinematics and non-linear parameters after a maximal 100-m front-crawl bout

In a linear system there is proportionality between input and output. Under this framework it is expected that the amount of change in sports performance must be proportional to variations in the inputs. However, as far as elite performance goes, this is not a straightforward assumption. Sometimes the variables selected are not sensitive enough. Hence, there is the need of having non-linear concepts underpinning such analysis. The aim was to compare classical kinematics and non-linear parameters after a maximal 100-m front-crawl bout. Twenty-four subjects (12 males and 12 females; 22.38±1.68-y) were invited to perform a 100-m freestyle race at maximal pace. Before (pre-test, i.e. rested) and immediately after (post-test, i.e. under fatigue) the maximal bout, they performed two maximal 25m swims at freestyle with push-off start. A speedo-meter cord (Swim speedo-meter, Swimsportec, Hildesheim, Germany) was attached to the swimmer’s hip (Barbosa et al., 2015) in the two 25m trials collecting the instantaneous speed. It was computed the speed fluctuation (dv; Barbosa et al., 2015), approximate entropy (ApEn; Barbosa et al., 2015) and fractal dimension (FD; Higuchi, 1988). Repeated measures ANOVAs (pre-test vs. post-test; P≤0.05), effect sizes (eta squared) and 95% of confidence intervals (95CI) were computed. The speed was 1.44±0.24 and 1.28±0.23m/s in the pre- and post/test, respectively (F=55.136, P<0.001)info:eu-repo/semantics/publishedVersio

Efeitos de um programa de 12 semanas de Hidroginástica na postura corporal de mulheres de meia-idade

À medida que a população mundial envelhece, sérias preocupações são levantadas sobre o efeito do exercício físico e de aptidão física para a saúde pública, especialmente na meia e terceira idade (Cruz-Ferreira et al., 2011). Os programas de exercícios aquáticos ganharam popularidade devido à diminuição de hipotéticos pacientes (i.e. ajudam na prevenção de patologias), e até mesmo entre indivíduos saudáveis (Costa et al., 2011). Ambos os programas, terrestres e aquáticos, baseiam-se no objetivo de alcançar e manter um nível adequado de aptidão física (incluindo a postura corporal) e, portanto, melhorar a qualidade de vida. A postura corporal tem em consideração a oscilação e/ou o alinhamento do corpo. O alinhamento do corpo representa a posição do corpo e a relação espacial entre os seus segmentos anatómicos para manter o equilíbrio, em condições estáticas ou dinâmicas, de acordo com os requisitos do ambiente e da tarefa motora. Um alinhamento adequado do corpo envolve o menor esforço (i.e. gasto energético) e sobrecarga mecânica, para otimizar a eficiência do sistema biológico. Uma postura corporal incorreta pode estar relacionada com alguma desordem a nível ortopédico (Kristensen, Bandholm, Holm, Ekdahl, & Kehlet, 2009), músculo-esquelético (Oyarzo, Villagrán, Silvestre, Carpintero, & Berral, 2013) ou neurológico (Busse, Zimdars, Zalewski, & Steffen, 2005), mas também associada com uma maior probabilidade de quedas (Sakamoto et al., 2006).info:eu-repo/semantics/publishedVersio