199 research outputs found

    Perfis de força: velocidade no sprint em jogadores portugueses de futebol e futsal: um estudo piloto transversal

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    Background: Sprint running is a key factor of performance for team sports as football and futsal. Force-power-velocity relationships and mechanical effectiveness have been recently used to analyse force-velocity (F-V) profiles. The aim of this study was two-fold: (1) to quantify the sprint mechanical F-V profiles in Portuguese football and futsal players; (2) to analyse differences among sexes, competitive levels and sports on sprint mechanical variables in Portuguese football and futsal players. Methods: Four football players (2 mens) and four futsal players (2 mens), aged 26 ± 4.24 years, performed a 3 maximal sprints of 30 m from a standing position with 4 min of rest between successive sprints. Video data was collected with a Go Pro Hero (Full HD 1080p, 30 fps). Force-velocity profile was obtained with time motion data: F0 (N/kg), V0 (m/s), Pmax (W/kg), Sfv, RFmax (%), DRF (%), Vopt (m/s) and max speed (m/s). Results: Men’s players showed a higher V0 (t = -7.12;p<0.001,d=5.04),Vopt (t=-2.90;p≤ 0.05,d=2.05)andmaxspeed(t=-5.09;p≤ 0.05, d = 3.60) than women players. No differences with statistical significance were observed among competitive levels and sports. Conclusion: These results showed that the sprint mechanical F-V profiles is able to distinguish between men and women football and futsal players. No differences among competitive levels could be due to the low competitive level of the sample. Future research should include different competitive level such as elite, sub-elite and recreational.Enqudramento – O sprint é um fator determinante para o desempenho em desportos coletivos como o futebol e o futsal. As relações força-potência-velocidade e eficácia mecânica têm sido recentemente utilizadas para analisar perfis de força-velocidade (F-V). O objetivo deste estudo era duplo: (1) quantificar os perfis biomecânicos F-V do sprint em jogadores de futebol e futsal portugueses; (2) analisar diferenças entre sexos, níveis competitivos e desportos nas variáveis em estudo. Métodos – 4 jogadores de futebol (2 homens) e 4 jogadores de futsal (2 homens), com 26 ± 4,24 anos, realizaram 3 sprints máximos de 30 m a partir de uma posição de pé com 4 min de descanso entre sprints sucessivos. Foram recolhidos dados de vídeo com um Go Pro Hero (Full HD 1080p, 30 fps). O perfil de força- velocidade foi obtido com: F0 (N/kg), V0 (m/s), Pmax (W/kg), Sfv, RFmax (%), DRF (%), Vopt (m/s) e velocidade máxima (m/s). Results – Os jogadores masculinos mostraram umV0 (t=-7,12;p<0,001,d=5,04),Vopt (t=- 2,90; p ≤ 0,05, d = 2,05) e velocidade máxima (t =-5,09;p≤0,05,d=3,60)maisaltadoque nas jogadoras femininas. Não foram observadas diferenças com significado estatístico entre os níveis competitivos e o desporto. Conclusão – Estes resultados mostraram que os perfis mecânicos de sprint (F-V) são capazes de diferenciar entre jogadores masculinos e femininos de futebol e jogadores de futsal. Nenhuma diferença entre os níveis competitivos pode dever-se ao baixo nível competitivo da amostra. A investigação futura deve incluir diferentes níveis competitivos, tais como elite, subelite e recreativo.info:eu-repo/semantics/publishedVersio

    Visceral Abdominal and Subfascial Femoral Adipose Tissue Have Opposite Associations with Liver Fat in Overweight and Obese Premenopausal Caucasian Women

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    Abdominal obesity has been associated with liver fat storage. However, the relationships between other body composition depots and metabolic syndrome features with hepatic fat are still unclear. We examined abdominal and thigh adipose tissue (AT) compartments associations with liver fat in 140 overweight and obese premenopausal Caucasian women. Blood lipids and, proinflammatory and atherothrombotic markers associations with hepatic fat were also analyzed. A larger visceral AT (VAT) was related with liver fat (P < 0.05). Contrarily, thigh subfascial AT was inversely related to liver fat (P < 0.05). Increased fasting insulin, triglycerides, PAI-1 concentrations, and a higher total-cholesterol/HDL-cholesterol ratio were also associated with hepatic fat, even after adjustment for VAT (P < 0.05). Thigh subfascial adiposity was inversely associated with liver fat, suggesting a potential preventive role against ectopic fat storage in overweight and obese women. These results reinforce the contribution of an abdominal obesity phenotype associated with a diabetogenic and atherothrombotic profile to liver lipotoxicity

    Correction to: Role of root hair elongation in rhizosheath aggregation and in the carbon flow into the soil

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    The above article’s initial published version contained an error regarding the co-author Vincent J. M. N. L. Felde’s affiliation. Instead of “Institute of Soil Science and Soil Conservation, Justus Liebig University Giessen, Giessen, Germany”, the right affiliation should have been “Institute of Soil Science, Leibniz University of Hannover, Germany”. The original article has been corrected

    Technological trends, global market, and challenges of bio-ethanol production

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    Ethanol use as a fuel additive or directly as a fuel source has grown in popularity due to governmental regulations and in some cases economic incentives based on environmental concerns as well as a desire to reduce oil dependency. As a consequence, several countries are interested in developing their internal market for use of this biofuel. Currently, almost all bio-ethanol is produced from grain or sugarcane. However, as this kind of feedstock is essentially food, other efficient and economically viable technologies for ethanol production have been evaluated. This article reviews some current and promising technologies for ethanol production considering aspects related to the raw materials, processes, and engineered strains development. The main producer and consumer nations and future perspectives for the ethanol market are also presented. Finally, technological trends to expand this market are discussed focusing on promising strategies like the use of microalgae and continuous systems with immobilized cells

    Methodology for phytoplankton taxonomic group identification towards the development of a lab-on-a-chip

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    This paper presents the absorbance and fluorescence optical properties of various phytoplankton species, looking to achieve an accurate method to detect and identify a number of phytoplankton taxonomic groups. The methodology to select the excitation and detection wavelengths that results in superior identification of phytoplankton is reported. The macroscopic analyses and the implemented methodology are the base for designing a lab-on-a-chip device for a phytoplankton group identification, based on cell analysis with multi-wavelength lighting excitation, aiming for a cheap and portable platform. With such methodology in a lab-on-a-chip device, the analysis of the phytoplankton cells’ optical properties, e.g., fluorescence, diffraction, absorption and reflection, will be possible. This device will offer, in the future, a platform for continuous, autonomous and in situ underwater measurements, in opposition to the conventional methodology. A proof-of-concept device with LED light excitation at 450 nm and a detection photodiode at 680 nm was fabricated. This device was able to quantify the concentration of the phytoplankton chlorophyll a. A lock-in amplifier electronic circuit was developed and integrated in a portable and low-cost sensor, featuring continuous, autonomous and in situ underwater measurements. This device has a detection limit of 0.01 µ/L of chlorophyll a, in a range up to 300 µg/L, with a linear voltage output with chlorophyll concentration.European Regional Development Fund (ERDF) through the Interreg VA Spain-Portugal (POCTEP) 2014–2020 Program under grant agreement 0591_FOODSENS_1_E, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020, and by project NORTE-08-5369-FSE-000039 co-founded by the European Social Fund FSE and through National funds NORTE 2020 and Regional Operacional Programa of North 2014/2020. The University of Vigo work was funded by a Xunta de Galicia grant to the Biological Oceanography Research Group (Consolidación e estruturación de unidades). This output reflects only the views of the authors, and the program authorities cannot be held responsible for any use that may be made of the information contained therei

    Distinctive features of composts of different origin: a thorough examination of the characterization results

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    The potential of composts produced from different origin residues to be used in environmentally friendly agriculture is addressed in this work. Seven composts obtained from different raw materials and composting methodologies are compared using elemental, thermal and spectroscopic characterization data. Despite the stabilization of the organic matter in all composts being adequate for agricultural applications, they display distinct elemental and structural compositions. Likewise, the fertilisers have very different effects on lettuce growth. Despite the observed differences, some common features were found, namely a mass loss (TGA) of 25.2 g per mol C, association between groups of elements (Fe, Al, Ni, Co, Cr, Cu and S; Mg, Na, K and P, C, Coxi, N and Pb) and correlations between the amount of carbon nanostructures and the characteristic aromaticity parameters. These results suggest that the tuning of the compost features for specific cultures may be possible for sustainable food production.This work was financially supported by the Interreg VA Spain-Portugal Programme (EU) through the project Res2ValHum (0366_RES2VALHUM_1_P). A.C. Silva acknowledges receipt of a PhD grant (UMINHO/BD/40/2016) financed by the Operational Programme Norte 2020 (through the Project “NORTE-08-5369-FSE-000033”). A. Teixeira acknowledges the grant (Res2ValHum 01/2018) to develop experimental work for 11 months on the project. J. Antelo and S. Fiol are also grateful for the financial support provided by Xunta de Galicia—Consellería de Educación e Ordenación Universitaria de Galicia (Consolidation of Competitive Groups of Investigation; GI-1245, ED431C 2018/12 and CRETUS AGRUP2015/02, ref. 2018-PG10)

    SiOx Patterned Based Substrates Implemented in Cu(In,Ga)Se2 Ultrathin Solar Cells: Optimum Thickness

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    Interface recombination in sub-µm optoelectronics has a major detrimental impact on devices’ performance, showing the need for tailored passivation strategies to reach a technological boost. In this work, SiOx passivation based substrates were developed and integrated into ultrathin Cu(In,Ga)Se2 (CIGS) solar cells. This study aims to understand the impact of a passivation strategy, which uses several SiOx layer thicknesses (3, 8, and 25 nm) integrated into high performance substrates (HPS). The experimental study is complemented with 3D Lumerical finite-difference time-domain (FDTD) and 2D Silvaco ATLAS optical and electrical simulations, respectively, to perform a decoupling of optical and electronic gains, allowing for a deep discussion on the impact of the SiOx layer thickness in the CIGS solar cell performance. This study shows that as the passivation layer thickness increases, a rise in parasitic losses is observed. Hence, a balance between beneficial passivation and optical effects with harmful architectural constraints defines a threshold thickness to attain the best solar cell performance. Analyzing their electrical parameters, the 8 nm novel SiOx based substrate achieved a light to power conversion efficiency value of 13.2 %, a 1.3 % absolute improvement over the conventional Mo substrate (without SiOx).info:eu-repo/semantics/submittedVersio

    The silent extinction of freshwater mussels in Portugal

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    Freshwater mussels are one of the most threatened animal groups in the world. In the European Union, threatened and protected mussel species are not adequately monitored, while species considered to be common and widespread receive even less attention. This is particularly worrying in the Mediterranean region, where species endemism is high and freshwater habitats are severely affected by water scarcity. In the absence of hard data on population trends, we report here a long-term comparison of freshwater mussel assemblages at 132 sites covering 15 different hydrological basins in Portugal. This study reveals a widespread decline of 60 % in the number of sites and 67 % in the overall abundance of freshwater mussels across Portugal over the last 20 years, indicating that all species are rapidly declining and threatened with extinction. These results show that current legislation and conservation measures are largely ineffective and highlight the importance of updating the Habitats Directive to enforce standard monitoring protocols for threatened species in the European Union and to extend monitoring to other freshwater species thought to be common and widespread. Efficient water management, restrictions on irrigation expansion in important biodiversity areas, mitigation of hydrological changes and loss of aquatic habitat connectivity caused by physical alterations are urgently needed to reverse these declining population trends. For the severely endangered species Margaritifera margaritifera, Potomida littoralis, and Unio tumidiformis, where populations are now critically low, more urgent action is needed, such as ex-situ conservation, protection of remaining populations and large-scale habitat restoration.We would like to thank Jake Dimon, José Tourais, Filipe Rolo, and Elza Fonseca for their help in the surveys. This research was developed under the project EdgeOmics - Freshwater Bivalves at the edge: Adaptation genomics under climate-change scenarios (PTDC/CTA-AMB/3065/2020) funded by the Portuguese Foundation for Science and Technology (FCT) through national funds. FCT also funded MLL under contract 2020.03608.CEECIND, EF under contract CEECINST/00027/2021/CP2789/CT0003, AGS under the grants SFRH/BD/137935/2018 and COVID/DB/152933/2022, and JGN under the grant 2020.04637. BD. The baseline survey was funded by the project “Documentos Estruturantes” (POA 1.100021) of the Instituto da Conservaçã da Natureza

    Optoelectronic simulations for novel light management concepts in Cu(In,Ga)Se2 solar cells

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    One of the trends making its way through the Photovoltaics (PV) industry, is the search for new application possibilities. Cu(In,Ga)Se2 (CIGS) thin film solar cells stand out due to their class leading power conversion efficiency of 23.35 %, flexibility, and low cost. The use of sub-μm ultrathin CIGS solar cells has been gaining prevalence, due to the reduction in material consumption and the manufacturing time. Precise CIGS finite-difference time-domain (FDTD) and 3D-drift diffusion baseline models were developed for the Lumerical suite and a 1D electrical model for SCAPS, allowing for an accurate description of the optoelectronic behavior and response of thin and ultrathin CIGS solar cells. As a result, it was possible to obtain accurate descriptions of the optoelectronic behavior of thin and ultrathin solar cells, and to perform an optical study and optimization of novel light management approaches, such as, random texturization, photonic nanostructures, plasmonic nanoparticles, among others. The developed light management architectures enabled to push the optical performance of an ultrathin solar cell and even surpass the performance of a thin film solar cell, enabling a short-circuit current enhancement of 6.15 mA/cm2 over an ultrathin reference device, without any light management integrated.publishe
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