1,545 research outputs found

    Can Heart Rate Variability Predict the Second Metabolic Threshold in Young Soccer Players?

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    International Journal of Exercise Science 11(2): 1105-1111, 2018. Heart rate variability (HRV) is an effective method to assess the influence of the autonomic nervous system, which may be directly linked to metabolic demand. The aim of the study was to determine if the second metabolic threshold can be identified by HRV. Thirteen athletes were assessed in cardiopulmonary exercise test with concomitant gas analysis. The RR intervals (RRi) were plotted in a spreadsheet for graphics analysis and the point at which there was a shift in the RRi curve was determined as RRiT2. The second ventilatory threshold (VT2) was used as the gold standard technique. A positive correlation was found in the test time (r = 0.84), heart rate (r = 0.97) and VO2 (r = 0.97) between the VT2 and HRV second threshold (RRiT2). All parameters identified by RRiT2 were lower than predicted by VT2 (p \u3c 0.05)

    Climate adaptation, transitions, and socially innovative action-research approaches

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    Climate change may be a game-changer for scientific research by promoting a science that is grounded in linking the production of knowledge and societal action in a transition toward more sustainable development pathways. Here, we discuss participatory action-research (PAR) as a way of thinking and leading investigations that may promote incremental and transformative changes in the context of climate change adaptation research. Our exploration is addressed in the Portuguese context, where PAR and sustainable transition studies are still marginal, and adaptation processes are a recent topic on political agendas. We describe the characteristics of PAR and use two studies of adaptation to illustrate how research and practice co-evolve through interactive cycles. The two studies are works in progress, rather than completed PAR processes. Climate change adaptation is an ongoing and long-term process. Moreover, in Portugal, as in many regions of the world, climate change adaptation is a fairly new topic. Thus, both case studies are now initiating a long-term process of change and adaptation. The completion of one research cycle is a realistic expectation that we have achieved in the two case study experiences. In our discussion of the case studies, we consider how these experiences provide insights into the role of PAR for long-term regime changes. We conclude by pointing to the societal needs addressed by PAR, as a pragmatically oriented and context-specific research design. The approach can be complementary to other frameworks in sustainable transition studies such as transition management. Being more pragmatically oriented, PAR cycles may influence incrementally transformative changes that can be guided by transition management’s long-term design for governing sustainable transitions

    Physical Activity in Rural African School-Aged Children and Adolescents

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    In industrialized countries, reduced levels of physical activity (PA) associated with increased prevalence of the so-called “hypokinetic diseases” stimulates the interest in research in PA and its correlate

    Time-Lagged Correlation Analysis of Shellfish Toxicity Reveals Predictive Links to Adjacent Areas, Species, and Environmental Conditions

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    This work was funded by the project “MATISSE: A machine learning-based forecasting system for shellfish safety” (DSAIPA/DS/0026/2019). The work was also supported by national funds through Fundação para a Ciência e a Tecnologia (FCT) with references CEECINST/00102/2018, CEECIND/01399/2017, UIDB/04326/2020, UIDP/04326/2020 and LA/P/0101/2020 (CCMAR), UIDB/04516/2020 (NOVA LINCS), UIDB/00297/2020 (NovaMath), and UIDB/50021/2020 (INESC-ID). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951970 (OLISSIPO project).Diarrhetic Shellfish Poisoning (DSP) is an acute intoxication caused by the consumption of contaminated shellfish, which is common in many regions of the world. To safeguard human health, most countries implement programs focused on the surveillance of toxic phytoplankton abundance and shellfish toxicity levels, an effort that can be complemented by a deeper understanding of the underlying phenomena. In this work, we identify patterns of seasonality in shellfish toxicity across the Portuguese coast and analyse time-lagged correlations between this toxicity and various potential risk factors. We extend the understanding of these relations through the introduction of temporal lags, allowing the analysis of time series at different points in time and the study of the predictive power of the tested variables. This study confirms previous findings about toxicity seasonality patterns on the Portuguese coast and provides further quantitative data about the relations between shellfish toxicity and geographical location, shellfish species, toxic phytoplankton abundances, and environmental conditions. Furthermore, multiple pairs of areas and shellfish species are identified as having correlations high enough to allow for a predictive analysis. These results represent the first step towards understanding the dynamics of DSP toxicity in Portuguese shellfish producing areas, such as temporal and spatial variability, and towards the development of a shellfish safety forecasting system.publishersversionpublishe

    Heterotic String Compactifications on Half-flat Manifolds II

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    In this paper, we continue the analysis of heterotic string compactifications on half-flat mirror manifolds by including the 10-dimensional gauge fields. It is argued, that the heterotic Bianchi identity is solved by a variant of the standard embedding. Then, the resulting gauge group in four dimensions is still E6 despite the fact that the Levi-Civita connection has SO(6) holonomy. We derive the associated four-dimensional effective theories including matter field terms for such compactifications. The results are also extended to more general manifolds with SU(3) structure.Comment: 31 page

    A hydrogen-bonded assembly of cucurbit[6]uril and [MoO2Cl2(H2O)2] with catalytic efficacy for the one-pot conversion of olefins to alkoxy products

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    The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoO2Cl2(H2O)2] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoO2Cl2(H2O)2]·CB[6]·xH2O·yHCl·z(CH3COCH3) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entities, {CB[6]·10(H2O)}, aligned in layers which are shifted relative to adjacent layers to form a brick-like pattern. The CB[6]/water hydrogen-bonded entities further engage in intermolecular interactions with water, HCl and [MoO2Cl2(H2O)2] molecules to form a three-dimensional (3D) framework. Compound 2 was characterised by thermogravimetric analysis (TGA), IR and Raman vibrational spectroscopy, and 13C{1H} CP MAS NMR. The reference complex [MoO2Cl2(H2O)2]·(diglyme)2 (1) and compound 2 were studied for the oxidative catalytic conversion of olefins (cis-cyclooctene, cyclohexene and styrene) with aqueous H2O2 as oxidant. Using alcohols as solvents, 2 was employed in a one-pot two-stage strategy for converting olefins to alkoxy products, which involves oxidation (with H2O2) and acid chemistry. Mechanistic studies were carried out using different intermediates as substrates, and the type of solvent and substrate scope were investigated. The results demonstrated the ability of the CB[6]/MoVI supramolecular adduct to function as an acid-oxidation multifunctional catalyst, and its recovery and reuse via relatively simple procedures.We acknowledge the support of CICECO – Aveiro Institute of Materials [FCT (Fundação para a Ciência e a Tecnologia) Ref. UID/CTM/50011/2019], REQUIMTE-LAQV (UID/QUI/50006/2019), Centre of Marine Sciences – CCMAR (UID/Multi/04326/2019), and the CENTRO 2020 Regional Operational Programme (Project CENTRO-01-0145-FEDER-028031; PTDC/QUI-QOR/28031/2017), co-financed by national funds through the FCT/MEC and the European Union (EU) through the European Regional Development Fund under the Portugal 2020 Partnership Agreement. The FCT and the EU are acknowledged for a Ph.D. grant to L. S. N. (PD/BD/109666/2015). The positions held by M. M. A. and A. C. G. were funded by national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of article 23 of the Decree-Law 57/2016 of 29 August, changed by Law 57/2017 of 19 July.publishe

    Synthesis of natural ether lipids and 1-O-hexadecylglycero-arylboronates via an epoxide-ring opening approach: Potential antifouling additives to marine paint coatings

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    In this paper a new and efficient procedure for the synthesis of natural 1-O- alkyl glyceryl ethers such as chimyl (1), batyl (2) and selachyl (3) is described. Alkyl glycidyl ethers (4-6) were synthetized using solvents free reactions. A stereospecific ring-opening reaction of epoxides (4-6) with phenylboronic acid in dry dioxane, giving rise to cyclic arylboronates in high yields (90-98%). Seven new 1-O-hexadecylglycero-arylboronates (7-f) and chimyl alcohol (1) were evaluated in laboratory antifouling assays

    Plasmonic/magnetic liposomes based on nanoparticles with multicore-shell architecture for chemo/thermotherapy

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    In this work, multicore magnetic nanoparticles (NPs) of manganese ferrite were prepared using carboxymethyl-dextran and melamine as agglutinating agents.Magnetoliposome-like structures containing the multicore NPs exhibit sizes in the range 250 – 400 nm, being suitable for biomedical applications.FCT under Strategic funding of CF-UM-UP (UIDB/04650/2020

    Use of ionic liquids and deep eutectic solvents in polysaccharides dissolution and extraction processes towards sustainable biomass valorization

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    A shift to a bioeconomy development model has been evolving, conducting the scientific community to investigate new ways of producing chemicals, materials and fuels from renewable resources, i.e., biomass. Specifically, technologies that provide high performance and maximal use of biomass feedstocks into commodities with reduced environmental impact have been highly pursued. A key example comprises the extraction and/or dissolution of polysaccharides, one of the most abundant fractions of biomass, which still need to be improved regarding these processes' efficiency and selectivity parameters. In this context, the use of alternative solvents and the application of less energy-intensive processes in the extraction of polysaccharides might play an important role to reach higher efficiency and sustainability in biomass valorization. This review debates the latest achievements in sustainable processes for the extraction of polysaccharides from a myriad of biomass resources, including lignocellulosic materials and food residues. Particularly, the ability of ionic liquids (ILs) and deep eutectic solvents (DESs) to dissolve and extract the most abundant polysaccharides from natural sources, namely cellulose, chitin, starch, hemicelluloses and pectins, is scrutinized and the efficiencies between solvents are compared. The interaction mechanisms between solvent and polysaccharide are described, paving the way for the design of selective extraction processes. A detailed discussion of the work developed for each polysaccharide as well as the innovation degree and the development stage of dissolution and extraction technologies is presented. Their advantages and disadvantages are also identified, and possible synergies by integrating microwave- and ultrasound-assisted extraction (MAE and UAE) or a combination of both (UMAE) are briefly described. Overall, this review provides key information towards the design of more efficient, selective and sustainable extraction and dissolution processes of polysaccharides from biomass.publishe
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