627 research outputs found

    Monitoring the internal and external loads of young team handball players during competition

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    This study aimed to examine the internal- and external-training-load (ITL and ETL, respectively) during a match of young handball players. Field testing included heart-rate monitoring (memory belt, Suunto) as a marker of ITL and accelerometry (motion-biosensor, Actical Respironcis, Philips) as a marker of ETL. Time motion analysis data were obtained by recording the player's game activities and later analysed with the Matlab software package. T-test and Pearson-product-moment correlation coefficient were used to examine the differences and the relationship between variables collected in the study. The t-test analysis did not show significant differences between the total distance covered (2216.42-2135.42 m), steps conducted (1829.25-1829.83 steps), steps per minute (91.46-91.49 steps/min), energy expenditure (92.24-90.87 METS), time spent in higher intensity zones calculated by motion biosensor (13.08-12.75 minutes), training-load calculated by Edwards TRIMP method (91.54-88.56 scores) in the first and in the second half of the match. Physical activity variables show no significant correlations with the data assessed by heart rate monitors. Similar results in monitored training-load variables in the first and second halves are connected with the game intensity, which was consistent throughout the match. The lack of correlations between ITL and ETL variables indicates that accelerometry is not suitable for the assessment of metabolic training load in intermittent activities, such as handball. ITL measures used in this study are more suitable for controlling load during training and competition, while the ETL parameters used are more appropriate for better understanding players activity in periods in which the players do not train; other activities can influence players fatigue and training and competition performance

    Unstructured un-split geometrical Volume-of-Fluid methods -- A review

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    Geometrical Volume-of-Fluid (VoF) methods mainly support structured meshes, and only a small number of contributions in the scientific literature report results with unstructured meshes and three spatial dimensions. Unstructured meshes are traditionally used for handling geometrically complex solution domains that are prevalent when simulating problems of industrial relevance. However, three-dimensional geometrical operations are significantly more complex than their two-dimensional counterparts, which is confirmed by the ratio of publications with three-dimensional results on unstructured meshes to publications with two-dimensional results or support for structured meshes. Additionally, unstructured meshes present challenges in serial and parallel computational efficiency, accuracy, implementation complexity, and robustness. Ongoing research is still very active, focusing on different issues: interface positioning in general polyhedra, estimation of interface normal vectors, advection accuracy, and parallel and serial computational efficiency. This survey tries to give a complete and critical overview of classical, as well as contemporary geometrical VOF methods with concise explanations of the underlying ideas and sub-algorithms, focusing primarily on unstructured meshes and three dimensional calculations. Reviewed methods are listed in historical order and compared in terms of accuracy and computational efficiency

    Thermo-responsive, UV-active poly(phenyl acrylate)-b-poly(diethyl acrylamide) block copolymers

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    The homopolymerization of phenyl acrylate (PA) was investigated for the first time by nitroxide mediated polymerization (NMP) with the succinimidyl form of the SG1-based unimolecular initiator 2-[N-tert-butyl-2,2-(dimethylpropyl)-aminooxy]propionic acid (BlocBuilder MA). The control of PPA homopolymerization was improved by the use of 15 mol% additional free nitroxide SG1 ([tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxidanyl) and dispersities, Mw/Mn, of around 1.2 were achieved. A PPA homopolymer was then successfully chain-extended with diethyl acrylamide (DEAAm) to form a block copolymer of PPA-b-PDEAAm where the PDEAAm segment is thermo-responsive, while the PPA block is potentially UV-active. The thermo-responsive behavior of the block copolymer in 0.5 wt% aqueous solution was studied by UV-Vis spectrometry and dynamic light scattering (DLS), indicating cloud point temperatures of 26–30°C, close to that reported for PDEAAm homopolymers

    Explicit and implicit self-esteem and their associations with symptoms of anxiety and depression in children and adolescents

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    Negative self-esteem is an important transdiagnostic factor underlying various youth psychological problems. Most studies so far have examined the role of more conscious, explicit self-esteem, assessed with self-report questionnaires. Our study investigated the role of explicit as well as implicit self-esteem (with Rosenberg’s self-esteem scale and the implicit association test, respectively), and the nature of their interaction in explaining children’s and adolescents’ internalizing symptomatology. Self-esteem, depression, and anxiety symptoms were assessed in 279 youths (mean age: 13.92; 52% females). Explicit self-esteem (ESE) was consistently negatively related to internalizing symptoms, whereas implicit self-esteem (ISE) was not. For DSM-related anxiety symptoms, the interaction between ISE and ESE was significant: in youths who displayed low to average ESE, higher ISE predicted more anxiety symptoms, whereas for youths with high ESE, increased ISE was associated with lower levels of anxiety symptoms. Overall, our results suggest that explicit self-esteem is an important factor in explaining internalizing symptomatology for children and adolescents.</p

    Efficient Certified Resolution Proof Checking

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    We present a novel propositional proof tracing format that eliminates complex processing, thus enabling efficient (formal) proof checking. The benefits of this format are demonstrated by implementing a proof checker in C, which outperforms a state-of-the-art checker by two orders of magnitude. We then formalize the theory underlying propositional proof checking in Coq, and extract a correct-by-construction proof checker for our format from the formalization. An empirical evaluation using 280 unsatisfiable instances from the 2015 and 2016 SAT competitions shows that this certified checker usually performs comparably to a state-of-the-art non-certified proof checker. Using this format, we formally verify the recent 200 TB proof of the Boolean Pythagorean Triples conjecture

    Levels and changes of physical activity in adolescents during the COVID-19 Pandemic: Contextualizing urban vs. Rural living environment

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    The COVID-19 pandemic and the social distancing implemented shortly after influence physical activity levels (PALs). The purpose of this investigation was to evaluate the changes in PAL and factors associated with PALs among Croatian adolescents while considering the impact of community (urban vs. rural living environment). The sample included 823 adolescents (mean age: 16.5 ± 2.1 years) who were tested on baseline (from October 2019 to March 2020; before COVID-19 pandemic in Croatia) and follow-up (in April 2020; during the COVID-19 pandemic and imposed rules of social distancing). Baseline testing included anthropometrics, physical fitness status, and evaluation of PALs, while follow-up included only PALs (evaluated by a standardized questionnaire through an internet application). The results showed a significant influence of the living environment on the decrease of PAL, with a larger decrease in urban adolescents. Logistic regression showed a higher likelihood for normal PALs at baseline in adolescents who had better fitness status, with no strong confounding effect of the urban/rural environment. The fitness status of urban adolescents predicted their PALs at follow-up. The differences between urban and rural adolescents with regard to the established changes in PALs and relationships between the predictors and PALs are explained by the characteristics of the living communities (lack of organized sports in rural areas), and the level of social distancing in the studied period and region/country

    Application of Non-Eqilibrium Plasmas in Top-Down and Bottom-Up Nanotechnologies and Biomedicine

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    In this paper we discuss how a better understanding of thermal and mainly non-thermal plasmas provides basis for their application in a number or nanotechnologies. One should bear in mind that one may design unique properties of plasmas thus affecting very directly properties of the resulting nanostructures. A number of examples where plasmas contribute to production of nanomaterials, modification of surfaces and functionalization at nanoscales are given here. Plasmas are not a panacea but in nanotechnology their application may be the best strategy to convert production of individual structures to massively parallel production that may become a viable industrial technology

    Horizontal Tubular Bioreactors in Biotechnology

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    In this review, horizontal tubular bioreactors are discussed regarding their advantages and disadvantages compared to other bioreactor types. In horizontal tubular bioreactors medium flow is characterized by plug flow conditions that can be favorable in the case of inhibition and/or repression bioprocess kinetics. For description of liquid flow simple one-parameter or complex multi-parameters mathematical models have been established. Comparison between these models proved that complex multi-parameters model can describe real situation in the bioreactor more efficiently. Criteria of geometrical similarity are most often used for scale-up of horizontal tubular bioreactors. The successful scale-up procedure should combine the mathematical model of medium flow behavior with bioprocess kinetics in the bioreactor

    Recent developments and state of the art in flexible and conformal reconfigurable antennas

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    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Reconfigurable antennas have gained tremendous interest owing to their multifunctional capabilities while adhering to minimalistic space requirements in ever-shrinking electronics platforms and devices. A stark increase in demand for flexible and conformal antennas in modern and emerging unobtrusive and space-limited electronic systems has led to the development of the flexible and conformal reconfigurable antennas era. Flexible and conformal antennas rely on non-conventional materials and realization approaches, and thus, despite the mature knowledge available for rigid reconfigurable antennas, conventional reconfigurable techniques are not translated to a flexible domain in a straight forward manner. There are notable challenges associated with integration of reconfiguration elements such as switches, mechanical stability of the overall reconfigurable antenna, and the electronic robustness of the resulting devices when exposed to folding of sustained bending operations. This paper reviews various approaches demonstrated thus far, to realize flexible reconfigurable antennas, categorizing them on the basis of reconfiguration attributes, i.e., frequency, pattern, polarization, or a combination of these characteristics. The challenges associated with development and characterization of flexible and conformal reconfigurable antennas, the strengths and limitations of available methods are reviewed considering the progress in recent years, and open challenges for the future research are identified

    Insights into GABA receptor signalling in TM3 Leydig cells

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    gamma-Aminobutyric acid (GABA) is an emerging signalling molecule in endocrine organs, since it is produced by endocrine cells and acts via GABA(A) receptors in a paracrine/autocrine fashion. Testicular Leydig cells are producers and targets for GABA. These cells express GABA(A) receptor subunits and in the murine Leydig cell line TM3 pharmacological activation leads to increased proliferation. The signalling pathway of GABA in these cells is not known in this study. We therefore attempted to elucidate details of GABA(A) signalling in TM3 and adult mouse Leydig cells using several experimental approaches. TM3 cells not only express GABA(A) receptor subunits, but also bind the GABA agonist {[}H-3] muscimol with a binding affinity in the range reported for other endocrine cells (K-d = 2.740 +/- 0.721 nM). However, they exhibit a low B-max value of 28.08 fmol/mg protein. Typical GABA(A) receptor-associated events, including Cl- currents, changes in resting membrane potential, intracellular Ca2+ or cAMP, were not measurable with the methods employed in TM3 cells, or, as studied in part, in primary mouse Leydig cells. GABA or GABA(A) agonist isoguvacine treatment resulted in increased or decreased levels of several mRNAs, including transcription factors (c-fos, hsf-1, egr-1) and cell cycle-associated genes (Cdk2, cyclin D1). In an attempt to verify the cDNA array results and because egr-1 was recently implied in Leydig cell development, we further studied this factor. RT-PCR and Western blotting confirmed a time-dependent regulation of egr-1 in TM3. In the postnatal testis egr-1 was seen in cytoplasmic and nuclear locations of developing Leydig cells, which bear GABA(A) receptors and correspond well to TM3 cells. Thus, GABA acts via an untypical novel signalling pathway in TM3 cells. Further details of this pathway remain to be elucidated. Copyright (c) 2005 S. Karger AG, Base
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