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Twelve endurance athletes and six power athletes performed fatiguing isokinetic knee flexions/extensions. Isokinetic torque was recorded during the exercise. Isometric torque, cortisol and lactate responses, electromyographic (EMG) mean power frequency, average rectified value, and conduction velocity were analysed before and after the isokinetic exercise to determine correlations between electrophysiological variables and mechanical performances and/or blood concentrations of biomarkers in the two groups of athletes. The EMG variables were estimated from signals recorded from the vastus lateralis in both voluntary and electrically elicited isometric contractions. Power athletes recorded higher values than endurance athletes for the following variables: pre-exercise isometric maximal voluntary contraction (MVC), isokinetic MVC, rate of mechanical fatigue during isokinetic contractions, pre - post exercise variations and recovery times of conduction velocity and mean power frequency, and lactate concentrations. Moreover, conduction velocity overshooting was observed in endurance athletes during the recovery phase after exercise. The correlation analyses showed that the higher the rate of mechanical fatigue, the higher the lactate production and the reduction in conduction velocity due to the exercise. 相似文献
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Mellone Maria Ramploud Alessandro Carotenuto Gemma 《Educational Studies in Mathematics》2021,106(3):379-396
Educational Studies in Mathematics - We will present cultural transposition as a particular perspective to frame the use of foreign mathematics education practices as an opportunity for questioning... 相似文献
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Elisa Cimetta Mauro Franzoso Marta Trevisan Elena Serena Alessandro Zambon Stefano Giulitti Luisa Barzon Nicola Elvassore 《Biomicrofluidics》2012,6(2):024127-12
Advanced cell culture systems creating a controlled and predictable microenvironment together with computational modeling may be useful tools to optimize the efficiency of cell infections. In this paper, we will present a phenomenological study of a virus-host infection system, and the development of a multilayered microfluidic platform used to accurately tune the virus delivery from a diffusive-limited regime to a convective-dominated regime. Mathematical models predicted the convective-diffusive regimes developed within the system itself and determined the dominating mass transport phenomena. Adenoviral vectors carrying the enhanced green fluorescent protein (EGFP) transgene were used at different multiplicities of infection (MOI) to infect multiple cell types, both in standard static and in perfused conditions. Our results validate the mathematical models and demonstrate how the infection processes through perfusion via microfluidic platform led to an enhancement of adenoviral infection efficiency even at low MOIs. This was particularly evident at the longer time points, since the establishment of steady-state condition guaranteed a constant viral concentration close to cells, thus strengthening the efficiency of infection. Finally, we introduced the concept of effective MOI, a more appropriate variable for microfluidic infections that considers the number of adenoviruses in solution per cell at a certain time. 相似文献
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Francesco Piraino ?eila Selimovi? Marco Adamo Alessandro Pero Sam Manoucheri Sang Bok Kim Danilo Demarchi Ali Khademhosseini 《Biomicrofluidics》2012,6(4)
The application of microfluidic technologies to stem cell research is of great interest to biologists and bioengineers. This is chiefly due to the intricate ability to control the cellular environment, the reduction of reagent volume, experimentation time and cost, and the high-throughput screening capabilities of microscale devices. Despite this importance, a simple-to-use microfluidic platform for studying the effects of growth factors on stem cell differentiation has not yet emerged. With this consideration, we have designed and characterized a microfluidic device that is easy to fabricate and operate, yet contains several functional elements. Our device is a simple polyester-based microfluidic chip capable of simultaneously screening multiple independent stem cell culture conditions. Generated by laser ablation and stacking of multiple layers of polyester film, this device integrates a 10 × 10 microwell array for cell culture with a continuous perfusion system and a non-linear concentration gradient generator. We performed numerical calculations to predict the gradient formation and calculate the shear stress acting on the cells inside the device. The device operation was validated by culturing murine embryonic stem cells inside the microwells for 5 days. Furthermore, we showed the ability to maintain the pluripotency of stem cell aggregates in response to concentrations of leukemia inhibitory factor ranging from 0 to ∼1000 U/ml. Given its simplicity, fast manufacturing method, scalability, and the cell-compatible nature of the device, it may be a useful platform for long-term stem cell culture and studies. 相似文献
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Tiago Roux Oliveira Alessandro Jacoud Peixoto Liu Hsu 《Journal of The Franklin Institute》2012,349(4):1397-1415
This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input–single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities. We demonstrate that it is possible to achieve an arbitrarily small neighborhood of the desired optimal point using only output-feedback. The key idea is the combination of a periodic switching function with a norm state observer. As an important advantage, we show that the proposed scheme achieves extremum-seeking for all initial conditions, i.e., the real-time optimization algorithm has global convergence properties. An application to a simple nonderivative optimizer illustrates the viability of the proposed approach. 相似文献
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Elisabetta Conte Ilaria Grazzani Alessandro Pepe 《Early education and development》2018,29(6):814-830
Research Findings: In this study, we investigated associations among social cognition skills (specifically, emotion knowledge and theory of mind), language abilities, and 3 varieties of prosocial behavior (helping, sharing, and comforting) in early childhood. The effects of age and gender were also taken into account. Participants were 149 Italian children between 24 and 47 months of age (M = 35.6 months, SD = 6.77 months). We adopted a multitrait mixed-methods research design, using direct measures of emotion knowledge, theory of mind, and language as well as naturalistic observations of children’s free play with peers to detect the frequency with which they engaged in prosocial behaviors. Ordinal logistic regression analyses showed that helping behaviors were especially accounted for by emotion knowledge and gender, whereas variance in sharing behaviors was mostly explained by theory-of-mind ability and language. Practice or Policy: The findings encourage those involved in early childhood education to develop training and intervention programs to enhance children’s emotional, linguistic, and cognitive skills. Given that these results were obtained with children as young as 2 and 3 years, preventive intervention should be implemented during the earliest years of life. 相似文献