83 research outputs found

    Проблеми побудови відкритої та гнучкої методичної системи навчання математичних методів фізики у педагогічних університетах

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    (uk) Розглядаються тенденції розвитку фундаментальної фізико-математичної освіти, зближення природничо-наукового та гуманітарного, що уможливлюють розв’язання проблеми побудови відкритої та гнучкої науково-обґрунтованої методичної системи навчання математичних методів фізики у педагогічних університетах.(en) The article examines progressive trends of fundamental physical and mathematical education, rapprochement of naturally scientific and humanitarian, that makes possible to solve the problem of constructing the open and flexible scientifically reasonable methodical systeme of mathematical methods of physics teaching inpedagogical universities

    Social and political mechanisms for establishing ecosystem management objectives

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    While social values guide the objectives of ecosystem management, successful execution requires a public well-informed on the consequences of alternative decision options. Daniels advocates a group-learning process entitled collaborative learning to achieve this understanding. Agency personnel should assume the roles of educators, facilitators, and managers. The agencies must also open up, meditate, and share decision-making power with the public while avoiding advocacy of any particular interest-group\u27s desires. Policy makers have a role in influencing social values by fostering a nonadversarial politics of cooperation and consensus building

    Regulation of mTORC1 Signaling by pH

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    BACKGROUND: Acidification of the cytoplasm and the extracellular environment is associated with many physiological and pathological conditions, such as intense exercise, hypoxia and tumourigenesis. Acidification affects important cellular functions including protein synthesis, growth, and proliferation. Many of these vital functions are controlled by mTORC1, a master regulator protein kinase that is activated by various growth-stimulating signals and inactivated by starvation conditions. Whether mTORC1 can also respond to changes in extracellular or cytoplasmic pH and play a role in limiting anabolic processes in acidic conditions is not known. METHODOLOGY/FINDINGS: We examined the effects of acidifying the extracellular medium from pH 7.4 to 6.4 on human breast carcinoma MCF-7 cells and immortalized mouse embryo fibroblasts. Decreasing the extracellular pH caused intracellular acidification and rapid, graded and reversible inhibition of mTORC1, assessed by measuring the phosphorylation of the mTORC1 substrate S6K. Fibroblasts deleted of the tuberous sclerosis complex TSC2 gene, a major negative regulator of mTORC1, were unable to inhibit mTORC1 in acidic extracellular conditions, showing that the TSC1-TSC2 complex is required for this response. Examination of the major upstream pathways converging on the TSC1-TSC2 complex showed that Akt signaling was unaffected by pH but that the Raf/MEK/ERK pathway was inhibited. Inhibition of MEK with drugs caused only modest mTORC1 inhibition, implying that other unidentified pathways also play major roles. CONCLUSIONS: This study reveals a novel role for the TSC1/TSC2 complex and mTORC1 in sensing variations in ambient pH. As a common feature of low tissue perfusion, low glucose availability and high energy expenditure, acidic pH may serve as a signal for mTORC1 to downregulate energy-consuming anabolic processes such as protein synthesis as an adaptive response to metabolically stressful conditions

    The interaction between practice and performance pressure on the planning and control of fast target directed movement

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    Pressure to perform often results in decrements to both outcome accuracy and the kinematics of motor skills. Furthermore, this pressure-performance relationship is moderated by the amount of accumulated practice or the experience of the performer. However, the interactive effects of performance pressure and practice on the underlying processes of motor skills are far from clear. Movement execution involves both an offline pre-planning process and an online control process. The present experiment aimed to investigate the interaction between pressure and practice on these two motor control processes. Two groups of participants (control and pressure; N = 12 and 12, respectively) practiced a video aiming amplitude task and were transferred to either a non-pressure (control group) or a pressure condition (pressure group) both early and late in practice. Results revealed similar accuracy and movement kinematics between the control and pressure groups at early transfer. However, at late transfer, the introduction of pressure was associated with increased performance compared to control conditions. Analysis of kinematic variability throughout the movement suggested that the performance increase was due to participants adopting strategies to improve movement planning in response to pressure reducing the effectiveness of the online control system

    How the required precision influences the way we intercept a moving object

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    Do people perform a given motor task differently if it is easy than if it is difficult? To find out, we asked subjects to intercept moving virtual targets by tapping on them with their fingers. We examined how their behaviour depended on the required precision. Everything about the task was the same on all trials except the extent to which the fingertip and target had to overlap for the target to be considered hit. The target disappeared with a sound if it was hit and deflected away from the fingertip if it was missed. In separate sessions, the required precision was varied from being quite lenient about the required overlap to being very demanding. Requiring a higher precision obviously decreased the number of targets that were hit, but it did not reduce the variability in where the subjects tapped with respect to the target. Requiring a higher precision reduced the systematic deviations from landing at the target centre and the lag-one autocorrelation in such deviations, presumably because subjects received information about smaller deviations from hitting the target centre. We found no evidence for lasting effects of training with a certain required precision. All the results can be reproduced with a model in which the precision of individual movements is independent of the required precision, and in which feedback associated with missing the target is used to reduce systematic errors. We conclude that people do not approach this motor task differently when it is easy than when it is difficult. © 2013 Springer-Verlag Berlin Heidelberg

    The Political Economy of Taxation: Positive and Normative Analysis when Collective Choice Matters

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    Recovery Time Course in Contractile Function of Fast and Slow Skeletal Muscle after Hindlimb Immobilization

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    Contractile properties were evaluated in rats remobilized after 6 wk of hindlimb casting to evaluate the regenerative capacity of fast and slow skeletal muscles. Contractile parameters were determined in vitro (22ºC) in the type I soleus (SOL), type IIA and IIB extensor digitorum longus (EDL), and the type IIB superficial vastus lateralis (SVL). Immobilization (IM) shortened the SOL isometric twitch duration after which contraction time and half-relaxation time required 4 and 7 days to recover, respectively. In contrast, IM prolonged the twitch in the EDL and SVL and recovery required 14 and 7 days, respectively. Peak tetanic tension (g/cm2) fell in the SOL and EDL with IM and full recovery required 28 days. In this regard, the SVL remained unaltered. Rates of tension development and decline remained essentially unaltered in the fast muscles after IM but fell in the SOL, requiring 14 days to fully recover. Maximal shortening velocity, which had been elevated in all three muscles by IM, recovered rapidly. The present results demonstrate that both fast and slow muscle have the ability to completely recover from 6 weeks of IM
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