18,804 research outputs found

    Examining motivational correlates of mental toughness in Spanish athletes

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    Based on Self Determination and Achievement Goal theories, in this study we tested the relationship between perceptions of coaches’ in- terpersonal styles, athlete’s goal orientations, mental toughness (MT) and future intention of sport practice, as well as self-perception of achievement in sport in a sample of 155 athletes (82 men and 73 women) with a mean age of 22.64 + 3.91 years, from 13 teams who completed a questionnaire with the variables of interest for the study. Results revealed that athlete’s perceptions of autonomy supportive interpersonal style positively predic- ted task orientation, while athlete’s perceptions of controlling interpersonal style positively predicted ego orientation. Additionally, task orientation and self-perception of achievement in sport positively predicted MT, which in turn predicted future intention of sport practice. Results emphasize the importance of having coaches promoting autonomy supportive atmosphe- res to facilitate the development of MT in athletes. Based on Self Determination and Achievement Goal theories, in this study we tested the relationship between perceptions of coaches’ in- terpersonal styles, athlete’s goal orientations, mental toughness (MT) and future intention of sport practice, as well as self-perception of achievement in sport in a sample of 155 athletes (82 men and 73 women) with a mean age of 22.64 + 3.91 years, from 13 teams who completed a questionnaire with the variables of interest for the study. Results revealed that athlete’s perceptions of autonomy supportive interpersonal style positively predic- ted task orientation, while athlete’s perceptions of controlling interpersonal style positively predicted ego orientation. Additionally, task orientation and self-perception of achievement in sport positively predicted MT, which in turn predicted future intention of sport practice. Results emphasize the importance of having coaches promoting autonomy supportive atmosphe- res to facilitate the development of MT in athletes.

    Study and modification of the reactivity of carbon fibers

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    The reactivity to air of polyactylonitrile-based carbon fiber cloth was enhanced by the addition of metals to the cloth. The cloth was oxidized in 54 wt% nitric acid in order to increase the surface area of the cloth and to add carbonyl groups to the surface. Metal addition was then achieved by soaking the cloth in metal acetate solution to effect exchange between the metal carbon and hydrogen on the carbonyl groups. The addition of potassium, sodium, calcium and barium enhanced fiber cloth reactivity to air at 573 K. Extended studies using potassium addition showed that success in enhancing fiber cloth reactivity to air depends on: extent of cloth oxidation in nitric acid, time of exchange in potassium acetate solution and the thoroughness of removing metal acetate from the fiber pore structure following exchange. Cloth reactivity increases essentially linearly with increase in potassium addition via exchange

    Zeros of Rydberg-Rydberg Foster Interactions

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    Rydberg states of atoms are of great current interest for quantum manipulation of mesoscopic samples of atoms. Long-range Rydberg-Rydberg interactions can inhibit multiple excitations of atoms under the appropriate conditions. These interactions are strongest when resonant collisional processes give rise to long-range C_3/R^3 interactions. We show in this paper that even under resonant conditions C_3 often vanishes so that care is required to realize full dipole blockade in micron-sized atom samples.Comment: 10 pages, 4 figures, submitted to J. Phys.

    Structure of protease-cleaved escherichia coliα-2-macroglobulin reveals a putative mechanism of conformational activation for protease entrapment

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    Bacterial -2-macroglobulins have been suggested to function in defence as broad-spectrum inhibitors of host proteases that breach the outer membrane. Here, the X-ray structure of protease-cleaved Escherichia coli -2-macroglobulin is described, which reveals a putative mechanism of activation and conformational change essential for protease inhibition. In this competitive mechanism, protease cleavage of the bait-region domain results in the untethering of an intrinsically disordered region of this domain which disrupts native interdomain interactions that maintain E. coli -2-macroglobulin in the inactivated form. The resulting global conformational change results in entrapment of the protease and activation of the thioester bond that covalently links to the attacking protease. Owing to the similarity in structure and domain architecture of Escherichia coli -2-macroglobulin and human -2-macro­globulin, this protease-activation mechanism is likely to operate across the diverse members of this group

    Oral contraceptives, hormone replacement therapy, thrombophilias and risk of venous thromboembolism: a systematic review The Thrombosis: Risk and Economic Assessment of Thrombophilia Screening (TREATS) Study

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    Combined oral contraceptives,oral hormone replacement therapy and thrombophilias are recognised risk factors for venous thromboembolism in women.The objective of this study was to assess the risk of thromboembolism among women with thrombophilia who are taking oral contraceptives or hormone replacement therapy, conducting a systematic review and metaanalysis. Of 201 studies identified, only nine met the inclusion criteria. Seven studies included pre-menopausal women on oral contraceptives and two studies included peri-menopausal women on hormone replacement therapy. For oral contraceptive use, significant associations of the risk of venous thromboembolism were found in women with factor V Leiden (OR 15.62; 95%CI 8.66 to 28.15); deficiencies of antithrombin (OR 12.60; 95%CI 1.37 to 115.79), protein C (OR 6.33; 95%CI 1.68 to 23.87), or protein S (OR 4.88; 95%CI 1.39 to 17.10), elevated levels of factor VIIIc (OR 8.80; 95%CI 4.13 to 18.75); and factor V Leiden and prothrombin G20210A (OR 7.85; 95%CI 1.65 to 37.41). For hormone replacement therapy, a significant association was found in women with factor V Leiden (OR 13.16; 95%CI 4.28 to 40.47).Although limited by the small number of studies, the findings of this study support the presence of interaction between thrombophilia and venous thromboembolism among women taking oral contraceptives. However, further studies are required to establish with greater confidence the associations of these, and other, thrombophilias with venous thromboembolism among hormone users

    Individual-specific changes in the human gut microbiota after challenge with enterotoxigenic Escherichia coli and subsequent ciprofloxacin treatment

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    Acknowledgements The authors wish to thank Mark Stares, Richard Rance, and other members of the Wellcome Trust Sanger Institute’s 454 sequencing team for generating the 16S rRNA gene data. Lili Fox Vélez provided editorial support. Funding IA, JNP, and MP were partly supported by the NIH, grants R01-AI-100947 to MP, and R21-GM-107683 to Matthias Chung, subcontract to MP. JNP was partly supported by an NSF graduate fellowship number DGE750616. IA, JNP, BRL, OCS and MP were supported in part by the Bill and Melinda Gates Foundation, award number 42917 to OCS. JP and AWW received core funding support from The Wellcome Trust (grant number 098051). AWW, and the Rowett Institute of Nutrition and Health, University of Aberdeen, receive core funding support from the Scottish Government Rural and Environmental Science and Analysis Service (RESAS).Peer reviewedPublisher PD

    Design of Pre-Dumping Ring Spin Rotator with a Possibility of Helicity Switching for Polarized Positrons at the ILC

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    The use of polarized beams enhance the possibility of the precision measurements at the International Linear Collider (ILC). In order to preserve the degree of polarization during beam transport spin rotators are included in the current TDR ILC Lattice. In this report some advantages of using a combined spin rotator/spin flipper are discussed. A few possible lattice designs of spin flipper developed at DESY in 2012 are presented.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 201

    Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6

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    We report an experimental and computational study of magnetic and electronic properties of the layered Ru(V) oxide SrRu2O6 (hexagonal, P-3 1m), which shows antiferromagnetic order with a N\'eel temperature of 563(2) K, among the highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers. Electrical transport measurements using focused ion beam induced deposited contacts on a micron-scale crystallite as a function of temperature show p-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure and Monte Carlo simulations reveals how strong intralayer as well as weaker interlayer interactions are a defining feature of the high temperature magnetic order in the material.Comment: Physical Review B 2015 accepted for publicatio

    T4-induced RNA ligase joins single-stranded oligoribonucleotides.

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