163 research outputs found

    Time interval moderates the relationship between psyching-up and actual sprint performance

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    This study attempted to test whether the strongest effect of psyching-up (PU) strategy on actual sprint performance can be observed when the strategy is used immediately (or almost) before performance compared with when there is a delay between PU and performance. To do so, 16 male sprinters (age, 20.6 ± 1.3 years; body mass, 77.5 ± 7.1 kg; height, 180.8 ± 5.6 cm) were enrolled in a counterbalanced experimental design in which participants were randomly assigned to 10 sessions (2 [Experimental Condition: imagery vs. distraction] × 5 [Time Intervals: no interval, 1 minute, 2 minutes, 3 minutes, and 5 minutes]). Before performing the experimental tasks, participants rated: (a) the Hooper index, (b) their degree of self-confidence, and (c) after the completion of the experimental test; they rated their perceived effort. Findings showed that the imagery significantly improved sprint performance. Specifically, the imagery enhanced performance on the phase of acceleration (0-10 m) and on the overall sprint (0-30 m) when used immediately before performance and at 1- and 2-minute intervals but not for 3- and 5-minute intervals. These findings support the hypothesis that the potential effect of the PU strategy on performance vanishes over time. The pre-experimental task Hooper and self-efficacy indexes did not change across the 10 experimental sessions, reinforcing the view that the observed performance changes were directly caused by the experimental manipulation and not through any altered status of the athletes (self-efficacy, fatigue/recovery, and stress). The potential mechanisms underlying such a process and practical applications are discussed

    Development of a TE011 Cavity for Thin-Films Study

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    Bulk niobium cavities have almost reached their maximum performances. Maximum accelerating gradient field is above 35-40 MV/m for a multi-cells cavity at 1.8 Kelvin and it achieves 25-30 MV/m with high reliability. The question of increasing the accelerating gradient in a significant way is running regarding the huge amount of units required for new projects (16000 units for ILC). A promising solution is to use thin films of new materials deposited on copper or niobium. In order to investigate the behaviour of these materials for the accelerating cavities, we have developed a dedicated setup based on thermometric method and a TE011 cavity. We present here the design study of the setup and the expected sensitivity of the method for the surface measurement of materials properties under RF fields

    Radiation Hardness Tests Of Piezoelectric Actuators With Fast Neutrons At Liquid Helium Temperature

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    Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators (~24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: ~20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T~4.2 K), was proposed for the working package WP#8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orléans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35”A) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose (~20%): a neutrons fluence of more than 1014 n/cm2 is achieved in ~20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T~4.2 K. This new apparatus allows on-line automatic measurements of actuators characteristics and the cryogenic parameters. Further, the test-cell and actuators are equipped with high purity Ni foils for measuring the total neutrons dose by an activation method. In this report, the details of the irradiation test facility will be described then the experimental data will be analyzed and discussed

    Seasonal variation of plasma testosterone levels in Algerian male Arabia goats

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    The aim of the present work was to evaluate the general monthly averages of the testosterone hormone and the influence of  season and photoperiod on plasma testosterone levels in Arabia bucks of Algeria. Testosterone concentrations were determined throughout one year in blood samples collected every fortnight of the month from nine males of Arabia goat breeds, fed a constant diet, maintained without interactions with female goat. Plasma testosterone level was measured by radioimmunoassay. Analyses performed show that the monthly averages of the testosterone hormone vary during the year; higher levels were recorded during August (T=8.57±6.72, P=0.00***) however, bucks displayed the same change tendency during the same period (P=0.79). Plasma testosterone concentrations vary significantly between seasons (P=0.00***) being higher during autumn (6.15±3.81ng/ml) compared with spring (0.90 ± 1.27ng/ml) when hormone synthesis reaches its lowest levels. In conclusion, Arabia bucks of Algeria displayed a clear seasonality of plasma testosterone concentration with very low levels in winter and spring (from January to May) and high levels in summer and autumn (from July to November).Keywords: Arabia bucks, testosterone, season, photoperiod

    Electromechanical, Thermal Properties And Radiation Hardness Tests Of Piezoelectric Actuators At Low Temperature

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    IPN Orsay participates, in the frame of the CARE project activities supported by EU, to the development of a fast cold tuning system for SRF cavities. The main task of IPN is the full characterization of piezoelectric actuators at low temperature T, and the study of their behaviour when subjected to fast neutrons radiation at T=4.2 K. In order to compare the performance of various industrial piezoelectric actuators, a new apparatus was developed and successfully used for measuring their electromechanical and thermal properties for T in the range 1.8 K-300 K. Different parameters were investigated as function of T: piezoelectric constant, dielectric and thermal properties including heating ΔT due to dielectric losses vs. modulating voltage Vmod and frequency f. We observed a decrease of the maximum displacement ΔX of the actuators tested from ΔX ~40ÎŒm @ 300K down to 1.8ÎŒm-3.5 ÎŒm @ 1.8K, depending on both material and fabrication process of the piezostacks. Besides, both material and fabrication process have a strong influence on the shape of the characteristics ΔX vs. T dependence. Finally a dedicated facility located at CERI institute (OrlĂ©ans, France) for radiation hardness tests of actuators with fast neutrons at T=4.2 K was developed and the first beam tests results are summarized

    Cell entry of a host targeting protein of oomycetes requires gp96

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    This work is supported by the [European Community’s] Seventh Framework Programme [FP7/2007–2013] under grant agreement no. [238550] (L.L., J.D.-U., C.J.S., P.v.W.); BBSRC [BBE007120/1, BB/J018333/1 and BB/G012075/1] (F.T., I.d.B., C.J.S., S.W., P.v.W.); Newton Global Partnership Award [BB/N005058/1] (F.T., P.v.W.), the University of Aberdeen (A.D.T., T.R., C.J.S., P.v.W.) and Deutsche Forschungsgemeinschaft [CRC1093] (P.B., T.S.). We would like to acknowledge the Ministry of Higher Education Malaysia for funding INA. We would like to thank Brian Haas for his bioinformatics support. We would like to acknowledge Neil Gow and Johannes van den Boom for critical reading of the manuscript. We would like to acknowledge Svetlana Rezinciuc for technical help with pH-studies.Peer reviewedPublisher PD
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