17,691 research outputs found

    Evaluation of nickel-hydrogen battery for space application

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    Results of electrical space qualification tests of nickel-hydrogen battery type HR 23S are presented. The results obtained for the nickel-cadmium battery type VO 23S are similar except that the voltage level and the charge conservation characteristics vary significantly. The electrical and thermal characteristics permit predictions of the following optimal applications: charge coefficient in the order of 1.3 to 1.4 at 20C; charge current density higher than C/10 at 20C; discharge current density from C/10 to C/3 at 20C; maximum discharge temperature: OC; storage temperature: -20C

    Influence of Nd on the magnetic properties of Nd1-xCaxMnO3

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    The role played by the Nd ions in the magnetic properties of Nd0.5Ca0.5MnO3 and Nd0.7Ca0.3MnO3 is studied using static magnetization, neutron diffraction and high frequency (9.4-475GHz) Electron Spin Resonance. We show that the Nd ions are weakly coupled to the Mn ions via ferromagnetic exchange and are responsible for the peculiar ferromagnetic resonance observed in the FM phase of both compounds (ground state below 120K for x=0.3, high field state for x=0.5). We then use ESR to look for magnetic phase separation in the low field, CO phase of Nd0.5Ca0.5MnO3. We show that there is no trace of the FM phase imbedded in the CO phase, contrary to what is observed in La0.5Ca0.5MnO3 or Pr0.5Sr0.5MnO3.Comment: to be published in phys.Rev.B as a Rapid Com

    Long-lived quantum memory with nuclear atomic spins

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    We propose to store non-classical states of light into the macroscopic collective nuclear spin (101810^{18} atoms) of a 3^3He vapor, using metastability exchange collisions. These collisions, commonly used to transfer orientation from the metastable state 23S_12^{3}S\_1 to the ground state state of 3^3He, can also transfer quantum correlations. This gives a possible experimental scheme to map a squeezed vacuum field state onto a nuclear spin state with very long storage times (hours).Comment: 4 page

    Squad management, injury and match performance in a professional soccer team over a Championship-winning season

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    Squad management, injury and physical, tactical and technical match performance were investigated in a professional soccer team across five consecutive league seasons (2008–2013, 190 league games) with specific focus on a championship-winning season (2010/11). For each player, match participation and time-loss injuries were recorded, the latter prospectively diagnosed by the team's physician. Defending and attacking tactical and technical performance indicators investigated included ball possession and possession in opponents' half, passes, forward passes, completed passes and forward passes, crosses and completed crosses, goal attempts and goal attempts on target, successful final third entries, free-kicks and 50/50 duels won/lost. Physical performance measures included total distance and distance covered at high-speeds (≥19.1 km/h). Results showed that during the 2010/11 season, squad utilisation was lowest potentially owing to the observed lower match injury occurrence and working days lost to injury thereby increasing player availability. In 2010/11, the team won both its highest number of points and conceded its lowest number of goals especially over the second half of this season. The team also won its highest number of games directly via a goal from a substitute and scored and conceded a goal first on the highest and lowest number of occasions, respectively. While multivariate analysis of variance (MANOVA) detected a significant difference in some attacking and defensive performance indicators across the five seasons, these were generally not distinguishing factors in 2010/11. Similarly, univariate ANOVAs showed a significant difference in running distances covered across seasons, but the trend was for less activity in 2010/11

    Are aerobic fitness and repeated sprint ability linked to fatigue in professional soccer match-play? A pilot study

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    This investigation examined the association between aerobic fitness and repeated sprint ability and match-related fatigue in 9 professional outfield soccer players. Aerobic fitness using maximal aerobic speed (MAS) was determined via a continuous progressive incremental running test conducted on a motorised treadmill. A repeated sprint ability test (6 successive 6 s sprints separated by 20 s passive recovery) was performed on a non-motorised treadmill to determine mean and best sprint times and a percentage decrement score (%PD). A total of 114 observations of physical performance derived using computerised time motion analyses were collected from 33 matches. Correlations between fitness test and match-play measures were examined for 1) accumulated fatigue: percentage difference between halves for total distance covered per minute, distance run at high-intensities (HIR, actions for 1s duration, >19.1 km/h) per minute, mean recovery time between high-intensity runs, and percentage difference between the distance covered in HIR in the first 5- and 15-minute periods versus the final 5- and 15-minute periods respectively in normal time; and for 2) transient fatigue: percentage difference between the distance covered in HIR in a peak 5-minute period and the subsequent 5-minute period and for the latter compared to the mean for all other 5-minute periods. No significant relationships were observed between MAS and fatigue scores (magnitude of associations: trivial to large). For mean and best sprint times and %PD, the only reported significant correlation (r=0.77, magnitude of association: very large, p<0.05) was between %PD and the % difference across halves for mean recovery time between high-intensity runs (magnitude of other associations: small to large). Criterion measures from tests of aerobic fitness and repeated sprint ability might not accurately depict a player’s capacity to resist fatigue during professional soccer competition

    Metabolic pathways of the wheat (Triticum aestivum) endosperm amyloplast revealed by proteomics

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    <p>Abstract</p> <p>Background</p> <p>By definition, amyloplasts are plastids specialized for starch production. However, a proteomic study of amyloplasts isolated from wheat (<it>Triticum aestivum </it>Butte 86) endosperm at 10 days after anthesis (DPA) detected enzymes from many other metabolic and biosynthetic pathways. To better understand the role of amyloplasts in food production, the data from that study were evaluated in detail and an amyloplast metabolic map was outlined.</p> <p>Results</p> <p>Analysis of 288 proteins detected in an amyloplast preparation predicted that 178 were amyloplast proteins. Criteria included homology with known plastid proteins, prediction of a plastid transit peptide for the wheat gene product or a close homolog, known plastid location of the pathway, and predicted plastid location for other members of the same pathway. Of these, 135 enzymes were arranged into 18 pathways for carbohydrate, lipid, amino acid, nucleic acid and other biosynthetic processes that are critical for grain-fill. Functions of the other proteins are also discussed.</p> <p>Conclusion</p> <p>The pathways outlined in this paper suggest that amyloplasts play a central role in endosperm metabolism. The interacting effects of genetics and environment on starch and protein production may be mediated in part by regulatory mechanisms within this organelle.</p

    Multiplicity of Solutions in Aerodynamics

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    One of the most striking phenomena which accompany the flow of fluids such as air and water about bodies, is that of changes in character. This phenomena is still very little understood. We will first discuss the nature of these changes and then show that pure theory leads to a multiplicity of characters of flow, among which we will endeavor to indicate those bearing some analogy to experimental results
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