1,066 research outputs found

    Innovative Technology for High Performance and Mass Participation Sport

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    The chapter analyzes technological innovations used in high-level sport and how mass participants have and will benefit from these advancements. The authors discuss progressive practices of different successful sporting nations. The chapter debriefs high-performance facility development and utilization practices, as well as examples of modern equipment and technology being applied in multiple high-performance athlete service areas, such as general fitness, sport-specific training, restoration, nutrition, medicine, and psychology. This section also emphasizes examples of national and local high-performance technology practices for enhancing mass participation, such as evolving networks of comprehensive multisport training centers available for nurturing every possible age and socioeconomic group. Finally, suggestions are made to provide communities, in partnership with universities or local military installations, with recreation and sport technologies which are free or affordable for all, including instructions enabling everyone to utilize and enjoy the new technologies

    C-type related order in the defective fluorites La2Ce2O7 and Nd2Ce2O7 studied by neutron scattering and ab initio MD simulations

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    This work presents a structural investigation of La2-xNdxCe2O7 (x = 0.0, 0.5, 1.0, 1.5, 2.0) using X-ray powder diffraction and total scattering neutron powder diffraction, analysed using Rietveld and the reverse Monte Carlo method (RMC). Ab initio molecular dynamics (MD) modelling is also performed for further investigations of the local order. The main intensities in the neutron diffraction data for the La2-xNdxCe2O7 series correspond to the fluorite structure. However, additional C-type superlattice peaks are visible for x > 0 and increase in intensity with increasing x. The Nd-containing compositions (x > 0) are best fitted with Rietveld analysis by using a combination of oxygen deficient fluorite and oxygen excess C-type structures. No indications of cation order are found in the RMC or Rietveld analysis, and the absence of cation order is supported by the MD modelling. We argue that the superlattice peaks originate from oxygen vacancy ordering and associated shift in the cation position away from the ideal fluorite site similar to that in the C-type structure, which is seen from the Rietveld refinements and the observed ordering in the MD modelling. The vacancies favour alignments in the , and especially the direction. Moreover, we find that such ordering might also be found to a small extent in La2Ce2O7, explaining the discernible modulated background between the fluorite peaks. The observed overlap of the main Bragg peaks between the fluorite and C-type phase supports the co-existence of vacancy ordered and more disordered domains. This is further supported by the observed similarity of the radial distribution functions as modelled with MD. The increase in long range oxygen vacancy order with increasing Nd-content in La2-xNdxCe2O7 corresponds well with the lower oxide ion conductivity in Nd2Ce2O7 compared to La2Ce2O7 reported earlier

    Galaxy And Mass Assembly (GAMA) : refining the local galaxy merger rate using morphological information

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    KRVS acknowledges the Science and Technology Facilities Council (STFC) for providing funding for this project, as well as the Government of Catalonia for a research travel grant (ref. 2010 BE-00268) to begin this project at the University of Nottingham. PN acknowledges the support of the Royal Society through the award of a University Research Fellowship and the European Research Council, through receipt of a Starting Grant (DEGAS-259586).We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass-dependent merger fraction and merger rate using galaxy pairs and the CAS (concentration, asymmetry, and smoothness) structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to M* = 108 M⊙ with mass ratios of 4:1) the lower mass companion becomes highly asymmetric, whereas the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass-dependent major merger fraction is fairly constant at ∼1.3–2 per cent within 109.5 < M* < 1011.5 M⊙, and increases to ∼4 per cent at lower masses. When the observability time-scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total comoving volume major merger rate over the range 108.0 < M* < 1011.5 M⊙ is (1.2 ± 0.5) × 10−3 h370 Mpc−3 Gyr−1.Publisher PDFPeer reviewe

    Crystal structure and proton conductivity of BaSn0.6Sc0.4O3-delta: insights from neutron powder diffraction and solid-state NMR spectroscopy

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    The solid-state synthesis and structural characterisation of perovskite BaSn(1–x)Sc(x)O(3–δ) (x = 0.0, 0.1, 0.2, 0.3, 0.4) and its corresponding hydrated ceramics are reported. Powder and neutron X-ray diffractions reveal the presence of cubic perovskites (space group Pm3m) with an increasing cell parameter as a function of scandium concentration along with some indication of phase segregation. (119)Sn and (45)Sc solid-state NMR spectroscopy data highlight the existence of oxygen vacancies in the dry materials, and their filling upon hydrothermal treatment with D(2)O. It also indicates that the Sn(4+) and Sc(3+) local distribution at the B-site of the perovskite is inhomogeneous and suggests that the oxygen vacancies are located in the scandium dopant coordination shell at low concentrations (x ≤ 0.2) and in the tin coordination shell at high concentrations (x ≥ 0.3). (17)O NMR spectra on (17)O enriched BaSn(1–x)Sc(x)O(3–δ) materials show the existence of Sn–O–Sn, Sn–O–Sc and Sc–O–Sc bridging oxygen environments. A further room temperature neutron powder diffraction study on deuterated BaSn(0.6)Sc(0.4)O(3–δ) refines the deuteron position at the 24k crystallographic site (x, y, 0) with x = 0.579(3) and y = 0.217(3) which leads to an O–D bond distance of 0.96(1) Å and suggests tilting of the proton towards the next nearest oxygen. Proton conduction was found to dominate in wet argon below 700 °C with total conductivity values in the range 1.8 × 10(–4) to 1.1 × 10(–3) S cm(–1) between 300 and 600 °C. Electron holes govern the conduction process in dry oxidizing conditions, whilst in wet oxygen they compete with protonic defects leading to a wide mixed conduction region in the 200 to 600 °C temperature region, and a suppression of the conductivity at higher temperature

    Halo Occupation Distribution Modeling of Green Valley Galaxies

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    We present a clustering analysis of near ultraviolet (NUV) - optical color selected luminosity bin samples of green valley galaxies. These galaxy samples are constructed by matching the Sloan Digital Sky Survey Data Release 7 with the latest Galaxy Evolution Explorer source catalog which provides NUV photometry. We present cross-correlation function measurements and determine the halo occupation distribution of these transitional galaxies using a new multiple tracer analysis technique. We extend the halo-occupation formalism to model the cross-correlation function between a galaxy sample of interest and multiple tracer populations simultaneously. This method can be applied to commonly used luminosity threshold samples as well as to color and luminosity bin selected galaxy samples, and improves the accuracy of clustering analyses for sparse galaxy populations. We confirm the previously observed trend that red galaxies reside in more massive halos and are more likely to be satellite galaxies than average galaxies of similar luminosity. While the change in central galaxy host mass as a function of color is only weakly constrained, the satellite fraction and characteristic halo masses of green satellite galaxies are found to be intermediate between those of blue and red satellite galaxies.Comment: matches MNRAS accepted version; minor revisions, results unchange

    Autocorrelations of stellar light and mass at z~0 and ~1: From SDSS to DEEP2

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    We present measurements of projected autocorrelation functions w_p(r_p) for the stellar mass of galaxies and for their light in the U, B and V bands, using data from the third data release of the DEEP2 Galaxy Redshift Survey and the final data release of the Sloan Digital Sky Survey (SDSS). We investigate the clustering bias of stellar mass and light by comparing these to projected autocorrelations of dark matter estimated from the Millennium Simulations (MS) at z=1 and 0.07, the median redshifts of our galaxy samples. All of the autocorrelation and bias functions show systematic trends with spatial scale and waveband which are impressively similar at the two redshifts. This shows that the well-established environmental dependence of stellar populations in the local Universe is already in place at z=1. The recent MS-based galaxy formation simulation of Guo et al. (2011) reproduces the scale-dependent clustering of luminosity to an accuracy better than 30% in all bands and at both redshifts, but substantially overpredicts mass autocorrelations at separations below about 2 Mpc. Further comparison of the shapes of our stellar mass bias functions with those predicted by the model suggests that both the SDSS and DEEP2 data prefer a fluctuation amplitude of sigma_8 0.8 rather than the sigma_8=0.9 assumed by the MS.Comment: 10 pages, 4 figures, accepted for publication in Monthly Notices, minor revisions in tex

    Galaxy And Mass Assembly (GAMA) : stellar mass functions by Hubble type

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    This work was supported by the Austrian Science Foundation FWF under grant P23946. AWG was supported under the Australian Research Council's funding scheme FT110100263.We present an estimate of the galaxy stellar mass function and its division by morphological type in the local (0.025 < z < 0.06) Universe. Adopting robust morphological classifications as previously presented (Kelvin et al.) for a sample of 3727 galaxies taken from the Galaxy And Mass Assembly survey, we define a local volume and stellar mass limited sub-sample of 2711 galaxies to a lower stellar mass limit of M = 109.0 MΘ. We confirm that the galaxy stellar mass function is well described by a double-Schechter function given by Μ* = 1010.64 MΘ, α1 = 0.43, φ1* = 4.18 dex-1 Mpc-3, α2 = −1.50 and φ2* = 0.74 dex-1 Mpc-3. The constituent morphological-type stellar mass functions are well sampled above our lower stellar mass limit, excepting the faint little blue spheroid population of galaxies. We find approximately 71-4+3 per cent of the stellar mass in the local Universe is found within spheroid-dominated galaxies; ellipticals and S0-Sas. The remaining 29-3+4 per cent falls predominantly within late-type disc-dominated systems, Sab-Scds and Sd-Irrs. Adopting reasonable bulge-to-total ratios implies that approximately half the stellar mass today resides in spheroidal structures, and half in disc structures. Within this local sample, we find approximate stellar mass proportions for E : S0-Sa : Sab-Scd : Sd-Irr of 34 : 37 : 24 :5.Publisher PDFPeer reviewe

    The UV-Optical Color Dependence of Galaxy Clustering in the Local Universe

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    We measure the UV-optical color dependence of galaxy clustering in the local universe. Using the clean separation of the red and blue sequences made possible by the NUV - r color-magnitude diagram, we segregate the galaxies into red, blue and intermediate "green" classes. We explore the clustering as a function of this segregation by removing the dependence on luminosity and by excluding edge-on galaxies as a means of a non-model dependent veto of highly extincted galaxies. We find that \xi (r_p, \pi) for both red and green galaxies shows strong redshift space distortion on small scales -- the "finger-of-God" effect, with green galaxies having a lower amplitude than is seen for the red sequence, and the blue sequence showing almost no distortion. On large scales, \xi (r_p, \pi) for all three samples show the effect of large-scale streaming from coherent infall. On scales 1 Mpc/h < r_p < 10 Mpc/h, the projected auto-correlation function w_p(r_p) for red and green galaxies fits a power-law with slope \gamma ~ 1.93 and amplitude r_0 ~ 7.5 and 5.3, compared with \gamma ~ 1.75 and r_0 ~ 3.9 Mpc/h for blue sequence galaxies. Compared to the clustering of a fiducial L* galaxy, the red, green, and blue have a relative bias of 1.5, 1.1, and 0.9 respectively. The w_p(r_p) for blue galaxies display an increase in convexity at ~ 1 Mpc/h, with an excess of large scale clustering. Our results suggest that the majority of blue galaxies are likely central galaxies in less massive halos, while red and green galaxies have larger satellite fractions, and preferentially reside in virialized structures. If blue sequence galaxies migrate to the red sequence via processes like mergers or quenching that take them through the green valley, such a transformation may be accompanied by a change in environment in addition to any change in luminosity and color.Comment: accepted by MNRA

    Theory of Star Formation

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    We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating overdensities to initiate gravitational contraction or collapse, and countering the effects of gravity in these overdense regions. The key dynamical processes involved in star formation -- turbulence, magnetic fields, and self-gravity -- are highly nonlinear and multidimensional. Physical arguments are used to identify and explain the features and scalings involved in star formation, and results from numerical simulations are used to quantify these effects. We divide star formation into large-scale and small-scale regimes and review each in turn. Large scales range from galaxies to giant molecular clouds (GMCs) and their substructures. Important problems include how GMCs form and evolve, what determines the star formation rate (SFR), and what determines the initial mass function (IMF). Small scales range from dense cores to the protostellar systems they beget. We discuss formation of both low- and high-mass stars, including ongoing accretion. The development of winds and outflows is increasingly well understood, as are the mechanisms governing angular momentum transport in disks. Although outstanding questions remain, the framework is now in place to build a comprehensive theory of star formation that will be tested by the next generation of telescopes.Comment: 120 pages, to appear in ARAA. No changes from v1 text; permission statement adde

    Galaxy and mass assembly (GAMA): refining the local galaxy merger rate using morphological information

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    We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass dependent merger fraction and merger rate using galaxy pairs and the CAS structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies, and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to M∗=108M⊙M_{*} = 10^{8}M_{\odot} with mass ratios of 4:1) the lower mass companion becomes highly asymmetric, while the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass dependent major merger fraction is fairly constant at ∼1.3−2%\sim1.3-2\% between 109.5<M∗<1011.5M⊙10^{9.5}<M_{*}<10^{11.5} M_{\odot}, and increases to ∼4%\sim4\% at lower masses. When the observability time scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total co-moving volume major merger rate over the range 108.0<M∗<1011.5M⊙10^{8.0}<M_{*}<10^{11.5} M_{\odot} is (1.2±0.5)×10−3(1.2 \pm 0.5) \times 10^{-3} h703h^{3}_{70} Mpc−3^{-3} Gyr−1^{-1}
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