38 research outputs found

    Constraints on accelerating universe using ESSENCE and Gold supernovae data combined with other cosmological probes

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    We use recently observed data: the 192 ESSENCE type Ia supernovae (SNe Ia), the 182 Gold SNe Ia, the 3-year WMAP, the SDSS baryon acoustic peak, the X-ray gas mass fraction in clusters and the observational H(z)H(z) data to constrain models of the accelerating universe. Combining the 192 ESSENCE data with the observational H(z)H(z) data to constrain a parameterized deceleration parameter, we obtain the best fit values of transition redshift and current deceleration parameter zT=0.6320.127+0.256z_{T}=0.632^{+0.256}_{-0.127}, q0=0.7880.182+0.182q_{0}=-0.788^{+0.182}_{-0.182}. Furthermore, using Λ\LambdaCDM model and two model-independent equation of state of dark energy, we find that the combined constraint from the 192 ESSENCE data and other four cosmological observations gives smaller values of Ω0m\Omega_{0m} and q0q_{0}, but a larger value of zTz_{T} than the combined constraint from the 182 Gold data with other four observations. Finally, according to the Akaike information criterion it is shown that the recently observed data equally supports three dark energy models: Λ\LambdaCDM, wde(z)=w0w_{de}(z)=w_{0} and wde(z)=w0+w1ln(1+z)w_{de}(z)=w_{0}+w_{1}\ln(1+z).Comment: 18 pages, 8 figure

    The SPTPoL extended cluster survey

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    We describe the observations and resultant galaxy cluster catalog from the 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev-Zel'dovich (SZ) effect and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete follow-up we have confirmed as clusters 244 of 266 candidates at a detection significance ξ ≥ 5 and an additional 204 systems at 4 4 threshold, and 10% of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and we find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness-SZ mass (l - M) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data-a difference significant at the 4σ level-with the relations intersecting at λ = 60. The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses

    CONSUMER PROTECTION, EDUCATION AND INFORMATION: A CONSUMER INCENTIVES PERSPECTIVE

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    Research evidence concerning product characteristics, consumer characteristics and product purchase situations is examined. Assumptions underlying consumer policy strategies directed at enhancing the ability of consumers to protect themselves and those strategies aimed at product quality control are analyzed in light of the evidence. Alternative policy strategies are analyzed for consumer incentives and with respect to product characteristics, consumer characteristics and product purchase situations. Recommendations regarding consumer protection policy strategies and for research concerning alternative policy strategies are provided. Illustrative policy strategies are included. Copyright 1983 by The Policy Studies Organization.

    NMR insights into wasteforms for the vitrification of high-level nuclear waste

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    Magic-angle spinning nuclear magnetic resonance of B-11, Si-29 and Al-27 has been used to study the distribution of nonbridging oxygen atoms (NBO) in an alkali borosilicate glass to which surrogate oxides for high-level radioactive waste have been added. The properties of such glasses are shown to depend on the fraction N (4) of four-coordinated boron atoms (B4) and on the fraction of silicate tetrahedra possessing one NBO, Q(3). The aqueous corrosion rate increases with Q(3) content, as does weight loss due to evaporation from the melt. The activation energy for direct current conduction scales with N-4. Values of N-4 obtained for these glasses deviate from those predicted by the currently accepted model and are strongly affected by the modifier or intermediate nature of the surrogate oxide and also by its effect on the distribution of NBO between the silicate and borate polyhedra
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