1,702 research outputs found

    The Mean and Scatter of the Velocity Dispersion-Optical Richness Relation for maxBCG Galaxy Clusters

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    The distribution of galaxies in position and velocity around the centers of galaxy clusters encodes important information about cluster mass and structure. Using the maxBCG galaxy cluster catalog identified from imaging data obtained in the Sloan Digital Sky Survey, we study the BCG-galaxy velocity correlation function. By modeling its non-Gaussianity, we measure the mean and scatter in velocity dispersion at fixed richness. The mean velocity dispersion increases from 202+/-10 km/s for small groups to more than 854+/-102 km/s for large clusters. We show the scatter to be at most 40.5+/-3.5%, declining to 14.9+/-9.4% in the richest bins. We test our methods in the C4 cluster catalog, a spectroscopic cluster catalog produced from the Sloan Digital Sky Survey DR2 spectroscopic sample, and in mock galaxy catalogs constructed from N-body simulations. Our methods are robust, measuring the scatter to well within one-sigma of the true value, and the mean to within 10%, in the mock catalogs. By convolving the scatter in velocity dispersion at fixed richness with the observed richness space density function, we measure the velocity dispersion function of the maxBCG galaxy clusters. Although velocity dispersion and richness do not form a true mass-observable relation, the relationship between velocity dispersion and mass is theoretically well characterized and has low scatter. Thus our results provide a key link between theory and observations up to the velocity bias between dark matter and galaxies.Comment: 25 pages, 15 figures, 2 tables, published in Ap

    Let us ignore the most important feature of the book

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    First student printing, Edwin Grabhorn on The Book, 1944-5https://repository.wellesley.edu/bookartsephemera/1001/thumbnail.jp

    Estimates of in situ Larval Development Time for the Lobster, Homarus Americanus

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    Larval development time is a critical factor in assessing the potential for larval transport, mortality. and subsequently, the connectivity of marine populations through larval exchange. Most estimates of larval duration are based on laboratory studies and may not reflect development times in nature. For larvae of the American lobster (Homarus americanus), temperature-dependent development times have been established in previous laboratory studies. Here, we used the timing of seasonal abundance curves for newly hatched larvae (stage 1) and the final plankonic instar (postlarva), coupled with a model of temperature-dependent development to assess development time in the field. We were unable to reproduce the timing of the seasonal abundance curves using laboratory development rates in our model. Our results suggest that larval development in situ may be twice as fast as reported laboratory rates. This will result in reduced estimates of larval transport potential, and increased estimates of instantaneous mortality rate and production

    Daya Terima Dan Kadar Betakaroten Donat Substitusi Labu Kuning

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    Vitamin A defi ciency in Indonesia is still unresolved, especially in children. Pumpkin is a type of tubers and a local food product that contains high beta-carotene. It is also potential to be used as a substitution for snacks which favored by children such as donuts. The purpose of this study was to determine the acceptability and beta-carotene level of pumpkin donut substitution. This research was true experimental for product development and quasi experimental for acceptability with a completely randomized design, 6 repetitions on one control formula (F0) and 3 modifi cation formula (F1, F2, F3) with additional of pumpkin. Panelist consists of 4 people as limited panelists and 30 people as non trained panelists. The difference of acceptability was analyze using Friedman test and continued with Wilcoxon Signed Rank Test if it shows a signifi cant difference. The level of beta-carotene was analyze using spectrophotometer. The result of this study showed the best acceptability found in formula 3 (with 40% addition of pumpkin) with an average value of 2,28 and beta-carotene level of was 0,139 ppms. Formula 3 donut have a good acceptability and also contains higherbeta-carotene than commercial donuts, so it is potential as an alternative healthy snack for schoolchildren

    Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation

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    We interpret and model the statistical weak lensing measurements around 130,000 groups and clusters of galaxies in the Sloan Digital Sky Survey presented by Sheldon et al. 2007 (Paper I). We present non-parametric inversions of the 2D shear profiles to the mean 3D cluster density and mass profiles in bins of both optical richness and cluster i-band luminosity. We correct the inferred 3D profiles for systematic effects, including non-linear shear and the fact that cluster halos are not all precisely centered on their brightest galaxies. We also model the measured cluster shear profile as a sum of contributions from the brightest central galaxy, the cluster dark matter halo, and neighboring halos. We infer the relations between mean cluster virial mass and optical richness and luminosity over two orders of magnitude in cluster mass; the virial mass at fixed richness or luminosity is determined with a precision of 13% including both statistical and systematic errors. We also constrain the halo concentration parameter and halo bias as a function of cluster mass; both are in good agreement with predictions of LCDM models. The methods employed here will be applicable to deeper, wide-area optical surveys that aim to constrain the nature of the dark energy, such as the Dark Energy Survey, the Large Synoptic Survey Telescope and space-based surveys

    Proceedings of the North American Blueberry Research and Extension Workers Meeting, 2018 Orono, Maine

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    The 2018, the North American Blueberry Research and Extension Workers (NABREW) Conference took place August 12-15 at the Wells Conference Center at the University of Maine in Orono. The meeting was conducted by the University of Maine Cooperative Extension, and a welcome was provided by the president of the University of Maine and UMM, Dr. Joan Ferrini-Mundy. This is the second time that this national conference has been held in Maine; the first was in 1966. This year more than 74 participants from 13 states and four other countries - Norway, Canada, Mexico and New Zealand - attended the conference

    Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82

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    We present the first weak lensing calibration of μ\mu_{\star}, a new galaxy cluster mass proxy corresponding to the total stellar mass of red and blue members, in two cluster samples selected from the SDSS Stripe 82 data: 230 redMaPPer clusters at redshift 0.1z<0.330.1\leq z<0.33 and 136 Voronoi Tessellation (VT) clusters at 0.1z<0.60.1 \leq z < 0.6. We use the CS82 shear catalog and stack the clusters in μ\mu_{\star} bins to measure a mass-observable power law relation. For redMaPPer clusters we obtain M0=(1.77±0.36)×1014h1MM_0 = (1.77 \pm 0.36) \times 10^{14}h^{-1} M_{\odot}, α=1.74±0.62\alpha = 1.74 \pm 0.62. For VT clusters, we find M0=(4.31±0.89)×1014h1MM_0 = (4.31 \pm 0.89) \times 10^{14}h^{-1} M_{\odot}, α=0.59±0.54\alpha = 0.59 \pm 0.54 and M0=(3.67±0.56)×1014h1MM_0 = (3.67 \pm 0.56) \times 10^{14}h^{-1} M_{\odot}, α=0.68±0.49\alpha = 0.68 \pm 0.49 for a low and a high redshift bin, respectively. Our results are consistent, internally and with the literature, indicating that our method can be applied to any cluster finding algorithm. In particular, we recommend that μ\mu_{\star} be used as the mass proxy for VT clusters. Catalogs including μ\mu_{\star} measurements will enable its use in studies of galaxy evolution in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio
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