19,459 research outputs found

    Insulating effectiveness of self-spacing dimpled foil

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    Experimental data are graphed for determining conductive heat losses of multilayer insulation as function of number of foil layers. Foil was 0.0051 cm thick Nb, 1% Zr refractory alloy, dimpled to 0.0254 cm with approximately 28 dimples/sq cm. Heat losses were determined at 0.1 microtorr between 700 and 1089 K

    Direct Marketing of Fresh Produce: Understanding Consumer Purchasing Decisions

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    Consumer/Household Economics, Crop Production/Industries, Marketing, Q13,

    Arkansas Soybean Performance Tests 2018

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    Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

    Shuttle program: OFT ascent/descent ancillary data requirements document

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    Requirements are presented for the ascent/descent (A/D) navigation and attitude-dependent ancillary data products to be generated for the space shuttle orbiter in support of the orbital flight test (OFT) flight test requirements, MPAD guidance and navigation performance assessment, and the mission evaluation team. The A/D ancillary data support for OFT mission evaluation activities is confined to providing postflight position, velocity, attitude, and associated navigation and attitude derived parameters for the Orbiter over particular flight phases and time intervals

    The Impact of baryonic physics on the kinetic Sunyaev-Zel'dovich Effect

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    Poorly understood "baryonic physics" impacts our ability to predict the power spectrum of the kinetic Sunyaev-Zel'dovich (kSZ) effect. We study this in one sample high resolution simulation of galaxy formation and feedback, Illustris. The high resolution of Illustris allows us to probe the kSZ power spectrum on multipoles ℓ=103−3×104\ell =10^3-3\times 10^4. Strong AGN feedback in Illustris nearly wipes out gas fluctuations at k≳1 h Mpc−1k\gtrsim1~h~\rm{Mpc}^{-1} and at late times, likely somewhat under predicting the kSZ power generated at z≲1z\lesssim 1. The post-reionization kSZ power spectrum for Illustris is well-fit by Dℓz<6=1.38[ℓ/3000]0.21 μK2\mathcal{D}^{z<6}_{\ell} = 1.38[\ell/3000]^{0.21}~\mu K^2 over 3000≲ℓ≲100003000\lesssim\ell\lesssim10000, somewhat lower than most other reported values but consistent with the analysis of Shaw et al. Our analysis of the bias of free electrons reveals subtle effects associated with the multi-phase gas physics and stellar fractions that affect even linear scales. In particular there are fewer electrons in biased galaxies, due to gas cooling and star formation, and this leads to an electron bias less than one even at low wavenumbers. The combination of bias and electron fraction that determines the overall suppression is relatively constant, fe2be02∼0.7f_e^2b^2_{e0} \sim 0.7, but more simulations are needed to see if this is Illustris-specific. By separating the kSZ power into different terms, we find at least 6 (10)%6\, (10)\% of the signal at ℓ=3000 (10000)\ell=3000\, (10000) comes from non-Gaussian connected four-point density and velocity correlations, \left_{c}, even without correcting for the Illustris simulation box size. A challenge going forward will be to accurately model long-wave velocity modes simultaneously with Illustris-like high resolution to capture the complexities of galaxy formation and its correlations with large scale flows.Comment: 12 pages, 9 figure, submitted to Ap

    CMBFAST for spatially closed universes

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    We extend the cosmological linear perturbation theory code CMBFAST to closed geometries. This completes the implementation of CMBFAST to all types of geometries and allows the user to perform an unlimited search in the parameter space of models. This will be specially useful for placing confidence limits on cosmological parameters from existing and future data. We discuss some of the technical issues regarding the implementation.Comment: 6 pages, 2 figures, new version of CMBFAST can be found http://www.sns.ias.edu/~matiasz/CMBFAST/cmbfast.htm

    Probing the Primordial Power Spectrum with Cluster Number Counts

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    We investigate how well galaxy cluster number counts can constrain the primordial power spectrum. Measurements of the primary anisotropies in the cosmic microwave background (CMB) may be limited, by the presence of foregrounds from secondary sources, to probing the primordial power spectrum at wave numbers less than about 0.30 h Mpc^{-1}. We break up the primordial power spectrum into a number of nodes and interpolate linearly between each node. This allows us to show that cluster number counts could then extend the constraints on the form of the primordial power spectrum up to wave numbers of about 0.45 h Mpc^{-1}. We estimate combinations of constraints from PLANCK and SPT primary CMB and their respective SZ surveys. We find that their constraining ability is limited by uncertainties in the mass scaling relations. We also estimate the constraint from clusters detected from a SNAP like gravitational lensing survey. As there is an unambiguous and simple relationship between the filtered shear of the lensing survey and the cluster mass, it may be possible to obtain much tighter constraints on the primordial power spectrum in this case.Comment: Clarifications added and a few minor corrections made. Matches version to appear in PR

    The scale of homogeneity in the Las Campanas Redshift Survey

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    We analyse the Las Campanas Redshift Survey using the integrated conditional density (or density of neighbors) in volume-limited subsamples up to unprecedented scales (200 Mpc/hh) in order to determine without ambiguity the behavior of the density field. We find that the survey is well described by a fractal up to 20-30 Mpc/hh, but flattens toward homogeneity at larger scales. Although the data are still insufficient to establish with high significance the expected homogeneous behavior, and therefore to rule out a fractal trend to larger scales, a fit with a CDM-like spectrum with high normalization well represents the data.Comment: 8 pages, 3 figures, accepted on Ap.J. Letter
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