4,185 research outputs found

    Extreme ultraviolet and X-ray spectroheliograph for OSO-H

    Get PDF
    A complex scientific instrument was designed, fabricated, tested, and calibrated for launch onboard OSO-H. This instrument consisted of four spectroheliographs and an X-ray polarimeter. The instrument is designed to study solar radiation at selected wavelengths in the X-ray and the extreme ultraviolet ranges, make observations at the H-alpha wavelength, and measure the degree of polarization of X-ray emissions

    Cosmic Microwave Background Anisotropy Window Functions Revisited

    Get PDF
    The primary results of most observations of cosmic microwave background (CMB) anisotropy are estimates of the angular power spectrum averaged through some broad band, called band-powers. These estimates are in turn what are used to produce constraints on cosmological parameters due to all CMB observations. Essential to this estimation of cosmological parameters is the calculation of the expected band-power for a given experiment, given a theoretical power spectrum. Here we derive the "band power" window function which should be used for this calculation, and point out that it is not equivalent to the window function used to calculate the variance. This important distinction has been absent from much of the literature: the variance window function is often used as the band-power window function. We discuss the validity of this assumed equivalence, the role of window functions for experiments that constrain the power in {\it multiple} bands, and summarize a prescription for reporting experimental results. The analysis methods detailed here are applied in a companion paper to three years of data from the Medium Scale Anisotropy Measurement.Comment: 5 pages, 1 included .eps figure, PRD in press---final published versio

    A new approach to the investigation of allergenic respirable particles using a modified Anderson Impactor

    Full text link
    Pollen allergens have been shown to occur in fine particles much smaller than pollen grains. As such allergenic particles have a high probability of entering the lower human airways, it is important to further investigate their origin and their biological and immunological properties. Accordingly, we have modified the particle collection surface of an Andersen Impactor using adhesive coated microscope slides to enable identification by high resolution microscopic analysis and immunodetection of allergenic particulates.<br /

    On superconducting and magnetic properties of iron-oxypnictides

    Full text link
    Pairing symmetry in oxypnictides, a new family of multiband high-Tc superconductors, is partially imposed by the positions of multiple Fermi pockets, which itself can give rise to new order parameters, such as s+,- states or the state of dx^2-y^2 symmetry. Other pairing states may appear on small pockets for long range interactions, but they are expected to be sensitive to defects. We identify the competing antiferromagnetic order with the triplet exciton transition in the semi- metallic background and discuss whether its coexistence with superconductivity explains the doping dependence of Tc.Comment: Fig1b replace

    Effects of zinc supplementation on cognitive function in healthy middle-aged and older adults: the ZENITH study

    Get PDF
    A randomised double-blind placebo-controlled design was employed to investigate the effects of Zn supplementation on cognitive function in 387 healthy adults aged 55ā€“87 years. Several measures of visual memory, working memory, attention and reaction time were obtained using the Cambridge Automated Neuropsychological Test Battery at baseline and then after 3 and 6 months of 0 (placebo), 15 or 30 mg Zn/d. Younger adults (70 years), and performance improved with practice on some measures. For two out of eight dependent variables, there were significant interactions indicating a beneficial effect (at 3 months only) of both 15 and 30 mg/d on one measure of spatial working memory and a detrimental effect of 15 mg/d on one measure of attention. Further work is required to establish whether these findings generalise to older adults in poorer mental and physical health and with less adequate Zn intake and status than the present sample

    CMB Lensing Reconstruction on the Full Sky

    Get PDF
    Gravitational lensing of the microwave background by the intervening dark matter mainly arises from large-angle fluctuations in the projected gravitational potential and hence offers a unique opportunity to study the physics of the dark sector at large scales. Studies with surveys that cover greater than a percent of the sky will require techniques that incorporate the curvature of the sky. We lay the groundwork for these studies by deriving the full sky minimum variance quadratic estimators of the lensing potential from the CMB temperature and polarization fields. We also present a general technique for constructing these estimators, with harmonic space convolutions replaced by real space products, that is appropriate for both the full sky limit and the flat sky approximation. This also extends previous treatments to include estimators involving the temperature-polarization cross-correlation and should be useful for next generation experiments in which most of the additional information from polarization comes from this channel due to sensitivity limitations.Comment: Accepted for publication in Phys. Rev. D; typos correcte

    Prenylated p-Hydroxyacetophenone Derivatives from the Giant Senecio johnstonii

    Full text link
    The extract of the aerial parts of S. johnstonii afforded five known prenylated p-hydroxyacetophenone derivatives, scopoletin and 5-pentadecyl resorcinol together with the tridecyl derivative. The chemotaxonomic situation is discussed briefly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28519/1/0000316.pd

    Exploring Large-scale Structure with Billions of Galaxies

    Full text link
    We consider cosmological applications of galaxy number density correlations to be inferred from future deep and wide multi-band optical surveys. We mostly focus on very large scales as a probe of possible features in the primordial power spectrum. We find the proposed survey of the Large Synoptic Survey Telescope may be competitive with future all-sky CMB experiments over a broad range of scales. On very large scales the inferred power spectrum is robust to photometric redshift errors, and, given a sufficient number density of galaxies, to angular variations in dust extinction and photometric calibration errors. We also consider other applications, such as constraining dark energy with the two CMB-calibrated standard rulers in the matter power spectrum, and controlling the effect of photometric redshift errors to facilitate the interpretation of cosmic shear data. We find that deep photometric surveys over wide area can provide constraints that are competitive with spectroscopic surveys in small volumes.Comment: 11 pages, 7 figures, ApJ accepted, references added, expanded discussion in Sec. 3.
    • ā€¦
    corecore