1,898 research outputs found

    A Biographical Sketch of John Greenleaf Whittier from The Early Poems of John Greenleaf Whittier

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    Biographical sketch from The Early Poems of John Greenleaf Whittier. Spine title Whittier\u27s Poetical Works. Biographical sketch written by N. H. Dole. Pages ix-xxxii. Portrait of Whittier included.https://digitalcommons.georgefox.edu/quakerbooks/1040/thumbnail.jp

    Correlated Anisotropies in the Cosmic Far-Infrared Background Detected by MIPS/Spitzer: Constraint on the Bias

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    We report the detection of correlated anisotropies in the Cosmic Far-Infrared Background at 160 microns. We measure the power spectrum in the Spitzer/SWIRE Lockman Hole field. It reveals unambiguously a strong excess above cirrus and Poisson contributions, at spatial scales between 5 and 30 arcminutes, interpreted as the signature of infrared galaxy clustering. Using our model of infrared galaxy evolution we derive a linear bias b=1.74 \pm 0.16. It is a factor 2 higher than the bias measured for the local IRAS galaxies. Our model indicates that galaxies dominating the 160 microns correlated anisotropies are at z~1. This implies that infrared galaxies at high redshifts are biased tracers of mass, unlike in the local Universe.Comment: ApJ Letters, in pres

    DEVELOPEMENT AND VALIDATION OF ANALYTICAL METHOD FOR SIMULTANEOUS ESTIMATION OF CILNIDIPINE AND OLMESARTAN MEDOXOMIL IN BULK AND TABLET DOSAGE FORM BY RP-HPLC

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    An economical, precise, rapid and accurate RP HPLC method has been developed for the simultaneous estimation of Olmesartan Medoxomil and Cilnidipine in bulk and tablet dosage form. Separation was carried out on Jasco HPLC system equipped with HiQ sil C18 column (250 × 4.6 mm i.d.) and PDA detector using Methanol: 40 mM Potassium dihydrogen ortho phosphate buffer (90:10 v/v) as the mobile phase.Ortho-phosphoric acid was used to adjust pH to 3.0, and detection was carried out at 254 nm. Results were linear in the range of 5-30 μg/ml for Cilnidipine and 10-50 μg/ml for Olmesartan Medoxomil respectively. The method was successfully applied for the analysis of drugs in pharmaceutical formulation. Results of the analysis were validated statistically and by recovery studies

    Multi-wavelength characterisation of z~2 clustered, dusty star forming galaxies discovered by Planck

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    (abridged) We report the discovery of PHz G95.5-61.6, a complex structure detected in emission in the Planck all-sky survey that corresponds to two over-densities of high-redshift galaxies. This is the first source from the Planck catalogue of high-z candidates that has been completely characterised with follow-up observations from the optical to the sub-millimetre domain. Herschel/SPIRE observations at 250, 350 and 500 microns reveal the existence of five sources producing a 500 microns emission excess that spatially corresponds to the candidate proto-clusters discovered by Planck. Further observations at CFHT in the optical bands (g and i) and in the near infrared (J, H and K_s), plus mid infrared observations with IRAC/Spitzer (at 3.6 and 4.5 microns) confirm that the sub-mm red excess is associated with an over-density of colour-selected galaxies. Follow-up spectroscopy of 13 galaxies with VLT/X-Shooter establishes the existence of two high-z structures: one at z~1.7 (three confirmed member galaxies), the other at z~2.0 (six confirmed members). This double structure is also seen in the photometric redshift analysis of a sample of 127 galaxies located inside a circular region of 1'-radius containing the five Herschel/SPIRE sources, where we found a double-peaked excess of galaxies at z~1.7 and z~2.0 with respect to the surrounding region. These results suggest that PHz G95.5-61.6 corresponds to two accreting nodes, not physically linked to one another, embedded in the large scale structure of the Universe at z~2 and along the same line-of-sight. In conclusion, the data, methods and results illustrated in this pilot project confirm that Planck data can be used to detect the emission from clustered, dusty star forming galaxies at high-z, and, thus, to pierce through the early growth of cluster-scale structures.Comment: 15 pages, 13 figures. Accepted for publication in Astronomy and Astrophysic

    The infrared luminosity function of galaxies at redshifts z=1 and z~2 in the GOODS fields

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    We present the rest-frame 8 micron luminosity function (LF) at redshifts z=1 and ~2, computed from Spitzer 24 micron-selected galaxies in the GOODS fields over an area of 291 sq. arcmin. Using classification criteria based on X-ray data and IRAC colours, we identify the AGN in our sample. The rest-frame 8 micron LF for star-forming galaxies at redshifts z=1 and ~2 have the same shape as at z~0, but with a strong positive luminosity evolution. The number density of star-forming galaxies with log_{10}(nu L_nu(8 micron))>11 increases by a factor >250 from redshift z~0 to 1, and is basically the same at z=1 and ~2. The resulting rest-frame 8 micron luminosity densities associated with star formation at z=1 and ~2 are more than four and two times larger than at z~0, respectively. We also compute the total rest-frame 8 micron LF for star-forming galaxies and AGN at z~2 and show that AGN dominate its bright end, which is well-described by a power-law. Using a new calibration based on Spitzer star-forming galaxies at 0<z<0.6 and validated at higher redshifts through stacking analysis, we compute the bolometric infrared (IR) LF for star-forming galaxies at z=1 and ~2. We find that the respective bolometric IR luminosity densities are (1.2+/-0.2) x 10^9 and (6.6^{+1.2}_{-1.0}) x 10^8 L_sun Mpc^{-3}, in agreement with previous studies within the error bars. At z~2, around 90% of the IR luminosity density associated with star formation is produced by luminous and ultraluminous IR galaxies (LIRG and ULIRG), with the two populations contributing in roughly similar amounts. Finally, we discuss the consistency of our findings with other existing observational results on galaxy evolution.Comment: Accepted for publication in the ApJ. 33 pages, 15 figures. Uses emulateap

    A lensed protocluster candidate at z=7.66z=7.66 identified in JWST observations of the galaxy cluster SMACS0723-7327

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    According to the current paradigm of galaxy formation, the first galaxies have been likely formed within large dark matter haloes. The fragmentation of these massive haloes led to the formation of galaxy protoclusters, which are usually composed of one to a few bright objects, surrounded by numerous fainter (and less massive) galaxies. These early structures could have played a major role in reionising the neutral hydrogen within the first billion years of the Universe; especially, if their number density is significant.Taking advantage of the unprecedented sensitivity reached by the \textit{James Webb Space Telescope (JWST)}, galaxy protoclusters can now be identified and studied in increasing numbers beyond z z\geq\ 6. Characterising their contribution to the UV photon budget could supply new insights into the reionisation process. We analyse the first JWST dataset behind SMACS0723-7327 to search for protoclusters at z6z\geq6, combining the available spectroscopic and photometric data. We then compare our findings with semi-analytical models and simulations. In addition to two bright galaxies (\leq26.5 AB in F277W), separated by \sim11\arcsec and spectroscopically confirmed at zspec=7.66z_{spec}=7.66, we identify 6 additional galaxies with similar colors in a θ20\theta\sim20\arcsec radius around these (corresponding to R6090\sim60-90 kpc in the source plane). Using several methods, we estimate the mass of the dark matter halo of this protocluster, \sim3.3×\times1011^{11}M_{\odot} accounting for magnification, consistent with various predictions. The physical properties of all protocluster members are also in excellent agreement with what has been previously found at lower redshifts: star-formation main sequence and protocluster size. This detection adds to just a few protoclusters currently known in the first billion years of the universe.Comment: 7 pages, 6 Figures. Accepted for publication in A&A Lette

    Some Properties of BSCCO-Ag Added High Temperature Superconductors

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    Simulations of the cosmic infrared and submillimeter background for future large surveys: I. Presentation and first application to Herschel/SPIRE and Planck/HFI

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    The coming Planck and Herschel missions will survey the sky at unprecedented angular scales and sensitivities. Simulations are needed for better interpretating the results of the surveys and for testing new methods of, e.g., source extraction and component separation. We present new simulations of the infrared and submillimeter cosmic background, including the correlation between infrared galaxies. The simulations were used to quantify the source-detection thresholds for Herschel/SPIRE and Planck/HFI, as well as to study the detectability of the cosmic infrared background correlated fluctuations. The simulations are based on an empirical model of IR galaxy evolution. For the correlations, we only included the linear clustering, assuming that infrared galaxies are biased tracers of the dark-matter fluctuation density field. We used the simulations with different bias parameters to predict the confusion noise for Herschel/SPIRE and Planck/HFI and the completeness levels. We also discuss the detectability of the linear clustering in Planck/HFI power spectra, including the foreground and backgrounds components. Simulated maps and catalogs are publicly available online at http://www.ias.u-psud.fr/irgalaxies/simulations.phpComment: A&A, 2008, in pres

    Habitable Climates: The Influence of Eccentricity

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    In the outer regions of the habitable zone, the risk of transitioning into a globally frozen "snowball" state poses a threat to the habitability of planets with the capacity to host water-based life. We use a one-dimensional energy balance climate model (EBM) to examine how obliquity, spin rate, orbital eccentricity, and ocean coverage might influence the onset of such a snowball state. For an exoplanet, these parameters may be strikingly different from the values observed for Earth. Since, for constant semimajor axis, the annual mean stellar irradiation scales with (1-e^2)^(-1/2), one might expect the greatest habitable semimajor axis (for fixed atmospheric composition) to scale as (1-e^2)^(-1/4). We find that this standard ansatz provides a reasonable lower bound on the outer boundary of the habitable zone, but the influence of obliquity and ocean fraction can be profound in the context of planets on eccentric orbits. For planets with eccentricity 0.5, our EBM suggests that the greatest habitable semimajor axis can vary by more than 0.8 AU (78%!) depending on obliquity, with higher obliquity worlds generally more stable against snowball transitions. One might also expect that the long winter at an eccentric planet's apoastron would render it more susceptible to global freezing. Our models suggest that this is not a significant risk for Earth-like planets around Sun-like stars since such planets are buffered by the thermal inertia provided by oceans covering at least 10% of their surface. Since planets on eccentric orbits spend much of their year particularly far from the star, such worlds might turn out to be especially good targets for direct observations with missions such as TPF-Darwin. Nevertheless, the extreme temperature variations achieved on highly eccentric exo-Earths raise questions about the adaptability of life to marginally or transiently habitable conditions.Comment: References added, text and figures updated, accepted by Ap

    Spitzer 70 and 160-micron Observations of the COSMOS Field

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    We present Spitzer 70 and 160 micron observations of the COSMOS Spitzer survey (S-COSMOS). The data processing techniques are discussed for the publicly released products consisting of images and source catalogs. We present accurate 70 and 160 micron source counts of the COSMOS field and find reasonable agreement with measurements in other fields and with model predictions. The previously reported counts for GOODS-North and the extragalactic First Look Survey are updated with the latest calibration, and counts are measured based on the large area SWIRE survey to constrain the bright source counts. We measure an extragalactic confusion noise level of sigma_c = 9.4+/-3.3 mJy (q=5) for the MIPS 160-micron band based on the deep S-COSMOS data and report an updated confusion noise level of sigma_c = 0.35+/-0.15 mJy (q=5) for the MIPS 70-micron band.Comment: Accepted AJ, 15 Aug. 2009. Data available at http://spider.ipac.caltech.edu/staff/frayer/mycosmos/ until released by IRS
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