117 research outputs found

    Cosmic Microwave Background Dipole induced by double inflation

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    The observed CMBR dipole is generally interpreted as the consequence of the peculiar motion of the Sun with respect to the reference frame of the CMBR. This article proposes an alternative interpretation in which the observed dipole is the result of isocurvature perturbations on scales larger than the present Hubble radius. These perturbations are produced in the simplest model of double inflation, depending on three parameters. The observed dipole and quadrupole can be explained in this model, while severely constraining its parameters.Comment: Latex, 9 pages, no figure, to appear in Phys. Rev.

    Antimatter from the cosmological baryogenesis and the anisotropies and polarization of the CMB radiation

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    We discuss the hypotheses that cosmological baryon asymmetry and entropy were produced in the early Universe by phase transition of the scalar fields in the framework of spontaneous baryogenesis scenario. We show that annihilation of the matter-antimatter clouds during the cosmological hydrogen recombination could distort of the CMB anisotropies and polarization by delay of the recombination. After recombination the annihilation of the antibaryonic clouds (ABC) and baryonic matter can produce peak-like reionization at the high redshifts before formation of quasars and early galaxy formation. We discuss the constraints on the parameters of spontaneous baryogenesis scenario by the recent WMAP CMB anisotropy and polarization data and on possible manifestation of the antimatter clouds in the upcoming PLANCK data.Comment: PRD in press with minor change

    Dipole Anisotropy from an Entropy Gradient

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    It is generally accepted that the observed CMBR dipole arises from the motion of the local group relative to the CMBR frame. An alternative interpretation is that the dipole results from an ultra-large scale (λ>100c/H0)\lambda > 100 c/H_0) isocurvature perturbation. Recently it was argued that this alternative possibility is ruled out. We examine the growth of perturbations on scales larger than the Hubble radius and in view of this analysis, we show that the isocurvature interpretation is still a viable explanation. If the dipole is due to peculiar motion then it should appear in observations of other background sources provided that they are distant enough.Comment: 32 uuencoded including two figures, also available at ftp://shemesh.fiz.huji.ac.il or at http://shemesh.fiz.huji.ac.il/lan_pir.p

    First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters

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    We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space Telescope, and a compilation of nearby SN Ia measurements. Combining the SN Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS Luminous Red Galaxy sample and with CMB temperature anisotropy measurements from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a spatially flat cosmological model (FwCDM) with constant dark energy equation of state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia, we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat) +- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M = 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the discrepancy between these results to a difference in the rest-frame UV model combined with a different luminosity correction from color variations; these differences mostly affect the distance estimates for the SNLS and HST supernovae. We present detailed discussions of systematic errors for both light-curve methods and find that they both show data-model discrepancies in rest-frame UU-band. For the SALT-II approach, we also see strong evidence for redshift-dependence of the color-luminosity parameter (beta). Restricting the analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ

    Effect of Intervention With the Self-Determined Learning Model of Instruction on Access and Goal Attainment

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    Promoting self-determination has been identified as best practice in special education and transition services and as a means to promote goal attainment and access to the general education curriculum for students with disabilities. There have been, however, limited evaluations of the effects of interventions to promote self-determination on outcomes related to access to the general education curriculum. This article reports findings from a cluster or group-randomized trial control group study examining the impact of intervention using the Self-Determined Learning Model of Instruction on students’ academic and transition goal attainment and on access to the general education curriculum for students with intellectual disability and learning disabilities. Findings support the efficacy of the model for both goal attainment and access to the general education curriculum, though students varied in the patterns of goal attainment as a function of type of disability.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Prospects for Constraining Cosmology with the Extragalactic Cosmic Microwave Background Temperature

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    Observers have demonstrated that it is now feasible to measure the cosmic microwave background (CMB) temperature at high redshifts. We explore the possible constraints on cosmology which might ultimately be derived from such measurements. Besides providing a consistency check on standard and alternative cosmologies, possibilities include: constraints on the inhomogeneity and anisotropy of the universe at intermediate redshift z<10z ^<_\sim 10; an independent probe of peculiar motions with respect to the Hubble flow; and constraining the epoch of reionization. We argue that the best possibility is as a probe of peculiar motions. We show, however, that the current measurement uncertainty (ΔT=±0.002\Delta T= \pm 0.002 K) in the local present absolute CMB temperature imposes intrinsic limits on the use of such CMB temperature measurements as a cosmological probe. At best, anisotropies at intermediate redshift could only be constrained at a level of >0.1^>_\sim 0.1% and peculiar motions could only be determined to an uncertainty of >311^>_\sim 311 km s1^{-1}. If the high zz CMB temperature can only be measured with a precision comparable to the uncertainty of the local interstellar CMB temperature, then peculiar motions could be determined to an uncertainty of 1101(1+z)1[ΔTCMB(z)/0.01K]kms11101 (1+z)^{-1} [\Delta T_{CMB}(z)/0.01 K] km s^{-1}.Comment: 8 pages 2 Figures, PRD Submitte

    Soil–strain compatibility: the key to effective use of arbuscular mycorrhizal inoculants?

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    Consistency of response to arbuscular mycorrhizal (AM) inoculation is required for efficient use of AM fungi in plant production. Here, we found that the response triggered in plants by an AM strain depends on the properties of the soil where it is introduced. Two data sets from 130 different experiments assessing the outcome of a total of 548 replicated single inoculation trials conducted either in soils with a history of (1) high input agriculture (HIA; 343 replicated trials) or (2) in more pristine soils from coffee plantations (CA; 205 replicated trials) were examined. Plant response to inoculation with different AM strains in CA soils planted with coffee was related to soil properties associated with soil types. The strains Glomus fasciculatum-like and Glomus etunicatum-like were particularly performant in soil relatively rich in nutrients and organic matter. Paraglomus occultum and Glomus mosseae-like performed best in relatively poor soils, and G. mosseae and Glomus manihotis did best in soils of medium fertility. Acaulospora scrobiculata, Diversispora spurca, G. mosseae-like, G. mosseae and P. occultum stimulated coffee growth best in Chromic, Eutric Alluvial Cambisol, G. fasciculatum-like and G. etunicatum-like in Calcaric Cambisol and G. manihotis, in Chromic, Eutric Cambisols. Acaulospora scrobiculata and Diversispora spurca strains performed best in Chromic Alisols and Rodic Ferralsols. There was no significant relationship between plant response to AM fungal strains and soil properties in the HIA soil data set, may be due to variation induced by the use of different host plant species and to modification of soil properties by a history of intensive production. Consideration of the performance of AM fungal strains in target soil environments may well be the key for efficient management of the AM symbiosis in plant production
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