57 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.

    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

    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 s−1^{-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]kms−11101 (1+z)^{-1} [\Delta T_{CMB}(z)/0.01 K] km s^{-1}.Comment: 8 pages 2 Figures, PRD Submitte

    Iron oxides and organic matter on soil phosphorus availability

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    Phosphorus: its efficient use in agriculture

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    Changes in understanding the behavior of soil and fertilizer phosphorus (P) during the last 150 years are presented and recent concepts have been linked with agronomic data to produce a model that considers four pools of inorganic soil P related to their plant availability and extractability by chemical extractants. The stronger the bonding of phosphate ions to soil components, the lower the plant availability. P-use efficiency in agriculture is related to soils reaching and being maintained at a critical level of readily plant-available P, and factors affecting the critical level are discussed. Efficiency can be assessed by the direct, difference, and balance methods. The latter, calculated as the P output/input ratio, shows that P-use efficiency can exceed 80–90%. Combined data from controlled experiments in England and derived “statewide” aggregate information in the United States relating output/input ratios to changes in plant-available P could best be described by a single, simple function, making a powerful and convincing statement suggesting that there is an underlying “simple rule” for the behavior of plant-available inorganic soil P that is related to the four-pool concept discussed.&nbsp
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