57 research outputs found
Cosmic Microwave Background Dipole induced by double inflation
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
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 (
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
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 studentsâ 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
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 ; 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 (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 and peculiar
motions could only be determined to an uncertainty of km
s. If the high 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 .Comment: 8 pages 2 Figures, PRD Submitte
Phosphorus: its efficient use in agriculture
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 80â90%. Combined data from controlled experiments in England and derived âstatewideâ 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 âsimple ruleâ for the behavior of plant-available inorganic soil P that is related to the four-pool concept discussed. 
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