1,769 research outputs found

    Developing transformative schools : a resilience-focused paradigm for education

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    For the better part of the past century, the field of education has witnessed repeated calls and initiatives for change, reform and improvement of our schools. Yet today, the problems of improving academic achievement and social adjustment among youth continue unabated. An explanation for this ā€˜change without changeā€™ phenomenon is offered which differentiates innovative change from transformative change processes. A review of the research evidence regarding resilience and positive youth development, both academically and socially, is utilized to formulate a conceptual framework for guiding educators in creating resilience-focused, transformative schools. Specific attention is addressed to the application of such concepts as mindsets, resilience, socialemotional competencies, and supportive social environments (family and school) in adopting a new, transformative paradigm for developing more effective schools and more capable youth.peer-reviewe

    Testing the Hubble Law with the IRAS 1.2 Jy Redshift Survey

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    We test and reject the claim of Segal et al. (1993) that the correlation of redshifts and flux densities in a complete sample of IRAS galaxies favors a quadratic redshift-distance relation over the linear Hubble law. This is done, in effect, by treating the entire galaxy luminosity function as derived from the 60 micron 1.2 Jy IRAS redshift survey of Fisher et al. (1995) as a distance indicator; equivalently, we compare the flux density distribution of galaxies as a function of redshift with predictions under different redshift-distance cosmologies, under the assumption of a universal luminosity function. This method does not assume a uniform distribution of galaxies in space. We find that this test has rather weak discriminatory power, as argued by Petrosian (1993), and the differences between models are not as stark as one might expect a priori. Even so, we find that the Hubble law is indeed more strongly supported by the analysis than is the quadratic redshift-distance relation. We identify a bias in the the Segal et al. determination of the luminosity function, which could lead one to mistakenly favor the quadratic redshift-distance law. We also present several complementary analyses of the density field of the sample; the galaxy density field is found to be close to homogeneous on large scales if the Hubble law is assumed, while this is not the case with the quadratic redshift-distance relation.Comment: 27 pages Latex (w/figures), ApJ, in press. Uses AAS macros, postscript also available at http://www.astro.princeton.edu/~library/preprints/pop682.ps.g

    Interpreting Martian paleoclimates from valley network morphologies: insights from terrestrial analogues in Egypt

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    Journal ArticleMorphogenetic classification of Martian landforms has provided a context for the inference of surface processes and paleoclimatic conditions on Mars [1][2][3][4][5][6]. The complexity of extensive valley network patterns (Figure 1) suggests that fluvial conditions formerly existed on Mars [7]; however, surface reworking and the lack of absolute age control complicates the precise definition of this time period

    Evaluating the performance of low-energy feed forward osmosis system for desalination using impaired and saline water sources

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    Forward Osmosis (FO) is a natural process of treating water or wastewater due to the difference in osmotic pressures. FO is a membrane separation technology, applicable to food processing, industrial wastewater treatment and seawater or brackish water desalination. The phenomena of FO processes occur whereby water molecules are driven across a semi-permeable membrane by an osmotic pressure gradient that is generated from a higher concentrate draw solution. FO processes can recover potable water resources from wastewater streams through the flow of pure water from a lower concen-trated feed solution towards higher concentrated draw solutions leaving behind pollutants, impurities, and salts in the semi-permeable membrane. This paper assesses the design, build and testing of a laboratory scaled Feed Forward Osmosis (FFO) system for treating river water collected from the River Medway, Kent, England. The FO process was a highly effective form of river water treatment and able to treat the River Water with high rejection rates of solutes (>90%). Experimental results showed that the FFO system can achieve a better performance when the molarity of the draw solution is higher. The average solute rejection rate of the FO membrane for both inorganic and organic compounds was 94.83 %. Moreover, the operation of the forward osmosis membrane illustrated that it has a lower fouling propensity and higher solute rejection ca-pabilities. The pilot scaled FFO system has the ability for greater salt rejection and lower electronic conductivity levels which resulted from the successful desalination of river water. A sodium chloride (NaCl) or saltwater draw solution performed posi-tively in inducing higher osmotic pressures with a substantial effect of lower energy requirements for the system. Lower en-ergy consumptions of the FFO system allow similar water treatment possibilities with energy savings potential. The FFO system showed to be an environmentally viable and economically feasible river water treatment technology

    A Statistical Method for Estimating Luminosity Functions using Truncated Data

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    The observational limitations of astronomical surveys lead to significant statistical inference challenges. One such challenge is the estimation of luminosity functions given redshift zz and absolute magnitude MM measurements from an irregularly truncated sample of objects. This is a bivariate density estimation problem; we develop here a statistically rigorous method which (1) does not assume a strict parametric form for the bivariate density; (2) does not assume independence between redshift and absolute magnitude (and hence allows evolution of the luminosity function with redshift); (3) does not require dividing the data into arbitrary bins; and (4) naturally incorporates a varying selection function. We accomplish this by decomposing the bivariate density into nonparametric and parametric portions. There is a simple way of estimating the integrated mean squared error of the estimator; smoothing parameters are selected to minimize this quantity. Results are presented from the analysis of a sample of quasars.Comment: 30 pages, 9 figures, Accepted for publication in Ap
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