The Impact of High-Speed Internet Connectivity at Home on Eighth-Grade Student Achievement

In the fall of 2008 Westside Community Schools - District 66, in Omaha, Nebraska implemented a one-to-one notebook computer take home model for all eighth-grade students. The purpose of this study was to determine the effect of a required yearlong one-to-one notebook computer program supported by high-speed Internet connectivity at school on (a) English, (b) math, (c) reading, (d) science, and (e) composite score norm-referenced EXPLORE achievement test scores, District\u27s Criterion-Referenced Descriptive Writing Assessment scores, and classroom performance grade point average (GPA) scores for the core subjects (a) English, (b) science, (c) social studies, and (d) cumulative GPA scores of eighth-grade students who do not have high-speed Internet connectivity at home ( n = 19) compared to eighth-grade students eligible (n = 19) and not eligible (n = 19) for free and reduced price lunch program participation who do have high-speed Internet connectivity at home. The results of this study support the implementation of a one-to-one notebook computer program as a systematic intervention to improve student achievement. Furthermore, all within group pretest-posttest gains and between group posttest-posttest equipoise demonstrated that the achievement gap between students eligible and students not eligible for free or reduced price lunch participation with or without high-speed Internet connectivity at home had been mitigated through participation in the school-wide one-to-one notebook computer program. While the one-to-one notebook eighth-grade computer program in this study may not be singled out solely for between group posttest equipoise causality, its inclusion as a fundamental academic programmatic component of this middle school\u27s curriculum should be considered as a contributing factor

Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073–2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127–135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260–1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (ρ) and atomic number (Z) reconstructions to a significant extent.S.J.L., G.R.M., and A.M.K. acknowledge funding through the DigiCore consortium and the support of a linkage grant (LP150101040) from the Australian Research Council and FEI Company

On the Sequence of Pedal Triangles

Although geometers have studied the properties of triangles for over two thousand years, there still remain problems of interest involving operations performed infinitely often. A given triangle T_0 generates a sequence of triangles T_n where T_(n+1) is the pedal triangle of T_n. This sequence was discussed by Hobson (1897, 1925) but, while his formulae for the transition from T_n to T_(n+1) are correct, those for T_n in terms of T_0 are not. Lacking correct formulae, we experimented numerically, taking the angles of T_0 to be integers in degrees. To our surprise the angles in the pedal sequence became periodic with periods of 12 steps. The explanation of this curious fact led to a general investigation of pedal sequences, revealing that (a) the sequence may stop by degeneration of the triangle to a straight segment, (b) the angles may develop any periodicity, or (c) the sequence may proceed to infinity without any periodicity. We give necessary and sufficient conditions on the angles of T_0 corresponding to these options, and discuss the periodic case in some detail

Anomalously small wave tails in higher dimensions

We consider the late-time tails of spherical waves propagating on even-dimensional Minkowski spacetime under the influence of a long range radial potential. We show that in six and higher even dimensions there exist exceptional potentials for which the tail has an anomalously small amplitude and fast decay. Along the way we clarify and amend some confounding arguments and statements in the literature of the subject.Comment: 13 page

Gravitation Research

Contains research objectives and summary of research.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Aeronautics and Space Administration (Grant NGR 22-009-526)National Science Foundation (Grant GP-24254