2,694 research outputs found

    Infinite slabs and other weird plane symmetric space-times with constant positive density

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    We present the exact solution of Einstein's equation corresponding to a static and plane symmetric distribution of matter with constant positive density located below z=0z=0. This solution depends essentially on two constants: the density ρ\rho and a parameter κ\kappa. We show that this space-time finishes down below at an inner singularity at finite depth. We match this solution to the vacuum one and compute the external gravitational field in terms of slab's parameters. Depending on the value of κ\kappa, these slabs can be attractive, repulsive or neutral. In the first case, the space-time also finishes up above at another singularity. In the other cases, they turn out to be semi-infinite and asymptotically flat when z→∞z\to\infty. We also find solutions consisting of joining an attractive slab and a repulsive one, and two neutral ones. We also discuss how to assemble a "gravitational capacitor" by inserting a slice of vacuum between two such slabs.Comment: 8 page

    A Critical Analysis Of Time Allocation In Psychoeducational Evaluations

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    This study provides results form a national survey examining school psychologists’ allocation of time in psycholeducational evaluations. A total of 177 participants with an average of 13.45 years professional experience in school psychology, representing 39 states, participated in the survey. The results indicate that school psychologists spend the majority of their time engaging in test administration and report-writing components of the evaluation process. The data also revealed that the evaluation of students with possible emotional disabilities is most time intensive when compared to evaluations of students with possible learning or intellectual disabilities.  Implications of the results relating to policy and procedures to improve the learning outcomes of students in public school settings are provided

    Identifying the Effects of Specific CHC Factors on College Students’ Reading Comprehension

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    Reading comprehension is an important skill for college academic success. Much of the research pertaining to reading in general, and reading comprehension specifically, focuses on the success of primary and secondary school-age students. The present study goes beyond previous research by extending such investigation to the reading comprehension of college-age student participants. Using the Cattell-Horn-Carroll (CHC) theoretical model, this study investigates the effects of seven broad factors on the reading comprehension of college-age students. Of the seven broad factors identified within the CHC theoretical model, only crystallized intelligence and visual-spatial thinking demonstrate statistically significant direct effects on reading comprehension. Although crystallized intelligence consistently has been identified as playing an integral role in the reading comprehension of primary and secondary school-age students, this study represents the first time visual-spatial thinking has been found to have a statistically significant direct effect on reading comprehension, in any population. This study provides hypotheses to explain the effects of visual-spatial thinking on college-age students’ reading comprehension and offers instructional strategies to assist faculty in improving student learning in higher education settings

    Study of quasi-optical circuit techniques in varactor multipliers

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    Quasi-optical circuit techniques in varactor multiplier

    The Effects Of Training In Timing And Rhythm On Reading Achievement

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    This study investigated the relationship between improvement in students’ timing/rhythmicity and reading achievement. Two hundred eighty high school-age participants completed pre- and post-test measures from the Woodcock-Johnson Tests of Achievement-III (Woodcock, McGrew, & Mather, 2001). Students in the experimental group participated in a timing/rhythm intervention designed to reduce their latency response to a reoccurring metronome beat. Students in the control group participated in traditional classroom activities. The results from the study indicate that after treatment, the experimental group’s post-test Broad Reading and Reading Fluency scores were statistically significantly higher than the non-treatment control group’s post-test scores

    Improving Mathematics: An Examination of the Effects of Specific Cognitive Abilities on College-age Students’ Mathematics Achievement

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    This study investigated the effects of general intelligence and seven specific cognitive abilities on college-age students’ mathematics achievement. The present investigation went beyond previous research by employing structural equation modeling. It also represents the first study to examine the direct and indirect effects of general and specific cognitive abilities, simultaneously, on the mathematics achievement of college-age students. A model developed using the Cattell-Horn-Carroll theory of intelligence was the theoretical model used in all analyses. Data from 1,054 college-age students who participated in the standardization of the Woodcock–Johnson III (Woodcock, McGrew, & Mather, 2001) were divided into a calibration sample set and validation sample set. The calibration data set was used for model testing and modification and the independent validation sample data set was used for model validation. The specific areas of intelligence demonstrating direct effects on the mathematics achievement dependent variable were Crystallized Intelligence and Fluid Reasoning. The effects of general intelligence were found to be indirect in the college-age sample. Implications for instruction and intervention to improve college student’s mathematics achievement are provided

    The Efroimsky formalism adapted to high-frequency perturbations

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    The Efroimsky perturbation scheme for consistent treatment of gravitational waves and their influence on the background is summarized and compared with classical Isaacson's high-frequency approach. We demonstrate that the Efroimsky method in its present form is not compatible with the Isaacson limit of high-frequency gravitational waves, and we propose its natural generalization to resolve this drawback.Comment: 7 pages, to appear in Class. Quantum Gra
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