The relative permeability of iron,nickel and permalloy in high frequency electromagnetic fields

The relative magnetic permeability of iron, nickel and permalloy was measured over the range of wave-lengths from 70 to 200 meters by the heterodyne balance method and by the resonance method. Nothing suggestive of the anomalous dispersion of the magnetic permeability reported in this region by Wwedensky and Theodortschik was found when certain precautions were observed in carrying out the measurements. When these precautions were neglected irregular breaks resulted in the curves of permeability as a function of wavelength which varied in position with the conditions of the circuit.The high frequency resistance of iron, nickel and permalloy wires was measured over the range of approximately fifty thousand kilocycles from two to three meter wave-lengths. What appeared to be anomalous variations at certain frequencies were found not to exist when the proper precautions were observed in making the measurements.     

Scholar-Activism: A Twice Told Tale

What does it mean for individuals to intentionally see themselves as scholar-activists? Moreover, what does navigating a scholar-activist life mean for scholars in the early phases of their academic careers? As emerging scholar-activists the authors of this article are continuing to grapple with these questions, and in this article they present their distinct but overlapping stories of working through and overcoming the false separation of scholarship and activism. By sharing their stories the authors want to both provide readers an opportunity to find resonance in their experiences, and present some points to consider as we all define and live scholar-activism. Scholar-activism is historically situated with sights on the future. The authors have chosen to join the struggle of their predecessors in their scholar-activist work, exploring new possibilities sparked by the confluence of different generations.     

Expanding schooling opportunities for 4-year-olds

We use a novel quasi-experimental strategy to estimate the effect of expanding early schooling enrollment possibilities on early achievement. It exploits two features of the school system in The Netherlands. The first is rolling admissions; children are allowed to start school immediately after their 4th birthday instead of at the beginning of the school year. The second is that children having their birthday before, during and after the summer holiday are placed in the same class. These features generate sufficient exogenous variation in children’s enrollment opportunities to identify its effects on test scores. Making available one additional month of time in school increases language scores of disadvantaged pupils by 6 percent of a standard deviation and their math scores by 5 percent of a standard deviation. For non-disadvantaged pupils we find no effect.     

Optimizing Early Mathematics Experiences for Children from Low-Income Families: A Study on Opportunity to Learn Mathematics

Both the National Council of Teachers of Mathematics and the National Association for the Education of Young Children recognize that well-designed opportunity to learn mathematics can help improve mathematics achievement of students from low-income families and from minority backgrounds. Using data from a nationally representative sample, the Early Childhood Longitudinal Study-Kindergarten cohort, this study empirically examined a subset of children from low-income families to determine whether African American and Caucasian students have differential opportunity to learn mathematics and the extent to which opportunities to learn predict gains in mathematics achievement at kindergarten. Results indicated African American kindergartners have differential opportunity to learn mathematics than their Caucasian peers from low-income families. African American students were found to have received, on average, more reported instructional time spent on mathematics, higher use of math manipulatives, worksheets, textbooks and chalkboard work than their Caucasian peers. Moreover, greater opportunity to learn mathematics predicted higher mathematics achievement for both African American and Caucasian students from low-income families, specifically, opportunity to learn skills such as telling time, using measurement tools accurately, estimating quantities, and knowing the value of coins and cash.     

Multi-postpath-based lookahead multiconstraint QoS routing

Multiconstraint QoS (quality of service) routing is an essential mechanism for QoS-guaranteed services. Unfortunately, the multiconstraint QoS routing problem is NP-complete. In this paper, we propose a heuristic multiconstraint QoS routing scheme, MPLMR (multi-postpath-based lookahead multiconstraint routing). MPLMR is a routing scheme using an extended shortest-path algorithm. As in previous schemes such as TAMCRA and H_MCOP, MPLMR stores a limited number of subpaths between the source node and each intermediate node, and extends these subpaths toward the destination node. However, MPLMR uses an improved “lookahead” method to estimate the path length of the full path to which each subpath is extended. MPLMR then selects and stores the subpaths that have higher likelihood than other subpaths to be extended to feasible paths. We show via simulation that MPLMR has a smaller probability of missing a feasible path than competing schemes in the literature.     

Why Do Achievement Measures Underpredict Female Academic Performance?

In the context of college admissions, the current study examined whether differential prediction of first‐year grade point average (FYGPA) by gender could be explained by an omitted variable problem—namely, academic discipline, or the amount of effort a student puts into schoolwork and the degree to which a student sees him/herself as hardworking and conscientious. Based on nearly 10,000 college students, the current study found that differences in intercepts by gender were reduced by 45% with the inclusion of academic discipline in a model that already included high school grade point average (HSGPA) and ACT Composite score. Moreover, academic discipline resulted in an additional 4% of variance accounted for in FYGPA. Gender differences in slopes were not statistically significant (p > .001) regardless if academic discipline was included in the model. The findings highlight the utility of taking a more holistic approach when making college admission decisions. Namely, the inclusion of noncognitive measures has benefits that are twofold: increased predictive validity and reduced differential prediction.     

Using micro-mechanical modelling to predict short-fibre composite properties in computer-aided design of sporting equipment

Computer-aided design (CAD) of sporting equipment requires knowledge of the mechanical properties of proposed materials. The mechanical properties of composite materials are often not as simple to obtain as those of conventional materials, in which case micro-mechanical modelling could be used in conjunction with CAD software. A micro-mechanical model was used to predict the flexural modulus of composite materials, based on the assumption of partial interfacial adhesion between composite components. It was found that the partial adhesion model was both practical and consistently accurate. The partial adhesion model accounted for adhesion between components by considering an ‘effective shear value’ at the interface. The model was compared to experimental data for glass, wood and carbon-fibre reinforced polyethylene. It was shown that the adhesion coefficient ranged between 0.1 for carbon fibre, 0.5 for glass fibre and 0.8 for the wood fibre composites. It was shown that using micro-mechanical modelling to predict composite mechanical properties, as opposed to simulating the comprehensive composites structure, computer processing time and file size can be reduced with little compromise in simulation accuracy.     

Attenuation of blocking with the omission of a delayed US

Two experiments used rats in a CER paradigm to examine the relationship between static-cue conditioning and the attenuation of blocking with a US-omission procedure. Experiment 1 showed that the attenuation of blocking was correlated with static-cue conditioning. Experiment 2 showed that manipulations that normally enhance static-cue conditioning resulted in the attenuation of blocking effect. The implications of these results for current theories of Pavlovian conditioning are discussed.