Putting Computerized Instruction to the Test: A Randomized Evaluation of a "Scientifically-based" Reading Program

Although schools across the country are investing heavily in computers in the classroom, there is surprisingly little evidence that they actually improve student achievement. In this paper we present results from a randomized study of a well-defined use of computers in schools: a popular instructional computer program, known as Fast ForWord, which is designed to improve language and reading skills. We assess the impact of the program using four different measures of language and reading ability. Our estimates suggest that while use of the computer program may improve some aspects of students' language skills, it does not appear that these gains translate into a broader measure of language acquisition or into actual reading skills.

Coupled Cluster Treatment of the XY model

We study quantum spin systems in the 1D, 2D square and 3D cubic lattices with nearest-neighbour XY exchange. We use the coupled-cluster method (CCM) to calculate the ground-state energy, the T=0 sublattice magnetisation and the excited state energies, all as functions of the anisotropy parameter $\gamma$. We consider $S=1/2$ in detail and give some results for higher $S$. In 1D these results are compared with the exact $S=1/2$ results and in 2D with Monte-Carlo and series expansions. We obtain critical points close to the expected value $\gamma=0$ and our extrapolated LSUBn results for the ground-state energy are well converged for all $\gamma$ except very close to the critical point.Comment: 11 pages, Latex, 4 postscript figure, accepted by J.Phys.: Condens. Matte

Evidence on the Incidence of Wage Posting, Wage Bargaining, and On-the-Job Search

Some workers bargain with prospective employers before accepting a job. Others face a posted wage as a take-it-or-leave-it oppor-tunity. Both modes of wage determination have generated large bodies of research. We surveyed a representative sample of U.S. workers to inquire about the wage determination process at the time they were hired into their current or most recent jobs. A third of the respondents reported bargaining over pay before ac-cepting their current jobs. Almost a third of workers had precise information about pay when they first met with their employers, a sign of wage posting. About 40 percent of workers were on-the-job searchers—they could have remained on their earlier jobs at the time they accepted their current jobs, indicating a more favorable bargaining position than is held by unemployed job-seekers. About half of all workers reported that their employers had learned their pay in their earlier jobs before making the offer that led to the current job

Evidence on the Determinants of the Choice between Wage Posting and Wage Bargaining

Some workers bargain with prospective employers before accepting a job. Others face a posted wage as a take-it-or-leave-it opportunity. Theories of wage formation point to substantial differences in labor-market equilibrium between bargained and posted wages. We surveyed a representative sample of U.S. workers to inquire about the wage determination process at the time they were hired into their current or most recent jobs. A third of the respondents reported bargaining over pay before accepting their current jobs. About a third of workers had precise information about pay when they first met with their employers, a sign of wage posting. About 40 percent of workers could have remained on their earlier jobs at the time they accepted their current jobs, indicating a more favorable bargaining position than is held by unemployed job-seekers. Our analysis of the distribution of wages shows that wage dispersion is higher among workers who bargained for their wages. Wages are higher among bargainers than non-bargainers, after adjusting for the differing compositions of the groups. Our results on wages give substantial support to the job-ladder model--workers who had the option to remain at their earlier jobs when they took their current jobs can earn higher wages than those without that option.

Wage Formation between Newly Hired Workers and Employers: Survey Evidence

Some workers bargain with prospective employers before accepting a job. Others could bargain, but find it undesirable, because their right to bargain has induced a sufficiently favorable offer, which they accept. Yet others perceive that they cannot bargain over pay; they regard the posted wage as a take-it-or-leave-it opportunity. Theories of wage formation point to substantial differences in labor-market equilibrium between bargained and posted wages. The fraction of workers hired away from existing jobs is another key determinant of equilibrium, because a worker with an existing job has a better outside option in bargaining than does an unemployed worker. Our survey measures the incidences of wage posting, bargaining, and on-the-job search. We find that about a third of workers had precise information about pay when they first met with their employers, a sign of wage posting. We find that another third bargained over pay before accepting their current jobs. And about 40 percent of workers could have remained on their earlier jobs at the time they accepted their current jobs.

Active Device Fabrication Using Fiber Encapsulation Additive Manufacturing

Fiber Encapsulation Additive Manufacturing (FEAM) is a novel solid freeform fabrication process in which a fiber and a matrix are co-deposited simultaneously within a single printer along straight and curved 2-D and 3-D paths. Using a FEAM approach in which the fiber is a metal wire and the matrix is a thermoplastic polymer, simple electromechanical devices such as voice coils, inductive sensors, and membrane switches have been successfully produced. This paper will present an overview of the FEAM process, describe several fabricated devices, and discuss recent developments in controllably stopping and starting the wire, and in creating electrical junctions between individual wires, which together enable much more complex devices to be made.Mechanical Engineerin

Flake aligner including baffles supported on continuously moving conveyor

Apparatus for forming a continuous elongated loosely felted mat of thin elongated wood flakes with the flakes being aligned in mutually parallel interleaved relation. The apparatus includes a plurality of belts positioned in adjacent side-by-side relation and for continuous movement so as to define a supporting surface for the mat. A plurality of sets of thin planar baffle plates are provided, each set including a plurality of thin planar baffle plates supported in coplanar alignment and in edge-to-edge adjacent relation. The baffle plates are positioned between a hopper for depositing wood flakes and the supporting surface and function to align the wood flakes in substantially mutually parallel relation in substantially parallel relation to the direction of movement of the supporting surface and to maintain the wood flakes in substantially parallel alignment as the flakes fall from the hopper onto the supporting surface. Each of the sets of baffle plates are positioned between pairs of belts and are supported for movement with the belts, and the baffle plates of one set are parallel to and spaced closely adjacent to baffle plates of an adjacent set.https://digitalcommons.mtu.edu/patents/1119/thumbnail.jp

Butt Joint Reinforcement in Parallel-Laminated Veneer (PLV) Lumber

Parallel-laminated veneer (PLV) is a high-strength structural material consisting of thin parallel-laminated wood veneers. The use of graphite-cloth reinforcement, placed on either side of a butt joint in 1 1/2- by 3 1/2- by 32-inch Douglas-fir PLV tensile members, was assessed. The finite-element method of analysis was used to predict the behavior in different unreinforced and reinforced butt-jointed PLV tensile members. Relationships between the reinforcing parameters—length, modulus of elasticity, and thickness—and the stresses in the wood and reinforcement components were developed by regression analysis techniques. The reinforcing mechanism reduced the peak stresses at the butt joint and hence increased the ultimate strength of the member. Design of PLV material whose strength is limited by shear stresses that develop at the butt joint is facilitated by use of the proposed relationships.Experimental testing confirmed the predictions of the finite-element analysis. Failure initiated at the unreinforced joint in the specimens. Average tensile strength increased and variability decreased in reinforced specimens. Application of a small amount of reinforcement at the butt joint has been shown to enhance PLV performance