35,768 research outputs found
Integration of Technology in Math and Science Education – A Model for Teaching Elementary and Middle School Pre-Service Teachers
This paper describes the development and implementation of a course, Integration of Technology in Math and Science Education, to introduce elementary and middle school pre-service teachers to real technology skills that they can use in their future classrooms. Activities allowed the students to learn technology skills while using the Internet to enrich their content skills and share information with their fellow students. The course was designed to allow students to master a variety of technology skills, and see how these skills can be used appropriately in their future classrooms, while also increasing their comfort level to use the technology and reduce their resistance and anxiety to use it later in their real-time classrooms. During the class hands-on activities, the students became fluent at using the Internet for enrichment and communication, and at developing strategies for using their new skills to present SOL-relevant lesson plans. Students enter this course with very little in the way of educational technology skills, but leave with a teaching toolbox filled with new skills
Test code for the assessment and improvement of Reynolds stress models
An existing two-dimensional, compressible flow, Navier-Stokes computer code, containing a full Reynolds stress turbulence model, was adapted for use as a test bed for assessing and improving turbulence models based on turbulence simulation experiments. To date, the results of using the code in comparison with simulated channel flow and over an oscillating flat plate have shown that the turbulence model used in the code needs improvement for these flows. It is also shown that direct simulation of turbulent flows over a range of Reynolds numbers are needed to guide subsequent improvement of turbulence models
Spatial Control of Photoemitted Electron Beams using a Micro-Lens-Array Transverse-Shaping Technique
A common issue encountered in photoemission electron sources used in electron
accelerators is the transverse inhomogeneity of the laser distribution
resulting from the laser-amplification process and often use of frequency up
conversion in nonlinear crystals. A inhomogeneous laser distribution on the
photocathode produces charged beams with lower beam quality. In this paper, we
explore the possible use of microlens arrays (fly-eye light condensers) to
dramatically improve the transverse uniformity of the drive laser pulse on UV
photocathodes. We also demonstrate the use of such microlens arrays to generate
transversely-modulated electron beams and present a possible application to
diagnose the properties of a magnetized beam.Comment: arXiv admin note: text overlap with arXiv:1609.0166
Large magnetoresistance using hybrid spin filter devices
A magnetic "spin filter" tunnel barrier, sandwiched between a non-magnetic
metal and a magnetic metal, is used to create a new magnetoresistive tunnel
device, somewhat analogous to an optical polarizer-analyzer configuration. The
resistance of these trilayer structures depends on the relative magnetization
orientation of the spin filter and the ferromagnetic electrode. The spin
filtering in this configuration yields a previously unobserved
magnetoresistance effect, exceeding 100%.Comment: 3.5 pages, 3 figures, submitted to Appl. Phys. Let
Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation
We study the decuplet baryon magnetic moments in a QCD-based quark model
beyond quenched approximation. Our approach for unquenching the theory is based
on the heavy baryon perturbation theory in which the axial couplings for baryon
- meson and the meson-meson-photon couplings from the chiral perturbation
theory are used together with the QM moment couplings. It also involves the
introduction of a form factor characterizing the structure of baryons
considered as composite particles. Using the parameters obtained from fitting
the octet baryon magnetic moments, we predict the decuplet baryon magnetic
moments. The magnetic moment is found to be in good agreement with
experiment: is predicted to be compared to the
experimental result of (2.02 0.05) .Comment: 19 pages, 2 figure
Exactly Solvable Pairing Model Using an Extension of Richardson-Gaudin Approach
We introduce a new class of exactly solvable boson pairing models using the
technique of Richardson and Gaudin. Analytical expressions for all energy
eigenvalues and first few energy eigenstates are given. In addition, another
solution to Gaudin's equation is also mentioned. A relation with the
Calogero-Sutherland model is suggested.Comment: 9 pages of Latex. In the proceedings of Blueprints for the Nucleus:
From First Principles to Collective Motion: A Festschrift in Honor of
Professor Bruce Barrett, Istanbul, Turkey, 17-23 May 200
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