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Channel routing is important in flood forecasting and watershed modeling. The general constant-parameter Muskingum-Cunge (CPMC) method is second-order accurate and easy to implement. With specific discretizations such that the temporal and spatial intervals maintain a unique relationship, the CPMC method can be third-order accurate. In this paper, we derive the average lateral inflow term in the second- and third-order accuracy CPMC method, and demonstrate that For spatially and temporally variable lateral inflow, the effect of lateral inflow on simulated discharge varies with spatial and temporal discretizations, the value and spatial and temporal variations of lateral inflow, wave celerity, and diffusion coefficient. Comparison of the CPMC solution with the analytical solution shows that both the second- and third-order accuracy schemes are more accurate than the simplified method by which spatial derivatives of lateral inflow are ignored. For small time steps, the third-order accuracy CPMC method results in higher accuracy than the second-order scheme even when the third-order accuracy criterion is not fully met. For large time steps, the temporal and spatial discretization of the third- and second-order scheme becomes the same, but the third-order scheme yields higher accuracy than the second-order scheme because of the third-order accurate estimation of the lateral inflow term.

Math and science textbook chapters invariably supply students with sets of problems to solve, but this widely used approach is not optimal for learning; instead, more effective learning can be achieved when many problems to solve are replaced with correct and incorrect worked examples for students to study and explain. In the present study, the worked example approach is implemented and rigorously tested in the natural context of a functioning course. In Experiment 1, a randomized controlled study in ethnically diverse Algebra classrooms demonstrates that embedded worked examples can improve student achievement. In Experiment 2, a larger randomized controlled study demonstrated that improvement in posttest scores as a result of the assignments varies based on students' prior knowledge; students with low prior knowledge tend to improve more than higher knowledge peers. [This paper was published in " Journal of Research on Educational Effectiveness" (EJ1078793).]

Atomic Layer Deposition (ALD) is a promising technique for producing Josephson junctions (JJs) with lower defect densities for qubit applications. A key problem with using ALD for JJs is the interfacial layer (IL) that develops underneath the tunnel barrier. An IL up to 2 nm forms between ALD Al2O3 and Al. However, the IL thickness is unknown for ALD films less 1 nm. In this work, Nb-Al-ALD-Al2O3-Nb trilayers with tunnel barriers from 0.6 - 1.6 nm were grown in situ. Nb-Al-AlOx-Nb JJs with thermally oxidized tunnel barrier were produced for reference. RN was obtained using a four-point method at 300 K. JC, and its dependence on barrier thickness, was calculated from the Ambegaokar-Baratoff formula. The Al surface was modeled using ab initio molecular dynamics to study the nucleation of Al2O3 on Al. Current voltage characteristics were taken at 4 K to corroborate the room temperature measurements. Together, these results suggest that ALD may be used to grow an ultrathin, uniform tunnel barrier with controllable tunnel resistance and JC, but a thin IL develops during the nucleation stage of ALD growth that may disqualify Al as a suitable wetting layer for ALD JJ based qubits., Comment: 5 pages, 4 figures, Applied Superconductivity Conference

Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barrier using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb/Al/Al2O3/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ~ 1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers., Comment: 25 pages, 13 figures, 1 table

Biaxially textured MgO templates have been successfully fabricated on several amorphous polymer films including Kapton tapes, polyimide, Poly(methyl methacrylate) (PMMA), and photoresist films using ion-beam-assisted-deposition (IBAD). With a Y2O3 buffer layer on polymer surfaces, roughening of the polymer surfaces due to preferential ion beam sputtering can be effectively reduced to meet the surface compatibility requirement for IBAD-MgO texturing. In-plane full-width-at-half-maximum (FWHM) of ~10.7 degrees and out-of-plane FWHM ~ 3.5 degrees have been obtained on homoepitaxial MgO films grown on top of the IBAD-MgO template. This method provides a practical route for fabricating epitaxial devices on polymers needed for flexible optoelectronics., Comment: 8 pages, 3 figures

Atomic layer deposition (ALD) provides a promising approach for deposition of ultrathin low-defect-density tunnel barriers, and it has been implemented in a high-vacuum magnetron sputtering system for in situ deposition of ALD-Al2O3 tunnel barriers in superconductor-insulator-superconductor (SIS) Josephson junctions. A smooth ALD-Al2O3 barrier layer was grown on a Al-wetted Nb bottom electrode and was followed with a top Nb electrode growth using sputtering. Preliminary low temperature measurements of current-voltage characteristics (IVC) of the Josephson junctions made from these trilayers confirmed the integrity of the ALD-Al2O3 barrier layer. However, the IcRN product of the junctions is much smaller than the value expected from the Ambegaokar-Baratoff formula suggesting a significant pair-breaking mechanism at the interfaces., Comment: 4 pages, 4 figures

Ultrathin dielectric tunneling barriers are critical to Josephson junction (JJ) based superconducting quantum bits (qubits). However, the prevailing technique of thermally oxidizing aluminum via oxygen diffusion produces problematic defects, such as oxygen vacancies, which are believed to be a primary source of the two-level fluctuators and contribute to the decoherence of the qubits. Development of alternative approaches for improved tunneling barriers becomes urgent and imperative. Atomic Layer Deposition (ALD) of aluminum oxide (Al2O3) is a promising alternative to resolve the issue of oxygen vacancies in the Al2O3 tunneling barrier, and its self-limiting growth mechanism provides atomic-scale precision in tunneling barrier thickness control. A critical issue in ALD of Al2O3 on metals is the lack of hydroxyl groups on metal surface, which prevents nucleation of the trimethylaluminum (TMA). In this work, we explore modifications of the aluminum surface with water pulse exposures followed by TMA pulse exposures to assess the feasibility of ALD as a viable technique for JJ qubits. ALD Al2O3 films from 40 angstroms to 100 angstoms were grown on 1.4 angstroms to 500 angstroms of Al and were characterized with ellipsometry and atomic force microscopy. A growth rate of 1.2 angstroms/cycle was measured, and an interfacial layer (IL) was observed. Since the IL thickness depends on the availability of Al and saturated at 2 nm, choosing ultrathin Al wetting layers may lead to ultrathin ALD Al2O3 tunneling barriers., Comment: 4 pages, 4 figures

Examines the relationship between undergraduates' perception of their classroom environment, their adoption of achievement goals for the course, and their graded performance and intrinsic motivation. Results reveal that each of the three achievement goals evidenced a distinct antecedent profile. Proposes that achievement goals serve the role of proximal predictor of achievement outcomes. (Contains 54 references and 3 tables.) (GCP)

Recent and future activities of the Center for Education Statistics (CES) of the Department of Education are discussed. The purpose of the CES is to provide information about the status and progress of education to the American public. Center activities and features discussed include specific data-gathering efforts, growth in technical capabilities, dramatic changes in funding, responsibilities and authority, and outside sources of advisement, and information dissemination. The merger of the National Assessment for Educational Progress and the Schools Staffing Survey is discussed, and problems are identified in the context of a broader discussion of the link between statistics and research. (TJH)

Identifies three methodological shortcomings of the classic Princeton trilogy studies, and addresses these shortcomings in a study of University of Wisconsin-Madison students (n=147). Results suggest that there exists a consistent and negative contemporary stereotype of blacks. (JPS)

Bell Nozzle Kernel Analysis Program computes and analyzes the supersonic flowfield in the kernel, or initial expansion region, of a bell or conical nozzle. It analyzes both plane and axisymmetric geometrices for specified gas properties, nozzle throat geometry and input line.