EMU Ag-Zn battery wet-life extension test

The Extravehicular Mobility Unit (EMU) silver/zinc (Ag/Zn) battery is an 11 cell battery of approximately 30 AH. The Ag/Zn battery is comprised of two 4-cell monoblocks and one 3-cell monoblock. A discussion of a wet-life extension test performed on the battery is given in viewgraph form

A Computer Simulation Model of Waterhyacinth and Weevil Interactions

A personal computer simulation model termed INSECT has been developed to evaluate biological control of waterhyacinth (Eichhornia crassipes (Mart.) Solms.) by two species of weevil (Neochetina eichhorniae Warner, and N. bruchi Hustache). The model results were compared with the data from three different locations. For each data set, the simulated plant biomass, adult and larva populations were plotted aqainst the 95% confidence intervals of the actual field observations. In many cases, the simulation results were within the 95% confidence intervals, and especially during the growing season, they indicated trends similar to those seen in the field data. However, there were discrepancies in both the magnitude and the trend for early and the late periods of the year. These initial results suggest that development of a model to simulate the impact of a biocontrol agent on waterhyacinth populations is a feasible approach to better understand the interactions within this control system

Electronic Structure of Lithium Tetraborate

Due to interest as neutron detection material, an investigation of Li2B4O7(110) and Li2B4O7(100) was undertaken, utilizing photoemission and inverse photoemission spectroscopic techniques. The measured band gap depended on crystallographic direction with the band gaps ranging from 8.9±0.5 eV to 10.1±0.5 eV. The measurement yielded a density of states that qualitatively agreed with the theoretical results from model bulk band structure calculations for Li2B4O7; albeit with a larger band gap than predicted, but consistent with the known deficiencies of LDA and DFT calculations. The occupied states of both surfaces were extremely flat; to the degree that resolving periodic dispersion of the occupied states was inconclusive, within the resolution of the system. However, both surfaces demonstrated clear periodic dispersion within the empty states very close to theoretical Brillouin zone values. These attributes also translated to a lighter charge carrier effective mass in the unoccupied states. Li2B4O7(110) yielded the more consistent values in orthogonal directions for energy states. The presence of a bulk band gap surface state and image potential state in Li2B4O7(110) was indicative of a defect-free surface. The absence of both in the more polar, more dielectric Li2B4O7(100) was attributed to the presence of defects determined to be O vacancies. The results from Li2B4O7(110) were indicative of a more stable surface than Li2B4O7(100). In addition, Li 1s bulk and surface core level components were determined at the binding energies of -56.5+0.4 and -53.7+0.5 eV. Resonance features were observed along the [001] direction and were attributed to a Coster-Kronig process. The pyroelectric and piezoelectric character of Li2B4O7 was explored more deeply and a non-zero, off-axis pyroelectric coefficient for the Li2B4O7(110) direction was discovered

The electron-boson spectral density function of underdoped Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} and YBa2_2Cu3_3O

We investigate the electron-boson spectral density function, $I^2\chi(\omega,T)$, of CuO$_2$ plane in underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi-2212) and underdoped YBa$_2$Cu$_3$O$_{6.50}$ (Y-123) using the Eliashberg formalism. We apply a new (in-plane) pseudogap model to extract the electron-boson spectral function. For extracting the spectral function we assume that the spectral density function consists of two components: a sharp mode and the broad Millis-Monien-Pines (MMP) mode. We observe that both the resulting spectral density function and the intensity of the pseudogap show strong temperature dependences: the sharp mode takes most spectral weight of the function and the peak position of the sharp mode shifts to lower frequency and the depth of pseudogap, $1-\tilde{N}(0,T)$, is getting deeper as temperature decreases. We observe also that the total spectral weight of the electron-boson density and the mass enhancement coefficient increase as temperature decreases. We estimate fictitious (maximum) superconducting transition temperatures, $T_c(T)$, from the extracted spectral functions at various temperatures using a generalized McMillan formula. The estimated (maximum) $T_c$ also shows a strong temperature dependence; it is higher than the actual $T_c$ at all measured temperatures and decreases with temperature lowering. Since as lowering temperature the pseudogap is getting stronger and the maximum $T_c$ is getting lower we propose that the pseudogap may suppress the superconductivity in cuprates.Comment: 8 pages, 6 figure

Electrical Conductivity Induced in Insulators by Pulsed Radiation

The minimum prompt photoconductivity induced by pulses of x rays, gamma rays, and energetic electrons in various amorphous and disordered insulating organic and inorganic materials is predicted on the basis of data for the scattering of hot electrons in solids and the band gap for insulators. For total doses of 3 x 10^4 to 30 x 10^4 rad or greater, the minimum prompt photoconductivity is predicted to be linear with dose rate, γ, and is given by σ(Ω^(-1)cm^(-1))=5 x 10^(-19) ρ_0γ/E_g^2, where ρ_0 is the density (g/cm^3) and Eg is the optical band gap (eV). This formula agrees well with data for a variety of plastics, mica, and borosilicate glass under widely different irradiation conditions. The formula considerably underestimates absolute values of prompt conductivities observed for Al_2O_3, MgO, and certain plastics, because the model does not hold for ordered materials

Nothing about Us Without Us: Practical Strategies for Accessible Pedagogy

This chapter explores practical strategies based on the lived experiences of the authors, who are disabled graduate instructors. Theoretical approaches to accessible pedagogy should be rooted in praxis that accounts for the material realities of the disabled people it professes to be for. Most classroom interventions at present are accommodations, which are based on the medical model of disability; this chapter describes an approach to accessible pedagogy rooted in the social model of disability, and an ethics of disability justice. Instructors can explore ways of implementing accessible praxis by rethinking the ableist assumptions inherent in such areas as time, space, grading, participation, and technology

A study of the structure of jet turbulence producing jet noise

Characteristics of turbulent structure of mixing region near outlet of circular subsonic jet and production of jet nois

Assessing proxies of knowledge and difficultywith rubric-based instruments

The fields of psychometrics, economic education, and education have developed statistically-valid methods of assessing knowledge and learning. These methods include item response theory, value-added learning models, and disaggregated learning. These methods, however, focus on multiple-choice or single response assessments. Faculty and administrators routinely assess knowledge through papers, thesis presentations, or other demonstrations of knowledge assessed with rubric rows. This paper presents a statistical approach to estimating a proxy for student ability and rubric row difficulty. Moreover, we have developed software so that practitioners can more easily apply this method to their instruments. This approach can be used in researching education treatment effects, practitioners measuring learning outcomes in their own classrooms, or estimating knowledge for administrative assessment. As an example, we have applied these new methods to projects in a large Labor Economics course at a public university

Create random assignments: A cloud-based tool to help implement alternative teaching materials

Research has shown that learning is enhanced by variety (Bransford, Brown, and Cocking 2000; Halpern and Hakel 2003) such as popular press books, podcasts and videos. However, these mediums do not contain question banks and further, while learning management systems (LMS) can be used to generate random quizzes, they are not designed for long-form open-ended responses that might be answered over the course of a few days to weeks; open-ended questions are often ideal in upper-level undergraduate and MBA courses where there are less definitive correct answers. We solve these problems by developing software to generate assignments with randomized open-ended questions