Cost-efficient manufacturing of composite structures

The Advanced Composites Technology (ACT) program is seeking research breakthroughs that will allow structures made of graphite epoxy materials to replace metals in the wings and fuselages of future aircrafts. NASA's goals are to reduce acquisition cost by 20 to 25 percent, structural weight for a resized aircraft by 40 to 50 percent, and the number of parts by half compared to current production aluminum aircraft. The innovative structural concepts, materials, and fabrication techniques emerging from the ACT program are described, and the relationship between aerospace developments and industrial, commercial, and sporting goods applications are discussed

Effects of the Learning Opportunities Task Force (LOTF) Programs on Postsecondary Students with Learning Disabilities

This study examined the effects of participation in the Learning Opportunities Task Force (LOTF) programs on postsecondary students with learning disabili-ties (LDs). Data regarding 969 students from 6 colleges and 4 universities in Ontario were evaluated to investigate rates of academic success and increased self-awareness. Participants had a significantly lower rate of failure or drop out compared with the national average. Comparison of pre- and post-participation data from 450 of these students demonstrated improved understanding of their own LD, ability to explain their disability to others, and ability to self-advocate following participation in the LOTF programs. Overall, the majority of partici-pants reported that participation in the LOTF program contributed significantly to their academic success and would participate again in such a program. Inten-sive learning supports during the first year of postsecondary studies like those provided by LOTF may increase retention rates and improve key skills for those with LD

X-ray imaging of the Seyfert 2 galaxy Circinus with Chandra

We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of the galaxy, embedded in diffuse X-ray emission. The latter shows a prominent (~18arcsec) soft ``plume'' in the N-W direction, coincident with the [OIII] ionization cone. The radial profiles of the brightest X-ray source at various energies are consistent with an unresolved (FWHM ~0.8arcsec) component, which we identify as the active nucleus, plus two extended components with FWHMs ~ 2.3arcsec and 18arcsec, respectively. In a radius of 3arcsec, the nucleus contributes roughly the same flux as the extended components at the softest energies (< 2 keV). However, at harder energies (> 2 keV), the contribution of the nucleus is dominant. The zeroth-order ACIS spectrum of the nucleus exhibits emission lines at both soft and hard X-rays, including a prominent Fe Kalpha line at 6.4 keV, showing that most of the X-ray lines previously detected with ASCA originate in a compact region (<15 pc). Based on its X-ray spectrum, we argue that the 2.3arcsec extended component is scattered nuclear radiation from nearby ionized gas. The large-scale extended component includes the emission from the N-W plume and possibly from the outer starburst ring.Comment: Figure 1 in color. ApJ Letters, in pres

High Fidelity Single Qubit Operations using Pulsed EPR

Systematic errors in spin rotation operations using simple RF pulses place severe limitations on the usefulness of the pulsed magnetic resonance methods in quantum computing applications. In particular, the fidelity of quantum logic operations performed on electron spin qubits falls well below the threshold for the application of quantum algorithms. Using three independent techniques, we demonstrate the use of composite pulses to improve this fidelity by several orders of magnitude. The observed high-fidelity operations are limited by pulse phase errors, but nevertheless fall within the limits required for the application of quantum error correction.Comment: 4 pages, 3 figures To appear in Phys. Rev. Let

Measuring errors in single qubit rotations by pulsed electron paramagnetic resonance

The ability to measure and reduce systematic errors in single-qubit logic gates is crucial when evaluating quantum computing implementations. We describe pulsed electron paramagnetic resonance (EPR) sequences that can be used to measure precisely even small systematic errors in rotations of electron-spin-based qubits. Using these sequences we obtain values for errors in rotation angle and axis for single-qubit rotations using a commercial EPR spectrometer. We conclude that errors in qubit operations by pulsed EPR are not limiting factors in the implementation of electron-spin based quantum computers

Academic Resilience: A Retrospective Study of Adults With Learning Difficulties

This article reports qualitative analyses of two sets of retrospective interviews with adults with learning difficulties. The purpose of the study was to examine the high school experiences of these adults from a holistic perspective to understand possible factors that contributed to one group staying in school and the other group leaving school early. One set of interviews was conducted with adults who had returned to complete high school at an adult learning center (the late successful group). The second set of interviews was conducted with the early successful group, adults who had completed high school during adolescence. Interview questions focused on interests, friends, and general aspects of the high school experience. Analyses yielded three themes: intrapersonal support, interpersonal support, and institutional support. These data suggest that schools might act in a number of ways to counter the high rate of early leaving by adolescents with learning disabilities, including building strong teacher-student relationships, using students' interests to develop curricula and structured activities, and fostering a sense of purpose.Cet article expose deux analyses qualitatives de deux séries d'entrevues rétrospectives auprès d'adultes présentant des difficultés d'apprentissage. Le but de l'étude consistait à examiner, dans une perspective holistique, les expériences qu'avaient vécues ces adultes quand ils étaient au secondaire, pour ensuite déterminer si des facteurs avaient influencé le fait que certaines personnes étaient restées à l'école alors que d'autres avaient décroché. Une série d'entrevues a été effectuée auprès d'adultes qui avaient repris leurs études secondaires dans un institut d'apprentissage pour adultes (le groupe de diplômés tardifs). La deuxième série d'entrevues a eu lieu auprès d'adultes ayant terminé l'école secondaire alors qu'ils étaient adolescents dégroupe de diplômés précoces). Les questions d'entrevues portaient sur les intérêts, les amis et les aspects généraux de leur expérience à l'école secondaire. Trois thèmes sont ressortis des analyses: l'appui intrapersonnel, l'appui interpersonnel et l'appui institutionnel. Ces données donnent à penser que les écoles pourraient intervenir de diverses façons pour contrer le taux élevé de décrochage chez les adolescents ayant des difficultés d'apprentissage. Parmi ces stratégies notons la création de rapports solides entre les enseignants et les élèves, le développement de programmes d'études et d'activités structurées basés sur les intérêts des élèves et le fait de favoriser des buts bien précis

The Role of Interest in Fostering Sixth Grade Students' Identities As Competent Learners

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72489/1/0362-6784.00153.pd

Halo Star Streams in the Solar Neighborhood

We have assembled a sample of halo stars in the solar neighborhood to look for halo substructure in velocity and angular momentum space. Our sample includes red giants, RR Lyrae, and red horizontal branch stars within 2.5 kpc of the Sun with [Fe/H] less than -1.0. It was chosen to include stars with accurate distances, space velocities, and metallicities as well as well-quantified errors. We confirm the existence of the streams found by Helmi and coworkers, which we refer to as the H99 streams. These streams have a double-peaked velocity distribution in the z direction. We use the results of modeling of the H99 streams by Helmi and collaborators to test how one might use v_z velocity information and radial velocity information to detect kinematic substructure in the halo. We find that detecting the H99 streams with radial velocities alone would require a large sample. We use the velocity distribution of the H99 streams to estimate their age. From our model of the progenitor of the H99 streams, we determine that it was accreted between 6 and 9 Gyr ago. The H99 streams have [alpha/Fe] abundances similar to other halo stars in the solar neighborhood, suggesting that the gas that formed these stars were enriched mostly by Type II SNe. We have also discovered in angular momentum space two other possible substructures, which we refer to as the retrograde and prograde outliers. The retrograde outliers are likely to be halo substructure, but the prograde outliers are most likely part of the smooth halo. The retrograde outliers have significant structure in the v_phi direction and show a range of [alpha/Fe]. The methods presented in this paper can be used to exploit the kinematic information present in future large databases like RAVE, SDSSII/SEGUE, and Gaia.Comment: 46 pages, 13 figures, and 9 tables. Minor changes to text to match proofed version of the paper. Low resolution figures. High resolution version at http://www.astro.wisc.edu/~kepley/solar_streams.p