4,433 research outputs found
Recent results from zero g cargo handling studies
Cargo handling, transfer, and stowage under weightlessness conditions of space shuttl
Macroinvertebrates, Heavy Metals and PAHs in Urban Watercourses
Good quality stream water and sediments are crucial for the support of healthy stream flora and fauna but urban runoff degrades watercourses leaving a legacy of pollution in the stream sediments. The sediment pollution load influences the development of macroinvertebrates which, as the lowest member of the food chain, influences the whole ecological structure. This review focuses on defining the sources and impacts of zinc, nickel, copper and oil derivative polycyclic aromatic hydrocarbon (PAH) contaminants in urban runoff. The impact of pollutants as measured by laboratory, field and modelling procedures are considered. Land use, position and connectivity of the runoff and sediment are seen to have an effect on the ecological integrity of the watercourse but case examples are sparse. The literature indicates that while reduced species diversity has been identified at a number of sites the dynamics are not well understood nor well modelled. These results are compared with field evidence from a study of 62 headwater streams with urban industrial and motorway land uses. From the review and field results it is evident that there is still an important need for process-based field measurements of urban water quality parameters. Forecasting the ecological status of watercourses would seem to benefit from data on sediment chemistry that considers the interaction effects of metals and PAHs
Analysis of combinations of altitude and descent rate for safe abort during terminal phase of lunar landing
Boundary curve for combinations of altitude and descent rate for safe abort during terminal phase of lunar landin
Upgrading of AMTRAN on the datacraft DC 6024
A number of new software extensions and modifications to the AMTRAN system were completed. These modifications include input/output alterations, one-dimensional and two-dimensional array improvements, and disk storage of data enhancements. In order to promote a better understanding of the AMTRAN system software structure, a general description of the AMTRAN modules and their interrelationships was provided. A few sample statements have also been traced through the compilation and execution stages in order to illustrate the flow of system logic. In addition, the previous documentation was updated to reflect these modifications
X-Ray Emitting Ejecta of Supernova Remnant N132D
The brightest supernova remnant in the Magellanic Clouds, N132D, belongs to
the rare class of oxygen-rich remnants, about a dozen objects that show optical
emission from pure heavy-element ejecta. They originate in explosions of
massive stars that produce large amounts of O, although only a tiny fraction of
that O is found to emit at optical wavelengths. We report the detection of
substantial amounts of O at X-ray wavelengths in a recent 100 ks Chandra ACIS
observation of N132D. A comparison between subarcsecond-resolution Chandra and
Hubble images reveals a good match between clumpy X-ray and optically emitting
ejecta on large (but not small) scales. Ejecta spectra are dominated by strong
lines of He- and H-like O; they exhibit substantial spatial variations
partially caused by patchy absorption within the LMC. Because optical ejecta
are concentrated in a 5 pc radius elliptical expanding shell, the detected
ejecta X-ray emission also originates in this shell.Comment: 5 pages, 6 figures, ApJ Letters, in pres
Implementing a Successful Collaborative Learning Environment
This action research report summarizes a study of 65 diverse student learners in a 10th grade AP US History class. This research investigates the implementation of a collaborative learning environment to elicit positive effects on student attitudes toward learning and their achievement. To gain pre-intervention data, students were surveyed on their attitudes and took multiple-choice assessments. During the intervention period, students completed surveys regarding the effectiveness of the collaborative learning implementation and completed multiple-choice assessments. After the interventions, students were surveyed again on their attitudes toward learning. The results demonstrated insignificant effects on student attitudes but improvements in student achievement. Data supports concluding that collaborative learning may impact student retention of content and learning objectives. Future research may indicate whether the execution of such interventions over a longer period of time would have more considerable outcomes in the areas of retention or student attitudes about learning
Administrators Using Technology to Increase Family Engagement
The purpose of this study was to investigate and evaluate what happens when Title 1 administrators implement emerging technologies to facilitate school-home communications. This study explored the affordances and constraints to using technology tools to promote family engagement, determined which characteristics of the tools allowed parents to feel the most informed, measured how many parents attended school events, and evaluated parents’ perceptions of invitations to involvement when administration used technology tools to communicate. Epstein’s Parental Involvement Framework (2002), Epstein’s Overlapping Spheres of Influence (1995), and the Hoover-Dempsey and Sandler Model (1997) served as the theoretical framework. This mixed methods study was conducted at a small, urban, Title 1 elementary school in a Southeastern state. A sequential explanatory design was used. During the quantitative phase a Parent Communication Survey was collected from 51 participants. During the qualitative phase artifacts were collected and focus group interviews were conducted with nine participants. This study revealed affordances and constraints for each of the emerging technology tools. Communication tools that were available on parents’ cell phones were the most effective at informing families about school programs and student success. Systematically scheduled communications aided parents in better planning which enabled them to become more engaged. Administration was able to have an impact on parents’ perceptions of invitations to involvement through the use of technology tools. This study includes recommendations for future research and implications for practice
NASA Aircraft Controls Research, 1983
The workshop consisted of 24 technical presentations on various aspects of aircraft controls, ranging from the theoretical development of control laws to the evaluation of new controls technology in flight test vehicles. A special report on the status of foreign aircraft technology and a panel session with seven representatives from organizations which use aircraft controls technology were also included. The controls research needs and opportunities for the future as well as the role envisioned for NASA in that research were addressed. Input from the panel and response to the workshop presentations will be used by NASA in developing future programs
Quenching of Impurity Spins at Cu/CuO Interfaces: An Antiferromagnetic Proximity Effect
It is observed that the magnetoconductance of bilayer films of copper (Cu)
and copper monoxide (CuO) has distinct features compared of that of Cu films on
conventional band insulator substrates. We analyze the data above 2 K by the
theory of weak antilocalization in two-dimensional metals and suggest that
spin-flip scatterings by magnetic impurities inside Cu are suppressed in Cu/CuO
samples. Plausibly the results imply a proximity effect of antiferromagnetism
inside the Cu layer, which can be understood in the framework of
Ruderman-Kittel-Kasuya-Yoshida (RKKY) interactions. The data below 1 K, which
exhibit slow relaxation reminiscent of spin glass, are consistent with this
interpretation.Comment: 6 pages, 4 figures, 2 tables. Added a supplementary materia
Evidence for the disky origin of luminous Virgo dwarf ellipticals from the kinematics of their globular cluster systems
We report evidence for dynamically significant rotation in the globular
cluster systems of two luminous Virgo dwarf ellipticals, VCC1261 and VCC1528.
Including previous results for VCC1087, the globular cluster systems of all
three Virgo dwarf ellipticals studied in detail to date exhibit v_rot/sigma >
1. Taking the rotation seen in the globular clusters as maximal disk rotation,
we find all three dEs lie on the r-band Tully-Fisher relation. We argue that
these data support the hypothesis that luminous dEs are the remnants of
transformed disk galaxies. We also obtained deep, longslit data for the stars
in VCC1261 and VCC1528. Both these galaxies show rapid rotation in their inner
regions, with spatial scales of ~0.5 kpc. These rotation velocities are similar
to those seen in the GC systems. Since our longslit data for Virgo dEs extend
out to 1-2 effective radii (typical of deep observations), whereas the globular
clusters extend out to 4--7 effective radii, we conclude that non-detections of
rotation in many luminous dEs may simply be due to a lack of radial coverage in
the stellar data, and that globular clusters represent singularly sensitive
probes of the dynamics of dEs. Based on these data, we suggest that gas disks
are significant sites of globular cluster formation in the early universe.Comment: To appear in the AJ, corrected typographical errors in Table 1, added
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