23,930 research outputs found
Collaborative concept mapping: an education research team leveraging their collaborative efforts
Collaborative concept mapping (CCM) has been a tool deployed by educators to enhance learning in such situations as primary science classes, supported learning environments and asynchronous computer-mediated learning. Of its outcomes, CCM has produced rich group discussion about ideas and possibilities pertinent to the topic or problem at hand. The majority of research into CCM has been explicitly pointed at enhancing learning. This chapter takes a different tack by reporting on how the authors used CCM to seek understandings of its utility in enabling collaborative research by creating synergies within a research team located in the Faculty of Education at the University of Southern Queensland. The following questions were used to focus the research:
• What was the research team’s experience of collaborative concept mapping?
• What propositions did the team construct about teamwork and collaboration?
• How did the interactions among team members facilitate meaning-making about teamwork and collaboration?
The data consisted of this team’s collaborative concept map and recordings of the dialogue during the process of constructing the map. Analysis revealed the team’s emerging propositions about teamwork and collaboration and also contributed understandings of the co-constructed patterns of talk that produced this dynamic map. The chapter concludes that collaborative concept mapping is a useful tool for research and other team development, and possibly for the collaborative conceptualisation of future team research projects
Application of numerical methods to planetary radiowave scattering
Existing numerical techniques for the solution of scattering problems were investigated to determine those which might be applicable to planetary surface studies, with the goal of improving the interpretation of radar data from Venus, Mars, the Moon, and icy satellites. The general characteristics of the models are described along with computational concerns. In particular, the Numerical Electrogmatics Code (NEC) developed at the Lawrence Livermore Laboratory is discussed. Though not developed for random rough surfaces, the NEC contains elements which may be generalized and which could be valuable in the study of scattering by planetary surfaces
Surface properties of Galilean satellites from bistatic radar experiments
The icy moons of Jupiter were the first to show unusual radar backscatter behavior in Earth-based experiments. Studies of Europa, Ganymede, and Callisto revealed strong echoes and a reversed sense of circular polarization. No explanations were entirely satisfactory because of the difficult constraints imposed by the existing data. The (scalar) bidirectional coherence model predicts an opposition effect, or enhancement in the backscatter direction, resulting from coherent addition of backscatter from identical (but oppositely directed) ray paths. The mode decoupling model yields a similar, vector result in which the observed polarization properties of the backscattered wave can also be obtained. The possibilities were considered for conducting such experiments using the Galileo spacecraft. Both conventional oblique-forward bistatic experiments (to determine basic electrical and physical properties of the surface material on centimeter-meter scales) and near-backscatter experiments (to sample the enhanced backscatter lobe) were considered
Asymmetries of Heavy Elements in the Young Supernova Remnant Cassiopeia A
Supernova remnants (SNRs) offer the means to study supernovae (SNe) long
after the original explosion and can provide a unique insight into the
mechanism that governs these energetic events. In this work, we examine the
morphologies of X-ray emission from different elements found in the youngest
known core-collapse (CC) SNR in the Milky Way, Cassiopeia A. The heaviest
elements exhibit the highest levels of asymmetry, which we relate to the
burning process that created the elements and their proximity to the center of
explosion. Our findings support recent model predictions that the material
closest to the source of explosion will reflect the asymmetries inherent to the
SN mechanism. Additionally, we find that the heaviest elements are moving more
directly opposed to the neutron star (NS) than the lighter elements. This
result is consistent with NS kicks arising from ejecta asymmetries.Comment: 12 pages, 4 figures, 2 tables Updated to include an analysis of
Emission Measure Maps (vs the, still-included, continuum-subtracted flux
maps), used as another proxy for mass maps. The results have not changed; the
emission measure maps also show increasing asymmetry with ejecta mass. (Now
matches the version published in ApJ. Vol 889 Issue 2 (2020) 144
Torque control system
System stabilizes aximuth of gondolas which are carried by high-altitude balloons as platforms for tracking telescopes. When telescopes must be constantly aimed at specific targets, control system stabilizes gondola to within 5 arc-seconds
Subcentimeter-size particle distribution functions in planetary rings from Voyager radio and photopolarimeter occultation data
Analysis of measurements of the scattered and direct components of Voyager 1 radio occultation signals at 3.5 and 13 cm wavelengths yield estimates of the distribution functions of supracentimeter-size particles and thickness of relatively broad regions in Saturn's rings. If mearurements of signal amplitude at a shorter wavelength are combined with the previously analyzed data, the shape of the distribution functions characterizing the smaller particles can be constrained. If size distributions of arbitrary form were considered, many solutions are found that are consistent with the three available observations of signal amplitude. The best-fit power law was calculated to the three observations at three wavelengths for several of the embedded Saturn ringlets. Mie scattering theory predicts that the measured phase of the radio occultation signal is highly sensitive to particles ranging from 0.1 to 1.0 wavelengths in size, thus additional constraints on the subcentimeter-size distribution functions for both the Saturn and Uranus rings can in principle be derived from radio phase measurements
Automatic analysis of Swift-XRT data
The Swift spacecraft detects and autonomously observes ~100 Gamma Ray Bursts
(GRBs) per year, ~96% of which are detected by the X-ray telescope (XRT). GRBs
are accompanied by optical transients and the field of ground-based follow-up
of GRBs has expanded significantly over the last few years, with rapid response
instruments capable of responding to Swift triggers on timescales of minutes.
To make the most efficient use of limited telescope time, follow-up astronomers
need accurate positions of GRBs as soon as possible after the trigger.
Additionally, information such as the X-ray light curve, is of interest when
considering observing strategy. The Swift team at Leicester University have
developed techniques to improve the accuracy of the GRB positions available
from the XRT, and to produce science-grade X-ray light curves of GRBs. These
techniques are fully automated, and are executed as soon as data are available.Comment: 4 pages, 2 figures, to appear in the proceedings of ADASS XVII (ASP
Conference Series
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