The TeCTra online groupwork tool: Scaffolding the learning of self and peer assessment

A reliable assessment strategy for allocating different summative marks for individual contributions in groupwork is a perennial problem that using the TeCTra online tool can resolve. By collecting weekly quantitative and qualitative data to support the individualising of contributions and summative marks the tool supports and scaffolds the studentsâ learning of self and peer assessment understandings, knowledge and skills. This paper discusses the changing design of peer assessment from 1998 to 2008 and the impact of the TeCTRa groupwork tool within a capstone undergraduate subject with large student numbers at UTS. The TeCTra strategy has delivered more diversity of individual summative marks than those reported in the literature and experienced by the authors in the period before the introduction of the tool in 2004. The system for calculating an individual contribution factor has released the academic from the enormous workload otherwise required to process any similar paper-based strategy

Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: Revealing the inner funnel of dust

We present new interferometric data obtained with MIDI (MID infrared Interferometric instrument) for the Seyfert II galaxy NGC 1068, with an extensive coverage of sixteen uv points. These observations resolve the nuclear mid-infrared emission from NGC 1068 in unprecedented detail with a maximum resolution of 7 mas. For the first time, sufficient uv points have been obtained, allowing us to generate an image of the source using maximum entropy image reconstruction. The features of the image are similar to those obtained by modelling. We find that the mid-infrared emission can be represented by two components, each with a Gaussian brightness distribution. The first, identified as the inner funnel of the obscuring torus, is hot (800K), 1.35 parsec long, and 0.45 parsec thick in FWHM at a PA=-42 degrees (from north to east). It has an absorption profile different than standard interstellar dust and with evidence for clumpiness. The second component is 3 by 4 pc in FWHM with T=300K, and we identify it with the cooler body of the torus. The compact component is tilted by 45 degrees with respect to the radio jet and has similar size and orientation to the observed water maser distribution. We show how the dust distribution relates to other observables within a few parsecs of the core of the galaxy such as the nuclear masers, the radio jet, and the ionization cone. We compare our findings to a similar study of the Circinus galaxy and other relevant studies. Our findings shed new light on the relation between the different parsec-scale components in NGC 1068 and the obscuring torus.Comment: Accepted to MNRA

Experimental Investigation of the Subjective Value of Information in Trading

Subjective judgments regarding information are important for the design of information systems. This study examines the endowment effect in the context of evaluating information. Theoretically, value judgments that affect the demand for information are influenced by ownership rights, a phenomenon known as the endowment effect in trading situations. In a simple computer simulated business game, 31 participants conducted a management task in which they were provided opportunities to buy or sell information. The bidding mechanism was incentive compatible. Results show that, in agreement with endowment effect theory, people value information they own much more than information they do not own. This portends undertrading in information. Therefore, the subjective value of information should be considered in the design of systems. Our findings indicate a place for the subjective value of information on the WTA/WTP ratio continuum that emerges from pertinent literature. The ratio for information is similar to that of market goods. Participants had a strong inclination to purchase but not to sell information even though the profit data suggests that the use of information had no objective benefit. This preference is attributed to risk aversion rather than to loss aversion, which is the most widely accepted explanation of the endowment effect. The subjective value of information can, therefore, be affected by system design

The Subjective Value of Information: Trading expertise vs. content, copies vs. originals in E-Business

What is the subjective value assigned to information? Is the subjective value of information similar to the realistic or normative value, or are there deviations introduced by human processing, the framing of the information source, or the external qualities of packaging and ownership of the information? Do people assess information as having the same value when offered the chance to sell it (Willingness to Accept, WTA) as when facing the need to buy it (Willingness to Purchase, WTP)? This is an empirical, experimental investigation of the effects of expertise vs. content, and copy vs. exclusive original packaging of information on the WTA/WTP ratio. In an animated computer simulation of a business game players maximize their profits by making choices regarding inventory and prices. Participants were also offered the chance to bid in trade (buy or sell) information regarding the weather that may affect demand. We find, as hypothesized, that the subjective value of information does indeed follow the predictions of Endowment Effect theory. Participants revealed a ratio of Willingness to Accept to Willingness to Purchase (WTA/WTP) that resembles the ratio common in the case of private goods. In the decisions, choices and performance recorded for the 294 subjects, we also found support for the hypothesis that the WTA/WTP diverges from unity more often and in a more pronounced manner for information traded in the “original” form rather than as a copy of the original, although even for copies the WTA/WTP ratio is still double. Results yield a value of about three for the WTA/WTP ratio for original information regardless of whether the source is content or expertise. Valuations of content and expertise did not diverge. However, the source of information can be manipulated by system design to become more salient. Copy information received a subjective value which was significantly different (lower) than original information. Implications for both online trading and online sharing of information are discussed

Tailoring competitive information sources to the sequence of dynamic capabilities

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Tailoring a Points Scoring Mechanism for Crowd-Based Knowledge Pooling

We address the design of point scoring mechanisms in games for crowds, to promote user motivations to contribute knowledge. We measure the effectiveness of the scoring mechanism on users’ performance across three types of crowd: general public, students in their field of study, general students. The conditions were: reward-free games (control group) and two reward-based systems differing in the algorithm applied (linear y=3x vs. exponential y=6ex). Results support the importance of the mathematical function of scores assignment as a motivator for knowledge contribution, and indicate that the effect of the scoring mechanism design should be tailored according to the type of crowd. These findings provide insights for designers of gamified systems on how to improve knowledge contributions in crowd-based systems

Advancing the m-learning research agenda for active, experiential learning: Four case studies

This article reports on an m-learning research agenda instituted at our university in order to explore how mobile technology can enhance active, experiential learning. Details of the implementation and results of four areas of m-learning are presented: mobile supported fieldwork, fostering interactivity in large lectures with mobile technology, using mobile devices to learn about mobile technology and, finally, podcasting. These directions are informed by a concern for achieving m-learning practices consistent with sound educational theory and the needs of the contemporary, technologically aware student body. All four implementations have been successfully embedded in mainstream subjects on a continuing basis. Therefore they represent a departure from the project based approach of much m-learning reported in the literature. This outcome was achieved through a focus on the economic sustainability and feasibility of each case. An evaluation focusing on how well each case assisted students' learning found that, with the exception of lecture podcasting, all supported high quality experiential learning

Resolving the nucleus of Centaurus A at mid-IR wavelengths

We have observed Centaurus A with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) at resolutions of 7 - 15 mas (at 12.5 micron) and filled gaps in the (u,v) coverage in comparison to earlier measurements. We are now able to describe the nuclear emission in terms of geometric components and derive their parameters by fitting models to the interferometric data. With simple geometrical models, the best fit is achieved for an elongated disk with flat intensity profile with diameter 76 +/- 9 mas x 35 +/- 2 mas (1.41 +/- 0.17 pc x 0.65 +/- 0.03 pc) whose major axis is oriented at a position angle (PA) of 10.1 +/- 2.2 degrees east of north. A point source contributes 47 +/- 11 % of the nuclear emission at 12.5 micron. There is also evidence that neither such a uniform nor a Gaussian disk are good fits to the data. This indicates that we are resolving more complicated small-scale structure in AGNs with MIDI, as has been seen in Seyfert galaxies previously observed with MIDI. The PA and inferred inclination i = 62.6 +2.1/-2.6 degrees of the dust emission are compared with observations of gas and dust at larger scales.Comment: Accepted for the PASA special issue on Centaurus

Dust emission from a parsec-scale structure in the Seyfert 1 nucleus of NGC 4151

We report mid-IR interferometric measurements with \sim 10 mas resolution, which resolve the warm (T = 285 +25 / -50 K) thermal emission at the center of NGC 4151. Using pairs of VLT 8.2 m telescopes with MIDI and by comparing the data to a Gaussian model, we determined the diameter of the dust emission region, albeit only along one position angle, to be 2.0 +/- 0.4 pc (FWHM). This is the first size and temperature estimate for the nuclear warm dust distribution in a Seyfert 1 galaxy. The parameters found are comparable to those in Seyfert 2 galaxies, thus providing direct support for the unified model. Using simple analytic temperature distributions, we find that the mid-infrared emission is probably not the smooth continuation of the hot nuclear source that is marginally resolved with K band interferometry. We also detected weak excess emission around 10.5 micron in our shorter baseline observation, possibly indicating that silicate emission is extended to the parsec scale.Comment: 5 pages, 4 figures, accepted for publication in The Astrophysical Journal Letter