Improving the viability of mental models held by novice programmers

Recent research has found that many novice programmers often hold non-viable mental models of basic programming concepts such as assignment and object reference. This paper proposes a constructivist-based teaching model, integrating a cognitive conflict strategy with program visualization, with the aim of improving novice programmers’ mental models. The results of a preliminary empirical study suggest that, for the relatively straightforward concept of assignment, tight integration of program visualization with a cognitive conflict event that highlights a student’s inappropriate understanding can help improve students’ non-viable mental models. 14 out of 18 participants who held non-viable mental models of the assignment process successfully changed their model to be viable as a result of the proposed teaching model

Biological implications of a discrete mathematical model for collagen deposition and alignment in dermal wound repair

We deveiop a novel mathematical model for collagen deposition and alignment during dermal wound healing. We focus on the interactions between fibroblasts, modelled as discrete entities, and a continuous extracellular matrix composed of collagen and a fibrin based blood clot. There are four basic interactions assumed in the model: fibroblasts orient the collagen matrix, fibroblasts produce and degrade collagen and fibrin and the matrix directs the fibroblasts and determines the speed of the cells. Several factors which influence the alignment of collagen are examined and related to current anti-scarring therapies using transforming growth factor ß. The most influential of these factors are cell speed and, more importantly for wound healing, the influx of fibroblasts from surrounding tissue

MGGPOD: a Monte Carlo Suite for Modeling Instrumental Line and Continuum Backgrounds in Gamma-Ray Astronomy

Intense and complex instrumental backgrounds, against which the much smaller signals from celestial sources have to be discerned, are a notorious problem for low and intermediate energy gamma-ray astronomy (~50 keV - 10 MeV). Therefore a detailed qualitative and quantitative understanding of instrumental line and continuum backgrounds is crucial for most stages of gamma-ray astronomy missions, ranging from the design and development of new instrumentation through performance prediction to data reduction. We have developed MGGPOD, a user-friendly suite of Monte Carlo codes built around the widely used GEANT (Version 3.21) package, to simulate ab initio the physical processes relevant for the production of instrumental backgrounds. These include the build-up and delayed decay of radioactive isotopes as well as the prompt de-excitation of excited nuclei, both of which give rise to a plethora of instrumental gamma-ray background lines in addition to continuum backgrounds. The MGGPOD package and documentation are publicly available for download from http://sigma-2.cesr.fr/spi/MGGPOD/. We demonstrate the capabilities of the MGGPOD suite by modeling high resolution gamma-ray spectra recorded by the Transient Gamma-Ray Spectrometer (TGRS) on board Wind during 1995. The TGRS is a Ge spectrometer operating in the 40 keV to 8 MeV range. Due to its fine energy resolution, these spectra reveal the complex instrumental background in formidable detail, particularly the many prompt and delayed gamma-ray lines. We evaluate the successes and failures of the MGGPOD package in reproducing TGRS data, and provide identifications for the numerous instrumental lines.Comment: 60 pages, 13 figures, 7 tables, accepted for publication in ApJ

The Spectacular Ionized Interstellar Medium of NGC55

We present deep Halpha+[NII], [SII] (6716,6731A) and [OII] (3726,3729A) images of the highly inclined, actively star--forming SBm galaxy NGC 55, located in the nearby Sculptor Group. Due to its proximity, NGC 55 provides a unique opportunity to study the disk--halo interface in a late--type galaxy with unprecedented spatial resolution. Our images reveal a spectacular variety of ionized gas features, ranging from giant HII region complexes, to supergiant filamentary and shell features, to patches of very faint diffuse emission. Many of these features protrude well above the plane of the galaxy, including a very faint fragmented shell of emission which is visible at 2.6 kpc above the disk. We identify candidate `chimneys' extending out of the disk, which could be the conduits into the halo for hot gas around disk star-forming regions, and could also provide low-density paths for the passage of UV photons from the disk to the halo. Several of the identified chimneys are `capped' with clumps of ionized gas, one of which, located at 1.5 kpc above the disk plane, appears to be the site of recent star formation. Emission--line ratios ([OII]/Halpha+[NII], [SII]/Halpha+[NII]) constrain the ionization mechanism of the gas, and our images allow the first measurement of [OII]/Halpha+[NII] in extra-planar diffuse ionized gas. The diffuse gas is characterized by emission--line ratios which are enhanced on average by a factor of two compared to those of bright HII regions. Each line ratio increases in value smoothly from the cores of HII regions, through the haloes of HII regions, into the diffuse ionized gas. Such a continuous trend is predicted by models in which the diffuse gas is ionized by photons produced by massive stars in HII regions.Comment: 19 pages, including 4 figures, plus 2 external tables. Accepted for publication in the Astronomical Journal. Compressed, postscript versions of the plates are available at ftp://skysrv.pha.jhu.edu/ferguson

Using Serious Games for Learning British Sign Language Combining Video, Enhanced Interactivity, and VR Technology

One in every six persons in the UK suffers a hearing loss, either as a condition they have been born with or they disordered they acquired during their life. 900,000 people in the UK are severely or profoundly deaf and based on a study by Action On Hearing Loss UK in 2013 only 17 percent of this population, can use the British Sign Language (BSL). That leaves a massive proportion of people with a hearing impediment who do not use sign language struggling in social interaction and suffering from emotional distress, and an even larger proportion of Hearing people who cannot communicate with those of the deaf community. This paper presents a serious game (SG) that aims to close the communication gap between able hearing people and people with a hearing impediment by providing a tool that facilitates BSL learning targeting adult population. The paper presents the theoretical framework supporting adult learning based on which a SG game using Virtual Reality (VR) technology has been developed. It explains the experimental framework of the study and presents the creation of the research instruments to facilitate the study comprising of a SG that integrates video and conventional video based educational material. It reports and analyses the study results that demonstrate the advantage of the SG in effectively supporting users learning a set of BSL signs and it presents qualitative outcomes that inform the further development of the game to serve learning needs. The paper closes with conclusions, directions for further development of this educational resource and future studies

Structural templating as a route to improved photovoltaic performance in copper phthalocyanine/fullerene (C60) heterojunctions

We have developed a method to improve the short circuit current density in copper phthalocyanine (CuPc)/fullerene (C60) organic solar cells by ~60% by modifying the CuPc crystal orientation through use of a molecular interlayer to maximize charge transport in the direction between the two electrodes. Powder x-ray diffraction and electronic absorption spectroscopy show that a thin 3,4,9,10-perylenetetracarboxylic dianhydride interlayer before CuPc growth templates the CuPc film structure, forcing the molecules to lie flat with respect to the substrate surface, although the intrastack orientation is unaffected. This modified stacking configuration facilitates charge transport and improves charge collection