Communities in university mathematics

This paper concerns communities of learners and teachers that are formed, develop and interact in university mathematics environments through the theoretical lens of Communities of Practice. From this perspective, learning is described as a process of participation and reification in a community in which individuals belong and form their identity through engagement, imagination and alignment. In addition, when inquiry is considered as a fundamental mode of participation, through critical alignment, the community becomes a Community of Inquiry. We discuss these theoretical underpinnings with examples of their application in research in university mathematics education and, in more detail, in two Research Cases which focus on mathematics students' and teachers' perspectives on proof and on engineering students' conceptual understanding of mathematics. The paper concludes with a critical reflection on the theorising of the role of communities in university level teaching and learning and a consideration of ways forward for future research

The paracaspase MALT1: biological function and potential for therapeutic inhibition.

The paracaspase MALT1 has a central role in the activation of lymphocytes and other immune cells including myeloid cells, mast cells and NK cells. MALT1 activity is required not only for the immune response, but also for the development of natural Treg cells that keep the immune response in check. Exaggerated MALT1 activity has been associated with the development of lymphoid malignancies, and recently developed MALT1 inhibitors show promising anti-tumor effects in xenograft models of diffuse large B cell lymphoma. In this review, we provide an overview of the present understanding of MALT1's function, and discuss possibilities for its therapeutic targeting based on recently developed inhibitors and animal models

Self-sterilization of bodies during outer planet entry

A body encountering the atmosphere of an outer planet is subjected to heat loads which could result in high temperature conditions that render terrestrial organisms on or within the body nonviable. To determine whether an irregularly shaped entering body, consisting of several different materials, would be sterilized during inadvertent entry at high velocity, the thermal response of a typical outer planet spacecraft instrument was studied. The results indicate that the Teflon insulated cable and electronic circuit boards may not experience sterilizing temperatures during a Jupiter, Saturn, or Titan entry. Another conclusion of the study is that small plastic particles entering Saturn from outer space have wider survival corridors than do those at Jupiter

A Naturalistic Study of Long-term Working Memory Capacity for Meaningful Visual and Auditory Stimuli

The purpose of this study was to explore long-term working memory in experts in an information-rich, dynamic domain. Of particular interest were strategies experts use to enhance long-term working memory capacity when working with verbal versus aural information. Three air traffic control instructors participated in four complex air traffic control scenarios, two radar scenarios in which information was presented visually and two non-radar scenarios in which information presentation was purely aural. Participants recalled traffic situation information at two points during and at the end of each scenario. Recall data for each scenario type were assessed in terms of evidence about information chunking and organizational strategies, the role of long-term working memory in extending working memory capacity, and the format of traffic situation information held in long-term working memory. Patterns of recall were consistent with template-based explanations of information organization and the use of information chunking within templates. Data were consistent with Ericsson and Kintsch\u27s (1995) model of long-term working memory in that working memory capacity seemed to be extended by the storing of traffic situation information in long-term working memory templates from which it seemed to be selectively and readily accessed and brought into working memory. Traffic situation information tended to be recalled in different orders for radar compared with non-radar scenarios, although the general organizational structure of the information seemed similar. Information, regardless of whether presented visually or aurally, tended to be recalled based on aircraft position, which seemed to prime other aircraft attributes which, in turn, seemed to prime yet other aircraft attributes. The results of this research have the potential to contribute to the long-term working memory, working memory, and expertise literatures. For example, they suggest hypotheses about expert and novice long-term working memory capacity that could be pursued in future research. To this end, the present study will be replicated using novice air traffic controllers. The comparison of novice and expert recall patterns has the potential to shed light on differences in information storage and recall strategies and could have implications for training air traffic controllers. The study additionally could hold implications for the design of NextGen air traffic control products and systems in other complex work domains. These results could shed light on display design for those systems by suggesting which information can or should be displayed within an aircraft\u27s data tag and which can or should be presented aurally

Nucleus Pulposus of the Intervertebral Disc: The Effect of Environmental Factors on Metabolic Activity

Lower back pain is a major socioeconomic concern in developed nations. Moreover, it is a condition which a majority of people will experience an episode within their lifetime, with a portion becoming chronically afflicted. Degeneration of the intervertebral disc (IVD) is believed to play a critical role in initiating lower back pain. Poor nutrient supplies are implicated as a one of the root causes of this degeneration and much effort has been spent to better elucidate the behavior of IVD cells. The IVD is the largest avascular structure within the body, relying on diffusion to migrate nutrients in and clear wastes out. Due to this limitation, nutrients concentrations are low within the center of the disc and waste products also accumulate in high concentrations. For most cell niches, this is considered a harsh environment, but completely normal for the cells of the IVD. Understanding how these cells behave under these environmental conditions may elucidate what nutritional and environmental factors lead to aberrant IVD cell behavior. This dissertation will explore the relationship between nutrient conditions and the metabolic adaptations of the IVD cells. Additionally, a custom bioreactor was constructed in order to study the complex IVD organ as a whole under varied nutritional conditions. Glucose consumption rate and gene expression of nucleus pulposus (NP) cells was investigated in an agarose gel system over prolonged culture periods with varied oxygen tension and glucose concentration treatments. Glucose consumption rate was found to decrease with increasing oxygen tension and over time but not with changing glucose concentration. Catabolic gene expression increased for all groups over time, with inhibitors of catabolism following suit. Collagen Type I increased in expression with time for the high oxygen tensions while other anabolic genes did not show any consistent trends over the culture period. The optimal reference genes were evaluated and the genes RPL4 and YWHAZ were found to be more stable than the commonly used 18s and GAPDH. Next the glucose consumption rate was modeled using a more sophisticated method, the Michalis-Menten kinetic model, allowing for increased fidelity in computational modeling and optimizing culture conditions. No differences between oxygen tension were found in the GCR. Gene expression was again analyzed but the limited culture time did not allow for differences to be seen between oxygen tensions. A correlational analysis revealed several targets for further genetic studies. A custom-built bioreactor was developed and validated to load whole IVD under simulated physiological loading conditions. This reactor was then used to test whole IVDs under free-swelling and dynamic loading conditions. Tissues were compared for their gross composition as well as gene expression differences. No differences were seen between loaded and free-swelling discs, and both tended toward a catabolic state when examining gene expression. Gross changes in tissue composition were seen briefly in hydroxyproline content before returning to baseline. The contents of this dissertation greatly enhance the knowledge of IVD NP cell metabolism. Given that these cells play a vital role in disc degeneration and will be critical in regenerative strategies to treat said condition, understanding the behavior of these critical cells is of paramount importanc

Surface losses and self-pumping effects in a long Josephson junction - a semi-analytical approach

The flux-flow dynamics in a long Josephson junction is studied both analytically and numerically. A realistic model of the junction is considered by taking into account a nonuniform current distribution, surface losses and self-pumping effects. An approximate analytical solution of the modified sine-Gordon equation is derived in the form of a unidirectional dense fluxon train accompanied by two oppositely directed plasma waves. Next, some macroscopic time-averaged quantities are calculated making possible to evaluate the current-voltage characteristic of the junction. The results obtained by the present method are compared with direct numerical simulations both for the current-voltage characteristics and for the loss factor modulated spatially due to the self-pumping. The comparison shows very good agreement for typical junction parameters but indicates also some limitations of the method.Comment: 7 pages, 5 figure

Unattended network operations technology assessment study. Technical support for defining advanced satellite systems concepts

The results are summarized of an unattended network operations technology assessment study for the Space Exploration Initiative (SEI). The scope of the work included: (1) identified possible enhancements due to the proposed Mars communications network; (2) identified network operations on Mars; (3) performed a technology assessment of possible supporting technologies based on current and future approaches to network operations; and (4) developed a plan for the testing and development of these technologies. The most important results obtained are as follows: (1) addition of a third Mars Relay Satellite (MRS) and MRS cross link capabilities will enhance the network's fault tolerance capabilities through improved connectivity; (2) network functions can be divided into the six basic ISO network functional groups; (3) distributed artificial intelligence technologies will augment more traditional network management technologies to form the technological infrastructure of a virtually unattended network; and (4) a great effort is required to bring the current network technology levels for manned space communications up to the level needed for an automated fault tolerance Mars communications network