794 research outputs found

    Overcoming Language Dichotomies: Toward Effective Program Comprehension for Mobile App Development

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    Mobile devices and platforms have become an established target for modern software developers due to performant hardware and a large and growing user base numbering in the billions. Despite their popularity, the software development process for mobile apps comes with a set of unique, domain-specific challenges rooted in program comprehension. Many of these challenges stem from developer difficulties in reasoning about different representations of a program, a phenomenon we define as a "language dichotomy". In this paper, we reflect upon the various language dichotomies that contribute to open problems in program comprehension and development for mobile apps. Furthermore, to help guide the research community towards effective solutions for these problems, we provide a roadmap of directions for future work.Comment: Invited Keynote Paper for the 26th IEEE/ACM International Conference on Program Comprehension (ICPC'18

    Identifying Characteristics of Effective Small Group Learning Valued by Medical Students and Facilitators

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    Background: Small group teaching is an important part of undergraduate medical education, providing the ideal setting for learners to clarify misunderstandings, test hypotheses and evaluate ideas. Many schools undergoing curriculum reform have increased the time students spend in small group learning. However, there is an overall paucity of literature examining case-based small group sessions in medical school. Objective: This study was designed to examine student and facilitator perceptions of effective case-based small group teaching in the pre-clinical years and compare results in order to identify similarities and differences and identify key areas of disconnect so that the small group learning experience can be improved. Methods: An 18-item survey was emailed to all 388 students who had started the second year of medical school at the University of Massachusetts between August 2008 and August 2010 and to 146 of 161 facilitators who had facilitated a case-based small group session during that same time. Chi-square tests of equality of proportions were used to compare the answers of students and small group facilitators. Results: 79 (54%) small group facilitators and 195 (50%) students responded. Student and facilitator responses were similar in the areas regarding goals of small group sessions and responsibilities of the facilitator. Significant difference was noted between cohorts about the most important roles of the facilitator, whether facilitators and/or students should attend training prior to sessions, whether groups should follow a consistent format, how students should be expected to prepare for small groups, how student knowledge and performance should be assessed, and whether the small group leader should be a skilled facilitator or content expert. Conclusions: This study demonstrates that there are areas where perceptions of effectiveness differ between students and facilitators. Identifying these areas presents an opportunity to make small group sessions more effective by allowing for more informed facilitator development and better communication of session expectations to students. The lack of a substantive body of literature on this important trend in medical education, coupled with our findings, suggests that further study is needed to identify characteristics of case-based small group learning that are mutually valued by students and facilitators. This will encourage the development of small group sessions that are deemed effective and maximize learning and teaching time

    Structure of the Cytoplasmic Loop between Putative Helices II and III of the Mannitol Permease of Escherichia coli: A Tryptophan and 5-Fluorotryptophan Spectroscopy Study

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    In this work, four single tryptophan (Trp) mutants of the dimeric mannitol transporter of Escherichia coli, EIImtl, are characterized using Trp and 5-fluoroTrp (5-FTrp) fluorescence spectroscopy. The four positions, 97, 114, 126, and 133, are located in a region shown by recent studies to be involved in the mannitol translocation process. To spectroscopically distinguish between the Trp positions in each subunit of dimeric EIImtl, 5-FTrp was biosynthetically incorporated because of its much simpler photophysics compared to those of Trp. The steady-state and time-resolved fluorescence methodologies used point out that all four positions are in structured environments, both in the absence and in the presence of a saturating concentration of mannitol. The fluorescence decay of all 5-FTrp-containing mutants was highly homogeneous, suggesting similar microenvironments for both probes per dimer. However, Stern-Volmer quenching experiments using potassium iodide indicate different solvent accessibilities for the two probes at positions 97 and 133. A 5 Å two-dimensional (2D) projection map of the membrane-embedded IICmtl dimer showing 2-fold symmetry is available. The results of this work are in better agreement with a 7 Å projection map from a single 2D crystal on which no symmetry was imposed.

    Old lineage on an old island : Pixibinthus, a new cricket genus endemic to New Caledonia shed light on gryllid diversification in a hotspot of biodiversity

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    Few studies have focused on the early colonization of New Caledonia by insects, after the re-emergence of the main island, 37 Myr ago. Here we investigate the mode and tempo of evolution of a new endemic cricket genus, Pixibinthus, recently discovered in southern New Caledonia. First we formally describe this new monotypic genus found exclusively in the open shrubby vegetation on metalliferous soils, named 'maquis minier', unique to New Caledonia. We then reconstruct a dated molecular phylogeny based on five mitochondrial and four nuclear loci in order to establish relationships of Pixibinthus within Eneopterinae crickets. Pixibinthus is recovered as thesister clade of the endemic genus Agnotecous, mostly rainforest-dwellers. Dating results show that the island colonization by their common ancestor occurred around 34.7 Myr, shortly after New Caledonia re-emergence. Pixibinthus and Agnotecous are then one of the oldest insect lineages documented so far for New Caledonia. This discovery highlights for the first time two clear-cut ecological specializations between sister clades, as Agnotecous is mainly found in rainforests with 19 species, whereas Pixibinthus is found in open habitats with a single documented species. The preference of Pixibinthus for open habitats and of Agnotecous for forest habitats nicely fits an acoustic specialization, either explained by differences in body size or in acoustic properties of their respective habitats. We hypothesize that landscape dynamics, linked to major past climatic events and recent change in fire regimes are possible causes for both present-day low diversity and rarity in genus Pixibinthus. The unique evolutionary history of this old New Caledonian lineage stresses the importance to increase our knowledge on the faunal biodiversity of 'maquis minier', in order to better understand the origin and past dynamics of New Caledonian biota
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