The Propagation of a Liquid Bolus Through an Elastic Tube and Airway Reopening

We use lubrication theory and matched asymptotic expansions to model the quasi-steady propagation of a liquid bridge through an elastic tube. In the limit of small capillary number, asymptotic expressions are found for the pressure drop across the bridge and the thickness of the liquid film left behind, as functions of the capillary number, the thickness of the liquid lining ahead of the bridge and the elastic characteristics of the tube wall. For a given precursor thickness, we find a critical propagation speed, and hence a critical imposed pressure drop, above which the bridge will eventually burst, and hence the tube will reopen

Threshold-Concept inspired eTutorials in electronics

Engagement of students in traditional engineering tutorials can be low, especially where the level of preparation varies widely across the student population. Online tutorials are a way of addressing this problem, as they offer the chance for students to work at their own pace, at their own preferred times, while staff can add and update questions, links, and hints in almost-real time. We created such a set of tutorials in an introductory electronics course, incorporating a strong Threshold-Concept focus. The tutorials were coded by one of us (Balsom) in PHP, and this allowed us to extensively and flexibly control reporting to examine student usage. We benchmarked students from year to year, introduced the eTutorials, and measured their impact. We employed surveys and interviews for additional feedback. We quantitatively and qualitatively address the question of how effective the eTutorials were in comparison with well-staffed, well-attended, conventional tutorials addressing the exact same material in the previous year. We also search for correlations between student usage and eventual grade with the aim of early detection of students requiring intervention. The cost is compared with use of commercially-available eTutorials in Physics that are used by a parallel introductory Physics course in the same school

Characterizing the Variability of Stars with Early-release Kepler Data

We present a variability analysis of the early-release first quarter of data publicly released by the Kepler project. Using the stellar parameters from the Kepler Input Catalog, we have separated the sample into 129,000 dwarfs and 17,000 giants and further sub-divided the luminosity classes into temperature bins corresponding approximately to the spectral classes A, F, G, K, and M. Utilizing the inherent sampling and time baseline of the public data set (30 minute sampling and 33.5 day baseline), we have explored the variability of the stellar sample. The overall variability rate of the dwarfs is 25% for the entire sample, but can reach 100% for the brightest groups of stars in the sample. G dwarfs are found to be the most stable with a dispersion floor of σ ~ 0.04 mmag. At the precision of Kepler, >95% of the giant stars are variable with a noise floor of ~0.1 mmag, 0.3 mmag, and 10 mmag for the G giants, K giants, and M giants, respectively. The photometric dispersion of the giants is consistent with acoustic variations of the photosphere; the photometrically derived predicted radial velocity distribution for the K giants is in agreement with the measured radial velocity distribution. We have also briefly explored the variability fraction as a function of data set baseline (1-33 days), at the native 30 minute sampling of the public Kepler data. To within the limitations of the data, we find that the overall variability fractions increase as the data set baseline is increased from 1 day to 33 days, in particular for the most variable stars. The lower mass M dwarf, K dwarf, and G dwarf stars increase their variability more significantly than the higher mass F dwarf and A dwarf stars as the time baseline is increased, indicating that the variability of the lower mass stars is mostly characterized by timescales of weeks while the variability of the higher mass stars is mostly characterized by timescales of days. A study of the distribution of the variability as a function of galactic latitude suggests that sources closer to the galactic plane are more variable. This may be the result of sampling differing populations (i.e., ages) as a function of latitude or may be the result of higher background contamination that is inflating the variability fractions at lower latitudes. A comparison of the M dwarf statistics to the variability of 29 known bright M dwarfs indicates that the M dwarfs are primarily variable on timescales of weeks or longer presumably dominated by spots and binarity. On shorter timescales of hours, which are relevant for planetary transit detection, the stars are significantly less variable, with ~80% having 12 hr dispersions of 0.5 mmag or less

Teacher Candidates’ Emerging Perspectives on Trauma Informed Teaching

A transdisciplinary team of candidates with teacher and social work educators describe their perspectives of trauma-informed teaching and intentions to use evidence-based practices in classrooms. We studied classroom management from a trauma-informed perspective in the first course in the program, then reflected back on these through a professional learning community created to intentionally focus on trauma informed teaching. We highlight findings around candidates’ perspectives and specific actions they attended to in order to incorporate those practices

Sorting of chromosomes by magnetic separation

Chromosomes were isolated from Chinese hamster x human hybrid cell lines containing four and nine human chromosomes. Human genomic DNA was biotinylated by nick translation and used to label the human chromosomes by in situ hybridization in suspension. Streptavidin was covalently coupled to the surface of magnetic beads and these were incubated with the hybridized chromosomes. The human chromosomes were bound to the magnetic beads through the strong biotin-streptavidin complex and then rapidly separated from nonlabeled Chinese hamster chromosomes by a simple permanent magnet. The hybridization was visualized by additional binding of avidin-FITC (fluorescein) to the unoccupied biotinylated human DNA bound to the human chromosomes. After magnetic separation, up to 98% of the individual chromosomes attached to magnetic beads were classified as human chromosomes by fluorescence microscopy

Evaluating Flipped Classrooms with respect to Threshold Concepts Learning in Undergraduate Engineering

This paper reports on the initial findings from a two year (2015-2016) investigation of the impact of the flipped classroom on student learning of threshold concepts (TCs) in a large introductory undergraduate engineering course at a New Zealand university. As part of the flipped class intervention trialed over a threeweek period, a series of short themed video lectures were developed as a replacement for the traditional weekly lectures. The weekly practical lab session were redesigned to incorporate small-group problem solving tasks and assessment. Data from student surveys, interviews, class observations, and video analytics were collected and analyzed. Findings revealed that students were familiar with online videos as a learning resource; they had positive past experiences with using them and were willing to participate in a flipped classroom. However, most students did not watch all assigned weekly videos, including ones crucial to their TC learning. There is indication they thought learning strategies involving interactions with real persons to be more useful to their learning. This suggests that current strategies for motivating students to access and engage with the prepared videos need to be revised to maximize students’ learning opportunities

Elevated Blood Lead Concentrations and Vitamin D Deficiency in Winter and Summer in Young Urban Children

BACKGROUND: It is widely recognized that blood lead concentrations are higher in the summer than in winter. Although the effects of some environmental factors such as lead in dust on this phenomenon have been studied, relationships to sunlight-induced vitamin D synthesis have not been adequately investigated. Vitamin D status is influenced by the diet, sunlight exposure, age, skin pigmentation, and other factors, and may modify gastrointestinal lead absorption or release of lead stored in bones into the bloodstream. OBJECTIVE AND METHODS: We collected paired blood samples from 142 young, urban African-American and Hispanic children in the winter and summer to study the seasonal increase in blood lead and its relationships to vitamin D nutrition, age, and race. RESULTS: A winter/summer (W/S) increase in blood lead concentrations of 32.4% was found for children 1–3 years of age. There was a smaller W/S increase of 13.0% in children 4–8 years of age. None of the 51 Hispanic children had an elevated blood lead concentration (≥ 10 μg/dL) during the winter, and only one had an elevated summertime concentration. In contrast, elevated blood lead concentrations were frequent in the 91 African-American children, especially those 1–3 years of age. For the latter, the percentage with elevated blood lead levels increased from 12.2% in winter to 22.5% in summer. A 1.2% W/S increase in serum 25-hydroxy-vitamin D (serum 25-OH-D) concentrations was found for children 1–3 years of age. However, in children 4–8 years of age the W/S increase in serum 25-OH-D was much larger—33.6%. The percentages of children with low (< 16 μg/L) serum 25-OH-D concentrations were 12.0% in winter and 0.7% in summer and were consistently greater in African-American than in Hispanic children. The seasonal increases in blood lead and serum 25-OH-D in children 4–8 years of age were significantly associated. CONCLUSION: The higher summertime serum 25-OH-D concentrations for the 4- to 8-year-old children are likely caused by increased sunlight-induced vitamin D synthesis and may contribute to the seasonal increase in blood lead. Age and race are key factors that affect blood lead and vitamin D nutrition, as well as their interactions, in young urban children

Flipped classroom learning in a first-year undergraduate engineering course

Flipped classrooms support student-centred learning and are increasingly being adopted in institutions of higher learning worldwide. This paper is a report on the findings of a two-year funded project conducted on the impact of adopting a flipped classroom approach on first-year undergraduate engineering students’ learning in a New Zealand university. A designbased methodology was adopted to allow for five iterative course refinements. Data collected through student achievement data, surveys, focus group interviews, observations and video analytics of student video-watching behaviour indicated a significant improvement in students’ learning and that they valued the flipped course components such as the lecturercreated instructional videos, in-class problem-solving exercises and continuous assessment in supporting their learning. However not all students prefer learning through this approach and more scaffolding is needed for first-year students to take up responsibility for their own learning. Implications for practice are offered

Learning threshold concepts in an undergraduate engineering flipped classroom

Given that the current goals for tertiary education is to better prepare students to apply their disciplinary knowledge in the real world and novel situations, it is imperative that students master the necessary disciplinary threshold concepts and competencies. Building on the findings of our pilot study of a partly-flipped undergraduate electronic engineering course, a version of a fully flipped is implemented in an intensive six-week version of the course involving in-class collaborative problem solving and continuous assessment. Data collected from the 32 students enrolled in the course include student surveys, video analytics, weekly student assessments, class observations and a focus group interview. Although data collection is still underway, the emerging findings indicate that students are watching the recommended weekly videos prior to coming to class and are solving online tutorials problems much more diligently, resulting in higher levels of in-class student collaboration compared to the pilot study. The results are discussed in regard to the effects of the fully flipped class model and the continuous assessment on students’ learning of threshold concepts and competencies