Using example generation to explore undergraduates conceptions of real sequences: a phenomenographic study

This thesis uses an example generation task to explore undergraduate students' understanding of basic sequence properties in Real Analysis. First, a review of the literature looks at three areas of research: the transition to studying mathematics at the tertiary level, examples and the process of example generation, and the learning of Real Analysis. It notes a lack of research on how students interact with simpler de nitions in Analysis, and suggests that an example generation task is an ideal research tool for this purpose. Then, two pilot studies are reported. The rst gave 101 students an example generation task during a lecture. In this task, students were asked to generate examples of sequences that satis ed certain combinations of properties. In the second pilot study a similar task was given to six students in an interview setting with a `think-aloud' protocol. These pilot studies found that many students gave sequences that did not satisfy the requested properties, whilst other students gave examples that were not sequences. The thesis then reports on a main study in which the example generation task was completed by 15 students during an interview, and 147 students during classes. The interview data is analysed phenomenographically, with results presented along four dimensions of variation, where each dimension describes di erent ways of experiencing an aspect of sequence example generation: Using De nitions, Representation of Sequences, Sequence Construction Strategies, and Justi cations. The larger-scale class data is then analysed by Rasch Analysis to objectively rank the questions in order of their di culty, and to show that the interview-based responses re ect those in the wider cohort. By asking students to generate their own examples of sequences, this thesis has furthered what is known about student understanding in two areas. The rst area is how students understand content related to sequences in Analysis. The thesis considers students' understanding of how sequences can be represented, how sequence property de nitions can be combined and how de nitions a ect sequences in di erent ways. The second area is how students interact with example generation tasks, the approaches that are e ective when students are trying to generate examples, and the ways students justify or check their answers

Using Rasch analysis to identify uncharacteristic responses to undergraduate assessments

Rasch Analysis is a statistical technique that is commonly used to analyse both test data and Likert survey data, to construct and evaluate question item banks, and to evaluate change in longitudinal studies. In this article, we introduce the dichotomous Rasch model, briefly discussing its assumptions. Then, using data collected in an example-generation task with undergraduate mathematics students, we use Rasch analysis to (1) rank the task questions and consider this ranking in relation to students’ conceptions and (2) identify those students whose responses misfit the model (e.g. students who score highly but get easier questions wrong). We conclude that because these responses misfit the Rasch model they are worthy of further (qualitative) examination, for instance to aid the discovery and classification of students’ misconceptions relative to formal theory

Components + Security = OS Extensibility

Component-based programming systems have shown themselves to be a natural way of constructing extensible software. Well-defined interfaces, encapsulation, late binding and polymorphism promote extensibility, yet despite this synergy, components have not been widely employed at the systems level. This is primarily due to the failure of existing component technologies to provide the protection and performance required of systems software. In this paper we identify the requirements for a component system to support secure extensions, and describe the design of such a system on the Mungi OS

Implementation of patient charges at primary care facilities in Kenya: implications of low adherence to user fee policy for users and facility revenue.

With user fees now seen as a major hindrance to universal health coverage, many countries have introduced fee reduction or elimination policies, but there is growing evidence that adherence to reduced fees is often highly imperfect. In 2004, Kenya adopted a reduced and uniform user fee policy providing fee exemptions to many groups. We present data on user fee implementation, revenue and expenditure from a nationally representative survey of Kenyan primary health facilities. Data were collected from 248 randomly selected public health centres and dispensaries in 2010, comprising an interview with the health worker in charge, exit interviews with curative outpatients, and a financial record review. Adherence to user fee policy was assessed for eight tracer conditions based on health worker reports, and patients were asked about actual amounts paid. No facilities adhered fully to the user fee policy across all eight tracers, with adherence ranging from 62.2% for an adult with tuberculosis to 4.2% for an adult with malaria. Three quarters of exit interviewees had paid some fees, with a median payment of US dollars (USD) 0.39, and a quarter of interviewees were required to purchase additional medical supplies at a later stage from a private drug retailer. No consistent pattern of association was identified between facility characteristics and policy adherence. User fee revenues accounted for almost all facility cash income, with average revenue of USD 683 per facility per year. Fee revenue was mainly used to cover support staff, non-drug supplies and travel allowances. Adherence to user fee policy was very low, leading to concerns about the impact on access and the financial burden on households. However, the potential to ensure adherence was constrained by the facilities' need for revenue to cover basic operating costs, highlighting the need for alternative funding strategies for peripheral health facilities

Clitellate worms (Annelida) in late-glacial and Holocene sedimentary DNA records from the Polar Urals and northern Norway

While there are extensive macro‐ and microfossil records of a range of plants and animals from the Quaternary, earthworms and their close relatives amongst annelids are not preserved as fossils and therefore the knowledge of their past distributions is limited. This lack of fossils means that clitellate worms (Annelida) are currently underused in palaeoecological research, even though they can provide valuable information about terrestrial and aquatic environmental conditions. Their DNA might be preserved in sediments, which offers an alternative method for detection. Here we analyse lacustrine sediments from lakes in the Polar Urals, Arctic Russia, covering the period 24 000–1300 cal. a BP, and NE Norway, covering 10 700–3300 cal. a BP, using a universal mammal 16S rDNA marker. While mammals were recorded using the marker (reindeer was detected twice in the Polar Urals core at 23 000 and 14 000 cal. a BP, and four times in the Norwegian core at 11 000 cal. a BP and between 3600–3300 cal. a BP), worm extracellular DNA ‘bycatch’ was rather high. In this paper we present the first reported worm detection from ancient DNA. Our results demonstrate that both aquatic and terrestrial clitellates can be identified in late‐Quaternary lacustrine sediments, and the ecological information retrievable from this group warrants further research with a more targeted approach.publishedVersio

Holocene floristic diversity and richness in northeast Norway revealed by sedimentary ancient DNA (sedaDNA) and pollen

Source at https://doi.org/10.1111/bor.12357We present a Holocene record of floristic diversity and environmental change for the central Varanger Peninsula, Finnmark, based on ancient DNA extracted from the sediments of a small lake (sedaDNA). The record covers the period c. 10 700 to 3300 cal. a BP and is complemented by pollen data. Measures of species richness, sample evenness and beta diversity were calculated based on sedaDNA sampling intervals and 1000‐year time windows. We identified 101 vascular plant and 17 bryophyte taxa, a high proportion (86%) of which are still growing within the region today. The high species richness (>60 taxa) observed in the Early Holocene, including representatives from all important plant functional groups, shows that modern shrub‐tundra communities, and much of their species complement, were in place as early as c. 10 700 cal. a BP. We infer that postglacial colonization of the area occurred prior to the full Holocene, during the Pleistocene‐Holocene transition, Younger Dryas stadial or earlier. Abundant DNA of the extra‐limital aquatic plant Callitriche hermaphroditica suggests it expanded its range northward between c. 10 200 and 9600 cal. a BP, when summers were warmer than present. High values of Pinus DNA occur throughout the record, but we cannot say with certainty if they represent prior local presence; however, pollen influx values >500 grains cm−2 a−1 between c. 8000 and 7300 cal. a BP strongly suggest the presence of pine woodland during this period. As the site lies beyond the modern tree limit of pine, it is likely that this expansion also reflects a response to warmer Early Holocene summers

Which doctors and with what problems contact a specialist service for doctors? A cross sectional investigation

Background: In the United Kingdom, specialist treatment and intervention services for doctors are underdeveloped. The MedNet programme, created in 1997 and funded by the London Deanery, aims to fill this gap by providing a self-referral, face-to-face, psychotherapeutic assessment service for doctors in London and South-East England. MedNet was designed to be a low-threshold service, targeting doctors without formal psychiatric problems. The aim of this study was to delineate the characteristics of doctors utilising the service, to describe their psychological morbidity, and to determine if early intervention is achieved. Methods: A cross-sectional study including all consecutive self-referred doctors (n = 121, 50% male) presenting in 2002–2004 was conducted. Measures included standardised and bespoke questionnaires both self-report and clinician completed. The multi-dimensional evaluation included: demographics, CORE (CORE-OM, CORE-Workplace and CORE-A) an instrument designed to evaluate the psychological difficulties of patients referred to outpatient services, Brief Symptom Inventory to quantify caseness and formal psychiatric illness, and Maslach Burnout Inventory. Results: The most prevalent presenting problems included depression, anxiety, interpersonal, self-esteem and work-related issues. However, only 9% of the cohort were identified as severely distressed psychiatrically using this measure. In approximately 50% of the sample, problems first presented in the preceding year. About 25% were on sick leave at the time of consultation, while 50% took little or no leave in the prior 12 months. A total of 42% were considered to be at some risk of suicide, with more than 25% considered to have a moderate to severe risk. There were no significant gender differences in type of morbidity, severity or days off sick. Conclusion: Doctors displayed high levels of distress as reflected in the significant proportion of those who were at some risk of suicide; however, low rates of severe psychiatric illness were detected. These findings suggest that MedNet clients represent both ends of the spectrum of severity, enabling early clinical engagement for a significant proportion of cases that is of importance both in terms of personal health and protecting patient care, and providing a timely intervention for those who are at risk, a group for whom rapid intervention services are in need and an area that requires further investigation in the UK