5,403 research outputs found

    A Delphi study on collaborative learning in distance education

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    Collaborative Learning (CL) is increasingly being used in Distance Education (DE), as it has been identified as an effective solution to known weaknesses such as high average rates of dropout and low quality of learning attainment. Information Technology is a core component of this type of learning as it not only provides the means to collaborate over distance but also has the potential to enable higher learning outcomes. There are a rapidly growing number of technologies in use today and the importance of these to collaborative learning initiatives, and the role they play, is an area of active research in the Information Systems (IS) community. IS educators and practitioners face an increasing challenge therefore to successfully implement CL in DE, precipitated not only from technical advances but also from wider social and organisational concerns. Using a Delphi study, this research is the first to investigate the factors that influence collaborative learning in distance education by surveying the opinions of an expert panel in this area. The aim was to produce an integrated list of the most important implementation factors and to investigate the role technology is perceived to contribute. The findings identified seventeen of the most important factors. These factors cover a range of themes including course rationale and design, instructor characteristics, training, group dynamics, the development of a learning community and technology. The potential of technology however does not seem to be fully realised and newer technologies such as multi-user environments would seem to be of limited use in practice, according to the expert panel

    Object-Centered Shifts of Receptive Field Positions in Monkey Primary Visual Cortex

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    SummaryStimuli that project the same retinal visual angle can appear to occupy very different proportions of the visual field if they are perceived to be at different distances [1–8]. Previous research shows that perceived angular size alters the spatial distribution of activity in early retinotopic visual cortex [7, 9–11]. For example, a sphere superimposed on the far end of a corridor scene appears to occupy a larger visual angle and activates a larger region of primary visual cortex (V1) compared with the same sphere superimposed on the near end of the corridor [7]. These previous results, however, were obtained from human subjects using psychophysics and fMRI, a fact that fundamentally limits our understanding of the underlying neuronal mechanisms. Here, we present an animal model that allows for a finer examination of size perception at the level of single neurons. We first show that macaque monkeys perceive a size-distance illusion similarly to humans. Then, using extracellular recordings, we test the specific hypothesis [12] that neurons in V1 shift the position of their receptive fields (RFs) in response to complex monocular depth cues. Consistent with this hypothesis, we found that when ring-shaped stimuli appeared at the back of the corridor, RFs of V1 neurons shifted toward the center of the rings. When the same stimuli appeared at the front of the corridor, RFs shifted outward. Thus, our results show for the first time that V1 RFs can shift, potentially serving as the neural basis for the perception of angular size

    Discovery of X-ray Pulsations from the Compact Central Source in the Supernova Remnant 3C 58

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    We report on high time resolution observations of the SNR 3C 58 using the High Resolution Camera on the Chandra X-ray Observatory. These data show a point-like central source, from which we detect 65.68 ms pulsations at 6.7 sigma significance. We interpret these pulsations as corresponding to a young rotation-powered pulsar (PSR J-205+6449) which is associated with, and powers, 3C 58. Analysis of archival RXTE data from three years earlier confirms these pulsations, and allows us to determine a spin-down rate of P-dot=1.93x10^-13 s/s. Assuming a magnetic dipole model for PSR J0205+6449, we infer a surface magnetic field of 3.6x10^12 G. The characteristic age for this pulsar is 5400 yr, indicating either that 3C 58 was not the supernova of 1181 CE, or that the pulsar's initial spin period was ~60 ms.Comment: 11 pages, 4 figures, 1 tabl

    Using consecutive Rapid Participatory Appraisal studies to assess, facilitate and evaluate health and social change in community settings

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    BACKGROUND: To investigate how a relatively socio-economically deprived community's needs have changed over time, assess which recommendations from an earlier assessment were implemented and sustained, and consider whether serial Rapid Participatory Appraisal is an effective health research tool that can promote community development and has utility in assessing longitudinal change. METHODS: Rapid Participatory Appraisal involves communities in identifying and challenging their own health-related needs. Information on ten health and social aspects was collated from existing documentation, neighbourhood observations, and interviews with a range of residents and key informants, providing a composite picture of the community's structure, needs and services. RESULTS: The perceived needs after 10 years encompassed a wide construct of health, principally the living environment, housing, and lack of finance. Most identified upstream determinants of health rather than specific medical conditions as primary concerns. After the initial Rapid Participatory Appraisal many interviewees took the recommendations forward, working to promote a healthier environment and advocate for local resources. Interventions requiring support from outwith the community were largely not sustained. CONCLUSION: Rapid Participatory Appraisal proved valuable in assessing long-term change. The community's continuing needs were identified, but they could not facilitate and sustain change without the strategic support of key regional and national agencies. Many repeatedly voiced concerns lay outwith local control: local needs assessment must be supported at higher levels to be effective

    Immune Response to the West Nile Virus in Aged Non-Human Primates

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    Background: Risk of encephalitis from West Nile virus (WNV) infection increases dramatically with age. Understanding the basis of this susceptibility requires development of suitable animal models. Here, we investigated the immune response to WNV in old non-human primates. Methodology/Principal Findings: We investigated clinical, immunological and virological correlates of WNV infection in aging non-human primates. Aged (17-30yrs) and adult (6-9yrs) Rhesus macaques (RM) were challenged with WNV in the presence or the absence of the mosquito salivary gland extract (SGE) to approximate natural infection. None of the 26 animals exhibited clinical signs of the disease. Quantitative PCR suggested discrete and short-lived viremia, but infectious virus was never isolated. There was markedly increased, age-independent, proliferation of CD3- non-B cells, followed by Bcell proliferation, which correlated to the loss of detectable WNV genomes. Moreover, animals primed with mosquito salivary gland extract exhibited reduced circulating WNV RNA. While we found the expected age-associated reduction in T cell proliferation, adaptive immunity did not correlate with infection outcome. That was further confirmed in a cohort of thymectomized and/or CD8 T-cell depleted Cynomolgus macaques (CM; N = 15), who also failed to develop WNV disease. Conclusions/significance: Results are consistent with strong and age-independent innate resistance of macaques against WNV challenge. This animal model is therefore not suitable for vaccine and therapeutic testing against WNV. However, understanding the basis of their innate resistance against WNV in macaques could provide helpful clues to improve anti- WNV protection of older adults. © 2010 Wertheimer et al

    Evidence for the role of EPHX2 gene variants in anorexia nervosa.

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    Anorexia nervosa (AN) and related eating disorders are complex, multifactorial neuropsychiatric conditions with likely rare and common genetic and environmental determinants. To identify genetic variants associated with AN, we pursued a series of sequencing and genotyping studies focusing on the coding regions and upstream sequence of 152 candidate genes in a total of 1205 AN cases and 1948 controls. We identified individual variant associations in the Estrogen Receptor-ß (ESR2) gene, as well as a set of rare and common variants in the Epoxide Hydrolase 2 (EPHX2) gene, in an initial sequencing study of 261 early-onset severe AN cases and 73 controls (P=0.0004). The association of EPHX2 variants was further delineated in: (1) a pooling-based replication study involving an additional 500 AN patients and 500 controls (replication set P=0.00000016); (2) single-locus studies in a cohort of 386 previously genotyped broadly defined AN cases and 295 female population controls from the Bogalusa Heart Study (BHS) and a cohort of 58 individuals with self-reported eating disturbances and 851 controls (combined smallest single locus P<0.01). As EPHX2 is known to influence cholesterol metabolism, and AN is often associated with elevated cholesterol levels, we also investigated the association of EPHX2 variants and longitudinal body mass index (BMI) and cholesterol in BHS female and male subjects (N=229) and found evidence for a modifying effect of a subset of variants on the relationship between cholesterol and BMI (P<0.01). These findings suggest a novel association of gene variants within EPHX2 to susceptibility to AN and provide a foundation for future study of this important yet poorly understood condition

    Wordwide patterns of genetic differentiation imply multiple ‘domestications’of Aedes aegypti, a major vector of human diseases

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    Understanding the processes by which species colonize and adapt to human habitats is particularly important in the case of disease-vectoring arthropods. The mosquito species Aedes aegypti, a major vector of dengue and yellow fever viruses, probably originated as a wild, zoophilic species in sub-Saharan Africa, where some populations still breed in tree holes in forested habitats. Many populations of the species, however, have evolved to thrive in human habitats and to bite humans. This includes some populations within Africa as well as almost all those outside Africa. It is not clear whether all domestic populations are genetically related and represent a single ‘domestication’ event, or whether association with human habitats has developed multiple times independently within the species. To test the hypotheses above, we screened 24 worldwide population samples of Ae. aegypti at 12 polymorphic microsatellite loci. We identified two distinct genetic clusters: one included all domestic populations outside of Africa and the other included both domestic and forest populations within Africa. This suggests that human association in Africa occurred independently from that in domestic populations across the rest of the world. Additionally, measures of genetic diversity support Ae. aegypti in Africa as the ancestral form of the species. Individuals from domestic populations outside Africa can reliably be assigned back to their population of origin, which will help determine the origins of new introductions of Ae. aegypti

    Community Resilience to Climate Change : Summary for policy and practice

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    The Scottish Borders Climate Resilient Communities Project (SBCRC)1 was a participatory action research project that sought to build community resilience to climate change through working in three communities with a history of flooding in the Scottish Borders. It aimed to:- Understand some of the critical factors that contribute to shaping community resilience in the context of climate disadvantage;- Understand how community resilience to climate change can be developed in different local contexts in practice by supporting and facilitating engagement between members of three local communities and other stakeholders in the Scottish Borders region, and evaluating outcomes;- Draw out lessons for policymakers and practitioners on how to support the development of community resilience in the context of climate change.The project was structured around nine workshops (three per community) that brought together different organisations (e.g. the Scottish Borders Council, local NGOs) to examine issues and develop actions to build community resilience in the context of climate change. A tenth workshop used the outcomes from the work within the communities to examine how a more integrated and synergistic national policy landscape in Scotland could be developed to enhance community resilience to climate change. An evaluation helped to inform project delivery and the overall findings
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