7,220 research outputs found

    Light structures phototroph, bacterial and fungal communities at the soil surface

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    The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0–3 mm) and bulk soil (3–12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere

    The main sequence of three red supergiant clusters

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    Massive clusters in our Galaxy are an ideal testbed to investigate the properties and evolution of high-mass stars. They provide statistically significant samples of massive stars of uniform ages. To accurately determine the intrinsic physical properties of these stars, we need to establish the distances, ages and reddening of the clusters. One avenue to achieve this is the identification and characterization of the main-sequence (MS) members of red supergiant (RSG) rich clusters. Here, we utilize publicly available data from the UKIDSS Galactic Plane Survey. We show that point spread function photometry in conjunction with standard photometric decontamination techniques allows us to identify the most likely MSmembers in the 10-20 Myr old clusters RSGC 1-3. We confirm the previous detection of the MS in RSGC 2 and provide the first MS detection in RSGC 1 and RSGC 3. There are in excess of 100 stars with more than 8Mâ?? identified in each cluster. These MS members are concentrated towards the spectroscopically confirmed RSG stars. We utilize the J-K colours of the bright MS stars to determine the K-band extinction towards the clusters. The differential reddening is three times as large in the youngest cluster RSGC 1 as compared to the two older clusters RSGC 2 and RSGC 3. Spectroscopic follow-up of the cluster MS stars should lead to more precise distance and age estimates for these clusters as well as the determination of the stellar mass function in these high-mass environments. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

    Using video feedback to improve early father-infant interaction: a pilot study.

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    Preventive interventions with parents of infants have tended to focus on mothers. Recent research focused on fathers suggests that their involvement in interventions might enhance effectiveness. One effective approach with mothers is the brief, home-based Video-feedback Intervention to promote Positive Parenting (VIPP). This paper is a report of a pilot study of VIPP with fathers to assess its feasibility. Five fathers were recruited from an existing longitudinal study of parents. The primary outcome was acceptability, assessed using a semi-structured questionnaire after completion of the intervention. All fathers completed all sessions of the intervention. Fathers rated the intervention as having had a significant impact on their understanding of their child's thoughts and feelings, and as having improved their communication and relationship with their baby. Fathers' feedback was generally positive. The flexibility to conduct sessions at home (or at fathers' places of work) and the flexible timing of sessions were identified as fundamental to successful delivery. The results of this pilot study are encouraging, as VIPP with fathers was feasible. In light of the modest sample size, and the use of a non-clinical sample, the intervention must be evaluated with larger, clinical samples to evaluate its efficacy with fathers

    Reframing e-assessment: building professional nursing and academic attributes in a first year nursing course

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    This paper documents the relationships between pedagogy and e-assessment in two nursing courses offered at the University of Southern Queensland, Australia. The courses are designed to build the academic, numeracy and technological attributes student nurses need if they are to succeed at university and in the nursing profession. The paper first outlines the management systems supporting the two courses and how they intersect with the e-learning and e-assessment components of course design. These pedagogical choices are then reviewed. While there are lessons to be learnt and improvements to be made, preliminary results suggest students and staff are extremely supportive of the courses. The e-assessment is very positively received with students reporting increased confidence and competency in numeracy, as well as IT, academic, research and communication skills

    Cellular Pathways Leading to Patterns of Lytic Epstein-Barr Virus Reactivation in Immortalized B Cell Lines

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    Lymphoblastoid cell lines (LCLs) are created by culturing lymphocytes from the peripheral blood and adding Epstein-Barr virus (EBV), a ubiquitous human herpesvirus which infects, activates, and transforms B cells. These cell lines are used for genotyping, as targets for cytotoxic cells, and as models for EBV immortalization of B cells, particularly post-transplant lymphoproliferative disease (PTLD) in which EBV-immortalized cells proliferate in the absence of a cytotoxic T-cell response. Studies have shown more diversity in LCLs than would be expected from cell lines that are often treated as interchangeable. It is not known how their diversity in factors like morphology, growth factor production, or cellular gene expression influences the EBV life cycle. In this study I investigated connections between LCLs' cellular and viral phenotypes, categorizing them as either low in EBV copy number or fluctuating within a high range. As measured by lytic EBV replication and viral gene expression, LCLs showed high or low lytic permissivity, with permissivity defined as the likelihood that a cell will switch from stable latent infection into the lytic EBV life cycle. Permissivity was not affected by blocking the late events of the lytic cycle. I used flow cytometry to characterize 19 aspects of LCL surface phenotype, but found little association with lytic permissivity. Microarrays and PCR were used to identify genes expressed at higher levels in non-permissive LCLs, including transcription factors that maintain B cell lineage. Unfolded protein response (UPR) genes and the UPR protein Grp94 were expressed at higher levels in permissive LCLs. A drug was used to investigate effects of the UPR on permissive and non-permissive LCLs that had been maintained for short or long periods of time. The UPR enhanced permissivity, causing more cells to enter the lytic cycle, but this did not lead to lytic replication. This study enhances our knowledge about EBV life cycles by giving us new information about host factors that contribute to the lytic switch. This data about LCL diversity has public health relevance to the diversity of PTLD cases, since identifying risk factors for PTLD is a significant part of care for EBV-positive transplant recipients
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