The effect(s) of dose and dose-rate of ionising radiation on early lens epithelial cell response and cataractogenesis

The lens of the eye is thought to be one of the most radiosensitive tissues. Cataracts were one of the first observed biological effects following ionising radiation exposure. The recent change in regulations for eye lens dose limits has led to the urgent need to make sure our biological understanding is sufficient. The anterior of the lens is covered by lens epithelial cells (LEC), that are critical to maintaining normal lens function and producing fibre cells. Damage or disruption to LECs can have detrimental consequences to the lens. Low dose (<500 mGy) radiation-induced DNA damage and repair, cell proliferation and lens opacity were investigated post-exposure in or amongst four mouse strains (C57BL/6,129S2, BALB/c and CBA/Ca). Mice were sacrificed up to 24 hours post-exposure and lenses removed and epithelia isolated for analyses. Immunofluorescent staining for DNA double strand break (DSB) repair (53BP1) and cell proliferation (Ki67) were performed. Dose, dose-rates were varied during exposures to seek experimental evidence to support the epidemiological studies. Peripheral blood lymphocytes were collected for comparison with LEC. 120 female mice were irradiated and their lenses analysed for opacity at monthly intervals over 18 months. An inverse dose-rate effect was observed in the DSB repair response, as well as slower repair at low IR doses and a significant strain dependency. A nonlinear response to IR was observed for LEC proliferation that was bimodal; inhibition at low dose (<50 mGy), and a significant interaction effect between dose-rate and region. Lens opacity also increased over time. These results give the first biological evidence for an inverse dose-rate response in the lens. They highlight the importance of dose-rate in low-dose cataract formation represent the first evidence that LECs process radiation damage differently to blood lymphocytes. More work is needed to support lens dose limits

Integration of New Biological and Physical Retrospective Dosimetry Methods Into EU Emergency Response Plans – Joint RENEB and EURADOS Inter-Laboratory Comparisons

RENEB, \u27Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,\u27 is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation

The second gamma-H2AX assay inter-comparison exercise carried out in the framework of the European biodosimetry network (RENEB)

Purpose: Within the EU RENEB project, seven laboratories have taken part in training and harmonisation activities to strengthen triage gamma H2AX-based radiation exposure assessment. This has culminated in a second triage biodosimetry exercise. Materials and methods: Whole blood and separated lymphocyte samples were homogenously irradiated with 60Co gamma rays at 0.5, 2.5 (blind samples), 0 and 2 Gy (reference samples). Following post-exposure incubations of 4 and 24 h, 16 samples were shipped on ice packs to each partner. The samples were stained and scored for gamma-H2AX foci, using manual and/or automated fluorescence microscope scoring strategies. Dose estimates were obtained and used to assign triage categories to the samples. Results: Average dose estimates across all the laboratories correlated well with true doses. The most accurate assignment of triage category was achieved by manual scoring of the 4-h blood and lymphocyte samples. Only three samples out of a total of 46 were miscategorized in a way that could have adversely effected the clinical management of a radiation casualty. Conclusions: This inter-comparison exercise has demonstrated that following a recent acute radiation exposure, the gamma-H2AX assay could be a useful triage tool that can be successfully applied across a network of laboratories

Crooked coverage: a study of (de)racialized texts in print media

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on January 3, 2008)Vita.Includes bibliographical references.Thesis (M.A.) University of Missouri-Columbia 2007.Dissertations, Academic -- University of Missouri--Columbia -- Sociology.On top of the intense history of racism in America, recent research has shown the increasing importance of color-blind racism and its impact on our society. While many studies have shown that racism exists in the media, few have been able to explain how media providers institutionalize racism. Thus, while media outlets have been proven to display racist sentiments, few studies have shown how racism is operationalized (and executed) within a given media institution. The goal of this study is to explore the possibility of such practices. By taking a purposive sample of news articles from both the Columbia Daily Tribune and the New York Times, I conduct a content analysis to explore how these two newspapers treat race issues. Do journalistic models (such as the inverted pyramid style of reporting) function as injectors of racial bias? Additionally, what role do indirect racial codes have in coverage of race issues? Answers to these questions will yield important results in explaining whether or not media outlets institutionalize racism (and if so, how). Given the vast amount of research showing the immense effect media can have on public opinion, the understanding of how the media perpetuates racism is imperative to develop a comprehensive understanding of contemporary racism

Targets for the MalI repressor at the divergent Escherichia coliK-12malX-malI promoters

Random mutagenesis has been used to identify the target DNA sites for the MalI repressor at the divergent Escherichia coli K-12 malX-malI promoters. The malX promoter is repressed by MalI binding to a DNA site located from position -24 to position -9, upstream of the malX promoter transcript start. The malI promoter is repressed by MalI binding from position +3 to position +18, downstream of the malI transcript start. MalI binding at the malI promoter target is not required for repression of the malX promoter. Similarly, MalI binding at the malX promoter target is not required for repression of the malI. Although the malX and malI promoters are regulated by a single DNA site for cyclic AMP receptor protein, they function independently and each is repressed by MalI binding to a different independent operator site

A new globular cluster black hole in NGC 4472

We discuss CXOU~1229410+075744, a new black hole candidate in a globular cluster in the elliptical galaxy NGC~4472. By comparing two Chandra observations of the galaxy, we find a source that varies by at least a factor of 4, and has a peak luminosity of at least $2\times10^{39}$ ergs/sec. As such, the source varies by significantly more than the Eddington luminosity for a single neutron star, and is a strong candidate for being a globular cluster black hole. The source's X-ray spectrum also evolves in a manner consistent with what would be expected from a single accreting stellar mass black hole. We consider the properties of the host cluster of this source and the six other strong black hole X-ray binary candidates, and find that there is suggestive evidence that black hole X-ray binary formation is favored in bright and metal rich clusters, just as is the case for bright X-ray sources in general.Comment: 6 pages, one 2-panel figure, 2 tables; accepted to MNRA

Long-Range Exciton Diffusion in Two-Dimensional Assemblies of Cesium Lead Bromide Perovskite Nanocrystals

F\"orster Resonant Energy Transfer (FRET)-mediated exciton diffusion through artificial nanoscale building block assemblies could be used as a new optoelectronic design element to transport energy. However, so far nanocrystal (NC) systems supported only diffusion length of 30 nm, which are too small to be useful in devices. Here, we demonstrate a FRET-mediated exciton diffusion length of 200 nm with 0.5 cm2/s diffusivity through an ordered, two-dimensional assembly of cesium lead bromide perovskite nanocrystals (PNC). Exciton diffusion was directly measured via steady-state and time-resolved photoluminescence (PL) microscopy, with physical modeling providing deeper insight into the transport process. This exceptionally efficient exciton transport is facilitated by PNCs high PL quantum yield, large absorption cross-section, and high polarizability, together with minimal energetic and geometric disorder of the assembly. This FRET-mediated exciton diffusion length matches perovskites optical absorption depth, opening the possibility to design new optoelectronic device architectures with improved performances, and providing insight into the high conversion efficiencies of PNC-based optoelectronic devices

The challenges of optimising glycaemic control in children with type 1 diabetes: a qualitative study of parents’ experiences and views

Aims To explore the difficulties parents encounter in trying to achieve clinically recommended blood glucose levels and how they could be better supported to optimize their child's glycaemic control. Methods In-depth interviews were conducted with 54 parents of children with Type 1 diabetes (≤ 12 years). Data were analysed thematically. Results Parents described being reluctant and finding it difficult to keep their child's blood glucose levels consistently within clinically recommended ranges. As well as worrying about their child's ability to detect/report hypoglycaemia, parents highlighted a multitude of factors that had an impact on their child's blood glucose levels and over which they could exercise little control. These included: leaving their child with other caregivers who could not be trusted to detect hypoglycaemia; difficulties remotely monitoring and regulating their child's food consumption and activity; and physical and social changes accompanying childhood development. Most parents used two sets of blood glucose targets, with clinically recommended targets employed when their child was in their immediate care and higher targets when in the care of others. Parents described health professionals as lacking understanding of the difficulties they encountered keeping blood glucose within target ranges and needing more empathetic, tailored and realistic advice. Conclusion It is not parents' fear of hypoglycaemia in isolation that leads to decisions to raise their child's blood glucose but, rather, parental fear in conjunction with other factors and considerations. Hence, to improve diabetes management in children, these factors may need to be addressed; for instance, by training others in diabetes management and using new technologies. Changes to consultations are also recommended