10,758 research outputs found

    The Trypanosoma brucei AIR9-like protein is cytoskeleton-associated and is required for nucleus positioning and accurate cleavage furrow placement

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    AIR9 is a cytoskeleton-associated protein in Arabidopsis thaliana with roles in cytokinesis and cross wall maturation, and reported homologues in land plants and excavate protists, including trypanosomatids. We show that the Trypanosoma brucei AIR9-like protein, TbAIR9, is also cytoskeleton-associated and colocalises with the subpellicular microtubules. We find it to be expressed in all life cycle stages and show that it is essential for normal proliferation of trypanosomes in vitro. Depletion of TbAIR9 from procyclic trypanosomes resulted in increased cell length due to increased microtubule extension at the cell posterior. Additionally, the nucleus was re-positioned to a location posterior to the kinetoplast, leading to defects in cytokinesis and the generation of aberrant progeny. In contrast, in bloodstream trypanosomes, depletion of TbAIR9 had little effect on nucleus positioning, but resulted in aberrant cleavage furrow placement and the generation of non-equivalent daughter cells following cytokinesis. Our data provide insight into the control of nucleus positioning in this important pathogen and emphasise differences in the cytoskeleton and cell cycle control between two life cycle stages of the T. brucei parasite

    A broken solar type II radio burst induced by a coronal shock propagating across the streamer boundary

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    We discuss an intriguing type II radio burst that occurred on 2011 March 27. The dynamic spectrum was featured by a sudden break at about 43 MHz on the well-observed harmonic branch. Before the break, the spectrum drifted gradually with a mean rate of about -0.05 MHz/s. Following the break, the spectrum jumped to lower frequencies. The post-break emission lasted for about three minutes. It consisted of an overall slow drift which appeared to have a few fast drift sub-bands. Simultaneous observations from the Solar TErrestrial RElations Observatory (STEREO) and the Solar Dynamics Observatory (SDO) were also available and are examined for this event. We suggest that the slow-drift period before the break was generated inside a streamer by a coronal eruption driven shock, and the spectral break as well as the relatively wide spectrum after the break is a consequence of the shock crossing the streamer boundary where density drops abruptly. It is suggested that this type of radio bursts can be taken as a unique diagnostic tool for inferring the coronal density structure, as well as the radio emitting source region.Comment: 12 pages, 5 figures, accepted by ApJ 201

    The INCENTIVE Study: a mixed methods evaluation of an innovation in commissioning and delivery of primary dental care compared to traditional dental contracting

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    Background Over the past decade, commissioning of primary care dentistry has seen contract currency evolving from payment for units of dental activity (UDAs) towards blended contracts that include key performance indicators such as access, quality and improved health outcome. Objectives The aim of this study was to evaluate a blended/incentive-driven model of dental service provision. To (1) explore stakeholder perspectives of the new service delivery model; (2) assess the effectiveness of the new service delivery model in reducing the risk of and amount of dental disease and enhancing oral health-related quality of life (OHQoL) in patients; and (3) assess cost-effectiveness of the new service delivery model. Methods Using a mixed-methods approach, the study included three dental practices working under the blended/incentive-driven (incentive) contract and three working under the UDAs (traditional) contract. All were based in West Yorkshire. The qualitative study reports on the meaning of key aspects of the model for three stakeholder groups [lay people (patients and individuals without a dentist), commissioners and the primary care dental teams], with framework analysis of focus group and semistructured interview data. A non-randomised study compared clinical effectiveness and cost-effectiveness of treatment under the two contracts. The primary outcome was gingivitis, measured using bleeding on probing. Secondary outcomes included OHQoL and cost-effectiveness. Results Participants in the qualitative study associated the incentive contract with more access, greater use of skill mix and improved health outcomes. In the quantitative analyses, of 550 participants recruited, 291 attended baseline and follow-up. Given missing data and following quality assurance, 188 were included in the bleeding on probing analysis, 187 in the caries assessment and 210 in the economic analysis. The results were mixed. The primary outcome favoured the incentive practices, whereas the assessment of caries favoured the traditional practices. Incentive practices attracted a higher cost for the service commissioner, but were financially attractive for the dental provider at the practice level. Differences in generic health-related quality of life were negligible. Positive changes over time in OHQoL in both groups were statistically significant. Limitations The results of the quantitative analysis should be treated with caution given small sample numbers, reservations about the validity of pooling, differential dropout results and data quality issues. Conclusions A large proportion of people in this study who had access to a dentist did not follow up on oral care. These individuals are more likely to be younger males and have poorer oral health. Although access to dental services was increased, this did not appear to facilitate continued use of services. Future work Further research is required to understand how best to promote and encourage appropriate dental service attendance, especially among those with a high level of need, to avoid increasing health inequalities, and to assess the financial impact of the contract. For dental practitioners, there are challenges around perceptions about preventative dentistry and use of the risk assessments and care pathways. Changes in skill mix pose further challenges. Funding The National Institute for Health Research Health Services and Delivery Research programme

    Miniature exoplanet radial velocity array I: design, commissioning, and early photometric results

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    The MINiature Exoplanet Radial Velocity Array (MINERVA) is a US-based observational facility dedicated to the discovery and characterization of exoplanets around a nearby sample of bright stars. MINERVA employs a robotic array of four 0.7 m telescopes outfitted for both high-resolution spec- troscopy and photometry, and is designed for completely autonomous operation. The primary science program is a dedicated radial velocity survey and the secondary science objective is to obtain high precision transit light curves. The modular design of the facility and the flexibility of our hardware allows for both science programs to be pursued simultaneously, while the robotic control software provides a robust and efficient means to carry out nightly observations. In this article, we describe the design of MINERVA including major hardware components, software, and science goals. The telescopes and photometry cameras are characterized at our test facility on the Caltech campus in Pasadena, CA, and their on-sky performance is validated. New observations from our test facility demonstrate sub-mmag photometric precision of one of our radial velocity survey targets, and we present new transit observations and fits of WASP-52b—a known hot-Jupiter with an inflated radius and misaligned orbit. The process of relocating the MINERVA hardware to its final destination at the Fred Lawrence Whipple Observatory in southern Arizona has begun, and science operations are expected to commence within 2015

    'Country life'? Rurality, folk music and 'Show of Hands'

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    This paper examines the contribution of folk music to understanding the dynamic, fluid and multi-experiential nature of the countryside. Drawing from literature on the geographies of music, it examines the work of 'Show of Hands', a contemporary folk band from Devon in England. Three areas are studied. First, the paper examines the musical style of Show of Hands in order to explore how hybridised, yet distinctive, styles of music emerge in particular places. Second, it demonstrates how Show of Hands' hybrid musical style has become closely associated with the Southwest of England. Finally, within these spatial and hybrid contexts, attention is given to the ways in which their music represents the 'everyday lives of the rural'. Taken together these themes assess the relevance of music in the understanding of rurality as hybrid space. © 2008 Elsevier Ltd. All rights reserved

    Direct Evidence for Termination of Obscured Star Formation by Radiatively Driven Outflows in Reddened QSOs

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    We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from AGN in their rest-frame UV spectra. We use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10^{12} Solar luminosities in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGN can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.Comment: Accepted for publication in Ap

    Coupling slot-waveguide cavities for large-scale quantum optical devices

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    By offering effective modal volumes significantly less than a cubic wavelength, slot-waveguide cavities offer a new in-road into strong atom-photon coupling in the visible regime. Here we explore two-dimensional arrays of coupled slot cavities which underpin designs for novel quantum emulators and polaritonic quantum phase transition devices. Specifically, we investigate the lateral coupling characteristics of diamond-air and GaP-air slot waveguides using numerically-assisted coupled-mode theory, and the longitudinal coupling properties via distributed Bragg reflectors using mode-propagation simulations. We find that slot-waveguide cavities in the Fabry-Perot arrangement can be coupled and effectively treated with a tight-binding description, and are a suitable platform for realizing Jaynes-Cummings-Hubbard physics.Comment: 11 pages, 7 figures, submitte

    Trends in education in Northern England during the eighteenth century :a biographical study

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    PhD ThesisThe education of the intellectual elite of the eighteenth century. The eighteenth century has been neglected in studies of the history of English education. The great pioneers of this field, Leach and Foster-Watson concentrated their efforts upon the sixteenth and seventeenth centuries. Their work, supplemented by the monumental researches of Jordan, provided the factual basis for later interpretations of the educational trends in England before 1660. However little of their writings concerned the eighteenth century and no other scholar of the same stature repaired this omission. There were indeed specialist studies of certain facets of education between 1660 and 1800. The dissenting academies were described in some detail, by Parker and McLachlan, the charity schools found their historiographer in Miss Jones, and eighteenth century. Cambridge was lovingly delineated by Winstanley. The rise of the public schools was examined by E. C. Mack. The education available for women was discussed by Miss Gardiner. A few unpublished theses also dealt with eighteenth century aspects of education. Little however was written until very recently about endowed or private schools, although these were numerically far more important
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