867 research outputs found

    Supporting children's narrative composition : the development and reflection of a visual approach for 7-8 year-olds

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    At the heart of present literacy, and narrative, learning paradigms are the "literate behaviours" usually associated with aspects of learning to encode and decode print. These paradigms have been criticized for placing written and verbal language in a privileged position. Furthermore, whilst an increasing number of theorists and educators are asking for the inclusion of multimodal approaches to learning narrative, current curricula, and the research that informs it, continue to be founded on "verbocentric" approaches and linear forms of narrative expression. Through the development and evaluation of a curricular approach to narrative learning for 7-8 year-olds based on the visual arts, this study aims to ascertain whether there is a need for broader conceptions of narrative as well as for complementary modes of narrative composition than those currently being used in primary schools. Documentation in the form of the children‘s painted narratives and transcripts of the children's oral accounts of their narratives was the major component of data collection. Individual and small group interviews and participant observation were supplementary sources to assist in the interpretation of the narrative paintings the children composed. The children‘s narratives were analysed using a narratological semiotic model, which divides narrative into 'discourse' and 'story' and distinguishes between the 'content' and 'form' of each of these elements.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Composition, structure and stability of RuO_2(110) as a function of oxygen pressure

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    Using density-functional theory (DFT) we calculate the Gibbs free energy to determine the lowest-energy structure of a RuO_2(110) surface in thermodynamic equilibrium with an oxygen-rich environment. The traditionally assumed stoichiometric termination is only found to be favorable at low oxygen chemical potentials, i.e. low pressures and/or high temperatures. At realistic O pressure, the surface is predicted to contain additional terminal O atoms. Although this O excess defines a so-called polar surface, we show that the prevalent ionic model, that dismisses such terminations on electrostatic grounds, is of little validity for RuO_2(110). Together with analogous results obtained previously at the (0001) surface of corundum-structured oxides, these findings on (110) rutile indicate that the stability of non-stoichiometric terminations is a more general phenomenon on transition metal oxide surfaces.Comment: 12 pages including 5 figures. Submitted to Phys. Rev. B. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    Understanding adhesion at as-deposited interfaces from ab initio thermodynamics of deposition growth: thin-film alumina on titanium carbide

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    We investigate the chemical composition and adhesion of chemical vapour deposited thin-film alumina on TiC using and extending a recently proposed nonequilibrium method of ab initio thermodynamics of deposition growth (AIT-DG) [Rohrer J and Hyldgaard P 2010 Phys. Rev. B 82 045415]. A previous study of this system [Rohrer J, Ruberto C and Hyldgaard P 2010 J. Phys.: Condens. Matter 22 015004] found that use of equilibrium thermodynamics leads to predictions of a non-binding TiC/alumina interface, despite the industrial use as a wear-resistant coating. This discrepancy between equilibrium theory and experiment is resolved by the AIT-DG method which predicts interfaces with strong adhesion. The AIT-DG method combines density functional theory calculations, rate-equation modelling of the pressure evolution of the deposition environment and thermochemical data. The AIT-DG method was previously used to predict prevalent terminations of growing or as-deposited surfaces of binary materials. Here we extent the method to predict surface and interface compositions of growing or as-deposited thin films on a substrate and find that inclusion of the nonequilibrium deposition environment has important implications for the nature of buried interfaces.Comment: 8 pages, 6 figures, submitted to J. Phys.: Condens. Matte

    Methyl-CpG-binding domain sequencing reveals a prognostic methylation signature in neuroblastoma

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    Accurate assessment of neuroblastoma outcome prediction remains challenging. Therefore, this study aims at establishing novel prognostic tumor DNA methylation biomarkers. In total, 396 low- and high-risk primary tumors were analyzed, of which 87 were profiled using methyl-CpG-binding domain (MBD) sequencing for differential methylation analysis between prognostic patient groups. Subsequently, methylation-specific PCR (MSP) assays were developed for 78 top-ranking differentially methylated regions and tested on two independent cohorts of 132 and 177 samples, respectively. Further, a new statistical framework was used to identify a robust set of MSP assays of which the methylation score (i.e. the percentage of methylated assays) allows accurate outcome prediction. Survival analyses were performed on the individual target level, as well as on the combined multimarker signature. As a result of the differential DNA methylation assessment by MBD sequencing, 58 of the 78 MSP assays were designed in regions previously unexplored in neuroblastoma, and 36 are located in non-promoter or non-coding regions. In total, 5 individual MSP assays (located in CCDC177, NXPH1, lnc-MRPL3-2, lnc-TREX1-1 and one on a region from chromosome 8 with no further annotation) predict event-free survival and 4 additional assays (located in SPRED3, TNFAIP2, NPM2 and CYYR1) also predict overall survival. Furthermore, a robust 58-marker methylation signature predicting overall and event-free survival was established. In conclusion, this study encompasses the largest DNA methylation biomarker study in neuroblastoma so far. We identified and independently validated several novel prognostic biomarkers, as well as a prognostic 58-marker methylation signature

    First-principles study of the polar O-terminated ZnO surface in thermodynamic equilibrium with oxygen and hydrogen

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    Using density-functional theory in combination with a thermodynamic formalism we calculate the relative stability of various structural models of the polar O-terminated (000-1)-O surface of ZnO. Model surfaces with different concentrations of oxygen vacancies and hydrogen adatoms are considered. Assuming that the surfaces are in thermodynamic equilibrium with an O2 and H2 gas phase we determine a phase diagram of the lowest-energy surface structures. For a wide range of temperatures and pressures we find that hydrogen will be adsorbed at the surface, preferentially with a coverage of 1/2 monolayer. At high temperatures and low pressures the hydrogen can be removed and a structure with 1/4 of the surface oxygen atoms missing becomes the most stable one. The clean, defect-free surface can only exist in an oxygen-rich environment with a very low hydrogen partial pressure. However, since we find that the dissociative adsorption of molecular hydrogen and water (if also the Zn-terminated surface is present) is energetically very preferable, it is very unlikely that a clean, defect-free (000-1)-O surface can be observed in experiment.Comment: 10 pages, 4 postscript figures. Uses REVTEX and epsf macro

    CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load: a longitudinal cohort study from COHERE.

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    BACKGROUND: Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load. METHODS AND FINDINGS: Using data from the Collaboration of Observational HIV Epidemiological Research Europe (2010 merger), we assessed the risk of a new AIDS-defining event or death in successfully treated patients. We accumulated episodes of viral suppression for each patient while on cART, each episode beginning with the second of two consecutive plasma viral load measurements 500 copies/µl, the first of two consecutive measurements between 50-500 copies/µl, cART interruption or administrative censoring. We used stratified multivariate Cox models to estimate the association between time updated CD4 cell count and a new AIDS event or death or death alone. 75,336 patients contributed 104,265 suppression episodes and were suppressed while on cART for a median 2.7 years. The mortality rate was 4.8 per 1,000 years of viral suppression. A higher CD4 cell count was always associated with a reduced risk of a new AIDS event or death; with a hazard ratio per 100 cells/µl (95% CI) of: 0.35 (0.30-0.40) for counts <200 cells/µl, 0.81 (0.71-0.92) for counts 200 to <350 cells/µl, 0.74 (0.66-0.83) for counts 350 to <500 cells/µl, and 0.96 (0.92-0.99) for counts ≥500 cells/µl. A higher CD4 cell count became even more beneficial over time for patients with CD4 cell counts <200 cells/µl. CONCLUSIONS: Despite the low mortality rate, the risk of a new AIDS event or death follows a CD4 cell count gradient in patients with viral suppression. A higher CD4 cell count was associated with the greatest benefit for patients with a CD4 cell count <200 cells/µl but still some slight benefit for those with a CD4 cell count ≥500 cells/µl

    How to minimise the effect of tumour cell content in detection of aberrant genetic markers in neuroblastoma

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    Background:Clinical heterogeneity reflects the complexity of genetic events associated with neuroblastoma (NB). To identify the status of all described genetic loci with possible prognostic interest, high-throughput approaches have been used, but only with tumour cell content >60%. In some tumours, necrotic, haemorrhagic and/or calcification areas influence the low amount of neuroblasts. We evaluated the effect of tumour cell content in the detection of relevant aberrant genetic markers (AGM) diagnosed by fluorescence in situ hybridisation (FISH) on tissue microarrays (TMA) in NB.Methods:Two hundred and thirty-three MYCN non-amplified primary NB included in 12 TMAs were analysed.Results:Presence of AGM reduced event-free survival (EFS) (P=0.004) as well as overall survival (OS) (P=0.004) of patients in the whole cohort. There were no differences in prognostic impact of presence of AGM according to tumour cell content.Conclusion:We propose the use of FISH to diagnose AGM of all NB samples having the above-mentioned areas to determine patient risk

    Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results

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    Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio (PNJL) models, we investigate how the location of the critical endpoint in the QCD phase diagram depends on the strenght of the vector meson coupling, as well as the Polyakov-loop (PL) potential and the form factors of the covariant model. The latter are constrained by lattice QCD data for the quark propagator. The strength of the vector coupling is adjusted such as to reproduce the slope of the pseudocritical temperature for the chiral phase transition at low chemical potential extracted recently from lattice QCD simulations. Our study supports the existence of a critical endpoint in the QCD phase diagram albeit the constraint for the vector coupling shifts its location to lower temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to appear), references adde

    11q deletion or ALK activity curbs DLG2 expression to maintain an undifferentiated state in neuroblastoma

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    High-risk neuroblastomas typically display an undifferentiated or poorly differentiated morphology. It is therefore vital to understand molecular mechanisms that block the differentiation process. We identify an important role for oncogenic ALK-ERK1/2-SP1 signaling in the maintenance of undifferentiated neural crest-derived progenitors through the repression of DLG2, a candidate tumor suppressor gene in neuroblastoma. DLG2 is expressed in the murine "bridge signature'' that represents the transcriptional transition state when neural crest cells or Schwann cell precursors differentiate to chromaffin cells of the adrenal gland. We show that the restoration of DLG2 expression spontaneously drives neuroblastoma cell differentiation, high-lighting the importance of DLG2 in this process. These findings are supported by genetic analyses of high-risk 11q deletion neuroblastomas, which identified genetic lesions in the DLG2 gene. Our data also suggest that further exploration of other bridge genes may help elucidate the mechanisms underlying the differentiation of NC-derived progenitors and their contribution to neuroblastomas
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