4,184 research outputs found

    Deployment and Impact of Support Staff in Schools : The Impact of Support Staff in Schools (Results from Strand 2, Wave 2)

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    This study was designed to obtain up to date and reliable data on the deployment and characteristics of support staff and the impact of support staff on pupil outcomes and teacher workloads. The study covered schools in England and Wales. It involved large scale surveys (Strand 1), followed by a multi-method and multi informant approach (Strand 2). It provided detailed baseline data by which to assess change and progress over time. It sought to understand the processes in schools which lead to the effective use of support staff. The DISS project was funded by the Department for Children, Schools and Families (DCSF) and Welsh Assembly Government (WAG)

    Effect of Inclination on Pressure Drop in Large Flattened-Tube Steam Condensers

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    This paper presents the experimental study of the inclination effect on condensation pressure drop in a large-scale flattened tube used in an Air-Cooled Condenser (ACC) for steam. Slightly-superheated steam with mass flux of 6.8 kg m-2 s-1 was condensed inside a 10.7 m long, flattened half-tube with inclination angle varied from horizontal to 13.2˚. A uniform velocity profile of 2.03 ± 0.12 m s-1 was imposed on the air side to extract heat from the steam. Initial two-phase pressure drop measurements and flow visualization showed a reduction of pressure drop due to improvement in the gravity-assisted drainage of condensate inside the tube, although improvement was only seen at an early stage of inclination. To create a visualization window, the tube was cut in half, and thus a model that accounts for the differences in tube material and size between the real, full, flattened condenser tube and test tube was developed and validated in the single-phase flow scenario. This model enables the prediction of pressure drop under different inclination configurations in the actual ACC in power plants by using the experimental results obtained in this study. Heat transfer results are presented in a companion paper.

    Heat Transfer and Visualization in Large Flattened-Tube Condensers with Variable Inclination

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    An experimental study of convective condensation of steam in a large, inclined, finned tube is presented. This study extends previous work in the field on inclined, convective condensation in small, round tubes to large, non-circular tubes with low inlet mass flux of vapor. The steel condenser tube in this study was designed for use in a power-plant air-cooled-condenser array with forced convection of air. The tube was cut in half lengthwise and covered with a polycarbonate viewing window to allow simultaneous visualization and heat transfer measurements. The half tube test section had inner dimensions of 214 mm x 6.3 mm and a length of 10.72 m. This study investigated heat transfer results for a mass flux of steam of 6.8 kg/m2-s over a range of inclination angles. The angle of inclination of the condenser tube was varied from 0.3o (horizontal) to 13.2o downward flow. The experiments were performed with uniform crossflowing air with velocity of 2.0 m/s. Both dropwise and filmwise condensation were observed on the tube wall, and depth of the condensate river at tube bottom was seen to decrease with an increase in inclination angle. Average steam-side heat transfer coefficient was shown to increase with an increase in inclination angle.  However, average steam-side heat transfer coefficient was much lower than the predictions of both vertical flat-plate Nusselt condensation, as well as Kroger’s correlation for condensation in air-cooled condensers.  Overall, the results suggest that an improvement in steam-side heat transfer performance can be achieved by varying the tube inclination angle. Pressure drop results are presented in a companion paper

    The cell adhesion molecule Fasciclin2 regulates brush border length and organization in Drosophila renal tubules

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    Multicellular organisms rely on cell adhesion molecules to coordinate cell–cell interactions, and to provide navigational cues during tissue formation. In Drosophila, Fasciclin 2 (Fas2) has been intensively studied due to its role in nervous system development and maintenance; yet, Fas2 is most abundantly expressed in the adult renal (Malpighian) tubule rather than in neuronal tissues. The role Fas2 serves in this epithelium is unknown. Here we show that Fas2 is essential to brush border maintenance in renal tubules of Drosophila. Fas2 is dynamically expressed during tubule morphogenesis, localizing to the brush border whenever the tissue is transport competent. Genetic manipulations of Fas2 expression levels impact on both microvilli length and organization, which in turn dramatically affect stimulated rates of fluid secretion by the tissue. Consequently, we demonstrate a radically different role for this well-known cell adhesion molecule, and propose that Fas2-mediated intermicrovillar homophilic adhesion complexes help stabilize the brush border

    The Stargazin-Related Protein {gamma}7 Interacts with the mRNA-Binding Protein Heterogeneous Nuclear Ribonucleoprotein A2 and Regulates the Stability of Specific mRNAs, Including CaV2.2

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    The role(s) of the novel stargazin-like {gamma}-subunit proteins remain controversial. We have shown previously that the neuron-specific {gamma}7 suppresses the expression of certain calcium channels, particularly CaV2.2, and is therefore unlikely to operate as a calcium channel subunit. We now show that the effect of {gamma}7 on CaV2.2 expression is via an increase in the degradation rate of CaV2.2 mRNA and hence a reduction of CaV2.2 protein level. Furthermore, exogenous expression of {gamma}7 in PC12 cells also decreased the endogenous CaV2.2 mRNA level. Conversely, knockdown of endogenous {gamma}7 with short-hairpin RNAs produced a reciprocal enhancement of CaV2.2 mRNA stability and an increase in endogenous calcium currents in PC12 cells. Moreover, both endogenous and expressed {gamma}7 are present on intracellular membranes, rather than the plasma membrane. The cytoplasmic C terminus of {gamma}7 is essential for all its effects, and we show that {gamma}7 binds directly via its C terminus to a heterogeneous nuclear ribonucleoprotein (hnRNP A2), which also binds to a motif in CaV2.2 mRNA, and is associated with native CaV2.2 mRNA in PC12 cells. The expression of hnRNP A2 enhances CaV2.2 IBa, and this enhancement is prevented by a concentration of {gamma}7 that alone has no effect on IBa. The effect of {gamma}7 is selective for certain mRNAs because it had no effect on {alpha}2{delta}-2 mRNA stability, but it decreased the mRNA stability for the potassium-chloride cotransporter, KCC1, which contains a similar hnRNP A2 binding motif to that in CaV2.2 mRNA. Our results indicate that {gamma}7 plays a role in stabilizing CaV2.2 mRNA

    Fibronectin-conjugated thermoresponsive nanobridges generate three dimensional human pluripotent stem cell cultures for differentiation towards the neural lineages.

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    Production of 3-dimensional neural progenitor cultures from human pluripotent stem cells offers the potential to generate large numbers of cells. We utilised our nanobridge system to generate 3D hPSC aggregates for differentiation towards the neural lineage, and investigate the ability to passage aggregates while maintaining cells at a stem/progenitor stage. Over 38 days, aggregate cultures exhibited upregulation and maintenance of neural-associated markers and demonstrated up to 10 fold increase in cell number. Aggregates undergoing neural induction in the presence or absence of nanobridges demonstrated no differences in marker expression, proliferation or viability. However, aggregates formed without nanobridges were statistically significantly fewer and smaller by passage 3. Organoids, cultured from aggregates, and treated with retinoic acid or rock inhibitor demonstrated terminal differentiation as assessed by immunohistochemistry. These data demonstrate that nanobridge 3D hPSC can differentiate to neural stem/progenitor cells, and be maintained at this stage through serial passaging and expansion

    The Use of Cellomics to Study Enterocyte Cytoskeletal Proteins in Coeliac Disease Patients

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    Coeliac disease is characterised by inflammation of small intestinal mucosa accompanied by abnormal villous architecture. It is now accepted that some patients with positive coeliac serology tests may have minor mucosal lesions that may not be apparent on routine histopathological analysis. The aim of the study was to perform detailed examination of enterocyte morphology and cytoskeletal structures using a high content analysis technology. Duodenal biopsies from 14 untreated and 10 treated coeliac patients and from 20 non-coeliac controls were examined. Tissue sections from six patients (study group subjects) before and after the development of gluten-sensitive enteropathy were also investigated. Immunohistochemical studies were performed on paraffin-embedded sections using an anti-α-tubulin antibody. Significant differences in enterocyte morphology and intracellular cytoskeletal structures were demonstrated in patients with proven coeliac disease and in the study group subjects. These changes were present in study group biopsies before evidence of enteropathy, as assessed by routine microscopy. This is the first study to demonstrate detailed characteristics of enterocyte morphology in coeliac patients using a high content analysis approach. The use of this technology allows a quantitative analysis of enterocyte intracellular structures from routine biopsy material and permits detection of subtle changes that precede the characteristic histological lesion
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