749 research outputs found

    What do students know and understand about the Holocaust? Evidence from English secondary schools

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    This research report has been written under the auspices of the University College London (UCL) Centre for Holocaust Education. The Centre is part of the UCL Institute of Education – currently the world’s leading university for education – and is comprised of a team of researchers and educators from a variety of different disciplinary fields. The Centre works in partnership with the Pears Foundation who, together with the Department for Education, have co-funded its operation since it was first established in 2008. A centrally important principle of all activity based at the UCL Centre for Holocaust Education is that, wherever possible, classroom practice should be informed by academic scholarship and relevant empirical research. In 2009, Centre staff published an extensive national study of secondary school teachers’ experience of and attitudes towards teaching about the Holocaust (Pettigrew et al. 2009). This new report builds on that earlier work by critically examining English school students’ knowledge and understanding of this history. In both cases, research findings have been – and will continue to be – used to develop an innovative and ground-breaking programme of continuing professional development (CPD) for teachers and educational resources that are uniquely responsive to clearly identified classroom needs. The UCL Centre for Holocaust Education is the only institution of its kind, both within the United Kingdom and internationally, where pioneering empirical research is placed at the heart of work to support teachers and their students encountering this profoundly important yet complex and challenging subject in schools. The Centre offers a wide-ranging educational programme appropriate to teachers at all stages of their careers through a carefully constructed ‘pathway of professional development’. This provides opportunities for individuals to progressively deepen their knowledge and improve their practice. It offers a national programme of Initial Teacher Education in Holocaust education and a variety of in-depth and subject-specific CPD. In addition, the Centre also offers online distance learning facilities, including a fully accredited taught Masters-level module The Holocaust in the Curriculum. Through its Beacon School programme, Centre staff work intensively with up to 20 schools across England each year in order to recognise and further develop exemplary whole-school approaches and effective pedagogy. All of the courses and classroom materials developed by the UCL Centre for Holocaust Education are available free of charge to teachers working in England’s statefunded secondary schools. Further information can be found at www.ioe.ac.uk/holocaust

    Perfect absorption in GaAs metasurfaces near the bandgap edge

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    Perfect optical absorption occurs in a metasurface that supports two degenerate and critically-coupled modes of opposite symmetry. The challenge in designing a perfectly absorbing metasurface for a desired wavelength and material stems from the fact that satisfying these conditions requires multi-dimensional optimization often with parameters affecting optical resonances in non-trivial ways. This problem comes to the fore in semiconductor metasurfaces operating near the bandgap wavelength, where intrinsic material absorption varies significantly. Here we devise and demonstrate a systematic process by which one can achieve perfect absorption in GaAs metasurfaces for a desired wavelength at different levels of intrinsic material absorption, eliminating the need for trial and error in the design process. Using this method, we show that perfect absorption can be achieved not only at wavelengths where GaAs exhibits high absorption, but also at wavelengths near the bandgap edge. In this region, absorption is enhanced by over one order of magnitude compared a layer of unstructured GaAs of the same thickness

    Gel chromatographic characterization of immunoreactive adrenocorticotropin in patients with ACTH hypersecretion

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    We investigated the molecular size of circulating immunoreactive ACTH by gel chromatography in patients with ACTH hypersecretion due to various disorders of the hypothalamic-pituitary-adrenal axis. 4 patients with Addison's disease, 2 with Nelson's syndrome, 4 with Cushing's disease, 6 with the ectopic ACTH syndrome (2 bronchial carcinoma, 1 medullary carcinoma, 1 metastatic islett cell carcinoma, 1 benign bronchial carcinoid and 1 patient with occult ectopic Cushing's syndrome) and 1 patient with hypersecretion of ACTH from a clinically nonfunctioning pituitary adenoma were studied. Analysis of the molecular size of immunoreactive ACTH was performed by gel chromatography on a Sephadex G-75 column (superfine, 100×1.5 cm) equilibrated with 1% formic acid. 2 ml fractions were collected and evaporated to dryness. The ACTH content of the recovered samples was determined by RIA. In Addison's disease, Nelson's syndrome and Cushing's disease the plasma showed a single peak of ACTH immunoreactivity at the expected position of 1–39 ACTH. In the ectopic ACTH syndrome the plasma of 4 patients revealed at chromatography at least one other peak eluting between the void volume and 1–39 ACTH suggestive of a high molecular weight form of ACTH whereas plasma of 2 patients showed only a single ACTH peak at the position of labeled 1–39 ACTH. The patient with a clinically non-functioning pituitary adenoma revealed a gel filtration pattern similar to the patients with ectopic ACTH syndrom and secretion of high molecular weight ACTH. We conclude that secretion of high molecular weight forms of ACTH is not a unique feature of the ectopic ACTH syndrome. It may therefore not serve as a marker of the ectopic Cushing's syndrome in the differential diagnosis of the ACTH dependent Cushing's syndrome. Vice versa, lack of high molecular weight ACTH does not exclude an ectopic source of ACTH secretion as cause of Cushing's syndrome

    Nonlinear Terahertz Generation in Semiconductor Metasurfaces

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    We demonstrate ultra-thin semiconductor metasurfaces for generation of THz pulses. By investigating the dependence of the THz amplitude and phase on excitation field polarization and crystal orientation, we deduce that the underlying THz emission mechanism in metasurfaces differs from bulk semiconductor wafers with second order nonlinearity playing a dominant role. The metasurface enables control of the THz phase and can therefore be used to spatially structure the THz emitted field. We use this effect to design and demonstrate a metasurface which simultaneously emits and focusses THz pulses

    Terahertz Generation from GaAs Metasurfaces: Role of Surface Nonlinearity

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    We show that a GaAs metasurface can generate THz radiation with comparable efficiency to a bulk GaAs crystal. We attribute the enhanced generation to second order nonlinearity with the surface making a strong contribution

    Human Peripheral Blood Mononuclear Cells Exhibit Heterogeneous CD52 Expression Levels and Show Differential Sensitivity to Alemtuzumab Mediated Cytolysis

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    Alemtuzumab is a monoclonal antibody that targets cell surface CD52 and is effective in depleting lymphocytes by cytolytic effects in vivo. Although the cytolytic effects of alemtuzumab are dependent on the density of CD52 antigen on cells, there is scant information regarding the expression levels of CD52 on different cell types. In this study, CD52 expression was assessed on phenotypically distinct subsets of lymphoid and myeloid cells in peripheral blood mononuclear cells (PBMCs) from normal donors. Results demonstrate that subsets of PBMCs express differing levels of CD52. Quantitative analysis showed that memory B cells and myeloid dendritic cells (mDCs) display the highest number while natural killer (NK) cells, plasmacytoid dendritic cells (pDCs) and basophils have the lowest number of CD52 molecules per cell amongst lymphoid and myeloid cell populations respectively. Results of complement dependent cytolysis (CDC) studies indicated that alemtuzumab mediated profound cytolytic effects on B and T cells with minimal effect on NK cells, basophils and pDCs, correlating with the density of CD52 on these cells. Interestingly, despite high CD52 levels, mDCs and monocytes were less susceptible to alemtuzumab-mediated CDC indicating that antigen density alone does not define susceptibility. Additional studies indicated that higher expression levels of complement inhibitory proteins (CIPs) on these cells partially contributes to their resistance to alemtuzumab mediated CDC. These results indicate that alemtuzumab is most effective in depleting cells of the adaptive immune system while leaving innate immune cells relatively intact
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