9,245 research outputs found

    Fluid flow analysis by a modified, white light, Lau interferometer

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    This paper presents a sharp focussing schlieren system based upon a modified Lau interferometer. A method of reducing the depth of focus of the system is demonstrated and the development of the system to study large fields of view by theincorporation of flexible membrane mirrors is discussed

    Identification of solar nebula condensates in interplanetary dust particles and unequilibrated ordinary chondrites

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    Orthopyroxene and olivine grains, low in FeO, but containing MnO contents up to 5 wt percent were found in interplanetary dust particles (IDP) collected in the stratosphere. The majority of olivines and pyroxenes in meteorites contain less than 0.5 wt percent MnO. Orthopyroxenes and olivines high in Mn and low in FeO have only been reported from a single coarse grained chondrule rim in the Allende meteorite and from a Tieschitz matrix augite grain. The bulk MnO contents of the extraterrestrial dust particles with high MnO olivines and pyroxenes are close to CI chondrite abundances. High MnO, low FeO olivines and orthopyroxenes were also found in the matrix of Semarkona, an unequilibrated ordinary chondrite. This may indicate a related origin for minerals in extraterrestrial dust particles and in the matrix of unequilibrated ordinary chondrites

    Combatting conspiracies in the classroom: Teacher strategies and perceived outcomes

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    This article draws on data from a specially commissioned representative survey, which elicited responses from 7691 teachers in primary and secondary schools in England, to examine how teachers perceive young people's engagement with a variety of different conspiracy theories in school settings and how they respond to them. Approximately 40% of teachers report encountering students who supported conspiracy theories. In response, teachers use a wide range of contradictory strategies, including opening up discussion, closing it down, challenging students in class and reporting individuals as safeguarding concerns. The research evidence suggests that several of these strategies are likely to be ineffective or even backfire to reinforce conspiracy thinking. Unsurprisingly then, few teachers report successful responses. The article concludes that the evidence of possible negative impacts of unprepared teachers confronting conspiracy theories at school means that teachers need to be better equipped through training, support and further research

    Transmission electron microscopy of an interplanetary dust particle with links to CI chondrites

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    The majority of hydrated interplanetary dust particles (IDPs) have compositions that resemble CI and CM chondrites, however, their mineralogies are most similar to the fine grained material in certain altered type-3 carbonaceous and ordinary chondrites. During the transmission electron microscope studies of hydrated IDPs, a unique particle was discovered whose mineralogy is very similar to that reported from CI chondrites. W7013F5 is the first IDP whose mineralogy and chemistry approximates that of CI chondrites. The similarity in mineralogy and mineral chemistry suggests that W7013F5 was altered under conditions similar to those that existed on the CI parent bodies

    Employer Sanctions: The impact of workplace raids and fines on undocumented migrants and ethnic enclave employers

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    The context of this article is the use of employer sanctions, in the form of raids and fines on businesses found to be employing people who do not have permission to work in the UK, as a method of in-border immigration control. Drawing on qualitative interviews with undocumented migrants and ethnic enclave employers in London, this article examines the impact of sanctions from the perspectives of those who have been or are most likely to be affected. More specifically the article sheds light on individual experiences of and strategies against immigration enforcement raids, and the effect of raids on the labour market, conditions of work and more widely, on local community relations. The paper concludes that there is a disjuncture between the real impact of sanctions and at least some of the stated policy aims. </jats:p

    Morphological Classification of Galaxies by Shapelet Decomposition in the Sloan Digital Sky Survey II: Multiwavelength Classification

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    We describe the application of the `shapelet' linear decomposition of galaxy images to multi-wavelength morphological classification using the u,g,r,i,u,g,r,i, and zz-band images of 1519 galaxies from the Sloan Digital Sky Survey. We utilize elliptical shapelets to remove to first-order the effect of inclination on morphology. After decomposing the galaxies we perform a principal component analysis on the shapelet coefficients to reduce the dimensionality of the spectral morphological parameter space. We give a description of each of the first ten principal component's contribution to a galaxy's spectral morphology. We find that galaxies of different broad Hubble type separate cleanly in the principal component space. We apply a mixture of Gaussians model to the 2-dimensional space spanned by the first two principal components and use the results as a basis for classification. Using the mixture model, we separate galaxies into three classes and give a description of each class's physical and morphological properties. We find that the two dominant mixture model classes correspond to early and late type galaxies, respectively. The third class has, on average, a blue, extended core surrounded by a faint red halo, and typically exhibits some asymmetry. We compare our method to a simple cut on u−ru-r color and find the shapelet method to be superior in separating galaxies. Furthermore, we find evidence that the u−r=2.22u-r=2.22 decision boundary may not be optimal for separation between early and late type galaxies, and suggest that the optimal cut may be u−r∼2.4u-r \sim 2.4.Comment: 42 pages, 18 figs, revised version in press at AJ. Some modification to the technique, more discussion, addition/deletion/modification of several figures, color figures have been added. A high resolution version may be obtained at http://bllac.as.arizona.edu/~bkelly/shapelets/shapelets_ugriz.ps.g
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