9,281 research outputs found
Fluid flow analysis by a modified, white light, Lau interferometer
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
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
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
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
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On Birthing Dancing Stars: The Need for Bounded Chaos in Information Interaction
While computers causing chaos is acommon social trope, nearly the entirety of the history of computing is dedicated to generating order. Typical interactive information retrieval tasks ask computers to support the traversal and exploration of large, complex information spaces. The implicit assumption is that they are to support users in simplifying the complexity (i.e. in creating order from chaos). But for some types of task, particularly those that involve the creative application or synthesis of knowledge or the creation of new knowledge, this assumption may be incorrect. It is increasingly evident that perfect order—and the systems we create with it—support highly-structured information tasks well, but provide poor support for less-structured tasks.We need digital information environments that help create a little more chaos from order to spark creative thinking and knowledge creation. This paper argues for the need for information systems that offerwhat we term ‘bounded chaos’, and offers research directions that may support the creation of such interface
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Getting creative in everyday life: Investigating arts and crafts hobbyists' information behavior
While there has been increasing interest in how creative professionals find information to drive creative outputs, previous information behavior research has largely ignored how arts and crafts hobbyists look for information sources in their everyday lives. To fill this literature gap, we conducted interviews and observations with arts and crafts hobbyists to find out how they conceive potential DIY projects. The findings highlight three themes: the dearth of human sources, the prevalence of domain-specific information, and the use of self-curated information. In addition to empirical results, this work also broadens the understanding of information behavior in an arts and crafts context by studying populations beyond professional artists
Employer Sanctions: The impact of workplace raids and fines on undocumented migrants and ethnic enclave employers
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
We describe the application of the `shapelet' linear decomposition of galaxy
images to multi-wavelength morphological classification using the
and -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 color
and find the shapelet method to be superior in separating galaxies.
Furthermore, we find evidence that the decision boundary may not be
optimal for separation between early and late type galaxies, and suggest that
the optimal cut may be .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
Comparing SCUBA-2 and ALMA Selections of Faint DSFGs in Abell 2744
We make a comparison of deep SCUBA-2 450 m and 850 m imaging on the
massive lensing cluster field Abell 2744 with Atacama Large
Millimeter/submillimeter Array (ALMA) 1.2 mm data. Our primary goal is to
assess how effective the wider-field SCUBA-2 sample, in combination with red
JWST priors, is for finding faint dusty star-forming galaxies (DSFGs) compared
to the much more expensive mosaicked ALMA observations. We cross-match our
previously reported direct () SCUBA-2 sample and red JWST NIRCam
prior-selected () SCUBA-2 sample to direct ALMA sources from the
DUALZ survey. We find that roughly 95% are confirmed by ALMA. The red priors
also allow us to probe deeper in the ALMA image. Next, by measuring the 450
m and 850 m properties of the full ALMA sample, we show that 46/69 of
the ALMA sources are detected at 850 m and 24/69 are detected at 450
m in the SCUBA-2 images, with a total detection fraction of nearly 75%.
All of the robust () ALMA sources that are not detected in at least
one SCUBA-2 band lie at 1.2 mm fluxes 0.6 mJy and are undetected
primarily due to the higher SCUBA-2 flux limits. We also find that the SCUBA-2
detection fraction drops slightly beyond , which we attribute to the
increasing 1.2 mm to 850 m and 1.2 mm to 450 m flux ratios combined
with the ALMA selection. The results emphasize the power of combining SCUBA-2
data with JWST colors to map the faint DSFG population.Comment: 12 pages, 6 figures, 2 tables. Accepted for publication in ApJ. v2:
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