407 research outputs found

    Crystalline Fullerenes. Round Pegs in Square Holes

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    Crystalline Fullerenes. Round Pegs in Square Holes

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    Crystalline Fullerenes. Round Pegs in Square Holes

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    Good images, effective messages? Working with students and educators on academic practice understanding

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    Work at Northumbria University has focussed on activity that extends opportunities for students to engage directly with the skills development necessary for sound academic practice. This has included highly visual campaigns on the "Plagiarism trap", providing access to Turnitin plagiarism detection software, guides and sessions to highlight use of associated referencing tools. Sessions on a variety of topics, such as supporting study skills and reading originality reports, have been provided for students on taught, undergraduate and postgraduate programmes. This provision has included students working on collaborative partners' sites and also those on research programmes. Alongside the activities with students, "designing out" approaches have been embedded in staff development within the educator community at Northumbria. Formative use of Turnitin is integrated throughout programmes and academic practice development is formally recognised within the University Learning and Teaching Strategy's focus on information literacy. This article outlines and reviews these activities in a critical institutional context and evaluates responses from a variety of students and educators to determine how effective these measures have been

    Mask formulas for cograssmannian Kazhdan-Lusztig polynomials

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    We give two contructions of sets of masks on cograssmannian permutations that can be used in Deodhar's formula for Kazhdan-Lusztig basis elements of the Iwahori-Hecke algebra. The constructions are respectively based on a formula of Lascoux-Schutzenberger and its geometric interpretation by Zelevinsky. The first construction relies on a basis of the Hecke algebra constructed from principal lower order ideals in Bruhat order and a translation of this basis into sets of masks. The second construction relies on an interpretation of masks as cells of the Bott-Samelson resolution. These constructions give distinct answers to a question of Deodhar.Comment: 43 page

    Diffraction Symmetry in Crystalline, Close-Packed C60

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    We have grown crystals of the carbon structure C60 by sublimation. In contrast to solution-grown crystals, the sublimed crystals have long range order with no evidence of solvent inclusions. Sublimed C60 forms three dimensional, faceted crystals with a close-packed, face-centered cubic unit cell. We have refined a crystal structure using the "soccer ball" model of the C60 molecule. The results indicate that the C60 molecule has the expected spherical shape, however the data are not sufficiently accurate to unambiguously determine atomic positions

    Optical and X-ray correlations during the 2015 outburst of the black hole V404 Cyg

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    We present a serendipitous multiwavelength campaign of optical photometry simultaneous with Integral X-ray monitoring of the 2015 outburst of the black hole V404 Cyg. Large-amplitude optical variability is generally correlated with X-rays, with lags of order a minute or less compatible with binary light travel time-scales or jet ejections. Rapid optical flaring on time-scales of seconds or less is incompatible with binary light-travel time-scales and has instead been associated with synchrotron emission from a jet. Both this rapid jet response and the lagged and smeared one can be present simultaneously. The optical brightness is not uniquely determined by the X-ray brightness, but the X-ray/optical relationship is bounded by a lower envelope such that at any given optical brightness there is a maximum X-ray brightness seen. This lower envelope traces out a Fopt∝F0.54X relation that can be approximately extrapolated back to quiescence. Rapid optical variability is only seen near this envelope, and these periods correspond to the hardest hard X-ray colours. This correlation between hard X-ray colour and optical variability (and anticorrelation with optical brightness) is a novel finding of this campaign, and apparently a facet of the outburst behaviour in V404 Cyg. It is likely that these correlations are driven by changes in the central accretion rate and geometry
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