1,184 research outputs found
Charges of Exceptionally Twisted Branes
The charges of the exceptionally twisted (D4 with triality and E6 with charge
conjugation) D-branes of WZW models are determined from the microscopic/CFT
point of view. The branes are labeled by twisted representations of the affine
algebra, and their charge is determined to be the ground state multiplicity of
the twisted representation. It is explicitly shown using Lie theory that the
charge groups of these twisted branes are the same as those of the untwisted
ones, confirming the macroscopic K-theoretic calculation. A key ingredient in
our proof is that, surprisingly, the G2 and F4 Weyl dimensions see the simple
currents of A2 and D4, respectively.Comment: 19 pages, 2 figures, LaTex2e, complete proofs of all statements,
updated bibliograph
On the Classification of Diagonal Coset Modular Invariants
We relate in a novel way the modular matrices of GKO diagonal cosets without
fixed points to those of WZNW tensor products. Using this we classify all
modular invariant partition functions of
for all positive integer level , and for all and infinitely many (in fact, for
each a positive density of ). Of all these classifications, only that
for had been known. Our lists include many
new invariants.Comment: 24 pp (plain tex
Nonlinear field-dependence and f-wave interactions in superfluid 3He
We present results of transverse acoustics studies in superfluid ^{3}He-B at
fields up to 0.11 T. Using acoustic cavity interferometry, we observe the
Acoustic Faraday Effect for a transverse sound wave propagating along the
magnetic field, and we measure Faraday rotations of the polarization as large
as 1710^{\circ}. We use these results to determine the Zeeman splitting of the
Imaginary Squashing mode, an order parameter collective mode with total angular
momentum J=2. We show that the pairing interaction in the f-wave channel is
attractive at a pressure of P=6 bar. We also report nonlinear field dependence
of the Faraday rotation at frequencies substantially above the mode frequency
not accounted for in the theory of the transverse acoustic dispersion relation
formulated for frequencies near the mode. Consequently, we have identified the
region of validity of the theory allowing us to make corrections to the
analysis of Faraday rotation experiments performed in earlier work.Comment: 7 pages, 5 figure
On the existence of Einstein oscillators and thermal conductivity in bulk metallic glass
Low-temperature specific heat and thermal conductivity of bulk metallic glasses are measured to identify the primary vibrational modes associated with their unique structures. An Einstein-type localized vibrational mode with an Einstein temperature of 112âK112K is found in bulk metallic glass Ni59.5Nb33.6Sn6.9Ni59.5Nb33.6Sn6.9. This localized vibrational mode causes resonant scattering of phonons and results in the localization of phonons which leaves the phonon hopping conduction the limiting mechanism of thermal transport in bulk metallic glass Ni59.5Nb33.6Sn6.9Ni59.5Nb33.6Sn6.9 at high temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87816/2/031924_1.pd
The phrase 'The Great War' in british discourse during world war one
The association of the term âThe Great Warâ with World War One, if it began 100 years ago, could be seen as telling, not only about attitudes at the time (and whether it meant âjolly bigâ or âjolly goodâ), but about our retrospective attitudes to those who were involved. Through an examination of propaganda, periodicals, political statements and specific pre-war literature, an assumption that as a phrase it is indicative of jingoistic and bellicose hysteria generated by influential politicians for the gullible citizens of whichever participant nation, can be shown as a misleading simplification. Instead, with a concentration on Britain, a study of its use by statesmen such as Asquith and Lloyd George, the very particular circumstances under which it appeared in Punch magazine, and the overt zeal some advocates of war with Germany displayed from several years before 1914, is revealing of very different public standpoints among supporters of the war.info:eu-repo/semantics/publishedVersio
Suitability of mycorrhiza-defective mutant/wildtype plant pairs (Solanum lycopersicum L. cv Micro-Tom) to address questions in mycorrhizal soil ecology
Despite the importance of arbuscular mycorrhizal fungi (AMF) to ecosystem processes, few experimental tools are available to quantify AMF contributions to process rates. In this study we examine the efficacy of an experimental system consisting of wildtype (WT) and different non-mycorrhizal (Mycâ) genotype pairs of tomato (Solanum lycopersicum L.), specifically focusing on cv Micro-Tom. Two conditions necessary to make such a system useful were examined; (1) that the Mycâ genotype(s) do not get colonized in a full soil AMF community background, while the WT does, and B) that there are no non-target effects of the Mycâ phenotype on soil microbes. We assessed the second condition by growing Mycâ genotypes and WT in non-mycorrhizal soil, monitoring plant growth (root, shoot biomass; root length; root diameter size distribution) and soil microbial community structure (PLFA analysis) as indicators of any changes in root tissue quality or rhizodeposition. All tested Mycâ genotypes showed a drastically reduced colonization in mycorrhizal soil. However, in non-mycorrhizal soil, M161 had greater root biomass and M20 greater microbial biomass compared to WT. Only one of the Mycâ mutants examined fully met the criteria. We conclude that the BC1/WT pair is a powerful experimental system and recommend caution when using Mycâ mutants in mycorrhizal ecology
Topology of Event Horizons and Topological Censorship
We prove that, under certain conditions, the topology of the event horizon of
a four dimensional asymptotically flat black hole spacetime must be a 2-sphere.
No stationarity assumption is made. However, in order for the theorem to apply,
the horizon topology must be unchanging for long enough to admit a certain kind
of cross section. We expect this condition is generically satisfied if the
topology is unchanging for much longer than the light-crossing time of the
black hole. More precisely, let be a four dimensional asymptotically flat
spacetime satisfying the averaged null energy condition, and suppose that the
domain of outer communication \C_K to the future of a cut of \Sm is
globally hyperbolic. Suppose further that a Cauchy surface for \C_K
is a topological 3-manifold with compact boundary in , and
is a compact submanifold of \bS with spherical boundary in (and
possibly other boundary components in ). Then we prove that the homology
group must be finite. This implies that either
consists of a disjoint union of 2-spheres, or is nonorientable and
contains a projective plane. Further,
\partial\S=\partial\Ip[K]\cap\partial\Im[\Sp], and will be
a cross section of the horizon as long as no generator of \partial\Ip[K]
becomes a generator of \partial\Im[\Sp]. In this case, if is orientable,
the horizon cross section must consist of a disjoint union of 2-spheres.}Comment: 11 pages, plain latex (minor revision: replaced by its
closure in various places.
On the complete classification of the unitary N=2 minimal superconformal field theories
Aiming at a complete classification of unitary N=2 minimal models (where the
assumption of space-time supersymmetry has been dropped), it is shown that each
modular invariant candidate of a partition function for such a theory is indeed
the partition function of a minimal model. A family of models constructed via
orbifoldings of either the diagonal model or of the space-time supersymmetric
exceptional models demonstrates that there exists a unitary N=2 minimal model
for every one of the allowed partition functions in the list obtained from
Gannon's work.
Kreuzer and Schellekens' conjecture that all simple current invariants can be
obtained as orbifolds of the diagonal model, even when the extra assumption of
higher-genus modular invariance is dropped, is confirmed in the case of the
unitary N=2 minimal models by simple counting arguments.Comment: 53 pages; Latex; minor changes in v2: intro expanded, references
added, typos corrected, footnote added on p31; renumbering of sections; main
theorem reformulated for clarity, but contents unchanged. Minor revisions in
v3: typos corrected, footnotes 5, 6 added, lemma 1 and section 3.3.2
rewritten for greater generality, section 3.3 review removed. To appear in
Comm. Math. Phy
Good images, effective messages? Working with students and educators on academic practice understanding
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
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