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On the Transverse M5-Branes in Matrix Theory
Get PDFIt has been a long-standing problem how the transverse M5-branes are described in the matrix-model formulations of M-theory. We consider this problem for M-theory on the maximally supersymmetric pp-wave geometry, which admits transverse spherical M5-branes with zero light-cone energy. By using the localization, we directly analyze the strong coupling region of the corresponding matrix theory called the plane wave matrix model (PWMM). Under the assumption that the SO(6) scalars in PWMM become mutually commuting in the strong coupling region, we show that the eigenvalue density of the SO(6) scalars in PWMM exactly agrees with the shape of the spherical M5-branes in the decoupling limit. This result gives a strong evidence that the transverse M5-branes are indeed contained in the matrix theory and the theory realizes a second quantization of the M-theory
Better together: your village and your voice
Get PDFAt the Academic and Special Libraries Section AGM in 2007, Aoife Connolly and Margaret Irons found themselves becoming members of the A&SL committee. Fast forward 6 years and both decided to step down at the same time! But what happened in the intervening years? What have they done since? Were they #bettertogether?
Through their stories Aoife & Margaret will share the different paths that brought them to the A&SL committee, and beyond. Knowing that putting yourself forward to be part of committee is not always easy, they want to show how it can be done to the enrichment of your professional and personal life. Inspired by the conference theme Aoife & Margaret will outline how they became “Sociable Librarians” and the guises that title can take in careers and communities, behind the desk and out the door. This case study will focus on how as professionals we can come from different directions to form alliances, learn and share new skills making us #bettertogether and sending us forward with confidence and plans for the future. It will illustrate how finding your voice and your village can be daunting and dangerous – in the best possible ways
Multiple Coincident Eruptive Seismic Tremor Sources During the 2014-2015 Eruption at Holuhraun, Iceland
Get PDFWe analyze eruptive tremor during one of the largest effusive eruptions in historical times in Iceland (2014/15 Holuhraun eruption). Seismic array recordings are compared with effusion rates deduced from MODerate resolution Imaging Spectroradiometer (MODIS) recordings and ground video monitoring data and lead to the identification of three coexisting eruptive tremor sources. This contrasts other tremor studies that generally link eruptive tremor to only one source usually associated with the vent. The three sources are (i) a source that is stable in back azimuth and shows bursts with ramp-like decrease in amplitude at the beginning of the eruption. We link it to a process below the open vents where the bursts correlate with the opening of new vents and temporary increases in the lava fountaining height. (ii) a source moving by a few degrees per month while the tremor amplitude suddenly increases and decreases. Back azimuth and slowness correlate with the growing margins of the lava flow field whilst contact with a river led to fast increases of the tremor amplitude. (iii) a source moving by up to 25 degrees southwards in 4 days that cannot be related to any observed surface activity and might be linked to intrusions. We therefore suggest that eruptive tremor amplitudes/ energies are used with caution when estimating eruptive volumes, effusion rates or the eruption explosivity as multiple sources can coexist during the eruption phase. Our results suggest that arrays can monitor both the growth of a lava flow field and the activity in the vents
A Kind of Magic
Get PDFWe introduce the extended Freudenthal-Rosenfeld-Tits magic square based on six algebras: the reals R, complexes C, ternions T, quaternions H, sextonions S and octonions O. The sextonionic row/column of the magic square appeared previously and was shown to yield the non-reductive Lie algebras, sp_6_1/2, sl_6_1/2, so_12_1/2, so_12_3/4 and e_7_1/2, for R, C, H, S and O respectively. The fractional ranks are used to denote the semi-direct extension of the simple Lie algebra in question by a unique (up to equivalence) Heisenberg algebra. The ternionic row/column yields the non-reductive Lie algebras, sl_3_1/4, [sl_3 ⊕ sl_3]_1/4, [sl_3 ⊕ sl_3]_1/2, sl_6_1/4, sl_6_3/4 and e_6_1/4, for R, C, T, H, S and O respectively. The fractional ranks here are used to denote the semi-direct extension of the semi-simple Lie algebra in question by a unique (up to equivalence) nilpotent “Jordan” algebra. We present all possible real forms of the extended magic square. It is demonstrated that the algebras of the extended magic square appear quite naturally as the symmetries of supergravity Lagrangians. The sextonionic row (for appropriate choices of real forms) gives the non-compact global symmetries of the Lagrangian for the D = 3 maximal N = 16, magic N = 4 and magic non-supersymmetric theories, obtained by dimensionally reducing the D = 4 parent theories on a circle, with the graviphoton left undualised. In particular, the extremal intermediate non-reductive Lie algebra ẽ_7(7)_1/2 (which is not a subalgebra of e_8(8) ) is the non-compact global symmetry algebra of D = 3, N = 16 supergravity as obtained by dimensionally reducing D = 4, N = 8 supergravity with e_7(7) symmetry on a circle. On the other hand, the ternionic row (for appropriate choices of real forms) gives the non-compact global symmetries of the Lagrangian for the D = 4 maximal N = 8, magic N = 2 and magic non-supersymmetric theories, as obtained by dimensionally reducing the parent D = 5 theories on a circle. In particular, the Kantor-Koecher-Tits intermediate non-reductive Lie algebra e_6(6)_1/4 is the non-compact global symmetry algebra of D = 4, N = 8 supergravity as obtained by dimensionally reducing D = 5, N = 8 supergravity with e_6(6) symmetry on a circle
Are All Supergravity Theories Yang-Mills Squared?
Get PDFUsing simple symmetry arguments we classify the ungauged D=4, N=2 supergravity theories, coupled to both vector and hyper multiplets through homogeneous scalar manifolds, that can be built as the product of N=2 and N=0 matter-coupled Yang-Mills gauge theories. This includes all such supergravities with two isolated exceptions: pure supergravity and the T3 model
Optimal Lojasiewicz-Simon Inequalities and Morse-Bott Yang-Mills Energy Functions
Get PDFFor any compact Lie group G, we prove that the Yang–Mills energy function obeys an optimal gradient inequality of Łojasiewicz–Simon type (exponent 1/2) near the critical set of flat connections on a principal G-bundle over a closed Riemannian manifold of dimension d ≥ 2 and so its gradient flow converges at an exponential rate to that critical set. We establish this optimal Łojasiewicz–Simon gradient inequality by three different methods. Our first proof gives the most general result by direct analysis and relies on our extension of a theorem due to Uhlenbeck [86] that gives existence of a flat connection on a principal G-bundle supporting a connection with L^d/2 -small curvature, existence of a Coulomb gauge transformation, and W^1,p Sobolev distance estimates for p > 1. Our second proof proceeds by first establishing an optimal Łojasiewicz–Simon gradient inequality for abstract Morse–Bott functions on Banach manifolds, generalizing an earlier result due to the author and Maridakis [31, Theorem 4]. Our third proof establishes the optimal Łojasiewicz–Simon gradient inequality by direct analysis near a given flat connection that is a regular point of the curvature map. We prove similar results for the self-dual Yang–Mills energy function near regular anti-self-dual connections over closed Riemannian four-manifolds and for the full Yang–Mills energy function over closed Riemannian manifolds of dimension d ≥ 2, when known to be Morse–Bott at a given Yang–Mills connection
The death of Boand and the recensions of Dindṡenchas Érenn
Get PDFThe death of Boand is found in both prose and verse in the Dindṡenchas. Three poems, labelled
Boand I, II, and III by E.J. Gwynn, have survived in various sources. In the first section of this
paper, I provide an analysis of the relationship of these poems to one another. This section also
includes an edition and translation of a short poem, here called ‘Boand A’, from Oxford Bodl.
MS Laud 610, which has a close connection to Boand I. In the second section, I discuss changes
which occur between variants of the prose article on Boand. The outcome of the present enquiry
demonstrates how studying individual Dindṡenchas articles broadens our knowledge of the
dynamics and growth of the entire corpus. The results of this investigation also have an impact
on our understanding of the recensions of the Dindṡenchas