22,359,548 research outputs found
Common Medieval Pigments
This paper discusses the pigments used in medieval manuscripts. Specific types of pigments that are examined are earths, minerals, manufactured, and organics. It also focuses on both destructive and non-destructive methods for identifying medieval pigments
A worldsheet extension of O(d,d;Z)
We study superconformal interfaces between N=(1,1) supersymmetric sigma
models on tori, which preserve a u(1)^{2d} current algebra. Their fusion is
non-singular and, using parallel transport on CFT deformation space, it can be
reduced to fusion of defect lines in a single torus model. We show that the
latter is described by a semi-group extension of O(d,d;Q), and that (on the
level of Ramond charges) fusion of interfaces agrees with composition of
associated geometric integral transformations. This generalizes the well-known
fact that T-duality can be geometrically represented by Fourier-Mukai
transformations. Interestingly, we find that the topological interfaces between
torus models form the same semi-group upon fusion. We argue that this
semi-group of orbifold equivalences can be regarded as the \alpha' deformation
of the continuous O(d,d) symmetry of classical supergravity.Comment: 71 pages, 1 figure, minor additions and correction
A Decadence Baedeker: D'Annunzio's The Triumph of Death
This article investigates how Gabriele DâAnnunzioâs The Triumph of Death brings together Nietzscheâs ideas and Wagnerâs music and interweaves them with the motifs of literary Decadence and the authorâs own particular sexual politics. The novel is an experimental text striving to be a Gesemtkunstswerk, an integrated work that incorporates music, painting, poetry, regional folklore, and private thoughts about personal and national power. I discuss the novelâs themes of violent sexuality and the anxiety of powerlessness and explore their implications for the fascist political aesthetics in which DâAnnunzio played a pioneering role
A D-moduli problem?
We point out a generic problem in string-inspired supergravity models with an
anomalous . A large number of matter multiplets charged under
remain massless above the supersymmetry-breaking scale because of degeneracy of
vacua solving the D-flatness conditions. A toy model is analyzed as an
illustration of the mechanism; we find the surprising result that many scalars
remain massless after supersymmetry-breaking in a hidden sector.Comment: 11 pages, full postscript also available from
http://phyweb.lbl.gov/theorygroup/papers/44856.p
A lattice estimate of the g_{D^* D pi} coupling
We present the results of the first direct determination of the g_{D^* D pi}
coupling using lattice QCD. From our simulations in the quenched approximation,
we obtain g_{D^* D pi} = 18.8 +/- 2.3^{+1.1}_{-2.0} and hat(g) = 0.67 +/-
0.08^{+0.04}_{-0.06}. It is in agreement with a recent experimental result from
CLEO.Comment: Lattice2002(heavyquark), 3 pages, 3 figure
Folding a 2-D powder diffraction image into a 1-D scan: a new procedure
A new procedure aiming at folding a powder diffraction 2-D into a 1-D scan is
presented. The technique consists of three steps: tracking the beam centre by
means of a Simulated Annealing (SA) of the diffraction rings along the same
axis, detector tilt and rotation determination by a Hankel Lanczos Singular
Value Decomposition (HLSVD) and intensity integration by an adaptive binning
algorithm. The X-ray powder diffraction (XRPD) intensity profile of the
standard NIST Si 640c sample is used to test the performances. Results show the
robustness of the method and its capability of efficiently tagging the pixels
in a 2-D readout system by matching the ideal geometry of the detector to the
real beam-sample-detector frame. The whole technique turns out in a versatile
and user-friendly tool for the scanning of 2-D XRPD profiles.Comment: 11 pages, 1 table, 2 figure
Multiple D-branes as a D-brane
From BFSS matrix theory considerations, it is expected that a single
D-brane action can be obtained from N D-brane action in large N
limit. We examine and confirm this expectation by working out the details of
DBI and Chern-Simons terms of D-brane action from D-brane action.
We show that the same relation works for non-BPS, as well as BPS branesComment: 14 page
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