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70
Predicting symmetric spherical shell assemblies
, 2014
"... We characterize tiled, symmetric shell structures and address the computational problem of predicting the assembly of 3D spherical shell structures from primitive 3D building blocks (or primitive tiles). We provide an efficient polynomial time, shell assembly approximation solution (based on a combi ..."
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We characterize tiled, symmetric shell structures and address the computational problem of predicting the assembly of 3D spherical shell structures from primitive 3D building blocks (or primitive tiles). We provide an efficient polynomial time, shell assembly approximation solution (based on a
Analysis of grid imprinting on geodesic spherical icosahedral grids
"... Numerical grid imprinting errors have often been observed in global atmospheric models on icosahedral grids. In this paper we analyse the sources of grid imprinting error related to the usual finite volume discretization of the divergence operator. We introduce the concept of alignment of computatio ..."
STRUCTURES
, 2011
"... Approval of the thesis: DESIGN METHODS FOR PLANAR AND SPATIAL DEPLOYABLE ..."
Inflationary trispectrum from graviton exchange
"... Abstract. We compute the connected fourpoint correlation function of the primordial curvature perturbation generated during inflation with standard kinetic terms, where the correlation is established via exchange of a graviton between two pairs of scalar fluctuations. Any such correlation yields a ..."
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Cited by 40 (6 self)
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Abstract. We compute the connected fourpoint correlation function of the primordial curvature perturbation generated during inflation with standard kinetic terms, where the correlation is established via exchange of a graviton between two pairs of scalar fluctuations. Any such correlation yields a contribution to the scalar trispectrum of the order of the tensor to scalar ratio r. This contribution is numerically one order of magnitude larger than the one previously calculated on the basis of scalar perturbations interacting at a point and satisfies a simple relation in the limit where the momentum of the graviton which is exchanged becomes much smaller than the external momenta. We conclude that the total nonlinearity parameter generated by singlefield models of slowroll inflation is at maximum τNL  ∼ r. ‡ Permanent addressInflationary trispectrum from graviton exchange 2 1.
RELATIONAL QUADRILATERALLAND. I CONFIGURATION SPACE COORDINATES
"... Relational particle models (RPM’s) are toy models of many aspects of GR in geometrodynamical form. They are suitable as toy models for studying 1) strategies for the problem of time in quantum gravity, in particular timeless, semiclassical, histories and observables approaches and combinations of th ..."
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, and triangle area, which is also a democracy invariant), B) subsystemsplit parabolic coordinates and C) the most blockwisesimple coordinates (spherical polars). These were key to unlocking the dynamics, QM and problem of time calculations for the triangle, and their counterparts turn out to be likewise
CONFORMAL TILINGS I: FOUNDATIONS, THEORY, AND PRACTICE
"... Abstract. This paper opens a new chapter in the study of planar tilings by introducing conformal tilings. These are similar to traditional tilings in that they realize abstract patterns of combinatorial polygons as concrete patterns of geometric shapes, the tiles. In the conformal case, however, th ..."
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Abstract. This paper opens a new chapter in the study of planar tilings by introducing conformal tilings. These are similar to traditional tilings in that they realize abstract patterns of combinatorial polygons as concrete patterns of geometric shapes, the tiles. In the conformal case, however
GAUSS IMAGES OF HYPERBOLIC CUSPS WITH CONVEX POLYHEDRAL BOUNDARY
, 2009
"... We prove that a 3–dimensional hyperbolic cusp with convex polyhedral boundary is uniquely determined by its Gauss image. Furthermore, any spherical metric on the torus with cone singularities of negative curvature and all closed contractible geodesics of length greater than 2π is the metric of the ..."
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Cited by 2 (1 self)
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We prove that a 3–dimensional hyperbolic cusp with convex polyhedral boundary is uniquely determined by its Gauss image. Furthermore, any spherical metric on the torus with cone singularities of negative curvature and all closed contractible geodesics of length greater than 2π is the metric
qbio.BM/0510028
, 2005
"... Classification of capped tubular viral particles in the family of Papovaviridae ..."
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Classification of capped tubular viral particles in the family of Papovaviridae
Quantizing Using Lattice Intersections
 Journal of Discrete and Computational Geometry
, 2002
"... The usual quantizer based on an ndimensional lattice # maps a point x # R n to a closest lattice point. Suppose # is the intersection of lattices # 1 , . . . , # r . Then one may instead combine the information obtained by simultaneously quantizing x with respect to each of the # i . This corre ..."
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Cited by 7 (2 self)
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The usual quantizer based on an ndimensional lattice # maps a point x # R n to a closest lattice point. Suppose # is the intersection of lattices # 1 , . . . , # r . Then one may instead combine the information obtained by simultaneously quantizing x with respect to each of the # i . This corresponds to decomposing R n into a honeycomb of cells which are the intersections of the Voronoi cells for the # i , and identifying the cell to which x belongs. This paper shows how to write several standard lattices (the facecentered and bodycentered cubic lattices, the root lattices D 4 , E # 6 , E 8 , the CoxeterTodd, BarnesWall and Leech lattices, etc.) in a canonical way as intersections of a small number of simpler, decomposable, lattices. The cells of the honeycombs are given explicitly and the mean squared quantizing error calculated in the cases when the intersection lattice is the facecentered or bodycentered cubic lattice or the lattice D 4 . 1.
Results 1  10
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70