2,699 research outputs found
Vector Field Induced Chaos in Multi-dimensional Homogeneous Cosmologies
We show that in multidimensional gravity vector fields completely determine
the structure and properties of singularity. It turns out that in the presence
of a vector field the oscillatory regime exists for any number of spatial
dimensions and for all homogeneous models. We derive the Poincar\'e return map
associated to the Kasner indexes and fix the rules according to which the
Kasner vectors rotate. In correspondence to a 4-dimensional space time, the
oscillatory regime here constructed overlap the usual
Belinski-Khalatnikov-Liftshitz one.Comment: 3 pages, proceedings of the XI Marcel Grossmann meeting on
Relativistic Astrophysics, July 23-29, 2006, Berli
Liouville/Toda central charges from M5-branes
We show that the central charge of the Liouville and ADE Toda theories can be
reproduced by equivariantly integrating the anomaly eight-form of the
corresponding six-dimensional N=(0,2) theories, which describe the low-energy
dynamics of M5-branes.Comment: 9 page
On the existence of elementary abelian cycle systems
We present some necessary and/or sufficient conditions for the existence of an
elementary abelian cycle system of the complete graph.We propose a construction for some
classes of perfect elementary abelian cycle systems. Finally we consider elementary abelian
k-cycle systems of the complete multipartite graph
Finite weakly divisible nearrings
In [5] we dened and studied the algebraic structure called weakly divisible
nearring (wd-nearring). In [1, 2] a special class of finite wd-nearrings on Z_{p^n}, p
prime, was constructed: on the group (Z_{p^n}; +) of the residue classes (mod p^n)
a multiplication "*" can be dened in such a way that (Z_{p^n};+; *) becomes a
wd-nearring. Afterwards, in [3, 4] Partially Balanced Incomplete Block Designs
(PBIBDs) and codes were obtained starting from the wd-nearrings of [1, 2]
and formulae for computing their parameters could be derived just making use
of the combinatorial properties of the constructed algebraic structure.
In [9] the construction of [1, 2] was generalized to any wd-nearring. Applying
Prop. 1 of [9], in Example 2.1 of this paper a wd-nearring N = (Z_7^2
;+; *) is
constructed on the elementary abelian group (Z_7^2
; +) and a PBIBD is obtained
from N. Using the algebraic properties of N = (Z_7^2
;+; *), all the parameters of
the PBIBD are computed.
Since it seems reasonable to think the construction and the method to compute all the parameters in [3] could be extended to some additional classes of
wd-nearrings, the aim of this paper is to study in more depth the algebraic
structure of any finite wd-nearring, especially with regard to determining the
size of the elements of signicant structures in N, as partitions, normal chains
and products. In the next paragraph, the main definitions and properties of
a finite wd-nearring are recalled (Remark 2.1) and the most signicant results
presented in this paper are summarized (Remark 2.2)
Partially Balanced Incomplete Block Designs from Weakly Divisible Nearrings
In [[6] Riv. Mat. Univ. Parma 11 (2) (1970) 79–96] Ferrero demonstrates a connection between a
restricted class of planar nearrings and balanced incomplete block designs. In this paper, bearing in
mind the links between planar nearrings and weakly divisible nearrings (wd-nearrings), first we show
the construction of a family of partially balanced incomplete block designs from a special class of
wd-nearrings; consequently, we are able to give some formulas for calculating the design parameters
Tinkertoys for Gaiotto Duality
We describe a procedure for classifying N=2 superconformal theories of the
type introduced by Davide Gaiotto. Any curve, C, on which the 6D A_{N-1} SCFT
is compactified, can be decomposed into 3-punctured spheres, connected by
cylinders. We classify the spheres, and the cylinders that connect them. The
classification is carried out explicitly, up through N=5, and for several
families of SCFTs for arbitrary N. These lead to a wealth of new S-dualities
between Lagrangian and non-Lagrangian N=2 SCFTs.Comment: 61 pages, 136 figures (a veritable comic book). V2: Grotty bitmapped
figures replaced with PDF versions; a couple of references fixe
New results on path-decompositions and their down-links
In a recent paper the concept of \emph{down-link} from a
-design \cB to a -design \cB' has been
introduced. In the present paper the spectrum problems for
are studied. General results on the existence of path-decompositions
and embeddings between path-decompositions playing a fundamental role for the construction of down-links
are also presented
Reducing Interconnect Cost in NoC through Serialized Asynchronous Links
This work investigates the application of serialization as a means of reducing the number of wires in NoC combined with asynchronous links in order to simplify the clocking of the link. Throughput is reduced but savings in routing area and reduction in power could make this attractiv
Evidence of active subsidence at Basiluzzo island (Aeolian islands, southern Italy) inferred from a Roman age wharf
The Aeolian Arc (Southern Tyrrhenian Sea, Italy) is one of the most active volcanic areas of the Mediterranean
basin, affected by volcanic/hydrothermal and seismic activity. Ancient populations settled this
region since historical times, building coastal installations which currently are valuable archaeological
indicators of relative sea level changes and vertical land movements. In this study we show and discuss
data on the relative sea level change estimated from a submerged wharf of Roman age dated between 50
B.C. and 50 A.D., located at Basiluzzo Island. This structure has been studied through marine surveys and
archaeological interpretations and is presently located at a corrected depth of 4.10 0.2 m. We explain
this submergence by a cumulative effect of the relative sea level change caused by the regional glaciohydro-
isostatic signal, active since the end of the last glacial maximum, and the local volcano-tectonic
land subsidence. Finally, a total subsidence rate of 2.05 0.1 mm/yr 1, with a volcano-tectonic contribution
of 1.43 0.1 mm/yr 1 for the last 2 ka BP, is inferred from the comparison against the latest
predicted sea level curve for the Southern Tyrrhenian Sea, suggesting new evaluations of the volcanotectonic
hazard for this area of the Aeolian islands
Nilpotent orbits and codimension-two defects of 6d N=(2,0) theories
We study the local properties of a class of codimension-2 defects of the 6d
N=(2,0) theories of type J=A,D,E labeled by nilpotent orbits of a Lie algebra
\mathfrak{g}, where \mathfrak{g} is determined by J and the outer-automorphism
twist around the defect. This class is a natural generalisation of the defects
of the 6d theory of type SU(N) labeled by a Young diagram with N boxes. For any
of these defects, we determine its contribution to the dimension of the Higgs
branch, to the Coulomb branch operators and their scaling dimensions, to the 4d
central charges a and c, and to the flavour central charge k.Comment: 57 pages, LaTeX2
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