47 research outputs found
Some new Menon designs with parameters (196,91,42)
There are exactly 54 symmetric (196,91,42) designs admitting an
automorphism group isomorphic to acting with orbit size distribution (1,13,13,13,39,39,39,39) for
blocks and points. For 50 of these designs the full automorphism group
has order 234 and is isomorphic to .
The remaining four designs have as a full automorphism group.Among these designs there are 18 self-dual designs and 18 pairs of mutually dual ones.
The derived designs (with respect to the fixed block) of the four designs with a full automorphism group of order 1638 are cyclic
On path graphs of incidence graphs
For a given graph and a positive integer the -path graph has for vertices the set of paths of length in .
Two vertices are connected in when the intersection of the
corresponding paths forms a path of length in , and their union forms either a cycle or a path of length . Path graphs were proposed as a generalization of line graphs.
In this article we investigate some properties of path graphs of bipartite graphs, especially path graphs of incidence graphs of configurations
Unique symmetric (66,26,10) design admitting an automorphism of order 55
We have proved that the first known symmetric (66,26,10) design, constructed by Tran van Trung, is up to isomorphism the only symmetric (66,26,10) design admitting an automorphism
of order 55. A full automorphism group of that design is isomorphic to
Frob_{55}times D_{10}
A class of Siamese twin Menon designs
A{0,±1}-matrix S is called a Siamese twin design
sharing the entries of I, if S = I + K − L, where I, K, L are non-zero
{0, 1}-matrices and both I + K and I + L are incidence matrices of
symmetric designs with the same parameters. Let p and 2p−1 be prime powers and p ≡ 3 (mod 4). We describe a construction of a Siamese twin Menon design with parameters (4p², 2p² −p, p² −p), yielding a Siamese twin Hadamard design with parameters (4p ²− 1, 2p ²− 1, p² − 1)
BF Actions for the Husain-Kuchar Model
We show that the Husain-Kuchar model can be described in the framework of BF
theories. This is a first step towards its quantization by standard
perturbative QFT techniques or the spin-foam formalism introduced in the
space-time description of General Relativity and other diff-invariant theories.
The actions that we will consider are similar to the ones describing the
BF-Yang-Mills model and some mass generating mechanisms for gauge fields. We
will also discuss the role of diffeomorphisms in the new formulations that we
propose.Comment: 21 pages (in DIN A4 format), minor typos corrected; to appear in
Phys. Rev.
The Solution Space of the Unitary Matrix Model String Equation and the Sato Grassmannian
The space of all solutions to the string equation of the symmetric unitary
one-matrix model is determined. It is shown that the string equation is
equivalent to simple conditions on points and in the big cell \Gr
of the Sato Grassmannian . This is a consequence of a well-defined
continuum limit in which the string equation has the simple form \lb \cp
,\cq_- \rb =\hbox{\rm 1}, with \cp and \cq_- matrices of
differential operators. These conditions on and yield a simple
system of first order differential equations whose analysis determines the
space of all solutions to the string equation. This geometric formulation leads
directly to the Virasoro constraints \L_n\,(n\geq 0), where \L_n annihilate
the two modified-KdV \t-functions whose product gives the partition function
of the Unitary Matrix Model.Comment: 21 page
Minisuperspace Quantization of "Bubbling AdS" and Free Fermion Droplets
We quantize the space of 1/2 BPS configurations of Type IIB SUGRA found by
Lin, Lunin and Maldacena (hep-th/0409174), directly in supergravity. We use the
Crnkovic-Witten-Zuckerman covariant quantization method to write down the
expression for the symplectic structure on this entire space of solutions. We
find the symplectic form explicitly around AdS_5 x S^5 and obtain a U(1)
Kac-Moody algebra, in precise agreement with the quantization of a system of N
free fermions in a harmonic oscillator potential, as expected from AdS/CFT. As
a cross check, we also perform the quantization around AdS_5 x S^5 by another
method, using the known spectrum of physical perturbations around this
background and find precise agreement with our previous calculation.Comment: 22 Pages + 2 Appendices, JHEP3; v3: explanation of factor 2 mismatch
added, references reordered, published versio
Expression of inhibitor of apoptosis protein Livin in renal cell carcinoma and non-tumorous adult kidney
The antiapoptotic Livin/ML-IAP gene has recently gained much attention as a potential new target for cancer therapy. Reports indicating that livin is expressed almost exclusively in tumours, but not in the corresponding normal tissue, suggested that the targeted inhibition of livin may present a novel tumour-specific therapeutic strategy. Here, we compared the expression of livin in renal cell carcinoma and in non-tumorous adult kidney tissue by quantitative real-time reverse transcription-PCR, immunoblotting, and immunohistochemistry. We found that livin expression was significantly increased in tumours (P=0.0077), but was also clearly detectable in non-tumorous adult kidney. Transcripts encoding Livin isoforms α and β were found in both renal cell carcinoma and normal tissue, without obvious qualitative differences. Livin protein in renal cell carcinoma samples exhibited cytoplasmic and/or nuclear staining. In non-tumorous kidney tissue, Livin protein expression was only detectable in specific cell types and restricted to the cytoplasm. Thus, whereas the relative overexpression of livin in renal cell carcinoma indicates that it may still represent a therapeutic target to increase the apoptotic sensitivity of kidney cancer cells, this strategy is likely to be not tumour-specific
Background-Independence
Intuitively speaking, a classical field theory is background-independent if
the structure required to make sense of its equations is itself subject to
dynamical evolution, rather than being imposed ab initio. The aim of this paper
is to provide an explication of this intuitive notion. Background-independence
is not a not formal property of theories: the question whether a theory is
background-independent depends upon how the theory is interpreted. Under the
approach proposed here, a theory is fully background-independent relative to an
interpretation if each physical possibility corresponds to a distinct spacetime
geometry; and it falls short of full background-independence to the extent that
this condition fails.Comment: Forthcoming in General Relativity and Gravitatio