3,472 research outputs found
On the cubicity of certain graphs
No full textThe boxicity of a graph G is the minimum dimension b such that G is representable as the intersection graph of axis-parallel boxes in the b-dimensional space. When the boxes are restricted to be axis-parallel b-dimensional cubes, the minimum dimension b required to represent G is called the cubicity of G. In this paper we show that cubicity(H-d) <=, 2d, where Hd is the d-dimensional hypercube. (The d-dimensional hypercube is the graph on 2d vertices which corresponds to the 2(d) d-vectors whose components are either 0 or 1, two of the vertices being adjacent when they differ in just one coordinate.) We also show that cubicity(H-d) >= (d - 1)/(log d). We also show that (1) cubicity(G) >= (log alpha)/(log(D + 1)), (2) cubicity(G) >= (log n - log omega)/(log D), where alpha, omega, D and n denote the stability number, the clique number, the diameter and the number of vertices of G. As consequences of these lower bounds we provide lower bounds for the cubicity of planar graphs, bipartite graphs, triangle-free graphs, etc., in terms of their diameter and the number of vertices. (c) 2005 Elsevier B.V. All rights reserved
The stable set problem and the thinness of a graph
No full textWe introduce a poly-time algorithm for the maximum weighted stable set problem, when a certain representation is given for a graph. The algorithm generalizes the algorithm for interval graphs and that for graphs with bounded pathwidth. By a suitable application to the frequency assignment problem, we improved several solutions to relevant benchmark instances. (c) 2006 Elsevier B.V. All rights reserved
NFAT and CREB Regulate Kaposi's Sarcoma-Associated Herpesvirus-Induced Cyclooxygenase 2 (COX-2)
No full textABSTRACT
COX-2 has been implicated in Kaposi's sarcoma-associated herpesvirus (KSHV) latency and pathogenesis (A. George Paul, N. Sharma-Walia, N. Kerur, C. White, and B. Chandran, Cancer Res. 70:3697-3708, 2010; P. P. Naranatt, H. H. Krishnan, S. R. Svojanovsky, C. Bloomer, S. Mathur, and B. Chandran, Cancer Res. 64:72-84, 2004; N. Sharma-Walia, A. G. Paul, V. Bottero, S. Sadagopan, M. V. Veettil, N. Kerur, and B. Chandran, PLoS Pathog. 6:e1000777, 2010; N. Sharma-Walia, H. Raghu, S. Sadagopan, R. Sivakumar, M. V. Veettil, P. P. Naranatt, M. M. Smith, and B. Chandran, J. Virol. 80:6534-6552, 2006). However, the precise regulatory mechanisms involved in COX-2 induction during KSHV infection have never been explored. Here, we identified
cis
-acting elements involved in the transcriptional regulation of COX-2 upon KSHV
de
novo
infection. Promoter analysis using human COX-2 promoter deletion and mutation reporter constructs revealed that nuclear factor of activated T cells (NFAT) and the cyclic AMP (cAMP) response element (CRE) modulate KSHV-mediated transcriptional regulation of COX-2. Along with multiple KSHV-induced signaling pathways, infection-induced prostaglandin E
2
(PGE
2
) also augmented COX-2 transcription. Infection of endothelial cells markedly induced COX-2 expression via a cyclosporine A-sensitive, calcineurin/NFAT-dependent pathway. KSHV infection increased intracellular cAMP levels and activated protein kinase A (PKA), which phosphorylated the CRE-binding protein (CREB) at serine 133, which probably led to interaction with CRE in the COX-2 promoter, thereby enhancing COX-2 transcription. PKA selective inhibitor H-89 pretreatment strongly inhibited CREB serine 133, indicating the involvement of a cAMP-PKA-CREB-CRE loop in COX-2 transcriptional regulation. In contrast to phosphatidylinositol 3-kinase and protein kinase C, inhibition of FAK and Src effectively reduced KSHV infection-induced COX-2 transcription and protein levels. Collectively, our study indicates that mediation of COX-2 transcription upon KSHV infection is a paradigm of a complex regulatory milieu involving the interplay of multiple signal cascades and transcription factors. Intervention at each step of COX-2/PGE
2
induction can be used as a potential therapeutic target to treat KSHV-associated neoplasm and control inflammatory sequels of KSHV infection.
</jats:p
Horizon entanglement area law from regular black hole thermodynamics
No full textWe investigate the thermodynamics of regular black hole configurations via quantum analogs of entropy
and energy—namely, the entanglement entropy and entanglement energy—near the event horizon of
Bardeen and Hayward black holes. Following standard approaches, we introduce a quantum scalar field
propagating in such black hole spacetimes and discretize the field degrees of freedom on a lattice of
spherical shells.We observe that, at leading order, the entanglement entropy associated with the scalar field
is proportional to Bekenstein-Hawking entropy, while the corresponding entanglement energy scales
proportionally to Komar energy.We then compute the heat capacity in both scenarios, discussing the black
hole stability conditions and the possible appearance of second-order phase transitions. Finally, we extend
our analysis to the black hole core, showing that in this sector entanglement energy serves as a valuable tool
towards discriminating between singular and regular solutions
C.-H. Abesamis, D.-S. Amalorpavadass, J.-R. Chandran et a., Théologies du Tiers-Monde. Du conformisme à l'indépendance. Le Colloque de Dar-es-Salaam et ses prolongements. 1977
No full textThils Gustave. C.-H. Abesamis, D.-S. Amalorpavadass, J.-R. Chandran et a., Théologies du Tiers-Monde. Du conformisme à l'indépendance. Le Colloque de Dar-es-Salaam et ses prolongements. 1977. In: Revue théologique de Louvain, 9ᵉ année, fasc. 2, 1978. pp. 207-212
C.-H. Abesamis, D.-S. Amalorpavadass, J.-R. Chandran et a., Théologies du Tiers-Monde. Du conformisme à l'indépendance. Le Colloque de Dar-es-Salaam et ses prolongements. 1977
No full textThils Gustave. C.-H. Abesamis, D.-S. Amalorpavadass, J.-R. Chandran et a., Théologies du Tiers-Monde. Du conformisme à l'indépendance. Le Colloque de Dar-es-Salaam et ses prolongements. 1977. In: Revue théologique de Louvain, 9ᵉ année, fasc. 2, 1978. pp. 207-212
A modified peridynamic method to model the fracture behaviour of nanocomposites
No full textIn the present work, a numerical investigation based on a modified peridynamic method of fracture properties of epoxy resin reinforced by nanoparticles, more specifically hyperbranched polyester (HBP), was conducted. Due to the specific features of HBP, certain material nodes in the numerical model were constrained to accurately replicate the effect of HBP in pure epoxy resin, and a Monte Carlo method was used to simulate the random distribution of HBP. The numerical model was validated by fracture tests with single-edge-notched bending (SENB) samples. Moreover, the effect of the HBP weight fraction on the fracture properties was analysed. With increaseing HBP weight fraction, a three-stage increase of mode-I fracture toughness in a rapid-slow-rapid manner was obtained. Overall, the proposed modified peridynamic method provided a macroscale analysis of the fracture behaviour of nanocomposites reinforced by HBP in a simulation framework
On monophonic position sets in graphs
No full textThe general position problem in graph theory asks for the largest set S of vertices of a graph G such that no shortest path of G contains more than two vertices of S. In this paper we consider a variant of the general position problem called the monophonic position problem, obtained by replacing 'shortest path' by 'induced path'. We prove some basic properties and bounds for the monophonic position number of a graph and determine the monophonic position number of some graph families, including unicyclic graphs, complements of bipartite graphs and split graphs. We show that the monophonic position number of triangle -free graphs is bounded above by the independence number. We present realisation results for the general position number, monophonic position number and monophonic hull number. Finally we discuss the complexity of the monophonic position problem. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
ON THE VERTEX POSITION NUMBER OF GRAPHS
No full textIn this paper we generalise the notion of visibility from a point in an integer lattice to the setting of graph theory. For a vertex x of a graph G, we say that a set S subset of V (G) is an x-position set if for any y is an element of S the shortest x, y-paths in G contain no point of S \ {y}. We investigate the largest and smallest orders of maximum x-position sets in graphs, determining these numbers for common classes of graphs and giving bounds in terms of the girth, vertex degrees, diameter and radius. Finally we discuss the complexity of finding maximum vertex position sets in graphs
Human pose extraction from monocular videos using constrained non-rigid factorization
No full textWe focus on the problem of automatically extracting the 3D configuration of human poses from 2D image features tracked over a finite interval of time . This problem is highly non-linear in nature and confounds standard regression techniques. Our approach effectively marries a non-rigid factorization algorithm with prior learned statistical models from archival motion capture database. We show that a stand alone non-rigid factorization algorithm is highly unsuitable for this problem. However, when coupled with the learned statistical model in the form of a constrained non- linear programming method, it yields a substantially better solution.Appu Shaji, Behajt Siddiquie, Sharat Chandran and David Suterhttp://www.cse.iitb.ac.in/appu/publications.ph
- …
