261 research outputs found

    Differential Regularization of Topologically Massive Yang-Mills Theory and Chern-Simons Theory

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    We apply differential renormalization method to the study of three-dimensional topologically massive Yang-Mills and Chern-Simons theories. The method is especially suitable for such theories as it avoids the need for dimensional continuation of three-dimensional antisymmetric tensor and the Feynman rules for three-dimensional theories in coordinate space are relatively simple. The calculus involved is still lengthy but not as difficult as other existing methods of calculation. We compute one-loop propagators and vertices and derive the one-loop local effective action for topologically massive Yang-Mills theory. We then consider Chern-Simons field theory as the large mass limit of topologically massive Yang-Mills theory and show that this leads to the famous shift in the parameter kk. Some useful formulas for the calculus of differential renormalization of three-dimensional field theories are given in an Appendix.Comment: 25 pages, 4 figures. Several typewritten errors and inappropriate arguments are corrected, especially the correct adresses of authors are give

    Synergy of DNA intercalation and catalytic activity of a copper complex towards improved polymerase inhibition and cancer cell cytotoxicity

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    Improving the binding of metal complexes to DNA to boost cancer cell cytotoxicity requires fine tuning of their structural and chemical properties. Copper has been used as a metal center in compounds containing intercalating ligands due to its ability to catalytically generate reactive oxygen species (ROS), such as hydroxyl radicals (OH˙). We envision the synergy of DNA binding and ROS generation in proximity to target DNA as a powerful chemotherapy treatment. Here, we explore the use of [Cu(2CP-Bz-SMe)]2+(2CP-Bz-SMe = 1,3-bis(1,10-phenanthrolin-2-yloxy)-N-(4-(methylthio)benzylidene)propan-2-amine) for this purpose by characterizing its cytotoxicity, DNA binding, and ability to affect DNA replication through the polymerase chain reaction - PCR and nuclease assays. We determined the binding (Kb) and Stern-Volmer constants (KSV) for complex-DNA association of 5.8 ± 0.14 × 104and 1.64 (±0.08), respectively, through absorption titration and competitive fluorescence experiments. These values were superior to those of other Cu-complex intercalators. We hypothesize that the distorted trigonal bipyramidal geometry of [Cu(2CP-Bz-SMe)]2+allows the phenanthroline fragments to be better accommodated into the DNA double helix. Moreover, the aromaticity of these fragments increases the local hydrophobicity thus increasing the affinity for the hydrophobic domains of DNA. Nuclease assays in the presence of common reducing agents ascorbic acid, nicotinamide adenine dinucleotide, and glutathione showed the effective degradation of DNA due to thein situgeneration of OH˙. The [Cu(2CP-Bz-SMe)]2+complex showed cytotoxicity against the following human cancer cells lines A549, MCF-7, MDA-MB-231 and MG-63 with half maximal inhibitory concentration (IC50) values of 4.62 ± 0.48, 5.20 ± 0.76, 5.70 ± 0.42 and 2.88 ± 0.66 μM, respectively. These low values of IC50, which are promising if compared to that of cisplatin, are ascribed to the synergistic effect of ROS generation with the intercalation ability into the DNA minor grooves and blocking DNA replication. This study introduces new principles for synergizing the chemical and structural properties of intercalation compounds for improved drug-DNA interactions targeting cancer.Fil: Romo, Adolfo I. B.. University of Illinois. Urbana - Champaign; Estados Unidos. Universidade Federal do Ceara; BrasilFil: Carepo, Marta P.. Universidade Nova de Lisboa; PortugalFil: Levin, Pedro. Universidad de Santiago de Chile; ChileFil: Nascimento, Otaciro R.. Universidade Federal do São Carlos; BrasilFil: Díaz, Daniel E.. Universidad de Santiago de Chile; ChileFil: Rodriguez Lopez, Joaquin. University of Illinois. Urbana - Champaign; Estados UnidosFil: Leon, Ignacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Bezerra, Lucas F.. Universidade Federal do Ceara; BrasilFil: Lemus, Luis A.. Universidad de Santiago de Chile; ChileFil: Diógenes, Izaura C. N.. Universidade Federal do Ceara; Brasi

    Hysterothylacium larvae (Nematoda, Anisakidae) in the freshwater mussel Diplodon suavidicus (Lea, 1856) (Mollusca, Unioniformes, Hyriidae) in Aripuanã River, Amazon, Brazil

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    Larvae of Hysterothylacium use various invertebrates as intermediate hosts. Definite hosts include fish, birds, reptiles or marine mammals. This study describes the occurrence of Hysterothylacium (Nematoda, Anisakidae) larvae parasitizing the pericardic cavity of Diplodon suavidicus (Unioniformes, Hyriidae) specimens collected in the Amazon basin, Brazil. This is the first record of this nematode parasitizing freshwater bivalves in South America. The high prevalence, medium intensity and medium abundance suggest that D. suavidicus acts as intermediate host for Hysterothylacium species in that environment. © 2010 Elsevier Inc

    Markov Chain methods for the Bipartite Boolean Quadratic Programming Problem

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    We study the Bipartite Boolean Quadratic Programming Problem (BBQP) which is an extension of the well known Boolean Quadratic Programming Problem (BQP). Applications of the BBQP include mining discrete patterns from binary data, approximating matrices by rank-one binary matrices, computing the cut-norm of a matrix, and solving optimisation problems such as maximum weight biclique, bipartite maximum weight cut, maximum weight induced sub-graph of a bipartite graph, etc. For the BBQP, we first present several algorithmic components, specifically, hill climbers and mutations, and then show how to com- bine them in a high-performance metaheuristic. Instead of hand-tuning a standard metaheuristic to test the efficiency of the hybrid of the components, we chose to use an automated generation of a multi- component metaheuristic to save human time, and also improve objectivity in the analysis and compar- isons of components. For this we designed a new metaheuristic schema which we call Conditional Markov Chain Search (CMCS). We show that CMCS is flexible enough to model several standard metaheuristics; this flexibility is controlled by multiple numeric parameters, and so is convenient for automated genera- tion. We study the configurations revealed by our approach and show that the best of them outperforms the previous state-of-the-art BBQP algorithm by several orders of magnitude. In our experiments we use benchmark instances introduced in the preliminary version of this paper and described here, which have already become the de facto standard in the BBQP literature

    Optical Coherence Tomography and Fibrous Cap Characterization

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    The pathophysiology of acute coronary syndromes has long been associated with atherosclerotic plaque rupture. Inflammation, thinning, and disruption of the fibrous cap have been implicated with the final processes leading to plaque rupture, but confirmation of these mechanisms of coronary thrombosis in humans has been hampered by the lack of imaging methods with sufficient resolution to resolve fibrous cap characterization and thickness in vivo. Intravascular optical coherence tomography (OCT) provides images with micron-level axial and lateral resolution, enabling detailed visualization of micro-structural changes of the arterial wall. The present article provides an overview of the potential role of OCT in identifying and characterizing fibrous cap morphology, thickness, and inflammation in human coronary plaques
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