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Search Results: 1 - 10 of 147402 matches for " Sean F. Everton "
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Using Mathematical Models in Decision Making Methodologies to Find Key Nodes in the Noordin Dark Network  [PDF]
William P. Fox, Sean F. Everton
American Journal of Operations Research (AJOR) , 2014, DOI: 10.4236/ajor.2014.44025
Abstract: A Dark Network is a network that cannot be accessed through tradition means. Once uncovered, to any degree, dark network analysis can be accomplished using the SNA software. The output of SNA software includes many measures and metrics. For each of these measures and metric, the output in ORA additionally provides the ability to obtain a rank ordering of the nodes in terms of these measures. We might use this information in decision making concerning best methods to disrupt or deceive a given dark network. In the Noordin Dark network, different nodes were identified as key nodes based upon the metric used. Our goal in this paper is to use methodologies to identify the key players or nodes in a Dark Network in a similar manner as we previously proposed in social networks. We apply two multi-attribute decision making methods, a hybrid AHP & TOPSIS and an average weighted ranks scheme, to analyze these outputs to find the most influential nodes as a function of the decision makers’ inputs. We compare these methods by illustration using the Noordin Dark Network with seventy-nine nodes. We discuss sensitivity analysis that is applied to the criteria weights in order to measure the change in the ranking of the nodes.
Competition and Price Dispersion in International Long Distance Calling
Sean F. Ennis
Computer Science , 2001,
Abstract: This paper examines the relationship between changes in telecommunications provider concentration on international long distance routes and changes in prices on those routes. Overall, decreased concentration is associated with significantly lower prices to consumers of long distance services. However, the relationship between concentration and price varies according to the type of long distance plan considered. For the international flagship plans frequently selected by more price-conscious consumers of international long distance, increased competition on a route is associated with lower prices. In contrast, for the basic international plans that are the default selection for consumers, increased competition on a route is actually associated with higher prices. Thus, somewhat surprisingly, price dispersion appears to increase as competition increases.
Superspace Formulation for the BRST Quantization of the Chiral Schwinger Model
Everton M. C. Abreu,Nelson R. F. Braga
Physics , 1996, DOI: 10.1142/S0217751X98000202
Abstract: It has recently been shown that the Field Antifield quantization of anomalous irreducible gauge theories with closed algebra can be represented in a BRST superspace where the quantum action at one loop order, including the Wess Zumino term, and the anomalies show up as components of the same superfield. We show here how the Chiral Schwinger model can be represented in this formulation.
A Superspace Formulation for the Master Equation
Everton M. C. Abreu,Nelson R. F. Braga
Physics , 1995, DOI: 10.1103/PhysRevD.54.4080
Abstract: It is shown that the quantum master equation of the Field Antifield quantization method at one loop order can be translated into the requirement of a superfield structure for the action. The Pauli Villars regularization is implemented in this BRST superspace and the case of anomalous gauge theories is investigated. The quantum action, including Wess Zumino terms, shows up as one of the components of a superfield that includes the BRST anomalies in the other component. The example of W2 quantum gravity is also discussed.
Axial Anomaly from the BPHZ regularized BV master equation
Everton M. C. Abreu,Nelson R. F. Braga
Physics , 1997, DOI: 10.1142/S0217751X98002031
Abstract: A BPHZ renormalized form for the master equation of the field antifiled (or BV) quantization has recently been proposed by De Jonghe, Paris and Troost. This framework was shown to be very powerful in calculating gauge anomalies. We show here that this equation can also be applied in order to calculate a global anomaly (anomalous divergence of a classically conserved Noether current), considering the case of QED. This way, the fundamental result about the anomalous contribution to the Axial Ward identity in standard QED (where there is no gauge anomaly) is reproduced in this BPHZ regularized BV framework.
Fractional Dirac Bracket and Quantization for Constrained Systems
Everton M. C. Abreu,Cresus F. L. Godinho
Physics , 2011, DOI: 10.1103/PhysRevE.84.026608
Abstract: So far, it is not well known how to deal with dissipative systems. There are many paths of investigation in the literature and none of them present a systematic and general procedure to tackle the problem. On the other hand, it is well known that the fractional formalism is a powerful alternative when treating dissipative problems. In this paper we propose a detailed way of attacking the issue using fractional calculus to construct an extension of the Dirac brackets in order to carry out the quantization of nonconservative theories through the standard canonical way. We believe that using the extended Dirac bracket definition it will be possible to analyze more deeply gauge theories starting with second-class systems.
Somatic Genetics Empowers the Mouse for Modeling and Interrogating Developmental and Disease Processes
Sean F. Landrette,Tian Xu
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1002110
Abstract: With recent advances in genomic technologies, candidate human disease genes are being mapped at an accelerated pace. There is a clear need to move forward with genetic tools that can efficiently validate these mutations in vivo. Murine somatic mutagenesis is evolving to fulfill these needs with tools such as somatic transgenesis, humanized rodents, and forward genetics. By combining these resources one is not only able to model disease for in vivo verification, but also to screen for mutations and pathways integral to disease progression and therapeutic intervention. In this review, we briefly outline the current advances in somatic mutagenesis and discuss how these new tools, especially the piggyBac transposon system, can be applied to decipher human biology and disease.
Effects of decision-making on the transport costs across complex networks
Sean Gourley,Neil F. Johnson
Physics , 2006, DOI: 10.1016/j.physa.2006.01.050
Abstract: We analyze the effects of agents' decisions on the creation of congestion on a centralized network with ring-and-hub topology. We show that there are two classes of agents each displaying a distinct set of behaviours. The dynamics of the system are driven by an interplay between the formation of, and transition between, unique stable states that arise as the network is varied. We show how the flow of objects across the network can be understood in terms of the ordering and allocation of strategies. Our results show that the existence of congestion in a network is a dynamic process that is as much dependent on the agents' decisions as it is on the structure of the network itself.
N-Hexane Isomerization on Ni-Pt/Catalysts Supported on Mordenite  [PDF]
Geovana S. V. Martins, Everton R. F. dos Santos, Meiry G. F. Rodrigues, Gina Pecchi, Carlos M. N. Yoshioka, Dilson Cardoso
Modern Research in Catalysis (MRC) , 2013, DOI: 10.4236/mrc.2013.24017
Abstract:

The aim of this work was to evaluate the catalytic properties for n-hexane isomerization of bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HMOR zeolite as support. The method used for metal dispersion in the zeolite was competitive ion exchange using ammine complexes [Ni(NH3)6]Cl2 and [Pt(NH3)4]Cl2 as precursors. The catalysts were characterized by X-Ray diffraction, X-Ray energy dispersion spectroscopy, temperature-programmed reduction and transmission electron microscopy. The n-hexane isomerization reaction using the catalysts was carried out to evaluate the catalyst activity. The reaction was carried out in a fixed bed reactor operating at 250?C, 1 atm, H2/C6 = 9 molar ratio. The profiles obtained from TPR suggest that, for bimetallic catalysts, the presence of platinum facilitates the reduction of Ni2+ cations. The bimetallic catalysts presented a higher activity in the isomerization of n-hexane when compared to the monometallic ones, as well better stability as the Pt content in the solid increases.

Canonical Transformations and Gauge Fixing in the Triplectic Quantization
Everton M. C. Abreu,Nelson R. F. Braga,Cresus F. L. Godinho
Physics , 1998, DOI: 10.1016/S0550-3213(98)00337-X
Abstract: We show that the generators of canonical transformations in the triplectic manifold must satisfy constraints that have no parallel in the usual field antifield quantization. A general form for these transformations is presented. Then we consider gauge fixing by means of canonical transformations in this Sp(2) covariant scheme, finding a relation between generators and gauge fixing functions. The existence of a wide class of solutions to this relation nicely reflects the large freedom of the gauge fixing process in the triplectic quantization. Some solutions for the generators are discussed. Our results are then illustrated by the example of Yang Mills theory.
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