9,305 research outputs found
The Efficiency and Evolution of R&D Networks
This work introduces a new model to investigate the efficiency and evolution of networks of firms exchanging knowledge in R&D partnerships. We first examine the efficiency of a given network structure in terms of the maximization of total profits in the industry. We show that the efficient network structure depends on the marginal cost of collaboration. When the marginal cost is low, the complete graph is efficient. However, a high marginal cost implies that the efficient network is sparser and has a core-periphery structure. Next, we examine the evolution of the network struc- ture when the decision on collaborating partners is decentralized. We show the existence of mul- tiple equilibrium structures which are in general inefficient. This is due to (i) the path dependent character of the partner selection process, (ii) the presence of knowledge externalities and (iii) the presence of severance costs involved in link deletion. Finally, we study the properties of the emerg- ing equilibrium networks and we show that they are coherent with the stylized facts of R&D net- works.R&D networks, technology spillovers, network efficiency, network formation
Strong Interactions at Low Energy
The lectures review some of the basic concepts relevant for an understanding
of the low energy properties of the strong interactions: chiral symmetry,
spontaneous symmetry breakdown, Goldstone bosons, quark condensate. The
effective field theory used to analyze the low energy structure is briefly
sketched. As an illustration, I discuss the implications of the recent data on
the decay for the magnitude of the quark condensate.Comment: Lectures given at the school of physics "Understanding the structure
of hadrons", Prague, July 2001, 20 p
Muonium-Antimuonium Oscillations in an extended Minimal Supersymmetric Standard Model with right-handed neutrinos
The electron and muon number violating muonium-antimuonium oscillation
process in an extended Minimal Supersymmetric Standard Model is investigated.
The Minimal Supersymmetric Standard Model is modified by the inclusion of three
right-handed neutrino superfields. While the model allows the neutrino mass
terms to mix among the different generations, the sneutrino and slepton mass
terms have only intra-generation lepton number violation but not
inter-generation lepton number mixing. So doing, the muonium-antimuonium
conversion can then be used to constrain those model parameters which avoid
further constraint from the decay bounds. For a wide range of
parameter values, the contributions to the muonium-antimuonium oscillation time
scale are at least two orders of magnitude below the sensivity of current
experiments. However, if the ratio of the two Higgs field VEVs, , is
very small, there is a limited possibility that the contributions are large
enough for the present experimental limit to provide an inequality relating
with the light neutrino mass scale which is generated by
see-saw mechanism. The resultant lower bound on as a function of
is more stringent than the analogous bounds arising from the muon and
electron anomalous magnetic moments as computed using this model.Comment: 29 pages, 7 figures, 3 tables, Late
Independent coalition in graphs
An independent coalition in a graph consists of two disjoint sets
of vertices and , neither of which is an independent dominating set
but whose union is an independent dominating set. An independent
coalition partition in a graph is a vertex partition such that each set of either is an
independent dominating set consisting of a single vertex of degree , or is
not an independent dominating set but forms an independent coalition with
another set which is not an independent dominating set. In this
paper we study the concept of independent coalition partition (ic-partition).
We introduce a family of graphs that have no ic-partition. We also determine
the independent coalition number of some custom graphs and investigate graphs
with and the trees with , where
denotes the order of the graph.Comment: 17 page
Grundy dominating sequences on X-join product
In this paper we study the Grundy domination number on the X-join product Gā©R of a graph G and a family of graphs R={Gv:vāV(G)}. The results led us to extend the few known families of graphs where this parameter can be efficiently computed. We prove that if, for all vāV(G), the Grundy domination number of Gv is given, and G is a power of a cycle, a power of a path, or a split graph, computing the Grundy domination number of Gā©R can be done in polynomial time. In particular, our results for powers of cycles and paths are derived from a polynomial reduction to the Maximum Weight Independent Set problem on these graphs. As a consequence, we derive closed formulas to compute the Grundy domination number of the lexicographic product GāH when G is a power of a cycle, a power of a path or a split graph, generalizing the results on cycles and paths given by BreÅ”ar et al. in 2016. Moreover, our results on the X-join product when G is a split graph also provide polynomial-time algorithms to compute the Grundy domination number for (q,qā4) graphs, partner limited graphs and extended P4-laden graphs, graph classes that are high in the hierarchy of few P4ās graphs.Fil: Nasini, Graciela Leonor. Consejo Nacional de Investigaciones CientĆficas y TĆ©cnicas. Centro CientĆfico TecnolĆ³gico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas IngenierĆa y Agrimensura. Escuela de Ciencias Exactas y Naturales. Departamento de MatemĆ”tica; ArgentinaFil: Torres, Pablo. Consejo Nacional de Investigaciones CientĆficas y TĆ©cnicas. Centro CientĆfico TecnolĆ³gico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas IngenierĆa y Agrimensura. Escuela de Ciencias Exactas y Naturales. Departamento de MatemĆ”tica; Argentin
Well Performance Tracking in a Mature Waterflood Asset
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