10,422 research outputs found
Critical Nodes In Directed Networks
Critical nodes or "middlemen" have an essential place in both social and
economic networks when considering the flow of information and trade. This
paper extends the concept of critical nodes to directed networks. We identify
strong and weak middlemen. Node contestability is introduced as a form of
competition in networks; a duality between uncontested intermediaries and
middlemen is established. The brokerage power of middlemen is formally
expressed and a general algorithm is constructed to measure the brokerage power
of each node from the networks adjacency matrix. Augmentations of the brokerage
power measure are discussed to encapsulate relevant centrality measures. We use
these concepts to identify and measure middlemen in two empirical
socio-economic networks, the elite marriage network of Renaissance Florence and
Krackhardt's advice network.Comment: 28 pages, 6 figures, 2 table
The primitive ideals of some \'etale groupoid C*-algebras
Consider the Deaconu-Renault groupoid of an action of a finitely generated
free abelian monoid by local homeomorphisms of a locally compact Hausdorff
space. We catalogue the primitive ideals of the associated groupoid C*-algebra.
For a special class of actions we describe the Jacobson topology.Comment: 22 page
Estimating the Firm's Labor Supply Curve in a "New Monopsony" Framework: School Teachers in Missouri
In the context of certain dynamic models, it is possible to infer the elasticity of labor supply to the firm from the elasticity of the quit rate with respect to the wage. Using this property, we estimate the average labor supply elasticity to public school districts in Missouri. We take advantage of the plausibly exogenous variation in pre-negotiated district salary schedules to instrument for actual salary. Instrumental variables estimates lead to a labor supply elasticity estimate of about 3.7, suggesting the presence of significant market power for school districts, especially over more experienced teachers. The presence of monopsony power in this labor market may be partially explained by institutional features of the teacher labor market.labor monopsony, teachers
Application of projection algorithms to differential equations: boundary value problems
The Douglas-Rachford method has been employed successfully to solve many
kinds of non-convex feasibility problems. In particular, recent research has
shown surprising stability for the method when it is applied to finding the
intersections of hypersurfaces. Motivated by these discoveries, we reformulate
a second order boundary valued problem (BVP) as a feasibility problem where the
sets are hypersurfaces. We show that such a problem may always be reformulated
as a feasibility problem on no more than three sets and is well-suited to
parallelization. We explore the stability of the method by applying it to
several examples of BVPs, including cases where the traditional Newton's method
fails
The Dixmier-Douady Classes of Certain Groupoid -Algebras with Continuous Trace
Given a locally compact abelian group , we give an explicit formula for
the Dixmier--Douady invariant of the -algebra of the groupoid extension
associated to a \v{C}ech -cocycle in the sheaf of germs of continuous
-valued functions. We then exploit the blow-up construction for groupoids to
extend this to some more general central extensions of \'etale equivalence
relations
Energy innovation in Latin America: R&D effort, deployment, and capability accumulation
Ibero-America, just as the rest of the world, faces an increasing urgency to transform existing energy systems. In the past, incentives to develop energy systems were induced mainly by changes in demand (derived from industrialization and urbanization) and by price shocks in fuels. Diversification of energy sources followed a growing need of use of particular energy forms. For developing countries, innovating in energy systems meant fundamentally gaining control over natural resources and moving away from primary, export-oriented enclaves into industrial integration, as well as improving energy security. Today, however, environmental constraints and the pressing need to reduce energy poverty forge additional challenges and set new directions to change the ways in which we use and produce energy. Improving current technologies along the same trajectory is simply not enough. Fundamental changes must take place in our economic systems in order to combine energy efficiency with low-carbon, sustainable energy sources, for which new abilities and solutions need to be targeted.energy innovation; Latin America
- …