Connectivity in the Commercial Internet

We study the 'backbone market' in the Internet. After discussing the structure of the Internet, we use an extension of the Katz-Shapiro network model to analyze the strategies that would be used by dominant backbone. We show that a larger backbone prefers a lower quality interconnection than the smaller one. We then analyze a 'targeted degradation' strategy where the larger backbone lowers the quality of interconnection to its smaller rivals in turn. Finally, we show that the qualitative results are robust to the possibility of 'multihoming' by clients.     

The Effects of a Federal Flat Tax on Agriculture

This study examines the impact of a federal flat tax on agriculture by determining the tax liability under the current and flat tax systems using actual farm records. The study considers the linkages between agriculture and the rest of the economy by examining the impact of a flat tax on interest rates and capital investment and how those changes would affect agriculture. Results indicate that roughly 63% of agricultural producers would benefit from a flat tax in terms of lowering taxes paid. Under the flat tax, larger farms and more profitable farms would be relatively better off.     

The rest of me

iPhone Siri demonstratively introduced natural language processing. Still a gadget, the idea revived one of the old promises of computers as personal assistants. Does it have the potential of fulfilling the already burgeoning imagination related to this promise? The authors believe that, while still dependent on the evolution of artificial intelligence, the virtual assistant may find support in the already maturing technologies of augmented reality and, more important, in the changing global network with the semantic web, Internet of things and geo-location. Bluntly speaking, its feasibility and acceptability may not even have to wait for the promised IBM computer with human brain capabilities, but rather build on a more friendly interaction with the Google search engine.The article provides a narrative scenario of the deep economic and social transformations and even turbulence that the so called imaginary friend may produce. Not discarding, but creatively integrating some of the archetypes of futuristic literature, the story positions these entities as the foreground of a deep integration of networks, with the added turmoil caused by economic interests that go beyond individuals’ sense-making capacity.This article is one of the follow-ups of the international foresight workshop “Crazy futures” coordinated by Ziauddin Sardar and George Cairns in a small resort on the Danube Delta in July 2011, a workshop organised as part of the project Quality and Leadership for Romanian Higher Education.     

Job mobility and the gender wage gap in Italy

This paper investigates the contribution of gender differences in job mobility to the emergence of a gender wage gap in the Italian labour market. We show that over the first 10 years of labour market experience job mobility accounts for up to 30% of total log wage growth for men and only 8.3% for women, and that this difference is mainly due to differences in returns to mobility. The gender mobility gap is robust to the inclusion of individual, job and firm characteristics, to different ways of accounting for individual unobserved heterogeneity, and is mainly found for voluntary job moves. Looking at the characteristics of the jobs and the firms' workers move to, we find that moves to larger firms represent by far the main source of gender differences in returns to mobility. We offer two possible explanations for this finding; one which involves differences in bargaining behaviour and one which relates to the theory of compensating differentials.     

Descriptive statistics of large data sets by scatter plots, an exploratory approach

In the analysis of large tables of M variables on N observations one is interested in the relations between the variables and it is usual to inspect the M(M-1)/2 scatter plots of N points. Clearly, the scatter plot approach relies on visual inspection and is to be preferred in so far as applicable to detect simple relations, namely when M is small. Other approaches are needed for large values of M .
We consider that only the relatively few scatter plots that present a 'structure' are of interest for an exploratory analysis and, by 'structure', we mean a domain of specially high local density in the plot. Based on this concept, we propose a method constructed around two steps: the selection of the possibly interesting pairs of variables and the validation of the corresponding scatter plots. The selection of the pairs results from an algorithm based on a binary partitioning tree. The validation of the corresponding scatter plots enables the production of only those where a structure is found the recognition of a structure is derived from a statistic based on the length of the Minimum Spanning Tree constructed on the N points of the candidate scatter plot.
For illustration, we report on an industrial application where the method is routinely applied for exploratory purposes.     

Increasing the usability and accessibility of geodynamic modelling tools to the geoscience community: UnderworldGUI

Geoscientists are faced with a number of complexities that represent obstacles to the development of realistic simulation of deep earth processes. Realistic 4D thermo-mechanical simulation using software packages like Underworld and Gale, when combined appropriately with geoscientific expertise, can lead to novel insights into the deformation of geological structures at a wide range of time and spatial scales. The challenge for end-user geoscientists lies in applying their knowledge within the framework of the software’s input specification, including initial, internal, and boundary conditions and output visualization parameters. We have built a Graphical User Interface (GUI) to remove many of the difficulties related to editing the Extensible Markup Language (XML) encoded input files of Underworld/Gale geomodels and therefore, to greatly broaden the user base of these software packages. By helping Underworld/Gale to meet a large audience, we provide a tool to the geoscience community that helps to move from untested conceptual models to physically valid, properly scaled modelling. Furthermore, the UnderworldGUI offers a mechanism for storing and retrieving experimental models in a centralised database, thus providing the geoscience community with a means to share the outcomes of its experimental research. Further details of the UnderworldGUI are available at the web site http://www.wiki.vislab.usyd.edu.au/moinwiki/UnderworldGUI.     

Intermediate Inequality and Welfare: The Case of Spain, 1980–81 to 1990–91

The 1990–91 household expenditures distribution in Spain dominates, in the relative ("rightist") Lorenz sense, the 1980–81 distribution, but the latter dominates the former in the absolute ("leftist") Lorenz sense. This situation constitutes a textbook case for intermediate or "centrist" notions of inequality and social welfare. This paper presents the first empirical application of this sort, using the intermediate inequality concept introduced in Del Río and Ruiz-Castillo (2000). The data reveal that there is a decrease in household expenditures inequality for a relatively small set of centrist attitudes.     

Accomplice Witnesses and Organized Crime: Theory and Evidence from Italy

We develop an agency model of organized crime accounting for the main trade‐offs involved in the introduction of an accomplice‐witness program. We characterize the optimal policy and identify its main determinants in a framework where public officials can be dishonest. Our predictions are tested by using data for Italy before and after the introduction of the 1991 accomplice‐witness program. As predicted by the model and the earlier antitrust literature, the program appears to have strengthened deterrence and enhanced prosecution. Moreover, consistent with a novel prediction of our theory, the evidence suggests that the program efficacy is affected by the judicial system efficiency.     

Dynamic capital structure and the contingent capital option

The financial crisis has emphasized the difficulties for financial companies to raise funds through conventional liabilities. In this environment, hybrid securities are becoming popular. In this paper we study the optimal capital structure of a company issuing a particular type of hybrid security: perpetual contingent capital, i.e., debt that converts into equity under some conditions. A two-period model with endogenous bankruptcy for a company with equity, straight debt and contingent capital is analyzed. We investigate the instrument under different conversion rules: automatic or optimally chosen by equity holders. We show that contingent capital reduces the coupon of straight debt and expected bankruptcy costs but can require a high spread. A trigger imposed by the regulatory authority in terms of par value of debt may induce a little use of contingent capital with an increase of bankruptcy costs.