Depth of segments and circles through points enclosing many points: a note

Neumann-Lara and Urrutia showed in 1985 that in any set of n points in the plane in general positionthere is always a pair of points such that any circle through them contains at least (n-2)/60 points. In a series of papers, this result was subsequently improved till n/4.7, which is currently the best known lower bound. In this paper we propose a new approach to the problem that allows us, by using known results about j-facets of sets of points in $R^3$, to give a simple proof of a somehow stronger result: there is always a pair of points such that any circle through them has, both inside and outside, at least n/4.7 points.Comment: 5 pages, 2 figure

Domestic transport cost reductions and firms’ export behaviour

Transport infrastructure investment reduces the cost of distance and enables firms to establish and maintain contacts over larger distances. Spain has developed an ambitious road building programme over the last decades, which has considerably reduced transport costs to access European markets. In this paper we depart from the traditional aggregate approach in analysing the impacts of transport infrastructure investment. In particular, we examine the export decision of Spanish manufacturing firms and test how domestic transport cost reductions affect firms’ probability of becoming exporters. We estimate models that control for unobserved heterogeneity among firms, endogeneity and initial conditions problems. Our results provide some support for a positive effect of domestic transport improvements on firms’ exporting probability. However, the magnitude of this effects is small, being the strongest effect the one due to previous export experience which suggests high entry costs into export markets

Transport infraestructure, sunk costs and firms' export behaviour

Transport infrastructure investment reduces the cost of distance and enables firms to establish contacts over larger distances. We study the impact of transport-cost reductions on firms’ export behaviour, accounting for the role of entry costs and other firms’ characteristics. Using Spanish data we estimate dynamic probability models controlling for firms’ unobserved heterogeneity and for the simultaneity of firms’ export and location decisions. Our results provide support for a positive effect of domestic transport improvements on firms’ exporting probability for small and medium sized firms. We find a strong effect of previous export experience, suggesting high entry costs into export markets

Transport infraestructure, sunk costs and firms' export behaviour

Transport infrastructure investment reduces the cost of distance and enables firms to establish contacts over larger distances. We study the impact of transport-cost reductions on firms’ export behaviour, accounting for the role of entry costs and other firms’ characteristics. Using Spanish data we estimate dynamic probability models controlling for firms’ unobserved heterogeneity and for the simultaneity of firms’ export and location decisions. Our results provide support for a positive effect of domestic transport improvements on firms’ exporting probability for small and medium sized firms. We find a strong effect of previous export experience, suggesting high entry costs into export markets.Export decision, Transport infrastructure, Accessibility, Dynamic panel data

Algorithmic Perception of Vertices in Sketched Drawings of Polyhedral Shapes

In this article, visual perception principles were used to build an artificial perception model aimed at developing an algorithm for detecting junctions in line drawings of polyhedral objects that are vectorized from hand-drawn sketches. The detection is performed in two dimensions (2D), before any 3D model is available and minimal information about the shape depicted by the sketch is used. The goal of this approach is to not only detect junctions in careful sketches created by skilled engineers and designers but also detect junctions when skilled people draw casually to quickly convey rough ideas. Current approaches for extracting junctions from digital images are mostly incomplete, as they simply merge endpoints that are near each other, thus ignoring the fact that different vertices may be represented by different (but close) junctions and that the endpoints of lines that depict edges that share a common vertex may not necessarily be close to each other, particularly in quickly sketched drawings. We describe and validate a new algorithm that uses these perceptual findings to merge tips of line segments into 2D junctions that are assumed to depict 3D vertices

Inequality for wage earners and self-employed : evidence from panel data

In this paper we study the evolution of income inequality for employees and self-employed workers. We highlight the importance of separately analyze these different sources of income to gain a broader understanding of inequality. Using Spanish panel data on income and consumption from the ECPF for the period 1987-96, we decompose income shocks into a permanent and a transitory component. We find that there are noticeable differences in the evolution of income inequality, as well as in the relative importance of the permanent and transitory components across these groups. Our results points that the evolution of inequality can be basically explained by movements in the transitory component of income for the self-employed, while for the employees it is mainly driven by the permanent component, specially at the end of the period. Given these disparities, it seems that these two sources of income should be studied separately and that different policies are suitable for each group.

Inequality for Wage Earners and Self-Employed: Evidence from Panel Data

Published as an article in: Oxford Bulletin of Economics and Statistics, 2009, vol. 71, issue 4, pages 491-518.transitory income inequality, consumption, permanent income inequality, self-employment, panel data

Resource-Based View and SMEs Performance Exporting through Foreign Intermediaries: The Mediating Effect of Management Controls

Following the resource-based view, this research empirically explores the role of formal and informal management control in mobilizing export resources to develop export capabilities, influencing the export performance of small and medium-sized enterprises (SMEs) in an interorganizational relationship context. Empirical data were collected using a survey administrated online to finance managers in Spanish SMEs which use foreign intermediaries to access export markets. In this setting, evidence mainly suggests, first, that management control systems (MCSs) play a relevant mediating role between the effect of, on the one hand, resources on capabilities, and, on the other hand, resources and capabilities on performance. Second, that MCSs and capabilities play a interrelated double mediating effect between the impact of resources on performance; more specifically, a significant double indirect effect is found (1) between financial resources, behavior control, customer relationship building capability and performance, and (2) between physical resources, behavior control, customer relationship building capability and performanc

Os Centros de Apoio à Criação de Empresas enquanto promotores do desenvolvimento regional

Comunicação apresentada no 12º Congresso da APDR, ViseuEste trabalho analisa o contributo dos CACE, incubadoras empresariais, para a promoção do desenvolvimento regional. Baseado em 6 entrevistas aos Directores destas estruturas e em 21 estudos de caso de empresas incubadas, para além da análise dos relatórios de actividades no período 2000-2004, foi possível constatar que estas incubadoras dirigidas a promover o desenvolvimento económico desempenham um papel relevante no aparecimento e sustentabilidade de novas empresas, promovendo também a temática do empreendedorismo. As novas empresas criadas reflectem, na maioria dos casos, uma capacidade de gerar serviços e produtos inovadores para as regiões em causa, promovendo o desenvolvimento regional. Estamos na presença de uma nova geração de empreendedores, 70% possui o grau de licenciatura, capazes de gerar empregos mais qualificados, quando tomamos por comparação a média nacional, ao mesmo tempo que fixam capital humano elevado em regiões carenciadas

Entrepreneurship, methodologies in higher education an experience in a portuguese business school

Today entrepreneurship education is an important issue to improve the process of creating new firm assuming new risks and rewards. The theoretical discussion about around the question: “Entrepreneurs are born or made?” assume that is possible educate to be entrepreneurs. Schools have an important role in this process. Believing in this possibility our Business School developed a set of pedagogical methodologies supported in apprenticeship based on “learning by doing”. This pedagogical methodology was created through a study of best practices. This study aims to propose a set of innovative methodologies and students perceptions about their apprenticeship experience/process. The study concludes with a set of recommendations and a best practices manual useful to appliance in higher education.Innovative methodologies; entrepreneurship education; learning by doing