Nonintersecting paths with a staircase initial condition

We consider an ensemble of $N$ discrete nonintersecting paths starting from equidistant points and ending at consecutive integers. Our first result is an explicit formula for the correlation kernel that allows us to analyze the process as $N\to \infty$. In that limit we obtain a new general class of kernels describing the local correlations close to the equidistant starting points. As the distance between the starting points goes to infinity, the correlation kernel converges to that of a single random walker. As the distance to the starting line increases, however, the local correlations converge to the sine kernel. Thus, this class interpolates between the sine kernel and an ensemble of independent particles. We also compute the scaled simultaneous limit, with both the distance between particles and the distance to the starting line going to infinity, and obtain a process with number variance saturation, previously studied by Johansson.Comment: 34 pages, 9 figures; reference added, Theorem 2.1 extended, typos correcte

A Best evidence synthesis on the link between budgetary participation and managerial performance

By using the best evidence synthesis (Slavin, 1995), we want to find out an accurate synthesis on the budgetary participation -BP- and managerial performance-PM- link. The use of criteria of selection has allowed to decrease the heterogeneity. The results explain the presence of the heterogeneity by cultural and industrial contengencies. The best evidence synthesis based on an homogeneous subgroup (managers in publicly traded firms in Taiwan Stock Exchange) shows a time dependency of BP-MP link and some recommandations for further research: 1/to continue the study of the traded firms in Taiwan Stock Exchange to analyse the causal BP-PM link with a Granger test, 2/to study the evolution of this link over time in other countries.best evidence synthesis, subgroup analysis, managerial performance, budgetary participation, management control

Income Redistribution and Public Good Provision: an Experiment

We provide a new experimental investigation of the neutrality theorem of Warr (1983), who states ”when a single public good is provided at positive levels by private individuals, its provision is unaffected by a redistribution of income”. Instead of comparing different income distributions across groups as Chan et al. (1996), in our experiment the total group endowment is redistributed after a 10 rounds sequence. We compare an unequalizing redistribution (EI) and an equalizing redistribution (IE), to two benchmark treatments for which the 10 rounds sequence is repeated, either with an equal distribution (EE) or an unequal distribution (II). The constituent game has a unique interior dominant strategy equilibrium. Our data support the neutrality theorem (after controlling for the restart effect): redistribution has no effect on the total amount of public good in none of the tested treatments. However, the analysis of individual behavior shows that ”poor” subjects over-contribute with respect to their Nash-contribution, while ”rich” subjects tend to play their Nash-contribution or under-contribute slightly. Furthermore, after a redistribution, subjects react asymetrically: subjects who get poorer reduce their contribution of a larger amount than the amount of contribution added by subjects who become richer. And it is shown that the latter do not react enough to the redistribution.

Continuous use of authoring for adaptive educational hypermedia : a long-term case study

Adaptive educational hypermedia allows lessons to be personalized according to the needs of the learner. However, to achieve this, content must be split into stand-alone fragments that can be processed by a course personalization engine. Authoring content for this process is still a difficult activity, and it is essential for the popularization of adaptive educational hypermedia that authoring is simplified, so that the various stakeholders in the educational process, students, teachers, administrators, etc. can easily work with such systems. Thus, real-world testing with these stakeholders is essential. In this paper we describe recent extensions and improvements we have implemented in the My Online Teacher MOT3.0 adaptation authoring tool set, based on an initial set of short-term evaluations, and then focus on describing a long-term usage and assessment of the system

Export Dynamics in Colombia: Transactions Level Evidence

We examine Colombian export transaction data from customs records in several dimensions. We begin with some basic statistics on the number and frequency of export transactions by a firm, overall and across individual markets. We then decompose the variation in overall exports into the number of transactions and the size of the average transaction, both at the aggregate level and for individual firms to explore gravity equations, where the patterns of exports and numbers of transactions are related to the distance with respect to the destination. The analysis is carried out both at the aggregate and the firm level. Then we explore the relationship between patterns of transactions numbers and shipment modes. Our results show great heterogeneity in the patterns of frequency and number of transactions across firms; the average firm sent about 75 shipments abroad in 2005, while the firm with largest number of transactions that same year dispatched more than 26,000 shipments. Moreover, while close to 35% of firms in the sample report a single export transaction over the period, for most firms with multiple transactions the average span between two transactions is less than a month. Part of this heterogeneity is shown to be related to the distance with respect to the destination market: firms exporting to more distant destinations make less frequent shipments than firms exporting to markets that are closer. This suggests that there are fixed costs per shipment inducing declining marginal cost of higher shipment volume. These patterns imply that, at the aggregate level, transactions numbers are the primary source of variation in exports. The variability in the numbers of transactions also explains an important part of the well-known negative relationship between aggregate exports and distance to a specific destination.Export transaction frequency; fixed shipment costs and scale economies in transportation; destination distance, average shipment volume and number of shipments. Classification JEL: F10; F12; F14.

Export Dynamics in Colombia: Firm-Level Evidence

Using transactions-level customs data from Colombia, we study firm-specific export patterns over the period 1996-2005. Our data allow us to track firms' entry and exit into and out of individual destination markets, as well as their revenues from selling there. We find that, in a typical year, nearly half of all Colombian exporters were not exporters in the previous year. These new exporters tend to be extremely small in terms of their overall contribution to export revenues, and most do not continue exporting in the following year. Hence export sales are dominated by a small number of very large and stable exporters. Nonetheless, out of each cohort of new exporters, a fraction of firms go on to expand their foreign sales very rapidly, and over the period of less than a decade, these successful new exporters account for almost half of total export expansion. Finally, we find that new exporters begin in a single foreign market and, if they survive, gradually expand into additional destinations. The geographic expansion paths they follow, and their likelihood of survival as exporters, depend on their initial destination market.