Risk taking and gender in hierarchies

In a labor market hierarchy, promotions are affected by the noisiness of information about the candidates. I study the hypothesis that males are more risk taking than females, and its implications for rates of promotion and abilities of survivors. I define promotion hierarchies with and without memory, where memory means that promotion depends on the entire history of success. In both types of hierarchies, the surviving risk takers have lower average ability whenever they have a higher survival rate. Further, even if more risk takers than non risk takers are promoted in the beginning of the hierarchy, that will be reversed over time. The risk takers will eventually have a lower survival rate, but higher ability. As a consequence of these differences, the various requirements of employment law cannot simultaneously be satisfied. Further, if promotion standards are chosen to maximize profit, the standards will reflect gender in ways that are difficult to distinguish from discriminatory intent.Labor market hierarchy, promotion, discrimination, affirmative action, hierarchy, risk taking, gender bias

Competitiveness and Corruption in Romania - Forecasting in the Context of the Romanian Integration into the European Union

Competitiveness and corruption are now - more than ever before - two real challenges for Romania on its way to the European integration. The theoretical approaches to those concepts did not get to a unanimous and happy end and the real figures that evaluate them are not at all pleasing for Romania. Our country registers low positions in the world and European hierarchies both regarding competitiveness and corruption. But, still it looks forward for its integration into the EU. The gaps that separate Romania from the European average scores are significant and by this paper we try to forecast some development directions and to estimate some time horizons in order to reduce the gaps, by significantly increasing competitiveness and diminish corruption.Competitiveness, Corruption, Forecasting, Integration, Gap Reduction

The spatial aspects of development in south-eastern Europe

This paper analyses for the first time the spatial structure of south-eastern Europe in an effort to assess regional imbalances, border conditions, urban hierarchies and detect the adjustments of the region to the forces of integration and transition. The analysis is based on a unique data base compiled from national sources and is carried on with the use of statistical, diagrammatic and cartographic methods. The analysis shows that south-eastern Europe is characterized by increasing regional disparities, an increasingly superior performance of the metropolitan regions, serious discontinuities at the borders which have, in most cases, generated over-time border regions with below average performance and finally an urban system with serious deficiencies in medium sized cities. These findings suggest that regional policy should become a permanent ingredient of indigenous and international development initiatives, which need to pay a greater attention to the needs of border regions, encouraging and promoting programs and policies of cross-border cooperation.

Works Councils and the Productivity Impact of Direct Employee Participation

This paper measures the productivity impact of management-led participative establishment practices. On the basis of a representative German establishment data set, the IAB establishment panel, the study finds that the presence of team-work, a reduction of hierarchies and autonomous work groups in 1997 significantly increases average establishment productivity in 1997 – 2000. An endogeneous switching regression model takes the endogeneity of work councils into account and shows that the productivity effect can only be measured in establishments with works councils, i.e. employee induced participation. The estimation strategy controls for unobserved time invariant establishment heterogeneity by using a two-step system GMM panel regression approach. It simultaneously controls for endogeneity of participative work organization by using instrument variable regressions. --employee participation,works council,establishment productivity,panel regression

Combinatorial approach to Modularity

Communities are clusters of nodes with a higher than average density of internal connections. Their detection is of great relevance to better understand the structure and hierarchies present in a network. Modularity has become a standard tool in the area of community detection, providing at the same time a way to evaluate partitions and, by maximizing it, a method to find communities. In this work, we study the modularity from a combinatorial point of view. Our analysis (as the modularity definition) relies on the use of the configurational model, a technique that given a graph produces a series of randomized copies keeping the degree sequence invariant. We develop an approach that enumerates the null model partitions and can be used to calculate the probability distribution function of the modularity. Our theory allows for a deep inquiry of several interesting features characterizing modularity such as its resolution limit and the statistics of the partitions that maximize it. Additionally, the study of the probability of extremes of the modularity in the random graph partitions opens the way for a definition of the statistical significance of network partitions.Comment: 8 pages, 4 figure

The effects of seed size and maternal origin on the distribution of individual plant size in Ludwigia leptocarpa (Onagraceae)

Seed size is normally distributed for many annual species, while mature plant size is frequently positively skewed. A study was conducted to determine the influence of seed size and the role of genetic differences in determining relative seedling size for Ludwigia leptocarpa. Seed size had a significant effect on percentage germination and time of seed germination but no effect on dry weight or leaf area of seedlings. Seed size and spacing had a significant effect on seedling dry weight for plants grown under competition, while relative day of emergence had no effect. Familial (genetic) differences were found in average seed weight between maternal plants, but not in average number of days to germination, average weight of seeds which germinated, or shoot dry weight. It is concluded that neither seed size alone nor genetic differences between plants are directly responsible for the development of size hierarchies in Ludwigia leptocarpa populations. Large seed size does convey an advantage in growth when plants from seeds of differing initial size interact

Hierarchical mutual information for the comparison of hierarchical community structures in complex networks

The quest for a quantitative characterization of community and modular structure of complex networks produced a variety of methods and algorithms to classify different networks. However, it is not clear if such methods provide consistent, robust and meaningful results when considering hierarchies as a whole. Part of the problem is the lack of a similarity measure for the comparison of hierarchical community structures. In this work we give a contribution by introducing the {\it hierarchical mutual information}, which is a generalization of the traditional mutual information, and allows to compare hierarchical partitions and hierarchical community structures. The {\it normalized} version of the hierarchical mutual information should behave analogously to the traditional normalized mutual information. Here, the correct behavior of the hierarchical mutual information is corroborated on an extensive battery of numerical experiments. The experiments are performed on artificial hierarchies, and on the hierarchical community structure of artificial and empirical networks. Furthermore, the experiments illustrate some of the practical applications of the hierarchical mutual information. Namely, the comparison of different community detection methods, and the study of the consistency, robustness and temporal evolution of the hierarchical modular structure of networks.Comment: 14 pages and 12 figure

Lower Bounds in the Preprocessing and Query Phases of Routing Algorithms

In the last decade, there has been a substantial amount of research in finding routing algorithms designed specifically to run on real-world graphs. In 2010, Abraham et al. showed upper bounds on the query time in terms of a graph's highway dimension and diameter for the current fastest routing algorithms, including contraction hierarchies, transit node routing, and hub labeling. In this paper, we show corresponding lower bounds for the same three algorithms. We also show how to improve a result by Milosavljevic which lower bounds the number of shortcuts added in the preprocessing stage for contraction hierarchies. We relax the assumption of an optimal contraction order (which is NP-hard to compute), allowing the result to be applicable to real-world instances. Finally, we give a proof that optimal preprocessing for hub labeling is NP-hard. Hardness of optimal preprocessing is known for most routing algorithms, and was suspected to be true for hub labeling