On total and edge coloring some Kneser graphs

Journal of Combinatorial Optimization - In this work, we investigate the total and edge colorings of the Kneser graphs K(n, s). We prove that the sparse case of Kneser graphs, the odd...     

Exact algorithms for scheduling programs with shared tasks

We study a scheduling problem where the jobs we have to perform are composed of one or more tasks. If two jobs sharing a non-empty subset of tasks are scheduled on the same machine, then these shared tasks have to be performed only once. This kind of problem is known in the literature under the names of VM-PACKING or PAGINATION. Our objective is to schedule a set of these objects on two parallel identical machines, with the aim of minimizing the makespan. This problem is NP-complete as an extension of the PARTITION problem. In this paper we present three exact algorithms with worst-case time-complexity guarantees, by exploring different branching techniques. Our first algorithm focuses on the relation between jobs sharing one or more symbols in common, whereas the two other algorithms branches on the shared symbols.

     

Returns to Education during the Reform of State‐owned Enterprises in Hunan,People’s Republic of China

The objective of this paper is to analyse the impact of education on personal earnings during the reform of state‐owned enterprises, comparing 1995 with 1998 in Hunan, China, using the Mincerian earnings equation method. The results show that the rates of return to education increased, indicating that human capital has been better rewarded as the reforms of the Chinese economic structure have progressed. Moreover, the findings show that primary education receives the highest returns, followed by tertiary education. Middle school education obtains the lowest rewards, reflecting the effects of the reform of state‐owned enterprises on middle school graduates on whom the unemployment impact of this change has been the greatest.     

Influence of habitat type and distance from source area on bird taxonomic and functional diversity in a Neotropical megacity

The Neotropical region has been subjected to massive urbanization, which poses high risks for some global biodiversity hotspots and losses of ecosystem functions and services. In this study, we investigate how distance from large patches of native forests (source areas) and vegetation (green)/and infrastructure (gray) characteristics affect bird species richness and functional diversity in São Paulo megacity, southeastern Brazil. We analyzed the effects of source areas and green/gray characteristics on species richness and functional diversity (richness, evenness, and divergence) indices. We detected 231 bird species, and our data confirmed our predictions: (1) bird species richness in urbanized habitats was found to be (~?50–85%) lower than in source habitats; (2) species richness and trait composition significantly decreased as the distance from the source area increased, while functional richness was not affected by this metric; and (3) shrub and herbaceous covers and maximum height of trees were positively correlated with species richness and unique functional traits regarding habitat, diet, foraging and nesting strata and dispersal ability of birds in the forest-urban matrix. The number of buildings was negatively correlated with bird species richness and functional richness. Maximum height of buildings caused dramatic declines in functional evenness. Functional divergence was notably lower in sites with high shrub cover. Our study stresses the complexity of vegetation embedded in large Neotropical urban settlements and the need to maintain large protected areas surrounding megacities to mitigate the impacts of urbanization on birds.

     

Free time,gender and the pandemic: An exploration of children's daily routines in the times of COVID-19 in Chile

This article discusses the differentiation by gender displayed by children between 8 and 12 years old on how they used their free time during the COVID-19 pandemic in Chile. This study had a qualitative approach, where 43 in-depth interviews were conducted with children from three different regions of the country, using participatory photo-elicitation as the central tool. The main results of the study show a configuration of free time based on gender stereotypes, showing that boys are the ones who most adhere to such stereotypes, triggering a crisis in the identity construction of masculinities during childhood. The study also suggests that socioeconomic and territorial differences between children configures different experiences of the use of free time.