This paper presents results of eight experimental tests carried to evaluate the mechanical performance of unconnected "W" stirrups.Reinforced concrete wide beams were tested and their characteristics were idealized to represent column strips in flat slab buildings. The main variables were: the type of shear reinforcement; the shear span to effective depth ratio (av/d); and the flexural (ρl) and shear (ρw) reinforcement ratios. In general, both the response and the shear resistance of the structural elements with unconnected "W" stirrups was similar to those elements with vertical closed stirrups. Increments of shear resistance of up to 84% were achieved, indicating that they have high potential for use as shear reinforcement in slab-column connections.

The White-naped Jay Cyanocorax cyanopogon (Wied, 1821) is an omnivorous and opportunistic species, with a multifarious diet. In view of the scarcity of available data in the literature, the aim was to investigate and describe the bird's diet, location of food items, foraging tactics, actual feeding behavior and intraspecific interactions, as a means of defining the items consumed. The study was carried out in a Cerrado area in the Araguaia Campus of the Federal University of Mato Grosso -UFMT, in Pontal do Araguaia, Mato Grosso State, Brazil, from August to December, 2006, and from April to October, 2010. All the feeding events were recorded through 136 hours of animal focal sampling, whereby it was shown that these birds predominantly consume animal nutrients, replenished by vegetable items and human food-waste. Arthropods were predominant in the diet, with ants as the most abundant and frequent item. The fruits, flowers and seeds of eleven plant species were also consumed. Food-waste, representing about 1/10 of the total, was constantly consumed even when other food sources were available. Although active among the various strata, foraging is mainly on the ground. In the event of food-scarcity, the strategy employed is the hierarchical deployment of the members of various-sized groups, with the avoidance of direct competition. This versatility during all seasons, confirms total adaptation to the anthropic environment surrounded by native habitats that characterized the study site.Keywords: anthropic environment, Cerrado, intraspecific interactions, food items, social organization. Dieta e comportamento alimentar de

One of the core issues in community ecology is the understanding of mechanisms that determine community structure. In this study, we examine how two structurally distinct habitats (campo sujoa grassy savanna habitat with low shrubby coverand seasonal semi-deciduous forest) and distinct hydrological seasons (dry and rainy) influence the taxonomic, functional and phylogenetic diversity of lizard assemblages in a savanna area in the Brazilian Cerrado. We used pitfall traps to sample lizards from May 2000 to February 2002. To quantify spatio-temporal changes in the lizard assemblages, we used parameters of taxonomic (species richness -SR), functional (functional diversity -SES.FD, functional redundancy -FR and functional dispersion -FDis), and phylogenetic diversity (phylogenetic species richness -PSR and phylogenetic species variability -PSV). We also estimate functional and phylogenetic structure of the assemblages in each habitat during dry and rainy seasons. We recorded 182 lizards distributed among 14 species. Species composition differed among habitat types, but did not differ seasonally within habitats. SES.FD, FDis, and FR also differed among habitat types but not among seasons, with SES.FD and FDis being greater in seasonal semi-deciduous forest, while FR was greater in campo sujo. SR, PSR, and PSV were not influenced by the factors analysed. The lizard assemblage of campo sujo was functionally clustered in the dry season and phylogenetically clustered in the rainy season. These results demonstrate that differences among habitat types and seasons are important in shaping the taxonomic, functional, phylogenetic diversity and structure of lizard assemblages in the savanna area studied. Our study also demonstrates the importance of using different measures of diversity to obtain a better understanding on the mechanisms that influence the lizard assemblages in a highly seasonal environment.

Differences in habitat complexity and structure can directly influence the composition, diversity, and structure of species assemblages. Measurements of functional and phylogenetic diversity complement the commonly used measurements of taxonomic diversity, elucidating the relationships between species, their traits, and their evolutionary history. In this study, we evaluated how the mosaic of open and forested formations in a federal conservation unit in the western portion of the Brazilian Cerrado savanna influences the taxonomic, functional, and phylogenetic structure of lizard assemblages. Lizards were sampled for 15 months using pitfall traps set in open and forested formations. We recorded 292 lizards distributed among 16 species from eight families, with species composition differing among the formations. Richness was greater in the assemblages from open formations, while functional diversity and phylogenetic variability were greater in those of forested formations. Lizard assemblages in open formations were functionally and phylogenetically clustered, probably as a result of environmental filters acting on species, while the assemblages from forested formations were randomly structured. Different environmental and historical mechanisms have apparently shaped the current diversity of lizards in the region. This study shows that Cerrado vegetation mosaics can promote wide variation in different aspects of the taxonomic, functional, and phylogenetic structure from the lizard assemblages.

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