Chaos in Anisotropic Pre-Inflationary Universes

We study the dynamics of anisotropic Bianchi type-IX models with matter and cosmological constant. The models can be thought as describing the role of anisotropy in the early stages of inflation. The concurrence of the cosmological constant and anisotropy are sufficient to produce a chaotic dynamics in the gravitational degrees of freedom, connected to the presence of a critical point of saddle-center type in the phase space of the system. The invariant character of chaos is guaranteed by the topology of the cylinders emanating from unstable periodic orbits in the neighborhood of the saddle-center. We discuss a possible mechanism for amplification of specific wavelengths of inhomogeneous fluctuations in the models. A geometrical interpretation is given for Wald's inequality in terms of invariant tori and their destruction by increasing values of the cosmological constant.Comment: 14 pages, figures available under request. submitted to Physical Review

Morphological asymmetry and broiler welfare

Health status, feed conversion ratio, and mortality are long known broiler chicken production indicators. However, further parameters are required by today's demanding meat markets, as these indicators are not sufficiently accurate to determine flock overall welfare. Morphological asymmetry has been pointed as an alternative welfare indicator as it reflects the ability of the bird to cope with the challenges that rearing conditions may impose. This study aimed at evaluating the possibility of using morphological asymmetry as a welfare indicator. Broilers from 28 to 42 days of age were used in the trial. Birds were randomly selected in a commercial poultry farm and transported to the laboratory. They walked over the force measurement platform in order to determined their feet force as a percentage of body weight. The following body parts of the live birds were measured by two different operators using a digital caliper: tarsometatarsus length, outertoe length, midtoe length, and backtoe length. In the corresponding carcasses, the following traits were measured: wattle width, eye length, and first secondary feather length. Data were submitted to statistical analyses and no correlation was found between specific feet trait measurements and walking ability. Considering the time budget involved in measuring morphological asymmetry, this procedure did not appear to be a practically feasible welfare indicator.209213Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Co-operative inhibitory effects of hydrogen peroxide and iodine against bacterial and yeast species.

BACKGROUND: Hydrogen peroxide and iodine are powerful antimicrobials widely used as antiseptics and disinfectants. Their antimicrobial properties are known to be enhanced by combining them with other compounds. We studied co-operative inhibitory activities (synergism, additive effects and modes of growth inhibition) of hydrogen peroxide and iodine used concurrently against 3 bacterial and 16 yeast species. RESULTS: Synergistic or additive inhibitory effects were shown for hydrogen peroxide and iodine mixtures against all 19 species used in the study. Both biocides were mostly cidal individually and in mixtures against Pseudomonas aeruginosa and Staphylococcus aureus. Both compounds manifested static inhibitory effects individually, but their mixtures were synergistically cidal for Saccharomyces cerevisiae and Escherihia coli. Cells of S. cerevisiae treated with hydrogen peroxide and iodine-hydrogen peroxide mixture produced increased numbers of respiratory deficient mutants indicating genotoxic effects. CONCLUSION: Iodine and hydrogen peroxide used concurrently interact synergistically or additively against a range of prokaryotic and eukaryotic microorganisms. The study provides an insight as to how these traditional antimicrobials could be used more effectively for disinfection and antisepsis. In addition, a simple approach is proposed for scoring genotoxicity of different biocides by using the budding yeast system

Cyclic tensile-compressive tests on thin concrete boundary elements with a single layer of reinforcement prone to out-of-plane instability

The growing need for residential housing in Latin American countries has led to the construction of reinforced concrete buildings with wall thicknesses as low as 8–10 cm. Such walls have typically only a single layer of vertical rebars and are therefore particularly susceptible to out-of-plane failure. In order to investigate the response of the corresponding wall boundary elements, twelve reinforced concrete members with a single layer of vertical rebars were tested under tension–compression cycles. The objective was to gain insight into the parameters governing wall instability and out-of-plane failure, namely the thickness, reinforcement ratio, and eccentricity of the longitudinal rebars with respect to the member axis. This paper summarises the results of the test program, where the specimens' response is analysed also at the global and local levels. The results show that the crack pattern has an important influence on the out-of-plane behaviour and the conditions leading to out-of-plane failure are described. Furthermore, the differences between members with a single layer of vertical rebars and members with two layers are discussed. The influence of the parameters considered in the experimental program is addressed, showing that sections with small thickness and large reinforcement content are more prone to out-of-plane failures. Finally, predictions given by existing models are compared to the new experimental data. The entire data set is publicly available. © 2017 Springer Science+Business Media B.V