Unexpected robustness against noise of a class of nonhyperbolic chaotic attractors

Chaotic attractors arising in physical systems are often nonhyperbolic. We compare two sources of nonhyperbolicity: (1) tangencies between stable and unstable manifolds, and (2) unstable dimension variability. We study the effects of noise on chaotic attractors with these nonhyperbolic behaviors by investigating the scaling laws for the Hausdorff distance between the noisy and the deterministic attractors. Whereas in the presence of tangencies, interactive noise yields attractor deformations, attractors with only dimension variability are robust, despite the fact that shadowing is grossly violated

Unexpected robustness against noise of a class of nonhyperbolic chaotic attractors

Chaotic attractors arising in physical systems are often nonhyperbolic. We compare two sources of nonhyperbolicity: (1) tangencies between stable and unstable manifolds, and (2) unstable dimension variability. We study the effects of noise on chaotic attractors with these nonhyperbolic behaviors by investigating the scaling laws for the Hausdorff distance between the noisy and the deterministic attractors. Whereas in the presence of tangencies, interactive noise yields attractor deformations, attractors with only dimension variability are robust, despite the fact that shadowing is grossly violated

Turismo rural, empreendedorismo e gênero: um estudo de caso na comunidade autônoma da Galiza

Neste trabalho indagamos sobre possíveis diferenças no comportamento empreendedor em turismo rural; estabelecemos características e dimensões motivadoras em função do gênero. Num exemplo representativo de estabelecimentos de turismo rural da Comunidade Autônoma da Galiza (Espanha), encontramos relação entre gênero e importância da compatibilização de atividades agrárias e tumrísticas, e entre gênero e perfil das motivações para empreender atividades de turismo rural. As mulheres estão mais motivadas por elementos do âmbito econômico e, portanto, na tomada de decisões, têm mais relevância os critérios de racionalidade econômica unidos à estratégia de diversificação da atividade agrária em favor da sobrevivência financeira. Ao contrário do estabelecido na maior parte da literatura, os fatores de índole social, familiar ou institucional têm a mesma importância para homens e mulheres. Aliás, verificase a ausência de relação entre gênero e características pessoais (como idade e formação e necessidades financeiras do empreendedor)

Stochasticity of Bacterial Attachment and Its Predictability by the Extended Derjaguin-Landau-Verwey-Overbeek Theory▿

Bacterial attachment onto materials has been suggested to be stochastic by some authors but nonstochastic and based on surface properties by others. We investigated this by attaching pairwise combinations of two Salmonella enterica serovar Sofia (S. Sofia) strains (with different physicochemical and attachment properties) with one strain each of S. enterica serovar Typhimurium, S. enterica serovar Infantis, or S. enterica serovar Virchow (all with similar physicochemical and attachment abilities) in ratios of 0.428, 1, and 2.333 onto glass, stainless steel, Teflon, and polysulfone. Attached bacterial cells were recovered and counted. If the ratio of attached cells of each Salmonella serovar pair recovered was the same as the initial inoculum ratio, the attachment process was deemed stochastic. Experimental outcomes from the study were compared to those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Significant differences (P < 0.05) between the initial and the attached ratios for serovar pairs containing S. Sofia S1296a for all different ratios were apparent for all materials. For S. Sofia S1635-containing pairs, 7 out of 12 combinations of serovar pairs and materials had attachment ratios not significantly different (P > 0.05) from the initial ratio of 0.428. Five out of 12 and 10 out of 12 samples had attachment ratios not significantly different (P > 0.05) from the initial ratios of 1 and 2.333, respectively. These results demonstrate that bacterial attachment to different materials is likely to be nonstochastic only when the key physicochemical properties of the bacteria were significantly different (P < 0.05) from each other. XDLVO theory could successfully predict the attachment of some individual isolates to particular materials but could not be used to predict the likelihood of stochasticity in pairwise attachment experiments