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The equatorial plasma bubble evolution, its symmetric propagation away from the equator over north/south hemispheres, the vertical plasma drift asymmetry, and some implications between these phenomena are examples of the conjugate point experiment campaign results. However, the asymmetric transport of plasma may imply a distinct ionospheric background in each hemisphere. When the equatorial depletion reaches these regions, the ionospheric scintillation may present different patterns. In this work, data from scintillation monitors, ionosondes, and all-sky imagers deployed at geomagnetically antipodal stations around the equator during the campaign were evaluated along the months of October–December 2002. The results reveal asymmetries in the onset times and scintillation magnitudes. On the one hand, the scintillation onset occurred earlier in 80% of the cases over the southern hemisphere. On the other hand, 71% of the nights verified the larger scintillation values in the northern hemisphere. The distinct F region altitudes, thickness, bottomside electron density gradient scale lengths, and TEC over both stations seem to contribute to this asymmetric behavior. [ABSTRACT FROM AUTHOR]

In Brazil, safe drinking water is not widely available, and consequently waterborne diseases are still associated with high morbidity and mortality rates. Among waterborne bacteria, diarrheagenic Escherichia coli (DEC) should be highlighted. This study targeted the evaluation of enteropathogenic (EPEC), enterotoxigenic (ETEC), and shiga toxin-producing (STEC)/enterohemorrhagic Escherichia coli in drinking water in Southeast Brazil and the georeferencing of generated data. A total of 1185 water samples were studied. Among them 7.8% and 4.1% gave positive results for total and fecal coliforms, respectively. By employing PCR, a total of 12 diarrheagenic E. coli (DEC) isolates (6 ETEC, 4 STEC, and 2 EPEC) from eight water samples (4, 2, and 2 positives for STEC, ETEC, and EPEC, respectively) were detected including samples collected in schools and a healthcare facility where particularly susceptible hosts are found. Data generated were submitted to georeferencing. A positive correlation (r2 = 0.9) between DEC detection and the rainy period was observed. The presence of DEC in drinking water samples in the studied municipalities highlights the relevance of controlling the sources of human and animal fecal pollution, as well as the management of municipal wastewater sources in order to reduce potential risks to human health. Searching for DEC and georeferencing DEC positive sites may subsidize the proposal of corrective and preventive actions by environmental surveillance agencies. [ABSTRACT FROM AUTHOR]

Friction joints are one of the fundamental means used for the assembly of structural components in engineering applications. The structural dynamics of these components becomes nonlinear, due to the nonlinear nature of the forces arising at the contact interface characterised by stick-slip phenomena and separation. Advanced numerical models have been proposed in the last decades which have shown some promising capabilities in capturing these local nonlinearities. However, despite the research efforts in producing more advanced models over the years, a lack of validation experiments made it difficult to have fully validated models. For this reason, experimental techniques which can provide insights into the local dynamics of joints can be of great interest for the refinement of such models and for the optimisation of the joint design and local wear predictions. In this paper, a preliminary study is presented where ultrasound waves are used to characterise the local dynamics of friction contacts by observing changes of the ultrasound reflection/transmission at the friction interface. The experimental technique is applied to a dynamic friction rig, where two steel specimens are rubbed against each other under a harmonic tangential excitation. Initial results show that, with a controlled experimental test procedure, this technique can identify microslip effects at the contact interface. [ABSTRACT FROM AUTHOR]

Edge effects threaten organisms and ecological processes in habitat remnants, but they have been poorly studied in non-humid forests such as cerradão, a tropical dry forest sometimes derived from fire-suppressed savanna in Brazil. The diverse ecosystem functions performed by arthropods may be disrupted by edge effects, and there is pressing need for more studies on this subject. We sampled fragments of cerradão facing either a road or fire breaks, assessing edge effects in: beta diversity and community composition of epigaeic (litter-dwelling) arthropod orders, ant species, and ant functional groups; ant species richness and diversity; leaf litter depth; and colony residence time of a predatory ground-dwelling ant, Odontomachus chelifer (Ponerinae). None of the variables measured differed between edge and interior of the sites sampled. Dry forests have high micro-climatic variations caused by discontinuities in the canopy cover and, as such, changes in abiotic variables in cerradão edges might not be as clear as those observed in tropical rainforests. Our study demonstrates that edge effects may not be so prevalent in cerradão facing roads or fire breaks, which possibly increases the chances of survival of a higher fraction of the original arthropod fauna compared to rainforest fragments. [ABSTRACT FROM AUTHOR]