Wind loads on open truss structures: applications of blockage to historic transporter bridges.

The overall aim of this study is to compare and contrast the design of the two remaining working examples of early twentieth-century transporter bridges in the UK, namely, those at Newport and Middlesbrough. With the aid of modern finite-element analysis, the behaviour of the structures under loading is investigated, likely modes of failure determined and the efficiency of each structure evaluated. The important horizontal load component due to wind at the exposed locations of the bridges is examined using 'current blockage', ideas transferred from recent work on wave-current-structure interaction for space-frame structures in offshore engineering. This article is part of the theme issue 'Environmental loading of heritage structures'.

Decadal variability of extreme wave height representing storm severity in the northeast Atlantic and North Sea since the foundation of the Royal Society.

Long-term estimation of extreme wave height remains a key challenge because of the short duration of available wave data, and also because of the possible impact of climate variability on ocean waves. Here, we analyse storm-based statistics to obtain estimates of extreme wave height at locations in the northeast Atlantic and North Sea using the NORA10 wave hindcast (1958-2011), and use a 5 year sliding window to examine temporal variability. The decadal variability is correlated to the North Atlantic oscillation and other atmospheric modes, using a six-term predictor model incorporating the climate indices and their Hilbert transforms. This allows reconstruction of the historic extreme climate back to 1661, using a combination of known and proxy climate indices. Significant decadal variability primarily driven by the North Atlantic oscillation is observed, and this should be considered for the long-term survivability of offshore structures and marine renewable energy devices. The analysis on wave climate reconstruction reveals that the variation of the mean, 99th percentile and extreme wave climates over decadal time scales for locations close to the dominant storm tracks in the open North Atlantic are comparable, whereas the wave climates for the rest of the locations including the North Sea are rather different.

Effects of isolation and environmental variables on fish community structure in the Brazilian Amazon Madeira-Purus interfluve.

Due to the existence of terrestrial barriers to freshwater fish dispersion, it is believed that its distribution is strongly associated with historical factors related to the formation of the habitats they occupy. By the other hand, some studies reveal the influence of abiotic conditions (such as size of water bodies, pH, conductivity) on the composition of fish fauna occurring in small streams. This study aimed to investigate whether drainage basins, because catchment boundaries are potential barriers to fish dispersion, or the physical structure and physico-chemical characteristics of water have a greater influence on fish community structure in small streams. We sampled 22 streams belonging to five drainage basins in the Madeira-Purus interfluve. Fish were caught with dip nets and a small trawl, and data were simultaneously obtained on structural characteristics of the streams and physico-chemical characteristics of the water. Community composition was analyzed using Non-Metric Multidimensional Scaling (NMDS), and variables related to structural and physico-chemical characteristics were summarized by Principal Component Analysis (PCA). Two explanatory models relating faunal composition to environmental factors were constructed: the first using only continuous variables and the second including the drainage basin as a categorical variable. The Akaike Information Criterion (AIC) and AIC weight were used to select the best model. Although structural and physico-chemical variables significantly contributed to explaining faunal composition, the model including the drainage basin was clearly the better of the two models (more than 90% support in the data). The importance of drainage basins in structuring fish communities in streams may have significant consequences for conservation planning in these environments.

Mutagenic activities of tryptophan metabolites before and after nitrite treatment.

The mutagenic activities of 16 kinds of tryptophan metabolites, before and after nitrite treatment, were examined in the Ames test. None of the compounds showed mutagenic activity before nitrite treatment. After nitrite treatment under acidic conditions, 11 compounds showed mutagenic activity towards Salmonella typhimurium TA100 strain in the absence of a metabolic activation system. Tryptophan induced 1000 revertant colonies/mumol, while 5-hydroxyindole, 5-hydroxytryptamine and 3-hydroxykynurenine, all containing a hydroxy group in the molecule, induced 11,000, 5200 and 2700 revertant colonies/mumol, respectively. These results indicate that the introduction by nitrite treatment of a hydroxy group into the indole or benzene ring of tryptophan-related compounds increases their mutagenic activity.

Improved 4-aminoantipyrine colorimetry for detection of residual hydrogen peroxide in noodles, fish paste, dried fish, and herring roe.

Improved 4-aminoantipyrine (4-AA) colorimetry was developed for the detection of minute quantities of residual hydrogen peroxide in several kinds of food. Hydrogen peroxide in the sample was stabilized with potassium bromate and extracted with cold methanol. The methanol extract was diluted with phosphate buffer, protein was eliminated with zinc sulfate, and the extract was reacted with phenol, 4-AA, and peroxidase to the stable quinoneimine dye. The weak color solution was purified with Florisil column chromatography, concentrated, and determined by colorimetry. Recoveries of hydrogen peroxide from samples fortified at 0.5, 2, and 10 ppm ranged from 70.7 +/- 8.9 to 98. 5 +/- 1.2%. Color development was linear with amount of H2O2 from 0.5 to 20 micrograms, corresponding to 0.05-2 ppm in samples.