Study of the motions of fishing vessels by a time domain panel method

In this paper, a wide variety of computed motion results is presented for three existing fishing vessels. In order to do that, time domain computations of 3D ship motions are performed with a time domain Green's function. The computational method adopted is based on a previously developed one, whose numerical scheme here is subjected to modifications that increase its robustness and overall efficiency, so that it can be applied to calculate the motions of fishing vessels. The results are then compared with simulations using WAMIT for the zero speed case, and a strip theory method is used to determine the effect of forward speed. Results are presented for head seas, quartering head waves and following waves with three distinct Froude numbers.     

The Flat Dilatometer Test in an Unsaturated Tropical Soil Site

The site characterization of unsaturated soils is well stablished based on laboratory tests, which are expensive and time-consuming. In-situ testing methods, such as the flat dilatometer test (DMT), are an alternative to the traditional approach of drilling, sampling, and laboratory testing. The literature on DMT interpretation is well established on saturated and well-behaved soils. Only few studies deal with DMT interpretation in unusual soils, and little is known about the influence of soil suction on this test. This paper presents and discusses the influence of soil suction on four DMT campaigns carried out in an unsaturated tropical soil site, also incorporating the soil suction influence on the DMT interpretation. Soil suction was estimated by the soil–water characteristic curve (SWCC) and water content profiles. The water content profiles range from 11.3 to 19.7% which corresponds to a suction range estimated by SWCCs mostly between 6 and 200 kPa. Soil suction significantly influenced DMT data up to 5 m depth at the studied site (the unsaturated active zone) increasing the intermediate DMT parameters. The average horizontal stress index (K_D) was equal to about 1.7 and the average dilatometer modulus (E_D) was about 4.7 MPa in the active zone and practically doubled their values due to in situ soil suction. The estimated peak friction angle (?) was 20–30% higher due to soil suction influence on DMT assuming the soil behaves as a sand like material. Soil suction must be considered to assess the behavior of the investigated soil by the DMT. The suction influence should be incorporated in the effective stress and this approach considerably improved the site characterization of the studied site.

     

Runoff Scaling in Large Rivers of the World

Runoff and precipitation scaling with respect to drainage area is analyzed for large river basins of the world, those with mean annual runoff in excess of 10 k³/yr. The usefulness of the specific runoff (runoff per unit drainage area, m/yr) to categorize runoff scaling laws across the complete spectrum of climatic and hydrologic conditions is evaluated. It is found that (1) runoff scales with drainage are in those river basins with specific runoff in excess of 0.15 m/yr (r² = 0.88); (2) runoff scaling with drainage area shows remarkably high statistical correlation (r²= 0.97) in river basins with specific runoff equal to or larger than 1.0 m/yr; (3) runoff does not Inc.rease with Inc.reasing drainage area in river basins with specific runoff below 0.15 m/yr, where no discernible statistical association was found between runoff and drainage area; and (4) precipitation depth (m/yr) is inversely proportional to drainage area raised to a fractional exponent in river basins with specific runoff in excess of 0.15 m/yr.     

Mesoscale and microscale shock effects in the LL6 S4 chondrites Saint‐Séverin and Elbert: A tale of two breccias

Saint‐Séverin and Elbert, two LL6 chondrite breccias, were systematically studied to evaluate multiple deformation effects on spatial scales ranging from thin section (mesoscale) to micron‐submicron (microscale) using optical microscopy, electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The different techniques provide consistent results but have complementary strengths, together providing a powerful approach to unravel even complex impact histories. Both meteorites have an S4 conventional shock stage, but interclast areas are more deformed, and clasts are more deformed in Elbert than in Saint‐Séverin. TEM and EBSD data provide compelling evidence that Saint‐Séverin experienced significant shock deformation while already hot, and cooled rapidly afterward, as a result of a major, possibly disruptive impact on the LL chondrite parent body ~4.4 Ga ago. In contrast, Elbert was shocked from a cold initial state but was heated significantly during shock, and cooled in a localized hot impact deposit on the LL asteroid. Both meteorites probably were shocked at least twice; data for Saint‐Séverin are best reconciled with a three‐impact model.     

Influence of high-pressure processing on the structure and memory effect of synthetic layered double hydroxides

We investigate the structural evolution of synthetic layered double hydroxides (LDH) samples, processed at room temperature and high-pressure (up to 7.7 GPa) in a toroidal chamber with two pressure-transmitting media, lead and graphite, using X-ray diffraction, thermogravimetry and N₂-adsorption isotherms techniques. The X-ray patterns of compacted samples show a decrease in the peak intensities. For both pressure-transmitting media, our samples revealed a reduction of the basal d-spacing for the (003) plane when processed at 7.7 GPa. The expected high-pressure-induced amorphization was not observed. Surprisingly, we find high-pressure processing to have a strong influence on the memory effect of the LDH, due essentially to the reduction of the surface area and pore closing. Even when immersed in water, our samples did not recover the LDH structure, when either calcined at 450°C and compacted at 7.7 GPa, or calcined at 700°C and immediately compacted at 2.5 and 7.7 GPa.     

Pathogenic fungi: an unacknowledged risk at coastal resorts? New insights on microbiological sand quality in Portugal

Whilst the potential impact on beach users from microorganisms in water has received considerable attention, there has been relatively little investigation into microbial contaminants in sand. Thirty three beaches across Portugal were analyzed during a five year period (2006-2010) to determine the presence of yeasts, pathogenic fungi, dermatophytes, total coliforms, Escherichia coli and intestinal enterococci in sand.Our results showed that 60.4% of the samples were positive for fungi and that 25.2% were positive for the bacterial parameters. The most frequent fungal species found were Candida sp. and Aspergillus sp., whereas intestinal enterococci were the most frequently isolated bacteria. Positive associations were detected among analyzed parameters and country-regions but none among those parameters and sampling period.Regarding threshold values, we propose 15 cfu/g for yeasts, 17 cfu/g for potential pathogenic fungi, 8 cfu/g for dermatophytes. Eighty four cfu/g for coliforms, 250 cfu/g for E. coli, and 100 cfu/g for intestinal enterococci.     

The impact of ecosystem functional type changes on the La Plata Basin climate

In this paper, the effects of land cover changes on the climate of the La Plata Basin in southern South America are investigated using the Weather and Research Forecasting (WRF) Model configured on a 30/10km two-way interactive nested grid. To assess the regional climate changes resulting from land surface changes, the standard land cover types are replaced by time-varying Ecosystem Functional Types (EFTs), which is a newly devised land-cover classification that characterizes the spatial and interannual variability of surface vegetation dynamics. These variations indicate that natural and anthropogenic activities have caused changes in the surface physical parameters of the basin, such as albedo and roughness length, that contributed to regional climate changes. EFTs are obtained from functional attributes of vegetation computed from properties of the Normalized Difference Vegetation Index (NDVI) to represent patches of the land surface with homogeneous energy and gas exchanges with the atmosphere. Four simulations are conducted, each experimental period ranging from September to November in two contrasting years, 1988 and 1998. The influence of an identical EFT change on the surface heat fluxes, 2-m temperature and humidity, 10-m winds, convective instabilities and large-scale moisture fluxes and precipitation are explored for 1988 (a dry year) and 1998 (a wet year). Results show that the surface and atmospheric climate has a larger response to the same EFT changes in a dry year for 2-m temperature and 10-m wind; the response is larger in a wet year for 2-m water vapor mixing ratio, convective available potential energy, vertically integrated moisture fluxes and surface precipitation. For EFTs with high productivity and a weak seasonal cycle, the nearsurface temperature during the spring of 1988 and 1998 increased by as much as 1℃ in the central and western portions of La Plata Basin. Additionally, for higher productivity EFTs, precipitation differences were generally positive in both dry and wet years, although the patterns are not uniform and exhibit certain patchiness with drier conditions.     

The eruptive history of the Tequila volcanic field, western Mexico: ages, volumes, and relative proportions of lava types

The eruptive history of the Tequila volcanic field (1600 km²) in the western Trans-Mexican Volcanic Belt is based on ⁴⁰Ar/³⁹Ar chronology and volume estimates for eruptive units younger than 1 Ma. Ages are reported for 49 volcanic units, including Volcán Tequila (an andesitic stratovolcano) and peripheral domes, flows, and scoria cones. Volumes of volcanic units 1 Ma were obtained with the aid of field mapping, ortho aerial photographs, digital elevation models (DEMs), and ArcGIS software. Between 1120 and 200 kyrs ago, a bimodal distribution of rhyolite (~35 km³) and high-Ti basalt (~39 km³) dominated the volcanic field. Between 685 and 225 kyrs ago, less than 3 km³ of andesite and dacite erupted from more than 15 isolated vents; these lavas are crystal-poor and show little evidence of storage in an upper crustal chamber. Approximately 200 kyr ago, ~31 km³ of andesite erupted to form the stratocone of Volcán Tequila. The phenocryst assemblage of these lavas suggests storage within a chamber at ~2–3 km depth. After a hiatus of ~110 kyrs, ~15 km³ of andesite erupted along the W and SE flanks of Volcán Tequila at ~90 ka, most likely from a second, discrete magma chamber located at ~5–6 km depth. The youngest volcanic feature (~60 ka) is the small andesitic volcano Cerro Tomasillo (~2 km³). Over the last 1 Myr, a total of 128±22 km³ of lava erupted in the Tequila volcanic field, leading to an average eruption rate of ~0.13 km³/kyr. This volume erupted over ~1600 km², leading to an average lava accumulation rate of ~8 cm/kyr. The relative proportions of lava types are ~22–43% basalt, ~0.4–1% basaltic andesite, ~29–54% andesite, ~2–3% dacite, and ~18–40% rhyolite. On the basis of eruptive sequence, proportions of lava types, phenocryst assemblages, textures, and chemical composition, the lavas do not reflect the differentiation of a single (or only a few) parental liquids in a long-lived magma chamber. The rhyolites are geochemically diverse and were likely formed by episodic partial melting of upper crustal rocks in response to emplacement of basalts. There are no examples of mingled rhyolitic and basaltic magmas. Whatever mechanism is invoked to explain the generation of andesite at the Tequila volcanic field, it must be consistent with a dominantly bimodal distribution of high-Ti basalt and rhyolite for an 800 kyr interval beginning ~1 Ma, which abruptly switched to punctuated bursts of predominantly andesitic volcanism over the last 200 kyrs.Electronic Supplementary Material Supplementary material is available in the online version of this article at Editorial responsility: J. Donnelly-NolanThis revised version was published online in January 2005 with corrections to Tables 1 and 3.An erratum to this article can be found at