Optimum selection of design parameters for transportation of offshore structures

A probabilistic framework is presented to select the design significant wave height and design transverse rotation for typical barges used in the Gulf of Mexico for marine transportation of structural elements and/or systems. The selection of design transverse rotation is based on optimization procedure that trade-off between the performance of the barge subjected to a meteorological-oceanographic (metocean) hazard along the route and losses by structural damage. For this purpose probabilistic models to estimate the metocean hazard for marine transportation are shown. Afterwards, the design rotation is linked to the design of significant wave height and to the return period associated with such wave conditions. The formulation is applied to an offshore transportation route in the Gulf of Mexico.     

Giant gas bubbles in a rheomorphic vent fill at the Las Cañadas caldera,Tenerife (Canary Islands)

During rheomorphism subsequent to fallout deposition, a portion of the densely welded fallout of the La Grieta Member flowed back into the vent from where it was erupted, while the rest of it flowed down the outer slopes of the Las Cañadas caldera in Tenerife. The welded fallout and conduit-vent structure are physically connected and constitute a rare example of this type of deposits rooted to its feeder conduit and exposed in the caldera wall. The lower part of the vent-filling rheomorphic rocks shows gas bubbles and cavities that increase in size (up to 4 m) down vent. Bubbles are deformed against other bubbles, against the steep vent walls, flattened parallel to the flow foliation planes, and elongated parallel to the flow lineation and flow fold axes. The preservation of such giant bubbles, rather than their formation, seems to be a pretty unique feature of the phonolitic products investigated here and it is likely the result of the combination of factors that acted to preserve, in the surrounding of the glass transition interval, the sealing and the late stage cooling of a pressurized system. In addition, strain drop at the base of the vent-filling rheomorphic flow caused by flow stopping against vertical vent walls may have promoted rapid gas exsolution and the formation of large bubbles.     

Remote Sensing of Three-dimensional Winds with Elastic Lidar: Explanation of Maximum Cross-correlation Method

Maximum cross-correlation provides a method toremotely de-ter-mine high-lyre-solved three-dimensional fields of horizontalwinds with e-las-tic li-darthrough-out large volumes of the planetaryboundary layer (PBL). This paperdetails the technique and shows comparisonsbetween elastic lidar winds, remotelysensed laser Doppler velocimeter (LDV) windprofiles, and radiosonde winds.Radiosonde wind data were acquired at Barcelona,Spain, during the BarcelonaAir-Quality Initiative (1992), and the LDVwind data were acquired at SunlandPark, New Mexico during the 1994 Border AreaAir-Quality Study. Comparisonsshow good agreement between the differentinstruments, and demonstrate the methoduseful for air pollution management at thelocal/regional scale. Elastic lidar windscould thus offer insight into aerosol andpollution transport within the PBL. Lidarwind fields might also be used to nudge orimprove initialization and evaluation ofatmospheric meteorological models.     

Circulatory Patterns of Air Pollutants within the Barcelona Air Basin in a Summertime situation: Lidar and Numerical Approaches

This work examines circulatory patterns of airpollutants in the area of Barcelona (Spain), a regionwith strong coastal and orographic influences. Thiswas achieved through exploitation ofelastic-backscatter lidar data and by numericalsimulation of the atmosphere with a meteorologicalmesoscale model (MEMO). Lidar data were acquired inJuly 1992 during a collaborative campaign between LosAlamos National Laboratory (LANL) and the PolytechnicUniversity of Catalonia (UPC). The lidar providedinformation about the distribution of aerosols and theprevailing winds, determined by application of amaximum cross-correlation algorithm toelastic-backscatter lidar data. Lidar winds are usedto evaluate high altitude winds simulated by themodel. This study showed that circulatory patterns inBarcelona are correlated with daytime convectivevertical mixing, sea-breeze circulations, and verticalforcing caused by mountain thermal and mechanicaleffects.     

Spatial and temporal distribution of dissolved/dispersed aromatic hydrocarbons in seawater in the area affected by the Prestige oil spill

Seawater samples collected at three depths from 68 stations along the Northern Spanish coast were analysed for dissolved/dispersed petroleum aromatic hydrocarbons by UV-fluorescence and for 25 individual compounds by GC-MS. Sampling was performed in December 2002, just after the Prestige oil spill, and in February-March and September 2003. Higher concentrations of total aromatic hydrocarbons were found at all depths in the samples collected during December 2002 off the Galicia coast, with levels ranging between 0.19 and 28.8 microg/L eq. oil (0.1-4.8 microg/L chrysene eq.). These values decreased in the following cruises, till <0.05-2.86 microg/L oil eq. (av. 0.23 microg/L chrysene eq.) in September 2003, possibly representing the background levels for the region. However, in the Cantabrian coast they were still high at the surface in the March cruise, probably by the late arrival of the fuel-oil to this area. Some coastal hot spots were also identified, with values up to 29.2 microg/L fuel-oil eq., close to river mouths and urban areas. The individual PAH distributions in the December 2002 sampling off-Galicia were dominated by alkyl-naphthalene derivatives, consistently with the pattern distribution shown by the fuel-oil water accommodated fraction. The higher concentrations were found in the subsurface samples along the Costa da Morte, the area most heavily affected by the spill (av. 0.46 microg/L Sigma16 PAHs). The rest of the samples collected in other areas exhibited lower concentrations and a more even distribution of 2-4 ring PAHs, that ranged from 0.09 to 0.37 microg/L (av. 0.15 microg/L Sigma16 PAHs), with decreasing trends offshore and downward the water column. In September 2003, the values were rather uniform, averaging 0.09 microg/L (Sigma16 PAHs).     

Applying GPR-amplitude wave maps and Am-scans as a semi-quantitative approach to the internal structure of sediments

In this work we analyse the applicability of amplitude grid maps to the routine of geological surveys by means of GPR (ground penetrating radar). Although amplitude grid maps have been commonly used in archaeological surveys, their use in geological prospecting (including the detection of voids and determination of the internal geometry of sedimentary bodies) is not widespread. The direct analysis of GPR-profiles permits the analysis of geometrical features and other qualitative aspects that can be related to changes in EM properties. Aspects such as changes in the density of the banded disposition in radargrams, loss of reflector definition or higher scattering in particular zones of the profiles can give useful, though non-quantitative, information. The GPR wave-amplitude is a qualitative measurement of magnetic properties that can be processed as a semi-quantitative layout. The main differences observed in changing wave amplitude are related to the surveyed materials and their geometry. These changes produce variations in the relative wave amplitude or vertical wave-phase changes related to differences in the propagation velocity, the attenuation factor, the reflectivity and the geometry of the materials. Maps based on the lateral correlation between profiles (C-scans) or the lateral correlation of wave amplitudes along the same profile (as a tomography or Am-scans) permit the analysis of these changes. Variations in amplitude grid maps or Am-scans are related to (i) geometrical changes of surveyed materials, (ii) changes in the dielectric constant, and (iii) changes in the potential penetration depth (higher attenuation in particular zones of a profile) than can be correlated to the type, state or clay content of subsoil materials. Direct analysis of exposures helps to constrain interpretation using the geometrical features in radargrams resulting from the geological structure. In the same way, analysis of geometrical features in radargrams, together with time-slices of C-scans, can be used to determine the areal distribution of changes in the subsoil and approach the changes in EM properties. An example with parallel profiles and different devices, constrained by means a broadband multifrequency EM survey is shown.     

Kobo 1 and L'Abri aux Vaches (Mali,West Africa): Two case studies for the optical dating of bioturbated sediments

The purpose of the study was to provide further chronological data for the microlithic assemblages in the region of the Dogon Country (Mali). In two sites, Kobo 1 and L'Abri aux Vaches, the absence of any characteristic material could not help in concluding whether the microliths were of Pleistocene or Holocene age. Radiocarbon dating failed because the analysed charcoals appeared to have been introduced following recent bioturbation. These were visible in the archaeological sections and therefore, an attempt at dating with single-grain optically stimulated luminescence was made. After discussing the appropriate way of applying the Finite Mixture Model, we are able to conclude that the sediments containing the microliths from L'Abri aux Vaches were deposited during the beginning and the middle of the Holocene period (13.5 ± 1.0 and 5.9 ± 0.4 ka). For Kobo 1, the analysis reveals extensive bioturbation, precluding the obtaining of any reliable result.     

Mapping subsurface karst features with GPR: results and limitations

Ground penetrating radar (GPR) has been applied, with relative success, to locate paleo-collapses and cavities and to detect and characterise karst. One of its main advantages is that, while the penetration depth is limited to several tens of meters or even just several meters, the obtained resolution can be in the scale of centimeters. In this paper, we illustrate the applicability of GPR prospecting to the study of alluvial karst and the structures associated with subsidence areas. GPR radargrams obtained with two central frequency antennas (50 and 100 MHz) are balanced against direct observation of geological features of collapse structures in vertical exposures of gravel quarries. GPR-surveys offer the possibility of obtaining nearly continuous vertical cross-sections of the subsoil, and integration of data within a 3D frame. However, the study of the internal structure of the subsoil by means of the GPR-profiles has been usually neglected. In this work, we show that some hints about the evolution of individual dolines can be established from the study of the geometry of the sedimentary filling by means of GPR. The obtained results indicate that GPR allows to characterise the structures associated with karst features and can therefore be useful evaluating hazard susceptibility in doline fields, because: (1) when no surface evidences exists, it permits the detection of karst hazards in the subsoil, and (2) when surficial evidences of karst activity are present, it permits the characterisation of processes associated with subsidence.     

Effects of weather types on hospital admissions for respiratory diseases in Castilla-La Mancha,Spain

The aim of this study is to evaluate the relationship between the risk of hospital admission for respiratory diseases (RD) and the daily weather types during the period 2000-2006. A synoptic climatological approach is used to investigate links between air-mass types (weather situations) and all respiratory hospital admissions in the Castilla-La Mancha (CLM) area in Spain. This afforded the main circulation weather types (CWTs) for the winter and spring periods (since respiratory hospital admissions reached their maximum during these seasons) and the frequency distributions of these types were analyzed. A summary of the main characteristics of the hospital admission series and their distribution over the seven years studied, together with the frequency distributions of the admissions classified by sex and ages, for season, month and for each day of the week, is reported. In addition, a comparison between air-mass classification and hospital admissions is made using an admission index (AI). The results reveal different responses of respiratory admission rates to the eight air-mass types identified in winter and in spring. In winter, three air massess southwesterly (SW), anti-cyclonic (A) and hybrid anti-cyclonic southwesterly (HASW), are associated with values 1.5 times higher than the respective average admission rates, while in spring no significant differences are seen.     

Responses to salt stress in the halophyte Plantago crassifolia (Plantaginaceae)

General responses to salt stress have been investigated in the halophyte Plantago crassifolia. Seed germination was strongly inhibited by NaCl, although seed viability and germination capacity were not affected by salt pre-treatments. A concentration-dependent inhibition of plant growth was observed in the presence of NaCl, which was accompanied by the accumulation of Na⁺ ions in the leaves, as determined by cation exchange HPLC. A 20-fold increase of proline content in leaves was observed when plants were treated with 500 m NaCl, suggesting a protective role against high salinity stress for this amino acid, whose possible mechanism of action is discussed.