Factors governing abundance of hydrolyzable amino acids in the sediments from the N.W. European Continental Margin (47–50°N)

Fifty-six samples representing 6 sediment cores taken along the N.W. European Continental Margin from the shelf, slope and abyssal plain of the Goban Spur and Meriadzek Terrace were quantitatively analysed for total hydrolyzable amino acids (THAA) and clay minerals. In descending order, the five most abundant amino acids making up more than 70% of the total were: aspartic acid, glycine, serine, alanine and glutamic acid. Clay mineral proportions were typical for the N.E. Atlantic, in order of descending abundance: illite, kaolinite, chlorite, smectite and mixed layers.The Meriadzek Terrace area is characterised by fine grain suspension sedimentation with a low pelagic carbonate input and the lowest content of THAA. In contrast, the Goban Spur transect is characterised by much higher carbonate inputs and more vigorous hydrodynamics as judged from granulometry and the high abundance of minerals of shelf and continental origin and a generally higher THAA content. The pelagic portion of THAA deposited at the sea floor is more readily mineralised during early diagenesis than the more ‘refractory', clay mineral-associated continental portion. Along this margin the average mineralization of THAA down to 25 cm in the sediment is about 54%. There is a significant affinity between chlorites and amino acids which we suggest may involve the formation of ionic bonds between the octahedral layers of the clay and the amino acids.     

Experimental investigation on the seismic performance of masonry buildings using shaking table testing

Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of low tensile strength, large mass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second model was built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are also evaluated.     

Coastal vulnerability assessment based on video wave run-up observations at a mesotidal,steep-sloped beach

Coastal imagery obtained from a coastal video monitoring station installed at Faro Beach, S. Portugal, was combined with topographic data from 40 surveys to generate a total of 456 timestack images. The timestack images were processed in an open-access, freely available graphical user interface (GUI) software, developed to extract and process time series of the cross-shore position of the swash extrema. The generated dataset of 2% wave run-up exceedence values R ₂ was used to form empirical formulas, using as input typical hydrodynamic and coastal morphological parameters, generating a best-fit case RMS error of 0.39 m. The R ₂ prediction capacity was improved when the shore-normal wind speed component and/or the tidal elevation η _tide were included in the parameterizations, further reducing the RMS errors to 0.364 m. Introducing the tidal level appeared to allow a more accurate representation of the increased wave energy dissipation during low tides, while the negative trend between R ₂ and the shore-normal wind speed component is probably related to the wind effect on wave breaking. The ratio of the infragravity-to-incident frequency energy contributions to the total swash spectra was in general lower than the ones reported in the literature E _infra/E _inci > 0.8, since low-frequency contributions at the steep, reflective Faro Beach become more significant mainly during storm conditions. An additional parameterization for the total run-up elevation was derived considering only 222 measurements for which η _total,2 exceeded 2 m above MSL and the best-fit case resulted in RMS error of 0.41 m. The equation was applied to predict overwash along Faro Beach for four extreme storm scenarios and the predicted overwash beach sections, corresponded to a percentage of the total length ranging from 36% to 75%.     

Changing poverty distribution in Bolivia: the role of rural–urban migration and urban services

Bolivia is a country with high levels of poverty and inequality among its peoples and regions. For the nation and its urban and rural areas, trends in the social and spatial distribution of poverty (and extreme poverty) are identified from 1976 to 2003 using UBN data with minor support where appropriate from poverty lines. The main survey between 1992 and 2001 uses composite and selected UBN to track detailed poverty change for the country’s nine departments, its ten largest cities and a selection of other smaller urban and rural municipalities. Because of rising background increases in population in the various surveyed administrative units, many instances of relative reductions in poverty are accompanied by rising absolute increases. Marked spatial variations in poverty and development in the country over the last several decades are identified as the main driver for the country’s quickening pace of rural–urban migration. As a result, the paper concludes by assessing two different but closely related views. One investigation tests the notion that because more poor people have been living in Bolivia’s cities than in its rural areas since the mid to late 1990s, rapid rural–urban migration has simply shifted the locus of poverty from the countryside to the cities in a process called, the ‘urbanisation of poverty.’ A second, more challenging, investigation assesses the view that the flow of poor rural people to the better serviced urban areas of Bolivia has actually acted to alleviate national poverty levels.     

Diffuse Emission of CO2 from Showa-Shinzan, Hokkaido, Japan: A Sign of Volcanic Dome Degassing

Two soil CO₂ efflux surveys were carried out in September 1999 and June 2002 to study the spatial distribution of diffuse CO₂ degassing and estimate the total CO₂ output from Showa-Shinzan volcanic dome, Japan. Seventy-six and 81 measurements of CO₂ efflux were performed in 1999 and 2002, respectively, covering most of Showa-Shinzan volcano. Soil CO₂ efflux data showed a wide range of values up to 552 g m^-2 d^-1. Carbon isotope signatures of the soil CO₂ ranged from -0.9‰ to -30.9‰, suggesting a mixing between different carbon reservoirs. Most of the study area showed CO₂ efflux background values during the 1999 and 2002 surveys (B = 8.2 and 4.4 g m^-2 d^-1, respectively). The spatial distribution of CO₂ efflux anomalies for both surveys showed a good correlation with the soil temperature, indicating a similar origin for the extensive soil degassing generated by condensation processes and fluids discharged by the fumarolic system of Showa-Shinzan. The total diffuse CO₂ output of Showa-Shinzan was estimated to be about 14.0–15.6 t d^-1 of CO₂ for an area of 0.53 km².     

Pore Water Characteristics Following a Release of Neat Ethanol onto Pre-existing NAPL

Neat ethanol (75.7 L) was released into the upper capillary zone in a continuous-flow, sand-packed aquifer tank (8.2 m³) with an average seepage velocity of 0.75 m/day. This model aquifer system contained a residual nonaqueous phase liquid (NAPL) that extended from the capillary zone to 10 cm below the water table. Maximum aqueous concentrations of ethanol were 20% v/v in the capillary zone and 0.08% in the saturated zone at 25 and 30 cm downgradient from the emplaced NAPL source, respectively. A bench-scale release experiment was also conducted for a similar size spill (scaled to the plan area). The concentrations of ethanol in ground water for both the bench- and pilot-scale experiments were consistent with advective–dispersive limited mass transfer from the capillary to the saturated zone. Concentrations of monoaromatic hydrocarbons and isooctane increased in the pore water of the capillary zone as a result of both redistribution of residual NAPL (confirmed by visualization) and enhanced hydrocarbon dissolution due to the cosolvent effect exerted by ethanol. In the tank experiment, higher hydrocarbon concentrations in ground water were also attributed to decreased hydrocarbon biodegradation activity caused by preferential microbial utilization of ethanol and the resulting depletion of oxygen. These results infer that spills of highly concentrated ethanol will be largely confined to the capillary zone due to its buoyancy, and ethanol concentrations in near-source zone ground water will be controlled by mass transfer limitations and hydrologic conditions. Furthermore, highly concentrated ethanol releases onto pre-existing NAPL will likely exacerbate impacts to ground water, due to NAPL mobilization and dissolution, and decreased bioattenuation of hydrocarbons.     

Mechanical Behavior of Microbially Induced Calcite Precipitation Cemented Sand

Geotechnical and Geological Engineering - New sustainable ground improvement techniques have been recently required for applications in onshore and offshore geotechnical structures. The...     

A system for large volume aerosol sampling in the stratosphere using electrostatic precipitation

Summary An instrumental system for securing aerosol samples in the stratosphere by electrostatic precipitation has been developed. The system is designed to be balloon borne to altitudes between 30 km and 45 km and to collect with high efficiency the aerosol content of the stratosphere at these altitudes. Volumetric sampling rates of one meter³ sec^–1 ambient air are obtained with the sampling configuration with collection efficiency in excess of 95 percent for particles between .01 microns (mmd) and 2 microns (mmd).Specially developed associated instrumentation for altitude and air flow measurement points to an important versatility in the application of gas discharges for low-pressure (or high altitude) altimetry and anemometry over a very wide range of air densities and tempertures.The theory, operation, and performance of the aerosol sampling system and associated subsytems are described. Certain new observations of low-density corona physics phenomena are reported and potential applications to other areas of research and technology are indicated.

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Zusammenfassung Es wurde ein Instrument entwickelt, mit dem man Aerosolproben aus der Stratosphäre durch elektrostatischen Niederschlag erhalten kann. Das System wird von einem Ballon in Höhen zwischen 30 und 45 km getragen und sammelt mit hoher Wirksamkeit Proben des Aerosolgehalts in diesen Höhen. Mit dem Instrument wird eine Sammelgeschwindigkeit von 1 m³/sek erreicht bei einer Sammelwirksamkeit von mehr als 95% für Partikel von Größen zwischen 0,01 und 2 Mikron.Besonders entwickelte angeschlossene Instrumente zur Messung der Höhe und der Luftströmungen zeigen die wesentliche Vielseitigkeit der Anwendung von Gasentladungen für die Höhenmessung und Windmessung bei niedrigem Druck (oder in großen Höhen) in einem großen Bereich der Luftdichte und der Temperatur.Es werden die Theorie, die Arbeitsweise und die Ausführung des Aerosolprobeninstrumentes und der angeschlossenen Hilfssysteme beschrieben. Es wird über einige neue Beobachtungen aus dem Bereich der Phänomene der Gasentladungen bei niedriger Dichte berichtet und neue mögliche Anwendungen in anderen Zweigen der Forschung und Technologie werden angegeben.

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Résumé On a construit un instrument au moyen duquel on peut obtenir des échantillons d'aérosole stratosphérique par précipitation électrostatique. Le système est emporté par un ballon à des altitudes de 30 à 45 km et rassemble avec efficacité des echantillons du contenu de l'aérosole à ces altitudes. Avec cet appareil, on obtient une vitesse de prise de 1 m³/sec avec une efficacité de plus de 95% pour les particules comprises entre 0,01 et 2 microns.Des appareils spéciaux annexes permettent de mesurer la hauteur et les courants d'air. Ils démontrent les possibilités multiples de l'utilisation de la décharge dans un gaz pour la mesure de l'altitude et des vents par pression très faible (ou à très haute altitude) dans un domaine étendu tant de la densité de l'air que de la température.On décrit dans ce mémoire la théorie, le mode de travail et l'exécution de cet instrument de prise d'échantillons d'aérosoles ainsi que des systèmes auxiliaires annexes. On rapporte sur quelques nouvelles observations faites dans le domaine des phénomènes connexes à la décharge dans un gaz par faible densité. On indique en outre de nouvelles possibilités d'utilisation du système dans d'autres branches de la recherche ou de la technologie.

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With 16 Figures

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This work has been supported by the Division of Biology and Medicine, U. S. Atomic Energy Commission, under contract at (30-1)-2363 with Del Electronics.     

A Monte Carlo Model Of The Nocturnal Surface Temperatures In Urban Canyons

A model for the urban canyon is formulated for meteorologicalconditions of weak winds at night time. Thermal radiation, conductivity and convection are simulated by means of the Monte Carlo method. These are the main physical processesof energy transfer that give rise to the characteristic temperaturedistribution in these systems. The model has been satisfactory tested under ideal conditions for which analytical solutions exist.The predictions of the model under morerealistic conditions accurately reproduce the observationalresults. A strong temperature gradient across streets, with the canyon corners up to 4 °C warmer than the canyon centre, is found for the deepest canyons. This theoretical predictionhas been successfully verified with measurementstaken in a number of streets of the city of Granada in Spain.