The potential of ground gravity measurements to validate GRACE data

New satellite missions are returning high precision, time-varying, satellite measurements of the Earth’s gravity field. The GRACE mission is now in its calibration/- validation phase and first results of the gravity field solutions are imminent. We consider here the possibility of external validation using data from the superconducting gravimeters in the European sub-array of the Global Geodynamics Project (GGP) as ‘ground truth’ for comparison with GRACE. This is a pilot study in which we use 14 months of 1-hour data from the beginning of GGP (1 July 1997) to 30 August 1998, when the Potsdam instrument was relocated to South Africa. There are 7 stations clustered in west central Europe, and one station, Metsahovi in Finland. We remove local tides, polar motion, local and global air pressure, and instrument drift and then decimate to 6-hour samples. We see large variations in the time series of 5–10<i>µ</i>gal between even some neighboring stations, but there are also common features that correlate well over the 427-day period. The 8 stations are used to interpolate a minimum curvature (gridded) surface that extends over the geographical region. This surface shows time and spatial coherency at the level of 2– 4<i>µ</i>gal over the first half of the data and 1–2<i>µ</i>gal over the latter half. The mean value of the surface clearly shows a rise in European gravity of about 3µgal over the first 150 days and a fairly constant value for the rest of the data. The accuracy of this mean is estimated at 1<i>µ</i>gal, which compares favorably with GRACE predictions for wavelengths of 500 km or less. Preliminary studies of hydrology loading over Western Europe shows the difficulty of correlating the local hydrology, which can be highly variable, with large-scale gravity variations.<br><br><b>Key words. </b>GRACE, satellite gravity, superconducting gravimeter, GGP, ground trut

A web application prototype for the multiscale modelling of seismic input

A web application prototype is described, aimed at the generation of synthetic seismograms for user-defined earthquake models. The web application graphical user interface hides the complexity of the underlying computational engine, which is the outcome of the continuous evolution of sophisticated computer codes, some of which saw the light back in the middle '80s. With the web application, even the non-experts can produce ground shaking scenarios at the local or regional scale in very short times, depending on the complexity of the adopted source and medium models, without the need of a deep knowledge of the physics of the earthquake phenomenon. Actually, it may even allow neophytes to get some basic education in the field of seismology and seismic engineering, due to the simplified intuitive experimental approach to the matter. One of the most powerful features made available to the users is indeed the capability of executing quick parametric tests in near real-time, to explore the relations between each model's parameter and the resulting ground motion scenario. The synthetic seismograms generated through the web application can be used by civil engineers for the design of new seismo-resistant structures, or to analyse the performance of the existing ones under seismic load.Comment: 23 pages, 13 figure

Production of biogas - a manner of manufacturing

Advertising is commonly criticised for being pervasive, offensive, manipulative, harmful and irresponsible. This thesis focuses on the subjective criticisms and complex issues related to taste, decency, morality and offence, particularly as applied to, and understood within, the public and non-profit contexts. It is positioned at the intersection of marketing communications, marketing ethics, and social and non-profit marketing and explores how shocking, offensive and/or controversial (SOC) advertising appeals are interpreted, regulated and contested, by divergent groups of people. The approach taken is inspired by stakeholder theory and its focus on ethical decision-making for the betterment of all stakeholders. A mixed methods research design was adopted, resulting in three studies and these are presented as three discrete articles. Article I maps the field of existing research into SOC advertising and identifies gaps in our knowledge by means of a systematic literature review. It offers a critical appraisal of the field by highlighting definitional tensions, limited interdisciplinary work and an overdependence on student samples, on quantitative analysis and on non-longitudinal methodologies. It then proposes a series of remedies to these shortcomings. The second and third papers continue this reparative work by conceptualising and analysing actual SOC advertising interpretations and contestations. Article II explores the interpretations and experiences of SOC advertising within the regulatory context by analysing evidence from complainants, advertisers and regulatory bodies. It then proposes and develops an interpretation of the implicit power dynamics through which their contradictory interests overlap. The methodology underpinning this chapter combines a thematic content analysis of a substantial archive of complaints submitted to the Advertising Standards Authority (ASA) with an interpretation of case adjudication reports influenced by the work of Michel Foucault. The findings suggest that the regulation of SOC advertising prioritises the interests of firms and advertisers by relegating the role of complainant to that of merely registering complaints. The focus of Article III moves from the regulatory framework to the complained-about advertisements themselves. It provides an innovative theoretical and methodological approach to analysing SOC advertisements, rooted in the classic Aristotelian notion of rhetorical appeals and figuration, by developing and analysing a carefully selected example in detail. The analysis reveals an implicit NFP sector-specific appeal to ethos and the importance of a complex appeal to pathos. Each of the papers offers a different level of analysis of the often-contradictory viewpoints represented by stakeholder groups involved in, or affected by, the use of SOC advertising tactics. These viewpoints include academics, general consumers, the vocal minority of complainants, the advertisers including the non-profit and public organisations and the advertising creatives, and the advertising regulator. Taken together, the papers amount to a thesis that makes an important contribution to debates about the appropriateness, ethics, and application of SOC themes, formats and imagery in social and non-profit advertising. By exploring the regulatory processes of the ASA, an exemplary advertising self-regulatory body, it further contributes to the discourse on self-regulatory practices and highlights an NFP sector-specific consequentialist approach that appears to stifle the voice of the offended complainant. On a practical level, this work has implications for advertising practitioners and advertising regulators who are involved in producing and regulating advertising that uses SOC tactics

Complex conductivity of soils

The complex conductivity of soils remains poorly known despite the growing importance of this method in hydrogeophysics. In order to fill this gap of knowledge, we investigate the complex conductivity of 71 soils samples (including four peat samples) and one clean sand in the frequency range 0.1 Hz to 45 kHz. The soil samples are saturated with six different NaCl brines with conductivities (0.031, 0.53, 1.15, 5.7, 14.7, and 22 S m21, NaCl, 258C) in order to determine their intrinsic formation factor and surface conductivity. This data set is used to test the predictions of the dynamic Stern polarization model of porous media in terms of relationship between the quadrature conductivity and the surface conductivity. We also investigate the relationship between the normalized chargeability (the difference of in-phase conductivity between two frequencies) and the quadrature conductivity at the geometric mean frequency. This data set confirms the relationships between the surface conductivity, the quadrature conductivity, and the normalized chargeability. The normalized chargeability depends linearly on the cation exchange capacity and specific surface area while the chargeability shows no dependence on these parameters. These new data and the dynamic Stern layer polarization model are observed to be mutually consistent. Traditionally, in hydrogeophysics, surface conductivity is neglected in the analysis of resistivity data. The relationships we have developed can be used in field conditions to avoid neglecting surface conductivity in the interpretation of DC resistivity tomograms. We also investigate the effects of temperature and saturation and, here again, the dynamic Stern layer predictions and the experimental observations are mutually consistent

The Ore-Dressing Grindstone Called a ‘Quimbalete’: a Mechanics-Based Approach

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