Comparison of stabiliser functions for surface NMR inversions

Surface nuclear magnetic resonance is a geophysical technique providing non-invasive aquifer characterization. Two approaches are commonly used to invert surface nuclear magnetic resonance data: (1) inversions involving many depth layers of fixed thickness and (2) few-layer inversions without predetermined layer thicknesses. The advantage of the many-layer approach is that it requires little a priori knowledge. However, the many-layer inversion is extremely ill-posed and regularisation must be used to produce a reliable result. For optimal performance, the selected regularisation scheme must reflect all available a priori information. The standard regularisation scheme for many-layer surface nuclear magnetic resonance inversions employs an L-2 smoothness stabiliser, which results in subsurface models with smoothly varying parameters. Such a stabiliser struggles to reproduce sharp contrasts in subsurface properties, like those present in a layered subsurface (a common near-surface hydrogeological environment). To investigate if alternative stabilisers can be used to improve the performance of the many-layer inversion in layered environments, the performance of the standard smoothness stabiliser is compared against two alternative stabilisers: (1) a stabiliser employing the L-1-norm and (2) a minimum gradient support stabiliser. Synthetic results are presented to compare the performance of the many-layer inversion for different stabiliser functions. The minimum gradient support stabiliser is observed to improve the performance of the many-layer inversion for a layered subsurface, being able to reproduce both smooth and sharp vertical variations of the model parameters. Implementation of the alternative stabilisers into existing surface nuclear magnetic resonance inversion software is straightforward and requires little modification to existing codes

What's in a Name? Shifting Identities of Traditional Organized Crime in Canada in the Transnational Fight against the Calabrian ‘Ndrangheta

The Italian antimafia authorities have warned Canadian law enforcement about the risks and the growing concerns for the infiltration of clans of the Calabrian mafia, known as ‘ndrangheta, in Eastern Canada. The alarm linked to the rise of the ‘ndrangheta challenges the paradigms of traditional organized crime in Canada, because the ‘ndrangheta is presented as traditional but also innovative and more pervasive than other mafia-type groups. Through access to confidential investigations and interviews to key specialist law enforcement teams in Toronto and Montreal, this article investigates today's institutional perception of mafia – the ‘ndrangheta in particular – in Canada when compared to Italian conceptualizations. I will argue that the changes in narratives in Canada can be read in relation to changes in the Italian identity in the country, moving towards regionalization and specialist knowledge of ethnic differences

Estimating T2 from surface NMR FID data using a forward model based on the full-Bloch equation

An integral component of the surface nuclear magnetic resonance forward model involves predicting the magnitude of the transverse magnetization following excitation. To predict the transverse magnetization, the Bloch equation must be solved. Traditional surface NMR forward models solve a simplified version of the Bloch equation where the relaxation terms are neglected. A shortcoming of this approach is that it can struggle to accurately describe the impact of relaxation during pulse effects. To address this concern, an alternative forward model based on solution of the full-Bloch equation is proposed. The advantage of the proposed scheme is that it implicitly accounts for relaxation during pulse effects, increases the flexibility to implement alternative parametrizations of the inverse model, and can readily describe an arbitrary excitation protocol given that it no longer requires closed form expressions of the transverse magnetizations. To demonstrate the potential of the updated forward modelling scheme, a novel approach for the inversion of complex-valued free-induction decay (FID) data is presented. The inverse model is reparametrized in order to produce depth profiles of the water content, T2 17 and T2. This approach has great potential to enhance the ability of FID measurements to provide insights into pore size and permeability as it can provide direct sensitivity to T2. In contrast, traditional approaches that employ a forward model based on the simplified Bloch equation and estimate only T2 17 are plagued by uncertainty surrounding the link between T2 17 and pore size/permeability. Synthetic and field results are presented to demonstrate the feasibility of the proposed forward model and FID inversion framework

Smartphone-based bridge monitoring through vehicle-bridge interaction: analysis and experimental assessment

In this study, the results of a vast experimental campaign on the applicability of a smartphone-based technique for bridge monitoring are presented. Specifically, the vehicle-bridge interaction (VBI)-based approach is exploited as a cost-effective means to estimate the natural frequencies of bridges, with the final aim of possibly developing low-cost and diffused infrastructure monitoring system. The analysis is performed using a common hybrid vehicle, fully equipped with classical piezoelectric accelerometers and a smartphone MEMS accelerometer, to record its vertical accelerations while passing over the bridge. In this regard, the experimental campaign is carried out considering the vehicle moving with a constant velocity on a bridge in the city of Palermo (Italy). Appropriate identification procedures are then employed to determine the modal data of the bridge from the recorded accelerations. Further, comparisons with the results of a standard Operational Modal Analysis procedure, using accelerometers directly mounted on the structure, are presented. Experimental VBI-based analyses are performed also considering the effect of several different vehicle velocities. Further, the applicability of smartphone-based sensor data is investigated, exploiting the possibility of using up-to-date smartphone accelerometers for recording the vehicle accelerations. In this regard, comparison between piezoelectric accelerometers and MEMS ones is performed to assess the reliability of these sensors for the determination of bridge modal properties

Spectral time-domain induced polarisation and magnetic surveying - An efficient tool for characterisation of solid waste deposits in developing countries

Time-domain induced polarisation and magnetic data were acquired to map and characterise the decommissioned and un-engineered municipal solid waste disposal site of the Kwame Nkrumah University of Science and Technology, located in the Kumasi Metropolis of Ghana. In this survey. 13 induced polarisation profiles 500-800 m long and 26 magnetic profiles 400-800 m long were acquired. In addition, two boreholes were drilled to help in the interpretation of the geophysical data. The study was carried out with the aim of determining the risk posed by the waste deposit to the quality of the soil and the ground water system, which is the main potable water supply for the Secondary School, the University Teaching Hospital and the Veterinary School, situated within the catchment area of the site. Full-decay 2-D time-domain induced polarisation inversions in terms of Cole-Cole parameters were used for interpreting the induced polarisation data. The chargeability, resistivity and normalised chargeability distributions, together with the magnetic results, aided in a full characterisation of the site geology, the waste and the associated pollution plume. In particular, clear contrasts in resistivity and the polarisation parameters were found between the saprolite layer and the granitic bedrock, which are the main lithological units of the area. Furthermore, it was found that the Kwame Nkrumah University of Science and Technology waste deposit is characterised by a low-chargeability and low-resistivity signature and that the low-resistivity area spreads out from the waste deposit into the permeable saprolite layer, indicating the presence of a leachate plume. A fracture zone in the granitic bedrock beneath the waste deposit, which is a potential conduit for leachate contamination of the ground water system, was also identified. The study thus provides the information needed for assessing the future impact of the waste on the water quality in the area and for designing risk-mitigation actions

Business, finance and organized crime: proposing a risk-based approach for governance in a law and economics perspective (the “Vigna Code”)

La criminalità organizzata contemporanea trae vantaggi dall’integrazione e dalla globalizzazione delle attività industriali, commerciali e finanziarie, utilizzando il medesimo network impiegato per le transazioni lecite. Le organizzazioni criminali, allo scopo di espandere i propri interessi, cercano di utilizzare banche ed aziende al di sopra di ogni sospetto, in modo da conseguire nuovi profitti e riciclare il denaro sporco. Il rischio di inquinamento del mercato è dunque crescente. Lo scopo del paper è di proporre un codice antimafia (il c.d. “Codice Vigna”) in materia di regole di governo societario, sviluppando un approccio interdisciplinare basato sul fattore di rischio di inquinamento illecito delle imprese, allo scopo di introdurre regole che ostacolino e prevengano l’espansione della criminalità organizzat

Riesce: an Hypertextual Tool for Browsing Information Produced in the Building Sector by PFEd

The structure of a set of documents allow for navigation inside single texts. Yet it is often also an obstacle to comparability between different parts and concepts. Even document formatting is only a partial answer to the problem, since it fails to develop the matter of relationships between enunciation and results. It was need to retrieve information about the scientific findings made by Research Units (Operating Units) during the first three year period of the “Progetto Finalizzato Ediliziai (PFEd) for assessment and transfer purposes which led us to design and develop a system to facilitate the retrieval of the relevant information. We chose the building sector for this application because of its relative lack of previous experience of this type, the variety and complexity of documentation available and, last but not least, the general underestimation of research topics and results vis--vis the development of the sector. By making the suggestion and information inherent in its findings more available, in terms of method and ambit, as well as more explicit, the research has already achieved a significant result. In view of the prototype character of the experiment, the information will probably be adopted to produce an hypertext on the final results.

Psychological impact of thrombosis in the young.

Thrombosis is rare in the young, but can cause severe psychological distress that influences the quality of life and the coping capacities of these patients. This study was meant to increase the understanding of self-perception, social and family functioning and ways of coping with the disease in young patients after an episode of thrombosis. Seven questionnaires spanning social and family functioning and ways of coping with disease were completed by 50 patients 6445 years of age after a first episode of venous or arterial thrombosis. Data were compared with those of 39 healthy individuals with similar age, sex and level of education. Compared to healthy controls, young patients with thrombosis had lower self-esteem, showed higher impairment in social activities and in familial relationships, and used more frequently coping strategies. Most patients used all coping strategies, preferring the more active ones, but more patients than controls used the passive ones, particularly "avoidance" and "religiosity". A correlation was found between the frequency of use of passive or negative coping strategies and some of the psychological, social and familial dimensions that scored more negatively. Greater psychological impairment and differences in coping styles were found in women compared with men and in individuals <34 years compared with those 6534 years. Young individuals with thrombosis develop psychological changes that influence their behaviour, quality of life and coping. This is particularly evident in women and in young patients. Physicians dealing with thrombosis should be aware of this situation and offer psychological suppor