Hydrobiogeochemical Interactions along “Flow Tubes” Controls: Watershed Scale Contaminant Flow and Transformation at the Oak Ridge IFRC

Geochemical,spectrographic, microbiological and hydrogeologic studies at the ORIFRC site indicate that groundwater transport in structured media may behave as a system of parallel flow tubes. These tubes are preferred flowpaths that enable contaminant transport parallel to bedding planes (strike) over distances of 1000s of meters. A significant flux of groundwater is focused within an interval defined by the interface between the competent bedrock and overlying highly-weathered saprolite, commonly referred to as the"transition zone." Characteristics of this transition zone are dense fractures and the relative absence of weathering products (e.g. clays)results in a significantly higher permeability compared to both the overlying clay-saprolite and underlying bedrock. Several stratabound low seismic velocity zones located below the transition zone were identified during geophysics studies and were also determined to be fractured high permeability preferred contaminant transport pathways during subsequent drilling activities. XANES analysis of precipitates collected from these deeper flow zones indicate 95% or more of the U deposited is U(VI). Linear combination fitting of the EXAFS data shows that precipitates are ~51±5% U(VI)-carbonate-like phase (e.g., liebigite) and ~49±5% U(VI) associated with an iron oxide phase; inclusion of a third component in the fit suggests that up to 15% of the U(VI) may be associated with a phosphate phase or OH- phase (e.g.,schoepite). Although precipitates with similar U(VI)-carbonate and/or phosphate associations were identified in the transition zone pathways,there were also U(VI) complexes adsorbed to mineral surfaces that would tend to be more readily mobilized. Groundwater in the different flow tubes has been determined to consist of different water quality types that vary with the solid phase encountered (e.g., clays, carbonates, clastics) as contaminants migrate along the flow paths. This lateral and vertical variability in geochemistry, particularly pH, has a significant impact on microbiological community composition and activity. Ribosomal RNA gene analyses coupled with physiological and genomic analyses suggest that bacteria from the genus Rhodanobacter(a diverse population of denitrifiers that are moderately acid tolerant) have a high relative abundance in the acidic source zone at the ORIFRC site.Watershed-scale analysis across different flow paths/tubes revealed strong negative correlation between pH and the absolute and relative abundance of Rhodanobacter. Recent studies also confirmed that the ORIFRC site hosts a diverse fungal community, with significant differences observed between acidic (pH <5) and circumneutral (>5) wells. The lack of nitrous oxide reduction capability in fungi, and the detection of denitrification potential in slurry microcosms suggest that fungi may have aheretofore under appreciated role in biogeochemical transformations, with implications forsite remediation and greenhouse gas emissions. Further research is needed to determine if these organisms can influence U(VI) mobility either directly through immobilization or indirectly through the depletion of nitrate.In conclusion, additional studies are required to quantify the processes (e.g., solid phase reactions, recharge, diffusion, microbial interactions) that are occurring along the groundwater flow tubes identified at the ORIFRC so predictive models can be parameterized and used to assess long-term contaminant fate and transport and remedial options.

Quantitative Analysis of Fault and Fracture Systems and their Impact on Groundwater Flow in Irish Bedrock Aquifers

Fault and fracture systems are the most important store and pathway for groundwater in Ireland’s bedrock aquifers, either directly as conductive flow structures, or indirectly as the locus for the development of dolomitised limestone and karst. This article presents the preliminary results of a study involving the quantitative analysis of fault and fracture systems in the broad range of Irish bedrock types and a consideration of their impact on groundwater flow. The principal aims of the project are to develop generic conceptual models for different fault/fracture systems in different lithologies and at different depths, and to link them to observed groundwater behaviour. Here we briefly describe the geometrical characteristics of the main post-Devonian fault/fracture systems controlling groundwater flow from field observations at outcrops, quarries and mines. The structures range from Lower Carboniferous normal faults through to Variscan-related faults and veins, with the most recent structures including Tertiary strike-slip faults and ubiquitous uplift-related joint systems. The geometrical characteristics of different fault/fracture systems combined with observations of groundwater behaviour in both quarry and mine localities, can be linked to general flow and transport conceptualisations of Irish fractured bedrock. Most importantly they also provide a basis for relating groundwater flow to particular fault/fracture systems and their expression with depth and within different lithological sequences, as well as their regional variability.

ELM-induced transient tungsten melting in the JET divertor

The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER.

Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of I-P = 3.0 MA/B-T = 2.9 T H-mode pulses with an input power of P-IN = 23 MW, a stored energy of similar to 6 MJ and regular type I ELMs at Delta W-ELM = 0.3 MJ and f(ELM) similar to 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within similar to 1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (delta W similar to 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957-64).

Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (similar to 80 mu m) were released. Almost 1 mm (similar to 6 mm(3)) of W was moved by similar to 150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j x B forces. The evaporation rate determined from spectroscopy is 100 times less than expected from steady state melting and is thus consistent only with transient melting during the individual ELMs. Analysis of IR data and spectroscopy together with modelling using the MEMOS code Bazylev et al 2009 J. Nucl. Mater. 390-391 810-13 point to transient melting as the main process. 3D MEMOS simulations on the consequences of multiple ELMs on damage of tungsten castellated armour have been performed.

These experiments provide the first experimental evidence for the absence of significant melt splashing at transient events resembling mitigated ELMs on ITER and establish a key experimental benchmark for the MEMOS code.

Striking a Balance:Christianity and the Challenges of Long-Term Human Security in Zimbabwe

African evangelical/Pentecostal/charismatic (EPC) Christians-previously dismissed by scholars as apolitical-are becoming increasingly active socially and politically. This chapter presents a case study of an EPC congregation in Harare. It demonstrates how the congregation provides short-term human security by responding to the needs of the poor, while at the same time creating space where people can develop the "self-expression values" necessary for long-term human security. The case study also demonstrates that even under authoritarian states, religious actors can actively choose to balance the immediate demands of short-term human security with the sometimes competing demands of long-term human security. Policymakers can benefit from a greater understanding of how religious actors strike this balance and from a greater appreciation of the variability, flexibility, and religious resources of EPC Christians in such contexts.

Cell Coverage Optimization for the Multicell Massive MIMO Uplink

We investigate the cell coverage optimization problem for the massive multiple-input multiple-output (MIMO) uplink. By deploying tilt-adjustable antenna arrays at the base stations, cell coverage optimization can become a promising technique which is able to strike a compromise between covering cell-edge users and pilot contamination suppression. We formulate a detailed description of this optimization problem by maximizing the cell throughput, which is shown to be mainly determined by the user distribution within several key geometrical regions. Then, the formulated problem is applied to different example scenarios: for a network with hexagonal shaped cells and uniformly distributed users, we derive an analytical lower bound of the ergodic throughput in the objective cell, based on which, it is shown that the optimal choice for the cell coverage should ensure that the coverage of different cells does not overlap; for a more generic network with sectoral shaped cells and non-uniformly distributed users, we propose an analytical approximation of the ergodic throughput. After that, a practical coverage optimization algorithm is proposed, where the optimal solution can be easily obtained through a simple one-dimensional line searching within a confined searching region. Our numerical results show that the proposed coverage optimization method is able to greatly increase the system throughput in macrocells for the massive MIMO uplink transmission, compared with the traditional schemes where the cell coverage is fixed.

Old Town Glasgow: Squalor, Agitation and City Improvements

In 1862, Glasgow Corporation initiated the first of a series of three legislative acts which would become known collectively as the City Improvements Acts. Despite having some influence on the nature of the built fabric on the expanding city as a whole, the most extensive consequences of these acts was reserved for one specific area of the city, the remnants of the medieval Old Town. As the city had expanded towards all points of the compass in a regular, grid-iron structure throughout the nineteenth century, the Old Town remained singularly as a densely wrought fabric of medieval wynds, vennels, oblique passageways and accelerated tenementalisation. Here, as the rest of the city began to assume the form of an ordered entity, visible and classifiable, one could still find and addresses such as ‘Bridgegate, No. 29, backland, stair first left, three up, right lobby, door facing’ (quoted in Pacione, 1995).

Unsurprisingly, this place, where proximity to the midden (dung-heap) was considered an enviable position, was seen by the authorities as a major health hazard and a source not only of cholera, but also of the more alarming typhoid epidemic of 1842. Accordingly, the demolitions which occurred in the backlands of the Old Town under the first of the acts, the Glasgow Police Act of 1862, were justified on health and medical grounds. But disease was not the only social problem thought to issue from this district. Reports from social reformers including Fredrick Engels suggested that the decay of the area’s physical fabric could be extended to the moral profile of its inhabitants. This was in such a state of degeneracy that there were calls for a nearby military barracks to be relocated to more salubrious climes because troops were routinely coming into contact ‘with the most dissolute and profligate portion of the population’ (Peter Clonston, Lord Provost, June 1861). Perhaps more worrying for the city fathers, however, was that the barracks’ arsenal was seen as a potential source of arms for the militant and often illegal cotton workers’ unions and organisations who inhabited the Old Town as well as the districts to the east. In fact, the Old Town and East End had been the site of numerous working class actions and riots since 1787, including a strike of 60,000 workers in 1820, 100,000 in 1838, and the so-called Bread Riots of 1848 where shouts of ‘Vive La Revolution’ were reported in the Gallowgate.

The events in Paris in 1848 precipitated Baron Hausmann’s interventions into that city. The boulevards were in turn visited by members of Glasgow Corporation and ultimately, it can be argued, provided an example for Old Town Glasgow. This paper suggests that the city improvement acts carried a similarly complex and pervasive agenda, one which embodied not only health, class conflict and sexual morality but also the more local condition of sectarianism. And, like in Paris, these were played out spatially in a extensive reconfiguration of the urban fabric of the Old Town which, through the creation of new streets and a railway yard, not only made it more amenable to large scale military manoeuvres but also, opened up the area to capitalist accumulation. By the end of the works, the medieval heritage of the Old Town had been almost completely razed, the working class and Catholic East End had, through the insertion of the railway yard, been isolated from the city centre and approximately 70,000 people had been made homeless.

A Community Driven Approach to Reconstruction Management

Without human beings, and human activities, hazards can strike but disasters cannot occur, they are not just natural phenomena but a social event (Van Der Zon, 2005). The rapid demand for reconstruction after disastrous events can result in the impacts of projects not being carefully considered from the outset and the opportunity to improve long-term physical and social community structures being neglected. The events that struck Banda Aceh in 2004 have been described as
a story of ‘two tsunamis’, the first being the natural hazard that struck and the second being the destruction of social structures that occurred as a result of unplanned, unregulated and uncoordinated response (Syukrizal et al, 2009). Measures must be in place to ensure that, while aiming to meet reconstruction
needs as rapidly as possible, the risk of re-occurring disaster impacts are reduced through both the physical structures and the capacity of the community who inhabit them. The paper explores issues facing reconstruction in a post-disaster scenario, drawing on the connections between physical and social reconstruction in order to address long term recovery solutions. It draws on a study of relevant literature and a six week pilot study spent in Haiti exploring the progress of recovery in the Haitian capital and the limitations still restricting reconstruction efforts. The study highlights the need for recovery management strategies that recognise the link between social and physical reconstruction and the significance of community based initiatives that see local residents driving recovery in terms of debris handling and rebuilding. It demonstrates how a community driven approach to physical reconstruction could also address the social impacts of events that, in the case of places such as Haiti, are still dramatically restricting recovery efforts.

Roadmap to clinical use of gold nanoparticles for radiation sensitization

The past decade has seen a dramatic increase in interest in the use of gold nanoparticles (GNPs) as radiation sensitizers for radiation therapy. This interest was initially driven by their strong absorption of ionizing radiation and the resulting ability to increase dose deposited within target volumes even at relatively low concentrations. These early observations are supported by extensive experimental validation, showing GNPs' efficacy at sensitizing tumors in both in vitro and in vivo systems to a range of types of ionizing radiation, including kilovoltage and megavoltage X rays as well as charged particles. Despite this experimental validation, there has been limited translation of GNP-mediated radiation sensitization to a clinical setting. One of the key challenges in this area is the wide range of experimental systems that have been investigated, spanning a range of particle sizes, shapes, and preparations. As a result, mechanisms of uptake and radiation sensitization have remained difficult to clearly identify. This has proven a significant impediment to the identification of optimal GNP formulations which strike a balance among their radiation sensitizing properties, their specificity to the tumors, their biocompatibility, and their imageability in vivo. This white paper reviews the current state of knowledge in each of the areas concerning the use of GNPs as radiosensitizers, and outlines the steps which will be required to advance GNP-enhanced radiation therapy from their current pre-clinical setting to clinical trials and eventual routine usage.