Saline aquifer CO2 storage : a demonstration project at the Sleipner Field : Work Area 5 (Geophysics) : gravity modelling of the CO2 bubble

A principal aim of the SACS project is to monitor the injected CO2 by geophysical methods and to develop a robust and repeatable monitoring and verification methodology for future CO2 sequestration operations. This report evaluates the applicability of microgravity surveys as a means of monitoring the future subsurface distribution and migration of the Sleipner CO2 bubble. Time-lapse seismic data acquired in 1999, after 2.3 MT of CO2 injection, show an exceptionally clear image of the CO2 bubble, characterised by very high reflection amplitudes. The outer envelope of the amplitude anomaly roughly defines an elliptical cylindrical ‘bubble envelope’, ~ 225 m high, with a major axis of ~ 1500 m oriented NNE and a minor axis of ~ 600 m. Gravity modelling was based on a number of scenarios. Two ‘in situ’ scenarios assume that the CO2 is entirely contained within the bubble envelope. The 1999 and 2001 in situ models assume respectively that 2.3 MT and 4MT of CO2 are contained within the envelope. Two migration scenarios are also modelled. The first assumes that 2.3MT of CO2 migrate vertically upwards into the overlying caprock succession to between depths of 375 and 600 m. The second migration model looks further ahead to the situation where 3 x 107 m3 (~ 10.5 – 21.0 MT depending on the density) of CO2 have been injected, and migrate laterally beneath the caprock at the top of the reservoir. Results depend strongly on the assumed density of the injected CO2 at reservoir conditions, which is subject to significant uncertainty. Only one, poorly-constrained, reservoir temperature measurement of 37 ° C is available. A density-depth profile based on this suggests that the density of CO2 in the reservoir is ~ 700 kgm-3. However the possibility of significantly lower densities cannot be discounted and modelling also includes a lower density case of 350 kgm-3. The 1999 and 2001 in situ cases produce anomalies which would be barely detectable if the higher density of CO2 is assumed. With the lower density however anomalies should be readily detectable with a modern seabed gravimeter. The vertical migration scenario indicates that large-scale vertical migration into the caprock, to depths where densities would be unequivocally lower, would be readily detected. The lateral migration scenario, whereby a single thin layer of CO2 migrates beneath the top reservoir seal, produces small anomalies which may be locally detectable but with insufficient resolution to enable effective migration mapping. However if lateral migration is via several layers, beneath intra-reservoir shales, then anomalies should be more usefully measurable. Obtaining time-lapse gravimeter readings directly above the bubble would appear to offer the best chance of obtaining useful information. Coupled with geometric information provided by the time-lapse seismic data, the gravity should be able to discriminate between the low and high CO2 density scenarios. This would provide important constraints on future reservoir modelling and also the volume estimates based on the seismic velocity pushdown effect. Related to this, gravity data would offer the potential to provide independent verification of the amount of CO2 sequestered. In addition gravimetric surveys above the bubble could provide an effective ‘early warning’ of major caprock breaching

Genesis of ancestral haplotypes: RNA modifications and reverse transcription–mediated polymorphisms

Understanding the genesis of the block haplotype structure of the genome is a major challenge. With the completion of the sequencing of the Human Genome and the initiation of the HapMap project the concept that the chromosomes of the mammalian genome are a mosaic, or patchwork, of conserved extended block haplotype sequences is now accepted by the mainstream genomics research community. Ancestral Haplotypes (AHs) can be viewed as a recombined string of smaller Polymorphic Frozen Blocks (PFBs). How have such variant extended DNA sequence tracts emerged in evolution? Here the relevant literature on the problem is reviewed from various fields of molecular and cell biology particularly molecular immunology and comparative and functional genomics. Based on our synthesis we then advance a testable molecular and cellular model. A critical part of the analysis concerns the origin of the strand biased mutation signatures in the transcribed regions of the human and higher primate genome, A-to-G versus T-to-C (ratio ~1.5 fold) and C-to-T versus G-to-A (≥1.5 fold). A comparison and evaluation of the current state of the fields of immunoglobulin Somatic Hypermutation (SHM) and Transcription-Coupled DNA Repair focused on how mutations in newly synthesized RNA might be copied back to DNA thus accounting for some of the genome-wide strand biases (e.g., the A-to-G vs T-to-C component of the strand biased spectrum). We hypothesize that the genesis of PFBs and extended AHs occurs during mutagenic episodes in evolution (e.g., retroviral infections) and that many of the critical DNA sequence diversifying events occur first at the RNA level, e.g., recombination between RNA strings resulting in tandem and dispersed RNA duplications (retroduplications), RNA mutations via adenosine-to-inosine pre-mRNA editing events as well as error prone RNA synthesis. These are then copied back into DNA by a cellular reverse transcription process (also likely to be error-prone) that we have called "reverse transcription-mediated long DNA conversion." Finally we suggest that all these activities and others can be envisaged as being brought physically under the umbrella of special sites in the nucleus involved in transcription known as "transcription factories."

A Political Economy of Privatization Contracts : The Case of Water and Sanitation in Ghana and Argentina

This document is the Accepted Manuscript version of the following article: Hulya Dagdeviren, Simon A. Robertson, 'A Political Economy of Privatization Contracts: The Case of Water and Sanitation in Ghana and Argentina', Competition & Change, Vol. 18 (2): 150-163, April 2014. The final, published version is available online at DOI: https://doi.org/10.1179/1024529414Z.00000000053. Published by SAGE.In general, the process and outcomes of privatization have been studied from the point of view of efficiency. In this article, we consider issues in the course of contract design, implementation, management and enforcement in privatized public services and utilities. The study is based on two case studies, involving several water concessions in Argentina and a management contract in the urban water sector in Ghana. Three key arguments are presented on the basis of these case studies. The first is that an individualistic analytical framework is often utilized by the mainstream economic perspectives, but these are inadequate for a comparative assessment of private versus public provision in public services where there are distinct collective or group interests and hence a wider socio-economic context and representation of different interests becomes highly important. Instead, the article proposes a political economy perspective, which pays due attention to distributional issues, group interests, ideology of states and power relations for the assessment of privatization contracts. Second, the administrative capacity of states and their resources play a key role for the outcomes of privatization. Finally, while some contractual issues could be resolved through resourcing and experience over time, others are inherent to the contractual relations with little prospect of remedy.Peer reviewe

A geological model of London and the Thames Valley, southeast England

Many geological survey organisations have started delivering digital geological models as part of their role. This article describes the British Geological Survey (BGS) model for London and the Thames Valley in southeast England. The model covers 4800 km2 and extends to several hundred metres depth. It includes extensive spreads of Quaternary river terraces and alluvium of the Thames drainage system resting on faulted and folded Palaeogene and Cretaceous bedrock strata. The model extends to the base of the Jurassic sedimentary rocks. The baseline datasets used and the uses and limitations of the model are given. The model has been used to generate grids for the elevation of the base of the Quaternary, the thickness of Quaternary deposits, and enabled a reassessment of the subcrop distribution and faulting of the Palaeogene and Cretaceous bedrock units especially beneath the Quaternary deposits. Digital outputs from the model include representations of geological surfaces, which can be used in GIS, CAD and geological modelling software, and also graphic depictions such as a fence diagram of cross-sections through the model. The model can be viewed as a whole, and be dissected, in the BGS Lithoframe Viewer. Spatial queries of this and other BGS models, at specific points, along defined lines or at a specified depth, can be performed with the new BGS Groundhog application, which delivers template-based reports. The model should be viewed as a first version that should be improved further, and kept up to date, as new data and understanding emerges

A generalized definition of reactivity for ecological systems and the problem of transient species dynamics

1. Perturbations to an ecosystem's steady state can trigger transient responses of great ecological relevance. Asymptotic stability determines whether a generic perturbation will fade out in the long run, but falls short of characterizing the dynamics immediately after an equilibrium has been perturbed. Reactivity, traditionally defined as the maximum instantaneous growth rate of small perturbations to a stable steady state, is a simple yet powerful measure of the short-term instability of a system as a whole. In many ecological applications, however, it could be important to focus on the reactivity properties of just some specific, problem-dependent state variables, such as the abundance of a focal species engaged in interspecific competition, either predators or preys in a trophic community, or infectious individuals in disease transmission. 2. We propose a generalized definition of reactivity (g-reactivity) that allows to evaluate the differential contribution of the state space components to the transient behaviour of an ecological system following a perturbation. Our definition is based on the dynamic analysis of a system output, corresponding to an ecologically motivated linear transformation of the relevant state variables. We demonstrate that the g-reactivity properties of an equilibrium are determined by the dominant eigenvalue of a Hermitian matrix that can be easily obtained from the Jacobian associated with the equilibrium and the system output transformation. 3. As a testbed for our methodological framework, we analyse the g-reactivity properties of simple spatially implicit metapopulation models of some prototypical ecological interactions, namely competition, predation and transmission of an infectious disease. We identify conditions for the temporary coexistence of an invader with a (possibly competitively superior) resident species, for transitory invasion of either prey or predator in otherwise predator- or prey-dominated ecosystems, and for transient epidemic outbreaks. 4. Through suitable examples, we show that characterizing the transient dynamics associated with an ecosystem's steady state can be, in some cases, as important as determining its asymptotic behaviour, from both theoretical and management perspective. Because g-reactivity analysis can be performed for systems of any complexity in a relatively straightforward way, we conclude that it may represent a useful addition to the toolbox of quantitative ecologists

Viruses, variants and vaccines

The current SARS-CoV-2 pandemic has brought a number of major global clinical, sociological and economic issues into sharp focus. We address some of these issues, focusing on short-term factors such as virus mutations and vaccine efficacy, and also considering the longer-term implications of the current pandemic. We discuss societal responses to the presence of a pathogen that will probably remain in circulation for decades or longer, and to future new emergent viruses.The South African Medical Research Council and the National Research Foundation.http://www.samj.org.zaam2022BiochemistryGeneticsImmunologyMicrobiology and Plant Patholog

NASA's Understanding of Risk in Apollo and Shuttle

Mathematical risk analysis was used in Apollo, but it gave unacceptably pessimistic resultsand was discontinued. Shuttle was designed without using risk analysis, under the assumptionthat good engineering would make it very safe. This approach led to an unnecessarily riskydesign, which directly led to the Shuttle tragedies. Although the Challenger disaster wasdirectly due to a mistaken launch decision, it might have been avoided by a safer design. Theultimate cause of the Shuttle tragedies was the Apollo era decision to abandon risk analysis

Superscaling of Inclusive Electron Scattering from Nuclei

We investigate the degree to which the concept of superscaling, initially developed within the framework of the relativistic Fermi gas model, applies to inclusive electron scattering from nuclei. We find that data obtained from the low energy loss side of the quasielastic peak exhibit the superscaling property, i.e., the scaling functions f(\psi') are not only independent of momentum transfer (the usual type of scaling: scaling of the first kind), but coincide for A \geq 4 when plotted versus a dimensionless scaling variable \psi' (scaling of the second kind). We use this behavior to study as yet poorly understood properties of the inclusive response at large electron energy loss.Comment: 33 pages, 12 color EPS figures, LaTeX2e using BoxedEPSF macros; email to [email protected]

The Behavioral Roots of Information Systems Security:Exploring Key Factors Related to Unethical IT Use

Unethical information technology (IT) use, related to activities such as hacking, software piracy, phishing, and spoofing, has become a major security concern for individuals, organizations, and society in terms of the threat to information systems (IS) security. While there is a growing body of work on this phenomenon, we notice several gaps, limitations, and inconsistencies in the literature. In order to further understand this complex phenomenon and reconcile past findings, we conduct an exploratory study to uncover the nomological network of key constructs salient to this phenomenon, and the nature of their interrelationships. Using a scenario-based study of young adult participants, and both linear and nonlinear analyses, we uncover key nuances of this phenomenon of unethical IT use. We find that unethical IT use is a complex phenomenon, often characterized by nonlinear and idiosyncratic relationships between the constructs that capture it. Overall, ethical beliefs held by the individuals, along with economic, social, and technological considerations are found to be relevant to this phenomenon. In terms of practical implications, these results suggest that multiple interventions at various levels may be required to combat this growing threat to IS security

A mixed valence complex of gold with dimethyl sulfoxide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24578/1/0000861.pd