Seismic response to evolving injection at the Rotokawa geothermal field, New Zealand

Catalogs of microseismicity are routinely compiled at geothermal reservoirs and provide valuable insights into reservoir structure and fluid movement. Hypocentral locations are typically used to infer the orientations of structures and constrain the extent of the permeable reservoir. However, frequency-magnitude distributions may contain additional, and underused, information about the distribution of pressure. Here, we present a four-year catalog of seismicity for the Rotokawa geothermal field in the central Taupō Volcanic Zone, New Zealand starting two years after the commissioning of the 140 MWe Nga Awa Purua power station. Using waveform-correlation-based signal detection we double the size of the previous earthquake catalog, refine the location and orientation of two reservoir faults and identify a new structure. We find the rate of seismicity to be insensitive to major changes in injection strategy during the study period, including the injectivity decline and shift of injection away from the dominant injector, RK24. We also map the spatial distribution of the earthquake frequency-magnitude distribution, or b-value, and show that it increases from ∼1.0 to ∼1.5 with increasing depth below the reservoir. As has been proposed at other reservoirs, we infer that these spatial variations reflect the distribution of pressure in the reservoir, where areas of high b-value correspond to areas of high pore-fluid pressure and a broad distribution of activated fractures. This analysis is not routinely conducted by geothermal operators but shows promise for using earthquake b-value as an additional tool for reservoir monitoring and management

Human Mission to Mars: Designing a Crew Expert Tool for a Safety Critical Environment

On a mission to other planets, the crew would come across situations and challenges that have not been foreseen even by experienced engineers, designers, scientists and previous explorers. This paper considers existing problem solving approaches that can help structure the development of ‘troubleshooting support tools’ for autonomous crews during long-duration missions. It also considers the suitability of these problem solving techniques for crew autonomous operations

Seismic Response to Injection Well Stimulation in a High-Temperature, High-Permeability Reservoir

Fluid injection into the Earth's crust can induce seismic events that cause damage to local infrastructure but also offer valuable insight into seismogenesis. The factors that influence the magnitude, location, and number of induced events remain poorly understood but include injection flow rate and pressure as well as reservoir temperature and permeability. The relationship between injection parameters and injection-induced seismicity in high-temperature, high-permeability reservoirs has not been extensively studied. Here we focus on the Ngatamariki geothermal field in the central Taupō Volcanic Zone, New Zealand, where three stimulation/injection tests have occurred since 2012. We present a catalog of seismicity from 2012 to 2015 created using a matched-filter detection technique. We analyze the stress state in the reservoir during the injection tests from first motion-derived focal mechanisms, yielding an average direction of maximum horizontal compressive stress (SHmax) consistent with the regional NE-SW trend. However, there is significant variation in the direction of maximum compressive stress (σ1), which may reflect geological differences between wells. We use the ratio of injection flow rate to overpressure, referred to as injectivity index, as a proxy for near-well permeability and compare changes in injectivity index to spatiotemporal characteristics of seismicity accompanying each test. Observed increases in injectivity index are generally poorly correlated with seismicity, suggesting that the locations of microearthquakes are not coincident with the zone of stimulation (i.e., increased permeability). Our findings augment a growing body of work suggesting that aseismic opening or slip, rather than seismic shear, is the active process driving well stimulation in many environments

Reaching millennium development goal 4 - the Gambia.

UNLABELLED: To describe how, through a DSS in a rural area of The Gambia, it has been possible to measure substantial reductions in child mortality rates and how we investigated whether the decline paralleled the registered fall in malaria incidence in the country. METHODS: Demographic surveillance data spanning 19.5 years (1 April 1989-30 September 2008) from 42 villages around the town of Farafenni, The Gambia, were used to estimate childhood mortality rates for neonatal, infant, child (1-4 years) and under-5 age groups. Data were presented in five a priori defined time periods, and annual rates per 1000 live births were derived from Kaplan-Meier survival probabilities. RESULTS: From 1989-1992 to 2004-2008, under-5 mortality declined by 56% (95% CI: 48-63%), from 165 (95% CI: 151-181) per 1000 live births to 74 (95% CI: 65-84) per 1000 live births. In 1- to 4-year-olds, mortality during the period 2004-2008 was 69% (95% CI: 60-76%) less than in 1989-1992. The corresponding mortality decline in infants was 39% (95% CI: 23-52%); in neonates, it was 38% (95% CI: 13-66%). The derived annual under-5 mortality rates declined from 159 per 1000 live births in 1990 to 45 per 1000 live births in 2008, thus implying an attainment of MDG4 seven years in advance of the target year of 2015. CONCLUSION: Achieving MDG4 is possible in poor, rural areas of Africa through widespread deployment of relatively simple measures that improve child survival, such as immunisation and effective malaria control

A Structured Approach to Scenario Generation for the Design of Crew Expert Tool

It is often difficult to identify the ways in which innovative systems can be used to support the crews on long duration space missions over the coming decades. This paper presents a structured approach towards scenario generation for crew autonomous operations during these future missions. The proposed approach will help to systematically generate scenarios that help define the design requirements for mission related equipment. A crew expert tool is used to illustrate our approach. This system is intended to help crewmembers identify and then resolve complex system failures in situations where it may not be possible to call upon immediate technical assistance from ground support staff. Our approach to scenario design helps to identify ways in which such an application may support crew tasks during the initial development of the application

Achieving comprehensive childhood immunization: an analysis of obstacles and opportunities in The Gambia

INTRODUCTION: Immunization is a vital component in the drive to decrease global childhood mortality, yet challenges remain in ensuring wide coverage of immunization and full immunization, particularly in low- and middle-income countries. This study assessed immunization coverage and the determinants of immunization in a semi-rural area in The Gambia. METHODS: Data were drawn from the Farafenni Health and Demographic Surveillance System. Children born within the surveillance area between January 2000 and December 2010 were included. Main outcomes assessed included measles, BCG and DTP vaccination status and full immunization by 12 months of age as reported on child healthcards. Predictor variables were evaluated based on a literature review and included gender, ethnicity, area of residence, household wealth and mother's age. RESULTS: Of the 7363 children included in the study, immunization coverage was 73% (CI 72-74) for measles, 86% (CI 86-87) for BCG, 79% (CI 78-80) for three doses of DTP and 52% (CI 51-53) for full immunization. Coverage was significantly associated with area of residence and ethnicity, with children in urban areas and of Mandinka ethnicity being least likely to be fully immunized. CONCLUSIONS: Despite high levels of coverage of many individual vaccines, delivery of vaccinations later in the schedule and achieving high coverage of full immunization remain challenges, even in a country with a committed childhood immunization programme, such as The Gambia. Our data indicate areas for targeted interventions by the national Expanded Programme of Immunization

Trust and Risk Relationship Analysis on a Workflow Basis: A Use Case

Trust and risk are often seen in proportion to each other; as such, high trust may induce low risk and vice versa. However, recent research argues that trust and risk relationship is implicit rather than proportional. Considering that trust and risk are implicit, this paper proposes for the first time a novel approach to view trust and risk on a basis of a W3C PROV provenance data model applied in a healthcare domain. We argue that high trust in healthcare domain can be placed in data despite of its high risk, and low trust data can have low risk depending on data quality attributes and its provenance. This is demonstrated by our trust and risk models applied to the BII case study data. The proposed theoretical approach first calculates risk values at each workflow step considering PROV concepts and second, aggregates the final risk score for the whole provenance chain. Different from risk model, trust of a workflow is derived by applying DS/AHP method. The results prove our assumption that trust and risk relationship is implicit

Promoting Community Engagement: A Campus-Wide Approach to Applied Learning

Applied learning pedagogy has gained momentum in recent decades. Simultaneously, a call for universities to respond to the needs of local and global communities has prompted a focus on community engagement in higher education. The purpose of this paper is to describe the development of the Applied Learning and Teaching Community (ALTC), an initiative designed to further integrate applied learning—including community engagement— into the identity, practice, and teaching ethos of the university. With a focus on sustainability, the ALTC has evolved into an expansive model that involves faculty, staff, students, and other supporters across campus. A discussion of the ALTC’s relevance in the context of current trends in higher education is included

Parameters affecting ion intensities in transmission-mode Direct Analysis in Real-Time mass spectrometry

A survey of the effect of temperature, transmission module material and analysis time on ion intensities in transmission mode direct analysis in real time mass spectrometry is presented. Ion intensity profiles obtained for two related compounds are similar when analysed separately but are very different when analysed as a mixture