Dynamic reservoir-condition microtomography of reactive transport in complex carbonates: effect of initial pore structure and initial brine pH

We study the impact of brine acidity and initial pore structure on the dynamics of fluid/solid reaction at high Péclet numbers and low Damköhler numbers. A laboratory μ-CT scanner was used to image the dissolution of Ketton, Estaillades, and Portland limestones in the presence of CO2-acidified brine at reservoir conditions (10 MPa and 50°C) at two injected acid strengths for a period of 4 hours. Each sample was scanned between 6 and 10 times at ∼4 μm resolution and multiple effluent samples were extracted. The images were used as inputs into flow simulations, and analysed for dynamic changes in porosity, permeability, and reaction rate. Additionally, the effluent samples were used to verify the image-measured porosity changes. We find that initial brine acidity and pore structure determine the type of dissolution. Dissolution is either uniform where the porosity increases evenly both spatially and temporally, or occurs as channelling where the porosity increase is concentrated in preferential flow paths. Ketton, which has a relatively homogeneous pore structure, dissolved uniformly at pH = 3.6 but showed more channelized flow at pH = 3.1. In Estaillades and Portland, increasingly complex carbonates, channelized flow was observed at both acidities with the channel forming faster at lower pH. It was found that the effluent pH, which is higher than that injected, is a reasonably good indicator of effective reaction rate during uniform dissolution, but a poor indicator during channelling. The overall effective reaction rate was up to 18 times lower than the batch reaction rate measured on a flat surface at the effluent pH, with the lowest reaction rates in the samples with the most channelized flow, confirming that transport limitations are the dominant mechanism in determining reaction dynamics at the fluid/solid boundary

A pilot level decision analysis of thermionic reactor development strategy for nuclear electric propulsion

The development policy for thermionic reactors to provide electric propulsion and power for space exploration was analyzed to develop a logical procedure for selecting development alternatives that reflect the technical feasibility, JPL/NASA project objectives, and the economic environment of the project. The partial evolution of a decision model from the underlying philosophy of decision analysis to a deterministic pilot phase is presented, and the general manner in which this decision model can be employed to examine propulsion development alternatives is illustrated

Workplace well-being and support systems in journalism: comparative analysis of Germany and the United Kingdom

Contemporary thinking of journalism as a high emotional labour profession calls into question the systems that are, or should be, in place to support journalists with this labour and in this way mitigate any of its potentially negative consequences, such as those on well-being, mental and physical health, and job performance. By drawing on organisational and social support theories, this article examines the perceptions, expectations, and support needs of journalists in Germany and the United Kingdom, the two European countries with the biggest bodies of practising journalists. Qualitative interviews with 32 German and 34 British journalists reveal important similarities but also differences between the two countries. Specifically, in both countries journalists reported primarily relying on their psychological capital to deal with emotional labour, although many were unsure what exactly constitutes it or how it has been developed. In Germany the social and supervisor support were often mentioned as effective, while in the UK social support was at times found to be hindered by newsroom culture and supervisors’ lack of understanding of the job pressures. Finally, it has been suggested by journalists in both countries that organisational support could be improved by an offer of training in emotional literacy for both journalists and managers, establishment of a point of contact tasked with pastoral care, and fair, transparent and formal structures that encourage and enable journalists to effectively deal with emotional stressors in the job

`Boy!\u27: The Hinge of Colonial Double Talk

The French colonial enterprise in Africa enforced racial segregation, yet encouraged Africans to assimilate the French language, culture, and religion. The essay questions these contradictory policies through readings of Ferdinand Oyono\u27s novels. It argues that a figure that embodies undecidability—the colonial servant known as the boy —is the locus of the denaturalization of the identities that were simultaneously institutionalized and denied by the Manichaean colonial world

A Corrosion Control Manual for Rail Rapid Transit

This manual addresses corrosion problems in the design, contruction, and maintenance of rapid transit systems. Design and maintenance solutions are provided for each problem covered. The scope encompasses all facilities of urban rapid transit systems: structures and tracks, platforms and stations, power and signals, and cars. The types of corrosion and their causes as well as rapid transit properties are described. Corrosion control committees, and NASA, DOD, and ASTM specifications and design criteria to which reference is made in the manual are listed. A bibliography of papers and excerpts of reports is provided and a glossary of frequently used terms is included

Status of the Lattice and Tau Decay Determinations of alpha_s

The two highest precision determinations of alpha_s(M_Z^2), that based on the analysis of short-distance-sensitive lattice observables, and that based on an analysis of hadronic tau decay data, have, until very recently, given results which are not in good agreement. I review new versions of these analyses which bring the two determinations into excellent agreement, and discuss prospects for additional future improvements.Comment: Prepared for the Proceedings of the 5th International Conference on Quarks and Nuclear Physics, Beijing, China, Sept. 21-26, 200

Is the Birthing Unit Design Spatial Evaluation Tool valid for diverse groups?

© 2018 Australian College of Midwives Background: Awareness of the impact of the built environment on health care outcomes and experiences has led to efforts to redesign birthing environments. The Birth Unit Design Spatial Evaluation Tool was developed to inform such improvements, but it has only been validated with caseload midwives and women birthing in caseload models of care. Aim: To assess the content validity of the tool with four new participant groups: Birth unit midwives, Aboriginal or Torres Strait Islander women; women who had anticipated a vaginal birth after a caesarean; and women from refugee or culturally and linguistically diverse backgrounds. Methods: Participants completed a Likert-scale survey to rate the relevance of The Birth Unit Design Spatial Evaluation Tool's 69 items. Item-level content validity and Survey-level validity indices were calculated, with the achievement of validity set at >0.78 and >0.9 respectively. Results: Item-level content validity was achieved on 37 items for birth unit midwives (n = 10); 35 items for Aboriginal or Torres Strait Islander women (n = 6); 33 items for women who had anticipated a vaginal birth after a caesarean (n = 6); and 28 items for women from refugee or culturally and linguistically diverse backgrounds (n = 20). Survey-level content validity was not demonstrated in any group. Conclusion: Birth environment design remains significant to women and midwives, but the Birth Unit Design Spatial Evaluation Tool was not validated for these participant groups. Further research is needed, using innovative methodologies to address the subconscious level on which environment may influence experience and to disentangle the influence of confounding factors