bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Validation of a Pore-Scale Derived Dimensionless Capillary Pressure Function for Imbibition Under Mixed-Wet Conditions
Authors: Zhou Y. , Helland J. O. , Hatzignatiou D. G. , Ahsan R. , Hiorth A.
Published: April 2016

In this work, we validate experimentally a dimensionless capillary pressure function for imbibition at mixed-wet conditionsthat we developed recently based on pore-scale modeling in rock images. The difference to Leverett's traditional J-function is that our dimensionless function accounts for wettability and initial water saturation after primary drainage through area-averaged, effective contact angles that depend on the wetting property and distribution of oil- and water-wet grain surfaces. We hypothesized that describing these effective contact angles as a function of Amott wettability index relates the pore- and core-scale wettability, and that pore-scale imbibition simulations can provide these relations for specific rocks. In the present work, we adopt the dimensionless function to scale imbibition capillary pressure data measured on mixed-wet sandstone and chalk cores. The measured data practically collapse to a unique curve when subjected to the dimensionless capillary pressure function. For each rock material, we employ the average, dimensionless curve to reproduce the measured capillary pressure curves and obtain excellent agreement. We also demonstrate two approaches to generate different capillary pressure curves at other mixed-wettability states than that available from the data used to generate the dimensionless curve. The first approach changes the shape of the spontaneous- and forced-imbibition segments of the capillary pressure curve while the saturation at zero capillary pressure is constant. The second approach shifts the vertical level of the entire capillary pressure curve, such that the Amott wetting index (and the saturation at zero capillary pressure) changes accordingly. Thus, integrating these two approaches with the dimensionless function yields increased flexibility to account for different mixed-wettability states. The validated dimensionless function scales mixed-wet capillary pressure curves from core samples accurately, which demonstrates its applicability to describe variations of wettability and permeability with capillary pressure in reservoir simulation models. This allows for improved utilization of core experiments in predicting reservoir performance. Reservoir simulation models can also employ the dimensionless function together with existing capillary pressure correlations.
Field Development Process Revealing Uncertainty Assessment Pitfalls
Authors: Morosov André Luís , Schiozer Denis José
Published: April 2016

The amount of information available for field development planning is limited, forcing the Production Strategy to be designed under great amounts of uncertainty. During its implementation, new information allows the adaptation of the strategy for economic gain. This work reproduces the field development process under geological uncertainty in case study UNISIM-I-D (benchmark case based on Namorado Field in Brazil). The main objectives are to evaluate the process and observe the evolution of risk curves, all in a controlled environment with real field features.

The methodology generates new geostatistical images based on new well logs, assimilates production data using an ensemble-based method and re-optimizes the production strategy using a hybrid algorithm. The field development is carried out by repeatedly applying this framework under human supervision. Each step is customized using algorithms to simplify the implementation and to reduce computational effort, making this methodology more appealing for practical use. New data are collected from a high-resolution reference model that does not belong to the ensemble of models. The process starts with a production strategy, previously optimized under the uncertainties of the case study, which yields the real economic outcome within the original uncertain range.

Results show high quality history matching that excessively reduced the risk range and the variability of the updated model sets. Optimizations on the production strategy, based on the updated ensembles, consistently increased the expected monetary value of the project without guaranteeing an increment in the real NPV. Applying the methodology repeatedly throughout the field development increased the EMV by 29% (from 1.532 to 1.975 billion USD) while the real NPV decreased 2% (from 1.346 to 1.319 billion USD), falling out of the expected range and revealing that the model sets did not fully represent the real field. The lack of good representation is aggravated by heterogeneities inherent to the unknown reservoir, which are difficult to identify using only well logs and production data.

The results from the application of a closed-loop reservoir development process in a controlled environment warn against similar hidden mechanisms happening on a real field development under similar circumstances. They reveal intrinsic pitfalls in reservoir modeling that may contribute to production forecast problems and call for a reflection on how reservoir uncertainty assessment is performed. We prove that large sets of models do not guarantee coverage of geologic uncertainties as the field development process naturally changes the risk curves.
Determining the Zeta Potential of Intact Shales via Electrophoresis
Authors: Hoxha B. B. , Sullivan G. , van Oort E. , Daigle H. , Schindler C.
Published: April 2016

The wettability of rocks is of fundamental importance to the understanding of fluid transport within hydrocarbon reservoirs. Wettability is intimately tied to the zeta potential, which is determined by the electrostatic forces among the rock's mineral constituents. Extensive prior research has been conducted into the relationship between wettability and surface forces of shale samples that have been ground up and/or otherwise been altered. However, very little attention has been given to measuring the zeta potential of the surface of unbroken, intact shale samples.

A new technique is explored in this paper that investigates the zeta potential of the actual surface of shale samples in one intact piece. The surface zeta potential of shales was found to be strongly determined by the mineral composition and the cation exchange capacity (CEC) of the shale. Shales containing higher amounts of silicates (e.g. quartz, feldspar, and clays such as Illite and Smectite) tended to be water-wet and exhibit higher negative zeta potential values. Shales that contained higher amounts of carbonates (dolomite, aragonite, calcite, etc.) were more oil-wet with zeta potential values that were less negative or slightly positive. Measurements were also performed on Berea and Boise sandstone in order to compare organic vs. inorganic samples. Results for common shales showed Mancos and Marcellus to be intermediate-wet, Oxford and Eagleford to be moderately oil-wet, and Arne to be highly water-wet. Additionally, the zeta potential was also studied in various ionic and nano-particle solutions.
Scalability and Performance Efficiency of History Matching Workflows using MCMC and Adjoint Techniques Applied to the Norne North Sea Reservoir Case Study
Authors: Schulze-Riegert Ralf , Nwakile Michael , Skripkin Sergey , Willen Yannick
Published: April 2016

An increasing number of field development projects include rigorous uncertainty quantification workflows based on parameterized subsurface uncertainties. Reservoir model calibration workflows for reservoir simulation models including historical production data, also called history matching, deliver non-unique solutions and remain technically challenging. In addition, the validation process of the reservoir simulation model often introduces a break of the conceptual connection to the geological model. This raises questions on how to quantify the deviation between the calibrated simulation model and the original geological model.

Workflow designs for history matching require scalable and efficient optimization techniques to address project needs. Derivative-free techniques like Markov Chain Monte Carlo (MCMC) are used for optimization and uncertainty quantification. Adjoint techniques derive analytical sensitivities directly from the flow equations. For history matching those sensitivities are efficiently used for property updates on grid block level. Both techniques have different characteristics and support alternative history matching strategies like global vs. local, stochastic vs. deterministic.

In this work both techniques will be applied in an integrated workflow design to the Norne field. The Norne field is a North Sea oil-and-gas reservoir with approximately 30 wells, with one third being used for WAG injection for pressure support. Field data was previously released by Statoil and made available for a public benchmark study (NTNU Norway) testing history matching techniques including production and time-lapsed seismic data.

We focus on well production data for history matching. MCMC is used for global parameter updates and uncertainty quantification in a Bayesian context. An implementation of an adjoint technique is applied for analytical sensitivity calculations and local parameter adjustments of rock properties. History matching results are presented for field wide and well-by-well production data. Consistency checks between updated and original geological model are presented for rock property distribution maps. Geostatistical measures including spatial correlations are used to quantify deviations between updated and original geological model. In conclusion scalability and performance efficiency of the practical workflow implementation is discussed with a perspective of a consistent feedback loop from history matching to geological modeling.
Multi-Scale Integration of 4D Seismic and Simulation Data to Improve Saturation Estimations
Authors: Correia Gil Gomes , Davolio Alessandra , Schiozer Denis José
Published: April 2016

Some difficulties are frequently associated with the integration of seismic and flow simulation datasets, especially related with the low vertical resolution of the seismic data and the uncertain estimations in the areas between the wells. One challenge is then the integration of both datasets in different scales, in order to take advantage of their characteristics. The present study proposes a redistribution of the reservoir saturation estimated with 4D seismic inversion methods, combining the information provided by the flow simulation in order to improve the quality of the estimations and their resolution.

The methodology comprehends a saturation redistribution algorithm that is applied to each reservoir block combining the information of two saturation maps: one derived from the 4D seismic data and the other estimated by the flow simulator. The final saturation estimation follows the vertical distribution given by the simulation data but keep the average behavior observed in the 4D seismic. In order to have a better control of the results, the methodology is applied to a synthetic dataset that includes a reservoir model with different grid resolutions: geomodel, simulation model and seismic model.

Two different case studies present the main results of the proposed methodology to improve the saturation predictions. The first case study represents an ideal solution being assumed that the base model (simulation model) is very similar to the reference model (geomodel that represents the true answer), remaining a few differences due to the different scales. In the second case study, the base model is selected between multiple realizations during the uncertainty reduction process. The results shows that is possible to improve the resolution of the saturation variation maps computed from 4D seismic data allowing the identification of new fine scale heterogeneities and providing better estimations of the saturation changes due to production. This methodology can also give additional clues in future history matching procedures through the identification of critical regions. With the continuous calibration of the models during a history matching process the results obtained with the redistribution method tend to improve, approaching the results obtained in the first case study.

The proposed redistribution method combines the best characteristics of the seismic and simulation data. It includes the higher sensibility of the seismic data to identify the areal distribution of the main anomalies and inserts the higher sensibility of the simulation data regarding the identification of vertical water flow trends due to gravitational effects. Thus, the procedure introduces, in the maps provided by 4D seismic, new information regarding the injection/production patterns that become more and more reliable as we approach the wells.
New Approaches of Using Fluid Level Data for Production Optimization and Reservoir Engineering Applications
Authors: Burgstaller C.
Published: April 2016

A new technology for fully automated fluid level measurements was developed during the past seven years. The paper describes the technical features of the new device and summarizes via case studies new approaches of using fluid level data for optimizing artificial lift systems and for reservoir engineering applications (well testing).

The unique feature of this system is its fully automated and purely electronic functioning. The measuring device is mounted on the casing outlet and, contrary to conventional devices, works without the need of a gas gun. It has a sampling rate of one measurement per minute. The measured fluid level data is transmitted from each wellsite to the operations center via standard communication systems. The fluid level data can be used as an input signal to a VSD (Variable Speed Drive) controller for automatic pump regulation, thereby enabling operators to run downhole pumps in a safer and more efficient way. The new device has successfully been used to avoid pump-off conditions and the resulting serious equipment damage of artificial lift systems. Due to the availability of online fluid level data, downhole pumps (ESPs and Sucker Rod Pumps) could be operated safely at more aggressive production rates.

The device can also be used to control a VSD to keep the fluid level in a well at a specific depth to avoid downhole flow conditions below the bubble point pressure in oil wells. This application has been used on several oil production wells to avoid the generation of free gas within the reservoir, which would decrease the relative oil permeability and could also have a negative impact on the ultimate recovery of a reservoir.

Furthermore, a transient multi-phase flow model has been developed which has successfully been applied to derive bottomhole flowing and build-up pressure for production performance monitoring and well testing applications from the continuously available fluid level data. Comparisons with pressure data from downhole gauges show a very good agreement.

The new approach of obtaining bottomhole flowing and build-up pressure data from continuous fluid level measurements has proven to be a valuable method to optimize operations of artificially lifted wells and to obtain valuable data for reservoir monitoring in a cost-effective way.
DAS/DTS/DSS/DPS/DxS - Do We Measure What Adds Value?
Authors: Gohari Kousha , Jutila Heikki , Kshirsagar Atul , Chattopadhyay Arijit , Mascagnini Carlos , Gryaznov Andrey , Kidd Peter , Zarei Faraj
Published: April 2016

Inwell measurement of rates and ratios do not allow operators to proactively control flow into the well. For intelligent fields there is a growing need for tools that enable engineers to ‘see’ further into the reservoir in order to adjust and/or change the flow control strategy as required. From a reservoir management perspective the most value can be achieved when implementing intelligent flow control systems coupled with surveillance tools. Hence, this study presents a way of defining a fit for purpose surveillance strategy that can be coupled with active flow control systems that facilitates the optimisation of the recovery efficiency.

A dynamic simulator was used to analyse and determine a monitoring strategy that provides the most cost effective method of understanding various phenomena occurring within the reservoir, such as water/gas encroachment. The intention of the study was to determine if the data set currently obtained is sufficient enough to provide a deep understanding of the reservoir. The dynamic simulator modelled the temperature, saturation and pressure changes and the post-processer was used to derive corresponding changes in resistivity and acoustic properties. The change in temperature was important to model in order to study the parameter for its surveillance value as well as to capture thermal effects on reservoir fluid properties and geomechanical properties. The electro-magnetic and acoustic properties were calculated using a well-known formulae; resistivity was derived by inverting the Archie equation.

Results from the study were used to specify what the surveillance tools should measure and what detection distance would allow operators to proactively adjust the flow control devices/valves in order to maximise the value of the development. Sensitivity and optimisation analysis was conducted to obtain the distance of investigation required by the surveillance. The study demonstrated that a simple 1-way coupling gives representative estimations of electro-magnetic and acoustic properties over field production time. This will be able to assist in determining which methods of surveillance can be used over the life of the field assisting in recommending a suitable data acquisition strategy to extract maximum value from the tools available; DAS/DTS/DSS/DPS/DxS, EM, seismic and other methods.

Simple 1-way coupling is often enough to estimate the change with suitable accuracy to assess feasibility of various surveillance techniques. DAS could have an application in continuous cross-well tomography to follow the flood front; this subject is to be studied further.
Theoretical Study of Oilfield Development in Constrained Urban Environment
Authors: Mishra Shubham , Hii Sing Kiet , Corbett Chip
Published: April 2016

We conducted a theoretical study to investigate the techniques for developing a geologically complex turbidite reservoir in highly constrained oil field underlying a city. Not only does the geology present significant challenge in terms of heterogeneity and anisotropy, the surface constraints make it very difficult to plan the development of wells because of health, safety, and environment (HSE) issues.

With a strong economic focus, the study incorporated various sensitivities and uncertainties in CAPEX and OPEX in establishing novel ways of optimizing infill well locations, drilling in an urban area, and enhancing hydrocarbon production through reservoir simulation practices. For reservoir simulation, well logs, production history, and laboratory data were taken from an analogous field. This, plus the presence of certain unique events in the history of some of the wells, imposed limits on the study.

The methodology of the dynamic modelling is unconventional in terms of analyzing the field for forecasting right after initialization, followed by a detailed history match considering the numerous complexities of a turbidite environment. This allows greater time for field development planning, which is typically given the least attention in modelling because of time constraints. The prediction comprises three cases—a no-further-action case, an infill drilling case, and a waterflood scenario. A combination of vertical and horizontal well trajectories was used to achieve the best output across a range of economic sensitivities over multiple scenarios. The study covered a broad range of realizations of well trajectories, well placement, optimized drilling, and production services, such as is done in a constrained urban environment like Los Angeles, California. Our modelled city was Houston, Texas, a well-known urban environment. As a result of the modelling, a technique was developed to account for environmentally safe development within this example.

The technological and economic conclusions make this a foundation study for profitable development of reservoirs underneath a populated area. The study may also be instrumental in exploitation of turbidite reservoirs, which present challenges in current North Sea and Brazil offshore development and in recently discovered submarine fans in the Gulf of Mexico deep marine environment.
Inconsistent Yield Responses Add Complexity to Identifying Optimum Soybean Seeding Depths
Authors: Cox William J. , Cherney Jerome Henry
Published: April 2016

Soybean [Glycine max (L.) Merr.] seeding depth from 2.54 to 3.81 cm is considered optimum in northern rainfed regions, despite limited recent field research. We evaluated four seeding depths (2.54, 3.81, 5.08, and 6.35 cm) in three separate field‐scale studies (2013 and 2014) in New York to identify optimum depth(s) on well‐drained silt loam, somewhat poorly drained silty clay/silt loam, and somewhat excessively drained gravelly loam sites. Quadratic regression equations predicted minimum yield (4.49 Mg ha−1) at 4.71 cm in 2013 but maximum yield (4.22 Mg ha−1) at 4.85 cm in 2014 on the silt loam. Soybean populations showed negative linear responses to seeding depth at the other two sites in both years, but yield did not respond to seeding depth on the silty clay/silt loam, and showed a positive quadratic response (maximum yield of 4.21 Mg ha−1 at 4.55 cm in 2013) on the gravelly loam. Yield component compensation (positive linear/quadratic responses of seeds plant−1 to seeding depth) probably limited negative yield effects of lower populations at deeper seeding depths on the silty clay/silt loam and gravelly loam sites. Inconsistent yield differences (4.4–5.8% on the silt loam and 6.8–9.7% on the gravelly loam), as indicated by year × seeding depth interactions at both sites and no response on the silt loam, underscore the complexity in identifying optimum soybean seeding depths. Furthermore, favorable emergence conditions (mostly > 80% plant establishment) prevailed so population and yield responses to seeding depth may differ under unfavorable conditions.

Core Ideas

Soybean seeding depth from 2.54 to 3.81 cm is considered optimum in northern rainfed regions.

Soybean yield showed site‐specific yield responses to seeding depth.

Site‐specific yield responses underscore the complexity in identifying an optimum soybean seeding depth.
Phosphorus Leaching in Soils Amended with Animal Manures Generated from Modified Diets
Authors: Toor Gurpal S. , Sims J. Thomas
Published: April 2016

New dietary modifications for dairy (reducing P content in feed) and poultry (addition of feed additives such as phytase) aim to reduce P excretion in manures. Our objective was to investigate if dietary changes were effective at reducing P leaching loss on land application of manures. We used 54 undisturbed lysimeters (30 cm diameter, 50 cm deep) collected from three typical mid‐Atlantic soils. Lysimeters received 85 kg total P ha−1 from fertilizer (superphosphate), dairy manures generated from low‐ or high‐P diets, or broiler litters generated from normal diet or reduced P‐ and phytase‐amended diets. Lysimeters were irrigated with 50 mm of water each week for 9 wk. The major forms of P in the leachate were dissolved (dissolved unreactive P > dissolved reactive P [DRP]) rather than particulate (total particulate P). The higher P solubility (100%) in superphosphate resulted in greater leaching of DRP, whereas the lower P solubility (<30%) in dairy manures or broiler litters resulted in lower DRP leaching from soils. Preferential flow in two soils caused greater DRP leaching; this effect was more pronounced in the superphosphate‐amended than in the manure/litter‐amended lysimeters. The dairy and poultry dietary modification was effective at reducing the amount of P in manures and litters. However, the application of treatments at similar P rate (85 kg ha−1) resulted in the addition of a higher amount of manure (54–66%) in lysimeters that received low‐P dairy manure–amended and phytase‐amended broiler litter, which then controlled P leaching from soils.

Core Ideas

Dissolved unreactive P was the major form leached from the mid‐Atlantic soils.

Existence of preferential flow pathways in soils caused greater P leaching.

Soil and manure characteristics controlled P leaching from soils.
Thermal Conductivity of Binary Sand Mixtures Evaluated through Full Water Content Range
Authors: Wallen Benjamin M. , Smits Kathleen M. , Sakaki Toshihiro , Howington Stacy E. , Deepagoda T.K.K. Chamindu
Published: April 2016

Core Ideas

Thermal conductivity and water content relationship based upon mixtures are distinct.

Systematic change in particle fine fraction directly affects thermal conductivity.

Strong correlation between density and thermal conductivity

Campbell model well predicts thermal conductivity with all four parameters calibrated.

Lu and Dong model well predicts thermal conductivity with both parameters calibrated.

A soil's grain‐size distribution affects its physical and hydraulic properties; however, little is known about its effect on soil thermal properties. To better understand how grain‐size distribution affects soil thermal properties, specifically the effective thermal conductivity, a set of laboratory experiments was performed using binary mixtures of two uniform sands tightly packed with seven different mixing fractions over the full range of saturation. For each binary mixture, the effective thermal conductivity, λ, capillary pressure, hc, and volumetric water content, θ, were measured. Results demonstrated that the λ–θ relationship exhibited distinct characteristics based on the percentage of fine‐ and coarse‐grained sands. We further compared measured λ–θ properties with independent estimates from two semi‐empirical models (Campbell Model and Lu and Dong Model) to evaluate the models' applicability in relation to physically based parameters associated with changes in soil mixing (e.g., porosity and grain size). Both models were able to fit experimental data but to varying degrees based on the number of physically based parameters used. In general, model improvements are needed to capture the λ–θ relationship solely on physically based parameters.
Soil Characteristics and Wind Erosion Potential of Wheat–Oilseed–Fallow Cropping Systems
Authors: Sharratt Brenton , Schillinger William F.
Published: April 2016

Core Ideas

Oilseeds are integral in producing biofuel in the Pacific Northwest.

Wind erosion may escalate as a result of growing oilseeds in rotation with wheat.

The impact of oilseeds on soil properties that govern wind erosion is largely unknown.

Oilseeds resulted in less residue biomass and cover than conventional wheat rotations.

Oilseed crop residue must be carefully managed to minimize wind erosion.

Oilseeds are integral to the production of biofuels and diversifying rainfed cropping systems in the US Pacific Northwest (PNW). However, there is evidence to suggest greater potential for wind erosion when growing oilseeds in wheat (Triticum aestivum L.) rotations. Little is known concerning the impact of growing oilseeds on the soil surface characteristics that affect erosion. Soil characteristics were examined during the fallow phase of three crop rotations: (i) winter wheat–summer fallow (WW‐SF), (ii) winter wheat–camelina (Camelina sativa L. Grantz)–summer fallow (WW‐C‐SF), and (iii) winter wheat–safflower (Carthamus tinctorius L.)–summer fallow (WW‐S‐SF) at Lind and Ritzville, WA. Crop residue biomass and soil water content, roughness, surface strength, and aggregate size distribution were measured immediately after sowing winter wheat. Camelina and safflower did not affect soil water content, random roughness, penetration resistance, geometric mean diameter, or the erodible fraction, possibly due to the short duration over which the rotations were monitored in this study. Flat residue biomass and cover, however, tended to be greater in the WW–SF rotation. The Revised Wind Erosion Equation suggested that sediment transport could be from 57 to 212% greater for the WW‐C‐SF or WW‐S‐SF than the WW‐SF rotation due to differences in crop residue characteristics after sowing wheat. These results indicate that crop residue must be carefully managed to minimize the occurrence and intensity of wind erosion from dryland oilseed cropping systems in the PNW. Specifically, no‐till management may be required to manage crop residues during the fallow phase of a wheat–oilseed–fallow rotation to control wind erosion.
From Semiotics to Philosophy: Daring to Ask the Obvious
Authors: Saltz David Z.
Published: April 2016

From the late 1960s through the 1980s a steadily-expanding group of international scholars joined forces to develop a comprehensive and unified semiotic theory of theatre. The semiotic wave had largely subsided by the early 1990s, leaving in its wake a profound, and largely justified, scepticism about universal, essentialist, and ahistorical theoretical models. It is possible, however, to ask basic philosophical questions about the ‘nature’ of theatre and performance without falling into the trap of universalizing or essentializing what are, in fact, historically and/or culturally specific practices and biases. In this essay, I advocate an open-ended and dialogic process that characterizes the work of many contemporary philosophers, in both the analytic and continental traditions, and in particular those who have been inspired by the late-Wittgensteinian notion of philosophy as a kind of conceptual therapy.
On Performative Philosophy – 10 impulses for discussion from [soundcheck philosophie]
Authors: Gauß Eva Maria , Totzke Rainer
Published: April 2016

Since 2011, the philosophy-performance festival, [soundcheck philosophie] has been gathering protagonists in German-speaking countries, who seek and intend to cultivate a certain practice in philosophy. This practice takes philosophy - focussing not only on written texts but also on the fundamental oral situations that take place within pilosophy - and presents it artistically and/or through media. In this context. The term ‘Performative Philosophy’ is meant as a working concept for finding criteria and developing contemporary expressions and forms of doing pilosophy. The [soundcheck philosophie] festival and the association responsible for it, Expedition Philosophie / Internationale Gesellschaft für Performative Philosophie, are understood as a forum for discourse. The 10 theses at the end of this article are intended to initiate discussion. Informed by the well-known yet unique structure of an oral conversation, where a lot of things are mentioned out of context and the topic often remains to be discovered, we would also like to contribute impulses for conversation. With this in mind, we have incorporated 10 conversational impulses that answer, tell, ask, state, chat, riddle and reflect about the undertaking of the project of Performative Philosophy.
Tragedy, Immanence, and the Persistence of Semblance
Authors: Gritzner Karoline
Published: April 2016

The form of tragedy has been central to philosophical projects since classical antiquity, and it gained special critical import as a result of the so-called 'tragic turning within philosophy' during the Romantic period of German Idealism (see Beistegui 2000). The aim of this short paper is to address the notion of aesthetic appearance (semblance, Schein) within aesthetic theory (Theodor W. Adorno) and in contemporary tragic theatre (Howard Barker) and to show that the problem of semblance re-appears as a productive critical category in the current discourse of performance philosophy.
Arsenic from community water fluoridation: quantifying the effect
Authors: Peterson Emily , Shapiro Howard , Li Ye , Minnery John G. , Copes Ray
Published: April 2016

Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.
Population-based study of intra-household gender differences in water insecurity: reliability and validity of a survey instrument for use in rural Uganda
Authors: Tsai Alexander C. , Kakuhikire Bernard , Mushavi Rumbidzai , Vořechovská Dagmar , Perkins Jessica M. , McDonough Amy Q. , Bangsberg David R.
Published: April 2016

Hundreds of millions of people worldwide lack adequate access to water. Water insecurity, which is defined as having limited or uncertain availability of safe water or the ability to acquire safe water in socially acceptable ways, is typically overlooked by development organizations focusing on water availability. To address the urgent need in the literature for validated measures of water insecurity, we conducted a population-based study in rural Uganda with 327 reproductive-age women and 204 linked men from the same households. We used a novel method of photo identification so that we could accurately elicit study participants’ primary household water sources, thereby enabling us to identify water sources for objective water quality testing and distance/elevation measurement. Our psychometric analyses provided strong evidence of the internal structure, reliability, and validity of a new eight-item Household Water Insecurity Access Scale (HWIAS). Important intra-household gender differences in perceptions of water insecurity were observed, with men generally perceiving household water insecurity as being less severe compared to women. In summary, the HWIAS represents a reliable and valid measure of water insecurity, particularly among women, and may be useful for informing and evaluating interventions to improve water access in resource-limited settings.
Occurrence of antibiotics in pharmaceutical industrial wastewater, wastewater treatment plant and sea waters in Tunisia
Authors: Tahrani Leyla , Van Loco Joris , Ben Mansour Hedi , Reyns Tim
Published: April 2016

Antibiotics are among the most commonly used group of pharmaceuticals in human medicine. They can therefore reach surface and groundwater bodies through different routes, such as wastewater treatment plant effluents, surface runoff, or infiltration of water used for agricultural purposes. It is well known that antibiotics pose a significant risk to environmental and human health, even at low concentrations. The aim of the present study was to evaluate the presence of aminoglycosides and phenicol antibiotics in municipal wastewaters, sea water and pharmaceutical effluents in Tunisia. All analysed water samples contained detectable levels of aminoglycoside and phenicol antibiotics. The highest concentrations in wastewater influents were observed for neomycin and kanamycin B (16.4ng mL−1 and 7.5 ng mL−1, respectively). Chloramphenicol was found in wastewater influents up to 3 ng mL−1. It was observed that the waste water treatment plants were not efficient in completely removing these antibiotics. Chloramphenicol and florfenicol were found in sea water samples near aquaculture sites at levels up to, respectively, 15.6 ng mL−1 and 18.4 ng mL−1. Also aminoglycoside antibiotics were found near aquaculture sites with the highest concentration of 3.4 ng mL−1 for streptomycin. In pharmaceutical effluents, only gentamycin was found at concentrations up to 19 ng mL−1 over a sampling period of four months.
Age and Outcomes Associated with BP in Patients with Incident CKD
Authors: Kovesdy Csaba P. , Alrifai Ahmed , Gosmanova Elvira O. , Lu Jun Ling , Canada Robert B. , Wall Barry M. , Hung Adriana M. , Molnar Miklos Z. , Kalantar-Zadeh Kamyar
Published: April 2016

Background and objectives

Hypertension is the most important treatable risk factor for cardiovascular outcomes. Many patients with CKD are elderly, but the ideal BP in these individuals is unknown.

Design, setting, participants, & measurements

From among 339,887 patients with incident eGFR<60 ml/min per 1.73 m2, we examined associations of systolic BP (SBP) and diastolic BP (DBP) with all-cause mortality, incident coronary heart disease (CHD), ischemic strokes, and ESRD from the time of developing CKD until the end of follow-up (July 26, 2013, for mortality, CHD, and stroke, and December 31, 2011, for ESRD) in multivariable-adjusted survival models categorized by patients’ age.

Results

Of the total cohort, 300,424 (88%) had complete data for multivariable analysis. Both SBP and DBP showed a U-shaped association with mortality. SBP displayed a linear association with CHD, stroke, and ESRD, whereas DBP showed no consistent association with either. SBP>140 mmHg was associated with higher incidence of all examined outcomes, but with an incremental attenuation of the observed risk in older compared with younger patients (P<0.05 for interaction) The adjusted hazard ratios and 95% confidence intervals associated with SBP≥170 mmHg (compared with 130–139 mmHg) in patients <50, 50–59, 60–69, 70–79, and ≥80 years were 1.95 (1.34 to 2.84), 2.01 (1.75 to 2.30), 1.68 (1.49 to 1.89), 1.39 (1.25 to 1.54), and 1.30 (1.17 to 1.44), respectively. The risk of incident CHD, stroke, and ESRD was incrementally higher with higher SBP in patients aged <80 years but showed no consistent association in those aged ≥80 years (P<0.05 for interaction for all outcomes).

Conclusions

In veterans with incident CKD, SBP showed different associations in older versus younger patients. The association of higher SBP with adverse outcomes was present but markedly reduced in older individuals, especially in those aged ≥80 years. Elevated DBP showed no consistent association with vascular outcomes in patients with incident CKD.
Does Self-Certification Encourage or Reduce Opportunistic Behavior?
Authors: Ang Nicole , Cheng Mandy M.
Published: April 2016

We experimentally investigate the effectiveness of a self-certification requirement as an informal control to reduce opportunistic behavior. We predict and find that a requirement that managers sign to take sole responsibility for their decisions—even though the decision is kept private—acts as a “double-edged sword.” Using a capital investment setting involving two decision stages, we find that self-certifying managers are less likely to behave opportunistically at the first stage. However, at the second stage, managers are more likely to behave opportunistically if they previously self-certified an opportunistic decision. Additional analysis indicates that a monitoring-based control removes the effectiveness of self-certification altogether. Overall, we find that the effectiveness of a self-certification requirement in reducing opportunistic behavior is bounded by its timing and the presence of other controls; it is potentially useful when managers are making a first decision, and only in the absence of a formal monitoring system.

Data Availability: Data available upon request. Please contact the authors.
Securing Big Data Provenance for Auditors: The Big Data Provenance Black Box as Reliable Evidence
Authors: Appelbaum Deniz
Published: April 2016

The purpose of this article is to highlight a main issue regarding reliable audit evidence derived from Big Data—that of secure data provenance. Traditionally, audit evidence external to the client has been regarded as superior to other forms of evidence. However, regarding external “messy” Big Data sources that may be material to aspects of the audit, these sources may lack provenance and verifiability. That is, the origins of the data may be unclear and its log files incomplete. According to the standards, such evidence should be considered as less reliable for audit evidence. External auditors, as outsiders of the client, should be able to reproduce the data lifecycle or transaction path, which may not be possible in an electronic environment with incomplete provenance. Furthermore, this mapping or provenance of the data origins and history should be securely maintained so that it cannot be thwarted. This need for secure data provenance has been largely ignored by the business community in its haste to utilize Big Data, but has been acknowledged by extant systems research as being an area that requires attention. This paper contributes to the discussion of Big Data provenance through the lens of public company auditing, where the provenance and reliability of data sources and audit evidence are of paramount importance. This paper also proposes a system of secure provenance collection, the Big Data Provenance Black Box, which is derived from several streams of extant research.
Exploring Sustainability Control Systems' Integration: The Relevance of Sustainability Orientation
Authors: Ditillo Angelo , Lisi Irene Eleonora
Published: April 2016

We know very little about management control for sustainability. The objective of this paper is to overcome this void and to explain why and how sustainability control mechanisms vary in relation to firms' sustainability initiatives. In particular, we investigate how the integration of Sustainability Control Systems (SCSs) with the more traditional Management Control Systems (MCSs) is affected by managerial sustainability orientation. The empirical evidence based on a multiple-case design suggests that the nature of a firm's sustainability orientation represents the key trigger in explaining variations in SCSs' integration, and that this integration is facilitated by other potential enablers creating a positive environment supportive of sustainability initiatives. Insights on the complexities and potential dysfunctional consequences of the integration process are also offered. The paper concludes with some avenues for future research.
Sustainability Reporting Driving Forces and Management Control Systems
Authors: Herremans Irene M. , Nazari Jamal A.
Published: April 2016

This study investigates how seemingly similar external pressures elicited diverse sustainability reporting control systems and processes in a sample of Canadian companies in the oil and gas industry. Using interviews with companies and their stakeholders, we found that the type of sustainability reporting control systems depended on the managerial motivations and attitudes within companies as they responded to external pressures. More specifically, our results provide insight into how formal and informal sustainability reporting control systems were developed according to various managerial motivations and different types of stakeholder relationships. The type and balance between formal and informal control systems, in turn, influenced the sustainability reporting characteristics that the company was able to develop. We contribute to the literature by differentiating companies based on their institutional logics to deal with external pressures, managerial motivations, and stakeholder relationships, that in turn influenced their control system characteristics including reporting structures, information systems, and assurances.
An Understanding of the Differences between Internal and External Auditors in Obtaining Information about Internal Control Weaknesses
Authors: Burt Ian
Published: April 2016

The Institute of Internal Auditors (IIA) argues that internal auditors often have a strong “employee” identity within their organization. While external auditors are concerned that this employee identity might negatively impact internal auditors' objectivity, the IIA argues this identity can actually be beneficial as employees may be more willing to share sensitive and audit-relevant information with the internal auditor than they would with the external auditor. Through an experiment relying on the social identity and organizational silence literatures, I test the prediction that non-audit employees will identify more highly with the internal than the external auditor and they will thus, be willing to share more information about internal control weaknesses with the internal than the external auditor. The results from a moderated mediation analysis support this prediction and also show the effect is stronger as the severity of the internal control weakness increases. Overall, this research informs external auditors and regulators about conditions under which the internal auditor may have an advantage over the external auditor in obtaining information that could help improve audit quality. It also informs managers about an important role played by their internal auditors that may result in increased quality of the internal control system while also potentially lowering audit fees.
Transitions in the Embodied Experience After Stroke: Grounded Theory Study
Authors: Timothy Emily K. , Graham Fiona P. , Levack William M.M.
Published: April 2016

Background

The body is central to the practice of physical therapy, but clinical theory largely neglects the body as a concept. A better understanding of the embodied experience could enhance delivery of physical therapy.

Objectives

The purpose of this study was to gain an in-depth understanding of embodiment for people after stroke while transitioning from the hospital to the home.

Design and Methods

Seven people with stroke, aged 66 to 89 years, were interviewed 1 month after discharge from a stroke rehabilitation unit. Interviews were analyzed using grounded theory methods, and a theoretical model was developed.

Results

Two main themes in the embodied experience of stroke were: (1) “a divergent body-self,” where participants referred to an objective physical body, separate from their sense of self, and (2) “a cohesive body-self,” reflecting a sense that “it's all me.” The theme “a divergent body-self” included subthemes of a body that was “strange,” “unpredictable,” and “effortful.” In contrast, the theme “a cohesive body-self” comprised the subthemes “freedom,” “control,” and “self-identity,” reflecting experiences of bodily movement, personal independence, and self-identity. Participants fluxed between these perspectives, within moments and over time, with these perspectives influenced by “anchors,” including their environment, knowledge, and attitude.

Conclusions

The bodily experience of stroke is intimately connected with a person's sense of self. A person's social and physical environment, as well as his or her personal attributes, can serve to “anchor” that person more comfortably within his or her embodied experience of stroke. Theory that acknowledges the integral connection between body and self could enhance physical therapist practice. This study supports the need for physical therapists to be adequately informed to integrate the embodied experience in their practice when working with people after stroke.