bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accountable Corporate Parenting
Authors: Welbourne Penelope , Dixon John 
Published: July 2008

• Summary: This article explores some complex issues involved in promoting accountability in local authority public services. In the UK, a gap in accountability for services for Looked After children was identified by the High Court. We offer an analysis of policy initiatives developed in response. Citizen review, another approach to strengthening accountability in widespread use in the USA, is described and appraised. • Findings: Accountability in services for Looked After children in the UK has been substantially improved by recent developments in law and policy. However, it is argued that the continuing absence of external review and reliance on upward accountability still leaves a flawed structure. The paucity of quality evaluation of citizen participation in US is noted, but we identify its potential to promote both outward accountability and diversity in accountability and review. • Application: The article is a contribution to the ongoing analysis of accountability in public services, and promotes more inclusive practice in reviewing service provision. Its focus is on Looked After children, but some of the principles discussed are capable of application to other vulnerable groups and communities.
A molecular signaling model of platelet phosphoinositide and calcium regulation during homeostasis and P2Y1 activation
Authors: Purvis Jeremy E. , Chatterjee Manash S. , Brass Lawrence F. , Diamond Scott L. 
Published: July 2008

AbstractTo quantify how various molecular mechanisms are integrated to maintain platelet homeostasis and allow responsiveness to adenosine diphosphate (ADP), we developed a computational model of the human platelet. Existing kinetic information for 77 reactions, 132 fixed kinetic rate constants, and 70 species was combined with electrochemical calculations, measurements of platelet ultrastructure, novel experimental results, and published single-cell data. The model accurately predicted: (1) steady-state resting concentrations for intracellular calcium, inositol 1,4,5-trisphosphate, diacylglycerol, phosphatidic acid, phosphatidylinositol, phosphatidylinositol phosphate, and phosphatidylinositol 4,5-bisphosphate; (2) transient increases in intracellular calcium, inositol 1,4,5-trisphosphate, and Gq-GTP in response to ADP; and (3) the volume of the platelet dense tubular system. A more stringent test of the model involved stochastic simulation of individual platelets, which display an asynchronous calcium spiking behavior in response to ADP. Simulations accurately reproduced the broad frequency distribution of measured spiking events and demonstrated that asynchronous spiking was a consequence of stochastic fluctuations resulting from the small volume of the platelet. The model also provided insights into possible mechanisms of negative-feedback signaling, the relative potency of platelet agonists, and cell-to-cell variation across platelet populations. This integrative approach to platelet biology offers a novel and complementary strategy to traditional reductionist methods.
Cardiac autonomic activity and blood pressure among Nunavik Inuit adults exposed to environmental mercury: a cross-sectional study
Authors: Valera Beatriz , Dewailly Eric , Poirier Paul 
Published: July 2008

Abstract

Background
Mercury is a contaminant that reaches high levels in Nunavik (North of Quebec). It is transformed into methylmercury (MeHg) and accumulated in marine mammals and predator fish, an important part of the traditional Inuit diet. MeHg has been suggested to affect BP in adults and children while the influence on HRV has only been studied in children. We aimed to assess the impact of MeHg levels on HRV and BP in Inuit adults from Nunavik.

Methods
In the fall of 2004, the «Qanuippitaa?» Health Survey was conducted in Nunavik (Quebec, Canada) and information on HRV was collected among 280 adults aged 40 years and older. Indicators of the time and frequency domains of HRV were derived from a 2-hour Holter recording. BP was measured according to the Canadian Coalition for High Blood Pressure technique. Pulse pressure (PP) was the difference between systolic (SBP) and diastolic blood pressure (DBP). Blood mercury concentration was used as exposure biomarker. Statistical analysis was conducted through linear regression and multivariable linear regression was used to control for confounders.

Results
Mercury was negatively correlated with low frequency (LF) (r = -0.18; p = 0.02), the standard deviation of RR intervals (SDNN) (r = -0.14; p = 0.047) and the coefficient of variation of RR intervals (CVRR) (r = -0.18; p = 0.011) while correlations with other HRV parameters did not reach statistical significance. After adjusting for confounders, the association with LF (beta = -0.006; p = 0.93) became non significant. However, the association with SDANN became statistically significant (beta = -0.086; p = 0.026) and CVRR tended to decrease with blood mercury concentrations (beta = -0.057; p = 0.056). Mercury was positively correlated with SBP (r = 0.25; p < 0.0001) and PP (r = 0.33; p < 0.0001). After adjusting for confounders, these associations remained statistically significant (beta SBP = 4.77; p = 0.01 and beta PP = 3.40; p = 0.0036). Moreover, most of the HRV parameters correlated well with BP although SBP the best before adjustment for mercury exposure.

Conclusion
The results of this study suggest a deleterious impact of mercury on BP and HRV in adults. SBP and PP increased with blood mercury concentrations while SDANN decreased with blood mercury concentrations.
Risk prediction models with incomplete data with application to prediction of estrogen receptor-positive breast cancer: prospective data from the Nurses' Health Study
Authors: Rosner Bernard , Colditz Graham A , Iglehart J Dirk , Hankinson Susan E 
Published: July 2008

Abstract
Introduction
A number of breast cancer risk prediction models have been developed to provide insight into a woman's individual breast cancer risk. Although circulating levels of estradiol in postmenopausal women predict subsequent breast cancer risk, whether the addition of estradiol levels adds significantly to a model's predictive power has not previously been evaluated.

Methods
Using linear regression, the authors developed an imputed estradiol score using measured estradiol levels (the outcome) and both case status and risk factor data (for example, body mass index) from a nested case-control study conducted within a large prospective cohort study and used multiple imputation methods to develop an overall risk model including both risk factor data from the main cohort and estradiol levels from the nested case-control study.

Results
The authors evaluated the addition of imputed estradiol level to the previously published Rosner and Colditz log-incidence model for breast cancer risk prediction within the larger Nurses' Health Study cohort. The follow-up was from 1980 to 2000; during this time, 1,559 invasive estrogen receptor-positive breast cancer cases were confirmed. The addition of imputed estradiol levels significantly improved risk prediction; the age-specific concordance statistic increased from 0.635 ± 0.007 to 0.645 ± 0.007 (P < 0.001) after the addition of imputed estradiol.

Conclusion
Circulating estradiol levels in postmenopausal women appear to add to other lifestyle factors in predicting a woman's individual risk of breast cancer.
A Screening Model for CO2 Flooding and Storage in Gulf Coast Reservoirs Based on Dimensionless Groups
Authors: Wood Derek J. , Lake Larry W. , Johns Russell T. , Nunez Vanessa 
Published: July 2008

SummaryConcerns over global warming have led to interest in removing greenhouse gases, specifically CO2, from the atmosphere. Sequestration of CO2 in oil reservoirs as part of enhanced oil recovery (EOR) projects is one method that is being considered.This paper first presents the scaling groups necessary to describe CO2 flooding for a typical line-drive pattern and then uses these groups in a Box-Behnken experimental design to create a screening model most applicable to candidate Gulf Coast reservoirs (Box and Behnken 1960). By generating oil recovery and CO2 storage curves, the model estimates the cumulative oil recovery and CO2 storage potential for a given reservoir. Past screening models—Rivas et al. (1992) and Diaz et al. (1996)—focused only on oil recovery and simply assigned qualitative rankings to reservoirs. Models that did include quantitative results, including CO2 Prophet (Dobitz and Prieditis 1994) and the CO2 Predictive Model (Paul et al. 1984), did not include the effects of dip. This model focuses on both oil recovery and CO2 storage potential, produces quantitative results for each, and includes the effects ofdip.This model quickly estimates the oil recovery and CO2 storage potential for a reservoir. Operators can quickly screen large databases ofreservoirs to identify the best candidates for CO2 flooding and storage. The scaling groups also provide the basis for future models that may be more specific to other regions.The results show that continuous CO2 flooding can be fully described using 10 dimensionless groups: aspect ratio, dip angle group, water and CO2 mobility ratios, buoyancy number, dimensionless injection and producing pressures, residual oil saturation to water and gas, and initial oil saturation. The effects ofcapillary forces and dispersion were secondary effects in this model and were not included in the scaling. Dimensionless oil recovery was effectively modeled with the dimensionless oil breakthrough time and the dimensionless recovery at three different dimensionless times, while CO2 storage potential was calculated only at the final dimensionless time. The reservoir-specific parameters discussed above were calculated from response surface fits. The scaling does not work as well at small buoyancy numbers; however, it is effective in the range of values typical of Gulf Coast reservoirs.
Downhole Fluid Analysis and Fluid-Comparison Algorithm as Aid to Reservoir Characterization
Authors: Venkataramanan Lalitha , Elshahawi Hani , McKinney Daniel , Flannery Matthew , Hashem Mohammed , Mullins Oliver C. 
Published: July 2008

Summary
In recent years, formation-sampling and formation-testing tools have provided a variety of new downhole optical measurements for downhole fluid analysis (DFA). DFA involves an in-situ measurement of optical absorption spectra used to compute properties such as hydrocarbon composition and gas/oil ratio (GOR). Abrupt changes in these fluid properties with depth may be markers for reservoir compartmentalization. However, hydrocarbon differences can be identified reliably only when the significance of uncertainties from measurement and the oil-based mud (OBM) filtrate have been taken into account. Recently, an algorithm called the fluid-comparison algorithm (FCA) was developed to address this issue.
The FCA propagates uncertainties in optical measurement and contamination into uncertainties in fluid properties, such as color, composition, and GOR. The output of the FCA is the probability that two fluids are statistically different. Real-time application of the FCA can optimize capture of downhole-fluid samples and generation of a continuous downhole-fluid log representing the fluid complexity in the reservoir. In addition, by identifying abrupt changes in fluid properties that occur with depth, the FCA may in some circumstances be an assay for reservoir compartmentalization.
In this paper, we briefly review the theory of the FCA. The strengths and limitations of the technique for an improved understanding of reservoir architecture and fluid complexities are presented in two case studies.
Reservoir Crude Oil Viscosity Estimation From Wireline NMR Measurements - Rajasthan, India
Authors: Zittel R. J. , Beliveau D. , O'Sullivan T. , Mohanty R. , Miles J. 
Published: July 2008

Summary
In 2004, the Mangala, Aishwariya, and Bhagyam fields were discovered in Rajasthan, India. In these high-permeability paraffinic reservoirs, viscosity is one of the main factors controlling performance. Pressure, volume, and temperature (PVT) data show areal and vertical variations in crude properties. Meter-by-meter geo-chemical core analyses corroborate vertical variations in oil composition. Continuous wireline measurements of nuclear magnetic resonance (NMR) properties and station NMR properties from wells drilled with both water-based muds (WBM) and synthetic oil-based muds (OBM) were also used to calculate a viscosity profile. This paper correlates results from all techniques and shows how NMR measurements can provide oil viscosity profiles in com-positionally complex pools.
Black-oil PVT samples typically test several meters of reservoir, while Rajasthan geochemical data are available at meter scale. NMR logs provide continuous data, and calibrated to PVT and geochemistry, they can provide the most detailed picture of in-situ viscosity variations.
Results were used to construct a detailed spatial description of the reservoir's in-situ oil viscosity. The NMR data helped to define a zone of biodegraded oil up to ∼25 m thick above the oil-water contact (OWC) and showed thin accumulations of higher-viscosity oil on top of minor shale layers within oil columns. The major conclusion is that detailed in-situ oil viscosity profiles can be developed from conventional wireline T2 measurements.
Modeling the Effect of Viscosity Ratio on Spontaneous Imbibition
Authors: Fischer Herbert , Wo Shaochang , Morrow Norman R. 
Published: July 2008

Summary
Spontaneous-imbibition data for Berea sandstone cores, which are very strongly wetted by the aqueous phase and initially 100% saturated with mineral oil, are reported for linear, radial, and allfaces-open boundary conditions. Oil viscosities were 4, 63, and 173 cp, and aqueous-phase viscosities ranged from 1 to 495 cp. Oil-/aqueous-phase-viscosity ratios were varied by more than four orders of magnitude (0.01 to 173.1). Near-linear relationships (with slopes close to one-half), between the frontal position and imbibition time on a log-log scale, were obtained for both linear and radial countercurrent flow. Behavior is consistent, with near piston-like displacement by the imbibing aqueous phase. The results are analyzed by a new mathematical model that accounts for countercurrent spontaneous imbibition with symmetrical flow patterns. The model assumes that saturation and permeabilities to counterflowing phases behind the front are constant and that any effect of local change in interfacial curvature with distance is negligible. The results from the model are used to extend scaling to include the measured effect of viscosity ratio for linear and radial flow. For the all-faces-open boundary condition, commonly used in core-analysis studies, oil recovery vs. imbibition time is estimated by a combination of spherical and radial flow. Consistently close agreement was obtained between experiments and behavior predicted by the model.
Success Story of a Waterflood Project in a Geologically Complex, High-Viscosity Oil Reservoir in a Major Brownfield in South Oman
Authors: Choudhuri Biswajit , Al-Rawahi Mahir S. 
Published: July 2008

SummaryThis paper presents the success story of waterflooding in a geologically complex reservoir that contains high-viscosity (90 cp) oil. This reservoir is part of a large brownfield in south Oman and has been on production for more than 25 years. The reservoir comprises glacial sandstones of Palaeozoic age and is highly heterogeneous, with wide variation in reservoir characteristics at scales smaller than well spacing. The reservoir geology is complicated because of the presence of faults and fractures.The reservoir has been subdivided into different areas that we call "catchments," characterized by their geological setting and dynamic reservoir behavior. Full-field water injection was started in the field after approximately 18 years of primary depletion. Different water-injection philosophies for different areas of the field have been adopted with consideration to factors such as primary drive mechanism operative in the reservoir, presence or absence of vertical-flow barriers; pre-existing field-development pattern; and more importantly, future development beyond waterflood to maximize the value of the reservoir in its entire life cycle.The paper illustrates that the success of a waterflood in a complex reservoir relies on the implementation of a tailor-made development plan with flexibility to be changed on the basis of data from reservoir surveillance. The importance of well and reservoir management (WRM) to improve the value of waterflood is emphasized.
Controlling Water Production Using Gelled Polymer Systems
Authors: Willhite G. P. , Pancake R. E. 
Published: July 2008

Summary
Arbuckle reservoirs in central Kansas produce by natural water-drive. Although clean oil is usually produced on initial completion of a well, the water cut increases with time. Water cuts of 99% and water production rates of 400 to 3,000 B/D are common. Wells cannot be pumped off. Water production has been reduced selectively by treating wells with a chrome acetate-polyacrylamide gelant. In most cases, incremental oil is produced following the treatment. This paper describes results from a seven-well program in which production wells were treated with chrome acetate-polyacrylamide gelant. Pressure data were obtained before the treatment, during the gel treatment and after gel treatment. Buildup data were interpreted to estimate kh before the treatment, and the extent of permeability reduction to oil and water caused by the treatment. Bottomhole-pressure (BHP) data obtained during the treatment provided were used to monitor gelant placement. Production data following the treatments were analyzed to determine incremental oil production and correlate the treatments to the production response. Water-production rates were reduced in every well, and reductions were persistent during intervals ranging from 7 to 36 months. Incremental oil was produced in four of seven wells treated in the program. The amount of incremental oil increased with volume of gelant injected in wells with openhole completions. Results of this test program suggest how to distinguish wells that are likely to take large treatments from those that can be treated only with small amounts of gelant. These results should improve treatment design and identify wells that are good candidates for successful treatment.
A Semianalytic Model for the Productivity Testing of Multiple Wells
Authors: Fokker Peter A. , Verga Francesca 
Published: July 2008

SummaryWe present a semianalytic method for modeling the productivity testing of vertical, horizontal, slanted, or multilateral wells. The method is applicable to both oil and gas reservoirs and automatically accounts for well interference. The use of analytic expressions ensures that short-time transient behavior and long-time semisteady-state behavior are handled appropriately, whether close to the well or further into the reservoir. Calculation times are still very limited—on the order of a few minutes to a few seconds when all wells are vertical. This makes the tool suitable for evaluating well testing and determining well productivity.We based the approach on an earlier derived productivity prediction tool, in which the steady-state equations were solved. It has now been extended to solve the time-dependent diffusion equation. In our current method, the equations have first been transformed using the Laplace transformation. The expressions for the producing wells are combined with auxiliary sources outside the reservoir. The crux of the semianalytic method involves an adjustment of the positions and strengths of these sources in order to approximate the boundary conditions at the reservoir boundaries. The solution obtained is transformed back into the time domain by use of a Stehfest algorithm.The new approach has been validated with numeric tools, including both reservoir simulators and well-test interpretation software. Validations were performed with artificial cases and with field production data, using both single-well and multiple-well production tests. The results of these tests were excellent.
A Survey of North Sea Enhanced-Oil-Recovery Projects Initiated During the Years 1975 to 2005
Authors: Awan A. R. , Teigland R. , Kleppe J. 
Published: July 2008

Summary
This paper provides a summary and a guide of the enhanced-oil-recovery (EOR) technologies initiated in the North Sea in the period from 1975 until beginning of 2005. The five EOR technologies that have been initiated in this region are hydrocarbon (HC) miscible gas injection, water-alternating-gas (WAG) injection injection, simultaneous water-and-gas (SWAG) injection, foam-assisted WAG (FAWAG) injection, and microbial EOR (MEOR). Each EOR technology that has been initiated in the North Sea was identified with its respective maturity level and/or maturation time frame, technology use restrictions, and process efficiency on the basis of incremental oil.
Apart from WAG at Ekofisk and FAWAG at Snorre central fault block (CFB), all technologies have been applied successfully (i.e., positive in economic terms) to the associated fields. HC miscible gas injection and WAG injection can be considered mature technologies in the North Sea. The most commonly used EOR technology in the North Sea has been WAG, and it is recognized as the most successful EOR technology.
The main problems experienced were injectivity (WAG, SWAG, and FAWAG projects), injection system monitoring, and reservoir heterogeneities (HC miscible gas injection, WAG, SWAG, and FAWAG projects). Approximately 63% of all the reported EOR field applications have been initiated on the Norwegian continental shelf (NCS), 32% on the UK continental shelf, and the remainder on the Danish continental shelf. Statoil has been the leader in conducting EOR field applications in the North Sea. The majority of future research will concentrate on microbial processes, CO2 injection, and WAG (including SWAG) injection schemes.
In this review, laboratory techniques, global statistics, simulation tools, and economical evaluation were not considered and are considered outside of the scope of this paper.