bluuebunny/crossref_metadata_2025 huggingface dataset:
Well Integrity Management at Premier Oil and the Benefits of Implementing a Well Integrity Data Management System
Authors: Gell C. , Dawson M. , Emslie M. , Cruickshank B. , Fairnie N.
Published: April 2015

Like most companies today, Premier Oil (Premier) have been developing a Well Integrity Management System (WIMS) in order to provide a broader insight into both surface and subsurface well integrity issues. In addition to evolving their WIMS policies and procedures, Premier also chose to implement an effective and integrated well integrity data management software system to improve safety and operational efficiencies in the field, to increase production through reduction of well shut-in times, and to create a positive and proactive culture of managing well integrity which would allow Premier to proactively monitor and manage well integrity issues. This paper focuses on the reasons for implementing a well integrity management software system, the benefits to Premier by implementing the system, and how the system is used across all of Premier's assets.

Premier started by collecting and collating data to understand whether or not a well was operating within its safe operating limits, this included information from other applications to fully understand the well integrity picture. From that, a database of the wells was set up, wellhead templates created, test types and data input forms generated, and incorporation of Premier's WIMS policies and procedures into the application.

During the first year of implementation, the goal was to create a baseline of well integrity statuses for the current well stock and to establish workflows to manage the well integrity issues more effectively. The overall number of wells Premier operates is growing significantly with new and future developments, and hence this baseline establishment of good well integrity practices is preparing the company for future challenges and potential production concerns if well integrity issues arise.

Additionally, there were qualitative objectives:

– Improvement in the monitoring and managing integrity issues proactively; – Increased visibility of well integrity management within and outside the company; – Ease of accessing all of the well integrity information and analyzing that data to find and fix problems; – Improvement to data accuracy and availability to increase productivity by having up-to-date knowledge of well integrity issues.

To-date, Premier has already seen an improvement in understanding well integrity issues across all their assets. Prior to implementation of the new software, data was stored on spreadsheets with only key personnel involved and understanding integrity issues. Now a more informed group recieve quick notification when wells are operating outside their agreed parameters, which has led to an overall improvement in proactively managing well integrity issues. Additionally, Premier also expects a more stringent regulatory environment in the future, at which time the existing spreadsheet-based system would no longer be workable or acceptable to external authorities.
Design Procedures for Marine Renewable Energy Foundations
Authors: Stevens Robert F. , Soosainathan Lawrence , Rahim Amir , Saue Morten , Gilbert Robert , Senanayake Asitha I. , Gerkus Hande , Rendon Erica , Wang Shin Tower , O'Connell Daniel P.
Published: April 2015

The Geotechnics Sub-Committee of the American Society of Civil Engineers (ASCE) Coasts, Oceans, Ports, and Rivers Institute (COPRI) Marine Renewable Energy (MRE) Committee is preparing a guide document for marine renewable energy foundations. That guide would use standard design codes for fixed foundations and mooring anchors in API RP 2GEO and DNV.

The static method of computing axial pile capacity described in API RP 2GEO (2011) is generally used to compute ultimate compressive and tensile capacities of pipe piles driven to a given penetration. Lateral soil resistance –pile deflection (p-y) data for clays and sands are usually developed using procedures proposed by Matlock (1970) and O'Neill and Murchison (1983), respectively, and outlined in API RP 2GEO (2011). Marine energy foundations are unique in several ways. Axial pile capacity computations are usually based on a reasonable lower bound, in contrast to the soil resistance to driving, which is based on a reasonable upper bound. For structures supporting wind turbines, however, underestimating (or overestimating) the soil stiffness could require a change in turbine operation and a loss of power production. Although the classical API method is recognized as an appropriately conservative design method for offshore pile foundations, a prediction method is more well suited for structures supporting wind turbines, such as the CPT-based methods for predicting pile capacity in granular soils presented in API RP 2GEO (2011). If a prediction method is used to compute the soil resistance to driving, the evaluation of pile drivability may be overly conservative. Ageing in both clay and sand should also be taken into account. Wind turbines are often supported on large diameter monopiles. The applicability of the p-y data for such large diameter piles needs to be verified. Finally, marine renewable energy generated by in-stream hydrokinetics, ocean thermal energy conversion, and wave energy converters may be floating devices usually anchored to the seafloor. There are uncertainties in the design and installation of these anchors, which become critical for large sustained tensile loads that may degrade due to creep and cyclic loading.
SS Marine Renewable Energy – Ocean Current Turbine Mooring Considerations
Authors: VanZwieten J.H. , Baxley W.E. , Alsenas G.M. , Meyer I. , Muglia M. , Lowcher C. , Bane J. , Gabr M. , He R. , Hudon T. , Stevens R. , Duerr A.E.S.
Published: April 2015

To assist in the development of mooring and foundation solutions for ocean current based electricity production, an overview of the resource and seafloor characteristics in three potential power production regions are presented. These regions are offshore Florida USA, North Carolina USA, and South Africa. Maximum measured flow speed off both the USA and South Africa were around 3.0 m/s and maximum temporally averaged energy densities were between 2.0 - 3.0 kW/m2. Water depths at considered locations range from 60-400 m, and bottom type varies greatly. Most evaluated locations contain occasional flow reversals and occasions when current speed approached 0.0 m/s (only locations near the core of the Gulfstream off SE Florida did not measure either event). While low current events are undesirable from energy production and mooring design perspectives, they might provide unique opportunities to install or maintain equipment.
Effective Collaboration with Government Stakeholders: Key to Successful Delivery of Bonga Northwest (BNW) Project
Authors: Uyanwune Joey , Okonkwo Uche , Ibunde Terkimbi , Oni Olatunji , Zakkah Silas
Published: April 2015

The Bonga North West Project (BNW) is the first subsea extension to the existing Bonga Main facility located offshore Nigeria in water depths ranging from 990m – 1170m. The license is operated under a production sharing agreement with the Nigerian National Petroleum Corporation (NNPC) by Shell Nigeria Exploration and Production Company Limited (SNEPCo) in partnership with Esso E&P Nigeria Ltd, Nigeria Agip Oil Company (NAOC) and Total E&P Nigeria. The execution of the BNW Project involved extensive interaction with diverse Stakeholders. Stakeholders are key enablers and critical to successful project delivery. BNW stakeholders included Venture Partners, Contractors, Government and non-governmental organizations. The Government Stakeholders have regulatory oversight on the project. The dynamics of project execution and its multi-dimensional challenges sometimes result in situations that put requirement for Government Stakeholder's endorsement on the critical path for the project. The BNW Project Team and Government Stakeholders addressed these challenges in a collaborative manner. Collaboration with Government Stakeholders enabled the Project Team to mitigate potential issues and capture opportunities that helped deliver the project within schedule, on cost, and with no cost recovery exposure after investment decision. All regulatory permits and consents of the Government were obtained per schedule.

Stakeholders have different drivers. The Stakeholder collaboration model enabled the BNW Project to identify these drivers early, leading to proactive resolution of potential issues and to capture opportunities. It encouraged a culture of openness and collaboration between the Project and the Stakeholders. Conscious and deliberate actions were taken to maintain the relationships and collaborative culture. Meaningful integration and involvement of the Stakeholders in the execution of the project was crucial for the establishment and effectiveness a desired collaborative environment. The “integrate and involve” component of the model included regular reporting to inform and update, frequent face to face engagements, and periodic site visit by Stakeholders at specific stages of work progress. In addition, integration of some of the Government Stakeholders staff into the project, at various stages, provided them with the opportunity for better understanding and appreciation of the project dynamics and drivers.

The BNW project has been recognized by the National Petroleum Investment Management Services (NAPIMS), a subsidiary of Nigerian National Petroleum Corporation (NNPC) - Government Concessionaire, as one of the best offshore projects to be executed in Nigeria.

This paper focuses on the pathway and model that were applied to develop and sustain a collaborative relationship with Government Stakeholders, thereby reducing non-technical risks and achieving the successful accomplishment of all project delivery promises.
Bonga North West (BNW) Project: Delivering Nigerian Local Content in a Brownfield Project
Authors: Okonkwo Uche , Uzoka Austin , Uyanwune Joey , Zuhumben Paul
Published: April 2015

The Bonga North West (BNW) Project is a brownfield subsea tie-back to the Bonga Main field, via existing subsea infrastructure. The license is operated under a production sharing agreement with the Nigerian National Petroleum Corporation (NNPC) by Shell Nigeria Exploration and Production Company Limited (SNEPCo) in partnership with ExxonMobil, Nigeria Agip Oil Company (NAOC) and Total. Shell Companies in Nigeria (SCiN) local content contracting strategy includes - growing existing contractors and developing new contractors / businesses; developing additional skills and competencies of the local workforce; capacity building and supporting the acquisition of technology by Nigerian businesses to maximize their participation.

The project was executed via four major work packages – Topsides, Subsea and Flowlines and Umbilicals. The Topsides contract was awarded to a wholly indigenous contractor, while the Subsea, Flowline and Umbilical contracts were awarded to the local subsidiaries of foreign contractors.

The Project employed extensive engagement with the Nigerian Content Development Monitoring Board (NCDMB), and alignment with contractors and other stakeholders during execution. Regular site visits and reviews by parties, internal and external to the Project were performed to ensure effective compliance and delivery. The Project was the first to have a contract executed under the Nigerian Oil and Gas Industry Content Development Act (NOGID), and was the first to obtain a “Certificate of Compliance”. The key lessons learnt on this project will enhance the ability of future projects to comply with the NOGID Act.

This paper examines the achievements in Nigerian Local Content Delivery (NCD) by the BNW Project, highlights the challenges and difficulties in delivering NCD on the project and how they were addressed. The key lessons learnt and opportunities for improving NCD delivery will also be covered.
Safe Handling and Disposal of Nanostructured Materials
Authors: Raja Pavan M. V. , Huynh Monica , Khabashesku Valery N.
Published: April 2015

Applications based on nanostructured materials have been increasing, not only in sectors such as medicine and electronics, but also in the oil and gas industry. Nanostructured materials are substances that contain at least one dimension in the nanometer-size regime, and can include nanoparticulate materials such as quantum dots, nanofibrous materials such as carbon nanotubes, and nanoporous material such as activated carbon. In addition, nanomaterials can be as-received/produced or subsequently functionalized with a wide range of chemical species. Further, distinctions must be drawn between naturally occurring and/or biodegradable nanostructured materials and synthetic nanomaterials. The latter need more scrutiny, because they may not be in equilibrium with their environment. For example, non-biodegradable nanomaterials could accumulate in the tissues and organs of human beings, animals, and plant/trees with unknown long-term consequences.

Although use of nanomaterials in the oil and gas industry is still not widespread, potential applications of these novel materials include: waste water treatment, antimicrobial additives, multifunctional coatings, etc. These applications cause concerns regarding their safe handling and disposal, whether in the downhole environment or at the surface.

In this paper we provide a first-hand perspective about the appropriate handling of nanomaterials in a laboratory setting, coupled with a review of the related literature currently available. Such a perspective helps define guidelines for the safe implementation of nanomaterial-related technologies in the downhole setting, because the day is not far off when the industry will use these new materials extensively in the oilfield. In general, existing good laboratory practices apply and can serve as a foundation for developing methods to handle nanomaterials with enhanced safety features. Personal protective equipment and deliberate, planned actions need to be combined with some specific control measures to ensure safety. Some of these measures include waste minimization, specialized containments, and the control of nanoparticulate aerosols. And finally, compliance is important in terms of evolving regulations in the nanomaterials arena.

Nanosafety need not be an ambiguous concept as long as the personnel are well trained and informed about the properties of the materials they are handling. The experience shared in this paper can be applied to the safe handling and disposal of nanomaterials in general, and in any industrial, institutional, or academic setting.
Development and Qualification of a Tandem FLNG Loading Terminal for Conventional LNG Carriers
Authors: Hellesmark Svein B. , Andersen Per Gunnar , Thorsen Tord Broms
Published: April 2015

The first floating LNG (FLNG) projects are now in construction (Shell Prelude FLNG, Petronas FLNG and others) and more than 25 new FLNG projects are currently being planned World-wide. One of the most critical system for the overall safe and reliable operation of an FLNG is the LNG offloading system. The preferred option for most of the operators is to perform offloading in a tandem configuration. The challenge with such a solution is that it will normally require expensive dedicated LNG ships with DP (Dynamic Positioning) and LNG Bow Loading Systems.

This paper is describing the development and qualification of a tandem LNG offloading solution that solves this industry challenge. A dynamically positioned LNG Loading Terminal has been developed to enable a safe and reliable LNG transfer operation from a FLNG to any conventional LNG Carrier (LNGC) without any modification to the LNG ships.
Assessment of Pressurized Foamed Cement Used in Deep Offshore Wells
Authors: Kutchko Barbara , Crandall Dustin , Moore Johnathan , Gieger Connor , Gill Magdalena , Haljasmaa Igor , Spaulding Richard , Harbert William , Mergaman Alison , Dalton Laura , Rosenbaum Eilis , Mcintyre Dustin , Benge Glen , Buford Charles , Shine Joe
Published: April 2015

The National Energy Technology Laboratory (NETL) in conjunction with industry partners began a project to assess field-generated foamed cement at pressurized surface conditions. The collected samples were compared to previous field-generated samples as well as equivalent samples generated with current laboratory protocols following the recommended practices in American Petroleum Institute's Recommended Practice (API RP) 10B-4; atmospherically generated. In-situ samples of foamed cement were successfully captured in constant pressure (CP) cylinders under field conditions and analyzed while under pressure using multi-scale computed tomography (CT) scanning. The comparison of laboratory and field samples addresses changes to the cement under in situ conditions. Initial results highlight key differences in laboratory and field-generated foamed cements. Results of laboratory testing indicate a correlation between bubble size distribution, permeability, and strength. Field-generated samples show changes in pressure significantly influence the bubble size, while the flow of the slurry into the pressure cylinders created less homogeneous cured foamed cement. This paper discusses further research of in-situ field generated foamed cement behavior. These data provides insight to support the ongoing effort to help predict a method to correlate testing for foamed cement performance in the laboratory that would compare to more representative field behaviors.
Autonomous Underwater Vehicle Collaborations to Improve Hurricane Forecasting and Environmental Monitoring in the Gulf of Mexico
Authors: Perry Ruth , McCall Walt , Leung Pak Tao , Martin Kevin , Vandermeulen Ryan , Sharma Neha , Watson Stephanie , Howden Stephan , Kirkpatrick RBarb , Satterlee Kent , Vogel Michael , Brzuzy Louis , Voparil Ian , Raye Robert , Abadie Randall
Published: April 2015

Shell Exploration and Production Company is working with academic, non-profit, and federal stakeholders in the Gulf of Mexico to develop and implement long term environmental monitoring programs. One such program uses autonomous underwater gliders to provide near real-time oceanographic data to improve the understanding of the offshore physical environment and to improve estimates of upper ocean heat content for enhanced hurricane prediction and forecast models. Established in 2008, through a Memorandum of Agreement between Shell and NOAA, this partnership leverages the strengths of each collaborator to build a comprehensive and sustainable data collection system for providing real-time high resolution and baseline data to better assess environmental conditions and assure the environmental sustainability of Shell's activities in the Gulf of Mexico. An important element of the collaboration includes sharing data and results with the broader Gulf of Mexico stakeholder community. In this paper, we present the program framework, data and findings from three years of data collection (2012 — 2014), and identify future opportunities to leverage autonomous underwater gliders to improve understanding of the Gulf of Mexico offshore environment.
Terminal and Transportation Risk Assessment for LNG Export in North America
Authors: Hamedifar H. , Spitzenberger C. , Stahl C , Brown A , Nilberg B , Demay V. , Aspholm O.
Published: April 2015

This paper gives an overview of method development in quantitative risk analysis for marine terminals and transportation that have been applied to several of the planned LNG and LPG transportation projects in North America.

The growth in natural gas production in North America has renewed interest in exporting natural gas, mostly in the form of LNG or LPG. However, this growth comes with transportation challenges as suppliers, and operators move products and equipment, to and from an expanding number of sites (many of them in remote locations). Maintenance of safety and security practices is increasingly important as operations become geographically dispersed and more diverse. Analyses of reliability and risk are potentially most valuable during the early stages of marine terminal projects in guiding the decision on siting, design, and operative risk controls to reduce the risk as low as reasonably practical in final development.

An important development in quantitative risk analysis for marine transport is the ability to utilize "big data" resources like Automatic Identification System (AIS) tracking. Utilizing AIS data provides the best available picture of existing traffic in a waterway. Quantitative risk analysis applies historical data as the basis for estimating risk of future accidents. This paper gives examples of how to combine historical data and advanced failure mode modeling to better estimate risk for loss of containment from LNG and LPG carriers.

Quantification of accidental release frequencies and consequences of a release are demonstrated in this paper. The risk level for gas terminals and transportation area expressed in terms of individual risk at the terminal and along the transportation route. Newly developed methods make it possible to show the risk along the sailing route, accounting for the variation in traffic and environmental parameters along the route. Understanding of the key drivers of risk is important for the decision-makers to establish adequate risk controls for new energy export projects.
Lucius Spar: Design to Delivery
Authors: Tule J.
Published: April 2015

This paper provides an overview of the design and installation of Anadarko’s Lucius Truss Spar. This spar is the seventh spar designed and delivered in the operator’s fleet of offshore production facilities.

The design and engineering of the spar and mooring systems were performed using the most current environmental and regulatory requirements for floating facilities. The spar hull was fabricated in Finland and traveled to the gulf coast by dry transport. There it was outfitted and then wet towed to Keathley Canyon Block 875 in preparation for upending and mooring installation in 7,100 ft of water. The offshore campaign for the installation of the hull and mooring system was successfully completed in October of 2013 in preparation for the Topsides set in February of 2014.

This paper will summarize the design and fabrication of the Lucius spar as well as explore the project challenges for the delivery and installation of the facility, with special attention given to the issue of safety. The Lucius Spar is the operator’s largest spar to date and uses the latest technology to moor the hull in very challenging terrain. The installation contractor for the hull and mooring system, provided extensive engineering and project management to plan and execute the installation safely.
Offshore Wind Farm Case Study - How to Achieve Cost Reduction at Offshore Wind Farm Construction Projects
Authors: Cairney Jale
Published: April 2015

Brief Abstract

Offshore Wind Farm projects are growing in complexity with deeper water installations and larger scale designs. We have been accumulating knowledge and best practice in designing and building offshore wind farms, hence we are getting better at managing mega projects with offshore challenges. With the ABS Group case study, we will share offshore wind farm construction lessons learned and address where and how cost savings can be achieved without compromising quality and project schedule within the project execution practices.
A New Approach to History Matching Using Reservoir Characterization and Reservoir Simulation Integrated Studies
Authors: Avansi G.D. , Schiozer D.J.
Published: April 2015

Reservoir characterization is very important to the success of a history matching and production forecasting. Thus, numerical simulation becomes a powerful tool for the reservoir engineer in quantifying the impact of uncertainties in field development and management planning, calibrating a model with history data and forecasting field production, resulting in a reliable numerical model. History matching has been integrated into several areas, such as geology (geological characterization and petrophysical attributes), geophysics (4D seismic data), statistical approaches (Bayesian theory and Markov field), and computer science (evolutionary algorithms). Although most integrated history-matching studies use a unique objective function (OF), this is not enough. A history matching by simultaneous calibrations of different OF is necessary because all wells must have their OF near the acceptance range as well as maintain the consistency of generated geological models during reservoir characterization. The main goal of this work is to integrate history matching and reservoir characterization; applying a simultaneous calibration of different OF in a history matching procedure and keeping the geological consistency in an adjustment approach to reliably forecast production. We also integrate virtual wells and geostatistical methods into the reservoir characterization to ensure realistic geomodels without creating the geological discontinuities to match the reservoir numerical model. The proposed integrated calibration methodology consists of using a geostatistical method for modelling the spatial reservoir property distribution based on the well log data, running a numerical simulator and adjusting conditional realizations (models) based on geological modeling (variogram model, vertical proportion curve and regularized well log data) and reservoir uncertainties, using a simultaneous adjustment of different OF to evaluate the history matching process and virtual wells to perturb geological continuities such as channels and barriers. In conclusion, we present an effective methodology to preserve the consistency of geological models during history matching process. In addition, we simultaneously combine different OF to calibrate and validate the models with well production data. Reliable numerical and geological models are used in the forecasting production under uncertainties to validate the integrated procedure.
Performance Standards: Bridging the Gap between Safety Cases and Safety Critical Equipment
Authors: Schwartz T. , Fix H.
Published: April 2015

The pressure to operate safely in risk-sensitive industries such as oil and gas is always present, with many offshore drillers still struggling to define and practice effective safety-driven maintenance principles on a routine basis, given the dynamic and inherently dangerous nature of drilling hazards. This has given rise to the concept of establishing a performance-based approach to safety to directly tie global and regulatory standards to preventive maintenance tasks in the form of performance standards.
Numerical Simulation of Rollover in Floating LNG
Authors: Srinivasan Vedanth , Rahumathulla Lubeena , Joshi Shital , Lee Jeongwon
Published: April 2015

In handling Floating LNG storage and transportation, the rollover phenomena, referred to the spontaneous mixing of stratified LNG layers leading to increased LNG boil off rates, is one of the major safety concerns in LNG storage tanks. Stratification occurs when the LNG in the tank forms in different layers with different densities and temperatures. Heat leaks through the tank insulation leads to sudden mixing of these various density layers. This causes a sudden release of large amount of vapor and over pressurization of the tank leading to tank damage and failure. In FLNGs, the motion of the cargo can advance the boil off rates further.

A Computational Fluid Dynamics (CFD) model is proposed to capture the rollover phenomenon and its impact on boil off rate under static LNG conditions. The CFD model is first validated against experimental data for density distribution and is subsequently used to conduct a series of CFD studies to evaluate the rollover in different operating pressure conditions inclusive of heat leakage through wall. The study involves a fully thermodynamics and phase change coupled multiphase model accounting for the presence of multi-component system and is used to predict the boil off rate during a rollover occurrence in a static storage tank.

CFD analysis provides a comprehensive time dependent mixing behavior, inclusive of flow, density temperature distributions and mass transfer effects, of an LNG system under different conditions of feed rate, thermal gradients and storage pressure. In particular, with rollover event, the sudden change in density variations and boil off rates are captured.

There were many accidents reported in the LNG plants due to rollover. Different methods exist to monitor and prevent the rollover such as equipment installation to promote mixing, avoiding long stoppage time etc. The proposed CFD model can model the rollover phenomenon accurately while being able to predict the feasibility and efficiency of various rollover prevention methods.
IS THE INCIDENCE TREND OF HEPARIN-INDUCED THROMBOCYTOPENIA DECREASED BY THE INCREASED USE OF LOW-MOLECULAR-WEIGHT-HEPARIN?
Authors: Al-Eidan Fahad
Published: April 2015

Background: The increasing trend of using low-molecular-weight-heparin (LMWH) versus unfractionated heparin (UFH) in hospitalized adult patients is raising concerns about the incidence of heparin-induced thrombocytopenia (HIT). Method: A retrospective study analyzed the requests for heparin-induced antibodies by enzyme-linked immunosorbent assay (ELISA) among adult hospitalized patients during the period from January 2011 to December 2013. These patients received either UFH or LMWH for prevention or therapeutic indications. Those with positive immune-mediated HIT were identified and considered as case patients. Result: The usage of LMWH and UFH and development of HIT was determined during the study period. The incidence of HIT in patients receiving UFH and those receiving LMWH was 4.09 per thousand patients and 0.48 per thousand patients, respectively, (p<0.0001) with an overall incidence of 2.49 per thousand patients. Conclusion: The increased trend of using LMWH over UFH among hospitalized adult patients was observed and can be said to contribute to the diminished overall incidence of HIT.
An unusual cause of anemia and encephalopathy
Authors: Sharma Sanjeev Kumar , Choudhary Dharma , Handoo Anil , Dhamija Gaurav , Kharya Gaurav , Khandelwal Vipin , Dhamija Mayank , Kothari Sweta
Published: April 2015

The authors present here an interesting case of recent onset anemia that was associated with an encephalopathy of the unusual cause.Although severe anemia can theoretically result in anemic hypoxia and can then lead to hypoxic encephalopathy, it is not a primary cause of encephalopathy. More frequently anemia can contribute together with other multiple causes of encephalopathy, such as infections, metabolic abnormalities, trauma, hepatic dysfunction, hypertension, toxins.
Polyol pathway: A possible mechanism of diabetes complications in the eye
Authors: Mathebula Solani D.
Published: April 2015

In complex diseases such as diabetes mellitus, the causative agents include various serum factors such as glucose, aldose reductase, oxygen-free radicals, advanced glycation end products, protein kinase-C and growth factors. The polyol pathway is a pathway of glucose metabolism and is regarded as an important element in the pathogenesis of refractive changes, cataract formation and diabetic retinopathy in individuals with diabetes mellitus. The focus of this review is on the role of the polyol pathway in the pathogenesis of diabetic complications in the eye. The first enzyme (aldose reductase) in the polyol pathway reduces glucose to sorbitol. The second enzyme (sorbitol dehydrogenase) converts sorbitol to fructose. The accumulation of sorbitol and fructose in the crystalline lens and retina leads to the generation of oxidative stress. Oxidative stress is the imbalance between levels of reactive oxygen species and the antioxidant defence in a biological system, and it results in tissue damage. How hyperglycaemia leads to oxidative stress is not clear but could be through a combination of increased levels of reactive oxygen species and decreased capacity of the cellular antioxidant system. Oxidative stress causes the development of diabetic complications that are seen clinically.
What hope is there for South Africa? A public theological reflection on the role of the church as a bearer of hope for the future
Authors: Forster Dion A.
Published: April 2015

What hope is there for South Africa? What role can the church play as a bearer of hope in South Africa? This article seeks to address these important questions. Firstly, it problematises the contemporary notion of hope in South Africa by showing that it is a complex theological and social concept. Next, a nuanced understanding of hope is presented by adopting a public theological methodology that brings dominant theological perspectives on eschatological hope into dialogue with the most recent statistics about the quality of life in South Africa from 1994, 2004 and 2014. The article proposes that the complexity of Christian hope necessitates an understanding of the present reality that is held in dynamic tension with the desired future – namely a present-futurist eschatology. Finally the article shows that from this vantage point the church, in its various forms and understandings, is able to be a bearer of Christian hope that can contribute towards shaping a better future for South Africa.
Cytological variations and typical diagnostic features of endocervical adenocarcinomain situ: A retrospective study of 74 cases
Authors: Umezawa Takashi , Umemori Miyaka , Horiguchi Ayana , Nomura Kouichi , Takahashi Hiroyuki , Yamada Kyosuke , Ochiai Kazunori , Okamoto Aikou , Ikegami Masahiro , Sawabe Motoji
Published: April 2015

Background:

The sensitivity of Papanicolaou smears for detecting endocervical adenocarcinomain situ(AIS) is very low. A comprehensive cytological analysis of endocervical AIS is necessary to increase diagnostic accuracy.

Methods:

The subjects were 74 patients with pathologically-diagnosed AIS. A total of 140 Papanicolaou smears were reviewed to calculate the sensitivity of the Papanicolaou smears for detecting AIS and the incidence of sampling/screening/diagnostic errors. The cytological review was performed by 6 cytotechnologists, and the final cytological diagnosis was obtained at the consensus meeting. We classified the cases into three differentiation types; typical type (well-differentiated AIS), polymorphic type (poorly differentiated AIS), and mixed typical and polymorphic type. Three cytological subtypes (endocervical, endometrioid and intestinal subtypes) of AIS were also analyzed.

Results:

The sensitivity of the original Papanicolaou smears for the detection of AIS was 44.6%, while that for the detection of AIS and adenocarcinoma was 63.5%. The diagnostic accuracy of AIS increased to 78.5% in the final diagnosis. The common characteristic features were microbiopsies/hyperchromatic crowded groups (HCG) (82.0%) and mitotic figures (72.2%). The appearance of single cells (2.8%) was rare, and all the cervical cytology smears showed no evidence of necrotic tumor diathesis. The most common AIS was the typical type (41 cases, 67.2%) among all cytologically-diagnosed AIS or adenocarcinoma cases (61 cases). Although mixed typical and polymorphic AIS existed in 17 cases (27.9%), pure polymorphic AIS was very rare (3 cases, 4.9%). The endocervical subtype was the most predominant subtype (67.2%), followed by a few mixed subtypes. The important diagnostic keys for AIS cytology are as follows: (1) The appearance of microbiopsies/HCG (single-cell pattern is rare), (2) mitotic figures in the microbiopsies/HCG, (3) a lack of necrotic tumor diathesis in cases with polymorphic AIS, and (4) recognition of typical cytological subtypes.

Conclusions:

The relatively low diagnostic accuracy AIS was caused by the underestimation of microbiopsies/HCG and the overestimation of polymorphic components. The typical cytological features of AIS are the presence of microbiopsies/HCG with mitotic figures in the absence of necrotic tumor diathesis in specimens containing endocervical samples. The recognition of infrequent AIS subtypes (endometrioid and intestinal subtypes) is also important.
Reverse enGENEering of Regulatory Networks from Big Data: A Roadmap for Biologists
Authors: Dong Xiaoxi , Yambartsev Anatoly , Ramsey Stephen A. , Thomas Lina D , Shulzhenko Natalia , Morgun Andrey
Published: April 2015

Omics technologies enable unbiased investigation of biological systems through massively parallel sequence acquisition or molecular measurements, bringing the life sciences into the era of Big Data. A central challenge posed by such omics datasets is how to transform these data into biological knowledge, for example, how to use these data to answer questions such as: Which functional pathways are involved in cell differentiation? Which genes should we target to stop cancer? Network analysis is a powerful and general approach to solve this problem consisting of two fundamental stages, network reconstruction, and network interrogation. Here we provide an overview of network analysis including a step-by-step guide on how to perform and use this approach to investigate a biological question. In this guide, we also include the software packages that we and others employ for each of the steps of a network analysis workflow.
Mechanical Circulatory Support and the Role of LVADs in Heart Failure Therapy
Authors: McLarty Allison
Published: April 2015

Heart failure is epidemic in the United States with a prevalence of over 5 million. The diagnosis carries a mortality risk of 50% at 5 years rivaling many diagnoses of cancer. Heart transplantation, long the “gold standard” treatment for end stage heart failure unresponsive to maximal medical therapy falls way short of meeting the need with only about 2,000 transplants performed annually in the United States due to donor limitation. Left ventricular devices have emerged as a viable option for patients as both a “bridge to transplantation” and as a final “destination therapy”.
Roles of Solvent Accessibility and Gene Expression in Modeling Protein Sequence Evolution
Authors: Wang Kuangyu , Yu Shuhui , Ji Xiang , Lakner Clemens , Griffing Alexander , Thorne Jeffrey L.
Published: April 2015

Models of protein evolution tend to ignore functional constraints, although structural constraints are sometimes incorporated. Here we propose a probabilistic framework for codon substitution that evaluates joint effects of relative solvent accessibility (RSA), a structural constraint; and gene expression, a functional constraint. First, we explore the relationship between RSA and codon usage at the genomic scale as well as at the individual gene scale. Motivated by these results, we construct our framework by determining how probable is an amino acid, given RSA and gene expression, and then evaluating the relative probability of observing a codon compared to other synonymous codons. We come to the biologically plausible conclusion that both RSA and gene expression are related to amino acid frequencies, but, among synonymous codons, the relative probability of a particular codon is more closely related to gene expression than RSA. To illustrate the potential applications of our framework, we propose a new codon substitution model. Using this model, we obtain estimates of 27 N s, the product of effective population size N, and relative fitness difference of allele s. For a training data set consisting of human proteins with known structures and expression data, 2 N s is estimated separately for synonymous and nonsynonymous substitutions in each protein. We then contrast the patterns of synonymous and nonsynonymous 2 N s estimates across proteins while also taking gene expression levels of the proteins into account. We conclude that our 2 N s estimates are too concentrated around 0, and we discuss potential explanations for this lack of variability.
Density distribution of particles upon jamming after an avalanche in a 2D silo
Authors: Uñac Rodolfo O. , Sales José L. , Gargiulo María V. , Vidales Ana M.
Published: April 2015

We present a complete analysis of the density distribution of particles in a two dimensional silo after discharge. Simulations through a pseudo-dynamic algorithm are performed for filling and subsequent discharge of a plane silo. Particles are monosized hard disks deposited in the container and subjected to a tapping process for compaction. Then, a hole of a given size is open at the bottom of the silo and the discharge is triggered. After a clogging at the opening is produced, and equilibrium is restored, the final distribution of the remaining particles at the silo is analyzed by dividing the space into cells with different geometrical arrangements to visualize the way in which the density depression near the opening is propagated throughout the system. The different behavior as a function of the compaction degree is discussed.Received: 9 December 2014,  Accepted: 13 April 2015; Edited by: L. A. Pugnaloni; Reviewed by: F. Vivanco, Dpto. de Física, Universidad de Santiago de Chile, Chile; DOI: http://dx.doi.org/10.4279/PIP.070007Cite as: R. O. Uñac, J. L. Sales, M. V. Gargiulo, A. M. Vidales, Papers in Physics 7, 070007 (2015)This paper, by R. O. Uñac, J. L. Sales, M. V. Gargiulo, A. M. Vidales, is licensed under the Creative Commons Attribution License 3.0.
Evaluating the effects of China's pollution controls on inter-annual trends and uncertainties of atmospheric mercury emissions
Authors: Zhao Y. , Zhong H. , Zhang J. , Nielsen C. P.
Published: April 2015

Abstract. China's anthropogenic emissions of atmospheric mercury (Hg) are effectively constrained by national air pollution control and energy efficiency policies. In this study, improved methods, based on available data from domestic field measurements, are developed to quantify the benefits of Hg abatement by various emission control measures. Those measures include increased use of (1) flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems in power generation; (2) precalciner kilns with fabric filters (FF) in cement production; (3) mechanized coking ovens with electrostatic precipitators (ESP) in iron and steel production; and (4) advanced production technologies in nonferrous metal smelting. Investigation reveals declining trends in emission factors for each of these sources, which together drive a much slower growth of total Hg emissions than the growth of China's energy consumption and economy, from 679 metric tons (t) in 2005 to 750 t in 2012. In particular, estimated emissions from the above-mentioned four source types declined 3% from 2005 to 2012, which can be attributed to expanded deployment of technologies with higher energy efficiencies and air pollutant removal rates. Emissions from other anthropogenic sources are estimated to increase by 22% during the period. The species shares of total Hg emissions have been stable in recent years, with mass fractions of around 55, 39, and 6% for gaseous elemental Hg (Hg0), reactive gaseous mercury (Hg2+), and particle-bound mercury (Hgp), respectively. The higher estimate of total Hg emissions than previous inventories is supported by limited simulation of atmospheric chemistry and transport. With improved implementation of emission controls and energy saving, a 23% reduction in annual Hg emissions from 2012 to 2030, to below 600 t, is expected at the most. While growth in Hg emissions has been gradually constrained, uncertainties quantified by Monte Carlo simulation for recent years have increased, particularly for the power sector and particular industrial sources. The uncertainty (expressed as 95% confidence intervals) of Hg emissions from coal-fired power plants, for example, increased from −48–+73% in 2005 to −50–+89% in 2012. This is attributed mainly to increased penetration of advanced manufacturing and pollutant control technologies; the unclear operational status and relatively small sample sizes of field measurements of those processes have resulted in lower but highly varied emission factors. To reduce uncertainty and further confirm the benefits of pollution control and energy polices, therefore, systematic investigation of specific Hg pollution sources is recommended. The variability of temporal trends and spatial distributions of Hg emissions needs to be better tracked during the ongoing dramatic changes in China's economy, energy use, and air pollution status.
Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest
Authors: Kim S. , Kim S.-Y. , Lee M. , Shim H. , Wolfe G. M. , Guenther A. B. , He A. , Hong Y. , Han J.
Published: April 2015

Abstract. Rapid urbanization and economic development in East Asia in past decades has led to photochemical air pollution problems such as excess photochemical ozone and aerosol formation. Asian megacities such as Seoul, Tokyo, Shanghai, Guangzhou, and Beijing are surrounded by densely forested areas, and recent research has consistently demonstrated the importance of biogenic volatile organic compounds (VOCs) from vegetation in determining oxidation capacity in the suburban Asian megacity regions. Uncertainties in constraining tropospheric oxidation capacity, dominated by hydroxyl radical, undermine our ability to assess regional photochemical air pollution problems. We present an observational data set of CO, NOx, SO2, ozone, HONO, and VOCs (anthropogenic and biogenic) from Taehwa research forest (TRF) near the Seoul metropolitan area in early June 2012. The data show that TRF is influenced both by aged pollution and fresh biogenic volatile organic compound emissions. With the data set, we diagnose HOx (OH, HO2, and RO2) distributions calculated using the University of Washington chemical box model (UWCM v2.1) with near-explicit VOC oxidation mechanisms from MCM v3.2 (Master Chemical Mechanism). Uncertainty from unconstrained HONO sources and radical recycling processes highlighted in recent studies is examined using multiple model simulations with different model constraints. The results suggest that (1) different model simulation scenarios cause systematic differences in HOx distributions, especially OH levels (up to 2.5 times), and (2) radical destruction (HO2 + HO2 or HO2 + RO2) could be more efficient than radical recycling (RO2 + NO), especially in the afternoon. Implications of the uncertainties in radical chemistry are discussed with respect to ozone–VOC–NOx sensitivity and VOC oxidation product formation rates. Overall, the NOx limited regime is assessed except for the morning hours (8 a.m. to 12 p.m. local standard time), but the degree of sensitivity can significantly vary depending on the model scenarios. The model results also suggest that RO2 levels are positively correlated with oxygenated VOCs (OVOCs) production that is not routinely constrained by observations. These unconstrained OVOCs can cause higher-than-expected OH loss rates (missing OH reactivity) and secondary organic aerosol formation. The series of modeling experiments constrained by observations strongly urge observational constraint of the radical pool to enable precise understanding of regional photochemical pollution problems in the East Asian megacity region.