bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Oil Recovery (EOR) Status - Colombia
Authors: Castro R. , Maya G. , Mercado D. , Trujillo M. , Soto C. , Pérez H. , Lobo A. , Ordóñez A. , Sandoval J. E.
Published: December 2010

Secondary and tertiary oil recovery technologies are not a common practice in Colombia. There are only 23 secondary oil recovery applications in a commercial level, and tertiary projects are limited to pilots that for different reasons have not been taken to the next level and to steam injections projects (huff & puff) in some heavy oil fields. However, Colombian interest and knowledge about the topic is every time higher and there exist different registers about an important number of initiatives to laboratory level that included modeling tasks for specific fields.

This paper looks around the different EOR§ initiatives that have existed in Colombia, from laboratory to field scale; in the same way, the research activities that have been done in the Instituto Colombiano del Petróleo (I.C.P.) of ECOPETROL S.A. are highlighted, where an important percentage of the jobs have been done, and where the necessary tools for modeling and evaluating almost every process exist. There are also presented in this paper the actual efforts in EOR, identifying the technologies for which exist the highest attention and the number of projects in design stage.

From the material presented in this article it is possible to understand the EOR potential in Colombia, to identify the increasing interest in the subject, to recognize opportunities in the subject and to learn from the applications done until now.
Dina Cretáceos Field Chemical EOR: From Screening to Pilot Design
Authors: Sandoval J. R. , Pérez H. , Maya G. , Castro R. , Muñoz E. , Colmenares K. , León J. , Sánchez F. , Villadiego D. , Manrique E. , Romero J. , Izadi M.
Published: December 2010

Dina Cretaceous Field is located in the Upper Magdalena Valley (UMV) Basin, Colombia. Producing reservoir consist in a marine-transitional depositional environment with good sand continuity and thickness. Ecopetrol S.A operates the field. The field was discovered in 1969. Primary production peaked at 6,500 BOPD. Peripheral water injection started in 1985 reaching a maximum oil production rate of approximately 10,000 BOPD. Current recovery factor is estimated in 32% of the OOIP with water cuts of 96%. Water injection is operating under adverse mobility ratios (M > 4) due to crude oil viscosity (10.8 cp) at reservoir conditions.

As a strategy to increase oil recovery an integrated study started in October 2009. Main objective of the multidisciplinary group was to evaluate different IOR/EOR technologies, select the most promising technology and identify areas of the field suitable to implement a pilot project. First phase of the study was a comprehensive evaluation of injection-production history of the field and IOR/EOR screening. Simultaneously, the team was also focused on updating the history match of the field injection-production history. The numerical model was based on a high-resolution geological model with a detailed lithological and petrophysical description. Once a reasonable history match was achieved the model was converted into a commercial platform to simulate chemical EOR processes.

The analysis of injection-production history did not support strong water channeling due to the presence of thief zones. IOR/EOR screening results confirmed the feasibility of polymer-based technologies due to the adverse mobility ratios and remaining oil saturation in the reservoir. Reservoir analogs identified during the screening study, conceptual simulations and laboratory studies concluded that the injection of Colloidal Dispersion Gels (CDG) shows high potential to increase oil recoveries economically in Dina Field. A pilot area was selected ranking different options and operational constraints. Pilot project design scheduled for the last quarter of 2010 was based on a sector model of the field.

This study provides guidance to effectively evaluate and implement chemical EOR technologies to revitalize mature water floods. A proper decision framing, availability of data and commitment of management and decision makers are key elements to perform EOR evaluations and implementation is short periods of time.
Analysis of Mechanisms of Flow in Fractured Tight-Gas and Shale-Gas Reservoirs
Authors: Moridis G. J. , Blasingame T. A. , Freeman C. M.
Published: December 2010

In this paper we analyze by means of numerical simulation the mechanisms and processes of flow in two types of fractured tight gas reservoirs: shale and tight-sand systems. The numerical model includes Darcy's law as the basic equation of multi- phase flow and accurately describes the thermophysical properties of the reservoir fluids, but also incorporates other options that cover the spectrum of known physics that may be involved: non-Darcy flow, as described by a multi-phase extension of the Forschheimer equation that accounts for laminar, inertial and turbulent effects; stress-sensitive flow properties of the matrix and of the fractures, i.e., porosity, permeability, relative permeability and capillary pressure; gas slippage (Klinkenberg) effects; and, non-isothermal effects, accounting for the consequences of energy balance and temperature changes in the presence of phenomena such as Joule-Thompson cooling in the course of gas production. The flow and storage behavior of the fractured media (shale or tight sand) is represented by various options of the Multiple Interactive Continua (MINC) conceptual model, in addition to an Effective Continuum Method (ECM) option, and includes a gas sorption term that follows the Langmuir isotherm. Comparison to field data, analysis of the simulation results and parameter determination through history matching indicates that (a) the ECM model is incapable of describing the fractured system behavior, and (b) shale and tight-sand reservoirs exhibit different behavior that can be captured (albeit imperfectly) using some of the more complex options of the multi-continua fractured-system models. The sorption term is necessary to describe the behavior of shale gas reservoirs, and significant deviations from the field data are observed if it is omitted. Conversely, production data from tight-sand reservoirs can be adequately represented without accounting for gas sorption. All the other processes and mechanisms allow refinement of the match between predictions and observations, but appear to have second- order effects in the description of flow through fractured tight gas reservoirs.
Controlling Oil Production in Smart Wells by MPC Strategy with Reinforcement Learning
Authors: Talavera Alvaro Lopez , Túpac Y. J. , Vellasco Marley M.
Published: December 2010

This work presents the modeling and development of a methodology based on Model Predictive Control – MPC that uses a machine learning model, based on Reinforcement Learning, as the method for searching the optimal control policy, and a neural network as a proxy, for modeling the nonlinear plant. The neural network model was developed to predict the following variables: average pressure of the reservoir, the daily production of oil, gas, water and water cut in the production well, for three consecutive values, to perform the predictive control. This model is applied as a strategy to control the oil production in an oil reservoir with existing producer and injector wells. The experiments were carried out on a synthetic oil reservoir model that consists in a reservoir with three layers with different permeability and one producer well and one injector well, both completed in the three layers. There are three valves located into the injector well, one for each completion, which are the handling variables of the model. The oil production of the producer well is the controlled variable. The experiments performed have considered various set points and also the impact of disturbances on the production well. The obtained results indicate that the proposed model is capable of controlling oil production even with disturbances in the producing well, for different reference values for oil production and supporting some features of the petroleum reservoir systems such as: strong non- linearity, long delay in the system response, and multivariate characteristic.
Laboratory Development and Successful Field Application of a Conformance Polymer System for Low-, Medium-, and High-Temperature Applications
Authors: Vasquez J. , Eoff L.
Published: December 2010

This paper presents the laboratory development of an organically crosslinked polymer (OCP) system with a wide temperature range of execution (60 to 350°F). The OCP system is targeted to address conformance problems (water and gas shutoff) to ultimately improve hydrocarbon recovery. This paper presents an overview of case histories in which the OCP system was implemented in various regions of the world in onshore and offshore hydrocarbon-producing wells.

The OCP system has been successfully applied to sandstone, carbonate, and shale formations needing a conformance treatment. The OCP system has proven to be resistant to acid and stable in CO2 and H2S environments. In addition, the activation time and gel strength of the system is not affected by lithology, formation fluids, or heavy metals. The OCP system is acceptable to be used in some areas of the North Sea (including UK and Netherlands).

Recently, a base polymer (for low temperatures) and a retarder (for high temperatures) have been introduced to the system to allow a wider temperature range of applicability without compromising its effectiveness or thermal stability. With the new base polymer, reasonable gelation times (~4 to 6 hours) can be achieved at 60°F with low crosslinker loadings. In addition, the new retarder allows reasonable placement times up to 350°F, without the need of cooling down the formation to obtain enough pumping time. Neither the new base polymer nor the retarder are detrimental to the thermal stability or gel strength of the system.

To date, more than 600 jobs have been performed with the OCP system around the world to address conformance problems, such as water coning/cresting, high-permeability streaks, gravel-pack isolation, fracture shutoff, and/or casing leak repair. Because of the capability of the OCP system to withstand pressure, workover operations have been successfully performed in previously treated wells, including acid stimulation, sand control, and frac-pack treatments, among others. Case histories are presented for onshore and offshore applications.
Proposed Brazilian Fiscal System for Pre-Salt Production Projects: A Comparative Study of Gain and Loss of Government and Companies
Authors: Costa Lima G. A. , Gaspar Ravagnani A. T. , Schiozer D. J.
Published: December 2010

After the discovery of large oil reserves in pre-salt areas of Santos Basin, the Brazilian government has changed the fiscal regime from royalty/tax system to production sharing system, which is the one already adopted in countries like Indonesia, Colombia, among others. The proponents of this idea say that it is necessary, because after these discoveries the exploration risk in this area is low. The proposed fiscal regime has created an intense debate among professionals, institutions and government. Who will be the winner? Who will be the looser? How much will be the loss or gain? At this moment, there is not clear convergence of viewpoint about the forecasting of the impacts on new investment. The reason for the implementation of production sharing system is because government wishes to capture a larger share of the profits. How? Politicians believe that the following policy could bring more benefits to government: in the bidding to new productions projects, the winner will be the company that offers the largest share of production to government. Then, the main objective of this paper is to investigate the behavior of the proposed fiscal regime in terms of production profile, NPV and risk, etc. In order to carry out this study, first, a typical oil field project from the pre-salt area is selected, whose characteristics are: large reserve, located in deep-water and bellow salt layer. After that, it is carried out an economic evaluation, comparison and risk analysis of a production strategy considering both regimes of concession and production-sharing. It is concluded that, it is not always that production-sharing agreement is superior, since it depends on the share of government in production, investment level, operation cost, among others.
BC-10 Brazil: Successful Deepwater 3D ERD Directional-Drilling Strategy Using Seismic Inversion and Point-the-Bit Rotary-Steerable System
Authors: Stockwell L. , Zambrano S. , Bezerra F. , Arevalo Y.
Published: December 2010

The BC-10 project has installed an FPSO in some of the deepest waters worldwide. The well configurations include complex 3D profiles that kick off from vertical in a riserless top hole section very close to the seabed in an unconsolidated formation. In the intermediate hole, high turn and build rates are required for accurate landing at challenging targets close to horizontal. The asset is operated by Shell with a 50% interest with joint-venture partners Petrobras (35%) and ONGC (15%)

Complex lithology among interbedded shales, siltstones, and hard limestone layers generated different directional responses that required collaboration by Shell geology/drilling department and the Schlumberger drilling engineering team to gain a better understanding of the directional performance and formation response so that they could plan the correct drilling parameters and improve drilling performance.

Aggressive dog leg severity requirements for the top hole and buildup sections reaching up to 4.2°/100 ft could not be fully met in the initial three wells. For that reason, a change not only in drilling tool technology but also in the planning workflow process was required. Understanding the formation characteristics and anomalies by using seismic modeling software to interpret and extrapolate directional results to the wells being planned had played a key role in correlating formation tendencies with DLS, RSS capabilities, and drilling parameters performance.

The process consists of analyzing actual drilling parameters in the software (ROP, RSS ratio, DLS, drilling parameters) by correlating them with the respective lithology in the trajectory. The results form the basis of the design for planning subsequent sections to be drilled.

Steep performance improvements regarding DLS capabilities and drilling practices under different lithology tendency profiles enabled new benchmarks for technological limits and well complexity. The new technology and process achieved a step change in performance was achieved for surface sections that was proven in 11 sections drilled. Average days per 1,000 m dropped from 8 to 2.5 days for a savings of approximately USD 15 million.

The techniques developed, the directional results of this initial stage of the project, and the lessons learned are discussed. This new techniques has extended the potential of future ultradeep development projects. As a result, the innovative planning process is being considered in the design workflow for similar borehole profiles worldwide.
Influence of Non-parallel SAGD Well Pairs and Permeability Heterogeneities on Recovery Factors from Warm Heavy Oil Reservoirs
Authors: Bashbush Jose Luis , Pina Jose Antonio
Published: December 2010

A key component influencing the final recovery factor of a Steam Assisted Gravity Drainage (SAGD) well pattern is the correct well placement. The optimum spacing and position of the well pairs within the net pay is a function of in-situ oil viscosities, reservoir properties and heterogeneities defining the steam injectivity and the effective heat transfer within the reservoir.

The well design parameters are typically optimized with thermal reservoir simulators constructed considering that both injector and producer wells are parallel to themselves, to the formation boundaries and with the well-pairs aligned throughout their entire length. However, due to various operational realities including the precision of the guiding tools that navigate the wells, actual SAGD well pairs in the field are seldom drilled perfectly parallel.

The study was directed to wells drilled in thick, heavy oil reservoirs where the combination of very high permeabilities of poorly consolidated sands and reservoir temperatures higher than about 30 °C [86 °F] have the ability to flow cold at reasonable oil rates in spite of having in-situ oil viscosities in the thousands of centipoises.

This paper expands the previous work of the authors (2010) analyzing the fact that wells from a SAGD pair in the field are not likely to be precisely parallel and quantifies the effects that this lack of exact parallelism brings to the production rates and overall recovery factors comparing them to the recovery variations that result from small to moderate reservoir heterogeneities.
Integrated Project Management Applied in World-Class Gas-Field Development Projects: From Theory to Practice
Authors: Safra Eduardo Bazo , Antelo Sergio Barrios
Published: December 2010

Stage Gate Project Management Process (SGPMP) is a methodology that has been widely used by many important Oil & Gas companies worldwide. SGPMP aims to improve the decision-making process in Project and Portfolio Management by helping to manage the levels of uncertainty and increase the quality of the projects.

The goal is not the elimination of uncertainties, but to make the best decision in a rational and systematic manner for managing the uncertainties and the associated risks that will always exist in any project.

This document will analyze the application of the SGPMP methodology used to manage and control two world-class gas-field development projects in Peru and Bolivia. It takes into account that the decision whether or not to continue with the project is related to factors such as cost-benefit ratio, risks, funds availability, human resources, as well as project alignment with strategic business objectives.

Implementation of this approach was a challenge, as it was one of the company's first experiences using SGPMP. This experience was a learning process to adapt project management theory into practice.

This paper will be useful for those Project Managers who are considering implementing a methodology similar to SGPMP in their Oil and Gas development projects. It provides key insights about value improvement practices and lessons learned by the authors from the early stages of the projects.

Conclusions and opinions expressed herein are those of the authors and not necessarily those of the company.
Optimization of Completions in Unconventional Reservoirs for Ultimate Recovery
Authors: Snyder Daniel J. , Seale Rocky , Hollingsworth Robert
Published: December 2010

Over the last decade, an industry wide shift to unconventional plays has occurred due to advances in technology allowing for the recovery of previously uneconomic reserves. The primary objective of completions in these unconventional reservoirs is to increase the effective surface area of the well to maximize reservoir contact. Horizontal drilling and multi-stage fracturing are two technologies which have accomplished this.

The two main methods of horizontal, multi-stage completions currently used in unconventional reservoirs are: cemented liner "plug and perf" and open hole, multi-stage fracturing systems. This paper provides an introduction to unconventional reservoirs, describes the main methods of horizontal, multi-stage completions, and discusses how the choice of method can affect good fracturing practices as well as long-term production. Case study examples are presented from a variety of unconventional reservoirs including shale, tight sandstone and tight dolomite formations.

Operators working in a number of unconventional reservoirs, such as shales and other tight rock formations are experiencing faster than expected production decline rates, resulting in reduced long-term, ultimate recovery. This may be in part due to the abandonment of good fracturing practices, developed over the past 50 years, with the advent of horizontal, multi-stage fracturing. Issues such as near wellbore conductivity, flowback, and fracture tortuosity that can have a significant effect on the long-term production of wells need to be considered when choosing a completion method, particularly for unconventional reservoirs.

Unconventional plays are becoming a significant part of the oil industry today and will become a bigger part in the future. It is important that the reservoirs are completed optimally to achieve maximum recovery. The information provided in this paper is applicable to unconventional resource plays worldwide.
Integrated Sand-Production Management in a Heterogeneous and Multilayer Mature Field with Water Injection
Authors: Nunez G. , Amaya M. , Hernandez J. , Agudelo O.
Published: December 2010

Casabe Field since the beginning of primary stage presented sand production problem because the producers are opened with different multilayer and heterogeneous unconsolidated sandstone. Additionally in the first stage of waterflooding project the use of gravel pack was implemented to control sand production, but it generated a large fall down in production due to the mechanical damage, which caused re-pressurization in certain area and drop down injection rate. At the end oil recovery was too low and sweep efficiency very poor.

In the current stage, at first, the sand production was facing by excluding intervals that could produce sand based on geomechanics study made and reduction in PI, but at the end we allow the sand production to increase oil production. Now being conducted an integrated management of sand production by implementing open intervals with high penetration and high density, patterns balance, water injection definition by layer through selective string installed in injector wells, optimization of fluid levels based on pressure drop, real-time sand monitoring, implementation of PCP as artificial lift system, sand fill removal optimization by coiled tubing (using clean fluid and nitrogen), displacement of flow lines and adequacy of surface facilities to better manage produced sand.

It is necessary to learn and live with sand production to increase oil production and profitability in unconsolidated conventional wells instead of looking to avoid it, the solution is to handle in an efficient and economical way.
Intelligent Completions and Horizontal Wells Increase Production and Reduce Free-Gas and Water in Mature Fields
Authors: Rodriguez J. C. , Figueroa A. R.
Published: December 2010

The maturity of the giant fields has resulted in a large number of complex operational and reservoir management problems. The reservoirs pressure has substantially dropped as a natural outcome of the accelerate production rhythm sustained by the field during the productive life. The gas-oil contact and oil-water contact have reached the production intervals in many wells. Horizontal wells have proved to be a valid alternative to drain narrow oil columns in this naturally fractured reservoir. To be able to recover the reserves at sufficiently high rates, new ideas and state of the art technologies need to be implemented to innovate the production process, particularly well completions, to maintain the oil production plateau.

In the mature fields the objective is to maximize production rates to effectively drain the reserves, while minimizing intervention costs. Intelligent wells will be used to increase productivities and recoveries in a less expensive manner, and to significantly reduce the production of free gas and water.

The proposed innovative completion system consists of remotely actuated flow control systems with permanent downhole gauges to permanently monitor the production variables and take actions in real time. This alternative is significantly more effective than the traditional procedure, consisting of selective completions that require expensive subsea interventions to close one zone to open the next one.

In this work, the applicability of multi-purpose intelligent completions for highly productive oil reservoirs has been evaluated from both, the productivity and the operational standpoints. Mandrels will be fitted with intelligent gas lift valves that can be operated from the surface, using downhole gauges for reservoir and production surveillance. Design criteria will be discussed in detail to verify that every productivity case is fully optimized.
Use of iPodTM Technology in Medical-Surgical Nursing Courses: Effect on Grades
Authors: Johnston Robert , Hepworth Joseph , Goldsmith Melissa , Lacasse Cheryl
Published: December 2010

Advances in computer technology, such as the portable and affordable iPodTM, allow students to view lectures anywhere at any time. iPodsTM are of special interest for nurse educators who strive to meet demands posed by a critical nursing shortage. A mixed-methods pilot study was conducted to assess whether iPodTM could be an effective teaching tool for medical-surgical nursing lectures. In a randomized study with 35 participants, together with eight students having their own iPodsTM, grades of students given pre-recorded class lectures on iPodsTM were compared with grades of those who attended lectures without iPodsTM. Learning styles, amount and use of students devoted to iPodTM lectures were considered as well as grades. Most results were not significant, but there was some evidence that the control groups who attended classroom lectures received better grades than iPodTM users, and individuals who used iPodTM more frequently before the final exam received lower grades. These somewhat surprising results suggest the need for further research in the use of this technology as a resource for nursing education delivery.
Uterine Cavity Assessment Prior to IVF
Authors: Pundir Jyotsna , Toukhy Tarek El
Published: December 2010

Approximately 15% of couples are affected with subfertility, of which up to 20% remain unexplained. Uterine cavity abnormalities can be a contributing cause of subfertility and recurrent implantation failure. Uterine cavity assessment has been suggested as a routine investigation in the evaluation of subfertile women. Traditionally, hysterosalpingography has been the most commonly used technique in the evaluation of infertility. Transvaginal ultrasound scan allows visualization of the endometrial lining and cavity, and has been used as a screening test for the assessment of uterine cavity. Abnormal uterine findings on a baseline scan can be further evaluated with saline hysterosonography, which is highly sensitive and specific in identifying intrauterine abnormalities. Hysteroscopy is considered as the definitive diagnostic tool to evaluate any abnormality suspected on hysterosalpingography, transvaginal ultrasound scan or saline hysterosonography during routine investigation of infertile patients. Minimally invasive hysteroscopes have minimized the pain experienced by patients during the procedure and made it feasible to use hysteroscopy as a routine outpatient examination. Following recurrent IVF failure there is some evidence of benefit from hysteroscopy in increasing the chance of pregnancy in the subsequent IVF cycle, both in those with abnormal and normal hysteroscopic findings. Various possible mechanisms have been proposed for this beneficial effect, but more randomized controlled trials are needed before its routine use in the general subfertile population can be recommended.
Differences in the Organisation of Apprenticeship in Europe: Findings of a Comparative Evaluation Study
Authors: Rauner Felix , Wittig Wolfgang
Published: December 2010

This article presents a comparative analysis of governance structures in the dual vocational education and training (VET) systems of Austria, Denmark, Germany and Switzerland. First a theoretical framework for the classification of plural systems such as dual apprenticeship training is discussed. It is argued that governance in VET can be described according to the coherence of the system on the one hand and the rationale of agency on the other. Moreover, it is assumed that four ideal types of governance can be distinguished. A methodology is presented to implement this framework in data collection and analysis and as an evaluation tool for expert workshops. The study recommends a consistent legal framework regarding the cooperation of learning venues and the establishment of an evaluation and feedback scheme in the shape of an assessment during the training process. In order to efficiently coordinate VET practice, VET policy and VET research, the establishment of a ‘VET innovation system’ is suggested.
Chaos or Coherence? Further Education and Training College Governance in Post-Apartheid South Africa
Authors: Wedekind Volker
Published: December 2010

This article frames the lived experiences of management and educators in further education and training (FET) colleges in South Africa, against the backdrop of the radical transformation in the governance of this sector over the past twenty years. The reforms are first described and analysed in terms of their integration and rationale for agency. Second, issues of disjuncture between the internationalized ideal of decentralisation and the emergent, problematic reality of deconcentration and delegation will be explored. Third, data from interviews with principals, council chairpersons and lecturers detail the lived experience of the reform. Governance reforms are perceived as incoherent and lacking a clearly discernible trajectory, and have resulted in highly stressful experiences of alienation, disillusionment and disempowerment by those at ‘the chalkface’. As South Africa faces another cycle of technical and vocational education and training (TVET) reforms, this article suggests that policy makers must take into account the capacities of the people in the system to implement the proposed changes.
Caught in the ‘Triple Lock’? An Evaluation of Governance Structures in the Development of 14–19 Diplomas in England
Authors: Ertl Hubert , Hayward Geoff
Published: December 2010

This article reports on an evaluation of the development of a new type of qualification that is being introduced in England between 2008 and 2011. These diplomas are aimed at 14–19-year-olds, and are expected to present young people with an alternative to established academic qualifications, and also an alternative to established vocational qualifications. The article sets out and discusses the methods used to evaluate the development process of these diplomas. On this basis, it identifies two issues in the development process that raise questions regarding governance structures in education and training in England. The first issue concerns the way in which a multitude of actors and stakeholders have collaborated in the development process of these diplomas. The second issue focuses on the way in which employers have been brought into the development of a qualification that aims at preparing young people better for employment. For both of these issues, the article concludes that new governance structures have been set up that are only partly successful in reaching the goals set by the government. The weaknesses identified are then discussed within the wider contexts of the English qualification system and the relevant regulatory framework in education and training.
Residual Income Compensation Plans and Deferred Taxes
Authors: Johnson Nicole Bastian
Published: December 2010

ABSTRACT: Residual income is a popular performance metric that is often calculated from financial accounting numbers. Practitioners argue that financial accounting earnings and book value suffer from various biases and should be adjusted prior to the residual income calculation so that the resulting residual income metric will have better incentive properties, but they often disagree about what the adjustments should be.

Using the criterion that a residual income performance metric should align owner and managerial investment incentives, I develop a simple investment model to show how financial accounting choices and adjustments must be chosen jointly to achieve incentive alignment. In particular, I examine conflicting recommendations from the practitioner literature about the proper adjustment for deferred taxes and show that more than one adjustment method can achieve incentive alignment if paired with the correct depreciation schedule. Further, I show that relationships among accounting variables introduce constraints that make some policies or adjustments more difficult to work with. The paper concludes with a brief discussion about how the use of sub-optimal adjustments can negatively influence the manager’s investment incentives.
Optimality of Intertemporal Aggregation in Dynamic Agency
Authors: Lukas Christian
Published: December 2010

ABSTRACT: Employee performance evaluations usually take place on an annual basis but quarterly, monthly, or weekly evaluations are by no means exceptional. If their outcomes determine variable pay, finding the optimal frequency of performance evaluations is far from a trivial task. This paper investigates the benefit of intertemporal aggregation of performance measures in a two-period agency with a non-stationary production technology and shows that infrequent evaluation can be efficient even if there is complementarity between tasks in different periods. When the principal cannot fully commit to a two-period contract, the benefit of aggregation is yet larger.
LEN CONgruity
Authors: Hemmer Thomas
Published: December 2010

ABSTRACT: In this paper, I provide some context for judging the relevance and (re)liability of the now seemingly standard LEN-based “insights” into what constitutes more or less “congruent” performance measurement systems. While not particularly complementary, the illustrations aren’t substitutes. To the capable and open-minded reader, however, the paper offers precise statements about the limits of what can be said, generally, about congruity—even when “general” is conditioned on using the LEN model.
The Effects of Profit-Sharing Contract and Feedback on the Sustainability of Cooperation
Authors: Kelly Khim , Tan Patricia Mui-Siang
Published: December 2010

ABSTRACT: This study experimentally examines how the size of a profit-sharing contract offered to a pair of employees and a feedback system that provides information on individual employee cooperativeness affect the sustainability of cooperation. Both the larger profit-sharing contract and the feedback system do not provide explicit economic incentives for cooperation. We find that when there is no feedback system, a larger profit-sharing contract increases the sustainability of cooperation as well as employees’ self-reported reciprocity to the experimental firm and trust in fellow employee. Introducing the feedback system improves the sustainability of cooperation and employees’ self-reported trust in fellow employee. However, the feedback system reduces the positive impact of a larger profit-sharing contract on cooperation sustainability. Our results suggest that firms can rely on increased profit-sharing and feedback, rather than explicit economic incentives for cooperation, to motivate sustained cooperation and improve interpersonal trust.
The Role of Performance Measure Noise in Mediating the Relation between Task Complexity and Outsourcing
Authors: Bai Ge , Coronado Freddy , Krishnan Ranjani
Published: December 2010

ABSTRACT: This paper examines the effect of task complexity on a firm’s decision to outsource and the mediating role of performance measure noise. Using insights from agency and transaction cost economics theories, we predict that task complexity reduces the extent of outsourcing of the task. We further predict that one reason for the negative relation between task complexity and outsourcing is that task complexity increases the noise in performance measures. Noisy performance measures introduce problems in incentive contracting with external vendors and, hence, decrease the extent of outsourcing. Data from 305 inpatient and 1,255 ancillary and outpatient departments of for-profit hospitals provide support for our prediction that performance measure noise mediates the relation between task complexity and outsourcing.
Performance of a commercially available in-clinic ELISA for the detection of antibodies against Anaplasma phagocytophilum, Ehrlichia canis, and Borrelia burgdorferi and Dirofilaria immitis antigen in dogs
Authors: Chandrashekar Ramaswamy , Mainville Celine A. , Beall Melissa J. , O'Connor Thomas , Eberts Matthew D. , Alleman A. Rick , Gaunt Stephen D. , Breitschwerdt Edward B.
Published: December 2010

Objective—To evaluate the sensitivity and specificity of a commercially available in-clinic ELISA for detection of heartworm infection and tick-borne diseases in dogs.

Sample Population—846 serum, plasma, or blood samples obtained from dogs.

Procedures—Samples were evaluated via the in-clinic ELISA to detect antibodies against Anaplasma phagocytophilum, Ehrlichia canis, and Borrelia burgdorferi and Dirofilaria immitis (heartworm) antigen. True infection or immunologic status of samples was assessed by use of results of necropsy, an antigen assay for D immitis, and immunofluorescence assay or western blot analysis for antibodies against B burgdorferi, E canis, and A phagocytophilum.

Results—Sensitivity and specificity of the in-clinic ELISA for detection of heartworm antigen (99.2% and 100%, respectively), antibodies against B burgdorferi (98.8% and 100%, respectively), and antibodies against E canis (96.2% and 100%, respectively) were similar to results for a similar commercial ELISA. In samples obtained from dogs in the northeast and upper Midwest of the United States, sensitivity and specificity of the in-clinic ELISA for antibodies against Anaplasma spp were 99.1% and 100%, respectively, compared with results for an immunofluorescence assay. Samples from 2 dogs experimentally infected with the NY18 strain of A phagocytophilum were tested by use of the in-clinic ELISA, and antibodies against A phagocytophilum were detected by 8 days after inoculation. Antibodies against Anaplasma platys in experimentally infected dogs cross-reacted with the A phagocytophilum analyte. Coinfections were identified in several of the canine serum samples.

Conclusions and Clinical Relevance—The commercially available in-clinic ELISA could be used by veterinarians to screen dogs for heartworm infection and for exposure to tick-borne pathogens.
Estimation of the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus in sentinel cattle of dairy herds located at high and low elevations in southern Mexico
Authors: Adell Aiko D. , Perez Andres M. , Navarro Lopez Roberto , Lopez Gonzalez Irene , Paz Ramirez Pedro , Rodriguez Luis L.
Published: December 2010

Objective—To estimate the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus (VSNJV) in sentinel cattle of dairy herds located at high and low elevations in southern Mexico and to determine the factors associated with an increase in VSNJV transmission.

Animals—471 dairy cattle in 4 free-ranging dairy herds located at high and low elevations in southern Mexico.

Procedures—Serum samples from all cattle were screened by use of serum neutralization (SN) tests for antibodies against VSNJV. Cattle with SN titers < 1:20 were designated as sentinel cattle and tested every 10 weeks for seroconversion to VSNJV (SN titer ≥ 1:80). A Cox proportional hazards regression model was used to compare the hazard for seroconversion between sentinel cattle located at high and low elevations and kept under similar management and nutritional conditions.

Results—Hazard of VSNJV seroconversion was significantly higher for sentinel cattle located at high elevations, compared with the hazard for sentinel cattle located at low elevations. Dairy cattle located at high elevations seroconverted to VSNJV more frequently during the rainy season and the beginning of the dry season.

Conclusions and Clinical Relevance—Seroconversion to VSNJV was more likely in dairy cattle in southern Mexico located at high elevations than in dairy cattle located at low elevations. These findings should contribute to understanding the dynamics of VSNJV infection in endemic areas and should be useful in the design of effective preventive and control strategies to decrease the impact of future VSV incursions.
Effects of intracameral administration of α-chymotrypsin on intracapsular lens extraction and postoperative outcome in clinically normal dogs
Authors: Maggs David J. , Nasisse Mark P. , Marrion Ruth M. , Priddy Nelson H. , Dodam John R.
Published: December 2010

Objective—To assess the intraoperative and postoperative clinical effects and histologic effects of intracameral administration of α-chymotrypsin in clinically normal dogs undergoing standard intracapsular lens extraction (ICLE).

Animals—6 young adult male dogs without evidence of systemic or ocular disease.

Procedures—All dogs underwent bilateral ICLE 7 minutes following injection of 75 U of α-chymotrypsin or an identical volume (0.5 mL) of a commercially available balanced saline solution (BSS) into the posterior chamber of the eye. Ease of lens extraction was subjectively assessed and intraoperative intraocular hemorrhage and fibrin accumulation scored. For 27 days after surgery, ocular hyperemia and discharge, chemosis, corneal edema, hyphema, and aqueous flare were scored, and intraocular pressure (IOP) was measured. Thirty days after surgery, histologic evidence of anterior synechia, collapse of and inflammation within the iridocorneal angle, and iritis were scored.

Results—In 5 of 6 dogs, the surgeon was able to correctly identify the eye treated with α-chymotrypsin on the basis of ease of lens extraction. Mean intraoperative intraocular hemorrhage and fibrin scores for BSS-treated eyes were significantly higher than for α-chymotrypsin-treated eyes. Postoperatively, there were no significant differences between treatments for any clinical variables, including IOP Histologic scores were not significantly different between treatments for any variable. Vision was lost as a result of glaucoma in 1 α-chymotrypsin-treated eye and 1 BSS-treated eye.

Conclusions and Clinical Relevance—Intracameral administration of 75 U of α-chymotrypsin 7 minutes before ICLE facilitated lensectomy without apparent adverse effects in clinically normal dogs.
Pharmacokinetics, protein binding, and tissue distribution of orally administered cefpodoxime proxetil and cephalexin in dogs
Authors: Papich Mark G. , Davis Jennifer L. , Floerchinger Amanda M.
Published: December 2010

Objective—To determine the effect of protein binding on the pharmacokinetics and distribution from plasma to interstitial fluid (ISF) of cephalexin and cefpodoxime proxetil in dogs.

Animals—6 healthy dogs.

Procedures—In a crossover study design, 25 mg of cephalexin/kg or 9.6 mg of cefpodoxime/kg was administered orally. Blood samples were collected before (time 0) and 0.33, 0.66, 1, 2, 3, 4, 6, 8, 10, 12, 16, and 24 hours after treatment. An ultrafiltration device was used in vivo to collect ISF at 0, 2, 4, 6, 8, 10, 12, 16, and 24 hours. Plasma and ISF concentrations were analyzed with high-pressure liquid chromatography. Plasma protein binding was measured by use of a microcentrifugation technique.

Results—Mean plasma protein binding for cefpodoxime and cephalexin was 82.6% and 20.8%, respectively. Mean ± SD values for cephalexin in plasma were determined for peak plasma concentration (Cmax, 31.5 ± 11.5 μg/mL), area under the time-concentration curve (AUC, 155.6 ± 29.5 μg•h/mL), and terminal half-life (T½, 4.7 ± 1.2 hours); corresponding values in ISF were 16.3 ± 5.8 μg/mL, 878 ± 21.0 μg•h/mL, and 3.2 ± 0.6 hours, respectively. Mean ± SD values for cefpodoxime in plasma were 33.0 ± 6.9 μg/mL (Cmax), 282.8 ± 44.0 μg•h/mL (AUC), and 5.7 ± 0.9 hours (T1/2); corresponding values in ISF were 4.3 ± 2.0 μg/mL, 575 ± 174 μg•h/mL, and 10.4 ± 3.3 hours, respectively.

Conclusions and Clinical Relevance—Tissue concentration of protein-unbound cefpodoxime was similar to that of the protein-unbound plasma concentration. Cefpodoxime remained in tissues longer than did cephalexin.
Measurement of ascorbic acid concentration and glutathione peroxidase activity in biological samples collected from horses with recurrent airway obstruction
Authors: Tan Rachel H. H. , Thatcher Craig D. , Buechner-Maxwell Virginia , Christmann Undine , Crisman Mark V. , Werre Stephen R.
Published: December 2010

Objective—To measure the ascorbic acid (AA) concentration in bronchoalveolar lavage fluid (BALF) and cellular glutathione peroxidase (cGPx) activity in RBCs and WBCs from peripherally obtained blood and in cells from BALF to determine whether differences existed between the 2 major redox systems in recurrent airway obstruction (RAO)-affected and -nonaffected (control) horses and between systemic and local pulmonary responses in the glutathione redox system.

Animals—16 adult horses in pairs: 8 healthy (control) and 8 RAO-affected horses.

Procedures—Physical examination data and biological samples were collected from horses before (remission), during, and after (recovery) environmental challenge with dusty straw and hay. At each stage, BALF cell AA concentration and RBC, WBC, and BALF cell cGPx activity were measured.

Results—Compared with control horses, RAO-affected horses had significantly higher cGPx activity in RBCs at all points and in WBCs during remission and challenge. The BALF cell cGPx activity was higher in RAO-affected horses during recovery than during remission The BALF cell AA concentration did not differ significantly in control horses at any point, but total and free AA concentrations were significantly lower in RAO-affected horses during the challenge period than during remission and recovery periods.

Conclusions and Clinical Relevance—High cGPx activity suggested this redox system was upregulated during exposure to dusty straw and hay to combat oxidative stress, as AA was depleted in RAO-affected horses. The relative delay and lack of comparative increase in cGPx activity within the local environment (represented by BALF cells), compared with that in RBCs and WBCs, might contribute to disease in RAO-affected horses.
In vitro evaluation of free-form biodegradable bone plates for fixation of distal femoral physeal fractures in dogs
Authors: Marcellin-Little Denis J. , Sutherland Brian J. , Harrysson Ola L. A. , Lee Erica S.
Published: December 2010

Objective—To design and manufacture free-form biodegradable polycaprolactone (PCL) bone plates and to compare mechanical properties of femoral constructs with a distal physeal fracture repaired by use of 5 stabilization methods.

Sample Population—40 canine femoral replicas created by use of additive manufacturing and rapid tooling.

Procedures—Surgery duration, mediolateral and craniocaudal bending stiffness, and torsional stiffness of femoral physeal fracture repair constructs made by use of 5 stabilization methods were assessed. The implants included 2 Kirschner wires inserted medially and 2 inserted laterally (4KW), a commercial stainless steel plate (CSP), a custom free-form titanium plate (CTP), thin (2-mm-thick) biodegradable PCL plates (TNP) placed medially and laterally, and thick (4-mm-thick) PCL plates (TKP) placed medially and laterally.

Results—Surgical placement of 4KW was more rapid than placement of other implants The mean caudal cantilever bending stiffness of CTP and CSP constructs was greater than that for TNP TKP and 4KW constructs, and the mean caudal cantilever bending stiffness of TNP and TKP constructs was greater than that for 4KW constructs. The mean lateral cantilever bending stiffness of TKP constructs was greater than that for 4KW constructs. Differences among construct types were not significant in yield strength, ultimate strength, yield torque, and ultimate torque.

Conclusions and Clinical Relevance—The mechanical properties of fracture repair constructs made from free-form PCL biodegradable plates compared favorably with those of constructs made from Kirschner wires. The impact of PCL plates on musculoskeletal soft tissues, bone healing, and bone growth should be evaluated before clinical use.