bluuebunny/crossref_metadata_2025 huggingface dataset:
Detailed Facies Definition and 3D Static Model: Reservoir Management of the Eocene Producing Units in Block X of the Talara Basin in Northwest Peru
Authors: Laverde Fabio , Pozo Gerardo , Miranda Flavio , Carrillo Gonzalo , Torres Kevin , Sanchez William , Alvarez José Luis , Contreras Fabio
Published: December 2010

Block X, located in the Talara Basin in northwest Peru, is one of the oldest producing basins in America. The reservoirs that have been studied are the Eocene Mogollon, Ostrea, Echinocyamus, and Helico units. The present structural model has benefited from previous jobs performed by Petrobras, where an old extensive fault system oriented northeast to southwest was affected by a later fault system trending northwest to southeast. Low-angle faults have cut the upper section of the Helico unit, consequently moving older sequences to the northwest. This structural setting controls the distribution of facies bodies, their interaction, size, and geometry, and the quantity of sand facies.

Based on an integrated facies analysis from numerous outcrops, 21 cored wells and more than 750 well-log motifs, a reliable stratigraphic framework was constructed that resulted in the identification of specific facies associations, stratigraphic or depositional surfaces, defining genetic units. Gross depositional fluvio-deltaic environments of the Mogollon succession were interpreted toward the southeast, shoreface at the Ostrea facies throughout the area, the deltaic and fluvial for the Echinocyamus in localized areas, and the tidal flat-beach-coastal plain toward the northeast, with the important development of fan deltas into submarine canyon-fills. This development was recorded within the Helico at the southwest of the study area. Because of the many years of production data available, the geologic model and facies distribution could be adjusted with dynamic data, such as pressure data, production tests and water cut. A possible way of achieving such conditions included adjusting the connectivity between sand bodies, their orientation and the vertical communication.

The products of the integrated study included: 1) mapped areas and zones of potential reservoir connectivity, and 2) geological model building used in 3D geostatic modeling. Mapping of the sequences resulted in the proposal of new infill wells and potential workovers. The results of the 3D static model work were: a) realistic fine-scale geological models that were consistent with the observed data, b) calculations of uncertainties in the oil-in-place volume.
Managing Downhole Vibrations for Hole-Enlargement-While-Drilling in Deepwater Environment: A Proven Approach Utilizing Drillstring Dynamics Model
Authors: Compton Molly , Verano Fernando , Nelson Gail , Wu Sean Xianping , Bits Smith
Published: December 2010

Deepwater drilling often requires simultaneous hole-enlargement-while-drilling to improve project economics and efficiently deliver wellbore requirements. The challenge is to properly adjust reamer aggressiveness to match PDC bit dynamics to reduce damaging vibrations while maximizing overall drilling efficiency.

Recent R&D efforts, focused on redesigning the BHA and optimizing drilling parameters, have successfully reduced bit/under- reamer vibrations. In addition, many operators and service providers have established rig-site procedures to recognize and mitigate vibrations. However, the results are still mixed and the lack of understanding the root causes of different vibrations is considered to be the major hurdle to improving drilling efficiency and performance.

To solve this challenge an advanced dynamics model was developed which incorporates the following critical information: Mechanical rock properties (UCS)

Bit/reamer design including cutter, body, gauge profile Physical characteristics of BHA components Formation characteristics (heterogeneous, anisotropy, interbedded) Well trajectory and borehole geometry Drilling parameters (WOB/RPM)

This model can be applied to any drillstring configuration to provide BHA detailed information about RSS, PDM, PDC/roller cone, stabilizers, reamers, MWD/LWD and other downhole tools. This FEA model accurately predicts the drilling system's dynamics behavior from bit to surface and simulates the transient response of the entire system in time domain. Using this model, the combined effects of bit, reamer, BHA and drilling parameters have on vibration can be quantified and optimized before commencing field operations. This innovative technology provides an effective tool to optimize drilling performance without using the costly trial-and-error approach.

An operator working in the Gulf of Mexico (GoM) required hole-enlargement-while-drilling to open a 12-1/4" pilot hole to 14- 3/4" from 13,000ft MD to approximately 20,000ft MD. The advanced drillstring dynamics model was utilized to optimize the BHA, bit and drilling parameters to minimize potential stick-slip and lateral vibrations. The optimization study, along with the operator's improved drilling practices, resulted in a 24% increase in penetration rate (ROP) compared to an offset well. Excluding the directional portions of the wellbore, the increase in ROP was calculated at 43%. The penetration rate increase reduced rig-time usage by 13.4hrs for a savings of $558,000USD.
Multidisciplinary Workflows Applied in Reservoir Characterization: A Heavy Oil Field Case Study During Early Stages of the Asset Life-Cycle
Authors: Astudillo D. , Porlles J.
Published: December 2010

New oil fields have been recently discovered in remote areas of the Peruvian Amazonian rainforest. Heavy oil was tested in Cretaceous age reservoirs of Marañon basin: Casablanca, Vivian and Chonta. Conceptual development options for these fields are being analyzed; that is why, a proper characterization of rock-fluid properties of reservoirs is particularly important in this early stage of the asset life-cycle to optimize the field development strategy.

Several methodologies of reservoir characterization have been widely discussed in the literature; however not always interdisciplinary workflows are applied in data acquisition and processing for reservoir characterization. Study cases and lessons learned from studies carried out in a recently discovered heavy oil reservoir are discussed, as well as, the workflow applied to get representative SCAL data and integrated well test interpretation is described.

On the one hand, the process to achieve representative SCAL data includes sample selection criteria, SCAL program, and data validation to come up with a high quality data set to refine reservoir models. Sample selection technique used for this study is based on Global Hydraulic Elements (Corbett et al. 2004)5, which is combined with sedimentological studies, electrofacies logs and statistics from geo-cellular 3D model. This is aimed to select representative core plug samples for a cost effective lab program execution. On the other hand, routine core analysis data was integrated into well test interpretation to understand flow units and select near wellbore flow models that are consistent with petrophysical data. Finally, after processing and validating information, a selected set of data was incorporated into reservoir models.

The workflows discussed in this paper look forward to developing synergies in multy-disciplinary teams working on reservoir characterization, which could allow to improve the making decision process during early stage of the field.
Numerical Transient Testing Deconvolution as a Reservoir Modeling Tool for Gas Fields in Early Development Phase
Authors: Quispe J. , Huerta V. A. , Quispe D.
Published: December 2010

Recently, new gas condensate fields have been discovered in remote areas of the Amazonian rainforest, Peru. Some of these fields tested gas and condensate from Nia, Noi and Ene reservoirs; Accuracy in well testing interpretation will play a crucial role in identifying geological features and solving uncertainties while characterizing these fields.

Conventional interpretation methods are not completely rigorous while trying to match pressure transient behavior by semi-log pseudo-pressure and derivative plots; usually, condensate banking phenomena and complex geological features are not precisely described with inferred models, especially in relatively new fields with little information.

An integrated approach composed by the combination of numerical simulation plus deconvolution technique offers comparative advantages compared to conventional transient testing analysis when discriminating between potential interpretation models and a sound reservoir characterization; contribution of geology and geophysics is very critical to identify structural features such as faults, flow barriers and fluid-contact positions, as well as, to predict pressure support intensity and predominant drive mechanism.

This paper provides general guidelines to integrate reservoir modeling disciplines to numerical deconvolution analysis so as to precise well testing interpretation of fields in early development phases; some applications, such as a sound methodology to calculate a representative drainage radius for the whole drawdown time, and its contribution to mitigate uncertainty in resources estimation, as well as, a more detailed characterization of late-time effects (facies-changes and fluid-contacts) in Peruvian gas condensate fields were emphasized.
Indexing and Normalizing Natural Gas Endowment
Authors: Aguilera R. F. , Aguilera R.
Published: December 2010

A novel method is presented for indexing and normalizing natural gas endowment. The approach is demonstrated with data from Latin America and Caribbean (LAC) countries. Endowment, as defined by the USGS, refers to the sum of known volumes of hydrocarbons (cumulative production plus remaining reserves) and undiscovered volumes.

The method uses a variable shape distribution model (VSD) to fit the conventional natural gas endowment published by the USGS (2000) for 29 petroleum provinces in LAC countries. The fits are good with coefficients of determination (R2) greater than 98% in all cases. The data are indexed and normalized to generate tables and crossplots of number of petroleum provinces versus normalized endowments for LAC countries.

The LAC curves are compared with normalized endowments from other petroleum provinces in regions around the world, including North America, Europe, Asia Pacific, the Middle East, NorthAfrica, and the former Soviet Union. The results give the method predictive power for estimating conventional natural gas endowment in LAC petroleum provinces that at present have very small to negligible exploration activity.

Of particular importance, from a practical point of view, is the fact that all the real data and VSD curves for the petroleum provinces of the various regions considered in this study display generally a concave pattern throughout, except for the curve of Latin America and the Caribbean, which displays a distinct convex pattern at the largest values of gas endowment. The complete LAC curve displays the shape of an inverted "S". The comparison suggests that there is potentially a gigantic volume of gas in the region that has not been considered in previous studies.
Producing the Intelligent Riser: Advances in Fiber-Optic Monitoring and Visualization Applications Within Flexible Risers
Authors: Andersen B. , Staveley C. , Worsley J. , Watley D. , Naldrett G. , Bennett P. J.
Published: December 2010

Unbonded flexible risers are a critical part of offshore field architecture bringing oil and gas from seabed to platforms on the surface. A failure in operation will result in stop of production and hence a significant loss of revenue. Risers are subject to a number of loading issues including internal and external pressure, vessel motions and current and wave actions. As a result, risers, endure significant strain levels which can impact on their integrity and functionality.

The recent implementation of fiber optic monitoring embedded in flexible risers, is an important step towards turning risers into inspectable structures. The embedded monitoring systems ensure the asset can operate safely at its optimum level for the maximum period of time. The combined use of optical point sensors and fully distributed sensors allow various events to be monitored. This includes breach of outer sheath, condensate build up, polymer temperature, pipe temperature during shut in, fatigue and wire break.

The traditional industry method for combating these issues has been extensive onshore testing on small sections of the riser allowing the operator to build up a bank of fatigue and reliability data which is used to statistically forecast the strains and stresses the riser will encounter. This data takes into account expected changes throughout the lifecycle of the riser, such as material degradation and environmental issues including storms and hurricanes. The main inspection method in operation to back this up has been expensive inspection campaigns by diver or ROV focusing on external damage.

New advances in optical technology and riser manufacturing techniques mean that a suite of real-time monitoring can provide a far more accurate picture of a riser's condition during operation. This improves decision making by allowing structural and temperature issues to be detected at the earliest possible stage and rectified in the most efficient manner, ensuring risers satisfy safety and regulatory requirements and help maximize oilfield productivity. The enabled condition dependent maintenance of risers will reduce the need for expensive ROV operations for inspection.

Real time riser monitoring is set to play an increasingly important role as the operators start to insist on the adoption of this technology in the risers delivered to them. As oil production reaches into deeper and deeper water depths, the real time understanding of the integrity of the risers will become paramount.

This paper details the advances that have been made in optical monitoring and visualization techniques and their application within the intelligent riser.
Maximum Horizontal Stress and Wellbore Stability While Drilling: Modeling and Case Study
Authors: Li S. , Purdy C.
Published: December 2010

Maximum horizontal stress is a critical parameter used in drilling optimization and wellbore stability modeling. Current maximum horizontal stress prediction from wellbore breakout was based on the maximum tangential stress on the wellbore wall to be equal to the rock uniaxial compressive strength. We assume that the vertical, minimum and maximum horizontal stresses define a specific relationship when the stresses in the formation are in equilibrium. Based on a generalized Hooke's law with coupling the equilibrium of stresses and pore pressure, the maximum horizontal stress can be solved using this relationship. This new technique can reduce the uncertainty of in-situ stress prediction by narrowing the area of the conventional polygon of the in-situ stresses. We also propose a new method of the maximum horizontal stress determination from analyses of drilling-induced near-wellbore stresses and breakouts. The near-wellbore stresses are obtained from poroelastic equations. By using Mohr-Coulomb failure criterion, the maximum horizontal stress magnitude can be derived from these equations and from analysis of wellbore breakout obtained from borehole caliper logs. The new technique is compared to the existing methods in an example from measured borehole failures in a case study. These comparisons demonstrate that new technique provides a much better result than the current available methods, because the wellbore failure is related with all of the near-wellbore stresses.

A case study has been conducted in a GOM oil field to predict pre-drill wellbore stability, where borehole instability was the main cause of borehole trouble time in offset wells. Using the proposed in-situ stress method, an improved borehole stability model was built to predict the pre-drill mud weight window. Applying this prediction, wellbore failures and drilling risks were greatly reduced.
Talara Basin, Peru: Structural and Stratigraphic Characterization Based on 3D-Seismic Data
Authors: Diniz S. H. , De Sá F. R. , Rodriguez C. , Santos C. G. , Cruz J. M. , Beas W. E.
Published: December 2010

Along the past decades the prolific Talara Basin, located at the northwest part of the Peruvian coast, has been intensively studied based mainly on the huge amount of onshore wells on the area. Beside this, contributions come up from 3D seismic. These contributions are stratigraphic and/or structural analysis, which provide suggestions about reservoir communication, fault movement and optimize well positioning.

The reservoir characterization methodology applied on this work used 3D PSDM seismic data. The first step aimed to better understand deep reservoir levels (Lower Eocene and Paleozoic), that are less sampled by wells than upper levels (e.g., Middle Eocene). The second step focused on Middle Eocene reservoirs, sampled by tens of wells with a good geological correlation. From well data and geological interpretation, it is well known that Lower Eocene reservoirs are high energy fluvial systems – this depositional pattern appeared with a distinct seismofacies in the entire seismic cube. Seismic data and well logs showed that Lower Eocene presents more fractures and faults than Middle Eocene. However, the relation between directions and fracture classification as open, semi-open or closed fractures was not conclusive.

The seismic facies found at Middle Eocene show sin-depositional differential tectonics movements that could have caused compartmentalization. At this level, seismic facies are very clear, with strong and parallel reflectors, indicating the presence of amalgamated lobes (probably derived from erosion of an eastern ridge located). Identified seismic anomalies were mainly related to structural highs, associated to hydrocarbon saturated reservoirs.

An understanding of stress field behavior along geological time is very important to achieve a better trapping model and hydrocarbon migration routes. In this work, the high number of structures observed provided the tools to set up an event chronology. According to the stress history, N70W normal faults acted as migration routes probably during Miocene. Considering the last compressive reactivations (occurred between Upper Eocene and Oligocene) these previously migration routes could be changed to sealing faults.
Gas Production From Hydrates Dissociation in Marine Sediments
Authors: Llamedo M. A. , Provero D. , Viloria A. , Yánez G. F. E.
Published: December 2010

The quantity of gas accumulated as gas hydrates has been estimated as more than the half of the total fossil energy, and it is considered as the most prominent energy resource to cover the needs of natural gas in the future. Due to the limited data available, important efforts in the harvesting of real data have been carried out and additional simulation studies for this not conventional reservoir like gas hydrates accumulations are considered. The two main mechanisms to define the exploitation strategy are depressurization and thermal stimulation; and reservoir numerical simulation which are considered important tools to get characterization and evaluation of the optimization production process. A three-dimensional commercial numerical simulator is used to model gas production from gas hydrates dissociation, considering the thermodynamic equilibrium and the kinetic intrinsic, both simultaneously. Depending on the defined deposit configuration, gas hydrates accumulations can be associated a biphasic zone with gas free layer below the gas hydrates zone (deposits Class 1), and for this configuration gas production by depressurization is the most favorable one. The initial production from the free gas layer drives the process of dissociation of methane hydrates zone. In the case where the configuration includes the presence of an aquifer or mainly water in a biphasic zone below to the gas hydrates zone (deposits Class 2); the more often evaluated mechanism is hot water or steam injection as thermal stimulation behave like an acceptable alternative for gas production, the rise in temperature promotes the dissociation of the upper hydrates reaching temperatures to that of equilibrium condition. Gas production is associated with water production.
New Design of High-Performance Cement Systems for Zonal Isolation: Influence on Porosity, Rheological Parameters and Chemical and Mechanical Resistance
Authors: Miranda C. R. , Toledo Filho R. D. , Fairbairn E. M. , Thaumaturgo C. , Vargas A. A. , Oliveira G. M. , Teixeira K. C.
Published: December 2010

High-Performance Cement Systems consist of cement slurry designs based on engineered particle size distributions that aim to achieve improved mechanical properties and higher chemical resistance compared to traditional cement slurry compositions.

The methodology used to obtain High Performance Cement Systems for Oilwells is based on the Compressive Packing Model, where higher content of solids is achieved by using materials having specific particle size distributions. With these higher solids content slurries, a lower proportion of water is required, and thus improved mechanical properties and better chemical resistance can be obtained.

The High-Performance Cement Systems, also called High-Packing Cement Systems, in the present work were designed using the Compressive Packing Model, which was developed to design high performance concretes. Various systems for oilwells were designed in this work using Class G Portland Cement, Silica Fume and Hollow Microspheres.

The high-performance cement system properties, such as rheological parameters, compressive strength, porosity and acid resistance are shown and compared to traditional cement systems properties.
Economic Evaluation of Steam and Nitrogen Injection on SAGD Process
Authors: Rios V. S. , Laboissière P. , Trevisan O. V.
Published: December 2010

Thermal recovery methods made possible the production of heavy oil fields considered non-commercial with conventional methods of recovery. In this context, steam injection has proved to be a major cost-effective alternative for increasing the heavy oil recovery. Steam Assisted Gravity Drainage (SAGD) is one of the field proven improvements. It uses two horizontal wells with the steam injector above the producer, which stays at the base of the reservoir. Sweeping the reservoir with the growth of a steam chamber.

The variations on conventional SAGD involving non-condensable gases show a new trend. Numerical results suggest that after a certain period of time operating only with steam is effective to inject only inert gas. In this process the steam chamber keeps growing even after the steamflood is stopped. The purpose of the gas injection is to maintain the reservoir pressure elevated to keep the oil production. The cumulative steam oil ratio has a downward trend, yielding a reduction in the project costs. In this paper, a numerical study of the SAGD method in field scale is conducted. The reservoir model is simulated with properties obtained from a Brazilian onshore field. The methodology used involves an investigation of the main parameters that influence the application of the method and, according to a sensitivity analysis. The aim is to determine the best time to start gas injection looking to maximize NPV.

A commercial software is used to simulate the injection of nitrogen after steamflooding the reservoir in order to obtain the results that are used to perform the sensitivity analysis. It was verified that the steam injection rate and the bottom hole pressure are decisive parameters to be considered. The simulations show that the nitrogen injection after a determined period of time of continuous steam injection reflects in a reduction in the order of 40% of the steam oil ratio. However, the cumulative oil production is almost the same when compared with the conventional SAGD.
First Retrievable Directional Casing While Drilling (DCwD) Application in Peruvian Fields Generates Time Reduction and Improves Drilling Performance Preventing Potential Non-Planned Downtime
Authors: Beaumont E. , de Crevoisier L. , Baquero F. , Sanguino J. , Herrera D. , Cordero E.
Published: December 2010

Drilling Operations in Peruvian Jungle requires a complex logistical preparation similar to an offshore project. This high logistic cost that is necessary to drill in this area means a big investment and strongly impacts the daily drilling cost. To minimize potential non productive time (NPT), potential problems that were identified in offset wells (borehole instability, gumbo shales, stuck pipe, etc.), and to improve the drilling performance, Perenco Peru Limited decided to use Directional Casing while Drilling (DCwD) technology in their Block 67 campaign wells. Two wells (Piraña-4D and Dorado-2D) were drilled with this technology obtaining success and achieving the operator's targets.

The objectives for the Casing Drilling operations on the Block 67 wells were:

Prove feasibility of both vertical and directional casing drilling technologies Save time upon the whole section by simultaneously Drilling and casing-off problematic formations Demonstrate efficiency of the technology to reduce risks associated with conventional drilling that could easily result in losing the well and further unplanned sidetracks Prove adaptability of the technology to different well conditions (mainly variance on well trajectory) Evaluate the economical viability of the technique (cost & time savings)

This paper describes these experiences in terms of planning, preparation, execution and evaluation of results including the lessons learnt generated during the process.
Traditional Material-Balance Analysis from a Stochastic Point of View: Predicting Reservoir Performance
Authors: Galecio R. A. , Huerta V. A.
Published: December 2010

We see traditional material balance calculations as an old technique when we face the challenging issue of forecasting reservoir performance, numerical simulation is by far the selected method used by reservoir engineers; but, what happen in an early development phase of an oilfield, when we have scarcely data and a high degree of uncertainty associated?. The aim of this work is to show that methods based on MBE can be successfully integrated with Monte Carlo technique in order to predict reservoir performance under these circumstances.

We have selected two methodologies; the first one was proposed by Tarner, designed to predict the Cumulative Oil production as a function of the average reservoir pressure (reservoir depletion). Tarner uses simultaneously the MBE and the GOR definition to estimate the value of the Cumulative Gas Production, through the convergence of both values. The second method was proposed by Tracy, in which a trial and error procedure is followed to converge to the instantaneous Gas Oil Rate, which in turns, allows us to estimate the incremental cumulative oil production. Special attention was given to the ratio of relative permeability, because both methods are quite sensitive to it, and usually this ratio is calculated by correlations (in absence of special core analysis). Flow rate forecasts were calculated using Vogel approach and regarding decline rates of local oilfields.

A macro in excel was plugged into a commercial risk analysis software in order to combine the material balance approach with Monte Carlo simulation, so as to address simultaneously to reservoir properties uncertainty and limited production records, instead of getting on with complex numerical simulation models. A small mature area in Talara Basin producing from Mogollón formation was successfully tested with this integrated tool; in contrast to the conventional decline curve forecasts, a sound set of analytical predictions weighed by certainty were prepared, which is indeed more reliable for a decision-making process.
Optimization of Inflow Control Device Placement and Mechanical Conformance Decisions Using a New Coupled Well-Intervention Simulator
Authors: Thornton K. , Soliman M. Y. , Jorquera R.
Published: December 2010

To optimize production from long horizontal wells, the completion design engineer must consider reservoir heterogeneity so that water breakthrough can be avoided. Reservoir heterogeneity becomes even more critical when combined with the presence of a strong aquifer, and one of the methods commonly used to control this condition has been to have uniform water movement towards the horizontal well. Traditionally, inflow control devices (ICDs) have been used in horizontal wells to achieve this goal. However, design of the ICDs to achieve optimum productivity from the horizontal well can only be achieved by properly linking the ICD design to reservoir characteristics. Unfortunately, operators and service companies have often applied ICDs without adequate methods to verify completion efficiency over time, since available tools to quantify reservoir complexities and their effects over time have not been readily available.

In this paper, a methodology and a numerical simulation approach that are designed to improve the success ratio of mechanical conformance treatments is presented. This approach combines a comprehensive solution for determining ICD effects on the wellbore behavior with a reservoir numerical simulator. The methodology considers the following:

Placement techniques Annular flow control ICD flow size, rate, and number of ICDs Reservoir fluid properties Reservoir permeability distribution effects Fluid-property changes including prediction of water and gas breakthrough over time.

A numerical simulator that couples the wellbore and reservoir characteristics provides an efficient means for developing a method to optimize ICD design and initialization. Simulated examples are given for basic conformance phenomena such as coning and channeling. Two field cases will be presented that demonstrate the application of this method and how it designed an optimum ICD completion solution.

This method reduced risks associated with ICD design and optimized the system designs through more accurately predicting water and hydrocarbon production.
Should All Patients with Serous and Clear Cell Endometrial Carcinoma Receive Adjuvant Chemotherapy?
Authors: Boren Todd P , Miller David S
Published: December 2010

Uterine papillary serous carcinoma (UPSC) and uterine clear cell carcinoma (UCCC) represent two rare subtypes that have an increased risk of recurrence and worse overall survival compared with the more common endometrioid endometrial cancers. Meaningful data in the form of prospective randomized trials is lacking for both advanced and early-stage UPSC and UCCC. Data extrapolated from prospective trials in advanced endometrioid endometrial cancer and retrospective trials on early-stage UPSC suggest that adjuvant platinum and taxane-based chemotherapy may provide a survival benefit for these patients. Future trials specifically examining UPSC and UCCC are needed to elucidate the optimal treatment regimen for these patients. Given the current data, the option of chemotherapy should be considered in treatment-planning discussions for all patients with UPSC and UCCC.
Heart Rate Response and Chronotropic Incompetence in Exercise Stress Testing of Asymptomatic Women
Authors: Mansur Alfredo Jose , Nunes Rafael Amorim Belo
Published: December 2010

Evaluation of: Gulati M, Shaw LJ, Thisted RA, Black HR, Bairey Merz CN, Arnsdorf MF: Heart rate response to exercise stress testing in asymptomatic women: The St. James Women Take Heart Project. Circulation 122, 130–137 (2010). Peak heart rate achieved with exercise in 5437 asymptomatic women submitted to symptom-limited exercise stress testing demonstrated an inverse relationship with increasing age, expressed by 206-0.88(age), which is lower than the traditional estimate of 220-(age). A nomogram was derived. This new formula for estimating peak heart rate during exercise and the derived chronotropic incompetence was found to be a more accurate predictor of all-cause mortality in this study sample.
Gender Issues in Multiple Sclerosis: An Update
Authors: Jobin Céline , Larochelle Catherine , Parpal Hélène , Coyle Patricia K , Duquette Pierre
Published: December 2010

Although multiple sclerosis (MS) affects both women and men, women are more susceptible to MS than men. Accumulating evidence indicates that the incidence and prevalence of MS is increasing, more so in women than in men. Owing to pregnancy, differing hormonal states and distinct social roles, the impact of MS differs between women and men. Since Patricia K Coyle published a review on gender issues in MS, multiple studies have added to the body of knowledge. This update will summarize the current thinking on gender-related issues in MS and we will address incidence and prevalence, hormonal factors, pregnancy and breastfeeding, genetics, course and prognosis, imaging, treatment and psychosocial aspects. Future progression within this field will help elucidate the cause of and define the treatment of MS.
Treatment Failure and Recurrence of Cervical Intraepithelial Neoplasia in HIV-Infected Women
Authors: Pantanowitz Liron
Published: December 2010

Evaluation of: Reimers LL, Sotardi S, Daniel D et al.: Outcomes after an excisional procedure for cervical intraepithelial neoplasia in HIV-infected women. Gynecol. Oncol. 119, 92–97 (2010). In a retrospective cohort study of 136 HIV-infected women who had a loop electrosurgical excision procedure (LEEP) or cone procedure for cervical intraepithelial neoplasia (CIN), Reimers et al. show that treatment failure and recurrence of CIN was common. Most recurrent CIN lesions, and those detected at treatment failure, were high-grade lesions. Both treatment failure and subsequent recurrence of CIN were found to be high in women with poorly controlled HIV, after LEEP, and those with positive cervical tissue margins following treatment. Based on these data the authors suggest that cervical conization may be superior to LEEP in the treatment of CIN in HIV-infected women.
Governance of Vocational Education and Training in the United States
Authors: Stone James R. , Lewis Morgan V.
Published: December 2010

Local educational agencies (of which there are more than 14,000) have the primary responsibility for governance of public vocational education and training (VET) in the United States. Local agencies operate within a framework of state legislation and regulations that are heavily influenced by federal legislation. The federal government offers funds to the states for the support of VET. To qualify for these funds, states must submit plans to the federal government describing how they will use the funds to achieve the intent of federal law. States, in turn, require local agencies to submit plans for their use of the funds. The diversity of this system is further complicated by the variety of ways that states assign responsibility for the administration of secondary and postsecondary VET. Initiatives to link secondary and postsecondary training include Tech Prep, career pathways, and, in the most recent federal legislation, programs of study. Almost all government-supported skill training outside the education system occurs through the Office of Apprenticeship and the Job Corps, both of which are administered by the federal Department of Labor. The number of trainees in these programs is much lower than that of those receiving skill training from educational institutions.
Performance Measure Aggregation, Career Incentives, and Explicit Incentives
Authors: Autrey Romana L. , Dikolli Shane S. , Newman D. Paul
Published: December 2010

ABSTRACT: We examine a setting in which managers have differential career concerns and firm performance is publicly observed using disaggregated measures that are incrementally informative but costly to contract upon. In such a setting, when do firms contract on aggregated rather than disaggregated performance measures? We show that at intermediate levels of managerial career concerns contracting on an aggregate measure can be welfare-enhancing. In this case, the net cost of both contracting directly on an aggregate measure and exploiting career incentives based on disaggregated measures is smaller than the cost of contracting directly on disaggregate measures. Our findings also imply that detailed performance disclosures will be accompanied by lower incentive weights based on aggregate performance when career incentives mitigate distortions caused by aggregation. Further, if performance measures become noisier due to transient shocks, we find that contractual incentive weights on aggregate performance can be either increasing or decreasing, depending on the magnitude of a manager’s career incentives.
Geeksploitation: Optimism and Monitoring-Aversion in Agency Relationships
Authors: Smith Michael J.
Published: December 2010

ABSTRACT: This paper addresses the contracting implications of New Economy firms: informal, flexible organizations predominantly staffed by younger workers. The model incorporates two findings from the behavioral economics literature. First, workers may overestimate their own productivity (optimism). Second, workers may be monitoring-averse, with intense monitoring undermining intrinsic motivation. The combination of behavioral traits and work setting has deleterious consequences for workers. Despite higher monetary compensation and sometimes weaker incentives, they work harder in equilibrium, experience a higher disutility of effort than conventional workers, and also have a utility realization that is lower on average than their reservation utility. Optimism and monitoring-aversion are mutually reinforcing. When private information is introduced, both high- and low-productivity unconventional workers benefit, in contrast to standard agency models with asymmetric information. Both types of agents still experience a utility shortfall, however.
Controlled retrospective study of the effects of eyedrops containing phenylephrine hydrochloride and scopolamine hydrobromide on mean arterial blood pressure in anesthetized dogs
Authors: Martin-Flores Manuel , Mercure-McKenzie Tara M. , Campoy Luis , Erb Hollis N. , Ludders John W. , Gleed Robin D.
Published: December 2010

Objective—To determine whether dogs that received eyedrops containing phenylephrine and scopolamine would have a higher mean arterial blood pressure (MAP) when anesthetized than would dogs that did not receive the eyedrops.

Animals—37 nondiabetic and 29 diabetic dogs anesthetized for phacoemulsification and 15 nondiabetic dogs anesthetized for corneal ulcer repair (control dogs).

Procedures—Medical records were reviewed to identify study dogs. Dogs undergoing phacoemulsification received 2 types of eyedrops (10% phenylephrine hydrochloride and 0.3% scopolamine hydrobromide) 4 times during a 2-hour period prior to the procedure. Control dogs did not receive these eyedrops. Heart rate and MAP were measured before surgery in all dogs 10 and 5 minutes before, at the time of (t0), and 5 (t5) and 10 (t10) minutes after atracurium administration.

Results—MAP was greater in the 2 groups that received the eyedrops than in the control group at t0 and t5; at t10, it was greater only for the nondiabetic dogs that received eyedrops. Nine nondiabetic dogs and 1 diabetic dog anesthetized for phacoemulsification had at least 1 MAP value > 131 mm Hg; 73% of MAP values > 131 mm Hg were detected within 10 minutes after atracurium administration. At no time did a control dog have an MAP value > 131 mm Hg.

Conclusions and Clinical Relevance—Anesthetized dogs pretreated with eyedrops containing phenylephrine and scopolamine had higher MAP values than dogs that did not receive the eyedrops, suggesting the drops caused hypertension. Atracurium may interact with the eyedrops and contribute to the hypertension.
Effects of partial immersion in water on vertical ground reaction forces and weight distribution in dogs
Authors: Levine David , Marcellin-Little Denis J. , Millis Darryl L. , Tragauer Verena , Osborne Jason A.
Published: December 2010

Objective—To assess the impact of partial immersion in water on vertical ground reaction force (vGRF) and vGRF distribution in dogs.

Animals—10 healthy adult dogs.

Procedures—Weight placed on each limb of each dog was measured 3 times (1 scale/limb). Dogs were then immersed in water to the level of the tarsal, stifle, and hip joints, and vGRFs were measured. Coefficients of variation for triplicate measurements were calculated. Mixed-effects ANOVAs were used to compare the vGRF for thoracic versus pelvic limbs and the vGRF at various immersion levels as well as the vGRF distributions among limbs at various immersion levels.

Results—Mean ± SD vGRF before immersion was 249 ± 34 N. It was significantly decreased by 9% after immersion to the tarsal joints (227 ± 32 N), by 15% after immersion to the stifle joints (212 ± 21 N), and by 62% after immersion to the hip joints (96 ± 20 N). The vGRFs were significantly higher for the thoracic limbs than for the pelvic limbs before immersion and at all immersion levels. Dogs placed 64% of their weight on the thoracic limbs before immersion. That ratio did not differ significantly after immersion to the tarsus (64%) or stifle (63%) joints, but was significantly larger after immersion to the hip joints (71%).

Conclusions and Clinical Relevance—vGRF decreased as the depth of immersion increased. The thoracic limb-to-pelvic limb vGRF ratio was unchanged in dogs after immersion to the tarsal or stifle joints, but it increased after immersion to the hip joints.
Expression and function of 5-hydroxytryptamine 4 receptors in smooth muscle preparations from the duodenum, ileum, and pelvic flexure of horses without gastrointestinal tract disease
Authors: Prause Andrea S. , Guionaud Christophe T. , Stoffel Michael H. , Portier Christopher J. , Mevissen Meike
Published: December 2010

Objective—To evaluate the expression of the 5-hydroxytryptamine 4 (5-HT4) receptor subtype and investigate the modulating function of those receptors on contractility in intestinal tissues obtained from horses without gastrointestinal tract disease.

Sample Population—Smooth muscle preparations from the duodenum, ileum, and pelvic flexure collected immediately after slaughter of 24 horses with no history or signs of gastrointestinal tract disease.

Procedures—In isometric organ baths, the contractile activities of smooth muscle preparations in response to 5-hydroxytryptamine and electric field stimulation were assessed; the effect of tegaserod alone or in combination with 5-hydroxytryptamine on contractility of intestinal specimens was also investigated. Presence and distribution of 5-HT4 receptors in intestinal tissues and localization on interstitial cells of Cajal were examined by use of an immunofluorescence technique.

Results—Widespread 5-HT4 receptor immunoreactivity was observed in all intestinal smooth muscle layers; 5-HT4 receptors were absent from the myenteric plexus and interstitial cells of Cajal. In electrical field–stimulated tissue preparations of duodenum and pelvic flexure, tegaserod increased the amplitude of smooth muscle contractions in a concentration-dependent manner. Preincubation with tegaserod significantly decreased the basal tone of the 5-HT–evoked contractility in small intestine specimens, compared with the effect of 5-HT alone, thereby confirming that tegaserod was acting as a partial agonist.

Conclusions and Clinical Relevance—In horses, 5-HT4 receptors on smooth muscle cells appear to be involved in the contractile response of the intestinal tract to 5-hydroxytryptamine. Results suggest that tegaserod may be useful for treatment of reduced gastrointestinal tract motility in horses.
Leishmaniasis in a dog native to Colorado
Authors: Freeman Kate S. , Miller Matthew D. , Breitschwerdt Edward B. , Lappin Michael R.
Published: December 2010

Case Description—A 1-year-old 32.5-kg (71.5-lb) sexually intact male foxhound-Treeing Walker Coonhound cross was evaluated because of a 2.5-month history of dermatologic lesions, weight loss, and diarrhea.

Clinical Findings—Physical examination revealed muscle wasting, lymphadenopathy, and multifocal pruritic dermatologic lesions of alopecia, thickening, erythema, and follicular casting. Hematologic and serum biochemical analyses revealed nonregenerative anemia, mono-cytosis, hypercalcemia, hyperproteinemia, and hyperglobulinemia. Proteinuria was identified on urinalysis. Hepatomegaly, splenomegaly, and diffuse abdominal lymphadenomegaly were detected on abdominal ultrasonography. A diagnosis of leishmaniasis was confirmed by ELISA detection of serum antibodies against Leishmania spp, a high serum indirect fluorescent antibody titer (1:1,024) against Leishmania infantum, amplification of Leishmania DNA on PCR assay of a whole blood sample and a lymph node aspirate, and histologic identification of suspected Leishmania amastigotes in skin specimens. In addition, the dog had a low CD4+:CD8+ lymphocyte ratio of 1:1.

Treatment and Outcome—The dog was euthanized because of the severity of leishmaniasis and poor prognosis. This dog was from a litter of 10 puppies that included 4 stillborn puppies, 2 puppies that died as neonates, and 1 littermate that was euthanized at 1 year of age because of a high serum antibody titer against Leishmania spp. Eventually the foxhound dam was euthanized because of a high serum antibody titer against Leishmania spp. The dog had been raised with an unaffected littermate, its sire, and an unrelated Treeing Walker Coonhound female that were seronegative for Leishmania infection.

Clinical Relevance—Although vertical disease transmission was suspected, it is possible that L infantum is now endemic in Colorado. Leishmaniasis should be considered in dogs with scaly dermatoses.
The Implications of “Contamination” for Experimental Design in Education
Authors: Rhoads Christopher H.
Published: December 2010

Experimental designs that randomly assign entire clusters of individuals (e.g., schools and classrooms) to treatments are frequently advocated as a way of guarding against contamination of the estimated average causal effect of treatment. However, in the absence of contamination, experimental designs that randomly assign intact clusters to treatments are less efficient than designs that randomly assign individual units within clusters. The current article considers the case of contamination processes that tend to make experimental and control subjects appear more similar than they truly are. The article demonstrates that, for most parameter values of practical interest, the statistical power of a randomized block (RB) design remains higher than the power of a cluster randomized (CR) design even when contamination causes the effect size to decrease by as much as 10%–60%. Furthermore, from the standpoint of point estimation, RB designs will tend to be preferred when true effect sizes are small and when the number of clusters in the experiment is not too large, but CR designs will tend to be preferred when true effect sizes are large or when the number of clusters in the experiment is large.
Modern induced skull deformity in adults
Authors: Gump William
Published: December 2010

The practice of induced skull deformity has long existed in numerous disparate cultures, but for the first time in history it can be applied to adults. While extremely limited in application, some ideas have persisted in the far fringes of modern Western culture with remarkable tenacity. Practitioners of extreme body modification undergo procedures, outside the sphere of traditional medical practice, to make striking, permanent, nontraditional esthetic tissue distortions with the goal of transgressing societal norms. The International Trepanation Advocacy Group represents another example of a fringe cultural movement, whose goal, rather than being purely aesthetic in nature, is to promote elective trepanation as a method for achieving a heightened level of consciousness. Both movements have relatively short and well-defined histories. Despite their tiny numbers of adherents, neurosurgeons may be called on to address relevant patient concerns preprocedurally, or complications postprocedurally, and would benefit from awareness of these peculiar subcultures.