bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Sampling While Drilling Operations
Authors: Villareal S , Pop J , Bernard F , Harms K , Hoefel A , Kamiya A , Swinburne P , Ramshaw S
Published: February 2010

Although formation pressure-while-drilling (FPWD) tools have been introduced relatively recently the service is well accepted not only for its application to drilling optimization but also for reservoir characterization, especially in developed reservoirs. The next step in the progression of reservoir-related services to the drilling environment is clearly the acquisition of formation fluid samples while drilling. The while drilling environment, however, poses several potential challenges (and opportunities).For example: when should one sample, immediately after drilling the formation when the invasion is shallowest, or, after some time when the mud cake is more mature?; what is the effect of circulation rate on mud cake integrity?; and so on.

The first part of the paper describes a sampling-while-drilling (SWD) tool which is comprised of the following components: a probe module; a pumpout module, which has contained within it fluid property sensors, including a resistivity cell and a ten-channel optical spectrometer; a multi-sample module; and, a power generation module, consisting of a dedicated mud turbine and alternator which provides the required pumping power to the sampling tool.

The second part of the paper is devoted to the description and analysis of a series of tests which were performed to characterize sampling while drilling operations. In particular, the following aspects were studied for their effect on sampling efficiency and sample contamination: time after bit; mud circulation rate; ceasing and resuming pumping operations as a means of mitigating sticking risk during protracted pumping operations; and, captured sample integrity under drilling conditions.

All formations tested contained water as the formation fluid and the well was drilled with a water-based mud. Samples were acquired at multiple times during a single station and at multiple stations during the sampling operation in order to evaluate the effect of the test parameters on sample contamination and clean-up. To aid in the laboratory contamination analysis the mud was doped with bromine and iodine tracers. In addition, a water soluble blue dye was mixed with the mud to allow real-time monitoring of clean-up during pumping by means of the optical spectrometer. A wireline sampling tool was run after the while drilling tests were completed in order to compare the performance of the two sampling tools. In addition to the usual LWD logs, gamma ray, array resistivity, density-neutron and spectral gamma ray, a shallow array resistivity tool was run to quantify the extent of invasion at various times during the drilling/sampling operation.

The principal conclusions derived from the series of tests conducted are, that present-day sampling technology can be made to survive and operate effectively under drilling conditions and that there appear to be advantages to acquiring samples soon after drilling a formation.
Continuous Motion Rig: A Step Change in Drilling Equipment
Authors: Grinrod Mads
Published: February 2010

This paper outlines the technology and benefits of the continuous motion rig concept. This step change in drilling facilities technology is achieved through automation allowing any type of tubular to be pulled or run into the well without frequent intermittent stop in movement.

The continuous movement is enabled by mounting two lift systems in the derrick. The two systems work together in sequence comparable to pulling or lowering a rope continuously with both hands instead of working with only one hand. To be able to work a string with threaded joints in a continuous fashion up or down in the well the joints must be disconnected or connected while in continuous vertical movement. This implies that slips and tong must be mounted on each of the lift systems, taking string weight while connecting or disconnecting the coupling.

The basics and challenges of this system are outlined in the paper. When working in a continuous manner it is shown that even a slow continuous speed results in significant efficiency increases. A continuous slow drill pipe pulling speed of 0,5 m/sec results in tripping 1800 m/hr or app. 64 stands of 28m (app.90 ft) stands per hour. Doubling the speed to 1 m/sec, corresponding to app.peak pulling speed of today's drawworks in low gear, results in tripping speed of 3600m/hr.

One challenge of the system is to have technology in the vertical moving tongs to break connection and spin out in short enough intervals to avoid excessive height in the derrick.

Since string load is taken by the lift system off well center bending loads will be transferred to guide beams which must be given proper strength.

Other benefits of the continuous movement is minimizing problems normally connected with surge and swab effects due to lifting drill pipe out of slips and increasing pulling or lowering speed to peak and then brake down and stop. Further the problem of stuck pipe or casing caused by stop for connection is eliminated.
Gyro Guidance Techniques and Telemetry Methods Prove Economical in Onshore Multi-Well Pad Drilling Operations in the Piceance Basin
Authors: Garza Travis , Wimberg James , Woolridge Trevor , North Ezra , Beattie Keith
Published: February 2010

Wellbore collisions and accurate well placement are major concerns in Chevron U.S.A. Inc.’s multi-well pad drilling operations in the Piceance Basin in Colorado. Up to 24 wells are drilled from a single pad with two rows of well slots. As a result of the high well slot density, gyroscopic survey systems must be run during kickoff operations in most wells due to magnetic interference.

Several methods of obtaining high accuracy rate gyroscopic (gyro) survey data have been employed, including:

Rate Gyro single-shot surveys run on wireline; Gyro-While-Drilling (GWD) system incorporated in the Measurement-While-Drilling (MWD) string communicating with mud pulse telemetry; and GWD system incorporated in the MWD string communicating with electromagnetic (EM) telemetry.

This paper analyzes the performance of the three survey methods with respect to safety exposure, rig time, cost of service, equipment logistics, personnel requirements and operational performance. Field data is analyzed from more than 100 wells. This represents the largest database known by the authors for comparison of these service types presented in published literature.

Results indicate a solid justification for incorporating the gyro in the MWD string for the following reasons:

Saves rig time by eliminating the separate wireline; Decreases safety risk exposure by eliminating wireline operations; Minimizes risk of stuck bottomhole assembly (BHA) due to static operations during wireline surveying; EM technology when combined with the gyro creates an accurate, efficient, and reliable surveying system when compared with mud pulse-conveyed telemetry; Improved drilling control resulted from being able to steer continuously while drilling with the gyro in the MWD string; and Accurate well placement has decreased well collision exposure with no wellbore collisions to date.

Incorporating rate gyro systems in the MWD string while drilling has proven economical in the more costly offshore environment for a number of years (Eaton 2005). Applying the technology successfully to less expensive onshore projects can increase efficiency and bring additional benefits in reduced logistical requirements and safer operations.
Design Techniques for Reducing Toughness Related Cutter Issues in Carbonate Formations
Authors: Weeden Ryan W. , Whipple Justin
Published: February 2010

Carbonate formation drilling with PDC drill bits often leads to accelerated catastrophic diamond table loss of the PDC cutter. Historically, PDC toughness related failures have been blamed on the bit/formation interaction producing destructive drilling dysfunctions such as; axial, lateral, and torsional vibrations.

A number of design techniques have been applied to cutting structure/bit body design in an attempt to reduce the intensity and frequency of bit/formation interaction related drilling dysfunctions. These techniques were successful in reducing bit/formation interaction instigated drilling dysfunctions, however accelerated catastrophic diamond table failures were still observed at historical rates. This has led to the hypothesis that the accelerated catastrophic diamond table loss observed in carbonate formations is not exclusively related to drilling dysfunctions. The aforementioned hypothesis initiated a detailed study focusing on the relationship between cutting structure design and the damage observed from drilling carbonate formations. The results of this study clearly identified a relationship between hydraulic configuration, the relative magnitude and orientation of individual cutter’s impact force, and observed catastrophic diamond table failure.

Several experimental PDC drill bit designs were constructed using different hydraulic and cutting structure design techniques. These techniques were aimed at reducing the hydraulic erosion potential of cutter substrates and normalizing forces across the majority of the cutting structure. The product of these experimental bit runs has been incredibly positive. In every case, the optimized hydraulic configuration and impact force normalized cutting structure design has outperformed the control designs while drilling carbonate intervals.

This paper will focus on the performance differences between several control and experimental fixed cutter designs operating in the Anadarko Basin. The salient differences between these designs are the hydraulic configurations and the orientations of individual cutters on the control and experimental cutting structures. The slight modification of hydraulic configuration and individual cutter orientations (from control to experimental) has produced remarkable improvements in efficiency and durability. Several 7 7/8" diameter bit designs will provide the technical basis for this paper.
Comprehensive Studies of Aluminum Drillpipe
Authors: Tikhonov V. S. , Gelfgat M. Ya. , Cheatham Curis , Adelman Alex
Published: February 2010

Low weight, reduced bending stiffness and superior corrosion resistance combined with sufficiently high strength properties allow aluminum alloy drill pipe (ADP) to be used more extensively in drilling ultra-deep and extended-reach wells where corrosive environment may also be encountered.

This paper presents results of comprehensive studies of the most widely used LADP (Light Alloy Drill Pipe) 147×13 mm made from 1953T1 series aluminum alloy (Russian Grade). The studies involve the results of mechanical testing of small- scale specimens, corrosion testing in different media, fatigue testing of full-scale tool joint specimens, as well as finite- element analysis (FEA) of the "aluminum pipe – steel tool-joint" thread connection.

The results of the studies provide further evidence that use of LADP is entirely appropriate for drilling in many challenging environments.
Salinity-Based Pump & Dump Strategy for Drilling Salt with Supersaturated Fluids
Authors: Akers T. J.
Published: February 2010

Riserless drilling with weighted mud systems, commonly referred to as a "Pump & Dump" drilling strategy, is an established drilling technique used on deepwater wells with shallow hazards. Large holes and high flow rates result in very large volumes of fluid being required to drill to total depth (TD), circulate the well clean and cement the conductor casing string. Fluids management becomes a major issue in the riserless hole section. In the Gulf of Mexico, mud is often densified in excess of well requirements and then blended with seawater in a "Cut-Back" operation to reach the desired density to pump downhole.

When riserless drilling into salt, a Pump & Dump strategy is often used. Dilution with seawater, however, results in an undersaturated fluid. This fluid leaches the salt resulting in substantial hole enlargement. The hole enlargement can result in poor cementing jobs that require remediation or even an additional string of casing. A unique operation has been employed in the Santos Basin of Brazil where a supersaturated brine fluid was used to conduct a pump & dump operation with the goal of drilling with a saturated brine fluid and minimizing hole enlargement. This paper details the planning of the operation, fluid design, and pilot testing. Fluids management, equipment rig up, and results are discussed in detail. The operation has been successfully executed twice with both operations achieving the set objectives for the wells. Unforeseen complications that were encountered are discussed along with lessons learned that have been applied to subsequent operations.
Evaluation of Alternative Initial Responses to Kicks Taken during Managed Pressure Drilling
Authors: Davoudi Majid , Smith John Rogers , Patel Bhavin M. , Chirinos Jose E.
Published: February 2010

An industry-supported research project has completed its evaluation of alternative initial responses to kicks taken during the constant bottom hole pressure (CBHP) method of managed pressure drilling (MPD) operations. The evaluation is the first phase of a study that is intended to provide a basis for comprehensive, reliable well control procedures for MPD operations. The evaluation was based primarily on computer simulations of multiple alternative initial responses to several causes and severities of kicks in different well geometries. Three responses were concluded to have general application: increasing casing pressure until flow out equals flow in, shutting the well in, and using an adaptation of an MPD pump shut down schedule to detect and shut in low rate kicks.

A simple shut-in was concluded to be the most generally applicable response because it stops formation flow without requiring any special equipment. However, it also causes an increased risk of exceeding the formation fracture pressure for most situations versus a response that maintains continuous circulation. Increasing casing pressure while maintaining a constant pump rate until flow out equals flow in was concluded to be the most applicable response that avoids the disadvantages of shutting in the well. However, it requires accurate metering of return flow as a basis for determining whether formation flow has stopped. The adaptation of an MPD pump shut down schedule can be used to determine whether questionable kick indications are caused by a kick more conclusively than the other responses. It ends with the well being shut-in. A fourth response, increasing the pump rate, also has important but very limited application. The selection of which response is the most practical is shown to depend on well conditions and the equipment being used. Potential advantages of and constraints on the use of these responses are also explained.
Anchor Handling and Rig Move for Short Weather Windows During Exploration Drilling
Authors: Saasen Arild , Simpson Michael , Ribesen Bjørn Thore , Høj Jóanes
Published: February 2010

The paper describes field experience with a method for efficient anchor handling and rig move during North Sea exploration drilling campaigns with a semi submersible drilling rig requiring anchors for positional fix. A conventional anchor handling operation including a rig move operation is presented, followed by a detailed presentation of an innovative field operation including a method for combining anchor pick up, rig move and pre-setting. Four anchor handling boats were used to pick up anchors at an abandoned well. Thereafter the anchors and ground chains were sent off to next drilling location with three of the boats. These boats pre-set the anchors. The anchor pre-setting sequence was selected such that one boat was released after only a short period at the new location.

The last anchor handling vessel, the smallest one, was used in the rig move operation as a tug. When the rig arrived at the new drilling location, the three remaining boats were involved in connecting the anchors. As a result of the pre-set anchors, the mooring operation could be performed in a weather window, being roughly one half of the weather window needed for normal mooring operations. The anchor handling boats were released sequentially as early as possible reducing the cost of the entire operation significantly. As will be described a traditional anchor handling operation would have resulted in two days waiting on weather in addition to the extra time spent on anchor handling because the weather conditions deteriorated. The paper also describes the challenges of retrieving pre-laid anchors tensioned to the anticipated maximum 100 years load.
Large-Volume Cement Squeezes as Cost-Effective Solutions for Severe-Loss Zones
Authors: Algu Devendra , Galey Loran , Barrett Myles , Humphries Mike
Published: February 2010

Loss circulation is commonly induced while drilling wells through depleted intervals. The combination of narrow margin between formation pore pressure and fracture pressure makes loss circulation inevitable in many wells. Pretreatment of the drilling fluid with loss-circulation material while drilling and wellbore strengthening techniques have successfully reduced instances of high-rate, large-volume (>1000 bbl) losses.

Fracture width and volume created by high-rate, large-volume losses often limit the effectiveness of conventional loss- circulation treatments for two reasons. First, the size and concentration of bridging materials that will effectively bridge the fracture opening can plug the bottomhole drilling assembly. A trip may be required to remove the bit and other components of the bottomhole drilling assembly. If losses are severe, this trip may not be possible without risk to well control. Second, it is difficult to restore and maintain wellbore strength to a level equivalent to the integrity prior to losses, especially if substantial openhole drilling time is required to reach the next casing point.

This paper presents the design strategy, formulations and testing requirements, placement techniques and procedure, and other practices utilized in successful large-volume cement squeezes to remediate severe, high-rate, large-volume losses. Results from two deepwater case studies will be presented to illustrate successful application of this treatment approach. Cement squeezes can be performed through many bottomhole drilling assemblies, where conditions require, and eliminate the dependence of success on correct sizing of bridging particles. Large-volume, specially designed cement squeezes have proven effective methods to restore wellbore integrity after loss rates as high as 320 to 480 bbl/hr and total volume of losses to the formation of up to 4000 bbl prior to treatment.
Pressure Transmission in Gelled Drilling Fluids in Deepwater Environments
Authors: Negrão C. O. , Franco A. T. , Oliveira G. M. , Martins A. L. , Gandelman R. A. , Rocha L. L.
Published: February 2010

Deep water drilling is normally associated to narrow operational windows where gains and losses are frequent. drilling fluids are designed to gel when it is not submitted to shear stress. This is necessary to avoid cuttings to settle during circulation stops. When circulation is resumed, the pump pressure rises above the circulation pressure in order overcome the gel strength. Due to its thyxotropic effect, the gel viscosity remains high for a while after the circulation restart. The gelation may have significant importance, specially, in deep waters where high pressures and low temperatures take place. Gel effects can both generate excessive pressures (inducing losses) and cause delays in pressure transmission which can directly affect gain detection devices. The current work presents a compressible transient flow model of the restart of drilling fluid circulation, in order to predict pressures at the borehole. The model comprises the conservation equations of mass and momentum which are solved by the finite volume method. A constitutive equation is employed to model the time dependent rheology of gel breaking. Case studies are conducted to evaluate the effect of fluid properties, well geometry and pumping pressure on the bottomhole pressures. Major effects on pressure propagations delay in deepwater drilling are highlighted.
Total System Optimization Delivered Significant Performance Improvement and Cost Savings in GoM Challenging Salt Section
Authors: Voss W. , Aslakson J. , Thomson I. , Radford S. , Thomson C. , Buxton B.
Published: February 2010

It is well known in the oil industry that there are many drilling challenges associated with salt drilling in the Gulf of Mexico continental shelf. Although many wells have already been drilled through salt, hazard prediction is still not very accurate, which makes extensive planning a critical requirement. While drilling a prior well through a thick salt body in the shallow waters of the Gulf of Mexico Ship Shoal area, the operator experienced many drilling-related problems, including numerous downhole tool failures, leading to considerable non-productive time (NPT) and additional costs. This paper will focus on the planning and execution of a sidetrack to this problematic well, again drilled through and exiting the salt. This paper highlights the problems encountered and the substantial cost savings realized by the operator.

During the planning phase, a thorough offset analysis was conducted using an engineered optimization process, which allowed the identification of the root causes for the downhole tool failures and mapping of the main drilling hazards. The main drilling challenge in this project was to drill and underream efficiently through anhydrite layers imbedded in the thick salt body. In the offset well, most of the drilling problems were associated with these anhydrite layers, which induced significant vibration and premature cutting structure damage. Location and thickness of the anhydrite layers were difficult to predict, therefore pre-established drilling procedures and best practices were key to help identify the anhydrite layer promptly and successfully overcome it.

The implementation of a multi-discipline total system approach to select the ideal combination of an application-specific rotary steerable system, real-time downhole drilling dynamics tool, drill bit and underreamer, in combination with appropriate planning, recommendations, drilling procedures, and best practices was crucial to deliver significant performance improvement by drilling the sidetrack salt section six days ahead of AFE, which represented US $2.1 million in savings for the operator.
Electromagnetic MWD Technology Improves Drilling Performance in Fayetteville Shale of North America
Authors: Janwadkar S. , Klotz C. , Welch B. , Finegan S.
Published: February 2010

The Fayetteville Shale is one of the newest and fastest-growing shale gas plays gaining significant prominence in North America. This unconventional reservoir is located in the Arkoma basin of Arkansas. Drilling horizontal wells coupled with hydraulic fracturing makes this reservoir highly prolific and comparable to the Barnett Shale. However, the area presents numerous challenges including loss of circulation, wellbore instability, and significant connection times reducing efficiency while drilling the curve and lateral sections.

To address these challenges, a detailed engineering analysis was performed using a proven drilling optimization procedure. As a result of the study, engineers determined that surface pressure limitations with high rates of penetration (ROP), together with pumping of loss circulation material (LCM) to control fluid losses negatively affected the performance of downhole measurement while drilling (MWD) equipment. Existing standard mudpulse technology could not operate efficiently while drilling with loss circulation, no fluid returns or high LCM concentrations. Wired-pipe technology is typically cost- prohibitive in this application.

An electromagnetic (EM) MWD system was used and the transmission of real-time data was done via EM signals through the formation instead of fluid pressure pulses through the inner bore of the pipe. The system was designed to provide accurate real-time MWD data and reliable directional control and was not hindered by the presence of multi-phase fluids, high-density solids, or LCM in the wellbore.

The results achieved are 33% to 36% increase in the average ROP and 13% reduction in drilling time to reach target depths. The authors will describe the significance of applying principles of EM technology to improve drilling performance.
An Experimental Study to Define Operational Parameters Governing Hole Enlargement While Drilling Offshore Heavy-Oil Reservoirs
Authors: da Costa F. G. , Ferreira M. V. , Campos E. F. , Macedo F. S. , Aragão A. F. , Martins A. L.
Published: February 2010

The development of heavy oil fields imposes several challenges for well construction: in order to guarantee minimum flow rates, long horizontals intervals are often required. Long horizontals are associated to long reservoir exposure times which can affect final open hole quality. Rock fluid interaction issues and BHA design directly affect the drilling of sensitive formations, such as non consolidated heavy oil reservoirs.

This article presents initially a comprehensive data analysis of caliper logs in offshore heavy oil wells drilled in Brazil. The analysis correlates hole enlargement with relevant parameters such as fluid type, flow regime and BHA composition. Data sources considered were real time monitoring equipment, logging data and drilling reports. Results indicate that water based fluids and turbulence proved to stimulate hole enlargement and should be avoided.

The study is also supported by a unique experimental work where fluid flow conditions were simulated in a pilot unit where the wellbore was represented by a non consolidated synthetic core saturated with high viscosity oil. For a given flow rate, hole enlargement is monitored with time by a real time CT scanning technique. Experimental results are in agreement with field observations. The role of drillstring composition was not contemplated in the experimental study.
An Intelligent System to Detect Drilling Problems Through Drilled Cuttings Return Analysis
Authors: Marana A. N. , Guilherme I. R. , Papa J. P. , Ferreira M. V. , Miura K. , Torres F. A.
Published: February 2010

Cuttings return analysis is an important tool to detect and prevent problems during the petroleum well drilling process. Several measurements and tools have been developed for drilling problems detection, including mud logging, PWD and downhole torque information. Cuttings flow meters were developed in the past to provide information regarding cuttings return at the shale shakers. Their use, however, significantly impact the operation including rig space issues, interferences in geological analysis besides, additional personel required.

This article proposes a non intrusive system to analyze the cuttings concentration at the shale shakers, which can indicate problems during drilling process, such as landslide, the collapse of the well borehole walls. Cuttings images are acquired by a high definition camera installed above the shakers and sent to a computer coupled with a data analysis system which aims the quantification and closure of a cuttings material balance in the well surface system domain. No additional people at the rigsite are required to operate the system.

Modern Artificial intelligence techniques are used for pattern recognition and data analysis. Techniques include the Optimum-Path Forest (OPF), Artificial Neural Network using Multilayer Perceptrons (ANN-MLP), Support Vector Machines (SVM) and a Bayesian Classifier (BC). Field test results conducted on offshore floating vessels are presented. Results show the robustness of the proposed system, which can be also integrated with other data to improve the efficiency of drilling problems detection.
Mesophase Spacer Designs Raise the Bar for Casing and Riser Clean-up in Deepwater Applications
Authors: Quintero Lirio , Christian Chad , Jones Thomas A.
Published: February 2010

When displacing and completing oil and gas wells in deepwater, contaminants, such as oil-base drilling fluids, drilled solids, pipe dope and other debris found in casing and risers, should be removed quickly and efficiently to avoid excessive operating costs and to minimize formation damage during the completion phase. Synthetic-based invert emulsion drilling fluid debris is considered the most difficult to remove and typically requires excessive rig time to filter brine to appropriate levels of clarity using conventional spacer systems. These unscheduled costs and delays can be avoided if the displacement and clean-up spacers are properly designed.

A properly designed displacement spacer system should remove all foreign debris, completely water-wet all metal surfaces in a single pass of the spacer train and require no more than a single circulation of completion brine. The spacers should also be formulated to (1) have superior detergency at cold seabed and downhole temperatures, (2) prevent viscous emulsions or sludge, and (3) be compatible with the drilling fluid to prevent channeling.

Using mesophase technology which is a surface-active additive package (SAAP), a new spacer system has been developed and tested that does not require the use of common organic solvents or terpenes. Additionally, the new system is simple to apply and reduces non-productive time (NPT). This novel two-spacer system has been successful in several deepwater applications, demonstrating its ability to efficiently clean the riser, casing, and wellbore clean-up tools. The displacement spacer system has been successfully applied during direct and indirect displacements of synthetic-based drilling fluids.

This paper will discuss the challenges and successes of displacing synthetic-based mud in deepwater applications and the lessons learned.
Who Needs Grief Counseling? A Report from the Scott & White Grief Study
Authors: Gamino Louis A. , Sewell Kenneth W. , Hogan Nancy S. , Mason Saundra L.
Published: February 2010

Cluster analysis was performed on a diverse group of 69 non-clinical grievers whose loved ones died between 12–40 months prior to the study. Based on psychometric measures of both bereavement distress and growth, three distinct clusters emerged: High Grief (high distress—low growth; n = 16); High Growth (low distress—high growth; n = 32); and Low Impact (low distress—low growth; n = 21). Discriminant function analyses showed that the High Grief cluster differed robustly from the other two groups on several measures of grief adaptation and coping; the differences between the High Growth and Low Impact clusters were less pronounced. High Grief participants sought grief counseling significantly more often whereas the Low Impact grievers preferred medicinal help for symptoms if they sought any professional assistance at all. When High Growth participants sought counseling, they seemed to focus on growth-oriented dimensions rather than mere symptom relief. Of the 11 participants who sought grief counseling for their loss, 10 (91%) found the experience to be helpful. Findings are discussed in the context of meta-analytic studies of the effectiveness of grief counseling.
Evaluating Reforms in Canadian Chicken Marketing Mechanisms Using a Linear-Quadratic Inventory Model
Authors: Abbassi Abdessalem , Gervais Jean-Philippe
Published: February 2010

Marketing institutions in supply managed industries are evolving due to broad globalization pressures. The output and sales decisions of chicken processing firms under two different pricing mechanisms are modeled using a linear-quadratic inventory model. Decision rules lead to structural equations that relate output and sales to their own lagged values, lagged inventories and lagged prices and cost indicators. A Generalized Method of Moments (GMM) estimator is applied to the system of equations. The null hypotheses no adjustment costs in processing and no role for inventories in marketing are rejected. We simulate the impacts of reforming the chicken pricing mechanism, moving from producers vs. processors bargaining to a formula-based price (referred to as cost-plus"). Output in the industry is higher under the bargaining pricing system mostly because processors pay a lower price than under the cost-plus" mechanism. Simulations reveal that producers' expected profits are lower on average under the bargaining system than under cost-plus." Moreover, the cost-plus" system reduces the variability of profits.
A new species of Mathevotaenia (Cestoda, Anoplocephalidae, Linstowiinae) from the lizard Sceloporus malachiticus (Squamata, Phrynosomatidae) from Panama
Authors: Bursey Charles , Goldberg Stephen , Telford Sam
Published: February 2010

Mathevotaenia panamaensis sp. nov. (Cestoda, Anoplocephalidae, Linstowiinae) from a green spiny lizard, Sceloporus malachiticus, collected in Panama is described. This is the first species of Mathevotaenia reported from a lizard host. The new species is most similar to Mathevotaenia bivittata in that mature eggs are concentrated along the lateral margins of the proglottids. Major differences between the two species include oval cirrus sac in M. bivittata, a spherical cirrus sac in M. panamaensis; ovary compact consisting of 10–15 short lobules in M. bivittata, ovary bilobed with each lobe consisting of 3–4 lobules in M. panamaensis.
Some trichinelloid nematodes from marine fishes off New Caledonia, including description of Pseudocapillaria novaecaledoniensis sp. nov. (Capillariidae)
Authors: Moravec František , Justine Jean-Lou
Published: February 2010

Examinations of materials of trichinelloid nematodes recently collected from the digestive tract of marine fishes off New Caledonia, South Pacific, revealed the presence of several species of the families Capillariidae and Trichosomoididae, including capillariids Pseudocapillaria novaecaledoniensis sp. nov. from the deep-sea Pristipomoides argyrogrammicus (Valenciennes) (Lutjanidae) and Pseudocapillaria echenei (Parukhin, 1967) from Echeneis naucrates Linnaeus (Echeneidae), and the trichosomoidid Huffmanela sp. (female) from Bodianus perditio (Quoy et Gaimard) (Labridae). P. novaecaledoniensis is characterized mainly by the structure and length (318–321 µm) of spicule and the presence of a dorsal cuticular membrane interconnecting both ventrolateral caudal lobes in the male (subgenus Ichthyocapillaria Moravec, 1982). The previously poorly known P. echenei is redescribed and recorded for the first time from the South Pacific Ocean. In addition, five morphologically different types of capillariid females without generic identification, designated as Capillariidae gen. spp. 1–5, each of them probably representing a new species, were recorded from Fistularia commersonii Rüppell (Fistulariidae), Synodus dermatogenys Fowler (Synodontidae), Carangoides oblongus (Cuvier) (Carangidae), Diagramma pictum (Thunberg) (Haemulidae) and Stegostoma fasciatum (Hermann) (Stegostomidae), respectively. Capillaria decapteri is transferred to Pseudocapillaria Mendonça, 1963 as P. decapteri (Luo, 2001) comb. nov.
Helminth parasites (Cestoidea, Nematoda, Pentastomida) of selected herpetofauna from Cameroon, West Africa
Authors: McAllister Chris , Bursey Charles , Freed Paul
Published: February 2010

Twenty-nine individual amphibians (2 families, 3 species) and 12 individual reptiles (2 families, 2 species) from Douala, Cameroon (West Africa) were examined for helminths. Seventeen (59%) of the amphibians and 11 (92%) of the reptiles were found to harbor at least 1 species of helminth; 10 (34%) of the amphibians and 4 (33%) of the infected reptiles harbored multiple infections. A cestode, 6 species of nematodes, and a pentastomid were found in the herpetofauna surveyed. Nine new host and six new geographic distribution records are reported.
Prevalence of Toxoplasma gondii antibodies in cats in maiduguri, northeastern nigeria
Authors: Kamani Joshua , Mani Aliyu , Kumshe Hussaini , Yidawi James , Egwu Godwin
Published: February 2010

Cats play an important role in the spread of Toxoplasma gondii because they are the only animals that excrete resistant oocysts into the environment. Prevalence of T. gondii antibodies in cats in Maiduguri, Northeastern Nigeria was determined using the latex agglutination test (LAT). Thirty eight cats (36.2%) were seropositive using a cut off point of 1:64 with antibody titer ranging from 1:64 to 1:1024. Seroprevalence was higher in older animals and stray cats. Age and ownership status of cats were identified as risk factors but not gender or area of capture.
Linguistic Structure, Stylistic Value, and Translation Strategy: Introducing Thomas Mann's Aschenbach in English
Authors: Horton David
Published: February 2010

By analysing closely two English versions of the opening passage of Der Tod in Venedig, this discussion addresses implications arising from the interlingual transfer of syntactic structures in literary texts. Even the most cursory glance at a translation corpus shows that prose translators - subject to language-typological constraints in syntactic possibilities - are generally concerned to mirror the sentence structures of the SLT in the syntactic composition of their TL versions. Here the contention is that, on the contrary, translation solutions cannot be ‘equivalent’ to the original at the level of complex syntax. Rather, translators inevitably make changes which significantly alter the information focus, agency patterns, and cohesion of the original, impacting on the literary meaning in subtle ways.
Using Fuzzy Logic to Enhance Stereo Matching in Multiresolution Images
Authors: Medeiros Marcos  D. , Gonçalves Luiz Marcos  G. , Frery Alejandro  C.
Published: February 2010

Stereo matching is an open problem in Computer Vision, for which local features are extracted to identify corresponding points in pairs of images. The results are heavily dependent on the initial steps. We apply image decomposition in multiresolution levels, for reducing the search space, computational time, and errors. We propose a solution to the problem of how deep (coarse) should the stereo measures start, trading between error minimization and time consumption, by starting stereo calculation at varying resolution levels, for each pixel, according to fuzzy decisions. Our heuristic enhances the overall execution time since it only employs deeper resolution levels when strictly necessary. It also reduces errors because it measures similarity between windows with enough details. We also compare our algorithm with a very fast multi-resolution approach, and one based on fuzzy logic. Our algorithm performs faster and/or better than all those approaches, becoming, thus, a good candidate for robotic vision applications. We also discuss the system architecture that efficiently implements our solution.
Contingent Diversity on Anthropic Landscapes
Authors: Balée William
Published: February 2010

Behaviorally modern human beings have lived in Amazonia for thousands of years. Significant dynamics in species turnovers due to human-mediated disturbance were associated with the ultimate emergence and expansion of agrarian technologies in prehistory. Such disturbances initiated primary and secondary landscape transformations in various locales of the Amazon region. Diversity in these locales can be understood by accepting the initial premise of contingency, expressed as unprecedented human agency and human history. These effects can be accessed through the archaeological record and in the study of living languages. In addition, landscape transformation can be demonstrated in the study of traditional knowledge (TK). One way of elucidating TK distinctions between anthropic and nonanthropic landscapes concerns elicitation of differential labeling of these landscapes and more significantly, elicitation of the specific contents, such as trees, occurring in these landscapes. Freelisting is a method which can be used to distinguish the differential species compositions of landscapes resulting from human-mediated disturbance vs. those which do not evince records of human agency and history. The TK of the Ka’apor Indians of Amazonian Brazil as revealed in freelisting exercises shows differentiation of anthropogenic from high forests as well as a recognition of diversity in the anthropogenic forests. This suggests that the agents of human-mediated disturbance and landscape transformation in traditional Amazonia encode diversity and contingency into their TK, which encoding reflects past cultural influence on landscape and society over time.
Long-Term Human Induced Impacts on Marajó Island Landscapes, Amazon Estuary
Authors: Schaan Denise
Published: February 2010

Archaeology is a discipline that can offer a long term perspective on the impacts human societies have had on the environment. Landscape studies are critical for understanding these impacts, because they embrace a dialectical view regarding the relationship between humans and their immediate surroundings. Such studies are well suited to the Amazon basin, a region that has driven much media attention due to astonishing rates of deforestation in certain areas, with likely consequences on the planet’s climate, posing challenges to the survival of the human species for the coming decades. In fact, although much has been said about the impacts of contemporary societies on tropical forest environments, ancient landscape management practices have not yet been considered part of the equation. Thus far, we know that Amerindian societies have been actively transforming their surroundings for millennia. On the eve of European contact, large, complex societies were bringing about long-lasting transformations of landscapes throughout the basin. Conquest and colonization resulted in epidemics, enslavement, and changes to the indigenous economies that managed to survive the genocide. Afterwards, as colonizers would exploit traditional resources leading, in many instances, to their exhaustion, a huge quantity of information on sustainable ways of dealing with certain environments became lost. Traditional knowledge, however, still survives among certain indigenous, peasant (caboclo), and African-Brazilian populations. Documentation of surviving management practices together with the study of the archaeological record could provide valuable information for policy makers. This article examines historical transformations that took place on Marajó Island during the last two millennia and advocates the importance of archaeological research for understanding the historical ecology of landscape change. It is argued that ancient economic strategies, some still being practiced today, could be re-created in the present, since these may constitute opportunities for sustainable sources of income to local communities.
A Methodology for Modelling Canopy Structure: An Exploratory Analysis in the Tall Wet Eucalypt Forests of Southern Tasmania
Authors: Scanlan Ian , McElhinny Chris , Turner Perpetua
Published: February 2010

A ground-based methodology is presented for spatially modelling forest canopy structure. Field measurements and allometric relationships are used to predict the profiles of free-growing tree crowns on the basis of stem diameter at breast height (dbh). These profiles are incorporated into three-dimensional canopy models using AutoCAD™ technical drawing software and field data describing the genus, dbh and relative positions of all trees greater than 10 cm dbh; critically, our models account for the effects of competition for light between neighbouring crowns. By horizontally partitioning the models, the presence of distinct strata and the dominant genera associated with each stratum can be identified. Our methodology is applicable to other forest ecosystems as a research tool for investigating changes in vertical structure, and for calibrating remote sensing technologies in order to map and monitor canopy structural variation across forested landscapes.
Dinitrogen and Related Chemistry of the Lanthanides: A Review of the Reductive Capture of Dinitrogen, As Well As Mono- and Di-aza Containing Ligand Chemistry of Relevance to Known and Postulated Metal Mediated Dinitrogen Derivatives
Authors: Gardiner Michael G. , Stringer Damien N.
Published: February 2010

This paper reviews the current array of complexes of relevance to achieving lanthanide mediated nitrogen fixation. A brief history of nitrogen fixation is described, including a limited discussion of successful transition metal facilitated nitrogen fixation systems. A detailed discussion of the numerous lanthanide-nitrogen species relevant to nitrogen fixation are discussed and are related to the Chatt cycle for nitrogen fixation.
Performance of Zirconia for Dental Healthcare
Authors: Silva Nelson R.F.A. , Sailer Irena , Zhang Yu , Coelho Paulo G. , Guess Petra C. , Zembic Anja , Kohal Ralf J.
Published: February 2010

The positive results of the performance of zirconia for orthopedics devices have led the dental community to explore possible esthetical and mechanical outcomes using this material. However, questions regarding long-term results have opened strong and controversial discussions regarding the utilization of zirconia as a substitute for alloys for restorations and implants. This narrative review presents the current knowledge on zirconia utilized for dental restorations, oral implant components, and zirconia oral implants, and also addresses laboratory tests and developments, clinical performance, and possible future trends of this material for dental healthcare.
Chemical Analysis and Biological Activity of the Essential Oils of Two Endemic Soqotri Commiphora Species
Authors: Mothana Ramzi A. , Al-Rehaily Adnan J. , Schultze Wulf
Published: February 2010

The barks of two endemic Commiphora species namely, Commiphora ornifolia (Balf.f.) Gillett and Commiphora parvifolia Engl., were collected from Soqotra Island in Yemen and their essential oils were obtained by hydrodistillation. The chemical composition of both oils was investigated by GC and GC-MS. Moreover, the essential oils were evaluated for their antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria and one yeast species by using a broth micro-dilution assay for minimum inhibitory concentrations (MIC) and for their antioxidant activity by measuring the DPPH radical scavenging activity. A total of 45 constituents of C. ornifolia (85.6%) and 44 constituents of C. parvifolia (87.1%) were identified. The oil of C. ornifolia was characterized by a high content of oxygenated monoterpenes (56.3%), of which camphor (27.3%), α-fenchol (15.5%), fenchone (4.4%) and borneol (2.9%) were identified as the main components. High contents of oxygenated sesquiterpenes (36.1%) and aliphatic acids (22.8%) were found in C. parvifolia oil, in which caryophyllene oxide (14.2%), β-eudesmol (7.7%), bulnesol (5.7%), T-cadinol (3.7%) and hexadecanoic acid (18.4%) predominated. The results of the antimicrobial assay showed that both oils exhibited moderate to high antibacterial activity especially against Gram-positive bacteria. C. ornifolia oil was the most active. In addition, the DPPH-radical scavenging assay exhibited only weak antioxidant activities for both oils at the high concentration tested.
Facile Synthesis and Preferred Conformation Analysis of Cyclododeceno[b]indene
Authors: Zhang Chunyan , Gong Shengyan , Zhang Li , Wang Daoquan , Wang Mingan
Published: February 2010

Using methanesulfonic acid as a catalyst, a series of cyclododeceno[b]indene derivatives were synthesized by the cyclization of α-benzylcyclododecanones, which were prepared by the reactions of cyclododecanones with a variety of substituted benzyl chlorides or bromides using NaH as a base. Their structures were confirmed by mp, IR spectra, 1H-NMR, 13C-NMR, MS, and x-ray diffraction. The preferred conformations were analyzed by crystal structure, 1H-NMR and quantum chemistry calculations, and compared with the x-ray diffraction structure of 2,3,5,6-bis(ortho-1,10-decylidene)dihydropyrazine. The results showed that the cyclododecene moiety adopted a preferred [1ene2333] conformation, and the substituted groups at aromatic ring had no significant influence on the conformation.