bluuebunny/crossref_metadata_2025 huggingface dataset:
Deconvolution of Multiwell Test Data
Authors: Levitan Michael M.
Published: January 2008

The deconvolution analysis technique that evolved with development of the deconvolution algorithms by von Schroeter et al. (2004), Levitan (2005), and Levitan et al. (2006) became a useful addition to the suite of techniques used in well-test analysis. This deconvolution algorithm, however, is limited to the pressure and rate data that originate from a single active well on the structure. It is ideally suited for analysis of the data from exploration and appraisal well tests. The previously mentioned deconvolution algorithm can not be used with the data that are acquired during startup and early field development that normally involve several producing wells.

The paper describes a generalization of deconvolution to mul-tiwell pressure and rate data. Several approaches and ideas for multiwell deconvolution are investigated and evaluated. The paper presents the results of this investigation and demonstrates performance of the deconvolution algorithm on synthetic multiwell test data.
The Resiliency of Frac-Packed Subsea Injection Wells
Authors: McCarty R. A. , Norman W. D.
Published: January 2008

This paper documents the utilization of fracpack completion technology for water injectors in sand control environments. This paper is a look back after five years of operation. It includes a review of the goals of the project and issues that occurred during the operation of the field. There is a discussion of the influence of the installation execution quality, the resulting injectivity index, analysis of the Hall Plot for the wells, analysis of the pressure decline from recent field shut-in, assesses the injection pressure versus the fracture pressure and comments on the tubing change out workovers. The results indicate that the fracpack completions are a very resilient and robust sandface completion for injectors. They have allowed injection below fracture pressure even after five years of injection with more than 400 emergency shut downs, cross flow, and filtration bypass.
Gas-Lift Hybrid Application in Offshore Northwest Java Production Sharing Contract
Authors: Santoso B. T. , Priyandoko P. , Harahap Boyke
Published: January 2008

Wells in X-ray area of Northwest Java Production Sharing Contract were all produced by Electrical Submersible Pump (ESP) system until gas zone was discovered in XM area in 1987. During development drilling, gas zone was discovered in XM structure 4 miles from the southern portion of XA filed. The gas zone was tested to be sufficient in term of pressure and gas volume for the support of a local gas lift project. The gas zone were then completed as a source gas to supply gas lift for all the XMA wells. Recently, the source gas has somewhat depleted to maintain all the production wells in that area. For that reason, several wells need to be selectively shut in. As pressure of gas depletes, the conversion from gas lift (GL) to ESP wells, as primary artificial lift mechanism is required. To minimize the down time period during ESP change out, ESP- GL hybrid was proposed to take the advantage of the limited source gas availability. This action allows the wells to continue on production while scheduling a pulling unit to replace the failure ESP.
Geometry, Internal Heterogeneity and Permeability Distribution in Turbidite Reservoirs, Pliocene California
Authors: Davies D. K. , Hara P. S. , Mondragon J. J.
Published: January 2008

This paper presents a reservoir model of the geometry, internal heterogeneity and permeability distribution in deep water, unconsolidated turbidite sand reservoirs of Wilmington Field, California. These reservoirs were deposited in a variety of environments associated with a deep-sea submarine fan system. The external form and internal heterogeneity of the reservoirs is controlled fundamentally by depositional environment. Production (rate and volume) is anisotropic and parallels the depositional trends. Production data indicate relatively high sweep efficiency and preferential permeability in a NE-SW direction (down depositional dip). Permeability and porosity are only weakly related to grain size. Sorting (standard deviation of grain size) and skewness (asymmetry of the grain size distribution) are the fundamental controls on porosity and permeability.

Rock-based log models of permeability and internal reservoir heterogeneity are developed based on detailed integration of core and wireline log data, specifically data related to pore geometry. Development drilling demonstrates that areas of the field with the highest values of porosity x thickness (PhixH) and lowest water saturation x thickness (SwxH) do not necessarily have the highest permeability and productivity. Areas with high productivity can have moderate values of PhixH and SwxH, but are characterized by high values of permeability x thickness.

In high porosity turbidite reservoirs, pore geometry based log models of permeability and reservoir heterogeneity allow for improved petrophysical evaluation, specifically net pay determination and prediction of producibility.
Identifying and Evaluating Producing Horizons in Fractured Basement
Authors: Tandom P. M. , Ngoc N. H. , Tjia H. D. , Lloyd P. M.
Published: January 2008

This paper will describe the results of development drilling to date in the basement reservoir of the Ruby Field in the Mekong Basin, Offshore Vietnam.

The results of joint research on the Ruby discovery wells and onshore basement exposures (Peter M. Tandom et al. 1997) were used to develop an interpretation model for the fractured and weathered granite reservoir. This model has proven very robust, and has now been further enhanced by applying more quantitative formation evaluation techniques to determine fracture aperture and porosity. Various acquisition techniques and computation algorithms have been tested to come up with an optimized logging program; giving consistent results compared with core analysis and production data.

It is now possible to predict with some certainty the most prospective hydrocarbon bearing intervals, and work is currently being focused on the estimation of likely production rates. Failure to meet the expected well deliverables provides a criteria for identifying candidates for stimulation. These techniques will also be reviewed.

As more wells are drilled, it has become possible to better correlate and map the producing horizons. This clearly allows better planning of the location of future wells, and the thickness of the reservoir section which needs to be penetrated, so optimizing field economics.
Best Practice Methods For Offshore Pipeline Installation In Sensitive Shallow Water Marine Environments
Authors: Hyams M. , Gorham R. , Howitt L. , Dixon K.
Published: January 2008

This paper outlines the environmental management controls successfullyimplemented during the construction of two offshore mini-platforms andassociated pipelines located in environmentally sensitive shallow tropicalmarine waters in the North West Shelf area of Western Australia.

The innovative barge anchoring methods implemented during the installationof the pipelines were successful in ensuring that no significant damageoccurred to the 1,300 coral bomboras surveyed within both pipelinealignments.

These projects serve as a case study demonstrating that the installation ofpetroleum facilities can be successfully undertaken in sensitive marineenvironments with no adverse environmental impacts on sensitive seabed habitats.
Is Your HS&E Management System Effective?
Authors: Brasher Ana , Featherly Janey
Published: January 2008

Today's business climate requires higher production levels at a competitive price while ensuring our business activities create no harm to people or the environment. To achieve this goal most companies have selected the HS&E Management System Approach based on the ISO 14001, OHSAS 18001 and Plan, Do, Check, Act principles. But how do you determine if your management system is adequate and effective to produced desired outcomes?

This paper will explore the ways that effective management systems are monitored on an ongoing basis and how that data is used to determine effectiveness of the system and drive continual improvement. Reviewing of the system begins with linking the commitments of an organization's policy statement to business objective. After this relationship has been identified appropriate performance measures are selected which allow management to monitor and evaluate the effectivness of the system. Finally, how are the commitments from the policy, business objectives and performance measures used to determine whether the system is adequate and effective to continually improve performance.
Drilling Wellbore Stability in the Compacting and Subsiding Valhall Field: A Case Study
Authors: Kristiansen Tron Golder
Published: January 2008

Valhall is a field development located in the southernmost part of the Norwegian Continental Shelf. The chalk reservoir is weak and started to compact when oil production was initiated in 1982. The reservoir compaction was soon after observed at the seafloor in form of seafloor subsidence. Drilling was initially not a major challenge at Valhall, but as the reservoir depletion, compaction, and subsidence continued through the 90s, one had to develop drilling strategies to handle the associated reduction in frac gradient in the reservoir as well as the increasing problems experienced in high-angle ERD wells in the overburden. The problems in the overburden were associated with the compaction and subsidence and were most problematic in high-angle wells. An important factor in supporting the drilling teams in their decision-making process has been the development of wellbore stability models and the integration of drilling engineering and rock mechanics with subsurface technology. This paper briefly reviews the drilling history at Valhall prior to the ERD program initiated in the mid-90s, and more in detail the increasing problems in the late 90s in the ERD wells, where several very expensive wells did not make it to the reservoir target to produce oil. The paper reviews the work that supported the abandonment of the ERD program in favor of unmanned platforms in the North and South flank of the field, which resulted in the current drilling performance of the flank reservoir targets today being achieved with best-in-class drilling performance.
Gecko Wells: Bringing Sand to Surface, A Change in Well Design Philosophy
Authors: Ahmad Pg. Md. Fadilla Pg. Hj. , Ward Mike , Fisher Antony
Published: January 2008

Following an energetic, low unit development costs (UDC) workshop held by the Brunei Shell Petroleum (BSP) Darat asset team, with cross discipline, service company, and other low cost operator input, a fundamental change in well design was proposed. The Seria oilfield, managed by the BSP Darat asset group, is a billion barrel field that has been producing for over 60 years. As with most Brownfield sites, continued production faces a constant challenge to keep UDC economic. One of the major costs and well design requirements in this shallow oilfield is down hole sand control. It was proposed that if well design could be slimmed down, simplified, and sand produced to surface to be dealt with there, a significant reduction in well costs could be possible, even allowing for increased OPEX.

The paper will describe the change in well designs, the dynamics of a multi discipline team set up to manage this project, the drilling and completion of the wells, and the well start up process. Results from the wells will be presented along with future plans for the project, and …… why they were called Gecko wells!
Analysis of Spontaneous Capillary Imbibition for Improved Oil Recovery
Authors: Nurkamelia Nurkamelia , Arihara N.
Published: January 2008

Spontaneous water imbibition is an important recovery mechanism in water-flooding particularly in naturally fractured reservoirs. Scaling the core test data of spontaneous capillary imbibition with different injection fluids is crucial to properly design improved recovery methods and to predict their performances.

Spontaneous capillary imbibition experiments were performed under static co-current conditions, and recovery curves for brine and chemicals solutions were used for scaling the data in different cores and different interfacial tensions. Capillary Pressure and global mobility at water saturation behind imbibition front (Swf) were also extracted from the imbibition data of brine and chemical solutions. Relative permeability experiments were conducted at initial water saturation (Swi) and after imbibition.

Spontaneous imbibition of chemical solutions produced higher ultimate oil recoveries than brine imbibition. The scaling approach proposed by Li and Horne yielded satisfactory correlations for all the cases. Water relative permeability curves measured after brine imbibition showed close agreements with those measured at Swi, which suggests that we can save substantial time by sequentially conducting spontaneous imbibition and flooding tests. Finally, the global mobility was evaluated with those calculated at Swf from imbibition data and those calculated from the relative permeability data.
Effects of Oil-Water Mobility on Injectivity Impairment due to Suspended Particles
Authors: Altoé F. J. E. , Bedrikovetsky P. , Gomes A. C. A. , Siqueira A. G. , de Souza A. L. S.
Published: January 2008

Injectivity decline during sea/produced water injection is a wide spread phenomenon in offshore and onshore waterflood projects. It happens due to solid and liquid particles suspended in the injected water; their capture by the rock results in the hydraulic resistivity increase. The field injectivity decline history is used for characterisation of the formation damage system and consequent well behaviour prediction.

The injectivity index increases M times during the damage-free displacement of oil by water (M is the water-oil mobility ratio). It affects the well injectivity prediction during poor quality water injection and changes the results of injectivity decline curves interpretation.

We study the combined effect of the particle suspension injection and of the total oil-water mobility variation on well injectivity. An explicit formula for injectivity decline due to both effects was derived. The effect of the total oil-water mobility variation on injectivity is particularly significant for cases of heavy oil and relatively low formation damage.

The injectivity decline formula derived allows for determination of filtration and formation damage coefficients and filter cake permeability from the well injectivity history. Two examples of well data treatment for the deep-water offshore reservoir A (Campos Basin, Brazil) are presented.
A Semi-Analytical Method to Predict Well Deliverability in Gas-Condensate Reservoirs
Authors: Chowdhury Nitin , Sharma Ravi , Pope Gary A. , Sepehrnoori Kamy
Published: January 2008

A fine-grid simulation is needed to capture the build up of a condensate bank near wells operating below the dew point pressure. However, full-field simulations with a sufficiently fine grid will often not be feasible or will require very long computational times. A semi-analytical method has been developed that can be used to accurately predict the gas and condensate production rates from such wells and that has some advantages over the pseudo pressure approach. The semi- analytical method includes the effects of capillary number (high velocity) and non-Darcy flow. The new method has been implemented in a compositional reservoir simulator and verified with fine-grid compositional simulation results for both lean and rich gas-condensate fluids. Pressures, saturations, relative permeabilities, viscosities and densities calculated with the semi-analytical method are in excellent agreement with the results of fine-grid compositional simulations. Coarse grid simulations with grid block sizes on the order of 200 ft coupled with the semi-analytical method in grid blocks with wells yielded production rates as accurate as fine grid simulations with grid block sizes on the order of 2 ft. The method was tested for single-layer, multi-layer and multiwell gas-condensate reservoirs and found to give accurate results.
The Impact of Faults Representation on History Match and Future Generated Seismic Impedance Response in Reservoir Models—Case Study for Pierce Field, North Sea
Authors: Al-Busafi B. , Fisher Q. J. , Harris S. D. , Kendall M.
Published: January 2008

Transmissibility multipliers provide a simple way of accounting for the effects that faults have on fluid flow in production simulation models. Recent studies have shown that transmissibility multipliers can be quantified from parameters such as fault thickness and permeability (Knai and Knipe, 1998; Manzocchi et al., 1999). Generally, these latter parameters must be approximated using empirical relationships with some host rock properties such as V-shale or net-to-gross ratio as well as fault displacement magnitude (Manzocchi et al., 1999).

In this study, the effects of two different representations of faults on the history match and the predicted (simulated) seismic impedance are compared for the Pierce Field, North Sea. In the first case, fault transmissibilities were adjusted and the faults were extended in a trial and error manner to improve the match to fluid contacts and production history. In the second case, a step-by-step derivation of the fault transmissibilities in the Pierce Field was adopted based upon the integration of collected and upscaled properties of the deformed and undeformed reservoir as well as empirical relationships between fault offset and thickness. Historical production data were used to compare the effectiveness of the two methods. Furthermore, a synthetic seismic impedance response was generated from both simulation models, using a velocity model based on the Gassmann-Biot theory of elastic wave propagation in fluid saturated porous solid (Gassmann, 1951; Biot, 1956). This allows the assessment of different fault representations when trying to predict optimal times for further time-lapse seismic surveys. The results demonstrate the effectiveness of the derived transmissibilities model in generating a satisfactory history match in a relatively short time period. The generated seismic models show that, by acting as baffles/barriers to fluid flow, faults can play a major role in creating residual seismic features that can be observed on 4D seismic surverys. Incorporating realistic fault rock properties into the simulation model, which is used to create synthetic seismic, can therefore allow geophysicists and engineers to better plan the timing of 4D seismic surveys so that they have the greatest influence on field development decisions.
A Simulator For Produced Water Reinjection in Thermally Fractured Wells
Authors: Detienne J. L. , Ochi J. , Rivet P.
Published: January 2008

The objective of the analytical simulator presented here is to predict the opposite and complex effects induced by the injected produced water temperature and formation damage on thermally fractured wells. The deposition of solid particles and oil droplets in a fracture and its effect on the Injectivity Index evolution of an injector is then simulated. The principle is to inject cooled waters like sea water for example during a certain period of time to enable the well to develop a thermal fracture. When the fracture is well established, the re-injection of hot produced waters starts. The model takes into account the effect of this new water temperature on the viscous flow and on the fracture shrinkage and closure. In the same time oil droplets and solid particles contained in produced water cause the damage of the reservoir. This tends to open and propagate the fracture under bottom pressure increase. In the simulator, the internal formation damage and the external filter cake deposition in the fracture occur simultaneously. Two internal formation damage deposition models are taken into account. In a first model the internal damage is supposed to be linear and occurring from the fracture faces to the reservoir. In a second model, despite the growth of the fracture, the internal damage is supposed to be radial and occurring from the wall of the well to the reservoir. Also, two exeternal filter cake deposition models are considered: the filter cake deposits only at the fracture tip or on fracture faces. Theoretical field cases were considered in the simulations. The different internal formation damage and filter cake models were combined together to reproduce the injectivity index evolution observed on real fileds. The example presented are chosen to show that, contrarily to common thinkings, the II evolution can be dominated, in certain circumstances, by the internal damage rather then by the external filter cake deposition. With the present choice of data, the II evolution which matches better the commonly observed field reponses is obtained when the internal damage occurs in radial flow whatever the model deposition of the external filter cake is.
Advanced Drilling Using a Spiral Kelly
Authors: Girde P.
Published: January 2008

Conventional drilling techniques utilize a very important member in the drill string a ‘Kelly.’ This is about 45 ft. long and either a square or hexagonal cross-section. The main aim of this Kelly is to transmit torque to the drill string. This drilling technique results in low penetration rates, bulky drilling assemblies and high trip time. This paper adopts a new idea for the Kelly. This Kelly is spiral in its length and has a corresponding two piece Kelly bushing which is also spiral in nature. These spiral transmission systems are very commonly seen in many industries especially the heavy earth moving machinery and to a smaller extent in the automobile industry. They have a major advantage over all other transmission systems, such as much controlled penetration rates, because of the availability of maximum surface area. Grooves are highly efficient. In addition, slippage is totally eliminated, wear and tear is reduced to a minimum and high torque is easily transmitted. In this design, the kelly bushing is similar to that in a conventional system. Since the spiral kelly can take an enormous amount of load, jarring actions can be very easily done while the kelly is rotating. To implement the advantages of spiral Kelly I have designed a derrick having only 65ft height, Here we are using a two-piece bushing with balls placed inside the grooves which gives rise to less wear and tear as well by making the balls to circulate through the bypass line we can transmit only rotary motion so that in the case we encountered a hard formation the controlled penetration rate could be obtained The system is cost effective reducing rig time, as well it can be a best substitute for the normal drilling and workover derrick
Acid Number Measurements Revisited
Authors: Fan Tianguang , Buckley Jill S.
Published: January 2008

We propose an improved procedure for measuring acid numbers. Major changes include spiking crude oil samples and blank solutions with a known amount of stearic acid to force a clear titration endpoint, replacing potassium hydroxide with tetrabutyl ammonium hydroxide in the alcoholic titratant, and correctly accounting for changes in electrode response that occur upon exposure of the electrode to crude oil.
Effect of Cyclic Loading on the Microtensile Bond Strengths of Total-etch and Self-etch Adhesives
Authors: Toledano M. , Osorio R. , Albaladejo A. , Aguilera F. S. , Tay F. R. , Ferrari M.
Published: January 2008

Clinical Relevance

Resin-dentin bonds, which may have an influence on the long-term success of restorations, are prone to deterioration after cyclic loading. The tested one-step self-etching system (Etch&Prime 3.0) provided the least reliable dentin adhesion. After acid etching of dentin, alcohol/based adhesives performed better than those containing acetone as solvent.
Influence of Prefabricated Post Material on Restored Teeth: Fracture Strength and Stress Distribution
Authors: Barjau-Escribano A. , Sancho-Bru J. L. , Forner-Navarro L. , Rodríguez-Cervantes P. J. , Pérez-González A. , Sánchez-Marín F. T.
Published: January 2008

Clinical Relevance

When restoring teeth, a higher restoring success rate can be achieved by using posts with an elastic modulus similar to that of dentin and a core, with equal or higher strength, such as glass fiber posts. Moreover, the failure mode for these post systems will allow for further repair.
Effect of Saliva Contamination on the Microshear Bond Strength of One-step Self-etching Adhesive Systems to Dentin
Authors: Yoo H. M. , Oh T. S. , Pereira P. N. R.
Published: January 2008

Clinical Relevance

Saliva contamination significantly affects the bond strength of one-step self-etching adhesive systems to dentin; therefore, saliva contamination must be avoided when using these systems.
A 24-month Follow-up of Flowable Resin Composite as an Intermediate Layer in Non-carious Cervical Lesions
Authors: Reis A. , Loguercio A. D.
Published: January 2008

Clinical Relevance

After 24 months of evaluation, the use of Filtek Flow as a liner under Filtek Z250 restorations did not improve the clinical performance of Class V restorations.
Alternative Rubber Dam Isolation Technique for the Restoration of Class V Cervical Lesions
Authors: Owens B. M.
Published: January 2008

Clinical Relevance

This isolation technique is a time-saving dental rubber dam placement alternative for the restorative treatment of Class V cervical lesions.
Cervical Microleakage in MOD Restorations: In Vitro Comparison of Indirect and Direct Composite
Authors: Duquia R. C. S. , Osinaga P. W. R. , Demarco F. F. , Habekost L. V. , Conceição E. N.
Published: January 2008

Clinical Relevance

One of the advantages reported for indirect composite restorations is the reduction of polymerization shrinkage, which could produce better marginal sealing. Although sealing of cervical enamel margins was slightly better for the indirect systems used, no difference between indirect and direct restorations was found for cervical margins in cementum/dentin.
Influence of the Feldspathic Ceramic Thickness and Shade on the Microhardness of Dual Resin Cement
Authors: Soares C. J. , Silva N. R. , Fonseca R. B.
Published: January 2008

Clinical Relevance

Polymerization of dual resin cements is significantly more affected by thickness of feldspathic ceramic restorations than by shade.
Effect of New Generation Surface Sealants on the Marginal Permeability of Class V Resin Composite Restorations
Authors: Owens B. M. , Johnson W. W.
Published: January 2008

Clinical Relevance

Surface sealants, when applied to Class V resin composite restorations, can contribute to a significant reduction in microleakage, thus enhancing marginal integrity.
Effect of Dentin Conditioning Time on Nanoleakage
Authors: Duarte S. , Perdigão J. , Lopes M. M.
Published: January 2008

Clinical Relevance

Increasing dentin conditioning time did not affect nanoleakage for any of the dentin adhesives used in this study.
Bond Durability of Composite Luting Agents to Ceramic When Exposed to Long-term Thermocycling
Authors: Peumans M. , Hikita K. , De Munck J. , Van Landuyt K. , Poitevin A. , Lambrechts P. , Van Meerbeek B.
Published: January 2008

Clinical Relevance

Depending on the ceramic surface treatment and chemical composition of the luting cement, there is a varying degree of bonding effectiveness of resin composite cements to CAD-CAM ceramic after thermocycling.
Direct Resin Composite Restorations in Vital Versus Root-filled Posterior Teeth: A Controlled Comparative Long-term Follow-up
Authors: Adolphi G. , Zehnder M. , Bachmann L. M. , Göhring T. N.
Published: January 2008

Clinical Relevance

In endodontically-treated posterior teeth, minimal direct composite restorations had a tendency to fail more often than their counterparts in vital teeth.
Effect of Restoration Size on the Clinical Performance of Posterior “Packable” Resin Composites Over 18 Months
Authors: Brackett W. W. , Browning W. D. , Brackett M. G. , Callan R. S. , Blalock J. S.
Published: January 2008

Clinical Relevance

No association between restoration size and failure of the two posterior restorative systems was found over 18 months.
Reliability Modeling of Fault Tolerant Control Systems
Authors: LI Hongbin , Zhao Qing , Yang Zhenyu
Published: January 2008

Reliability Modeling of Fault Tolerant Control Systems

This paper proposes a novel approach to reliability evaluation for active Fault Tolerant Control Systems (FTCSs). By introducing a reliability index based on the control performance and hard deadline, a semi-Markov process model is proposed to describe system operation for reliability evaluation. The degraded performance of FTCSs in the presence of imperfect Fault Detection and Isolation (FDI) is reflected by semi-Markov states. The semi-Markov kernel, the key parameter of the process, is determined by four probabilistic parameters based on the Markovian model of FTCSs. Computed from the transition probabilities of the semi-Markov process, the reliability index incorporates control objectives, hard deadline, and the effects of imperfect FDI, a suitable quantitative measure of the overall performance.
Estimation of the Output Deviation Norm for Uncertain, Discrete-Time Nonlinear Systems in a State Dependent Form
Authors: Orłowski Przemysław
Published: January 2008

Estimation of the Output Deviation Norm for Uncertain, Discrete-Time Nonlinear Systems in a State Dependent Form

Numerical evaluation of the optimal nonlinear robust control requires estimating the impact of parameter uncertainties on the system output. The main goal of the paper is to propose a method for estimating the norm of an output trajectory deviation from the nominal trajectory for nonlinear uncertain, discrete-time systems. The measure of the deviation allows us to evaluate the robustness of any designed controller. The first part of the paper concerns uncertainty modelling for nonlinear systems given in the state space dependent form. The method for numerical estimation of the maximal norm of the output trajectory deviation with applications to robust control synthesis is proposed based on the introduced three-term additive uncertainty model. Theoretical deliberations are complemented with a numerical, water-tank system example.
Evolving Co-Adapted Subcomponents in Assembler Encoding
Authors: Praczyk Tomasz
Published: January 2008

Evolving Co-Adapted Subcomponents in Assembler Encoding

The paper presents a new Artificial Neural Network (ANN) encoding method called Assembler Encoding (AE). It assumes that the ANN is encoded in the form of a program (Assembler Encoding Program, AEP) of a linear organization and of a structure similar to the structure of a simple assembler program. The task of the AEP is to create a Connectivity Matrix (CM) which can be transformed into the ANN of any architecture. To create AEPs, and in consequence ANNs, genetic algorithms (GAs) are used. In addition to the outline of AE, the paper also presents a new AEP encoding method, i.e., the method used to represent the AEP in the form of a chromosome or a set of chromosomes. The proposed method assumes the evolution of individual components of AEPs, i.e., operations and data, in separate populations. To test the method, experiments in two areas were carried out, i.e., in optimization and in a predator-prey problem. In the first case, the task of AE was to create matrices which constituted a solution to the optimization problem. In the second case, AE was responsible for constructing neural controllers used to control artificial predators whose task was to capture a fast-moving prey.
Women Teachers in Canada, 1881–1901: Revisiting the ‘Feminization’ of an Occupation
Authors: Sager Eric W.
Published: January 2008

Using a mix of qualitative and quantitative approaches, this essay reconsiders the changing ratios of women to men in teaching in Canada in the late nineteenth century, and the relationship between macro-historical change and individual experience. The complete-coverage census micro-data for 1881 make it possible to explore possible associations between characteristics of 192 districts and the feminization of teaching in those districts. The hypothesis that an available pool of immigrant men delayed the feminization of teaching in parts of rural Ontario receives support at the national level. The economic structure of districts does not appear to be associated with the feminization of teaching. The feminization of teaching is associated with districts having relatively large proportions of French-Canadian Catholics and English Anglicans. The size of the school system, as measured by teachers per capita, is negatively associated with marital fertility. There is evidence that the status of women teachers had improved by the end of the century, although the reactions of individual teachers were ambiguous and conflicted. In Ontario the earnings of women teachers increased steadily in real terms. Women were being drawn into an occupation in which they were subordinates in a hierarchy of gender and income, but their movement into teaching was also a movement towards material independence, intellectual self-realization, and social respectability.
The Polish ‘Dionnes’: Gender, Ethnicity, and Immigrant Workers in Post–Second World War Canada
Authors: Sangster Joan
Published: January 2008

This article explores the themes of gender, ethnicity, and immigration in post–Second World War Canada, suggesting the ‘Fordist accord’ that emerged after the war was characterized by continuing inequalities in the labour force, particularly along the lines of ethnicity, ‘race’ and gender. By examining the controversy surrounding a small group of Polish displaced persons brought to Canada to work in the textile mill of Ludger Dionne, a Quebec member of Parliament, the article provides a window into contemporary debates about immigration and refugees. The Dionne ‘scandal’ was not only a concern for the public, the press, Parliament, and the labour movement, but also the Department of External Affairs, which had to repair damaged relations with Poland after the women were brought to Canada as displaced persons.
Cannabinoid receptor 1 gene (CNR1) and susceptibility to a quantitative phenotype for hebephrenic schizophrenia
Authors: Chavarría‐Siles Iván , Contreras‐Rojas Javier , Hare Elizabeth , Walss‐Bass Consuelo , Quezada Paulina , Dassori Albana , Contreras Salvador , Medina Rolando , Ramírez Mercedes , Salazar Rodolfo , Raventos Henriette , Escamilla Michael A.
Published: January 2008

Functional alterations of components of the endogenous cannabinoid system, in particular of the cannabinoid receptor 1 protein (CB1), are hypothetical contributors to many of the symptoms seen in schizophrenia. Variants within the cannabinoid receptor 1 gene (CNR1) have been shown to be directly associated with the hebephrenic form of schizophrenia in a Japanese population. This finding, however, has yet to be replicated. In the present study we sought to study the same (AAT)n‐repeat microsatellite of the CNR1 gene which showed association to hebephrenic schizophrenia in Japan, and to investigate whether this microsatellite showed association to a hebephrenic type of schizophrenia in a family‐based association study in a population of the Central Valley of Costa Rica. The Lifetime Dimensions of Psychosis Scale and a best estimate consensus process were utilized to identify subjects with schizophrenia who had an elevated lifetime dimensional score for negative and disorganized symptoms, which we used as a proxy for “hebephrenia.” Using the Family Based Association Test we found association of these hebephrenic subjects and the (AAT)n‐repeat marker of the CNR1 (multi‐allelic P = 0.0368). Our hypothesis that an association with the (AAT)n‐repeat marker of CNR1 would not be found with the more general type of schizophrenia was also confirmed. Schizophrenic subjects with prominent lifetime scores for disorganization and negative symptoms (dimension for hebephrenia) are associated with the CNR1 gene and present a type of symptomatology that resembles chronic cannabinoid‐induced psychosis. The current finding points to the possibility of different genetic and pathophysiologic mechanisms underlying different types of schizophrenia. © 2008 Wiley‐Liss, Inc.
Interactive effects of COMT Val108/158Met and MTHFR C677T on executive function in schizophrenia
Authors: Roffman Joshua L. , Weiss Anthony P. , Deckersbach Thilo , Freudenreich Oliver , Henderson David C. , Wong Donna H. , Halsted Charles H. , Goff Donald C.
Published: January 2008

Schizophrenia is characterized by heritable deficits in executive function. Two common, functional polymorphisms, catechol‐O‐methyltransferase (COMT) Val108/158Met and methylenetetrahydrofolate reductase (MTHFR) C677T, have separately been associated with executive function performance in schizophrenia. Given the closely related biochemistry of MTHFR and COMT, it is plausible that the T and Val alleles act synergistically to impair executive function. This investigation of 185 outpatients with schizophrenia examined the interactive effects of these two polymorphisms on Wisconsin Card Sorting Task (WCST) performance. Two WCST measures consistently associated with schizophrenia, perseverative errors and inability to generate categories, were contrasted among compound COMT‐MTHFR genotype groups. Individuals homozygous for the COMT Val allele who also carried at least one copy of the MTHFR T allele exhibited a significantly higher percentage of perseverative errors than patients in the other genotype groups. While the T allele also exerted a negative effect on category generation, COMT genotype did not contribute to category performance. It is plausible that cumulative effects of the MTHFR T and COMT Val alleles on intracellular methylation profiles and prefrontal dopamine transmission underlie their interactive effect on perseverative errors. © 2008 Wiley‐Liss, Inc.
No association between the protein tyrosine phosphatase, receptor‐type, Z Polypeptide 1 (PTPRZ1) gene and schizophrenia in the Japanese population
Authors: Ito Yoshihito , Yamada Shinnosuke , Takahashi Nagahide , Saito Shinichi , Yoshimi Akira , Inada Toshiya , Noda Yukihiro , Ozaki Norio
Published: January 2008

NRG1‐ERBB signaling influences the risk for schizophrenia pathology. A recent study has reported that MAGI1, MAGI2, and protein tyrosine phosphatase, receptor‐type, Z polypeptide 1 (PTPRZ1; located on 7q31.3) gene products regulate the NRG1‐ERBB4 signaling pathway, and PTPRZ1 is associated with schizophrenia in a Caucasian population. By applying a gene‐based association concept, we analyzed any association between PTPRZ1 tagging SNPs and schizophrenia in the Japanese population (576 schizophrenics and 768 controls). After linkage disequilibrium analysis, 29 single nucleotide polymorphisms (SNPs) were genotyped using a 5′‐exonuclease allelic discrimination assay. We found a significant association of one tagging SNP in a genotype‐wise analysis (P = 0.007); however, this might be resulted from type I error due to multiple testing (P = 0.17 after SNPSpD correction). No association was observed between schizophrenic patients and controls in either allelic, genotypic, or haplotypic analyses. Our results therefore suggest that PTPRZ1 is unlikely to be related to the development of schizophrenia in the Japanese population. © 2008 Wiley‐Liss, Inc.
Association of the serotonin transporter polymorphism and obsessive‐compulsive disorder: Systematic review
Authors: Bloch Michael H. , Landeros‐Weisenberger Angeli , Sen Srijan , Dombrowski Philip , Kelmendi Ben , Coric Vladimir , Pittenger Christopher , Leckman James F.
Published: January 2008

We investigated the association between the long (l) and short (s) alleles of the serotonin transporter polymorphism (5‐HTTLPR) in the promoter region of the SLC6A4 gene and obsessive‐compulsive disorder (OCD) using meta‐analysis to combine all published data from case–control and family based association studies (2,283 cases). In stratified meta‐analysis we investigated whether age of sample (child and adult), ethnicity (Caucasian and Asian) and study design (case–control and family‐based association studies) moderated any association. In the overall meta‐analysis we found no evidence of association between genetic variation at the 5‐HTTLPR locus and OCD. We did find significant heterogeneity between studies. In the stratified meta‐analyses, we demonstrated a significant association between the l‐allele and OCD in family‐based association studies and in studies involving children and Caucasians. Our meta‐analysis suggests the possibility that the l‐allele may be associated with OCD in specific OCD subgroups such as childhood‐onset OCD and in Caucasians. Further meta‐analyses based on individual patient data would be helpful in determining whether age of OCD onset, gender and the presence of comorbid illness (e.g., tics) moderates the relationship between 5‐HTTLPR and OCD. © 2008 Wiley‐Liss, Inc.
An experimental analysis of ingestion rates in an omnivorous species
Authors: Stammati M. , Sabbatini G. , Visalberghi E.
Published: January 2008

Food intake is difficult to estimate under natural conditions. We investigated ingestion rates of 14 different food types in 26 captive capuchin monkeys (Cebus apella). The procedure consisted in weighing a piece of food and using a two alternative choice tests to present food to the subject, alone in its cage. We recorded the food chosen and the time it took the subject to consume the food entirely. Consumption time was converted into ingestion rates (g/s) for each food type. Ingestion rates of food types significantly differed, and the difference was significantly higher among foods than among subjects. In particular, ingestion rates of the fruits were higher than those of human‐processed food. Interestingly, food preferences were significantly related to energy intake rate, i.e., to the amount of energy ingested per unit of time, but not with ingestion rates or energy content alone. The energy acquired by eating different types of food cannot be calculated on the basis of the time spent eating unless a correction factor for each given food (or similar ones) is applied. Future controlled studies should provide field researchers with such corrections factors, possibly using foods collected in the wild. Am. J. Primatol. 70:510–513, 2008. © 2008 Wiley‐Liss, Inc.
Begging for information: mother–offspring food sharing among wild Bornean orangutans
Authors: Jaeggi Adrian V. , van Noordwijk Maria A. , van Schaik Carel P.
Published: January 2008

Transfer of solid food from mothers or other adults to dependent offspring is commonly observed in various primate species and both nutritional and informational benefits have been proposed to explain the function of such food sharing. Predictions from these hypotheses are tested using observational data on wild orangutans (Pongo pygmaeus wurmbii) at Tuanan, Central Borneo, Indonesia. In 1,145 hr of focal observation and 458 recorded food interactions between four pairs of females with offspring it was found that virtually all transfers were initiated by the offspring and that younger infants solicited food more often and did so for a greater variety of items than older offspring. All offspring primarily solicited food that was difficult to process, i.e., inaccessible to them. Furthermore, the amount of food solicitation was negatively correlated with ecological competence. Hence food sharing seemed to be related to an offspring's skill level, as suggested by the informational hypothesis. In contrast, offspring did not solicit high‐quality items more than low‐quality items and food sharing did not peak around the age of weaning, as predicted by the nutritional hypothesis. Mothers were usually passively tolerant, allowing offspring to take food but hardly ever provisioned. Parent–offspring conflict concerning food sharing was only observed well after weaning. Thus, by taking food directly from the mother, young orangutans were able to obtain information about the affordances and nutritional value of food items that were otherwise out of their reach and could familiarize themselves with the mother's diet. In species such as orangutans or other apes, characterized by a broad diet that requires extractive foraging, informational food transfer may be vital for an immature to acquire complex feeding skills and adult diet. Am. J. Primatol. 70:533–541, 2008. © 2008 Wiley‐Liss, Inc.
When different persons have an identical author name. How frequent are homonyms?
Authors: Aksnes Dag W.
Published: January 2008

The phenomenon that different persons may have the same author name (homonymy) represents a major problem for publication analysis at individual levels and for retriving publications based on author names more generally. In such cases, all publications from the persons sharing the name will be collected in search results. This makes it difficult to provide a true picture of a researcher's publication output. The present study examines how frequent homonyms occur in a population of more than 30,000 individuals. The population represents the entire set of research personell in Norway. It is found that 14% of the persons share their author name with one or more other individuals. For the remaining 86% there is a one‐to‐one correspondence. Thus, for the large majority of persons, homonyms do not represent a problem. In the final part of the article, potential practical applications of these findings are given particular attention.
Higher order structure of (1,3)‐β‐D‐glucans and its influence on their biological activities and complexation abilities
Authors: Sletmoen Marit , Stokke Bjørn T.
Published: January 2008

(1,3)‐β‐D‐Glucans form a group of biologically active biopolymers that exist in different structural organizations depending on the environmental conditions. The biological effect of (1,3)‐β‐D‐glucans is a core issue stimulating large research efforts of the molecular properties and their consequences for action as biological response modifiers. The fascination for these molecules increased further following the finding of their ability to form complexes of defined geometry with a number of structures, ranging from linear architectures as polymers or carbon nanotubes, to globular structures as gold particles or dye molecules. The fascinating information concerning the relationship between sample treatment history and molecular organization has not yet reached out to all the contributors within the field, resulting in unnecessary apparent inconsistencies in the literature. In addition to environmental conditions, the sample history is known to influence on the precise structural organization of these molecules. The present knowledge related to the structure of native as well as denatured, renatured and annealed (1,3)‐β‐D‐glucans is reviewed. The influence of their structural organization on the biological activity and complexation abilities is discussed, and some factors hindering progress in the understanding of their biological effects or complexation abilities are pointed out. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 310–321, 2008.

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