bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual Application of Polyelectrolyte Complex Nanoparticles as Enzyme Breaker Carriers and Fluid Loss Additives for Fracturing Fluids
Authors: Bose Charles C , Alshatti AIR Bader , Swarts Levi , Gupta Aadish , Barati Reza
Published: September 2014

Guar-based fluids are commonly used as fracturing fluids to form a filter cake, propagate the fracture and carry proppants during a typical hydraulic fracturing job. High viscosity during injection and degradation afterwards are the characteristics of a high quality fracturing fluid that can maintain a highly conductive fracture during production. In order to achieve a conductive fracture, cross-linkers and breakers are added to the fluid. Filter cakes form on the faces of the fracture during injection causing a major pressure drop between the fracture and the reservoir during the production. Degradation of filter cakes formed on fracture faces has been accomplished using chemical breakers Enzymes and oxidizers are the two main classes of breakers. Enzyme breakers have many advantages over chemical oxidizers: they are cheap, are not consumed during their catalytic reaction with guar, react only with the polymer, are environmentally benign, easy to handle and do not damage wellhead equipment.

Different methods of injecting high concentration breakers are still not capable of degrading the residues left after the fracturing jobs. Permeability reduction of proppant pack due to gel residues, width loss caused by the unbroken gel on fracture face and length loss caused by incomplete degradation of filter cake near the tip of the fractures have been previously reported. It has been previously proven that polyethylenimine-dextran sulfate (PEI-DS) nanoparticles can delay the release of enzymes which reduce the viscosity of cross linked guar. This delayed release can be advantageous in order to inject higher concentrations of enzymes by encapsulating the enzyme inside nanoparticles. However, performance of these nanoparticles in reaction with high concentration filter cakes has not been studied yet.

The main objective of this work is to study the feasibility of using polyelectrolyte complex nanoparticles as enzyme breaker carriers and fluid loss additives to be used for hydraulic fracturing applications. Specifically, the fluid loss prevention and clean-up capabilities of the nanoparticle system for fractures propagated in tight formations are studied.

Static fluid loss tests showed a significant reduction, caused by PEC nanoparticles, in both fluid loss coefficients and fluid loss volumes of tight core plugs with permeability values within the 0.01-0.1 mD range.

Fracture conductivity tests, both fluid loss and clean-up, were conducted using HPG gel, HPG gel mixed with enzyme, and HPG gel mixed with enzyme-loaded nanoparticle systems and the results were compared with the baseline conductivity of the system. Significant improvement in the retained conductivity of the proppant pack was observed using the enzyme-loaded nanoparticle system.
Resolving In Situ Stress Regime, Hydraulic Fracture Geometry and Complexity by Comparing Acoustic Well Logging Data Acquired in Horizontal and Vertical Wells in the Montney Formation
Authors: Qiao Yong , Khalid Salman , Faurschou Ken , Knox Kim
Published: September 2014

This paper discusses the determination of in situ stress regime and its resulting impact on hydraulic fracture geometry through an analysis of two datasets that were acquired in a vertical well and a nearby horizontal well in a Canadian reservoir. The hydraulic fracture geometry monitored using microseismic was available for comparison.

When solving the poro-elastic horizontal strain model for closure stress, using analogous Hooke's Law for continuous media, one needs to resolve a stiffness tensor which requires determination of multi-dimensional shear. Measurements done in vertical wells using acoustic data are challenged by the limitation of not being able to directly record a horizontal shear. This limitation is typically overcome by modeling a horizontal shear using Stoneley mode firing. This well-developed technique works better when data is acquired using tools that allow simplified modeling of the tool wave, such as those tools that do not have slots cut in the housing to reduce direct signal coupling through the tool housing and mandrel. With the acquisition of simultaneous horizontal and vertical well data in the study, complementary information from the horizontal well provides a unique opportunity to physically confirm the validity of horizontal shear determined in the Vertical well, thereby providing further confidence in the modeling technique.

The analysis showed approximately 7% acoustic wave anisotropy for both compressional and shear wave in this part of the reservoir. It also indicated both vertical and horizontal transverse isotropic anisotropy presence. This enabled confirming a particular stress regime.

As fracures usually open up against minimum stress, once the three stresses σh, σv and σH are known, a comparison of the three stresses can predict the geometry of the induced fracture. In this case, the comparison of stresses revealed that the induced fractures should have been vertical. However that was not the case in reality. This suggested that additional factors could be impacting the outcome of the fracture. One possible factor is the presence of fine layering and lamination in the rock. When lamination is present induced fracture geometry is governed not only by stress but also by the frequency of lamination.

It was seen that the zone of interest was higly laminated and layered. As such this might have contributed to the observed fracture complexity
Tight Cardium Multi-Stage Fractured Horizontal Oil Well Performance Study Focusing on the Effectiveness of Various Fracture Fluid Systems
Authors: Reynolds Murray , Gallup Michael , Moscoso Krefthelle , Buendia Juliana
Published: September 2014

In recent years, the tight Cardium sandstones of west central Alberta have seen significant new development with the application of multi-stage fractured horizontal wells. This case study reviews the completion costs, economics and production performance of 148 horizontal oil wells completed in the Pembina Field halo areas (west and east), central Pembina, Willesden Green and Garrington Fields.

Production analysis was performed on all wells using the Duong decline curve analysis technique. This technique has been successfully used on tight multi-stage fractured wells in other areas, and has proven successful at predicting long-term well performance and recoveries. Wells were chosen for comparison that were in the same geological and pressure regions, had a minimum of 2 years of production information, and were stimulated with various fracture fluid systems.

In one of the analyzed areas, a definite trend was identified; it was found that wells drilled in a certain orientation performed better than wells drilled with other orientations.

Completions and hydraulic fracturing costs were gathered from public sources in order to understand the cost differences between areas and types of fracture fluid systems. Using decline curves and cost information, full cycle economics were run on the ‘average’ well for each area in order to determine the Net Present Value (NPV) of each area.

This case study shows there is value in optimizing fracture designs through look-back studies, and there is a need to focus on more effective fracture treatment designs in unconventional oil development.
Level Set Method for Tracking the Penetration Front of a Fracturing Fluid in Heterogeneous Reservoirs
Authors: Chen Cheng , Hampton Jesse , Martysevich Vladimir
Published: September 2014

Shale permeability is low enough to require unconventional stimulation treatment, such as hydraulic fracturing. Hydraulic fracturing is now widely used to achieve a larger stimulated reservoir volume by connecting intrakerogen pores, which are otherwise isolated from one another. It is important to monitor and predict the migration of fracturing fluid. The authors studied fracturing fluid injection in a granite rock in the laboratory and observed a sharp penetration front, implying the motion of the penetration front is advection-dominated. Based on this, they developed a numerical model using the level set method to track the penetration front of fracturing fluid. In the model, auto-correlated Gaussian random fields are generated to represent heterogeneous permeability distributions. Reservoir heterogeneity is measured using the coefficient of variation, which is defined as the ratio between standard deviation of permeability and mean permeability. The correlation length in the horizontal direction is much larger than in the vertical direction, implying a horizontal layered structure. The authors investigated the effect of heterogeneity on penetration front motion. Using the same statistical parameters, numerous realizations of the permeability field are generated. A finite difference reservoir simulator equipped with the weighted Jacobi iteration method was then used to solve for the Darcy flow fields, and the level set simulation was repeated to study the collective behavior of the system. In all simulations, the authors observed linear relationships between time and the first- and second-order spatial moments of the penetration fronts. The time derivatives of the first- and second-order spatial moments were the velocity and dispersion coefficient, respectively. With increasing reservoir heterogeneity, velocity decreased linearly, while the dispersion coefficient increased linearly. These observations imply there is a strong coupling between penetration front motion and reservoir heterogeneity. Therefore, to accurately predict the movement of fracturing fluids, it is necessary to effectively characterize heterogeneity of the host formation. This study is the first to systematically investigate the correlation between fracturing fluid penetration and reservoir heterogeneity using the level set method. It has important applications with respect to optimization of fracturing fluid injection.
Geomechanical Characterization of an Unconventional Reservoir with Microseismic Fracture Monitoring Data and Unconventional Fracture Modeling
Authors: Li Qiuguo , Zhmodik Alexey , Boskovic Drazenko
Published: September 2014

Hydraulic fracturing is often the most effective option to stimulate production in unconventional reservoirs to economic levels. Results of stimulation can be mixed unless the hydraulic fracture design correctly interprets the geological and geomechanical setting of the field. In fields with naturally fractured reservoirs, the interpretation is particularly critical because natural fractures strongly influence the final stimulated rock volume. An accurate description of the natural fracture network and the geomechanical properties and stresses of the rock provide the information to optimize stimulation treatment in naturally fractured unconventional reservoirs. However, the uncertainty in some of this information can jeopardize the value of the modeling and the success of the stimulation. One of the key geomechanical parameters, which are often poorly constrained, is the maximum horizontal stress magnitude. Microseismic data are able to map the stimulated rock volume during hydraulic fracturing operations. These data can be used to verify the accuracy of the fracturing treatment modeling.

Here, we present a case study characterizing geomechanical parameters of an unconventional reservoir using a novel technique that includes calibrated mechanical earth models. The technique reduces uncertainty in the geological and geomechanical parameters used to design hydraulic fracture operations, improving the prediction of the final stimulated rock volume.
Downhole Choke Applications and Performance Impact: A Tupper Field Montney Evaluation
Authors: White Aaron J. , Lavery P. E. , Rock L.
Published: September 2014

Murphy Montney has been implementing downhole chokes in a variety of successful applications that have resulted in both significantly improved well performance and facility equipment/chemical cost savings. The specific applications piloted have included:

Rate Restriction Mitigating Sand Plugging Surface Hydrate Elimination Liquid Unloading

The observed reservoir performance improvement and mitigation of downhole sand plugging is the result of minimizing the net pressure condition created within the induced fracture network. Restricted well drawdown minimizes the physical loss of the induced stimulation, loss which leads to the downhole plugging situation. In addition, Montney pressure dependent reservoir responses have demonstrated stimulated reservoir volume (SRV) flow capacity and fracture conductivity improvement/maintenance under higher flowing sandface pressure conditions, significantly enhancing the minimum-contacted-gas-in-place (CGIPmin). A conceptual reservoir model whereby early pressure maintenance and long-term pressure management is required to maximize the EUR and long-term production has been developed.

Downhole chokes are being used in lieu of surface line heaters and methanol injection in the mitigation of surface hydrate formation. By moving the point of pressure and temperature reduction downhole, the Joule-Thompson cooling response across the choke is geothermally regulated.

Success has also been observed in liquid unloading applications. Downhole choking can create a choked flow rate Venturi effect, which by definition is based upon a critical upstream to downstream pressure ratio, a function of the gas specific heat relationship. Choked flow accelerates gas to a sonic velocity across the flow restriction, imparting a sufficient velocity head upon an upstream fluid level to carry a water droplet to surface. The acceleration of fluid droplets across the downhole choke is equivalent to an infinite lowering of the liquid loading rate, limited only by the maintenance of the choked flow condition created across the downhole choke.

The downhole choke permits for a controlled and self-regulated drawdown, creating both improved reservoir performance and well operations. Mitigating surface hydrate formation and frac sand flowback has resulted in significant cost savings. A novel application specific to over-pressured reservoirs is the use of downhole chokes in liquid unloading applications, maintaining high flowing sandface pressure conditions while unloading liquid.
Shale Bedding Impact on Wellbore Stability and Drilling Optimization
Authors: Gao Jordan , Odunlami Tosin , Osayande Nadine
Published: September 2014

It is well known that shale can be a problematic lithology that is capable of creating issues such as tight hole and pipe stuck during a drilling operation. Shale bedding is recognized as one of the key factors that directly contributes to drilling problems. This paper focuses on shale bedding's impact on wellbore stability, which is investigated with the comparison of wellbore stability results of the shale formation with shale bedding and without shale bedding. The geomechanical simulation results show that: (1) the characteristics of wellbore stability polar plot for all well trajectories can be dramatically changed by shale bedding; (2) both well azimuth and well inclination have significant impact on wellbore stability; (3) stress dominated and shale bedding dominated wellbore breakouts can be evaluated; (4) formation strength control and shale bedding strength control wellbore stability are indentified. Based on those simulated wellbore stability characteristics, optimizations for well azimuth, well inclination, well trajectory, and mud weights can be designed for drilling operation to mitigate the potential drilling hazards.
Experimental Investigation of Proppant Diagenesis
Authors: Ghosh Sayantan , Rai Chandra S , Sondergeld Carl H , Larese Richard E
Published: September 2014

Comparative role of mechanisms such as proppant crushing, embedment, diagenesis and fines migration is not well understood regarding hydraulic fracture conductivity. In this study, we have measured the long term permeability changed in the proppant pack under downhole conditions of temperature, confining pressure, pore pressure and fluid salinity. Major part of this study investigates proppant diagenesis and its role in hydraulic fracture conductivity reduction. Diagenesis is defined as any change in the proppant/shale material after proppant placement. Proppant indentation on the shale surface was also studied along with changes in chemical composition of the exit brine.

Diverse types of secondary growths were observed both on the proppant as well as the shale surface. Most of the secondary growth using the quartz proppant and low flow rate was observed near the shale edges where the brine velocity was low. Ceramic proppant showed the most secondary growth, while resin coated proppant showed no growth. The pH of the exit fluid of several tests show dependence on carbonate content of shale. Significant permeability change that was observed with high flow rate tests was not observed at low flow rates. For quartz proppant, considerable amount of proppant breakage and indentation was observed. Fines generation causing permeability reduction was observed in tests conducted with quartz and ceramic proppants but not resin coated proppants. Indentation depth showed dependence on proppant type and distribution.

Introduction

Hydraulic fracturing is conducted to create a pathway for the hydrocarbons to flow into the wellbore from the reservoir. Fracturing fluid under very high pressure is pumped along with proppants during this procedure. While the high hydraulic pressure helps in fracture initiation and propagation, the proppant helps in keeping the fracture open after pressure removal for easy flow of hydrocarbons. Economic production from shales is attributed mainly to hydraulic fracturing. Shales exhibit very low permeability, usually in the range of 10-1000 nanodarcies. At such low permeability, the use of multistage hydraulic fracturing is inevitable. Proppants are pumped during the hydraulic fracturing process. Their interaction with the shale matrix and the surrounding liquid is important to understand because this governs the long term permeability of the fracture. This paper discusses the results of long term studies conducted at simulated reservoir conditions to study the proppant behavior and associated fracture permeability.
The Wind-Induced Vibration Response for Tower Crane Based on Virtual
Excitation Method
Authors: Jiang Hongqi , Li Shuncai
Published: September 2014

The dynamics of Tower Crane is complicated by wind excitation which complicates the wind-induced
vibration response analysis. The random wind-induced response analysis of tower crane is presented based on finite
element method and virtual excitation method. The pulsating wind loads change into multiple-point correlation stationary
excitation. This paper uses Davenport’s wind speed spectrum which does not change with height, and considers multiplepoint
correlation of wind-induction. The tower crane was employed as a numerical example; the response spectra and
Mean Square Root (RMS) of the tower crane were obtained by wind-induced vibration. The results indicate that the
vibration of the tower crane showed a greater response in low frequency with the One-third Octave acceleration RMS
being lower. Finally, the influences of the wind-induced vibration on comfort were analyzed.
Study on the Interaction Mechanism of Packer Slips and Thick Wall
Casing
Authors: Dou Yihua , Pan Huanhuan , Tong Shaokai , Cao Yinping , Gao Wenxiang
Published: September 2014

The slips should go into casing for certain depth to set the packer when well testing, but the casing may be
damaged seriously if the setting force is too large. To make known the interaction mechanism of packer and casing, and
then provide basis for the choice of hanging load of casing and shape optimization of slips, the maximum hoop stress of
casing in the inner wall was deduced by the thick wall theory and the limited setting force was obtained by the strength
theory. The changes of the limited setting force of casing with the variable length of packer and the face angle of slip teeth
were discussed taking the general packer and casing as example. It was found that the limited setting force of casing
increased with the length of slip when the packer and casing kept the same. The shorter the slip, the faster the force grows.
Also, the limited setting force of casing increased non-linearly with the face angle of slip teeth. The smaller the angle, the
faster the force grows.
Analysis of Limit Setting Force of Casing Inside Slips Based on Cylindrical
Shell Theory
Authors: Cao Yinping , Tong Shaokai , Dou Yihua
Published: September 2014

Casing will be damaged in a well because of the setting force, and may even be broken when the force is too
large. To clearly demonstrate the interaction of the mechanism of packer and casing, a mechanical model of casing as
thin-wall cylinder was established with the consideration of the axial force and additional bending moment induced by the
bending of casing near the slips of packer. And, the equation of limit setting force on the casing exerted by slips was
deduced by bending moment theory of cylindrical shell. The relationships of the limit setting force of N80, P110, TP140
casing and thickness were analyzed. It was found that the bending stress and the hoop stress were the biggest near the
bottom of the slips, and that position was the dangerous section. The limit setting force of casing exerted by slips
increased with the thickness of casing, when the packer and the outer diameter of casing remained the same. And the limit
setting force was higher in high grade casing. The limit setting force calculated in this paper was decreased by 5 % to 14
% than by thick-wall theory, and it is deduced to be safer. The method proposed in the paper can be used to evaluate the
limit setting force and provide the basis for the choice of hanging load.
Research on Nonlinear Dynamic Characteristics and Stability of
Aerodynamic Bearings
Authors: Chen-Hui Jia , Cai-Feng Du , Ming Qiu
Published: September 2014

In order to research the conical spiral groove aerodynamic bearings, the lubrication mathematical model of the
bearings was established. The Reynolds equation of the laminar flow condition is used to calculate the partial differential
equation of the perturbation pressure with the local finite difference method. Through calculating the stiffness and
damping coefficient, the influence of the speed of law and eccentricity ratio on the dynamic characteristic coefficients has
been gained. The mathematical model for the stability of the bearing-rotor system is established to study the influence law
of speed influence of the law of speed and eccentricity ratio on the stability. The results show that the influence of the
bearing's speed and eccentricity on the dynamic characteristics is significant. A reasonable choice of the bearing's speed
and eccentricity contributes to improve the dynamic characteristics and the stability of the bearing-rotor system.
Effect of Rare Earth Upon As-Cast Microstructure and High Temperature Performance of ZA40 Alloy
Authors: Ji Jiaming , Meng Guocui , Lu Yuanyong , Shao Honghong , Gu Dongqing
Published: September 2014

In testing comparison, this study is made on the modification effect of 0.05 wt.% La-rich rare earth (RE) upon
as-cast microstructure, mechanical properties of materials at high temperatures (100, 150, 200°C) and wear resistance
under different temperatures (100and 200°C) of ZA40 alloy containing Si. The addition of RE shows that it can not only
effectively refine Al-rich and Cu-rich phase, but also reduce the amount of needle-like eutectic silicon, and then make the
size of massive primary silicon phase smaller. Thus, there are the improvement of strength, ductility and wear resistance
of materials at high temperature. The analyses are also conducted on the mechanism of underlying RE elements.
Numerical Solution of High-Dimensional Nonlinear Rotor-Bearing
Dynamic System with Precise Integration
Authors: Shi Guangtian
Published: September 2014

Through an example of rotor system which has multi-degree of freedom mounted on the nonlinear fluid film
bearings, this paper analyzes the precise integration algorithm, a new numerical solution for high–dimensional nonlinear
dynamics system. The precise integration method has advantages of long step, high precision and absolute stability for
solving nonlinear dynamics equations. To make good use of the method, firstly, the precise integral iterative formula is
given and then the mechanism of controlling high precision and efficiency is discussed. The evolution of precise
integration method is an algorithm with explicit, simple form, self-start, and fast to solve nonlinear dynamics equations.
High power of athwart of Hamiltonian matrix is not needed, so it is convenient in this case. The stability of period
response of nonlinear rotor-bearing system is analyzed by employing the precise integration method. The bifurcation rules
of the period response of the elastic rotor system with multi-degree of freedom are obtained and the chaos of the system is
determined according to the fractal dimension of Poincare mapping of phase space at a certain speed.
An Improved Algorithm of Extracting Fault Diagnosis Rules Based on Rough Sets
Authors: Li Juanli , Yang Zhaojian
Published: September 2014

Rough set is a new data analysis theory. It is often used to deal with fuzzy and uncertain problems. Attribution
reduction is the key step in obtaining the knowledge by utilizing rough set. An improved heuristic reduction algorithm of
attribute significance is proposed in the study based on analyzing the classic knowledge acquisition method of rough set
theory. The algorithm corrects the discernibility matrix and redefines the calculation method of attribute importance. Then
it fuses the both, gets the core by using the revised method of discernibility matrix and calculates the attribute importance
by using the weighted method and then the algorithm is applied to extract the rules of the hoist fault diagnosis. Verified by
the experiment, using the algorithm, it can excavate high reliability diagnosis rules from existing history diagnosis
knowledge and expert knowledge. This method can provide reasonable basis for fault diagnosis.
Grazing and Hopf Bifurcations of a Periodic Forced System with Soft
Impacts
Authors: Xifeng Zhu , Quanfu Gao
Published: September 2014

Based on the research of a periodic forced system with soft impacts, the piecewise properties of the soft-impacts
system, such as asymmetric motion and singularity, were analyzed by using the Poincaré map and Runge-Kutta
numerical simulation method. The routes from periodic motions to chaos, via Hopf bifurcation and grazing bifurcation,
were investigated thoroughly. In the case of large constraint stiffness, the Hopf bifurcation is observed in the periodic
forced system with soft impacts. The clearances of the system are the main reasons for influencing the chaotic motion. For
small clearances, the grazing bifurcations bring about asymmetric motion and singularity. The steady 1-1-1 period orbits
will exist within a wideband frequency range when appropriate system parameters are chosen.
Experimental Study on Vibration Transmissibility Properties of Honeycomb Paperboard
Authors: Quanfu Gao , Dapeng Zhu , Xingxiao Cao
Published: September 2014

The vibration transmissibility properties of a honeycomb paperboard are investigated by experiments. The
analysis of the steady-state response of mass loaded honeycomb paperboard system to harmonic base excitation is
presented in this paper. An experiment system is formulated and the vibration transmissibility data are obtained under
different base excitation amplitude conditions. According to the transmissibility experiments data, we can assume that
both the stiffness and damping properties are nonlinear. The hysteresis loops of the honeycomb paperboard-mass system
are experimentally obtained, and are used to investigate the stiffness and damping properties of the system. The
honeycomb paperboard’s uni-directional vibration transmissibility behavior is modeled by using nonlinear stiffness, the
combination of velocity proportional damping and quadratic type nonlinear damping components. The parameters in the
model are identified by use of one-term harmonic balance method and the parameters under different load condition are
presented. The model and the parameters in this paper can be used to simulate the transmissibility-frequency curves
accurately. The model can be used for understanding the vibration transmissibility behaviors of the honeycomb
paperboard, and the simulated transmissibility-frequency curves can be used for the packaging design.
The Research and Development of the Amphibious Disaster-Resistant
Submersible Pump with Dual Pump and Dual Motor
Authors: Yicheng Feng
Published: September 2014

This thesis introduces a kind of horizontal wet electric submersible pump unit with both submersible and nonsubmersible
operational models which can be installed permanently. Then, it analyses the structural features, operating
principles, main component performance and rotor system. A series of technical advantages show that this kind of
submersible pump has a bright application prospect in conventional drainage and disaster-resistant emergency drainage of
deep mines.
Co-Simulation and Experimental Research of Wedge Broken-Belt
Catching Device
Authors: Li Jun-Xia , Kou Zi-Ming , Du Jian-Wei
Published: September 2014

The paper conducted a research on a broken-belt catching machine based on full face catching. The device is a
mechanical electrical hydraulic integration design, driven by hydraulic pressure to achieve catching work. This paper
introduces its principle and basic composition, using ADMAS and AMESim simulation software to verify the rationality
of the design. Prototype was produced for the experiment in the laboratory. The results show that the catching device can
safely complete the work and the arrest meets the design requirements, without significant impact to performance.
Comparative effectiveness of injectable paliperidone palmitate versus oral atypical antipsychotics: early postmarketing evidence
Authors: Morrato Elaine H , Parks Joe , Campagna Elizabeth J , Muser Erik , Thomas Deborah SK , Fang Hai , Doshi Dilesh
Published: September 2014

Aim:
To provide comparative effectiveness evidence for long-acting injectable paliperidone palmitate versus oral atypical antipsychotics.
Patients & methods:
We performed a retrospective, observational cohort study using patient claims data from Missouri Medicaid to compare the likelihood of emergency department (ED) visits and hospitalizations in the year following drug initiation using multivariable logistic regression.
Results:
Adjusted odds ratios (AOR) for ED visits (AOR: 0.63; 95% CI: 0.47–0.85) and hospitalizations (AOR: 0.85; 95% CI: 0.64–1.13) were lower in paliperidone palmitate patients, although hospitalizations did not achieve statistical significance. Sensitivity analyses examining mental health-related outcomes and using different analytic strategies for patient selection bias showed directionally similar beneficial effects but were not statistically significant.
Conclusion:
Early evidence for paliperidone palmitate under real-world conditions is encouraging. However, caution should be taken until additional research substantiates the findings with greater certainty.
An Examination of How Entry-Level Staff Auditors Respond to Tone at the Top vis-à-vis Tone at the Bottom
Authors: Pickerd Jeffrey S. , Summers Scott L. , Wood David A.
Published: September 2014

Prior academic and practitioner literature argues that the ethical tone at the top of an organization is a key factor in establishing an effective internal control environment. Drawing on self-concept maintenance theory and in-group bias theory, this study predicts that entry-level staff auditors will disregard a company's ethical standards unless they observe a strong ethical tone from both their partner (tone at the top) and their supervising senior (tone at the bottom). Also, this study predicts that staff auditors will be more influenced by the tone of their supervising senior than the partner when these two individuals provide conflicting tones. In a 2 × 2 experiment that manipulates the tone set by a staff auditor's supervising senior and engagement partner, this study provides evidence consistent with predictions. Further analyses suggest that participants make less ethical decisions because they are less likely to view the situation as an ethical dilemma when either the senior or partner exhibits low tone. The results of this study emphasize that tone at the top is not, by itself, sufficient to produce ethical decision making; organizations must strive to foster a strong ethical tone throughout the entire organization, especially at lower levels of the organization.
Witnessing Your Own Cognitive Bias: A Compendium of Classroom Exercises
Authors: Fay Rebecca G. , Montague Norma R.
Published: September 2014

Accounting and auditing professors continually stress the importance of effective judgment and decision making (JDM), yet few accounting programs or textbooks discuss the biases that may impact an individual's ability to exercise high-quality professional judgment. In recent years, KPMG (Ranzilla, Chevalier, Herrmann, Glover, and Prawitt 2011) and the Committee of Sponsoring Organizations of the Treadway Commission (KPMG, Glover, and Prawitt 2012) addressed this gap at the corporate level by publishing guidance for accounting professionals and board members on how to identify and mitigate common judgment biases, yet there remain few resources designed for accounting students. This collection of exercises enables instructors to introduce the topic of effective JDM in the classroom. It provides students with the opportunity to identify bias in their own judgments by highlighting five frequently occurring biases that adversely impact business judgments (i.e., availability, anchoring, overconfidence, confirmation, and rush to solve). This compendium gathers exercises from psychology literature that may be used to pique student interest and encourage discussion of how each bias impacts judgments made by accounting professionals and how individuals may reduce their impact.
How to Discuss a Paper: Developing and Showcasing Your Scholarly Skills
Authors: Cook Kirsten A. , Hart Matthew , Kinney Michael R. , Oler Derek K.
Published: September 2014

We offer this paper as a primer for accounting doctoral students and new faculty on how to discuss a paper. We believe that this topic can serve to “jump start” the engagement of students and junior faculty in developing and delivering quality discussions. We begin by emphasizing the importance and benefits of being a good discussant to both the profession and the discussant. We then outline the discussion process and provide detailed suggestions on points to consider in each phase of this process: (1) volunteering to discuss, (2) receiving the discussion assignment, (3) preparing the discussion, (4) presenting the discussion, and (5) following up with the authors after the discussion. Next, we examine data that highlight the need for additional discussant volunteers at conferences. Finally, we present possible innovations to foster high-quality discussions. This paper formalizes the ideal process typically learned through years of mentoring and conference experience.
Business Process and Value Delivery Modeling Using Possession, Ownership, and Availability (POA) in Enterprises and Business Networks
Authors: Scheller Christian Vibe , Hruby Pavel
Published: September 2014

This paper describes a metamodel and notation for value delivery business process modeling, describing value delivery as flows of possession, ownership, and availability of economic resources between economic agents, value creation, and consumption, and a transfer of resources between agents' repositories. The motivation of the solution was to refine the REA ontology by replacing the generic concept of change in an economic resource with more specific concepts of change in ownership, change in possession, and change in the availability of an economic resource. The concepts of possession and ownership map directly to the same concepts in property law. The expressive power of the POA model covers traditional accounting, the REA ontology, and value networks. A POA model has the graphical notation and semantic precision that is required for model-driven design of ERP applications, supply chain applications, and enterprise information systems.
Measuring the Cost of Individual Disruptions in Multistage Manufacturing Systems
Authors: Bai Ge , Kajiwara Takehisa , Liu Jianbo
Published: September 2014

A Multistage Manufacturing System (MMS), in which interconnected workstations fabricate products, plays an important role in modern manufacturing facilities. An MMS is subject to random disruptions originating at individual workstations. Understanding the cost of individual disruptions is critical for executional cost management at the plant-floor level. However, the interdependence of the workstations makes it challenging to measure the cost of individual disruptions. One disruption might stop another workstation and cause a system shutdown, while inventory buffers might compensate for another disruption, which will then have no impact on system output. We propose a four-step procedure to measure the cost of individual disruptions and conduct a simulation study using field data from an automobile assembly line. The results show that cost information generated by the proposed procedure is useful for both “cost bottleneck” identification and performance evaluation, and thus can facilitate executional cost management at the plant-floor level.
Adipocyte ATP-Binding Cassette G1 Promotes Triglyceride Storage, Fat Mass Growth, and Human Obesity
Authors: Frisdal Eric , Le Lay Soazig , Hooton Henri , Poupel Lucie , Olivier Maryline , Alili Rohia , Plengpanich Wanee , Villard Elise F. , Gilibert Sophie , Lhomme Marie , Superville Alexandre , Miftah-Alkhair Lobna , Chapman M. John , Dallinga-Thie Geesje M. , Venteclef Nicolas , Poitou Christine , Tordjman Joan , Lesnik Philippe , Kontush Anatol , Huby Thierry , Dugail Isabelle , Clement Karine , Guerin Maryse , Le Goff Wilfried
Published: September 2014

The role of the ATP-binding cassette G1 (ABCG1) transporter in human pathophysiology is still largely unknown. Indeed, beyond its role in mediating free cholesterol efflux to HDL, the ABCG1 transporter equally promotes lipid accumulation in a triglyceride (TG)-rich environment through regulation of the bioavailability of lipoprotein lipase (LPL). Because both ABCG1 and LPL are expressed in adipose tissue, we hypothesized that ABCG1 is implicated in adipocyte TG storage and therefore could be a major actor in adipose tissue fat accumulation. Silencing of Abcg1 expression by RNA interference in 3T3-L1 preadipocytes compromised LPL-dependent TG accumulation during the initial phase of differentiation. Generation of stable Abcg1 knockdown 3T3-L1 adipocytes revealed that Abcg1 deficiency reduces TG storage and diminishes lipid droplet size through inhibition of Pparγ expression. Strikingly, local inhibition of adipocyte Abcg1 in adipose tissue from mice fed a high-fat diet led to a rapid decrease of adiposity and weight gain. Analysis of two frequent ABCG1 single nucleotide polymorphisms (rs1893590 [A/C] and rs1378577 [T/G]) in morbidly obese individuals indicated that elevated ABCG1 expression in adipose tissue was associated with increased PPARγ expression and adiposity concomitant to increased fat mass and BMI (haplotype AT>GC). The critical role of ABCG1 in obesity was further confirmed in independent populations of severe obese and diabetic obese individuals. This study identifies for the first time a major role of adipocyte ABCG1 in adiposity and fat mass growth and suggests that adipose ABCG1 might represent a potential therapeutic target in obesity.
Intranasal Insulin Enhanced Resting-State Functional Connectivity of Hippocampal Regions in Type 2 Diabetes
Authors: Zhang Hui , Hao Ying , Manor Bradley , Novak Peter , Milberg William , Zhang Jue , Fang Jing , Novak Vera
Published: September 2014

Type 2 diabetes mellitus (T2DM) alters brain function and manifests as brain atrophy. Intranasal insulin has emerged as a promising intervention for treatment of cognitive impairment. We evaluated the acute effects of intranasal insulin on resting-state brain functional connectivity in older adults with T2DM. This proof-of-concept, randomized, double-blind, placebo-controlled study evaluated the effects of a single 40 IU dose of insulin or saline in 14 diabetic and 14 control subjects. Resting-state functional connectivity between the hippocampal region and default mode network (DMN) was quantified using functional MRI (fMRI) at 3Tesla. Following insulin administration, diabetic patients demonstrated increased resting-state connectivity between the hippocampal regions and the medial frontal cortex (MFC) as compared with placebo (cluster size: right, P = 0.03) and other DMN regions. On placebo, the diabetes group had lower connectivity between the hippocampal region and the MFC as compared with control subjects (cluster size: right, P = 0.02), but on insulin, MFC connectivity was similar to control subjects. Resting-state connectivity correlated with cognitive performance. A single dose of intranasal insulin increases resting-state functional connectivity between the hippocampal regions and multiple DMN regions in older adults with T2DM. Intranasal insulin administration may modify functional connectivity among brain regions regulating memory and complex cognitive behaviors.
BMI and Coronary Heart Disease Risk Among Low-Income and Underinsured Diabetic Patients
Authors: Li Nan , Katzmarzyk Peter T. , Horswell Ronald , Zhang Yonggang , Li Weiqin , Zhao Wenhui , Wang Yujie , Johnson Jolene , Hu Gang
Published: September 2014

OBJECTIVE

The association between obesity and coronary heart disease (CHD) risk remains debatable, and no studies have assessed this association among diabetic patients. The aim of our study was to investigate the association between BMI and CHD risk among patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The sample included 30,434 diabetic patients (10,955 men and 19,479 women) 30–95 years of age without a history of CHD or stroke in the Louisiana State University Hospital-Based Longitudinal Study.

RESULTS

During a mean follow-up period of 7.3 years, 7,414 subjects developed CHD. The multivariable-adjusted hazard ratios for CHD across levels of BMI at baseline (18.5–24.9, 25–29.9, 30–34.9, 35–39.9, and ≥40 kg/m2) were 1.00, 1.14 (95% CI 1.00–1.29), 1.27 (1.12–1.45), 1.54 (1.34–1.78), and 1.42 (1.23–1.64) (Ptrend < 0.001) in men and 1.00, 0.95 (0.85–1.07), 0.95 (0.84–1.06), 1.06 (0.94–1.20), and 1.09 (1.00–1.22) (Ptrend < 0.001) in women, respectively. When we used an updated mean or last visit value of BMI, the positive association between BMI and CHD risk did not change in men. However, the positive association of BMI with CHD changed to a U-shaped association in women when we used the last visit value of BMI.

CONCLUSIONS

Our study suggests that there is a positive association between BMI at baseline and during follow-up with the risk of CHD among patients with type 2 diabetes. We indicate a U-shaped association between BMI at the last visit and the risk of CHD among women with type 2 diabetes.
Asymmetry and Leverage in Conditional Volatility Models
Authors: McAleer Michael
Published: September 2014

The three most popular univariate conditional volatility models are the generalized autoregressive conditional heteroskedasticity (GARCH) model of Engle (1982) and Bollerslev (1986), the GJR (or threshold GARCH) model of Glosten, Jagannathan and Runkle (1992), and the exponential GARCH (or EGARCH) model of Nelson (1990, 1991). The underlying stochastic specification to obtain GARCH was demonstrated by Tsay (1987), and that of EGARCH was shown recently in McAleer and Hafner (2014). These models are important in estimating and forecasting volatility, as well as in capturing asymmetry, which is the different effects on conditional volatility of positive and negative effects of equal magnitude, and purportedly in capturing leverage, which is the negative correlation between returns shocks and subsequent shocks to volatility. As there seems to be some confusion in the literature between asymmetry and leverage, as well as which asymmetric models are purported to be able to capture leverage, the purpose of the paper is three-fold, namely, (1) to derive the GJR model from a random coefficient autoregressive process, with appropriate regularity conditions; (2) to show that leverage is not possible in the GJR and EGARCH models; and (3) to present the interpretation of the parameters of the three popular univariate conditional volatility models in a unified manner.
Optimization of Alkaline Flocculation for Harvesting of Scenedesmus quadricauda #507 and Chaetoceros muelleri #862
Authors: Huo Shuhao , Wang Zhongming , Zhu Shunni , Cui Fengjie , Zou Bin , You Wenhua , Yuan Zhenhong , Dong Renjie
Published: September 2014

A response surface methodology (RSM) was used to evaluate the effects of pH and microalgal biomass concentration (BC) on alkaline flocculating activity for harvesting one freshwater green algae Scenedesmus quadricauda #507 and one marine diatom Chaetoceros muelleri #862. The pH value and BC were in range of 9.0–12.0 and 0.20–2.30 g/L, respectively. Very high regression coefficient between the variables and the response indicates excellent evaluation of experimental data by second-order regressions. Optimum conditions for flocculating activity were estimated as follows: (i) pH 11.6, BC 0.54 g/L for strain #507 and (ii) pH 11.5, BC 0.42 g/L for strain #862. The maximum flocculating activity was around 94.7% and 100%, respectively. Furthermore, the addition of synthetic ocean water (SOW) to the freshwater #507 culture can increase the flocculating activity from 82.13%–88.79% in low algae concentration (0.52 g/L) and 82.92%–95.60% in high concentration (2.66 g/L).
The Preparation of Graphene Oxide and Its Derivatives and Their Application in Bio-Tribological Systems
Authors: Li Jianchang , Zeng Xiangqiong , Ren Tianhui , Van der Heide Emile
Published: September 2014

Graphene oxide (GO) can be readily modified for particular applications due to the existence of abundant oxygen-containing functional groups. Graphene oxide-based materials (GOBMs), which are biocompatible and hydrophilic, have wide potential applications in biomedical engineering and biotechnology. In this review, the preparation and characterization of GO and its derivatives are discussed at first. Subsequently, the biocompatibility and tribological behavior of GOBMs are reviewed. Finally, the applications of GOBMs as lubricants in bio-tribological systems are discussed in detail.