bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partners in crime: the TGFβ and MAPK pathways in cancer progression
Authors: Chapnick Douglas A , Warner Lisa , Bernet Jennifer , Rao Timsi , Liu Xuedong 
Published: December 2011

Abstract
The TGFβ and Ras-MAPK pathways play critical roles in cell development and cell cycle regulation, as well as in tumor formation and metastasis. In the absence of cellular transformation, these pathways operate in opposition to one another, where TGFβ maintains an undifferentiated cell state and suppresses proliferation, while Ras-MAPK pathways promote proliferation, survival and differentiation. However, in colorectal and pancreatic cancers, the opposing pathways' mechanisms are simultaneously activated in order to promote cancer progression and metastasis. Here, we highlight the roles of the TGFβ and Ras-MAPK pathways in normal and malignant states, and provide an explanation for how the concomitant activation of these pathways drives tumor biology. Finally, we survey potential therapeutic targets in these pathways.
Velocity Attenuation and Force Transfer by a Single- and Double-Layer Claddings Made of Foam Materials
Authors: Karagiozova Dora 
Published: December 2011

The mechanism of air blast attenuation in a single- and double-layer sacrificial claddings comprising a steel cover plate and a foam core is examined applying an analytical and numerical analysis. In contrast to the commonly used approach to idealise the foam material by the rigid-perfectly plastic locking model, the unique relationship between the strains and stresses in foam materials exhibiting strain hardening is used in the present analytical model. The present analytical approach allows for a further explication of the compaction mechanism of the foam layers in sacrificial claddings. It is established that the blast energy is absorbed by the cladding core due to multiple reflections of the compaction wave. The proposed model of foam compaction is used to obtain the strains and stresses at the stationary end of the cladding within the reflected compaction wave. It is confirmed that among the equal mass claddings, those with lower density core transfer lower stresses to the stationary end when subjected to identical load. The use of double-layer claddings comprising foam layers with different densities is discussed. It is demonstrated that a reduction of the total thickness of the cladding can be achieved by placing a higher density foam layer near to the loaded end while lower density foam layer is preferable near to the stationary end of the cladding.
Characterizing the Material Properties of a Tube from a Lateral Compression Test
Authors: Rathnaweera Gayan , Durandet Yvonne , Ruan Dong , Kinoshita Shigeaki 
Published: December 2011

Material characterization is essential for finite element analysis (FEA) as the accuracy of the outputs of the simulation depends on the quality of the input material data. Conventional tests such as the uniaxial tensile test and uniaxial compression test have some drawbacks and limitations in characterizing tubular materials. In this paper, an improved methodology to determine the material properties of a tube based on lateral compression testis reported. Mechanical properties such as yield strength and elastic modulus were obtained from lateral compression experimental data. The material work hardening coefficient and work hardening exponent were obtained by inverse finite element analysis (IFEA). The proposed methodology was used to determine the material properties of an aluminium 6060T5 tube, and results were compared with those reported from uniaxial tensile tests. Comparison showed that the proposed methodology could be used to easily and accurately predict the tube material properties based on the lateral compression test.
Growth Differentiation Factor-15 in the Early Diagnosis and Risk Stratification of Patients with Acute Chest Pain
Authors: Schaub Nora , Reichlin Tobias , Twerenbold Raphael , Reiter Miriam , Steuer Stephan , Bassetti Stefano , Stelzig Claudia , Wolf Claudia , Winkler Katrin , Haaf Philip , Meissner Julia , Drexler Beatrice , Mueller Christian 
Published: December 2011

Abstract

BACKGROUND
Growth differentiation factor-15 (GDF-15) is a stress-responsive marker that might aid in the early diagnosis and risk stratification of patients with suspected acute myocardial infarction (AMI).

METHODS
In a prospective, international multicenter study, GDF-15, high-sensitivity cardiac troponin T (hs-cTnT), and B-type natriuretic peptide (BNP) were measured in 646 unselected patients presenting to the emergency department with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. The primary prognostic end point was all-cause mortality during a median follow-up of 26 months.

RESULTS
AMI was the adjudicated final diagnosis in 115 patients (18%). GDF-15 concentrations at presentation were significantly higher in AMI patients compared to patients with other diagnoses. The diagnostic accuracy of GDF-15 at presentation for the diagnosis of AMI as quantified by the area under the ROC curve (AUC) was lower (AUC 0.69, 95% CI 0.64–0.74) compared to hs-cTnT (AUC 0.96, 95% CI 0.94–0.98, P &lt; 0.001) and BNP (AUC 0.74, 95% CI 0.69–0.80, P = 0.02). A total of 55 deaths occurred during follow-up. GDF-15 predicted all-cause mortality independently of and more accurately than hs-cTnT [AUC 0.85 (95% CI 0.81–0.90) vs 0.77 (95% CI 0.72–0.83), P = 0.002] and BNP (AUC 0.75, 95% CI 0.68–0.82, P = 0.007). Net reclassification improvement was 0.15 (P = 0.01), and the absolute integrated discrimination improvement was 0.07, yielding a relative integrated discrimination improvement of 0.36 (P = 0.07).

CONCLUSIONS
GDF-15 predicts all-cause mortality in unselected patients with acute chest pain independently of and more accurately than hs-cTnT and BNP. However, GDF-15 does not seem to help in the early diagnosis of AMI.
Maturity and Impedance Analysis of Organic-Rich Shales
Authors: Prasad Manika , Mba Kenechukwu C. , McEvoy T. Elizabeth , Batzle Michael L. 
Published: December 2011

Summary
Organic-rich shales (ORSs) need to be studied in detail to understand the provenance and the generation of hydrocarbons from source rocks. In recent years, ORSs have gained importance as hydrocarbon resources as well. Successful exploration and production programs for ORSs need reliable identification of their kerogen content as well as maturity through indirect seismic methods. However, the properties of kerogen are poorly understood, so predictions about maturity and rock-kerogen systems remain a challenge. Assessment of maturity from indirect measurements can be greatly enhanced by establishing and exploiting correlations between physical properties, microstructure, and kerogen content.
We show correlations between the impedance microstructure of ORSs and their maturity and elastic properties. We have used scanning acoustic microscopy to analyze and map the impedance microstructure in ORSs. We quantified textural properties in the images and related these textural properties to maturity and to impedance from acoustic-wave propagation measured at centimeter scales. This combined study of acoustic properties and microstructures of ORSs gives important insight into changes resulting from kerogen maturation. We introduce a modified porosity term and find that (1) there is a significant correlation between velocity and modified porosity of all ORSs; (2) imaging and quantifying microscale impedance texture and contrast in the images allow us to correlate them with ultrasonic measurements on a centimeter scale; and (3) textural heterogeneity, elastic impedance, velocity, and density increase with increasing shale maturity.
We also discuss possible methods to predict maturity from impedance on the basis of understanding the changes resulting from maturity in well-log response, core measurements, and microstructure of ORSs. Our work has important bearing on developing successful production and stimulation methodologies.
Alkaline/Surfactant/Polymer Flood: From the Laboratory to the Field
Authors: Stoll W. M. , al Shureqi H.. , Finol J.. , Al-Harthy S. A. , Oyemade S.. , de Kruijf A.. , van Wunnik J.. , Arkesteijn F.. , Bouwmeester R.. , Faber M. J. 
Published: December 2011

Summary
After two decades of relative calm, chemical enhanced-oil-recovery (EOR) technologies are currently revitalized globally. Techniques such as alkaline/surfactant/polymer (ASP) flooding, originally developed by Shell, have the potential to recover significant fractions of remaining oil at a CO2 footprint that is low compared with, for example, thermal EOR, and they do not depend on a valuable miscible agent such as hydrocarbon gas. On the other hand, chemical EOR technologies typically require large quantities of chemical products such as surfactants and polymers, which must be transported to, and handled safely in, the field.
Despite rising industry interest in chemical EOR, until today only polymer flooding has been applied on a significant scale, whereas applications of surfactant/polymer or alkaline ASP flooding were limited to multiwell pilots or to small field scale. Next to the oil-price fluctuations of the past two decades, technical reasons that discouraged the application of chemical EOR are excessive formation of carbonate or silica scale and formation of strong emulsions in the production facilities.
Having identified significant target-oil volumes for ASP flooding, Petroleum Development Oman (PDO), supported by Shell Technology Oman, carried out a sequence of single-well pilots in three fields, sandstone and carbonate, to assess the flooding potential of tailor-made chemical formulations under real subsurface conditions, and to quantify the benefits of full-field ASP developments.
This paper discusses the extensive design process that was followed. Starting from a description of the optimization of chemical phase behavior in test-tube and coreflood experiments, we elaborate how the key chemical and flow properties of an ASP flood are captured to calibrate a comprehensive reservoir-simulation model. Using this model, we evaluate PDO's single-well pilots and demonstrate how these results are used to design a pattern- flood pilot.
A Comprehensive Model of High-Rate Matrix-Acid Stimulation for Long Horizontal Wells in Carbonate Reservoirs: Part I—Scaling Up Core-Level Acid Wormholing to Field Treatments
Authors: Furui K.. , Burton R.C.. C. , Burkhead D.W.. W. , Abdelmalek N.A.. A. , Hill A.D.. D. , Zhu D.. , Nozaki M.. 
Published: December 2011

Summary
Matrix-acidizing models have traditionally underpredicted acid-stimulation benefits because of underprediction of wormhole penetration and the corresponding magnitude of completion-skin factors in vertical wells. For long horizontal wells drilled in carbonate reservoirs, productivity enhancement is a function of acid placement and effective wormhole penetration. However, prediction of wormhole penetration requires more effective analysis than that provided by current industry models. This paper presents results of matrix-acid modeling work for horizontal wells and describes a practical engineering tool for analyzing the progress of matrix-acid stimulation in carbonate reservoirs.
The wormhole-growth model is based on the Buijse and Glasbergen empirical correlation. Combining with the mechanistic model of the wormhole propagation based on acid transport and fluid loss from a single wormhole, a modified Buijse-Glasbergen wormhole-growth model is developed that relates the wormhole growth rate to the in-situ injection velocity at the tip of the dominant wormhole. The wormhole constitutive model developed in this study also accounts for core-size dependencies seen in laboratory acid-flood experiments. A semianalytical flow correlation is derived for estimating interstitial velocities at the tip of the dominant wormholes based on a number of 3D FEM simulation analyses, accounting for more realistic flow regimes (radial and spherical flow) typically observed in field application. The scaleup procedure developed in this study extends the wormhole geometry and penetration from laboratory flow tests on small cores to field-sized treatments.
The scaleup procedure developed in this work can be applied to cemented and uncemented horizontal wells, including barefoot and perforation-cluster completions typically employed in carbonate reservoirs. Application of this modeling shows that acid wormholing through carbonate formations can provide significant stimulation, resulting in post-stimulation skins as low as–3.5 to–4.0 vs. previously predicted values in the –1.0 to–2.0 range.
Drillpipe Cutting at Ultrahigh Pressure Proven for Remediating Deepwater Stuck-Pipe Hazards
Authors: Seguras John 
Published: December 2011

Summary
Efficient separation of stuck drillstrings with proven results is a must for deepwater wells where depths can reach 35,000 ft and daily rates often exceed USD 1,000,000. Operators want proven results instead of theoretical calculations or critical-path experimentation during a stuckpipe hazard event. Historical pipe cutting or severing has been hindered for decades by high bottomhole pressures (BHPs) and internal-diameter restrictions. Chemical cutters and plasma cutters are most affected by the effect of hydrostatic pressure on their method of pipe separation, while jet cutters and severing tools’ explosive charges could overcome more BHP. After leaping the 20,000-psi hurdle, we were still limited to 25,000 psi or less and had unproven products until now.
From conceptual development to laboratory data, this paper will describe the need for and development, testing, and results of jet cutters and severing tools for use in ultrahigh-pressure environments up to 30,000 psi for today's deepwater, ultradeep-well market. Designing and building of a new, first-of-its-kind test vessel allowed for visualization and verification of actual separation of drillstring components at BHPs with zero tension applied.
Extrapolation of data from previous cutter designs at lower pressure ratings allowed us to tailor each cutter size and charge quantity for the pipe thicknesses and test pressures desired. The material component of the cutter housing and the timing of explosive initiation are critical for the cutters to withstand the descent through the drillstring components and the constantly increasing wellbore pressure and still provide an accurate, efficient detonation for separating the thick metal wall of the pipe. Laboratory testing proved that jet cutting and severing drillstring tubular components are achievable at pressures up to 30,000 psi in drillpipe and heavyweight-drillpipe (HWDP) bottomhole drilling assemblies.
Substantial cost and critical-path time savings for deepwater operators can be realized during stuck-pipe incidents by using tested technology proven to separate drillstring components at BHPs up to 30,000 psi.
Retardation of CO2 Caused by Capillary Pressure Hysteresis: A New CO2 Trapping Mechanism
Authors: Altundas Y.B.. B. , Ramakrishnan T.S.. S. , Chugunov Nikita , de Loubens Romain 
Published: December 2011

Summary
Containment security of geologically stored CO2 is improved substantially through trapping mechanisms. Therefore, to simulate the potential viability of a storage site, it is necessary to account for immobilization processes. In this paper, we focus on a quantitative measure for the contribution of hysteresis in reducing plume transport, with particular emphasis on capillary-pressure-induced migration retardation. Rocks with large pore-body-to-throat-size ratio, or a low permeability, are the best candidates for this mechanism to be operative.
In the present work, a self-consistent relative permeability and capillary pressure hysteresis model is incorporated within a simulator. With this model, it is possible to compare and contrast hysteresis-induced retardation to other mechanisms of trapping. The self-consistent parameterization of all of the transport properties is used to quantify sensitivity compactly. The sensitivity of the CO2-plume shape and the amount of CO2 trapped to the strength of the capillary pressure hysteresis is also described.
Simulated results show that the CO2-plume shapes with and without capillary pressure hysteresis are significantly different. As expected, capillary pressure hysteresis retards the buoyant transport of the CO2 plume. Although a portion of the CO2 is connected, and therefore not residual, the plume remains immobile for all practical purposes. Also, because of the decreased driving potential, gravity tonguing below the caprock is reduced in comparison to the case without capillary pressure hysteresis, thus suggesting enhanced storage efficiency. However, the total dissolution of CO2 in saline water is reduced because of the reduced contact area with the brine. Thus, one mechanism of containment is offset by the other.
Inclusion of accurate hysteresis models is important for qualifying storage sites constrained by spatial-domain limits. It is anticipated that site-acceptability criteria would change as a result of this study, thereby impacting risk evaluation.
Stabilizing Viscoelastic Surfactants in High-Density Brines
Authors: van Zanten R.. 
Published: December 2011

Summary
Viscoelastic-surfactant (VES) systems are the preferred gelling and viscosity-generating agents for fluids used in the production zone because of their nondamaging effects on the reservoir. Polymer gels have relatively higher rock-retention values and can often damage the invaded zone, in most cases requiring acid treatment to remove. In contrast, VES systems behave as "equilibrium" or "living" polymers, and their viscosity can be reduced by contact with the produced hydrocarbons or with an internal breaker. This can eliminate the need for remedial treatments, greatly reducing operating cost/time and damage to the formation.
Cationic, anionic, and cationic/anionic VES systems have historically demonstrated limitations in high-density brines. Electrostatic screening generally reduces the viscosity or causes phase separation. Many surfactants generally have low salt tolerance and minimal to zero tolerance of divalent brines. Most surfactants exhibit a dramatic decrease in viscosity after a certain concentration of salt is reached and even phase separation in some cases.
A novel method has been developed to stabilize different VES packages in high-density completion brines. By controlling the curvature of surfactant aggregates using low-molecular-weight surfactant polymers, nanometer-scale manipulation of the phase behavior is achieved. We have viscosified mono-and divalent high-density brines using cationic, anionic, and catanionic mixtures that were previously considered ineffective. This unlocks a vast range of surfactants for use in high-density completion brines, fracturing/stimulation/acidizing fluids, and sand-control operations.
This paper details the laboratory work performed to develop VES packages for fluids ranging from fresh water to completion brines. Extensive rheology experiments have been run on several fluids, showing the viscoelasticity of these systems. The selfbreaking nature of VES systems when in contact with hydrocarbons or exposed to a built-in breaker has also been demonstrated by laboratory experiment.
Optimal Well Placement Under Uncertainty Using a Retrospective Optimization Framework
Authors: Wang Honggang , Ciaurri David Echeverría , Durlofsky Louis J. , Cominelli Alberto 
Published: December 2011

Summary
Subsurface geology is highly uncertain, and it is necessary to account for this uncertainty when optimizing the location of new wells. This can be accomplished by evaluating reservoir performance for a particular well configuration over multiple realizations of the reservoir and then optimizing based, for example, on expected net present value (NPV) or expected cumulative oil production. A direct procedure for such an optimization would entail the simulation of all realizations at each iteration of the optimization algorithm. This could be prohibitively expensive when it is necessary to use a large number of realizations to capture geological uncertainty. In this work, we apply a procedure that is new within the context of reservoir management—retrospective optimization (RO)—to address this problem. RO solves a sequence of optimization subproblems that contain increasing numbers of realizations. We introduce the use of k -means clustering for selecting these realizations. Three example cases are presented that demonstrate the performance of the RO procedure. These examples use particle swarm optimization (PSO) and simplex linear interpolation (SLI)-based line search as the core optimizers (the RO framework can be used with any underlying optimization algorithm, either stochastic or deterministic). In the first example, we achieve essentially the same optimum using RO as we do using a direct optimization approach, but RO requires an order of magnitude fewer simulations. The results demonstrate the advantages of cluster-based sampling over random sampling for the examples considered. Taken in total, our findings indicate that RO using cluster sampling represents a promising approach for optimizing well locations under geological uncertainty.
Multipoint Statistical Characterization of Geologic Facies from Dynamic Data and Uncertain Training Images
Authors: Khodabakhshi Morteza , Jafarpour Behnam 
Published: December 2011

Abstract
Discrete geologic features that contribute to preferential flowpaths or act as flow barriers are rarely amenable to second-order descriptions. Using a conceptual model or training image (TI), multipoint statistics (MPS) provides a systematic approach to describe the higher-order spatial statistics of discrete geologic features. Conditioning MPS facies realizations on flow data poses a challenging nonlinear inverse problem, primarily because of the nonlinear relation between facies properties and flow response measurements. Since MPS simulated facies imitate the spatial patterns in the TI, the quality of the generated facies depend on the reliability of the TI. However, given the uncertainty in the knowledge used to construct a TI, it is imperative to account for and represent the uncertainty in any given TI. One approach to account for TI uncertainty is to use multiple TIs to cover the expected range of structural variability in geologic facies. When several TIs are used to represent the uncertainty in the conceptual geologic model for a given field, flow data may be used to quantify the importance of different TIs. Here, we present a new method for adaptively sampling conditional facies from multiple uncertain TIs. By applying a fast flow-based clustering approach, we show that one can adaptively sample facies realizations from multiple TIs to honor the observed flow data. We apply a probability conditioning method (PCM) to invert the flow data to construct a facies probability map that can be included in drawing conditional facies realizations from each TI. We illustrate that the proposed adaptive sampling scheme can be used to weigh different TI s according to their performance in matching the flow data. We demonstrate the suitability of the proposed method using numerical experiments in fluvial formations where several TIs are used to account for the uncertainty in facies structural connectivity.