bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using Computational Fluid Dynamics to Accurately Determine Ball Drop Times and Velocities in Fracturing Systems
Authors: De Mas Carolina , Pitts Michael J. , Jamieson David 
Published: February 2013

Abstract
Computational Fluid Dynamics (CFD) has been used as a means of accurately determining the time and displacement volume of balls used to activate multiple ports in a multi-zone fracturing system that is 18,000 feet long.
Hydraulic fracturing techniques are complex and highly evolving. In such processes, ball-operated sliding sleeves are a means to access multiple zones in the formation, creating fractures into which proppant is pumped. The success of placement in such systems depends upon accurate calculation of the time required for a ball to be pumped from the topside to the multiple ball seats over distances of tens of thousands of feet. It is vital that any treatment is not over displaced and thus accurate volume and timing is essential.
Using CFD unsteady simulations for validation, a simple mathematical model was created that allowed an accurate, quick-response evaluation of the time taken for a ball to be pumped through a completion. These simulations involved the use of Dynamic Fluid Body Interaction (DFBI), morphing and overset computational meshes as well as lagrangian particle-based physics. A number of challenges were met with innovative solutions; the completion followed a complex path and was over 18,000 ft in length, the duration of the study was very short, the fluid within which the ball was immersed was non-Newtonian and the particle-based fluid-particle interaction models used required validation.
This study brought together many applications areas including completion string design, the formation fracture process, CFD numerical methods, simulation management, external aerodynamics and CFD software development. Results of the simulations were compared to full-sized testing and field data.
Competition Between Transverse And Axial Hydraulic Fractures In Horizontal Wells
Authors: Lecampion Brice , Abbas Safdar , Prioul Romain 
Published: February 2013

Abstract
Most horizontal wells in unconventional reservoirs are drilled in the direction of the minimum stress. The preferred far-field fracture orientation thus favors hydraulic fractures transverse to the wellbore. The near-wellbore stress concentration, however, sometimes favors the initiation of fractures in a plane defined by the well axis. Transverse and axial hydraulic fractures can thus both initiate in some situations and cause significant near-wellbore tortuosity. We investigate the competition between these two types of fractures by comparing their energy requirement during hydraulic fracture initiation and propagation. First, we investigate the limiting cases of slow and fast pressurization where fluid flow and fracture mechanics uncouple. We then use recently developed numerical models for the initiation and propagation of hydraulic fractures from an open hole accounting for fluid flow in the newly created crack, wellbore stress concentration and injection system compressibility.
Compared to a simple tensile stress analysis, the methodology described here provides a way to quantify the occurrence of only transverse or both transverse and axial hydraulic fractures as well as the maximum length of the axial fractures in the latter case. Based on dimensional analysis and numerical simulations for a range of relevant formation properties and far-field stress conditions, our results show that the critical defect length that favors transverse fracture over longitudinal is less than a borehole radius in the slow pressurization limit. For realistic injection conditions, if the initial defect length favors axial fractures, the distance over which transverse fractures become energetically favorable can become much larger than its slow pressurization value, especially for large dimensionless viscosity. Smaller pressurization rate and less viscous fluid ultimately favor the propagation of transverse fractures compared to axial ones.
Application of Multivariate Analysis and Geographic Information Systems Pattern-Recognition Analysis to Production Results in the Bakken Light Tight Oil Play
Authors: LaFollette Randy F. , Izadi Ghazal , Zhong Ming 
Published: February 2013

Abstract
Even after the drilling of several thousand horizontal Bakken wells in Montana and North Dakota, geologists and engineers question whether their companies are using the appropriate completion and stimulation parameters for their reservoir in their particular location. Answers to this fundamental question can be difficult to come by using univariate statistical techniques. Thus, more advanced and integrated methods of analysis may be needed to achieve sound interpretations. The purpose of this paper is to apply multivariate statistical modeling in conjunction with Geographic Information Systems (GIS) pattern recognition work to update and expand previous Bakken data-mining efforts.
The investigation began by updating Bakken Formation data using both proprietary and public information. The different data sets were loaded into a common database and put through quality control sanity checks. Production proxies, such as maximum oil rate in the first 12 producing months, were selected and merged with the other data. Final data sets were then subjected to analysis in both an open-source statistical analysis environment and a commercial (GIS) application.
The integration of the two analysis and interpretation methods highlighted the importance of using well location as a proxy for reservoir quality when working with data sets that lack such measurements. The use of multivariate statistical analysis allowed modeling the impact of particular completion and stimulation parameters on the production outcome by averaging out the impact of all other variables in the system.
This work is believed to be unique in its combination of multivariate statistics and GIS pattern recognition to address questions of well optimization in unconventional reservoirs and that is its application. It is significant in that it expands the scope of prior studies that did not take full advantage of multivariate statistical methods.
Fair Value Accounting for Financial Instruments: Does It Improve the Association between Bank Leverage and Credit Risk?
Authors: Blankespoor Elizabeth , Linsmeier Thomas J. , Petroni Kathy R. , Shakespeare Catherine 
Published: February 2013

ABSTRACTMany have argued that financial statements created under an accounting model that measures financial instruments at fair value would not fairly represent a bank's business model. In this study we examine whether financial statements using fair values for financial instruments better describe banks' credit risk than less fair-value-based financial statements. Specifically, we assess the extent to which various leverage ratios, which are calculated using financial instruments measured along a fair value continuum, are associated with various measures of credit risk. Our leverage ratios include financial instruments measured at (1) fair value; (2) U.S. GAAP mixed-attribute values; and (3) Tier 1 regulatory capital values. The credit risk measures we consider are bond yield spreads and future bank failure. We find that leverage measured using the fair values of financial instruments explains significantly more variation in bond yield spreads and bank failure than the other less fair-value-based leverage ratios in both univariate and multivariate analyses. We also find that the fair value of loans and deposits appear to be the primary sources of incremental explanatory power.Data Availability: All data are publicly available from the sources indicated in the paper.
Evidence that Market Participants Assess Recognized and Disclosed Items Similarly when Reliability is Not an Issue
Authors: Bratten Brian , Choudhary Preeti , Schipper Katherine 
Published: February 2013

ABSTRACT
We provide evidence that disclosed items are not processed differently from recognized items when the disclosures are salient, not based on management estimates, and amenable to simple techniques for imputing as-if recognized amounts. For a sample of firms with both capital and operating leases, we find that as-if recognized amounts for leases are generally reliable and that both recognized lease obligations and disclosed lease obligations are associated with proxies for costs of debt and equity. The magnitudes of these associations are not statistically different across accounting treatments, suggesting that market participants impound as-if recognized operating lease obligations and recognized capital lease obligations similarly into costs of capital. Conditioning on the reliability of as-if recognized operating lease obligations, we find a difference in the association between recognized versus as-if recognized lease obligations and proxies for the costs of debt and equity when the operating lease disclosures are less reliable.
Data Availability: Data used are available from public sources identified in the study.
Extended Euclidean Algorithm and CRT Algorithm
Authors: Okazaki Hiroyuki , Aoki Yosiki , Shidama Yasunari 
Published: February 2013

Summary
In this article we formalize some number theoretical algorithms, Euclidean Algorithm and Extended Euclidean Algorithm [9]. Besides the a gcd b, Extended Euclidean Algorithm can calculate a pair of two integers (x, y) that holds ax + by = a gcd b. In addition, we formalize an algorithm that can compute a solution of the Chinese remainder theorem by using Extended Euclidean Algorithm. Our aim is to support the implementation of number theoretic tools. Our formalization of those algorithms is based on the source code of the NZMATH, a number theory oriented calculation system developed by Tokyo Metropolitan University [8].
Schooling entrepreneurs: Entrepreneurship, governmentality and education policy in Sweden at the turn of the millennium
Authors: Dahlstedt Magnus , Hertzberg Fredrik 
Published: February 2013

ABSTRACT
Departing from Michel Foucault’s concept of governmentality, the focus of this article is the introduction of entrepreneurial education in Swedish education policy at the turn of the millennium. We analyze the various meanings attached to the concepts of “entrepreneur” and “entrepreneurship” in education policy documents, as well as the main arguments for introducing entrepreneurial education. In policy documents, the “entrepreneur” is portrayed as being flexible, creative, enterprising and independent, as having the ability to take initiative, solve problems and make decisions. Here, there is an emphasis made on economical utility, and its priority over other values. With an increasing mobilization of entrepreneurship in school, previous pedagogical and educational doctrines - focusing on equality, universalism and redistribution - are challenged. Other visions, stating other educational purposes and goals emerge. In the vision of the entrepreneurial school, it becomes logical and natural to emphasize the value education has for the economic system. In conclusion, entrepreneurial education may be seen as a particular kind of governmentality, connecting students and their subjectivity to the rationality of the market - fostering subjects in line with the imperatives of the “advances liberal society”.
Educational reform in Greece: Central concepts and a critique
Authors: Gounari Panayota , Grollios George 
Published: February 2013

Abstract
The case of Greece as the most recent neoliberal experiment can provide valuable insights not only about a generalized attack on the welfare state and the public good, but also about the radical changes in public education that are altering its public mission, vision, and goals. In this paper first we trace the educational landscape in Greece as it emerges both from the reform in primary and secondary education and from the new law 4009 on higher education. The ongoing government discourse on education is shaped and constructed along the lines of a market- driven society and unapologetically espouses the neoliberal dogma that aims to convert education into training, universities into corporations, knowledge into a service or commodity, and students into clients. We further examine the official public discourse as illustrated in government documentation in an attempt to map out the marked shift from the university as a public good to the university as corporate entity, and highlight the particular ways in which this is done. The new educational legislation sets the stage for an education where the individual will thrive through relentless competition, where collectivity is abolished, where only “useful” knowledge counts and where “quality” and “excellence” serve as the excuse for a corporate standardization of the university and the academic life and thought.
Influence of the Flow Rate of Oxidising Atmosphere on the Flame Spread Rate on the Surface of Organic Setlled Dust
Authors: Martinka Jozef , Balog Karol , Hrušovský Ivan , Valentová Veronika 
Published: February 2013

Abstract
The presented paper deals with determining the influence of the flow rate of oxidising atmosphere on the flame spread along the surface of the organic settled dust layer. We determined the rate of the flame spread on the surface of the organic settled dust layer (whole grain rye and spelt flour) with absolute moisture of 10 % wt., for the flow rates of oxidising atmosphere 1, 3, 5 and 10 cm/s. Pure oxygen was used as an oxidising atmosphere. The obtained results suggest that there exists a power relationship of the flame spread rate along the surface of organic settled dust layer to the flow rate of the oxidising mixture. The method described is suitable for the relative comparison of the organic settled dust layer from the point of its ability to spread the flame and the influence of the air flow rate on this process.
From Candidate to President: Obama’S Discourse Two Years Later
Authors: Bran Ramona , Pele Andreea 
Published: February 2013

Abstract
The article explores Barack Obama’s most notable speeches after becoming president. The authors intend to write a sequel to their 2009 paper Yes We Can: A New American Identity in the Speeches of Barack Obama, which looked at Obama’s campaign discourse, and investigate if his rhetoric has changed in the first half of his mandate.
I’m Lovin’ it
Authors: Cehan Anca 
Published: February 2013

Abstract
The paper presents the special meanings and many-sided implications that can be conjectured from the use of a stative verb in the progressive, and the linguistic difficulties encountered in analysing McDonald’s slogan. It reviews the behaviour of to love when tested for stativeness and concludes that as a “progressive stative” verb it can be cleverly exploited for fresh emotional implications.
Prosody in Elicitations: A Study of Intonation in BBC Talk Radio Shows
Authors: Herczeg-Deli Ágnes 
Published: February 2013

Abstract
The paper is concerned with the prosodic features of non-literal language use in indirect elicitations in radio talk. It will be demonstrated how intonation becomes mirror of some contextual factors, and how the prosodic features of elicitations can corroborate the speaker’s meaning manifested through certain lexico-grammatical elements in the discourse.
An Eastern European Traveler to Paradise. Los Angeles in Petru Comarnescu’s American Travelogue From 1934
Authors: Lolea Georgiana 
Published: February 2013

Abstract
Published in 1934, Petru Comarnescu’s American journal offers both a fresh take on the Californian milieu of the late 20s and the beginning of the 30s, and open-minded perspectives on the New World. The present paper analyzes how the Romanian intellectual put together the historical, social and cultural pieces of the complex city puzzle in his bold attempt at recreating the atmosphere of the chameleonic metropolis of Los Angeles.
Quality of Systematic Reviews on Specific Spinal Stabilization Exercise for Chronic Low Back Pain
Authors: Haladay Douglas E. , Miller Sayers J. , Challis John , Denegar Craig R. 
Published: February 2013

Study Design Systematic literature review. Objective To evaluate the quality of systematic reviews (SRs) on specific stabilization exercises for chronic low back pain (LBP). Background Multiple SRs regarding the effectiveness of lumbar stabilization exercises for people with chronic LBP have been published. As more SRs are published, the more it is recognized that, like other forms of research, methodological quality affects the validity of, and conclusions drawn from, the data. Methods A search of MEDLINE, CINAHL, and Embase was completed. Additionally, the PEDro database was screened and hand searching was completed. Included SRs had to contain randomized controlled trials examining a specific stabilization exercise program for the treatment of chronic LBP. Additionally, the assessed outcome measures had to include pain and/or disability measures. Literature reviews and clinical practice guidelines were excluded. Three reviewers independently assessed each SR for methodological quality. Results The search produced 665 SRs for review, of which 8 fulfilled the inclusion criteria. Consensus quality assessment scores ranged from 13/26 to 26/26, with an average of 20.7 points. Percent agreement and kappa values for individual criteria scores ranged from 50% to 92% and 0.25 to 0.85, respectively. Agreement was moderate to substantial across individual items, except for criterion 1. The intraclass correlation coefficient for overall score was 0.98 (95% confidence interval: 0.96, 0.99). Conclusion This review of SRs identified several high-quality reviews that indicated some benefit of specific stabilization exercise programs for patients with nonspecific chronic LBP. Level of Evidence Therapy, level 1a. J Orthop Sports Phys Ther 2013;43(4):242–250. Epub 14 January 2013. doi:10.2519/jospt.2013.4346
Falls Among Patients Who Had Elective Orthopaedic Surgery: A Decade of Experience From a Musculoskeletal Specialty Hospital
Authors: Mandl Lisa A. , Lyman Stephen , Quinlan Patricia , Bailey Tina , Katz Jacklyn , Magid Steven K. 
Published: February 2013

Study Design Retrospective cohort study. Objective To evaluate falls among elective orthopaedic inpatients at a musculoskeletal hospital. Background Falls are the most commonly reported hospital incidents. Approximately 30% of in-hospital falls result in minor injury, and up to 8% of falls result in moderate to severe injury. Given the projected rise in elective orthopaedic procedures, it is important to better understand fall patterns in this population. Methods A retrospective review of electronic medical records and patient charts (2000–2009) was conducted to identify falls in patients admitted for elective orthopaedic procedures. Results There were 868 falls among orthopaedic patients older than 18 years. The fall rate was 0.9% of admissions, or 2.0 falls per 1000 inpatient days. The average age of the patients who had fallen was 68 years, and 57.6% were women. Knee replacements (38.2%), spine procedures (18.5%), and hip replacements (14.7%) were the procedures most commonly associated with falls. Three hundred eighty-six falls (45.8%) involved bathroom usage. One hundred ten first falls (13.1%) resulted in injuries. Twenty-eight falls (3.3%) resulted in serious events, including 5 returns to the operating room, 3 transfers to a higher level of care, 14 prosthesis dislocations, 6 fractures, 2 intracranial bleeds, and 1 hemorrhage. Patients with serious injuries were more likely to fall earlier (mean postoperative days, 2.7 versus 4.1; mean difference, 1.4 days; 95% confidence interval: 0.51, 2.3; P = .003) and to have had hip replacement (odds ratio = 3.7; 95% confidence interval: 1.7, 8.2). Serious injuries were not associated with body mass index, age, gender, hospital location, day, or fall history. Conclusion Falls are avoidable events that are poorly described among orthopaedic patients having elective procedures. This large series identifies hip replacement patients as being at almost 4-fold risk of having a serious adverse event after falling. Larger prospective trials are needed to confirm results and to inform prevention strategies. J Orthop Sports Phys Ther 2013;43(2):91–96. doi:10.2519/jospt.2013.4349
Risk Factors for Persistent Problems Following Acute Whiplash Injury: Update of a Systematic Review and Meta-analysis
Authors: Walton David M. , MacDermid Joy C. , Giorgianni Anthony A. , Mascarenhas Joanna C. , West Stephen C. , Zammit Caroline A. 
Published: February 2013

Study Design Systematic review and meta-analysis. Objective To update a previous review and meta-analysis on risk factors for persistent problems following whiplash secondary to a motor vehicle accident. Background Prognosis in whiplash-associated disorder (WAD) has become an active area of research, perhaps owing to the difficulty of treating chronic problems. A previously published review and meta-analysis of prognostic factors included primary sources up to May 2007. Since that time, more research has become available, and an update to that original review is warranted. Methods A systematic search of international databases was conducted, with rigorous inclusion criteria focusing on studies published between May 2007 and May 2012. Articles were scored, and data were extracted and pooled to estimate the odds ratio for any factor that had at least 3 independent data points in the literature. Results Four new cohorts (n = 1121) were identified. In combination with findings of a previous review, 12 variables were found to be significant predictors of poor outcome following whiplash, 9 of which were new (n = 2) or revised (n = 7) as a result of additional data. The significant variables included high baseline pain intensity (greater than 5.5/10), report of headache at inception, less than postsecondary education, no seatbelt in use during the accident, report of low back pain at inception, high Neck Disability Index score (greater than 14.5/50), preinjury neck pain, report of neck pain at inception (regardless of intensity), high catastrophizing, female sex, WAD grade 2 or 3, and WAD grade 3 alone. Those variables robust to publication bias included high pain intensity, female sex, report of headache at inception, less than postsecondary education, high Neck Disability Index score, and WAD grade 2 or 3. Three existing variables (preaccident history of headache, rear-end collision, older age) and 1 additional novel variable (collision severity) were refined or added in this updated review but showed no significant predictive value. Conclusion This review identified 2 additional prognostic factors and refined the estimates of 7 previously identified factors, bringing the total number of significant predictors across the 2 reviews to 12. These factors can be easily identified in a clinical setting to provide estimates of prognosis following whiplash. Level of Evidence Prognosis, level 1a. J Orthop Sports Phys Ther 2013;43(2):31–43. Epub 14 January 2013. doi:10.2519/jospt.2013.4507