bluuebunny/crossref_metadata_2025 huggingface dataset:
Neurogenetic Variations in Norepinephrine Availability Enhance Perceptual Vividness
Authors: Todd Rebecca M. , Ehlers Mana R. , Müller Daniel J. , Robertson Amanda , Palombo Daniela J. , Freeman Natalie , Levine Brian , Anderson Adam K.
Published: April 2015

Emotionally salient aspects of the world are experienced with greater perceptual vividness than mundane ones; however, such emotionally enhanced vividness (EEV) may be experienced to different degrees for different people. We examined whether BOLD activity associated with a deletion variant of theADRA2bgene coding for the α2b adrenoceptor modulates EEV in humans. Relative to noncarriers,ADRA2bdeletion carriers showed higher levels of perceptual vividness, with the ventromedial prefrontal cortex (VMPFC) showing greater modulation by EEV. Deletion carriers were also more sensitive to the featural salience of the images, suggesting a more pervasive role of norepinephrine in perceptual encoding. Path analysis revealed that, whereas a simple model by which the amygdala modulated the lateral occipital complex best characterized EEV-related activity in noncarriers, contributions of an additional VMPFC pathway best characterized deletion carriers. Thus, common norepinephrine-related neurogenetic differences enhance the subjective vividness of perceptual experience and its emotional enhancement.
Specificity of Repetition Priming: The Role of Chemical Coding
Authors: Friedman Allyson K. , Weiss Klaudiusz R. , Cropper Elizabeth C.
Published: April 2015

We investigate stimulus specificity of repetition priming in a tractable model system; the feeding network ofAplysia. Previous studies primarily focused on an aspect of behavior that is altered during ingestive priming, radula opening. Priming of radula opening occurs when two modulatory peptides [feeding circuit activating peptide (FCAP) and cerebral peptide-2 (CP-2)] are released from the cholinergic command-like neuron cerebral buccal interneuron 2. Effects of FCAP/CP-2 on radula opening motor neurons are cAMP mediated. The present experiments sought to determine whether FCAP/CP-2 and cAMP are also involved in the priming of radula opening during an incompatible activity, i.e., during egestive motor programs. Egestive priming is induced when motor programs are triggered by afferents with processes in the esophageal nerve. We demonstrate that egestive priming is not FCAP/CP-2 mediated. Instead, it is induced by an unrelated peptide (small cardioactive peptide), which exerts PKC-mediated effects. Our data, therefore, suggest that different feeding motor programs are primed via actions of different sets of intercellular and intracellular substances. We suggest that this accounts for the stimulus specificity that can be characteristic of repetition priming. Different stimuli activate different central pattern generator inputs. These inputs release different modulators, which induce functionally distinct motor programs.
Altered Basolateral Amygdala Encoding in an Animal Model of Schizophrenia
Authors: Hernandez Alex , Burton Amanda C. , O'Donnell Patricio , Schoenbaum Geoffrey , Roesch Matthew R.
Published: April 2015

It has been proposed that schizophrenia results, in part, from the inappropriate or spurious attribution of salience to cues in the environment. We have recently reported neural correlates of salience in the basolateral amygdala (ABL) of rats during learning in an odor-guided discrimination task. Here we tested whether this dopamine-dependent salience signal is altered in rats with neonatal ventral hippocampal lesions (NVHLs), a rodent model of schizophrenia. We found that ABL signals related to violations in reward prediction were only mildly affected by NVHL; however, neurons in rats with NVHLs showed significantly stronger selectivity during odor sampling, particularly for the more salient large-reward cue. The elevated cue-evoked activity in NVHL rats was correlated with heightened orienting behavior and also with changes in firing to the shifts in reward, suggesting that it reflected abnormal signaling of the large reward-predicting cue's salience. These results are broadly consistent with the proposal that schizophrenics suffer from enhanced signaling of salience.
Gene Expression by Mouse Inner Ear Hair Cells during Development
Authors: Scheffer Déborah I. , Shen Jun , Corey David P. , Chen Zheng-Yi
Published: April 2015

Hair cells of the inner ear are essential for hearing and balance. As a consequence, pathogenic variants in genes specifically expressed in hair cells often cause hereditary deafness. Hair cells are few in number and not easily isolated from the adjacent supporting cells, so the biochemistry and molecular biology of hair cells can be difficult to study. To study gene expression in hair cells, we developed a protocol for hair cell isolation by FACS. With nearly pure hair cells and surrounding cells, from cochlea and utricle and from E16 to P7, we performed a comprehensive cell type-specific RNA-Seq study of gene expression during mouse inner ear development. Expression profiling revealed new hair cell genes with distinct expression patterns: some are specific for vestibular hair cells, others for cochlear hair cells, and some are expressed just before or after maturation of mechanosensitivity. We found that many of the known hereditary deafness genes are much more highly expressed in hair cells than surrounding cells, suggesting that genes preferentially expressed in hair cells are good candidates for unknown deafness genes.
Female-specific regulation of skeletal muscle mass by USP19 in young mice
Authors: Ogawa Masahiro , Kitakaze Tomoya , Harada Naoki , Yamaji Ryoichi
Published: April 2015

17β-estradiol (E2) is thought to be responsible for sex-specific differences in skeletal muscle mass. The biological function of E2 is exerted through its binding to estrogen receptor α (ERα). The expression of ubiquitin-specific peptidase 19 (USP19) is upregulated during muscle atrophy and by E2-activated ERα. Here, we investigated the involvement of USP19 in sex difference in muscle mass in young mice. Knockdown of USP19 in hindlimb muscles increased the mass and fiber size in soleus muscle in females but not males. Using Usp19 promoter reporter constructs, a functional half-estrogen response element (hERE) was identified in intron 1 of Usp19. ERα bound to hERE in an E2-dependent manner in C2C12 myoblasts and in soleus muscle in ovariectomized (OVX) female mice. Furthermore, under normal physiological conditions, ERα bound to hERE in soleus muscle only in females. In contrast, administration of E2 resulted in increased Usp19 mRNA expression, decreased muscle mass, and recruitment of ERα to hERE in soleus muscle in males. Knockdown of ERα in hindlimb muscles decreased Usp19 mRNA expression and increased the mass of soleus muscle only in females. Knockdown of USP19 resulted in increased levels of ubiquitin conjugates in soleus muscle in females. OVX increased the levels of ubiquitin conjugates and administration of E2 decreased OVX-induced levels of ubiquitin conjugates. These results demonstrate that in soleus muscle in young female mice under physiological conditions, E2 upregulates USP19 expression through ERα and consequently leads to decreases in ubiquitin conjugates and muscle mass.
A Dynamic Mobile DNA Family in the Yeast Mitochondrial Genome
Authors: Wu Baojun , Hao Weilong
Published: April 2015

Transposable elements (TEs) are an important factor shaping eukaryotic genomes. Although a significant body of research has been conducted on the abundance of TEs in nuclear genomes, TEs in mitochondrial genomes remain elusive. In this study, we successfully assembled 28 complete yeast mitochondrial genomes and took advantage of the power of population genomics to determine mobile DNAs and their propensity. We have observed compelling evidence of GC clusters propagating within the mitochondrial genome and being horizontally transferred between species. These mitochondrial TEs experience rapid diversification by nucleotide substitution and, more importantly, undergo dynamic merger and shuffling to form new TEs. Given the hyper mobile and transformable nature of mitochondrial TEs, our findings open the door to a deeper understanding of eukaryotic mitochondrial genome evolution and the origin of nonautonomous TEs.
TARHANDS: A MESSY MANIFESTO
Authors: Cariou Warren
Published: April 2015

This essay attempts to make visible the physical reality of the Athabasca oil sands mining developments in Canada, a reality that has been occluded by corporate and governmental disinformation as well as by citizens’ unwillingness to face the consequences of their actions and their inaction.  By presenting photographs of oil sands mining operations interspersed with brief ironic narratives, aphorisms and poems, the essay creates a collage of disjunctive responses to the contemporary situation in the Canadian petro-state.  Given that this situation is one of national self-deception, denial and fundamentally irrational behavior, the paper sets aside any attempt to make reasoned arguments about conservation or regulation, and instead embraces irrationality as the last possible mode of engagement with a contemporary public that will no longer listen to reason.  In tone and structure the essay echoes F. T. Marinetti’s 1909 “Futurist Manifesto,” but it is very different in its intent, mapping a way toward a different kind of future than the technologized and hyper-individualistic one that Marinetti espoused.  By moving into the realm of the irrational and engaging with Canadian petroculture as an expression of a kind of national unconscious, the essay attempts to reveal some of the psychological structures that prevent Canadians from seeing the dirt that is on their hands.
OIL IMAG(E)INARIES: CRITICAL REALISM AND THE OIL SANDS
Authors: Szeman Imre , Whiteman Maria
Published: April 2015

This photo-essay constitutes an initial attempt to map out the forces and dynamics of capital at work in Fort McMurray, Alberta—a primary site of global oil extraction and a space that is now at the heart of the contemporary Canadian economy; it does so through the practice of ‘critical realism’ advocated by artist and critic Allan Sekula. The essay consists of three parts. In the first part, we describe the characteristics of Sekula’s critical realism, focusing in particular on his employment of this aesthetico-political practice in his book Fish Story (1991), an attempt to challenge dominant narratives about globalization as immaterial and unrepresentable by means of a focus on the transportation of goods by container ships. In the second part, we explore the challenge of representing another all-too frequently hidden material dimension of globalization: our continued dependence on oil and its by-products. Instead of focusing directly and literally on the site of oil extraction, the photo-essay we produce in the third part probes the effects of oil on life and labour in Fort McMurray. We do so in order to better understand the city’s specific socio-political challenges and to grasp the broader implications of oil for contemporary politics, culture and representation.
STEALING OR STEELING THE IMAGE? THE FAILED BRANDING OF THE GUERRILLERO HEROICO IMAGE OF CHE GUEVARA
Authors: Cambre Maria-Carolina
Published: April 2015

This article traces the ongoing tension between those who would characterize Alberto Korda’s famous image of Che Guevara, The Guerrillero Heroico, as a brand, trademark or logo, and those who insist it is a political/cultural icon and non-commercial and that these categories are mutually exclusive. The question of whether the image has been emptied of political content, and the debate around the copyrighting of an image considered by many to be in the public domain and a cultural icon are explored. The long-lasting struggle over the meanings and collective memories associated with this image indicate the possibility that both processes of commodification and radicalization of the image of Che Guevara can coexist. Using the literature on consumer research to engage definitions of branding as a commercially geared venture, this article teases out the problematics of different uses of the photograph and its derivatives, and highlights ambiguities around the notions of creation and authorship. After examining this image’s role within Cuba, Cuban use outside of Cuba, and its commercial and non-commercial uses by non-Cubans, I conclude that attempts at branding products with this particular image fail, and therefore its copyrighting is irrelevant.
“MIRRORING TERROR”: THE IMPACT OF 9/11 ON HOLLYWOOD CINEMA
Authors: Riegler Thomas
Published: April 2015

By drawing upon Siegfried Kracauer’s concept of cinema as a “mirror” of society, this article explores the impact of the “terror years” since 2001 on US cinema. Hollywood was the main cultural apparatus for coping with 9/11, which had left Americans struggling in the “desert of the real” (Žižek). Visual content simplifies traumatic events like the terrorist attacks for audiences—often expressing them in simple Manichean black and white terms and thereby offering moral guidance, unity, and a sense of destiny. Hollywood’s response to 9/11 included all these different aspects: It appealed to an “unbroken” spirit, strove to reassert the symbolic coordinates of the prevailing American reality, and mobilised for a response to new challenges. With time passing, Hollywood also incorporated the mounting doubts and dissent associated with this process. As the review of relating movies of the “terror years” demonstrates, the American film industry has examined, processed, and interpreted the meaning of the terrorist attacks in great variety: Ranging from merely atmospheric references to re-enactments, from pro-war propaganda to critical self-inquiry.
Solar-Generated Steam for Oil Recovery: Process Integration Options, Net Energy Fraction, and Carbon Market Impacts
Authors: O'Donnell J. , Heisler M.A. , Chandra M.
Published: April 2015

Objectives/Scope

Review of the process integration alternatives for interconnecting solar steam generators into existing steam facilities, and resulting facilities costs, energy contribution (solar fraction), and net CO2 credits generated.

Methods, Procedures, Process

Siting and land footprints were chosen for several thermal recovery projects. Three integration options were studied: water preheating, constant-rate steam with balanced boiler turndown, and variable-rate steam distribution. Solar collector arrays were laid out and hourly energy production modeled. Aspen Hysys studies were carried out and line sizes, pressure drops, and facilities costs were estimated for the full path to the wellhead. Annual total contributions to steam injected (solar fraction) were evaluated.

Results, Observations, Conclusions

Solar preheating of boiler feedwater required the least changes to existing facilities, and was economical especially at fields with lower temperature boiler feedwater; solar fraction was limited in most cases to under 6%. Constant-rate steam injection increased practical solar fraction to above 15%, while requiring changes only to the steam generator setting. Variable-rate steam injection involved facilities changes to wellhead rate control devices but allowed over 50% solar fraction with economical facilities costs.

Novel/Additive Information

In March 2014, the California Air Resources Board released an estimate that if 30% of California oilfield steam were solar, 3.7 million tons/yr of credits would be generated in the Cap & Trade program, and an additional 4.3 million tons/yr in the Low Carbon Fuel Standard program. Facilities and land constraints associated with achieving that target are reviewed.
Minimizing NPT: The Elimination of Cement Plug Failures in the Western US
Authors: Hudson M. , Sones E.A. , Eulberg J.T.
Published: April 2015

Industry-wide cement plug failures account for more than 1,000 hours of lost time and USD 20 million in nonproductive time (NPT) costs each year, including individual failures responsible for up to 350 hours of lost time and USD 3 million in NPT costs. These failures include unset or soft cement that cannot meet the plug requirements, top of cement not at the designed depth, loss of cement plug, and stuck pipe. The causes of cement plug failures include incorrect temperatures, slurry contamination, cement falling in the wellbore, and inadequate displacement methods.

Best practices applied during a new process include temperature mapping of major fields, evaluation of the plug base, implementation of mechanical fluid separation, optimization of balancing fluids while pulling out of hole, and mathematical modeling of fluid contamination. The peer-review process for the design answers four simple questions: Is the design documentation complete and accurate? Does the design meet a clearly defined client objective? Does the design adhere to plug cementing best practices? Is the cementing crew prepared to properly execute the job?

In 2012, nine western US cement plug failures resulted in over 200 hours of lost time and USD 500,000 in NPT costs. The lack of technical design criteria and accountability process demonstrated the need for improvement. In response, a regional investigation and quality initiative were launched. The investigation found regional failures related to cement contamination, incorrect displacement, poor slurry design, and incorrect well data. As a result, a specific process for handling all plug cement jobs was implemented. This process included adherence to a number of plug cementing best practices and a peer-review of all plug cement designs.

Approximately 500 cement plug jobs have been executed within the last 27 months in the western US region since the implementation of the plug cementing process. In this time, there have been no plug failures, no NPT, and no rig costs from failed cement plug operations.
Impact of Stimulation Net to Gross Ratio on Hydraulic Fracture Deliverability in Unconventional Resources
Authors: Ganpule S. , Waters G. , Al-Jalal Z.
Published: April 2015

We propose a novel concept relating to using net-to-gross (NTG) ratios in characterizing hydraulic fracture deliverability. Current NTG considerations applied in unconventional resources are primarily petrophysics-based. However, the variability of in-situ stress and material properties in the vertical direction greatly influence placement and vertical connectivity of a given hydraulic fracture. Hence, the areas of low connectivity within the created fracture system, such as pinch offs, can impact production performance and thus become a key asset development driver that ultimately influences project economics. Therefore, characterizing pinch offs in a created fracture network becomes a necessity. Such characterization can be accomplished by splitting NTG into two components—petrophysical (NTG-P) and stimulation (NTG-S). The focus of this work is the NTG-S.

The proposed NTG-S is currently based on hydraulic fracture and production models coupled with calibration data from offset wells. For a given stress and material property profile, hydraulic fracture geometries are estimated using a fracture simulator with multiple calibration points. The post fracture closure width profile from the calibrated fracture model indicates possible pinch points along the created fracture height. The calibrated fracture geometry is then integrated into a production model, where the impact of the pinch points on well performance is simulated while honoring the actual production data. High-resolution stress logs and fullbore cores can help to address uncertainty in location and severity of pinch points and aid in reducing the non-uniqueness that is inherent to production models.

NTG-S influences the productive fracture height, which in turn impacts the drainage volume and drainage area around a well. Subsequently, the drainage area affects well spacing and completion design considerations. For a given productive fracture surface area, overestimating NTG-S (assuming a large productive fracture height) can result in an assumed short drainage length, leading operators to laterally place offset wells closer than needed. Conversely, underestimating NTG-S can cause operators to space offset wells too far apart, resulting in lower recoveries. Consequently, in very thick unconventional reservoirs, stacked horizontal wells may be more appropriate. Accounting for NTG-S allows optimizing lateral landing points to ensure optimum drainage configuration is achieved.
Robust Spacer System for Water and Oil based Mud
Authors: Pernites Roderick , Khammar Merouane , Santra Ashok
Published: April 2015

Cementing is an extremely important part in completion that is mainly dependent on successful wellbore clean-up of drilling fluid or mud. As a unique strategy, a cleaning fluid (or series of fluids) called as spacer (or spacer train) is first deployed to displace the mud and clean the wellbore prior to pumping the cement slurry. However, efficient mud clean-up is highly difficult and has been a perennial challenge. This paper reports a new robust cement spacer that can be used for efficient cleaning of water-based and oil-based drilling fluids and enables metal casing water-wetting. Rheological modelling has been carried out to determine the best suited model as well as to demonstrate the factors that influence effective fluid flow in the annulus. The designed spacer also demonstrates high compatibility with the mud and the cement, and it can be designed at varying densities by simply adjusting the ratio of the base materials in the formulation. The addition of the new advanced surfactant solution enables the spacer oil based mud (OBM) compatible.

This paper also introduces a cost effective and new improved laboratory approach of directly evaluating the relative OBM cleaning efficacy of surfactants in spacers on metal casing and formation, which is a novelty of this work that can be easily adopted in any field laboratory. Briefly, the method involves staining of the OBM with a very distinct red-colored organic dye, which permits better visibility of the OBM if it is or not efficiently removed during the clean-up procedure demonstrated in a conventional rheometer sleeve test. This innovative technique provides an advantage of clearly determining if a monolayer of oil still remains on the surface even after spacer washing.
Retrieval of Misfired Perforating Systems from Shallow Well Operations: Potential Thermal Cookoff Hazard
Authors: Davidson Justine M. , Barker James M.
Published: April 2015

During perforating operations, the vast majority of perforating runs are executed without issue. It is possible, however, for misfires to occur. A special case of misfire can result when guns partially fire, leaving an unknown state of the remaining ballistic train. This type of misfire warrants deeper consideration, particularly for shallow well perforating on wireline. This paper examines how a partially fired gun can create a potentially hazardous situation based on the mechanism of delayed thermal cookoff.

A relevant scenario for wireline perforating operations is used to simulate the delayed cookoff process. It begins with the initiation of a portion of the explosive train and the resulting release of heat. This raises the internal temperature and pressure of the gun, further accelerating thermal decomposition of the remaining explosive components. This continues to add heat and pressure to the system, potentially creating a situation of runaway reaction. The outcome of the process during gun retrieval can range from quiet decomposition to gun burst, depending on the starting conditions and reaction kinetics.

Decomposition calculations and the accompanying pressure response are made using multi-step time iterations that show the progression of the decomposition process over time. Several factors can affect the decomposition reaction, such as downhole temperature, the amount of explosives that initially react, explosive type, and the free air volume inside the gun. For the case of runaway reaction, which can result in violent gun burst, proper job planning must be considered beforehand to help prevent damage to equipment and injury to personnel, should the event occur upon retrieval of guns to surface. To help mitigate risk, it is critical to advantageously use time and cooler temperatures in these situations. Moreover, to reduce uncertainty, the benefits of taking quantitative surface measurements are discussed.

This paper describes the mechanism for delayed thermal cookoff and its potentially hazardous impact when retrieving misfired guns. The paper additionally shows how field personnel can determine if it is occurring at surface. A recommended procedure for retrieving these guns is suggested, which is wholly consistent with OSHA Process Safety Management.
Denoising of Seismic Data Using Curvelet Transformation: The Effect of on the Content of the Data
Authors: Dashtian Hassan , Sahimi Muhammad
Published: April 2015

Seismic data usually contain stochastic noise, such as the ground roll (GR), a coherent noise. The noise masks the useful content of the data, such as geologic information that seismic records contain. Removal of the noise has always been a problem of fundamental importance. There are already several methods for removing the noise from seismic images, almost all of which have the drawback that they degrade both the noisy and the “unpolluted” regions in seismic images. In addition, seismic data typically contain long-range correlations, characterized by a Hurst exponent H. In this study we propose a novel method for denoising the entire seismic image. The method is based on the curvelet transform (CT), a multiscale transformation with strong directional characters that provides an optimal representation of objects with discontinuities along their edges. We also study the effect of denoising on the Hurst exponent and, hence the long-range correlations that the images contains. Then, to reduce, or eliminate altogether, the impact of denoising on the correlations in the seismic data contain, we propose a denoising method based on the CT and a coherence index (CI) that we introduce in this paper. As an example, we apply the method to seismic images that are contaminated with the GR noise. First, the CI, representing a measure of the amount of energy contained in the most coherent modes of Karhunen-Loeve transform for any given segment of the data, is computed. The contaminated region of the data is then identified as the region with the maximum CI. After demarcating the contaminated segment, the CT is used to eliminate the noise. The method removes the noise with negligible distortion of the data's non-contaminated region. Its computations are also significantly more efficient than those of the previous methods. The use of the method is demonstrated by its application to synthetic, as well as actual seismic data for hydrocarbon reservoirs.
Applying Machine Learning Techniques to Interpret Flow Rate, Pressure and Temperature Data From Permanent Downhole Gauges
Authors: Tian Chuan , Horne Roland N.
Published: April 2015

Permanent downhole gauges (PDGs) provide a continuous record of pressure, temperature, and sometimes flow rate during well production. The continuous record provides us rich information about the reservoir and makes PDG data a valuable source for reservoir analysis. It has been shown in previous work that the convolution kernel based data mining approach is a promising tool to interpret flow rate and pressure data from PDGs. The convolution kernel method denoises and deconvolves the pressure signal successfully without explicit breakpoint detection. However, the bottlenecks of computational efficiency and incomplete recovery of reservoir behaviors limit the application of the method to interpret real PDG data.

In this paper, three different machine learning techniques were applied to flow rate - pressure interpretation. We formulated the problem into a linear regression on parameters that connect the nonlinear flow rate features with pressure targets. The linear process leads to a closed form solution, which speeds up the computation dramatically. Linear regression was shown to have the same learning quality as the convolution kernel method, and outperforms it with much less computational effort.

Kernel ridge regression was applied to address the issue of incomplete recovery of reservoir behaviors. Kernel ridge regression utilizes the expanded features given by the kernel function to capture the more detailed reservoir behaviors, while controlling the prediction error using ridge regression. It was shown that kernel ridge regression recovers the full reservoir behaviors successfully, e.g. wellbore storage effect, skin effect, infinite-acting radial flow and boundary effect.

Some potential uses of temperature data from PDGs are also discussed in this paper. Machine learning was shown to be able to model temperature and pressure data recorded by PDGs, even if the actual physical model is complex. This originates from the fact that by using features as an approximation, machine learning does not require perfect knowledge of the physical model. The modeling of pressure using temperature data was extended to two promising applications: pressure history reconstruction using temperature data, and the cointerpretation of temperature and pressure data when flow rate data are not available.
Nano-Proppants for Fracture Conductivity Improvement and Fluid Loss Reduction
Authors: Bose Charles C , Gul Awais , Fairchild Brian , Jones Teddy , Barati Reza
Published: April 2015

Hydraulic fracturing has been proved as a successful technology to increase productivity of ultra-tight shale oil and shale gas reservoirs. Although higher concentrations of polymer were traditionally used for conventional fractures, “linear gels”, “waterfracs”, “slick-water” and ”hybrid” fluids have been typically applied for tight shale plays as we produce from formations with lower permeability and higher brittleness. Fracturing jobs in tight shale plays tend to generate or extend a network of fractures while a bi-wing fracture was typically generated in conventional reservoirs. This network of fractures includes a large network of micro-fractures opened during the injection of fracturing fluids. Small fractures tend to close under closure stress unless a nano-sized proppant with significant stress resistance is injected to keep these micro-fractures opened. Although very high conductivity is not required for very low permeability formations, an open fracture or micro-fracture performs better than a collapsed fracture.

Proppants with different mesh sizes of 20/40, 30/50, 40/70, 70/140 and 80/200 with grain diameters ranging from 0.033 inch (0.8382 mm) to 0.0041 inch (104.14 μm) have been used during hydraulic fracturing of tight shale formations. These proppants are large enough to create conductivity in the larger generated or existing fractures but not small enough to penetrate into the existing or generated micro-fractures. This will cause the closure of micro-fractures at the end of a fracturing job thus reduction in the length and conductivity of the complex fracture network. This reduction in the fracture network extension will reduce production from tight shale formations.

The objective of this work is to investigate size, nano-hardness, reduced elastic modulus, fluid loss prevention capabilities as well as their induced fracture conductivity by nano-proppants from a currently known waste product.

Transmission Electron Microscope (TEM) images showed that nano-proppants had particle sizes varying from 100 nm to 1 μm. Particles showed hardness and reduced elastic moduli of 1.3 GPa and 20 GPa, respectively. These properties show potential for these nanoparticles to be used as proppants to keep fractures open under stress.

Fluid loss tests were conducted using 1% (w/w) concentrations of nanoparticles mixed with 2% (w/w) of KCl, cross-linked guar solutions, and cross-linked guar solutions mixed with 1 % concentration of nanoparticles and significant fluid loss reduction was observed for one of several types of nanoparticles. These nanoparticles generated significant conductivity when used as proppants in an API fracture conductivity test. Fracture permeability values of 27-33 mD were generated using these nano-proppants.

Use of nanoparticles prior to the placement of larger proppants is recommended in order to prevent fluid loss into the formation, and also increase the conductivity of the fissures and micro-sized fractures.
Shifts in the Fundamental Frequency of a Fluid Conveying Pipe Immersed in a Viscous Fluid for use in the Optimization of an Energy Harvesting System to be Deployed in a Producing Hydrocarbon Well
Authors: Kjolsing E. , Todd M.
Published: April 2015

Novel methods for harvesting energy in down hole applications are desired. Specifically, it is hoped that sufficient power can be generated near a hydrocarbon reservoir to operate commercially available well monitoring equipment. Vibration based harvesters are the most likely systems to be developed. The efficiency of such harvesters is highly dependent on the natural frequency of the structural system. To optimize the harvester design, the dynamic properties of the down hole system must be characterized.

This paper presents the results of an analytical frequency study undertaken to identify the role axial force effects, annulus fluid geometry, and annulus fluid properties have on the first natural frequency of a production string as the conveyed fluid velocity was varied. The system was modeled using an Euler-Bernoulli formulation and includes a hydrodynamic forcing function to account for annulus fluid effects. The problem was solved in the frequency domain using the spectral element method, which conveniently provides natural frequency information.

The results of the study are in-line with previously published studies on analogous systems. It was found that the well annulus geometry, annulus fluid density, and annulus fluid viscosity have a strong role in determining the behavior of the system. Additionally, the axial force, added mass, and viscous effects were found to shift the natural frequency of the system while only axial force and viscous effects cause a shift in the fluid velocity at which bifurcation occurs. These findings, along with the method outlined in this paper, provide a useful tool in the characterization of hydrocarbon producing wells which is a first step towards developing an energy harvesting system.

Although the problem of determining the dynamics of a fluid conveying pipe immersed in a viscous fluid has been approached using a shell formulation in the past, to the authors knowledge this is the first time the problem has been solved with a beam formulation.

Approved for publication, LA-UR-15-21089. Copyright for this paper have been transferred to SPE.
Reservoir Waterflooding System Identification and Model Validation with Injection/Production Rate Fluctuations
Authors: Rezapour A. , Ortega A. , Ershaghi I.
Published: April 2015

Describing injector-producer relationships in waterflooding with a Linear Time Invariant (LTI) model is mainly based on black box modeling techniques, where the model parameters do not necessarily have physical interpretation. Therefore, the question is whether one can be certain about the range of the estimated parameters and their validity when they cannot be verified with measurements. In this paper, we will show the connection between the conditions on the training data and the reliability of the predictions of the mathematical models. Our results show that if the injection rates (before and after water break through) have variations at relatively low frequencies and without high amplitude, then the identified models with well-known model parameterization, such as capacitance model, have accurate predictions. The observations in this research imply that for obtaining reliable models; (i) one must find the appropriate amplitude and frequency for injection rate fluctuations, (ii) while keeping the reservoir condition and its working point in linear (or close to linear) regime. Otherwise, the model identification becomes unreliable, since the models that are used in practice tend to be LTI.
Improved Proxy For History Matching Using Proxy-for-data Approach And Reduced Order Modeling
Authors: He Jincong , Xie Jiang , Wen Xian-Huan , Chen Wen
Published: April 2015

Response surface proxies are commonly used in history matching process to approximate the functional relationship between the input parameters and the aggregated mismatch. The quality of the proxy (accuracy in prediction) degrades as the nonlinearity of the response surface increases. However, commonly-used definitions of aggregated mismatch, such as root mean squared error (RMSE) or mean absolute error (MAE), are highly nonlinear. As a result, the quality of the proxy for aggregated mismatch can be unsatisfying in many cases.

In this work we propose the proxy-for-data approach, in which one proxy is built for each observation data point and then the data values predicted by those proxies are used to calculate the aggregated mismatch. Because proxies are constructed for the data themselves rather than for the aggregated mismatch, the nonlinearity of the aggregated mismatch definition will not affect the quality of the proxy. It is shown in multiple test cases that the new approach consistently improves proxy quality for different types of proxies and different aggregated mismatch definitions. For cases with large amount of observation data points, we also show that the use of reduced-order modeling can efficiently reduce the number of proxies needed and achieve similar improvement. The new approach is successfully applied to both synthetic and field examples and both examples show improved proxy quality.
An Analytical Comparison of Wellbore Deviation and its Effects on Proper Centralization in the Bakken
Authors: Fry Dominik , Pruett Bradley
Published: April 2015

The effects of centralization on the quality of a cement job should not be underestimated. Poor centralization promotes channeling and poor removal of drilling mud/filter cake. Even the best designed cement might not perform if mud is left in the hole with cement on just one side of the wellbore. Computer simulations are effective tools in predicting ideal centralizer placement, but placement is frequently based solely off planned wellbore data. The general well plan in North Dakota is to drill vertically until kicking off to drill the horizontal section through the Bakken formation. In theory, a casing string will stay centralized without any centralizers in a truly vertical wellbore. This has led to the use of only a sparse number of centralizers, even though many cement bond logs can show poor bonding far below the desired top of cement. In cases of poor isolation the state regulatory agency might require an additional string to be run for the stimulation procedure, as well as cathodic protection on the casing.

A sampling of wells spaced throughout the Bakken was put into a deviation analysis. All wells were planned vertical until the desired kickoff point. These wells were analyzed for trends in deviation, dog leg severity, and required centralizer spacing to achieve the desired standoff. Sections of the wellbores were identified with higher tendencies towards deviation from the desired well path. The average required centralization was determined and rules were generated based off dog leg severity and deviation. These rules were used to create an optimized centralization schedule, which was tested against the original wellbores.

The results clearly show that the planned vertical section is rarely vertical. While the deviation from plan varies widely, even small deviations impact centralization significantly. This is likely one of the first analysis done on multiple wells to analyze the influence of prejob planning on cementing in the Bakken. Because of the thorough analysis on past operations, a more robust design can be proposed for real-world conditions in the future.
Decision-Useful Asset Measurement from a Business Valuation Perspective
Authors: Botosan Christine A. , Huffman Adrienna A.
Published: April 2015

SYNOPSIS

This article proposes an approach to asset measurement rooted in business valuation theory and practice. In the context of a business valuation, investors' information needs and the asset measurement investors find useful vary with the manner in which the assets are expected to realize value for the firm. After reviewing arguments made in economic and accounting theory, accounting research, accounting standards, and practitioner and business valuation literature, we conclude that for in-exchange assets, investors need to determine the value expected to be realized in exchange. Exit price in a hypothetical market exchange (i.e., fair value) less expected costs to sell provides investors with decision-useful information in this regard; replacement cost and historical cost do not. For in-use assets investors require information useful in forecasting cash flows generated by using such assets in combination. Based on arguments and data presented in the aforementioned literature, we conclude that historical cost generally provides investors with decision-useful information for forecasting purposes; fair value does not. In addition, replacement cost can provide decision-useful information provided holding gains and losses are separately disclosed, but its decision-usefulness can be constrained by verifiability concerns.
Preserved Insulin Secretory Capacity and Weight Loss Are the Predominant Predictors of Glycemic Control in Patients With Type 2 Diabetes Randomized to Roux-en-Y Gastric Bypass
Authors: Nguyen Kim T. , Billington Charles J. , Vella Adrian , Wang Qi , Ahmed Leaque , Bantle John P. , Bessler Marc , Connett John E. , Inabnet William B. , Thomas Avis , Ikramuddin Sayeed , Korner Judith
Published: April 2015

Improvement in type 2 diabetes after Roux-en-Y gastric bypass (RYGB) has been attributed partly to weight loss, but mechanisms beyond weight loss remain unclear. We performed an ancillary study to the Diabetes Surgery Study to assess changes in incretins, insulin sensitivity, and secretion 1 year after randomization to lifestyle modification and intensive medical management (LS/IMM) alone (n = 34) or in conjunction with RYGB (n = 34). The RYGB group lost more weight and had greater improvement in HbA1c. Fasting glucose was lower after RYGB than after LS/IMM, although the glucose area under the curve decreased comparably for both groups. Insulin sensitivity increased in both groups. Insulin secretion was unchanged after LS/IMM but decreased after RYGB, except for a rapid increase during the first 30 min after meal ingestion. Glucagon-like peptide 1 (GLP-1) was substantially increased after RYGB, while gastric inhibitory polypeptide and glucagon decreased. Lower HbA1c was most strongly correlated with the percentage of weight loss for both groups. At baseline, a greater C-peptide index and 90-min postprandial C-peptide level were predictive of lower HbA1c at 1 year after RYGB. β-Cell glucose sensitivity, which improved only after RYGB, and improved disposition index were associated with lower HbA1c in both groups, independent of weight loss. Weight loss and preserved β-cell function both predominantly determine the greatest glycemic benefit after RYGB.
Young, Old, and Weathered Carbon-Part 1: Using Radiocarbon and Stable Isotopes to Identify Carbon Sources in an Alkaline, Humic Lake
Authors: Keaveney Evelyn M , Reimer Paula J , Foy Robert H
Published: April 2015

This article presents a case study of Lower Lough Erne, a humic, alkaline lake in northwest Ireland, and uses the radiocarbon method to determine the source and age of carbon to establish whether terrestrial carbon is utilized by heterotrophic organisms or buried in sediment. Stepped combustion was used to estimate the degree of the burial of terrestrial carbon in surface sediment. Δ14C, δ13C, and δ15N values were measured for phytoplankton, dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and particulate organic carbon (POC). Δ14C values were used to indicate the presence of different sources of carbon, including bedrock-derived inorganic carbon, “modern,” “recent,” “subsurface,” and “subfossil” terrestrial carbon in the lake. The use of14Cin conjunction with novel methods (e.g. stepped combustion) allows the determination of the pathway of terrestrial carbon in the system, which has implications for regional and global carbon cycling.
Vice-presidential behavior in a disability crisis: The case of Thomas R. Marshall
Authors: Goldstein Joel K.
Published: April 2015

Vice President Thomas R. Marshall has been criticized for not acting more aggressively to exercise presidential powers and duties after President Woodrow Wilson suffered a stroke in October 1919 which compromised his ability to discharge his office for much of the remainder of his term. Yet Marshall faced formidable constraints in the constitutional, political, institutional, and factual context in which he operated. This paper examines these constraints on Marshall's political behavior. His conduct becomes understandable when viewed in the context of those inhibiting factors. The paper also considers the impact of the presidential inability provisions of the subsequently ratified Twenty-Fifth Amendment which renowned Wilson scholar Arthur Link suggested would have made no difference. While questioning the practicality of that counter-factual, the paper argues that the Amendment would have been helpful but suggests that a Wilson-like situation, if one could be imagined in modern times, could present a relatively taxing challenge to our constitutional system.
Optimizing plant density of promising Rice genotypes in northwest Bangladesh
Authors: Karmakar B , Sarkar MA R , Ali MA , Haefele SM
Published: April 2015

A study was conducted at the Bangladesh Rice Research Institute, regional station farm, Rajshahi, Bangladesh, during 2010 and 2011 wet seasons to determine the effect of plant density on the performance of different genotypes. Three plant densities (20- × 15-, 20- × 20- and 25- × 15-cm spacing) and six genotypes (BRRI dhan56, BRRI dhan57, IR83377-B-B-93-3, IRRI 123, IR83381-B-B-6-1 and Binadhan-7) were tested in a strip-plot design with three replications, placing planting densities in the vertical plots and genotypes in the horizontal plots. Planting density × genotype produced significant effect on grain yield in 2011 but not in 2010. BRRI dhan56, BRRI dhan57 and IR83381-B-B-6-1 produced the highest grain yield in 20- × 15-cm spacing, while the other genotypes (IR83377-B-B-93-3, IRRI 123 and Binadhan-7) produced the higher yields in 25- × 15- or 20- × 20-cm spacing. In both years, genotypes had significant effects on grain yield, all yield components, growth duration, plant height, tillers hill-1 and tillers m-2, but not on straw and biological yield. Among the genotypes, IR83377-B-B-93-3 gave the highest mean grain yield (5.11 t ha-1) followed by IRRI 123 (4.97 t ha-1). The lowest mean yield (4.04 t ha-1) was found in BRRI dhan57 followed by IR83381-B-B-6-1 (4.14 t ha-1). Planting density had significant effects on grain yield, panicles hill-1, panicles m-2, tillers hill-1 and tillers m-2, and closer spacing reduced the number of days to flowering and maturity. Short duration rice genotypes achieved higher grain yields in closer spacing while longer duration genotypes produced higher grain yields in wider spacing. Results of this investigation suggest that the optimal plant density is dependent on varietal characteristics, and that current fixed planting densities used in many rice cropping systems are probably not adequate.Bangladesh Rice j. 2014, 18(1&2): 1-7