bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reservoir Modeling for Flow Simulation by Use of Surfaces, Adaptive Unstructured Meshes, and an Overlapping-Control-Volume Finite-Element Method
Authors: Jackson M.D.. D. , Percival J.R.. R. , Mostaghimi P.. , Tollit B.S.. S. , Pavlidis D.. , Pain C.C.. C. , Gomes J.L.M.A.. L.M.A. , El-Sheikh A.H.. H. , Salinas P.. , Muggeridge A.H.. H. , Blunt M.J.. J. 
Published: May 2015

SummaryWe present new approaches to reservoir modeling and flow simulation that dispose of the pillar-grid concept that has persisted since reservoir simulation began. This results in significant improvements to the representation of multiscale geologic heterogeneity and the prediction of flow through that heterogeneity. The research builds on more than 20 years of development of innovative numerical methods in geophysical fluid mechanics, refined and modified to deal with the unique challenges associated with reservoir simulation.Geologic heterogeneities, whether structural, stratigraphic, sedimentologic, or diagenetic in origin, are represented as discrete volumes bounded by surfaces, without reference to a predefined grid. Petrophysical properties are uniform within the geologically defined rock volumes, rather than within grid cells. The resulting model is discretized for flow simulation by use of an unstructured, tetrahedral mesh that honors the architecture of the surfaces. This approach allows heterogeneity over multiple length-scales to be explicitly captured by use of fewer cells than conventional corner-point or unstructured grids.Multiphase flow is simulated by use of a novel mixed finite-element formulation centered on a new family of tetrahedral element types, PN(DG)–PN+1, which has a discontinuous Nth-order polynomial representation for velocity and a continuous (order N +1) representation for pressure. This method exactly represents Darcy-force balances on unstructured meshes and thus accurately calculates pressure, velocity, and saturation fields throughout the domain. Computational costs are reduced through dynamic adaptive-mesh optimization and efficient parallelization. Within each rock volume, the mesh coarsens and refines to capture key flow processes during a simulation, and also preserves the surface-based representation of geologic heterogeneity. Computational effort is thus focused on regions of the model where it is most required.After validating the approach against a set of benchmark problems, we demonstrate its capabilities by use of a number of test models that capture aspects of geologic heterogeneity that are difficult or impossible to simulate conventionally, without introducing unacceptably large numbers of cells or highly nonorthogonal grids with associated numerical errors. Our approach preserves key flow features associated with realistic geologic features that are typically lost. The approach may also be used to capture near-wellbore flow features such as coning, changes in surface geometry across multiple stochastic realizations, and, in future applications, geomechanical models with fracture propagation, opening, and closing.
Fitting Foam-Simulation-Model Parameters to Data: II. Surfactant-Alternating-Gas Foam Applications
Authors: Rossen W. R. , Boeije C. S. 
Published: May 2015

SummaryFoam improves sweep in miscible and immiscible gas-injection enhanced-oil-recovery processes. Surfactant-alternating-gas (SAG) foam processes offer many advantages over coinjection of foam for both operational and sweep-efficiency reasons. The success of a foam SAG process depends on foam behavior at very low injected-water fraction (high foam quality). This means that fitting data to a typical scan of foam behavior as a function of foam quality can miss conditions essential to the success of an SAG process. The result can be inaccurate scaleup of results to field application.We illustrate how to fit foam-model parameters to steady-state foam data for application to injection of a gas slug in an SAG foam process. Dynamic SAG corefloods can be unreliable for several reasons. These include failure to reach local steady state (because of slow foam generation), the increased effect of dispersion at the core scale, and the capillary end effect. For current foam models, the behavior of foam in SAG depends on three parameters: the mobility of full-strength foam, the capillary pressure or water saturation at which foam collapses, and the parameter governing the abruptness of this collapse. We illustrate the fitting of these model parameters to coreflood data, and the challenges that can arise in the fitting process, with the published foam data of Persoff et al. (1991) and Ma et al. (2013). For illustration, we use the foam model in the widely used STARS (Cheng et al. 2000) simulator. Accurate water-saturation data are essential to making a reliable fit to the data. Model fits to a given experiment may result in inaccurate extrapolation to mobility at the wellbore and, therefore, inaccurate predicted injectivity: for instance, a model fit in which foam does not collapse even at extremely large capillary pressure at the wellbore.We show how the insights of fractional-flow theory can guide the model-fitting process and give quick estimates of foam-propagation rate, mobility, and injectivity at the field scale.
Characterizing the Effects of Lean Zones and Shale Distribution in Steam-Assisted-Gravity-Drainage Recovery Performance
Authors: Wang Cui , Leung Juliana Y. 
Published: May 2015

SummaryPerformance of steam-assisted gravity drainage (SAGD) is influenced significantly by the distributions of lean zones and shale barriers, which tend to impede the vertical growth and lateral spread of a steam chamber. Previous literature has partially addressed their effects on SAGD performance; however, a comprehensive and systematic investigation of the heterogeneous distribution (location, continuity, size, saturation, and proportions) of shale barriers and lean zones is still lacking.In this study, numerical simulations are used to model the SAGD process. Capillarity and relative permeability effects, which were ignored in many previous simulation studies, are incorporated to model bypassed oil. Numerous ranking schemes are formulated to analyze various aspects of SAGD performance. A detailed sensitivity analysis is performed by varying the location, continuity, size, proportions, and saturation of these heterogeneous features. Lean zones and shale lenses (imbedded in a region of degraded rock properties) with different sizes and degrees of continuity are placed in areas above the injector, below the producer, or in between the well pair. It is noted that among numerous parameters that influence the ultimate recovery, remaining bypassed oil, chamber advancement, and heat loss, continuity and position of these features in relation to the well pair play a particularly crucial role. Neural network modeling is subsequently used for constructing data-driven models to identify and propose a set of input variables for correlating relevant parameters or measures, which are descriptive of the heterogeneity and properties of the shale barriers and lean zones, to recovery and ranking results.This work provides a guideline for assessing the impacts of reservoir and saturation heterogeneities on SAGD performance. A set of input variables and parameters that have significant impacts on the ensuing recovery response is identified. One can define readily the proposed set of variables from well logs and apply immediately in data-driven models with field data and scaleup analysis of experimental models to assist field-operation design and evaluation. One can also extend the approach presented in this paper to analyze other solvent-assisted SAGD processes.
Fitting Foam-Simulation-Model Parameters to Data: I. Coinjection of Gas and Liquid
Authors: Boeije C. S. , Rossen W. R. 
Published: May 2015

Summary
Cheng et al. (2000) present a simple method to fit foam-simulation parameters without oil to data for pressure gradient as a function of superficial velocities of gas and liquid. The key in this process is the identification of “high-quality” (high gas fraction) and “low-quality” foam regimes. The method is essentially the same for the foam-model parameters in foam models in STARS (Cheng et al. 2000), UTCHEM (Cheng et al. 2000), or ECLIPSE (Schlumberger 2010). Often, however, available data are more limited: pressure gradient for one scan of foam quality at fixed total superficial velocity. We show how to extend this method to the more-limited data set. The transition in regimes occurs at the foam quality with the maximum-pressure gradient. We illustrate the method by fitting parameters to several published data sets.
Our approach is simple and direct. The model fit would be appropriate for an enhanced-oil-recovery process involving foam injection at finite water fraction, but not a surface-alternating-gas foam process involving large slugs of gas and liquid. For the latter process, the model fit should focus on data relevant to that process (i.e., at extremely high foam quality).
The approach assumes an abrupt transition between high- and low-quality-foam regimes (e.g., a large value of epdry in the STARS foam model). If the transition is less abrupt, the parameter values quickly obtained by this method could provide the initial guess for a computer-based least-squares fit of all parameters, including a smaller value of epdry, and a check on the parameters so obtained.
Who's the Fairest of Them All? Evidence from Closed-End Funds
Authors: Lawrence Alastair , Siriviriyakul Subprasiri , Sloan Richard G 
Published: May 2015

ABSTRACT
Prior research examining the ASC 820 fair value hierarchy concludes that Level 3 fair value measurements are significantly less value-relevant than Level 1 and Level 2 fair value measurements. We reevaluate this conclusion using the closed-end fund setting, in which fair value measurements are available for substantially all assets. Contrary to prior research, we find that Level 3 fair values are of similar value relevance to Level 1 and Level 2 fair values. Our findings suggest that the results in previous research are attributable to correlated omitted variable bias arising from the absence of fair value data for most assets.
JEL Classifications: M41; G12; G29.
Data Availability: Data are publicly available from sources identified in the article.
Asymmetric Effects of Regulation FD on Management Earnings Forecasts
Authors: Heflin Frank , Kross William J. , Suk Inho 
Published: May 2015

ABSTRACT
We document that the effect of Regulation Fair Disclosure (FD) on public management earnings forecasts (MFs) is asymmetric. Our results suggest that FD increased managers' use of MFs as a downward-guidance mechanism to help achieve meeting or beating earnings expectations. This effect is more pronounced when existing analyst forecasts are optimistic and when firms had selective disclosure policies pre-FD. We also find that the increased use of MFs as downward guidance leads to post-FD reductions in MF quality (accuracy and informativeness) for the downward guiding MFs that are most likely meet/beat motivated, while quality improves for upward-guiding MFs. Finally, our evidence suggests that results from prior research about FD-induced changes in information environment variables, such as analyst forecast quality and investor trading activities, depend on whether the firm issues MFs and whether those MFs are downward guiding.
Data Availability: All data are available from public databases identified in the paper.
Using Incentives to Overcome the Negative Effects of Faultline Conflict on Individual Effort
Authors: Tian Yu , Tuttle Brad M. , Xu Yin 
Published: May 2015

ABSTRACT
In this study, we investigate the effects of faultline-induced conflict on individual effort and how incentives can be designed to overcome these negative effects. Faultlines are hypothetical dividing lines between group members based on various member attributes that can potentially split the overall group into subgroups. Results from our experiment show that team members are more likely to perceive conflict when they face a faultline-related issue, which, in turn, leads to lower effort by individual team members. Consistent with the theory of cooperation and competition, incentives moderate the effect of conflict on effort, such that team incentives have a greater effect to increase effort than individual incentives when the level of conflict is high, rather than low. Collectively, our findings suggest that competitive team incentives may be an effective tool to overcome the negative effects of faultline conflict in a group.
DISCUSSION OF: Testing Strategy with Multiple Performance Measures: Evidence from a Balanced Scorecard at Store24
Authors: Chen Clara Xiaoling 
Published: May 2015

ABSTRACT
The Campbell, Datar, Kulp, and Narayanan (2015; hereafter, CDKN) study empirically investigates how the quality of a firm's business strategy can be tested and validated using statistical analysis of the firm's internal performance measurement system. Using data from the balanced scorecard of a convenience store chain, their study provides empirical evidence that the company's internal performance measures reveal timely information about problems with the strategy and can help identify where and why the strategy failed. In this brief discussion of the study, I first summarize the major strengths of their study, then discuss my concerns and comments, and finally point out some potential extensions. In summary, CDKN's study is important in that it makes significant contributions to several streams of literature. CDKN have inspired follow-up studies on the use of performance measurement systems to evaluate strategy and the testing of business models, and has opened up exciting opportunities for future research.
DNA Stability Contrasts with Chromosome Variability in Allium Fistulosum Calli
Authors: Mizia Patryk , Kwolek Dagmara , Ilnicki Tomasz 
Published: May 2015

Abstract
RAPD analysis was applied to assess the degree of DNA polymorphism in A. fistulosum calli of high chromosomal instability. Nineteen of 24 randomly selected RAPD primers revealed scorable polymorphism between calli and seeds (reference material). Polymorphic band frequency was 55/237 in seeds and 36/233 in calli; variability on the DNA level was thus lower in calli than in seeds (15.4% vs. 23.2% of band positions). UPGMA analysis of Jaccard's coefficients confirmed the genetic similarity of the analyzed cultures. The most distinctive DNA changes in calli involved coincident loss of original bands or the appearance of novel bands. Seven such changes (4 losses, 3 gains) were observed. Our results suggest that changes on the chromosomal level and on the DNA level occurred independently of each other and that different callus lines underwent similar genetic changes during culture, presumably due to strong selection pressure effected by standard in vitro conditions.
Expression Patterns of Convergently Overlapping Arabidopsis Thaliana Gene Pairs OHP-NDP1 and OHP2-MES14
Authors: Stawski Karol , Banach Mariusz , Goc Anna 
Published: May 2015

Abstract
The function of one-helix proteins (OHPs) in the thylakoid membrane remains poorly understood but may be linked to plant photosystem protection. In Arabidopsis, the 3'UTRs of the genes encoding OHP and OHP2 partially overlap with NDP1 and MES14 respectively. Antisense orientation of genes has the potential to form double-stranded transcript (dsRNA) molecules which can be processed to siRNA and trigger RNA interference (RNAi). Natural siRNAs are induced by abiotic and biotic stresses. We examined whether the expression of the OHP-NDP1 and OHP2-MES14 gene pairs is regulated in this way. Both OHP genes, but neither NDP1 nor MES14, were activated by light in etiolated seedlings, whereas cold and prolonged heat treatment elevated the OHP transcript level. Expression of OHP2 was down-regulated after 2 h of osmotic and heat stress, while salt and osmotic stress increased MES14 transcript levels. No inverse regulation of these overlapping gene pairs was observed, excluding RNAi as a regulatory mechanism in the tested conditions. The presence of alternatively polyadenylat-ed transcripts of the studied genes raises the possibility of another regulatory mechanism of 3'UTR overlap.
Expression Pattern of Arabidopsis Thaliana Pollen- and Embryo-Specific Promoter in Transgenic Tobacco Plants
Authors: Jopcik Martin , Matusikova Ildiko , Moravcikova Jana , Libantova Jana 
Published: May 2015

Abstract
Current biotechnology research is focused on tissue-specific expression of genes of interest in plants. Promoters with specific spatial and temporal expression profiles in targeted organisms are in wide use for this. This study investigated whether the Arabidopsis thaliana seed- and pollen-specific promoter MXL maintains its specificity in transgenic tobacco plants. Histochemical analysis revealed that the MXL fusion promoter drives slightly different GUS expression in that heterologous organism. GUS staining was clearly detected in the bicellular stage of pollen development and later in germinating tobacco pollen grains. Unlike in A. thaliana, where the MXL promoter is active during the whole period of embryo development, in tobacco its activity was restricted to a short temporal and spatial window from late-heart to mid-torpedo stages, mainly in the apical part of the developing embryo. These results point to the need to test the expression profiles of heterologous promoters in targeted species before they are used in particular biotechnological programs.
Plant Regeneration Via Organogenesis and Somatic Embryogenesis in Verbascum Sinuatum L.
Authors: Karamian Roya , Ghasemlou Fatemeh 
Published: May 2015

Abstract
The genus Verbascum L. belongs to the family Scrophulariaceae and its members are used as medicinal herbs in traditional medicines worldwide. In this study we achieved plant regeneration in Verbascum sinuatum L. via organogenesis and somatic embryogenesis by culture of mature embryos. Embryogenic and nonembryogenic calli were induced from mature embryos on Murashige and Skoog (MS) medium supplemented with different concentrations of benzyl adenine (BA) and a-naphthalene acetic acid (NAA) (but not for 1.5 and 3 mg l−1 NAA). For multiplication of somatic embryoids and differentiation of shoot buds, yellow and friable embryonic calli were transferred to MS medium containing 30 g/l sucrose, 0.5 mg l−1 charcoal and 0.1 or 1 mg l−1 2,4-dichlorophenoxy acetic acid (2,4-D) or to MS medium containing 60 g l−1 sucrose, 50 mg l−1 casein hydrolysate (CH), 0.5 mg l−1 kinetin (Kin), 5 mg l−1 2,4-D and 0.5 mg l−1 charcoal. Shoot multiplication and plantlet regeneration were achieved by transferring shoot buds to MS medium supplemented with 1 mg l−1 BA or Kin.
Endopolyploidy Patterns in Organs of Trifolium Species (Fabaceae)
Authors: Kocová Valéria , Kolarcik Vladislav , Straková Nikola , Mártonfi Pavol 
Published: May 2015

Abstract
The pattern of endopolyploidy in the genus Trifolium was studied in mature organs of T. montanum and T. repens at reproductive stage, with comparative data for T. pratense, all from natural populations. Endopolyploidy in root, stem, petiole, leaf, inflorescence stalk, sepal, petal, stamen and carpel was detected by flow cytometry. 2C, 4C and 8C nuclei were found in organs of T. montanum and T. repens, and additionally 16C nuclei in organs of T. repens. The organs of T. montanum and T. repens differed in degree of endopolyploidy based on cycle values calculated from flow cytometry data; it was lowest in leaf and sepal in T. montanum and T. repens, and highest in T. montanum in petal and carpel and in T. repens in petiole and inflorescence stalk. These results are also seen in the two or more peaks of interphase nuclei in the flow cytometry histograms. There were significant correlations between the organs of T. pratense and T. repens as well as substantial differences between Trifolium species in the degree of endopolyploidy. T. pratense showed higher absolute endopolyploidy than T. montanum and T. repens. Principal component analysis showed that individuals of T. repens and T. montanum are more similar to each other than to individuals of T. pratense in degree of endopolyploidy. The observed variation between species might be explained by phylogenetic relationships and genome size differences.
Embedding in Filter-Sterilized Alginate Enhances Brassica Oleracea L. Protoplast Culture
Authors: Kiełkowska Agnieszka , Adamus Adela 
Published: May 2015

Abstract
The influence of sodium alginate sterilization on the viability and mitotic activity of embedded protoplasts was studied in protoplasts of Brassica oleracea subsp. alba and rubra isolated from hypocotyl tissue and leaves of seedlings or plants grown in vitro. Both leaf and hypocotyl-derived protoplasts were more viable and divided more frequently when embedded in filtrated alginate. Division frequency was highest in cv. Reball F1 and the mitotic activity of its protoplasts was three times higher when embedded in filtrated alginate (36.1 ± 6.8%) than when cultured in autoclaved alginate (10.9 ± 5.0%). Protoplast-derived calli colonies were transferred to solid regeneration media and plants of all tested accessions were obtained.
Morphological, Histological and Ultrastructural Changes in Fruit Epidermis of Apple Malus Domestica cv. Ligol (Rosaceae) at Fruit Set, Maturity and Storage
Authors: Konarska Agata 
Published: May 2015

Abstract
Fruit quality is closely related to the structure of the fruit peel, especially the epidermis and cuticle which form a barrier between its internal and external environments. This study used light, scanning and transmission elec-tron microscopy to examine changes in the epidermal structures of fruits of the Polish apple cultivar Malus domestica Borkh. cv. Ligol at three maturity stages. The single-layered epidermis was covered with cuticle and crystalline wax platelets. In the fruit set stage the fruit surface exhibited numerous nonglandular trichomes, stomata, microcracks and crystalline wax platelets. The surface of fruits at harvest and after 6-month controlled-atmosphere storage exhibited lenticels and horizontally or vertically oriented wax platelets. During fruit devel-opment there was an increase in epidermal cuticle thickness and a reduction in epidermal cell convexity and number of lenticels. After the storage period fruit weight declined, microcracks deepened and widened, and cuticular waxes accumulated. The cuticle was made up of two layers, lamellar and reticulate. In successive fruit development stages the width of the lamellar layer increased considerably. In the fruit set and harvest maturity stages the epidermal cells contained numerous mitochondria and plastids with starch grains. After the storage period there were fewer amyloplasts and the cell vacuoles contained flocculent residue and dark deposits.
Distribution of Arabinogalactan Proteins During Microsporogenesis in the Anther of Bellis Perennis (Asteraceae) L.
Authors: Chudzik Barbara , Szczuka Ewa , Zarzyka Barbara , Leszczuk Agata 
Published: May 2015

Abstract
Using monoclonal antibodies (mAbs) JIM13, JIM15 and MAC207, we investigated the temporal and spatial dis-tribution of some arabinogalactan protein (AGP) epitopes in cells of the Bellis perennis L. anther at different developmental stages. AGP epitopes recognized by JIM13 were detected in the protoplasts of tapetal cells, dividing microsporocytes, and microspores; AGP epitopes recognized by JIM15 were present in the cytoplasm of tapetal cells only at the stage with tetrads of microspores in the anther loculus. AGP epitopes recognized by MAC207 were present in the cells of different somatic tissues of the flower bud, but after asymmetric mitosis in the microspore they appeared abundantly in the protoplasts of immature pollen and were still present in mature pollen grains. Callose, revealed by mAb, appeared at the same stage of microsporocyte division as AGPs labelled with JIM13 and JIM15. We discuss the differences in callose and AGP localization and the possible role of the latter during anther development.