bluuebunny/crossref_metadata_2025 huggingface dataset:
Addressing the Water Issues of Tomorrow
Authors: Fedorov Andrey , Cox Angelica
Published: November 2013

The pressing water concerns of tomorrow demand that we target our time and technology in order to improve the fluid mixtures applied in fracturing operations. This challenge is intensified by the concomitant need to make use of produced water. Compelled toward this alternative as we continue to extract our remaining resources from the ground, we must account for the fact that the water we use will invariably decrease the strength of the composite fluids. Therefore, new chemicals are required to ensure stable results when testing these fluids.

Fresh Water scarcity across much of the Permian Basin is particularly critical and necessitates the pumping of produced water, thereby conserving dwindling reserves. The major problem with this approach is the need to balance the fluid recipe with chemical additives. Produced water is highly ionized and as such becomes less stable at heated temperatures, giving a smaller window to adjust chemicals for a precise formula. Hence, an innovative chemical solution is indispensable. A scale inhibitor was found to prevent scale deposition by sequestering the cationic scale-forming ions, and distorting the crystalline lattice structure. What is more, this product exhibits good thermal stability and is also very effective ion stabilizations. Accordingly the novel scale inhibitor was implemented and successfully pumped for more than 200 stages in West Texas.
Modeling Two-Phase Flowback From Multi-Fractured Horizontal Tight Gas Wells Stimulated with Nitrogen Energized Frac Fluid
Authors: Williams-Kovacs J. D. , Clarkson C. R.
Published: November 2013

In recent years it has become common practice to energize water-based fracs placed in tight gas formations with nitrogen to enhance well clean-up and maximize future reservoir performance. Despite the operational benefits, the addition of a second gas phase in the fractures complicates the quantitative analysis of flowback data.

In this work we expand on the model presented by Clarkson and Williams-Kovacs (2013) for the quantitative analysis of two-phase (water+gas) flowback data using analytical history-matching for the estimation of hydraulic fracture properties. Similar to the previous work, our interpretation is that the early flowback data corresponds to wellbore + fracture volume depletion (storage), under the assumption that fracture storage volume is much greater than wellbore storage. In cases where multi-phase matrix flow exists, this flow-regime is followed by multi-phase transient matrix linear flow. From these two flow-regimes bulk permeability (dominated by fracture permeability), effective fracture half-length and other parameters can be estimated.

To account for the addition of a nitrogen gas phase we make the assumption of perfect mixing between the hydrocarbon gas phase and nitrogen gas phase where gas composition varies as a function of time. Using this method, nitrogen mole fraction declines from an elevated value and approaches hydrocarbon gas phase nitrogen content (from standard gas analysis) once all injected nitrogen has been depleted (commonly after the flowback period). Further, all wells analyzed previously using the developed methodology have been single-phase dry shale gas wells, where we have assumed that gas is primarily sourced from the adsorbed state during flowback and fracture depletion is immediately followed by single-phase matrix linear flow. In these cases there has also been no condensate production. In the tight gas case presented in this paper, all gas is sourced from free gas and significant condensate production is seen, therefore further changing the dynamics of the problem. For the analysis, we assume that the well is being flowed above the dew point and therefore there is no free condensate flowing in the reservoir. In this example the well has also been shut-in during the flowback period to install production tubing and therefore we will examine the impact of shut-in on effective hydraulic fracture half-length. With this example we show that shutting in the well during flowback decreases the effective half-length and therefore hinders long-term production potential.
Stochastic Modeling of Multi-Phase Flowback From Multi-Fractured Horizontal Tight Oil Wells
Authors: Williams-Kovacs J. D. , Clarkson C. R
Published: November 2013

As a result of current commodity price differentials, North American resource development has shifted towards unconventional liquids-rich and light tight oil plays. Due to the low permeability of these plays, extensive hydraulic fracturing is commonly required for commercial development. Operators are seeking new methods to characterize hydraulic fractures, particularly early in the well life. One such method is to utilize regularly gathered high frequency (hourly or greater) fluid production and flowing pressures to model the flowback process. Previous studies have suggested that this data can be quantitatively analyzed to estimate hydraulic fracture half-length and other fracture properties.

Flowback of multi-fractured horizontal tight oil wells, stimulated with water-based fluids, commonly exhibit two distinct segments: a) a short period of single-phase water flow, which continues until breakthrough of formation fluids; and b) multi-phase flow (water, oil and gas) following breakthrough. The first flow regime observed in data collected at common frequencies typically consists of fracture storage/depletion of fracture fluid. This flow regime is followed by the breakthrough of hydrocarbon and formation water which results in a deviation from the depletion signature. The analysis procedure used for analyzing this data builds upon the analytical history-matching methodology presented by Clarkson and Williams-Kovacs (2013b). Consistent with the previous work we model the first segment as a single phase depletion of the fracture pore volume, from which a pre-breakthrough estimate of fracture permeability and half-length can be determined. The second segment is modelled by assuming transient linear flow of oil and formation water to the fracture, under the assumption of perfect displacement of frac water by formation fluids. From the second segment we are able to estimate long-term effective fracture permeability and half-length.

However, as pointed out by Clarkson and Williams-Kovacs (2013b) there is a large degree of uncertainty in this type of analysis as a result of the number of unknowns which are being adjusted to provide an adequate history-match. To better understand the uncertainty and the impact of each parameter, stochastic simulation will be used to provide a range of parameter values, which provide an adequate fit of the data, and to determine which parameters have the greatest impact on the match. Additional improvements over the previous work include the consideration of different fracture geometries, the use of several fracture models to estimate fracture permeability, modeling produced water salinity to track the contribution of formation water and salt dissolution and additional constraints on relative permeability curve selection. The field case presented by Clarkson and Williams-Kovacs (2013b) for a prolific light tight oil reservoir is reanalyzed, along with a second well from the same pad for proof of concept and demonstration of the developed techniques.
Microscopic Dynamics of Water and Hydrocarbon in Shale-Kerogen Pores of Potentially Mixed-Wettability
Authors: Hu Yinan , Devegowda Deepak , Striolo Alberto , Civan Faruk , Sigal Richard
Published: November 2013

Distribution of alkanes and water in organic pores of shale, referred to as kerogen, is essential information required for estimation of shale-reservoir oil- and gas-in-place, adsorption of hydrocarbon, and fate of frac-water. A practical modeling approach is presented for proper description of the kerogen pore systems with different mixed wettability, surface roughness, tortuous paths, and material disorder. Three kerogen models, namely activated kerogen, kerogen free of active sites, and grapheme-slit pore, with proper surface-oxidized functional groups and high-temperature-and-pressure maturation, are constructed by simulation. Distribution of octane and water in the organic pores of these models is predicted by molecular dynamics simulation. Comparison of results reveals the importance of accurate characterization of kerogen pore systems by particular pore morphology, surface activation, and pore size. The improved kerogen models provided here are shown to determine the placement, distribution, and trapping of frac-water in shale depending on the maturity of the kerogen within organic-rich shales.
Optimization of Cardium Fracture Design, Fracture Spacing, and Wellbore Spacing
Authors: Hards Eric , Taylor Robert , Wang Zuoyang , Fyten Glen , Storozhenko Ken
Published: November 2013

In this study of fracture design applications in the Cardium formation, a workflow designed to address the optimization of fracture size, fracture spacing, and wellbore spacing was applied to the Garrington and Pembina areas. This was performed using specific wells selected after conducting a field-wide analysis of the geological parameters relative to fracture analysis. The result was an increased understanding of how the well performance relates to locations throughout the entire reservoir rather than only a well-by-well analysis basis.

The following is an overview of the workflow used: Analysis of raw log data to calculate input data for the fracture simulator and geologic model.Importation of public domain log data from multiple wells in the study area to create a geologic model.Use of calibrated fracture simulator model to optimize fracture design based on resulting production and associated economics.Use of calculated log parameters in geological modeling software for creation of representative three-dimensional (3D) reservoir grids of reservoir pressure, relative oil permeability, porosity, and water saturation.Importation of reservoir grid properties into a fully compositional numeric reservoir simulator for optimization of fracture and wellbore spacing based on production and associated economics.
Optimization of Duvernay Fracture Design Workflow
Authors: Taylor Robert , Hards Eric , Fyten Glen , Hoch Ottmar , Storozhenko Ken , Stobo Barry , Niebergall Greg
Published: November 2013

In this study of the Kaybob area of the Duvernay formation, a process for fracture design optimization utilizing an expanded work flow was developed. Geologic maps of reservoir properties were created using specific wells selected after conducting a field-wide analysis of the geological parameters relative to fracture analysis. The result was an increased understanding of how the reservoir properties relate to various locations throughout the entire reservoir area studied rather than only a well-by-well analysis basis.

The following is an overview of the workflow used: Importation of public domain log data for multiple wells in study area.Analysis of raw log data to calculate input data for fracture simulator.Use of calculated log parameters in geological modeling software for creation of representative three-dimensional (3D) reservoir grids of reservoir pressure, relative oil permeability, porosity, and water saturation.Selection of representative wells based on accessing both typical and anomalous geological parameters as observed in the model.

In addition, a discussion is provided of the following: 5.Typical fracture design parameter ranges.6.How reservoir maps may be used to populate the grid in a fully compositional numeric reservoir simulator.7.The advantages a compositional reservoir simulator with dual permeability capability provides in characterizing production from a gas-condensate reservoir with complex fracture geometry.8.Fracturing fluid types considerations.
Viking Stimulation: Lessons Learned
Authors: Fyten Glen , Taylor Robert , Mehrabi Pejman , Hards Eric , Hoch Ottmar
Published: November 2013

In this study of the Viking formation, fracturing treatment design was optimized for the Red Water, Plato, and Dodsland areas. Fracturing treatment design for the Viking formation has evolved greatly over the last three years, with stair-step changes in production and associated economics. Some areas that lagged in production have now become the best producing Viking assets. The primary design changes that have led to these improvements in production include the following: Control of clay fines migration, given that clay content in the Viking formation can exceed 50 vol%.Control of clay swelling.Prevention of paraffin precipitation caused by injected fracturing fluids having a temperature below the cloud point of the wax in the crude.Paraffin crystal structure modification to help mitigate production issues associated with any precipitated paraffin.Use of larger proppant sizes, higher proppant concentrations, and more aggressive proppant schedules.Optimization of fracture size and spacing. Because this has been the basis of much of the success in the Viking formation in recent years, a detailed discussion follows.
Integrated Horizontal Well Placement and Hydraulic Fracture Stages Design Optimization in Unconventional Gas Reservoirs
Authors: Ma Xiaodan , Plaksina Tatyana , Gildin Eduardo
Published: November 2013

Horizontal wellbore drilling and hydraulic fracturing technologies have become standard development practices in unconventional gas reservoirs. In order to tap into the full potential of gas shale reservoirs and to produce them economically, it is essential to optimize not only the locations of hydraulic fracture (HF) stages along the given wellbore, but also the wellbore trajectory inside the reservoir. To deal with these two challenges simultaneously and in a seamless fashion, a framework of numerical optimization algorithms can be established. Application of such discrete optimization approach to the above-stated problem allows to enhance production from shale gas reservoirs and to increase the net present value (NPV) of unconventional assets.

The novel hierarchical optimization structure operates in the following way: it places a horizontal wellbore (or wellbores) on the upper level and then distributes HF stages along the fixed well trajectory (or trajectories) on the lower level. Both levels of the framework use gradient-based stochastic strategy, namely, the simultaneous perturbation stochastic approximation (SPSA). Application of this optimization technique permits to depart from the common practice of distributing HF stages evenly. We demonstrate utility of this idea with highly heterogeneous geologic systems that require HF spacing with non-even intensity. To assess efficiency of our approach, we compare the results obtained from SPSA optimization with those from Covariance Matrix Adaptation Evolution Strategy (CMA-ES) that is a stochastic, derivative-free numerical method. The developed framework is tested on stimulation data from synthetic models. Our findings show that the systematic approach to optimization of horizontal wellbore and HF stages placement can improve the NPV of unconventional projects.
Relations between Shear and Compressional Wave Velocities of Geological Formations in Alberta, Canada Based on a Log-Derived Database
Authors: Soltanzadeh Hamidreza
Published: November 2013

For decades, the Alberta Basin has been the subject of several underground operations for mining and conventional and unconventional petroleum production. In addition, it is a potential locus for new underground operations such as geothermal energy production, storage of compressed air, and CO2 storage. Considering the importance of this region, a database of rock properties based on the existing wireline logs in more than 2200 wells in Alberta was developed by the author. This database includes rock properties such as porosity, density, shear and compressional wave velocities and dynamic elastic parameters for the formations intersected by these wells, along with the statistical analyses of these data to evaluate the reliability of the measurements. In this paper, it is shown that the data presented in this database might be utilized to study potential meaningful relationships between shear and compressional wave velocities for different geological formations in Alberta. These relationships can be extremely valuable because shear sonic logs are usually scarce compared to compressional sonic logs. Developing such correlations is common in the field of geophysics and they are widely used to estimate shear wave velocities from measured values of compressional wave velocities for various seismic interpretation applications and geomechanical characterization. Studies presented in this paper show that, for a notable number of geological formations in the Alberta Basin, strong linear correlations exist between shear and compressional wave velocities. As one of the major targets for conventional and unconventional oil recovery, the Viking Formation in Alberta was selected to demonstrate the capabilities of the developed database.
Decline Curve Analysis for Unconventional Reservoir Systems — Variable Pressure Drop Case
Authors: Ilk D. , Blasingame T. A.
Published: November 2013

The premise of this work is the development and application of a new methodology to forecast production data in unconventional reservoirs where variable rate and pressure drop data are typically observed throughout production. Decline curve analysis techniques for the estimation of ultimate recovery (EUR) require the constant bottomhole pressure condition during the producing life of the well — whereas it is not regular practice to maintain a constant bottomhole pressure profile throughout production in unconventional reservoirs. Therefore, the applicability of the time-rate decline relations is questionable, and methods to remove pressure variations from rate response are needed for generating future production forecasts.

From a conceptual view point, we propose the utilization of the convolution/superposition theory along with the recently developed "empirical" time-rate equations, which are normalized by pressure drop data. In order to avoid non-uniqueness, a workflow is used where model parameters for the "normalized" decline curve equations are identified using diagnostic "qDb" plots. Normalized decline curve equations are then convolved with the pressure drop data to achieve a history match and to forecast production.

We provide demonstrative application of this technique using an example from an high pressure high temperature shale gas reservoir. For varying bottomhole pressure cases, we show that our proposed techniques effectively remove pressure variations from the rate history. We present the differences in computed EUR values using decline curve analysis with and without corrections for varying pressures. In addition, forecasts are generated using supplementary plots such as pressure drop normalized rate versus cumulative production.
Well Flow Dynamic Modelling – the Tool to Optimize Well Operations
Authors: Konstantin Petrukhin
Published: November 2013

Over the last years there is a great progress in the dynamic simulation approach to wellbore processes modeling. First of all, it is explained by the reason that classic modeling method (nodal analysis) is unable to take into account every wellbore transient processes completely. The processes, in their turn, constitute an integral part of the well performance during the start-ups – shutdowns, changes of well operation mode.

The main objective of this study is to develop qualitative and quantitative understanding of well transient processes and opportunity to optimize the well operation as well. This problem is important today because there is no reliable instrument enabling to estimate and optimize well operation under the transient processes.
Roles of Biology, Chemistry, and Physics in Soil Macroaggregate Formation and Stabilization
Authors: Nichols Kristine A. , Halvorson Jonathan J.
Published: November 2013

Many soil functions depend on the distribution of macro- (≥ 0.25 mm) and micro- (< 0.25 mm) aggregates and
open space between aggregates (i.e. soil structure). Despite the importance of macroaggregates in soil, little is understood
about how they form and become stable. We hypothesize that biological activities, chemical reactions, and physical forces
which help to form macroaggregates differ from those involved in stabilization. Formation is a binding process where aggregate
components are brought spatially closer together, ‘bagged’ or enmeshed by roots and fungal hyphae and ‘glued’
by labile SOM. Stabilization involves bonding processes between organic matter, clay minerals, cations, or plant or microbial
biomolecules which increase internal cohesiveness. By separating aggregate formation from stabilization, the biological,
chemical, and physical processes involved in maintaining long-term soil quality through stabilized soil structure
will be more easily identified.
The Calculation Model of Initiation Pressure During Hydraulic Fracturing Process of Perforated Coal Seams
Authors: Yuwei Li , Chi Ai
Published: November 2013

There are lots of cleats, fractures and many other structure weak planes in coal seams, which make the bullet
holes and cleats intersecting. During the hydraulic fracturing process in coal seams, fractures will initiate at coal rock
body of borehole wall, and cleats or fractures are different from conventional reservoirs. Thus a new model for initiation
pressure calculation during coal seams fracturing should be established. Based on the rock mechanics and elasticity
mechanics, and also on network distribution characteristics of coal seam cleats and the space position relationships
between the intersected bullet holes and cleats, stress distribution around the bullet holes and at the cleats wall were
deducted. The model was established in tensile failure condition. The calculated initiation fracture pressure of Well HX-3
was 10.71MPa. The pressure obtained from bottom hole pressure gauge was 11.24MPa. The relative error was 4.72%.
The model could be applied for initiation pressure calculation during hydraulic fracturing process in coal seams. The
fractures would initiate at the cleats during fracturing.
Clinical and histopathological characteristics in patients with postmenopausal bleeding
Authors: Mandic Aljosa , Gutic Bojana , Kapicl-Ivkovic Tatjana , Segedi-Mladenovic Ljiljana , Mocko-Kacanski Mihaela
Published: November 2013

Background: Incidence of endometrial carcinoma in Vojvodina is 15-20/100 000.
In 75% cases, endometrial carcinoma is diagnosed in postmenopausal period. In
90 % of patients, the first clinical sign is postmenopausal bleeding. The aim
of the study was to investigate clinical and histopathological
characteristics in patients with postmenopausal bleeding. Methods: The study
included 122 patients with postmenopausal bleeding. All of these patients
underwent gynecological examination and vaginal ultrasound. We obtained
materials for histopathological analysis by fractionate explorative
curettage. Once we had definitive histopathological findings, we divided
patients in two groups A (endometrial carcinoma) and B (benign changes).
Results: We confirmed significant statistical differences between examined
group A and B, including age (64.49 compared with 58.81 years),
postmenopausal period (13.67 instead 9.11 years), and length of uterine
corpus (6.41 instead 5.25 cm). Conclusion: Elderly women with longer
postmenopausal interval and postmenopausal bleeding had increased risk for
endometrial carcinoma. Measurement of endometrial thickness by transvaginal
ultrasound appeared to be insufficient parameter for differentiating the
benign from the malignant changes of endometrium. Patients with endometrial
carcinoma had significantly longer corpus of uterus comparing to patients
with benign changes. Body mass index was not found to be significant risk
factor in development of endometrial carcinoma in the examined groups.
Obesity was diagnosed in both groups, suggesting that increased body mass
index is a risk factor for development of pathological changes in
endometrium, which could lead to postmenopausal bleeding.
The use of vegetative compatibility tests for identification of biodiversity of phytopathogenic fungi
Authors: Krnjaja Vesna , Levic Jelena , Stankovic Slavica , Vasic Tanja
Published: November 2013

Visual assessment of phenotypes, performed when two strains of one fungal
species are cultivated in a mixed culture on specific media, is known as
vegetative or heterokaryotic compatibility or incompatibility test, which
enables identification of fungal clones and their classification based on
phylogenetic groups. Hyphae of strains that have identical alleles at all vic
loci can anastomose into a form of a visible heterokaryon. Strains that
divide compatible loci and can anastomose each other belong to a
subpopulation termed the vegetative compatibility group (VCG), which is
genetically distinguishable from other VCGs. Each VCG is specific regarding
its host plant or related host groups and can, but does not have to be
virulent on other hosts. Vegetative compatibility can be established in
different ways, but complementary auxotrophic strains or strains formed by
spontaneous mutation during nutrition, capable of forming a prototrophic
heterokaryon are predominantly used. The nit mutants are considered excellent
genetic markers for determination of vegetative compatibility and grouping of
strains or clones of one fungus into the same or different VCGs. The ability
only to determine whether strains are the same or not, but not the degree of
their relatedness using VCG, is a limiting factor in analyses that could be
performed. VCGs are the most efficient when they are employed to detect the
presence of a specific strain in a population. This paper provides an
overview of the importance of the phenomenon of vegetative compatibility.
Vegetative compatibility is one of the most important genetic traits in
ascomycetes by which one subpopulation can be identified as a distinct
genetic group. Furthermore, the procedures for isolation, identification and
determination of nit mutant phenotypes, and for identification of
complementary strains and VCGs are described in detail.
Impact of Trichoderma spp. on soybean seed germination and potential antagonistic effect on Sclerotinia sclerotiorum
Authors: Tancic Sonja , Skrobonja Jelica , Lalosevic Mirjana , Jevtic Radivoje , Vidic Milos
Published: November 2013

Trichoderma species have been registered as species with important plant
growth promoting potential and antagonistic effect against various
phytopathogens. Trichoderma isolates originating from different soil types
from the Vojvodina region (Serbia) were screened using dual culture test for
their antagonistic effect against the pathogen Sclerotinia sclerotiorum. All
tested isolates had high radial growth inhibition (RGI) factors of the
pathogen and high colonization percentage. Growth promoting activity of
Trichoderma isolates on soybean seeds was tested under glasshouse conditions.
Soybean seeds were coated with suspensions of different Trichoderma isolates
and seed germination percentage, root and shoot length were measured.
According to data analysed in Statistica 10, using Duncan?s test, there were
no significant effects on shoot length among the tested isolates, compared to
the control. The four tested Trichoderma isolates showed significant positive
effects on germination, root length and vigour index, while two isolates
exhibited no significant effect on any of the measured parameters.
The effects of Kingbo biopesticide on Tetranychus urticae Koch female adults
Authors: Medjo Irena , Marcic Dejan
Published: November 2013

Toxic and sublethal effects of the biopesticide Kingbo (oxymatrine 0.2% +
psoralen 0.4%) on female adults of two-spotted spider mite (Tetranychus
urticae Koch) were investigated in two laboratory bioassays. The assays were
set up in four replicates on bean leaf discs (30 mm in diameter) placed on
moistened cotton wads in Petri dishes. Preovipositional females were then
released on them and treated directly with the biopesticide at a
concentration series using a Potter device (2 ml liquid, 100 kPa air
pressure, 2.7 ? 0.2 mg/cm2 aqueous deposit). Each replicate included 4-7
Petri dishes containing a total of 20-35 females. In the first assay, females
were exposed to continuous acaricidal activity on treated discs over a period
of 96 h; in the second assay, they were exposed for 24 h and then transferred
to untreated discs and kept there for the next 72 h. Kingbo toxicity to
females, expressed as LC50, was significantly higher in the first bioassay
(14.83 ?l/l) than in the second one (26.39 ?l/l). Total gross fecundity of
females in the first assay was reduced by 37-95% and net fecundity by 48-97%,
depending on concentration; in the second assay, the respective fecundity
reductions were 15-87% and 23-91%. We found that a 24 h exposure to the
biopesticide Kingbo was sufficient for sustaining significant toxic and
sublethal effects. Further research should provide additional data on the
recovery potential of T. urticae populations.
A bioassay technique to study clomazone residues in sandy loam soil
Authors: Gajic-Umiljendic Jelena , Radivojevic Ljiljana , Djordjevic Tijana , Jovanovic-Radovanov Katarina , Santric Ljiljana , Djurovic-Pejcev Rada , Elezovic Ibrahim
Published: November 2013

A bioassay test was conducted to evaluate the sensitivity of maize, sunflower
and barley to clomazone residues in sandy loam soil. Clomazone was applied at
different rates from 0.12 to 12 mg a.i./kg of soil. The parameters measured
14 days after treatment were: shoot height, fresh and dry weight, and content
of pigments (carotenoids, chlorophyll a and chlorophyll b). The results
showed that the lowest clomazone concentration caused a significant reduction
in all measured parameters for barley and sunflower shoots. Fresh weight of
maize shoots was not sensitive to clomazone residual activity in soil while
the other parameters were highly inhibited. Nomenclature: clomazone
(2-(2-chlorbenzyl)-4,4-dimethyl-1,2-oxazolidin-3-one), maize (Zea mays L.),
sunflower (Helianthus annuus L.), barley (Hordeum vulgare L.).
Display probability of symbol errors for MQAM on Rician fading channel based on MGF method
Authors: Jovanovic Predrag , Mitic Dragan , Lebl Aleksandar , Rajkovic Radoslav
Published: November 2013

In this paper, we present a method to calculate the probability of error per
symbol (Symbol Error Probability, SEP) of M-ary Quadrature Amplitude
Modulation (MQAM) over a slow, flat, identically independently distributed
Rician fading channels. Since the fading is one of the major constraints in
wireless communications, then diversity modulation technique is used for the
efficient transfer of message signals. Exact analysis of error probability
per symbol for MQAM, transmitted over Rician fading channels, is performed by
N branches of diversity reception using maximum ratio of signal-to-noise
power (maximal-ratio-combining, MRC), where the information in the channel on
the receiver side is known. The performances of MQAM over Rician fading
channels are here also analyzed. Approximate formula is used to represent SEP
for MQAM transmitted over Gaussian channels. Boundary condition for the
approximation is M?4 and 0?SNR?30 dB.
Narrative Disclosure and Earnings Performance: Evidence from R&D Disclosures
Authors: Merkley Kenneth J.
Published: November 2013

This paper examines how earnings performance relates to firms' narrative R&D disclosure decisions. The unique nature of R&D investments and financial statements' limited ability to communicate the value of such investments highlight the role of narrative disclosure as a supplement to the financial statements. I predict and find that current earnings performance (adjusted for R&D expense) is negatively related to the quantity of narrative R&D disclosure. Conducting a content analysis of the detail, tone, and readability of narrative R&D disclosures, I find that managers adjust R&D disclosures based on earnings performance to provide relevant information rather than to obfuscate performance. Finally, I provide evidence that market participants find narrative R&D disclosure informative because it significantly affects sell-side analyst behavior, disclosure information content, and information asymmetry.

Data Availability: Data are available from sources identified in the text.
Effect of Double-layer Application on Dentin Bond Durability of One-step Self-etch Adhesives
Authors: Taschner M , Kümmerling M , Lohbauer U , Breschi L , Petschelt A , Frankenberger R
Published: November 2013

Purpose

The aim of this in vitro study was 1) to analyze the influence of a double-layer application technique of four one-step self-etch adhesive systems on dentin and 2) to determine its effect on the stability of the adhesive interfaces stored under different conditions.

Materials and Methods

Four different one-step self-etch adhesives were selected for the study (iBondSE, Clearfil S3 Bond, XenoV+, and Scotchbond Universal). Adhesives were applied according to manufacturers' instructions or with a double-layer application technique (without light curing of the first layer). After bonding, resin-dentin specimens were sectioned for microtensile bond strength testing in accordance with the nontrimming technique and divided into 3 subgroups of storage: a) 24 hours (immediate bond strength, T0), b) six months (T6) in artificial saliva at 37°C, or c) five hours in 10 % NaOCl at room temperature. After storage, specimens were stressed to failure. Fracture mode was assessed under a light microscope.

Results

At T0, iBond SE showed a significant increase in microtensile bond strength when the double-application technique was applied. All adhesive systems showed reduced bond strengths after six months of storage in artificial saliva and after storage in 10% NaOCl for five hours; however at T6, iBond SE, Clearfil S3 Bond, and XenoV+ showed significantly higher microtensile bond strength results for the double-application technique compared with the single-application technique. Scotchbond Universal showed no difference between single- or double-application, irrespective of the storage conditions.

Conclusion

The results of this study show that improvements in bond strength of one-step self-etch adhesives by using the double-application technique are adhesive dependent.
Stable cohomology of alternating groups
Authors: Bogomolov Fedor , Böhning Christian
Published: November 2013

We determine the stable cohomology groups ($$H_S^i \left( {{{\mathfrak{A}_n ,\mathbb{Z}} \mathord{\left/
{\vphantom {{\mathfrak{A}_n ,\mathbb{Z}} {p\mathbb{Z}}}} \right.
\kern-\nulldelimiterspace} {p\mathbb{Z}}}} \right)$$ of the alternating groups $$\mathfrak{A}_n$$ for all integers n and i, and all odd primes p.
Method to obtain carbon nano-onions by pyrolisys of propane
Authors: Garcia-Martin Tomas , Rincon-Arevalo Pedro , Campos-Martin Gemma
Published: November 2013

We present a new and simple method for carbon nano-onions (CNOs) production which is based on the pyrolysis of Propane. CNOs are originated in a laminar premixed Propane/Oxygen flame of approximately 1.8 of stoichiometric coefficient. The stream of gasses resulting from the combustion drives the carbon particles towards the aluminium surface on which nano-onions are deposited and collected. The structure and size of the deposited carbon onion on the metal wall are characterized by High Resolution Transmission Electron Microscopy technique (HRTEM). The experimental images show the presence of two different types of CNOs. The first particles have diameters in the range of 18-25 nm and the second ones around 10 nm.
Collision of water wave solitons
Authors: Fenyvesi Nora , Bene Gyula
Published: November 2013

A classification of the time evolution of the two-soliton solutions of the Boussinesq equation is given, based on the number of extrema of the wave. For solitons moving in the same directions, three different scenarios are found, while it is shown that only one of these scenarios exists in case of oppositely moving solitons.
Semi-Huber quadratic function and comparative study of some MRFs for Bayesian image restoration
Authors: de la Rosa J. I. , Villa-Hernández J. , González-Ramírez E. , de la Rosa M. E. , Gutiérrez O. , Olvera-Olvera C. , Castañeda-Miranda R. , Fleury G.
Published: November 2013

The present work introduces an alternative method to deal with digital image restoration into a Bayesian framework, particularly, the use of a new half-quadratic function is proposed which performance is satisfactory compared with respect to some other functions in existing literature. The bayesian methodology is based on the prior knowledge of some information that allows an efficient modelling of the image acquisition process. The edge preservation of objects into the image while smoothing noise is necessary in an adequate model. Thus, we use a convexity criteria given by a semi-Huber function to obtain adequate weighting of the cost functions (half-quadratic) to be minimized. The principal objective when using Bayesian methods based on the Markov Random Fields (MRF) in the context of image processing is to eliminate those effects caused by the excessive smoothness on the reconstruction process of image which are rich in contours or edges. A comparison between the new introduced scheme and other three existing schemes, for the cases of noise filtering and image deblurring, is presented. This collection of implemented methods is inspired of course on the use of MRFs such as the semi-Huber, the generalized Gaussian, the Welch, and Tukey potential functions with granularity control. The obtained results showed a satisfactory performance and the effectiveness of the proposed estimator with respect to other three estimators.
A direct comparison between a MEMS deformable mirror and a liquid crystal spatial light modulator in signal-based wavefront sensing
Authors: Jewel A. R. , Akondi V. , Vohnsen B.
Published: November 2013

Aberrations degrade the performance of optical systems in terms of resolution and signal-to-noise ratio. This work explores the feasibility of a signal-based wavefront sensor, which employs a search algorithm to estimate Zernike coefficients of given aberrations. The search algorithm was supported by Gaussian interpolation. The performance of two different reflective wavefront correctors, a deformable mirror and a spatial light modulator in signal-based wavefront sensing, was compared under identical conditions. The aberrations were introduced by using another identical high resolution reflecting spatial light modulator. The performance was quantified using the Strehl ratio, which was estimated from simultaneously acquired Hartmann-Shack measurements of Zernike coefficients. We find that the spatial light modulator can be a good alternative to the deformable mirror in terms of dynamic range and sensitivity, when speed is not a limiting factor. Distinct advantages of the spatial light modulator are high number of pixels and a larger active area.
Bioavailability of Plant-Derived Antioxidants
Authors: Abourashed Ehab
Published: November 2013

Natural products with antioxidant properties have been extensively utilized in the pharmaceutical and food industry and have also been very popular as health-promoting herbal products. This review provides a summary of the literature published around the first decade of the 21st century regarding the oral bioavailability of carotenoids, polyphenols and sulfur compounds as the three major classes of plant-derived antioxidants. The reviewed original research includes more than 40 compounds belonging to the above mentioned classes of natural antioxidants. In addition, related reviews published during the same period have been cited. A brief introduction to general bioavailability-related definitions, procedures and considerations is also included.
Shear-Jamming in Two-Dimensional Granular Materials with Power-Law Grain-Size Distribution
Authors: Herman Agnieszka
Published: November 2013

Although substantial progress has been made in recent years in research onsheared granular matter, relatively few studies concentrate on the behavior of materials withvery strong polydispersity. In this paper, shear deformation of a two-dimensional granularmaterial composed of frictional disk-shaped grains with power-law size distribution isanalyzed numerically with a finite-difference model. The analysis of the results concentrateson those aspects of the behavior of the modeled system that are related to its polydispersity. Itis demonstrated that many important global material properties are dependent on the behaviorof the largest grains from the tail of the size distribution. In particular, they are responsiblefor global correlation of velocity anomalies emerging at the jamming transition. They alsobuild a skeleton of the global contact and force networks in shear-jammed systems, leadingto the very open, “sparse” structure of those networks, consisting of only ~ 35% of all grains.The details of the model are formulated so that it represents fragmented sea ice moving ona two-dimensional sea surface; however, the results are relevant for other types of stronglypolydisperse granular materials, as well.
The Genetics of Diabetic Nephropathy
Authors: Brennan Eoin , McEvoy Caitríona , Sadlier Denise , Godson Catherine , Martin Finian
Published: November 2013

Up to 40% of patients with type 1 and type 2 diabetes will develop diabetic nephropathy (DN), resulting in chronic kidney disease and potential organ failure. There is evidence for a heritable genetic susceptibility to DN, but despite intensive research efforts the causative genes remain elusive. Recently, genome-wide association studies have discovered several novel genetic variants associated with DN. The identification of such variants may potentially allow for early identification of at risk patients. Here we review the current understanding of the key molecular mechanisms and genetic architecture of DN, and discuss the merits of employing an integrative approach to incorporate datasets from multiple sources (genetics, transcriptomics, epigenetic, proteomic) in order to fully elucidate the genetic elements contributing to this serious complication of diabetes.
Pd0-Catalyzed Methyl Transfer on Nucleosides and Oligonucleotides, Envisaged as a PET Tracer
Authors: James Damien , Escudier Jean-Marc , Szlosek-Pinaud Magali , Fouquet Eric
Published: November 2013

The methyl transfer reaction from activated monomethyltin, via a modified Stille coupling reaction, was studied under “ligandless” conditions on fully deprotected 5'-modified nucleosides and one dinucleotide. The reaction was optimized to proceed in a few minutes and quantitative yield, even under dilute conditions, thus affording a rapid and efficient new method for oligonucleotide labelling with carbon-11.
Deep Oxidative Desulfurization of Dibenzothiophene in Simulated Oil and Real Diesel Using Heteropolyanion-Substituted Hydrotalcite-Like Compounds as Catalysts
Authors: Yu Fengli , Wang Rui
Published: November 2013

Three heteropolyanion substituted hydrotalcite-like compounds (HPA-HTLcs) including Mg9Al3(OH)24[PW12O40](MgAl-PW12), Mg9Al3(OH)24[PMo12O40] (MgAl-PMo12) and Mg12Al4(OH)32[SiW12O40] (MgAl-SiW12), were synthesized, characterized and used as catalysts for the oxidative desulfurization of simulated oil (dibenzothiophene, DBT, in n-octane). MgAl-PMo12 was identified as an effective catalyst for the oxidative removal of DBT under very mild conditions of atmospheric pressure and 60 °C in a biphasic system using hydrogen peroxide as oxidant and acetonitrile as extractant. The conversion of DBT was nearly 100%. As a result, because of the influence of the electron density and the space steric hindrance, the oxidation reactivity of the different sulfur compounds in simulated oil followed the order DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT) > thiophene (TH). When the reaction is finished, the catalysts can be recovered from the acetonitrile phase by filtration. The recovered MgAl-PMo12 retains nearly the same catalytic activity as the fresh material. Moreover, MgAl-PMo12 was found to exhibit an ideal catalytic activity in the oxidative desulfurization of real diesel resulting in a total remaining sulfur content of 9.12 ppm(w).
Finger-Vein Verification Based on Multi-Features Fusion
Authors: Qin Huafeng , Qin Lan , Xue Lian , He Xiping , Yu Chengbo , Liang Xinyuan
Published: November 2013

This paper presents a new scheme to improve the performance of finger-vein identification systems. Firstly, a vein pattern extraction method to extract the finger-vein shape and orientation features is proposed. Secondly, to accommodate the potential local and global variations at the same time, a region-based matching scheme is investigated by employing the Scale Invariant Feature Transform (SIFT) matching method. Finally, the finger-vein shape, orientation and SIFT features are combined to further enhance the performance. The experimental results on databases of 426 and 170 fingers demonstrate the consistent superiority of the proposed approach.
Immunoassays and Biosensors for the Detection of Cyanobacterial Toxins in Water
Authors: Weller Michael
Published: November 2013

Algal blooms are a frequent phenomenon in nearly all kinds of fresh water. Global warming and eutrophication by waste water, air pollution and fertilizers seem to lead to an increased frequency of occurrence. Many cyanobacteria produce hazardous and quite persistent toxins, which can contaminate the respective water bodies. This may limit the use of the raw water for many purposes. The purification of the contaminated water might be quite costly, which makes a continuous and large scale treatment economically unfeasible in many cases. Due to the obvious risks of algal toxins, an online or mobile detection method would be highly desirable. Several biosensor systems have been presented in the literature for this purpose. In this review, their mode of operation, performance and general suitability for the intended purpose will be described and critically discussed. Finally, an outlook on current developments and future prospects will be given.
The French Participation in the Korean War and the Establishment of a “Path of Memory” in South Korea
Authors: Quisefit Laurent
Published: November 2013

The contribution to the Korean War of medium powers or declining great powers like France has been scarcely investigated in-depth despite France’s marked contribution to the conflict, both diplomatically and militarily. Though its contribution modest by way of the number of troops sent to Korea and discreet on the diplomatic field, the French part in the war was significant, because it demonstrated the solidarity of the Allied powers united in the newly-established NATO. Moreover, the French battalions sent to Korea fought with gallantry and gained many medals, including silver stars. From the beginning of the 2000s, this overlooked history began to be noticed with the building of a “Path of the Living Memory of the French Contribution to the Korean War”. It was intended to inform visitors about a part of history, to transmit memory, and to strengthen friendship between France and Korea.