bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineered LCM Design Yields Novel Activating Material for Potential Application in Severe Lost Circulation Scenarios
Authors: Savari Sharath , Kumar Arunesh , Whitfill Donald L. , Miller Matthew , Murphy Robert J. , Jamison Dale E. 
Published: April 2013

Abstract
Particulate lost circulation materials (LCM) that work for severe-to-total losses are difficult, if not impossible, to find. Solutions that are effective for lower loss rates do not perform well at higher loss rates. Many LCM formulations have been used to treat severe losses, but their design and use has been more trial and error based mostly upon successful case histories. This paper describes the development of a combination of materials that is used in conjunction with other Engineered, Composite Solutions (ECS) to further enhance their performance.
A novel combination of swelling materials, retarder, and fibers with a large aspect ratio is proposed as an activator that can be deployed with ECS typically available on the rig. The activator was designed and tested under conditions that qualitatively resemble severe lost circulation scenarios (large fractures). A shale swell meter was modified to qualitatively compare the swelling behaviour of different materials under different temperatures and retarder concentrations. A polyacrylamide-based swelling material was found to be sensitive to both temperature and retarder concentration. A newly sourced, potentially reservoir-friendly swelling material was found to be sensitive to temperature only. The activator-ECS combinations were tested for plugging capability with Permeability Plugging Apparatus (PPA) test equipment using different size tapered slots. Data from these modified PPA tests were used to determine the best combination of activator and ECS for plugging a particular-sized fracture simulated by the tapered slot.
Field applications of systems that led to this proposed approach are discussed along with laboratory data comparing the swelling behaviour of different materials as related to mixing and pumping times.
Characterizing Coal Bed Methane Using Pressure Buildup and Falloff Data Acquired with Wireline Formation Testers: Case Studies
Authors: Harfoushian Jack , Osman Magdy Samir , Zerba Cesar 
Published: April 2013

Abstract
Over the past few years there has been a surge of interest in coal bed methane (CBM) resources in many parts of the world. Also known as coal seam gas (CSG), CBM has become an important source of energy because of increasing global demand for cleaner fuels. CBM is distinct from conventional hydrocarbon reservoirs as methane is stored within coals by adsorption. With matrix porosity generally lower than 4%, cleats and fractures are the main conduits for production from coals. Given differences in structure compared to conventional reservoirs, drilling into coal seams requires the use of minimum overbalance and nondamaging fluids. In addition, evaluation of CBM reservoirs has many technical challenges. One of the main challenges is to ascertain coal cleat behavior and estimate permeability and ultimately productivity of a target zone. Traditionally this has been done by production or injection tests using conventional testing techniques. In Australia, a wireline-deployed straddle packer configuration was used to address this challenge, with demonstrated benefits for determining permeability and productivity.
Unlike traditional methods of conducting a closed chamber test across a large interval, this methodology uses a straddle packer with a downhole pump in a toolstring deployed on wireline. The packer spacing can be adjusted prior to deployment to suit the expected height of the coal bed to be tested. The tool is capable of both injection into and production from a coal bed interval with a much smaller storage volume compared to conventional test strings. Pressure is continuously monitored in real time ensuring that acceptable limits are not exceeded during either the injection or drawdown phases, to avoid excessive force on a coal seam while maintaining single-phase flow. The analysis of both drawdown-buildup and injection-falloff results reveals the strengths and limitations of the two techniques.
New Analytical Equations of Recovery Factor for Radial Flow Systems
Authors: Zhang He , Ling Kegang , Acura Herman 
Published: April 2013

Abstract
This paper presents analytical algorithms to calculate ultimate recovery factors for radial flow systems. The approaching method is similar to the well-recognized Buckley-Leverett equations, but it's accurate for matured fields, especially peripheral water-flooding reservoirs.
Buckley-Leverett displacement equations have been derived strictly from linear flow systems, and have been verified by linear flow experiments only. However, nowadays, it's very common to observe multiple water injectors drilled around producers to enhance the recovery factor in mature fields. New analytical equations that consider non-linear flow patterns are more appropriate for these types of operations.
The new equations proposed in this paper have been verified with real field data. The original Buckley-Leverett equation generally results in much lower recovery factors that barely match the cumulative production. Consequently, the estimated ultimate recovery (EUR) by volumetric methods tends to be too low. As a result, the production projections according to match this EUR are not reasonable when compared to the historical performance of the wells and Decline Curve Analysis (DCA). The proposed analytical model improves the prediction of reservoir performance. It works as an important supplement to the Buckley-Leverett method for oil fields worldwide.
Hydraulic Pumping Units Proving Very Successful in Deliquifying Gas Wells in East Texas
Authors: Beard David 
Published: April 2013

AbstractIntensified US exploration and production activity in the liquids-rich shale plays has tended to overshadow issues with base gas production, particularly the continuing struggle to remediate liquid loading and return pressure-depleted wells to production. In recent years, Devon Energy has intensified efforts to maximize base gas production through deliquification of its mature East Texas wells. Accordingly, the operator has realized tremendous success with artificial lift, which is generating an average 50% rate of return and effectively breathing new life into many of its old and struggling wellbores. More recently, Devon has focused its efforts on the use of Hydraulic Pumping Units (HPU), which have recorded an amazing track record in deliquifying and returning to production low-rate gas wells that no longer respond to plungers, soap or velocity strings.This paper examines Devon's experience using HPU to deliquify East Texas wells in reservoirs that vary from very low bottomhole pressure with high permeability to higher pressure with very low permeability and everything in between. The targeted wells range in depth from 5,000 ft to 10,000 ft with wellbores between 2 7/8 to 7 in. diameters. All of these well types have been put on pump and responded very favorably.The authors will review case histories from several divergent East Texas well types to illustrate the efficiency of pumping units in restoring production to these lower fluid rate wells. The discussion will focus on a newly engineered HPU, which comprises a vertical hydraulic cylinder on the wellhead to reciprocate the rods and pump and offers a number of HSE, operational and economic advantages over conventional pumping units. The specific features that make the HPU a very viable and often preferred alternative to conventional pumping units will be detailed, as will the growing pains and subsequent lessons learned in the East Texas deliquification campaign. Owing largely to the impressive results in the East Texas production-restoration program, HPU technology has since expanded throughout other US gas basins where liquid loading has become a predominate issue.
In Vivo Assessment of Pulmonary Arterial Wall Fibrosis by
Intravascular Optical Coherence Tomography in
Pulmonary Arterial Hypertension:
A New Prognostic Marker of Adverse Clinical Follow-Up§
Authors: Domingo Enric , Grignola Juan C , Aguilar Rio , Montero María Angeles , Arredondo Christian , Vázquez Manuel , López-Messeguer Manuel , Bravo Carlos , Bouteldja Nadia , Hidalgo Cristina , Roman Antonio 
Published: April 2013

Background:
The aim is to correlate pulmonary arterial (PA) remodeling estimated by PA fibrosis in PA hypertension (PAH) with clinical follow-up. Histology of PA specimens is also performed.

Methods:
19 patients, aged 54±16 (4 men), functional class II-III were studied with right heart catheterization, PA Intravascular Ultrasound and optical coherence tomography (OCT) in inferior lobe segment. PA wall fibrosis was obtained by OCT ( area of fibrosis/PA cross sectional area × 100). Patients follow-up was blind to OCT. Events were defined as mortality, lung transplantation, need of intravenous prostaglandins or onset of right ventricular failure.

Results:
OCT measurements showed high intra- and interobserver agreement. There was a good correlation between OCT and histology in PA fibrosis from explanted lungs. Area of fibrosis was 1.4±0.8 mm2, % fibrosis was 22.3±8. Follow-up was 3.5 years (2.5-4.5). OCT %Fib was significantly correlated with PA capacitance (r=-0.536) and with pulmonary vascular rsistance (r=0.55). Patients were divided according to the median value of PA fibrosis. There were 10 patients with a high (≥ 22%) and 9 with a low fibrosis (<22%). Events occurred in 6 (1 death, 1 lung transplantation, 2 intravenous prostaglandins, 2 right heart failure) out of 10 patients with high and in 0 out of 9 patients with low fibrosis (p<0.01).

Conclusions:
In PAH, the severity of PA remodeling assessed by OCT wall fibrosis was significantly predictive of severely unfavorable clinical outcome. In vivo assessment of pulmonary arterial wall fibrosis by intravascular OCT in PAH is a promising new prognostic marker of adverse clinical outcome.
Thin Wall Ductile Iron Castings: Technological Aspects
Authors: Fraś E. , Górny M. , Kapturkiewicz W. 
Published: April 2013

Abstract
The paper discusses the reasons for the current trend of substituting ductile iron castings by aluminum alloys castings. However, it has been shown that ductile iron is superior to aluminum alloys in many applications. In particular it has been demonstrated that is possible to produce thin wall wheel rim made of ductile iron without the development of chills, cold laps or misruns. In addition it has been shown that thin wall wheel rim made of ductile iron can have the same weight, and better mechanical properties, than their substitutes made of aluminum alloys.
Application of Averaged Voronoi Polyhedron in the Modelling of Crystallisation of Eutectic Nodular Graphite Cast Iron
Authors: Burbelko A.A. , Początek J. , Królikowski M. 
Published: April 2013

Abstract
The study presents a mathematical model of the crystallisation of nodular graphite cast iron. The proposed model is based on micro- and macromodels, in which heat flow is analysed at the macro level, while micro level is used for modelling of the diffusion of elements. The use of elementary diffusion field in the shape of an averaged Voronoi polyhedron [AVP] was proposed. To determine the geometry of the averaged Voronoi polyhedron, Kolmogorov statistical theory of crystallisation was applied. The principles of a differential mathematical formulation of this problem were discussed. Application of AVP geometry allows taking into account the reduced volume fraction of the peripheral areas of equiaxial grains by random contacts between adjacent grains. As a result of the simulation, the cooling curves were plotted, and the movement of "graphite-austenite" and "austenite-liquid” phase boundaries was examined. Data on the microsegregation of carbon in the cross-section of an austenite layer in eutectic grains were obtained. Calculations were performed for different particle densities and different wall thicknesses. The calculation results were compared with experimental data.
The oldest Cambrian trilobites from the Holy Cross Mountains, Poland: taxonomic, stratigraphic and biogeographic reappraisal
Authors: Żylińska Anna 
Published: April 2013

Abstract
Żylińska, A. 2013. The oldest Cambrian trilobites from the Holy Cross Mountains, Poland: taxonomic, stratigraphic and biogeographic reappraisal. Acta Geologica Polonica, 63 (1), 57-87. Warszawa. Authorship issues are clarified, new photographic documentation is provided and emended systematic descriptions are presented for the oldest Cambrian trilobite taxa from the Holy Cross Mountains (Poland). Biostratigraphic analysis of the fauna allows correlation with the traditional Holmia kjerulfi-group Zone of Scandinavia, the Callavia Zone of Britain and Newfoundland, the lower and middle part of the Sectigena Zone of Morocco and the Marianian Stage of Spain. The trilobites display a strong biogeographic signal linked with West Gondwana and Avalonia and a suggestion is made that the TESZ margin of Baltica with the Małopolska Massif was liable to currents from those areas that distributed planktonic trilobite larvae.
Energy Balance of Hemp (Cannabis sativa L.) Grown for Energy Purposes
Authors: Kolarikova Michel , Havrland Bohumil , Ivanova Tatiana 
Published: April 2013

Abstract This article discusses the energy balance of the hemp biomass from the autumn and spring harvest which was used for the production of briquettes. The hemp plant (Cannabis sativa L.) used in this work is the variety Bialobrzeskie that was harvested on a trial plot in Prague-Suchdol in 2009 - 2010. Moisture content (MC), gross calorific value (GCV) and other technical parameters were evaluated for samples from the harvest of both periods. The autumn harvest results led to the assumption that the gross energy yield of the culture per superficies was 186.3 GJ ha-1. As compared to the previous results the spring harvest gave a gross energetic output of 161.4 GJ ha-1. The autumn harvest required more energy inputs compared to the spring harvest with values of 22.2 GJ ha-1 and 16.9 GJ ha-1 respectively. The most energy-consuming aspects of the biomass production were fuels (autumn) and the energy linked to the chemicals used (spring). Regardless of the higher net energy yield in autumn it was found that a spring harvest should be preferred because of its Energy Return on Energy Invested (EROEI) is 8.6. This is higher than for the autumn harvest (7.4).
Response of Poultry Agribusiness Risk to Financial Fragility and Macroeconomic Shocks in Nigeria (2004-2009)
Authors: Odemero Achoja Felix , Okereke Chukwuji Christopher 
Published: April 2013

Abstract Financial Fragility and Macroeconomic shocks make poultry agribusiness vulnerable to risk (unsteady profit). This tends to dampen investment drive and inhabits aggregate growth in the poultry sub-sector in Nigeria. To address this problem, time series data of 6 years (2004-2009) were collected from 200 randomly selected poultry farms. Multiple regression and t-test were used to analyse the collected data. T-test of return on investment shows that poultry agribusiness has low financial fragility and could be resilient enough to withstand macro-economic shocks. Co-integration results indicate that poultry agribusiness risks moves together with inflation rate, interest rates and real exchange rate. According to the results of vector autoregressive (VAR) test, it is shown that poultry agri-business risk is sensitive to macroeconomic shocks. But with sound financial structure, poultry agribusiness will be able to withstand financial fragility. The impacts-response analysis shows that increase in macroeconomic distortions leads to increase in poultry agribusiness risk in Nigeria. The results of study provided information on how macro economic shocks and fragile financial structure can trigger risk in poultry agribusiness sector. This information is very crucial to effective policy making and economic planning that will bring development to the poultry sector and the Nigerian economy. Factor analysis confirmed that inflation rate (0.0039) and interest rates (0.1218) are the significant distortion factors (P < 0.01) that exert more impact on poultry agribusiness risk. Regulated interest and inflation rates would stabilize earnings and lead to growth in poultry agribusiness in Nigeria.
Clinical Impact of Proximal Autosomal Imbalances
Authors: Hamid A.B. , Weise A. , Voigt M. , Bucksch M. , Kosyakova N. , Liehr T. , Klein E. 
Published: April 2013

ABSTRACT Centromere-near gain of copy number can be induced by intra- or inter-chromosomal rearrangements or by the presence of a small supernumerary marker chromosome (sSMC). Interestingly, partial trisomy to hexasomy of euchromatic material may be present in clinically healthy or affected individuals, depending on origin and size of chromosomal material involved. Here we report the known minimal sizes of all centromere-near, i.e., proximal auto-somal regions in humans, which are tolerated; over 100 Mb of coding DNA are comprised in these regions. Additionally, we have summarized the typical symptoms for nine proximal autosomal regions including genes obviously sensitive to copy numbers. Overall, studying the carriers of specific chromosomal imbalances using genomics-based medicine, combined with single cell analysis can provide the genotype-phenotype correlations and can also give hints where copy-numbersensitive genes are located in the human genome.
Chromosomal Polymorphisms Involved in Reproductive Failure in the Romanian Population
Authors: Mierla D. , Stoian V. 
Published: April 2013

ABSTRACT
Cytogenetic heteromorphisms are described as variations at specific chromosomal regions with no impact on phenotype. The purpose of this study was to investigate the effects of these chromosomal polymorphisms involved in reproductive failure in the Romanian population.
One thousand eight hundred and nine infertile patients, who were referred to Life Memorial Hospital, Bucharest, Romania, between January 2008 and April 2011, were investigated in this retrospective study. The frequency of chromosomal polymorphic variations was calculated for these patients. The control group is represented by 1116 fetuses investigated by amniocentesis between January 2009 and April 2011.
In this study 122 (6.74%) infertile patients and 63 fetuses (5.65%) showed chromosomal polymorphic variations. The differences between the two groups was not statistically significant (p <0.242) but there was statistical significance for some specific chromosomal polymor- phisms [inv(9),1qh+, 9qh+, fra(17)].
Some chromosomal polymorphic variations appear to be associated with reproductive failure. The statistically significantly higher incidence of heterochromatic variations found in infertile individuals emphasizes the need to assess their role in infertility and subfertility.
Ring Autosomes: Some Unexpected Findings
Authors: Caba L. , Rusu C. , Plăiaşu V. , Gug G. , Grămescu M. , Bujoran C. , Ochiană D. , Voloşciuc M. , Popescu R. , Braha E. , Pânzaru M. , Butnariu L. , Sireteanu A. , Covic M. , Gorduza E.V. 
Published: April 2013

ABSTRACT Ring chromosomes are rare entities, usually associated with phenotypic abnormalities in correlation with the loss of genetic material. There are various breakpoints and sometimes there is a dynamic mosaicism that is reflected in clinical features. Most of the ring chromosomes are de novo occurrences. Our study reflects the experience of three Romanian cytogenetic laboratories in the field of ring chromosomes. We present six cases with ring chromosomes involving chromosomes 5, 13, 18, and 21. All ring chromosomes were identified after birth in children with plurimalformative syndromes. The ring chromosome was present in mosaic form in three cases, and this feature reflects the ring’s instability. In case of ring chromosome 5, we report a possible association with oculo-auriculo-vertebral spectrum.
Mitochondrial DNA Mutations in two Bulgarian Children with Autistic Spectrum Disorders
Authors: Avdjieva-Tzavella D. , Mihailova S. , Lukanov C. , Naumova E. , Simeonov E. , Tincheva R. , Toncheva D. 
Published: April 2013

ABSTRACT Autism is a neurodevelopmental disorder of unknown origin that manifests in early childhood. Autism spectrum disorders (ASDs) refer to a broader group of neurobiological conditions, pervasive developmental disorders. Despite several arguments for a strong genetic contribution, the molecular basis in most cases remains unexplained. Several studies have reported an association between ASDs and mutations in the mitochondrial DNA (mtDNA) molecule. In order to confirm these causative relationship, we screened 21 individuals with idiopathic ASDs for a number of the most common mtDNA mutations. We identified two patients with candidate mutations: m.6852G>A that produces an amino acid change of glycine to serine in the MT-CO1 gene and m.8033A>G (Ile→Val) in the MT-CO2 gene. Overall, these findings support the notion that mitochondrial mutations are associated with ASDs. Additional studies are needed to further define the role of mitochondrial defects in the pathogenesis of autism.
Human Leukocyte Antigen-B27 and Disease Susceptibility in Vojvodina, Serbia
Authors: Vojvodić S. , Ademović-Sazdanić D. , Busarčević I. 
Published: April 2013

ABSTRACT There are numerous studies showing the role of human leukocyte antigens (HLAs) related with susceptibility or resistance to certain diseases. The aim of this study was to determine the association of HLA-B27 with ankylosing spondylitis (AS), polyarthralgia, lumboishialgia, acute anterior uveitis (AAU), psoriatic arthritis (PA), synovitis coxae and rheumatoid arthritis (RA) in patients from Vojvodina, Serbia. An HLA I class typing was performed by the serological immunomagnetic two-color fluorescence method using peripheral blood T lymphocytes in 97 patients and 224 healthy controls from the population of Vojvodina, Serbia.We calculated HLA-B27 frequencies, relative risk (RR), ethiologic fraction (EF), e.g., population attributive risk, when RR was greater than 1, while, preventive fraction (PF) was calculated when RR was lower than 1. This study revealed the strongest association of AS with HLAB27 antigen: RR = 25.0, while the EF was greater than 0.15, respectively. The χ2 test showed the significant difference (p <0.05) in HLA-B27 in patients with AS in comparison to controls (χ2 = 52.5). It was concluded that there is a positive association of HLA-B27 with AS and that HLA-B27 can serve as a marker for predisposition to diseases.
Learning to Generalize from Demonstrations
Authors: Browne Katie , Nicolescu Monica 
Published: April 2013

Abstract
Learning by demonstration is a natural approach that can be used to build a robot’s task repertoire. In this paper we propose an algorithm that enables a learner to generalize a task representation from a small number of demonstrations of the same task. The algorithm can generalize a wide range of situations that typically occur in daily tasks. The paper also describes the supporting representation that we use in order to encode the generalized representation. The approach is validated with experimental results on a broad range of generalizations.
New Applications of “Ontology-to-Text Relation” Strategy for Bulgarian Language
Authors: Staykova Kamenka , Osenova Petya , Simov Kiril 
Published: April 2013

Abstract
The paper presents new applications of the Ontology-to-Text Relation Strategy to Bulgarian Iconographic Domain. First the strategy itself is discussed within the triple ontology-terminological lexicon-annotation grammars, then - the related works. Also, the specifics of the semantic annotation and evaluation over iconographic data are presented. A family of domain ontologies over the iconographic domain are created and used. The evaluation against a gold standard shows that this strategy is good enough for more precise, but shallow results, and can be supported further by deep parsing techniques.