bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of microcarrier culture optimization on the glycosylation profile of a monoclonal antibody
Authors: Costa Ana Rita , Withers Joanne , Rodrigues Maria Elisa , McLoughlin Niaobh , Henriques Mariana , Oliveira Rosário , Rudd Pauline M , Azeredo Joana
Published: January 2013

Microcarriers are widely used for the large-scale culture of attachment-dependent cells with increased cell densities and, ultimately, higher product yield. In these processes, the specific culture conditions can affect the quality of the product, which is closely related to its glycosylation pattern. Furthermore, the lack of studies in the area reinforces the need to better understand the effects of microcarrier culture in product glycosylation. Consequently, in this work, the glycosylation profile of a monoclonal antibody (mAb) produced by adherent CHO-K1 cells grown in Cytodex 3 was evaluated under different conditions, and compared to that obtained of typical adherent cultures. It was found that microcarrier cultures result in a glycosylation profile with different characteristics from T-flask cultures, with a general increase in galactosylation and decrease in fucosylation levels, both with a potentially positive impact on mAb activity. Sialylation also varied but without a general tendency. This study then showed that the specific culture conditions used in microcarrier culture influence the mAb glycan profile, and each functional element (galactose, core fucose, sialic acid) is independently affected by these conditions. In particular, great reductions of fucosylation (from 79 to 55%) were obtained when using half volume at inoculation, and notable decreases in sialylation (from 23 to 2%) and glycoform heterogeneity (from 20 to 11 glycoforms) were observed for shake flask culture, potentially associated with the improved cell densities achieved in these culture vessels.
High prevalence of spondyloarthritis and ankylosing spondylitis among familial Mediterranean fever patients and their first-degree relatives: further evidence for the connection
Authors: Akar Servet , Soysal Ozgul , Balci Ali , Solmaz Dilek , Gerdan Vedat , Onen Fatos , Tunca Mehmet , Akkoc Nurullah
Published: January 2013

Introduction

Familial Mediterranean fever (FMF) is an auto-inflammatory disease characterized by recurrent attacks of fever and serositis. Limited data suggest that the prevalence of sacroiliitis is increased in patients with FMF. In our present study, we assessed the prevalence of spondyloarthritis (SpA), including ankylosing spondylitis (AS), among a cohort of FMF patients and their unaffected first-degree relatives (FDRs).

Methods

The current study cohort comprised a consecutive group of 201 unrelated patients with FMF and 319 FDRs (≥ 16 years old). These subjects were examined according to a standard protocol.

Results

A total of 157 FMF patients (78.1%) and 233 (73%) unaffected FDRs reported back pain. Fifteen FMF patients (7.5%) and nine unaffected FDRs fulfilled the modified New York (mNY) criteria for AS. One additional FDR with AS was identified after review of the medical records. None of the FMF patients with AS was HLA-B27 positive. The allele frequency of M694V among the FMF patients with radiographic sacroiliitis was significantly higher in comparison with those without sacroiliitis (OR 4.3). When compared with the general population, the risk ratios for SpA and AS among the FDRs of our FMF patients were 3.3 (95% CI; 2.0 to 5.5) and for AS 2.9 (95% CI; 1.3 to 6.4), respectively.

Conclusions

Our study suggests that a) factors other than HLA-B27 play a role in the association of FMF and SpA/AS; b) MEFV gene variations may be one of the geographic/region-specific potential pathogenetic links between these two disorders in the Turkish population.
The “Out of Africa” Hypothesis, Human Genetic Diversity, and Comparative Economic Development
Authors: Ashraf Quamrul , Galor Oded
Published: January 2013

This research advances and empirically establishes the hypothesis that, in the course of the prehistoric exodus of Homo sapiens out of Africa, variation in migratory distance to various settlements across the globe affected genetic diversity and has had a persistent hump-shaped effect on comparative economic development, reflecting the trade-off between the beneficial and the detrimental effects of diversity on productivity. While the low diversity of Native American populations and the high diversity of African populations have been detrimental for the development of these regions, the intermediate levels of diversity associated with European and Asian populations have been conducive for development. (JEL N10, N30, N50, O10, O50, Z10)
Innovation and Institutional Ownership
Authors: Aghion Philippe , Van Reenen John , Zingales Luigi
Published: January 2013

We find that greater institutional ownership is associated with more innovation. To explore the mechanism, we contrast the “lazy manager” hypothesis with a model where institutional owners increase innovation incentives through reducing career risks. The evidence favors career concerns. First, we find complementarity between institutional ownership and product market competition, whereas the lazy manager hypothesis predicts substitution. Second, CEOs are less likely to be fired in the face of profit downturns when institutional ownership is higher. Finally, using instrumental variables, policy changes, and disaggregating by type of institutional owner, we argue that the effect of institutions on innovation is causal. (JEL G23, G32, L25, M10, O31, O34)
Technological Diversification
Authors: Koren Miklós , Tenreyro Silvana
Published: January 2013

Economies at early stages of development are frequently shaken by large changes in growth rates, whereas advanced economies tend to experience relatively stable growth rates. To explain this pattern, we propose a model of technological diversification. Production makes use of input-varieties that are subject to imperfectly correlated shocks. Endogenous variety adoption by firms raises average productivity and provides diversification benefits against variety-specific shocks. Firm-level and aggregate volatility thus decline as a by-product of the development process. We quantitatively assess the model's predictions and find that it can generate patterns of volatility and development consistent with the data. (JEL D21, D24, E23, O33, O47)
Children's Resources in Collective Households: Identification, Estimation, and an Application to Child Poverty in Malawi
Authors: Dunbar Geoffrey R , Lewbel Arthur , Pendakur Krishna
Published: January 2013

The share of household resources devoted to children is hard to identify because consumption is measured at the household level and goods can be shared. Using semiparametric restrictions on individual preferences within a collective model, we identify how total household resources are divided up among household members by observing how each family member's expenditures on a single private good like clothing vary with income and family size. Using data from Malawi we show how resources devoted to wives and children vary by family size and structure, and we find that standard poverty indices understate the incidence of child poverty. (JEL I31, I32, J12, J13, O12, O15)
Efficient Coding of the Minimum Image Convention
Authors: Deiters Ulrich K.
Published: January 2013

The computation of distances between interactions sites while observing the minimum image convention is one of the most frequently performed operations in computer simulations of fluids. In this work several ways of encoding the minimum image convention are discussed and their performances on different computers compared. It turns out that the optimal choice for the algorithm depends on the computer type as well as the optimization level of the compiler, and that a well adapted algorithm can achieve a significant reduction of the computation time.
Second Osmotic Virial Coefficients and Aggregation of Monoclonal Antibodies by Static Laser Light Scattering
Authors: Dieterle Michael , Blaschke Tim , Hasse Hans
Published: January 2013

The second osmotic virial coefficient and the apparent molar mass of two human and one mouse monoclonal antibodies were measured in different aequeous buffer solutions which also contained sodium chloride or ammonium sulfate, respectively, by static laser light scattering in batch mode. The apparent molar mass indicates aggregation. At a constant pH value of 6.5 the sodium chloride concentration was varied from 0 to 2 M and the ammonium sulfate concentration from 0 to 0.8 M, respectively. A 20 mM sodium-phosphate buffer was used for all experiments. Furthermore the pH value was varied without adding additional salt from 4.5 to 10. The results of the salt dependency are in line with the Hofmeister-series. The results of the pH dependency correspond to the net charge of the molecules.
The Local Structure of Antimony in High Dose Antimony Implants in Silicon by XAFS and SIMS.
Authors: Sahiner M. Alper , Novak Steven W. , Woicik Joe C. , Takamura Yayoi , Griffin Peter B. , Plummer James D.
Published: January 2013

One of the important challenges in semiconductor industry is to sustain high concentration of dopant atoms electrically active in very small areas. In investigating the optimum post implantation treatment methods that will help to attain these conditions, the local structural information around the dopant atom is crucial. In this study, we have used secondary ion mass spectroscopy (SIMS) and x-ray absorption fine structure spectroscopy (XAFS) to obtain the concentration depth profiles and the local structural information around the Sb atom in laser thermal annealed (LTA) Sb implants in Si wafers. The Sb implant doses used in this work are 6.4x1015/cm2 and 2.0x1016/cm2. The XAFS results for the 6.4x1015/cm2 Sb dose sample do not exhibit any rhombohedral-Sb precipitation as the Fourier Transformed (FT) data can be fit successfully using only substitutional-Sb in the Si lattice sites. However, a multi-shell analysis of the Fourier Transformed (FT) data for the 2.0x1016/cm2 Sb dose sample clearly indicates there is a substantial contribution from the Sb-Sb scattering, which is a signature of precipitated form of Sb.
Instrumento de avaliação das Boas Práticas em Unidades de Alimentação e Nutrição Escolar: da concepção à validação
Authors: Stedefeldt Elke , Cunha Diogo Thimoteo da , Silva Júnior Êneo Alves , Silva Sueli Maria da , Oliveira Ana Beatriz Almeida de
Published: January 2013

O objetivo deste artigo é elaborar e validar instrumento de avaliação das Boas Práticas para Unidades de Alimentação e Nutrição Escolares. Estudo desenvolvido na cidade de Santos, realizado em dois momentos: 1) Elaboração da Lista de Verificação das Boas Práticas na Alimentação Escolar (Lista de Verificação BPAE) e; 2) Validação da Lista de Verificação BPAE com aplicação desta e de outras duas listas de referência em 76 escolas municipais. A sensibilidade e a especificidade foram estimadas por meio da Curva ROC - Receiver Operating Characteristics e a lista de verificação foi avaliada de acordo com a escala de Likert. Os blocos temáticos receberam pesos para o cálculo do percentual de adequação. Após aplicação das listas nas escolas foi observado valor de área sob a curva de 0,79 em relação à lista SS-196 e 0,85 para a Portaria 542/2006, indicando boa capacidade da Lista de Verificação BPAE em identificar inadequações. Esta lista recebeu avaliação positiva dos nutricionistas da alimentação escolar revelando que a mesma auxiliará na tomada de decisões para o controle de qualidade. A Lista de Verificação de BPAE elaborada e validada pode se constituir em importante instrumento para o controle de qualidade da alimentação escolar.
Perfil de mulheres com alta fecundidade em um grande centro urbano no Brasil
Authors: Soares Vânia Muniz Néquer , Schor Neia
Published: January 2013

Estudo quantitativo, descritivo que teve como objetivo conhecer e caracterizar as condições sociodemográficas, reprodutivas e de proteção social de mulheres que vivenciam alta fecundidade, em um grande centro urbano. A população pesquisada constituiu-se de 441 mulheres residentes em Curitiba que tiveram o quinto filho, ou mais, no ano de 2005, identificadas pela declaração de nascido vivo do último filho. Realizaram-se visitas domiciliares para entrevistas nos anos de 2006 a 2008. Para a coleta dos dados foi utilizado um questionário semiestruturado. Os resultados foram apresentados em tabelas com frequências absolutas e relativas, médias e desvio padrão, permitindo delinear o seguinte perfil: mulher migrante do interior do estado, residente há mais de dez anos na capital, vinda de família numerosa, com 35 anos em média e cinco anos de estudo, com mais de uma união, vivendo em união consensual, subempregada, com renda média aproximada de R$ 600,00, responsável por sete dependentes ou mais. Confirmando claramente a vulnerabilidade dessas mulheres e suas famílias. Conclui-se que a busca ativa de mulheres com alta fecundidade pelas equipes de saúde da família, priorizando suas necessidades, contribuiria para a redução das desigualdades sociais e em saúde a que elas estão sujeitas.
A tese da judicialização da saúde pelas elites: os medicamentos para mucopolissacaridose
Authors: Medeiros Marcelo , Diniz Debora , Schwartz Ida Vanessa Doederlein
Published: January 2013

O artigo avalia a hipótese de se a judicialização de medicamentos para o tratamento das mucopolissacaridoses no Brasil seria uma ação das elites econômicas. Debatem-se estudos prévios que defendem a tese da judicialização pelas elites em outros medicamentos. Discute-se, a metodologia desses estudos e as inferências dela derivadas e o respaldo empírico dessa tese no caso de um dos medicamentos judicializados de mais alto custo para o SUS. Foram analisados os 196 processos julgados entre fevereiro de 2006 e dezembro de 2010 que determinam a provisão gratuita dos medicamentos para mucopolissacaridoses pelo Ministério da Saúde. Há evidências de que os custos advocatícios sejam financiados por entidades interessadas nos resultados da judicialização, como as empresas distribuidoras ou indústrias farmacêuticas, de que pode haver migração dos pacientes para diagnóstico e tratamentos em centros universitários de referência para a inovação médica no país, e de que a opção por serviços públicos se dá por sua capacidade técnica e científica superior à de outras instituições. Logo, a advocacia privada, indicadores de exclusão social do local de residência dos pacientes e uso de serviços públicos não são informações de classe que corroborem ou refutem a tese da judicialização pelas elites.
Wilderness shapes contemporary fire size distributions across landscapes of the western United States
Authors: Haire Sandra L. , McGarigal Kevin , Miller Carol
Published: January 2013

In many U.S. federally designated wilderness areas, wildfires are likely to burn of their own accord due to favorable management policies and remote location. Previous research suggested that limitations on fire size can result from the evolution of natural fire regimes, specifically in places where fuels were recently reduced by previous burning. To explore the broader‐scale importance of fire management on wilderness landscapes, we selected three study regions representing diverse ecosystems in the western U.S. and modeled the change in fire size distributions across a gradient defined by wilderness/non‐wilderness boundaries. For randomly selected locations across the gradient, we derived a scaling parameter (α) using fire size‐frequency data for public lands (1984–2007); the parameter reflected the magnitude of change in the right tail of the fire size distribution where the largest fires reside. We then used quantile regression to model changes in α across the wilderness gradient, interpreting the results in terms of constraints on the relative role of large fires in structuring the fire size distribution. In the Southwest study region, the influence of large fires on size distributions decreased across the gradient toward wilderness at some places, suggesting that increased occurrence of natural burning, favored by wilderness management, led to limitations on fire sizes within recent timeframes. In contrast, we were unable to support the expectation that wilderness fire management limits the role of large fires in the Sierra Nevada and Northern Rockies study regions. Rather, the predominance of large fires increased toward wilderness interiors. Among spatial climate and topographic roughness variables included in our study, only winter and fire season precipitation limited fire size in the Northern Rockies, whereas several constraints on large fire occurrence operated in other regions. In southwestern ecosystems, evidence is needed to document stability in fire size distributions through time. In ecosystems of the Sierra Nevada and Northern Rockies, a longer temporal extent of observations may better match scales of disturbance and recovery. Our findings reflect the role of wilderness in addressing a fire deficit which has resulted from strong human influences on forests and fires over the past 150 years.
Cemented Versus Open Hole Completions: What is Best for Your Well?
Authors: Appleton Joel , Rivenbark Mark
Published: January 2013

For many years, the industry has relied on cemented and perforated liners to complete multistage stimulated oil and gas wells. However, the boom in tight oil and gas plays in North America and elsewhere have seen the emergence of open hole multistage system completions as a competitor to the traditional cemented liner.

Open hole multistage system completions found favor due to the efficiencies and cost savings realized by operator companies. These systems also made possible many more stages at an economic price point. But what about initial and ultimate recovery comparisons? Do open hole completions perform better or worse than cemented liners?

This paper will explain the differences between these competing completion options and present multiple case studies that have demonstrated operational, economic and production variances between cemented and open hole completions. This review will include a discussion of as important components to evaluating these competing completion techniques.
The Importance of Saturation History for Tight Gas Deliverability
Authors: Spain David R. , Merletti German , Webster Mike , Kaye Lindsay
Published: January 2013

Contemporary thinking on the origin of "basin centered" gas highlights the importance of proximity of mature source rocks to many low permeability gas reservoirs. The quality of gas charge determines the efficiency of the system; this is largely dependent upon source rock characteristics (oil versus gas prone) as well as the time sequence associated with hydrocarbon migration and reservoir unroofing. Examples exist where tight gas accumulations exhibit production of both condensed water and formation water. This can occur where low permeability reservoirs exist downdip or updip of pervasive gas saturation, where the source rock is not in proximity to the reservoir or where source rocks are lean or limited relative to the capacity of the reservoir rocks. Water production can also occur where the reservoir system has been breached, buried, or tilted and water has been imbibed to partially replace gas, thereby trapping a residual gas phase.

Dynamic rock typing "focuses on using petrophysical properties including rock type, porosity and effective permeability at reservoir conditions to divide the reservoir into flow units" (Liu et al, 2012); however, this should be done within the context of their saturation histories. Given the dynamic nature of some gas accumulations over a geologic timescale, it is important to model the relative permeability controls on gas and water deliverability using both drainage and imbibition models. A comparison of drainage versus imbibition models highlights the importance of saturation history, since minor variations in saturation can result in large changes in fractional flow and deliverability - depending upon whether drainage or imbibition conditions apply. Tight gas petrophysical studies must go beyond volumetrics and should consider both static (storage) and dynamic (flow) properties within the context of the petroleum system and the evolution of the current day pore geometry and fluid saturation distribution.
New Method for Inferring Fracture Aperture and Matrix Permeability Simultaneously Using Spontaneous Imbibition Data
Authors: Lu Juhong , Cheng Changhui , Li Kewen
Published: January 2013

It has been found experimentally that the relationship between the imbibition rate and the reciprocal of recovery by spontaneous water imbibition has two linear parts in rocks with fractures but has only one linear part in rocks without fractures. One of the two linear parts may represent the fracture property and the other may represent the matrix or the set of smaller fractures. A method to infer the effective fracture aperture (or permeability) and the matrix permeability simultaneously has been developed using the experimental data of spontaneous water imbibition in gas-saturated (dried) rocks. The mathematical model has been derived theoretically based on the fundamental laws of fluid flow in porous media. These include Darcy's law, material balance, and continuum equation. The theoretical model characterizes the relationship between imbibition rate and the reciprocal of recovery in both fractures and matrix. Several spontaneous water imbibition experiments have been conducted in rocks with different permeability, with and without fractures. Experiments have also been conducted in coal samples with fractures because of the importance in the production of coal bed methane. The values of the effective fracture aperture and matrix permeability of the core samples were inferred using the mathematical model derived in this study.
Applying Petrophysics and Systematic Completion Science to Increase Potential: A Terryville Field Tight Gas Case History
Authors: Modeland N.. , Buller D.. , Middaugh R.. , Wyszynski J.. , Sumrow H.. , Eckerman S.. , Graham J..
Published: January 2013

Few unconventional plays become successful by accident. Relying solely on what has historically been performed to dictate completion development without using resources available to gather the necessary petrophysical information about a play can often lead to disappointing production results. Misinterpreting well results can potentially lead to incorrect assumptions, which can require years to rectify. In the Terryville field of northern Louisiana, which is home to several productive tight gas sandstone layers, determining the correct development strategy was crucial to the economic sustainability for one emerging operator. By investing research, time, and money into the front end of the play’s development, a strategic plan was deployed that allowed an entire field (which might have only looked marginally economic in a favorable gas price environment initially) to be a profitable success story, even during a time of decreasing North American gas prices. By resurrecting old well logs for new rock model analysis, new insight was obtained from the field without any additional expense for drilling and logging operations. Some new vertical well logs were acquired as well, which helped fill in data gaps across the field. The information gleaned from these petrophysical rock models revealed potential in targets that might have otherwise been overlooked or regarded as uneconomical. Some of these targets proved worthy of lateral completions and have produced results that outperform many of the wells in the nearby Haynesville shale gas play. With a better understanding of the reservoir rock mechanics, decisions have been made more confidently about both well construction (where to land and in what direction) and well completions (how to stimulate for optimal results). By continually calibrating and improving the rock modeling of the field using post-completion science (i.e., tracer logs and pressure matching), the knowledge of the reservoir continues to be refined. This case history details the technology examples and resultant production that continue to make the Terryville field a success.
Challenges to Geosteering and Completion Optimization of Horizontal Wells in the Cotton Valley Formation, East Texas
Authors: Liu S.. , Lucas J. L. , Plemons P. A. , Zhou X.. , Zett A.. , Spain D. R. , Rabinovich M.. , Pour R. A. , Zhou Q..
Published: January 2013

Cotton Valley tight gas sands in the east Texas Basin of North America consist of very fine-grained, well-sorted quartz arenites and subarkoses that are overprinted by significant diagenetic processes. Stratigraphic variations in rock type control gas production. Hydraulic fracturing delivers economic gas production.

Recently, horizontal wells over 4,000 ft long consisting of more than twelve hydraulic fracturing stages have been drilled. The good gas producing rock type reservoirs are usually less than 14 ft thick and exhibit strong diagenetic overprint. Low gas prices challenge the use of sophisticated geosteering logs. Using a very basic Gamma Ray (GR) log and very limited offset pilot well data, chasing such thin and variable sand bodies over a distance of 4,000 ft in a marginal marine sedimentary environment is daunting. Apart from this, horizontal wells that target thin layers present unique challenges to completion optimization.

Quad-combo log data, including azimuthal density image data, was acquired using a Logging While Drilling (LWD) tool. Extensive log modelling was performed by combining the horizontal well logs with logs from its two offset vertical wells, and consistent interpretation was achieved. Log modelling has helped the post-drill well diagnosis in geosteering, completion design, and production performance. It has also supported formation evaluation.

This paper will highlight an integrated study workflow in tight gas sands using open-hole and cased-hole data. It will demonstrate the geosteering challenges, explain the log modelling process, and display the formation evaluation results. Geomechanical study, together with hydraulic fracturing data and production log data will be used to confirm that good gas producing rock types are easier to fracture, and they contribute better to production.
Eagle Ford Shale Well Control: Drilling and Tripping in Unconventional Oil and Gas Plays
Authors: Ridley K.. , Jurgens M.. , Billa R. J. , Mota J. F.
Published: January 2013

In late 2010, Shell began an Eagle Ford appraisal program at Piloncillo Ranch in South Texas. These wells are 8,500’ – 9,500’ TVD horizontals, with an average total depth of 14,500’ MD. Their primary target is the Cretaceous Eagle Ford shale. The Shell leases are located in the gas-condensate window. Shell is currently running a five rig development program. Initially, reservoir pressures were thought to be in the 12.5 ppg range, but Diagnostic Fracture Injection Tests (DFITs) showed the actual pore pressure to be greater than or equal to 14 ppg.

Initially, underbalanced drilling techniques were used to drill the 14-14.5 ppg formation with 11 ppg oil based mud. The Eagle Ford has no natural fractures in this area. As more wells were drilled, however, completion fracturing of offset wells began to cause well control problems, as induced fractures were encountered in horizontal sections during drilling. Initially, it was thought that additional casing strings would be required to deal with the higher pressures and flow capability of the 14-14.5 ppg fracture; however, through well control modeling and experience with underbalanced drilling in other tight gas environments, tripping and heavy pill spotting procedures were developed that allowed the wells to be drilled with the initial casing program.

This paper will describe the development of fit for purpose well control techniques used to drill underbalanced horizontal wells in the Eagle Ford shale gas play. It will discuss how the characteristics of tight shale formations in horizontal wells resulted in a different approach to well control and tripping procedures. Several simple techniques for establishing an understanding of real time data have helped to make decisions in the field with current information: Institute a dual density system to stop reservoir flow and prevent up-hole lossesCreate a Horner Plot for distinguishing ballooning from reservoir flow if losses are experiencedCreate a mud weight vs. influx flow plot for predicting flow changes with mud weightAscertain how the influx rate and location affect the time at which it would a take a well to unload to dry gas

The paper will also describe the software modeling used to determine influx responses and the methodology developed around it. This methodology is applicable to other tight shale formations drilled horizontally and developed around the globe. These procedures can significantly reduce non-productive time and minimize serious well control events on horizontal shale wells when properly followed.
Sensitivity Analysis on Parameters Affecting the Thickness of the Gas Hydrate Zone in the Gulf of Oman
Authors: Afazeli Erfan , Gerami Shahab , Badakhshan Amir
Published: January 2013

According to a recent seismic survey in the Gulf of Oman (GOO), hydrate bearing layers were detected through observation of significant bottom simulating reflector (BSR), flat spot and bright spot attributes. In addition, favorable geological conditions indicate possibility of gas hydrate formation in this region. Quantification of the hydrate resource using geological and geophysical techniques, while continuously improving is subject to very large uncertainties. Uncertainty associated with estimation of the thickness of the gas hydrate stability zone (GHSZ) is a source of error in prediction of the volume of hydrate-bound gas and gas production from gas hydrate reservoirs. In this paper we present a conceptual model of the thickness of the GHSZ varying over a wide range of input variables within the study area and use it along with sensitivity analysis to quantify the impact of these variables on the thickness of the GHSZ in the gas hydrate accumulations of the GOO. Using Milkov and Sassen's model, the thickness of the GHSZ is modeled on the basis of the GOO region properties for three kinds of gas hydrates with gas composition containing 100% methane, 95% methane and 90% methane. The results of sensitivity analysis show that geothermal gradient is the most effective parameter changing the thickness of the GHSZ, then seabed temperature and gas composition have the greatest impact, respectively. Furthermore, the results reveal that gas composition has indirect impact on the degree of influence of other parameters. Evaluating the source of the gas in the GOO, particularly at the beginning of the life of the reservoir which very limited information is available for engineering calculations is the usefulness of this sensitivity analysis.
Support Vector Machine Model: A New Methodology for Stuck Pipe Prediction
Authors: Chamkalani Ali , Pordel Shahri Mojtaba , Poordad Saeed
Published: January 2013

Stuck pipe is a common worldwide drilling problem, resulting significant increases in non-productive time and overall well cost. Many oil and gas reservoirs are mature and are becoming increasingly depleted of hydrocarbons which make stuck pipe more severe risks. This is due to the fact that decreasing pore pressure increases the chance of stuck pipe. Minimizing the risks of stuck pipe while drilling has been the goal of many operators recently. This paper describes a robust support vector regression (SVR) methodology that offers superior performance for stuck pipe prediction either mechanically or differentially using available drilling parameters. A new model is developed using drilling parameters such as measured depth, mud weight, plastic viscosity, yield point, gel strengths, PH and solid percent from different wells. The method incorporates hybrid least square support vector regression and Coupled Simulated Annealing (CSA) optimization technique (LSSVM-CSA) for efficient tuning of SVR hyper parameters. The algorithm is applied to classify the stuck types, i.e., differential stuck or mechanical stuck. Performance analysis shows that LSSVM classifier has high accuracy. Using intelligent system would help drilling industry to reduce Non-Productive Time (NPT) during operation in complex zones.
Real‐Time Soil Moisture and Salinity Profile Estimation Using Assimilation of Embedded Sensor Datastreams
Authors: Wu Che-Chuan , Margulis Steven A.
Published: January 2013

Treated urban wastewater has been increasingly used for irrigation to increase crop production, but inadequate management of this marginal quality saline water cannot only reduce crop yield but also degrade soil. To increase sustainability, a sound irrigation policy based on real‐time soil states is needed to avoid the adverse effects from excess salinity in soils. In real applications, uncertain model inputs and soil heterogeneity are expected when a modeling approach is used. In addition, sensor measurement information is generally insufficient to characterize the state of the soil profile in detail. To overcome these limitations, a monitoring and modeling system assimilating embedded sensor datastreams into a hydrologic model to improve real‐time soil state estimates over the whole profile of interest is examined with a wastewater reuse system in Palmdale, CA. Experimental results show that under an unknown heterogeneous soil, the filtering scheme is able to describe the spatial variability of moisture and soil solution electrical conductivity in soils due to direct state estimation by assimilating moisture and electrical conductivity measurements and also due to improved soil hydraulic parameter estimates through the data assimilation framework. Two data withholding validation experiments were conducted to evaluate the added value of assimilating measurements. The spatial data withholding experiment demonstrates that state predictions at unobserved areas can be improved via the assimilation if the soil system is relatively homogeneous and effects from erroneous irrigation forcing are reduced. The temporal data withholding experiment indicates that a high update frequency can maintain the reliability of state estimation. Overall, this system can provide a more accurate soil characterization that could be used to optimize irrigation management to reduce adverse effects from wastewater reuse.
Temperature Dependence of Thermal Properties of Sands across a Wide Range of Temperatures (30–70°C)
Authors: Smits Kathleen M. , Sakaki Toshihiro , Howington Stacy E. , Peters John F. , Illangasekare Tissa H.
Published: January 2013

Due to the dynamic nature of the shallow subsurface, knowledge of soil thermal properties across a wide range of soil moisture and temperature conditions is necessary to accurately describe heat transport in many settings. Soil thermal properties are difficult to measure at high temperatures, however, due to the lack of suitable measurement devices and the potential for measurement‐induced changes. Therefore, thermal property data are often scarce and incomplete and very often limited to specific soils. Due to this scarcity of accurate experimental data, empirical relationships often do not accurately predict the thermal properties of soils as a function of both soil moisture and temperature. In this study, thermal conductivity and diffusivity were measured for silica sands under loose and tight packing conditions and a field sand under varied water saturation and temperature. Several recent sensor‐based technologies were integrated into a small cell modified to have a network of sampling ports, continuously monitoring water saturation, temperature, and soil thermal properties. For the test sands studied, data showed that the thermal conductivity and diffusivity increased noticeably for sample temperatures >50°C. At sample temperatures between 30 and 50°C, any change in thermal properties with temperature was small. Thermal conductivities measured in this study were compared with independent estimates made using empirical models from the literature. In general, good agreement was observed for most thermal conductivity data when proper fitting parameters were established, except at intermediate saturation values.
Unfrozen Water Content in Representative Bentonites of Different Origin Subjected to Cyclic Freezing and Thawing
Authors: Kozlowski Tomasz , Nartowska Edyta
Published: January 2013

The unfrozen water content in frozen soils strongly influences heat and mass transport processes. Despite massive research work, the actual implications of the freeze–thaw process on unfrozen water still remain unknown. The main objective of this study was to examine the hypothetical effect of a number of previous freeze–thaw cycles on the unfrozen water content during the current cycle. Several bentonites (Stx‐1b from Wyoming, SWy‐2 from Texas, as well as Ca, Na, and K forms of bentonite from Chmielnik) with different water contents were subjected to repeated freezing to −90°C and thawing at 20°C in a differential scanning calorimeter (DSC). The total number of cycles was five. The unfrozen water contents were determined on warming during each cycle by the use of the stochastic deconvolution of the DSC signal. According to the ANOVA results, the freeze–thaw effect on the unfrozen water content wu in the bentonites was not statistically significant. A clear pattern of alterations of wu with the number of consecutive cycles could be distinguished, however, depending on the major exchangeable cation. The kind of exchangeable cation played a predominant role in the temperature dependence of the unfrozen water content. The specific surface area strongly affected the unfrozen water content at lower temperatures, i.e., at −5°C and below. Closer to 0?°C, the effect of the specific surface became absolutely insignificant, and the clay fraction content determined by the laser diffraction method proved to be the soil property best correlating with the unfrozen water content at −1°C.
Cycloidal algebras
Authors: Han Jeong , Kim Hee , Neggers J.
Published: January 2013

In this paper we introduce for an arbitrary algebra (groupoid, binary system) (X; *) a sequence of algebras (X; *)n = (X; ∘), where x ∘ y = [x * y]n = x * [x * y]n−1, [x * y]0 = y. For several classes of examples we study the cycloidal index (m, n) of (X; *), where (X; *)m = (X; *)n for m > n and m is minimal with this property. We show that (X; *) satisfies the left cancellation law, then if (X; *)m = (X; *)n, then also (X; *)m−n = (X; *)0, the right zero semigroup. Finite algebras are shown to have cycloidal indices (as expected). B-algebras are considered in greater detail. For commutative rings R with identity, x * y = ax + by + c, a, b, c ∈ ℝ defines a linear product and for such linear products the commutativity condition [x * y]n = [y * x]n is observed to be related to the golden section, the classical one obtained for ℝ, the real numbers, n = 2 and a = 1 as the coefficient b.
A note on meromorphically multivalent functions with missing coefficients
Authors: Liu Jin-Lin
Published: January 2013

The object of the present paper is to derive certain property of meromorphically multivalent functions with missing coefficients.
Comparison results for functional differential equations with impulses
Authors: Li Xiao
Published: January 2013

Comparison principles play an important role in the qualitative and quantitative study of differential equations. In this paper, we investigate a first order functional differential equations with impulses and establish new comparison results.
Groups of homeomorphisms on C(X) and pointwise limits
Authors: McCoy R.
Published: January 2013

This study looks at some subgroups of the group H(C(X)) of homeomorphisms on the space C(X) of continuous real-valued functions on a topological space X, where C(X) has the compact-open topology. The main result shows that, for certain spaces X, the subgroup of H(C(X)) generated by the algebraic and vertical homeomorphisms on C(X) is dense in H(C(X)) with the pointwise topology. Also, for X equal to the unit interval, a subgroup of H(C(X)) is developed using integration of the members of C(X), and this subgroup is used as an example and to illustrate certain properties that subgroups of H(C(X)) can have.
Suitability of Hybrid Acacia Wood for Manufacturing Plywood and Particleboard
Authors: Rahaman MM , Akhter K , Biswas D , Sheikh MW
Published: January 2013

Hybrid acacia, produced from natural crossing between two introduced timber species Acacia mangium and A. auriculiformies has been studied for assessing the suitability of plywood and particleboard manufacture. It was found that 1.5 mm thick smooth and figured veneer can be made and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flower and catalyzed (ammonium chloride) with 2% hardener under the specific pressures, viz., 1.05, 1.40 and 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the sample and their shear load at failure per unit area and percentage of wood failure were determined. 1.76 N/mm2 pressure for the manufacture of ply wood is found to be the best. The particleboard was tested for determining the strength and dimensional stability. The bending strength passed the standard specification, tensile strength was found to be low as per Indian standard. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12960 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 171-176, 2012
Approximate Solution of Fourth Order Near Critically Damped Nonlinear Systems with Special Conditions
Authors: Alom Md Asraful , Uddin M Alhaz
Published: January 2013

A perturbation technique has been developed based on the Krylov-Bogoliubov-Mitropolskii (KBM) method to investigate the solution of fourth order near critically damped nonlinear systems in the case of ?1??2, ?4 ? ?3 + 2?1 but ?4<2?3 among the eigenvalues ?1, ?2, ?3, ?4. The solutions obtained by this technique were compared with those obtained by numerical method. The method has been explained by an example. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12962 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 187-197, 2012
Composition, Temperature and Frequency Dependent Magnetic, Dielectric and Electrical Properties of Magnesium-Zinc Ferrites
Authors: Rahman M Mahbubur , Sheak Md Shahin , Pervin Soheli , Uddin Nasir , Ahmed Farid , Hossain Md Abul , Rahaman Mashudur , Bashar M Shahriar , Hossain Tofazzal , Akhter Shireen
Published: January 2013

Polycrystalline spinel MgxZn0.3Cu0.7-2xFe2+xO4, where x = 0.10, 0.20, 0.25, 0.30 and 0.35  ferrites (hereafter abbreviated as Mg-Zn) have been prepared by conventional double sintering technique. The samples were sintered at 1250°C in air for 6 hours. Measurements have been done at temperature and frequency ranges of 0 - 350°C and 0 - 500 kHz, respectively. In this work, some extrinsic magnetic properties such as Curie temperature, initial permeability, loss factor, quality factor, dielectric constant and resistivity of the samples have been studied. The Curie temperature and loss tangent of the samples decreased with increase in Cu-content whereas permeability, Qfactor, resistivity and dielectric constant have been noticed to be increased with the increase in Cucontent.  The decrease in Curie temperature related to fact of weakening the strength of exchange AB  interaction. Maxwell-Wagner type of interfacial polarization might have found correlated with  the normal dielectric behavior of the samples, however no relaxation peaks were observed in the  dielectric dispersion curves of the Mg-Zn samples in virgin state or doped state. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12963 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 199-212, 2012
Growth and Flowering Performance of Potted Gerbera, Gerbera Jamesonii L. Under Different Light Intensity
Authors: Uddin AFM Jamal , Das C , Shammy F H , Foysal M , Islam M S
Published: January 2013

The influence of different light intensities (L0: full sunlight; L1: reduced sunlight; L2: 60% reduced sunlight) showed significant variations on growth and flower characteristics. Forty per cent reduced sunlight was more effective on growth and flower production than 60% reduced or in full sunlight. Tallest and thickest peduncles were produced (28.5 and 1.7 cm, respectively) with L1, similarly bigger flowers (6.0 cm diameter) were also found with L1 in comparison to L0 and L2. The maximum number of flowers per plant (15.6) was found from L1 and lowest (11.9) from L2.DOI: http://dx.doi.org/10.3329/jbas.v36i2.12965Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 213-220, 2012
Substrate Temperature Effect on the Structural and Optical Properties of Znse Thin Films
Authors: Bhuiyan M R A , Miah M A H , Begum J
Published: January 2013

Zinc selenide (ZnSe) thin films were deposited on to chemically and ultrasonically cleaned  glass substrates at different substrate temperatures from room temperature to 200°C keeping the  thickness fixed at 300 nm by using thermal evaporation method in vacuum. The structural properties of the films were ascertained by X-ray diffraction (XRD) method utilizing a  diffractometer. The optical properties were measured in the photon wavelength ranging between 300 and 2500 nm by using a UV-VIS-NIR spectrophotometer. The XRD patterns reveal that the  films were polycrystalline in nature exhibiting f.c.c zincblende structure with average lattice parameter, a = 5.6873Å. The grain size, strain and dislocation densities of the films have bee calculated. The optical transmittance and reflectance were utilized to compute the absorption  coefficient, band gap energy and refractive index of the films. The band gap energy of the films  was extracted from the absorption spectra. The direct band gap energy of the films slightly increases with substrate temperature.DOI: http://dx.doi.org/10.3329/jbas.v36i2.12969Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 233-240, 2012
A Comparison of the Mineral Dust Absorptive Properties between Two Asian Dust Events
Authors: Logan Timothy , Xi Baike , Dong Xiquan
Published: January 2013

Asian dust events are generated by deep convection from strong low pressure systems that form over mineral dust source regions. This study compares the mineral dust optical properties of two strong Asian dust events from the winter (December 2007) and spring (March 2010) seasons using AERONET retrieved parameters from three sites along the dust event path: SACOL (dust source region), Xianghe (downwind mixed aerosol region), and Taihu (downwind pollution region). The parameters include: aerosol effective radius, optical depth (t), absorptive optical depth (tabs), their respective wavelength dependences or Angstrom exponents (a and aabs), and the spectral single scattering albedo (wo(λ)). The a440–870 values in both cases do not exceed 0.62 indicating coarse mode particle dominance at all three sites. The winter case is shown to have carbonaceous influences at all three sites as given by aabs440–870 between 1.3 and 1.8 with strong spectral tabs absorption. The spring case is more dust dominant with aabs440–870 of 1.7–2.5 (noting that the largest value occurred at Taihu) with strong tabs absorption primarily in the visible wavelengths. Comparison studies between the observed and theoretically calculated wo(λ) for the winter and spring cases have shown an excellent agreement except for the winter case at Taihu due to pollution influences. The comparison studies also suggest that wo(λ) is more sensitive to particle absorptive properties rather than particle size. The sharp increase in the aerosol radiative effect (ARE) during the dust events with AREBOA > ARETOA suggests a stronger aerosol cooling effect at the surface than at the TOA.